JPH0467246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic head for recording and reproducing using a metal magnetic material.

[Prior art]

Conventionally, magnetic heads using ferrite as the magnetic material constituting the magnetic head core have been put into practical use. The magnetic head made of ferrite material is
It is widely used as a video head for VTRs because it has high magnetic permeability, high playback efficiency, and excellent wear resistance. However, in recent years, with the demand for higher performance, smaller and lighter VTRs, the holding power of magnetic tapes has been shifting from the conventional 500 to 600 oersted (oxide tape) to 1200 to 1500 oersted (metal tape). When the coercive force of a magnetic tape increases in this way, recording becomes insufficient with conventional ferrite (saturation magnetic flux density of approximately 5000 Gauss). On the other hand, magnetic heads that use metallic magnetic materials such as sendust (Fe-Al-Si alloy) or amorphous magnetic alloys as other magnetic materials constituting the magnetic head core material have a saturation magnetic flux density higher than that of ferrite. It has excellent properties such as high coercivity, sufficient recording capability even on the high coercive force metal tape, and low sliding noise. However, the core thickness of the generally used head shape has a lower effective magnetic permeability in the video frequency range than ferrite, and therefore the reproduction efficiency is lower. Furthermore, the biggest problem is that it has poor abrasion resistance.

Recently, in order to solve the above problem, a magnetic head has been proposed which combines a magnetic metal material having a thickness equal to the width of the track and a protective material having excellent wear resistance. For example, as shown in FIG. 1, protective materials 11 and 1
1' is provided (Japanese Unexamined Patent Publication No. 109613/1983). Here, 12 in the figure is a gap via a non-magnetic material, 1
3 is a window for coil winding. A joining block of such a magnetic head core is made by the process shown in FIG. In FIG. 2a, a metal magnetic material 10 with a thickness equal to the track width is formed on a protective material 11 by vapor deposition or sputtering, and the other protective material 11' is bonded on the surface of the metal magnetic material 10. , a joining block 14 as shown in FIG. 2b is obtained. At this time, the bonding material includes resin, glass, brazing material, etc. On the other hand, the protective material for the metal magnetic core material is selected from materials with low electrical conductivity, such as glass and ceramic, which have appropriately set wear resistance, coefficient of thermal expansion, workability, etc. However, when bonding these protective materials in combination with a metal magnetic material, the use of resin, glass, or brazing material has the disadvantage that one is easy to bond and the other is difficult to bond.
For example, resins can be joined relatively easily, but
It lacks reliability in terms of accuracy and humidity, and its biggest drawback is that resin seeps onto the surface while the tape is running. On the other hand, glass has a strong bonding strength with a protective material, but a weak bonding strength with metal. The opposite is true for brazed wood. Both methods have advantages and disadvantages when it comes to joining dissimilar materials, and are not fully satisfactory. Even if they are bonded via an intermediate film, the bonding strength is weak and problems such as peeling occur during processing, resulting in a poor processing yield.

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks and provide a structure of a magnetic head that has high bonding strength, excellent wear resistance, and excellent processing yield in a magnetic head that combines a metallic magnetic material and a protective material. It's about doing.

[Summary of the invention]

The present invention focuses on the fact that oxides such as glass and ceramic used for protective materials have high bonding strength with glass, and solves the problem by creating a head structure in which the main bonding portion is made on the surface of the protective material. did.

The present invention provides a magnetic head in which a main magnetic path forming surface of a metal magnetic material having the shape of a magnetic head is sandwiched between two protective substrates, in which a shallow groove is provided on at least one of the protective substrate surfaces and the groove is approximately equal to the track width. This is a magnetic head in which a thick metal magnetic material is embedded, and the main joint strength is formed by the joint between two protective substrates. A specific example is shown in FIG. That is, protective material 1
A shallow groove having a depth approximately equal to the track width is formed on at least one surface of the protective members 11 and 11', and the shallow groove is filled with a metal magnetic material 10, and the main bond between the protective members 11 and 11' is the protective member Comrade joint surface 15,
15'. The above joining block is divided into magnetic core halves 16 and 16' , and after forming a coil winding groove 13 in at least one core half,
The core halves 16 , 16' are joined to the gap abutting surfaces via a non-magnetic gap material to obtain a magnetic head core. At this time, the main bonding is similarly performed on the protective material surface, and a bonding reinforcing material may also be filled in a part of the coil winding window or the rear part of the core.

The characteristics of the magnetic head structure and the manufacturing process thereof will be explained in detail below with reference to Examples.

[Embodiments of the invention]

FIG. 4 shows a first embodiment of the process for manufacturing the magnetic head of the present invention. A and the like indicating the process order correspond to A and the like in FIG. 4, respectively.

(a) Prepare the protective substrate 20 that forms one side of the magnetic head. The protective board is made of non-magnetic ceramic material, width a is the core width of about 3 mm, length b is the core height of about 2.5 mm (the length of the two pieces is shown), and thickness c is the core width. Approximately 1 at half the thickness
mm, each dimension including machining allowance. The upper surface 21 becomes a bonding surface with another protective substrate (described later). A shallow groove 22 is formed in the bonding surface 21 to be filled with a metal magnetic material. The shallow groove 22 is formed to be slightly deeper than the track width of the magnetic head, the groove width is made narrower than the core width, and the groove is processed so as to leave a bonding surface with the protective material. Processing is performed using a grindstone or mask etching.

(b) Next, a metal magnetic material such as sendust or an amorphous magnetic alloy 23 is formed in the shallow groove 22 by a thin film forming technique such as vapor deposition or sputtering.

