Pre-assembly for an electronic assembly and electronic assembly

Abstract

The invention relates to a pre-assembly (1) for an electronic assembly (30), comprising: a printed circuit board (2), at least one electronic component (3) arranged on the printed circuit board (2) and electrically contacted, a retaining frame (5) for thermal contacting the at least one electronic component (3) with a heat sink (31), wherein the retaining frame (5) has a receptacle (6) for the at least one electronic component (3), wherein the retaining frame (5) further comprises at least one spring element (12) which is slidably guided on the retaining frame (5) in the direction of a sliding axis between a first position and a second position, wherein the spring element (12) is arranged at a distance from the component (3) in the first position and resiliently contacts the component (3) in the second position.

Description

[0001] The present invention relates to a pre-assembly for an electronic assembly comprising at least one printed circuit board and at least one electrically contacted electronic component arranged on the printed circuit board. It further relates to an assembly comprising the pre-assembly and a heat sink.

[0002] It is known to dissipate heat from high-power electronic components using a heat sink, where the component is pressed against the heat sink by a spring force. Such components are often through-hole mounted on a printed circuit board (PCB), meaning they have connection pins that are soldered into plated sockets on the PCB to establish electrical and mechanical contact between the component and the board.

[0003] The problem is that the solder joint between the connection pins and the circuit board is relatively stiff and stress-sensitive, and that the spring clamping, which is achieved, for example, via a clip mounted before or after soldering the component, requires sufficient spring travel to generate enough clamping force between the component and the heat sink, despite any component height tolerances. Therefore, the connection pins are often chosen to be so large in their lateral dimensions that vertical relative movement results in only very low stress loads at the solder joint. However, this leads to increased installation space requirements and other disadvantages such as interference inductances.

[0004] Since the clamping is done afterwards, sequential screwing operations can also lead to tilting of the component.

[0005] To reduce stress on the solder joints, the connection pins are often soldered only after the complete module, consisting of the circuit board, component, retaining spring, and heat sink, has been installed. The product housing is often used as the heat sink, and its dimensions are so large that soldering in the installed state is only possible with small product dimensions and low complexity. In cases where a second circuit board is placed over the first, the solder joint is no longer accessible. Soldering the pins after the module is installed is then out of the question anyway.

[0006] Document EP 3 975 678 B1 discloses a holding device for thermally contacting an electronic component mounted on a printed circuit board with a heat sink, wherein the holding device comprises a holding body, a spring element and a clamping element, wherein the holding body forms a cavity corresponding to the electronic component for receiving the electronic component and has a connection section as well as a thermally conductive heat-conducting section adjacent to the cavity with a thermal connection surface facing away from the cavity, wherein the clamping element is configured to clamp the spring element, wherein the spring element is configuredto brace itself in a tensioned state against a counter-holding element and to exert a force on the holding body and / or the component to be received in the cavity of the holding body and to move the holding body with the connection surface to the heat sink and / or to press it against the heat sink.

[0007] Document DE 101 29 788 B4 apparently describes a plastic frame for mounting an electronic high-current control unit with recesses for the precise positioning of busbars, a circuit board and electrical / electronic components, as well as a potting compound for encasing the components, and with molded snap elements for connection to a heat sink.

[0008] Document DE 101 54 878 B4 discloses a retaining element for fixing at least one electronic power component arranged on a printed circuit board to a heat sink, with an elastic element by which the electronic power component can be pressed against the heat sink, wherein the retaining element can be positioned in a component placement direction on the printed circuit board and the compressive force of the elastic element acts transversely to the component placement direction on the electronic power component, wherein one or more retaining feet are provided for fixing to the printed circuit board and the retaining element is designed so that it can be fixed to the printed circuit board in the same way as an electronic circuit element.

[0009] Document WO 2023 / 083 823 A1 discloses a printed circuit board arrangement comprising a printed circuit board with a top and a bottom, at least one electrical component arranged on the bottom of the printed circuit board, a heat sink, and a retainer, wherein the retainer presses the printed circuit board against the heat sink. The retainer is spring-loaded and exerts a spring force on the printed circuit board.

