JPH025206A - Production of magnetic head - Google Patents

Abstract

PURPOSE:To improve the adhesive properties between a soft magnetic thin film and a ferrite core and to reduce the output level fluctuation of the frequency characteristics of the reproduction output for a magnetic head by applying a heat treatment to the ferrite core in an oxygen atmosphere before a film production process. CONSTITUTION:The heat treatment is applied to the ferrite core blocks 1' and 2' that undergone the track width working in an air atmosphere of 500 deg.C, for example, for 15 minutes. Thus the deteriorated layers 1a and 2a are formed on the gap forming surfaces 7 and 7. In such a way, the layers 1a and 2a are formed on the blocks 1' and 2' respectively before a soft magnetic metallic thin film 3 is formed. As a result, the adhesive properties can be improved between the film 3 and both blocks 1' and 2'. Then the deterioration of said adhesive properties can be avoided even through a sputter etching process, etc., are frequency carried out to eliminate the working strain layers. Then it is possible to reduce the output level fluctuation of the frequency characteristics of the reproduction output for a magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic head in which a thin metal film is provided in a gap portion.

[Conventional technology]

In recent years, magnetic recording has become widely used by the general public, as seen in the increased demand for video tape recorders, etc., and along with this, demands for longer recording times and compactness have arisen. Therefore, there is an increasing demand for increasing the recording density. In order to increase this recording density, the coercive force of magnetic media tends to increase.
On the other hand, a magnetic head is necessarily required to have a large magnetic flux density value, and for this reason, a composite magnetic head has been proposed, which is a metal in gap mill head in which a metal thin film is provided in the gap portion.

For example, as shown in FIG. 5, such a composite magnetic head includes two high-permeability ferrite cores 11 and 2, each having a soft magnetic metal thin film 13 having high magnetic flux density and high magnetic permeability formed on their opposing surfaces. 12 are bonded together via a low melting point glass 16, and a magnetic gap 14 is formed at the top of the bonded surface. In addition, a coil winding window 15 for winding a coil is formed in one of the ferrite cores 11, and a coil (not shown) is wound in the constricted portion formed by this coil winding window 15. .

However, in a magnetic head having such a structure, a process-strained layer (not shown) corresponding to a non-magnetic layer tends to be formed at the junction between the soft magnetic metal thin film 13 and the ferrite cores 11 and 12. If a process-strained layer is formed, this will form a pseudo gap. For this reason, reproduction is performed with the pseudo gap before and after reproduction with the magnetic gap 14, resulting in a problem of inducing large fluctuations in the output level in the frequency characteristics of the reproduced output.

Therefore, in order to avoid the output fluctuation of the above frequency characteristics,
As shown in FIG. 6, there is a magnetic head configured such that the pseudo gap surface is non-parallel to the original magnetic gap 14, and as shown in FIG. A magnetic head is constructed by forming a soft magnetic metal thin film 13 after roughening the joint surface with the ferrite cores 11 and 12, and furthermore, in order to reduce the processing strain layer, the soft magnetic metal thin film 13 on the ferrite cores 11 and 12 is A manufacturing method is known in which the soft magnetic metal thin film 13 is formed after sputter etching or the like is performed in advance on the bonding surface with the soft magnetic metal thin film 13.

[Problem to be solved by the invention]

However, for the above-mentioned non-parallel-processed magnetic heads and uneven-processed magnetic heads, the number of manufacturing steps increases dramatically due to such processing, resulting in lower production efficiency and higher prices. . In addition, if only the sputter etching described above is performed, even if the processed strain layer is completely removed, the adhesion between the ferrite cores 11 and 12 and the soft magnetic metal thin film 13 will deteriorate, and the reproduction output level will deteriorate. This has led to the problem of large fluctuations in the

[Means to solve the problem]

In order to solve the above-mentioned problems, the method for manufacturing a magnetic head according to the present invention includes a step of forming a soft magnetic thin film with a high magnetic flux density on each of the opposing surfaces of a pair of ferrite cores forming a magnetic gap. The method for manufacturing a magnetic head having the present invention is characterized by comprising a heat treatment step of subjecting the ferrite core to heat treatment in an oxygen atmosphere before the film forming step.

