New Electronic Packaging Diamond / Copper Composite Material

Diamond/copper composite material compared with traditional electronic packaging materials,which had low coefficient of thermal expansion and high thermal conductivity, besides, the coefficient of thermal expansion matches well of Si and GaAs. It was one of the products should be developed,because it lined with modern information technology requirements of the development,and electronic technology has potential applications.In this paper, the diamond/copper composite material were prepared by repressing and re-sintering technology and spark plasma sintering (SPS). The micrograph were observation and analysis by optical microscopy, XRD, SEM.The coefficient of thermal expansion and thermal conductivity of composite materials were measured by thermal analyzer and thermal diffusivity.The relative density and coefficient of thermal expansion were measured and analyzed in the repressing and re-sintering process,the results showed that the relative density of composites elevated with increasing compacting pressur. but over 2000MPa, the compacting pressure didn't have so much influence on the relative density.When sintering temperature was 890℃, the relative density of composites reached the maximum, but over 890℃, the relative density of composites began to decreasing with increasing sintering temperature due to the graphitization. Proper longer sintering time could contribute to improve the relative density.At last,the research obtained a preparation technology which diamond size was 40μm, pressing pressure was2000Mpa,Sintering temperature was890℃and sintering time was 8h. The volume content of 50% of the composite material relative density reached 90.15% and the coefficient of thermal expansion was 9.206×10-6/K(100℃). When the diamond had identical particles size, the composite relative density increased with the volume content of diamond decreases; when the diamond had identical volume content, the relative density of composites increased with increasing particle size.The coefficient of thermal expansion of diamond/copper composite material increased with temperature increased. when the diamond had identical volume content,the coefficient of thermal expansion increased with diamond particles size increases; when the diamond had identical particles size, coefficient of thermal expansion of composites increasing with volume content of diamond decreases. At the same time, the coefficient of thermal expansion of the diamond/Cu composites was theoretical calculated according to the ROM model, Turner model and Kerner model.In the spark plasma sintering process:the thermal conductivity and relative density were measured and analyzed:the thermal conductivity elevated with the increasing of the relative density of composites,diamond particle size; the thermal conductivity decreased with the increasing of the volume fraction of diamond which were opposite to the theoretical calculation by using Maxwell model and P.G. Klemens model.By optimizing the preparation process made the diamond/copper composite material relative density was:94.04%, and the thermal conductivity ratewas:190.54 W/(m·K).