Simulation of Solder Crack Phenomenon in Molding Process

This letter presents for the new process of indirect transfer molding of solder with fluid effects based on epoxy molding compound (EMC) which is simple in structure and easy to flow smoothly between solder and chip bottom gap. The simulated results indicate that the worse principle stress over 200MPa per units, the different structure of material and rotation changes where reduce stress is helpful and added for design considerations. However, the impact of principle stress of backside Cu and package rotation shows better performance. For a restricted space of molding strip ratio arrangement, two important aspects influencing the node 1 to 8 and the principle gradient are studied: one is mold flow direction between vertical and parallel, the second is Cu pillar and backside Cu added which induce principle stress was obviously. Here we suggest and experimentally demonstrate a backside layer, package rotation for performing low stress impacts on solder, the stress index for corner deformation with pressure of principle stress severity in between.