US20100099343A1

US20100099343A1 - Polishing pad having abrasive grains and method for making the same

Info

Publication number: US20100099343A1
Application number: US12/493,491
Authority: US
Inventors: Chung-Chih Feng; I-Peng Yao; Yung-Chang Hung; Kun-Cheng Tsai; Chih-Yi Lin
Original assignee: BESTAC ADVANCED MATERIAL Co Ltd
Current assignee: BESTAC ADVANCED MATERIAL Co Ltd
Priority date: 2008-10-20
Filing date: 2009-06-29
Publication date: 2010-04-22
Also published as: TW201016391A

Abstract

The present invention relates to a polishing pad having abrasive grains and a method for making the same. The polishing pad having abrasive grains includes a plurality of fibers, a plurality of abrasive grains and a high polymer. The fibers intersect each other to form a fiber matrix. The abrasive grains are attached to the fibers. The high polymer covers the fibers and the abrasive grains. The abrasive grains will not easily scratch a surface of a workpiece to be polished due to the flexibility of the fibers.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a polishing pad and a method for making the same, in particular, to a polishing pad having abrasive grains and a method for making the same.
2. Description of the Related Art
In a conventional polishing method, a slurry is used together with a polishing pad. The slurry has a plurality of abrasive grains, which are used to polish a surface of a workpiece to be polished. The polishing pad has a plurality of pores, and the pores are communicated with each other, such that the slurry is uniformly dispersed over a surface of the polishing pad, so as to improve the polishing capability.
The conventional polishing method has the following disadvantages. During the polishing process, when the slurry flows through the pores, the abrasive grains of the slurry may easily block the pores, thus degrading the polishing capability. Then, a dresser needs to be used to dress the blocked pores and recover the polishing capability of the polishing pad. However, the addition of such a step in the original process will increase cost and lower efficiency.
In another conventional polishing method, a polishing pad having abrasive grains is used. FIG. 1 shows a schematic view of a conventional polishing pad having abrasive grains disclosed in Taiwan Patent Publication No. I233384. The polishing pad 1 having abrasive grains includes a bottom layer 11 and a polishing layer 12. The polishing layer 12 is disposed on the bottom layer 11, and has a resin 121 and a plurality of abrasive grains 122. The resin 121 covers the abrasive grains 122, and has a polishing surface 1211. A portion of the abrasive grains 122 is exposed to the polishing surface 1211 of the resin 121.
The conventional polishing pad 1 with abrasive grains has the following disadvantages. The polishing pad 1 having abrasive grains utilizes the resin 121 to fix the abrasive grains 122, so that during the polishing process, the abrasive grains 122 are fixed at the same position, abrade the workpiece to be polished with repetitive stress in a single direction, and thus easily scratch the workpiece to be polished. Meanwhile, as the resin 121 is gradually worn, the area of the abrasive grains 122 fixed within the resin 121 that are exposed to the polishing surface 1211 becomes larger, and the problem of scratching grows worse.
Therefore, it is necessary to provide a polishing pad having abrasive grains and a method for making the same, so as to solve the above problems.

SUMMARY OF THE INVENTION

The present invention is directed to a polishing pad having abrasive grains. The polishing pad comprises a plurality of fibers, a plurality of abrasive grains and a high polymer. The fibers intersect each other to form a fiber matrix. The abrasive grains are attached to the fibers. The high polymer covers the fibers and the abrasive grains.
The present invention is further directed to a method for making a polishing pad having abrasive grains. The method comprises the steps of: (a) providing a fiber matrix, in which the fiber matrix has a plurality of fibers and a plurality of abrasive grains, the fibers intersect each other, and the abrasive grains are attached to the fibers; (b) immersing the fiber matrix in a high-polymer solution; and (c) performing a curing step, such that the fiber matrix is covered with a high polymer.
Thereby, the abrasive grains may not easily scratch a surface of a workpiece to be polished due to the flexibility of the fibers, and the polishing pad has a desirable polishing capability due to the assistance of an acid or alkali slurry containing no abrasive grains or an electrolytic solution containing an electrolyte, thus avoiding the problem in the prior art that the abrasive grains of the slurry block the pores of the polishing pad. Moreover, after the polishing pad is used in the polishing process, only a small number of abrasive grains are left on the surface of the workpiece to be polished, which can be easily washed away by a simple rinsing procedure, and the wastewater may also be easily treated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a polishing pad having abrasive grains in the prior art;

