WO2014002693A1 - Substrat de verre de milieu d'enregistrement d'informations et procédé de fabrication d'un substrat de verre de milieu d'enregistrement d'informations - Google Patents

Substrat de verre de milieu d'enregistrement d'informations et procédé de fabrication d'un substrat de verre de milieu d'enregistrement d'informations Download PDF

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Publication number
WO2014002693A1
WO2014002693A1 PCT/JP2013/065354 JP2013065354W WO2014002693A1 WO 2014002693 A1 WO2014002693 A1 WO 2014002693A1 JP 2013065354 W JP2013065354 W JP 2013065354W WO 2014002693 A1 WO2014002693 A1 WO 2014002693A1
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Prior art keywords
glass substrate
information recording
recording medium
main surface
minutes
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PCT/JP2013/065354
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English (en)
Japanese (ja)
Inventor
典子 島津
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コニカミノルタ株式会社
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Application filed by コニカミノルタ株式会社 filed Critical コニカミノルタ株式会社
Priority to JP2014522501A priority Critical patent/JP6021911B2/ja
Priority to SG11201408463YA priority patent/SG11201408463YA/en
Priority to MYPI2014703885A priority patent/MY182274A/en
Priority to CN201380034239.4A priority patent/CN104488028B/zh
Publication of WO2014002693A1 publication Critical patent/WO2014002693A1/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
    • 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
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/739—Magnetic recording media substrates
    • G11B5/73911—Inorganic substrates
    • G11B5/73921—Glass or ceramic substrates

Definitions

  • the present invention relates to a glass substrate for information recording medium and a method for producing a glass substrate for information recording medium.
  • an aluminum substrate or a glass substrate is used as an information recording medium (magnetic disk recording medium) used in a computer or the like.
  • a magnetic thin film layer is formed on these substrates, and information is recorded on the magnetic thin film layer by magnetizing the magnetic thin film layer with a magnetic head.
  • HDD hard disk drive
  • one 2.5-inch recording medium has a recording capacity of 500 GB (single-sided 250 GB) and a surface recording density of 600 Gbit / square inch or more. Things are being developed. In such a high recording density recording medium, even when a very smooth glass substrate is used, it can be seen that read errors and / or write errors may occur during data access, and the cause is analyzed. As a result, it turned out that the error was not caused by a conventional head crash.
  • the glass substrate after manufacturing was examined in detail including the surface state, but no defects that would cause read errors and / or write errors were found, and specific solutions were found.
  • the signal-to-noise ratio of the magnetic signal varied, which could cause read errors and / or write errors. Sex was found.
  • such a variation in the signal-to-noise ratio of the magnetic signal is also referred to as a decrease in electromagnetic conversion characteristics (SNR).
  • a glass substrate for a recording medium is once sealed and packaged after being manufactured and then transported, and then taken out and subjected to a step of coating a magnetic layer.
  • the surface condition of the glass substrate may become non-uniform or a small amount of particles may adhere due to differences in conditions during packaging, transportation, and removal.
  • cleaning is performed using a detergent having such a characteristic that the surface is slightly dissolved (see JP-A-2006-127624 (Patent Document 1)).
  • a glass substrate used in a hard disk drive device having a recording density of 600 Gbit / inch 2 or more has no problem in smoothness and cleanliness of the glass substrate itself, but as an information recording medium, electromagnetic conversion is possible. There arises a problem that the characteristic (SNR) is lowered.
  • An object of the present invention is to provide a glass substrate for an information recording medium and a method for producing the glass substrate for an information recording medium that do not cause a decrease in the noise-to-noise ratio (S / N ratio).
  • the glass substrate for an information recording medium based on the present invention is an information recording medium used for an information recording medium in which a magnetic thin film layer is formed on the main surface of the glass substrate and the recording density on the magnetic recording surface is 600 Gbit / square inch or more.
  • the glass substrate for information recording medium is subjected to an alkali treatment in which the glass substrate for information recording medium is immersed in a sodium hydroxide solution at 40 ° C. and pH 11 for 30 minutes,
  • the average value of SiOH / Si on the main surface is 0.20 or more and 0.50 or less.
  • the average value of SiOH / Si on the main surface of the glass substrate when the alkali treatment is performed is 0.20 or more and 0.45 or less.
  • the rate of change of the average value of SiOH / Si on the main surface of the glass substrate after the alkali treatment Is 20% or less.
