本文選題：大功率LED + COB封裝　； 參考：《電子科技大學(xué)》2017年碩士論文

【摘要】：發(fā)光二極管(Light Emitting Diode,LED)是由化合物半導(dǎo)體制作而成的發(fā)光器件,是由電子和空穴復(fù)合之后,將電能轉(zhuǎn)換成光的形式激發(fā)釋出。隨著LED額定功率越來越大,LED結(jié)溫也會(huì)變得越來越大,這樣會(huì)導(dǎo)致LED器件壽命變短和出光率變低,所以LED散熱研究是很有必要的。封裝的功能在于提供芯片足夠的保護(hù),防止芯片在空氣中長期暴露或機(jī)械損傷甚至失效。本論文介紹了大功率LED芯片熱設(shè)計(jì)基本理論,基于此理論通過有限元軟件COMSOL建立COB(Chip On Board)封裝的大功率LED的散熱模型,并對其散熱進(jìn)行研究和優(yōu)化。首先,本論文通過COB封裝的大功率LED散熱模型研究了絕緣層對COB封裝的大功率LED熱性能的影響。結(jié)果表明:當(dāng)絕緣層的熱導(dǎo)率從0.5W/(m·K)增大到2.5W/(m·K)時(shí),大功率LED結(jié)溫明顯下降,絕緣層的熱導(dǎo)率此時(shí)對大功率LED結(jié)溫起著決定性的作用。然而,它的熱導(dǎo)率超過6.5W/(m·K),絕緣層熱導(dǎo)率的影響可以忽略。然后,研究不同熱導(dǎo)率下絕緣層厚度對結(jié)溫的影響。結(jié)果表明:當(dāng)絕緣層熱導(dǎo)率小于2.5W/(m·K)時(shí)通過減少絕緣層厚度才能有效地減小大功率LED結(jié)溫。最后,針對絕緣層對大功率LED芯片進(jìn)行了優(yōu)化。第一種優(yōu)化方案:微孔對絕緣層的優(yōu)化;第二種優(yōu)化方案:直接將大功率LED芯片封裝在電絕緣散熱器上面。仿真表明:這兩種方案都具有很好的優(yōu)化效果,在額定功率為11W時(shí),大功率LED芯片結(jié)溫分別降低了28.3℃和13℃。其次,本論文研究了散熱器對多芯片COB封裝的大功率LED模組芯片結(jié)溫的影響。結(jié)果表明:隨著空氣對流傳熱系數(shù)增加,大功率LED芯片最高結(jié)溫呈降低趨勢,空氣對流傳熱系數(shù)在5W/(m~2K)到15W/(m~2K)之間對3×3芯片COB封裝的大功率LED模組最高結(jié)溫降低幅度顯著。然后,研究了芯片距離對芯片結(jié)溫的影響。結(jié)果表明:當(dāng)芯片間距是4.0mm時(shí),3×3芯片COB封裝的大功率LED模組最高結(jié)溫變化幅度已經(jīng)很小,熱耦合現(xiàn)象很弱了。最后,模擬仿真2×8、4×4兩種擺放布局方式下大功率LED模組的溫度場分布圖。結(jié)果表明:2×8擺放布局方式最高結(jié)溫最低,溫度差異最小,2×8芯片COB封裝的大功率LED模組散熱性能比4×4芯片COB封裝的大功率LED模組好。
[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，

本文編號：2079397