Power module and method for producing such a power module

Abstract

The invention relates to a power module (10) comprising a heat sink element (1), the power module comprising - a ceramic element (25), - a component metallisation (20), and - the heat sink element (1), wherein the ceramic element (25), the component metallisation (20) and the heat sink element (1) each extend substantially along a plane running parallel to a main extension plane (HSE) and are arranged one above the other in a stacking direction (S) running perpendicular to the main extension plane (HSE), wherein the ceramic element (25) is arranged between the component metallisation (20) and the heat sink element (25), wherein the component metallisation (20) has a first thickness (D1) measured in the stacking direction (S), and the heat sink element (1) has a second thickness (D2) measured in the stacking direction (S), wherein the ratio of the first thickness (D1) to the second thickness (D2) is less than 0.4, preferably less than 0.3, and particularly preferably less than 0.2, wherein the heat sink element (1) is designed such that the flexural deformation of the power module (10) is five times smaller, preferably eight times smaller, and particularly preferably ten times smaller than that of a reference power module with dimensions corresponding to the power module (10), wherein the reference power module has a solid heat sink element (1).

Description

[0001] Power module and method for producing such a power module

[0002] The present invention relates to power modules and a method for producing such a power module.

[0003] Power modules are well known in the art and offer the possibility of creating circuits or electrical connections between electronic or electrical components via appropriate connection surfaces and conductor tracks. It has proven particularly advantageous to use ceramic as an insulating element on which the individual metal sections of a component metallization are applied. Such ceramics exhibit comparatively high insulation strength and are particularly temperature-resistant. With the increasing demands on such power modules and the associated heat generation, increasing challenges are being placed on the corresponding cooling systems, which are designed to ensure efficient heat dissipation.

[0004] A classic approach to providing a heat sink element is to connect a cooling structure with cooling fins to the backside metallization of a metal-ceramic substrate. This arrangement of the corresponding cooling fins guides a cooling medium, particularly a cooling liquid, to ensure appropriate heat dissipation. It is necessary to implement the connection via backside metallization, as this backside metallization is essential for the bonding process of a metal layer to a ceramic element. Otherwise, particularly with a one-sided bond between the metal layer and the ceramic element, the different expansion coefficients and the associated thermomechanical stresses would cause the metal-ceramic substrate to sag when the temperature changes, for example, during cooling after bonding.As a further development of this comparatively simple fin structure, the teaching of DE 10 2013 109 246 B4 proposes that a large number of microchannels be embedded in a heat sink structure for the surface cooling of a power module. Essentially loop-shaped cooling channels guide the cooling medium as close as possible to the area to be cooled in the power module and simultaneously guide it away from a corresponding cooling surface. Preferably, many such cooling channels are supplied with the cooling medium together via a common distribution structure.

[0005] In particular, loop-shaped cooling channels are provided as microchannels, which are of identical design and arranged parallel to each other. This advantageously makes it possible to deliver the cooling medium to the surface to be cooled in a particularly directed and targeted manner, and in particular, it makes it possible to ensure the most homogeneously distributed cooling on the cooling side of the heat sink element.

[0006] Furthermore, it is common practice in the prior art for the metal-ceramic substrates intended as power modules to be provided to a customer, who in turn connects the heat sink to the metal-ceramic substrate, particularly to the backside metallization of the metal-ceramic substrate. Separating these two steps often makes it impossible to adapt the heat sink to the metal-ceramic substrate as efficiently as possible, as the corresponding manufacturing steps are separated from each other.

[0007] The present invention therefore has the object, based on the prior art, of simplifying a manufacturing process for coolable power modules and, in particular, of improving the cooling efficiency and compactness of the power modules.

[0008] The present invention solves this problem with a power module according to claim 1 and a method for producing such a power module according to claim 10. The further description, the figures and the subclaims contain further non-limiting embodiments of the invention.

[0009] According to a first aspect, a power module with a heat sink element is provided, comprising a ceramic element, a component metallization and the heat sink element, wherein the ceramic element, the component metallization and the heat sink element extend substantially along a plane running parallel to a main extension plane and are arranged one above the other in a stacking direction running perpendicular to the main extension plane, wherein the ceramic element is arranged between the component metallization and the heat sink element, wherein the component metallization has a first thickness measured in the stacking direction and the heat sink element has a second thickness measured in the stacking direction, wherein a ratio between the first thickness and the second thickness is less than 0.4, preferably less than 0.3 and particularly preferably less than 0.2, wherein the heat sink element, in particular by hollow regions in the heat sink element,In particular, by a targeted arrangement of hollow areas in the heat sink element, and / or in particular by a targeted mass distribution within the heat sink element, it is designed such that deflection of the power module is five times smaller, preferably eight times smaller, and particularly preferably ten times smaller than for a reference power module with dimensions corresponding to the power module, wherein the reference power module has a solidly formed heat sink element. In particular, the reference power module has a second thickness corresponding to the second thickness of the power module. The reference power module differs essentially only from the power module in that it is designed as a solid, cavity-free metal layer with the second thickness of the power module.

[0010] In contrast to the procedures known from the prior art, it is provided that the shape of the heat sink element, in particular an internal shape of the heat sink element, is used to compensate for the thermomechanical stress acting on the rear and front sides of the ceramic element throughout the power module. This deviates in particular from the approach customary in the prior art, in which the heat sink element was designed independently of the power module and simply bonded to a rear-side metallization following the manufacture of the metal-ceramic substrate. This enables, in particular, the simultaneous bonding of the heat sink element to the ceramic element, preferably during a common bonding process. This avoids an additional work step, namely the subsequent bonding of the heat sink element.However, this can only be meaningfully achieved if the heat sink element is designed such that the deflection is reduced compared to the reference power module, ie, the power module with the same geometric design but a solid heat sink element. A person skilled in the art understands a solid heat sink element to mean, in particular, a hollow-region-free heat sink element, ie, a substantially structureless metal layer or metal block.

[0011] It has therefore been found that, despite significantly different thicknesses, i.e. a second thickness of the heat sink element and a first thickness of the component metallization with the specified ratio, it is entirely possible to ensure a power module whose deflection does not impair the functionality of the power module, in particular does not restrict it or makes its use possible. Deflection is understood in particular as the deviation from a completely flat plane. Typically, deflection is a type of curvature, so that deflection can preferably be assumed to be the angle that forms between a plane that runs tangentially through a vertex of the curvature and a point that deviates as much as possible from or is spaced from the course of the planar plane that runs through the vertex.This angle can, for example, be used as a scale to determine the respective deflection. The angles for the reference power module and the power module must be determined at the same distance from the vertex.

[0012] For example, the first thickness assumes a value between 0.1 mm and 4 mm, preferably between 0.1 and 2 mm and particularly preferably between 0.2 and 0.8 mm and / or the second thickness assumes a value between 0.5 mm and 6 mm, preferably between 1.0 and 5 mm and particularly preferably between 1.5 and 4 or even 2 and 3.5 mm.

[0013] The heat sink element can preferably be formed from a metal layer or a plurality of metal layers. However, it is also conceivable that a composite structure is formed in which metal and / or ceramic alternately determine the shape of the heat sink. A heat sink element made of ceramic layers is also conceivable. The individual layers can be made of metal and / or a ceramic material. Materials conceivable for a metal layer include copper, aluminum, molybdenum, tungsten, nickel and / or their alloys such as CuZr, AlSi or AlMgSi, as well as laminates such as CuW, CuMo, CuAl and / or AlCu or MMC (metal matrix composite), such as CuW, CuM or AlSiC. Preferably, a ceramic layer or the ceramic element comprises Al2O3, SiA4N4, AlN5, an HPSX ceramic (i.e.a ceramic with an Al2O3 matrix containing an x-percent ZrCh content, for example Al2O3 with 9% ZrCh = HPS9 or Al2O3 with 25% ZrC>2 = HPS25), SiC, BeO, MgO, high-density MgO (> 90% of the theoretical density), TSZ (tetragonally stabilized zirconium oxide) as the material for the ceramic. It is also conceivable for the ceramic layer to be designed as a composite or hybrid ceramic, in which, in order to combine various desired properties, several ceramic layers, each differing in terms of their material composition, are arranged one above the other and combined to form an insulating element. In particular, it is necessary that a certain porosity is ensured in the heat sink element by means of appropriate cavities, so that a comparable mass distribution is provided on the top side of the ceramic element and the back side of the ceramic element in order to compensate for any deflection in a reasonable manner.Such compensation is only possible if the heat sink element is designed to be correspondingly delicate and fine. Preferably, the ceramic element, especially if it is provided as a component of the heat sink element, has a thermal conductivity greater than 80 W / mK, preferably greater than 100 W / mK, and particularly preferably greater than 120 W / mK. This allows for the advantageous thermal resistance required for effective heat dissipation to be achieved.

