무플럭스 레이저 리플로우 솔더링으로 형성된 Sn-Pb 공정 솔더 범프의 특성

Abstract

In an attempt to develop a fluxless reflow solder bumping process, the effects of processing variables, which include energy input rate and time, and the shape of solder disk on the microstructure of the solder/Cu pad interface and the shear strength of the joints were investigated. It was demonstrated that a proper combination of the variables could lead to the formation of a spherical solder bump with shear strength comparable to that formed via the conventional reflow soldering process. In addition, the kinetics of Cu pad dissolution into the solder during laser heating was modeled numerically to elucidate intermetallic formation mechanism at the solder/Cu pad interface.