The light-emitting diode of an LED package radiates light and heat according to the input power. However, the surface area of an LED package is quite small,and the package itself is expected to release little heat into the atmosphere.An external radiator such as a heat sink is thus required.The heat dissipation structure up to the connection portion of the external radiator uses mainly heat conduction.
This document describes the detailed heat dissipation structure of the CITIZEN CLLO20 Series light-emitting diode (LED) packages. It explains that an external radiator is required because the small surface area of the package cannot release sufficient heat into the atmosphere on its own.
The text details the thermal design process, focusing on minimizing the thermal resistance between the junction and the case (Rj-c). It provides formulas to calculate junction temperature based on input power and ambient conditions, along with charts correlating thermal resistance outside the package with driving current and ambient temperature.
The junction temperature must not exceed 150°C under any conditions.
The heat sink used in the simulation has outline dimensions of W 64mm x H 40mm.
The thickness of the heat conductive sheet is 0.12mm.