Magnetic sensor

Abstract

To provide a magnetic sensor with a structure for storing a magnetic sensor module in a housing, the sensor capable of preventing a magneto-sensitive element from being damaged in assembly.SOLUTION: A magnetic sensor S comprises housings 2, 3, a magnetic sensor module 1 stored in the housings 2, 3, and an insulative dummy substrate 4. The magnetic sensor module 1 includes: an insulative substrate 10; a sensor chip 100 mounted on a top face 11 of the substrate 10; a terminal electrode 72 provided on the top face 11 of the substrate 10; a wiring pattern 82 provided on a bottom face 12 of the substrate 10; a through hole conductor V12 provided through the substrate 10 and connecting one end of the wiring pattern 82 to the terminal electrode 72; and a through hole conductor V32 provided through the substrate 10 and connecting the other end of the wiring pattern 82 to the sensor chip 100. The dummy substrate 4 is arranged between inner walls of the housings 2, 3 and the bottom face 12 of the substrate 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a magnetic sensor, and more particularly to a magnetic sensor having a structure in which a magnetic sensor module is housed in a housing. [Background technology]

[0002] Patent Document 1 discloses a magnetic sensor having a structure in which a magnetic sensor module is housed in a housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 145064 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of magnetic sensor, when assembling the magnetic sensor module into a housing, external static electricity may be transmitted to the sensor chip mounted on the magnetic sensor module, potentially destroying the magnetic sensing element on the sensor chip.

[0005] This disclosure describes a technique for preventing damage to a magnetic sensing element during assembly in a magnetic sensor having a structure in which a magnetic sensor module is housed in a housing. [Means for solving the problem]

[0006] A magnetic sensor according to one aspect of the present disclosure comprises a housing, a magnetic sensor module housed in the housing, and an insulating dummy substrate, wherein the magnetic sensor module has an insulating substrate having an upper surface and a lower surface, a sensor chip mounted on the upper surface of the substrate, terminal electrodes provided on the upper surface of the substrate, a wiring pattern provided on the lower surface of the substrate, a first through-hole conductor that penetrates the substrate and connects one end of the wiring pattern to the terminal electrode, and a second through-hole conductor that penetrates the substrate and connects the other end of the wiring pattern to the sensor chip, and the dummy substrate is disposed between the inner wall of the housing and the lower surface of the substrate. [Effects of the Invention]

[0007] The present disclosure provides a technique for preventing damage to a magnetic sensing element during assembly in a magnetic sensor having a structure in which a magnetic sensor module is housed in a housing. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view showing the appearance of a magnetic sensor S according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic exploded perspective view of the magnetic sensor S. [Figure 3] FIG. 3 is a schematic perspective view showing the appearance of the magnetic sensor module 1 and the dummy substrate 4. As shown in FIG. [Figure 4] FIG. 4 is a schematic exploded perspective view of the magnetic sensor module 1 and the dummy substrate 4. As shown in FIG. [Figure 5] FIG. 5 is a plan view for explaining the structure of the substrate 10 in more detail. [Figure 6] FIG. 6 is a schematic perspective view of the sensor chip 100. As shown in FIG. [Figure 7] FIG. 7 is a schematic plan view of the sensor chip 100. As shown in FIG. [Figure 8] FIG. 8 is a schematic cross-sectional view taken along line AA in FIG. [Figure 9] FIG. 9 is a circuit diagram of the magnetic sensor module 1. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the technology according to the present disclosure will be described in detail with reference to the accompanying drawings.

[0010] Fig. 1 is a schematic perspective view showing the appearance of a magnetic sensor S according to an embodiment of the present disclosure, and Fig. 2 is a schematic exploded perspective view of the magnetic sensor S.

[0011] As shown in FIGS. 1 and 2, the magnetic sensor S according to this embodiment includes a magnetic sensor module 1, which is a main body, housings 2 and 3 that house the magnetic sensor module 1, and a dummy substrate 4. The housings 2 and 3 constitute a lower case and an upper case, respectively, and are made of a composite material, for example, polycarbonate or other insulating material with added conductive material such as carbon fiber. The housings 2 and 3 are fitted together in the Y direction to form an internal space in which the magnetic sensor module 1 and dummy substrate 4 are housed. The magnetic sensor S is a rod-shaped body with its longitudinal direction in the Z direction, and its end on the +Z direction side constitutes the sensor head. A wire (not shown) connected to the magnetic sensor module 1 extends from its end on the -Z direction side. If the housings 2 and 3 are made of such a composite material, the housings 2 and 3 themselves have slight conductivity, making it difficult for static electricity to accumulate inside the housings 2 and 3.

