The true improvements will have to go outside the SAC ternary system. The core values explained in my last column come into play. The success of lead-free reliability is incumbent upon the supply side of solder materials. OEMs play an important role in propelling design-for-performance. Additionally, EMS operations can take up the initiative by selecting the right material for the targeted reliability through engineering ingenuity. Now, we have to resort to that old clich̩ Рinnovate and work out of the existing box for better performance
Wednesday, March 31, 2010
Lead-free Reliability - Enticing and Intriguing
Surface Mount Technology: "Within the SAC system, decreasing Ag content has recently drawn attention and been put in applications. A lower Ag dosage in a SAC system does bring advantages in specific properties if/when meeting that specific criterion is the priority. Keep in mind, however, that a lower Ag dosage expends some other positive properties. It should be noted that this approach does not change the overall characteristic behavior of SAC ternary system."
Future Challenges of Lead-Free Rework
Surface Mount Technology: "Historically, issues relating to SMT lead-free rework related primarily to managing the smaller process window of higher melting point lead-free alloys. Much research to date has focused on establishing lead-free rework profiles that successfully rework solder joints without exceeding the temperature limits of the component body being reworked, adjacent components, and/or bottomside mirrored components. Most of these past challenges related to assemblies — which were on the low to medium end of the spectrum in terms of thermal mass — have been addressed through process optimization and various shielding methods. The future challenges are primarily associated with new component technologies. Examples of such new components are package-on-package (PoP), quad-flat no lead (QFN), Fusion Quad (developed by Amkor), 01005s, and high I/O (1000 ) and fine-pitch devices (0.3 mm). Having to rework these new devices under highly dense conditions (e.g. consumer product types) or when assembled on thermally massive circuit boards (e.g. telecommunication assemblies) will form the bulk of future challenges.
Historial issues
Process window; temperature sensitive components; adjacent rework effects; mirrored component rework; site dress, pad damage.
Future challenges
High I/O reworks; large board reworks; PoP/MLF/QFN; 0.3-mm pitch; 01005; BGA socket/SMT connectors.
The 01005 component exemplifies the challenges associated with miniaturization. Smaller than a grain of salt, this form factor makes reworking 01005s very difficult (Figure 4). In addition to the difficulties in removing this component, the paste application and site dress process is equally challenging. Some have succeeding using automated methods of reworking 01005 components. An automated rework equipment vendor recently stated that, “Hand rework is virtually impractical due to the size of this component. High magnification optics and accurate machine placement capability are critical for reworking 01005 components.” From this vendor’s perspective, there are two very different rework scenarios to consider. The first involves removing the defective device with an automated rework machine (Figure 5) and reusing the residual solder to replace the device. The second involves removing the defective device, removing the residual solder, and reapplying new solder paste. Currently, the technology exists to remove the residual solder; however, the current equipment accuracy and methodology to apply solder paste on 01005 pads is still not fully developed.
New Alloys Lead to Test Innovations
Surface Mount Technology: "The problem with SAC alloys, particularly SAC105, is that they tend to contaminate contacts faster than SnPb. SAC105, with its reliability in drop tests, has become a favored alloy with mobile electronics manufacturers."
Fine-pitch BGAs are particularly difficult to contact, and fine-pitch spring probes have even higher resistances as a result of their smaller spring force. This, together with the tendency of SAC105 to contaminate spring probes, challenges test applications. When maintenance is required – as often as every 200 cycles for BGAs with SAC105 – cost of test goes up and production test cycles speeds go down. Contamination transfers from the package to the contact tip. The degree of contamination depends on the solder alloy used and is aggravated by high temperature, another hallmark of lead-free assembly.
Semiconductor materials buying declines 19%
Purchasing: "The global semiconductor materials market fell 19% to $34.6 billion, with most of the decline occurring in the first half of the year, according to trade association SEMI. While the decline in 2009 was significant, it was less than the 26% decline the semiconductor materials industry incurred in 2001.
Wafer fabrication materials totaled $17.9 billion, down from $24.2 billion in 2009, while packaging materials purchases amounted to $16.8 billion in 2009, compared to $18.3 billion last year, says SEMI.
All regional markets experienced double-digit declines except for China, which dropped about 9%. North America had the largest percentage decline as semiconductor materials revenue dropped 24% to $3.79 billion.
Semiconductor materials include a wide range of materials, including silicon wafers, photoresists, wet chemicals, gases, bonding wire and solder among others."
Wafer fabrication materials totaled $17.9 billion, down from $24.2 billion in 2009, while packaging materials purchases amounted to $16.8 billion in 2009, compared to $18.3 billion last year, says SEMI.
All regional markets experienced double-digit declines except for China, which dropped about 9%. North America had the largest percentage decline as semiconductor materials revenue dropped 24% to $3.79 billion.
Semiconductor materials include a wide range of materials, including silicon wafers, photoresists, wet chemicals, gases, bonding wire and solder among others."
Henkel Sees Market Improving, Increases R&D Effort
PCB007: "After a rough year for our industry, Henkel Global Marcom Director, Doug Dixon, offers his perspective of an improving global market.
He also assesses which markets are really heating up and which materials are seeing increased demand. Henkel also released Multicore DA100 solder paste during the show."
Fraunhofer develops laser soldered glass packaging for electronic components
Electro Optics: "The Fraunhofer Institute for Laser Technology ILT has developed an innovative packaging process for micro-components and electronic parts based on laser glass soldering, which is suitable for use in mass production and, because it uses lead-free solders, fulfils the stringent environmental regulations of the EU’s RoHS Directive. Electronic and electrical products have to meet a diverse range of increasingly exacting demands, including high integration density, the combination of various materials with specific functionality, and rising requirements for thermal and mechanical stability. Hermetic packaging with high long-term stability poses particular challenges for the production technology, which can no longer be met by conventional methods such as gluing and soldering."
The relatively new joining technique subjects the total component to only minimal thermal loading. Research scientists at the Fraunhofer ILT are currently developing the technique with the aim of introducing it soon into series production. In this joining method the solder consisting of a glass particle paste is first applied precisely to the cover of the component using a print mask. The solder is then pre-vitrified in a kiln at a temperature of 350–500°C depending on the type of glass paste used, so that the binders in the paste evaporate. After the solder has cooled the electronic component is joined to the cover. A defined and locally limited temperature increase is achieved by scanning the solder seam with a laser beam. The rest of the component is not affected by this application of heat. Owing to the high scanning speed of up to 10,000mm per second, the joining process is quasi-simultaneously controlled. The entire solder contour is evenly heated, the cover can sink into the liquid solder bath and is thus hermetically connected to the component. Compared with gluing, Fraunhofer claims that the laser-based method achieves a considerable increase in the durability of the entire micro-component, and the permeability of liquids and gases is practically zero. What’s more, the solder seam is completely free of bubbles and cracks.
The technique is expected to have applications in the medical sector, OLEDs, and other miniaturised, high-precision components.
Thursday, March 25, 2010
IMC during thermal ageing in SEM
Factiva: "'The formation of intermetallic compounds (IMC) and its effects at the interface between different metals has always been of interest for the electronics industry, contacts manufacturers and users. The purpose of this work is primarily to develop an in situ technique of thermally aging metallic samples within the vacuum chamber of a scanning electron microscope (SEM),' scientists in Varennes, Canada report.
'This setup enables ongoing observation of the formation and growth of intermetallic compounds within the chamber. Due to the amount of data available in literature, copper-tin specimens were chosen as a basis to validate the technique. Once the samples were thermally aged, energy dispersive X-ray (EDX) analyses as well as electron backscattered diffraction (EBSD) were done on the surfaces. Ex situ nano-indentation measurements were also performed on the IMC,' wrote H. Gauthier and colleagues.
The researchers concluded: 'Have shown that the IMC formation can be observed while aging within a SEM chamber.'
Gauthier and colleagues published their study in European Physical Journal - Applied Physics (Microscopic study of intermetallic compound formation by in situ method. European Physical Journal - Applied Physics, 2010;49(2):22905)."
'This setup enables ongoing observation of the formation and growth of intermetallic compounds within the chamber. Due to the amount of data available in literature, copper-tin specimens were chosen as a basis to validate the technique. Once the samples were thermally aged, energy dispersive X-ray (EDX) analyses as well as electron backscattered diffraction (EBSD) were done on the surfaces. Ex situ nano-indentation measurements were also performed on the IMC,' wrote H. Gauthier and colleagues.
The researchers concluded: 'Have shown that the IMC formation can be observed while aging within a SEM chamber.'
Gauthier and colleagues published their study in European Physical Journal - Applied Physics (Microscopic study of intermetallic compound formation by in situ method. European Physical Journal - Applied Physics, 2010;49(2):22905)."
IMPACT Conference 2010-Call for Paper
EMSNo: "Following the four-year experiences and achievements, the 5th International Microsystems, Packaging, Assembly and Circuits Technology Conference in conjunction with TPCA Show 2010 will take place in Taipei Nangang Exhibition Center during October 20 to 22, 2010. In the past two years, IMPACT got the excellent records with more than 190 papers presented in the conference and attendees from 17 nations. With the theme of 'Embrace IMPACT, Create Possibilities', IMPACT is striving to work out the advanced paper scope and reward policy to attract outstanding papers from the world. It aims to become the representative international technology conference of packaging, thermal, assembly and PCB field both in industry and academic areas. In the meantime, all IMPACT papers would be referred in IEEE Xplore with high exposure rate."
Taking the advantage of resources from industry, academic and research institute, IMPACT is organized by IEEE CPMT-Taipei, IMAPS-Taiwan, ITRI, National Tsing Hua University, SIPO and TPCA and co-organized by TTMA, I-Shou University, SMTA and Taiwan PCB Institute. The paper scope would be divided in to Microsystems, Packaging, Thermal Technology and PCB & Assembly Technology. In the former scope, it includes Advanced Packaging, Modeling & Simulation, interconnection & Nanotechnology and Thermal Management. Especially, 3D IC, TSV Connection and LED Packaging are the popular items in 2010. In the latter scope, Materials & Process, Inspection & Reliability, Electrochemical Processing and HDI are the main items. In addition, papers relative to Green Technology and Mechatronics & Automation are welcome to join IMPACT.
Heraeus develops resin-free flux
Factiva: "SUMMARY SOLDER PASTE WITH RESIN-FREE FLUX MATERIAL As per the invention a resin-free soldering paste is prepared from a metal powder, especially soft solder and a Gel, where the invention based Gel does not leave any residues during smelting of the metal powder on the metal surface. The invention based Gel is based on a storage stable compound of carboxylic acid, amine and solvent. Important uses are the application of soft soldering paste on power module, die-attach, chip-on-board, SiP (System in Package), during wafer bumping, especially on UBMs and SMT (Surface mounted technology) and especially painted circuits. Under the use of resin-free soft soldering paste, according to the invention, the cleaning of a protective painting after the soldering of an electrical joint becomes superfluous and reduces the build up of pores in soldering Bumps on the UBMs below 20 volume %.'
