JPH06224039A - Soft magnetic thin film and magnetic head - Google Patents

Abstract

PURPOSE:To obtain a soft magnetic thin film, which is low in saturation magnetic flux density and is superior in heat resistance, by a method wherein the soft magnetic thin film has a composition, which is shown by CoxMyCz, where M is a specified element, and x, y and z are proportions. CONSTITUTION:A soft magnetic thin film has a composition, which is shown by CoxMyCz where M is one kind of an element or more of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W and Y, and x, y and z (an atomic %) satisfy 50<=x<=82, 18<=y<=30, 0.1<=z<=20 and x+y+z=100. The film has a saturation magnetic flux density Bs of 0.45 T or lower. A magnetic head is formed using this soft magnetic thin film. Thereby, the soft magnetic thin film, which has the low Bs and is superior in heat resistance, can be obtained and if this soft magnetic thin film is used, a close contact glass, which is good in environmental resistance and is high in mechanical strength, can be used at the time of manufacture of the magnetic head and the magnetic head, which is highly reliable and has a high yield of manufacture, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic thin film and a magnetic head using the same.

[0002]

2. Description of the Related Art FDD (floppy disk drive)
, HDD (hard disk drive), VTR, DA
Various magnetic heads are used in various magnetic recording / reproducing devices such as T (digital audio tape recorder).

Such magnetic heads include DGL (dual gap length) type magnetic heads and EDGs.
There is a so-called (Enhanced Dual Gap Length) type magnetic head.

The DGL type magnetic head has a pair of ferrite cores provided with a soft magnetic thin film having a saturation magnetic flux density Bs lower than that of the cores on at least one of the facing surfaces of the gap.

In the magnetic head having such a structure, the low Bs soft magnetic thin film is saturated during recording, while it is not saturated during reproduction, so that it can be used as a wide gap during recording and as a narrow gap during reproduction. Therefore, the DGL type recording / reproducing head can obtain the same performance as the recording-only head and the reproduction-only head.

The EDG type magnetic head is the same as the DGL type magnetic head, in which a high Bs soft magnetic thin film having Bs higher than that of the core is further formed in the gap part of the core facing the low Bs soft magnetic thin film. In addition to the advantage of the DGL type, there is an advantage that a strong magnetic flux can be applied to the magnetic recording medium from the high Bs soft magnetic thin film, so that effective recording can be performed on the medium having high coercive force.

In the low Bs soft magnetic thin film in such a magnetic head, a Co type amorphous material has been conventionally used because it has a high magnetic permeability and a low saturation magnetic flux density.

By the way, these magnetic heads are manufactured by forming the above-mentioned various soft magnetic thin films on the surfaces of the cores facing the gap portion and then welding a pair of cores with glass.

The glass is preferably welded at a high temperature, but with the above Co-based amorphous material, the temperature is 600 ° C.
When the heat treatment is performed as described above, the soft magnetic characteristics are significantly deteriorated due to the crystallization of the film, so that the welding temperature in the glass welding step is limited to less than 600 ° C.

In order to obtain a so-called low melting point glass having a welding temperature of less than 600 ° C., it is necessary to add a large amount of lead, alkali metal, etc., so that the environment resistance such as humidity resistance becomes insufficient, and the machine The target strength is also reduced. Therefore, conventionally,
Glass used as a fused glass has low environmental resistance and poor mechanical strength. For this reason, the magnetic head using the soft magnetic thin film of the Co-based amorphous material has low reliability and low manufacturing yield.

[0011]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a soft magnetic thin film having low Bs and excellent heat resistance.

A second object of the present invention is to provide an EDG type or DGL type magnetic head using this soft magnetic thin film, which is excellent in electromagnetic conversion characteristics and reliability and has a good yield.

