Research On Interface Moderation And Thermal Conductivity Of Diamond/Copper Composites

In today’s booming microelectronics industry,the power density of electronic devices has increased significantly,and efficient heat dissipation has become one of the important conditions for the promotion and application of new generation of high performance and high power electronic devices.The diamond/copper composite material,which is made of diamond with ultra-high thermal conductivity and low thermal expansion coefficient and copper with high thermal conductivity metal,is expected to be a new generation of efficient heat dissipation material.However,the problems of poor wettability and poor interfacial bonding between diamond and copper can cause the thermal conductivity of their composites to be much lower than the theoretical value.Therefore,it is of great importance and technical value to realize the interfacial regulation and optimization of diamond/copper composites and to prepare diamond/copper composites with excellent performance.In this paper,we systematically analyzed many factors affecting the interfacial thermal conductivity of the composite between diamond and copper based on the differential effective medium（DEM）model and the phonon mismatch model（AMM）,and then experimentally chose the salt bath method and the thermal diffusion method to tungsten plating on the surface of diamond particles,and then chemically coated copper on the diamond surface after tungsten plating,and prepared the diamond/copper composite with excellent performance by vacuum hot press sintering.composite materials by vacuum hot-pressure sintering.The experimental study analyzed the effect of different preparation process parameters on the properties of diamond/copper composites,and the experimental results showed that:After tungsten plating by diamond salt bath,the surface roughness of the plated layer is obviously increased,and there are more surface holes,large grains are generated on the surface,the plated layer has less bonding force,easy to peel off,and the degree of densification is not high;while after tungsten plating by hot diffusion method,the surface of the plated layer is obviously more uniform and dense,and the roughness is smaller,with lower impurity content and higher carbide generation.Therefore,the diffusion tungsten plating layer is more stable and the surface layer is not easy to peel off,which can provide more performance support for the interfacial bonding of composite materials,and the best process parameters for tungsten plating treatment are experimentally derived as follows:Under the condition that the mass ratio of Diamond:W:WO₃ is 1:1:0.5,the plating temperature is 1050℃and the holding time is 60 min,at this time,the thickness of the plated layer is about 455 nm,and this layer is uniform and dense without cracks and crater defects.Subsequently,a uniform and dense Cu layer with a thickness of about 1.61μm was deposited on the diamond surface after tungsten plating by chemical plating at an optimum plating solution temperature of 45℃,resulting in W-Cu bilayer plated diamond particles.During the subsequent high-temperature sintering process,the pure copper powder was in full contact with the surface double-coated diamond particles,and the presence of the W-Cu layer could promote the effective interfacial bonding between the diamond particles and the copper substrate.It was found that the densities and thermal conductivities of the diamond/copper composites increased and then decreased with increasing diamond volume fraction,and reached the maximum at 55 vol.%diamond volume fraction.Then,the optimum sintering process parameters were obtained by regulating the hot pressing sintering process parameters to optimize the interfacial structure and improve the thermal conductivity of the composite:The sintering temperature was 1050℃and the holding time was 3 h.After the surface modification of diamond particles,it was found that the interfacial bonding and thermal conductivity of the composite material made of diamond and pure copper powder after the treatment of the optimal plating process parameters was also the best,and W-Cu double-layer plating significantly improved the interfacial bonding state between diamond particles and pure copper powder and promoted the improvement of the thermal conductivity of its composite material,and the W-Cu double-layer plating had better performance than the Diamond/Cu composite with W single-layer plating,with a dense density of 99.24%and a thermal conductivity of 536.23 W/（m·K）.