PHILIPS(飞利浦)_LED光源散热设计指南.ppt

邹静 （）,gbu led lamps and systems,june 2010,general guide to the heatsink design for fortimo modules,2,nice to know:,/lexel /fortimo 网上有: product leaflet; design-in guide; optical files; catalog; photometric files certificates 3d file such as cad file,3,led 模组会因为没有接散热器，过度受热而坏掉吗？,4,led 模组会因为没有接散热器，过度受热而坏掉吗？,不会, 我们的模组有高温保护功能，一旦模组温度升到一定值，驱动器的输出电流会自动减小，这会阻止模组温度继续升高。,led performance issue? tj必须保持在特定的温度下，以免颜色飘移， 或者光通的改变。,5,why bother?,led performance issue? tj必须保持在特定的温度下，以免颜色飘移， 或者光通的改变。 lifetime concern? 焊点经历一定次数冷热循环后（热胀冷缩的循环）会产生脱节。一般来说，焊点的温度越高，脱节前经历的冷热循环数越低。,6,why bother?,tc 对于模组来讲,只要 tc保持在 650c or 550c, lifetime（b50l70）会在 50000个小时左右。llm模组由于具有clo，所以lifetime不使用l70。,7,tc and lifetime,8,special features fortimo led linear,9,多少的功率（百分比）变成了热?,10,how much power is turned into heat?,一般来说, 有 remote phosphor 的模组, 比如： 2/3 的模组消耗的功率（系统功率 驱动器的功率）转变成了热。,11,how much power is turned into heat?,一般来说, 有 remote phosphor 的模组, 比如： 2/3 的模组消耗的功率（系统功率 驱动器的功率）转变成了热。,1-45% = 55% 的功率转换成热!,1-26% = 74% 的功率转换成热!,转换成光的效率,12,how much power is turned into heat?,一般来说, 有 remote phosphor 的模组, 比如： 2/3 的模组消耗的功率（系统功率 驱动器的功率）转变成了热。,side story!,13,how to get rid of heat?,被动散热,主动散热,thermal management: heat spreading （传热）: 把热传到一个更大的面积 heat sinking （散热）: 通过convection（热对流）和radiation（ 热辐射）使热传到空气环境中。,14,thermal management heat spreading,主要的传热机制（从模组到散热器）是conduction（导热）; 为了增加模组和散热器之间的热传导，一般要使用thermal interface materials (导热介质), 比如导热胶，或者导热膜，甚至导热管. 散热器要用thermally conducting material（导热材料） 金属是比较好的导热材料 很多情况下铝是首选，因为造工比较方便，价格也比较合适。,15,thermal management heat sinking (convection),影响热对流的因素如下: 热对流系数 pconv = hc* aeff* (tc-tamb), 有效面积 热阻(rth)如下: rth= t/pheat = 1/ (h* aeff* ),热功率,tcase,环境温度,16,主动散热和被动散热的比较：,17,thermal management heat sinking (radiation),热辐射的影响因素也可以写成如下： prad = hr *aeff* (tc-tamb), 热辐射系数 热辐射因素和emission coefficient(放热系数)成正比，而emission coefficient 和 表面处理有关：,18,thermal management heat sinking (radiation),整个散热（热对流 + 热辐射）： pheat = h * aeff* (tc-tamb), 在我们模组的工作范围内，一般来说，热辐射在整个散热中占到 20% - 40% 左右，整个的传热系数在2-10之间。,19,heatsink examples,passive,passive,passive,passive,active,active,20,要考虑的因素：,用导热性能好的材料 铝是较好的选择 散热器的整个有效面积 aeff = 1/ (h*rth) 散热片的摆放位置 散热片之间的距离 散热片的长度 散热片的厚度 用放热系数较大的表面处理 铝一般用喷漆或者阳极 为了保证模组和散热器之间的热传导，要用导热介质,21,heatsink verification: measuring tc (with heatsink attached),the stabilization time for tc can be between half an hour up to 3 hours, which depends on the measurement environment. in general, it takes longer to stabilize in an enclosed environment, such as a simulated ceiling environment. thermal couple can be used to measure tc. ensure good contact between the thermal couple and the module by taping (aluminum tape) or applying a thin layer of quick drying glue and string relief thermal couple has certain dimensions, so it is not recommended to put them between a module and a heat sink directly unless there is already a groove made on the heatsink. however, tc can also be measured towards the side of the module, which of course will be a few degrees less than the temperature in the center.,22,样例: 模拟的天花板环境中tc的测量,tc等了1-2小时候才稳定； 一般来讲，在一个封闭的环境中， tc要等比较长的时间才可以稳定下来,23,样例: tc 在敞开环境中的测量,尽量避开空气流动比较大的地方！,+ 100c,56.80c,t_ambient,24,25,dlm: 在u型的边上测,如果散热器安装在dlm的底部，边上的温 度应该610c，只要可以基本保证tc650c,simulation made with heatsink attached to the sides.,26,散热器设计的流程,收集基本的一些信息，比如多少的热功率，以及设计上的一些形状或者 大小的限制等等； 把以上信息输入到热学软件中,进行计算机模拟; 初步判断模拟结果对散热器设计进行修正; eg. mould the first heatsink and do extensive real temperature testing.,measurement results,240mmx60mmx30mm,what is h?,28,what is h?,a = 0.24x 0.03 x 9 x 2 = 0.13m2,t = 52-25.6 = 26.40c p_heat = 16w p_heat = h * a * t so h = 16/(0.13 * 26.4) = 4.6 w/m2 0c,现在我们知道了h,下一步就要回到红色标示的公式去计算所需要的 面积! 改进已有的散热器,再进行测量,直到达到需要的tc.,29,heatsink vendors,below are a few links to professional heatsink providers: for passive cooling: avc: .tw/ for active cooling: nuventix: /led_cooling/ emb papst: /de/ sunon: /index.