ELECTRICAL ASSEMBLY AND METHOD FOR MANUFACTURING AN ELECTRICAL ASSEMBLY

Description

[0001] The invention relates to an electrical or electronic assembly with a flexible wiring carrier and a method for producing such an electrical assembly.

[0002] Nowadays, electrical and electronic assemblies and circuit arrangements are not only becoming increasingly complex, but they are also being further miniaturized and their performance increased. This combination of requirements gives rise to various problems in assembly and connection technology as well as in the operation of the corresponding assemblies or circuits. For example, assembly concepts are increasingly being used in which semiconductor elements are mounted directly, i.e. are not encapsulated in a corresponding housing. It has previously been common practice to connect the connections or contacts of the semiconductor elements mechanically, thermally and electrically using planar material-to-material connections. In this way, a tolerance chain can be built up across a large number of components.Maintaining a specified final tolerance, such as a possible joint height on the top surface of a semiconductor, often places critical and difficult-to-comply demands on the tolerance-affected components. Today, this often already reaches the limits of sensible, efficient, and cost-effective manufacturing.

[0003] Another increasingly relevant challenge is the thermomechanical behavior of such assemblies or circuits. For functional reasons, materials or components with widely differing thermal expansion coefficients often have to be used. These can be, for example, glass fiber or epoxy materials for organic wiring carriers with a thermal expansion coefficient of approximately 15-18×10 -6< K -1< , aluminum oxide ceramics with a thermal expansion coefficient of approximately 7×10 -6< K -1<, or even aluminum, frequently used for heat sinks, with a thermal expansion coefficient of approximately 23×10 -6< K -1<. In conventional assemblies or structures, these or similar materials can be bonded together to ensure mechanical, thermal, and electrical functionality.Particularly at temperatures beyond the joining temperatures and / or with temperature differences between the different materials, as can occur during regular operation, the different thermal expansion coefficients, i.e. the differences in the respective thermomechanical behavior, can lead to undesirable incorrect expansions, i.e. expansion differences that cause damage.

[0004] A well-known approach to solving these problems is material-geometric optimization. This approach attempts to overcome these problems through the clever arrangement and selection of different materials. For example, if significantly different expansions or changes in expansion are expected, joining materials with particularly high alternating load capacity, such as enhanced-performance brazing materials or sintered materials, can be used, or materials with significantly different expansion coefficients can be avoided altogether. However, this can lead to significantly increased costs and / or limited functionality. Furthermore, this approach is not arbitrarily scalable with increasing miniaturization and performance improvements.

[0005] WO 03 / 0 323 91 A2 describes a method for forming a package for electronic components and such a package. The package comprises several elements stacked in layers, including a cooling element, a flexible substrate supporting an electrically conductive layer and an electronic component, an electrically insulating gap filler, and a lid. Pressure is applied to this stacked arrangement to establish mechanical contact between the flexible substrate and the heat sink.

[0006] From US 2015 / 049443 A1, a chip arrangement is known which may comprise a first carrier; at least one chip arranged above the first carrier; a flexible structure having a wiring layer structure; and a contact structure arranged between the first carrier and the wiring layer structure, wherein the at least one chip is electrically coupled to the first carrier via the wiring layer structure and the contact structure.

[0007] The object of the present invention is to provide an electrical assembly with particularly good thermomechanical behavior, which can be manufactured precisely with particularly little effort and at the same time enables flexible, even complex functionality.

[0008] This object is achieved according to the invention by the subject matter of the independent patent claims. Advantageous embodiments and further developments of the invention are specified in the dependent patent claims as well as in the description and the drawings.

[0009] An electrical assembly according to the invention has at least one electronic switching element, which is electrically contacted on its underside and arranged on a flexible first wiring carrier of the electrical assembly. According to the invention, it is provided that the electronic switching element is additionally electrically contacted on an upper side opposite the underside. In addition, the electrical assembly has a second wiring carrier, which is arranged opposite the first wiring carrier on the upper-side electrical contact of the electronic switching element. According to the invention, the first and the second wiring carrier are each formed at least partially, i.e. at least in regions, from a permanently elastic, electrically insulating, thermally conductive material.

