JP2004322253A - Fixed abrasive grain polishing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed abrasive grain polishing material for allowing highly accurate polishing, and hardly sticking abrasive grains to a polishing object surface even after polishing. <P>SOLUTION: This fixed abrasive grain polishing material comprises a base material, and a polishing layer formed on a surface of the base material, and including the abrasive grain. The abrasive grains in the polishing layer includes substantially true-spherical oxide particles having low surface activity. The oxide particle having the low surface activity is small in affinity with the polishing object surface. Thus, the abrasive grain hardly sticks and remains on the polishing object surface even after the polishing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixed abrasive polishing material used for finish polishing of an end face of an optical fiber connector, a surface of a semiconductor wafer, or the like.
[0002]
[Prior art]
Optical fibers used as transmission means for optical communication are required to have as small an optical loss as possible with recent demands for large capacity and high efficiency. An optical fiber connector is used to connect the optical fibers. In the optical fiber connector, the periphery of the connection end of the optical fiber is covered with a ferrule. The quality of the connection end face of the optical fiber connector is very important because it affects the optical characteristics of the optical fiber. Therefore, the end face of the optical fiber connector is mirror-finished by polishing in a plurality of stages. As a final finish of polishing, precise mirror polishing is performed using a fixed abrasive polishing material such as a polishing sheet, a polishing tape, a polishing grindstone, a polishing cloth provided with a polishing layer containing fine abrasive grains. Precise mirror polishing using a fixed abrasive is being used as a final finish in polishing the surface and edge surface of a semiconductor wafer or the like.
[0003]
As a fixed abrasive polishing material used for precise mirror polishing, for example, a polishing medium in which a polishing layer containing abrasive grains and a predetermined binder is formed on a support is disclosed (for example, Patent Document 1). 1). Further, as a polishing tape provided with a polishing layer containing silica particles and a binder on a base material, a polishing tape having a center line average roughness of the polishing layer surface of 0.005 to 0.5 μm is disclosed. (For example, see Patent Document 2).
[0004]
[Patent Document 1]
JP 2002-254319 A [Patent Document 2]
JP-A-2002-254326
[Problems to be solved by the invention]
However, when precise mirror polishing is performed using a fixed abrasive polishing material as disclosed in Patent Literatures 1 and 2, after polishing, abrasives contained in the polishing layer adhere to the surface to be polished. There is a problem that remains. Therefore, it is necessary to separately provide a step of removing the deposits on the surface to be polished. Further, if the adhered substance remains on the surface to be polished, the desired optical characteristics cannot be obtained, and there is a possibility that a problem may occur during use.
[0006]
The present invention has been made in order to solve the above problems, and provides a fixed abrasive polishing material that can be polished with high precision, and in which abrasive grains and the like hardly adhere to a polished surface even after polishing. The task is to
[0007]
[Means for Solving the Problems]
The fixed abrasive polishing material of the present invention is a fixed abrasive polishing material comprising a base material and a polishing layer formed on the surface of the base material and containing abrasive grains, wherein the abrasive grains have low surface activity. It is characterized by containing substantially spherical oxide particles.
[0008]
That is, in the fixed abrasive polishing material of the present invention, the abrasive particles in the polishing layer contain substantially spherical oxide particles having low surface activity. Conventionally, oxide particles such as silicon dioxide (silica) and aluminum oxide (alumina) have been used as abrasive grains used for precision polishing such as mirror polishing. However, these oxide particles have a reactive group such as a hydrophilic group on the particle surface and have high surface activity. For this reason, for example, when the surface to be polished is made of a hydrophilic oxide, it is considered that the abrasive particles easily adhere to the surface to be polished due to its surface activity (affinity). The oxide particles contained in the abrasive grains of the fixed abrasive polishing material of the present invention have low surface activity. Therefore, the affinity for the surface to be polished is small, and it is difficult to adhere to the surface to be polished after polishing. Therefore, if the fixed abrasive polishing material of the present invention is used, the step of removing the deposit on the surface to be polished after polishing can be omitted, and the polishing step can be simplified. In addition, there is little possibility that the optical characteristics are deteriorated due to the remaining of the attached matter.
