WO2017077871A1 - Magnetic sensor - Google Patents

Abstract

[Problem] To provide a magnetic sensor wherein a sensor chip and a magnetic body are more reliably fixed to each other, said magnetic sensor enabling to achieve a height reduction. {Solution] This magnetic sensor is provided with: a sensor chip 30 having an element forming surface 31, on which a magnetic detection element MR is formed, and a side surface 32 substantially perpendicular to the element forming surface 31; and a first magnetic body 41 that is provided on the side surface 32 of the sensor chip 30. According to the present invention, since the first magnetic body 41 is provided on the side surface 32 of the sensor chip 30, an area where the sensor chip 30 and the first magnetic body 41 are in contact with each other can be expanded. Consequently, the sensor chip and the first magnetic body can be more reliably fixed to each other. Furthermore, height reduction can be also achieved.

Description

Magnetic sensor

The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor provided with a magnetic body for collecting magnetic flux on a sensor chip.

Magnetic sensors using giant magnetoresistive elements are widely used in ammeters and magnetic encoders. The magnetic sensor may be provided with a magnetic body for collecting magnetic flux on the sensor chip. In this case, the magnetic body is placed on the element formation surface of the sensor chip (see Patent Document 1).

JP 2009-276159 A

However, since the sensor chip is generally small, it is not easy to place the magnetic body on the sensor chip, and it is difficult to securely fix the sensor chip and the magnetic body. In addition, when a magnetic material is placed on the element formation surface of the sensor chip, the overall height of the magnetic sensor increases, making it difficult to reduce the height.

Therefore, an object of the present invention is to provide a magnetic sensor capable of more securely fixing a sensor chip and a magnetic body and realizing a low profile.

The magnetic sensor according to the present invention includes an element formation surface on which at least one magnetic detection element is formed, a sensor chip having a side surface substantially perpendicular to the element formation surface, and a first provided on the side surface of the sensor chip. And a magnetic body.

According to the present invention, since the first magnetic body is provided on the side surface of the sensor chip, the contact area between the sensor chip and the magnetic body can be increased. For this reason, both can be fixed more reliably. Moreover, it is possible to realize a low profile.

The magnetic sensor according to the present invention preferably further includes a second magnetic body provided on the element forming surface of the sensor chip and in the vicinity of the side surface. According to this, since the magnetic flux in the vertical direction with respect to the element formation surface can be further bent in the horizontal direction, the detection sensitivity can be increased.

In the present invention, it is preferable that the magnetic detection element includes first and second magnetic detection elements, and the first and second magnetic detection elements have different distances from the side surface. According to this, magnetic detection can be performed using the output difference between the first magnetic detection element and the second magnetic detection element.

In this case, the magnetic detection element includes a third magnetic detection element having a distance from the side surface equal to that of the first magnetic detection element, and a fourth distance from the side surface being equal to that of the second magnetic detection element. It is preferable to further include a magnetic detection element. According to this, it is possible to form a differential bridge circuit using the first to fourth magnetic detection elements, and in this case, it is possible to perform magnetic detection with higher sensitivity.

The magnetic sensor according to the present invention preferably further comprises a circuit board having a mounting surface on which the sensor chip is mounted. In this case, the element formation surface of the sensor chip may be substantially parallel to the mounting surface of the circuit board, or may be substantially perpendicular to the mounting surface of the circuit board.

According to the present invention, it is possible to more securely fix the sensor chip and the magnetic body, and it is possible to reduce the height of the magnetic sensor.

FIG. 1 is a schematic perspective view showing an appearance of a magnetic sensor 10A according to a preferred first embodiment of the present invention. FIG. 2 is a circuit diagram of a magnetic field detection apparatus using the magnetic sensor 10A. FIG. 3 is a schematic perspective view showing the appearance of a magnetic sensor 10B according to a preferred second embodiment of the present invention. FIG. 4 is a diagram illustrating an example in which the first magnetic body 41 and the second magnetic body 42 are integrated. FIG. 5 is a schematic perspective view showing the appearance of a magnetic sensor 10C according to a preferred third embodiment of the present invention. FIG. 6 is a schematic perspective view showing the appearance of a magnetic sensor 10D according to a preferred fourth embodiment of the present invention. FIG. 7 is a schematic perspective view showing the appearance of a magnetic sensor 10E according to a preferred fifth embodiment of the present invention. FIG. 8 is a circuit diagram of a magnetic field detection apparatus using the magnetic sensor 10E. FIG. 9 is a schematic perspective view showing the appearance of a magnetic sensor 10F according to a preferred sixth embodiment of the present invention. FIG. 10 is a schematic perspective view showing the appearance of a magnetic sensor 10G according to a preferred seventh embodiment of the present invention. FIG. 11 is a schematic perspective view showing the appearance of a magnetic sensor 10H according to a preferred eighth embodiment of the present invention. FIG. 12 is a schematic perspective view showing the appearance of a magnetic sensor 10I according to a ninth preferred embodiment of the present invention. FIG. 13 is a circuit diagram of a magnetic field detection apparatus using the magnetic sensor 10I. FIG. 14 is a schematic perspective view showing the appearance of a magnetic sensor 10J according to a preferred tenth embodiment of the present invention. FIG. 15 is a schematic perspective view showing the appearance of a magnetic sensor 10K according to an eleventh preferred embodiment of the present invention. FIG. 16 is a schematic perspective view showing the appearance of a magnetic sensor 10L according to a preferred twelfth embodiment of the present invention.

