ITRI Co-authored review of high temperature solders

SpringerLink: The substitution of lead in the electronics industry is one of the key issues in the current drive towards ecological manufacturing. Legislation has already banned the use of lead in solders for mainstream applications (T M≈220'C), but the use of lead in the solders for high-temperature applications (>85% lead, T M≈250-350'C) is still exempt in RoHS2.

The search for proper substitutes has been ongoing among solder manufacturers only for a decade without finding a viable low cost alternative and is the subject of intensive research.

This article tries to map the current situation in the field of high-temperature lead-free soldering, presenting a short review of current legislation, requirements for substitute alloys, and finally it describes some existing solutions both in the field of promising new materials and new technologies.

Currently, there is no drop-in replacement for lead-containing solders and therefore both the new materials and the new technologies may be viable solutions for production of reliable lead-free joints for high-temperature applications.

Companies request new RoHS exemptions

Companies have submitted nearly 20 requests for new exemptions under the RoHS directive on toxic substances in electrical and electronic equipment. Most requests involve the use of lead or cadmium in medical devices and monitoring instruments.

These two product categories were previously excluded from RoHS. A consultation run by consultancy Öko-Institut seeks stakeholder views on 18 exemptions requested by COCIR, which speaks for the medical equipment sector and the Test and Measurement Association. The European Sign Federation also made one request.

"The exemptions submitted by COCIR are for technologies which will have no viable alternative by 2014," explained secretary general Nicole Denjoy. "In some cases alternatives may exist, but the cost to healthcare would be unbearable, without any obvious benefit to patients and hospitals." The consultation will close in March.

SMTA Pan Pacific Microelectronics Symposium

SMTA: Response to last year's Roadmap Session encouraged SMTA to greatly expand the 2012 Roadmap program into a Global Summit on Electronics Industry Roadmaps. Three dedicated sessions include roadmap reviews from iNEMI, IPC, JISSO and IBM will also discuss why roadmaps are important to product competitiveness. Find out more at:

www.smta.org/panpac

Two Outstanding Keynote Addresses:

EU Electronics Research and Development Direction

by Christopher Bailey, Greenwich University

Pushing the Limits of Lead-Free Soldering

by Tetsuro Nishimura, Nihon Superior Co. Ltd.

Pan Pac Provides You The Latest Research On

Industry Roadmaps

Pb Free Advancements

3D Integrated Circuits

Evaluation and Failure Analysis

Strategic Manufacturing

Failure Modeling and Design

Process Advancement

and Green Technologies...

Two Outstanding Keynote Addresses:

EU Electronics Research and Development Direction

by Christopher Bailey, Greenwich University

Pushing the Limits of Lead-Free Soldering

by Tetsuro Nishimura, Nihon Superior Co. Ltd.

Pan Pac Provides You The Latest Research On

Industry Roadmaps

Pb Free Advancements

3D Integrated Circuits

Evaluation and Failure Analysis

Strategic Manufacturing

Failure Modeling and Design

Process Advancement

and Green Technologies...

Parliament approves new WEEE directive

The revised directive on waste electrical and electronic equipment (WEEE) has cleared one of its final legislative hurdles before becoming law, following a key vote in the European Parliament's plenary assembly in Strasbourg on Thursday.

The new rules, which introduce higher WEEE collection targets in the EU, are expected to enter into force in the summer following their publication in the EU's official journal. But they have to be formally rubber-stamped by the Council of Ministers first.

Member states will have 18 months after it enters into force to transpose the directive into national law. The details are contained in a compromise text agreed in mid-December by negotiators from the European Parliament and member states.

Some stakeholders expressed mixed feelings about the new rules following Thursday's vote in the parliament, noting that improvements had been made while also voicing disappointment. Others were more critical, saying EU legislators had failed to give producers of electronic and electrical goods enough regulatory certainty.

"What was meant to be a minor change to improve the functioning of this directive and offering industry more certainty as turned into a revision exercise with areas such as the scope still as unclear as before", said Adrian Harris, head of industry group Orgalime.

Stéphane Arditi of green group EEB agrees certain areas of the text are unclear, particularly the definition of large-scale fixed installations, one of several product categories that are excluded from the WEEE directive's scope.

In a statement on Thursday, EEB was also "outraged" by an apparent loophole in annex VI of the law which allows defective electronic or electrical equipment for professional use to be sent to developing countries for testing. These countries are ill-equipped to deal with hazardous substances contained in these products, it says.

SME association UEAPME was concerned about a take-back obligation for small equipment such as electric toothbrushes. Retailers with more than 400 square metres of sales area will have to comply. UEAPME says this includes larger SMEs.

NGO umbrella body RREUSE deplored the failure of legislators to set separate 'prepare for reuse' targets in the revised directive. The European Commission has been asked to investigate the feasibility of introducing such targets at a later stage.

Follow Up:
European parliament press release plus reactions from small firms' association UEAPME, industry group Orgalime, trade association RREUSE and EEB

Electronic waste: EU adopts new WEEE law

BBC News: The European Parliament has passed a new law to curb dumping of electronic goods such as mobile phones, computers and TV sets in landfill sites.

From 2016 EU member states will have to collect 45 tonnes of e-waste for every 100 tonnes of electronic goods put on sale during the previous three years.

By 2019 the target must rise to 65 tonnes, or member states can opt to collect 85% of total e-waste generated.

Retinning components - Article by ACE Production

Electronics Industry Update magazine p20-21 

Conflict Minerals & the SEC

LinkedIn: Conflict Minerals & the SEC ebnonline.com
What does the delay in issuing rules governing the implementation of conflict mineral laws mean for the electronics industry?

