| The heat of integrated circuits(IC)has risen severely along with its high integration scale,so higher technology requirement of materials with high thermal conductivity(TC)and low coefficient of thermal expansion(CTE)which match to those of IC materials has been launched.For copper having high-thermal conductivity and high conductivity and fine machining property,zirconium tungstate(ZrW2O8)having isotropic negative thermal expansion(-8.7×10-6K-1).With discussion of the composition design,preparing methods selection and process parameters optimization to synthesis Cu/ZrW2O8 composites with high-thermal conductivity and low thermal expansion coefficient,which as electronic packaging materials will meet requirements IC for new material.High purity cubic phase ZrW2O8 was prepared by solid state reaction.Random shape ZrW2O8 particle pattern was observed with scanning electron microscopy (SEM),High temperature X-ray diffraction(XRD)and Powder X software were used to calculate the lattice constant at different temperatures,and the average value of the coefficient was -5.01×10-6K-1.The ZrW2O8 particles were covered with copper using method by electroless plating In ultrasonic conditions.Phase composition and coating result were characterized by powder X-ray diffraction(XRD)and SEM,The combined TG-DSC technique was carried out to detect the Calories and Weight changes of the coated Cu/ZrW2O8 powders.It was found that the potassium ferrocyanide and 2-2' Bipyridine was used as stabilizer in the process of electroless plating,and Cu2O can be reduced effectively.ZrW2O8 particles surface were covered with nanometer copper when the value of pH was 12.5 and the blue vitriod(CuSO4·5H2O)content was 3.5g/0.2ml and the formalin(HCHO)content was 2.4ml/0.2L,and the proper quantities complexing agent and stabilizer.Improved the reaction speed and resulted in the copper particles size larger with the increase of various parameters.Effect of bath composition on reaction speed and gaining weight were discussed.Discussed the mechanism of production of cuprous oxide and the method of remove it.Cu/ZrW2O8 composites was prepared with powder metallurgic method.Phase constitution of composites which prepared in different pressure was analysed, microscopic structure and cross-section pattern was observed.Density and tightness of Cu/ZrW2O8 composites which different volume content and prepared in different pressure were tested,The results showed that with increase of pressure and Copper content,density and tightness become larger.In this paper,the average CTEs of Cu/ZrW2O8 composite with volume fraction of 45%,55%and 65%ZrW2O8 particles get 9.21×10-6K-1,7.35×10-6K-1,4.85×10-6K-1 respectively in the range of 35～200℃,far greater than the theoretical calculation value. The thermal conductivities of Cu/ZrW2O8 composite increase with growing of copper content,and deceased with increasing temperature. |
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