[0010] It is therefore an object of the present invention to provide a pre-assembly for an electronic assembly whose connection pins are soldered to a printed circuit board as early as possible in the assembly process, but which can be connected to a heat sink without stress.

[0011] According to one aspect of the invention, a pre-assembly for an electronic assembly is provided, comprising a printed circuit board and at least one electronic component arranged on the printed circuit board and electrically contacted. The pre-assembly further comprises a mounting frame for thermally contacting the at least one electronic component with a heat sink, the mounting frame having a receptacle for the at least one electronic component. The mounting frame further comprises at least one spring element which is slidably guided on the mounting frame in the direction of a sliding axis between a first position and a second position, wherein the spring element is arranged spaced apart from the component in the first position and resiliently contacts the component in the second position.

[0012] The pre-assembly therefore includes the mounting frame as a separate component, which enables stress-free thermal contact with a heat sink that will later be connected to the pre-assembly to form an electronic assembly. This is achieved by the mounting frame having at least one spring element that can be positioned in at least two positions: a first position in which it is spaced apart from the component, meaning it does not contact the component and therefore exerts no force on it; and a second position in which it makes spring contact with the component, i.e., is in contact with the component and exerts a spring force on it. The spring element is designed such that the spring force is exerted in the direction of the heat sink to be mounted, and thus, in particular, away from the circuit board.

[0013] Specifically, the spring element is designed to be moved into the second position only after the component has been soldered to the circuit board and the pre-assembly is connected to the heat sink. Tensioning the spring and thus building up the contact force between the component and the heat sink requires only a shift of the spring element from the first to the second position. This is possible even if the electronic assembly is installed in a difficult-to-access location. Furthermore, the build-up of spring force can be achieved with relatively little stress on the solder joints.

[0014] This makes it possible to solder the pre-assembly without a separate mechanical clamping device and then clamp it to a heat sink in a single clamping operation after assembly. This eliminates the need for a clamping device during the soldering process. Furthermore, the clamping process is very simple and occurs uniformly after assembly is complete, thus reducing component stress.

[0015] According to one embodiment, the at least one spring element is designed as a flat spring sheet with at least one spring tongue that protrudes from the plane of the spring sheet in the first position and is pressed into the plane of the spring sheet in the second position.

[0016] Such a spring element is very simple in design, cost-effective and robust, and can be moved particularly easily from the first position to the second position.

[0017] If the pre-assembly has more than one electronic component, the mounting frame has, in particular, a receptacle for each electronic component.

[0018] If the pre-assembly contains several electronic components, a spring tongue can be provided for each of these components. In this case, the spring element is then constructed as a single piece and can, for example, be stamped from a sheet of metal, but it has multiple spring tongues. Alternatively, several separate spring elements can be provided for the individual electronic components, arranged in such a way that they abut each other during the sliding process and are moved together.

[0019] According to one embodiment, at least one component is arranged on a support of the retaining frame and the support has a recess through which, in the second position of the spring element, the spring element is pressed against the component.

[0020] In this embodiment, the mounting frame can have a base plate with a bottom surface facing the circuit board and a top surface facing the electronic component, with the spring element resting on and guided on the top surface. In the area of ​​the electronic component, the mounting frame has a support on its top surface, for example, in the form of a support surface interrupted by the recess, on which the component rests. Through the recess, the spring element can contact the component and press it against the heat sink arranged above it.

[0021] The electronic component is mounted on the circuit board, in particular by through-hole mounting, and soldered to metallized contacts of the circuit board.

[0022] According to one embodiment, the spring element is slidably guided in a guide channel of the mounting frame. This guide channel has openings in one side that correspond to the recesses already described. The guide channel allows for secure guidance of the spring element parallel to the plane of the circuit board without the risk of tilting or jamming.

[0023] According to the invention, the spring element has at least one elongated hole, which is arranged, in particular, at one end of the spring element. The longitudinal axis of the elongated hole lies in the plane of the spring element and is oriented perpendicular to the sliding axis of the spring element.

