The semiconductor light emitting device, and a light source device and a lighting system using the same

The semiconductor light-emitting device of the present invention, on one side of the heat dissipating substrate 1 having an insulating property, and includes at least one conductor A2a, the conductor B2b, and a solid-state light-emitting element 3. Solid-state light-emitting element 3 is mounted on the wiring conductor A2a, on the wiring conductor B2b is not implemented by the solid-state light-emitting element 3. The solid-state light-emitting element 3, the entire lower surface of the facing surface of the main light extraction surface is mounted so as to be in close contact with the conductor A2a. When viewed mounting surface of the solid-state light-emitting element 3 from above, the conductor A2a is an element mounting area for mounting the entire lower surface of the solid-state light-emitting element 3, adjacent the periphery of said element mounting region, the element mounting area and a plurality of outflow adhesive trapping region provided without direction is biased against the surrounding. Conductor B2b is other than the outflow adhesive trapping region, the adjacent portion of the periphery of said element mounting area are arranged to be electrically isolated from the conductor A2a. Thus, it is possible to manufacture using orthodox practical techniques, as well as a possible high output and high-density mounting, it is possible to provide a possible semiconductor light emitting device conscious design at the time of lighting failure.