JPS62202304A - Manufacture of magnetic head - Google Patents

Abstract

PURPOSE:To form a uniform gap over the entire length by applying ion beam etching to a ferrite wafer so as to form a gap slot whose bottom shape is not in parallel with a gap counter face and forming a ferromagnetic metallic film onto the gap slot only by the thin film forming process. CONSTITUTION:The gap slot 20 is formed by the ion beam etching process so that the bottom of the gap slot 20 of a couple of magnetic core halves 1a, 1b made of a ferromagnetic oxide is not in parallel with the gap counter face 14. Then the ferromagnetic metallic film 21 is formed in the gap slot 20 by the thin film processing and a couple of the magnetic core halves 1a, 1b are butte to form a magnetic gap 5. Since the ferromagnetic metallic film 21 is formed by the coating of a metal mask 18, no ferromagnetic metallic film 21 is stuck to the gap counter face 14 of a ferrite wafer 11 except the gap slot 20 thereby reducing the effect of the stress on the ferrite wafer 11.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method of manufacturing a magnetic head, and in particular to a method of manufacturing a magnetic head suitable for use in a small magnetic recording/reproducing device.
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[Technical background of the invention and its problems] In recent years, as magnetic recording and reproducing devices such as video tape recorders have become smaller and more sophisticated, higher recording densities have been required. Various types of magnetic heads have been proposed to meet this requirement, each having a narrow track and a high saturation magnetic flux density. For example, as shown in FIG. 10, a pair of magnetic cores Ia and lb made of ferrite have gap facing surfaces 2a.
, 2b and the glass filling grooves 3a, 3b using vacuum thin film forming technology such as sputtering.
Ferromagnetic metal films 4a and 4b such as amorphous are formed. A magnetic head is constructed by abutting these half cores la and ib through a nonmagnetic thin film to form a magnetic gap 5, and bonding them with molten glass 6a and 6b. However, in the magnetic head having this structure, the boundary surfaces 7a and 7b between the ferromagnetic metals 1114a and 4b and the half cores la and lb move as pseudo gaps, which adversely affects the reproduced output signal. In order to solve this problem, as shown in FIGS. 11, 12 and 13, the boundary surfaces 8a to 8d, 9a, 9b and 10a, 1
A magnetic head in which each of the magnetic heads 0b is formed non-parallel to the gap 5 has been proposed.

By the way, in order to make the completed magnetic head more compact,
The shape of ferrite wafers serving as substrates tends to be thinner. Therefore, as shown in FIG. 14, half core la, 1
The flatness of the ferrite wafer 11 made of the material b is easily affected by the machining of the ferromagnetic metal film forming grooves 12, and after machining, a warp ω occurs in which the grooved surface 13 becomes concave. Since the ferromagnetic metal film 4 is formed after roughly processing the grooves 12, the wafer is subjected to stress during cooling after film formation due to the difference in thermal expansion coefficient between the ferrite and the film material, and the warp ω becomes roughly large. Furthermore, at this time, the ferromagnetic metal film 4 is also deposited on the gap facing surface 14 other than the inner surface of the groove 12.
This has an even greater influence on warpage ω.

In this case, since the ferromagnetic metal film 4 is usually formed in plasma, a temperature rise is unavoidable, and the ferrite wafer 11
It is not possible to correct the warpage ω of the glass base and then paste it onto a flat surface such as another glass base. Thereafter, both sides of the ferrite wafer 11 are usually lapped with alumina powder or the like in order to remove the excess ferromagnetic metal 11!4 and at the same time remove the above-mentioned warpage. However, in this case, as shown in FIG. 15, due to the difference in lapping workability, the warp ω is removed only on the grooved surface 13, and the unprocessed surface 1
5, the warp ω is hardly removed. This can be prevented by increasing the load on the ferrite wafer 11 during the lapping process to correct the warping, but this is not preferable because it will cast a shadow on the formed ferromagnetic metal film 4 and cause peeling. do not have. As a result, as shown in FIG. 16, in the ferrite wafers 11a and 11b, even if the pressure P is increased during gap bonding, uneven gaps 16 are likely to be formed over the entire length of the wafer 11. For this reason, it is necessary to attach the ferrite wafer 11 to another flat surface such as a glass base while correcting the warpage before bonding the gap bond, and then to add processing such as one-sided lapping to make both sides parallel, which slows down the process. There was a problem in that the number of units of processing increased and the number of processing units had to be reduced.

