Design and Analysis of Microchannels for Heat Dissipation of High-Energy VCSELs Based on Laser 3D Printing

Abstract

For the problem of high waste heat in the active area of high-power VCSEL arrays and the difficulty of heat dissipation, we took advantage of laser 3D printing technology and combined it with the relevant principles of fluid-structure coupling, three kinds of microchannel heat sink with different structures of pin-fin, honeycomb, and double-layer reflow were designed. The heat dissipation capacity of three kinds of heat sinks to the heat flux density 200 W/cm2 VCSEL array and the influence of the key characteristics of the microchannel on the heat dissipation capacity was studied. The results show that the double-layer reflow microchannel heat sink has the strongest heat dissipation capability, with the minimum thermal resistance value of 0.258 °C/W when the microchannel diameter and the cooling mass flow rate were 0.5 mm and 24 L/h, respectively. The inner wall roughness of the pure copper microchannel prepared by 3D printing technology was 7.08 μm, and the heat sink thermal resistance was reduced by 0.7% compared with the smooth channel wall. The deviation of the microchannel diameter from the design size (500 μm) was −10 μm, and the heat sink thermal resistance was reduced by 0.8% compared to the theoretical value, which shows that the surface roughness and size deviation of the 3D printed microchannel had beneficial effect on enhancing heat dissipation. The actual thermal conductivity of the 3D printed pure copper after heat treatment was 310.4 W/m-K, at which point the thermal resistance was 0.306 °C/W, and the maximum temperature was 35.3 °C, which satisfied the operating temperature range of the chip. This study provides a theoretical basis and implementation method for the fabrication of heat sinks for high-energy VCSEL arrays using laser 3D printing technology.