Name of Applicant: W.C. Heraeus GmbH
Name of Inventor: Schmitt Wolfgang, Loosz Christian, Breer Frank, Hornung Jurgen, Krebs Thomas and Trodler Joerg
Application No.: 2274/CHENP/2008 A
Date of filing of Application: 07/05/2008
Publication Date: 06/03/2009"
Name of Applicant: W.C. Heraeus GmbH
Name of Inventor: Schmitt Wolfgang, Loosz Christian, Breer Frank, Hornung Jurgen, Krebs Thomas and Trodler Joerg
Application No.: 2274/CHENP/2008 A
Date of filing of Application: 07/05/2008
Publication Date: 06/03/2009"
Wednesday, March 24, 2010
RoHS 2 on the Horizon - Surface Mount Technology
Surface Mount Technology: "In December 2008, the EU Commission revealed plans to modify the existing RoHS Directive, an initiative that has earned the nickname RoHS 2. The objective is to develop a regulatory process that is simple, understandable, effective, and enforceable. RoHS 2 is only a proposal at this time. The timing for approval and a deadline for implementation are unknown."
RoHS 2: What's Going to Change?
RoHS 2 will be a single all-inclusive document, replacing the original Directive and subsequent Decisions that added maximum concentration values (MCV) and exemptions. This should make the RoHS Directive easier to comprehend; however, the resulting document is wordy and complex. There is one key definition change; the term producer will be replaced by manufacturer, distributor, importer, and authorized representative. The Directive outlines compliance obligations for each of these. They will be responsible for various compliance activities; good documentation and record-keeping will be fundamental to complying with these new and expanded obligations.
Under RoHS, categories 8 (medical devices) and 9 (monitoring and control instruments) were exempt. Under RoHS 2, categories 8 and 9 must be RoHS-compliant starting January 2014. A new addition to category 9, industrial monitoring and control instruments, must be RoHS-compliant starting January 2017. However, the global supply chain will force medical devices and monitoring and control instruments to RoHS compliance well before the 2014 deadline – mostly due to limited availability of lead-containing components. RoHS 2 provides helpful examples of categories 1-10 (electrical and electronic equipment).
Under RoHS 2, four new substances of high concern are identified for assessment and possible inclusion in the Directive: hexabromocyclododecane (HBCDD – flame retardant); bis (2-ethylhexyl) phthalate (DEHP – PVC plasticizer and a dielectric in some capacitors); butyl benzyl phthalate (BBP – a PVC plasticizer); and dibutylphthalate (DBP – a plasticizer, used in some adhesives and inks).
Under RoHS 2, product marking will be required. The CE mark – a conformity marking for many products sold in Europe – will expand to include RoHS compliance. The CE mark will be the only approved marking that signifies RoHS compliance; any other markings that may confuse or mislead are prohibited. Member states will presume that all products bearing the CE mark are RoHS compliant.
The original RoHS legislation was based on the concept of self governance. Under RoHS 2, the manufacturer must create a written declaration of product conformity; it, along with relevant technical documentation, must be available for 10 years after the product reaches the market. A copy of the declaration of conformity and other relevant technical information must be available to relevant authorities upon request. RoHS 2 contains guidelines for information that should go in the declaration of conformity.
RoHS 2: What's Not Changing (Much)?
The original 6 restricted substances and their maximum concentration values will remain the same. Exemptions were a key part of the original RoHS Directive. Certain materials are exempt if no suitable alternative material is available for a specific application or if material availability is not sufficient to meet demand. RoHS 2 contains a list of exemptions similar to the original Directive and subsequent Decisions. Of the 29 existing exemptions, most will remain; some will contain amended wording; some will be withdrawn; a few will be added. Exemptions will now expire after a maximum of 4 years, so the new exemption list will include expiration dates. Manufacturers can re-apply (at least 18 months in advance) if suitable alternatives are not available. SMT
Conclusion
RoHS 2 is an evolutionary step in European environmental compliance. These new requirements mean a cohesive and documented corporate-level RoHS compliance assurance system (CAS) is an absolute necessity. RoHS 2 will likely go into effect in 2011 or 2012. Now is the time to develop and implement a strategy for complying with RoHS 2.
Nano copper, aluminium patent from Lockheed Martin
Factiva: "A composition may have metal nanoparticles having a diameter of 20 nanometers or less and have a fusion temperature of less than about 220 degree celsius. A method of fabricating the metal nanoparticles may include preparing a solvent, adding a precursor with a metal to the solvent, adding a first surfactant, mixing in a reducing agent, and adding in a second surfactant to stop nanoparticle formation.
Copper and/or aluminum nanoparticle compositions formed may be used for lead-free soldering of electronic components to circuit boards. A composition may include nanoparticles, which may have a copper nanocore, an amorphous aluminum shell and an organic surfactant coating. A composition may have copper or aluminum nanoparticles. About 30-50% of the copper or aluminum nanoparticles may have a diameter of 20 nanometers or less, and the remaining 70-50% of the copper or aluminum nanoparticles may have a diameter greater than 20 nanometers"
Creep and thermomechanical fatigue properties of in situ Cu6Sn5 reinforced lead-free composite solder
Scopus: "In this research, a composite solder, which consisted of the Sn-3.5Ag eutectic solder matrix and Cu6Sn5 intermetallic compounds (IMCs) as reinforcements, was prepared by in situ method. Cu and Sn metallic particles were added into the molten Sn-3.5Ag eutectic solder to form Cu6Sn5 reinforcements in solder matrix. After rolling, the Cu6Sn5 IMCs are crushed into fine particles and distributed uniformly in the composite solder. The creep and thermomechanical fatigue (TMF) properties of the Sn-3.5Ag eutectic solder and its in situ Cu6Sn5 reinforced composite solder joints were successively investigated.
The experimental results showed that the in situ Cu6Sn5 reinforced composite solder joint exhibited better steady-state creep strain rate, lesser TMF damages and higher residual shear strengths after different number of TMF cycles as compared to the Sn-3.5Ag eutectic solder joint. These indicated that the in situ Cu6Sn5 reinforced composite solder possessed excellent creep resistance and TMF properties. Besides, the fracture mode of the in situ Cu6Sn5 reinforced composite solder joint and the role of the in situ Cu6Sn5 reinforcing particles were analyzed."
Tai, F., Guo, F., Han, M.T., Xia, Z.D., Lei, Y.P., Shi, Y.W.
Beijing University of Technology, 100 Ping Le Yuan, Chaoyang District, 100124 Beijing, China
RPS introduces new military compliant lead tinning system
EMSNow : "The Anthem is the first of its kind to offer this level of high reliability military standards compliance in a small-footprint and affordable package. The Anthem is suited for high precision, low-mid volume in-house re-tinning of electronic components and leads. This product is available immediately and will be at APEX 2010/Las Vegas.
The Anthem System is based on 15 years of RPS experience in building low and high volume lead tinning systems. The Anthem is a next generation platform that delivers the same durability and precision for which RPS is known."
The Anthem System is based on 15 years of RPS experience in building low and high volume lead tinning systems. The Anthem is a next generation platform that delivers the same durability and precision for which RPS is known."
Tuesday, March 23, 2010
FCT Assembly Introduces NL930PT Pin Probable Solder Paste
Circuitnet: "FCT Assembly introduces its NL930PT no-clean, lead-free, halide-free pin probable solder paste. The product is unique in that it is a clear residue paste that can print down to low surface area ratios consistently. Combined with SN100C, this solder paste produces the most cosmetically appealing solder joint available on the market.
FCT Assembly wanted to develop a robust paste that could be used with both the SN100C and SAC305. NL930PT is that and much more. This paste is not only very cosmetically appealing when used with the SN100C, but it also has excellent pin probability, good print release down to .55 SAR when used with the Slic Stencil and excellent wetting on all surface finishes. All this is accomplished without using any halides."
FCT Assembly wanted to develop a robust paste that could be used with both the SN100C and SAC305. NL930PT is that and much more. This paste is not only very cosmetically appealing when used with the SN100C, but it also has excellent pin probability, good print release down to .55 SAR when used with the Slic Stencil and excellent wetting on all surface finishes. All this is accomplished without using any halides."
Monday, March 22, 2010
Cookson electronics and assembly post lower revenue
evertiq.com: "For solder products, sales of higher margin, more value-added products such as solder paste were less affected, with volumes unchanged between years, whereas volumes for the more commoditised products such as bar solder were down 30%. This trend reflected the continuing shift from wave soldering to surface mount technology for the production of PCB’s. The recycling, reclaim business has continued its recent volume growth, particularly in China where the new facility in Guangxi Province became operational at the end of 2008.
Underlying revenue was 33% lower in the first half of 2009 compared with the first half of 2008 but increased by 19% in the second half compared to the first half of 2009, reflecting both the improvement in trading conditions and also the normal seasonality of the business. Profit contribution for 2009 was some 41% lower than for 2008 (at constant exchange rates) with a small contribution in the first half but a more substantial contribution in the second half. The transfer of European solder paste production from Ashford, UK to Hungary was completed at the end of the third quarter of 2009."
Underlying revenue was 33% lower in the first half of 2009 compared with the first half of 2008 but increased by 19% in the second half compared to the first half of 2009, reflecting both the improvement in trading conditions and also the normal seasonality of the business. Profit contribution for 2009 was some 41% lower than for 2008 (at constant exchange rates) with a small contribution in the first half but a more substantial contribution in the second half. The transfer of European solder paste production from Ashford, UK to Hungary was completed at the end of the third quarter of 2009."
Ag, Zn in Cu eliminates Bi brittleness
Factiva: "To eliminate the Bi segregation and interfacial embrittlement of the SnBi/Cu joints, we deliberately added some Ag or Zn elements into the Cu substrate. Then, the reliability of the SnBi/Cu-X (X = Ag or Zn) solder joints was evaluated by investigating their interfacial reactions, tensile property, and fatigue life compared with those of the SnBi/Cu and SnAg/Cu joints,' scientists writing in the Journal of Materials Research report.
