METHOD FOR PRODUCING A METAL-CERAMIC SUBSTRATE AND METAL-CERAMIC SUBSTRATE PRODUCED BY SUCH A METHOD

Description

[0001] The present invention relates to a method for producing a metal-ceramic substrate and a metal-ceramic substrate produced by such a method.

[0002] Metal-ceramic substrates are well known in the art, for example, as printed circuit boards or circuit boards, for example from DE 10 2013 104 739 A1, DE 19 927 046 B4, and DE 10 2009 033 029 A1. Typically, connection pads for electrical components and conductor tracks are arranged on one component side of the metal-ceramic substrate, wherein the electrical components and the conductor tracks can be interconnected to form electrical circuits. Key components of metal-ceramic substrates are an insulating layer, preferably made of a ceramic, and at least one metal layer bonded to the insulating layer. Due to their comparatively high insulation strengths, insulating layers made of ceramic have proven particularly advantageous in power electronics. By structuring the metal layer, conductor tracks and / or connection pads for the electrical components can then be realized.

[0003] US 2017 044072 A1 and JP 2019 085 327 A disclose processes for producing metal-ceramics. In these processes, both a wetting layer and an active metal layer are used to bond a copper layer. However, when the copper layer is combined with an aluminum layer, only the wetting layer is used.

[0004] A prerequisite for creating such a metal-ceramic substrate is a permanent bond between the metal layer and the ceramic layer. In addition to a so-called direct bonding process, i.e., DCB or DAB processes, it is known from the prior art to bond the metal layer to the ceramic layer using a solder material.

[0005] Typically, metal-ceramic substrates are provided with identical front-side and back-side metallizations, for example, each made of copper. Bonding dissimilar metals is generally impossible due to the process temperatures. Sequential joining is difficult due to the different expansion coefficients of metal and ceramic.

[0006] Based on this prior art, the present invention has for its object to provide an improved method for bonding the metal layer to the ceramic layer, in particular for bonding a first metal layer and a second metal layer to the ceramic layer, wherein the first metal layer and the second metal layer differ from one another with regard to their material composition.

[0007] This object is achieved by a method for producing a metal-ceramic substrate according to claim 1 and a metal-ceramic substrate produced by such a method according to claim 10. Further advantages and properties emerge from the subclaims as well as the description and the attached figures.

[0008] According to a first aspect of the present invention, a method for producing a metal-ceramic substrate is provided, in which at least one first metal layer, one ceramic element and at least one second metal layer are arranged one above the other along a stacking direction, wherein the ceramic element is arranged between the at least one first metal layer and the at least one second metal layer in the stacking direction and wherein the at least one first metal layer is different from the at least one second metal layer, comprising: Providing the ceramic element; forming a first interface metallization on a first side of the ceramic element, wherein the first interface metallization comprises a first active metal layer and a first wetting metal layer, forming a second interface metallization on a second side of the ceramic element opposite the first side of the ceramic element, wherein the second interface metallization comprises a second active metal layer and a second wetting metal layer, bonding the at least one first metal layer to the first interface metallization, in particular by means of an active soldering process, to form the metal-ceramic substrate, and bonding the at least one second metal layer to the second interface metallization, in particular by means of an active soldering process, wherein the first interface metallization, in particular the first active metal layer and / or the first wetting metal layer, and / or the second interface metallization, in particular the second active metal layer and / or the second wetting metal layer, is exposed to an energy input, in particular before the at least one first metal layer is bonded to the first interface metallization and the at least one second metal layer is bonded to the second interface metallization.

[0009] Compared to the methods provided in the prior art, the invention provides for a first interface metallization to be provided on a first side of the ceramic element and a second interface metallization to be provided on a second side of the ceramic element opposite the first side. The first interface metallization and / or the second interface metallization serves to provide a type of adapter or joining layer for connecting the at least one first metal layer or the at least one second metal layer to the ceramic element. This advantageously makes it possible to carry out the soldering process, by means of which the at least one first metal layer is bonded to the first interface metallization orThe at least one second metal layer is bonded to the second interface metallization, so that, for example, solder materials can be used that result in a cohesive bond at a comparable or identical soldering temperature, particularly on both sides simultaneously. In particular, it is conceivable to use solder materials that cause a comparatively low thermal load on the metal-ceramic substrate to be produced, thus avoiding corresponding thermomechanically induced stresses in the metal-ceramic substrate during the manufacturing process, which could otherwise reduce the service life of the manufactured metal-ceramic substrate.

