Patent ID: 9686872
Date: 2017-06-20
CPC Classifications: H05K

Claim:
1. A ceramic multilayer substrate formed by stacking and firing a plurality of insulating layers made of ceramic materials, wherein: the insulating layer in an uppermost surface layer includes a first ceramic layer, a second ceramic layer directly stacked on the first ceramic layer and configured to suppress contraction, and a surface-layer via conductor penetrating through the first and second ceramic layers and having a tapered shape gradually tapering toward a lower layer side, the surface-layer via conductor having an end surface that is exposed from the second ceramic layer and that is directly connected to a terminal of a component mounted to a surface of the second ceramic layer, and at least the second ceramic layer contains a material suppressing thermal contraction of the surface-layer via conductor or deforming in compliance with the thermal contraction of the surface-layer via conductor, wherein a weight ratio of alumina contained in the second ceramic layer is higher than a weight ratio of alumina contained in the first ceramic layer; wherein the surface-layer via conductor is a continuous body that includes a portion formed in the first ceramic layer and a portion formed in the second ceramic layer, and that has two tapered shapes defined by the two portions at different spreading slope angles, and a spreading slope angle of the tapered shape on the second ceramic layer side is larger than a spreading slope angle of the tapered shape on the first ceramic layer side.