JPH02216604A - Magnetic head and its production - Google Patents

Abstract

PURPOSE:To obtain a high recording and reproducing performance by forming a pair of first magnetic alloy layers, which are formed on both sides of an operating gap, with a magnetic alloy whose saturation magnetic flux density is higher than that of a pair of second magnetic alloy layers formed on both sides of first magnetic alloy layers. CONSTITUTION:Magnetic alloy parts to be interposed between oxide magnetic cores 1 and 11 and an operating gap 4 consist of first magnetic alloy layers 2 and 21 and a pair of second magnetic alloy layers 3 and 31 formed on both sides of these layers 2 and 21. Glass track width control parts 5 and 51 are formed on both sides of the operating gap 4, and one oxide magnetic core 1 is provided with a coil window 6. Second magnetic alloy layers 3 and 31 consist of a conventionally used sendust, and first magnetic alloy layers 2 and 21 consist of materials where the quantity of Al or Si is smaller and the saturation magnetic flux density is higher in comparison with the sendust. Thus, the linearily of recording intensity of a magnetic tape to a magnetomotive force is improved and the recording and reproducing performance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic head installed in a magnetic recording/reproducing device such as an 8 mm VTR or a digital audio recorder.

(Prior Art) With the advent of magnetic recording media with high coercive force such as metal tapes and vapor-deposited tapes, magnetic alloy materials with high saturation magnetic flux density, such as sendust, are used in place of conventional oxide magnetic heads near the magnetic gap. A so-called composite magnetic head in which a magnetic layer is formed of an amorphous alloy or the like has been developed.

Figures 11(a) and 11(b) show a composite magnetic head used in 8mm VTRs, etc., in which a pair of oxide magnetic cores (1) and (11) made of ferrite etc. , a pair of magnetic alloy layers (
3) (31), and track width regulating parts (5) (51) made of glass are provided on both sides of the operating gap (4). Moreover, a coil window (6) for winding an electric coil is provided in one of the oxide magnetic cores (1).

In the magnetic head described above, the magnetic path near the working gap, which must have a high degree of magnetic saturation due to its structure, is formed of sendust or the like with a high saturation magnetic flux density.
The occurrence of magnetic saturation is suppressed.

(Problem to be Solved) In conventional composite magnetic heads, the magnetic alloy layer has a saturation magnetic flux density Bs of 10,000 to 11°0Q, for example.
Sendust of approximately OG auss is used, and it was conventionally thought that forming a magnetic alloy layer with a saturation magnetic flux density of this level in the vicinity of the working gap was optimal for recording and reproducing performance.

However, according to the magnetic analysis conducted by the inventor as described below, the working gap (
It has become clear that the degree of saturation of the magnetic flux density reaches 98% or more in the vicinity of 4).

When the degree of magnetic saturation becomes extremely high in a part of the magnetic alloy layer in this way, the magnetic permeability of sendust decreases rapidly.As a result, even if the magnetomotive force, that is, the recording current is increased, the leakage magnetic flux involved in recording is almost negligible. If the magnetic tape does not increase, the linearity of the recording strength (recording magnetic field) of the magnetic tape with respect to the magnetomotive force collapses, and distortion occurs in the recording/reproduction waveform of the signal.

However, if the entire magnetic alloy layer (2) (21) is made of a material with an extremely high saturation magnetic flux density of 13,0 OOG auss or more, for example, an alloy of Fe: 94% by weight and SL: 6% by weight, the magnetic saturation However, since such ultra-high saturation magnetic flux density materials generally have low magnetic permeability, this particularly causes a deterioration in signal reproduction performance.

An object of the present invention is to provide a magnetic head that provides higher recording and reproducing performance than conventional magnetic heads, and a method for manufacturing the same.

(Means for Solving the Problems) The present invention provides a pair of head halves facing each other with an operating gap (4) in between, and at least the opposing portions of both head halves.
In the magnetic head in which a magnetic alloy portion is formed, the magnetic alloy portion includes a pair of first magnetic alloy layers (2) and (21) formed on both sides of the working gap (4), and a pair of first magnetic alloy layers (2) and (21) formed on both sides of the working gap (4). Furthermore, a pair of second magnetic alloy layers (3) (31) formed on both sides
The first magnetic alloy layer (2) (21) is characterized in that it is formed from a magnetic alloy having a higher saturation magnetic flux density than the second magnetic alloy layer (3) (31).

