Method for coupling a heat sink to a power component and control unit

Abstract

The invention relates to a method for coupling a heat sink to an electrical power component. In the method, a heat sink is thermally conductively connected to the power component. In the method, the heat sink is at least partially inserted into a housing through a housing opening and, with a collar formed onto the heat sink, is placed onto an opening edge surrounding the housing opening. Furthermore, in the method, the collar is sunk into the opening edge until a coupling surface of the heat sink touches a thermal contact surface of the power component, in particular the power semiconductor, or a thermally conductive layer covering the thermal contact surface of the power component, in particular the power semiconductor, to form a thermally conductive connection.

Description

State of the art

[0001] The invention relates to a method for coupling a heat sink to an electrical power component, in particular a power semiconductor switch, an electronic processing unit, in particular a microprocessor, microcontroller, or a capacitor. In the method, a heat sink is thermally conductively connected to the power component.

[0002] From DE 10 2013 2006 999 A1 of the applicant, a control unit for a motor vehicle is known, which has a housing with a thermally conductive housing wall, wherein the thermally conductive housing wall has an embossing in a region opposite a power semiconductor. Disclosure of the invention

[0003] According to the invention, in the method mentioned above, the heat sink is at least partially inserted into a housing through a housing opening and, with a collar formed, in particular, onto the heat sink, is placed onto an opening edge framing the housing opening. Furthermore, in the method, the collar is recessed, in particular melted, into the opening edge to such a depth—in particular by means of material deformation or material displacement—that a coupling surface of the heat sink contacts a thermal contact surface of the power component, in particular the power semiconductor, or a thermally conductive layer covering the thermal contact surface of the power component, in particular the power semiconductor, for a thermally conductive connection.

[0004] Advantageously, manufacturing tolerances, in particular a height step of the power semiconductor within the housing, can be compensated by means of the sinking or melting process of the heat sink into the housing wall.

[0005] Preferably, the housing is designed with such thick walls in the area of ​​the opening edge that manufacturing tolerances can be bridged by the heat sink sinking in. Preferably, the housing is tightly connected to the collar after sinking or melting in, in particular in a media-tight manner. Advantageously, no separate sealing materials need to be arranged between the collar of the heat sink and the housing.

[0006] Preferably, the heat sink is recessed into the housing by forming or displacing material from the housing material in the area of ​​the opening edge. This allows the heat sink to be brought close to the thermal contact surface of the power component with a minimal gap, thus advantageously reducing the heat transfer resistance.

[0007] The heat-conducting agent is preferably arranged, in particular applied, on the power component with a predetermined layer thickness. This advantageously allows a heat transfer resistance to be predetermined within a series of manufactured devices, in particular control units. Furthermore, this advantageously allows a series standard to be created in which the thermal conductivity of the heat transfer between the heat sink and the power component can be reliably determined.

[0008] It has been recognized that by keeping the gap between the power component and the heat sink as small as possible, efficient heat transfer from the power component to the heat sink can be achieved. Furthermore, various heat-conducting materials with different thermal conduction properties can be arranged in a predetermined layer thickness between the power component and the heat sink.

[0009] The sinking is preferably achieved by softening or melting the housing material. The softening or melting of the housing material is preferably achieved by heating the heat sink, or by friction welding or ultrasonic welding, in which the housing material is deformed or reshaped in the area of ​​the collar.

[0010] In another embodiment, the softening of the housing material can be achieved using a solvent. The solvent, for example, a hydrocarbon, can be applied to the opening edge and soften it. Advantageously, the softening can thus be achieved without heat radiation.

[0011] In another embodiment, the housing has a particularly pasty adhesive in the area of ​​the opening edge, so that the collar can be sunk into the adhesive until it touches the power component. Advantageously, a housing wall of the housing can be thin in the area of ​​the opening.

[0012] It has been recognized that in control units, electronic power components, in particular power semiconductor switches or microprocessors with high power dissipation, in particular more than 20 watts of power dissipation, more than 50 watts of power dissipation or more than 100 watts of power dissipation, or semiconductor switches in the power output stages of an inverter, can be coupled to a heat sink in a cost-effective manner using the method.

[0013] The power component, in particular the power semiconductor or the electronic processing unit, preferably has a particularly cuboid-shaped housing on which the thermal contact surface is formed as a particularly flat surface area. This advantageously allows heat loss from the surface area of ​​the power component to be dissipated, preferably by means of slug-up cooling.

