In a message dated 99-01-13 19:42:26 EST, you write: << Typically, we tend to fail at the interface between the substrate (sometimes the PWB, sometimes the interposer) and the pad rather than in the solder joint. >> James, Guidelines for the dye penetrant procedure are available in a Motorola ".pdf" file on BGA reliability . Last reference I had for this document was: http://www.mot-sps.com/solutions/wired/pbga/pbga.html (or do a search for "BGA reliability" at: http://mot2.indirect.com/cgi- bin/search) Failures at the interface between the BGA substrate and pads may and do occur under your test conditions. They are an indication of not enough adhesion / robustness in the pad area (even after a couple of joints have failed elsewhere). One possible solution (if you are still in the design phase) is to redesign with a larger copper area under the solder mask. As mentionned by Per, you can also test at higher temperature which will help shift the failures from the pad/substrate to the solder joint. It all depends on what your goal is for that test and what your strength requirements are. Jean-Paul _____________________________________________________ Jean-Paul Clech EPSI Inc., P. O. Box 1522, Montclair, NJ 07042, USA tel: +1 (973)746-3796, fax: +1 (973)655-0815 SMT / BGA / CSP Reliability Specialists home page: http://members.aol.com/Epsiinc1/index.html ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################