Tungsten And Copper Electronic Packaging Materials Engineering Research

W/Cu composite is the first consideration in the military electronic device, especialy in the solid phased-array radar, because its component could be adjusted so as to satisfy the requirement of the thermal expansion coefficient(CET) and thermal conductivity(TC).The property of the W/Cu composites which were produced by the Institue of Electronic Packaging Materials of Central South University was comparing to the international standard. But during the large batch production, a lot of new problems appeared, such as the TC was not stable and there were spots in the surface, etc.This article analyzes these problems by making the tungsten article distribution more homogeneous and optimizating the infiltrating process.Furthermore, the microstructure of the composites were observed by using scanning electronic microscopy (SEM). The results showed here:1) The thermal conductivity of the W/Cu composites that were infiltrated 1 hour in the tempretrue of 1350℃ is higher. In addition, the microstructure is more uniform.2) The porosity is an important factor that affects the TC of the composites. The tungsten powder with Fiss particle size 5.6μm, added with 1-2.5% inducing copper powder could be pressed into green compact with high density under large pressure. The electronic packaging material with low porosity could be obtained after infiltrating.3) Copper is the main thermal conducting component in the composites, and its purity affect the TC to a large extension. By using the copper with purity of 99.9%,W/Cu 15 composites with TC of 200W·m^-1·K^-1 could be produced.4) The particle size of the tungsten affected the TC mainly through changing the copper network and the interface. The mix of coarse and fine tungsten is priority to any single one of them considering the pressing and economy.5) The TC of the composite is reducing as the residual stresses of the interface increase. The TC of most products could reach to 180 W-rrf'-K'1 when they were annealed under hydrogen after infiltrating. Furthermore, the data is centralized and property steady.6) The spots that appeared in the surface of the W/Cu composites during production were mainly caused by the tungsten powder distribution before pressing. Much better results could be obtained after the tungsten powder being milled in the ball drum before being pressed.