Electronic assembly and method for manufacturing the electronic assembly

Abstract

The invention relates to an electronic assembly comprising at least one main circuit board (5) and at least one electronic subassembly, wherein the electronic subassembly comprises at least one circuit board (1) having a first main surface (6) and a second main surface (7) arranged parallel to and opposite each other, wherein the circuit board (1) has at least one electronic component (2) on its first main surface (6), wherein the circuit board (1) of the electronic subassembly is arranged on the main circuit board (5) by means of a press-fit connection (4) and projects from it at approximately a 90-degree angle, wherein a conductive element (3) is arranged on the first main surface (6) which has a longer extent along a surface normal on the first main surface (6) than the electronic component (2). The invention also relates to a method for manufacturing an electronic assembly.

Description

Technical area

[0001] The invention relates to an electronic assembly comprising at least one main circuit board and at least one electronic subassembly. The electronic subassembly comprises at least one circuit board having a first main surface and a second main surface arranged parallel to and opposite one another. The circuit board comprises at least one electronic component on its first main surface. The circuit board of the electronic subassembly is arranged on the main circuit board by means of a press-fit connection and protrudes from the main circuit board at an angle of approximately 90 degrees. Furthermore, the invention relates to a method for producing an electronic assembly. State of the art

[0002] In automotive engineering, components such as transmission, engine, or braking systems are increasingly controlled primarily electronically. There is a trend toward integrated mechatronic control systems, i.e., the integration of control electronics and the associated electronic components such as sensors or valves into the transmission, engine, or braking system itself. This means that the control units are no longer located in a central, protected location, but directly on the respective component.

[0003] Transmission control units, in particular, generally contain numerous electronic components that are connected to other components outside the transmission control unit. Due to their location directly on the transmission, the control units are exposed to a multitude of external influences and must therefore be designed with exceptional robustness. In particular, the ingress of external fluids must be prevented to prevent damage to the control electronics. For this purpose, the control units' circuit boards are regularly overmolded to protect the individual components.

[0004] Depending on the topology of the individual circuit boards, very complex surface structures can arise. In addition to small electronic components with virtually no vertical extension, the complex requirements may also require components that protrude significantly from the main circuit board, partially forming freestanding structures. This type of topology results in highly jagged surfaces on the overmolded / overmolded circuit board. There is a particular risk that electronic components that protrude far from the circuit board will be damaged during the assembly process, for example, because they may bend, be incorrectly inserted into the injection or molding tools, or experience spatial collisions during production.

[0005] A particular disadvantage of the state-of-the-art devices and manufacturing processes for the known control units is that very complex circuit board topologies can only be overmolded or overmolded with great effort. There is a high risk of damage to the individual components, especially those that protrude from the circuit board like pins, during the processing.

[0006] From DE 10 2008 054 385 A1 an electrical circuit arrangement according to the preamble of patent claim 1 is known.

[0007] The KR 10 2019 0 087 565 A describes a printed circuit board and a corresponding method for producing the printed circuit board. Description of the invention, task, solution, advantages

[0008] Therefore, the object of the present invention is to create an electronic assembly that has an advantageous design and is therefore particularly easy to assemble and manufacture. Furthermore, the object of the invention is to create a method for producing such an electronic assembly.

[0009] The problem with regard to the electronic assembly is solved by an electronic assembly having the features of claim 1.

[0010] An embodiment of the invention relates to an electronic assembly with at least one main circuit board, with at least one electronic subassembly, wherein the electronic subassembly has at least one circuit board which has a first main surface and a second main surface which are arranged parallel to one another and lie opposite one another, wherein the circuit board has at least one electronic component on its first main surface, wherein the circuit board of the electronic subassembly is arranged on the main circuit board by means of a press-fit connection and protrudes from it at approximately a 90 degree angle, wherein a conducting element is arranged on the first main surface, which conducting element has a longer extension along a surface normal on the first main surface than the electronic component.

