Electronic assembly, especially for electric or hybrid vehicles

Abstract

For an electronic assembly (1) comprising a plate-like support substrate (2) equipped with at least one heat-generating electrical and / or electronic component (5) on a top surface (3), a heat sink (6) and a heat transfer device (8) arranged between a bottom surface (4) facing away from the top surface (3) of the support substrate (2) and the heat sink (6) for transferring heat from the support substrate (2) to the heat sink (6) and for simultaneously electrically insulating the support substrate (2) from the heat sink (6), wherein the heat transfer device (8) comprises at least one planar thermally conductive film (30) with a first side (31) and a second side (32) facing away from the first side (31),and wherein the heat transfer device (8) further comprises at least one planar and electrically insulating insulating film (10) arranged on the first side (31) of the heat-conducting film (30) with an inner side (12) facing the first side (31) of the heat-conducting film (30) and an outer side (11) facing away from the inner side (12), it is proposed that at least one heat-conducting element (40) is arranged on the second side (32) of the heat-conducting film (30), wherein the heat-conducting element (40) extends planarly essentially parallel to the heat-conducting film (30) and the insulating film (10) in a plane (E) and is spring-elastic perpendicular to this plane (E) and is clamped between the second side (32) of the heat-conducting film (30) and the heat sink (6).

Description

State of the art

[0001] The invention relates to an electronic assembly, in particular for electric vehicles or hybrid vehicles, comprising the features of the preamble of independent claim 1.

[0002] Hybrid and electric vehicles utilize inverter and converter structures. For example, inverters are used to operate an electric motor, providing phase currents for the motor. The power modules can comprise a substrate with conductive traces, on which, for instance, power semiconductors are arranged. These semiconductors, together with the substrate, form an electronic unit. During operation, the electronic unit generates heat, which must be dissipated to a heat sink. Simultaneously, the electronic unit must be electrically insulated from the heat sink. In power electronics, insulating films, laminates, or ceramic substrates are used, for example, for heat transfer and insulation between the heat sink and the electronic unit.This often requires additional materials to compensate for tolerances and unevenness between the partners to be joined, while simultaneously achieving good thermal transfer.

[0003] For example, DE 43 36 961 A1 shows a heat transfer device that serves to dissipate heat from the electronic unit to a heat sink. The heat transfer device comprises an electrically insulating thermally conductive film and a metallic foil and can, for example, be inserted between the electronic unit and the heat sink, thus allowing the heat generated by the electronic unit to be dissipated to the heat sink.

[0004] Furthermore, documents DE 11 2005 000 748 T5, US 4 763 225 A and DE 10 2008 045 409 A1 disclose an electronic assembly, in particular for electric vehicles or hybrid vehicles. Disclosure of the invention

[0005] According to the invention, an electronic assembly is proposed. This assembly comprises a plate-like support substrate equipped with at least one heat-generating electrical and / or electronic component on a top surface, a heat sink, and a heat transfer device arranged between a bottom surface facing away from the top surface of the support substrate and the heat sink for transferring heat from the support substrate to the heat sink and for simultaneously electrically insulating the support substrate from the heat sink. wherein the heat transfer device comprises at least one planar thermally conductive film with a first side and a second side facing away from the first side, and wherein the heat transfer device further comprises at least one planar and electrically insulating insulating film arranged on the first side of the thermally conductive film, with an inner side facing the first side of the thermally conductive film and an outer side facing away from the inner side. According to the invention, at least one thermal conductor is arranged on the second side of the thermally conductive film, wherein the thermal conductor extends in a plane essentially parallel to the thermally conductive film and the insulating film and is designed to be spring-elastic perpendicular to this plane and is clamped between the second side of the thermally conductive film and the heat sink. Advantages of the invention

