Method for manufacturing an electrotechnical mechanism, electronic control device and electrotechnical mechanism

Abstract

An electronic control device, an electrotechnical arrangement, and a method for manufacturing an electrotechnical arrangement are proposed. The electrotechnical arrangement (10) comprises a circuit board (3), an electric component (2), and an insulating element (4), the circuit board (3) being injection-enclosed with the insulating element (4), the insulating element (4) having a side (5) aligned at an angle with respect to a direction Z defined perpendicular to the surface of the circuit board (3), and the component (2) being fixed on the circuit board (3) at the base of the side (5) of the insulating element (4).

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an electro-technical mechanism, an electronic control device and an electro-technical mechanism.The present invention relates in particular to a simple, inexpensive and precise positioning of an electrical component on a circuit board for bonding. [Background technology]

[0002] Modern power boards are based on ceramic structures with metallic top and bottom surfaces. On this the power switches (IGBT, MOSFET, ...) are mounted and wired. Due to the substrate, branching is only possible in two spatial dimensions. Bonding is available as external contact (ribbons, wires). Stamped parts are also used, which are contacted by ultrasonic or laser welding. These connection elements are already part of one of the joining partners. Summary of the Invention [Problem to be solved by the invention]

[0003] In this case, there is a demand for a method for positioning / centering the connecting elements ("on-board electrical elements") that are to be subsequently bonded to the power substrate. This positioning must be reliable, reliable and precise. This is a prerequisite for a low inductance structure, as would be advantageous for switch modules with SiC-MOSFETs. [Means for solving the problem]

[0004] The above requirements are met by an electro-technical arrangement having the features of the independent claim 1. The dependent claims indicate preferred variants of the invention. The design element provided here is based on the idea that the connection between the substrate-based module and the intermediate circuit capacitor is not established in one manufacturing step, but is instead separated into separate manufacturing steps, resulting in a construction scheme that satisfactorily solves the problems listed above. The design element also allows the relevant requirements for clearance and creepage distances to be changed or adjusted. The design element envisaged here results in a position centering of the joining partners in the X-direction and the Y-direction. With the joining process, the joining parts are guided in the Z-direction during the process to their final position. In this respect, the centering principle (Z-direction) is flexible. The draft angle on the electronics part serves in this case as a funnel-shaped catch. With the funnel-shaped catch, the creepage distances for electrical short circuits can also be adjusted.

[0005] In other words, an electrotechnical arrangement is proposed which has a circuit board (substrate) and at least one electrical component. The electrical component may, for example, include power switches (IGBT, MOSFET, etc.). In addition to this, an insulating element is provided, which is provided in particular on the edge side of the circuit board. The insulating element may be provided in particular as an electrical insulator between the upper and lower sides of the circuit board. In this way, the circuit board is injection-surrounded with the insulating element. In this way, the circuit board can be understood or produced as a frame that goes at least approximately around the periphery of the circuit board or as an edge of the circuit board. The insulating element has a side that is aligned at an angle to a direction Z defined perpendicular to the surface of the circuit board. This side may also be understood as a ramp, a bevel, or a slope. The component is fixed on the circuit board at the base of this side of the insulating element. In particular, there is an electrical connection between the component and the circuit board in the region of the base of this side. However, the component at least has a section or structure that is arranged on the circuit board or on a conductor path that is on the circuit board before and after the component is joined. In this way, the component is fixed by the section at the base of the side surface in a target position on the circuit board, while the component may have a much larger position error relative to the circuit board during the approach to the circuit board (in the upper region of the side surface). This side surface provides a so-to-speak forced reduction of the position error during the approach of the component to the circuit board. This side surface of the insulating element can therefore also be understood as a component of a funnel or a positioning ramp. If the component engages with this side surface of the insulating element in a predefined manner, the component can only reach the target position during the approach to the circuit board. In particular, the section of the component guided by this side surface can be clamped between this side surface and a further structure (e.g. an edge / inner further side surface of the insulating element), so that the horizontal error relative to the surface of the circuit board is very small before the component is glued, welded, soldered, etc. onto the circuit board. For this purpose, the component can be pressed onto the circuit board, during which process sections of the component in the region of the root of the sides are clamped and optionally even forcibly deformed / preloaded.In particular, this part of the component can be braked by friction on the side, while the remaining components of the component continue to move towards the circuit board until they finally come into contact with the circuit board and are electrically coupled to it. The electrical coupling can be effected, in particular, by pads or conductor tracks arranged on the circuit board. In this way, insulating elements provided on the circuit board for electrical insulation can also be used to facilitate the positioning of the electrical component on the circuit board.

