Abstract: A method of producing a composite sheet in which a through hole formed in a predetermined portion of the first ceramic sheet is buried with a different kind of sheet having substantially the same thickness as the first ceramic sheet, such as a resin sheet a metal sheet or a ceramic sheet of a material different from that of the first ceramic sheet. A first method comprises a step of preparing a first ceramic sheet from a ceramic powder, and a different kind of sheet; a step of forming a through hole in a predetermined portion of the first ceramic sheet; a step of laminating the different kind of sheet on the ceramic sheet in which the through hole is formed; and a step of preparing a composite sheet by pressing the portion of the first ceramic sheet where the through hole is formed from the side of the different kind of sheet, such that the first ceramic sheet and the different kind of sheet are integrated together.

Abstract: A composite ceramic board comprising an insulating board of insulating layers of alumina ceramics and dielectric layers of ceramics having a dielectric constant smaller than that of said insulating layers which are fired as a unitary structure, and metallized wirings of a low-resistance conductor such as of Au, Ag, Cu or Pl formed on the surfaces and inside thereof, and a method of producing the same. The composite ceramic board not only has a large strength and a high thermal conductivity but also exhibits excellent high-frequency characteristics and is suited for use as a high-frequency wiring board. The invention further provides an optical/electronic-mounted circuit substrate using the above board, and a mounted board having the circuit substrate of the invention connected to an electronic circuit formed on a mother board.

Abstract: A method of producing a composite sheet in which a through hole formed in a predetermined portion of the first ceramic sheet is buried with a different kind of sheet having substantially the same thickness as the first ceramic sheet, such as a resin sheet a metal sheet or a ceramic sheet of a material different from that of the first ceramic sheet. A first method comprises a step of preparing a first ceramic sheet from a ceramic powder, and a different kind of sheet; a step of forming a through hole in a predetermined portion of the first ceramic sheet; a step of laminating the different kind of sheet on the ceramic sheet in which the through hole is formed; and a step of preparing a composite sheet by pressing the portion of the first ceramic sheet where the through hole is formed from the side of the different kind of sheet, such that the first ceramic sheet and the different kind of sheet are integrated together.

Abstract: A composite ceramic board comprising an insulating board of insulating layers of alumina ceramics and dielectric layers of ceramics having a dielectric constant smaller than at of said insulating layers which are fired as a unitary structure, and metallized wirings of a low-resistance conductor such as of Au, Ag, Cu or Pt formed on the surfaces and inside thereof, and a method of producing the same. The composite ceramic board not only has a large strength and a high thermal conductivity but also exhibits excellent high-frequency chararteristics and is suited for use as a high-frequency wiring board. The invention further provides an optical/electronic-mounted circuit substrate using the above board, and a mounted board having the circuit substrate of the invention connected to an electronic circuit formed on a mother board.

Abstract: A wiring board having an insulating substrate of aluminum oxide ceramics and a surface wiring layer formed on the surface of said insulating substrate, wherein the aluminum oxide ceramics constituting said insulating substrate contains a manganese compound in an amount of from 2.0 to 10.0% by weight in terms of MnO2, and has a relative density of not smaller than 95%, and said surface wiring layer contains copper in an amount of from 10 to 70% by volume and at least one high-melting metal selected from the group consisting of tungsten and molybdenum in an amount of from 30 to 90% by volume, and further contains copper as a matrix, said copper matrix having a diffusion structure in which are diffused the particles of said high-melting metal having an average particle diameter of from 1 to 10 &mgr;m.

Abstract: A glass-ceramic sintered body comprising an SiO.sub.2 --Al.sub.2 O.sub.3 --MgO--ZnO--B.sub.2 O.sub.3 type crystalline glass and alumina, said sintered body containing at least 10% by weight of a spinel crystalline phase; and a substrate composed of the sintered material. There is also provided a process for producing the glass-ceramic sintered body which comprises adding a binder to a mixed powder of an SiO.sub.2 --Al.sub.2 O.sub.3 --MgO--ZnO--B.sub.2 O.sub.3 type crystalline glass and alumina, molding the mixture into a predetermined shape, and firing the mixture into a predetermined shape, and firing the molded mixture at a temperature of 925.degree. to 1000.degree. C. in a non-oxidizable atmosphere. The glass-ceramic sintered body and the substrate composed of it in accordance with the present invention have excellent mechanical strength and thereby have markedly increased metallizing adhesion strength.