WO2013145460A1 - Method for producing hdd glass substrate and hdd glass substrate - Google Patents

Method for producing hdd glass substrate and hdd glass substrate Download PDF

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Publication number
WO2013145460A1
WO2013145460A1 PCT/JP2012/082490 JP2012082490W WO2013145460A1 WO 2013145460 A1 WO2013145460 A1 WO 2013145460A1 JP 2012082490 W JP2012082490 W JP 2012082490W WO 2013145460 A1 WO2013145460 A1 WO 2013145460A1
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Prior art keywords
glass
glass substrate
hdd
platinum
raw material
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PCT/JP2012/082490
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French (fr)
Japanese (ja)
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大士 梶田
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コニカミノルタ株式会社
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Priority to JP2014507329A priority Critical patent/JP6000336B2/en
Publication of WO2013145460A1 publication Critical patent/WO2013145460A1/en

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B3/00—Charging the melting furnaces
    • C03B3/02—Charging the melting furnaces combined with preheating, premelting or pretreating the glass-making ingredients, pellets or cullet
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/167—Means for preventing damage to equipment, e.g. by molten glass, hot gases, batches
    • 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

Definitions

  • the present invention relates to a method for manufacturing a glass substrate for HDD (Hard Disk Drive) and a glass substrate for HDD, and more particularly to a glass substrate used for an HDD having a magnetic head flying height of 3 nm or less and a method for manufacturing the same.
  • HDD Hard Disk Drive
  • Patent Document 1 JP-A-2006-169085 proposes a technique for suppressing the mixing of platinum into the glass material in the crucible.
  • Patent Document 1 proposes a technique for reducing the contact resistance between glass and platinum by reducing the surface roughness of the crucible that contacts the molten glass, thereby preventing the inclusion of platinum. Has been.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2006-169085
  • the present invention has been made in view of the above problems, and a main object thereof is a method for manufacturing a glass substrate for HDD, which can suppress the amount of platinum mixed into the glass substrate and manufacture a high-density glass substrate for HDD. Is to provide.
  • the manufacturing method of the glass substrate for HDD of 1 aspect which concerns on this invention is a manufacturing method of the glass substrate for HDD whose flying height of a magnetic head is 3 nm or less, Comprising: The glass formed with the material containing platinum and fuse
  • the spherical equivalent particle diameter is defined as the diameter of a sphere having the same volume as that of each platinum particle.
  • the manufacturing method of the glass substrate for HDD of the other situation which concerns on this invention is a manufacturing method of the glass substrate for HDD whose flying height of a magnetic head is 3 nm or less, Comprising: The glass formed with the material containing platinum and fuse
  • the glass raw material is heated to 300 ° C. or higher.
  • the glass raw material is preferably melted in the step of heating the glass raw material.
  • the glass substrate for HDD according to the present invention is a glass substrate for HDD of a heat-assisted recording method manufactured by the manufacturing method according to any one of the above aspects.
  • a high-density glass substrate for HDD can be manufactured.
  • FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. It is a flowchart which shows each process of the manufacturing method of the glass substrate for HDD in embodiment. It is a flowchart which shows the detail of the glass melting process shown in FIG. It is sectional drawing of a melting furnace. It is a figure which shows the experimental condition and experimental result of an Example and a comparative example.
  • FIG. 1 is a perspective view showing the hard disk drive 30.
  • the hard disk drive 30 includes the information recording medium 10.
  • the information recording medium 10 is manufactured using the glass substrate 1 manufactured by the method for manufacturing a glass substrate for HDD (hereinafter also simply referred to as a glass substrate) in the embodiment.
  • the hard disk drive 30 includes an information recording medium 10, a housing 20, a head slider 21, a suspension 22, an arm 23, a vertical shaft 24, a voice coil 25, a voice coil motor 26, a clamp member 27, and a fixing screw 28. Is provided.
  • a spindle motor (not shown) is installed on the upper surface of the housing 20.
  • An information recording medium 10 such as a magnetic disk formed by applying a magnetic material to the glass substrate 1 is rotatably fixed to the spindle motor by a clamp member 27 and a fixing screw 28.
  • the information recording medium 10 is rotationally driven by this spindle motor at, for example, several thousand rpm.
  • the information recording medium 10 is manufactured by forming a magnetic recording layer on the glass substrate 1.
  • the arm 23 is attached so as to be swingable around the vertical axis 24.
  • a suspension 22 formed in a leaf spring (cantilever) shape is attached to the tip of the arm 23.
  • a head slider 21 is attached to the tip of the suspension 22 so as to sandwich the information recording medium 10.
  • a voice coil 25 is attached to the opposite side of the arm 23 from the head slider 21.
  • the voice coil 25 is clamped by a magnet (not shown) provided on the housing 20.
  • a voice coil motor 26 is constituted by the voice coil 25 and the magnet.
  • a predetermined current is supplied to the voice coil 25.
  • the arm 23 swings around the vertical axis 24 by the action of electromagnetic force generated by the current flowing through the voice coil 25 and the magnetic field of the magnet.
  • the suspension 22 and the head slider 21 also swing in the direction of the arrow AR1.
  • the head slider 21 reciprocates on the front and back surfaces of the information recording medium 10 in the radial direction of the information recording medium 10.
  • a magnetic head (not shown) provided on the head slider 21 performs a seek operation.
  • the head slider 21 While the seek operation is performed, the head slider 21 receives a levitation force due to the air flow generated as the information recording medium 10 rotates. Due to the balance between the levitation force and the elastic force (pressing force) of the suspension 22, the head slider 21 travels with a constant flying height with respect to the surface of the information recording medium 10. By the traveling, the magnetic head provided on the head slider 21 can record and reproduce information (data) on a predetermined track in the information recording medium 10.
  • the hard disk drive 30 on which the glass substrate 1 is mounted as a part of the members constituting the information recording medium 10 is configured as described above.
  • the flying height at which the magnetic head provided on the head slider 21 floats with respect to the surface of the information recording medium 10 is called flying height.
  • the flying height is 3 nm or less. That is, the distance between the information recording medium 10 in the thickness direction of the information recording medium 10 and the magnetic head when the information recording medium 10 is rotated is 3 nm or less.
  • the glass substrate 1 is required to have a high degree of surface smoothness in order to avoid the occurrence of problems such as read / write errors or head crashes. Therefore, the glass substrate 1 of the present embodiment is manufactured by a manufacturing method described later. As a result, foreign matter on the surface of the glass substrate 1 can be further suppressed as compared with the conventional case, and the read / write characteristics of the hard disk drive 30 can be improved to improve the recording density.
  • FIG. 2 is a plan view showing glass substrate 1 manufactured by the method for manufacturing a glass substrate for HDD according to the present embodiment.
  • 3 is a cross-sectional view taken along the line III-III in FIG.
  • a glass substrate 1 (HDD glass substrate) used as a part of the information recording medium 10 includes a main surface 2, a main surface 3, an inner peripheral end surface 4, a hole 5, and an outer periphery. It has the end surface 6 and is formed in a disk shape as a whole.
  • the holes 5 are provided so as to penetrate the glass substrate 1 from one main surface 2 toward the other main surface 3.
  • a chamfer 7 is formed between the main surface 2 and the inner peripheral end surface 4 and between the main surface 3 and the inner peripheral end surface 4.
  • a chamfered portion 8 is formed between the main surface 2 and the outer peripheral end surface 6 and between the main surface 3 and the outer peripheral end surface 6.
  • the size of the glass substrate 1 is not particularly limited, and may be a small-diameter disk of 3.5 inches, 2.5 inches, 1.8 inches, or less, for example.
  • the thickness of the glass substrate 1 may be as thin as 2 mm, 1 mm, 0.8 mm, 0.635 mm, or less.
  • the thickness of the glass substrate 1 is a value calculated by averaging thickness values measured at a plurality of arbitrary points on the glass substrate 1.
  • FIG. 4 is a flowchart showing each step of the method of manufacturing the glass substrate for HDD in the embodiment.
