A diamond-like carbon (DLC) film, coated on a AISI420-J2 stainless steel substrate and vertically aligned graphite (VAG), was structured by high-density plasma oxidation to work as a DLC-punch for micro-stamping and DLC-nozzle array for micro-dispensing, in addition to acting as a copper-plated thermal spreader, respectively. Thick DLC films were micro-patterned by maskless lithography and directly plasma-etched to remove the unmasked regions. Thick VAG (Ca plates were micro-patterned by screen-printing and selectively etched to activate the surface. Raman spectroscopy as well as electric resistivity measurement proved that there was no degradation of VAG by this surface activation. Wet plating was utilized to prove that copper wettability was improved by this surface treatment.
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.
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