High-Temperature Thermal Conductivity and Thermal Cycling Behavior of Cu–B/Diamond Composites

Diamond particle-reinforced copper matrix (Cu/diamond) composites are currently considered as a promising thermal management material due to their high thermal conductivity and matching coefficient of thermal expansion (CTE) with the semiconductor. In this article, the Cu–
$x\text{B}$
/diamond (
$x = 0.1$
–1.0 wt%) composites with 67% diamond volume fraction were produced by gas-pressure infiltration. The thermal conductivity of the Cu–B/diamond composites decreases with the increasing temperature from 323 to 673 K, owing to the property change of the composite components. The samples were subjected to 100 thermal cycles from 218 to 423 K to investigate the long-term stability of the Cu–B/diamond composites. The results suggest that the interface structure evolution plays a critical role in determining the high-temperature thermal conductivity and thermal cycling behavior of the Cu–B/diamond composites. By measuring the thermal properties before and after thermal cycling, we found that the Cu–0.5wt%B/diamond composite has the best thermal stability. After 100 thermal cycles, the room temperature thermal conductivity remains almost unchanged at ~740 W/mK, and the CTE increases slightly from 4.88 to 4.97 ppm/K. This article expands the understanding of the thermal properties of the Cu-B/diamond composites and provides a fundamental basis for their electronics packaging applications.