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WO2013145503A1 - Procédé de production de substrat en verre pour disques durs - Google Patents

Procédé de production de substrat en verre pour disques durs Download PDF

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Publication number
WO2013145503A1
WO2013145503A1 PCT/JP2013/000125 JP2013000125W WO2013145503A1 WO 2013145503 A1 WO2013145503 A1 WO 2013145503A1 JP 2013000125 W JP2013000125 W JP 2013000125W WO 2013145503 A1 WO2013145503 A1 WO 2013145503A1
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WO
WIPO (PCT)
Prior art keywords
glass
glass substrate
blanks
heat treatment
polishing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2013/000125
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English (en)
Japanese (ja)
Inventor
大士 梶田
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Konica Minolta Inc
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Konica Minolta Inc
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Filing date
Publication date
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Publication of WO2013145503A1 publication Critical patent/WO2013145503A1/fr
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B25/00—Annealing glass products
    • C03B25/02—Annealing glass products in a discontinuous way
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B32/00—Thermal after-treatment of glass products not provided for in groups C03B19/00, C03B25/00 - C03B31/00 or C03B37/00, e.g. crystallisation, eliminating gas inclusions or other impurities; Hot-pressing vitrified, non-porous, shaped glass products
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B32/00—Thermal after-treatment of glass products not provided for in groups C03B19/00, C03B25/00 - C03B31/00 or C03B37/00, e.g. crystallisation, eliminating gas inclusions or other impurities; Hot-pressing vitrified, non-porous, shaped glass products
    • C03B32/005—Hot-pressing vitrified, non-porous, shaped glass products
    • 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
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2215/00—Press-moulding glass
    • C03B2215/40—Product characteristics
    • C03B2215/44—Flat, parallel-faced disc or plate products

Definitions

  • the present invention relates to a method for manufacturing a glass substrate for HDD.
  • the methods for improving the shape quality of the glass substrate there is a method of correcting warpage in the heat treatment process of glass blanks. Specifically, in order to correct the warp generated in the glass blanks when the molten glass is press-molded, the glass blanks after press molding are softened by applying heat, and in that state the flatness is better than the glass blanks There is a method of correcting the warp by sandwiching both main surfaces of the glass blanks with a setter (flatness of about several ⁇ m) and applying pressure.
  • thermal assist heat resistance is required for the glass substrate. Therefore, it is necessary to use a glass material having a high glass transition temperature (Tg) as a raw material, and in order to correct the flatness of glass blanks made of such a glass material, it is necessary to perform heat treatment at a higher temperature than before. .
  • Tg glass transition temperature
  • Patent Document 1 discloses a method of correcting warpage of a glass blank by applying pressure to the main surface of the glass blank at a temperature below the yield point of the glass material and exceeding the strain point in the heat treatment step.
  • the manufacturing method described in Patent Document 1 does not take into account the surface shape of the setter that contacts the glass blanks. Therefore, the glass blanks that have been heat-treated by the manufacturing method described in Patent Document 1 are partly fused with the setter and peeled off, and the surface properties deteriorate. Since the glass blanks with deteriorated surface properties cause undulation in a grinding process or the like, there is a problem that the obtained glass substrate easily causes a subsequent error and cannot be used as a recent large-capacity medium.
  • the present invention has been made in view of such conventional problems, and can prevent fusion between glass blanks and setters in a heat treatment step, and the glass substrate for HDD having high shape quality of the obtained glass substrate.
  • An object is to provide a manufacturing method.
  • a method for producing a glass substrate according to one aspect of the present invention is a method for producing a glass substrate having a recording density of 500 GB / sheet or more, and a glass melting step for melting a glass material, and forming glass blanks by forming molten glass And a heat treatment step of heat-treating the glass blanks, wherein the heat treatment is performed by sandwiching both main surfaces of the glass blanks with a setter having a surface roughness of 0.1 to 10 ⁇ m. To do.
  • FIG. 1 is an explanatory diagram for explaining a glass melting step, a press forming step, and a heat treatment step in the method for manufacturing a glass substrate according to an embodiment of the present invention.
  • the glass substrate is, for example, a glass melting step, a molding step, a heat treatment step, a coring step, a grinding step (lapping step), a first polishing step (rough polishing step), or a second polishing. It is manufactured through a process (precision polishing process) and a final cleaning process.
  • This embodiment is characterized by a heat treatment process. In the heat treatment step, glass blanks produced through the glass melting step and the forming step are heat treated.
  • each process is demonstrated in order.
  • the glass melting step is a step of melting a glass material.
  • the glass material include aluminosilicate glass, soda lime glass, borosilicate glass, Li 2 O—SiO 2 glass, Li 2 O—Al 2 O 3 —SiO 2 glass, R′O—Al 2 O 3.