  • the manufacturing method of the glass substrate 1 for HDD of the present embodiment includes a glass melting step (S10), a forming step (S20), a grinding / polishing step (S30), a cleaning step (S40), A film process (S50) is provided.
  • a glass raw material that is a raw material of the glass substrate 1 is put into a melting furnace heated to 1300 to 1550 ° C., for example, 1400 ° C., and melted, and further clarification and stirring homogenization are performed. It is.
  • the molten glass is cast into a preheated mold and gradually cooled to form a glass block. Subsequently, after being held at a temperature in the vicinity of the glass transition point for 1 to 3 hours, it is gradually cooled to remove strain.
  • the obtained glass block is sliced into a disk shape and cut out using a core drill with concentric inner and outer circumferences.
  • the molten glass may be press-molded and formed into a disk shape.
  • the disk-shaped glass substrate thus obtained is then ground to a predetermined shape in a grinding / polishing step (S30), and then coarsely polished and precisely polished for surface smoothing.
  • the glass substrate Before rough polishing, between rough polishing and precision polishing, or after precision polishing, the glass substrate may be immersed in a mixed solution of potassium nitrate (50 wt%) and sodium nitrate (50 wt%) to perform chemical strengthening. .
  • the chemical strengthening layer may be removed from the main surface of the glass substrate in any polishing process, but in this case as well, the chemical strengthening layer remains on the inner peripheral side and outer peripheral side end faces of the glass substrate.
  • the glass substrate is washed with at least one of water, acid, and alkali in the washing step (S40) to obtain a final glass substrate for HDD.
  • a magnetic recording layer is formed on both main surfaces (or one of the main surfaces) of the glass base plate that has been cleaned.
  • the magnetic recording layer includes, for example, an adhesion layer made of a Cr alloy, a soft magnetic layer made of a CoFeZr alloy, an orientation control underlayer made of Ru, a perpendicular magnetic recording layer made of a CoCrPt alloy, a protective layer made of a C system, and an F system.
  • the lubricating layer to be formed is formed by sequentially forming a film. By forming the magnetic recording layer, the information recording medium 10 shown in FIG. 1 is obtained.
  • FIG. 5 is a flowchart showing details of the glass melting step (S10) shown in FIG.
  • the melting furnace is first heated in step (S11) shown in FIG.
  • a glass raw material is prepared in step (S12).
  • oxides, carbonates, nitrates, hydroxides, and the like corresponding to the raw materials of the respective components constituting the glass substrate 1 are weighed to a desired ratio and sufficiently powdered. It may be a mixed raw material. Alternatively, the glass material may be a glass cullet that is divided into sizes that are easy to handle after the blended raw material is once melted and formed into a plate shape. Subsequently, the glass raw material is heated in step (S13).
  • the heated glass material is charged into the melting furnace in step (S14), and the glass material is melted in the melting furnace in step (S15).
  • FIG. 6 is a cross-sectional view of the melting furnace 100.
  • the melting furnace 100 is formed of platinum or a platinum alloy having chemical stability at a high temperature of 1000 ° C. or higher.
  • the melting furnace 100 is made of a raw material containing platinum.
  • the platinum alloy may be, for example, oxide dispersion strengthened platinum, a Pt—Rh alloy, or the like.
  • a stirring bar for stirring the glass melt may be disposed inside the melting furnace 100.
  • the melting furnace 100 is provided with a heating unit (not shown).
  • the melting furnace 100 may be an electric furnace provided with an electric heater.
  • the glass melt 110 inside the melting furnace 100 is heated to, for example, 1400 ° C. and is in a liquid phase as described above.
  • the glass raw material 200 to be newly melted is put into the melting furnace 100 in which the glass melt 110 is stored.
  • the charged glass raw material 200 is heated in the melting furnace 100, and the glass raw material 200 is melted to become a glass melt 110.
  • the temperature difference between the glass melt 110 and the glass raw material 200 at about 1000 ° C. to 1500 ° C. is large. Therefore, when the glass raw material 200 is introduced into the glass melt 110, the temperature of the glass melt 110 greatly fluctuates, and the temperature of the glass melt 110 in contact with the glass raw material 200 decreases. As the temperature of the glass melt 110 changes, the temperature of the melting furnace 100 itself varies greatly. It is believed that when platinum repeatedly expands and contracts due to the action of thermal stress, wrinkles and deformation occur on the inner surface of the melting furnace 100, and platinum is peeled off from the portion that repeats thermal expansion and contraction.
  • platinum oxide evaporates at the interface between the glass melt 110 and the atmosphere, particularly at the interface between the glass melt 110 and the melting furnace 100, which is unstable in terms of energy, and the platinum oxide vapor is melted into the melting furnace 100. It is believed that it condenses above and then falls and is reduced in the glass melt 110 to a platinum colloid.
  • platinum peeled from the inner surface of the melting furnace 100 or platinum in the form of a platinum colloid is mixed into the glass melt 110, platinum is mixed into the glass substrate 1 obtained by solidifying the glass melt 110 (platinum). Inclusion) occurs. Since platinum mixed in the glass substrate 1 becomes a foreign substance on the surface of the glass substrate 1 and causes deterioration of the surface smoothness, suppression of platinum inclusion is regarded as important.
  • heat is applied in advance to the glass raw material 200 in step (S13) prior to the step (S14) of charging the glass raw material 200 into the melting furnace 100.
  • the glass raw material 200 is heated to a temperature of 100 ° C. or higher and then charged into the melting furnace 100.
  • the glass raw material 200 is heated to 300 ° C. or higher in advance. More desirably, the glass raw material 200 melted before being charged into the melting furnace 100 is charged into the melting furnace 100.
  • the temperature fluctuation of the glass melt 110 when the glass raw material 200 is put into the melting furnace 100 can be suppressed, so that the temperature change of the melting furnace 100 itself can be suppressed.
  • the number of platinum particles having a spherical equivalent particle diameter of 1 ⁇ m or more mixed into the glass after the glass substrate 1 is formed by heating the glass raw material 200 to a temperature of 100 ° C. or higher and then charging it into the melting furnace 100. Can be suppressed to 1 or less per 3 cc of glass.
  • the method of manufacturing the glass substrate 1 according to the present embodiment in which the glass raw material 200 is heated and then introduced into the melting furnace 100, is more effective when used for manufacturing the glass substrate 1 for HDD of the heat-assisted recording method. is there. Since the glass substrate 1 for heat-assisted recording requires high-temperature annealing at the time of film formation, a glass having high heat resistance is required. In a glass having high heat resistance, a higher temperature is required in order for the glass to behave as a liquid, so that high-temperature heating is also required in the glass melting step. Therefore, the manufacturing method of the present embodiment is a more effective manufacturing method for glass with high heat resistance.
  • Example 1-5 and Comparative Example> A glass cullet was prepared as the glass raw material 200, and the glass cullet was heated. In Example 1-5, the glass cullet was heated to 100 ° C., 300 ° C., 500 ° C., 700 ° C., and 1000 ° C., respectively. On the other hand, in the comparative example, the glass cullet was not heated and the room temperature was kept at 25 ° C. Thereafter, the glass cullet was charged into the melting furnace 100 and melted. A platinum furnace was used as the melting furnace 100, and new melting furnaces 100 were prepared for the respective examples and comparative examples. The temperature of the melting furnace was 1400 ° C.
  • Glass gob is obtained by defoaming the melted glass in a clarification tank, homogenizing it to reduce striae in a stirring tank, and then feeding it from a nozzle, and cutting it with a cutting blade (blade) when the glass reaches a certain amount.
  • a total of 10 glass gobs were produced from the glass sampled every 6 hours from the start of charging the glass cullet into the melting furnace 100.
  • the obtained glass gob was polished, and an inspection was performed to confirm the number of platinum particles having a spherical equivalent particle diameter of 1 ⁇ m or more contained in 3 cc of glass with an optical microscope.
  • glass blanks were produced by press-molding the glass gob produced at the same time as the glass gob subjected to the above inspection, and the glass substrate 1 was produced by grinding and polishing the glass blank.
