JPS63201905A - Composite type magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To record and reproduce a high frequency signal by using a glass material having a set point <=300 deg.C for a first bond generating a composite core and a second bond jointing the half body of the magnetic core. CONSTITUTION:The glass material same as that which have been used as the conventional second bond is used for the first bond 15 and 15' jointing 'Sendust(R)' sheets 12 and 12' and Ferrite magnetic materials 13 and 13', the second bond 19 which is to be melted and filled in joint grooves 18 and 18', and mold glass 23 which is to be melted and is filled in track width restriction grooves 22 and 22'. Namely, the softening point of the glass material is 350 deg.C, and the set point is 235 deg.C. With using such glass material, the occurrence of thermal stress by the difference of a thermal expansion coefficient between the 'Sendust(R)' material and the Ferrite magnetic material can be reduced. Consequently, the coercive force HC of the composite type magnetic head can be reduced, whereby a deletion operation can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic head for a magnetic recording/reproducing device, and more particularly to a structure of a magnetic head suitable for recording/reproducing high frequency signals and a method for manufacturing the same.

(Prior Art) Magnetic heads that are compatible with magnetic tapes (such as metal tapes) that generally have high coercive force require a high saturation magnetic flux density during recording, and in order to obtain sufficient playback sensitivity during playback, particularly It is necessary to have high magnetic permeability in the high frequency region. In addition, metallic magnetic materials such as Sendust (registered trademark) and amorphous alloy are used as magnetic head materials that can achieve high saturation magnetic flux density, and ferrite magnetic materials and other magnetic head materials that have high magnetic permeability in the high frequency region are used. Oxide-based magnetic materials are known.

However, magnetic heads made only of metallic magnetic materials can be said to have good characteristics during recording, but during reproduction, because the electrical resistance of the metallic magnetic material is small, magnetic permeability decreases due to eddy currents, especially when the operating frequency is high. Indeed, the decrease in the magnetic flux is remarkable, and the reproduction characteristics become poor. Similarly, a magnetic head made of only oxide-based magnetic material has good characteristics during reproduction, but is not sufficient during recording.

Therefore, in order to improve the characteristics during both recording and reproduction, various so-called composite magnetic heads have been devised that have a composite structure of a metal-based magnetic material and an oxide-based magnetic material.

FIG. 15 is a partially enlarged plan view of the core sliding surface of the conventional composite magnetic head 10, and FIG. 16 is a plan view showing the entire composite magnetic head 10 shown in FIG.

In FIGS. 15 and 16, 11.11' is a magnetic core half, and sendust sheets 12, 12' having a thickness equivalent to the track width are made of a ferrite magnetic material made of, for example, single crystal ferrite, 13.13 14 and 14' are formed on the end faces thereof.

15.15' is the first bonding agent for bonding the Sendust sheet 12.12' and the ferrite magnetic material 13.13', and a relatively high melting point glass material having a softening point of 450 to 550°C is used. There is. Both magnetic core halves 11.
A thin film 8102 (not shown) is formed on the tape sliding surface 16 side of the abutting surface 14 and 14' of 11' to form a magnetic gap 17 on the tape sliding surface 16. 18.18
' are joint grooves formed on the abutting surfaces 14 and 14', respectively, and the softening point of approximately 350 in the joint grooves 18 and 18'
A glass material having a relatively low melting point of around 100° C. is melted and filled as a second bonding agent. 20 is one abutment surface 14
A winding wire (not shown) is wound in this groove 20 using winding guides 21 and 21'. Further, a part of the winding groove 20 is filled with the same glass material as the second bonding agent 19. 22.22' is the winding groove 2 on the tape sliding part 1116 of the magnetic core half 11°11'.
A track width regulating groove formed to communicate with 0,
The grooves 22, 22' are formed in a half-moon shape with the magnetic gap 17 as the apex, and the bonding grooves 18, 18 are formed in these grooves 22, 22'.
A molded glass 23.23 made of the same material as the glass material 19 melted and filled inside the glass 19 is melted and filled.

