Enhanced Thermal Performance Copper/Tungsten Metal Composites

摘要

Copper matrix composites, using tungsten or molybdenum as reinforcement, provide good thermal dissipation and thermal expansion match to package Si or GaAs dice for microelectronic and optoelectronic applications. Copper/tungsten (Cu/W) composite materials exhibiting enhanced thermal conductivity exceeding 200 W/mK with coefficient of thermal expansion of 7.1 ppm/°C have been developed for packaging purposes. Refinements in the chemical composition, keeping the same homogeneous fine grained microstructure, characteristic to the powder metallurgy based process, have resulted in remarkable improvements in thermal performance for the isotropic materials. Recent developments using Functionally Graded Materials (FGM) designs, have allowed for an effective thermal conductivity of more than 300 W/mK at the same time that effective coefficient of thermal expansion has been kept in between 5.3 and 7.1 ppm/°C. The thermal performance of the anisotropic composite parts has been pushed to a level close to that of pure copper. This paper describes the experimental results obtained after thermal performance evaluation and other details of FGM Cu/W technology developed.