JP7119351B2 - magnetic sensor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor having a sensor substrate on which a magneto-sensitive element is formed and an external magnetic body.

Magnetic sensors using magneto-sensitive elements are widely used in ammeters, magnetic encoders, and the like. As described in Patent Document 1, the magnetic sensor may be provided with an external magnetic body for concentrating magnetic flux on the magneto-sensitive element. For example, the magnetic sensor described in FIG. 8 of Patent Document 1 includes a magnetic body 21 covering the central portion of the element forming surface of the sensor substrate, a magnetic body 22 covering the left side of the sensor substrate, and a right side of the sensor substrate. a magnetic body 23 covering the magneto-sensitive elements, and distributing the magnetic flux to the magneto-sensitive elements by disposing the magneto-sensitive elements between the magnetic bodies 21 and 22 and between the magnetic bodies 21 and 23, respectively. there is

Japanese Patent No. 5500785

However, when an external magnetic body is arranged on the element forming surface of the sensor substrate as in the magnetic sensor described in Patent Document 1, the element forming surface of the sensor substrate and the external magnetic body rub against each other during manufacturing, which causes the sensor substrate to rub against each other. There is a possibility that the device formation surface of the device may be damaged.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to reduce damage to an element forming surface of a sensor substrate in a magnetic sensor including a sensor substrate and an external magnetic body.

A magnetic sensor according to the present invention comprises a sensor substrate having an element forming surface on which one or more magnetosensitive elements are formed and a back surface located opposite to the element forming surface, and one or more external magnetic bodies. The external magnetic body includes a first external magnetic body covering the back surface of the sensor substrate, and the element forming surface of the sensor substrate is exposed without being covered with the external magnetic body.

According to the present invention, since the external magnetic flux is collected by the first external magnetic body, it is possible to enhance the detection sensitivity of the magnetic field. Moreover, since the element forming surface of the sensor substrate is exposed without being covered with the external magnetic material, the element forming surface of the sensor substrate and the external magnetic material do not rub against each other during manufacturing. This makes it possible to reduce damage that may be applied to the element forming surface of the sensor substrate during manufacturing.

In the present invention, the sensor substrate further has first and second side surfaces which are substantially orthogonal to the element forming surface and the back surface and are located on opposite sides, and the external magnetic body covers the first side surface of the sensor substrate. A second external magnetic body and a third external magnetic body covering the second side surface of the sensor substrate may be further included. According to this, it is possible to further enhance the detection sensitivity of the magnetic field.

In the present invention, the magneto-sensitive element includes the first and second magneto-sensitive elements having the same sensitivity direction, and the first external magnetic body is the same as the first magneto-sensitive element and the second magneto-sensitive element in plan view. It may be arranged in the region between the magnetic elements. According to this, the direction of the magnetic flux perpendicular to the element formation surface of the sensor substrate is bent in the horizontal direction by the external magnetic body, and as a result, the magnetic flux is applied to the first magneto-sensitive element and the second magneto-sensitive element. are in opposite directions to each other. This makes it possible to obtain a differential signal from the first and second magneto-sensitive elements.

In the present invention, the sensor substrate further has first and second side surfaces which are substantially orthogonal to the element forming surface and the back surface and which are located opposite to each other. Further comprising an external magnetic body, the first external magnetic body is arranged offset in the first lateral direction on the back surface, and the second external magnetic body is arranged offset in the second lateral direction on the back surface It doesn't matter if With such a layout as well, the direction of the magnetic flux perpendicular to the element forming surface of the sensor substrate can be bent in the horizontal direction by the external magnetic body.

In the present invention, the magneto-sensitive elements have the same sensitivity direction and are offset in the direction of the first side surface on the element-forming surface, and the second side surface on the element-forming surface. and a second magneto-sensitive element that is offset in the direction of the first magneto-sensitive element. The second external magnetic body is arranged with a large offset in the side direction of the second magneto-sensitive element, and the second external magnetic body is offset more in the second side direction than the second magneto-sensitive element without overlapping the second magneto-sensitive element in a plan view. It does not matter if the According to this, the magnetic flux bent in the horizontal direction by the first external magnetic body is applied to the first magneto-sensitive element, and the magnetic flux bent in the horizontal direction by the second external magnetic body is applied to the second magneto-sensitive element. Since it is applied to the elements, it is possible to obtain a differential signal from the first and second magneto-sensitive elements.

