For a starter, here is an answer on this China subject that I gave to a similar, slightly broader question on long term (chemical) stability of solders and fluxes in electronic assemblies recently. It's good for a perspective if nothing else. Hope it helps: -- Hmm, the answer to your question is a very long time, many decades for tin /lead solders. We know that from the life cycles of existing soldered assemblies, and other applications for tin and lead containing items. The alloys are stable and any degradation through temperature cycling results in a kind of work hardening which can lead to fractures under stress, but aside from lack of functionality nothing else happens. With no temperature extremes/cycling I would venture to say the life of a solder joint is probably centuries. The earliest soldered assemblies are still around OK, (Roman helmets that sort of stuff.) So far as leaching is concerned, or at least chemical attack from ingredients, the fluxes are defined as non corrosive by IPC for the applications they are in. A no clean flux is little different in this respect than its RMA predecessors and again we can point to decades of use. The worst conditions we can point to are probably those pertaining to landfill, end of life in other words. Here the studies show that leaded solders are stable, the US EPA did a study on environmental impact of leaded solders/electronics >15 years ago and you should be able to find that OK. If its OK in damp ground with acids etc from landfill its must be OK in ordinary air. Turning to lead free, the situation is not so clear, first there are a number of novel alloys involved so not so much history, secondly environmental impact studies on SAC alloys for example show they can leach into ground water from landfill, unlike leaded ones. Looking at the nearest thing to SACs, we get the tin/silvers, these have been used in the automotive and defence industries for about 50 years with no indications of unreliability, so for the purposes of this study we can say they are stable and we go back to the fluxes. They meet the same standards as leaded so no change. For documentation on this: as said the US EPA study, the British NPL has done some reliability studies and these are free to download. One of the biggest repositories of knowledge on line for solders is http://www.boulder.nist.gov/div853/lead%20free/props01.html and I would look there first for authoritative references. -- Regards Mike Fenner Indium Corporation -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of kwood716 Sent: Thursday, February 22, 2007 10:50 PM To: [log in to unmask] Subject: [TN] China / Solder Longevity Hi all, I have been asked to place a label on a product that is being sold in China that states how long, under normal circumstances, the solder joints, or solder I guess, will last. Anyone have experience with this issue? The material used is 63/37 no clean solder. _____ Saturn PCB Design, Inc. Kenneth J. Wood CID 2737 Bishop Lane Deltona, Fl 32725 Phone: 407-340-2668 email: <mailto:[log in to unmask]> [log in to unmask] www.saturnpcb.com <http://www.saturnpcb.com/> ***This email, its content and any files transmitted with it are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient please delete and contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. Messages sent via this medium may be subject to delays, non-delivery and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. In particular, Indium Corporation does not accept responsibility for changes made to this email after it was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.*** --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------