[0012] 3 is a schematic perspective view showing the appearance of the magnetic sensor module 1 and the dummy substrate 4. FIG.

[0013] 3, the magnetic sensor module 1 includes a substrate 10 made of an insulating material, and a sensor chip 100, magnetic collectors 30 and 40, an auxiliary chip 50, and a molded member 60 mounted on an upper surface 11 that forms the XZ plane of the substrate 10. In Fig. 4, the sensor chip 100 and the auxiliary chip 50 are omitted, and instead, a mounting area 100A of the sensor chip 100 is indicated by a dashed line.

[0014] The magnetic collectors 30 and 40 are rod-shaped bodies with their longitudinal direction in the Z direction for collecting magnetic flux to the sensor chip 100, and are both made of a highly permeable material such as ferrite. The sensor chip 100 is disposed between the magnetic collectors 30 and 40, which selectively collects the magnetic field in the Z direction and applies the collected magnetic field to the sensor chip 100. The magnetic collector 40 has a main body 41 with its longitudinal direction in the Z direction and a pair of overhanging portions 42 and 43 that protrude from the end of the main body 41 and form an XY plane.

[0015] A compensation coil C1 may be wound around the magnetic flux collector 30 via a molded member 60. The coil axis direction of the compensation coil C1 is the Z direction. The molded member 60 is made of a non-magnetic insulating material such as resin and is fixed to the magnetic flux collector 30 using an adhesive or the like. U-shaped pins P1 and P2 are held by the molded member 60. One end of the compensation coil C1 is fixed to one end of the pin P1, and the other end of the compensation coil C1 is fixed to one end of the pin P2. The compensation coil C1 is optional, and in the example shown in Figures 3 and 4, the other ends of the pins P1 and P2 are open. When the compensation coil C1 is used, a compensation current can be passed through the compensation coil C1 by connecting wires to the other ends of the pins P1 and P2.

[0016] The lower surface 12 of the substrate 10, which constitutes the XZ plane, is covered with a dummy substrate 4 made of an insulating material. That is, the dummy substrate 4 is disposed between the inner wall of the housing 2 that constitutes the lower case and the lower surface 12 of the substrate 10. The dummy substrate 4 may be made of the same insulating material as the substrate 10, or may be made of a different insulating material. If the same insulating material is used for the dummy substrate 4 and the substrate 10, it is possible to reduce material costs. Furthermore, the XZ plane shapes of the dummy substrate 4 and the substrate 10 may be the same or different from each other. If the XZ plane shapes of the dummy substrate 4 and the substrate 10 are the same, processing costs are reduced.

[0017] Figure 5 is a plan view for explaining the structure of substrate 10 in more detail, where (a) shows the upper surface 11 of substrate 10 as viewed from the +Y direction, and (b) shows the lower surface 12 of substrate 10 as viewed through substrate 10 from the +Y direction.

[0018] 5, terminal electrodes 71 to 76 are provided on the upper surface 11 of the substrate 10. Of these, the terminal electrodes 71, 75, and 76 are connected to one ends of wiring patterns 81, 85, and 86, respectively, provided on the upper surface 11 of the substrate 10. The other ends of the wiring patterns 81, 85, and 86 are connected to one ends of wiring patterns 91, 95, and 96, respectively, provided on the lower surface 12 of the substrate 10, via through-hole conductors V21, V25, and V26, respectively, provided to penetrate the substrate 10. The other ends of the wiring patterns 91, 95, and 96 are connected to one ends of wiring patterns 21, 25, and 26, respectively, provided on the upper surface 11 of the substrate 10, via through-hole conductors V31, V35, and V36, respectively, provided to penetrate the substrate 10.

[0019] On the other hand, the terminal electrodes 72 to 74 are connected to one ends of wiring patterns 82 to 84 provided on the lower surface 12 of the substrate 10 via through-hole conductors V12 to V14 that respectively penetrate the substrate 10. The other ends of the wiring patterns 82 to 84 are connected to one ends of wiring patterns 22 to 24 that are provided on the upper surface 11 of the substrate 10 via through-hole conductors V32 to V34 that respectively penetrate the substrate 10. The other ends of the wiring patterns 21 to 26 are connected to the sensor chip 100.

