FE Modeling and Analysis on Thermosonic Flip Chip Bonding Process for Cu/low-k Wafer

Abstract

Thermosonic flip-chip bonding (TFCB) is an advanced integrated circuit package technology for area-array connections. The dynamic finite element (FE) analysis model was established for the TFCB process to explore dynamic stress and strain for the microstructure of the Cu/low-K wafer. Based on this model, the stress and strain evolution process was obtained for the wafer microstructure. From the analysis result, we found that the maximum von Mises stress distributions are mostly concentrated on the copper via areas, and the von Mises stress of the metal layer is always greater than that of the low-k layer. Based on the FE model analysis, the effect study of the process parameters were thus carried out, which included the effects by the ultrasonic vibration amplitude and the number of copper via. According to the results of modeling simulation, the parameter effects on stress and strain distribution were achieved. This study was useful for the parameter setting of the TFCB process and for optimizing the microstructure design of Cu/low-k Wafer.