Tony Hilvers, IPC

DfR Presentation on latest Lead-Free developments

Website Link

Interesting summary ...

• Tin whiskers are a risk but can be significantly mitigated with awareness and precautions.
• High strain rate failure of SAC305 solder joints require careful material handling, design, and in some cases reinforcement of components.
• Select and optimize material sets (laminates, solders, surface finishes).
• Be aware of the various manufacturing defects and inspect for them.
• Head-in-pillow defects must be addressed in the material specification and assembly process.
• Rework profiles must be well documented and controlled (process window is much smaller than with SnPb)

Int. Conf. Soldering and Reliability (Toronto, ON: May 15-19)

Event website

Following on the very successful 2005 and 2006 International Conferences on Lead-free Soldering, and the SMTA International Conference on Soldering and Reliability held in Toronto, Ontario, Canada since 2007, this conference brings together a community of soldering and reliability experts.
Submit an abstract for 2012!

The Technical Committee would like to invite you to submit an abstract for this program. Deadline for submittal is January 27, 2012. Show off your company's expertise by presenting a paper. Abstracts can be submitted quickly and easily from the Call for Papers page.

Suggested topics to be covered include:
Lead-free Assembly and Test
Reliability
Harsh Environment
Tin Whiskers
New Alloys
Electromigration
Thermal Dissipation
Environmental Compliance/Regulations
Conformal Coating
   
Manufacturing Process
Package on Package
Corrosion
Halogen-Free Laminates
High Density Interconnects
Thermal Interface Materials
Underfill
Printed Electronics
Die Attach Soldering & L-F Challenges

Electronics Goes Green 2012+

Abstracts should cover at least one of the following topics:

Legislative Developments
Life Cycle Engineering
Critical Resources and Sustainability
Green IT
New Technologies
Corporate Social Responsibility and Management

Event website

Emerging Product-Targeted Environmental Regulations and Updates - A DCA Webinar

DCA Webinar: This 90-minute webinar will provide overviews of some of the most important and potentially challenging regulations that material and component suppliers, product manufacturers, distributors and exporters will face this year. The webinar includes expert insights from DCA's three principals on regulations and issues that have the potential to impact your company's ability to produce products or access markets.

Following the webinar, registered attendees will receive

A recording of the webinar, and
A PDF file of the presentation material

Webinar Agenda

Introduction, Environmental Regulatory Update and Overview
India RoHS/WEEE
California Safer Products Regulation Status
Conflict Minerals & Risk Mitigation in the Supply Chain
Vietnam RoHS
Existing Regulations - Short Update on EU REACH and EU WEEE Recast
Q&A

Cost: $149

Printed Electronics Start to Show Up in Volume Hybrid Products

SEMI.ORG: But 2012 will see introduction of an assortment of potentially significant new applications of wide-area, solution-processed materials in commercial lighting and displays, including potentially lower cost OLED light panels, better ITO alternatives, force-sensitive touch screens, and possibly even some flexible display backplanes.

Packaging Community Takes on New Challenges through Industry Collaboration

SEMI.ORG: The collaborative work of the packaging programs committees has also produced outstanding sessions focused on the intersection of semiconductor packaging technology and business.

In the second half of 2011 alone, the Americas Advanced Packaging Committee developed sessions which brought together industry leaders in 3D and 2.5D as well as heterogeneous integration of devices, while at the same time keep a focus on developments on packaging technologies that are needed in the near term.

The SEMI Taiwan Packaging & Testing Committee developed the inaugural SiP Global Summit, which was a three-day intense look at 3D-IC packaging and test technologies as well as embedded substrates.

The Advanced Packaging Committee of Europe delivered two half-day sessions at SEMICON Europe which took a hard look specifically at manufacturability with respect to technologies, materials, processes and equipment.

And the Japan Packaging Committee developed two sessions of strong technical content covering 3D-ICs, TSVs, system scaling and integration, and interconnect in conjunction with the SEMI Technology Symposium (STS).

SnZnInAg patent from Matsushita

espacenet : A solder alloy based on an Sn-Zn-In-Ag system contains, in weight, 3.0%<Zn<5.0%, 0.1%<In<4.0%, 0.1%<Ag<0.4%, and the balance Sn. Therefore, the current Sn-Pb soldering method can be employed as it is. Further, a Pb-free solder material having a solder characteristic with excellent bonding strengths of the parts can be provided. Still further, since a difference between a solidus temperature and a liquidus temperature is small, floating of the parts leads can be suppressed, even in case where packaging processes are performed many times over. Still further, when the joint is exposed to the high temperature and high humidity atmosphere, the bonding strength can be prevented from being lowered.

Matsushita patent: TWI301854 (B) ― 2008-10-11

Mixed alloy paste patent Senju

espacenet: A solder paste using a Sn-Ag base, Sn-Cu base, or similar alloy powder has a high melting point, so it causes thermal damage to electronic devices. Sn-Ag-In base lead-free solder alloys having a low melting temperature have been studied, but they are difficult to use because they cause much occurrence of chips standing up during reflow. The present invention forms a solder paste by separating a Sn-Ag-In base lead-free solder into first and second solder alloy powders for which the difference in their peak temperatures measured by differential thermal analysis is at least 10 DEG C and blends the mixed powders with a flux.