[0010] In addition, by means of the first interface metallization and the second interface metallization, it is possible to have more freedom in the choice of material for the at least one first metal layer and the at least one second metal layer, so that, for example, aluminum can be used as the back-side metallization, i.e. as at least one second metal layer, while a copper layer can be used as at least one first metal layer or front-side metallization. This makes it possible to reduce the costs and / or weight of the metal-ceramic substrate to be manufactured. Preferably, the ceramic element comprises at least one ceramic layer. Preferably, the ceramic element has at least two ceramic layers, between which a metallic intermediate layer is provided which, for the purpose of heat spreading, has a thickness greater than 1.4 mm, or which are different in order to provide a hybrid ceramic.

[0011] The metal-ceramic substrate is preferably a printed circuit board (PCB). For example, the method is used to form large cards, wherein a plurality of individual metal-ceramic substrates are subsequently formed from the large card in a singulation process. In particular, it is provided that after the at least one first metal layer has been bonded to the first interface metallization or after the at least one second metal layer has been bonded to the second interface metallization - for example by etching, in particular a multi-stage etching, and / or milling - a structuring is carried out in the at least one first metal layer and / or at least one second metal layer. This makes it possible, for example, to produce conductor tracks and / or connections in the at least one first metal layer.It is also conceivable that a structuring, for example in the form of fins, is realized in the at least one second metal layer, which are part of a cooling structure or form the cooling structure, along which a cooling fluid is guided during operation of the metal-ceramic substrate in order to dissipate corresponding heat that is generated during operation of components on the at least one first metal layer.

[0012] In particular, the first or second active metal layer and the first or second wetting metal layer differ in terms of their choice of material. For example, the material for the first or second active metal layer is Ti, Zr, Hf, Cr, Nb and / or V and preferably the material for the first or second wetting metal layer is Cu, Ag, Ni, In and / or similar metals. It is also conceivable that a copper oxide is used as the first or second wetting metal layer, in particular if the first or second active metal layer was bonded to the at least one ceramic layer in a process gas atmosphere using an energy input and / or further energy input. Furthermore, it is provided that the first or second wetting metal layer is directly adjacent to the first or second active metal layer, viewed in the stacking direction. Furthermore, it is conceivable that the first or second wetting metal layer and / or first orsecond active metal layer on the top side differs from the first or second wetting metal layer and / or first or second active metal layer on the bottom side of the ceramic element.

[0013] Furthermore, the metal-ceramic substrate comprises at least one first metal layer, which is materially bonded to an upper side of the ceramic element, and at least one second metal layer, which is materially bonded to an underside of the ceramic element, wherein the at least one first metal layer, the at least one second metal layer, and the ceramic element extend along a main extension plane and are arranged one above the other in a stacking direction running perpendicular to the main extension plane. Possible materials for the at least one first metal layer or the at least second metal layer are copper, aluminum, molybdenum, and / or their alloys, as well as laminates such as CuW, CuMo, CuAl, AlCu, and / or CuCu, in particular a copper sandwich structure with a first copper layer and a second copper layer, wherein a grain size in the first copper layer differs from that of a second copper layer.Furthermore, it is preferably provided that the at least one metal layer is surface-modified. A surface modification can be, for example, a seal with a precious metal, in particular silver and / or gold, or ENIG ("". electroless nickel immersion gold ") or edge casting on the at least one first or second metal layer to suppress crack formation or widening is conceivable.

[0014] Preferably, one ceramic element comprises Al 2 O 3 , Si 3 N 4 , AIN, an HPSX ceramic (i.e. a ceramic with an Al 2 O 3 matrix which comprises an x percent proportion of ZrO 2 , for example Al 2 O 3 with 9% ZrO 2 = HPS9 or Al 2 O 3 with 25% ZrO 2 = HPS25), SiC, BeO, MgO, high-density MgO (> 90% of the theoretical density), TSZ (tetragonally stabilized zirconium oxide) or ZTA as the material for the ceramic. It is also conceivable for the ceramic element to be designed as a composite or hybrid ceramic in which, in order to combine various desired properties, several ceramic layers which each differ in terms of their material composition are arranged one above the other and joined together to form an insulation layer. Preferably, a ceramic which is as thermally conductive as possible is used for the lowest possible thermal resistance.

