Support element for electrical components and method for manufacturing such a support element

Description

[0001] The present invention relates to a support element for electrical components and a method for manufacturing such a support element.

[0002] Heat sinks for cooling electrical and electronic components, especially semiconductors such as laser diodes, are well-known in the art. During operation, these components generate heat, which is dissipated by the heat sink to ensure their continued functionality. This is particularly important for laser diodes, where even temperature differences of just a few degrees Celsius can significantly impair performance and / or lifespan.

[0003] To cool the components, the heat sinks, which are usually attached to the components, typically have a cooling fluid channel system through which a cooling fluid is circulated during operation to absorb and dissipate heat emanating from the electrical or electronic component. Preferably, a fin structure is used in which several rib-like elements project into the cooling fluid channel system to provide the largest possible contact area with the cooling fluid, thereby improving the heat transfer from the walls that delimit the cooling fluid channel system to the cooling fluid.

[0004] Furthermore, it is common to use heat sinks to cool printed circuit boards that are designed as metal-ceramic substrates.

[0005] For high thermal conductivity, metals are typically used to form the cooling structure. However, these are susceptible to corrosion when continuously exposed to a coolant. To protect against corrosion, it is common practice to apply a nickel coating.

[0006] From CN 102 208 377 A it is further known to coat a cooling sink with fins with a SiO2 layer. However, the teaching relates to a one-piece cooling sink.

[0007] DE 10 2020 104 493 A1 describes the manufacture of a heat sink from several layers with recesses. DE 10 2018 112 000 A1 relates to a distribution structure with which a cooling fluid is introduced into individual cooling channels in a heat sink. WO 2009 052817 A2 describes a corrosion protection for microchannel heat sinks.

[0008] The present invention aims to improve the service life and manufacturing of corrosion protection for certain cooling elements.

[0009] This problem is solved by the support element according to claim 1 and by the method according to claim 9. Further advantages and features of the invention will become apparent from the dependent claims, the description, and the accompanying figures.

[0010] According to a first aspect of the present invention, a support element for electrical components is provided, wherein the support element comprises a metallic heat sink for dissipating heat emanating from the electrical component during its operation, the heat sink having a metal granulation with an average grain size, the average grain size being in the range between 10 µm and 800 µm, preferably between 100 µm and 700 µm, and particularly preferably between 300 and 600 µm, wherein the heat sink comprises at least a portion of an oxide-containing corrosion protection layer. For this purpose, the line-cutting method described, for example, in ASTM 112-13 is used.

[0011] The present invention takes advantage of the fact that the heat sink incorporates metal granules with an average grain size between 10 µm and 800 µm, preferably between 100 µm and 700 µm, and particularly preferably between 300 µm and 600 µm. This automatically provides a surface roughness that advantageously improves the adhesion of the corrosion protection layer to the cooling structure or heat sink. The corrosion protection layer is applied to the outer surface of the heat sink, which is in contact with the coolant. This prevents the heat sink and / or the cooling system or components within the cooling system from corroding over time, thereby significantly increasing the service life of the heat sink and / or the cooling system or components within the cooling system.Furthermore, the grain size, particularly in the range between 300 µm and 600 µm, proves advantageous in that it improves, or rather reduces, the thermal resistance at the interface between the coolant and the outer surface of the heat sink coated with the corrosion protection layer. This compensates for the increase in thermal resistance that is inevitable when using a corrosion protection layer. Consequently, it is advantageously possible to apply the corrosion protection layer without significantly impairing the heat transfer from the cooling structure to the coolant.

[0012] Preferably, the desired grain size distribution or particle size distribution in the heat sink is achieved through the manufacturing process or a bonding process of the heat sink. In particular, the cooling structure is exposed to a temperature higher than 600 °C, preferably higher than 800 °C, and most preferably higher than 1000 °C. This initiates a corresponding grain formation or crystallization, resulting in the desired particle size distribution, which has proven particularly advantageous in conjunction with the applied corrosion protection layer. Therefore, a desired grain size distribution cannot be automatically assumed for every metallic heat sink.

[0013] The grain sizes are determined using a line sectioning method. Line sectioning methods are known to those skilled in the art and are described, for example, in ASTM 112-13. Preferably, a microscopic image of the surface of the heat sink is taken. The magnification is selected such that at least 100 grains are intersected by the line grid.

[0014] For example, two parallel lines in the x-direction and two parallel lines in the y-direction are placed in the image. These lines divide the image into three equally wide strips. When a grain is intersected by one of these lines over a certain length, this length L is taken as the grain size. A grain size is thus obtained for each grain intersected by one of these lines. At the intersection of two lines, two values ​​are obtained for a single grain, both of which are used to determine the grain size distribution.

[0015] Preferably, the heat sink is composed of at least a first metal layer and a second metal layer. It is preferably provided that the first and second metal layers have recesses which, in the assembled, and in particular stacked, state of the first and second metal layers, overlap at least partially or are arranged one above the other along a stacking direction. This creates a portion of a microchannel through the recesses, which are at least partially congruent. It is conceivable that the first and second metal layers are offset from each other, resulting in a stepped channel interior in the area of ​​the channel formed in the manufactured state. In principle, a heat sink consists of a plurality of first and second metal layers stacked on top of each other.These stacked first and second metal layers can then be joined together, for example, by means of a direct bonding process, a diffusion bonding process or a soldering process, so that a preferably one-piece body is created.

