Current detection device

Abstract

An embodiment provides a current detection device that balances bandwidth characteristics and CMRR characteristics, and improves sensitivity. The current detection device of this embodiment includes a conductor, a first magnetic field detection element, a second magnetic field detection element, and a conductive film. The conductor has a first region, a second region, and a third region between the ends of the first and second regions. The first magnetic field detection element is disposed between the first and second regions. The second magnetic field detection element is disposed opposite to the first magnetic field detection element, sandwiching the third region. The conductive film is adhered to the conductor layer, which is disposed between the conductor and the first and second magnetic field detection elements, and has a slit wider than the width of the magnetically sensing portion of the first and second magnetic field detection elements, in a manner that covers the slit.

Description

[0001] This application claims priority to Japanese Patent Application No. 2021-151242 (filed on September 16, 2021). The entire contents of the basic application are incorporated herein by reference. Technical Field

[0002] Embodiments of the present invention relate to a current detection device. Background Technology

[0003] A current detection device allows the current to be detected to flow through a conductor such as a coil, and detects the magnetic field generated by that conductor, thereby detecting the current. The generated magnetic field is detected, for example, by a magnetic field sensor such as a Hall element. To ensure the current detection device operates with high performance and stability, it is known to employ a shielding layer (shielding sheet) between the conductor and the magnetic field sensor.

[0004] However, conventional current sensing devices have difficulty balancing bandwidth characteristics and CMRR (Common Mode Rejection Ratio) characteristics, and high sensitivity design is also challenging. Summary of the Invention

[0005] The embodiment provides a current detection device that can take into account both bandwidth characteristics and CMRR characteristics, and can also improve sensitivity.

[0006] The current detection device of this embodiment includes a conductor, a first magnetic field detection element, a second magnetic field detection element, and a conductive film. The conductor has a first region, a second region, and a third region between the ends of the first and second regions. The first magnetic field detection element is disposed between the first and second regions. The second magnetic field detection element is disposed opposite the first magnetic field detection element, sandwiching the third region. The conductive film is adhered to the conductor layer, which is disposed between the conductor and the first and second magnetic field detection elements, and has a slit wider than the width of the magnetic sensing portion of the first and second magnetic field detection elements, in a manner that covers the slit. Attached Figure Description

[0007] Figure 1 This is an overall structural diagram of the current detection device according to the first embodiment.

[0008] Figure 2 It is along Figure 1 A cross-sectional view of the current detection device for line II-II in the diagram.

[0009] Figure 3 This is a diagram used to illustrate the structure of conductor 30.

[0010] Figure 4This is a diagram used to illustrate the structure of the conductor layer 45 and the vapor-deposited film 40.

[0011] Figure 5 This is a perspective view of a magnetic field sensor.

[0012] Figure 6 This is a diagram illustrating the configuration relationship between conductor 30, conductor layer 45, and magnetic field sensors 10A and 10B.

[0013] Figure 7 This is a cross-sectional view of the current detection device according to the second embodiment. Detailed Implementation

[0014] The embodiments will now be described in detail with reference to the accompanying drawings.

[0015] Furthermore, the accompanying drawings based on the embodiments are schematic diagrams, and the relationships between the thickness and width of each part, the proportions of the thickness of each part, and the relative angles differ from the actual situation. The accompanying drawings include parts with different dimensional relationships and proportions. Additionally, illustrations and labeling of some constituent elements have been omitted.

[0016] (First Implementation)

[0017] Figure 1 This is an overall structural diagram of the current detection device according to the first embodiment. Figure 2 It is along Figure 1 A cross-sectional view of the current detection device for line II-II in the diagram. Figure 3 This is a diagram used to illustrate the structure of conductor 30. Figure 4 This is a diagram used to illustrate the structure of the conductor layer 45 and the vapor-deposited film 40. Figure 5 This is a perspective view of a magnetic field sensor. Figure 6 This is a diagram illustrating the configuration relationship between conductor 30, conductor layer 45, and magnetic field sensors 10A and 10B.