[0014] To reduce deflection, the heat sink element preferably has a plurality of three-dimensionally arranged web elements which together form cooling channels. These are assembled in such a way that they form corresponding cavities which exert a corresponding influence on the deflection. The web elements preferably have a web width which is less than 250 μm, preferably less than 200 μm and particularly preferably less than 150 μm. It has been found to be advantageous that such thin web widths enable plastic deformation during cooling in the bonding process. This contributes to reducing mechanical stress and has a positive effect on the extent of deflection. In particular, the web elements are designed in such a way that they form wall structures or partitions, in particular comparatively thin wall structures or partitions which, for example, separate a feed section and a discharge section from one another.These can be plastically deformed relatively easily during cooling and can thus contribute to compensation to the desired extent. Preferably, the web elements have a cross-section along a plane perpendicular to a preferred direction that is rectangular, square, and / or round, and / or occupies an area smaller than 0.08 mm. 2 , preferably less than 0.05 mm 2 and particularly preferably less than 0.038 mm 2 .

[0015] Furthermore, it is preferably provided that the heat sink element, as a body, defines a first volume through its outer circumference, and the hollow regions in the heat sink element occupy a second volume (determined, for example, as the complete filling of all cooling channels with a liquid), wherein a ratio of the second volume to the first volume assumes a value that is greater than 0.5, preferably greater than 0.6, and particularly preferably greater than 0.7. It has been found that with an increasing proportion of hollow regions in the heat sink element, the compensation of thermomechanical stresses in the heat sink element can be improved.

[0016] The power module is preferably designed as a metal-ceramic substrate, in which the at least one metal layer bonded to the ceramic element is structured in the manufactured state. For example, it is provided that, after the bonding step, structuring is also carried out, for example by lasering, etching, and / or mechanical processing, to create conductor tracks and / or connections for electrical or electronic components.

[0017] In particular, it is provided that the heat sink element is directly bonded to the ceramic element. Such a direct bond can be recognized in the manufactured metal-ceramic substrate, for example, by the fact that a homogeneous grain size distribution results along the length of the heat sink element, in particular from a first end face to the second end face. In other words: it is not recognizable that a different grain size is realized in a section of the heat sink element directly adjacent to the ceramic element than in the remaining part of the heat sink element. This makes it clear, particularly from the manufactured metal-ceramic substrate, that the heat sink element as such was immediately and directly bonded to the ceramic element, in particular to its rear side.Such a direct connection proves to be particularly advantageous because it eliminates the need for a complex intermediate step in which first the backside metallization and then the heat sink must be connected to the backside metallization. Preferably, the component metallization has a first mass and the heat sink element has a second mass, wherein the second mass deviates from the first mass by only less than 160%, preferably less than 120%, and particularly preferably less than 80%. Such a mass distribution proves to be particularly advantageous in counteracting sagging. It can be seen that, despite the significant differences in thickness, the difference between the first mass and the second mass is comparatively small. In addition, the entire power module is particularly lightweight.This is preferably combined with a corresponding alignment of the individual wall structures in the heat sink element, for example, to create appropriate leverage. This cannot be guaranteed with the conventional approach.

[0018] Furthermore, it is also conceivable that a grain size influences the thermomechanical stresses on the front and back of the ceramic element and / or also takes these into account. It is particularly preferred that the component metallization has an average first grain size and the heat sink element has an average second grain size, wherein a ratio of the average first grain size to the average second grain size is less than 0.7, preferably less than 0.5, and particularly preferably less than 0.25. In other words: the component metallization comprises a fine grain, while the heat sink element has a coarse grain. At least a corresponding grain size distribution is taken into account in the design of the heat sink element.

[0019] It is also conceivable that the mass distribution in the heat sink element could be influenced by stacked and interconnected layers exhibiting a web width modulation along a plane parallel to the main extension plane before they are joined together, in order to specifically increase density in certain areas and create a corresponding leverage effect. Furthermore, it is conceivable that deflection could be influenced by strengthening the layers joined together to form the heat sink element.

[0020] It is particularly preferably provided that the ceramic element has a third thickness measured in the stacking direction and that the third thickness assumes a value of up to 500 pm, preferably a value of up to 300 pm and particularly preferably a value of up to 250 pm or even a value of up to 200 pm. This includes the respective limits, i.e. 500 pm, 300 pm, 250 pm and 200 pm. It has been found that it is even possible to design the ceramic elements to be this thin by suitably designing the heat sink element. This would not be possible, for example, if deflection were to be expected for the reference module, because in such cases these comparatively thin ceramic elements could break and the functionality of the power module would be compromised.

[0021] To influence the thermomechanical compensation stress forces, particular consideration is given to the fact that a corresponding leverage effect can also lead to a compensation of the thermomechanical stresses through a corresponding mass distribution on the side of the heat sink element. In this case, the person skilled in the art will particularly draw on his or her experience with the bonding processes and / or, for example, on corresponding simulations that take into account the corresponding material and geometric properties of the heat sink element. In particular, it is provided that the heat sink element is porous, in particular is provided with a plurality of cooling channels. By forming a plurality of cooling channels, it is advantageously possible to ensure a corresponding mass distribution in that the heat sink element has a corresponding plurality of cavities, which reduces the mass without influencing the thickness of the heat sink element.This also makes it possible to provide correspondingly smaller second masses without reducing the thickness of the second heat sink element. The heat sink element preferably has more than 30, preferably more than 90, and particularly preferably more than 150 cooling channels, in particular active cooling channels.

[0022] In particular, cooling channels are embedded in the heat sink element to influence the thermomechanical stress on the back of the ceramic element. Accordingly, it is conceivable, for example, to counteract such deflection by the targeted placement of cooling channels. In particular, the deflection of the power module is reduced by the positioning of the cooling channels.

[0023] Furthermore, it is preferably provided that the component metallization has a first extent running parallel to the main extension plane and the heat sink element has a second extent running parallel to the main extension plane, wherein a ratio of the first extent to the second extent assumes a value that lies between 0.9 and 1, preferably between 0.95 and 1 and particularly preferably between 0.98 and 1. In other words: it is preferably provided that the component metallization and the heat sink element are only marginally offset in a direction running perpendicular to the stacking direction, in particular in order to avoid leverage effects as far as possible. In this case, the first extent and the second extent do not end in alignment with one another as seen in the stacking direction, in order in particular to be able to provide a pullback on the side of the ceramic element that faces the component metallization.It is particularly preferred if the heat sink element is flush with the ceramic element in an outer periphery bounded by a plane running parallel to the main extension plane. In other words, the ceramic element does not protrude relative to the heat sink element in a direction perpendicular to the stacking direction.

[0024] It is preferably provided that the heat sink element has hollow regions which are not intended for guiding the cooling medium, wherein the hollow regions not intended for guiding the cooling medium are preferably a continuation of an arrangement of cooling channels and / or are preferably arranged in the edge region of the heat sink element.

[0025] In particular, it is provided that the heat sink element has hollow regions that are not intended for conducting a cooling medium. In other words, in addition to the cooling channels that conduct a cooling medium during operation, further hollow regions are provided, which preferably serve the exclusive purpose of reducing the second mass and achieving advantageous mass distribution. For example, the hollow regions have the shape of the cooling channels. In other words, the structure or arrangement of cooling channels is continued in the heat sink element without specific cooling channels being provided for the actual conduction of a cooling medium. They form so-called dummy structures that advantageously contribute to mass distribution. Such unused cavities or dummy structures are preferably embedded in an edge region of the heat sink element.

[0026] Preferably, the heat sink element has cooling channels along its second extension parallel to the main extension plane. In particular, cooling channels are also provided in the areas not intended for cooling. For this purpose, the cooling channels are distributed, preferably homogeneously, across the entire second extension of the heat sink element. This applies in particular to the design of a large board. Thus, connecting structures that would connect the individual heat sink sections, intended for the respective individual substrates, to one another in the large board are preferably dispensed with.

