Device, in particular sensor device comprising a sensor unit, and method for producing such a device

Abstract

The invention relates to a device (10, 11), in particular a sensor device comprising a sensor unit (100), the device (10, 11) having a printed circuit board (20) and an electrical energy storage element (30), and a first metal welding plate (21, 23) and a second metal welding plate (22, 24) being arranged on the printed circuit board (20) and each being mechanically fixedly and electrically connected to the printed circuit board (20), and the energy storage element (30) having a first electrical connection (31) comprising a first metal connection lug (32) and having a second electrical connection (33) comprising a second metal connection lug (34), the first connection lug (32) and the second connection lug (34) being arranged and configured in such a way that the first connection lug (32) rests at least partially on the first welding plate (21, 23) and the second connection lug (34) rests at least partially on the second welding plate (22, 24) and each connection lug is cohesively connected, in particular welded, to the respective welding plate. The invention also relates to a method for producing a device (10, 11) according to the invention.

Description

[0001] R. 415998

[0002] - 1 -

[0003] Description

[0004] Device, in particular sensor device with a sensor unit, and method for manufacturing such a device

[0005] State of the art

[0006] Devices, especially sensor devices with a sensor unit, are often equipped with an electrical energy storage element for power supply. As a rule, the connecting tabs of the energy storage element, which lead to the circuit board, are made of stainless steel, whereby they are electroplated with nickel and tin depending on the connection technology to the circuit board.

[0007] One such sensor device could be a tire pressure sensor. A tire pressure sensor is an important component of modern vehicles, used to measure and monitor tire pressure. Proper tire pressure significantly contributes to improving vehicle safety, efficiency, and driving comfort, while simultaneously extending tire lifespan. Tire pressure sensors are used not only in cars and trucks, but also in bicycles and bicycle trailers, for example. Data transmission from the tire pressure sensor to an external receiver or device is typically wireless.

[0008] In the current state of the art, there are various ways to connect the electrical energy storage device to the circuit board of the device. Typically, this involves either soldering, press-fitting, or welding, where the energy storage element is welded directly onto the circuit board. However, all these methods present certain problems.

[0009] Welding directly onto a printed circuit board pad introduces a significant amount of energy into the board, as the welding process requires reaching certain temperatures. These temperatures are therefore locally much higher than the maximum permissible temperatures for the layers of the printed circuit board (R. 415998).

[0010] - 2 - between the copper layers. This can lead to delamination between the layers and the circuit board pad, which can cause the device to have a technical defect immediately or over time.

[0011] Soldering requires selectively applying solder and applying heat to each pole of the energy storage element separately. To ensure solder quality, appropriate monitoring procedures must be used during manufacturing. This process is therefore slow, expensive, and requires additional manufacturing space for testing equipment. Furthermore, the terminals of the energy storage element must be tinned. Press-fitting requires the energy storage elements to have designated press-fit zones, with very high positional accuracy requirements for the pin tips. The reduced positional accuracy can potentially be compensated for by design features in the housing (e.g., recesses into which the press-fit zone is pressed). However, this leads to increased stress on the weld joint of the energy storage element.

[0012] The aforementioned problems in the prior art are to be solved, or at least reduced or optimized, by means of the invention.

[0013] Disclosure of the invention

[0014] The invention relates to a device, in particular a sensor device with a sensor unit, wherein the device comprises a printed circuit board and an electrical energy storage element, and wherein a first metallic welding plate and a second metallic welding plate are arranged on the printed circuit board, each of which is mechanically fixed and electrically connected to the printed circuit board, and wherein the energy storage element has a first electrical connection with a first metallic connecting tab and a second electrical connection with a second metallic connecting tab, wherein the first connecting tab and the second connecting tab are arranged and configured such that the first connecting tab is at least partially located on the first welding plate and the second connecting tab is located on the second metal connecting tab.

[0015] - 3 - at least partially rests on the second welding plate and is welded to it in each case.

[0016] The advantage here is that, compared to a prior art device, delamination of the printed circuit board (PCB) due to excessive temperatures typically does not occur. This is because the welding plate distributes the heat during the metallurgical bonding of the connecting tab to the welding plate in such a way that the maximum permissible temperatures for the PCB itself are not exceeded. Furthermore, the manufacturing costs of the device are low due to the good process control and the short cycle time of the welding process, while still enabling a robust connection between the energy storage element and the PCB.