[0024] The assembly further comprises an actuating tool with a longitudinal axis and an end face, as well as a pin arranged on the end face at a distance r from the longitudinal axis and extending from the end face in the direction of the longitudinal axis, which can be engaged with the elongated hole. The spring element can be displaced along its sliding axis by means of the pin engaging with the elongated hole by rotating the actuating tool 180° about its longitudinal axis by a distance 2r.

[0025] The actuating tool is designed to move at least one spring element from its first position to the second position. The actuating tool allows the spring element to be moved even when the assembly is only partially accessible. The spring is tensioned by the actuating tool by inserting the pin into the elongated hole and rotating the actuating tool around its longitudinal axis. This causes the pin to engage the spring element and slide within the elongated hole, thus converting the rotational movement of the actuating tool into a transverse movement of the spring element.

[0026] The actuating tool can then be removed and therefore no longer needs to be part of the electronic assembly after the pre-assembly has been completed.

[0027] It is not conceivable according to the invention to displace the spring element using another actuating element, in particular using an actuating element that engages with or in the spring element and is displaced laterally together with it.

[0028] According to one embodiment, the pre-assembly further comprises at least one locking element for locking the spring element in its second position on the mounting frame. The locking element can be arranged on the mounting frame and / or on the spring element.

[0029] This embodiment has the advantage that the spring element is easily held in its second position after tensioning, which is intended as the final position of the spring element. At the same time, however, it is possible to return the spring element to its first position if necessary by releasing the locking mechanism.

[0030] According to one embodiment, the pre-assembly further comprises at least one spacer arranged on the side of the mounting frame facing the circuit board. This defines and stabilizes the position of the mounting frame on the circuit board and prevents bending of the mounting frame – particularly when multiple spacers are appropriately positioned.

[0031] According to one embodiment, the mounting frame is made up of a plurality of modules, because each module has a mounting frame section with a receptacle for an electronic component.

[0032] In this embodiment, the mounting frame is not constructed from a single piece to accommodate multiple electronic components, but rather consists of several separate modules, each with a recess for an electronic component, which are assembled to form the mounting frame. This has the advantage that the size of the mounting frame can be flexibly adapted to the number of electronic components. The modules can, in particular, be snapped together or connected to each other in some other way.

[0033] The heat sink can be attached to the mounting frame and / or the circuit board, for example, by screws, for which the heat sink may have blind holes. The screws can be used to fasten the heat sink to both the circuit board and the mounting frame simultaneously, meaning the same screws can secure the heat sink to both. However, it is also possible to provide separate screw connections for the heat sink to the circuit board and the mounting frame, allowing for more flexible placement of the screw points.

[0034] According to a further aspect of the invention, an electronic assembly is specified, comprising the described pre-assembly and furthermore a heat sink, wherein the heat sink is attached to the mounting frame and / or the circuit board.

[0035] The electronic assembly offers the advantages already described in connection with the pre-assembly.

[0036] According to one embodiment, the at least one spring element is in its second position and presses the at least one component against the heat sink. Thus, the spring element is tensioned and exerts a spring force on the electronic component in the direction of the heat sink. In this embodiment, the electronic assembly is already fully assembled, and the spring element is tensioned to establish thermal contact between the component and the heat sink.

[0037] According to one embodiment, a thermally conductive, electrically insulating medium is arranged between the heat sink and the at least one component. In particular, an insulating film, a thermally conductive film, an adhesive, or a thermal paste can be applied to the heat sink before installation. A combination of insulating film and thermal paste is also possible.

[0038] The assembly of the module can be carried out in particular according to the following procedure: First, the mounting frame is populated with the electronic components and connected to the circuit board. The electronic components are then through-hole mounted on the circuit board. The spring element is in its first, load-free position. This forms the pre-assembly.

[0039] The connection pins are then soldered into the plated sockets of the circuit board. The pre-assembly is then connected to the heat sink in one of the ways described to form the electronic assembly. Finally, the spring element is tensioned using the actuating tool to press the components against the heat sink.