[0006] The component may in particular comprise a stamped part, preferably having a conductor track for electrically contacting a predefined area on the circuit board. In particular, the area of ​​the component to be arranged in the region of the root of the side surface may be made elastic (in particular spring-elastic) in order to ensure a precise positioning of the part with respect to the circuit board before the electrical component is (electrically and / or mechanically) connected to the circuit board. In other words, during the production of the electrotechnical system, the electrical component slides down this side surface of the insulating element at least to a corresponding extent until the electrical component is placed in its target position on the circuit board by this side surface. This side surface may have, for example, a linear shape in order to keep constant the frictional forces during the approach of the electrical component to the circuit board along the path Z.

[0007] The length of this side can be at least 30%, preferably 80% or more, of the thickness of the insulating element in the Z-direction above the surface of the circuit board. In other words, this side spans at least 30%, preferably 80%, in particular 90% or more, of the height of the insulating element in the Z-direction. In this way, relatively large initial positioning errors of the electrical component relative to the circuit board can be eliminated solely on the basis of this side of the insulating element during the approach of the electrical component to the circuit board.

[0008] The total thickness of the insulating element above the surface of the circuit board in the region of this side can be at least 10 mm, preferably 20 mm, very preferably 30 mm, or in a range between the aforementioned values, where the total thickness of the insulating element above the surface of the circuit board in the region of this side is determined based on the selected side angle in interaction with the manufacturing and component tolerances to be removed, and is in this case usually between 3 mm and 30 mm, in particular an integer multiple of 1 mm within the aforementioned range.

[0009] The insulating element may be provided as an electrical insulator in the mechanism. The insulating element may be provided to avoid surface leakage currents between the upper and lower surfaces of the circuit board. For this purpose, the insulating element surrounds the edge / cut edge of the circuit board at least in the area of ​​the surface where a voltage worth mentioning in case of operation can be expected. The insulating element may be provided with flanks according to the invention at different edges of the circuit board in order to frame the circuit board as it were and thus to displace the electric component in the X / Y direction horizontal to the circuit board when the electric component is approached to the circuit board. The flanks may be formed as draft angles. In other words, the flanks may also be provided to facilitate the release of the insulating element from the injection mold in which the insulating element was injection molded on the circuit board. Alternatively or additionally, the flanks may be components of a funnel-shaped catch or a V-shaped notch. In this connection, the funnel-shaped part should not necessarily be considered as a conical hollow shape in some sections, but may for example include two substantially flat flanks causing respective displacements of the electric component in different directions horizontal to the surface of the circuit board in order to guide the electric component to its target position. The side surface may have an angle of between 5° and 50°, preferably between 10° and 45°, particularly preferably between 12° and 40°, with respect to the Z direction. Within this range, friction forces can be adapted even in the case of an inaccurate initial positioning of the electrical component on the circuit board, while a sufficient reduction of the initial positioning errors can be achieved in the course of the joining process.

[0010] The electro-technical mechanism according to the invention may have an additional side which together with this side in the insulating element forms a funnel. The alignment of the additional side may be rotated relative to the side, for example in an azimuth direction at the surface of the circuit board. In particular, an alignment of the side rotated substantially 90° about the Z direction may be such that both sides cooperate to provide for the positioning of the electrical component in both the X and Y directions.

[0011] Between the additional side and the side, a bottom structure in the insulating element may be provided, which covers the surface of the circuit board. In other words, the bottom of the funnel-shaped catch or V-shaped notch is filled / covered by the insulating material of the insulating element. The structure of the electrical component, which slides down the side / additional side, is therefore not in electrical / mechanical contact with the circuit board at the end of the joining process anyway, but rests on the bottom structure. This causes a preloading of the electrical component in its final position on the circuit board. Alternatively or in addition, one structure of the electrical component can be sandwiched between the additional side and the side, as this has already been detailed above. In this way, a positioning aid similar to a zero tolerance is provided for the electrical component. This positioning aid results in a precise positioning in the X- and / or Y-direction even before the electrical component contacts the circuit board in its final position.