[0018] The current detection device 1 comprises a multilayer wiring board 60 having multiple conductor layers (e.g., 41, 43, 44, 45, 46) and multiple insulating layers (e.g., 42). The multilayer wiring board 60 is connected to a connector 70 that supplies current to the conductor 30. Furthermore, the multilayer wiring board 60 can be a wiring board stacked on a single substrate, or it can be a wiring board formed by bonding multiple substrates together. Moreover, the multilayer wiring board 60 has a rectangular shape, but is not limited to a rectangular shape; for example, it can also be a circular shape or other shapes.

[0019] The current detection device 1 detects the current flowing through the conductor 30. The detected current is either direct current or alternating current. The current detection device 1 of this embodiment is used in control devices for high-frequency switching power supplies, AC / DC adapters, general-purpose inverters or variable speed motor equipment, and overcurrent protection for power modules.

[0020] At least one electronic component 50, such as an IC chip, is mounted on the surface of the conductor layer 41. The electronic component 50 includes, for example, an amplifier circuit that amplifies a voltage signal corresponding to the magnetic field detected by the first magnetic field sensor 10A and / or the second magnetic field sensor 10B. Alternatively, the electronic component 50 may be integrated into the multilayer wiring board 60. Furthermore, in the following description, both the first magnetic field sensor 10A and the second magnetic field sensor 10B will be simply referred to as magnetic field sensor 10.

[0021] Conductor layer 43 is a ground layer, which is connected to conductor layer 41 and conductor layer 44 via contact holes.

[0022] A portion of the conductor layer 46 is composed of a conductor 30 to which current is applied via the connector 70. The conductor 30 is as follows: Figure 3 The diagram, showing a U-shape, includes a first region 30A, a second region 30B, and a third region 30C connecting the ends of the first region 30A and the second region 30B. Connectors 70 for current flow are provided at the ends of the first region 30A and the second region 30B, both of which are generally rectangular. The first region 30A and the second region 30B are positioned opposite each other with a gap G. The interval WG of the gap G is the length of the current path in the third region 30C.

[0023] Conductor layer 45 is the ground layer, such as Figure 4 As shown, there is a slit SL. The slit SL has a sufficient length in the Y direction. Specifically, as... Figure 6 As shown, the length of the slit SL in the Y direction is longer than the length of the gap G in the Y direction. Furthermore, the slit SL has a width larger than the diameter of the magnetic sensing part 11 of the magnetic field sensor 10, and a width smaller than the distance between the two external electrodes 12 that sandwich the magnetic sensing part 11 of the magnetic field sensor 10. By increasing the length of the slit SL in the Y direction, the high-frequency gain of the frequency band characteristics can be reduced, the generation of eddy currents can be suppressed, and the voltage output of the magnetic field sensor 10 can be stabilized.

[0024] Furthermore, a vapor-deposited film 40 is bonded to the conductor layer 45. The vapor-deposited film 40 constitutes a conductive film. That is, the first magnetic field sensor 10A and / or the second magnetic field sensor 10B, or a vapor-deposited film 40 used to shield electrostatic noise from entering the first magnetic field sensor 10A and / or the second magnetic field sensor 10B, is bonded to the conductor layer 45 between the conductor layer 44 where the first magnetic field sensor 10A and the second magnetic field sensor 10B are mounted, in a manner that covers the slit SL. To reduce noise, the vapor-deposited film 40 is necessary, but because it generates eddy currents at high frequencies, it needs to be made extremely thin, for example, with a thickness of tens of nanometers.

[0025] The entire surface of the vapor-deposited film 40 in contact with the conductor layer 45 is bonded with solder. That is, by increasing the contact area between the vapor-deposited film 40 and the conductor layer 45, which serves as a ground layer, the contact resistance between the vapor-deposited film 40 and the conductor layer 45 is reduced. Furthermore, the vapor-deposited film 40 is not limited to being bonded to the conductor layer 45 with solder; for example, it can also be bonded to the conductor layer 45 by compression bonding. The material of the vapor-deposited film 40 is aluminum. However, the material of the vapor-deposited film 40 is not limited to aluminum; for example, any conductive material such as copper can be used.

[0026] The lengths of the vapor-deposited film 40 in the X and Y directions are sufficiently longer than the lengths of the slits SL in the conductor layer 45 in the X and Y directions. This increases the bonding area between the vapor-deposited film 40 and the conductor layer 45, allowing the vapor-deposited film 40 to fully exert its shielding function.