  • the information recording medium 10 having a magnetic recording layer formed on the main surfaces 2 and 3 of the glass substrate 1 is mounted on a hard disk drive 30 having a distance of 3 nm between the magnetic head and the information recording medium 10 and operated for 10 minutes. The number of reading errors was confirmed. After the occurrence of errors, defect analysis was performed on the occurrence locations using a scanning electron microscope (SEM), and the number of occurrences of platinum-induced errors was counted.
  • SEM scanning electron microscope
  • FIG. 7 is a diagram showing experimental conditions and experimental results of Example 1-5 and the comparative example.
  • the glass cullet was not heated and charged into the melting furnace 100 at room temperature, the glass gob was inspected, and as a result, in all 10 samples, platinum having a sphere-equivalent particle diameter of 1 ⁇ m or more was found. Two or more pieces were mixed per 3 cc of glass.
  • the number of platinum particles having a spherical equivalent particle diameter of 1 ⁇ m or more mixed into the glass was 1 or less per 3 cc of glass.
  • platinum having a sphere equivalent particle diameter of 1 ⁇ m or more was not observed in 3 cc of glass, which was particularly good.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Magnetic Record Carriers (AREA)
  • Glass Melting And Manufacturing (AREA)

Abstract

Provided is a method that is for producing an HDD glass substrate and that can suppress the amount of incorporation of platinum in the glass substrate. The method for producing an HDD glass substrate such that the amount of floatation of a magnetic head is no greater than 3 nm is provided with: a step (S11) for heating a melting furnace formed from a material containing platinum; and a step (S14) for introducing a glass starting material to the melting furnace. After forming the glass substrate, the number of instances of platinum having an equivalent spherical particle size of at least 1 μm incorporated into the glass is no greater than one per 3 cc of glass.

Description

ＨＤＤ用ガラス基板の製造方法およびＨＤＤ用ガラス基板Manufacturing method of glass substrate for HDD and glass substrate for HDD
　本発明は、ＨＤＤ（Ｈａｒｄ　Ｄｉｓｋ　Ｄｒｉｖｅ）用のガラス基板の製造方法およびＨＤＤ用ガラス基板に関し、特に、磁気ヘッドの浮上量が３ｎｍ以下であるＨＤＤに用いられるガラス基板およびその製造方法に関する。 The present invention relates to a method for manufacturing a glass substrate for HDD (Hard Disk Drive) and a glass substrate for HDD, and more particularly to a glass substrate used for an HDD having a magnetic head flying height of 3 nm or less and a method for manufacturing the same.
　近年、ＨＤＤの記憶容量の飛躍的な増大に伴い、媒体の１ビットあたりの記録面積を小さくすることが必要不可欠となっている。媒体の記録面積の減少に比例して記録用の磁性粒子サイズも微細化しなければならず、微小領域でのリード／ライト機能を向上するために、磁気ヘッドと媒体との距離がさらに小さくなっている。その結果、媒体に記録されたデータにアクセスする際のリード／ライトエラー、磁気ヘッドが媒体表面に衝突するヘッドクラッシュなどの問題が発生しやすくなっている。そのため、表面平滑性のさらに高いガラス基板を製造することが求められている。 In recent years, with a dramatic increase in the storage capacity of HDDs, it has become essential to reduce the recording area per bit of the medium. In proportion to the reduction in the recording area of the medium, the magnetic particle size for recording must be reduced, and the distance between the magnetic head and the medium is further reduced in order to improve the read / write function in the minute area. Yes. As a result, problems such as read / write errors when accessing data recorded on the medium and head crashes where the magnetic head collides with the medium surface are likely to occur. Therefore, it is required to produce a glass substrate with higher surface smoothness.
　磁気ヘッドと媒体との距離を小さくしたときリード／ライトエラーやヘッドクラッシュが増加する原因を追究したところ、従来は特に大きな問題となっていなかったガラス基板の表面の異物が原因であることが明らかになってきた。その異物を成分分析したところ、白金であることが判明し、ガラスの溶融工程における溶融炉であるるつぼより溶出した白金であることがわかってきた。 When the cause of the increase in read / write errors and head crashes when the distance between the magnetic head and the medium is reduced, it is clear that the cause is a foreign substance on the surface of the glass substrate, which has not been a major problem in the past. It has become. When the foreign matter was subjected to component analysis, it was found to be platinum, and it was found to be platinum eluted from a crucible which is a melting furnace in the glass melting step.
　そこで従来、るつぼ内でのガラス材料中への白金の混入を抑制する技術が提案されている（たとえば、特開２００６－１６９０８５号公報（特許文献１）参照）。特開２００６－１６９０８５号公報（特許文献１）では、溶融ガラスに接触するるつぼの表面粗さを低減することで、ガラスと白金との接触抵抗を低減して、白金の混入を防ぐ技術が提案されている。 Therefore, conventionally, a technique for suppressing the mixing of platinum into the glass material in the crucible has been proposed (see, for example, JP-A-2006-169085 (Patent Document 1)). Japanese Patent Laid-Open No. 2006-169085 (Patent Document 1) proposes a technique for reducing the contact resistance between glass and platinum by reducing the surface roughness of the crucible that contacts the molten glass, thereby preventing the inclusion of platinum. Has been.
特開２００６－１６９０８５号公報JP 2006-169085 A
　しかし、白金または白金合金製の部材の表面を平滑にする処理には手間がかかる。さらに、るつぼを使用するにつれて表面粗さが悪化するため、白金製るつぼの表面粗さを低減した状態を長期に亘って維持することは現実的に不可能である。すなわち、特開２００６－１６９０８５号公報（特許文献１）に記載の技術では、るつぼの使用開始当時は白金の混入を低減する効果が得られるものの、使用開始後すぐに溶融ガラス材料への白金の混入が増加してしまう問題があった。 However, it takes time and effort to smooth the surface of platinum or platinum alloy members. Furthermore, since the surface roughness deteriorates as the crucible is used, it is practically impossible to maintain the reduced surface roughness of the platinum crucible for a long period of time. That is, in the technique described in Japanese Patent Application Laid-Open No. 2006-169085 (Patent Document 1), although the effect of reducing the mixing of platinum can be obtained at the start of crucible use, immediately after the start of use, platinum is added to the molten glass material. There was a problem of increased contamination.
　本発明は上記の課題に鑑みてなされたものであり、その主たる目的は、ガラス基板中への白金の混入量を抑制し高密度のＨＤＤ用ガラス基板を製造できる、ＨＤＤ用ガラス基板の製造方法を提供することである。 The present invention has been made in view of the above problems, and a main object thereof is a method for manufacturing a glass substrate for HDD, which can suppress the amount of platinum mixed into the glass substrate and manufacture a high-density glass substrate for HDD. Is to provide.
　本発明に係る一の局面のＨＤＤ用ガラス基板の製造方法は、磁気ヘッドの浮上量が３ｎｍ以下であるＨＤＤ用ガラス基板の製造方法であって、白金を含む材料により形成され、溶融されたガラス融液を保持する溶融炉を加熱するステップと、ガラス原料を溶融炉に保持されたガラス融液中に投入するステップと、を備え、ガラス基板の成形後において球換算粒子径が１μｍ以上の白金がガラス中へ混入する個数は、ガラス３ｃｃ当たり１個以下である。ここで、球換算粒子径とは、個々の白金粒子の体積と同じ体積を有する球の直径として定義される。 The manufacturing method of the glass substrate for HDD of 1 aspect which concerns on this invention is a manufacturing method of the glass substrate for HDD whose flying height of a magnetic head is 3 nm or less, Comprising: The glass formed with the material containing platinum and fuse | melted Platinum having a step of heating a melting furnace for holding a melt and a step of charging a glass raw material into a glass melt held in the melting furnace, and having a spherical equivalent particle diameter of 1 μm or more after the glass substrate is formed Is 1 or less per 3 cc of glass. Here, the spherical equivalent particle diameter is defined as the diameter of a sphere having the same volume as that of each platinum particle.