Senju patent: TWI308510 (B) ― 2009-04-11

BiZnCu solder patent Sumitomo

espacenet: Disclosed is a Pb-free solder alloy for use under high-temperature conditions, which has strength at a level required for the bonding between an electronic component and a substrate and also has excellent wettablity and processability. Specifically disclosed is a Pb-free solder alloy for use under high-temperature conditions, which comprises 0.4 to 13.5 mass% inclusive of Zn, 0.05 to 2.0 mass% inclusive of Cu, not more than 0.500 mass% of P, and a remainder made up by Bi and unavoidable impurities. The Pb-free solder alloy may additionally contain 0.03 to 0.7 mass% inclusive of Al.

Sumitomo patent: WO2012002147 (A1) ― 2012-01-05

BiSn + Sb/Ag Solder patent Senju

espacenet: A high-temperature solder alloy comprising a Bi-Sn-based solder alloy containing 90 mass% or more of Bi, wherein the Bi-Sn-based solder alloy additionally contains 1 to 5 mass% of Sn and 0.5 to 5 mass% of at least one element selected from Sb and/or Ag, and more preferably additionally contains 0.0004 to 0.01 mass% of P.

Senju patent: WO2012002173 (A1) ― 2012-01-05

SnNi solder for flip chip bonding

espacenet: Solder used for flip chip bonding inside a semiconductor package was a Sn-Pb solder such as a Pb-5Sn composition. Lead-free solders which have been studied are hard and easily form intermetallic compounds with Sn, so they were not suitable for a flip chip connection structure inside a semiconductor package, which requires stress relaxation properties.

This problem is dissolved by a flip chip connection structure inside a semiconductor package using a lead-free solder which is characterized by consisting essentially of 0.01 - 0.5 mass percent of Ni and a remainder of Sn. 0.3 - 0.9 mass percent of Cu and 0.001 - 0.01 mass percent of P may be added to this solder composition.

Senju Patent: KR20110010695, 2011-02-07

Characteristics of solderable electrically conductive adhesives (ECAs) for electronic packaging

Scopus: This study investigated the effect of the viscosity of the ECAs using a low-melting-point alloy (LMPA) filler on its bonding characteristics. The curing behaviors of the ECAs were determined using Differential Scanning Calorimetry (DSC), and ECA temperature-dependant viscosity characteristics were observed using a torsional parallel rheometer. The wetting test was conducted to investigate the reduction capability of ECAs and the flow-coalescence-wetting behavior of the LMPAs in ECAs. Electrical and mechanical properties were determined and compared to those with commercial ECAs and eutectic tin/lead (Sn/Pb) solder.

In the metallurgically interconnected Quad Flat Package (QFP) joint, a typical scallop-type Cu-Sn intermetallic compound (IMC) layer formed at the upper SnBi/Cu interface after curing process. On the other hand, a (Cu, Ni)6Sn5 IMC layer formed on the SnBi/ENIG interface. In addition, the fracture surface exhibited by cleavage fracture mode and the fracture was propagated along the Cu-Sn IMC/SnBi interface. The extremely low-level viscosity of ECAs had a significant influence on the flow-coalescence-wetting behavior of the LMPAs in ECAs and also on the interconnection properties. Stable interconnected assemblies showed good electrical and mechanical properties

Effect of reflow soldering process on metallurgical bonding between Sn3.5Ag solder and ENIG substrates

Scopus: Reflow soldering process is one of the important steps in the manufacturing process for ball grid arrays. The purpose of this study is to observe the metallurgical bonding between Sn3.5Ag solder ball and electroless nickel immersion gold (ENIG) substrates after reflow soldering process.

The reflow soldering process was performed at peak temperatures Tpeak of 246 and 251'C for 50 s by the rapid thermal processing system. Visual micrographs of these solder joints were performed in order to support the metallurgical bonding of Sn3.5Ag solder ball and ENIG substrate after the reflow soldering process.

The formation of Ni3Sn4 intermetallic compounds (IMCs) at the Sn3.5Ag solder/Ni interface was dependent and continuous with one another compared to the initial IMC formation at Tpeak of ̃246�C. It was also found that the initial IMCs thickness of Sn3.5Ag solder/Ni interface was lower and thinner at Tpeak of y251uC during the reflow soldering process.

As a conclusion, the metallurgical bonding between Sn3?5Ag solder/ENIG substrate was formed better at Tpeak of ̃251�C during the reflow soldering process using the rapid thermal processing system.

Muhammad, N.A.a , Bais, B.H.a , Ahmad, I.b , Isnin, A.c

a Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built, Environment, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Malaysia

b Department of Electronics and Communication, College of Engineering UNITEN, km 7, Jln Kajang-Puchong, Kajang 43009, Malaysia

c AMREC, SIRIM Berhad, Lot 34, Jln Hi-Tech 2/3, Kulim Hi-Tech Park, Kulim 09000, Malaysia

On the effects of temperature on the drop reliability of electronic component boards

Scopus: The effects of package temperature on failure mechanisms and lifetimes under mechanical shock loading were studied with the help of five different types of high-density packages (a WL-CSP and four CSP-BGAs) assembled on both double-layer and multi-layer FR4 boards. The localized heating of the packages by means of integrated heating elements was utilized in order to produce similar hot spots to those occurring in products in service. The results showed that the temperature can have a significant effect on the lifetimes of component boards under mechanical shock loading but that the effect varied according to the structures of the component boards. The average number of drops to failure of the WL-CSP component boards increased significantly with an increase in the temperature of the package, while the average number of drops to failure of the CSP-BGA component boards generally decreased. On the other hand, the drop reliability of one out of four CSP-BGA component board types was insensitive to temperature.

