I was not involved in the product evaluation. And I can't answer your question. Perhaps Werner could give you an approach. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Simms, Michael Sent: Wednesday, January 12, 2005 10:36 AM To: [log in to unmask] Subject: [TN] FW: [TN] FW: FW: Flexible vs. rigid substrates Hello Guy, Thank you for your response. Our customer's concern is that the solder joints involved are on a rigid substrate and the substrate is flexed to some amount of curvature. The concern rests on the presumption that the solder joints are thus placed under some unknown but constant stress. Some of the engineers involved are concerned that no data may exist for the reliability of solder joints placed under constant stress. The solder joints may also be subjected to high temperature excursions during their service life. Some of the engineers reviewing the application have questioned putting solder joints under constant stress during their service life. The fear is that under constant stress, even without repeated flexing, reliability of the solder joints is compromised and their service life unpredictable and unknown. Wouldn't the use of flex material eliminate the stress? I was asked to review IPC documents to find what the industry position may be regarding flexing of rigid assemblies. So far, in my review of IPC documents and from some anecdotal responses from TechNet, it appears that the industry may not have addressed the acceptability of this type of application. Regards, Mike Mike Simms Chemist Trace Laboratories - Central 1150 W. Euclid Ave. Palatine, IL 60067 phone 847-934-5300 fax 847-934-4600 www.tracelabs.com --------------------------------------------------- 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 -----------------------------------------------------