[0027] According to a further aspect, a heat sink element is provided that

[0028] - a base body with a first end face, which in the installed state faces a surface to be cooled, and a second end face opposite the first end face, and

[0029] - a cooling channel which is let into the base body between the first end face and the second end face, wherein the cooling channel has a feed section, a deflection section and a discharge section, wherein the cooling channel is designed to form a general flow path to convey a cooling medium in the feed section in the direction of the first end face, to transfer it into the discharge section in the deflection section and to convey it in the direction of the second end face in the discharge section, wherein the feed section has a first flow cross-section dimensioned perpendicular to a flow direction and the deflection section has a second flow cross-section dimensioned perpendicular to the flow direction, wherein a ratio of the second flow cross-section to the first flow cross-section is less than 0.5, preferably less than 0.4 and particularly preferably less than 0.3.

[0030] In contrast to the approaches known from the prior art, the flow cross-section in the deflection area is specifically changed compared to the flow cross-sections in the supply section and the discharge section, in particular it is significantly reduced. This deviates in particular from the approach which aims to maintain the most constant flow velocity possible in the channels. By specifically influencing the flow velocity, it is advantageously possible to reduce the pressure drop for the cooling medium that the cooling medium experiences when passing through the heat sink element. This is crucial for pumps which are used to pump the cooling medium through the heat sink element. In the case of a small pressure drop for the cooling medium between the inlet and outlet, it is advantageously possible to use pumps which have lower performance requirements.

[0031] Preferably, the first flow cross-section and / or the second flow cross-section and / or the third flow cross-section for forming a microchannel takes a value between 0.1 mm 2 and 25 mm 2 preferably between 0.1 mm 2 and 12.5 mm 2 and particularly preferably 0.1 mm 2 and 5 mm 2These are therefore cooling channels that are designed as a microstructure. In other words: It is preferably provided that the channel structures, formed from a large number of channel elements, are microchannel structures that are dimensioned so small that as many individual cooling channels as possible can be arranged next to one another in order to ensure appropriate homogeneity and even supply to the surface to be cooled. In other words: It is preferably provided that the heat sink element comprises a microchannel cooling structure. This differs in particular from fin-like structures, which are comparatively large and provide very large flow cross-sections between individual fins, in particular in a plane running perpendicular to the flow direction.

[0032] In particular, it is provided that a plurality of separate cooling channels, each with a deflection section, supply section, and discharge section, and in particular a cross-flow section, are formed in the heat sink element. The separate cooling channels are preferably arranged adjacent to one another along two linearly independent directions to form a two-dimensional arrangement of deflection regions. The cooling channels are preferably arranged in a repeating pattern. In particular, the cooling channels are arranged parallel to one another along two row directions.

[0033] Preferably, the supply section and / or the discharge section are formed from a plurality of individual layers, i.e., first layers and / or second layers. This advantageously makes it possible for the individual recesses arranged one above the other, which are formed in the layers, to be slightly offset from one another, thereby creating projections that extend into the cooling channel. This can cause additional turbulence in the cooling channel.

[0034] Furthermore, it is provided that a first flow cross-section in the supply section and / or a second flow cross-section in the discharge section, dimensioned perpendicular to the flow direction, deviates from the second flow cross-section in the deflection section by less than 15%, preferably less than 10%, and particularly preferably less than 5% of the second flow cross-section in the deflection section. The flow cross-section is generally dimensioned in a plane perpendicular to the flow direction in the respective section, preferably as an average value if the flow cross-section changes along the flow direction. This advantageously results in a heat sink element in which comparatively large free spaces are realized, thereby reducing the weight of the heat sink element.Furthermore, it is provided that a flow cross-section in the cross-flow section, which is dimensioned perpendicular to the flow direction, deviates from the second flow cross-section of the deflection section by less than 15%, preferably less than 10% and particularly preferably less than 5% of the second flow cross-section in the deflection section.

[0035] It is also conceivable that the deflection section runs essentially straight in a direction parallel to the main extension plane.

[0036] In particular, it is provided that a first opening is formed in the feed section in the second end face. Furthermore, it is provided that a flow cross-section in the first opening, dimensioned perpendicular to the flow direction, deviates from the first flow cross-section of a downstream section of the feed section by less than 15%, preferably less than 10%, and particularly preferably less than 5% of the first flow cross-section in the downstream section of the feed section. The downstream section of the feed section is preferably located between the deflection section and the first opening, in particular centrally between the deflection section and the first opening. This ensures a particularly large volume flow, which can be introduced into the feed section and guided through the cooling channel.

[0037] In particular, it is provided that a second opening is formed in the second end face in the discharge section. Furthermore, it is provided that a flow cross-section in the second opening, dimensioned perpendicular to the flow direction, deviates from the third flow cross-section of an upstream section of the discharge section by less than 15%, preferably less than 10%, and particularly preferably less than 5% of the third flow cross-section in the discharge section. The upstream section of the discharge section is preferably located between the deflection section and the second opening, in particular centrally between the deflection section and the second opening. This ensures a particularly large volume flow that can be guided through the cooling channel. Furthermore, nozzle effects are avoided. The first opening and / or second opening are preferably dimensioned such that the flow cross-sections of the preceding paragraphs are formed.Furthermore, it is provided that several cooling channels, in particular several separate cooling channels, are each connected to a common supply channel via the supply sections. Each deflection section thus has its own supply section. The supply section is thus defined as the area between a supply channel, which is used by several separate cooling channels, and the deflection section. In particular, it is provided that there is exactly one cross-flow section per cooling channel.

[0038] Furthermore, it is preferably provided that the heat sink element is closed on its first end face or is free of a recess or opening. This means that a continuous material layer is provided on the first end face which, in particular with regard to the material composition, corresponds to at least one layer, i.e. first layer, second layer, third layer and / or fourth layer, from which the heat sink element is formed. This ensures a particularly permanent connection, in particular in a critical area that is exposed to strong temperature changes. The deflection section and thus the cooling fluid are therefore not directly adjacent to an object to be cooled. This advantageously prevents damage or impairments from occurring in this interface area. This increases the service life.

[0039] Furthermore, it is conceivable for the first flow cross-section and / or the second flow cross-section and / or the third flow cross-section to have a polygonal shape. Preferably, the first flow cross-section and / or the third flow cross-section has a star-shaped cross-section. Preferably, the second flow cross-section also differs from the first flow cross-section and / or third flow cross-section in terms of its geometric shape and is, for example, rectangular. By changing the geometric shape, for example from a star-shaped shape to a rectangular shape, turbulence is advantageously promoted during the transition from the feed section to the deflection section, which can prove advantageous for heat transfer. Preferably, the first flow cross-section and / or the third flow cross-section has a geometric shape that has more corners than the second flow cross-section.It has been shown that the different geometries allow for a targeted and improved adjustment of thermal resistance and pressure drop. Furthermore, the respective flow directions in the supply section, diversion section, and discharge section are intended to jointly form the general flow pattern. In particular, the flow direction in the supply section directly follows the flow direction in the diversion section. The same applies to the flow direction in the diversion section and discharge section.

[0040] Furthermore, it is provided that the deflection section preferably runs as parallel as possible to the surface to be cooled, in particular to the first end face, in order to ensure appropriate point-like or area-wide cooling. The deflection section can, for example, also be inclined to the main extension plane and / or have a stepped and / or curved profile. The flow cross-section is understood in particular to be the area that results in the respective cooling channel in a plane running perpendicular to the flow direction. It is therefore a surface that is defined here and through which the cooling medium passes.

[0041] Preferably, a plurality of similarly shaped cooling channels is provided, wherein the cooling channel is part of the plurality of similarly shaped cooling channels. Preferably, more than 50 cooling channels, preferably more than 100 cooling channels, and particularly preferably more than 200 cooling channels are provided in the heat sink element. This advantageously makes it possible to ensure cooling on the first end face as homogeneously as possible. It is also conceivable for the plurality of cooling channels to be arranged in clusters in a subsection. Appropriate clustering of the cooling channels makes it possible, for example, to specifically cool those areas in which greater heat development is expected, particularly during operation. This makes it possible to specifically ensure increased cooling in these areas. Another advantage is that a smaller amount of cooling medium needs to be passed through the heat sink element.In principle, it is also conceivable that several multiplicity of identically shaped cooling channels are formed, wherein the respective multiplicity differs in terms of their type, ie has different designs for the feed section, deflection section and / or discharge section.

[0042] Preferably, the plurality of cooling channels run parallel to one another, preferably along a row direction, and particularly preferably are arranged offset parallel to one another. This advantageously makes it possible, with a suitable distribution structure, as is known, for example, from DE 10 2016 125 338, to whose disclosure content explicit reference is made in this regard, to jointly supply the supply sections of adjacent cooling channels or to receive the cooling fluid that emerges jointly, primarily from the discharge sections. In particular, it is provided that several rows of cooling channels arranged next to one another along a row direction are arranged in a direction predetermined by the main extension plane. This results in a regular pattern of cooling channels in the heat sink element.