'The experimental results demonstrate that even after aging for a long time, the addition of the Ag or Zn elements into the Cu substrate can effectively eliminate the interfacial Bi embrittlement of the SnBi/Cu-X joints under tensile or fatigue loadings. Compared with the conventional SnAg/Cu joints, the SnBi/Cu-X joints exhibit higher adhesive strength and comparable fatigue resistance. Finally, the fatigue and fracture mechanisms of the SnBi/Cu-X solder joints were discussed qualitatively,' wrote Q.K. Zhang and colleagues, Chinese Academy of Science"
'The experimental results demonstrate that even after aging for a long time, the addition of the Ag or Zn elements into the Cu substrate can effectively eliminate the interfacial Bi embrittlement of the SnBi/Cu-X joints under tensile or fatigue loadings. Compared with the conventional SnAg/Cu joints, the SnBi/Cu-X joints exhibit higher adhesive strength and comparable fatigue resistance. Finally, the fatigue and fracture mechanisms of the SnBi/Cu-X solder joints were discussed qualitatively,' wrote Q.K. Zhang and colleagues, Chinese Academy of Science"
Shenyang Natl Lab Materials Sci, Shenyang 110016, People's Republic of China
SnTe
Factiva: "SnTe is the most common compound formed at the bismuth telluride/metal soldered junction of thermoelectric modules. It affects the mechanical and electrical properties of the soldered junction.'
'In the study we investigate the growth of SnTe compound during reaction between molten Sn-3.5Ag solder and tellurium at 250 degrees C. We found that the growth of SnTe is suppressed by Ag-Te bilayer compounds that block further reaction between liquid Sn and Te. With increasing reaction tithe, the SnTe morphology becomes rough as a result of coarsening of SnTe grains,' wrote C.N. Liao and colleagues, National Tsing Hua University.
The researchers concluded: 'The growth of SnTe grains follows the conservative ripening kinetics with the mean particle size proportional to one-third power of reaction time."
'In the study we investigate the growth of SnTe compound during reaction between molten Sn-3.5Ag solder and tellurium at 250 degrees C. We found that the growth of SnTe is suppressed by Ag-Te bilayer compounds that block further reaction between liquid Sn and Te. With increasing reaction tithe, the SnTe morphology becomes rough as a result of coarsening of SnTe grains,' wrote C.N. Liao and colleagues, National Tsing Hua University.
The researchers concluded: 'The growth of SnTe grains follows the conservative ripening kinetics with the mean particle size proportional to one-third power of reaction time."
Natl Tsing Hua University, Dept. of Materials Sci & Engn, Hsinchu 30013, Taiwan
Auburn University Lauds POSS Short-Stop As Impressive Way To Suppress Tin Whiskers In Lead Free Solders
Nanowerk: "The Space Research Institute’s Surface Science Laboratory at Auburn University has released their exciting test results of Hybrid Plastics’ Short-Stop, a novel sprayable, cost effective conformal coating for the suppression of tin whiskers in lead-free solder and electronic circuits.
Henry W. Brandhorst, Jr., Director of the Institute, lauded the material saying, “The results have been impressive and conclusive! Short-Stop absolutely prevented the growth of tin whiskers in electronic applications.
Henry W. Brandhorst, Jr., Director of the Institute, lauded the material saying, “The results have been impressive and conclusive! Short-Stop absolutely prevented the growth of tin whiskers in electronic applications.
It's also important that it does this at a highly affordable, very low cost because it is applied by spraying and only a very thin layer is required. Thus the overall cost and ease of application seems to be much lower than other types of conformal coatings. The other great thing about Short-Stop is that it can be applied either at the OEM stage of production or as an after-market application. My thanks to Hybrid Plastics for developing such an innovative, successful product that eliminates a problem that has vexed the electronics industry for a long time.”"
Direct metal printing of 3D electrical circuit using rapid prototyping
Scopus: "Rapid prototyping (RP) is a direct-writing technology that offers several advantages over subtractive manufacturing processing, including low material consumption and easy customizability. Recently, this technique has been studied not only manufacture production parts but also electronic manufacturing applications. In this research, the design and manufacture of printed circuits using RP printing of lead-based alloy having low melting temperature were performed."
SMTA Reliability Conference 2010 Papers
http://www.smta.org/files/Program_Layout.pdf
Effect of Soldering Method and Flux Type on Whisker Growth in SAC305
Keith Howell, Nihon Superior Co., Ltd.
Die Attach Solder and Solder Alternatives
Brian Toleno, Ph.D., Henkel Corporation
Roadmap of the Environmental Technologies in Electronics
Jacklin Adams, IBM Corporation
BGA Re-balling from Pb-free to SnPb
Stephan Meschter, BAE Systems
Foxconn sees on-month drop, but on-year increase in February 2010 revenues
EMSNo: "Foxconn Electronics (Hon Hai Precision Industry) has announced revenues of NT$121.47 billion (US$3.83 billion) for February 2010, down 10.91% on month, but up 46.83% on year, better than market watchers expected.
The company pointed out that the on-month drop in February revenues was mainly due to fewer working days caused by the Lunar New Year."
The company pointed out that the on-month drop in February revenues was mainly due to fewer working days caused by the Lunar New Year."
Melting and solidification properties of the nanoparticles of Sn3.0Ag0.5Cu lead-free solder alloy
Scopus: "In this paper, lead-free solder alloy nanoparticles of Sn3.0Ag0.5Cu were synthesized by chemical reduction with NaBH4 as reducing agent. The experimental results indicated that the major particle size of Sn3.0Ag0.5Cu nanoparticles was smaller than 100 nm. The melting and solidification properties of the Sn3.0Ag0.5Cu nanoparticles were studied by differential scanning calorimetry at different scanning rates.
It was evidenced by the differential scanning calorimetry curves that the melting temperature of Sn3.0Ag0.5Cu nanoparticles was lower than that of the bulk alloy. In addition, the undercooling of the Sn3.0Ag0.5Cu nanoparticles was in the range of 82.0-88.5 'C at different cooling rates, which was much larger than that of the Sn3.0Ag0.5Cu micro-sized particles, showing stronger cooling rate dependence."
Shanghai University, Shanghai, 200072, People's Republic of China
Further Observations on Tin Pest Formation in Solder Alloys
Scopus: "The most recent observations of the response of bulk samples of several commercial solder alloys, exposed to temperatures below the allotropic transition for tin (13'C) for extended periods, are reported. Damage associated with tin pest development has been arbitrarily graded into six levels, and the formation of visible α-phase warts used for comparative purposes.
Since the previous examination, some 2 years ago, tin pest has been observed for the first time in the traditional Sn-37Pb solder alloy after exposure at -18'C and -40'C, and actual warts were apparent in as-cast Sn-0.5Cu stored at -40'C and in as-cast Sn-3.5Ag after exposure at -18'C."
Bill Plumbridge, Open University
60th ECTC - Electronic Components and Technology Conference
60th ECTC | Electronic Components and Technology Conference: "The premier international packaging, components, and microelectronic systems technology conference, the Electronic Components and Technology Conference (ECTC) strives to offer our attendees an outstanding array of packaging technology information."
June 1 -4, 2010 | Paris Las Vegas |Las Vegas, NV USA
Solder material supplier Shenmao expects strong 2Q10
Digitimes: "Shenmao Technology, a solder bumping paste supplier, has said revenues for the second quarter are expected to hold level or grow from the first quarter. Revenues for the ongoing first quarter will exceed the prior quarter's levels, according to the company. The company also looks to a monthly revenue growth in March and April.
Orders for each product line have extended to the second quarter, and order visibility of PV ribbons has even extended to July. The company said it is running at full capacity on solder paste production and has an over 80% utilization rate for BGA solder spheres.
The company expects its revenues to follow the growth pattern of the notebook segment in 2010. Revenue share of PV ribbons will grow from current 1%, while BGA spheres' share of revenues will grow from 6% to 8% by the end of 2010. Notebook and EMS orders account for 50% of Shenmao's total revenues, and PCBs account for 20%."
Orders for each product line have extended to the second quarter, and order visibility of PV ribbons has even extended to July. The company said it is running at full capacity on solder paste production and has an over 80% utilization rate for BGA solder spheres.
The company expects its revenues to follow the growth pattern of the notebook segment in 2010. Revenue share of PV ribbons will grow from current 1%, while BGA spheres' share of revenues will grow from 6% to 8% by the end of 2010. Notebook and EMS orders account for 50% of Shenmao's total revenues, and PCBs account for 20%."
Flextronics southern China production site expects double-digit growth in 2010
Digitimes Systems: "Singapore-based EMS provider Flextronics International expects its production site in Zhuhai, southern China - the largest of the company's production bases around the world - to see a double-digit on-year revenue growth in 2010, according to Flextronics China vice president Fu Jun.
Flextronics' Zhuhai site saw an about 20% on-year drop in revenues in 2009 due to the economic recession, but as the global economy is recovering, the company expects strong orders in April, Fu said.
However, the increasing orders will also pose a challenge to the workforce, according to Fu. The Zhuhai base, with 90% of its employees coming from outside of the southern province of Guangdong, usually loses about 5% of its workforce after the Lunar New Year break. This year, the loss increased to 10% amid a serious labor shortage in China's coastal areas"
Flextronics' Zhuhai site saw an about 20% on-year drop in revenues in 2009 due to the economic recession, but as the global economy is recovering, the company expects strong orders in April, Fu said.
However, the increasing orders will also pose a challenge to the workforce, according to Fu. The Zhuhai base, with 90% of its employees coming from outside of the southern province of Guangdong, usually loses about 5% of its workforce after the Lunar New Year break. This year, the loss increased to 10% amid a serious labor shortage in China's coastal areas"
Magnetic solders from Yale University
Selected Science News:: "Now Ramirez and her team have developed a non-toxic solder made of tin-silver containing iron particles. Not only is using a tin-silver alloy an environmental advantage, the addition of iron particles has other benefits.
First, the iron makes the alloy much stronger than it would ordinarily be. When an external magnetic field is applied to the molten solder, these particles align themselves within the solder, making it even stronger once it again solidifies.
Second, the iron overcomes the problem of tin-silver having a higher melting point than traditional lead-based solders. By subjecting the solder to an alternating magnetic field, the solder can be selectively heated. This keeps surrounding materials at safe temperatures while melting only the solder itself.
Third, an external magnetic field can be used to remotely manipulate the solder, so it can be moved into hard-to-reach places, such as narrow vertical channels. This means that broken connections within devices can be “self-healed” by applying a magnetic field to melt the solder and attach the ends together.
“There is a whole range of possibilities for this new kind of solder,” Ramirez said. “In addition to helping make the fabrication of microelectronics more environmentally responsible, these new solders have the potential to solve technological challenges.”"
First, the iron makes the alloy much stronger than it would ordinarily be. When an external magnetic field is applied to the molten solder, these particles align themselves within the solder, making it even stronger once it again solidifies.
Second, the iron overcomes the problem of tin-silver having a higher melting point than traditional lead-based solders. By subjecting the solder to an alternating magnetic field, the solder can be selectively heated. This keeps surrounding materials at safe temperatures while melting only the solder itself.
