JPH0622045B2 - Manufacturing method of core for composite type magnetic head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a core for a composite magnetic head, and more particularly to a magnetic head suitable for recording / reproducing a high frequency signal such as a VTR, especially for a high coercive force medium. The present invention relates to a method for advantageously manufacturing a core for a composite magnetic head, which provides a suitable composite magnetic head.

(Background Art) In a high density magnetic recording / reproducing apparatus, it is known that it is advantageous to increase the coercive force: H _C of the magnetic recording medium, but in order to record information on the magnetic recording medium having a high coercive force. Needs to increase the leakage magnetic field from the magnetic head.
However, at present, the ferrite material used for the core of the magnetic head has a saturation magnetic flux density: B _S of 40.
Since it is from 00 to 5000 gauss, there is a limit to the strength of the recording magnetic field that can be obtained, and when the coercive force of the magnetic recording medium exceeds 1000 Oersted, there is a drawback that recording is insufficient.

On the other hand, a magnetic head using a crystalline alloy such as an Fe-Al-Si alloy (sendust) Ni-Fe alloy (permalloy) or an amorphous alloy, which is a general term for metallic magnetic materials, generally has a saturation flux higher than that of a ferrite material. It has excellent characteristics of high density and low sliding noise. However, in a commonly used track width (10 μm or more), the effective magnetic permeability in the video frequency region is lower than that of ferrite due to the eddy current loss, and the reproduction efficiency is lowered. Also, it is several steps inferior to ferrite in terms of wear resistance.

Therefore, in order to solve the above problems, various cores for a composite type magnetic head have been proposed in which ferrite and a metal magnetic material are combined and the advantages of both are utilized. For example, Japanese Patent Application Laid-Open No. 58-155513. JP-A-61-265
Various structures are disclosed in Japanese Patent Application Laid-Open No. 714, Japanese Patent Application Laid-Open No. 61-273706, and the like.

By the way, such a conventionally proposed composite magnetic head core is manufactured, for example, as follows. That is, a ferrite film having a corrugated uneven surface is formed by applying a resist film in which slits are formed in stripes to a predetermined ferrite block, and etching is performed. Then, such a corrugated uneven surface is formed. After forming a magnetic layer made of a metallic magnetic material on the surface, polishing the surface to a flat surface, forming a plurality of grooves defining the track width in parallel with each other, and forming a groove for coil winding. After that, the two ferrite blocks are combined and joined to form an integral combined joint, and then this ferrite block combined joint is cut at a predetermined position to obtain the desired composite magnetic field. The head core is sequentially cut out.

However, in such a method for manufacturing a core for a composite magnetic head, two ferrite blocks each having a groove for defining a track width are used, and the ferrite blocks are combined and joined together to form an integrated structure. Since it is a combined bonded body, grooving processing for the track width defining groove for each ferrite block is of course required to be extremely strict, and of course, those ferrite blocks should be opposed to each other. In order to combine them together, it is necessary to align the tracks of each Ferib lock, which is also a very troublesome and difficult task, and if this track alignment is not perfect, track misalignment will occur. Is caused, and this is the ferrite core, and thus the composite. The quality of the core so that the will be allowed to decrease.

In short, the method of manufacturing a core for a composite magnetic head according to the method of combining two ferrites having such track width defining grooves has some difficulties in practical use, It was not able to be adopted to advantage.

(Object of the Invention) Here, the present invention has been made in view of the above circumstances, and an object of the present invention is to solve the problems in the conventional core for a composite type magnetic head and the manufacturing method thereof. The present invention provides a core for a magnetic head exhibiting excellent recording / reproducing characteristics even for a high coercive force recording medium, and an easy manufacturing method therefor. Particularly, it improves track width accuracy and prevents track displacement. In addition, by combining the lithography technology and the etching technology, the core for the composite type magnetic head having no contour effect in the reproduction output,
It is to manufacture with good yield and with advantage.

