JPH0319109A - Magnetic head - Google Patents

Abstract

PURPOSE:To deteriorate the occurrence ratio of a defect owing to a crack by specifying an angle which a surface accumulating a magnetic thin film and the edge surface of a head make on a medium sliding surface. CONSTITUTION:A track groove is worked for a ferrite piece 2, and sendust films 3 and 3' are respectively formed, whereby both core half bodies are jointed by melting glass 4. The range of the angle theta1 which the thin film forming sur face and the both sides of a core chip make is set to be 50-80 deg.. In such a case, distortion owing to thermal stress which occurs in accordance with the differ ence of a linear expansion coefficient between an oxide magnetic block 2 and the magnetic thin film 3 moves in a direction almost parallel to a head side. Thus, the occurrence ratio of the defect owing to the crack is deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head suitable for recording and reproducing high frequency signals, and particularly to a composite magnetic head suitable for high coercive force recording media.

[Prior Art] Due to the demand for higher density magnetic recording, it is advantageous to increase the coercive force of a magnetic recording medium. For example, in order to record signals on a high coercive force magnetic recording medium such as a metal tape, A magnetic field of high strength and sharp distribution is required, and therefore the material of the magnetic head is also required to have a high saturation magnetic flux density (Bs). For example, in ferrite material, B
s is 4,500 to 5,000 Gauss, and there is a limit to the strength of the recording magnetic field that can be obtained, and the coercive force of the magnetic recording medium is 1,000 Gauss.
If it exceeds 00e (Oersted), the recording is insufficient. On the other hand, Fe-A, which is a generic name for metal magnetic materials,
Crystalline alloys such as I-Si alloy Ni-Fe alloy, or Co-Nb-Zr, Co-Ta-Zr, Co-To-H
Magnetic heads using amorphous alloys such as F generally have superior properties such as higher Bs and lower sliding noise than ferrite materials. However, when the film thickness is 10 μm or more, the effective magnetic permeability at high frequencies (5 MHz) is lower than that of ferrite due to eddy current loss, which has the disadvantage of lowering the regeneration efficiency. In addition, it is inferior to ferrite material in terms of wear resistance.

Therefore, in order to solve the above-mentioned drawbacks, ferrite material and magnetic fi! The so-called metal-in-gap (MI) is a combination of two films, and a magnetic thin film is formed using vacuum thin film formation technology in the vicinity of the gap of a magnetic core mainly made of ferrite material.
G) Composite heads called heads have become mainstream.

FIG. 8 is a diagram showing the structure of the main part of the magnetic medium sliding surface of the conventional MIG head mentioned above, in which 2 and 2 degrees are blocks made of ferrite material, and 3 and 3 degrees are the ferrite blocks 2 and 2.゜ is the sendust thin film deposited on top, 4 is the bonding glass, and g is the magnetic gap. In the manufacturing process of this type of head, a large number of head chips can be obtained by slicing a magnetic block in which the structure shown in FIG. 8 repeats in a direction parallel to the gap. [Problems to be Solved by the Invention] However, in the MIG head constructed as described above, when cutting by the slicing process, the sendust thin film, ferrite, Since the welded glass is directly cut at the same time, the strain caused by the difference in thermal expansion coefficient between the sendust thin film and the ferrite is released, and there is a gap between the sendust thin film and the ferrite as shown in FIG. There is a problem in that cracks as shown at 6° occur.

In view of this background, the present invention is a magnetic head consisting of a pair of core halves each having a magnetic thin film of high saturation magnetic flux density deposited on the end face of an oxide magnetic block, which significantly reduces the failure rate due to cracks. This paper presents a novel magnetic head structure that can reduce the noise level.

[A Thousand Steps to Solve the Problems] For this purpose, according to the magnetic head of the present invention, the angle between the surface on which the magnetic thin film is deposited on the medium sliding surface and the end surface of the head is It is set at 50° to 80”.

[Function] According to the magnetic head configured as described above, cracks occur because the strain due to thermal stress generated due to the difference in linear expansion coefficient between the oxide magnetic block and the magnetic thin film moves in a direction nearly parallel to the side surface of the head. rate has decreased significantly.

[Example] Examples of the present invention will be described below.

