JPS6398805A - Magnetic head - Google Patents

Abstract

PURPOSE:To improve the characteristic and to reduce the cost by forming the film thickness of the magnetic film so that the film thickness of the magnetic thin film varies in response to the depth with the range of the depth of the operating gap in core halves formed by coating an alloy magnetic film onto a high permeability material. CONSTITUTION:The relation of T=Wcostheta+Dsintheta exists where T is the thickness of an alloy magnetic film 2 coated on a slope S1 of a winding slot in the high permeability core halves 1, theta is an angle between the film 2 and a gap face 3, D is a gap in case of a slide face SIGMA1 passing just through point P, and W is a width on the face SIGMA1 of the film 2. In forming the heads in such a way that the boundary face between the core 1 and the film 2 has a prescribed slope to the gap face 3 and the film thickness T is varied in response to the gap depth D at a prescribed rate continuously, the contour effect is suppressed. Thus, the characteristic is improved and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a magnetic head, and in particular, to a magnetic head having a high permeability magnetic material.
This invention relates to a magnetic head coated with a high saturation magnetic flux density magnetic film.

[Conventional technology]

In recent years, MIG (Me
tal in gap) head has come to be used.

The MIG head has a Ti structure in which most of the core is made of a high magnetic permeability material such as ferrite, and the tip of the magnetic pole near the gap is made of a high saturation magnetic flux density material, that is, an alloy magnetic material such as permalloy, sendust, or amorphous. ing.

The simplest form of the MIG head near the electromagnetic transducer is shown in FIGS. 4(A) and 4(B). In the figure, 1 is a chip made of a high magnetic permeability material such as single crystal ferrite, 2 is a magnetic alloy film made of a high color summation magnetic flux density alloy such as Sendust, and 3 is a magnetic gap portion made of a nonmagnetic material. 4(A) shows a type in which no magnetic alloy film is deposited within the winding groove, and FIG. 4(B) shows a type in which no magnetic alloy film is deposited within the winding groove.

The basic structure of the MIG head is shown in Figure 4 (A).

In the crosspiece shown in (B), there is a type in which the boundary between the magnetic alloy film 2 and the high magnetic permeability material 1 on the sliding surface of the magnetic recording medium is parallel to the magnetic gap 3 (hereinafter referred to as P type), and a type in which the boundary between the magnetic alloy film 2 and the high magnetic permeability material 1 is parallel to the magnetic gap 3. A type (hereinafter referred to as A type) that is non-parallel and has an azimuth angle is considered. For example, P type MIG
The head is disclosed in Japanese Patent Application Laid-Open No. 51-140708, and the A type MIG head is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-32107.

However, in P-type MIG heads, a phenomenon called the contour effect occurs due to the discontinuity of magnetic properties at the boundary between the high permeability material and the alloy magnetic material, which is parallel to the magnetic gap. As shown in FIG. 5, ripples of about 3 to 4 dB appear in the frequency vs. output characteristic curve in some cases, so that this head has not yet been put to practical use as a recording/reproducing head.

The A-type MIG head was devised to avoid such a phenomenon, and the one disclosed in the above-mentioned Japanese Patent Laid-Open No. 60-32107 has been put into practical use for VTRs.

[Problem that the invention seeks to solve]

However, since the A-type MIG head generally has a more complicated structure than the P-type MIG head, the number of manufacturing steps is increased and the product yield is also lower. Therefore, the manufacturing cost was quite high.

In addition, when attempting to manufacture an A-type MIG head with a track width as wide as 60 μm, depending on the structure and manufacturing method, a magnetic alloy film with a thickness of around 40 μm may be deposited using a physical vapor deposition method such as sputtering. A process is required.

To form a film of such thickness by sputtering,
It takes several hours just to form the film, and even if the film is formed, the film itself or the ferrite substrate may crack or break due to the accumulation of internal stress. Therefore, machining and 500℃~
Few heads are completed through a harsh process such as a glass lava process at around 60°C, which results in a further decline in yield.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a magnetic head that can be manufactured using a simple manufacturing process, does not increase manufacturing costs, and has good electromagnetic conversion characteristics.

[Means for solving problems]

For this purpose, in the magnetic head of the present invention, core halves each having a high saturation magnetic flux density magnetic film coated on a high magnetic permeability magnetic material are butted together via a magnetic gap material. and the thickness of the magnetic film in at least one core half changes continuously at a substantially constant rate within the depth range of the working gap depending on the depth from the medium sliding surface of the magnetic head. It is structured as follows.

[Effect]

By configuring as described above, it is possible to reduce the influence of the electromagnetic conversion characteristics due to the contour effect, and since the film thickness of the magnetic film is continuously changed at a roughly constant rate, it is possible to The shape is simple, which is extremely advantageous in terms of manufacturing process.

