JP2019163934A - Magnetic sensor - Google Patents

Abstract

To provide a magnetic sensor capable of reducing leakage of magnetic flux collected by an external magnetic body.SOLUTION: A magnetic sensor is provided, comprising a sensor substrate 20 with an element-forming surface 20a having magneto-sensitive elements R1-R4 formed thereon, and an external magnetic body 30A disposed between the magneto-sensitive elements R1, R3 and the magneto-sensitive elements R2, R4 viewing from a Z-direction. The external magnetic body 30A has a wide portion 31A covering the element-forming surface 20a, and a protruding portion 32A protruding from the wide portion 31A in the z-direction and having an x-direction width that is smaller than that of the wide portion 31A. In an x-z cross-section, an outer edge L of the wide portion 31A connecting an edge E1 and a boundary E2 has no corners. According to the present invention, the absence of corners on the wide portion 31A of the external magnetic body 30A enables reduction in leakage of magnetic flux collected by the external magnetic body 30A. This in turn allows for achieving higher detection accuracy.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor including a sensor substrate on which a magnetosensitive element is formed and an external magnetic body.

  In addition to a sensor substrate on which a magnetosensitive element is formed, an external magnetic material for collecting magnetic flux on the magnetosensitive element may be used for the magnetic sensor. For example, in the magnetic sensor described in Patent Document 1, two magnetosensitive elements are formed on the element forming surface of the sensor substrate, and an external magnetic body is disposed between the two magnetosensitive elements in plan view. . The external magnetic body of Patent Document 1 has a shape protruding in a direction perpendicular to the element formation surface, and the width in the vicinity of the element formation surface is enlarged. As a result, the magnetic flux collected by the external magnetic material is bent more greatly in the vicinity of the magnetic sensing element, thereby increasing the horizontal component of the magnetic flux in the vicinity of the magnetic sensing element, thereby increasing the detection sensitivity of the magnetic flux. .

Japanese Patent Laid-Open No. 2006-170166

  However, in the magnetic sensor described in Patent Document 1, since the wide part of the external magnetic body has a corner, the magnetic field concentrates on the corner, and the collected magnetic flux may leak from the corner. was there.

  Accordingly, an object of the present invention is to provide a magnetic sensor capable of reducing leakage of magnetic flux collected by an external magnetic material.

  A magnetic sensor according to the present invention includes a sensor substrate having an element formation surface on which first and second magnetosensitive elements arranged in a first direction are formed, and a second direction perpendicular to the element formation surface. As shown, the external magnetic body is disposed between the first magnetic sensitive element and the second magnetic sensitive element, and the external magnetic body has a wide portion covering the element formation surface, and a second direction from the wide portion. And a projecting portion whose width in the first direction is narrower than that of the wide portion, and the wide portion is a third perpendicular to the first and second directions along the first or second magnetosensitive element. In the cross section in the first and second directions of the wide portion, a corner portion is formed at the outer edge connecting the edge portion and the boundary portion. It is not provided.

  According to the present invention, since the wide portion of the external magnetic body does not have a corner, leakage of magnetic flux collected by the external magnetic body can be reduced. As a result, higher detection sensitivity can be obtained.

  In the present invention, the outer edge may be a straight line, a concave arc shape, or a convex arc shape. In any of these shapes, leakage of magnetic flux from the wide portion can be reduced.

  Thus, according to the present invention, it is possible to reduce leakage of magnetic flux collected by the external magnetic material. As a result, higher detection sensitivity can be obtained.