[0017] The device can, in particular, be a sensor device with a corresponding sensor unit. For example, the sensor device can be designed as a tire pressure sensor and include a corresponding pressure sensor element for detecting tire pressure. Tire pressure is understood to be the pressure in a tire filled with a medium, especially air. A tire can be from any means of transport with correspondingly medium-filled wheels, such as a car, truck, bicycle, or even an aircraft. In addition to the actual pressure sensor element, the sensor unit typically includes, among other things, a processing unit, such as an ASIC or a microcontroller, which can process data, for example, measurement data from the pressure sensor element, and control other electrical components as needed.The pressure sensor element can be designed, for example, as a piezoelectric or capacitive sensor, which can convert the vibrations of a membrane into an electrical signal. Alternatively, a sensor with a different sensor principle is also conceivable. The pressure sensor element is designed and arranged in such a way that tire pressure can be detected using the pressure sensor element.

[0018] In particular, the pressure sensor element can be designed as a MEMS component. Alternatively or additionally, the sensor unit can include an accelerometer element or other sensor elements. R. 415998

[0019] - 4 -

[0020] A printed circuit board (PCB), also known as a printed circuit board, is a flat board made of insulating material on which conductive paths and connections for electronic components are mounted. The PCB serves as mechanical support and electrical connection for electronic components such as resistors, capacitors, transistors, integrated circuits, and other electronic parts. All electronic components, such as the sensor unit and other necessary components like crystals, voltage regulators, and capacitors, can be mounted on the PCB.

[0021] An electrical energy storage element is a component that stores electrical energy and releases it when needed. The released energy can then be used, for example, to power a sensor unit. Examples of electrical energy storage elements include batteries, capacitors, and superconducting magnetic field storage devices. A lithium-ion battery, such as a button cell, can be used as a battery. However, any other battery is also suitable, provided it is small enough and provides the necessary supply voltage. Both secondary and primary cells can be used as energy storage elements. The energy storage element has corresponding electrical connections with terminals. Terminals are small, flat metal parts.They are typically used to create electrical connections by being soldered or screwed onto cables or circuit boards. They are often used in electronic devices, circuits, and other electrical applications to establish a reliable electrical connection.

[0022] A weld plate is essentially a flat, planar element. It is, in particular, a small piece of metal that serves as a counterpart for the connecting tab of the energy storage element during the welding process. Through welding, the weld plate is at least partially fused to the connecting tab, creating an electrical and mechanical connection. R. 415998

[0023] - 5 -

[0024] Welding is used to create a material-bonded connection between the welding plates and the connecting tabs. This allows for a mechanical and electrical connection between the circuit board and the energy storage element.

[0025] One embodiment of the invention provides that the first welding plate and the second welding plate are at least partially bonded to the circuit board, in particular by soldering and / or by gluing.

[0026] The advantage here is that this is a simple way to mechanically and electrically connect the weld pad to the circuit board. The resulting bond is extremely durable and ensures a long-lasting and therefore reliable device.

[0027] A material-bonded connection refers to a bond in which two materials are connected by molecular or atomic forces. This type of connection is based on the attractive force between the molecules or atoms of the materials involved. Examples of material-bonded connections include welding, gluing, and soldering. Gluing can be achieved, in particular, using an electrically conductive adhesive. The quality of a solder joint can be advantageously controlled using the standard equipment of the production line.

[0028] One embodiment of the invention provides that the respective connecting tab is arranged to rest on the respective welding plate in such a way that the respective connecting tab only partially, in particular halfway, overlaps the respective welding tab.

[0029] The advantage here is that the material-bonded connection between connecting tabs and welding plates can be created particularly easily using a resistance welding process, since the components to be welded (connecting tabs and welding plates) can be contacted directly, especially from above, during production.

[0030] Such a manufacturing process offers a high degree of process control through the simple measurement of process parameters such as current, voltage, resistance, or R. 415998

[0031] - 6 - also melting path. In addition, weld spatter can be detected based on the process parameters. Thus, such a device can be manufactured cost-effectively and reliably.

[0032] The design ensures that a portion of each welding plate, particularly its upper surface, remains free of the connecting tab. This facilitates easy contact between the welding plate and the welding electrode during the manufacturing process. Simultaneously, contacting the connecting tab with another welding electrode is also straightforward. The welding electrode for the connecting tab is hemispherical, especially in the contact area. This hemispherical shape creates a point-like connection with a minimal cross-section. The welding current must pass through this narrow point, heating the components locally and resulting in resistance welding.

