Cooling arrangement for electrically non-insulated components of an electronic module, and assembly method

Abstract

A cooling arrangement for electrically non-insulated components of an electronic module is provided, comprising a support structure, at least one electrically non-insulated component arranged with its underside on the support structure and whose top side has an electrically non-insulated area, a cooling structure of at least three layers, comprising as the bottom layer a multi-part thermal interface material and as the top layer at least one thermal interface material, as well as as the middle layer an insulating layer, wherein a portion of the bottom layer is applied to the top side of each component, and wherein the middle layer and the at least one top layer are applied over the entire surface of the components. A heat-dissipating component is arranged on the top layer of the cooling structure.Furthermore, a mechanical fastening component is provided which mechanically connects the support structure and the cooling structure to the heat-dissipating component in such a way that the cooling structure is pressed against the heat-dissipating component with a predetermined pressure.

Description

[0001] The present invention relates to the field of electromobility, in particular the cooling of electrically non-insulated power semiconductor components of electronic modules.

[0002] Electrically non-insulated components such as power semiconductors, capacitors, and inductors are required in a wide variety of automotive applications. For example, they are used in power electronics modules in electromobility, which operate electric drives and function as converters (DC / AC, DC / DC, etc.) or filters. They are also used in other electronic modules that power other components of a vehicle or system. When using power semiconductors, as well as some filters and inductors, adequate cooling is essential, as overheating can damage the components.

[0003] Electronic modules frequently use non-insulated components, meaning components without an electrically insulating coating. These non-insulated components are attached to a heatsink or housing, for example via a gap filler, using a thermal interface material (TIM) as a connecting layer, and thus cooled. Electrical insulation between the component and the heatsink / housing is achieved either by the TIM itself, in which case a single TIM application is sufficient, or, for higher voltage classes, by an additional insulating layer (ceramic, insulating film, or similar). In this case, TIM must be applied to both sides of the insulating layer. The invention relates to the second case, involving two TIM layers with an insulating layer in between.

[0004] A problem with heat dissipation from components is the low thermal conductivity of conventional TIMs. The aim of the invention is to solve the problem of the low thermal conductivity of current TIMs without requiring an additional thermal process step to create a material-bonded connection (e.g., soldering) between the component and the insulation and / or housing.

[0005] This task is solved by the features of independent claims. Advantageous embodiments are the subject of dependent claims.

[0006] A cooling arrangement for electrically non-insulated components of an electronic module is provided, comprising a support structure, at least one electrically non-insulated component arranged with its underside on the support structure and whose top side has an electrically non-insulated area, a cooling structure of at least three layers, comprising as the bottom layer a multi-part thermal interface material and as the top layer at least one thermal interface material, as well as as the middle layer an insulating layer, wherein a portion of the bottom layer is applied to the top side of each component, and wherein the middle layer and the at least one top layer are applied over the entire surface of the components. A heat-dissipating component is arranged on the top layer of the cooling structure.Furthermore, a mechanical fastening component is provided which mechanically connects the support structure and the cooling structure to the heat-dissipating component in such a way that the cooling structure is pressed against the heat-dissipating component with a predetermined pressure.

[0007] In one version, the non-electrically isolated component is a power semiconductor component, a capacitor, or an inductor.

[0008] In one version, the heat-dissipating component is a heat sink or a housing for the electronic module.

[0009] In one version, the mechanical fastening component is formed as one or more clamps and / or screws and / or rivets.

[0010] In one embodiment, a protective cover is provided on the underside of the support structure facing away from the building elements and is mechanically connected to the support structure.

[0011] In one version, the mechanical fastening component also secures the protective cover.

[0012] In one version, the thermal interface material is multilayered and compressible.

