Partially overmolded electronic component with lost seal, method for manufacturing an electronic component, use of the electronic component, and motor vehicle

Abstract

The invention relates to an electronic component (EC) for a motor vehicle (MV), comprising a printed circuit board (PCB) with a top surface (SSP), wherein an electrically conductive guide element (LE) is arranged on and / or in the top surface (SSP), a frame element (RE) is placed on the top surface (SSP), which is recessed in the area of ​​the guide element (LE), and seals against the guide element (LE) via a sealing element (DE), wherein the sealing element (DE) has a lower stiffness than the frame element (RE), and the top surface (SSP) and the frame element (RE) are partially encapsulated and / or overmolded with an overmold material (OMM).

Description

[0001] The invention relates to a partially overmolded electronic component comprising a printed circuit board (PCB), wherein the PCB has a top surface on which an electrically conductive element is arranged. During the partial overmolding process, this conductive element is protected from mechanical impacts by a sealing element arranged in a frame. The invention also relates to a method for manufacturing the electronic component. Furthermore, the invention relates to the use of the electronic component in an inverter or a transmission control unit. Finally, the invention relates to a motor vehicle incorporating the electronic component according to the invention.

[0002] Overmolded electronic components are generally known. These components typically consist of a printed circuit board (PCB). A problem with these components is that when a tool is moved onto the PCB for partial overmolding, the conductive traces on the PCB can be damaged in the sealing area. This leads to increased scrap and therefore higher production costs.

[0003] From DE 10 2012 213 917 A1, a component encapsulation for an electronic module is known, in which a frame acts directly against a preferably structured conductor track of a printed circuit board.

[0004] DE 44 05 710 A1 shows a device with a carrier plate in which a frame is mounted on a printed circuit board, wherein the frame is designed to be recessed in the area of ​​an electronic component embedded in the printed circuit board.

[0005] The object of the invention is to provide a partially overmolded electronic component with conductive elements in the edge area of ​​an overmolding, which is easy and inexpensive to manufacture.

[0006] The problem is solved by the subject matter of the independent patent claims. Preferred embodiments of the invention are the subject matter of the dependent patent claims, the following description, and / or the drawings. Each disclosed feature, either individually or in combination, can represent an aspect of the invention, unless explicitly stated otherwise in the description.

[0007] In a first aspect, the invention relates to an electronic component for a motor vehicle, comprising a printed circuit board with a top surface, wherein an electrically conductive guide element is arranged on and / or in the top surface, a frame element is placed on the top surface which is recessed in the area of ​​the guide element and seals against the guide element via a sealing element, the sealing element having a lower stiffness than the frame element, and the top surface and the frame element are sectionally encapsulated and / or overmolded with an overmold material, wherein a sealing element receptacle is formed in the frame element, and the sealing element receptacle is configured and / or designed to receive and hold the sealing element, so that when the frame element is pressed onto the top surface of the printed circuit board, the sealing element seals against the guide element.

[0008] In other words, according to the first aspect of the invention, an electronic component is provided for a motor vehicle. The electronic component is preferably arranged in a transmission control unit or in an inverter of a motor vehicle. According to the invention, the electronic component comprises a printed circuit board (PCB). It is conceivable that the PCB is preferably designed as a multilayer PCB. The PCB has a top surface, wherein an electrically conductive element is arranged on and / or in the top surface. If the PCB is preferably designed as a flat or planar PCB, the top surface is parallel to the plane of the PCB.

[0009] Regarding the arrangement of the guide element on and / or in the top surface, "on the top surface" means that the guide element protrudes or extends beyond the top surface, and "in the top surface" means that the guide element is flush with the top surface.

[0010] A frame element is mounted on the top surface, recessed in the area of ​​the conductive element. In other words, the frame element rests on the top surface. The contact can be direct. In the area of ​​the electrical conductive element, the frame element itself does not have direct contact with the conductive element. The conductive element seals against the frame element indirectly via a sealing element. The sealing element has a lower stiffness than the frame element. In other words, the material stiffness of the frame element is higher than the stiffness of the sealing element. The top surface of the conductor plate and the frame element are partially encapsulated and / or overmolded with an overmold material. The frame element thus acts as a barrier for the overmold material. The overmold material preferably protects the top surface in the overmolded area from aggressive media.Furthermore, the frame element can be fixed to the circuit board by overmolding it section by section. Because the rigidity of the sealing element is reduced compared to the frame element, damage to the guide element during the overmolding process, in which the frame element is also pressed against the circuit board, can be prevented. This reduces the number of circuit board rejects during the production of the electronic component, which can have a positive impact on manufacturing costs.