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

FIG. 1 is a schematic perspective view showing an appearance of a magnetic sensor 10A according to a preferred first embodiment of the present invention.

As shown in FIG. 1, a magnetic sensor 10A according to the present invention includes a circuit board 20, a sensor chip 30 mounted on a mounting surface 21 of the circuit board 20, and a first magnetic body 41.

The circuit board 20 is a board in which a wiring pattern is formed on an insulating base such as a resin, and a general printed board or an interposer board can be used. The mounting surface 21 of the circuit board 20 forms an xy plane, and the sensor chip 30 and the first magnetic body 41 are mounted on the mounting surface 21. A land pattern for establishing electrical connection with the sensor chip 30 is provided on the mounting surface 21 of the circuit board 20, but is not illustrated in FIG. 1. A constant voltage source 51, an operational amplifier 52, a fixed resistor 53, a voltage detection circuit 54, and the like shown in FIG. 2 are connected to the land pattern. The constant voltage source 51, the operational amplifier 52, the fixed resistor 53, and the voltage detection circuit 54 may be provided on the circuit board 20 itself, or may be provided on a board different from the circuit board 20.

The sensor chip 30 has a substantially rectangular parallelepiped shape, and a magnetic detection element MR is formed on the element forming surface 31. As shown in FIG. 1, the element formation surface 31 forms an xy plane. That is, the sensor chip 30 is mounted in a flat position so that the element formation surface 31 is substantially parallel to the mounting surface 21 of the circuit board 20.

The magnetic detection element MR is not particularly limited as long as it has an element whose physical characteristics change depending on the magnetic flux density. In the present embodiment, a magnetoresistive element whose resistance value changes according to the direction of the input magnetic field is used. . The magnetization fixing direction of the magnetic detection element MR is set to the direction indicated by the arrow A in FIG. 1 (minus side in the x direction). A large number of sensor chips 30 are manufactured simultaneously using a collective substrate, and a large number of sensor chips 30 are obtained by dicing them. Accordingly, the four side surfaces 32 formed by dicing are substantially perpendicular to the element formation surface 31.

The first magnetic body 41 is a block made of a high magnetic permeability material such as ferrite, and has a substantially rectangular parallelepiped shape in this embodiment. In the present embodiment, the first magnetic body 41 is provided not on the element forming surface 31 of the sensor chip 30 but on the one side surface 32. More specifically, they are fixed to each other so that the yz surface of the sensor chip 30 and the yz surface of the first magnetic body 41 face each other. Here, the length in the y direction of the sensor chip 30 and the length in the y direction of the first magnetic body 41 may be the same or may be different from each other. Further, the height of the sensor chip 30 in the z direction and the height of the first magnetic body 41 in the z direction may be the same or different from each other. However, the height of the first magnetic body 41 in the z direction is preferably equal to or less than the height of the sensor chip 30 in the z direction.

The sensor chip 30 and the first magnetic body 41 can be fixed using an adhesive. In this case, since the magnetic detection element MR is not provided on the side surface 32 of the sensor chip 30, the first magnetic body 41 can be fixed so as to cover almost the entire side surface 32, thereby fixing the both. Can be performed more reliably. Furthermore, if an adhesive is applied between the circuit board 20 and the first magnetic body 41, the first magnetic body 41 is fixed to both the circuit board 20 and the sensor chip 30. The magnetic body 41 is fixed more firmly.

Thus, in the magnetic sensor 10A according to the present embodiment, the sensor chip 30 is placed flat on the circuit board 20, and the first magnetic body 41 is provided on the side surface 32 of the sensor chip 30. As a result, a sufficient bonding area between the sensor chip 30 and the first magnetic body 41 can be secured, so that the sensor chip 30 and the first magnetic body 41 can be more reliably fixed. In addition, the height in the z direction can be further reduced as compared with a conventional magnetic sensor.

