In the last 3 weeks I have given "Lead-Free" (Really WEEE/RoHS Compliant Assembly) workshops at Toronto, Salt Lake City, Manchester, NH, and Montreal. In addition, I have monitored the IPC's Leadfree Electronics Assembly Forum for some time.
What trends do I see? Here they are:
1. Shockingly, a significant minority of companies are still saying, "What is WEEE/RoHS?"
2. On the brighter side, the majority that are "getting with the program" now recognize it is not just "lead-free" assembly, but RoHS compliant assembly that is the issue.
3. There has now been developed a significant reliability data base that suggests that, in most applications, lead-free assembly has equal or better reliability than tin-lead assembly. Motorola has approaching 100 million lead-free cellular phones in the field since September 2001 with equal or better reliability performance.
However, I am sympathetic to the worry for very long term (> 10 years) reliability concerns for lead-free assembly. My concerns rest on the extreme soluability of copper in lead-free solder and the creation of Kirkendall voids at the copper/solder interface over time even at room temperature due to this soluability.
4. Few seem to recognize the overwhelming advantage that lead-free assembly has in allowing closer pad spacings on PWBs. This beneft is due to lead-free solder's tendency to not wet as well as tin-lead solder. In 5 years, many companies will be saying that they could not manufacture their miniturized products if they were assembled with tin-lead solder. See the photo above. Motorola has a patent pending on this discovery.