JP5587636B2 - Polishing pad - Google Patents

Description

  The present invention relates to a polishing pad, and in particular, includes a soft plastic sheet formed by a wet coagulation method and having a polishing surface on one side, a substrate disposed on the other side of the soft plastic sheet, a soft plastic sheet and a substrate. The present invention relates to a polishing pad comprising an adhesive layer to be bonded.

  Conventional materials such as liquid crystal glass, glass discs, photomasks, silicon wafers, computer controlled displays (CCDs), and cover glasses have been polished for the precision required for the surface. It has been broken. Examples of the polishing process include various techniques ranging from rough polishing for rough polishing to final polishing for high-precision polishing, and in any case, polishing pads are widely used.

  As the polishing pad, a suede type polishing pad having a nap layer in which pores (foaming) are continuously formed by a wet coagulation method is used. In a suede type polishing pad, the skin layer (skin layer) formed on the surface by wet coagulation may be ground and removed depending on the material of the object to be polished and the required surface accuracy. However, for the objects to be polished as described above, the required quality from the user side is increasing, and there is a demand for a polishing pad that can perform highly accurate precision polishing. For example, for the purpose of polishing a semiconductor wafer with high accuracy, a technique for determining the lower limit of the thickness of the nap layer is disclosed (see Patent Document 1).

  In order to realize high-precision surface flatness of an object to be polished, it is not sufficient to determine the thickness of the nap layer. It is effective to increase the hardness and the compression rate of the polishing pad. However, if the hardness is too high (too hard), the flexibility, which is a merit of the suede type, is impaired, so that the workpiece is scratched (scratched), and the flatness is lowered. On the other hand, if the hardness is too low (too soft), roll-off occurs where the outer edge (end) of the workpiece is excessively ground and removed from the center, resulting in flatness in the work surface of the workpiece. It becomes difficult to secure sex. In order to avoid such problems and improve the accuracy of the surface and parallel / flatness of the center and outer edge of the object to be polished, the hardness of the polished surface can be improved by combining artificial leather with different hardness. A technique of a polishing pad having a different shape is disclosed (for example, see Patent Document 2).

JP 2002-059356 A JP 2009-184084 A

  However, although the technique of Patent Document 2 can improve the flatness, since the low-hardness artificial leather and the high-hardness artificial leather are bonded together, the abrasive grains are applied to the workpiece in the high-hardness region. There is a problem that it is rubbed and scratches occur. As described above, it is required to make the polishing pad soft in order to suppress scratches, while it is required to make it hard to suppress roll-off. Therefore, if a polishing pad having a locally different rigidity can be obtained while the surface (polishing surface) for polishing the workpiece of the polishing pad is made of the same material, it is possible to satisfy conflicting requirements. Become.

  In view of the above-described case, an object of the present invention is to provide a polishing pad that can make flatness uniform while suppressing scratches on an object to be polished.

In order to solve the above problems, the present invention provides a soft plastic sheet formed by a wet coagulation method and having a polished surface on one side, a substrate disposed on the other side of the soft plastic sheet, and the soft plastic sheet And a pressure-sensitive adhesive layer that bonds the base material, and the base material is smaller than the main material and has a plastic sheet-like main material formed such that a plurality of grooves or dents form a predetermined pattern. And having at least one kind of a plurality of sub-materials having hardness and thin thickness, the sub-materials are disposed in the grooves or depressions formed in the main material, and the entire surface on one side is the adhesive layer It is a polishing pad characterized by contacting.

In the present invention, since the secondary material of the base material is thinner than the main material, the entire surface on one side of the base material is in contact with the pressure-sensitive adhesive layer, thereby supporting the flexible plastic sheet as a whole base material. Since the secondary material having a hardness smaller than that of the main material is arranged in a groove or a depression formed in the main material so as to form a predetermined pattern, the pressing force applied to the abrasive particles supplied to the polishing surface side during the polishing process is reduced. Since it becomes small in the disposed portion and the abrasive particles easily move, the polishing liquid circulation property on the polishing surface is ensured, and the flatness can be made uniform while suppressing scratches on the object to be polished.

In this case, in the base material, the secondary material may be disposed on the one surface side of the main material, and the one surface side of the main material and the secondary material may form the same plane . The predetermined pattern of the secondary material arranged on the main material can be discrete, striped, latticed or concentric. In the base material, a groove or a recess formed in the main material may be filled with a resin that forms the secondary material. Moreover, it is good also considering the thickness from the surface contact | abutted to the adhesive layer of a submaterial as 50% or more with respect to the thickness of a base material. At this time, the thickness of a base material can be made into the range of 50 micrometers-2000 micrometers. Further, the groove can have a width in the range of 0.5 mm to 10 mm, and the distance between the centers of adjacent grooves can be in the range of 1 mm to 200 mm. In the base material, the main material can be at least one selected from polyethylene terephthalate, polyethylene and polyvinyl chloride, and the secondary material can be an elastomer. The soft plastic sheet may be made of polyurethane resin.

