JP2971764B2 - Abrasive fixed type polishing table - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing platen used in a lapping apparatus for lapping a surface of a material to be polished.

[0002]

2. Description of the Related Art Materials to be polished, such as ceramics, glass, and quartz, constituting electronic parts and optical parts are generally required to have a surface smoothness and a reduced work-affected layer and a high surface accuracy. Lapping polishing is performed as a finishing process. This lapping polishing is performed, for example, on cast iron,
The workpiece is held immovable in the circumferential direction using a jig on the polishing surface of a disk-shaped polishing platen made of tin, copper, or the like, and is made of diamond, CBN (cubic boron nitride), or the like. While supplying the so-called superabrasive particles in which the free abrasive liquid or slurry is dispersed, the polishing plate is rotated to relatively move the workpiece in the circumferential direction, and the workpiece is placed on the polishing surface of the polishing table. It is performed by rotating.

[0003]

The above electronic parts and optical parts are often subjected to finishing (lapping polishing) because two or more kinds of different materials are often used in combination by bonding or the like. The material to be polished is often in a state in which such dissimilar materials are combined. For example, the magnetic head member 30 shown in FIG. 3 is one example. The magnetic head member 30 has a relatively high hardness A
Base 3 made of l ₂ O ₃ -TiC (Vickers hardness HV ≒ 2200)
Second, a laminated portion 38 in which an insulating layer 36 made of Al ₂ O ₃ (HV ≒ 990) having relatively low hardness and a magnetic layer 34 made of a magnetic material (HV ≒ 180) such as permalloy are stacked is formed by a CVD method or the like. And is fixed. When such a magnetic head member 30 is scanned over the recording magnetic body, the finished surface 40 to be subjected to lapping polishing is positioned on the magnetic body side. In addition, the distance between the magnetic layer 34 and the recording magnetic material is reduced as much as possible. In particular, this demand is strong in magnetic recording materials that have been increased in density in recent years. Therefore, in lapping, the base 3 it is necessary that two of the finished surface 40 _b does not cause processing step between the finished surface 40 _m of the insulating layer 36 and the magnetic layer 34.

However, when the lapping polishing is performed on the material to be polished using a combination of different materials as described above using loose abrasives, a material having a low hardness (in the above-described magnetic head member 30, the laminated portion 38) is removed relatively quickly. Therefore, a processing step d (d _a , d _m ) between the high-hardness base 32 and the low-hardness laminated portion 38 as shown in the drawing occurs. That is, the lapping polishing using the free abrasive grains has a problem that high surface smoothness of the whole polished material in which different materials are combined cannot be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain high surface smoothness even when lapping and polishing a material to be polished in which different materials are combined. It is an object of the present invention to provide a polishing platen that can perform polishing.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is to provide a polishing method in which the material to be polished is brought into sliding contact with the polishing surface when lapping the surface of the material to be polished. A disk, abrasive grains, and soft metal particles having an average particle diameter larger than the average particle diameter of the abrasive grains ,
Abrasive grains of 2 to 20 (vol%) and soft metal particles
An abrasive layer containing 30 to 70 (vol%) is provided on the surface layer on the polishing surface side.

[0007]

[Effect of the action and the Invention Thus, since the Lab MigakuJoban acts as a grinding wheel, lapping the object to be polished
A free abrasive liquid is not required for polishing, and even when lapping a workpiece to be polished in which dissimilar materials having different hardnesses are combined, the occurrence of processing steps due to the free abrasive grains is suitably suppressed. Moreover, soft metal particles having an average particle size larger than the average particle size of the abrasive particles are contained in the abrasive layer .
Ratio of soft metal particles 30 to 70 (vol%) to 20 (vol%)
Since it contains, the abrasive layer or et ratio comparatively large diameter of the abrasive grains
The area that retains the abrasive grains even if it falls off is the area of the polishing platen
Therefore, the loose abrasive grains are pressed by the material to be polished and embedded in the soft metal particles. Therefore, clogging hardly occurs, the polishing efficiency is stabilized, and the number of abrasive grains that can freely roll on the surface of the polishing platen is reduced, so that the generation of scratches on the surface of the polished material is suitably suppressed. . In addition,
If the amount of abrasive particles is too small, the polishing efficiency will decrease.
On the other hand, if there is too much, the dropped abrasive grains will become soft metal particles.
The likelihood of being retained is reduced, causing
You. Also, if the amount of soft metal particles is too small, the polishing platen
The total area of the soft metal particles relative to the area, that is, dropped
The area that holds the abrasive grains becomes small and causes scratches, etc.
If it is excessive, the strength of the abrasive layer will decrease, resulting in wear and deformation.
The shape becomes large, and the accuracy of the finished surface of the workpiece is obtained.
Absent.

