Thermal Management Of High-Power LEDs Through Chip On Thermoelectric Cooler

Light Emitting Diode(LED)is a kind of semiconductor device that can convert electrical energy into light and heat energy,with the advantages of green,noiseless,low power consumption and long service life.However,the photoelectric conversion efficiency of LED is low,only 15-25 % of the electrical energy is converted into light energy,the rest are dissipated in the form of heat energy.In addition,the High-Power LED heat flow density,too high junction temperature will make the LED luminous flux reduction,wavelength red shift,and seriously affect the service life of LED devices.Therefore,the heat dissipation problem of High-Power LEDs is the key to hinder their development.In order to improve the heat dissipation performance of High-Power LED chips,this thesis adopts thermoelectric cooling technology to design an integrated small Thermoelectric Cooler LED package structure from two aspects: LED device package structure and heat dissipation method.Specifically,the main work of this thesis is as follows:(1)A miniaturized,High-Power LED package structure that can be integrated in high density is proposed,and the optimal package structure and parameter dimensions are given by finite element simulation.The thermoelectric simulation results show that the optimal integrated small Thermoelectric Cooler LED package structure has 17 pairs of thermocouples,and the TE thermoelectric legs are rectangular columns with a particle spacing of 0.5 mm,which can effectively dissipate heat from 4 LED chips spaced 4 mm apart at the same time.(2)The fabrication process of High-Power LED package structure based on the small Thermoelectric Cooler for heat dissipation is proposed and implemented,and the heat dissipation performance is compared with the conventional LED chip package structure.The package structure designed in this thesis can reduce the maximum temperature of the LED chip to 16.3 ℃.In terms of optical performance,the LED light output power is maximum when the chip current is 0.8 A.The effectiveness of the integrated small Thermoelectric Cooler LED package structure for heat dissipation is demonstrated.(3)Thermal analysis and experimental tests were conducted on the heat dissipation method of the integrated small Thermoelectric Cooler LED package structure.After the Thermoelectric Cooler reaches the optimal current,a large amount of heat builds up at the hot end and reheating occurs.In this thesis,four heat dissipation methods are used to thermally analyze the package structure,and the results show that only the water-cooling heat dissipation method can mitigate the reheat phenomenon at the hot end of the Thermoelectric Cooler.(4)The effectiveness of the LED package structure with integrated small Thermoelectric Cooler and water-cooling heat dissipation is verified,and the LED chip temperature is reduced by 20 °C compared to the traditional LED package structure.