Ceramic circuit board and process for producing same

1. A ceramic circuit board, comprising:

a ceramic substrate;

a copper circuit plate bonded to at least one surface of the ceramic substrate through a brazing material layer comprising Ag, Cu, and Ti; and

a brazing material protrudent part formed by the brazing material layer which protrudes outside from a side surface of the copper circuit plate;

wherein the brazing material protrudent part comprises a Ti phase and a TiN phase of 3% by mass or more in total, which is different from the total amount of a Ti phase and a TiN phase in the brazing material layer that is interposed between the ceramic substrate and the copper circuit plate, and a number of voids each having an area of 200 μm 2 or less in the brazing material protrudent part is one or less (including zero).

2. The ceramic circuit board according to claim 1 , wherein the brazing material protrudent part comprises the Ti phase and TiN phase of from 3% by mass to 40% by mass in total.

3. The ceramic circuit board according to claim 1 , wherein the brazing material protrudent part has a protrudent length that is 0.01 mm or more.

4. The ceramic circuit board according to claim 1 , wherein the ceramic substrate is composed of silicon nitride, aluminum nitride, or alumina, and the copper circuit plate has a thickness of 0.25 mm or more.

5. The ceramic circuit board according to claim 1 , wherein the brazing material layer is formed using a brazing material having a composition consisting of Ag: 90 to 50% by weight, Sn and/or In: 5 to 15% by weight, Ti: 0.1 to 6% by weight, and a remnant Cu and unavoidable impurities.

6. A ceramic circuit board, comprising:

a ceramic substrate;

a copper circuit plate;

a brazing material layer including Ag, Cu, and Ti disposed between the ceramic substrate and the copper circuit plate to bond the copper circuit plate to the ceramic substrate; and

a brazing material protrudent part formed by the brazing material layer that protrudes out from between the ceramic substrate and the copper circuit plate, and from outside of a side surface of the copper circuit plate;

wherein the brazing material protrudent part has a Ti phase and a TiN phase of 3% by mass or more in total, which is different from a total amount of a Ti phase and a TiN phase in the brazing material layer interposed between the ceramic substrate and the copper circuit plate;

wherein the brazing material protrudent part includes no more than one void having an area of 200 μm 2 or less; and

wherein the ceramic circuit board has both a high thermal cycle resistance and a high thermal shock resistance.

7. The ceramic circuit board of claim 6 , wherein the brazing material protrudent part is subject to only a single etchant.

8. The ceramic circuit board of claim 7 , wherein the brazing material protrudent part is etched with a copper plate etchant.

9. The ceramic circuit board of claim 6 , wherein the brazing material protrudent part is etched with a copper plate etchant.

10. The ceramic circuit board of claim 6 , wherein the brazing material protrudent part is etched with a copper plate etchant including ferric chloride or cupric chloride.

11. The ceramic circuit board of claim 6 , wherein the brazing material protrudent part is etched with a copper plate etchant including ferric chloride or cupric chloride of no greater than 15 wt %.

12. The ceramic circuit board of claim 6 , wherein the brazing material is not subject to a brazing material etchant.

13. The ceramic circuit board of claim 6 , wherein the brazing material protrudent part is without voids having an area of greater than 200 μm 2 .

14. The ceramic circuit board of claim 6 , wherein the brazing material protrudent part includes a plurality of pores etched therein with a copper plate etchant.

15. A ceramic circuit board, comprising:

a ceramic substrate;

a copper circuit plate;

a brazing material layer including Ag, Cu, and Ti disposed between the ceramic substrate and the copper circuit plate to bond the copper circuit plate to the ceramic substrate; and

a brazing material protrudent part of the brazing material layer that protrudes out from between the ceramic substrate and the copper circuit plate, and from outside of a side surface of the copper circuit plate;

wherein the brazing material protrudent part has a Ti phase and a TiN phase of 3% by mass or more in total, which is different from a total amount of a Ti phase and a TiN phase in the brazing material layer interposed between the ceramic substrate and the copper circuit plate;

wherein the brazing material protrudent part is etched with a copper plate etchant including 15 wt % of ferric chloride or cupric chloride such that the brazing material protrudent part includes no more than one void having an area of 200 μm 2 or less and no voids having an area greater than 200 μm 2 ; and

wherein the ceramic circuit board has both a high thermal cycle resistance and a high thermal shock resistance.

16. The ceramic circuit board of claim 15 , wherein the brazing material protrudent part is subject to only a single etchant.

17. The ceramic circuit board of claim 15 , wherein the brazing material is not subject to a brazing material etchant.

18. The ceramic circuit board of claim 15 , wherein the brazing material protrudent part includes a plurality of pores etched therein with the copper plate etchant.

19. The ceramic circuit board of claim 15 , wherein the brazing material protrudent part includes the Ti phase and the TiN phase from 3% by mass to 40% by mass in total.

20. The ceramic circuit board of claim 15 , wherein the brazing material protrudent part has a protrudent length that is 0.01 mm or more and is 30% or less of a space in the copper circuit plate.