[0013]

These objects are achieved by the present invention described in (1) to (5) below. _{(1) Co x M y C} z [wherein, M is Ti, V, Cr,
1 of Zr, Nb, Mo, Hf, Ta, W and Y
More than one kind, and x, y and z are composition ratios (atomic%), respectively. ], X, y and z have a relationship of 50 ≦ x ≦ 82 18 ≦ y ≦ 30 0.1 ≦ z ≦ 20 x + y + z = 100, and the saturation magnetic flux density Bs is 0. A soft magnetic thin film of 45T or less.

(2) M is a combination of at least one of Zr, Hf, Ti and Y and at least one of Nb, Mo, Cr, V, Ta and W. ) Soft magnetic thin film.

(3) Co _x M ¹ _a M ² _b C _z [where M ¹
Is one or more of Zr, Hf, Ti and Y,
M ² is one of Nb, Mo, Cr, V, Ta and W
More than one kind, and x, a, b and z are composition ratios (atomic%), respectively. ], And x,
The soft magnetic thin film according to (1) or (2) above, wherein a, b and z have a relationship of 50 ≦ x ≦ 82 18 ≦ a + b ≦ 30 | a−b | ≦ 10 0.1 ≦ z ≦ 20 x + a + b + z = 100. .

(4) The soft magnetic thin film according to any one of (1) to (3) above, which is obtained by forming a thin film having the above composition and then heat treating it at a temperature of 300 to 750 ° C.

(5) A magnetic head having the soft magnetic thin film according to any one of (1) to (4) above.

In Japanese Patent Application Laid-Open No. 2-123507, "a pair of magnetic core halves each having a soft magnetic film formed on the gap side is joined to the soft magnetic film via the gap by glass bonding. In the magnetic head
The soft magnetic film has Co _x M _z C _w (M is at least one selected from Ti, Zr, Hf, Nb, Ta, Mo and W on the side of the magnetic core half, and x, z, w Is a composition ratio (atomic%)), and is composed mainly of a fine crystalline composition with a crystal grain size of 0.05 μm or less, and the gap side is characterized by Co _x M _z (M is Ti, Zr). , Hf, Nb, Ta, Mo, and W, and x and z are composition ratios (atomic%). The magnetic head is made of an amorphous material. Is disclosed.

Further, in Japanese Patent Application Laid-Open No. 2-229406, "Compositional formula is represented by Co _x M _z C _w , M is Ti, Z
Among r, Hf, Nb, Ta, Mo and W, it is a metal element consisting of one or more kinds or a mixture thereof, and the composition ratios x, z and w are atomic% 55 ≦ x ≦ 96 2 ≦ z ≦ 25 0.1 ≦ w ≦ 20 x + z + w = 100, and the metallographic structure is basically composed of crystal grains with an average grain size of 0.05 μm or less. A soft magnetic alloy film comprising. Is disclosed.

Furthermore, JP-A-3-112104, "compositional formula represented by Co _x M _y C _z, M is Ti, Z
r, Hf, V, Nb, Ta, Mo, W is a metal element consisting of one kind or two or more kinds or a mixture thereof, and the composition ratio x, y, z is atomic% 50 ≦ x <65 15 ≦ y <30 20 <z ≦ 30 x + y + z = 100 is satisfied, and the metal structure is basically composed of crystal grains with an average grain size of 0.05 μm or less, and a crystal phase of the carbide of the element M is partly formed. A soft magnetic alloy film comprising. Is disclosed.

The soft magnetic film or soft magnetic alloy film disclosed in the above publications is at least 5000 G (0.5
T) is a soft magnetic film having a high Bs higher than or equal to T), and is mainly a so-called MIG (metal-in-metal) having a soft magnetic thin film having a Bs higher than that of the core on at least one of the pair of ferrite cores facing the gap portion. -It is intended to be applied to a gap type magnetic head.

Further, JP-A-2-123507 and 2-
The composition disclosed in Japanese Patent No. 229406 partially overlaps with that of the present invention in the claims, but the compositions shown in the examples are out of the scope of the present invention.

