JP2008246645A - Polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing device capable of preventing foreign matter from being entrapped into a polishing liquid. <P>SOLUTION: An upper surface plate 20 and a lower surface plate 10 vertically hold a polishing workpiece W such as a glass substrate, etc. A polishing liquid supplying part 60 supplies the polishing liquid to the polishing workpiece W. A polishing liquid collecting part 70 to collect the polishing liquid flowing out in the downward direction from the lower surface plate 10 is set below the lower surface plate 10. A polishing liquid circulating part 80 returns the polishing liquid which the polishing liquid collecting part 70 collects to the polishing liquid supplying part 60. It is possible to prevent the foreign matter from being entrapped into the polishing liquid from outside as the polishing liquid supplying part 60 and the polishing liquid collecting part 70 are covered with a cover 90. Additionally, the polishing liquid circulating part 80 is constituted of resin. Consequently, it is possible to prevent growth of the foreign matter in the inside of the polishing device. It is possible to improve an outer appearance yield of the glass substrate after polishing as it is possible to prevent the foreign matter from being entrapped into the polishing liquid from the outside or the inside of the polishing device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing apparatus that holds a workpiece to be polished such as a glass substrate between an upper surface plate and a lower surface plate, and performs polishing while supplying a polishing liquid to the workpiece.

  An aluminum alloy or glass disk is used as a substrate for a magnetic disk recording device used in a computer or the like, for example, a hard disk. A metal magnetic thin film is formed on this substrate, and information is recorded by magnetizing the metal magnetic thin film with a magnetic head.

  Conventionally, aluminum alloys have been mainly used as substrates for magnetic recording media. However, in recent years, magnetic disk recording devices have also been adopted in portable terminals such as notebook computers, and in order to increase the response speed of magnetic disk recording devices, magnetic recording media can be used at 10,000 [rpm] or more. Need to rotate at high speed. For this reason, a substrate for a high-strength magnetic recording medium has been required, and a glass substrate has been used to satisfy these needs. As this glass substrate, an amorphous glass substrate, a crystallized glass substrate, or a chemically strengthened glass substrate is used.

  Here, the manufacturing method of the glass substrate for magnetic recording media which concerns on a prior art (for example, patent document 1) is demonstrated. First, a method for manufacturing an amorphous glass substrate will be described.

  First, a glass material is melted (glass melting process), the molten glass is poured into a planar mold, and the molten glass is sandwiched between the molds to be press-molded to produce a disk-shaped glass substrate (press Molding process). A glass substrate of a semi-finished product that is produced by this press molding process and subjected to the grinding / polishing process described below is referred to as a “blank material”. A circular through hole is formed in the center of the surface of the blank material using a diamond core drill to produce a donut-shaped glass substrate (perforated blank material) (coring step).

  Thereafter, the doughnut-shaped glass substrate (perforated blanks material) is ground by a double-side polishing machine holding a plate on which diamond pellets are attached (first lapping step). In this first lapping step, both surfaces of the perforated blanks are ground and the parallelism, flatness and thickness of the glass substrate are preliminarily adjusted.

  The glass substrate with pre-adjusted parallelism etc. uses electrodeposited diamond, so that the outer peripheral end face and the side surface (inner peripheral end face) of the through hole are ground and chamfered, and the outer diameter and roundness of the glass substrate In addition, the inner diameter and the like are finely adjusted (end face grinding step).

  The glass substrate whose outer diameter is finely adjusted has its inner peripheral end surface and outer peripheral end surface polished, and the end surface is mirrored (end surface polishing step). For example, the end surface is polished by supplying an abrasive to the glass substrate and pressing the end surface of the glass substrate with a predetermined pressure while rotating the nylon brush. By this polishing step, the damage generated by the processing on the inner peripheral end face and the outer peripheral end face is removed, and the inner peripheral end face and the outer peripheral end face are mirror-finished.

