基于COB封装的大功率LED芯片散热研究

发布时间：2018-06-28 21:25

  本文选题：大功率LED + COB封装　； 参考：《电子科技大学》2017年硕士论文

【摘要】：发光二极管(Light Emitting Diode,LED)是由化合物半导体制作而成的发光器件,是由电子和空穴复合之后,将电能转换成光的形式激发释出。随着LED额定功率越来越大,LED结温也会变得越来越大,这样会导致LED器件寿命变短和出光率变低,所以LED散热研究是很有必要的。封装的功能在于提供芯片足够的保护,防止芯片在空气中长期暴露或机械损伤甚至失效。本论文介绍了大功率LED芯片热设计基本理论,基于此理论通过有限元软件COMSOL建立COB(Chip On Board)封装的大功率LED的散热模型,并对其散热进行研究和优化。首先,本论文通过COB封装的大功率LED散热模型研究了绝缘层对COB封装的大功率LED热性能的影响。结果表明:当绝缘层的热导率从0.5W/(m·K)增大到2.5W/(m·K)时,大功率LED结温明显下降,绝缘层的热导率此时对大功率LED结温起着决定性的作用。然而,它的热导率超过6.5W/(m·K),绝缘层热导率的影响可以忽略。然后,研究不同热导率下绝缘层厚度对结温的影响。结果表明:当绝缘层热导率小于2.5W/(m·K)时通过减少绝缘层厚度才能有效地减小大功率LED结温。最后,针对绝缘层对大功率LED芯片进行了优化。第一种优化方案:微孔对绝缘层的优化;第二种优化方案:直接将大功率LED芯片封装在电绝缘散热器上面。仿真表明:这两种方案都具有很好的优化效果,在额定功率为11W时,大功率LED芯片结温分别降低了28.3℃和13℃。其次,本论文研究了散热器对多芯片COB封装的大功率LED模组芯片结温的影响。结果表明:随着空气对流传热系数增加,大功率LED芯片最高结温呈降低趋势,空气对流传热系数在5W/(m~2K)到15W/(m~2K)之间对3×3芯片COB封装的大功率LED模组最高结温降低幅度显著。然后,研究了芯片距离对芯片结温的影响。结果表明:当芯片间距是4.0mm时,3×3芯片COB封装的大功率LED模组最高结温变化幅度已经很小,热耦合现象很弱了。最后,模拟仿真2×8、4×4两种摆放布局方式下大功率LED模组的温度场分布图。结果表明:2×8摆放布局方式最高结温最低,温度差异最小,2×8芯片COB封装的大功率LED模组散热性能比4×4芯片COB封装的大功率LED模组好。
[Abstract]:Light emitting diodes (LEDs) are light-emitting devices made from compound semiconductors. After recombination of electrons and holes, the light emitting diodes (LEDs) convert electric energy into light. With the increasing of LED rated power, LED junction temperature will become larger and larger, which will lead to the LED device life shorter and lower luminous rate, so it is necessary to study the LED heat dissipation. The function of packaging is to provide adequate protection against long-term exposure to air, mechanical damage or even failure. In this paper, the basic theory of high power LED chip thermal design is introduced. Based on this theory, the heat dissipation model of COB (Chip on Board) encapsulated high power LED is established by means of finite element software COMSOL, and its heat dissipation is studied and optimized. Firstly, the influence of insulation layer on the thermal performance of COB packaged high power LED is studied by means of the COB encapsulated high power LED heat dissipation model. The results show that when the thermal conductivity of the insulating layer increases from 0.5 W / (m K) to 2.5 W / (m K), the junction temperature of the high-power LED decreases obviously, and the thermal conductivity of the insulating layer plays a decisive role in the junction temperature of the high-power LED. However, its thermal conductivity is more than 6.5 W / (m K), and the influence of insulation thermal conductivity can be neglected. Then, the influence of insulation thickness on junction temperature under different thermal conductivity is studied. The results show that when the thermal conductivity of insulation layer is less than 2.5 W / (m K), the junction temperature of high power LED can be effectively reduced by reducing the thickness of insulation layer. Finally, the high power LED chip is optimized for insulation layer. The first is the optimization of the insulation layer by the microhole, and the second is the direct encapsulation of the high power LED chip on the electric insulation radiator. The simulation results show that the two schemes have good optimization effect. When the rated power is 11W, the junction temperature of high power LED chip is reduced by 28.3 鈩，

本文编号：2079397