  • a method for manufacturing a glass substrate for information recording medium according to the present invention is a method for manufacturing a glass substrate for information recording medium according to any one of the above, wherein the polishing step is performed on the main surface of the disk-shaped glass member. After the polishing step, the polished disc-shaped glass member is contacted with 0.1 ppm to 1.4 ppm hydrogen water for 1 to 10 minutes, and then the disc-shaped glass member is adjusted to pH 10.0 to 11.0. After the contact with the alkaline solution of 5 to 20 minutes, the disc-shaped glass member is subjected to a treatment for contacting the organic acid of 0.05 to 0.5% for 5 to 20 minutes, and then a final cleaning step is performed.
  • the polishing step is performed on the main surface of the disk-shaped glass member. After the polishing step, the polished disc-shaped glass member is contacted with 0.1 ppm to 1.4 ppm hydrogen water for 1 to 10 minutes, and then the disc-shaped glass member is adjusted to pH 10.0 to 11.0. After the contact with the alkaline solution of
  • Another method for producing a glass substrate for an information recording medium according to the present invention is a method for producing a glass substrate for an information recording medium according to any one of the above, and a polishing step for the main surface of a disk-shaped glass member After the polishing step, the disk-shaped glass member after polishing is brought into contact with an alkaline solution having a pH of 10.0 to 11.0 for 5 to 20 minutes, and then the disk-shaped glass member is moved to 0.05 to 0. A treatment of contacting 5% organic acid for 5-20 minutes is performed, followed by a final washing step.
  • Another method for producing a glass substrate for an information recording medium according to the present invention is a method for producing a glass substrate for an information recording medium according to any one of the above, and a polishing step for the main surface of a disk-shaped glass member After the polishing step, the polished disc-shaped glass member is contacted with 1.5 ppm of hydrogen water for 3 minutes, and then the polished disc-shaped glass member is alkalinized with a pH of 10.0 to 11.0. A treatment of contacting the solution for 5 to 20 minutes is performed, and then the final cleaning step is performed.
  • the signal-to-noise ratio (S / N ratio) is lowered even when the recording density on the magnetic recording surface is 600 Gbit / square inch or more and the recording density is very high. It is possible to provide a glass substrate for an information recording medium and a method for producing the glass substrate for an information recording medium that do not cause the problem.
  • FIG. 1 is a perspective view of a glass substrate 1G for an information recording medium
  • FIG. 2 is a perspective view of the information recording medium.
  • an information recording medium glass substrate 1G used for the information recording medium 1 (hereinafter referred to as “glass substrate 1G”) has an annular disk shape with a hole 11 formed in the center. ing.
  • the glass substrate 1G has an outer peripheral end face 12, an inner peripheral end face 13, a front main surface 14, and a back main surface 15.
  • amorphous glass or the like is used as the glass substrate 1G.
  • the outer diameter is about 65 mm
  • the inner diameter is about 20 mm
  • the thickness is about 0.8 mm
  • the surface roughness is about 2.0 mm or less.
  • the inch size of the glass substrate 1G is not particularly limited, and various glass substrates 1G of 0.8 inch, 1.0 inch, 1.8 inch, 2.5 inch, and 3.5 inch are manufactured as disks for information recording media. May be.
  • the thickness of the glass substrate 1G is preferably 0.30 mm to 2.2 mm because it is effective against cracking of the glass substrate 1G due to drop impact.
  • the thickness of the glass substrate 1 ⁇ / b> G here means an average value of values measured at some arbitrary points to be pointed on the substrate.
  • a magnetic thin film layer 23 is formed on the front main surface 14 of the glass substrate 1G.
  • the magnetic thin film layer 23 is formed only on the front main surface 14, but it is also possible to provide the magnetic thin film layer 23 on the back main surface 15.
  • a conventionally known method can be used. For example, a method of spin-coating a thermosetting resin in which magnetic particles are dispersed on the glass substrate 1G, a method of forming by sputtering. The method of forming by electroless plating is mentioned.
  • 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. From the viewpoint of thinning and high density, film formation by sputtering and electroless plating is preferable.
  • the magnetic material used for the magnetic thin film layer 23 is not particularly limited, and a conventionally known material can be used. However, in order to obtain a high coercive force, Co having high crystal anisotropy is basically used for the purpose of adjusting the residual magnetic flux density. Co-based alloys to which Ni and Cr are added are suitable. In recent years, FePt-based materials have been used as magnetic layer materials suitable for heat-assisted recording.
  • the surface of the magnetic thin film layer 23 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.
  • the underlayer in the information recording medium 1 is selected according to the magnetic film.