FIG. 1 is a schematic perspective view showing an appearance of a magnetic sensor 10A according to the first embodiment of the present invention. FIG. 2 is a schematic top view of the magnetic sensor 10A. FIG. 3 is a schematic cross-sectional view along the line AA shown in FIG. FIG. 4 is a circuit diagram for explaining a connection relationship between the magnetosensitive elements R1 to R4 and the terminal electrodes 41 to 44. FIG. 5 is a partial xz sectional view for explaining the shape of the external magnetic body 30A. FIG. 6 is a partial xz sectional view for explaining the shape of the external magnetic body 30a according to the first comparative example. FIG. 7 is a partial xz sectional view for explaining the shape of the external magnetic body 30b according to the second comparative example. FIG. 8 is an xz sectional view of a magnetic sensor 10B according to the second embodiment of the present invention. FIG. 9 is an xz sectional view of a magnetic sensor 10C according to the third embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a schematic perspective view showing an appearance of a magnetic sensor 10A according to the first embodiment of the present invention. 2 is a schematic top view of the magnetic sensor 10A, and FIG. 3 is a schematic cross-sectional view along the line AA shown in FIG.

  As shown in FIGS. 1 to 3, the magnetic sensor 10 </ b> A according to the present embodiment includes a sensor substrate 20 and an external magnetic body 30 </ b> A added to the sensor substrate 20. The sensor substrate 20 is a chip component, and magnetosensitive elements R1 to R4 are formed on an element forming surface 20a constituting the xy plane. The magnetic sensitive elements R1 to R4 are covered with a protective film 21. As a method for producing the sensor substrate 20, a method is generally used in which a large number of sensor substrates 20 are simultaneously formed on a collective substrate, and a large number are separated by separating them, but the present invention is not limited thereto. Alternatively, the individual sensor substrates 20 may be manufactured separately.

  The magnetosensitive elements R1 to R4 are not particularly limited as long as the physical characteristics change depending on the magnetic flux density, but are preferably magnetoresistive elements whose electric resistance changes according to the direction of the magnetic field. In the present embodiment, the magnetic sensing directions (fixed magnetization directions) of the magnetic sensing elements R1 to R4 are all aligned in the direction indicated by the arrow P in FIG. 2 (plus side in the x direction).

  An external magnetic body 30A is disposed substantially at the center in the x direction of the element formation surface 20a. The external magnetic body 30A is a block made of a soft magnetic material having high magnetic permeability such as ferrite, and may be adhered to the protective film 21 of the sensor substrate 20 using an adhesive or the like. The relative positional relationship with the sensor substrate 20 may be fixed.

  The external magnetic body 30A is disposed between the magnetic sensing elements R1, R3 and the magnetic sensing elements R2, R4 as viewed from the z direction. As a result, the magnetic flux φ collected by the external magnetic body 30A is distributed substantially evenly to the left and right. At this time, since a part of the magnetic flux φ passes through the magnetic sensing elements R1 to R4, magnetic fluxes in opposite directions are given to the magnetic sensing elements R1, R3 and the magnetic sensing elements R2, R4. As described above, since the magnetization fixed directions of the magnetosensitive elements R1 to R4 are aligned in the x plus direction indicated by the arrow P, the magnetosensitive elements R1 to R4 have sensitivity to the component in the x direction of the magnetic flux.

  FIG. 4 is a circuit diagram for explaining a connection relationship between the magnetosensitive elements R1 to R4 and the terminal electrodes 41 to 44.

  As shown in FIG. 4, the ground potential GND and the power supply potential Vdd are supplied to the terminal electrodes 41 and 44, respectively. Further, between the terminal electrodes 41 and 44, the magnetosensitive elements R1 and R2 are connected in series, and the magnetosensitive elements R4 and R3 are connected in series. The connection points of the magnetic sensitive elements R3 and R4 are connected to the terminal electrode 42, and the connection points of the magnetic sensitive elements R1 and R2 are connected to the terminal electrode 43. By such a full-bridge connection, by referring to the potential Va appearing at the terminal electrode 43 and the potential Vb appearing at the terminal electrode 42, changes in the electrical resistance of the magnetosensitive elements R1 to R4 corresponding to the magnetic flux density can be detected with high sensitivity. It becomes possible to do.

