Methods for Preparing Graphite Sheets with Piercing Treatment to Enhance Vertical Thermal Conduction

Graphite film was transformed into an effective TIM material by redirecting the in-plane thermal conduction into the cross-plane conduction through piercing mechanism. The piercing action deformed the graphite film into sprout shape, thus redirecting the thermal conduction from horizontal to vertical direction. The effect was further enhanced when graphite was pierced from both directions and the resultant thermal conductivity could be more than doubled vertically. The film thickness was optimal at 250 μm, with pressure for thermal conductivity measurement being optimal at 65 lbf. The optimal piercing density was 15 runs of the rolling, and the optimal length of spike was 0.5 mm. This piercing mechanism can be implemented into roll-to-roll manufacturing process.