[0033] A further embodiment of the invention provides that the respective connecting tab is arranged to rest on the respective welding plate in such a way that the respective connecting tab essentially completely overlaps the respective welding tab.

[0034] The advantage here is that the material-bonded connection between the connecting tab and the welding plate can be optimally created using a laser beam welding process, since direct contact of the welding plate is difficult or impossible to achieve with this design. However, with laser beam welding, it is sufficient that one of the components to be welded is contactable or visible. This method exhibits a very low tendency to produce weld spatter. Therefore, such a device can be manufactured simply, quickly, and reliably.

[0035] In particular, the overlap ensures that the upper surface of the welding plate is covered by the connecting tab. R. 415998

[0036] - 7 -

[0037] According to a further embodiment of the invention, it is provided that the first welding plate and the second welding plate each have a protrusion, wherein the respective protrusion has a contact area with the respective connecting tab, in particular a point-like contact area, and is in particular hemispherical in shape.

[0038] The advantage here is that the metallurgical bond between the connecting tabs and the welding plates can be created particularly easily using a resistance welding process. The raised area creates a contact between the welding plate and the connecting tabs with a small cross-section, allowing for easy welding in this small cross-sectional area. This manufacturing method offers a high degree of process control through the simple measurement of process parameters such as current, voltage, resistance, and melting distance. Therefore, such a device can be manufactured cost-effectively and reliably.

[0039] A raised area is a feature that stands out from the main surface of the welding plate. This raised area can be created, for example, by an appropriate embossing process on the welding plate. However, it is also conceivable that the raised area is applied to the welding plate as additional material. In this case, the raised area allows the welding electrode, which contacts the connecting tab, to be made flat and placed on the connecting tab in the area above the raised area. The raised area itself creates a point-like connection between the connecting tab and the welding plate with a minimal cross-section. The welding current must pass through this narrow point and heats the components locally, which in turn leads to resistance welding. Alternatively or additionally, laser beam welding in the contact area between the connecting tab and the welding plate is also possible.

[0040] Alternatively or additionally, the connecting tab could also have a raised section that points towards the welding plate. R. 415998

[0041] - 8 -

[0042] The invention further relates to a method for manufacturing a device according to the invention, comprising the following method steps: a. providing a printed circuit board, b. attaching a first metallic welding plate and a second metallic welding plate to the printed circuit board such that the first welding plate and the second welding plate are mechanically and electrically connected to the printed circuit board, c. providing an electrical energy storage element with a first electrical connection having a first metallic connecting tab and a second electrical connection having a second metallic connecting tab, d. arranging the first connecting tab and the second connecting tab such that the first connecting tab rests at least partially on the first welding plate and the second connecting tab rests at least partially on the second welding plate, and e.Welding the first connecting tab to the first welding plate and the second connecting tab to the second welding plate.

[0043] A key advantage here is that, compared to a prior art device, delamination of the printed circuit board (PCB) due to excessive temperatures typically does not occur during manufacturing. This is because the welding plate distributes the heat during the metallurgical bonding of the connecting tab to the welding plate in such a way that the maximum permissible temperatures for the PCB itself are not exceeded. Furthermore, the manufacturing costs of the device are low due to the good process control and the short cycle time of the welding process, while still enabling a robust connection between the energy storage element and the PCB.

[0044] In particular, process step c can run parallel to process steps a and b, or between or before them. R. 415998

[0045] - 9 -

[0046] According to a further embodiment of the invention, it is provided that in process step d the respective connecting tab partially overlaps the respective welding plate, wherein in process step e a first welding electrode is placed on the respective welding plate and a second welding electrode is placed in the overlapping area on the respective connecting tab, and subsequently, by means of an electric current flow between the first welding electrode and the second welding electrode, resistance welding of the respective welding plate with the respective connecting tab takes place.

[0047] The advantage here is that the material-bonded connection between connecting tabs and welding plates can be created particularly easily using a resistance welding process, since the components to be welded (connecting tabs and welding plates) can be contacted directly, especially from above, during production.

[0048] This manufacturing process offers a high degree of process control through the simple measurement of process parameters such as current, voltage, resistance, and melting path. Furthermore, weld spatter can be detected based on these process parameters. Therefore, such a device can be manufactured cost-effectively and reliably.

[0049] According to one embodiment of the invention, it is provided that in process step e the second welding electrode is placed at a point on the respective connecting tab, and in particular is designed to be hemispherical in the contact area.

