Current sensor and preparation method thereof

Abstract

The invention discloses a current sensor and a preparation method thereof. The current sensor comprises a current acquisition module, a magnetic field induction module, a first magnet and a second magnet, the first magnet and the second magnet are arranged on the two sides of the magnetic field induction module in parallel. The first magnetic pole of the first magnet corresponds to the first magnetic pole of the second magnet in position, and the second magnetic pole of the first magnet corresponds to the second magnetic pole of the second magnet in position; the current acquisition module is located at the bottom side of the magnetic field induction module, and a magnetic field generated by a to-be-measured current accessed into the current acquisition module passes through the magnetic field induction module; the magnetic field induction module is used for detecting a first-direction magnetic field generated by the to-be-detected current and detecting the current value of the to-be-detected current according to the change of the first-direction magnetic field; wherein the first direction is perpendicular to the connecting line direction of the first magnetic pole and the second magnetic pole of the first magnet. According to the invention, the high-current sensor can detect a magnetic field in the horizontal direction, and the size of the current sensor can be reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power semiconductor technology, and in particular to a current sensor and a method for preparing the same. Background Art

[0002] At present, current sensors are widely used in the electronics industry. Generally, such sensors include Hall effect current sensors, which are used to sense the magnetic field generated by the current, thereby generating a Hall effect output voltage that varies in proportion to the magnetic field.

[0003] However, existing Hall effect current sensors can only sense and detect magnetic fields that pass vertically through the Hall chip. Figure 1 This is a schematic diagram of the structure of an existing Hall effect current sensor, such as Figure 1 As shown in the figure, the Hall effect current sensor includes a magnet and a Hall chip. The Hall chip is also called a Hall IC. Due to the constraint of the direction of the magnetic field, the existing Hall effect current sensor can only place the magnet vertically above or below the Hall IC. The Hall IC can only detect the magnetic field that passes vertically through the Hall IC, which limits the flexibility of the current sensor setting position. In addition, the existing Hall effect current sensor is set above the copper wire, and the Hall IC is easily disturbed by the stray magnetic field generated at the bottom of the frame. How to shield the stray magnetic field and make the magnetic field sensed by the Hall IC more uniform, thereby improving the product measurement accuracy, is the main direction of improvement of the current sensor. Summary of the invention

[0004] The present invention provides a current sensor and a preparation method thereof, so that a high current sensor can detect a magnetic field in a horizontal direction, and the detected magnetic field in the horizontal direction has a wider range, and the size of the current sensor can be reduced.

[0005] In a first aspect, an embodiment of the present invention provides a current sensor, the current sensor comprising a current acquisition module, a magnetic field sensing module, a first magnet and a second magnet;

[0006] The first magnet and the second magnet are arranged in parallel on both sides of the magnetic field sensing module; the first magnetic pole of the first magnet corresponds to the first magnetic pole of the second magnet, and the second magnetic pole of the first magnet corresponds to the second magnetic pole of the second magnet; the current acquisition module is located at the bottom side of the magnetic field sensing module, and the magnetic field generated by the current to be measured connected to the current acquisition module passes through the magnetic field sensing module;

[0007] The current acquisition module is used to access the current to be measured; the magnetic field induction module is used to detect the magnetic field in the first direction generated by the current to be measured, and detect the current value of the current to be measured according to the change of the magnetic field in the first direction; wherein, the first direction is perpendicular to the connection direction of the first magnetic pole and the second magnetic pole of the first magnet.

[0008] In a second aspect, an embodiment of the present invention further provides a method for manufacturing a current sensor. The method for manufacturing a current sensor is used to manufacture the current sensor according to any embodiment of the present invention. The method for manufacturing a current sensor includes:

[0009] Mount the first magnet and the second magnet in a non-magnetic state on the carrier film at a preset distance.

[0010] Magnetize the first magnet and the second magnet on the carrier film.

[0011] Transfer the first magnet and the second magnet on the carrier film to a first preset position and a second preset position above the current acquisition module respectively.

[0012] Set the magnetic field induction module above the current acquisition module.

[0013] Wherein, the first magnet and the second magnet are arranged in parallel on both sides of the magnetic field induction module, and the magnetic field induction module is located between the first magnet and the second magnet; the positions of the first magnetic poles of the first magnet and the second magnet correspond to each other, and the positions of the second magnetic poles of the first magnet and the second magnet correspond to each other; the current acquisition module is located on the bottom side of the magnetic field induction module, and the magnetic field generated by the current to be measured accessed in the current acquisition module passes through the magnetic field induction module.

[0014] The present invention provides a current sensor and a preparation method thereof. The current sensor includes a current acquisition module, a magnetic field induction module, a first magnet, and a second magnet. The first magnet and the second magnet are arranged in parallel on both sides of the magnetic field induction module, so that the overall thickness of the current sensor can be relatively thin and light. The positions of the magnetic poles of the first magnet and the second magnet correspond to each other, so that both the first magnet and the second magnet provide a magnetic field perpendicular to the first direction to the magnetic field induction module, thereby reducing the detection sensitivity of the magnetic field induction module. The current acquisition module is located at the bottom side of the magnetic field induction module, and the magnetic field generated by the measured current connected in the current acquisition module passes through the magnetic field induction module, enabling the magnetic field induction module to detect the magnetic field in the first direction generated by the measured current, and enabling the magnetic field induction module to detect the current value of the measured current according to the change of the magnetic field in the first direction, thereby realizing the detection of the magnetic field in the horizontal direction, and the detected range of the magnetic field in the horizontal direction is wider. In addition, the magnets in the present invention do not need to be arranged directly above or directly below the magnetic field induction module, so that the size of the current sensor can be reduced, and the manufacturing process of the current sensor can be simplified. Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of an existing Hall effect current sensor.