  • R ′ Mg, Ca, Sr, Ba
  • this embodiment since the surface roughness of the setter used in the heat treatment step described later is adjusted to 0.1 to 10 ⁇ m, even when glass blanks made of such a high Tg glass material are heat treated. The fusion of the glass blanks and the setter can be prevented. Therefore, this embodiment can produce glass blanks with high shape quality, and can employ a heat assist method in which heat treatment is performed at a high temperature in the magnetic film forming step described later. Moreover, since the glass substrate produced by this embodiment has high shape quality, it can be used as a medium with a large capacity such as 500 GB / sheet or more with a small flying height.
  • FIG. 1 is an explanatory diagram for explaining a glass melting step, a forming step, and a heat treatment step in the glass substrate manufacturing method of the present embodiment.
  • a glass melting step a method of suspending a glass material (molten glass 2) melted in a melting furnace 1 onto a lower mold 3 of a press used in a molding step described later is illustrated.
  • Reference numeral 4 indicates a suspended molten glass (glass gob).
  • the glass gob refers to a molten glass lump obtained by cutting molten glass with a blade.
  • the obtained molten glass (glass gob 4) is molded by a molding process.
  • the forming step is a step of obtaining glass blanks from molten glass.
  • the method of forming the glass gob in the forming step is not particularly limited.
  • a method (press forming) in which a molten glass material is poured into a lower mold and press-formed with an upper mold to obtain a disk-shaped glass blank can be adopted. it can.
  • the glass gob 4 is pressurized from the upper and lower sides with the press machine 5, and the method of producing the intermediate molded object (glass blanks 6) is illustrated.
  • the obtained glass blanks 6 are subjected to heat treatment by a heat treatment step.
  • the glass blanks are not limited to press molding, and may be produced by cutting out sheet glass formed by, for example, a downdraw method or a float method with a grinding wheel. In this molding process, foreign matter and bubbles are mixed in or near the surface of the glass blanks, and defects are generated.
  • the size of the glass blank is not particularly limited, and glass blanks having various sizes such as an outer diameter of 2.5 inches, 1.8 inches, 1 inch, and 0.8 inches can be manufactured. In particular, when 2.5-inch glass blanks are produced, they can be used in portable devices such as notebook computers that have excellent impact resistance and are less likely to cause subsequent errors.
  • the thickness of the glass blanks is not particularly limited, and for example, glass blanks having various thicknesses such as 2 mm, 1 mm, 0.8 mm, and 0.63 mm can be produced.
  • the heat treatment process (hereinafter sometimes referred to as the annealing process) is performed in a high-temperature heating furnace while pressing both main surfaces of the glass blanks produced through the glass melting process and the molding process with a setter made of a heat-resistant member. It is the process of reducing the curvature of glass blanks and improving shape quality by heating by.
  • the glass blanks 6 are heated in a heating furnace 8 with both main surfaces sandwiched between setters 7 in a heat treatment step.
  • the number of glass blanks 6 alternately sandwiched between setters 7 is not particularly limited, and may be one or more. For example, 30 glass blanks 6 can be alternately sandwiched between setters 7 to produce a bundle of laminated glass blanks 6. The bundle of produced glass blanks 6 can be carried into the heating furnace 8 and subjected to heat treatment.
  • the setter 7 is not particularly limited as long as the setter 7 has better flatness than the glass blank 6 and has heat resistance.
  • raw materials constituting the setter 7 include stainless steel (austenitic and martensitic), castings (FC (Ferrum Casting), FCD (Ferrum Casting Ductile)), heat resistant alloys (Co and Ni), ceramics, and the like. (Al 2 O 3 , ZrO 2 , SiC, SiN 3 ) or the like can be used. Further, the surface of the setter 7 can be subjected to treatment such as Cr plating and Ni—P electroless plating which are hard and difficult to oxidize.
  • the surface roughness of the main surface of the setter 7 that comes into contact with the glass blanks 6 is preferably 0.1 to 10 ⁇ m, and more preferably 0.5 to 5 ⁇ m.
  • the surface roughness of the setter 7 is less than 0.1 ⁇ m, the contact area between the glass blanks 6 and the setter 7 becomes large, and therefore the glass blanks 6 and the setter 7 may be fused.
  • the surface roughness of the setter 7 exceeds 10 ⁇ m, the surface properties of the glass blanks 6 may deteriorate, and the surface roughness of the resulting glass substrate may deteriorate.
  • the surface roughness of the setter in this embodiment means arithmetic mean roughness Ra defined in JIS B0601.
  • the method of pressurizing the glass blanks 6 sandwiched between the setters 7 is not particularly limited, and for example, a method using a weight load, a spring, an air cylinder, or the like can be employed.
  • the pressure at the time of pressurization is not particularly limited, and can be, for example, 0.01 to 10 kg / cm 2 .
