A method of joining a metal-ceramic substrate having metalization on at least one side to a metal body by using a metal alloy is disclosed. The metal body has a thickness of less than 1.0 mm, and the metal alloy contains aluminum and has a liquidus temperature of greater than 450° C. The resulting metal-ceramic module provides a strong bond between the metal body and the ceramic substrate. The resulting module is useful as a circuit carrier in electronic appliances, with the metal body preferably functioning as a cooling body.

The present invention provides a high thermal conductive silicon nitride sintered body having a thermal conductivity of 50 W/m.Math.K or more and a three-point bending strength of 600 MPa or more, wherein when an arbitrary cross section of the silicon nitride sintered body is subjected to XRD analysis and highest peak intensities detected at diffraction angles of 29.3±0.2°, 29.7±0.2°, 27.0±0.2°, and 36.1±0.2° are expressed as I.sub.29.3°, I.sub.29.7°, I.sub.27.0°, and I.sub.36.1°, a peak ratio (I.sub.29.3°)/(I.sub.27.0°+I.sub.36.1°) satisfies a range of 0.01 to 0.08, and a peak ratio (I.sub.29.7°)/(I.sub.27.0°+I.sub.36.1°) satisfies a range of 0.02 to 0.16. Due to above configuration, there can be provided a silicon nitride sintered body having a high thermal conductivity of 50 W/m.Math.K or more, and excellence in insulating properties and strength.

A circuit board includes a metal circuit plate, a metallic heat diffusing plate disposed below the metal circuit plate and having an upper surface and a lower surface, a metallic heat dissipating plate below the heat diffusing plate, an insulating substrate disposed between the metal circuit plate and the heat diffusing plate, and an insulating substrate disposed between the heat diffusing plate and the heat dissipating plate. A grain diameter of metal grains contained in the heat diffusing plate decreases from each of the upper surface and the lower surface of the heat diffusing plate toward a center portion of the heat diffusing plate in a thickness direction.

To improve a TCT characteristic of a circuit substrate. The circuit substrate comprises a ceramic substrate including a first and second surfaces, and first and second metal plates respectively bonded to the first and second surfaces via first and second bonding layers. A three-point bending strength of the ceramic substrate is 500 MPa or more. At least one of L1/H1 of a first protruding portion of the first bonding layer and L2/H2 of a second protruding portion of the second bonding layer is 0.5 or more and 3.0 or less. At least one of an average value of first Vickers hardnesses of 10 places of the first protruding portion and an average value of second Vickers hardnesses of 10 places of the second protruding portion is 250 or less.

A milling device is rotatable in one direction around a longitudinal center axis defining a forward direction and an opposite rearward direction, and includes a front part and a rear part. The front part has cutting edges, each having a longitudinal extension, and chip flutes, each having a longitudinal extension. The front part is made of a monolithic piece of ceramic. The rear part is configured to be fixed in a rotatable tool body or a rotatable chuck. The rear part is also made of a monolithic piece of cemented carbide. A front end surface of the rear part has a smaller area than a rear end surface of the front part. The front end surface of the rear part and a rear end surface of the front part are permanently bonded or brazed to each other by a joint.

A carrier substrate (1) for electrical components, in particular metal-ceramic substrate (1) for electrical components, comprising an insulation layer (10), the insulation layer (10) preferably having a material comprising a ceramic or a composite comprising at least one ceramic layer, a component metallization (20) which is formed on a component side (BS) and has a first primary structuring (21), and a cooling part metallization (30) which is formed on a cooling side (KS) opposite the component side (BS) and has a second primary structuring (31), wherein the insulation layer (10), the component metallization (20) and the cooling part metallization (30) are arranged one above the other along a stacking direction (S), and
wherein the first primary structuring (21) and the second primary structuring (31), as viewed in the stacking direction (S), run congruently at least in portions.

A wiring board includes an insulating substrate and a wiring conductor. The insulating substrate includes a first layer having an upper surface and a lower surface and having a first content of aluminum oxide and containing mullite and a second layer stacked on the upper surface and/or the lower surface of the first layer and having a second content of aluminum oxide greater than the first content. The wiring conductor is located inside the first layer and contains a manganese compound and/or a molybdenum compound. A manganese silicate phase and/or a magnesium silicate phase in an interface area between the insulating substrate and the wiring conductor.

The present invention provides a power module substrate including an insulating substrate, a circuit layer which is formed on one surface of the insulating substrate, and a metal layer which is formed on the other surface of the insulating substrate, in which the circuit layer has a first aluminum layer made of aluminum or an aluminum alloy which is bonded to the insulating substrate and a first copper layer made of copper or a copper alloy which is bonded to the first aluminum layer by solid-phase diffusion, the metal layer has a second aluminum layer made of aluminum or an aluminum alloy, and a relationship between a thickness t.sub.1 of the circuit layer and a thickness t.sub.2 of the second aluminum layer of the metal layer satisfy t.sub.1<t.sub.2.

A method of joining a metal-ceramic substrate having metallization on at least one side to a metal body by using metal alloy is disclosed. The metal body has a thickness of less than 1.0 mm and the metal alloy contains aluminum and has a liquidus temperature of greater than 450° C. The resulting metal-ceramic module provides a strong bond between the metal body and the ceramic substrate. The resulting module is useful as a circuit carrier in electronic appliances, with the metal body preferably functioning as a cooling body.

A power module substrate 10 is provided with: an insulating substrate 1; and a metal sheet 2 that is joined to the insulating substrate 1 via a brazing material 3, wherein regarding the surface roughness, in the thickness direction, of the lateral surface of the metal sheet 2, the surface roughness of a corner 2a farthest from the center of the metal sheet 2 is larger than the surface roughness of plane parts 2b, which bound the corner, in at least a plan view. Also provided is a power module 100 which is formed by mounting an electronic component 40 on this power module substrate 10.