Nihon Micro Coating Co., Ltd.

Hiromitsu Okuyama

Yuji Horie

Kazuei Yamaguchi

Tatsuya Tanifuji

Mitsuo Otohata

A method of texturing a surface of a magnetic hard disk substrate includes the steps of rotating the magnetic hard disk substrate, supplying polishing slurry on the surface of the substrate, and pressing a polishing tape on the substrate surface and running the polishing tape. The polishing slurry includes abrading particles of monocrystalline diamond that are cluster particles with corners having diameters in the range of 1-10 nm, dispersed in a dispersant such as water and a water-based aqueous solution. The cluster particles are tasseled assemblies of crystalline particles with no directionality.

Method of texturing

A disk processing device holds and rotates a disk with a spindle. Processing tapes are supplied out and wound up by a tape reel unit so as to sandwich and be pressed on both surfaces of the disk through contact rollers. As a crankshaft is rotated, a sliding plate rotates around it and a slidable shaft rotates around a fulcrum part while sliding along the sliding plate such that the contact roller undergoes a reciprocating motion in a radial direction of the disk together with a slider rotatably attached to the slidable shaft.

Disk processing device and method

A polishing cloth to be produced has a surface layer stacked over a base material. The surface layer is made of a foamed layer and a non-foamed layer, the foamed layer including air bubble cells and the non-foamed layer having an externally exposed surface where linear cuts are formed. These linear cuts reach the air bubble cells such that the air bubble cells communicate with the exterior through the linear cuts. These linear cuts are controlled to be 10 &#x3bc;m or less in length. Such a polishing cloth is produced by applying a foamable coating material such as a foamable resin over a surface of the base material, foaming the foamable coating material to form the surface layer, and forming the linear cuts through the non-foamed layer.

Method of producing polishing cloth

Polishing slurry for texturing the surface of a magnetic hard disk substrate has abrading particles with diameters in the range of 1-10 nm dispersed in a dispersant such as water and a water-based aqueous solution. The abrading particles may be monocrystalline diamond particles, polycrystalline diamond particles or cluster particles with monoerystalline and polycrystalline diamond particles.

Polishing slurry for texturing

A polishing cloth has a surface layer stacked over a base material. The surface layer is made of a foamed layer and a non-foamed layer, the foamed layer including air bubble cells and the non-foamed layer having an externally exposed surface where linear cuts are formed. These linear cuts reach the air bubble cells such that the air bubble cells communicate with the exterior through the linear cuts. These linear cuts are controlled to be 10 &#x3bc;m or less in length.

Polishing cloth

A magnetic hard disk substrate is produced by rotating an aluminum substrate or a glass substrate, supplying polishing slurry on its surface, pressing a polishing tape on the surface and running it in a direction opposite to the direction of rotation of the substrate. Texturing marks are formed with a line density greater than 70 lines/&#x3bc;m in the radial direction on the surface. The polishing slurry has abrading particles dispersed in a dispersant. The abrading particles may be monocrystalline diamond particles, polycrystalline diamond particles or cluster particles with such monocrystalline and polycrystalline diamond particles with diameters in the range of 1-50 nm. Agglomerated particles of such cluster particles that are agglomerated in the dispersant may also be included as the abrading particles.

Method of producing magnetic hard disk substrate

A polishing tape makes use of a foamed material such as polyurethane foam attached to a plastic backing material. The foamed material is elastic and some of its gas holes formed inside but near one of its surfaces are exposed externally. Because of its elastic nature, it can be deformed even if there are abnormally large abrading particles contained in a liquid slurry and such abrading particles do not become embedded in the target surface being textured. These externally exposed gas holes can also serve to absorb the debris generated by the texturing and to protect the target surface from being scratched thereby. Such a tape is used for a texturing process while dropping a liquid slurry containing abrading particles and rotating the disk substrate and pressing the tape against the target surface.

Method of producing magnetic hard disk substrate with textured surface

An agent used for texturing a surface of a substrate for a magnetic disk includes an aqueous solution containing a glycol compound serving as surfactant in an amount of about 1-25 weight % and agglomerated polycrystalline diamond particles with average diameter of 0.01-2 &mgr;m in an amount of 0.001-3 weight % formed with very small polycrystalline diamond particles with average diameter of 1-20 nm. When the substrate surface is textured, the substrate is rotated, the agent is supplied to the target surface to be textured and a polishing tape is pressed and run against it. A substrate thus processed has a surface with very fine and uniform textured lines without any abnormal protrusions.

Method of texturing and agent therefor

Polishing tape

Polishing compositions with phosphoric ester added to a suspension containing abrasive particles can have an improved ability to have the abrasive particles dispersed again after they are left for an extended period of time such that the particles may have condensed into aggregates. Those with abrasive particles such as diamond powder dispersed in an aqueous solution containing a glycol compound, metallic salt of a higher aliphatic acid and phosphoric ester have an improved polishing ability.

Growing community of inventors

Tokyo, Japan

Hiromitsu Okuyama