  • the size of the main surface of the setter 7 is not particularly limited as long as it is larger than the area of the main surface of the glass blanks 6 after the heat treatment.
  • the heat treatment step can be roughly divided into a heat retention step for maintaining the glass blanks 6 at a predetermined heat treatment temperature and a temperature lowering step for cooling from the heat treatment temperature.
  • the time required for the heat insulation process can be, for example, 3 minutes to 10 hours. By setting the heat retention time within this range, warpage of the glass blanks 6 can be reduced.
  • the temperature (heat treatment temperature) of the glass blanks 6 during the heat retention is not particularly limited as long as it is equal to or higher than Tg of the glass material constituting the glass blanks 6 and lower than the softening point.
  • the heat treatment temperature can be, for example, Tg to Tg + 70 ° C. of the glass material.
  • the heat treatment temperature can be set to 530 ° C. or 560 ° C.
  • heat processing temperature can be set to 620 degreeC.
  • the surface roughness of the main surface of the setter 7 is adjusted to be 0.1 to 10 ⁇ m. Therefore, even when the heat treatment temperature is set to a high temperature such as Tg + 70 ° C., the glass blanks 6 and the setter 7 are hardly fused. As a result, a glass material having a high Tg can be used as a raw material, and a glass substrate having a high shape quality can be obtained even if such a glass material having a high Tg is used.
  • the time required for the temperature lowering step is preferably 5 to 30 hours, more preferably 10 to 20 hours, from the viewpoint of suppressing internal strain.
  • the temperature is lowered until the temperature of the glass blanks 6 reaches the temperature of the strain point of the glass.
  • the cooling rate can be, for example, 2 to 12 ° C./hour.
  • the internal strain can be sufficiently suppressed by cooling to the strain point of the glass material by setting the temperature drop time to 10 hours or more.
  • the glass blanks 6 that have undergone the above heat treatment process are adjusted to have a thickness of, for example, 0.5 to 2 mm.
  • the glass substrate obtained according to the present embodiment can be used as a large-capacity medium having a recording density of 500 GB / sheet or more by forming a magnetic film by a magnetic film forming process described later.
  • the manufacturing method of the glass substrate of this embodiment is not specifically limited about the process after a heat treatment process. Therefore, the process described below is an example, and the design can be changed as appropriate.
  • the coring step is a step of making a circular hole (center hole) in the center of the glass blank.
  • the coring step is a step of forming an annular glass blank by forming an inner hole in the center of the glass blank using, for example, a cylindrical diamond drill.
  • the grinding process is a process of preliminarily adjusting the parallelism, flatness, and thickness by grinding (lapping) both main surfaces of the glass blanks.
  • Grinding can be performed using alumina free abrasive grains by a double-sided lapping device using a planetary gear mechanism. Specifically, the grinding process is performed by pressing the lapping platen from the top and bottom on both main surfaces of the glass blanks, supplying a grinding liquid containing free abrasive grains onto the main surface of the plate glass, and moving these relatively. Can be adopted. By this grinding process, glass blanks having a flat main surface can be obtained.
  • the glass blanks that have undergone the grinding process can employ a process of polishing the inner peripheral end face and the outer peripheral end face before the first polishing process.
  • the inner peripheral polishing step is a step of alternately laminating glass blanks and spacers one by one to create a laminate, and polishing the inner peripheral end surface with an inner peripheral end surface polishing machine.
  • the spacer is not particularly limited.
  • a spacer made of polypropylene having a thickness of 0.3 mm, an inner diameter of 21 mm, and an outer diameter of 64 mm can be employed.
  • nylon fibers having a diameter of 0.2 mm can be used for the brush bristles of the polishing machine.
  • the number of rotations of the rotating brush can be set to 10,000 rpm, for example.
  • As the polishing liquid for inner circumference polishing for example, a polishing liquid containing a hydrofluoric acid solvent can be used, and as the polishing agent, for example, cerium oxide having an average primary particle diameter of 3 ⁇ m can be used.
  • the outer peripheral polishing step is a step of alternately laminating glass blanks and spacers one by one to create a laminate, and polishing the outer peripheral end surface with an outer peripheral end surface polishing machine.
  • the polishing conditions of the spacer and the polishing machine used are the same as those used in the inner peripheral polishing step.
  • First polishing step (rough polishing step)>
  • both main surfaces of the glass blanks (glass substrate) are polished with an abrasive slurry so that the final surface roughness required in the second polishing step (precision polishing step) described later can be efficiently obtained.
  • polishing pad to be used when the hardness of the polishing pad decreases due to heat generated by polishing, the change in the shape of the polishing surface increases, so that a hard pad can be used, for example, urethane foam can be used.
