The light-emitting element of an LED 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 to the atmosphere. An external radiator such as heat sinks is thus required. The heat release configuration for the connection portion of the external radiator mainly uses heat conduction. Regarding LED packages, to control the junction temperature of the light-emitting element Tj is important. Tj must be kept from exceeding the absolute maximum rating in the specifications under any condition. Because direct measurement of the junction temperature of a light-emitting element inside a package is seldom possible, the temperature of a particular part on the package outer shell (the case temperature) Tc [deg C] is normally measured. Tj [deg C] is calculated from the thermal resistance between the junction and the case, Rj-c [deg C/W] and the amount of emitted heat, which is nearly equal to the input power Pd [W]. The package structure of the CL-L102 series minimizes the thermal resistance Rj-c, and the heat generated at the light-emitting element can be conducted to the external radiator efficiently.