[0010] By electrically contacting the switching element on both sides, it is advantageously possible to implement particularly complex functionalities of the overall electrical component and, in particular, of the electronic switching element. The electrical contacting on both sides can also offer a particularly high degree of flexibility in implementing or realizing the respective desired functionalities. Especially for power electronic components, the respective cross-sectional areas of the conductors cannot be reduced arbitrarily, so that more conductors or connections can be routed to the electronic switching element by means of the electrical contacting on both sides.A further advantage of the double-sided electrical contact and the permanently elastic, thermally conductive material regions or layers of the respective wiring carriers arranged on both sides, i.e., below the underside and above the top of the electronic switching element, is that heat generated during operation of the electrical assembly can be dissipated from the electronic switching element in both opposite directions. The proposed design can therefore offer improved temperature and heat management, thus enabling higher electrical and / or thermal load capacity and / or power density within the electrical assembly or within the electronic switching element without causing damage.

[0011] To overcome the problems and challenges mentioned above, the solution proposed here utilizes the integration of several functions or functionalities into the wiring carriers. The elasticity of the wiring carriers—or the corresponding permanently elastic material regions of the wiring carriers—allows them to absorb compressive forces applied during a manufacturing, assembly, or joining process of the electrical assembly, in particular those applied at least substantially perpendicular to the underside and top of the electronic switching element, without damage. This enables a height-adaptive approach of the joining partners, i.e., the components, of the electrical assembly. In other words, the elasticity of the wiring carriers can be utilized for tolerance compensation, i.e., maintaining a specified final tolerance of the entire electrical assembly.A corresponding tolerance chain of the electrical assembly is advantageously significantly relaxed by the flexible final dimension of the electrical assembly due to the elasticity of the wiring carriers, and can therefore be maintained with less effort.

[0012] In addition to this tolerance compensation, the elasticity of the wiring carriers offers the possibility and advantage of compensating for thermal expansion differences, i.e., different thermal expansion coefficients and / or different temperatures, of the joining partners of the electrical assembly, particularly under alternating electrical and / or thermal loads. Such expansion differences can have a damaging effect on conventional assemblies or structures, i.e., lead to damage or accelerated aging of the respective assembly or structure or individual components. The elasticity of the wiring carriers prevents or reduces the buildup of mechanical stress, particularly thermally induced stress, within the electrical assembly.

[0013] Particularly advantageously, the respective permanently elastic material of the wiring carriers can offer mechanical flexibility or elasticity in different spatial directions. This means that the permanently elastic material can be deformed without damage not only in a first direction perpendicular to the underside and the top side or the corresponding surfaces or a corresponding main extension plane of the electronic switching element, but also at least in a second direction, which can preferably extend perpendicular to the first direction. In other words, the respective permanently elastic material can also absorb deformations or expansion differences in or parallel to a connection plane between two components of the electrical assembly without damage.This connection plane can, for example, be arranged parallel to the top and bottom of the main extension plane of the electronic switching element.

[0014] The electrical assembly can be a stack of components, i.e., have a stack-like structure or a stack-like design. The individual components can, in particular, have a planar extension, i.e., a layer-like shape or form, i.e., each form a layer or part of a layer of the stack or electrical assembly. The permanently elastic material can then be deformed without damage both perpendicular to the individual layers, i.e., in the stacking direction, and parallel to the layers or plies, i.e., at least substantially perpendicular to the stacking direction.For example, an external cooling element, i.e. one arranged on the outside of the electrical assembly or forming an outer side of the electrical assembly, can expand more transversely to the stacking direction during operation of the electrical assembly, i.e. have a greater relative change in length, than, for example, the contact located further inside or the electronic switching element also arranged further inside.

[0015] These expansion differences are absorbed and compensated for by the permanently elastic material in between, so that damage, such as tearing, of the cooling element, the contact, the switching element or corresponding connections can be avoided.

[0016] The present invention therefore demonstrates how even complex electrical assemblies can be realized with improved thermomechanical behavior and higher electrical and / or thermal load capacity, while at the same time, with relatively little effort compared to known methods, specified tolerances for a size, in particular a height, of the electrical assembly can be maintained. By using the permanently elastic material on both sides, particularly high-performance materials with their respective individual functionality can advantageously be used for other components of the electrical assembly, even if these have significantly different thermomechanical behavior or thermal expansion coefficients. This avoids previously necessary compromises in material selection and achieves an overall improved performance of the electrical assembly.

