JP3224896U - Polishing pad - Google Patents

Abstract

An object of the present invention is to provide a polishing pad having an excellent polishing rate particularly under the condition that the number of revolutions of a platen of a polishing machine and the polishing pressure are increased. The polishing island includes a substrate and a polishing island laminated on one surface of the substrate and containing abrasive grains and a binder, and the central axis of the polishing island is orthogonal to the one surface. A plurality of columnar polishing portions 21 are provided, and the area of the top surface of the polishing portion is 10 mm2 or more and 27.5 mm2 or less. [Selection diagram] FIG.

Description

  The present invention relates to a polishing pad.

  For example, a smartphone has its screen surface covered with a cover glass. Such a cover glass is completed by polishing a glass substrate, which is a raw material, to a predetermined thickness while flattening the surface, and then chamfering, drilling, chemical strengthening, printing, and the like. Among these, for polishing, a fixed abrasive grain type polishing pad having a base material and a polishing layer (polishing island) laminated on one surface of the base material and containing abrasive grains and a binder can be used.

  By the way, with the recent increase in the size of the smartphone screen, the size of the cover glass has also increased. With the increase in size, uniformity of the cover glass over a wide area is required, and high mechanical and optical quality is required for the sheet glass as a raw material. For this reason, the thickness of the plate glass used as a raw material has been increasing. On the other hand, the thickness of the cover glass itself is increasing with an increase in size, but the extent is low, and as a result, the amount of the plate glass as a raw material to be polished increases.

  If the amount to be polished increases, the processing time will increase as it is, and the production efficiency of the product will decrease. For this reason, there has been proposed a polishing pad which is excellent in polishing rate and hardly decreases in polishing rate for a relatively long period of time (for example, refer to JP-A-2017 / 163565). In the polishing pad described in this publication, an excellent polishing rate is achieved by using a plurality of types of abrasive grains having different average particle diameters, and a reduction in the polishing rate over a long period is suppressed.

JP-A-2017 / 163565

  However, in the above-mentioned conventional polishing pad, the polishing rate cannot be said to be sufficiently improved as compared with the increase in the amount to be polished, and a further improvement in the polishing rate is required. In order to further improve the polishing rate, it is effective to increase the number of revolutions of the platen of the polishing machine or increase the polishing pressure applied to the glass substrate via the polishing island.

  The present invention has been made in view of such inconvenience, and it is an object of the present invention to provide a polishing pad excellent in a polishing rate particularly under a condition in which the rotation speed and polishing pressure of a polishing machine are increased.

  The present inventors have conducted intensive studies on the polishing rate under the conditions of increasing the number of revolutions and polishing pressure of the platen of the polishing machine, and as a result, the configuration of a plurality of polishing sections constituting the polishing island has been greatly improved to improve the polishing rate. We found that we could be connected and completed the present invention.

That is, the polishing pad of the present invention has a substrate and a polishing island laminated on one surface of the substrate and containing abrasive grains and a binder, and the polishing island has a central axis thereof corresponding to the one surface. has a plurality of cylindrical abrasive section orthogonal, the area of the top surface of the polishing portion is 10 mm ² or more 27.5 mm ² or less.

  Since the polishing portion of the polishing pad has a cylindrical shape, chipping and cracking hardly occur in the polishing portion even when the polishing pressure is increased, and the polishing can be stably performed. In addition, the polishing pad, by setting the area of the top surface of the polishing portion within the above range, while being able to effectively receive the polishing pressure in the polishing portion while ensuring adhesion to the substrate, polishing Rate can be raised.

  The area occupation ratio of the plurality of polishing parts to the entire polishing island is preferably 40% or more and 65% or less. By setting the area occupation ratio of the plurality of polishing parts to the entire polishing island in the above range, an appropriate contact area to the workpiece and the polishing pressure can be secured, so that the polishing rate can be further increased. it can.

  The plurality of polishing units may be staggered. By arranging the plurality of polishing portions in a staggered manner as described above, the occurrence of the warpage of the base material can be suppressed, so that the in-plane uniformity of the polishing pressure can be improved and the polishing can be performed more stably.

  The minimum distance between the polishing parts is preferably 0.3 mm or more and 2.5 mm or less. By setting the minimum distance between the polishing portions within the above range, an appropriate contact area with the workpiece and the polishing pressure can be secured, so that the polishing rate can be further increased.

  The average thickness of the polishing island is preferably 0.5 mm or more and 2 mm or less. By setting the above to be within the above range, it is possible to extend the life of the polishing pad while suppressing the aspect ratio of the polishing portion from becoming large and the polishing portion from easily falling during grinding.

