JPS60164913A - thin film magnetic head - Google Patents

Abstract

PURPOSE:To form a thin magnetic head with excellent head performance and mass-productivity by forming a couple of front cores sectioned to the right and left to a nonmagnetic base, forming a rear code while bridging over the front core and patterning a thin film coil to surround a bonded part of both cores so as to eliminate drilling processing. CONSTITUTION:A magnetic thin film is coated by sputtering on the surface of the nonmagnetic base 1 so as to form front cores 3a, 3b. Then the part of gap depth Gd of the front core is avoided, the upper face of the front cores 3a, 3b is bridged over at both legs parted from the sliding face 6 in opposite direction and a rear core 3c made of a magnetic thin film of ''Sendust'' member is formed by coating it by sputtering. The drilling processing to the base or the like which has been indispensable in conventional way is made unnecessary, an operating gap 4 is formed between the front cores 3a and 3b formed on the same plane on the base and the core cross section is enlarged larger than the front gap area, then the thin film coil system with excellent head performance and suitable mass-productivity is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thin film magnetic head suitable for video tape recorders and the like.

[Background of the invention]

In recent years, metal tape has become popular as a magnetic tape for video tape recorders. As a magnetic head suitable for such a metal tape, a thin film magnetic head using a magnetic thin film such as Sendust or Permalloy having a high saturation magnetic flux density as a core material has been proposed.

FIG. 1 is a perspective view showing an example of a conventional thin film magnetic head of this type, in which 11 and 11' are nonmagnetic plates, 12 is a magnetic thin film,
14 is an operating gap, 15 is a winding hole, and 16 is a winding wire.6 In the figure, a magnetic thin film 12 having a thickness corresponding to the track width is attached to two non-magnetic substrates 11. '11' are sandwiched to form a core block, these are polished and holes 15 for winding are processed, both core blocks are butt-bonded via a non-magnetic spacer to form an operating gap 14, and a winding 16 is applied. Obtained a thin film magnetic head.

Since the thin film magnetic head having such a structure is configured to obtain the working gap 14 at the same time as the bonding operation, the condition of the bonding surface directly influences the gap length of the working gap 14. In addition, because bonding is performed after forming a core block divided into left and right sides, there are problems with dimensional accuracy such as track alignment becoming difficult, resulting in poor yields. Furthermore, the structure is disadvantageous in performing multi-processing and multi-bonding of the head.

FIG. 2 is a perspective view showing another example of a conventional thin-film magnetic head, in which 12a and 12b are magnetic thin films, Qd is the gap depth, and other parts corresponding to those in FIG. 1 are given the same reference numerals. .

This example is a thin film magnetic head in which the bonding process has been eliminated, and a first magnetic thin film 12a is crushed on one half of a nonmagnetic substrate 11, and the side surface is processed by cutting or etching to form a surface for a gap 14. forming a non-magnetic substrate 11
A magnetic core is obtained by interposing a non-magnetic spacer between the other half of the magnetic thin film 12b and the same surface of the second magnetic thin film 12b. Next, a winding hole 15 is formed by ultrasonic machining or the like, and a winding 16 is applied to obtain a thin film magnetic head.

In such a thin-film magnetic head, there is no bonding work that directly affects the gap 14, and the magnetic core is formed by repeatedly depositing a thin film on a common non-magnetic substrate 11, so the dimensional accuracy of the track width can be improved. The same applies to a large extent. Furthermore, since there is no gap bonding work, a large number of heads can be manufactured using a large wafer-like substrate, making it highly suitable for mass production.

However, there were the following drawbacks regarding the drilling of the winding hole 15.

First, the dimensional accuracy of the winding hole 15 and the surface accuracy of the inner surface of the winding hole 15 are poor, and therefore the dimensional accuracy of the gap depth Gd is deteriorated. This is due to poor workability of the non-magnetic substrate 11 during drilling and severe wear of the cutting edge. That is, the material for the non-magnetic substrate 11 was selected from glass with high hardness and low abrasion properties in order to reduce head abrasion during tape running.

