Dave, Assuming that you have other hand soldered 0402s on the PBA, the tidbit that the resistors are in the same location causes my money to land on depanelization. Chris -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Tuesday, October 27, 2009 9:16 AM To: [log in to unmask] Subject: Re: [TN] Question regarding 0402 resistors and ceramic capacitors Hi Dave - as always, the TechNet crew is providing some great information. I just wanted to add support to Rich Stadem's detailed comments - incorrect manual soldering practices. The optimum solder process for ceramic resistors and capacitors would be reflow/hot air methods. However, thousands of chip Rs&Cs are manually soldered every day in the electronics industry very reliably. There is one major issue - if the soldering iron comes in contact with the resistor or capacitor termination then there is a high potential for having induced a crack that will not be immediately apparent. I recommend you review the operator manual soldering procedure and emphasize the importance of not touching the component termination during soldering. AVX has a technical paper authored by John Maxwell titled "Cracks" The Hidden Defect" which is very good on describing cracking root causes. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] Dave Connitt <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 10/26/2009 05:05 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to [log in to unmask] To [log in to unmask] cc 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------