WO2012090377A1 - Procédé de fabrication de substrat en verre pour support d'enregistrement magnétique d'informations - Google Patents

Procédé de fabrication de substrat en verre pour support d'enregistrement magnétique d'informations Download PDF

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Publication number
WO2012090377A1
WO2012090377A1 PCT/JP2011/006481 JP2011006481W WO2012090377A1 WO 2012090377 A1 WO2012090377 A1 WO 2012090377A1 JP 2011006481 W JP2011006481 W JP 2011006481W WO 2012090377 A1 WO2012090377 A1 WO 2012090377A1
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Prior art keywords
glass
glass substrate
lapping
base plate
recording medium
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PCT/JP2011/006481
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English (en)
Japanese (ja)
Inventor
葉月 中江
河合　秀樹
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コニカミノルタオプト株式会社
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Priority to JP2012518332A priority Critical patent/JP5071603B2/ja
Publication of WO2012090377A1 publication Critical patent/WO2012090377A1/fr

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C19/00—Surface treatment of glass, not in the form of fibres or filaments, by mechanical means

Definitions

  • the present invention relates to a method for producing a glass substrate for a magnetic information recording medium.
  • a typical example of an information recording medium having a recording layer for recording information using properties such as magnetism, light, and magnetomagnetism is a magnetic disk.
  • a substrate for this magnetic disk an aluminum alloy substrate or glass substrate plated with nickel phosphorus is known.
  • the magnetic disk substrate is mounted on a hard disk drive, and the magnetic head is levitated at a constant height relative to the substrate surface while rotating the disk at a high speed to record and reproduce magnetic information. For this purpose, it is necessary to further reduce the flying height of the magnetic head. In this case, if there is a very small foreign object on the magnetic disk, the head and the disk collide.
  • a phenomenon called head crash occurs and the hard disk may become unusable. Even when the head does not crash, the flying stability of the head is affected, so that the glide characteristics (an index of how stably the head floats on the magnetic disk) may be deteriorated.
  • a molten glass is poured onto a molten metal, a glass base plate is produced in a sheet shape, and then cut into a required size, or a molten glass is directly processed into a predetermined size.
  • press molding There is a method of press molding.
  • a method of cutting out from a sheet-like glass plate is becoming mainstream. At this time, when a glass plate is cut out from the sheet material, it has been found that cracks are generated from the cut lines to be cut out.
  • the alkali component in the glass substrate is eluted from the crack portion, and the recording surface is contaminated. As a result, the eluted component collides with the head, and a head crash may occur.
  • a hard disk is used for in-vehicle use such as car navigation, its heat resistance has been strongly demanded. Therefore, when using a hard disk at a high temperature, the elution of the alkali component is particularly large, so the occurrence of a head crash due to this elution component becomes a habit and the presence of minute cracks has become unacceptable. .
  • Patent Document 1 As a method of reducing this crack, a manufacturing method has been reported in which a cut line is first inserted in an oblique direction, and the glass base plate is cut out from the cut line.
  • the DFH mechanism refers to a so-called ABS surface (air bearing surface, air bearing surface) by bringing only a head element that performs a recording / reproducing operation in a magnetic head close to the information recording medium when reading / writing information on the information recording medium.
  • a dynamic flying height control technology Dynamic Flying Height control technology, DFH control technology
  • the method for producing a glass substrate for a magnetic information recording medium includes a cutting step for cutting a glass material along one surface of the glass material, and a fixed abrasive containing diamond particles.
  • FIG. 1 is a partial cross-sectional perspective view showing a magnetic disk as an example of a magnetic recording medium using a glass substrate for magnetic information recording medium manufactured by the method for manufacturing a glass substrate for magnetic information recording medium according to the present embodiment.
  • the method for producing a glass substrate for a magnetic information recording medium includes a cutting step of cutting a glass material along one surface of a glass material, and cutting the glass material along the cutting material, and a fixed abrasive containing diamond particles.
  • a lapping step of grinding the surface of the glass base plate using an upper and lower surface plate provided on a grinding surface and a method for producing a glass substrate for a magnetic information recording medium, comprising: A surface with the cut line is disposed on the surface plate side, and a surface without the cut line is disposed on the lower surface plate side.
  • the manufacturing method of the glass substrate for magnetic information recording media is not particularly limited as long as it includes the cutting step and the lapping step.
