JP3172107B2 - Method for manufacturing glass substrate for information recording medium and method for manufacturing information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium used as a recording medium of an information processing apparatus, a method of manufacturing an information recording medium using the substrate, and the like.

[0002]

2. Description of the Related Art A magnetic disk is one of such information recording media. A magnetic disk is formed by forming a thin film such as a magnetic layer on a substrate, and an aluminum or glass substrate has been used as the substrate. However, in recent years, in response to the pursuit of higher recording density, the proportion of the glass substrate that can make the distance between the magnetic head and the magnetic recording medium smaller than that of aluminum has been gradually increasing. The glass substrate, which tends to increase in this manner, is generally manufactured by chemically strengthening it to increase the strength so as to withstand the impact when mounted on a magnetic disk driver. In addition, the glass substrate surface is polished with high precision to achieve a high recording density so that the flying height of the magnetic head can be reduced as much as possible.

On the other hand, not only the glass substrate but also the magnetic head changes from a thin film head to a magnetic resistance (MR head).
Responding to high recording density.

[0004]

As described above, high flatness of the surface of a magnetic disk is indispensable for a low flying height required for a high recording density. In addition, when an MR head is used, a high flatness is required on the surface of the magnetic recording medium due to the problem of TA (thermal asperity). The thermal asperity is such that when a protrusion is present on the surface of a magnetic disk, the protrusion is affected by the MR head, and heat is generated in the MR head. This is a phenomenon that causes malfunction.

As described above, the demand for high flatness of the surface of the magnetic disk has been increasing day by day to reduce the flying height and to prevent the occurrence of thermal asperity. In order to obtain such high flatness of the magnetic disk surface, a substrate surface with high flatness is ultimately required. However, if the substrate surface is no longer polished with high precision, the high recording density of the magnetic disk can no longer be obtained. We have reached the stage where we cannot realize the realization. In other words, no matter how high the polishing accuracy, high flatness cannot be obtained if foreign matter adheres to the substrate. Of course, foreign matter has been conventionally removed, but foreign matter on the substrate, which has been conventionally allowed, is considered to be a problem at today's high-density level.

[0006] Examples of this kind of foreign matter include extremely fine iron powder which cannot be removed by ordinary washing. When a thin film such as a magnetic film is laminated with the iron powder adhered to the glass substrate, a protrusion is formed on the surface of the magnetic disk, which causes a reduction in flying height and prevention of thermal asperity. . An object of the present invention is to prevent such a small piece of metal such as iron powder from adhering to a glass substrate.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned object, and has ascertained the cause of the adhesion of fine iron powder to a glass substrate. A metal or metal oxide such as iron powder is directly or chemically treated on a glass substrate from a chemical strengthening treatment tank containing a treating solution or a holding means for holding the glass substrate when the glass substrate is immersed in the chemical strengthening treating solution. It was found to adhere indirectly through the liquid. In particular, since the chemical strengthening treatment is performed at a high temperature (for example, 350 to 450 degrees), it has been found that a chemically strengthened glass substrate having a clean surface cannot be obtained unless a specific stainless steel alloy is used.

According to a first configuration of the present invention, the glass substrate held by the holding means is brought into contact with a chemical strengthening treatment liquid, so that some of the ions contained in the glass substrate have an ion diameter larger than the ions. In the method for manufacturing a glass substrate for an information recording medium, the method includes a chemical strengthening step of strengthening the glass substrate by substituting the glass substrate with ions in the processing solution of (1). A method for manufacturing a glass substrate for an information recording medium, wherein the holding means for holding the wall surface and / or the glass substrate is made of a stainless steel alloy having corrosion resistance in a high temperature range of the heating temperature of the chemical strengthening treatment liquid.