According to the present invention, since the secondary material of the base material is thinner than the main material, the entire surface on one side of the base material is in contact with the adhesive layer, so that the flexible plastic sheet can be supported as a whole base material. In addition, since the secondary material having a hardness smaller than that of the main material is arranged in a groove or a depression formed in the main material so as to form a predetermined pattern, the pressing force applied to the abrasive particles supplied to the polishing surface side during the polishing process is reduced. Since it becomes small at the portion where the material is arranged and the abrasive particles easily move, the polishing liquid circulation property on the polishing surface is ensured, so that the flatness can be made uniform while suppressing scratches on the object to be polished. The effect that can be obtained.

It is sectional drawing which shows typically the polishing pad of embodiment to which this invention is applied. It is a top view which shows typically the positional relationship of the main material part and submaterial part in the surface by the side of the urethane sheet of the base material which comprises a polishing pad, (A) is the base | substrate by which the submaterial part was arrange | positioned concentrically. (B) is a base material in which the sub-material portions are arranged in a grid, (C) is a base material in which the sub-material portions are arranged in stripes, and (D) is a circular sub-material portion concentrically. Substrates arranged so as to be aligned, (E) is a substrate arranged so that circular sub-material portions are aligned in a grid pattern, and (F) is a rectangular sub-material portion aligned in a grid pattern. Each of the substrates arranged in this manner is shown. It is explanatory drawing which illustrates typically the difference in the pressing force applied to a polishing pad at the time of the polishing process of the to-be-polished object by a polishing pad, (A) is at the time of the polishing process by the polishing pad of embodiment, (B) is conventional grinding | polishing. The polishing process with the pad is shown.

  Hereinafter, embodiments of a polishing pad to which the present invention is applied will be described with reference to the drawings.

<Configuration>
As shown in FIG. 1, the polishing pad 10 of this embodiment has a urethane sheet 2 as a soft plastic sheet made of polyurethane resin produced by a wet coagulation method.

  The urethane sheet 2 has a skin layer 2a formed at the time of production by a wet coagulation method on one side, and has a nap layer 2b on the inner side of the skin layer 2a. The skin layer 2a is formed in a fine microporous shape, and the surface constitutes a polishing surface P for polishing the object to be polished. The surface opposite to the skin layer 2a (hereinafter referred to as the back surface) is buffed so that the thickness of the urethane sheet 2 is uniform. That is, the thickness of the urethane sheet 2 is made uniform by performing the buffing process.

In the nap layer 2b, cells (pores) 5 that are vertically long and rounded in the thickness direction (longitudinal direction in FIG. 1) of the urethane sheet 2 are distributed in a substantially uniform manner. It is formed with. The length in the longitudinal direction of the cell 5 varies within the range of the thickness of the urethane sheet 2. The cell 5 is formed such that the hole diameter on the polishing surface P side is smaller than the hole diameter on the back surface side. That is, the cell 5 has a smaller diameter on the polishing surface P side than on the back surface side. The polyurethane resin between the cells 5 is formed in a microporous shape in which micropores (not shown) having a pore diameter smaller than that of the cells 5 are formed. The fine pores of the skin layer 2a, the cells 5 of the nap layer 2b, and the fine pores (not shown) are communicated in a mesh pattern with communication holes (not shown). That is, the urethane sheet 2 has a continuous foam structure. For the urethane sheet 2, a soft polyurethane resin having a modulus of 30 MPa or less is used. Moreover, in the urethane sheet 2, thickness T1 is adjusted to the range of 200-2000 micrometers, and bulk density is adjusted to 0.3 g / cm < ³ > or less. The thickness of the urethane sheet 2 can be adjusted by conditions during wet coagulation or buffing, and the bulk density can be adjusted by setting conditions for cell formation. In such a urethane sheet 2, the Shore A hardness is in the range of 5 to 60 degrees.

