JPH08115509A - Magnetic head and its manufacture - Google Patents

Abstract

PURPOSE: To obtain a magnetic head capable of recording and reproducing with a high density equivalent to a thin film magnetic head and being manufactured easier than the thin film magnetic head, etc. CONSTITUTION: A nonmagnetic block 11 is held between a front magnetic block 12 and a back magnetic block 13 to constitute a magnetic head main body 24. Both magnetic blocks 12 and 13 are magnetically combined by a magnetic yoke 16 via a magnetic gap part 14 on one side surface of this magnetic head main body 24, and the other side surface is magnetically combined by a separate magnetic coil structure 18, thus constituting the magnetic head 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used in a magnetic recording / reproducing apparatus, and more particularly to a magnetic head for high density recording having a narrow track width.

Track density and linear recording density have been improved with the increase in density of magnetic recording. The former is performed by narrowing the recording / reproducing track of the magnetic head, and the latter is particularly performed by reducing the gap length of the reproducing head.

In order to manufacture such a magnetic head,
Processes similar to those used in the manufacture of semiconductor devices are used, namely vapor deposition, sputtering, photolithography and etching.

The thin-film magnetic head manufactured in this manner is excellent in mass productivity because many thin-film magnetic head elements can be simultaneously formed on one substrate, but the magnetic cores and coils, which are the constituent elements of the magnetic head. In addition to forming all of them as thin films, these insulating films are also thin films, so many manufacturing processes are required and the time required for manufacturing is enormous. In addition, if a manufacturing defect that cannot be recovered occurs relatively later in the manufacturing process of the thin-film magnetic head, the manufacturing process is to sequentially stack thin films on one substrate. There is an inconvenience that it is wasted, the manufacturing yield is deteriorated, and the manufacturing cost is increased.

Therefore, Japanese Patent Laid-Open No. 1-251409 discloses a magnetic head which eliminates the defect in the manufacturing process peculiar to the thin-film magnetic head and does not cause a decrease in the magnetic recording density as compared with the conventional thin-film magnetic head. Such a coil thin film magnetic head has been proposed.

As shown in FIGS. 6 and 7, this coil thin film magnetic head has a structure in which a pair of non-magnetic substrates has a magnetic core composed of a thin film.

Specifically, the front cores 2, 2 made of a pair of soft magnetic films sandwiching the magnetic gap 4 are formed on one of the pair of non-magnetic substrates 1, 1 and the other substrate is
A magnetic substrate 8 made of ferrite or the like is joined to form a rear core, a thin film coil 9 is formed, both substrates are joined to cut a part of the coil terminal 10 to form a magnetic head 12.

The coil thin-film magnetic head manufactured in this manner has the same track width as the soft-magnetic film thickness (indicated by t in FIG. 7) formed on the non-magnetic substrate, and is similar to the thin-film magnetic head. The narrow totic can be easily realized. On the other hand, since the rear magnetic core is composed of ferrite, the rear magnetic core is machined, which is a simpler means instead of sputtering or etching like a thin film magnetic head.
That is, dicing or the like can be adopted.

Further, since a step of combining and joining the pair of substrates to form a magnetic head after completion of the above manufacturing process is adopted, even if a manufacturing defect occurs in one substrate and it cannot be recovered, The defect does not reach other substrates. Therefore, unlike the thin film magnetic head, there is no absurdity that all the processes before this are wasted due to such manufacturing defects.

[0010]

As described above, in the coil thin film magnetic head of this type, a part of the manufacturing process of the thin film magnetic head is changed from the thin film process to the mechanized process to facilitate and shorten the manufacturing process. There is an advantage that the manufacturing yield can be improved and the cost can be reduced by dividing a part of the manufacturing process into two independent parts.

However, the front core is still manufactured only by a thin film process, and in particular, as shown in FIGS. 6 and 7, it is necessary to form a wedge-shaped magnetic core when observed from the sliding direction of the medium. Requires a very difficult process such as forming a resist pattern in a wedge shape on the soft magnetic film (FIG. 8a) and etching the entire surface to form the soft magnetic film (FIG. 8b).