  • a disk processing step including a cutting step to cut and cut a glass material sheet manufactured by the float process, and aligning the surface with the cut line placed on the upper surface plate of the grinding machine, There is no particular limitation except that the surface on which the cut lines are not placed is placed on the lower surface plate and each glass substrate is ground, and any conventionally known manufacturing method may be used.
  • Examples of the method for producing a glass substrate for a magnetic information recording medium include a disk processing step, a lapping step, a rough polishing step (primary polishing step), a cleaning step, a chemical strengthening step, a precision polishing step (secondary polishing step), and Examples include a method including a final cleaning step.
  • the steps may be performed in this order, or the order of the chemical strengthening step and the precision polishing step (secondary polishing step) may be switched.
  • a method including steps other than these may be used. For example, an end surface polishing step may be performed between the lapping step and the rough polishing step (primary polishing step).
  • a through-hole 10a is formed in the central portion from a glass base plate formed from a glass material having a predetermined composition so that the inner periphery and the outer periphery are concentric as shown in FIG.
  • This is a process of processing into a disk-shaped glass base plate 10. Specifically, for example, processing is performed as follows.
  • FIG. 2 is a cross-sectional view showing a process of cutting out a disk-shaped glass substrate according to the present invention.
  • the disk processing step includes a cutting step in which a cut line is made on one side of a glass material formed in a plate shape on a molten metal and cut along the cut line.
  • the cutting step after forming a cut line on the surface of the glass base plate that is in contact with the molten metal of the glass material, the cutting line is advanced in the thickness direction of the glass base plate to form a disk-shaped glass base plate. To cut out.
  • FIG. 2A is a cross-sectional view of the plate-like glass material 1.
  • a plate-shaped glass material manufactured by a float method is used as the glass material.
  • the float method is, for example, a method in which a molten liquid obtained by melting a glass material is poured onto molten tin and solidified as it is.
  • a free surface In the obtained glass base plate, one surface is a free surface of glass (hereinafter referred to as a free surface) and the other surface (hereinafter referred to as a contact surface) is an interface between glass and tin.
  • a free surface a free surface of glass
  • a contact surface is an interface between glass and tin.
  • the thickness a 0.95 mm thing is mentioned, for example.
  • the surface roughness, for example Ra of a glass base plate or a glass substrate can be measured using a general surface roughness measuring machine.
  • the glass material has a surface in contact with the molten metal and the other surface.
  • the upper surface is the contact surface 1A
  • the lower surface is the free surface 1B.
  • a cut line is formed on the contact surface 1A of the glass material 1 to draw a curve that forms a substantially peripheral edge of a region to be a magnetic disk glass substrate.
  • circular cut lines 2 and 3 are formed on the contact surface 1A of the glass material 1 with the glass cutter 4 to draw the disc-shaped outer peripheral side and inner peripheral side, respectively. To do.
  • the cut lines 2 and 3 on the outer peripheral side and the inner peripheral side are formed obliquely with respect to the thickness direction of the glass plate. Further, in the present embodiment, the cut lines 2 and 3 are formed obliquely outward from the contact surface 1A of the glass material 1 toward the free surface 1B side, and when viewed in the cross-sectional view of FIG.
  • the incisors 2 and 2 and the incisors 3 and 3 are formed in a C-shape.
  • the cut lines 2 and 3 are formed obliquely outward from the contact surface 1A of the glass material 1 toward the free surface 1B, but the present invention is not limited thereto, and for example, the contact surface 1A of the glass material 1 Incisions 2 and 3 are formed obliquely inward from the free surface 1B side, and when viewed in FIG. 2 (b), the left and right incisions 2 and 2 and the incisions 3 and 3 are respectively in a reverse C shape. It is also possible to advance the cutting line so that the inner part surrounded by the cutting line is extracted upward.
  • the cut lines 2 and 3 formed on the contact surface 1A of the glass material 1 are advanced toward the free surface 1B side. Thereby, the inner region 10 a surrounded by the cut line 2 is separated from the glass material 1. Further, the inner portion 10 b surrounded by the cut line 3 is separated from the region 10 a surrounded by the cut line 2.
  • means for advancing the incisions 2 and 3 formed on the contact surface 1A of the glass material 1 in this way toward the free surface 1B side means for causing a difference in thermal expansion in the glass material 1, for example, the glass material 1
  • a method of heating one side is preferred. By heating the glass material 1, a difference in thermal expansion occurs in the thickness direction of the glass material 1, and the glass material can be easily cut into a target disk shape.