[0009]
The polishing characteristics of the fixed abrasive polishing material vary greatly depending on the shape of the particles constituting the abrasive grains. From the viewpoint of low surface activity, it is desired to use particles having a specific surface area as small as possible. Therefore, when there are few pores on the particle surface, it is desirable to use particles as spherical as possible. That is, the shape of the particles constituting the abrasive grains is an important element of the fixed abrasive polishing material. The oxide particles used in the fixed abrasive polishing material of the present invention are substantially spherical. The substantially spherical shape means a true sphere or a spherical shape very close to a true sphere. Specifically, it means spherical particles whose ratio of the minor axis to the observed major axis is 0.8 or more as a result of observation with a scanning electron microscope (SEM). Since the particle shape is substantially spherical, the cutting edge portion of the oxide particle is smooth and the contact area with the surface to be polished is small. Therefore, by using the fixed abrasive polishing material of the present invention, the roughness of the surface to be polished can be reduced, and the flatness of the surface to be polished can be improved.
[0010]
Furthermore, by using the same oxide as the conventional one as the abrasive grain, it is possible to obtain the same polishing performance, the quality of the surface to be polished, etc. as in the conventional polishing. Further, oxides such as silica are relatively inexpensive and easily available, which is advantageous in terms of cost. Further, the oxide particles have an advantage that they can be easily manufactured into a substantially spherical shape.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the fixed abrasive polishing material of the present invention will be described in detail. The fixed abrasive polishing material of the present invention is not limited to the following embodiment. The fixed abrasive polishing material of the present invention can be embodied in various forms with modifications, improvements, and the like that can be made by those skilled in the art without departing from the gist of the present invention.
[0012]
As described above, the fixed abrasive polishing material of the present invention includes a base material and a polishing layer formed on the surface of the base material and containing abrasive grains. The substrate may have any necessary elasticity and strength and can hold the polishing layer. For example, a film made of polyester such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), a film made of polycarbonate (PC), or the like is suitable. The thickness of the substrate is not particularly limited, and may be, for example, about 25 to 150 μm.
[0013]
Further, a buffer layer may be formed on the surface of the base material in advance according to the purpose, such as improvement in adhesion between the base material and the polishing layer and patterning of the surface of the polishing layer. For example, a buffer layer may be formed by forming an easily adhesive layer on the surface of the base material. Alternatively, the buffer layer may be formed by heat treatment, corona treatment, plasma treatment, or the like on the surface of the base material. The easy-adhesion layer can be formed by, for example, applying a buffer coating solution composed of an epoxy resin, an acrylic resin, a polyester resin, or the like to the surface of the base material and drying the coating solution.
[0014]
The polishing layer has abrasive grains having low surface activity and substantially spherical oxide particles. The following two can be mentioned as indices indicating the surface activity of the oxide particles contained in the abrasive grains. The first index is the sphericity of the oxide particles. The closer the oxide particles are to a true sphere, that is, the closer the sphericity is to 1, the lower the surface activity. Further, the closer the sphericity is to 1, the more difficult it is to scratch the surface to be polished. From the viewpoint of making the sphericity close to 1, the sphericity of the oxide particles is desirably 0.8 or more. It is more preferable that the sphericity is 0.9 or more. The sphericity of the oxide particles can be determined by observation with an SEM as described above.
[0015]
The second index is the particle size of the oxide particles. If the particle size is somewhat large, the surface activity of the particles will be low. From the viewpoint of optimizing the particle size, the average particle diameter of the oxide particles is desirably 0.01 μm or more and 10 μm or less. When the average particle diameter is less than 0.01 μm, the particle shape tends to be irregular when producing oxide particles, and it is difficult to obtain substantially spherical particles. Further, the adhesion of the oxide particles also increases. It is more preferable that the average particle size be 0.1 μm or more. On the other hand, if the average particle diameter exceeds 10 μm, the polishing action becomes large, and there is a possibility that the surface to be polished may be damaged such as causing a polishing scratch. Further, when the end face of the optical fiber connector is polished, a step may be generated between the optical fiber and the ferrule. It is more preferable that the average particle size be 1 μm or less. In this specification, a value obtained by a laser diffraction method is used as the average particle diameter.
