Current measuring device and associated production method

Abstract

The invention relates to a current measuring device for measuring an electrical current (I). The current measuring device firstly comprises a current measuring resistor (1) comprising: two connection parts (2, 3) made of a conductor material; and a resistor element (4) made of a resistive material. The current measuring device further comprise a printed circuit board (7) which is electrically connected to the two connection parts (2, 3) of the current measuring resistor (1) at at least two connecting points. According to the invention, the connection parts (2, 3) of the current measuring resistor (1) are each connected to the printed circuit board (7) at the connecting points by an integral press-fit. The invention also relates to a corresponding production method.

Description

[0001] DESCRIPTION

[0002] Current measuring device and associated manufacturing process

[0003] Area of

[0004] The invention relates to a current measuring device for measuring an electric current using the four-wire technique, comprising a low-ohm current measuring resistor and a circuit board connected to the current measuring resistor. Furthermore, the invention relates to a corresponding manufacturing method for producing such a current measuring device.

[0005] Hi the

[0006] It is known from the prior art (e.g., EP 0 605 800 B1) to measure an electric current using the four-wire technique. In this technique, the electric current to be measured is passed through a low-ohm current measuring resistor ("shunt"), and the voltage drop across the current measuring resistor is measured. According to Ohm's law, the measured voltage then provides a measure of the electric current flowing through the low-ohm current measuring resistor.

[0007] It is also known from the prior art to permanently connect a printed circuit board (PCB) to the current measuring resistor, with a measuring circuit arranged on the PCB that measures the voltage drop across the low-ohm current measuring resistor. For example, the measuring circuit can be an application-specific integrated circuit (ASIC), as is known, for example, from EP 1 363 131 A1.

[0008] Firstly, the circuit board with the measuring circuit must be electrically connected to the current measuring resistor in order to measure the voltage drop across the resistance element of the low-ohm current measuring resistor. This electrical connection can be made, for example, by soldering. Secondly, the circuit board with the measuring circuit must also be mechanically connected to the current measuring resistor, which is typically done differently to achieve the required mechanical strength of the mechanical connection.

[0009] A disadvantage of the known current measuring device described above is the connection between the circuit board and the current measuring resistor, which is not yet entirely satisfactory. For example, the solder connections between the circuit board and the current measuring resistor are relatively large, which makes precise voltage measurement at the terminals of the current measuring resistor difficult.

[0010] Furthermore, with regard to the general technical background of the invention, reference should be made to DE 10 2010 010 152 Ul, DE 10 2020 003 458 Al and DE 10 2006 019 895 Al.

[0011] Description of the invention

[0012] The invention is therefore based on the object of creating a correspondingly improved current measuring device and a corresponding manufacturing method therefor.

[0013] This object is achieved by a current measuring device according to the invention according to the main claim or by a corresponding manufacturing method according to the secondary claim.

[0014] The current measuring device according to the invention serves to measure an electric current and, in accordance with the known current measuring device described at the outset, initially has a low-ohm current measuring resistor.

[0015] In accordance with the known current measuring resistor described at the beginning, the current measuring resistor has two connection parts made of a conductor material (e.g. copper) in order to introduce the electrical current to be measured into the current measuring resistor or to lead it out of the current measuring resistor.

[0016] A low-ohm resistor element made of a low-ohm resistor material (e.g., Manganin®) is arranged in the direction of current flow between the two connecting parts. The resistor element is made of a low-ohm resistor material (e.g., Manganin®) and is passed through by the electrical current to be measured during a measurement. Such current-sensing resistors are known from the prior art (e.g., EP 0 605 800 B1). It should be noted that the invention is not limited to copper with regard to the conductor material of the connecting parts, but can also be implemented using a copper alloy, aluminum, or an aluminum alloy as the conductor materials.

[0017] Furthermore, it should be noted that the invention is not limited to Manganin® as a resistor material. Thus, the invention can also be implemented with other resistor alloys, as will be described in detail below.

[0018] Furthermore, the current measuring device according to the invention, in accordance with the known current measuring device described at the outset, has a printed circuit board which is connected to the two connection parts of the current measuring resistor at at least two connection points.

[0019] The current measuring device according to the invention is characterized in that the connection between the circuit board on the one hand and the current measuring resistor on the other hand is made by a press connection, which creates a material connection between the circuit board and the current measuring resistor.

[0020] In one variant of the invention, the press connection is a press-sintered connection. Such press-sintered connections are known per se from the prior art and therefore need not be described in detail. It should only be mentioned here that the press-sintered connection can optionally contain an additional sintered material, such as silver or copper.

[0021] In another variant of the invention, however, the press connection is a press-bonded connection, which may, for example, contain an epoxy adhesive as an adhesive.

[0022] In both variants (press-sintered joint and press-bonded joint), the joining partners (connecting parts of the current measuring resistor and / or circuit board) can have a surface structure at the connection points, for example, a nanostructure. The surface structure can include material elevations on the surface of the joining partners, which are subjected to pressure during the pressing process and then create the desired press connection locally at these points. While the space between the material elevations is not pressed, thus no press connection is created at these points. This surface structure makes it possible to limit the spatial extent of the press connection, which enables precise stress measurement at the connecting parts.For example, the individual compression connections can each have a horizontal extension parallel to the circuit board of a maximum of 1 mm, 500 pm, 250 pm or 100 pm, which enables precise voltage measurement at the connection parts.

