Fabrication of CuSiC metal matrix composites

Abstract

A CuSiC MMC heatspreader will offer high thermal conductivity between 250 and 325 W/mK and corresponding adjustable thermal expansion coefficient between 8.0 and 12.5 ppm/°C. The primary challenge of CuSiC manufacture was to prevent reaction between copper and silicon carbide during high temperature densification, which dramatically degraded the thermal conductivity. In this study, the key issue addressed was the Si attack of Cu at the temperatures necessary for CuSiC fabrication (850 to 1200°C). Decomposition of SiC in contact with copper will dissolve Si in Cu causing a dramatic decrease of Cu thermal conductivity. This diffusion of Si into Cu can be prevented by the application of reliable barrier layers to diminish mass transport through the diffusion path and thereby minimizing the chemical interaction. A reliable barrier coating was identified and used to fabricate the CuSiC composites. The CuSiC composites were then characterized by SEM, TEM, XRD and XPS. Chemical analysis and thermal conductivity by laser flash diffusivity measurement illustrated the effectiveness of the barriers. A CuSiC composite having thermal conductivity of 322.9 W/m-K was successfully fabricated.