[0017] For the purposes of the present invention, an electrical or electronic assembly can be understood as a structural and / or functional combination or as a structural and / or functional unit comprising integrated and / or discrete, active and / or passive components or elements. These components or elements can be electrically connected to one another by an electrical wiring network. The permanently elastic, electrically insulating, thermally conductive material does not have to play a part in an electrical or electronic signal or data processing or forwarding function of the electrical assembly. It can, for example, serve as a carrier for at least part of the electrical wiring network, an electrical contact and / or at least one other component of the electrical assembly.

[0018] The permanently elastic material can preferably form a partial region, in particular a layer, of the respective wiring carrier. A remainder or remaining region of the respective wiring carrier can thus be formed from a different material. This can advantageously improve the mechanical stability, for example, the flexural rigidity, of the electrical assembly without sacrificing the advantages achieved by using the permanently elastic material.

[0019] The permanently elastic, electrically insulating, and thermally highly conductive material can be selected from known materials with these properties—in individual cases, for example, depending on individual requirements. The present invention is therefore not directed to a specific composition of this or such a material, since suitable materials are generally known.

[0020] Components of the present electrical assembly include, for example, the electronic switching element and the wiring carriers. The electrical contact or a corresponding electrical contact layer can also be considered a component. Furthermore, the electrical assembly can include other components, such as cooling elements, mechanical supports, sensors, and the like.

[0021] According to the invention, the electronic switching element has at least one power semiconductor. In other words, the electronic switching element can comprise one or more power electronics chips. The present invention can be used particularly advantageously for electrical assemblies that have power electronic components or elements or that combine or integrate power electronics and logic or computing components. The use of power electronic components results in increased power loss within such an assembly, which makes effective management of the thermomechanical behavior of the assembly particularly important. The relatively high temperatures caused by this relatively high power loss generally have a detrimental effect on logic circuits or computing devices within the assembly.Nevertheless, increased spatial packing density—including of different components—is increasingly sought, for example, to advance miniaturization and reduce signal propagation times. Practical applications in which the present invention can be advantageously used include photovoltaic systems, inverters, control and power distribution systems for electric motors, and the like.

[0022] In a further advantageous embodiment of the present invention, the permanently elastic material of the first and / or second wiring carrier is pressed onto a metallic carrier. The permanently elastic material can thus be connected, in particular, to the respective metallic carrier in a force-locking manner. In particular, a material connection can be dispensed with. Pressing means that a mechanical and thermal, in particular heat-conducting, contact between the permanently elastic material and the respective metallic carrier is established or ensured by a force acting perpendicular to a connecting or contact surface or plane between the permanently elastic material and the respective metallic carrier.The force can be exerted evenly over the entire surface of this contact plane or predetermined contact areas, i.e. parts of the total contact surface, can be pressed together in a force-locking manner.

[0023] Due to the elasticity, i.e., the deformability, of the permanently elastic material, optimal contact between the permanently elastic material and the metallic substrate can be established and ensured even without a material bond, since, for example, unevenness or structural defects in the respective metallic substrate can be filled or compensated for by the permanently elastic material. Since the permanently elastic material is also thermally conductive, waste heat generated in the electrical assembly can be transferred or dissipated to the metallic substrate particularly effectively and efficiently through the permanently elastic material.

[0024] Due to its particularly good thermal conductivity, the metallic substrate can then distribute, transmit, or dissipate this heat particularly effectively and efficiently. At the same time, the elasticity of the permanently elastic material prevents any potential mis-expansion, i.e., a damaging difference between the relative and / or absolute thermally induced length changes of the respective metallic substrate on the one hand and another component of the electrical assembly arranged on another, particularly opposite, side of the permanently elastic material.

[0025] Due to the elasticity of the permanently elastic material, optimal heat flow, i.e. effective and efficient dissipation of waste heat from the electrical assembly, can be achieved even under significant thermomechanical load, since mechanical stress can be compensated and the best possible thermal and mechanical contact can be maintained.

