JPH0536027A - Thin-film head - Google Patents

Abstract

PURPOSE:To obtain the thin-film head adequate when used for a magnetic recording medium of a high linear recording density by decreasing the influence of the undershoot generated by the shape effect of a thin-film core on signal reproducing output. CONSTITUTION:This thin-film head is constituted by forming a step part 21 which reduces the thickness at both side ends in the track width direction of a magnetic gap g on the thin-film core 20 facing a surface 30S in contact with or facing the magnetic recording medium.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film head mounted on a slider or the like of a hard disk drive for recording and reproducing.

[0001]

2. Description of the Related Art FIG. 5 shows an enlarged schematic front view of an example of a conventional thin film head as seen from the magnetic gap side. In FIG. 5, reference numeral 1 denotes a base made of a non-magnetic material, on which a lower core 12 made of a magnetic layer, a non-magnetic layer 4 forming a magnetic gap g in the front, and an upper core 13 made of a magnetic layer have a required pattern. And a protective layer 10 made of a non-magnetic layer is entirely covered so as to cover them. In this case, the thin film cores 12 and 13 are formed to have substantially the same width in the track width direction.

A method of manufacturing an example of such a thin film core will be described with reference to the manufacturing process diagrams of FIGS. in this case,
First, as shown in FIG. 6A, a first lower layer core 2 made of a magnetic layer is adhered and formed on a substrate 1 made of a non-magnetic material, and a magnetic layer is formed on a portion of the first lower core 2 which is separated from a magnetic gap g described later. A second lower core 3 consisting of is deposited.

Next, as shown in FIG. 6B, a nonmagnetic layer 4 forming a magnetic gap g is deposited on the second lower core 3 and an insulating layer 5 made of a nonmagnetic layer is entirely formed. To form a winding coil 6 by patterning after applying a conductive layer thereon.

Further, as shown in FIG. 6C, the insulating layer 7 is further added.
Is deposited so as to fill the space between the coils 6, and then the insulating layers 7 and 5 are tapered to expose the nonmagnetic layer 4 of the magnetic gap g forming portion, while the lower core 3 is formed. The rear part, which will be a connecting part with the upper core, which will be described later, is exposed.

Next, as shown in FIG. 6D, a first upper-layer core 8 made of a magnetic layer is deposited so as to fill the exposed portion, and the first upper-layer core 8 and the first upper-layer core 8 are attached at the tip end thereof. A magnetic gap g is formed by sandwiching the non-magnetic layer 4 with the lower core 2 of 1. Then, a second upper layer core 9 is formed on the layer except the portion forming the magnetic gap g, and a non-magnetic protective layer 10 is deposited so as to cover them, and then the front is polished. The surface 30S facing the recording medium facing the magnetic gap g is formed to obtain a thin film head.

As described above, in the conventional thin film head, the film thickness of each core 2 and 8 in the portion forming the magnetic gap g is made smaller than that in the rear portion to increase the magnetic flux density, and in the rear portion, A structure is adopted in which the magnetic resistance is reduced by increasing the film thickness, and each upper layer core and lower layer core has 2 layers.
It is formed as a layered structure.

FIG. 7 shows an isolated waveform of the reproduction output by such a thin film head. In FIG. 7, m is a main peak indicating the signal output, and the undershoot parts u ₁ and u _{2 on} both sides of this are smaller in peak value than the main peak m.
Occurs. Such an undershoot portion is due to a so-called shape effect generated by the shape of the thin film head, and is caused by the width of each thin film core, that is, a so-called pole length.

On the other hand, in recent years, in order to increase the recording density of magnetic recording media, the linear density of recording tracks has been improved. Therefore, for example, when positive and negative signals are recorded close to each other on adjacent tracks, there is a problem in that the undershoot portion causes interference with the main peak of another adjacent portion, resulting in peak shift of the signal output. there were. In order to avoid such peak shift, it is necessary to make the difference between the reproduction output value of the main peak and the reproduction output value of the undershoot portion large.

