Patent ID: 8435640

Claim:
A metal-ceramic substrate comprising a multi-layer, plate-shaped ceramic material base layer and at least one copper or copper alloy metallization applied on a surface side of the ceramic material base layer with an oxidic ceramic intermediate layer between the ceramic material base layer and the at least one copper or copper alloy metallization, said at least one copper or copper alloy metallization being bonded to the ceramic material base layer by means of direct bonding (DCB) or an active soldering process, wherein the ceramic material base layer is coated on at least one surface with an oxidic ceramic material forming the oxidic ceramic intermediate layer and the oxidic ceramic material is melted on or dense sintered at a temperature between 1200° C. and 1680° C., the ceramic material base layer comprising at least one base layer of a silicon nitride ceramic, wherein the oxidic ceramic intermediate layer has a thermal expansion coefficient not greater than 6×10 −6 ° K −1 , wherein a free silicon oxide content in the oxidic ceramic intermediate layer is approximately zero at least in an area of a bond between the oxidic ceramic intermediate layer and the at least one copper or copper alloy metallization, and wherein the free silicon oxide content in the oxidic ceramic intermediate layer increases in relation to an oxidic ceramic content from the area of the bond between the oxidic ceramic intermediate layer and the at least one copper or copper alloy metallization toward a surface side of the ceramic material base layer.