[0016] Figure 2 is a schematic structural diagram of a current sensor provided by an embodiment of the present invention.

[0017] Figure 3 is a schematic structural diagram of another current sensor provided by an embodiment of the present invention.

[0018] Figure 4 is a schematic cross-sectional view of a metallized silicon wafer provided by an embodiment of the present invention.

[0019] Figure 5 is a top view of a current acquisition module provided by an embodiment of the present invention.

[0020] Figure 6 is a top view of a current acquisition module in the prior art.

[0021] Figure 7 is a flowchart of a method for preparing a current sensor provided by an embodiment of the present invention.

[0022] Figure 8 is a schematic diagram of attaching a first magnet and a second magnet to a carrier film provided by an embodiment of the present invention.

[0023] Figure 9 is a flowchart of transferring a first magnet and a second magnet provided by an embodiment of the present invention.

[0024] Figure 10Schematic diagram of the relative positions of the metal plate, the first magnet, and the second magnet provided in the embodiments of the present invention.

[0025] Figure 11 Flow chart for the production of a current sensor provided in the embodiments of the present invention.

[0026] Figure 12 Flow chart for the production of an improved current sensor provided in the embodiments of the present invention. Detailed implementation manners

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the convenience of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0028] The embodiments of the present invention provide a current sensor. Figure 2 Schematic diagram of the structure of a current sensor provided in the embodiments of the present invention. As Figure 2 shown, the current sensor includes a current acquisition module 110, a magnetic field induction module 120, a first magnet 130, and a second magnet 140.

[0029] The first magnet 130 and the second magnet 140 are arranged in parallel on both sides of the magnetic field induction module 120; the positions of the first magnetic poles of the first magnet 130 and the second magnet 140 correspond, and the positions of the second magnetic poles of the first magnet 130 and the second magnet 140 correspond; the current acquisition module 110 is located at the bottom side of the magnetic field induction module 120, and the magnetic field generated by the current to be measured connected to the current acquisition module 110 passes through the magnetic field induction module 120.

[0030] The current acquisition module 110 is used to connect the current to be measured; the magnetic field induction module 120 is used to detect the magnetic field in the first direction generated by the current to be measured and detect the current value of the current to be measured according to the change in the magnetic field in the first direction; wherein, the first direction is perpendicular to the direction of the line connecting the first magnetic pole and the second magnetic pole of the first magnet 130.

[0031] In an embodiment of the present invention, the current acquisition module 110 has a patterned wire with a plurality of current input terminals and current output terminals, so that the current acquisition module 110 is connected to the current to be measured. In addition, a U-shaped current wire may be adopted in the current acquisition module 110. The U-shaped current wire is arranged on the bottom side of the magnetic field induction module 120. The current to be measured in the U-shaped current wire flows in from one end of the U-shaped current wire and flows out from the other end of the U-shaped current wire. And the width of the middle part of the U-shaped current wire close to the magnetic field induction module 120 is smaller to increase the magnetic field density passing through the magnetic field induction module 120. The current to be measured in the wire in the current acquisition module 110 can generate a spiral magnetic field, and the spiral magnetic field has a magnetic field component in the first direction. The first direction is Figure 2 the X direction shown in Figure 2 , and the first direction is perpendicular to the connection direction of the first magnetic pole and the second magnetic pole of the first magnet 130. Optionally, the first magnetic pole is the S pole and the second magnetic pole is the N pole, or the first magnetic pole is the N pole and the second magnetic pole is the S pole.

[0032] In an embodiment of the present invention, the magnetic field induction module 120 can detect the magnetic field in the horizontal direction. Exemplarily, the magnetic field induction module 120 may be an anisotropic magneto resistance (AMR) sensor. Anisotropic magneto resistance is an element with the function of reducing resistance after applying a magnetic field, and its function depends on the direction of the magnetic field lines relative to the element. Compared with a Hall IC, the anisotropic magneto resistance sensor can detect the magnetic field passing through itself in parallel, that is, it can detect the magnetic field in the horizontal direction, and the magnetic field range in the horizontal direction is wider. The first magnet 130 and the second magnet 140 may be bar magnets. The first magnet 130 and the second magnet 140 are arranged in parallel on both sides of the magnetic field induction module 120, and the magnetic field induction module 120 may be located at the middle position between the first magnet 130 and the second magnet 140. The first magnet 130 and the second magnet 140 have strong magnetism and provide a Figure 2The magnetic field component in the Y direction shown in the figure is used to reduce the sensitivity of the magnetic field induction module 120. The magnetic field component in the Y direction is also called the Y vector magnetic field. The Y vector magnetic field is the magnetic field in the direction of the connection line between the first magnetic pole and the second magnetic pole of the first magnet 130 and the second magnet 140. The Y direction is perpendicular to the first direction. Therefore, the first magnet 130 and the second magnet 140 are arranged in parallel on both sides of the magnetic field induction module 120, which can reduce the sensitivity of the magnetic field induction module 120, increase the linearity range of the magnetic field induction module 120, and the first magnet 130 and the second magnet 140 do not need to be arranged directly above or below the magnetic field induction module 120, so that the overall thickness of the current sensor can be reduced, making the current sensor have design advantages such as being small, thin and light. Since the first magnet 130 and the second magnet 140 are arranged in parallel on both sides of the magnetic field induction module 120, there is no need for the process step of vertically arranging the first magnet 130 and the second magnet 140, simplifying the manufacturing process of the current sensor.