[0015] Furthermore, it is conceivable that in addition to the at least one ceramic layer, at least one further ceramic layer is provided in the ceramic element, wherein a metallic intermediate layer is arranged between the at least one ceramic layer and the at least one further ceramic layer, wherein the metallic intermediate layer is preferably thicker than 1.4 mm and / or thicker than the at least one ceramic layer and the at least one further ceramic layer.

[0016] The metal layer is preferably bonded to the ceramic layer by means of an AMB process and / or a DCB process.

[0017] A person skilled in the art understands a "DCB process" (Direct Copper Bond Technology) or a "DAB process" (Direct Aluminum Bond Technology) to be a process used, for example, to bond metal layers or sheets (e.g., copper sheets or foils, or aluminum sheets or foils) to one another and / or to ceramic or ceramic layers, using metal or copper sheets or metal or copper foils that have a layer or coating (melting layer) on their surface. In this process, described, for example, in US Pat. No. 3,744,120 A or DE23 19 854 C2, this layer or coating (melting layer) forms a eutectic with a melting temperature below the melting temperature of the metal (e.g., copper), so that by applying the foil to the ceramic and heating all the layers, they can be bonded to one another by melting the metal or the ceramic.Copper essentially only in the area of the reflow layer or oxide layer.

[0018] In particular, the DCB process then comprises the following process steps: Oxidizing a copper foil to form a uniform copper oxide layer; applying the copper foil to the ceramic layer; heating the composite to a process temperature between approximately 1025 and 1083°C, e.g., approximately 1071°C; cooling to room temperature.

[0019] An active solder process, for example, for joining metal layers or metal foils, in particular copper layers or copper foils to ceramic material, is a process that is also specifically used for producing metal-ceramic substrates. A bond is created between a metal foil, for example copper foil, and a ceramic substrate, for example aluminum nitride ceramic, at a temperature between approximately 650 and 1000°C using a brazing alloy that, in addition to a main component such as copper, silver, and / or gold, also contains an active metal. This active metal, which is, for example, at least one element from the group consisting of Hf, Ti, Zr, Nb, and Ce, creates a bond between the solder and the ceramic through a chemical reaction, while the bond between the solder and the metal is a metallic brazing joint. Alternatively, a thick-film bonding process is also conceivable.

[0020] In particular, the solder material is preferably a silver-based or copper-based solder material. In a silver-based solder material, silver is the main component, i.e., the component with the highest proportion by weight, whereas in a copper-based solder material, copper is the main component. Examples of a silver-based solder material are AgCu, in particular AgCu28, AgCuln, AgCuSn, and AgCuGa. Examples of a copper-based base material are copper CuSn, Culn, CuGa, CuInSn, CuInMb, and CuGaSn. It is also conceivable to use NiCrMn, Sn, SnSb, or SnCu as the base material.

[0021] According to a preferred embodiment, the bonding of the at least one first metal layer and the bonding of the at least one second metal layer is carried out simultaneously or at least partially simultaneously. This advantageously allows the at least one first metal layer or the at least one second metal layer to be bonded to the ceramic element simultaneously. Accordingly, the metal-ceramic substrate to be manufactured is not subjected to unnecessarily long temperature treatments required to bond the at least one first metal layer and the at least one second metal layer to the ceramic element. Furthermore, time and energy can be advantageously saved during the manufacture of the metal-ceramic substrate, and the manufacturing process is thus accelerated.

[0022] Furthermore, it is preferably provided that the ceramic element comprises at least one ceramic layer and / or at least one composite comprising a ceramic layer. For example, it is conceivable for the ceramic element to comprise at least two ceramic layers, between which a metallic intermediate layer is arranged, wherein the metallic intermediate layer is greater than 1.4 mm and / or thicker than a layer thickness of the respective ceramic layers of the composite. This allows an intermediate metallic layer to be formed between the two ceramic layers, which can already contribute to heat spreading, thus supporting or improving heat dissipation.

