- 學位論文
應用氮化鋁基板於發光二極體模組之發光效率與熱傳性能之提升
The Improvement of Luminous Efficiency and Thermal Spreading Using Aluminum Nitride Ceramic Substrate of LED Module
摘要
現今單晶發光二極體技術成熟，產品多往多晶粒模組發展。多晶粒模組的優勢在於能提供更高的效率，但相對模組產生的熱能就越高，因此模組的散熱需求就更為嚴苛，模組主要的散熱方式為熱傳導與熱對流，藉由散熱基板將晶粒所產生的熱能傳導至散熱裝置，再利用散熱裝置與外界對流的方式將熱能排出。 散熱基板種類從玻璃纖維基板發展至金屬印刷電路板，兩種基板都存在著熱累積問題。玻璃纖維雖然為電絕緣，但其熱傳導係數約只有0.5 W/m•K。金屬印刷電路板的金屬材料通常為鋁，雖然鋁的熱傳導性值優異(~237 W/m•K)，但鋁基板需要絕緣層的電絕緣特性，阻絕電流藉由鋁基板垂直傳輸造成短路現象，而絕緣層熱傳導係數約莫為5 W/m•K。熱能經常在低熱傳導係數的材料上造成熱累積現象，為了解決多晶粒發光二極體模組所帶來高廢熱，陶瓷開始應用於散熱基板上。陶瓷基板主要為氧化鋁、氮化鋁兩種，其中以氮化鋁最佳，特點是電氣絕緣與高熱傳導率(~180 W/m•K)。 本研究應用氮化鋁於玻璃纖維基板上，在基板中嵌入一定比例的氮化鋁，讓晶粒產生的熱能主要由氮化鋁縱向的傳導至散熱裝置上。研究使用鋁基板為對照組，分別在兩散熱基板上安裝4顆發光二極體共32顆晶粒。實驗使用熱結構量測系統、積分球量測系統與紅外線熱影像即時溫度分析系統，分析兩種模組在不同環境溫度、驅動電流下的熱阻、光通量、表面溫度等特性的變化，最後利用有限元素分析法，最佳化氮化鋁佔玻璃纖維基板的長寬比例，以及探討玻璃纖維與氮化鋁接合處的熱累積現象。
並列摘要
The technology of single crystal LED is mature, most product development to multi-chip modules. Multi-chip modules have advantage of higher efficiency, but it also generate more heat energy. Therefore, the multi-chip module of heat management become more important. Heat conduction and heat convection is major heat dissipation of LED modules. The heat that is generated from junction, heat conduct to heatsink by substrate and dissipated into ambient air. The type of substrate have been development from FR4-PCB to MCPCB, both of them has thermal crowding problem. FR4 is insulation, but it’s thermal conductivity only 5 W/m•K. Al of MCPCB have high thermal conductivity(~237 W/m•K), but MCPCB need insulating layer to protect the short circuit from al top side to al bottom side. The thermal conductivity of insulating layer only 5 W/m•K.The thermal crowding often happen to low thermal conductivity material. To solve waste heat of multi-chip LED modules, the material of substrate begin using ceramic. AlN and Al2O3 is the major material of ceramic substrate. Among them the AlN is much better, because it’s insulation and high thermal conductivity(~180 W/m•K). In this study we use AlN on FR4 board call the AlN module. Exchange some parts of FR4 for AlN, let the heat from junction conduct to heatsink by AlN. Use the MCPCB module be a control group. Two modules was consist of 4 LED totally 32 chip. Analysis the thermal resistance、luminous flux and surface temperature in different ambent temperature and forward current by each measuring system. Finally optimization the AlN aspect ratio and discussion on thermal crowding between FR4 and AlN commissure.