[0026] The metallic carrier can offer or improve mechanical stability, for example against bending, as well as protection against damage caused by mechanical effects on the electrical assembly. For this purpose, the metallic carrier can be arranged further outwards with respect to a central or mid-plane of the electrical assembly, i.e. further away from a center point of the electrical assembly, than the permanently elastic material. In other words, the permanently elastic material can be arranged on the inside of the respective metallic carrier. The metallic carrier can be part of the respective first or second wiring carrier. In other words, the respective permanently elastic material and the respective metallic carrier together can form the respective wiring carrier.

[0027] Of course, the respective wiring carrier can also comprise additional components, elements, or parts. If the respective metallic carrier is part of the respective wiring carrier, a particularly high functional density can be advantageously achieved, since the wiring carrier, constructed in this way from several different areas or materials, can combine or fulfill multiple functions in one component. This advantageously eliminates the need for a corresponding additional component for at least one of these functionalities.

[0028] In order to achieve a particularly high functional density of the electrical assembly, the metallic carrier can, for example, assume a cooling function. For this purpose, a further advantageous embodiment of the present invention provides that the respective metallic carrier is designed as a cooling element for cooling the electrical assembly. In other words, the functionalities of a wiring carrier and a cooling element can be combined or unified in a single component by the wiring carrier according to the invention. The fact that the metallic carrier is designed as a cooling element can, for example, mean that the respective metallic carrier forms an outer side or surface of the electrical assembly, such that it can radiate or dissipate heat to the respective surroundings of the electrical assembly.For this purpose, the outer or upper side of the respective metallic carrier facing away from the permanently elastic material can, for example, have cooling fins or be shaped in another way in order to achieve an enlarged surface and thus an increased heat dissipation capacity.

[0029] Likewise, the metallic carrier can, for example, be designed to be connected to a cooling circuit or a coolant circuit. For this purpose, the metallic carrier can, for example, have corresponding receptacles or fastening elements by means of which it can be connected to an external cooling system or cooling device or can be thermally connected to an external cooling system or cooling device. Due to its thermal conductivity and its mechanical stability and resilience, the metallic carrier is particularly suitable for this purpose. Likewise, the metallic carrier can, for example, have a bore or a channel through which a coolant or cooling medium can flow through the metallic carrier. This makes it possible to achieve particularly efficient heat dissipation.

[0030] According to the present invention, in all connection levels of the electrical assembly in which at least two components are connected to one another, the respective at least two components are connected to one another in a force-fitting manner, without the need for a material-to-material connection. In other words, the components of the electrical assembly can be separated from one another non-destructively by dispensing with material-to-material connections. By producing and holding the electrical assembly together using force-fitting assembly or joining measures or methods, an improved thermomechanical, and ultimately also electrical, load capacity of the electrical assembly as a whole can advantageously be achieved. This is the case because the force-fitting joins or connections can enable the individual components to slide against one another.Thus, the individual components, which may in particular have different thermal expansion coefficients and / or different temperatures, can expand or contract independently of one another without this leading to damaging mechanical stress or corresponding mechanical stresses within the electrical assembly.

[0031] To ensure the functionality of the electrical assembly despite the lack of a material-to-material joining, electrical and / or thermal contacts can be realized by force-fitting or pressing together suitable contact surfaces or contact areas of the respective components. This can be achieved permanently, for example, by one or more spring elements, one or more clamps, one or more screw connections, and / or the like. These spring elements, clamps, and / or screw connections or the like can therefore be part(s) of the electrical assembly.Examples of connection levels in this sense can include a level, i.e. a boundary or connecting surface, in which a heat sink or cooling element is connected to a component of the electrical assembly located further inside, as well as the level in which the electrical switching element is electrically and / or thermally contacted on or at its top or bottom.

[0032] In addition to the force-locking connection(s), the electrical assembly may have one or more form-locking connections. This can, for example, limit the displacement of two components relative to each other and / or the movement of one or more components within the electrical assembly in order to permanently maintain or ensure the specified structure and functionality of the electrical assembly.

[0033] In a further advantageous embodiment of the present invention, the permanently elastic material of the first and / or second wiring carrier forms a layer that directly abuts the respective electrical contact of the electronic switching element. The permanently elastic material of the first wiring carrier can thus, for example, support or accommodate an electrical contact layer or an electrical line by means of which the underside of the electronic switching element is electrically contacted. Similarly, the permanently elastic material of the second wiring carrier can support or accommodate an electrical contact layer or an electrical line by means of which the top side of the electronic switching element is contacted.