According to a second configuration of the present invention, the glass substrate held by the holding means is brought into contact with a chemical strengthening treatment liquid to convert some of the ions contained in the glass substrate into an ion having a larger ion diameter than the ions. In the method for manufacturing a glass substrate for an information recording medium, the method includes a chemical strengthening step of strengthening the glass substrate by substituting the glass substrate with ions in the processing solution of (1). A method for manufacturing a glass substrate for an information recording medium, wherein the holding means for holding the wall surface and / or the glass substrate is made of a martensitic or austenitic stainless steel alloy.

A third aspect of the present invention is the method of manufacturing a glass substrate for an information recording medium according to the first or second aspect, wherein the glass substrate for the information recording medium is a glass substrate for a magnetic disk. A fourth aspect of the present invention is the method for manufacturing a glass substrate for an information recording medium according to the third aspect, wherein the glass substrate for the information recording medium is a glass substrate for a magnetoresistive head.

According to a fifth aspect of the present invention, there is provided an information recording medium wherein at least a recording layer is formed on a glass substrate obtained by the method for producing a glass substrate for an information recording medium according to any one of the first to fourth aspects. Manufacturing method.

According to a sixth aspect of the present invention, in the method for manufacturing an information recording medium according to the fifth aspect, the recording layer is a magnetic layer.

Various means are conceivable as means for holding the glass substrate. In short, it is preferable that the chemical strengthening treatment liquid can come into contact with the glass substrate in a predetermined state and does not cause liquid dripping. . The martensitic or austenitic stainless alloy is preferably provided by both the chemical strengthening bath and the means for holding the glass substrate, but either one may be used. Further, it is preferable that the whole of the chemical strengthening tank or the glass substrate holding means is made of a martensitic or austenitic stainless steel alloy, but only a portion that comes into contact with the chemical strengthening treatment liquid may be used. These martensitic or austenitic stainless alloys have excellent corrosion resistance in a high temperature range, so that dust of metal pieces can be prevented.

The heating temperature of the chemical strengthening treatment liquid is 200 to 50.
Around 0 ° C is planned.

The type, size, thickness and the like of the glass substrate are not particularly limited. Examples of the material of the glass substrate include aluminosilicate glass, soda lime glass, soda aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, quartz glass, chain silicate glass, and glass ceramics such as crystallized glass. Can be

As the aluminosilicate glass, Si
O ₂ : 62 to 75% by weight, Al ₂ O ₃ : 5 to 15% by weight,
Li ₂ O: 4 to 10% by weight, Na ₂ O: 4 to 12% by weight,
ZrO _2: 5.5 to 15 with containing by weight% as the main component, the weight ratio of Na ₂ O / ZrO ₂ is 0.5 to 2.
0, Al ₂ O ₃ / weight ratio of ZrO ₂ of glass for chemical strengthening is 0.4 to 2.5 is preferred. In order to eliminate projections on the glass substrate surface caused by undissolved ZrO ₂ , 57% to 74% of SiO ₂ , Zn
O ₂ and 0 to 2.8%, the Al ₂ O ₃ 3 to 15% of LiO ₂ 7 to 16% it is preferred to use chemical strengthening glass containing Na ₂ O 4~14%. The aluminosilicate glass or the like having such a composition increases the transverse rupture strength by chemical strengthening, has a deep compressive stress layer, and is excellent in Knoop hardness.

In the present invention, the surface of the glass substrate is subjected to a chemical strengthening treatment by a low-temperature ion exchange method for the purpose of improving impact resistance, vibration resistance and the like.

Here, the chemical strengthening method is not particularly limited as long as it is a conventionally known chemical strengthening method. For example, a low-temperature type chemical strengthening method in which ion exchange is performed in a region not exceeding a transition temperature from the viewpoint of a glass transition point. Are preferred. Potassium nitrate,
Examples thereof include sodium nitrate, and a nitrate obtained by mixing them.