[0023] Furthermore, it should be noted that the surface structuring may contain one or more of the following materials:

[0024] • ENIG (“Electroless Nickel Immersion Gold”),

[0025] • ENEPIG (“Electroless Nickel Electroless Palladium Immersion Gold”),

[0026] • Gold,

[0027] • Copper,

[0028] • Nickel-phosphorus,

[0029] • Silver.

[0030] The aforementioned press connection according to the invention between the circuit board and the current measuring resistor establishes both a mechanical connection and an electrical connection in practice. In this case, it is possible to electrically decouple the mechanical connection from the electrical connection. For example, this can be achieved through the aforementioned surface structuring with material elevations on the surface of the joining partners (circuit board and connection parts of the current measuring resistor). Thus, the press connection is then only established in the area of ​​the material elevations. The material elevations can then be spatially separated from one another, with one material elevation establishing the mechanical connection, while another material elevation establishes the electrical connection.

[0031] In a preferred embodiment of the invention, the circuit board for contacting the current measuring resistor has a plurality of contact fingers that protrude from the circuit board.

[0032] For example, these contact fingers can be manufactured by cutting slots into the side of the circuit board, which then separate the contact fingers from each other. Therefore, the contact fingers preferably protrude from the circuit board in the same direction and parallel to each other.

[0033] The contact fingers on the circuit board can then contact the current-sense resistor on its top and / or bottom. It should be noted that the current-sense resistor can have recesses ("recesses") into which one of the circuit board's contact fingers can protrude. In the area of ​​these recesses, the current-sense resistor then has a reduced thickness compared to the rest of the current-sense resistor. By adjusting the depth of the recesses, the temperature coefficient of resistance (TCR) of the current-sense resistor's resistance value can also be adjusted.

[0034] In one embodiment of the invention, each of the two terminals of the current-sensing resistor contains a recess for one of the printed circuit board's contact fingers. These recesses preferably border the resistor element, but it is also possible for the recesses to extend into the resistor element. Furthermore, it should be noted that the recesses in the terminals of the current-sensing resistor preferably extend from a side edge of the current-sensing resistor, so that the contact fingers of the printed circuit board can be aligned at right angles to the current-sensing resistor and extend from the side into the recesses in the terminals of the current-sensing resistor.

[0035] Furthermore, within the scope of the invention, it is also possible for the resistance element of the current measuring resistor to also include a recess for one of the contact fingers of the circuit board, with this recess preferably being located on the same side edge of the current measuring resistor as the recesses in the connection parts of the current measuring resistor. One of the contact fingers of the circuit board then protrudes into the recesses in the resistance element, enabling a center tap. It should be noted, however, that the center tap on the resistance element is merely optional.

[0036] Furthermore, it is possible that at least one of the contact fingers of the circuit board contacts the current measuring resistor on its underside, while the other contact fingers can contact the current measuring resistor on its top side.

[0037] In the preferred embodiment of the invention, the circuit board is equipped with at least one electrical or electronic component. This component can also be connected to the circuit board by a press connection, in particular by a press-sintered connection or a press-bonded connection. The inventive concept of a press connection is therefore not limited to the connection between the circuit board and the current measuring resistor, but can also be used for the connection between the circuit board and the components located thereon.

[0038] For example, the circuit board can be equipped with at least one of the following components:

[0039] • Analog-digital converter,

[0040] • Module for isolated data transmission,

[0041] • Microprocessor,

[0042] • Interface for transmitting measured values ​​to an external evaluation unit.

[0043] Regarding the microprocessor, it should be mentioned that it can be arranged either on the high side or on the low side of the component for potential-isolated data transmission.

[0044] As already mentioned at the beginning, the current measuring device according to the invention enables current measurement using the four-wire technique. Here, the voltage drop across the resistance element of the current measuring resistor is measured at two connection points on the connection parts of the current measuring resistor. From the voltage measured across the resistance element in this way, the current flowing through the current measuring resistor can then be calculated according to Ohm's law. Within the scope of the invention, this voltage can also be measured at more than two connection points. For example, the circuit board can be connected to the two connection parts of the current measuring resistor at at least four connection points in order to measure the voltage drop across the resistance element at multiple locations.For example, the four connection points can form a rectangle, whereby the connection points can each form several measuring channels in pairs, whereby the measuring channels each measure the voltage between the two connection parts of the current measuring resistor.

[0045] The connection points of the two measuring channels can be arranged crosswise, as is known, for example, from DE 10 2021 103 241.5. Alternatively, it is possible for the connection points of the two measuring channels to be arranged in parallel, as is known, for example, from WO 2014 / 161624 A1.

[0046] In a simple embodiment of the invention, however, the circuit board is connected to the two terminals of the current measuring resistor at only two connection points in order to measure the voltage drop across the resistance element of the current measuring resistor. A center tap can optionally be provided by also connecting the circuit board to the resistance element. In another variant, up to three connection points can be provided to connect the circuit board to the terminals, with the three connection points forming a closed voltage loop.

[0047] Furthermore, it should be mentioned that the circuit board can also contain an interface in order to transmit measured values ​​of the voltages dropping between the connection parts and / or measured values ​​of a temperature sensor arranged on the circuit board to an external evaluation unit via the interface, wherein the interface is preferably an analog interface.