[0043] It is preferably provided that the discharge region has a third flow cross-section dimensioned perpendicular to the flow direction, wherein a ratio of the third flow cross-section to the second flow cross-section is less than 0.5, preferably less than 0.4 and particularly preferably less than 0.3. In particular, it is provided that the discharge region has a third flow cross-section dimensioned perpendicular to the flow direction, wherein a ratio between the third flow cross-section and the first flow cross-section is less than 0.5, preferably less than 0.4 and particularly preferably less than 0.3. The third flow cross-section can be larger than the second flow cross-section or vice versa. Particularly preferably, the first flow cross-section is substantially identical to the third flow cross-section.In other words, the flow cross-section decreases from the first opening, through which the cooling medium enters the heat sink element, to the deflection section and then increases again towards the second opening, through which the fluid leaves the heat sink element.

[0044] Preferably, the supply section begins in a first opening, in particular set into the second end face, and / or the discharge section opens into a second opening, in particular set into the second end face, the first flow cross-section being defined in the region of the first opening and / or the third flow cross-section being defined in the region of the second opening. Alternatively, it is conceivable that the first opening and / or the second opening is / are not arranged in the second end face, but is introduced from the side, i.e. from a side which connects the first end face and the second end face and, for example, runs substantially along the stacking direction.The formation of the first opening and the second opening on the second end face proves to be advantageous, in particular for distribution structures that are correspondingly connected to the heat sink element in order to ensure the supply and disposal of the cooling medium. It is preferably provided that the supply section and the discharge section run essentially parallel to one another to form a U-shaped course or are inclined to one another at an angle, wherein the angle assumes a value between 0° and 120°, preferably between 0° and 90° and particularly preferably between 0° and 45°. In particular, the U-shaped design makes it possible to realize a cooling channel that has as little lateral extent as possible. This allows as many cooling channels as possible to be arranged one behind the other and next to one another in rows running parallel to one another.In particular, the cooling channels form a two-dimensional arrangement, preferably with a repeating pattern. By slanting them at the angle mentioned above, the flow velocity can be advantageously influenced, for example, and manufacturing tolerances can also be more easily compensated.

[0045] Furthermore, it is preferably provided that the deflection region has an additional profile. For example, the additional profile is a wave-shaped configuration of the channel wall in the deflection region that faces the first end face. This can be achieved, for example, by corresponding recesses or bulges in a metallization or metal layer that forms a cover layer of the heat sink element on the first end face. A protruding, web-shaped additional structure is also conceivable, which, for example, through a bead-like and / or spherical end, also contributes to increasing the heat transfer from the heat sink element to the cooling fluid.

[0046] Furthermore, it is preferably provided that the supply section and / or the discharge section has additional structuring which protrudes into the cooling channel, which in particular increases cooling efficiency, in particular increases or improves the heat transfer from the heat sink element to the cooling liquid or cooling medium.

[0047] It is preferably provided that the first flow cross-section decreases along the flow direction, in particular decreases continuously, and / or the third flow cross-section increases along the flow direction, in particular increases continuously. Furthermore, it is preferably provided that the heat sink element is closed at the first end face. Alternatively, it is conceivable for it to be open at the first end face and for the rear side of the ceramic element to form part of the cooling channel in the connected state. Furthermore, it is preferably provided that a partition wall is formed between a supply section and a discharge section, which partition wall has a width measured parallel to the main extension plane and becomes smaller from the first end face to the second end face. In this way, a corresponding leverage effect can be changed in a targeted manner and, at the same time, account is taken of the fact that, in particular in a first third orin an area immediately adjacent to the first end face, the heat transfer from the heat sink element to the liquid is most efficient.

[0048] It is preferably provided that a distance between the deflection section and the ceramic element is less than 300 pm, preferably less than 200 pm and particularly preferably less than 100 pm. This allows a particularly close arrangement of the deflection section to the ceramic element. This is only possible if a connection via rear-side metallization is dispensed with, in particular if a first thickness of the component metallization is greater than the distance between the deflection section and the ceramic element. An advantage attributable to this direct connection of the heat sink element is the avoidance of heat spreading and the shortening of a heat path to optimize the cooling performance. It is also conceivable for the deflection section to be directly adjacent to the ceramic element. In this case, the heat sink element, which is directly connected to the ceramic element, is open on the first end face.The heat can then be transferred directly to the cooling medium via the ceramic element.

[0049] Furthermore, it is provided that at least one cross-flow section connecting the feed section and the discharge section is formed between the deflection section and the second end face

[0050] In contrast to what is known from the prior art, it is provided here that a cross-flow section is formed between the supply section and the discharge section. Such a cross-flow section offers an additional possibility of guiding the cooling medium from the supply section into the discharge section, in particular without a corresponding proportion of cooling medium having to be guided via the deflection section. It is preferably provided that the cross-flow section is designed such that less than a third, preferably less than an eighth and preferably less than a fifteenth of the flow volume guided through the deflection section is guided through the cross-flow section, in particular an individual or all of the cross-flow sections. It has surprisingly been found that such cross-flow sections advantageously allow the thermal resistance of the entire heat sink element to be adapted.In particular, this also makes it possible to reduce the number of layers used and thus also the size of a second thickness of the heat sink element, which has a beneficial effect on adapting the mass distribution on the front and back of the ceramic element for the purpose of compensating for deflection forces. Particularly in production, the formation of a cross-flow cross-section means that plastic deformations are promoted during cooling during the bonding process, which advantageously have the effect of minimizing deflection. Preferably, a plurality of cross-flow sections are provided, in particular arranged one above the other. Preferably, a plurality of cross-flow sections are provided which are arranged one above the other in a direction running perpendicular to the main extension plane and / or next to one another in a direction running parallel to the main extension plane.

[0051] In particular, it is provided that the heat sink element is constructed from an arrangement of web elements arranged to form a partition between the supply section and the discharge section, in which the at least one cross-flow section, preferably a plurality of cross-flow sections, is arranged. This provides a particularly lightweight heat sink element that also exhibits advantageous deflection behavior. The web elements also preferably form partitions between adjacent cooling channels. The web elements preferably delimit the respective flow cross-section and, in particular, define its shape.

[0052] Preferably, the web elements connect adjacent surface sections. The adjacent surface sections are preferably part of a post section, which particularly preferably extends between the first and the second end face. The surface sections advantageously ensure the necessary stability in the heat sink element. Preferably, the surface sections are distributed in a two- or three-dimensional arrangement in the heat sink element. It is conceivable that surface sections are provided in the heat sink element which, within a plane, are each connected via web elements to all adjacent surface sections and / or surface sections which, within a plane, are connected to less than 75%, preferably to less than 55%, and particularly preferably to less than 50% of all adjacent surface sections.A web element is understood, in particular, to mean those subsections in a layer that are connected in a planar manner along a plane running parallel to the main extension plane and that have a preferred extension direction along which the web elements have an extension that is many times, preferably at least five times, preferably at least eight times, and particularly preferably ten times, greater than a web width measured perpendicular to the preferred extension direction. The surface sections either have no preferred extension direction or, at most, have extensions along the preferred extension direction that do not exceed five times, preferably eight times, and particularly ten times the web width.

[0053] Furthermore, it is preferably provided that the at least one cross-flow section has a flow cross-section which has a value between 0.005 mm 2 and 0.07 mm 2, preferably between 0.01 mm 2 and 0.055 mm 2 and particularly preferably between 0.015 mm 2 and 0.04 mm 2 It has been found that with such flow cross-sections, sufficient cooling medium can still reach the deflection section, while at the same time the openings forming the cross-flow cross-section are large enough to reduce the likelihood of clogging by particles in the cooling medium. Here, too, the flow cross-section is defined as an area perpendicular to the cross-flow direction and is preferably delimited by web elements.

[0054] It is preferably provided that the heat sink element has at least a first layer and a second layer, which are arranged one above the other to form the at least one cooling channel. It is preferably provided that the heat sink element is composed of a system that has a plurality of first layers and a plurality of second layers, wherein first layers and second layers are distinguishable from one another in their geometric design. In particular, it is conceivable that the first layer and the second layer are produced as form-etched parts that are arranged one above the other and subsequently connected to one another. It is also conceivable that the heat sink element is constructed exclusively from a plurality of first layers.