Therefore, unlike the present invention, the soft magnetic film or soft magnetic alloy thin film of the composition disclosed in the above publication does not exhibit low Bs, but low Bs of a DGL type or EDG type magnetic head. It is not suitable for use as a soft magnetic thin film and has a configuration different from that of the present invention.

[0024]

Specific Structure The specific structure of the present invention will be described in detail below.

The soft magnetic thin film of the present invention has the following composition.

Co _x M _y C _z

Here, M is Ti, V, Cr, Zr, N
One or more of b, Mo, Hf, Ta, W, and Y, and x, y, and z are composition ratios (atomic%), and have the following relationships.

50 ≦ x ≦ 82, preferably 55 ≦ x ≦ 75 18 ≦ y ≦ 30, preferably 20 ≦ y ≦ 28 0.1 ≦ z ≦ 20, preferably 1.5 ≦ z ≦ 13 x + y + z = 100

By having such a composition,
A low Bs of 45T or less, preferably 0.4T or less can be realized. The lower limit of Bs at this time is not particularly limited,
In terms of magnetic characteristics, it is usually about 0.1T.

Moreover, the coercive force Hc is small, and Hc is 80
A / m or less, preferably 30 A / m or less, and good magnetic properties are obtained. Further, the lower limit of Hc is usually about 0.8 A / m 2.

Further, an appropriate amount of M carbide is formed and Co
Hc can also be prevented from increasing by being present in the grain boundary of the crystal grain containing as a main component and inhibiting the growth of this crystal grain, and the above Hc is realized. The soft magnetic thin film of the present invention is preferably obtained by heat treatment as described below, but the growth inhibition of the crystal grains preferably occurs during the heat treatment.

Further, such growth inhibition of crystal grains is preferable also for obtaining a high magnetic permeability, and an initial magnetic permeability μi of 1000 or more can be obtained at 5 MHz. Further, the upper limit of μi is usually about 5,000. The average grain size of the crystal grains is 50
It is less than or equal to nm, preferably less than or equal to 30 nm, and can be determined from the results of transmission electron microscope (TEM) observation and X-ray diffraction.

From the above, the soft magnetic thin film of the present invention is suitable as a low Bs soft magnetic thin film of an EDG type or DGL type magnetic head.

Further, even if it is repeatedly heat-treated at a high temperature of 500 ° C. or higher, Bs, Hc and μi hardly change, and the heat resistance is excellent. It is considered that this is mainly due to the fact that the presence of the above carbides hinders the growth of crystal grains.

From the above, when the soft magnetic thin film of the present invention is applied to a magnetic head, it is possible to raise the temperature of the glass welding step, and it is possible to use a fused glass having good environment resistance and high strength. Therefore, the yield is improved and the reliability is improved.

Further, even in the production of a composite type magnetic head in which a glass secondary welding step is present, there is little change in magnetic characteristics and sufficient heat resistance is exhibited.

On the other hand, when Co exceeds 82 at%, Bs exceeds 0.45 T, and it becomes impossible to realize low Bs. Further, when Co is less than 50 atomic%, it becomes close to non-magnetic (Bs is zero or a value close to zero at room temperature), or soft magnetism is lost.

Further, even if M exceeds 30 atomic%, it becomes nearly non-magnetic (Bs is zero or a value close to zero at room temperature), or soft magnetism is lost, and M is 1
When it is less than 8 atomic%, Bs exceeds 0.45 T. Furthermore, when C exceeds 20 atomic%, M and Co
The excessive amount of carbides is generated, the coercive force Hc becomes too large, and the soft magnetism is lost. When C is less than 0.1%, the amount of carbide of M produced is insufficient, so the effect of suppressing the growth of crystal grains containing Co as a main component becomes insufficient, and Hc increases. In addition, if the amount of carbide produced is insufficient, the heat resistance will be insufficient.

