Power modules and methods for manufacturing such power modules

Abstract

The present invention relates to a power module (10) comprising a heat sink element (1), the power module (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 extending parallel to the main extending surface (HSE), and one is positioned on top of the other in a stacking direction (S) extending perpendicular to the main extending surface (HSE), the ceramic element (25) is positioned between the component metallization (20) and the heat sink element (1), and the component metallization (20) is The heat sink element (1) has a first thickness (D1) measured in the direction of travel (S), and the heat sink element (1) has a second thickness (D2) measured in the stacking direction (S), the ratio of the first thickness (D1) to the second thickness (D2) being less than 0.4, preferably less than 0.3, and particularly preferably less than 0.2, and the heat sink element (1) is designed such that the deflection deformation of the power module (10) is 5 times smaller, preferably 8 times smaller, and particularly preferably 10 times smaller than that of a reference power module having dimensions corresponding to the power module (10), and the reference power module is a power module (10) having a solidly formed heat sink element (1).

Description

[Technical Field]

[0001] The present invention relates to a power module and a method for manufacturing such a power module. [Background technology]

[0002] Power modules are well-known in the prior art and offer the potential to provide circuitry or electrical connections between electronic or electrical components via corresponding connection areas and conductor tracks. It has been shown to be particularly advantageous to use ceramics as insulating elements to which the individual metal parts of component metallization are attached. Such ceramics possess relatively high insulating strength and, in particular, high temperature resistance. As the demands on such power modules and associated heat generation increase, so do the corresponding cooling systems designed to ensure that heat is efficiently dissipated.

[0003] A classic approach to providing a heat sink element is to bond a cooling structure with cooling fins to the back surface metallization of a metal-ceramic substrate. A cooling medium, particularly a coolant, passes through this arrangement of cooling fins to ensure sufficient heat dissipation. This back surface metallization is essential for the process of bonding the metal layer to the ceramic element, and therefore it is necessary to achieve bonding via back surface metallization. Otherwise, especially in the case of one-sided bonding of a metal layer to a ceramic element, the different coefficients of thermal expansion and associated thermomechanical stresses will bend the metal-ceramic substrate when the temperature changes, for example, during cooling after bonding.

[0004] As a further development of this relatively simple fin structure, the teachings in Patent Document 1 propose that a number of microchannels be embedded in a heat sink structure to cool a power module over a wide area. The substantially loop-shaped cooling channels guide the cooling medium as close as possible to the surface being cooled in the power module, while simultaneously guiding the cooling medium away from the corresponding cooling surface. Preferably, many of these cooling channels are supplied with the cooling medium through a common distribution structure.

[0005] In particular, loop-shaped cooling channels are provided as microchannels that are similarly designed and arranged parallel to each other. This makes it possible to direct the cooling medium to the area to be cooled specifically, and in particular ensures that the cooling on the cooling side of the heatsink element is distributed as uniformly as possible.

[0006] Furthermore, conventional technology typically involves providing customers with metal-ceramic substrates intended as power modules, and the customers bonding heat sinks to these substrates, particularly through backside metallization. Due to the separation of these two processes, the corresponding manufacturing processes are often isolated from each other, making it difficult to efficiently adapt the heat sinks to the metal-ceramic substrates. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] German Patent No. 102013109246 Specification [Overview of the project] [Problems that the invention aims to solve]

[0008] Therefore, the present invention aims to simplify the manufacturing process of a coolable power module based on the prior art, and in particular to improve the cooling efficiency and miniaturization of the power module. [Means for solving the problem]

[0009] The present invention solves this problem by the power module described in claim 1 and the method for manufacturing such a power module described in claim 10. Further description, drawings, and dependent claims include further non-limiting embodiments of the present invention.

[0010] According to the first embodiment, a power module having a heat sink element, Ceramic elements and Component metallization and, The heat sink element comprises, The ceramic element, the component metallization, and the heat sink element extend substantially along a plane parallel to the main extending surface, with one positioned on top of the other in a stacking direction perpendicular to the main extending surface, and the ceramic element is positioned between the component metallization and the heat sink element. The component metallization has a first thickness measured in the stacking direction, the heat sink element has a second thickness measured in the stacking direction, and the ratio between the first thickness and the second thickness is less than 0.4, more preferably less than 0.3, and most preferably less than 0.2. The heat sink element is designed such that the deflection of the power module is 5 times smaller, more preferably 8 times smaller, and most preferably 10 times smaller than that of a reference power module having dimensions corresponding to the power module, by means of, in particular, a targeted arrangement of the hollow area in the heat sink element, in particular, a targeted mass distribution within the heat sink element, or both, wherein the reference power module has a solidly formed heat sink element. In particular, the reference power module has a second thickness corresponding to a second thickness of the power module. The reference power module differs in nature from the power module only in that it is formed as a solid, non-hollow metal layer having a second thickness of the power module.

[0011] In contrast to methods known from the prior art, the shape of the heat sink element, particularly its internal shape, is provided to be used to compensate for the thermomechanical stress acting on the back and front sides of the ceramic element throughout the power module. This differs from the approach commonly used in the prior art, in particular, where the heat sink element is designed independently of the power module and simply bonded to the back surface metallization after the metal-ceramic substrate has been manufactured. This makes it possible to bond the heat sink element to the ceramic element, in particular, simultaneously, and more preferably during the bonding process. This avoids an additional step, namely subsequent bonding of the heat sink element. However, this can only be meaningfully implemented if the heat sink element is designed to exhibit reduced deflection compared to a reference power module (i.e., a power module with the same geometric design but a solid heat sink element). Experts understand "solid" to mean, in particular, a heat sink element without a hollow area (i.e., a metal layer or metal block that is essentially unstructured).

[0012] Therefore, it has been shown that it is entirely possible to ensure that the deflection does not impair, in particular not limit, or enable the use of a power module, despite the significantly different thicknesses (i.e., the ratio of the second thickness of the heatsink element to the first thickness of the component metallization is specified), even if the deflection does not impair, in particular limit, the function of the power module. Deflection is understood, in particular, to mean a deviation from a perfectly flat plane. Typically, deflection is a kind of curvature, and therefore, preferably, deflection can be defined as the angle formed between a plane extending tangentially through the apex of a bulge and a point that deviates from, or at best separates from, the path of the flat plane extending through the apex. This angle can be used, for example, as a benchmark for determining each deflection. The angle is determined for the reference performance module and the power module, with respect to the same distance from the apex.

[0013] For example, the 0.1 thickness has a value of 0.1 mm to 4 mm, more preferably 0.1 to 2 mm, most preferably 0.2 to 0.8 mm, and / or the 2nd thickness has a value of 0.5 mm to 6 mm, more preferably 1.0 to 5 mm, most preferably 1.5 to 4 mm, and even more preferably 2 to 3.5 mm.

[0014] The heat sink element can more preferably be formed from a metal layer or multiple metal layers. However, a composite structure in which metal and / or ceramic alternately determine the shape of the heat sink is also conceivable. A heat sink element consisting of ceramic layers is also conceivable. The individual layers can be produced from metal and / or ceramic materials. Materials that can be used for the metal layers include copper, aluminum, molybdenum, tungsten, nickel, and / or alloys thereof such as CuZr, AlSi, or AlMgSi, as well as laminates such as CuW, CuMo, CuAl, and / or AlCu, or MMCs (metal matrix composite materials) such as CuW, CuM, or AlSiC. Preferably, the ceramic layer or ceramic element includes, as the material for the ceramic, Al2O3, Si3N4, AlN, HPSC ceramics (i.e., ceramics having an Al2O3 matrix containing x percent ZrO2, e.g., Al2O3=HPS9 with 9% ZrO2 or Al2O3=HPS25 with 25% ZrO2), SiC, BeO, MgO, high-density MgO (>90% of theoretical density), and TSZ (tetragonal stabilized zirconia). It is also conceivable that the ceramic layer be designed as a composite ceramic or hybrid ceramic, in which case several ceramic layers with different material compositions are placed on top of each other and joined together to form an insulating element to combine various desired properties.