[0048] Alternatively, within the scope of the invention, it is possible for the circuit board to carry an evaluation unit that calculates the electrical current flowing through the current measuring resistor from the measured values ​​of the voltage drop between the connection parts. The evaluation unit can optionally be connected to a temperature sensor on the circuit board and, when calculating the current flowing through the current measuring resistor, takes the temperature into account for temperature correction. The circuit board can optionally also have a digital interface that is connected to the evaluation unit on the circuit board in order to output the electrical current calculated by the evaluation unit. Furthermore, the actual measured values ​​of the measured voltage and the measured temperature can also be transmitted via the digital interface.

[0049] Within the scope of the invention, the circuit board can be a rigid circuit board, as is known per se from the prior art. Such circuit boards can be made of, for example, fiberglass composite material. In a preferred embodiment of the invention, however, the circuit board is a flexible printed circuit board (FPC). Furthermore, a hybrid circuit board that is partially flexible and partially rigid is also possible; such circuit boards are also referred to as rigid-flex circuit boards.

[0050] Furthermore, it should be mentioned that the current measuring resistor is preferably low-ohmic with an electrical resistance of at most 10 pQ, 25 pQ, 50 pQ, 100 pQ, 200 pQ or 500 pQ.

[0051] Furthermore, the current measuring resistor can have a current rating of at least 100 A, 200 A, 500 A, 1 kA, 2 kA, or 5 kA. It should also be noted in general that the terminals of the current measuring resistor, the resistance element of the current measuring resistor, or the current measuring resistor as a whole are preferably plate-shaped, in particular flat or curved.

[0052] Within the scope of the invention, the resistance element of the current measuring resistor can have a smaller thickness than the connection parts of the current measuring resistor.

[0053] Furthermore, it should be noted that in the current measuring resistor, the resistance element can be connected to the connecting parts by a welded joint, in particular by electron beam welding.

[0054] The invention further enables the current measuring resistor to have an electrical resistance value with a temperature coefficient of at most 200 ppm / K, 100 ppm / K, 50 ppm / K, 20 ppm / K or 10 ppm / K.

[0055] It should also be mentioned that the conductor material of the connection parts of the current measuring resistor can be copper, a copper alloy, aluminum or an aluminum alloy.

[0056] For example, the resistance material of the resistance element of the current measuring resistor can be one of the following alloys:

[0057] • a copper alloy, in particular a copper-manganese alloy, in particular CuMnl2Ni2 or CuMn7Sn2.3, or a copper-manganese-nickel alloy, in particular Cu84Ni4Mnl2 or Cu65Mn25NilO, or a copper-chromium alloy,

[0058] • a nickel alloy, in particular NiCr or CuNi.

[0059] However, the conductor material of the connection parts of the current measuring resistor should have a lower specific electrical resistance than the resistance material of the resistance element of the current measuring resistor.

[0060] Furthermore, it should be noted that the current measuring resistor preferably has a length that lies in the range of 5 mm - 200 mm along the main current flow direction. The width of the current measuring resistor transverse to the main current flow direction, however, is preferably in the range of 10 mm - 100 mm, while the current measuring resistor preferably has a thickness that lies in the range of 1 mm - 5 mm. Regarding the press connections according to the invention, it should also be mentioned that they can have a very low electrical contact resistance, which is preferably less than 1 pΩ / mm 2 .

[0061] In addition to the current measuring device according to the invention described above, the invention also claims protection for a corresponding manufacturing method, wherein the individual method steps of the manufacturing method according to the invention already emerge from the above description of the current measuring device according to the invention and therefore do not need to be described separately again.

[0062] It should only be mentioned that during the press-sintering process, heat is preferably applied to the connection points to heat them to a sintering temperature. This sintering temperature is preferably below the melting temperature of the conductor material and also below the melting temperature of the resistor material. The sintering temperature can therefore range, for example, from 100 °C to 500 °C.

[0063] In the press-bonded joint according to the invention, however, there is preferably no heat input.

[0064] Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred embodiments of the invention with reference to the figures.

[0065] Brief description of the drawings

[0066] Figure 1A shows a perspective view of a current measuring device according to the invention with a current measuring resistor, a flexible printed circuit board and an interface with a plug connection.

[0067] Figure 1B shows the current measuring device from Figure 1A with a press die for creating a press connection between the circuit board and the current measuring resistor.

[0068] Figure 1C shows a detailed view of Figure 1A.

[0069] Figure 2 shows a schematic side view of a current measuring resistor according to the invention during a pressing process. Figure 3 shows a modification of Figure 2.

[0070] Figure 4 shows a schematic representation of a current measuring resistor according to the invention in a press-bonded connection.

[0071] Figure 5 shows a modification of Figure 3.

[0072] Figure 6 shows a plan view of another embodiment of a current measuring device according to the invention.

[0073] Figure 7 shows a modification of Figure 6, with additional components mounted on the circuit board.

[0074] Figure 8 shows a modification of Figure 7.

[0075] Figure 9 shows a modification of Figure 1A, where the current measuring resistor is contacted at the top and bottom.

[0076] Figure 10 shows a schematic detailed view of a current measuring resistor according to the invention with recesses in the area of ​​the connection parts for contact fingers of the printed circuit board.

[0077] Figure 11 shows a schematic plan view of a current measuring resistor according to the invention with press connections for an electrical connection and press connections decoupled therefrom for a mechanical connection.