[0011] According to the invention, a sealing element receptacle is formed in the frame element. The sealing element receptacle is designed and / or configured to receive and hold the sealing element so that, when the frame element is pressed onto the top surface of the printed circuit board, the sealing element seals against the conductor element. In this way, the frame element, together with the sealing element arranged in the sealing element receptacle, can be easily placed onto the top surface of the printed circuit board, thereby reducing the manufacturing costs of the electronic component.

[0012] The sealing element is preferably a seal made of a fluoroelastomer compound (FKM). In other words, the sealing element preferably comprises a fluoroelastomer. Sealing elements made of a fluoroelastomer exhibit increased heat resistance and increased resistance to a wide variety of chemicals. Thus, an FKM sealing element is particularly suitable for use against harsh media, such as oils, and is especially applicable in the automotive sector, where high temperatures are sometimes reached by electronic components. The sealing element preferably, but not exclusively, has a Shore hardness between 55 Shore A and 85 Shore A, more preferably between 60 Shore A and 83 Shore A, and most preferably between 70 Shore A and 80 Shore A, including the limits of this range.

[0013] The overmold material preferably comprises a plastic. The plastic is particularly preferably a thermosetting plastic. Most preferably, the plastic includes an additive. The additive or matrix can increase the stiffness of the overmold material in its cured state. Furthermore, the additive can increase the tensile strength of the overmold material, which can be advantageous in the presence of increased temperature fluctuations to prevent cracking of the overmolding or the overmold material itself. In other words, this allows for a simple and cost-effective increase in the media tightness of the overmold material. The additive can preferably comprise glass fiber and / or carbon fiber.

[0014] An advantageous embodiment of the invention lies in the fact that the conductive element is an electrically conductive conductor track or conductive foil. The conductor track or foil can preferably be made of copper and / or contain copper. With a conductor track or foil, an increased functional density can be achieved for the electrical control of the transmission control unit or an inverter. This increased functional density can have a beneficial effect on the cost of the electronic component and also on the installation space required.

[0015] It is conceivable that the conductor track is at least partially uncoated. In other words, no solder mask is applied to the conductor track or conductive film, particularly in the overmolded area. Such conductor tracks must therefore be specially protected during a partial overmolding process where an edge of the overmolding extends into the area of ​​the conductor track or conductive film, to prevent damage to the conductor track or conductive film during the overmolding process when a sealing tool is applied to the top surface of the printed circuit board.

[0016] In a preferred embodiment of the invention, the guiding element is an electrical component. The electrical component can preferably be a transistor, in particular a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT), or a connector. The frame element therefore does not rest directly on the electrical component, but rather seals against it via the sealing element. Thus, the electrical component can be protected from damage during partial overmolding, where the electrical component also falls within the edge region of the overmolding.

[0017] According to a preferred embodiment of the invention, the frame element is at least partially bonded to the top surface. It is conceivable that the frame element has an adhesive layer on one side facing the top surface, which is preferably activated during the overmolding process and particularly preferably by the application of heat, thus forming a bonded connection with the top surface. In this way, the tightness between the frame element and the top surface of the printed circuit board can be increased, which can have a beneficial effect on the media tightness of the overmolded area of ​​the printed circuit board.

[0018] In principle, the frame element can be made of a metallic material. A preferred embodiment of the invention is that the frame element is made of a plastic and / or at least partially comprises plastic. The plastic is preferably a thermoplastic. The thermoplastic can be, but is not limited to, a polyamide. A frame element made of and / or comprising plastic can be manufactured inexpensively and easily. Furthermore, with a frame element made of a plastic, particularly a thermoplastic, a material-bonded connection to the top surface of the printed circuit board can be achieved by applying heat to the frame element during the overmolding process, thus eliminating the need for an adhesive layer.This allows for a simple and cost-effective way to achieve increased media tightness between the top surface and the frame element.

