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: 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: 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 ceramic assembled board is formed by cutting continuous dividing grooves on one or both of the surfaces of a sintered ceramic board by way of laser machining to produce a large number of circuit substrates and at least one of the continuous grooves has a largest depth section and a smallest depth section with a depth difference ?d of 10 ?m??d?50 ?m. A ceramic substrate is produced by dividing the ceramic assembled board and at least one of its lateral surfaces is a surface formed by dividing the ceramic assembled board along the continuous grooves, the arithmetic mean roughness Ra2 of the machined surfaces of the continuous grooves being smaller than the arithmetic mean roughness Ra1 of the surfaces of broken sections with regard to the arithmetic mean roughness Ra of the lateral surfaces.

Abstract: A ceramic assembled board shows an advantageous dividablility of allowing the board to be divided when intended and not allowing it to be divided with ease when unintended. A ceramic substrate shows an excellent degree of dimensional precision and bending strength. A ceramic circuit substrate shows a high dielectric strength. A ceramic assembled board is formed by cutting continuous dividing grooves on one or both of the surfaces of a sintered ceramic board by way of laser machining to produce a large number of circuit substrates and at least one of the continuous grooves has a largest depth section and a smallest depth section with a depth difference ?d of 10 ?m ??d?50 ?m.

Abstract: A high-density recording scanning microscope in which a beam of charged particles finely focused scans the surface of a sample at a high density of, at least, 8,000 scannings, a signal thus detected is converted into a digital signal, and the digital signal is used for directly printing an image of high definition, high gradation and wide view. The signal of a scanning image at a very high density of, at least, 8,000 pixels×8,000 pixels in a scanning electron microscope, is converted into a digital signal, for example, a color image, and the image is directly printed, thereby to realize the observation of a very clear image of high definition, high gradation and wide view having hitherto been nonexistent.