[0015] In particular, it is necessary to ensure a specific porosity in the heat sink element by providing appropriate cavities, thereby providing an equivalent mass distribution on the top and back surfaces of the ceramic element, and thereby adequately compensating for deflection. Such compensation is only possible if the heat sink element is designed to be correspondingly delicate and slender. Preferably, the ceramic element, especially when supplied as a component of the heat sink element, has a thermal conductivity greater than 80 W / mK, more preferably greater than 100 W / mK, and most preferably greater than 120 W / mK. This enables the achievement of favorable thermal resistance necessary for effective heat dissipation.

[0016] To reduce deflection, the heat sink element preferably has a plurality of three-dimensionally arranged web elements that together form cooling channels. These are assembled to form corresponding cavities that have a corresponding effect on deflection. The web elements preferably have a web width of less than 250 μm, more preferably less than 200 μm, and most preferably less than 150 μm. Such thin web widths have been shown to be advantageous in allowing plastic deformation during cooling in the bonding process. This contributes to the reduction of mechanical stress and has a positive effect on the degree of deflection. In particular, the web elements are designed to form, for example, a wall structure or partition wall that separates a supply part and a discharge part from each other, especially a relatively thin wall structure or partition wall. These can be plastically deformed relatively easily during cooling and can thus contribute to compensation to the desired extent.

[0017] The web elements are rectangular and / or square and / or circular along a plane measured perpendicular to the preferred direction, and / or have a cross-section that occupies an area of less than 0.08 mm 2 and more preferably less than 0.05 mm 2 and most preferably less than 0.038 mm 2 is provided.

[0018] Also, more preferably, the heat sink element, as a body, defines a first volume by its outer periphery, and the hollow area in the heat sink element occupies a second volume (e.g., determined as the complete filling of all cooling channels with liquid), and the ratio of the second volume to the first volume is provided with a value greater than 0.5, more preferably greater than 0.6, and most preferably greater than 0.7. It has been shown that as the proportion of the hollow area in the heat sink element increases, the compensation of thermo-mechanical stress in the heat sink element can be improved.

[0019] Preferably, the power module is designed as a metal-ceramic substrate and, in the manufactured state, has one or more metal layers bonded to the ceramic element structured. For example, after the bonding process, structuring is also performed, for example, by laser processing, etching, and / or machining, and this structuring provides for realizing conductor tracks and / or connections for electrical or electronic components.

[0020] In particular, a heat sink element is provided to be bonded directly to the ceramic element. Such a direct connection can be recognized in the manufactured metal-ceramic substrate, for example, along the path of the heat sink element, especially from the first front side to the second front side, by the fact that a uniform grain size distribution is obtained. In other words, it has not been shown that a different grain size is achieved in the partial section of the heat sink element directly adjacent to the ceramic element than in the rest of the heat sink element. This indicates that, in particular in the manufactured metal-ceramic substrate, the heat sink element itself is directly and directly connected to the ceramic element, especially to the back side of the ceramic element. Such a direct connection has been shown to be particularly advantageous as it eliminates the need for a time-consuming intermediate process where it is necessary to first metallize the back side and then bond the heat sink to the back side metallization.

[0021] More preferably, the component metallization has a first mass, the heat sink element has a second mass, and the second mass is provided to deviate from the first mass by less than 160%, more preferably less than 120%, and most preferably less than 80%. The corresponding mass distribution has been shown to be particularly advantageous for canceling out deflections. It is shown that the difference between the first mass and the second mass is relatively small despite a large difference in thickness. In addition to this, the overall power module becomes particularly light. This is more preferably combined, for example, with the corresponding arrangement of the individual wall structures in the heat sink element to generate a corresponding lever effect. This is not guaranteed, for example, with conventional approaches.

[0022] Furthermore, it is conceivable that the grain size affects the thermomechanical stress on the front and back surfaces of the ceramic element, and / or that these be taken into consideration. Most preferably, the component metallization has an average first grain size, and the heat sink element has an average second grain size, with the ratio of the average first grain size to the average second grain size being less than 0.7, preferably less than 0.5, and most preferably less than 0.25. In other words, the component metallization has a fine grain size, and the heat sink element has a coarse grain size. At a minimum, the corresponding grain size distribution is considered in the design of the heat sink element.

[0023] Furthermore, the mass distribution in the heat sink element may be influenced by the interconnected layers on top of each other. These layers have web width modulation along planes extending parallel to the main extending plane before being joined, which can particularly increase density in certain areas and cause a corresponding leverage effect. In addition, the solidification of the layers joined together to form the heat sink element may also affect deflection.

[0024] Most preferably, the ceramic element has a third thickness measured in the stacking direction, the third thickness having a value up to 500 μm, more preferably up to 300 μm, most preferably up to 250 μm, and even further down to 200 μm. This includes the respective limits, namely 500 μm, 300 μm, 250 μm, and 200 μm. It has been shown that it is possible to make the ceramic element this thin by appropriately designing the heat sink element. This is not possible, for example, if deflection occurs as expected relative to the reference module, because in such a case these relatively thin ceramic elements may break, and the function of the power module cannot be guaranteed.

[0025] In order to influence the thermomechanically compensating stress, it is particularly important to consider that a corresponding lever effect can also result in compensation of thermomechanically compensating stress through a proper mass distribution on the side surface of the heat sink element. In this context, those skilled in the art will particularly utilize experience with bonding processes and / or corresponding simulations that take into account, for example, the relevant material and geometric properties of the heat sink element. In particular, the heat sink element is designed to be porous and provided in particular to provide multiple cooling channels. The formation of a large number of cooling channels ensures a proper mass distribution, since the heat sink element has a corresponding number of cavities that reduce the mass without affecting the thickness of the heat sink element. This also makes it possible to provide a correspondingly lower second mass without reducing the thickness of the second heat sink element. Preferably, the heat sink element has more than 30, more preferably more than 90, and most preferably more than 150 cooling channels, in particular active cooling channels.

[0026] In particular, for this purpose, cooling channels are provided embedded in the heat sink element to influence the thermomechanical stress on the back surface of the ceramic element. Therefore, for example, the corresponding deflection can be counteracted by the target placement of the cooling channels. In particular, the deflection of the power module is reduced by the positioning of the cooling channels.

[0027] Furthermore, more preferably, the component metallization has a first extension extending parallel to the main extension plane, and the heat sink element has a second extension extending parallel to the main extension plane, and the ratio of the first extension to the second extension is provided to be 0.9 to 1, more preferably 0.95 to 1, and most preferably 0.98 to 1. In other words, more preferably, the component metallization and the heat sink element are provided to be slightly offset in the direction perpendicular to the stacking direction, in particular to avoid leverage effects as much as possible. The first and second extensions do not terminate flush with each other, in view of the stacking direction, in particular to provide a recess on the side of the ceramic element facing the component metallization. Most preferably, the heat sink element is provided to terminate flush with the ceramic element in a plane parallel to the main extension plane. In other words, the ceramic element does not protrude perpendicular to the stacking direction relative to the heat sink element.

[0028] Preferably, the heat sink element has a hollow area not intended for the flow of a cooling medium, which is preferably an extension of the arrangement of cooling channels and / or, preferably, provided to be located in the peripheral region of the heat sink element. In particular, the heat sink element is assumed to have hollow areas not intended for the flow of a cooling medium. In other words, in addition to cooling channels that carry the cooling medium during operation, further hollow areas are provided that more preferably serve only the purpose of reducing a second mass and achieving a favorable mass distribution. For example, the hollow areas have the form of cooling channels. In other words, the structure or arrangement of cooling channels is continuous in the heat sink element without specific cooling channels being provided for the actual flow of the cooling medium. They form so-called dummy structures that favorably contribute to the mass distribution. Preferably, such unused cavities or dummy structures are embedded in the peripheral region of the heat sink element.

[0029] More preferably, the heat sink element is provided to have cooling channels over a second dimension parallel to its principal extending surface. In particular, cooling channels are provided even in areas where cooling is not intended. For this purpose, the cooling channels are uniformly distributed over the entire second dimension of the heat sink element. This is particularly applicable to the formation of a master card. Therefore, it is preferable not to use a connecting structure that joins the individual heat sink portions provided for each individual substrate to each other in the master card.

