基于微通道致冷的大功率LED阵列封装热分析

采用微通道致冷技术,设计了大功率LED阵列封装的微通道致冷结构,并应用热分析软件模拟了其热性能,探讨不同鳍片结构尺寸、流速、功率等参数对LED多芯片散热效果的影响.文中提出了采用交错通道以提高LED封装的散热能力,模拟结果显示,交错微通道致冷的封装结构能很好地满足大功率LED阵列的散热需要.     

基于COB技术的LED散热性能分析

当前,散热问题已成为影响LED寿命、光效、光衰和色温等技术参数的重要因素。文章在综合分析散热技术和LED封装对散热性能影响的基础上,利用COB(板上芯片)封装技术,将LED芯片直接封装在铝基板上,研制成了一种基于COB封装技术的LED。与SMD封装LED进行比较,分析了其散热性能。分析结果表明:基于COB封装技术的LED减少了LED器件的结构热阻和接触热阻,使其具有良好的散热性能。     

大功率LED低热阻封装技术进展

散热是大功率LED封装的关键技术之一,散热不良将严重影响LED器件的出光效率、亮度和可靠性。影响LED器件散热的因素很多,包括芯片结构、封装材料(热界面材料和散热基板)、封装结构与工艺等。文章具体分析了影响大功率LED热阻的各个因素,指出LED散热是一个系统概念,需要综合考虑各个环节的热阻,单纯降低某一热阻无法有效解决LED的散热难题。文中还对国内外降低LED热阻的最新技术进行了介绍。     

大功率LED封装有限元热分析

介绍了有限元软件在大功率LED封装热分析中的应用,对一种多层陶瓷金属(MLCMP)封装结构的LED进行了热模拟分析,比较了不同热沉材料的散热性能,模拟了输入功率以及强制空气冷却条件对芯片温度的影响.结果表明当达到热稳态平衡时,芯片上的温度最高,透镜顶部表面的温度最低,当输入功率达到3 W时,芯片温度超过了150℃,强制空冷能显著改善器件的散热性能.     

压接式GCT封装的热特性分析

电力半导体器件的散热性能和热可靠性与其封装结构密切相关,选择合适的封装结构对改善器件的散热性能和提高热可靠性非常重要。文中根据压接式GCT器件封装结构特点,采用ANSYS软件利用有限元法分析了单芯片封装和多芯片封装结构的温度及热机械应力分布,并与常规的焊接式封装进行了对比。结果表明,压接式封装结构的散热效果比焊接式封装结构稍差,但其芯片上产生的热机械应力明显减小。多芯片封装采用常规的风冷散热器时芯片温度已经超过了器件的安全工作温度(125℃),应该采用热管散热器才能保证器件可靠地工作。     

远程荧光LED球泡灯热仿真分析

采用FloEFD流体分析软件分析了改变LED散热器翅片数和基板厚度对LED球泡灯热量的影响。首先对LED芯片进行仿真,然后用蓝宝石替换LED芯片其他部分简化后仿真,将两者进行了对比。接着对远程荧光LED集成封装光源进行了热模拟,发现将大功率芯片集成在铝基板上,工作时产生的热量非常大,模拟时芯片的结温在159.9℃,超过了LED正常工作结温,所以仅仅依靠铝基板难以达到散热要求。最后对LED球泡灯散热器不同翅片数和不同基板厚度分别进行了热仿真,得出当翅片数为16,基板厚度为2mm时,LED球泡灯的整体散热良好,模拟结果显示LED芯片的温度只有83.8℃,完全满足散热要求。     

基于共晶焊接工艺和板上封装技术的大功率LED热特性分析

采用ANSYS有限元热分析软件,模拟了基于共晶焊接工艺和板上封装技术的大功率LED器件,并对比分析了COB封装器件与传统分立器件、共晶焊工艺与固晶胶粘接工艺的散热性能。结果表明:采用COB封装结构和共晶焊接工艺能获得更低热阻的LED灯具;芯片温度随芯片间距的减小而增大;固晶层厚度增大,芯片温度增大,而最大热应力减小。同时采用COB封装方式和共晶焊接工艺,并优化芯片间距和固晶层厚度,能有效改善大功率LED的热特性。     

硅衬底结构LED芯片阵列封装热可靠性分析

LED阵列封装是高密度电子封装的解决方案之一,LED的光集成度得到提高,总体输入功率提高,但同时其发热量大,封装结构如果不合理,那么在温度载荷下各层材料热膨胀系数的差异将会导致显著的热失配现象,从而将会大大缩短LED的寿命。为此,兼顾散热和封装的可靠性设计与表面贴装式将芯片直接焊接在铝基板上不同的是采用硅衬底过渡,同时在硅衬底上布置电路这一结构。这种结构的优点是可以通过硅衬底的过渡来降低热失配对封装结构的影响,同时硅衬底作为电路层则省去了器件引脚。通过对4×4的LED芯片阵列结构进行有限元模拟,分析了温度对带有硅衬底的LED芯片阵列封装可靠性影响,同时对硅衬底进行分析和总结。     

大功率LED芯片直接固晶热电制冷器主动散热

发光二极管（LED）作为新一代绿色固态照明光源,已广泛应用于照明和显示等领域,但散热问题一直是大功率LED封装的关键技术瓶颈。采用大功率LED芯片直接固晶热电制冷器（TEC）的主动散热方法,可增强大功率LED的热耗散,提升大功率LED的发光性能和长期可靠性。利用高精度陶瓷基板和纳米银膏材料制备出高性能TEC,TEC冷端温度最低可达-22.2℃。将LED芯片直接固晶于TEC冷端的陶瓷基板焊盘上,实现LED芯片与TEC的集成封装,制备出LED-TEC主动散热模块。在芯片电流为1.0 A时,由于热电制冷的珀尔帖效应,LED-TEC模块可将LED芯片的工作温度从232℃降低到123℃（降温幅度为109℃）,且可使其输出光功率从1087m W提升到1 479 m W,光功率提升幅度达到36.1%。     

照明用大功率LED散热研究

大功率LED体积小、工作电流大,输入功率中大部分转化为热能,散热是需要解决的关键技术.文章介绍了大功率LED热设计的方法,针对大功率LED的封装结构,建立了热传导模型;对某照明用大功率LED阵列进行了散热设计,通过仿真分析和热评估试验验证了所采用的散热方法和设计的散热器满足LED阵列的散热要求.     

