Hoya Corporation

Hoya Glass Disk Vietnam II Ltd.

Wd Media (singapore) Pte. Ltd.

Kinobu Osakabe

Masanobu Itaya

Yoichi Hachitani

Mikio Ikenishi

Toshio Takizawa

Shinji Eda

Xuelu Zou

Kazuo Tachiwana

Hideki Isono

Naomi Matsumoto

Katsuyuki Iwata

Yoshitake Tanno

Kenichiro Terada

Kazuhiko Maeda

Kazuhiro Suzuki

Jun Ozawa

Junichi Horikawa

Katsutoshi Ono

Kong Kim

Nobuyuki Eto

Koji Takahashi

Shigeru Asanuma

Tomonari Hayashi

A substrate for a magnetic disk includes a substrate main body having two main surfaces and an outer circumferential edge surface, and a film that is an alloy film containing Ni and P and provided on a surface of the substrate main body. A disk shape of the substrate main body has an outer diameter of 90 mm or more. A thickness T of the substrate that includes film thicknesses of sections of the film provided on the main surfaces is 0.520 mm or less. A total thickness D mm, which is a sum of the film thicknesses of the sections of the film on the main surfaces and the thickness T mm satisfy D≥0.0082/T−0.0015. A surface roughness maximum height Rz of the film provided on the outer circumferential edge surface is smaller than that of the substrate main body at the outer circumferential edge surface.

Substrate for magnetic disk, magnetic disk, and hard disk drive apparatus

A magnetic-disk substrate has an average value of squares of inclinations that is 0.0025 or less, and a frequency at which squares of inclinations are 0.004 or more is 15% or less, in a case where samples of inclinations on a main surface are obtained at intervals of 10 nm. The main surface is configured to receive at least a magnetic recording layer thereon. The magnetic-disk substrate includes an outer circumferential end portion and an inner circumferential end portion, and the outer circumferential end portion and the inner circumferential end portion have chamfered portions.

Magnetic-disk substrate and magnetic disk

A substrate for a magnetic disk includes a substrate main body having a disk shape and an alloy film. The substrate has a thickness (T+D) of 0.520 mm or less, which is the sum of a thickness T of the substrate main body and a thickness D of the film formed on main surfaces of the substrate main body. The disk shape has an outer diameter of 90 mm or more. A ratio D/T of the thickness D to the thickness T is 0.025 or more. The thickness of the film formed on an outer circumferential edge surface of the substrate main body is greater than the thickness of the film formed on each of the main surfaces, and the thickness of the film formed on each of the main surfaces is 80% or more of the thickness of the film formed on the outer circumferential edge surface.

Substrate for magnetic disk and magnetic disk

A substrate for a magnetic disk includes a substrate main body having two main surfaces and an outer circumferential edge surface that has a side wall surface and chamfered surfaces, and a film that is an alloy film containing Ni and P and provided on a surface of the substrate main body. A disk shape of the substrate main body has an outer diameter of 90 mm or more. A thickness T of the substrate that includes the film provided on the main surfaces is 0.520 mm or less. A total thickness D mm of the film on the main surfaces and the thickness T mm satisfy D&#x2265;0.0082/T&#x2212;0.0015. A film thickness of the film on the outer circumferential edge surface is larger than a film thickness of the film on the main surfaces, and is 150% or less of the film thickness of the film on the main surfaces.

A ring-shaped glass spacer is configured to be arranged in contact with a magnetic disk in a hard disk drive apparatus. A surface resistivity of a surface of a glass material of the glass spacer at 22 (&#xb0; C.) is lower than a surface resistivity of an inner portion of the glass material at 22 (&#xb0; C.).

Glass spacer, hard disk drive apparatus, and method for manufacturing glass spacer

A magnetic-disk substrate has a pair of main surfaces, and an arithmetic average roughness Ra of each of the main surfaces is 0.11 nm or less. The arithmetic average roughness Ra is a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. The magnetic-disk substrate is made of glass or aluminum alloy.

Magnetic-disk substrate, magnetic disk, and magnetic-disk drive device

A non magnetic substrate for a magnetic disk includes a substrate main body having two opposing main surfaces and being a glass substrate main body or an aluminum alloy substrate main body, and a metal film made of an Ni&#x2014;P alloy and provided on the main surfaces and an outer circumferential edge surface of the substrate main body. The non magnetic substrate has a thickness (T+D) of 0.57 mm or less, which is the sum of a thickness T of the substrate main body and a thickness D of the metal film. The non magnetic substrate has a diameter of 90 mm or more. A ratio D/T is 0.025 or more. The outer circumferential edge surface of the substrate main body forming an interface with the metal film has a surface roughness maximum height Rz of 0.5 &#x3bc;m or more.

A substrate for a magnetic disk includes a substrate main body having two main surfaces, and a film that is provided on the main surfaces and is made of a material having a loss factor of 0.01 or more. The substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and a thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy a relationship D&#x2265;0.0082/T&#x2212;0.0015.

Substrate for magnetic disks, and magnetic disk

A hard disk drive includes a magnetic-disk substrate in which an average value of squares of inclinations is 0.0025 or less and a frequency at which squares of inclinations are 0.004 or more is 15% or less, in a case where samples of inclinations on a main surface are obtained at intervals of 10 nm.

Hard disk drive with magnetic-disk substrate and hard disk drive with magnetic disk

A glass material of a glass spacer has a surface resistivity of 10to 10(&#x3a9;/sq) at 22 (&#xb0; C.). The surface resistivity of a surface of the glass material of the glass spacer at 22 (&#xb0; C.) is lower than the surface resistivity of an inner portion of the glass material at 22 (&#xb0; C.). The glass spacer contains at least one oxide selected from the group consisting of TiO, NbO, WO, and BiO, as a glass component.

A non-magnetic substrate for a magnetic disk includes a substrate main body having two opposing main surfaces, and a metal film that is provided on the main surfaces and is made of a material having a loss factor of 0.01 or more. The non-magnetic substrate has a thickness (T+D) of 0.700 mm or less, the thickness (T+D) being the sum of a thickness T of the substrate main body and a thickness D of the metal film, and a ratio D/T of the thickness D of the metal film to the thickness T of the substrate main body is 0.025 or more.

Non-magnetic substrate for magnetic disk, and magnetic disk

A magnetic-disk glass substrate according to the present invention is a doughnut-shaped magnetic-disk glass substrate having a circular hole provided in the center, a pair of main surfaces, and an outer circumferential end surface and an inner circumferential end surface each including a side wall surface and a chamfered surface that is formed between each main surface and the side wall surface. A measurement point is provided on the outer circumferential end surface every 30 degrees in the circumferential direction with reference to a center of the glass substrate, and when a curvature radius of a shape of a portion between the side wall surface and the chamfered surface is determined at each measurement point, the difference in the curvature radius between neighboring measurement points is 0.01 mm or less.

A magnetic-disk substrate has a pair of main surfaces and arithmetic average roughnesses Ra of the main surfaces are each 0.11 nm or less. Also, in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of the surface unevenness is 25 nm/protrusion or less. The arithmetic average roughness Ra and the surface unevenness are measured using an atomic force microscope with a probe having a probe tip provided with a carbon nanofiber rod-shaped member.

Growing community of inventors

Tokorozawa, Japan

Kinobu Osakabe