[0013] Furthermore, an assembly method for mounting the cooling arrangement is provided, comprising the steps of attaching one or more of the components to the support structure, placing the parts of the bottom layer of the cooling structure onto electrically non-insulated areas of the components so that there is no electrical connection between the parts, placing the middle layer of the cooling structure completely over the bottom layer, placing at least one top layer of the cooling structure completely over the middle layer, applying the heat-dissipating component, and mechanically attaching at least the support structure to the heat-dissipating component in such a way that the cooling structure is pressed against the heat-dissipating component with a predetermined pressure.Alternatively, the assembly process comprises the steps of providing a heat-dissipating component, applying one or more top layers of the cooling structure over the entire surface of the heat-dissipating component, applying the middle layer of the cooling structure over the entire surface of the top layer, applying the parts of the bottom layer of the cooling structure to electrically non-insulated areas of the components, applying the components to the top layer and attaching the components to the support structure, or applying the components to the support structure and then applying the components together with the support structure to the top layer, mechanically attaching at least the support structure to the heat-dissipating component in such a way that the cooling structure is pressed against the heat-dissipating component with a predetermined pressure.

[0014] In one version, a protective cover is additionally provided on the side of the support structure opposite the building components and is mechanically attached to the heat-dissipating component.

[0015] Furthermore, an electronic module for use in a vehicle is provided, comprising the cooling arrangement.

[0016] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures in the drawing, which shows details of the invention, and from the claims. The individual features can be implemented individually or in any combination in a variant of the invention.

[0017] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying figures. Fig. Figure 1 shows a top view of a support structure with components to be cooled and a multi-part bottom layer for cooling according to an embodiment of the present invention. Fig. Figure 2 shows a side view of a support structure with components to be cooled and a middle and top layer for cooling according to an embodiment of the present invention. Fig. Figure 3 shows a view of a connection between the support structure with the cooling structure and a heat-dissipating component according to an embodiment of the present invention. Fig. Figure 4 shows a view of a fully assembled component according to one embodiment of the present invention.

[0018] In the following figure descriptions, identical elements or functions are marked with the same reference symbols.

[0019] As mentioned at the beginning, the problem of the low thermal conductivity of current TIMs should be solved without requiring an additional thermal process step to create a material-bonded connection (e.g. soldering) between the component and the insulation and / or housing.

[0020] To achieve this, so-called (compressible) metal TIMs are used as a cooling structure. These are metallic heat dissipation pads, which are consequently also electrically conductive. Therefore, for non-insulated components, the combination with an insulating layer is essential, resulting in a multi-layered cooling structure consisting of metal TIM layers with an insulating layer in between. The non-insulated components to be cooled are bonded to a substrate (e.g., PCB) using a metallurgical connection, for example, via SMT soldering.

[0021] Power semiconductor devices are typically the most important application. However, if other electrically non-insulated components, such as capacitors or inductors, also require heat dissipation, the design and assembly method can be applied as well. A combination of power semiconductor devices and other components requiring heat dissipation on the support structure can also be equipped with the cooling structure and mounted according to the assembly method.

[0022] The structure and assembly method (in one embodiment thereof) of the assembly (protective cover 7, support structure 1 with component 2, cooling structure 3-5, heat-dissipating component 6, mechanical fastening component 8) are described below with reference to Fig. 1 to 4 described.

[0023] In Fig. Figure 1 schematically depicts a support structure 1 on which the components 2 to be cooled and insulated, e.g., power semiconductor components, are arranged. The support structure 1 can be a printed circuit board (PCB) or another suitable structure, depending on the application. In addition to the components 2 to be cooled, other components (in particular electronic components) can be provided. The components 2 relevant to the invention are not (electrically) insulated. These are attached to the support structure 1 on one underside, e.g., by soldering, and have an electrically non-insulated surface on their upper side, which serves to be contacted with a cooling structure in order to cool the components 2. The cooling structure used for cooling is multilayered, with a bottom, multi-part metal layer (metal pad) 3 arranged on the electrically non-insulated surface, as shown in Figure 1. Fig. As shown in Figure 1, unconnected parts of the multi-part metal layer 3 (the Metal-TIM Pad) are placed onto the heat dissipation surface of each component 2, i.e., not attached to it, for example, via a gap filler, as before. The parts of the bottom layer 3 must not be in contact with each other, as otherwise an unwanted current flow could occur between the components 2 and, for example, cause a short circuit. The required insulating layer 4 is applied over the entire surface of the bottom layer 3 as the middle layer. One or more top metal layers 5 (Metal-TIMs) are then applied over the entire surface of this middle layer, as shown in Figure 1. Fig. 2 indicated. Both the insulating layer 4 and the uppermost metal layer(s) 5 are therefore applied over the entire surface of the lowermost, multi-part metal layer 3. The insulating layer 4 and the uppermost metal layer(s) 5, as well as the lowermost metal layer 3, are not fastened, but merely laid on top.

