JPH0536028A - Thin-film magnetic head - Google Patents

Abstract

PURPOSE:To lower the resistance of a thin-film coil and to decrease head noises by optimizing the shape over the entire part of the coil. CONSTITUTION:The thin-film coil 1 is formed so such a shape that the ratio Xa/Ya of the coil width Xa in a track width direction and the coil width Ya in a gap depth direction is between 0.5 and 1.0. The coil is formed to such a shape that the ratio Yb/Yc between the coil width Yb and Yc in the gap depth direction is between 0.4 to 0.7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head used in a magnetic recording / reproducing apparatus, and more particularly to reducing the resistance of a thin film coil.

[0002]

2. Description of the Related Art A coil formed of a thin film has a smaller cross-sectional area than a coil formed by winding a wire used in a conventional bulk type head, so that it generally has a high resistance value and causes noise. Has become.

The method of lowering the resistance of the coil can be divided into a method requiring a change in the process technology and a method not requiring a change in the process technology from the viewpoint of the manufacturing process. The former is a method of increasing the coil cross-sectional area by increasing the coil film thickness and increasing the coil width by reducing the space between the coils. The latter is an optimization of the coil plane shape that can be handled only by changing the photomask. .

The present invention realizes the reduction of the resistance of the coil by the latter method which can be dealt with by the conventional process technology.
As another example in which the latter method is used to reduce the resistance, Japanese Patent Application Laid-Open No. HEI-1
There is a method disclosed in Japanese Patent Publication No. 223612. Since the coil length per one turn becomes longer as the coil becomes closer to the outer circumference, the coil resistance increases as the coil width at each circumference becomes the same at the outer circumference.Therefore, the coil width is made larger at the outer circumference and the resistance value of each circumference is averaged. It was to reduce the overall resistance value.

[0005]

By the way, the above conventional example is an invention relating to optimization of the coil width of each circumference of the thin film coil, and the overall shape of the coil, that is, the shape of the outermost circumference and the innermost circumference of the coil is taken into consideration. There wasn't. In reality, the overall shape of the coil is limited by the head performance and the shape of the head. As an example, a thin film magnetic head for a magnetic disk device is shown in FIG. In this case, the overall shape of the coil is limited in two places. One is the distance between the front gap and the rear gap, which is determined in relation to the size of the magnetic circuit, that is, the head efficiency. The other is the distance between the outermost coils in the track width direction, which is limited by the width of the slider. On the other hand, in other portions, for example, in the gap depth direction, the coil shape can be relatively freely set on the rear side of the back gap (the side opposite to the front gap).

In order to reduce the resistance of the coil, it is necessary to optimize not only the width of each circumference of the coil but also the overall shape of the coil in consideration of the balance between the restricted portion and the unrestricted portion.

An object of the present invention is to provide an optimum overall coil shape and reduce coil resistance.

[0008]

In order to achieve the above object, the present invention defines the shape of a thin-film coil as the outermost circumference in the track width direction of the coil, the maximum value of the distance between the coils being Xa, and the outermost circumference in the gap depth direction. When the maximum value of the distance between the coils is Ya, the shape is such that the following relationship holds.

[0009]

## EQU00003 ## 0.5 ≦ Xa / Ya ≦ 1.0
(1) In the distance between the outermost coil and the innermost coil in the gap depth direction, the maximum value on the front gap side of the back gap is Yb, and the maximum value on the side opposite to the front gap is Yc. The shape is such that

[0010]

## EQU4 ## 0.4 ≦ Yb / Yc ≦ 0.7
… (2)

[0011]

As described above, the overall shape of the coil is limited by the head performance and the shape of the head. As an example, when the thin film magnetic head for the magnetic disk device shown in FIG. 1 is taken, there are two restrictions, namely, the distance between the front gap and the rear gap and the distance between the outermost peripheral coils in the track width direction. On the other hand, in other portions, for example, in the gap depth direction, the coil shape can be relatively freely set on the rear side of the back gap (the side opposite to the front gap).

However, the head performance and the shape of the head are not limited, and the shape of the portion in which the coil shape can be freely set must be determined in balance with the other limited portions. For example, in FIG. 1, if the coil width on the rear side of the back gap is increased, the coil resistance of that portion is reduced, but the coil length of the portion connected to that portion is increased and the resistance is increased. However, it is not always advantageous for lowering the resistance.

According to the present invention, the ratio of the distance between the outermost peripheral coils in the track width direction of the coil to the distance between the outermost peripheral coils in the gap depth direction and the distance between the outermost peripheral coil and the innermost peripheral coil in the gap depth direction are used. The overall shape of the coil is optimized by defining the ratio of the distance between the front gap side and the opposite side of the back gap, whereby the coil resistance is reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a plan view of the thin film head of the present invention. In the thin film head, a lower magnetic layer is formed on a non-magnetic substrate, an insulating film and a thin film coil are laminated, and then an upper magnetic layer is formed to complete the wafer process. The upper and lower magnetic layers are connected by two contact holes formed in the insulating film, and these two contact holes form a gap. One of the gaps that contacts the recording medium is called a front gap, and the other is called a back gap. In FIG. 1, components other than the gap and the coil are omitted. The thin film coil is spirally formed on the same plane around the back gap, and is formed by laminating a single layer or a plurality of layers. However, in FIG. 1, only the thin film coil 1, the front gap 4, and the back gap 3 are shown, and other magnetic cores and the like are omitted.

