臺灣博碩士論文加值系統

由於地球暖化現象日趨嚴重，綠色科技產品在近幾年發展越來越快速，發光二極體即為眾多綠色科技產品之一。發光二極體具有高亮度、壽命長、省電及低污染等優點。在環保意識抬頭的今日，使用對環境汙染較小且消耗功率較低的發光二極體，取代傳統的白熾燈泡及日光燈勢必是未來的趨勢。然而，發光二極體的光電轉換效率仍然過低，大部份的輸入能量皆以熱能的形式輸出，造成晶片接面溫度上升，此現象將導致晶片發光強度降低、減少使用壽命。因此，對發光二極體進行有效的熱能管理將是發光二極體產業共同努力及研究的目標。
本研究根據熱傳導基本理論、半導體電性概念，使用有限單元分析軟體ANSYS®建立高功率發光二極體黏著於鋁製散熱鰭片之結構，搭配William與van de Pol等人提出自然熱對流理論帶入邊界條件進行模擬分析，並輔以順向偏壓法間接量測晶片接面溫度，驗證模擬結果的正確性，其結果顯示誤差皆在5%之內。此外，以此有限單元三維模型為基礎，進行新型發光二極體封裝結構(Chip-in-substrate type LED Package)的設計，模擬內部結構的熱傳物理行為及進行參數化分析。雖然新型發光二極體封裝結構在散熱效能上僅有微幅的進步，但可批量製造的特性，足以減少生產製造成本，增加此結構的競爭力。
在光衰壽命測試(Life Test)中，本研究使用不同幾何形狀、材質的散熱鰭片作為發光二極體散熱之用，以產生不同的晶片接面溫度，進行光衰壽命測試。將實驗結果繪製成相對發光強度與時間之關係曲線圖，探討晶片接面溫度和光衰形式的關係，並找出造成光衰的破壞機制，以改進現有發光二極體之問題。
在本研究中，以有限單元分析軟體ANSYS®模擬發光二極體之散熱特性，可快速的設計新型封裝結構並提出有效降低晶片接面溫度的方法，以提升發光二極體的發光強度與使用壽命，使發光二極體作為日常照明設備將指日可待。

誌謝 i
中文摘要 iii
英文摘要 v
表目錄 x
圖目錄 xii
第一章 序論 1
1-1 簡介 1
1-2 研究動機 2
1-3 文獻回顧 4
1-4 研究目標 10
第二章 基礎理論 13
2-1 發光二極體發光原理 13
2-2 光學特性基礎理論 22
2-2-1 光通量 23
2-2-2 色溫 24
2-2-3 演色性 25
2-3 熱傳遞分析理論 26
2-3-1 熱傳遞行為 26
2-3-2 發光二極體封裝元件之熱傳遞分析 29
2-4 有限單元法理論 34
2-4-1 穩態熱傳導有限單元法基礎理論 35
第三章 發光二極體封裝結構散熱分析 38
3-1 發光二極體接面溫度量測試驗 39
3-1-1 順向偏壓法量測過程介紹 40
3-1-2 發光二極體接面溫度量測結果 46
3-2 散熱鰭片溫度量測試驗 52
3-3 發光二極體光電轉換效率量測試驗 54
3-4 發光二極體之有限單元熱分析模型建立 56
3-4-1 有限單元之熱傳分析模型建立 56
3-4-2 熱分析模擬結果 62
3-4-3 熱分析模擬結果與實驗之驗證 65
3-5 導熱雙面膠之效應 68
3-6 不完美接合之效應 71
3-6-1 不完美接合之熱傳模型建立 71
3-6-2 不完美接合之模擬結果 73
3-6-3 不完美接合模擬結果之驗證 74
第四章 新型發光二極體封裝結構 77
4-1 新型發光二極體封裝結構 78
4-2有限單元熱分析模型建立 82
4-3熱分析模擬結果 86
4-4新型發光二極體封裝結構參數化分析 89
4-4-1 光電轉換效率之效應 90
4-4-2 填充材料之效應 92
4-4-3銅散熱塊之厚度效應 95
4-4-4銅散熱塊之面積效應 97
4-4-5散熱鰭片之效應 99
第五章 發光二極體之光衰壽命測試 102
5-1 光衰壽命測試實驗 102
5-2 不同散熱鰭片之效應 108
5-3 發光二極體壽命測試之結果 111
5-4 失效模式分析 113
第六章 結論與未來展望 118
參考文獻 122


表目錄
表2-1 各種幾何形狀下所相對應待定係數值 31
表3-1校準量測實驗結果(第1顆LED) 49
表3-2量測三次B值之平均結果(第1顆LED) 50
表3-3 接面溫度量測實驗結果(鋁製Heat Sink_1) 52
表3-4 積分球量測實驗結果 56
表3-5 發光二極體之內部結構實際幾何尺寸 57
表3-6 有限單元熱分析模型之材料參數 59
表3-7 實驗與模擬之驗證 68
表4-1 Chip-in-Substrate封裝結構之內部幾何尺寸 82
表4-2 有限單元熱分析模型之材料參數 83
表5-1量測三次B值之平均結果(第2顆LED) 103
表5-2量測三次B值之平均結果(第3顆LED) 104
表5-3量測三次B值之平均結果(第4顆LED) 104
表5-4量測三次B值之平均結果(第5顆LED) 104
表5-5量測三次B值之平均結果(第6顆LED) 104
表5-6 接面溫度量測實驗結果(鋁製Heat Sink_2) 105
表5-7 接面溫度量測實驗結果(Curamik散熱片_1) 106
表5-8 接面溫度量測實驗結果(Curamik散熱片_2) 106
表5-9 接面溫度量測實驗結果(無散熱鰭片_1) 107
表5-10 接面溫度量測實驗結果(無散熱鰭片_2) 107

