MOISTURE MIGRATION AND CRACKING IN PLASTIC QUAD FLAT PACKAGES (PQFPS)

Moisture migration in PQFPs (plastic quad flat packages) was investiga ted analytically and experimentally. Coupons made of the molding compo und material were exposed to humid air for an extended time to determi ne its equilibrium moisture composition as a function of environmental moisture level. An IR (infrared) heating test was designed to simulat e the high-temperature heat reflow process when PQFPs are soldered on computer boards. The C-SAM (C-mode Scanning Acoustic Microscopy) techn ique was employed to measure the delaminated areas. All packages faile d after IR heating when the moisture content in PQFPs was higher than 60 percent of the equilibrium composition.