A sintered body includes a crystal grain containing silicon nitride, and a grain boundary phase. If dielectric losses of the sintered body are measured while applying an alternating voltage to the sintered body and continuously changing a frequency of the alternating voltage from 50 Hz to 1 MHz, an average value ε.sub.A of dielectric losses of the sintered body in a frequency band from 800 kHz to 1 MHz and an average value ε.sub.B of dielectric losses of the sintered body in a frequency band from 100 Hz to 200 Hz satisfy an expression |ε.sub.A−ε.sub.B|≤0.1.

When a laminate of a plurality of different materials including a metal plate is bonded in a pressurized and heated state, a first pressurizing member in which a first metal foil/a carbon sheet or a ceramic sheet/a graphite sheet are laminated in this order is arranged so that the first metal foil is in contact with a surface of the first metal plate of the laminate, the first metal foil is made of a material that does not react at a contact surface of the first plate member and the first metal foil when heating, and a product of a Young's modulus (GPa) and a thickness (mm) of the first metal foil is 0.6 or more and 100 or less, so that a good bonded body can be manufactured by evenly pressurizing the laminate and foreign substances can be restrained from adhering to the surface of the laminate.

A bonded body according to an embodiment comprises a ceramic substrate, a copper plate, and a bonding layer provided on at least one surface of the ceramic substrate and bonding the ceramic substrate and the copper plate, in which the bonding layer contains Ag, Cu, Ti, and a first element being one or two selected from Sn and In, a Ti alloy of Ti and at least one selected from Ag, Cu, Sn, and In existing at a bonding boundary between the copper plate and the bonding layer, and the Ti alloy existing over not less than 30% per a length of 30 μm at the bonding boundary.

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 shock absorbing member 50 having a ceramic bonded body 15 having: a plurality of first sheet-like members 5 each having a ceramic containing 60 mass % or more of boron carbide and each having a thickness of 0.1 to 50 mm; and a bonding layer arranged between the first sheet-like members 5 adjacent to each other, the bonding layer bonding surfaces to be bonded facing each other of the first sheet-like members adjacent to each other, wherein the bonding layer has a bonding material containing at least one metal selected from the group consisting of aluminum, copper, silver, and gold.

A method of preparing a substrate having a wetting surface, including confirming the presence of an open, interconnected pore network in a ceramic substrate to be wetted with a first metal, filling the open, interconnected pore network with a second metal,

exuding the second metal to coat the surface of the substrate, and wetting the substrate with the first metal. The ceramic substrate is not decomposed by the first metal and the ceramic substrate is not decomposed by the second metal.

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.

A metal-ceramic substrate having at least one ceramic layer (2), which is provided on a first surface side (2a) with at least one first metallization (3) and on a second surface side (2b), opposite from the first surface side (2a), with a second metallization (4), wherein the first metallization (3) is formed by a film or layer of copper or a copper alloy and is connected to the first surface side (2a) of the ceramic layer (2) with the aid of a “direct copper bonding” process. The second metallization (4) is formed by a layer of aluminum or an aluminum alloy.

Provided are: an apparatus and a method for producing a (metal plate)-(ceramic board) laminated assembly, a bonding material and a metal plate during the bonding of the metal plate to the ceramic board through the bonding-material layer and an apparatus and a method for producing a power-module substrate. An apparatus for producing a (metal plate)-(ceramic board) laminated assembly by laminating a metal plate having a temporary bonding material formed thereon on a ceramic board having a bonding-material layer formed thereon, the apparatus being equipped with: a conveying device which conveys the metal plate onto the ceramic board to laminate the ceramic board and the metal plate on each other; and a heating device which is arranged in the middle of a passage of the conveyance of the metal plate by the conveying device and melts the temporary-bonding material on the metal plate.