  The glass substrate whose end face is polished is ground again on both surfaces, and the parallelism, flatness, and thickness of the glass substrate are finely adjusted (second lapping step). The glass substrate with the finely adjusted parallelism or the like is polished on both surfaces to make the surface unevenness uniform (polishing step). The polished glass substrate is cleaned (cleaning step), further inspected, and a glass substrate that passes the test is used as a substrate for a magnetic recording medium.

  Moreover, when producing a crystallized glass substrate, after an above-mentioned press molding process, an amorphous glass substrate (blanks material) is pinched | interposed with the board | plates made from a ceramic, and it is made to crystallize (crystallization process). After the annealing process, the above-described first lapping process to polishing process are performed.

  Moreover, when producing a chemically strengthened glass substrate, the glass substrate (blanks material) obtained by melting and pressing is subjected to the treatment up to the polishing step, and then mixed with sodium nitrate, potassium nitrate, and the like. By immersing in molten salt, a compressive stress layer is formed on the surface to increase the fracture strength. Thereafter, the cleaning process is performed.

  A magnetic recording medium is produced by laminating a magnetic layer or the like on the surface of the glass substrate produced as described above.

  In the polishing step, a polishing apparatus that uses a glass substrate as a workpiece and polishes both or one side thereof is used. This type of polishing apparatus sandwiches a workpiece to be polished between an upper surface plate and a lower surface plate provided facing each other up and down, and supplies a polishing liquid to the workpiece to be polished. It is constituted so that both sides or one side of a thing may be ground.

  Here, a planetary gear type polishing apparatus (for example, see Patent Document 1) according to the prior art will be described. The planetary gear type polishing apparatus is engaged with the sun gear, the internal gear arranged concentrically on the outer side, the sun gear and the internal gear, and the intersection according to the rotation of the sun gear and / or the internal gear. A rotating carrier, an upper surface plate and a lower surface plate capable of sandwiching the workpiece to be polished held from above and below, and a polishing liquid supply unit for supplying a slurry-like polishing liquid to the workpiece. ing.

  In such a polishing apparatus, a donut-shaped region between the sun gear and the internal gear and sandwiched between the upper surface plate and the lower surface plate is an actual polishing region. The polishing liquid is supplied to this donut-shaped polishing region through a polishing liquid supply hole formed in the upper surface plate. As the polishing liquid, one obtained by dispersing fine polishing particles such as cerium oxide or silica in a liquid such as water or an alkaline solution is used.

  In such a polishing apparatus, since the polishing liquid supplied to the polishing area flows downward from the outer peripheral portion of the lower surface plate, a bowl-shaped polishing liquid recovery unit is disposed below the outer peripheral portion of the lower surface plate. Is being collected. Further, the recovered polishing liquid is sent to the polishing liquid supply path and reused.

  Such a polishing apparatus includes a polishing liquid circulation unit for returning the polishing liquid recovered by the polishing liquid recovery unit to the polishing liquid supply unit. For example, the polishing liquid circulating unit recovers the polishing liquid from the polishing liquid recovery unit via a hose (pipe) and the polishing liquid stored in the tank to the polishing liquid supply unit via the hose (pipe). And a pump for feeding.

JP 2004255553 A

  As described above, in the polishing process, the glass substrate is polished while circulating the polishing liquid between the tank and the polishing portion. As described above, since the tank, the piping, and the polishing processing unit are circulated, there is a possibility that foreign substances such as polishing dust may be mixed in the polishing liquid during that time. When a glass substrate is polished using a polishing liquid in which foreign matters are mixed, there is a possibility that scratches may occur on the surface of the glass substrate or foreign matters may adhere to the surface.

  Conventionally, in order to prevent foreign matter from entering the polishing liquid, the tank is enlarged so that the foreign substance settles and separates from the polishing liquid, a filter that removes the foreign substance from the polishing liquid is installed in the middle of the pipe, A cyclone is installed to separate foreign substances from the polishing liquid.