(c) Next, the excess metal magnetic material generated in the above magnetic film forming step is removed by grinding, polishing, etc. to form a bonding surface. At this time, the thickness of the metal magnetic film is made approximately equal to the track width t, and the protective substrate surface is exposed on both end faces.

(d) Next, a glass 24 is provided on the polished surface (joint surface) by means such as sputtering.

(e) Next, stack the other protective substrate 20'.
It is desirable that the bonding surface of the protective substrate 20' be mirror-polished, and in some cases, a glass film may be formed on the polished surface as well to improve the bonding strength.

(f) Next, the overlapping protective substrates are heated while being pressed to form a bonded body 25 .

(g) Next, the above-mentioned joined body 25 is divided in the center to form a pair of core block halves 26, 26', and then the gap abutting surfaces 27, which are butted and joined again,
27' is mirror polished.

(h) Next, a groove 28 for coil winding is formed on at least one gap abutting surface. Thereafter, a nonmagnetic gap film is formed to a specified thickness on the gap abutting surfaces 27, 27' by sputtering. In this case, it is preferable to form a high melting point glass on the front abutting portion of the head core, and a low melting point glass to serve as a bonding material on the rear abutting portion.

(li) Next, the two core blocks 26, 26' are butted against each other and bonded together by applying pressure while heating to form the magnetic head core block 29. At this time, the strength can be increased by adding glass to part of the window as a reinforcing material. The strength of the main joints is ensured by the protective material joints 31, 31'. That is, since oxide-based protective materials have good wettability with glass and excellent bonding strength, problems such as peeling hardly occur during the processing process. Next, cut along the dotted line.
One head core 32 as shown in (J) is obtained.

Next, as shown in (Le), the core width T (approximately 150 μm)
Then, the head core chip 33 is completed.

Other embodiments of the present invention are shown in FIGS. 5 and 6. In the process, a shallow groove 22 is provided in the protective substrate 20 to be filled with a metal magnetic material. At this time, the end of the shallow groove is sloped, and azimuth loss is given so that the edge of the metal magnetic material filled in the shallow groove and the operating gap do not have a parallel part, so that the end of the metal magnetic material forms a pseudo gap. I am trying to prevent it from working as a. The angle θ of the inclined portion was in the range of 60° to 30°. The depth of the shallow groove was 30 μm. In the step, sendust alloy 23 is sputtered to the extent that the shallow grooves are filled.

In the process, unnecessary portions of the sendust alloy film were removed by grinding and polishing, and the thickness of the sendust film was defined to be a track width t (25 μm). The subsequent steps are performed by the steps shown in FIG. 4, and a head core having the structure of the tape sliding surface as shown in the steps is completed. Further, when producing a head core with a wide track width, it can be obtained by overlapping two blocks filled with sendust alloy films as shown in FIG.

Further, the sendust alloy film may be a single layer film, or may be a multilayer film with an insulating film interposed therebetween. In particular, in a head core with a wide track width, eddy current loss can be reduced so that high frequency characteristics do not deteriorate.

According to the present invention, since the operating gap g and the end of the metal magnetic body 23 do not form a parallel part, reproduction as a noise signal is eliminated.

Other embodiments of the invention are shown in FIGS. In FIG. 7, the track width is determined by the deposited thick film of metal magnetic material. That is, as shown in the process, a shallow groove provided in the protective substrate 20 is formed slightly deeper than the track width, a metal magnetic material is deposited on the shallow groove to a thickness equal to the track width, and then a non-magnetic protective material 3 is deposited on the shallow groove.
It has a structure in which 4 is deposited.

In the process, unnecessary non-magnetic protective material and metal magnetic material are removed by grinding and polishing. At this time, if the non-magnetic protective material is left, the thickness of the metal magnetic material becomes the track width, and thus the track width accuracy is improved.

〔Effect of the invention〕

According to the present invention, in a magnetic head in which the side surfaces of a metal magnetic material having the shape of a magnetic head are sandwiched between two protective substrates, at least one of the protective substrates is provided with a shallow groove, and the groove has a thickness approximately equal to the track width. The structure has a structure in which the main bonding strength is formed by the joint between the two protective substrate surfaces. The bonding strength with the glass used as the bonding material is increased, the problem of peeling during the head processing process is almost eliminated, and the head processing yield is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a conventional magnetic head, FIGS. 2a and b are block perspective views showing a method for manufacturing a conventional magnetic head, and FIG. 3 is a perspective view of a core showing an example of the magnetic head of the present invention. Figures 4 through 4 are perspective views and plan views for explaining the manufacturing process of the magnetic head of the present invention, and Figures 5 through 6 and 7 illustrate other embodiments of the present invention. FIG. 3 is a manufacturing process diagram of the magnetic head and a plan view of the tip of the head. 10, 23... Metal magnetic material, 11, 20... Protector, 22... Shallow groove for filling with metal magnetic material, 24...
Bonding material.

Claims (1)

[Claims] 1. In a magnetic head in which the main magnetic path forming surface of a magnetic layer forming at least a part of the magnetic path of the magnetic head is sandwiched between two protective substrates, a groove is provided in at least one of the protective substrate surfaces. A magnetic head characterized in that the above-mentioned magnetic layer is embedded in the groove. 2. The magnetic device according to claim 1, wherein the end of the groove of the protective substrate is inclined, and the edge of the magnetic layer provided in the groove has no part parallel to the operating gap. Head. 3. The magnetic head according to claim 1, further comprising a nonmagnetic film on the magnetic layer provided in the groove. 4. The magnetic head according to claim 1, wherein the magnetic layer is formed by laminating different types of films.