I agree that Pb free implementation hasn't been a disaster (with the exception of tin whiskers), but a few years without a bunch of major reliability catastrophes isn't a great indication of equivalent reliability.  Besides the lack of time that's passed, especially for electronics requiring a long service life, there's also the fact that we've designed around some of the weaknesses of SAC alloys.  For example, adding corner bond or underfill to pass BGA drop tests or using multiple smaller ceramic resistors in the place of one larger resistor to pass thermal cycling.  If we'd left our designs alone and only changed the solder alloy we'd be seeing more reliability problems.  In many situations Pb free is not as reliable as SnPb if everything but the alloy is kept equal.

Scott Post
Staff Manufacturing Engineer
P.O.U. 0000-001E-0CTC
2151 E. Lincoln Road
Kokomo, Indiana    46904-9005
765-451-2983 (Phone)
765-451-0287 (FAX)

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric Christison
Sent: Thursday, July 14, 2011 12:20 PM
To: [log in to unmask]
Subject: [TN] Lead Free solder has performed well...

http://www.designnews.com/author.asp?section_id=1389&doc_id=231199&f_src=designnews_gnews

"Dr. Ronald Lasky, Dartmouth professor of engineering and a frequent blogger on solder, claims the transition to lead-free was a grand success. “A lot of people claim that lead-free solder is not as reliable as lead-based solder,” Lasky told me. “We’re now five years into the implementation of RoHS, and we’ve made $3 trillion work of electronic.
We haven’t really noticed any big change in reliability.”"

I thought some of you may be interested in the above article.

Regards,


--
Eric Christison
Consumer&  Micro group
Imaging Division

STMicroelectronics (R&D) Ltd
33 Pinkhill
Edinburgh EH12 7BF
United Kingdom

Tel:    +44 (0)131 336 6165
Fax:    + 44 (0)131 336 6001

The contents of the email are ST confidential.




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