The magnetic gap 4 is surrounded by the non-magnetic substrates 1 and 1 on the upper and lower sides and the front cores 2 and 2 on the left and right when observed from the medium sliding surface side. , The magnetic gap depth from the outside (Fig. 7
(A of b and indicated by d in this enlarged view of FIG. 9) could not be directly observed, and it was difficult to process an accurate magnetic gap length. This point is inferior to the so-called bulk magnetic head in which the magnetic gap depth can be directly observed from the outside.

[0013]

SUMMARY OF THE INVENTION The present invention is directed to a non-magnetic material block, a front magnetic material block disposed at one end of the non-magnetic material block, and a back magnetic material block disposed at the other end of the non-magnetic material block. And a magnetic gap portion disposed in the front magnetic body block, a magnetic yoke for magnetically coupling the front magnetic body block and the back magnetic body block via the magnetic gap portion, the front magnetic body block, and Provided is a magnetic head comprising a magnetic coil structure magnetically coupled to a back magnetic material block and arranged on the non-magnetic material block, and at least the magnetic gap portion of the front magnetic material block is arranged. It is preferable that the portion to be formed is a metal magnetic material and the other portion is an oxide magnetic material.
It is preferably a TaCu alloy or a FeTaN alloy.

Further, it is preferable that the magnetic coil structure comprises a bar made of a magnetic material and a coil helically wound around the bar, and the helical coil is preferably a thin film coil. Furthermore, it is preferable that the magnetic yoke is a metal magnetic material, and particularly FeTaNCu alloy or FeTaN alloy.

Further, according to the present invention, a step of joining a front magnetic material block bar to one end of a non-magnetic material block bar and a back magnetic material block bar to the other end, and forming a magnetic gap member group on the front magnetic material block bar. And a step of forming a magnetic yoke group across the front magnetic block bar, the non-magnetic block bar, and the back magnetic block bar via a magnetic gap member, the front magnetic block bar and the back block. Also provided is a method of manufacturing a magnetic head, which comprises a step of magnetically joining one end and the other end of a magnetic bar group in which a coil is wound around each of the magnetic block bars.

[0016]

In the magnetic head according to this structure, the front and rear magnetic cores are composed of magnetic material blocks arranged at both ends of the non-magnetic material block, and are used in a thin film magnetic head or a coil thin film magnetic head for manufacturing. Most machining can be used instead of sputter, photolithography, and etching processes.

In the polishing process of the sliding surface, the magnetic gap length can be directly observed from the side surface.

Furthermore, a magnetic head body composed of a front magnetic body block, a magnetic body yoke, a back magnetic body block, and the like, and a magnetic coil structure are individually manufactured, and after the respective manufacturing processes are completed, the two are integrated to form a magnetic head. Complete. In this way, a part of the manufacturing process can be divided into two independent manufacturing processes.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic head according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an embodiment of the magnetic head of the present invention.

The present magnetic head constitutes a magnetic circuit so as to circulate around the non-magnetic block 11. The magnetic circuit is formed from a magnetic gap portion 14 made of a non-magnetic material such as SiO2 or AlO3 to a magnetic material, particularly a magnetic material. FeTaNCu, F
Magnetic yoke 16 made of soft magnetic thin film such as eTaN alloy
C through the bar made of a magnetic block such as ferrite.
A magnetic coil structure formed by helically winding a wire made of u or the like (see FIG. 2 for details), and a portion in which a magnetic gap portion is arranged is a metal magnetic body portion 15 made of a soft magnetic thin film such as FeTaNCu or FeTaN alloy. , The other part is made of a magnetic material such as ferrite.
(Including)) magnetic circuit configuration.

The side indicated by A in the figure serves as a sliding surface for the medium, and the surface of the magnetic head on the back side of the paper in the perspective view is usually attached to the slider attached to the arm of the hard disk drive or the head base of the VTR head. Fixed.

When the magnetic gap length is optimized by polishing from the sliding surface side while being fixed to the slider or head base in this way, the magnetic gap length is always observed from the side surface (B side). It is possible to process the magnetic gap length more accurately.

Further, in the present embodiment, the metal magnetic body portion 1 arranged in the front magnetic body block is arranged with respect to the magnetic gap.
5 are arranged diagonally. Therefore, as shown in FIG. 9, the magnetic gap depth d can be measured by the film thickness W of the metal magnetic body exposed on the sliding surface side.

Specifically, the magnetic gap d is the film thickness t of the metal magnetic body portion 15, the exposed film thickness W of the metal magnetic body exposed from the sliding surface, and the angle formed by the metal magnetic body and the magnetic gap. It can be expressed by the following formula by using Θ.

