JPH0584657A - Lapping surface plate and lapping liquid - Google Patents

Abstract

PURPOSE:To provide a lapping surface plate and lapping liquid, wherein a step difference of lapping between a substrate and a magnetic film generated when lapping a floating surface of a thin film magnetic head can be reduced, and to provide the thin film magnetic head of lapping its floating surface by using these lapping surface plate and lapping liquid. CONSTITUTION:Lapping is performed by using a surface plate manufactured of material concurrently having a phase of tin and a phase of brass with abrasive grain supporting rigidity larger than the tin and by using lapping liquid manufactured by mixing an anionic surface active agent 15 with an amphoteric surface active agent 16. In this way, a step difference of lapping of a thin film magnetic head can be reduced, and thus, a recording bit length of a magnetic disk can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head in which a processing step of a magnetic film portion which occurs when an air bearing surface is finished by lapping is smaller than that of a conventional thin film magnetic head. Not only the thin-film magnetic head but also a composite material made of any composite material that has a portion having different hardness, or has a portion whose surface is positively charged and a portion which is negatively charged in an aqueous solution. The present invention relates to a lapping plate, a lapping liquid, and a lapping method which are useful in polishing an abrasive.

[0002]

2. Description of the Related Art As discussed in Japanese Industrial Technology Center, Main points of magnetic head processing technology (1985), page 28, magnetic head polishing (lapping) has hitherto been performed with cast iron, tin and stone. , Kemets, etc. are used.
In particular, tin is generally used as a lapping plate for lapping the air bearing surface of a thin film magnetic head.

Also, Asakura Shoten, the basis of the interface phenomenon (197
3), as discussed on page 94,
An anionic surfactant (a sulfated product of a naphthalene condensate) was generally used to prepare a lapping solution in which a nonpolar powder such as diamond powder is dispersed.

[0004]

When the air bearing surface of the thin film magnetic head is finished by lapping using the above conventional lapping plate (in particular, tin), the substrate 13 of the thin film magnetic head and the protective film 1 are formed.
2. Since the hardnesses of the magnetic films 11 are different from each other, there is a problem that a processing step 22 as shown in FIG. 25 occurs on the air bearing surface.

The above-mentioned processing steps have different processing efficiencies when finishing different magnetic material surfaces constituting the magnetic head with the same lapping pressure, so that there is a difference in the depth at which the abrasive grains bite. Occur. For example, in a conventional thin film magnetic head made of a magnetic film having a Vickers hardness of about 200 kgf / mm and a protective film having the same hardness of 1300 kgf / mm or more, a substrate material, etc. Since the hardness difference is an issue, the maximum thickness of the magnetic film is 0.03μ.
A step of about m was generated.

When the air bearing surface of the thin film magnetic head is finished by lapping using the conventional lapping liquid, a protective film (generally made of alumina) 12 constituting the magnetic head or a magnetic film 11 and a substrate 13 are wrapped. It is known that an adsorption film of a surfactant in a liquid can be formed. (Whether or not the adsorption film can be formed depends on the type of electric charge on the surface of the magnetic film 1 and the type of surfactant (anionic). Yes, it is cationic, etc.))). As a result of a detailed study of the action of the adsorption film, the inventor of the present application has found that it is difficult to polish the portion where the adsorption film is present, which is one of the causes of the processing step 22 as shown in FIG. I found that. For example, as a lapping solution, 500 ml of a 1.0 wt% aqueous solution of Na alkyl diphenyl ether disulfonate has an average particle size of 0.25 μm.
When the diamond abrasive grain of m was lapped by dispersing 0.6 g, a step difference of about 0.03 μm was generated at the minimum.

If there is such a processing step, the flying height 20 of the thin film magnetic head cannot be substantially shortened by this amount, and the recording wavelength cannot be shortened. That is, there is a fixed relationship between the flying height 20 of the magnetic head and the recording wavelength. For example, in the example shown in FIG. 26, if the flying height increases by 0.01 μm, the bit length increases by 0.05 μm. Therefore, in the example shown in FIG. 26, if there is a processing step of 0.03 μm on the air bearing surface of the magnetic head, the bit length becomes 0.15 μm longer than when there is no step, and the recording density decreases accordingly. To do.