  However, even if the tank is enlarged and the foreign matter is settled and separated, the fine foreign matter cannot be settled and it is difficult to remove the fine foreign matter. In addition, it is difficult to separate the abrasive particles from the foreign matter and remove only the foreign matter, and there is a problem that the abrasive particles are removed together with the foreign matter.

  In addition, when a filter is used, it is possible to remove foreign matter of 1 [μm] or less by making the filter finer, but abrasive particles are also removed together with the foreign matter. In order to prevent the removal of abrasive particles, if the filter has a coarse mesh, there is a problem that fine foreign matters cannot be removed.

  Further, even when a cyclone is used, it is difficult to separate the abrasive particles from the foreign matter and remove only the foreign matter.

  In either method, it is difficult to separate the abrasive particles from the foreign matter and remove only the foreign matter, and since the abrasive particles are removed together with the foreign matter, it is difficult to efficiently remove only the foreign matter. . If the abrasive particles are removed together with the foreign matter, it is necessary to replenish the polishing liquid with the removed abrasive particles, which is economically problematic.

  The present invention solves the above-described problems, and an object thereof is to provide a polishing apparatus capable of preventing foreign matters from being mixed into the polishing liquid.

According to a first aspect of the present invention, an upper surface plate and a lower surface plate that sandwich and polish a workpiece to be polished from above and below, a polishing liquid supply unit that supplies a polishing liquid to the workpiece, and a lower platen A polishing liquid recovery part for recovering the polishing liquid flowing downward; a polishing liquid circulation part for returning the polishing liquid recovered by the polishing liquid recovery part to the polishing liquid supply part; the polishing liquid supply part and the polishing liquid recovery part; And a covering cover.
According to a second aspect of the present invention, there is provided a polishing apparatus according to the first aspect, wherein the cover further covers the polishing liquid circulating portion.
A third aspect of the present invention is a polishing apparatus according to either the first aspect or the second aspect, wherein an air filter is provided in the cover, and the cover is surrounded by the cover through the air filter. The space is supplied with air from the outside.
According to a fourth aspect of the present invention, there is provided a polishing apparatus according to any one of the first to third aspects, wherein the polishing liquid circulating portion is formed of a resin in a portion in contact with the polishing liquid. It is characterized by being.
According to a fifth aspect of the present invention, there are provided an upper surface plate and a lower surface plate that sandwich and polish a workpiece to be polished from above and below, a polishing liquid supply unit that supplies a polishing liquid to the workpiece, and the lower plate. A polishing liquid recovery part for recovering the polishing liquid flowing down from the board; a polishing liquid circulation part for returning the polishing liquid recovered by the polishing liquid recovery part to the polishing liquid supply part, wherein the part in contact with the polishing liquid is made of resin; A polishing apparatus characterized by comprising:
A sixth aspect of the present invention is the polishing apparatus according to either the fourth aspect or the fifth aspect, wherein the polishing liquid circulation unit recovers the polishing liquid from the polishing liquid recovery part. A tank for storing, and a pipe for supplying the polishing liquid stored in the tank to the polishing liquid supply unit, and an inner surface of the tank and an inner surface of the pipe are made of the resin. It is characterized by that.
The seventh aspect of the present invention is the polishing apparatus according to either the fourth aspect or the fifth aspect, wherein the polishing liquid circulating section is 90% or more of a portion in contact with the polishing liquid. The area is made of resin.

  According to the present invention, since the foreign substance can be prevented from entering the polishing liquid supply part and the polishing liquid recovery part by covering the polishing liquid supply part and the polishing liquid recovery part with the cover. Can be prevented. Thus, by providing a cover in the polishing apparatus, it is possible to prevent foreign matters from entering the polishing liquid from the outside of the polishing apparatus.

  In addition, according to the present invention, in the polishing liquid circulation portion, the portion in contact with the polishing liquid is made of resin, so that the generation of foreign matters in the polishing liquid circulation portion can be suppressed. In this way, by forming the polishing liquid circulating part with resin, it is possible to prevent the generation of foreign matters inside the polishing apparatus and to prevent foreign matters from being mixed into the polishing liquid.