The failure modes and mechanisms were clarified with the help of physical failure analyses that revealed different failure modes in the component boards. Furthermore, depending on the component board type, the primary failure mode may change with temperature from that identified at room temperature. Particular attention was paid to the nucleation and propagation of cracks at different test temperatures. Computational case studies were designed in order to identify the significance of a change in temperature on three factors: (a) the stiffness of the PWB; (b) the strength and elastic modulus of the solder, and (c) the thermomechanical loads. The influences of each factor on the strains and stresses in the proximity of the solder interconnections were evaluated by means of the finite element method. The results of the statistical and physical failure analyses were rationalized with the help of the results from the finite element analyses. They showed that the effects of a change in temperature on the lifetimes of the component boards under mechanical shock loading can be explained by changes in the nucleation site and/or the propagation of cracks. The results presented in this paper point out that single-load reliability tests can form an incomplete understanding of the failure mechanisms in real service environments and modifications to the currently employed reliability test standards that are needed

Mattila, T.T. , Li, J., Kivilahti, J.K.

Department of Electronics, Helsinki University of Technology, 02015 TKK, Finland

Influence of trace alloying elements on the ball impact test reliability of SnAgCu solder joint

Scopuss: In this work, we present ball impact test (BIT) responses and fracture modes obtained at an impact velocity of 0.8 m/s on SAC (Sn-Ag-Cu) package-level solder joints with a trace amount of Mn or RE (rare earth) additions, which were bonded with substrates of OSP Cu and electroplated Ni/Au surface finishes respectively. With respect to the as-mounted conditions, the Ni/Au joints possessed better impact fracture resistance than those with Cu substrate.

Subsequent to aging at 150'C for 800 h, multi-layered intermetallic compounds emerged at the interface of the Ni/Au joints and gave rise to degradation of the BIT properties.

This can be prevented by RE doping, which is able to inhibit the growth of interfacial IMCs during aging.

As for aged Cu joints, the Mn-doped samples showed the best performance in impact force and toughness. This was related to the hardened Sn matrix, and most importantly, a greater Cu3Sn/Cu6Sn5 thickness ratio at the interface. Compared to Cu6Sn5, Cu3Sn with a similar hardness but greater elastic modulus possessed better plastic ability, which was beneficial to the reliability of solder joints suffering high strain rate deformation if no excess Kirkendall voids formed

A review on thermal cycling and drop impact reliability of SAC solder joint in portable electronic products

Scopus: Currently, the portable electronic products trend to high speed, light weight, miniaturization and multifunctionality. In that field, solder joint reliability in term of both drop impact and thermal cycling loading conditions is a great concern for portable electronic products.

The transition to lead-free solder happened to coincide with a dramatic increase in portable electronic products. Sn-Ag-Cu (SAC) is now recognized as the standard lead free solder alloy for packaging interconnects in the electronics industry. The present study reviews the reliability of different Ag-content SAC solder joints in term of both thermal cycling and drop impact from the viewpoints of bulk alloy microstructure and tensile properties.

The finding of the study indicates that the best SAC composition for drop impact performance is not necessarily the best composition for optimum thermal cycling reliability. The level of Ag-content in SAC solder alloy can be an advantage or a disadvantage depending on the application, package and reliability requirements. As a result, most component assemblers are using at least two (and in many cases even more) lead-free solder sphere alloys to meet various package requirements

Shnawah, D.A. , Sabri, M.F.M., Badruddin, I.A.

Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia

Microelectronics Reliability

Volume 52, Issue 1, January 2012, Pages 90-99

Speedprint Reports Strongest Year

EMSNow: Speedprint's results have been fuelled by the increasing focus of customers on excellence in print quality combined with value for money.

In 2011 Speedprint entered the North American market with a direct operation headed by Mark Brawley, Speedprint Americas VP of Sales. The introduction of Speedprint in the United States is already ahead of the company's plans and continues to grow in momentum.

At the same time, the success of the Speedprint products generally is generating increasing interest from China where the company has yet to establish a dedicated sales channel.

Military/Aerospace Lead-Free Solder Reliability Still Unproven

Ron Lasky Indium Blog 
Indium colleague Ed Briggs and I gave a 3 hour presentation on “Lead-Free Assembly for High Yields and Reliability.” I think Ed’s analysis of “graping” and the “head-in-pillow” defect is the best around.

There was quite a bit of discussion on the challenges faced by solder paste flux in the new world of lead-free solder paste and miniaturized components (i.e. very small solder paste deposits.) One of the hottest topics was nitrogen and lead-free SMT assembly. There seemed to be uniform agreement that solder paste users should be able to demand that their lead-free solder paste perform well with any PWB pad finish (e.g. OSP Immersion silver, electroless nickel gold, etc.) without the use of nitrogen. Not only does using nitrogen cost money, but it will usually make tombstoning worse. However, in the opinion of most people, nitrogen is a must for wave soldering and, since it minimizes dross development, it likely pays for itself.

After Ed and I finished, Fred Dimock, of BTU, gave one of the best talks I have ever experienced on reflow soldering. He discussed thermal profiling in detail, including the importance of assuring that thermocouples are not oxidized (when oxidized they lose accuracy). He also discussed a reflow oven design that minimizes temperature overshoot during heating, and undershoot when the heater is off. Understanding these topics is critical with the tight temperature control that many lead-free assemblers face.

Fred Verdi of ACI finished the meeting with an excellent presentation on “Pb-free Electronics for Aerospace and Defense.” Fred’s talk discussed the work that went into the “Manhattan Project.” A free download of the entire project report is available.

There appears to be agreement that acceptable lead-free reliability has been established for consumer products with lifetimes of 5 years or so, but not for military/aerospace electronics where lifetimes can be up to 40 years in harsh service conditions. These vast product lifetime and consequences of failure differences are depicted in the Fred's chart (above). Commercial products are in quadrant A and military/aerospace products in quadrant D.

