Lighting device having light emitting element mounted in glass substrate

A lighting device comprising:

• a substrate having a front surface, a side surface and a rear surface, the front surface having a recess portion with a bottom surface;
• a lead frame embedded in the substrate and made of a material different from that of the substrate such that a thermal expansion coefficient difference between the substrate and the lead frame is equal to or smaller than 4×10−6/K, the lead frame having a portion exposed on the side surface of the substrate and a portion exposed on the bottom surface of the the recess portion, and a line width of a region of the portion of the lead frame exposed on the bottom surface of the recess portion of the substrate being narrower than a line width of a region of the portion of the lead frame exposed on the side surface of the substrate;
• a light emitting element mounted in the recess portion of the substrate and electrically connected with the portion of the lead frame exposed on the bottom surface of the recess portion;
• and
• a sealing material covering the light emitting element.

A lighting device comprising:

• a glass substrate having a front surface, a side surface and a rear surface, the front surface having a recess portion with a bottom surface, the glass substrate having a thermal expansion coefficient in the range of 8×10−6/K to 11×10−6/K;
• a metal lead frame embedded in the glass substrate and having a thermal expansion coefficient in the range of 4×10−6/K to 15×10−6/K, the metal lead frame having a portion exposed on the side surface of the glass substrate and a portion exposed on the bottom surface of the the recess portion, and a line width of a region of the portion of the metal lead frame exposed on the bottom surface of the recess portion of the glass substrate being narrower than a line width of a region of the portion of the metal lead frame exposed on the side surface of the glass substrate;
• an oxide film formed at a bonding interface between the metal lead frame and the glass substrate, the oxide film being formed of an oxide of the metal material forming the metal lead frame;
• a light emitting element mounted in the recess portion of the substrate and electrically connected with the portion of the lead frame exposed on the bottom surface of the recess portion;
• and
• a sealing material covering the light emitting element.