[0033] Specifically, in the working process of the current sensor, the current to be measured is accessed through the current acquisition module 110. Based on the magnetic effect of the current, the current to be measured in the wire of the current acquisition module 110 can generate a spiral magnetic field. The magnetic field induction module 120 is used to detect the magnetic field in the first direction generated by the current to be measured. Exemplarily, the magnetic field induction module 120 generates a resistance change according to the change of the magnetic field in the first direction, determines the magnitude change of the magnetic field in the first direction according to the resistance change, and detects the current value of the current to be measured according to the change of the magnetic field in the first direction. The first direction is perpendicular to the direction of the connection line between the first magnetic pole and the second magnetic pole of the first magnet 130, that is, the magnetic field induction module 120 can detect the magnetic field in the horizontal direction, so as to realize current detection. In the prior art, the Hall sensor can only measure the magnetic field perpendicular to the Hall direction, that is Figure 2 the Z direction shown in the figure, so that the first magnet 130 and the second magnet 140 need to be arranged directly above or below the magnetic field induction module 120, resulting in an excessive thickness of the Hall effect current sensor. And since the first magnet 130 and the second magnet 140 can provide the Y vector magnetic field to the magnetic field induction module 120, it can reduce the sensitivity of the magnetic field induction module 120 and increase the linearity range of the magnetic field induction module 120.

[0034] An embodiment of the present invention provides a current sensor, which includes a current acquisition module, a magnetic field induction module, a first magnet, and a second magnet. The first magnet and the second magnet are arranged in parallel on both sides of the magnetic field induction module, so that the overall thickness of the current sensor can be relatively thin and light. The positions of the magnetic poles of the first magnet and the second magnet correspond to each other, so that both the first magnet and the second magnet provide a magnetic field perpendicular to the first direction to the magnetic field induction module, thereby reducing the detection sensitivity of the magnetic field induction module. The current acquisition module is located at the bottom side of the magnetic field induction module. The magnetic field generated by the measured current connected to the current acquisition module passes through the magnetic field induction module, enabling the magnetic field induction module to detect the magnetic field in the first direction generated by the measured current, and enabling the magnetic field induction module to detect the current value of the measured current according to the change of the magnetic field in the first direction, thereby realizing the detection of the magnetic field in the horizontal direction, and the detected magnetic field range in the horizontal direction is wider. In addition, the magnets in the present invention do not need to be arranged directly above or below the magnetic field induction module, so that the size of the current sensor can be reduced, and the manufacturing process of the current sensor can be simplified.

[0035] To reduce the interference of stray magnetic fields, the current sensor according to the embodiment of the present invention Figure 3 is a schematic structural diagram of another current sensor provided by the embodiment of the present invention. Referring to Figure 3 , the current sensor further includes a metallized silicon wafer 150; the metallized silicon wafer 150 is disposed between the current acquisition module 110 and the magnetic field induction module 120.

[0036] Figure 4 is a schematic cross-sectional view of the metallized silicon wafer provided by the embodiment of the present invention. The metallized silicon wafer 150 includes a metal layer 151 and a silicon dioxide layer 152; the metal layer 151 is in contact with the magnetic field induction module 120, and the silicon dioxide layer 152 is in contact with the current acquisition module 110.

[0037] Among them, referring to Figure 2 and Figure 3 , an Application Specific Integrated Circuit (ASIC) chip and the magnetic field induction module 120 are both disposed at the middle position on the same horizontal plane between the first magnet 130 and the second magnet 140. The ASIC chip is connected to the magnetic field induction module 120. Based on the magnetic effect of the current, after the internal magnetic field quantity is sensed by the built-in magnetic sensor in the magnetic field induction module 120, it is converted into a voltage signal to realize isolated current measurement. The detected current value of the measured current can be sent to the ASIC chip, and the ASIC chip further processes according to the current value of the measured current. Figure 2 and Figure 3 One end of the frame secondary side pin in can be connected to the ASIC chip, and the other end of the frame secondary side pin can be connected to an external circuit to realize the corresponding functions of the ASIC chip.

[0038] Specifically, the metallized silicon wafer 151 introduced into the semiconductor package acts as a spacer. The metal layer 151 on the silicon dioxide layer 152 plays a role in ground shielding, improving the anti-interference ability of the magnetic field induction module 120 against chaotic magnetic fields. It can achieve the measurement of direct current and alternating current under isolation conditions, with an insulation dielectric strength meeting 6KV / 50HZ / 60S. The wire current impedance of the current acquisition module 110 is <0.5mΩ, so that when the wire of the current acquisition module 110 works, the heat generation is smaller, and it can work in the temperature range of -40 to 105°C, performing high-precision and low-temperature drift current detection.

[0039] For the existing Hall sensors placed above the wire, the eddy current flowing through the wire will increase with the increase of time and the alternating magnetic field frequency. The eddy current brings chaotic magnetic fields, interfering with the magnetic field induction amount of the Hall sensors above the wire, and further affecting the product accuracy and bringing noise interference. Therefore, in the embodiments of the present invention, by introducing the metallized silicon wafer 150 of the semiconductor package as a spacer, the metal layer 151 of the metallized silicon wafer 150 plays a role in ground shielding, reducing the interference of the stray magnetic field, making the magnetic field sensed by the magnetic field induction module 120 more uniform, and at the same time reducing the interference brought by the noise signal.