  • a hard pad for example, urethane foam
  • the polishing liquid cerium oxide having an average primary particle diameter of 0.6 to 2.5 ⁇ m can be used, and a slurry obtained by dispersing cerium oxide in a solvent can be used. It does not specifically limit as a solvent, Water can be employ
  • the mixing ratio of the solvent and cerium oxide is about 1: 9 to 3: 7.
  • the polishing pad tends to fail to polish both main surfaces well.
  • the polishing pad may deteriorate the flatness of the end face or generate scratches.
  • the addition amount of the abrasive slurry is not particularly limited, and is, for example, 1000 to 9000 mL / min.
  • the amount of polishing of the glass substrate in the first polishing step can be, for example, about 25 to 40 ⁇ m.
  • the polishing amount of the glass substrate is less than 25 ⁇ m, scratches and defects tend not to be sufficiently removed.
  • the polishing amount of the glass substrate exceeds 40 ⁇ m, the glass substrate is polished more than necessary, and the production efficiency tends to decrease.
  • the glass substrate that has undergone the first polishing step is preferably washed with a neutral detergent, pure water, isopropyl alcohol (IPA), or the like.
  • a neutral detergent pure water, isopropyl alcohol (IPA), or the like.
  • the glass substrate that has undergone the first polishing step can be subjected to a chemical strengthening step before the second polishing step.
  • the chemical strengthening step is a step of immersing the glass substrate in a strengthening treatment solution to improve the impact resistance, vibration resistance, heat resistance, and the like of the glass substrate.
  • the chemical strengthening step is a step of chemically strengthening the glass substrate.
  • the strengthening treatment liquid used for chemical strengthening include a mixed solution of potassium nitrate (60%) and sodium nitrate (40%).
  • Chemical strengthening can be performed by heating the strengthening treatment liquid to 300 to 400 ° C., preheating the glass substrate to 200 to 300 ° C., and immersing in the strengthening treatment liquid for 3 to 4 hours. During the immersion, the glass substrates can be stored in a holder that holds the end surfaces of the plurality of glass substrates so that both the main surfaces of the glass substrates are chemically strengthened.
  • a standby process for waiting the glass substrate in the air and a water immersion process are adopted to remove the strengthening treatment liquid adhering to the surface of the glass substrate and to homogenize the surface of the glass substrate. be able to.
  • the chemically strengthened layer is formed uniformly, the compressive strain is uniform, deformation is difficult to occur, the flatness is good, and the mechanical strength is also good.
  • the waiting time and the water temperature in the water soaking process are not particularly limited, and can be, for example, kept in the air for 1 to 60 seconds and soaked in water at about 35 to 100 ° C., and may be appropriately determined in consideration of production efficiency.
  • the second polishing step is a step of polishing both main surfaces of the glass substrate more precisely.
  • a double-side polishing machine similar to the double-side polishing machine used in the first polishing step can be used.
  • a soft pad having a hardness lower than that of the polishing pad used in the first polishing step can be used.
  • urethane foam or suede can be used.
  • the same slurry containing cerium oxide or the like as in the first polishing step can be used.
  • an abrasive slurry having a finer grain size and less variation can be used.
  • a slurry prepared by dispersing colloidal silica having an average particle diameter of 20 to 80 nm in a solvent and using it as a slurry can be used. It does not specifically limit as a solvent, Water can be employ
  • a surfactant or a dispersant can be added to these solvents.
  • the mixing ratio of the solvent and colloidal silica can be about 1: 9 to 3: 7.
  • the addition amount of the abrasive slurry is not particularly limited, and can be, for example, 100 to 600 mL / min.
  • the polishing amount in the precision polishing step can be about 2 to 5 ⁇ m.
  • the obtained glass substrate can remove fine defects such as minute roughness and waviness generated on the surface of the glass substrate, or minute scratches generated in the previous process. Is done.
  • the glass substrate manufacturing method of the present embodiment can improve the flatness of the obtained glass substrate, and can manufacture a glass substrate on which the magnetic head can float more stably in the end region. .
  • the flatness of both main surfaces of the glass substrate can be reduced to 3 ⁇ m or less, and the surface roughness Ra of both main surfaces of the glass substrate can be reduced to 0.1 nm.
  • the final cleaning step is a step of cleaning the glass substrate.
  • the cleaning method is not particularly limited, and any cleaning method may be used as long as it can clean the surface of the glass substrate after the precision polishing step. In the present embodiment, scrub cleaning can be employed.
  • the drying step is a step of drying the surface of the glass substrate after removing the cleaning liquid remaining on the surface of the glass substrate by IPA or the like. For example, a water rinse cleaning process is performed on the glass substrate after scrub cleaning for 2 minutes to remove the cleaning liquid residue. Next, an IPA cleaning process is performed for 2 minutes, and water remaining on the surface of the glass substrate is removed by IPA. Finally, the IPA vapor drying step is performed for 2 minutes, and the liquid IPA adhering to the surface of the glass substrate is dried while being removed by the IPA vapor.