[0078] Figure 12 shows a diagram illustrating the temperature coefficient of the electrical resistance value as a function of the depth of the depressions (recesses).

[0079] Figure 13 shows a schematic representation of a current measuring resistor according to the invention with two parallel measuring channels.

[0080] Figure 14 shows a modification of Figure 13, with the measuring points of the two measuring channels arranged crosswise. Figure 15 shows a perspective view of a current measuring resistor according to the invention with two voltage taps on the connecting parts and a center tap on the resistance element.

[0081] Figure 16 shows a modification of Figure 15 with recesses at the respective connection points.

[0082] Figure 17 shows a modification of Figure 11 with an additional center tap on the resistance element.

[0083] Figure 18 shows a modification of Figure 1C, where the current measuring resistor is contacted at the bottom and at the top by contact fingers.

[0084] Figure 19 shows a plan view of the embodiment according to Figure 18.

[0085] Figure 20 shows an embodiment in which the contact fingers of the circuit board extend over the entire width of the current measuring resistor in order to enable voltage measurement at different points.

[0086] Figure 21 shows a flow chart to illustrate the manufacturing method according to the invention for creating a press-sintered connection.

[0087] Figure 22 shows a flow chart to illustrate the manufacturing method according to the invention for producing a press-bonded joint.

[0088] Detailed description of the drawings

[0089] The embodiment of a current measuring device according to the invention, which is shown in Figures 1A-1C, will now be described.

[0090] The invention initially comprises a low-ohmic current measuring resistor 1, which consists of two connection parts 2, 3 made of a conductor material (e.g. copper) and a resistance element 4 made of a resistance material (e.g. Manganin®), wherein the resistance element 4 is arranged between the two connection parts 2, 3 in the direction of current flow. The electrical current I to be measured is introduced into the current measuring resistor 1 via the connection part 2 and discharged from the current measuring resistor 1 via the connection part 3. The voltage drop across the resistance element 4 is then, according to Ohm's law, a measure of the electrical current I flowing through the current measuring resistor 1.

[0091] In each of the two connecting parts 1, 3, a bore 5 or 6 is arranged, which serves to contact the two connecting parts 1, 3, as is known per se from the prior art and is also described, for example, in EP 0 605 800 B1.

[0092] In addition, the current measuring device according to the invention has a printed circuit board 7, which in this embodiment is a flexible printed circuit board (FPC: Flexible Printed Circuit).

[0093] The circuit board 7 is connected to an interface 8, which serves to output measured values ​​of the electrical voltage drop across the resistance element 4 of the current measuring resistor 1 to an external evaluation unit. For this purpose, the interface 8 enables a plug-in connection, as is known per se from the prior art.

[0094] For electrical contacting of the current measuring resistor 1, the circuit board 7 has several contact fingers 9-11. Contact finger 9 serves to electrically contact the connection part 2, while contact finger 11 serves to electrically contact the other connection part 3. The middle contact finger 10, on the other hand, serves to electrically contact the resistance element 4 and thus enables a center tap.

[0095] The contact fingers 9-11 protrude from the same side of the circuit board 7 and extend in the same direction. For example, the contact fingers 9-11 can be manufactured by inserting slots into the circuit board 7.

[0096] In the connection part 2 there is a recess 12 for receiving the contact finger 9. In the other connection part 3 there is also a corresponding recess 13 for receiving the other contact finger 11. The two recesses 12, 13 originate from the same side edge of the current measuring resistor 1 and are directly adjacent to the resistance element 4. However, it should be mentioned that alternatively there is also the possibility for the two recesses 12, 13 to extend into the resistance element 4. In the area of ​​the recesses 12, 13, the two connection parts 2, 3 have a reduced thickness. It should be mentioned here that the temperature coefficient (TCR) of the resistance value of the current measuring resistor 1 can be adjusted by reducing the thickness in the area of ​​the recesses 12, 13, as will be described below.

[0097] It should also be noted that the contact fingers 9-11 each contact the connection parts 2, 3 and the resistance element 4 on their upper sides. This means that the contact finger 10 rests on the upper side of the resistance element 4, while the other contact fingers 9, 11 rest on the upper side of the connection parts 2, 3 in the area of ​​the recesses 12, 13.

[0098] When electrically contacting the current measuring resistor 1 through the circuit board 7, the contact fingers 9-11 are initially positioned in the position shown in Figure 1A.

[0099] A press connection is then created by placing a press die 14 onto the ends of the contact fingers 9-11 and then applying a pressing force to the ends of the contact fingers 9-11. The pressing force is so great that a materially bonded press connection is created between the contact fingers 9-11 on the one hand and the connection parts 2, 3 or the resistance element 4 on the other. This press connection can be either a press-bonded connection or a press-sintered connection, as will be described in detail below.

[0100] The schematic representations according to Figures 2-5 will now be described, which largely correspond to the embodiment described above and shown in Figures 1A-1C, so that in order to avoid repetition, reference is made to the above description, the same reference numerals being used for corresponding details.

[0101] It can be seen from the illustrations that the connecting parts 2, 3 are connected to the resistance element 4 by a weld seam 15, as is also known, for example, from EP 0 605 800 B1.

[0102] Furthermore, the drawings show not only the upper pressing punch 14, but also a lower pressing punch 16, so that a pressing force is exerted from both above and below when producing the press connection.

