Electronic unit with circuit board

Abstract

Electronic unit with a printed circuit board (2) with at least one component (5, 6) arranged on a main surface (3, 4) of the printed circuit board (2) and with an encasing element (7) which embeds the at least one component (5, 6), wherein the electronic unit (1) comprises a single printed circuit board (2), characterized in that the encasing element (7) is formed only in sections on a first main surface (3) and a second main surface (4) of the single printed circuit board (2) in such a way that the encasing element (7, 8) extends through openings (9) in the printed circuit board (2), wherein an electronic component (5) is encapsulated from an external environment in a fluid-tight manner by the encasing element (7), and a heat dissipation element (6) is at least partially enclosed by the encasing element (7), wherein the heat dissipation element (6) has undercuts (14) which are enclosed by the encasing element (7, 8).

Description

The present invention relates to an electronic unit with printed circuit board according to the main claim.Current series applications for mechatronic control units use encapsulated electronics (e.g. a metal housing with glass feedthroughs) and distribution of signals and currents via stamped grids, stranded wires or flex printed circuit boards. Electronic control units are constantly being subject to the trend of becoming increasingly more favorable in price with the same or increasing range of functions. This requires a further development of existing solutions or the use of novel concepts. In this case, in particular the connection technology between individual components is of increased interest, since with increasing miniaturization of the electronic components the susceptibility to dirt and vibrations also increases. This applies in particular in the field of vehicle technology, in which electronic components with a high reliability must function without faults even under most adverse operating conditions.An electronic unit is known from DE 10 2013 212 265.9, which is not prepublished, which comprises a distributor circuit board and a sub-rack circuit board. In this case, it is necessary for connection regions to be provided at which the distribution printed circuit board and the sub-rack printed circuit board are connected to one another. The disadvantage here is the increasing number of individual parts which form the electronic unit.U.S. Pat. No. 7,473,585 B2 discloses a substrate, on the first side of which an integrated circuit is mounted. The substrate has a hole near an outer edge of the integrated circuit. The substrate is over-molded with an over-mold material that enters through the hole to substantially underfill the integrated circuit.It is an object of the invention to specify an electronic unit which has the smallest possible number of individual parts with high stability.This object is achieved with the subject matter of the applicable claim 1. Advantageous embodiments of the invention are the subject matter of dependent claims.In the present case, a mechatronic concept with a central printed circuit board is proposed. In this case, it is proposed in particular that all the components required in the electronic unit are arranged on a single printed circuit board. Here, a single printed circuit board is understood to mean that all electronic components, heat sinks, sensors and connection elements for external devices are arranged on a single printed circuit board. This printed circuit board is in particular formed in one piece and can also be formed as a multilayer printed circuit board.In particular, an electronic unit is proposed having a printed circuit board with at least one component arranged on a main surface of the printed circuit board and with an enveloping element which embeds the at least one component, wherein the electronic unit comprises a single printed circuit board and the enveloping element is formed at least in sections on a first main surface and a second main surface of the single printed circuit board in such a way that the enveloping element passes through at least one opening in the printed circuit board.The printed circuit board expediently has at least one electronic component on one of the two main surfaces in each case. Such an embodiment offers the advantage of a further degree of freedom, in particular for double-sided mounting of the printed circuit board, whereby the flexibility in the production of the electronic unit is increased.The approach presented here offers the advantage that all components required in the electronic unit, which is in particular a control device, expediently an integrated transmission control for a motor vehicle, which components can be electronic components or heat dissipation elements (cooling elements) in an embodiment of the present invention, are applied to a single printed circuit board. As a result, the connection points between different printed circuit boards required in the prior art are avoided. The construction of the electronic unit according to the invention can thus be effected more favorably, more quickly and with a smaller structural size.A further advantage of the approach presented here is that special configurations can be presented without problems. This means that different printed circuit board geometries can be flexibly adapted to the respective installation condition in the transmission. The regions with electronic components can be formed flexibly. The injection-molded regions on the upper side and the lower side of the printed circuit board can be designed to be of different sizes.Due to the openings in the printed circuit board, during the injection molding process, a high stability is produced between the underside and the upper side of the printed circuit boards. In this case, the surfaces which are injection-molded on the top side and the underside can have different shapes and dimensions.In one embodiment of the invention, the electronic component is encapsulated in a fluid-tight manner by the enveloping element from an external environment, and the heat dissipation element is at least partially enclosed by the enveloping element.In a further embodiment of the invention, at least one further component is surrounded by the enveloping element or a further enveloping element separated from the enveloping element or embedded in the enveloping element or the further enveloping element. In addition, the further enveloping element can be produced from a different material than the enveloping element, in particular wherein the further enveloping element is formed by a metal housing. This makes it possible to ensure individual adaptation of the geometry of the electronic unit. By using different materials for the enveloping element and the further enveloping element, different protection requirements or radiation properties of different circuit parts of the electronic unit can also be taken into account, for example.Sensors can expediently be formed on the printed circuit board by the enclosure of electronic components. As a result, sensors which are usually applied as individual parts to a printed circuit board can be injection-molded directly onto the printed circuit board. This makes it possible to save material costs and placement times.In a further embodiment of the invention, the enveloping element fills a region between an outer surface and a main surface region of the printed circuit board and / or the component and a main surface region of the printed circuit board. Expediently, the enveloping element is formed by a potting compound or encapsulation compound. Filling all the cavities between the printed circuit board and a component likewise increases the stability of the electronic unit. The outer surface here means that surface which is formed by the injection molding