[0019] In this context, a preferred embodiment of the invention lies in the fact that the sealing element can be inserted and / or is inserted into the sealing element receptacle starting from an outer surface of the frame element facing away from the top surface. In other words, the sealing element receptacle is provided to be an opening and / or recess extending through the frame element, preferably with closed edges. The opening and / or recess preferably has a converging and / or tapered design, extending from the outer surface of the frame element towards the top surface of the circuit board. The sealing element can preferably be inserted into the sealing element receptacle in a simple manner, starting from the outer surface of the frame element. During the overmolding process, a plunger can act on the sealing element arranged in the sealing element receptacle and press it against the electrically conductive guide element.In this way, a safe and gentle sealing of the sealing element to the guide element can be achieved during the overmolding process.

[0020] A preferred embodiment of the invention consists in the sealing element being at least partially encased in the overmold material. In particular, it is provided that the sealing element is at least partially encased in the sealing element receptacle with the overmold material. Particularly preferred is the sealing element being encased in the sealing element receptacle of the frame element, at least partially, starting from the outside of the frame element. By encased the sealing element in sections, especially within the sealing element receptacle, the sealing element can be securely and permanently fixed in the receptacle. This increases the media tightness in the sealing area between the electrical conductor and the sealing element.

[0021] In an advantageous embodiment of the invention, a recess is formed in a wall of the sealing element receptacle, wherein the wall faces a section and / or area of ​​the printed circuit board encapsulated with overmold material. This recess is also encapsulated with overmold material. During the overmolding process, the overmold material can flow through the recess onto the sealing element and at least partially enclose it within the sealing element receptacle, thus ensuring that the sealing element is securely and permanently fixed in the sealing element receptacle of the frame element.

[0022] In a second aspect, the invention relates to a method for manufacturing the electronic component according to the invention, comprising the following steps: - Providing a printed circuit board having a top surface, wherein an electrically conductive conductor is arranged on and / or in the top surface, - Arranging a frame element on the top side, which is recessed in the area of ​​the guide element, wherein a sealing element is arranged in the frame element in the area of ​​the guide element, the sealing element having a lower stiffness than the frame element, - Pressing the frame element against and / or onto the top of the circuit board and the sealing element against and / or onto the guide element, - Overmolding and / or casting of the top surface, at least in sections, with an overmold material.

[0023] In other words, according to the second aspect of the invention, a method for manufacturing the electronic component according to the invention is provided, in which the frame element is placed on the top side of the printed circuit board. The sealing element is arranged within the frame element. The sealing element has a reduced stiffness compared to the frame element. For the partial overmolding of the top side of the printed circuit board with an overmold material, the frame element is pressed against the top side, and the sealing element seals against the electrically conductive conductor element of the printed circuit board. Thus, the frame element acts as a boundary for overmolding the top side of the printed circuit board with the overmold material. The sealing element in the frame element prevents damage to the conductor element in the sealing area in a simple and cost-effective manner.

[0024] In a preferred embodiment of the invention, the steps of pressing the frame element against and / or onto the top surface and the partial overmolding of the top surface of the printed circuit board with an overmold material are performed simultaneously. "Simultaneously" means that while the frame element is being pressed against the top surface, the top surface is being partially overmolded. The pressing process preferably lasts somewhat longer than the overmolding process. It is conceivable, therefore, that a pressing force is applied to the frame element to press it against the top surface. The overmolding process then begins. The overmolding process ends, and the pressing force on the frame element is reduced or removed after or at the end of the overmolding process. By pressing the frame element against the top surface beforehand, it is possible to prevent the overmold material from escaping between the frame element and the top surface at the start of the overmolding process.If the clamping force is relieved or removed after the overmolding process is complete, it can be ensured that the overmold material cures before the clamping pressure on the frame element, and thus on the top surface of the printed circuit board, is reduced. However, it is also conceivable, and not excluded, that the overmolding process begins and ends immediately with the clamping process. In this case, the clamping and overmolding processes are not only simultaneous but also concurrent, as they have the same duration. This can reduce the cycle time for manufacturing the electronic component, which can have a positive impact on production costs.

