Preparation And Thermal Conductivity Property Of Diamond Composites For Electronic Packaging

The diamond possess characteristics of high thermal conductivity,low coefficient of thermal expansion（CTE）,low density and high degree of electric insulation which makes the diamond composites become potentially one of the best electronic packaging materials.In this study,the sintering process of the glass/diamond composites was studied;The effects of the content and particle size of diamond and additives on the performance of the glass/diamond composites prepared by pressure-less sintering were explored;The glass/diamond,Si/glass/diamond and AlN/diamond composites were prepared at HTHP.The effects of the composition of the composites and the additives on the performances of the composites were explored;The thermal conductivity model of the glass/diamond composites has been modified;The thermal conducting mechanism of the diamond composites and its influence factors have been discussed.The main research achievements are as follows:1.The glass/diamond composites prepared by pressure-less sintering possessed the best insulation and the lowest dielectric constant and loss among the composites prepared in the other ways.These composites also possessed relatively higher thermal conductivity and lower sintering temperature,meeting the preparation and application demands of the LTCC（low temperature co-fired ceramic）;The thermal conductivity of the composites prepared by hot pressing sintering and SPS was improved little,whose electronic properties went down,compared with those prepared by pressure-less sintering;The composites prepared at HTHP possessed the highest thermal conductivity,which can be used for the packaging materials with high requirements of heat dispassion.These composites can also meet the application demand of the electrical packaging materials though with relatively higher dielectric constant,higher dielectric loss and lower electrical resistivity.2.The thermal conductivity of the diamond composites prepared by pressure-less sintering increased at first and then decreased with the increasing addition of CaF₂.The thermal conductivity of the composites with the addition of 6 wt.%CaF₂ was14.59 W·（m·K）^-1 which was 49.49%improved compared with the composites without CaF₂;The performance of the composites was significantly influenced by the addition of the rare earth oxide and the influence of the CeO₂/Y₂O₃ was greater than that of the CeO₂ than that of the Y₂O₃.The thermal conductivity of the composites with the addition of 4 wt.%CeO₂/Y₂O₃ reached 17.57 W·（m·K）^-1 which was 80.02%improved compared with the composites without the addition of CeO₂/Y₂O₃.3.The thermal conductivity of the glass/diamond composites prepared at HTHP increased at first and then decreased with the increasing of the content of diamond and the thermal conductivity reached its maximum value of 118.73 W·（m·K）^-1.The thermal conductivity of the composites increased by 22.44%with the addition of 0.3wt.%CNTs.4.The thermal conductivity of the Si/glass/diamond and AlN/diamond composites reached higher value of 185.41 W·（m·K）^-1 and 193.18 W·（m·K）^-1respectively,and they had good electrical insulation,making up the lack of poor electrical insulation of the metal matrix diamond composites with high thermal conductivity.5.The mechanism and influence factors of thermal conducting of the diamond composites was discussed.The interfacial thermal conductivity of the diamond composites is in the growth area of the variation curve of the thermal conductivity,and the influence of interface thermal resistance on the thermal conductivity of the composites is significant.The thermal conductivity can be efficiently improved by reducting the interface thermal resistance.