本文選題：LED驅(qū)動電源 + COB��； 參考：《北京工業(yè)大學(xué)》2015年碩士論文

【摘要】：LED是人類文明歷程上的一個重要的發(fā)明,是追求節(jié)能減排、低碳環(huán)保的有力保障。由于壽命長、效率高、環(huán)保、可靠性高、亮度高等優(yōu)點,LED照明已經(jīng)廣泛應(yīng)用于照明顯示等領(lǐng)域。在未來將會進一步代替?zhèn)鹘y(tǒng)照明方式,因此市場上升空間還很大,人們對LED照明關(guān)注的熱度也不會減弱。與之而來的是不可忽視的可靠性問題。本文針對路燈照明系統(tǒng)對其中的LED驅(qū)動電源和COB光源進行可靠性研究。LED因不能直接使用市電所以必須有專門的驅(qū)動電源為其供電,因此LED驅(qū)動電源質(zhì)量的好壞不僅直接影響整個照明系統(tǒng)的使用情況,還會給燈珠帶來額外的應(yīng)力。COB是高功率和小尺寸發(fā)展的結(jié)果,但散熱問題也隨之而來,如何有效地將熱量及時散發(fā)出去是一個難題。本文針對電解電容在LED驅(qū)動電源失效率高和COB焊料層可靠性的問題,設(shè)計了LED驅(qū)動電源高溫通斷可靠性實驗和COB溫度循環(huán)可靠性實驗。主要有以下工作:一、LED驅(qū)動電源主要包括EMC濾波、PFC轉(zhuǎn)換、PWM控制和DC/DC變換模塊,其中最薄弱的環(huán)節(jié)是DC/DC變換模塊中的濾波電解電容。電解電容在長期的工作中電解液會損耗,進而導(dǎo)致電容量下降,濾波功能退化,出現(xiàn)失效現(xiàn)象。LED驅(qū)動電源一直缺乏統(tǒng)一的標準,這給驅(qū)動電源的考核帶來了難題。本論文在實驗過程中對LED驅(qū)動電源重要參數(shù)進行記錄,得出變化情況,從整體上對驅(qū)動電源做出評估。實驗后針對重點部位解剖驅(qū)動電源,取出電解電容,對電解電容重要參數(shù)進行考核,分析出主要退化原因,對后續(xù)的研究具有重要意義。二、對于COB封裝形式的LED進行了不同溫升和不同功率的退化對比研究。給實驗樣品施加循環(huán)溫度應(yīng)力來進行加速實驗,用不同的電流控制溫升,每組實驗進行了12000次左右的循環(huán)。實驗循環(huán)過程中對光通量和熱阻進行了測量,發(fā)現(xiàn)光通量降低,熱阻增加。實驗后采用非破壞性的結(jié)構(gòu)函數(shù)方法確定了退化的部位,實驗后用X射線、超聲波測量和SEM對內(nèi)部結(jié)構(gòu)進行驗證,發(fā)現(xiàn)芯片外部的引線有燒毀的現(xiàn)象,芯片和熱沉之間的焊料層出現(xiàn)空洞。這與結(jié)構(gòu)函數(shù)方法得出的結(jié)論一致。引線的斷裂是光通量急劇下降的原因,焊料層出現(xiàn)的空洞是熱阻增加的原因。
[Abstract]:LED is an important invention in the course of human civilization.Due to long life, high efficiency, environmental protection, high reliability, high brightness and other advantages, LED lighting has been widely used in lighting display and other fields.In the future will further replace the traditional lighting, so there is still a lot of room for market growth, people's attention to LED lighting heat will not weaken.In contrast, there is a problem of reliability that cannot be ignored.In this paper, the reliability of LED driving power supply and COB light source in street lighting system is studied.Therefore, the quality of LED drive power not only directly affects the use of the whole lighting system, but also brings extra stress to the bead. It is the result of the development of high power and small size, but the problem of heat dissipation also follows.How to effectively release heat in time is a difficult problem.Aiming at the problems of high failure rate of electrolytic capacitor in LED driving power supply and reliability of COB solder layer, the high temperature on-off reliability experiment and COB temperature cycle reliability experiment of LED drive power supply are designed in this paper.The main work is as follows: 1. The main driving power supply includes EMC filter converter PWM control module and DC/DC conversion module. The weakest link is the filter electrolytic capacitance in the DC/DC conversion module.Electrolytic capacitors will lose electrolyte in a long period of work, which will lead to the decrease of capacitance, the degradation of filtering function, the failure phenomenon of LED driving power supply and the lack of uniform standard, which brings problems to the examination of driving power supply.In this paper, the important parameters of LED drive power are recorded in the experiment process, and the changes are obtained, and the overall evaluation of the driving power supply is made.After the experiment, the main parameters of the electrolytic capacitance are examined, and the main reasons of degradation are analyzed, which is of great significance to the subsequent research.Secondly, the degradation of COB LED with different temperature rise and different power is studied.The cyclic temperature stress was applied to the experimental sample to accelerate the experiment. The temperature rise was controlled by different current. About 12000 cycles were carried out in each group of experiments.The luminous flux and thermal resistance were measured during the experimental cycle. It was found that the luminous flux decreased and the thermal resistance increased.After the experiment, non-destructive structural function method was used to determine the degenerated site. After the experiment, X-ray, ultrasonic measurement and SEM were used to verify the internal structure, and it was found that the lead wire outside the chip was destroyed.Holes appear in the solder layer between the chip and the heat sink.This is consistent with the conclusion of the structural function method.The fracture of the lead is the reason of the sharp decrease of luminous flux, and the hole in the solder layer is the reason of the increase of thermal resistance.
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN312.8

【參考文獻】

相關(guān)期刊論文 前1條

1 蔡宣三;開關(guān)電源發(fā)展軌跡[J];電子產(chǎn)品世界;2000年04期

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本文編號：1732896