An object of the present invention is to provide a magnetic head capable of reducing the working step of the above-mentioned finished surface in the conventional thin film magnetic head and substantially shortening the flying distance, a manufacturing method thereof, and a magnetic disk device.

Another object of the present invention is to provide all composite materials having portions having different hardness, or having portions whose surface is positively charged and negatively charged in an aqueous solution. And a lapping plate, a lapping plate, and a polishing apparatus.

[0010]

The present invention has been made to achieve the above object.

Different materials having different hardnesses have different working efficiencies with the same lapping force. On the other hand, the lapping force and the processing efficiency are in a substantially proportional relationship. However, in a composite material composed of different materials, the lapping force is different between the different materials because the machining efficiency must be equal in the steady state. For this reason, there is a difference in the depth at which the abrasive grains penetrate into the material to be polished, resulting in a processing step. When a material having a larger abrasive grain supporting rigidity than tin, which has been used as a conventional lapping plate, is selected as the lapping plate and lapping is performed using these materials, the difference in the depth at which the abrasive grains are difficult to be abraded becomes small, As a result, the processing step becomes smaller than the conventional one.

However, lapping with a material having a higher abrasive grain supporting rigidity than that of tin increases the surface roughness. Therefore, by lapping a material having both a material phase having a large abrasive grain supporting rigidity and a tin phase as a lapping plate, the lapping has the same surface roughness as the lapping with tin, and the tin lapping is performed. The processing step is smaller than lapping.

Further, an anionic surfactant is used in the conventional lapping solution, and an adsorbed film is formed on the material constituting the composite material whose surface is positively charged, but the surface is negative. Since an adsorption film is not formed on a material that is charged to a high level, the difference in the lapping force that acts on the abrasive grains between different materials is large, and the processing step is large. However, the wrap liquid made by mixing the anionic surfactant and the amphoteric surfactant forms an adsorption film not only in the positively charged part of the composite material but also in the negatively charged part. The difference in the lapping force acting on the abrasive grains between different kinds of materials becomes small, and the processing step becomes smaller than that in the conventional lapping.

[0014]

When the composite material is lapped, a difference occurs in the lapping force acting on the abrasive grains lapping different kinds of materials, which causes a difference in the vertical movement amount of the abrasive grains, resulting in a machining step on the lap surface of the composite material. Occurs. Therefore, by using a material having a high rigidity for supporting the abrasive grains in the lapping plate and lapping the lapping plate with the lapping plate, the difference in the vertical movement amount of the abrasive grains is reduced and the processing step is reduced.

Further, by lapping the tin phase and the phase of a material having a high abrasive grain supporting rigidity together, it is possible to obtain a surface roughness equivalent to that of tin lapping, and The processing step can be made smaller than that of lapping with tin.

Further, an anionic surfactant is used in the conventional lapping liquid, and an adsorbed film is formed on the material constituting the composite material whose surface is positively charged, but the surface is negative. Since an adsorption film is not formed on a material that is charged to a high level, the difference in the lapping force that acts on the abrasive grains between different materials is large, and the processing step is large. However, the lapping liquid made by mixing anionic surfactant and amphoteric surfactant forms an adsorption film on all surfaces of the composite material, so the difference in lapping force acting on the abrasive grains between different materials is small. Therefore, the processing step becomes smaller than the conventional lapping solution.

When lapping is performed using the lapping plate and / or the lapping liquid, a magnetic head having a small working level difference can be obtained. Moreover, if the magnetic head is used,
A magnetic recording device having a higher recording density than the conventional one can be obtained.

[0018]

EXAMPLES Before starting the description of the examples, the basic matters of the present invention will be described.

In lapping a composite material, that is, a material composed of different materials having different hardnesses, a constant lapping force acts on the abrasive grains, so that the lapping efficiency is different for each constituent material. On the other hand, the lapping force and the lapping efficiency are almost proportional.