[0011] The main circuit board and the printed circuit board are preferably printed circuit boards (PCBs), as known in the art. An electronic component within the meaning of the invention is particularly preferably formed by a sensor that has been applied to the PCB using the surface mount device (SMD) technology known in the art. As an alternative to the sensor, other electronic components can also be provided. Particularly preferably, this is an electronic component that is sensitive to mechanical damage.

[0012] The main circuit board is preferably the base plate of a control unit, which is significantly larger than the circuit board of the electronic subassembly. A large number of electronic components are mounted on the main circuit board.

[0013] The electronic subassembly is attached to the main circuit board using a press-fit connection, known in the art. Contact pins are pressed through a metallized hole in the main circuit board, creating a press fit between the contact pins and the metallized hole. Over time, the positive connection partially or completely transforms into a material connection. The contact pins completely penetrate the main circuit board and protrude from the back of the main circuit board.

[0014] The electronic subassembly essentially protrudes at a right angle to the main circuit board, which is influenced by the mounting method. If multiple electronic subassemblies are arranged on the main circuit board, they can be distributed across the main circuit board and either aligned with the same surface area, so that the main surfaces of the electronic subassemblies are parallel to each other, or arranged at an angle to each other.

[0015] A conductive element is, in particular, a body that has no electrical function and is particularly robust. In particular, the conductive element is designed to be so robust that contact with the wall of a mold or molding tool does not cause damage to the conductive element. It is preferably a metallic body, which is also applied to the circuit board automatically using SMD technology. This is particularly advantageous for enabling fully automated production of electronic subassemblies.

[0016] The electronic subassembly serves to create so-called sensor domes, which protrude finger-like from the main circuit board, thus enabling values ​​to be recorded at locations within the mechanical component to be controlled by the electronic assembly according to the invention. In particular, the sensors are intended to detect the movements of shafts and gears, but also rotational speeds, rotational speeds, and other relevant values. With regard to a sensor intended to detect the rotational speed of a shaft inside a gearbox, it is advantageous if this sensor can be mounted as close to the shaft as possible without having to be installed as a fragile individual component in the gearbox.Therefore, the aim is to design the sensor as a unit with the main circuit board, to protect the main circuit board and electronic subassembly together against mechanical damage by overmolding and yet to ensure that the sensor is used at a location remote from the main circuit board.

[0017] The guide element serves in particular to protect this sensor and is therefore designed in such a way that it extends further from the main surface of the circuit board than the sensor itself. This is intended to prevent the sensor from being damaged when it is inserted into a mold, as the guide element is intended to come into contact with the inner walls of the mold before the sensor. Contact between the guide element and the inner wall of the mold can cause the circuit board to tilt relative to the main circuit board, which improves the alignment of the circuit board with the mold and allows it to be inserted into the mold without damage. The circuit board therefore slides over the guide element on the inner wall of the mold and there is no force transmission to the sensor itself, which both protects the sensor from damage and protects the electrical connection between the sensor and the conductor tracks of the circuit board from damage.

[0018] According to the invention, it is provided that the guide element is arc-shaped, wherein the two foot regions are arranged on the circuit board and the maximum of the arc-shaped guide element forms the point of the guide element furthest away from the circuit board.

[0019] The conducting element is in particular shaped like a sine wave with the wave minimum in the two foot regions that sit on the circuit board and are connected to it there. The wave maximum is the region furthest away from the circuit board and generally represents the area where the main contact between the conducting element and one of the inner walls of the mold takes place. The conducting element is preferably oriented such that the two foot regions are arranged one above the other on the circuit board, so that one of the foot regions is arranged closer to the main circuit board than the other. In a particularly preferred embodiment, the foot regions are arranged in a line that runs parallel to the outer edge of the circuit board, which is perpendicular to the main circuit board.

