TW201600233A - Polishing pad and method for producing polishing pad - Google Patents

Abstract

The purpose of the present invention is to provide a polishing pad that is capable of achieving a good balance between processing efficiency and finish flatness at high levels. A polishing pad according to the present invention has a base and a polishing layer that is laminated on the front surface of the base. This polishing pad is characterized in that: the polishing layer comprises a binder that is mainly composed of a resin or an inorganic material and diamond abrasive grains that are dispersed in the binder; and the diamond abrasive grains have an average shape factor of from 1 to 1.33 (inclusive). It is preferable that a main component of the binder is a thermosetting resin or a photocurable resin. It is preferable that a main component of the binder is a silicate salt. It is preferable that the polishing layer has a plurality of projected portions in the front surface and the plurality of projected portions are regularly arranged. It is preferable that an adhesive layer is provided on the back surface of the base. It is preferable that the adhesive layer is configured of an adhesive. It is preferable that the base has flexibility or ductility.

Description

Method for manufacturing polishing pad and polishing pad

The present invention relates to a method of manufacturing a polishing pad and a polishing pad.

In recent years, progress has been made in the precision of electronic devices such as hard disks. In consideration of rigidity, impact resistance, and heat resistance which can be reduced in size and thickness, glass or the like can be used as the substrate material of such an electronic device.

The processing of such a substrate (the object to be polished) is mainly classified into a grinding process and a polishing process. First, physical polishing processing using hard particles such as diamond is performed in the polishing process to control or flatten the thickness of the substrate. Then, chemical polishing processing using fine particles such as ceria is performed in the polishing process to improve the flatness accuracy of the surface of the substrate.

In general, if the flattening accuracy of finishing is to be improved, the processing time tends to be long, and the processing efficiency and the flattening accuracy become a trade-off relationship. Therefore, it is difficult to achieve both processing efficiency and flattening accuracy. On the other hand, in order to achieve both the processing efficiency and the flattening precision in the polishing process, there has been proposed a polishing pad having an abrasive layer containing a binder and abrasive grains, and the polishing layer has a convex portion (refer to Japanese Patent Special) Table 2002-542057).

However, even if the polishing pad of the prior art is used, it is not sufficient to achieve both the processing efficiency and the flattening accuracy, and it is highly desirable to achieve a higher level of processing efficiency and finishing flatness. [Prior Art Document] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-542057

[Problems to be solved by the invention]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polishing pad which can attain a high level of processing efficiency and finishing flatness. [Means for solving the problem]

As a result of intensive studies, the inventors of the present invention have found that by using diamond abrasive grains having an average shape factor within a certain range, the processing efficiency of the object to be polished and the flatness of finishing can be achieved at a high level, thereby completing the present invention. invention.

That is, the invention completed to solve the above problems is a polishing pad having a substrate and an abrasive layer laminated on the surface side of the substrate, and the polishing pad is characterized in that the polishing layer has A binder containing a resin or an inorganic component as a main component, and diamond abrasive grains dispersed in the binder, wherein the diamond abrasive grains have an average shape factor of 1 or more and 1.33 or less.

Since the polishing pad has diamond abrasive grains having an average shape factor within the above range, the polishing pad can achieve both high processing efficiency and finishing flatness at a high level. Therefore, the polishing pad can planarize the surface of the object to be polished such as a glass substrate in a short time.

The main component of the binder may be a thermosetting resin or a photocurable resin. In this way, when the main component of the binder is a thermosetting resin or a photocurable resin, it is easy to ensure good dispersibility of the diamond abrasive grains and good adhesion to the substrate when the binder is formed, and it is easy to form a polishing. Floor. As a result, the durability of the polishing layer can be improved, and the processing efficiency at the time of polishing can be improved.

The main component of the binder may be a citrate. Thus, by setting the main component of the binder to a niobate, the abrasive particle holding power of the polishing layer can be improved.

The abrasive layer may have a plurality of convex portions on the surface, and the plurality of convex portions may be regularly arranged. Thus, the polishing layer has a plurality of convex portions on the surface, and the plurality of convex portions are regularly arranged, whereby the anisotropy of polishing is lowered, and the surface to be polished can be easily flattened.

