Fabrication of Electronic Packaging Grade Cu–W Materials by High-Temperature and High-Velocity Compaction

Abstract

High-velocity compaction (HVC) is a production technique that uses a high-speed punching motion on powder materials to achieve superior mechanical properties. However, as the particle size of the metal powder decreases, achieving higher density becomes increasingly challenging. For this reason, the HVC technique cannot be adopted for manufacturing W85-Cu (85wt% W and 15wt% Cu) heat sinks if the particle size of the tungsten powder is very small [Fisher sub sieve sizer (FSSS) 3 μm or finer]. In this paper, the HVC process at elevated temperature [or high-temperature high-velocity compaction (HTHVC)] was studied for W85-Cu heat sinks. Tungsten skeletons prepared by the conventional uniaxial method were further compacted by HTHVC at various elevated temperatures. The compacted tungsten skeletal blanks were then infiltrated with copper at 1350°C for 2 h. It is concluded that the HTHVC process significantly increases the density of the tungsten skeleton. The distribution of copper in the tungsten skeleton is uniform and no significant clustering is observed in the scanning electron microscopy images, and the resultant W85-Cu material possesses a relative density of 99.5%, hermeticicty of 1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> Pa m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /s, and thermal conductivity of 185 W/(mK). Thus the following conclusions are drawn: 1) overall, the material meets the requirement for heat sinks for electronic packaging applications; and 2) the HTHVC technique is very useful for processing W85-Cu composites for obtaining high-density composites with uniform material distribution and desirable mechanical properties.