Sensor devices

Abstract

A sensor device includes a current conductor designed to carry an electric current, a differential magnetic field sensor chip arranged in an opening of the current conductor and designed to detect a magnetic field generated by the electric current, and a metal plate arranged over the current conductor and over the magnetic field sensor chip.

Description

Technical field

[0001] The present disclosure relates to sensor devices and methods for manufacturing sensor devices. background

[0002] Magnetic field sensors can be used to measure the strength of an electric current flowing through a conductor. For this purpose, the strength of the magnetic field induced by the electric current at the location of the magnetic field sensor must be sufficiently high. One way to achieve this is, for example, to reduce the cross-section of the conductor at the location of the magnetic field sensor. However, a reduced conductor cross-section can lead to increased power dissipation in the magnetic field sensor.

[0003] Document US 2024 / 0036084A1 relates to a current sensor system capable of measuring alternating currents with frequencies up to approximately 2 kHz. Document US 2017 / 0285076A1 relates to a current sensor that maintains its shielding function even when detecting large currents and also prevents detection errors due to eddy currents. Document DE 102019121385A1 relates to devices and methods for mounting a magnetic field sensor chip on a busbar.

[0004] Manufacturers and developers of sensor devices are constantly striving to improve their products. Increasing the measurement accuracy of sensor devices without incurring increased power losses can be of particular interest. Furthermore, providing suitable methods for manufacturing such sensor devices can be of interest. Brief description

[0005] Several aspects pertain to a sensor device. The sensor device comprises a conductor designed to carry an electric current. The sensor device further comprises a differential magnetic field sensor chip arranged in an opening of the conductor and designed to detect a magnetic field generated by the electric current. The sensor device also comprises a metal plate arranged over the conductor and the magnetic field sensor chip. The metal plate and the conductor are encapsulated in a first encapsulation material, and the magnetic field sensor chip is arranged outside the first encapsulation material. The magnetic field sensor chip is encapsulated in a second encapsulation material, and the conductor is arranged outside the second encapsulation material.The first encapsulation material has a depression, and the second encapsulation material, with the magnetic field sensor chip encapsulated within it, is arranged in the depression.

[0006] The person skilled in the art will recognize further features and advantages of the invention when reading the following detailed description and when looking at the accompanying drawings. Brief description of the drawings

[0007] The present disclosure is illustrated by way of example and is not limited to the depictions in the accompanying drawings, in which the same reference numerals may refer to similar or identical elements. The elements in the drawings are not necessarily shown to scale. The features of the various examples shown may be combined, provided they are not mutually exclusive. Fig. 1 contains the Fig. 1A and Fig. 1B, showing a side cross-sectional view or a bottom view of a sensor device 100 according to the disclosure. Fig. 2 contains the Fig. 2A and Fig. 2B, which show the dependence of a magnetic field strength or a phase error of the magnetic field strength on the frequency of an electric measuring current for the case of a sensor device according to the disclosure and for the case of a conventional sensor device. Fig. Figure 3 shows a flowchart of a process for manufacturing a sensor device according to the disclosure. Detailed description

[0008] The Fig. 1A and Fig. Figure 1B shows a side cross-sectional view or a bottom view of a sensor device 100 according to the disclosure. It should be noted that in the bottom view of the Fig. 1B For illustrative reasons, not all of the following described components of the sensor device 100 are shown.

[0009] The sensor device 100 can comprise a current conductor 2, a differential magnetic field sensor chip 4 arranged in an opening 6 of the current conductor 2, and a metal plate 8 arranged above the current conductor 2 and above the magnetic field sensor chip 4. In the example shown, the current conductor 2 can extend in the x-direction in the vicinity of the opening 6. The current conductor 2 can be configured to carry an electric current, thereby generating or inducing a magnetic field 10 whose field lines can extend around the current conductor 2. The magnetic field sensor chip 4 can be configured to detect the magnetic field 10 generated by the electric current.