Ceramic material is used, which makes it a difficult-to-cut material. Furthermore, even for the same material, the drilling process itself is much more difficult than other cutting or grooving processes, and the processing methods are also limited. The second drawback is problems such as deterioration of the magnetic properties of the magnetic thin film and film peeling due to vibration and heat generation during processing. In particular, the area near the gap has a narrow magnetic path cross-sectional area, including the gap depth Gd, and is considered to be a critical area for head characteristics, so characteristic changes during processing have been a problem. Note that a method of performing substrate perforation at the beginning of the manufacturing process may also be considered. According to this method, there is no possibility of any negative effect on the Km thin film, but an unnecessary film adheres to the winding hole during various film deposition processes, and another problem arises as to how to remove this.

As described above, the four-hole machining in the conventional example shown in FIG. 2 causes various damage, and the advantages in dimensional accuracy and quantity machining over the conventional example shown in FIG. 1 are not necessarily utilized.

Furthermore, a common issue between FIGS. 1 and 2 is the problem of the winding work itself. In other words, as is the case with conventional ferrite heads, the winding work cost that accounts for several ten percent of the total head cost, and unless a revolutionary automatic winding machine is developed in the future, it will not be possible to reduce the cost. It's impossible. In this sense, a thin-film magnetic head that does not require winding work, that is, has no winding holes, can be said to be the best in terms of performance and cost.

FIG. 3 is a perspective view showing a thin film magnetic head wound with a thin film coil μ used for computers, etc., where 13 is a magnetic thin film, Ct is a film thickness, Tw is a width, and other symbols same as those in FIG. Show equivalent.

A first magnetic thin film 12 is deposited on the non-magnetic substrate 11, and has a thickness CL and a width Tw equal to the rack width. After wiring the thin film coil 17, a second magnetic thin film 13 is deposited on the first magnetic thin film 12 to form a magnetic core. The tape sliding direction is the direction of the film thickness Ct.

In the case of a thin-film magnetic head with such a configuration, the conditions that do not deteriorate the magnetic flux efficiency during recording and reproduction are that the front gap area Sg = Tw X Qd and the core cross-sectional area Sc =
Tw X Ct becomes Sg(Sc).

From this, it becomes CL)Gd, and the thickness Ct of the magnetic thin film must always be larger than the predetermined gap depth Gd.

Normally, the gap depth Qd is required to be several tens of μm in consideration of the life due to head wear, and under this condition, the thickness Ct of the magnetic thin film must be greater than that, which is not easy in terms of thin film formation. Furthermore, in the case of this head structure, periodic undulations occur in the recording/reproducing frequency characteristics due to the so-called contour effect, which is undesirable. There are ways to avoid this, such as increasing the core length of the sliding surface, but it is not easy as before.

These drawbacks are due to the fact that the gap plane 14 and the magnetic field 912.13 plane are parallel in FIG.
Since the film was formed in the direction in which the film was stacked on the film 1, there was a limit to how thick the film Ct could be, making it difficult to prevent the contour effect.

For this reason, although it can be used as a thin film magnetic head for computers, it is not suitable for use in video tape recorders.

[Purpose of the invention]

An object of the present invention is to provide a thin film magnetic head that eliminates the need for drilling and has excellent head performance and mass productivity.

[Summary of the invention]

In order to achieve this object, the present invention is designed to form a pair of front cores divided into left and right parts on a non-magnetic substrate, and to form a rear core by bridging these front cores, and to form a rear core at the joint between the two cores. There is a '%' mark in that the thin film coil is patterned to surround the area.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a perspective view of an embodiment of the thin film magnetic head according to the present invention, in which 1 is a nonmagnetic substrate, 2 is a nonmagnetic pattern material, and 3 is a nonmagnetic substrate.
A and 3b are front cores, 4 is an operating gap, 5 is a thin film coil, 6 is a sliding surface, and other parts corresponding to those in FIG. 3 are given the same reference numerals.

