JPS59178609A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain a thin film magnetic head which can be used in a high frequency band of >=10MHz by providing notches in the end part of one magnetic pole pattern at least and allowing notches to face each other in parallel with the track breadthwise direction. CONSTITUTION:Notches are provided in the end part of one magnetic pole pattern, at least, of an upper magnetic pole 5 of a thin film magnetic head, and notches are allowed to face each other in parallel with the track breadthwise direction. This head is produced by changing a mask for magnetic pole pattern formation in the same process as a conventional head. When this head and an Fe2O3 recording medium are combined and the frequency dependence is measured at 40m/s relative speed, the frequency dependence is superior in high frequency characteristic as shown by a curve 20. It is guessed that the movement of a magnetic wall which is a cause of the degradation of the high frequency characteristic is prevented by notches. Consequently, the thin film magnetic head which can be used in the high frequency band of >=10MHz is obtained.

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 magnetic pole structure of a thin film magnetic head suitable for use in a high frequency band.

[Background technology]

Conventionally, bulk heads assembled by machining and winding have been used for magnetic heads, but the large stray capacitance and inductance of the windings have made it difficult to use in high frequency bands. In contrast, recently, thin-film magnetic heads manufactured using techniques similar to semiconductor manufacturing techniques, film formation using sputtering, thin film processing technology using photolithography, etc., have a high frequency band because they can reduce stray capacitance and inductance. It is thought that it can be used in, and is attracting attention. However, when we actually fabricated a thin film head, we found that in order to improve its high frequency characteristics, it was necessary to improve the high frequency characteristics of the magnetic thin film that forms the magnetic pole, and in general, it was not always possible to use it in a high frequency band. There is.

[Purpose of the invention]

An object of the present invention is to provide a thin film magnetic head that can be used in a high frequency band of approximately IOMH2 or higher.

[Summary of the invention]

In the present invention, the object is achieved by creating a notch at the end of the magnetic pole that corresponds approximately to the track width direction to prevent movement of the domain wall, which causes deterioration of the high frequency characteristics of the magnetic thin film.

[Embodiments of the invention]

FIG. 1(a) is a plan view of the upper magnetic pole portion of a conventional thin film magnetic head, and FIG. 1(b) is a sectional view corresponding to this portion. Symbol 1 is a non-magnetic substrate, 2 is a lower magnetic pole, 3 is a coil, 4
is an insulating layer, and 5 is an upper magnetic pole. The planar shape of the lower magnetic pole is approximately the same as the planar shape of the upper magnetic pole. In an actual head, there are lead wires for passing current through the coil, a protective film, etc., but these are omitted here and only the main parts are shown.

As shown in the example below, the shape of the magnetic pole is to make the width of the rear core that forms the magnetic path larger than the width (track width) at the magnetic pole tip A for recording and reproducing, thereby reducing magnetic resistance. Although this is common, various shapes have already been considered.

However, all of them had the characteristic that the ends of the magnetic pole patterns were smooth.

FIG. 2 shows a plan view of the upper magnetic pole portion of the thin film magnetic head according to the present invention. This cross section is the same as that of the conventional thin film magnetic head shown in Fig. 1, but there is a notch at the end of the magnetic pole pattern, and the notch exists almost parallel to the track width direction (T↓). Different from conventional heads. A head like this can be manufactured using the same process as the conventional method by changing the mask used when forming the magnetic pole pattern.

In this example, At203-Ti is used as the non-polar substrate.
Ni-19w fabricated by sputtering as C1 upper and lower magnetic poles
t%Fe alloy (approximately 2 μm thick), AA-4wt% Cu alloy (width 6 μm thickness 2
μm), At203 and PIQ (polyimide resin) were used as the insulating layer. After forming a desired thin film structure on the substrate, a magnetic pole tip A for final recording and reproduction was formed by machining such as cutting and polishing. The distance between the upper and lower magnetic poles at point A was approximately 0.6 μm, the maximum distance between the two magnetic poles was approximately 10 μm, and the rack width TW was approximately 30 μm. The depth of the notch and the width of its base were both about 1 μm.

FIG. 3 shows the frequency dependence of the recording and reproducing output when the head of this example and a p620!1 recording medium were combined and measured at a relative speed of 4 Qm/s. Curve 10 is the result for the conventional head shown in FIG. 1, and curve 20 is the result for the head of the present invention shown in FIG. 2. It can be seen that the present invention has better high frequency characteristics. The details of this reason are unknown, but it is because the state in which the magnetic poles are magnetized when current is passed through the coil is different between the two, and in the present invention, the domain wall is trapped in the notch and becomes difficult to move. Therefore, it is presumed that abnormal eddy current loss is reduced and high frequency characteristics are improved. This is most effective when the notch exists in the track width direction, that is, when the domain wall extends in the track width direction and is trapped at both ends.
The direction may be slightly off. The distance between the notches is preferably about 20 μm, but the optimum value varies depending on the thickness of the magnetic pole, the composition of the magnetic pole material 9, etc.

The inventive head also has another advantage of good reproducibility of reproduced waveforms.

Although it is desirable that both the upper and lower magnetic poles have notches, the effect is great even if at least one of the magnetic poles has a notch.

〔Effect of the invention〕

According to the present invention, a thin film magnetic head with good high frequency characteristics can be obtained (5) using the same manufacturing process as the conventional method.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of the magnetic pole part of a conventional thin film magnetic head, FIG. 1(b) is a cross-sectional view of the main part, and FIG. 2 is a plan view of the magnetic pole part of the thin film magnetic head of the present invention. FIG. 3 is a diagram showing the frequency characteristics of the thin film magnetic head of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Lower magnetic pole, 3... Coil conductor, 4... Insulating layer, 5... Upper magnetic pole, 1o... Frequency characteristics of conventional magnetic head, 20... Frequency characteristics of the magnetic head of the present invention. Agent Patent Attorney Akio Takahashi

Claims (1)

[Claims] 1. A thin film magnetic head characterized in that at least one magnetic pole pattern has a notch at the end thereof, and the notch exists substantially parallel to the track width direction.