[0103] In the variants of the invention shown in Figures 2 and 3, the press connection is a press-sintered connection. Heat is introduced during the pressing process to enable the sintering process.

[0104] In the variant of the invention according to Figure 2, three connection areas 17-19 are shown, all of which are arranged on the top side of the current measuring resistor 1.

[0105] In the variant of the invention according to Figure 3, however, three additional connecting areas 20-22 are provided, all of which are arranged on the underside of the current measuring resistor.

[0106] The embodiment shown in Figure 4 is largely identical to the embodiment shown in Figure 2. However, the press connection is made without heat input, using a press-and-adhesive connection. Therefore, an epoxy adhesive is applied under the connection areas 17-19.

[0107] The embodiment shown in Figure 5 is largely identical to the embodiment shown in Figure 3. However, this one also does not use a press-sintered joint, but rather a press-bonded joint without heat input. Therefore, an epoxy adhesive is located under the connecting areas 17-22, as is also the case in the embodiment shown in Figure 4.

[0108] The embodiment according to Figure 6 again partially corresponds to the embodiments described above, so that in order to avoid repetition, reference is made to the above description, the same reference numerals being used for corresponding details.

[0109] A special feature of this embodiment is that a temperature sensor 23 is additionally arranged on the circuit board 7, which measures the temperature at the resistance element 4. This makes it possible to take into account the temperature dependence of the resistance value of the resistance element 4 when calculating the current I flowing through the current measuring resistor 1 from the measured voltage, which allows for temperature compensation.

[0110] The embodiment according to Figure 7 again largely corresponds to the embodiments described above, so that in order to avoid repetition, reference is made to the above description, the same reference numerals being used for corresponding details.

[0111] A special feature of this embodiment is that several additional electronic components are arranged on the circuit board 7, namely an analog / digital converter 24, a microprocessor 25, and a module 26 with an isolation gap 27 for electrically isolated data transmission. The module 26 for electrically isolated data transmission is located between the microprocessor 25 and the interface 8.

[0112] The embodiment according to Figure 8 largely corresponds to the embodiment described above and shown in Figure 7, so that in order to avoid repetition, reference is made to the above description and the same reference numerals are used.

[0113] A special feature of this embodiment is that the module 26 for potential-isolated data transmission is located between the analog / digital converter 24 and the microprocessor 25.

[0114] Figure 9 shows a perspective view of the embodiment according to Figures 6-8, so that in order to avoid repetition, reference is made to the above description.

[0115] Figure 10 shows a perspective detailed view of the current measuring resistor according to the invention in the area of ​​the recesses 12, 13.

[0116] This shows that the connecting parts 2, 3 each have a specific thickness dA, while the resistance element 4 has a reduced thickness dW. In the area of ​​the recesses 12, 13, the thickness of the connecting parts 2, 3 is reduced, with the recesses 12, 13 having a depth dV. By adjusting the recess dV, the temperature coefficient TCR of the current measuring resistor 1 can also be adjusted.

[0117] Figure 11 shows a schematic representation of a current measuring resistor 1 according to the invention in a plan view.

[0118] In this case, each recess 12, 13 contains a mechanical connection area 28, 29, which serves solely for the mechanical connection between the circuit board 7 and the current measuring resistor 1. Therefore, in the mechanical connection areas 28, 29, the surface of the joining partners has a material elevation, which is subjected to compression during the press connection and thus creates a press connection, with this material elevation being electrically decoupled. Furthermore, each recess 12, 13 contains an electrical connection area 30, 31 for establishing an electrical connection.

[0119] It should be noted that the mechanical connection areas 28, 29 on the one hand and the electrical connection areas 30, 31 on the other hand are spatially separated and electrically decoupled.

[0120] Finally, Figure 12 shows a diagram to illustrate the temperature coefficient TCR as a function of the depth dZ of the recesses 12, 13 in the connection parts 2, 3 of the current measuring resistor 1. It is clearly visible from the diagram that the temperature coefficient TCR can be adjusted by adjusting the depth dZ of the recesses 12, 13.

[0121] Figures 13 and 14 show two variants of the invention, each with four electrical connection areas 30.1, 30.2, 31.1, 31.2, which form two measuring channels in pairs.

[0122] In the invention variant according to Figure 13, the measuring channels are arranged in parallel, as is known, for example, from WO 2014 / 161624 A1. In the invention variant according to Figure 14, however, the measuring channels are arranged crosswise, as is known, for example, from DE 10 2021 103 241.5.

[0123] Figures 15 and 16 again show perspective views of different variants of the invention without the recesses in the connecting parts (Figure 15) or with the recesses 12, 13 in the connecting parts 2, 3 (Figure 16).

[0124] Figure 17 shows a schematic representation corresponding to Figure 11 with an additional center tap, which comprises an electrical connection area 32 and a mechanical connection area 33.

[0125] Figures 18 and 19 show different views of a current measuring resistor 1 according to the invention with a total of six contact fingers 9-11, 34-36. The contact fingers 9-11 contact the current measuring resistor 1 on its upper side, while the other contact fingers 34-36 contact the current measuring resistor 1 on its underside.

[0126] Figure 20 shows a modification in which the contact fingers 9-11, 34-36 extend over the entire width of the current measuring resistor 1 and enable voltage measurement at different points.

[0127] The flow chart according to Figure 21 is now described below, which explains the variant of the invention with a press-sintered connection.

