Abstract: Provided is a large-sized silicon nitride sintered substrate and a method for producing the same. The silicon nitride sintered substrate has a main surface 101a of a shape larger than a square having a side of a length of 120 mm. A ratio dc/de of the density dc of the central area and the density de of the end area of the main surface 101a is 0.98 or higher. The void fraction vc of the central area of the main surface 101a is 1.80% or lower, and the void fraction ve of the end area is 1.00% or lower. It is preferred that the density dc of the central area is 3.120 g/cm3 or higher, the density de of the end area is 3.160 g/cm3 or higher, and a ratio ve/vc of the void fraction vc of the central area and the void fraction ve of the end area is 0.50 or higher.

Abstract: In order to address the problem in that, by increasing the gate resistance of a power semiconductor element, while variation of switching time can be controlled, loss due to the gate resistance becomes larger and power efficiency for the entire system is lowered, the present invention provides an insulating substrate capable of uniformizing switching speeds of circuit elements while suppressing influence on power efficiency of the circuit elements. In the insulating substrate according to the present invention, part of a wiring layer is formed as a control signal circuit layer, and part of the control signal circuit layer is formed as a resistance layer that increases input resistance when the circuit element receives a control signal.

Abstract: In order to address the problem in that, by increasing the gate resistance of a power semiconductor element, while variation of switching time can be controlled, loss due to the gate resistance becomes larger and power efficiency for the entire system is lowered, the present invention provides an insulating substrate capable of uniformizing switching speeds of circuit elements while suppressing influence on power efficiency of the circuit elements. In the insulating substrate according to the present invention, part of a wiring layer is formed as a control signal circuit layer, and part of the control signal circuit layer is formed as a resistance layer that increases input resistance when the circuit element receives a control signal.

Abstract: Provided is a large-sized silicon nitride sintered substrate and a method for producing the same. The silicon nitride sintered substrate has a main surface 101a of a shape larger than a square having a side of a length of 120 mm. A ratio dc/de of the density dc of the central area and the density de of the end area of the main surface 101a is 0.98 or higher. The void fraction vc of the central area of the main surface 101a is 1.80% or lower, and the void fraction ve of the end area is 1.00% or lower. It is preferred that the density dc of the central area is 3.120 g/cm3 or higher, the density de of the end area is 3.160 g/cm3 or higher, and a ratio ve/vc of the void fraction vc of the central area and the void fraction ve of the end area is 0.50 or higher.

Abstract: A method for producing a ceramic circuit substrate comprising the steps of forming brazing regions each comprising brazing material powder and an organic binder on a ceramic substrate; setting metal plates on the ceramic substrate via the brazing regions, and heating the ceramic substrate, the brazing regions and the metal plates to bond the metal plates to the ceramic substrate via brazing layers made of the brazing material, thereby forming a bonded body; and cleaning the bonded body with a hypochlorite-containing agent.

Abstract: To provide a brazing material for maintaining bonding strength between ceramic substrate and metal plate at a conventionally attainable level, while addition amount of In is reduced, and a brazing material paste using the same. A mixture powder provided by mixing alloy powder composed of Ag, In, and Cu, Ag powder, and active metal hydride powder, the mixture powder containing active metal hydride powder with a 10-to-25-?m equivalent circle average particle diameter by 0.5 to 5.0 mass %, the equivalent circle average particle diameters for the alloy powder, Ag powder, and active metal hydride powder having a relationship: alloy powder?active metal hydride powder>Ag powder, and the powder mixture having a particle size distribution of d10 of 3 to 10 ?m, d50 of 10 to 35 ?m, and d90 of 30 to 50 ?m, and in the frequency distribution, a peak of the distribution existing between d50 and d90.

Abstract: A method for producing a ceramic circuit substrate comprising the steps of forming brazing regions each comprising brazing material powder and an organic binder on a ceramic substrate; setting metal plates on the ceramic substrate via the brazing regions, and heating the ceramic substrate, the brazing regions and the metal plates to bond the metal plates to the ceramic substrate via brazing layers made of the brazing material, thereby forming a bonded body; and cleaning the bonded body with a hypochlorite-containing agent.

Abstract: A manufacturing method with which a high thermal conductivity silicon nitride substrate having excellent sintering performance can be manufactured without the occurrence of a molding crack or degreasing crack, as well as to provide a silicon nitride substrate, and a silicon nitride circuit board and a semiconductor module using the silicon nitride substrate. In the manufacturing method, in which a slurry is produced by mixing a silicon nitride powder, a sintering additive powder, and a binder in an organic solvent which is a dispersion medium, and the slurry is formed into a sheet, followed by degreasing and sintering, the oxygen content of the silicon nitride powder is 2.0 mass % or less and the specific surface area of the same is 3 to 11 m2/g, the additive ratio of the sintering additive powder is 4 to 15 mol %, and the water content ratio of the organic solvent is 0.03 to 3 mass %.