　本発明に係る他の局面のＨＤＤ用ガラス基板の製造方法は、磁気ヘッドの浮上量が３ｎｍ以下であるＨＤＤ用ガラス基板の製造方法であって、白金を含む材料により形成され、溶融されたガラス融液を保持する溶融炉を加熱するステップと、ガラス原料を１００℃以上に加熱するステップと、加熱されたガラス原料を溶融炉に保持されたガラス融液中に投入するステップと、を備える。 The manufacturing method of the glass substrate for HDD of the other situation which concerns on this invention is a manufacturing method of the glass substrate for HDD whose flying height of a magnetic head is 3 nm or less, Comprising: The glass formed with the material containing platinum and fuse | melted There are provided a step of heating a melting furnace for holding the melt, a step of heating the glass raw material to 100 ° C. or more, and a step of putting the heated glass raw material into the glass melt held in the melting furnace.
　上記製造方法において好ましくは、ガラス原料を加熱するステップにおいて、ガラス原料を３００℃以上に加熱する。 In the above production method, preferably, in the step of heating the glass raw material, the glass raw material is heated to 300 ° C. or higher.
　上記製造方法において好ましくは、ガラス原料を加熱するステップにおいて、ガラス原料を溶融させる。 In the above manufacturing method, the glass raw material is preferably melted in the step of heating the glass raw material.
　本発明に係るＨＤＤ用ガラス基板は、上記のいずれかの局面に従った製造方法によって製造された、熱アシスト記録方式のＨＤＤ用ガラス基板である。 The glass substrate for HDD according to the present invention is a glass substrate for HDD of a heat-assisted recording method manufactured by the manufacturing method according to any one of the above aspects.
　本発明のＨＤＤ用ガラス基板の製造方法によると、白金の混入量を抑制できるので、高密度のＨＤＤ用ガラス基板を製造することができる。 According to the method for manufacturing a glass substrate for HDD of the present invention, since the amount of platinum mixed in can be suppressed, a high-density glass substrate for HDD can be manufactured.
実施の形態におけるＨＤＤ用ガラス基板の製造方法によって製造されたガラス基板を備えるＨＤＤを示す斜視図である。It is a perspective view which shows HDD provided with the glass substrate manufactured by the manufacturing method of the glass substrate for HDD in embodiment. 実施の形態におけるＨＤＤ用ガラス基板の製造方法によって製造されたガラス基板を示す平面図である。It is a top view which shows the glass substrate manufactured by the manufacturing method of the glass substrate for HDD in embodiment. 図２中のＩＩＩ－ＩＩＩ線に沿った矢視断面図である。FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. 実施の形態におけるＨＤＤ用ガラス基板の製造方法の各工程を示すフローチャートである。It is a flowchart which shows each process of the manufacturing method of the glass substrate for HDD in embodiment. 図４中に示すガラス溶融工程の詳細を示すフローチャートである。It is a flowchart which shows the detail of the glass melting process shown in FIG. 溶融炉の断面図である。It is sectional drawing of a melting furnace. 実施例および比較例の実験条件および実験結果を示す図である。It is a figure which shows the experimental condition and experimental result of an Example and a comparative example.
　本発明に基づいた実施の形態および実施例について、以下、図面を参照しながら説明する。実施の形態および各実施例の説明において、個数、量などに言及する場合、特に記載がある場合を除き、本発明の範囲は必ずしもその個数、量などに限定されない。実施の形態および各実施例の説明において、同一の部品、相当部品に対しては、同一の参照番号を付し、重複する説明は繰り返さない場合がある。 Embodiments and examples based on the present invention will be described below with reference to the drawings. In the description of the embodiments and the examples, when the number, amount, and the like are referred to, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. In the description of the embodiment and each example, the same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated.
　（ハードディスクドライブ３０）
　図１を参照して、まず、情報記録装置の一例であるハードディスクドライブ３０について説明する。図１は、ハードディスクドライブ３０を示す斜視図である。ハードディスクドライブ３０は、情報記録媒体１０を備える。情報記録媒体１０は、実施の形態におけるＨＤＤ用ガラス基板（以下、単にガラス基板ともいう）の製造方法によって製造されたガラス基板１を用いて、作製される。 (Hard disk drive 30)
With reference to FIG. 1, first, a hard disk drive 30 which is an example of an information recording apparatus will be described. FIG. 1 is a perspective view showing the hard disk drive 30. The hard disk drive 30 includes the information recording medium 10. The information recording medium 10 is manufactured using the glass substrate 1 manufactured by the method for manufacturing a glass substrate for HDD (hereinafter also simply referred to as a glass substrate) in the embodiment.
　具体的には、ハードディスクドライブ３０は、情報記録媒体１０、筐体２０、ヘッドスライダー２１、サスペンション２２、アーム２３、垂直軸２４、ボイスコイル２５、ボイスコイルモーター２６、クランプ部材２７、および固定ネジ２８を備える。筐体２０の上面上には、スピンドルモーター（図示せず）が設置される。 Specifically, the hard disk drive 30 includes an information recording medium 10, a housing 20, a head slider 21, a suspension 22, an arm 23, a vertical shaft 24, a voice coil 25, a voice coil motor 26, a clamp member 27, and a fixing screw 28. Is provided. A spindle motor (not shown) is installed on the upper surface of the housing 20.
　ガラス基板１に磁性体を塗布して形成された磁気ディスクなどの情報記録媒体１０は、クランプ部材２７および固定ネジ２８によって、上記のスピンドルモーターに回転可能に固定される。情報記録媒体１０は、このスピンドルモーターによって、たとえば数千ｒｐｍの回転数で回転駆動される。情報記録媒体１０は、ガラス基板１に磁気記録層が形成されることによって製造される。 An information recording medium 10 such as a magnetic disk formed by applying a magnetic material to the glass substrate 1 is rotatably fixed to the spindle motor by a clamp member 27 and a fixing screw 28. The information recording medium 10 is rotationally driven by this spindle motor at, for example, several thousand rpm. The information recording medium 10 is manufactured by forming a magnetic recording layer on the glass substrate 1.
　アーム２３は、垂直軸２４回りに揺動可能に取り付けられる。アーム２３の先端には、板バネ（片持ち梁）状に形成されたサスペンション２２が取り付けられる。サスペンション２２の先端には、ヘッドスライダー２１が情報記録媒体１０を挟み込むように取り付けられる。 The arm 23 is attached so as to be swingable around the vertical axis 24. A suspension 22 formed in a leaf spring (cantilever) shape is attached to the tip of the arm 23. A head slider 21 is attached to the tip of the suspension 22 so as to sandwich the information recording medium 10.
　アーム２３のヘッドスライダー２１とは反対側には、ボイスコイル２５が取り付けられる。ボイスコイル２５は、筐体２０上に設けられたマグネット（図示せず）によって挟持される。ボイスコイル２５およびこのマグネットにより、ボイスコイルモーター２６が構成される。 A voice coil 25 is attached to the opposite side of the arm 23 from the head slider 21. The voice coil 25 is clamped by a magnet (not shown) provided on the housing 20. A voice coil motor 26 is constituted by the voice coil 25 and the magnet.
　ボイスコイル２５には所定の電流が供給される。アーム２３は、ボイスコイル２５に流れる電流と上記マグネットの磁場とにより発生する電磁力の作用によって、垂直軸２４回りに揺動する。アーム２３の揺動によって、サスペンション２２およびヘッドスライダー２１も矢印ＡＲ１方向に揺動する。ヘッドスライダー２１は、情報記録媒体１０の表面上および裏面上を、情報記録媒体１０の半径方向に往復移動する。ヘッドスライダー２１に設けられた磁気ヘッド（図示せず）はシーク動作を行なう。 A predetermined current is supplied to the voice coil 25. The arm 23 swings around the vertical axis 24 by the action of electromagnetic force generated by the current flowing through the voice coil 25 and the magnetic field of the magnet. As the arm 23 swings, the suspension 22 and the head slider 21 also swing in the direction of the arrow AR1. The head slider 21 reciprocates on the front and back surfaces of the information recording medium 10 in the radial direction of the information recording medium 10. A magnetic head (not shown) provided on the head slider 21 performs a seek operation.