Furthermore, as mentioned above, as shown in FIG.
It is formed not only on the inner surface of the gap but also on the gap facing surface 14. Therefore, as shown in FIG.
This also affects the ferrite wafer 11 on the inner surface of the ferrite wafer 11, resulting in the problem of generating cracks 17 within the ferrite wafer 11. The reason for this is, as mentioned above, the ferromagnetic gold on the gap facing surface 14 due to the lapping process. This is because the removal of I4 causes the previously balanced stress inside the metal film 4 to become unbalanced, causing the ferrite wafer 11 near the interface to lose its resistance. If this crack 17 occurs, the ferromagnetic metal 1114 will peel off in most cases during machining in the subsequent process, resulting in a decrease in yield.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a method for manufacturing a magnetic head that can form a uniform gap over the entire length of a ferrite wafer with a small number of man-hours and a high yield. do.

[Summary of the Invention] The present invention comprises a step of forming a gap groove by ion beam etching so that the bottom surface of the gap groove in a pair of magnetic core halves made of a ferromagnetic compound is non-parallel to the surface facing the gap; A magnetic head is manufactured by forming a ferromagnetic metal film in the gap groove by thin film processing, and forming a magnetic gap by butting the pair of magnetic core halves, and creating a uniform gap. It is designed so that it can be formed.

[Embodiments of the Invention] Hereinafter, an embodiment of a method for manufacturing a magnetic head according to the present invention will be described with reference to the drawings.

1 to 8 show manufacturing steps according to an embodiment of the present invention. In these figures, the same or equivalent parts as those of the conventional example shown in FIGS. 10 to 16 are denoted by the same reference numerals. First, as shown in FIG.
is covered with a metal mask 18 and fixed tightly. This metal mask 18 is formed with a slit window 18a having a width approximately equal to the recording/reproducing track width after the magnetic head is completed.

In this case, it is desirable that the surface of the ferrite wafer 11 be finished with as little surface roughness as possible, so that the metal mask 18 can be brought into close contact with the ferrite wafer 11. Further, in both the ion beam etching and sputtering steps described later, it is possible to prevent the beam from going around between the ferrite wafer 11 and the metal mask 18 and colliding with the area larger than the slit 18a. The metal mask 18 is made of a material such as titanium alloy that has an extremely low etching rate with respect to the ion beam, and as shown in FIG. It is approximately equal to the magnetic head track width TW. The opening angle θ of the slit 18a and the thickness t of the metal mask 18 are such that the ion beam Ib incident on the metal mask 18 from an oblique direction is blocked and the ferrite wafer 1
Create a shadow part S on a part of 1.

This greatly affects the bottom shape of the gap groove formed by the ion beam Ib. For this reason, slit 18
Regarding the handling of a, the angle θ and the thickness t of the metal mask 18 must be selected so that the curvature of the bottom surface is as small as possible. As a means for this, for example, as shown in FIG. 3, by performing ion beam etching with the ferrite wafer 11 fixed on the surface of the oscillating body 19 in a vacuum apparatus, the incident angle of the ion beam Ib can be changed continuously. to change. As a result, as shown in FIG. 4, a gap groove 20 having a slightly shallower bottom shape at the center is formed.

Next, a ferromagnetic metal film 21 having a high saturation magnetic flux density such as sendust or amorphous is deposited in the gap groove 20 by a thin film forming method such as sputtering in a vertical direction on the ferrite wafer 11 still covered with the metal mask 18 . Then, as shown in FIG. 5, by removing the metal mask 18, a ferromagnetic metal film 21 is formed only within the gap groove 20. Finally, as shown in FIG. 6, glass filling grooves 22a, 22b for regulating track width and grooves 23 for coil winding windows are formed in the conventional manner, and the ferrite wafer is
, llb, and then melted and filled with glass 24 in a high temperature furnace to form both wafers 11a.

Glue the tib. A magnetic gap 5 is thereby formed and cut at a desired azimuth angle to complete the magnetic helad core shown in FIGS. 7 and 8.