(Structure of the Invention) In order to achieve the above object, the present invention forms an annular magnetic path by abutting a pair of ferrite blocks, while forming a gap with a predetermined gap at the abutting portions of the ferrite blocks. In a method of manufacturing a magnetic head core using a combination bonded body formed by: Direction, and a second step of forming an uneven surface by etching at least the gap forming portion of the ferrite block abutting surface through the exposed portion not covered with the resist. , (C) A predetermined metal magnet is formed on the etched butting surface of the ferrite block. A third step of depositing a material, (d) a fourth step of removing at least the deposited portion of the metal magnetic material of the ferrite block to a predetermined thickness to make it flat, and (e) the fourth step. Prior to the fourth step or after the fourth step, a fifth step of forming a groove for coil winding on the butt surface of at least one of the pair of ferrite blocks, and (f) the first to fifth steps. The sixth step of forming a non-magnetic layer having a predetermined thickness on at least the gap forming portion of the abutting surface of at least one of the pair of ferrite blocks after the step, and (g) the pair of steps after the sixth step. In the seventh step, the gap forming portions of the abutting surfaces of the ferrite blocks are opposed to each other and are joined to each other to be integrated, and (h) such a combined joined body is provided with a track width defining groove. To An eighth step of forming in a direction orthogonal to the cap, (i) a ninth step of burying a predetermined non-magnetic material in the track width defining groove, and (j) burying the non-magnetic material And a tenth step of cutting the combined joined body at a predetermined position to obtain at least one composite magnetic head core. It is what

In the method of the present invention, the etching shape of the gap forming portion of the ferrite block formed in the second step is advantageously
The shape does not have a parallel portion.

In the eighth step of the method of the present invention, when forming the groove for defining the track width, the groove is formed in the groove forming portion of the combined assembly of the ferrite blocks, in other words, the groove is formed. After applying a resist so that the exposed portion is exposed, etching is performed to form a groove for defining the target track width, and by laser irradiation, or in a reaction solution or a reaction gas. In general, a method of irradiating a laser to form a groove for defining a target track width is adopted.

(Specific Configurations and Examples of the Invention) By the way, in the present invention, a pair of ferrite blocks that provide a combined bonded body used for manufacturing an intended core for a composite magnetic head has a high permeability of a conventional one. Ferrite material with magnetic susceptibility is used, and generally, it is used as a long plate-shaped block having a predetermined thickness so that a plurality of cores for magnetic heads can be manufactured, and their abutment forms an annular magnetic path. Of. In addition,
As the ferrite block with high magnetic permeability, Mn-Z
A single crystal or a polycrystal such as n-ferrite or Ni-Zn ferrite, or a composite thereof is used. In particular, when a single crystal is used, (100), (1)
Crystal planes such as 10), (311), and (332) will be advantageously selected as the magnetic gap forming surface (ferrite block butt surface).

Then, in the present invention, first, in the first step, two (a pair) of the ferrite blocks as described above are used, and at least a magnetic gap forming portion of a butting surface of at least one of the ferrite blocks with respect to the other ferrite block. On the other hand, a predetermined resist is applied, and patterning is sequentially performed at a predetermined pitch in the track width direction. That is, as shown in FIG. 1 and FIG. 2, a resist film 6 having slits 4 at predetermined intervals is provided at least at a gap forming portion of the abutting surface (gap forming surface) of at least one ferrite block 2. They are arranged and formed. The arrangement direction of the resist films 6, 6 ... Is the width direction of the tracks formed on the ferrite block 2, and the width and arrangement interval of the resist films 6 are appropriately set according to the crystal plane of the ferrite. If, for example, the abutting surface of the ferrite block 2 is the (100) surface, the resist width is 15 μm and the interval is 1 μm.
A value of about m is adopted.

Next, in the second step, the abutting surface of the ferrite block 2 provided with the resist film 6 is subjected to an etching operation, and the abutting of the ferrite block 2 is performed through the slit 4 portion where the resist is not adhered. The surface is etched. In addition, this etching operation,
Techniques such as chemical etching and electrolytic etching will be adopted. By this etching, the abutting surface of the ferrite block 2 becomes an uneven surface 8 as shown in FIG. 3. The shape of the uneven surface 8 varies depending on the pattern of the resist film 6. FIG. 4 shows an example of the uneven surface 8 which is different from the shape shown in FIG.

As described above, the uneven surface 8 of various forms is formed by the etching operation at least in the gap forming portion of the abutting surface of the ferrite 2, but in any case, the surface form is the gap facing surface. On the other hand, it is etched in a shape having no parallel portion, and for that purpose, the crystal plane of the ferrite block 2 to be etched, the width of the resist film 6, the spacing of the resist film 6 (slit 4 The width), the etching depth, etc. will be appropriately selected. Of course, the etched butt surface of the ferrite block 2 shown in FIG. 4 has a parallel portion which is parallel to the gap facing surface between the uneven surface 8 having the mountain shape. If the track is formed so as not to have a portion, in other words, if the portion of the uneven surface 8 is located in the magnetic gap portion of the core chip to be cut out, a problem such as contour effect is caused. There is no.