There may be an adhesive layer on the back side of the substrate. Thus, by having an adhesive layer on the back side of the substrate, the polishing pad can be easily and reliably fixed to the support for mounting on the polishing apparatus.

The adhesive layer may be composed of an adhesive. By forming the adhesive layer with an adhesive as described above, the polishing pad can be peeled off and attached from the support, so that the polishing pad and the support can be easily reused.

The substrate can have flexibility or ductility. Thus, the substrate has flexibility or ductility, and the polishing pad follows the surface shape of the object to be polished, and the polishing surface is in easy contact with the object to be polished, so that the processing efficiency is further improved.

Another invention completed to solve the above problems is a method for producing a polishing pad for producing a polishing pad having a substrate and a polishing layer laminated on the surface side of the substrate, and the manufacturing method It is characterized in that the polishing layer is formed by printing of a composition for a polishing layer, and a polishing layer composition is used in the polishing layer forming step, and the polishing layer composition has a resin or an inorganic material as a main component. The binder component of the component and the diamond abrasive grain having an average shape factor of 1 or more and 1.33 or less.

In the method for producing a polishing pad, since the polishing layer is formed by printing the composition for the polishing layer, the production efficiency is good. Further, in the method for producing a polishing pad, since a polishing layer having diamond abrasive grains having an average shape factor of 1 or more and 1.33 or less is formed, it is possible to produce a polishing which can achieve both high processing efficiency and finishing flatness of the object to be polished. pad.

Here, the "average shape factor" is a case where the diameter of a circle cut out from the projection surface of the abrasive grain is D (μm) and the area of the projection surface of the abrasive grain is A (μm ² ). (D ² /A) The average of the amounts represented by ×(π/4). [Effects of the Invention]

As described above, according to the polishing pad of the present invention, both the processing efficiency and the finishing flatness can be achieved at a high level. Therefore, the polishing pad can planarize the surface of the object to be polished such as a glass substrate in a short time.

[First embodiment] Hereinafter, embodiments of the present invention will be described in detail with reference to the appropriate drawings.

<Polishing Pad> The polishing pad 1 shown in FIG. 1A and FIG. 1B includes a resin substrate 10, a polishing layer 20 laminated on the surface side of the substrate 10, and a bonding layer laminated on the back side of the substrate 10. Layer 30.

(Substrate) The substrate 10 is a plate-like member for supporting the polishing layer 20.

The material of the substrate 10 is not particularly limited, and examples thereof include polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and polyfluorene. Polyimide (PI), polyethylene naphthalate (PEN), aromatic polyamine, aluminum, copper, and the like. Among them, PET and PI which are excellent in adhesion to the polishing layer 20 are preferable. Further, the surface of the substrate 10 may be subjected to a treatment for improving adhesion such as chemical treatment, corona treatment, or primer treatment.

The substrate 10 can have flexibility or ductility. As described above, the substrate 10 has flexibility or ductility, and the polishing pad 1 follows the surface shape of the object to be polished, and the polishing surface is easily brought into contact with the object to be polished, and the processing efficiency is further improved. Examples of the material of the flexible substrate 10 include PET or PI. Moreover, as a material of the ductile base material 10, aluminum or copper is mentioned.

The shape and size of the substrate 10 are not particularly limited, and may be, for example, a square shape of 150 mm × 150 mm or an annular shape having an outer diameter of 637 mm and an inner diameter of 234 mm. Further, the plurality of substrates 10 juxtaposed on a plane may be configured to be supported by a single support.

The average thickness of the substrate 10 is not particularly limited, and may be, for example, 75 μm or more and 1 mm or less. When the average thickness of the substrate 10 is less than the lower limit, there is a concern that the strength or flatness of the polishing pad 1 is insufficient. On the other hand, when the average thickness of the substrate 10 exceeds the upper limit, there is a concern that the polishing pad 1 is unnecessarily thick and difficult to handle.

(Abrasion Layer) The polishing layer 20 has a binder 21 and diamond abrasive grains 22 dispersed in the binder 21. Further, the polishing layer 20 has a plurality of convex portions 23 on the surface.