[0050] The advantage here is that the point-contact connection of the second welding electrode in the contact area with the terminal tab results in a minimal cross-section. This allows, during resistance welding, this contact area and the adjacent terminal tab to be heated locally by the corresponding current flow between the first and second welding electrodes, since the current must flow through this narrow point in the contact area, and thus welded to the adjacent weld pad. R. 415998

[0051] - 10 -

[0052] According to one embodiment of the invention, it is provided that the first welding plate and the second welding plate each have a protrusion, which in particular was produced by means of an embossing process, wherein in process step e the second welding electrode lies flat against the respective connecting tab.

[0053] The advantage here is that the metallurgical bond between the connecting tabs and the welding plates can be created particularly easily using a resistance welding process. The raised area creates a contact between the welding plate and the connecting tabs with a small cross-section, allowing for easy welding in this small cross-sectional area. This manufacturing method offers a high degree of process control through the simple measurement of process parameters such as current, voltage, resistance, and melting distance. Therefore, such a device can be manufactured cost-effectively and reliably.

[0054] According to one embodiment of the invention, it is provided that in process step d the respective connecting tab at least partially overlaps the respective welding plate, in particular substantially completely overlaps, wherein in process step e the respective connecting tab is pressed onto the respective welding plate by a hold-down element and is at least partially joined to the respective welding plate in the overlap area by means of a laser beam welding process.

[0055] The advantage here is that the material-bonded connection between the connecting tab and the welding plate can be optimally produced using a laser beam welding process, since direct contact of the welding plate is difficult or impossible to achieve with a corresponding device design. With laser beam welding, however, it is sufficient that one of the components to be welded is contactable or visible. This method exhibits very little tendency to produce weld spatter. Therefore, such a device can be manufactured simply, quickly, and reliably. R. 415998

[0056] - 11 -

[0057] Drawings

[0058] Fig. 1 shows a first embodiment of a device according to the invention in a perspective view and a side sectional view.

[0059] Fig. 2 shows the first embodiment of a device according to the invention in a side sectional view.

[0060] Fig. 3 shows a second embodiment of a device according to the invention in a side sectional view.

[0061] Fig. 4 shows a section of the second embodiment of a device according to the invention in a perspective view.

[0062] Fig. 5 shows an embodiment of a method according to the invention for manufacturing a device according to the invention.

[0063] Description of exemplary implementations

[0064] Fig. 1 shows a first embodiment of a device according to the invention in a perspective view in a side sectional view.

[0065] The figure shows a device 10. The device 10 has a circuit board 20 and an electrical energy storage element 30.

[0066] Furthermore, device 10 has a sensor unit 100, which is arranged on a subside of the circuit board 20 and includes, for example, a pressure sensor element for detecting tire pressure, a control unit, a radio module, or other electronic components. The sensor unit 100 can, for example, also include an accelerometer element.

[0067] On the upper side of the circuit board 20, a first metallic welding plate 21 and a second metallic welding plate 22 are arranged, each mechanically fixed and electrically connected to the circuit board 20 R. 415998

[0068] - 12 - are connected. The first welding plate 21 and the second welding plate 22 can be at least partially bonded to the circuit board 20. In particular, this bonded connection can be made by soldering and / or by gluing.

[0069] The energy storage element 30 has a first electrical connection 31 (not shown here) with a first metallic connecting tab 32 and a second electrical connection 33 with a second metallic connecting tab 34, wherein the first connecting tab 32 and the second connecting tab 34 are arranged and configured such that the first connecting tab 32 rests at least partially on the first welding plate 21 and the second connecting tab 34 rests at least partially on the second welding plate 22 and is metallurgically bonded to each. This metallurgical bond is configured as a weld. The respective connecting tab 32, 34 is arranged resting on the respective welding plate 21, 22 such that the respective connecting tab 32, 34 only partially, in particular halfway, overlaps the respective welding tab 21, 22.

[0070] The energy storage element 30 is thereby electrically connected to the circuit board 20 and can, for example, supply the sensor unit 100 with electrical energy.

[0071] In an alternative embodiment, not shown in the illustration, the respective connecting tab 32, 34 can be arranged to rest on the respective welding plate 21, 22, 23, 24 in such a way that the respective connecting tab 32, 34 substantially completely overlaps the respective welding tab 21, 22, 23, 24.