  The polishing apparatus according to the embodiment of the present invention is used for polishing both surfaces of the glass substrate for a magnetic recording medium in the polishing step after the second lapping step. Specifically, the polishing apparatus according to this embodiment is used to polish both surfaces of a glass substrate whose parallelism, flatness, and thickness are finely adjusted by performing the second lapping process. .

[First Embodiment]
The configuration of the polishing apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a polishing apparatus according to the first embodiment of the present invention. The polishing apparatus according to the first embodiment includes a lower surface plate 10, an upper surface plate 20, a sun gear 30, an internal gear 40, a carrier 50, a polishing liquid supply unit 60, a polishing liquid recovery unit 70, and a polishing liquid circulation unit 80. It is prepared for. The lower surface plate 10, the upper surface plate 20, the sun gear 30, the internal gear 40, the carrier 50, and the polishing liquid supply unit 60 constitute a planetary gear type polishing processing unit. Further, a cover 90 is provided so as to cover the polishing portion.

  The lower surface plate 10 is a disk member having an annular horizontal upper surface, and a polishing pad 11 is attached to the upper surface. The lower surface of the lower surface plate 10 is fixed to a lower support member 12 that is rotatable about a vertical axis A (a vertical axis that passes through the center of the polishing portion). The lower support member 12 is linked to the lower surface plate rotation drive unit 13, and the lower surface plate 10 and the lower support member 12 are rotated by the drive.

  The upper surface plate 20 is a disk member having an annular horizontal lower surface, and a polishing pad 21 is bonded to the lower surface facing the lower surface plate 10. The upper surface of the upper surface plate 20 is fixed to an upper support member 22 that can rotate about a vertical axis A. The upper support member 22 is linked to the upper surface plate rotation drive unit 23, and the upper surface plate 20 and the upper support member 22 are rotated by the drive.

  The sun gear 30 is rotatably provided at the center position of the polishing processing unit, and is rotated about the vertical axis A in accordance with the drive of the sun gear rotation drive unit 31. However, when the internal gear 40 is rotated, the sun gear 30 may be fixed so as not to rotate.

  The internal gear 40 is a ring-shaped gear having a tooth row on the inner peripheral side, and is arranged concentrically outside the sun gear 30. In this embodiment, the internal gear 40 is fixed to the internal gear support member 41 with a bolt so as not to rotate. However, the internal gear 40 can rotate about the vertical axis A, and an internal gear rotation drive unit (not shown). ) May be rotated in response to the driving.

  The carrier (planetary gear) 50 is a thin plate-like disk member having a tooth row on the outer peripheral portion, and one or a plurality of workpiece holding holes 50a for holding the workpiece W to be polished are formed. In this embodiment, the glass substrate after the second lapping step is applied as the workpiece W to be polished.

  A plurality of carriers 50 are usually arranged in the polishing portion. These carriers 50 mesh with the sun gear 30 and the internal gear 40, and rotate around the sun gear 30 around the intersection according to the rotation of the sun gear 30 and / or the internal gear 40. That is, the workpiece W held by the carrier 50 is sandwiched between the lower surface plate 10 and the upper surface plate 20, and the carrier 50 is rotated and rotated in this state, whereby the upper and lower surfaces of the workpiece W are polished. Is done.

  In such a polished portion, the outer diameters of the lower surface plate 10 and the upper surface plate 20 are usually smaller than the inner diameter of the internal gear 40, and between the sun gear 30 and the internal gear 40 and the lower surface plate. A donut-shaped region sandwiched between the plate 10 and the upper surface plate 20 is an actual polishing region.

  The polishing liquid supply unit 60 is a tube for supplying a polishing liquid supply rod 61 for storing the polishing liquid, and a polishing liquid stored in the polishing liquid supply rod 61 to a polishing region between the lower surface plate 10 and the upper surface plate 20. 62 is comprised. The polishing liquid supply rod 61 is provided above the upper support member 22 via a plurality of support members 63. Further, the polishing liquid supply rod 61 has an opening at the top, and the polishing liquid is supplied from the opening.