[0027] First and second magnetic field sensors 10A and 10B are mounted on conductor layer 44. The first and second magnetic field sensors 10A and 10B, constituting the first and second magnetic field detection elements, are Hall effect elements that detect the current flowing through conductor 30. Figure 5 As shown, the magnetic field sensor 10 has a lower surface 10SB and an upper surface 10SA opposite to the lower surface 10SB. The lower surface 10SB has four external electrodes 12. A detection current is input to two of the four external electrodes 12, and an output signal (Hall voltage) is output from the other two external electrodes 12.

[0028] The first and second magnetic field sensors 10A and 10B are mounted on the surface of the conductor layer 44 near the conductor 30 (in... Figure 2 (The middle is the lower surface). Therefore, a stronger magnetic field is applied to the first and second magnetic field sensors 10A and 10B than when they are mounted on the upper surface of the conductor layer 44.

[0029] The magnetic sensing part (magnetic sensing area) 11 is a sensor capable of detecting the generated magnetic flux. For example... Figure 6As shown, the magnetic sensing part 11 of the first magnetic field sensor 10A is disposed on the gap G between the first region 30A and the second region 30B. The magnetic sensing part 11 of the second magnetic field sensor 10B is disposed on the outer periphery of the third region 30C. That is, when viewed from a direction parallel to the stacking direction of the conductor 30 and the first magnetic field sensor 10A, or the stacking direction of the conductor 30 and the second magnetic field sensor 10B, the magnetic sensing part 11 of the magnetic field sensors 10 (10A, 10B) does not overlap with the conductor 30.

[0030] In this configuration, the magnetic field detected by the second magnetic field sensor 10B is smaller than the magnetic field detected by the first magnetic field sensor 10A. Therefore, the voltage signal corresponding to the magnetic field detected by the second magnetic field sensor 10B is amplified by the amplification circuit included in the electronic component 50.

[0031] Furthermore, in order to enable the first magnetic field sensor 10A to detect magnetic fields with even higher sensitivity, it is preferable that the interval WG between the first region 30A and the second region 30B is approximately the same as the size (outer diameter) of the magnetic sensing part 11. For example, it is preferable that the interval WG is more than 90% and less than 120% of the size of the magnetic sensing part 11.

[0032] As described above, the current detection device 1 has a slit SL provided in the conductor layer 45, which serves as a ground layer, between the conductor layer 44 on which the first and second magnetic field sensors 10A and 10B are mounted and the conductor layer 46 constituting the conductor 30. An extremely thin vapor-deposited film 40 for noise reduction is bonded to the conductor layer 45 to cover the slit SL. Thus, the current detection device 1 balances bandwidth characteristics and CMRR characteristics, and improves sensitivity.

[0033] (Second Implementation)

[0034] The second embodiment will now be described.

[0035] The first embodiment has a structure in which magnetic field sensors 10A and 10B are installed inside the multilayer wiring board 60, while the second embodiment has magnetic field sensors 10A and 10B installed on the surface of the multilayer wiring board 60.

[0036] Figure 7 This is a cross-sectional view of the current detection device according to the second embodiment. Figure 7 As shown, for the current detection device 1A, the surface of the first magnetic field sensor 10A is mounted on the conductor layer 41, and the surface of the second magnetic field sensor 10B is mounted on the conductor layer 46. Furthermore, the conductor 30 forms part of the conductor layer 44. That is, a conductor 30 is disposed between the first magnetic field sensor 10A and the second magnetic field sensor 10B.

[0037] The conductor layer 43 has a first slit SLA, which has a width larger than the diameter of the magnetic sensing part 11 of the magnetic field sensor 10 and a width smaller than the distance between the two external electrodes 12 that sandwich the magnetic sensing part 11 of the magnetic field sensor 10.

[0038] The conductor layer 45 has a second slit SLB, which has a width larger than the diameter of the magnetic sensing part 11 of the magnetic field sensor 10 and a width smaller than the distance between the two external electrodes 12 that sandwich the magnetic sensing part 11 of the magnetic field sensor 10.

[0039] A first vapor-deposited film 40A for shielding electrostatic noise from entering the first magnetic field sensor 10A is bonded to the conductor layer 43 between the conductor layer 41 on which the first magnetic field sensor 10A is mounted and the conductor layer 44 constituting the conductor 30, in a manner that covers the first slit SLA. The first vapor-deposited film 40A constitutes a first conductive film.