Then, in a third step, a predetermined metal magnetic material is coated on the etched surface of the ferrite block 2 subjected to such an etching operation in a predetermined thickness by an operation such as sputtering, vapor deposition, plating, or CVD. Be dressed. In addition, as the metal magnetic material to be deposited, Fe-Si alloy (Si = 6.5% by weight), Fe-A
There are crystalline alloys typified by 1-Si alloy (Sendust), Ni-Fe alloy (Permalloy), and Fe-C.
Fe-Si, Fe-A in which an amorphous alloy such as a metal-metalloid alloy represented by o-Si-B system or a metal-metal alloy represented by Co-Zr-Nb system is used.
When using the 1-Si alloy, elements such as Cr, Ti, and Ta of 5 wt% or less are appropriately added in order to improve the corrosion resistance. There are various methods for depositing these metallic magnetic materials as described above, but the material to be deposited is not limited, and sputtering with small composition fluctuations is preferably used. FIG. 5 shows a state in which a metal magnetic layer 10 formed by depositing a metal magnetic material with a predetermined thickness on the etched uneven surface 8 of the ferrite block 2 is provided.

Further, thereafter, the ferrite block 2 in which the metal magnetic layer 10 made of such a metal magnetic material is formed to have a predetermined thickness is subjected to a normal cutting and polishing operation with respect to the gap facing surface (butting surface). The unnecessary portion of the magnetic layer 10 is removed (fourth step). That is, by removing a predetermined thickness portion of the gap facing surface of the ferrite block 2 on which the metal magnetic layer 10 which is a metal magnetic material adhered layer is formed, while leaving the metal magnetic layer 10 with a predetermined thickness,
The gap abutting surface is flattened.

Also, prior to or after the fourth step,
A groove 12 for coil winding is formed in the gap facing surface of at least one of the pair of ferrite blocks (2) in the same manner as in the prior art, for example, as shown in FIG. 7 (fifth step). After that, surface polishing is performed to obtain a final finish and a gap facing finish surface is formed. At this time, the metal magnetic material (10) at the gap facing portion is formed.
Such a final finishing operation will be carried out so that the thickness of the sheet will be a predetermined amount.

In addition, the ferrite block 2 obtained in the fifth step
SiO ₂ in at least the gap facing portion (gap forming portion) of at least one of the gap facing finished surfaces of
A non-magnetic material for forming a gap, such as glass, is deposited to a predetermined thickness by sputtering (sixth step).

Then, in the pair of ferrite blocks 2 and 2 obtained in the sixth step, in the seventh step, the finished surfaces facing each other are opposed to each other, and the glass rod is inserted into the winding groove and heated and pressed. In this way, they are joined and integrated into a combined joined body 14 as shown in FIGS. 8 and 9. When the pair of ferrite blocks 2 and 2 are integrally joined, a non-magnetic layer having a predetermined thickness provided in the sixth step is present in the abutting portion so that a gap corresponding to the thickness of the non-magnetic layer is formed. The gap 16 will be formed.

Next, in the assembled assembly 14 of the ferrite blocks joined in the seventh step, a track width defining groove 18 is formed on the surface where the gap 16 is located by a groove processing using a normal grindstone or the like, for example, as shown in FIG. As shown by the broken line in FIG. 9 and over the entire core width, they are formed parallel to each other in the direction orthogonal to the gap 16. Depending on how the track width defining groove 18 is formed, the shape of the boundary portion of the metal magnetic layer 10 in the track portion 20 sandwiched by the track width defining grooves 18, 18 is variously selected as shown in FIG. To get. Further, the shape of the boundary portion of the metal magnetic layer 10 is such that the corrugated shape or the mountain shape of the metal magnetic layer 10 (uneven surface 8) formed in the pair of ferrite blocks 2 and 2 is symmetrical with the magnetic gap 16 interposed therebetween. In the case of FIG. 8 joined so that
As shown in FIG. 0, the metal magnetic layers 10, 10 formed on both sides of the gap 16 have a symmetrical shape, and as shown in FIG. 9, the shape of the metal magnetic layer 10 is asymmetric. In the state of, in the combined joined body 14 in which the pair of ferrite blocks 2 and 2 are joined,
The tracks 20 having the metal magnetic layers 10, 10 providing the boundary portions of various forms on both sides of the magnetic gap 16 are formed.