  Moreover, in the polishing pad 10, the one surface side of the base material 8 is bonded to the back surface side of the urethane sheet 2 via the adhesive layer 7a. The base material 8 has an adhesive layer 7b on the other surface side in order to attach the polishing pad 10 to a polishing machine (polishing apparatus). The pressure-sensitive adhesive layer 7 b is covered with a release paper 9 on the surface opposite to the substrate 8. As the pressure-sensitive adhesives for the pressure-sensitive adhesive layers 7a and 7b, acrylic, urethane, and epoxy pressure-sensitive adhesives can be used, respectively, and the pressure-sensitive adhesive layer 7a and the pressure-sensitive adhesive layer 7b may be the same pressure-sensitive adhesive. It may be different. In this example, both the pressure-sensitive adhesive layers 7a and 7b are formed of an acrylic pressure-sensitive adhesive. In this example, the base material 8 also has a function of supporting the entire polishing pad 10.

  The base material 8 is made of a plastic resin-made sheet-like main material portion 8a (main material) and a sub-material portion 8b (sub-material) formed of a resin having a Shore A hardness smaller than the main material portion 8a. Have. The main material portion 8a can be made of at least one flexible film selected from polyethylene terephthalate (hereinafter abbreviated as PET), polyethylene (PE) and polyvinyl chloride (PVC). An elastomer can be used for 8b. Examples of the elastomer include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene terpolymer (EPDM), silicone rubber, fluorine-based resin, and the like. Can do. It is also possible to make a foam by mixing a foaming agent with an elastomer. The Shore A hardness is about 70 to 100 degrees for the main material portion 8a and about 10 to 80 degrees for the auxiliary material portion 8b. In this example, a PET film is used as the main material portion 8a, and silicon rubber is used as the auxiliary material portion 8b. The main material portion 8a is formed with a plurality of grooves on the surface side to be bonded to the urethane sheet 2, and the grooves are filled with a resin for forming the auxiliary material portion 8b. As shown in FIG. 2A, on the surface side of the base material 8 to be bonded to the urethane sheet 2, the concentric groove formed in the main material portion 8a is filled with the resin of the sub-material portion 8b. That is, the sub-material portions 8b are equally arranged so as to form a concentric pattern on the main material portion 8a.

  As shown in FIG. 1, one surface side of the main material portion 8a and the auxiliary material portion 8b is in contact with the adhesive layer 7a. The base material 8 has a thickness T2 in the range of 50 to 2000 μm. That is, the thickness of the main material portion 8a is the same as the thickness T2 of the base material 8a. The secondary material portion 8b has a thickness smaller than that of the main material portion 8a, and the thickness t1 from the surface in contact with the adhesive layer 7a is adjusted to 50% or more with respect to the thickness T2 of the base material 8. Yes. In the base material 8 having such a main material portion 8a and the auxiliary material portion 8b, the surface side in contact with the pressure-sensitive adhesive layer 7a forms the same plane. The width of the secondary material portion 8b (width of the groove formed in the main material portion 8a) W1 is adjusted to a range of 0.5 to 10 mm, and the distance between the centers of the adjacent secondary material portions 8b (distance between the centers of the grooves). ) W2 is adjusted in the range of 1 to 200 mm. That is, when the groove is formed in the main material portion 8a, the thickness t1 and the width of the auxiliary material portion 8b are adjusted by adjusting the depth from the surface in contact with the adhesive layer 7a, the width of the groove, and the distance between the centers. W1 and the center-to-center distance W2 can be adjusted.

<Manufacturing>
The polishing pad 10 is manufactured by buffing the urethane sheet 2 produced by the wet coagulation method and then bonding the separately produced base material 8 and the urethane sheet 2 together. In the wet coagulation method, a preparation process for preparing a polyurethane resin solution, a polyurethane resin solution is continuously applied to a film-forming substrate, and the polyurethane resin solution is coagulated in an aqueous coagulation solution to regenerate the polyurethane resin into a sheet. The urethane sheet 2 is produced through a washing / drying step of washing and drying the regenerated polyurethane resin. In the production of the base material 8, concentric grooves are formed in the sheet of the main material portion 8a, and the resin of the auxiliary material portion 8b is filled in the grooves. Hereinafter, the production of the urethane sheet 2, the production of the base material 8, and the bonding will be described in this order.

(Production of urethane sheet 2)
In the preparation step, the polyurethane resin is dissolved by mixing the polyurethane resin, a water-miscible organic solvent capable of dissolving the polyurethane resin, and an additive. As the organic solvent, N, N-dimethylformamide (hereinafter abbreviated as DMF), N, N-dimethylacetamide (DMAc), or the like can be used. In this example, DMF is used. As the polyurethane resin, a resin having a modulus of 30 MPa or less is selected from polyester, polyether, polycarbonate, and the like, and is dissolved in DMF so that the polyurethane resin becomes 30% by weight, for example. As the additive, a pigment such as carbon black for controlling the size and amount (number) of the cells 5, a hydrophilic activator for promoting cell formation, a hydrophobic activator for stabilizing regeneration of the polyurethane resin, and the like are used. it can. The obtained solution is defoamed under reduced pressure to prepare a polyurethane resin solution.

