JPH03225607A - Magnetic head and its production - Google Patents

Abstract

PURPOSE:To greatly improve the yield of a magnetic head by forming grooves at both side edges in the track width direction of the track width parts near the surface for sliding with magnetic recording medium of the butt surfaces of magnetic core half bodies and forming ferromagnetic metallic thin films in the regions exclusive of the grooves of the butt surfaces. CONSTITUTION:After the track grooves 4 are formed on the butt surfaces of the ferrite plates 1, the ferromagnetic metallic thin films 3 are formed thereon. A winding groove 7 is formed on one of the ferrite plates 1. The straight grooves 9 of a narrow width are formed on the butt surface of the ferrite plate 1 along the respective bottoms of the track grooves 4. The thin films 3 are removed in the parts of the grooves 9 and the grooves are later formed to the length arriving at a winding groove 7 from the surface 10 for sliding with the media and the surface to be worked. The ferrite plates 1, 1' are then butted against each other via the magnetic gap 6 and low melting glass 8 is packed into the grooves 4, 9, by which the plates are joined. The sliding surface 10 is subjected to cylindrical grinding and the block is cut at cutting lines A-A', B-B' at a core width W. Since the metallic thin films 3 are not cut in the part near the surface for sliding with the media, the strains and cracking occurring in a difference in coefft. of thermal expansion between the thin films 3 and the ferrite part are not generated.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an inductive magnetic head that magnetically records or reproduces information by bringing a magnetic core into sliding contact with a magnetic recording medium, and a method for manufacturing the same. It is something.

[Prior Art] In recent years, magnetic recording and reproducing devices such as VTRs (video tape recorders) and DATs (digital audio recorders) have been increasing their recording densities. Metal tapes made of ferromagnetic metals and their alloys have come into use. Since this type of magnetic recording medium has a high coercive force Hc, the magnetic core material of the magnetic head used for recording and reproducing must have a high saturation magnetic flux density Bs. However, the ferrite material conventionally used as magnetic core material has a low saturation magnetic flux density, and permalloy cannot be used because it lacks wear resistance. A so-called metal-in-gap type magnetic head has been proposed in which a ferromagnetic metal thin film of sendust, amorphous, or the like is formed on the abutting surfaces by vacuum thin film formation technology.

A conventional example of the magnetic core of this type of magnetic head is shown in FIGS. The magnetic core is constructed by joining them by glass welding. The main body of the magnetic core half 2.2゛ is M n -Z
Made of a ferromagnetic oxide such as n-ferrite, a ferromagnetic metal thin film 3 is formed using vacuum thin film formation technology on the abutting surfaces of which are formed inclined track grooves 4 that regulate the track width of the magnetic gap 6. There is. The track groove 4 is filled with low melting point glass 8. Then, a coil winding (not shown) is wound around the magnetic core through the winding groove 7 formed in one of the magnetic core halves 2 to form a magnetic head.

Next, a method of manufacturing this magnetic core will be explained with reference to FIGS. 5(A) to 5(E).

In FIG. 5(A), the symbol l is the magnetic core half 2.2.
In the manufacturing process of the 6 magnetic core, which is a ferrite plate that is the base material of 2 and is formed into a rectangular shape from ferrite, which is a ferromagnetic oxide, the ferrite plate 1 shown in Fig. 5 (A) is first punched through a magnetic gap. A track groove 4 for regulating the track width T is formed on the abutting surfaces (upper surface in the figure) to be matched.

The track groove 4 has a V-shaped cross section.

Next, as shown in FIG. 5(B), a ferromagnetic metal thin film 3 is formed on the entire surface of the abutting surfaces of the ferrite plates 1 by a vacuum thin film forming technique such as vapor deposition or sputtering. Then, two ferrite plates (2) on which the film has been formed are prepared, and a winding groove 7 is formed on the abutting surface of one of them as shown in FIG. 5(C).

Next, as shown in FIG. 5(D), the ferrite plate 1 of FIG. 5(C) and the ferrite plate l° of FIG.
The ferrite plate 1.1' is joined by glass welding.

Next, as shown in FIG. 5(E), the front surface of the assembled ferrite plate 1.1' in the figure is attached to the magnetic recording medium sliding surface (hereinafter referred to as
After cylindrical grinding as 10 (abbreviated as “medium sliding surface”), the symbol A
, A', B, and B', the joined body of the ferrite plates 1.1' is cut by slicing at a predetermined core radius W, to obtain the magnetic cores shown in FIGS. 3 and 4.

[Problems to be Solved by the Invention] However, in the conventional example described above, when the joined body of the ferrite plates 1.1' shown in FIG. 5(E) is cut by slicing in the manufacturing process, the ferrite plates l.

