JP2002170210A - Magnetoresistive magnetic head, and electromagnetic transduction characteristic measurement method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield form and a measuring method capable of increasing measuring accuracy. SOLUTION: The shapes of shields 1 and 2 are designed such that the direction of a magnetic field effectively applied on a magneto-resistance effect element 3 is perpendicular to a medium opposite surface 4. Alternatively, a problem is solved by carrying out measuring with the angle θ of an applied magnetic field inclined such that the direction of a magnetic field effectively applied on the magneto-resistance effect element 3 is perpendicular to the medium opposite surface 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield type magnetoresistive head, and more particularly to a magnetic head characterized in that a read head shield is separated from a write head. The present invention relates to a shield shape, a measuring method, and a measuring device capable of efficiently and highly accurately measuring an electromagnetic conversion characteristic of a resistance effect element.

[0002]

2. Description of the Related Art As a method for measuring the electromagnetic conversion characteristics of a magnetoresistive head, an external magnetic field is applied from a direction parallel to the surface of the magnetoresistive element of the head as shown in Japanese Patent Application Laid-Open No. 2000-163722. In general, a method using measurement as a measuring means is known. This measurement method is an excellent inspection means that can be applied to all production lines using a magnetoresistive element because it is not necessary to float the magnetic head above the recording medium. Therefore, in the production line of the magnetic head, using this principle, the quality of the electromagnetic conversion characteristics of the magnetic head is determined based on the magnitude of the reproduction output corresponding to the magnitude of the magnetic field applied from the outside.

In response to the recent increase in recording density of a magnetic recording / reproducing apparatus, the sensitivity of a reproducing head has been required to be higher, and a highly accurate measurement of an output voltage has been required. As a result of recent research by the present inventors, it has become clear that the direction of a magnetic field applied from the outside does not always match the direction of a magnetic field actually entering the magnetoresistive element. Further, the cause is caused by the shape of the shield, and is largely caused by a difference in the length of the two shields sandwiching the magnetoresistive element.

[0004] The shield shape of the magnetoresistive head is designed so that the lower shield formed first is longer and the upper shield formed later is shorter than the lower shield because of a manufacturing process employing a lamination process. Are known. Also, in the case of a recording / reproducing type magnetic head, there is also known a type in which the lower shield is shorter than the upper shield in order to reduce the influence of the magnetic field generated by energizing the recording head coil on the lower shield. . These are the shield shapes from the viewpoint of the manufacturing process or from the viewpoint of the relationship between the recording head and the reproducing head, and the description of the shield shape from the viewpoint of measuring and evaluating the electromagnetic conversion characteristics of the magnetoresistive head. Has not been.

Further, in order to improve the measurement accuracy by a measuring method as disclosed in Japanese Patent Application Laid-Open No. 2000-163722, it is necessary to use not a direction of an external magnetic field applied to a magnetic head but an effective magnetoresistive element. It is necessary to consider the direction of the magnetic field acting on the
Does not describe the effective applied magnetic field direction accompanying the shape of the shield

[0006]

In measuring the electromagnetic conversion characteristics of the magnetoresistive head, one of the upper and lower shields is longer and the other is shorter in the conventional structure head as described above. Because of the asymmetry, the direction of the magnetic field that effectively acts on the magnetoresistive effect element is inclined in the direction of the relative movement between the medium and the head, and therefore differs from the direction of the magnetic field that enters the head from the medium in actual use. The conditions of the input magnetic field do not match in measuring the characteristics as As a result, the reproduction output from the actual device cannot be correlated with the reproduction output due to the application of an external magnetic field, resulting in a decrease in accuracy in the head inspection process. That is, the measurement accuracy is reduced by the shape of the shield, and accurate measurement and sorting cannot be performed.

An object of the present invention is to provide a shield shape and a measuring method which solve the above problems and improve the measuring accuracy.

[0008]

The above-mentioned problem of the reduction in measurement accuracy is solved by designing the shield shape such that the direction of the effective magnetic field entering the magnetoresistive element is perpendicular to the medium facing surface. You.

When the shield shape cannot be changed from the conventional type due to a manufacturing process or other reasons, the applied magnetic field angle is set so that the direction of the magnetic field effectively acting on the magnetoresistive element becomes perpendicular to the medium facing surface. It is solved by tilting and measuring.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a magneto-resistance effect type magnetic head which best illustrates the features of the present invention. A general measurement for measuring the electromagnetic conversion characteristics of the magnetoresistive element 3 by applying an external magnetic field 5 to the magnetoresistive element 3 sandwiched between the shields 1 and 2 from a direction perpendicular to the medium facing surface 4. The method is shown.

In this case, the length of the longer shield is h
1. When the length of the shorter shield is h2, h2 / h
Assuming that 1 is 0.8 to 1.0, the angle θ between the direction perpendicular to the medium facing surface and the direction of the magnetic field in the magnetoresistive element 3 becomes 1 ° or less as shown in FIG. It is almost the same as the direction of the magnetic field that enters from the medium during actual use.

When h2 / h1 must be set to 0.8 or less for the manufacturing process and other reasons, the angle θ is shown in FIG. 2 when a magnetic field is applied from a direction perpendicular to the medium facing surface. Even if such a shield is used, the angle θ can be made substantially zero by inclining the applied angle of the external magnetic field 5 in the direction of relative movement between the medium and the head as shown in FIG. it can.

FIG. 4 shows the applied magnetic field tilt angle φ required to make the angle θ zero when h2 / h1 is changed. It is necessary to incline the applied magnetic field as h2 / h1 approaches zero. For example, when h2 / h1 = 0.5, φ = 10 °
If it is inclined, the angle θ between the direction perpendicular to the medium facing surface and the direction of the magnetic field in the magnetoresistive element 3 is 0.