[0010] The differential magnetic field sensor chip 4 can be an integrated circuit or a semiconductor chip, so it can also be referred to as a differential magnetic field sensor IC. The differential magnetic field sensor chip 4 can have a first sensor element 12A and a second sensor element 12B. In the example shown, the two sensor elements 12A and 12B can be spaced apart in the z-direction, i.e., they can be arranged on a (straight) line extending in the z-direction. The two sensor elements 12A and 12B can be sensitive in the y-direction, i.e., designed to detect the y-component of the magnetic field 10 induced by the electric current at the location of the respective sensor element. Of course, one or both of the sensor elements 12A and 12B can also be sensitive with respect to other spatial directions, for example, with respect to the x- and / or z-direction.Each of the two sensor elements 12A and 12B can generate a signal corresponding to the respective detected magnetic field component. By calculating the difference or sum of the two signals (or the two detected magnetic field components), the electric current flowing through the conductor 2 can be determined. The magnetic field sensor chip 4 can therefore also be referred to as a current sensor or current sensor chip.

[0011] The differential magnetic field sensor chip 4, or its sensor elements 12A and 12B, are not limited to a specific sensor technology. In one example, the sensor elements 12A and 12B can correspond to Hall effect sensors. In other examples, the sensor elements 12A and 12B can be magnetoresistive xMR sensor elements, in particular AMR, GMR, or TMR sensor elements. For example, each of the sensor elements 12A and 12B can be implemented as a resistor bridge with, for example, four resistors. In one example, the resistors can be arranged in the form of a Wheatstone bridge. The sensor elements 12A and 12B can be integrated into a circuit of the magnetic field sensor chip 4. Such a circuit can also include signal amplification, analog-to-digital conversion, digital signal processing, and / or offset and temperature compensation.In addition to the components of the respective sensor element, components for signal amplification and / or analog-to-digital conversion may or may not be considered part of the sensor elements 12A and 12B.

[0012] The conductor 2 can also be referred to as a busbar and may be made, for example, of at least one of copper, aluminum, or alloys thereof. The conductor 2 may have a (particularly constant) dimension a in the y-direction in the vicinity of the opening 6, which, in a non-limiting example, may be in a range of approximately 12 mm to approximately 20 mm (for example, at approximately 16 mm). In the z-direction, the conductor 2 may have a dimension b, which, in a non-limiting example, may be in a range of approximately 1 mm to approximately 2.5 mm (for example, at approximately 1.5 mm). In the bottom view of the Fig. In 1B, the opening 6 of the conductor 2 can have a substantially rectangular shape. In other examples, the opening 6 can have a different shape, for example, round, circular, oval, elliptical, square, or similar. From the bottom view of the Fig. Figure 1B shows that the sensor elements 12A and 12B of the magnetic field sensor chip 4 can be arranged offset from the center of the opening 6. The offset c can be in a range of approximately 0.5 mm to approximately 1.5 mm (for example, approximately 1 mm).

[0013] The metal plate 8 can also be called a metal plate, metal sheet, flux plate, or flux plate and can be made of at least one of copper, aluminum, or alloys thereof. For example, the metal plate 8 can be produced by a stamping process. In the x-direction, the metal plate 8 can have a dimension d, which in a non-limiting example can be in a range of approximately 12 mm to approximately 20 mm (for example, approximately 16 mm). In the y-direction, the metal plate 8 can have a dimension e, which in a non-limiting example can be in a range of approximately 15 mm to approximately 25 mm (for example, approximately 20 mm). The dimension e of the metal plate 8 in the y-direction can be larger than the dimension a of the conductor 2 in the y-direction. Furthermore, the dimension e of the metal plate 8 in the y-direction can be larger than the dimension d of the metal plate 8 in the x-direction.In the z-direction, the metal plate 8 can have a dimension f, which in a non-restrictive example can be in a range of approximately 0.5 mm to approximately 1.5 mm (for example, approximately 1 mm). A distance g from the top of the busbar 2 to the bottom of the metal plate 8 can, in a non-restrictive example, be in a range of approximately 2.5 mm to approximately 5 mm (for example, approximately 2.5 mm).

[0014] In the exemplary bottom view of the Fig. In 1B, the metal plate 8 can have a rectangular shape. In other examples, the metal plate 8 can have a different shape, for example, round, circular, oval, elliptical, square, or similar. In the example shown, the corners of the metal plate 8 can be essentially pointed. In other examples, the corners of the metal plate 8 can also be rounded. In the bottom view shown, the metal plate 8 can be, in particular, closed and have no openings. From the side view of the Fig. Figure 1A shows that the metal plate 8 can run parallel to the conductor 2. In the example shown, the metal plate 8 can be essentially planar and essentially lie in the xy-plane. In other examples, however, the metal plate 8 does not necessarily have to be flat, but can, for example, be curved at least partially in the direction of the conductor 2.

