JPH0554323A - Production of composite magnetic head - Google Patents

Abstract

PURPOSE:To obtain the magnetic head eliminating the stress from a ferrite core by processing a gap depth to the prescribed dimension after heat treatment at the temperature higher than the slow cooling point of the mold glass before making the gap depth of the magnetic core block to the prescribed dimension. CONSTITUTION:A ferromagnetic thin film 14 with saturation magnetic flux density higher than the magnetic core is provided on at least one of the gap opposite surfaces of a pair of magnetic cores 11 and 12, forming a magnetic core block 17 while jointing mold glass 16 through the magnetic gap of the nonmagnetic material 15. In this case, before making a gap depth H of the magnetic core block 17 to the prescribed dimension, the heat treatment is performed at the temperature higher than the slow cooling point of the mold glass 16 and the gap depth H is processed to the prescribed dimension. Thus, the stress caused by the magnetic cores 11 and 12 is eliminated by the difference of the heat expansion coefficient, the magnetic head with high gap strength and high performace is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a composite type magnetic head used in a high density magnetic disk device or the like.

[0002]

2. Description of the Related Art In recent years, with the increasing density of magnetic disk devices, metal thin film disks having high coercive force and high residual magnetic flux density have been used as magnetic disks. A provided composite magnetic head, a so-called MIG (Metal In Gap) head, is used.

A conventional composite magnetic head will be described below. As shown in FIG. 2, the ferromagnetic oxide MnZ
It is composed of a magnetic core 1 made of n-ferrite or NiZn ferrite and forming a slider portion, and a magnetic core 2 forming a winding portion. FeAlS is formed on the gap facing surface of the magnetic core 2.
A ferromagnetic thin film 3 having a saturation magnetic flux density higher than that of a magnetic core 2 made of an i-based alloy, FeNi or the like is provided and joined by a mold glass 5 via a magnetic gap formed by a non-magnetic material 4 such as SiO ₂ . Winding 6 is applied. There is also a double-film type composite magnetic head in which ferromagnetic thin films are arranged on the surfaces of the magnetic core 1 and the magnetic core 2 that face each other.

Recording is performed by passing a current through the winding 6 to generate a magnetic field from the magnetic gap to magnetize the magnetic disk. Further, reproduction is performed by detecting the magnetic flux generated from the residual magnetism of this magnetic disk.

A conventional method of manufacturing the above-mentioned composite magnetic head will be described. A pair of magnetic cores 1 shown in FIG.
As shown in FIG. 3B, the winding grooves and the gap depth regulating groove 13 are formed in the magnetic core 12 by using Nos. 1 and 12,
After the gap facing surface is mirror-finished, as shown in FIG. 3C, the ferromagnetic thin film 1 such as FeAlSi is formed on the gap facing surface.
4 is provided, and a non-magnetic material 15 such as SiO ₂ that forms a magnetic gap is formed thereon. After that, as shown in FIG. 3D, the gap facing surfaces of the magnetic core 11 and the magnetic core 12 are aligned with each other, and the mold glass 16 is inserted into the winding groove.
Heat treatment is performed at a predetermined temperature to form a gap to form the magnetic core block 17. Next, as shown in FIG. 3E, the gap depth H is processed to have a predetermined dimension on the surface 18 side facing the magnetic disk and on the opposite side to form a recess 19. As shown in FIG. 3F, the composite magnetic head element body 20 is cut, and then, as shown in FIG. 3G, the composite magnetic head is processed into a predetermined shape to obtain the composite magnetic head unit 10.

The above-described conventional manufacturing method is the same as the so-called ferrite head manufacturing method in which the magnetic core is formed only of the ferrite material, and is not a manufacturing method specific to the composite magnetic head.

In the composite magnetic head, the gap is formed at a temperature of 500 ° C. to 600 ° C. which is about 100 ° C. lower than that of the conventional ferrite head due to the problem of pseudo gap. Therefore, mold glass 1
Glass having a low softening temperature is used as 6, and lead-based low-melting glass having a composition containing a large amount of lead is mainly used. However, when the amount of lead increases, the strength of the mold glass itself becomes weak, and as a result, the gap strength becomes insufficient and the magnetic core separates from the gap facing surface during processing or during winding, resulting in poor yield. Therefore, the strength is not lowered by adjusting the components of the mold glass 16.