[0006] In the electronic assembly, the heat transfer device arranged between the substrate and the heat sink advantageously dissipates and simultaneously spreads heat, generated, for example, by the at least one heat-generating electrical and / or electronic component, via the plate-like substrate and the heat transfer device to the heat sink. At the same time, the plate-like substrate can advantageously be electrically insulated from the heat sink by the electrically insulating film arranged in the heat transfer device between the substrate and the heat sink. The heat transfer device, comprising the insulating film, the thermally conductive film, and the thermally conductive element, can, for example, be advantageously simply inserted between the substrate and the heat sink as a composite material.This enables a significantly simpler and more cost-effective production of the electronic assembly. Processes that would otherwise be necessary, such as dispensing thermal paste or lamination under pressure and temperature, are eliminated and can be advantageously replaced by simply inserting the heat transfer device between the substrate and the heat sink. Because the heat transfer element is designed to be spring-elastic perpendicular to its plane of extension, irregularities and tolerances on the heat sink and / or substrate are advantageously compensated for when the heat transfer device is inserted between the substrate and the heat sink. This allows for the advantageous creation of large contact areas between the heat sink and the heat transfer element, and between the substrate and the insulating film.This results in an advantageously good dissipation of heat from the support substrate via the heat transfer device to the heat sink.

[0007] Further advantageous embodiments and developments of the invention are made possible by the features specified in the dependent claims.

[0008] In a particularly advantageous embodiment, the heat conductor is provided with a planar structure to generate spring elasticity, wherein the planar structure comprises first support sections that bear directly and / or indirectly against the thermally conductive film, and second support sections that are supported against the heat sink. With a heat conductor designed in this way, the advantage arises that the heat conductor, through the first and second support sections, has good thermal contact with both the thermally conductive film and the heat sink, and the heat transfer device can simultaneously be easily clamped between the heat sink and the substrate.

[0009] If the planar structure is designed such that the first and second support sections alternate, uniform contact between the heat conductor and the heat sink, on the one hand, and between the heat conductor and the thermal interface material, on the other, can be ensured over an area extending parallel to the plane of the structure. Thus, heat emitted by the at least one heat-generating electrical and / or electronic component on the substrate can be dissipated to the heat sink virtually across the entire surface. The alternating arrangement across the entire surface of the insert ensures an advantageously short heat dissipation path between the substrate and the heat sink. Furthermore, the alternating first and second support sections allow the heat transfer device to be clamped advantageously, stably, and easily between the substrate and the heat sink.

[0010] A particularly advantageous design for the heat conductor is a sheet metal component with incisions, where the first support sections are formed in one plane and the second support sections are bent outwards from this plane. A heat conductor designed in this way can be manufactured advantageously simply and cost-effectively and is further characterized by its advantageously low weight and advantageously high flexibility.

[0011] If the second support sections are designed as tabs, the advantage is that the heat conductor can be manufactured advantageously simply, and second support sections designed as tabs can be advantageously easily bent out of a plane formed by the first support sections, for example, and can advantageously easily ensure both the spring elasticity of the heat conductor and an advantageously large contact area between the second support sections and the heat sink.

[0012] In a particularly advantageous embodiment, an electrically insulating frame is arranged on the inside of the insulating film, the frame having at least one inner recess. The heat-conducting film is arranged in the recess and is completely surrounded by the insulating frame in one plane. An insulating frame designed in this way can advantageously stiffen, stabilize, and thus protect the heat transfer device.

[0013] Advantageously, the insulating film can have an area where it extends beyond the thermally conductive film, with the inner side of the insulating film in this area directly and / or indirectly in contact with the insulating frame via an adhesive layer. Thus, the insulating film can be advantageously stretched by the insulating frame, thereby stabilizing and protecting the entire heat transfer device.

[0014] Furthermore, in a particularly advantageous embodiment, at least one additional insulating film is arranged on the outside of the at least one insulating film, with an adhesive layer between the insulating film and the additional insulating film. The at least one additional insulating film advantageously increases the electrical insulation between the substrate and the heat sink. The electrical insulation can be scaled according to the requirements of the respective electronic assembly by the number of additional insulating films. Furthermore, continuous and complete electrical insulation can be ensured by using additional insulating films.

[0015] If the thermal conductivity film and the thermal conductivity body have at least essentially the same surface area, the advantage arises that the heat generated on the substrate by the at least one heat-generating electrical and / or electronic component can be dissipated advantageously over a large area and effectively via the thermal conductivity film and the thermal conductivity body.