[0040] Embodiments of the invention are described below by way of example with reference to schematic drawings. Fig. Figure 1 shows a perspective view of a mounting frame for a front assembly according to an embodiment of the invention, Fig. Figure 2 shows a perspective, partially cutaway view of the mounting frame according to Fig. 1, Fig. Figure 3 shows further details of the mounting frame according to the Fig. 1 and Fig. 2, Fig. 4 shows the one in Fig. 3. Excerpt of the mounting frame shown from an underside, Fig. Figure 5 shows a side view of a spring element, Fig. Figure 6 shows a top view of the spring element according to Fig. 5, Fig. Figure 7 shows an actuating element for displacing the spring element according to the Fig. 5 and Fig. 6 according to an embodiment of the invention, Fig. Figure 8 shows a sectional view of the actuating element according to Fig. 7 in a first position, Fig. Figure 9 shows a sectional view of the actuating element according to Fig. 7 in a second position, Fig. Figure 10 shows a section of the mounting frame according to the Fig. 1 to 4 with operating tool inserted, Fig. Figure 11 shows a perspective view of a pre-assembly with a holding frame according to an embodiment of the invention, Fig. Figure 12 shows an electronic assembly according to an embodiment of the invention, Fig. Figure 13 shows the electronic assembly according to Fig. 12 at a different stage of assembly, Fig. Figure 14 shows the electronic assembly according to the Fig. 12 and Fig. 13 at a further stage of assembly, Fig. 15 shows the electronic assembly according to the Fig. 12 to 14 in a further stage of assembly, Fig. Figure 16 shows a sectional view through the assembly according to an embodiment of the invention, Fig. Figure 17 shows a sectional view through the assembly according to a further embodiment of the invention, Fig. Figure 18 shows a perspective view of modules that can be assembled to form a support frame and Fig. Figure 19 shows a perspective view of the modules according to Fig. 18 after assembly.

[0041] Elements of the same construction or function are provided with the same reference symbols across all figures.

[0042] The retaining frame 5 according to Fig. 1 is a component of a pre-assembly according to an embodiment of the invention. It has a base plate 8 with a top surface 9 and a Fig. 1. The underside is not visible. On the top side 9, a number of recesses 6 for electronic components 3 are arranged. The electronic components 3 can be, for example, power semiconductor components that exhibit a relatively high power dissipation during operation and therefore require cooling. The heat is dissipated primarily via the surfaces 7 of the electronic components 3, which are to be brought into thermal contact with a heat sink (not shown in the figure).

[0043] For electrical contacting of the electronic components 3, in the illustrated embodiment these each have three connection pins 4 which are contacted on a circuit board not shown in the figure.

[0044] Fig. Figure 2 shows a 180° rotated view of the mounting frame 5 according to Fig. 1. In this view, it can be seen that a channel 11 is formed between the electronic components 3 and areas of the mounting frame 5, in which a spring element 12 or a number of spring elements 12 slide. The spring element 12 has a number of spring tongues 22, each associated with an electronic component 3, and an elongated hole 23, which is arranged at one end of the spring element 12.

[0045] The spring element 12 can slide through the channel 11 in the direction indicated by arrow P. Thus, arrow P designates a sliding axis of the spring element 12. The spring element 12 is displaceable in the channel 11, in particular between a first position, which is in Fig. 2 is shown, and a second position. In the Fig. In the first position shown in Figure 2, the spring element 12 is arranged at a distance from the electronic components 3, i.e., a gap is formed between the electronic components 3 and the spring element 12. However, if the spring element 12 is moved to the right in the channel 11 towards the stop 33, the spring tongues 22 are pushed into the channel 11 and brought into contact with the electronic components 3. In this second position, the spring tongues 22 exert a force on the electronic components 3.

[0046] The elongated hole that is in Fig. 2, which is only partially shown, has a longitudinal axis that lies in the plane of the spring element 12 and is oriented perpendicular to the sliding axis of the spring element 12.

[0047] The spring element 12 can in particular be made of spring steel or of a CuSn or CuNi alloy.