In the same figure, a non-magnetic substrate with good wear resistance made of glass or ceramic material, thickness Q, 3 mm, 2
The front cores 3a and 3b are cut out from an inch-diameter wafer with a diameter of about 2 mm, and a magnetic thin film is deposited on the surface by sputtering to form front cores 3a and 3b. Its shape is as thick as the track width Tw, one front core 3a is L-shaped, and the other front core 3b is one-shaped, and these are attached to each other's side surfaces on the tape sliding surface 6 side. The actuating gap 4 is formed by abutting against each other. Sendust alloy, which has a high saturation magnetic flux density and excellent magnetic permeability in the video band, was used as the material for the magnetic thin film. The non-magnetic pattern material 2 is formed to separate the front core into an L-shaped portion 3a and an engineering-shaped portion 3b, and to provide a predetermined gap depth Gd on the sliding surface 6 side. . Its shape has a thickness equal to the track @TW, and the sliding surface 61
Although 111 has a single-letter shape with an acute-angled tip, the tip can have other shapes in consideration of magnetic properties. As this non-magnetic pattern material 2, a non-magnetic material such as glass or ceramics is used.
It may be the same material as. The operating gap 4 is located on an extension of one side surface of the non-magnetic pattern material 2, and the gap plane crosses the magnetic thin film in its thickness direction and is inclined at a predetermined azimuth angle with respect to the upper surface of the non-magnetic substrate l. ing. In addition, as a non-magnetic spacer between the front cores 3a and 3b,
.

A film of 0.2 to 0.3 μm is deposited to regulate the gap length. Next, avoiding the cap depth Gd part of the front core, the upper surfaces of the front cores 3aj and 3b are bridged at the leg-like parts that are away from the sliding surface 6 in the opposite direction, and the rear core 3C made of a magnetic thin film of sendust material is connected. was deposited by sputtering.

The area of the rear core 3C was a rectangle of about 1 mm x 2 mm, which provided a sufficient bonding area with the front cores 3a and 3b, and also left room necessary for forming the thin film coil 5 described below. Thin film carp N5 has front core 3
It is formed in a planar shape on the upper surfaces of a, 3b and the non-magnetic pattern material 2, and extends under the rear core 3cK. The thin film coil 5 is located at the front cores 3a and 3b.
One or several turns are formed in a spiral shape around at least one of the joints between the rear core 3C and the L-shaped front core 3a in this embodiment. ).

The material of the thin film coil 5 is copper or aluminum, which has low electrical resistance, and the front core 3a.

An insulating film is provided to prevent electrical short circuit with the 3b'F rear core 3C. Furthermore, although not shown, a non-magnetic film such as alumina was deposited on these to protect the magnetic thin film and the like, thereby increasing the strength of the entire head.

Next, the operation of the thin film magnetic nozzle according to the present invention will be explained. First, the magnetic core has a front U-shaped part 3a, an operating gap 4. Engineering letter part 3b.

A closed magnetic path is formed through the rear core 3C.

Furthermore, since the joint area between the front cores 3a, 3b and the rear core 3C is large enough, the magnetic resistance at that portion 5 is small, so that losses during recording and reproduction can be reduced. The thin film coil 5 is arranged to interlink with this magnetic path. That is, during recording, the magnetomotive force generated by the thin film coil 5 is applied to the joint portion of the front core 3a and the rear core 3C that it surrounds to generate a signal magnetic flux, which is transmitted to the working gap 4 through the magnetic circuit. On the other hand, during reproduction, the signal magnetic flux passing through the junction induces a voltage in the thin film coil I15 interlinked therewith.

These operations are no inferior to conventional wound heads; in fact, the head of this embodiment, which is wound more closely to the magnetic path, can produce less noise. The thin-film magnetic head has a front gap area S g = Gd x T in the shape of its front core.
w, core cross-sectional area Sc=CwXTw, G, d ((
Because Cw, Sg((Sc holds true, recording and reproducing efficiency lags,
The drawbacks mentioned in the conventional example of FIG. 3 have been eliminated. Further, since the core shape of the sliding surface 6 has Cw formed in the width direction of the non-magnetic substrate 1, it can be made sufficiently large with respect to the recording wavelength, and there is no fallout due to the contour effect. Furthermore, in the thin film magnetic head of this embodiment, the gap depth Gd is determined only by the positional accuracy of the nonmagnetic pattern 2 and has high dimensional accuracy. Furthermore, since the drilling process for winding holes is eliminated, there is no deterioration in the characteristics of the magnetic thin film due to the process, making it possible to realize a highly precise, high performance thin film magnetic head.

FIG. 5 is a process diagram showing a specific example of a method for manufacturing a thin film magnetic head using the BAK according to the present invention, in which numeral 3 indicates a front core layer, and other parts corresponding to those in FIG. 4 are given the same reference numerals.