Since the ferrite part of LO and the ferromagnetic metal thin film 3 are cut at the same time, the distortion that occurred due to the difference in thermal expansion coefficient between the ferrite part and the ferromagnetic metal thin film 3 during the previous glass welding of the low melting point glass 8. is opened, and as a result, a crack is formed in the ferrite portion as shown by the symbol ll in FIG.
There were cases where this occurred along the lines of

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure and manufacturing method that can prevent the above-mentioned cracks from occurring in the magnetic core of a metal-in-gap type magnetic head.

[Means for Solving the Problems] In order to solve the above-mentioned problems, according to the present invention, a pair of magnetic core halves are abutted against each other through a magnetic gap and joined by glass welding, and a strong material is attached to the abutting surfaces of the core halves. In a magnetic head having a magnetic core on which a magnetic metal thin film is formed, grooves are formed on both edges in the track width direction of at least a portion near the magnetic recording medium sliding surface of the abutting surfaces of the magnetic core halves, and The magnetic metal thin film is formed in a region other than the groove on the abutting surface.6 Also, according to the present invention, in the method for manufacturing a magnetic head, the magnetic metal thin film is formed after the base material of the magnetic core half through the magnetic gap. A step of forming a film of ferromagnetic metal thin film II on the abutting surfaces to be matched, a step of abutting the pair of base materials on which the films have been formed through a magnetic gap and joining by glass welding, The method includes the step of cutting the bonded body of the above-mentioned upper materials to a predetermined core width to obtain a magnetic core, and between the film forming step and the bonding step, at least the magnetic core of the abutting surface of the materials is transferred to the recording medium by sliding. A configuration was adopted in which a step of forming a groove in a portion near the surface to be cut in the cutting step was performed.

[Function] According to the above-described structure and configuration, at least the medium sliding of the abutting surfaces of the joined body is cut when the joined body of the barring material of the magnetic core halves is cut into a predetermined core width in the manufacturing process of the magnetic core. Since the ferromagnetic metal thin film is not cut in the area near the surface, cracks can be prevented from forming at least in the area near the medium sliding surface of the magnetic core obtained by cutting.

[Example] Hereinafter, details of embodiments of the present invention will be described with reference to the drawings.

1 and 2 (A) to (F) illustrate the structure and manufacturing method of the magnetic core of the metal-in-gap type magnetic head according to the embodiment of the present invention. Components common or corresponding to those in FIGS. 3 to 5 are given the same reference numerals, and explanations of the common components will be omitted.

First, FIG. 1 shows the structure of the magnetic core of this embodiment.

The basic structure of the magnetic core shown in the figure is the same as that of the conventional example, in which a track groove 4 is formed on the abutting surfaces of the magnetic core halves at an angle of 2.2 degrees, and a ferromagnetic metal thin film 3 is formed on top of the track groove 4. However, in this embodiment, a full 9 is formed on both edges of the magnetic core in the track width direction at a portion near the medium sliding surface of the 2.2° abutting surface of the magnetic core halves (front end in the figure). The ferromagnetic metal thin film 3 is formed in a region other than the groove 9 on the abutting surfaces. Groove 9 communicates with track groove 4, and both grooves 4.9 are filled with low melting point glass 8. The structure of other parts of the magnetic core of this embodiment is the same as that of the conventional example.

Next, the manufacturing process of the magnetic core of this example is shown in FIGS.
This is explained by F).

The steps of this embodiment shown in FIGS. 2(A) to 2(C) are common to the conventional example, and the ferromagnetic metal thin film 3 is formed after the track grooves 4 are formed on the abutting surfaces of the ferrite plates 1. ,
Two of the ferrite plates 1 are prepared, and one of them has a winding groove 7.
form.

Next, in a process different from the conventional one, as shown in FIG. 2(D), a narrow straight line 9 is cut along the bottom of each track groove 4 on the abutting surface of the ferrite plate l on which the winding groove 7 is formed. Form. The depth of the groove 9 is significantly larger than the thickness of the ferromagnetic metal thin film 3, and the ferromagnetic metal thin film 3 is removed at the groove 9 portion. Note that here, the length 9 is a length that reaches the winding groove 7 from the surface of the ferrite plate 1 that will be later processed as the medium sliding surface 10. Further, although not shown, the abutment surface of the ferrite plate 1 in FIG. 2(B) on which the winding groove 7 is not formed is similarly formed with 9.

Next, a pair of ferrite plates 1 formed with full 9 as described above.
are butted together through a magnetic gap 6 as indicated by the symbol l and 1° in FIG.
The groove 9 is filled with the glass and the ferrite plates 1 and 1 are welded.
Join o.

Next, as shown in FIG. 2(F), the medium sliding surface 10 of the joined body of the ferrite plate 1 and lo is cylindrically ground, and then the cutting lines A-A'B-B' passing through the respective grooves 9 are cut. The magnetic core shown in FIG. 1 is obtained by cutting the joined body along the line to a predetermined core width W.