[0055] The first layer and the second layer preferably have a thickness that assumes a value between 0.1 mm and 0.8 mm, preferably between 0.1 and 0.5 mm and particularly preferably between 0.1 and 0.3 mm. In particular, it is preferably provided that recesses are let into the first and the second layer, which are arranged specifically one above the other in order to form a corresponding cooling channel, preferably a cooling channel section that extends along the stacking direction. In this case, for example, by a corresponding offset of the first layer and the second layer or of the first recess and the second recess, an angle of inclination of the cooling channel and / or a spiral or stepped course of the cooling channel can be set, which can in particular contribute to the turbulence of the flow within the cooling channel, which in turn can increase the efficiency of the cooling channel.It is conceivable for the recesses to be star-shaped and / or to have projections extending into the recess in order to additionally influence the flow behavior during flow along the flow direction. Preferably, the first layer and the second layer are offset from one another in a direction parallel to the main extension plane, preferably by a distance between 0.01 mm and 0.5 mm, preferably between 0.01 mm and 0.25 mm, and particularly preferably between 0.01 and 0.15 mm. This makes it possible to achieve a desired offset, in particular for a spiral course, which has proven particularly advantageous for swirling the cooling medium.

[0056] Furthermore, it is preferably provided that an offset of the first layer and the second layer, or of the first recess and the second recess, increases along the flow direction from the second end face toward the first end face. This can correspondingly increase the degree of turbulence in the regions of the cooling channel that are arranged as close as possible to the first end face to be cooled.

[0057] It is preferably provided that the first layer and / or the second layer have surface sections, wherein the surface sections are connected to one another via web elements. The surface sections are arranged congruently with one another, in particular when the first and second layers are assembled and stacked. The surface sections of the first and second layers are preferably of identical design, in particular arranged at the same locations. This advantageously makes it possible to realize a post section in the heat sink element, preferably one that runs continuous from the first to the second end face, which is particularly advantageous for the stability of the heat sink element. A shape of the surface section measured parallel to the main extension plane can be rectangular, polygonal, square, circular and / or oval. The surface sections are preferably arranged in a checkerboard pattern with respect to one another.arranged in a defined two-dimensional pattern to one another. The web elements connect the respectively adjacent surface sections. In this case, it is preferably provided that surface sections are provided which are connected to the adjacent surface sections of the same layer via two linearly independent directions. It is preferably provided that the first layer and the second layer also comprise surface sections which have a reduced number of connections with web elements. For example, it is conceivable for a surface section to have fewer than three web elements which protrude from the surface section along the main extension plane. In this way, an enlarged recess can be deliberately produced in the first layer and the second layer by deliberately omitting web elements between individual surface sections.

[0058] In particular, it is provided that the surface sections and web elements are connected to one another in a grid-like manner, in particular to form a first layer and / or a second layer. Preferably, the surface sections and / or web elements are designed in such a way that star-shaped recesses are created. This advantageously also makes it possible to influence the deformation and / or rigidity of the heat sink element.

[0059] It is particularly preferred if the web elements that connect the surface sections to one another do not run in a straight line along a plane that extends parallel to the main extension plane. For example, the web element is angled and / or curved. A wave-shaped design is also conceivable. It has been found that non-straight web elements can create a certain degree of flexibility, which has proven particularly advantageous for the mutual compensation of forces acting on the ceramic element, especially during cooling after bonding the ceramic element and metal layer. The geometric design can be used to specifically adjust stiffness, for example. This advantageously makes it possible to counteract or specifically counteract bending, for example.

[0060] It is preferably provided that the first layer and the second layer are arranged one above the other in such a way that the non-straight course of the web elements arranged one above the other creates an opening for forming the cross-flow section. In other words: by means of the layers arranged one above the other, and in particular in the sections in which the web elements are provided, it is possible to create the corresponding opening that allows a desired cross-flow. In a plan view of the first and second layers arranged one above the other along a stacking direction, the web elements arranged one above the other form a boundary in the form of a diamond-shaped cross-section. Alternatively, depending on the shape of the web elements, this can also be a cross-section that is at least elliptical or similar to an ellipse.

[0061] Furthermore, it is conceivable for the first openings in the first layer and the second openings in the second layer to be laterally offset from one another along a direction running parallel to the main extension plane, for example without being twisted, in order to thus create a cross-flow section. It is also conceivable for the first openings in the first layer and the second openings in the second layer to be offset without forming a cross-flow section, since this also creates flexibility in the heat sink element that is advantageous for deformation. It is also preferably conceivable for the surface sections to be offset from one another. This can, for example, additionally create turbulence.

[0062] Preferably, a plurality of cross-sectional flow sections arranged one above the other is provided, in particular at least one cross-sectional flow section is provided for each pair of first and second layers.

[0063] By implementing a plurality of cross-sectional flow sections, it is advantageously irrelevant whether one cross-sectional flow section is blocked. In such cases, sufficient other cross-sectional flow sections are provided, ensuring crossflow to a certain and desired extent, enabling a reduction in thermal resistance.

[0064] Preferably, the stacked first layers and second layers form a continuous post section. This post section serves in particular to increase stability, especially along a direction running parallel to the stacking direction. The post sections preferably provide the rigidity that is particularly required during the sintering process. In addition, the post section proves to be advantageous for heat transfer. It is also conceivable for the stacked layers to have surface sections of different sizes, for example to obtain a post section that tapers towards the second end face. This likewise proves to be advantageous for the cooling efficiency of the cooling device. The post section preferably tapers gradually from layer to layer.

[0065] The present invention further provides a method for producing a power module according to the invention, wherein the heat sink element, a metal layer for component metallization, and a ceramic element are bonded together, preferably in a single bonding step. All advantages and properties described for the power module can be applied analogously to the subject matter of the method, and vice versa.

[0066] Further advantages and features will become apparent from the following description of preferred embodiments of the subject matter according to the invention with reference to the accompanying figures. Individual features of the individual embodiments can be combined with one another within the scope of the invention.

[0067] They show:

[0068] Fig.1 : schematic representation of a power module with heat sink element according to a first exemplary embodiment of the present invention,

[0069] Fig.2: schematic representation of a power module with a sectional view of a heat sink element according to a second exemplary embodiment of the present invention,

[0070] Fig. 3 schematic representation of a power module with a sectional view of a heat sink element according to a third exemplary embodiment of the present invention,

[0071] Fig. 4 shows a schematic representation of a cutout for a heat sink element for a power module according to a fourth exemplary embodiment of the present invention and Fig. 5a to 5c show a schematic representation of a cutout for a heat sink element for a power module according to a fifth exemplary embodiment of the present invention and

[0072] Fig. 6 schematic representation of a cutout for a heat sink element for a power module according to a sixth exemplary embodiment of the present invention

[0073] Figure 1 shows a power module 10 according to a preferred embodiment of the present invention. Such a power module 10 comprises a component metallization 20, a ceramic element 25, and a heat sink element 1. The component metallization 20 is preferably a structured metal layer in which conductor tracks and / or electronic connections are formed by the structuring. This makes it possible to use the component metallization 20 for circuits or circuit systems. For this purpose, for example, electrical components or wire bonds are connected to the connection surfaces and / or conductor tracks of the component metallization 20. The structuring (not shown) ensures electrical insulation between the individual metal sections in the component metallization 20.For this purpose, the structuring extends to a ceramic element 25, which acts as an insulating element for the insulation between the metal sections, which in turn are connected to the ceramic element 25.

[0074] The main task of the heat sink element 1 is to ensure that the heat generated during operation of the power module 10 is effectively dissipated at the component metallization 25 in order to prevent corresponding damage to the power module 1 and, in particular, to avoid endangering or reducing the performance of the power module 1. For the power modules 1 described here, particularly with the present choice of material for the insulation element, it has proven to be a common approach for a metal layer, which is bonded to the ceramic element 25 to form the component metallization 20, to be bonded to the ceramic element 25 together with a backside metallization on the ceramic element 25 opposite the component metallization 20.

[0075] This serves the purpose of counteracting thermomechanical stresses on the front side of the ceramic element 25, which are caused by the different expansion coefficients of ceramic and metal and would lead to deflection without back-side metallization. Without appropriate compensation, the different thermal expansion coefficients would lead to deflection of the metal-ceramic substrate, particularly in the event of a temperature change during the bonding process. Appropriate compensation is therefore ideally achieved if the metal layer bonded to the component side is essentially symmetrical to the back-side metallization, i.e., comparable or identical, particularly with regard to dimensions, i.e., thickness and extension. In this way, essentially compensating thermomechanical stresses act on the ceramic element 25 on opposite sides.

