20results about "Base layer manufacture" patented technology

Disks for use in hard disk drives (HDD) or other magnetic recording apparatus. The disks are configured based on a finding that internal stress within a disk can make the disk more resistant to shock forces. In one example, a disk is provided that has a substrate with a thickness of no more than 0.5 millimeters and an internal stress no less than 300 megapascals. The relatively high internal stress within the substrate of the disk serves to reduce the magnitude of deflections caused by mechanical shocks to an HDD in which the disk is installed, as compared to other disks of equal thickness but with relatively less internal stress. Multi-platter stacks of the disks are described. Methods are also described for fabricating such disks and for rejecting disks that do not meet certain internal stress-based criteria. Substrates are also described.

To provide a method for producing a magnetic recording medium capable of having a magnetic layer with high crystal orientation and few defects, a magnetic recording medium, and a magnetic storage device.SOLUTION: A method of producing a magnetic recording medium 1 includes: a step of forming a magnesium oxide underlayer 20 on a surface of a substrate 10 by a sputtering method with using a target containing magnesium oxide; and a step of forming a magnetic layer 30 on the surface side of the magnesium oxide underlayer 20, in which the target containing the magnesium oxide is heated to more than 600°C when forming the magnesium oxide underlayer 20.SELECTED DRAWING: Figure 1

A method of manufacturing a magnetic recording medium includes burnishing, with an abrasive material, a surface of a stack including a magnetic recording layer and a protective layer stacked on a substrate in order of the magnetic recording layer and the protective layer. The burnishing of the surface of the stack includes using a long abrasive tape including abrasive grains as the abrasive material fixed onto a support in a state of being wound in roll form, and pressing the abrasive tape, supplied from the state of being wound in the roll form, against the surface of the stack so as to rub the surface of the stack. The abrasive tape in the state of being wound in the roll form is subjected to vacuum treatment in advance such that loose abrasive grains are reduced.

The present invention addresses the problem of providing a method for manufacturing a magnetic recording medium capable of improving the productivity of a magnetic recording medium. A method for manufacturing a magnetic recording medium according to the present invention comprises a polishing step for polishing the surface of a laminate in which a magnetic recording layer and a protective layer are laminated in this order on a substrate with a polishing material, the polishing step includes a step of using a long abrasive tape in a state in which abrasive grains, which are the abrasive material, are adhered to a support body, and pressing and rubbing the abrasive tape, which is supplied from the state in which the abrasive tape is wound in the state in which the abrasive tape is wound in the state in which the abrasive tape is wound in the state in which the abrasive tape is wound in the state in which the abrasive tape is wound in the state in which the abrasive tape is wound, against the surface of the laminate. The grinding belt in which abrasive grains that are dissociated by the vacuum treatment have been reduced in advance is used as the grinding belt that is wound in the roll shape.

A substrate for a magnetic disk, characterized by being composed of an aluminum alloy containing one or two or more of Fe: 8.5 mass% or less, Mn: 2.5 mass% or less, Ni: 6.5 mass% or less, and Mg: 4.5 mass% or less, with the remainder composed of Al and unavoidable impurities, a resonance frequency being f (Hz), a density being p (g / cm 3 ), and a plate thickness being t (mm), (f x p / t) being 3800 or more, and a magnetic disk using the substrate for a magnetic disk.

The present application relates to a kind of thin mechanical hard disk with aluminium round sheet, the aluminium round sheet thickness is 0.5~0.8mm, diameter is 95.0~98.2mm, surface flatness is less than 5 μm;The present application also relates to a kind of flatness control method of thin mechanical hard disk with aluminium round sheet, including the following steps: aluminium coiled material striping, stamping blanking, flattening and primary annealing treatment, rough grinding treatment, secondary annealing treatment, fine grinding treatment;Wherein aluminium round sheet is flattened and primary annealing treatment when pressure is 120‑200Kg, annealing heating rate is 80℃ / h~200℃ / h, cooling rate is 30℃ / h~70℃ / h after annealing ends, annealing holding temperature is 320°C~360°C, holding time is 2h~5h.The flatness value of aluminium round sheet of the present application is not higher than 5 μm, can guarantee the stable performance of mechanical hard disk, reduce the influence of mechanical hard disk disc in work, guarantee the stable flatness of aluminium round sheet, flatness has no rebound phenomenon, and the processing yield is high.

