Advanced hermetic electronic packaging based on lightweight silicon/aluminum composite produced by powder metallurgy technique

Abstract

Silicon/aluminum (Si/Al) composite is a kind of lightweight electronic packaging material that received a lot of attention in the past 20 years. In this paper, a series of Si/Al composites with lowered coefficient of thermal expansion (CTE) and high thermal conductivity were produced by powder metallurgy (PM). The Si/Al composites are fully dense and have fine Si particles uniquely distributed within pure Al matrix. Three 50%Si/Al composites were designed to have strength in the range of 185–290 MPa to meet different demands, while the other properties keep invariable. Fracture toughness of the composites is measured to be 9–10 MPa·m1/2. The composites were machined to 50%Si/Al housings and 27%Si/Al lids. Both the hermeticities of housings before and after laser-beam-welding sealing are determined. The measured leak rate of composites and sealed housings is in magnitude order of 1 × 10−10 and 1 × 10−9 Pa·m3·s−1, respectively, suggesting high hermeticity. The good hermeticity is attributed to the full dense materials, good weldability, and extremely low weld porosity. The present Si/Al composites are expected to be extensively used in highly hermetic electronic packages.