JP2000077742A - Magnetoresistive element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoresistive element that can be improved in moisture-resistant reliability. SOLUTION: A magnetoresistor is equipped with two or more side electrodes 12 provided spreading over from the upper surface side to side faces of a board 11, a flat layer 13 that is provided nearly at the center of the board 11 so as not to come into contact with the side electrodes 12, wiring electrodes 14 provided over the side electrode 12 and the flat layer 13 crossing a gap between them, and a ferromagnetic thin film 15 provided on the upside of the flat layer 13. At this point, the wiring electrodes 14 are provided to the upside of the board 11 inside its edge so as not to reach its upper peripheral edge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element used for various electronic devices.

[0002]

2. Description of the Related Art A conventional magnetoresistive element will be described below with reference to the drawings.

As a conventional magnetoresistive element of this kind, there is known a magnetic resistance element described in a microfilm of Japanese Utility Model Application No. 1-86494 (Japanese Utility Model Application Laid-Open No. 3-27060).

FIG. 8 is a plan view of a conventional magnetoresistive element. In FIG. 8, reference numeral 1 denotes a chip-type substrate in which four corners are formed with notches having an arc-shaped cross section. 2 is a glaze layer provided so as to cover the upper surface of the substrate 1. Reference numeral 3 denotes a wiring electrode provided on the side of the upper surface of the glaze layer 2. 4
Is a magnetoresistive film provided on the upper surface of the glaze layer 2 so as to be electrically connected to the wiring electrode 3. 5 is a wiring electrode 3
It is an exposed electrode formed toward the rear surface of the substrate via the cutout side surface of the chip type substrate 1 so as to be electrically connected to the substrate. Further, a protective film is applied so as to cover the wiring electrodes 3 and the magnetoresistive film 4.

A method of manufacturing the conventional magnetoresistive element configured as described above will be described below with reference to the drawings.

When a conventional magnetoresistive element is manufactured, FIG.
A single alumina ceramic plate 7 having a large number of through holes 6 as shown in FIG. 1 and having cut lines 7a formed in the vertical and horizontal directions is used. First, a metal conductor is formed on the surface of the alumina ceramic plate 7. Is formed to form the wiring electrode 3.

Next, on the surface of the alumina ceramic plate 7,
The exposed electrode 5 is formed so as to surround the periphery of the through hole 6.

Next, after dividing the alumina ceramic plate 7 at the cut line 7a, a magnetoresistive film 4 such as permalloy is formed by vapor deposition on the chip type substrate 1 on which individual magnetoresistive elements are formed. Next, a conventional magnetoresistive element is formed by forming a protective film made of silicon dioxide or the like.

The operation of the conventional magnetoresistive element constructed and manufactured as described above will be described below with reference to the drawings.

FIG. 10 is a perspective view showing a conventional magnetic resistance element incorporated in a magnetic rotary encoder.

As shown in FIG. 10, a magnetic recording portion corresponding to the number of output pulses of the encoder is provided on the outer peripheral portion of the rotary drum 8 by alternately magnetizing the N pole and the S pole at a predetermined pitch. A laminated magnetoresistive element 9 is arranged close to the outside of the magnetic recording portion of the rotating drum 8. In this state, when the encoder shaft 10 of the magnetic rotary encoder rotates, the laminated magnetic resistance element 9 rotates the N pole and the S pole of the rotating drum 8 passing through the magnetoresistive film of the laminated magnetic resistance element 9. The magnetic rotary encoder detects a magnetic field and converts it into an electric signal. This magnetic rotary encoder is used to control the rotation speed and rotation angle of a rotating shaft.

[0012]

However, in the above conventional magnetoresistive element, the alumina ceramic plate 7
Is divided at the cut line 7a, the wiring electrode 3 is also divided at the same time. Therefore, as shown in FIG.
Since the wiring electrode 3 reaches the upper surface end of the chip-type substrate 1 and the wiring electrodes 3 are exposed on the side surfaces of the chip-type substrate 1, there is a problem that the reliability decreases in terms of moisture resistance. Was.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a magnetoresistive element capable of improving reliability in terms of moisture resistance.

[0014]

In order to achieve the above object, a magnetoresistive element according to the present invention comprises: a substrate; at least two side electrodes provided from at least a side of an upper surface of the substrate to a side surface; A flat layer provided substantially at the center of the substrate so as not to contact the side electrode, a wiring electrode provided so as to straddle the side electrode and the flat layer, and a ferromagnetic provided at least on the upper surface of the flat layer. A thin film, and an insulating protective layer provided so as to cover at least the exposed ferromagnetic thin film and the wiring electrode, wherein the wiring electrode is provided inside the upper surface of the substrate so as not to reach an end of the upper surface of the substrate. That
According to this configuration, reliability in terms of moisture resistance can be improved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a substrate, at least two side electrodes provided from at least a side of an upper surface of the substrate to a side surface, and a substantially central portion of the substrate. A flat layer provided so as not to contact the side electrode, a wiring electrode provided so as to straddle the side electrode and the flat layer, a ferromagnetic thin film provided at least on an upper surface of the flat layer, An insulating protective layer provided so as to cover the ferromagnetic thin film and the wiring electrode,
The wiring electrode is provided inside the upper surface of the substrate so as not to reach the upper end of the substrate. According to this configuration, the wiring electrode is provided inside the upper surface of the substrate so as not to reach the upper end of the substrate. Since the wiring electrodes are provided, the wiring electrodes are not exposed on the side surface of the substrate as in the related art, and as a result, the effect of improving reliability in terms of moisture resistance is obtained.