[0034] The permanently elastic material of the wiring carriers can be a dielectric that at least partially surrounds the electronic switching element on the underside and / or on the top side, thus forming a dielectric layer or layer within the electrical assembly.

[0035] The arrangement of the permanently elastic material directly at the electrical contact of the electronic switching element, i.e. at a minimal distance from it, is particularly advantageous for improving the thermomechanical behavior of the electrical assembly, since the waste heat to be dissipated can arise in the electronic switching element. The elasticity of the permanently elastic material advantageously allows a maximum contact area for heat dissipation to be achieved with minimal manufacturing effort, since the permanently elastic material adapts itself automatically to local shapes when the electrical assembly is joined. The permanently elastic material therefore advantageously offers particularly good formability, which advantageously leads to particularly low thermal resistance to and from the permanently elastic material.

[0036] On the other hand, maximum temperatures, temperature fluctuations, and / or temperature gradients can occur at this point. By arranging the permanently elastic material directly at the electrical contact of the electronic switching element—and possibly also at least partially at the electronic switching element itself—thermomechanical effects, such as potentially damaging misalignments in conventional designs, can be particularly advantageously absorbed or compensated.

[0037] While known conventional electrical assemblies often have an asymmetrical design, the present invention advantageously allows a symmetrical design or structure of the electrical assembly to be realized. By arranging the same permanently elastic material both on or at the bottom and on or at the top of the electronic switching element, particularly uniform heat dissipation from the electronic switching element can be achieved. Such symmetrical cooling of the electrical switching element can advantageously prevent the development of a temperature gradient or thermomechanical stress within the electronic switching element.This cannot be ensured in conventional known electrical assemblies in which, for example, a filling material or a potting compound is arranged on one side of the electronic switching element, since the different materials on the top and bottom of the electronic switching element usually have different thermal conductivities and heat capacities.

[0038] In a further advantageous embodiment of the present invention, the permanently elastic material of the first and / or second wiring carrier contains a polysiloxane and another component, in particular metal oxide particles and / or ceramic particles. This represents a proven possibility for creating a permanently elastic material with the desired thermal, mechanical, and electrical properties.

[0039] In addition to the electrical assembly, a further aspect of the present invention is a method for producing an electrical assembly. In the method according to the invention, an external compressive force is exerted on an external first and an external second wiring carrier of the assembly opposite the first wiring carrier to join the assembly. The wiring carriers are each formed at least partially from a permanently elastic, electrically insulating, thermally conductive material. At least one electronic switching element is arranged between the wiring carriers. By means of the compressive force, thermal and / or electrical contacts of at least the at least one switching element are produced within the electrical assembly on an underside facing the first wiring carrier and an upper side of the switching element facing the second wiring carrier, without the need for material-to-material connections.This means that the switching element and the wiring carriers are brought into direct or indirect contact.

[0040] In an advantageous embodiment of the method according to the invention, the components of the assembly are toleranced such that, before the compressive force is applied, a minimum dimension of the assembly perpendicular to a connecting plane between the at least one electronic switching element and the wiring carriers is at least as large as a target or maximum dimension of the finished, i.e., the fully assembled, i.e., fully manufactured, assembly. The compressive force compresses and / or deforms the permanently elastic material of the first and / or second wiring carrier, thereby bringing the assembly to the target dimension.In other words, by tolerancing the components, it can be ensured that the electrical assembly has a specified minimum thickness before the compressive force is applied, i.e., before the assembly is finally joined, despite the tolerance chain created by the multitude of different components within the electrical assembly. A tolerance band is then provided by the elasticity or deformability of the permanently elastic material. This tolerance band can then be fully exploited during joining, i.e., during assembly production, by varying or adjusting the external compressive force.

[0041] The properties and developments of the assembly according to the invention described above and below, as well as the corresponding advantages, are transferable mutatis mutandis to the method according to the invention and / or to components and devices used or usable for carrying out the method according to the invention, and vice versa. Thus, the invention also includes developments of the assembly according to the invention and the method according to the invention that have configurations not explicitly described here in the respective combination.

[0042] Further features, details, and advantages of the present invention will become apparent from the following description of preferred embodiments and from the drawing. The single figure shows a schematic sectional side view of an exemplary electrical assembly with two electronic switching elements contacted on both sides, which are arranged between two wiring carriers, in particular between two layers of a permanently elastic, electrically insulating, thermally conductive material.