To provide a substrate for a magnetic disk, a magnetic disk, an annular-shaped substrate, and a manufacturing method for a substrate for a magnetic disk, to make it difficult for the annular-shaped substrate from a holding member that holds the annular-shaped substrate when double-sided grinding or polishing is performed on the annular-shaped substrate.SOLUTION: A glass substrate for a magnetic disk (magnetic disk substrate) 1 includes a pair of main surface 1p and outer peripheral end surface 5, the outer peripheral end surface has a pair of chamfered surfaces 1c, each of which is connected to the main surface, and a side wall surface 1t extending between the pair of chamfered surfaces and curved outwardly so as to be convex, and the side wall surface 1t has a radius of curvature Rt of 1100 μm or more in a cross-section along the plate thickness T direction of the magnetic disk substrate. To prevent the generation of fine particles, it is preferable that the outer peripheral end surface of the magnetic disk substrate is smoothed. In addition, it is preferable to align the outer peripheral end surface to a target shape.SELECTED DRAWING: Figure 2

A production method of a magnetic recording medium including a nonmagnetic substrate, a base layer over the nonmagnetic substrate, a seed layer over the base layer, and a magnetic recording layer over the seed layer. The production method of the magnetic recording medium includes forming the seed layer through a process including: forming a film including two elements, represented by element α and element β, such that the element α is mainly a columnar crystal having an fcc structure and the element β is mainly an amorphous structure; and etching a surface of the film to form a surface in which the element α and the element β are phase-separated from each other.

To provide a manufacturing method of a magnetic recording medium capable of further increasing the recording density by enhancing the perpendicular orientation of a magnetic recording layer, and to provide a magnetic recording and reproducing device equipped with the magnetic recording medium manufactured by the manufacturing method.SOLUTION: A method of manufacturing a magnetic recording medium according to the present invention is a method of manufacturing a magnetic recording medium including, on a non-magnetic substrate, an underlayer, a seed layer, and a magnetic recording layer in this order, wherein the seed layer is formed by forming a film containing two elements of an element α and an element β such that the element α mainly forms a columnar crystal having an fcc structure and the element β mainly forms an amorphous structure, and then etching a surface of the film to form a surface in which the element α and the element β are phase-separated from each other.SELECTED DRAWING: Figure 1

A non-metallic media substrate includes a disc-shaped substrate body having at least one media storage surface on a face thereof. The substrate body has a center opening having an inner diameter and an outer diameter surface, and the substrate body has a thickness. The substrate further includes an annular groove at the outer diameter of the media substrate, the annular groove having chamfered edges and an internal concavity extending toward the inner diameter.

The purpose of the present invention is to provide: a method for manufacturing a magnetic recording medium, which can improve the vertical orientation of a magnetic recording layer and can further increase the recording density; and a magnetic recording / reproducing device provided with a magnetic recording medium manufactured by the manufacturing method. The method for manufacturing a magnetic recording medium according to the present invention is a method for manufacturing a magnetic recording medium provided with an underlayer, a seed layer, and a magnetic recording layer in this order on a non-magnetic substrate, the seed layer being formed by forming a film containing two elements, i.e., an element [alpha] and an element [beta], the element [alpha] being mainly a columnar crystal having an fcc structure, and the element [beta] being mainly a columnar crystal having an fcc structure. After the film is formed such that the element [beta] mainly has an amorphous structure, the surface of the film is etched to form a surface in which the element [alpha] and the element [beta] are separated from each other.

The glass plate of one embodiment is a rectangular plate having a thickness of less than 0.68 mm. In this glass plate, the flatness of a square measurement area of 100 mm per side, said square measurement area being cut out from the center area of the glass plate excluding the edge areas on both of the long side direction and the short side direction of the glass plate, is 30 μm or less. When the measurement area is subjected to a first heat treatment in which the measurement area is maintained at 700°C for 4 hours and then cooled from 700°C to 400°C at a speed of 50°C / hour, the heat shrinkage of the measurement area is 130 ppm or less. When the measurement area is subjected to a second heat treatment in which the measurement area is maintained at Tg-160°C [wherein Tg (°C) stands for the glass transition temperature of the glass plate] for 60 seconds and then cooled to room temperature in air, the resulted amount of change in the flatness of the measurement area is 10 μm or less.

The present invention provides a glass substrate for magnetic disks that can suppress deterioration of flatness due to heat treatment for forming a magnetic recording layer, a disc-shaped glass used in such a glass substrate for magnetic disks, a glass plate, and a method for manufacturing a glass plate. [Solution] A rectangular glass plate with a thickness of less than 0.68 mm, wherein the flatness of a 100 mm square area to be measured, cut from the central region of the glass plate excluding the end regions on both sides in the short and long directions, is 30 μm or less; the thermal shrinkage rate of the area to be measured after a first heat treatment in which the area to be measured is maintained at 700°C for 4 hours and then cooled from 700°C to 400°C at a rate of 50°C / hour is 130 ppm or less; and when the glass transition temperature of the glass plate is expressed as Tg (°C), the change in the flatness of the area to be measured after a second heat treatment in which the area to be measured is maintained at Tg-160°C for 60 seconds and then cooled to room temperature in the air is 10 μm or less.

