JPH01259584A - Magnetoresistive element - Google Patents

Abstract

PURPOSE:To enable a biased magnetic field strength to be arbitrarily set and allow mass production by forming a magnetoresistive element made of a ferromagnetic metal thin film on top of a substrate and a conductive thin film with a predetermined pattern on bottom of the substrate and by obtaining a magnetic field for magnetic biasing by the conduction of the conductive thin film. CONSTITUTION:An Ni-Fe film 12, a magnetoresistive element 12a, power supply terminals 12b, 12d, and a signal output terminal 12c are arranged on a ceramic substrate 11. On the bottom of the substrate 11, a conductive pattern 13 formed of a Cu thin film is arranged in a direction forming an angle of about 45 deg. with respect to the direction of forming the magnetoresistive element 12a. When the conductive thin film is conducted, a magnetic field is generated and a magnetically biased voltage is applied to the magnetoresistive element. Accordingly, the level of the magnetic biasing can arbitrarily adjusted by controlling the current supplied to the conductive thin film, thereby simplifying the formation of and allowing the mass-production for the element.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a magnetoresistive element used as a magnetic detection sensor, mainly when detecting the rotational speed of a rotating body such as a motor.

(b) Conventional technology FIG. 3 is an explanatory diagram showing the operation of a magnetoresistive element. When a signal magnetic field Os ig acts on a thin film 1 having a magnetoresistive effect in an orthogonal direction, the thin film! The direction of the magnetization Xt inside is at an angle θ
As a result, the electrical resistance of terminals 2° and 3rd open generally decreases by 2 to 5%. Therefore, the resistance change between the terminals 2.3 with respect to the magnetic field Hs ig applied to the magnetoresistive element has a hysteresis characteristic as shown in FIG. 4. This hysteresis characteristic can be suppressed by applying a bias magnetic field Hbias, so in a conventional magnetoresistive element, a magnetoresistive element 5 made of a ferromagnetic material is placed on a substrate 4 as shown in FIG. Terminals 6, 7, and 8 are formed on the substrate 4, and a bias permanent magnet 9 is attached to the back surface of the substrate 4.

(c) Problems to be Solved by the Invention However, in such a conventional magnetoresistive element, since a bias magnetic field must be applied to the magnetoresistive element 5 in a fixed direction, the bias permanent magnet 9 It is necessary to affix it to the substrate 5 with high precision. By the way, the bias magnetic field strength between elements varies not only due to the accuracy of mounting the bias permanent magnet 9 to the substrate 4 but also due to the magnetic force of the bias permanent magnet 9. The problem was that it was difficult to mass produce.

This invention was made in consideration of these circumstances,
The object of the present invention is to provide a magnetoresistive element that can apply a bias using a magnetic field generated by a current and arbitrarily set the bias magnetic field strength.

(d) Means for Solving the Problems This invention consists of a substrate, a magnetoresistive element made of a ferromagnetic metal thin film formed on the surface of the substrate, and a conductive thin film formed on the back surface of the substrate and having a predetermined pattern. , a magnetoresistive element characterized by forming a magnetic field for magnetic bias to a magnetoresistive element by applying current to a conductor thin film.

Ceramic is mainly used for the substrate, and Ni-Pa, N1-Go, etc. are used for the ferromagnetic metal thin film. Further, it is preferable that the conductive thin film is formed at an angle perpendicular to or at an angle of 45° to the current direction of the magnetoresistive emerent.

(e) Working conductor When current is passed through the thin film, a magnetic field is generated and a magnetic bias is applied to the magnetoresistive element. Therefore, the degree of magnetic bias can be adjusted arbitrarily by controlling the magnitude of the current flowing through the conductive thin film, so when manufacturing the magnetoresistive element, the magnetoresistive element and the conductive thin film are attached to the substrate. There is no need for high precision in positional relationships.

(f) Examples The present invention will now be described in detail based on examples shown in the drawings. This invention is not limited by this.

FIG. 1 is a top view showing an embodiment of the present invention, and FIG. 2 is a bottom view of FIG. 1. In these figures, 2 indicates a thickness of 0.
6IIM ceramic substrate, 12 is 0 thickness formed by resistance heating, electron beam or sputtering method.
．． 05-0.1 μmf) Ni-Fe film. 1
2a is a magnetoresistive element, +2b and +2d are power supply terminals, and 12c is a signal output terminal. Board 11
As shown in FIG. 2, a conductive pattern 13 is formed on the back surface of the magneto-resistance effect element 12 at an angle of approximately 45° to the direction in which the magnetoresistive element 12 is formed. Conductor pattern! 3 has a thickness of 100 μm formed by plating or printing method 17) cu
It is a thin film. In addition, through holes 14 and 15 are formed at two corners of the board 11, and terminals are formed at the two corners of the board 11. 2b and the terminal 13a, and the terminal 12d and the terminal 13b are electrically connected.

In such a configuration, when a voltage is applied to the terminals 12b and 12d, a current flows through the magnetoresistive element section 12a, and the conductor pattern on the back surface! Current also flows through 3. Since the resistance of the conductor pattern 13 is set to about 1/10 of the resistance of the magnetoresistive element section 12a, a large current flows through the conductor pattern 13. A magnetic field is generated by the current flowing through the conductor pattern 13, and the magnetic field applies a magnetic bias to the magnetoresistive element section 12a. Therefore, when the magnetoresistive element configured in this manner is used as a magnetic sensor, it is possible to sufficiently suppress its hysteresis characteristics.

(g) Effects of the invention According to this invention, it is possible to apply a magnetic bias to the magnetoresistive element by forming a conductive film on the back surface of the substrate on which the magnetoresistive element is formed and passing a current through the conductor. becomes.

Therefore, there is no need for high positional accuracy in manufacturing, simplifying the manufacturing of the magnetoresistive element, and improving mass productivity.

[Brief explanation of the drawing]

Fig. 1 is a top view showing an embodiment of the present invention, Fig. 2 is a bottom view of Fig. 1, Fig. 3 is an explanatory diagram showing the operating principle of the magnetoresistive element, and Fig. 4 is shown in Fig. 3. A graph showing the relationship between the magnetic field and resistance change of a magnetoresistive element, and FIG. 5 is a perspective view showing a conventional example. 1! ... Substrate, 12 ... Ferromagnetic metal thin film, 12a ... Magnetoresistive element, 1
2b, 12d...Power supply terminal, 12c...
・Signal output terminal, 13...-conductor pattern, 13a, 13b...power supply terminal, 14.15...
...Through hole. 51 Σ 42 Engineering

Claims (1)

[Claims] 1. Consisting of a substrate, a magnetoresistive element made of a ferromagnetic metal thin film formed on the surface of the substrate, and a conductive thin film formed on the back side of the substrate and having a predetermined pattern, the magnetoresistive element is formed by energizing the conductive thin film. A magnetoresistive element characterized by forming a magnetic field for magnetic bias against.