Ceramic circuit board and process for producing same

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 μm2 or less;
• and
• wherein the ceramic circuit board has both a high thermal cycle resistance and a high thermal shock resistance.

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 μm2 or less and no voids having an area greater than 200 μm2;
• and
• wherein the ceramic circuit board has both a high thermal cycle resistance and a high thermal shock resistance.