JP2006099942A - Manufacturing method and apparatus of glass substrate for magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method and apparatus of a glass substrate for a magnetic recording medium by which dust generation due to contact of a substrate carrier with a rack for holding the substrate carrier can be prevented when the glass substrate is polished and then immersed in a washing liquid to be washed. <P>SOLUTION: In the manufacturing method and apparatus of the glass substrate for the magnetic recording medium, when the glass substrate is polished using abrasive grains and then immersed in the washing liquid to be washed, a member of a fluororesin or an acetal resin is attached to either one contact part of the substrate carrier for washing and the rack for holding the carrier or both contact parts of the carrier and the rack to perform washing treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for manufacturing a glass substrate for a magnetic recording medium. More specifically, the present invention relates to a method for manufacturing a glass substrate for a magnetic recording medium and an apparatus therefor, comprising washing after the glass substrate is polished and before texture treatment.

  A glass substrate for use in a magnetic recording medium such as a hard disk is required to have a high degree of flatness and smoothness. Therefore, the glass substrate is subjected to a process for polishing the surface and a subsequent cleaning process. And the glass substrate for magnetic recording media obtained by this is attached | subjected to the texture process for surface treatment.

  In order to polish the glass substrate surface efficiently, abrasive grains such as cerium oxide and zirconium oxide are used as an abrasive, but there is a problem that these abrasive grains adhere to the glass surface. Therefore, it is necessary to remove the abrasive grains and glass shavings adhering in the polishing step by washing before the texture treatment.

  In the production of a glass substrate for a magnetic recording medium, it is known to wash the glass substrate with an organic acid such as oxalic acid, an aqueous solution of an inorganic acid such as hydrofluoric acid, sulfuric acid, nitric acid, phosphoric acid, hydrochloric acid, or a strong alkaline aqueous solution. (For example, see Patent Documents 1 to 3). Such cleaning generally uses a combination of a substrate carrier made of metal such as stainless steel and a rack for holding the substrate carrier, and a large number (usually about 50 to 100) of substrates are loaded on the substrate carrier. The carrier is suspended and held by a rack for holding it, immersed in a cleaning tank containing a cleaning liquid, and pulled up from the cleaning tank after a certain period of time.

  However, in this case, at the portion where the carrier and the rack are in contact with each other, dust is generated as a result of the metal being rubbed by the contact, which may cause a new surface defect in the substrate obtained after cleaning.

JP 2004-2163 A JP 2000-31336 A JP 2000-30482 A

  The present invention provides a glass substrate for a magnetic recording medium capable of preventing dust generation due to contact between a substrate carrier and a rack for holding the substrate when the glass substrate is polished and then immersed in a cleaning solution for cleaning. It is an object to provide a method and apparatus.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have made fluororesin or acetal resin into the contact portion between the substrate carrier used for immersion cleaning with the cleaning liquid after polishing the glass substrate and the rack for holding it. Based on this finding, it is possible to eliminate the generation of dust caused by rubbing the contact parts directly contacting and rubbing, thereby preventing new defects on the substrate surface. The present invention has been completed.

  Therefore, this invention consists of the following matters, for example.

  [1] When a glass substrate is polished by using abrasive grains and then immersed in a cleaning solution for cleaning, either a cleaning substrate carrier and / or a rack for holding this carrier, and both carriers and racks A method for producing a glass substrate for a magnetic recording medium, wherein a cleaning treatment operation is performed by attaching a member made of a fluororesin or an acetal resin to a contact portion with the magnetic recording medium.

  [2] After polishing a glass substrate with abrasive grains and immersing it in a cleaning solution for cleaning, either or both of a cleaning substrate carrier and a rack for holding the carrier are used. An apparatus for producing a glass substrate for a magnetic recording medium, wherein a member made of a fluororesin or an acetal resin is attached to a contact portion between the rack and the rack.

  According to the present invention, when a glass substrate after polishing is cleaned, dust generation due to contact between a substrate carrier and a rack for holding the substrate carrier is prevented, and a magnetic recording medium without causing new defects on the substrate surface Glass substrates can be manufactured.

  Hereinafter, preferred embodiments of the present invention will be described. However, it is understood that these explanations are intended to specifically describe preferred examples for carrying out the present invention, and are not intended to limit the present invention in any way. I want to be.

  In the present invention, an ordinary plate glass is preferably used as the glass substrate.

  For polishing the surface of the glass substrate, abrasive grains such as cerium oxide, zirconium oxide, aluminum oxide, and silicon oxide can be used as an abrasive. Among these, from the viewpoint of polishing efficiency and the like, it is preferable to use polishing abrasive grains made of cerium oxide. The abrasive is preferably used as a suspension by suspending these abrasive grains in water.