[0008] Incidentally, various polishing plates provided with an abrasive layer have heretofore been proposed, but they are merely those obtained by binding abrasive particles with a binder such as resin in the same manner as a normal grindstone. Was. Therefore, when the abrasive grains are dropped or clogged by the abrasive powder, the polishing efficiency is reduced, and the dropped abrasive grains are interposed in a freely rolling state between the polishing platen and the workpiece. In addition, there is a problem that scratches occur on the surface of the material to be polished. Moreover, expensive superabrasives used for lapping polishing are different from general abrasives, and if the polishing efficiency is secured by the natural action of the abrasives, the waste of the abrasives increases and the processing cost increases. Therefore, there is also a problem that clogging is liable to occur due to the use of a binder having a high viscosity.

[0009] In the present application, the term "soft metal" means that free abrasive grains are easily embedded by plastic deformation. However, during lapping polishing, the retained abrasive grains are maintained and only involved in polishing. It has rigidity and, for example, tin, copper or the like is preferably used.

Preferably, the average particle size of the soft metal particles is several times or more, more preferably 10 times or more, the average particle size of the abrasive grains. In this case, the average particle size of the soft metal particles is sufficiently larger than the average particle size of the abrasive particles,
The rate at which the abrasive grains dropped from the abrasive layer are embedded in the soft metal particles is further increased, and the generation of scratches is further suppressed.

Preferably, the abrasive layer is formed by bonding the abrasive and the soft metal particles with a predetermined binder, and the ratio of the abrasive and the soft metal particles is preferably 2 to 20.
vol%, soft metal particles 30-70 vol%, binder 20-60
%, more preferably 5 to 15 vol.
%, Soft metal particles 40-60 vol%, binder 30-30 vol
% . When binding agent amount becomes too small to decrease the strength of the case soft metal particles are too much the same manner as the abrasive grain layer, the polishing efficiency is less abrasive appearing on the surface becomes excessively large drops.

Preferably, fine particles such as aluminum oxide or silicon oxide are mixed with the binder. With this configuration, the rigidity of the abrasive layer is further increased, edge dripping is prevented, and the accuracy of the finished surface of the polished material is further increased. The average particle size of the fine particles is preferably sufficiently smaller than the abrasive particles to fill the gap between the abrasive particles.For example, when the average particle size of the abrasive particles is about 1 μm, 0.1 μm It is preferred that the degree is about.