According to this embodiment, the ferrite wafer 11 after forming the gap groove 20 for forming the ferromagnetic metal 121
The stress remaining in the substrate can be sufficiently reduced compared to when the substrate is formed by conventional machining. Therefore, processing can be performed without causing warping of the ferrite wafer 11 due to this stress. Furthermore, since the ferromagnetic metal film 21 is formed by covering it with the metal mask 18, the ferromagnetic metal film 21 does not adhere to the gap facing surface 14 of the ferrite wafer 11 other than the gap groove 20. Therefore, the stress caused by the difference in thermal expansion coefficient between ferrite and ferrite and a ferromagnetic metal such as sendust or amorphous becomes small, and the influence of stress on the ferrite wafer 11 can be reduced.

As a result, the ferrite wafer 1 as seen in the conventional example
It is possible to reduce the warpage of 1, and it is possible to finish the product with a constant thickness. Then, it becomes easy to make the thickness constant over the entire gap length during gap bonding.

In addition, the ferromagnetic metal film, which could conventionally be formed only on a very limited part of the ferrite wafer 11, can be formed over a wide range by shaking the ferrite wafer 11.
The yield of magnetic Rad chips obtained from the paired ferrite wafers 11 can be improved. Furthermore, in the past, after forming the ferromagnetic metal film 4, a process such as double-sided lapping of the ferrite wafer 11 was required, but the thickness of the metal film 21 to be formed is controlled to match the depth of the gap groove 20. Then, the gap facing surface 1 before gap bonding
There is no need to perform processing such as lapping other than the mirror finishing described in step 4, and the number of man-hours can be reduced. Furthermore, as a result, cracks occurring on the surface of the ferrite core 11 can be suppressed, and peeling of the ferromagnetic metal film 21 can be prevented, thereby increasing the yield of magnetic herad chips.

In this embodiment, the case where the surface roughness of the ferrite core 11 is made as small as possible in order to improve the adhesion between the ferrite core 11 and the metal mask 18 has been explained.
A similar effect can also be obtained by coating the surface of the ferrite wafer 11 with caulking photoresist 25 as shown in the figure.

[Effects of the Invention] As described above, according to the present invention, ion beam etching is performed on a ferrite wafer to form a gap groove whose bottom shape is non-parallel to the surface facing the gap,
Next, since the ferromagnetic metal film is formed only in the gap groove by thin film forming processing, a uniform gap can be formed over the entire length of the ferrite wafer with a small number of man-hours and a high yield.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 6 are diagrams showing manufacturing steps according to an embodiment of the method for manufacturing a magnetic head according to the present invention. FIGS. 1 and 6 are perspective views, and FIGS. 5 to 5 are front views, and FIG. 7 is a perspective view of the magnetic herad tip manufactured according to this example. 8 is an enlarged plan view of the main part of FIG. 7, FIG. 9 is a front view showing another embodiment of the present invention, and FIGS. 10 to 13 are perspective views showing a conventional magnetic head chip, respectively. 14 to 18 are diagrams showing problems in the manufacturing process of conventional magnetic head chips, and FIGS. 14 and 15 are perspective views, and FIG.
Figures 1 to 18 are front views. la, lb...magnetic core 2a, 2b, 14...
・Gap facing surfaces 4a, 4b, 21...Ferromagnetic metal film 5...Magnetic gap 12.20...Gap groove 18...Metal mask 18a...Slit window Patent attorney Noriyoshi Kon Right Figure 1, Figure 2, lb Figure 3, Figure 6, Figure 7, Figure 8, Figure 11, Figure 12, Figure 13, Figure 14, Figure 15, Figure 16

Claims (3)

[Claims] (1) A step of forming a gap groove by ion beam etching so that the bottom surface of the gap groove of a pair of magnetic core halves made of ferromagnetic oxide is non-parallel to the surface facing the gap, and 1. A method of manufacturing a magnetic head, comprising the steps of forming a ferromagnetic metal film by thin film processing, and abutting a pair of magnetic core halves to form a magnetic gap. (2) The method of manufacturing a magnetic head according to claim 1, wherein the ion beam etching process is performed while swinging the magnetic core half through a metal mask in which a slit window is formed. (3) A method for manufacturing a magnetic head according to claim 1 or 2, characterized in that the ferromagnetic metal film is formed through a metal mask.