[0016] This heat sink then exhibits a corresponding or specified grain size due to the temperatures used during the bonding process, provided that suitable starting materials for the first and second metal layers and / or a suitable temperature profile were used during bonding. A person skilled in the art would ensure a corresponding purity of the first and / or second metal layer to achieve the desired grain sizes. Preferably, the stacked and bonded first and second metal layers provide a microchannel system, which is preferably designed to cool an electrical component, in particular a laser diode and / or power transistor, which is connected directly to the heat sink or to the heat sink via an adapter element.

[0017] Preferably, the support element comprises a metal-ceramic substrate. It is conceivable that the heat sink is directly connected to a ceramic element of the metal-ceramic substrate and / or to a back-side metallization facing a component metallization. The component metallization and back-side metallization are preferably connected to opposite sides of the ceramic element to form the metal-ceramic substrate. Such metal-ceramic substrates prove to be particularly sensitive to heat generation from the electrical components on the component side, since thermomechanical stresses can easily be generated due to the different coefficients of thermal expansion. These stresses can lead to bending of the entire support element or to a breakdown of the bond between the ceramic element and the metal layer.Therefore, it is crucial for such metal-ceramic substrates that the thermal resistance of the overall system, particularly at the interface between the heat sink and the coolant, is not increased. For this reason, it is especially advantageous to provide a suitable corrosion protection layer.

[0018] It is particularly preferred that the corrosion protection layer comprises SiO₂, TiO₂, Al₂O₃, ZrO, CaO, K₂O, and / or ZnO. A corrosion protection layer made of silicon dioxide, i.e., SiO₂, has proven particularly advantageous, making it possible to provide up to 1000 times greater corrosion protection, which significantly extends the service life of the manufactured heat sink. Preferably, the corrosion protection layer is free of nanoparticles. Furthermore, it is advantageous that the silicon dioxide-containing corrosion protection layer allows for an increase in the permissible flow velocity within the cooling structure, i.e., in the cooling channels, thereby improving cooling performance. It also promotes electrical insulation of the cooling channel.

[0019] Preferably, the corrosion protection layer has a thickness of less than 3 µm, preferably less than 1000 nm, and particularly preferably less than 500 nm. More preferably, the thickness of the corrosion protection layer is greater than 20 nm, more preferably greater than 80 nm, and particularly preferably greater than 250 nm. In particular, it is preferred that the thickness be between 20 nm and 1000 nm, more preferably between 100 nm and 750 nm, and particularly preferably between 250 nm and 500 nm. Such thin corrosion protection layers prove to be particularly advantageous because, for example, they do not contribute to the formation of a microchannel or corresponding structure in the heat sink being clogged by the corrosion protection layer.Furthermore, the generated thermal resistance depends on the thickness of the applied corrosion protection layer. Therefore, using appropriately thin corrosion protection layers can prevent excessive thermal resistance from forming between the heat sink and the coolant. For such protective layers with thicknesses in the range of 1 µm to 3 µm, it is advantageous that they can be produced relatively easily using a sol-gel process. Corrosion protection layer thicknesses below 500 nm can preferably be achieved by gaseous deposition, for example, by sputtering. It is particularly advantageous that this allows for a homogeneous distribution of the corrosion protection layer thickness, i.e., the thickness of the corrosion protection layer is as constant as possible. In other words, the thickness of the corrosion protection layer is constant over its entire extent.There are no deviations from the mean value of the corrosion protection layer thickness that are greater than 15%, preferably greater than 10%, and particularly preferably greater than 5% of the determined mean value.

[0020] Preferably, the metal-ceramic substrate is designed as a printed circuit board (PCB) in which, in the manufactured state, the at least one metal layer bonded to the ceramic element is structured. For example, it is provided that, after the bonding step, structuring is also carried out, for example by laser treatment, etching, and / or mechanical processing, with which conductive traces and / or connections for electrical or electronic components are realized. Preferably, it is provided that, on a manufactured metal-ceramic substrate, on the ceramic element on the side opposite the metal layer, a further metal layer, in particular a back-side metallization, and / or a cooling element, is provided. The back-side metallization preferably serves to counteract deflection, and the cooling element serves to effectively dissipate heat generated during the operation of electrical or electronic components.originates from electronic components that are connected to the circuit board or the metal-ceramic substrate.

[0021] Possible materials for the at least one metal layer and / or the at least one further metal layer in the metal-ceramic substrate or ceramic element 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. Furthermore, it is preferably provided that the at least one metal layer on the manufactured metal-ceramic substrate, particularly as component metallization, is surface-modified. Surface modification could, for example, involve sealing with a precious metal, particularly silver; and / or gold, or (electroless) nickel or ENIG (electrolyte alloy). electroless nickel immersion gold ") or edge sealing on the metallization to suppress crack formation or widening is conceivable.