The values of Bs, Hc and μi in the above are those after the heat treatment which is preferably applied in the present invention. When the thickness of the soft magnetic thin film is 1 μm, Bs is DC and Hc is 50 Hz. μi was obtained at 5 MHz as described above.

In the soft magnetic thin film of the present invention, in the above composition, M is one or more of Zr, Hf, Ti and Y (collectively referred to as M ¹ ), Nb, Mo, Cr, V, and
A combination with at least one of Ta and W (collectively referred to as M ² ) is preferable.

In this case, in the above composition formula, M _y = M
¹ _a M ² _b [where a and b are composition ratios (atomic%), respectively, and y = a + b. ], It is preferable to have a relationship of | a−b | ≦ 10, preferably | a−b | ≦ 8.

By using such a combination, magnetostriction,
In particular, it is possible to reduce the magnetostriction after heat treatment, which is preferably applied as described later, and to obtain high magnetic permeability.

Generally, the magnetic permeability μ is μ = k · (Bs / H
k) [Here, Bs represents a saturation magnetic flux density, Hk represents an anisotropic magnetic field, and k represents a constant. ], It is difficult to obtain high magnetic permeability in the region where Bs is small as in the present invention.

However, since the magnetostriction can be reduced by selecting the composition as described above, high magnetic permeability can be obtained. That is, M ¹ acting to make the magnetostriction constant λs positive and M acting to make it negative.
Magnetostriction can be reduced by combining ² and.

In this case, λs is │λs after the heat treatment (for example, 550 to 700 ° C) which is preferably applied.
| ≦ 5 × 10 ⁻⁷ , which is small.

As a result of the reduction of λs, Bs ≦
Even in the low Bs range of 0.45T, a high magnetic permeability having an initial magnetic permeability μi of 1000 or more at 5 MHz can be obtained.
This μi value is after the heat treatment.

The composition of the soft magnetic thin film is, for example, Elec
It may be measured by the tron Probe Micro Analysis (EPMA) method.

The thickness of the soft magnetic thin film may be appropriately selected according to the application etc., but is usually about 0.1 to 20 μm.

To form the soft magnetic thin film of the present invention, various vapor phase methods such as vapor deposition, sputtering, ion plating and CVD may be used. Of these, it is particularly preferable to use the sputtering method, and for example, the following film formation may be performed.

As the target, an alloy cast body, a sintered body, a multi-source target or the like is used depending on the composition of the soft magnetic thin film.
Then, sputtering is performed in an atmosphere of an inert gas such as Ar. Alternatively, reactive sputtering may be performed in which a target not containing C is used, a hydrocarbon gas such as CH ₄ is mixed in an inert gas such as Ar, and sputtering is performed in this atmosphere.

There is no particular limitation on the method of sputtering and the sputtering apparatus used, and a normal sputtering apparatus may be used. The operating pressure is usually about 0.1 to 1.0 Pa. Various conditions such as the sputtering voltage and the current may be appropriately determined according to the sputtering method and the like.

After the film formation, the soft magnetic thin film is preferably heat-treated.

The heat treatment is preferably performed under the following conditions.

Temperature rising rate: about 2 to 8 ° C./min Holding temperature: 300 to 750 ° C., especially about 500 to 700 ° C. Temperature holding time: about 10 to 60 minutes Cooling rate: 2 to 8 ° C./min

The atmosphere may be an inert gas such as Ar or nitrogen gas.

Further, the heat treatment in the present invention is carried out in the absence of a magnetic field to obtain a sufficient effect. Therefore, it is advantageous in operation as compared with the heat treatment in a static magnetic field or a rotating magnetic field disclosed in, for example, JP-A-2-229406 and JP-A-3-112104.

Although the soft magnetic thin film of the present invention varies depending on the thickness, it is usually formed as an amorphous thin film by sputtering or the like. By subjecting this to heat treatment, C
It is considered that a crystalline phase such as o-M appears and exhibits excellent soft magnetism.

