Thermal radiation control by surface gratings as an advanced cooling system for electronic devices

Recently, the spectral properties of thermal radiation have been controlled by surface gratings having a size in the optical wavelength range, and this technique has been applied to improve the efficiency of energy systems, e.g., thermophotovoltaic generators and sky radiators. In this paper, the technique was applied to an advanced cooling system for electronic devices. In general, electronic devices are packaged in resin to protect them from damage; however, resin prevents heat from escaping from the package because of resin's strong absorption of thermal radiation in the infrared range and low thermal conductivity. By controlling the spectral property of thermal radiation from electronic devices, the thermal radiation absorbed by resin can be decreased. As a result, a cooling system for electronic devices is possible. At first, we performed a numerical simulation to design the optimal surface gratings to cool electronic devices packaged in epoxy resin. The surface gratings were fabricated using a MEMS process. The performance of the fabricated emitter was evaluated experimentally. In conclusion, we confirmed that this new cooling technique will be effective for electronic devices.