[0030] In a further embodiment, a heat sink element, A base body having a first front facing the area to be cooled during installation, and a second front facing the opposite side of the first front, The device further comprises a cooling channel embedded in the base body between the first front surface and the second front surface, A heat sink element is provided, wherein the cooling channel has a supply portion, a deflection portion, and a discharge portion, and the cooling channel is designed to form an overall flow path in the supply portion for transporting a cooling medium toward the first front, to transfer the cooling medium in the deflection portion to the discharge portion, and to transport the cooling medium toward the second front in the discharge portion, wherein the supply portion has a first flow cross section measured perpendicular to the flow direction, and the deflection portion has a second flow cross section measured perpendicular to the flow direction, and the ratio of the second flow cross section to the first flow cross section is less than 0.5, more preferably less than 0.4, and most preferably less than 0.3.

[0031] In contrast to approaches known from prior art, the flow cross-section in the deflection area is specifically varied compared to the flow cross-section in the supply and discharge sections, and is provided to be significantly reduced. This deviates, in particular, from approaches aimed at achieving a constant flow velocity as much as possible in the channel. By specifically influencing the flow velocity, it is possible to reduce the pressure drop experienced by the coolant as it passes through the heat sink element. This is important for pumps that pump the coolant through the heat sink element. When the pressure drop of the coolant between the inlet and outlet is small, it is advantageous to use a pump with lower performance requirements.

[0032] Preferably, the first flow section and / or the second flow section and / or the third flow section are 0.1 mm in diameter to form microchannels. 2 Between 25 mm² and 0.1 mm², more preferably 0.1 mm 2 From 12.5mm 2 Between these two points, most preferably 0.1 mm 2 5mm 2 It has values ​​between . Therefore, these are cooling channels designed as microstructures. In other words, more preferably, the channel structure formed from multiple channel elements is provided to be a microchannel structure that is small enough that as many individual cooling channels as possible can be arranged adjacent to one another in order to ensure corresponding homogeneity and uniform supply to the area being cooled. In other words, preferably, the heat sink element is provided to have a microchannel cooling structure. This is in particular distinguished from a relatively large fin-like structure that provides a very large flow cross-section between individual fins, especially in a plane extending perpendicular to the direction of flow.

[0033] In particular, a plurality of separate cooling channels, each having a deflection portion, a supply portion, and a discharge portion, especially a transverse flow portion, are provided to be formed in the heat sink element. The separate cooling channels are preferably arranged adjacent to each other along two linear independent directions to form a two-dimensional arrangement of deflection areas. The cooling channels are preferably arranged in a repeating pattern. In particular, the cooling channels are arranged parallel to each other along two column directions.

[0034] Preferably, the supply and / or discharge portions are provided to be formed from a plurality of individual layers (i.e., a first layer and / or a second layer). This has the advantage that the individual voids arranged on top of each other in the layers are slightly offset from each other, thereby creating protrusions that project into the cooling channels. This makes it possible to generate additional turbulence in the cooling channels.

[0035] Furthermore, the first flow cross-section measured perpendicular to the flow direction in the supply section and / or the second flow cross-section in the discharge section are provided to deviate from the second flow cross-section in the deflection section by less than 15%, more preferably less than 10%, and most preferably less than 5%. The flow cross-section is generally measured in a plane perpendicular to the flow direction in each section, and more preferably, if the flow cross-section changes along the flow direction, it is measured as an average value. Thus, a heat sink element with relatively large free space is realized, thereby reducing the weight of the heat sink element. Furthermore, the flow cross-section measured perpendicular to the flow direction in the transverse flow section is provided to deviate from the second flow cross-section in the deflection section by less than 15%, more preferably less than 10%, and most preferably less than 5%.

[0036] The deflected portion may extend almost in a straight line in a direction parallel to the main extending surface. In particular, the first opening is provided to be formed in the supply portion at the second front. Furthermore, the flow cross-section measured perpendicular to the flow direction at the first opening is provided to deviate from the first flow cross-section at the downstream portion of the supply portion by less than 15%, more preferably less than 10%, and most preferably less than 5%. The downstream portion of the supply portion is preferably located midway between the deflection portion and the first opening, particularly between the deflection portion and the first opening. This ensures a particularly large volumetric flow rate that can be introduced into the supply portion and directed through the cooling channel.

[0037] In particular, the second opening is provided to be formed in the discharge portion of the second front. Furthermore, the flow cross-section at the second opening, measured perpendicular to the direction of flow, is provided to deviate from the third flow cross-section of the upstream portion of the discharge portion by less than 15%, more preferably less than 10%, and most preferably less than 5%. The upstream portion of the discharge portion is preferably located in the middle between the deflection portion and the second opening, particularly between the deflection portion and the second opening. This ensures a particularly large volumetric flow rate that can be guided through the cooling channel. In addition, nozzle effects are avoided. The first opening and / or the second opening are preferably sized to form the flow cross-section of the preceding paragraph.

[0038] Furthermore, multiple cooling channels, in particular multiple separate cooling channels, are provided so that each is connected to a common supply channel via a supply portion. Each deflection portion has its own supply portion. Thus, the supply portion is defined as the area between the supply channel and the deflection portion used by several separate cooling channels. In particular, it is provided so that there is exactly one transverse flow portion for each cooling channel.

[0039] Furthermore, more preferably, the heat sink element is provided such that the first front surface of the heat sink element is enclosed or has no recesses or openings. This means that, particularly with respect to the material composition, a continuous layer of material corresponding to one or more layers (i.e., a first layer, a second layer, a third layer, and / or a fourth layer) on which the heat sink element is formed is provided on the first front surface. This ensures a particularly durable connection, especially in critical areas exposed to severe temperature changes. The deflected portion, and therefore the cooling fluid, does not directly adjoin the object being cooled. This has the advantage of preventing damage or failure in this interface area. This extends the service life.

[0040] Furthermore, the first flow cross-section and / or the second and / or third flow cross-section may have a polygonal shape. Preferably, the first and / or third flow cross-section has a star-shaped cross-section, and preferably the second flow cross-section also differs from the first and / or third flow cross-section in terms of geometric shape, for example, being rectangular in design. By changing the geometric shape, for example from a star shape to a rectangular shape, it may be shown that turbulence is favorably promoted during the transition from the supply portion to the deflection portion, which is advantageous for heat transfer. Preferably, the first and / or third flow cross-section has a geometric shape with more angles than the second flow cross-section. Different geometric shapes have been shown to allow for specific and improveable adjustment of thermal resistance and pressure.

[0041] Furthermore, the flow directions in the supply, deflection, and discharge sections are provided to jointly form a general flow path. In particular, the flow direction in the supply section is directly connected to the flow direction in the deflection section. The same applies to the flow directions in the deflection and discharge sections.

[0042] Furthermore, the deflection portion is preferably intended to extend as parallel as possible to the surface being cooled, particularly the first front surface, in order to provide corresponding point cooling or surface cooling. The deflection portion may, for example, be inclined with respect to the main extending surface and / or have stepped and / or curved paths. The flow cross section is understood in particular as the spread that occurs in each cooling channel in a plane perpendicular to the direction of flow. Thus, what is defined herein is the area through which the cooling medium passes.

[0043] Preferably, multiple cooling channels of the same shape are provided, and the cooling channels are part of multiple cooling channels of the same shape. Preferably, more than 50 cooling channels, more preferably more than 100 cooling channels, and most preferably more than 200 cooling channels are provided to the heat sink element. This makes it possible to cool the first front surface as uniformly as possible, which is advantageous. It is also conceivable that multiple cooling channels be arranged in sub-sections. The corresponding clustering of cooling channels allows for targeted cooling of areas where higher heat generation is expected, for example, particularly during operation. This ensures increased cooling in these areas. Another advantage is that less cooling medium needs to pass through the heat sink element. It is also conceivable that multiple cooling channels of the same shape are formed primarily, and each of the multiple differs in terms of their type, i.e., they have different designs for the supply portion, deflection portion, and / or discharge portion.