[For production]

According to the above configuration, the ferrite core is heat-treated in an oxygen atmosphere before the soft magnetic thin film forming process.
An altered layer having certain properties can be obtained on the surface of the soft magnetic thin film on which it is deposited. By forming a soft magnetic thin film through this altered layer, the adhesion between the soft magnetic thin film and the ferrite core can be significantly improved. As a result, even if sputter etching or the like is sufficiently performed to remove the processed strain layer, deterioration in adhesion can be avoided, and output level fluctuations in the frequency characteristics of the reproduced output of the magnetic head can be reduced. Further, since the manufacturing process of the magnetic helad is not so complicated since the process of heat-treating the ferrite core is only increased, the price of the magnetic head does not become relatively high.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

As shown in FIG. 4, the magnetic head manufactured by the method for manufacturing a magnetic head according to the present invention consists of soft magnetic metal thin films 3 having high magnetic flux density and high magnetic permeability on mutually opposing surfaces (gap forming surfaces). A pair of high magnetic permeability ferrite cores 2 thus formed are joined together via a low melting point glass 6, and a magnetic gap 4 is formed at the end of the joined region. Then, altered layers 1a and 2a are formed on the bonding surface (gap forming surface) with each soft magnetic metal thin film 11A3 in the ferrite core 2, and the soft magnetic metal thin film 3 has such altered layers 1a and 2a. The films are respectively formed on the ferrite core 2 via the ferrite cores 2. Further, a coil winding window 5 for winding a coil is formed in one of the ferrite cores 1, and a coil (not shown) is wound in the narrowed part of the coil winding window 5. .

In order to manufacture a magnetic head, FIGS. 1(a) and (b)
As shown in , after the gap forming surfaces 7 and 7 of the ferrite core blocks 1' and 2' are precisely polished by mechanical processing, the processed strained layer (not shown) due to this polishing is chemically etched (adopted in this example). Almost completely removed by etching or sputter etching. RHEED indicates whether it has been removed or not.
(electron beam diffraction method). Thereafter, a groove 5' that will become the coil winding window 5 is formed in one ferrite core block 1'.

Next, as shown in FIGS. 2(a) and 2(b), each of the above ferrite core blocks 1' and 2' was
Perform track width processing.

Then, as shown in FIGS. 3(a) and 3(b), the ferrite core block 1' which has been subjected to the track width processing is
・For example, heat treatment is performed for 15 minutes in an air atmosphere at 500° C. to the gap forming surfaces 7 and 7.
The altered layers 1a and 2a are formed.

After forming a sendust film as a soft magnetic metal thin film 3 on each of the degraded layers 1a and 2a of the ferrite core blocks 1' and 2' processed and treated as described above by sputtering, the ferrite core block 1 ' and 2' are pasted together via a gap material so that their gap forming surfaces 7 and 7 face each other. At this time,
A magnetic gap 4 is formed. After that, a cylindrical polishing process,
After passing through the chip slicing process and the sliding surface polishing process, a magnetic head is obtained by winding the constricted portion formed by the coil winding window 5.

In this way, before the process of forming the soft magnetic metal thin film 3, the ferrite core blocks 1' and 2' are heat-treated in an air (oxygen) atmosphere to obtain the modified Jiila 2a. It was possible to improve the adhesion between the soft magnetic metal thin film 3 and the ferrite core blocks 1' and 2'. The improvement in adhesion is confirmed by increasing the total stress of the soft magnetic metal thin film 3 to be formed and comparing the results.

Specifically, we will compare how thick a sendust film can be formed on a ferrite core block. The experimental results show that the thickness of the sendust film formed on a ferrite core block that has not been heat-treated is approximately 30% smaller than the thickness of the sendust film that is formed on a ferrite core block that has been heat-treated. It was confirmed.

This is due to the fact that altered layers 1a and 2a were obtained by heat treatment, but only when altered layers 1a and 2a are completely nonmagnetic layers and altered layers 1a and 2a
If the thickness of a is too thick, such altered layers 1a and 2a
On the contrary, there is a risk that it may function as a pseudo gap and have an adverse effect. For this reason, it is desirable to set the thickness of the above-mentioned altered 1iJ1a2a to about 1000 or less.

The reason for this is explained below, but here, the maximum value of the leakage magnetic field strength in the direction perpendicular to the gap, which can be obtained analytically using the simplest model, is It is expressed by the first equation on the center line of .