[0040] Furthermore, a second vapor-deposited film 40B for shielding electrostatic noise from entering the second magnetic field sensor 10B is bonded to the conductor layer 45 between the conductor layer 46 where the second magnetic field sensor 10B is installed and the conductor layer 44 constituting the conductor 30, in a manner that covers the second slit SLB. The second vapor-deposited film 40B constitutes a second conductive film.

[0041] A first magnetic field sensor 10A and a second magnetic field sensor 10B are arranged opposite each other, sandwiching a conductor 30. The magnetic sensing part 11 of the first magnetic field sensor 10A is disposed on the gap G between the first region 30A and the second region 30B. Since the first magnetic field sensor 10A and the second magnetic field sensor 10B are arranged opposite each other, sandwiching a conductor 30, the magnetic sensing part 11 of the second magnetic field sensor 10B is also disposed on the gap G between the first region 30A and the second region 30B.

[0042] With this structure, the first magnetic field sensor 10A and the second magnetic field sensor 10B can equally detect the magnetic field (magnetic flux density) generated by the current flowing through the conductor 30. Therefore, the current detection device 1A does not need to adjust the voltage corresponding to the magnetic field (magnetic flux density) detected by the first magnetic field sensor 10A and / or the second magnetic field sensor 10B in the amplification circuit.

[0043] As a result, the current detection device 1A of the second embodiment can reduce the amplification circuit included in the electronic component 50 compared with the current detection device 1 of the first embodiment, and can reduce the manufacturing cost compared with the current detection device 1 of the first embodiment.

[0044] The above examples illustrate several embodiments of the present invention, but these embodiments are merely illustrative and not intended to limit the scope of the invention. These new embodiments can be implemented in a wide variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope or spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

Claims

1. A current detection device, comprising: A conductor having a first region, a second region, and a third region connecting the end of the first region and the end of the second region; A first magnetic field detection element is disposed between the first region and the second region; The second magnetic field detection element is disposed opposite to the first magnetic field detection element, sandwiching the third region; A grounding layer is disposed between the conductor and the first magnetic field detection element and the second magnetic field detection element, and has a slit wider than the width of the magnetic sensing part of the first magnetic field detection element and the second magnetic field detection element; as well as A conductive film is bonded to the grounding layer in a manner that covers the slit.

2. The current detection device according to claim 1, wherein, The slit has a width larger than the diameter of the magnetic sensing portion of the first magnetic field detection element and the second magnetic field detection element, and a width smaller than the distance between the two external electrodes that sandwich the magnetic sensing portions of the first magnetic field detection element and the second magnetic field detection element.

3. The current detection device according to claim 1, wherein, The entire surface of the conductive film in contact with the grounding layer is connected by solder-based bonding or pressing.

4. The current detection device according to claim 1, wherein, The conductive film shields the electrostatic noise entering the first magnetic field detection element and the second magnetic field detection element.

5. The current detection device according to claim 1, wherein, The current detection device has an amplification circuit that amplifies the voltage signal detected by the first magnetic field detection element and / or the second magnetic field detection element.

6. The current detection device according to any one of claims 1 to 5, wherein, The first region and the second region are arranged opposite each other with a gap between them.

7. The current detection device according to any one of claims 1 to 5, wherein, The conductive film is thinner than the conductor, and the conductive film is also thinner than the grounding layer.

8. A current detection device, comprising: A conductor having a first region, a second region, and a third region connecting the end of the first region and the end of the second region; A first magnetic field detection element is disposed between the first region and the second region; The second magnetic field detection element is disposed opposite to the first magnetic field detection element, sandwiching the conductor; A first grounding layer is disposed between the conductor and the first magnetic field detection element, and has a first slit wider than the width of the magnetic sensing portion of the first magnetic field detection element and the second magnetic field detection element; A first conductive film is adhered to the first grounding layer in such a way that it covers the first slit; The second grounding layer is disposed between the conductor and the second magnetic field detection element, and has a second slit that is wider than the width of the magnetic sensing portion of the first magnetic field detection element and the second magnetic field detection element. as well as The second conductive film is adhered to the second grounding layer in such a way that it covers the second slit.

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