[0016] Furthermore, it is advantageous if the thermally conductive film covers the heat-conducting body at least in the area of ​​the second support sections. If, for example, the second support sections are not in direct contact with the thermally conductive film, these areas, where the thermally conductive film is not in direct contact with the heat-conducting body, can be advantageously bridged by the thermally conductive film, thus advantageously improving the overall thermal conductivity of the heat transfer device.

[0017] In a particularly advantageous embodiment, the inner side of the insulating film is bonded at least partially to the first side of the thermally conductive film and / or the second side of the thermally conductive film is bonded at least partially to the heat-conducting element, in particular to the first support sections. A heat transfer device designed in this way can form an advantageous composite material that can be easily and flexibly inserted between the substrate and the heat sink. Brief description of the drawings

[0018] Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. They show Fig. 1 an exploded view of an embodiment of the electronic assembly according to the invention, Fig. 2 a cross-section through the heat transfer device of the embodiment of the electronic assembly according to the invention, Fig. 3 a further cross-section through the heat transfer device of the exemplary embodiment of the electronic assembly, Fig. 4 a cross-section through the exemplary embodiment of the electronic assembly. Embodiments of the invention

[0019] Fig. Figure 1 shows an exploded view of an embodiment of the electronic assembly 1 according to the invention. The electronic assembly 1 can be used, for example, in electric vehicles or hybrid vehicles to cool inverters or converters. The electronic assembly 1 can also be used in low-voltage or high-voltage batteries, or, for example, in photovoltaic systems or wind turbines.

[0020] The electronic assembly 1 comprises a plate-like support substrate 2, equipped on a top surface 3 with at least one heat-generating electrical and / or electronic component 5, and having a bottom surface 4 facing away from the top surface 3. The support substrate 2, together with the at least one heat-generating electrical and / or electronic component 5, can form an electronic unit 9. The electronic unit 9, which can be, for example, a power electronics unit such as an inverter or converter for an electric vehicle or a hybrid vehicle, comprises the support substrate 2 and heat-generating electrical and / or electronic components 5 arranged on the support substrate 2. The support substrate 2 can comprise several layers of electrically conductive materials such as metals and / or diaelectric materials.The substrate 2 is, for example, a circuit carrier, in this embodiment a DBC substrate (Direct Bonded Copper). However, the substrate 2 could also be, for example, an AMB substrate (Active Metal Brazed), an IMS (Insulated Metal Substrate), a printed circuit board (PCB), or another substrate suitable, for example, for power modules. Various electrical and / or electronic components, such as power semiconductors like field-effect transistors such as MIS-FETs (Metal Insulated Semiconductor Field Effect Transistors), IGBTs (Insulated-Gate Bipolar Transistors), power MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors), and / or diodes, for example, rectifier diodes, can be arranged on the top surface 3 of the substrate 2. These components can, for example, be bare-die power semiconductors.Furthermore, passive components such as resistors or capacitors can also be arranged on the substrate 5. The electrical and / or electronic components can be electrically connected to each other or to other electrical and / or electronic elements located outside the electronic unit 9 and not shown in the figures, for example, via the conductor tracks of the substrate 5, bond wires, or other suitable electrically conductive contact elements, for example, by soldering or sintering. The conductor tracks can be designed as conductive surfaces, as in this exemplary embodiment. Only one heat-generating electrical and / or electronic component 5 is shown in the figures by way of example.

[0021] Furthermore, the electronic assembly 1 comprises, as shown in Fig. Figure 1 shows a heat sink 6. The heat sink 6 is made of a material with high thermal conductivity, for example a metal, for example aluminum.

[0022] As in Fig. As shown in Figure 1, a heat transfer device 8 is arranged between the heat sink 6 and the support substrate 2. The heat transfer device 8 serves to dissipate heat from the support substrate 2 to the heat sink 6 and simultaneously provides electrical insulation between the support substrate 2 and the heat sink 6. The heat transfer device 8 comprises an electrically insulating insulating film 10, a thermally conductive film 30, and a thermally conductive body 40, and may additionally include an insulating frame 20. The heat transfer device 8 is in Fig. 2 and Fig. 3 shown.