[0020] It is also advantageous if the conductive element is applied to the circuit board using SMD technology. Using SMD technology is advantageous because it allows the conductive element to be applied to the circuit board in a highly automated manner, allowing the entire electronic subassembly to be produced with a high degree of automation, making manufacturing simpler and more cost-effective.

[0021] A preferred embodiment is characterized in that the main circuit board and the circuit board are overmolded and / or overmolded, wherein the sections of the press-fit connectors that protrude through the main circuit board are also completely overmolded and / or overmolded.

[0022] The electronic assembly, formed from the main circuit board and one or more of the electronic subassemblies, is advantageously inserted into a mold and, after precise positioning in the mold, overmolded with a thermoset. This occurs under working pressures of approximately 60 to 70 bar and at temperatures of up to 180 degrees Celsius. It is essential that all electronic components arranged on the main circuit board, as well as the entire electronic subcomponent, are overmolded with the thermoset to ensure that none of the overmolded elements protrude from the thermoset, which could cause mechanical damage or fluid ingress. After overmolding, the electronic subassemblies protruding from the main circuit board form finger-like structures that protrude from the main circuit board and are colloquially called sensor domes.

[0023] According to the invention, the underside of the main circuit board is also overmolded with the thermoset. Particularly preferably, at least the contact pins protruding through the main circuit board are overmolded with the thermoset to prevent damage or unwanted electrical contact.

[0024] It is also preferable if the electronic subassembly can be pivoted around the press-fit connection by a range of up to 3.5 degrees in the direction of the first main surface and the second main surface. The press-fit connection, which is preferably formed by three contact pins, allows a relative movement of the circuit board to the main circuit board by a pivot angle of plus or minus 3.5 degrees. This simplifies the assembly of the electronic subassemblies, as a suitable mold shape enables precise positioning of the electronic subassembly.

[0025] Furthermore, it is advantageous if the main circuit board has a plurality of electronic subassemblies, all of which protrude from the same surface of the main circuit board. Depending on the application, a plurality of electronic subassemblies can be provided, each fulfilling different functions. The electronic subassemblies preferably have sensors for detecting rotational speeds, rotational velocities, and relative movements. The electronic subassemblies are preferably distributed across the main circuit board in such a way that the sensor domes created by overmolding the electronic subassemblies can be inserted directly into corresponding openings on the mechanical component to be controlled.

[0026] Furthermore, it is advantageous if the electronic component on the second main surface is arranged closer to the lateral end region of the circuit board than the conductive element, relative to the press-fit connection with the main circuit board. This is advantageous to ensure that the conductive element comes into mechanical contact with the inner walls of the mold before the sensor when inserted into the mold, thus protecting the sensor from damage. Furthermore, it is advantageous if the sensor is located at the tip of the formed sensor dome to ensure optimal placement in the mechanical component to be controlled.

[0027] The problem with regard to the method is solved by a method having the features of claim 7.

[0028] An embodiment of the invention relates to a method for producing an electronic assembly according to one of the preceding claims, wherein the main circuit board is equipped with at least one electronic subassembly using a press-fit method, wherein the electronic assembly with the at least one electronic subassembly protruding from it is inserted into the molding tool, wherein the molding tool for the at least one electronic subassembly has a pocket that tapers with the insertion depth for receiving the at least one electronic subassembly, wherein the at least one electronic subassembly is guided into the pocket either by the second main surface sliding on a first inner wall of the pocket or by the guide element sliding on the second inner wall of the pocket, which is opposite the first inner wall, during insertion into the pocket.

[0029] The mold is formed from a negative mold of the finished control unit. It has a receptacle for the main circuit board and the sensor domes protruding from the main circuit board. The entire electronic assembly is overmolded with the thermoset, thus forming a dimensionally stable unit. Suitable interfaces penetrating the thermoset allow contact to be made between the electronic assembly's conductor tracks, allowing the control unit to be integrated into the vehicle's peripherals.