  • the glass substrate after the cutting step has a surface roughness Ra of 5 nm to 50 nm and a maximum height roughness Rz of 20 nm to 100 nm. If the surface roughness Ra or the maximum height roughness Rz of the glass base plate after the cutting process is too high, grinding damage is large, and if it is too low, the grinding process cannot be performed.
  • the chemical treatment step may be performed so that the surface roughness Ra becomes the above value after the cutting step.
  • This chemical treatment step is a step for facilitating processing by etching the glass surface using a solution capable of dissolving glass, such as hydrofluoric acid, and roughening the surface.
  • the disk processing step of the present invention may include a step of polishing a corner (end face) of each cut line after the cutting step. By this end surface polishing step, cracks on the glass substrate caused by the cut lines can be reduced.
  • the outer diameter r1 is 2.5 inches (about 64 mm), 1.8 inches (about 46 mm), 1 inch (about 25 mm), 0.8 inches (about 20 mm), etc., and the thickness is It is processed into a disk-shaped glass base plate of 2 mm, 1 mm, 0.63 mm or the like. Further, when the outer diameter r1 is 2.5 inches (about 64 mm), the inner diameter r2 is processed to 0.8 inches (about 20 mm) or the like.
  • Surface waviness is a three-dimensional surface shape formed on the surface of a glass material, and can be a surface shape configured by selecting a wavelength band shape having a shape wavelength of 0.1 mm to 5 mm. .
  • the surface waviness can be grasped by observing a predetermined region of the glass material with a microscope or the like.
  • Optiflat manufactured by Phase Shift Technology can be preferably used.
  • the grinding apparatus used in the lapping process is not particularly limited as long as it is a grinding apparatus used for manufacturing a glass substrate. Specifically, there is a grinding apparatus 1 as shown in FIG. FIG. 3 is a schematic cross-sectional view showing an example of a grinding apparatus used in the lapping step in the method for manufacturing a glass substrate for magnetic information recording media according to the embodiment of the present invention.
  • the grinding apparatus 5 includes an apparatus main body 5a and a coolant supply section 5b that supplies coolant, which is a coolant, to the apparatus main body 5a.
  • the apparatus main body 5a is provided with a disk-shaped upper surface plate 6 and a disk-shaped lower surface plate 7, and they are arranged at intervals in the vertical direction so that they are parallel to each other. Then, the disk-shaped upper surface plate 6 and the disk-shaped lower surface plate 7 rotate in directions opposite to each other.
  • fixed abrasive grains 8 containing diamond particles are provided.
  • the fixed abrasive grains 8 containing diamond particles used in the lapping step may be in the form of pellets obtained by bonding a plurality of diamond particles with a resin, or by upper or lower platen 6 and lower surface by adhesion or electrodeposition using a resin. You may use the sheet-like thing which adhered the diamond particle to the board
  • a carrier may be sandwiched between the fixed abrasive 8 and the surface plates 2 and 3.
  • the carrier revolves in the same direction as the lower surface plate 7 with respect to the center of rotation of the surface plates 6 and 7 while rotating while holding the plurality of glass base plates 10.
  • the disk-shaped upper surface plate 6 and the disk-shaped lower surface plate 7 can be operated by separate driving.
  • the coolant 11 is supplied between the fixed abrasive grains 8 and the glass base plate 10 and between the fixed abrasive grains 8 and the glass base plate 10, whereby the glass base material is supplied.
  • the plate 10 can be ground.
  • the coolant supply unit 5 b includes a container in which the coolant 11 is put and a pump 9. That is, the coolant 11 in the container is supplied into the surface plates 2 and 3 by the pump 9 and circulated.
  • the facets from which the grinding surfaces of the upper and lower surface plates 6 and 7 are cut off which are generated during the circulation are removed from the respective grinding surfaces. Specifically, when the coolant 11 is circulated, the coolant is filtered with a filter provided in the lower surface plate 7, and the facet is retained in the filter.
  • the lapping step should be a step in which the entire surface of the glass base plate has a substantially uniform surface roughness.
  • a general glass base plate grinding machine having upper and lower surface plates differs in grinding ability between the upper and lower surface plates. That is, since the execution pressure varies depending on factors due to gravity, the grinding performance of the upper surface plate is slightly superior to that of the lower surface plate.
  • the machining rate is a value obtained by dividing the machining allowance by the machining time. Deviating from the processing rate ratio may result in a glass substrate having a poor processing balance.