圖目錄
圖1-1 發光二極體接面溫度與相對發光強度關係圖 3
圖2-1 P-N接面結構示意圖 13
圖2-2 原子聚集形成晶體內能帶結構示意圖 15
圖2-3 能帶與材料特性示意圖 16
圖2-4 簡化之半導體晶體(a)矽與(b)砷化鎵的能量動量圖 17
圖2-5 各種發光二極體發光層材料之發光波段區域圖 18
圖2-6 (a)形成接面前之P型與N型半導體能階圖 20
(b)熱平衡時，空乏區內的電場與P-N接面能階圖 20
圖2-7 同質結構發光二極體載子的漂移方向與複合示意圖。 21
圖2-8 雙異質結構發光二極體載子的漂移方向與複合示意圖。 21
圖2-9 多重量子井結構能階示意圖。 22
圖2-10 人眼敏感度曲線 24
圖2-11 黑體輻射強度與溫度分佈關係圖 25
圖2-12 不同幾何形狀特徵長度示意圖 32
圖2-13 散熱鰭片特徵長度示意圖 33
圖3-1 二極體電流電壓特性曲線圖 41
圖3-2二極體電流電壓溫度特性曲線圖 (T1 > T2) 41
圖3-3 (a)靜態模式輸入電流曲線圖(b)輸出電壓曲線圖 44
圖3-4 (a)動態模式輸入電流曲線圖(b)輸出電壓曲線圖 45
圖3-5 市售1W高功率白光發光二極體 46
圖3-6 多溫段控制烘箱 47
圖3-7 Keithley 2400 SouceMeter® 48
圖3-8 脈衝電流波形示意圖 48
圖3-9 校準量測實驗結果 49
圖3-10 鋁製銀色散熱鰭片 50
圖3-11 3M® Tape 8805導熱雙面膠 51
圖3-12 接面溫度量測實驗之輸出電壓波形 52
圖3-13 市售高功率發光二極體黏著於散熱鰭片 53
圖3-14 散熱鰭片溫度量測結果 54
圖3-15 SphereOptics之積分球量測儀器 55
圖3-16 發光二極體之幾何尺寸 58
圖3-17 鋁製銀色散熱鰭片之幾何尺寸 58
圖3-18 發光二極體黏著於鋁製散熱鰭片之1/4對稱模型 60
圖3-19 1/4對稱模型之邊界條件示意圖 61
圖3-20 等效熱對流係數設定示意圖 62
圖3-21 熱分析模擬結果 (單位：°C) 63
圖3-22 發光二極體之細部溫度梯度分佈 (單位：°C) 64
圖3-23 散熱鰭片之細部溫度梯度分佈 (單位：°C) 64
圖3-24 實驗與模擬之驗證 68
圖3-25 無雙面膠結構之模擬結果 (單位：°C) 70
圖3-26 導熱雙面膠之效應比較 71
圖3-27 不完美接合模型之設定 73
圖3-28 不完美接合模型之模擬結果 (單位：°C) 74
圖3-29 不完美接合模型之驗證 75
圖4-1 發光二極體封裝技術的演進 79
圖4-2 Chip-in-Substrate type LED Package之結構示意圖 80
圖4-3 加工後之第一層基板 81
圖4-4 Chip-in-Substrate封裝結構之實品圖 81
圖4-5 Chip-in-Substrate LED Package之幾何尺寸 83
圖4-6 Chip-in-Substrate LED Package之1/4對稱模型 84
圖4-7 Chip-in-Substrate LED Package之邊界條件示意圖 85
圖4-8 等效熱對流係數設定示意圖 86
圖4-9 Chip-in-Substrate LED Package熱分析結果 (單位：°C) 87
圖4-10發光二極體之細部溫度梯度分佈 (單位：°C) 88
圖4-11 散熱鰭片之細部溫度梯度分佈 (單位：°C) 88
圖4-12 新型與傳統發光二極體比較 90
圖4-13 海茲定律 91
圖4-14 光電轉換效率之效應 92
圖4-15 填充材料之效應 94
圖4-16 6W時，填充材料效應之溫度梯度比較 95
圖4-17 銅散熱塊之厚度效應 96
圖4-18 銅散熱塊之面積效應 98
圖4-19 散熱鰭片之大小變化 100
圖4-20散熱鰭片之效應 100
圖5-1 Curamik生產之散熱片 103
圖5-2 不同材質、幾何形狀之散熱鰭片 110
圖5-3 實驗樣品之初始發光強度值 112
圖5-4 時間與相對發光強度之關係曲線圖 113
圖5-5 晶片接面溫度約85°C時，發光二極體之光譜圖 114
圖5-6晶片接面溫度約100°C時，發光二極體之光譜圖 115
圖5-7晶片接面溫度約120°C時，發光二極體之光譜圖 115

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