  Here, a “polishing island” having a plurality of polishing parts is defined as a polishing part whose distance to the nearest polishing part is approximately equal to D, for example, 2 × D or less, where D is the minimum distance between the polishing parts. Refers to a set of The “area of the entire polishing island” refers to the area including the groove when the groove exists between the polishing portions. The “average thickness” refers to the average value of the thickness measured at any 10 points.

  "A plurality of polishing sections are staggered" means that the polishing sections are arranged at equal intervals in a plurality of parallel rows, pass through the center of the polishing section included in one row, and with respect to this one row. An arrangement in which the centers of the polishing sections in the row adjacent to the one row are not positioned in the direction perpendicular to the row.

  As described above, the polishing pad of the present invention has an excellent polishing rate particularly under the condition that the rotation speed of the platen of the polishing machine and the polishing pressure are large.

FIG. 1 is a schematic plan view showing a polishing pad according to an embodiment of the present invention. FIG. 2 is a schematic partial enlarged plan view of the polishing pad of FIG. FIG. 3 is a schematic partial enlarged plan view of FIG. 2 further enlarged. FIG. 4 is a schematic partial sectional view taken along line AA of FIG. FIG. 5 is a schematic partial cross-sectional view showing a polishing pad according to an embodiment different from FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

  The polishing pad 1 shown in FIGS. 1 to 3 includes a substrate 10, a polishing island 20 laminated on one surface of the substrate 10 (hereinafter, also simply referred to as “front surface”), and the other of the substrate 10. And an adhesive layer 30 laminated on a surface (hereinafter, also simply referred to as a “back surface”). The polishing island 20 has a plurality of columnar polishing portions 21 whose central axes are orthogonal to the one surface, and grooves 22 disposed between the polishing portions 21.

  The polishing pad 1 is suitably used under conditions where the number of revolutions and polishing pressure of the platen of the polishing machine are large, especially under the condition that the number of revolutions is 50 or more and 2000 or less, preferably 150 or more and 1200 or less. be able to.

<Substrate>
The base material 10 is a plate-shaped or sheet-shaped member for supporting the polishing island 20.

  The main components of the base material 10 are not particularly limited, but include polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI), polyethylene naphthalate (PEN), aramid, and aluminum. , Copper and the like. Among them, PC having high heat resistance is preferable. Further, the surface of the base material 10 may be subjected to a treatment for enhancing adhesiveness, such as a chemical treatment, a corona treatment, and a primer treatment. Here, the "main component" means a component having the largest content, preferably a component having a content of 50% by mass or more, more preferably 90% by mass or more.

  Further, the base material 10 may have flexibility or ductility. Since the base material 10 has flexibility or ductility as described above, the polishing pad 1 follows the surface shape of the work, and the contact area between the polishing surface and the work is increased. Even higher. Examples of the material of such a flexible substrate 10 include PET and PI. In addition, examples of the material of the base material 10 having ductility include aluminum and copper.

  As a minimum of average thickness of substrate 10, 75 micrometers is preferred, 100 micrometers is more preferred, and 150 micrometers is still more preferred. On the other hand, the upper limit of the average thickness of the substrate 10 is preferably 3 mm, more preferably 1 mm, and even more preferably 500 μm. If the average thickness of the base material 10 is less than the lower limit, the strength and flatness of the polishing pad 1 may be insufficient. Conversely, if the average thickness of the base material 10 exceeds the upper limit, the polishing pad 1 becomes unnecessarily thick, and handling may be difficult.

  The shape and size of the base material 10 are appropriately determined according to the shape and size of the surface plate of the polishing machine used. For example, the base material 10 of the polishing pad 1 shown in FIG. 1 is annular. The annular base material 10 can have, for example, an outer diameter of 200 mm or more and 2022 mm or less and an inner diameter of 100 mm or more and 658 mm or less. The shape of the substrate 10 is not limited to an annular shape, and may be a circular shape having a diameter of 200 mm or more and 2022 mm or less, or a square shape having one side of 140 mm or more and 160 mm or less.

  In addition, from the viewpoint of handleability of the polishing pad 1, a configuration in which a plurality of base materials 10 are supported on a surface plate of a polishing machine can be adopted. In the polishing pad 1 shown in FIG. 1, the substrate 10 has a slit 10a on its surface, and the annular substrate 10 is divided into three by a straight line passing through the center by the slit 10a. The polishing island 20 is not formed on the slit 10a, and the polishing pad 1 can be easily cut along the slit 10a. As described above, in the polishing pad 1, the base material 10 is divided into three parts, transferred, and fixed to the platen of the polishing machine, thereby forming the annular polishing pad 1 shown in FIG. 1. .

