Pb-Free Alloy Alternatives
Project Statement & SOWStatement of Work (December 14, 2007; Version 2.0)
Project Statement (December 14, 2007; Version 2.0)
Project ObjectiveThis group’s objective is to provide guidance that will help the electronics industry better manage Pb-free alloy proliferation.
BackgroundMany BGA suppliers are changing the alloys used for Pb-free solder balls to improve mechanical shock performance. As a result, the variety of Pb-free alloys for solder ball terminations is increasing. Several of these alloys have lower levels of silver (Ag) and, therefore, a higher melting point (up to 10(C higher), which may require a change in printed circuit assembly (PCA) manufacturing processes. Suppliers are also promoting a variety of wave solder alloys to address concerns about copper dissolution, barrel fill, common wave defects, and the high cost of alloys. However, the impact of these alloys on the entire PCA system of materials and on long-term reliability is not well understood. As with the solder ball alloys, there are concerns about higher melting temperature, as well as mixing of wave solder with SMT and rework alloys, solder joint reliability, change in alloy composition with time in the pot, and a lack of methodology and test requirements for alloy assessment.
Scope of WorkPhase I will focus on understanding what knowledge is available for the various alloys being deployed and the related gaps in data. The group will work with the supply base to help manage the variability as well as to encourage the closure of knowledge gaps.
- Propose updates to JEDEC standard JESD46 (Customer Notification of Product/Process Changes by Semiconductor Suppliers) to address concerns with changing BGA/CSP part numbers when the ball alloy is changed. Submit this proposal to the JC-14 Committee (Quality and Reliability of Solid State Products).
- Identify concerns related to J-STD-006 and alternate alloys communicated to the J-STD-006 committee.
- Develop a “strawman” table of data requirements for assessment of Pb-free solder alloys.
- Develop a draft method to establish “e” categories for alternative alloys, and submit to IPC and JEDEC for inclusion in J-STD-609 (Marking and Labeling of Components, PCBs and PCBAs to Identify Lead (Pb), Pb-Free and Other Attributes).
- Develop a list of technical and non-technical issues with the use of various chemical elements in Pb-free solder alloys.
Presentations & Reports
- iNEMI Recommendations for Managing Pb-Free Alloy Alternatives
- “Guidelines for Lead-free Solder Alloys for Wave Solder and Pin-Through-Hole Rework (Rev. 1.0, March 2008)”, EMS Forum on Lead-Free PCB Assembly
- Manufacturability and Reliability Impacts of Alternate Pb-Free BGA Ball Alloys; Greg Henshall, Michael Roesch, Kris Troxel, Helen Holder, Jian Miremadi, HP Global Engineering Services (June 2007)