This can be confirmed by the result of X-ray diffraction. That is, by heat treatment, fcc
(Face-centered cubic structure) Co-M (110) plane, (111)
The peaks of the plane, the (531) plane, the (100) plane, and the (533) plane appear. In addition, a peak on the MC (100) plane, which is considered to prevent coarsening of crystal grains such as Co-M, is also confirmed.

The magnetic head of the present invention has the soft magnetic thin film of the present invention, and the soft magnetic thin film of the present invention is formed in the gap portion of the core. Examples of such a magnetic head include EDG type and DGL type magnetic heads, which are used as a low Bs film of such a magnetic head.

An example of the structure of such a magnetic head is shown in FIG.
And FIG. 2 respectively.

The magnetic head shown in FIG. 1 is used as a DGL type magnetic head, and includes a first core 1 having a soft magnetic thin film 4 formed on a surface facing a gap, and a second core.
It has a core 2 and both cores are joined via a gap 5 and are fused and integrated by a fused glass 3.

As the soft magnetic thin film 4, the low Bs soft magnetic thin film of the present invention having a lower Bs than the core is used.

Although the gap 5 is made of a non-magnetic material, it is preferable that the gap 5 is made up of two layers, a gap 51 and a gap 53, as shown in the figure. This will be described later.

The magnetic head shown in FIG. 2 is used as an EDG type magnetic head, and in the configuration of FIG. 1, a soft magnetic thin film 4 is further formed on the surface of the second core 2 facing the gap portion. .

In the configuration of FIG. 2, one soft magnetic thin film 4 is a low Bs soft magnetic thin film of the present invention having a lower Bs than the core, and the other soft magnetic thin film 4 is a Bs soft magnetic thin film having a higher Bs than the core.
In this case, it is preferable to form a low Bs soft magnetic thin film on the first core 1 as in the case of FIG. Also, the high Bs at this time
The soft magnetic thin film 4 is preferably made of a material such as Fe-Al-Si alloy (Sendust) or Fe-Al-Si-Ni alloy (Super Sendust).

In the magnetic head shown in FIGS. 1 and 2, the thickness of the soft magnetic thin film 4 is preferably 0.2-10.
μm, more preferably 0.5 to 5 μm.

When the film thickness of the low Bs soft magnetic thin film of the present invention becomes small, the difference in effective gap length between recording and reproducing becomes too small, and the function as a DGL type or EDG type magnetic head becomes insufficient. . Also, as the film thickness increases,
It is not preferable because the eddy current loss becomes large and the difference in effective gap length between recording and reproducing becomes too large.
On the other hand, when the thickness of the high Bs soft magnetic thin film becomes small,
The volume is insufficient, and saturation easily occurs, and the function of applying a strong magnetic field becomes insufficient. Also, as the film thickness increases, the eddy current loss increases and the high frequency characteristics become insufficient.

In the present invention, each core is preferably made of ferrite. In this case, the ferrite used is not particularly limited, but Mn-Zn ferrite or N is used.
It is preferable to use i-Zn ferrite depending on the purpose. The Mn-Zn ferrite, Fe ₂ O ₃ 50~
It is preferable that about 60 mol%, ZnO 8 to 25 mol%, and the balance substantially MnO. Further, Ni-Zn ferrite exhibits excellent characteristics especially in a high frequency region, and a preferable composition is that Fe ₂ O ₃ is 30 to 30%.
60 mol%, NiO 15-50 mol%, ZnO 5-5
It is about 40 mol%.

The DC saturation magnetic flux density Bs of each core is preferably 0.3 to 0.6T. When the saturation magnetic flux density becomes small, the overwrite characteristic is deteriorated, and in the composition having such a saturation magnetic flux density, the Curie temperature becomes low, so that the thermal stability deteriorates. When the saturation magnetic flux density increases, magnetostriction increases, the characteristics of the magnetic head deteriorate, and magnetization becomes easier.

The initial magnetic permeability μi of each core at direct current is 1.00
The coercive force Hc is preferably 0 or more and 0.3 Oe or less.

