JPS61265715A - Member for magnetic head core - Google Patents

Abstract

PURPOSE:To decrease the camber of a substrate occurring in the residual stress generated between a soft magnetic film and underlying substrate by interposing a film consisting of a high melting material having the coefft. of thermal expansion and thickness to decrease the camber by the residual stress of the underlying substrate between the underlying substrate and soft magnetic film. CONSTITUTION:The film consisting of the high melting material having the coefft. of thermal expansion and thickness to decrease the camber by the residual stress of the underlying substrate is interposed between the underlying substrate and soft magnetic film of a member for a magnetic head core consisting of the underlying substrate and the soft magnetic film formed on the underlying substrate. The soft magnetic film is formed on the underlying substrate on which the high melting material film is formed and therefore the member for the magnetic head core which decreases the chamber of the substrate occurring in the residual stress is produced and the adverse influence on the soft magnetic film is minimized. The adhesion between the substrates is thereby made easy in the subsequent process for working a rotary head and since the adhesion is made possible without exerting the much strain by straightening, the strength of the adhesion is improved.

Description

[Detailed Description of the Invention] Technical Field> The present invention is constructed by forming a high melting point material between a soft magnetic film and a base substrate such as a non-magnetic substrate or a composite substrate made of magnetic and non-magnetic materials. The present invention relates to a member for a magnetic head core.

<Prior Art> Recently, there has been a strong demand for increased magnetic recording density, and magnetic heads are required to have high saturation magnetic flux density, narrow gaps, and narrow tracks. Therefore, in rotary heads such as video tape coder (VTR) heads, narrower tracks are achieved by fabricating soft magnetic materials on non-magnetic substrates by vapor deposition or sputtering, and in the case of thin film heads, integrated is being developed. However, when forming a soft magnetic film on a substrate by vapor deposition or sputtering, (1) residual stress due to the difference in thermal expansion coefficient between the magnetic film and the non-magnetic film, and (2) film formation caused by other reasons. Residual stress is generated after. These residual stresses cause the entire substrate on which the film is formed to warp. This makes it difficult to perform an adhesion process in which a soft magnetic film is sandwiched between nonmagnetic substrates in the process of manufacturing a magnetic core sandwiched between nonmagnetic substrates such as a rotary head.

Furthermore, when forming a thin film integrated head, it causes deterioration in accuracy during pattern processing by photolithography.

<Objective of the Invention> An object of the present invention is to provide a member for a magnetic head core that can reduce warping of a substrate due to residual stress generated between a soft magnetic film and a base substrate.

<Structure of the Invention> In order to achieve the above object, the present invention provides a film made of a high melting point material having a thermal expansion coefficient and thickness that reduces warping due to residual stress in the base substrate between the base substrate and the soft magnetic film. It is characterized by intervening.

In other words, it is difficult to completely match the thermal expansion coefficients of a base substrate such as a non-magnetic substrate and a soft magnetic film. Although it is difficult to reduce the warpage significantly depending on the conditions, the magnetic helad core layer member of the present invention has a thickness and thermal expansion coefficient that reduces warpage of the entire substrate after film formation between the underlying substrate and the soft magnetic film. By inserting a film of a high-melting point material having a high melting point, the subsequent magnetic head manufacturing process is facilitated.

<Example> FIG. 1 is a schematic configuration diagram of an electron beam evaporation apparatus used in manufacturing a FeAfSi vapor deposited film in an example of the present invention. Maintain a high vacuum inside the vacuum pelger 1,
A non-magnetic substrate 2 on which a deposited film is formed, and a heater 3 for heating the non-magnetic substrate 2 are arranged in the upper part of the vacuum pelger 1. As the non-magnetic substrate 2, a photosensitive crystallized lath substrate, a non-magnetic 7-elite, or a ceramic having a thermal expansion coefficient similar to that of Sendust alloy is used. In this example, the non-magnetic substrate has a thermal expansion coefficient of 13.
A crystallized glass substrate of 5×10 −′/deg was used.

At the bottom of the vacuum pellet jar 1, there is a hearth (crucible).
An alloy tablet 5, which is an evaporation source material, is housed in the hearth 4, and the electron beam 7 generated by the filament 6 is bent by the magnetic field and irradiated onto the alloy tablet 5. A shutter 8 is interposed between the hearth 4 and the non-magnetic substrate 2, and the substance evaporated from the alloy tablet 5 is passed through or blocked depending on the opening/closing operation of the shutter 8. The alloy tablet 5 contains 4 wt% of Al<fluminiram) and 27.5 iIl of Si (silicon).
t% and the balance was Fe (iron).

