Electronic assembly, light module and method for assembling an electronic assembly

Abstract

The present invention relates to an electronic assembly (100) comprising at least one electronic component (1), in particular a light-emitting diode (10), on a printed circuit board (2). According to the invention, the assembly (100) has at least one cooling plate (3) as a heat sink for the electronic component (1), wherein the cooling plate (3) is connected to the printed circuit board (2) by means of at least one press fit.

Description

[0001] The present invention relates to an electronic assembly comprising at least one electronic component, in particular a light-emitting diode, on a circuit board. Furthermore, the invention relates to an associated light module and a method for constructing the electronic assembly. STATE OF THE ART

[0002] In numerous applications, electronic assemblies are equipped with powerful electrical loads as electronic components, for example, light-emitting diodes for light modules in automotive lighting systems. A major challenge is the dissipation of the heat released during operation of the electronic components. In the prior art, it is common practice to solder or glue the back of the circuit board carrier to a metallic heat sink so that the operating heat can be conducted into the heat sink and dissipated via this to the operating environment, particularly in combination with a fan directed at the heat sink. The use of such heat sinks disadvantageously increases the installation space required by the assembly and, in some applications, is also oversized given the improving efficiency of electronic components. DISCLOSURE OF THE INVENTION

[0003] It is the object of the present invention to propose a further development of an electronic assembly of the type mentioned at the outset and a method for its construction, wherein the assembly, including the elements provided for heat dissipation, should in particular have comparatively small dimensions.

[0004] This object is achieved based on an electronic assembly according to claim 1 and a method for its construction according to claim 13. Advantageous developments of the invention are specified in the dependent claims.

[0005] The invention includes the technical teaching that the assembly has at least one cooling plate as a heat sink for the electronic component, wherein the cooling plate is connected to the circuit board by means of at least one press connection.

[0006] The basic idea of ​​the invention is to replace the large-format heat sink known from the prior art with appropriately positioned cooling plates as dedicated local heat sinks, using the press-fit technology established for assembling printed circuit boards to create press-fit connections. One or more cooling plates can be assigned to each electronic component to be cooled, such that, depending on the operating heat to be dissipated, a "tailor-made" cooling performance is provided for each electrical load. The cooling plates are made, in particular, of a metal and preferably form a continuous metallically conductive connection to the respective assigned electronic component, so that the thermal resistance between the component and the cooling plate is as low as possible.

[0007] In particular, the press connection between the heat sink and the circuit board is arranged in the direct vicinity of the associated electronic component, so that the heat diffusion path to the heat sink is short and thus rapid heat dissipation is enabled.

[0008] Preferably, each cooling plate has a flat blade section and at least one pin-like press-in section by means of which the press connection to the circuit board is established, wherein the press-in section is formed in one piece and of the same material as the blade section. The blade section is provided to dissipate heat to the operating environment by means of radiation and in particular convection. For example, the blade section has edge lengths in the range of 5 mm to 50 mm and protrudes in particular from a rear side of the circuit board opposite the electronic component. The angle at which the blade section protrudes from the circuit board can be expediently adapted to the spatial conditions of the specifically intended installation environment of the assembly; in particular, the blade section can protrude at a right angle.In a further embodiment, the blade section can be bent or folded, particularly to utilize the limited installation space of the assembly as effectively as possible. In an embodiment of the assembly with a plurality of closely adjacent cooling plates, the orientation of the blade sections is preferably designed to utilize the chimney effect for the most efficient heat dissipation to the operating environment, i.e., the blade sections are oriented such that, in the intended installation position of the assembly, the heated air can rise between the blade sections.

[0009] The press-in section of the cooling plate is preferably designed in such a way that it is plastically deformed when the press connection with the circuit board is established and thus forms a thermally well-conducting and mechanically robust connection to the circuit board.

[0010] For the press connection to the cooling plate, the circuit board preferably has at least one metallized press-in hole, wherein the press-in hole extends continuously from the back to the front of the circuit board. For example, the circuit board has a carrier which is designed as a so-called “insulated metal substrate (IMS)” and comprises a metal plate, for example made of copper or aluminum, and an insulating layer, wherein the insulating layer electrically insulates the conductor tracks arranged on the carrier from the metal plate. When the press-in section of the cooling plate is pressed in, a metallically conductive press connection is created with the metal plate of the carrier. Alternatively, the carrier comprises an electrically insulating carrier body, for example made of a fiber-reinforced epoxy resin, and a metallic sleeve which serves to create the press connection with the press-in section is received in the press-in hole.In principle, the cooling plate used according to the invention can be connected to any type of printed circuit board, in particular to single-sided as well as double-sided or multi-layer printed circuit boards.

