JP2011200951A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad which makes the flatness of a polishing object uniformed, while suppressing scratches on the polishing object.SOLUTION: This polishing pad 10 includes an urethane sheet 2 by a wet-coagulation method. A base material 8 is stuck to a back surface side of the urethane sheet 2. The base material 8 includes two kinds of sheet members having plasticity and different Shore A hardness. The two kinds of sheet members include each of a plurality of member pieces 8a and a plurality of member pieces 8b. As for the Shore A hardness, the member pieces 8a and the member pieces 8b are set within a range of 80-95° and a range of 5-40°, respectively. In the base material 8, the member pieces 8a and 8b are arranged in grid-shapes to be adjacent to each other in a planar shape viewed from a side of the surface stuck to the urethane sheet 2. When polishing pressure is applied, a difference is produced in a pressing force applied to polishing particles between the polishing object and the polishing pad 10 to make the polishing particles easy to move.

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 they are rubbed, scratches are generated, and area patterns having different hardnesses are transferred to an object to be polished. As described above, it is required to make the polishing pad soft in order to suppress scratches, but it is required to make it hard to improve flatness. 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 for bonding the base material, the base material has at least two kinds of sheet members having plasticity and different Shore hardness, and the sheet members have the same thickness. The polishing pad is characterized in that the sheet members having different Shore hardnesses are adjacent to each other and one side of the sheet member is in contact with the pressure-sensitive adhesive layer.

  In the present invention, since one surface side of the sheet member having the same thickness is in contact with the pressure-sensitive adhesive layer, the soft plastic sheet and the base material can be bonded together while keeping the polished surface flat, and different shores can be used. Since the sheet members of hardness are arranged adjacent to each other, the pressing force applied to the abrasive particles supplied to the polishing surface side during polishing processing varies depending on the shore hardness of the sheet member, and the abrasive particles easily move. Flatness can be made uniform while suppressing scratches on objects.

  In this case, the sheet member of the base material includes a sheet member having a Shore A hardness in the range of 80 degrees to 95 degrees and a sheet member having a Shore A hardness in the range of 5 degrees to 40 degrees. Can do. At this time, it can arrange | position equally so that the sheet | seat member of a base material may form a striped, grid | lattice form, or concentric pattern. Moreover, it is good also considering the thickness of a base material as the range of 50 micrometers-2000 micrometers.

  According to the present invention, since one surface side of the sheet member having the same thickness is in contact with the adhesive layer, the soft plastic sheet and the base material can be bonded together while keeping the polished surface flat, Since the sheet members having different Shore hardnesses are arranged adjacent to each other, the pressing force applied to the abrasive particles supplied to the polishing surface side during polishing processing makes a difference in the Shore hardness of the sheet member, and the abrasive particles easily move. It is possible to obtain an effect that the flatness can be made uniform while suppressing scratches on the object to be polished.

