Investigation On Preparation And Properties Of Iamond-Metal Composites

With the improvement of electronic components’ power and circuit integration,diamond/metal composite was considered to be one of electronic packaging material’sdevelopment trends as its high thermal conductivity, adjustable coefficient of thermalexpansion and low density, and so on. Thus the research of diamond/Cu composite hasimportant significance and broad prospect in the field of electronic packaging.Diamond/Cu composites were prepared by ultrahigh pressure powder method (UHPS-PM), ultrahigh pressure infiltration method (UHPS-PM) and spark plasma sintering (SPS)technology. The influences of sintering temperature (1000~1400℃), sintering pressure(3~5.3GPa) and holding time (5~10min) on the thermal conductivity and relative densityof composites were studied. The results show that with the increasing of sinteringtemperature, both the relative density and thermal conductivity increase. The relativedensity(＞97%) of composite prepared by UHPS is much higher than SPS. The thermalconductivity of composite reaches only250W/(m·K) prepared by UHPS-PM and646W/(m·K) by UHPS-IM. The relative density and thermal conductivity have improvedto some extent through extending the holding time. The diamond is not graphitized duringthe ultrahigh pressure sintering.The effect of diamond volume fraction on thermal conductivity was tested andanalyzed according to Geometric average model and Maxwell model. The results showthat thermal conductivity increases with the diamond volume fraction increasing below75%, which is opposite to the theoretical calculation model. And then decreases when thevolume fraction above75%. The thermal conductivity of composite reaches the highestwhen the diamond volume fraction is90%, and now it is187W/(m·K). The relative densityincreases with the increasing of diamond particle size when using UHPS-IM to prepare thecomposites. The cracks of diamond/Cu composite decrease and the diamond directlycontacts with each other. Both thermal conductivity and thermal expansion coefficient ofcomposites increase with the increasing of diamond particle size. The thermal conductivityof Ti coated diamond/Cu composite reaches670W/(m·K) when the diamond particle sizeis200μm.