Hi Dave, The most likely time for the cracking is during cooling from soldering. I bet these RCs have larger solder fillet than non-cracked chip components. You combine large CTE-mismatch [ceramic vs. FR-4], more rapid cooling after manual soldering, large solder fillets acting like vice grips—and you have a potent brew for trouble. Of course, if all of this is Pb-free—the worse. Werner -----Original Message----- From: Dave Connitt <[log in to unmask]> To: [log in to unmask] Sent: Mon, Oct 26, 2009 6:05 pm Subject: [TN] Question regarding 0402 resistors and ceramic capacitors Hi Everybody, I think I know the answer to this but here goes.. We recently started using 0402 resistors and ceramic capacitors on a development project. Yes, it is our first time going this small... Everything was progressing OK until this morning when it I found out a couple of resistors cracked during temperature cycle testing (-70F to +150F). I also found out that these parts were soldered by hand. Both cracked parts are located in the same area, in fact I think they are the same parts in both instances. We can't really determine when the parts were cracked but it sounds like they may have been cracked at assembly as they were found during trouble shooting of the circuit. My question is could this failure be a result of trying to hand solder these parts? I am wondering if they were pushed beyond their maximum temp and time duration during soldering? We should have ran these through our SMT line but time didn't allow for it. You how it goes, there is never time to do it right the first time but there is always time to do it over.... If someone has another possible scenario I could investigate, I would appreciate any help. Thanks, Dave Connitt CID+ Printed Circuit Designer A Wholly Owned Subsidiary of: L3 Communications 3975 McMann Road Cincinnati, Ohio 45245 Ph. 513- 943-2010 Fax 513-943-2288 --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------