Showa Denko K.k.

Citizen Seimitsu Co., Ltd.

Kazuyuki Haneda

Katsuaki Aida

Hiroyuki Machida

Satoshi Fujinami

Yosuke Sato

Takeshi Jonouchi

Kunizo Watanabe

Yoshio Kawakami

The polishing method of a disk-shaped substrate for polishing an outer circumferenceof a disk-shaped substrate using slurry is provided with in this sequence: a first polishing process for polishing the outer circumferenceusing an abrasive-grain inclusion brushmade of a resin in which polishing abrasive grains are included; and a second polishing process for polishing the outer circumferenceusing a resin brushmade of a resin in which the polishing abrasive grains are not included.

Polishing method and polishing apparatus

The disk-shaped substrate manufacturing method is provided with: generating an air stream downward from an upper area during grinding a disk-shaped substrate in a grinding apparatus; arranging the grinding apparatus on an upper floor face of a floor and arranging water on a lower floor face of the floor, the upper floor face being made of a board having penetration holes or a mesh member, and the lower floor face supporting the upper floor face so as to be located above the lower floor face with a distance; and guiding dust made by the grinding apparatus to the water by use of the air stream.

Disk-shaped substrate manufacturing method

The grinding method of a disk-shaped substrate that grinds a disk-shaped substrate including a portion having a hole at the center thereof while rotating the disk-shaped substrate is provided with: grinding an inner circumference of the disk-shaped substrate while an inner circumference grinding device is fed in a radial direction toward an outer circumference of the disk-shaped substrate and grinding the outer circumference of the disk-shaped substrate while an outer circumference grinding device is fed in the radial direction toward the inner circumference of the disk-shaped substrate; and stopping the feedings of the inner circumference grinding device and the outer circumference grinding device at the same time.

Grinding method of a disk-shaped substrate and grinding apparatus

The present invention provides a low-cost polishing slurry having excellent effect with respect to defects and smoothness of the surface to be polished. The polishing slurry comprises a silica abrasive and a ceria abrasive, wherein the silica abrasive content is less than 3 mass % and the ceria abrasive content is less than 1 mass %, based on the entire polishing slurry. Further, the present invention provides a method for producing a crystallized glass substrate for an information recording medium, wherein the method use a polishing slurry of the present invention. Furthermore, the present invention provides a method for producing an information recording medium, comprising forming a recording layer on a crystallized glass substrate for an information recording medium obtained by the present method.

Polishing slurry, production method of glass substrate for information recording medium and production method of information recording medium

The disk-shaped substrate inner circumference polishing method for polishing an inner circumference of a disk-shaped substrate including a portion having an opening hole at the center thereof includes inserting a brush having a shaft core into the portion having the opening hole of the disk-shaped substrate; fixing one end and the other end of the brush to a pair of rotating shafts that are provided at mutually detached positions and pulling at least any one of the one end and the other end of the brush and applying tension in the axial direction to the shaft core of the brush; and rotating the brush and polishing the inner circumference of the disk-shaped substrate.

Disk-shaped substrate inner circumference polishing method

The polishing apparatus that polishes an inner circumferential surface of a disk-shaped substrate including a portion having a hole at the center thereof, the polishing apparatus is provided with: a rotating table that holds piled workpieces in which a plurality of disk-shaped substrates are piled, a polishing brush that is inserted into a portion having the hole of the disk-shaped substrates of the piled workpieces and is rotated, a cover member that covers the piled workpieces, and a polishing-liquid flowing-in unit that flows polishing liquid into the portion having the hole of the disk-shaped substrates of the piled workpieces covered by the cover member.

Polishing apparatus, polishing brush and manufacturing method of disk-shaped substrate

A process for manufacturing a glass substrate for a magnetic recording medium comprising polishing a crystallized glass substrate using abrasive grains, and then washing the substrate using an aqueous organic carboxylic acid solution; a glass substrate for a magnetic recording medium which is manufactured by the process; and a magnetic recording medium obtained using the substrate. A glass substrate for a magnetic recording medium is manufactured, whereby the surface roughness is low and the surface defects are minimal for washing after polishing of a crystallized glass substrate, and wherein the Read-Write performance are not impaired when a recording layer including a magnetic film is formed on the magnetic recording medium substrate for manufacturing a magnetic recording medium.

Process for manufacturing glass substrate for magnetic recording medium, glass substrate for magnetic recording medium obtained by the process, and magnetic recording medium obtained using the substrate

The invention provides a magnetic disk glass substrate capable of preventing the occurrence of dust and adhesion of particles to the magnetic disk surface during a magnetic disk production process, a production method and a magnetic disk. A glass substrate for a magnetic disk has a construction in which an outer peripheral edge shape formed around a peripheral edge portion of a main surface has, with another flat portion of the main surface being the reference:

Magnetic disk substrate and production method of magnetic disk

The object of the invention is to provide a method of polishing the end surfaces of a substrate for a recording medium, which is capable of efficiently polishing the inner peripheral end surface and/or the outer peripheral end surface of the substrate preventing the reliability of performance of the recording medium from being impaired by the adhesion of the residual polishing material. According to the invention, there is provided a method of polishing end surfaces of a substrate for a recording medium wherein an inner peripheral end surface or an outer peripheral end surface of a substrate for a disk-like recording medium having a circular hole at the central portion thereof is brought into contact with a polishing medium obtained by dispersing polishing grains in a viscoelastic resin carrier and the polishing medium flows, thereby to polish the inner peripheral end surface or the outer peripheral end surface.

Method of polishing end surfaces of a substrate for a recording medium by a grain flow processing method

To provide a substrate which is not substantially chipped or cracked on the substrate end faces even when the substrate is a silicon substrate made of a brittle material, and provide a substrate which prevents dust raising from the substrate end faces and prevents dust raising due to rubbing with a processing cassette. A silicon substrate for a magnetic recording medium is formed by setting the lengths L of chamfered portions between the main surfaces of the substrate and the outer circumferential side end face to 0.1&#xb1;0.03 mm and setting the angles &#x3b1; between the main surfaces and the chamfered portions between the main surfaces and the outer circumferential side end face to 45 degrees &#xb1;5 degrees. It is also possible for a curved portion with a radius of 0.01 mm or more and less than 0.3 mm is interposed between the main surfaces and the outer circumferential side chamfered portions of the substrate.

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Ichihara, Japan

Kazuyuki Haneda