[0128] In a first step S1, a current measuring resistor with a resistance element and two connection parts is provided.

[0129] In a second step S2, the recesses described above are then formed in the connection parts and optionally in the resistance element of the current measuring resistor, which can be done, for example, by milling.

[0130] In the next step S3, a circuit board is then provided and in a step S4, contact fingers are formed in the circuit board, which are used to contact the current measuring resistor.

[0131] In the next step S5, the connection points of the current measuring resistor can then be nano-structured.

[0132] The current measuring resistor and the circuit board are then joined together in a step S6 such that the contact fingers of the circuit board lie in the recesses and / or on the back of the recesses.

[0133] In the next step S7, the connection points are then heated to a sintering temperature sufficient to produce a press-sintered connection.

[0134] In the next step S8, the circuit board and the current measuring resistor are then pressed together at the connection points to create the desired press-sintered connection.

[0135] Figure 22 shows a modification of Figure 21, so that reference can be made to the above description to avoid repetition. In contrast to the flow chart according to Figure 21, however, a press-bonded connection is made here instead of a press-sintered connection. Therefore, no heat is introduced during the pressing process. Instead, in step S6, an adhesive (e.g. epoxy adhesive) is applied to the connection points. The invention is not limited to the preferred embodiments described above. Rather, a multitude of variants and modifications are possible which likewise make use of the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and the features of the subclaims, independently of the respective claims referred to and in particular also without the features of the main claim.The invention therefore comprises various aspects of the invention which are protected independently of one another.

[0136] List of reference symbols

[0137] 1 current measuring resistor

[0138] 2 Connection part for introducing the current into the current measuring resistor

[0139] 3 Connection part for diverting the current from the current measuring resistor

[0140] 4 resistance element

[0141] 5 Hole in the connection part for introducing the current into the current measuring resistor

[0142] 6 Hole in the connection part for discharging the current from the current measuring resistor

[0143] 7 Circuit board

[0144] 8 Interface on the circuit board for outputting measured values

[0145] 9-11 Contact fingers of the circuit board

[0146] 12 Recess in the connection part for introducing the current into the current measuring resistor

[0147] 13 Recess in the connection part for discharging the current from the current measuring resistor

[0148] 14 pressing stamps for pressing from above

[0149] 15 Weld seam between the resistance element and the connecting parts

[0150] 16 press stamps for pressing from below

[0151] 17-22 Connection areas on the circuit board

[0152] 23 Temperature sensor on the circuit board

[0153] 24 analog / digital converters on the circuit board

[0154] 25 microprocessor

[0155] 26 Module for isolated data transmission

[0156] TI insulation distance

[0157] 28, 29 Mechanical connection area

[0158] 30, 31 Electrical connection area

[0159] 30.1 30.2 Electrical connection areas

[0160] 31.1, 31.2 Electrical connection areas

[0161] 32 Electrical connection area at the center tap

[0162] 33 Mechanical connection area at the center tap

[0163] 34-36 Contact fingers of the printed circuit board dW Thickness of the resistance element dA Thickness of the connection parts dV Depth of the recess in the connection parts dz Depth of the recess relative to the resistance element

[0164] I Current through the current measuring resistor

Claims

REQUIREMENTS 1. Current measuring device for measuring an electric current (I), comprising a) a current measuring resistor (1) with a) a first terminal part (2) made of a conductor material for introducing the electric current (I) to be measured into the current measuring resistor (1), a2) a second terminal part (3) made of a conductor material for introducing the electric current (I) to be measured out of the current measuring resistor (1), and a3) a resistance element (4) made of a resistance material, wherein the resistance element (4) is arranged in the direction of current flow between the first terminal part (2) and the second terminal part (3) so that the electric current (I) to be measured flows through the resistance element (4), and with b) a circuit board (7) which is connected at least at two connection points (30, 31; 30.1, 30.2, 31.1, 31.2) is electrically connected to the two connection parts (2, 3) of the current measuring resistor (1), characterized in that c) the connection parts (2, 3) of the current measuring resistor (1) are connected at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2) each by a press connection with a material-bonded connection to the circuit board (7).

2. Current measuring device according to claim 1, characterized in that a) the press connection is a press-sintered connection, b) the press-sintered connection optionally contains an additional sintered material, in particular silver or copper.

3. Current measuring device according to claim 1, characterized in that the press connection is a press-fit adhesive connection, in particular with an epoxy adhesive.

4. Current measuring device according to one of the preceding claims, characterized in that a) the connecting parts (2, 3) and / or the circuit board (7) have a surface structuring at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2), in particular a nano-structuring, b) that the surface structuring optionally contains at least one of the following materials: b) ENIG, b2) ENEPIG, b3) Gold, b4) Copper, b5) Nickel-Phosphorus, b6) Silver.

5. Current measuring device according to one of the preceding claims, characterized in that a) at least one of the press connections (28, 29) comprises a mechanical connection and an electrical connection between the circuit board (7) and the connection parts (2, 3) of the current measuring resistor (1), b) that the mechanical connection is spatially separated from the electrical connection (30, 31) and electrically insulated, in particular with a distance of at least 100 pm.

6. Current measuring device according to one of the preceding claims, characterized in that the press connections each have a horizontal extent parallel to the circuit board (7) of at most 1 mm, 500 pm, 250 pm or 100 pm in order to enable pinpoint voltage measurement at the connection parts (2, 3).