  The upper support member 22, the upper surface plate 20, and the polishing pad 21 are formed with a plurality of through holes 22a, 20a, 21a communicating with each other, and the lower ends of the tubes 62 are connected through the through holes 22a, 20a, 21a. The Thereby, the polishing liquid stored in the polishing liquid supply rod 61 is supplied to the polishing region between the upper surface plate 20 and the lower surface plate 10 through the tube 62 and the through holes 22a, 20a, and 21a.

  As the polishing liquid, a liquid in which fine abrasive particles are dispersed in a liquid is used. As the abrasive particles, for example, silicon carbide, aluminum oxide, cerium oxide, zirconium oxide, manganese oxide, colloidal silica, or the like is used, which is appropriately selected according to the material of the workpiece W, the surface roughness of the workpiece, and the like. . These abrasive particles are dispersed in a liquid such as water, an acidic solution, or an alkaline solution to form a polishing liquid.

  The polishing liquid recovery part 70 is installed below the outer peripheral part of the lower surface plate 10. The polishing liquid supplied from the polishing liquid supply unit 60 to the polishing region flows down from the outer peripheral portion of the lower surface plate 10 and is recovered by the polishing liquid recovery unit 70.

  The polishing liquid recovery unit 70 is, for example, a ring-shaped saddle member having a vertical cross section having a U-shape, a U-shape, a V-shape, and the like, and an opening is formed in the upper portion. It arrange | positions corresponding to the outer peripheral part whole perimeter. Then, the polishing liquid recovery unit 70 receives and stores the polishing liquid flowing down from the lower surface plate 10 through the opening formed in the upper part. One or a plurality of through holes are formed in the bottom of the polishing liquid recovery unit 70 so that the recovered polishing liquid can be taken out through the through holes.

  The polishing liquid circulation unit 80 returns the polishing liquid collected by the polishing liquid collection unit 70 to the polishing liquid supply unit 60. For example, the polishing liquid circulation unit 80 recovers the polishing liquid from the polishing liquid recovery unit 70 via the hose 71 and the polishing liquid stored in the tank 81 via the hose 82. And a pump 83 to be fed to.

  The tank 81 is provided with a cover 84 at the top, and the inside of the tank 81 is sealed by the cover 84. Thereby, it is possible to prevent foreign matter from entering the tank 81 from the outside. The cover 84 is formed with a through hole, and a hose 74 and a hose 82 are installed through the through hole.

  The cover 90 is installed so as to cover the entire polishing processing portion, and the inside of the polishing processing portion is sealed by the cover 90. As a result, it is possible to prevent foreign matter from entering the space where the polishing portion is installed from the outside. The cover 90 is provided with an air filter 91 for taking in outside air. The air filter 91 can supply clean air to the polishing unit. The cover 90 is made of a resin such as acrylic, nylon, or vinyl chloride.

  Further, the cover 90 may be installed so as to cover the entire polishing apparatus including the polishing liquid circulating unit 80. As a result, foreign matters can be prevented from entering the space in which the tank 81 is installed, and foreign matters can be further prevented from entering the tank 81.

  As described above, an opening for receiving the polishing liquid is formed only in the polishing liquid supply unit 60 and the polishing liquid recovery unit 70, and the entire polishing processing unit or the entire polishing apparatus is covered with the cover 90, whereby the polishing liquid It is possible to prevent foreign matter from being mixed in.

  In this way, since it is possible to prevent foreign substances from being mixed into the polishing liquid, it is possible to prevent the occurrence of defects in the glass substrate due to the polishing process and to greatly improve the appearance yield after the polishing is completed.

  Further, since foreign matters can be prevented from entering the polishing liquid from the outside, it is not necessary to provide a filter on the hose 82. As a result, clogging in the filter can be prevented. In addition, since it is not necessary to settle and separate foreign substances in the tank 81, the tank 81 can be reduced in size. As a result, the entire polishing apparatus can be reduced in size.