[0023] Furthermore, it is preferably provided that the bonding of the at least one first metal layer and the at least one second metal layer is carried out below a soldering temperature of 800 °C, preferably below 700 °C and particularly preferably below 650 °C. Soldering temperatures between 230 °C and 650 °C are preferably provided. In particular, in comparison to the temperatures used in a commonly used direct metal joining process, for example a DCB or DAB process, or in a soldering process in which the at least one first metal layer and / or the at least one second metal layer is bonded directly to the at least one ceramic element, soldering temperatures can be used during the production of the metal-ceramic substrate that are lower than those of the commonly used solder materials or process temperatures.This is particularly advantageous because expansion of the individual layers during production leads to thermomechanical or mechanical stresses in the finished metal-ceramic substrate, which are detrimental to the lifetime of the finished metal-ceramic substrate. Furthermore, the energy consumption during production can be reduced.

[0024] It is expediently provided that the at least one first metal layer and / or the at least one second metal layer has a hybrid structure and / or a surface modification. This advantageously allows the bonding properties of the at least one first or second metal layer to be further improved. For example, the at least one first metal layer comprises a second sub-section which is thinner than a first sub-section of the at least one first metal layer and in particular has a lower melting temperature. The bond to the first side of the first interface metallization then takes place via the second sub-section. For example, the first sub-section is made of a metal alloy of a metal from which the second sub-section of the first metal layer is formed.It is also conceivable that the first subsection and the second subsection, for example, the at least one second metal layer, are plated, or that the first and second subsections are surface-modified to form a hybrid structure. For example, a layer of AlSi facing the second side is conceivable for the at least one second metal layer, which simplifies the bonding of the at least one second metal layer to the ceramic element.

[0025] Preferably, it is provided that an at least partially primary arrangement of the first active metal layer and / or the second active metal layer and / or an at least partially secondary arrangement of the first wetting metal layer on the active metal layer and / or the second wetting metal layer on the second active metal layer is carried out by means of a deposition process, wherein between the primary arrangement and the secondary arrangement, the first active metal layer and / or the second active metal layer is subjected to a further energy input. In particular, it has proven advantageous to realize the first interface metallization and / or second interface metallization by means of an energy input and / or a further energy input. In particular, use is made of the fact that a comparatively thin design of the first active metal layer, the second active metal layer, the By applying a targeted energy input to the first wetting metal layer and / or the second wetting metal layer, it is possible to melt the metals, creating a cohesive bond to the first and / or second side of the ceramic element. By successively applying an energy input or a further energy input, the power component used by the first energy input and the further energy input can be kept as low as possible, thereby minimizing the respective load on the metal-ceramic substrate to be produced.

[0026] Preferably, light is used as the energy input or additional energy input. For example, laser light is used, which is specifically directed at the first active metal layer, the second active metal layer, the first wetting metal layer, or the second wetting metal layer. Preferably, a light flash is used, wherein the energy input of the light flash onto the active metal layer and / or the wetting metal layer is preferably at least 5 kW, more preferably at least 8 kW, and particularly preferably between 10 kW and 15 kW. In particular, the energy input takes place within the framework of a so-called "flashlight annealing," in which a light flash illuminates the active metal layer and / or the wetting metal layer across the entire surface for 0.6 ms to 20 ms.For example, the active metal layer and / or the wetting metal layer are exposed across their entire surface to a brief thermal shock, for example in the form of brief heating at 800 °C. Light flashes are preferably used whose energy density is between 0.01 J / cm 2 and 100 J / cm 2 , preferably between 0.5 J / cm 2 and 15 J / cm 2 and / or whose pulse duration is between 0.2 ms and 20 ms. It has been found that treatment with such light flashes makes it possible to form the described interface metallization during a preparation step before the actual bonding of the at least one metal layer and / or of at least one further metal layer. For example, the energy input from a corresponding light flash causes the active metal to undergo the reaction Si 3 N 4 + Ti . → TiN + Ti 3 Si 5 .