  Specifically, since all of the magnetosensitive elements R1 to R4 have the same magnetization fixed direction, the resistance change amount of the magnetosensitive elements R1 and R3 located on the left side of the external magnetic body 30A and the external magnetic body There is a difference between the resistance change amounts of the magnetosensitive elements R2 and R4 located on the right side of 30A. This difference is doubled by the full bridge circuit shown in FIG. 4 and appears on the terminal electrodes 42 and 43. Therefore, the magnetic flux density can be measured by detecting the difference between the potentials Va and Vb appearing at the terminal electrodes 42 and 43.

  FIG. 5 is a partial xz sectional view for explaining the shape of the external magnetic body 30A.

  As shown in FIG. 5, the external magnetic body 30A used in the present embodiment includes a wide portion 31A that covers the element forming surface 20a and a protruding portion 32A that protrudes in the z direction from the wide portion 31A. The wide portion 31A has a tapered shape in which the width in the x direction increases as it approaches the z direction with respect to the element formation surface 20a, and the maximum width in the x direction is W1. On the other hand, the width W2 in the x direction of the protruding portion 32A is constant and is narrower than the width W1 in the x direction of the wide portion 31A. Because of having such a shape, the z-direction magnetic flux φ collected by the protrusion 32A of the external magnetic body 30A is bent in the horizontal direction by the wide portion 31A, and the x-direction component increases. As a result, more magnetic flux of the x direction component is applied to the magnetic sensitive elements R1 to R4, so that the detection sensitivity is enhanced.

  Further, the xz cross section of the external magnetic body 30A has an edge portion E1 that is the tip of the wide portion 31A, and a boundary portion E2 that is a boundary between the wide portion 31A and the protruding portion 32A, and connects the edge portion E1 and the boundary portion E2. The outer edge L is not provided with corners and is straight. Here, the edge portion E1 is a tip portion extending in the y direction along the magnetosensitive elements R1 to R4, and since the xz cross section is an acute angle, the magnetic field concentrates on the edge portion E1, and many Magnetic flux is emitted from here. The edge portion E1 is located immediately above the element forming surface 20a, and the distance from the magnetic sensitive elements R1 to R4 is very close. Therefore, the x-direction component of the magnetic flux emitted from the edge portion E1 is the magnetic sensitive element R1. It is efficiently applied to ~ R4.

  Moreover, since the outer edge L connecting the edge portion E1 and the boundary portion E2 is a straight line and no corner portion is provided, leakage of magnetic flux taken into the external magnetic body 30A is reduced.

  FIG. 6 is a partial xz sectional view for explaining the shape of the external magnetic body 30a according to the first comparative example.

  The external magnetic body 30a shown in FIG. 6 includes a wide portion 31a that covers the element forming surface 20a and a protruding portion 32a that protrudes in the z direction from the wide portion 31a, like the external magnetic body 30A shown in FIG. The xz cross section of the wide portion 31a is rectangular, and the width in the x direction is substantially constant. In the external magnetic body 30a having such a shape, since the corner E3 is included in the outer edges L1 and L2 connecting the edge E1 and the boundary E2, a part of the magnetic flux taken into the external magnetic body 30a is a corner. It concentrates on E3 and a leakage magnetic flux is generated from here. As a result, since the magnetic flux applied to the magnetic sensitive elements R1 to R4 is reduced, the detection sensitivity is lowered.

  Such a problem can be alleviated to some extent by chamfering the corners of the wide portion 31b as in the external magnetic body 30b according to the second comparative example shown in FIG. However, even in this case, the outer edges L3 to L5 connecting the edge portion E1 and the boundary portion E2 include corner portions E4 and E5 that are obtuse angles, so that the magnetic flux that has reached the wide portion 31b via the protruding portion 32b. Is concentrated on the corners E4 and E5, and a leakage magnetic flux is generated therefrom.

  On the other hand, in the magnetic sensor 10A according to the present embodiment, since the external magnetic body 30A has the shape described above, the leakage of the magnetic flux taken into the external magnetic body 30A is small, and more magnetic flux is sensed. Application to the elements R1 to R4 becomes possible. As a result, higher detection sensitivity can be obtained.