Each first magnetic alloy layer (2) (21) has a thickness of, for example, 0.06 μm
It is formed to a thickness greater than or equal to that.

Further, the magnetic head according to the present invention has a pair of head halves facing each other with an operating gap (4) in between, and each head half has an oxide magnetic core (1) (It) that forms a main magnetic path. ), working gap (4) and oxide magnetic core (1) (11)
and a magnetic layer interposed between the
From the oxide magnetic core (1) (11) side to the working gap (4
) is formed of a magnetic alloy layer in which the Fe content gradually increases toward the side.

The method for manufacturing the magnetic head described above includes an oxide magnetic core (1) (
11) In the process of forming the magnetic alloy that will become the magnetic layer to a predetermined thickness on the surface of the magnetic substrate using vacuum thin film formation technology, the absolute value of the magnetic substrate changes continuously or stepwise. It is characterized by applying an increasing negative bias voltage.

(Functions and Effects) In the above magnetic head, the first magnetic alloy layers (2) (21) arranged on both sides of the working gap (4) are connected to the second magnetic alloy layers (3) (31) made of sendust or the like. Since the saturation magnetic flux density is higher than that of conventional composite magnetic heads, the degree of magnetic saturation is lower than that of conventional composite magnetic heads.Therefore, the linearity of the recording strength of the magnetic tape with respect to the magnetomotive force is good, and the recording and reproducing performance is improved. .

In addition, by setting the thickness of the first magnetic alloy layer (2) (21) to an appropriate value in relation to the optimum gap length as described later, the magnetic flux from the recording medium during signal reproduction can be It is possible to increase the proportion of effective magnetic flux that can be extracted as a signal, thereby improving signal reproduction performance.

The above effects are such that the magnetic layer between the oxide magnetic cores (1) (11) and the working gap (4)
1) From the (11) side to the operating gap (4) side
The same applies to magnetic heads formed of magnetic alloy layers whose e content gradually increases.

In addition, in the method for manufacturing a magnetic head according to the present invention, for example, when Sendust is used as the magnetic alloy, the bias voltage to be applied to the magnetic substrate is first set to zero volts, and film formation is performed, unlike conventional methods. Same composition as (Fe: approx. 83
After that, by setting the bias voltage to, for example, 100 V, a magnetic alloy film with increased Fe content (approximately 85 wt % Fe) is obtained. Note that by continuously changing the bias voltage, it is possible to gradually increase the Fe component toward the film surface layer.

Therefore, in the finally completed magnetic head, magnetic alloy layers having a higher saturation magnetic flux density than Sendust are formed on both sides of the working gap, and the above effects are exhibited during recording and reproduction.

(Examples) The examples described below are for illustrating the present invention, and should not be construed as limiting the invention described in the claims or reducing its scope.

First, magnetic analysis of a conventional magnetic head performed in the process of completing the present invention will be described.

Using the composite magnetic head shown in FIGS. 11(a) and 11(b) as a model, oxide magnetic cores (1) and (11) are made of ferrite with a saturation magnetic flux density of 5,000 G auss, and a magnetic alloy layer (
3) The saturation magnetic flux density in (31) is 10,0OOG aus
S sendust was used, and the film thickness of the magnetic alloy layer was 5 μm.
One gap length was set to 0.28 μm. Furthermore, the magnetomotive force on the head is 5,000 Gauss at the boundary between the oxide magnetic cores (1) (11) and the magnetic alloy layers (3) (31).
It was set to be s.

A magnetic analysis simulation using the finite element method was performed on the above magnetic head model. At this time, as shown in Fig. 4, the size of the element is 0.02 μm x 0.02 μm, which is even smaller than what was conventionally done.
In the approximately triangular area with a width of 0.06 μm and a depth of 0.08 μm hatched in Figure 4, the magnetic flux density is 98.0 μm.
This analysis revealed for the first time that the saturation level exceeds 00 Gauss and saturation is 98% or higher.