[0027] Alternatively and / or additionally, it is provided that the energy input and / or further energy input comprises sintering or tempering, i.e. preferably the active metal layer and / or the wetting metal layer is / are heated or warmed, in particular under inert conditions. It is conceivable that the heating is carried out in a vacuum or in a protective gas atmosphere. It is also conceivable that the energy input is initiated via an inductive effect. Furthermore, it is conceivable that the active metal layer and / or the wetting metal layer are pressurized, i.e. pressed together, during the energy input or the further energy input.

[0028] It is preferably provided that the primary arrangement and / or the secondary arrangement is realized by means of a deposition process, in particular by means of a physical vapor deposition process. For example, this is DC sputtering and / or reactive sputtering. This allows comparatively thin first or second active metal layers and / or first or second wetting metal layers to be realized in a targeted manner, which in turn has a positive effect on the energy input required to bond at least the first or second active metal layer to the ceramic element. Furthermore, it is preferably provided that, for example, during a deposition process, structuring for the first or second interface metallization or at least for the first or second active metal layer and / or the first or second wetting metal layer is carried out by means of appropriate masking.Such structuring in the first interface metallization, which preferably corresponds to the planned structuring in the at least one first metal layer, advantageously prevents bonding of the at least one first metal layer to the ceramic element in the region of the planned structuring, thereby simplifying the etching step provided for the final structuring, the so-called "second etching," i.e., the etching step that creates the isolation trenches between individual metal sections of the at least one metal layer. Furthermore, it is conceivable that the first or second active metal layer and / or the first or second wetting metal layer are realized galvanically or electrochemically or by a currentless wet-chemical process, preferably with Cr as the active metal.

[0029] In a further preferred embodiment, it is provided that the first active metal layer has a first thickness and the first wetting metal layer has a second thickness, wherein the first thickness and / or the second thickness assumes a value between 0 nm or 10 nm and 5000 nm, preferably between 50 nm and 2500 nm, and particularly preferably between 100 nm and 1000 nm. In particular, it is particularly preferably provided that the first thickness substantially corresponds to the second thickness. However, it is also conceivable that the second thickness is up to five times greater than the first thickness. In this case, "substantially equal" is to be understood in particular as meaning that the values are equal or correspond to one another within a tolerance of 50%, preferably 30% or particularly preferably 10%.By appropriately dimensioning the first active metal layer and / or the first wetting metal layer, it is advantageously possible to provide a layer system that can be melted relatively easily with a corresponding energy input, thus creating the cohesive bond for connecting the first interface metallization to the ceramic element. In particular, the above ratios for the first and second thicknesses also apply analogously to the second active metal layer and the second wetting metal layer.

[0030] Furthermore, it is particularly preferred that the first wetting metal layer and the second wetting metal layer differ from one another, in particular with regard to the metal material. This makes it possible to further influence the solder material to be used during the bonding process between the at least one first metal layer at the first interface metallization and the bonding of the at least one second metal layer at the second interface metallization.

[0031] Preferably, a process gas is used to form the first interface metallization and / or the second interface metallization, in particular during the introduction of the energy input and / or the further energy input. For example, the process gas is argon, nitrogen, and / or oxygen. The use of such process gases advantageously makes it possible to form corresponding oxides and / or nitrides in the first active metal layer, the second active metal layer, the first wetting metal layer, and / or the second wetting metal layer. These prove particularly advantageous for intermediate storage, as they form a type of protective layer.

[0032] The present invention further relates to a metal-ceramic substrate produced using the method according to the invention. All advantages and features described for the method can be applied analogously to the metal-ceramic substrate.

[0033] Further advantages and features will become apparent from the following description of preferred embodiments of the subject matter according to the invention with reference to the accompanying figures. Individual features of the individual embodiments can be combined with one another within the scope of the invention.

[0034] It shows: Fig.1: schematically shows a metal-ceramic substrate according to a first preferred embodiment of the present invention, Fig.2: schematically shows a method for producing a metal-ceramic substrate according to a second preferred embodiment of the present invention and Fig.3:schematically shows a method for producing a metal-ceramic substrate according to a third preferred embodiment of the present invention.