Further, in the single magnetic head 21, a thermal history of gap formation is added, so that a difference in thermal expansion coefficient between the ferrite material used for the magnetic core and the mold glass 16 becomes a problem. The thermal expansion coefficient α _G of the normal mold glass 16 is 2 more than the thermal expansion coefficient α _{F of} ferrite.
~ 5 (* 10 ^-7 / deg) Small value is selected.

Further, in the case of the composite type magnetic head, there is a problem that the coefficient of thermal expansion of the mold glass 16 changes from its original value. Using two types of mold glass A and B having a coefficient of thermal expansion shown in (Table 1) and a ferrite material, a rectangular ferrite bar 7 as shown in FIG.
The groove 8 was processed.

[0010]

[Table 1]

FeAlSi and a non-magnetic material for forming a gap are formed on the groove 8 by a sputtering method, and a mold glass 9 is put in the groove 8 and heat treatment is performed under the same conditions as the gap formation. Measure the change in the warp of the ferrite bar 7 before and after heat treatment at that time,
The result is shown in FIG. As can be seen from FIG. 5, FeA
When 1Si and the gap material are not formed, the amount of change in warpage matches the difference in the coefficient of thermal expansion. On the other hand, when the film is formed, mold glass A shows a large amount of change in warpage and ferrite. It is shown that a large compressive stress acts on. On the contrary, in the mold glass B, the amount of change in the warp is small due to the film formation, and the stress on the ferrite is also small. As described above, in the case of the composite magnetic head, it is understood that the stress exerted on the ferrite changes depending on the thermal expansion coefficient of the mold glass.

Further, the gap strength (g) of the composite type magnetic head prepared by using the mold glasses A and B is shown in (Table 1).
Also described in. As shown in FIG. 6, the measured value of the gap strength is the transverse rupture force obtained by pushing the magnetic core 2 on the winding side in the direction indicated by arrow A. As can be seen from (Table 1), even if there is not much difference in the coefficient of thermal expansion from ferrite as in mold glass B, the gap strength is weak and the actual mass productivity becomes poor. In addition, when the components are adjusted to increase the gap strength as in the mold glass A, the coefficient of thermal expansion also changes, the stress on ferrite increases, the magnetic characteristics of ferrite deteriorate, and the reproduction efficiency decreases. This causes a problem, and it becomes very difficult to select a mold glass that satisfies both the gap strength and the thermal expansion coefficient.

Further, it is already known that in the manufacturing process of the magnetic head, the heat treatment is performed after the gap depths are all processed to a predetermined size (for example, Japanese Patent Laid-Open No. 6-58242).
3-222309).

[0014]

However, in the above-described conventional manufacturing method, the stress is removed from the magnetic core by heat treatment, so that the magnetic core is deformed. There is a problem in that it causes trouble, in the case of a sliding type magnetic head, the contact state with a recording medium deteriorates, and in some cases, a head crash occurs.

The present invention solves the above-mentioned conventional problems, and provides a method of manufacturing a high-performance composite magnetic head which facilitates selection of mold glass, has a strong gap strength, and is excellent in mass productivity. To aim.

[0016]

In order to achieve this object, a method of manufacturing a composite magnetic head according to the present invention provides a saturation magnetic flux density higher than that of a magnetic core on at least one of the gap facing surfaces of a pair of magnetic cores. When forming a magnetic core block by arranging a ferromagnetic thin film having the magnetic thin film and bonding the thin film with a mold glass via a magnetic gap of a non-magnetic material, before forming the gap depth of the magnetic core block to a predetermined dimension, This is a method in which the gap depth is processed into a predetermined dimension after heat treatment is performed at a temperature higher than the annealing point.

[0017]

By this method, the stress generated from the magnetic core due to the difference in the coefficient of thermal expansion is removed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The composite magnetic head of one embodiment of the present invention is
The description is omitted because it is the same as the conventional example described in FIG.

A method of manufacturing the composite magnetic head according to the embodiment of the present invention will be described below. In FIG. 1 showing an embodiment of the present invention, the same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 1, the difference from the conventional manufacturing method described with reference to FIG. 3 is that after the magnetic core block 17 created with the dimension H of the gap depth of FIG. 1 (e) is heat-treated using an electric furnace or the like, This is the point where a step of re-dimensioning the gap depth is inserted. The heat treatment of FIG. 1 (e ₁ ) is performed at a temperature higher than the annealing point of the mold glass 11 used for forming the gap. Here, the annealing point is a temperature 5 to 10 ° C. higher than the temperature (transition point) at which log η = 13.3, where η is the viscosity of glass.

