Microstructure and properties of electronic packaging shell with high silicon carbide aluminum-base composites by semi-solid thixoforming

Abstract

The electronic packaging shell with high silicon carbide aluminum-base composites was prepared by semi-solid thixoforming technique. The flow characteristic of the SiC particulate was analyzed. The microstructures of different parts of the shell were observed by scanning electron microscopy and optical microscopy, and the thermophysical and mechanical properties of the shell were tested. The results show that there exists the segregation phenomenon between the SiC particulate and the liquid phase during thixoforming, the liquid phase flows from the shell, and the SiC particles accumulate at the bottom of the shell. The volume fraction of SiC decreases gradually from the bottom to the walls. Accordingly, the thermal conductivities of bottom center and walls are 178 and 164 W·m⁻¹·K⁻¹, the coefficients of thermal expansion (CTE) are 8.2×10⁻⁶ and 12.6×10⁻⁶ K⁻¹, respectively. The flexural strength decreases slightly from 437 to 347 MPa. The microstructures and properties of the shell show gradient distribution.