Characteristics of the Sn-Pb Eutectic Solder Bump Formed via Fluxless Laser Reflow Soldering

摘要

In an attempt to develop a fluxless reflow solderbumping process, the effects of processing variables, whichinclude energy input rate and time, and the shape of solder diskon the microstructure of the solder/Cu pad interface and theshear strength of the joints were investigated. It wasdemonstrated that a proper combination of the variables couldlead to the formation of a spherical solder bump with shearstrength comparable to that formed via the conventional reflowsoldering process. In addition, the kinetics of Cu pad dissolutioninto the solder during laser heating was modeled numerically toelucidate intermetallic formation mechanism at the solder/Cu pad interface.