A convex non-magnetic pattern material 2 with a thickness equal to the track width is formed on the non-magnetic substrate 1 by sputtering and etching (FIG. 5(a)), and a magnetic "lj#M" is temporarily attached to form the front core #3. (Fig. 5)).Then, the side surface of the front core layer 3, which should be the gap position, is cut off using a diamond cutting tool or the like, and a predetermined azimuth is formed. At the same time as forming a gap surface 4 with corners, an L-shaped front core 3a is formed (FIG. 5(C)).A 5i01 film for gap regulation is applied to the gap surface to prevent decay magnetic properties. (Fig. 5(d))
, 8i0. Copper, aluminum, etc. are deposited through an insulating film,
Etching is performed to form a thin film coil 5 having a desired number of turns. The thin film coil 5 surrounds the portion that will later become the alignment portion of the rear core, and is formed into a planar shape (FIG. 5(e)). S
! 0! After forming the insulating film, the rear core 3c is formed by connecting the legs of the front cores 3a and 3b on which the magnetic thin film has already been formed (FIG. 5(f)), and in this way the thin film magnetic head is formed. complete.

In the above-mentioned embodiment, the structure is such that there is no winding hole T, so there are no processing problems associated with drilling and winding work, and the production time is reduced, which improves the head cost. can be reduced.

In the above embodiment, one thin-film magnetic head is manufactured on one non-magnetic substrate, but it is possible to manufacture a large number of thin-film magnetic heads at once on a large-area substrate. It is possible to produce T.

FIG. 6 is a perspective view showing another embodiment of the thin film magnetic head according to the present invention, in which 2a and 2b are non-magnetic hatern materials, 3a' is a front core, 4a and 4b are operating caps, and 5a and 5b are thin films. This is a coil, and other corresponding parts to those in FIG. 4 are given the same reference numerals.

This thin film magnetic head has two working gaps 4at4b.
This is a double azimuth head capable of special reproduction with a central front core 3b in common to form two magnetic circuits. An operating gap 4a is formed between the front cores 3a and 3b via an 8i0 insulating film, and an operating gap 4b is formed between the front cores 3a' and 3b via a 5102 insulating film. . rear core 3c
bridges the front cores 3a, 3a', and 3b to form the two magnetic circuits described above. Each magnetic core is provided with a thin film coil 5a, 5b, respectively, and these thin film coils/L15a, 5b are arranged to surround the joint between the front cores 3a, 3a' and the rear core 3C.

Front core 3a, 3a' and thin H coil 5a,
5b and between the thin film coils 5a, 5b and the rear core 3C are magnetically separated by a Sin and insulating film, respectively.

As described above, according to this embodiment, a double azimuth head can be easily obtained, and the same effects as the embodiment shown in FIG. 4 can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, it is not necessary to drill wells into the substrate, which has been indispensable in the past, and by forming an operating gap between the front cores formed on the same plane on the substrate, the front gap area can be reduced. Since the core cross-sectional area was also increased,
It is possible to provide a thin-film magnetic head with excellent head performance and excellent functionality while eliminating the drawbacks of the prior art.

[Brief explanation of drawings]

1, 2 and 3 are perspective views showing conventional examples of thin film magnetic heads, FIG. 4 is perspective views showing one embodiment of a thin film magnetic head according to the present invention, and FIG. 5(a) ~(f)
4 is a process diagram showing a specific example of the method for manufacturing the thin film magnetic head shown in FIG. 4, and FIG. 6 is a perspective view showing another embodiment of the thin film magnetic head according to the present invention. l...Nonmagnetic substrate, 2...Curved nonmagnetic pattern material, 3a, 3a' and 3b...Curved front core, 4,4
a and 4b...Middle working gap, 5.5a and 5
b... Thin film coil. Figure 1 5 4 Figure 2 5 Figure 3 7 Figure 4 Figure 5 Figure 6 4D JG-NO

Claims (1)

[Claims] A thin film magnetic head comprising: a non-magnetic substrate; a magnetic core formed by depositing a magnetic thin film on the non-magnetic substrate and having an operating gap; and a thin-film coil provided on the magnetic core; A pair of front cores are formed on the left and right sides of the non-magnetic substrate with a working gap in between, and are fully open on the working gap side, and a rear core bridges the open circuit portions of both front cores on the working gap side. ,
A thin film magnetic head characterized in that the thin film coil is provided to surround a joint between at least one of the front core and the rear core.