关键词: 飞秒激光, 金刚石, 微通道热沉, 微通道尺寸, 截面形貌

Abstract: In order to study the processing problems of the diamond micro-channel heat sinks of the radar power module, the femtosecond laser processing research of polycrystalline diamond micro-channel was carried out. The temperature field distribution and removal processes of diamond irradiated by femtosecond laser were simulated. The ablation threshold of the diamond was studied theoretically and experimentally. The influences of parameters such as laser energy, scanning speed, scanning times, focus position, and optimized parameter on the size of diamond microgrooves were investigated. The results show that the highest temperature of diamond may exceed the gasification temperature of material removal when the power of femtosecond laser is greater than 0.3 W. The highest temperature is in the center of the spot, and the power does not change the distribution of temperature field. The ablation threshold of femtosecond laser processing diamond is as 1.8 J/cm2. The depth of diamond microgrooves is positively correlated with laser power and scanning times, negatively correlated with scanning speed, and basically symmetrically distributed with positive and negative defocus. In addition, the surface width of diamond microgrooves does not change obviously. Under the optimized parameters of laser power of 5 W, scanning speed of 100 mm/s, scanning times of 30 and defocusing amount of -0.5 mm, the diamond micro-grooves have regular structure. The taper of side wall of sectional morphology is controlled within 3° and there are no defects such as residue, crack and edge collapse on the surfaces. There are no cracks in the inner part of micro-channels which have high consistency. The ‘cold’ machining of diamond material may realize, and the requirements of high-quality machining for micro-channels of diamond heat sinks in radar power components may be satisfied.

Key words: femtosecond laser, diamond, micro-channel heat sink, micro-channel size, sectional morphology