JPH10334461A - Manufacture of magnetic recording medium substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity and material yield by reducing chipping, cracking or omission in the cutting of a magnetic recording medium substrate. SOLUTION: In the manufacture of magnetic recording medium substrate for manufacturing a doughnut type or a disk magnetic recording medium substrate by cutting it from a plate-like base material having a diameter larger than that of the substrate, a base material 1 made of a brittle material is fixed to a fixing jig 2 having a previously formed groove 4 therein with width equivalent to a width obtained by adding a thickness by 0 to 5 times to the cutter thickness at the base material cutting part and the cutting is made by using a cup-like core drill 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium substrate.

[0002]

2. Description of the Related Art With the development of portable computers, such as notebook personal computers, magnetic recording media are desired to have a recording device that is small and resistant to shocks. It is rare.
In such a magnetic recording medium, most of mechanical properties such as strength, surface smoothness, warpage, and weight of the recording medium depend on the substrate. Conventionally, aluminum alloys have been used as substrates for magnetic recording media, but with the increase in recording density, rigid substrates with smaller surface roughness, better abrasion resistance and better impact resistance have been required. A representative brittle material has been used for a magnetic recording medium substrate.

On the other hand, it has been proposed to use single crystal silicon for a magnetic recording medium substrate (see Japanese Patent Publication No. 2-41089 and Japanese Patent Laid-Open No. 6-68463). There is an advantage that the infrared heater used for the above requires less power, the substrate is hardly warped by heating the substrate, and a film can be formed at a high temperature. To manufacture a magnetic recording medium substrate from such a brittle material,
If a plate-shaped base material is made and then cut into a predetermined shape, it can be manufactured at low cost. In particular, when a plate-shaped base material is manufactured by slicing from a large ingot such as single crystal silicon, warpage can be reduced by cutting out from a plate-shaped base material larger than the target magnetic recording medium substrate. (See JP-A-6-76282).

[0004]

As such a cutting method, mechanical cutting is performed using fixed abrasive grains, loose abrasive grains, etc. Among them, a cup type core drill is used. (Refer to Japanese Patent No. 2564223), which is simple and convenient for producing a disk-shaped or donut-shaped magnetic recording medium substrate. An example of this cutting method is shown in FIGS. FIG. 3A is a schematic cross-sectional view when cutting the inner diameter of a donut shape, and FIG. 3B is a schematic cross-sectional view when cutting the outer diameter of a disk or donut shape.
Reference numeral 11 denotes a base material of the magnetic recording medium substrate, 12 denotes a vacuum suction table which is a jig for fixing the base material, and 13 denotes a cup-type core drill.

[0005] However, brittle materials are liable to crack, resulting in low yield. In addition, a flaky chip (hereinafter referred to as chipping) generated in a cut portion of a substrate surface is likely to occur, and large chipping is likely to occur particularly on a side where a cup-shaped core drill is removed. It is necessary to increase the amount of allowance in the follow-up processing after cutting in anticipation of the cut. In order to perform cutting with high accuracy and with suppressed occurrence of chipping, a base material may be attached to a carbon plate or the like, and cutting may be performed. However, there has been a problem that the cost increases. Also, when cutting out from a large base material, cutting out a plurality of sheets has the advantage of increasing the material yield. However, when cutting out a plurality of sheets, the chip (cutting base material) is reduced in chipping and deformation, and the cutting edge is reduced. In order to prevent the tool from being deformed and to be deformed, it was necessary to process the workpieces to be cut out somewhat apart. For this reason, there was a problem that the material yield was poor. Furthermore, if vacuum suction is used to fix the base material to the fixing jig, the area cut out during cutting is particularly small because the suction area of the part cut out when manufacturing a small magnetic recording medium substrate is small. There was a problem that the base material of the magnetic recording medium substrate or the cut work was chipped, cracked, or penetrated into the core drill, causing the yield and productivity to drop. .