The magnetic sensor according to the present invention may further include a magnetic layer provided on the element forming surface of the sensor substrate. According to this, since the magnetic layer serves as a magnetic path on the element forming surface of the sensor substrate, the magnetic resistance is greatly reduced. This makes it possible to further improve the detection sensitivity.

The magnetic sensor according to the present invention may further comprise a circuit board on which the sensor substrate and the external magnetic material are mounted, and the sensor substrate may be mounted such that the element forming surface is substantially perpendicular to the mounting surface of the circuit substrate. do not have. By mounting the sensor substrate lying on the circuit board in this way, even if the external magnetic body is long, it is possible to stably support the external magnetic body on the circuit board.

The magnetic sensor according to the present invention may further include a circuit board on which the sensor substrate and the external magnetic material are mounted, and the sensor substrate may be mounted so that the element forming surface faces the mounting surface of the circuit board. According to this, since the element formation surface is covered with the mounting surface of the circuit board, the element formation surface of the sensor substrate is less likely to be damaged not only during manufacturing but also during actual use.

Thus, according to the present invention, since the element forming surface of the sensor substrate is exposed without being covered with the external magnetic material, the element forming surface of the sensor substrate and the external magnetic material do not rub against each other during manufacturing. . This makes it possible to reduce the damage applied to the element forming surface of the sensor substrate.

FIG. 1 is a schematic cross-sectional view of a magnetic sensor 11 according to a first embodiment of the invention. FIG. 2 is a schematic plan view of the magnetic sensor 11 according to the first embodiment of the invention. FIG. 3 is a schematic diagram for explaining the flow of the magnetic flux φ in the magnetic sensor 11. As shown in FIG. FIG. 4 is a circuit diagram for explaining the connection relationship of the magneto-sensitive elements R1 to R4. FIG. 5 is a schematic perspective view for explaining an example of a mounting method of the magnetic sensor 11. FIG. FIG. 6 is a schematic perspective view for explaining another example of the mounting method of the magnetic sensor 11. As shown in FIG. FIG. 7 is a plan view of a magnetic sensor 11A according to a modification. FIG. 8 is a schematic cross-sectional view of a magnetic sensor 12 according to a second embodiment of the invention. FIG. 9 is a schematic diagram for explaining the flow of the magnetic flux φ in the magnetic sensor 12. As shown in FIG. FIG. 10 is a schematic perspective view for explaining an example of a mounting method of the magnetic sensor 12. As shown in FIG. FIG. 11 is a cross-sectional view of a magnetic sensor 13 according to a third embodiment of the invention. FIG. 12 is a schematic diagram for explaining the flow of the magnetic flux φ in the magnetic sensor 13. As shown in FIG. FIG. 13 is a schematic perspective view for explaining an example of a mounting method of the magnetic sensor 13. As shown in FIG.

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

<First Embodiment>
1 and 2 are schematic cross-sectional and schematic plan views, respectively, of a magnetic sensor 11 according to a first embodiment of the present invention. Here, FIG. 1 shows a cross section along line AA shown in FIG.

As shown in FIGS. 1 and 2 , the magnetic sensor 11 according to this embodiment includes a sensor substrate 20 and a first external magnetic body 31 added to the sensor substrate 20 . The sensor substrate 20 is a chip component, and the general method of manufacturing it is to simultaneously form a large number of sensor substrates 20 on a collective substrate and separate them to obtain a large number of them. , and each sensor substrate 20 may be manufactured separately.

The sensor substrate 20 has a substantially rectangular parallelepiped shape, and four magneto-sensitive elements R1 to R4 are formed on an element forming surface 20a forming an xy plane. The magneto-sensitive elements R1 to R4 are not particularly limited as long as they are elements whose physical properties change depending on the magnetic flux density, but they are preferably magneto-resistive elements whose electric resistance changes according to the direction of the magnetic field. In this embodiment, the sensitivity directions (fixed magnetization directions) of the magneto-sensitive elements R1 to R4 are all aligned in the direction indicated by the arrow P in FIG. 2 (the positive side in the x direction). An insulating film 21 is formed on the element forming surface 20a to protect the magneto-sensitive elements R1 to R4. Here, the element forming surface 20a refers not only to the surface of the sensor substrate 20 itself, but also to the surfaces of the insulating films when one or more insulating films are formed on the surface of the sensor substrate 20. It constitutes the forming surface 20a. As shown in FIG. 2, terminal electrodes E11 to E14 are also formed on the element forming surface 20a.