  • the glass substrate drying step is not particularly limited, and a known drying method such as spin drying or air knife drying may be employed.
  • the inspection step is a step of inspecting the glass substrate for the presence or absence of scratches, cracks, adhesion of foreign matters, and the like.
  • the inspection can be performed visually or using an optical surface analyzer (for example, “OSA6300” manufactured by KLA-TENCOL).
  • OSA6300 manufactured by KLA-TENCOL
  • the glass substrate can be stored in a dedicated storage cassette in a clean environment so that foreign matter or the like does not adhere to the surface, and can be shipped after vacuum packing.
  • a magnetic film formation process is a process of forming a magnetic film on a glass substrate using a vapor deposition apparatus.
  • the method for forming the magnetic film is not particularly limited, and a conventionally known method can be employed.
  • a method of forming a thermosetting resin in which magnetic particles are dispersed by spin coating on a substrate, or a method of forming by sputtering or electroless plating can be employed.
  • the film thickness by spin coating is about 0.3 to 1.2 ⁇ m
  • the film thickness by sputtering is about 0.04 to 0.08 ⁇ m
  • the film thickness by electroless plating is 0.05 to 0.1 ⁇ m. Degree.
  • the glass substrate is held at about 250 to 350 ° C.
  • the magnetic material used for the magnetic film is not particularly limited, and a conventionally known magnetic material can be used.
  • a Co-based alloy based on Co having a high crystal anisotropy and added with Ni or Cr for the purpose of adjusting the residual magnetic flux density.
  • an alloy composed of a transition metal element and a noble metal element such as a Co—Pt alloy, which includes a transition metal element (Co) and a noble metal element (Pt). Alloys having substantially the same atomic content, or Co— in which the atomic content of the transition metal element (Co) and the noble metal element (Pt) is substantially equal, and the atomic content of Ni is 0.1% or more and 50% or less.
  • a soft magnetic layer (a material having a small coercive force, a Co-based amorphous material, etc.) is preferably laminated below the thin film.
  • a soft magnetic layer a material having a small coercive force, a Co-based amorphous material, etc.
  • a thin film containing an Fe—Pt alloy and Cu oxide is used will be described.
  • a thin film containing an Fe—Pt alloy and Cu oxide is formed by a sputtering method, for example, it can be produced by co-sputtering film formation using Fe, Pt and Cu oxide as targets.
  • a sputtering film may be formed using an Fe—Pt alloy as a target.
  • the composition ratio of Fe—Pt is easily fixed.
  • the Cu oxide is not particularly limited as long as it is an oxide of Cu, and CuO, CuO 2 , or a mixture thereof can be used.
  • the method of adding Cu oxide is not particularly limited, and for example, sputtering film formation may be performed using a material mixed with Cu oxide in advance as a target, or simultaneous sputtering film formation with another target using Cu oxide as a target. May be.
  • the Cu content is preferably an amount that is 10% by volume or more and 20% by volume or less in terms of CuO with respect to the total amount of the Fe—Pt alloy and the Cu oxide.
  • the glass substrate after film formation is heated.
  • the thin film can function as a magnetic recording layer.
  • the heating rate in the heating step is preferably 30 ° C./second or more, more preferably 50 ° C./second or more. When the heating rate is increased, the coercive force tends to decrease.
  • the heating method in the heating process is not particularly limited.
  • An example of the heating method is infrared heating.
  • the glass substrate is preferably held for a predetermined time after being heated to 550 to 650 ° C., for example.
  • the holding time is, for example, 15 minutes to 1 hour.
  • the curvature of glass blanks is reduced in a heat treatment process, and a glass substrate with high shape quality is obtained.
  • the glass substrate obtained according to the present embodiment is less likely to be distorted or cracked even when heated to a high temperature when the magnetic film is formed by the heat assist method.
  • the glass substrate manufacturing method of the present embodiment is useful for producing a large-capacity medium.
  • a magnetic film can be formed on the glass substrate.
  • the surface of the magnetic film may be coated with a lubricant.
  • the magnetic film may be provided with an underlayer or a protective layer. The underlayer and the protective layer are selected according to the type of the magnetic film.
  • the grinding process is sequentially performed by dividing it into two processes, or the chemical strengthening process is performed after any of the coring process, the grinding process, the first polishing process, and the precision polishing process.
  • the design may be changed as appropriate.
  • the glass substrate may be subjected to a hydrogen fluoride immersion treatment as an edge mitigation treatment for scratches generated on the glass substrate.
