ECTC Panel Discussion

On May 31, an evening session Discussion was held entitled "Lead-Free Industry Update". With looming deadlines to remove 6 hazardous items from electronics in Europe and China, it was time to share progress. Robert Lanzone of Amkor Technology was the Chair.
Raj Masters of AMD first defined the details of the law that dictates Pb, Hg, Cd, and Cr6+ controls. For lead the exceptions are only those where no readily available option exist such as: high temperature attachment where Pb >85%, Pb in high end servers and communication equipment, Pb in many element alloys, Pb die attach in carriers that are flip. SnAg solders are being used to replace passive device lead attach and for BGA balls. In general, the greatest challenge is for the high reliability, long life time systems.
Sudipta Ray described the IBM Lead-Free Road Map. Although covered by exception today, IBM is developing a Lead-Free C4 bump and package. He discussed bumps of plated Sn/Ag or Sn/Cu as well as balls of 3-4% Ag and SAC alloys. In the case where long columns are needed, IBM is studying Cu colums with Sn/Ag solder coating.
Han Park discussed the Japanese market. The first step was to achieve lead-free solder paste over the 2000-2002 period. This demanded higher temperature reflow and much tighter profile control of the reflow oven temperatures. The second step has been lead-free terminals on the components. The last step will be full lead-free systems. Everything in the system must survive 260 C heating. There has been a change-over from wave soldering machines to high temperature processes.
Strongly suggested that more standardization should occur for the lead-free solders used throughout the world. Currently Japan supports Sn3Ag0.5Cu, NEMI Sn3.9Ag0.4-0.8Cu, and Europe Sn3.4-4.1Ag0.45-0.9Cu.
------Juergen Winterer of Infineon indicated that 70% of their products are shipped lead-free today. They use Sn plating that is usually 7 microns thick and matte finish. The also use SnAgCu for attaching BGAs. SnPb will only be used in niche technologies after 2006.
------Sherry Zhu of Kyocera described changing solder processes in a way where some backward compatibility would exist in components. Today a complete shift is lost when converting a line from SnPb to Lead-free. Tools used for Pb must be segregated from the lead-free. They use SnAgCu #305, 405, 382. They change the part number to avoid confusion in the next assembly performed by their customers. They are busy applying six sigma methodology on the new solder processes. A point was made that the SnZn9% material has a very short shelf life and easily oxidizes.
-------Robert Darveaux of Amkor indicated that the material properties on the different solders are often much different than those mentioned in the literature. Some of this is due to the difference of measuring pure materials in "dogbones" versus solders in action forming interfaces, but much was just the dependence of solder properties on preparation details that were often hidden from even the researcher. Bottom line: measure the properties you need under the conditions the materials actually encounter.
------Dongkai Shanggauan of Flextronics indicated they had switched from R&D to operational focus. In particular, they were working the "end of life" issues such as cost of electronics recover, reuse, and recycling. He indicated that they test the reliability of their PCB after 6 cycles of 260 C processing. In general they used the SAC solders where Ag is 3-4% and had narrowed their process windows considerably. He pointed out that most SAC solders were not bound by IP.