Preferably, the polishing platen is configured by providing the abrasive layer on a base plate made of metal, and the abrasive layer is formed by using a general abrasive as an abrasive. It is composed of a relatively thick reinforcing layer formed on the plate side and a relatively thin polishing layer formed on the surface side using superabrasive grains as abrasive grains. Generally, in the case of a superabrasive grindstone, the abrasive layer used for polishing or grinding is only a few mm in thickness at the most. It is desirable to make the grain layer relatively thin.
On the other hand, the base metal is generally made of a metal such as an aluminum alloy or stainless steel, and the abrasive layer is subjected to thermal stress due to the difference in the coefficient of thermal expansion and, at the same time, may receive an impact during handling. In order to provide the granular layer with strength sufficient to resist thermal stress and impact force, it is necessary to make the thickness relatively large. According to the above, even if the thickness of the polishing layer in which superabrasive grains are used is reduced, the thickness of the entire abrasive layer can be made sufficient by appropriately setting the thickness of the reinforcing layer. It is possible to obtain a polishing platen which is relatively inexpensive and has high strength. In addition, as the above-mentioned general abrasive grains, for example, aluminum oxide or silicon carbide is used, and in order to minimize the difference in the thermal expansion coefficient between the reinforcing layer and the polishing layer, the mixing ratio and the particle size are as follows. It is preferable to set the same as that of the superabrasive grains.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a view showing a cross section of a fixed abrasive platen (hereinafter referred to as a platen) 10 according to one embodiment of the present invention. The platen 10 has a disk shape having a size of, for example, about φ300 × t40 mm, and is made of, for example, an aluminum alloy having a thickness of about 30 mm and having high rigidity. It formed on an outer peripheral portion, a thickness of excluding for example part having a diameter of about 100mm in the central portion on one surface of and a abrasive grain layer 14 of approximately 10 mm. A screw hole 16 penetrating in the axial direction is provided at the center of the base plate 12.
The screw holes 16 are provided for attaching the surface plate 10 to a lapping polishing device (not shown).
The abrasive layer 14 is formed by sequentially laminating a reinforcing layer 18 and a polishing layer 20 from the base plate 12 side.

The reinforcing layer 18 has, for example, an average particle size of 1 μm.
m.sup.2 silicon carbide fine powder 21 and granular tin powder 24 having an average particle diameter of about 15 .mu.m are bonded by a binder 26 made of a thermosetting resin such as a phenol resin. Diamond abrasive grains 22 having an average particle size of about 1 μm and granular tin powder 24 having an average particle size of about 15 μm are similarly bound by a binder 26 made of a thermosetting resin such as a phenol resin. The thickness of the polishing layer 20 is relatively thin as compared with the reinforcing layer 18,
For example, it is about 2-3 mm. In addition, it is desirable that the particle size distribution of the granular tin powder 24 is selected so that the minimum particle size is sufficiently larger than the maximum particle size of the diamond abrasive particles 22, and in this embodiment, the average particle size is about It is determined to be 15 times. The degree of bonding of the abrasive grains is generally A to Z.
The softer the closer to A, the degree of bonding between the reinforcing layer 18 and the polishing layer 20 is about H to M, respectively.

FIG. 2 is an enlarged view of a part of the surface of the polishing layer 20 when the platen 10 is viewed from above in FIG. As described above, the polishing layer 20 is formed by combining the fine diamond abrasive grains 22 and the coarse grain tin powder 24 with the binder 2.
6, both are present in a state of being dispersed in the binder 26 on the surface thereof. In the present embodiment, the surface of the polishing layer 20 corresponds to the polished surface of the platen 10, and the surface layer on the polished surface side has diamond abrasive grains 22 and grains having a diameter larger than the maximum diameter of the diamond abrasive grains 22. An abrasive layer 14 containing granular tin powder 24 having a diameter (ie, soft metal particles) is provided. In the above-mentioned abrasive layer 14, the silicon carbide fine powder 21
And the diamond abrasive grains 22 are present at a relatively high density, but in the polishing layer 20, especially in the vicinity of the granular tin powder 24, the grains are localized so as to have a high density.
On the other hand, in the reinforcing layer 18, the silicon carbide fine powder 21 is not localized.

When lapping and polishing the workpiece 28 as shown in FIG.
0 is attached to the lapping polishing apparatus in the screw hole 16 and rotated about its axis, and while supplying a grinding liquid such as water to the surface of the polishing layer 20, that is, the polishing surface, the polishing target 2
8 against the polished surface with a predetermined pressing force.
Rotate around an axis parallel to the rotation axis of. Thereby, the lower surface of the material to be polished 28 is finished with high precision and smoothness by the polishing layer 20.