FIG. 2 is a circuit diagram of a magnetic field detection apparatus using the magnetic sensor 10A.

2 includes a constant voltage source 51, an operational amplifier 52, a fixed resistor 53, and a voltage detection circuit 54 connected to the magnetic sensor 10A. As shown in FIG. 2, the magnetic detection element MR and the fixed resistor 53 included in the magnetic sensor 10 </ b> A are connected in series between the output terminal of the operational amplifier 52 and the ground, and the connection point is the inversion of the operational amplifier 52. It is connected to the input terminal (-). A predetermined input voltage is applied to the non-inverting input terminal (+) of the operational amplifier 52 by the constant voltage source 51.

With this configuration, the constant voltage source 51, the operational amplifier 52, and the fixed resistor 53 function as a constant current source. Therefore, when the resistance value of the magnetic detection element MR changes, the voltage across the magnetic detection element MR changes. This change is detected by the voltage detection circuit 54. Thereby, the magnetic field detection device shown in FIG. 2 can detect the magnetic field applied to the magnetic detection element MR. In the present embodiment, the magnetic flux is collected by the first magnetic body 41 provided on the side surface 32 of the sensor chip 30, so that the detection sensitivity is increased.

FIG. 3 is a schematic perspective view showing an appearance of a magnetic sensor 10B according to a preferred second embodiment of the present invention.

3 is different from the magnetic sensor 10A shown in FIG. 1 in that a second magnetic body 42 is further provided on the element forming surface 31 of the sensor chip 30. The magnetic sensor 10B shown in FIG. Since the other points are the same as those of the magnetic sensor 10A shown in FIG. 1, the same elements are denoted by the same reference numerals, and redundant description is omitted.

The second magnetic body 42 is a rod-shaped body whose longitudinal direction is the y direction, and is provided on the element forming surface 31 of the sensor chip 30 and in the vicinity of the side surface 32 on which the first magnetic body 41 is provided. . Although it is not necessary for the first magnetic body 41 and the second magnetic body 42 to be in contact with each other, it is preferable that they are as close as possible. The second magnetic body 42 may be made of the same material as the first magnetic body 41, or may be made of a different material. Since the second magnetic body is smaller in size than the first magnetic body 41, a thick film process or a thin film is used instead of bonding a member made of the same material as the first magnetic body 41 (for example, a ferrite block). You may form directly on the element formation surface 31 of the sensor chip 30 using a process. Further, the first magnetic body 41 and the second magnetic body do not need to be separate members, and both may be integrated as shown in FIG.

With this configuration, the magnetic sensor 10B according to the present embodiment can bend the magnetic flux in the z direction collected by the first magnetic body 41 in the x direction by the second magnetic body 42. Thereby, since the magnetic flux component in the sensitivity direction (x direction) of the magnetic detection element MR increases, it becomes possible to obtain a higher detection sensitivity than the magnetic sensor 10A according to the first embodiment.

FIG. 5 is a schematic perspective view showing the appearance of a magnetic sensor 10C according to a preferred third embodiment of the present invention.

The magnetic sensor 10C shown in FIG. 5 is different from the magnetic sensor 10A shown in FIG. 1 in that the sensor chip 30 and the first magnetic body 41 are mounted on the circuit board 20 in a state rotated by 90 °. Since the other points are the same as those of the magnetic sensor 10A shown in FIG. 1, the same elements are denoted by the same reference numerals, and redundant description is omitted.

In the present embodiment, since the sensor chip 30 and the first magnetic body 41 are rotated by 90 °, the element formation surface 31 of the sensor chip 30 forms a yz plane, and the magnetization fixed direction (arrow) of the magnetic detection element MR A) is set on the negative side in the z direction. Thus, in the present embodiment, the diced sensor chip 30 is mounted on the circuit board 20 in a state where it is laid sideways by 90 °.

The first magnetic body 41 is provided on the xy plane that is the side surface 32 of the sensor chip 30. In the example shown in FIG. 5, the first magnetic body 41 is provided on the upper side of the sensor chip 30, but the first magnetic body 41 is provided on the lower side of the sensor chip 30, that is, between the circuit board 20 and the sensor chip 30. The body 41 may be arranged.

The magnetic sensor 10 </ b> C according to the present embodiment can achieve the same low profile as the magnetic sensor 10 </ b> A according to the first embodiment if the height in the z direction is lowered by dicing the sensor chip 30 smaller. It becomes.

FIG. 6 is a schematic perspective view showing the appearance of a magnetic sensor 10D according to a preferred fourth embodiment of the present invention.