  As a minimum of average width of slit 10a, 0.1 mm is preferred, 1 mm is more preferred, and 3 mm is still more preferred. On the other hand, the upper limit of the average width of the slit 10a is preferably 4 mm, more preferably 3.5 mm. If the average width of the slits 10a is less than the above lower limit, the polishing islands 20 adjacent to the slits 10a may be cut together at the time of division, and the polishing islands 20 may be easily damaged. Conversely, if the average width of the slits 10a exceeds the upper limit, the area of the polishing island 20 is relatively reduced, and the polishing rate may be reduced.

  Note that the number of divisions is not limited to three, but may be another division number such as four divisions or eight divisions. In addition, it is not essential to divide the base material 10 when the polishing pad 1 is transferred, and it is possible to transfer the polishing pad 1 without splitting.

<Polishing island>
As shown in FIG. 1, the polishing island 20 includes a plurality of regions (in FIG. 1, three polishing islands 20a, a second polishing island 20b, and a third polishing island 20c in FIG. 1) excluding the slits 10a. Area). The first polishing island 20a, the second polishing island 20b, and the third polishing island 20c have substantially the same shape. By making each region of the polishing island 20 substantially the same, the in-plane uniformity of the polishing pressure applied to each region is improved, and the polishing can be performed more stably.

  The polishing island 20 includes a plurality of abrasive grains 23 and a binder 24 in the polishing section 21.

(Abrasive)
Examples of the abrasive grains 23 include diamond abrasive grains, alumina abrasive grains, silica abrasive grains, ceria abrasive grains, and silicon carbide abrasive grains. Among them, diamond abrasive grains that are harder than other abrasive grains are preferable. By using the abrasive grains 23 as diamond abrasive grains, the polishing power is improved, and the polishing rate can be further improved.

  The diamond of the diamond abrasive grains may be a single crystal or polycrystal, or may be a diamond that has been subjected to a treatment such as Ni coating. Among them, single crystal diamond and polycrystalline diamond are preferable. Single crystal diamond is harder and has higher grinding power than other diamonds. In addition, polycrystalline diamond is easily cleaved in units of microcrystals constituting the polycrystal and is hardly blinded, so that even if polishing is performed for a long period of time, a reduction in polishing rate is small.

  The average particle diameter of the abrasive grains 23 is appropriately selected from the viewpoint of the polishing rate and the surface roughness of the workpiece after polishing. The lower limit of the average particle diameter of the abrasive grains 23 is preferably 2 μm, more preferably 10 μm, and still more preferably 20 μm. On the other hand, the upper limit of the average particle diameter of the abrasive grains 23 is preferably 200 μm, more preferably 100 μm, and still more preferably 50 μm. If the average particle diameter of the abrasive grains 23 is less than the above lower limit, the polishing power of the polishing pad 1 may be insufficient, and the polishing rate may be reduced. Conversely, if the average particle diameter of the abrasive grains 23 exceeds the above upper limit, polishing accuracy may be reduced. Here, the “average particle size” refers to a 50% value (50% particle size, D50) of a volume-based cumulative particle size distribution curve measured by a laser diffraction method or the like.

  The lower limit of the content of the abrasive grains 23 in the polishing section 21 is preferably 3% by volume, more preferably 4% by volume, and still more preferably 8% by volume. On the other hand, the upper limit of the content of the abrasive grains 23 is preferably 55% by volume, more preferably 45% by volume, and still more preferably 35% by volume. When the content of the abrasive grains 23 is less than the above lower limit, the polishing power of the polishing section 21 may be insufficient. Conversely, if the content of the abrasive grains 23 exceeds the upper limit, the polishing unit 21 may not be able to hold the abrasive grains 23.

(binder)
The main component of the binder 24 of the polishing section 21 is not particularly limited, but includes a resin or an inorganic substance.

  Examples of the resin include resins such as polyurethane, polyphenol, epoxy, polyester, cellulose, ethylene copolymer, polyvinyl acetal, polyacryl, acrylic ester, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, and polyamide. Among them, polyacryl, epoxy, polyester, and polyurethane, which easily ensure good adhesion to the substrate 10, are preferable. The resin may be at least partially crosslinked.

  Examples of the inorganic substance include silicates, phosphates, and polyvalent metal alkoxides. Among them, a silicate having a high abrasive grain holding power is preferable. Examples of such a silicate include sodium silicate and potassium silicate.

  The main component of the binder 24 is preferably an inorganic substance. By making the main component of the binder 24 inorganic, the holding power of the abrasive grains 23 is increased, and it is possible to prevent the abrasive grains 23 from dropping before they are spilled. For this reason, the grinding force is further increased.

  The binder 24 may appropriately contain various assistants and additives such as a dispersant, a coupling agent, a surfactant, a lubricant, an antifoaming agent, and a coloring agent according to the purpose.