大功率LED封装的热管理

建立了一种大功率LED照明灯具的实际封装结构,采用ANSYS有限元软件对其进行热分析,得出了其稳态的温度场分布,并通过实际测量与计算得出了原始模型LED的实际节温,在此基础上提出了几种优化方案,分别采用不同的LED封装材料以及不同的铝热沉结构尺寸,并且进行了模拟对比,对其中一种可行性方案进行了参数优化,在经济和效果之间达到了较好的平衡,获得了较好的优化效果.     

大功率LED封装界面材料的热分析

基于简单的大功率LED器件的封装结构,利用ANSYS有限元分析软件进行了热分析,比较了四种不同界面材料LED封装结构的温度场分布。同时对纳米银焊膏低温烧结和Sn63Pb37连接时的热应力分布进行了对比,得出纳米银焊膏低温烧结粘接有着更好的热机械性能。     

改善大功率LED散热的关键问题

考虑热导率与散热方式的影响,使用大型有限元软件ANSYS10．0模拟并分析了大功率LED热分布。通过分析不同封装、热沉材料及散热方式对LED热分布与最大散热能力的影响,指出解决LED散热问题的关键不是寻找高热导率的材料,而是改变LED的散热结构或者散热方式。     

一种高功率白光LED灯具的封装热设计研究

建立了一种大功率白光LED照明灯具的封装结构,采用ANSYS有限元软件对其进行热分析,根据热分析的结果逐步改进封装结构,在考虑成本和尺寸限制的条件下,对LED的封装散热结构进行了优化.     

Thermal analysis of high power LED package with heat pipe heat sink

The goal of this study is to improve the thermal characteristics of high power LED (light-emitting diode) package using a flat heat pipe (FHP). The heat-release characteristics of high power LED package are analyzed and a novel flat heat pipe (FHP) cooling device for high power LED is developed. The thermal capabilities, including startup performance, temperature uniformity and thermal resistance of high power LED package with flat heat pipe heat sink have been investigated experimentally. The obtained results indicate that the junction temperature of LED is about 52 °C for the input power of 3 W, and correspondingly the total thermal resistance of LED system is 8.8 K/W. The impact of the different filling rates and inclination angles of the heat pipe to the heat transfer performance of the heat pipe should be evaluated before such a structure of heat pipe cooling system is used to cool high power LED system.     

Life-time estimation of high-power blue light-emitting diode chips

We have proposed a new concept of metal package by which we can estimate the lifetime of blue light-emitting diode (LED) chips with high accuracy. Components in conventional LED package which may obscure the degradation behavior of LED chip itself were removed or replaced by other materials or components. Three kinds of chips from different manufacturers were analyzed in this study using proposed metal packages. In this paper, the optical and electrical characteristics such as light-output degradation and reverse leakage current of high-power blue LED chip were investigated and analyzed. Also, the relationship between light-output degradation and electrical characteristics of LED chip was described. With aging time of 5000 h, only one kind of blue LED chip shows enough light-output degradation to estimate life-time.     

Thermal analysis of high power LED packages under the alternating current operation

In this paper we describe a novel thermal characterization method of GaN-based Light Emitting Diode (LED) package driven under the Alternating Current (AC) mode. The result was compared with the results from the thermal analysis for LED package operated under the Direct Current (DC) condition. Different from the DC condition, the junction temperature rise with the operation time of LED package was exhibited in a band formation. Finite Volume Method (FVM) was utilized to calculate the thermal performance of LED package under the AC condition using the input power extracted from the output current and voltage from the AC power supply. The experimental result was in a good agreement with the simulation data.     

A statistical study to identify the effects of packaging structures on lumen reliability of LEDs

The development of high-power light-emitting diode (LED) devices has been bedeviled by the reliability problems. And most reliability issues are caused by the packaging materials rather than the chips. However, which packaging material is the most influential remains unrevealed. To answer this question, a statistical method was introduced in this paper. Optical simulations were conducted to calculate the optical output power of LED package according to the orthogonal experimental design. Range and variance analyses were carried out to determine the significance of the relevant factors on the LED's light output. The results showed that the dome lens among the non-luminescent packaging materials had the most significance in affecting the light output. It is concluded that this method is useful in detecting the most significant part of LED packaging materials during the development of new packaging structures and is beneficial for enhancing the whole reliability of LED package effectively.     

基于倒装焊芯片的功率型LED热特性分析

对LED的导散热理论进行了研究,推导出了倒装焊LED芯片结温与封装材料热传导系数之间的关系。通过分析倒装焊LED的焊球材料、衬底粘结材料和芯片内部热沉材料对芯片结温的影响,表明衬底粘结材料对LED的结温影响最大,并且封装材料热传导系数的变化率与封装结构的传热厚度成反比,与传热面积成正比。该研究为倒装焊LED封装结构和材料的设计提供了理论支持。