[0016]
As described above, the abrasive grains in the fixed abrasive polishing material of the present invention have a sphericity of 0.8 or more, and an embodiment containing oxide particles having an average particle diameter of 0.01 μm or more and 10 μm or less is particularly preferable. .
[0017]
The type of the oxide constituting the oxide particles is not particularly limited. For example, silica (SiO ₂ ), silicon oxide (SiO), alumina (Al ₂ O ₃ ), titanium oxide (titania: TiO ₂ ), zirconium oxide (zirconia: ZrO ₂ ), chromium oxide (CrO ₂ ), and the like can be given. . In addition to the single metal oxide, a composite oxide such as SiO ₂ —Al ₂ O ₃ , SiO ₂ —TiO ₂ , and SiO ₂ —ZrO ₂ may be used. Above all, it is desirable to use silica because the polishing properties as the final finish are good.
[0018]
The method for producing substantially spherical oxide fine particles having a low surface activity is not particularly limited. For example, it can be manufactured by a method of oxidizing a metal powder such as a VMC (Vaporized Metal Combination) method. Further, it can be produced from at least one of a synthetic oxide and a natural oxide by a melting method. Here, examples of the synthetic oxide include colloidal silica, chloride hydrolyzed silica, and sol-gel method silica. Examples of the natural oxide include SiO ₂ , SiO, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , and CrO ₂ . In the above two methods, the metal powder, the synthetic oxide and the like as the raw materials are exposed to a high temperature, so that oxide particles having low surface activity can be obtained. The oxide particles obtained by the above two methods may be mixed and used.
[0019]
For example, according to the VMC method, substantially spherical oxide particles can be instantaneously obtained in large quantities. In the VMC method, a chemical flame is formed by a burner in an atmosphere containing oxygen, and metal powder for forming the target oxide particles is introduced into the chemical flame in such an amount that a dust cloud is formed. Is caused to synthesize oxide particles. For example, when obtaining SiO ₂ particles, Si powder may be introduced into a chemical flame. The particle size and the like of the particles to be produced can be adjusted by adjusting the particle size, the input amount, the flame temperature and the like of the powder to be charged.
[0020]
The abrasive grains may include other particles in addition to the oxide particles. For example, particles such as silica, silicon oxide, colloidal silica, organosilica, alumina, titania, zirconia, iron oxide, chromium oxide, and tin oxide that are commonly used as abrasive grains can be included. In this case, from the viewpoint of suppressing the attachment of the abrasive grains to the surface to be polished, the content ratio of the oxide particles in the abrasive grains is set to 3 wt% or more when the weight of the entire abrasive grains is 100 wt%. desirable. More preferably, the content is 10% by weight or more. Further, the abrasive grains may be composed only of the oxide particles. That is, the content ratio of the oxide particles may be 100 wt%. Some of the materials constituting the abrasive grains also serve as a binder described later. In the present specification, the weight of such a material is also included in the weight of the abrasive.
[0021]
The polishing layer contains, in addition to the above abrasive grains, abrasive grains and a binder for bonding the abrasive grains to the base material. The type of the binder is not particularly limited, and a known material may be used. For example, a urethane resin, a silicone resin, a vinyl chloride resin, an acrylic resin and the like can be mentioned. The mixing ratio of the binder in the polishing layer is not particularly limited, and for example, may be about 10 to 186 parts by weight based on 100 parts by weight of the abrasive grains. Further, the polishing layer may contain a lubricant, a dispersant for abrasive grains, and the like, in addition to the abrasive grains and the binder.
