언더필이 적용된 μBGA 솔더 접합부의 열피로특성

Abstract

There have been many researches for small scale packages such as CSP, BGA, and Flipchip. Underfill encapsulant technology is one of the latest assembly technologies. The underfill encapsulant could enhance the reliability of the packages by flowing into the gap between die and substrate. In this paper, the effects of underfill packages by both aspects of thermal and mechanical reliabilities are studied. Especially, it is focused to value board-level reliability whether by the underfill is applied or not. First of all, The predicted thermal fatigue lifes of underfilled and no underfilled μBGA solder joints are performed by Coffin-Manson's equation and FEA program, ANSYS(version 5.62). Also, the thermal fatigue lifes of μBGA solder joints are experimented by thermal cycle test during the temperature, 218K to 423K. Consequently, both experimental and numerical study show that μBGA with underfill has over ten times better fatigue life than μBGA without underfill.