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 2 types of sheet members from which the Shore hardness of the base material which comprises a polishing pad differs, (A) is the base material by which the sheet member was arrange | positioned at the grid | lattice pattern, (B ) Shows a base material in which sheet members are arranged in a stripe pattern, and (C) shows a base material in which sheet members are arranged in a concentric pattern. 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) 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. In the urethane sheet 2, the thickness T1 is adjusted in the range of 200 to 2000 μm. The thickness of the urethane sheet 2 can be adjusted according to conditions during wet coagulation or buffing. 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 base material 8 is bonded to the back surface side of the urethane sheet 2 through the adhesive layer 7a on the one surface side. 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 includes two types of sheet members having plasticity and different Shore A hardnesses. Each of the two types of sheet members has a plurality of member pieces 8a and a plurality of member pieces 8b. That is, the Shore A hardness is different between the member piece 8a and the member piece 8b. A material having a Shore A hardness of 80 to 95 degrees is selected for the member piece 8a, and a material having a Shore A hardness of 5 to 40 degrees is selected for the member piece 8b. As a material of the member piece 8a, at least one selected from polyethylene terephthalate (hereinafter abbreviated as PET), polyethylene (PE), and polyvinyl chloride (PVC) can be used. On the other hand, as the material of the member piece 8b, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene terpolymer (EPDM), silicon rubber, fluorine Examples thereof include a soft rubber sheet formed from a resin or the like. Moreover, these soft rubber sheets can also be made into a foam by mixing a foam material. In this example, a PET flexible film having a Shore A hardness of 95 degrees is formed on the member piece 8a, and a silicon rubber flexible film having a Shore A hardness of 10 degrees smaller than the Shore A hardness of the member piece 8a is formed on the member piece 8b. Each is used. As shown in FIG. 2 (A), when viewed from the side of the substrate 8 that contacts the adhesive layer 7a, that is, the side that is bonded to the urethane sheet 2, the member pieces 8a and 8b have a lattice pattern. It is arranged to form. Further, the member pieces 8a and 8b have the same thickness and are arranged so as to be adjacent to each other in a planar shape. That is, as shown in FIG. 1, each of the member pieces 8a and 8b is in contact with the pressure-sensitive adhesive layer 7a on the one surface side and in contact with the pressure-sensitive adhesive layer 7b on the other surface side.

  The base material 8 has a thickness T2 in the range of 50 to 2000 μm. That is, the thickness of each of the member pieces 8a and 8b is the same as the thickness T2 of the base member 8, and the surfaces of the member pieces 8a and 8b that are in contact with the adhesive layer 7a form the same plane. The width Wb of the member piece 8b is adjusted to a range of 5 to 50 mm.

<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, the member pieces 8 a and 8 b are bonded in a lattice shape so as to be alternately adjacent to the other surface side of the pressure-sensitive adhesive layer 7 b covered with the release paper 9. 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. For the polyurethane resin, a polyester resin, a polyether resin, a polycarbonate resin, or the like is selected and used. For example, the polyurethane resin is dissolved in DMF so as to be 30% by weight. 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. When the DMF is removed from the polyurethane resin solution and the DMF and the coagulating liquid are replaced, the cell 5 of the nap layer 2b and the micropore (not shown) are formed in the polyurethane resin inside the skin layer 2a. A communication hole (not shown) that communicates the fine pores that are not formed 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 buffing is performed, buffing is performed on the side opposite to the skin layer 2a of the film-forming resin dried in the cleaning / drying process, that is, on the back side. 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 strip-like PET film having a thickness T2 and different lengths is prepared as the member piece 8a, and a rectangular silicon rubber film having a thickness T2 is prepared as the member piece 8b. In addition, an adhesive layer 7 b whose one side is covered with the release paper 9 is prepared. At this time, for example, a double-sided tape in which both surfaces of the pressure-sensitive adhesive layer 7b are covered with release paper may be used, and one release paper may be peeled off. The member pieces 8a and 8b are bonded to the other side of the exposed pressure-sensitive adhesive layer 7b so as to be alternately adjacent. The sizes of the plurality of member pieces 8a and 8b are adjusted in advance so that the member piece 8a and the member piece 8b do not overlap with each other and no gap is formed. In the obtained base material 8, the member pieces 8a and 8b having different Shore A hardnesses are arranged in a lattice pattern.

(Lamination)
After the urethane sheet 2 is cut into a disk-like desired size, the buffed surface (back surface) side of the urethane sheet 2 and the surface side opposite to the adhesive layer 7 b of the base material 8 are bonded together. 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. 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, the polishing pad 10 is completed by performing an inspection such as confirming that there is no adhesion of scratches, dirt, foreign matter, and the like.

