Packages base which allows mounting of a semiconductor element and electrode-wiring terminals on a mounting surface

1. A package base being made of a carbon composite material and having a mounting surface which includes:

a first area on which at least one first element including at least one semiconductor element is to be mounted; and

a second area on which at least one second element including at least a terminal for electrode wiring is to be mounted,

wherein said package base having the mounting surface has a unitary, monolithic, one-piece construction,

wherein said mounting surface of said package base has a step change in surface elevation between said first area and said second area,

wherein the first area includes an Au—Sn-based solder and the second area includes an Au—Ge-based solder, and

wherein the one semiconductor element is mounted on the first area through the Au—Sn-based solder and an insulator is bonded on the second area through the Au—Ge-based solder.

2. A package base according to claim 1 , wherein said carbon composite material is an isotropic carbon-fiber composite material.

3. A package base according to claim 1 , wherein said carbon composite material has a heat conductivity coefficient of 200 W/m·K or greater, and a thermal expansion coefficient of 4×10 −6 to 10×10 −6 /° C. in said first area in directions parallel to said mounting surface.

4. A package base according to claim 1 , wherein said step change in surface elevation is operative to align either of said at least one first element or said at least one second element.

5. A package base according to claim 1 , wherein said step change in surface elevation is characterized by said first area being located above said second area.

6. A package base according to claim 5 , wherein said step change is 0.1 mm or greater.

7. A package base according to claim 1 , wherein said step change in surface elevation is arranged so that said terminal is located above an upper surface of said at least one semiconductor element when said terminal and said at least one semiconductor element are mounted on said package base.

8. A package base according to claim 1 , said mounting surface of said package base further including a second step change operative to align with said first area, an optical element to be mounted.

9. A package base according to claim 8 , wherein said second step change is realized as a groove, shaped to receive at least an optical fiber as the optical element.

10. A semiconductor package comprising:

at least one first element including at least one semiconductor element;

at least one second element including at least a terminal for electrode wiring; and

a package base being made of a carbon composite material, having a unitary, monolithic, one-piece construction, and having a mounting surface which includes,

a first area on which said at least one first element is mounted, and

a second area on which said at least one second element is mounted,

wherein said mounting surface of said package base has a step change in surface elevation between said first area and said second area,

wherein said step change in surface elevation is arranged so that said first area is located above said second area, and

said terminal comprises,

an insulator being mounted on said second area and having a thickness greater than said step change, and

a conductive film formed on said insulator.

11. A semiconductor package according to claim 10 , wherein said carbon composite material is an isotropic carbon-fiber composite material.

12. A semiconductor package according to claim 10 , wherein said carbon composite material has a heat conductivity coefficient of 200 W/m·K or greater, and a thermal expansion coefficient of 4×10 −6 to 10×10 −6 /° C. in said first area in directions parallel to said mounting surface.

13. A semiconductor package according to claim 10 , wherein said step change in surface elevation aligns either of said at least one first element or said at least one second element.

14. A semiconductor package according to claim 10 , wherein said step change is 0.1 mm or greater.

15. A semiconductor package according to claim 10 , wherein said insulator is made of Al 2 O 3 , said conductive film is comprised of at least one layer, and an uppermost one of the at least one layer is made of gold.

16. A semiconductor package according to claim 10 , wherein said insulator is bonded onto said second area with Au—Ge-based or Au-Sn-based solder.

17. A semiconductor package according to claim 10 , wherein said at least one semiconductor element comprises a semiconductor light-emitting element, and said mounting surface of said package base further includes a second step change operative to align an optical element with said semiconductor light-emitting element.

18. A semiconductor package according to claim 17 , wherein said second step change is realized as a groove, shaped to receive at least an optical fiber as the optical element, wherein said groove is arranged to align an end face of the optical fiber with a lateral surface of the semiconductor light-emitting element, the lateral surface being lateral relative to a surface of said semiconductor light emitting element by which said semiconductor light emitting element is mounted to said first area, wherein said groove extends away from said lateral surface.

19. A semiconductor package comprising:

at least one first element including at least one semiconductor element;

at least one second element including at least a terminal for electrode wiring; and

a package base being made of a carbon composite material, having a unitary, monolithic, one-piece construction, and having a mounting surface which includes,

a first area on which said at least one first element is mounted, and

a second area on which said at least one second element is mounted,

wherein said mounting surface of said package base has a step change in surface elevation between said first area and said second area,

and said step change in surface elevation is arranged so that said terminal is located above an upper surface of said at least one semiconductor element, and said terminal comprises an insulation film being formed on said second area and a conductive film formed on said insulation film.