A silicon nitride substrate includes silicon nitride and magnesium, in which when a surface of the silicon nitride substrate is analyzed with an X-ray fluorescence spectrometer under the specific Condition I, XB/XA is 0.8 or more and 1.0 or less.

A joint body of the present disclosure includes a substrate including a base member having insulating properties and a metal layer positioned on a first main surface of the base member, a metal joint layer, and a metal member. The metal joint layer is positioned between the metal layer and the metal member of the substrate. The metal joint layer includes a nickel layer, a solder layer, and a composite layer containing a mix of nickel and solder. The nickel layer, the composite layer, and the solder layer are positioned in this order from the metal layer side to the metal member side. The nickel in the composite layer extends from the nickel layer in the thickness direction and forms protrusions and recesses.

A carrier substrate (1) that includes an insulation layer (11) and a metal layer (12), wherein a flank profile (2), in particular an etching flank profile, at least zonally borders the metal layer (12) in a primary direction (P) extending parallel to the main extension plane (HSE), wherein, viewed in the primary direction (P), the flank profile (2) extends from a first edge (15) on an upper side (31) of the metal layer (12), which faces away from the insulation layer (11), to a second edge (16) on a lower side (32) of the metal layer (12), which faces the insulation layer (11), characterized in that the flank profile (2), viewed in the primary direction (P), has at least one local maximum (21) and at least one local minimum (22).

A second main surface of the copper plate is opposite a first main surface of the copper plate, and is bonded to a silicon nitride ceramic substrate by the bonding layer. A first portion and a second portion of an end surface of the copper plate form an angle of 135° to 165° on an outside of the copper plate. An extended plane of the first portion and the second main surface form an angle of 110° to 145° a side where the second portion is located. A distance from the second main surface to an intersection of the first portion and the second portion in a direction of a thickness of the copper plate is 10 to 100 μm. The second main surface extends beyond the extended plane of the first portion by a distance of 10 μm or more.

A ceramic-copper composite having a flat plate shape, including: a ceramic layer; a copper layer; and a brazing material layer present between the ceramic layer and the copper layer. When a region having a length of 1,700 μm in a long-side direction is a region P on a cut surface of the ceramic-copper composite obtained when the ceramic-copper composite is cut with a plane perpendicular to a main surface of the ceramic-copper composite, an average crystal grain size D1 of copper crystals at least partially present in a region P1 within 50 μm on a side of the copper layer from an interface between the ceramic layer and the brazing material layer in the region P is 30 μm or more and 100 μm or less.

A method of producing a copper/ceramic bonded body, the copper member having a composition having a Cu purity of 99.96 mass % or more, a balance of inevitable impurities, a P content of 2 mass ppm or less, and a total content of Pb, Se and Te of 10 mass ppm or less, the method includes bonding the laminated copper member and the ceramic member by pressing and heating, wherein an average crystal grain size of the copper member before bonding is 10 μm or more, an aspect ratio is 2 or less, and a pressing load is 0.05 MPa or more and 1.5 MPa or less, a heating temperature is 800° C. or higher and 850° C. or lower, and a holding time at the heating temperature is 10 minutes or longer and 90 minutes or shorter.

A sealing composition which can be handled in a semi-cured state and can obtain a sintered body having excellent joining strength and sealing performance is provided. A sealing composition including a solder powder, coated silver particles including silver core particles and a coating agent arranged on a surface of the silver core particles, and a solvent is provided. Further, a sintering temperature (T2) of the coated silver particles and a boiling point (T3) of the solvent satisfy T2≤T3.

A copper/ceramic bonded body includes: a copper member made of copper or a copper alloy; and a ceramic member made of an aluminum nitride, wherein, the copper member and the ceramic member are bonded to each other, and a Mg solid solution layer is provided between the copper member and the ceramic member and contains Mg in a state of a solid solution in a Cu primary phase.

An intermediate member is a member which is directly or indirectly sandwiched between a first object and a second object. The intermediate member includes a plate-like supporting member having a lower surface which is one main surface opposed to the first object and a plurality of ceramic blocks fixed on an upper surface which is the other main surface of the supporting member in a state of being separated from one another. Thus, in a state where the plurality of ceramic blocks are collectively held by the supporting member having relatively high shape retention, by disposing the intermediate member between the objects, it is possible to easily arrange the plurality of ceramic blocks between the objects with high positioning accuracy.

After a copper plate 14 is bonded to at least one surface of a ceramic substrate 10 via an active metal containing brazing filler metal 12 which contains silver, the unnecessary portion of the copper plat 14 and active metal containing brazing filler metal 12 is removed, and thereafter, an unnecessary portion of the copper plate 14 is removed by chemical polishing so as to cause the active metal containing brazing filler metal 12 to protrude from the side face portion of the copper plate 14, and then, a silver layer 18 adhered to the surface of the copper plate 14 by the chemical polishing is removed.