【作者】 张爱成；

【导师】 解旭辉；

【作者基本信息】 国防科学技术大学 ， 机械工程， 2005， 硕士

【摘要】 论文中运用ND: YAG激光对同轴激光二极管组件进行焊接封装。这种封装技术最大的缺点是会使激光二极管的封装产生焊后偏移(PWS),很少有一种机械的方法可以校正这种焊后偏移到亚微米级别,目前激光锤被证明是一种很有效的校正方法,激光锤校正作用过程就是利用金属熔化凝固冷却产生的内应力来恢复焊后偏移的过程。论文中建立了激光二极管封装的三维有限元模型,利用通用有限元软件Ansys,编制APDL程序,模拟仿真激光锤在不同焊接参数(电压、脉冲宽度等)的作用过程的温度场、应力场以及焊后偏移校正量。焊接电压和脉宽越大,最高温度越高,热应力影响区越大,同时焊后校正偏移量越大。焊后偏移主要是横向(Y向)的影响,轴向(Z向)变形较小。在同等焊接条件下,横向变形是轴向变形的两倍。在光斑尺寸相同的条件下,高电压小脉宽和低电压大脉宽可以使激光锤校正偏移达到相同的效果,但是高电压小脉宽的焊接参数比低电压大脉宽的焊接参数对材料的热应力影响区要小。所以在其他参数一定的条件下,高电压小脉宽的焊接条件是激光焊接的首选参数。利用激光焊设备对激光锤过程进行了实验研究,同时也验证了有限元仿真的正确性。得到最小焊后偏移量为0.1μm,角度偏移范围为0.0005o~0.005o。角度的偏移也会影响到激光二极管的光通量效率,所以在利用激光锤校正激光二极管封装焊后偏移的过程,要充分考虑横向角度的偏移。当脉冲宽度超过2.5ms时,由于熔池发生了复杂的变化,有可能使激光锤校正方向相反从而难以预测。论文将对利用激光锤技术校正焊后偏移提出合理的参数选择,该研究对利用激光锤技术校正焊后偏移有非常重要的意义。更多还原

【Abstract】 the Nd: YAG laser welding technology is being widely used in To-Can style package for laser diode. However, the disadvantage of laser welding is the so-called post-weld-shift (PWS). The end result is a reduction in light coupling efficiency. The shrinkage force generated by the solidification process is so great that no known mechanical structure can counteract the shrinkage from shifting the joint—at least at the micron level. Laser hammering (LH) was developed to minimize PWS. The laser-hammering process is the technique that utilize the solidification shrinkage to regain the optical throughput lost by PWS.In this paper, a three-dimensional brick element model with temperature-varied material properties was built. An Ansys parametric design language (APDL) was used to simulate the temperature distribution, the distribution of the residual stresses, and PWS in process of laser hammering with variant voltage and pulse width. The fields of Von Misses stress distribution and temperature field distribution expand with voltage and pulse width increasing. At the same time, the correcting valuation of laser hammering increases with the increment of pulse and Voltage. The Y direction is the major shift. At the same welding condition, the shift of Y direction is about two times than that of Z direction.If the weld spot size is the same, the welding- parameter both high voltage, short pulse width and low voltage, long pulse width can get the same PWS of LH. But the range of influence of thermal stress by long pulse is larger than by high voltage. High voltage, short pulse is the preferred welding-parameter in the process of welding packaging.The experimental measurements of LH were in reasonable agreement with the numerical calculations of the finite-element method (FEM) analysis. The min PWS of LH in Y direction is 0.1μm, and the range of angle shift is from 0.0005degree to 0.005 degree. Angle shift can reduce in light coupling efficiency. Therefore, the angle shift is an important factor for light coupling efficiency when PWS is corrected by LH for laser diode packaging. When pulse width is long enough to above 2.5ms, the corrected direction of laser hammering is away from the laser head, which may be the reason for weld bath being fatal destroyed.The purpose of this paper is to present a clear choice of welding-parameter of laser hammering induced fiber alignment shift. The research results obtained by this paper will be helpful to correct the PWS with laser hammering technique.更多还原