流體對流下大功率LED散熱性能研究
發(fā)布時間：2018-08-11 18:26
【摘要】：發(fā)光二極管(Light Emitting Diode,LED)具有節(jié)能、環(huán)保、體積小、壽命長、耐沖擊、可靠性高、響應速度快等優(yōu)點,被稱為第四代新型綠色照明光源。隨著LED在照明領域的應用發(fā)展,高功率、高亮度、高品質的LED已經成為重要的發(fā)展趨勢。然而,目前LED的電光轉換效率還較低,隨著輸入功率的增大,散熱對LED器件的影響也越來越明顯。結溫的升高,導致發(fā)光波長發(fā)生偏移、光通量和使用壽命降低,所以LED的熱管理對器件的整體性能起著至關重要作用,如何提高大功率LED器件的散熱性能是其發(fā)展道路上亟待解決的關鍵技術之一。要獲得高品質、高功率的LED,就必須理解LED熱沉結構的散熱原理,改進大功率LED封裝結構。在大功率LED封裝的散熱設計上,最重要的是有效降低LED芯片的結溫和熱阻,通過設計合理的散熱結構,增加器件的整體散熱量。LED芯片的熱量主要是先通過熱傳導傳遞到散熱器,再通過熱對流與外界環(huán)境進行交換,因為在固體與流體之間存在熱邊界層,所以如何減小邊界層厚度,是增加LED散熱性能的關鍵因素。因此,對大功率LED封裝結構進行研究,有利于提高大功率LED器件整體散熱性能,加快半導體照明時代的進程。文中采用理論分析與計算機仿真模擬分析相結合的方法,研究了熱沉結構對LED散熱性能的影響。其中,在自然對流條件下設計了新型散熱結構,在液冷條件下,探究了不同結構熱沉的散熱機理。分析結果表明:(1)開縫基板能有效改善流場分布,提高表面換熱系數(shù),增加散熱性能。在傳導和對流的雙重作用下,存在最佳縫間距使結溫和熱阻最低,輸入功率為1 W時,結溫和熱阻分別降低3.2 K和1.01 K/W。隨芯片輸入功率的增加,開縫基板的散熱效果愈發(fā)明顯。同時,開縫基板的提出也節(jié)省了器件封裝成本。(2)在開縫基板且散熱體積相同的條件下,存在最佳翅片數(shù)量使LED散熱性能最好,翅片數(shù)量為6時,結溫最低,為345.970 K。(3)運用30°角矩形翅片的LED結溫和器件熱阻最低,換熱性能最好,即速度場與溫度場之間的協(xié)同性最好;菱形翅片次之,垂直平行翅片最差。30°角矩形翅片和菱形翅片由于傾斜角的存在,在增加換熱性能的同時也增加了流動阻力,即速度與速度梯度之間的協(xié)同性變差;綜合分析換熱性能和流動阻力,菱形翅片的綜合換熱性能最好。封裝散熱結構的設計和散熱原理的分析,對提高大功率LED散熱性能具有極其重要的意義。研究大功率LED封裝結構及其散熱性能,對改進大功率LED封裝具有一定的指導意義,為解決大功率LED的散熱問題提供了新的途徑。
[Abstract]:Light emitting diode (Light Emitting) has the advantages of energy saving, environmental protection, small size, long life, high impact resistance, high reliability and fast response, etc. It is called the fourth generation green lighting source. With the development of LED in the field of lighting, high power, high brightness, high quality LED has become an important development trend. However, the electro-optic conversion efficiency of LED is still low. With the increase of input power, the effect of heat dissipation on LED devices is becoming more and more obvious. The increase of junction temperature leads to the shift of luminous wavelength, the decrease of luminous flux and service life, so the thermal management of LED plays an important role in the overall performance of the device. How to improve the heat dissipation performance of high power LED devices is one of the key technologies to be solved. In order to obtain high quality and high power LED, it is necessary to understand the heat dissipation principle of LED heat sink structure and improve the high power LED package structure. In the heat dissipation design of high power LED packaging, the most important thing is to effectively reduce the junction and thermal resistance of LED chip. By designing a reasonable heat dissipation structure, the overall heat dissipation of the device can be increased. The heat of the chip is mainly transferred to the radiator by heat transfer. Because there is a thermal boundary layer between solid and fluid, how to reduce the thickness of boundary layer is the key factor to increase the heat dissipation performance of LED. Therefore, the research of high power LED packaging structure is helpful to improve the overall heat dissipation performance of high power LED devices and speed up the process of semiconductor lighting era. In this paper, the influence of heat sink structure on the heat dissipation performance of LED is studied by combining theoretical analysis with computer simulation analysis. Among them, a new heat dissipation structure was designed under natural convection, and the heat sink mechanism of different structures was explored under liquid cooling conditions. The results show that: (1) the slit substrate can effectively improve the flow field distribution, increase the surface heat transfer coefficient and increase the heat dissipation performance. Under the dual action of conduction and convection, the optimum gap spacing makes the thermal resistance of junction temperature minimum. When the input power is 1 W, the thermal resistance of junction and temperature decreases by 3.2 K and 1.01 K / W, respectively. With the increase of chip input power, the heat dissipation effect of slit substrate becomes more and more obvious. At the same time, the proposed slit substrate also saves the packaging cost of the device. (2) under the same heat dissipation volume of the slit substrate, the optimal number of fins makes the heat dissipation performance of LED the best, the number of fins is 6, and the junction temperature is the lowest. For 345.970 K. (3) the thermal resistance of LED junction and temperature field is the lowest, and the heat transfer performance is the best, that is, the synergy between velocity field and temperature field is the best, and the rhomboid fin is the second. The perpendicular parallel fin has the worst .30 擄angle rectangular fin and rhomboid fin, which increases the heat transfer performance and increases the flow resistance at the same time, that is, the synergy between velocity and velocity gradient becomes worse. Comprehensive analysis of heat transfer performance and flow resistance, the rhomboid fin comprehensive heat transfer performance is the best. The design of package heat dissipation structure and the analysis of heat dissipation principle are of great significance to improve the heat dissipation performance of high power LED. The research on the high power LED packaging structure and its heat dissipation performance has a certain guiding significance for improving the high power LED packaging, and provides a new way to solve the heat dissipation problem of the high power LED.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN312.8
