The structure and thermal conductivity of the diffusion-bonded interface of diamond-copper composite material prepared by spark-plasma sintering based on a molybdenum interlayer

An efficient thermal conduction characteristic is significant for electronic packaging materials. The diamond‑copper (Cu) composite material is considered to offer the most potential as a thermal management material, however, the coefficient of thermal conductivity (CTC) of the material is decreased due to the presence of bonded interface defects and the poor wettability, limiting the application of the material. Spark plasma sintering (SPS) diffusion bonding was used to join the diamond-Cu composite material. After adding a molybdenum (Mo) interlayer to the bonded interface, a reliable bonded interface was formed. The CTC of the material increases from 658.1 W/(m·K) to 724.33 W/(m·K), and the coefficient of thermal expansion (CTE) is 6.1 × 10⁻⁶ K⁻¹, which matches well with the semiconductor chip. The reduction of interfacial defects, the enhancement of bonding ability, the elevation of material densities enhance the thermal conductivity of the material, the generation of Mo₂C at the interface enhances the coupling of phonons at the interface, the hybridization of electron orbitals, and thus the enhancement of interfacial thermal conductivity. The research provides theoretical support for modification of the interface of the diamond-Cu composite material.