[0006]

Means for Solving the Problems The present inventors have made intensive studies in view of the above problems and completed the present invention.
That is, the present invention relates to a method for manufacturing a magnetic recording medium substrate in which a donut-shaped or disk-shaped magnetic recording medium substrate is cut out from a plate-shaped base material having a diameter larger than the diameter of the substrate, wherein the base material is made of a brittle material. And fixing a groove having a width corresponding to a width obtained by adding 0 to 5 times the thickness of the base material to the cut-out portion of the base material to a fixing jig formed in advance, and cutting out using a cup-type core drill. It is.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. The plate-shaped base material of the magnetic recording medium substrate in the present invention is glass, oxide, nitride, carbide ceramics,
It is a brittle material such as sapphire or single-crystal silicon, preferably glass, sapphire, or single-crystal silicon. Among them, single-crystal silicon is more preferable because chipping is greatly reduced.

As shown in FIG. 1, a cup-shaped core drill used in the manufacturing method of the present invention has a base material 1 for a magnetic recording medium substrate.
Cylindrical portion 16 that cuts by contact with the top plate portion 1
5, further having a shank portion 14 on the top plate coaxially with the cylindrical portion for cutting the base material. Fix the shank to the rotating shaft of the motor (not shown)
While rotating the drill around the circular symmetry axis of the cylindrical portion of, the drill is pressed against the base material 1 and the base material is cut into a donut shape or a disk shape. The portion for cutting the base material of the cup-type core drill may use fixed abrasives in which hard abrasive particles such as diamond particles are fixed to the base material of the cup-type core drill by metal bond, resin bond, electrodeposition, or the like. Alternatively, cup-shaped core drills without abrasive grains may be rotated and cut out using free abrasive grains such as alumina, silicon carbide, and diamond while supplying these free abrasive grains to a processing position. The particle size of the abrasive used here may be 100 to 1000 mesh. In addition, in the part that comes into contact with the base material of the cup-shaped core drill, cutting chips are easily discharged from the cutting surface.
Also, a cut may be made so that the coolant for cooling the cut surface or discharging the cut waste from the cut surface is sufficiently spread over the cut surface. If the thickness of the cup-type core drill is too thin, it will deform and wear the blade more,
If the thickness is too large, the processing loss increases, so the thickness may be about 0.05 to 30 mm.

For supporting and fixing the base material of the magnetic recording medium substrate to the fixing jig 2, means such as vacuum suction and mechanical clamping are used without using an adhesive. By forming grooves 4 in the cut-out portion of the base material in advance in these base material fixing jigs, the base material fixing jig 2 can be used repeatedly, thereby improving productivity and further chipping the base material 1. Can be reduced.

The width of the groove 4 must be equal to or greater than the blade thickness of the cup-shaped core drill and equal to or smaller than the blade thickness plus five times the thickness of the substrate (base material). It is equal to or less than the width obtained by adding three times the thickness of. The chipping can be reduced as the groove width is closer to the drill blade thickness, but the drill blade does not enter the groove below the above range, and the base material or cut out of the magnetic recording medium substrate above the above range. This causes chipping, cracking, and cracking of the work, resulting in reduced yield and reduced strength of the manufactured magnetic recording medium. However, when cutting out a plastic material such as aluminum, if such a groove is formed in the base material fixing jig, a large burr will be formed on the drilling side of the substrate or the shape will be distorted. FIG. 2A is a top view of a base material fixing jig when two donut-shaped magnetic recording medium substrates are cut out.
Reference numeral 4a denotes a donut-shaped groove for an outer diameter, and 4b denotes a groove for an inner diameter.
The base material fixing jig may be provided with depressions, marks, pins, etc. for determining the position 5 of the base material as shown in FIG.

Materials for the base material fixing jig include synthetic resins such as acrylic, vinyl chloride, polyacetal, polycarbonate, and polypropylene; metals such as aluminum, stainless steel, brass, and copper; aluminum oxide, zirconia oxide;
Ceramics such as silicon nitride and graphite carbon can be used.