According to this embodiment as described above, when cutting the joined body of ferrite plates 1.1' shown in FIG. 2(F) at a predetermined core width W, cutting lines AA' and B- The cut surface of the bonded body along B° is a groove 9 on which the ferromagnetic metal thin film 3 is not formed.
The ferromagnetic metal thin film 3 is not cut in the area near the medium sliding surface of the abutting surface of the magnetic core halves 2.2 degrees of the magnetic core obtained by this cutting, so the ferromagnetic metal thin film 3 is not cut in the area near the medium sliding surface of the magnetic core. This can prevent the generation of cracking force due to the release of strain caused by the difference in thermal expansion coefficient between the ferromagnetic metal thin film 3 and the ferrite portion.

Actually, the sample of the magnetic core of this example was M n −Z
From n-ferrite, the track width is 20 μm, the depth of the track groove 4 is 0.2 mm, and the width is 0.4 mm.

Core width 80 μm, ferromagnetic metal thin film 3 is Fe-Al-5i
Alloy film thickness 10LLm, groove 9 width 0.35mm, depth 0
．． Although 100 chips were manufactured with a size of 4 mm, not a single crack occurred. On the other hand, 100 chips were manufactured as samples of the conventional example with the same specifications except that the groove 9 was not processed, but cracks had occurred in 83 of them. According to this embodiment, by eliminating cracks in the magnetic core, which conventionally occur at a very high rate, the yield of magnetic heads can be greatly improved and costs can be reduced.

In addition, in the above, full 9 is from the medium sliding surface of the magnetic core to the winding groove 7.
However, the magnetic core may be formed over the entire length of the magnetic core from the medium sliding surface to the opposite end surface, and the dimension of 9 is not particularly limited.

[Effects of the Invention] As is clear from the above description, according to the present invention, a pair of magnetic core halves are abutted against each other through a magnetic gap and joined by glass welding, and a ferromagnetic metal thin film is formed on the abutting surfaces of the core halves. In a magnetic head having a magnetic core in which a film is formed, a ferromagnetic metal thin film is formed on both side edges in the track width direction of at least a portion near the magnetic recording medium sliding surface of the abutting surfaces of the magnetic core halves, and the ferromagnetic metal thin film In the manufacturing method of the magnetic head, a ferromagnetic metal is formed on the abutting surfaces that are abutted through the magnetic gap after the base material of the magnetic core halves. a step of forming a thin film, a step of abutting the pair of base materials on which the film has been formed through a magnetic gap and joining them by glass welding, and bonding the bonded body of the base materials obtained through the step to a predetermined core. a step of cutting the width to obtain a magnetic core, and between the film forming step and the bonding step, at least a portion of the abutting surface of the base material near the magnetic recording medium sliding surface is cut in the cutting step. Since a configuration is adopted in which a step of forming grooves is performed, it is possible to prevent the generation of cracks in the magnetic core during the manufacturing process, greatly improving the yield of magnetic heads, and achieving the excellent effect of reducing costs.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of a magnetic core of a metal-in-gap magnetic head according to an embodiment of the present invention, and FIG.
A) to (F) are explanatory diagrams of the manufacturing process of the same magnetic core, and FIGS. 3 and 4 are perspective views showing the structure of the magnetic core of a conventional metal-in-gap type magnetic head and the medium sliding surface, respectively. 5A to 5E are respectively explanatory views of the manufacturing process of the same magnetic core. 1, lo-ferrite plate 2.2゛--magnetic core half 3--ferromagnetic metal thin film 4--track groove 6--magnetic gap 7--winding groove 8--low melting point glass 9・・・Mizoen ν6zue's Gun Eizoki Figure 1 Figure 2 Figure A Figure 3 Figure 4 Figure 5 Figure 1 Flying Japan-Japanese Federation Figure 5

Claims (1)

[Claims] 1) A magnetic head having a magnetic core in which a pair of magnetic core halves are abutted against each other through a magnetic gap and joined by glass welding, and a ferromagnetic metal thin film is formed on the abutting surfaces of the core halves. Grooves are formed on both edges in the track width direction of at least a portion near the magnetic recording medium sliding surface of the abutting surfaces of the magnetic core halves, and the ferromagnetic metal thin film is formed in an area other than the grooves of the abutting surfaces. A magnetic head characterized in that a film is formed. 2) A step of forming a ferromagnetic metal thin film on abutting surfaces of the base materials of the magnetic core halves that are abutted against each other through a magnetic gap, and a step of abutting the pair of base materials on which the film has been formed through a magnetic gap. The method includes a step of joining by glass welding, and a step of cutting the joined body of the base materials obtained in the step to a predetermined core width to obtain a magnetic core. 1. A method of manufacturing a magnetic head, comprising the step of forming a groove at a portion of the abutting surfaces of the materials, at least in the vicinity of the magnetic recording medium sliding surface, to be cut in the cutting step.