Abstract: In order to fabricate high silicon content aluminum alloys electronic packaging materials, Al2O3 and SiO2 dispersion strengthened metallic matrix composites (MMCs) are made by pretreatment of high-energy milling for the Al-Si alloy powder prior to hot-extrusion. The microstructure, density, air tightness, coefficient of thermal expansion and thermal conductivity (TC) are analyzed by using transmission electron microscope (TEM), metallographic microscope and thermal physical testers. Experimental results indicate the following: After Al-Si alloy powders are milled, the material grains, especially Si grains are smaller than those of the high-temperature air oxidation. The material density is close to the theoretical density, and the relative density is about 99%. The air tightness is very good and less than 1nPa•m3•s–1. The coefficient of thermal expansion decreases with prolonging milling time and less than 13K–1 after the powder is milled for 24 h. Thermal conductivity increases with prolonging milling time, after the powder is milled for 32 h, TC is up to 145.5 W•m–1•K–1.

Key words: Al-Si composite material, Electronic packaging, High-energy milling, High-silicon aluminum alloy