It is preferable that the surfaces of the cores facing the gaps are smoothed by mirror polishing or the like so that the soft magnetic thin film 4 and the like can be easily formed.

The gap 5 is, as shown, the gap 5
It is preferable that the layer is composed of two layers of 1 and the gap 53. In this case, it is preferable to use SiO ₂ for the gap 51 and adhesive glass for the gap 53. With the two-layer structure, the gap forming speed and the gap strength can be increased.

The gap 5 is not limited to the example shown in the figure, and the gap 5 may be made of only adhesive glass. Further, in the case of a magnetic head of a type in which a welded glass 3 described later flows into both sides of the gap, the gap 5 is formed. You may comprise only silicon oxide.

The adhesive glass is used for increasing the adhesive strength, and is, for example, Japanese Patent Application No. 1-7150.
The glass shown in No. 6 or the like is suitable.

The method for forming the gap 5 is not particularly limited, but the sputtering method is preferably used. When forming and joining the gap 5, the gap 5 at the joining portion of both cores may be formed and joined to either one of the cores, or may be formed and joined to both cores. The gap length is usually about 0.2 to 2.0 μm. The track width is usually about 3 to 150 μm.

In the present invention, the joining of the cores is usually carried out by thermocompression bonding with the adhesive glass in the gap 53 and at the same time pouring the welded glass 3. The working temperature Tw of the welding glass 3 used is 300 to 750 ° C., and particularly 500 to 7
The temperature is preferably about 00 ° C, and in this case, the holding temperature during glass welding is 300 to 750 ° C, particularly 500 to 70 ° C.
It will be about 0 ° C. In particular, the working temperature Tw of the welded glass 3 used in the glass primary welding step is preferably about 600 to 700 ° C., and the holding temperature during glass welding is 600.
It is preferable to set the temperature to ˜700 ° C. The working temperature Tw
As is well known, is the temperature at which the viscosity of glass becomes 10 ⁴ poise.

The atmosphere at this time is 1 to 100 ppm.
An inert atmosphere containing oxygen may be used.

In the magnetic head of the present invention, since the soft magnetic thin film of the present invention having a high heat resistance is used as the soft magnetic thin film 4 of low Bs, even if the glass having such Tw is used for the welding, the soft magnetic thin film 4 is formed. There is almost no change in Bs, Hc, and μi. For this reason, since a fused glass containing a small amount of lead, alkali metal, etc. can be used, a magnetic head having good environmental resistance and high mechanical strength can be realized.

The soft magnetic thin film of the present invention is preferably subjected to the heat treatment as described above, but since the heating at the time of welding can be substituted for the heat treatment described above, the number of steps can be reduced. .

The magnetic head of the present invention is a so-called laminate type, bulk type, or other tunnel erase type, or a read / write type without an erase head, such as a floppy head for overwriting recording, a monolithic type, or a composite type flying type. It is used as various magnetic heads such as computer heads, rotary VTR heads and R-DAT heads.

[0081]

EXAMPLES The present invention will be described in more detail below by showing specific examples of the present invention.

Example 1 A soft magnetic thin film having a composition shown in Table 1 and a thickness of 1 μm was formed on a crystallized glass substrate by a sputtering method. Sputtering was performed in an Ar atmosphere using a target having a composition corresponding to that shown in Table 1.

The operating pressure was 0.7 Pa. EPMA was used for composition analysis.

The sample prepared in this manner was used as a soft magnetic thin film.
No. 1 to No. 14

Next, these soft magnetic thin films No. 1 to No. 1
4 was heat treated. The heat treatment was performed at 650 ° C. for 1 hour.
The atmosphere was a nitrogen atmosphere containing 10 ppm of oxygen. At this time, a 100 nm thick SiO ₂ film was formed on the soft magnetic thin film.