7. Current measuring device according to one of the preceding claims, characterized in that a) the circuit board (7) has several contact fingers (9-11; 34-36) for contacting the current measuring resistor (1), which project from the circuit board (7), in particular parallel to each other and in the same direction, and b) that the contact fingers (9-11; 34-36) of the circuit board (7) contact the current measuring resistor (1) on its top side and / or on its bottom side, and / or c) that the current measuring resistor (1) has recesses (12, 13) into which one of the contact fingers (9-11; 34-36) of the circuit board (7) projects, and / or d) that one of the contact fingers (9-11; 34-36) rests on the back side of the circuit board (7), wherein the current measuring resistor (1) in the area of ​​the recesses (12, 13) is raised relative to the rest of the current measuring resistor (1) has a reduced thickness, e) that the thickness of the connecting parts (2, 3) in the area of ​​the recesses (12, 13) is preferably smaller than the thickness of the resistive element (4).

8. Current measuring device according to claim 6, characterized in that a) at least one of the recesses (12, 13) for the contact fingers (9-11; 34-36) of the circuit board (7) is located in each of the connection parts (2, 3) of the current measuring resistor (1), preferably directly adjacent to the resistance element (4) and directly adjacent to a side edge of the first connection part (2), b) that the recesses (12, 13) in the connection parts (2, 3) optionally extend into the resistance element (4), c) that at least one of the recesses (12, 13) for the contact fingers (9-11; 34-36) of the circuit board (7) is located in the resistance element (4) of the current measuring resistor (1), preferably directly adjacent to the same side edge of the current measuring resistor (1), and / or d) that at least one of the contact fingers (9-11; 34-36) of the circuit board (7) are located on the underside of the current measuring resistor (1), opposite the recess.

9. Current measuring device according to one of the preceding claims, characterized in that a) the circuit board (7) is equipped with at least one electrical or electronic component (23-26), and b) the component (23-26) is connected to the circuit board (7) by a press connection, in particular by a press-sintered connection or by a press-fit adhesive connection, or by a standard soldered connection.

10. Current measuring device according to one of the preceding claims, characterized in that the circuit board (7) is equipped with at least one of the following components (23-26): a) an analog-to-digital converter (24), b) a component (26) for galvanically isolated data transmission, c) a microprocessor (25), wherein the microprocessor (25) is optionally arranged on the high side of the component (26) for galvanically isolated data transmission or on the low side of the component (26) for galvanically isolated data transmission, d) an interface (8).

11. Current measuring device according to one of the preceding claims, characterized in that, a) that the circuit board (7) is connected to the two terminal parts (2, 3) of the current-sensing resistor (1) at at least four connection points (30.1, 30.2, 31.1, 31.2), and / or b) that the four connection points (30.1, 30.2, 31.1, 31.2) form a rectangle, and / or c) that the connection points (30.1, 30.2, 31.1, 31.2) each form several measurement channels in pairs, the measurement channels each measuring the voltage between the two terminal parts (2, 3) of the current-sensing resistor (1).

12. Current measuring device according to claim 11, characterized in that a) the connection points (30.1, 30.2, 31.1, 31.2) of the two measuring channels are arranged crosswise, or b) the connection points (30.1, 30.2, 31.1, 31.2) of the two measuring channels are arranged parallel.

13. Current measuring device according to one of the preceding claims, characterized in that a) the circuit board (7) is connected at at least two of the connection points to the two connection parts (2, 3) of the current measuring resistor (1) in order to measure the voltage drop across the resistance element (4) of the current measuring resistor (1), b) the circuit board (7) is optionally connected at at least one of the connection points to the resistance element (4) in order to allow a center tap on the resistance element (4).

14. Current measuring device according to one of the preceding claims, characterized in that the circuit board (7) is connected at two of the connection points to the first connection part (2) and at one of the connection points to the second connection part (3), wherein the three connection points form a closed voltage mesh.

15. Current measuring device according to one of the preceding claims, characterized in that the circuit board (7) includes an interface (8) to transmit a) measured values ​​of the voltage drop between the connection parts (2, 3) and / or b) measured values ​​of a temperature sensor arranged on the circuit board (7) to an external evaluation unit via the interface (8), wherein the interface (8) is preferably an analog interface.

16. Current measuring device according to one of claims 1 to 14, characterized in that a) the circuit board (7) carries an evaluation unit (25) which calculates the electric current (I) flowing through the current-sensing resistor (1) from the measured values ​​of the voltage drop between the connection parts (2, 3), b) the evaluation unit (25) is optionally connected to a temperature sensor (23) and takes the temperature into account for temperature correction when calculating the current (I) flowing through the current-sensing resistor (1), c) the circuit board (7) optionally has a digital interface (8) which is connected to the evaluation unit (25) on the circuit board (7) in order to output the electric current (I) calculated by the evaluation unit (25).

17. Current measuring device according to one of the preceding claims, characterized in that a) the circuit board (7) is a rigid circuit board (7), in particular made of glass fiber composite material, or b) the circuit board (7) is a flexible circuit board (7), or c) the circuit board (7) is a rigid-flex circuit board (7) which is partly rigid and partly flexible.

