An investigation of the bonding properties of Cu particle-filled solderable isotropic polymer composites (Cu-SIPCs)

This study developed Cu particle-filled solderable isotropic polymer composites (Cu-SIPCs) to improve the bonding properties of SIPCs with low-melting-point solder (LMPS) fillers. To examine the influence of Cu particle concentration on the bonding properties of Cu-SIPC joints, Cu-SIPCs comprising different Cu particle concentrations in the conductive fillers were formulated, and a bonding test using a quad flat package was conducted. The bonding properties of these joints were measured and compared. The Cu-SIPCs with a Cu particle content of below 10 vol% formed a wide and reliable metallurgical conduction path, with uniformly dispersed Cu particles, due to the proper internal flow and wetting behavior exhibited by molten LMPS fillers. The mechanical bonding strength of the Cu-SIPC joints increased linearly with an increase in the Cu particle content due to the mechanical enhancement effect offered by the Cu particles within the conduction path. However, Cu-SIPCs with excessively high Cu particle concentrations formed weakly shaped conduction paths because of the partly raised viscosity of molten LMPSs and the local agglomeration of Cu particles, which diminished the fluidity of molten LMPSs.