JPS63281204A - Production of base material for magnetic head core - Google Patents

Abstract

PURPOSE:To suppress the deflection amt. of a substrate on which films are formed by dividing a process for forming alloy films to >=2 processes and subjecting the films to a heat treatment at 300-800 deg.C after the respective processes for the film formation. CONSTITUTION:The base material for a magnetic head core is formed by repeating the operations consisting in subjecting the soft magnetic film having the thickness below a desired film thickness to the heat treatment to relieve stresses after formation of said film and forming the soft magnetic film having the thickness below the desired film thickness further onto the heat-treated soft magnetic film and subjecting the film to the heat treatment in succession thereto at the time of forming the thick soft magnetic films having the physical coeffts. different from the physical coeffts. of the substrate consisting of a brittle material onto said substrate. Namely, the films consisting of the soft magnetic materials are deposited on the substrate consisting of the brittle material by dividing the stage to plural stages without depositing the soft magnetic films at one time on the substrate and further, the films are subjected to the heat treatments at 300-800 deg.C in every stage and, therefore, the mismatching with the underlying layers by thermal stresses, etc., is relieved in the stage of a relatively thin film thickness. The degree of the adhesion of the soft magnetic films attaining the desired film thickness as a whole to the brittle substrate is thereby increased and the breakdown of the brittle substrate and the deflection amt. of the substrate on which the films are formed are suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a magnetic head core base material, and more particularly, to a method for manufacturing a thick film magnetic head core formed using a thin film forming technique such as a vacuum evaporation method or a sputtering method. It is something.

(Prior Art) In recent years, in the field of magnetic recording technology, there has been an increasing demand for increased recording density. One way to increase the density of magnetic recording is to use a metal tube with high magnetic energy or a vapor-deposited tape with low self-demagnetization as the magnetic tape, while on the magnetic head side, the core material is high saturation magnetic flux density, The development of materials with high magnetic permeability is progressing. Since ferrite has a limit in saturation magnetic flux density, alloy materials or amorphous alloy materials are suitable as such core materials. It is well said that the Fe-5i-At alloy has a high magnetic permeability and a high saturation magnetic flux density mainly due to its composition of 9.5 wt% Si, 5.5 wt% At, and the balance Fe.

When creating a magnetic head core, considering the frequency dependence of the magnetic permeability of alloy materials, the magnetic permeability attenuates in the high frequency band due to eddy current loss. Therefore, in order to obtain high magnetic permeability in a high frequency band, a core material is required in which soft magnetic material and nonmagnetic material of several microns are alternately laminated in consideration of eddy current loss. However, it is difficult to produce this laminated core material from a bulk state due to the thickness of the soft magnetic material and poor bonding properties between the magnetic layer and the nonmagnetic layer. Further, from the viewpoint of reproduction sensitivity, the track width is required to be several tens of microns.

Therefore, there is a strong demand for a magnetic head core base material in which a thick soft magnetic film is formed on a brittle material substrate by making full use of thin film forming techniques such as vacuum evaporation.

(Problems to be Solved by the Invention) However, the physical coefficients, such as elastic coefficients and thermal expansion coefficients, differ between the ceramic substrate, which is a brittle material, and the soft magnetic film formed thereon. Due to the incompatibility, stress concentration that is not seen in Lv1 homogeneous materials occurs at the edges of the bonding interface and at the tips of interfacial cracks, and even if the internal stress of the film does not reach the fracture strength of the substrate material, fracture at the heterophase interface region progresses. However, fracture occurred within the substrate along the interface, making it difficult to form a thick film on a brittle material substrate. Furthermore, as the film becomes thicker, even if the internal stress of the film does not change, the total stress of the film increases, and the amount of deflection of the substrate on which the film has been deposited increases.
This makes the subsequent magnetic head manufacturing process difficult.

(Means for Solving the Problems) The present invention provides a method for forming a thick film of a soft magnetic film having a physical property coefficient different from that of the brittle material substrate on a brittle material substrate. After forming the film, heat treatment is performed to relieve stress, and a soft magnetic film having a thickness less than the desired film thickness is further formed on the heat-treated soft magnetic film, and then heat treatment is repeated. to create a magnetic head core base material.

(Function) Instead of depositing a soft magnetic film on a brittle material base material all at once, a film made of a soft magnetic material is deposited in multiple steps,
Furthermore, since heat treatment is performed at each step, mismatches due to thermal stress with the underlying layer are alleviated at the stage of relatively thin film thickness, and when the soft magnetic film reaches the desired film thickness as a whole, it is able to withstand the brittle substrate. The degree of bonding increases, suppressing the destruction of brittle substrates and the amount of deflection of film-formed substrates.

(Example) Hereinafter, the present invention will be described in detail based on an example. FIG. 1 shows the structure of a film-formed substrate having a different phase interface. In the same figure, a Fe-
A Si--At alloy film 2 is formed by electron beam evaporation. The above 20 μm thick Fe-5i-At
When forming the alloy film 2, first 51 is applied on the brittle material substrate 1.
After forming the alloy film 21 with a thickness of μm, it is heat-treated in vacuum at 600° C. for 5 hours to relax the stress, and the heat-treated alloy film 2. An alloy film 2° having the same composition and having a thickness of 5 μm is further formed on top. The stress of the alloy film 22 is similarly relaxed by heat treatment. This process of film formation and heat treatment was repeated four times.
was formed. The relationships between the internal stress of the film and the film thickness and the total stress of the film in each operation at this time are shown in FIGS. 2 and 3, respectively.