[0044] Multiple cooling channels extend parallel to each other, more preferably along the column direction, and most preferably arranged in a staggered pattern parallel to each other. This advantageously allows for the joint supply of cooling fluid to the supply portions of adjacent cooling channels, or the joint discharge of cooling fluid mainly from the discharge portion, using a suitable distribution structure, such as that known from German Patent Application Publication No. 102016125338 (the disclosure of which is explicitly referenced in this regard). In particular, several columns of cooling channels arranged adjacent to each other along the column direction are provided to be oriented in a direction predetermined by the main extending surface. This results in a regular pattern of cooling channels in the heat sink element.

[0045] Preferably, the discharge area has a third flow cross-section measured perpendicular to the flow direction, and the ratio of the third flow cross-section to the second flow cross-section is provided to be less than 0.5, more preferably less than 0.4, and most preferably less than 0.3. In particular, the discharge area has a third flow cross-section measured perpendicular to the flow direction, and the ratio between the third flow cross-section and the first flow cross-section is provided to be less than 0.5, more preferably less than 0.4, and most preferably less than 0.3. The third flow cross-section may be larger than the second flow cross-section, or the second flow cross-section may be larger than the third flow cross-section. The first flow cross-section is most preferably essentially identical to the third flow cross-section. In other words, the flow cross-section decreases from a first opening through which the cooling medium enters the heat sink element to a deflected portion, and then increases again in the direction of a second opening through which the fluid exits the heat sink element.

[0046] Preferably, the supply portion is provided to begin at a first opening recessed particularly in the second front surface, and / or the discharge portion is provided to end at a second opening recessed particularly in the second front surface, with a first flow cross section determined in the area of ​​the first opening, and / or a third flow cross section determined in the area of ​​the second opening. Alternatively, the first and / or second openings may be introduced from a surface (i.e., from a surface connecting the first and second end surfaces, for example, essentially extending along the stacking direction) rather than being located on the second end face. Forming the first and second openings on the second front surface has been shown to be particularly advantageous for a distribution structure bonded to a heat sink element to provide supply and removal of a cooling medium. Preferably, the supply and discharge portions are provided so as to extend essentially parallel to each other or inclined at a certain angle to each other in order to form a U-shaped path, where the angle has a value of 0° to 120°, more preferably 0° to 90°, and most preferably 0° to 45°. In particular, the U-shaped design makes it possible to create cooling channels with the smallest possible lateral spread. This makes it possible to arrange as many cooling channels as possible in rows that extend parallel to each other, both front to back and adjacent to each other. In particular, the cooling channels form a two-dimensional arrangement and more preferably have a repeating pattern. By starting at an appropriate angle as described above, it is possible to favorably influence, for example, the flow velocity and to more easily compensate for manufacturing tolerances.

[0047] Furthermore, more preferably, the deflection area is provided to have an additional contour. For example, the additional contour may be a corrugated design of the channel wall in the deflection area facing the first front side. This can be achieved, for example, by corresponding recesses or protrusions in the metallization layer or metal layer that forms the cover layer of the heat sink element on the first front surface. Additional protruding web-like structures are also conceivable, for example, which also contribute to increasing heat transfer from the heat sink element to the coolant by bead-like and / or spherical edges.

[0048] Furthermore, more preferably, the supply portion and / or discharge portion are provided to have additional structures protruding into the cooling channel, which particularly increases the cooling efficiency and, in particular, increases or improves the heat transfer from the heat sink element to the coolant or cooling medium.

[0049] Preferably, the first flow cross section is provided to decrease along the flow direction, and in particular to decrease continuously, and / or the third flow cross section is provided to increase along the flow direction, and in particular to increase continuously. More advantageously, the heat sink element is provided to be enclosed at the first front. Alternatively, the first front is open, and the back surface of the ceramic element may form part of the cooling channel when bonded.

[0050] Furthermore, more preferably, a partition wall is provided between the supply portion and the discharge portion, the partition wall having a width measured parallel to the main extending surface, decreasing from the first front to the second front. This allows the corresponding leverage effect to be specifically modified and, at the same time, takes into account the fact that heat transfer from the heat sink element to the liquid is most efficient in the area directly adjacent to one-third or the first front.

[0051] The distance between the deflection portion and the ceramic element is provided to be less than 300 μm, more preferably less than 200 μm, and most preferably less than 100 μm. This allows the deflection portion to be positioned as close as possible to the ceramic element. This is possible when connection via back surface metallization is not required, especially when the first thickness of the component metallization is greater than the distance between the deflection portion and the ceramic element. The advantages resulting from this direct connection of the heat sink element are avoidance of heat diffusion and shortening of the heat path to optimize cooling performance. It is also conceivable that the deflection portion is directly adjacent to the ceramic element. In this case, the heat sink element directly bonded to the ceramic element has an opening at the first front surface. Heat can then be directly transferred to the cooling medium through the ceramic element.

[0052] Furthermore, one or more transverse flow portions are provided between the deflection portion and the second front surface, connecting the supply portion and the discharge portion. Unlike those already known from the prior art, here a transverse flow section is provided to be formed between a supply section and a discharge section. Such a transverse flow section provides, in particular, an additional possibility for guiding the cooling medium from the supply section to the discharge section without the need to guide a corresponding proportion of the cooling medium through a deflection section. More preferably, the transverse flow section is provided to be designed so that less than one-third, more preferably less than one-eighth, and more preferably less than one-fifteenth of the flow rate guided through the deflection section is guided through the transverse flow section, in particular one or all of the transverse flow sections. Surprisingly, such a transverse flow section has been shown to have the advantage of allowing the thermal resistance of the entire heat sink element to be adjusted. In particular, this allows for a reduction in the number of layers used, and therefore the magnitude of the second thickness of the heat sink element, thereby having a beneficial effect on adjusting the mass distribution on the front and back surfaces of the ceramic element for the purpose of compensating for bending forces. In particular, in manufacturing, the formation of the transverse flow section means that plastic deformation is facilitated during cooling during the bonding process, which has a beneficial minimizing effect on deflection. Preferably, multiple transverse flow sections are provided, in particular arranged on top of each other. Preferably, a plurality of transverse flow portions are provided, arranged on top of each other along a direction perpendicular to the main extending surface, and / or adjacent to each other in a direction parallel to the main extending surface.

[0053] In particular, the heat sink element is constructed from an arrangement of web elements positioned to form a partition between a supply section and a discharge section, within which one or more transverse flow sections, more preferably multiple transverse flow sections are arranged. This provides a particularly lightweight heat sink element that also behaves favorably with respect to deflection. The web elements also more preferably form partition walls between adjacent cooling channels. The web elements more preferably restrict the respective flow cross-sections and, in particular, determine their shape.

[0054] Preferably, the web element provides a joining of adjacent surface portions. The adjacent surface portions are more preferably part of a post portion extending between a first front face and a second front face, most preferably. The surface portions advantageously provide the stability required in the heat sink element. More preferably, the surface portions are distributed in a two-dimensional or three-dimensional arrangement in the heat sink element. The surface portions are provided to be joined to all adjacent surface portions via the web element in the plane of the heat sink element, and / or it is conceivable that the surface portions are provided to be joined to less than 75%, more preferably less than 55%, most preferably less than 50% of all adjacent surface portions in the plane.

[0055] The web element is understood to be a flat, continuous partial section having a preferred direction of extension, particularly in a layer extending along a plane parallel to the main plane of extension, and along this preferred direction of extension, the web element has an extent many times larger, more preferably 5 times or more larger, more preferably 8 times or more larger, most preferably 10 times larger than the web width measured perpendicular to the preferred direction of extension. The surface portions do not have the preferred direction of extension, or at most have an extent along the preferred direction of extension not exceeding 5 times, more preferably 8 times, most preferably 10 times the web width.

[0056] Furthermore, more preferably, one or more cross-flow portions are 0.005 mm 2 ~0.07 mm 2 More preferably 0.0 mm 2 ~0.055 mm 2 Most preferably 0.015 mm 2 ~0.04 mm 2The flow cross-section is provided to have a value of . In such a flow cross-section, sufficient cooling medium is still able to enter the deflected portion, and at the same time, the openings forming the transverse flow cross-section are shown to be large enough to reduce the possibility of clogging by particles in the cooling medium. Here again, the flow cross-section is defined as an area extending perpendicular to the transverse flow direction, and more preferably, is constrained by a web element.

