Electronic unit with electronic components and an arrangement for protecting them from pressure.

Abstract

Electronic unit comprising a printed circuit board (2) with at least one electronic component (5) arranged on a main surface (3, 4) of the printed circuit board (2) and with a casing element (7) which embeds the at least one electronic component (5), characterized in that a protective element (8) is present which is directly adjacent to the electronic component (5) on one side of the electronic component (5) facing away from the circuit board (2), that the protective element (8) is plate-shaped and rests against the top (5a) of the electronic component (5).

Description

[0001] The present invention relates to an electronic unit comprising electronic components and an arrangement for protecting the same from pressure exposure according to the main claim.

[0002] Current series applications for mechatronic control units utilize encapsulated electronics (e.g., a metal housing with glass feedthroughs) and signal and current distribution via stamped grids, stranded wires, or flexible printed circuit boards. Electronic control units are subject to a continuous trend toward lower prices while maintaining or increasing functionality. This necessitates the further development of existing solutions or the implementation of novel concepts. The connection technology between individual components is of particular interest, as the increasing miniaturization of electronic components also increases their susceptibility to dirt and vibrations. This is especially true in the automotive sector, where electronic components must function flawlessly with high reliability even under the most adverse operating conditions.

[0003] From DE 10 2013 215 368, an electronic unit comprising a printed circuit board and several electronic components arranged on the circuit board is known. To protect against environmental influences, the electronic unit is encapsulated, at least in the area of ​​the electronic components, with a shell element, e.g., a thermoset plastic. A disadvantage of this is that the overmolding process exerts high pressures on the electronic components, which can damage them.

[0004] DE 10 2010 036 910 A1 shows an electrical device with an assembly comprising a carrier and electrical components.

[0005] The object of the invention is to provide an electronic unit in which damage to the electronic components during the overmolding process is avoided.

[0006] This problem is solved by the subject matter of claim 1. Advantageous embodiments of the invention are the subject matter of dependent claims.

[0007] An electronic unit is proposed comprising a printed circuit board, at least one electronic component arranged on a main surface of the printed circuit board, and a casing element that encloses the at least one electronic component. According to the invention, a protective element is provided which rests directly against the electronic component on a side facing away from the printed circuit board.

[0008] A protective element is defined as an element that protects at least one side of an electronic component facing away from the printed circuit board (PCB) from mechanical impacts. A side facing away from the PCB is defined as a side of the electronic component that does not face a primary surface of the PCB. Specifically, a protective element is defined as a dimensionally stable element that does not bend, i.e., deform, when pressure is applied to one of its surfaces. Such a protective element ensures that the enclosure cannot exert pressure on the electronic component. Any pressure exerted by the enclosure towards the electronic component is thus absorbed and compensated for by the protective element.

[0009] In the following, electronic components are defined as those components used in a mechatronic control unit, particularly a transmission control unit. Specifically, electronic components are understood to be those in which one or more components are encapsulated by a housing. An example of such an electronic component is an electrolytic capacitor. An electrolytic capacitor consists of an aluminum housing containing a coil impregnated with electrolyte fluid and insulated from the outer wall. The electrical connections are routed through a seal on the underside of the component. The coil essentially consists of an anode foil, a cathode foil, and a spacer impregnated with electrolyte between them.

[0010] In the following, an encapsulation element is understood to be a cured potting compound, e.g., a thermoset. This potting compound is applied, at least partially, around the electronic unit using an overmolding tool. The potting compound is applied under high pressure, up to 50 bar, to encapsulate the electronic components and / or circuit board of the electronic unit. After the potting compound has cured, the encapsulation element is formed.

[0011] In one embodiment, the protective element can be cap-shaped and rest against several sides of the electronic component. This ensures that the protective element can optimally absorb the pressure acting on the electronic component. Furthermore, it ensures that no side of the electronic component is subjected to pressure, which could potentially damage the component. Particularly during an overmolding process, this prevents damage to the electronic components caused by the application of the potting compound to the circuit board and the electronic components under high pressure.

[0012] According to the invention, the protective element is plate-shaped and rests against the top surface of the electronic component. Advantageously, the protective element is designed as a plate that optimally covers the corresponding top surface of the component. This ensures that any pressure exerted on the top surface of the component during the overmolding process is optimally absorbed by the plate, thus preventing damage to the component. The plate can be made of metal or plastic.

[0013] In another embodiment, the protective element can be formed from a cured adhesive material. The adhesive material makes it possible to directly wet and stiffen the surface of the electronic component.

[0014] The adhesive material is applied and / or spread evenly over the surface of the electronic component. Curing of the adhesive material can be achieved using temperature and UV light.

[0015] However, it is also possible for the protective element to be made of metal or plastic, and it may be glued to the electronic component. The protective element can be designed to protect one or more sides of the electronic component from external pressure. It can be a single piece or consist of multiple parts.