[0014] In another embodiment, the power component can be coupled to the heat sink using slug-down heat dissipation. For this purpose, the heat sink can be coupled to a surface area of ​​a circuit board or circuit carrier that is thermally conductively connected to the power component. The thermally conductive connection is created, for example, using thermally conductive vias or a thermally conductive inlay incorporated into the circuit board. Advantageously, the power component can also be coupled to the heat sink using slug-down heat dissipation in a cost-effective manner.

[0015] The heat sink is preferably formed by a heat sink, a cooling plate, a thermally conductive cooling structure, a heat pipe, in particular a pulsating heat pipe, or a metal block. The heat sink is preferably made of aluminum or copper or an alloy comprising aluminum and / or copper. This advantageously allows the power component to be cooled in a cost-effective manner.

[0016] The electronic power component is preferably a power semiconductor. The power semiconductor is preferably a microprocessor designed to generate waste heat, a microcontroller, or a semiconductor switch, in particular a field-effect transistor or an IGBT (Insulated-Gate Bipolar Transistor). Advantageously, an electronic power component that generates waste heat can be cooled in electronic control units at low cost.

[0017] In the following, a power semiconductor is cited as an example of a power component. In another embodiment, the power component can be a processing unit, in particular a microprocessor, a microcontroller, an ASIC (Application-Specific Integrated Circuit), a SIP (System-In-Package), or a capacitor, in particular an intermediate circuit capacitor or a choke, each of which can generate heat loss. The power component can thus advantageously be cooled to protect against overheating.

[0018] In a preferred embodiment, the collar frames the thermal contact surface, so that the thermal contact surface preferably protrudes from the collar as a projection. The heat sink can thus advantageously be inserted into the housing opening with the projection, where it can make thermally conductive contact with the power semiconductor—in particular, the power semiconductor connected to the housing.

[0019] In a preferred embodiment, the collar has grooves or depressions into which the softened or molten housing material of the housing flows, or can flow. This advantageously creates a particularly intimate and media-tight connection between the heat sink and the housing. The depressions or grooves can be designed without undercuts or with undercuts. In the embodiment with undercuts, the housing material can advantageously be connected to the collar to form a positive fit.

[0020] The grooves or depressions are created, for example, by laser ablation, spark erosion, etching, or milling. The depressions with an undercut are created, for example, by laser ablation with a laser beam directed obliquely, particularly with a transverse component perpendicular to an orthogonal line, onto the collar surface. Advantageously, the depressions can be created in this way with minimal effort.

[0021] In a preferred embodiment, the collar is heated by laser beams or infrared rays before and / or after being placed on the opening edge of the housing, to at least the softening or melting temperature of the housing material. Advantageously, the composite of the heat sink and the housing can be produced in this way with minimal effort. Furthermore, the gap between the power semiconductor and the heat sink can be designed to be as small as possible.

[0022] In a preferred embodiment, the recesses in the collar are created using laser beams. This advantageously creates a flat, interlocking, positive connection between the heat sink and the housing edge, in particular the opening edge of the housing.

[0023] In a preferred embodiment, the recesses in the collar are produced by electroerosion. This advantageously allows a rough surface structure with recesses to be produced in the heat sink, particularly in the collar, with minimal effort.

[0024] In a preferred embodiment, the housing is a single housing, and the circuit board is inserted into a slot in the slot housing, so that the thermal contact surface of the power semiconductor is opposite the slot. This advantageously allows manufacturing tolerances in a device, particularly a control unit, to be compensated for with a slot housing in a cost-effective manner.

[0025] Preferably, after inserting the circuit board into the housing's insertion opening, an orthogonal projection of the housing opening falls onto the thermal contact surface. This advantageously allows the power component to be contacted with precise positioning using the heat sink.

[0026] In a preferred embodiment of the method, after positioning the circuit board in the housing until the housing opening and the thermal contact surface of the power semiconductor are aligned, the heat sink, in particular the heat sink, is inserted through the housing opening into the housing until the coupling surface of the heat sink touches the thermal contact surface of the power semiconductor or is opposite it with a small gap. This advantageously allows the circuit board to be accommodated in the housing with minimal effort.

[0027] In a preferred embodiment of the method, the circuit board is thermally conductively contacted by a further heat sink through a further housing opening on a side facing away from the power semiconductor. Further preferably, the circuit board can have thermally conductive feedthroughs, in particular vias, each of which couples to a power semiconductor and can thus be contacted by means of the further heat sink.

[0028] In a preferred embodiment of the method, a thermally conductive material, in particular a thermally conductive adhesive, applied to the thermal contact surface of the power semiconductor is cured by the heat stored by the heat sink. The heat stored in the heat sink is preferably introduced into the heat sink by means of the aforementioned laser beams and / or infrared rays, and can thus be stored by the heat sink at least until contact is made with the power semiconductor.

