JPS58220232A - Magnetic head and its production - Google Patents

Abstract

PURPOSE:To reduce the eddy current loss and at the same time to improve the recording/reproducing efficiency for a magnetic head, by using a magnetic material of high saturated magnetic flux density at the area near a front gap and a ferror magnetic material at the rest core area respectively. CONSTITUTION:Rectangular parallelepiped blocks 2 and 2' of nonmagnetic material are adhered to the edge parts of rectangular parallelepiped blocks 1 and 1' to obtain rectangular parallelepiped blocks 3 and 3'. A magnetic material of high saturated magnetic flux density, e.g., a metallic magnetic material such as ''Permalloy'', etc. are used to form thin films 6 and 6' of 10-20mum on the entire side surface of the gap butted face between blocks 3 and 3'. Then recess parts 7 and 7' are formed orthogonally to the longer side direction of the blocks 3 and 3'. A nonmagnetic thin film 8 having a high softening point is formed at the front gap part on the film 8 having a high softening point is formed at the front gap part on the film 6'; while a glass thin film 9 of a low softening point is formed at the rear gap part of the film 6' respectively. Then blocks 3 and 3' are joined together, and glass is filled into the parts 7 and 7' as well as cut parts 4 and 4'. Thus a composite block 12 is formed. The block 12 is cut with a prescribed inclination theta to obtain a magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head and a method for manufacturing the same, in which, for example, a magnetic material with a high saturation magnetic flux density such as Sendust alloy is used in a portion near the front gap, and a ferromagnetic material such as ferrite is used in the remaining core portion. By constructing a magnetic head using the magnetic recording medium, and by constructing the magnetic recording medium sliding contact surface of the magnetic head from a non-magnetic material except for the portion near the front gap, eddy current loss is reduced and recording and reproducing performance is reduced. An object of the present invention is to provide a high-performance magnetic head with excellent efficiency and a method for manufacturing the same.

For example, in order to improve the performance and miniaturize video tape recorders, it is necessary to use magnetic tape with high coercive force. Since magnetization is difficult, a strong signal magnetic field must be applied from a magnetic head to sufficiently magnetize this type of high coercive force magnetic tape.

However, in order to apply a strong signal magnetic field, even if a large signal current is passed through the windings of the magnetic head to increase the magnetomotive force, the magnetic herad core that constitutes the magnetic path inside the magnetic head will not come into contact with the recording medium. The part becomes magnetically saturated and 1-displaces,
It may not be possible to extract a sufficiently strong signal magnetic field. That is, it is desired that there is a relationship such as Bs≧6Hc between the coercive force Hc of the magnetic recording medium and the saturation magnetic flux density Bs of the magnetic material of the magnetic head, for example, 1000-1800.
The magnetic head used for Oersted's high coercive force magnetic recording media has a core saturation magnetic flux density of approximately 6000.
~11000 Gauss is said to be necessary.

Therefore, if a metal alloy magnetic material with a high saturation magnetic flux density is used as the magnetic material of the magnetic head instead of an oxide-based magnetic material such as Mn-Zn ferrite, for example, the Bs of the metal magnetic material becomes Mn- Since it has about twice the amount of Znn ferrite BS, it can be used satisfactorily for magnetic recording media with Hc up to about 1600 oersteds, and magnetic rad using metal alloy magnetic materials is being developed. . However, metal alloy magnetic materials have the disadvantages of ■low specific resistance, ■low magnetic permeability in the video band, and ■poor wear resistance, and are also difficult to process compared to Mn-Zn ferrite, etc. There are also some drawbacks.

However, the saturation of the magnetic head mentioned above becomes a problem because
Since only the part of the magnetic bed core is near the front gap, the part of the magnetic bed core near the front gap is made of a metal magnetic material with a large saturation magnetic flux density, and the other parts are made of a metal magnetic material with a large permeability in a high frequency region. By using the obtained 7-elite, the above-mentioned drawbacks can be minimized. For example, in a magnetic head that performs high-density recording and reproduction using a magnetic recording medium with high coercive force, most of the core that makes up the magnetic head is made of ferrite that has a low saturation magnetic flux density but a high effective magnetic permeability. Attempts have been made to form only the portion near the front gap where saturation is a problem with a metal alloy magnetic film having a high saturation magnetic flux density. However, it is difficult to form a metal alloy magnetic film only in the vicinity of the front gear.In other words, in order to create a magnetic head with such a configuration, ferrite must be applied to the thickness of the metal alloy magnetic film. Either the front gap must be etched in advance or the thickness of the front gap must be made thinner than the rear gap by the thickness of the metal alloy magnetic film. Therefore, the former method requires an etching process and reduces productivity. In the latter method, the bonding surface of the gap between the core halves becomes uneven during gap formation, resulting in poor gap width accuracy, weak bonding strength, and low manufacturing yield. Furthermore, if the magnetic circuit is not composed only of the metal alloy magnetic material, that is, if the metal alloy magnetic film is formed only in the vicinity of the front gap, the magnetic properties of this material will not be fully utilized. However, it also has the disadvantage that it is unsatisfactory in the case of a magnetic recording medium with a larger He content.

