Rigid-Flex boards need to be dry during any thermal excursions, and the temperatures need to be limited to the lowest practical levels. The flex materials readily absorb and hold moisture. The inability of the moisture to quickly escape from these boards creates forces at solder temperatures that can tear apart the structure. Prebaking is critical, and controlling hand/rework operations is always a challenge. Andy Magee - Applications Engineer Rogers - Circuit Materials Unit Tel: (602) 917-5237 Fax: (602) 917-5256 E-Mail: [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Rigid/Flex: Open Circuits Author: GeoFranc (GeoFranck) {NAME:GeoFranck|EMS:INTERNET|MBX:[log in to unmask] at MCIMAIL Date: 9/14/95 9:10 PM Problem: We experience an unacceptable failure rate with open in rigid flex boards AFTER assemby and thermal cycling. Question: I feel there is a good chance the problem is in the assembly process. What kind of things should I look for? The boards are mixed surface mount and thru-hole, with much hand soldering and rework. Thanks George Franck