Third, an external magnetic field can be used to remotely manipulate the solder, so it can be moved into hard-to-reach places, such as narrow vertical channels. This means that broken connections within devices can be “self-healed” by applying a magnetic field to melt the solder and attach the ends together.
“There is a whole range of possibilities for this new kind of solder,” Ramirez said. “In addition to helping make the fabrication of microelectronics more environmentally responsible, these new solders have the potential to solve technological challenges.”"
Toyota's Stalling Problem, Corolla, Matrix and Pontiac Vibe Affected
The College Driver: "If you thought Toyota's recall woes were over, think again. The federal government is now probing several complaints from customers who claim that their vehicles will randomly begin to stall.
The stalling concerns affect about 1.2 million Toyota Corolla, Toyota Matrix, and Pontiac Vibe models that were made between 2005 and 2007. Though the Pontiac Vibe was made by General Motors, the Pontiac Vibe is included in the investigation because it was made in the same plant as the Toyota Matrix, so the two vehicles share many parts.
The problem stems from a defect in soldered joints within the engine control module (ECM). After a period of time, the solder can loosen causing the ECM to short. When the ECM shorts the engine cuts off creating a stall or no start condition."
The stalling concerns affect about 1.2 million Toyota Corolla, Toyota Matrix, and Pontiac Vibe models that were made between 2005 and 2007. Though the Pontiac Vibe was made by General Motors, the Pontiac Vibe is included in the investigation because it was made in the same plant as the Toyota Matrix, so the two vehicles share many parts.
The problem stems from a defect in soldered joints within the engine control module (ECM). After a period of time, the solder can loosen causing the ECM to short. When the ECM shorts the engine cuts off creating a stall or no start condition."
IMAPS-UK "Beyond Solder" Technical Seminar announced
EMSNow: "IMAPS-UK, the UK Microelectronics Packaging Society has announced details of their one day technical seminar 'Beyond Solder' being held at the National Physics Laboratory, London on the 30 June 2010, in conjunction with the Innovative electronics Manufacturing Research Centre (IeMRC).
As engineers are presented with the challenge of fitting more functionality into smaller spaces, getting more power out of devices, dissipating increasing levels of heat from components and ensuring improved levels of reliability, the methods used for interconnect are often key in achieving these goals.
The IMAPS-UK 'Beyond Solder' Technical Seminar investigates the different interconnection methods being used and developed today, which overcome these challenges. These include ultrasonically bonded interconnects, reliable connections for harsh environments, conductive adhesives, press-fit connections for high reliability applications, parallel welding of ultra thin wires & ribbons, innovative die attach materials, flip chip connections & nano-scale interconnects."
As engineers are presented with the challenge of fitting more functionality into smaller spaces, getting more power out of devices, dissipating increasing levels of heat from components and ensuring improved levels of reliability, the methods used for interconnect are often key in achieving these goals.
The IMAPS-UK 'Beyond Solder' Technical Seminar investigates the different interconnection methods being used and developed today, which overcome these challenges. These include ultrasonically bonded interconnects, reliable connections for harsh environments, conductive adhesives, press-fit connections for high reliability applications, parallel welding of ultra thin wires & ribbons, innovative die attach materials, flip chip connections & nano-scale interconnects."
New reliability model from University of Limerick
Factiva: "This paper presents an alternative to the use of energy-based methodologies for life cycle predictions of solder interconnects. Isothermal mechanical cycling testing has been conducted using joint-scale solder samples on a novel testing apparatus.'
'The test data shows that work as a single parameter is insufficient in predicting failure; nor does the inclusion of cyclic frequency and mean temperature improve work-based methodologies. Here, a novel semi-empirical approach is presented in which stress, strain, strain rate and temperature are individually treated to create a model capable of predicting material behaviour under arbitrary cyclic loading conditions. The model constants are fitted to the results of the isothermal mechanical cycling tests, using load drop as a measure of damage. The calibrated model is then employed to predict the failure of a BGA device under thermal cycling,' wrote D. Herkommer and colleagues, University of Limerick.
The researchers concluded: 'The modelling results show state-of-the-art agreement with the test data and superiority over Morrow model constants from literature that have been applied to this data set.'
Herkommer and colleagues published the results of their research in Microelectronics Reliability (A reliability model for SAC solder covering isothermal mechanical cycling and thermal cycling conditions. Microelectronics Reliability, 2010;50(1):116-126)."
'The test data shows that work as a single parameter is insufficient in predicting failure; nor does the inclusion of cyclic frequency and mean temperature improve work-based methodologies. Here, a novel semi-empirical approach is presented in which stress, strain, strain rate and temperature are individually treated to create a model capable of predicting material behaviour under arbitrary cyclic loading conditions. The model constants are fitted to the results of the isothermal mechanical cycling tests, using load drop as a measure of damage. The calibrated model is then employed to predict the failure of a BGA device under thermal cycling,' wrote D. Herkommer and colleagues, University of Limerick.
The researchers concluded: 'The modelling results show state-of-the-art agreement with the test data and superiority over Morrow model constants from literature that have been applied to this data set.'
Herkommer and colleagues published the results of their research in Microelectronics Reliability (A reliability model for SAC solder covering isothermal mechanical cycling and thermal cycling conditions. Microelectronics Reliability, 2010;50(1):116-126)."
Arizona University - RE in SAC407
Factiva: "In this article, we report on the microstructure and mechanical properties of Ce- and Y-containing Sn-3.9Ag-0.7Cu solders. The microstructures of both as-processed solder and solder joints containing rare-earth (RE) elements (up to 0.5 wt pct) are more refined compared to conventional Sn-3.9Ag-0.7Cu, with decreases in secondary Sn dendrite size and spacing and a thinner Cu6Sn5 intermetallic layer at the Cu/solder interface,' scientists writing in the journal Metallurgical and Materials Transactions a - Physical Metallurgy and Materials Science report."
"These results agree well with similar observations seen in La-containing solders reported previously. The monotonic shear behavior of reflowed Sn-3.9Ag-0.7Cu-X(Ce, Y)/Cu lap shear joints was studied as well as the creep behavior at 368 K (95 A degrees C). The data were compared with results obtained for Sn-3.9Ag-0.7Cu and Sn-3.9Ag-0.7Cu-XLa alloys. All RE-containing alloys exhibited creep behavior similar to Sn-3.9Ag-0.7Cu. Alloys with Ce additions exhibited a small decrease in ultimate shear strength but higher elongations compared with Sn-Ag-Cu. Similar observations were seen in La-containing solders," wrote M.A. Dudek and colleagues, Arizona State University.
The researchers concluded: "The influence of the RE-containing intermetallics (CeSn3 and YSn3) that form in these alloys on the microstructural refinement, solidification behavior, and mechanical performance of these novel materials is discussed."
IPC APEX EXPO: Latest Research on Lead-Free Implementation Challenges & New Opportunities Drives IPC APEX EXPO™ Technical Conference
Facebook: "In the four years since the lead-free ban in electronics manufacturing went into effect, there has been a swarm of unintended consequences — new defects, reliability concerns, processing issues and challenges for high-reliability segments. With new research now available, lead-free implementation issues and solutions will be featured at the IPC APEX EXPO™ Technical Conference, April 6–8, 2010, in Las Vegas.
Sponsored by IPC — Association Connecting Electronics Industries, the conference includes 35 technical sessions featuring 99 technical papers by renowned experts in printed board manufacture, electronics assembly, environmental regulations, materials and test."
Sponsored by IPC — Association Connecting Electronics Industries, the conference includes 35 technical sessions featuring 99 technical papers by renowned experts in printed board manufacture, electronics assembly, environmental regulations, materials and test."
Friday, March 19, 2010
iNEMI Webinar Automotive 19/03/10
Automotive - lead-free sooner than expected. All new design requests now lead-free, conversion completing fast
Medical - pockets of research in implantables - long product lifecyles and shoratge of leaded components - but no requirement yet
Medical - pockets of research in implantables - long product lifecyles and shoratge of leaded components - but no requirement yet
Wednesday, March 17, 2010
Rare-Earth-Enabled Universal Solders for Microelectromechanical Systems and Optical Packaging
BNET: "Two lead-free solders, Au-20wt.%Sn eutectic solder (melting point = ~278C) and Sn-3.5wt.%Ag eutectic solder (melting point = ~221C) were doped with 2-2.5 wt.% of a RE element, such as lutetium (Lu), erbium (Er), or cerium (Ce). These RE-containing solders were synthesized by melting the component metals inside a quartz tube in a vacuum of ~10^sup -5^ torr. Remote magnetic-movement control was used to keep the RE metal at approximately room temperature while the base solder was being heated, and then, the RE was transferred rapidly into the molten solder alloy at the bottom of the quartz tube."
Shear pull testing of the solder bonds made with RE-containing solders indicated powerful bonding to various optical and electronic materials. The shear stress for fracture was typically in excess of ~1,000 psi (6.9 MPa). We have also used other RE elements, such as erbium (Er) and cerium (Ce), instead of lutetium (Lu) in some of our universal solders with essentially similar results.
Tuesday, March 16, 2010
ELV Solders Exemption extended to 2016
8(a). Lead in solders to attach electrical and electronic
components to electronic circuit
boards and lead in finishes on terminations
of components other than electrolyte
aluminium capacitors, on component pins
and on electronic circuit boards
Vehicles type approved before
1 January 2016 and spare parts
for these vehicles
X ( 1 )
L 48/14 EN Official Journal of the European Union 25.2.2010
8(b). Lead in solders in electrical applications
other than soldering on electronic circuit
boards or on glass
Vehicles type approved before
1 January 2011 and spare parts
for these vehicles
X ( 1 )
8(c). Lead in finishes on terminals of electrolyte
aluminium capacitors
Vehicles type approved before
1 January 2013 and spare parts
for these vehicles
X ( 1 )
8(d). Lead used in soldering on glass in mass
airflow sensors
Vehicles type approved before
1 January 2015 and spare parts
of such vehicles
X ( 1 )
8(e). Lead in high melting temperature type
solders (i.e. lead-based alloys containing
85 % by weight or more lead)
( 2 )
X
Monday, March 15, 2010
Consultation website for REACH 2012 review goes live
Chemical Watch : "Belgian environmental law consultancy Milieu has set up a website that will act as an official channel for stakeholders to give their views to a review of the REACH Regulation's relationship with other EU laws. Recently the European Commission contracted Milieu and three other companies, Pace, DHI and PTK, to complete a research project for the review by August 2011. The firms will compare REACH and the 167 other items of legislation they have..."
