Preparation Of Advanced Electronic Packaging Complex Material-Cu/ZrW₂O₈

With the development of quasi-conductor industry, heat-producing capability of electronic component increase greatly, which requires for high hot property of packaging material. Namely low coefficient of thermal expansion that match with Si or GaAs, at the meantime, hold high coefficient of heat conductivity. Therefor, metal, metallic composite and oxide as new technology and process of packaging material has been put on the agenda. This paper focuses on the synthesis of negative thermal expansion materials ZrW₂O₈ which composite with Cu to prepare late-model electronic packaging material with expansion coefficient controllable.Negative thermal expansion (NTE) material becomes a new branch of materials science in recent years. This paper makes use of high coefficient of thermal conductivity of copper and NTE property of ZrW₂O₈ to prepare Cu-ZrW₂O₈ complex material to meet previous requirements of performance. At the same time, in order to improve the disperse of ZrW₂O₈ in copper matrix, modify the out phase of Cu-ZrW₂O₈; reduce interface stress, Cu-coated ZrW₂O₈ powders were prepared using heterogeneous precipitation and chemical plating method. This composite powder was used as starting material to prepare complex material which were studied in this paper.ZrW₂O₈ powders were prepared using the improved solid state reaction by ZrC>2 and WO3 powders which were used as raw materials. The influence of reaction temperature on the particle size and the negative thermal coefficient were studied. The size of powder that prepared by improved solid state reaction is smaller than that of traditional method, the value of it is 1×2μm. The influence of reaction temperature on the particle size and the negative thermal coefficient were studied. Thermal dilatometer showed that from room-temperature to 160℃, coefficient of thermal expansion is -8.51×10^-6K^-1, from 200℃to 700℃, coefficient of thermal expansion is -2.44×10^-6K^-1. In the whole temperature interval, coefficient of thermal expansion is -3.81×10^-6K^-1Cu-coated ZrW₂O₈ powders were prepared using heterogeneous precipitation and chemical plating method. In the study of heterogeneous precipitation, the influence of reaction liquid concentration and droping method were studied, the influence of different surface active agent on effect of composite powder were also studied; in the study of chemical plating, the influence of pH value, main salinity, reductant concentration, complexing agent concentration, loading capacity were studied. The morphology of composite powders was detected by X-ray diffraction (XRD) and characterized by Scanning electron microscopy (SEM).Cu-ZrW₂O₈ composite was using prepared composite powder with chemical plating method as starting material. The influence of different temperature and pressing pressure effect on density and contexture were studied and compare mixed-powder with coated-powder. XRD show under 400℃2h sintering with H₂ shielding gas can precent decomposition of ZrW₂O₈. The composite surface and fracture surface was detected by SEM. Heat expansion performance of different ZrW₂O₈ mass ratio was studied. The coefficient of thermal expansion can be controlled by add in...