Hot Isostatic Pressing of Dissimilar 6063Al-SiC/Al and 6063Al-Si/Al Joints for Electronic Packaging: A Comparative Study of Microstructure and Mechanical Properties

Functionally graded Al-based joints are promising for electronic packaging, yet achieving reliable dissimilar layer bonding remains challenging. Here, we compare 6063Al-SiC/Al and 6063Al-Si/Al joints fabricated by hot isostatic pressing (HIP). Although both achieve defect-free bonding, but the SiC/Al joint exhibits a far higher tensile strength of 253 MPa and an interfacial shear strength of 203 MPa than the Si/Al joint, which reaches only 155 MPa and 48 MPa, respectively. This disparity stems from distinct interface evolution: the SiC/Al joint features an atomically bonded interface with high strain shielding efficiency, confining thermal mismatch strain to a narrow region of approximately 15 µm adjacent to the interface and protecting the 6063Al substrate. In contrast, Si particle fragmentation, imperfect interfaces, and low strain shielding efficiency in the Si/Al joint promote stress concentration and widespread substrate deformation, leading to premature failure with a brittle cleavage mode. These results demonstrate that reinforcement structural stability and strain shielding efficiency of the composite are crucial for the reliability of graded Al joints in electronic packaging.