Abstract: To provide a brazing material for maintaining bonding strength between ceramic substrate and metal plate at a conventionally attainable level, while addition amount of In is reduced, and a brazing material paste using the same. A mixture powder provided by mixing alloy powder composed of Ag, In, and Cu, Ag powder, and active metal hydride powder, the mixture powder containing active metal hydride powder with a 10-to-25-?m equivalent circle average particle diameter by 0.5 to 5.0 mass %, the equivalent circle average particle diameters for the alloy powder, Ag powder, and active metal hydride powder having a relationship: alloy powder?active metal hydride powder>Ag powder, and the powder mixture having a particle size distribution of d10 of 3 to 10 ?m, d50 of 10 to 35 ?m, and d90 of 30 to 50 ?m, and in the frequency distribution, a peak of the distribution existing between d50 and d90.

Abstract: A circuit board and a semiconductor module with high endurance against thermal cycles, and which is hard to be broken under thermal cycles, even if thick metal circuit board and thick metal heat sink are used, corresponding to high power operation of a semiconductor chip are provided. This circuit board includes, an insulating-ceramic substrate, a metal circuit plate bonded to one face of the insulating-ceramic substrate, a metal heat sink bonded to another face of the insulating-ceramic substrate, wherein (t12?t22)/tc2/K<1.5, where, a thickness of the insulating ceramics substrate is tc, a thickness of the metal circuit plate is t1, a thickness of the metal heat sink is t2, and an internal fracture toughness value of the insulating ceramics substrate is K.

Abstract: Provided is a manufacturing method with which a high thermal conductivity silicon nitride substrate having excellent sintering performance can be manufactured without the occurrence of a molding crack or degreasing crack, as well as to provide a silicon nitride substrate, and a silicon nitride circuit board and a semiconductor module using said silicon nitride substrate. In this silicon nitride substrate manufacturing method, in which a slurry is produced by mixing a silicon nitride powder, a sintering additive powder, and a binder in an organic solvent which is a dispersion medium, and the slurry is formed into a sheet, followed by degreasing and sintering, the oxygen content of the silicon nitride powder is 2.0 mass % or less and the specific surface area of the same is 3 to 11 m2/g, the additive ratio of the sintering additive powder is 4 to 15 mol %, and the water content ratio of the organic solvent is 0.03 to 3 mass %.

Abstract: In the silicon nitride substrate concerning an embodiment of the invention, degree of in-plane orientation fa of ? type silicon nitride is 0.4-0.8. Here, degree of in-plane orientation fa can be determined by the rate of the diffracted X-ray intensity in each lattice plane orientation in ? type silicon nitride. As a result of research by the inventors, it turned out that both high fracture toughness and high thermal conductivity are acquired, when degree of in-plane orientation fa was 0.4-0.8. Along the thickness direction, both the fracture toughness of 6.0 MPa·m1/2 or higher and the thermal conductivity of 90 W/m·K or higher can be attained.

Abstract: An object of this invention is to get a circuit board and a semiconductor module with high endurance against thermal cycles, and which is hard to be broken under thermal cycles, even if thick metal circuit board and thick metal heat sink are used, corresponding to high power operation of semiconductor chip. This circuit board comprises, an insulating-ceramic substrate, a metal circuit plate bonded to one face of the insulating-ceramic substrate, a metal heat sink bonded to another face of the insulating-ceramic substrate, wherein (t12?t22)/tc2/K<1.5, here, thickness of the insulating ceramics substrate is tc, thickness of the metal circuit plate is t1, thickness of the metal heat sink is t2, and internal fracture toughness value of the insulating ceramics substrate is K.

Abstract: In the silicon nitride substrate concerning an embodiment of the invention, degree of in-plane orientation fa of ? type silicon nitride is 0.4-0.8. Here, degree of in-plane orientation fa can be determined by the rate of the diffracted X-ray intensity in each lattice plane orientation in ? type silicon nitride. As a result of research by the inventors, it turned out that both high fracture toughness and high thermal conductivity are acquired, when degree of in-plane orientation fa was 0.4-0.8. Along the thickness direction, both the fracture toughness of 6.0 MPa·m1/2 or higher and the thermal conductivity of 90 W/m·K or higher can be attained.

