Peter and all - Actually, the IPC/Jedec spec scratches the surface - MSD is more involved than most practitioners know about. I highly recommend some excellent papers, including one by Dr. Schook of ATT who seems to be the MSD whiz at the Cogiscan website. The Cogiscan people are MSD gurus. They are at www.cogiscan.com Phil Zarrow ITM Consulting Durham, NH USA www.ITM-SMT.com