[0030] The pockets for accommodating the electronic subassemblies taper along the insertion direction, so that the subsequent foot area of ​​the sensor domes is wider and more stable than the tip of the sensor domes, in which the respective sensors are also arranged.

[0031] Due to the press-fit connections, the electronic subassemblies exhibit a certain degree of mobility relative to the main circuit board. Therefore, it may happen that the electronic subassemblies are not aligned at the correct angle to the main circuit board required for overmolding. This phenomenon is counteracted by allowing the second main surface and / or the conductive element to slide along the opposing inner walls of the respective pocket. Alignment of the electronic subassemblies is achieved by tapering the pocket with increasing insertion depth.

[0032] It is also expedient if the first inner wall of the pocket has an insertion bevel in the upper end region of the pocket, which has an inclination which differs from the remaining inner wall, wherein the second main surface slides past the insertion bevel when the electronic subassembly is inserted and the electronic subassembly is positioned in its final position between the two inner walls.

[0033] The insertion bevel is advantageous for achieving the final positioning of the electronic subassembly. The insertion bevel preferably has a greater inclination than the inner wall on which the insertion bevel is formed. The insertion bevel guides the second main surface away from the inner wall, thus positioning the circuit board at a 90-degree angle to the main circuit board as precisely as possible.

[0034] Preferably, the lead-in chamfer created by an inwardly directed molding has a smaller width than the circuit board, with the width of the circuit board being measured transversely to the main surface. This results in the circuit board being completely overmolded by the thermoset over part of its width. The area of ​​the second main surface, which in the final position rests against the lead-in chamfer, may not be completely overmolded by the thermoset or may only be overmolded over a very thin area.

[0035] Furthermore, it is advantageous if the electronic subassembly and the electronic assembly are overmolded or overmolded with a thermosetting plastic in the molding tool after the electronic subassembly has reached its final position in the pocket.

[0036] Furthermore, it is expedient if the electronic component arranged on the second main surface is spaced apart from the inner walls of the pocket in the final position after completion of insertion into the mold. This is advantageous to ensure that the electronic component is completely overmolded by the thermoset and thus protects the component from external influences. For this purpose, the guide element is dimensioned such that, upon reaching the final position in the mold, an air gap sufficient for full-surface overmold formation is formed between the electronic component and the inner wall.

[0037] Furthermore, it is advantageous if the electronic subassembly, in its final position after insertion into the mold, rests with its second main surface against the insertion bevel and with its guide element against the second inner wall of the pocket. The contact of the two areas against the opposite inner walls is advantageous to ensure that the electronic subassembly is correctly aligned in the mold and that a flawless overmolding process can be carried out.

[0038] Advantageous further developments of the present invention are described in the subclaims and in the following description of the figures. Short description of the drawings

[0039] The invention is explained in detail below using exemplary embodiments with reference to the drawings. In the drawings: Fig. 1 a plan view of the electronic subassembly, showing the first main surface with the electronic component, the guide element and the press-fit connecting elements, Fig. 2 a side view of the electronic subassembly, Fig. 3 a side view of the electronic subassembly in overmolded condition, Fig. 4 a sectional view through the molding tool, wherein the electronic subassembly is inserted into the molding tool from above and the guide element rests against the molding tool, Fig. 5 a sectional view through the molding tool, wherein the electronic subassembly is inserted into the molding tool from above and the second main surface rests against the molding tool, Fig. 6 a sectional view through the molding tool, wherein the electronic subassembly is inserted into the molding tool from above and rests on one side with the second main surface on the molding tool and the guide element also rests on the inner surface of the molding tool, and Fig. Figure 7 shows a view of the molding tool, showing in particular the tip of the pocket into which the circuit board is inserted. Preferred embodiment of the invention

[0040] The Fig. Figure 1 shows a view of a printed circuit board 1 with an electronic component 2, for example, a sensor. A conductive element 3 is also shown on the printed circuit board 1. At the base of the printed circuit board 1, three press-fit connectors 4 are shown, with which the printed circuit board 1 is connected to the main printed circuit board 5. The printed circuit board 1 and the main printed circuit board 5 are preferably formed by printed circuit boards (PCBs). The electronic component 2 and the conductive element 3 are applied to the printed circuit board 1 using surface-mounted device (SMD) technology.

