Abstract: SiC particle reinforced Cu matrix composites were fabricated via hot isostatic processing for electronic packaging. The results indicate that the coefficient of the thermal expansion (CTE) of composites depends on the SiC particle size and its volume fraction. The minimal CTE value has been obtained from an annealing for releasing residual stress. The thermal conductivity is found to be higher when the volume fraction of Cu exceeds a threshold because of the matrix formed a continuous phase.