FIG. 2 is a schematic view of a polishing pad having abrasive grains according to a first embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of fibers of the polishing pad having abrasive grains according to the first embodiment of the present invention, in which the fibers are solid;

FIG. 4 is a schematic cross-sectional view of fibers of the polishing pad having abrasive grains according to the first embodiment of the present invention, in which the fibers are hollow;

FIG. 5 is a flow chart of a method for making the polishing pad having abrasive grains according to the first embodiment of the present invention;

FIG. 6 is a schematic view of a polishing pad having abrasive grains according to a second embodiment of the present invention;

FIG. 7 is a schematic cross-sectional view of fibers of the polishing pad having abrasive grains according to the second embodiment of the present invention, in which the fibers are solid;

FIG. 8 is a schematic cross-sectional view of fibers of the polishing pad having abrasive grains according to the second embodiment of the present invention, in which the fibers are hollow; and

FIG. 9 is a flow chart of a method for making the polishing pad having abrasive grains according to the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 shows a schematic view of a polishing pad having abrasive grains according to a first embodiment of the present invention. The polishing pad 2 having abrasive grains comprises a plurality of fibers 21, a plurality of abrasive grains 22 and a high polymer 23. In other applications, the polishing pad 2 further comprises a bottom layer, which may be a glue layer or another composite layer.
The abrasive grains 22 are attached to the fibers 21, and the fibers 21 intersect each other to form a fiber matrix 24. In this embodiment, the fibers 21 are solid, and the abrasive grains 22 are disposed on surfaces of the fibers 21 (as shown in FIG. 3). In other applications, the fibers 21 may be hollow, and the abrasive grains 22 are disposed on surfaces of the fibers 21 (as shown in FIG. 4).
Preferably, the fibers 21 have a size of 0.001 to 6 denier. Preferably, the fibers 21 are made of a material selected from a group consisting of a polyamide resin, polyethylene terephthalate (PET), polyester resin, nylon, polypropylene (PP), acrylic resin and polyacrylonitrile resin. In this embodiment, the fiber matrix 24 is a non-woven fabric. Preferably, the fiber matrix 24 is formed by chemical bonding, thermal bonding, mechanical bonding, dry carding, direct web-forming or wet web-forming. In this embodiment, the abrasive grains 22 have an average diameter of 0.01 to 100 μm, and are made of a material selected from a group consisting of SiO₂CeO₂, Al₂O₃, oxides of transition metals and oxides of Group IIA metals.
The high polymer 23 covers the fibers 21 and the abrasive grains 22, and has a first surface 231 and a second surface 232. Preferably, a portion of the fibers 21 and a portion of the abrasive grains 22 are exposed to the first surface 231. The first surface 231 is a polishing surface. In other applications, the high polymer 23 completely covers the fibers 21 and the abrasive grains 22. After the polishing process has been performed for a period of time, and a portion of the high polymer 23 on the first surface 231 (polishing surface) is removed, a portion of the fibers 21 and a portion of the abrasive grains 22 are exposed to the first surface 231. Alternatively, a portion of the high polymer 23 on the first surface 231 is removed (for example, dressed or abraded) in advance before the polishing process is performed, such that a portion of the fibers 21 and a portion of the abrasive grains 22 are exposed to the first surface 231, and then the polishing process is performed. In this embodiment, the high polymer 23 is an intercommunicated porous high polymeric elastomer resin. Preferably, the high polymer 23 is made of a material selected from a group consisting of a polyamide resin, polycarbonate, polymethacrylic resin, epoxy resin, phenol resin, polyurethane resin, vinylbenzene resin and acrylic resin. In other applications, the second surface 232 of the high polymer 23 is disposed on the bottom layer.
FIG. 5 shows a flow chart of a method for making the polishing pad having abrasive grains according to the first embodiment of the present invention. Referring to FIGS. 2 and 5, first, in Step S51, a fiber raw material (not shown) is provided, and a spinning step is performed, such that the fiber raw material forms a plurality of fibers 21. Preferably, the spinning step is melt spinning, dry spinning or wet spinning. In this embodiment, the fibers 21 are solid (as shown in FIG. 3). In other applications, the fibers 21 may be hollow (as shown in FIG. 4). Preferably, the fibers 21 have a size of 0.001 to 6 denier. Preferably, the fibers 21 are made of a material selected from a group consisting of a polyamide resin, PET, polyester resin, nylon, PP, acrylic resin and polyacrylonitrile resin.
Next, in Step S52, a plurality of abrasive grains 22 is provided, and then attached to surfaces of the fibers 21 (as shown in FIGS. 3 and 4). In other applications, each of the abrasive grains 22 is exposed to the surfaces of the fibers 21; that is, each of the abrasive grains 22 is partially disposed inside the fibers 21 and partially exposed to the surfaces of the fibers 21. Alternatively, a portion of the abrasive grains 22 are disposed inside the fibers 21, and a portion of the abrasive grains 22 are exposed to the surfaces of the fibers 21 (as shown in FIGS. 7 and 8). Preferably, the abrasive grains 22 are made of a material selected from a group consisting of SiO₂CeO₂, Al₂O₃, oxides of transition metals and oxides of Group IIA metals.