[0076] According to the prior art, it is common practice to subsequently connect a cooler to the corresponding backside metallization to ensure the appropriate cooling performance for the power module 10. This is usually done on the customer side and is separate from the manufacturing process of the metal-ceramic substrate. This not only results in an undesirable additional work step, but can also affect the maximum possible efficiency and cooling performance of a heat sink element 1 and thus the overall performance of the power module 10, especially if optimal coordination is not achieved.

[0077] In the present case, it is preferably provided that the heat sink element 1 is or is directly connected to the ceramic element 25. In particular, it has been found that it is possible to connect a heat sink element 1 to the ceramic element 25 without causing deflections that would render the power module 1 unusable or reduce its performance efficiency. In particular, it is provided that the component metallization 20, the ceramic element 25, and the heat sink element 25 each extend along a plane running parallel to the main extension plane HSE and are arranged one above the other in a stacking direction S running perpendicular to the main extension plane HSE. The ceramic element 25 is arranged between the component metallization 20 and the heat sink element 1.The component metallization 20 has a first thickness D1 measured in the stacking direction S, and the heat sink element 1 has a second thickness D2 measured in the stacking direction S. The ceramic element 25 has a third thickness D3 measured in the stacking direction S. In the exemplary embodiment shown in Figure 1, it is provided that the heat sink element 1 has a second thickness D2 which is greater than the first thickness D1 of the component metallization 20. Such dimensioning of the heat sink element 1 and component metallization 20 would normally result in considerable deflection due to the significantly greater accumulation of material on the back side of the ceramic element 25, in particular if the heat sink element 1 with the second thickness D2 is or is directly and immediately connected to the back side of the ceramic element 25.It has now surprisingly been found that it is possible to design the heat sink element 1 such that the deflection of the power module 10 is more than five times smaller, preferably more than eight times smaller, and particularly preferably more than ten times smaller than the deflection of a reference power module with dimensions corresponding to that of the power module 10, wherein the reference power module is designed with a solid heat sink element 1. To reduce the deflection of the power module 10 compared to a reference power module of the same size, it is provided, for example, that a plurality of cooling channels 30, 30, in particular microchannel cooling channels, which are embedded in the heat sink element 1, ensure that a corresponding deflection of the power module 10 is reduced.

[0078] In particular, it has been found, for example, that deflection can be reduced in this way and an immediate and direct connection of the heat sink element 1 to the back of the ceramic element 25 is also possible. For this purpose, it is particularly preferred, for example, if the component metallization 20 has a first mass and the heat sink element 1 has a second mass, wherein the second mass deviates from the first mass by only less than 160%, preferably not more than 120%, and particularly preferably not more than 80%. In other words, despite the significant differences between the first thickness D1 and the second thickness D2, it is proposed to design the heat sink element 1 such that the mass distribution on the front side of the ceramic element 25 and the back of the ceramic element 25 are thermomechanically comparable, for example by having a correspondingly large number of cooling channels embedded in the heat sink element 1.Through additional geometric distributions of the respective mass, it is then advantageously also possible to initiate corresponding leverage effects, which are also advantageous for compensating for corresponding deflection. The person skilled in the art will draw on corresponding empirical values ​​and / or simulations, which cause a corresponding mass distribution in the heat sink element 1, which correspondingly reduces the deflection of the power module 10. An exemplary design of the heat sink element 1 can be seen in detail in Figures 5b and 5c. It is clear that further material distributions are conceivable, which should also be included here.Thus, as a departure from the usual approach, it is proposed that the heat sink element 1 be bonded, for example, immediately and directly to the ceramic element 25, preferably in a joint bonding process with the metal layer provided for the component metallization 20, by designing and constructing the mass distribution on the rear side of the ceramic element 25 for the heat sink element 1 accordingly to reduce deflection. It is also preferably provided that a first extent A1 of the component metallization 20, which is dimensioned essentially parallel to the main extension plane HSE, is in a ratio to a second extent A2 of the heat sink element 1, which extends parallel to the main extension plane HSE. The ratio of the first extent A1 to the second extent A2 preferably assumes a value between 0.9 and 1, preferably between 0.95 and 1, and particularly preferably between 0.98 and 1.Accordingly, it has proven advantageous if the second dimension A2 of the heat sink element 1 is larger than the first dimension A1 of the component metallization 20 in order to minimize leverage on the rear side compared to the front side of the ceramic element 25. In particular, the manufactured metal-ceramic substrate or power module 10 is initially a large card, from which individual metal-ceramic substrates or power modules 10 are then created by separating, preferably along a predetermined breaking point, which was generated, for example, with an ultrashort pulse laser. The large card is characterized in particular by the fact that it already has a connected heat sink element.

[0079] Figure 2 shows a power module 10 according to a second exemplary embodiment. In particular, Figure 2 shows an example of a course of possible cooling channels 30, 30'. In particular, Figure 2 shows two different possible types of cooling channels 30, 30' with two different general flow paths. In principle, it is preferably provided if the cooling channels 30, 30' of the same type, in particular only of a single type, are embedded in a power module 10. To illustrate different types of cooling channels 30, these are illustrated in a simplified manner in the common heat sink element 1 in Figure 2. The heat sink element 1 preferably has a first end face S1 and a second end face S2.The first end face S1 and the second end face S2 lie opposite one another along the stacking direction S in the power module 10, and the first end face S1 faces the ceramic element 25 and thus the surface to be cooled. The cooling channel 30, 30' is embedded or integrated into the base body of the heat sink element 1 and arranged between the first end face S1 and the second end face S2. In the exemplary embodiment shown in Figure 2, the heat sink element 1 has a first opening 41 on the second end face S2, as well as a second opening 42, which is also preferably arranged in the second end face S2. A cooling medium, in particular a fluid cooling medium, is admitted into the cooling channel 30, 30' via the first opening 41, while the medium used for cooling leaves the heat sink element 1 via the second opening 42. The cooling channel 1 preferably has a supply section 31, a deflection section 32, and a discharge section 33.The feed section 31 guides the cooling medium along a flow direction SR to a deflection section 32. The feed section 31 guides the cooling medium in particular in the direction of the first end face S1 of the heat sink element 1. The deflection section 32 in turn guides the cooling medium along a flow direction SR to the discharge section 33 and the discharge section 33 preferably guides the cooling medium to the second opening 42, ie in particular in the direction of the second end face S2.

[0080] Furthermore, it is preferably provided that the deflection section 32 runs essentially in sections parallel to the first end face S1 of the heat sink element 1 in order to ensure cooling over the most surface area possible. In other words: the actual cooling effect or a large contribution to the cooling effect emanates from the deflection region 32, which is preferably arranged as close as possible to the ceramic element 25. Preferably, a distance A3 measured in the stacking direction S between the deflection region 32 and the ceramic element 25 is less than 250 pm, preferably less than 150 pm and particularly preferably less than 100 pm. The respectively successive flow directions SR in the supply section 31, deflection section 32 and discharge section 33 preferably define a general flow pattern in the cooling channel 30, 30'.

[0081] In the embodiment shown on the left, the general flow path is substantially U-shaped, while in the embodiment of a cooling channel 30, 30' shown on the right, a substantially V-shaped path is shown. Here, the flow direction SR in the supply section 31 is inclined or angled to a flow direction SR in the discharge section 33, wherein an angle between the flow directions SR in the supply section 31 and discharge section 33 preferably assumes a value between 0° and 90°, preferably between 0° and 60°, and particularly preferably between 0° and 45°.

[0082] In particular, it has been found to be advantageous if the flow velocity in the deflection region 32 is controlled, in particular increased. For this purpose, it is particularly preferably provided that the flow cross-sections are adapted accordingly during the flow along the flow path. It has been found particularly preferably that a first flow cross-section Q1 in the feed section 31, dimensioned perpendicular to the flow direction SR, is larger than a second flow cross-section Q2 in the deflection section 32, dimensioned perpendicular to the flow direction SR. In the exemplary embodiment of the cooling channel 30 shown on the left in Figure 2, the respectively dimensioned flow cross-sections are aligned perpendicular to one another due to the general flow path. The first flow cross-section Q1 is preferably determined in the region of the first opening 41.Furthermore, it is preferably provided that a third flow cross-section Q3 of the discharge section 33, dimensioned perpendicular to the flow direction SR, is formed, particularly in the region of the second opening 42. It has proven particularly advantageous, particularly for a pressure drop over the flow path, if a ratio of the second flow cross-section Q2 to the first flow cross-section Q1 is less than 0.5, preferably less than 0.4, and particularly preferably less than 0.3. The flow cross-section is dimensioned, in particular, as the area delimited by the respective channel walls assigned to the cooling channel 30, 30'. It is also conceivable for the first flow cross-section Q1 to decrease in the direction of the deflection section 32, in particular decreases stepwise and / or continuously, and / or for the third flow cross-section Q3 to increase in the direction of the second opening 42, in particular increases continuously and / or stepwise.

