功率LED结温和热阻在不同电流下性质研究

通过对不同驱动电流下各种颜色LED结温和热阻测量,发现各种颜色LED的热阻值均随驱动电流的增加而变大,其中基于InGaN材料的蓝光和白光LED工作在小于额定电流下时,热阻上升迅速;驱动电流大于额定电流时,热阻上升速率变缓。其他颜色LED热阻随驱动电流变化速率基本不变。结温也随驱动电流的增加而变大。相同驱动电流下,基于AlGaInP材料的1W红色、橙色LED的结温要低于基于InGaN材料的蓝色、绿色、白色LED的结温。分别用正向电压法和红外热像仪法测量了实验室自制的1 mm×1 mm蓝光芯片结温,比较了两种方法的优缺点。结果表明,电学法测量简单快捷,测量结果可以满足要求。

Research on the Thermal Resistance and Junction Temperature of High-power LEDs

In this paper,the junction temperature and thermal resistance of different color power LEDs were measured at different drive current by forward-voltage method.The colors include red,orange,green,blue and white.The results show that the junction temperature and thermal resistance of different color LEDs increase as the driving current rising.The thermal resistance of blue and white LED based on InGaN materials rise quickly at the low driving current,after the current is more than the operation current,the thermal resistances increase a little bit slowly;and those of the other color LED increase almost the same speed.When the driving current is the same for the same power LED,the higher the thermal conductivity of LED heat sink materials,the lower the LED junction temperature.Comparing with the forward-voltage method,the infrared thermal imaging method is used to measure the junction temperature of 1 W blue LED.The results show the datum of the two methods agrees with each other.