[0022]
The fixed abrasive polishing material of the present invention can be manufactured by applying a coating agent containing the above-mentioned abrasive particles, binder and the like to the surface of a substrate and drying. Specifically, first, a coating agent in which abrasive grains, a binder and the like are dispersed in a predetermined solvent is prepared. Next, a coating agent is applied to the surface of the base material by a bar coater method, a microgravure method, a comma coat method, or the like, and then heated to 20 to 140 ° C. and dried according to the coating agent. The thickness of the polishing layer to be formed may be appropriately set according to the material of the surface to be polished and the polishing process. For example, the thickness is preferably about 3 to 15 μm. The fixed abrasive polishing material of the present invention thus manufactured may be processed into a predetermined shape such as a sheet shape, a band shape, a circular shape, and used.
[0023]
The use of the fixed abrasive polishing material of the present invention is not particularly limited. The fixed abrasive polishing material of the present invention can be used, for example, for polishing various precision parts such as optical fiber connectors, semiconductor wafers, optical lenses, and optical disk substrates. In particular, when the surface to be polished is made of a hydrophilic oxide, polishing with the fixed abrasive polishing material of the present invention is more effective. Even when the surface to be polished is made of metal and a natural oxide film is formed on the surface of the surface to be polished by oxygen in the air, the polishing using the fixed abrasive polishing material of the present invention is effective. The fixed abrasive polishing material of the present invention can be used not only in the final finishing step of polishing but also in intermediate steps of polishing and the like.
[0024]
【Example】
The fixed abrasive material of the present invention was manufactured based on the above embodiment. In addition, as a comparative example, a fixed abrasive polishing material having low surface activity and substantially no spherical oxide particles was manufactured. Using the manufactured fixed abrasive polishing material, the end face of the ferrule of the optical fiber connector was finish-polished, and the polished surface after polishing was evaluated. Hereinafter, the production of the fixed abrasive, the final polishing, and the evaluation of the polished surface will be described.
[0025]
<Manufacture of fixed abrasives>
(1) As abrasive grains of # 11, colloidal silica (manufactured by Nissan Chemical Industries, Ltd .: average particle size 0.02 μm) and silica particles produced by the VMC method and having low surface activity (trade name “SE1050-WA”) Manufactured by Admatechs Co., Ltd .: average particle diameter 0.2 μm, sphericity 0.98). A silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a binder. First, 90 parts by weight of colloidal silica, 10 parts by weight of silica particles, and 100 parts by weight of a silicone resin were dispersed in methyl ethyl ketone (MEK) as a solvent to prepare a coating agent. The ratio of the silica particles in the abrasive grains was 10 wt%. Next, the prepared coating agent was applied to the surface of a polyester sheet (manufactured by Panac Co., Ltd .: 75 μm in thickness) as a base material by a bar coater method. In addition, the surface of the polyester sheet to which the coating agent was applied was previously subjected to an easy adhesion treatment. Then, it heated at 60 degreeC and dried the applied coating agent, and formed the polishing layer. The thickness of the formed polishing layer was 5 μm. The fixed abrasive abrasive thus manufactured was processed into a circular shape and subjected to the following finish polishing. In addition, this fixed abrasive polishing material was numbered as a polishing material of # 11. The present fixed abrasive polishing material is the fixed abrasive polishing material of the present invention.
[0026]
(2) Abrasive # 12 A fixed abrasive abrasive was prepared in the same manner as (1) except that the binder in the abrasive # 11 was changed to a polyurethane resin (manufactured by Asahi Denka Kogyo Co., Ltd.). Manufactured. The manufactured fixed abrasive abrasive was numbered as # 12 abrasive. The present fixed abrasive polishing material is the fixed abrasive polishing material of the present invention.
[0027]
(3) A fixed-grain abrasive was produced without using the silica particles having a low surface activity produced by the VMC method as the abrasive grains of # 21. That is, a fixed abrasive polishing material was produced in the same manner as in the above (1), except that only the colloidal silica was used in the production of the abrasive material of # 11. Incidentally, the mixing ratio of the colloidal silica and the silicone resin was 100 parts by weight: 100 parts by weight. The manufactured fixed-abrasive abrasive was numbered as # 21 abrasive. This fixed abrasive polishing material is a fixed abrasive polishing material of a comparative example.