(Example) The structure of the most typical example of the present invention is shown in Figures 1 (A), (B), and (C), and the manufacturing process is shown in Figure 2 (
This will be explained using A), (B), (C), and (D).

FIG. 1(A) is an external perspective view of the magnetic head of this embodiment, in which 1 is a ferrite block, 2 is a magnetic alloy film, and 3 is a ferrite block.
1 is a magnetic gap portion, 6 and 8 are low-melting glasses, and 9 is a wire-wound window. FIG. 1C shows details of the vicinity of the electromagnetic transducer section of the magnetic head shown in FIG. 1A. Figure 1 (C) is the same as Figure 1 (A).
) is a cross-sectional view of the magnetic head taken along the sliding direction of the medium.

':(', As shown in Figure 1 (C), the magnetic head of this embodiment has lj) Even though the basic configuration as seen from the moving surface side is the P type, it is made of high permeability wick material and high saturation 11i1. The boundary surface of the flux density material has an inclination in a certain direction, preferably an acute angle of 30° to 60°, with respect to the gap surface at least within the depth of the required day gap, and the film thickness changes continuously. I made it an addendum.

It has been found that by employing such a simple configuration, the ripple due to the contour effect can be suppressed to 1 dB or less, the head has sufficient electrical Iin conversion characteristics as a video head, and costs can be reduced.

The method for manufacturing the magnetic head of this embodiment will be described below with reference to FIGS. 2(A) to 2(E).

In Fig. 2 (A), 1 indicates a part of a direct cubic block of ferrite crystal, and its - face has three wall surfaces S.
l+2. A groove 4 for the winding window formed by S3 is cut, and the wall surface of the groove is also cut on the surface in which the groove 4 is carved, and sendust is formed.

11 Film 2 for alloys with high saturation magnetic flux density such as amorphous and permalloy? There are 11 people wearing leather. These alloy magnetic films are formed by a vapor deposition process such as sputtering, vapor deposition, physical vapor deposition such as plasma CVD, or chemical vapor deposition such as plating.

For example, when forming these films by sputtering, the three wall surfaces Sl of the winding window groove carved in the ferrite 1
, s2. In order to deposit a thicker film on the slope S near the sliding surface in step S3, it is desirable to perform the deposition from diagonally downward in the figure as shown by the arrow. If a gap depth of about 25 μm is required, such as in an 8 mm VTR, this slope S1 should be
It is sufficient to form the alloy stone RI film to a thickness of approximately 20 μm to 25 μm.

After film formation, as shown in FIG. 2(B), a metal rod 5 such as aluminum is dropped into the groove for the winding window, and the aluminum rods 55 are
After filling the groove with the first low melting point glass 6 having a melting point of around 0° C., polishing and lapping are performed to form abutting surfaces.

Next, as shown in FIG. 2(C), a large number of parallel grooves 7.
,7. ．． Machining the track width by cutting... Figure 2 (
C) shows the state in the middle of groove machining. Groove 71 +
2 After carving +..., if necessary, lightly wrap the mating surfaces to remove any stiffness caused by groove machining, and then apply non-magnetic gap material such as S+ 02 or CrO2 according to the designation. For example, sputtering is performed to a thickness of about 0.2 μm to complete the block processing before butting. Regarding the block without the winding window groove corresponding to the other half of the core, an alloy magnetic material of 10% was applied to the surface corresponding to the butting surface.
The film is formed to a thickness of 1 μm or more, preferably 20 μm, and a groove for track width processing is cut in advance.

These two blocks are butted together, and a second low melting point glass 81 having a melting point of 500°C to 550°C, which is the same as or slightly lower than that of the first low melting point glass 6, is prepared by using the track width groove etc. The block obtained by welding is shown in FIG. 2(D).

In FIG. 2(D), C13 is a magnetic gap, 8, . 82
．． ... is the second low melting point glass.

This block is cut out at the position indicated by the chain line to obtain a head depth. Regarding this head chip, a cross section passing through the center of the gap 3 and perpendicular to the gap plane, that is, the center line (D) in FIG. FIG. 2(E) shows the configuration of the cross section indicated by the dashed dotted line). In FIG. 2(E), the surface S of the groove for the winding window of the ferrite core 1 and the surface S facing the abutting surface. Point P indicates the line of intersection with

The head of this embodiment is machined so that the position of the sliding surface Σ in the initial state is at the same level as the point P or below the point P, as shown by the chain line. An enlarged view of point P in FIG. 2(E) and the vicinity of the gap is shown in FIG. 1(C).