The average thickness of the polishing layer 20 (only the average thickness of the portion of the convex portion 23) is not particularly limited, and the lower limit of the average thickness of the polishing layer 20 is preferably 100 μm, more preferably 130 μm. Further, the upper limit of the average thickness of the polishing layer 20 is preferably 1000 μm, more preferably 800 μm. When the average thickness of the polishing layer 20 is less than the lower limit, there is a concern that the durability of the polishing layer 20 is insufficient. On the other hand, when the average thickness of the polishing layer 20 exceeds the upper limit, there is a concern that the polishing pad 1 is unnecessarily thick and difficult to handle.

(Binder) The binder 21 contains a resin or an inorganic substance as a main component.

The resin is not particularly limited, and is preferably a thermosetting resin or a photocurable resin. Examples of the thermosetting resin include polyurethane, polyphenol, epoxy resin, polyester, cellulose, ethylene copolymer, polyvinyl acetal, polyacrylic acid, acrylate resin, polyvinyl alcohol, and poly Vinyl chloride, polyvinyl acetate, polyamine, and the like. Further, examples of the photocurable resin include an acrylate resin, an urethane acrylate resin, a vinyl ester resin, and a polyester-alkyd. Among them, a thermosetting epoxy resin is preferred. When the thermosetting epoxy resin constitutes the binder 21, it is easy to ensure good dispersibility of the diamond abrasive grains 22 and good adhesion to the substrate 10. Further, even if an ultraviolet curable resin to which an ultraviolet curable agent is added or a resin to which a curing agent is added to a thermoplastic resin such as polyacrylic acid is used, it is easy to ensure good dispersibility of the diamond abrasive grains 22 and good adhesion to the substrate 10. The adhesion. In addition, at least a portion of the resin of the binder 21 may be crosslinked.

Examples of the inorganic substance include decanoate, phosphate, and polyvalent metal alkoxide. Among them, a niobate having excellent polishing particle retention of the polishing layer 20 is preferable.

The binder 21 may suitably contain various additives such as a dispersing agent, a coupling agent, a surfactant, a lubricant, an antifoaming agent, and a coloring agent, and additives, etc., depending on the purpose.

(Abrasive Grain) The lower limit of the average particle diameter of the diamond abrasive grains 22 is preferably 1 μm, more preferably 3 μm. Further, the upper limit of the average particle diameter of the diamond abrasive grains 22 is preferably 20 μm, more preferably 15 μm. When the average particle diameter of the diamond abrasive grains 22 is less than the lower limit, there is a fear that the polishing rate is insufficient. On the other hand, when the average particle diameter of the diamond abrasive grains 22 exceeds the upper limit, there is a concern that the object to be polished is damaged.

The lower limit of the average shape factor of the diamond abrasive grains 22 is 1. Further, the upper limit of the average shape factor of the diamond abrasive grains 22 is 1.33, and more preferably 1.3. When the average shape factor of the diamond abrasive grains 22 exceeds the upper limit, there is a concern that it is difficult to achieve both high processing efficiency and finishing flatness of the object to be polished. In addition, the average shape factor of the diamond abrasive grains 22 is not less than one according to its definition.

The lower limit of the content of the diamond abrasive grains 22 with respect to the polishing layer 20 is preferably 35% by mass, and more preferably 40% by mass. Further, the upper limit of the content of the diamond abrasive grains 22 with respect to the polishing layer 20 is preferably 70% by mass, and more preferably 65% by mass. When the content of the diamond abrasive grains 22 with respect to the polishing layer 20 is less than the lower limit, there is a concern that the polishing force of the polishing layer 20 is insufficient. On the other hand, when the content of the diamond abrasive grains 22 with respect to the polishing layer 20 exceeds the upper limit, there is a concern that the object to be polished is damaged.

(Protruding Portion) The polishing layer 20 has a plurality of convex portions 23 arranged in a lattice shape at equal intervals on the surface. The shape of the plurality of convex portions 23 is a regular square pattern. The bottom surface of the portion (groove portion) other than the convex portion 23 of the polishing layer 20 is composed of the surface of the substrate 10.