The soft magnetic thin film No. after the above heat treatment
For 1 to No. 14, the saturation magnetic flux density Bs at DC, 5
Coercive force Hc at 0 Hz, initial permeability μi at 5 MHz
I checked. A VSM was used for Bs measurement, a BH tracer was used for Hc measurement, and an 8-shaped coil permeability measuring device (applied magnetic field 5 mOe) was used for μi measurement. Also, the magnetostriction constant λ
s was determined by an optical lever type saturation magnetostriction measuring machine.

The results are shown in Table 1.

[0088]

[Table 1]

From the results shown in Table 1, the effect of the present invention is clear.

It can be seen that the soft magnetic thin film of the present invention exhibits a low Bs of 0.45 T or less, a small Hc and a large μi, and is excellent in soft magnetism.

Among those shown in Table 1, soft magnetic thin film N
With respect to o.6, the X-ray diffraction measurement was performed on the sample immediately after sputtering and the sample after heat treatment at 650 ° C. for 1 hour.
The results are shown in Fig. 3.

From FIG. 3, it is found that the amorphous state is almost immediately after sputtering, but fcc Co--Zr (1
10) plane, (111) plane, (531) plane, (100)
It can be seen that the peaks of the plane and the (533) plane appear. Further, a peak on the ZrC (100) plane is also observed. Also,
The crystal grain size determined from this was about 24 nm. This value was in agreement with the observation result of the transmission electron microscope (TEM).

From the results of TEM observation and X-ray diffraction, it was confirmed that the crystal grain sizes of the other soft magnetic thin films of the present invention shown in Table 1 were in the range of 5 to 50 nm. .

Further, the soft magnetic thin film of the present invention after the above heat treatment was subjected to heat treatment at 550 ° C. for 1 hour in the same manner as above. The rate of change was within ± 2%, ± 3%, and ± 5%, respectively, and there was no problem at all. From this, it is understood that the soft magnetic thin film of the present invention has excellent heat resistance. Therefore, the composite type magnetic head requiring the second glass welding step can be produced without causing a problem in characteristics.

Example 2 As shown in FIG. 2, F having a soft magnetic thin film 4 on the surfaces of the first core 1 and the second core 2 which face the gap portions, respectively.
An EDG type magnetic head for DD was manufactured. The soft magnetic thin film 4 on the first core 1 side was a low Bs soft magnetic thin film, and the soft magnetic thin film 4 on the second core 2 side was a high Bs soft magnetic thin film.

The soft magnetic thin films shown in Table 1 were used as the low Bs soft magnetic thin films. However, since the heat treatment of the soft magnetic thin film also serves as the heat treatment at the time of glass welding described later, the heat treatment was not performed. The film thickness was 1 μm.

On the other hand, Fe _73.5 Al is used for the high Bs soft magnetic thin film.
_11.0 Si _15.5 alloy film (Sendust: Number is atomic%: Bs
1.1 T, μi = 1500, Hc = 31 A / m 2) was used, and it was formed by the sputtering method according to the low Bs soft magnetic thin film. The film thickness was 2 μm.

The material of each core is Mn-Zn ferrite (B
s = 0.5T, μi = 3000, Hc = 8 A / m).

SiO ₂ was used for the gap 51 and was formed by the sputtering method, and the thickness thereof was 0.2 μm. For the gap 53, adhesive glass having a working temperature Tw of 750 ° C. was used. The gap 53 was formed by the sputtering method, and the thickness thereof was 0.1 μm.

The composition of the fused glass 3 is as follows: SiO ₂ : 22.0, B ₂ O ₃ : 3.0, PbO: 6 by weight.
3.0, Al ₂ O ₃ : 2.0, ZnO: 5.0, Na ₂
O was 5.0, and the working temperature Tw was 640 ° C.
Then, welding was performed at 650 ° C. for 1 hour in a nitrogen atmosphere containing 10 ppm of oxygen.