  • the present inventors have paid attention to the fact that the number of cracks in the surface on which the cut lines are formed in the above-described disk machining process is larger than the number of the surfaces in which the cut lines are not formed. This is because the cut line is used as a starting point during the cutting process of the glass material, and cracks frequently occur from the starting point to the periphery.
  • this crack in the polishing process since it is processed along the crack part, it may remain as a pit or swell, so it needs to be removed in the grinding process.
  • these cracks are generated in the vicinity of the end face (the part where the cut line has entered), and since it is difficult to apply a processing pressure in the polishing process, it is difficult to remove by the polishing process.
  • the effective pressure applied to the substrate is constant compared to the lower platen (therefore, the effective pressure is large), so cracks can be removed efficiently.
  • the grinding process is performed together with the grinding liquid, but the grinding liquid is concentrated on the lower surface plate side by gravity. Since the grinding fluid is constantly circulated and processing is performed while removing glass sludge (glass waste) with a filter, the sludge-removed grinding fluid always flows on the upper platen side, while sludge is on the lower platen side. It becomes easy to accumulate. This sludge makes it difficult to remove cracks (sludge may grow cracks), and as a result, cracks remain until the final substrate.
  • the surface roughness Ra of the glass base plate used in the polishing process performed by the lapping process is preferably 0.5 ⁇ m or less, and more preferably 0.3 ⁇ m or less.
  • the maximum height roughness Rz is preferably 3 ⁇ m or less. This is to facilitate the polishing process.
  • the removal allowance of the glass base plate in the lapping step is preferably 50 ⁇ m or more and 300 ⁇ m or less, and more preferably 100 ⁇ m or more and 200 ⁇ m or less. If the advance allowance is less than 50 ⁇ m, cracks generated on the surface with the cut line may remain, and if it is greater than 300 ⁇ m, the processing time becomes long, resulting in poor efficiency of the manufacturing method.
  • the machining allowance for grinding both surfaces of the glass base plate is 50 ⁇ m or more, and more preferably 100 ⁇ m or more. If the machining allowance is smaller than 50 ⁇ m, there is a possibility that a crack generated on the surface with the cut line remains.
  • this wrapping process may be performed once or twice or more.
  • first lapping process the parallelism, flatness and thickness of the glass base plate are preliminarily adjusted in the first lapping process (first lapping process), and glass is used in the second lapping process (second lapping process). It becomes possible to finely adjust the parallelism, flatness and thickness of the base plate.
  • the rough polishing step (primary polishing step) is intended to remove the scratches and distortions remaining in the lapping step described above by polishing the main surface of the glass base plate with a polishing slurry containing cerium oxide.
  • the following polishing method is used.
  • the polishing apparatus used in the rough polishing step is not particularly limited as long as it is a polishing apparatus used for manufacturing a glass substrate.
  • the surface to be polished in the rough polishing step is a main surface and / or an end surface.
  • the main end surface is a surface parallel to the surface direction of the glass base plate.
  • the end surface is a surface composed of an inner peripheral end surface and an outer peripheral end surface.
  • an inner peripheral end surface is a surface which has an inclination with respect to the surface of an inner peripheral side perpendicular
  • an outer peripheral end surface is a surface which has an inclination with respect to the surface direction of the outer peripheral side perpendicular
  • the abrasive used in the polishing step of the present invention contains cerium oxide as a main component.
  • the content of cerium oxide is preferably 3 to 15% by mass with respect to the total amount of the polishing slurry. By setting it as such a range, the glass substrate for magnetic information recording media with higher smoothness can be manufactured.
  • the polishing slurry is a liquid in which the abrasive, dispersant, etc. are dispersed in water, that is, a slurry liquid.
  • a slurry liquid In the state where the abrasive is dispersed in water, even if the alkaline earth metal is contained in the water, the alkaline earth metal is dissolved, so that it hardly adheres to the surface of the glass base plate and is included in the abrasive. Alkaline earth metal tends to adhere to the surface of the glass base plate. For this reason, the use of an abrasive containing a small amount of alkaline earth metal can sufficiently suppress the adhesion of alkaline earth metal to the polished glass base plate.
  • alkali metal ions such as lithium ions and sodium ions contained in the glass base plate are potassium having a larger ion radius. This is performed by an ion exchange method in which the alkali metal ions such as ions are substituted. Due to the strain caused by the difference in ion radius, compressive stress is generated in the ion-exchanged region, and the surface of the glass base plate is strengthened.