When manufacturing a doughnut-shaped magnetic recording medium substrate, the cut hole and the portion corresponding to the outer periphery of the cut work may be cut out simultaneously or separately. At the same time, a cup-shaped core drill having a cylindrical blade and coaxially disposed may be used. Cutting at the same time enables processing in a shorter time, but there are problems in that coolant is less likely to be applied and the shape of the cup-type core drill becomes complicated.

FIG. 2 (b) is a longitudinal sectional view of a donut-shaped magnetic recording medium substrate on which a base material having a middle hole is mechanically clamped. When the inner hole and the outer peripheral portion are separately cut out and mechanically clamped, first, a hole corresponding to the inner hole of the donut-shaped magnetic recording medium substrate of the base material 1 is made, and for example, as shown in FIG. After the clamp ring 8 is fixed to the intermediate hole and the screw hole 6 with the screw 7 and the base material 1 is pressed and fixed on the base material fixing jig 2, it corresponds to the outer peripheral portion of the donut-shaped magnetic recording medium substrate. You only have to cut out the part. Although the whole base material can be fixed by vacuum suction, if the work to be cut out is reduced in size, the suction area of the cut out part is small, so the cut out part comes off the base material fixing jig during cutting, The base material of the recording medium substrate or the cut work may be chipped, cracked, or penetrated into the cup-shaped core drill, causing a reduction in yield and productivity.

Further, according to the present invention, when cutting out a plurality of magnetic recording medium substrates, the cutting margin can be partially overlapped, thereby improving the material yield. In this case, for example, a base material fixing jig in which grooves are partially overlapped as shown in FIG. 2 may be used. In general, when cutting a plurality of pieces, it is necessary to work the workpieces somewhat apart in order to reduce chipping and deformation of the work and to prevent chipping and deformation of the blade. However, according to the present invention, even if a part of the cutting margin overlaps, the magnetic recording medium substrate can be cut out of the cup-shaped core drill serving as a cutting blade and the cut work without chipping or deformation.

[0015]

Next, examples of the present invention will be described. (Embodiment) As shown in FIG. 2A, a polyacetal base material fixing jig 2 in which grooves 4a and 4b having a groove width of 3.5 mm are formed in a portion where a drill hits and a screw hole 6 is formed in a position to be pressed by a screw is prepared. did. The two outer diameter grooves 4a were overlapped by 2.5 mm in width. A base material 1 of a magnetic recording medium substrate for a magnetic disk substrate made of single-crystal silicon having a diameter of 105 mm and a thickness of 0.6 mm is fixed to this base material fixing jig, and a 3 mm blade and a 12 mm outer diameter cup-shaped core drill is used. Disks were cut out at two places on the base metal so that the core drill blade was at the groove position. Then, as shown in FIG. 2B, a clamp ring 8 was fixed to the cut-out hole with a screw 7, and the base material 1 was pressed. After that, blade thickness 3mm, inner diameter
Using a 48 mm cup-type core drill, two donut-shaped disks having an outer diameter of 48 mm and an inner diameter of 12 mm, each of which has a cutting margin of 3 mm partially overlapping each other, so that the blade of the core drill comes to the groove position, were cut out. After producing 100 discs, the size of chipping was measured with an optical microscope, and the discs produced were classified according to the largest chipping, as shown in Table 1. In addition, when the roundness of a disk was randomly extracted and measured for 20 sheets, 10
There was no deformation below μm and the shape was good.