  In the regeneration step, the polyurethane resin solution prepared in the preparation step is continuously applied to the film-forming substrate, and the polyurethane resin solution is solidified in an aqueous coagulating liquid to regenerate the polyurethane resin into a sheet. The polyurethane resin solution is applied to the band-shaped film-forming substrate at a normal temperature by a coating apparatus so as to have a uniform thickness. In this example, a knife coater is used as the coating device. At this time, the application thickness (application amount) of the polyurethane resin solution is adjusted by adjusting the gap (clearance) between the knife coater and the film forming substrate. In this example, in order to make the thickness of the urethane sheet obtained into the above-mentioned range, the coating thickness is adjusted to a range of 500 to 2000 μm. Although a flexible film, a nonwoven fabric, a woven fabric, or the like can be used as the film forming substrate, in this example, the film forming substrate is described as a PET film.

  The polyurethane resin solution applied to the film forming substrate is guided into a coagulating liquid (water-based coagulating liquid) whose main component is water, which is a poor solvent for the polyurethane resin. As the coagulation liquid, an organic solvent such as DMF or DMAc can be mixed with water, but in this example, water is used. In the coagulation liquid, first, micropores constituting the skin layer 2a are formed on the surface side of the applied polyurethane resin solution over a thickness of about several μm. Thereafter, the polyurethane resin is regenerated into a sheet shape by the progress of substitution between the DMF in the polyurethane resin solution and the coagulating liquid. By removing DMF from the polyurethane resin solution and replacing DMF and the coagulating liquid, cells 5 and micropores (not shown) are formed in the polyurethane resin inside the skin layer 2a. A communication hole (not shown) communicating in a mesh shape is formed. At this time, since the PET film of the film formation substrate does not allow water to permeate, desolvation occurs on the surface side (skin layer 2a side) of the polyurethane resin solution, and cells 5 having a larger film formation substrate side than the surface side are formed. The

  In the cleaning / drying step, the regenerated band-shaped (long-length) film-forming resin is cleaned and then dried. That is, after the film-forming resin is peeled from the film-forming substrate, it is washed in a cleaning liquid such as water to remove DMF remaining in the film-forming resin. After cleaning, the film forming resin is dried. In this example, a cylinder dryer having a cylinder having a heat source is used for drying the film-forming resin. The film-forming resin is dried by passing along the peripheral surface of the cylinder. The film-forming resin after drying is rolled up.

  When the buffing is performed, the surface opposite to the skin layer 2a of the film-forming resin dried in the cleaning / drying process, that is, the back surface is applied. In a film-forming resin formed by a wet coagulation method, thickness variation occurs when a polyurethane resin solution is applied or when the polyurethane resin is regenerated. By pressing a pressure welding jig having a flat surface on the surface of the film forming resin on the skin layer 2a side, irregularities appear on the back surface side of the film forming resin. This unevenness is removed by buffing. In this example, since the continuously formed film-forming resin has a belt shape, the buffing process is continuously performed while pressing the pressing roller. The urethane sheet 2 formed by buffing the film-forming resin has a uniform thickness.

(Preparation of base material 8)
In the production of the substrate 8, a PET film having a thickness T2 is prepared as the main material portion 8a. Two ring-shaped grooves are formed concentrically on one surface side of the main material portion 8a. For forming the groove, for example, a groove forming apparatus that can move three-dimensionally while gripping the upper end of a rod-shaped grinding jig whose lower end is formed in a file shape and rotating the grinding jig is used. it can. The width of the groove can be adjusted by the diameter of the grinding jig, and the depth of the groove can be adjusted by the amount of movement in the vertical direction. Moreover, the concentric groove | channel which adjusted the distance between centers by the movement in a horizontal surface can be formed. The groove formed in the main material portion 8a is filled with silicon rubber as the auxiliary material portion 8b having a Shore A hardness smaller than that of the main material portion 8a. In filling the groove, for example, a melt or a solvent solution due to the heat of the resin is poured into the groove and solidified by cooling or solvent evaporation. In the obtained base material 8, the secondary material portion 8b having the width W1 and the thickness t2 is arranged to be separated from the main material portion 8a by the center distance W2.