One of the greatest risks faced by quadrant D products is tin whiskers. Fred spent quite a bit of time discussing this interesting phenomenon. One of the challenges of this risk is that there is no way to accelerate it, so you can’t do an equivalent test to accelerated thermal cycling or drop shock. Fred mentioned that there have now been verified tin whisker fails, the Toyota accelerator mechanism being a confirmed one.

In addition to tin whiskers, lead-free reliability for quadrant D products (with a service life of up to 40 years) in thermal cycle and other areas remains a concern.  I mention that tin pest was not on the list of issues for this quadrant.

Fred and the Manhattan Project Team have identified many "gaps" that need to be addressed to determine and mitigate the risk of lead-free assembly for quadrant D products.  They plan to start this approximately $100M program in 2013.

For those that missed this free workshop, ACI host Mike Prestoy is planning another one in 6 months.



Read more: http://blogs.indium.com/blog/an-interview-with-the-professor/militaryaerospace-lead-free-reliability-still-unproven#ixzz1ihiB0lvL

Pb-Free Sn-Ag-Cu-Al or Sn-Cu-Al Solder

US20110303448A1: A solder alloy includes Sn, optional Ag, Cu, and Al wherein the alloy composition is controlled to provide a strong, impact-and thermal aging-resistant solder joint that has beneficial microstructural features and is substantially devoid of Ag3Sn blades.

Anderson, Iver E.; Ames, IA, United States of America

Harringa, Joel L.; Ames, IA, United States of America

Boesenberg, Adam J.; Ames, IA, United States of America

Assignee: Iowa State University Research Foundation, Inc.

Reliability of SnAgCu solder joints during vibration in various temperature

Scopus: The results of study focused on reliability of SnAgCu/ImSn (1206 and 0805 SMD) solder joints subjected to vibration in various but constant temperature (-40 and 130) will be presented.

The results will be also compared with the results of author's previous reliability tests focused on reliability of SnAgCu solder joints subjected to vibration combined with temperature cycles. Time to failure will be measured using dedicated event detector. After the tests solder joints will be inspected using ultra high-resolution nanofocus X-ray inspection system and nanoCT

Matkowski, P.

Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Wroclaw, Poland

34th International Spring Seminar on Electronics Technology: "New Trends in Micro/Nanotechnology", ISSE 2011; Tratanska Lomnica; 11 May 2011 through 15 May 2011; Category number CFP11509-ART; Code 87529

Long-term behavior of IMCs in lead-free solder joints

Scopus: This article deals with the creation and growth of intermetallic compounds (IMCs) in solder joints. The test specimens of copper substrate were made for this experiment. The soldered joints were created on the test specimens by hand soldering process at the temperature of 250'C.

Four lead-free solder alloys and one tin-lead solder alloy were chosen for research of IMCs. The test specimens were divided into several groups. These groups differ in two parameters. The first parameter is soldering process, concretely soldering time. Half of the specimens were soldered for a period of 10 seconds and the second half of specimens were soldered for a period of 60 seconds. The second parameter is a thermal stress. The test specimens were exposed to elevated aging for research of long-term behavior of IMCs in solder joint. The specimens were thermal stressed in hot air oven at the temperature of 150'C for a periods of 4, 8, 12, 16 and 20 weeks. The results of analysis of IMCs in solder joints using confocal and metallographic microscopes are presented in this article

Novak, T., Hujer, T., Steiner, F.

Department of Technologies and Measurement, Faculty of Electrical Engineering, University of West Bohemia in Pilsen, Pilsen, Czech Republic

34th International Spring Seminar on Electronics Technology: "New Trends in Micro/Nanotechnology", ISSE 2011; Tratanska Lomnica; 11 May 2011 through 15 May 2011; Category number CFP11509-ART; Code 87529

Properties of the SAC solder paste with different nanoparticles

Scopus Our research objective is trying to mofy the SAC solder paste properties by addition a different nanoparticles. It is continuation of our previous work on including to the SAC solder paste the silver nanoparticles with different grain sizes. Improvement of the wetting results of investigated "nano solder pastes" on copper substrate depends especially for the 4% silver nanopowders. It forced us to enlarge our work on nickel and copper nanoparticles. The SAC "nanopastes" were obtained by adding from 0.05 to 4% of Ni, Cu and Ag nanoparticles. The results were compared with previously obtained for SAC with silver nanoparticles. We measured spreading, wettability, solder ball and slump of the "nanopastes". We obtained contrary results of wettability for nNi and nCu addition than for the silver nanoparticles addition. Wetting of the SAC solder paste with nNi and nCu decreases with increasing of the nanoparticles addition. Using SEM and EDS spectroscopy we measure the "nanosolder" pastes microstructure for establishing the differences between type of nanoparticles and their amount added to SAC solder paste. The microstructure of the cross-sectional solder joints as well as creates the IMC scallop or rod layers with different thickness after reflow process will be presented.


34th International Spring Seminar on Electronics Technology: "New Trends in Micro/Nanotechnology", ISSE 2011; Tratanska Lomnica; 11 May 2011 through 15 May 2011; Category number CFP11509-ART; Code 87529


Bukat, K.a b , Kościelski, M.a b , Sitek, J.a b , Jakubowska, M.a b c , Młozniak, A.c  
a  Tele and Radio Research Institute, Warsaw, Poland
b  Warsaw University of Technology, Warsaw, Poland
c  Institute of Electronic Materials Technology, Warsaw, Poland

Test of wettability of lead-free solders

Scopus: This paper deals with wettability of widely used lead-free solders. Tested solders were lead-free solders Sn-3,8Ag-0,7Cu, Sn-4Ag, Sn-1Cu and Pb containing solder Sn-37Pb. Wetting balance method was used for testing wettability of the solders mentioned above according to standard ČSN EN 60068-2-54.