[0012] According to a second aspect of the invention, a method for manufacturing an electro-technical arrangement as described in detail above in connection with the first inventive aspect is proposed. According to this method, the circuit board is first injection-surrounded with the insulating element. For this, in particular the edge area of ​​the circuit board can be initially enveloped with a liquid or pasty substance, which is then foamed and / or hardened in an injection mold. The formed insulating element can then have a height of in particular 1 / 20, preferably 1 / 10, very preferably 1 / 5 of the maximum longitudinal extent of the dimension of the circuit board. The electrical component is then placed on the circuit board, during which, in the course of a movement normal to the surface of the circuit board (Z direction), the component is aligned relative to the circuit board in the direction X and / or Y oriented perpendicular to the direction Z by the side surface of the insulating element that is placed on the circuit board and that is formed at an angle to the direction Z. The electrical component then slides at least to a corresponding extent along the side surface, so that it reaches a final position (target position) on the circuit board that is predefined by this side surface. In this connection too, the circuit board is to be understood as the part which determines the mechanical final position of the electrical components, without however requiring that this circuit board must not have further components or conductor tracks on which the electrical components are (proportionately) mounted. The features, feature combinations and advantages resulting therefrom of the method for producing an electro-technical arrangement according to the invention correspond so obviously to the features, feature combinations and advantages resulting therefrom detailed above in connection with the first-mentioned inventive aspect that reference is made to said detailed description in order to avoid repetition.

[0013] In a subsequent step, the electrical component can be mechanically and electrically (particularly galvanically) connected to the circuit board and / or to the conductor tracks on the circuit board. The connection can be made, for example, by friction welding and / or sintering and / or soldering and / or welding and / or riveting and / or gluing. In this way, the electrical component is guided to the target position on the circuit board, defined by the side surface in the insulating element, and is then connected to the circuit board for the defined functioning of the electrical component.

[0014] According to a third aspect of the invention, an electronic control device is proposed, which may be provided and adapted for use, for example, in an on-board network of a motor vehicle. The electronic control device comprises an electrotechnical arrangement according to the first-mentioned inventive aspect and is in particular manufactured according to a method according to the second-mentioned inventive aspect. The electronic control device may be formed, for example, as a control device of a motor and / or a transmission and / or a gateway. Alternatively or additionally, the electronic control device may be adapted in particular for steering a means of transport. More preferably, the electronic control device may be provided for an output conversion between a first voltage level and a second voltage level in the on-board network of a means of transport. Alternatively or additionally, the electronic control device may be formed for an output conversion from three-phase electrical energy to single-phase electrical energy or vice versa.

[0015] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 shows a schematic top view of the contact points of one exemplary embodiment of an electro-technical contact arrangement. [Diagram 2] 2 is a schematic diagram of overlapping contacts of electrical components in one exemplary embodiment of an electro-technical contact arrangement; FIG. [Diagram 3] FIG. 2 shows a side view of two electrical components as joining partners in one exemplary embodiment of an electro-technical contact arrangement; [Figure 4] FIG. 1 is a perspective view of one exemplary embodiment of an electro-technical arrangement according to the invention; [Diagram 5] 3 is a perspective view of a further exemplary embodiment of an electro-technical arrangement according to the invention; FIG. [Figure 6] 4 shows a side view of a further exemplary embodiment of an electro-technical arrangement according to the invention; FIG. [Figure 7] 4 shows a side view of a further exemplary embodiment of an electro-technical arrangement according to the invention; FIG. [Figure 8] 7 is a cross-sectional view of a partial area of ​​the electro-technical arrangement shown in FIG. 6; [Figure 9] FIG. 2 is a flow diagram illustrating the steps of one exemplary embodiment of the method for manufacturing an electro-technical mechanism according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 shows a top view of a substrate 3 on which contact points 1', 2' for contacting electrical components 1, 2 are arranged. The electrical component 1 has an electrical supply which passes electrically insulated between two contact points 1', 2' for the electrical component 2. The contact points 1', 2' have a substantially rectangular shape, however their corners are rounded. Between the contact points 1', 2' an insulating groove is provided, which has a width which is approximately 1 / 5 to 1 / 7 of the shortest extension of the contact points 1', 2' for the electrical components 1, 2.