<Second Embodiment>
FIG. 8 is an xz sectional view of a magnetic sensor 10B according to the second embodiment of the present invention.

  As shown in FIG. 8, the magnetic sensor 10B according to the present embodiment is different from the magnetic sensor 10A according to the first embodiment in that an external magnetic body 30B is used instead of the external magnetic body 30A. Since other configurations are the same as those of the magnetic sensor 10A according to the first embodiment, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  Similarly to the external magnetic body 30A, the external magnetic body 30B used in the present embodiment includes a wide portion 31B that covers the element formation surface 20a and a protruding portion 32B that protrudes from the wide portion 31B in the z direction. The wide portion 31B has a shape in which the width in the x direction is increased and the amount of expansion is increased as the element formation surface 20a is closer to the z direction. That is, the outer edge L connecting the edge portion E1 and the boundary portion E2 has a concave arc shape, and no corner portion is provided. Even when the external magnetic body 30B having such a shape is used, the same effect as that of the magnetic sensor 10A according to the first embodiment can be obtained, and the edge E1 has a more acute angle. It is possible to further increase the x-direction component of the magnetic flux applied to the magnetic sensitive elements R1 to R4.

<Third Embodiment>
FIG. 9 is an xz sectional view of a magnetic sensor 10C according to the third embodiment of the present invention.

  As shown in FIG. 9, the magnetic sensor 10C according to the present embodiment is different from the magnetic sensor 10A according to the first embodiment in that an external magnetic body 30C is used instead of the external magnetic body 30A. Since other configurations are the same as those of the magnetic sensor 10A according to the first embodiment, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  Similarly to the external magnetic body 30A, the external magnetic body 30C used in the present embodiment includes a wide portion 31C that covers the element formation surface 20a and a protruding portion 32C that protrudes from the wide portion 31C in the z direction. The wide portion 31 </ b> C has a shape in which the width in the x direction increases and the amount of enlargement decreases as the element formation surface 20 a approaches the z direction. That is, the outer edge L connecting the edge portion E1 and the boundary portion E2 is a convex arc shape, and no corner portion is provided. Even when the external magnetic body 30C having such a shape is used, the same effect as that of the magnetic sensor 10A according to the first embodiment can be obtained, and the angle of the edge portion E1 is relaxed. The mechanical strength of the external magnetic body 30C can be increased.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

10A, 10B, 10C Magnetic sensor 20 Sensor substrate 20a Element formation surface 21 Protective films 30A, 30B, 30C, 30a, 30b External magnetic bodies 31A, 31B, 31C, 31a, 31b Wide portions 32A, 32B, 32C, 32a, 32b Projecting Portions 41 to 44 Terminal electrode E1 Edge portion E2 Border portions E3 to E5 Corner portions L, L1 to L5 Outer edges R1 to R4 Magnetosensitive element φ Magnetic flux

Claims (4)

A sensor substrate having an element formation surface on which first and second magnetosensitive elements arranged in a first direction are formed;
An external magnetic body disposed between the first magnetic sensitive element and the second magnetic sensitive element when viewed from a second direction perpendicular to the element forming surface;
The external magnetic body includes a wide portion that covers the element forming surface, and a protruding portion that protrudes from the wide portion in the second direction and whose width in the first direction is narrower than the wide portion,
The wide portion is a boundary between the protruding portion and an edge portion extending in a third direction orthogonal to the first and second directions along the first or second magnetosensitive element. A boundary portion,
In the cross section of the wide portion in the first and second directions, a corner portion is not provided at an outer edge connecting the edge portion and the boundary portion.   The magnetic sensor according to claim 1, wherein the outer edge is a straight line.   The magnetic sensor according to claim 1, wherein the outer edge has a concave arc shape.   The magnetic sensor according to claim 1, wherein the outer edge has a convex arc shape.

Images