In this way, an EDG type magnetic head was manufactured. Depending on the low Bs soft magnetic thin film used, the magnetic head N
o. 1 to No. 14 These magnetic heads have a track width of 30 μm and a gap length of 0.3 μm.

The overwrite characteristics (dB) and resolution (%) of these magnetic heads No. 1 to No. 14 were examined as follows.

Recording is performed near the optimum recording current,
The floppy disk used was Hc 1500 Oe.

(1) Overwrite Characteristic: The 1f signal output with respect to the 2f signal output when the 1MHz signal of 1MHz is recorded and then the 2f signal of 2MHz is overwritten thereon. This value is −
The case where it exceeds 30 dB is practically insufficient.

(2) A 1f signal having a resolution of 1 MHz was recorded, and the output of this signal was taken as V _1f . Separately, a 2 MHz 2f signal was recorded, and this output was taken as V _2f . From these, the resolution was calculated by the following formula.

Formula (V _2f / V _1f ) × 100 [%]

If the resolution is less than 60%, it is not practical.

The results are shown in Table 2.

[0109]

[Table 2]

From Table 2, the effect of the present invention is clear.
The magnetic head of the present invention has excellent overwrite characteristics and good resolution.

Further, the EDG type magnetic head of the present invention has a yield improved by 10% or more as compared with the magnetic head using the conventional fused glass having a working temperature Tw of 550 ° C. or less.

Also, when the soft magnetic thin film of the present invention is used as a low Bs soft magnetic thin film of a DGL type magnetic head, good characteristics can be obtained as in the above EDG type magnetic head, and the yield is improved. did.

[0113]

The soft magnetic thin film of the present invention has low Bs and excellent heat resistance. Therefore, it is suitable for use as a low Bs soft magnetic thin film of an EDG type or DGL type magnetic head. Further, the holding temperature at the time of glass welding in manufacturing the magnetic head, particularly the holding temperature at the time of primary welding can be increased to 600 ° C. or higher. Therefore, a fused glass having good environment resistance and high mechanical strength can be used, and a magnetic head with high reliability and high manufacturing yield can be realized.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a configuration example of a magnetic head of the present invention.

FIG. 2 is a partial cross-sectional view showing a structural example of a magnetic head of the present invention.

FIG. 3 shows X immediately after sputtering the soft magnetic thin film of the present invention.
It is a line diffraction chart and an X-ray diffraction chart after heat treatment.

[Explanation of symbols]

 1 1st core 2 2nd core 3 Welding glass 4 Soft magnetic thin film 41 Underlayer film 5, 51, 53 Gap

Claims (5)

[Claims] 1. Co _x M _y C _z [where M is Ti,
V, Cr, Zr, Nb, Mo, Hf, Ta, W and Y
And x, y, and z are composition ratios (atomic%), respectively. ], X, y, and z have a relationship of 50 ≦ x ≦ 82 18 ≦ y ≦ 30 0.1 ≦ z ≦ 20 x + y + z = 100, and a saturation magnetic flux density Bs is 0. A soft magnetic thin film of 45T or less. 2. The M is a combination of at least one of Zr, Hf, Ti and Y and at least one of Nb, Mo, Cr, V, Ta and W. Soft magnetic thin film. 3. Co _x M ¹ _a M ² _b C _z [where M ¹ is Z
at least one of r, Hf, Ti and Y, and M ²
Is one or more of Nb, Mo, Cr, V, Ta and W, and x, a, b and z are composition ratios (atomic%), respectively. ], And x, a, b
The soft magnetic thin film according to claim 1, wherein z and z have a relationship of 50 ≦ x ≦ 82 18 ≦ a + b ≦ 30 | a−b | ≦ 10 0.1 ≦ z ≦ 20 x + a + b + z = 100. 4. After forming a thin film having the composition,
It was obtained by heat treatment at a temperature of 300 to 750 ° C.
The soft magnetic thin film according to any one of 1 to 3. 5. A magnetic head having the soft magnetic thin film according to claim 1.