[0022] Preferably, the ceramic element comprises Al₂O₃, Si₃N₄, AIN, an HPSX ceramic (i.e., a ceramic with an Al₂O₃ matrix containing an x ​​percent ZrO₂, for example, Al₂O₃ with 9% ZrO₂ = HPS9 or Al₂O₃ with 25% ZrO₂ = HPS25), SiC, BeO, MgO, high-density MgO (> 90% of the theoretical density), or TSZ (tetragonally stabilized zirconia) as the ceramic material. It is also conceivable that the ceramic element is designed as a composite or hybrid ceramic, in which several ceramic layers, each differing in their material composition, are arranged one above the other and joined together to form a ceramic element in order to combine various desired properties.

[0023] Preferably, a gap is provided between opposing side walls of the at least one first metal layer, The thickness of the gap is at least partially smaller than 0.4 mm, preferably smaller than 0.3 mm, and particularly preferably smaller than 0.2 mm, or assumes a value between 0.5 mm and 2.5 mm, preferably between 0.7 mm and 1.5 mm, and particularly preferably between 0.8 mm and 1.2 mm. Such thin gaps, with distances smaller than 0.2 mm, are particularly susceptible to blockages, making a correspondingly thin application of a corrosion protection layer advantageous. However, the method also proves advantageous for cooling channels with a larger cross-section or larger opening.

[0024] Furthermore, it is preferred that the heat sink be made of copper and / or aluminum.

[0025] A further object of the present invention is a method for producing a support element according to the invention, wherein the heat sink is exposed to a temperature above 600 °C, preferably above 800 °C and particularly preferably above 1000 °C, for its formation and / or for bonding to a metal layer and / or to a ceramic element. The metal layer to which the heat sink is bonded is preferably the back-side metallization of the metal-ceramic substrate. It is also conceivable that the heat sink is bonded directly to the ceramic element, in particular to its cooling side. The properties and advantages described for the support element can be transferred analogously to the method.

[0026] It is conceivable that the corrosion protection layer is bonded to the inside of the cooling channel at a temperature between 100 °C and 500 °C, preferably between 200 °C and 400 °C, and particularly preferably between 250 °C and 350 °C. Preferably, residual heat after the bonding process of the individual layers is used to cure the corrosion protection layer.

[0027] Preferably, the corrosion protection layer is applied to the heat sink by means of gaseous deposition. Alternatively, it is conceivable that the corrosion protection layer is applied using a sol-gel process. Furthermore, it is conceivable that the gaseous deposition of the first and second metal layers takes place prior to the bonding process. For example, corresponding gaps are temporarily coated with the corrosion protection layer by means of gaseous deposition, and after the application of the corrosion protection layer, the bonding of at least the first metal layer to the at least second metal layer takes place. It is conceivable that at least some of the applied corrosion protection layer is subsequently removed, particularly in the area where a bond between the first and second metal layers is to be established.Alternatively, it is conceivable that the corrosion protection layer could be applied after the bonding process has been carried out. This proves particularly advantageous because the grain size, which has proven beneficial for the adhesion of the corrosion protection layer to the cooling structure, is already established.

[0028] Furthermore, it is preferably provided that the at least one metal layer and / or the at least one further metal layer is bonded to the ceramic element by means of an active soldering process and / or a hot isostatic pressing process and / or a DCB process.

[0029] For example, a process for producing a metal-ceramic substrate is provided, comprising: Providing a solder layer, in particular in the form of at least one solder foil or hard solder foil, coating the ceramic element and / or the at least one metal layer and / or the at least one solder layer with at least one active metal layer, arranging the at least one solder layer between the ceramic element and the at least one metal layer along a stacking direction to form a soldering system comprising the at least one solder layer and the at least one active metal layer, wherein a solder material of the at least one solder layer is preferably free of a melting point-lowering material or of a phosphorus-free material, and bonding the at least one metal layer to the at least one ceramic layer via the soldering system by means of an active soldering process.

[0030] In particular, a multilayer soldering system is provided, consisting of at least one solder layer, preferably free of melting-point-lowering elements, and especially preferably a phosphorus-free solder layer, and at least one active metal layer. The separation of the at least one active metal layer and the at least one solder layer proves particularly advantageous because it allows for the realization of comparatively thin solder layers, especially when the solder layer is a foil. Otherwise, for solder materials containing active metals, comparatively large solder layer thicknesses must be achieved due to the brittle intermetallic phases or the high modulus of elasticity and high yield strength of common active metals and their intermetallic phases, which hinder the deformation of the solder paste or solder layer. This limits the minimum layer thickness to the manufacturing properties of the solder material containing active metals.Accordingly, for solder layers containing active metals, the minimum thickness of the solder layer is not determined by the minimum thickness required for the joining process, but rather by the technically achievable minimum thickness. This makes the thicker, active-metal-containing solder layer more expensive than thinner layers. The term "phosphorus-free" means, in particular, that the proportion of phosphorus in the solder layer is less than 150 ppm, less than 100 ppm, and especially preferably less than 50 ppm.

[0031] Preferably, the solder layer, in particular the phosphorus-free solder layer, comprises several materials in addition to the pure metal. For example, indium is a component of the solder material used in the solder layer.

