JPH03141006A - Composite type magnetic head - Google Patents

Abstract

PURPOSE:To exactly prescribe the track width by allowing the width of the upper face of thin film of a magnetic material provided on an abutting part of magnetic head half bodies to coincide with the track width, and forming both side faces so as to be led to the joint surface to the lower magnetic half body, while widening gradually the width from both ends of the upper face. CONSTITUTION:On an abutting part of at least one magnetic head half body 2 of a pair of magnetic head half bodies 2, 2 consisting of a high specific resistance magnetic material, a thin film 3 of a magnetic material having higher saturation magnetic flux density than this magnetic material is provided, and between the thin film 3 and the other magnetic head half body 2, a magnetic void part being parallel to the abutting part is formed. As for the thin film 3, the upper face opposed to the magnetic void part has high flatness and it is formed to width which coincides strictly with track width W, and both side faces 30 of the thin film 3 are widened gradually as to width from both ends and reach the joint surface to one magnetic head half body 2. Width T joined to its joint surface is formed so as to become larger than the track width W, therefore, a magnetic path is formed effectively without deteriorating the magnetic flux density on the upper face of the thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head used in a magnetic recording and reproducing apparatus.A composite magnetic head shown in FIG. 6 has been proposed as a magnetic head for use in a magnetic recording and reproducing apparatus such as a VTR (
Utility Model Application Publication No. 56-174119). This is because the abutting surfaces of a pair of magnetic head halves (2) (2) made of a high resistivity magnetic material such as a ferrite material are coated with a magnetic material having a higher saturation magnetic flux density than the magnetic material, such as sendust.
Thin films such as permalloy and amorphous magnetic materials (3) (3)
This increases the saturation magnetic flux density near the magnetic gap.

In the conventional composite magnetic head, even if the saturation magnetic flux density is increased by using a thin film such as sendust, the width T where the thin film (3) joins the bonding surface of the magnetic head half is the same as the target track width. In addition, since the magnetic head half is formed of a ferrite material, there is a risk that magnetic saturation may occur at the bonding surface.

Furthermore, conventional composite magnetic heads have had the following structural problems due to manufacturing methods. That is, in order to manufacture a composite magnetic head, as shown in FIG. A thin film (3) of Sendust, for example, is formed to a thickness of several μm on the abutting portion of the halves by a known film forming technique such as vacuum evaporation or sputtering.

The top surface of the thin film (3) is further coated with a non-magnetic layer of SiO* (
4) was formed to a thickness of about 0.1 μm using the same film-forming technique, and then the two block halves were butted together as shown in FIG. 3, and the track width regulating grooves (5) were filled with molten glass.
Combine both block halves.

Then, by slicing this to an appropriate thickness as shown in FIG. 4, a magnetic head (1) having the above-described non-magnetic layer (4) as a magnetic gap can be obtained.

However, in the film forming process of the above-mentioned manufacturing method, since sendust is vacuum-deposited or sputtered through a mask having slit-shaped openings at the abutting portions of both block halves, the state of adhesion of sendust particles is There was a difference between the area near the edge of the opening of the mask and the center of the opening, or the sendust particles entered the back side of the mask, resulting in an uneven film thickness, resulting in a product as shown in Figure 6. The Sendust thin film (3) of the composite magnetic head has rounded shoulders (3) at both ends.
1) (31) occurs. In such magnetic heads, the track width W cannot be accurately defined, which causes variations in recording and reproducing performance between products.

In addition, in order to solve the above problem, before forming track width regulating grooves in both block halves, films of sendust and sin were formed on the entire bonding surface, and then these films and the 7-elite wafer were simultaneously coated. Diamond blade or CBN
A method of forming the track width regulating groove (5) and the non-magnetic layer (4) by machining with a blade can also be adopted, but the thin film of sendust produced by this method sometimes peeled off during processing. . Of course, if the peeling area is large, it cannot be used as a product, but even if the peeling is slight, there may be a chipped part (32) as shown in Figure 6, and the above-mentioned flat shoulder Similar to section (31), the substantial track width W of the magnetic head is uncertain.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite magnetic head having a structure in which magnetic saturation is less likely to occur and variation in recording and reproducing performance between products due to uncertain track width can be reduced.