　当該シーク動作が行なわれる一方で、ヘッドスライダー２１は、情報記録媒体１０の回転に伴って発生する空気流により、浮揚力を受ける。当該浮揚力とサスペンション２２の弾性力（押圧力）とのバランスによって、ヘッドスライダー２１は情報記録媒体１０の表面に対して一定の浮上量で走行する。当該走行によって、ヘッドスライダー２１に設けられた磁気ヘッドは、情報記録媒体１０内の所定のトラックに対して情報（データ）の記録および再生を行なうことが可能となる。ガラス基板１が情報記録媒体１０を構成する部材の一部として搭載されるハードディスクドライブ３０は、以上のように構成される。 While the seek operation is performed, the head slider 21 receives a levitation force due to the air flow generated as the information recording medium 10 rotates. Due to the balance between the levitation force and the elastic force (pressing force) of the suspension 22, the head slider 21 travels with a constant flying height with respect to the surface of the information recording medium 10. By the traveling, the magnetic head provided on the head slider 21 can record and reproduce information (data) on a predetermined track in the information recording medium 10. The hard disk drive 30 on which the glass substrate 1 is mounted as a part of the members constituting the information recording medium 10 is configured as described above.
　ヘッドスライダー２１に設けられる磁気ヘッドが情報記録媒体１０の表面に対して浮上する浮上量は、フライングハイトと呼称される。本実施の形態のハードディスクドライブ３０では、フライングハイトは３ｎｍ以下である。すなわち、情報記録媒体１０の回転時における、情報記録媒体１０の厚み方向の情報記録媒体１０と磁気ヘッドとの間隔は、３ｎｍ以下である。 The flying height at which the magnetic head provided on the head slider 21 floats with respect to the surface of the information recording medium 10 is called flying height. In the hard disk drive 30 of the present embodiment, the flying height is 3 nm or less. That is, the distance between the information recording medium 10 in the thickness direction of the information recording medium 10 and the magnetic head when the information recording medium 10 is rotated is 3 nm or less.
　このようにフライングハイトが小さい場合、リード／ライトエラーまたはヘッドクラッシュなどの問題の発生を回避するために、ガラス基板１には高度の表面平滑性が要求される。そこで、本実施の形態のガラス基板１は、後述する製造方法により製造される。これにより、従来と比較してガラス基板１の表面の異物を一層抑制でき、ハードディスクドライブ３０のリード／ライト特性を向上させて記録密度を向上させることが可能になっている。 When the flying height is small in this way, the glass substrate 1 is required to have a high degree of surface smoothness in order to avoid the occurrence of problems such as read / write errors or head crashes. Therefore, the glass substrate 1 of the present embodiment is manufactured by a manufacturing method described later. As a result, foreign matter on the surface of the glass substrate 1 can be further suppressed as compared with the conventional case, and the read / write characteristics of the hard disk drive 30 can be improved to improve the recording density.
　（ガラス基板１）
　図２は、本実施の形態に基づくＨＤＤ用ガラス基板の製造方法によって製造されるガラス基板１を示す平面図である。図３は、図２中のＩＩＩ－ＩＩＩ線に沿った矢視断面図である。 (Glass substrate 1)
FIG. 2 is a plan view showing glass substrate 1 manufactured by the method for manufacturing a glass substrate for HDD according to the present embodiment. 3 is a cross-sectional view taken along the line III-III in FIG.
　図２および図３に示すように、情報記録媒体１０にその一部として用いられるガラス基板１（ＨＤＤ用ガラス基板）は、主表面２、主表面３、内周端面４、孔５、および外周端面６を有し、全体として円盤状に形成される。孔５は、一方の主表面２から他方の主表面３に向かって、ガラス基板１を貫通するように設けられる。主表面２と内周端面４との間、および、主表面３と内周端面４との間には、面取部７がそれぞれ形成される。主表面２と外周端面６との間、および、主表面３と外周端面６との間には、面取部８（チャンファー部）が形成される。 As shown in FIGS. 2 and 3, a glass substrate 1 (HDD glass substrate) used as a part of the information recording medium 10 includes a main surface 2, a main surface 3, an inner peripheral end surface 4, a hole 5, and an outer periphery. It has the end surface 6 and is formed in a disk shape as a whole. The holes 5 are provided so as to penetrate the glass substrate 1 from one main surface 2 toward the other main surface 3. A chamfer 7 is formed between the main surface 2 and the inner peripheral end surface 4 and between the main surface 3 and the inner peripheral end surface 4. Between the main surface 2 and the outer peripheral end surface 6 and between the main surface 3 and the outer peripheral end surface 6, a chamfered portion 8 (chamfer portion) is formed.
　ガラス基板１の大きさは特に限定されず、たとえば３．５インチ、２．５インチ、１．８インチ、またはそれ以下の小径ディスクであってもよい。ガラス基板１の厚さは、２ｍｍ、１ｍｍ、０．８ｍｍ、０．６３５ｍｍ、またはそれ以下の薄型であってもよい。なおガラス基板１の厚さとは、ガラス基板１上の点対象となる任意の複数の点で測定した厚さの値の平均によって算出される値である。 The size of the glass substrate 1 is not particularly limited, and may be a small-diameter disk of 3.5 inches, 2.5 inches, 1.8 inches, or less, for example. The thickness of the glass substrate 1 may be as thin as 2 mm, 1 mm, 0.8 mm, 0.635 mm, or less. The thickness of the glass substrate 1 is a value calculated by averaging thickness values measured at a plurality of arbitrary points on the glass substrate 1.
　（ガラス基板の製造方法）
　次に、本実施の形態におけるガラス基板１（ＨＤＤ用ガラス基板）の製造方法について説明する。図４は、実施の形態におけるＨＤＤ用ガラス基板の製造方法の各工程を示すフローチャートである。図４に示すように、本実施の形態のＨＤＤ用ガラス基板１の製造方法は、ガラス溶融工程（Ｓ１０）、成形工程（Ｓ２０）、研削・研磨工程（Ｓ３０）、洗浄工程（Ｓ４０）および成膜工程（Ｓ５０）を備える。 (Glass substrate manufacturing method)
Next, the manufacturing method of the glass substrate 1 (HDD glass substrate) in this Embodiment is demonstrated. FIG. 4 is a flowchart showing each step of the method of manufacturing the glass substrate for HDD in the embodiment. As shown in FIG. 4, the manufacturing method of the glass substrate 1 for HDD of the present embodiment includes a glass melting step (S10), a forming step (S20), a grinding / polishing step (S30), a cleaning step (S40), A film process (S50) is provided.
　まず、ガラス溶融工程（Ｓ１０）において、ガラス基板１の原料であるガラス原料が、１３００～１５５０℃、たとえば１４００℃に加熱された溶融炉に投入されて溶融され、さらに清澄および撹拌均質化が行なわれる。次に、成形工程（Ｓ２０）において、溶融ガラスが予め加熱された鋳型に鋳込まれ、徐冷してガラスブロックとされる。続いて、ガラス転移点付近の温度で１～３時間保持された後に、徐冷して歪み取りが行なわれる。得られたガラスブロックは、円盤形状にスライスされて、内周および外周を同心円としてコアドリルを用いて切り出される。または、溶融ガラスをプレス成形して円盤状に成形されてもよい。 First, in the glass melting step (S10), a glass raw material that is a raw material of the glass substrate 1 is put into a melting furnace heated to 1300 to 1550 ° C., for example, 1400 ° C., and melted, and further clarification and stirring homogenization are performed. It is. Next, in the forming step (S20), the molten glass is cast into a preheated mold and gradually cooled to form a glass block. Subsequently, after being held at a temperature in the vicinity of the glass transition point for 1 to 3 hours, it is gradually cooled to remove strain. The obtained glass block is sliced into a disk shape and cut out using a core drill with concentric inner and outer circumferences. Alternatively, the molten glass may be press-molded and formed into a disk shape.