[0011] In a further embodiment, the heat sink has two press-fit sections, by means of which two press connections are established. The two press connections are arranged in direct proximity on both sides of the electronic component. By providing a second press-fit section, an additional channel is provided for heat dissipation from the electronic component, with both press-fit sections opening into the sheet section, through which the heat is dissipated to the operating environment.

[0012] Furthermore, the assembly can comprise a plurality of heat sinks for an electronic component, with the press connections of the heat sinks arranged symmetrically in the immediate vicinity of the electronic component. By selecting the specific number of heat sinks, the effective cooling performance can be easily adapted to the requirements of the component to be cooled.

[0013] A particular advantage of the teaching according to the invention is that the assembly can be designed without a large-area heat sink, i.e., without a heat sink that covers a large part of the back of the circuit board. The assembly according to the invention therefore has a significantly smaller envelope than prior art assemblies equipped with heat sinks. A further advantage of omitting a large-format heat sink is that the various cooling plates can be at different electrical potentials during operation of the assembly and no unwanted short circuits occur because the cooling plates do not touch one another. This simplifies the thermal contacting of electronic components that do not have a potential-free connection (“thermo slug”) because the cooling plates used according to the invention can easily be connected directly to the anode or cathode in a metallically conductive manner.

[0014] The invention further relates to a light module for a motor vehicle lighting device, comprising an electronic assembly according to one of the aforementioned embodiments, wherein the at least one electronic component is designed as a light-emitting diode. For example, the light module is designed as a matrix LED light module, and the assembly comprises a plurality of light-emitting diodes in a regular arrangement, wherein each light-emitting diode can be assigned one or more separate cooling plates.

[0015] In one embodiment, the light module comprises at least one micro-fan configured to dissipate heat from the at least one heat sink. This provides efficient heat dissipation of the LED while simultaneously maintaining a compact installation size for the light module.

[0016] Furthermore, the invention relates to a method for constructing an electronic assembly according to the invention, comprising at least the following method steps in a non-fixed order: - Providing the circuit board with at least one metallized press-in hole for establishing a press connection, - Applying the at least one electronic component, in particular a light-emitting diode, to the circuit board, and - Pressing the press-in section of the cooling plate into the press-in hole to form the press connection.

[0017] The press-fit technique for constructing the press-fit connection is known in principle in the prior art. The press-fit section of the heat sink has a larger cross-section diagonal than the metallized press-fit hole in the circuit board, and during the press-fit process, the press-fit section undergoes plastic deformation. This results in cold welding with the metallized press-fit hole, creating a gas-tight, corrosion-resistant, electrically conductive, and resilient mechanical connection, thus ensuring permanently low thermal resistance. The cooling plates can be provided, in particular, as stamped and bent components, such that the blade section and the press-fit section are formed as a single piece and made of the same material. PREFERRED EMBODIMENTS OF THE INVENTION

[0018] Further measures improving the invention are described in more detail below, together with the description of preferred embodiments of the invention and the figures. It shows schematically: Fig. 1 a cross-sectional view of a first embodiment of the assembly according to the invention, Fig. 2 a cross-sectional view of a second embodiment, and Fig. 3 a rear view of the second embodiment, and Fig. 4 a rear view of a third embodiment.

[0019] Fig. 1 shows a schematic cross-sectional view of a section of a first exemplary embodiment of the assembly 100 according to the invention, comprising the electronic component 1 in the form of a light-emitting diode on the printed circuit board 2, and the cooling plate 3 as a heat sink for the electronic component 1, wherein the cooling plate 3 is connected to the printed circuit board 2 by means of a press connection in direct proximity to the electronic component 1.

[0020] The circuit board 2 comprises the electrically insulating carrier 21, for example made of a fiber-reinforced epoxy resin, with a press-in hole extending continuously from the back to the front of the circuit board 2, which is metallized by the metallic sleeve 24 accommodated therein. Located on the front of the circuit board 2 are the conductor track 23 and the component 1 electrically contacted therewith.

[0021] The cooling plate 3 is made of metal and has the flat blade section 31 and the pin-like press-in section 32, by means of which the press connection to the sleeve 24 is established, wherein the press-in section 32 is formed in one piece and of the same material as the blade section 31. The blade section 31 protrudes at a right angle from the rear of the printed circuit board 2. Via the press connection between the press-in section 32 and the sleeve 24 and the contact between the sleeve 24 and the conductor track 23, there is a continuous metallically conductive connection between the cooling plate 3 and the electronic component 1. This enables efficient dissipation of the operating heat from the electronic component 1 into the blade section 31, via which the heat is ultimately dissipated into the operating environment of the assembly 100.The dimensions of the blade section 31 are adapted to the required cooling capacity, with the edge length 30 being, for example, in the range of 5 mm to 50 mm.