  • 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 underlayer is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are stacked.
  • a multilayer underlayer such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, or NiAl / CrV may be used.
  • Examples of the protective layer for preventing wear and corrosion of the magnetic thin film layer 23 include a Cr layer, a Cr alloy layer, a carbon layer, a hydrogenated carbon layer, a zirconia layer, and a silica layer.
  • the protective layer can be formed continuously with an in-line sputtering apparatus, such as an underlayer and a magnetic film.
  • the protective layer may be a single layer, or may have a multilayer structure composed of the same or different layers.
  • protective layers may be formed on the protective layer or instead of the protective layer.
  • colloidal silica fine particles are dispersed and coated on a Cr layer diluted with an alcohol-based solvent, and then fired to form a silicon oxide (SiO2) layer. May be.
  • the glass substrate 1G for information recording medium is sealed and packaged in a packaging material after manufacture and then taken out from the packaging material and provided with the magnetic thin film layer 23 and the like.
  • a cleaning process is performed with an alkaline solution or the like in order to remove minute particles adhering during packaging and / or transportation, or to eliminate unevenness of the surface state due to different conditions.
  • the main substrate of the glass substrate is used.
  • the recording density on the magnetic recording surface seems to be 600 Gbit / square inch or more. Even when used in an information recording medium having a very high recording density, it is possible to sufficiently suppress a decrease in the signal-to-noise ratio (S / N ratio).
  • FIG. 3 is a flowchart showing a method for manufacturing the glass substrate 1G and the information recording medium 1.
  • step 10 a “glass melting step” of step 10 (hereinafter abbreviated as “S10”, the same applies to step 11 and subsequent steps), the glass material constituting the glass substrate is melted.
  • a glass substrate was produced by pressing the molten glass material using an upper mold and a lower mold.
  • the glass composition used was a general aluminosilicate glass.
  • the method for producing the glass substrate is not limited to molding, and may be cut out from plate glass, which is a known technique, and the glass composition is not limited thereto.
  • both main surfaces of the glass substrate were lapped.
  • This first lapping step was performed using a double-sided lapping device using a planetary gear mechanism. Specifically, the lapping platen was pressed on both surfaces of the glass substrate from above and below, the grinding liquid was supplied onto the main surface of the glass substrate, and these were moved relatively to perform lapping. By this lapping process, a glass substrate having a substantially flat main surface was obtained.
  • a hole was formed in the center of the glass substrate using a cylindrical diamond drill to produce an annular glass substrate.
  • the inner peripheral end surface and the outer peripheral end surface of the glass substrate were ground with a diamond grindstone, and a predetermined chamfering process was performed.
  • the fine uneven shape formed on the main surface in the coring and end face processing in the previous step can be removed in advance. As a result, the polishing time of the main surface in the subsequent process can be shortened.
  • the outer peripheral end surface of the glass substrate was subjected to mirror polishing by brush polishing.
  • a slurry containing general cerium oxide abrasive grains was used as the abrasive grains.
  • the main surface was polished.
  • the first polishing step is mainly intended to correct scratches and warpage remaining on the main surface in the first and second lapping steps (S12, S14) described above.
  • the main surface was polished by a double-side polishing apparatus having a planetary gear mechanism.
  • the abrasive general cerium oxide abrasive grains were used.
  • a surface reinforcing layer was formed on the main surface of the glass substrate 1G.
  • chemical strengthening was performed by bringing the glass substrate 1G into contact with a mixed solution of potassium nitrate (70%) and sodium nitrate (30%) heated to 300 ° C. for about 30 minutes.
  • the lithium ion and sodium ion on the inner peripheral end surface and outer peripheral end surface of the glass substrate are respectively replaced with sodium ions and potassium ions in the chemical strengthening solution, and a compressive stress layer is formed, thereby forming the main surface of the glass substrate and The end face was strengthened.
  • the main surface polishing step was performed in the “second polishing step” of S18.
  • This second polishing step aims to eliminate the fine defects on the main surface that have been generated and remain in the above-described steps and finish it in a mirror shape, to eliminate warpage and finish it to a desired flatness.
  • polishing was performed by a double-side polishing apparatus having a planetary gear mechanism.
  • abrasive colloidal silica having an average particle diameter of about 20 nm was used to obtain a smooth surface.