As mentioned briefly above, in Fig. 1 (C), the sliding surface of the half-open core with the winding window is located at the intersection point P of the slope S1 of the winding window groove and the plane S0 parallel to the gap surface. Located above;
If a plane parallel to the gap plane remains within the gap depth range, a contour effect will appear, and if it is located at the same level as or below the plane Σ1 passing through point P, the contour effect will be suppressed. Side S
If 0 remains, the magnetic flux in the ferrite is on the surface S. It is presumed that the boundary surface So parallel to the gap between the two different materials acts like a pseudo-gap.

In FIG. 1(C), it is assumed that the thickness of the alloy magnetic film 2 deposited on the surface Sl is T, the angle between [2 and the gap surface is θ, and the sliding surface Σ passes through the apex point P. The distance from the surface Σ to the end point O in the gap depth direction, that is, the gap depth, is D,
When W is the distance from the gap to point P, that is, the width τ of the alloy magnetic film appearing on the sliding surface, W, D, θ
and T, T = W cos θ + D sin θ −−−−−−
The relationship (1) holds true. When targeting a head for recording and reproducing video signals, the gap depth D is 25 μm.
and the angle between the slope S1 and the gap surface is θ=45°,
For each case of θ = 60°, the width of the film surface C on the sliding surface is roughly changed to W = 0.5.10 μm, and the required film thickness T on the slope S1 is (1 ) is calculated from the formula,
The result will be as shown in Figure 1 (B).

As a result of making prototype heads of various shapes, it was found that the sharpness of the cutting edge increases as the film thickness T increases, and that the contour effect decreases as the film width W increases. was almost 1 dB or less. It should be noted that if the film thickness T is thick, the internal stress will increase accordingly, which will cause cracks and film peeling in various parts of the head during processing, reducing the yield, so it is desirable that the film thickness be thinner. Therefore, from FIG. 1(B), when W=10 μm or less, θ=45° is preferable. Note that in the case of a head with a large head width, a depth D of 10 μm is sufficient, so even if W=10 μm, the film thickness may be about 15 μm.

In reality, it is difficult to machine the sliding surface so that it passes through the intersection line (point P) of surfaces S0 and S1 at the top, and it is difficult to process the sliding surface by several microns in the direction of the gap depth.
There will be an error of m. At this time, the initial sliding surface is Σ, lower than
There is no problem if the gap depth D shifts in the direction of decreasing. On the other hand, when the sliding surface is located at an upward deviation of 8 degrees Σ2, if the deviation amount δ is 2 to 3 μm or less, that is, the surface S0
It has been found that if the remaining depth is 2 to 3 .mu.m or less, the ripple due to the contour effect will be 2 dB or less and will not have an adverse effect on the recording and reproduction of video signals. Therefore, in practice, the surface S0 is several μ in the gap depth direction.
A residual machining error of m should be allowed.

A perspective view of the external appearance of the head chip obtained according to the steps described in detail above is shown in FIG. 1(A).

When the head chip is immersed in an alkaline solution after the sliding surface has been processed, the aluminum rod is melted and the winding window 9 is formed.

Next, the vicinity of the electromagnetic transducer section of a magnetic head as another embodiment of the present invention is shown in FIGS. 3(A) to 3(F).

The head of FIG. 3(A) is produced by, for example, using the ferrite block of FIG. 2(B) by further polishing and lapping the alloy film of thickness t remaining on the abutting surfaces to expose the underlying ferrite surface. Figure 2 (D
) are butt-welded together, and the same steps as in the optical example are performed.

In this case, in FIG. 1(C), the interface S1 between the alloy magnetic film and the ferrite is a single plane that extends obliquely upward and intersects the gap plane at point R, and the alloy magnetic film appears on the sliding surface Σ1. The difference between the width PQ=W and θ, D, and T is as mentioned above (
A relational expression similar to expression 1) holds true.

The head in Figure 3 (B) uses the same one as in Figure 3 (A) for the core half hole with the winding window, and the core half hole to be matched does not have an alloy magnetic film on the lower core side. is used. Also, the structure is such that no gap material is adhered to the lower part of the core. In a magnetic head having such a 41°4 structure, the alloy fill films are arranged so that the tops thereof face each other on the joining surfaces and continuously surround the winding window, so that the magnetic resistance is minimized. has been done.

The head in FIG. 3(C) has three walls Sl of the winding window groove.
, S2. Slope SL intersects with the gap plane at an acute angle in S3
An alloy magnetic film is formed only on the surface. Further, as in other embodiments, the film thickness on the slope Sl may become thinner in the depth direction of the groove, as long as the necessary film thickness can be secured in the vicinity of the gap. The smaller the area and thickness of the alloy magnetic film deposited on the ferrite, the smaller the internal stress and the higher the processing yield.

