Ceramic substrate for mounting a device, ceramic substrate for mounting an LED, LED lamp, headlight and electronic parts

1. A ceramic substrate for mounting an LED, the ceramic substrate comprising a through-hole for screw-fastening and a recessed portion for screw-fastening or position registration and which is provided on at least one edge surface of a circumference thereof, and

wherein the ceramic substrate is a silicon nitride substrate having a plate thickness of 0.2 mm to 1 mm, a heat conductivity of 60 W/m·K or more and a 3 point bending strength of 600 MPa or more at ambient temperature,

wherein the through-hole has a diameter of 1 mm to 5 mm, and a minimum distance from the through-hole to one edge of the ceramic substrate is 1 mm or more, and

wherein a ratio of broken ceramic substrate is 5% or less when a screw fastening torque of 25 N·m is applied to the ceramic substrate.

2. The ceramic substrate according to claim 1 , the substrate further comprising a circuit section.

3. The ceramic substrate according to claim 1 , the substrate having a length of one edge of 10 mm to 200 mm.

4. The ceramic substrate according to claim 1 , wherein the recessed portion has a width of 1 mm to 5 mm and a depth of 1 mm to 5 mm.

5. The ceramic substrate according to claim 1 , wherein a minimum distance from the recessed portion to one edge of the substrate is 1 mm or more.

6. An LED lamp comprising the ceramic substrate as claimed in claim 1 and a light-emitting diode mounted on the ceramic substrate.

7. The LED lamp according to claim 6 , the LED lamp comprising two or more of the light-emitting diodes.

8. The LED lamp according to claim 6 , the lamp being used for a vehicle.

9. The LED lamp according to claim 6 , the lamp being used for a headlight.

10. A headlight comprising the LED lamp as claimed in claim 6 .

11. The headlight according to claim 10 , the headlight comprising:

a substrate to which the LED lamp is secured; and

a cover with a lens function which is secured to the substrate and cover the LED lamp,

wherein the LED lamp is secured to the substrate by screw-fastening the through-hole and recessed portion of the ceramic substrate onto the substrate.

12. An electronic part comprising:

a ceramic substrate having two elongated edges opposite to each other;

one of the edges having a recess therein, the recess being defined by walls of the substrate while leaving an outer portion of the recess open;

the other edge having a through hole adjacent to it;

at least one device mounted on a major surface of the ceramic substrate, the device being selected from the group of light emitting diodes, semiconductor devices and solar cells;

a housing member;

a first screw located in the recess for fastening the ceramic substrate to the housing member;

a second screw located in the through hole for fastening the ceramic substrate to the housing member;

wherein the ceramic substrate is a silicon nitride substrate having a plate thickness of 0.2 mm to 1 mm, a heat conductivity of 60 W/m·K or more and a 3-point bending strength of 600 MPa or more at ambient temperature,

wherein the through-hole has a diameter of 1 mm to 5 mm, and a minimum distance from the through-hole to one edge of the ceramic substrate is 1 mm or more, and

wherein a ratio of broken ceramic substrate is 5% or less when a screw fastening torque of 25 N·m a applied to the ceramic substrate.