18. Current measuring device according to one of the preceding claims, characterized in that a) the current measuring resistor (1) is low-resistance with an electrical resistance of at most 10 pQ, 25 pQ, 50 pQ, 100 pQ, 200 pQ or 500 pQ and / or b) the current measuring resistor (1) has a current rating of at least 100 A, 200 A, 500 A, 1 kA, 2 kA or 5 kA, and / or c) the current measuring resistor (1) is plate-shaped, in particular flat or curved, and / or d) the resistive element (4) is plate-shaped, in particular as a flat or curved plate, and / or e) the connecting parts (2, 3) are each plate-shaped, in particular as a flat or curved plate, f) the resistive element (4) of the current measuring resistor (1) has a smaller thickness than the connecting parts (2, 3). 3) of the current-sensing resistor (1), and / or g) that in the current-sensing resistor (1) the resistance element (4) is replaced by a welding- bond with the connecting parts (2, 3), in particular by electron beam welding, and / or h) that the current-sensing resistor (1) has an electrical resistance value with a temperature coefficient of not more than 200 ppm / K, 100 ppm / K, 50 ppm / K, 20 ppm / K or 10 ppm / K, and / or i) that the conductor material of the connecting parts (2, 3) of the current-sensing resistor (1) is copper, a copper alloy, aluminum or an aluminum alloy, and / or j) that the resistive material of the resistive element (4) of the current-sensing resistor (1) is one of the following alloys: jl) a copper alloy, in particular a copper-manganese alloy, in particular CuMn12Ni2 or CuMn7Sn2,3, or a copper-manganese-nickel alloy, in particular Cu84Ni4Mn12 or Cu65Mn25NiO, or a copper-chromium alloy, j2) a nickel alloy, in particular NiCr or CuNi, and / or k) that the conductor material of the connecting parts (2,3) the current-sensing resistor (1) has a lower specific electrical resistance than the resistive material of the resistive element (4) of the current-sensing resistor (1), and / or l) that the current-sensing resistor (1) has a length in the main current flow direction which is in the range of 5 mm–200 mm, and / or m) that the current-sensing resistor (1) has a width perpendicular to the main current flow direction which is in the range of 10 mm–100 mm, and / or n) that the current-sensing resistor (1) has a thickness perpendicular to the main current flow direction which is in the range of 1 mm–5 mm, and / or o) that the press connections each have an electrical contact resistance which is less than 1 p / mm, 2 .

19. Manufacturing method for a current measuring device, in particular for a current measuring device according to one of the preceding claims, comprising the following steps: a) providing a current measuring resistor (1) with two terminal parts (2, 3) made of a conductor material and a resistance element (4) made of a resistance material, wherein the resistance element (4) is arranged in the current flow direction between the two terminal parts (2, 3), b) providing a circuit board (7), and c) establishing an electrical connection between the circuit board (7) and the two terminal parts (2, 3) of the current measuring resistor (1) at at least two connection points (30, 31; 30.1, 30.2, 31.1, 31.2). characterized in that d) the connection between the circuit board (7) and the two connection parts (2, 3) of the current measuring resistor (1) at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2) is made by pressing, wherein the circuit board (7) and the connection parts (2, 3) are pressed together, in particular by means of a press die.

20. Manufacturing method according to claim 19, characterized in that a) when the circuit board (7) and the connection parts (2, 3) are pressed together at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2), heat is applied so that a press-sintered connection is formed between the circuit board (7) and the connection parts (2, 3), b) optionally, a sintered material, in particular silver or copper, is additionally added before pressing together at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2), c) the heat applied at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2) leads to heating to a sintering temperature, d) the sintering temperature is below the melting temperature of the conductor material and the resistance material, e) the f) that the sintering temperature is preferably greater than +100°C, +200°C or +250°C, f) that the sintering temperature is preferably at most +500°C, +400°C or +280°C.

21. Manufacturing method according to claim 19, characterized in that a) the connecting parts (2, 3) and / or the resistance element (4) are coated with an adhesive, in particular an epoxy adhesive, at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2) before being pressed together, so that a press-fit adhesive connection is formed at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2), b) that the pressing together preferably takes place without an additional heat input.

22. Manufacturing method according to one of claims 19 to 21, characterized by the following step before pressing together the circuit board (7) and the connection parts (2, 3) of the current measuring resistor (1): Creating a surface structure on the connection parts (2, 3) and / or on the resistive element (4) at the connection points (30, 31; 30.1, 30.2, 31.1, 31.2), in particular a nano-structure, wherein the surface structure optionally includes at least one of the following materials: a) ENIG, b) ENEPIG, c) Gold, d) Copper, e) Nickel-phosphorus, f) Silver.

23. Manufacturing method according to one of claims 19 to 22, characterized by the following steps: a) introducing recesses (12, 13) into the connecting parts (2, 3) of the current-sensing resistor (1), in particular for adjusting the temperature coefficient of the electrical resistance value of the current-sensing resistor (1), in particular by one of the following methods: a) embossing, a2) milling, a3) laser cutting, b) optionally measuring the temperature coefficient of the electrical resistance value of the current-sensing resistor (1) during the manufacturing process, and / or c) adjusting the temperature coefficient of the electrical resistance value of the current-sensing resistor (1) by adjusting the depth of the recesses (12, 13).

24. Manufacturing method according to one of claims 19 to 22, characterized in that a) contact fingers (9-11; 34-36) are formed in the circuit board (7) which protrude from the circuit board (7), in particular next to each other and in the same direction, b) that slots are optionally provided in the circuit board (7) to form the contact fingers (9-11; 34-36).

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