[0029] Advantageously, the manufacturing process can thus combine two process steps: sinking or melting the heat sink into the housing wall, and curing the thermally conductive material, in particular a thermally conductive adhesive, to create a bonded connection between the heat sink and the power semiconductor. The heat-curing thermally conductive material is, for example, an epoxy resin.

[0030] The invention also relates to a control unit for a vehicle, in particular produced using the method described above. The vehicle is preferably an electric vehicle or a hybrid vehicle. The control unit preferably comprises a housing and at least one power semiconductor accommodated in the housing. The housing has a housing opening in the region of the power semiconductor, with a heat sink, in particular a heat sink, protruding through the opening and making thermally conductive contact with the power semiconductor.

[0031] In the control unit, at least a portion of the heat sink is preferably recessed, in particular fused, into an opening edge of the housing surrounding the opening. More preferably, the opening edge is softened for this purpose. This advantageously creates a low heat transfer resistance between the heat sink and the power semiconductor, as well as a good seal between the heat sink and the housing.

[0032] In a preferred embodiment, the part of the heat sink, in particular a collar formed on the heat sink, has recesses and / or grooves for the flow or penetration of the softened or molten housing material. The recesses are preferably created by laser beams, by electroerosion, or by milling or drilling.

[0033] Advantageously, a particularly positive interlocking engagement can be formed between the heat sink and the housing, so that the joining partners, in particular the housing and the heat sink, are connected to one another in a media-tight manner and are firmly protected against thermal expansion.

[0034] The housing material is preferably a plastic material, in particular a thermoplastic. The thermoplastic is preferably an engineering thermoplastic or high-performance thermoplastic. The thermoplastic is preferably a PA plastic (PA = polyamide), a PBT plastic (PBT = polybutylene terephthalate), a PP plastic (PP = polypropylene), an ABS plastic (ABS = acrylonitrile butadiene styrene), a PEI plastic (PEI = polyether imide), a PET plastic (PET = polyethylene terephthalate), or a high-temperature thermoplastic, in particular a PEEK plastic (PEEK = polyether ether ketone), a PMMA plastic (PMMA = polymethyl methacrylate), or a PES plastic (PES = polyethylene sulfide).

[0035] In a preferred embodiment of the control unit, the control unit has a plug connection. The plug connection is preferably connected to the printed circuit board. Further preferably, the housing is sealed by means of the plug connection—in particular after the printed circuit board has been inserted into the housing up to the point opposite the housing opening and the thermal contact surface in an orthogonal projection. Advantageously, this allows a completely sealed housing to be provided at low cost, wherein manufacturing tolerances, in particular a gap when positioning the power semiconductor orthogonally to a flat extension of the printed circuit board, can be compensated for by means of the heat sink recessed or fused into the housing wall.

[0036] The invention will now be described below with reference to figures and further exemplary embodiments. Further advantageous embodiments will become apparent from a combination of the features described in the dependent claims and in the figures. Fig. 1 shows a method step for producing an electronic device, in particular a control device, in which a printed circuit board connected to a plug-in connection is inserted through an insertion opening into a plug-in housing and can thereby close the insertion opening; Fig. 2 shows that in Fig. 1, in which the printed circuit board is accommodated in the housing and the insertion opening is closed and a heat sink is inserted into the housing through a housing opening; Fig. 3 shows a process step in which the heat sink is heated and melts into a part of the housing to minimize the gap to a semiconductor component.

[0037] Fig. Figure 1 shows a method step 1 in which a printed circuit board 7, together with a plug-in connector 8 connected to the printed circuit board 7, is inserted through an insertion opening 6 of a housing 4, in particular a plug-in housing. A semiconductor 16, in particular a power semiconductor, for example a microprocessor or a semiconductor switch, is integrally connected, in particular soldered or sintered, to the printed circuit board 7.

[0038] The housing 4 has a housing opening 5, which is designed for the insertion of a heat sink. The housing 4 has a groove 11 or a recess, which is designed to at least partially accommodate and hold a circuit board edge of the circuit board 7. The circuit board 7 can be held by the groove 11 after being fully inserted into the housing 4.

[0039] In this exemplary embodiment, the plug connection 8 has a plurality of electrical contacts, of which one electrical contact 9 is designated as an example. The electrical contacts extend at least partially within a body, in particular the plastic body of the plug connection 8, and protrude from the plastic body with an end section. The plug connection 8 has a plug collar 10 that encloses the electrical contacts. In this exemplary embodiment, the plug connection 8 is thus designed as a plug. In another embodiment, the plug connection 8 can be designed as a socket.

