IMAPS 2010, Raleigh/RTP - Technical Program (Sessions)

IMAPS 2010: "TP4
Pb-Free Solder Materials and RoHS, Processes and Reliability
Chairs: Young-Bae Park, Andong National University; Tae-Kyu Lee, Cisco Systems, Inc.; Jae-Woong Nah, IBM T. J. Watson Research Center

This session provides the latest advances in materials, processes, and reliability issues in Pb-free solder materials.

Pb-Free v/s Tin-Lead Reliability Comparison for Telecom/High Reliability Applications
Ganesh Iyer, Gnyaneshwar Ramakrishna, Lavanya Gopalakrishnan, Kuo-Chuan Liu, Cisco Systems, Inc.

Effects of Fe on the Kirkendall Void Formation of Sn-3.5Ag-xFe/Cu Solder Joints
Sunghwan Kim, Jin Yu, KAIST

Impact of Isothermal Aging on Fine Pitch BGA Packages with Sn-Ag-Cu Solder Interconnects
Tae-Kyu Lee, Weidong Xie, Bite Zhou, Thomas Bieler, Kuo-Chuan Liu, Jie Xue, Cisco Systems, Inc.

A Study on Black Pad Phenomenon in Electroless Ni(P) Films
J.H. Kim, K. H. Kim, Jin Yu, KAIST

Nanoindentation Characterization of Lead-free Solders and Intermetallic Compounds Under Thermal Aging
Shi-Wei Ricky Lee, Tong Jiang, Fubin Song, Chaoran Yang, HKUST

The Electromigration (EM) Induced Voids Evolution in Sn-3.5Ag/Cu Solder Joint Under Current Stressing
Yong Jung, Jin Yu, KAIST"

Technical Conference on Electronics Sustainability | IPC Midwest 2010

IPC Midwest 2010: "This conference has been created to meet the needs of the electronics manufacturing industry in the Midwest. Today’s focus on reliable, sustainable products that meet customer needs without failure during the product’s life cycle brings new challenges to the supply chain. Sessions on advances in printed board design and fabrication focusing on HDI/microvia technology and surface finishes, the latest assembly processes and materials, end-product sustainability, and design for reliability through failure analysis will help you assure quality throughout your product’s manufacture and use."

China RoHS to cover all products

DfR Solutions Newsletter, July/August 2010
The Chinese Ministry of Industry and Information Technology (MIIT) has released a new general requirements document for China RoHS. The biggest changes? The scope has broadened from Electronic Information Products listed in a catalog to any Electronic and Electrical Products powered below 1500 VDC or 1000 VAC. In addition to the restricted six (Hg, Pb, Cd, Hex Cr, PBB, PBDE), there is the possibility of "State regulations of other harmful substances" and inspection will be performed at both entry AND exit and items will be subject to quarantine (say goodbye to the building of SnPb electronics in China).

The profileration of lead-free alloys

Realtime with IPC: Video with Ron Lasky and Jaspir Bath

IPC, IPCA Comment on India's Proposed E-Waste Rules

EMS007 : "Working together to address the latest round of proposed substance restrictions, IPC and the Indian Printed Circuits Association (IPCA) have submitted comments in response to the Indian Government's Ministry of Environment and Forests draft notification of E-waste (Management and Handling) Rules 2010. Specifically, IPC is concerned that the proposed Chapter V, Reduction in the use of hazardous substances (RoHS) in the manufacture of electrical and electronic equipment will have a negative impact on the global and Indian electronics industry and will fail to accomplish the Ministry's goal of environmentally sound management of electrical and electronic equipment waste."

Effects of nano-Al2O3 additions on microstructure development and hardness of Sn3.5Ag0.5Cu solder

Scopus: "This work investigates the effects of nano-Al2O3 on the microstructure and microhardness of the Sn3.5Ag0.5Cu composite solder alloy. In comparison with solder without the addition of nano-Al2O3 particles, the formation of primary β-Sn phase, the Ag3Sn phase average size, and the spacing lamellae decreased significantly in the composite solder matrix."