[0020]

[Formula 1] ΔV ₁ / Δt = α ₁ · P ₁

[0021]

[Formula 2] ΔV ₂ / Δt = α ₂ · P _{2 In} Formula ₁ and Formula 2, ΔV ₁ (mm ³ ), ΔV
₂ (mm ³ ) is the amount of dissimilar materials that are lapped for a fixed time Δt (s). P ₁ (N) and P ₂ (N) are
It is the lapping force that acts on the abrasive grains involved in the lapping of different materials. α ₁ and α ₂ are material constants indicating the easiness of material scraping. However, α ₁ ≠ α ₂ .

By the way, when a machining step having a certain size is formed in each different material, the lapping efficiency becomes equal between the different materials, so that a difference in the lapping force occurs between the different materials so as to conform to this. .. That is, the relationships shown in the following Expressions 3 and 4 are established in Expressions 1 and 2.

[0023]

[Formula 3] ΔV ₁ / Δt = ΔV ₂ / Δt That is,

[0024]

## EQU4 ## α ₁ .P ₁ = α ₂ .P _{2 In} this case, since α ₁ ≠ α ₂ , P ₁ ≠ P ₂ .

This difference in the lapping force causes a difference in the vertical movement amount of the abrasive grains during lapping based on the rigidity with which the lapping plate supports the abrasive grains (abrasive grain supporting rigidity), which is processed on the lap surface of the composite material. It causes a step. The term "supporting rigidity" as used herein means how the amount of plastic deformation that occurs when a certain load is applied to a material changes depending on the magnitude of the load.

The above description will be more specifically described with reference to FIGS. 1 and 2 regarding the lapping of the thin film magnetic head. The substrate 13 has a Vickers hardness of Hv≈1300, but the protective film 12 has Hv≈1000 and the magnetic film 11 has Hv≈200, and the magnetic film 11 is smaller than the substrate by an order of magnitude. The force acting on the abrasive grains is small in a soft place and large in a hard place. This is the above equation 4, and the material constant of the soft material is α
_This is because when the material constant of a hard material is α ₂ , α ₁ > α ₂ and P ₁ <P ₂ . When the force is small, the abrasive grains are shallowly pushed into the lapping plate, and when the force is large, the abrasive grains are deeply pushed. That is, depending on the hardness of the material to be lapped, the pressing amount of the abrasive grains into the lapping platen is different, and there is a processing step.Therefore, the rigidity with which the lapping platen supports the abrasive grains, that is, the abrasive grain supporting rigidity is By lapping with a large lapping plate, the difference in the vertical movement amount of the abrasive grains due to the difference in the lapping force acting on the abrasive grains becomes small, and the processing step can be reduced.

In order to investigate the rigidity of the lapping plate for supporting the abrasive grains, an experiment was carried out in which a diamond indenter was pressed into the lapping plate material. Diamond indenter means abrasive grain. The experimental apparatus is shown in FIG. The voice coil 32 in FIG. 3 applies a load to the indenter, and the displacement of the indenter pushed in is detected by the differential transformer 33 in FIG. Tin, which has been conventionally used as a lapping plate material, and aluminum, which is a soft metal that can be used as a lapping plate material (JIS A10
50P), copper (JIS C1020P), brass (with a mass of copper of 50% or more), the experimental results of pushing the indenter in a depth of 0.02-0.7 μm are shown in FIG. 7 shows. Very slow loading speed (0.0
The depth when pressed at 24 mN / s) is Z _0, and the ratio of the pressed depth Z to this is shown on the vertical axis. The indentation depth decreases as the loading speed increases. This is a phenomenon known as strain rate dependence of plastic deformation, and it can be further seen that the amount of decrease in the indentation depth varies depending on the load.

From the results of this experiment, head wrapping conditions (lap speed of about 0.5 m / s, average lap pressure of about 0.
At 8 mN / mm ² , the load speed per abrasive grain is about 1.3 mN / s and the load is around 0.1 mN).
It can be seen that tin has a large change in the amount of indentation with respect to the change in load, that is, it has a low abrasive grain supporting rigidity and is likely to cause a processing step. On the other hand, aluminum, copper, and brass are more
The change in pushing amount with respect to the change in load is small, that is,
It can be seen that the material has a large abrasive grain supporting rigidity and is less likely to cause a processing step.