(Other)
Further, the polishing section 21 may include other particles. Such other particles include fillers. By including the filler in the polishing section 21 as described above, the elastic modulus of the binder 24 is improved, and the polishing rate can be increased.

  Examples of the filler include, in addition to diamond, oxides such as alumina, silica, cerium oxide, magnesium oxide, zirconia, and titanium oxide, and composite oxides such as silica-alumina, silica-zirconia, and silica-magnesia. it can. These may be used alone or in combination of two or more as necessary. Among them, alumina which can obtain a high polishing force and is relatively inexpensive is preferable.

  Although the average particle diameter of the filler also depends on the average particle diameter of the abrasive grains 23, the lower limit of the average particle diameter of the filler is preferably 0.01 μm, more preferably 2 μm. On the other hand, the upper limit of the average particle size of the filler is preferably 20 μm, more preferably 15 μm. If the average particle diameter of the filler is less than the lower limit, the polishing rate may not be improved due to the insufficient effect of the filler on improving the elastic modulus of the binder 24. On the other hand, when the average particle size of the filler exceeds the upper limit, the filler may hinder the polishing power of the abrasive grains 23.

  The average particle diameter of the filler is preferably smaller than the average particle diameter of the abrasive grains 23. The lower limit of the ratio of the average particle diameter of the filler to the average particle diameter of the abrasive grains 23 is preferably 0.1, and more preferably 0.2. On the other hand, the upper limit of the ratio of the average particle diameter of the filler to the average particle diameter of the abrasive grains 23 is preferably 0.8, and more preferably 0.6. If the ratio of the average particle diameter of the filler to the average particle diameter of the abrasive grains 23 is less than the lower limit, the polishing rate may not be improved due to the insufficient effect of the filler on improving the elastic modulus of the binder 24. Conversely, if the ratio of the average particle diameter of the filler to the average particle diameter of the abrasive grains 23 exceeds the upper limit, the filler may hinder the polishing power of the abrasive grains 23.

  Although the content of the filler in the polishing portion 21 depends on the content of the abrasive grains 23, the lower limit of the content of the filler is preferably 15% by volume, more preferably 30% by volume. On the other hand, the upper limit of the content of the filler is preferably 75% by volume, more preferably 72% by volume. If the content of the filler is less than the lower limit, the polishing rate may be reduced due to the insufficient effect of the filler on improving the elastic modulus of the binder 24. Conversely, if the content of the filler exceeds the upper limit, the filler may hinder the polishing power of the abrasive grains 23.

(Polishing unit)
The plurality of polishing portions 21 included in the polishing island 20 are staggered as shown in FIGS. 2 and 3. By arranging the plurality of polishing units 21 in a staggered manner, the occurrence of the warpage of the base material 10 can be suppressed, so that the in-plane uniformity of the polishing pressure is improved, and the polishing can be performed more stably.

  The plurality of polishing units 21 are arranged in a plurality of parallel rows (in FIGS. 2 and 3, in the horizontal direction). The intervals (center-to-center distance, pitch) between the polishing units 21 arranged in one row are equal. The interval between the polishing sections 21 is the same between a plurality of rows. The centers of the polishing units 21 in the row adjacent to the one row are located in a direction perpendicular to the one row from the midpoint of a straight line connecting the centers of the polishing units 21 adjacent in the one row. That is, the position of the polishing unit 21 in the adjacent row is shifted by a half pitch from the position of the polishing unit 21 in one row. Therefore, as for the arrangement of the plurality of polishing sections 21, the same pattern is repeated every two rows in the plurality of rows. By arranging the plurality of polishing units 21 in this manner, the warpage of the base material 10 can be effectively reduced.

  In addition, three polishing units 21 adjacent to each other in one row and one polishing unit 21 located in a direction orthogonal to the one row from a midpoint of a straight line connecting the centers of the polishing units 21 are provided. It is preferable that a triangle (for example, a triangle indicated by a two-dot chain line in FIG. 3) having the center M of the polishing unit 21 as a vertex is a raw regular triangle. By making the triangle a regular triangle in this way, the isotropy in the column direction and the direction perpendicular to the column is enhanced, so that polishing can be performed more stably.

  In the first polishing island 20a, the second polishing island 20b, and the third polishing island 20c, the polishing portions 21 adjacent to the slits 10a are arranged in a straight line in the radial direction as shown in FIG. By arranging the polishing portion 21 adjacent to the slit 10a in a straight line in this manner, when the polishing pad 1 is cut linearly along the slit 10a, the polishing portion 21 is cut together to cause a defect. Can be suppressed.