[0057] Preferably, the heat sink element has one or more first layers and one second layer arranged on top of each other to form one or more cooling channels. Preferably, the heat sink element is provided as a system comprising a plurality of first layers and a plurality of second layers, wherein the first and second layers are distinguishable from each other in their geometric design. In particular, the first and second layers may be manufactured as mold-etched parts arranged on top of each other and then joined together. It is also possible that the heat sink element is constructed from only a plurality of first layers.

[0058] The 0.1 layer and the 2nd layer have a thickness of more preferably 0.1 mm to 0.8 mm, more preferably 0.1 to 0.5 mm, and most preferably 0.1 to 0.3 mm. In particular, preferably, gaps are provided between the first and second layers, which are positioned on top of each other, in order to form corresponding cooling channels, preferably cooling channel portions extending along the stacking direction. For example, by appropriately offsetting the first and second layers or the first and second gaps, it is possible to set the inclination angle of the cooling channels and / or the helical or stepped path of the cooling channels, which in turn contributes to turbulence of the flow in the cooling channels and, in turn, to increase the efficiency of the cooling channels. To further influence the flow behavior when the flow is along the flow direction, the gaps may be star-shaped and / or have projections protruding through the gaps. More preferably, the 0.01 layer and the second layer are offset from each other by a distance of preferably 0.01 mm to 0.5 mm, preferably 0.01 mm to 0.25 mm, and most preferably 0.01 to 0.15 mm in a direction extending parallel to the main extending plane. This makes it possible to achieve the desired deviation, particularly for helical paths, which have been shown to be especially advantageous for turbulent flow of the cooling medium.

[0059] Furthermore, more preferably, the displacement between the first layer and the second layer or between the first void and the second void is provided to increase along the direction of flow from the second front to the first front. This makes it possible to increase the degree of turbulence in the area of ​​the cooling channel that is located as close as possible to the first front that is being cooled.

[0060] The first and / or second layers have surface portions, which are connected to each other via web elements. The surface portions are arranged to be congruent to each other, particularly when the first and second layers are assembled and stacked. Preferably, the surface portions of the first and second layers are identical in shape and, in particular, located in the same position. This is advantageous as it is possible to mount post portions on the heat sink element, preferably extending from the first front to the second front, which is particularly advantageous for the stability of the heat sink element. The shape of the surface portions, measured parallel to the main extending surface, can be rectangular, polygonal, square, circular, and / or elliptical. Preferably, the surface portions are arranged in a checkerboard pattern or a defined two-dimensional pattern. Web elements join each adjacent surface portion to each other. More preferably, the surface portions are provided to be connected to adjacent surface portions of the same layer via two linearly independent directions. Preferably, the first and second layers also have such surface portions with a reduced number of connections to web elements. For example, a surface portion may have fewer than three web elements protruding from the surface portion along the main extending plane. This makes it possible to create larger voids in the first and second layers by intentionally omitting web elements between individual surface portions.

[0061] In particular, the surface portion and web element are provided to be joined in a grid pattern, especially to form a first layer and / or a second layer. Preferably, the surface portion and / or web element are designed to form star-shaped voids. This also allows for an influence on the deformation and / or rigidity of the heat sink element.

[0062] Most preferably, the web elements joining the surface portions do not extend linearly along a plane parallel to the principal extending surface. For example, the web elements are angled and / or curved. Corrugated designs are also conceivable. It has been shown that non-linear web elements are advantageous because they can create a certain degree of flexibility, which has been shown to be particularly beneficial for the mutual compensation of forces acting on the ceramic elements, especially during cooling after bonding the ceramic elements to the metal layers. Geometric design allows for, for example, specific adjustment of stiffness. This makes it possible, for example, to cancel out or specifically cancel out deflection.

[0063] Preferably, the first and second layers are positioned on each other such that the nonlinear paths of the bar elements positioned on each other form openings for forming transverse flow portions. In other words, appropriately positioned layers on each other allow for the creation of desired openings that enable appropriate transverse flow, particularly in portions where web elements are provided. In a top view of the first and second layers positioned on each other along the lamination direction, the web elements positioned on each other form a boundary of diamond-shaped cross-sectional form. Alternatively, depending on the shape of the web elements, this may also be at least elliptical or elliptical-like cross-sections.

[0064] Furthermore, the first opening in the first layer and the second opening in the second layer may be offset laterally from each other along a direction parallel to the main extending surface, for example, without twisting, in order to realize a transverse flow portion. More preferably, the first opening in the first layer and the second opening in the second layer may be offset without forming a transverse flow portion, which provides flexibility that causes deformation in the heat sink element. It is also conceivable that the surface portions may be offset from each other. This can, for example, provide additional turbulence.

[0065] Advantageously, multiple cross-sectional flow portions are provided, arranged on top of each other, and in particular, one or more cross-sectional flow portions are provided for each pair of the first and second layers. Implementing multiple cross-sectional flow portions is advantageous when one cross-sectional flow portion is blocked. In such cases, there are sufficient other cross-sectional flow portions to ensure that there is sufficient transverse flow to reduce thermal resistance.

[0066] The first and second layers, placed on top of each other, are provided to form a continuous post portion. This post portion functions to enhance stability, particularly along a direction extending parallel to the stacking direction. The post portion more preferably provides the rigidity particularly required in the sintering process. In addition, the post portion is shown to be advantageous for heat transport. Furthermore, the layers stacked on top of each other may have portions of different sizes to obtain a post portion that tapers toward a second front, for example. This is also shown to be advantageous for the cooling efficiency of the cooling device. In this case, it is more preferable that the post portion tapers gradually from layer to layer.

[0067] Another subject of the present invention is a method for manufacturing a power module according to the present invention, wherein the heat sink element, the metal layer for component metallization, and the ceramic element are connected to each other, preferably in a common bonding step. All advantages and characteristics described in relation to the power module can be similarly applied to the subject of the method, and all advantages and characteristics described in relation to the method can be similarly applied to the subject of the power module.

[0068] Further advantages and features can be derived from the following description of preferred embodiments of the invention with reference to the accompanying drawings. Individual features of individual embodiments can be combined with each other within the scope of the invention. [Brief explanation of the drawing]

[0069] [Figure 1]A schematic diagram of a power module having a heat sink element according to a first exemplary embodiment of the present invention. [Figure 2] A schematic diagram of a power module, showing a cross-sectional view of a heat sink element according to a second exemplary embodiment of the present invention. [Figure 3] A schematic diagram of a power module, showing a cross-sectional view of a heat sink element according to a third exemplary embodiment of the present invention. [Figure 4] A schematic diagram of a portion of a heat sink element for a power module according to a fourth exemplary embodiment of the present invention. [Figure 5A] A schematic cutout of a heat sink element for a power module according to a fifth exemplary embodiment of the present invention. [Figure 5B] A schematic cutout of a heat sink element for a power module according to a fifth exemplary embodiment of the present invention. [Figure 5C] A schematic cutout of a heat sink element for a power module according to a fifth exemplary embodiment of the present invention. [Figure 6] A schematic cutout of a heat sink element for a power module according to a sixth exemplary embodiment of the present invention. [Modes for carrying out the invention]

[0070] 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 in a circuit or circuit system. For this purpose, electrical components or wire bonds are connected, for example, to the connection areas and / or conductor tracks of the component metallization 20. Structuring (not shown) ensures electrical insulation between individual metal parts in the component metallization 20. For this purpose, the structuring extends to the ceramic element 25, which acts as an insulating element for insulation between the metal parts, and the metal parts are bonded to the ceramic element 25.

[0071] The primary role of the heat sink element 1 is to effectively dissipate the heat generated during the operation of the power module 10 in the component metallization 25, thereby preventing corresponding damage to the power module 1 and ensuring that the performance of the power module 1 is not compromised or degraded. In the case of the power module 1 described herein, it is shown to be a common practice to bond a metal layer, which is bonded to the ceramic element 25 to form the component metallization 20, to the ceramic element 25 together with the back surface metallization on the opposite side of the component metallization 20 on the ceramic element 25, using a material specifically selected for the insulating element.