Monday, March 8, 2010
A Roundtable with EU RoHS Enforcement Authorities
123Signup
TechAmerica US and TechAmerica Europe, in collaboration with Symphony Consulting, Inc., will host a 60-minute webinar on "A Roundtable with EU RoHS Enforcement Authorities," on March 15, 2010 at 9:00 a.m. PST. In this webinar, three distinguished enforcement authorities from the UK (Mr. Chris Smith), the Netherlands (Mr. Roel Feijen), and Sweden (Ms. Christina Larsson) will discuss their approach towards RoHS enforcement. They will discuss what enforcement action has taken place, what violations are most common, how intelligence is gathered and shared among member states, and what documentation is required in a due diligence defense. In addition to viewing and listening to the presentation, you will have an opportunity to ask questions real-time through the Web Ex chat feature. Please join us for this informative webinar, which is designed to answer your questions about RoHS enforcement in EU member states.
Tuesday, March 2, 2010
Cookson reports H2 revival in sales and margins
ITRI: "Cookson Group, the world’s largest solder producer, reported much improved results in the July-December 2009 half year, as the acute de-stocking seen in the electronics and steel sectors in H1 abated. Apart from solders, the Group’s other main products are ceramics for the steel industry and precious metals. In a statement today Cookson also noted that “the improvement in steel production and electronics end-markets experienced in the second half of 2009 has continued so far into 2010.”"
Tin whisker test development-temperature and humidity effects part II: Acceleration model development
Scopus: "The incubation time for both whisker growth and corrosion in thin Sn platings (310 μm thick) on Cu-based alloys have been found to be well represented by an exponential function of humidity and an Arrhenius function of temperature for both as-deposited and reflowed tin platings. Furthermore, whisker growth was found to follow the same functionality in both corroded and non-corroded regions of the plating. The effective activation energies and humidity coefficients were found to depend upon plating thickness, exposure to reflow, and presence of corrosion."
Recovery of tin and copper by recycling of printed circuit boards from obsolete computers
Scopus: "This paper presents the experimental results for the leaching of printed circuit boards (PCB) from obsolete computers for extracting and recovering tin and copper by means of leaching followed by precipitation. Printed circuit boards were dismantled, cut into small pieces, and fed into a cylinder mill. The powder obtained was leached by using the aqueous solutions 2.18N H 2SO4, 2.18N H2SO4 3.0N HCl, 3.0N HCl, and 3.0N HCl 1.0N HNO3. The lowest values for the percentage of metal extraction were obtained with 2.18N H2SO4 (2.7% for Sn and lower than 0.01% for Cu), while the 3.0N HCl 1.0N HNO3 leach system exhibited an extraction of 98% for Sn and 93% for Cu. Precipitates were obtained at different pH values by neutralizing the leach liquors using NaOH. The 3.0N HCl 1.0N HNO3 leach system presented the highest recovery values from the powder feed (84.1% for Sn and 31.9% for Cu), as well as from the leach liquor (85.8% for Sn and 34.3% for Cu)."
A model for nucleation and growth processes of tin whisker
Scopus: "A model for the nucleation and growth processes of Sn whisker is offered. High density of localized screw dislocations by deformation form the dense spiral steps of atomic scale on Sn surface. The spiral steps would induce the nucleation of Sn whisker. Edge dislocations localized at the same region where the dense screw dislocations exist supply Sn atoms to Sn whisker through pipe diffusion. Both screw and edge dislocations would bend along almost one direction, namely, to relax the external shear stress. The image force also helps to bend the dislocations perpendicular to the whisker side-surface. The bending of dislocations at root of whisker leads the bend of whisker. The pipe diffusion of Sn atoms through edge dislocations from bulk Sn toward whisker is suppressed at the bent part of edge dislocation, resulting in release of Sn atoms inside whisker and leading to the growth of whisker near its root."
Effect of Ag addition on the corrosion properties of Sn-based solder alloys
Scopus: "Corrosion properties of three different Sn-Ag lead free solder alloys have been investigated in 0.3 wt% Na2SO4 solution as corrosive environment. As cast solder alloy was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Volume fractions of the Ag3Sn in the solders were determined by image analysis technique.
Pitting potential and corrosion potential for the alloys were determined by potentiodynamic tests. Electrochemical impedance spectroscopy (EIS) was carried out to measure the film and charge transfer resistance. Alloys with lower Ag content have been found as better corrosion resistance material"
SAC105 cf SAC396 Stress-Strain
Factiva: "New Pb-free alloys that are variations of the Sn-Ag-Cu (SAC) ternary system, having reduced Ag content, are being developed to address the poor shock load survivability of current SAC305, SAC396, and SAC405 compositions. However, the thermal mechanical fatigue properties must be determined for the new alloys in order to develop constitutive models for predicting solder joint fatigue.'"
"A long-term study was initiated to investigate the time-independent (stress-strain) and time-dependent (creep) deformation properties of the alloy 98.5Sn-1.0Ag-0.5Cu (wt.% SAC105). The compression stress-strain properties, which are reported herein, were obtained for the solder in as-cast and aged conditions. The test temperatures were -25A degrees C, 25A degrees C, 75A degrees C, 125A degrees C, and 160A degrees C and the strain rates were 4.2 x 10(-5) s(-1) and 8.3 x 10(-4) s(-1). The SAC105 performance was compared with that of the 95.5Sn-3.9Ag-0.6Cu (SAC396) solder. Like the SAC396 solder, the SAC105 microstructure exhibited only small microstructural changes after deformation. The stress-strain curves showed work-hardening behavior that diminished with increased temperature to a degree that indicated dynamic recrystallization activity. The aging treatment had a small effect on the stress-strain curves, increasing the degree of work hardening. The yield stresses of SAC105 were significantly less than those of SAC396. The aging treatment caused a small drop in yield stress, as is observed with the SAC396 material. The static modulus values of SAC105 were lower than those of SAC396 and exhibited both temperature and aging treatment dependencies that differed from those of the SAC396 material," wrote E.P. Lopez and colleagues.
E.P. Lopez, Sandia Natl Labs, POB 5800, Albuquerque, NM 87185, USA.
Tin Pest at Vienna University
Factiva: "Two samples of Sn-0.5Cu solder alloys, stored at -18A degrees C for 7 years, were chemically analyzed by an inductively coupled plasma-optical emission spectroscopy method,' investigators in Vienna, Austria report.
'One of the samples was unaffected by this exposure; the other one had completely transformed into brittle alpha-Sn. Ten elements were found to exhibit statistically significant differences in their concentrations between the two samples, with the higher always associated with the untransformed sample,' wrote M. Leodolterdworak and colleagues, University of Vienna.
The researchers concluded: 'The highest concentrations were found for elements with an appreciable solubility in Sn, i.e., Bi, In, Pb, and Sb"
'One of the samples was unaffected by this exposure; the other one had completely transformed into brittle alpha-Sn. Ten elements were found to exhibit statistically significant differences in their concentrations between the two samples, with the higher always associated with the untransformed sample,' wrote M. Leodolterdworak and colleagues, University of Vienna.
The researchers concluded: 'The highest concentrations were found for elements with an appreciable solubility in Sn, i.e., Bi, In, Pb, and Sb"
SnZnBi + SAC
Factiva: "The formation of intermetallic compounds and the shear strength of Sn-Zn-Bi solder alloys with various (0, 1, 3, 5 and 7 wt%) weight percentages of Sn-Ag-Cu were investigated on Au/Ni metallized Cu pads depending on the number of reflow cycles. In Sn-Zn-Bi solder joints, scallop-shaped AuZn3 intermetallic compound (IMC) particles were found at the interfaces and in the solder ball regions, fine Bi- and needle-shaped Zn-rich phase were observed in the Sn matrix,' investigators in Hong Kong, People's Republic of China report.
'After Sn-Ag-Cu additions, an additional Ag-Zn intermetallic compound layer was adhered to the top surface of the AuZn3 layer at the interface and fine spherical-shaped AgZn3 intermetallic compound particles were detected in the solder ball regions together with Bi- and Zn-rich phase volumes. After the addition of Sn-Ag-Cu, the shear strength of Sn-Zn-Bi solder joints increased due to the formation of the fine AgZn3 intermetallic compound particles,' wrote A.K. Gain and colleagues, City University of Hong Kong."
'After Sn-Ag-Cu additions, an additional Ag-Zn intermetallic compound layer was adhered to the top surface of the AuZn3 layer at the interface and fine spherical-shaped AgZn3 intermetallic compound particles were detected in the solder ball regions together with Bi- and Zn-rich phase volumes. After the addition of Sn-Ag-Cu, the shear strength of Sn-Zn-Bi solder joints increased due to the formation of the fine AgZn3 intermetallic compound particles,' wrote A.K. Gain and colleagues, City University of Hong Kong."
SAC+Ni In Zn at Chongqing University
Factiva: "In this paper, the microstructural evolution of IMCs in Sn-3.5Ag-X (X = 0, 0.75Ni, 1.0Zn, 1.5In)/Cu solder joints and their growth mechanisms during liquid aging were investigated by microstructural observations and phase analysis. The results show that two-phase (Ni3Sn4 and Cu6Sn) IMC layers formed in Sn-3.5Ag-0.75Ni/Cu solder joints during their initial liquid aging stage (in the first 8 min).'"
Thermal Analysis of the Sn-Ag-Cu-In Solder Alloy
Scopus: "The tin-based alloy Sn-1.5Ag-0.7Cu-9.5In (composition in wt.%) is a potential candidate for lead-free soldering at temperatures close to 200C due to the significant amount of indium. Samples of Sn-1.5Ag-0.7Cu-9.5In were prepared by controlled melting of the pure elements, followed by quenching to room temperature. The samples were analyzed by scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDS) and electron backscatter diffraction. The solidified melt consisted of four different phases. Solidification behavior was monitored by heat-flux differential scanning calorimetry (DSC). The phase equilibrium has been further investigated by thermodynamic calculations. The observed phase compositions as well as DSC signals are reasonably explained using the calculation of phase diagrams (CALPHAD) approach."
Sopoušek, J.a , Palcut, M.b d , Hodúlová, E.c , Janovec, J.b
a Institute of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, Brno, 611 37, Czech Republic
b Institute of Materials Science, Faculty of Materials Science and Technology, Slovak University of Technology, Trnava, 91724, Slovakia
c Institute of Production Technologies, Faculty of Materials Science and Technology, Slovak University of Technology, Trnava, 91724, Slovakia
d Division of Fuel Cells and Solid State Chemistry, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, Roskilde, 4000, Denmark
Effect of Rare-Earth (La, Ce, and Y) Additions on the Microstructure and Mechanical Behavior of Sn-3.9Ag-0.7Cu Solder Alloy
Scopus: "In this article, we report on the microstructure and mechanical properties of Ce- and Y-containing Sn-3.9Ag-0.7Cu solders. The microstructures of both as-processed solder and solder joints containing rare-earth (RE) elements (up to 0.5wtpct) are more refined compared to conventional Sn-3.9Ag-0.7Cu, with decreases in secondary Sn dendrite size and spacing and a thinner Cu6Sn5 intermetallic layer at the Cu/solder interface. These results agree well with similar observations seen in La-containing solders reported previously."