  Furthermore, since it is not necessary to provide a filter, it is possible to prevent the abrasive particles of the polishing liquid from being removed by the filter. As a result, the replenishment amount of the abrasive particles can be reduced, which is economical.

  When a plurality of polishing apparatuses are installed, each polishing apparatus is covered with a cover 90, and each polishing apparatus is spatially separated. As a result, even if foreign matter is mixed into the cover 90 covering a certain polishing apparatus, and the polishing apparatus is contaminated with foreign matter, each polishing apparatus is covered with the cover 90, Since it is spatially separated from the polishing apparatus, there is an effect that other polishing apparatuses are not contaminated by foreign substances. That is, even if a foreign substance is mixed in the working space of one polishing apparatus, the other polishing apparatus is not affected, and the mixing of the foreign substance into the polishing liquid of the other polishing apparatus can be prevented.

[Second Embodiment]
Next, the configuration of a polishing apparatus according to the second embodiment of the present invention will be described. The polishing apparatus according to the second embodiment is similar to the polishing apparatus according to the first embodiment described above, the lower surface plate 10, the upper surface plate 20, the sun gear 30, the internal gear 40, the carrier 50, and the polishing liquid supply unit 60. The polishing liquid collecting unit 70 and the polishing liquid circulating unit 80 are provided. In the second embodiment, the cover 90 may or may not be provided in the polishing apparatus.

  In the polishing apparatus according to the second embodiment, the polishing liquid circulating unit 80 is made of resin. For example, the tank 81 and the hose 82 of the polishing liquid circulating unit 80 are made of resin. A valve (not shown) installed in the hose 82 is made of resin, and a tube pump (made of resin) is used for the pump 83.

  As for resinization, the entire polishing liquid circulating unit 80 may be made of resin, only the portion in contact with the polishing liquid may be made of resin, and the portion not in contact with the polishing liquid may not be made of resin. . For example, the inner surface of the tank 81 and the inner surface of the hose 82 are made of resin in order to come into contact with the polishing liquid. For example, when the surface of the metal tank 81 is made of resin, or the surface of the metal hose 82 is made of resin, the portion in contact with the polishing liquid is made of resin.

  Examples of the resin used for the polishing liquid circulating unit 80 include fluororesin, vinyl chloride, polyvinyl alcohol (PVA), and urethane. Also, a paint containing resin may be applied to the surface of the tank 81, particularly the inner surface of the tank 81, or the surface of the hose 82, particularly the inner surface of the hose 82.

  As described above, it is possible to suppress the generation of foreign matter from the tank 81, the hose 82, the valve, and the like constituting the polishing liquid circulation unit 80 by configuring the polishing liquid circulation unit 80 with resin. That is, by constituting the polishing liquid circulation part 80 with a resin, it is possible to prevent the glass component in the polishing scraps from adhering to the resin surface and solidifying. When the glass component is solidified, it is considered that when the glass component falls off, it is mixed into the polishing liquid and causes scratches on the glass substrate. In this embodiment, since the polishing liquid circulating unit 80 is made of resin, it is possible to prevent the glass component from solidifying, and thus it is possible to suppress the generation of foreign matters inside the polishing apparatus. Further, even when a paint containing resin is applied to the surface of the tank 81 or the surface of the hose 82, the same operation and effect can be achieved.

  As described above, since foreign substances can be prevented from entering the polishing liquid, as in the first embodiment, the occurrence of defects in the glass substrate due to polishing is prevented, and the appearance yield after polishing is greatly increased. Can be improved. Moreover, since it is not necessary to provide a filter, clogging with the filter can be prevented. Furthermore, since it is not necessary to settle and separate in the tank 81, the tank 81 can be reduced in size, and as a result, the entire polishing apparatus can be reduced in size. Moreover, since it is not necessary to install a filter, the replenishment amount of the abrasive particles can be reduced, which is economical.