Therefore, as a method of suppressing the above-mentioned shape effect, it is conceivable to make the thickness of the thin film core in the gap length direction smaller than the recording wavelength, but at present, such a small thickness is used. However, a magnetic material that obtains a sufficient amount of magnetic flux has not been obtained. In the case where the distribution of the distance from the magnetic gap g to the end of the magnetic core is not made constant, and the thickness is gradually varied from the end to the center in the track width direction, the thickness is gradually reduced. For example, although not shown, ideally, when the upper and lower thin film cores have semicircular cross-sections facing each other and the chords are butted to form the magnetic gap g, the above-described shape effect is suppressed. However, it is technically and economically difficult to obtain such a structure.

[0010]

The present invention reduces the influence of the undershoot generated by the shape effect of the thin film core on the signal reproduction output, and is suitable for use in a high linear density magnetic recording medium. The purpose is to obtain a thin film head.

[0011]

FIG. 1 is an enlarged schematic front view of an example of a thin film head according to the present invention as viewed from the magnetic gap g side. According to the present invention, as shown in FIG. 1, a thin film core 20 facing a surface 30S facing or facing a magnetic recording medium.
In addition, the step portion 21 is formed by thinning both ends of the magnetic gap g in the track width direction.

[0012]

As described above, in the thin film head of the present invention,
The thin film core 20 is formed with the stepped portions 21 whose both ends in the track width direction are thin. With such a configuration, the influence of the reproduction output waveform on the signal reproduction output of the undershoot portion is affected. It was possible to reduce.

As an example, as shown in FIG. 1, the thin film core 2
0 lower layer core and upper layer core each have a two-layer structure
The upper and lower first and second upper and lower core layers, respectively.
When the step portion 21 is formed between the cores 2 and 3, 8 and 9
Will be described. At this time, the isolated waveform of the playback output is
As shown in FIG. 2, at the interface between the base 1 and the first lower core 2,
Undershoot part u_a1, Insulating layer 11 and second lower layer
Undershoot portion u due to the interface with the core 3_a2, First
Undershoe due to the interface between the upper core 8 and the protective layer 10
Part u_b1, Due to the interface between the second upper core 9 and the protective layer 10.
Undershoot part u_b2And occur. This under
Shoot part u_a1, U_a2, U_b1, U_b2Is, for example, in FIG.
As described above, the head of the conventional structure with no step is provided.
Compared to the undershoot portion of the playback waveform at
Each has a small peak value, and the peak of the main peak m
Value E_mEach undershoot part u against_a1, U_a2,
u _b1, U_b2Peak value E_a1, E_a2, E_b1, E_b2The ratio of
I was able to make each small.

By thus dispersing the thickness of the thin film core in the gap length direction, the undershoot portions can be dispersed, and as a result, the peak value of each undershoot portion can be reduced.

Therefore, even in a magnetic recording medium having a high linear recording density, the influence of the undershoot portion on the signal output due to the interference of the main peak of the reproduction output waveform of another adjacent track. Can be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the thin film head of the present invention will now be described with reference to FIGS. 1, 2 and 3A to 3D, and FIG. 4 showing a schematic enlarged front view of the essential part of one manufacturing process. The details will be described.

In this case, step portions 21 are formed above and below the thin film core 20.
In this example, one layer is formed on each side, and each of the upper and lower cores has a two-layer structure.
The lower core 2 and the second lower core 3 are adhered and formed, and the first upper core 8 and the second upper core 9 are adhered and formed thereon with the non-magnetic layer 4 interposed therebetween. The thin film head 30 of the present invention is formed by covering and covering the entire surface with the protective layer 10. Reference numeral 30S is a surface facing or facing the magnetic recording medium.

In particular, in the present invention, the width of the first lower core 2 and the second upper core 9 in the track width direction is L ₁ at least on the facing surface 30S, and the cores 2 and 9 are in the track width direction. The second lower layer core 3 and the first upper layer core 8 are formed so as to have a width L ₂ and a width L ₃ on both sides thereof. That is, the width of each layer in the track width direction is set to L ₁ which is relatively narrow in the outer first lower layer core 2 and the second upper layer core 9, and is set to the inner second lower layer core 3 and the first upper layer core 9. In _No. 8, it is configured as a relatively wide (L ₁ + L ₂ + L ₃ ).