Therefore, the present applicant has developed a magnetic head that eliminates the above drawbacks.
In other words, they proposed a magnetic head in which the magnetic material in the vicinity of the front and rear gaps of the magnetic head is made of a material with a saturation magnetic flux density higher than that of most other magnetic materials (Japanese Patent Application No. 57-63902). However, the magnetic head according to this proposal still has some problems. For example, in this proposed magnetic head, a minute gap is created between the ferrite core surface and the Sendust alloy film, and this acts as a pseudo gap on both sides of the regular magnetic gap.
This deteriorates the recording and reproducing characteristics.

The present invention eliminates the above-mentioned drawbacks, and examples thereof will be described below.

First, as shown in FIG. 1 a + b, the ends of rectangular parallelepiped blocks 1 and 1' made of a ferromagnetic material with good workability and high magnetic permeability, such as Mn-Zn ferrite, have a coefficient of thermal expansion equal to that of the ferromagnetic material. Rectangular parallelepiped blocks 2 and 2' made of a non-magnetic material such as ceramic and crystallized glass, which are approximately the same as those of the same material and have excellent wear resistance, are integrated with adhesive to form rectangular parallelepiped blocks 3 and 3.
′ constitutes.

Also, the rectangular parallelepiped blocks 1, 1' and the rectangular parallelepiped blocks 2, 2'
Step-shaped notches 4, 4' are formed at the opposite end, and a groove 5 serving as a winding window is formed along the longitudinal direction of at least one rectangular parallelepiped block 3'.

Next, as shown in FIGS. 2a and 2b, the entire surface of the gap abutting surfaces of the rectangular parallelepiped blocks 3 and 3' shown in FIG. A thin film 6 of a magnetic material with a high saturation magnetic flux density, such as a metal magnetic material such as sendust alloy or permalloy.
．． 6' is formed to a thickness of about 10 to 20 μm by sputtering or the like.

Next, as shown in FIGS. 3a and 3b, dicing is performed on the surfaces on which the thin films 6, 6' are formed, perpendicular to the longitudinal direction of the rectangular parallelepiped blocks 3, 3' on which the thin films 6, 6' are formed. A plurality of recesses 7, 7' are formed using a saw or the like.

Thereafter, as shown in FIG. 4, a non-magnetic thin film 8 made of, for example, quartz glass having a relatively high softening point is applied to the front gap portion on the thin film 6' surface of the rectangular parallelepiped block 3' shown in FIG. The gap width g of the magnetic head is formed by means such as sputtering, and a non-magnetic material having a relatively low softening point and approximately the same coefficient of thermal expansion as the thin film 6', such as a glass thin film 9, is formed in the rear gap portion. It is formed to be slightly thinner than g by means such as sputtering.

Then, the blocks shown in FIG. 3a and FIG. 4 above are
Match and butt the four parts 7 and 7', and cut out the notches 4, 4.
A glass rod 10.11 having a relatively low softening point, for example, about 400 to 500°C, is arranged in the groove and groove 5 formed by ', and the temperature near the working point of this glass rod, for example, about 700°C
By heating and press-bonding the rectangular parallelepiped blocks 3 and 3'
and the recessed portions 7, 7' and the notched portions 4, 4.
The portion ' is filled with glass to form a magnetic head composite block 12 as shown in FIG.

After that, the magnetic head composite block 12 shown in FIG.
In the figure, the virtual plane indicated by the dashed line, that is, the recesses 7, 7
′ and has a predetermined inclination θ to the abutting surfaces of the rectangular parallelepiped blocks 3 and 3′, as shown in FIGS. 7 and 8 (cross-sectional view taken along line A-A in FIG. 7). A magnetic head 13 is configured. 1 in Figures 7 and 8.
4 is a winding window, 15 is a front gap, 16.16' is a core made of a magnetic material with high saturation magnetic flux density, 17.17' is a core made of a ferromagnetic material, and 18.18' is a nonmagnetic This is the tape sliding contact surface made of material.

