Patent ID: 7781066

Claim:
A multilayer ceramic substrate comprising: a base layer made of an aggregate of a first powder including a glass material and a first ceramic material; a constraining layer made of an aggregate of a second powder including a second ceramic material that is not sintered at a temperature at which the glass material melts; an intermediate layer made of an aggregate of a third powder including a viscosity-reducing material that reduces the viscosity of the melt of the glass material; and a conductive film disposed along at least one main surface of the base layer, the constraining layer, and the intermediate layer; wherein the intermediate layer is arranged such that one main surface thereof is in contact with the base layer and the other main surface thereof is in contact with the constraining layer; the intermediate layer has a thickness of about 2 μm to about 10 μm; at least a portion of the first powder is in a sintered state; and the second powder is in an unsintered state, and particles of the second powder are bonded to each other by diffusion or flow of a portion of the first powder including the glass material and a portion of the third powder into the constraining layer.