THE FINITE ELEMENT MODEL OF MULTI-SCALE STRUCTURES IN TSV INTERPOSER PACKAGES

In 3D through-silicon-via (TSV) interposer packages, there are many micro bumps and micro solder balls, the size of which might be different by 1000 times. This multi-scale structure brings difficulties in building the finite element model. Homogenization method was adopted to avoid these difficulties in this paper. The micro bump/underfill layer between the chip and the TSV interposer, and the micro solder ball/underfill layer between the interposer and the substrate were replaced by homogenous material layers. Four different homogenization schemes were proposed to compute the thermal fatigue life of the board level solder joints, and the results were compared. It is suggested that the micro bump/underfill layer between the chip and the interposers, and the micro solder ball/underfill layer between the interposer and the substrate can be replaced by their own underfill material layer in a finite element analysis of the thermal fatigue life of board level solder joints.