FIG. 8 shows the size of the processing step when lapping is performed using a lapping plate made of these materials.
As lapping conditions, a diamond abrasive grain having a lapping speed of 0.5 m / s, an average lapping pressure of 0.8 mN / mm ² , and an average particle diameter of 0.25 μm was used. Compared to tin, aluminum, copper,
Lapping with a brass lapping plate reduces the machining step. As a result, the bit length of the magnetic disk can be shortened, and the recording density can be improved accordingly.

However, the Vickers hardness of aluminum is Hv≈50, and the Vickers hardness of copper and brass is Hv.
≈100, which is harder than tin (Hv≈15). Therefore, when using a lap plate of aluminum, copper, brass, if some of the abrasive grains have a large grain size,
The large abrasive grains form scratches on the lap surface and increase the surface roughness. FIG. 9 shows the results of the surface roughness of the air bearing surface of the head lapped under the above lapping conditions. The surface roughness lapped with aluminum, copper and brass is larger than that lapped with tin. this is,
This is because the abrasive grains having the average grain size of 0.25 μm and the maximum grain size of 2 μm are actually mixed.

If the surface roughness of the air bearing surface is large, the flying characteristics of the magnetic head become unstable, which hinders the improvement of recording density.

From the above, a material having both a portion having a small hardness such as tin and a portion having a hardness larger than that of tin and having a larger abrasive grain supporting rigidity (that is, copper and brass in this example) is combined. By lapping, the surface roughness is smaller than lapping with a lapping plate made only of aluminum, copper, and brass, and the working surface is smaller than lapping with a lapping plate because it is made of tin only Should be obtained.

Therefore, in this embodiment, the head air bearing surface was lapped by the following two types of lapping platens.

First, tin powder and brass powder (containing 50% or more by mass of copper) powder are used, in mass%, from 30% tin 70% brass to 80% tin 20% brass. After uniformly mixing in the range, near the melting temperature of tin (180 ℃ or more 21
It is a product obtained by applying pressure at 0 ° C. or lower) and sintering. FIG. 10 shows a structural chart of this observed under a microscope. In the sintered material of the tin powder and the brass powder, the Vickers hardness of the tin phase 2 is Hv≈20, and that of the brass phase 1 is Hv≈200.

Second, 450 ° C. or higher and 500 ° C.
In the following environment, molten copper is mixed with molten copper at a ratio of 0.7% to 7.6% by mass with respect to tin, and then cooled. FIG. 11 shows a structure chart of this observed under a microscope. The Vickers hardness of the tin phase 3 is Hv≈20, and the phase 4 of the compound of copper and tin is Hv≈200.

FIGS. 12 and 13 show the processing step and the maximum height (Rmax) of the head air bearing surface when the head air bearing surface is lapped by a lapping plate using these materials.
As can be seen from this figure, a sintered material of tin powder and brass powder, and a casting of tin and copper were used as a lapping plate,
By lapping the head air bearing surface, it was possible to obtain a head air bearing surface having a smaller processing step than the conventional tin lapping and having a surface roughness equivalent to that of the conventional tin lapping.

As a method of reducing the processing step, in addition to the above-described method, the material constant α ₁ between different materials
A possible method is to reduce the difference between α ₂ and α ₂ . This is α ₁
Power P ₁ and P acting on the abrasive grain by reducing the difference between alpha ₂ and
The difference between ₂ is made small, and as a result, the difference in the amount of vertical movement of the abrasive grains is made small. A method of reducing the difference between α ₁ and α ₂ by the action of the lapping solution will be described below.

Generally, the surfaces of metals, oxides, and ionic crystal materials have a charge in an aqueous solution, but
₂ O ₃ ) has no charge on the surface in a weak alkaline aqueous solution having a pH of about 9, and has a positive charge on the acidic side and a negative charge on the alkaline side of the pH.

By the way, in general, the material forming the magnetic head shown in FIG. 1 is metal for the magnetic film 11 and alumina for the protective film 12. The substrate 13 is a ceramic made of an ionic crystal partially containing alumina, or a ceramic other than that.