[0023] The thermally conductive foil 30 is planar and has a first side 31 and a second side 32 facing away from the first side 31. To improve the thermal conductivity of the heat transfer device 8, the thermally conductive foil 30 has a small thickness D30 in this embodiment. In this embodiment, the thickness D30 of the thermally conductive foil 30 is between seventy micrometers and ninety micrometers, particularly between seventy-five and eighty-five micrometers. The thermally conductive foil 30 is made of a material with high thermal conductivity, such as copper. However, the thermally conductive foil 30 can also be made of other materials with high thermal conductivity. In this embodiment, the thermally conductive foil 30 is planar and has no recesses.This ensures advantageously good heat distribution of the heat generated on the support substrate 2 by the at least one heat-generating electrical and / or electronic component 5 over the entire surface area of ​​the thermal conductivity film 30.

[0024] As in Fig. As shown in Figure 1, an insulating film 10 is arranged on the first side 31 of the thermally conductive film 30. The electrically insulating insulating film 10 is planar and has an inner side 12 facing the first side 31 of the thermally conductive film 30 and an outer side 11 facing away from the inner side 12. The insulating film 10 is made of electrically insulating material and electrically insulates the substrate 2 from the heat sink 6. In addition to the at least one insulating film 10, one or more further insulating films 13 can be arranged on the outer side 11 of the at least one insulating film 10, increasing the electrical insulation between the substrate 2 and the heat sink 6. For example, an adhesive coating 15 can be arranged between the insulating film 10 and the further insulating film 13, which bonds to the insulating film 10 and to the further insulating film 13 in a metallurgical bond. As shown in Figure 1, the insulating film 10 is formed in a planar manner. Fig. 3 and Fig. As shown in Figure 4, in this embodiment two further insulating films 13 are arranged on the outer surface 11 of the insulating film 10. The three insulating films 10, 13 are bonded together by adhesive deposits 15 placed between them. Any number of insulating films 10, 13 can be arranged on the first side 31 of the thermally conductive film 30. The electrical insulation between the substrate 2 and the heat sink 6 can be scaled by the number of insulating films 10, 13 according to the requirements of the respective electronic assembly 1.

[0025] A thermal element 40 is arranged on the second side 32 of the thermally conductive film 30. The thermal element 40 extends over a surface essentially parallel to the thermally conductive film 30 and the insulating film 10 in a plane of extension E. In the context of this application, a thermal element 6 is understood to be a single-piece or multi-part and mechanically connected component characterized by high thermal conductivity. The thermal element 6 can, for example, consist at least partially of a metal, such as copper, or of a thermally conductive plastic. Furthermore, the thermal element 40 is designed to be spring-elastic perpendicular to the plane of extension E. The thermal element 40 is clamped in the electronic assembly 1 between the second side 32 of the thermally conductive film 30 and the heat sink 6.In this embodiment, the spring elasticity of the thermal interface material 40 is generated by a planar structure formed on the thermal interface material 40, which extends, for example, in the plane E. In this embodiment, the planar structure has first support sections 41 and second support sections 42. In this embodiment, the first support sections 41 bear directly and / or indirectly against the thermal interface film 30. In this embodiment, the second support sections 42 are supported by the heat sink 5. Fig. 4) In this embodiment, the planar structure with which the heat conductor 40 is provided is designed such that the first support sections 41 and the second support sections 42 alternate. The planar structure with the first support sections 41 and the second support sections 42 can, for example, have a wave-like, a cupped, a zigzag, or a similar structure. In this embodiment, the heat conductor 40 is, for example, designed as a sheet with incisions 45, the first support sections 41 are formed in one plane, and the second support sections 42 are bent out of this plane. The incisions 45 can be produced by various methods, for example, by cutting or etching. As in Fig. As shown in Figure 2, in this embodiment the second support sections 42 are designed as tongue-like tabs 46. For this purpose, the incisions 45 in the heat-conducting body 40 are designed such that the second support sections 42 can be bent out of the heat-conducting body 40 as tabs 46. In this embodiment, the heat-conducting film 30 and the heat-conducting body 40 have essentially the same surface area. The heat-conducting film 30 covers the heat-conducting body 40 in the area of ​​the second support sections 42, where, in this embodiment, the second support sections 42 are bent out of the plane formed by the first support sections 41.Thus, the heat generated on the support substrate 2 by the at least one heat-generating electrical and / or electronic component 5 can be advantageously dissipated to the heat sink 6 even in areas where the thermal interface material 40 is not in direct contact with the support substrate 2 via the thermal interface film 30, such as in the area of ​​the second support elements 42. In this embodiment, the thickness D40 of the thermal interface material 40 is between seventy micrometers and ninety micrometers, particularly between seventy-five and eighty-five micrometers. This small thickness D40 advantageously increases the thermal conductivity of the heat transfer device 8.

