JPS62173612A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obviate the generation of insulation breakdown during the production or use of a head by specifying the size of the spacings between a conductive coil and upper and lower magnetic materials where insulators occupy. CONSTITUTION:This head is constituted by using a baked photoresist or Al2O3 film or two layers; the Al2O3 film and baked photoresist, or SiO2 film or two layers; the SiO2 film and baked photoresist as the insulators 5, 7 between the magnetic materials 3, 8 and the conductive coil 6 and specifying the size of the spacings between the materials 3, 8 and the conductive coil 6 to >=1mum. The generation of the insulation breakdown during the production or use of the head is thereby obviated and the head having high reliability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thin film magnetic head, and particularly to a thin film magnetic head having excellent electrical insulation breakdown characteristics.

[Background of the invention]

Thin-film magnetic heads are inherently suitable for high-density recording, and are therefore widely used as recording/reproducing heads in magnetic disk drives. FIG. 2 is a sectional view of the tip of a conventional thin film magnetic head. In general, a thin film magnetic head consists of a substrate/slider material 1 made of ceramics or the like, an insulator 2 made of A12O3 or the like deposited thereon, and a lower magnetic material 3° insulating material. Gap material 4. Conductor coil 6 and its base insulator 5. and insulator 7 on the coil. Further, an upper magnetic body 8 is laminated to form a transducer section, and finally, it is sealed with a protective film 9 made of Al2O3 or the like.

In manufacturing and using such thin film magnetic heads, the electrical insulation of the coil is an important issue.

This may occur if the insulation performance of the thin-film magnetic head deteriorates due to changes over time, or if the insulation performance deteriorates due to breakdown or pseudo-destruction of the insulator due to electrostatic discharge.
If current leaks outside of the pre-set conductive paths within the thin-film magnetic head, sufficient recording and playback may not be possible, or leakage current may damage some parts of the head component or the recording medium facing the head. It is.

Deterioration in absolute performance due to changes over time can generally be prevented by using a highly reliable M-type body or by sealing the body with protective clothing.

To prevent static electricity discharge, take measures such as grounding workers during head manufacturing and limiting the materials used for head transportation and storage containers.
While the head is in use, countermeasures such as grounding the device casing are taken, but these are not sufficient.

When electrostatic discharge occurs in the thin film magnetic head, the conductive member exposed on the head surface, that is, the medium facing portion 11° of the magnetic bodies 3 and 8 in FIG. A high potential is applied to one of the output terminal pads, and the insulator 4 between the magnetic material 3°8 and the 4-piece coil 6
, 5.7, a discharge occurs to the other conductive member.

When a discharge occurs, one of the resistors 4, 5.7 undergoes "insulation breakdown" or "pseudo breakdown", and in the case of "insulation breakdown", the current capacity decreases due to the large current flowing during discharge. It was found that a small portion, ie, the medium facing portion 11 of the magnetic material, was burnt out. In addition, in the case of "pseudo-destruction" state,
After the discharge is repeated several times, a "dielectric breakdown" state occurs, resulting in a burnout state similar to the above. If such a phenomenon occurs during manufacturing, it can be detected through post-process inspection, but if inspection is omitted or the above phenomenon occurs during use, magnetic Not only will the head be damaged, but a discharge will occur between the magnetic body tip II of the head and the medium surface, and the medium will also be damaged.

As a method for improving such a problem, there is a method of forming another discharge path so that electrostatic charge discharge does not occur at the tip of the lower magnetic body 3 (see Japanese Patent Laid-Open No. 57-6431).

This is a method in which a discharge is caused between the conductive slider and the electrocardial discharge path so as not to damage the transducer section.

However, although this method is effective for conductive sliders (for example, see the slider described in Japanese Patent Application Laid-Open No. 55-163665), it is not effective for non-conductive sliders. In addition, even in the case of a conductive slider, when discharge occurs between the conductive slider and the discharge path, and the discharge is repeated, the electrical insulation performance between the slider and the discharge path deteriorates, and a conductive path is formed. Since recording current leaks to the slider side while the head is in use, sufficient current may not be supplied to the transducer section.

[Purpose of the invention]

The purpose of the present invention is to improve such conventional problems and to provide a thin film magnetic head that has excellent electrical insulation voltage characteristics, does not cause dielectric breakdown during head manufacture or use, and has high reliability. There is a particular thing.

