JPH0250524B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an improvement in a method for manufacturing a magnetic head, and more particularly to a method for manufacturing a magnetic head that enables gap formation with high precision and reliability. [Prior art] As a method of forming a gap in a magnetic head,
A glass material is attached to the front gap forming surfaces of the two ferrite cores by sputtering so that the total film thickness is equal to a predetermined gap width, and the two cores are placed so that the front gap forming surfaces thereof face each other with the glass layer interposed therebetween. A method of forming a gap within the range of the softening temperature and melting temperature of the glass after pressing the glass is disclosed in Japanese Patent Publication No. 47-26336.
It is disclosed in the publication No. However, in this case, all of the glass between the front gap constituent surfaces of the two cores is softened by the heat treatment performed within the range of the softening temperature and melting temperature of the glass, making it difficult to achieve uniform adhesion over the entire surface. Another drawback is that it is not possible to reduce variations in gap accuracy, and when a glass layer is formed by a high-speed sputtering method (magnetron sputtering method, etc.), bubbles are generated within or on the surface of the glass layer. Problems have arisen, such as strength problems or fragments of the magnetic recording medium entering the bubbles during use as a magnetic head, causing deterioration of characteristics. [Problems to be Solved by the Invention] The latter problem is particularly important when manufacturing floppy disk or hard disk heads, which have wider gap lengths than video heads, from the viewpoint of productivity, and the high-speed sputtering method is not suitable. It is essential to apply
As a result, the proportion of bubbles generated within or on the surface of the glass layer increases rapidly, and the inventors believe that this is an important problem that must be solved in practice, and after conducting extensive studies, the inventors have developed the present invention. This is what led to this. The present inventors have discovered that the above air bubbles are caused by Ar occluded in the glass layer during high-speed sputtering, which forms air bubbles within or on the surface of the glass layer after bonding during heat treatment for thermocompression bonding of the glass layers. We have confirmed that this is due to the above, and have arrived at the present invention. The present invention provides a method for manufacturing a magnetic head that is free from air bubbles in the gap portion after bonding and enables gap formation with high precision and reliability. [Means for Solving the Problems] In the present invention, a SiO ₂ film is applied as a first layer, and a glass layer is applied as a second layer on the gap forming surfaces of the two assembly pieces forming the gap of the magnetic head. Formed sequentially by high-speed sputtering method, then Ar-free
Heat treatment for the second layer glass to the softening temperature or
After 15 minutes to 1 hour at a temperature between 950°C,
By stacking the gap-forming surfaces of the assembly pieces that are to be assembled together facing each other and heating them while applying pressure, the glass films serving as the second layer of the two assembly pieces are bonded together, and the magnetic field of the gap portion is Reinforced glass is bonded to the opposite side of the surface facing the recording medium. The film thickness ratio of SiO ₂ film and glass film is 10:1 to
10:4 is appropriate. [Function] According to the study by the present inventors, Ar taken into the glass film or SiO ₂ film during high-speed sputtering is
It is released by heating the glass film or SiO ₂ film, but in order to emit it to a level that is practically acceptable for use as a magnetic head, it is necessary to remove the second layer of glass after sputtering and before the bonding process of the glass films. between the softening temperature and 950°C, preferably between 100°C and 870°C higher than the softening temperature of the second layer glass,
It was found that heating for 15 minutes to 1 hour was sufficient. The reason why the sputtered film is a composite layer of the first layer, which is an SiO ₂ film, and the second layer, which is a glass film, is as follows. That is, when the sputtered film is made of only a glass film, the glass film is softened during the Ar removal heat treatment, and
The uniformity of the film thickness is already lost before the glass film bonding heat treatment, and the gap length of the actual product increases with respect to the target gap length after glass _film bonding. This is because it is necessary to have a two-layer structure. Also, 2 like this
Due to the layered structure, the gap length matches the target value during heat treatment for bonding the glass films, there is little variation, and the bonding strength at the gap portion is increased. [Example] Next, an example of the present invention will be described. 1st
As shown in the figure, in the ferrite cores 11 and 12,
A SiO ₂ film 4 and a glass film 5 are each formed in sequence by magnetron sputtering. For a gap length of 2 μm, the SiO ₂ film has a gap length of 8000 Å, and the glass film has a gap length of 8000 Å.
It was formed to a thickness of 2000 Å. The ferrite cores 11 and 12 are brought into contact with each other, the reinforcing glass 6 is set, and the ferrite cores 11 and 12 are heated at 850°C.
The gap of the magnetic head was formed by heating the magnetic head while pressing it. FIG. 2 shows the viscosity characteristics of the glass of the glass film 5 used for adhesion and the reinforced glass 6. By using glasses with different viscosities as described above, in particular, by using a glass with a higher viscosity at the pressure bonding heating temperature than the glass film 5 as the reinforcing glass 6, it is effective to suppress the reaction of the glass in the apex portion. It was hot. FIG. 3 shows a diagram after the gap is formed in the apex portion using the conventional method, that is, when the same glass is used for the glass film 5 and the reinforcing glass 6, and
A partial schematic diagram of this embodiment is shown as a. FIG _. 4 shows the ratio tglass/(tglass+
FIG. ₂ is a diagram showing how the ratio of gap length defects to the target gap length depends on tsio 2). tglass/tglass+tsio ₂ ) can form a gap with little variation up to approximately 0.4. FIG. 5 shows how the gap strength depends on tglass/tglass+tsio ₂ . When tglass/tglass+tsio ₂ is about 0.1 or more, a gap can be formed with greater strength than in the conventional method. As you can see from the above, tglass/tglass+tsio ₂
In the range of 0.1 to 0.4, it is possible to form a gap with better accuracy and strength than before. Table 1 compares how the difference between the optical gap length and the effective gap length is improved compared to the conventional method.