[0025] An advantageous embodiment of the invention lies in the fact that, during the overmolding step of the top surface of the printed circuit board, a temperature greater than 80°C, particularly greater than 100°C, is applied to the top surface of the printed circuit board and / or the frame element, thereby achieving a metallurgical bond between the frame element and the top surface. The temperature is preferably not greater than 150°C and particularly preferably not greater than 130°C. The metallurgical bond can preferably be achieved via a thermally activated adhesive layer between the frame element and the top surface of the printed circuit board. It is also conceivable that the frame element is made of a plastic, wherein the frame element softens section by section due to the heat input and thus forms a metallurgical bond with the top surface of the printed circuit board. The metallurgical bond can increase the media tightness between the printed circuit board and the frame element.

[0026] In a preferred embodiment of the invention, it is provided that during the step of partially overmolding the top surface of the printed circuit board, the sealing element is also at least partially encapsulated in a sealing element receptacle formed in the frame element. In particular, it is provided that the sealing element is encapsulated on a side facing away from the top surface within the sealing element receptacle. By encapsulating the sealing element within the sealing element receptacle, it can be securely fixed in position and irretrievably arranged within the receptacle, thus ensuring a permanent media tightness to the guide element via the sealing element.

[0027] In a third aspect, the invention relates to the use of the electronic component according to the invention in a transmission control unit or in an inverter for a motor vehicle.

[0028] In other words, the electronic component is intended to be installed in a transmission control unit of a motor vehicle. The transmission control unit is preferably at least partially surrounded by oil, in particular transmission oil. The oil can preferably counteract overmolding. It is also conceivable that the electronic component is arranged in an inverter of a traction drive of a motor vehicle. The inverter can preferably be cooled. The cooling of the inverter can be oil cooling or water-glycol cooling, which preferably counteracts overmolding of the electronic component.

[0029] In a fourth aspect, the invention relates to a motor vehicle with the electronic component according to the invention.

[0030] It should be noted that all features described above and below with respect to one aspect of the present invention apply equally to every other aspect of the present invention. In particular, all features of the electronic component can apply equally to the method for manufacturing the electronic component, to the use of the electronic component in a transmission control unit or an inverter, and / or to the motor vehicle. The reverse is also true.

[0031] Further features and advantages of the present invention will become apparent from the dependent claims and the following exemplary embodiments. These exemplary embodiments are not intended to be limiting, but rather to be understood as illustrative examples. They are meant to enable a person skilled in the art to carry out the invention. The applicant reserves the right to make one or more of the features disclosed in the exemplary embodiments the subject of patent claims, or to include such features in existing patent claims. The exemplary embodiments are explained in more detail with reference to the drawings.

[0032] These show: Fig. 1 a section of an electronic component with a circuit board and frame element, Fig. 2 a section of the electronic module with the circuit board, the frame element and an inserted sealing element, Fig. 3 a section of the electronics module with the circuit board, the frame element and a partial potting of the circuit board, Fig. 4 a section through the electronic module in the area of ​​an electrically conductive conductor element of the circuit board, Fig. 5 a method for manufacturing the electronic module, Fig. 6 a motor vehicle with the electronic module.

[0033] In the Fig. 1, Fig. 2 and Fig. Figure 3 shows a section of an electronic component EB. The following refers to the... Fig. References 1 to 3 are made simultaneously. The electronic component EB comprises a printed circuit board (PCB) LP. The PCB LP can preferably be designed as a multilayer PCB. The PCB LP has a top surface OS, wherein an electrically conductive conductor element LE is arranged on and / or in the top surface OS. The top surface OS is parallel to the plane of the PCB LP if the PCB LP is designed as a flat or planar PCB LP. Arranged on the top surface OS means that the conductor element LE projects from the top surface OS. In the top surface OS means that the conductor element LE is flush with the top surface OS. In the present embodiment, the conductor element LE is an electrically conductive conductor track. The conductor track can preferably be made of copper and / or have copper components. A conductor track allows for increased functional density for electrical control.The increased functional density can have a beneficial effect not only on the cost of the electronic component EB, but also on the installation space required for the electronic component EB.