　このようにして得られた円盤状のガラス基板は、次に研削・研磨工程（Ｓ３０）において、所定の形状まで研削され、その後表面平滑化のため粗研磨および精密研磨される。粗研磨の前、粗研磨と精密研磨との間、または精密研磨の後に、ガラス基板を硝酸カリウム（５０ｗｔ％）と硝酸ナトリウム（５０ｗｔ％）との混合溶液に浸漬させ、化学強化を行なってもよい。化学強化層は、いずれかの研磨過程においてガラス基板の主表面から除去されてもよいが、この場合でもガラス基板の内周側および外周側端面には引続き化学強化層が残存する。 The disk-shaped glass substrate thus obtained is then ground to a predetermined shape in a grinding / polishing step (S30), and then coarsely polished and precisely polished for surface smoothing. Before rough polishing, between rough polishing and precision polishing, or after precision polishing, the glass substrate may be immersed in a mixed solution of potassium nitrate (50 wt%) and sodium nitrate (50 wt%) to perform chemical strengthening. . The chemical strengthening layer may be removed from the main surface of the glass substrate in any polishing process, but in this case as well, the chemical strengthening layer remains on the inner peripheral side and outer peripheral side end faces of the glass substrate.
　その後ガラス基板は、洗浄工程（Ｓ４０）において、水、酸およびアルカリの少なくとも１つの液で洗浄されて、最終的なＨＤＤ用ガラス基板とされる。さらに成膜工程（Ｓ５０）において、洗浄処理が完了したガラス素板の両主表面（またはいずれか一方の主表面）に対し、磁気記録層が形成される。磁気記録層は、たとえば、Ｃｒ合金からなる密着層、ＣｏＦｅＺｒ合金からなる軟磁性層、Ｒｕからなる配向制御下地層、ＣｏＣｒＰｔ合金からなる垂直磁気記録層、Ｃ系からなる保護層、およびＦ系からなる潤滑層が順次成膜されることによって、形成される。磁気記録層の形成によって、図１に示す情報記録媒体１０が得られる。 Thereafter, the glass substrate is washed with at least one of water, acid, and alkali in the washing step (S40) to obtain a final glass substrate for HDD. Further, in the film forming step (S50), a magnetic recording layer is formed on both main surfaces (or one of the main surfaces) of the glass base plate that has been cleaned. The magnetic recording layer includes, for example, an adhesion layer made of a Cr alloy, a soft magnetic layer made of a CoFeZr alloy, an orientation control underlayer made of Ru, a perpendicular magnetic recording layer made of a CoCrPt alloy, a protective layer made of a C system, and an F system. The lubricating layer to be formed is formed by sequentially forming a film. By forming the magnetic recording layer, the information recording medium 10 shown in FIG. 1 is obtained.
　（ガラス溶融工程の詳細）
　図５は、図４中に示すガラス溶融工程（Ｓ１０）の詳細を示すフローチャートである。本実施の形態における、ガラス原料を溶融するためのガラス溶融工程（Ｓ１０）では、まず図５に示すステップ（Ｓ１１）において、溶融炉を加熱する。 (Details of glass melting process)
FIG. 5 is a flowchart showing details of the glass melting step (S10) shown in FIG. In the glass melting step (S10) for melting the glass raw material in the present embodiment, the melting furnace is first heated in step (S11) shown in FIG.
　ステップ（Ｓ１１）と並行して、ステップ（Ｓ１２）においてガラス原料を準備する。ステップ（Ｓ１２）で準備されるガラス原料２００は、ガラス基板１を構成する各成分の原料として各々相当する酸化物、炭酸塩、硝酸塩、水酸化物などが所望の割合に秤量され粉末で充分に混合された調合原料であってもよい。またはガラス材料は、調合原料が一旦融かされ板状に形成された後に、取り扱い容易な大きさに割られたガラスカレットであってもよい。続いてステップ（Ｓ１３）においてガラス原料を加熱する。 In parallel with step (S11), a glass raw material is prepared in step (S12). In the glass raw material 200 prepared in step (S12), oxides, carbonates, nitrates, hydroxides, and the like corresponding to the raw materials of the respective components constituting the glass substrate 1 are weighed to a desired ratio and sufficiently powdered. It may be a mixed raw material. Alternatively, the glass material may be a glass cullet that is divided into sizes that are easy to handle after the blended raw material is once melted and formed into a plate shape. Subsequently, the glass raw material is heated in step (S13).
　加熱されたガラス原料は、ステップ（Ｓ１４）において溶融炉内に投入され、さらにステップ（Ｓ１５）において溶融炉内でガラス原料が溶融される。 The heated glass material is charged into the melting furnace in step (S14), and the glass material is melted in the melting furnace in step (S15).
　図６は、溶融炉１００の断面図である。溶融炉１００は、１０００℃以上の高温下において化学的安定性を持つ白金または白金合金により形成される。溶融炉１００は、白金を含む原料により形成されている。白金合金は、たとえば酸化物分散強化白金、Ｐｔ－Ｒｈ合金などであってもよい。溶融炉１００の内部に、ガラス融液を撹拌するための撹拌子が配置されてもよい。 FIG. 6 is a cross-sectional view of the melting furnace 100. The melting furnace 100 is formed of platinum or a platinum alloy having chemical stability at a high temperature of 1000 ° C. or higher. The melting furnace 100 is made of a raw material containing platinum. The platinum alloy may be, for example, oxide dispersion strengthened platinum, a Pt—Rh alloy, or the like. A stirring bar for stirring the glass melt may be disposed inside the melting furnace 100.
　溶融炉１００には、図示しない加熱部が設けられている。たとえば溶融炉１００は、電気式のヒータが設けられた電気炉であってもよい。当該加熱部から伝達される熱を受けて、溶融炉１００の内部のガラス融液１１０は、上述した通りたとえば１４００℃に加熱されて液相の状態にある。ガラス融液１１０が貯留された溶融炉１００内に、新たに溶融されるべきガラス原料２００が投入される。投入されたガラス原料２００が溶融炉１００内で加熱され、ガラス原料２００は融解してガラス融液１１０になる。 The melting furnace 100 is provided with a heating unit (not shown). For example, the melting furnace 100 may be an electric furnace provided with an electric heater. In response to the heat transmitted from the heating unit, the glass melt 110 inside the melting furnace 100 is heated to, for example, 1400 ° C. and is in a liquid phase as described above. The glass raw material 200 to be newly melted is put into the melting furnace 100 in which the glass melt 110 is stored. The charged glass raw material 200 is heated in the melting furnace 100, and the glass raw material 200 is melted to become a glass melt 110.
　溶融炉１００に投入されるガラス原料２００の温度が低く室温程度である場合、１０００℃～１５００℃程度のガラス融液１１０とガラス原料２００との温度差が大きいことになる。そのため、ガラス融液１１０にガラス原料２００が投入されると、ガラス融液１１０の温度が大きく変動し、ガラス原料２００の接触するガラス融液１１０の温度が低下する。ガラス融液１１０の温度変化に伴って、溶融炉１００自身の温度も大きく変動する。熱応力の作用により白金が伸縮を繰り返すと、溶融炉１００の内面にシワや変形が発生し、熱伸縮を繰り返す部分より白金の剥離が生じると考えられている。 When the temperature of the glass raw material 200 charged into the melting furnace 100 is low and about room temperature, the temperature difference between the glass melt 110 and the glass raw material 200 at about 1000 ° C. to 1500 ° C. is large. Therefore, when the glass raw material 200 is introduced into the glass melt 110, the temperature of the glass melt 110 greatly fluctuates, and the temperature of the glass melt 110 in contact with the glass raw material 200 decreases. As the temperature of the glass melt 110 changes, the temperature of the melting furnace 100 itself varies greatly. It is believed that when platinum repeatedly expands and contracts due to the action of thermal stress, wrinkles and deformation occur on the inner surface of the melting furnace 100, and platinum is peeled off from the portion that repeats thermal expansion and contraction.