[0083] Furthermore, it is preferably provided that the third flow cross-section Q3 is larger than the second flow cross-section Q2 and / or substantially corresponds to the first flow cross-section Q1. By correspondence, the person skilled in the art understands in particular that a deviation between the first flow cross-section Q1 and the third flow cross-section Q3 is not greater than 10%, preferably not greater than 5%, and particularly preferably not greater than 2.5% of the mean value of the first flow cross-section Q1 and the third flow cross-section Q3. In particular, the person skilled in the art also understands a flow cross-section to be an area, so that the length of the cross-section shown here in Figure 2 represents only a part of the flow cross-section to be used.

[0084] Figure 3 shows a power module 10 according to a third exemplary embodiment of the present invention. In particular, the power module 10 shown here is characterized by a heat sink element 1 in which the cooling channel 30, 30' is designed such that a cross-flow section 50 is formed. The cross-flow section 50 is arranged between the second end face S2 and the deflection section 32 and connects the supply section 31 to the discharge section 33, in particular upstream of the deflection section 32, i.e. before a portion of the cooling medium reaches the deflection section 32. As a result, a portion of the cooling medium is already deflected before reaching the deflection section 32 and discharged into the discharge section 33. Surprisingly, it has been found that this can increase the overall cooling efficiency of a power module 10.In particular, it has been found that this can improve the thermal resistance of the heat sink element 1. Furthermore, the power module of Figure 3 is characterized in that the heat sink element 1 is flush with the ceramic element 25 at its outer periphery, preferably completely. This is also a preferred embodiment for the embodiments of the other figures.

[0085] Figure 4 shows an arrangement of a first layer 60 and a second layer 70, which are arranged one above the other along a stacking direction S in order to form part of a cooling channel structure in the heat sink element 1. In particular, it is provided that the first layer 60 and / or the second layer 70 have web elements 61, 71. These web elements 61, 71 preferably connect adjacent surface sections 62, 72, wherein the surface sections 62, 72 of the first layer 60 and second layer 70 arranged one above the other are particularly preferably arranged congruently one above the other, in particular to form a post section 67 in the heat sink element 1. Such post sections 67 prove to be advantageous in particular because they additionally serve to stabilize the heat sink element 1, in particular along a direction running parallel to the stacking direction S.In the exemplary embodiment shown in Figure 4, the surface sections 62, 72 are essentially square. It is also conceivable that a circular or elliptical geometry is selected and / or a rectangular and / or a polygonal cross-sectional shape. Furthermore, it is preferably provided that the web elements 61, 71 connecting the surface sections 62 do not run in a straight line. In the exemplary embodiment shown in Figure 4, the web element 61, 71 is angled, in particular forming an angle between 80° and 140°, preferably between 90° and 120° and particularly preferably between 90° and 100°. In other words: the web element 61, 71 comprises two sub-segments that run at an angle to one another. Alternatively, it is conceivable that a curved line is provided for the web element 61, 71 as a non-straight line.Figure 4 shows a plan view of a first layer 60 and a second layer 70, which are arranged one above the other along the stacking direction S. By appropriately dimensioning or designing the first layer 60 and second layer 70 or by appropriately aligning the first layer 60 and the second layer 70, it is possible for the web elements 61, 71 to be oriented in opposite directions to one another. In particular, they are designed such that the web elements 61, 71 form an opening in a plan view, which is delimited by the web elements 61 of the first layer 60 and the web elements 71 of the second layer 70 in a viewing direction that runs parallel to the stacking direction S. This opening forms the cross-flow section 50. In the exemplary embodiment shown in Figure 4, this opening is particularly diamond-shaped.It is also conceivable that other geometries, in particular polygonal or elliptical or circular geometries, are designed here.

[0086] The term web element 61, 71 is to be understood in particular as meaning those partial sections which are connected in a planar manner along a plane running parallel to the main extension plane and which have a preferred extension direction along which the web elements 61, 71 have an extension which is many times, preferably at least five times, greater than a web width B measured perpendicular to the preferred extension direction. The surface sections 62, 72 either have no preferred extension direction or at most have extensions along the preferred extension direction which do not exceed five times the web width B.

[0087] In particular, in the embodiment of Figure 4, it is provided that the surface sections 62, 72 are arranged in a checkerboard pattern relative to one another, and the respective surface sections 62, 72 are connected on all sides, ie, on all four possible sides, to the respective adjacent surface sections 62, 72 via the web elements 61, 71. Thus, the first layer 60 and / or the second layer 70 are preferably designed in a grid-like manner.

[0088] Figures 5a to 5c show a further design option for a heat sink element 1 according to an exemplary embodiment. In particular, Figure 5a shows a plan view of a first layer 60 and a second layer 70, which are arranged one above the other along the stacking direction S. In principle, it is conceivable for the first layer 60 and the second layer 70 - this applies to the exemplary embodiment in Figure 4 and the exemplary embodiment in Figures 5a to 5c - to be arranged alternately one above the other in multiple layers. Alternatively, it is conceivable for a first number of first layers 60 to be arranged one above the other and a second number of second layers 70 to be arranged one above the other, which in turn are arranged one above the other. In other words: a first number of first layers 60 is arranged over a second number of second layers 70. This makes it possible to determine the corresponding position of a cross-sectional flow section 50 orto specify the number of cross-flow sections 50. The first number of first layers 60 does not have to match the second number of second layers 70. It is particularly preferably provided that a heat sink element 1 is constructed from at least a plurality, preferably at least five, particularly preferably at least eight and particularly preferably at least ten individual layers, wherein the plurality of individual layers particularly preferably comprises only the first layer 60 and the second layer 70 for forming the feed section 31 and the discharge section 33. The deflection section is preferably formed by a third layer 80 and / or fourth layer (not shown) or a plurality of third layers 80 and / or fourth layers.The first layer 60, the second layer 70, the third layer 80 and / or fourth layer differ, for example, with regard to the orientation of the web elements 61, 71 and / or the number of web elements 61, 72 and / or the size of the web elements 61, 71 and / or with regard to the arrangement, size and / or number of the surface sections 62, 72. The alternating arrangement thereby creates an uneven inner side of the cooling channel, which promotes turbulence in the cooling medium.

[0089] Figure 5b shows a first perspective view of the stack of first layer 60 and second layer 70. Here, the post section 67 can also be seen, which preferably extends from the first end face S1 to the second end face S2, in particular extending continuously. Furthermore, it can be seen that a plurality of superimposed cross-flow sections 50 are formed by the web elements 61, 71 arranged one above the other. Figure 5c also shows a further perspective view of the heat sink element 1. In particular, the exemplary embodiment of Figures 5a to 5c differs from that of Figure 4 in that surface sections 62, 72 are provided which are free of connection to an adjacent surface section 62, 72 in at least one direction.Preferably, surface sections 62, 72 are connected to adjacent surface sections 62, 72 via web elements 61, 71 along a first direction, and are not connected to adjacent surface sections 62, 72 along a second direction, wherein the first direction and second direction lie in a plane running parallel to the main extension plane HSE and are arranged at an angle to one another, in particular running at right angles to one another. This advantageously defines the flow cross-section Q1 and / or the third flow cross-section Q3, in particular increasing it, in order to correspondingly also generate a larger first flow cross-section Q1 or third flow cross-section Q3 compared to the second flow cross-section Q2 in the deflection section 32.It is particularly preferred if supply sections 31 and discharge sections 33 are realized by the corresponding stacking of the individual layers, wherein the deflection sections 32 are designed such that, for example, in the case of two adjacent cooling channels 30, 30', the discharge sections 33 are arranged next to one another. In other words: two discharge sections 33 of two adjacent cooling channels 30, 30' lie between two supply sections 31 of the adjacent cooling channels. This particularly simplifies the discharge of the cooling medium via a corresponding 30, 30' distribution structure, since both discharge sections 33 can share a common discharge line in the distribution structure. For example, it is also conceivable for the first layer 60 and the second layer 70 to be identical in construction and to be rotated relative to one another, preferably rotated by 180°, stacked and joined.It is also conceivable that the first layer 60 and the second layer 70 are offset from one another in a direction parallel to the main extension plane HSE, preferably by a distance which assumes a value between 0.01 mm and 0.5 mm, preferably between 0.01 mm and 0.25 mm and particularly preferably between 0.01 and 0.15 mm.

