A ceramic structural body includes a substrate that is composed of a ceramic(s), a hole that is opened on a surface of the substrate, and a seal material that is positioned at an opening portion of the hole.

A method for producing a metal-ceramic substrate includes attaching a metal layer to a surface side of a ceramic layer, the metal layer being structured into a plurality of metallization regions respectively separated from one another by at least one trench-shaped intermediate space to form conductive paths and/or connective surfaces and/or contact surfaces. The method further includes filling the at least one trench-shaped intermediate space with an electrically insulating filler material, and covering first edges of the metallization regions facing and adjoining the surface side of the ceramic layer in the at least one trench-shaped intermediate space, as well as at least one second edge of the metallization regions facing away from the surface side of the ceramic layer in the at least one trench-shaped intermediate space, by the electrically insulating filler material.

The present invention provides a silicon nitride circuit board in which metal plates are attached on front and rear sides of a silicon nitride substrate having a three-point bending strength of 500 MPa or higher, with attachment layers interposed therebetween, wherein assuming that a thickness of the metal plate on the front side is denoted by t1, and a thickness of the metal plate on the rear side is denoted by t2, at least one of the thicknesses t1 and t2 is 0.6 mm or larger, a numerical relation: 0.10|t1t2|0.30 mm is satisfied, and warp amounts of the silicon nitride substrate in a long-side direction and a short-side direction both fall within a range from 0.01 to 1.0 mm. Due to above configuration, TCT properties of the silicon nitride circuit board can be improved even if the thicknesses of the front and rear metal plates are large.

A method of forming an improved sealed joint between two or more shaped ceramic structures includes providing at least first and second ceramic structures joined together by a joint comprising one or more of silicon, a silicon alloy and a silicon compound, the joint including an exposed portion interior of the joined structures, then converting at least a portion of the one or more of silicon, a silicon alloy, and a silicon compound of the joint to silicon nitride and/or silicon carbide, desirably at least at an interior exposed portion of the joint, so as to provide increased chemical resistance for the joint when aggressive chemicals are used within device formed from the sealed-together ceramic structures. The ceramic structures desirably comprise silicon carbide.