  • a strengthening layer is suitably formed by this chemical strengthening process by using the glass composition as described above as a glass base plate that is a raw material of the glass substrate.
  • the glass composition as described above as a glass base plate that is a raw material of the glass substrate.
  • the content of Na 2 O is large, and the sodium ions of Na 2 O are chemically strengthened. This is thought to be because it is easily exchanged for potassium ions contained in.
  • the polishing agent used in the polishing step before the chemical strengthening step here the rough polishing step, is an abrasive having the above composition, the alkaline earth metal adhering to the surface of the glass base plate is used. The amount is small and the chemical strengthening is considered to be uniform. Therefore, a glass substrate excellent in impact resistance can be produced by performing a precision polishing step on a glass base plate that has been subjected to suitable chemical strengthening as in this embodiment.
  • the chemical strengthening treatment solution is not particularly limited as long as it is a chemical strengthening treatment solution used in the chemical strengthening step in the method for producing a glass substrate for a magnetic information recording medium.
  • a melt containing potassium ions a melt containing potassium ions and sodium ions, and the like can be given.
  • melts obtained by melting potassium nitrate, sodium nitrate, potassium carbonate, sodium carbonate, and the like examples include melts obtained by melting potassium nitrate, sodium nitrate, potassium carbonate, sodium carbonate, and the like.
  • a melt obtained by melting potassium nitrate and a melt obtained by melting sodium nitrate are preferably mixed in approximately the same amount.
  • the precision polishing step maintains a flat and smooth main surface obtained in the rough polishing step, and for example, a mirror surface polishing process for finishing the surface to a smooth mirror surface with a maximum height roughness (Rz) of about 6 nm or less.
  • This precision polishing step is performed, for example, by using a polishing apparatus similar to that used in the rough polishing step and replacing the polishing pad from a hard polishing pad to a soft polishing pad.
  • the surface to be polished in the precision polishing step is the main surface, similar to the surface to be polished in the rough polishing step.
  • abrasive used in the precision polishing process an abrasive that causes less scratching even if the polishing performance is lower than that used in the rough polishing process is used.
  • a polishing agent containing silica-based abrasive grains having a particle diameter lower than that of the polishing agent used in the rough polishing step.
  • the average particle diameter of the silica-based abrasive is preferably about 20 nm.
  • polishing agent is supplied to a glass base plate, a polishing pad and a glass base plate are slid relatively, and the surface of a glass base plate is mirror-polished.
  • SiO 2, Al 2 O 3 , and B 2 O 3 is a framework component of the glass workpiece.
  • Li 2 O, Na 2 O, and K 2 O are alkali components of the glass base plate.
  • MgO, CaO, BaO, SrO, and ZnO are alkaline earth components of the glass base plate.
  • the skeletal component of the glass base plate used in the present embodiment is 58 to 70% by mass of SiO 2 , 12 to 18% by mass of Al 2 O 3 , and 0 to 3% by mass of B 2 O 3. (Including 0), and the total thereof, that is, the total of SiO 2 , Al 2 O 3 and B 2 O 3 is 72 to 85 mass%.
  • SiO 2 is a component that forms a glass skeleton (matrix). If the content of SiO 2 is too small, the glass structure becomes unstable and the chemical durability is deteriorated, and the viscosity characteristics at the time of melting are deteriorated, which may impair the moldability. If the content of SiO 2 is too large, with the productivity becomes poor meltability decreases, sufficient rigidity may become impossible to obtain. Therefore, the content of SiO 2 is preferably 58 to 70% by mass.
  • Al 2 O 3 is also a component that forms a skeleton of glass, and contributes to improvement of durability and strength and surface hardness of glass. If the content of Al 2 O 3 is too small, the durability and strength may not be sufficient as a glass substrate for a magnetic information recording medium. Further, when the content of Al 2 O 3 is too large, intensified devitrification tendency of the glass, it may stable glass formation is difficult. Therefore, the content of Al 2 O 3 is preferably 12 to 18% by mass.
  • B 2 O 3 has the effect of improving the chemical durability by improving the meltability and improving the productivity and stabilizing the glass structure by entering the glass skeleton.
  • B 2 O 3 tends to volatilize when melted, and the glass component ratio tends to become unstable.
  • the strength is lowered, the hardness is lowered, the glass substrate is easily damaged, the fracture toughness value is reduced, and the substrate tends to be damaged.
  • the content of B 2 O 3 is preferably 3% by mass or less.
