照明所消耗的電能佔總發電量重要的比例，LED只需花費很低的功率即可達到日常照明所需的亮度，故能有效的降低電能的使用。低功率的LED已廣泛應用於指示燈及顯示螢幕上，因其功率低，所以傳統LED並沒有太大的散熱問題。但若希望用來取代照明的高功率LED則受到其輸入功率高，使得散熱問題備受關注。而LED的效能和可靠度與熱場狀況密不可分，故有效的熱管理分析是必要的。 本研究利用有限元素套裝軟體，對高功率LED進行結構上的熱場模擬，並對模擬結果作深入的分析，進而針對溫度變化劇烈處提出有效的改善方法。發現溫度變化較大處為晶片上方的燈罩填充物及下方的焊錫空隙與晶片下表面處。本研究透過材料性質的提升與結構上的改變來討論對溫度變化較大處的影響，研究何種改進方法對LED的散熱有較好的表現，作為日後設計時參考的指標與努力的方向。 An important part of the generated electric power is used in lighting. The LEDs can use lower power to reach the same illumination in compared with general lighting equipments. Therefore, the LEDs could save more electric energy. Typical LEDs are used for indicator lights and display segments popularly, and they only produce low amounts of heat. However, the high power LEDs were used to substitute lighting equipments, which will induce some problems in heat dissipation. The efficiency and reliability of high power LEDs are related with heat, so the effective thermal management analysis is necessary. A finite element method package was used to simulate the thermal field of a high power LED in the present study, and then the simulated results were analyzed. Therefore, we proposed some improvements on epoxy and underfill which induced the apparent variation of temperature. We promoted material properties and changed the structure of chip package to study their effects for the thermal field of a high power LED. These results may give the directions for LED’s design.