The glass substrate for an information recording medium according to the manufacturing method of the present invention can be used as a glass substrate for a magnetic recording medium, a glass substrate for a magneto-optical disk, and a disk substrate for an electro-optical disk such as an optical disk. In particular, the present invention can be suitably applied to a magnetic disk substrate for a magnetoresistive head for recording and reproducing with a magnetoresistive head (including a large-sized magnetoresistive head) and a method for manufacturing an information recording medium using the same.

Next, the magnetic recording medium of the present invention will be described.

The magnetic recording medium of the present invention is obtained by forming at least a magnetic layer on the glass substrate for a magnetic recording medium of the present invention.

In the present invention, since particles which cause thermal asperity or head crash are not generated, a magnetic layer or the like is formed on a glass substrate to manufacture a magnetic recording medium. There is no protrusion formed on the main surface by particles that cause thermal asperity, and head crash can be prevented at a higher level. In particular, the function of the magnetoresistive head can be fully exploited for a magnetic recording medium that performs reproduction with the magnetoresistive head. Further, C which can be suitably used for a magnetoresistive head can be used.
The performance of a magnetic recording medium such as an oPt system can be sufficiently brought out.

Similarly, on the recording / reproducing surface of the magnetic recording medium, there is no projection formed by particles that cause thermal asperity, and a head crash can be prevented at a higher level.

Further, there is no possibility that a particle such as a thermal asperity causes a defect in a film such as a magnetic layer to cause an error.

A magnetic recording medium usually has a predetermined flatness and surface roughness, and is provided with an underlayer, a magnetic layer, a protective layer, It is manufactured by sequentially laminating a lubricating layer.

The underlayer in the magnetic recording medium of the present invention comprises:
It is selected according to the magnetic layer.

As the underlayer, for example, Cr, Mo, T
a, an underlayer made of at least one material selected from nonmagnetic metals such as Ti, W, V, B, and Al. In the case of a magnetic layer containing Co as a main component, it is preferable to use Cr alone or a Cr alloy from the viewpoint of improving magnetic properties. The underlayer is not limited to a single layer, and may have a multilayer structure in which the same or different layers are stacked. For example, Cr / Cr, Cr / CrMo, Cr / CrV, Cr
V / CrV, Al / Cr / CrMo, Al / Cr / C
r, a multilayer base layer of Al / Cr / CrV, Al / CrV / CrV and the like.

The material of the magnetic layer in the magnetic recording medium of the present invention is not particularly limited.

As the magnetic layer, for example, CoPt, CoCr, CoNi, CoNiCr, C
oCrTa, CoPtCr, CoNiPt, CoNi
CrPt, CoNiCrTa, CoCrTaPt, Co
A magnetic thin film such as CrPtSiO may be used. The magnetic layer is made of a non-magnetic film (for example, Cr, CrMo, Cr).
V, etc. to reduce noise (for example, CoPtCr / CrMo / CoPtCr, CoC
rTaPt / CrMo / CoCrTaPt).

As a magnetic layer corresponding to a magnetoresistive head (MR head) or a large magnetoresistive head (GMR head), Y, Si, rare earth elements, Hf, G
An impurity element selected from e, Sn, and Zn, or an element containing an oxide of these impurity elements is also included.

As the magnetic layer, in addition to the above, magnetic particles such as Fe, Co, FeCo, and CoNiPt are dispersed in a non-magnetic film made of ferrite, iron-rare earth, SiO ₂ , BN, or the like. It may be a granular structure or the like. Further, the magnetic layer may have any of an inner surface type and a perpendicular type recording format.

The protective layer in the magnetic recording medium of the present invention is not particularly limited.

Examples of the protective layer include a Cr film, a Cr alloy film, a carbon film, a zirconia film, and a silica film. These protective films can be continuously formed with an underlayer, a magnetic layer, and the like by an in-line type sputtering apparatus. Also,
These protective films may have a single-layer structure or a multilayer structure composed of the same or different films.

