功率型LED结温检测与ANSYS仿真分析

发布时间：2018-01-14 12:45

本文关键词：功率型LED结温检测与ANSYS仿真分析　出处：《杭州电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：LED(light emitting diode,发光二极管)是一种可将电能转变为光能的半导体发光器件,本文主要围绕LED结温热问题所引起的光电特性影响而展开研究,主要提出间接LED结温测试方案与ANSYS仿真分析。间接式LED结温测试方案主要采用电压法测量结温的原理,由半导体伏安特性关系式和反向饱和电流关系式,推导出LED结温与正向电压存在近似线性关系,即电压法的原理推导。基于这个原理,采用最小二乘法线性拟合求出小电流下的K系数值,并求出结温。通过对同一批次同一型号的LED器件进行K系数值测试,证实具有相同制造工艺的同一批次同一型号LED的K系数值很接近,K系数最大最小差值仅为5.7%。论文对小电流结温测试中存在的不足进行相关阐述,提出大电流LED结温测试方案,大电流LED结温测试方案基于LED瞬态热学方程式,根据瞬态热学方程式推算出LED导通的初始电压,并与结温进行拟合得到大电流下的K系数值,根据此K系数值计算出最后的工作结温。实验对六组功率型LED样品分别进行小电流结温测试、大电流结温测试和红外热成像测试,通过对测试结果进行比较分析,证实大电流测试方案的可行性。ANSYS仿真分析主要是结合Pro/E强大的建模功能和ANSYS完善的热分析功能,模拟分析LED器件温度分布。采用薄膜铂电阻精确测量LED器件局部温度,根据局部温度确定ANSYS热仿真中的空气对流系数的取值,从而使得仿真结果更加准确。将此方法分别与标准电压法和红外热像法实测结温结果作对比,利用该方法获得的仿真结果与电压法和红外热像法实测结果具有很好的一致性,实验结果说明模型建立和ANSYS仿真分析过程是正确的,证实ANSYS热仿真分析可以作为一种有效的LED结温估测方法。同时利用ANSYS有限元热仿真法还分析了三芯片COB封装LED温度分布,证实在透明硅胶区域范围内,随着芯片间距的不断增大,三芯片表面温度分布越来越均匀,其最高芯片结温也随着芯片间距的增大而变小。
[Abstract]:LED(light emitting diode is a semiconductor light-emitting device that can convert electrical energy into light energy. This paper focuses on the influence of the photoelectric characteristics caused by the temperature and heat problem of LED junction. Indirect LED junction temperature measurement scheme and ANSYS simulation analysis are put forward. Indirect LED junction temperature measurement scheme mainly adopts the principle of voltage method to measure junction temperature. An approximate linear relationship between the temperature and the forward voltage of the LED junction is derived from the relationship between the volt-ampere characteristic of the semiconductor and the reverse saturation current, that is, the principle of the voltage method. The value of K coefficient and junction temperature are obtained by using the least square linear fitting method. The K coefficient values of the same batch and the same type of LED devices are tested. It is proved that the K coefficient value of the same batch and same type LED with the same manufacturing process is very close to the maximum and minimum difference of K coefficient of the same batch is only 5.7. the deficiency of the small current junction temperature test is expounded in this paper. A high current LED junction temperature measurement scheme is proposed. The high current LED junction temperature measurement scheme is based on the LED transient thermal equation, according to the transient thermal equation to calculate the initial voltage of LED conduction. The value of K coefficient under high current is obtained by fitting with junction temperature, and the final working junction temperature is calculated according to the value of K coefficient. Six groups of power type LED samples are tested with small current junction temperature. High current junction temperature test and infrared thermal imaging test, through the test results are compared and analyzed. It is proved that the feasibility of high current test scheme... ANSYS simulation analysis is mainly combined with the powerful modeling function of Pro/E and the perfect thermal analysis function of ANSYS. The temperature distribution of LED device is simulated and analyzed. The local temperature of LED device is accurately measured by thin film platinum resistance, and the value of air convection coefficient in ANSYS thermal simulation is determined according to the local temperature. So that the simulation results are more accurate. The method is compared with the results measured by standard voltage method and infrared thermal image method respectively. The simulation results obtained by this method are in good agreement with the measured results by the voltage method and the infrared thermal image method. The experimental results show that the modeling and ANSYS simulation are correct. It is proved that ANSYS thermal simulation can be used as an effective method to estimate the junction temperature of LED, and the LED temperature distribution of three-chip COB package is also analyzed by using ANSYS finite element method. It is proved that in the region of transparent silica gel, with the increasing of chip spacing, the surface temperature distribution of the three chips becomes more and more uniform, and the highest chip junction temperature becomes smaller with the increase of chip spacing.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8

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