Abstract: A power semiconductor module has a silicon nitride insulated substrate, a metal circuit plate made of Cu or a Cu alloy, which is disposed on one surface of the silicon nitride insulated substrate, a semiconductor chip mounted on the metal circuit plate, and a heat dissipating plate made of Cu or a Cu alloy, which is disposed on the other surface of the silicon nitride insulated substrate; a carbon fiber-metal composite made of carbon fiber and Cu or a Cu alloy is provided between the silicon nitride insulated substrate and the metal circuit plate; the thermal conductivity of the carbon fiber-metal composite in a direction in which carbon fiber of the carbon fiber-metal composite is oriented is 400 W/m·k or more. Accordingly, a power semiconductor module that has a low thermal resistance between the semiconductor chip and a heat dissipating mechanism and also has improved cooling capacity is provided.

Abstract: A semiconductor device having both high strength and high thermal radiation that is capable of being applied to mounting on automobiles experiencing many thermal cycles, and a manufacturing method thereof are provided. A circuit board 1a for a resin encapsulated semiconductor module device has a configuration where a silicon nitride plate 2 with a thickness of 0.635 mm has copper plates of 1.0 mm and 0.8 mm bonded to both sides thereof via active metal. A copper plate 3a is bonded to the surface side of the silicon nitride plate 2, and a prescribed circuit pattern is formed on the copper plate 3a. Tin-silver-copper cream solder layers 4a and 4b with a thickness of 200 ?m are formed at a prescribed location on the circuit pattern 3a on which a semiconductor element 6 is mounted and at a prescribed location of a base plate 1 on which the circuit board 1a is disposed.

Abstract: A silicon nitride sintered body comprising Mg and at least one rare earth element selected from the group consisting of La, Y, Gd and Yb, the total oxide-converted content of the above elements being 0.6–7 weight %, with Mg converted to MgO and rare earth elements converted to rare earth oxides RExOy. The silicon nitride sintered body is produced by mixing 1–50 parts by weight of a first silicon nitride powder having a ?-particle ratio of 30–100%, an oxygen content of 0.5 weight % or less, an average particle size of 0.2–10 ?m, and an aspect ratio of 10 or less, with 99–50 parts by weight of ?-silicon nitride powder having an average particle size of 0.2–4 ?m; and sintering the resultant mixture at a temperature of 1,800° C. or higher and pressure of 5 atm or more in a nitrogen atmosphere.

Abstract: There is provided a thinner high frequency power module structure having reduced the mounting area. An insulated board is provided with a composite metal board in which the Cu2O powder particles are dispersed into a matrix metal (Cu) (amount of addition of Cu2O: 20 vol %; thermal expansion coefficient: 10.0 ppm/° C.; thermal conductivity: 280 W/m•K; thickness: 1 mm; size: 42.4×85 mm), a silicon nitride board (thermal expansion coefficient: 3.4 ppm/° C.; thermal conductivity: 90 W/m•K; thickness: 0.3 mm; size: 30×50 mm) deposited with Ag-system bonding metal layer to one principal surface of the composite metal board, and a wiring metal board formed of copper or copper alloy provided to the other principal surface of the ceramics insulated board. For example, the bonding metal layer is adjusted in the thickness to 50 ?m, while the wiring metal board is also adjusted in the thickness to 0.4 mm.

Abstract: A semiconductor device having both high strength and high thermal radiation that is capable of being applied to mounting on automobiles experiencing many thermal cycles, and a manufacturing method thereof are provided. A circuit board 1a for a resin encapsulated semiconductor module device has a configuration where a silicon nitride plate 2 with a thickness of 0.635 mm has copper plates of 1.0 mm and 0.8 mm bonded to both sides thereof via active metal. A copper plate 3a is bonded to the surface side of the silicon nitride plate 2, and a prescribed circuit pattern is formed on the copper plate 3a. Tin-silver-copper cream solder layers 4a and 4b with a thickness of 200 ?m are formed at a prescribed location on the circuit pattern 3a on which a semiconductor element 6 is mounted and at a prescribed location of a base plate 1 on which the circuit board 1a is disposed.

Abstract: A silicon nitride sintered body comprising Mg and at least one rare earth element selected from the group consisting of La, Y, Gd and Yb, the total oxide-converted content of the above elements being 0.6-7 weight %, with Mg converted to MgO and rare earth elements converted to rare earth oxides RExOy. The silicon nitride sintered body is produced by mixing 1-50 parts by weight of a first silicon nitride powder having a ?-particle ratio of 30-100%, an oxygen content of 0.5 weight % or less, an average particle size of 0.2-10 ?m, and an aspect ratio of 10 or less, with 99-50 parts by weight of ?-silicon nitride powder having an average particle size of 0.2-4 ?m; and sintering the resultant mixture at a temperature of 1,800° C. or higher and pressure of 5 atm or more in a nitrogen atmosphere.