The lower limit of the average area of the convex portion 23 is preferably 0.5 mm ² , more preferably 1 mm ² . Further, the upper limit of the average area of the convex portion 23 is preferably 3 mm ² , more preferably 2.5 mm ² . When the average area of the convex portion 23 is smaller than the lower limit, there is a concern that the convex portion 23 of the polishing layer 20 is peeled off. On the other hand, when the average area of the convex portion 23 exceeds the upper limit, the frictional resistance of the polishing layer 20 during polishing may increase, and the object to be polished may be damaged.

The lower limit of the area occupation ratio of the plurality of convex portions 23 with respect to the entire polishing layer 20 is preferably 15%, more preferably 20%. Further, the upper limit of the area occupancy ratio of the plurality of convex portions 23 with respect to the entire polishing layer 20 is preferably 40%, more preferably 35%. When the area occupation ratio of the plurality of convex portions 23 with respect to the entire polishing layer 20 is less than the lower limit, the convex portion 23 of the polishing layer 20 may be peeled off. On the other hand, when the area occupation ratio of the plurality of convex portions 23 with respect to the entire polishing layer 20 exceeds the upper limit, the frictional resistance of the polishing layer 20 during polishing becomes high, and the object to be polished is damaged. Worry. Further, the "area of the entire polishing layer" is a concept including the area of the void of the polishing layer.

(Adhesive Layer) The adhesive layer 30 is a layer that fixes the polishing pad 1 on a support for supporting the polishing pad 1 and attached to the polishing apparatus.

The adhesive used for the adhesive layer 30 is not particularly limited, and examples thereof include a reactive adhesive, an instant adhesive, a hot melt adhesive, and an adhesive.

As the adhesive used for the adhesive layer 30, an adhesive is preferred. By using an adhesive as the adhesive for the adhesive layer 30, the polishing pad 1 can be peeled off from the support and replaced, so that the polishing pad 1 and the support can be easily reused. The adhesive is not particularly limited, and examples thereof include an acrylic adhesive, an acrylic-rubber adhesive, a natural rubber adhesive, a synthetic rubber adhesive such as a butyl rubber, and an anthrone-based adhesive. A polyurethane adhesive, an epoxy adhesive, a polyethylene adhesive, a polyester adhesive, or the like.

The lower limit of the average thickness of the adhesive layer 30 is preferably 0.05 mm, more preferably 0.1 mm. Further, the lower limit of the average thickness of the adhesive layer 30 is preferably 0.3 mm, more preferably 0.2 mm. When the average thickness of the adhesive layer 30 is less than the lower limit, there is a concern that the adhesion is insufficient and the polishing pad 1 is peeled off from the support. On the other hand, when the average thickness of the adhesive layer 30 exceeds the upper limit, for example, there is a concern that workability is lowered when the polishing pad 1 is cut into a desired shape due to the thickness of the adhesive layer 30. .

(Manufacturing Method of Polishing Pad) The polishing pad 1 can be produced by the steps of preparing a composition for a polishing layer and forming the polishing layer 20 by printing of a composition for a polishing layer.

First, in the polishing layer composition preparation step, a solution obtained by dispersing a polishing layer composition (formation material of the binder 21 and diamond abrasive grains 22) in a solvent is prepared as a coating liquid. The solvent is not particularly limited as long as it is soluble in the material for forming the binder 21 . Specifically, methyl ethyl ketone (Methyl Ethyl Ketone, MEK), isophorone, rosinol, N-methylpyrrolidone, cyclohexanone, propylene carbonate or the like can be used. In order to control the viscosity or fluidity of the coating liquid, a diluent such as water, an alcohol, a ketone, an acetate or an aromatic compound may be added.

Then, in the polishing layer forming step, the coating liquid prepared in the composition layer preparation step of the polishing layer is applied onto the surface of the substrate 10, and the polishing layer 20 having the convex portion 23 is formed by a printing method. In order to form the convex portion 23, a mask having a shape corresponding to the shape of the convex portion 23 is used. The coating liquid is applied (printed) using the mask. As the coating method, for example, bar coating, reverse roll coating, blade coating, screen printing, gravure coating, die coating, or the like can be used. Further, the polishing layer 20 is formed by drying and reacting the applied coating liquid. Specifically, for example, the solvent of the coating liquid is evaporated by heat of 100 ° C or more and 120 ° C or less, and then the solvent of the coating liquid is cured by heat of 80 ° C or more and 120 ° C or less to form the binder 21 .

