JPS61255514A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To attain the high sensitivity of a thin film magnetic head by forming gaps with use of through holes after forming lower cores divided for each track and cutting away a part of the lower cores excluding the areas near the gaps to form a contraction in the width direction of the gap. CONSTITUTION:The grooves 1a and 1b are formed at positions corresponding to the recording track on a nonmagnetic substrate 1 with the width larger than those of tracks. The lower cores 12a and 12b are buried into the grooves 1a and 1b respectively. A gap material 11 is provided on the substrate 1 to control the gap length. Then an insulated layer 13 is formed on the surface of the material 11 with through holes 13a and 13b formed for control of the track width. The upper cores 10a and 10b are provided opposite to the cores 13a and 13b via the material 11 within the holes 13a and 13b formed on the layer 13. The cores 12a and 12b have widths larger than those of tracks and at the same time the gaps 11a and 11b are formed by cutting the cores 12a and 12b adjacent to the tracks at the side where the cores 10a and 10b are not formed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a thin film magnetic head suitable for recording and reproducing analog signals. Regarding magnetic heads.

[Background of the invention]

As a conventionally known thin film magnetic head, for example, there is a multi-element thin film magnetic head described in Japanese Patent Laid-Open No. 58-212616. This magnetic head has a common lower core, and the lower core part is flat, making wafer processing easy. However, since there is a common lower core under adjacent tracks, , there is a problem of increased crosstalk. This crosstalk is
Approximately 30 dB is allowed in digital magnetic recording, and the above configuration can fully satisfy this requirement, but for recording and reproducing analog signals such as video, 40 dB is allowed.
These requirements cannot be fully satisfied with a configuration in which the lower core is shared and the wafer process is simplified.

Also, in order to achieve high sensitivity, it is desirable to make the width of the rear core larger than the track width. The magnetic recording medium sliding forming line portion of the lower core between the magnetic recording media generates a pseudo gap and reads signals from adjacent recording tracks other than the intended one, resulting in poor crosstalk.

As described above, in the multi-element thin film magnetic head, it is difficult to achieve both low crosstalk and high sensitivity.

From the above, it can be easily inferred that in order to reduce crosstalk, it is effective to divide the commonly formed lower core into individual tracks. Therefore, in order to separate the lower core on the premise that a wafer process is employed, a method using buttering is suitable from the viewpoint of manufacturing accuracy.

In order to obtain a multi-element thin film magnetic head with a structure in which the lower core is separated, for example, a thin film magnetic head with a structure in which the lower core is patterned as disclosed in Japanese Patent Application Laid-Open No. 50-67122 is placed on the same substrate. You only need to make multiple pieces.

However, in the multi-element thin film magnetic head manufactured as disclosed in the above publication, when the core layer is thickened for the purpose of reducing magnetic resistance in order to increase sensitivity (1), for example, the upper core thickness is 30 μm, the lower core thickness is 30 μm, Track width 5
0 μm,) When the rack pitch is 100 μm, the width of track width patterning is 50 μm, and the patterning depth is 3.
It becomes 0 μm.

When the patterning depth is deep relative to the patterning width as described above, there is a problem in that the influence of the side edges becomes large, making it impossible to perform patterning with high precision. However, even with the thin film magnetic head described in the above publication, it is difficult to achieve both low crosstalk and high sensitivity.

Another possible method is to form grooves with a predetermined track width and core thickness in the substrate using a cutting tool, wire saw, or the like. In this method, it is difficult to deposit a magnetic film by sputtering, vapor deposition, etc. on the bottom of a deep groove formed in the substrate, so it is quite difficult to embed the lower core in the substrate and separate it.

As described above, in order to obtain a multi-element thin film magnetic head suitable for recording and reproducing analog signals, it is necessary to simultaneously solve the contradictory problems of low crosstalk and high sensitivity.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art as described above, and its purpose is to facilitate the wafer process,
It is an object of the present invention to provide a thin film magnetic head suitable for recording and reproducing analog signals that is capable of reducing crosstalk and has high sensitivity.

