The latest edition of The Embedded Muse newsletter from The Ganssle Group has a good summary with a few links about this topic.
The EU’s RoHS standards have caused a wholesale retreat from the use of lead in solder. While their intentions are noble, the electronics industry is likely to suffer mightily since alternative solders spontaneously grow tin whiskers that can, and have, create short circuits.
This problem is actually a bit of a blessing for manufacturers with short warranties (< 2 years). It can force more rapid replacement/upgrade cycles yielding more sales dollars.
Back in the early 1990’s there was bill before the US Congress to force removal of lead from electronic solder in the US. The goal of the bill was to reduce lead exposure for children. The EIA and other organizations pointed out to the Congress that lead in children had long ago been traced to other sources, not electronics. The Congress rightly dropped the idea when they realized that lead from electronic circuits was only likely to get into children whose parents allow them to suck on electronic circuit boards. Now the EU has these RoHS regulations and if US manufactures want to sell to EU countries they are supposed to move to lead free solder.
I encourage every embedded systems engineer to head over and sign up for a free subscription to The Embedded Muse newsletter, a great source of embedded systems news and information delivered free to your inbox.
Lead free solder and tin whisker links:
NASA Goddard Tin Whisker Homepage
Roll back the lead-free initiative: 12 ROHS myths
Pushback
Pb-Free.com
THAT Corporation Links to Lead Free Information
Paul Hutchinson's Blog 