As a result, in the conventional magnetic head, the linearity of the recording strength with respect to the magnetomotive force was broken.

Therefore, in the present invention, the magnetic saturation degree is at least 98.
The above problem was solved by forming a magnetic alloy with an ultra-high saturation magnetic flux density, which has a saturation magnetic flux density even higher than that of a high saturation magnetic flux density material such as Sendust, in the region where the saturation magnetic flux density exceeds %.

As shown in FIGS. 1 and 2, for example, the magnetic head of the present invention has a pair of oxide magnetic cores (1) and (11) facing each other with an operating gap (4) in between. 1)
(11) and the working gap (4) are a pair of first magnetic alloy layers (2) and (21) formed on both sides of the working gap (4), and the first magnetic alloy layer (21) formed on both sides of the working gap (4). A pair of second magnetic alloy layers (3) (31) formed on both sides of the magnetic alloy film
).

Track width regulating parts (5) (51) made of glass are formed on both sides of the working gap (4), and a coil window (6) is opened in one of the oxide magnetic cores (1).

The oxide magnetic cores (1) and (11) are made of Mn-Zn with a saturation magnetic flux density of about 5°000 to 5.800 Gauss.
It is formed from single crystal ferrite or high density ferrite.

For the second magnetic alloy layers (3) and (31), Sendust, which has been used conventionally, is used, for example, Sendust consisting of 84% by weight of Fe, 6% by weight of A1, and 10% by weight of Si.

Here, it is also possible to partially replace Fe (3% by weight or less) with Cr. In this case, the saturation magnetic flux density is 10.0
00 to 11,000 Gauss.

Examples of materials for the first magnetic alloy layer (2) (21) include Fe-SL alloy, Fe-A 1 alloy, Fe-A
I-8i alloy etc. can be used, and these alloys are
The saturation magnetic flux density is increased by decreasing A1 and SL compared to the components of the sendust.

For example, the components of Fe-A1 alloy are Fe: 94% by weight, S
i: Set to 6% by weight. This will result in 18.000
A saturation magnetic flux density on the order of Gauss can be obtained.

Furthermore, as the material for the first magnetic alloy layer (2) (21), F
e, or Cr5Ti for Fr-Co alloys.

It is also possible to use a material with various additives such as Rh, Pt, and V added, which increases the saturation magnetic flux density to 12
, 000 to 20,000 Gauss.

When selecting materials for the first magnetic alloy layers (2) (21), not only the value of saturation magnetic flux density but also magnetic permeability, wear resistance, etc. are taken into consideration.

The thickness of each first magnetic alloy layer (2) (21) is 0.06~
formed in a range of 1 μm (for example 0.2 μm), and each second
The thickness of the magnetic alloy layer (3) (31) is formed in a range of 3 to 10 μm (for example, 6 μff1).

FIG. 5 shows the frequency characteristics of magnetic permeability of the Sendust and Fe-Si alloys. In this way, the magnetic permeability of the Fe-Si alloy is lower than that of Sendust at frequencies below approximately 3 MHz. Therefore, the first magnetic alloy layer (2) (2
If 1) is formed extremely thick, the signal reproduction performance of the magnetic head will deteriorate.

Figure 3 shows the first magnetic alloy layer (2) during signal reproduction.
(21) and the magnetization direction of the magnetic tape (7) on the second magnetic alloy layer (3) (31), and the state of the magnetic flux within the magnetic head generated thereby. Here, when the thickness of the first magnetic alloy layer (2) (21) is as thin as tl<0.06 μm, the magnetic saturation near the working gap (4) exceeds 98% as described above, and Even if t, > 0.06 μm, if it is too thin, the invalid magnetic flux shown by the broken line in the figure increases. On the other hand, if the thickness of the first magnetic alloy layer (2) (21) is too thick, for example, t, >1 μm, the magnetic resistance of the effective magnetic flux shown by the solid line in the figure increases.

Therefore, in the present invention, the first magnetic alloy layer (2
) (21) was used to define the thickness.