compound after carrying out an injection molding process.In a further embodiment of the invention, the heat dissipation element has undercuts which are surrounded by the enveloping element.The invention and further advantages of the invention are explained in more detail below with reference to figures. The following are shown: FIG. 1 shows a schematic illustration of an electronic unit in a first embodiment in a sectional illustration, FIG. 2 shows a schematic illustration of an electronic unit in a second embodiment in a sectional illustration, FIG. 3 is a schematic plan view of an electronic unit according to the second embodiment. FIG. 4 shows a schematic illustration of an electronic unit in plan view with apertures.FIG. 1 shows a schematic illustration of an electronic unit in a first embodiment. On a printed circuit board 2, a component 5, 6 and an enveloping element 7, which encloses the component 5, 6, are arranged on a main surface 3, 4. Expediently, an electronic component 5 is arranged on each of the two main surfaces 3, 4 of the printed circuit board 2, i.e. from the upper side 4 and the lower side 3 of the printed circuit board 2. The mounting of the circuit board 2 on both sides results in advantages with regard to the packing density of the electronic unit.Perforations 9 are formed in the printed circuit board 2, which lead from the upper side 4 to the lower side 3 of the printed circuit board 2. These perforations 9 are expediently formed in the region around the individual electronic components 5, but can also be formed in the edge region of the printed circuit board 2. Expediently, the perforations 9 are uniformly distributed in the printed circuit board 2, in particular corresponding to a honeycomb structure. However, it is also possible for more or fewer perforations 9 to be formed around specific electronic components 5. The perforations 9 can expediently be designed according to a predetermined pattern. The apertures 9 are in particular configured as a bore. However, it is also possible for the apertures 9 to be designed as straight or arc-shaped slots.The electronic unit 1 has an enveloping element 7, which encloses the electronic components 5. The enveloping element 7 is expediently made of a material (e.g. thermosetting plastic) which meets predetermined protection requirements, e.g. water- and / or oil-tightness, but also predetermined radiation properties. The enveloping element 7 is formed on the upper side 4 and the lower side 3 of the printed circuit board 2. The material 10 of the enveloping element 7 fills the openings 9 in the printed circuit board 2 and the region between the electronic components 5 and the printed circuit board 2. the enveloping element 7 expediently encloses the printed circuit board 2 completely, but it is also possible for the enveloping element 7 to be formed only in sections on the upper side 3 and lower side 4 of the printed circuit board 2. Because the material 10 of the enveloping element 7 fills the apertures 9 in the printed circuit board 2, the enveloping element is formed as a one-piece element. This results in a direct connection of the enveloping element section 7 on the underside 4 with that enveloping element section 7 on the upper side 3, whereby an increased stability of the entire enveloping element 7 and thus also of the printed circuit board 2 is achieved.The height of the electronic unit 1 can be defined by the thickness of the enveloping element 7. This also fixes the outer surface 16 of the electronic unit 1.Further connection areas 15 for plugs 12 or sensors 11 are provided on the printed circuit board 2. For this purpose, corresponding blind or through-holes 16 are provided in the printed circuit board 2, which are expediently provided with an electrically conductive layer, so that an electrical connection can be produced between the plug 12 or the sensor 11 and the conductor tracks present on or in the printed circuit board 2. Open contact points 13 on the printed circuit board 2, e.g. soldering points, are expediently likewise surrounded by means of an enveloping element (e.g. thermosetting plastic). The connectors 12 or sensors 11, e.g. rotational speed, displacement, pressure or temperature sensors, can be connected to the printed circuit board 2 by means of crimping, riveting, soldering, welding, press-fit or plug-in connections.On the printed circuit board 2, a heat dissipation element 6, for example a heat sink, is arranged on the underside 4. This heat sink 6 is likewise at least partially surrounded by the enveloping element 7. A section of the cooling body 6 does not have a casing of the casing element 7. Thus, the heat can flow off unimpeded. However, it is also possible for the cooling body 6 to be completely surrounded by the enveloping element 7. The region B between the printed circuit board 2 and the cooling body 6 is likewise filled with the material 10 of the enveloping element 7.The cooling body 6 has undercuts 14, which are filled with the material 10 of the enveloping element 7 and are thus surrounded by the enveloping element 7. This ensures further stability of the electronic unit 1. Further, the heat sink 6 is held and fixed in position. The heat sink 6 can be connected by one surface directly to an electronic component 5 or via a thermal material 19.FIG. 2 shows a schematic illustration of an electronic unit 1 in a second embodiment in a sectional illustration. In this embodiment, as in FIG. 1, a plurality of electronic components 5 are arranged on a single printed circuit board 2. The electronic components 5, however, are surrounded by two enveloping elements 7, 8. The one enveloping element 7 encloses a first group of electronic components 5 and the further enveloping element 8 encloses a second group of electronic components 5. Each enveloping element 7, 8 expediently encloses a cooling body 6 in addition to the respective electronic components 5. The configuration of the cooling bodies 6 corresponds to the configuration as already explained in FIG. 1.The electronic unit 1 is furthermore designed in such a way that the printed circuit board 2 has apertures 18 which serve for fastening the electronic unit to a carrier plate, for example for a transmission. In addition, apertures 16 are formed in the printed circuit board 2 for fastening sensors, motors, valves or plugs (FIG. 3 ).FIG. 4 shows the printed circuit board 2 of an electronic unit 1 having a plurality of apertures 9. In the present example, the enveloping element 7 envelopes the entire printed circuit board 2, i.e. the entire electronic unit 1 is surrounded by the enveloping element 7, the enveloping element 7 thus covers the upper side 3 and the lower side 4 of the printed circuit board 2. In this case, the section of the enveloping element 7 on the upper side 3 and the section of the enveloping element 7 on the lower side 4 do not have to be symmetrical, provided that the two parts of the enveloping element 7 are connected at least by an aperture 9 filled with the injection molding compound 10.FIG. 4 also shows that the perforations 9 within the enveloping element 7 form a regular pattern, for example a honeycomb pattern. This arrangement of the perforations 9 achieves increased stability in the printed circuit board 2, so that distortions of the printed circuit board 2 are avoided.Reference numerals denote reference numerals1 Electronic unit 2 Printed circuit board 3 Upper side 4 Lower side 5 Electronic component 6 Heat dissipation element 7 Enveloping element 8 Further enveloping element 9 Aperture 10 Injection molding compound 11 Sensor 12 Plug 13 Injection molding at open contact point 14 Undercut 15 Connection region 16 Bores for plugs / sensors 17 Outer surface 18 Apertures for fastening 19 Thermal material B region between printed circuit board and heat dissipation element