[Summary of the invention]

From this point of view, the present invention forms a groove wider than the track width for embedding the lower core at a position corresponding to the recording track on the nonmagnetic substrate, and further forms the lower core within this groove. After forming the lower core, a gap material for regulating the gap length is provided on the lower core and the substrate, an insulating layer in which a through hole is formed is further provided on the gap material, and then an insulating layer is provided on the gap material. A predetermined upper core is formed in the through hole and on the insulating layer, and the gap width and gap depth are defined by the opening on the lower coil side of the through hole.
Furthermore, a protective layer is formed on the upper core and the insulating layer, and a protective plate is attached on this protective layer via an adhesive layer.The sliding surface of the magnetic head formed using thin film technology in this way is The side is wider than the track width, and at least the side where the upper core is not adjacent is cut out, and this cut position is a position where the lower core does not overlap the adjacent track in terms of the cut side pressure. According to this configuration, the lower core is embedded in the substrate for each track (including the case of a single track) and is separated, and the lower core with a thick core layer does not impair the magnetic properties of the substrate. In order to be able to embed the lower core without any gaps, the width of the groove for the lower core was made sufficiently wider than the desired track width, and the width of the groove was widened so that there was no sliding formation line other than the gap in the lower core. The part becomes a pseudo gap to read the signal of the adjacent recording track that is not the target of reproduction, and at the same time avoids deterioration of crosstalk caused by reading the signal of the adjacent recording track, and at the same time squeezes the lower core. It is characterized by removing unnecessary parts to increase the density of the structure.

In addition, in order to solve the problem of deterioration in patterning accuracy caused by increasing the lower core thickness and upper core thickness to increase sensitivity, we created a through hole with the same width as the track width in the nonmagnetic layer above the lower core. By drilling an upper core and forming an upper core on top of it, highly accurate track width regulation can be achieved using the opening on the gap material side of the through hole.Furthermore, by patterning the upper core on the outside of the through hole, difficult slope areas can be controlled. In addition to avoiding patterning, the cross-sectional shape of the opening at the slope of the through hole is reduced toward the lower core side, creating a narrowing structure in the core thickness direction, resulting in higher density. There is also.

[Embodiments of the invention]

An example of the implementation of the present invention will be explained below based on the drawings.

1 to 8 are for explaining the multi-element thin-film magnetic head according to the present embodiment, and FIG. 1 is a perspective view showing the sliding surface of the magnetic recording medium of the multi-element thin-film magnetic head, and FIG. 3 is a front view showing one chip of a multi-element thin-film magnetic head, FIG. 3 is a perspective view schematically showing the wafer state of the multi-element thin-film magnetic head, and FIG. 4 is a perspective view showing a state in which a protection plate is formed on the upper core side. Fig. 5 is a perspective view showing the state in which the sliding surface has been polished and processed, Fig. 6 is a perspective view showing the state in which the lower core other than the gear lug portion has been removed, and Fig. 7 is a perspective view showing the state in which the sliding surface has been processed by grinding. FIG. 8 is a perspective view showing a state in which the side portions are further removed from the state shown in the figure, and FIG. 8 is a perspective view showing -fFIJ in a used state of the formed magnetic head.

The details of the multi-element thin film magnetic head shown in FIGS. 1 to 8 will be explained following the manufacturing process.

First, grooves 1a and lb for embedding the lower core are separated for each track on the surface of one side of a non-magnetic substrate 1 made of glass, ceramics, ferrite, etc. using a dicing machine, a wire cutting machine, an ultrasonic processing machine, etc. Form. Since the grooves 1a and lb are two tracks in this embodiment, two grooves are cut per chip 1c. The depth of the gulfs 1a and lb is 40 μm, taking into account a core thickness of 30 μm and a lap margin of 10 μm, and the groove width is set to a track width of 50 μm. In consideration of coverage and aperture structure, the width is set to 300 μm, which is wider than the track width.

After the grooves 1a and lb are formed on the substrate 1, the next step K.

A core material such as sendust or amorphous is formed in the grooves 1a and 1b to a thickness of approximately 40 μm by sputtering, vapor deposition, etc., and then flattened by lapping or the like to form a lower core 12a having a core thickness of 30 μm.

12b was formed.

Next, metal chromium is sputtered or vaporized to a thickness of 0.3 μm as a gap II material on the lapped surface.
A gap lla is formed to a thickness of .

11b was obtained, and 2μ of silicon dioxide was further added as an insulating layer.
Copper is deposited to a thickness of m and patterned by sputtering or vapor depositing copper on top.
A coil of m thickness is formed. Then, from above, silicon dioxide, which is the same as the insulating layer described above, is deposited to a thickness of 4 μm to form an insulating layer 13 having a thickness of 6 μm and containing the coil at a predetermined location.