  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 pressure (polishing pressure) is applied 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. In order to avoid such an unfavorable polishing action, groove processing or the like may be performed on the polishing surface side. The mobility and circulation of the abrasive particles AG are improved by the groove processing or the like, and it can be expected to improve the polishing rate and suppress the generation of scratches. However, when a slurry discharge path is formed by groove processing or the like, the pattern of the slurry discharge path is transferred to the processing surface S, and the quality of the processing surface S is degraded. 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 includes two types of sheet members having different Shore A hardnesses, and each sheet member has a plurality of member pieces 8a and a plurality of member pieces 8b. In the base material 8, the member pieces 8a and 8b are arrange | positioned so that it may adjoin alternately, and the urethane sheet 2 is bonded together planarly. Since the Shore A hardness differs between the member piece 8a and the member piece 8b, when a polishing pressure is applied, the pressing force applied to the abrasive particles supplied between the processed surface of the workpiece and the polishing surface P of the polishing pad 10 is increased. There will be a difference between the portion of the substrate 8 where the member piece 8a is disposed and the portion where the member piece 8b having a Shore A hardness smaller than the member piece 8a is disposed. That is, as shown in FIG. 3A, when a polishing pressure (arrow a) is applied, the pressing force applied to the abrasive particles AG at the position corresponding to the portion where the member piece 8b is disposed (in the urethane sheet 2 in the figure). Compared with the small arrow shown in FIG. 5), the pressing force (the large 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 member piece 8a is arranged becomes larger. For this reason, in the portion where the member piece 8a is disposed, 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 reliably exhibited. On the other hand, in the portion where the member piece 8b is disposed, the abrasive particles AG are easily pushed into the urethane sheet 2 side, and are easily moved in the direction along the polishing surface P while being sandwiched between the polishing surface P and the processing surface S. Become. 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 object to be polished 70 is equalized, and the circulation of the slurry is improved without performing groove processing or the like. The pressing of the abrasive particles AG can be reduced. Furthermore, since a pattern-like effect is obtained by the base material 8, groove processing or the like is not required on the polishing surface P, and thus pattern transfer to the object to be polished can be suppressed. As a result, the generation of scratches on the workpiece 70 can be suppressed, and the flatness within the processed surface S can be made uniform.

  In the present embodiment, the member pieces 8a and 8b are arranged in a lattice shape. For this reason, since the movement of the abrasive particles AG between the polishing pad 10 and the workpiece 70 is equalized, the flatness of the processed surface S can be improved. Moreover, the width Wb of the member piece 8b is adjusted to the range of 5-50 mm. For this reason, since the width | variety of the part which the abrasive particle AG tends to move is ensured, the planarity improvement of the to-be-polished object 70 can be aimed at. If the width Wb is less than 5 mm, it is difficult to ensure sufficient mobility of the abrasive particles AG. On the other hand, if the width Wb exceeds 50 mm, the width of the member piece 8a that exhibits a reliable polishing action is relatively small. Absent. Furthermore, in this embodiment, both the member pieces 8a and 8b have the same thickness, and one surface side is made to contact | abut to the adhesive layer 7a. For this reason, the urethane sheet 2 and the base material 8 can be bonded together while keeping the polishing surface P flat.