D = t−W · Cos Θ / Sin Θ

Generally, from the viewpoint of magnetic properties and film peeling, the film thickness t of the metal magnetic material portion 15 is about 3 to 30 μm, and the angle Θ between the metal magnetic material portion 15 and the magnetic gap 14 is 15 ° to.
It is better to set it to about 75 °.

Between the magnetic substance such as ferrite of the front magnetic substance block 12 and the soft magnetic thin film of FeTaNCu, FeTaN alloy or the like, the adhesion between the two is improved and mutual diffusion due to heat is prevented. , Cr, Ta, N
It is effective to dispose oxides, nitrides, and carbides of i, Co, Zr, Mo, Al, Si and the like.

It is also effective to dispose the oxide or the like on the upper surface of the magnetic yoke 16 in order to prevent the deterioration of the magnetic yoke 16 made of FeTaNCu, FeTaN alloy or the like (part indicated by 17). The front magnetic body block 12 and the back magnetic body block 13 need to have a volume most suitable for constructing a magnetic circuit, and if the volume is too large, it is advantageous for sticking to both blocks of the magnetic coil structure. However, the inductance of the magnetic head increases, and the recording / reproducing efficiency of the magnetic head decreases. On the contrary, if only the reduction of the inductance is taken into consideration, it becomes difficult to attach the blocks to both blocks, and the magnetic resistance increases at this joint, which is not preferable.

The magnetic coil structure 18 includes the front magnetic block 12 and the back magnetic block 1 as described above.
3 is attached, but a joint portion for this is required.

FIG. 2 is a perspective view before the magnetic coil structure is connected to the magnetic head body 24. Magnetic coil structure 18
Is a magnetic bar 21 made of a magnetic thin film on the non-magnetic plate 19.
Coil with helically wound conductive metal thin film above and below
0. Both ends of this magnetic bar are magnetically coupled to the joining portions 22 and 23 to be attached to the front magnetic block and the back magnetic block described above. The helically wound coil 20 is electrically joined to the coil terminal 23 for electrical connection with the outside.

As the magnetic thin film constituting the magnetic bar 20, a soft magnetic film made of FeTaNCu or FeTaN alloy, a NiFe soft magnetic film, a sendust-based soft magnetic film made of FeAlSi, or FeMnN, FeCo is used.
A soft magnetic film made of an alloy such as N or FeCrN can be used. However, when the soft magnetic film is electrically conductive, the insulation with the helically wound coil is made by SiO 2.
It is necessary to use 2 or AlO3.

When the soft magnetic film is electrically conductive, a so-called overcurrent loss is eliminated, so that a soft magnetic thin film and an insulating film can be laminated.

Since the coil is helically wound as shown in FIG. 2, the number of turns per unit area is large as compared with the case where the coil is flatly wound like a conventional general thin film magnetic head. can do.

Although not shown, in order to increase the number of turns of the coil, the winding can be doubled or tripled, and the shape of the magnetic bar can be S-shaped.

The magnetic coil structure and the front and back magnetic material blocks may be bonded by any material as long as they form an extremely thin adhesive layer.

The thickness of the adhesive layer largely depends on the viscosity of the adhesive, but if the viscosity is made sufficiently small, an adhesive layer of about 50 Å can be realized, and the magnetic head body 24 and the magnetic coil structure 18 can be realized. The magnetic resistance between and can be made sufficiently small.

Next, a method of manufacturing the magnetic head according to the present invention will be described. First, regarding the magnetic head main body, a front magnetic body block similarly prepared is joined to one end of a non-magnetic body block formed in a predetermined shape by slicing, dicing, etc., and a back magnetic body block is joined to the other end. . For example, when manufacturing the magnetic head having the shape shown in FIG. 2, the non-magnetic material block is processed into a trapezoidal shape in advance as shown in the drawing. At this time, particularly in the portion where the magnetic gap is formed, the magnetic gap length is accurately kept constant and the surface roughness is improved in order to prevent short circuit of the magnetic flux in the magnetic gap.