[Summary of the invention]

"Yu,? L! In order to achieve the object, the thin film magnetic head of the present invention includes a lower magnetic material, a gap material, a conductor coil, and an upper magnetic material formed on a substrate, and an insulator between the conductive coil and the upper and lower magnetic materials. , fired photoresist film,
In a thin film magnetic head using a polyimide resin film, SiO2 film, A12031 model, or a combination thereof,
The present invention is characterized in that the size of the gap occupied by the insulator between the conductor coil and the upper and lower magnetic bodies is approximately 1 μm or more.

[Embodiments of the invention]

EMBODIMENT OF THE INVENTION Below, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a characteristic diagram of dielectric breakdown voltage of a thin film magnetic head showing an embodiment of the present invention, and FIGS.
FIG. 7 is a diagram showing analysis results of defective heads that were destroyed and non-defective heads that were not destroyed when an operation test was performed. Note that the numbers in Figures 3 and 4 are sample numbers, and for the heads of sample numbers 1 to 4 that were destroyed, the insulator dimensions were set to 41.
When added, the results are 0.3, 0.5, and 0°6.0, respectively.
．． It is shown that it was 7.

In Figure 4, for the head that did not cause dielectric breakdown, after the test, a voltage was applied between the magnetic material and the conductive coil by charging and discharging the capacitor, and the voltage at which the breakdown occurred, that is, the dielectric strength voltage, was investigated and the specifications This shows the dielectric strength voltage. That is, for the heads of Samples 1 to 5 that were not destroyed, the voltage when they were forcibly destroyed was 1.
05°1.20, 1.25, 1.20, 1.30, and the gap dimensions of the insulator at that time were 0.9, 1.0, 1°1, 1.1, 1.1. It has been shown that

The insulators of the test head were such that the insulator 7 between the upper magnetic body 8 and the conductor coil 6 was made of polyimide resin, and the lower magnetic body 3 was made of polyimide resin.
The insulator 5 between the conductor coil 6 and the conductor coil 6 is made of polyimide resin, and the gap material (insulator) 4 is made of polyimide resin.

It is alumina.

FIG. 1 shows the relationship between the dielectric breakdown voltage (normalized) due to the charging and discharging of the capacitor and the size of the gap occupied by the insulators 5 and 7 between the magnetic bodies 3 and 8 and the conductor coil 6. 1 in FIG. 1 is a head using the same polyimide resin as the test head in FIG. 4 above. 1st
From curve 2 (D) in the figure and the results of Figures 3 and 4,
The dimension of the gap corresponding to the standardized dielectric breakdown voltage of 1.0 becomes the critical point for dielectric breakdown to occur. In addition, the curve (2) shows the dielectric strength of the head using the insulators 5, 7 obtained by firing the first resist (between the magnetic materials 3, 8 and the conductor coil 6). Insulators 5 and 7 between conductor coils 6
The relationship between the gap size occupied by is shown.

In addition, the curve (■) indicates that the Al
When a 2O3 insulator is used, the curve ■ is a magnetic material 3,8
The case where an insulator of SiO2 film is used between the conductor coil 6 and the conductor coil 6 is shown.

The thin-film magnetic head of this embodiment has magnetic properties by setting the dimensions so that dielectric breakdown does not occur in the insulator between the conductor coil 6 and the magnetic body 3°8, regardless of whether the slider material is conductive or not. This prevents damage due to burnout of the tips of the bodies 3 and 8 and damage to the medium facing the head. From FIG. 3, it can be seen at what size of the insulator the dielectric breakdown occurs. Then, from Figure 1, by selecting the corresponding gap size so that the standardized dielectric breakdown voltage exceeds 1°0,
A thin film magnetic head without dielectric breakdown can be obtained.

Next, a suitable structure for the thin film magnetic head will be explained.

Experimental example 1: Insulator 5 between magnetic bodies 3 and 8 and conductor coil 6,
7, baked photoresist or A12
o3 film, or two layers of Al2O3 film and fired photoresist, or two layers of SiO2 film, or 5i02 film and fired photoresist, respectively, with magnetic materials 3 and 8.
and the conductor coil 6, and the head was constructed with a gap size of 1 μrn or more between the magnetic bodies 3, 8 and the conductor coil 6.

