JPS62222415A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To lower a coil resistance, and to reduce a head noise, by constituting a device so that the conductor pattern width at the rearward part of a spiral coil is reduced toward the inside direction, and the same widths are not provided over all of the turns. CONSTITUTION:On a substrate 10, an upper and a lower magnetic poles 11 and 15, a gap layer 12, a coil 13 and an insulator 14 are formed, and coil conductor pattern widths L at the C part of the rearward part are set as L1=12mu for three turns of the inside, L2=16mu for the next two turns, L3=20mu for the next two turns, and L4=24mu for one turn of an outside, and the pattern width of a B part in a magnetic path is set as a constant 6mu. Thus, since the pattern width at the rearward part is reduced toward the inside, and the coil resistance is reduced, the head noise can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head, and particularly to a thin film magnetic head that is suitable for high density recording, has low noise, and has a large projection.

[Conventional technology]

Conventional thin film heads usually have a spiral coil as shown in Japanese Patent Application Laid-Open No. 55-84020, and the pattern width of the coil conductor is different in the magnetic path, on the sides, and at the rear. The pattern width of the same part in each turn is the same. That is, as is clear from FIG. 3 showing the AA' cross section in the magnetic path in FIG. 2, the conductors have the same pattern width L1° in the B section and the rear C section of the magnetic path, regardless of the turn. It can be seen that it has L2. The same applies to the side edges. Another example is JP-A-55-6
As shown in Japanese Patent No. 2523, there is a thin film magnetism in which the pattern width of the conductor in the magnetic path is such that the cross-sectional area of the conductor located at a distance from the recording medium facing surface A is larger than the cross-sectional area of the conductor located at a closer distance. The head is exposed. That is, an example is shown in which the pattern width decreases toward the inside of the coil in the magnetic path. This has been shown as a method for effectively generating a head magnetic field with a smaller recording current in view of the relationship between the drive current and the generated magnetic field.

However, sufficient consideration has not been made from the viewpoint of coil resistance.

Thin film magnetic heads are used with the current density of the coil conductor usually being about 5.times.10.sup.5 A/ad or less, which is sufficient for the permissible current density of the conductor, although it depends on the purpose of use.

On the other hand, due to the demand for higher recording densities, there is an urgent need to reduce head noise, that is, to reduce the coil resistance of the head, so it is generally better to reduce the coil resistance than to reduce the current density used. considered desirable.

The area in which a coil conductor can be formed is limited by the requirements for the flying characteristics of the head, so the coil conductor of a thin film magnetic head must be formed within a limited area so as to have as little resistance as possible.

[Problem that the invention seeks to solve]

As described above, the conventional technology does not take coil resistance into consideration, and has the problem of large head noise. An object of the present invention is to lower coil resistance and reduce head noise. (Means for Solving the Problem) The above object is to change the pattern width at the rear of the conductor coil toward the inside of the coil, that is, at the rear contact portion of both the upper and lower magnetic poles 2 and 2' (section E in Figs. 2 and 3). ).

More specifically, the pattern at the rear of the coil is divided into several parts, and a conductor having a pattern width of Ll [μm] is wound in n1 turns each. At this time, the pattern width always increases from the inside of the coil to the outside, and nl is n t
The wire is wound in a range that satisfies L i < 40, and Σn s
= N (N: total number of windings), the above objective can be achieved.

[Effect]

The resistance of the coil conductor can be reduced by shortening the length of the portion where the conductor has a small cross-sectional area and increasing the length of the portion where the conductor has a large cross-sectional area. However, if you simply increase the pattern width,
Since the length of one circumference of the outer periphery of the coil becomes longer, the resistance does not necessarily become smaller.

On the other hand, if an attempt is made to reduce the circumferential length by reducing the outer edge of the coil, the pattern width must be reduced, which may result in a smaller cross-sectional area and an increase in resistance. The overall coil resistance can be lowered by making the inner pattern width smaller so that the length of the inner circumference of the coil becomes shorter, and increasing the pattern width of the outer part where the length of the outer circumference becomes longer. .