[0072] In an alternative embodiment, not shown in the illustration, the sensor unit 100 could also be arranged partially or completely on the top side of the circuit board 20, whereby mounting the circuit board 20 entirely on one side enables cost-effective manufacturing of the device. R. 415998

[0073] - 13 -

[0074] Fig. 2 shows the first embodiment of a device according to the invention in a side sectional view.

[0075] The device 10, shown again in section along the plane A of Fig. 1, is depicted. The assembly, consisting of the circuit board 20, the energy storage element 30, and the corresponding mechanical and electrical connections via the weld plates 21, 22 and the connecting tabs 32, 34, is revealed once more. The first connection 31 of the electrical energy storage element 31 is also clearly visible. The connecting tabs 32, 34 are, for example, also metallurgically bonded to the electrical connections 31, 33.

[0076] Fig. 3 shows a second embodiment of a device according to the invention in a side sectional view.

[0077] A device 11 is shown in a sectional view, which differs from the device 10 from Fig. 1 and Fig. 2 in that in the device 11 the first welding plate 23 has a protrusion 25 and, not visible here, the second welding plate 24 has a protrusion 26, wherein the respective protrusion 25, 26 has a contact area with the respective connecting tab 32, 34, and is in particular hemispherical in shape.

[0078] In an alternative embodiment, not shown in the illustration, the respective connecting tab 32, 34 could additionally or alternatively have a corresponding projection in addition to the respective projection 25, 26, which is formed towards the respective welding plate 21, 22, 23, 24.

[0079] Fig. 4 shows a section of the second embodiment of a device according to the invention in a perspective view.

[0080] The figure shows a section of the device 11 from Fig. 3 in a perspective view. In particular, the circuit board 20 and the R. 415998 are shown.

[0081] - 14 - The first welding plate 23 and the second welding plate 24 can be seen. In addition, the hemispherical shape of the elevations 25, 26 is clearly recognizable.

[0082] Fig. 5 shows an embodiment of a method according to the invention for manufacturing a device according to the invention.

[0083] A method for manufacturing a device according to the invention 10, 11 is shown.

[0084] In process step a, a printed circuit board 20 is provided. Then, in process step b, a first metallic welding plate 21, 23 and a second metallic welding plate 22, 24 are attached to the printed circuit board 20 such that the first welding plate 21, 23 and the second welding plate 22, 24 are mechanically and electrically connected to the printed circuit board 20. This can be done, for example, by soldering or by gluing.

[0085] Furthermore, in a process step c, which can run parallel to process steps a and b or also between or before them, an electrical energy storage element 30 is provided with a first electrical connection 31 with a first metallic connecting tab 32 and a second electrical connection 33 with a second metallic connecting tab 34.

[0086] Subsequently, in a process step d, the first connecting tab 32 and the second connecting tab 34 are arranged such that the first connecting tab 32 rests at least partially on the first welding plate 21, 23 and the second connecting tab 34 rests at least partially on the second welding plate 22, 24.

[0087] Subsequently, in a process step f, the first connecting tab 32 is joined to the first welding plate 21, 23 and the second connecting tab 34 is joined to the second welding plate 22, 24 by means of a metallurgical bond. This joining is carried out by welding.

[0088] In particular, in process step d the respective connecting tab 32 34 can be arranged such that it connects to the respective welding plate 21 , R. 415998

[0089] - 15 -

[0090] 22, 23, 24 partially overlap. Furthermore, in process step e, a first welding electrode can be placed on the respective welding plate 21, 22, 23, 24, and a second welding electrode can be placed in the overlapping area on the respective connecting tab 32, 34. Subsequently, resistance welding of the respective welding plate 21, 22, 23, 24 to the respective connecting tab 32, 34 is carried out by means of an electric current flowing between the first and second welding electrodes. The second welding electrode can be applied, in particular, at a specific point on the respective connecting tab 32, 34, and the second welding electrode can, in particular, be hemispherical in the contact area.

[0091] Alternatively or additionally, the first welding plate 23 and the second welding plate 24 can each have a protrusion 25, 26, which were produced in particular before process step b by means of an embossing process, wherein in process step e the second welding electrode lies flat against the respective connecting tab 32, 34.

[0092] In an alternative embodiment, the respective connecting tab 32, 34 can be arranged to overlap the respective welding plate 21, 22, 23, 24 at least partially, and in particular to overlap substantially completely, wherein in process step e the respective connecting tab 32, 34 is transferred from a hold-down element to the respective welding plate 21, 22,

[0093] 23, 24 are pressed and, at least partially in the overlap area, are joined to the respective welding plate 21, 22, 23, 24 by means of a laser beam welding process.

