Level 1 crackfree plastic packaging technology

Abstract

Cracking of plastic packages during printed circuit board (PCB) mounting is a serious customer concern as VLSI plastic packages house ever-increasing die sizes and are made thinner. Evolutionary improvements in package materials cannot prevent package cracking in the short term, especially in thin packages. A novel design, termed the "window flag", employs a central hole punched in the die pad to minimize the metal-polymer interface and maximize the silicon-mold compound interface in the die pad region. This window flag design results in crackfree performance following Level 1 preconditioning in QFPs, TQFPs, and SOJs. This solution stems from the key discovery that the silicon-mold compound interface is intrinsically very strong under preconditioning stresses.