基于有限元的Mini-LED灭灯分析

Analysis of Mini-LED light-off phenomenon based on FEM simulation

Mini-LED背光模组具有精准的局域控光能力且可实现超薄HDR显示,目前其已成为显示行业研究热点之一。针对Mini-LED在点灯过程中发生的灭灯现象,从灯板制作工艺入手,探讨了灭灯现象发生的机理。并基于有限元模拟方法,结合灯板制作工艺、灯板结构等实际情况合理建立了Mini-LED模组仿真模型,模型仿真温度值与实测值对比误差在5%以内。将灯板在高温试验条件下极限状态温度场导入力学仿真模块进行力学模拟,获得极限状态下的热应力值大小及分布,并进一步推算出芯片所受最大推力值。将芯片所受推力值模拟结果与实测结果进行对比后,发现模拟结果位于实测结果的上下四分位数之间,且大于实测结果平均值,符合实际情况。基于模拟结果,改善了芯片锡膏,在芯片最大推力提高15%的情况下,实测芯片推力值的下四分位数值大于模拟值,且Mini-LED灭灯的发生概率从1.13×10^-4降低到了1×10^-5以下,改善效果明显。

On account of its thinner display module and accurate local dimming ability,the Mini-LED technology has become a popular research direction in display field.Aiming at the lighting-off phenomenon through the light board aging process,the reason and mechanism of the lighting-off phenomenon is explored beginning with the manufacture process of the LED board.Based on the FEM simulation method,combined with the manufacture process and the structure of the Mini-LED light board,the simulation model is established reasonably,and the temperature simulation results showed the error of the model is within 5%compared with the measured results.In order to get the thermal stress field of the light board under extreme situation,the simulation result of the light board temperature field under high temperature operation is imported into the mechanics simulation.Compared with the measured results,the simulation result of the maximum chip thrust is between the upper quartile and the lower quartile,and is bigger than the average value of the measured results,which show the simulation is accord with the actual situation.The solder paste is developed based on the simulation,and the result shows that the probability of the light-off phenomenon is reduced to under 1×10^-5 from 1.13×10^-4 when the maximum chip thrust is increased by 15%,which shows the improvement effect is obvious.