Generally, the surface roughness is preferably 50 angstroms or less, and is realized by lapping. The non-magnetic material block 11 and the two magnetic material blocks 12 and 13 are bonded to each other by spattering glass (not shown) as an adhesive on the bonding surface and melting the glass in a heating furnace under a constant pressing force to bond the glass. To do. Metal magnetic material part 15 of the front magnetic material block
If glass is directly sputtered on the above to perform the above-mentioned joining, the magnetic characteristics of the magnetic material may deteriorate during heating. This occurs because the components contained in the glass diffuse into the magnetic substance, and the components contained in the magnetic substance diffuse into the glass. In such a case, Al2 O3, before sputtering the glass,
SiO3, Ti, Cr or the like can be used as a buffer material.

Next, SiO2, Al2 O3 or the like having a predetermined thickness is formed as a gap material on the surface where the magnetic gap is to be formed in the upper portion 15 of the metal magnetic body of the front magnetic body block 12. Generally, sputter deposition or a photolithography process is used, but it is possible to more easily form the gap material by disposing a cover made of metal or the like on the surface other than the planned magnetic gap formation surface and sputtering the entire surface. .

Next, the magnetic material yoke 16 is formed on the surfaces of the front magnetic material block 12, the non-magnetic material block 11 and the back magnetic material block 13 including the magnetic gap formation surface on which the magnetic gap material is arranged. This is possible with a process similar to the process of forming the magnetic gap material,
It is easy to use a cover made of metal or the like as described above.
Finally, the protective layer 17 for protecting the magnetic yoke 16 is formed by the same method. The magnetic yoke 16 and the protective layer 17 may be formed at the same time.

The above is the outline of the method of manufacturing the magnetic head body 24. When actually manufacturing the magnetic head body 24, it is desirable to carry out the above steps in block bar units in view of mass productivity and the like. A case where the above steps are performed in block bar units will be described below with reference to FIG.

First, as shown in a, the front magnetic block bar 28 and the back magnetic block bar 31 are joined to both ends of the non-magnetic block bar 30 (a). Bonding is performed by using glass or the like as described above, but if the flatness of the bonding surface of each block bar is not good, a gap or the like will not occur at the bonding interface. The length of the block bar is 50-100m
It is preferable that the flatness of the joint surface is about 1 μm or less when the thickness is about m.

At the time of glass joining, the front and back magnetic material block bars 28 and 31 are pressed by a jig to sandwich the non-magnetic material block bar 30, but a uniform pressing force is obtained over the entire bonding surface of the block bars. Therefore, it is effective to make the front and back block bars 28, 31 sufficiently thick. Next, as described above, a group of magnetic gaps and magnetic yokes is formed over the entire surface of the block bar assembly 25 (b).

The block bar intermediate structure 26 thus completed is cut as shown by the chain line in FIG. C to obtain the magnetic head body 24. It should be noted that this cutting width is sufficient if it is about the track width, but if the track width is extremely thin, about 3 to 10 μm, the mechanical strength will be insufficient, so that it is usually 0.
Cut into a width of about 5 to 1 mm. In this case, the track width is processed together with the magnetic gap depth and the HDD is processed.
After being attached to the slider of the head or the head base of the VTR head, the vicinity of the magnetic gap is ground and sliced to a predetermined thickness.

The processing in block bar units can be carried out for one set of block bar bonded bodies as described above, but as shown in FIG. 4, it is also possible to collectively manufacture a plurality of block bar groups. . In this case, as shown in FIG. 4, front and back magnetic block bars 36 and stacking non-magnetic block bars 37 are alternately joined to form a block bar group, which is cut as shown in FIG. A set of block bar joined bodies 26 is obtained. At this time, the front and back magnetic material blocks are cut as shown in FIG. 3D, so that the one on the left side of the dashed line in the drawing is paired with the laminating non-magnetic material block bar 37 on the left side thereof. The magnetic material block bar is cut, and the cut right side becomes a front magnetic material block bar which is paired with the right non-magnetic material block bar.

After that, the magnetic gap and the magnetic yoke are formed as described above, and cut at the alternate long and short dash line portion to obtain a set of block bar joined bodies 26. At this time, a part of the magnetic gap member remains on a part of the back magnetic block bar (portion e in the figure), but this does not pose a problem in terms of magnetic characteristics.

Next, a method of manufacturing the magnetic coil structure will be described. FIG. 5 shows an embodiment of manufacturing the magnetic coil structure of the magnetic head of the present invention. In FIG. 5, the right side column is a plan view showing the manufacture of the magnetic coil assembly, and the left side column is the X side of this plan view.
It is sectional drawing which shows -X cross section.