[0043] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0044] The single figure shows an electrical assembly 1 in a schematic and sectional side view. In this case, the electrical assembly 1 comprises two wiring carriers 2, each arranged externally. These are a lower wiring carrier 3 and an upper wiring carrier 4. Two power semiconductors 5 are arranged between the wiring carriers 2 as an electronic switching element.

[0045] With the increasing desire to increase the number and density of functions and functionalities, coupled with the simultaneous miniaturization and performance enhancement of electrical and electronic assemblies, problems arise in manufacturing and thermomechanical behavior that cannot be addressed with conventional solutions, or can only be addressed with compromises. Conventional solutions essentially aim to control the respective tolerance chain through narrowly specified and sometimes uneconomically achievable individual tolerances of the individual design or component elements of the respective assembly, and thus of the individual links in the tolerance chain. In addition, compensation measures, such as adaptive solder deposition, are sometimes used.Damage caused by different thermal expansion coefficients of the components should be minimized through geometric and material optimization of the assemblies or structures. However, today's technical and economic limitations are being encountered due to the choice of materials, the availability of materials, and their use in the manufacture of the respective assemblies.

[0046] In this case, the wiring carriers 2 each have a permanently elastic layer 6. The respective permanently elastic layer 6 is arranged on the inside of the wiring carriers 2, i.e., on a side facing the power semiconductors 5. The permanently elastic layers 6 are made of a permanently elastic, electrically insulating, yet thermally highly conductive material. Such a material can be formed, for example, from a polysiloxane and a ceramic filler or from a polysiloxane and aluminum oxide particles. A suitable material is known, for example, under the brand name Keratherm.

[0047] The fact that the permanently elastic layers 6 or their material is thermally highly conductive can mean, for example, that the respective permanently elastic layer 6 or its material has a thermal conductivity of at least 2 W / (m·K) and preferably of at least 5 W / (m·K).

[0048] On the inside of the permanently elastic layers 6, electrical contacts of the power semiconductors 5 are arranged between these and the power semiconductors 5. These contacts are a lower contact 7 between the lower wiring carrier 3 and the power semiconductors 5 and an upper contact 8 between the upper wiring carrier 4 and the power semiconductors 5. The contacts 7, 8 can, for example, be copper layers applied in a conventional planar process.

[0049] In the present example, the components of the electrical assembly 1 are at least the wiring carriers 2, the permanently elastic layers 6, and the power semiconductors 5. The electrical contacts 7, 8 can also be considered components, as they can be separate, specific layers. Preferably, the components of the electrical assembly 1 are not bonded to one another. Rather, the cohesion of the electrical assembly 1 is achieved through force-fit connections.

[0050] To join the electrical assembly 1, a joining force 9, the direction of which is schematically illustrated here by arrows, is exerted on one or both of the wiring carriers 2. The joining force 9 can compress the electrical assembly as a whole, and in particular the material of the permanently elastic layers 6. This enables tolerance compensation during production in a simple manner in order to bring an actual dimension of the electrical assembly 1, which existed before the joining force 9 was applied, to a predetermined target dimension in the direction of the joining force 9. For this purpose, the joining force can be controlled or adjusted individually to suit the respective electrical assembly 1. For this purpose, it may be possible to measure or monitor the actual dimension of the electrical assembly 1 before and / or during the application of the joining force 9.Advantageously, the elasticity of the permanently elastic layers 6 distributes the joining force 9 particularly evenly, whereby mechanical damage, for example to the contacts 7, 8 or the power semiconductors 5, can be avoided.

[0051] Both the elasticity of the permanently elastic layers 6 and the omission of material connections between the components, i.e., in the connection levels of the electrical assembly 1, prevent or at least reduce the buildup of thermally induced mechanical stresses during operation of the electrical assembly 1. Such thermomechanical stresses can occur, in particular, when different, particularly neighboring, components have different coefficients of thermal expansion (CTE), and can then lead to incorrect expansion, i.e., changes in the length of the components of varying degrees, which can ultimately damage the electrical assembly 1.