The monotonic shear behavior of reflowed Sn-3.9Ag-0.7Cu-X(Ce, Y)/Cu lap shear joints was studied as well as the creep behavior at 368 K (95 °C). The data were compared with results obtained for Sn-3.9Ag-0.7Cu and Sn-3.9Ag-0.7Cu-XLa alloys. All RE-containing alloys exhibited creep behavior similar to Sn-3.9Ag-0.7Cu. Alloys with Ce additions exhibited a small decrease in ultimate shear strength but higher elongations compared with Sn-Ag-Cu. Similar observations were seen in La-containing solders. The influence of the RE-containing intermetallics (CeSn3 and YSn3) that form in these alloys on the microstructural refinement, solidification behavior, and mechanical performance of these novel materials is discussed.
Dudek, M.A., Chawla, N.
School of Materials, Fulton School of Engineering, Arizona State University, Tempe, 85287-8706, United States
Microstructure and In Situ Observations of Undercooling for Nucleation of β-Sn Relevant to Lead-Free Solder Alloys
Scopus: "Difficult nucleation of β-Sn during solidification of tin and tin-based lead-free solder alloys can result in high degrees of undercooling of the liquid prior to solidification. The undercooling can produce solder joints with large grains, anisotropic behavior, and undesirable mechanical properties. This paper describes our examination of the amount of undercooling of tin on both graphite (non-wetting) and copper (wetting) surfaces using in situ x-ray diffraction. The microstructure was further characterized by optical microscopy,"
Effects of Zn addition on microstructure and tensile properties of Sn-1Ag-0.5Cu alloy
Scopus: "Effects of Zn addition on microstructure and tensile properties of Sn-1Ag-0.5Cu alloy were investigated. It was found that after the Zn addition, the Cu6Sn5 and Ag3Sn phases were gradually replaced by the Cu5Zn8, Ag5Zn8 and AgZn3 phases and the amount of them were increased with increasing Zn content.
The tensile tests showed that while the elongation of the alloy decreased with increasing Zn content, the strength was increased by Zn additions for Zn content <1 wt.%, but decreased at Zn content of 2 wt.%. The fracture surface analysis and deformed surface observation demonstrated that the fracture of the Sn-1Ag-0.5Cu-2Zn alloy was originated at the Ag5Zn8 phase. TEM observation further confirmed that the Ag5Zn8 phase was the weakness of the microstructure, accounting for the combination of the worst strength and elongation of the Sn-1Ag-0.5Cu-2Zn alloy."
Song, H.Y.a , Zhu, Q.S.a , Wang, Z.G.a , Shang, J.K.a b , Lu, M.c
a Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China
b Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
c IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, United States
Nihon Superior's Keith Sweatman to present at TMS 2010
EMSNow: "Nihon Superior Co. Ltd., a supplier of advanced soldering and brazing materials to the global market, announces that Keith Sweatman will present a paper titled 'The Relationship between Whisker Growth and Corrosion in Sn-3.0Ag-0.5Cu' at the upcoming TMS 2010 Annual Meeting & Exhibition, scheduled to take place February 14-18, 2010 at the Washington State Convention Center in Seattle. The presentation will be held during the session titled 'Pb-Free Solders and Emerging Interconnect and Packaging Technologies: Microstructure, Intermetallics, Whisker (II),' which is scheduled to take place Thursday, February 18, 2010 from 8:30-11:45 a.m."
Since the electronics industry moved to lead-free solders that typically have a tin content of more than 95 percent there has been concern about the possibility of circuit malfunctions due to whisker growth. It is now generally accepted that whisker growth is a response to compressive stress within the tin crystal and the challenge is to identify and eliminate or at least minimize the processes that can generate such stress.
Corrosion has been identified as one source of that stress and in this paper the authors report a study directed at identifying the relationship between the extent of corrosion and the concomitant whisker growth. Printed circuit coupons with an OSP finish were soldered with SAC305 solder using wave, reflow, and hand soldering methods with flux formulations typical of current commercial practice
Nihon Superior opens new office in Indonesia
EMSNowa: "Nihon Superior Co. Ltd., a supplier of advanced soldering materials to the global electronics industry, announces that its subsidiary Nihon Superior (Singapore) Pte. Ltd. is opening a representative office in Indonesia on February 8, 2010.
This new office will be staffed by Mr Wahyu Buditomo, who is relocating from the Singapore office. Mr Buditomo has eight years of experience with Nihon Superior in Japan and South East Asia and is looking forward to delivering even greater levels of support to customers in Indonesia.
CONTACT DETAILS
Mr Wahyu Buditomo
Indonesia Representative Office
Nihon Superior (Singapore) Pte., Ltd
43rd Floor, Wisma 46-Kota BNI
Jalan Jendral Sudirman Kav.
1 Jakata 10220
Indonesia
Tel: 62 81584163010
www.nihonsuperior.co.jp"
This new office will be staffed by Mr Wahyu Buditomo, who is relocating from the Singapore office. Mr Buditomo has eight years of experience with Nihon Superior in Japan and South East Asia and is looking forward to delivering even greater levels of support to customers in Indonesia.
CONTACT DETAILS
Mr Wahyu Buditomo
Indonesia Representative Office
Nihon Superior (Singapore) Pte., Ltd
43rd Floor, Wisma 46-Kota BNI
Jalan Jendral Sudirman Kav.
1 Jakata 10220
Indonesia
Tel: 62 81584163010
www.nihonsuperior.co.jp"
Coated solder metal particles
US7655304: "A method for preparing particles to retain a charge such that the particles are rendered electrostatically or electrokinetically mobile.
The method involves coating the particles with a coating medium which facilitates attachment of a charge director material, and contacting the particles with the coating medium thereon with a charge director medium to impart a positive or negative charge thereto and thereby render the particles electrostatically or electrokinetically mobile. Electrostatically and electrokinetically mobile particles for use in an electrostatic or electrokinetic deposition process. The particles include a coating medium and a charge director on particle bodies"
Solder Paste Dosing for Automotive and Other Applications
Adhesives & Sealants Industry: "Soldering pastes are often very abrasive and have a high content of solids (metal particles). The ViscoTec dispenser can handle these pastes and provide accurate and repeatable dosing based on the configurations programmed by the user.
Users will also benefit from the ViscoPro/RD dispenser system’s ability to integrate with a robot system, which makes the soldering process safer and more continuous. If there is a change or issue at the product-supply of the soldering paste, the buffering unit can feed the dispenser until soldering paste is added. The ViscoTreat-L features an evacuation tank and a funnel, which allows the product to be continuously stirred, thereby avoiding any settling of the paste. In addition, the setup allows for the degassing of the paste, ensuring better dosing results by way of fewer air bubbles. The ViscoTec stator/rotor technology allows the paste to be continuously pumped from the vacuum tank because the stator/rotor unit is vacuum tight."
Users will also benefit from the ViscoPro/RD dispenser system’s ability to integrate with a robot system, which makes the soldering process safer and more continuous. If there is a change or issue at the product-supply of the soldering paste, the buffering unit can feed the dispenser until soldering paste is added. The ViscoTreat-L features an evacuation tank and a funnel, which allows the product to be continuously stirred, thereby avoiding any settling of the paste. In addition, the setup allows for the degassing of the paste, ensuring better dosing results by way of fewer air bubbles. The ViscoTec stator/rotor technology allows the paste to be continuously pumped from the vacuum tank because the stator/rotor unit is vacuum tight."
IPC APEX EXPO 2010: Jetwave solder nozzle
Surface Mount Technology: "Pillarhouse will launch the Synchrodex Fluxer and Preheat combination module at IPC APEX. The fluxing operation can be performed by either the dropjet or ultrasonic application process. After the fluxing operation is complete, the IR preheater automatically heats the board to the set parameters. Preheating can be used from above and/or below and convection (using one, two or all three of these options)."
The bottom and topside IR preheating systems can also be monitored by closed loop systems for ease of set-up and use. Benefits of the system include smaller line footprints, faster throughput and added flexibility. With the successful release of the Jade Handex system in 2009, Pillarhouse will now release the patented sliding Bottom-side IR preheat for the Jade Handex. This new slide in/out bottom-side IR preheat system is controlled via the Pillarcomm software or the optional closed loop sensor systems. With the addition of the bottom-side unit, the Handex is now configurable with top and bottom IR heater to help process thermally challenging boards. Pillarhouse will introduce the patterned multi-directional rotating Jetwave solder nozzle system as well. Since the presentation of the moving solder bath systems, the pattern Jetwave solder nozzle technology has only been able to be used in single direction. This Jetwave solder nozzle rotation system now enables the machine to solder connectors that are positioned in any direction on a PCB without intervention. Pillarhouse USA Inc., www.pillarhouseusa.com,
Intel patent on hexagonal BGA array
Factiva: "Dave W. Young, Portland, Ore., has developed a method of arranging solder balls for ball grid array packages. The inventor was issued U.S. Patent No. 7,666,778 on Feb. 23.
The patent has been assigned to Intel Corp., Santa Clara, Calif.
According to the abstract released by the U.S. Patent & Trademark Office: 'A method of arranging solder balls in a hexagonal array on an integrated circuit package is disclosed. Arranging the solder balls in a hexagonal array may increase the solder ball density, reducing solder ball fatigue. In some embodiments, the solder balls are arranged in the hexagonal array under the die shadow and in an orthogonal array outbound of the die shadow"
The patent has been assigned to Intel Corp., Santa Clara, Calif.
According to the abstract released by the U.S. Patent & Trademark Office: 'A method of arranging solder balls in a hexagonal array on an integrated circuit package is disclosed. Arranging the solder balls in a hexagonal array may increase the solder ball density, reducing solder ball fatigue. In some embodiments, the solder balls are arranged in the hexagonal array under the die shadow and in an orthogonal array outbound of the die shadow"
Solder paste rheology from Greenwich University
Factiva: "Solder paste is the most important strategic bonding material used in the assembly of surface mount devices in electronic industries. It is known to exhibit a thixotropic behavior, which is recognized by the decrease in apparent viscosity of paste material with time when subjected to a constant shear rate.'