Temperature of melted solder was 235'C for Sn-37Pb and 248'C for lead-free solders. Wetting was tested for copper and nickel in form of wire with diameter 1 mm and length 20 mm. Samples were dipped into melted solder and total force actuating in time during the test was measured. Key parameters for characterization wetting behavior of solder were maximum wetting force and the time to reach 2/3 of that force. The influence of nitrogen atmosphere was tested as well.

Podzemský, J., Urbánek, J.

Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic

Proceedings of the International Spring Seminar on Electronics Technology

2011, Article number 6053549, Pages 53-56

Molex Introduces New CMC Standard Header and Solder-Mount Headers with Press-Fit Terminals

Factiva: The new 154-circuit, three-pocket, right-angle header with compliant-pin terminals improves productivity and reduces assembly costs by enabling a solder-free process, as opposed to conventional press-fit type mounting processes. The 154-circuit header features 120 x 0.635mm (.025’) signal pins, 24 x 1.50mm (.059’) terminals and 10 x 2.80mm (.110’) power pins, supporting high currents in applications such as large ECUs. The sophisticated and robust design of the integral guiding plate protects the 5 terminal rows and ensures positioning, while being able to withstand high-vibration levels up to 10G. Ideal for heavy-duty agricultural equipment applications, the 154-circuit connection system performs up to 50 mating cycles for mating and unmating of multiple ECUs on different applications

Method for high-temperature circuit board assembly

US20110308847 (The creation of a circuit board which contains electrical interconnections between the circuit board traces and electronic devices mounted on the circuit board where the circuit board assembly can be operated at temperatures of 600' C. or greater. This invention allows for solder connections to be formed using solder paste or high-temperature.

Parent Case: PRIORITY
The present application claims priority from commonly owned and assigned provisional application by Randy A. Normann, entitled “Method for High-Temperature Circuit Board Interconnects” sent in to the Commissioner of Patents, PO Box 1450, Alexandria, Va. on May 18, 2010. This document is incorporated herein by reference.



First Claim:
1. A method for circuit board assembly where electrical connections between conductors on a circuit board are created in recesses in the insulating material of the circuit board to contain the solder paste when creating a solder joint between the conductors.

Normann, Randy Allen; Edgewood, NM, United States of America

Assignee: None

Published / Filed: 2011-12-22 / 2010-06-21

Temperature cycling reliability of high-temperature lead-free die-attach technologies

Scopus: The demand for electronics capable of operating at temperatures above the traditional 125 'C limit continues to increase. Devices based on wide bandgap semiconductors have been demonstrated to operate at temperatures up to 500 'C, but packaging remains the major hurdle to product development.

Recent regulations, such as RoHS and WEEE, increase the complexity of the packaging task by prohibiting the use of certain materials, such as lead, in electronic products. Traditionally, lead has been widely used in high-temperature solder attach. In this paper, a series of Pb-free die-attach technologies have been identified as possible alternatives to Pb-based ones for high-temperature applications.

This paper describes the fabrication sequence for each system and assesses their long-term reliability using accelerated thermal cycling and physics-of-failure modeling.

The reliability of the lead-rich alloy was confirmed during this investigation, while early failures of the silver-filled epoxy demonstrated their inability to survive high temperatures. An empirical damage model was developed for the silver nanoparticle paste based on fatigue induced failures.

Encouraging reliability data have been presented for the gold-tin solid-liquid interdiffusion system where bond quality was demonstrated to be a critical factor in its failure mode and mechanism.

Quintero, P.O.a , McCluskey, F.P.b

a Department of Mechanical Engineering, University of Puerto Rico-Mayaguez, Mayaguez, 00681, Puerto Rico

b CALCE, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, United States

IEEE Transactions on Device and Materials Reliability

Volume 11, Issue 4, December 2011, Article number 5744108, Pages 531-539

Special Lead-Free Issues of J Material Science

Journal of Materials Science: Materials in Electronics
2011, Page 1
 Article in press  
ISSN: 09574522
DOI: 10.1007/s10854-011-0593-5
Document Type: Article in Press
Source Type: Journal


View at publisher|

Featured issue: Lead-free solder and packaging

Willoughby, A.

Was Lead-Free Solder Worth the Effort?

ECN: Electronic Component News: To delve deeper into the need for lead-free solder I talked with a knowledgable person at the IPC, formerly know as the Institute for Interconnecting and Packaging Electronic Circuits. When I asked about any follow-up studies that could show the benefits of lead-free solder, the spokesperson explained that such studies would simply waste money because they would show no changes in lead exposure in landfills and no changes in occupational exposure, either. Years ago companies recognized the dangers of lead exposure and took measures to protect employees. The problems in third-world salvage yards stem from improper waste management.

The IPC person also explained the EPA produced an overall hazard assessment that included aspects such as ozone depletion and global warming and did not provide an exposure assessment. So far, the EPA has done no additional research to determine the effects of eliminating lead from solder.

In the end, though, lead-free solder proved beneficial for solder and soldering-equipment vendors, but overall, the entire effort seems like a waste of time, talent, and money.

Effects of critical parameters on solder deposition

Factiva: "The purpose of this paper is to comprehensively explore the effects of critical parameters on solder deposition and to establish a systematic approach for determining guidelines for solder paste inspection (SPI) workstations. Design/methodology/approach - This study explored the effects of process parameters, stencil and printed circuit board designs on solder deposition and identified the major post-reflow defect scenarios," scientists in Taipei, Taiwan report.