[0052] Such misalignments due to different thermal expansion coefficients (CTE mismatch) can be compensated for by the permanently elastic layers 6. For example, a respective region of the wiring carrier 2 facing away from the power semiconductors 5 and the permanently elastic layers 6 can be formed from a metallic material, for example aluminum. These regions can then serve as cooling elements for cooling the electrical assembly 1. However, if these metallic or aluminum regions heat up during operation of the electrical assembly 1, they expand, in particular more than, for example, the power semiconductors 5, which can be formed predominantly from silicon and silicon oxides.The greater thermal expansion or change in length of the metallic or aluminum areas of the wiring carriers 2 then leads to a deformation or to a flexing of the permanently elastic layers 6 and is not passed on to the power semiconductors 5, or at least not to the full extent.

[0053] By omitting material connections in the respective connection planes, the individual components can also slide along or against each other in directions extending within the respective connection plane or parallel thereto. The connection planes of the electrical assembly 1 extend perpendicular to a plane of the drawing between each two adjacent components. This sliding, or independent expansion or contraction of the components parallel to the connection planes, serves to compensate for thermomechanical stresses and is indicated schematically here by a double arrow 10.

[0054] The representation of the electrical assembly 1 shown here is merely an exemplary structure. Of course, other, even more complex, structures and arrangements are also possible. For example, additional layers or regions made of the permanently elastic material of the permanently elastic layers 6 can be provided to absorb any incorrect expansion that would otherwise occur between other components. List of reference symbols

[0055] 1Electrical assembly 2Wiring carrier 3Lower wiring carrier 4Upper wiring carrier 5Power semiconductor 6Permanently elastic layer 7Lower contact 8Upper contact 9Joining force 10Double arrow

Claims

1. Electrical assembly (1), having an electronic switching element (5), which is electrically contacted (7) on its underside and is arranged on a flexible first wiring support (3) of the electrical assembly (1) and has at least one power semiconductor (5), wherein - the electronic switching element (5) is additionally electrically contacted (8) on an upper side lying opposite the underside, - the electrical assembly (1) has a second wiring support (4), which is arranged lying opposite the first wiring support (3) on the upper side electrical contacting area (8) of the electronic switching element (5), - the first and the second wiring supports (3, 4) are each formed at least in part from a permanently elastic, electrically insulating, thermally conductive material (6), characterised in that - in all connection planes of the electrical assembly (1), in which in each case at least two components (2, 3, 4, 5, 6, 7, 8) are connected to one another, the respective components (2, 3, 4, 5, 6, 7, 8) are connected to each other by a force fit while foregoing an integrally bonded connection.

2. Electrical assembly (1) according to one of the preceding claims, characterised in that the permanently elastic material (6) of the first and / or of the second wiring support (3, 4) is pressed onto a metallic support.

3. Electrical assembly (1) according to claim 2, characterised in that the respective metallic support is embodied as a cooling element for cooling the electrical assembly (1).

4. Electrical assembly (1) according to one of the preceding claims, characterised in that the permanently elastic material (6) of the first and / or the second wiring support (2, 3, 4) contains a polysiloxane and a further component, in particular metal oxide particles and / or ceramic particles.

5. Method for producing an electrical assembly (1), in which - to join the assembly (1) together, an external compressive force (9) is exerted on a first outer wiring support (3, 4) of the assembly (1) and on a second outer wiring support (3, 4) lying opposite the first one, which are each formed at least in part from a permanently elastic, electrically insulating, thermally conductive material (6), wherein at least one electronic switching element (5) is arranged between the wiring supports (3, 4), and - through the compressive force (9) within the assembly (1), while foregoing integrally bonded connections, thermal and / or electrical contacting at least of the at least one switching element (5) is established on an underside facing towards the first wiring support (3) and on an upper side of the switching element (5) facing towards the second wiring support (4).

6. Method according to claim 5, characterised in that - the components (2, 3, 4, 5, 6, 7, 8) of the assembly (1) are provided with tolerances so that, before the compressive force (9) is exerted, a minimum dimension of the assembly (1) at right angles to a connection plane between the at least one electronic switching element (5) and the wiring supports (2, 3, 4) is at least as large as a required or maximum dimension of the completed assembly (1), and - through the compressive force (9) the permanently elastic material (6) of the first and / or of the second wiring support (2, 3, 4) is deformed and the assembly (1) is thereby set to the required dimension.