〔composition〕

The structure of the present invention is such that at least one of a pair of magnetic head halves (2) (2) made of a high resistivity magnetic material has a higher saturation than that of the magnetic material. A thin film (3) of a magnetic material having a magnetic flux density is provided,
A magnetic gap parallel to the abutting portion is formed between the thin film and the other magnetic head half. Said thin film (3)
The upper surface facing the magnetic gap has a high flatness and is formed to have a width that exactly matches the predetermined track width W, and both side surfaces (30) (30) of the thin film have a width that is smaller than the width from both ends of the upper surface. The thin film gradually expands and extends downward until it reaches the bonding surface with the one magnetic head half (2), and the width of the thin film bonding to the bonding surface of the one magnetic head half (2) is equal to the width of the thin film. It is characterized by being larger than the top surface.

[For production]

Even if the width of the upper surface of the thin film (3) facing the magnetic gap is narrowed to reduce the track width W, the magnetic field on the upper surface of the thin film is small because the thin film is made of a high saturation magnetic flux density material. There is very little chance of saturation occurring. Also, the radius T where the thin film (3) joins the bonding surface of the magnetic head half is the track width W.
Since the magnetic head half is formed larger than the above-mentioned thin film, a magnetic path is effectively formed in the magnetic head half without reducing the magnetic flux density on the upper surface of the thin film.

Further, since the thin film (3) has a high flatness at the upper surface and both side surfaces extend substantially perpendicularly to the upper surface, the track width W can be accurately defined.

[Special effects]

In the composite magnetic head according to the present invention, since the magnetic path is effectively formed, magnetic saturation is less likely to occur, and since the track width can be accurately defined, variations in recording and reproducing performance between products can be avoided. reduce

The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is an enlarged plan view of the vicinity of the magnetic gap of the composite magnetic head according to the present invention, showing a pair of magnetic head halves (2) made of ferrite material with track width regulating grooves (5). ) A thin film of Sendust (Fe-AX-Si alloy), which is a high saturation magnetic density material, is placed on the butt part of (2) (3)
(3) is provided, and a non-magnetic layer (4) of SiO is further provided between both thin films to form a magnetic gap parallel to the abutting portion. Further, the track width regulating groove (5) is filled with glass. The above Sendust thin film (3)
The non-magnetic layer (4) is formed by machining and stitching as described later to achieve the desired shape according to the present invention.

2 to 5 show the steps for manufacturing a composite magnetic head according to the present invention.

Figure 2 shows a block in which sendust thin films (3) (3) are provided at the abutting portions of a pair of ferrite wafers (20) (20) in which U-shaped grooves (21) are formed to serve as track width regulating grooves. A situation in which halves (11) and (12) are formed is shown. Note that a coil groove (13), which will later become a coil winding hole (8), is formed in one of the 7-elite wafers (20).

FIG. 5 shows the procedure for forming a thin film (3) of sendust on a ferrite wafer (20) by etching, which is a known technique. First, as shown in FIG. ! [(3) is formed to a thickness of about 1 to 10 μm by a film forming method such as sputtering.
A band-shaped corrosion-resistant layer (6) having a width W defined by the track width W is repeatedly formed on the top surface at a constant pitch. The strip-shaped corrosion-resistant layer (6) is formed by coating a dichromate-based photosensitive liquid on the surface of a thin film of Sendust to a thickness of about 1 μm and drying it, and then forming a slit-like opening with a width W.
It is formed through an exposure process in which an otomask is placed on it and irradiated with ultraviolet rays, and a development process in which the portions not covered by the original plate are removed using a developer.

Next, as shown in Figure 5(b), a thin film of sendust (3)
The portions not covered by the corrosion-resistant layer (6) are dissolved with an etching solution. In this example, a 30% nitric acid solution was used at 25° C. as an etching solution. On this occasion.

Corrosion progresses not only in the depth direction but also in the lateral direction, that is, below the corrosion-resistant layer (6), resulting in so-called side etching. It has been confirmed that the reproducibility is good. Therefore, it is possible to predict the amount of side etching in advance and determine the width W of the corrosion-resistant layer (6) that will provide the desired track width W. For example, the thickness of Sendust thin film (3) is 10μ
m, and if etching is performed for 6 minutes and 30 seconds using the above etching solution, the side etching amount will be about 8 μm. In the case of this embodiment, the track width W is 24±.

It is necessary to set the width W to 2 μm, and for this purpose, the width W of the corrosion-resistant layer (6) may be set to 40 μm.