Claims

Electronic unit having a printed circuit board (2) with at least one component (5, 6) arranged on a main surface (3, 4) of the printed circuit board (2) and with an enveloping element (7) which embeds the at least one component (5, 6), wherein the electronic unit (1) comprises a single printed circuit board (2), characterized in that the enveloping element (7) is formed only in sections on a first main surface (3) and a second main surface (4) of the single printed circuit board (2), in such a way that the enveloping element (7, 8) passes through openings (9) in the printed circuit board (2), wherein an electronic component (5) is encapsulated in a fluid-tight manner by the enveloping element (7) from an external environment and a heat dissipation element (6) is at least partially enclosed by the enveloping element (7), wherein the heat dissipation element (6) has undercuts (14) which are enclosed by the enveloping element (7, 8).Electronic unit according to Claim 1, characterized in that the openings (9) within the enveloping element are distributed regularly, in particular in the form of a honeycomb, in the printed circuit board (2).Electronic unit according to one of the preceding claims, characterized in that the openings (9) are uniformly distributed in the printed circuit board (2).Electronic unit according to one of the preceding claims, characterized in that the openings (9) are designed as straight or arc-shaped slots.Electronic unit according to one of the preceding claims, characterized in that the enveloping element (7) fills a region between an outer surface and a main surface region (3, 4) of the printed circuit board (2) and / or the component (5, 6) and a main surface region (3, 4) of the printed circuit board (2), in particular wherein the enveloping element (7) is formed by a potting compound or encapsulation compound.Electronic unit according to one of the preceding claims, characterized in that at least one further component (5) is surrounded by the enveloping element (7) or a further enveloping element (8) separated from the enveloping element (7) or is embedded in the enveloping element (7) or the further enveloping element (8), in particular wherein the further enveloping element (8) is produced from a different material than the enveloping element (7), in particular wherein the further enveloping element (8) is formed by a metal housing.Electronic unit according to one of the preceding claims for an integrated transmission control for motor vehicles.

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