Chris, What made you think compression?? Of solder mask has anything to do with the failure? Solder mask on SMD pads can act as a stress concentrator promoting crack formation, but I don't think it has anything to do with its compression or expansion. Regards, Vladimir SENTEC ------Original Message------ From: Chris Ball Sender: TechNet To: [log in to unmask] ReplyTo: TechNet E-Mail Forum ReplyTo: [log in to unmask] Sent: Sep 17, 2009 13:07 Subject: [TN] fractured SJs due to soldermask compression Hello, Starting a new branch here. "All of the other issues pale in the face of fractured SJs due to soldermask compression during cyclic operation." Is this concern specifically for BGAs, or the same for any soldermask defined pad, even including selectively waved through-hole (PbFree)? Thanks, -Chris This e-mail message is intended only for the use of the intended recipient(s). The information contained therein may be confidential or privileged, and its disclosure or reproduction is strictly prohibited. If you are not the intended recipient, please return it immediately to its sender at the above address and destroy it. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 ----------------------------------------------------- SENTEC 11 Canadian Road, Unit 7. Scarborough, ON M1R 5G1 Tel: (416) 899-1882 Fax: (905) 882-8812 www.sentec.ca