In the present invention, another protective layer may be formed on the protective layer or in place of the protective layer. For example, instead of the above-mentioned protective layer, colloidal silica fine particles are dispersed and applied to a Cr film after diluting tetraalkoxylan with an alcohol-based solvent, and then fired to form a silicon oxide (SiO ₂ ) film. It may be formed.

The lubricating layer in the magnetic recording medium of the present invention is not particularly limited.

The lubricating layer is prepared, for example, by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a solvent such as Freon, and applying the diluent to the medium surface by dipping, spin coating, or spraying. It is formed by performing heat treatment.

[0037]

EXAMPLES The present invention will be described below more specifically based on examples.

Embodiment 1

(1) Roughing Step First, a glass substrate made of an aluminosilicate glass having a diameter of 96 mmφ and a thickness of 3 mm cut out from a sheet glass formed by a down-draw method with a grinding wheel is used.
Grinding with a relatively rough diamond wheel
It was molded to a diameter of 1.5 mm and a thickness of 1.5 mm. In this case, instead of the downdraw method, the molten glass may be directly pressed using an upper mold, a lower mold, and a body mold to obtain a disk-shaped glass body. Further, it may be formed by a float method.

As the aluminosilicate glass, in terms of mol%, SiO ₂ is 57 to 74%, ZnO ₂ is 0 to 2.8%, Al ₂ O ₃ is ₃ to 15%, and LiO ₂ is 7 to 74%.
Glass for chemical strengthening containing 16% and 4 to 14% of Na ₂ O as main components (for example, Si
O ₂ : 67.0%, ZnO ₂ : 1.0%, Al ₂ O ₃ : 9.
Glass for chemical strengthening containing 0%, LiO ₂ : 12.0%, and Na ₂ O: 10.0% as main components) was used.

Next, both surfaces of the glass substrate were ground one by one with a diamond grindstone having a finer grain size than the grindstone. The load at this time was about 100 kg. As a result, the surface roughness of both surfaces of the glass substrate can be reduced to Rmax (JIS
B 0601) (about 10 μm).

Next, a hole is made in the center of the glass substrate using a cylindrical grindstone, and the outer peripheral end surface is also ground to a diameter of 95 mmφ. Then, the outer peripheral end surface and the inner peripheral surface are subjected to predetermined chamfering. did. At this time, the surface roughness of the end face of the glass substrate was about 4 μm in Rmax.

(2) Mirror Processing of End Surface Next, the surface roughness of the end surface of the glass substrate is set to 1 μm in Rmax while rotating the glass substrate by brush polishing.
Polished to about 0.3 μm with Ra.

The surface of the glass substrate which had been subjected to the above-mentioned mirror polishing of the end face was washed with water.

(3) Sanding (Wrapping) Step Next, the glass substrate was sanded. This sanding step aims at improving dimensional accuracy and shape accuracy.
The sanding process was performed using a lapping device, and was performed twice while changing the grain size of the abrasive grains to # 400 and # 1000.

More specifically, first, a load L was set to about 100 kg using alumina abrasive grains having a grain size of # 400.
By rotating the internal rotation gear and the external rotation gear, both sides of the glass substrate housed in the carrier are surface-accurate 0-1 μm,
Lapping was performed to a surface roughness (Rmax) of about 6 μm.

Next, the particle size of the alumina abrasive grains was changed to # 1000.
Perform lapping instead of surface roughness (Rmax) 2μ
m.

The glass substrate that had been subjected to the above sanding process was washed by sequentially immersing it in a washing tank of a neutral detergent and water.

(4) First Polishing Step Next, a first polishing step was performed. This first polishing step is intended to remove scratches and distortion remaining in the above sanding step, and was performed using a polishing apparatus.

More specifically, the first polishing step was performed under the following polishing conditions using a hard polisher (cerium pad MHC15: manufactured by Speed Fam) as a polisher (polishing powder).