In the magnetic head constructed as described above, the majority of the core is made of a magnetic material with good workability and high magnetic permeability, and furthermore, the abutting surface of the half half of the core has a coefficient of thermal expansion substantially equal to that of the magnetic material, and A magnetic film with a higher saturation magnetic flux density than the magnetic material is formed so that the magnetic circuit of the magnetic head can be constructed only with this magnetic film, so the magnetic properties of this magnetic film effectively affect the characteristics of the magnetic head. The recording magnetic field strength becomes sufficiently strong. Further, since a magnetic film with a high saturation magnetic flux density is provided not only on the front gap portion but also on the rear gap portion side, a stable and highly accurate gap can be easily constructed, and the magnetic head can be manufactured at a high manufacturing yield.

Furthermore, in the magnetic head of the present invention, the magnetic tape sliding contact surface is made of non-magnetic material except for the magnetic material portion with high saturation magnetic flux density near the front gap.
The problem of pseudo gaps caused by the junction between the ferromagnetic material and the magnetic material with high saturation magnetic flux density does not occur, and stable recording and reproducing characteristics can be obtained.

As described above, in the magnetic head according to the present invention, at least the core portion near the front gap is made of a magnetic material 9 with a high saturation magnetic flux density, and the portion in contact with the magnetic recording medium is made of a magnetic material with a high saturation magnetic flux density near the front gap. Since the other parts are made of non-magnetic material, and most of the parts other than the area near the front gap and the part in contact with the magnetic recording medium are made of ferromagnetic material, it can be used for magnetic recording media with high coercive force.
In addition, the magnetic head does not have the problem of pseudo-gaps and has stable, high-performance recording and reproducing characteristics.Furthermore, the magnetic head manufacturing method according to the present invention involves joining a non-magnetic material block to the end of a ferromagnetic material block. A groove serving as a winding window is provided at a predetermined position of at least one of the two substantially rectangular parallelepiped blocks, and a plurality of four sections are formed at predetermined intervals in a direction substantially perpendicular to the groove. Two substantially rectangular parallelepiped blocks are formed, a magnetic film with a high saturation magnetic flux density is formed on the abutting surfaces of the substantially rectangular parallelepiped blocks, and a gap spacer is further formed on this magnetic film surface, and then the two substantially rectangular parallelepiped blocks are butted together. Since the composite block is bonded together and then cut into a predetermined shape along a predetermined imaginary plane, a magnetic head that can be applied to high coercive force magnetic recording media can be manufactured easily and with high manufacturing yield. The magnetic head manufactured by the above method has features such as being free from the problem of pseudo gaps.

[Brief explanation of the drawing]

Figure 1 a r b e Figure 2 a r b > Figure 3 a+
b and FIGS. 4 to 6 are explanatory diagrams of the manufacturing process of the magnetic head according to the present invention, and FIGS. 7 and 8 are explanatory diagrams of the magnetic head according to the present invention. 1.1'...cuboid block of ferromagnetic material, 2,2'...
・Rectangular parallelepiped block of non-magnetic material, 5...Groove, 6.6'
... Thin film of metal magnetic material, 7.7'... Concavity, 8...
・Nonmagnetic thin film, 12...Magnetic head composite block, 1
3...Magnetic head, 15...Front gap. (11) Figure 1 Figure 72 Figure 14

Claims (1)

[Claims] ■ At least the core portion near the front gap is made of a magnetic material with high saturation magnetic flux density, and the portion of the portion in contact with the magnetic recording medium other than the magnetic material with high saturation magnetic flux density near the front gap is made of non-magnetic material. A magnetic head comprising a ferromagnetic material, and further comprising a ferromagnetic material for most of the area other than the vicinity of the front gap and the portion in contact with the magnetic recording medium. ■ A groove serving as a winding window is formed in a predetermined position of at least one of the two substantially rectangular parallelepiped blocks formed by joining a non-magnetic material block to the end of a ferromagnetic material block;
In addition, a plurality of four parts are formed into two approximately rectangular parallelepiped blocks at predetermined intervals in a direction approximately perpendicular to the groove, and a magnetic film with a high saturation magnetic flux density is further applied to the abutting surfaces of the approximately rectangular parallelepiped blocks. After forming a gap spacer on the surface, two approximately rectangular parallelepiped blocks are butted and joined,
A magnetic head manufacturing method characterized in that the composite block is then cut along a predetermined virtual plane to form a predetermined shape.