6 differs from the magnetic sensor 10C shown in FIG. 5 in that a second magnetic body 42 is further provided on the element forming surface 31 of the sensor chip 30. The magnetic sensor 10D shown in FIG. Since the other points are the same as those of the magnetic sensor 10C shown in FIG. 5, the same elements are denoted by the same reference numerals, and redundant description is omitted.

The magnetic sensor 10D according to the present embodiment can bend the magnetic flux in the x direction collected by the first magnetic body 41 in the z direction by the second magnetic body 42. Thereby, since the magnetic flux component in the sensitivity direction (z direction) of the magnetic detection element MR is increased, it is possible to obtain a detection sensitivity higher than that of the magnetic sensor 10C according to the third embodiment.

FIG. 7 is a schematic perspective view showing the appearance of a magnetic sensor 10E according to a preferred fifth embodiment of the present invention.

7 differs from the magnetic sensor 10A shown in FIG. 1 in that two magnetic detection elements MR1 and MR2 are provided on the element forming surface 31 of the sensor chip 30. The magnetic sensor 10E shown in FIG. Since the other points are the same as those of the magnetic sensor 10A shown in FIG. 1, the same elements are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 7, the magnetic detection elements MR1 and MR2 are arranged side by side in the x direction, and the magnetization fixed direction is aligned in the direction indicated by the arrow A (minus side in the x direction). The magnetic detection element MR1 is arranged close to the first magnetic body 41, and the magnetic detection element MR2 is arranged far from the first magnetic body 41.

With this configuration, the resistance change amounts of the magnetic detection elements MR1 and MR2 are substantially the same for the magnetic flux in the x direction, but the distance from the first magnetic body 41 is different for the magnetic flux in the z direction. A difference occurs in the resistance change amount of the magnetic detection elements MR1 and MR2. Therefore, by detecting this difference, it is possible to selectively detect the magnetic flux in the z direction.

FIG. 8 is a circuit diagram of a magnetic field detection apparatus using the magnetic sensor 10E.

The magnetic field detection apparatus shown in FIG. 8 is different from the magnetic field detection apparatus shown in FIG. 2 in that the fixed resistor 53 shown in FIG. 2 is replaced with a magnetic detection element MR2. The magnetic field detection device shown in FIG. 8 can use the magnetic detection element MR2 as a fixed resistance that has little sensitivity to the magnetic flux in the z direction. Thereby, the constant voltage source 51, the operational amplifier 52, and the magnetic detection element MR2 function as a constant current source. Therefore, when the resistance value of the magnetic detection element MR1 changes, the voltage across the magnetic detection element MR1 changes. This change is detected by the voltage detection circuit 54. Accordingly, the magnetic field detection device shown in FIG. 8 can detect the magnetic field applied to the magnetic detection element MR1. Further, since the magnetic detection element MR2 functions as a fixed resistance, it is not necessary to separately provide a fixed resistance in the magnetic field detection device.

9 to 11 are schematic perspective views showing the external appearances of the magnetic sensors 10F to 10H according to preferred sixth to eighth embodiments of the present invention, respectively.

A magnetic sensor 10F according to the sixth embodiment shown in FIG. 9 is obtained by adding a second magnetic body 42 to the magnetic sensor 10E, and the significance thereof is as described with reference to FIG. Further, the magnetic sensor 10G according to the seventh embodiment shown in FIG. 10 is obtained by rotating the sensor chip 30 and the first magnetic body 41 of the magnetic sensor 10E by 90 °, and the significance thereof is described with reference to FIG. As explained. Furthermore, in the magnetic sensor 10H according to the eighth embodiment shown in FIG. 11, the second magnetic body 42 is added to the magnetic sensor 10E, and the sensor chip 30 and the first magnetic body 41 are rotated by 90 °. The significance of this is as described with reference to FIG.

FIG. 12 is a schematic perspective view showing the external appearance of a magnetic sensor 10I according to a ninth preferred embodiment of the present invention.

12 differs from the magnetic sensor 10E shown in FIG. 7 in that four magnetic detection elements MR1 to MR4 are provided on the element formation surface 31 of the sensor chip 30. The magnetic sensor 10I shown in FIG. Since the other points are the same as those of the magnetic sensor 10E shown in FIG. 7, the same reference numerals are given to the same elements, and duplicate descriptions are omitted.