[0020] Here, the wiring patterns 21 to 26, 81 to 86, 91, 95, and 96 provided on the upper surface 11 and the lower surface 12 of the substrate 10 are all covered with an insulating member such as solder resist. In contrast, the ends of the through-hole conductors V12 to V14, V21, V25, V26, and V31 to V36 are not covered with an insulating member such as solder resist and are exposed to the outside.

[0021] FIG. 6 is a schematic perspective view of the sensor chip 100. As shown in FIG.

[0022] 6, the sensor chip 100 has an element formation surface 101 and a back surface 102 that are located opposite each other and form an XY plane, side surfaces 103 and 104 that are located opposite each other and form a YZ plane, and side surfaces 105 and 106 that are located opposite each other and form an XZ plane. A magnetic sensing element and magnetic layers M1 to M3, which will be described later, are formed on the element formation surface 101 of the sensor chip 100. The back surface 102 of the sensor chip 100 is covered with an auxiliary chip 50, which increases the mechanical strength of the sensor chip 100.

[0023] FIG. 7 is a schematic plan view of the sensor chip 100, and FIG. 8 is a schematic cross-sectional view taken along line AA in FIG.

[0024] As shown in FIGS. 7 and 8, four magnetically sensitive elements R1 to R4 are formed on the element forming surface 101 of the sensor chip 100. The magnetically sensitive elements R1 to R4 are not particularly limited as long as they are elements whose electrical resistance changes depending on the direction of magnetic flux, and for example, MR elements can be used. The fixed magnetization directions of the magnetically sensitive elements R1 to R4 are aligned in the same direction (for example, the positive side in the X direction). The magnetically sensitive elements R1 to R4 are provided on the surface of an insulating layer 107 that covers the element forming surface 101. The magnetically sensitive elements R1 to R4 are covered with an insulating layer 108, and magnetic layers M1 to M3 made of permalloy or the like are formed on the surface of the insulating layer 108. The magnetic layers M1 to M3 are covered with an insulating layer 109. The magnetic layer M1 is disposed approximately in the center of the element forming surface 101 in the X direction. The magnetic layers M2 and M3 are disposed on both sides of the element forming surface 101 in the X direction so as to sandwich the magnetic layer M1 in the X direction.

[0025] The magnetic layers M1 and M2 form two gaps G1 and G2 that extend in the Y direction and have the X direction as their width direction. The positions of the gaps G1 and G2 in the X direction coincide with each other, and they are aligned in the Y direction. The magnetic layers M1 and M3 form two gaps G3 and G4 that extend in the Y direction and have the X direction as their width direction. The positions of the gaps G3 and G4 in the X direction coincide with each other, and they are aligned in the Y direction. Furthermore, the gaps G1 and G3 are aligned in the X direction, and the gaps G2 and G4 are aligned in the X direction. The magnetic sensing elements R1 to R4 are positioned so as to overlap with the gaps G1 to G4, respectively, in a plan view seen from the Z direction. As a result, the magnetic field in the X direction passing through the magnetic gaps G1 to G4 is applied to the magnetic sensing elements R1 to R4, respectively.

[0026] 7 and 8, the region indicated by reference numeral 30a indicates a region covered from the Z direction by the XY plane located at one end of the magnetic collector 30 in the Z direction, and the regions indicated by reference numerals 42a and 43a indicate regions covered from the Z direction by the overhanging portions 42 and 43 of the magnetic collector 40. Furthermore, terminal electrodes 111 to 116 are provided on the element forming surface 101 of the sensor chip 100 in regions not covered by the magnetic collectors 30 and 40. The terminal electrodes 111 to 116 are connected to the wiring patterns 21 to 26 shown in FIG. 5(a), respectively.

[0027] The regions 30a, 42a, and 43a overlap the magnetic layers M1 to M3, respectively. As a result, the magnetic layer M1 is covered from the Z direction by the magnetic collector 30, the magnetic layer M2 is covered from the Z direction by the overhanging portion 42 of the magnetic collector 40, and the magnetic layer M3 is covered from the Z direction by the overhanging portion 43 of the magnetic collector 40. The magnetic field in the Z direction, which is the magnetic field to be detected, is collected by the magnetic collector 30 and applied to the magnetic layer M1 via the magnetic collector 30. The magnetic field applied to the magnetic layer M1 is bent in the +X direction and the −X direction by the magnetic layer M1. The magnetic flux component bent in the −X direction by the magnetic layer M1 is supplied to the magnetic layer M2 via the gaps G1 and G2 and then flows to the main body portion 41 via the overhanging portion 42 of the magnetic collector 40. At this time, part of the magnetic flux passing through the gaps G1 and G2 in the −X direction is applied to the magnetic sensing elements R1 and R2. On the other hand, the magnetic flux component bent in the +X direction in magnetic layer M1 is supplied to magnetic layer M3 through gaps G3 and G4, and then flows to main body 41 through overhanging portion 43 of magnetic collector 40. At this time, part of the magnetic flux passing through gaps G3 and G4 in the +X direction is applied to magnetic sensing elements R3 and R4.