Also, from the point of view of recording and reproducing efficiency, it is desirable to keep the magnetic path as short as possible, so it is desirable to make the pattern width of the coil formed in the magnetic path as small as the current density allows.The width of the coil pattern is determined by the levitation characteristics. Relationships cannot grow beyond a certain point. Therefore, it is desirable to reduce the resistance by adjusting the pattern width at the rear of the coil.

〔Example〕

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

FIG. 1 is a sectional view of a thin film head of the present invention (A in FIG. 2).
-A' is a diagram showing a cross section corresponding to the cross section). Substrate 10
on top of the lower magnetic pole 11. Gap layer 12, coil 13. Insulator 14. An upper magnetic pole 15 is formed. The pattern width of the rear (C part) coil conductor is Lx = 12 μm for the inner n1 = 3 tangs, and Lz = 12 μm for the next n2 = 2 tangs.
16 μm, the next n3 = 2 tans is La = 20 pm, the outermost n4 = 1 tan is L + =: 24 μm, total nt.
+nt+na+n4=8 turns of winding.

Note that the spacing between patterns is approximately 4 μm everywhere.

The pattern width in the magnetic path (part B) other than the rear part is constant at 6 μm for each turn, the pattern interval is constant at 3 μm, and the side part (
The pattern width of the portion (corresponding to portion D in FIG. 2) is constant at 10 μm for each turn, and the pattern interval is constant at 4 μm regardless of the turn.

The conductor height is 2 μm, and the conductor material is copper. The conductor pattern was formed by sputtering and etching by ion milling, and the taper angle of the conductor was approximately 60'.

The DC resistance of this coil conductor was 4.3Ω.

Similarly, the coil resistance of a prototype head made with the rear coil pattern width constant at 12 μm was 6.2Ω.

The coil resistance of the prototype head with a constant 24 μm was 5.
In both cases, only a resistance value of 9Ω, higher than that of the present invention, was obtained.

As shown in this example, if the coil conductor is formed into an ellipse so that the conductor pattern width at the rear of the coil becomes smaller toward the inside, a coil with low resistance can be obtained.Various combinations of pattern width and number of turns As a result of making a prototype head, we found that a conductor having a pattern width L1 (μm) at the rear of the coil was wound every n1 turn, and at this time, the wire was wound so that ntLt (40) was satisfied, and the total number of turns N = Σn1. It was found that the resistance value can be effectively reduced by doing so.

〔Effect of the invention〕

According to the present invention, since a coil conductor with low resistance can be obtained, there is an effect of reducing noise.

Further, in the embodiments, a case has been described in which the coil conductor is formed in one layer in a spiral shape, but it goes without saying that the present invention is also applicable to a case in which the coil conductor is formed in two or more layers. In the case of a multilayer coil, the present invention may be satisfied for each layer.

In some cases, the coil conductor may be formed by changing the pattern width of the coil conductor inside the magnetic path or on the side, but in order to reduce the coil resistance, it is best to adjust the width of the conductor pattern at the rear of the coil. Therefore, it is natural that the present invention can be applied to combinations of these.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a thin film head according to an embodiment of the present invention;
FIG. 2 is a plan view of a general thin film head. FIG. 3 is a sectional view taken along the line AA'. DESCRIPTION OF SYMBOLS 1... Conductor coil, 2, 2'... Magnetic pole, 3... Lead wire, 10... Board, 11... Lower magnetic pole, 12
...Gap layer, 13...Conductor coil, 14...
Insulator, 15... Act f mouth 2nd mouth! ...Conductor coil 2... - Bond 3...G1 each outlet

Claims (1)

[Claims] 1. A thin film magnetic head characterized in that the width of the conductor pattern at the rear of the spiral coil is the same or increases from the inside to the outside for each turn, and is not the same over all turns.