An example of a method of manufacturing such a thin film head will be described with reference to FIGS. First, as shown in FIG. 3A, a first magnetic layer is formed on a base 1 made of a non-magnetic material.
The lower core 2 is formed by frame plating or the like,
The flattening film 11 made of a non-magnetic layer is, for example, entirely deposited so as to surround the periphery of the first lower core 2, and then a required portion is removed by etching to form the lower core 2.
Flatten the upper surface of. Then, a second lower core layer 3 made of a magnetic layer is adhered and formed on this flat surface.

FIG. 4 shows an enlarged schematic sectional view taken along the line AA in this step. In this case, as shown in FIG.
Compared with the width L ₁ of the first lower layer core 2 in the track width direction,
The width of the second lower-layer core 3 is made large, and both ends of the second lower-layer core ₃ project from both ends of the first lower-layer core 2 with widths L _{2 and} L _{3 ,} respectively.

Next, as shown in FIG. 3B, a nonmagnetic layer 4 forming a magnetic gap g is deposited on the second lower core 3 and an insulating layer 5 made of a nonmagnetic layer is entirely covered. The wire-wound coil 6 is formed by depositing and flattening, depositing a conductive layer on this, and then patterning.

Further, as shown in FIG. 3C, an insulating layer 7 is further added.
Is deposited so as to fill the space between the coils 6, and then the insulating layers 7 and 5 are subjected to taper etching to expose the nonmagnetic layer 4 in the magnetic gap g forming portion, while the lower core 3 A rear part, which is a connecting part with an upper layer core described later, is exposed.

Next, as shown in FIG. 3D, a first upper layer core 8 made of a magnetic layer is applied so as to fill the exposed portion, and the first upper layer core 8 and the first upper layer core 8 are attached at the tip end thereof. A magnetic gap g is formed by sandwiching the non-magnetic layer 4 with the lower core 1 of FIG. Then, a second upper layer core 9 is further deposited on this, a nonmagnetic protective layer 10 is deposited so as to cover them, and the front of the magnetic gap g is further polished to form a magnetic recording medium. The thin film head is obtained by forming the facing or facing surface 30S.

In the sectional view taken along the line BB at this time, the second upper core 9 has a smaller width in the track width direction than the first upper core 8 as in the front view of FIG. The configuration is formed as. In this way, the step portions 21 are formed on both sides of the first and second lower layer cores 2 and 3 in the track width direction, and similarly, on both sides of the first and second upper layer cores 8 and 9 in the track width direction. The step portion 21 is formed. That is, in this case, the thin film core 20 is configured to be thin on both sides in the track width direction.

FIG. 2 shows an isolated waveform of the reproduction output when the step portion 21 is provided by forming the upper core and the lower core in two stages as described above. In this case, two undershoot parts u _a1 , u _a2 and u _b1 , u _b2 are shown on each side of the main peak m. That is, the step 21
By providing, the undershoot portion is dispersed.

In order to reduce the peak value of the undershoot portion, it is desirable to disperse them evenly. In this embodiment, the width of each of the above cores is given by
It was selected and constructed as shown in.

[0027]

[Equation 1] 0.7 <(L ₂ + L ₃ ) / L ₁ <1.3

With such a configuration, each
Undershoot part u_a1, U_a2, U_b1, U_b2Peak value E
_a1, E_a2, E_b1, E_b2Can be reduced respectively
It was That is, in this embodiment, all undershoot parts
Regarding the peak value of the undershoot part,
The peak value ratio of the signal output is higher than that of the conventional thin film head.
And became big. In the above-mentioned conventional example and the above-mentioned embodiment,
Each core has a symmetrical structure with a magnetic gap g in between.
The thicknesses of 2 and 3, 8 and 9 are made equal, and the gap of each layer is
Width in the track width direction in the top part
If the lengths are set equal, then the under
-The peak values in the shoot are almost equal. Figure 7 Smell
Undershoot part by the conventional thin film head described above
u_a, U _bThe peak value of_a, E_bThen, E_a= E
_bAnd the undershoot of this embodiment
The peak value of each part is E_a1= E_b2, E_a2= E_b1Tona
It Here, the peak value of the main peak of the conventional example is E_m1,Book
The peak value of the main peak in the example is E_m2To
Then, in this case, the following expressions 2 and 3 are established.