  The polished glass substrate is then subjected to a cleaning process. Cleaning is generally performed using a combination of a substrate carrier made of metal such as stainless steel and a rack for holding the substrate carrier, and a large number (usually about 50 to 100) of substrates are loaded on the substrate carrier. Is suspended by a rack for holding it, immersed in a cleaning tank containing a cleaning liquid, and pulled up from the cleaning tank after a certain period of time.

  FIG. 1 is a schematic plan view showing a state in which a substrate carrier and a rack are used in combination. FIG. 2 is a schematic cross-sectional view showing a state in which the substrate carrier and the rack are used in combination, and the carrier loaded with the substrate is immersed in the cleaning tank. As shown in the figure, and loaded into the substrate carrier 2 to the substrate 1 large number together, which was suspended held by the rack 3 washing, the washing liquid 4 is immersed in the cleaning tank 5 filled, then after a predetermined time It is lifted from the tank and washed. In the present invention, for example, the part where the carrier and the rack are in direct contact is covered with a fluororesin or acetal resin, for example, a tube made of polytetrafluoroethylene or a similar material, or the contact part is covered with fluororesin or By using an acetal resin such as polytetrafluoroethylene or a similar material, the metal parts constituting the carrier and the rack are prevented from coming into direct contact, and the metal is rubbed to generate dust. It prevents it. In this case, the contact portion to which the member made of the polytetrafluoroethylene material is attached is not particularly limited, and may be either the substrate carrier side or the rack side, or both. Also good.

  The following examples further illustrate the present invention.

A substrate for a magnetic recording medium is prepared using amorphous glass having a skeleton component composition of 90% by mass of B ₂ O ₃ + Al ₂ O ₃ + SiO ₂ and a remaining component composition of 7% by mass of Li ₂ O + Na ₂ O + K ₂ O. did.

  First, melting the raw glass having the above composition was press-molded to obtain a disk-shaped sheet glass. An inner diameter hole was formed in the plate glass using a drill. Next, the main surface of the substrate was subjected to two-stage lapping including rough lapping and precision lapping to adjust the thickness of the substrate. Next, a chamfered portion was formed by chamfering the inner peripheral end face and the outer peripheral end face facing the inner diameter hole of the substrate.

  The inner peripheral side end surface and the outer peripheral side end surface of the glass substrate treated as described above were polished into a mirror surface, and then the main surface of the substrate was finally polished into a mirror surface. As the abrasive, an abrasive containing cerium oxide powder (Mirek manufactured by Mitsui Kinzoku Mining Co., Ltd.) was used.

  The obtained substrate and subsequently subjected to brush scrubbing cleaning, and then sulfuric acid, hydrofluoric acid, hydrosilicofluoric acid, subjected to immersion washing with an aqueous solution of oxalic acid or an acid such as nitric acid to remove the deposits on the surface, the magnetic A glass substrate for recording medium was obtained.

  In this case, the immersion washing, as shown in FIG. 2, used in combination with stainless steel substrate carrier and the rack loaded with substrates, hanging to hold the substrate carrier by a rack, washing bath filled with the cleaning fluid And then pulling up after a predetermined time (about 2 minutes), and the contact portion between the substrate carrier and the rack is covered with a polytetrafluoroethylene tube on both the substrate carrier side and the rack side. The degree of occurrence of surface defects on the obtained substrate was compared with the case where no cover was used. In this case, the surface defects were evaluated at slice 10 nm using ODT (Optical Defecttester) RZ3500 manufactured by Hitachi High-Technology Corporation.

  The results are shown below.

No polytetrafluoroethylene covering: ODT P / N = 10.3 / 8.6
With polytetrafluoroethylene covering: ODT P / N = 5.2 / 4.8

  The present invention prevents dust generation in the immersion cleaning with the cleaning liquid after polishing the substrate, and makes it possible to manufacture a glass substrate for a magnetic recording medium without causing new defects on the substrate surface. Useful.

The schematic plan view which shows the state which uses a combination of a substrate carrier and a rack. The schematic cross section which shows the state which used the board | substrate carrier and the rack in combination and the carrier with which the board | substrate was loaded was immersed in the washing tank.

Explanation of symbols

1 substrate 2 substrate carrier 3 rack 4 cleaning solution 5 cleaning tank

Claims (2)

  When a glass substrate is polished with abrasive grains and then immersed in a cleaning solution for cleaning, the substrate carrier for cleaning and the rack for holding this carrier, or the contact between the carrier and the rack A method for producing a glass substrate for a magnetic recording medium, wherein a cleaning treatment operation is performed by attaching a member made of a fluororesin or an acetal resin to the part. After polishing a glass substrate with abrasive grains and immersing it in a cleaning solution for cleaning, either a substrate carrier for cleaning and a rack for holding this carrier or both carriers and racks are used. An apparatus for producing a glass substrate for a magnetic recording medium, wherein a member made of a fluororesin or an acetal resin is attached to the contact portion.

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