'The proper characterization of this time-dependent rheological behavior of solder pastes is crucial for establishing the relationships between the pastes' structure and flow behavior; and for correlating the physical parameters with paste printing performance. In this article, we present a novel method which has been developed for characterizing the time-dependent and non-Newtonian rheological behavior of solder pastes and flux mediums as a function of shear rates. We also present results of the study of the rheology of the solder pastes and flux mediums using the structural kinetic modeling approach, which postulates that the network structure of solder pastes breaks down irreversibly under shear, leading to time and shear-dependent changes in the flow properties. Our results show that for the solder pastes used in the study, the rate and extent of thixotropy was generally found to increase with increasing shear rate,' wrote S. Mallik and colleagues, University of Greenwich."
'The proper characterization of this time-dependent rheological behavior of solder pastes is crucial for establishing the relationships between the pastes' structure and flow behavior; and for correlating the physical parameters with paste printing performance. In this article, we present a novel method which has been developed for characterizing the time-dependent and non-Newtonian rheological behavior of solder pastes and flux mediums as a function of shear rates. We also present results of the study of the rheology of the solder pastes and flux mediums using the structural kinetic modeling approach, which postulates that the network structure of solder pastes breaks down irreversibly under shear, leading to time and shear-dependent changes in the flow properties. Our results show that for the solder pastes used in the study, the rate and extent of thixotropy was generally found to increase with increasing shear rate,' wrote S. Mallik and colleagues, University of Greenwich."
Monday, March 1, 2010
Indium Corporation Indium8.9HF
Indium Corporation White Papers: "In this work, a halogen-free lead-free no-clean solder paste system, Indium8.9HF series, has been developed. It exhibits superior oxidation tolerance, thus assures superior resistance against graping, head-in-pillow, solder balling, voiding, and poor wetting for miniaturized electronic applications. In spite of the immense challenge in material science, this system also shows outstanding probe testability, in addition to its very good printability, non- slump, SIR, and ECM performance. The superior performance of this Indium8.9HF system effectively sealed the gap caused by lead-free and halogen-free requirements."
Tin pest in lead-containing solders
Scopus: "The purpose of this paper is to describe the effects of mechanical testing and thermal treatment prior to storage at either - 18 or - 40C, for periods in excess of ten years on the Sn-37Pb alloy.
Design/methodology/approach - For over a decade, The Solder Research Group at The Open University has studied tin pest development in several of the new lead-free solders. Bulk samples, employed for mechanical testing, are laid down at - 18 and - 40C, and inspected periodically. Findings - In a previous examination in 2006, there was no evidence of tin pest formation in this alloy. On re-examination of the same specimens in 2008, about one in ten of the samples stored at - 18C, both 'as cast' and 'tested', exhibited warts of tin pest. Storage at - 40C increased this ratio to about one in three following treatment. Originality/value - The paper's findings demonstrate that, even with high concentrations of lead present, eventually tin pest will form. So, for interconnections used in long-term applications, whether lead-free or lead-bearing solders are employed, performance and structural integrity considerations should not ignore tin pest."
Heat-releasing printed circuit board and semiconductor chip package
US7663226: "A heat-releasing printed circuit board and semiconductor chip package are disclosed. The heat-releasing printed circuit board includes an insulation layer, on a surface of which a circuit pattern is formed, and a solder resist, which is stacked on the insulation layer, where the solder resist contains carbon nanotubes. The heat-releasing printed circuit board allows the heat generated in a semiconductor chip to be dispersed in several directions of the board or package, to improve heat-releasing property."
Samsung, Feb 2010
New Ceramic Sealed Hermetic Windows
PRWeb: "Windows produced with this new process are extremely robust and reliable because a key point of failure – solder joint fatigue – is eliminated. They provide a leak rate equal to or less than 1X10-9 cc/sec helium at 1 atmospheric differential pressure, even when subjected to extreme thermal and mechanical shock and, in medical applications, will maintain integrity after repeated autoclave sterilization.
Unlike solder- or braze-sealed windows, PA&E’s ceramic-sealed hermetic windows do not require metallization. Eliminating this step can, reduce both costs and processing time and allows anti-reflective coatings to be applied after the sealing process, ensuring that the critical A/R coating is not impacted by subsequent processing."
Unlike solder- or braze-sealed windows, PA&E’s ceramic-sealed hermetic windows do not require metallization. Eliminating this step can, reduce both costs and processing time and allows anti-reflective coatings to be applied after the sealing process, ensuring that the critical A/R coating is not impacted by subsequent processing."
Vapour phase or convection for lead-free?
Dataweek: "Vapour phase soldering (VPS) has been around in the industry for many years and was one of the only two serious options during the early introduction of surface mount technology. In the early days engineers had the option of brown belt for single sided products, infrared and VPS.
The first reflow system used by this author was VPS, preferring the simplicity of the process and process setup over the problems of accurate loading, board/belt positioning, profiling and overheating of paste causing flux residue charring."
The first reflow system used by this author was VPS, preferring the simplicity of the process and process setup over the problems of accurate loading, board/belt positioning, profiling and overheating of paste causing flux residue charring."
Sn1.5Ag1.7Sb + Al2O3 - Iran
Factiva: "Sn-1.7Sb-1.5Ag solder alloy and the same material reinforced with 5 vol.% of 0.3-mu m Al2O3 particles were synthesized using the powder metallurgy route of blending, compaction, sintering, and extrusion.
The impression creep behavior of both monolithic and composite solders was studied under a constant punching stress in the range of 20 MPa to 110 MPa, at temperatures in the range of 320 K to 430 K. The creep resistance of the composite solder was higher than that of the monolithic alloy at all applied stresses and temperatures, as indicated by their corresponding minimum creep rates,' scientists in Iran report."
SnZn+ RE Taiwan
Factiva: "'The effects of rare-earth elements on the microstructure and mechanical properties of Sn-9Zn alloys and solder joints in ball grid array packages with Ni/Au(ENIG) surface finishes have been investigated. Metallographic observations showed that (Ce0.8Zn0.2)Sn-3 and (La0.9Zn0.1)Sn-3 intermetallic compounds appeared in the solder matrix of Sn-9Zn-0.5Ce and Sn-9Zn-0.5La alloys, respectively.'"
H.J. Lin, Ind Technol Res Inst, Mech & Syst Res Labs, Hsinchu 310, Taiwan."
SAC Mechanical Properties
Factiva: "According to recent research from Tianjin, People's Republic of China, 'The creep behavior and hardness of Sn-3.5Ag-0.7Cu solder were studied using Berkovich depth-sensing indentation at temperatures of 25A degrees C to 125A degrees C. Assuming a power-law relationship between the creep strain rate and stress, an activation energy of 40 kJ/mol and stress exponents of 7.4, 5.5, and 3.7 at 25A degrees C, 75A degrees C, and 125A degrees C, respectively, were obtained.'"
Y.D. Han, Tianjin University, Sch Mat Sci & Engn, Tianjin 300072, People's Republic of China.
SnZn+ Research at Nanjing
Factiva: "According to a study from Nanjing, People's Republic of China, 'Wetting balance method is used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the solderability of Sn-9Zn lead-free solders, results show that the optimal addition amounts of Ga, Al, Ag, and Ce is 0.2, 0.002, 0.25, and 0.15 wt% respectively.
The surface property of Sn-9Zn-0.2Ga-0.002Al-0.25Ag-0.15Ce solder is studied by X-ray photoelectron spectroscopy and auger electron spectroscopy analysis; results indicate that Al aggregates on the surface as a compact aluminum oxide film which prevents the further oxidation.'"
"The aggregation of Ce on the subsurface can reduce the surface tension of solder, and improve the solderability accordingly. Meanwhile, SEM and XRD analysis indicate that Cu5Zn8 and AgZn3 intermetallic compounds form at the interface between Sn-9Zn-0.2Ga-0.002Al-0.25Ag-0.15Ce solder and Cu substrate, while AuZn3 and AuAgZn2 form at the interface between solder and Cu/Ni/Au substrate," wrote H. Wang and colleagues, NanJing University.
The researchers concluded: "Moreover, results also indicate that the mechanical property of soldered joints is improved duo to the dispersion strengthening effects of AgZn3 in Sn-9Zn-0.2Ga-0.002Al-0.25Ag-0.15Ce solder."
Wang and colleagues published the results of their research in the Journal of Materials Science - Materials in Electronics (Effects of Ga, Al, Ag, and Ce multi-additions on the properties of Sn-9Zn lead-free solder. Journal of Materials Science - Materials in Electronics, 2010;21(2):111-119).
For additional information, contact S.B. Xue, Nanjing University Aeronaut & Astronaut, Coll Mat Sci & Technol, 29 Yudao St, Nanjing 210016, People's Republic of China.
Status of the Proliferation of Lead-Free Alloys
EMSNow: "Status of the Proliferation of Lead-Free Alloys: 2010
Thursday, March 4, 2010
12-1:30pm Eastern / 9-10:30am Pacific
Ronald Lasky, Ph.D., PE, Indium Corporation
This webinar will provide an overview of the current lead-free alloy proliferation, a discussion of new failure modes and how to minimize them and an outlook on how alloy convergence might occur."
Thursday, March 4, 2010
12-1:30pm Eastern / 9-10:30am Pacific
Ronald Lasky, Ph.D., PE, Indium Corporation
This webinar will provide an overview of the current lead-free alloy proliferation, a discussion of new failure modes and how to minimize them and an outlook on how alloy convergence might occur."
Pd-doped Sn-Ag-Cu-In solder material for high drop/shock reliability
Scopus: "Pd was chosen as a minor alloying element in a new Sn-1.2Ag-0.7Cu-0.4In solder alloy to improve the drop/shock reliability. The tensile properties and drop/shock reliability of the new Sn-1.2Ag-0.7Cu-0.4In-0.03Pd solder alloy was compared with those of the Sn-1.0Ag-0.5Cu and Sn-3.0Ag-0.5Cu alloys.
The UTS, yield strength and elongation of Sn-1.2Ag-0.7Cu-0.4In-0.03Pd were superior to those of the other alloys tested. Sn-1.2Ag-0.7Cu-0.4In-0.03Pd showed outstanding drop/shock reliability compared to the representative Pb-free solder, Sn-3.0Ag-0.5Cu.
Therefore, the Sn-1.2Ag-0.7Cu-0.4In-0.03Pd composition is assessed to be an alternative Pb-free solder composition that may replace Sn-3.0Ag-0.5Cu."