Note that the composition distribution in the film thickness direction of the FeA, gsi vapor deposited film formed on the nonmagnetic substrate 2 is AJ21~10 wL%, Si
The range is 6 to 12 wt%, and the composition of the entire film is A13-6.
wt% and Si in the range of 8 to 12 wt%, a FeA I Si vapor deposited film whose magnetic properties are less affected by residual stress generated between it and the nonmagnetic substrate 2 can be obtained.

Before depositing the FeA, jsi deposited film, that is, the soft magnetic film,
Hf (hafnium) as an example of a high melting point material was deposited on the non-magnetic substrate 2 to a thickness of 500 at a substrate temperature of 400°C. This 400° C. is the same temperature as the deposition process of FeA (Si) deposited film. Such heating of the nonmagnetic substrate 2 is intended to improve the adhesion of the Hf deposited film, and is carried out by the heater 3. be exposed.

Next, in the vapor deposition process of FeA and gsi vapor deposition films, the electric power input to the filament 6 is set to 10 kW, and the electron beam is swept over the entire inside of the hearth 4. Then, FeA IS;
htKr#3)-2F'pA (I Si group Rt
is subjected to heat treatment at 600°C in vacuum. In order to compare the warpage and magnetic properties of a magnetic herad core member in which a FeA I Si vapor-deposited film was deposited on a non-magnetic substrate on which Hf was formed, a non-magnetic substrate of the same quality as above without Hf formed was also used. A magnetic head core member was manufactured by depositing a FeA4Si deposited film having the same composition and the same thickness. FeA of both these
A comparison of the magnetic properties of the 4Si deposited films is shown in Table 1 below. Other FeAl! , the characteristics of the Si vapor deposited film are: saturation magnetic flux density Bs = 11000G, electrical resistance ρ = 70
No difference occurred in μΩcm.

Further, the state of warpage as shown in FIG. 2 at this time was measured as the amount of warpage (b) using Talysurf. The results showed that Hf was evaporated onto the nonmagnetic substrate 2, and FeA
, the amount of warpage (b) of the substrate on which the psi deposited film is formed is F
It was 1/3 that of the case where the eAl5i film was directly formed on the non-magnetic substrate 2. In addition, the magnetic properties at that time are
Undamaged as shown in Table 1.

As mentioned above, the composition of the FeA4Si vapor deposited film has a composition distribution in the film thickness direction of Ap 1 to 10 wt%, Si 6 to 12
The overall composition of the film is Af3-6w.
t%, and is controlled within the range of 518-12wt%, in order to reduce the influence of residual stress on magnetic properties.

In general, when selecting a high melting point material, the shape of the substrate depends on whether the entire substrate will be concave or convex toward the film formation side when a soft magnetic film is formed on a nonmagnetic substrate without intervening a high melting point material. Decide whether the coefficient of thermal expansion of the high melting point material should be large or small relative to the coefficient of thermal expansion. Further, the thickness of the high melting point material needs to be determined based on the degree of warpage of the entire substrate after the soft magnetic film is formed and heat treated. Further, the reason why a high melting point material is used here is to minimize the influence of the underlying substrate on the soft magnetic material during the heat treatment process. In this embodiment, the soft magnetic film and the high melting point material are formed by electron beam evaporation, but there will be no problem in implementing the present invention if the film is formed by sputtering or the like.

<Effects of the Invention> As described above in detail, according to the present invention, since a soft magnetic film is formed on the base substrate on which the high-melting pre-material film is formed, warping of the substrate due to residual stress is avoided. It is possible to produce a magnetic rad core layer member with a small amount of magnetic flux, and to minimize the adverse effects on the soft magnetic film. This means that in the subsequent rotary head processing process, the substrates can be bonded easily and without adding much strain due to straightening, which improves the bonding strength and, therefore, improves reliability for narrow gap formation. This makes it possible to realize a magnetic head that is compatible with high magnetic recording density. In addition, even in the case of a highly integrated thin film head, the processing accuracy is improved in the subsequent processing process.
A thin film head with a higher degree of integration can be realized. Particularly, the present invention is effective when producing a thick soft magnetic film that exhibits large warpage.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an electron beam evaporation apparatus used in one embodiment of the present invention. FIG. 2 is a diagram showing a method for measuring substrate warpage. 1... Vacuum Pelger, 2... Substrate, 3... Heater, 4... Hearth, 5... Alloy tablet, 6...
- Filament, 8...Shutter, 9...Soft magnetic film.

Claims (1)

[Claims] (1) In a magnetic head core member consisting of a base substrate and a soft magnetic film formed on the base substrate, a thermal expansion coefficient that reduces warpage due to residual stress in the base substrate between the base substrate and the soft magnetic film. A member for a magnetic head core, characterized in that a thick film of a high melting point material is interposed therebetween.