  • the shape quality of the glass substrate obtained is high, and the manufacturing method of the glass substrate which can be used for a high capacity
  • a method for producing a glass substrate according to one aspect of the present invention is a method for producing a glass substrate having a recording density of 500 GB / sheet or more, and a glass melting step for melting a glass material, and forming glass blanks by forming molten glass And a heat treatment step of heat-treating the glass blanks, wherein the heat treatment is performed by sandwiching both main surfaces of the glass blanks with a setter having a surface roughness of 0.1 to 10 ⁇ m. To do.
  • both main surfaces of the glass blanks are sandwiched between setters having a surface roughness of 0.1 to 10 ⁇ m and heat treatment is performed.
  • melting with a glass blank and a setter can be prevented in a heat treatment process, and the shape quality of the glass substrate obtained is improved.
  • Tg of the glass material constituting the glass blanks is 550 ° C. or higher.
  • Tg of the glass material constituting the glass blank is 550 ° C. or higher, it is necessary to perform heat treatment at a high temperature in order to suppress internal distortion.
  • the glass blanks and the setter are hardly fused because the setter has the above-described surface roughness.
  • the present invention is usually easy to fuse with a setter and easily causes internal distortion and undulation, even when a glass substrate is produced using a glass material having a Tg of 550 ° C. or higher. Swelling can be sufficiently suppressed, and a glass substrate having high shape quality can be obtained.
  • the obtained glass substrate for HDD is a glass substrate for HDD used in the HDD for assist recording.
  • the assist recording method requires heat resistance for the glass substrate.
  • the glass blanks and the setter are hardly fused even when heat treatment is performed at a high temperature, a glass material having excellent heat resistance can be used as a raw material.
  • the magnetic film can be formed by the assist recording method, and a large-capacity medium can be manufactured.
  • the method for producing a glass substrate of the present invention will be described in detail with reference to examples.
  • the manufacturing method of the glass substrate of this invention is not limited to the Example shown below at all.
  • a glass substrate was prepared by the following method.
  • Glass melting process As a glass material, 66 mol% SiO 2 , 10 mol% Al 2 O 3 , 7 mol% Li 2 O, 12 mol% Na 2 O, 1 mol% K 2 O, 4 mol% MgO are used. The aluminosilicate glass contained was melted to produce molten glass (Tg: 510 ° C., softening point: 570 ° C., strain point: 470 ° C.).
  • the molten glass was discharged from the melting nozzle at 1300 ° C. With a pair of blades, the molten glass was cut every 10 g to obtain a glass gob. A blade having a V shape in plan view was selected, and the inner angle of the V shape was set to 80 °. An arc shape was used as a planar view shape of the portion where the V-shaped crosses. Molding was performed by press molding, and an upper mold was used in which the glass gob supplied to the center of the lower mold molding surface was opposed to the lower mold. A tungsten-based material having a thermal conductivity of 150 W / m ⁇ K was used for the upper mold and the lower mold. The pressing time was 1 second, and butt molding was performed so that the thickness of the glass blanks after molding was uniform.
  • the holding temperature in the heat treatment step was 530 ° C. (Tg + 20 ° C.).
  • the temperature was held at the holding temperature for 5 hours, and then the temperature was lowered to 470 ° C., which is the strain point, over 20 hours.
  • Both main surfaces of the glass substrate were subjected to rough polishing using a double-side polishing machine (manufactured by Hamai Sangyo Co., Ltd., 16B type).
  • the polishing pad was a urethane foam pad
  • the abrasive grains were cerium oxide abrasive grains having an average primary particle size of 1 ⁇ m
  • the mixing ratio of water and cerium oxide was 80:20.
  • pH was adjusted with the adjustment liquid containing a sulfuric acid.
  • the load was 100 g / cm 2 .
  • the supply amount of the abrasive slurry was 5 to 10 L / min.
  • the glass substrate was scrubbed.
  • a cleaning liquid a liquid obtained by diluting KOH and NaOH mixed at a mass ratio of 1: 1 with ultrapure water (DI water) and adding a nonionic surfactant to enhance the cleaning performance is obtained.
  • DI water ultrapure water
  • the cleaning liquid was supplied by spraying. After scrub cleaning, in order to remove the cleaning liquid remaining on the surface of the glass substrate, a water rinse cleaning process is performed in an ultrasonic bath for 2 minutes, an IPA cleaning process is performed in an ultrasonic bath for 2 minutes, and finally the glass substrate is cleaned with IPA vapor. The surface of was dried.
  • a glass substrate was formed from a Fe—Pt alloy by a sputtering method, and then a heat treatment (600 ° C., 1 hour) was performed to form a magnetic film, thereby producing an assist recording medium.
  • Example 2 A medium on which a glass substrate and a magnetic film were formed was prepared in the same manner as in Example 1 except that the surface roughness of the setter was 1.05 ⁇ m in the heat treatment step.