[0022] Fig. 2 shows a schematic cross-sectional view of a section of a second exemplary embodiment of the assembly 100 according to the invention. In contrast to the first exemplary embodiment, the cooling plate 3 has two press-in sections 32, by means of which two press-fit connections are established, wherein the two press-fit connections are arranged in direct proximity on both sides around the electronic component 1. Furthermore, the circuit board 2 is designed here as an IMS and comprises the metallic carrier 21 with the front-side insulation layer 22, on which the conductor track 23 is arranged. The press-fit connections are formed between the press-in sections 32 and the two press-fit holes in the metallic carrier 21.

[0023] Fig. 3 and Fig. 4 show, in a schematic rear view, sections of the second and a third exemplary embodiment of the assembly 100 according to the invention. The position of the electrical components 1 accommodated on the opposite front side of the circuit board 2 is shown by dashed circles. In conjunction with the previous cross-sectional views, the illustrations reveal the flat shape of the blade sections 31, whose edge lengths 30 are significantly greater than their thickness.

[0024] The third embodiment of the assembly 100 in Fig. 4 comprises, for each electronic component 1, a plurality of cooling plates 3 as heat sinks, the press connections of which with the circuit board 2 are arranged in groups symmetrically in the immediate vicinity of the respective electronic component 1. By providing such a plurality of heat sinks, the cooling performance assigned to each electronic component 1 can be expediently individualized.

[0025] The invention is not limited in its implementation to the preferred embodiments described above. Rather, a number of variants are conceivable, which utilize the presented solution even in fundamentally different embodiments. All features and / or advantages apparent from the claims, the description, or the drawings, including structural details and spatial arrangements, may be essential to the invention both individually and in a wide variety of combinations. List of reference symbols 100 electronic assemblies 1 electronic component 2 circuit board 21 carriers 22 Insulation layer 23 Conductor track 24 sleeve 3 cooling plate 30 edge length 31 sheet section 32 press-fit section

Claims

[1] Electronic assembly (100) comprising at least one electronic component (1), in particular a light-emitting diode, on a printed circuit board (2), characterized by that the assembly (100) has at least one cooling plate (3) as a heat sink for the electronic component (1), wherein the cooling plate (3) is connected to the circuit board (2) by means of at least one press connection. [2] Assembly (100) according to claim 1, characterized by that the press connection is arranged in direct proximity to the electronic component (1). [3] Assembly (100) according to claim 1 or 2, characterized by that the cooling plate (3) has a flat sheet section (31) and at least one pin-like press-in section (32) by means of which the press connection is constructed, wherein the press-in section (32) is formed in one piece and of the same material as the sheet section (31). [4] Assembly (100) according to claim 3, characterized bythat the blade section (31) of the cooling plate (3) protrudes from a rear side of the printed circuit board (2) opposite the electronic component (1). [5] Assembly (100) according to claim 3 or 4, characterized by that the cooling plate (3) has two press-in sections (32) by means of which two press connections are constructed, wherein the two press connections are arranged in direct proximity on both sides around the electronic component (1). [6] Assembly (100) according to one of the preceding claims, characterized by that the printed circuit board (2) has at least one metallized press-in hole for establishing the press connection with the cooling plate (3), wherein the press-in hole extends continuously from the rear to the front of the printed circuit board (2). [7] Assembly (100) according to one of the preceding claims, characterized by that the cooling plate (3) is in a metallically conductive connection to the electronic component (1). [8] Assembly (100) according to one of the preceding claims, characterized by that the assembly (100) has a plurality of cooling plates (3) as heat sinks for the electronic component (1), wherein the press connections of the cooling plates (3) are arranged symmetrically in the direct vicinity of the electronic component (1). [9] Assembly (100) according to one of the preceding claims, characterized by that the sheet section (31) of the cooling plate (3) has an edge length (30) in the range of 5 mm to 50 mm. [10] Assembly (100) according to one of the preceding claims, characterized by that the assembly (100) is designed free of a large-area heat sink. [11] Light module for a motor vehicle lighting device, comprising an electronic assembly (100) according to one of the preceding claims, wherein the at least one electronic component (1) is designed as a light-emitting diode. [12] Light module according to claim 11, characterized bythat the light module comprises at least one micro-fan which is designed to cool the at least one cooling plate (3). [13] Method for constructing an electronic assembly (100) according to one of claims 1 to 10, comprising at least the following method steps in a non-fixed order: - Providing the printed circuit board (2) with at least one metallized press-in hole for establishing a press connection, - applying the at least one electronic component (1), in particular a light-emitting diode, to the printed circuit board (2), and - Pressing the press-in section (32) of the cooling plate (3) into the press-in hole to form the press connection.

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