To provide a manufacturing method of a magnetic recording medium capable of enhancing productivity of the magnetic recording medium.SOLUTION: A method for manufacturing a magnetic recording medium according to the present invention includes a burnishing step of burnishing, with an abrasive, a surface of a laminate in which a magnetic recording layer and a protective layer are laminated in this order on a substrate, the burnishing step includes a step of using a long polishing tape in which abrasive grains are fixed as the polishing material on a support in a state of being wound in a roll shape, and pressing the polishing tape supplied from the state of being wound in a roll shape against the surface of the laminate to rub the surface, in which the polishing tape in which free abrasive grains are reduced by performing a vacuum treatment in advance is used as the polishing tape in the state of being wound in a roll shape.SELECTED DRAWING: Figure 2

The present invention intends to provide a magnetic disk that is flat while being thin and hardly causes physical errors.The present invention provides a magnetic disk having a hole in the center, a thickness of 0.60 mm or less, TIRs on circles having different radial distances r1 (mm) and r2 (mm) denoted by TIR1 (μm) and TIR2 (μm), and an amount of radial variation ΔTIR for TIRs of 0.50 μm / mm or less in an outer circumferential region of the magnetic disk with r / R=0.70 to 0.99, where “R” is a disk radius (mm), “r” is a radial distance (mm) measured from the disk center, and the ΔTIR is represented by an absolute value |(TIR1−TIR2) / (r1−r2)| of the ratio of the difference (TIR1−TIR2) between the TIR1 and the TIR2 to the difference (r1−r2) between r1 and r2 of the magnetic disk.

In a method for manufacturing a glass plate that includes chamfering processing for chamfering an edge surface of a glass plate, the chamfering processing includes a step of forming a chamfered surface by irradiating the edge surface of the glass plate with a laser beam, and a step of heating the glass plate before the chamfered surface is formed. When a temperature of the glass blank at which the glass blank is heated is Tp [° C.], a glass transition point of the glass blank is Tg [° C.], and an average coefficient of linear thermal expansion of the glass blank is α [1 / ° C.], (Tg−Tp)≤−5.67×107·α+840 is satisfied.

An annular glass plate has an outer circumferential edge surface, an inner circumferential edge surface, and a thickness not larger than 0.6 mm. The outer circumferential edge surface and the inner circumferential edge surface are constituted by molten surfaces. The molten surfaces in the outer circumferential edge surface and the inner circumferential edge surface each have an arithmetic average surface roughness Ra not larger than 0.1 μm and the surface roughness of the molten surface in the inner circumferential edge surface is larger than the surface roughness of the molten surface in the outer circumferential edge surface. The molten surfaces in the inner circumferential edge surface and the outer circumferential edge surface do not bulge relative to both main surfaces of the annular glass plate.

The present invention intends to provide a substrate for a magnetic disk and a method for manufacturing same, and a magnetic disk capable of holding high flatness after long-term use despite being thin, coping with a high capacity of hard disk, and improving long-term reliability thereof. In the substrate according to the present invention, when a process for heating a substrate at 120° C. for 30 minutes and then cooling the substrate at −40° C. for 30 minutes is defined as one cycle, the flatness PV of a surface of the substrate measured at 25° C. after a thermal impact test in which the cycle is repeatedly performed 200 times is not more than 12 μm. The present invention further encompasses a magnetic disk having a similar flatness PV under the same conditions. The present invention still further encompasses a method for manufacturing the substrate for a magnetic disk.

A magnetic disk substrate includes an aluminum alloy including one type or two or more types of Fe: 8.5 mass % or less, Mn: 2.5 mass % or less, Ni: 6.5 mass % or less, and Mg: 4.5 mass % or less, a balance being Al and unavoidable impurities, wherein, when f (Hz) is a resonance frequency, ρ (g / cm3) is a density, and t (mm) is a plate thickness, (f×ρ / t) is 3800 or greater; and a magnetic disk using the magnetic disk substrate.

When a laser beam is used to perform shape processing on an edge surface of a disk-shaped glass plate, in order to suppress strain (retardation values) in the main surface of the glass plate, the disk-shaped glass plate is floated above a base, and the edge surface of the glass plate is processed into a target shape by irradiating the edge surface with the laser beam while contactlessly heating the glass plate in a state where the glass plate is floated, and moving the laser beam relative to the edge surface in the circumferential direction of the disk-shaped glass plate.