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在再流焊接期间,封装器件及电路板通过升温区、保温区、焊接区和冷却区。由于热膨胀系数的不同,材料界面处产生热应力。减小热应力能提高焊点与封装器件的可靠性。本文对再流焊期间器件温度场进行数值建模及仿真,获得温度分布及热应力分布;进一步地,以器件在再流焊期间最大热应力为优化目标,以各温区炉温及传送带速率为优化变量,以加热因子、最高温度等为约束条件,采用遗传算法寻优使得最大热应力得到减小。研究结果为再流焊工艺设计提供参考和依据。
During reflow soldering, the packaged devices and circuit boards pass through the temperature rise zone, thermal zone, weld zone, and cooling zone. Due to the different thermal expansion coefficient, thermal stress is generated at the material interface. Reducing thermal stress can increase the reliability of solder joints and packages. In this paper, the numerical simulation and temperature distribution of the device during reflow soldering are carried out to obtain the temperature distribution and the thermal stress distribution. Furthermore, the maximum thermal stress of the device during reflow soldering is taken as the optimization objective. The furnace temperature and the conveyor speed In order to optimize the variables, the heating factor, the maximum temperature and so on are the constraints, and the genetic algorithm is used to optimize so that the maximum thermal stress is reduced. The results provide reference and basis for reflow process design.