Generally, in a magnetic head, the frequency F of the recording signal,
The relationship V=FXλ holds between the recording wavelength λ of the signal and the magnetic tape speed V with respect to the magnetic head.

In addition, the gap length is generally 1/2 to 1/3 of the recording wavelength λ.
The value of is considered to be the optimum value (see, for example, "Magnetic Head and Magnetic Recording" by Mitsukoshi Matsumoto, General Electronic Publishing, p. 99).

Here, the optimal value g0 of the gap length is selected as 1/2 of λ,
F = 3 MHz, V = 3.75 m/se
c, then from the above relational expression, the optimal gap length g0#0
．． 62 μm is obtained.

In the magnetic head of the present invention, as shown in FIG.
By setting it to 0, it is possible to improve the recording and reproducing performance as described above. Therefore, in the above example,
If the actual gap length g is 03 μm, the optimum width t0 of each first magnetic alloy layer (2) (21) is approximately 0.16 μm.

Incidentally, even if the width of the first magnetic alloy layer (2) (21) deviates somewhat from the above-mentioned optimum width, it is of course possible to obtain better recording and reproducing performance than the conventional magnetic head.

Next, the magnetic tape to be recorded or reproduced by the magnetic head of the present invention will be considered.

The graph in Figure 6 shows that the saturation magnetic flux density is 10 as shown in the figure.
, 000 Gauss second magnetic alloy layer (3) (3
1) with a thickness of 0.224 m and a saturation magnetic flux density of 1
8,000 Gauss first magnetic alloy layer (2) (21)
In the magnetic head of the present invention, which is equipped with It shows how much the magnetic flux density increases at the height h from the contact surface.

As is clear from this graph, a particularly high increase in magnetic flux density is observed when the height h from the tape contact surface is 0.15 μm or less.

By the way, regarding vapor-deposited tapes and vapor-deposited disks, which have recently attracted attention as recording media with high coercive force,
A ferromagnetic metal thin film with an extremely thin thickness of about 0.15 μm is formed as the magnetic layer.

Therefore, by employing the magnetic head of the present invention, which generates a high magnetic flux density in a height range of up to 0.15 μm from the tape contact surface, as a recording/reproducing head for vapor-deposited tape, the performance of the vapor-deposited tape can be fully brought out. I can do it.

Incidentally, the oxide magnetic cores (1) (11) and the second magnetic alloy layers (3) (31) shown in FIG. ) can be made of a magnetic alloy with a saturation magnetic flux density even higher than that of Sendust, and it goes without saying that the same effect as described above can be obtained in the magnetic head.

Next, the first magnetic alloy layer (2) of the magnetic head according to the present invention
A method for forming (21) and the second magnetic alloy layers (3) and (31) using a vacuum thin film forming technique such as sputtering will be described.

10(a) to (d) show the overall flow of the manufacturing process of the magnetic head shown in FIG. 1, and except for the thin film forming process shown in FIG. 10(a), the conventional manufacturing process is is the same as

As shown in FIG. 10(a), a pair of ferrite wafers (1
2) First, sendust films (32) and (33), which will become the second magnetic alloy layer, are formed on the surface of (13) by DC bias sputtering as described later, and then the first magnetic alloy layer is formed on the surface. Fe-A I-8i film (22) (2
3) Form.

Furthermore, a SiO2 film (not shown) is formed on the surface as a gap spacer.

Next, as shown in the same figure (b), one of the ferrite wafers (
A plurality of track width regulating grooves (5) are formed on the film surface of 12).
2) and the other ferrite wafer (13
), multiple track width regulating grooves (5
3), and a plurality of coil grooves (61) and joining grooves (62) extending in a direction perpendicular to this are recessed.

These grooves can be formed, for example, by chemical etching for the sendust film or the like, and by machining using a diamond grindstone or the like for the ferrite portion.

Next, a pair of ferrite wafers (12) that have undergone the above steps
The wafers (13) are superimposed as shown in FIG.
Fill it with.

Finally, the head block obtained through the above steps is sliced along the broken lines in the figure, and the head chip thus obtained is subjected to necessary shaping processing to complete the magnetic head shown in Fig. 1. .