(Embodiment 1) Hereinafter, a magnetoresistive element according to Embodiment 1 will be described with reference to the drawings.

FIG. 1 is a plan view of a magnetoresistive element according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

In FIGS. 1 and 2, reference numeral 11 denotes a square substrate made of alumina or the like having notches 11a at four corners. 12 is a notch 11a at each of the four corners of the substrate 11.
Side electrodes made of silver-palladium or the like provided on the side of the lower surface through the side surface from the upper surface, and the side electrodes at the four corners are 12a, 12b, 12c, and 12d. 13
Is a flat layer made of glass or the like provided substantially in the center of the upper surface of the substrate 11 so as not to be in contact with the side electrode 12. The flat layer 13 is used for accurately patterning a ferromagnetic thin film made of permalloy or the like described later. It is forming.
Reference numeral 14 denotes the substrate 11 so as not to reach the upper end of the substrate 11.
A wiring electrode formed of nichrome, nickel, silver or the like formed inside the upper surface of
It is provided in a fan shape so as to straddle 2 and the flat layer 13.
Reference numeral 15 denotes a wiring electrode 14 on the upper surface of the flat layer 13 and the wiring electrode 14.
Is a ferromagnetic thin film having a desired pattern made of permalloy or the like provided so that a part of the ferromagnetic thin film is exposed.
m to 200 nm. P1, P2, P3, P
Numeral 4 denotes a magnetic sensing unit of the ferromagnetic thin film 15. 16
Is an insulating protective layer made of a phenolic resin or the like provided so as to cover at least the wiring electrode 14 and the ferromagnetic thin film 15. The insulating protective layer 16 prevents entry of moisture and the like from above the substrate 11. Things.

The method of manufacturing the magnetoresistive element configured as described above will be described below with reference to the drawings.

FIGS. 3A to 3E are process diagrams showing a method of manufacturing the magnetoresistive element according to the first embodiment of the present invention.

First, as shown in FIG. 3A, a thick film conductor paste made of silver-palladium is printed on the upper surface of an original substrate 22 made of alumina having a plurality of through holes 21 and dried. The side electrode 12 was formed by supplying a thick-film conductor paste made of silver-palladium to the lower surface of the substrate 22 and firing the paste.

Next, as shown in FIG. 3B, a mask made of glass is printed on the upper surface of the original substrate 22 with a mask having a pattern provided so as not to be in contact with the side electrode 12, and baked. By doing so, the flat layer 13 was formed.

Next, as shown in FIG.
A mask having a pattern provided so as not to extend over a line connecting the centers of the through holes 21 of the second through-hole 21 and straddling the side electrode 12 and the flat layer 13 is superimposed on the upper surface of the original substrate 22, and is formed on the first layer. The wiring electrode 14 was formed by vacuum-depositing nickel on the second layer of nichrome. In this case, the wiring electrode 14 is formed at a position having a distance of 30 μm or more from a line connecting the centers of the through holes 21 of the original substrate 22 in consideration of burrs at the time of division described later. Things.

Next, as shown in FIG.
A ferromagnetic thin film 15 having a desired pattern was formed by vacuum-depositing and etching a ferromagnetic material made of permalloy on the upper surfaces of the second wiring electrode 14 and the flat layer 13.

Next, as shown in FIG.
Using a mask provided so as to cover at least the wiring substrate 14 and the ferromagnetic thin film 15 on the upper surface of the substrate 2, a resin made of phenol was printed and baked to form the insulating protective layer 16.

Finally, in the original substrate 22, the magnetoresistive element according to the first embodiment of the present invention was formed by dividing into individual pieces between the adjacent through holes 21.

The magnetoresistive element according to the first embodiment of the present invention constructed and manufactured as described above and the conventional structure shown in FIG. In the product, the disconnection failure occurred in about 500 hours, but the magnetoresistive element according to the first embodiment of the present invention
No disconnection failure occurred even for 000 hours.

The operation of the magnetoresistive element constructed and manufactured as described above according to the first embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is an equivalent circuit diagram of the magnetoresistive element according to Embodiment 1 of the present invention, FIG. 5 is a schematic diagram showing the direction of application of a magnetic field to a magnetic sensing portion of the magnetoresistive element, and FIG. It is a perspective view showing the example of use of an element.