First, a first coil conductor 20a is formed on a non-magnetic and insulative substrate 19 made of ceramics or the like prepared in advance, for example, as shown in FIG. At the same time, the coil terminal 23 is electrically connected to a part of the first coil conductor. Next, the magnetic bar 21 is formed on the coil. When the magnetic bar is a conductor, an insulating layer is formed on the first coil 20a to insulate it from the first coil 20a.

The insulating layer may be made of Al2 O3, SiO2 or the like, and when the magnetic bar 21 is formed of a thin film, it is flattened so that the step is not transferred to the magnetic bar 21 by the first coil. Is preferable. The flattening can be performed by flattening the surface of the insulating layer after sputtering or vapor deposition.In addition, when the insulating layer is formed by sputtering, the sputtering is performed while applying a negative voltage to the surface on which the sputtered film is formed. The surface of the insulating layer can be planarized by the so-called bias sputtering.

The magnetic bar is formed by projecting both ends thereof as shown in FIG. Since this portion is used as the bonding portions 22 for attaching to the front magnetic body block and the back magnetic body block, it is preferable to form it higher than the upper surface of the second coil 20b to be formed later.

In order to project both ends in this way,
It is conceivable that a magnetic material is formed in advance on a thick film and then the central portion is etched so that both ends are projected, or that convex portions are provided on the substrate in advance and this is transferred. Then the first coil 2
The second coil 20 through the necessary insulating layer and the like as in the case of 0a.
b is formed on the magnetic bar. At this time, the upper end of the first coil and the lower end of the next first coil are sequentially joined so as to form a helical winding together with the first coil.

Note that an unnecessary insulating layer for electrical conduction is removed by etching or the like. Thus, the magnetic coil structure 18 is formed.

Finally, the magnetic head body and the magnetic coil structure are magnetically and mechanically joined under predetermined conditions, and if necessary, track processing is performed as described above. In this way, the magnetic head of the present invention is manufactured.

[0054]

As described above, since most of the magnetic circuit is composed of a bulk material, a machining process can be adopted instead of the so-called wafer process, which facilitates manufacturing and shortens manufacturing time. To be

Since the magnetic gap depth can be directly or directly observed from the outside while being processed as described above, the accuracy of the magnetic gap depth can be improved.

Further, since the manufacturing process is divided into manufacturing for the magnetic head main body and manufacturing for the magnetic coil assembly independently, even if an unrecoverable manufacturing defect occurs, the other one is a non-defective magnetic head main body. , Or in combination with a magnetic coil structure, the manufacturing yield is improved and the cost can be reduced as compared with a normal thin film magnetic head.

Further, since the helically wound coil can be adopted as the magnetic coil structure, the number of coil turns per unit area should be increased as compared with a normal thin film magnetic head in which a thin film coil is formed on a plane. Is possible,
In particular, the structure has an advantage that the coil forming space is not limited by the track width.

Since the manufacturing method of the present invention can be manufactured by using the bar-shaped block, there is an effect that many magnetic heads can be manufactured at one time.

Regarding the recording and reproducing ability, a part of the front magnetic body block or the magnetic yoke is made of FeTaNCu or F.
Since a high performance material such as an eTaN alloy, that is, a material having a high saturation magnetic flux density can be used, a magnetic head suitable for high density recording and reproduction can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetic head of the present invention.

FIG. 2 is a perspective view showing a magnetic head main body and a magnetic coil structure of an embodiment of the magnetic head of the present invention before being connected.

FIG. 3 is a perspective view showing a process of a magnetic head main body portion of an embodiment of the magnetic head manufacturing method of the invention. a is a perspective view of a completed block bar assembly. FIG. 6B is a perspective view of a block bar intermediate structure in which a magnetic gap portion and a magnetic yoke are formed on the block bar assembly. FIG. 3C is a perspective view showing a cutting line for cutting the block bar intermediate structure to obtain the magnetic head main body. d is a diagram of the magnetic head body.

