JPS63231709A - Magnetic head - Google Patents

Abstract

PURPOSE:To reduce eddy current loss and to prevent a dummy gap from being formed by forming ferromagnetic metallic thin films on the joined surfaces of magnetic core half bodies and making them abut on each other, and forming cracks in the thin films in a film thickness direction. CONSTITUTION:The fine cracks 17 (17a and 17b) perpendicular to gap formation surfaces 16 are formed in the ferromagnetic metallic thin films 13a and 13b with high saturation magnetic flux density which are arranged nearby the gap 12 of a couple of magnetic core half bodies 11a and 11b. Thin films 13 (13a and 13b) are vapor-deposited on planes forming the core half bodies first and then the planes become concave because of their coefficients of thermal expansion. Grooves are formed in those two planes, which are put opposite each other; and glass 15 is charged and the planes are pressed and heated to form the cracks 17. Those cracks decrease the electric resistance of the thin films 13 and then the eddy current loss is reduced, so that a high recording reproduction output is obtained in a high frequency range.

Description

Detailed Description of the Invention (a) Field of Industrial Application The present invention relates to a magnetic head. In particular, in order to cope with a metal tape having a high coercive force, a high saturation magnetic flux density is applied to the vicinity of the gap of the magnetic core. The present invention relates to a so-called composite magnetic head in which a ferromagnetic metal thin film is arranged.

Conventional technology In recent years, 8mm VTR (video tape recorder) and DAT
In magnetic recording and reproducing devices such as digital audio tape recorders (digital audio tape recorders), the recording signal density has been increasing, and metal tapes with high residual magnetic flux density and high coercive force are being used to accommodate this high density recording. It has become so. As a magnetic head compatible with this high coercive force metal tape, a so-called composite magnetic head was proposed in which the gap area is made of a ferromagnetic metal thin film (sendust, amorphous alloy, etc.) with a higher saturation magnetization than ferrite. has been done.

FIG. 7 is a plan view showing the tape sliding surface of this conventional magnetic head. As you can see from this figure, the ferrite core (1
) and the ferromagnetic metal thin film (2) (3) is not parallel to the gap forming surface (4). This is to prevent the joint surface (3) from operating as a pseudo gap.

However, recently, a 7-elite core (as shown in Fig. 8), which is easier to manufacture than the magnetic head shown in Fig. 7, has been developed.
5) and the ferromagnetic metal thin film (6) is parallel to the gap forming surface (8). By reducing the pressure during welding, the joint (
7) A magnetic head has been proposed in which the magnetic head is prevented from operating as a pseudo gap.

-Increasing eddy current loss is an important problem in magnetic heads such as those described above. In the case of a slope type magnetic head, Japanese Patent Laid-Open No. 60-32107 (C) 11 B5
/127), the ferromagnetic metal thin film (
9) is laminated with a high hardness insulating film f111 such as 8102 interposed therebetween to prevent an increase in eddy current loss.

However, in the case of a parallel type magnetic head as shown in FIG. 8, even if ferromagnetic metal thin films are laminated with a high-hardness insulating film interposed therebetween in the same manner as described above, there is a difference between the surface on which the ferromagnetic metal thin films are deposited and the gap formation. Since the planes are parallel, the direction in which the magnetic flux passes is approximately perpendicular to the lamination plane.

It was not possible to reduce eddy current loss. Moreover, there is a possibility that the high hardness insulating film may act as a pseudo gap.

(c) Problems to be solved by the invention The present invention has been made in view of the drawbacks of the above-mentioned conventional examples.
The object of the present invention is to provide a magnetic head that can reduce eddy current loss and prevent the generation of pseudo gaps in both slope type and parallel type composite magnetic to rad systems.

2) Means for solving the problem A ferromagnetic metal thin film is formed on the joint surface of a pair of magnetic core halves made of ferromagnetic oxide, and the ferromagnetic metal thin films are brought into contact to form a magnetic gap. In the composite magnetic head, cracks are formed in the ferromagnetic metal thin film in the film thickness direction.

According to the above configuration, the ferromagnetic metal thin film increases the stain resistance at the cracks and reduces the eddy current loss, and since the cracks are not parallel to the gap forming surface, they do not operate as a pseudo gap.

(F) Embodiment An embodiment of the present invention will be described in detail below with reference to one drawing.

FIG. 1 is a perspective view showing the external appearance of the composite magnetic-RAD device of this embodiment, and the second factor is a plan view showing its tape sliding surface.

This magnetic head has a pair of magnetic core halves (11a) (111) made of ferromagnetic oxide such as Mn-Zn7 elite.
A ferromagnetic metal thin film (13fL) (131) such as Sendust with a high saturation magnetic flux density is arranged near the magnetic gap σ2 of the magnetic core half body (11& ) (11b)
ts [151 is filled. The magnetic core half (1
11 (111)) and the ferromagnetic metal thin film (13a) (i
3b) (19PL) (191)) is parallel to the gap a'a forming surface (16!L) (161)). The ferromagnetic metal thin film (16IL) (131)) is attached to the magnetic gear (121 forming surface (16&) (16t+).
) are divided by cracks (17a) and (17b) with a width of a little less than 1 μm formed in a direction (film thickness direction) perpendicular to the film thickness direction.

Incidentally, the front g8 crack (17a) (17'') is generated when the ferromagnetic oxide substrate is bonded to glass.

Next, a method for manufacturing the magnetic head shown in FIG. 1 will be described, particularly the step of depositing a ferromagnetic metal thin film on a ferromagnetic oxide substrate and the step of glass bonding one ferromagnetic oxide substrate.