In this case, as described above, the surface plate 1
The polishing layer 20 including the diamond abrasive grains 22 and the granular tin powder 24 having a minimum particle diameter sufficiently larger than the maximum diameter of the diamond abrasive grains 22 is provided on the surface layer portion 0. Therefore, when performing lapping polishing, since the surface plate 10 acts as a grindstone, a free abrasive liquid is not necessary, and even when the polished material 28 is composed of a combination of different materials having different hardnesses, the free abrasive processing can be performed. The generation of the processing step caused by this is suitably suppressed. In addition, since the polishing layer 20 contains the granular tin powder 24 having a minimum particle diameter sufficiently larger than the maximum diameter of the diamond abrasive grains 22, the relatively large-diameter diamond abrasive grains 22 dropped from the polishing layer 20 are covered. Abrasive 28
To be embedded in the granular tin powder 24. Therefore, clogging hardly occurs, the polishing efficiency is stabilized, and the number of diamond abrasive grains 22 that can freely roll on the surface of the platen 10 is reduced. Is suppressed.

In addition, the average particle size of the granular tin powder 24 is sufficiently large, about 15 times the average particle size of the diamond abrasive particles 22, so that the diamond abrasive particles 22 dropped from the polishing The ratio of being embedded in the powder 24 is further increased, and the generation of scratches is further suppressed.

Further, the abrasive layer 14 has a relatively thick reinforcing layer 18 formed on the base plate 12 side by using silicon carbide fine powder 21 which is a general abrasive, and a surface layer formed by using diamond abrasive particles 22. And a relatively thin polishing layer 20 formed on the surface of the polishing layer 20 containing expensive superabrasive grains.
The thickness of the abrasive layer 14 is set to a thickness that can sufficiently withstand the thermal stress caused by the difference in the thermal expansion coefficient with the base metal 12 and the impact force given during the handling without making the thickness of the abrasive layer unnecessarily thick. be able to.

In general, in a super-abrasive grindstone or the like using super-abrasive grains such as diamond abrasive grains 22, if the grinding efficiency is ensured by utilizing the autogenous action of the abrasive grains 22 falling off, expensive abrasive grains are required. Because of the significant loss, the degree of bonding of the abrasive grains 22 is usually harder than R, so that they do not fall off easily. Therefore, in general, the superabrasive grindstone is easily clogged, and it is difficult to maintain the grinding efficiency. On the other hand, according to the present embodiment, although the degree of bonding is relatively low at about H to M, the abrasive grains 22 are likely to fall off.
Since the dropped abrasive grains 22 are embedded in the granular tin powder 24 and are involved in polishing, clogging hardly occurs, polishing efficiency is maintained, and loss of the abrasive grains 22 hardly occurs.

Next, a method of manufacturing the surface plate 10 configured as described above will be described below.

A raw material for a polishing layer and a raw material for a reinforcing layer having the composition shown in the upper and second rows of A to C in Table 1 below were prepared, and each of A to C was prepared. First,
A small amount of a wetting agent (for example, a petroleum organic solvent such as kerosene) was added to the raw material for the reinforcing layer, and the mixture was sufficiently mixed at a high speed with a powder mixer to prepare a clay for the reinforcing layer. Then, the raw material for the polishing layer was charged into a grinder in the order of tin powder, a wetting agent (as described above), diamond abrasive grains, and a phenol resin, and mixed to prepare a clay for the polishing layer. The granular tin powder used was a relatively coarse one having an average particle size of about 15 μm, and the diamond abrasive grains and silicon carbide fine powder used had an average particle size of about 1 μm.
In each case, novolak type phenol resin was finely pulverized to several μm and used.