A magnetic head made of such a material has p
When lapping the air bearing surface of the magnetic head with a lapping liquid of H9 or less, the surfaces of the magnetic film 11 and the substrate 13 are negatively charged, and the protective film 12 is positively charged.

Conventionally, in order to disperse nonpolar diamond abrasive grains in a water-soluble lapping solution, a sulfated product of a naphthalene condensate, that is, an anionic surfactant has been dissolved in a polishing solution as a dispersant. When lapping is performed using this lapping liquid, as shown in FIG. 14, the anions of the anionic surfactant and the positive charges on the surface of the protective film 12 attract each other, and the lapping liquid does not contribute to the dispersion of the abrasive grains. It is known that the remaining anionic surfactant is adsorbed only on the surface of the protective film 12).

The inventor of the present invention has studied the influence of the adsorbed film from various angles, and has found that the presence of such adsorbed film affects the lapping. That is, the protective film 12 is less likely to be lapped because the abrasive grains are less likely to be caught by the adsorption film of the anionic surfactant. On the other hand, the magnetic film 11 without the adsorption film and the substrate 13
Since such an adsorption film does not exist, the abrasive grains do not easily get caught, and the lapping does not become difficult. Therefore, the step 24 between the protective film 12 and the substrate 13 (hereinafter referred to as “protective film step”) 24 is small, and the step between the magnetic film 11 and the protective film 12 (hereinafter referred to as “magnetic film step”) 23 is large. Become.

On the contrary, when a cationic surfactant is used as a dispersant for the abrasive grains, an adsorption film of the cationic surfactant is formed on the surface of the magnetic film 11 and the substrate 13, as shown in FIG. This adsorption film cannot be formed on the protective film 12. for that reason,
It has been found that the step 23 between the magnetic film 11 and the protective film 12 is small, and the step 24 between the protective film 12 and the substrate 13 is large.

FIG. 16 shows the result of lapping using a lapping solution containing such a dispersant. The processing steps shown in the figure are the steps of the protective film portion step 24 and the magnetic film portion step 23.
Is equivalent to the sum of and. The lapping conditions were a lapping speed of 0.5 m / s, an average lapping pressure of 0.8 mN / mm ² , and a lapping plate made of tin. Further, as a lapping solution using an anionic surfactant, Na-alkyl diphenyl disulfonate, that is, an average particle size of 0.2 in 500 ml of a 1.0 wt% aqueous solution of an anionic surfactant.
A dispersion of 0.6 g of 5 μm diamond abrasive grains was used. As a wrap liquid using a cationic surfactant, alkyl tri-methyl ammonium chloride, that is, a 1.0 wt% aqueous solution of a cationic surfactant 50
0 ml of diamond abrasive grains having an average particle size of 0.25 μm.
A dispersion of 6 g was used.

From the above results, the inventors of the present invention have found that the magnetic film 1
1. If an adsorption film is formed on any one of the protective film 12, the protective film 12, and the substrate 13, the difference between the material constants α ₁ and α ₂ will be small, and as a result, the processing step will be small. Came to do.

As the surfactant, there is an amphoteric surfactant having both a positively biased portion and a negatively biased portion in one molecule. By using this, the magnetic film 11 and the protective film 12 are used. An adsorption film can be formed on all of the substrate 13. However, since the amphoteric surfactant has a smaller absolute value of electric charge than the anionic surfactant, the dispersibility of the abrasive grains is poor.

Further, it is not possible to form an adsorption film with the anionic surfactant on the protective film 12 and simultaneously form an adsorption film with the cationic surfactant on the magnetic film 11 and the substrate 13. This is because the anion part of the anionic surfactant and the cation part of the cationic surfactant cause a chemical reaction and precipitate, so that they no longer have the dispersibility as a surfactant. In this example, the abrasive grains were dispersed in pure water in which an anionic surfactant and an amphoteric surfactant were mixed, and this was used as a lapping liquid. The anionic surfactant and the amphoteric surfactant do not react with each other even when mixed to cause precipitation.