[0032] Furthermore, it is conceivable that the solder material for forming the solder layer is applied to the active metal layer and / or the at least one metal layer by physical and / or chemical vapor deposition and / or electroplating. This advantageously makes it possible to achieve comparatively thin solder layers in the soldering system, particularly with a homogeneous distribution.

[0033] For example, the production of the metal-ceramic substrate, in particular the metal-ceramic substrate, involves further steps, including: - providing a ceramic element and a metal layer, Providing a gas-tight container that encloses the ceramic element, wherein the container is preferably formed from or comprises the metal layer, forming the metal-ceramic substrate by bonding the metal layer to the ceramic element by means of hot isostatic pressing, In order to form the metal-ceramic substrate, an active metal layer or a contact layer comprising an active metal is arranged at least section by section between the metal layer and the ceramic element to support the bonding of the metal layer to the ceramic element. The container is preferably formed as a metal container consisting of one metal layer and / or another metal layer. Alternatively, it is also conceivable that a glass container is used.

[0034] In hot isostatic pressing, bonding is achieved by heating under pressure, ensuring that the first and / or second metal layer of the metal container, particularly the subsequent metal layer of the metal-ceramic substrate and any eutectic layer present there, does not melt. Accordingly, hot isostatic pressing requires lower temperatures than direct metal bonding (DCB) processes.

[0035] Further advantages and properties will become apparent from the following description of preferred embodiments of the invention with reference to the accompanying figures. These show: Fig. 1 :schematic exploded view of a support element for an exemplary embodiment of the present invention, Fig. 2 schematic representation of a first metal layer for a heat sink made of Figure 1 , Fig. 3 schematic representation of a support element for a further exemplary embodiment of the present invention, Figs. 4 to 8 :detailed representation of a system consisting of the carrier element with a distribution structure and Fig. 9 Schematic representation of a corrosion protection layer on a cooling sink

[0036] In Figure 1Figure 1 is a schematic exploded view of a heat sink 1 according to a first preferred embodiment of the present invention. In particular, the heat sink 1 is designed for cooling an electronic or electrical component (not shown), especially a semiconductor element and, more preferably, a laser diode. For cooling the electrical or electronic component, the manufactured heat sink 1 forms a cooling fluid channel system through which a cooling fluid can flow during operation, so that the cooling fluid can absorb and dissipate heat emitted by the electronic or electrical component during operation.

[0037] For this purpose, the cooling element 1, particularly the cooling fluid channel system, preferably includes an inlet area and an outlet area (not shown), wherein the cooling fluid is introduced via the inlet area and discharged again via the outlet area. Preferably, the cooling fluid channel system is designed such that the cooling fluid 1 passes through a fin structure 25 at the transition from the inlet area to the outlet area, which in particular projects into the cooling fluid channel system. The fin structure 25 preferably consists of rib-like elements 7 that project into the cooling fluid channel system in order to provide the largest possible contact area for the fluid, thus enabling effective heat transfer from the rib-like element 7 or the wall of the cooling channel system to the fluid.

[0038] Preferably, the heat sink 1 comprises at least one first metal layer 11, at least one second metal layer 12 and / or at least one third metal layer 13. To form the cooling fluid channel system, the at least one first metal layer 11, the at least second metal layer 12 and / or the at least third metal layer 13 are structured by at least one recess 21, 22 such that they form the cooling fluid channel system by being stacked on top of each other or placed one above the other along the stacking direction S.

[0039] It is specifically provided that the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 each have a different structure or are equipped with differently oriented recesses 21, 22. In particular, it is provided that the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 form at least one first part 21 in the at least one recess 21, 22, which has the web-like elements 7 that extend, in particular, in a principal extension plane HSE perpendicular to the stacking direction S.In addition to the first part 21 of the at least one recess 21, 22 in the at least one first metal layer 11, it is preferably provided that a second part 22 of the at least one recess 21, 22 in the at least one first metal layer 11 is provided for supplying or discharging the cooling fluid into or out of the first part 21 or forms a part of the supply area and / or discharge area.

[0040] The heat sink 1 is preferably bounded in the stacking direction S by an upper cover layer 15 and a lower cover layer 14, wherein the first, at least one, metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 are arranged between the lower cover layer 14 and the upper cover layer 15 in the stacking direction S. In particular, the formation of the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 is arranged in a sandwich-like configuration between the upper cover layer 15 and the lower cover layer 14. In addition to the at least one recess 21, 22, which is composed of the first part 21 and the second part 22, it is preferably provided that the heat sink 1 or the at least one first metal layer 11 has a further recess 24, which is not part of the cooling fluid channel system with the fin structure 25.Furthermore, it is preferably provided that a connection surface 30 is provided on the upper cover layer 15 and / or the lower cover layer 14. In particular, the electrical or electronic component is connected to this connection surface 30, especially when viewed in the stacking direction S, above or below the fin structure 25, which preferably extends in a direction perpendicular to the stacking direction S. In other words, the fin structure 25, in particular its rib-like elements 7, extends below the connection surface 30 and preferably parallel to it. By appropriately arranging the fin structure 25 with its rib-like elements 7 above or below the connection surface 30, the electrical or electronic component can be effectively cooled by means of the fin structure 25.