[0025]

[Table 1]

Then, after filling the above-mentioned clay for the reinforcing layer into a predetermined mold and lightly pressing the same, the clay for the polishing layer is uniformly filled, and for example, a hot press in which a hot plate is previously heated to 190 ° C. It was set in an apparatus and subjected to hot compression molding so that the overall density was as shown in Table 1 above. In addition, the dimensions of the above-mentioned molds are all dimensions after molding, for example, φ301 × t10 ×
It was set to be φ99mm. Then, a part of the surface on the side of the reinforcing layer 18 was removed by cutting, and the surface plate 10 was obtained by adhering to the base plate 12 made of aluminum alloy with, for example, an epoxy resin. The reason for preparing the kneaded material for the polishing layer by the above procedure is to coat the tin powder with the diamond abrasive grains by adding the wetting agent to the tin powder and then adding the diamond abrasive grains. Thereby, as described above, the polishing layer 20 in which the diamond abrasive grains 22 are localized around the tin particles 24 is realized.

Using the surface plate 10 manufactured as described above, the magnetic head member 3 shown in FIG.
The result of finishing one surface of the sample No. 0 under the lapping polishing conditions shown below was compared with the process of loose abrasive processing. Table 1 shows the results of this example. The magnetic head member 30 is made of a combination of different materials having different hardnesses.
As shown in Table 1, according to the surface plates 10 of A to C of the present embodiment, the surface roughness and surface accuracy of the finished surface of the magnetic head member 30 (the material to be polished 28) are reduced by the conventional free abrasive processing. While maintaining the same level as above, the processing step could be reduced to about 1/2 to 1/3 of the conventional level. Specifically, in the loose abrasive processing, a processing step d _m between the base 32 and the magnetic layer 34 is performed.
There contrast was 20 to 30 nm, with the results under the platen 10, it was possible to reduce the machining step d _m of about 10 nm.

Moreover, according to the present embodiment, when obtaining the above-mentioned finished surface, the polishing rate (the processing amount per unit time) can be made about twice as large as the conventional one. The wear amount of the board 10 was about 1/2 of the conventional one. In addition, free abrasive grain processing, except that a slurry in which 1μm diamond abrasive grains were dispersed in water was used as a polishing liquid,
The polishing was performed under the same conditions as in the lapping polishing using the surface plate 10.

In Table 1, the composition D, E
Is a comparative example of this example. Comparative Example D was one in which the amount of abrasive grains and binder was too small and that of granular tin powder was too large, and Comparative Example E was that in which too much abrasive grains and binder and too little of the granular tin powder were mixed. Things. In the case of D, a high polishing efficiency cannot be obtained because the amount of the abrasive is too small, and the amount of the tin powder is too large and the amount of the binder is too small. Material to be polished 30
High accuracy of finished surface cannot be obtained. On the other hand, in the case of E, since the amount of the abrasive grains is too large and the amount of the tin powder is too small, the dropped abrasive grains are not sufficiently held by the tin powder, causing scratches and the like, and the amount of the binder is excessive. Therefore, the amount of abrasive grains appearing on the surface and acting on polishing is reduced, and the polishing efficiency cannot be obtained. Therefore, it is preferable that the abrasive layer 14 has a composition such as A to C in Table 1 above.

Next, a case where the present invention is used for simultaneous double-sided wrapping will be described. In this embodiment,
The abrasive layer 14, that is, the polishing layer 20 and the reinforcing layer 18 were prepared with the following composition. The manufacturing method of the platen 10 is substantially the same as that of the above-described embodiment, except that the preheating temperature of the hot plate of the hot press apparatus is about 180 ° C., and the overall density after the hot compression molding is 4.40 g / cm ^3. The molding size is φ332 × t10 × φ
158mm, the dimensions of the surface plate 10 are φ330 × t25 × φ160m
m. The base plate 12 is made of, for example, stainless steel.

The platen 10 was mounted on a double-sided lapping machine, and the upper and lower surfaces of the magnetic head member 30 were simultaneously polished. The lapping conditions were as shown below, and in this example, the polishing results were compared with those obtained by conventional free abrasive processing. As a result, while maintaining the surface roughness and surface accuracy (scratch, chip, chipping, etc.) at the same level as in the past, a polishing rate two to three times that of the conventional one was obtained, and the change with time was extremely small. Further, the wear amount of the surface plate 10 was comparable to that of a tin surface plate used for conventional loose abrasive processing. In addition, the lapping polishing conditions for loose abrasive processing are as follows:
Except that a slurry in which 3 μm diamond abrasive grains were dispersed in the polishing liquid was used, and the supply rate was 10 cc / min, the procedure was the same as in the case of using the platen 10.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other embodiments.

