JPS63185579A - Polishing tape - Google Patents

Abstract

PURPOSE:To prevent the formation of scratch flaws on a polished surface by using the polycrystalline diamond as polishing agent. CONSTITUTION:The polished surface (tape sliding surface) of a polished article 4 is finely polished by the hard particulate polishing agent 3 projecting from a polishing layer 2. In this case, polycrystalline diamond is used as the polishing agent 3, and since the shape of the polycrystalline diamond is thickset, formation of scratch flaws on the polished surface is prevented, and the polished surface call be finishing-polished finely.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polishing tape used for polishing magnetic heads, etc., and particularly to a polishing tape suitable for final polishing.

(Conventional technology) Chromium oxide, aluminum oxide,
Polishing tapes using silicon carbide or the like are known. This type of polishing tape has an abrasive agent with a hardness of 8.5.9.9.5 on the Mohs scale and has excellent polishing ability, so it is used for rough polishing and final polishing of video heads finished with a grindstone, for example. It is preferred to be used as

However, magnetic heads are integrally made of various materials (for example, ferrite and glass, sendust and glass), and because each material has a different hardness, the polishing ability of the abrasive in the polishing tape for each material differs. becomes. This may cause an adverse effect that uneven steps may be formed at the boundaries between the materials (hereinafter referred to as members).

As a countermeasure to this problem, there is a method of increasing the hardness of the abrasive to increase the difference in hardness between the abrasive and the object to be polished.

For example, this problem can be solved by using natural diamond as an abrasive, although it is somewhat expensive. However, this case has the disadvantage that the magnetic head may be damaged.

Therefore, there is a need for a polishing tape for final polishing that has good performance without forming any steps and is capable of precision polishing with almost no scratches on the surface to be polished.

(Object of the Invention) In view of the above circumstances, the present invention has been developed by uniformly polishing each member forming a magnetic head, so that there is no unevenness step at the boundary between each member, and the magnetic head surface has almost no unevenness. The object of the present invention is to provide a polishing tape for final polishing that allows precision polishing without any cost.

(Structure of the Invention) The polishing tape according to the present invention is characterized in that it contains polycrystalline diamond as an abrasive.

This polycrystalline diamond has fine crystallites that are tightly bound together, and has a stubby shape with no sharp edges throughout, making it difficult to scratch the polished object. Furthermore, since it has a Mohs hardness of 10, which is extremely hard, it can have a large difference in hardness from the object to be polished, and does not form uneven steps at the boundaries between various members forming the object to be polished, for example, a magnetic head.

In addition, the polishing tape mentioned here refers to tape-shaped ones as well as
This includes a wide range of disk-shaped objects.

(Implementation mode) Embodiments of the present invention will be described in detail below.

A polishing tape according to an embodiment of the present invention is composed of a flexible support 1 and a polishing layer 2 formed on the support 1, as shown in FIG. The polishing layer 2 is formed by mixing the polishing agent 3 and additives including a binder, a lubricant, and the like.

Such an abrasive tape polishes the abrasive layer 2 smoothly on the surface of an object to be polished, such as a magnetic head, using the hard particulate abrasive 3 protruding from the abrasive layer 2. It is something. An example of the polishing mode is shown in FIG. The illustrated case is for polishing the tape sliding surface of the magnetic head 4, and the polishing tape is moved at a constant speed from one reel (not shown) placed at two positions sandwiching the magnetic head 4 to the other. The abrasive 112 is caused to slide on the magnetic head 4 by running, and the hard particulate abrasive 3 protruding from the surface of the abrasive layer 2 polishes the tape sliding surface of the magnetic helad 4 shown in FIG.
(Surface to be polished) is polished smooth.

As the polishing agent 3, polycrystalline diamond is used. The size of this abrasive is effectively 3 microns or less for final polishing tapes, preferably 1 micron or less, and more preferably 0.5 to 0.01 microns. This polycrystalline diamond is synthesized by the explosive method, and has fine crystallites that have no fixed directionality and are tightly bound together, so it has the same strength in any direction. The particles have a stubby shape and are less likely to scratch the surface of the object to be polished.

The binder for binding the abrasive 3 is preferably one that is highly effective in dispersing the abrasive (for example, nitrocellulose, vinyl chloride resin, etc.) or one that has strong adhesion to the support (for example, polyester resin).

The abrasive must be sufficiently dispersed, and for molecular I1m, attritor, ball mill, sand grinder, etc. are suitable, but it is even better to use a kneader such as pressure kneader, open kneader, 13 rolls, etc. .

In addition to the binder, additives such as a lubricant, a dispersant, and an antistatic agent that improve the lubricity of the polishing layer 2 can be used as necessary.

In addition to the polycrystalline diamond used in the present invention, other abrasives may be included as the abrasive. They have a Mohs hardness of 6 or more, and chromium oxide, aluminum oxide, and silicon carbide are particularly preferred.

The mixing ratio of polycrystalline diamond in the total polishing agent is 3 by weight.
It can be used in a wide range from % to 100%. If the ratio is small, the grinding effect will be small. Furthermore, when cost is important, the amount of polycrystalline diamond used can be reduced as long as the characteristics requirements are satisfied.

The total amount of binder relative to 100 parts of abrasive is 5 to 200 parts, preferably 10 to 100 parts, particularly preferably 20 to 8 parts.
It is 0 copies. If it is smaller than this, the abrasive particles will easily come off, and if it is larger, the polishing ability will decrease.

As the above-mentioned flexible support 1, a non-magnetic support made of polyethylene terephthalate (PET), polyethylene-2,6-naphthalate or the like is preferably used.