[0018] Figure 2 shows a top view of the arrangement shown in Figure 1 after contacting of the contact points 1', 2' by the electrical components 1, 2. Precise positioning of the electrical components 1, 2 on the contact points 1', 2' is necessary, among other things, in order to avoid accidentally straddling the insulating groove between the contact points 1, 2'.

[0019] Figure 3 shows a side view of the contact arrangement 9 (see Figures 1, 2), in which the spatial relationship of the electrical components 1, 2 above the circuit board 3 can be seen. The electrical components 1, 2 are electrically and mechanically connected in a material-bonded manner, for example by friction welding, on their respective contact points 1', 2' (not shown here). From the contact points 1', 2', the curved structures of the electrical components 1, 2 rise approximately vertically from the circuit board 3 and then turn horizontally again at a similar height to each other. An insulating element 4 is attached to the underside of the electrical component 2, so that a joint leakage of the electrical components 1, 2 does not cause an electrical coupling of both electrical components 1, 2.

[0020] FIG. 4 shows an electro-technical arrangement 10 according to a first exemplary embodiment of the invention, in which the edge side of the circuit board 3 is surrounded by an insulating element 4 by injection. In this way, the insulating element 4 electrically insulates the voltage on the possibly upper side 3a of the circuit board 3 against the voltage on the possibly lower side (not shown). The insulating element 4 has a maximum height H in order to provide a relatively large insulation distance from the upper side 3a to the lower side. This reduces any possible surface leakage currents. A protruding piece 4a is also formed from the insulating element 4, which connects the mutually facing edges of the circuit board 3 with each other, thus facilitating the electrical insulation of the two areas of the surface 3a of the circuit board 3. According to the invention, a first side 5 is provided, which, together with a perpendicular side opposite to the side 5 in the Y direction, forms a funnel-shaped positioning part. Thus, a structure inserted into this funnel-shaped catch in the negative Z direction will reach a specific target position, and for this purpose it will not be necessary to guide the electrical component from the outside. In other words, the side surface 5 or the funnel-shaped catch defined by the side surface 5 defines a target final position, in particular in the Y direction. The same applies to the additional side surface 6, which defines a slope descending in the X direction. The additional side surface 6, together with the corresponding opposite side surface (not shown), can therefore define a predefined target position in the X direction of the electrical component 1, 2 to be connected to the circuit board 3. The orientation of the side surface 5 and the additional side surface 6 with respect to the Z axis is mathematically oriented at 90° negative rotation to each other. The same applies to the respective funnel-shaped catch or cutout occurring in conjunction with the side surface 5 or the additional side surface 6. Of course, the side surface 5 and the additional side surface 6 can also be combined with each other in one common funnel-shaped catch, so that one and the same structure of one electrical component 1, 2 is guided to its final position both by the side surface 5 and by the additional side surface 6. The bottom of the respective funnel-shaped catch is covered by a flat layer of the insulating element 4 in the form of a bottom structure. At this point, the circuit board is insulated on the surface, which can further suppress or reduce surface leakage current from the surface area 3a of the circuit board 3 to the further surface area 3b of the circuit board 3.In particular, if the insulating element 4 comprises an elastic material, the bottom structure 7 allows the electrical components 1, 2 to be preloaded in their final position towards the circuit board 3. This makes it possible to avoid vibrations causing annoying noises.

[0021] The width of the side surface 5 or the additional side surface 6 may be in the range between 2 mm and 20 mm, preferably between 3 and 15 mm, very preferably between 5 and 10 mm. This width relates to the dimension of the side surface 5 or the additional side surface 6 that runs perpendicular to the downward direction.

[0022] 5 shows a perspective view of an alternative exemplary embodiment of an electro-technical arrangement 10 according to the invention. A part 2 made from stamped sheet metal has in this case two overhangs which are bent twice in opposite directions at right angles, corresponding to the contact arrangement 9 shown in connection with FIG. 3, and are mechanically and electrically connected to the substrate 3. Two structures 2a, 2b protruding from the vertical areas of the overhangs are guided to their target positions by funnel-shaped catches with their respective side faces 5, so that the structures 2a, 2b are already positioned exactly and precisely on the circuit board 3 before fastening in the X and Y directions.