(Lamination)
The buffed surface (back surface) side of the urethane sheet 2 is bonded to the surface side where the secondary material portion 8 b is disposed on the main material portion 8 a of the base material 8. At this time, the pressure-sensitive adhesive layer 7a is formed on the urethane sheet 2 or the substrate 8, and the urethane sheet 2 and the substrate 8 are bonded together. After bonding the urethane sheet 2 and the base material 8 together, the pressure-sensitive adhesive layer 7 b is formed on the surface of the base material 8 opposite to the urethane sheet 2, and the surface is covered with the release paper 9. The urethane sheet 2, the pressure-sensitive adhesive layer 7 a, the base material 8, the pressure-sensitive adhesive layer 7 b, and the release paper 9 can be securely bonded by sandwiching and pressing between two flat jigs. Then, after cutting into a desired shape such as a circle and a desired size, an inspection is performed to confirm that there is no adhesion of scratches, dirt, foreign matter, etc., and the polishing pad 10 is completed.

  When polishing an object to be polished with the polishing pad 10, for example, a double-side polishing machine having two opposing surface plates is used. A polishing pad 10 is adhered to each of the two surface plates. When adhering the polishing pad 10 to the surface plate, the release paper 9 is removed and the exposed adhesive layer 7b is applied. A polishing liquid (slurry) containing abrasive particles is circulated and supplied between the object to be polished and the polishing pad 10, and at least one surface plate is rotated while applying pressure (polishing pressure) to the object to be polished. Is polished.

<Action etc.>
Next, the operation and the like of the polishing pad 10 of this embodiment will be described.

  Here, in order to make the description of the polishing pad 10 easy to understand, a conventional polishing pad will be described. As shown in FIG. 3B, in the conventional polishing pad 20, the urethane sheet 2 is bonded to the base material 18 made of a uniform material. For this reason, when a polishing pressure (arrow a in the figure) is applied during the polishing process, the urethane sheet 2 is evenly pressed, and the abrasive particles AG supplied between the processed surface S and the polished surface P of the workpiece 70 are polished. Is uniformly pressed to the workpiece 70 side. For this reason, the movement of the abrasive particles AG between the processed surface S and the polished surface P is limited, and the processed surface S may be locally polished. As a result, scratches are likely to occur on the processed surface S of the workpiece 70, and flatness may be impaired. The present embodiment is a polishing pad 10 that can solve these problems.

  In this embodiment, the polishing pad 10 is configured by bonding the urethane sheet 2 and the base material 8 together. The base material 8 has a main material portion 8a and a sub material portion 8b, and the sub material portion 8b has a Shore A hardness smaller than that of the main material portion 8a. In the base material 8, the secondary material part 8b is equally arrange | positioned at the main material part 8a. Since the Shore A hardness is different between the main material portion 8a and the secondary material portion 8b, when a polishing pressure is applied, the pressing applied to the abrasive particles supplied between the processed surface of the workpiece and the polishing surface P of the polishing pad 10 is applied. The pressure differs between the main material portion 8a portion of the base material 8 and the portion where the auxiliary material portion 8b is disposed. That is, as shown in FIG. 3A, when the polishing pressure (arrow a) is applied, the pressing force applied to the abrasive particles AG at the position corresponding to the main material portion 8a (shown in the urethane sheet 2 in the figure). Compared with the large arrow.), The pressing force (small arrow shown in the urethane sheet 2 in the figure) applied to the abrasive particles AG at the position corresponding to the portion where the sub-material portion 8b is disposed is small. For this reason, in the main material portion 8a, the abrasive particles AG are sandwiched between the polishing surface P and the processing surface S, and the polishing action on the processing surface S can be surely exhibited. On the other hand, in the portion where the secondary material portion 8b is disposed, the abrasive particles AG are easily pushed into the urethane sheet 2 side, and move in a direction along the polishing surface P while being sandwiched between the polishing surface P and the processing surface S. It becomes easy. In other words, on the polishing surface P, a region that exhibits a reliable polishing action and a region that ensures the circulation of the slurry are arranged in a predetermined pattern. As a result, the movement of the abrasive particles AG between the polishing pad 10 and the workpiece 70 is equalized, and the local pressing of the abrasive particles AG against the workpiece 70 is reduced. The occurrence of scratches can be suppressed, and the flatness within the processed surface S can be made uniform.