  Further, the entire portion of the polishing liquid circulating unit 80 that contacts the polishing liquid may not be made of resin. For example, if 90% or more of the entire surface area of the portion in contact with the polishing liquid in the polishing liquid circulation unit 80 is made of resin, it is possible to suppress the generation of foreign matters from the polishing liquid circulation unit 80.

  Further, if the polishing liquid supply unit 60 and the polishing liquid recovery unit 70 are made of resin, it is possible to further prevent foreign substances from being generated in the polishing apparatus. For example, by forming the polishing liquid supply rod 61 and the tube 62 from resin, it is possible to prevent the generation of foreign matters in the polishing liquid supply unit 60.

  Further, the polishing liquid circulating unit 80 is made of resin, and the entire polishing apparatus is covered with the cover 90 in the same manner as in the first embodiment, thereby preventing the generation of foreign matters in the polishing apparatus and from the outside of the polishing apparatus. Foreign matter can be prevented from being mixed. That is, by covering the polishing processing unit or the entire polishing apparatus with the cover 90, it is possible to prevent foreign matter from entering the polishing liquid from the outside of the polishing apparatus, and further, the polishing liquid circulating unit 80 is made of resin. Further, it is possible to prevent the generation of foreign matter inside the polishing apparatus. As described above, since it is possible to prevent the generation of foreign matter inside the polishing apparatus and the entry of foreign matter from the outside, it becomes possible to more effectively prevent the foreign matter from entering the polishing liquid. .

[Example]
Next, specific examples of the above embodiment will be described.

Example 1
In Example 1, both surfaces of the glass substrate after the second lapping process were polished using the polishing apparatus according to the first embodiment (polishing process). That is, the glass substrate was polished in a state where the polished portion was covered with the cover 90.

(Glass substrate)
The dimension of the glass substrate after the 2nd lapping process used for Example 1 is shown.
Size: Diameter (2R) = 65 [mm]
Glass substrate thickness = 0.65 [mm]
In Example 1, a borosilicate glass amorphous glass substrate was used.

(Polishing process)
The surface of the glass substrate after the second lapping step was polished. The polishing conditions are shown below.
Polishing machine: A 16B type double-side polishing machine manufactured by Speed Fam Co., Ltd. was used.
This polishing machine is provided with an acrylic plate enclosure structured to take outside air through a HEPA filter.
Polishing liquid: Showa Denko Rocks A-10 was adjusted to a concentration of 100 g / L. As the solvent, tap water filtered through a 0.1 μm filter was used.
Abrasive cloth: KM1700 suede type abrasive cloth manufactured by Fujibo.
Polishing conditions: Polishing pressure: 150 g / cm ² Surface plate rotation speed: 25 rpm, Polishing amount: 30 μm
Number of processed sheets: 100 sheets / time, processed 10 times, and counted the number of defects due to scratches.

(Evaluation)
A non-defective product and a defective product were selected with a laser scattering type visual inspection machine (Ver. 9) manufactured by System Seiko. Thereafter, the content classification of defective products was performed with a microscope, and the ratio of defective products due to polishing scratches was evaluated.
Appearance rate of visual inspection machines: average 95.8%, maximum 98%, minimum 94%
Content classification of defective products: Among 42 observation objects, there were no defects due to polishing scratches.

(Example 2)
In Example 2, the polishing apparatus according to the second embodiment was used to polish both surfaces of the glass substrate after the second lapping process (polishing process). That is, the glass substrate was polished by using a polishing apparatus in which the polishing liquid circulating unit 80 was made of resin. Since conditions such as the dimensions of the glass substrate used in Example 2 are the same as those in Example 1, description thereof is omitted.

(Configuration of polishing liquid circulation unit 80)
Teflon coating was applied to the tank 81 and a Teflon tube was used for the hose 82.

(Polishing process)
The surface of the glass substrate after the second lapping step was polished. Since the polishing conditions are the same as those in Example 1, description thereof is omitted.

(Evaluation)
Using the same apparatus as in Example 1, non-defective products and defective products were selected, and the ratio of defects due to polishing scratches was evaluated.
Appearance rate of appearance inspection machines: average 97%, maximum 99%, minimum 95%
Content classification of defective products: Out of 30 observation objects, there were no defects due to polishing scratches.

