JP2643382B2 - Magnetic head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head, and more particularly, to a magnetic head used in a magnetic recording / reproducing apparatus such as a VTR.

2. Description of the Related Art Ferrite has been used as a core material for magnetic heads in the past. However, with the recent demand for high recording density, high coercive force of recording media, and high output of magnetic heads, high saturation magnetic flux density has been required. A magnetic head using a metallic magnetic material such as sendust or an amorphous alloy having the above characteristics has been studied. Among them, amorphous alloys have excellent mechanical properties such as corrosion resistance and wear resistance, and are promising as materials for high-performance magnetic heads.

Generally, in assembling a magnetic head, a pair of magnetic core halves are joined on a gap surface by fusing glass from the viewpoint of reliability such as gap strength and yield. However, when an amorphous alloy is used for the magnetic core, the high melting point glass conventionally used in ferrite heads cannot be used in consideration of its magnetic properties. In general, the magnetization of an amorphous alloy becomes zero at the Curie temperature Tc, and the magnetization reappears near the crystallization temperature Tx.
Considering the operation as a magnetic head, it is desirable that the magnetic permeability is high. In order to obtain a high magnetic permeability, it is necessary to remove the magnetic anisotropy of the magnetic film by performing a heat treatment in a temperature range of Tc or lower and Tx or lower. At a temperature equal to or higher than Tx, the amorphous alloy crystallizes and the magnetic permeability decreases. Practically, Tx is usually 500 ° C. to 600 ° C., and Tc is 500 ° C. or less in consideration of saturation magnetic flux density as a magnetic head material. Therefore, low melting point lead glass having a low softening point is generally used as the glass used for gap joining of the head half using an amorphous alloy. To lower the softening point, the content of lead in the glass may be increased. However, if the content is increased, the glass itself becomes unstable and the mechanical strength is lowered. For this reason, currently the softening temperature is 400 ℃
Low melting point glass of from 500 ° C to 500 ° C is practically used.

As described above, the bonding at the gap surface of a magnetic head using a conventional amorphous alloy requires the use of a low-melting glass because the crystallization temperature Tx of the amorphous alloy is 500 ° C to 600 ° C. The low mechanical strength of the low-melting glass causes cracks at the gap surface during machining, lowering the head yield and weakening the strength at the head gap. Many problems such as chipping occurred.

An object of the present invention is to provide a magnetic head that solves such a conventional problem.

Means for Solving the Problems In the magnetic head of the present invention, the magnetic gap is composed of crystallized glass and another nonmagnetic material, and the nonmagnetic material and the crystallized glass are sequentially applied to the head core half. The thickness of the crystallized glass on the side of at least one of the head core halves is 300 angstrom or more, and the head core is made of an amorphous alloy.

The crystallized glass formed by sputtering on the non-magnetic material on the gap surface is initially in an amorphous state. Then, in the heat treatment step of joining the two head core halves at the gap surface, the amorphous crystallized glass formed on the non-magnetic material on the gap surface is first melted to form the two head core halves. After joining, crystal nuclei are partially generated, and crystallization proceeds entirely, so that the strength of the glass increases.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a magnetic head according to an embodiment of the present invention, and FIG. 2 is a top view of the magnetic head.

In FIG. 1, a head core 3 having a winding hole 4 is made of a bulk magnetic material such as ferrite, sendust, amorphous alloy, or the like. , And a closed magnetic circuit is formed via an operating gap.

The working gap is a non-magnetic material 1 such as silicon dioxide or high melting point glass formed on the gap surface of the head core 3 by sputtering or CVD, and a crystallization formed on the non-magnetic material 1 by sputtering or CVD. It is composed of glass 2. The non-magnetic material 1 formed on the gap surface functions to prevent the magnetic material on the gap surface from being eroded by the crystallized glass 2 having a low melting point and causing its magnetic properties, particularly the magnetic permeability, to decrease.