[0040] Fig. 2 shows the Fig. 1 already shown components, in particular the housing 4, the circuit board 7 and the connector 8, which in Fig. 2 are pushed together in a method step 2. For this purpose, the printed circuit board 7 has been pushed through the insertion opening 6 into the housing 4, in particular into a cavity 26 enclosed by the housing 4, so deeply that the edge of the printed circuit board is received in the groove 11 and held there. The plug connection 8 thus closes the insertion opening 6 in the inserted position 8'.

[0041] In the inserted position 7' ​​of the circuit board 7, a projection 20, in particular an orthogonal projection, of the housing opening 5 falls on a thermal contact surface 18 of the semiconductor 16. The thermal contact surface 18 is covered in this embodiment with a thermally conductive agent 17, in particular thermally conductive paste or thermally conductive adhesive, so that the power semiconductor 16 in the inserted position 16' is surrounded by a heat sink, in particular a Fig. 2. The heat sink 12 has a coupling surface 14 for thermally conductive contact with the power semiconductor 16, in particular the thermal contact surface 18. The heat sink 12 is arranged in the Fig. 2, for insertion into the housing opening 5. The heat sink 12 has a collar 13 that frames the coupling surface 14 and is integrally formed on the heat sink 12. The heat sink 12 has, for example, cooling fins 27 that are integrally formed on the heat sink 12. The heat sink 12 is, for example, a metal heat sink, in particular an aluminum heat sink or a copper heat sink.

[0042] Fig. 3 shows the Fig. 2 already shown components, wherein the heat sink 12 is introduced through the housing opening 5 into the housing 4, in particular into the cavity 26. In the Fig. In step 3 shown in Figure 3, the heat sink 12 is subjected to a force by means of a hold-down device 23 and—in particular simultaneously or beforehand—at least partially heated by laser beams 22. In this exemplary embodiment, the collar 13 is irradiated by the laser beams 22 and thus heated. The collar 13 is designed to absorb the laser beams 22 and thus be heated.

[0043] The collar 13 is in Fig. 3 is placed onto a part of the housing 4, in particular an opening edge 19 of the housing 4, which surrounds the housing opening 5. The collar 13 can thus be pressed, in particular melted, into the opening edge 19 in the position 13' placed onto the opening edge 19 by means of the pressure application and / or the laser beams 22.

[0044] The collar 13 has, on a side facing the opening edge 19 and thus the housing, recesses 15 which are designed to receive softened or molten housing material so that the collar 13 can be firmly anchored to the opening edge 19 in a form-fitting manner in the attached position 13'.

[0045] In the mounted position 13', the collar 13 has penetrated, in particular melted, into the opening edge 19 to a depth 24. The depth 24 thus corresponds to a tolerance that—in particular without the countersinking process of the opening collar 13—is formed to form a gap between the coupling surface 14 and the thermal contact surface 18. The gap can thus be advantageously bridged by the collar penetrating the opening edge 19 of the housing 4.

[0046] In this embodiment, the laser beams 22 are generated by a laser 21. The laser 21 is, for example, a semiconductor laser or a CO2 laser.

[0047] By sinking, in particular melting, the collar 13 into the opening edge 19 of the housing, the housing opening 5 is advantageously sealed in a media-tight manner. In this exemplary embodiment, the insertion opening 6 is sealed tightly by means of the plug-in connection 8, in particular the collar 10.

[0048] A seal, in particular an elastomer seal, can be formed or formed on the plug connection 8, in particular the collar 10, for the media-tight closure of the housing 4.

[0049] In another advantageous embodiment, the collar 10 is integrally bonded to the housing by means of laser transmission welding. For this purpose, the collar can be designed to be transparent to the laser beams in such a way that the laser beams pass at least partially or completely through the collar to the housing, where they are absorbed, thus bonding, in particular fusing, the housing to the collar in the area of ​​the laser beams.

[0050] With step 3, Fig. 3, a control unit 25 is generated, which is designed to be media-tight at low cost. The layer thickness of the thermally conductive agent 17, in particular a thermally conductive paste or a thermally conductive adhesive, can thus be Fig. 1 shown step 1 may be predetermined.

[0051] In the Fig. In step 3 shown in Fig. 3, the heat sink 12, in the position placed on the heat contact surface 18, in particular the heat conducting means 17', can receive the heat received from the collar 13 by means of heat conduction, and the coupling surface 14, in the placed position 14', can conduct it into the heat conducting means 17, so that the heat conducting means 17 can be indirectly cured by means of the laser beams 22.