For example, in the embodiment, the abrasive layer 14 is composed of the reinforcing layer 18 and the polishing layer 20, and the silicon carbide fine powder (abrasive) 21 is used for the reinforcing layer 18 and the diamond abrasive 22 is used for the polishing layer 20. However, the type and particle size of the abrasive used are appropriately changed. For example, instead of diamond abrasive grains 22, C
BN abrasive grains may be used, and general abrasive grains such as aluminum oxide, silicon carbide, and cerium oxide may be used for the polishing layer 20. Further, the entire abrasive grain layer 14 may be composed of super abrasive grains such as diamond abrasive grains 22 and CBN abrasive grains, or general abrasive grains. That is, the abrasive layer 14 does not have to have a two-layer structure. However, when using superabrasive grains, it is preferable to use the superabrasive grains only in the polishing layer 20 as a two-layer structure in order to suppress an increase in processing cost.

As the soft metal particles contained in the abrasive layer 14, in addition to the granular tin powder 24 used in the embodiment, copper or a metal or alloy powder having the same properties as those is used. Is also good.

As the binder 26 made of a thermosetting resin used for the abrasive layer 14, a polyimide resin, a melamine resin, a polyester resin or the like is used in addition to the phenol resin and the epoxy resin shown in the embodiment. And finer than the diamond abrasive grains 22 and the silicon carbide fine powder 21 in the binder 26 (for example, an average particle diameter of 0.1 μm or less).
Aluminum oxide or silicon oxide may be mixed.

Further, in the embodiment, the case where the magnetic head member 30 in which different materials are combined is processed as the material to be polished 28 has been described.
Can be used for lapping polishing of various materials to be polished. Even in the case of the material to be polished 28 made of a single material in which a processing step cannot be formed, a high polishing rate can be obtained and the wear amount of the surface plate is small. can get.

Further, in the embodiment, the case where the present invention is applied to the disk-shaped surface plate 10 has been described, but the present invention can be applied to surface plates having various dimensions and shapes.

In the embodiment, the polished surface of the platen 10 is flat. However, as in a commonly used lapping platen, a concentric circle or a spiral is formed on the polished surface which is brought into sliding contact with the material to be polished. A groove having a predetermined depth may be provided.

Although not specifically exemplified, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a view showing a cross-sectional structure of a fixed abrasive grain polishing table according to one embodiment of the present invention.

FIG. 2 is an enlarged view of a part of the upper surface of the surface plate of FIG. 1;

3A and 3B are diagrams illustrating an example of a material to be polished to be wrapped, wherein FIG. 3A is a perspective view, and FIG.
It is a figure which expands and shows the principal part of -b cross section.

[Explanation of symbols]

 10: Abrasive grain fixed type polishing table 14: Abrasive grain layer 22: Diamond abrasive grains (abrasive grains) 24: Granular tin powder (soft metal particles) 28: Material to be polished

Continuation of the front page (56) References JP-A-3-234472 (JP, A) JP-A-6-226441 (JP, A) JP-A-8-41444 (JP, A) JP-A-64-2870 (JP) , A) JP-A-62-130179 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B24D 3/00 330 B24B 37/04 B24D 3/02 310 B24D 7/00

Claims (1)

(57) [Claims] 1. A polishing platen for lapping and polishing a surface of a material to be polished, wherein the material to be polished is brought into sliding contact with a polished surface, comprising: abrasive grains; Soft metal particles having a diameter of 2 to 20 (vol%)
An abrasive grain fixed type polishing table, wherein an abrasive layer containing the soft metal particles at a ratio of 30 to 70 (vol%) is provided on a surface layer portion on the polishing surface side.