Further, if the heat treatment temperature is raised too much, the mold glass 16 is softened and the gap length is changed. Therefore, it is preferable to set the temperature below the temperature (Mg point) at which log η = 11.0. In this example, heat treatment was performed for 30 minutes at a temperature higher by 10 ° C. than the transition point which is the slow cooling point of the mold glass 16 used.

By performing the heat treatment, the stress applied to the ferrite magnetic cores 11, 12 is removed and the magnetic cores 11, 12 are deformed.
(E ₂ ) The gap depth is machined to a predetermined size by machining.

The characteristics of the composite magnetic head manufactured by the manufacturing method of this embodiment will be described below.

[0024] (Table 2) embodiments shown in the sample column of Figure using the ferrite and molded glass A shown in (Table 1) 1 (e ₁₎ was created by performing the above heat treatment in the heat treatment, the conventional In Example 1, the ferrite shown in (Table 1) and mold glass A were used, but the conventional method shown in FIG. 2 was prepared without heat treatment. In Conventional Example 2, the ferrite shown in (Table 1) was used. The mold glass B is used and is not heat-treated as in the first conventional example.

Using these composite magnetic heads, 3.5
An output of 4 MHz was measured under the conditions of an inch magnetic disk radius of 22 mm and 3600 rpm. The gap strength was also measured. The measurement results are shown in (Table 2).

[0026]

[Table 2]

As is clear from (Table 2), by performing the heat treatment, the output is 25% while maintaining the gap strength.
It can be seen that it also improves. This output is about the same as that of the second conventional example, but the gap strength is more than double and a high performance composite magnetic head excellent in mass productivity can be obtained.

Although the mold glass 16 has been focused on in the embodiment, the same can be said when the mold glass 16 is fixed and the coefficient of thermal expansion of ferrite is changed. If the difference in expansion coefficient becomes large, stress is applied to the ferrite and the characteristics deteriorate, but by removing the stress from the ferrite by the manufacturing method of the present invention, a high-performance composite magnetic head can be obtained. Therefore, it is possible to further improve the performance by using single-crystal ferrite with less noise as the magnetic cores as the magnetic cores 11 and 12.

[0029]

As is apparent from the above description of the embodiments, the present invention provides a ferromagnetic thin film having a saturation magnetic flux density higher than that of the magnetic cores on at least one of the gap facing surfaces of the pair of magnetic cores. When forming a magnetic core block by joining with a mold glass via a magnetic gap of a non-magnetic material, heat treatment at a temperature higher than the annealing point of the mold glass before setting the gap depth of the magnetic core block to a predetermined dimension. After that, by processing the gap depth to a predetermined size, the problem of selecting mold glass and ferrite material due to the gap strength and the thermal expansion coefficient, which are problems in the manufacture of the composite magnetic head, is eliminated, and the gap strength is improved. It is possible to realize a method of manufacturing an excellent composite magnetic head with high performance in which stress is removed from ferrite, which is strong and has good mass productivity.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating steps of a method of manufacturing a composite magnetic head according to an embodiment of the present invention.

FIG. 2 is a perspective view of a composite type magnetic head.

FIG. 3 is a perspective view illustrating the steps of a conventional method for manufacturing a composite magnetic head.

FIG. 4 is an exploded perspective view showing a sample used for measuring a stress applied to a ferrite material by a mold glass.

FIG. 5 is a graph showing the difference in stress (amount of change in warpage) that the ferrite material receives from the mold glass depending on the thermal expansion coefficient.

FIG. 6 is a perspective view showing the preparation of a sample when measuring the gap strength.

[Explanation of symbols]

 11 magnetic core 12 magnetic core 14 ferromagnetic thin film 15 non-magnetic material 16 mold glass 17 magnetic core block

Claims (1)

[Claims] 1. A ferromagnetic thin film having a saturation magnetic flux density higher than that of the magnetic core is disposed on at least one of the gap facing surfaces of a pair of ferromagnetic oxide magnetic cores, and a magnetic gap of a non-magnetic material is interposed therebetween. A composite magnetic head obtained by processing a magnetic core block bonded by mold glass, wherein the magnetic core is heated at a temperature higher than an annealing point of the mold glass before the gap depth of the magnetic core block is set to a predetermined dimension. A method of manufacturing a composite magnetic head, wherein the gap depth is processed into a predetermined size after heat treatment of a block.