Experimental example 2: Polyimide resin or Al2O3 film,
Alternatively, two layers of polyimide resin and A12O3 film, or SiO2 film, or two layers of 5i02 film and polyimide resin are used as insulators between the magnetic material 3°8 and the conductor coil 6, and the gap size is 1 μm or more. The head was constructed as follows.

Note that the above-mentioned insulating film has variations in dielectric breakdown voltage due to pinholes, minute quadrielectric foreign matter in the film, etc., and for heads that require high reliability, it is necessary to By making the insulator dimension approximately 1.5 times larger than that of the above embodiment, a more reliable head was obtained.

In addition, in order to reduce pinholes, the insulator Foi-Res 1- and polyimide resin of the above example were applied in two or more times, and then patterned into a predetermined shape.

When the baked insulator was used in a thin-film magnetic head, it was possible to reduce variations in dielectric breakdown voltage.

Experimental example 3: Experimental example 1. In Experimental Example 2, the magnetic material was 3.8
The head was configured such that the gap occupied by the insulators 5 and 7 between the conductor coil 6 and the conductor coil 6 was approximately 1.5 μm or more.

Experimental example 4: Experimental example 1. In Experimental Example 2, the insulator was 5.7
Using an insulator obtained by applying photoresist used as
The head was configured to have a diameter of μm or more.

Experimental Example 5: In Experimental Example 4, the head was configured so that the insulator size between the magnetic bodies 3 and 8 and the conductor coil 6 was approximately 1.5 μm or more.

The above experimental example is the second example in explaining the thin film magnetic head.
As shown in the figure, it is assumed that the conductor coil 6 has one layer, but there are no restrictions whatsoever even if the conductor coil 6 has multiple layers.

As described above, in this embodiment, as the insulators 5 and 7 between the magnetic bodies 3 and 8 and the conductor coil 6, the head 1 made of polyimide resin, the head 1 made of 5102 film, and the head 1 made of Al2O
As shown in Figure 3, the gap dimensions occupied by the insulator are 0.3°, 0.5°, 0.6°, and 0.3° for the head (2) using three films and the head (excellent) using SiO2 film, respectively. When the value was set to 7, dielectric breakdown occurred, but as shown in Figure 4, no breakdown occurred when the values were set to 0.9, 1.0, 1.l, and 1.1, respectively. As shown, if the insulator dimension between the magnetic materials 3 and 8 and the conductor coil 6 is approximately 1.0 μm or more, dielectric breakdown will not occur, but considering the variation, 1.5 μm or more.
It is desirable to make it more than m.

〔Effect of the invention〕

As explained above, according to the present invention, the gap size occupied by the insulator between the magnetic material and the conductive coil is approximately l.

Since the thickness is set to 0 μm or more, dielectric breakdown does not occur during the manufacture and use of the head, making it possible to obtain a highly reliable head and improving the yield rate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the gap size occupied by an insulator and dielectric breakdown voltage according to an embodiment of the present invention, FIG. 2 is a sectional view of the tip of a thin film magnetic head to which the present invention is applied, and FIG. FIG. 4 is a diagram showing the results of an analysis of dielectric breakdown obtained through experiments using thin and thin heads. l varnish slider, 2: insulating layer, 3, 8: magnetic material, 4: gap material, 5, 7: insulator, 6: 4-body coil, 9: protective film, 10: medium facing surface, 11: magnetic material tip . Patent Applicant: Hitachi, Ltd. - “Representative Patent Attorney Masatoshi Isomura't,” Figure 1 Figure 2 Figure 3 Figure 3 Cow Diagram

Claims (1)

[Claims] (1) A lower magnetic body, a gap material, a conductor coil, and an upper magnetic body are formed on the substrate, and a fired photoresist film or a polyimide resin film is used as an insulator between the conductor coil and the upper and lower magnetic bodies. , a thin film magnetic head using a SiO_2 film, an Al_2O_3 film, or a combination thereof, characterized in that the dimension of the gap occupied by the insulator between the conductor coil and the upper and lower magnetic bodies is approximately 1 μm or more. Thin film magnetic head.