Bi-Al-Zn-BASED Pb-FREE SOLDER ALLOY

WO2011158668 Disclosed is a Pb-free solder alloy with low residual stress at solidification and high bonding strength and reliability, that can suppress Ni-Bi reaction and Ni diffusion when an electronic component that includes Ni and a substrate are bonded, and that can withstand high reflow temperatures. A first Pb-free solder alloy contains 0.03% to 0.70% by mass Al and 0.2% to 14.0% by mass Zn, and the balance, excluding unavoidable impurities, is formed from Bi. A second Pb-free solder alloy contains 0.03% to 0.70% by mass Al and 0.2% to 14.0% by mass Zn, does not contain more than 0.500% by mass P, and the balance, excluding unavoidable impurities, is formed from Bi.

ISEKI Takashi; Japan 〒19

 Assignee: SUMITOMO METAL MINING CO., LTD. Japan〒10
 News, Profiles, Stocks and More about this company

 Published / Filed: 2011-12-22 / 2011-06-03

 Application Number: WO2011JP0062792

Lead-free Solder Ames Lab's Top Income-Generating Technology

SMTONLINE: Fifteen years ago, an environmentally-friendly solder developed by the U.S Department of Energy’s Ames Laboratory made history as the first cost-effective, broadly useable alternative to tin-lead solder, a toxic but necessary ingredient in a range of popular – and proliferating – consumer electronics.

ImageNow lead-free solder, a tin-silver-copper alloy invented by a research team headed by Ames Lab senior metallurgist Iver Anderson, has made history for a second time: In 2011, it became the top royalty income-generating technology ever produced in the history of both Ames Lab and Iowa State University.

In earning this distinction, lead-free solder surpassed Ames Lab’s previous top royalty earner – a mass spectrometer that combines the key analytical tools of multiplexed capillary electrophoresis with inductively coupled plasma-mass spectrometry – and ISU’s longstanding record-holder: an algorithm, patented in 1972, that expedited the fax transmission process.

“As of the end of June 2011 lead-free solder generated $38.9 million in royalties, exceeding all other licensed ISU technologies,” said Nita Lovejoy, associate director of the ISU Research Foundation (ISURF) and ISU's Office of Intellectual Property and Technology Transfer. Through its contract with the DOE to operate the lab, ISU may retain rights to Ames Laboratory funded intellectual property.

Long Term Reliability Analysis of Lead Free and Halogen Free Electronic Assemblies

The New England Lead Free Consortium, composed of many companies in the electronic supply chain in the regional area and chaired by the author; has embarked on an extensive long term reliability study of lead-free and halogen free electronic assemblies. Specialized PCB’s were built, assembled and reworked at the consortium member companies using multiple types of laminates, PCB surface finishes and various component types including through-hole and surface mount technology. The assemblies were examined for visual characteristics and subsequently tested for reliability using temperature cycling as well as vibration testing. All rework, reliability tests, and evaluations have used or will be using industry standards, methods and techniques for easy reference to other long term reliability studies. The studies will include comparison to a baseline of leaded electronic assemblies. This paper will outline results obtained so far into the long term reliability study.

APEX 2009 Paper

Effect of Lead-Free on Key Material Properties of Laminates

The high temperature exposures associated with lead-free soldering of printed circuit boards (PCBs) can alter the laminate material properties thereby creating a shift in the performance and reliability of the PCB and entire electronic assembly. The knowledge of PCB laminate material properties and their dependence on the material constituents, combined with their possible variations due to lead-free soldering exposures, is an essential input in the selection of laminates for appropriate applications.

An experimental study is conducted on fourteen types of commercially available PCB laminate materials to assess the effects of lead-free soldering process on key thermomechanical and physical properties. The laminates are classified on the basis of their glass transition temperature (high, mid and low), type of curing agents (dicyandiamide (DICY) and phenolic), type of flame retardants (halogenated and halogen-free), and presence or absence of fillers. Laminate material properties [glass transition temperature (Tg), coefficient of thermal expansion (CTE), decomposition temperature (Td), time-to-delamination (T-260), and water absorption] are measured as per the appropriate IPC-TM-650 test methods before and after subjecting to multiple lead-free soldering cycles (namely, three reflow cycles, six reflow cycles, and a combination of one wave and two reflow cycles).

The lead-free soldering exposures resulted in variations in the material properties of certain FR-4 laminate material types.

The extent of variations in the thermomechanical and physical properties under investigation are discussed as a function of material constituents. It was found that the type of curing agent has a more pronounced effect on the response of materials to exposures than the type of flame retardant or presence of fillers. For example, a significant variation in the Tg and CTE of certain DICY-cured materials is observed after the exposures. Also, time-to-delamination of DICY-cured materials decreased whereas phenolic-cured materials could retain their thermal stability even after exposures. An increase in water absorption after the exposures is observed in most of the materials. The exposures did not affect the laminate materials to an extent of changing their decomposition temperatures.


Paper APEX 2009 

Special edition of Mat Trans on Lead-Free for November 2012

From: Katsuaki Suganuma [mailto:suganuma@sanken.osaka-u.ac.jp]
Sent: 11 November 2011 04:51
To: suganuma@sanken.osaka-u.ac.jp
Subject: Submission invitation to MaterTrans special issue on lead-free and advanced interconnection

Dear Sir:

We are happy to inform you that our journal Materials Transactions (The Japan Institute of Metals) will publish a special issue on Lead-Free and Advanced Interconnection Materials for Electronics V as November 2012 .
You will find the announcement on the issue and the instruction of preparation in the following.

