Robust Packaging of Vertically Aligned Graphite Substrate by Copper Micro-Rib Structuring

Abstract

Vertically aligned graphite substrate (VGS)–copper packaging was renowned for improving the robustness against the thermal gradient loading by using micro texturing. The micro-groove array with a line width of 50 μm and a pitch of 100 μm was formed into the VGS by controlling the line depth with the use of fast-rate oxygen plasma etching. Three micro-grooved VGS specimens were wet-plated to fill these microgrooves with copper deposits and to cover the VGS surfaces. The nearly full-deposited VGS-Copper specimens were subjected to a severe thermal transient loading test. The simply Cu-covered package and shallow rib-structured VGS-Cu packages were damaged to delaminate at their interfaces. The VGS-Cu package with the copper rib structure with a height of 50 μm experienced no delamination. This rib-structured VGS-copper package with high rib height had sufficient robustness against the severe thermal transients even with the proof of homogeneous thermal spreading capacity.

Heat Transportation by Acicular Micro-Textured Device with Semi-Regular Alignment

“…As discussed in [5][6][7][8], the graphene solid with higher thermal conductivity than copper was utilized as a thermal spreader from the GaN chips to the substrate in order to preserve the integrity of semiconductor packages. In this heat transportation design, higher thermal conductivity than 1000 W/K was fully utilized for fast and homogeneous thermal spreading to prevent the GaN-chipped package from thermal damages.…”

Application of Graphene-Based Materials

“…An example of this can be seen in the work of Badokas and co-workers [24], in which they considered the growth of non-porous, high-quality GaN epilayers on GaN/sapphire templates using different graphene interlayer arrangements, from single layer to triple stack of monolayer graphene, for high-demanding applications such as ultraviolet photodetectors. Somewhat related, as it deals with the development of vertically aligned graphene-based substrates (VGSs) with copper coverage to be used in combination with GaN in field effect transistors, Aizawa et al [25] presented their particular work on enhancing the robustness against thermal gradients of vertically aligned graphene by mechanically anchoring copper rib structures into the micro-grooves of VGSs. The proposed design homogenizes the thermal spreading behavior in heated GaN chips, improving their mechanical integrity and robustness during severe thermal transients.…”