Afterward, in Step S53, a drawing step is performed, such that the fibers 21 form a fiber matrix 24. In this embodiment, the fiber matrix 24 is a non-woven fabric. Preferably, the fiber matrix 24 is formed by chemical bonding, thermal bonding, mechanical bonding, dry carding, direct web-forming or wet web-forming. Then, in Step S54, the fiber matrix 24 is immersed in a high-polymer solution (not shown).
Finally, in Step S55, a curing step is performed, such that the fiber matrix 24 is covered with a high polymer 23. The high polymer 23 has a first surface 231 and a second surface 232. Preferably, a portion of the fibers 21 and a portion of the abrasive grains 22 are exposed to the first surface 231 of the high polymer 23. In other applications, in Step S55, the high polymer 23 completely covers the fiber matrix 24. Alternatively, in Step S55, the high polymer 23 completely covers the fiber matrix 24, and in Step S55, the method further comprises a step of removing (for example, dressing or abrading) a portion of the high polymer 23, such that a portion of the fibers 21 and a portion of the abrasive grains 22 are exposed to the first surface 231 of the high polymer 23. Preferably, after Step S55, the method further comprises a step of forming a bottom layer on the second surface 232 of the high polymer 23, in which the bottom layer is a glue layer.
FIG. 6 shows a schematic view of a polishing pad having abrasive grains according to a second embodiment of the present invention. The polishing pad 3 of this embodiment is substantially the same as the polishing pad 2 (FIG. 2) of the first embodiment. This embodiment is different from the first embodiment in that the abrasive grains 32 are disposed inside the fibers 31. In this embodiment, the fibers 31 are solid, the abrasive grains 32 are disposed inside the fibers 31, and a portion of the abrasive grains 32 are exposed to surfaces of the fibers 31 (as shown in FIG. 7). However, in other applications, the fibers 31 may be hollow (as shown in FIG. 8).
FIG. 9 shows a flow chart of a method for making the polishing pad having abrasive grains according to the second embodiment of the present invention. Referring to FIGS. 6 and 9, first, in Step S91, a fiber raw material (not shown) and a plurality of abrasive grains 32 are provided, and the abrasive grains 32 are added into the fiber raw material. Preferably, the abrasive grains 32 are made of a material selected from a group consisting of SiO₂CeO₂, Al₂O₃, oxides of transition metals and oxides of Group IIA metals.
Next, in Step S92, a spinning step is performed, such that the fiber raw material forms a plurality of fibers 31, in which a portion of the abrasive grains 32 are disposed inside the fibers 31, and a portion of the abrasive grains 32 are exposed to the surfaces of the fibers 31 (as shown in FIGS. 7 and 8). Preferably, the spinning step is melt spinning, dry spinning or wet spinning. In this embodiment, the fibers 31 are solid (as shown in FIG. 7). In other applications, the fibers 31 may be hollow (as shown in FIG. 8). Preferably, the fibers 31 have a size of 0.001 to 6 denier. Preferably, the fibers 31 are made of a material selected from a group consisting of a polyamide resin, PET, polyester resin, nylon, PP, acrylic resin and polyacrylonitrile resin.
Afterward, in Step S93, a drawing step is performed, such that the fibers 31 form a fiber matrix 34. In this embodiment, the fiber matrix 34 is a non-woven fabric. Preferably, the fiber matrix 34 is formed by chemical bonding, thermal bonding, mechanical bonding, dry carding, direct web-forming or wet web-forming. Then, in Step S94, the fiber matrix 34 is immersed in a high-polymer solution (not shown).
Finally, in Step S95, a curing step is performed, such that the fiber matrix 34 is covered with a high polymer 33. The high polymer 33 has a first surface 331 and a second surface 332. Preferably, a portion of the fibers 31 and a portion of the abrasive grains 32 are exposed to the first surface 331 of the high polymer 33. In other applications, in Step S95, the high polymer 33 completely covers the fiber matrix 34. Alternatively, in Step S95, the high polymer 33 completely covers the fiber matrix 34, and in Step S95, the method further comprises a step of removing (for example, dressing or abrading) a portion of the high polymer 33, such that a portion of the fibers 31 and a portion of the abrasive grains 32 are exposed to the first surface 331 of the high polymer 33. The first surface 331 is a polishing surface.
The present invention has the following advantages. During the polishing process, due to the flexibility of the fibers 21, 31, the fibers 21, 31 that are exposed to the first surface 231, 331 swing as the slurry flows under the effect of a stress between the polishing pad 2, 3 and the workpiece to be polished, such that the abrasive grains 22, 32 attached thereto also move accordingly instead of being fixed at the same position. Thereby, the abrasive grains 22, 32 may not easily scratch the surface of the workpiece to be polished. In addition, the polishing pad 2, 3 achieves a desirable polishing capability with the assistance of an acid or alkali slurry containing no abrasive grains or an electrolytic solution containing an electrolyte, thus avoiding the problem in the prior art that the abrasive grains of the slurry block the pores of the polishing pad. Moreover, after the polishing pad 2, 3 is used in the polishing process, only a small number of abrasive grains 22, 32 are left on the surface of the workpiece to be polished, which can be easily washed away by a simple rinsing procedure, and the wastewater may also be easily treated.
Examples are given below to illustrate the present invention, and the present invention is not limited thereto.