[0041] In Figure 2is a schematic representation of at least one first metal layer 11, which is shown, for example, in Figure 1The fin structure 25 is installed in the illustrated embodiment. It is formed from rib-like elements 7 that extend to different distances in the main extension plane HSE. In particular, the length of the rib-like elements 7 increases towards a central axis M of the at least one first metal layer 11. This advantageously maximizes the cooling effect, especially in the central region of the contact surface 30. Furthermore, it is conceivable that the rib-like elements run parallel and / or obliquely to the central axis M. Preferably, the shape of the rib-like elements 7, in particular their length and / or inclination relative to the central axis M along the main extension plane HSE, is determined or specified by the corresponding cooling requirements of the electrical or electronic component.

[0042] To achieve the smallest possible distance A1 between two adjacent rib-like elements 7, it is provided, for example, that the first part 21 of the at least one recess 21, 22 in the at least one first metal layer 11 is produced by electrical discharge machining (EDM), in particular by spark EDM. Specifically, this involves production by wire EDM.

[0043] Furthermore, it is provided that a second part 22 of the at least one recess 21, 22 is formed by etching. Preferably, the etching is carried out particularly in large areas of the second part 22 of the recess 21, 22, i.e., in the subsequent inlet and / or outlet areas designed for supplying and discharging the cooling fluid. In contrast, it is particularly provided that electrical discharge machining (EDM) is used for the fine-structured forming of the recess 21, 22, i.e., the first part 21 of the recess 21, 22. It has been found that this allows comparatively very small gaps between the rib-like elements 7 to be produced without having to rely on several first metal layers 11 with etched first parts 21 of the at least one recess 21, 22, which would have to be stacked on top of each other to achieve the smallest possible gap between two rib-like elements 7.Preferably, the distance A1 between opposing side walls between two rib-like elements 7 is less than 0.4 mm, more preferably less than 0.3 mm, and particularly preferably less than 0.2 mm. This allows as many rib-like elements 7 as possible to be integrated into the fin structure 25. Accordingly, it is possible to increase the cooling effect, since the contact area between the cooling fluid and the surface of the cooling fluid channel system can be increased accordingly.

[0044] Preferably, the at least one first metal layer 11, the at least one second metal layer 12, the at least one third metal layer 13, the upper cover layer 15 and / or the lower cover layer 14 have a thickness, measured in the stacking direction S, of between 0.2 and 0.7 mm, preferably between 0.35 and 0.6 mm, and particularly preferably between 0.3 and 0.4 mm. Preferably, the at least one first metal layer 11, the at least one second metal layer 12 and / or the at least one third metal layer 13 each have the same thickness.Furthermore, it is preferably provided that the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 are formed into an integral cooling fluid channel system by means of a sintering process in which the microstructures of the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 merge or fuse together through a corresponding heat treatment. It is further provided that the upper cover layer 15 and / or the lower cover layer 14 each have at least one recess 21, 22, and / or a further recess 24, wherein the upper cover layer 15 and / or the lower cover layer 14 are preferably free of rib-like elements 7 or components of a subsequent fin structure 25. The further recesses 24 preferably serve for fastening or fixing the cooling element 1.

[0045] In Figure 3A metal-ceramic substrate 70 according to a further exemplary embodiment of the present invention is shown schematically. Such metal-ceramic substrates 1 preferably serve as carriers for electronic or electrical components 4, which can be bonded to the metal-ceramic substrate 70. Essential components of such a metal-ceramic substrate 1 are a ceramic element 71 extending along a principal extension plane HSE and a component metallization 72 bonded to the ceramic layer 71. The ceramic element 71 is made of at least one material comprising a ceramic. The component metallization 72 and the ceramic element are arranged one above the other along a stacking direction S extending perpendicular to the principal extension plane HSE and are metallurgically bonded to one another.In the manufactured state, the component metallization 72 on one component side 5 of the metal-ceramic substrate 70 is structured to form conductive tracks or connection points for the electrical components 4. In the illustrated embodiment, the metal-ceramic substrate 70 comprises a secondary layer 73 and a metallic intermediate layer 75 arranged between the ceramic element 71 and the secondary layer 73. The ceramic element 71, the metallic intermediate layer 75, and the secondary layer 73 are arranged one above the other along the stacking direction S. Furthermore, it is provided that the metallic intermediate layer 75 is thicker than the ceramic element 71 and / or the secondary layer 73. Preferably, the metallic intermediate layer 75 is thicker than 1 mm, more preferably thicker than 1.5 mm, and particularly preferably thicker than 2.5 mm.However, it is also conceivable that the metal-ceramic substrate is formed using only a ceramic element 71 with a component metallization 72 and a backside metallization. While the ceramic element 71 is preferably made of ceramic and designed to provide sufficient insulation strength and to stiffen the metal-ceramic substrate 1, the secondary layer 73 can, for example, also be made of tungsten or molybdenum, since a high degree of insulation strength is not required here. This reduces material costs. Alternatively, the secondary layer 73 is also made of a material comprising a ceramic.