  Furthermore, in this embodiment, the thickness of the member pieces 8a and 8b, that is, 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 200 to 2000 μm. Even if a slight difference occurs in the thickness between the member piece 8a and the member piece 8b, the influence on the polishing process can be suppressed by the elasticity of the pressure-sensitive adhesive layer 7a, but if the difference in thickness increases, the substrate 8 This is not preferable because a difference in level is generated. Furthermore, when the thickness T2 of the base material 8 is smaller than 50 μm, it becomes difficult to sufficiently exert the Shore A hardness difference between the member piece 8a and the member piece 8b, and the above-described ease of movement of the abrasive particles AG is improved. You will lose. 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. Further, when the thickness T1 of the urethane sheet 2 is smaller than 200 μm, the size of the formed cell is limited by the thickness T1 even if the urethane sheet 2 is produced by the wet coagulation method, so that sufficient cushioning properties are exhibited during the polishing process. It becomes difficult. On the contrary, when the thickness T1 of the urethane sheet 2 is larger than 2000 μm, the polyurethane resin solution is not sufficiently solidified during the production by the wet coagulation method, and the formation of the foam structure and the formation of the urethane sheet itself may be insufficient. . 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, the example in which the member pieces 8a and 8b are arranged in a lattice pattern is shown as the base material 8. However, the present invention is not limited to this. The arrangement pattern of the member pieces 8a and 8b can be, for example, a stripe shape or a concentric circle shape instead of the lattice shape. That is, as shown in FIG. 2B, the strip-shaped member pieces 8a and 8b may be arranged in stripes. Further, as shown in FIG. 2C, the annular or circular member pieces 8a and 8b may be arranged concentrically. Furthermore, it can also be arranged in a checkerboard shape, a spiral shape, or a spot shape. Of course, the width Wb and the diameter may be adjusted in these cases. Thus, even if the arrangement pattern of the member pieces 8a and 8b is changed, the same effect as in the present embodiment can be obtained. In consideration of equalizing the movement of the abrasive particles AG, the member pieces 8a and 8b are preferably arranged so as to form a pattern having regularity. Furthermore, in the present embodiment, the disk-shaped polishing pad 10 has been exemplified, but the present invention is not limited to this, and it is needless to say that, for example, a rectangular shape may be used.

  Moreover, in this embodiment, after producing the urethane sheet 2 by the wet coagulation method, the base material 8 bonded with the adhesive layer 7b (including the release paper 9) and the urethane sheet 2 are bonded together. However, the present invention is not limited to this. For example, after the base material 8 is bonded to the surface side of the urethane sheet 2 subjected to the buff treatment via the adhesive layer 7a, the adhesive layer 7b is formed on the surface side opposite to the urethane sheet 2 of the base material 8. You may do it.

  Furthermore, in this embodiment, although the example which forms the base material 8 with two types of sheet | seat members each having the member pieces 8a and 8b was shown, this invention is not limited to this. Each sheet member forming the base material 8 may have different Shore hardness, and may be formed of three or more kinds of sheet members having different Shore hardness. Further, since the mobility of abrasive particles is improved by the difference in Shore hardness, each sheet member has a sheet member having a Shore A hardness in the range of 80 to 95 degrees and a Shore A hardness in the range of 5 to 40 degrees. If the sheet member is included, the same effect as that of the present embodiment can be obtained. In the present embodiment, the example in which the base material 8 also has a function of supporting the entire polishing pad 10 has been described. However, another support material may be bonded to the base material 8 in addition to 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 this embodiment, although the example which performed the buff process on the surface opposite to the skin layer 2a of the urethane sheet 2, ie, a back surface side, was shown, this invention is not limited to this. For example, depending on the type of the object 70 to be polished, etc., the buffing process may be performed on the skin layer 2a side instead of the buffing process on the back surface 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 which bonds the urethane sheet 2 and the base material 8 with an acrylic adhesive was shown, this invention is not restrict | limited to this. 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 (the same applies to the pressure-sensitive adhesive layer 7b), for example, a non-support tape that is a double-sided tape in which only the pressure-sensitive adhesive is sandwiched between two release sheets without having a supporting base material may be used. Is possible.

  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 the base material 8, a member piece 8a of a PET film (Shore A hardness 95 degrees) and a member piece 8b of a silicon rubber film (Shore A hardness 10 degrees) were arranged in a lattice shape. The member piece 8a was formed in a square shape having a side of 45 mm, and the member piece 8a having a width Wb of 5 mm was disposed so as to surround the member piece 8a. Further, the thickness T2 was set to 250 μm. A urethane pad 2 having a thickness T1 of 0.8 mm with an opening formed on the surface by buffing and a substrate 8 were bonded together to obtain a polishing pad 10.