The thickness of the polishing layer 2 may be determined appropriately depending on the shape, material, etc. of the object to be polished. For example, if the object to be polished is a magnetic head as shown in Fig. 2, if the thickness is too thick, the magnetic head will Since the contact between the polishing tape and the polishing tape becomes poor, the thickness is preferably 50 μm or less, preferably 1 to 10 μm, more preferably 2 to 5 μm.

In addition, in this polishing tape, it is preferable that the surface roughness Ra of polishing 12, that is, the center line average roughness, is 0.01 to 0.20, more preferably 0.03 to 0.15, and 00OS
~0.10 is more preferable for final polishing. R
If a is smaller than 0.01, the polishing ability will be insufficient,
This is because if it is larger than 0.20, scratches will easily occur. In addition, the above Ra is cut off (cut Off)
0.8 am, stylus radius 2 μm R1 stylus speed 0.
This value is based on the condition of 3m/Sec.

Next, a more detailed explanation will be given with reference to examples.

(Example 1) A coating solution with the following composition, which was dispersed for 8 hours using an attritor with a 1/4 inch diameter steel ball as the dispersion media and passed through a 1 μm filter, was spread on a 12 μm thick polyester film with a thickness of 4 μm. and then about 1
．． It was slit into 3CIR (1/2 inch) to make an abrasive tape. The heavy ω part is all solid content.

Coating Liquid Composition (Comparative Example 1) As a comparative example to the above example, an abrasive tape was prepared in the same manner as in Example 1 except that the abrasive was changed as shown below.

Natural single crystal diamond (size 0.25 micron,
Mohs hardness 10) ...30
0 parts (Comparative Example 2) As a comparative example to the above example, an abrasive tape was prepared in the same manner as in Example 1 except that the abrasive was changed as shown below.

Synthetic single crystal diamond (size 0.25 microns) Mohs hardness 10...300
Part (Comparative Example 3) As a comparative example to the above example, an abrasive tape was made in the same manner as in Example 1 except that the abrasive was changed as shown below.

CrzO3 (size 0.25 microns) Mohs hardness 8.
5...300 parts (Example 2) An abrasive tape was made in the same manner as in Example 1 except that the 1ill abrasive was changed as follows.

Cr2O3 (size 0.25 microns) Mohs hardness 8.
5...270 parts polycrystalline diamond (size 0.25 microns, Mohs hardness 10)
)...10 parts (Example 3) C was added to a paste prepared by kneading the following composition A in a pressure kneader for 1 hour, and the mixture was dispersed in an attritor for 8 hours.

A polishing tape was prepared in the same manner as in Example 1 except that a cloth solution having the following composition, which had been prepared by adding curing agent B and filtering through a 1 μm filter, was used.

Coating liquid composition Using each polishing tape, ferrite 5 as shown in Fig. 3 was applied.
A video magnetic head 4 having a surface made of glass 6 and
ferrite and glass boundary part 7 after polishing
The steps and surface scratches were investigated. In this polishing test, a magnetic head was roughly polished using a polishing tape containing aluminum oxide having a particle size of 8 μm as an abrasive, and then the magnetic head was polished with each of the above polishing tapes. Furthermore, the polishing layer surface roughness Ra of each of the above polishing tapes was examined under the conditions described above. The results are summarized in Table 1.

The polishing time was basically 5 seconds, but in Comparative Example 3, it was set to 60 seconds because the polishing ability was inferior. In Example 2, saturation was reached in 15 seconds, so the test was carried out in 15 seconds.

Table 1 In Table 1, the difference in level was evaluated as ON or OFF based on interference fringes at the boundary between ferrite and glass using an interference microscope. The number of scratches on the surface of the magnetic head is 2 μm in width, which was confirmed by looking at the surface of the magnetic head after polishing using a microscope.
The number of scratches is as follows (the number of scratches with an IW of 2 μm or more is 10.5 shoes).

From Table 1, it can be seen that the magnetic head surface scratches in Example 1 are superior to those in Comparative Examples 1 and 2. Further, in comparison with Example 1, Example 3 had enhanced dispersion, so it was found that Ra was small and the surface of the polishing layer was smooth, and surface scratches were further improved. Further, since the amount of diamond used in Example 2 is small, it is cheaper than Example 1.3 and Comparative Example 1.2, and is superior to Comparative Example 3 in terms of level difference.

(Effects of the Invention) The polishing tape according to the present invention has an abrasive layer containing polycrystalline diamond, which has a Mohs hardness of 10 and is harder than chromium oxide and aluminum oxide silicon carbide. As a result, there are no differences in level between the plurality of materials that make up the surface to be polished after grinding. In addition, its shape is stubby, with fine crystals tightly bound together, and it has the feature of not scratching the surface to be polished. Therefore, it can be suitably used as a polishing tape for final polishing to be used after rough polishing.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a sectional view of an embodiment of the abrasive tape according to the present invention, FIG. 2 is a diagram showing a mode of polishing a magnetic head using the abrasive tape shown in FIG. The figure is a partial front view showing the structure of the surface portion of the magnetic head near the head gap. 1... Flexible support 2... Polishing layer 3... Polishing agent 4... Magnetic head 5... Ferrite 6... Glass 7... Ferrite/glass boundary 8...・Head gap

Claims (1)

[Scope of Claims] 1) An abrasive tape comprising an abrasive layer containing an abrasive and a binder coated on a flexible support, wherein the abrasive contains polycrystalline diamond. . 2) The polishing tape according to claim 1, wherein the polishing layer has a surface roughness of 0.01 to 0.20.