[0040] In addition, the thickness of the metal layer 151 is 0.1μm - 0.25μm, and it can be made of materials such as gold, aluminum, silver, etc. The thickness of the silicon dioxide layer 152 can be freely increased or decreased to adapt to the internal dimensions of the current sensor. Preferably, the thickness of the silicon dioxide layer 152 is 50μm - 700μm.

[0041] Optionally, continue to refer to Figure 3 , the current sensor further includes an insulating gasket 160, and the insulating gasket 160 is located between the metallized silicon wafer 150 and the current acquisition module 110.

[0042] Specifically, the insulating gasket 160 is a polyimide gasket, which can play an insulating role, and as a gasket for the metallized silicon wafer 150, it can improve the stability of the internal structure of the current sensor.

[0043] Optionally, the magnetic field induction module 120 includes an anisotropic magnetoresistive sensor.

[0044] Specifically, anisotropic magnetoresistance is an element with the function of reducing resistance after applying a magnetic field. Its function depends on the direction of the magnetic field lines relative to the element. Compared with the Hall IC, the anisotropic magnetoresistive sensor can detect the magnetic field parallel to itself, that is, it can detect the magnetic field in the horizontal direction, and the magnetic field range in the horizontal direction is wider.

[0045] Optionally, the first magnet 130 and the second magnet 140 are rectangular magnets. The dimensions of the rectangular magnet are length × width × height = 2.67 * 1.0 * 0.5 mm. Since the magnet has strong magnetism, it is easy to adsorb on any metal parts made of iron-nickel materials. At the same time, the required distance between the two rectangular magnets during the chip mounting process is 3.43 mm. At such a small distance, there are also problems of like-pole repulsion and opposite-pole attraction between the two rectangular magnets.

[0046] Optionally, the manufacturing materials of the first magnet 130 and the second magnet 140 can be selected as sintered NdFeB permanent magnet materials, national standard variety UH. After the powder magnetic materials are sintered and formed, they are cut into the size of the existing product = 2.5X1.0X0.5 mm, and the magnetic field strength > 60 GS. In order to increase the magnetic flux of a single volume, by adjusting the dimensions of the first magnet 130 and the second magnet 140, such as making a rectangular magnet with dimensions = 2.5X1.20X0.8 mm, the magnetic field strength > 89 GS. In addition, samarium cobalt magnet materials can also be selected to replace the NdFeB permanent magnet materials.

[0047] The encapsulation of existing Hall sensor products is restricted by the encapsulation volume size and material process. The area of the copper wire in the internal frame cannot be made large, so the continuous current-carrying capacity is limited, and the current-carrying capacity < 150 A. In order to increase the induced magnetic field amount of the Hall sensor, the existing method is to increase the Hall coupling factor value. By optimizing the matching between the frame and the Hall, the ability of the copper frame per unit current to convert the magnetic field is improved, thereby increasing the sensitivity of the Hall sensor. However, if the sensitivity is too high, the detected linearity range will be too small. In the embodiments of the present invention, the first magnet 130 and the second magnet 140 are used to give a Y vector magnetic field to the magnetic field induction module 120 to reduce the sensitivity of the magnetic field induction module 120 and increase the linearity range. The linearity range can be achieved within the range of 5 A - 100 A. The U-shaped current wire pattern inside the current acquisition module 110 is optimized. The width of the central wire of the U-shaped current wire decreases near the magnetic field induction module 120 to increase the magnetic field density. The relative position deviation between the magnetic field induction module 120 and the current acquisition module 110 during the chip mounting process is controlled within 30 um to improve the measurement accuracy of the product. In addition, the height of the magnetic field induction module 120 relative to the original side current wire of the bottom frame can be adjusted. The height of the magnetic field induction module 120 from the original side of the bottom frame can be 500 um, and the required measurement current range meets 50 A; the height of the magnetic field induction module 120 can also be 650 um, and the required measurement current range is 75 A.

[0048] Optionally, continue to refer to Figure 3 , the current acquisition module 110 includes a first current wire 111 and a second current wire 112. The output end of the first current wire 111 is connected to the input end of the second current wire 112.

[0049] Both the first current-carrying wire 111 and the second current-carrying wire 112 pass through the bottom side of the magnetic field induction module 120, and the directions of the currents to be measured in the first current-carrying wire 111 and the second current-carrying wire 112 are opposite. The magnetic field in the first direction generated by the currents to be measured in the first current-carrying wire 111 and the second current-carrying wire 112 passes through the magnetic field induction module 120.

[0050] Among them, the output end of the first current-carrying wire 111 is connected to the input end of the second current-carrying wire 112. The first current-carrying wire 111 has two input ends A1, and the second current-carrying wire 112 has two output ends B1. The input end A1 of the first current-carrying wire 111 and the output end B1 of the second current-carrying wire 112 can both be used as the frame primary side wire pins of the current sensor. The current to be measured is input from the input end A1 of the first current-carrying wire 111, passes through the output end of the first current-carrying wire 111 to the input end of the second current-carrying wire 112, and is output from the output end B1 of the second current-carrying wire 112. A magnetic field will be generated during the transmission of the current to be measured. The magnetic field in the first direction generated by the currents to be measured in the first current-carrying wire 111 and the second current-carrying wire 112 passes through the magnetic field induction module 120. The magnetic field induction module 120 further detects the magnetic field in the first direction generated by the current to be measured and detects the current value of the current to be measured according to the change in the magnetic field in the first direction.