After the insulating layer 13 is formed, through holes 13a and 13b of a predetermined shape are formed by ion milling or wet etching at predetermined positions of the insulating layer 13 that can face the lower cores 12a and 12b. When through holes 13a and 13b are formed, this through hole 13
A core material of the same material as the lower core is sputtered or vapor-deposited and patterned inside 1.3b and on the insulating layer 13 to form an upper core 10a and a lob having a thickness of 30 μm.

Furthermore, the formed upper cores 10a and 10b and the insulating layer 1
3, an insulating material such as forsterite or alumina is deposited to form a protective film 9 with a thickness of 60 μm. In this manner, a multi-element thin film magnetic head as shown in FIG. 3 is obtained in the form of a wafer. In this process, the track width is restricted to the upper core 10a*lob and the lower cores 12a, 12.
Through holes 13a, 1 bored in the insulating layer 13 between b
3b with extremely high precision, and the through hole l 3 a e 13 b has a gap lla
.

Since the opening area is inclined so that it becomes smaller toward 11 b@, the cross-sectional area in the core thickness direction decreases toward the gap side, making it possible to increase the magnetic flux density.

The wafer on which a large number of multi-element thin film magnetic heads are formed as described above is mechanically cut, for example, along the line A-A shown in FIG. Get something in the form of a strip. A protective plate 2 made of the same material as the substrate 1 is placed on the protective film 9 of the multi-element thin film magnetic head formed in the form of a large number of strips, as shown in FIG. The adhesive layer 8 is bonded to the adhesive layer 8 made of resin or glass, and then K as shown in FIG.

The sliding surface is made parallel and mirror-finished by cylindrical grinding, surface grinding, etc., and a predetermined gap depth is obtained.
Since the parallelism of the sliding surface can be achieved within about 30 seconds, after the sliding surface processing described above, machining of 2"C or less can be performed by using this sliding surface as the reference surface for processing. , which can be used for mass production.

After this sliding surface processing, as shown in Figs. 4 and 6, using a dicing saw, wire saw, ultrasonic processing machine, etc.
The lower cores 12a, 12b on the side where the upper core log, 10b is not adjacent are set to a width wider than the gap width and to a depth of 10 to 3 so that they do not overlap with adjacent recording tracks.
Grooves 15a and 15b are formed by cutting at 0 μm. And more.

Grooves 16a, 16b are formed by cutting the outside of the gulfs 15a, 15b using a dicing saw, wire saw, ultrasonic processing machine, or the like. The former lower core 12a.

Groove 15a, 1 formed by removing a part of 12b
In the multi-element magnetic head having the structure of this embodiment, the width of the lower core 12at12b is wider than the width of the upper cores 10a and 10b.
Since the width of the lower core 12a is wider, the width of the lower core 12a is wider.
, 12b gap lla, the line portion on the sliding surface other than the 11b portion becomes a pseudo gap, which is formed for the purpose of preventing signals from unintended recording tracks on the magnetic recording medium from being reproduced. , ko (7) grooves 15a, 15b
By forming.

In addition to obtaining a crosstalk of 40 dB or more that is allowable in an analog signal recording and reproducing system, the lower cores 12a, 1
2b has a restriction in the track width direction. latter groove 1
6a and 16b are formed for the purpose of improving sliding properties. And these grooves 15a, 15b, 16a,
After forming the Teg 16b, each Teg lc is cut out, bonded to the head base 3 with resin or adhesive, and wired to obtain a multi-element thin film head according to an embodiment of the present invention. In addition, in the multi-element thin film head structure described above, when the number of coil windings is small and the output is small, efficient recording and reproduction can be performed by connecting a step-up transformer to 5 as shown in FIG. They are connected to the magnetic wrap transformers 4a and 4b shown in FIG. 8, respectively, and the output therefrom is further transmitted from the secondary coils of the step-up transformers 4a and 4b to the amplifier side.

In this embodiment with the above-mentioned 5rIc configuration, since the lower cores 12a and 12b are separated between adjacent tracks, compared to the conventional structure in which the lower cores are continuous, it is possible to sufficiently support analog recording. Crosstalk has been improved, and since the track width is regulated by the through holes 13a and 13b opened in the insulating layer 13VC, the accuracy of the track width is as high as the gaps lla and l of the cores 12a and 12b.
Since a portion other than the vicinity of the lb portion is removed, the width accuracy of the grooves 1a and 1b for embedding the lower core is not required so much.

There are effects such as the ability to easily cut @la and lb grooves on the substrate 1.

Next, the control of the gap depth used to polish the sliding surface, ie, the method used to polish the sliding surface to a predetermined gap depth, will be described. This example is the ninth
This is shown in Figures 1 to 12.