[0024] In one embodiment, a (multi-part) mounting frame 90, 91 can be provided, as shown in the figures. The support structure 1 is arranged on a part of the mounting frame 91, optionally being provided with a protective cover 7 on the side opposite the components 2, as clearly shown in Fig. 3 and Fig. Figure 4 shows the protective cover 7. It can be connected to the support structure 1 in a suitable assembly step, for example, before or after the components 2 are attached to the support structure 1. Alternatively, it can also be attached together with the heat-dissipating component 6, for example, in a final step of the assembly process. If the protective cover 7 is present, it also serves to press the cooling structure against the heat-dissipating component 6. The protective cover 7 essentially serves to protect the (underside of the) support structure 1 (with any components 2 arranged on it) from environmental influences.

[0025] As in Fig. 3 and Fig. As indicated in section 4, a second part of the mounting frame 90 can be attached to the side with the components 2 (if a mounting frame is present), which serves as a guide / limit for receiving layers 3-5. As shown in Fig. As indicated in Figure 3, the loose layer structure consisting of metal TIMs 3, 5 and the insulating layer 4 (the cooling structure made up of layers 3-5) is now connected to a heat-dissipating component 6, such as a housing for the electronic module or a heat sink. The heat-dissipating component 6 is applied to the cooling structure (as indicated by the arrow in Figure 3). Fig. 3 indicated), pressed against it and mechanically fastened to it by means of a suitable fastening component 8 (e.g. screws or clamps), as in Fig. 4 shown.

[0026] For the application of the package consisting of (optional) protective cover 7, support structure 1 and cooling structure 3-5, the optional part of the mounting frame 91, which holds the support structure 1, can be provided with corresponding guide elements 911.

[0027] However, for assembling the package or assembly, it is not necessary to provide a mounting frame 90, 91, as the assembly process can be automated and thus precise placement of the individual components is possible even without a mounting frame 90, 91. This is therefore only optional.

[0028] When securing the package consisting of (optional) protective cover 7, support structure 1, and cooling structure 3-5, it is important that the contact pressure is permanently ensured by a mechanical fastening component 8, such as screws or clamps. Ensuring this (mechanical) contact pressure is one of the most essential factors for guaranteeing the function of the (compressible) metal TIM used. The number and positioning of the fastening components 8 are determined by a specialist depending on the package design, e.g., by means of simulations, tests, or a combination thereof.

[0029] The assembly (the mounting) can of course also begin in reverse order and end with the placement of the components 2 or the support structure 1, e.g. a PCB, for the component 2.

[0030] The individual Metal-TIM layers 3 and 5 used are each multilayered and compressible. The compressibility of the Metal-TIM ensures a certain degree of tolerance compensation between the layers of the cooling structure and the components support structure 1 and heat-dissipating component 6. The cover layers (e.g., copper, indium, tin, etc.) of the Metal-TIM can be selected according to the operating temperature, thus preventing thermal overload of the cooling layer (layers 3 and 5). Another essential advantage over a metallurgical bond is the replaceability of the Metal-TIM or the associated component 2 (e.g., power semiconductor module / power semiconductor device) in the event of a failure or degradation of the assembly, as simple disassembly is possible. This further reduces costs, as the entire unit, including the cooler or circuit boards, does not need to be replaced.

[0031] Furthermore, this interchangeable cooling structure exhibits increased reliability in thermo-mechanical behavior due to the elastic, spring-like core of layers 3 and 5.

[0032] The advantage of the presented solution is the better heat dissipation of the components 2, especially power semiconductor components, due to the higher thermal conductivity of the metal layer made of Metal-TIM, compared to the use of a gap filler.

[0033] An advantage of the presented solution compared to a metallurgical bond (produced, for example, by a soldering or sintering process) to the insulation layer 4 is that no additional thermal process step is required to create the bond, which saves costs, process time, and material. This also avoids stresses in the system that could arise due to differing coefficients of thermal expansion between component 2 and insulation layer 4. Furthermore, the application of a wettable surface to the insulation layer 4 to create a metallurgical bond is eliminated, which further reduces costs and increases the range of possible insulation layer 4 options.

