Rich, first, make sure you have an initial overlap of let's say 25 mils on each pad. Secondo, you may want to check if it happens with other manufacturers than Kemet & AVX. Is the push-pull effect occured in the oven due to the plating of the parts? You mentioned that the parts were well centered. Also, validate the direction of your misalignment and check if it is always the same. It may be helpful to find the root cause. Having to choose between a good solder joint on a misaligned part and a bad solder joint on a centered component I would choose the first. As you can see on Fig. 12-31, the solder paste didn't wet at all. But this is not your case. You may want to perform a shear test to raise your confidence level that your shippable products are within specifications. Good luck in your finding, Eric -----Original Message----- From: Rich Lasko [mailto:[log in to unmask]] Sent: Monday, February 16, 2004 9:14 AM To: [log in to unmask] Subject: [TN] SMT Chip Components End Overlap (Section 12.2.2.8) Greetings everyone, Let me first start off with a little background information. I am currently investigating a random issue on one of our SMT assemblies. The issue revolves around four (4) 0805 chip components. (Kemet C0805C824K8RAC & AVX VC080505A150DP) During initial placement of the components (pre reflow) the part is centered directly between the lands and there is good component to pad overlap. However, during post reflow we are noticing that occasionally (on only these four components) the parts shift so that the component to pad overlap is now being questioned. Please note, the end overlap looks pretty close to Figure 12-31 however on my products there is a good solder joint that meets both the minimum fillet height and end joint width criteria. So my question is, if the component is soldered but is borderline and questionable as to the amount of end overlap should this be reworked? I have always felt that if you have a good solder joint to begin with that touching it to move this component less than 0.015" is running the risk of doing more damage than good. Thoughts? Thanks in advance for your feedback. Regards, Rich Lasko BEI, LLC --------------------------------------------------- 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------