METHOD FOR PRODUCING A METAL-CERAMIC SUBSTRATE

Description

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

[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] A prerequisite for providing 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 method, i.e., DCB or DAB methods, it is known from the prior art to bond the metal layer to the ceramic layer using a solder material. For example, EP 3 041 042 A1 discloses a phosphorus-containing solder foil with which such a bond can be achieved.

[0004] DE 10 2014 114 132 A1 discloses a method for bonding a metal layer to a ceramic element, in which an active solder layer is used for bonding. US 2017 271 137 A1 teaches bonding a metal layer to a ceramic element. The teaching of US 5,672,848 A deals with improving the wetting of an insulating layer. WO 93 / 23246 discloses a method for producing a metal-ceramic substrate in which at least one ceramic layer and at least one metal layer are arranged one above the other along a stacking direction.

[0005] Based on this prior art, the present invention seeks to provide an improved method for bonding the metal layer to the ceramic layer, which is particularly improved with regard to the thermomechanical stresses during production and with regard to its bonding spectrum with respect to the ceramic layers to be joined. This object is achieved by a method for producing a metal-ceramic substrate according to claim 1. Further advantages and properties emerge from the subclaims as well as the description and the accompanying figures.

[0006] According to a first aspect of the present invention, a method for producing a metal-ceramic substrate in which at least one ceramic layer and at least one metal layer are arranged one above the other along a stacking direction is provided, comprising: Providing the at least one ceramic layer, forming an interface metallization on the at least one ceramic layer, wherein the interface metallization comprises an active metal layer and a wetting metal layer, and bonding the at least one metal layer to the interface metallization, in particular by means of a direct metal bonding process, such as a DCB or DAB process, or an active soldering process, to form the metal-ceramic substrate, wherein the active metal layer and / or the wetting metal layer is exposed to an energy input to form the interface metallization, wherein light or inductive heating is used as the energy input.

[0007] Compared to the methods known from the prior art, the method according to the invention uses an interface metallization formed on the at least one ceramic layer, preferably on a top and / or bottom side of the at least one ceramic layer. Such an interface metallization proves particularly advantageous because it allows the bonding of a metal layer even in cases where, for example, bonding via a DCB or DAB method is not possible according to the prior art. This applies in particular to nitridic ceramics, especially silicon nitride and aluminum nitride.In the case of planned soldering, especially active soldering, interface metallization also allows for a more flexible choice of solder material, particularly insofar as solder materials with a melting temperature below 800°C, preferably below 700°C, and particularly preferably below 600°C, can also be used. This allows the completed soldering process to be carried out at a lower process temperature, which in turn has a positive effect on the thermomechanical stresses that would otherwise arise in the metal-ceramic substrate.

[0008] According to the invention, these are metal-ceramic substrates which, through appropriate structuring, are used as printed circuit boards (PCBs). For example, the method is used to form large cards, wherein several individual metal-ceramic substrates are subsequently formed from the large card in a singulation process. For example, structuring occurs after the at least one metal layer is bonded to the interface metallization, preferably by means of an etching and / or milling process. The structuring can provide corresponding conductor tracks and / or connections. It is preferred for those skilled in the art that, in addition to at least one metal layer on a top side of the at least one ceramic layer, at least one further metal layer serving as a backside metallization is provided on the opposite side.For example, the at least one further metal layer corresponds to the further metal layer, in particular with regard to shape and / or thickness and / or material.

[0009] In particular, the active metal layer and the wetting metal layer differ with regard to their choice of material. For example, the material for the active metal layer is Ti, Zr, Hf, Cr, Nb, and / or V, and the material for the wetting metal layer is Cu, Ag, Ni, In, and / or similar metals. It is also conceivable to use a copper oxide as the wetting metal layer, particularly if the 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 wetting metal layer directly adjoins the active metal layer in the stacking direction.Furthermore, it is conceivable that the wetting metal layer and / or active metal layer on the upper side differs from the wetting metal layer and / or active metal layer on the underside of the at least one ceramic layer or at least one further ceramic layer.

[0010] Furthermore, the metal-ceramic substrate comprises at least one metal layer that is materially bonded to an upper side of at least one ceramic layer, wherein the at least one metal layer and the at least one ceramic layer extend along a main extension plane and are arranged one above the other along a stacking direction running perpendicular to the main extension plane. Materials conceivable for the at least one 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, for example, is a sealing with a precious metal, in particular silver and / or gold, or ENIG (". electroless nickel immersion gold ") or edge encapsulation on the first or second metallization layer to suppress crack formation or widening is conceivable.