Polishing liquid: cerium oxide + water Load: 300 g / cm ² (L = 238 kg) Polishing time: 15 minutes Removal amount: 30 μm Lower platen rotation speed: 40 rpm Upper platen rotation speed: 35 rpm Gear rotation speed in the inner part: 14 rpm Outer gear rotation speed: 29 rpm

The glass substrate after the first polishing step is
Immerse in each washing tank of neutral detergent, pure water, pure water, IPA (isopropyl alcohol), IPA (steam drying) sequentially,
Washed.

(5) Second Polishing Step Next, using the polishing apparatus used in the first polishing step, the polisher was changed from a hard polisher to a soft polisher (Polyak: manufactured by Speed Fam), and the second polishing step was performed. Carried out. The polishing conditions were the same as in the first polishing step, except that the load was 100 g / cm ² , the polishing time was 5 minutes, and the removal amount was 5 μm.

The glass substrate after the second polishing step is
Washing was performed by sequentially immersing in a washing tank of a neutral detergent, a neutral detergent, pure water, pure water, IPA (isopropyl alcohol), and IPA (steam drying). In addition, ultrasonic waves were applied to each cleaning tank.

(6) Chemical Strengthening Step Next, the glass substrate after the grinding, polishing and cleaning steps was chemically strengthened. The chemical strengthening is performed by putting the chemical strengthening treatment liquid into the chemical strengthening treatment tank and immersing the glass substrate held by the holding member in the chemical strengthening treatment liquid. In addition, the holding member of the glass substrate is formed by connecting three pillars having a plurality of V-grooves formed at equal intervals in the arrangement direction of the glass substrates by connecting members at both end surfaces thereof. The plurality of glass substrates are supported and held at three points by V-grooves in the same plane of the three columns, and are arranged in the direction in which the columns extend.

Each support and connecting member of the holding member of this embodiment is made of SUS316, which is an austenitic stainless steel alloy having excellent corrosion resistance in a high temperature range. The chemical strengthening treatment tank is made of austenitic stainless alloy SUS3.
04. The materials of the chemical strengthening treatment tank and the holding means may be the same or different. As another stainless steel alloy, for example, SUS316L is suitable. A specific method of chemical strengthening is to prepare a chemical strengthening solution in which potassium nitrate (60%) and sodium nitrate (40%) are mixed, and heat the chemical strengthening solution to 400 ° C., and wash the pre-heated 300 ° C. The glass substrate was immersed for about 3 hours.
At the time of this immersion, in order to chemically strengthen the entire surface of the glass substrate, a plurality of glass substrates were held by holding members so as to be held at end faces.

As described above, by performing the immersion treatment in the chemical strengthening solution, the lithium ions and the sodium ions on the surface layer of the glass substrate become the sodium ions and the sodium ions in the chemical strengthening solution.
The glass substrate is strengthened by being respectively substituted by potassium ions.

The thickness of the compressive stress layer formed on the surface of the glass substrate was about 100 to 200 μm. In addition, during chemical strengthening, the chemical strengthening treatment tank and the holding member for the glass substrate that are in contact with the high-temperature chemical strengthening treatment solution are made of an austenitic stainless steel alloy with excellent chemical durability. Thus, it was possible to prevent metal pieces such as chromium and metal oxides from adhering to the glass substrate.

The glass substrate which has been chemically strengthened is
It was immersed in a water bath at a temperature of 10 ° C., rapidly cooled, and maintained for about 10 minutes.

The quenched glass substrate is heated to about 40 ° C.
The substrate was immersed in heated sulfuric acid and washed while applying ultrasonic waves.

The surface roughness Ra of the main surface of the glass substrate obtained through the above steps was 0.5 to 1 nm. Further, upon close inspection of the glass surface, no particles causing thermal asperity were found. In particular, no fine iron powder of 3 to 5 microns or more was observed at all.