[0023] FIG. 6 shows a cross-section of the arrangement shown in FIG. 5, from which one can see a cross-section of the insulating element 4 in the region of the contact between the projection of the electrical component 2 and the circuit board 3. In other words, this cross-section is made substantially to correspond to the position of the double arrow X in FIG. 5. The region of the insulating element 4 which surrounds the circuit board 3 at the edge surrounds the underside of the circuit board 3 with a relatively flat structure, while in the region of the upper side of the circuit board 3 the insulating element 4 forms side surfaces 5 according to the invention for guiding and positioning the structures 2a, 2b of the electrical component 2 substantially without play. In the X direction the punched part tolerances are depicted by the double arrow X1, while the tool tolerances are illustrated by X2. By dimensioning X1 relative to X2 the tolerances in the final position of the electrical component 2 can be predefined. The region of the insulating element 4 which is arranged in the middle on the circuit board 3 has two additional side surfaces 6 which, together with the outer side surfaces 5, provide for a precise positioning of the electrical component 2 on the circuit board 3.

[0024] Also in the Y direction, the punched parts and the dies have their own manufacturing tolerances (sample standard deviations) and mutual tolerances. In other words, the thickness of the punched parts (Y1) may differ or vary with respect to the opening of the V-notch, which may bring about or threaten precise positioning.

[0025] 7 shows a cross-sectional side view of the exemplary embodiment of the electro-technical arrangement 10 shown in FIG. 5. In this exemplary embodiment, the (not shown) structures of the substantially vertical sections of the electric components 1, 2 are arranged in respective funnel-shaped catches between two oppositely inclined side surfaces 5 and are thus fixed in position relative to the circuit board 3. The electric component 1 transitions from a horizontal fixing ledge fixed on the conductor track 12 to the substantially vertical structure discussed above. A re-bend of approximately 90° makes the electric component 1 horizontal, so that in this region it runs parallel to the circuit board 3. The same applies to the second electric component 2, which, in its upper horizontal region, has a slope of approximately 40° to the horizontal. The two electrically mutually insulated conductor sections 12 are separated from each other by one structural part of the insulating element 4, so that the surface leakage current distance between the conductor sections 12 is significantly longer for a horizontal connection (e.g. along the surface of the circuit board 3).

[0026] Figure 8 shows an enlarged view of the left edge region of the electro-technical arrangement 10 introduced in Figure 6, from which it can be seen that the surface leakage current distance 11 between the structural part 2a of the electrical component 2 and the underside of the circuit board 3 has been considerably increased. Moreover, both the circuit board 3 and the insulating element 4 are enclosed in a housing 8. In the case of pre-positioning the circuit board 3 and the electrical component 2 in the housing 8, the injection molding process during the production of the insulating element 4 can fix and / or clamp and / or glue said parts in the housing 8. In this case, additional screwing or other fixings can preferably be dispensed with.

[0027] FIG. 9 shows the steps of one exemplary embodiment of the method for manufacturing an electro-technical mechanism according to the invention. The electro-technical mechanism can be or can be included in an electrical control device. In a first step 100, the circuit board is injection-surrounded with insulating elements. In particular, the edge side of the circuit board is injection-surrounded with insulating elements. The insulating elements can be or contain foamed plastic. In this way, fixing of the circuit board at its outer edge by means of insulating elements is also possible. Then, in step 200, the electric component is placed on the circuit board. The component is guided in the course of moving in the direction Z (perpendicular to the surface of the circuit board) towards the circuit board. In order to keep the handling effort of the electric component low, the electric component is aligned with respect to the circuit board in the direction X and / or in the direction Y oriented perpendicular to the direction Z by the side of the insulating element made at an angle to the direction Z. In other words, the electrical component slides, if necessary, along this side of the insulating element to a position closest to the circuit board, where it remains as specified and is electrically and / or mechanically coupled to the circuit board. The component is then mechanically and electrically coupled to the circuit board in step 300. In this case, material- and / or form- and / or friction-type coupling methods may be used. Galvanic coupling, optionally friction welding, soldering or sintering, among others, may be used.