[0011] The at least one ceramic layer preferably 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 that at least one ceramic layer is 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. A ceramic which is as thermally conductive as possible is preferably used for the lowest possible thermal resistance.

[0012] Furthermore, it is conceivable that, in addition to the at least one ceramic layer, at least one further ceramic layer is provided, wherein a metallic intermediate layer is arranged between the at least one ceramic layer and the at least one further ceramic layer. 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. For example, the at least one metal layer is bonded to the at least one ceramic layer, and a metal layer provided as backside metallization is bonded to the at least one further ceramic layer.

[0013] In this case, the at least one metal layer is preferably bonded to the at least one ceramic layer by means of an AMB process and / or a DCB process.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] Furthermore, it is provided that the method comprises an at least partially primary arrangement of the active metal layer on the at least one ceramic layer and an at least partially secondary arrangement of the wetting metal layer on the active metal layer, wherein the active metal layer is preferably subjected to a further energy input between the primary arrangement and the secondary arrangement. As a result, the active metal layer is already melted before the secondary arrangement of the wetting metal layer. Alternatively, it is conceivable, for example, to dispense with this further energy input and to carry out the energy input for forming the interface metallization after the primary and secondary arrangement have been completed. This makes it possible to dispense with the further energy input, thereby accelerating the method.

[0018] When using a further energy input, a comparatively smaller further energy input after the primary arrangement (and before the secondary arrangement) can already be used to melt the active metal layer, whereby the energy expenditure in connecting the active metal layer to the at least one ceramic layer can be reduced, since the later energy input after the primary and secondary arrangement does not have to penetrate through the wetting metal layer. In particular, the use of the further energy input, i.e. after the primary arrangement, proves to be advantageous if a comparatively thick wetting metal layer is provided, i.e. in the case of wetting metal layers with a second thickness which is greater than 300 nm. A reduced further energy input orReduced energy input also proves to be advantageous because the metal-ceramic substrate is exposed to lower stresses, particularly thermal stresses, during the manufacturing process.

[0019] 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 PVD sputtering and / or reactive sputtering. This allows comparatively thin active metal layers and / or 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 active metal layer to the at least one ceramic layer. Furthermore, it is preferably provided that, for example, during a deposition process, structuring for the interface metallization or at least for the active metal layer and / or the wetting metal layer is carried out by means of appropriate masking.Such structuring in the interface metallization, which preferably corresponds to the planned structuring in the at least one metal layer, advantageously prevents bonding of the at least one metal layer to the at least one ceramic layer in the area of the planned structuring, thereby simplifying the etching step intended 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 for the active metal layer and / or wetting metal layer to be realized galvanically or electrochemically.

[0020] According to a further embodiment of the present invention, it is provided that a solder material is arranged between the at least one metal layer and the interface metallization, wherein the active metal layer and / or the wetting metal layer is exposed to the energy input after the solder material has been arranged between the at least one metal layer and the interface metallization or the wetting metal layer. This makes it possible to produce a metal-ceramic substrate comparatively quickly, since in particular all the individual layers are initially stacked on top of one another and the joining process is only triggered simultaneously by a final energy input. In this case, it has proven particularly advantageous to use a solder foil as the solder material, which is arranged between the wetting metal layer and the at least one metal layer. In this case, the active metal layer and / or the wetting metal layer can be part of the solder foil, i.e.i.e., as a common solder foil. Furthermore, it is preferably provided that the solder material has a layer thickness of between 1 µm and 100 µm, preferably between 1.5 and 50 µm, and particularly preferably between 2 µm and 20 µm. In particular, it is provided that the energy input melts not only the active metal layer and the wetting metal layer, but also the solder material, preferably the solder foil. Preferably, the energy input is dimensioned such that the solder material also melts. In particular, the energy input takes place immediately after the active metal layer, the wetting metal layer, the solder material, and the at least one metal layer have been stacked on the at least one ceramic layer along the stacking direction.

[0021] For example, the solder material can be a silver-based or a 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, especially 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 a solder material.