[0051] Specifically, the current acquisition module 110 includes a first current-carrying wire 111 and a second current-carrying wire 112. The output end of the first current-carrying wire 111 is connected to the input end of the second current-carrying wire 112. Both the first current-carrying wire 111 and the second current-carrying wire 112 pass through the bottom side of the magnetic field induction module 120, so that a U-shaped current-carrying wire can be formed. The current to be measured in the U-shaped current-carrying wire flows in from one end of the U-shaped current-carrying wire and flows out from the other end of the U-shaped current-carrying wire. Moreover, the width of the middle part of the U-shaped current-carrying wire close to the magnetic field induction module 120 is small to increase the magnetic field density passing through the magnetic field induction module 120. The directions of the currents to be measured in the first current-carrying wire 111 and the second current-carrying wire 112 are opposite. The magnetic field in the first direction generated by the currents to be measured in the first current-carrying wire 111 and the second current-carrying wire 112 passes through the magnetic field induction module 120.

[0052] Optionally, continue to refer to Figure 3 , the current sensor further includes a housing 170; the housing 170 wraps the current acquisition module 110, the magnetic field induction module 120, the first magnet 130 and the second magnet 140, and only exposes the input end A1 of the first current-carrying wire 111 and the output end B1 of the second current-carrying wire 112.

[0053] Specifically, the housing 170 is a semiconductor packaging housing, and the housing 170 also exposes the frame secondary side pins, so that the frame secondary side pins can be connected to external circuits.

[0054] Optionally,Figure 5 This is a top view of the current acquisition module provided by the embodiment of the present invention. Figure 6 This is a top view of the current acquisition module in the prior art. As Figure 5 shown, a first base island structure 1111 is provided on the first current wire 111, and a second base island structure 1121 is provided on the second current wire 112. The first base island structure 1111 is used to place the first magnet 130, and the second base island structure 1121 is used to place the second magnet 140.

[0055] Specifically, the wire frame formed by the current acquisition module in the prior art does not have a position for setting magnets. In the embodiment of the present invention, referring to Figure 5 , the wire frame of the current acquisition module 110 has a base island structure design for supporting the first magnet 130 and the second magnet 140. The first current wire 111 and the second current wire 112 are symmetric left and right, so the first base island structure 1111 and the second base island structure 1121 are also symmetric left and right, which is conducive to placing the first magnet 130 and the second magnet 140 according to the size and position. And after optimizing the wire frame formed by the current acquisition module, the magnetic field induction module 120 can be placed between the first magnet 130 and the second magnet 140 in a plane area. The magnetic field in the X direction generated by the current passing through the bottom copper frame can be sensed at the parallel position of the middle groove notch, and at the same time, the fixed magnetic field in the Y direction provided by the two magnets can also be sensed, so as to realize the detection of the magnetic field in the horizontal direction, and the detected magnetic field range in the horizontal direction is wider.

[0056] Optionally, referring to Figure 5 , a plurality of fixing holes are provided on both the first base island junction 1111 and the second base island structure 1112. The fixing holes are used to fix the current acquisition module 110, the first magnet 130 and the second magnet 140.

[0057] Specifically, the first magnet 130 and the second magnet 140 can be cured on the first base island junction 1111 and the second base island structure 1112 by glue. The fixing holes can increase the contact area between the glue and the first base island junction 1111 and the second base island structure 1112, so as to increase the fixing force between the current acquisition module 110, the first magnet 130 and the second magnet 140, and improve the stability of the structure.

[0058] The embodiment of the present invention provides a current sensor. The current sensor can realize the detection of the magnetic field in the horizontal direction, and the detected magnetic field range in the horizontal direction is wider. The metal layer of the metallized silicon wafer is used to play a role of grounding and shielding, reducing the interference of the stray magnetic field, making the magnetic field sensed by the magnetic field induction module more uniform, and at the same time reducing the interference brought by the noise signal. In addition, the magnets in the present invention do not need to be arranged directly above or below the magnetic field induction module, so the size of the current sensor can be reduced, and the manufacturing process of the current sensor can be simplified.

[0059] The embodiment of the present invention also provides a method for preparing a current sensor. Figure 7 A flow chart of a method for preparing a current sensor provided by an embodiment of the present invention, Figure 8 Schematic diagram of the first magnet and the second magnet provided in the embodiment of the present invention being attached to the supporting film, the current sensor preparation method is used to prepare the current sensor in any embodiment of the present invention, such as Figure 7 As shown, the current sensor preparation method includes:

[0060] S110, mounting the first magnet and the second magnet in a non-magnetic state onto the supporting film at a preset distance.

[0061] S120, magnetizing the first magnet and the second magnet on the supporting film.

[0062] S130, transferring the first magnet and the second magnet on the supporting film to the first preset position and the second preset position above the current collection module respectively.