[0015] The metal plate 8 can be designed to influence or change the magnetic field 10 generated by a measuring current. In this context, it should be noted that such an influence of the metal plate 8 on the magnetic field 10 in the Fig. 1A, or in the field lines of the magnetic field 10, is not considered or shown for the sake of simplicity. The influence of the metal plate 8 on the magnetic field 10 can decrease with increasing distance from the metal plate 8. Since the first sensor element 12A can be located closer to the metal plate 8 than the second sensor element 12B, the influence of the metal plate 8 on a measurement of the first sensor element 12A can be stronger than on a measurement of the second sensor element 12B. If the second sensor element 12B is sufficiently far from the metal plate 8, the influence of the metal plate 8 on the measurement of the second sensor element 12B can even be negligible. As a result, the metal plate 8 can introduce a certain asymmetry into the measurements or measurement results of the two sensor elements 12A and 12B. This can reduce a phase error in the measured magnetic field strength, as discussed further below in connection with the Fig. 2A and Fig. 2B is being discussed.

[0016] The sensor device 100 can include further components. In the example shown, the conductor 2 and the metal plate 8 can be encapsulated in a first encapsulation material 14. The magnetic field sensor chip 4 can be arranged outside the first encapsulation material 14. The magnetic field sensor chip 4 can be encapsulated in a second encapsulation material 16, with the conductor 2 and the metal plate 8 also being arranged outside the second encapsulation material 16. In this case, the conductor 2 can therefore be an external conductor located outside the housing formed by the second encapsulation material 16. Alternatively, in other examples, the metal plate 8, the conductor 2, and the magnetic field sensor chip 4 can be encapsulated in a common encapsulation material.

[0017] In a non-restrictive example, one or both of the encapsulation materials 14 and 16 can be an epoxy resin, which may be manufactured by a suitable molding process. The encapsulation materials 14 and 16 can be the same or different from each other. The first encapsulation material 14 can have a recess 18, in which the magnetic field sensor chip 4 or the second encapsulation material 16 with the magnetic field sensor chip 4 encapsulated therein can be arranged in the recess 18. A distance h from the top of the second encapsulation material 16 to the bottom of the metal plate 8 can, in a non-restrictive example, be in the range of approximately 0.1 mm to approximately 2.6 mm (for example, approximately 2.5 mm).

[0018] In the example shown, the magnetic field sensor chip 4 can be mounted on a first circuit board (or PCB) 20. The circuit board 20 can be oriented perpendicular to the current conductor 2. The first circuit board 20 can also be encapsulated in the second encapsulation material 16. The housing formed by the second encapsulation material 16 can be arranged on a second circuit board 22, which could, for example, be a gate driver PCB. The magnetic field sensor chip 4 can be electrically connected to the second circuit board 22 via the first circuit board 20 and pins 24. Mounting elements 26, which can also function as spacers, can be arranged between the underside of the first encapsulation material 14 and the top side of the second circuit board 22.

[0019] As explained above, the strength By of the y-component of the magnetic field 10 can be detected or measured by the magnetic field sensor chip 4. Fig. Figure 2A shows in this context a dependence of the magnetic field strength By on the frequency of the electric current carried through the conductor 2 for a first case of a sensor device according to the disclosure with a metal plate 8 (see "with metal plate") and a second case of a conventional sensor device without a metal plate (see "without metal plate"). Here, the magnetic field strength By in percent (relative to the initial value at 0 Hz) is plotted against the frequency in Hz. Fig. Figure 2B shows, for the two cases mentioned, with and without metal plate 8, a dependence of the phase of the magnetic field strength By (in degrees) on the frequency of the electric current carried through the conductor 2 (in Hz). From the data in the Fig. The frequency responses shown in Figure 2B demonstrate that a phase error in a sensor device according to the disclosure can be smaller than in a conventional sensor device. Sensor devices according to the disclosure can therefore provide an improved frequency response. Typical frequencies can, in one example, be in the range of approximately 0 kHz to approximately 2 kHz. In this context, the Fig. 2A and Fig. 2B each represents an exemplary typical frequency value of approximately 2kHz.