[0048] Fig. Figure 3 shows further details of the mounting frame 5. Within the receptacle 6 for the electronic components 3, support surfaces 10 are formed on which the electronic components 3 rest. Below the support surfaces 10, the channel 11 for the spring element 12 is formed. In the embodiment shown, the spring element 12 is guided between the receptacles 6 by sliding tabs 16.

[0049] The arrangement and number of the recordings 6 depend on the type of assembly to be formed and can be designed flexibly.

[0050] The retaining frame 5 also has an opening 15 into which an actuating tool for moving the spring element 12 can be inserted. This is explained further below. Furthermore, a locking element 14 is provided on the retaining frame 5, by means of which the spring element 12 can be locked in its second position.

[0051] The mounting frame 5 also has mounting sleeves 17 for connecting the mounting frame 5 to a printed circuit board (not shown in the figure) and / or a heat sink. Furthermore, spacers 18 are provided on the underside of the mounting frame 5 to create a defined distance to the printed circuit board.

[0052] Fig. Figure 4 shows a view of the underside 19 of the mounting frame 5 and in particular of the cutout from the mounting frame 5, which is in Fig. Figure 3 shows that the base plate 8 of the mounting frame has 5 through holes 20 for the connection pins of the electronic components 3.

[0053] Fig. Figure 5 shows the spring element 21 with the spring tongue 22 protruding from the plane of the spring element 12 in a side view.

[0054] Fig. Figure 6 shows a top view of the in Fig. 5 Spring element 12 shown. The spring element 12 can, in particular, be stamped from a sheet metal part. It can be formed in one piece and, in the case of several electronic components 3, have a spring tongue 22 for each electronic component 3. However, several spring elements 12 can also be inserted one after the other in the direction of the sliding axis in the retaining frame 5.

[0055] Fig. Figure 7 shows the actuating element 24 for tensioning the spring element 12. The actuating element 24 has a longitudinal axis L and a flat end face 25 from which a pin 26 protrudes and extends parallel to the longitudinal axis L. The pin 26 is radially distance r from the longitudinal axis L.

[0056] Fig. Figure 8 shows the actuating tool 24 inserted into the opening 15 in the retaining frame 5. Fig. In position 8, the actuating element 24 is in a first position, which also corresponds to a first, untensioned position of the spring element 12. The pin 26 engages in the elongated hole 23 in the spring element 12.

[0057] Rotating the actuating tool 24 about its longitudinal axis L causes the pin 26 to engage the spring element 12. Since the electronic components 3 are each held in their receptacles 6, the movement of the spring element 12 is not transmitted to the components 3. They are thus secured against slippage.

[0058] Fig. Figure 9 shows the position of the actuating tool 24 and the spring element 12 after a rotation of the actuating tool 24 by 180°. The spring element 12 was thereby displaced by the distance 2r. The locking element 14 then engages behind the spring element 12 to prevent it from slipping back.

[0059] Fig. Figure 10 shows a view of the retaining frame 5 from its upper side 9. The actuating tool 24 and the spring element 12 are in the second position, in which the spring element 12 has been moved so far that the locking element 14 engages behind it and the spring tongue 22 comes to rest in a recess 27 of the receptacle 6.

[0060] In the Fig. For the sake of clarity, electronic component 3 has not been shown in the view 10.

[0061] The stop 33 and the locking element 14 provide a mechanically releasable locking mechanism for the sliding spring formed by the at least one spring element 12 in the fully assembled state. If repair of the assembly becomes necessary, the locking element 14 is pressed back into the retaining frame 5 through an opening, allowing the spring element 12 to be moved back into its untensioned first position by the actuating tool 24.

[0062] Fig. Figure 11 shows a pre-assembly 1 with several electronic components 3 arranged in the mounting frame 5, which are through-mounted onto a printed circuit board 2. The printed circuit board 2 is located adjacent to the underside of the mounting frame 5 and has metallized sleeves 28 for the connection pins 4.

