Effect of copper surface roughness on thermal conductance of copper/carbon nanotube array interface

In this work, we demonstrate a systematic study on the contact conductance of Cu/carbon nanotube array interface and the effective thermal conductivity of carbon nanotube array as a function of out-of-plane root-mean-square surface roughness of copper. The rms roughness of Cu was controlled at 0.005, 0.024, 0.065, and 0.192 μm, and the carbon nanotube array was bonded to the controlled Cu surface with In. Using phase sensitive thermal reflectance thermometry, we found that the effective thermal conductivity does not affect by the Cu surface roughness while the contact conductance increased from 0.14 MW/m²-K to 1.2 MW/m²-K as the Cu surface roughness decreased from 0.192 μm to 0.065 μm. Such an increasing trend in contact thermal conductance suggests that the scale of target surface roughness is one of the key factors for CNT arrays based TIMs reach to order of 1 MW/m²K in thermal conductance.