It is known that a magnetoresistive element using a ferromagnetic thin film can have a shape magnetic anisotropy by being processed into a strip shape. When a magnetic field is applied perpendicularly to the longitudinal direction, its resistance decreases. It is known to P1 to P4 in FIG. 1 are magnetic sensing units formed for such a purpose, and R1, R2, R3, and R4 shown in FIG. 4 are respective resistance values of the magnetic sensing units P1, P2, P3, and P4. .
As shown in FIG. 5, when a magnetic field H is applied to the magneto-resistive element 31, R1 and R3 show the same change in the resistance value due to the above-described relationship of the shape magnetic anisotropy, and the same intensity perpendicular to the magnetic field H. When the above magnetic field is applied, R2 and R4 show equivalent resistance value changes.

As shown in FIG. 6, a rotating drum 33 having N and S poles alternately magnetized and a magnetoresistive element 31 located on the outer periphery of the rotating drum 33 are provided on a mounting substrate 32. And in this FIG.
3 rotates, a leakage magnetic field from the rotating drum 33 is applied to the magnetoresistive element 31. Then, the resistance values of R1 and R3 change in the equivalent circuit diagram of FIG. In this case, since a constant voltage is applied between 12a and 12c in FIG. 4, the voltage dividing ratio between the resistors R1 and R2, R3 and R3
The voltage division ratio of the resistor 4 changes. When the strength of the leakage magnetic field fluctuates, the output voltages of 12b and 12d in FIG. By detecting the fluctuation of the output voltage, the rotation speed and the rotation angle of the rotating drum 33 are detected and controlled.

In the first embodiment of the present invention, the description has been given of the case where the wiring electrode 14 is made of nichrome, nickel, silver or the like. However, the wiring electrode 14 is formed of a relatively inexpensive material such as copper or aluminum. Even in this case, the same effect as in the first embodiment of the present invention can be obtained.

(Embodiment 2) Hereinafter, a magnetoresistive element according to Embodiment 2 of the present invention will be described with reference to the drawings.

FIG. 7 is a plan view of a magnetoresistive element according to Embodiment 2 of the present invention. Embodiment 2 of the present invention
The difference between the first embodiment of the present invention and the first embodiment of the present invention is that the first embodiment of the present invention has the wiring electrode 14 in a fan shape, whereas the second embodiment of the present invention has Is a bar. When the wiring electrode 14a is formed in a rod shape in this manner, the area is smaller than that of the fan shape, so that the pattern area of the ferromagnetic thin film 15 can be increased, and the adhesion between the flat layer 13 and the insulating protective layer 16 can be improved. Since the area can be increased, the reliability can be further improved.

[0035]

As described above, the magnetoresistive element of the present invention has the following features.
A substrate, at least two side electrodes provided from at least a side portion to a side surface of the upper surface of the substrate, a flat layer provided at a substantially central portion of the substrate so as not to contact the side electrodes, and the side electrode A wiring electrode provided so as to straddle the flat layer, a ferromagnetic thin film provided at least on the upper surface of the flat layer, and an insulating property provided so as to cover at least the exposed ferromagnetic thin film and the wiring electrode. A protective layer, wherein the wiring electrode is provided inside the upper surface of the substrate so as not to reach the upper surface edge of the substrate. According to this configuration, the wiring electrode does not reach the upper surface edge of the substrate. Since the wiring electrodes are provided inside the upper surface of the substrate, the wiring electrodes do not become exposed on the side surfaces of the substrate as in the past, and as a result, the excellent effect of improving reliability in terms of moisture resistance is obtained. Have That.

[Brief description of the drawings]

FIG. 1 is a plan view of a magnetoresistive element according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

3 (a) to 3 (e) are manufacturing process diagrams of the same magnetoresistive element.

FIG. 4 is an equivalent circuit diagram of the magnetoresistive element.

FIG. 5 is a schematic diagram showing a direction in which a magnetic field is applied to a magnetic sensing unit of the magnetoresistive element.

FIG. 6 is a perspective view showing a usage example of the magnetoresistive element.

FIG. 7 is a plan view of a magnetoresistive element according to Embodiment 2 of the present invention.

FIG. 8 is a plan view of a conventional magnetoresistive element.

FIG. 9 is an overall substrate view of the magnetoresistive element before division.

FIG. 10 is a perspective view showing a usage example of the magnetoresistive element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Substrate 12 Side electrode 13 Flat layer 14, 14a Wiring electrode 15 Ferromagnetic thin film 16 Insulating protective layer

Claims (1)

[Claims] 1. A substrate, and at least two side electrodes provided from at least a side of an upper surface to side surfaces of the substrate,
A flat layer provided substantially in the center of the substrate so as not to contact the side electrode, a wiring electrode provided so as to straddle the side electrode and the flat layer, and a strong electrode provided at least on an upper surface of the flat layer. A magnetic thin film, and an insulating protective layer provided so as to cover at least the exposed ferromagnetic thin film and the wiring electrode, wherein the wiring electrode is provided inside the upper surface of the substrate so as not to reach an end of the upper surface of the substrate. A magnetoresistive element characterized by being provided.