The overall shape of the thin film coil is regulated by various restrictions. For example, in the case of the thin film head for a magnetic disk shown in FIG. 1, there are two parts that restrict the overall shape of the coil. One is the distance between the front gap and the rear gap. Since the magnetic path length is almost twice this interval, if the interval is too wide, the magnetic circuit becomes large and the head performance deteriorates. Therefore, restrictions are required. this is,
This is a limitation common not only to a thin film head for a magnetic disk but also to a head having a thin film coil of this type. Further, a limitation peculiar to a thin film head for a magnetic disk is a width of a slider to which the head is attached. The head must be processed so as not to exceed the width of the slider, and the coil must be formed further inside thereof so as not to be cut by the head processing.

As shown in FIG. 1, the maximum distance between the outermost coils in the track width direction of the coil is Xa, and the maximum distance between the outermost coils in the gap depth direction is Ya. FIG. 2 shows the relationship between the ratio Xa / Ya and the coil resistance R at this time. The coil resistance R is minimum when Xa / Ya is 0.6. However, the value of Xa / Ya when the coil resistance R becomes the minimum changes somewhat depending on conditions such as the number of coil turns, the coil film thickness, and the magnetic path length. For example, the number of coil turns is 15 turns, the coil film thickness is 3 μm, and the magnetic path length is 400.
The coil resistance R when μm is minimum when the value of Xa / Ya is 0.6, and the coil resistance R at that time is 4.9Ω. Similarly, X for 20 turns, 5 μm, and 300 μm
The value of a / Ya is 0.9 and the coil resistance R is 8.8Ω. Taking the above into consideration, when the optimum value of the coil resistance R is set up to 10% of the minimum value of the coil resistance R in FIG. 2, the value of Xa / Ya at that time is given by the expression (1).

Therefore, if the coil shape is such that Xa / Ya is in the above range, the coil resistance R can be obtained within the range of up to 10% of the minimum value even if conditions such as the number of coil turns are changed. Recognize.

Another embodiment of the present invention will be described with reference to FIGS. 1 and 3.

The head structure is similar to that of the above embodiment. As shown in Fig. 1, the distance between the outermost coil and the innermost coil in the gap depth direction of the coil is Yb, the maximum value of the front gap side portion of the back gap, and the maximum value of the portion opposite to the front gap. Be Yc.

FIG. 3 shows the relationship between the ratio Yb / Yc and the coil resistance R in this case. The coil resistance R is minimum when Yb / Yc is 0.5. But as above
The value of Yb / Yc that minimizes the coil resistance R changes somewhat depending on conditions such as the magnetic path length. For example, the number of coil turns is 15
The coil resistance R when the turn, the coil film thickness is 3 μm, and the magnetic path length is 400 μm is minimum when the value of Yb / Yc is 0.5, and the coil resistance R at that time is 4.4Ω. Similarly 2
In the case of 0 turns, 5 μm and 300 μm, the value of Yb / Yc is 0.6 and the coil resistance R is 8.8Ω. Taking the above into consideration, assuming that the minimum value of the coil resistance R up to 10% is set as the optimum range of the coil resistance R in FIG. 2, Yb /
The value of Yc is given by equation (2).

Therefore, if the coil shape is such that Yb / Yc is in the above range, the coil resistance R can obtain a value within a range up to 10% even if conditions such as the magnetic path length are changed. I understand.

[0023]

According to the present invention, the overall shape of the coil can be optimized and the coil resistance can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of a thin film magnetic head showing first and second embodiments of the present invention,

FIG. 2 is an explanatory view showing the effect of the first embodiment showing the relationship between the coil resistance in the track width direction and the gap depth direction of the coil forming region and the coil resistance;

FIG. 3 is an explanatory diagram showing the effect of the second embodiment showing the relationship between the coil resistance and the ratio of the dimension from the back gap to the front gap in the coil forming region and the dimension after the back gap.

[Explanation of symbols]

1 ... Thin film coil, 2 ... slider, 3 ... back gap, 4 ... Front gap.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeo Aoki             1410 Inada, Katsuta City, Ibaraki Japan             Tachi Works Tokai Factory

Claims (2)

[Claims] 1. A lower magnetic core, an insulating film, a thin film coil spirally wound a plurality of times on the same plane, an upper magnetic core, etc. are laminated on a substrate, and the lower magnetic core and the upper portion are formed in a back gap. In a thin film magnetic head in which the magnetic cores are magnetically connected, and the lower magnetic core and the upper magnetic core face each other across the non-magnetic thin film in the front gap, the distance between the outermost coils of the thin film coil in the track width direction. Is a maximum value of Xa, and a maximum value of the distance between the outermost circumferential coils in the gap depth direction is Ya, the following relationship is established. ## EQU1 ## 0.5 ≦ Xa / Ya ≦ 1.0
… (1) 2. A lower magnetic core, an insulating film, a thin-film coil spirally wound a plurality of times on the same plane, an upper magnetic core, etc. are laminated on a substrate, and the lower magnetic core and the upper portion are formed in a back gap. In a thin film magnetic head in which the magnetic cores are magnetically connected, and the lower magnetic core and the upper magnetic core face each other across the non-magnetic thin film in the front gap, the outermost coil in the gap depth direction of the thin film coil A thin film magnetic head characterized in that the following expression is established, where Yb is a maximum value of a portion on the front gap side with respect to the back gap and Yc is a maximum value of a portion on the side opposite to the front gap in the distance between the inner circumference coils. ## EQU2 ## 0.4 ≦ Yb / Yc ≦ 0.7
… (2)