Example

The method of this example corresponds to that of the second embodiment. Referring to FIG. 6, first, a fiber raw material and a plurality of abrasive grains 32 are provided, and the abrasive grains 32 are added into the fiber raw material. The fiber raw material contains 57 wt % of PET and 40 wt % of polyethylene (PE), and the abrasive grains 32 are 3 wt % of SiO₂.
Next, a spinning step is performed, such that the fiber raw material forms a plurality of fibers 31. The fibers 31 are solid, a portion of the abrasive grains 32 are disposed inside the fibers 31, and a portion of the abrasive grains 32 are exposed to the surfaces of the fibers 31 (as shown in FIG. 7). The spinning step is melt spinning. In this step, the fiber raw material first passes through an extruder and is melted at 288° C., spun from a spinneret, and then cooled at 22° C. The spinning speed is 550 m/min. Afilament is obtained, which is then cut into short fibers to form the fibers 31.
Afterward, a drawing step is performed, such that the fibers 31 form a fiber matrix 34. The fiber matrix 34 is a non-woven fabric. Then, the fiber matrix 34 is immersed in a high-polymer solution (not shown). The high-polymer solution is made of a material selected from a group consisting of a polyamide resin, polycarbonate, polymethacrylic resin, epoxy resin, phenol resin, polyurethane resin, vinylbenzene resin and acrylic resin.
Finally, a curing step is performed. First, the fiber matrix 34 immersed in the high-polymer solution is placed in a 22% dimethylformamide (DMF) coagulation bath for coagulation, then placed in a rinsing bath to wash away the DMF, and dried at 150° C., so as to obtain a polishing pad 3 having the abrasive grains 32. Thereby, the fiber matrix 34 is covered with a high polymer 33. The high polymer 33 has a first surface 331 and a second surface 332. A portion of the fibers 31 and a portion of the abrasive grains 32 are exposed to the first surface 331 of the high polymer 33.
While several embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications which maintain the spirit and scope of the present invention are within the scope defined in the appended claims.

