Patent ID: 8894245

Claim:
A light-emitting device, comprising: a light emitting portion comprising a substrate comprising a mounting surface for mounting a light-emitting diode (LED) element and a metal portion formed on a surface of the substrate opposite to the mounting surface, the substrate comprising a ceramic or a semiconductor and the metal portion being bondable to a solder material; a heat dissipating member comprising one of aluminum, an aluminum alloy, magnesium and a magnesium alloy; and a circuit pattern formed on the heat dissipating member and electrically connected to the LED element of the light emitting portion by mounting the light emitting portion on the heat dissipating member, wherein a surface of the heat dissipating member includes a junction treated so as to be bondable to the solder material and a heat dissipating film formed in a periphery of the junction, wherein the metal portion of the light emitting portion is bonded to the junction of the heat dissipating member by the solder material, wherein no oxide film is formed on the junction of the heat dissipating member, wherein the solder material comprises a material that is impossible to be directly bonded to the heat dissipating member, wherein the heat dissipating member further comprises a plate-shaped main body, wherein the light emitting portion is mounted on an end surface of the main body of the heat dissipating member, and wherein a longitudinal length of the end surface in the metal portion of the light emitting portion is less than 200/X [mm] where X [10-6/° C.] is a difference between a rate of thermal expansion of the heat dissipating member and a rate of thermal expansion of the substrate of the light emitting portion.