Yu, A.-M.a , Kim, J.-K.b , Lee, J.-H.c , Kim, M.-S.a
a Division of Materials Science and Engineering, Inha University, 253, Yonghyun-Dong, Nam-Gu, Incheon, 402-751, South Korea
b Advanced Welding and Joining R, D Department, Microjoining Center, 7-47, Songdo-Dong, Yeonsu-Gu, Incheon, 406-840, South Korea
c Department of Materials Science and Engineering, Seoul National University of Technology, 172 Gongreung 2-dong, Nowon-gu, Seoul, 139-743, South Korea
Network of research and policy communities for innovation: An analysis of co-evolution of technology and institution
Scopus: "This study examines how collaboration networks are formed between universities, industry, and the public sector and work for the creation of environmental innovation through global co-evolution technology and institution."
The focus of this study is placed on the development of lead-free solders in the electric and electronic industry in Japan, Europe, and the United States. The structure of university-industry collaboration networks for lead-free solders is analyzed with the quantitative methods of social network analysis, based on data on the participants in research and development projects. Initiatives to regulate the use of lead in the United States influenced the formation of university-industry collaboration network for the development and adoption of lead-free solders in Japan. The network promoted cooperation and coordination among the relevant actors, including those working on chip implementation, solders, manufacturing equipment, parts, devices, printed circuit boards, and measurement instruments in implementing an effective transition to lead-free solders. The demonstration of technological progress in Japan in turn encouraged the introduction of a stringent regulation for the phase-out of lead-containing solders in Europe, leading to further formation of networks for technological development and adoption in other regions. Not involved in a domestic institutional network for regulating the use of lead, the university researchers in Japan, working from a relatively neutral position, took the initiative in creating international networks for the formulation of world-wide roadmaps for technological development and implementation, standardization of various specifications, and exchange and sharing of scientific and technological knowledge.
Yarime, M.
Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi Chiba 277-8563, Japan
Three-dimensional (3D) visualization of reflow porosity and modeling of deformation in Pb-free solder joints
Scopus: "The volume, size, and dispersion of porosity in solder joints are known to affect mechanical performance and reliability. Most of the techniques used to characterize the three-dimensional (3D) nature of these defects are destructive.
With the enhancements in high resolution computed tomography (CT), the detection limits of intrinsic microstructures have been significantly improved. Furthermore, the 3D microstructure of the material can be used in finite element models to understand their effect on microscopic deformation. In this paper we describe a technique utilizing high resolution (< 1 μm) X-ray tomography for the three-dimensional (3D) visualization of pores in Sn-3.9Ag-0.7Cu/Cu joints. The characteristics of reflow porosity, including volume fraction and distribution, were investigated for two reflow profiles. The size and distribution of porosity size were visualized in 3D for four different solder joints. In addition, the 3D virtual microstructure was incorporated into a finite element model to quantify the effect of voids on the lap shear behavior of a solder joint. The presence, size, and location of voids significantly increased the severity of strain localization at the solder/copper interface"
Dudek, M.A.a , Hunter, L.b , Kranz, S.a , Williams, J.J.a , Lau, S.H.b , Chawla, N.a
a School of Materials, Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-8706, United States
b Xradia Inc., Concord, CA, United States
Scopus - The adsorption of Ag3Sn nano-particles on Cu-Sn intermetallic compounds of Sn-3Ag-0.5Cu/Cu during soldering
Scopus: "The interfacial reactions between Sn-3Ag-0.5Cu solder and Cu substrate at 250 C and 300 C from 30 s up to 1800 s were investigated. The average size of the Ag3Sn nano-particles adsorbed on the Cu6Sn5 intermetallic compounds as a function of soldering temperature and time were studied.
The results show that the adsorption of Ag3Sn particles occurs during solidification process and the number of Ag3Sn particles increases with the morphology changing of Cu6Sn5 intermetallic compounds. When soldering at a fixed temperature, the average sizes of the Ag3Sn nano-particles are almost the same with the different soldering durations. However, the Ag3Sn nano-particles observed on intermetallic compounds are smaller at 300 C than those at 250 C. The Ag3Sn particles arrange in line in the same plane and the arrangements of Ag3Sn lines order two perpendicular orientations, but there are no relationship with the Cu6Sn5 surface orientations."
Liu, X.a , Huang, M.a , Zhao, Y.a , Wu, C.M.L.b , Wang, L.a
a Department of Materials Engineering, Dalian University of Technology, Dalian, Liaoning 116024, China
b Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, Hong Kong
The effects of solder volume and Cu concentration on the consumption rate of Cu pad during reflow soldering
Scopus: "The combined effect of solder volume and Cu concentration in solder on the Cu consumption rate is of significant practical importance but has never been satisfactorily addressed in literature so far. In this study, lead-free solder balls of different volumes (400, 500, 760 and 960 μm in diameter) and different Cu concentrations (Sn3AgxCu with x = 0, 0.3, 0.5, and 0.7 wt.%) were reflowed over Cu soldering pads in order to resolve this issue. The data obtained afforded the establishment of an empirical equation that could predict the Cu consumption during reflow. Such consumption rate information is crucial for designing the Cu conduction traces with minimum but reliable dimensions. Both the solder volume and the Cu concentration had marked effects on the morphology of the reaction product. Rationalizations for the effects on the consumption rate and the morphology are presented."
Chang, C.C., Lin, Y.W., Wang, Y.W., Kao, C.R.
Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei City, Taiwan
Solder jet printing benefits are coming to you!
Global SMT & Packaging magazine: "Solder jet printing now seen as a mainstream technology that will, in many applications, soon supplant traditional silk-screen solder paste application, so it is more important than ever for progressive electronics manufacturers to learn about its benefits.
By taking advantage of the MYDATA roadshow, they can do exactly that, without having to spend their valuable time travelling to a demonstration facility."
Electromigration-enhanced intermetallic growth and phase evolution in Cu/Sn-58Bi/Cu solder joints
Scopus: "This paper presents some experimental observations relative to the influence of elevated current densities on the intermetallic growth and phase evolution in Cu/Sn-58Bi/Cu solder joints.
Three samples were stressed with different current densities of 104, 1.2 � 104, and 1.4 � 104 A/cm2, respectively, for 80 h. The abnormal polarity effect of electromigration (EM) on chemical reactions at the cathode and the anode was investigated as well as the effect of EM on phase segregation in the two-phase eutectic microstructure."
He, H., Xu, G., Guo, F.
College of Materials Science and Engineering, Beijing University of Technology, 100 Ping Le Yuan, Chaoyang District, Beijing 100124, China
Nanoindentation of rare earth-Sn intermetallics in Pb-free solders
Scopus: "Incorporating rare earth (RE) elements into Sn-rich solder often results in the formation of RE-Sn intermetallics, which affect the deformation behavior of the solder. Little information is available on these constituent phases, and even less on their mechanical properties.
In this paper, we report on Young's modulus and hardness of LaSn3, CeSn3 and YSn3 intermetallic compounds formed in a Sn-Ag-Cu-2RE alloy, determined using nanoindentation. Nanoindentation on pure Sn was also performed for comparison. The Continuous Stiffness Method (CSM) was used during indentation to obtain the instantaneous Young's modulus as a function of depth. Scanning electron microscopy (SEM) was used to analyze the indentations after testing.
The measured values of Young's modulus for LaSn3, CeSn3 and YSn3 were 64 � 3, 69 � 3 and 98 � 4 GPa, respectively. Values of hardness for LaSn3, CeSn3 and YSn3 were 1.04 � 0.16, 1.03 � 0.03 and 3.47 � 0.27, respectively. Comparison of these values with limited data in the literature was conducted and is discussed."
Dudek, M.A., Chawla, N.
School of Materials, Ira A. Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-6106, USA
“Tin Whiskers” Implicated In Unintended Acceleration Problems
The Truth About Cars: "A number of articles have appeared implicating tin whiskers as a potential source or complicating factor in Toyota’s (and other manufacturers’) unintended acceleration issues.
The phenomenon of tin whiskers, a crystalline metallurgical phenomenon involving the spontaneous growth of tiny, filiform hairs from a metallic surface, can cause short circuits and arcing in electric equipment. First discovered in phone switching equipment in the 1940’s, the addition of lead to tin solder largely eliminated the problem. But the push to eliminate lead from electronic assemblies has led to a nasty re-growth of the pesky whiskers. And some are pointing fingers.
Satellites, including the failure of Galaxy IV, nuclear power facilities,pacemakers, and numerous other electronic assemblies have suffered from the effects of tin whiskering (here’s an explanation). In an article at TechEYE.net, a document that details the issues with lead-free soldering is referred to. Another expert in the field Henning Leidecker, chief engineer of the electronic parts office of NASA’s Goddard Space Flight Center in Greenbelt, Md., and an expert on tin whiskers, said in the last four years his office has been contacted by seven major suppliers of automotive electronics inquiring about failures in their products caused by tin whiskers.
Satellites, including the failure of Galaxy IV, nuclear power facilities,pacemakers, and numerous other electronic assemblies have suffered from the effects of tin whiskering (here’s an explanation). In an article at TechEYE.net, a document that details the issues with lead-free soldering is referred to. Another expert in the field Henning Leidecker, chief engineer of the electronic parts office of NASA’s Goddard Space Flight Center in Greenbelt, Md., and an expert on tin whiskers, said in the last four years his office has been contacted by seven major suppliers of automotive electronics inquiring about failures in their products caused by tin whiskers.
Response:
As an electronics equipment manufacturer, tin whiskers has caused serious problems for my business, including a major recall and repair program. I took almost a year to identify the root cause of the intermittent problem, hidden deep inside a power controller circuit board provided by a 3rd party that had recently switched to a lead-free process without notifying customers. They figured that the product was identical, except for the solder and lead finish of course. It took up to two years for the whiskers to grow and cause strange, intermittent problems to products that were mature, well-tested, high quality systems. It took another 6 months to recall and replace the faulty product.
So, if this is the problem, I can understand how Toyota couldn’t ID for a long time. On the other hand, my little company did.
NGOs seek nanosilver ban in RoHS recast
Chemical Watch: "NGOs seek nanosilver ban in RoHS recast
Groups lobby MEPs to draft new amendment
23-Feb-2010
Three environmental and health groups are urging members of the European Parliament's Environment Committee to draft a proposed amendment to the EU Directive on the restriction of hazardous substances (RoHS) in electrical and electronic equipment that would restrict the use of nanosilver to detectable limits in such equipment by 2014. The recent draft report on the recast from Parliament's rapporteur for the recast, Jill Evans, included proposed..."
Groups lobby MEPs to draft new amendment
23-Feb-2010
Three environmental and health groups are urging members of the European Parliament's Environment Committee to draft a proposed amendment to the EU Directive on the restriction of hazardous substances (RoHS) in electrical and electronic equipment that would restrict the use of nanosilver to detectable limits in such equipment by 2014. The recent draft report on the recast from Parliament's rapporteur for the recast, Jill Evans, included proposed..."
Subscribe to:
Posts (Atom)