[0028]
(4) Abrasive # 22 Similar to the abrasive # 21, a fixed abrasive abrasive was manufactured without using silica particles having a low surface activity manufactured by the VMC method as abrasive grains. A fixed abrasive polishing material was produced in the same manner as in (2) above, except that only the colloidal silica was used as the abrasive particles in the production of the abrasive material # 12. Incidentally, the mixing ratio of colloidal silica and polyurethane resin was 100 parts by weight: 100 parts by weight. The manufactured fixed abrasives were numbered as # 22 abrasives. This fixed abrasive polishing material is a fixed abrasive polishing material of a comparative example.
[0029]
<Evaluation of finish polishing and polished surface>
(1) Each of the abrasives # 11, # 12, # 21, and # 22 manufactured by finish polishing is attached to a polishing machine (“OFL-15”, manufactured by Seiko Instruments Inc.), and the ferrule end face of the optical fiber connector is attached. Finish polishing was performed for 180 seconds. For comparison, polishing sheets A and F (A: trade name “ATR-01”: manufactured by Nihon Micro Coating Co., Ltd., F: trade name “FOS-”) are commercially available for finish polishing of ferrule end faces of optical fiber connectors. 01 ": manufactured by Dai Nippon Printing Co., Ltd.). Note that a prescribed APC ferrule polishing prescription was applied to the ferrule end face of the optical fiber connector as pre-polishing until finish polishing. Then, the ferrule end face immediately after the finish polishing was evaluated by the following four items (a) to (d).
[0030]
(A) Presence or absence of attached matter on ferrule end face: The ferrule end face was observed with an optical microscope, and the presence or absence of attached matter was investigated. (B) Presence / absence of polishing flaw (scratch) on ferrule end face and mirror surface state: The ferrule end face was observed with an optical microscope, and the presence / absence of polishing flaw and the mirror surface state were examined. (C) Surface roughness (Ra) at the center line of the optical fiber: Ra (nm) was measured using a surface profile roughness measuring instrument manufactured by Taylor Hobson Co., Ltd. (D) The amount of protrusion of the optical fiber relative to the ferrule: The amount of protrusion (nm) of the optical fiber relative to the ferrule was measured using an ultra-precision level difference meter manufactured by Taylor Hobson.
[0031]
(2) Evaluation of surface to be polished (2-1) Polishing of abrasives # 11 and # 12 with abrasive # 11 and polishing with abrasive of # 12 have substantially the same ferrule end surface after polishing. It became. As an example of the ferrule end face after polishing, FIG. 1 shows an optical microscope photograph of the ferrule end face after finish polishing with the abrasive of # 11. As shown in FIG. 1, in the polishing with the abrasive material of # 11, no deposits and polishing debris were observed on the end surface of the ferrule which was the surface to be polished. Further, there was no polishing flaw on the end face of the ferrule, and the ferrule was finished in a good mirror surface state. The surface roughness (Ra) at the center line of the optical fiber portion was 2.0 to 2.6 nm. This is a value smaller by about 0.5 to 1.0 nm than the standard value. This indicates that the mirror surface condition of the polished surface is good. Also, the convex amount of the optical fiber with respect to the ferrule was 5 nm, and it could be confirmed that it was within the standard value range. The same result as above was obtained in the finish polishing using the abrasive of # 12.