  • a pretreatment step of S19 is performed to suppress the activity of the surface of the glass substrate against the alkali treatment. Specifically, when an alkali treatment in which the glass substrate for information recording medium is immersed in a sodium hydroxide solution at 40 ° C. and pH 11 for 30 minutes is performed, the average SiOH / Si of the main surfaces 14 and 15 of the glass substrate The pretreatment step is performed so that the value is 0.20 or more and 0.50 or less.
  • the average value of SiOH / Si after the alkali treatment can be lowered by removing in advance the components eluted by the alkali solution present on the glass substrate surface.
  • the magnetic thin film layer Even when the alkali treatment is performed immediately before the provision of the signal, an effect of suppressing a decrease in the signal-to-noise ratio (S / N ratio) can be obtained.
  • the alkaline solution a sodium hydroxide solution or the like is preferably used.
  • the step of contacting with the hydrogen water has a function of reducing the surface charge of the glass substrate. Therefore, deterioration of Ra of the glass substrate in the alkali treatment can be suppressed, and stability of the glass substrate surface with respect to the subsequent alkali treatment can be enhanced.
  • the step of bringing into contact with the organic acid has an effect of smoothing the Ra of the glass substrate deteriorated by being brought into contact with the alkali solution without impairing the stability to the alkali treatment.
  • the concentration of the organic acid is excessively increased or contacted for a long time, Ra is deteriorated.
  • the organic acid for example, ascorbic acid, sulfamic acid and the like are preferably used. Of these, ascorbic acid is preferred.
  • contact with the solution means that the solution may be showered on the surface of the glass substrate, the glass substrate may be immersed in the solution, and the state in contact with the liquid is defined. If it continues for time, it will not specifically limit.
  • the final cleaning process is a process performed at the end of the glass substrate manufacturing process, and includes a drying process as appropriate.
  • the magnetic recording medium after the magnetic thin film layer is provided by the alkali treatment performed immediately before the magnetic thin film layer is provided on the glass substrate for the information recording medium As an index that can sufficiently suppress the decrease in the signal-to-noise ratio (S / N ratio), the average value of SiOH / Si when a specific alkali treatment is applied to the glass substrate is used.
  • the pretreatment step described above is adjusted so as to satisfy the range of the average value of SiOH / Si after alkali treatment in the present invention, thereby determining the glass substrate production conditions.
  • variation in the orientation of the magnetic thin film layer (magnetic layer) which occurs as a result of an increase in the activity of the surface of the glass substrate by the alkali treatment step performed before the application of the magnetic thin film layer, can be reduced.
  • a glass substrate for an information recording medium capable of sufficiently suppressing a decrease in signal-to-noise ratio (S / N ratio) is provided. Can be provided.
  • the manufacturing method of the glass substrate in the present embodiment is configured as described above.
  • the glass substrate 1G shown in FIG. 1 is obtained by using this glass substrate manufacturing method.
  • the information recording medium 1 shown in FIG. 2 is obtained using the glass substrate 1G thus obtained.
  • both main surfaces of the glass substrate 1G are formed of an adhesion layer made of a Cr alloy and a CoFeZr alloy.
  • An information recording medium of a perpendicular magnetic recording system is formed by sequentially forming a soft magnetic layer, an orientation control underlayer made of Ru, a perpendicular magnetic recording layer made of a CoCrPt alloy, a C-based protective layer, and an F-based lubricating layer. To manufacture.
  • This configuration is an example of a configuration of a perpendicular magnetic recording system, and a magnetic layer or the like may be configured as an in-plane information recording medium. Thereafter, the information recording medium 1 is completed by performing a heat treatment step and the like.
  • Example 2 In the method for manufacturing a glass substrate shown in the above embodiment, after performing the “second polishing step”, as a pretreatment step (S19) for suppressing the activity of the surface of the glass substrate 1, Examples 1 to 3 are performed.
  • the glass substrate 1G was manufactured by performing the process shown in FIG.
  • the manufactured glass substrate 1G was subjected to an alkali treatment and then subjected to a magnetic thin film layer forming step to manufacture an information recording medium.
  • the processing shown in Comparative Example 1 to Comparative Example 2 was also performed.
  • Example 1 In Example 1, after performing the “second polishing step”, the glass substrate was rinsed by showering with 1.5 ppm of hydrogen water for 3 minutes. Thereafter, the glass substrate was brought into contact with a sodium hydroxide solution having a pH of 10.5 for 5 minutes, and then the glass substrate was brought into contact with 0.1% ascorbic acid for 15 minutes. Thereafter, the glass substrate was finally cleaned with pure water.