[0041] Fig. 2 shows a side view of the circuit board 1 from Fig. 1. It can be seen that the printed circuit board 1 has an electronic component 2, a conductive element 3, and the press-fit connectors 4 on the first main surface 6. The second main surface 7, which is opposite the first main surface 6, is not equipped with electronic components.

[0042] Fig. 3 shows the circuit board 1 of the Fig. 2, wherein the circuit board 1 is injected into a thermoset 8. The thermoset 8 completely encloses the electronic component 2, the conductive element 3 and the press-fit connectors 4. As in Fig. 3, the underside of the main circuit board 5 is also covered with the thermosetting plastic 8, so that the ends of the press-fit connectors 4 protruding through the main circuit board 5 are also completely enclosed.

[0043] Fig. Figure 4 shows the circuit board 1 upside down as it is inserted into the molding tool 9 along the insertion direction 11. It can be seen that the circuit board 1 rests with the conductive element 3 against the contact point 10 of the inner wall of the mold, while the electronic component 2 is spaced from the inner wall. The circuit board 1 does not protrude at an exact 90-degree angle from the main circuit board 5, which is why the circuit board 1 comes into contact with the inner wall.

[0044] The main circuit board 5 is positioned precisely over the molding tool 9 using an automated process. If the circuit board 1 were positioned at exactly 90 degrees on the main circuit board 5, the circuit board 1 could be pushed precisely into the recess in the molding tool 9. Due to the slightly different angle, a collision with the molding tool 9 occurs when the circuit board 1 is pushed in. Contact with the guide element 3 straightens the circuit board 1 and allows it to be guided precisely into the mold.

[0045] Fig. 5 shows the circuit board 1 as shown in Fig. 4 was shown, over the mold tool 9. In Fig. 5, the circuit board 1 is deflected in the opposite direction from the 90-degree angle, which is why the second main surface of the circuit board 1 rests against the inner wall of the mold at the contact point 12. By inserting the circuit board 1 along the insertion direction 11, the second main surface slides along the inner wall and finally over the insertion bevel 13 into the final position, in which the circuit board 1 is finally overmolded in the molding tool 9.

[0046] Fig. Figure 6 shows the printed circuit board 1 in its final position in the molding tool 9. In the final position, the second main surface rests against the insertion bevel 13, while the guide element 3 rests against the opposite inner wall. In the final position, the printed circuit board 1 protrudes almost exactly at a 90-degree angle from the main printed circuit board 5. The electronic component 2 is arranged completely spaced from the inner walls of the molding tool 9, so that it can be completely overmolded.

[0047] Fig. 7 shows the tip of the molding tool 9 in the upper area. The reference number 14 indicates the insertion bevel, which helps to guide the printed circuit board 1 into its correct final position. The insertion bevel 14 is only formed over approximately 1 / 3 of the width of the pocket of the molding tool 9. This means that 2 / 3 of the width of the pocket is formed without the insertion bevel 14 and thus the second main surface is not in complete contact with the inner wall in the final position and thus cannot be overmolded with the thermoset in this non-contacting area. This results in only a very small area on the second main surface of the printed circuit board 1 that cannot be completely overmolded with the thermoset or can only be overmolded over a very thin area.

[0048] In the lower part of the Fig. 7 shows a section through the molding tool 9, wherein the circuit board 1 is completely inserted into the molding tool 9.