[0020] In conventional sensor devices, the frequency response can be optimized by reducing the busbar width in the sensor area (e.g., by forming lateral tapers in the conductor). However, the disadvantage of this principle is that the reduced conductor cross-section can lead to higher power dissipation in the sensor area, potentially causing overheating. In contrast, sensor devices according to the disclosure can achieve a suitable improvement in the frequency response as described without reducing the conductor cross-section. This allows for improved thermal flux through the conductor as well as improved mechanical stability of the conductor. Furthermore, sensor devices according to the disclosure can be coreless and do not require a magnetic field concentrator.The sensor devices can be coreless current sensors that can be integrated into an external busbar.

[0021] Fig. Figure 3 shows a method for manufacturing a sensor device according to the disclosure. The method is presented in a general form and can, for example, be used to manufacture the sensor device 100 of the Fig. 1. The process can be extended to include one or more aspects, which are described in connection with other examples discussed herein. The order of the individual process steps can be changed as long as this is technically feasible.

[0022] In step 28, a conductor 2 designed to carry an electric current can be arranged. In a further step 30, a metal plate 8 can be arranged above the conductor 2. In a further step 32, a differential magnetic field sensor chip 4 can be arranged in an opening 6 of the conductor 2 below the metal plate 8. The magnetic field sensor chip 4 can be designed to detect a magnetic field 10 generated by the electric current.

[0023] In a first example, in further optional steps, the conductor 2 and the metal plate 8 can be encapsulated in a first encapsulation material 14, and the magnetic field sensor chip 4 can be arranged in a recess 18 of the first encapsulation material 14. In a second example, in a further optional step, the metal plate 8, the conductor 2, and the magnetic field sensor chip 4 can be encapsulated in a common encapsulation material. Examples

[0024] The following describes sensor devices according to the disclosure and associated manufacturing processes by means of examples.

[0025] Example 1 is a sensor device comprising: a current conductor designed to carry an electric current; a differential magnetic field sensor chip arranged in an opening of the current conductor and designed to detect a magnetic field generated by the electric current; and a metal plate arranged over the current conductor and over the magnetic field sensor chip.

[0026] Example 2 is a sensor device according to Example 1, wherein: the current conductor runs in a first direction in a neighborhood of the opening, the magnetic field sensor chip comprises two sensor elements spaced apart in a second direction perpendicular to the first direction, and the two sensor elements are sensitive in a third direction perpendicular to the first direction and perpendicular to the second direction.

[0027] Example 3 is a sensor device according to Example 1 or 2, wherein a first sensor element of the magnetic field sensor chip is arranged closer to the metal plate than a second sensor element of the magnetic field sensor chip.

[0028] Example 4 is a sensor device according to one of the preceding examples, wherein the sensor elements of the magnetic field sensor chip are arranged offset from a center of the opening.

[0029] Example 5 is a sensor device according to one of the preceding examples, wherein the metal plate and the current conductor are encapsulated in a first encapsulation material.

[0030] Example 6 is a sensor device according to Example 5, wherein the magnetic field sensor chip is arranged outside the first encapsulation material.

[0031] Example 7 is a sensor device according to Example 5 or 6, wherein the first encapsulation material has a recess and the magnetic field sensor chip is arranged in the recess.

[0032] Example 8 is a sensor device according to one of the preceding examples, wherein the magnetic field sensor chip is encapsulated in a second encapsulation material and the current conductor is arranged outside the second encapsulation material.

[0033] Example 9 is a sensor device according to one of Examples 1 to 4, wherein the metal plate, the current conductor and the magnetic field sensor chip are encapsulated in a common encapsulation material.

[0034] Example 10 is a sensor device according to one of the preceding examples, wherein the magnetic field sensor chip is mounted on a circuit board and the circuit board runs perpendicular to the current conductor.

[0035] Example 11 is a sensor device according to one of Examples 2 to 10, wherein the current conductor in the vicinity of the opening has a constant dimension in the third direction.

[0036] Example 12 is a sensor device according to any of Examples 2 to 11, wherein a dimension of the metal plate in the third direction is larger than a dimension of the current conductor in the third direction.

[0037] Example 13 is a sensor device according to one of Examples 2 to 12, wherein a dimension of the metal plate in the third direction is larger than a dimension of the metal plate in the first direction.

[0038] Example 14 is a sensor device according to one of the preceding examples, wherein the metal plate has no openings.

[0039] Example 15 is a sensor device according to one of the preceding examples, wherein the metal plate runs parallel to the current conductor.