[0029]

[ _Equation 2] E _m1 / E _a <E _m2 / E _a1

[0030]

[ _Equation 3] E _m1 / E _a <E _m2 / E _a2

In the above example, the output difference between the peak value of the signal output and the peak value of the undershoot portion can be set to about 24 dB to 26 dB. By obtaining such an output difference, it was possible to reduce the peak shift due to the interference of the reproduced output waveform to the extent that it is not a practical problem. Further, in this case, the half width of each undershoot portion becomes large, and the influence on other main peaks can be made smaller.

Therefore, when reproducing a high linear density recording medium using the thin film head of the present invention, interference of signal output due to the undershoot portion can be suppressed, peak shift of reproduced waveform can be reduced, and stable. Playback can be performed.

In the above example, the width of each core is selected to be in the range shown in the above formula 1, but when the range shown in this formula 1 is configured to exceed the width of each core, it is as described above. Two
It is difficult to obtain a reproduction output difference of about 4 dB to 26 dB. Therefore, in the present invention, it is desirable to select the width of each core within the range shown by the above-mentioned formula 1.

Further, in the above-described present embodiment, the film thickness of each core 2 and 8 in the portion forming the conventional magnetic gap g is made smaller than that in the rear portion to increase the magnetic flux density and the rear portion. 2), a thin-film head having a two-layer structure in which the film thickness is increased to reduce the magnetic resistance could be manufactured without increasing the number of steps.

In the above-described embodiment, the upper and lower thin film cores each have a two-layer structure. However, in other cases, for example, a three-layer structure, the step portion is provided with two steps on both sides in the track width direction. In various cases, various configurations can be adopted.

However, when the above-mentioned three-layer structure thin film core is manufactured, the manufacturing process may be complicated. On the other hand, when the above-mentioned upper and lower layer cores are respectively formed as the two-layer structure, As described above, it has an advantage that it can be easily manufactured with almost no increase in the number of steps as compared with the conventional thin film head.

In the above embodiment, the thickness of each thin film core and the pole length are set to be equal, and the magnetic gap g
Although the configuration is symmetric with respect to each other, the film thickness and the pole length may be changed to have an asymmetric configuration.

[0038]

As described above, according to the thin film head of the present invention, the surface 30S facing or facing the magnetic recording medium.
The thin film core 20 is formed so that the thickness of the thin film core 20 facing each other becomes thin on both sides of the magnetic gap g in the track width direction.
The distance between the interface with the non-magnetic layer and the magnetic gap g can be varied, the peak value of the undershoot portion can be reduced, and the full width at half maximum can be increased to affect the undershoot portion to the main peak. Can be suppressed.

Therefore, even when the recording medium having a high linear recording density is reproduced, the interference of the undershoot portion of the signal reproduction output between the adjacent tracks is suppressed, the peak shift of the reproduction waveform is reduced, and the reproduction output is reduced. The characteristics can be improved.

Furthermore, when the upper and lower layer cores of the thin film core 20 are each formed into a two-layer structure to form the step portion 21, the step portion 21 can be formed without increasing the number of manufacturing steps as compared with the conventional thin film head. And can be easily manufactured.

[Brief description of drawings]

FIG. 1 is an enlarged schematic front view of a main part of an example of a thin film head of the present invention.

FIG. 2 is a diagram showing reproduction output characteristics of an example of the thin film head of the present invention.

FIG. 3 is a manufacturing process diagram of an example of the thin film head of the present invention.

FIG. 4 is an enlarged schematic cross-sectional view of a manufacturing process of an example of the thin film head of the present invention.

FIG. 5 is a schematic linear enlarged front view of a main part of an example of a conventional thin film head.

FIG. 6 is a manufacturing process diagram of an example of a conventional thin film head.

FIG. 7 is a diagram showing reproduction output characteristics of an example of a conventional thin film head.

[Explanation of symbols]

 1 Base 2 First Lower Layer Core 3 Second Lower Layer Core 4 Nonmagnetic Layer 5 Insulating Layer 6 Coil 7 Insulating Layer 8 First Upper Layer Core 9 Second Upper Layer Core 10 Protective Layer 11 Flattening Film 12 Lower Layer Core 13 Upper Layer Core 20 Thin film core 21 Step portion 30 Thin film head 30S Facing surface

Claims (1)

Claim: What is claimed is: 1. A thin film core facing a surface facing or facing a magnetic recording medium is provided with a step portion having thinned both ends in the track width direction of the magnetic gap. Characteristic thin film head.