(Advantages) In the polishing pad 1, since the polishing layer 20 has the diamond abrasive grains 22 having an average shape factor of 1 or more and 1.33 or less, the processing efficiency and finishing flatness of the object to be polished can be achieved at a high level. Therefore, the polishing pad 1 can planarize the surface of the object to be polished such as a glass substrate in a short time. In addition, the polishing pad 1 has a plurality of convex portions 23 on the surface by the polishing layer 20, and the shapes of the plurality of convex portions 23 are regularly arranged in a square pattern shape, and the anisotropy of the polishing Lowering can further flatten the surface to be polished. Further, the polishing pad 1 can easily and reliably fix the polishing pad 1 to a support for mounting on a polishing apparatus by providing the adhesive layer 30 on the back side of the substrate 10. Further, in the method of manufacturing the polishing pad 1, since the polishing layer 20 is formed by printing of the composition for the polishing layer, the manufacturing efficiency is good.

[Other Embodiments] The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made in addition to the above-described embodiments. In the above-described embodiment, the convex portions are formed in a lattice shape at equal intervals, but the intervals of the lattices may not be equal intervals, and for example, the vertical direction and the lateral direction may be changed. However, when the intervals of the convex portions are different, there is a concern that the polishing generates anisotropy, and therefore it is preferably at equal intervals. Further, the planar shape of the convex portion may not be a lattice shape, and may be, for example, a polygonal shape other than the repeated quadrilateral, a circular shape, a shape having a plurality of parallel lines, or the like.

Further, in the above embodiment, the bottom surface of the plurality of groove portions is a surface of the base material, but the depth of the groove portion is smaller than the average thickness of the polishing layer, and the groove portion may not reach the surface of the base material. At this time, the depth of the groove portion may be set to 50% or more of the average thickness of the polishing layer. When the depth of the groove portion is less than the lower limit, there is a fear that the groove portion is lost due to abrasion, and the durability of the polishing pad may be poor.

In the above-described embodiment, a method of forming a convex portion is disclosed. However, after the composition for the polishing layer is printed on the entire surface of the substrate, it can be formed by etching or laser processing. Convex.

Further, in the above-described embodiment, the polishing layer has a configuration having a convex portion, but the convex portion is not an essential component. For example, a polishing layer can be laminated on the surface of the substrate.

Further, as shown in FIG. 2, the polishing pad 2 may include a support 40 laminated via the adhesive layer 30 on the back side, and a second adhesive layer 31 laminated on the back side of the support 40. . Since the polishing pad 2 is provided with the support 40, the operation of the polishing pad 2 becomes easy.

Examples of the material of the support 40 include thermoplastic resins such as polypropylene, polyethylene, polytetrafluoroethylene, and polyvinyl chloride, or polycarbonate, polyamide, polyethylene terephthalate, and the like. Engineering plastics. The support 40 is made of such a material, and the support 40 has flexibility. The polishing pad 2 follows the surface shape of the object to be polished, and the polished surface is in easy contact with the object to be polished. Therefore, the processing efficiency is further improved. improve.

The average thickness of the support 40 can be, for example, 0.5 mm or more and 2 mm or less. When the average thickness of the support 40 is less than the lower limit, there is a concern that the strength of the polishing pad 2 is insufficient. On the other hand, when the average thickness of the support body 40 exceeds the upper limit, there is a concern that it is difficult to attach the support body 40 to the polishing apparatus or the flexibility of the support body 40 is insufficient. [Examples]

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples, but the invention is not limited to the following examples.

[Example 1] Diamond abrasive grains ("LS series" of Lands Corporation) were prepared, and the average particle diameter and average shape were measured using Malvern's "Morphologi G3". coefficient. The results are shown in Table 1.