[0040] Example 16 is a sensor device according to one of Examples 1 to 14, wherein the metal plate is bent at least partially in the direction of the current conductor.

[0041] Example 17 is a sensor device according to one of the preceding examples, wherein the metal plate is made of at least one of copper, aluminium or alloys thereof.

[0042] Example 18 is a sensor device according to one of the preceding examples, wherein the sensor device is coreless and does not have a magnetic field concentrator.

[0043] Example 19 is a method for manufacturing a sensor device, the method comprising: arranging a current conductor designed to carry an electric current; arranging a metal plate over the current conductor; and arranging a differential magnetic field sensor chip in an opening of the current conductor below the metal plate, the magnetic field sensor chip being designed to detect a magnetic field generated by the electric current.

[0044] Example 20 is a version of Example 19, further comprising: encapsulating the current conductor and the metal plate in a first encapsulation material; and arranging the magnetic field sensor chip in a recess of the first encapsulation material.

[0045] Example 21 is a method according to Example 19, further comprising: encapsulating the metal plate, the current conductor and the magnetic field sensor chip in a common encapsulation material.

[0046] It should be noted that the description and drawings merely illustrate the principles of the proposed methods and devices. A person skilled in the art will be able to implement various arrangements which, although not explicitly described or shown here, embody the principles of the invention and are included within its scope. Furthermore, all examples and embodiments outlined in this document are, in principle and expressly, intended only for explanatory purposes to help the reader understand the principles of the proposed methods and devices. Moreover, all statements in this document that describe principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to include their equivalents.

Claims

[1] Sensor device comprising: a conductor (2) designed to carry an electric current; a differential magnetic field sensor chip (4) arranged in an opening (6) of the current conductor (2) and designed to detect a magnetic field (10) generated by the electric current; and a metal plate (8) arranged above the current conductor (2) and above the magnetic field sensor chip (4), wherein the metal plate (8) and the current conductor (2) are encapsulated in a first encapsulation material (14) and the magnetic field sensor chip (4) is arranged outside the first encapsulation material (14), wherein the magnetic field sensor chip (4) is encapsulated in a second encapsulation material (16) and the current conductor (2) is arranged outside the second encapsulation material (16), wherein the first encapsulation material (14) has a recess (18) and the second encapsulation material (16) with the magnetic field sensor chip (4) encapsulated therein is arranged in the recess (18). [2] Sensor device according to claim 1, wherein: the conductor (2) runs in a first direction in the vicinity of the opening (6), the magnetic field sensor chip (4) comprises two sensor elements (12A, 12B) spaced apart in a second direction perpendicular to the first direction, and the two sensor elements (12A, 12B) are sensitive in a third direction perpendicular to the first direction and perpendicular to the second direction. [3] Sensor device according to claim 1 or 2, wherein a first sensor element (12A) of the magnetic field sensor chip (4) is arranged closer to the metal plate (8) than a second sensor element (12B) of the magnetic field sensor chip (4). [4] Sensor device according to one of the preceding claims, wherein the sensor elements (12A, 12B) of the magnetic field sensor chip (4) are arranged offset from a center of the opening (6). [5] Sensor device according to one of the preceding claims, wherein the magnetic field sensor chip (4) is mounted on a circuit board (20) and the circuit board (20) is perpendicular to the current conductor (2). [6] Sensor device according to one of claims 2 to 5, wherein the current conductor (2) in the vicinity of the opening (6) has a constant dimension in the third direction. [7] Sensor device according to any one of claims 2 to 6, wherein a dimension of the metal plate (8) in the third direction is larger than a dimension of the conductor (2) in the third direction. [8] Sensor device according to any one of claims 2 to 7, wherein a dimension of the metal plate (8) in the third direction is larger than a dimension of the metal plate (8) in the first direction. [9] Sensor device according to one of the preceding claims, wherein the metal plate (8) has no openings. [10] Sensor device according to one of the preceding claims, wherein the metal plate (8) runs parallel to the current conductor (2). [11] Sensor device according to one of claims 1 to 9, wherein the metal plate (8) is bent at least partially in the direction of the current conductor (2). [12] Sensor device according to one of the preceding claims, wherein the metal plate (8) is made of at least one of copper, aluminium or alloys thereof. [13] Sensor device according to one of the preceding claims, wherein the sensor device is coreless and does not have a magnetic field concentrator.

Images