[0049] The examples of the Fig. 1 to 7 are not restrictive in nature and serve to clarify the inventive concept. List of reference symbols 1 circuit board 2 Electronic components 3 Guide element 4 press-fit connectors 5 Main circuit board 6 first main area 7 second main area 8 Duroplast 9 mold tool 10 Contact point 11 Insertion direction 12 Contact point 13 insertion bevel 14 insertion bevel

Claims

[1] Electronic assembly with at least one main circuit board (5), with at least one electronic subassembly, wherein the electronic subassembly has at least one circuit board (1) which has a first main surface (6) and a second main surface (7) which are arranged parallel to one another and opposite one another, wherein the circuit board (1) has at least one electronic component (2) on its first main surface (6), wherein the circuit board (1) of the electronic subassembly is arranged on the main circuit board (5) by means of a press-fit connection (4) and protrudes from it at an angle of approximately 90 degrees, wherein a guide element (3) is arranged on the first main surface (6), which guide element has a longer extension along a surface normal on the first main surface (6) than the electronic component (2), characterized bythat the guide element (3) is arc-shaped, wherein the two foot regions are arranged on the printed circuit board (1) and the maximum of the arc-shaped guide element (3) forms the point of the guide element (3) furthest away from the printed circuit board (1). [2] Electronic assembly according to claim 1, characterized by that the conductive element (3) is applied to the circuit board (1) using SMD technology. [3] Electronic assembly according to one of the preceding claims, characterized by that the main circuit board (5) and the circuit board (1) are overmolded and / or overmolded, wherein the sections of the press-fit connection (4) projecting through the main circuit board (5) are also completely overmolded and / or overmolded. [4] Electronic assembly according to one of the preceding claims, characterized bythat the electronic subassembly can be pivoted about the press-fit connection (4) by a range of up to 3.5 degrees in the direction of the first main surface (6) and the second main surface (7). [5] Electronic assembly according to one of the preceding claims, characterized by that the main circuit board (5) has a plurality of electronic subassemblies, which all protrude from the same surface of the main circuit board (5). [6] Electronic assembly according to one of the preceding claims, characterized by that the electronic component (2) on the second main surface (7) is arranged closer to the lateral end region of the circuit board (1) than the conducting element (3) relative to the press-fit connection (4) with the main circuit board (5). [7] Method for producing an electronic assembly according to one of the preceding claims, wherein the main circuit board (5) is equipped with at least one electronic subassembly using the press-fit method, wherein the electronic assembly with the at least one electronic subassembly projecting from it is inserted into the molding tool (9), wherein the molding tool (9) for the at least one electronic subassembly has a pocket tapering with the insertion depth for receiving the at least one electronic subassembly, characterized by that the at least one electronic subassembly is guided during insertion into the pocket either by the second main surface (7) sliding along a first inner wall of the pocket or by the guide element (3) sliding along the second inner wall of the pocket, which is opposite the first inner wall. [8] Method for producing an electronic assembly according to claim 7, characterized byin that the first inner wall of the pocket has an insertion bevel (13, 14) in the upper end region of the pocket, which has an inclination which differs from the remaining inner wall, wherein the second main surface (7) slides past the insertion bevel (13, 14) when the electronics subassembly is pushed in, and the electronics subassembly is positioned in its final position between the two inner walls. [9] Method for producing an electronic assembly according to claim 7 or 8, characterized by that the electronic subassembly and the electronic assembly are overmolded or overmolded with a thermosetting plastic (8) in the molding tool (9) after the electronic subassembly has reached its final position in the pocket. [10] Method for producing an electronic assembly according to one of claims 7 to 9, characterized bythat the electronic component arranged on the second main surface (7) is arranged at a distance from the inner walls of the pocket in the final position after completion of the insertion into the molding tool (9). [11] Method for producing an electronic assembly according to one of claims 7 to 10, characterized by that the electronic subassembly in the final position after completion of the insertion into the molding tool (9) rests with the second main surface (7) on the insertion bevel (13, 14) and rests with the guide element (3) on the second inner wall of the pocket.

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