[0035] In Figure 11 schematically shows a metal-ceramic substrate 1 according to a first preferred embodiment of the present invention. Such a metal-ceramic substrate 1 preferably serves as a holding element for electronic or electrical components that can be connected to the metal-ceramic substrate 1, i.e. as a printed circuit board or PCB. Essential components of such a metal-ceramic substrate 1 are a ceramic element 10 extending along a main extension plane HSE and at least one first metal layer 20 connected to the ceramic element 10 and at least one second metal layer 22 opposite the at least one first metal layer 20. The ceramic element 10 is made from at least one material comprising a ceramic.For example, the ceramic element 10 is a ceramic layer, in particular a single ceramic layer, or a composite structure into which, for example, a ceramic layer is integrated. The at least one first metal layer 20, the at least one second metal layer 22 and the ceramic element 10 are arranged one above the other along a stacking direction S running perpendicular to the main extension plane HSE and, in a manufactured state, are at least partially materially connected to one another via a connection surface. Preferably, the at least one first metal layer 20 is then structured to form conductor tracks or connection points for the electrical components. For example, this structuring is etched into the at least one first metal layer 20.However, a permanent bond, in particular a material bond, must be formed beforehand between the at least one first metal layer 20 and the at least one ceramic layer 10. The at least one second metal layer 22 is preferably provided as a cooling element. For example, this is a solid metal block or a cooling structure equipped with cooling fins or a cooling channel system that extends within the at least one second metal layer 22.

[0036] In order to permanently bond the at least one first metal layer 20 or the at least one second metal layer 22 to the at least one ceramic element 10, a system for producing the metal-ceramic substrate 1, for example in a DCB or DAB bonding process or active soldering process (AMB process), comprises a furnace in which a stacked arrangement of the ceramic element 10 and the at least one metal layer 20 is heated and the bonding is thus achieved.

[0037] In particular, the Figure 1The illustrated embodiment of the metal-ceramic substrate 1 is a metal-ceramic substrate 1 whose at least one first metal layer 20 differs from the at least one second metal layer 22, in particular with regard to a metal material used. For example, the at least one first metal layer 20 is a copper layer and the at least one second metal layer 22 is an aluminum layer. It is provided that the at least one first metal layer 20 is connected to a first side S1 of the at least one ceramic element 10 via a first interface metallization 15, while the at least one second metal layer 22 is connected via a second interface metallization 16 on a second side S2 of the at least one ceramic element 10 opposite the first side S1 of the at least one ceramic element 10.In other words: It is preferably provided that the at least one first metal layer 20 and / or the at least one second metal layer 22 is not immediately and directly connected to the at least one ceramic element 10, but via a first interface metallization 15 or second interface metallization 16 acting as an adapter. By using a first interface metallization 15 and / or second interface metallization 16, it is advantageously possible to use solder materials 35 whose working range is preferably below 650 °C. In particular, it is conceivable that the use of a first interface metallization 15 and / or a second interface metallization 16 makes it possible to use the same solder material 35 for connecting the at least one first metal layer 20 and the at least one second metal layer 22.

[0038] In Figure 2A method for producing a metal-ceramic substrate 1 according to a first present invention is shown. In particular, the method shown in Figure 2The representation shown is an illustration of preparation steps for forming a first interface metallization 15 and / or a second interface metallization 16. Furthermore, it is preferably provided that the first interface metallization 15 has a first active metal layer 31 and a first wetting metal layer 32, while the second interface metallization 16 comprises a second active metal layer 41 and a second wetting metal layer 42. In this case, it is preferably provided that the active metal layers, iethe first active metal layer 31 and the second active metal layer 41 have a first thickness D1, the first wetting metal layer 32 and the second wetting metal layer 42 have a second thickness D2, and the at least first metal layer and the at least second metal layer each have a third thickness D3, wherein a ratio of a sum of the first thickness D1 and second thickness D2 to a third thickness D3 is less than a value of 0.5, preferably less than 0.1, and particularly preferably less than 0.05. In other words, a comparatively thin first interface metallization 15 and / or second interface metallization 16 is provided.

[0039] In particular, it is provided that after the ceramic element 10 has been provided, a first active metal layer 31 is arranged on a top side or on a first side S1 of the ceramic element 10 by a primary arrangement and a second active metal layer 41 is arranged on a second side S2 of the ceramic element 10 opposite the first side S1. Preferably, during the primary arrangement, the first or second active metal layer 31, 41 is applied to the first side S1 or the second side S2 by a deposition method, for example sputtering. Subsequently, it is provided that a first wetting metal layer 32 is arranged on the first active metal layer 31 and a second wetting metal layer 42 is applied to the second active metal layer 41, preferably by a deposition method, such as sputtering.

