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 is a datasheet for the CITIZEN CLL130 Series Light Engine. It explains the thermal management requirements for the LED package, noting that an external radiator is necessary due to the small surface area of the package. The text describes how heat is conducted from the light-emitting diode through the package structure to an external heat sink.
The CLL130 is a light engine that uses an LED package to radiate light and heat.
Heat is conducted from the light-emitting diode through holes in the package to an external radiator like a heat sink.
The junction temperature is calculated using the formula Tj = (Rj-s + Rs-a) * Pd + Ta.