(Problem to be Solved by the Invention) However, after recording a signal on a magnetic tape using the conventional composite magnetic head 10 configured as described above, when the tape is rewound for playback, the composite magnetic head 10 A phenomenon in which the recorded magnetization of the portion in contact with the head 10 deteriorates, that is, an erasing phenomenon occurred.

In order to elucidate the cause of this, the inventors conducted intensive research and found that the coercive force Ha of the composite magnetic head was Ha>Q, 35
It was found that it showed an abnormally high value of 0e (Oersted).

By the way, the coercive force Hc of sendust and single crystal ferrite before being processed into a magnetic head is l" (c-110,03
50e, which is about an order of magnitude lower. The reason for this is thought to be as follows.

FIG. 17 is a graph showing the thermal expansion coefficients of sendust material and ferrite material, and as is clear from the graph, the difference in the thermal expansion coefficients between the two becomes larger as the temperature increases.

Therefore, when bonding sendust material and ferrite material using glass or the like, the molten glass is cooled and becomes substantially solid at a temperature called "set point J", which is close to the strain point. If there is a difference Δ× in thermal expansion coefficient between sendust material and ferrite material, this difference ΔX
It is thought that an internal stress proportional to is generated in the magnetic core and increases the coercive force Hc, and as a result, the magnetic core becomes easily magnetized, and a part of the recording track is erased when the magnetic tape is rewound.

For example, the first bonding agent 15. for bonding the sendust sheet 12.12' and the ferrite magnetic material 13.13'.
Since the set point A of the bonded glass used as 15' is A-345°C, the difference Δx1 in the linear thermal expansion coefficient between the sendust material and the ferrite material is Δx1-0.6x.
10-3, and since the set point B of the glass used as the second bonding agent 18 for bonding the magnetic core halves 11 and 11' is B-235°C, the coefficient of linear thermal expansion at that time is The difference Δx2 is ΔX2-0.2X10''
As a result, when comparing Δx1 and Δx2, Δx
1 is 3 times Δx2, and the first adhesive is stronger than the second adhesive.
It is predicted that the occurrence of thermal stress will be greater when using adhesives such as

(Means for Solving the Problems) The present invention has been made to solve the above problems, and it integrates a sendust material having a thickness equivalent to the track width and a ferrite magnetic material using a first bonding agent. It consists of a pair of magnetic core halves that are joined to each other and have an abutting surface on the end surface.
A composite type formed by forming a magnetic gap thin film part and a joint part on at least one of the abutting surfaces, and joining these pair of magnetic core halves together by disposing a second bonding agent in the joint part. The present invention provides a composite magnetic head and a method for manufacturing the same, wherein the first bonding agent and the second bonding agent are made of a glass material having a set point of about 300° C. or less. be.

(Example) FIG. 1 is a partially enlarged plan view of the core sliding surface of the composite magnetic head 3° according to the present invention, and FIG. 2 shows the entire composite magnetic head 30 shown in FIG. 1. FIG.

The composite magnetic head 30 of the present invention will be explained below with reference to FIGS. 1 and 2.
Since the configuration is almost the same as that of the conventional composite magnetic head shown in the figure, the same components are given the same reference numerals, and the explanation will be omitted and only the configuration points that are different from the conventional example will be explained.

The composite magnetic head 30 of the present invention differs from the conventional composite magnetic head 10 in that the sendust sheets 12, 12'-
and a ferrite magnetic material 13 consisting of single crystal ferrite, etc.
．． 13', the first bonding agent 15, 15', the bonding agent 19, which is melted and filled into the bonding groove 18, 18', and the mold glass 23, which is filled with Wim into the track width regulating groove 22, 22'. The point is that a glass material similar to that used as the second bonding agent 19 in the conventional example is used. This glass material has a softening point of 350"C and a set point of 235"C.