[0063] Fig. Figure 12 shows a section through a subassembly 30 with the pre-assembly 1 according to Fig. 11. The pre-assembly 1 is connected to a heat sink 31, which is mounted on the surfaces 7 of the electronic components 3 to dissipate heat. The heat sink 31 can be the housing of a product or a separate heat sink.

[0064] The heat sink 31 can have a multi-layered construction and be cooled with a cooling medium such as water or a glycol / water mixture. It can be provided with steps of varying heights, several millimeters high, in the area of ​​the components 3, to accommodate components 3 of different heights with the same tolerance relative to the spring element 12. The height difference between different component designs can be several millimeters.

[0065] The electronic components 3 are, for example, diodes or other semiconductor devices in TO247 or TO220 packages. Such components have a height tolerance of approximately 0.2 mm. Further tolerances that must be taken into account arise, for example, from the flatness of the mounting frame 5. The resulting maximum gap is compensated for by the pressing force of the spring element 12.

[0066] In the embodiment shown, the connection between the heat sink 31 and the circuit board 2 and the mounting frame 5 is made via screws 32, which are inserted into the mounting sleeves 17 and corresponding blind holes in the heat sink 31.

[0067] Fig. Figure 12 shows the assembly 30 with the spring element 12 in the first, untensioned position.

[0068] Fig. Figure 13 shows a perspective view of the assembly 30 with the actuating tool 24 removed. In the first position of the spring element 12 shown, a portion of the spring element 12 is exposed in the opening 15.

[0069] This illustration shows that the heat sink 31 has blind holes 35 for each mounting point on the circuit board or the mounting frame, into which the screws can be inserted.

[0070] Fig. Figure 14 shows a sectional view through assembly 30, in which the spring element 12 has been moved into the second, tensioned position by rotating the actuating tool 24. In this position, the spring tongues 22 press the electronic components 3 with their surface to be cooled (e.g., heat slug) against the heat sink 31, thus ensuring particularly good heat transfer. The spring element 12 was moved until it reached its stop 33.

[0071] Fig. Figure 15 shows the assembly 30 with tensioned spring element 12, which is therefore no longer or practically no longer free in the opening 15 because it has been moved to the right from this area.

[0072] The Fig. 16 and Fig. Figure 17 shows two different variants of the connection between the circuit board 2, the mounting frame 5 and the heat sink 31 for the assembly 30.

[0073] At the in Fig. In the embodiment shown in Figure 16, the heat sink 31 has blind holes 35 which correspond to mounting sleeves 17 of the mounting frame 5 and which, like the mounting sleeves 17, may have internal threads into which screws 32 are inserted to connect the circuit board 2, the mounting frame 5 and the heat sink 31 at each mounting point.

[0074] At the in Fig. In contrast, in the embodiment shown in Figure 17, the mounting frame 5 does not have any mounting sleeves 17. The screws 32 engage directly in the blind holes 35 of the heat sink 31 and fasten the circuit board 2 to the heat sink 31. The mounting frame 5, on the other hand, is connected to the circuit board 2 by means of several snap hooks 36, which have corresponding through-holes for this purpose.

[0075] In the Fig. 16 and Fig. Figure 17 also shows a thermal interface material 34 between the electronic component 3 and the heat sink 31. The thermal interface material 34 is intended to provide particularly good heat transfer between the electronic component 3 and the heat sink 31 while simultaneously providing electrical insulation. Instead of the thermal interface material 34, a layer of a TIM (thermal interface material) or of a highly thermally conductive adhesive, or a combination thereof, can also be used.

[0076] The Fig. 18 and Fig. Figure 19 shows a variant of the mounting frame 5, in which it is composed of individual modules 37. Each module 37 is suitable for receiving an electronic component 3 and thus has a receptacle 6 for the electronic component. The individual modules 37 can be connected to one another via interlocking guide rails 38. Locking hooks 39, which engage in a groove 40 of the adjacent module 37, hold the modules 37 together after they have been inserted into one another.

[0077] Fig. Figure 18 shows the modules 37 before the connection, Fig. Figure 19 shows the interconnected modules 37.