[0028] 6 and 8, a compensation coil C2 is provided on the sensor chip 100. The compensation coil C2 is provided, for example, at a position overlapping with the magnetic sensing elements R1 to R4, and when a compensation current flows through the compensation coil C2, a canceling magnetic field is applied to the magnetic sensing elements R1 to R4. In the example shown in Fig. 8, the compensation coil C2 is provided on the element forming surface 101.

[0029] FIG. 9 is a circuit diagram of the magnetic sensor module 1. As shown in FIG.

[0030] As shown in Fig. 9, the magnetic sensing elements R1 to R4 are bridge-connected between a terminal electrode 71 supplied with a power supply Vcc and a terminal electrode 72 grounded to ground GND. That is, the magnetic sensing elements R1 and R4 are connected in series between the power supply Vcc and ground GND, and the magnetic sensing elements R3 and R2 are connected in series between the power supply Vcc and ground GND. The connection point between the magnetic sensing elements R2 and R3 is connected to a terminal electrode 73, and the connection point between the magnetic sensing elements R1 and R4 is connected to a terminal electrode 74. The potential difference between the potential Va appearing at the terminal electrode 73 and the potential Vb appearing at the terminal electrode 74 is used as the output signal ΔV (= Va - Vb). In this way, the magnetic sensing elements R1 to R4 form a differential bridge circuit, and the change in the electrical resistance of the magnetic sensing elements R1 to R4 according to the magnetic flux density appears as the level of the output signal ΔV.

[0031] The output signal ΔV is commonly supplied to the operational amplifier 121. The compensation current i output from the operational amplifier 121 is supplied to the terminal electrode 75. The terminal electrode 75 is connected to one end of the compensation coil C2, and the terminal electrode 76 is connected to the other end of the compensation coil C2. As a result, the compensation current i output from the operational amplifier 121 is supplied to the compensation coil C2. The compensation coil C2 is integrated into the sensor chip 100, as shown in FIGS. 6 and 8. When the compensation current i output from the operational amplifier 121 flows through the compensation coil C2, a canceling magnetic field is generated. As a result, when an output signal ΔV corresponding to the magnetic flux density of the magnetic field to be detected is generated, a corresponding compensation current i flows through the compensation coil C2, generating a canceling magnetic field in the opposite direction, and the magnetic field to be detected applied to the magnetic sensing elements R1 to R4 is canceled on the sensor chip 100. Then, the compensation current i is converted into a voltage by the resistor 122 to generate an output signal Vout, making it possible to detect the strength of the magnetic field to be detected.

[0032] 3 and 4 may be used instead of using the compensation coil C2 integrated in the sensor chip 100. In this case, both ends of the compensation coil C1 are connected to the terminal electrodes 75 and 76.

[0033] In the magnetic sensor S according to this embodiment, as described above, the dummy substrate 4 made of an insulating material is disposed between the lower surface 12 of the substrate 10 included in the magnetic sensor module 1 and the housing 2 constituting the lower case. As a result, even if the ends of the through-hole conductors V12 to V14, V21, V25, V26, and V31 to V36 are exposed on the lower surface 12 of the substrate 10, these do not come into contact with the housing 2. Therefore, when assembling the magnetic sensor module 1 into the housings 2 and 3, external static electricity is less likely to be transmitted from the housing 2 to the sensor chip 100 via the through-hole conductors V12 to V14, V21, V25, V26, and V31 to V36. In other words, even if static electricity enters from the outside through the housing 2, which has slight conductivity, the static electricity is less likely to be transmitted to the sensor chip 100 because the dummy substrate 4 provides insulation.