The first external magnetic body 31 is a block made of a soft magnetic material with high magnetic permeability such as ferrite. The first external magnetic body 31 is arranged to cover the rear surface 20b of the sensor substrate 20 . The back surface 20b of the sensor substrate 20 is an xy plane located on the opposite side of the element formation surface 20a of the sensor substrate 20, and no magneto-sensitive elements or terminal electrodes are formed thereon. On the other hand, the element forming surface 20a of the sensor substrate 20 is exposed without being covered with the external magnetic material.

The first external magnetic body 31 is arranged between the magneto-sensitive elements R1, R3 and the magneto-sensitive elements R2, R4 in plan view, that is, in the z-direction, and is a rectangular parallelepiped having the z-direction as its longitudinal direction. have a shape. As shown in FIG. 3, the first external magnetic body 31 serves to collect the magnetic flux φ in the z direction by bending it in the x direction. As a result, when a magnetic flux φ is generated in the z direction, a magnetic field component in the x direction, which is the sensitivity direction, is applied to the magneto-sensitive elements R1 to R4. The height of the first external magnetic body 31 in the z direction is not particularly limited, but by increasing the height in the z direction, the selectivity of the magnetic flux in the z direction can be enhanced. In the present embodiment, the width of the first external magnetic body 31 in the y direction substantially matches the width of the sensor substrate 20 in the y direction, but the present invention is not limited to this.

FIG. 4 is a circuit diagram for explaining the connection relationship of the magneto-sensitive elements R1 to R4.

As shown in FIG. 4, the magnetic sensor 11 according to this embodiment has four terminal electrodes E11 to E14, and the terminal electrodes E11 and E14 are supplied with a ground potential Gnd and a power supply potential Vdd, respectively. Between the terminal electrodes E11 and E14, magneto-sensitive elements R1 and R2 are connected in series, and magneto-sensitive elements R4 and R3 are connected in series. A connection point between the magneto-sensitive elements R3 and R4 is connected to the terminal electrode E12, and a connection point between the magneto-sensitive elements R1 and R2 is connected to the terminal electrode E13. With such a bridge connection, by referring to the potential Va appearing at the terminal electrode E13 and the potential Vb appearing at the terminal electrode E12, changes in the electrical resistance of the magneto-sensitive elements R1 to R4 corresponding to the magnetic flux density can be detected with high sensitivity. becomes possible.

Specifically, since all of the magneto-sensitive elements R1 to R4 have the same fixed magnetization direction, the resistance change amount of the magneto-sensitive elements R1 and R3 positioned on one side of the first external magnetic body 31 is , and the amount of resistance change of the magneto-sensitive elements R2 and R4 located on the other side as viewed from the first external magnetic body 31. As shown in FIG. This difference is amplified twice by the differential bridge circuit shown in FIG. 4 and appears at terminal electrodes E12 and E13. Therefore, the magnetic flux density can be measured by detecting the difference between the potentials Va and Vb appearing at the terminal electrodes E12 and E13.

Thus, since the magnetic sensor 11 according to the present embodiment includes the first external magnetic body 31, it can selectively detect the magnetic flux in the z direction. Moreover, in the magnetic sensor 11 according to the present embodiment, since the element forming surface 20a of the sensor substrate 20 is exposed without being covered with the external magnetic material, the element forming surface 20a and the external magnetic material may rub against each other during manufacturing. No problem. This makes it possible to reduce the damage applied to the element formation surface 20a.

FIG. 5 is a schematic perspective view for explaining an example of a mounting method of the magnetic sensor 11 according to this embodiment.

In the example shown in FIG. 5, the xz plane of the circuit board 40 is the mounting surface 41, and the magnetic sensor 11 is mounted on this mounting surface 41 with the magnetic sensor 11 laid down at an angle of 90 degrees. In other words, the sensor substrate 20 is mounted so that the element forming surface 20a of the sensor substrate 20 is substantially perpendicular to the mounting surface 41 of the circuit substrate 40 . Land patterns E21 to E24 are provided on the mounting surface 41 of the circuit board 40, and these land patterns E21 to E24 are connected via solder S to terminal electrodes E11 to E14, respectively. According to such a mounting method, since the first external magnetic body 31 can be fixed to the circuit board 40, even if the length in the z direction of the first external magnetic body 31 is long, the It becomes possible to stably support one external magnetic body 31 . Further, in this example, since the first external magnetic body 31 can be fixed to the circuit board 40, it is not always necessary to bond the back surface 20b of the sensor substrate 20 and the first external magnetic body 31 together.

FIG. 6 is a schematic perspective view for explaining another example of the mounting method of the magnetic sensor 11 according to this embodiment.