Announcement:10 years have passed since lead-free transition in electronics 　
                        interconnection. Lead-free interconnection has become one
                        of the indispensable technologies not only in consumer
                        electronics industries but also wider areas including
                        automotive, power electronics, aeronautic, LED lighting
                        and renewable energies, in which higher reliability
                        becomes essential. In addition, ultra heat-resistant
                        interconnection materials beyond 200 oC are required for
                        the establishment of wide band gap semiconductors such as
                        SiC and GaN. Those interconnection materials will involve
                        high temperature lead-free solders, conductive adhesives,
                        nano/micron particle sintering bonding, and nano solders.
                        In the current 5th special issue, the papers focused on
                        new interconnection materials are widely invited. New
                        scientific findings and technology development will be
                        demonstrated. Thus, this special issue will provide great
                        insight to the readers working in the field of the
                        advanced interconnection engineering.

Topics: Tin whisker, Electromigration, High temperature solder alternatives,
　　　　Conductive adhesives, Die-attach, TSV, wafer bonding, Plating,
            Microstructure and phase stability, Interface reactions, Reliability,
            Mechanical properties of solders and joints, Wetting phenomena,
            Corrosion, oxidation and ion-migration, Soldering processes and
            fine pitch assembly, Materials in soldering process, Environmental
            impacts and recycling

Instruction of preparation

Bylaws for Contribution to Materials Transactions http://www.sendai.kopas.co.jp/METAL/rule.html

Manuscript Instructions
http://www.sendai.kopas.co.jp/METAL/point.html

Application form
http://jim.or.jp/cgi-bin/jim/kaigaieentry.cgi

We would be very pleased if you would contribute an original paper (Regular Article) to the issue.

Contributors will bear part of the cost for publication. Contributors will be presented 50 reprints free.

Please register in the Application Form Page if you will contribute your paper.

Manuscripts due is June 1, 2012.


Sincerely yours,

Prof. S. Miyazaki
Chairperson
Mater. Trans.
FAX:   +81-22-223-6312
E-mail: editjt@jim.or.jp

iNEMI Kicks off 2013 Roadmap

Word versions of 2011 TWG chapters and the Executive Summary will be sent to all TWG Chairs on or about January 4 for use in preparing the 2013 version. An organizing teleconference with TWG Chairs will be held on January 11. Additionally, a teleconference for the iNEMI Technical Committee and PEG Chairs is scheduled for January 13 to review the status of the PEG emulators. Any TWG that would like to meet at APEX prior to the Kick-Off Workshop should contact  Chuck Richardson regarding meeting room availability.

Website with Schedule

Seeking Consensus for Lead-Free

Ron Lasky looking for inputs on lead-free challenges for his blog

Real Time With... SMTAI 2011

e-Book collection on lead-free technologies

Website

IPC SPVC Round Robin study on alternative alloys

Background - IPC White Paper July 2011


Auburn test - a test mthod is being recommended
Work with iNEMI
Reliability experts - buy-in
Categorisation - not pass-fail

Video interview

RoHS Recast consultant study

Bio Intelligence service and ERA commissioned to do RoHS2 recast impact assessments etc

December - list of impact assessments published

Project Website

IPC China 2012

The year 2012 happens to be the 10th Anniversary of IPC China established, besides the technical conference week of CEMAC held annually in May in Shanghai and WorksAsia held annually in October in Shenzhen, IPC China plans to organize tour technical conferences in such cities as Beijing ,Qingdao , wuhan, Suzhou , xi’an, Chengdu ,aiming at providing more convenient services to the electronics industry and technical professionals. All conferences will be held on the exhibition held at the same time at the respective cities , and the tenth anniversary celebration of IPC China will be put on ,too.

IPC China sincerely invites you participate in IPC China Technical Conferences to share your technical achievement and experiences on IPC China，a platform serving all companies of the electronic manufacturing industry.

Topics will cover the latest fields such as advanced technology, materials, EMS，process, design, and environment, etc.

Deadlines for Abstract & Speaker Bio. and slides of presentation submission:

Conference City Date Content Deadline of Abstract Deadline of slides of presentation

CEMAC shanghai 2012.05 Conference paper(within 50 minutes) 

workshop（above 2hours ） 2012.02.20 2012.04.05

WorksAsia shenzhen 2012.10 Conference paper(within 50 minutes) 

workshop（above 2hours ） 2012.07.20 2012.09.10

Tour conference beijing 2012.05 Conference paper(within 50 minutes) 2012.02.15 2012.04.20

Suzhou 2012.05 Conference paper(within 50 minutes) 2012.02.15 2012.04.20

chengdu 2012.06 Conference paper(within 50 minutes) 2012.03.15 2012.05.20

qingdao 2012.07 Conference paper(within 50 minutes) 2012.04.20 2012.06.10

Xi’an 2012.09 Conference paper(within 50 minutes) 2012.06.20 2012.08.10

wuhan 2012.11 Conference paper(within 50 minutes) 2012.08.15 2012.10.01

 

Thank you for your support of IPC China and we look forward to your participation！

iMAPS New England – 39th Symposium & Expo

May 8, 2012
Holiday Inn – Boxborough Woods Conference Center
Boxborough, Massachusetts


Event Website

Solder Charge SMT

New design from SMT joints

Molex SMTA Paper Dec 2010

IPC Conference on Electronics Assembly: Soldering, Assembly & Inspection

20–22 March 2012 | Budapest, Hungary | Ramada Resort Aquaworld

Event website

EMPC 2012 & MiNaPad

Organised by IMAPS France

EMPC 2012 & MiNaPad Website