[0034] To effectively prevent the conduction of static electricity via the housing 2 and the through-hole conductors V12 to V14, V21, V25, V26, and V31 to V36, the thickness of the dummy substrate 4 should be 0.45 mm or more. This prevents damage to the magnetic sensing elements R1 to R4 even when an air discharge of ±8 kV as specified in the IEC-61326-1 standard is applied to the housing 2. The insulating effect of the dummy substrate 4 increases as the thickness of the dummy substrate 4 increases, but the thickness required for the substrate 10 (e.g., 1.2 mm) is not necessary, so the dummy substrate 4 may be thinner than the substrate 10. This minimizes the increase in thickness of the magnetic sensor module 1 in the Y direction.

[0035] As described above, the magnetic sensor S according to this embodiment has the dummy substrate 4 interposed between the magnetic sensor module 1 and the housing 2, which makes it possible to prevent damage to the magnetic sensing element during assembly.

[0036] The above describes embodiments of the technology according to the present disclosure, but the technology according to the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the gist of the technology, and it goes without saying that these modifications are also included within the scope of the technology according to the present disclosure.

[0037] The technology according to the present disclosure includes, but is not limited to, the following configuration examples.

[0038] A magnetic sensor according to one aspect of the present disclosure includes a housing, a magnetic sensor module housed in the housing, and an insulating dummy substrate, the magnetic sensor module having an insulating substrate with an upper surface and a lower surface, a sensor chip mounted on the upper surface of the substrate, terminal electrodes provided on the upper surface of the substrate, a wiring pattern provided on the lower surface of the substrate, first through-hole conductors that penetrate the substrate and connect one end of the wiring pattern to the terminal electrodes, and second through-hole conductors that penetrate the substrate and connect the other end of the wiring pattern to the sensor chip, the dummy substrate being disposed between an inner wall of the housing and the lower surface of the substrate. This makes it difficult for external static electricity to be transmitted to the sensor chip via the through-hole conductors during assembly to house the magnetic sensor module in the housing.

[0039] In the magnetic sensor, the substrate and the dummy substrate may be made of the same insulating material, which makes it possible to reduce material costs.

[0040] In the magnetic sensor, the substrate and the dummy substrate may have the same planar shape, which makes it possible to reduce processing costs.

[0041] In the magnetic sensor described above, the thickness of the dummy substrate may be 0.45 mm or more, which prevents damage to the sensor chip even if a high voltage discharge occurs during assembly.

[0042] In the magnetic sensor, the thickness of the dummy substrate may be thinner than the thickness of the substrate, which makes it possible to prevent an increase in the thickness of the magnetic sensor module.

[0043] In the magnetic sensor, the housing may be conductive, which makes it difficult for static electricity to accumulate inside the housing. [Explanation of symbols]

[0044] 1 Magnetic Sensor Module 2,3 Case 4 Dummy board 10 Substrate 11 Top of the board 12 Bottom of the board 21~26,81~86,91,95,96 Wiring pattern 30,40 magnetic collector 30a,42a,43a area 41 Main body 42,43 Overhang 50 Auxiliary Chips 60 Molded parts 71~76 Terminal electrode 100 sensor chips 100A mounting area 101 Element formation surface 102 Back side 103~106 Side 107~109 Insulating layer 111~116 Terminal electrode 121 Operational Amplifier 122 Resistance C1, C2 compensation coil G1~G4 Gap M1~M3 Magnetic layer P1, P2 pins R1~R4 magnetic sensing element S magnetic sensor V12~V14, V21, V25, V26, V31~V36 Through-hole conductors i compensation current

Claims

1. The housing and a magnetic sensor module housed in the housing; an insulating dummy substrate; Equipped with The magnetic sensor module includes an insulating substrate having an upper surface and a lower surface, a sensor chip mounted on the upper surface of the substrate, terminal electrodes provided on the upper surface of the substrate, a wiring pattern provided on the lower surface of the substrate, a first through-hole conductor provided to penetrate the substrate and connecting one end of the wiring pattern to the terminal electrode, and a second through-hole conductor provided to penetrate the substrate and connecting the other end of the wiring pattern to the sensor chip, the dummy substrate is disposed between an inner wall of the housing and the lower surface of the substrate; Magnetic sensor.

2. the substrate and the dummy substrate are made of the same insulating material; The magnetic sensor according to claim 1 .

3. the substrate and the dummy substrate have the same planar shape; The magnetic sensor according to claim 1 .

4. The thickness of the dummy substrate is 0.45 mm or more. The magnetic sensor according to claim 1 .

5. The thickness of the dummy substrate is thinner than the thickness of the substrate. The magnetic sensor according to claim 1 .

6. The housing is conductive. The magnetic sensor according to claim 1 .

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