  • 0 mass% in the content of B 2 O 3 of 0 to 3 mass% means that an embodiment not containing B 2 O 3 can be included.
  • the notation of “0 mass%” in the glass composition of the present application document is in agreement with this, and means that it may include an embodiment not containing the component (hereinafter, the same notation is agreed).
  • the total amount w (FMO) of SiO 2 , Al 2 O 3 and B 2 O 3 is preferably 70 to 85% by mass. This is to stabilize the glass structure. If the total amount is too small, the glass structure tends to become unstable. Moreover, when there is too much this total amount, the viscosity characteristic at the time of a fusion
  • the alkali component of the glass base plate used in the present embodiment is 1 to 8% by mass of Li 2 O, 2 to 13% by mass of Na 2 O, and 0.2 to 2% by mass of K 2 O.
  • the total of these, that is, the total of Li 2 O, Na 2 O and K 2 O is 3.2 to 23% by mass.
  • Li 2 O has a unique property among alkali metal elements, and has a function of improving the solubility of the glass, while greatly improving the Young's modulus by improving the ion filling rate in the glass structure. Has an effect. Li 2 O content is too small, there is a tendency that it is impossible to exhibit sufficient effect on improvement of the improvement and the Young's modulus of solubility. Further, the content of Li 2 O, is too large, as described above, there are cases where the surface of the recording layer of the information recording medium serving as a trigger of a very small and thin reaction precipitates. Therefore, the content of Li 2 O is preferably 1 to 8% by mass.
  • Na 2 O has an effect of lowering the melting temperature of the glass, the effect of increasing the coefficient of linear expansion. Further, it is considered to be a component that greatly affects the chemical strengthening effect in the chemical strengthening process. That is, when the content of Na 2 O is too small, not only does the melting temperature tend not to be sufficiently lowered, but the strength cannot be sufficiently increased by the chemical strengthening step. On the other hand, if the content of Na 2 O is too large, the amount of elution increases and the recording layer may be adversely affected. Therefore, the content of Na 2 O is preferably 2 to 13% by mass. In addition, this content is more than the content in a general glass substrate.
  • K 2 O is, have the effect of lowering the melting temperature of the glass, the effect of increasing the coefficient of linear expansion.
  • the content of K 2 O is too small, there is a tendency that the melting temperature cannot be lowered sufficiently.
  • the content of K 2 O is too large, not only does the amount of elution increase and the recording layer may be adversely affected, but there is a tendency that the strength cannot be sufficiently increased by the chemical strengthening step. This is thought to be due to the fact that the chemical strengthening process replaces potassium ions instead of sodium ions of Na 2 O to form a strengthened layer and inhibits this exchange. Therefore, the content of K 2 O is preferably 0.2 to 2% by mass.
  • MgO, CaO, BaO, SrO, and ZnO which are alkaline earth components of the glass base plate, have the effect of increasing the thermal expansion coefficient, rigidity, etc. and improving the meltability.
  • the total amount w (MgO + CaO + BaO + SrO + ZnO) of MgO, CaO, BaO, SrO and ZnO is preferably 1 to 10% by mass. If the total amount is too small, the effect of improving rigidity and improving meltability tends to be insufficient. Moreover, when there is too much this total amount, there exists a tendency for a chemical structure to fall while glass structure becomes unstable and melt productivity falls.
  • a glass base plate you may contain components other than the above. Specifically, for example, ZrO 2 or cerium oxide may be contained.
  • the ZrO 2 content is preferably 0 to 5% by mass.
  • the content of cerium oxide is preferably 0 to 2% by mass.
  • cerium oxide has an effect which suppresses generation
  • FIG. 4 is a partial cross-sectional perspective view showing a magnetic disk which is an example of a magnetic recording medium using the glass substrate for magnetic information recording medium manufactured by the method for manufacturing a glass substrate for magnetic information recording medium according to the present embodiment. is there.
  • the magnetic disk D includes a magnetic film 102 formed on the main surface of a circular glass substrate 101 for a magnetic information recording medium. For the formation of the magnetic film 102, a known method is used.