By using the above glass material, the difference Δx1 in thermal expansion coefficient between the conventional ferrite material 13.13' and the sendust sheet 12°12' can be reduced from Δxi-mo, eX10-3 to Δx2-0.2X10''''3 In other words, it was possible to reduce the thermal stress to about 1/3, thereby making it possible to reduce the thermal stress to about 173, and suppressing the coercive force H0 of the composite magnetic head 30 to about 0.25. As a result, it was possible to obtain a magnetic head with good characteristics without the occurrence of demagnetization phenomenon in the composite magnetic head 30. According to the inventor's research results, the coercive force Hc of the magnetic head is 0.
．． 3, the demagnetization phenomenon of the magnetic head becomes so small that it does not pose a practical problem, and the difference in thermal expansion coefficient between ferrite magnetic material and sendust material that satisfies this condition is approximately 0.3X1.
Therefore, it was found that the set point of the glass used as a bonding agent should be 300°C or less.

Next, a method of manufacturing a composite magnetic head according to the present invention will be explained.

3 to 14 show a composite magnetic head 30 according to the present invention.
FIG. 2 is an explanatory diagram showing the main steps of the manufacturing method, and will be explained below using each diagram.

(1) As shown in FIG. 3, the sendust sheet 12 is polished to a predetermined track width t. After that, as shown in Figure 4, a non-magnetic film (AJ120a, S
i 02 ) 40 0.1 μl may be given with WI.

(2 As shown in FIG. 5, both sides 1 of the ferrite magnetic material 13
3a, 13b is polished, and as shown in FIG. 6, a first bonding agent 15 made of glass having a set point of 300° C. or less is applied to the polished surfaces 13a, 13b to a thickness of about 1 μm using a thin film deposition technique. Deposit it on the surface.

(3) As shown in FIG. 7, the sendust sheets 11 and the ferrite magnetic material 13 that have gone through the steps (1) and (2) are alternately laminated, then pressurized and heated to the working temperature to obtain the block 41.

(4) As shown in FIG. 8, a plurality of yocan-shaped blocks 42 are obtained by cutting the block 41 so as to have an azimuth angle of θ with respect to the stacking direction Y.

(5) As shown in FIG. 9, track width regulating grooves 22 are formed along both sides of the sendust sheet 12 on the abutting surface 14 of the yoke-shaped block 42.

(a) As shown in Fig. 10, the glass material 1 used in step (2)
Molten glass 23 is formed by melting and filling the same glass material as in No. 5.
form. At this time, pressure is applied in the direction of the arrow so that the distance between the sendust sheet 12 and the ferrite magnetic material 13 does not increase.

(7) As shown in FIG. 11, prepare a pair of yorcan-shaped blocks 42 and 42' obtained in step (6), and install a winding groove 20 in the abutting surface 14' of one yorcan-shaped block 42'. and a joining groove 18' is formed, and only the joining groove 18 is formed on the abutting surface 14 of the other yoke-shaped block 42,
Furthermore, a winding guide groove 2 is provided at the rear of the abutting surface 14, 14'.
1.21' respectively.

(8) As shown in FIG. 12, after mirror polishing the abutting surfaces 14°14', the thickness is 1/2 of the length of the magnetic gap 17, for example, 5i02°A! A gap material 43.43' such as 20s is formed at a predetermined portion of the abutting surface 14.14'. At this time, the glass thin film for adhesion 44.44'
Gap material 43.43 on a part of the butt surface 14゜14'
(The glass material for this glass thin 11144.44' may be made of the same material as the first bonding agent 15.)

■ As shown in FIG.
．． A glass rod made of the same material as the first bonding agent is inserted into 18', and the yocan-shaped blocks 42' and 42 are heated to a predetermined working temperature while being pressed in the direction of the arrow to obtain a composite block 45. . At this time, the pressing direction is not only in the direction of the arrow (in order to prevent the first bonding agent 15 formed by bonding the sendust sheet 12 and the ferrite magnetic material 13 from softening and peeling between them, Also pressurize.