1) First, a ferromagnetic metal thin film (13a
). The sputtering conditions at this time were as follows:
Distance between targets is 74-, input power is 500W, Ar
The gas pressure is 3XiQ-10rr. When sputtering is finished under these conditions, the ferromagnetic metal thin film (13a), which has a larger coefficient of thermal expansion than the ferromagnetic oxide substrate (1), has tensile stress due to the temperature drop at that time. .

Therefore, as shown in the third factor, the substrate (2) has the thin film (
The upper surface (20a) on which 13a) is formed is curved to become a concave surface. Then, as shown in FIG. 4, a groove 1211 is processed on the upper surface (20&) of this ferromagnetic oxide substrate 2 to form a gap forming surface (16a).

Next, two substrates shown in FIG. 4 are prepared, and a first substrate (24&) is created by forming the groove (winding groove (c) perpendicular to 2D) on the upper surface (20a) of one of them. , the other top surface (2
01L) to form a winding groove [with] and a glass rod insertion groove (to) perpendicular to the groove (211) to form the second substrate (241).
Create. Then, as shown in FIG. The gap forming surfaces (16!L) (16k) of the second substrates (241L) (24b) are opposed to each other, and a glass rod is inserted into the glass rod insertion groove c2. And the first one above. While applying pressure F from both sides of the second substrate (243) (241)), the temperature was raised to 800°C over about 2 hours.
Leave it for 10 minutes to melt the glass rod (E) and dissolve the first glass rod (E).
．． The second substrates (24!') (24b) are glass-bonded. At this time, the ferromagnetic metal thin film (1381 (13'b
) has the gap forming surface (161!L) (161))
A crack (17 &) (17
11) occurs.

Thereafter, the composite magnetic head shown in FIG. 1 is formed by cutting and polishing using well-known techniques.

11) Therefore, the distance between the substrate and the target of the above-mentioned sputtering apparatus is set to 72. When a ferromagnetic metal thin film is deposited on a ferromagnetic oxide substrate by changing to . When the distance between the target and the substrate is shortened in this way, the sputtering energy increases, so the number of adhering particles from the target increases, and Ar gas or the like may also be mixed into the film, so that the film tends to spread. Since this spreading force is greater than the stress caused by the above-mentioned difference in thermal expansion coefficients, the ferromagnetic oxide substrate warps so that its upper surface becomes convex, as described above.

This convexly curved first. When the second substrate is glass-bonded by increasing the temperature while applying pressure from both sides, a crack is generated in the uIJ thin film perpendicular to the gap forming plane.

This is because even if there is a force that tries to spread the thin film at the time of forming the thin film, that force is small, so as the temperature rises during glass bonding, the thin film becomes denser and its volume shrinks. This is because Ar gas and the like mixed into the thin film during film formation are removed, and the surface on which the thin film is formed becomes a concave surface. However, this n is 1
) The number of the first cracks is smaller and the width of the fifth crack is smaller than that of the magnetic head manufactured by the above method.

As mentioned above, either 1) tensile stress is already generated in the thin film when forming the thin film, or 11) the tensile stress is spread to the extent that it occurs in the thin film due to the temperature rise during glass bonding. Cracks can be formed in a ferromagnetic metal thin film by generating this force during thin film formation.

FIG. 10 is a diagram showing the frequency characteristics of the reproduction output of the magnetic head of this embodiment in which the ferromagnetic metal thin film has a crack and the conventional magnetic head without a crack. As can be seen from this figure, cracks (17a) (
171)) of the present embodiment can obtain a higher reproduction output than the conventional magnetic head.

In the above magnetic head, one ferromagnetic metal thin film (131
') (131)) cracks (17a) (17b) increase the electrical resistance of the ferromagnetic metal thin film (131!L) (13b), resulting in eddy current loss and high frequency signal recording and reproduction output. improves. In addition, the crack (171L
) (171)) becomes larger than 1 μm, the cracks (176) (171)) have the first . When the second substrate is bonded, the glass is filled and the ferromagnetic metal thin film (13!L
) (131)) is reinforced, and the electrical isolation of the ferromagnetic metal thin films (16a) (13t)) becomes even more favorable, which is highly effective in reducing eddy current loss.

Furthermore, as shown in FIG. 6, even if the number of cracks (17!L) (171)) formed in the ferromagnetic metal thin films (13a) (131)) facing each other across the magnetic gap az is different, , obtain the same effect as above.

In the above case, the orientation of the substrate was adjusted by the distance between the substrate and the target, but it can also be adjusted by the pressure of Ar gas.

(G1. Effects of the Invention According to the present invention, it is possible to provide a magnetic head that can obtain high recording and reproduction output in a high frequency region by reducing eddy current loss.-

[Brief explanation of the drawing]

Figures 1 to 6 relate to the present invention; Figure 1 is a perspective view showing the external appearance of the magnetic head, Figure 2 is a plan view showing the tape sliding surface of the magnetic head, Figures 6 and 4. and the fifth factor are diagrams showing the method of manufacturing the magnetic head, respectively, and FIG. 6 is a plan view showing the tape sliding surface of the magnetic head of another embodiment. FIG. 7, FIG. 8, and FIG. 9 are plan views showing the tape sliding surface of a conventional magnetic head, respectively. FIG. 10 is a diagram showing the frequency characteristics of the magnetic head reproduction output. CIl &) (111))...Magnetic core half, (13.
...Magnetic gap, (13a) (131))...Ferromagnetic metal thin film, (16a) (16'b)...Gap forming surface. (17a) (171:+) ...Crack, (
lE9...Glass.

Claims (1)

[Claims] (1) In a composite magnetic head in which a ferromagnetic metal thin film is formed on the joint surfaces of a pair of magnetic core halves made of ferromagnetic oxide, and a magnetic gap is formed by abutting the ferromagnetic metal thin films against each other. , a magnetic head formed by forming cracks in the film thickness direction in the ferromagnetic metal thin film.