[0078] The Fig. 18 and Fig. Figure 19 shows only two modules 37. In this embodiment, however, it is possible to flexibly assemble the holding frame 5 from any number of modules 37 as required. Reference symbol list 1 Front assembly 2 circuit boards 3 electronic component 4 connection pins 5 mounting frames 6 recording 7 Surface 8 Base plate 9 Top 10 contact surface Channel 11 12 spring element 14 Locking element 15 Opening 16 sliding tab 17 Mounting sleeve 18 spacers 19 Subpage 20 through holes 22 Spring tongue 23 Slotted Hole 24 Actuating tool 25 Front 26 pens 27 recess 28 Sleeve 30 assembly 31 heat sinks 32 screw 33 attacks 34 Thermal conductive film 35 blind hole 36 snap hooks Module 37 38 guide rails 39 locking hooks 40 Nut L Longitudinal axis r distance

Claims

[1] Pre-assembly (1) for an electronic assembly (30), comprising - a circuit board (2), - at least one electronic component (3) arranged on the circuit board (2) and electrically contacted, - a holding frame (5) for thermally contacting the at least one electronic component (3) with a heat sink (31), wherein the holding frame (5) has a receptacle (6) for the at least one electronic component (3), wherein the holding frame (5) further has at least one spring element (12) which is guided on the holding frame (5) in the direction of a sliding axis between a first position and a second position, wherein the spring element (12) is arranged at a distance from the component (3) in the first position and resiliently contacts the component (3) in the second position. [2] Pre-assembly (1) according to claim 1, wherein the at least one spring element (12) is designed as a flat spring plate with at least one spring tongue (22) which protrudes from the plane of the spring plate in the first position and is pressed into the plane of the spring plate in the second position. [3] Pre-assembly (1) according to claim 1 or 2, wherein the at least one component (3) is arranged on a support of the holding frame (5) and the support has a recess (27) through which, in the second position of the spring element (12), the spring element (12) is pressed against the component (3). [4] Pre-assembly (1) according to one of claims 1 to 3, wherein the electronic component (3) is mounted on the circuit board (2) by means of a through-hole connection and is soldered to metallized contacts of the circuit board (2). [5] Pre-assembly (1) according to one of claims 1 to 4, wherein the spring element (12) is displaceably guided in a guide channel (11) of the holding frame (5). [6] Pre-assembly (1) according to one of claims 1 to 5, wherein the spring element (12) has at least one elongated hole (23) whose longitudinal axis lies in the plane of the spring element (12) and is oriented perpendicular to the sliding axis, wherein the pre-assembly (1) further comprises an actuating tool (24) having a longitudinal axis L and an end face (25) and a pin (26) arranged on the end face (25) at a distance r from the longitudinal axis L and extending from the end face (25) in the direction of the longitudinal axis L, which pin can be brought into engagement with the elongated hole (23), wherein the spring element (12) is displaceable by means of the pin (26) engaging with the elongated hole (23) by rotating the actuating tool (24) by 180 degrees about its longitudinal axis L by the distance 2r along its sliding axis. [7] Pre-assembly (1) according to one of claims 1 to 6, further comprising at least one locking element (14) for locking the spring element (12) in its second position on the holding frame (5). [8] Pre-assembly (1) according to one of claims 1 to 7, further comprising at least one spacer (18) arranged on the side of the holding frame (5) facing the printed circuit board (2) to the printed circuit board (2). [9] Pre-assembly (1) according to one of claims 1 to 8, wherein the holding frame (5) is constructed from a plurality of modules (37), each module (37) having a holding frame section with a receptacle (6) for an electronic component (3). [10] Electronic assembly (30), comprising a pre-assembly (1) according to one of claims 1 to 9 and further a heat sink (31), wherein the heat sink (31) is fastened to the holding frame (5) and / or the printed circuit board (2). [11] Electronic assembly (30) according to claim 10, wherein the at least one spring element (12) is in its second position and the at least one component (3) presses against the heat sink (31). [12] Electronic assembly (30) according to claim 10 or 11, wherein a heat-conducting, electrically insulating medium is arranged between the heat sink (31) and the at least one component (3).

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