Comparative Example As shown in FIG. 3A, a conventionally known polyacetal base material fixing jig 12 was prepared. Diameter 66
A base material 11 of a magnetic recording medium substrate for a magnetic disk substrate made of single-crystal silicon having a thickness of 0.6 mm and a thickness of 0.6 mm is fixed thereto by a vacuum chuck, and a cup-shaped core drill 13 having a blade thickness of 3 mm and an outer diameter of 12 mm.
, One disk was cut out of the base material. Thereafter, as shown in FIG. 3B, a donut-shaped disk having an outer diameter of 48 mm and an inner diameter of 12 mm was produced using a cup-shaped core drill 13 having a blade thickness of 3 mm and an inner diameter of 48 mm. After producing 100 discs, the results of classification by measuring the size of chipping with an optical microscope in the same manner as in the examples are also shown in Table 1. Further, the circularity of the disc was measured in the same manner as in the example, and as a result, some of the discs were bad and exceeded 50 μm.

[0017]

[Table 1]

From Table 1, it can be seen that the example can reduce chipping as compared with the comparative example. In addition, despite the cut-out allowance overlapping the adjacent disk, the donut-shaped disk manufactured in the example had a roundness of 10 μm or less, which was not deformed, and had a good shape.

[0019]

According to the present invention, chipping and cracking in cutting out the magnetic recording medium substrate can be reduced without bonding the base material to the fixing jig, and therefore, the production cost of the substrate can be reduced. The material yield can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a method for manufacturing a magnetic recording medium substrate according to the present invention.

FIG. 2 is a schematic view of an embodiment of the present invention. (A) is a top view of a base material fixing jig. (B) is sectional drawing which clamps the base material which bored the inside hole.

FIG. 3 is a schematic view of an example of a conventional method for manufacturing a magnetic recording medium substrate. (A) is a sectional view at the time of cutting the inner diameter,
(B) is a sectional view at the time of cutting the outer diameter.

[Explanation of symbols]

 1, 11 {base material of magnetic recording medium substrate 2} base material fixing jig 3, 13} cup-shaped core drill 4 {groove 4a} outer diameter groove 4b}溝 Inner groove 5 ‥‥‥‥ Base material position 6 ‥‥‥‥ Screw hole 7 ‥‥‥‥ Screw 8 ‥‥‥‥ Clamp ring 12 ‥‥‥‥ Vacuum suction table 14, 24 ‥‥ Shank of drill Top plate part of 15,25 部分 drill Cylindrical part of 16,26 ‥‥ drill

Claims (5)

[Claims] 1. A method for manufacturing a magnetic recording medium substrate, wherein a donut-shaped or disk-shaped magnetic recording medium substrate is cut out from a plate-shaped base material having a diameter larger than the diameter of the substrate, wherein the base material is made of a brittle material. A groove having a width corresponding to a width obtained by adding 0 to 5 times the thickness of the base material to the cutout portion of the base material is fixed to a pre-formed fixing jig, and cut out using a cup-type core drill. A method for manufacturing a magnetic recording medium substrate. 2. A method for manufacturing a magnetic recording medium substrate, wherein a plurality of donut-shaped or disk-shaped magnetic recording medium substrates are cut out from a plate-shaped base material having a diameter larger than the diameter of the substrate. A method for manufacturing a magnetic recording medium substrate comprising a brittle material, wherein the cutting margins are partially overlapped, and the cutting is performed using a cup-shaped core drill. 3. The base material is cut out by fixing a groove having a width equivalent to a width obtained by adding 0 to 5 times the thickness of the base material to a cut-out portion of the base material in a pre-formed fixing jig. A method for manufacturing a magnetic recording medium substrate according to claim 2. 4. A method of manufacturing a donut-shaped magnetic recording medium substrate by cutting out a donut-shaped magnetic recording medium substrate from a plate-shaped base material having a diameter larger than the diameter of the substrate. A method for manufacturing a magnetic recording medium substrate, comprising: forming a hole in a portion corresponding to a medium hole; fixing a base material with the medium hole; and cutting out a portion corresponding to an outer peripheral portion of the donut-shaped magnetic recording medium substrate. 5. The base material is single crystal silicon.
The method for manufacturing a magnetic recording medium substrate according to any one of the above.