Thermal Radiative Copper Oxide Layer for Enhancing Heat Dissipation of Metal Surface

Abstract

The heat dissipation of a metal heat sink for passive cooling can be enhanced by surface modifications to increase its thermal emissivity, which is reflected by a darker surface appearance. In this study, copper electrodeposition followed by heat treatment was applied to a copper substrate. The heat treatment formed a nanoporous oxide layer containing CuO and Cu2O, which has a dark blackish color and therefore increased the thermal emissivity of the surface. The heat dissipation performance was evaluated using the sample as a heat sink for an LED module. The surface-treated copper heat sink with a high thermal emissivity oxide layer enhanced the heat dissipation of the LED module and allowed it to be operated at a lower temperature. With an increase in the heat treatment, the thermal emissivity increases to 0.865, but the thermal diffusivity is lower than the copper substrate by ~12%. These results indicate that the oxide layer is a thermal barrier for heat transfer, thus optimization between the oxide thickness and thermal emissivity is required by evaluating heat dissipation performance in operating conditions. In this study, an oxide layer with an emissivity of 0.857 and ~5% lower thermal diffusivity than the copper substrate showed the lowest LED operating temperature.

Measurement of Downwelling Radiance Using a Low-Cost Compact Fourier-Transform Infrared System for Monitoring Atmospheric Conditions

“…To measure the atmospheric emitted radiance spectrum and derive atmospheric thermal dynamic profiles, we constructed a compact FTIR observing system using the M4400 spectrometer (Midac Corporation, Irvine, CA, USA). Previously, the MIDAC M4400 spectrometer was primarily used to measure the surface emissivity [22,23] or column gas composition in an open-path FTIR system [24]. Unlike them, we build an additional frontend optical part to the FTIR instrument to acquire atmospheric infrared signals, as shown in Figure 2 (the compact FTIR environment is shown in Figure S1).…”