(Comparative Example 1)
In Comparative Example 1, as a base material 18, a PET film having a thickness T2 of 250 μm and a groove having a width of 1 mm are formed on the polishing surface side of a urethane sheet 2 having a thickness T1 of 0.8 mm, and a square having a side of 49 mm. A polishing sheet 20 of Comparative Example 1 was obtained by pasting together a urethane sheet having a lattice groove pattern in which the shape portion was surrounded by grooves.

(Comparative Example 2)
In Comparative Example 2, a PET film having a thickness T2 of 250 μm and a urethane sheet 2 having a thickness T1 of 0.8 mm not subjected to grooving were bonded as the base material 18, and the polishing pad 20 of Comparative Example 2 was used. Obtained.

(Polishing performance evaluation)
Using the polishing pads of the examples and comparative examples, the aluminum substrate for hard disk was polished under the following polishing conditions, and the polishing performance was evaluated based on the polishing rate and waviness. The polishing rate is one of the numerical values indicating the polishing efficiency, and represents the polishing amount per minute by the thickness. It calculated from the grinding | polishing amount calculated | required from the weight reduction of the aluminum substrate before and behind grinding | polishing processing, the grinding | polishing area of an aluminum substrate, and specific gravity. Waviness is one of the measurement items for evaluating the surface accuracy (flatness) of objects to be polished such as disk substrates, silicon wafers, etc. per unit area observed with an optical non-contact surface roughness meter. The surface image waviness (Wa) is expressed in angstroms (Å). Evaluation was performed using a filter that transmits a wavelength of 80 to 500 μm with a Zygo New View 5022 as a test evaluation machine. When the numerical value of the measurement result is low, the undulation of the object to be polished is small, and the polishing surface is flatter. The measurement results of the polishing rate and waviness are shown in Table 1 below.
(Polishing conditions)
Polishing machine used: 9B-5P polishing machine, manufactured by Speed Fem Co., Ltd. Rotation speed: (Surface plate) 30 r / m
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 rates of the polishing pad 20 of Comparative Example 1 and the polishing pad 10 of Example 1 are 0.12 μm / min and 0.13 μm / min, respectively, and there is almost no difference. It was. However, in the numerical value of the undulation, the polishing pad 20 of the comparative example 1 showed 2.9 mm, whereas the polishing pad 10 of the example 1 showed 4.5 mm, and the improvement of the undulation was recognized. On the other hand, in the polishing pad 20 of Comparative Example 2 in which no groove is formed on the polishing surface side, the waviness is 3.0 mm, and the waviness is smaller and the flatness is higher than in the polishing pad 20 of Comparative Example 1 in which the groove is formed. However, since the circulating property of the abrasive particles AG was insufficient, the polishing rate was 0.08 μm / min, which was smaller than the polishing rates of Example 1 and Comparative Example 1. The polishing pad 10 of Example 1 has a polishing rate equivalent to that of the polishing pad 20 of Comparative Example 1 in which grooves are formed on the polishing surface, and the polishing pad of Comparative Example 2 in which no grooves are formed on the polishing surface. It has been clarified that a swell equivalent to 20 can be secured, and a decrease in flatness (occurrence of swell) due to groove formation can be suppressed.

  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 Member piece (part of sheet member)
8b Member piece (part of sheet member)
10 Polishing pad

Claims (4)

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 has at least two kinds of sheet members having plasticity and different Shore hardness, both of the sheet members have the same thickness, the sheet members of different Shore hardness are adjacent, and A polishing pad, wherein one surface side of the sheet member is disposed so as to be in contact with the pressure-sensitive adhesive layer.   The base material is characterized in that the sheet member includes a sheet member having a Shore A hardness in a range of 80 degrees to 95 degrees and a sheet member having a Shore A hardness in a range of 5 degrees to 40 degrees. The polishing pad according to claim 1.   3. The polishing pad according to claim 2, wherein the base material is uniformly arranged so that the sheet member forms a striped, latticed or concentric pattern.   The polishing pad according to claim 3, wherein the substrate has a thickness in a range of 50 μm to 2000 μm.

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