[0046] A metallic heat sink 20 is provided on one of the cooling sides 6 of the metal-ceramic substrate 1, opposite the component side 5. The metallic heat sink 20 is preferably directly connected to the secondary layer 73. However, it is also conceivable that the heat sink 20 is directly connected to a back-side metallization of the metal-ceramic substrate 1 or to the ceramic element 71 of the metal-ceramic substrate 1. This prevents an interface that would otherwise form with a corresponding bonding material from negatively affecting the thermal conductivity and thus restricting heat transfer from component side 5 to the cooling side 6.

[0047] For example, the cooling structure 20 is directly bonded to the secondary layer 73, the backside metallization, and / or the ceramic element 71 via an AMB process, a DCB (direct copper bonding) or DAB (direct aluminum bonding) process. In particular, a multitude of fluid channels 30 are integrated into the metallic cooling structure 20. For clarity, Figure 1 Only one of these fluid channels 30 is shown as an example. The fluid channels 30 serve to guide a fluid, in particular a cooling fluid, within the metallic cooling structure 20. The fluid is supplied to the cooling structure 20 via a distribution structure 40 and discharged again via the distribution structure 40. Preferably, the distribution structure 40 has an inlet section 41 and a discharge section 42 for this purpose.

[0048] In particular, the fluid channel 30 has an inlet opening 31 and an outlet opening 32 spaced apart from the inlet opening 31. The inlet opening 31 and the outlet opening 32 are part of an outer surface A of the cooling structure 20 facing the distribution structure 40. Specifically, the inlet part 31 of the distribution structure 40 borders the inlet opening 31 and the outlet part 42 borders the outlet opening 32.

[0049] In the Figures 4 to 6 Only the metallic cooling structure 20 and the distribution structure 40 are shown in perspective views and in the Figure 7 and 8The figures are shown in two different side views. Instead of the entire cooling structure 20, the figures depict the multiple fluid channels 30 of the cooling structure 20. In other words, the fluid channels 30 are shown here without the metallic body in which they are embedded. Viewed in the stacking direction S, a feed structure 50 is also connected to the underside of the distribution structure 40. Thus, viewed in the stacking direction S, the distribution structure is arranged between the cooling structure and the feed structure. Such a feed structure 50 is preferably designed to define a first main flow direction HS1. For example, the feed structure is channel-shaped. Furthermore, the feed structure 50 includes at least one inlet and one outlet (not shown here) to which a fluid circuit can be connected, i.e., a cooling fluid supply and a cooling fluid discharge.The distribution structure 40 is preferably configured such that it deflects or introduces the fluid from a flow along the first main flow direction HS1 into the cooling structure 20. For the sake of clarity, the figures show only a single row of fluid channels 30. Preferably, several rows are arranged side by side or one behind the other in a direction perpendicular to the row direction RR and parallel to the main extension plane HSE, and each of these rows is supplied with the fluid via a corresponding distribution structure 40, for example, a single distribution structure. Preferably, these multiple rows extend completely over the outer surface A of the cooling structure 20 facing the distribution structure.

[0050] In particular, it is provided that several fluid channels 30 are arranged side by side. Specifically, in the illustrated embodiment, the fluid channels 30 are arranged along a row which, in the illustrated embodiment, runs essentially perpendicular to the first main flow direction HS1. It is also conceivable that the row runs along a row direction RR which is inclined at an angle between 0° and 90° relative to the first main flow direction HS1. Preferably, the angle is less than 45°.

[0051] In the Figures 4 to 8In the illustrated embodiment, the distribution structure 40 is designed to deflect the fluid such that at least a portion of the fluid is first deflected from a first main flow direction HS1 into a transverse direction Q parallel to the series direction before being directed into the inlet openings 31. Additionally, the fluid is deflected upwards towards the cooling structure 20 in the direction of the inlet opening 31. This allows the distribution structure to supply several inlet openings 31 of different fluid channels 30 with a fluid at the same temperature. For this purpose, the inlet section 41 is designed as a wall-like structure, which in the illustrated embodiment runs essentially parallel to the series direction RR. Preferably, the feed structure 50 supplies the fluid to only a portion of the distribution structure 40.In the illustrated embodiment, along the first main flow direction HS1, essentially a first part, in particular a left half, of the inlet section 41 is supplied with the cooling fluid. However, the entire series of fluid channels 30 is supplied with the fluid by means of the distribution structure 40. Preferably, the inlet section comprises a ramp-like structure that is inclined in the series direction RR, in particular with respect to the main extension plane HSE.

[0052] After passing through the fluid channels 30, the fluid exits the cooling structure 20 via the outlet openings 32 and is directed into the discharge section 42 of the distribution structure. The discharge section 42 of the distribution structure 40 is also designed as a wall-like structure that runs essentially parallel to the series direction RR. In particular, the discharge section 42 is designed to collect the fluid exiting the outlet openings and redirect it back into the feed structure 50 in a second main flow direction HS2. For example, the discharge section 42 includes a ramp-like structure inclined in the series direction RR, in particular inclined in the opposite direction to the ramp-like structure in the inlet section 41 of the distribution structure 40. Furthermore, the first main flow direction HS1 and the second main flow direction HS2 are offset from each other.In other words, after leaving the distribution structure 40, the flow of the fluid is laterally displaced compared to the flow when approaching the distribution structure 40.