Claims

1. A polishing pad having abrasive grains, comprising:

a plurality of fibers, intersecting each other to form a fiber matrix;

a plurality of abrasive grains, attached to the fibers; and

a high polymer, covering the fibers and the abrasive grains.

2. The polishing pad according to claim 1, further comprising a bottom layer, wherein a second surface of the high polymer is disposed on the bottom layer.

3. The polishing pad according to claim 1, wherein the fiber matrix is a non-woven fabric.

4. The polishing pad according to claim 1, wherein the fibers are solid or hollow and the fibers are made of a material selected from a group consisting of a polyamide resin, polyethylene terephthalate (PET), polyester resin, nylon, polypropylene (PP), acrylic resin and polyacrylonitrile resin.

5. The polishing pad according to claim 1, wherein the abrasive grains are disposed inside the fibers, and a portion of the abrasive grains are exposed to surfaces of the fibers.

6. The polishing pad according to claim 1, wherein the abrasive grains are disposed on the surfaces of the fibers.

7. The polishing pad according to claim 1, wherein the abrasive grains are made of a material selected from a group consisting of SiO₂, CeO₂, Al₂O₃, oxides of transition metals and oxides of Group IIA metals.

8. The polishing pad according to claim 1, wherein the high polymer has a first surface and a second surface, and a portion of the fibers and a portion of the abrasive grains are exposed to the first surface.

9. The polishing pad according to claim 1, wherein the high polymer is made of a material selected from a group consisting of a polyamide resin, polycarbonate, polymethacrylic resin, epoxy resin, phenol resin, polyurethane resin, vinylbenzene resin and acrylic resin.

10. The polishing pad according to claim 1, wherein the high polymer is an intercommunicated porous high-polymeric elastomer resin.

11. A method for making a polishing pad having abrasive grains, comprising:

(a) providing a fiber matrix, wherein the fiber matrix has a plurality of fibers and a plurality of abrasive grains, the fibers intersect each other, and the abrasive grains are attached to the fibers;

(b) immersing the fiber matrix in a high-polymer solution; and

(c) performing a curing step, such that the fiber matrix is covered with a high polymer.

12. The method according to claim 11, wherein Step (a) comprises:

(a1) providing a fiber raw material, and performing a spinning step, such that the fiber raw material forms a plurality of fibers;

(a2) providing a plurality of abrasive grains, and attaching the abrasive grains to surfaces of the fibers; and

(a3) performing a drawing step, such that the fibers form the fiber matrix.

13. The method according to claim 12, wherein in Step (a1), the spinning step is melt spinning, dry spinning or wet spinning.

14. The method according to claim 11, wherein Step (a) comprises:

(a1) providing a fiber raw material and a plurality of abrasive grains, and adding the abrasive grains into the fiber raw material;

(a2) performing a spinning step, such that the fiber raw material forms a plurality of fibers, wherein a portion of the abrasive grains are disposed inside the fibers, and a portion of the abrasive grains are exposed to the surfaces of the fibers; and

(a3) performing a drawing step, such that the fibers form the fiber matrix.

15. The method according to claim 14, wherein in Step (a2), the spinning step is melt spinning, dry spinning or wet spinning.

16. The method according to claim 11, wherein in Step (a), the fibers are solid or hollow.

17. The method according to claim 11, wherein in Step (a), the abrasive grains are made of a material selected from a group consisting of SiO₂CeO₂, Al₂O₃, oxides of transition metals and oxides of Group IIA metals.

18. The method according to claim 11, wherein in Step (a), the fiber matrix is a non-woven fabric, and is formed by chemical bonding, thermal bonding, mechanical bonding, dry carding, direct web-forming or wet web-forming.

19. The method according to claim 11, wherein Step (c) further comprises a step of removing a portion of the high polymer, such that a portion of the fibers and a portion of the abrasive grains are exposed to a first surface of the high polymer.

20. The method according to claim 11, wherein after Step (c), the method further comprises a step of forming a bottom layer on a second surface of the high polymer.