This gap depth control is achieved by forming a marker 17 in the through hole 13a with a material different from that of the insulating layer 13, whose gap depth corresponds one-to-one to the cross-sectional length on the sliding surface side, as shown in FIG. , provided around the gear part between 13b,
This is done by observing the length of the cross section of the marker 17 from the sliding surface. Examples to which this is applied are shown in Figures 11 and @12. In FIG. 11, the marker 14 is connected to the through hole 13.
a.

In this example, the gap material 11.13b is formed on the sliding surface. Marker 17 and insulating layer 13 appear to overlap. For this reason.

It is easier to recognize the marker 17 if the material is different from the insulating layer 13 as well as from the gap material 11. FIG. 12 shows an example in which the marker 14 is formed on the same surface as the gear material 11 forming surface, by forming the gap material 11 and the marker 14 separately.

It is also possible to form the marker 14 with the same material as the gap material 11.

In addition, for example, during mass production, a plurality of markers 19 having elongated shapes with different lengths are provided in parallel to the gap depth direction as shown in Fig. 1O, and the gap depth is determined by the number of markers 19 appearing on the sliding surface during polishing. It can also be configured as 5. In this way, the gap depth can be determined by measuring the length of the marker 19 (without measuring the length of the marker 19), so gap control becomes extremely easy and productivity is improved. The dotted line indicated by 18 in FIG. 10 indicates the position where the lower cores 12a, 12b begin to be squeezed.

When polishing a sliding surface with such markers 17 and 19 provided, by observing only the sliding surface during the polishing process, information such as the gap depth necessary for processing the sliding surface can be obtained. Since the entire process can be completed, it is possible to improve the efficiency of assembling the multi-element thin film magnetic head.

〔Effect of the invention〕

As described above, according to the present invention, the lower core is divided into each track, a gap is formed using through holes, and then a part of the lower core is removed, leaving the vicinity of this gap. By forming a restriction in the width direction of the gap, we provide a thin film magnetic head that is suitable for recording and reproducing analog signals, which facilitates the Ueno process, achieves high sensitivity, provides good tracking accuracy, and reduces crosstalk. can do.

[Brief explanation of the drawing]

1 to 8 are for explaining one embodiment of the present invention. FIG. 1 is a perspective view showing a sliding surface of a magnetic recording medium of a multi-element thin film magnetic head, and FIG. 2 is a multi-element thin film magnetic head. 3 is a perspective view schematically showing the state of a wafer of a multi-element thin film magnetic head; FIG. 4 is a perspective view showing a state in which a protection plate is formed on the upper core side; FIG. The figure is a perspective view showing a state in which the sliding surface has been polished, and FIG. 6 is a perspective view showing a state in which the lower core has been removed leaving a gap portion. 7 is a perspective view showing a state in which the side 4p is further removed from the state shown in FIG. 6, FIG. 8 is a perspective view showing an example of the state in which the formed thin film magnetic head is used, and FIGS. 9 to 12 are 9 is a plan view showing an example of a marker having a shape that makes a one-to-one correspondence between the gap depth and the width of the marker, and FIG. 10 is a plan view showing a number of markers of different lengths. FIG. 11 is a plan view showing an example in which a marker is provided, FIG. 11 is a perspective view showing an example in which a marker is provided on the insulating layer side of the gap material, and FIG. 12 is a perspective view showing an example in which a marker is provided at the position of the gap material. l...Substrate, la, lb...groove, 2.
...Protection plate, 3...Head base, 8.
...Adhesive layer, 9...Protection plate, 10a, l
Ob... Upper core, 11... Gap material, lla, llb... Gap, 12a. 12b...lower core, 13a, 13b...
・Through hole, 15a, 15b, 16a, 16b・
-----・Groove. Figure 1 Figure 2 Figure 3 Figure 6 Figure 10 Figure 11

Claims (1)

[Claims] A groove with a width wider than the track width for embedding the lower core at least at a position corresponding to the recording track on the nonmagnetic substrate, a lower core formed in the groove, and a groove formed on the lower core and the substrate. a gap material that regulates the gap length; an insulating layer that is formed on the surface of the gap material and has a through hole that regulates the track width; A thin film magnetic head comprising a lower core and an upper core facing each other, the lower core of the thin film magnetic head being wider than the track width and at least adjacent to the adjacent track on the side where the upper core is not formed. A thin-film magnetic head characterized in that the lower cores are cut out so that they do not overlap.