FIG. 4 is a perspective view showing a process of a magnetic head body according to another embodiment of the magnetic head manufacturing method of the invention. FIG. 5A is a side view showing a minimum unit of joining when a magnetic head body of the present invention is manufactured using a block bar group. FIG. FIG. 5B is a side view showing a state in which a plurality of block bar joined bodies are arranged and integrated. c is
The side view which formed a magnetic gap part and a group of magnetic yokes in a group of block bar junctions. FIG. 3D is a side view showing a cutting line for cutting the group of block bar bonded bodies in which the magnetic gap portion and the magnetic yoke are formed to obtain the magnetic head main body.

FIG. 5 is a perspective view showing a process of manufacturing a magnetic coil assembly according to an embodiment of the magnetic head manufacturing method of the invention. a is a plan view and a side view showing an insulative substrate prepared in advance. b
FIG. 4A is a plan view and a side view showing a state in which the first coil is formed. c is a plan view and a side view showing a state in which an insulating layer and a magnetic bar are formed. d is the second on the magnetic bar
FIG. 5 is a plan view and a side view showing a state in which an insulating layer with respect to the coil of FIG. e is a plan view and a side view showing a state in which the second coil is formed.

FIG. 6 is a perspective view of a coil thin film magnetic head which is a conventional magnetic head.

FIG. 7 is a perspective view showing a process of manufacturing a coil thin film magnetic head which is a conventional magnetic head. FIG. 3A is a perspective view showing one non-magnetic substrate before forming a front core. FIG. b is a perspective view showing a state in which a front core is formed. FIG. 3C is a perspective view showing a state in which a ferrite substrate serving as a rear core is joined to the other nonmagnetic substrate before the thin film coil is formed. d is a perspective view showing a state in which a thin film coil is formed on the other non-magnetic substrate and ferrite substrate. e is a diagram showing a state in which both non-magnetic substrates are joined. f is a perspective view in which a part of the bonded substrates is cut to expose a coil terminal.

FIG. 8 is a front view seen from the medium sliding surface side showing a step of forming a magnetic coil of a coil thin film magnetic head which is a conventional magnetic head. FIG. 3A is a front view showing a state in which a wedge-shaped resist is formed on the metal magnetic thin film. b is a front view showing a state in which one of the front cores is formed in a wedge shape. c is
The front view which shows the state which formed the gap material in order to form a magnetic gap part. d is a front view showing a state in which a magnetic gap portion is formed. e is a front view showing a state in which the other front core is formed. f is a front view showing the completed magnetic core.

FIG. 9 is a schematic side view showing the main part of the tip of the magnetic gap of the magnetic head of the present invention for explaining the observation of the magnetic gap length.

[Explanation of symbols]

 Reference Signs List 11 non-magnetic material block 12 front magnetic material block 13 back magnetic material block 14 magnetic gap portion 15 metal magnetic material portion 16 magnetic material yoke 18 magnetic coil structure 22 magnetic head 24 magnetic head body

Claims (8)

[Claims] 1. A non-magnetic block, a front magnetic block disposed at one end of the non-magnetic block, a back magnetic block disposed at the other end of the non-magnetic block, and a front magnetic block disposed at the front magnetic block. And a magnetic yoke that magnetically couples the front magnetic block and the back magnetic block via the magnetic gap, the front magnetic block, and the back magnetic block. And a magnetic coil structure that is disposed on the non-magnetic block by being physically coupled to each other. 2. The magnetic head according to claim 1, wherein at least a portion of the front magnetic body block where the magnetic gap portion is arranged is a metal magnetic body, and the other portion is an oxide magnetic body. 3. The FeTaN alloy or /
The magnetic head according to claim 2, wherein the magnetic head is FeTaNCu alloy. 4. The magnetic head according to claim 1, wherein the magnetic coil structure comprises a bar made of a magnetic material and a coil helically wound around the bar. 5. The magnetic head according to claim 4, wherein the helically wound coil is a thin film coil. 6. The magnetic head according to claim 1, wherein the magnetic yoke is a metal magnetic body. 7. The magnetic head according to claim 1, wherein the magnetic yoke is made of FeTANCu alloy. 8. A step of joining a front magnetic block bar to one end of a non-magnetic block bar and a back magnetic block bar to the other end, and a step of forming a magnetic gap member group on the front magnetic block bar. Forming a magnetic yoke group across the front magnetic block bar, the non-magnetic block bar, and the back magnetic block bar via a magnetic gap member; and the front magnetic block bar and the back magnetic block bar. And a step of magnetically joining one end and the other end of a magnetic bar group in which a coil is wound around each of the above.