[0053] In the illustrated embodiment, the inlet part 41 of the distribution structure 40 is arranged upstream of the outlet part 42 of the distribution structure 40 when viewed along the first main flow direction HS1. However, it is also conceivable that the outlet part 42 is arranged upstream of the inlet part 31 of the distribution structure 40 when viewed along the first main flow direction HS1.

[0054] The individual fluid channels 30 are preferably U-shaped, with the U-shaped fluid channel 30 having two leg regions 34 extending substantially perpendicular to the main extension plane HSE and a transverse region 33 connecting the two leg regions 34. In particular, the transverse region 33 serves to deflect the fluid and, in the installed state, is closest to the secondary layer 13 or the ceramic layer 11. Preferably, the distance between the transverse region 33 and a ceramic layer 11 or secondary layer 13 adjacent to the cooling structure 20 is between 0.2 and 1.5 mm, more preferably between 0.4 and 1 mm, and most preferably between 0.6 and 0.8 mm. Preferably, the fluid channels 30, and in particular their leg regions 34, are designed such that the fluid is swirled within the fluid channels 30.For this purpose, it is provided, for example, that an opening cross-section Q1, Q2 of the leg sections 34, extending parallel to the main extension plane HSE, is laterally displaced along a flow direction of the fluid within the fluid channel 30, particularly within the leg section 34. The leg section 34 comprises a first subsection T1 with a first opening cross-section Q1 and a second subsection T2 with a second opening cross-section Q2, wherein the first opening cross-section Q1 is offset from the second opening cross-section Q2 by an offset distance V in a direction parallel to the main extension plane HSE. Preferably, the first opening cross-section Q1 and the second opening cross-section Q2 are of the same size. However, it is also conceivable that the first opening cross-section differs from the second opening cross-section.In particular, the first subsection T1 and the second subsection T2 are each assigned metal layers, which are stacked on top of each other, for example, during manufacturing. The individual metal layers can be of the same thickness or differ in thickness. It is also conceivable, for example, that the thickness of the individual layers decreases and / or increases towards the side of the component.

[0055] In particular, it is provided that the first opening cross-section Q1 and the second opening cross-section Q2 are offset from each other in two directions: one parallel to the first main flow direction HS1 and the other parallel to the series direction RR, i.e., in two directions that are not parallel to each other. Preferably, the ratio of an overlap area, in which the first opening cross-section Q1 and the second opening cross-section Q2 are arranged one above the other in the stacking direction S, to the first opening cross-section Q1 and the second opening cross-section Q2 is between 0.5 and 0.9, preferably between 0.5 and 0.8, and most preferably between 0.5 and 0.7. It is particularly conceivable that the opening cross-section of the inlet opening and / or the outlet opening is larger than the first opening cross-section and / or the second opening cross-section.This allows a funnel-shaped inlet and outlet area to be formed for the fluid channel.

[0056] It is also conceivable that the first opening cross-section Q1 and the second opening cross-section Q2 are of different sizes. Preferably, the first and second opening cross-sections are designed such that they form an essentially spiral path for the fluid channel 30. The fluid channels 30 can be realized, for example, by layering metal layers, i.e., at least a first metal layer 11 and a second metal layer 12, with corresponding openings, or by a 3D printing process. Furthermore, it is provided that the inlet opening 13 has a first opening cross-section whose diameter and / or edge length has a value between 0.1 mm and 2.5 mm, preferably between 0.5 mm and 1.5 mm, and preferably substantially 1 mm. It is preferably provided that the first opening cross-section Q1 and the second opening cross-section Q2 do not change within the leg regions 34 of the fluid channel 30.

[0057] Furthermore, it is provided that a further distance A2 between two adjacent leg sections, preferably of the same fluid channel, assumes a value between 0.1 mm and 5 mm, preferably between 0.2 mm and 2 mm, and particularly preferably substantially 1.5 mm. The further distance A2 is measured between two centers of the first cross-sectional opening Q1 or second cross-sectional openings Q2 at the same height, viewed in the stacking direction S.

[0058] In addition to the heat sinks 20 and support elements 1 described above, other heat sinks 20 with different geometries are also conceivable. For example, it is even possible for the heat sink 20 to be formed from a substantially flat, unstructured metal body 20. However, a structured heat sink 20 is preferred, which, for example, is open and / or at least partially closed or completely closed on its cooling side. Preferably, microchannels are formed in the manufactured heat sink 20, through which a cooling fluid, preferably a coolant, can then be guided during operation. This allows the heat generated, for example, on the component side 4 or caused by a laser diode mounted on the connection surface 30, to be dissipated.To prevent the metal heat sink 20 from corroding over time, it is designed that the heat sink 20 has at least a partial corrosion protection layer 30. Otherwise, such corrosion would cause the heat sink 20 to either leak and / or clog the microchannels or cooling areas.