[0040] For the material-to-material bonding of the two-layer system comprising the first active metal layer 31 and the first wetting metal layer 32 or the second active metal layer 41 and the second wetting metal layer 42, it is preferably provided that the layer system comprising the first active metal layer 31 and the first wetting metal layer 32 or the second active metal layer 41 and the second wetting metal layer 42 is exposed to an energy input 40. For example, the energy input 40 is effected by means of light, for example laser light or pulsed laser light or in the form of a light flash, which is designed to melt the first or second active metal layer 31, 41 and the first or second wetting metal layer 32, 42 and thereby cause a material-to-material bond through reaction between the first side S1 and / or the second side S2 of the ceramic element 10 and the first or second active metal layer 31, 41.In particular, the first and / or second interface metallization 15, 16 is formed accordingly using flashlight annealing. This involves a light flash with a pulse duration between 0.2 and 20 ms, which leads to an energy input of up to 20 J / cm 2 or 100 J / cm 2 . In particular, it is provided that the first interface metallization 15 and / or the second interface metallization 16 extend over more than 50%, preferably more than 70%, and particularly preferably more than 80% of the area of the first side S1 or the second side S2, respectively.

[0041] In Figure 3 A method for producing a metal-ceramic substrate 1 according to a second exemplary embodiment of the present invention is shown. In particular, it is provided that the Figure 3 The illustrated process steps follow the preparation steps described in Figure 2are shown. In particular, it is provided that a solder material 35, preferably in the form of a solder foil and / or a solder paste, is applied to the formed first interface metallization 15 and / or second interface metallization 16 and is arranged in particular between the first interface metallization 15 and the at least one first metallization 20 or between the second interface metallization 16 and the at least one second metal layer 22. It is conceivable that the solder materials 35 correspond to one another and / or differ from one another. Furthermore, it is preferably provided that the at least one first metal layer 20 and / or at least second metal layer 22 is a hybrid structure.For example, the at least one first metal layer 20 comprises a first subsection 26 and a second subsection 27, wherein, for example, the first subsection 26 comprises a first metal and the second subsection 27 comprises a metal alloy based on the metal of the first subsection 26. Preferably, the second subsection 27 is thinner than the first subsection 26 by a factor of 5. Preferably, the formation of the second subsection 27 serves to provide a metal alloy that is meltable, in particular below a temperature of 650°C, in order to cause the at least one first metal layer 20 to melt during the soldering process, which ultimately contributes to the material-to-material connection between the at least one first metal layer 20 and the first interface metallization 15 via the solder material 35.It is particularly preferred, for example, that the first subsection 26 is made of copper and / or the second subsection 27 is a low-melting copper alloy.

[0042] Furthermore, it is provided that the at least one second metal layer 22 comprises a first subsection 29 and a second subsection 28, wherein the first subsection 29 and the second subsection 28 of the at least one second metal layer 22 were preferably produced during plating, for example, roll-bonding. For example, the first subsection 29 is an aluminum body or base body, on the side of which facing the second side S2 of the ceramic element 10, the second subsection 28 is arranged. This second subsection 28 is made of AlSi, for example. In particular, it is provided that the first subsection 29 of the at least one second metal layer 22 is at least a factor of 5 thicker than the second subsection 28 of the at least one second metal layer 22.Following the assembly of the at least one first metal layer 20, the at least one second metal layer 22, the solder materials 35 and the ceramic element 10 provided with the first interface metallization 15 and the second interface metallization 16, the elements of the assembly arranged one above the other along a stacking direction S are joined to one another in a common soldering process, preferably at a temperature below 650 °C.