  Moreover, in this embodiment, the submaterial part 8b is arrange | positioned concentrically, and the center distance W2 is adjusted to the range of 1-200 mm. For this reason, since the movement of the abrasive particles AG between the polishing pad 10 and the workpiece 70 is equalized, the flatness can be improved. Further, the secondary material portion 8b is thinner than the main material portion 8a, and the thickness t1 from the surface in contact with the adhesive layer 7a is adjusted to 50% or more with respect to the thickness T2 of the base material 8. . When the ratio of the thickness t1 to the thickness T2 is smaller than 50%, even if the polishing pressure is applied, the difference in the pressing force with respect to the abrasive particles AG becomes small, and the mobility of the abrasive particles AG becomes insufficient. By adjusting the ratio of the thickness t1, the abrasive particles can be easily moved by the secondary material portion 8b having a compression ratio larger than that of the main material portion 8a, that is, softer than the main material portion 8a. On the other hand, the sub-material portion 8b is thinner than the main material portion 8a, so that the main material portion 8a is positioned so as to correspond to the entire polishing surface P. For this reason, the whole base material 8 can exhibit the function of supporting the urethane sheet 2 during polishing. Furthermore, in the secondary material part 8b, the width W1 is adjusted to a range of 0.5 to 10 mm. For this reason, since the width | variety of the part which the abrasive particle AG tends to move is ensured, the flatness of the to-be-polished object 70 can be improved. In the present embodiment, the main material portion 8a and the auxiliary material portion 8b are in contact with the adhesive layer 7a. For this reason, since the whole surface of the base material 8 is bonded to the urethane sheet 2 via the pressure-sensitive adhesive layer 7a, peeling between the base material 8 and the urethane sheet 2 can be suppressed during polishing.

  Furthermore, in this embodiment, the thickness T2 of the base material 8 is adjusted in the range of 50 to 2000 μm, and the thickness T1 of the urethane sheet 2 is adjusted in the range of 0.2 to 2.0 mm. When the thickness T2 of the base material 8 is smaller than 50 μm, the thickness t1 of the secondary material portion 8b disposed on the base material 8 is small, so that the above-described ease of movement of the abrasive particles AG can be sufficiently exhibited. It becomes difficult. On the other hand, if the thickness T2 of the substrate 8 is greater than 2000 μm, the overall thickness of the polishing pad 10 increases, which is not preferable. In addition, if the thickness T1 of the urethane sheet 2 is smaller than 0.2 mm, the size of the formed cell is limited by the thickness T1 even if it is produced by the wet coagulation method. It becomes difficult to demonstrate. On the other hand, if the thickness T1 of the urethane sheet 2 is larger than 2.0 mm, the polyurethane resin solution may not be sufficiently solidified during the production by the wet coagulation method, and the foam structure and the urethane sheet itself may not be sufficiently formed. There is. Therefore, by setting the thickness T2 of the base material 8 and the thickness T1 of the urethane sheet 2 within the above-described ranges, a sufficient effect can be exhibited during polishing without causing inconvenience during production.

  In the present embodiment, as an example of the base material 8, the concentric groove formed in the sheet-like main material portion 8 a is filled with the resin of the secondary material portion 8 b, but the present invention is limited to this. It is not a thing. As the shape of the groove, for example, a lattice shape or a stripe shape can be used instead of the concentric shape. That is, the linear grooves may be formed in a lattice shape as shown in FIG. 2B, or the linear grooves may be formed in a stripe shape as shown in FIG. . In these cases, it goes without saying that the width, depth, and center-to-center distance of the grooves may be adjusted. By filling such a groove with the resin of the secondary material portion 8b, the same effect as in the present embodiment can be obtained. Moreover, it can replace with forming the groove | channel in the main-material part 8a, and can form a hollow by embossing etc. discretely. For example, as shown in FIG. 2 (D), a plurality of circular recesses may be formed so as to be concentrically arranged in the surface on the urethane sheet 2 side, and as shown in FIG. The plurality of depressions may be formed so as to be aligned in a lattice pattern. Instead of the circular depressions, for example, rectangular depressions may be formed so as to be arranged in a lattice pattern as shown in FIG. Furthermore, when the depressions are formed, considering that it is difficult to form the recesses precisely, it is only necessary that the recesses are approximately equal. The effect similar to this embodiment can be acquired by filling such a hollow with resin of the submaterial part 8b.