[0072] This serves to counteract the thermomechanical stress on the front surface of the ceramic element 25, which would otherwise result in deflection due to the different thermal expansion coefficients of the ceramic and metal. Without proper compensation, the different thermal expansion coefficients would lead to deflection of the metal-ceramic substrate, especially in the case of temperature changes during the bonding process. Therefore, proper compensation is ideally achieved when the metal layer bonded to the component surface is essentially symmetric with respect to the back surface metallization, i.e., equivalent or identical in terms of dimensions, i.e., thickness and expansion. In this way, the thermomechanical stresses acting on both sides of the ceramic element 25 essentially compensate for each other.

[0073] In conventional technology, it is common practice to bond the cooler to the corresponding backside metallization in order to ensure adequate cooling capacity for the power module 10. This is usually done by the customer and is separate from the manufacturing process of the metal-ceramic substrate. This not only results in an unwanted additional work step, but can also affect the maximum possible efficiency and cooling capacity of the heatsink element 1, and thus the overall performance of the power module 10, especially if optimal adjustments are not made.

[0074] In this case, more preferably, the heat sink element 1 is provided to be directly bonded to the ceramic element 25. In particular, it has been shown that it is possible to bond the heat sink element 1 to the ceramic element 25 without causing deflection that would render the power module 1 unusable or reduce the power efficiency of the power module 1. Specifically, the component metallization 20, the ceramic element 25, and the heat sink element 25 are each provided to extend along a plane parallel to the principal extending plane HSE and to be positioned on top of each other in a stacking direction S perpendicular to the principal extending plane HSE. The ceramic element 25 is positioned 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 along the stacking direction S. In the embodiment shown in Figure 1, the heat sink element 1 is provided to have a second thickness D2 which is greater than the first thickness D1 of the component metallization 20. In particular, when a heat sink element 1 having a second thickness D2 is bonded directly and immediately to the back surface of a ceramic element 25, such dimensional determination of the heat sink element 1 and component metallization 20 typically results in considerable deflection due to the significantly high accumulation of material on the back surface of the ceramic element 25. Surprisingly, it is possible to design the heat sink element 1 such that the deflection of the power module 10 is more than 5 times, preferably more than 8 times, and most preferably more than 10 times, less than the deflection of a reference power module having dimensions corresponding to the dimensions of the power module 10, and it is shown here that the reference power module is designed to have a solid heat sink element 1. To reduce the deflection of the power module 10 compared to a reference power module of the same dimensions, for example, multiple cooling channels 30, 30', particularly microchannel cooling channels embedded in the heat sink element 1 are provided to ensure that the corresponding deflection of the power module 10 is reduced.

[0075] In particular, for example, this has been shown to reduce deflection and allow the heat sink element 1 to be directly and immediately bonded to the back surface of the ceramic element 25. For this purpose, most preferably, for example, is provided a case in which the component metallization 20 has a first mass and the heat sink element 1 has a second mass, and the second mass deviates from the first mass by less than 160%, preferably 120% or less, and particularly preferably 80% or less. In other words, despite the significant difference 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 surface and the back surface of the ceramic element 25 are thermomechanically equivalent, for example by embedding a number of corresponding cooling channels in the heat sink element 1. The additional geometric distribution of each mass allows for the favorable induction of corresponding lever effects, which are also advantageous in compensating for corresponding deflection. Those skilled in the art will refer to corresponding empirical values ​​and / or simulations that produce corresponding mass distributions in the heat sink element 1 that have a corresponding reduction effect on the deflection of the power module 10. An exemplary design of the heat sink element 1 is shown in cross-section in Figures 5b and 5c. Further material distributions are obviously possible and are also included herein. Thus, starting from a conventional approach, it is proposed that the heat sink element 1 is bonded directly and immediately to the ceramic element 25, preferably by designing and shaping the mass distribution on the back surface of the ceramic element 25 for the heat sink element 1 to reduce deflection in a bonding process with a metal layer provided for component metallization 20. More preferably, the first expansion A1 of the component metallization 20, measured substantially parallel to the main extending surface HSE, is provided to be a certain ratio to the second expansion A2 of the heat sink element 1 extending parallel to the main extending surface HSE. More preferably, the ratio of the first expansion A1 to the second expansion A2 has a value of 0.9 to 1, more preferably 0.95 to 1, and most preferably 0.98 to 1.Therefore, it has been proven advantageous that the second expansion A2 of the heat sink element 1 is greater than the first expansion A1 of the component metallization 20, thereby minimizing the lever effect on the back surface compared to the front surface of the ceramic element 25. In particular, the manufactured metal-ceramic substrate or power module 10 is initially a master card, from which individual metal-ceramic substrates or power modules 10 are produced by cutting along predetermined fracture points, preferably using, for example, an ultrashort pulse laser. The master card is characterized in that it already has bonded heat sink elements.

[0076] Figure 2 shows a power module 10 according to a second exemplary embodiment. In particular, Figure 2 is intended to be shown as an example of possible cooling channel configurations 30, 30'. Specifically, Figure 2 shows two different possible types of cooling channels 30, 30' having two different overall flow paths. Primarily, and more preferably, the power module 10 is provided to have the same type, and in particular only one type of cooling channels 30, 30'. To illustrate the different types of cooling channels 30, they are shown by a simplified form in a common heat sink element 1 in Figure 2. The heat sink element 1 preferably has a first front S1 and a second front S2. The first front S1 and the second front S2 are opposite each other along the stacking direction S in the power module 10, and the first front S1 faces the ceramic element 25, and thus the area to be cooled. The cooling channels 30, 30' are embedded in or integrated with the base body of the heat sink element 1 and are located between the first front S1 and the second front S2. In the embodiment shown in Figure 2, the heat sink element 1 has a first opening 41 on a second front surface S2 and more preferably a second opening 42 located on the second front surface S2. A cooling medium, particularly a fluid cooling medium, is introduced into the cooling channels 30, 30' through the first opening 41, and the medium for use in cooling leaves the heat sink element 1 through the second opening 42. The cooling channels 1 preferably have a supply portion 31, a deflection portion 32, and a discharge portion 33. The supply portion 31 guides the cooling medium to the deflection portion 32 along the flow direction SR. The supply portion 31 particularly guides the cooling medium toward the first front surface S1 of the heat sink element 1. The deflection portion 32 guides the cooling medium toward the discharge portion 33 along the flow direction SR, and the discharge portion 33 more preferably guides the cooling medium toward the second opening 42, i.e., particularly toward the second front surface S2.

[0077] Furthermore, more preferably, the deflection portion 32 is provided to extend to a portion essentially parallel to the first front surface S1 of the heat sink element 1 so as to ensure the widest possible cooling. In other words, the actual cooling effect or a significant contribution to the cooling effect comes from the deflection area 32 which is more preferably located as close as possible to the ceramic element 25. More preferably, the distance A3 measured in the stacking direction S between the deflection area 33 and the ceramic element 25 is less than 250 μm, more preferably less than 150 μm, and most preferably less than 100 μm. The respective continuous flow directions SR in the supply portion 31, the deflection portion 32, and the discharge portion 33 more preferably define the overall flow path in the cooling channels 30, 30'.

[0078] In the embodiment shown on the left, the overall flow path is essentially U-shaped, while in the embodiment of the cooling channels 30, 30' shown on the right, an essentially V-shaped path is shown. Here, the flow direction SR in the supply section 31 is inclined or angled with respect to the flow direction SR in the discharge section 33, and the angle between the flow direction SR in the supply section 31 and the flow direction SR in the discharge section 33 is preferably 0° to 90°, more preferably 0° to 60°, and most preferably 0° to 45°.