[Table] [Effects of the Invention] As explained above, according to the present invention, there is an effect that gap formation with higher strength and higher precision can be obtained with less variation than the conventional method.

[Brief explanation of drawings]

FIG. 1 is a gap forming process diagram according to the present invention;
Figure 2 is a diagram showing the viscosity characteristics of bonded glass and reinforced glass, Figure 3 is a schematic diagram of the airpex part, and Figure 4 is a diagram showing the viscosity characteristics of adhesive glass and reinforced glass.
Figure 5 shows the thickness of the second glass layer and the defective rate, respectively.
It is a figure showing the relationship of strength. 11, 12: Ferrite core, 4: SiO ₂ film,
5: Glass film, 6: Reinforced glass.

Claims (1)

[Scope of Claims] 1. A SiO ₂ film is applied as a first layer to each of the gap forming surfaces of the assembled pieces forming the gap of the magnetic head.
A glass film is sequentially formed as a second layer by a high-speed sputtering method, and the gap-forming surfaces of the two assembly pieces that are to be assembled are placed on top of each other facing each other, and the second layer is heated while being pressurized. In the case where two layers of glass films are bonded together and a reinforcing glass is bonded to the opposite side of the surface facing the magnetic recording medium of the gap part, after sputtering and before the step of bonding the glass films together, the second layer is bonded. At a temperature between the softening temperature of layered glass and 950℃,
A method for manufacturing a magnetic head, characterized in that heat treatment is performed to release Ar that has entered the SiO ₂ film and the glass film by sputtering for 15 minutes to 1 hour. 2. The method of manufacturing a magnetic head according to claim 1, wherein the heat treatment for releasing Ar is performed at a temperature of 100°C higher than the softening temperature of the glass film to 870°C. 3 The ratio of the film thickness of the first layer and the second layer is 10:1 to 10:1.
10. The method of manufacturing a magnetic head according to claim 1, wherein the ratio is 10:4.