FIG. 5 schematically shows the function of an electromagnetic conversion characteristic measuring device of a magnetoresistive effect type magnetic head having a function of inclining a magnetic field applied to the magnetic head. Magnetoresistive magnetic head 1
Equipment 11 and 12 for applying a magnetic field such as a permanent magnet or an electromagnet so as to sandwich 0 are provided. Two facilities for applying a magnetic field are not necessarily required, and a magnetic field may be applied to only one of 11 or 12, as shown in FIG. A method using a mold core or the like to sandwich the magnetic head in the gap, or a leakage magnetic field from the gap using them may be used. The magnetic field applied to the head from the equipment for applying the magnetic field may be either a static magnetic field or a dynamic magnetic field, and may be any type of magnetic field such as a pulse wave, a sine wave, and a triangular wave.

This measuring apparatus is a magnetoresistive head 1
The physical relative position with respect to the magnetic head 10 is changed, for example, by rotating either the magnetic field applying equipment or the magnetic head as shown in FIG. 5 or sliding as shown in FIG. By having a function of causing the magnetic head 10, the direction of the magnetic field applied to the magnetic head 10 can be inclined in a direction in which the magnetic head 10 makes a relative motion with the medium.

It is apparent that the present measuring method can be used for inspection of all manufacturing processes using a magnetoresistive element such as a wafer, a slider, a head assembly, a head stack assembly, a servo track writer, and a disk drive.

Further, the function of confirming the direction and strength of the magnetic field in the equipment may be always performed by using a magnetic sensor such as a Hall element or a magnetoresistive element.

[0019]

According to the present invention, when the electromagnetic conversion characteristics of a magnetoresistive element are measured by applying an external magnetic field, the direction of the magnetic field that effectively acts on the magnetoresistive element can be determined in actual use, that is, in a disk. Since the direction of the signal magnetic field received from the recording medium can be made substantially the same as when mounted on a drive or the like, the electromagnetic conversion characteristics can be measured accurately and accurately.

According to the present invention, when the solution is solved by the shield shape of the magnetic head, the conventional electromagnetic conversion characteristic measuring instrument can be applied to a development machine or a production line without any change, so that a large capital investment is required. The need is avoided.

If the shield shape cannot be changed from the viewpoint of process or design, it can be applied to a development machine or a production line by using an electromagnetic conversion characteristic measuring device having a function of changing the direction of magnetic field application. A product measured with high accuracy can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a shielded magnetoresistive head when a magnetic field is applied from a direction perpendicular to a medium facing surface.

FIG. 2 is a diagram illustrating a magnetic field angle θ that effectively acts on a magnetoresistive element when a shield length is changed in the state of FIG. 1;

FIG. 3 is a cross-sectional view of a shielded magnetoresistive magnetic head when an applied magnetic field is inclined in a direction of relative movement between the medium and the head.

4 is a diagram showing an applied magnetic field tilt angle φ at which a magnetic field angle θ that effectively acts on a magnetoresistive element in the state of FIG. 3 becomes zero.

FIG. 5 is a diagram illustrating a first example of a schematic function of an electromagnetic conversion characteristic measuring device having a magnetic field application angle changing function.

FIG. 6 is a diagram illustrating a second example of a schematic function of an electromagnetic conversion characteristic measuring device having a function of changing a magnetic field application angle.

FIG. 7 is a diagram showing a third example of the function of an electromagnetic conversion characteristic measuring device having a magnetic field application angle changing function.

[Description of Signs] 1: Shield 1, 2: Shield 2, 3: Magnetoresistance effect element, 4: Media facing surface, 5: Externally applied magnetic field, h1: Length of shield 1, h2: Length of shield 2, θ: the angle between the direction perpendicular to the medium facing surface and the direction of the magnetic field at the tip of the magnetoresistive element, φ: the angle between the direction perpendicular to the medium facing surface and the direction of the externally applied magnetic field, 10: magnetic Resistance effect type magnetic head, 11: magnetic field applying equipment 1, 12: magnetic field applying equipment 2,

Claims (5)

[Claims] 1. A magnetic body for a first shield, a magnetoresistive element, and a magnetic body for a second shield are arranged along a direction perpendicular to the medium facing surface, and are perpendicular to the medium facing surface. A magnetoresistive effect type magnetic head in which the direction of the magnetic field at the magnetoresistive element portion is substantially the same as the direction of the externally applied magnetic field when a magnetic field is externally applied in the following direction. 2. A magnetoresistive magnetic head in which a first shield magnetic body, a magnetoresistive element, and a second shield magnetic body are arranged along a direction perpendicular to the medium facing surface. 2. The magnetic device according to claim 1, wherein a length ratio of the first shield magnetic body to the second shield magnetic body is 0.8 to 1.0. Resistance effect type magnetic head. 3. A magnetoresistive magnetic head in which a first shield magnetic body, a magnetoresistive element, and a second shield magnetic body are arranged along a direction perpendicular to the medium facing surface. In a magnetoresistive head having a first shield magnetic body and a second shield magnetic body having different lengths, the direction of the magnetic field in the magnetoresistive element portion is different from the medium facing surface. A method for measuring electromagnetic conversion characteristics of a magnetoresistive element, wherein an externally applied magnetic field is inclined in a direction of relative movement between a medium and a head so that the magnetic field becomes substantially a right angle. 4. The direction of a magnetic field in a magnetoresistive element is
A method for measuring electromagnetic conversion characteristics of a magnetoresistive element, wherein an externally applied magnetic field is tilted in a direction of relative movement between a medium and a head so that the direction of an input magnetic field when actually used is substantially the same. 5. An apparatus for measuring electromagnetic conversion characteristics of a magneto-resistance effect type magnetic head having a function according to claim 3.