That is what I initially thought, but didn't Franklin mean Cu filled via??? Vladimir ----- Original Message ----- From: TechNet <[log in to unmask]> To: [log in to unmask] <[log in to unmask]> Sent: Tue Mar 18 22:44:41 2008 Subject: Re: [TN] How much stress is needed? Hi Franklin, You describe a classic via barrel crack—comes from the thermal expansion mismatch between the ED copper and the PCB resin in the z-direction during the soldering processes [the hotter the worse—read lead-free] [you should be taking my workshop on the subject at IPC EXPO/APEX on the morniong of March 31. Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com ************** Create a Home Theater Like the Pros. Watch the video on AOL Home. (http://home.aol.com/diy/home-improvement-eric-stromer?video=15?ncid=aolhom00030000000001) --------------------------------------------------- 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 -----------------------------------------------------