[0063] S140. Set the magnetic field sensing module above the current acquisition module; wherein the first magnet and the second magnet are arranged in parallel on both sides of the magnetic field sensing module, and the magnetic field sensing module is located between the first magnet and the second magnet; the positions of the first magnetic pole of the first magnet and the first magnetic pole of the second magnet correspond to each other, and the positions of the second magnetic pole of the first magnet and the second magnetic pole of the second magnet correspond to each other; the current acquisition module is located on the bottom side of the magnetic field sensing module, and the magnetic field generated by the current to be measured connected to the current acquisition module passes through the magnetic field sensing module.

[0064] Among them, Figure 8 As shown, due to the introduction of the first magnet 130 and the second magnet 140, the first magnet 130 and the second magnet 140 are two identical magnets, and the magnets can be rectangular parallelepiped magnets. The two magnets may have the problem of repulsion of the same polarity and attraction of the opposite polarities. Based on this, the preparation process of the current sensor is innovated, and a magnet film lamination process is introduced. Optionally, the supporting film 20 is a blue film, a blue film organic material film, and exemplarily, the blue film is a UV film.

[0065] Specifically, after the material preparation of the first magnet 130 and the second magnet 140 is completed, using the existing automated flexible vibrating bowl + robotic arm + vision recognition system, multiple non-magnetic first magnets 130 and second magnets 140 can be mounted on the supporting film 20 at a preset distance d. The preset distance d ensures that the magnetism between two magnets is not sufficient to adsorb together. At the same time, the magnets located on the supporting film 20 can facilitate the subsequent automated chip mounting machine to identify the rectangular magnets. Using automated production improves production efficiency. At the same time, it solves the problem that the rectangular magnets are magnetized by themselves and are extremely easy to adsorb together, making automated production impossible and only manual separation and then mounting can be carried out. During the automated production process, the non-magnetic magnet materials on the entire supporting film 20 can be magnetized through a unified magnetization action. The first magnets 130 and second magnets 140 on the supporting film 20 are magnetized. In this way, all the materials on the supporting film 20 have magnetism. However, due to the spacing reserved in advance in the mounting of the supporting film 20 to ensure that the magnetism between two magnets is not sufficient to adsorb together, and at the same time, the viscosity of the supporting film 20 can also reduce the problem of two magnets adsorbing together. The first magnet 130 and the second magnet 140 on the supporting film 20 are respectively transferred to the first preset position and the second preset position above the current acquisition module 110, and finally the magnetic field induction module 120 is arranged above the current acquisition module 110. Refer to Figure 5 , the first preset position is the position where the first base island structure 1111 is located, and the second preset position is the position where the second base island structure 1121 is located, so that the first magnet 130 and the second magnet 140 are arranged in parallel on both sides of the magnetic field induction module 120; the positions of the first magnetic poles of the first magnet 130 and the second magnet 140 correspond, and the positions of the second magnetic poles of the first magnet 130 and the second magnetic poles of the second magnet 140 correspond; the current acquisition module 110 is located at the bottom side of the magnetic field induction module 120, and the magnetic field generated by the measured current connected to the current acquisition module 110 passes through the magnetic field induction module 120. In the prior art, since the magnets are magnetic, two magnets are easily adsorbed together, and usually the magnets are mounted by manual mounting. In the embodiment of the present invention, the first magnet 130 and the second magnet 140 are mounted by the supporting film 20, so as to use an automated device to replace the manual mounting method and improve the yield of the current sensor finished product. The manual mounting process of rectangular magnets includes two mounting actions. After simplification, only one mounting action is required to complete the mounting of the first magnet 130 and the second magnet 140. The entire process flow is simplified and the production efficiency is improved.

[0066] An embodiment of the present invention provides a method for manufacturing a current sensor. The method for manufacturing the current sensor includes mounting a first magnet and a second magnet in a non-magnetic state on a carrier film at a preset distance, magnetizing the first magnet and the second magnet on the carrier film, transferring the first magnet and the second magnet on the carrier film to a first preset position and a second preset position above a current acquisition module respectively, and finally arranging a magnetic field induction module above the current acquisition module. The entire process flow is simplified, and the production efficiency is improved. Moreover, the manufactured current sensor can detect the magnetic field in the horizontal direction, and the detected horizontal magnetic field range is wider. The metal layer of the metallized silicon wafer is used to play a role of ground shielding, reducing the interference of stray magnetic fields, making the magnetic field sensed by the magnetic field induction module more uniform, and at the same time reducing the interference caused by noise signals. In addition, in the embodiment of the present invention, the magnets do not need to be arranged directly above or below the magnetic field induction module, thereby reducing the size of the current sensor.

[0067] In the embodiment of the present invention, a new fixture is designed in the wafer mounting process, which solves the problem that two magnets cannot be normally mounted and produced due to magnetic repulsion or attraction before the glue cures, simplifies the wafer mounting sequence, and completes the mounting of two magnets in one wafer mounting, improving the efficiency.

[0068] Optionally, Figure 9 is a flowchart for transferring the first magnet and the second magnet provided in the embodiment of the present invention. Figure 10 is a schematic diagram of the relative positions of a metal plate, the first magnet, and the second magnet provided in the embodiment of the present invention. As Figure 9 shown, transferring the first magnet and the second magnet on the carrier film to the first preset position and the second preset position above the current acquisition module respectively includes:

[0069] S210. Set a metal plate below the current acquisition module.

[0070] S220. Attach the first magnet on the carrier film to the first preset position above the current acquisition module with glue, and attach the second magnet on the carrier film to the second preset position above the current acquisition module with glue.