[0016] In a further embodiment of the invention, a filler material can be arranged between the printed circuit board and the side of the electronic component facing the printed circuit board. This enables a mechanical connection and seal of the underside, i.e., the side of the electronic component facing the printed circuit board, to the printed circuit board. The same adhesive material, in particular epoxy material, which can also be used as a protective element for an electronic component, can be used as the filler material.

[0017] Another aspect of the invention is a transmission control system for motor vehicles with an electronic unit.

[0018] The invention will be explained in more detail below using figures. These show: Fig. 1 a schematic representation of an electronic unit in a first embodiment in sectional view, Fig. 2 A schematic representation of an electronic unit in a further embodiment in sectional view. Fig. 3 A schematic representation of an electronic unit in a further embodiment in sectional view.

[0019] Fig. Figure 1 shows a schematic representation of an electronic unit 1 in a first embodiment. The electronic unit 1 comprises a printed circuit board 2 and an electronic component 5 arranged on the printed circuit board 2. The printed circuit board 2 has a top surface 3 and a bottom surface 4. By way of example, an electronic component 5 is arranged on the top surface 3 of the printed circuit board 2. Of course, it is also possible that further electronic components (not shown) can be arranged on the bottom surface 4. The electronic unit 1 also has a casing element 7. The casing element 7 encloses the electronic component 5 on the top surface 4 of the printed circuit board 2. Furthermore, the casing element 7 also encloses partial areas of the bottom and top surfaces 3, 4 of the printed circuit board 2. This makes it possible, for example, to protect conductive traces (not shown) on the top or bottom surface 3, 4 of the printed circuit board 2 from environmental influences.

[0020] The encapsulation element 7 is applied to the printed circuit board 2 or around the electronic component 5 by means of an overmolding process. In this overmolding process, the overmolding material is applied to the printed circuit board 2 and / or components 5 under high pressure in an overmolding tool. As already explained, damage to the electronic component 5 can occur during this process without the application of the invention.

[0021] The electronic component 5 has electrical contacts (not shown) on its underside 5b, by which it is attached to the circuit board 2. A protective element 8 is applied to the top side 5a of the electronic component 5. The protective element 8 is, for example, made of an adhesive material, such as epoxy. The protective element 8 is attached to the top side 5a of the component 5. This prevents high pressure from the overmolding material on the top side 5a of the component 5 during the overmolding process and thus prevents damage to the electronic component. It is also possible, of course, for additional protective elements 8 to be attached to one or more other sides of the component 5.

[0022] A filler material 9 is inserted between the underside 5b of the electronic component 5 and the top side 3 of the printed circuit board 2. This filler material 9, e.g., epoxy material, serves to seal and fix the electrical connections (not shown) of the component 5 to the printed circuit board 2.

[0023] Fig. Figure 2 shows a schematic representation of an electronic unit 1 in a further embodiment. This further embodiment corresponds essentially to the first embodiment. The further embodiment differs in particular in the design of the protective element 8. The protective element 8 is cap-shaped and covers both the top surface 5a of the component 5 and the side surfaces of the component 5. In particular, the protective element 8 is dimensionally stable, so that it does not deform when pressure is applied during the overmolding process.

[0024] Fig.Figure 3 shows a schematic representation of an electronic unit 1 in a further embodiment. This further embodiment corresponds essentially to the first embodiment. The further embodiment differs in particular in the design of the protective element 8. The protective element 8 is plate-shaped and covers the top surface 5a of the electronic component 5. The protective element 8 can be bonded to the top surface 5a of the component 5. Reference sign 1 electronic unit 2 circuit boards 3 Top side of the circuit board 4 Underside of the circuit board 5 electronic component 5a Top side of the electronic component 5b Underside of the electronic component 7 Enclosure element 8 Protective element 9 Filling material

Claims

[1] Electronic unit comprising a printed circuit board (2) with at least one electronic component (5) arranged on a main surface (3, 4) of the printed circuit board (2) and with a casing element (7) which encloses the at least one electronic component (5), characterized by , that a protective element (8) is present which is directly adjacent to the electronic component (5) on one side of the electronic component (5) facing away from the circuit board (2), that the protective element (8) is plate-shaped and rests against the top (5a) of the electronic component (5). [2] Electronic unit according to claim 1, characterized by , that the protective element (8) is cap-shaped and rests against several sides of the electronic component (5). [3] Electronic unit according to any one of the preceding claims 1 to 2, characterized by , that the protective element (8) is formed from a cured adhesive material. [4] Electronic unit according to any one of the preceding claims 1 to 3, characterized by , that the protective element (8) is made of metal or plastic. [5] Electronic unit according to claim 4, characterized by , that the protective element (8) is bonded to the electronic component (5). [6] Electronic unit according to any one of claims 1 to 5, characterized by , that a filler material (9) is arranged between the circuit board (2) and the side of the electronic component (5) facing the circuit board (2). [7] Transmission control unit for motor vehicles comprising an electronic unit (1) according to any one of the preceding claims 1 to 6.

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