When such a lapping solution is used, FIG.
As shown in, the anionic portion of the anionic surfactant and the negatively charged portion of the amphoteric surfactant are adsorbed on the surface of the protective film 12 that is positively charged. At the same time, the positively charged portion of the amphoteric surfactant is adsorbed on the surface of the magnetic film 11 and the surface of the substrate 13 which are negatively charged. The results of wrapping with the lapping solution are shown in FIG. As the wrap liquid, 250 ml of 0.5 wt% aqueous solution of Na-alkyl-di-phenyl-ether-di-sulfonate (anionic surfactant) and 0,5 alkyl di-methyl betaine (amphoteric surfactant) were used. A solution was prepared by dispersing 0.6 g of diamond abrasive grains having an average particle size of 0.25 μm in 500 ml of an aqueous solution mixed with 250 ml of a 0.5 wt% aqueous solution. Other conditions are the same as the above case.

As can be seen from this figure, when lapping was performed using a lapping solution prepared by mixing an anionic surfactant and an amphoteric surfactant, it was prepared only by the conventional anionic surfactant. It was possible to reduce the processing step of the magnetic head as compared with lapping with a lapping liquid.

Further, FIGS. 18 to 20 show the results of examining the influence of the concentration of the anionic surfactant and the amphoteric surfactant on the processing step. When the amount of the anionic surfactant was large, an adsorption film was easily formed on the surface of the protective film 12 and only the protective film 12 was hard to be lapped, resulting in a large processing step. On the contrary, when the amount of the amphoteric surfactant is large, the adsorption film is likely to be formed on all the surfaces of the magnetic film 11, the protective film 12, and the substrate 13, so that the processing step is reduced.

In particular, the anionic surfactant has a mass of 0.
It was prepared by dispersing 0.6 g of diamond abrasive grains having an average particle size of 0.25 μm in 500 ml of an aqueous solution in which the amount of the amphoteric surfactant is 6% or less and the amount of the amphoteric surfactant is 0.4% or more. When the lapping liquid was used, the processing step 22 could be 0.02 μm or less even when lapping was performed using a conventionally used tin lapping plate. The wrapping conditions are the same as those shown in FIG.

Further, when the lapping liquid of the present embodiment is used and the lapping plate made of tin-brass or tin-copper is used for lapping, the lapping liquid and the lapping plate are separated as shown in FIGS. Due to the synergistic effect, the processing step was further reduced to 0.01 μm or less.

In the above embodiment, the example of polishing the air bearing surface of the thin film magnetic head has been described, but the present invention is not limited to the magnetic head, and may have a portion having different hardness,
The present invention can be applied to lapping a workpiece made of all composite materials having a portion whose surface is positively charged and a portion whose surface is negatively charged in an aqueous solution, thereby reducing a working step.

Next, a polishing apparatus using the lapping plate and lapping liquid described in the above embodiment will be described with reference to FIG.

This polishing apparatus comprises a surface plate 60 and a drive device (not shown) for rotating the surface plate. Further, during processing, a pump 70 for supplying the lapping liquid onto the surface plate,
It has a tube 71 and a tank 72. The jig 6
Reference numeral 2 is for holding the object to be polished, and the correction ring 64 is for preventing uneven wear of the surface plate 60.

At least the surface of the surface plate 60 is made of the above-described material, that is, a sintered material of tin powder and brass powder, or a casting of tin and copper. However, the material is not limited to this, and may be any material as long as it satisfies the above-mentioned conditions regarding hardness and supporting rigidity.

As the lapping liquid, it is preferable to use the lapping liquid described in the above embodiment, but other lapping liquids can of course be used.

The object to be polished is attached to the jig 62 and placed on the surface plate 60. Then, in this state, the working liquid stored in the tank 72, that is, the lapping liquid is supplied onto the surface plate 60. Then, the surface plate 60 is rotated by the driving device. Then, the abrasive grains contained in the lapping liquid enter between the surface plate 60 and the object to be polished and polish the object to be polished.

The polishing apparatus is merely an example,
The specific configuration is not limited to this.

Next, a magnetic recording apparatus using a magnetic head lapped by using the above polishing apparatus will be described with reference to FIG.

