Study On Properties Of Diamond/Cu Composites Prepared By Spark Plasma Sintering

With the development of electronic information technology,the integration of electronic components is getting higher,which makes the components produce a lot of heat in working process.How to dissipate heat efficiently has become a key issue.In addition,traditional thermal conductive materials can no longer meet the requirements of modern science and technology for electronic packaging materials.Diamond/Cu composites have become the research hotspot of thermal conductivity materials due to their advantages of high thermal conductivity,low thermal expansion and corrosion resistance.However,the performance of composite combined diamond and copper directly is poor because of non-wetting between diamond and copper.In recent years,it has been proved that introducing modified layer at the interface between diamond and copper or increasing the surface roughness of diamond are effective ways to improve the thermal conductivity of diamond/Cu composites.In order to increase the roughness of diamond surface and introduce the interface modification layer at the same time,four metal oxides,Cu O,Ti O₂,Cr₂O₃ and V₂O₅ were added to a copper matrix and combined with spark plasma sintering to prepare diamond/copper composites with high density and thermal conductivity.The results show that:（1）Thermodynamic analysis and TG-DSC data of raw materials proved that the four oxides can react with carbon formed by graphitization of diamond to form metal carbides at sintering temperature.The surface of diamond of composites prepared by adding four oxides became rough.X-ray diffraction analysis showed that Ti C,Cr₃C₂ and VC transition layers were formed at the interface of diamond/Cu composites with Ti O₂,Cr₂O₃ and V₂O₅addition.Furthermore,the thickness of the transition layer has been estimated to be about 100-300 nm by element line scanning,and its thickness is related to the added oxide content.（2）The sintering process of diamond/Cu composites with four oxides was optimized by controlling variable method,and the optimum content of oxides was determined.The results show that the sintering temperature is 850-900℃,the sintering pressure is 40-45 MPa,and the holding time is 15-20 min.The optimum content of Cu O,Ti O₂,Cr₂O₃ and V₂O₅ is 0.9wt.%,0.6 wt.%,1.0 wt.%and 1.2 wt.%respectively.（3）The maximum thermal conductivity of diamond/Cu composites with Cu O,Ti O₂,Cr₂O₃and V₂O₅ was 337 W/（m·K）,421 W/（m·K）,477 W/（m·K）and 502 W/（m·K）,respectively.The thermal conductivity of the diamond/Cu composites with Cu O is obviously lower,because there is no modified transition layer at the interface,and only improve the interfacial heat transfer efficiency by increasing the surface roughness of the diamond.（4）The theoretical thermal conductivity of diamond/Cu composites with Ti O₂,Cr₂O₃ and V₂O₅ was calculated by H-J model,acoustic mismatch theory and extended diffusion mismatch model.The results show that the theoretical thermal conductivity of diamond/Cu composites with Ti O₂,Cr₂O₃ and V₂O₅ is 720 W/（m·K）,717 W/（m·K）and 834 W/（m·K）,respectively.However,the actual thermal conductivity of the composites is only 60-65%of the theoretical thermal conductivity.In practice,the actual thermal conductivity of diamond/Cu composites is lower than the theoretical thermal conductivity due to the incompletely dense,the uneven distribution of the transition layer and the difference in the diameter of diamond particles.