Hi, Werner, No, I haven't seen any real evidence either. As I said in my reply post to Patti, I haven't actually tried FRS's myself, and I should add that I don't know anyone else who has. Your argument is logical, though - FRS appears better in accelerated testing, but long term reliability in the real world is not known yet. NIST (National Institute of STandards & Technology), with MSEL (Material Science and Engineering Lab) seem to have been doing quite a bit of research into FRS's, but mostly it all seems to be "new", without much history. Time, do doubt, will tell! Apart from being a bit more expensive to buy, I don't see much harm can be done in using these solders, though I don't know what the chemistries involved are for the additional dopants used. Do you have any interesting info to share on the subject? Peter Duncan [log in to unmask] 26/06/2002 07:36 PM To: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group@ST Domain, [log in to unmask] cc: Subject: Re: [TN] fractured solder joints Hi Peter, I have heard about "Fatigue Resistant Solders" but I have never seen any evidence that those in fact are fatigue resistant in actual use environment. Inaccelerated testing fine-grained solder last about double the fatigue cycles than coarse grained solder, but that does not translate to a real reliability increase in non-accelerated environments. Have you seen any real evisence? Werner Engelmaier [This e-mail is confidential and may also be privileged. If you are not the intended recipient, please delete it and notify us immediately; you should not copy or use it for any purpose, nor disclose its contents to any other person. Thank you.] --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------