As shown in FIG. 12, in the magnetic detection elements MR1 to MR4, the magnetization fixed directions are all aligned in the direction indicated by the arrow A (minus side in the x direction). The magnetic detection element MR1 and the magnetic detection element MR2 are arranged side by side in the x direction, and the magnetic detection element MR3 and the magnetic detection element MR4 are arranged side by side in the x direction. The magnetic detection elements MR1 and MR3 are disposed close to the first magnetic body 41, and the magnetic detection elements MR2 and MR4 are disposed distant from the first magnetic body 41. Here, the distances from the first magnetic body 41 are equal to each other in the magnetic detection elements MR1 and MR3, and are equal to each other in the magnetic detection elements MR2 and MR4.

With this configuration, the resistance change amounts of the magnetic detection elements MR1 to MR4 are substantially the same for the magnetic flux in the x direction, but the distance from the first magnetic body 41 is different for the magnetic flux in the z direction. A difference occurs in the resistance change amounts of the magnetic detection elements MR1 and MR2, and a difference occurs in the resistance change amount of the magnetic detection elements MR3 and MR4. And the difference is equal to each other. Therefore, by detecting these differences, it is possible to selectively detect the magnetic flux in the z direction.

FIG. 13 is a circuit diagram of a magnetic field detection apparatus using the magnetic sensor 10I.

In the magnetic field detection apparatus shown in FIG. 13, four magnetic detection elements MR1 to MR4 form a bridge circuit. That is, the magnetic detection element MR1 is connected between the terminals E1 and E3, the magnetic detection element MR2 is connected between the terminals E2 and E3, the magnetic detection element MR3 is connected between the terminals E2 and E4, and the magnetic detection element MR4 is connected to the terminal. Connected between E1 and E4. A predetermined voltage is applied by the constant voltage source 51 between the terminals E1 and E2. Further, a voltage detection circuit 54 is connected between the terminals E3 and E4, whereby the level of the output voltage appearing between the terminals E3 and E4 is detected.

As shown in FIG. 13, since the connection order of the magnetic detection elements MR1 and MR2 and the connection order of the magnetic detection elements MR3 and MR4 are opposite to each other, the magnetic detection elements MR1 to MR4 are differential bridge circuits. Configure. As a result, the change in electrical resistance of the magnetic detection elements MR1 to MR4 according to the magnetic flux density is amplified by a factor of 2, so that detection with higher sensitivity can be performed.

14 to 16 are schematic perspective views showing the external appearances of the magnetic sensors 10J to 10L according to the tenth to twelfth preferred embodiments of the present invention, respectively.

A magnetic sensor 10J according to the tenth embodiment shown in FIG. 14 is obtained by adding a second magnetic body 42 to the magnetic sensor 10I, and the significance thereof is as described with reference to FIG. Further, the magnetic sensor 10K according to the eleventh embodiment shown in FIG. 15 is obtained by rotating the sensor chip 30 and the first magnetic body 41 of the magnetic sensor 10I by 90 °, and the significance thereof is described with reference to FIG. As explained. Further, the magnetic sensor 10L according to the twelfth embodiment shown in FIG. 16 is obtained by adding the second magnetic body 42 to the magnetic sensor 10I and rotating the sensor chip 30 and the first magnetic body 41 by 90 °. The significance of this is as described with reference to FIG.

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 to 10L Magnetic sensor 20 Circuit board 21 Mounting surface 30 Sensor chip 31 Element formation surface 32 Side surface 41 First magnetic body 42 Second magnetic body 51 Constant voltage source 52 Operational amplifier 53 Fixed resistor 54 Voltage detection circuit E1 to E4 Terminal MR , MR1 to MR4 Magnetic sensing elements

Claims (6)

A sensor chip having an element formation surface on which at least one magnetic detection element is formed and a side surface substantially perpendicular to the element formation surface;
And a first magnetic body provided on the side surface of the sensor chip. The magnetic sensor according to claim 1, further comprising a second magnetic body provided on the element forming surface of the sensor chip and in the vicinity of the side surface. The magnetic detection element includes first and second magnetic detection elements,
The magnetic sensor according to claim 1, wherein the first and second magnetic detection elements have different distances from the side surface. The magnetic detection element includes a third magnetic detection element having a distance from the side surface equal to the first magnetic detection element, and a fourth magnetic detection element having a distance from the side surface equal to the second magnetic detection element. The magnetic sensor according to claim 3, further comprising: A circuit board having a mounting surface on which the sensor chip is mounted;
5. The magnetic sensor according to claim 1, wherein the element formation surface of the sensor chip is substantially parallel to the mounting surface of the circuit board. A circuit board having a mounting surface on which the sensor chip is mounted;
5. The magnetic sensor according to claim 1, wherein the element formation surface of the sensor chip is substantially perpendicular to the mounting surface of the circuit board.

Images