(7) Magnetic Disk Manufacturing Process A texture layer, a Cr underlayer, and a CrMo underlayer are formed on both surfaces of the magnetic disk glass substrate obtained through the above-described steps by using an in-line type sputtering apparatus by sputtering AlN. , A CoPtCrTa magnetic layer and a C protective layer were sequentially formed to obtain a magnetic disk.

A glide test was performed on the obtained magnetic disk. As a result, no hit (the head touches a protrusion on the surface of the magnetic disk) or crash (the head collides with the protrusion on the surface of the magnetic disk) was not recognized. . In addition, it was confirmed that no defect was generated in the film such as the magnetic layer due to the particles causing the thermal asperity.

The embodiment in which the tank and the holding member that come into contact with the chemical strengthening treatment liquid are made of a stainless steel having high corrosion resistance as in the present invention, and the stainless steel whose corrosion resistance is not so high like SUS430 (ferritic stainless alloy). When a comparison was made between the alloy and the comparative example in which the holding member and the tank were formed, in the comparative example, many fine iron powders of 10 μm to 80 μm were found on the surface of the glass substrate. As described above, in this example, the amount of foreign matters such as iron was significantly reduced.

A reproduction test was performed on the magnetic disk of this embodiment after the glide test with a magnetoresistive head. However, a malfunction of reproduction due to thermal asperity was observed for all of a plurality of samples (500 sheets). I was not able to admit.

[0066] soda-lime glass in place of Examples 2-3 aluminosilicate glass (Example 2), except for the use of soda aluminosilicate glass (Example 3) in the same manner as in Example 1, a glass for a magnetic disk A substrate and a magnetic disk were obtained.

As a result, similarly to Example 1, a chemically strengthened glass having no metal pieces such as iron powder on the surface was obtained.

Next, the same glass type glass substrate as in Examples 1 to 3 was chemically strengthened by changing the material of the chemical strengthening tank and the holding member from an austenitic stainless alloy to a martensitic stainless alloy. The same effect as in the case of the stainless alloy was obtained.

Example 4 Al (50 angstrom film thickness) / Cr (100
0 Å / CrMo (100 Å), CoPtCr (120 Å) / CrMo (50 Å) / Co
A magnetic layer made of PtCr (120 Å),
A Cr (50 Å) protective layer was formed by an in-line type sputtering apparatus.

The above substrate is immersed in an organic silicon compound solution (a mixed solution of water, IPA and tetraethoxysilane) in which fine silica particles (particle size: 100 Å) are dispersed,
A protective layer having a texture function made of SiO ₂ is formed by firing, and a dip treatment is performed on the protective layer with a lubricant made of perfluoropolyether to form a lubricating layer. Got a disc.

When a glide test was conducted on the obtained magnetic disk, no hit or crash was recognized. It was also confirmed that no defect occurred in the film such as the magnetic layer. Furthermore, as a result of a reproduction test using a magnetoresistive head, no reproduction malfunction due to thermal asperity was recognized.

Example 5 The underlayer was made of Al / Cr / Cr, and the magnetic layer was made of CoNiCr.
A magnetic disk for a thin film head was obtained in the same manner as in Example 4 except that Ta was used.

The same thing as Example 4 was confirmed for the above magnetic disk.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments.

For example, the type of the glass substrate and the type of the magnetic layer are not limited to those of the embodiment.

[0076]

As described above, according to the present invention, since particles such as metal or metal oxide do not adhere to the glass substrate, particles which cause head crash or thermal asperity may be generated. In addition, it is possible to prevent the reproduction function from deteriorating due to thermal asperity.