FIG. 1 is a diagram showing the main structure of a magnetic medium sliding surface of a magnetic head as an embodiment of the present invention, and the same components as in FIG. 8 are given the same reference numerals. The difference from the magnetic head in FIG. 8 is that the angle θ between the deposition surface of the magnetic thin film 3,3° and the end face of the head is set to a larger angle θ1 than 00 in the magnetic head in FIG. .

A prototype magnetic head for an FDD (floppy disk drive) having such a structure of the sliding surface of the medium was fabricated and evaluated.

The manufacturing process will be explained below using FIGS. 2 to 7.

First, as shown in FIG. 2, the ferrite piece 2 is finished with mirror lapping, and the track grooves 1 that regulate the track width are processed using a rotary grindstone.

Next, as shown in Fig. 3, a winding groove 5 into which the coil bobbin is inserted is provided. Thereafter, the sendust film 3 is applied to the block in FIG. 2 and the block in FIG. 3 by sputtering, respectively.
．． A film of 10 μm is formed at each angle of 3°. Furthermore, a film of S i O 2 (0.11 μm) having the same thickness of 3.3° was formed on each film, and the two blocks were butted against each other through this film as a magnetic gap material, and both core halves were bonded together using the welding glass 4. By joining, a block as shown in FIG. 4 is obtained. Subsequently, the medium sliding surface is lapped to a mirror finish, and a back groove 6 is formed as shown in FIG. 5. After this, the core chip is cut along the dashed line a to obtain a core chip as shown in FIG.

In the FDD head, both sides of this core chip (
(corresponding to the end surface of the head in the present invention) is finished with a mirror wrap and is sandwiched between 5.5° ceramics called sliders as shown in FIG.

Now, the head can be manufactured in this way,
Figure 1. The angle (θ) between the thin film forming surface and both side surfaces of the core chip as shown in FIG. We investigated the situation. Note that since this θ is determined by the shape of the rotary grindstone that regulates the track width, it is possible to freely shape the track width.

Table 1 As shown in Table 1, the incidence of cracking is extremely high when θ is between 30” and 45°, but it rapidly decreases when the angle exceeds 70°. In what process does this type of cracking occur? I checked to see if it did.

It was found that most of the results occurred during the process of slicing the core into single pieces. The reason seems to be that thermal stress is generated after the glass is welded due to the difference in linear expansion coefficient between the sendust film, which is a metal magnetic thin film, and ferrite, and the stress is removed by slicing.

Therefore, as shown in FIG. 8, the angle θ formed between this film-forming surface and both side surfaces is made smaller. In this case, the strain due to thermal stress acts in a direction close to perpendicular to the side surface (as shown in FIG. 8, X), which tends to cause cracks.

On the other hand, if the angle θ is set to a large angle θ1 as shown in FIG. 1, the strain acts in a direction close to parallel to the side surface of the core (as shown by x1 in FIG. 1), making it difficult for cracks to occur.

Here, the setting of θ1 is set to 50'' or more, allowing for a cracking occurrence rate of around 10% from Table 1.

Further, it is desirable to set the angle to 80 degrees or less so that the boundary between the ferrite and the sendust film does not act as a pseudo gap and electromagnetic conversion does not occur between the sendust films 3 and 3' outside the track width. Therefore, the ideal range of θ1 is 50° to 80°. Although the above embodiment has been explained by taking an FDD head as an example, the present invention can of course be applied to heads for other uses such as a VTR head and similar effects can be obtained.

[Effects of the Invention] As explained above, according to the structure of the magnetic head of the present invention,
The defect rate during manufacturing can be significantly reduced, and a magnetic head that is inexpensive and highly mass-producible can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main structure of a magnetic medium sliding surface of a magnetic head as an embodiment of the present invention, and FIGS. 2 to 7 are manufacturing of a magnetic head for FDD as an embodiment of the present invention. FIG. 8 is a diagram showing the main structure of a sliding surface of a magnetic medium of a conventional magnetic head. In the figure, l is a track width regulating groove, 2, 2゛ is a ferrite block, 3, 3゜ is a sendust film, 4 is a bonding glass,
5 is a slider.

Claims (1)

[Claims] A magnetic head comprising a pair of core halves each having a magnetic thin film of high saturation magnetic flux density deposited on the end face of an oxide magnetic block, butted against each other with a magnetic gap material interposed therebetween. A magnetic head characterized in that the angle between the surface on which the magnetic thin film is deposited and the end surface of the head is set in the range of 50° to 80°.