  In the present embodiment, an example is shown in which the surfaces of the main material portion 8a and the auxiliary material portion 8b that are in contact with the adhesive layer 7a form the same plane, but the present invention is not limited to this. Considering that the secondary material portion 8b is formed by pouring resin into the groove formed in the main material portion 8a, it is expected that the resin will rise slightly in the secondary material portion 8b. Even in this case, by adhering to the urethane sheet 2 via the pressure-sensitive adhesive layer 7a, it is possible to absorb the rising of the secondary material portion 8b due to the elasticity of the pressure-sensitive adhesive layer 7a. Furthermore, in this embodiment, although the example which bonds together the one surface side of the main material part 8a and the submaterial part 8b which formed the same plane, and the back surface side of the urethane sheet 2 via the adhesive layer 7a was shown, this invention Is not limited to this. You may make it arrange | position the submaterial part 8b in the surface side opposite to the urethane sheet 2 of the main material part 8a. This is because, for example, a PET film as a main material part is bonded to the back surface side of the urethane sheet 2 via an adhesive layer 7a, and then a groove or a depression is formed on the surface side opposite to the urethane sheet 2 of the main material part. Can be realized by filling the resin of the secondary material part. Of course, it is preferable that the main material portion and the auxiliary material portion form the same plane. The main material part and the sub-material part which formed the same plane will contact | abut to the adhesive layer 7b. In this case, it is preferable that the thickness from the surface of the secondary material portion that contacts the pressure-sensitive adhesive layer 7b is 70% or more with respect to the thickness of the base material (main material portion).

  Furthermore, in this embodiment, although the example which arrange | positions one kind of submaterial part 8b with respect to the main material part 8a was shown, this invention is not limited to this. The secondary material portion 8b only needs to have a smaller hardness than the main material portion 8a. For example, two or more types of secondary material portions 8b may be arranged. In other words, a plurality of grooves can be filled with different resins. Since the mobility of the abrasive particles AG is improved by the difference in hardness between the main material portion 8a and the secondary material portion 8b, the same effect as in this embodiment can be obtained even if a plurality of resins are used as the secondary material portion 8b. it can. Further, in the present embodiment, an example in which the base material 8 also has a function of supporting the entire polishing pad 10 has been shown, but a support material may be bonded separately from the base material 8. In this case, what is necessary is just to affix a support material on the surface side opposite to the urethane sheet 2 of the base material 8. FIG. The material of the support material is not particularly limited as long as the function of supporting the entire polishing pad 10 can be exhibited.

  Furthermore, in the present embodiment, an example in which the surface opposite to the skin layer 2a of the urethane sheet 2, that is, the back surface side is buffed is shown, but the present invention is not limited to this. For example, instead of buffing the back surface side depending on the type of the object 70 to be polished, the buffing may be performed on the skin layer 2a side. For example, when it is desired to increase the amount of polishing to be removed from the processed surface S of the workpiece 70 by polishing, the inner surface of the urethane sheet 2 is formed by buffing the skin layer 2a. An opening of the formed cell 5 can be formed on the polishing surface P. By forming the opening of the cell 5 on the polishing surface P, the polishing liquid containing the abrasive particles AG is circulated and supplied while being stored in the cell 5. Of course, buffing may be performed on both the skin layer 2a side and the back surface side.

  Furthermore, in the present embodiment, the urethane resin-made urethane sheet 2 produced by the wet coagulation method is illustrated, but the present invention is not limited to this. For example, in addition to the polyurethane resin, a polyethylene resin or the like can be used, and any resin can be used as long as the foamed structure is formed by a wet coagulation method. In addition, for soft plastics, the Japanese Industrial Standard (JIS K6900-1994 Plastics-Terminology) states, “Under specified conditions, the elastic modulus in the bending test, or if it is not applicable, in the tensile test, Since it is defined as “plastic not larger than 70 MPa”, any material satisfying this condition may be used.

  Moreover, in this embodiment, although the example which forms the adhesive layer 7a (the adhesive layer 7b is also the same) which bonds the urethane sheet 2 and the base material 8 with an acrylic adhesive was shown, this invention is based on this. It is not limited. As an adhesive, in addition to acrylic, an adhesive such as urethane or epoxy may be used. Further, as the pressure-sensitive adhesive layer 7a and the pressure-sensitive adhesive layer 7b, for example, it is possible to use a non-support tape that is a double-sided tape in which only the pressure-sensitive adhesive is sandwiched between two release papers without having a supporting base material.

  Next, examples of the polishing pad 10 manufactured according to the present embodiment will be described. A comparative polishing pad manufactured for comparison is also shown.

Example 1
In Example 1, as a base material 8, a concentric groove is formed in a main material portion 8a of a PET film (Shore A hardness 95 degrees) having a thickness T2 of 1.5 mm, a width of 2 mm, a depth of 1.3 mm, and a center. The distance was 5 mm. This groove was filled with a silicon resin (Shore A hardness 30 degrees) as a resin for forming the secondary material portion 8b. The width W1 of the secondary material portion 8b is 2 mm, the thickness t1 is 1.3 mm, and the center distance W2 is 5 mm.