In addition, the eutectic areas of the composite solder were wider than that of the Sn3.5Ag0.5Cu solder. This is attributed to the adsorption of nano-Al2O3 particles with high surface free energy on the grain surface during solidification. The wettability property was improved by 0.25-0.5wt.% addition of nano-Al2O3 particles into the Sn3.5Ag0.5Cu solder. However, when the nano-Al2O3 particles concentration up to over 1.0wt.% decreased the beneficial influence. Microhardness improved with the addition of nano-Al2O3 particles. This improved mechanical property was due to the composite microstructure, which is close to the theoretical prediction from dispersion strengthening theory.

Tsao, L.C.a , Chang, S.Y.b , Lee, C.I.a , Sun, W.H.a , Huang, C.H.c

a Department of Materials Engineering, National Pingtung University of Science and Technology, Neipu, Pingtung 91201, Taiwan

b Department of Mechanical Engineering, National Yunlin University of Science and Technology, 64002 Touliu, Yunlin, Taiwan

c Metal Industries Research and Development Centre, 81160 Kaohsiung, Taiwan

Scopus - ASME Recrystallization of lead free solder joints - confounding the interpretation of accelerated thermal cycling results?

Scopus: "A primary concern of any reliability engineer is whether failure in accelerated testing may be caused by a different damage mechanism than the one that determines life in service. The recent suggestion that thermal expansion mismatch induced fatigue and failure of lead free solder joints under realistic service conditions may progress without the recrystallization seen to play a major role in accelerated thermal cycling thus requires systematic investigation. A total different concern is the ever recurring question of to which extent thermal cycling can be replaced by much faster isothermal cycling tests. The observation that the damage mechanisms tend to be completely different, one leading to transgranular cracking the other to intergranular cracking of lead free BGA solder joints, would seem to invalidate such ideas completely."

Importantly, most practical service scenarios involve the combination of more than one loading conditions. This may be as simple as thermal excursions to different temperatures or vibrations with two different frequencies or amplitudes, but it may also involve a combination of thermal excursions and vibration, for example. Reliability prediction almost invariably relies on the explicit or implicit assumption of some principle of damage accumulation, most commonly Miner's rule. These assumptions do, however, break down much more often than commonly recognized. One important reason for this, albeit clearly not the only one, would be the different effects of recrystallization. All of these concerns prompted an ongoing investigation to identify the parameters determining whether recrystallization will affect lead free solder fatigue life and what would be the practical consequences.

Reliability the Focus at AREA Consortium Meeting

Circuits Assembly "A look at the overall robustness and reliability of electronics assemblies under conditions of overstress, thermal and isothermal cycling, long-term aging, and more complex loading histories included a focus on BGA and CSP assemblies, but emphasis was placed on configurations found to behave differently.

Presentations looked at pad cratering and an analysis of intermetallic failures on electrolytic NiAu; Pb-free solder microstructure and reliability, including detailed discussions on the thermal cycling of Pb-free BGAs, TSOPs, QFNs and solder joints; thermal cycling and why TSOPs, QFNs, LGAs, and passives are all different from BGAs in this regard; and a look at the reliability of reballed components and Pb-free solder joints on ENEPIG pads."

Carboxylate-passivated silver nanoparticles and their application to sintered interconnection: A replacement for high temperature lead-rich solders

Scopuss: "Lead-free silver nanoparticle pastes have been tested as a replacement for high temperature lead-rich solders used in electronic manufacturing. The pastes contain a small amount of solvent, and primarily consist of submicron- silver powder and passivated silver nanoparticles. The nanoparticles were synthesized from Ag2CO3 and a long-chain alcohol by a method that produced a passivating layer consisting almost exclusively of the carboxylate of the reactant alcohol.