[0071] S230. Cure the glue at the positions of the first magnet and the second magnet to fix the first magnet to the first preset position and fix the second magnet to the second preset position.

[0072] S240. Remove the metal plate below the current acquisition module.

[0073] Among them, as Figure 10As shown, the current acquisition module 110 is arranged on the frame. Multiple current acquisition modules 110 can be arranged on the same frame at the same time, so as to batch produce the current sensor in the embodiment of the present invention through an automated device. A metal plate is introduced and arranged below the current acquisition module 110. The metal plate can be an iron-based metal plate with dimensions of length×width×thickness = 240X80X0.24mm. The iron-based metal plate can be placed and moved together with the frame in the automated device and pushed into the cartridge. Due to the magnetic attraction of the iron-based metal plate below, as long as the position of the mounted piece is fixed, problems such as the two magnets attracting each other before the glue is cured, or the position shifting due to magnetic repulsion and being adsorbed by other magnetic materials can be overcome.

[0074] Specifically, the metal plate is arranged below the current acquisition module 110. The first magnet 130 on the support film 20 is attached to the first preset position above the current acquisition module 110 through glue, and the second magnet 140 on the support film is attached to the second preset position above the current acquisition module 110 through glue. The first magnet 130 and the second magnet 140 are magnetically attracted by the iron-based metal plate below, and the positions of the first magnet 130 and the second magnet 140 will be fixed differently, so as to overcome problems such as the two magnets attracting each other before the glue is cured, or the position shifting due to magnetic repulsion and being adsorbed by other magnetic materials. In addition, referring to Figure 5 , the first preset position is the position where the first base island structure 1111 is located, and the second preset position is the position where the second base island structure 1121 is located, so that the first magnet 130 and the second magnet 140 are arranged in parallel on both sides of the magnetic field induction module 120.

[0075] Before the glue is cured, the metal sheet can be transferred to the cartridge together with the frame where the current acquisition module 110 is located, and the glue at the positions of the first magnet 130 and the second magnet 140 is cured, so that the first magnet 130 is fixed to the first preset position and the second magnet 140 is fixed to the second preset position, and then the metal plate below the current acquisition module is removed for reuse in a new round of production.

[0076] Optionally, the glue for fixing the first magnet 130 and the second magnet 140 can be a UV glue resistant to 200°C high temperature. The order of installing the magnets: install the left one first. Under the irradiation of the ultraviolet light source, the glue can cure the left magnet in 30s, and then install the second magnet. The ultraviolet light source can be installed in the area where the magnets on the equipment guide rail are installed, in a semi-closed state, separated from the area where the magnets are installed in front to prevent the ultraviolet light from irradiating. Limiting the ultraviolet light source to irradiate in the area where the magnets are mounted can cure the glue at the magnet positions within 30s.

[0077] Optionally, transferring the first magnet and the second magnet on the carrier film to a first preset position and a second preset position above the current acquisition module respectively includes:

[0078] Setting a metal plate below the current acquisition module; pasting the first magnet on the carrier film to the first preset position above the current acquisition module with glue, curing the glue at the position of the first magnet to fix the first magnet to the first preset position; pasting the second magnet on the carrier film to the second preset position above the current acquisition module with glue, curing the glue at the position of the second magnet to fix the second magnet to the second preset position; removing the metal plate below the current acquisition module.

[0079] Specifically, in the process of transferring the first magnet 130 and the second magnet 140 on the carrier film 20 to the first preset position and the second preset position above the current acquisition module respectively, the first magnet 130 and the second magnet 140 can be transferred separately, so that the mounting glue of the first magnet 130 and the second magnet 140 can be cured in batches, so that the first magnet 130 and the second magnet 140 can be mounted more firmly.

[0080] Figure 11 This is a production flow chart of a current sensor provided in an embodiment of the present invention. Figure 12 This is a production flow chart of an improved current sensor provided in an embodiment of the present invention. As Figure 11 shown, in the production process of the current sensor, the production steps include: wafer thinning, wafer dicing, die bonding 1 polyimide gasket installation, die bonding 2 metallized silicon wafer, baking and curing 1, die bonding 3 ASICic (ASIC chip), die bonding 4 AMRSensor (anisotropic magnetoresistive sensor), baking and curing 2, manual die bonding 5 rectangular magnet 1, baking and curing 3, manual die bonding 6 rectangular magnet 2, baking and curing 4, ion cleaning before bonding, bonding, plastic encapsulation, post-encapsulation curing, electroplating, laser printing, lead frame forming, appearance inspection and packaging. In the production process of the improved current sensor, compared with the production steps in Figure 11 the steps before manual die bonding 5 are simplified, and steps of automatically pasting a blue film on a non-magnetic rectangular magnet and magnetizing the rectangular magnet with the blue film pasted are added, which facilitates the identification of the rectangular magnet by the subsequent automatic die bonding machine, enables the use of automatic production, improves the production efficiency, and at the same time solves the problem that the rectangular magnets are magnetized themselves and are extremely easy to adsorb to each other, making it impossible to perform automatic production and only allowing manual separation and then mounting.

[0081] At the same time, a new fixture is designed in the manual chip mounting process. A metal plate made of iron-based material is introduced at the bottom of the frame. The size of the metal plate is length×width×height = 240X80X0.24mm. The iron-based metal plate can be placed and moved with the frame in the automated equipment and pushed into the magazine. Due to the magnetic attraction of the iron-based metal plate below, as long as the position of the chip mounting size is fixed, it can overcome the problems that before the glue is cured, the two magnets on the frame are attracted to each other, or due to magnetic repulsion, the position is shifted and adsorbed by other magnetic materials, resulting in abnormal chip mounting production. The improved production process simplifies the chip mounting sequence, and two magnets are completed in one chip mounting, improving the efficiency.