  • Example 2 In Example 2, after performing the “second polishing step”, the glass substrate 1G was rinsed by showering using pure water. Thereafter, the glass substrate 1G was brought into contact with a sodium hydroxide solution having a pH of 10.5 for 5 minutes, and then the glass substrate was brought into contact with 0.1% ascorbic acid for 15 minutes. Thereafter, the glass substrate was washed with pure water.
  • Example 3 In Example 3, after performing the “second polishing step”, the glass substrate was rinsed by showering with 1.5 ppm of hydrogen water for 3 minutes. Thereafter, the glass substrate was brought into contact with a sodium hydroxide solution having a pH of 10.5 for 5 minutes. Thereafter, the glass substrate was washed with pure water.
  • Comparative Example 1 In Comparative Example 1, after performing the “second polishing step”, the glass substrate was brought into contact with 0.1% ascorbic acid for 15 minutes. Thereafter, the glass substrate was washed with pure water.
  • Comparative Example 2 In Comparative Example 2, after the “second polishing step”, the glass substrate 1G was cleaned with pure water.
  • the average value of the SiOH / Si value after alkali treatment at each evaluation point was determined, and the average value of 10 samples was taken as the SiOH / Si value in each example.
  • the rate of change of the value of SiOH / Si is obtained by calculating the rate of change in the value of SiOH / Si after alkali treatment with respect to the value of SiOH / Si before alkali treatment at each measurement point, and then the SiOH / Si at each measurement point.
  • the average value of the rate of change of the values was obtained, and the average value of the 10 samples was taken as the rate of change of the SiOH / Si value in each example.
  • the glass substrate 1G was manufactured with 100 sheets per batch, and the above evaluation was adopted because the variation in evaluation within the same batch was small.
  • an immersion treatment in a running water washing tank was performed for 60 minutes with a sodium hydroxide solution having a pH of 11.5 at 30 ° C.
  • the magnetic thin film layer was formed on the 20 glass substrates 1G by the above-described magnetic thin film layer forming process to obtain an information recording medium, and then the electromagnetic conversion characteristic was evaluated. Specifically, the difference in SNR with respect to the reference information recording medium was obtained.
  • the electromagnetic conversion characteristic evaluation for the information recording medium was performed by examining the recording / reproducing characteristics of the magnetic head. Specifically, the recording was performed by changing the recording frequency to change the recording density, recording the signal, and reading the reproduction output of this signal.
  • the recording density of the information recording medium was 650 Gbit / inch2.
  • the magnetic head a perpendicular recording merge type head in which a single pole head for recording (for recording) and a GMR head (for reproduction) were integrated was used.
  • the evaluation is "A”, if it is -0.11 db--0.20 db, the evaluation is "B”, if it is -0.21--0.30 db, the evaluation is "C”, if it is -0.31 db-
  • the evaluation was “D”.
  • the SNR value here represents a difference with respect to a predetermined reference value.
  • an optical surface analyzer represented by OSA (Optical Surface Analyzer) in which the cleanliness of the glass substrate 1G before the alkali treatment is set to a predetermined detection sensitivity is used. Confirmed by defect inspection. The larger the number of defects such as deposits and / or dents per information recording medium, the better the surface cleanliness, as the defect count value by the optical system surface analyzer is larger.
  • OSA Optical Surface Analyzer
  • FIG. 4 shows the evaluation results in Examples 1 to 3 and Comparative Examples 1 to 2. Specifically, FIG. 4 shows (i) the value of SiOH / Si of the glass substrate after alkali treatment, and (ii) the reference in Examples 1 to 3 and Comparative Examples 1 to 2. SNR value (db) of the information recording medium produced in Examples 1 to 3 and Comparative Examples 1 and 2 expressed as a difference with respect to the information recording medium, (iii) in Examples 1 to 3 and Comparative Examples 1 to 2 (1) Change rate of SiOH / Si of glass substrate before and after alkali treatment, (iv) OSA count value in Examples 1 to 3 and Comparative Examples 1 and 2, (v) Examples 1 to 3 and Comparative Examples 1 to 2 The evaluation of is shown.
  • Example 1 the SiOH / Si value of the glass substrate after the alkali treatment is “0.20”, and (ii) manufactured using the glass substrate manufactured under the conditions of Example 1.
  • the SNR value (db) of the information recording medium expressed as a difference from the reference information recording medium in the glass substrate is “0.12 (db)”, (iii) SiOH / Si of the glass substrate before and after the alkali treatment.
  • the rate of change was “13%” (iv) and the OSA count value was “6”.
  • the evaluation was “A”.