The pastes were used to connect a silicon diode chip to copper bases without applied pressure when sintered at 350'C under nitrogen. Diode packages made with sintered silver interconnects had electrical and thermal properties equal to those with lead-soldered interconnects, even after 3000 thermal cycles between -55'C and 150'C. The mechanical strength was half that of lead-rich solder joints, but still strong enough for practical use."

Role of Solder Paste in New Decade of Packaging and Assembly

SMT: "So, what is new?

First, solder paste formulation needs to embrace the deep know-how, coupled with the thorough understanding of the fundamentals, to deliver the performance requirements in the printing process. Meanwhile, there is a renewed interest in dipping techniques (equivalent to the pin transfer process used in 1980s), which require a different set of rheological attributes, as opposed to stencil printing process.

There will also be a need for mesh screen printable paste. In chemistry, halogen-free solder paste is expected to share an increased demand (in my viewpoint, halogen-free paste should have been the practice at all times.) There may be a renewed interest in vapor phase soldering, thus the solder paste for it. My workshop, 'Packaging and Assembly in the New Decade--Materials and Processes' to be held September 29, 2010 at IPC Electronics Midwest Conference in Chicago, Illinois will address these areas.

Additionally, solder paste formulations that are to be synchronized with the new lead-free alloys will continue to evolve. To achieve the necessary quality and consistence, solder paste production operation calls for tighter control going forward.

In my upcoming columns, specific solder paste material characteristics, process techniques, equipment requirements and production defects and remedies will be addressed."

2010 International Printed Circuit & Electronics Assembly Fair

2010 International Printed Circuit & Electronics Assembly Fair: "Jointly organized by the Hong Kong Printed Circuit Association (HKPCA), IPC - Association Connecting Electronics Industries and the China Council for the Promotion of International Trade Guangzhou Sub-council (CCPIT-GZ), the Fair will be held on 1-3 December 2010 at the Shenzhen Convention & Exhibition Center, China."

Creep properties of Ag nanoparticle reinforced Sn-Cu composite solders

Scopus: "Reinforced Ag nanoparticles were incorporated into Sn-0.7Cu matrix composite solder by a mechanical means in order to improve the creep properties of the solder matrix. The creep-rupture life was studied of Sn-0.7Cu solder joints and composite solder joints reinforced with Ag nanoparticles at different temperatures and applied stresses. Stress exponents and creep activation energy were calculated for Ag nanoparticle reinforced Sn-Cu matrix composite solder joints at different temperatures and stress levels.

Steady-state creep constitutive equation of the composite solder joint was established. Results show that at different temperatures and stresses, Ag nanoparticles reinforced Sn-Cu composite solder joints have higher creep rupture life and creep activation energy than Sn-0.7Cu solder joints. It indicates the creep resistance of the composite solder joint with 1 vol% Ag reinforcement addition is better than that of Sn-0.7Cu solder joint."

Tai, F., Guo, F., Shen, H., Liu, J.

Beijing University of Technology, Beijing 100124, China

Senju Manufacturing Joins HDP User Group

EMS007 : "The High Density Packaging User Group International, Inc. (HDP User Group), a global non-profit cooperative research and development organization for the Electronics Manufacturing industries, announces that Senju Manufacturing has joined the organization. Senju will participate in HDP User Group's technical programs.

The HDP organization and its member companies are excited about the addition of Senju and look forward to sharing knowledge in current and future projects that will benefit all. 'Senju, as a world leader in many of the materials used for manufacturing electronics will be a very important addition to the HDP User Group team. Often the solutions to the technical issues in electronics manufacturing derive from improved materials. We look forward to working with the Scientists and Engineers at Senju to address and solve the industry's problems,' said Marshall Andrews, Executive Director of HDP User Group International."

High Power Laser and Particle Beams: Influencing factors of lead-free laser soldering speed

Scopus: "In order to increase the lead-free laser soldering speed, the laser parameters, properties of solder and substrate, laser soldering system and other influencing factors of the lead-free laser soldering are studied.