In the eighth step of inserting the track width defining groove 18, as the groove processing method, in addition to the groove processing using the grindstone as described above, a groove processing method of covering with a resist and removing by etching can be adopted. Further, it is also possible to perform etching by laser irradiation or laser-induced etching (laser irradiation in a reaction liquid or reaction gas) without using a mask made of resist or the like. If such a grooving method is adopted, the track width defining groove 18 can be provided only in the region near the magnetic gap 16 as shown in FIG. 11 unlike the case of the above example. It will be possible.

Then, in a ninth step, a predetermined non-magnetic material is embedded in the track width defining groove 18 provided in the combined bonded body 14. The non-magnetic material includes glass,
A ceramic-based inorganic adhesive, a hard resin, or the like can be applied, but it is preferable to use glass from the viewpoint of stability such as medium running property. Compared with the glass used for gap bonding in the seventh step, the glass used to fill the track width defining groove
If a glass having a lower melting point is used, it becomes easier to prevent the displacement of the track position. Further, when melting and burying the glass in the track width defining groove, if a jig is appropriately used to press and pour the two blocks, it is necessary to worry about the track position shift. Further, unnecessary portions of the embedded non-magnetic material exposed on the medium running surface are removed, and grinding is performed with a grindstone or the like so as to have a predetermined depth length. It is desirable that the grinding process using a grindstone or the like be performed so that the running surface of the magnetic recording medium has a rounded surface. By the grinding process, as shown in FIGS. 13 to 15, the non-magnetic material 22 and the track portion 2 embedded in the track width defining groove 18 are formed.
The ferrite portion forming 0, and further the metal magnetic layer 10,
Each of the gaps 16 is exposed on the medium running surface.

Then, as shown in FIGS. 13 to 15 thus obtained, a predetermined non-magnetic material 22 is placed in the track width defining groove 18.
As a tenth step, the combined bonded body 14 in which the cores are embedded has a required core as shown by a dashed line in the figures centering on the track portion 20 sandwiched by the track width defining grooves 18, 18. The non-magnetic material 22 has a width T.
By cutting at the filled track width defining groove 18 portion, the desired composite magnetic head core is sequentially cut out, and at least one of them is obtained. Incidentally, when cutting out the core, a method of tilting by an azimuth angle and cutting the core may be adopted depending on the case.

The structure of the composite magnetic head core obtained according to the method of the present invention is shown in FIGS. 16 and 17 as a perspective view. That is, the composite magnetic head core 24 shown in FIG. 16 is obtained from the combined bonded body 14 shown in FIG. 13, and the composite magnetic head core 26 shown in FIG. In each case, a magnetic gap 28 having a predetermined gap is formed by the gap 16 exposed on the surface of the track portion 20, which is obtained from the combined joined body 14 having the structure shown in FIG. And
As is well known, a coil is wound around the cores 24 and 26 by utilizing the hole 30 formed by the groove 12 for coil winding, and thus the desired composite magnetic head is obtained. It is.

The method for manufacturing the magnetic head core according to the present invention has been described above in detail based on the manufacturing example of the VTR magnetic head core, but the present invention is construed as being limited to only the specific examples. The present invention is by no means intended, and can be carried out in a form in which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention, and such an embodiment. It is to be understood that both are within the scope of the invention.

Further, the method for manufacturing the composite magnetic head core according to the present invention is not limited to the illustrated VTR head, and is applicable to the manufacture of cores for magnetic heads such as FDD heads, RDD heads, and DAT heads. Needless to say, is also applicable.

