플립칩의 경우 열전달 계수 정의/광특성 정의 첨부 파일 참고

the heat transfer coefficient (alpha) depends no on the material directly contacting the pads and the substrate, but on the WHOLE design outside of the respective surface. For instance, it does NOT really matter what material, Cu or Al, directly contacts the substrate in the scheme attached. What is really matter is what is the heat sink design below the PCB and how is this heat sink cooled - by free convection or by a fan, and so on...

SpeCLED considers a die alone, so the user needs to specify the heat transfer coefficient basing on his own experience, estimations, etc. If a user has measured or calculated the thermal resistance between the junction and the ambient, Rt (K/W), he can calculate the heat transfer coefficient as alpha = 1/(Rt*S), where S is the surface of the respective die area (substrate area for substrate-down mounting and total area of n- and p-pads for flip-chip mounting).

The default value of 1e5 refers to the case of thermal resistance between junction and ambient of 10 K/W and chip area of 1mm^2. The same alpha is in case of a heat slug of 1 mm thickness and heat conductivity of 100 W/m/K, and IDEAL cooling of the external heat slug surface. Please note that default heat transfer coefficient is introduced just indicate a typical order of magnitude. It should be corrected by the user according to the particular LED design