In the head shown in FIG. 3(D), before cutting the winding window groove in the ferrite block, a groove having a slope Sl' is cut parallel to the groove, and an alloy magnetic film is formed on the surface of the groove. After that, a groove for the winding window is carved.

In this head, the boundary area between the two types of magnetic materials is further reduced, and the processing yield is improved.

The head shown in FIG. 3(E) is obtained by bending a single slope of the winding groove in the middle and forming an alloy magnetic film on the surface thereof. In this case as well, within the gap depth, alloy 6
The surface to which the n-type film is adhered is a single plane.

The head shown in FIG. 3(F) is obtained by forming winding window grooves on both of the two core halves that are brought into contact with each other, and forming an alloy magnetic film on the deformed slope S,''.

The purpose of this head deflection is to shorten the overall magnetic path length and improve the electromagnetic conversion efficiency of the head. Although the boundary surface 31'' between the alloy magnetic film 2 and the ferrite 1 is a curved surface, the angles formed between the tangential plane and the gap surface at each position on the curved surface within the gap depth range are all acute angles. Further, the curvature of the curved surface may have a sign opposite to that shown in the figure.

The above has shown various deformations of the structure within the cross section passing through the gap center of the head and parallel to the track direction. Core destination obtained by 11.1
Many combinations and modifications can be obtained, such as forming an alloy film on the side surface of the part.

In addition, even in a magnetic head in which the head is manufactured without going through the so-called butting process, a film of alloy magnetic film is similarly applied within the depth of the working gap in the core half on the side with the winding window. A similar effect can be obtained by changing the thickness at a substantially constant rate.

In the magnetic head of each embodiment of the present invention as described above,
The structure is such that the thickness of the magnetic alloy film in at least one core half changes at a roughly constant rate within the range of the depth of the working gap depending on the depth from the medium sliding surface of the magnetic head. Since the surface to which the magnetic alloy film is applied is almost a flat surface within the working gap depth range, processing is easy and deterioration of electromagnetic conversion characteristics due to the contour effect can be suppressed.

In addition, as a preferred embodiment of the present invention, as in each embodiment, the distance between the surface to which the magnetic alloy film is adhered and the magnetic gap becomes smaller as it approaches the medium sliding surface, that is, as it approaches the medium sliding surface. Accordingly, by configuring the magnetic alloy film so that the film thickness is reduced, the flow of magnetic flux becomes smoother, and the negative influence on the electromagnetic conversion characteristics caused by the contour effect can be suppressed more efficiently.

Furthermore, FIG. 1(A), FIG. 3(A), and (B).

The manufacturing process can be further simplified by using the slope of the winding groove as it is in the groove shown in <C> as the surface to which the magnetic alloy film is adhered.

By creating a structure in which the thickness of the magnetic alloy film does not change in the direction parallel to the magnetic gap, the track width can be selected independently of the thickness of the alloy film, which has the effect of allowing heads with wide track widths to be supplied at low cost. be.

(Effects of the Invention) As described above, according to the present invention, a magnetic head can be obtained which has a structure that is advantageous in terms of the manufacturing process and which exhibits little deterioration in electromagnetic conversion characteristics.

[Brief explanation of the drawing]

Figures 1 (A), (B), and (C) are diagrams for explaining the structure of a 6n air head as an embodiment of the present invention; Figures 2 (A), (B), and (C); (D). (E) is a diagram for explaining the manufacturing process of the magnetic head shown in FIG. 1, and FIGS. 3 (A) to (F) are diagrams for explaining the manufacturing process of the magnetic head shown in FIG. 1, respectively. 4(A) and 4(B) are diagrams showing the main structure of a conventional MIG head, and FIG. 5 is a diagram showing electromagnetic conversion characteristics of the head shown in FIG. 4. In the figure, 1 is a high magnetic permeability magnetic material block, 2 is a high saturation magnetic flux density magnetic alloy film, 3 is a magnetic gap, and 9 is 1S, a spring window.

Claims (3)

[Claims] (1) A magnetic head in which core halves each having a high saturation magnetic flux density film coated on a high magnetic permeability magnetic material are butted together via a magnetic gap material, wherein the magnetic film in at least one of the core halves is 2. A magnetic head, wherein the film thickness of the magnetic head changes continuously at a substantially constant rate within the depth range of an operating gap, depending on the depth from a surface of the magnetic head in sliding contact with a medium. (2) The thickness of the magnetic film in the portion where the film thickness changes does not change in the direction parallel to the magnetic gap at the surface where the medium slides. magnetic head. (3) In the one core half, the surface to which the magnetic film is applied in the part where the film thickness changes is a part of the bottom surface of the winding groove formed in the high permeability magnetic material. A magnetic head according to claim (1).