[0026] Furthermore, the heat transfer device 8 of the electronic assembly 1 can comprise an electrically insulating frame 20. In this embodiment, such an insulating frame 20 is arranged on the inner surface 12 of the insulating film 10. In this embodiment, the insulating frame 20 has at least one inner recess 21. In this embodiment, the thermally conductive film 30 is arranged in the recess 21 and is completely surrounded by the insulating frame 20 in one plane. As in this embodiment, the insulating film 10 can also have a region 17 in which it projects beyond the thermally conductive film 30. The inner surface 12 of the insulating film 10 can thus directly and / or indirectly, via an adhesive layer 22, contact the insulating frame 20 in this region 17.In this embodiment, the insulation frame 20 has a thickness so thin that, when the heat transfer device 8 is clamped between the support substrate 2 and the heat sink 6, the insulating film 10 or at least one further insulating film 13 is in direct contact with the support substrate 2, and the thermal interface material 40 is in direct contact with the heat sink 6. In this embodiment, the thermal interface material 40 is clamped between the thermal interface film 30 and the heat sink 6.

[0027] In this embodiment, the inner surface 12 of the insulating film 10 is bonded to the first side 31 of the thermally conductive film 30. Simultaneously, the second side 32 of the thermally conductive film 30 is bonded to the thermally conductive body 40. In this embodiment, the second side 32 of the thermally conductive film 30 is also bonded to the first support sections 41 of the thermally conductive body 40. Thus, in this embodiment, the heat transfer device 8 is designed as a composite material and can be inserted between the substrate 2 and the heat sink 6. In this embodiment, the heat transfer device 8 can be placed onto the heat sink 6 or the substrate 2 manually or by means of a placement device in its finished state. In this embodiment, the heat transfer device 8 is therefore inserted between the substrate 2 and the heat sink 6 and thus rests against the underside 4 of the substrate 2 and the heat sink 6.The support substrate 2 can, for example, be mechanically attached to the heat sink 6 by means not shown in the figures, and can also be pressed against the heat sink 6 by these means. Thus, the heat transfer device 8 is clamped between the support substrate 2 and the heat sink 6, and the second support sections 42 of the heat conductor 40 bear directly or indirectly against the heat sink 6, thereby advantageously compensating for unevenness and tolerances in the support substrate 2 and / or in the heat sink 6.By clamping the heat transfer device 8 with the thermal conductor 40, which has a spring-elastic and planar structure, between the support substrate 2 and the heat sink 6, the heat transfer device 8 is in thermally conductive contact with the support substrate 2 via an insulating film 10, 13 and with the heat sink 6 via the second support sections 42 of the thermal conductor 40, so that the heat generated, for example, by the at least one heat-generating electrical and / or electronic component 5 on the upper surface 3 of the support substrate 2 can be dissipated from the support substrate 2 to the heat sink 6 via the heat transfer device 8. Fig. 3 and Fig. Figure 4 shows, by way of example, only a second support section 42. As shown from Fig.As can be seen on the heat conductor 40, and thus on the heat transfer device 8, a plurality of second support sections 42 are formed, which are supported on the heat sink 6. This plurality of second support sections 42 is formed alternately with a plurality of first support sections 41. Thus, the heat transfer device 8 can advantageously adapt to the unevenness in the support substrate 2 or the heat sink 6, so that the heat transfer device 8 is in large-area thermally conductive contact with the support substrate 2 and, via the second support sections 42 of the heat conductor 40, also in advantageously large-area thermally conductive contact with the heat sink 6, thus ensuring optimal heat dissipation.