[0052] In another embodiment, the coupling surface 14 can be placed on the circuit board 7 instead of on the semiconductor 16, wherein the semiconductor 16 is connected to the circuit board 7 on a side of the circuit board opposite the heat sink, in particular the heat sink. In such an embodiment, the waste heat generated by the semiconductor 16 can be conducted through the circuit board 7 to the heat sink 12, for example, by means of thermally conductive via connections.

[0053] In addition to the Fig.In addition to the heat sink 12 shown in Figure 3, the control unit 25 can have further heat sinks, each of which is introduced into the housing through a housing opening of the housing 4 and is thermally conductively coupled there to the circuit board or to a semiconductor connected to the circuit board.

[0054] A heat sink 28, which projects into the cavity 26 and directly couples the circuit board 7, or to a heat conducting means connected to the circuit board 7, and waste heat from a semiconductor 29, which can be conducted from the semiconductor 29 through the circuit board 7 to the heat sink 28, are shown in dashed lines.

[0055] The control unit 25 can have the heat sink 28, which is thermally conductively coupled to the circuit board 7, independently or in addition to the heat sink 12.

[0056] A collar of the heat sink 28 is recessed or fused into a housing wall of the housing 15 to bridge the gap and eliminate tolerances, so that the heat sink 28 can make thermally conductive contact with the circuit board 7 and can thus absorb waste heat generated by the semiconductor 29 and conducted through the circuit board 7. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2013 2006 999 A1

[0002]

Claims

[1] Method (1, 2, 3) for coupling a heat sink (12) to an electrical power component, in particular a power semiconductor (16) or an electronic processing unit, in which the heat sink (16) is connected to the power component (16) in a thermally conductive manner, characterized by that the heat sink (12) is at least partially inserted into a housing (4) through a housing opening (5), and is placed with a collar (13) formed on the heat sink onto an opening edge (19) framing the housing opening (5), and the collar (13) is sunk into the opening edge (19) to such a depth - in particular by means of material deformation - until a coupling surface (14) of the heat sink (12) touches a thermal contact surface (18) of the power semiconductor (16), or a thermally conductive layer (17, 17') covering the thermal contact surface (18) of the power semiconductor (16, 16'), for the purpose of forming a thermally conductive connection. [2] Method (1, 2, 3) according to claim 1, characterized bythat the collar (13) has grooves or depressions (15) into which the softened or melted housing material of the housing (4) flows. [3] Method (1, 2, 3) according to claim 1 or 2, characterized by that the collar (13) is heated after and / or before being placed on the opening edge (19) of the housing (4) by means of laser beams (22) to at least the softening temperature or melting temperature of the housing material of the housing (4). [4] Method (1, 2, 3) according to one of the preceding claims, characterized by that the recesses (15) in the collar are produced by means of laser beams, in particular laser ablation. [5] Method (1, 2, 3) according to one of the preceding claims, characterized by that the recesses (15) in the collar (13) have undercuts. [6] Method (1, 2, 3) according to one of the preceding claims, characterized bythat the housing (4) is a plug-in housing and the printed circuit board (7) is inserted into a plug-in opening (6) of the housing (4) so ​​that the thermal contact surface (18) of the power semiconductor (16) is opposite the housing opening (5). [7] Method (1, 2, 3) according to one of the preceding claims, characterized by that the printed circuit board (7) is contacted in a thermally conductive manner by a further heat sink (28) through a further housing opening from a side facing away from the power semiconductor (16). [8] Method (1, 2, 3) according to one of the preceding claims, characterized by that a thermally conductive material (17), in particular thermally conductive adhesive, applied to the thermal contact surface (18) of the power semiconductor (16) is cured by means of the heat stored by the heat sink (12). [9] Control device (25) for a vehicle, in particular generated by means of the method according to one of the preceding claims 1 to 8, wherein the control device (25) has a housing (4) and a power semiconductor (16, 16') accommodated in the housing (4), wherein the housing (4) has a housing opening (5) in the region of the power semiconductor (16), and wherein a heat sink (12), in particular a heat sink, projects through the housing opening (5) and contacts the power semiconductor (16) in a thermally conductive manner, characterized by , that at least a part of the heat sink (12), in particular a collar (17), is sunk or melted into an opening edge (19) of the housing (4) surrounding the housing opening (5). [10] Control device (25) according to claim 9, characterized by that the part of the heat sink (12), in particular the collar (17), has recesses (15) for the inflow of the softened or molten housing material, which are produced by means of laser beams. [11] Control device (25) according to one of the preceding claims 9 or 10, characterized bythat a plug connection (8) is connected to the printed circuit board (7), by means of which the housing (4) is closed, in particular after the printed circuit board (7) has been inserted into the housing (4) until the housing opening (5) and the thermal contact surface (18) are opposite one another.

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