[0032]
(2-2) Polishing of abrasive materials # 21 and # 22 With abrasive material # 21 and polishing with abrasive material of # 22, the ferrule end faces after polishing were almost in the same state. As an example of the ferrule end face after polishing, FIG. 2 shows an optical microscope photograph of the ferrule end face after finish polishing with the abrasive of # 21. As shown in FIG. 2, in the polishing with the abrasive of # 21, a raindrop-shaped deposit was observed on almost the entire end face of the ferrule. The size of the attached matter is about 1 to 150 mm, and it can be seen that the major axis directions are substantially aligned in the same direction. In addition, polishing dust was also observed on the peripheral edge of the ferrule end face. No polishing scratches were observed, and the mirror finished. The surface roughness (Ra) at the center line of the optical fiber and the convexity of the optical fiber with respect to the ferrule were both within the range of the standard value. The same result as above was obtained in the finish polishing using the abrasive of # 22.
[0033]
(2-3) Commercially available polishing sheets A and F
In the polishing using the polishing sheet A and the polishing using the polishing sheet B, the end face of the ferrule after polishing was almost in the same state. That is, in the polishing using the polishing sheets A and F, a raindrop-shaped deposit as shown in FIG. 2 was observed on the end face of the ferrule. In the polishing sheet A, the deposit was observed in about 70% of the entire end face of the ferrule. In the polishing sheet F, adhered matter was observed on almost the entire end face of the ferrule. The size of the attached matter was about 1 to 150 mm, and the major axis directions were almost aligned in the same direction. Even if the surface to be polished was rubbed with a nonwoven fabric or the like impregnated with alcohol, it was not possible to remove the deposits. From this, it can be seen that the deposit is fixed to the surface to be polished. In addition, polishing dust was also observed on the peripheral edge of the ferrule end face. No polishing scratches were observed, and the mirror finished. The surface roughness (Ra) at the center line of the optical fiber and the convexity of the optical fiber with respect to the ferrule were both within the range of the standard value.
[0034]
(2-4) Summary From the above, in the polishing by the abrasives of Comparative Examples # 21 and # 22 containing no oxide particles having low surface activity and the commercially available polishing sheets A and F, after polishing, the abrasive grains and the like were removed. It was found that the polishing debris adhered and remained on the surface to be polished. On the other hand, according to the abrasives # 11 and # 12, which are the fixed abrasive abrasives of the present invention, the ferrule end face of the optical fiber connector can be fixed without leaving abrasive grains or polishing debris on the surface to be polished. It was confirmed that polishing was possible with high precision.
[0035]
【The invention's effect】
The fixed abrasive polishing material of the present invention contains substantially spherical oxide particles having low surface activity in the abrasive grains in the polishing layer. Oxide particles contained in abrasive grains have low surface activity, and thus have low affinity with the surface to be polished. Therefore, after polishing, the abrasive grains hardly remain on the surface to be polished. Therefore, if the fixed abrasive polishing material of the present invention is used, the step of removing the deposit on the surface to be polished after polishing can be omitted, and the polishing step can be simplified. In addition, there is little possibility that the optical characteristics are deteriorated due to the remaining of the attached matter. Furthermore, since the shape of the oxide particles contained in the abrasive grains is substantially spherical, the roughness of the polished surface is reduced, and the flatness of the polished surface is improved.
[Brief description of the drawings]
FIG. 1 is an optical micrograph of an end face of a ferrule after finish polishing with an abrasive of # 11.
FIG. 2 is an optical microscope photograph of a ferrule end face after finish polishing with an abrasive of # 21.

Claims (5)

A substrate,
A polishing layer formed on the surface of the base material and containing abrasive grains,
A fixed abrasive polishing material comprising:
The abrasive is a fixed-abrasive abrasive having low spherical surface activity and substantially spherical oxide particles. The fixed abrasive polishing material according to claim 1, wherein the oxide particles have an average particle diameter of 0.01 μm or more and 10 μm or less. The fixed abrasive polishing material according to claim 1, wherein the sphericity of the oxide particles is 0.8 or more. 2. The fixed abrasive polishing material according to claim 1, wherein the oxide particles are produced by a method of oxidizing a metal powder or a melting method from at least one of a synthetic oxide and a natural oxide. 3. 2. The fixed abrasive polishing material according to claim 1, wherein the oxide particles are contained at a ratio of 3 wt% or more when the total weight of the abrasive particles is 100 wt%. 3.

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