  • Example 2 (i) the SiOH / Si value of the glass substrate after the alkali treatment was “0.46”, and (ii) glass manufactured using the glass substrate manufactured under the conditions of Example 2.
  • the SNR value (db) of the information recording medium expressed as the difference from the reference information recording medium in the substrate is “ ⁇ 0.11 (db)”, (iii) SiOH / Si of the glass substrate before and after the alkali treatment.
  • the rate of change was “17%” (iv) and the OSA count value was “12”.
  • evaluation "B" was obtained.
  • Example 3 (i) the value of SiOH / Si of the glass substrate after the alkali treatment is “0.50”, and (ii) glass manufactured using the glass substrate manufactured under the conditions of Example 3.
  • the SNR value (db) of the information recording medium expressed as the difference from the reference information recording medium in the substrate is “ ⁇ 0.21 (db)”, (iii) SiOH / Si of the glass substrate before and after the alkali treatment.
  • the rate of change was “21%” (iv) and the OSA count value was “9”.
  • the evaluation was “C” although it was inferior to Example 2.
  • Comparative Example 1 (i) the SiOH / Si value of the glass substrate after the alkali treatment is “0.55”, and (ii) glass manufactured using the glass substrate manufactured under the conditions of Comparative Example 1.
  • the SNR value change (db) of the information recording medium expressed as a difference from the reference information recording medium in the substrate is “ ⁇ 0.35 (db)”, (iii) SiOH / Si of the glass substrate before and after the alkali treatment.
  • the rate of change was “21%” (iv) and the OSA count value was “10”.
  • the evaluation was “D”.
  • the glass substrate was manufactured under the condition that the average value of SiOH / Si on the main surface measured using a time-of-flight secondary ion mass spectrometer after alkali treatment was 0.20 or more and 0.46 or less.
  • a substrate is preferably used, and from the viewpoint of evaluation “A” and evaluation “B”, it is more preferable to use a glass substrate manufactured under conditions of 0.20 or more and 0.30 or less.
  • the measured value of OSA representing the cleanliness of the glass substrate surface did not change greatly, and the Ra change value affected the SNR characteristics.
  • the signal-to-noise ratio (S / N ratio) is lowered even when used in a hard disk drive device with a recording density of 600 Gbit / inch 2 or more. It is possible to provide a glass substrate for an information recording medium without any problems.
  • 1 information recording medium 1G glass substrate for information recording medium, 11 holes, 12 outer peripheral end face, 13 inner peripheral end face, 14 front main surface, 15 back main surface, 23 magnetic thin film layer.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Magnetic Record Carriers (AREA)

Abstract

Ce procédé de fabrication d'un substrat de verre de milieu d'enregistrement d'informations est destiné à la fabrication d'un substrat de verre de milieu d'enregistrement d'informations qui comprend une couche de film mince magnétique formée sur la surface primaire du substrat de verre, et qui est utilisé dans les milieux d'enregistrement d'informations ayant une densité d'enregistrement sur la surface d'enregistrement magnétique de 600 Gbit/pouce carré ou plus. Lorsque ledit substrat de verre de milieu d'enregistrement d'informations a subi un traitement par un alcali mettant en jeu une immersion pendant 30 minutes dans une solution d'hydroxyde de sodium à pH 11 à 40°C, la valeur moyenne de SiOH/Si sur la surface primaire du substrat de verre est de 0,20-0,50.
PCT/JP2013/065354 2012-06-29 2013-06-03 Substrat de verre de milieu d'enregistrement d'informations et procédé de fabrication d'un substrat de verre de milieu d'enregistrement d'informations WO2014002693A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
JP2014522501A JP6021911B2 (ja) 2012-06-29 2013-06-03 情報記録媒体用ガラス基板および情報記録媒体用ガラス基板の製造方法
SG11201408463YA SG11201408463YA (en) 2012-06-29 2013-06-03 Glass substrate for information recording medium and method for manufacturing the same
MYPI2014703885A MY182274A (en) 2012-06-29 2013-06-03 Glass substrate for information recording medium and method for manufacturing the same
CN201380034239.4A CN104488028B (zh) 2012-06-29 2013-06-03 信息记录介质用玻璃基板和信息记录介质用玻璃基板的制造方法

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JP2012-147404 2012-06-29
JP2012147404 2012-06-29

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WO2014002693A1 true WO2014002693A1 (fr) 2014-01-03

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CN (1) CN104488028B (fr)
MY (1) MY182274A (fr)
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WO (1) WO2014002693A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
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