Material Selection and Parameter Optimization for Reliable TMV Pop Assembly

摘要

The successful integration of package-on-package (PoP) stacking utilizing through mold via (TMV) technology hinges on a robust assembly process. In this study, seven dip materials were investigated for high quality TMV PoP assembly by optimizing machine settings to achieve proper material transfer. Film thickness was varied for each material to transfer enough material (target of 50% ball coverage) while preventing parts from sticking within the film. Assemblies were reflowed in both air and N_2 atmospheres and yields were quantified. It was determined that flux dipping provides for better TMV assemblies in air reflow due to the flux's ability to wet to and subsequently protect the TMV solder ball during reflow. All paste dipped materials experienced significant fallout in air reflow due to a non-coalescing of the TMV solder joint. All materials provided 100% assembly yields in N2 reflow.