[0079] In particular, it has been shown to be advantageous to control, and especially increase, the flow velocity in the deflection area 32. For this purpose, most preferably, the flow cross section is provided to be adjusted accordingly during flow along the flow path. Most preferably, it has been shown that the first flow cross section Q1 measured perpendicular to the flow direction SR in the supply section 31 is larger than the second flow cross section Q2 measured perpendicular to the flow direction SR in the deflection section 32. In the embodiment of the cooling channel 30 shown on the left of Figure 2, the respective flow cross sections are aligned perpendicular to each other due to the overall flow path. More preferably, the first flow cross section Q1 is determined in the area of ​​the first opening 41. Even more preferably, particularly in the area of ​​the second opening 42, the third flow cross section Q3 of the discharge section 33 is provided to be formed perpendicular to the flow direction SR. It has been shown that a ratio of the second flow cross section Q2 to the first flow cross section Q1 of less than 0.5, more preferably less than 0.4, and most preferably less than 0.3 is particularly advantageous, especially with respect to pressure drop through the flow path. The flow cross-section is dimensionally determined as the area limited by the respective channel walls associated with the cooling channels 30, 30'. It is also conceivable that the first flow cross-section Q1 decreases in the direction of the deflection portion 32, particularly gradually and / or continuously, and / or the third flow cross-section Q3 increases in the direction of the second opening 42, particularly continuously and / or gradually.

[0080] Furthermore, more preferably, the third flow section Q3 is provided to be larger than the second flow section Q2 and / or essentially corresponding to the first flow section Q1. By “corresponding,” those skilled in the art will understand, in particular, that the deviation between the first flow section Q1 and the third flow section Q3 is 10% or less, more preferably 5% or less, and most preferably 2.5% or less, of the average value of the first flow section Q1 and the third flow section Q3. In particular, those skilled in the art will also understand that a flow section is an area, and therefore the length of the section shown here in Figure 2 represents only a portion of the flow section considered.

[0081] Figure 3 shows a power module 10 according to a third exemplary embodiment of the present invention. In particular, the power module 10 shown herein is characterized by a heat sink element 1 in which cooling channels 30, 30' are designed to form a transverse flow portion 50. The transverse flow portion 50 is located between a second end face S2 and a deflection portion 32, and joins a supply portion 31 to a discharge portion 33, particularly upstream of the deflection portion 32, i.e., before a portion of the cooling medium reaches the deflection portion 32. This deflects a portion of the cooling medium before it reaches the deflection portion 32 and discharges it to the discharge portion. Surprisingly, this has been shown to increase the overall cooling efficiency of the power module 10. In particular, this has been shown to 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 terminates flush with the ceramic element 25 on its outer circumference, more preferably completely. This is also a preferred design for other design modifications shown in the other figures.

[0082] Figure 4 shows the arrangement of a first layer 60 and a second layer 70 positioned on top of each other along the stacking direction S to form part of the cooling channel structure in the heat sink element 1. In particular, the first layer 60 and / or the second layer 70 are provided to have web elements 61, 71. These web elements 61, 71 preferably join adjacent surface portions 62, 72 together, and most preferably, the surface portions 62, 72 of the first layer 60 and the second layer 70 positioned on top of each other are arranged congruently on top of each other, in particular to form a post portion 67 in the heat sink element 1. Such a post portion 67 is shown to be particularly advantageous because it further functions to stabilize the heat sink element 1, in particular along a direction extending parallel to the stacking direction S. In the embodiment shown in Figure 4, the surface portions 62, 72 are essentially square in their formation. It is also conceivable that circular or elliptical geometric shapes and / or rectangular and / or polygonal cross-sectional shapes may be selected. Furthermore, more preferably, the web elements 61 and 71 joining the surface portions 62 together are provided not to extend in a straight line. In the embodiment shown in Figure 4, the web elements 61 and 71 are angled, particularly forming an angle of 80° to 140°, more preferably 90° to 120°, and most preferably 90° to 100°. In other words, the connecting elements 61 and 71 comprise two sub-segments that are angled relative to each other. Alternatively, a curved path may be provided for the connecting elements 61 and 71 as a non-linear path.

[0083] Figure 4 shows top views of a first layer 60 and a second layer 70 arranged on top of each other along the stacking direction S. By appropriately dimensioning or designing the first layer 60 and the second layer 70, or by appropriately aligning the first layer 60 and the second layer 70, the web elements 61, 71 can be aligned in opposite directions. In particular, they are designed so that the web elements 61, 71 form an opening in the top view, which is confined by the web elements 61 of the first layer 60 and the web elements 71 of the second layer 70 in the observation direction extending parallel to the stacking direction S. These openings form a transverse flow portion 50. In the embodiment shown in Figure 4, this opening is designed in a diamond shape in particular. Other geometric shapes, particularly polygonal, elliptical, or circular geometric shapes, may also be designed.

[0084] The web elements 61 and 71 are understood to be, in particular, flat, continuous sub-sections in a layer extending parallel to the main extending plane, and these sub-sections have a preferred extending direction, along which the web elements 61 and 71 have an extent several times, more preferably five times or more, greater than the web width B measured perpendicular to the preferred extending direction. The surface portions 62 and 72 either do not have a preferred extending direction or have an extent along the preferred extending direction that does not exceed at most five times the web width B.

[0085] In particular, in the embodiment shown in Figure 4, the surface portions 62, 72 are arranged in a checkerboard pattern relative to each other, and each surface portion 62, 72 is provided to be joined to each adjacent surface portion 62, 72 via web elements 61, 71 on all faces, i.e., all four possible faces. Therefore, more preferably, the first layer 60 and / or the second layer 70 are designed in a grid pattern.

[0086] Figures 5a to 5c show alternative design options for the heat sink element 1 according to an exemplary embodiment. In particular, Figure 5a shows a top view of the first layer 60 and the second layer 70 arranged on top of each other along the stacking direction S. Primarily, it is assumed that the first layer 60 and the second layer 70 (which apply to the embodiment shown in Figure 4 and the embodiments shown in Figures 5a to 5c) are arranged alternately on top of each other multiple times. Alternatively, it is conceivable that a first number of first layers 60 are arranged on top of each other, and a second number of second layers 70 are arranged on top of each other, and these are also arranged on top of each other. In other words, a first number of first layers 60 are arranged via a second number of second layers 70. This makes it possible to determine the corresponding positions of the transverse flow portions 50, or to determine the number of transverse flow portions 50. The first number of the first layers 60 does not need to correspond to the second number of the second layers 70. Most preferably, the heat sink element 1 is composed of at least several, preferably five or more, particularly preferably eight or more, and most preferably ten or more individual layers, most preferably, several individual layers comprising only a first layer 60 and a second layer 70 to form a supply portion 31 and a discharge portion 33. The deflection portion is more preferably formed by a third layer 80 and / or a fourth layer (not shown) or several third layers 80 and / or fourth layers. The first layer 60, the second layer 70, the third layer 80, and / or the fourth layer differ, for example, with respect 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 the arrangement, size and / or number of surface portions 62, 72. Thus, the alternating arrangement creates an uneven inner surface of the cooling channel, which promotes turbulence of the cooling medium.

[0087] Figure 5b shows a first perspective view of a stack consisting of a first layer 60 and a second layer 70. In particular, a post portion 67 is visible here, which preferably extends from the first front surface S1 to the second front surface S2 and is especially continuously extending. It is also visible that web elements 61 and 71 positioned on top of each other form several transverse flow portions 50 positioned on top of each other. Figure 5c also shows another perspective view of the heat sink element 1. In particular, the embodiments shown in Figures 5a to 5c differ from the embodiments shown in Figure 4 in that surface portions 62 and 72 are provided that are not connected to adjacent surface portions 62, 72 in one or more directions. More preferably, the surface portions 62, 72 are joined to adjacent surface portions 62, 72 via web elements 61, 71 along a first direction, but not joined to adjacent surface portions 62, 72 along a second direction, and the first and second directions are in planes parallel to the principal extending surface HSE and are positioned at some angle to each other, especially perpendicular to each other. This is advantageous in that it defines and particularly enlarges the flow cross-section Q1 and / or third flow cross-section Q3, and correspondingly also generates a first or third flow cross-section Q1 or Q3 that is larger in the deflection section 32 compared to the second flow cross-section Q2. Most preferably, the supply section 31 and the discharge section 33 are realized by laminating corresponding individual layers, and the deflection section 32 is designed such that, for example, in the case of two adjacent cooling channels 30, 30', the discharge sections 33 are positioned adjacent to each other. In other words, the two discharge sections 33 of two adjacent cooling channels 30, 30' are located between the two supply sections 31 of the adjacent cooling channels. This is particularly advantageous because both discharge sections 33 can share a common discharge section in the distribution structure, thus facilitating the discharge of the cooling medium through the corresponding distribution structure 30, 30'. For example, the first layer 60 and the second layer 70 may also be laminated and joined at positions rotated relative to each other, preferably rotated by 180°. The first layer 60 and the second layer 70 may be offset from each other in a direction parallel to the main extending surface HSE by a distance preferably having a value of 0.01 mm to 0.5 mm, more preferably 0.01 mm to 0.25 mm, and most preferably 0.01 to 0.15 mm.

