Experimental study on substrate with hierarchical nested channels for thermal interface resistance control

Abstract

Thermal interface resistance is an important parameter for the thermal management of electronics packaging. In order to reduce thermal interface resistance, hierarchical nested channels were designed and fabricated on the surfaces of aluminum and copper sheets. Experiments were conducted to measure the thermal interface resistance of the sheets. A sequence of experimental results revealed that thermal interface resistance of the sheets with hierarchical nested channels is 2−3 times larger than that of the original flat sheets without the channels, which is contrary to the experimental objective. A comprehensive experimental analysis was presented to explain the phenomenon. It is found that the roughness of contact interface plays a key role. In the reported references, the thermal interface material composed of metal particles is easy to form particle stacking in the smooth contacting surface, therefore, the hierarchical nested channels can effectively reduce the particle stacking and the corresponding thermal interface resistance. However, in the present experiment samples, the surface roughness is larger than 10 μm, the phenomenon of particle stacking is difficult to occur, the hierarchical nested channels cannot perform well for decreasing particle stacking and thermal resistance. Otherwise, the hierarchical nested channels increases the bulk thermal resistance because of the replacement of the high thermal conductivity metal material with thermal greases that have relatively low thermal conductivity.