[0034] The cooling arrangement has a wide range of applications. In particular, it can be used in electronic modules that employ non-isolated power semiconductor components. These non-isolated power semiconductor components can act as inverters and be used both in power electronics for operating the vehicle's electric drive and in electronic modules for operating other vehicle components.

[0035] A vehicle using this cooling system can be a passenger car or a commercial vehicle (truck, bus, agricultural vehicle, etc.). The cooling system can also be advantageous in other applications, such as control systems for wind turbines or solar / photovoltaic systems. Reference symbol list 1 Support structure 2 electrically non-insulated components 3 bottom layer made of metal TIM 4 middle layer as insulation layer 5 top layer(s) of Metal-TIM 6. Heat-dissipating component 7 protective covers 8 mechanical fastening components 90, 91 Mounting frame 911 guide elements

Claims

[1] Cooling arrangement for electrically non-insulated components (2) of an electronic module, comprising: - a support structure (1), - at least one electrically non-insulated component (2) arranged with a bottom side on the support structure (1) and whose top side has an electrically non-insulated area, - a cooling structure of at least three layers, comprising as the bottom layer (3) a multi-part thermal interface material and as the top layer (5) at least one thermal interface material, and as the middle layer (4) an insulating layer, wherein for each component (2) a part of the bottom layer (3) is placed on the top side of the component (2), and wherein the middle layer (4) and the at least one top layer (5) are placed over the entire surface of the components (2), - a heat-dissipating component (6) arranged on the top layer (5) of the cooling structure, - a mechanical fastening component (8) which mechanically connects the support structure (1) and the cooling structure to the heat-dissipating component (6) in such a way that the cooling structure is pressed against the heat-dissipating component (6) with a predetermined pressure. [2] Cooling arrangement according to claim 1, wherein the non-electrically insulated component (2) is a power semiconductor component, a capacitor or an inductor. [3] Cooling arrangement according to one of the preceding claims, wherein the heat-dissipating component (6) is a heat sink or a housing of the electronic module. [4] Cooling arrangement according to one of the preceding claims, wherein the mechanical fastening component (8) is formed as one or more clamps and / or screws and / or rivets. [5] Cooling arrangement according to one of the preceding claims, wherein a protective cover (7) is provided on an underside of the support structure (1) facing away from the components (2) and is mechanically connected to the support structure (1). [6] Cooling arrangement according to claim 5, wherein the mechanical fastening component (8) also fastens the protective cover (7). [7] Cooling arrangement according to one of the preceding claims, wherein the thermal interface material is multilayered and compressible. [8] Assembly method for assembling a cooling arrangement according to any one of the preceding claims, comprising the steps: - Attaching one or more of the components (2) to the support structure (1), - Placing the parts of the bottom layer (3) of the cooling structure on electrically non-insulated areas of the components (2), - Place the middle layer (4) of the cooling structure completely over the bottom layer (3), - Applying at least one top layer (5) of the cooling structure over the entire surface of the middle layer (4), - Application of the heat-dissipating component (6), - mechanically fastening at least the support structure (1) to the heat-dissipating component (6) such that the cooling structure is pressed against the heat-dissipating component (6) with a predetermined pressure, or comprising the steps: - Providing a heat-dissipating component (6), - Applying one or more top layers (5) of the cooling structure over the entire surface of the heat-dissipating component (6), - Place the middle layer (4) of the cooling structure over the entire surface of the top layer (5), - Placing the parts of the bottom layer (3) of the cooling structure on electrically non-insulated areas of the components (2), - Applying the components (2) to the top layer (3) and attaching the components (2) to the support structure (1) or applying the components (2) to the support structure (1) and then applying the components (2) together with the support structure (1) to the top layer (3), - mechanically fastening at least the support structure (1) to the heat-dissipating component (6) in such a way that the cooling structure is pressed against the heat-dissipating component (6) with a predetermined pressure. [9] Assembly method according to claim 8, wherein a protective cover (7) is additionally provided on the side of the support structure (1) opposite the components (2) and mechanically attached to the heat-dissipating component (6). [10] Electronic module for use in a vehicle, comprising the cooling arrangement according to any one of claims 1 to 7.

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