The research shows that once the laser, the solder and the substrate are given, a laser soldering system equipped with two galvanometer scanners and an f-theta lens has obvious advantages in soldering speed as compared with the traditional laser soldering system with moving worktable or laser head, because the reflection of the laser beam through the scanning galvanometers overcomes the restriction of the mechanical inertia of the laser head and worktable. In addition, the path that laser beam has scanned in the process of soldering is optimized. The optimization can greatly shorten the total scanning distance and improve the soldering speed without any additional hardware cost"

SMTAI Offers Four Important Symposia

EMS007: "The second phase of the NASA-DoD Lead-Free Consortium project is providing unprecedented data on the long-term performance of lead-free interconnections at this year's world renowned Lead-Free Soldering Technology Symposium. The scope of these experiments addresses alternative surface finishes, as well as the performance of mixed SnPb/Pb-free solder joints and the effects of rework activities.

Other sessions will include the Impact of Lead-Free Materials and Soldering Processes and Lead-Free Solder Joint Reliability."

Solder dross recycling system finds success

Dataweek: "The world price of solder is at an all time high, so reducing solder consumption – and therefore costs – should be on every electronics manufacturer’s wish list.

On average, it is estimated that companies throw away 75% of their solder as dross, but by automating solder dross recovery from the wave soldering process, a company can actually reduce de-drossing time by up to 80% and solder purchases by up to 50%. This article looks at how one company worked with its equipment supplier to automate this process in-house."

Integration of the NIST and SURDAT databases on physical properties of lead-free solder alloys

Scopus: "The electronic SURDAT database published in 2007 (available freely from the website www.imim.pl/english) is being integrated with the NIST database (available freely from www.boulder.nist.gov/div853/lead-free/solders.html) to provide a single source for data on lead-free (Pb-free) soldering alloys. The NIST database was developed to support circuit board designers, and so it is focused primarily on mechanical properties. In contrast, the SURDAT database is focused primarily on thermophysical properties. Together, they will form a much more complete source for the properties of Pb-free solder alloys."

Effect of Ag content on solidification cracking susceptibility of Sn-Ag-Cu solder joints

Scopus: "In the present work, the effect of Ag content on solidification cracking susceptibility of Sn-Ag-Cu solder joints has been investigated. Solders containing 1.0 wt.% to 3.8 wt.% Ag were used in the experiment. Solidification cracks were created using a copper self-restraint specimen, which could simulate the process of solidification cracking. Meanwhile, solidification cracking susceptibility was evaluated by comparing the total crack length of the solder joint.

The results indicate that solidification cracks exist in solder joints with 1.0 wt.% to 3.0 wt.% Ag content, whereas there are no cracks in Sn-3.8Ag-0.7Cu solder joints. When the Ag content increases from 1.0 wt.% to 3.0 wt.%, the total crack length of Sn-Ag-Cu solder joints increases to a maximum and then drops to zero when the Ag content reaches 3.8 wt.%. In addition, the susceptibility to solidification cracking is observed as follows: SAC207 > SAC305 > SAC107 > SAC387"

Lu, W., Shi, Y., Lei, Y.

College of Materials Science and Engineering, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, 100124 Beijing, China

SMTA Conference Shenzhen China, September 2010

SMTA - The Surface Mount Technology Association: "The SMTA China will organize the SMTA China South Conference 2010 in late-August in Shenzhen. This event, held in conjunction with NEPCON South China 2010, will address the industry's most pressing issues in electronics manufacturing, advanced packaging and lead-free reliability."

China to widen RoHS rules to all electrical & electronic products?

Chemical Watch: "The Chinese Ministry of Industry and Information Technology issued 'draft measures for the pollution control of electrical and electronic products' for consultation on 16 July, according to Brussels-based regulatory analysis and technical lobbying firm Young & Global Partners (YGP). The company says a key proposal is to broaden the definition of products covered by the measures to encompass all electrical and electronic products which operate."