本研究使用熱超音波鍵合(Thermosonic bonding)技術，利用具高熱傳係數的金球(291W/m-K)將LED晶粒與子基板鍵合製作出覆晶式功率LED (Flip-Chip Power LED,FC PLED)，PLED通常面積大於1mm2，消耗功率大於1瓦以上，覆晶式LED可藉由高導熱性的金球與子基板結合，把產生的熱快速排出，以改善散熱問題，進而提昇發光效率。本研究設計的LED光罩圖形做出四種不同電極的LED，晶粒製程後利用I-V、積分球、熱像儀等不同分析方式來分析實驗結果，量測LED覆晶前後的散熱特性提升效果，再進一步同時鍍上反射層與不同金球數目，並且進行出光及光衰特性的量測。
結果發現覆晶式的LED在350mA電流下，其發光效率會比未覆晶的LED高22.7%，鍍上反射層的FCLED又會比沒鍍上反射層的FCLED高42.6%；其散熱特性經由熱像儀的量測可得知其金球數與散熱特性成正比，但是金球數達20~24顆時將會到達飽和，甚至以全面p金屬電極的覆晶LED(28~36顆)，金球數過多覆晶機的下壓力無法提供很好的鍵合，導致晶粒與子基板間無法有良好的接合，反而影響其電性與散熱特性。

In this research, using thermo-sonic bonding technology, the chip LED and the sub-mount are bonded to produce a flip-chip power LED with high thermal conductivity Au bumps (291W/mK). The PLED usually exhibits an area of larger than 1mm2 , its power consumption is greater than 1 watt, therefore the FC LED structure here we proposed can let the heat sink rapidly to improve the heat dissipation problem and enhance the luminous efficiency.
Four different LED electrode patterns are prepared for FC bonding, after the whole FC LED fabrication process are accomplished, IV & LI characteristics, integration sphere measurement and thermal image analysis etc., are adopted t to analyze their experimental results. The data showed that FC LEDs have the luminous efficiency 22.7% higher than non Flip-chip LED at 350mA, the flip-chip LED with reflector’s luminous efficiency is 42.6% higher than the flip-chip LED without reflector. Thermal characteristics show that the Au bump number is proportional to the thermal dissipation ability, but with a saturation at the Au bump reach the number of 20~24. Thus, even through the entire flip-chip LED with 28 ~ 36 Au bumps, due to the bonder can’t provide enough bonding force, result in a poor FC LED electrical and thermal characteristics.

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