When forming the sendust film and the Fe-A I-8i film, a magnetic alloy is used depending on the composition of each film,
By repeating the conventional sputtering method twice,
Although this can be done easily, in this example, a method was developed and adopted in which the two types of thin films mentioned above are continuously formed by using a so-called bias sputtering method.

FIG. 7 and FIG. 8 show Sendust film and F e-A l-
3 shows a schematic configuration of a DC bias sputtering device used to form a 3i film.

This device is generally called a facing target type sputtering device, and as shown in FIG. 7, in a vacuum container (8),
A pair of targets (81) (82) are arranged facing each other, and an electrically insulating plate (82) is arranged facing the space between both targets.
5) A metal substrate holder (83) equipped with a fixing fitting (84) is attached on top. Board holder (83)
A bias power supply (86) whose voltage can be adjusted is connected to.

As shown in Figure 8, the ferrite wafer (
12) is mounted and fixed with the fixing metal fittings (84), a voltage of approximately -800 cm is applied to the target, and while changing the voltage value of the bias power supply as described below, Perform sputtering.

In this example, F is used as the target (81) (82).
e: 84% by weight, A1: 6% by weight, Si: 10% by weight
First, the bias voltage is set to Ov and sputtering is performed for a predetermined time, and then the bias voltage is set to -100V and sputtering is performed for a predetermined time.

For the following clothing 1, in the above device, the bias voltage is set to 0,
The graph shows the composition and saturation magnetic flux density of alloy films obtained when sputtering is performed at voltages of -50V and -100V.

(Left below) Table 1 FIG. 9 shows the frequency characteristics of the relative magnetic permeability of these three types of alloy films.

Therefore, by first performing sputtering with the bias voltage set to Ov as described above, a normal sendust film (for example, 5.8 μm thick) with high magnetic permeability can be obtained.
By setting the bias voltage to -100 V, a magnetic alloy film with a high saturation magnetic flux density (for example, 0.2 μm thick) can be obtained, and by further performing the steps shown in FIG. 10,
The sendust film forms the second magnetic alloy layer (3) (3) in FIG.
1), the magnetic alloy film becomes the first magnetic alloy layer (2) (21) of FIG. 1, and the magnetic head of FIG. 1 is completed.

The composition of the target is not limited to sendust but also CoZr.
It is also possible to use amorphous alloys such as Fe5iGaLu alloys, etc.

Thin film formation techniques that can be used include not only the DC bias sputtering method, but also the well-known two-pole sputtering method, three-pole sputtering method, vacuum evaporation method, etc.
As the bias method, well-known alternating current bias method, ion gun method, etc. can be used.

Furthermore, in the thin film forming process described above, the bias voltage is switched in two stages, but it is also possible to change it in three stages, or four or more stages as shown in Table 1 and FIG. Thus, it is possible to obtain a multilayered magnetic film having different saturation magnetic flux densities and magnetic permeabilities.

Furthermore, it is also possible to manufacture a magnetic head that achieves the same effect as the magnetic head shown in FIG. 1 by continuously changing the bias voltage from Ov to -100V. That is, in the magnetic head, the magnetic layer between the working gap (4) and the oxide magnetic cores (1) and (11) extends from the working gap (4) from the oxide magnetic core (1) and (11) side. ) is formed by a magnetic alloy layer in which the Fe content gradually increases toward the side.

The drawings and the description of the above embodiments are for illustrating the present invention, and do not limit the invention described in the claims.
Nor should it be construed as limiting the scope.

Further, it goes without saying that the configuration of each part of the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the technical scope of the claims.

For example, in the magnetic head shown in FIG. 1, the interface between the oxide magnetic core (1) (11) and the second magnetic alloy layer (3) (31) is the formation surface of the working gap (4). Although they are formed in parallel, it is of course applicable to a magnetic head in which part or all of the boundary surfaces are non-parallel to the gap forming surface, as shown in FIGS. 12 to 15.