The magnetic recording apparatus has a magnetic disk 81 rotatably housed in a housing 80, and a spindle motor 82 for rotating the magnetic disk. Also,
A magnetic head 84 for reading the information recorded on the magnetic disk 81 is held by a swing arm 85, a steel band 86, etc., and a stepper motor 83.
Thus, the magnetic disk 81 is movable along the information recording surface. The operation of each of these units is controlled by a control circuit (not shown) or the like. The magnetic head 84 of this embodiment is polished by using the polishing apparatus described above, and the processing step on the air bearing surface thereof is extremely small. Therefore, the flying height of the magnetic head does not substantially increase due to the processing step, and high-density recording is possible as compared with the related art.

In the magnetic recording device, the magnetic disk 81 is fixed and cannot be replaced, but the user may replace the magnetic disk 81.
Further, other configurations are not limited to those shown in FIG.

[0063]

EFFECTS OF THE INVENTION When polishing is performed using a polishing apparatus using the lapping plate of the present invention, a processing step is unlikely to occur even if the surface to be polished has a different hardness. For example, when it is applied to polishing the air bearing surface of a thin film magnetic head, the conventional value is 0.03.
The processing step, which has been limited to μm, can be reduced to 0.02 μm or less, and thereby the limit value of the recording bit length of the magnetic disk can be shortened by at least 0.05 μm or more.

When polishing is carried out using the lapping liquid of the present invention, a processing step due to the formation of a surfactant adsorption film on the surface to be polished is unlikely to occur.

Further, by using the lapping plate of the present invention and the lapping liquid together, the processing step can be further reduced.

Further, by using the polishing apparatus according to the present invention and the magnetic head having a small processing step polished by using the lapping liquid or the like, a magnetic recording apparatus having a high recording density can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a thin film magnetic head and a processing step.

FIG. 2 is an explanatory diagram showing a principle of generation of a processing step.

FIG. 3 is a schematic view of an indenter indentation experimental device.

FIG. 4 is a characteristic diagram showing a result of pushing an indenter into tin.

FIG. 5 is a characteristic diagram showing a result of pushing an indenter into aluminum.

FIG. 6 is a characteristic diagram showing a result of pushing an indenter into copper.

FIG. 7 is a characteristic diagram showing a result of pushing an indenter into brass.

FIG. 8 is a graph showing machining steps of a magnetic head on various surface plates.

FIG. 9 is a graph showing the maximum height of the air bearing surface of a magnetic head on various surface plates.

FIG. 10 is a structural diagram of a copper-brass sintered alloy that is an example of the present invention.

FIG. 11 is a structural diagram of a tin-copper cast alloy that is an example of the present invention.

FIG. 12 is a graph showing machining steps of a magnetic head lapped by the multi-phase alloy platen of the above example.

FIG. 13 is a graph showing the maximum height of the air bearing surface of a magnetic head lapped by the multiphase alloy plate of the above-described example.

FIG. 14 is an explanatory diagram showing a wrapping state with a lapping solution using an anionic surfactant.

FIG. 15 is an explanatory diagram showing a wrapping state with a lapping solution using a cationic surfactant.

FIG. 16 is a graph showing processing steps when lapping is performed using various lapping liquids.

FIG. 17 is an explanatory diagram showing a lapping state of a thin film magnetic head using a lapping liquid which is an example of the present invention.

FIG. 18 is a graph showing the influence of the surfactant concentration in the lapping liquid of the present invention on the processing step.

FIG. 19 is a graph showing the influence of the surfactant concentration in the lapping liquid of the present invention on the processing step.

FIG. 20 is a graph showing the influence of the surfactant concentration in the wrap solution of the present invention on the processing step.

FIG. 21 is a graph showing processing steps when lapping is performed using the lapping liquid according to the present invention and the brass-tin platen of the present invention.

FIG. 22 is a graph showing working steps when lapping is performed using the lapping liquid according to the present invention and the tin-tin platen of the present invention.

FIG. 23 is an explanatory view showing an example of a polishing apparatus to which the lapping plate according to the present invention is applied.