  In order to arrange the polishing portions 21 adjacent to the slit 10a in a straight line in the radial direction while making the first polishing islands 20a, the second polishing islands 20b, and the third polishing islands 20c have the same shape, the polishing portions 21 near the slits 10a are required. It is advisable to adjust the spacing between the columns. For example, in the polishing pad 1 shown in FIG. 1, in each polishing island region, as shown in FIG. The spacing between columns has been adjusted.

  Further, as shown in FIG. 2, the polishing portion 21 adjacent to the inner and outer arcs of the first polishing island 20a, the second polishing island 20b, and the third polishing island 20c is provided so as not to cause a defect. . More specifically, when the polishing sections 21 are arranged in a staggered manner as described above, the inner and outer arcs and the polishing section 21 are not arranged at positions where the polishing sections 21 overlap in plan view.

  The lower limit of the average pitch (L in FIG. 3) of the polishing sections 21 arranged in one row is preferably 4.5 mm, more preferably 5 mm. On the other hand, the upper limit of the average pitch L is preferably 6.5 mm, more preferably 5.5 mm. If the average pitch L is less than the lower limit, the average area of the top surface of the polishing unit 21 cannot be sufficiently secured, and the polishing unit 21 may easily fall during polishing. Conversely, when the average pitch L exceeds the upper limit, the width of the groove 22 between the adjacent polishing portions 21 becomes large, and the substrate 10 may be easily warped.

  The lower limit of the minimum interval (D in FIG. 3) between the polishing units 21 is preferably 0.3 mm, more preferably 0.5 mm. On the other hand, the upper limit of the minimum distance D is preferably 2.5 mm, more preferably 2 mm. If the minimum distance D is less than the lower limit, the average area of the top surface of the polishing section 21 cannot be sufficiently secured, and the polishing section 21 may easily fall during polishing. Conversely, if the minimum distance D exceeds the upper limit, the width of the groove 22 between the adjacent polishing portions 21 increases, and the base 10 may be likely to warp. On the other hand, by setting the minimum distance D between the polishing portions 21 within the above range, an appropriate contact area with the workpiece and the polishing pressure can be secured, so that the polishing rate of the polishing pad 1 is further increased. Can be.

The lower limit of the area of the top surface of the polishing section 21 is 10 mm ² , and more preferably 12 mm ² . On the other hand, the upper limit of the area of the top surface of the polishing unit 21 is 27.5 mm ^2, more preferably 25 mm ^2, more preferably 20 mm ^2. If the average area of the top surface of the polishing section 21 is less than the lower limit, the bottom area of the cylindrical polishing section 21 is also small, so that the polishing section 21 cannot sufficiently adhere to the base material 10 and falls during polishing. It may be easier. Conversely, if the average area of the top surface of the polishing section 21 exceeds the upper limit, the polishing pressure may be dispersed and the polishing rate may be reduced, or the substrate 10 may be easily warped.

  The lower limit of the area occupation ratio of the plurality of polishing units 21 to the entire polishing island 20 is preferably 40%, more preferably 43%, and even more preferably 45%. On the other hand, the upper limit of the area occupancy is preferably 65%, more preferably 61%, and still more preferably 60%. If the area occupation ratio is less than the lower limit, the pressure applied during polishing is excessively concentrated on the narrow polishing portion 21, and the polishing portion 21 may be separated from the base material 10. Conversely, if the area occupancy exceeds the upper limit, the contact area of the polishing island 20 with the workpiece during polishing increases, and the polishing rate may decrease due to frictional resistance.

  The lower limit of the average thickness of the polishing islands 20 (the average height of the plurality of cylindrical polishing portions 21) is preferably 0.5 mm, more preferably 0.8 mm, and still more preferably 1 mm. On the other hand, the upper limit of the average thickness of the polishing islands 20 is preferably 2 mm, more preferably 1.8 mm. If the average thickness of the polishing island 20 is less than the lower limit, the durability of the polishing island 20 may be insufficient, and the life of the polishing pad 1 may be shortened. Conversely, if the average thickness of the polishing islands 20 exceeds the above upper limit, the aspect ratio of the polishing portion 21 increases, and the polishing occurs under the influence of the load applied to the interface between the polishing islands 20 and the base material 10 due to the moment generated during polishing. There is a possibility that the portion 21 is likely to fall down, and a manufacturing cost of the polishing pad 1 may be increased.

(groove)
The groove 22 not only controls the area occupancy of the polishing section 21 according to its size in plan view, but also discharges polishing powder generated by polishing to the outside of the polishing pad 1.

  In the polishing pad 1, the bottom surface of the groove 22 is formed by the surface of the base material 10 as shown in FIG. By configuring the bottom surface of the groove 22 with the surface of the base material 10 in this manner, the ability to discharge the polishing powder can be enhanced. In addition, the polishing pad 1 has a life when the polishing portion 21 is worn by use and its top surface approaches the bottom surface of the groove 22. However, the life of the polishing pad 1 is reduced by forming the bottom surface of the groove 22 with the surface of the base material 10. Can be extended.