[0059] It has proven particularly advantageous to apply the corrosion protection layer 30 to cooling elements 20 that have been exposed to temperatures exceeding 600 °C, preferably exceeding 800 °C, and most preferably exceeding 1000 °C during their manufacturing process. Such temperature treatment results in granules with an average grain size in the range of 10 µm to 800 µm, preferably between 100 µm and 700 µm, and most preferably between 300 µm and 600 µm. This granulation provides a particularly advantageous contact and bonding surface on the outer surface to which the corrosion protection layer 30 is bonded, thereby increasing the adhesion of the corrosion protection layer 30. Such granulation is particularly common in cooling structures.Heat sinks 20, which are formed, for example, in the context of a soldering process or in the context of a direct bonding process or a diffusion bonding process, by connecting several metal layers, i.e., a first metal layer 21 and a second metal layer 21, together and / or by connecting the heat sink 20 to a ceramic element and / or a backside metallization of a metal-ceramic substrate 70 in the context of a DCB process or soldering process or a diffusion bonding process.

[0060] In Figure 9A corrosion protection layer 30 is schematically depicted on a cooling structure or heat sink 20. Preferably, such a corrosion protection layer has a thickness D of less than 3 µm, preferably less than 1000 nm, and particularly preferably less than 500 nm. In particular, it is provided that the corrosion protection layer 30 has a thickness D between 100 and 200 nm. Thicknesses of less than 3 µm can be produced by a sol-gel process, while coating with a corrosion protection layer of less than 500 nm is preferably carried out by gaseous deposition. The very thin corrosion protection layers 30 with thicknesses D of less than 500 nm prove to be particularly advantageous in the case of microchannel systems or microchannels, as this prevents the already small diameter of microchannels from being further reduced.Furthermore, the applied corrosion protection layer 30 prevents the formation of a thermal barrier that would otherwise have to be overcome by the heat transfer from the cooling element 20 to the coolant. It is particularly preferred that a SiO₂ layer is provided which covers the cooling structure 20 or at least partially its outer surface or the surface in contact with the coolant.

[0061] Preferably, the inner surfaces and / or fin elements or the rib-like elements 7 of the cooling structure 20 are provided with the corrosion protection layer 30, as are areas for connecting or sealing the cooler to the environment. It is particularly preferred that the inner surfaces of microchannel areas or microchannels are also provided with the corrosion protection layer 30. Reference symbol list:

[0062] 1 Support element 4 Electrical component 5 Component side 6 Cooling side 7 Web-like element 11 First metal layer 12 Second metal layer 13 Third metal layer 14 Lower cover layer 15 Upper cover layer 21 First part 22 Second part 24 Further recess 25 Fin structure 30 Connection surface 33 Transverse area 34 Leg area 40 Distribution structure 41 Inlet part 42 Discharge part 50 Feed structure 70 Metal-ceramic substrate 71 Ceramic element 72 Component metallization 75 Intermediate layer 73 Secondary layer A1 Spacing A2 Further spacing S Stack direction T1 First section T2 Second section Q Transverse direction Q1 First cross-sectional opening Q2 Second cross-sectional opening M Central axis D Thickness V Offset spacing RR Series direction HS1 First main flow direction HS2 Second Main flow direction HSE Main extent plane

Claims

1. Carrier element (1) for electrical components (4), wherein the carrier element (1) comprises a metallic heat sink (20) for dissipating heat emitted by the electrical component during its operation, wherein the heat sink (20) has a metal grain with an average grain size, wherein the average grain size is in a range between 10 µm and 800 µm, more preferably between 100 µm and 700 µm, and most preferably between 300 and 600 µm, characterized in that the heat sink (20) comprises, at least partially, an oxide-containing anti-corrosion layer (30).

2. Carrier element (1) according to claim 1, wherein the heat sink (20) is composed of at least a first metal layer (21) and a second metal layer (22).

3. Support element (1) according to one of the preceding claims, wherein the support element (1) comprises a metal-ceramic substrate (70).

4. Support element (1) according to claim 1, wherein the anti-corrosion layer comprises SiO2, TiO2, Al2O3, ZrO, CaO, K2O, and / or ZnO.

5. Support element (1) according to one of the preceding claims, wherein the anti-corrosion layer (30) has a thickness (D) of less than 3 µm, more preferably less than 1000 nm, and most preferably less than 500 nm.

6. Support element (1) according to one of the preceding claims, wherein the heat sink (20) is structured and / or comprises at least one microchannel.

7. Supporting element (1) according to one of the preceding claims, wherein a distance (A1) between opposite side walls in the at least one first metal layer (21). - is at least in some areas less than 0.4 mm, more preferably less than 0.3 mm, and most preferably less than 0.2 mm, or - has a value between 0.5 mm and 2.5 mm, more preferably between 0.7 mm and 1.5 mm, and most preferably between 0.8 mm and 1.2 mm.

8. Support element (1) according to one of the preceding claims, wherein the heat sink (20) is produced from copper and / or aluminum.

9. The method for manufacturing a carrier element (1) according to one of the preceding claims, wherein the heat sink (20) is exposed to a temperature above 600 °C for its formation and / or for bonding to a metal layer and / or to a ceramic element.

10. The method according to claim 9, wherein the heat sink (20) is exposed to a temperature between 100°C and 500°C, more preferably between 200° and 400°, and most preferably between 250° and 350°C, in order to form the anti-corrosion layer (30).

11. The method according to claim 9 or 10, wherein the anti-corrosion layer (30) is deposited on the heat sink (20) by means of physical vapor deposition.