FIG. 24 is an explanatory diagram showing an example of a magnetic recording apparatus using a lapping plate and a magnetic head wrapped with a lapping liquid according to the present invention.

FIG. 25 is an explanatory diagram of a magnetic head and a magnetic disk.

FIG. 26 is a graph showing the relationship between the flying height of the magnetic head and the recording bit length.

[Explanation of symbols]

1 ... Brass phase, 2 ... Tin phase, 3 ... Tin phase, 4 ... Compound phase of tin and copper, 5 ... Thin film magnetic head, 6 ... Air bearing surface, 11 ... Magnetic film,
12 ... Protective film, 13 ... Substrate, 14 ... Lapping liquid, 15 ... Anionic surfactant, 16 ... Amphoteric surfactant, 17 ... Diamond abrasive, 18 ... Lapping plate, 19 ... Cationic surfactant , 20 ... Flying height, 21 ... Magnetic disk, 22
... Processing step, 23 ... Step, 24 ... Step, 31 ... Diamond indenter, 32 ... Voice coil, 33 ... Differential transformer,
34 ... recorder, 35 ... fulcrum, 36 ... load, 37 ... pushing depth, 60 ... surface plate, 62 ... jig, 64 ... correction ring,
70 ... Pump, 71 ... Tube, 72 ... Tank, 80 ...
Case, 81 ... Magnetic disk, 82 ... Spindle motor,
83 ... Stepper motor, 84 ... Magnetic head, 85 ... Swing arm, 86 ... Steel band

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenya Ohashi, 4026 Kujimachi, Hitachi City, Hitachi, Ibaraki Prefecture, Hitachi Research Laboratory, Hitachi, Ltd. Factory Odawara Factory

Claims (20)

[Claims] 1. In lapping in which a work piece is pressed and slid by interposing free abrasive grains on a lapping plate, the change in the vertical movement amount of the abrasive grains caused by the variation of the lapping force acting on the abrasive grains is tin. Lap surface plate made of smaller material. 2. A lapping method using a lapping plate made of the material according to claim 1. 3. A thin film magnetic head in which the air bearing surface is lapped using the lapping plate according to claim 1. 4. A magnetic disk device equipped with the thin film magnetic head according to claim 3. 5. A lapping plate having at least two phases of the material phase according to claim 1 and a soft metal phase with an HV of 20 or less. 6. A lapping plate made of a material having a tin phase and a brass phase having a mass of copper of 50% or more. 7. A lapping plate made of a casting made by mixing molten tin with 0.7% or more and 7.6% or less of the mass of tin and then cooling the molten copper. 8. A lapping method using the lapping plate according to claim 1, 5, 6, or 7. 9. A thin film magnetic head having an air bearing surface lapped using the lapping plate according to any one of claims 1, 5, 6, and 7. 10. A magnetic disk device equipped with the thin-film magnetic head according to claim 9. 11. A composite material lapped using the lapping plate according to claim 1, 5, 6, or 7. 12. A lapping solution comprising abrasive grains dispersed in an aqueous solution containing an anionic surfactant and an amphoteric surfactant. 13. The lapping liquid according to claim 12, wherein the ratio of the anionic surfactant in the aqueous solution is 0.6 wt% or less. 14. The lapping liquid according to claim 12, wherein the ratio of the amphoteric surfactant in the aqueous solution is 0.4 wt% or more. 15. A lapping method comprising lapping using an anionic surfactant, an amphoteric surfactant, and abrasive grains. 16. A thin film magnetic head characterized in that an air bearing surface is lapped using a lapping liquid containing an anionic surfactant and an amphoteric surfactant. 17. A thin film magnetic head having an air bearing surface lapped using the lapping liquid according to claim 12, 13, and 14 and the lapping plate according to claim 1, 5, 6, or 7. 18. A magnetic recording apparatus comprising the thin film magnetic head according to claim 16 or 17. 19. A composite material, which is lapped with a wrap solution containing an anionic surfactant and an amphoteric surfactant. 20. A composite material which is lapped using a lapping liquid containing an anionic surfactant and an amphoteric surfactant and the lapping plate according to any one of claims 1, 5, 6 and 7.