Adding a diluent solvent (isophorone) and a hardener ("YH306" from Mitsubishi Chemical Corporation, and "Library of Shikoku Chemical Industry Co., Ltd." to epoxy resin ("JER828" of Mitsubishi Chemical Corporation) The diamond abrasive grains of Curezol 1B2MZ" and the above-mentioned diamond abrasive grains were mixed so that the content of the diamond abrasive grains was 55% by mass with respect to the polishing layer, and a coating liquid was obtained.

As the substrate, a PET film having an average thickness of 75 μm ("Melinex S" of Teijin Dupont Films Co., Ltd.) was used, and was formed on the surface of the substrate by printing. An abrasive layer of the convex portion. Further, a convex portion is formed in the polishing layer by using a mask corresponding to the convex portion as a printed pattern. The convex portion was formed into a square shape having a side of 1.5 mm in plan view, and the average thickness was set to 135 μm. The convex portions were formed in a regular square pattern, and the area ratio of the convex portions to the entire polishing layer was 36%.

Further, as a support for supporting the polishing pad and fixed to the polishing apparatus, a hard vinyl chloride resin sheet ("SP770" of Takiron Co., Ltd.) having an average thickness of 1 mm was used, with an average thickness of 130 μm. The adhesive material bonds the back surface of the substrate to the surface of the support. As the adhesive material, a double-sided tape ("5605HGD" of Sekisui Chemical Co., Ltd.) was used.

[Example 2, Example 3, Comparative Example 1 to Comparative Example 3] The average particle diameter and the average shape factor of the diamond abrasive grains of Example 1 were changed as shown in Table 1, and Example 2, Example 3, and Comparative Example were obtained. 1 to Comparative Example 3.

[Example 4] The same diamond abrasive grains as in Example 1 were used, and ceric acid salt ("SAL" brand of Fuji Chemical Co., Ltd.) and a hardener (Fuji Chemical Co., Ltd.) and a hardener were mixed in the diamond abrasive grains. "Rikaset No. 5" of Kobe Chemical Industry Co., Ltd. is adjusted so that the content of the diamond abrasive grains is 65 mass%, the content of the citrate is 34 mass%, and the content of the hardener is 1 mass%. And obtain a molding liquid.

The molding liquid was poured into a polytetrafluoroethylene resin mold having a depth of 1 mm in a square shape having a side of 3 mm, and dehydrated at 90 ° C for 1 hr or more, and then released from the resin mold at 300 ° C. The calcination was carried out for 1 hr to prepare a convex portion.

As the substrate, an aluminum plate having an average thickness of 500 μm was used, and the convex portions obtained by the calcination were arranged in a square pattern at a pitch of 5 mm on the surface of the substrate by an inorganic binder (East Asia Synthetic Co., Ltd.'s "ARON CERAMIC D" is bonded. The area ratio of the convex portion to the entire polishing layer was 36%. Then, the surface of the convex portion was flattened using WA#800 grinding stone.

In addition, as a support for supporting the polishing pad and fixed to the polishing apparatus, a hard vinyl chloride resin sheet ("SP770" of Takiron Co., Ltd.) having an average thickness of 1 mm was used, and an adhesive material having an average thickness of 130 μm was used. The back surface of the substrate is bonded to the surface of the support. As the adhesive material, a double-sided tape ("5605HGD" of Sekisui Chemical Co., Ltd.) was used.

[Example 5, Comparative Example 4] The average particle diameter and the average shape factor of the diamond abrasive grains of Example 4 were changed as in Table 1, and Example 5 and Comparative Example 4 were obtained.

[Polishing Conditions] Using the polishing pads obtained in the above-described Examples 1 to 5 and Comparative Examples 1 to 4, the glass substrate was polished. As the glass substrate, three pieces of soda lime glass (manufactured by Hiraoka Special Glass Co., Ltd.) having a diameter of 6.25 cm and a specific gravity of 2.4 were used. A commercially available double side grinder (ENGIS JAPAN Co., Ltd. "EJD-5B-3W") was used for the polishing. The carrier of the double side grinder is an epoxy glass having a thickness of 0.6 mm. The grinding was carried out by setting the grinding pressure to 200 g/cm ² for 15 minutes at an upper platen rotation speed of 60 rpm, a lower platen rotation speed of 90 rpm, and a sun (SUN) gear rotation speed of 30 rpm. At this time, as a coolant, MORESCO Co., Ltd.'s "Toolmate GR-20" was supplied at 120 cc per minute.