[0034] A frame element RE is mounted on the upper surface OS. The frame element RE is recessed in the area of ​​the conductive element LE. In other words, the frame element RE rests on the upper surface OS. In the present embodiment, it rests directly on the upper surface OS. In the area of ​​the electrically conductive conductive element LE, the frame element RE itself has no direct contact with the conductive element LE.

[0035] Furthermore, it is provided that a sealing element receptacle DEA is formed in the frame element RE. The sealing element receptacle DEA is designed and / or configured to receive and hold a sealing element DE, as shown in Fig. 2 can be seen, so that when the frame element RE is pressed onto the top surface OS of the circuit board LP, the sealing element DE seals against the conductor element LE.

[0036] The sealing element receptacle DEA is an opening and / or recess extending through the frame element RE, preferably with closed edges. This allows the sealing element DE to be inserted into the sealing element receptacle DEA from an outer surface AS of the frame element RE facing away from the top surface OS.

[0037] The opening and / or recess of the sealing element receptacle DEA has a converging and / or tapered design, extending from the outer surface AS of the frame element RE towards the top surface OS of the printed circuit board LP. The sealing element DE can preferably be inserted into the sealing element receptacle DEA in a simple manner, starting from the outer surface AS of the frame element RE, and seal against an inclined inner wall of the sealing element receptacle DEA, thereby increasing the media tightness of the sealing element DE to the frame element RE.

[0038] The guide element LE seals against the frame element RE indirectly via the sealing element DE. The sealing element DE has a lower stiffness than the frame element RE. In other words, the material stiffness of the frame element RE is higher than the stiffness of the sealing element DE.

[0039] The sealing element DE is preferably an elastomer and the frame element RE is particularly preferably made of a thermoplastic material.

[0040] The top surface of the conductor plate LP and the frame element RE are sectionally cast and / or overmolded with an overmold material OMM, as described in Fig. As can be seen in Figure 3, the frame element RE thus acts as a barrier for the overmold material OMM. The overmold material OMM protects the top surface OS and / or the electrical components located on the top surface OS (not shown) from aggressive media in the overmolded area. Furthermore, the sectional overmolding of the frame element RE simultaneously fixes the frame element RE to the printed circuit board LP. Because the stiffness of the sealing element DE is reduced compared to the frame element RE, damage to the guide element RE during the overmolding process, in which the frame element RE is also pressed against the printed circuit board LP, can be avoided. This reduces scrap in the production of the printed circuit boards LP, which can have a beneficial effect on the manufacturing costs of the electronic component EB.

[0041] Furthermore, it is evident that a recess VT is formed in a wall of the sealing element receptacle DEA, the wall of which faces a section and / or area of ​​the printed circuit board LP encapsulated with the overmold material OMM. This recess is also encapsulated with the overmold material OMM. During the overmolding process, the overmold material OMM can flow through the recess onto the sealing element DE and at least partially enclose it within the sealing element receptacle DEA, thus ensuring that the sealing element DE is securely and permanently fixed within the sealing element receptacle DEA of the frame element RE.

[0042] Fig. 4 shows a section AA through the in Fig. 3. Electronic component EB is shown. It is evident that the frame element RE rests on the top surface OS of the printed circuit board LP and has no direct contact with the conductive element LE. The sealing element DE, located in the frame element RE, seals against the conductive element LE. The sealing element DE is at least partially encapsulated in the sealing element receptacle DEA with the overmold material OMM and is thus securely fixed in position within the sealing element receptacle DEA.

[0043] Fig. Figure 5 shows a method for manufacturing the electronic component EB.

[0044] In a first step, the printed circuit board (PCB) LP is provided. The PCB LP has the top surface OS, on and / or in the top surface OS the electrically conductive element LE is arranged.

[0045] In a second step 110, a frame element RE is arranged on the top surface OS of the printed circuit board LP, wherein the frame element RE has a sealing element DE in the area of ​​the guide element LE, and the sealing element DE has a lower stiffness compared to the frame element RE.

[0046] In a third step 120, the frame element RE is pressed against the top surface OS of the printed circuit board LP, and the sealing element acts and seals against the conductive element.

[0047] In a fourth step 130, the top surface OS of the printed circuit board LP is overmolded at least partially or in sections with an overmold material OMM.

