Patent ID: 8168288

Claim:
A multilayer ceramic substrate comprising: a laminate including: a plurality of first ceramic layers each including a sintering ceramic material that includes a glass component or that is capable of generating a glass component and each being in a sintered state; and at least one second ceramic layer arranged between the first ceramic layers and that includes a first non-sintering ceramic material powder that is not substantially sintered at a temperature at which the sintering ceramic material is sintered, in which the first non-sintering ceramic material powder is in a fixed state due to a portion of the glass component being diffused from the first ceramic layers into the second ceramic layer; wherein the laminate further includes at least one underlayer that is disposed along at least one primary surface thereof facing outside of the laminate and that includes a second non-sintering ceramic material powder that is not substantially sintered at a temperature at which the sintering ceramic material is sintered, in which the second non-sintering ceramic material powder is in a fixed state due to a portion of the glass component being diffused from the first ceramic layers into the underlayer; at least one external conductive film is provided on the underlayer that includes conductive metal particles and a third non-sintering ceramic material powder that is not substantially sintered at a temperature at which the sintering ceramic material is sintered, in which the conductive metal particles and the third sintering ceramic material are in a fixed state due to a portion of the glass component being diffused from the first ceramic layers into the external conductive film; and when an area ratio on a cross-sectional surface parallel or substantially parallel to the primary surface of the laminate is observed, an area ratio of the conductive metal particles included in the external conductive film has a gradient that increases from the underlayer side to a surface side of the external conductive film, and an area ratio of the third non-sintering ceramic material powder included in the external conductive film has a gradient that increases from the surface side of the external conductive film to the underlayer side.