Prefabrication and Characterization of Copper–Silver Foam Composites for Low-Temperature Interconnection of Power Modules

A copper foam–silver composite for large-area interconnections of power modules is proposed, which is prepared by homogeneously mixing a solid copper foam skeleton with a micro-silver paste. The shear strength of the composite was increased to 52.46 MPa by optimizing the preparation and sintering processes. The influence of the primary parameters of the copper foam material on the quality of the sintered joints was discussed, and the morphology and distribution of the sintered silver in the sintered layer of the composite were elucidated and the fracture mode was described. With the increase in copper foam thickness, the deformation rate of the joints increased from 3.13% to 20.23%, the porosity of sintered silver in the composite sintered joints decreased from 23.05% to 2.42%, and the shear strength increased from 34.8 MPa to 59.7 MPa, compared with the sintered silver joints under the same process, the shear strength increased by 4.61% (50.04 MPa for sintered silver joints). The thermal conductivity of the fabricated copper foam–silver composites was tested using a laser thermal conductivity meter. The thermal resistance of a double-sided cooling power module using the copper foam–silver composite as the interconnection layers were evaluated.