[Brief Description of the Drawings] Fig. 1 is an enlarged plan view showing the main parts of the magnetic head according to the present invention, Fig. 2 is an oblique view of the magnetic head, and Fig. 3 shows the state of magnetic flux within the magnetic head. Figure 4 is a diagram explaining the results of magnetic analysis, Figure 5 is a graph showing the frequency characteristics of magnetic permeability, and Figure 6 is a graph showing the relationship between the height from the tape contact surface and the increase in magnetic flux density. 7 is a configuration diagram of the DC bias sputtering device, FIG. 8 is a perspective view of a ferrite wafer fixed on a holder, and FIG. 9 is a graph showing the relationship between bias voltage and relative magnetic permeability. Figure 10(a) (
b) (c) is a perspective view showing the manufacturing process of a magnetic head, FIG. 11(a) is a perspective view of a conventional magnetic head, and FIG.
b) is a plan view showing essential parts of the magnetic head, and FIGS. 12 to 15 are plan views similar to FIG. 1 showing other embodiments of the present invention. (1) (11)...Oxide magnetic core (2) (21)...First magnetic alloy layer (3) (31)...Second magnetic alloy layer (4)...Working gap ( a) Figure 8 Frequency (MHz) Figure 9 (C) Chi, 7'' Figure 10 Procedural Amendment (Spontaneous) April 22, 1989 1, Indication of Case 2, Name of Invention Patent Application Hei 1- 39090 Magnetic head and its manufacturing method (2) Corrected r98,0OOJ to j9,800J on page 10, line 5 of the specification. (3) Corrected "Sendas" to "Sendust" on page 11, line 10 of the specification. Relationship with the case of the person making the amendment Patent applicant (188) SANYO Electric Co., Ltd. Drawings to be amended, details of the amendment in the detailed description of the invention column in the specification

Claims (1)

[Scope of Claims] [1] A magnetic head in which a pair of head halves are disposed facing each other with an operating gap (4) in between, and a magnetic alloy portion is formed at least in the opposing portions of both head halves. The magnetic alloy part includes a pair of first magnetic alloy layers (2) (21) formed on both sides of the working gap (4), and a pair of second magnetic alloy layers (2) formed on both sides of the first magnetic alloy film. 3) (31), and the first magnetic alloy layer (2) (21) is formed from a magnetic alloy having a higher saturation magnetic flux density than the second magnetic alloy layer (3) (31). magnetic head. [2] In a magnetic head in which a pair of head halves are arranged facing each other with an operating gap (4) in between, each head half has an oxide magnetic core (1) (11) and an oxide magnetic core (1) (11) that forms a main magnetic path. , a first magnetic alloy layer (2) disposed facing the working gap (4).
) (21) and second magnetic alloy layers (3) (31) disposed between the oxide magnetic cores (1) (11) and the first magnetic alloy layers (2) (21). , a magnetic head characterized in that the first magnetic alloy layer (2) (21) is formed of a magnetic alloy having a higher saturation magnetic flux density than the second magnetic alloy layer (3) (31). [3] The thickness of each first magnetic alloy layer (2) (21) is 0.0
The magnetic head according to claim 1 or 2, which has a diameter of 6 μm or more. [4] A pair of head halves are arranged facing each other with a working gap (4) in between, and each head half has an oxide magnetic core (1) (11) to form a main magnetic path and a working gap (4). ) and a magnetic layer interposed between the oxide magnetic cores (1) and (11), the magnetic layer is actuated from the oxide magnetic cores (1) and (11) side. Gap (4)
A magnetic head characterized in that it is formed of a magnetic alloy layer in which the Fe content gradually increases toward the side. [5] A pair of head halves are arranged facing each other with a working gap (4) in between, and each head half has an oxide magnetic core (1) (11) that forms a main magnetic path and a working gap (4). ) and a magnetic alloy layer interposed between the oxide magnetic cores (1) and (11). In the process of forming a magnetic alloy, which will become the magnetic alloy layer, on the surface of the substrate to a predetermined thickness using vacuum thin film formation technology, a negative magnetic alloy whose absolute value increases continuously or stepwise is applied to the magnetic substrate. A method of manufacturing a magnetic head, the method comprising applying a bias voltage.