  On the other hand, it is also possible to adopt a configuration in which the depth of the groove 22 is smaller than the average thickness of the polishing portion 21 and the groove 22 does not reach the surface of the base material 10. With such a configuration, the lower portions of the plurality of polishing sections 21 are integrated, so that the polishing sections 21 can be made hard to fall.

  In this case, the depth of the groove 22 can be 50% or more of the average height of the polishing part 21. If the depth of the groove 22 is less than the above lower limit, the life of the polishing pad 1 may be too short.

  In addition, the polishing portion 21 in the region serving as the bottom surface of the groove 22 in a plan view may include the same abrasive grains 23 and binder 24 as the polishing portion 21, or may include only the binder 24. Since the region serving as the bottom surface of the groove 22 does not substantially contribute to polishing, the amount of the abrasive grains 23 required for the polishing pad 1 can be reduced without reducing the polishing rate by forming only the binder 24, The manufacturing cost of the polishing pad 1 can be reduced.

<Adhesive layer>
The adhesive layer 30 is a layer for supporting the polishing pad 1 and fixing the polishing pad 1 to a support for mounting the polishing pad on a 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 a pressure-sensitive adhesive that is a replaceable adhesive.

  The adhesive used for the adhesive layer 30 is preferably an adhesive. By using a pressure-sensitive adhesive as the adhesive used 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. Examples of such an adhesive include, but are not particularly limited to, an acrylic adhesive, an acrylic-rubber adhesive, a natural rubber adhesive, a synthetic rubber adhesive such as a butyl rubber adhesive, a silicone adhesive, and a polyurethane adhesive. Agents and the like.

  The lower limit of the average thickness of the adhesive layer 30 is preferably 0.05 mm, more preferably 0.1 mm. On the other hand, the upper limit of the average thickness of the adhesive layer 30 is preferably 0.3 mm, more preferably 0.2 mm. If the average thickness of the adhesive layer 30 is less than the above lower limit, the adhesive strength may be insufficient, and the polishing pad 1 may be separated from the support. Conversely, if the average thickness of the adhesive layer 30 exceeds the above upper limit, workability may be reduced, for example, the thickness of the adhesive layer 30 may hinder the cutting of the polishing pad 1 into a desired shape. .

<Manufacturing method of polishing pad>
The polishing pad 1 can be manufactured by a manufacturing method including, for example, a preparation step, a polishing island forming step, and an adhesive layer attaching step.

(Preparation process)
In the above-mentioned preparation step, a composition for polishing islands containing abrasive grains 23 and a binder 24 is prepared.

  Specifically, a composition for polishing islands containing a material for forming the abrasive grains 23 and the binder 24 is prepared as a coating liquid. In addition, since the content of the abrasive grains 23 in the solid content is the content of the abrasive grains 23 in the polishing unit 21 after the production, the amount of the solid content is adjusted so that the content in the polishing unit 21 becomes a desired value. Decide appropriately.

  Further, a diluent such as water or alcohol is added to control the viscosity and fluidity of the coating liquid. By this dilution, a part of the abrasive grains 23 included in the polishing section 21 can be projected from the surface of the binder 24. That is, by adding the diluent, the thickness of the binder 24 decreases when the polishing island composition is dried in the polishing island forming step, and the protrusion amount of the abrasive grains 23 can be increased. Therefore, a high polishing rate can be developed from the beginning of polishing by this dilution.

(Polishing island formation process)
In the polishing island forming step, the polishing islands 20 are formed by printing the polishing island composition prepared in the preparation step. The polishing island forming step includes a coating step and a drying step.

[Coating process]
In the coating step, the polishing island composition is coated on the surface of the substrate 10.

  Specifically, using the coating solution prepared in the preparation step, a polishing island 20 having a plurality of polishing portions 21 and grooves 22 provided between the polishing portions 21 is formed on the surface of the base material 10 by a printing method. Form. In order to form the groove 22, a mask having a shape corresponding to the shape of the groove 22 is prepared, and the coating liquid is printed through the mask. As this printing method, for example, screen printing, metal mask printing, or the like can be used.

  As the printing mask, a SUS or fluororesin mask is preferable. Since the SUS or fluororesin mask can be made thicker, the polished portion 21 having a large average thickness can be easily produced.

  The height of the polishing section 21 can be adjusted mainly by the thickness of the mask and the coating amount. Therefore, in this coating step, the coating amount of the polishing island composition may be adjusted so that the average height of the polishing portion 21 is a desired value.