[0090] Figure 6 shows a further design option for a heat sink element 1 according to an exemplary embodiment. In particular, only first layers 60 are stacked one above the other to form the supply section 31 and the discharge section 33. The web elements 61 are linear and connect the checkerboard-arranged surface sections 62. This results in rectangular recesses that define a first and third flow cross-section in the supply section 31 and the discharge section 33, respectively. This design proves to be particularly advantageous because it is comparatively simple to implement.

[0091] In the embodiment shown in Figure 6, it is provided that a plurality of third layers 80 are arranged one above the other in order to define a deflection section 32 with their recesses arranged one above the other. The third layers 80, which are arranged one above the other in a substantially identical manner, are arranged relative to one another in such a way that the recesses are congruent with one another. This results in essentially smooth inner sides in the deflection region 32. It is advantageous if the third layers 80 are offset from one another and / or a fourth layer (not shown) is provided in order to realize a profiling on the inner side in the deflection section 32, or in the transition from the feed section 31 to the deflection section 32 and / or in the transition from the deflection section 32 to the discharge section 33. This causes turbulence to be specifically induced in the area that is of particular importance for heat transfer.Preferably, the third layer 80 differs from the first layer 60 and / or second layer 70 in that at least one web element 61, which connects adjacent surface sections 62 to one another, is omitted compared to the first layer 60 and / or second layer 70, in particular in order to realize a larger recess which forms the deflection section 32.

[0092] List of reference symbols:

[0093] 1 heat sink element

[0094] 10 Power module

[0095] 20 Component metallization

[0096] 25 ceramic elements

[0097] 30, 30' cooling channel

[0098] 31 Feed section

[0099] 32 deflection section

[0100] 33 discharge section

[0101] 41 first opening

[0102] 42 second opening

[0103] 50 cross-flow section

[0104] 60 first layer

[0105] 61.71 Web element

[0106] 62.72 Area section

[0107] 67 post section

[0108] 70 second layer

[0109] 80 third layer

[0110] D1 first thickness D2 second thickness

[0111] D3 third thickness

[0112] A1 first extension

[0113] A2 second extension

[0114] A3 spacing

[0115] B Bridge width

[0116] S Stacking direction

[0117] S1 first page

[0118] S2 second page

[0119] Q1 first flow cross-section

[0120] Q2 second flow cross-section

[0121] Q3 third flow cross-section

[0122] SR flow direction

[0123] HSE main extension level

Claims

Claims 1. Power module (10) with a heat sink element (1), comprising a ceramic element (25), a component metallization (20) and the heat sink element (1), wherein the ceramic element (25), the component metallization (20) and the heat sink element (1) each extend substantially along a plane running parallel to a main extension plane (HSE) and are arranged one above the other in a stacking direction (S) running perpendicular to the main extension plane (HSE), wherein the ceramic element (25) is arranged between the component metallization (20) and the heat sink element (1), wherein the component metallization (20) has a first thickness (D1) measured in the stacking direction (S) and the heat sink element (1) has a second thickness (D2) measured in the stacking direction (S), wherein a ratio between the first thickness (D1) and the second thickness (D2) is less than 0.4, preferably less than 0.3 and particularly preferably less than 0.2, wherein the heat sink element (1),in particular by hollow areas in the heat sink element (1) and / or a targeted mass distribution within the heat sink element (1), is designed such that a deflection of the power module (10) is five times smaller, preferably eight times and particularly preferably ten times smaller than for a reference power module with a dimensioning corresponding to the power module (10), wherein the reference power module has a solidly formed heat sink element (1).

2. Power module (10) according to claim 1, wherein the heat sink element (1) is directly connected to the ceramic element (25).

3. Power module (10) according to one of the preceding claims, wherein the component metallization (20) has a first mass and the heat sink element (1) has a second mass, wherein the second mass deviates from the first mass by no more than 160%, preferably no more than 120% and particularly preferably no more than 80%.

4. Power module (10) according to one of the preceding claims, wherein the heat sink element (1) has web elements (61, 71), wherein the web elements to reduce the deflection (61, 71) preferably have a web width (B) which is less than 250 pm, preferably less than 200 pm and particularly preferably less than 150 pm.

5. Power module (10) according to one of the preceding claims, wherein the ceramic element (25) has a third thickness (D3) measured in the stacking direction (S), and the third thickness (D3) assumes a value of up to 500 pm, preferably a value of up to 300 pm, and particularly preferably a value of up to 250 pm or even a value of up to 200 pm.

6. Power module (10) according to one of the preceding claims, wherein the heat sink element (1) as a body defines a first volume through its outer circumference and hollow regions, for example in the form of cooling channels (30, 30'), in the heat sink element (1) occupy a second volume, wherein a ratio of the second volume to the first volume assumes a value which is greater than 0.5, preferably greater than 0.6 and particularly preferably greater than 0.

7.

7. Power module (10) according to one of the preceding claims, wherein the heat sink element (1) has hollow regions which are not intended for guiding the cooling medium, wherein the hollow regions not intended for guiding the cooling medium are preferably a continuation of an arrangement of cooling channels (30, 30') and / or are preferably arranged in the edge region of the heat sink element (1).

8. Power module (10) according to one of the preceding claims, wherein the heat sink element (1) further - a base body with a first end face (S1) which, in the installed state, faces a surface to be cooled, and a second end face (S2) opposite the first end face (S1), and - a cooling channel (30, 30') which is let into the base body between the first end face (S1) and the second end face (S2), wherein the cooling channel (30, 30') has a feed section (31), a deflection section (32) and a discharge section (33), wherein the cooling channel (30, 30') is for Formation of a general flow path is designed to convey a cooling medium in the feed section (31) in the direction of the first end face (S1), to transfer it in the deflection section (32) into the discharge section (33) and to convey it in the direction of the second end face (S2), wherein the feed section (31) has a first flow cross-section (Q1) dimensioned perpendicular to a flow direction (S) and the deflection section (32) has a second flow cross-section (Q2) dimensioned perpendicular to the flow direction (S), wherein a ratio of the second flow cross-section (Q2) to the first flow cross-section (Q1) is less than 0.5, preferably less than 0.4 and particularly preferably less than 0.

3.

9. Heat sink element (1) according to claim 8, wherein the cooling channels (30, 30') of the plurality of identically shaped cooling channels (30, 30') are formed separately from one another.

10. Heat sink element (1) according to one of the preceding claims, wherein a first opening (41) is formed in the feed section (31) in the second end face (S2), wherein a flow cross-section in the first opening (41) dimensioned perpendicular to the flow direction (SR) deviates from a first flow cross-section (Q1) of the downstream section of the feed section (31) by less than 15%, preferably less than 10% and particularly preferably less than 5% of the first flow cross-section (Q1) in the downstream section of the feed section (31).

11. Heat sink element (1) according to one of the preceding claims, wherein there is exactly one cross-flow section (50) per cooling channel (30, 30').

12. Heat sink element (1) according to one of the preceding claims, wherein the heat sink element (1) is directly connected to a ceramic element (25) or a distance between the deflection section (32) and the ceramic element (25) is less than 300 pm, preferably less than 200 pm and particularly preferably less than 100 pm.

13. Heat sink element (1) according to one of the preceding claims, wherein the heat sink element (1) is closed at the first end face (S1).

14. Power module (10) according to one of the preceding claims, wherein the heat sink element (1) - a base body with a first end face (S1) which, in the installed state, faces a surface to be cooled, and a second end face (S2) opposite the first end face (S1), - a cooling channel (30, 30') which is let into the base body between the first end face (S1) and the second end face (S2), wherein the cooling channel (30, 30') has a feed section (31), a deflection section (32) and a discharge section (33), wherein the cooling channel (30, 30') is designed to form a general flow path by conveying a cooling medium in the feed section (31) in the direction of the first end face (S1), transferring it in the deflection section (32) into the discharge section (33) and conveying it in the discharge section (33) in the direction of the second end face (S2), wherein at least one cross-flow section (50) connecting the feed section (31) and the discharge section (33) is formed between the deflection section (32) and the second end face (S2).

15. A method for producing a power module (10) according to one of the preceding claims, wherein the heat sink element (1), a metal layer for component metallization (20) and a ceramic element (25) are bonded to one another, preferably in a common bonding step.

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