In the example shown in FIG. 6, the xy plane of the circuit board 40 is the mounting surface 41, and the magnetic sensor 11 is mounted upright so that the element forming surface 20a of the sensor substrate 20 faces the mounting surface 41 of the circuit board 40. . Land patterns E21 to E24 are provided on the mounting surface 41 of the circuit board 40, and these land patterns E21 to E24 are connected via solder S to terminal electrodes E11 to E14, respectively. When the magnetic sensor 11 is mounted in an upright position as in this example, the terminal electrodes E11 to E14 are not collectively arranged in one place, but arranged dispersedly near the outer periphery of the element forming surface 20a. The sensor 11 can be stably fixed to the circuit board 40 . According to such a mounting method, since the element forming surface 20a of the sensor substrate 20 faces downward, the element forming surface 20a is protected even in actual use and is less likely to be damaged.

FIG. 7 is a plan view of a magnetic sensor 11A according to a modification.

A magnetic sensor 11A shown in FIG. 7 differs from the magnetic sensor 11 shown in FIG. The magnetic layer M1 is located substantially in the center of the element forming surface 20a, and the magnetic layers M2 and M3 are arranged on both sides thereof in the x direction. Magneto-sensitive elements R1 and R3 are arranged in the gap formed by the magnetic layer M1 and the magnetic layer M2, and magneto-sensitive elements R2 and R4 are arranged in the gap formed by the magnetic layer M1 and the magnetic layer M3. be done. Although not particularly limited, the magnetic layers M1 to M3 may be films made of a composite magnetic material in which a magnetic filler is dispersed in a resin material, or may be made of a soft magnetic material such as nickel or permalloy. It may be a thin film or foil, or a thin film or bulk sheet made of ferrite or the like.

If such magnetic layers M1 to M3 are provided on the element forming surface 20a, the magnetic resistance is lowered and the magnetic flux φ efficiently passes through the magnetosensitive elements R1 to R4, so that detection accuracy can be improved. Become.

<Second embodiment>
FIG. 8 is a schematic cross-sectional view of a magnetic sensor 12 according to a second embodiment of the invention.

As shown in FIG. 8, the magnetic sensor 12 according to the second embodiment differs from the magnetic sensor 11 according to the first embodiment in that a second external magnetic body 32 and a third external magnetic body 33 are added. is different from Since other configurations are the same as those of the magnetic sensor 11 according to the first embodiment, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

The second external magnetic body 32 is provided covering the first side surface 20 c of the sensor substrate 20 , and the third external magnetic body 33 is provided covering the second side surface 20 d of the sensor substrate 20 . Here, the first and second side surfaces 20c, 20d constitute a yz plane and are located opposite to each other. The second and third external magnetic bodies 32 and 33 are blocks made of a soft magnetic material with high magnetic permeability such as ferrite, and may be made of the same material as the first external magnetic body 31 . The second and third external magnetic bodies 32 and 33 cover the first and second side surfaces 20c and 20d of the sensor substrate 20, respectively, and have portions protruding upward.

As a result, as shown in FIG. 9, the magnetic field component in the x direction applied to the magneto-sensitive elements R1 to R4 is increased, so that the magnetic field detection sensitivity can be further increased. Here, in order to further increase the magnetic field detection sensitivity, the lower ends (xy end surfaces on the back surface 20b side) of the second and third external magnetic bodies 32 and 33 should be positioned as close to the element forming surface 20a of the sensor substrate 20 as possible. is preferred.

As shown in FIG. 10, the magnetic sensor 12 according to the present embodiment can be mounted on the mounting surface 41 forming the xz plane of the circuit board 40 at an angle of 90 degrees. According to this mounting method, since the first to third external magnetic bodies 31 to 33 can be fixed to the circuit board 40, the lengths of the first to third external magnetic bodies 31 to 33 in the z direction Even if the length is long, the first to third external magnetic bodies 31 to 33 can be stably supported. Further, according to the mounting method shown in FIG. 10, the second and third external magnetic bodies 32 and 33 can be fixed to the circuit board 40, so that the side surfaces 20c and 20d of the sensor board 20 and the second and third It is not always necessary to bond the external magnetic bodies 32 and 33 of .

<Third Embodiment>
FIG. 11 is a cross-sectional view of a magnetic sensor 13 according to a third embodiment of the invention.