(Drying process)
In the drying step, the coating liquid (composition for polishing islands) after the above-mentioned coating step is heated and dried. The coating liquid is hardened by the heating and drying, and the polishing island 20 is formed. This drying step is performed after removing the mask.

  The lower limit of the heating temperature in the drying step is preferably 80 ° C, more preferably 100 ° C. On the other hand, the upper limit of the heating temperature is preferably 300 ° C, more preferably 200 ° C. When the heating temperature is lower than the lower limit, the polishing island composition is not sufficiently cured, the amount of wear increases, and the life of the polishing pad 1 may be shortened. Conversely, if the heating temperature exceeds the upper limit, the polishing section 21 may be deteriorated by heat.

  The heating time in the drying step depends on the heating temperature, but the lower limit of the heating time is preferably 2 hours, more preferably 2.5 hours. On the other hand, the upper limit of the heating time is preferably 20 hours, and more preferably 18 hours. If the heating time is shorter than the lower limit, the polishing island composition is not sufficiently cured, the amount of wear increases, and the life of the polishing pad 1 may be shortened. Conversely, if the heating time exceeds the upper limit, the manufacturing efficiency of the polishing pad 1 may be reduced.

(Adhesive layer sticking process)
In the adhesive layer attaching step, the adhesive layer 30 is laminated on the back surface side of the base material 10. Specifically, for example, a tape-shaped adhesive layer 30 formed in advance is attached to the back surface of the base material 10.

<Advantages>
In the polishing pad 1, since the polishing portion 21 has a columnar shape, the polishing portion 21 is not easily chipped or cracked even when the polishing pressure is increased, and the polishing can be stably performed. The polishing pad 1 has an area of 10 mm ² or more and 25 mm ² or less of the top surface of the polishing section 21, so that the polishing pressure can be effectively reduced by the polishing section 21 while securing adhesion to the substrate 10. The polishing rate can be increased.

[Other Embodiments]
The present invention is not limited to the above-described embodiment, and can be embodied with various changes and improvements in addition to the above-described aspects.

  In the above embodiment, the case where the base material has the slit in which the polishing island is not formed on the surface has been described. However, the slit is not an essential component and can be omitted.

  Further, in the above embodiment, the case where the position of the polishing unit in the adjacent row is shifted by a half pitch from the position of the polishing unit in one row is described. However, the shift of the position is not limited to the half pitch. / 3 pitch. In this case, as the arrangement of the plurality of polishing units, the same pattern is repeated every three rows.

  In the above embodiment, the case where the plurality of polishing units are staggered has been described, but the plurality of polishing units need not be staggered. For example, the plurality of polishing units may be regularly arranged on the grid points.

  In the above embodiment, the case where the polishing pad has the adhesive layer has been described, but the adhesive layer is not an essential component and can be omitted. When the polishing pad does not have an adhesive layer, the step of attaching the adhesive layer in the method for manufacturing a polishing pad is omitted.

  Alternatively, as shown in FIG. 5, the polishing pad 2 is provided on the other surface of the base material 10 with a support 40 further laminated via the adhesive layer 30 and a second support further laminated via the support 40. An adhesive layer 31 may be provided. When the polishing pad 2 includes the support 40, handling of the polishing pad 2 is facilitated. The constituent elements of the polishing pad 2 other than the support 40 and the second adhesive layer 31 are the same as those of the polishing pad 1 shown in FIG.

(Support)
Examples of the main component of the support 40 include thermoplastic resins such as polypropylene, polyethylene, polytetrafluoroethylene, and polyvinyl chloride, and engineering plastics such as polycarbonate, polyamide, and polyethylene terephthalate. By using such a material as the main component of the support 40, the support 40 has flexibility, the polishing pad 2 follows the surface shape of the workpiece, and the polishing surface and the workpiece come into contact with each other. The polishing rate is further improved because the polishing becomes easier. Above all, as a main component of the support 40, polyvinyl chloride is preferable from the viewpoint of adhesiveness with the adhesive layer 30 and the second adhesive layer 31.

  The shape and size of the support 40 are appropriately determined according to the shape and size of the platen of the polishing machine to be used. It is also possible to adopt a configuration in which a plurality of supports 40 juxtaposed on a plane like the above-described base material 10 are supported on a surface plate of a polishing machine.

  The lower limit of the average thickness of the support 40 is preferably 0.5 mm, more preferably 0.8 mm. On the other hand, the upper limit of the average thickness of the support 40 is preferably 3 mm, more preferably 2 mm. If the average thickness of the support 40 is less than the lower limit, the strength of the polishing pad 2 may be insufficient. Conversely, if the average thickness of the support 40 exceeds the upper limit, the support 40 may be difficult to attach to the surface plate of the polishing machine, and the flexibility of the support 40 may be insufficient.