　さらに、ガラス融液１１０と大気との界面、特に、エネルギー的に不安定であるガラス融液１１０と溶融炉１００と大気との界面において、酸化白金が蒸発し、酸化白金の蒸気が溶融炉１００の上方で凝縮し、その後落下してガラス融液１１０中で還元されて白金コロイドになると考えられている。 Furthermore, platinum oxide evaporates at the interface between the glass melt 110 and the atmosphere, particularly at the interface between the glass melt 110 and the melting furnace 100, which is unstable in terms of energy, and the platinum oxide vapor is melted into the melting furnace 100. It is believed that it condenses above and then falls and is reduced in the glass melt 110 to a platinum colloid.
　溶融炉１００の内表面から剥離した白金、または、白金コロイドとなった白金が、ガラス融液１１０に混入すると、ガラス融液１１０を凝固させて得られるガラス基板１中への白金の混入（白金インクルージョン）が発生する。ガラス基板１に混入した白金はガラス基板１の表面の異物となり表面平滑性を悪化させる原因となるので、白金インクルージョンの抑制が重要視されている。 When platinum peeled from the inner surface of the melting furnace 100 or platinum in the form of a platinum colloid is mixed into the glass melt 110, platinum is mixed into the glass substrate 1 obtained by solidifying the glass melt 110 (platinum). Inclusion) occurs. Since platinum mixed in the glass substrate 1 becomes a foreign substance on the surface of the glass substrate 1 and causes deterioration of the surface smoothness, suppression of platinum inclusion is regarded as important.
　そのため、本実施の形態では、溶融炉１００にガラス原料２００を投入するステップ（Ｓ１４）より前のステップ（Ｓ１３）において、ガラス原料２００に予め熱が加えられる。ガラス融液１１０の温度変動を十分に抑制するために、ガラス原料２００は、１００℃以上の温度に加熱されてから溶融炉１００に投入される。望ましくは、ガラス原料２００は予め３００℃以上にまで加熱される。より望ましくは、溶融炉１００に投入される前に溶融されたガラス原料２００が、溶融炉１００に投入される。 Therefore, in the present embodiment, heat is applied in advance to the glass raw material 200 in step (S13) prior to the step (S14) of charging the glass raw material 200 into the melting furnace 100. In order to sufficiently suppress the temperature fluctuation of the glass melt 110, the glass raw material 200 is heated to a temperature of 100 ° C. or higher and then charged into the melting furnace 100. Desirably, the glass raw material 200 is heated to 300 ° C. or higher in advance. More desirably, the glass raw material 200 melted before being charged into the melting furnace 100 is charged into the melting furnace 100.
　このようにすれば、ガラス原料２００を溶融炉１００に投入した際のガラス融液１１０の温度変動を抑制できるので、溶融炉１００自体の温度変化を抑制できる。その結果、溶融炉１００に温度変動が発生して溶融炉１００が熱伸縮することを抑制でき、溶融炉１００の内面からの白金が剥離してガラス融液１１０中に融け出すことを抑制できる。したがって、ガラス融液１１０への白金の混入が抑制され、ガラス基板１での白金インクルージョンの発生を抑制することができる。具体的には、ガラス原料２００を１００℃以上の温度に加熱した後に溶融炉１００に投入することで、ガラス基板１の成形後において球換算粒子径が１μｍ以上の白金がガラス中へ混入する個数を、ガラス３ｃｃ当たり１個以下に抑えることができる。 In this way, the temperature fluctuation of the glass melt 110 when the glass raw material 200 is put into the melting furnace 100 can be suppressed, so that the temperature change of the melting furnace 100 itself can be suppressed. As a result, it is possible to suppress the temperature fluctuation in the melting furnace 100 and to cause the thermal expansion and contraction of the melting furnace 100, and it is possible to suppress the platinum from the inner surface of the melting furnace 100 from peeling and melting into the glass melt 110. Therefore, mixing of platinum into the glass melt 110 is suppressed, and generation of platinum inclusion in the glass substrate 1 can be suppressed. Specifically, the number of platinum particles having a spherical equivalent particle diameter of 1 μm or more mixed into the glass after the glass substrate 1 is formed by heating the glass raw material 200 to a temperature of 100 ° C. or higher and then charging it into the melting furnace 100. Can be suppressed to 1 or less per 3 cc of glass.
　本実施の形態の、ガラス原料２００を加熱してから溶融炉１００に投入するガラス基板１の製造方法は、熱アシスト記録方式のＨＤＤ用のガラス基板１の製造に用いられると、さらに効果的である。熱アシスト記録向けのガラス基板１では成膜時に高温アニール処理が必要になるため、耐熱性の高いガラスが要求される。耐熱性の高いガラスでは、ガラスが液体としての挙動を示すために一層の高温を必要とするので、ガラス溶融工程においても高温加熱が必要になる。そのため、本実施の形態の製造方法は、耐熱性の高いガラスにおいて、さらに有効な製造方法となる。 The method of manufacturing the glass substrate 1 according to the present embodiment, in which the glass raw material 200 is heated and then introduced into the melting furnace 100, is more effective when used for manufacturing the glass substrate 1 for HDD of the heat-assisted recording method. is there. Since the glass substrate 1 for heat-assisted recording requires high-temperature annealing at the time of film formation, a glass having high heat resistance is required. In a glass having high heat resistance, a higher temperature is required in order for the glass to behave as a liquid, so that high-temperature heating is also required in the glass melting step. Therefore, the manufacturing method of the present embodiment is a more effective manufacturing method for glass with high heat resistance.
　以下、実施例を挙げて本発明をより詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
　＜実施例１－５および比較例＞
　ガラス原料２００としてガラスカレットを準備し、ガラスカレットを加熱した。実施例１－５では、ガラスカレットをそれぞれ、１００℃、３００℃、５００℃、７００℃、１０００℃に加熱した。一方、比較例では、ガラスカレットを加熱せず２５℃の室温のままとした。その後、ガラスカレットを、溶融炉１００へ投入し溶融させた。溶融炉１００としては白金炉を使用し、各実施例および比較例に対してそれぞれ新品の溶融炉１００を準備した。溶融炉の温度は１４００℃とした。 <Example 1-5 and Comparative Example>
A glass cullet was prepared as the glass raw material 200, and the glass cullet was heated. In Example 1-5, the glass cullet was heated to 100 ° C., 300 ° C., 500 ° C., 700 ° C., and 1000 ° C., respectively. On the other hand, in the comparative example, the glass cullet was not heated and the room temperature was kept at 25 ° C. Thereafter, the glass cullet was charged into the melting furnace 100 and melted. A platinum furnace was used as the melting furnace 100, and new melting furnaces 100 were prepared for the respective examples and comparative examples. The temperature of the melting furnace was 1400 ° C.
　溶融したガラスを、清澄槽で泡抜きし、撹拌槽で脈理の低減のために均一化し、その後ノズルから送出させ、ガラスが一定量となったところで切断刃（ブレード）で切断することによりガラスゴブを得た。溶融炉１００へのガラスカレットの投入開始時点より６時間ごとにサンプリングしたガラスから、合計１０個のガラスゴブを作製した。得られたガラスゴブを研磨し、ガラス３ｃｃ中に含まれる球換算粒子径が１μｍ以上の白金の個数を光学顕微鏡で確認する検査を行なった。 Glass gob is obtained by defoaming the melted glass in a clarification tank, homogenizing it to reduce striae in a stirring tank, and then feeding it from a nozzle, and cutting it with a cutting blade (blade) when the glass reaches a certain amount. Got. A total of 10 glass gobs were produced from the glass sampled every 6 hours from the start of charging the glass cullet into the melting furnace 100. The obtained glass gob was polished, and an inspection was performed to confirm the number of platinum particles having a spherical equivalent particle diameter of 1 μm or more contained in 3 cc of glass with an optical microscope.