Further, it is possible to avoid defects caused by particles that cause thermal asperity, and to obtain a higher quality magnetic recording medium with a higher yield.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 5/84 B01J 19/00 C03C 21/00 C22C 38/00

Claims (7)

(57) [Claims] 1. By contacting a glass substrate held by a holding means with a chemical strengthening treatment liquid, some ions contained in the glass substrate are converted into ions in the treatment liquid having an ion diameter larger than that of the glass substrate. Magnetic head for magnetoresistive head including chemical strengthening process to strengthen glass substrate by replacement
In a method for manufacturing a disk substrate for a disk , at least a wall surface of a chemical strengthening treatment tank containing the chemical strengthening treatment solution and / or a holding means for holding the glass substrate is held in a high temperature range of a heating temperature of the chemical strengthening treatment solution. In gold
A magnetic disk for a magnetoresistive head , comprising a corrosion-resistant stainless steel alloy capable of preventing dust generation of metal fragments.
A method of manufacturing a glass substrate for a disc . 2. A method in which a glass substrate held by a holding means is brought into contact with a chemical strengthening treatment liquid to convert some of the ions contained in the glass substrate into ions in the treatment liquid having an ion diameter larger than that of the glass substrate. In the method for manufacturing a magnetic disk glass substrate for a magnetoresistive head including a chemical strengthening step of strengthening the glass substrate by replacing, the number of chemical strengthening treatment tanks containing the chemical strengthening treatment liquid is reduced.
Hold the wall and / or glass substrate in contact with the processing liquid
The holding means in the high temperature range of the heating temperature of the chemical strengthening treatment liquid.
Corrosion-resistant stainless steel alloy that can prevent dust generation from metal fragments
Stainless steel excluding ferritic stainless steel alloy
Magnetic material for a magnetoresistive head, comprising a magnetic alloy
A method for manufacturing a glass substrate for a gas disk . 3. A glass substrate held by a holding means is brought into contact with a chemical strengthening treatment liquid to convert some of the ions contained in the glass substrate into ions in the treatment liquid having an ion diameter larger than that of the glass substrate. In the method for manufacturing a magnetic disk glass substrate for a magnetoresistive head including a chemical strengthening step of strengthening the glass substrate by replacing, the number of chemical strengthening treatment tanks containing the chemical strengthening treatment liquid is reduced.
Holds both the wall surface and the glass substrate in contact with the processing liquid
The means must be used to remove metal fragments in the high
Constructed of corrosion-resistant stainless steel alloy that can prevent dust generation
For magnetic disks for magnetoresistive heads
A method for manufacturing a glass substrate . 4. By contacting the glass substrate held by the holding means with the chemical strengthening treatment liquid, some ions contained in the glass substrate are converted into ions in the treatment liquid having an ion diameter larger than that of the glass substrate. Magnetic head for magnetoresistive head including chemical strengthening process to strengthen glass substrate by replacement
In the method of manufacturing a glass substrate for a disc, the holding means for holding at least the wall surface and / or the glass substrate of the chemical strengthening treatment tank that accommodates the chemical strengthening treatment solution and / or the glass substrate is made of a martensitic or austenitic stainless alloy. Magnetic resistor
A method of manufacturing a glass substrate for a magnetic disk for an anti-head . 5. By contacting the glass substrate held by the holding means with the chemical strengthening treatment solution, some ions contained in the glass substrate are converted into ions in the treatment solution having an ion diameter larger than the ions. In the method for manufacturing a magnetic disk glass substrate for a magnetoresistive head including a chemical strengthening step of strengthening the glass substrate by replacing, the number of chemical strengthening treatment tanks containing the chemical strengthening treatment liquid is reduced.
Holds both the wall surface and the glass substrate in contact with the processing liquid
The means should be a martensitic or austenitic stainless steel.
A magnetoresistive head characterized by being made of a stainless steel alloy.
Of manufacturing a glass substrate for a magnetic disk . 6. The magnetic disk for a magnetoresistive head according to claim 5, wherein the whole of the chemical strengthening treatment tank or the holding means for holding the glass substrate is made of a martensitic or austenitic stainless steel alloy. A method for manufacturing a glass substrate. 7. A method for manufacturing a magnetic disk for a magnetoresistive head, comprising forming at least a magnetic layer on a glass substrate obtained by the method according to claim 1.