Claims

R. 415998 - 16 - Claims 1. Device (10, 11), in particular a sensor device with a sensor unit (100), wherein the device (10, 11) comprises a printed circuit board (20) and an electrical energy storage element (30), and wherein a first metallic weld plate (21, 23) and a second metallic weld plate (22, 24) are arranged on the printed circuit board (20), each of which is mechanically fixed and electrically connected to the printed circuit board (20), and wherein the energy storage element (30) has a first electrical connection (31) with a first metallic connection tab (32) and a second electrical connection (33) with a second metallic connection tab (34), wherein the first connection tab (32) and the second connection tab (34) are arranged and designed such that the first connection tab (32) is at least partially attached to the first weld plate (21, 23).23) and the second connecting tab (34) rests at least partially on the second welding plate (22, 24) and is welded to it in each case.

2. Device (10, 11) according to claim 1 , characterized in that the first welding plate (21 , 23) and the second welding plate (22, 24) are at least partially bonded to the circuit board (20), in particular by soldering and / or by gluing.

3. Device (10, 11) according to one of the preceding claims, characterized in that the respective connecting tab (32, 34) is arranged to rest on the respective welding plate (21 , 22, 23, 24) in such a way that the respective connecting tab (32, 34) only partially, in particular halfway, overlaps the respective welding tab (21 , 22, 23, 24).

4. Device (10, 11) according to claim 1 or 2, characterized in that the respective connecting tab (32, 34) is arranged to rest on the respective welding plate (21 , 22, 23, 24) in such a way that the respective connecting tab (32, 34) substantially completely overlaps the respective welding tab (21 , 22, 23, 24). R. 415998 - 17 - 5. Device (11) according to one of the preceding claims, characterized in that the first welding plate (23) and the second welding plate (24) each have a projection (25, 26), wherein the respective projection (25, 26) has a contact area with the respective connecting tab (32, 34), in particular a point contact area, and is in particular hemispherical in shape.

6. Method for manufacturing a device (10, 11) according to one of the preceding claims, comprising the following method steps: a. Providing a printed circuit board (20), b. Attaching a first metallic welding plate (21, 23) and a second metallic welding plate (22, 24) to the printed circuit board (20) such that the first welding plate (21, 23) and the second welding plate (22, 24) are mechanically and electrically connected to the printed circuit board (20), c. Providing an electrical energy storage element (30) with a first electrical connection (31) with a first metallic connecting tab (32) and a second electrical connection (33) with a second metallic connecting tab (34), d.Arranging the first connecting tab (32) and the second connecting tab (34) such that the first connecting tab (32) rests at least partially on the first welding plate (21, 23) and the second connecting tab (34) rests at least partially on the second welding plate (22, 24), and welding the first connecting tab (32) to the first welding plate (21, 23) and the second connecting tab (34) to the second welding plate (22, 24).

7. Method according to claim 6, characterized in that in process step d the respective connecting tab (32, 34) partially overlaps the respective welding plate (21, 22, 23, 24), wherein in process step e a first welding electrode is placed on the respective welding plate (21, 22, 23, 24) and a second welding electrode is placed in the overlapping area on the respective R. 415998 - 18 - Connecting flags (32, 34) are attached, and then resistance welding of the respective welding plate (21, 22, 23, 24) with the respective connecting flag (32, 34) is carried out by means of an electric current flow between the first welding electrode and the second welding electrode.

8. Method according to claim 7, characterized in that in process step e the second welding electrode is in contact with the respective connecting tab (32, 34) at a specific point, and is in particular designed to be hemispherical in the contact area.

9. Method according to one of claims 6 to 8, characterized in that the first welding plate (23) and the second welding plate (24) each have a protrusion (25, 26) which in particular was produced by means of an embossing process, wherein in process step e the second welding electrode lies flat against the respective connecting tab (32, 34).

10. Method according to claim 6, characterized in that in process step d the respective connecting tab (32, 34) at least partially overlaps the respective welding plate (21, 22, 23, 24), in particular substantially completely overlaps, wherein in process step e the respective connecting tab (32, 34) is pressed onto the respective welding plate (21, 22, 23, 24) by a hold-down element and at least partially welded to the respective welding plate (21, 22, 23, 24) in the overlap area by means of a laser beam welding process.

Images