In this example, this side etching is used to make Sendust thin 1! (3) is the desired cross-sectional shape.

That is, the side etching progresses further in the part of the sendust film near the corrosion-resistant layer (6), and as a result, as shown in the figure, the radius T of the bonding surface of the thin film (3) with the ferrite wafer (20) after molding is lower than that of the upper surface. It becomes larger than the radius W.

Also, the side surface (30) of the thin film (3) is approximately 90 degrees from the top surface.
Be moderate.

After the etching is completed, as shown in FIG. 5(C), a U-shaped groove (21) which will become a track width regulating groove is formed in the ferrite wafer (20) using a diamond blade. In this case, the blade is Sendust Thin 11! (3) It is necessary to form the Sendust thin film (3) as close as possible within the i range without touching it, but compared to forming a Sendust thin film or ferrite wafer only by machining, it is possible to form a Sendust thin film (3) with rough processing. ) is further coated with S by the same film-forming technique as described above.
A thin film of tOs is formed as a non-magnetic layer (4) for defining the gap length.The non-magnetic layer (4) is made of Sendust thin film 111 at the stage shown in FIG. 5(a). (3) is formed on the entire surface of the non-magnetic layer, and at the stage shown in FIG. It can also be molded into any shape.

Two block halves (11) (1) formed as above
2) are brought into contact with a non-magnetic material layer (4) as shown in Fig. 3, the track width regulating groove (5) is filled with molten glass, and both block halves are bonded and integrated. Body layer (4
), a track width regulating groove (5), and a coil winding hole (8).
) is completed. If you slice this into appropriate thickness,
A plurality of composite magnetic heads (1) shown in FIG. 4 are obtained.

As shown in FIG. 1, the sendust thin film (3) of the magnetic head (1) manufactured in this manner has an upper surface with high flatness, a side surface (30) extending approximately perpendicularly from the upper surface, and It has a joint surface with the magnetic head half having a width larger than the upper surface, and there are no rounded shoulders due to non-uniform film formation or gaps due to machining.

In the above-mentioned embodiment, all of the sendust thin film is formed by etching, but it is also possible to form only the upper layer of the thin film by etching and simultaneously form the remaining lower layer along with the 0-shaped groove by machining. Good, the thickness of the lower layer is 1μ
It has been experimentally confirmed that peeling due to machining hardly occurs when the thickness is about m.

Further, in this embodiment, the sendust thin film is formed by chemical etching, but it goes without saying that other well-known etching methods may be used, such as ion beam etching.

Furthermore, the same effect as in this embodiment can be obtained by using permalloy or an amorphous magnetic material other than sendust as the material of the thin film having a high saturation magnetic flux density.

In manufacturing the magnetic head according to the present invention, a thin film with a high saturation magnetic flux density can be simultaneously formed on the entire surface of the abutting portion of the ferrite wafer, and the 0-shaped groove can be processed with relatively rough precision. Higher productivity can be obtained compared to conventional manufacturing methods.

[Brief explanation of the drawing]

FIG. 1 is an enlarged partial plan view of a composite magnetic head according to the present invention, FIG. 2 is a perspective view of a pair of block halves, FIG. 3 is a perspective view of a magnetic head block, and FIG. 4 is a completed magnetic head. FIGS. 5(a), 5(b), and 5(c) are explanatory diagrams showing a method of forming a thin film by etching, and FIG. 6 is an enlarged partial plan view of a conventional composite magnetic head. (2)...Magnetic head half, (3)...Sendust thin film, (30)...Side surface, (4)...Nonmagnetic layer, (5)...Track width ruler IlI Groove, W...Track width. Figure 1

Claims (1)

[Claims] (1) A thin film of a magnetic material having a saturation magnetic flux density higher than that of the magnetic material is provided at the abutting portion of at least one of the magnetic head halves of a pair of magnetic head halves made of a high resistivity magnetic material; In a composite magnetic head in which a magnetic gap parallel to the abutting portion is formed between the thin film and the other magnetic head half, the thin film has a top surface facing the magnetic gap having a high flatness. The thin film is formed to have a width that exactly matches a predetermined track width W, and both side surfaces of the thin film extend downward from both ends of the upper surface while gradually increasing in width, and reach the bonding surface with the one magnetic head half. . A composite magnetic head, wherein the width of the thin film bonded to the bonding surface of the one magnetic head half is larger than the upper surface of the thin film.