(10) As shown in Figure 14, this composite block 4
5 as indicated by the chain line 46, the sendust sheet 12.1
2', a composite magnetic head main body 30 of the present invention shown in FIGS. 1 and 2 before tip polishing can be obtained.

(Effects of the Invention) As described above, in the composite magnetic head of the present invention, the first bonding step for forming a composite core by bonding a sendust sheet having a thickness equivalent to the track width and a ferrite magnetic material. Since a glass material having a set point of about 300°C or less is used as the second bonding agent for bonding a pair of magnetic core halves made of the compound core and the composite core to form a composite magnetic head, Sendust It is possible to reduce the occurrence of thermal stress due to the difference in thermal expansion coefficient between the magnetic material and the ferrite magnetic material, and as a result, the coercive force Ha of the composite magnetic head can be reduced, making it possible to eliminate the erasing effect. , it is possible to manufacture a composite magnetic head having good magnetic properties.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged plan view of a core sliding surface of a composite magnetic head 30 according to the present invention, FIG. 2 is a plan view showing the entire composite magnetic head 30 shown in FIG. 1, and FIG. - FIG. 14 is an explanatory diagram showing the main steps of the method for manufacturing a composite magnetic head 30 according to the present invention, and FIG. 15 is a diagram showing a conventional composite magnetic head 1.
16 is a partially enlarged plan view of the core sliding surface of No. 0, and FIG. 16 is a plan view showing the entire composite magnetic head 10 shown in FIG.
FIG. 7 is a graph showing the thermal expansion coefficients of sendust material and ferrite material. °11...Magnetic core half, 12.12'...Sendust sheet, 13...Ferrite magnetic material, 14...
Abutment surface, 15... First bonding agent, 16... Tape sliding surface, 17... Magnetic gap, 18... Bonding groove,
19... Second bonding agent, 20... Winding groove, 21.2
1'...Winding guide groove, 22...Track width regulating groove, 23...Mold glass, 30...Composite magnetic head body according to the present invention, 40...Nonmagnetic film, 41...・
・Block, 42... Yokan-shaped block, 43...
・Gap material, 44-... Glass for adhesion IN! , 45・
...Composite block. fI FEr 222'I 7 4 13:I 61 years old 7E
Age 81 years old 9th 7′io z l6r7 bu, 7Fi1”'(”)

Claims (2)

[Claims] (1) A sendust material and a ferrite magnetic material having a thickness equivalent to the track width are integrally bonded with a first bonding agent,
It consists of a pair of magnetic core halves with abutting surfaces formed on their end faces, a thin film part for a magnetic gap and a joint part are formed on at least one of the abutting faces, and a second magnetic core half is formed on the joint part of the pair of magnetic core halves. In the composite magnetic head which is integrally bonded by disposing a bonding agent, the first bonding agent and the second bonding agent are made of a glass material having a set point of about 300° C. or less. Features a composite magnetic head. (2) A step of attaching a non-magnetic thin film to both sides of the sendust material having a thickness equivalent to the track width. After polishing both sides of the ferrite magnetic material, a bonded glass material having a set point of about 300°C or less is applied to both sides. adhesion step, step of obtaining a block by alternately laminating the sendust material and ferrite material and joining them at a working density while applying pressure; cutting the block at an angle of azimuth angle θ with respect to the stacking direction; In the step of obtaining a shaped block, an abutting surface is formed on the cut surface of this yorcan-shaped block, and a track width regulating groove is formed on this abutting surface, and then a glass material having the same set point as the bonded glass material is bonded to the track width. A step of melting and filling into the regulating groove, a step of forming a predetermined joint groove and a winding on the abutting surfaces of the pair of yorcan-shaped blocks, and a step of forming a magnetic gap material on the abutting surfaces of the pair of yorcan-shaped blocks. butting, placing a glass material similar to the bonding glass material in the bonding groove and the winding groove, and heating it to a working temperature to obtain a composite block;
A method for manufacturing a composite magnetic head, comprising the step of cutting this composite block to obtain a magnetic core having predetermined dimensions.