　さらに、上記検査を行なったガラスゴブと同時刻に作製されたガラスゴブをプレス成形することによりガラスブランクスを作製し、ガラスブランクスを研削、研磨加工することでガラス基板１を製造した。そのガラス基板１の主表面２，３に磁気記録層を形成した情報記録媒体１０を、磁気ヘッドと情報記録媒体１０との距離が３ｎｍであるハードディスクドライブ３０に搭載し、１０分間動作させた際の読取りエラー回数の確認を行なった。エラー発生後は、発生箇所について走査型電子顕微鏡（ＳＥＭ）を用いて欠陥解析を行ない、白金起因のエラーの発生数をカウントした。 Furthermore, glass blanks were produced by press-molding the glass gob produced at the same time as the glass gob subjected to the above inspection, and the glass substrate 1 was produced by grinding and polishing the glass blank. When the information recording medium 10 having a magnetic recording layer formed on the main surfaces 2 and 3 of the glass substrate 1 is mounted on a hard disk drive 30 having a distance of 3 nm between the magnetic head and the information recording medium 10 and operated for 10 minutes. The number of reading errors was confirmed. After the occurrence of errors, defect analysis was performed on the occurrence locations using a scanning electron microscope (SEM), and the number of occurrences of platinum-induced errors was counted.
　図７は、実施例１－５および比較例の実験条件および実験結果を示す図である。図７に示すように、ガラスカレットを加熱せず室温のまま溶融炉１００に投入した比較例では、ガラスゴブを検査した結果、１０個のサンプルの全てにおいて、球換算粒子径が１μｍ以上の白金がガラス３ｃｃ当たり２個以上混入していた。一方、ガラスカレットを１００℃以上に加熱した実施例１－５ではいずれも、球換算粒子径が１μｍ以上の白金がガラス中へ混入する個数は、ガラス３ｃｃ当たり１個以下であった。ガラスカレットを３００℃以上に加熱した実施例２－５では、ガラス３ｃｃ中に、球換算粒子径が１μｍ以上の白金は観察されず、特に良好であった。 FIG. 7 is a diagram showing experimental conditions and experimental results of Example 1-5 and the comparative example. As shown in FIG. 7, in the comparative example in which the glass cullet was not heated and charged into the melting furnace 100 at room temperature, the glass gob was inspected, and as a result, in all 10 samples, platinum having a sphere-equivalent particle diameter of 1 μm or more was found. Two or more pieces were mixed per 3 cc of glass. On the other hand, in Examples 1-5 in which the glass cullet was heated to 100 ° C. or higher, the number of platinum particles having a spherical equivalent particle diameter of 1 μm or more mixed into the glass was 1 or less per 3 cc of glass. In Example 2-5 in which the glass cullet was heated to 300 ° C. or higher, platinum having a sphere equivalent particle diameter of 1 μm or more was not observed in 3 cc of glass, which was particularly good.
　ハードディスクドライブ３０の白金起因の読取りエラーの発生回数に関しては、比較例では１０個のサンプルの全てにおいて白金起因の読取りエラーが発生した。一方、実施例１－５では、１０個のサンプルにおいて、白金起因の読取りエラーは発生せず良好であった。 Regarding the number of occurrences of reading errors due to platinum in the hard disk drive 30, in all the 10 samples in the comparative example, reading errors due to platinum occurred. On the other hand, in Example 1-5, the reading error due to platinum did not occur in 10 samples, which was good.
　図７に示す結果から、溶融炉１００に投入する前のガラス原料を１００℃以上に加熱することにより、白金がガラス中へ混入する個数を１個以下に抑制できることが明らかになった。その結果として、ハードディスクドライブ３０に用いられる情報記録媒体１０の表面の異物を低減でき、白金起因のエラーの発生数を低減でき、したがって情報記録媒体１０の記録密度をより大きくできることが明らかになった。 From the results shown in FIG. 7, it was revealed that the number of platinum mixed into the glass can be suppressed to 1 or less by heating the glass raw material before being charged into the melting furnace 100 to 100 ° C. or higher. As a result, it has been clarified that foreign matter on the surface of the information recording medium 10 used in the hard disk drive 30 can be reduced, the number of errors caused by platinum can be reduced, and therefore the recording density of the information recording medium 10 can be increased. .
　以上のように本発明の実施の形態について説明を行なったが、今回開示された実施の形態および実施例はすべての点で例示であって、制限的なものではないと考えられるべきである。この発明の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味、および範囲内でのすべての変更が含まれることが意図される。 As described above, the embodiment of the present invention has been described. However, it should be considered that the embodiment and example disclosed this time are examples in all respects and are not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
　１　ガラス基板、１０　情報記録媒体、３０　ハードディスクドライブ、１００　溶融炉、１１０　ガラス融液、２００　ガラス原料。 1 glass substrate, 10 information recording medium, 30 hard disk drive, 100 melting furnace, 110 glass melt, 200 glass raw material.

Claims (5)

  1. 　磁気ヘッドの浮上量が３ｎｍ以下であるＨＤＤ用ガラス基板の製造方法であって、
    　白金を含む材料により形成され、溶融されたガラス融液を保持する溶融炉を加熱するステップと、
    　ガラス原料を前記溶融炉に保持された前記ガラス融液中に投入するステップと、を備え、
    　ガラス基板の成形後において球換算粒子径が１μｍ以上の白金がガラス中へ混入する個数は、ガラス３ｃｃ当たり１個以下である、ＨＤＤ用ガラス基板の製造方法。     A method for manufacturing a glass substrate for HDD in which the flying height of a magnetic head is 3 nm or less,
    Heating a melting furnace that holds a molten glass melt formed of a material containing platinum;
    Charging the glass raw material into the glass melt held in the melting furnace,
    The method for producing a glass substrate for HDD, wherein the number of platinum particles having a spherical equivalent particle diameter of 1 μm or more mixed into the glass after molding of the glass substrate is 1 or less per 3 cc of glass.
  2. 　磁気ヘッドの浮上量が３ｎｍ以下であるＨＤＤ用ガラス基板の製造方法であって、
    　白金を含む材料により形成され、溶融されたガラス融液を保持する溶融炉を加熱するステップと、
    　ガラス原料を１００℃以上に加熱するステップと、
    　加熱された前記ガラス原料を前記溶融炉に保持された前記ガラス融液中に投入するステップと、を備える、ＨＤＤ用ガラス基板の製造方法。     A method for manufacturing a glass substrate for HDD in which the flying height of a magnetic head is 3 nm or less,
    Heating a melting furnace that holds a molten glass melt formed of a material containing platinum;
    Heating the glass raw material to 100 ° C. or higher;
    Introducing the heated glass raw material into the glass melt held in the melting furnace.
  3. 　前記ガラス原料を加熱するステップにおいて、前記ガラス原料を３００℃以上に加熱する、請求項２に記載のＨＤＤ用ガラス基板の製造方法。 The method for manufacturing a glass substrate for HDD according to claim 2, wherein, in the step of heating the glass raw material, the glass raw material is heated to 300 ° C or higher.
  4. 　前記ガラス原料を加熱するステップにおいて、前記ガラス原料を溶融させる、請求項２または請求項３に記載のＨＤＤ用ガラス基板の製造方法。 4. The method of manufacturing a glass substrate for HDD according to claim 2, wherein the glass raw material is melted in the step of heating the glass raw material.
  5. 　請求項１から請求項４のいずれかに記載の製造方法によって製造された、熱アシスト記録方式のＨＤＤ用ガラス基板である、ＨＤＤ用ガラス基板。 A glass substrate for HDD, which is a glass substrate for HDD of a heat-assisted recording system manufactured by the manufacturing method according to any one of claims 1 to 4.
PCT/JP2012/082490 2012-03-28 2012-12-14 Method for producing hdd glass substrate and hdd glass substrate WO2013145460A1 (en)

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JPH08208239A (en) * 1995-01-25 1996-08-13 Japan Small Corp Glass cullet preheater
JP2007297239A (en) * 2006-04-28 2007-11-15 Tokyo Institute Of Technology Method and apparatus for dissolving glass raw material and glass production apparatus
JP2009161423A (en) * 2007-12-12 2009-07-23 Hoya Corp Method of manufacturing glass substrate for magnetic disk and method of managing melting furnace
JP2010202444A (en) * 2009-03-03 2010-09-16 Asahi Glass Co Ltd Glass melting furnace and glass melting method

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