(Comparative Example 1)
In Comparative Example 1, the same procedure as in Example 1 was performed except that a PET film having a thickness T2 of 1.5 mm was used as the substrate 18 as it was. That is, Comparative Example 1 is a conventional polishing pad 20 (see FIG. 3B).

(Polishing performance evaluation)
Using the polishing pad of each Example and Comparative Example, the aluminum substrate for hard disk was polished under the following polishing conditions, and the polishing performance was evaluated by the presence or absence of roll-off and scratch. Roll-off occurs when the outer edge of the object to be polished is excessively polished from the center, and is one of the measurement items for evaluating flatness. As a measuring method, for example, a two-dimensional profile image is obtained within a range of 1.5 mm in the radial direction from a position of 0.5 mm from the outer peripheral end to the center with an optical surface roughness meter. In the obtained two-dimensional profile image, when the radial direction is the X axis and the thickness direction is the Y axis, the values of the Y axis at the coordinate positions of X = 0.5 mm and X = 1.5 mm from the outer peripheral end are Y Leveling correction was performed so that = 0, and the PV value of X = 0.5 to 1.5 mm of the two-dimensional profile image at this time was obtained. For measurement of roll-off, a surface roughness measuring machine (manufactured by Zygo, model number New View 5022) was used, and an average value (Avg) and a maximum value (Max) were obtained. The presence or absence of scratch was determined by visual observation of the polished aluminum substrate. Table 1 below shows the measurement results for the presence or absence of roll-off and scratches.
(Polishing conditions)
Polishing machine used: 9B-5P polishing machine manufactured by Speed Fam Co., Ltd.
Polishing pressure: 90 g / cm ²
Abrasive: Colloidal silica slurry (average particle size: 0.05 μm)
Object to be polished: 95 mmφ hard disk aluminum substrate Polishing time: 300 seconds

  As shown in Table 1, the polishing pad 20 of Comparative Example 1 has an average roll-off value of 7.7 nm and a maximum value of 9.4 nm, and it is difficult to meet the demand for high-precision flatness. Scratches were also observed on the aluminum substrate. On the other hand, in the polishing pad 10 of Example 1, the average value of roll-off is greatly improved to 5.3 nm and the maximum value is 6.8 nm, and the high-precision flatness requirement is sufficiently met. be able to. In addition, no scratches on the aluminum substrate were observed, and it was revealed that excellent polishing performance was exhibited.

  Since the present invention provides a polishing pad that can make the flatness uniform while suppressing scratches on the object to be polished, it contributes to the manufacture and sale of the polishing pad, and thus has industrial applicability. .

P Polished surface 2 Urethane sheet (soft plastic sheet)
7a Adhesive layer 8 Base material 8a Main material part (main material)
8b Secondary material part (secondary material)
10 Polishing pad

Claims (9)

A soft plastic sheet formed by a wet coagulation method and having a polished surface on one side;
A base material disposed on the other side of the soft plastic sheet;
An adhesive layer that bonds the soft plastic sheet and the substrate;
With
The base material is a sheet-like main material having plasticity formed such that a plurality of grooves or depressions form a predetermined pattern, and at least one kind of a plurality of sub-materials having a smaller hardness and thickness than the main material. A polishing pad, wherein the sub-material is disposed in the groove or depression formed in the main material, and the entire surface on one surface is in contact with the pressure-sensitive adhesive layer.   2. The polishing pad according to claim 1, wherein the secondary material is disposed on one surface side of the main material, and the one surface side of the main material and the secondary material forms the same plane. .   The polishing pad according to claim 2, wherein the secondary material arranged in the main material has the predetermined pattern which is discrete, striped, latticed or concentric. 4. The polishing pad according to claim 3, wherein the base material is formed by filling the groove or the depression formed in the main material with a resin that forms the secondary material. 5.   The polishing pad according to claim 2, wherein the sub-material has a thickness from a surface in contact with the pressure-sensitive adhesive layer of 50% or more with respect to the thickness of the base material. The polishing pad according to claim 5 , wherein the substrate has a thickness in the range of 50 μm to 2000 μm. The polishing pad according to claim 4 , wherein the groove has a width in a range of 0.5 mm to 10 mm, and a distance between centers of adjacent grooves is in a range of 1 mm to 200 mm.   2. The polishing pad according to claim 1, wherein the base material is at least one selected from polyethylene terephthalate, polyethylene, and polyvinyl chloride, and the secondary material is an elastomer. The polishing pad according to claim 8 , wherein the soft plastic sheet is made of a polyurethane resin.

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