[Evaluation Method] Using the polishing pads of Examples 1 to 5 and Comparative Examples 1 to 4, the polishing rate and the surface roughness (Ra) of the object to be polished after polishing were determined as the polished glass substrate. The evaluation of both the processing efficiency and the finishing flatness was carried out, and the value obtained by dividing the polishing rate by the surface roughness (Ra) (consistent level) was evaluated. The above-mentioned level is a large numerical value when the polishing rate is high, the processing efficiency is high, the surface roughness is low, and the finishing flatness is high, and the degree of compatibility between the processing efficiency and the finishing flatness is indicated. The results are shown in Table 1. Further, the polishing rate and the surface roughness (Ra) were determined by the methods shown below.

(Polishing Rate) Regarding the polishing rate, the weight change (g) of the glass substrate before and after the polishing was divided by the surface area (cm ² ) of the glass substrate, the specific gravity (g/cm ³ ) of the glass substrate, and the polishing time (minutes).

(Surface roughness) For the surface roughness, a contact surface roughness meter ("S-3000" from Mitutoyo Co., Ltd.) was used, and four arbitrary portions on the front and back sides were measured to obtain a total of eight. The average of the parts.

According to Table 1, the level of the polishing rate divided by Ra does not depend on the average particle diameter of the abrasive grains or the amount of abrasive grains of the diamond abrasive grains, and is high in Examples 1 to 5 having an average shape factor of 1.33 or less. It was low in Comparative Example 1 to Comparative Example 4 in which the average shape factor exceeded 1.33. Therefore, it is understood that the processing efficiency and the finishing flatness can be achieved at a high level by setting the average shape factor of the diamond abrasive grains to 1.33 or less. [Industrial availability]

According to the polishing pad of the present invention, both the processing efficiency and the finishing flatness can be achieved at a high level. Therefore, the polishing pad can planarize the surface of the object to be polished such as a glass substrate in a short time.

1, 2‧‧‧ polishing pad
10‧‧‧Substrate
20‧‧‧Abrasive layer
21‧‧‧Binder
22‧‧‧Diamond abrasive grains
23‧‧‧ convex
30‧‧‧ adhesive layer
31‧‧‧Second adhesive layer
40‧‧‧Support

Fig. 1A is a schematic plan view showing a polishing pad according to an embodiment of the present invention. Fig. 1B is a schematic end view of the line A-A of Fig. 1A. Fig. 2 is a schematic end view showing a polishing pad of a different embodiment from Fig. 1B.

1‧‧‧ polishing pad

10‧‧‧Substrate

20‧‧‧Abrasive layer

21‧‧‧Binder

22‧‧‧Diamond abrasive grains

23‧‧‧ convex

30‧‧‧ adhesive layer

Claims (8)

A polishing pad having a substrate and an abrasive layer laminated on a surface side of the substrate, wherein the polishing pad has a binder containing a resin or an inorganic component as a main component, and is dispersed In the diamond abrasive grains in the binder, the diamond abrasive grains have an average shape factor of 1 or more and 1.33 or less. The polishing pad according to claim 1, wherein the main component of the adhesive is a thermosetting resin or a photocurable resin. The polishing pad according to claim 1, wherein the main component of the binder is citrate. The polishing pad according to claim 1, wherein the polishing layer has a plurality of convex portions on a surface, and the plurality of convex portions are regularly arranged. The polishing pad according to claim 1, wherein the substrate has an adhesive layer on the back side of the substrate. The polishing pad of claim 5, wherein the adhesive layer is composed of an adhesive. The polishing pad of claim 1, wherein the substrate has flexibility or ductility. A method for producing a polishing pad for producing a polishing pad having a substrate and an abrasive layer laminated on a surface side of the substrate, and the manufacturing method is characterized by comprising printing by a composition for a polishing layer In the step of forming the polishing layer, in the polishing layer forming step, a composition for a polishing layer having a binder component containing a resin or an inorganic component as a main component and an average shape factor is used. Diamond abrasive grains of 1 or more and 1.33 or less.