The Navy did a surface mount repair study in June 1987. The conclusion of this study is that the "long term reliability of a solder joint will be jeopardized with multiple rework cycles. With copper dissolving away during thermal processing, the pads will inherently lose their structural compliancy. The copper goes into solution forming brittle compounds such as Cu6Sn6. These brittle intermetallic layers may cause long-term solder joint fatiguing problems." They state that on 2 oz copper 100% of the pad would dissolve in 12 cycles. My question does anybody know of any recent studies that would support or counter this study. Do other companies limit the number of heat cycle on a pad? *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************