  • a formation method for forming a magnetic film 102 by spin-coating a thermosetting resin in which magnetic particles are dispersed on a glass substrate 101 for a magnetic information recording medium, or a glass substrate for a magnetic information recording medium
  • a formation method for forming the magnetic film 102 on the substrate 101 by sputtering
  • a formation method electroless plating method
  • electroless plating method for forming the magnetic film 102 on the glass substrate 101 for magnetic information recording medium by electroless plating
  • the thickness of the magnetic film 102 is about 0.3 to 1.2 ⁇ m in the case of the spin coating method, and about 0.04 to 0.08 ⁇ m in the case of the sputtering method, and is based on the electroless plating method. In some cases, the thickness is about 0.05 to 0.1 ⁇ m. From the viewpoint of thinning and densification, film formation by sputtering is preferable, and film formation by electroless plating is preferable.
  • the magnetic material used for the magnetic film 102 can be any known material and is not particularly limited.
  • the magnetic material is preferably, for example, a Co-based alloy based on Co having high crystal anisotropy in order to obtain a high coercive force, and Ni or Cr added for the purpose of adjusting the residual magnetic flux density. More specifically, CoPt, CoCr, CoNi, CoNiCr, CoCrTa, CoPtCr, CoNiPt, CoNiCrPt, CoNiCrTa, CoCrPtB, CoCrPtSiO, and the like whose main component is Co can be given.
  • the magnetic film 102 has a multilayer structure (for example, CoPtCr / CrMo / CoPtCr, CoCrPtTa / CrMo / CoCrPtTa, etc.) divided by a nonmagnetic film (for example, Cr, CrMo, CrV, etc.) in order to reduce noise.
  • a multilayer structure for example, CoPtCr / CrMo / CoPtCr, CoCrPtTa / CrMo / CoCrPtTa, etc.
  • ferrite or iron - may be a rare earth, also, Fe in a non-magnetic film made of SiO 2, BN, etc., Co, FeCo, CoNiPt and the like
  • a granular material having a structure in which the magnetic particles are dispersed may be used.
  • either an inner surface type or a vertical type recording format may be used for recording on the magnetic film 102.
  • the surface of the magnetic film 102 may be thinly coated with a lubricant.
  • a lubricant include those obtained by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a freon-based solvent.
  • an underlayer or a protective layer may be provided for the magnetic film 102.
  • the underlayer in the magnetic disk D is appropriately selected according to the magnetic film 102.
  • the material for the underlayer include at least one material selected from nonmagnetic metals such as Cr, Mo, Ta, Ti, W, V, B, Al, and Ni.
  • the material of the underlayer is preferably Cr alone or a Cr alloy from the viewpoint of improving magnetic characteristics.
  • the underlayer is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are stacked.
  • Examples of such an underlayer having a multilayer structure include multilayer underlayers such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, and NiAl / CrV.
  • Examples of the protective layer that prevents wear and corrosion of the magnetic film 102 include a Cr layer, a Cr alloy layer, a carbon layer, a hydrogenated carbon layer, a zirconia layer, and a silica layer. These protective layers can be continuously formed with the underlayer and the magnetic film 102 by an in-line sputtering apparatus. These protective layers may be a single layer, or may be a multi-layer structure composed of the same or different layers.
  • a SiO 2 layer may be formed on the Cr layer.
  • Such a SiO 2 layer is formed by dispersing and applying colloidal silica fine particles in a tetraalkoxysilane diluted with an alcohol-based solvent on the Cr layer and further baking.
  • the glass substrate 101 for magnetic information recording medium is formed with the above-described composition. It can be done with high reliability.
  • the glass substrate 101 for magnetic information recording media in this embodiment was used for a magnetic recording medium
  • the glass substrate for magnetic information recording media in this embodiment 101 can also be used for magneto-optical disks, optical disks, and the like.
  • a general glass substrate, an abrasive and a polishing pad used for manufacturing a glass substrate for an information recording medium were prepared.
  • the composition of the polishing agent and the polishing pad includes those contained in general polishing agents and polishing pads used in the production of a glass substrate for information recording media.
  • Example 1 Using a glass substrate, a glass substrate is prepared using a float method, and by a known method, a disk processing step, a lapping step, a rough polishing step (primary polishing step), a chemical strengthening step, a precision polishing step (secondary polishing step) ) And a final washing step.
  • the lapping process was ground so that the machining allowance was 150 ⁇ m.
  • processing was performed using a sheet-like diamond tile (concentration: 200, particle size: 2 ⁇ m) in which diamond particles were planarly bonded to the upper surface plate 6 and the lower surface plate 7.
  • the surface roughness of the substrate after the lapping process was 0.21 ⁇ m.
  • the surface roughness measuring machine was measured with a contact-type roughness measuring machine (manufactured by KLA tencol).
