为获得适用于电子封装的W-Cu材料,对60W-40Cu、70W-30Cu、75W-25Cu和80W-5Ni-15Cu合金进行选区激光熔化实验,研究了W含量对合金微观组织、致密度、热导率、热膨胀系数、表面粗糙度、硬度的影响。结果显示:4种W-Cu合金的成形表面均存在球化现象;当W的质量分数低于70%时,致密化机制为重排致密,W相间几乎不发生连接与团聚,热传导优先在铜相中进行;随着W的质量分数上升到75%,致密化机制主要为固态烧结,热传导路径由以W相为核心、边缘由Cu相包裹的结构单元组成;随着W含量增加,W-Cu合金的热导率和热膨胀系数与理论值的偏差增大,合金的表面粗糙度、硬度均增加。最终获得60W-40Cu、70W-30Cu、75W-25Cu、80W-5Ni-15Cu成形后的致密度分别为97.9%,94.5%,91.6%,91.9%,热导率分别为210.4,176.8,152.7,121.3 W·K ^-1·m ^-1,热膨胀系数分别为11.05×10 ^-6,9.33×10 ^-6,8.17×10 ^-6,7.02×10 ^-6 ℃ ^-1,表面粗糙度分别是9.2,13.7,15.2,15.4 μm,显微硬度分别是183,324,567,729 HV。

This study obtains W-Cu materials suitable for the electronic packaging by fabricating W-Cu composites with different W contents (such as 60W-40Cu, 70W-30Cu, 75W-25Cu, and 80W-5Ni-15Cu) through selective laser melting. The effect of W content on the microstructure, density, thermal conductivity, coefficient of thermal expansion, roughness, and hardness is evaluated. The results show that the balling phenomenon is common in such four composites. When the W mass fraction is less than 70%, the densification mechanism is rearrangement; connection and contiguity are hardly observed between W phases; heat conduction is preferred in the Cu phases. In addition, when the W mass fraction is higher than 75%, solid sintering is the main densification mechanism, and the heat conduction path contains the constitutional unit of Cu occupying the unit edges and W occupying the unit center. The deviation between the thermal conductivity/coefficient of thermal expansion of W-Cu composites and the theoretical values increases with increasing W content, which also occurs in the cases of roughness and hardness. The obtained densities of 60W-40Cu, 70W-30Cu, 75W-25Cu, and 80W-5Ni-15Cu are 97.9%, 94.5%, 91.6%, and 91.9%, respectively. The thermal conductivities of the four composites are 210.4, 176.8, 152.7, and 121.3 W·K -1·m -1, respectively. Furthermore, the thermal expansion coefficients of the four composites are 11.05×10 -6, 9.33×10 -6, 8.17×10 -6, and 7.02×10 -6 ℃ -1, respectively. The surface roughnesses of the four composites are 9.2, 13.7, 15.2, and 15.4 μm, and the microhardnesses are 183, 324, 567, and 729 HV, respectively.