本文編號：2177847
[Abstract]:Light emitting diode (Light Emitting) has the advantages of energy saving, environmental protection, small size, long life, high impact resistance, high reliability and fast response, etc. It is called the fourth generation green lighting source. With the development of LED in the field of lighting, high power, high brightness, high quality LED has become an important development trend. However, the electro-optic conversion efficiency of LED is still low. With the increase of input power, the effect of heat dissipation on LED devices is becoming more and more obvious. The increase of junction temperature leads to the shift of luminous wavelength, the decrease of luminous flux and service life, so the thermal management of LED plays an important role in the overall performance of the device. How to improve the heat dissipation performance of high power LED devices is one of the key technologies to be solved. In order to obtain high quality and high power LED, it is necessary to understand the heat dissipation principle of LED heat sink structure and improve the high power LED package structure. In the heat dissipation design of high power LED packaging, the most important thing is to effectively reduce the junction and thermal resistance of LED chip. By designing a reasonable heat dissipation structure, the overall heat dissipation of the device can be increased. The heat of the chip is mainly transferred to the radiator by heat transfer. Because there is a thermal boundary layer between solid and fluid, how to reduce the thickness of boundary layer is the key factor to increase the heat dissipation performance of LED. Therefore, the research of high power LED packaging structure is helpful to improve the overall heat dissipation performance of high power LED devices and speed up the process of semiconductor lighting era. In this paper, the influence of heat sink structure on the heat dissipation performance of LED is studied by combining theoretical analysis with computer simulation analysis. Among them, a new heat dissipation structure was designed under natural convection, and the heat sink mechanism of different structures was explored under liquid cooling conditions. The results show that: (1) the slit substrate can effectively improve the flow field distribution, increase the surface heat transfer coefficient and increase the heat dissipation performance. Under the dual action of conduction and convection, the optimum gap spacing makes the thermal resistance of junction temperature minimum. When the input power is 1 W, the thermal resistance of junction and temperature decreases by 3.2 K and 1.01 K / W, respectively. With the increase of chip input power, the heat dissipation effect of slit substrate becomes more and more obvious. At the same time, the proposed slit substrate also saves the packaging cost of the device. (2) under the same heat dissipation volume of the slit substrate, the optimal number of fins makes the heat dissipation performance of LED the best, the number of fins is 6, and the junction temperature is the lowest. For 345.970 K. (3) the thermal resistance of LED junction and temperature field is the lowest, and the heat transfer performance is the best, that is, the synergy between velocity field and temperature field is the best, and the rhomboid fin is the second. The perpendicular parallel fin has the worst .30 擄angle rectangular fin and rhomboid fin, which increases the heat transfer performance and increases the flow resistance at the same time, that is, the synergy between velocity and velocity gradient becomes worse. Comprehensive analysis of heat transfer performance and flow resistance, the rhomboid fin comprehensive heat transfer performance is the best. The design of package heat dissipation structure and the analysis of heat dissipation principle are of great significance to improve the heat dissipation performance of high power LED. The research on the high power LED packaging structure and its heat dissipation performance has a certain guiding significance for improving the high power LED packaging, and provides a new way to solve the heat dissipation problem of the high power LED.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN312.8
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