The crystallized glass 2 formed on the non-magnetic material 1 has PbO-S
iO ₂ -based crystallized glass is used. The crystallized glass 2 is amorphous when a film is formed on the non-magnetic material 1 on the gap surface, but crystal nuclei are generated on the gap surface in the process of forming the gap by abutting and heating the film. Crystallization proceeds between the butted crystallized glasses, and finally a strong bond is formed between the butted crystallized glasses. Further, the generation of crystal nuclei of the crystallized glass depends on the ambient temperature, pressure and the thickness of the crystallized glass when forming the gap.
When a gap is formed at an ambient temperature within a range in which the magnetic properties of the magnetic material used in the head core do not deteriorate, if the thickness of the crystallized glass is 300 Å or more, these crystal nuclei are generated and the gap surface is formed. Increases the bonding strength.

That is, the crystallized glass formed on the non-magnetic material on the gap surface by sputtering is initially in an amorphous state. Then, in the heat treatment step of joining the two head core halves at the gap surface, the amorphous crystallized glass formed on the non-magnetic material on the gap surface is first melted to form the two head core halves. After joining, crystal nuclei are partially generated, and crystallization proceeds entirely, so that the strength of the glass increases.

However, according to experiments performed by the present inventors, it has been found that the degree of crystallization when heating is performed under certain conditions largely depends on the thickness of crystallized glass. That is, 100, 200, 30
After holding a sample on which a crystallized glass layer having a thickness of 0, 400, and 500 angstroms was formed at a temperature slightly lower than the crystallization temperature of the crystallized glass for a certain period of time, observing the state of generation of crystal nuclei, 100, No crystal nuclei were observed in the 200 angstrom sample, and crystal nuclei were observed in the 300 angstrom thick sample. Furthermore, FIG. 3 shows the results of trial production of magnetic heads using crystallized glass of each thickness for the gap and measuring the force at the time of breaking at the gap surface. In the measurement, a fixed core was fixed, and a load was applied to a position separated by a certain distance from the gap of the other core, and the joint strength was defined as a force when the core was broken at the gap surface. From this result, the thickness of the crystallized glass on the non-magnetic material
If the thickness is 300 Å or more, crystal nuclei are generated in the gap joining process, and the gap joining can be performed using crystallized glass at the same temperature as the amorphous glass, and the strength is increased by crystallization after the joining. , The bonding strength at the gap surface of the head core is increased, and the production yield of the head and the reliability of the head are dramatically improved. The non-magnetic material between the crystallized glass and the gap surface of the head core half has an effect of preventing the crystallized glass and the magnetic material constituting the head core from reacting during the heat treatment to prevent the magnetic properties from deteriorating.

The magnetic head produced in this manner has a high gap length accuracy because the gap is unlikely to be loosened, and its recording / reproducing characteristics match the recording density characteristics expected from the total thickness of the gap material.

Therefore, the magnetic head of the present embodiment has a strong joint even in a narrow gap, forms a stable magnetic gap, and has a high-performance and highly-reliable structure.

Effect of the Invention As described above, according to the present invention, bonding at the gap surface of the head core is performed by using crystallized glass on a non-magnetic material formed on the gap surface of the head core. As the glass itself increases in strength and the strength of the glass itself increases, defects such as gap cracks that occurred during magnetic head processing are reduced, dramatically improving the yield of magnetic head manufacturing and improving the reliability as a head chip. Can be. Further, by preventing the lead in the crystallized glass from diffusing into the magnetic material due to the heat treatment, by using a non-magnetic material provided between the crystallized glass and the gap surface, a high quality gap can be realized.

[Brief description of the drawings]

1 and 2 are a perspective view and a top view, respectively, of an embodiment of the magnetic head of the present invention, and FIG. 3 is a graph showing the relationship between the thickness of crystallized glass and the gap bonding strength of the head. 1 Non-magnetic material 2 Crystallized glass 3 Head core 4 Winding hole 5 Glass

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Eisai Sawai 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In-company (56) References JP-A-55-108922 (JP, A) JP-B-54-2841 (JP, B1)

Claims (2)

(57) [Claims] 1. A magnetic head having a structure in which a magnetic gap is made of crystallized glass and another non-magnetic material, and wherein the non-magnetic material and the crystallized glass are sequentially applied to a head core half, and at least one of them is provided. 3. The magnetic head according to claim 1, wherein the thickness of the crystallized glass on the head core half side is 300 Å or more. 2. The magnetic head according to claim 1, wherein the head core is made of an amorphous alloy.