H=(Bs/πμoμt)jan-'(g'/2y)
＋＋＊＋＊tm First equation However, the magnetic permeability of the magnetic core is infinite, and Bs is the saturation magnetic flux density [T] of the magnetic core, μ. is the vacuum permeability, go is the thickness of the insulation N (altered layer) [μm]・μi
is the relative magnetic permeability of the insulating layer, and y is the position [μm] on the gap center line.

In this case, if the above-mentioned magnetic field H is equal to or less than the coercive force Hc of the recording medium, the influence on the magnetization state is small. Therefore, ti<
According to TLC, the thickness go of the wA green layer must satisfy the following 2nd condition.

go<2ytan(πμ.μtHc/Bs)・・・・・・
......The second equation y is the position on the gap center line, so if we consider this y to be the gap between the magnetic head and the recording medium and set this value to about 0.05 μm, go is as follows: It is sufficient if the third formula is satisfied.

g'<0. I X tan(πμo p Jc/Bs
) ・” ”・Equation 3 Based on these equations, considering the case where a metal tape is used as the recording medium and a sendust film is used as the soft magnetic metal thin film, the thickness of the above-mentioned deteriorated layer is about 1000. In addition, in order to make the thickness of the altered layer about 1000, it was suitable to set the temperature at about 600° C. in the heating step.

The above is an explanation for recording, and the relative magnetic permeability of the altered layer is assumed to be μ,·1.

During reproduction, considering that the above-mentioned μ diagonal is actually several tens, and considering the efficiency of the magnetic circuit formed by the pseudo gap and the original magnetic gap, it is found that when μ5 = 1, the above-mentioned altered layer Since a undulation of approximately 1 dB is detected when the thickness of the layer is 100, the thickness of the altered layer is 1000.
It is desirable to set it to Å or less.

As a result of comparing the reproduction output between the magnetic head manufactured by the method of this example and a conventional magnetic head that has not been subjected to heat treatment, the former magnetic head has a reproduction output of 0.5 to 1.0 dB, and the latter magnetic head has a reproduction output of 0.5 to 1.0 dB. It was found that there was a considerable difference in the quality of the reproduced signals, such as 3.0 to 4.0 dB.

〔Effect of the invention〕

As described above, the method for manufacturing a magnetic head according to the present invention includes:
In a method for manufacturing a magnetic head, which includes a step of forming a soft magnetic thin film with a high magnetic flux density on each of the mutually opposing surfaces of a pair of ferrite cores forming a magnetic gear, the ferrite core is formed before the film forming step. This configuration includes a heat treatment step in which the core is heat treated in an oxygen atmosphere.

As a result, the adhesion between the soft magnetic thin film and the ferrite core can be significantly improved, and the frequency characteristics of the reproduction output of the magnetic head are fully processed by sputter etching to remove the processed strain layer. can reduce output level fluctuations. Furthermore, since the manufacturing process of the magnetic head is not so complicated since the process of heat-treating the ferrite core is only increased, the price of the magnetic head does not become relatively high. It is particularly effective in manufacturing magnetic heads compatible with high-density recording used in the field of digital magnetic recording.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, and FIG. 1(a) is a perspective view of one ferrite core block in which a groove serving as a coil winding window is formed; (b)
2 is a perspective view showing the other ferrite core block from which the processed strain layer has been removed by etching, FIG. 2(a) is a perspective view of one ferrite core block from which the track width has been processed, and FIG. Figure 3(a) is a perspective view of the other ferrite core block that has undergone width processing, and Figure 3(a) is a perspective view of one ferrite core block in which a modified layer has been formed by heat treatment. FIG. 4 is a perspective view of the magnetic head, and FIGS. 5 to 7 are perspective views of the magnetic head manufactured by the conventional manufacturing method. 1 and 2 are ferrite cores, 1' and 2' are ferrite core blocks, 3 is a soft magnetic metal thin film (soft magnetic thin film), 4 is a magnetic gap, 5 is a coil winding window, 5' is a groove, and 6 is a low melting point Glass, 7 is a gap forming surface. Patent applicant Sharp Co., Ltd.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a magnetic head comprising the step of forming a soft magnetic thin film with a high magnetic flux density on each of the mutually opposing surfaces of a pair of ferrite cores forming a magnetic gap, the above film forming step A method for manufacturing a magnetic head, comprising a heat treatment step of subjecting the ferrite core to heat treatment in an oxygen atmosphere before the step.