  • the main surface roughness of the glass substrate after the rough polishing step, the precision polishing step, and the cleaning / drying step was 0.9 mm.
  • the surface roughness Ra was measured with an atomic force microscope (AFM).
  • the measurement used AFM DimensionV of Veeco. A 10 ⁇ m ⁇ 10 ⁇ m scan line was performed at 256.
  • Example 2 In the lapping step, the same procedure as in Example 1 was performed except that the grinding allowance was 50 ⁇ m. The surface roughness Ra after the lapping process was 0.53 ⁇ m. The surface roughness of the final substrate was 1.0 mm.
  • ⁇ ... Defect rate is less than 5% ⁇ ... 5% or more and less than 10% ⁇ ... 10% or more
  • the method for manufacturing a glass substrate for a magnetic information recording medium includes a cutting step of cutting a glass material along one surface of a glass material, and cutting the glass material along the cutting material, and a fixed abrasive containing diamond particles.
  • the ratio between the processing rate of the upper surface plate and the processing rate of the lower surface plate is 1: 0.8 to 1: 0.98 in the lapping step. Preferably it is.
  • the glass substrate after the lapping step has a surface roughness Ra of 0.5 ⁇ m or less and a maximum height roughness Rz of 3 ⁇ m or less.
  • the manufacturing method of the glass substrate for magnetic information recording media which is excellent in a glide characteristic when mounted in a hard disk can be provided.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Surface Treatment Of Glass (AREA)
  • Magnetic Record Carriers (AREA)

Abstract

L'objet de la présente invention est proposer un procédé de fabrication d'un substrat en verre pour un support d'enregistrement magnétique d'informations. Ledit procédé est capable de réduire le nombre de fissures dans les surfaces d'une plaque de verre brut, et le substrat en verre résultant possède d'excellentes caractéristiques de glissement lorsqu'il est monté dans un disque dur. Ledit procédé comprend une étape de coupe, à laquelle une surface de verre est entaillée et le verre est coupé le long desdites entailles, et une étape de rodage à laquelle les surfaces de la plaque de verre brut sont meulées à l'aide de plateaux de rodage supérieur et inférieur portant un abrasif fixe contenant des particules de diamant placé sur leurs surfaces de meulage. Ce procédé de fabrication est caractérisé en ce qu'à ladite étape de rodage, la surface entaillée est placée côté plateau de rodage supérieur et la surface non entaillée est placée côté plateau de rodage inférieur. Le rapport entre la vitesse de traitement du plateau de rodage supérieur et la vitesse de traitement du plateau de rodage inférieur à l'étape de rodage est de préférence compris entre 1 :0,8 et 1 :0,98 inclus.
PCT/JP2011/006481 2010-12-27 2011-11-22 Procédé de fabrication de substrat en verre pour support d'enregistrement magnétique d'informations WO2012090377A1 (fr)

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WO2014156795A1 (fr) * 2013-03-28 2014-10-02 Hoya株式会社 Substrat en verre pour supports d'enregistrement d'informations et procédé pour leur production

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007122849A (ja) * 2005-09-28 2007-05-17 Hoya Corp 磁気ディスク用ガラス基板の製造方法及び磁気ディスクの製造方法
JP2010080016A (ja) * 2008-09-27 2010-04-08 Hoya Corp 磁気ディスク用ガラス基板の製造方法及び磁気ディスクの製造方法
WO2010041537A1 (fr) * 2008-10-08 2010-04-15 コニカミノルタオプト株式会社 Procédé pour produire un substrat de verre, et procédé pour produire un support d'enregistrement magnétique
JP2010238272A (ja) * 2009-03-30 2010-10-21 Hoya Corp 磁気ディスク用ガラス基板の製造方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007122849A (ja) * 2005-09-28 2007-05-17 Hoya Corp 磁気ディスク用ガラス基板の製造方法及び磁気ディスクの製造方法
JP2010080016A (ja) * 2008-09-27 2010-04-08 Hoya Corp 磁気ディスク用ガラス基板の製造方法及び磁気ディスクの製造方法
WO2010041537A1 (fr) * 2008-10-08 2010-04-15 コニカミノルタオプト株式会社 Procédé pour produire un substrat de verre, et procédé pour produire un support d'enregistrement magnétique
JP2010238272A (ja) * 2009-03-30 2010-10-21 Hoya Corp 磁気ディスク用ガラス基板の製造方法

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