As a comparative experiment, 5μm, 10μm, 15μm, 20μm
Fe-5t-At alloy films of various thicknesses were formed by electron beam evaporation on the same brittle material substrate as shown in Fig. 1, and heat treated in vacuum at 600°C for 5 hours. The relationship between the internal stress of the film and the film thickness and the total stress of the film after heat treatment was investigated. The results are shown in FIGS. 4 and 5, respectively.

Comparing Figures 2 and 4, and Figures 3 and 5, the internal stress and total stress after forming the Fe-5i-At alloy film of 20 μm are If heat treatment is performed during the film, the internal stress will be 1.5X1.
0 dVne/crit, total stress is 3 x 106 dyn
The value of e/d is shown, and it can be seen that both the internal stress and the total stress are reduced by about 63% compared to the case where no heat treatment was performed during the process. Furthermore, as shown in Figure 5, the maximum value of the total stress when forming a film up to a thickness of 20 μm is a large value of 8.4XIOd'lne/ca. According to the method of this embodiment shown in FIG.
/-, which is a decrease of about 63% in this example.

(Other Examples) In the above experiment, a 5 μm thick F was deposited on a brittle material substrate.
After forming the e-5i-Al alloy film, S t 02 .

At203. 500 to 3000 non-magnetic materials such as SIC
After film formation in the range A, heat treatment is performed at 600°C for 5 hours in vacuum, and an alloy film and a nonmagnetic film with a thickness of 5 μm are further formed on the nonmagnetic film at 500 to 3000A, and the heat treatment is performed in step 4.
By repeating the process several times, a total of 20 μm thick Fe-
Even when a core material made of a 5i-At alloy film was created, the relationship between film thickness, film stress, and total stress was the same.

That is, when forming a 20 μm thick Fe-5i-At alloy film, when dividing the film-forming process by inserting heat treatment in the middle, a thin non-magnetic film is added on top of the formed Fe-5i-A1 alloy film. is inserted to form a magnetic head core substrate.

Even if a non-magnetic film is inserted in this way, the C-stress relationship is not impaired even if heat treatment is performed midway.

In the magnetic head core substrate in which a nonmagnetic film is inserted as in the above embodiment, the threshold value that causes destruction of the substrate material and film peeling when the Fe-5i-At alloy film is formed on a brittle material substrate is The film thickness that reaches the total stress shifts to the high film thickness side.

This is true, for example, for a soft magnetic film (Fe-5) as shown in Figure 6.
In a magnetic head in which an i-At alloy film) 4 is held between non-magnetic substrates 3 and the thickness of the soft magnetic film 4 corresponds to the track width, it is possible to increase the track width that can be formed. It shows.

(Effects of the Invention) As explained in detail above, a Fe-5i-At based alloy film having a thickness equal to or less than a desired film thickness is formed, heat death treatment is performed, and an additional film is formed on the film after the heat treatment. By repeating the operations of forming islands and applying heat treatment to form a thick film of the desired thickness,
cv, the discrepancy in physical property coefficients between the substrate and the film becomes less of a problem, the range of substrate selection is expanded, magnetic property deterioration due to thermal stress inverse magnetostrictive effect is suppressed, and magnetic property deterioration of the core is prevented.
As a result, the efficiency of the magnetic head can be improved. Furthermore, since the internal stress and total stress of the Fe-5i-At alloy film are reduced, the magnetic head processing process becomes easier, the productivity of the magnetic head can be improved, and the track width can be increased.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a film-formed substrate having a different phase interface according to an embodiment of the present invention, and FIG. 2 is a structural diagram of a Fe-5t-
FIG. 3 is a diagram showing the relationship between the thickness of the At-based alloy film and the internal stress. FIG. 3 is a diagram showing the relationship between the thickness and total stress of the Fe-5i-At-based alloy film according to the same example. FIG. Figure 5 is a diagram showing the relationship between film thickness and stress according to the method for forming a 5i-At alloy film, and Figure 6 is a diagram showing the relationship between film thickness and total stress according to the conventional method for forming a Fe-5i-At alloy film. FIG. 2 is a perspective view of a magnetic head in which a soft magnetic film is sandwiched between nonmagnetic materials. DESCRIPTION OF SYMBOLS 1... Brittle material substrate, 2... Fe-5i-At type alloy film, 3... Nonmagnetic material, 4... Soft magnetic film. Agent Patent attorney Takeshi Sugiyama (1 other person) Film thickness - m
) XIO' Figure 6

Claims (1)

[Claims] (1) In the process of forming a thick Fe-Si-Al alloy film on a brittle material substrate, the process of forming the alloy film is divided into two or more, and after each film forming process, A method for producing a magnetic head core base material, the method comprising performing heat treatment at ℃.