(Comparative example)
Next, a comparative example for the above embodiment will be described. In the comparative example, the glass substrate was polished by forming the polishing liquid circulating portion with metal (iron in this comparative example) without providing the cover 90 in the polishing portion. Also in the comparative example, both surfaces of the glass substrate after the second lapping step were polished. Since the conditions such as the dimensions of the glass substrate are the same as those in the first embodiment, the description thereof is omitted.

(Polishing process)
The surface of the glass substrate after the second lapping step was polished. Since the polishing conditions are the same as those in Example 1, description thereof is omitted.

(Evaluation)
Using the same apparatus as in Example 1, non-defective products and defective products were selected, and the ratio of defects due to polishing scratches was evaluated.
Appearance rate of appearance inspection machines: average 89%, maximum 95%, minimum 85%
Content classification of defective products: Out of 110 observation objects, 63 defects were caused by polishing scratches.

  As described above, according to Example 1 and Example 2, it is possible to reduce the number of defects (scratches) generated on the surface of the glass substrate as compared with the comparative example. That is, in Example 1, since the cover 90 was able to prevent foreign substances from entering the polishing liquid from the outside of the polishing apparatus, the number of defects (scratches) generated on the surface of the glass substrate could be reduced. . Moreover, in Example 2, since the generation | occurrence | production of the foreign material inside a polishing apparatus was able to be suppressed by comprising the polishing liquid circulation part 80 with resin, the number of the defects (scratches) which generate | occur | produce on the surface of a glass substrate. Could be reduced. Thus, according to the embodiment of the present invention, the appearance yield of the glass substrate after the completion of polishing could be greatly improved.

1 is a cross-sectional view of a polishing apparatus according to a first embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lower surface plate 20 Upper surface plate 30 Sun gear 40 Internal gear 50 Carrier 60 Polishing liquid supply part 70 Polishing liquid collection | recovery part 80 Polishing liquid circulation part 90 Cover W Workpiece to be polished

Claims (7)

An upper surface plate and a lower surface plate that sandwich and polish a workpiece to be polished from above and below;
A polishing liquid supply section for supplying a polishing liquid to the workpiece to be polished;
A polishing liquid recovery section for recovering the polishing liquid flowing downward from the lower surface plate;
A polishing liquid circulation section for returning the polishing liquid recovered by the polishing liquid recovery section to the polishing liquid supply section;
A cover that covers the polishing liquid supply unit and the polishing liquid recovery unit;
A polishing apparatus comprising:   The polishing apparatus according to claim 1, wherein the cover further covers the polishing liquid circulation unit.   The polishing according to claim 1, wherein an air filter is provided on the cover, and air is supplied from the outside to a space surrounded by the cover via the air filter. apparatus.   The polishing apparatus according to any one of claims 1 to 3, wherein a portion of the polishing liquid circulating unit that is in contact with the polishing liquid is made of a resin. An upper surface plate and a lower surface plate that sandwich and polish a workpiece to be polished from above and below;
A polishing liquid supply section for supplying a polishing liquid to the workpiece to be polished;
A polishing liquid recovery section for recovering the polishing liquid flowing downward from the lower surface plate;
A portion in contact with the polishing liquid is made of a resin, and a polishing liquid circulation unit that returns the polishing liquid recovered by the polishing liquid recovery unit to the polishing liquid supply unit,
A polishing apparatus comprising: The polishing liquid circulation unit includes a tank that collects and stores the polishing liquid from the polishing liquid recovery unit, and a pipe that supplies the polishing liquid stored in the tank to the polishing liquid supply unit.
The polishing apparatus according to claim 4, wherein an inner surface of the tank and an inner surface of the pipe are made of the resin.   6. The polishing apparatus according to claim 4, wherein the polishing liquid circulating unit has an area of 90% or more of a portion in contact with the polishing liquid made of a resin.

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