光纤激光切割蓝宝石基片的工艺研究

Study on Fiber Laser Cutting of Sapphire Substrate

采用波长为1070 nm的光纤激光对蓝宝石基片进行切割加工。研究了蓝宝石基片切割过程中,蓝宝石基片下表面产生粉末物质和崩边的原因,并分析了激光加工工艺参数(激光能量密度、切割速度、重复频率、辅助气体压力)与蓝宝石基片上下表面崩边尺寸的关系。研究结果表明:光纤激光与蓝宝石之间的相互作用主要是光热作用,蓝宝石材料吸收激光能量后发生熔化、气化现象。同时,伴随辅助气体N2被击穿后产生的等离子体对激光的吸收,在蓝宝石内部出现了钥匙孔现象,钥匙孔的长度对切割质量有较大的影响。综合考虑激光切割蓝宝石基片工艺参数以及辅助气体压力等因素,激光能量密度为5.7×103J/cm2、切割速度为6 mm/s、重复频率为1.8 k Hz、N2压力为0.9 MPa时,获得了厚度为0.31 mm的蓝宝石基片,上表面崩边为3 mm,下表面崩边为8 mm。

A fiber laser with wavelength of 1070 nm is employed to cut the sapphire substrate. The reasons for the generation of powder materials on the sapphire substrate surface and the collapse edge during the laser cutting sapphire substrate are researched, and the relation between the laser processing parameters （laser fiuence, cutting velocity, repetition frequency, the pressure of assistant gas） and the collapse edge size on both sides of sapphire substrate is analyzed. The results show that the interaction between laser and sapphire is mainly thermal effect, which makes the sapphire material melt and evaporate. With the absorption of plasma which is produced by nitrogen for laser, the phenomenon of keyhole appears inside the sapphire structure and the length of keyhole have a significant effect on cutting quality. When the sapphire which thickness is 0.31 mm cut by laser, the collapse edge size on the sapphire substrate surface is 3 μm, and collapse edge size under the surface is 8 pm with the optimized laser processing parameters, that laser fluence is 5.7 ×10^3J/cm^2, cutting velocity is 6 mm/s, repetition fre0uencv is 1.8 kHz. the nressure of assistant gas is 0.9 MPa.