[0028] Of course, further embodiments and hybrid forms of the illustrated embodiments are possible.

Claims

[1] Electronic assembly (1), in particular for electric vehicles or hybrid vehicles, comprising a plate-like support substrate (2) equipped with at least one heat-generating electrical and / or electronic component (5) on a top surface (3), a heat sink (6) and a heat transfer device (8) arranged between a bottom surface (4) facing away from the top surface (3) of the support substrate (2) and the heat sink (6) for transferring heat from the support substrate (2) to the heat sink (6) and for simultaneously electrically insulating the support substrate (2) from the heat sink (6), wherein the heat transfer device (8) comprises at least one planar thermally conductive film (30) with a first side (31) and a second side (32) facing away from the first side (31),and wherein the heat transfer device (8) further comprises at least one planar and electrically insulating insulating film (10) arranged on the first side (31) of the heat-conducting film (30) having an inner side (12) facing the first side (31) of the heat-conducting film (30) and an outer side (11) facing away from the inner side (12), characterized by , that at least one thermal conductor (40) is arranged on the second side (32) of the thermal conducting foil (30), wherein the thermal conductor (40) extends in a plane parallel to the thermal conducting foil (30) and the insulating foil (10) in a plane of extension (E) and is designed to be spring-elastic perpendicular to this plane of extension (E) and is clamped between the second side (32) of the thermal conducting foil (30) and the heat sink (6). [2] Electronic assembly according to claim 1, characterized by, that the thermal conductor (40) is provided with a planar structure to generate the spring elasticity, wherein the planar structure has first support sections (41) which are indirectly and / or directly adjacent to the thermal conductor film (30), and second support sections (42) which are supported on the heat sink (6). [3] Electronic assembly according to claim 2, characterized by , that the planar structure is designed such that the first support sections (41) and second support sections (42) occur alternately. [4] Electronic assembly according to one of claims 2 to 3, characterized by , that the heat conductor (40) is designed as a sheet with incisions (45), wherein the first support sections (41) are formed in one plane and the second support sections (42) are bent out of this plane. [5] Electronic assembly according to any one of claims 2 to 4, characterized by, that the second support sections (42) are designed as tabs (46). [6] Electronic assembly according to any one of the preceding claims, characterized by , that on the inside (12) of the insulating film (10) an electrically insulating insulating frame (20) is arranged, which has at least one inner recess (21), wherein the thermally conductive film (30) is arranged in the recess (21) and is completely surrounded in one plane by the insulating frame (20). [7] Electronic assembly according to any one of the preceding claims, characterized by , that the insulating foil (10) has an area (17) in which it extends beyond the thermally conductive foil (30), wherein the inside (12) of the insulating foil (10) in this area (17) is directly and / or indirectly in contact with the insulating frame (20) by means of an adhesive layer (22). [8] Electronic assembly according to any one of the preceding claims, characterized by, that in addition to the at least one insulating film (10) at least one further insulating film (13) is arranged on the outside (11) of the insulating film (10), wherein an adhesive coating (15) is arranged between the insulating film (10) and the further insulating film (13). [9] Electronic assembly according to any one of the preceding claims, characterized by , that the thermally conductive foil (30) and the thermally conductive body (40) have the same surface area. [10] Electronic assembly according to any one of claims 2 to 9, characterized by , that the thermal conducting film (30) covers the thermal conducting body at least in the area of ​​the second support sections (42). [11] Electronic assembly according to any one of claims 2 to 10, characterized by, that the inside (12) of the insulating foil (10) is bonded at least partially to the first side (31) of the thermally conductive foil (30) and / or the second side (32) of the thermally conductive foil (30) is bonded at least partially to the thermally conductive body (40), in particular to the first support sections (41).

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