  • Example 3 A medium having a glass substrate and a magnetic film formed thereon was produced in the same manner as in Example 1 except that the setter surface roughness was 9.82 ⁇ m in the heat treatment step.
  • Example 1 A medium on which a glass substrate and a magnetic film were formed was produced in the same manner as in Example 1 except that the setter had a surface roughness of 0.01 ⁇ m in the heat treatment step.
  • ⁇ Comparative example 2> A medium having a glass substrate and a magnetic film formed thereon was produced by the same method as in Example 1 except that the surface roughness of the setter was changed to 0.09 ⁇ m in the heat treatment step.
  • Example 3 A medium having a glass substrate and a magnetic film formed thereon was produced by the same method as in Example 1 except that the surface roughness of the setter was 10.2 ⁇ m in the heat treatment step.
  • a medium on which a glass substrate and a magnetic film were formed was produced in the same manner as in Example 1 except that the surface roughness of the setter was 100 ⁇ m.
  • Example 4 A medium having a glass substrate and a magnetic film formed thereon was produced in the same manner as in Example 1 except that the temperature lowering time was 5 hours in the heat treatment step.
  • Example 6 In the glass melting step, 67 mol% SiO 2 , 9 mol% Al 2 O 3 , 5 mol% Li 2 O, 12 mol% Na 2 O, 1 mol% K 2 O, 6 mol as a glass material. % Aluminosilicate glass containing MgO is melted to produce molten glass (Tg: 550 ° C., softening point: 610 ° C., strain point: 510 ° C.), and in the heat treatment step, the holding temperature is 570 ° C. (Tg + 20 ° C.).
  • a medium having a glass substrate and a magnetic film formed thereon was prepared in the same manner as in Example 1 except that the temperature was held at the holding temperature for 5 hours, and then the temperature was lowered to 510 ° C., which is the strain point, over 20 hours.
  • Example 7 In the glass melting step, 67 mol% SiO 2 , 10 mol% Al 2 O 3 , 3 mol% Li 2 O, 10 mol% Na 2 O, 1 mol% K 2 O, 9 mol as a glass material % Aluminosilicate glass containing MgO is melted to produce molten glass (Tg: 600 ° C., softening point: 670 ° C., strain point: 560 ° C.), and the holding temperature is 620 ° C. (Tg + 20 ° C.) in the heat treatment step. A medium having a glass substrate and a magnetic film formed thereon was prepared in the same manner as in Example 1 except that the temperature was held at the holding temperature for 5 hours, and then the temperature was lowered to 560 ° C. as the strain point over 20 hours.
  • microwaviness was measured for the glass substrates obtained in Examples 1 to 7 and Comparative Examples 1 to 4, and the obtained media were subjected to an HDD test.
  • the test method is shown below, and the results are shown in Tables 1 to 4.
  • Examples 1 to 3 in which the glass blanks were subjected to heat treatment using a setter having a surface roughness in the range of 0.1 to 10 ⁇ m, the setter having a surface roughness outside the range was used.
  • Comparative Examples 1 to 4 in which the glass blanks were subjected to heat treatment it was found that a glass substrate with a small undulation and high shape quality was obtained.
  • the media in which the magnetic film was formed on the glass substrates obtained in Examples 1 to 3 had a low occurrence frequency of reading errors and hardly caused a subsequent error.
  • a glass substrate that can be used as a medium with a large capacity of, for example, 500 GB / sheet or more can be obtained.
  • Example 4 a glass substrate was produced with a shorter temperature drop time than in Example 2. As shown in Table 2, in Example 4, it was found that, although the temperature drop time was shortened, the fine waviness of the obtained glass substrate can be suppressed, and a glass substrate with high shape quality can be obtained. As a result, it has been found that the media of Example 4 in which the magnetic film is formed can reduce the frequency of occurrence of read errors and can prevent the occurrence of subsequent errors. As a result, it was found that a glass substrate that can be used as a medium with a large capacity of, for example, 500 GB / sheet or more can be obtained.
  • Example 5 a glass substrate was produced at a higher heat treatment temperature than in Example 2. As shown in Table 3, in Example 5, although the heat treatment temperature was set to 50 ° C. higher than Tg, fusion between the glass blanks and the setter can be prevented, micro-waviness can be suppressed, and the shape quality can be suppressed. It was found that a high glass substrate can be obtained. As a result, it was found that the medium of Example 5 on which the magnetic film was formed can reduce the frequency of occurrence of read errors and can prevent the occurrence of subsequent errors. As a result, it was found that a glass substrate that can be used as a medium with a large capacity of, for example, 500 GB / sheet or more can be obtained.
  • Example 6 and Example 7 a glass substrate was produced using a glass material having a Tg higher than that of Example 2.