(Second adhesive layer)
The same adhesive as the adhesive layer 30 can be used for the second adhesive layer 31. Further, the second adhesive layer 31 can have the same average thickness as the adhesive layer 30.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
A diamond abrasive (average particle diameter: 61 μm) and an epoxy resin as a binder were mixed, and the content of the diamond abrasive in the solid content was adjusted to 10% by volume to obtain a coating liquid. Further, a polycarbonate plate having an average thickness of 500 μm was prepared as a substrate.

The surface of the substrate was coated by printing using the above coating liquid. As a printing pattern, as shown in FIG. 1, a pattern having three regions of a first polishing island 20a, a second polishing island 20b, and a third polishing island 20c of the same shape was used. The polishing portion in each polishing island region had a diameter of 4 mm (12.56 mm ² ) and an area occupancy of 45%. The average pitch between the polishing parts was 4.98 mm, and the minimum distance between the polishing parts was 0.98 mm, except for the row group R whose spacing was adjusted. The number of polished portions in each polished island region was 3,432. The coating amount was adjusted so that the average height of the polished portion was 1 mm.

  The coating liquid was cured by drying at 120 ° C. for 16 hours in an oven. Thus, the polishing pad of Example 1 was obtained.

[Comparative Example 1]
A polishing pad of Comparative Example 1 was obtained in the same manner as in Example 1 except that the printing pattern was configured as described below.

As a printing pattern, as shown in FIG. 1, a pattern having three regions of a first polishing island 20a, a second polishing island 20b, and a third polishing island 20c of the same shape was used. The polishing portion in each polishing island region had a diameter of 6 mm (28.26 mm ² ) and an area occupancy of 40%. The average pitch between the polishing parts was 8.61 mm, and the minimum distance between the polishing parts was 2.61 mm, except for the row group R whose spacing was adjusted. In addition, the number of polishing portions in each polishing island region was 1180.

[Polishing conditions]
Using the polishing pads obtained in Example 1 and Comparative Example 1, a glass substrate (Gorilla 3 glass, thickness 1 mm, mirror surface) was polished. Polishing was performed under the conditions of an upper platen rotation speed of 550 rpm, a lower platen rotation speed of 550 rpm, and a carrier rotation speed of 0.6 rpm. At this time, 15 liters of a coolant obtained by diluting “CG50-P” manufactured by Noritake Co., Ltd. 30 times was supplied as a coolant.

[Evaluation]
After polishing for 5 seconds under the above conditions, the thickness (removed amount) and surface roughness (Ra) of the removed glass substrate were measured. Table 1 shows the results. Note that a micrometer was used to measure the thickness of the glass substrate. The surface roughness (Ra) was measured using a contact surface roughness meter (manufactured by Mitutoyo Corporation) in accordance with the method described in JIS-B-0601: 2001.

From the results of Table 1, Example 1 the area of the top surface of the polishing portion is 10 mm ² or more 25 mm ² or less, the area of the top surface of the polishing portion is compared with Comparative Example 1 in which more than 25 mm ^2, the surface roughness ( Ra) are the same and the removal amount is large. From this, it is understood that the polishing rate can be increased by setting the area of the top surface of the polishing portion to 10 mm ² or more and 25 mm ² or less.

  The polishing pad of the present invention has an excellent polishing rate especially under the condition that the rotation speed of the platen of the polishing machine and the polishing pressure are increased. Therefore, by using the polishing pad, the processing time can be reduced and the production efficiency of the product can be increased.

1, 2 Polishing pad 10 Base material 10a Slit 20 Polishing island 20a First polishing island 20b Second polishing island 20c Third polishing island 21 Polishing unit 22 Groove 23 Abrasive grain 24 Binder 30 Adhesive layer 31 Second adhesive layer 40 Support M Center R of polishing part R Row group L whose spacing is adjusted Pitch D Minimum spacing

Claims (5)

A substrate,
A polishing island laminated on one surface of the substrate and containing abrasive grains and a binder,
The polishing island has a plurality of columnar polishing portions whose central axis is orthogonal to the one surface,
Polishing pad area of the top surface of the polishing portion is 10 mm ² or more 27.5 mm ² or less.   2. The polishing pad according to claim 1, wherein an area occupation ratio of the plurality of polishing portions to an entire polishing island is 40% or more and 65% or less.   The polishing pad according to claim 1 or 2, wherein the plurality of polishing portions are arranged in a staggered manner.   4. The polishing pad according to claim 1, wherein a minimum distance between the polishing portions is 0.3 mm or more and 2.5 mm or less. 5. The polishing pad according to any one of claims 1 to 4, wherein an average thickness of the polishing island is 0.5 mm or more and 2 mm or less.

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