Claims

1. a circuit board (3), - an electrical component (1, 2), an insulating element (4), The circuit board (3) is surrounded by the insulating element (4), the insulating element (4) has a side (5) aligned at an angle with respect to a direction Z defined perpendicular to the surface of the circuit board (3); and The electrical components (1, 2) are fixed on the circuit board (3) at the base of the side surface (5) of the insulating element (4); An additional side surface (6) is further provided, and the additional side surface (6) is - forming a funnel together with said side surface (5), and / or an electro-technical mechanism (10) arranged rotated substantially by 90 degrees around Z relative to said side surface (5);

2. 2. An electro-technical system according to claim 1, characterized in that the electrical components (1, 2) have stamped parts, in particular conductor tracks, and that the electrical components (1, 2) are adapted to slide along the side surface (5) of the insulating element (4) to the root of the side surface (5) before fastening during the manufacturing process of the electro-technical system (10).

3. 3. An electro-technical arrangement according to claim 1 or 2, wherein the thickness (H) of the insulating element (4) above the surface of the circuit board (3) in the region of the side surfaces (5) is at least 3 mm, preferably 30 mm.

4. 4. An electro-technical system according to any one of claims 1 to 3, wherein the insulating element (4) is provided as an electrical insulator in the electro-technical system (10), in particular between a first surface (3a) of the circuit board (3) and a second surface (3b) of the circuit board (3) facing the first surface.

5. The side surface (5) - formed as a draft angle and / or - components, namely - a component of the funnel-shaped catch or - is a component of a V-notch, Electro-technical arrangement according to any one of claims 1 to 4.

6. Electro-technical arrangement according to any one of claims 1 to 5, wherein the side surface (5) has an angle of 5° to 50°, preferably 10° to 45°, particularly preferably 12° to 40° with respect to the direction Z.

7. Between the additional side surface (6) and the side surface (5), - there is provided a bottom structure (7) of the insulating element (4) which covers the surface of the circuit board (3), and / or - one structural part of said electrical components (1, 2) is sandwiched; Electro-technical arrangement according to any one of claims 1 to 6.

8. A method for manufacturing an electro-technical arrangement, comprising the steps of: - surrounding (100) the circuit board (3) by injection molding of an insulating element (4), a step (200) of placing the electrical components (1, 2) on the circuit board (3), in which the electrical components (1, 2) are aligned with respect to the circuit board (3) in a direction X and / or a direction Y oriented perpendicular to the direction Z by the side surfaces (5) of the insulating elements (4) formed at an angle to the circuit board (3) in the course of moving in a direction Z perpendicular to the surface of the circuit board (3), The electro-technical mechanism is formed to include an additional side (6), the additional side (6) comprising: - forming a funnel together with said side surface (5), and / or - positioned substantially 90 degrees rotated about Z relative to said side surface (5).

9. The method according to claim 8, further comprising a step (300) of mechanically and electrically, in particular galvanically, coupling (1, 2) said electrical components (1, 2) to said circuit board (3), preferably by friction welding and / or sintering and / or soldering.

10. 10. The method according to claim 8 or 9, wherein the insulating element (4) remains within the electro-technical arrangement during intended use of the electro-technical arrangement.

11. 11. The method according to claim 8, wherein the electrical component (1, 2) has a stamped part, in particular a conductor track, and the electrical component (1, 2) slides along the side surface (5) of the insulating element (4).

12. 12. The method according to any one of claims 8 to 11, wherein the thickness (H) of the insulating element (4) above the surface of the circuit board (3) in the region of the side surfaces (5) is at least 3 mm, preferably 30 mm.

13. 13. The method according to any one of claims 8 to 12, wherein the insulating element (4) is used as an electrical insulator in the electro-technical arrangement (10), in particular between a first surface (3a) of the circuit board (3) and a second surface (3b) of the circuit board (3) facing the first surface (3a).

14. The aspect is - formed as a draft angle and / or - components, namely - a component of the funnel-shaped catch or - is a component of a V-notch, 14. The method according to any one of claims 8 to 13.

15. 15. The method according to any one of claims 8 to 14, wherein the side surface (5) has an angle of 5° to 50°, preferably 10° to 45°, particularly preferably 12° to 40° with respect to the direction Z.

16. An electronic control device comprising an electro-technical arrangement (10) according to any one of the preceding claims.

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