  • the Tg of the glass material was 550 ° C. or 600 ° C., and although heat treatment higher than that in Example 2 was required, It has been found that a glass substrate with high shape quality can be obtained because fusion with the setter can be prevented, minute waviness can be suppressed. As a result, it was found that the media of Example 6 and Example 7 on which the magnetic film was formed can reduce the frequency of occurrence of read errors and can prevent the occurrence of subsequent errors.
  • Example 6 and Example 7 can withstand high-temperature heat treatment, it was found that the heat assist method can be adopted when forming the magnetic film. As a result, it was found that a glass substrate that can be used as a medium with a large capacity of, for example, 500 GB / sheet or more can be obtained.

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  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
  • Magnetic Record Carriers (AREA)
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JP2016532235A (ja) * 2013-10-31 2016-10-13 ホーヤ ガラスディスク ベトナム Ｉｉ リミテッド 磁気ディスク用ガラス基板、及び、熱アシスト磁気記録用磁気ディスク
WO2017104513A1 (fr) * 2015-12-17 2017-06-22 日本電気硝子株式会社 Procédé de fabrication de substrat de support en verre
KR20170102315A (ko) * 2014-12-31 2017-09-08 코닝 인코포레이티드 유리 제품을 처리하는 방법
CN109415251A (zh) * 2016-06-30 2019-03-01 康宁股份有限公司 具有加工的应力分布的玻璃基制品及其制造方法
US10710920B2 (en) 2014-12-31 2020-07-14 Corning Incorporated Methods for thermally treating glass articles
US20220157340A1 (en) * 2017-09-29 2022-05-19 Hoya Corporation Method for manufacturing ring-shaped glass spacer

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US9728217B2 (en) 2013-10-31 2017-08-08 Hoya Glass Disk Vietnam Ii Ltd. Glass substrate for magnetic disk and magnetic disk for heat assisted magnetic recording
JP2016532235A (ja) * 2013-10-31 2016-10-13 ホーヤ ガラスディスク ベトナム Ｉｉ リミテッド 磁気ディスク用ガラス基板、及び、熱アシスト磁気記録用磁気ディスク
KR102152978B1 (ko) * 2014-12-31 2020-09-08 코닝 인코포레이티드 유리 제품을 처리하는 방법
KR20170102315A (ko) * 2014-12-31 2017-09-08 코닝 인코포레이티드 유리 제품을 처리하는 방법
JP2018505836A (ja) * 2014-12-31 2018-03-01 コーニング インコーポレイテッド ガラス物品の処理方法
US10669196B2 (en) 2014-12-31 2020-06-02 Corning Incorporated Methods for treating glass articles
US10710920B2 (en) 2014-12-31 2020-07-14 Corning Incorporated Methods for thermally treating glass articles
CN108367961A (zh) * 2015-12-17 2018-08-03 日本电气硝子株式会社 支承玻璃基板的制造方法
KR20180095513A (ko) * 2015-12-17 2018-08-27 니폰 덴키 가라스 가부시키가이샤 지지 유리 기판의 제조 방법
JPWO2017104513A1 (ja) * 2015-12-17 2018-10-04 日本電気硝子株式会社 支持ガラス基板の製造方法
KR102588111B1 (ko) 2015-12-17 2023-10-12 니폰 덴키 가라스 가부시키가이샤 지지 유리 기판의 제조 방법
TWI701221B (zh) * 2015-12-17 2020-08-11 日商日本電氣硝子股份有限公司 支持玻璃基板的製造方法及半導體封裝體的製造方法
WO2017104513A1 (fr) * 2015-12-17 2017-06-22 日本電気硝子株式会社 Procédé de fabrication de substrat de support en verre
JP2019524618A (ja) * 2016-06-30 2019-09-05 コーニング インコーポレイテッド 操作された応力分布を有するガラス系物品及びその作製方法
KR20190027369A (ko) * 2016-06-30 2019-03-14 코닝 인코포레이티드 공학적 응력 분포를 갖는 유리계 제품 및 이의 제조 방법
KR102440332B1 (ko) 2016-06-30 2022-09-06 코닝 인코포레이티드 공학적 응력 분포를 갖는 유리계 제품 및 이의 제조 방법
CN109415251A (zh) * 2016-06-30 2019-03-01 康宁股份有限公司 具有加工的应力分布的玻璃基制品及其制造方法
JP7405506B2 (ja) 2016-06-30 2023-12-26 コーニング インコーポレイテッド 操作された応力分布を有するガラス系物品及びその作製方法
US12040183B2 (en) 2016-06-30 2024-07-16 Corning Incorporated Glass-based article with engineered stress distribution and method of making same
US20220157340A1 (en) * 2017-09-29 2022-05-19 Hoya Corporation Method for manufacturing ring-shaped glass spacer
US11705158B2 (en) * 2017-09-29 2023-07-18 Hoya Corporation Method for manufacturing ring-shaped glass spacer

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