As shown in FIG. 11, the magnetic sensor 13 according to the third embodiment has a second external magnetic body 32 added, and both the first and second external magnetic bodies 31 and 32 extend in the x direction. It differs from the magnetic sensor 11 according to the first embodiment in that it is arranged with an offset. Since other configurations are the same as those of the magnetic sensor 11 according to the first embodiment, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

The first external magnetic body 31 is arranged on the rear surface 20b of the sensor substrate 20 so as to be offset in the direction of the first side surface 20c. Similarly, the second external magnetic body 32 is arranged on the rear surface 20b of the sensor substrate 20 so as to be offset in the direction of the second side surface 20d. In particular, the first external magnetic body 31 is arranged with a large offset in the direction of the first side surface 20c relative to the magneto-sensitive elements R2 and R4, so that it does not overlap with the magneto-sensitive elements R2 and R4 when viewed from the z direction. is preferred. Similarly, the second external magnetic body 32 is arranged with a large offset in the direction of the second side surface 20d relative to the magneto-sensitive elements R1 and R3, so that it does not overlap with the magneto-sensitive elements R1 and R3 when viewed from the z direction. is preferred.

As a result, as shown in FIG. 12, the magnetic flux φ in the z direction is bent in the x direction, so that the magnetic field can be detected in the same manner as in the first embodiment. As exemplified in this embodiment, it is not essential in the present invention to dispose an external magnetic body between the magneto-sensitive elements R1, R3 and the magneto-sensitive elements R2, R4.

As shown in FIG. 13, the magnetic sensor 13 according to the present embodiment can be mounted on the mounting surface 41 forming the xz plane of the circuit board 40 at an angle of 90 degrees. According to such a mounting method, since the first and second external magnetic bodies 31 and 32 can be fixed to the circuit board 40, the lengths of the first and second external magnetic bodies 31 and 32 in the z direction Even if the length is long, it is possible to stably support the first and second external magnetic bodies 31 and 32 . Further, according to the mounting method shown in FIG. 13, since the first and second external magnetic bodies 31 and 32 can be fixed to the circuit board 40, the back surface 20b of the sensor board 20 and the first and second external magnetic bodies 31 and 32 can be fixed. It is not always necessary to bond the magnetic bodies 31 and 32 together.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. Needless to say, it is included within the scope.

For example, four magneto-sensitive elements R1 to R4 are used in each of the above-described embodiments, but the number of magneto-sensitive elements used in the present invention is not limited to this.

11, 11A, 12, 13 magnetic sensor 20 sensor substrate 20a element forming surface 20b element forming surface rear surface 20c element forming surface first side surface 20d element forming surface second side surface 21 insulating film 31 first external magnetic body 32 second external magnetic body 33 third external magnetic body 40 circuit board 41 circuit board mounting surface E11-E14 terminal electrodes E21-E24 land patterns M1-M3 magnetic layers R1-R4 magneto-sensitive element S solder φ magnetic flux

Claims (4)

an element forming surface on which one or more magnetosensitive elements are formed; a back surface positioned opposite to the element forming surface; and a second side surface, and a sensor substrate having a third side surface substantially orthogonal to the element formation surface, the back surface, the first side surface, and the second side surface;
1 or 2 or more external magnetic bodies;
a circuit board on which the sensor board and the external magnetic body are mounted;
The first and second side surfaces are substantially orthogonal to the sensitivity direction of the magneto-sensitive element,
The external magnetic bodies include a first external magnetic body covering the back surface of the sensor substrate, a second external magnetic body covering the first side surface of the sensor substrate, and the second side surface of the sensor substrate. and a third external magnetic body covering the
The element formation surface of the sensor substrate is exposed without being covered with the external magnetic body,
The sensor substrate is mounted with the third side facing the mounting surface such that the element forming surface is substantially perpendicular to the mounting surface of the circuit board ,
The magnetic sensor, wherein each of the second and third external magnetic bodies has a portion that protrudes upward beyond the element forming surface . The magneto-sensitive element includes first and second magneto-sensitive elements having the same sensitivity direction,
2. The magnetic sensor according to claim 1, wherein said first external magnetic body is arranged in a region between said first magneto-sensitive element and said second magneto-sensitive element in plan view. 3. The magnetic sensor according to claim 1, further comprising a magnetic layer provided on said element forming surface of said sensor substrate. a plurality of terminal electrodes arranged in a sensitivity direction of the magneto-sensitive element are provided on the element forming surface of the sensor substrate,
The mounting surface of the circuit board is provided with a plurality of land patterns arranged in a sensitivity direction of the magneto-sensitive element,
4. The magnetic sensor according to claim 1 , wherein the plurality of land patterns are connected to the plurality of terminal electrodes via solder.

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