[0043] Following the material-to-material bonding of the at least one first metal layer 20 on the first side S1 of the ceramic element 10 and the at least one second metal layer 22 on the second side S2 of the ceramic element 10, it is provided to structure the at least one first metal layer 20 and / or the at least one second metal layer 22, preferably in a multi-stage etching step. For this purpose, masking is carried out, and the preferably multi-stage etching step is carried out based on the masking. This makes it possible, for example, to introduce isolation trenches into the at least one first metal layer 20 and / or other types of structuring into the at least one second metal layer 22. Furthermore, it is preferably provided that following the structuring, a laser treatment is carried out, preferably for the purpose of singulating the individual metal-ceramic substrates, before a surface treatment finally takes place. List of reference symbols:

[0044] 1 Metal-ceramic substrate 10 Ceramic element 15 First interface metallization 16 Second interface metallization 20 First metal layer 26 First section of the first metal layer 27 Second section of the first metal layer 28 Second section of the second metal layer 29 First section of the second metal layer 22 Second metal layer 31 Active metal layer 32 Wetting metal layer 35 Solder material 40 Energy input HSE Main extension plane SS Stacking direction D1 First thickness D2 Second thickness D3 Third thickness S1 First side S2 Second side

Claims

1. Method for producing a metal-ceramic substrate (1), in which at least one first metal layer (20), a ceramic element (10) and at least one second metal layer (22) are arranged on top of one another along a stacking direction (S), wherein the ceramic element (20) is arranged in the stacking direction (S) between the at least one first metal layer (20) and the at least one second metal layer (22) and wherein the at least one first metal layer (20) differs from the at least one second metal layer (22) with respect to their metal materials, comprising: - providing the ceramic element (10); - forming a first interface metallization (15) on a first side (S1) of the ceramic element (10), wherein the first interface metallization (15) comprises a first active metal layer (31) and a first wetting metal layer (32), - forming a second interface metallization (16) on a second side (S2) of the ceramic element (10) opposite to the first side (S1) of the ceramic element (10), wherein the second interface metallization (16) comprises a second active metal layer (41) and a second wetting metal layer (42), - bonding of the at least one first metal layer (20) to the first interface metallization (15), in particular by means of an active soldering method, in order to form the metal-ceramic substrate (1), and - bonding of the at least one second metal layer (22) to the second interface metallization (16), in particular by means of an active soldering method, wherein the first interface metallization (15) and / or the second interface metallization (16) is exposed to an energy input (40), in particular temporally before the bonding of the at least one first metal layer (20) to the first interface metallization (15) and / or the at least one second metal layer (22) to the second interface metallization (16).

2. Method according to claim 1, wherein the bonding of the at least one first metal layer (20) and the bonding of the at least one second metal layer (22) are performed simultaneously.

3. Method according to one of the preceding claims, wherein the bonding of the at least one first metal layer (20) and the at least one second metal layer (22) is performed below a soldering temperature of 800°C, preferably below 700°C and particularly preferably below 650°C.

4. Method according to one of the preceding claims, wherein the at least one first metal layer (20) and / or the at least one second metal layer (22) has a hybrid structure and / or a surface modification.

5. Method according to one of the preceding claims, wherein - at least partially primary arranging of the first active metal layer (31) and / or the second active metal layer (41) and / or - at least partially secondary arranging of the first wetting metal layer (32) on the active metal layer (31) and / or the second wetting metal layer (42) on the second active metal layer (42) is performed by means of a deposition method wherein, between the primary arranging and the secondary arranging, the first active metal layer (31) and / or the second active metal layer (41) is exposed to a further energy input.

6. Method according to one of the preceding claims, wherein light is used as energy input (40) and / or further energy input.

7. Method according to claim 6, wherein a flash of light is used, wherein the energy input (40) of the flash of light onto the first active metal layer (31), the second active metal layer (41), the first wetting metal layer (32) and / or the second wetting metal layer (42) is preferably at least 5 kW, more preferably at least 8 kW and particularly preferably between 10 and 15 kW.

8. Method according to one of the preceding claims, wherein the first active metal layer (31) has a first thickness (D1) and the first wetting metal layer (32) has a second thickness (D2), wherein the first thickness (D1) and / or the second thickness (D2) has a value between 0 nm and 5000 nm, more preferably between 50 nm and 2500 nm and particularly preferably between 100 nm and 1000 nm.

9. Method according to one of the preceding claims, wherein a process gas is used in order to form the first interface metallization (15) and / or the second interface metallization (16).

10. Metal-ceramic substrate (1) manufactured by a method according to one of the preceding claims.