[0082] The embodiment of the present invention provides a method for preparing a current sensor. The method for preparing a current sensor solves the problem that the cuboid magnets are magnetized by themselves and are extremely easy to be attracted to each other, making automated production impossible and only manual separation and mounting can be relied on. The entire process flow is simplified and the production efficiency is improved. The manufactured current sensor can detect the magnetic field in the horizontal direction, and the detected magnetic field range in the horizontal direction is wider. The metal layer of the metallized silicon wafer is used to play a role of ground shielding, reducing the interference of the stray magnetic field, making the magnetic field sensed by the magnetic field induction module more uniform, and at the same time reducing the interference caused by the noise signal. In addition, the magnets in the embodiment of the present invention do not need to be arranged directly above or below the magnetic field induction module, so the size of the current sensor can be reduced.

[0083] Note that the above is only the preferred embodiment of the present invention and the applied technical principle. Those skilled in the art will understand that the present invention is not limited to the specific embodiments here. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A current sensor, characterized in that, The current sensor includes a current acquisition module, a magnetic field induction module, a first magnet, and a second magnet; The first magnet and the second magnet are arranged in parallel on both sides of the magnetic field induction module; The positions of the first magnetic poles of the first magnet and the second magnet correspond to each other, and the positions of the second magnetic poles of the first magnet and the second magnet correspond to each other; the current acquisition module is located at the bottom side of the magnetic field induction module, and the magnetic field generated by the measured current connected in the current acquisition module passes through the magnetic field induction module; The current acquisition module is used to connect the measured current; the magnetic field induction module is used to detect the magnetic field in the first direction generated by the measured current and detect the current value of the measured current according to the change of the magnetic field in the first direction; wherein, the first direction is perpendicular to the direction of the line connecting the first magnetic pole and the second magnetic pole of the first magnet.

2. The current sensor according to claim 1, wherein The current sensor further includes a metallized silicon wafer; The metallized silicon wafer is arranged between the current acquisition module and the magnetic field induction module, and the metallized silicon wafer includes a metal layer and a silicon dioxide layer; the metal layer is in contact with the magnetic field induction module, and the silicon dioxide layer is in contact with the current acquisition module.

3. The current sensor according to claim 2, characterized in that, An insulating gasket is further included, and the insulating gasket is located between the metallized silicon wafer and the current acquisition module.

4. The current sensor according to claim 1, characterized in that, The current acquisition module includes a first current wire and a second current wire, and the output end of the first current wire is connected to the input end of the second current wire; Both the first current wire and the second current wire pass through the bottom side of the magnetic field induction module, and the flowing directions of the measured currents in the first current wire and the second current wire are opposite, and the magnetic field in the first direction generated by the measured currents in the first current wire and the second current wire passes through the magnetic field induction module.

5. The current sensor according to claim 4, characterized in that, The current sensor further includes a housing; The housing wraps the current acquisition module, the magnetic field induction module, the first magnet, and the second magnet, and only the input end of the first current wire and the output end of the second current wire are exposed.

6. The current sensor according to claim 4, wherein, A first base island structure is provided on the first current wire, and a second base island structure is provided on the second current wire. The first base island structure is used to place the first magnet, and the second base island structure is used to place the second magnet.

7. The current sensor according to claim 6, wherein, A plurality of fixing holes are provided on both the first base island structure and the second base island structure, and the fixing holes are used to fix the current acquisition module, the first magnet, and the second magnet.

8. The current sensor according to claim 1, wherein, The magnetic field induction module includes an anisotropic magnetoresistive sensor.

9. A method for preparing a current sensor, characterized in that, The method for manufacturing the current sensor is used to manufacture the current sensor according to any one of claims 1-8 above, and the method for manufacturing the current sensor includes: Mount the first magnet and the second magnet in a non-magnetic state on a carrier film according to a preset distance; Magnetize the first magnet and the second magnet on the carrier film; Transfer the first magnet and the second magnet on the carrier film to a first preset position and a second preset position above the current acquisition module respectively; Set the magnetic field induction module above the current acquisition module; Among them, the first magnet and the second magnet are arranged in parallel on both sides of the magnetic field induction module, and the magnetic field induction module is located between the first magnet and the second magnet; the positions of the first magnetic poles of the first magnet and the second magnet correspond to each other, and the positions of the second magnetic poles of the first magnet and the second magnet correspond to each other; the current acquisition module is located at the bottom side of the magnetic field induction module, and the magnetic field generated by the current to be measured connected in the current acquisition module passes through the magnetic field induction module.

10. The method for manufacturing a current sensor according to claim 9, characterized in that, The transferring the first magnet and the second magnet on the supporting film to the first preset position and the second preset position above the current acquisition module respectively includes: Setting a metal plate below the current acquisition module; Attaching the first magnet on the supporting film to the first preset position above the current acquisition module with glue, and attaching the second magnet on the supporting film to the second preset position above the current acquisition module with glue; Curing the glue at the positions where the first magnet and the second magnet are located, so that the first magnet is fixed to the first preset position and the second magnet is fixed to the second preset position; Removing the metal plate below the current acquisition module.

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