(Effects of the Invention) As is apparent from the above description, in the method for manufacturing the composite magnetic head core according to the present invention, (a) the main magnetic circuit of the obtained composite magnetic head core is made of ferrite. The magnetic metal material may be present only in the vicinity of the magnetic gap, so that the eddy current loss can be reduced as compared with the conventional one. (B) The surface of the ferrite on which the magnetic metal material is deposited is uneven. Since it is a surface, and because it has a structure in which there is no flat portion, regardless of the alignment at the time of gap joining, and further, the formation position of the track width defining groove,
The joint boundary surface between the ferrite and the metallic magnetic material in the track is
The structure is inclined with respect to the magnetic gap (gap surface), so that the influence of the contour effect due to the pseudo gap can be ignored. (C) Compared with the conventional manufacturing method in which gap junction is performed after forming the track width defining groove, Since the groove for defining the track width is formed after the combination bonded body is formed by bonding, strict control of the groove processing of the two ferrite blocks constituting such a combination bonded body and track alignment It has a number of great advantages, such as no operation required, and no need to consider the displacement of the track.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part showing a state where a resist film is applied to a ferrite block, FIG. 2 is an enlarged partial sectional view thereof, and FIG. 3 is an uneven surface by etching on one surface of the ferrite block. FIG. 4 is a partial cross-sectional view showing a ferrite block in which different concave and convex surfaces are formed, and FIG. 5 is a perspective view showing the state in which different concave and convex surfaces are formed. FIG. FIG. 6 is a perspective view of an essential part showing a state where the magnetic layer is formed with a predetermined thickness, and FIG.
FIG. 7 is a perspective view of an essential part showing a state in which the metal magnetic layer is removed by a predetermined thickness to be flattened, and FIG. 7 is a grooving process for coil winding on a ferrite block provided with the metal magnetic layer. It is a perspective view which shows the form which gave. Also, FIGS. 8, 9, and 11 are plan explanatory views showing a magnetic gap exposed portion of a combined bonded body in which a pair of ferrite blocks are butted to each other to form a magnetic gap, and FIG. FIG. 12 and FIG. 12 are, respectively, for the combined assembly of FIG. 8 and FIG.
FIG. 16 is a plan view showing a state in which different track width defining grooves are provided, and FIGS. 13, 14 and 15 show different combination bonded bodies in which a non-magnetic material is embedded in the track width defining grooves. It is a principal part top view which shows an example. Further, FIGS. 16 and 17 are perspective views showing cores for a composite magnetic head obtained by cutting out from the combined joined body shown in FIGS. 13 and 14, respectively. 2: Ferrite block 4: Slit, 6: Resist film 8: Uneven surface, 10: Metal magnetic layer 12: Coil winding groove, 14: Combined bonded body 16: Gap, 18: Track width defining groove 20: Track, 22 : Non-magnetic material 24, 26: Core for composite type magnetic head 28: Magnetic gap

Claims (4)

[Claims] 1. A manufacturing method of a core for a magnetic head using a combination bonded body in which a pair of ferrite blocks are abutted to each other to form an annular magnetic path, and a gap having a predetermined gap is formed in the abutting portions of the ferrite blocks. In the method, a first step of depositing a resist on at least a gap forming portion of the abutting surface of at least one of the pair of ferrite blocks, and patterning the resist sequentially at a predetermined pitch in the track width direction, The second step of etching at least the gap forming portion of the abutting surface of the ferrite block through the uncovered exposed portion to form an uneven surface, and the etched abutting surface of the ferrite block,
A third step of depositing a predetermined metal magnetic material, a fourth step of removing at least a portion of the ferrite block to which the metal magnetic material has been deposited to a predetermined thickness to make it flat, and a fourth step Prior to or after the fourth step, a fifth step of forming a groove for coil winding on at least one butt surface of the pair of ferrite blocks, and the first step to the fifth step, A sixth step of forming a non-magnetic layer having a predetermined thickness on at least the gap forming portion of the abutting surface of at least one of the pair of ferrite blocks, and the gap of the abutting surface of the pair of ferrite blocks after completion of the sixth step. A seventh step of obtaining the combined joined body by making the forming portions face each other and joining them to each other, and forming a track width defining groove and a gap in the combined joined body. The eighth step of forming in the intersecting direction, the ninth step of burying a predetermined non-magnetic material in the groove for defining the track width, and the combined bonded body in which the non-magnetic material is embedded at a predetermined position. And a tenth step of obtaining at least one core for a composite magnetic head, the method for manufacturing a core for a composite magnetic head. 2. The etching shape in the gap forming portion of the ferrite block formed in the second step is a shape having no parallel portion with respect to the gap forming surface. Manufacturing method. 3. In the eighth step, when a groove for defining a track width is formed, a resist is applied in a state where a groove forming portion of the combined assembly of the ferrite blocks is exposed, and then etching is performed. The manufacturing method according to claim 1 or 2, wherein the groove is formed thereby. 4. When forming a groove for defining a track width in the eighth step, by irradiating the groove forming portion of the combined assembly of the ferrite blocks with a laser, or in a reaction solution or a reaction gas. The manufacturing method according to claim 1 or 2, wherein a desired groove is formed by irradiating with a laser.