[0048] The frame element RE acts as a boundary for overmolding the top surface OS of the printed circuit board LP with the overmold material OMM. The sealing element DE within the frame element RE provides a simple and cost-effective way to prevent damage to the conductive element LE in the sealing area, as the mechanical stresses on the conductive element LE during the pressing process of the frame element RE onto the top surface OS of the printed circuit board LP are significantly reduced.

[0049] Fig. Figure 6 shows a motor vehicle (KFZ) with the electronic component EB. The electronic component EB is preferably integrated into a transmission control unit (GSG).

Claims

[1] Electronic component (EB) for a motor vehicle (KFZ), comprising a printed circuit board (LP) with a top side (OS), wherein an electrically conductive guide element (LE) is arranged on and / or in the upper side (OS), on the upper side (OS) a frame element (RE) is placed, which is designed to be recessed in the area of the guide element (LE) and seals against the guide element (LE) via a sealing element (DE), wherein the sealing element (DE) has a lower rigidity than the frame element (RE), and the top side (OS) and the frame element (RE) are cast and / or overmolded in sections with an overmold material (OMM), wherein a sealing element receptacle (DEA) is formed in the frame element (RE), and the sealing element receptacle (DEA) is designed and / or formed to receive and hold the sealing element (DE) so that the sealing element (DE) seals against the conductor element (LE) when the frame element (RE) is pressed onto the top side (OS) of the printed circuit board (LP). [2] Electronic component according to claim 1, characterized by that the conductive element (LE) is an electrically conductive conductor track or electrically conductive conductor foil. [3] Electronic component according to one of the preceding claims, characterized by that the conducting element (LE) is an electrical component. [4] Electronic component according to one of the preceding claims, characterized bythat the frame element (RE) is at least partially materially connected to the upper side (OS). [5] Electronic component according to one of the preceding claims, characterized by that the frame element (RE) is made of a plastic and / or at least partially comprises plastic. [6] Electronic component according to one of the preceding claims, characterized by that the sealing element (DE) can be inserted and / or is inserted into the sealing element receptacle (DEA) starting from an outer side (AS) of the frame element (RE) facing away from the upper side (OS). [7] Electronic component according to one of the preceding claims, characterized by that the sealing element (DE) is at least partially cast with the overmold material (OMM). [8] Electronic component according to one of the preceding claims, characterized bythat in a wall of the sealing element receptacle (DEA), wherein the wall faces a section of the printed circuit board (LP) cast with the overmold material (OMM), a recess (VT) is formed, which is also cast with the overmold material (OMM). [9] Method for producing an electronic component (EB) according to one of the preceding claims, comprising the steps: - Providing a printed circuit board (LP) having a top side (OS), wherein an electrically conductive element (LE) is arranged on and / or in the top side (OS), - Arranging a frame element (RE) on the upper side (OS), which is designed to be recessed in the region of the guide element (LE), wherein a sealing element (DE) is arranged in the frame element (RE) in the region of the guide element (LE), wherein the sealing element (DE) has a lower rigidity than the frame element (RE), - Pressing the frame element (RE) against and / or onto the top side (OS) of the printed circuit board (LP) and the sealing element (DE) against and / or onto the guide element (LE), - Overmolding and / or potting the upper side (OS) at least in sections with an overmold material (OMM). [10] Method according to claim 9, characterized by that the step of pressing the frame element (RE) onto the top side (OS) and the step of partially overmolding the top side (OS) of the printed circuit board (LP) with the overmold material (OMM) take place simultaneously. [11] Method according to claim 9 or 10, characterized by that during the step of overmolding the upper side (OS), a temperature of greater than 80°, in particular greater than 100°C, acts on the upper side (OS) and / or the frame element (RE) and thereby a material connection between the frame element (RE) and the upper side (OS) is achieved. [12] Method according to one of claims 9 to 11, characterized bythat during the step of overmolding the upper side (OS), the sealing element (DE) is cast at least in sections in a sealing element receptacle (DEA) formed in the frame element (RE). [13] Use of an electronic component (EB) according to one of claims 1 to 9 in a transmission control unit (GSG) or in an inverter for a motor vehicle (KFZ). [14] Motor vehicle (KFZ) with an electronic component (EB) according to one of claims 1 to 9.

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