[0088] Figure 6 shows another design option for the heat sink element 1 according to an exemplary embodiment. In detail, only the first layer 60 for forming the supply portion 31 and the discharge portion 33 is laminated on top of each other. The web element 61 is formed in a straight line and bonded to the checkerboard surface portion 62. As a result, rectangular voids are created in the supply portion 31 and the discharge portion 33 that define the first and third flow cross-sections. This design is particularly advantageous because it is relatively easy to implement.

[0089] In the embodiment shown in Figure 6, several third layers 80 are provided such that one is positioned on top of the other so that their gaps, positioned on top of each other, define the deflection portion 32. The third layers 80, which are structurally identical and positioned on top of each other, are positioned relative to each other so that their gaps coincide with each other. As a result, the inner surface of the deflection area 32 is essentially smooth. It is advantageous to provide the third layers 80 offset from each other and / or a fourth layer (not shown) to create a contour on the inner surface of the deflection portion 32, or the transition from the supply portion 31 to the deflection portion 32, and / or the transition from the deflection portion 32 to the discharge portion 33. This creates targeted turbulence in areas that are particularly important for heat transfer. Preferably, the third layers 80, unlike the first layer 60 and / or second layer 70, omit one or more web elements 61 joining adjacent surface portions 62 compared to the first layer 60 and / or second layer 70, in order to create a larger recess that forms the deflection portion 32. [Explanation of Symbols]

[0090] 1 Heatsink element 10 Power Modules 20 Component Metallization 25 Ceramic elements 30,30' Cooling Channel 31 Supply part 32 Deflection part 33 Emission part 41 First opening 42 Second opening 50 Transverse flow section 60 First layer 61,71 Web elements 62,72 Surface area 67 Post section 70 Second layer 80 The third layer D1 First thickness D2 Second thickness D3 Third thickness A1 First expansion A2 Second expansion A3 distance B Web width S stacking direction S1 First side S2 Second side Q1 First flow cross section Q2 Second flow section Q3 Third flow section SR flow direction HSE main extension plane

Claims

1. A power module (10) having a heat sink element (1), Ceramic element (25) and Component metallization (20), The heat sink element (1) and the following are included: The ceramic element (25), the component metallization (20), and the heat sink element (1) each extend substantially along a plane parallel to the main extending surface (HSE), and one is positioned on top of the other in a stacking direction (S) perpendicular to the main extending surface (HSE). The ceramic element (25) is positioned between the component metallization (20) and the heat sink element (1). The component metallization (20) has a first thickness (D1) measured in the direction of travel (S), and the heat sink element (1) has a second thickness (D2) measured in the stacking direction (S). The ratio between the first thickness (D1) and the second thickness (D2) is less than 0.4, more preferably less than 0.3, and most preferably less than 0.

2. The heat sink element (1) is designed such that the deflection of the power module (10) is five times, more preferably eight times, and most preferably ten times, less than that of a reference power module having dimensions corresponding to the dimensions of the power module (10), particularly by the hollow area in the heat sink element (1), the targeted mass distribution within the heat sink element (1), or both. The aforementioned reference power module is a power module (10) having a solid heat sink element (1).

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

3. The power module (10) according to claim 1 or 2, wherein the component metallization (20) has a first mass, and the heat sink element (1) has a second mass, the second mass deviating from the first mass by 160% or less, more preferably 120% or less, and most preferably 80% or less.

4. The power module (10) according to any one of claims 1 to 3, wherein the heat sink element (1) has web elements (61, 71), and the web elements have a web width (B) which is preferably less than 250 μm, more preferably less than 200 μm, and most preferably less than 150 μm, in order to reduce deflection.

5. The power module (10) according to any one of claims 1 to 4, wherein the ceramic element (25) has a third thickness (D3) measured in the stacking direction (S), and the third thickness (D3) is a value up to 500 μm, more preferably up to 300 μm, most preferably up to 250 μm, or even further up to 200 μm.

6. The power module (10) according to any one of claims 1 to 5, wherein the heat sink element (1) defines a first volume as a body passing around its outer circumference, and occupies a second volume in the heat sink element (1) in the form of a hollow area, for example, a cooling channel (30, 30'), and the ratio of the second volume to the first volume is greater than 0.5, more preferably greater than 0.6, and most preferably greater than 0.

7.

7. The power module (10) according to any one of claims 1 to 6, wherein the heat sink element has a hollow area not intended for the flow of a cooling medium, the hollow area not intended for the flow of a cooling medium is preferably an extension of the arrangement of cooling channels (30, 30'), preferably located in the peripheral region of the heat sink element (1), or both.

8. The heat sink element (1) is A base body having a first front surface (S1) facing the area to be cooled during installation, and a second front surface (S2) on the opposite side from the first front surface (S1), The present invention further comprises a cooling channel (30, 30') embedded in the base body between the first front surface (S1) and the second front surface (S2), The cooling channel (30, 30') has a supply portion (31), a deflection portion (32), and a discharge portion (33), The cooling channels (30, 30') are designed to form an overall flow path in the supply section (31) for transporting the cooling medium toward the first front surface (S1), to transfer the cooling medium to the discharge section (33) in the deflection section (32), and to transport the cooling medium toward the second front surface (S2) in the discharge section (33). The power module (10) according to any one of claims 1 to 7, wherein the supply portion (31) has a first flow cross section (Q1) measured perpendicular to the flow direction (S), and the deflection portion (32) has a second flow cross section (Q2) measured perpendicular to the flow direction (S), and the ratio of the second flow cross section (Q2) to the first flow cross section (Q1) is less than 0.5, more preferably less than 0.4, and most preferably less than 0.

3.

9. The 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 each other.

10. A first opening (41) is formed in the supply portion (31) of the second end face (S2), The heat sink element (1) according to any one of claims 1 to 9, wherein the flow cross section measured perpendicular to the flow direction (SR) at the first opening (41) is different from the first flow cross section (Q1) at the downstream portion of the supply portion (31) by less than 15%, more preferably less than 10%, and most preferably less than 5%.

11. A heat sink element (1) according to any one of claims 1 to 10, wherein there is exactly one transverse flow portion (50) for each cooling channel (30, 30').

12. The heat sink element (1) is either directly bonded to a ceramic element (25), or the distance between the deflection portion (32) and the ceramic element (25) is less than 300 μm, more preferably less than 200 μm, and most preferably less than 100 μm, according to any one of claims 1 to 11.

13. The heat sink element (1) is surrounded on the first front surface (S1) and is the heat sink element (1) according to any one of items 1 to 12.

14. The heat sink element (1) is A base body having a first front surface (S1) facing the area to be cooled during installation, and a second front surface (S2) on the opposite side from the first front surface (S1), The device comprises a cooling channel (30, 30') embedded in the base body between the first front surface (S1) and the second front surface (S2), The cooling channel (30, 30') has a supply portion (31), a deflection portion (32), and a discharge portion (33), The cooling channels (30, 30') are designed to form an overall flow path in the supply section (31) for transporting the cooling medium toward the first front surface (S1), to transfer the cooling medium to the discharge section (33) in the deflection section (32), and to transport the cooling medium toward the second front surface (S2) in the discharge section (33). The power module (10) according to any one of claims 1 to 13, wherein one or more transverse flow portions (50) joining the supply portion (31) and the discharge portion (33) are formed between the deflection portion (32) and the second front surface (S2).

15. A method for manufacturing a power module (10) according to any one of claims 1 to 14, wherein the heat sink element (1), the metal layer for component metallization (20), and the ceramic element (25) are preferably connected to each other in a common bonding step.

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