[0022] According to the invention, light is used as the energy input and preferably as the further energy input. For example, the light can be laser light that is guided over the active metal layer and / or wetting metal layer in one or more passes, so as to melt the active metal layer and / or wetting metal layer at least temporarily, in particular at specific points in time. For example, the laser is a pulsed laser, such as a CO2 laser and / or an ultrashort pulse laser, which generates pulses with a pulse duration of a few picoseconds or nanoseconds.

[0023] Preferably, a light flash is used, with the energy input of the light flash onto the active metal layer and / or the wetting metal layer preferably being at least 5 kW, preferably at least 8 kW, and particularly preferably between 10 kW and 15 kW. In particular, the energy input occurs as part 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. Thus, the active metal layer and / or the wetting metal layer are exposed to a brief thermal shock across the entire surface, for example, in the form of a brief (theoretical) heating to 800 °C. Preferably, light flashes are 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 enables the formation of the described interface metallization during a preparation step prior to the actual bonding of the at least one metal layer and / or at least one additional metal layer. For example, the energy input from a corresponding light flash induces the reaction Si 3 N 4 + Ti → TiN + Ti 3 Si 5 in the active metal.

[0024] In the prior art, however, 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. According to the invention, it is provided 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.

[0025] Furthermore, it is preferably provided that the active metal layer has a first thickness and the wetting metal layer has a second thickness, wherein the first thickness and / or the second thickness assumes a value between 0 nm and 5,000 nm, preferably between 50 nm and 2,500 nm, and particularly preferably between 100 nm and 1,000 nm. In particular, it is provided that the first thickness and / or second thickness, in particular the sum of the first and second thicknesses, is less than a third thickness of the at least one metal layer. Preferably, a ratio of the sum of the first thickness and the second thickness assumes a value below 0.1, preferably less than 0.05, and particularly preferably less than 0.02. This provides comparatively thin active metal layers and wetting metal layers, which allow the desired interface metallizations to be formed.

[0026] In particular, it is provided that the first thickness substantially corresponds to the second thickness. Alternatively, it is conceivable that a ratio of a first thickness to the second thickness assumes a value between 0.1 and 0.6, preferably between 0.15 and 0.4 and particularly preferably between 0.25 and 0.35, or that a ratio of the second thickness to the first thickness assumes a value between 0.1 and 2.0; preferably between 0.2 and 1.5; particularly preferably between 0.3 and 1.0. Furthermore, it is particularly preferably provided that the active metal layer, i.e. the first thickness, is at least 100 nm thick. A correspondingly large first thickness ensures that sufficient active metal is provided at the interface between ceramic and metal in order to realize a successful material-to-material connection between the at least one metal layer and the at least one ceramic layer.Particularly in the case of simultaneous melting of the active metal layer, the wetting metal layer, and the solder material, it has proven advantageous to use flashlight annealing, tempering, inductive heating, and / or pulsed laser light as energy input. It is advantageous to use different types of energy input that act on the active metal layer, the wetting metal layer, and / or the solder material simultaneously or at different times.

[0027] It is preferably provided that a process gas is used to form the interface metallization, i.e. during the energy input and / or the further energy input, i.e. the active metal layer and / or the wetting metal layer are exposed to a process gas during the energy input and / or the further energy input. Examples of a suitable process gas are argon, oxygen and / or nitrogen. The use of a process gas, in particular nitrogen or oxygen, can cause the metal layer, in particular the active metal layer and the wetting metal layer, to form additional oxides or nitrides which are stable when stored in the atmosphere. The use of inductive heat input is particularly preferred if the energy input occurs after the solder material and / or the further metal layer or the at least one metal layer is arranged on the wetting metal layer.

[0028] Furthermore, it is conceivable that the at least one metal layer and / or at least further metal layer is formed continuously, ie in the form of a sheet or in a foil.

[0029] Another subject matter is a method for producing a carrier substrate, comprising Providing at least one insulation layer; forming an interface metallization on the at least one insulation layer, wherein the interface metallization comprises an active metal layer and a wetting metal layer, and bonding the at least one metal layer to the interface metallization, in particular by means of a direct metal bonding method, such as a DCB or DAB method, or an active soldering method, to form the carrier substrate, wherein the active metal layer and / or the wetting metal layer is exposed to an energy input to form the interface metallization. For example, the carrier substrate is made of glass and / or It is made of plastic, especially a high-temperature-resistant plastic. Stacking the active metal layer, wetting metal layer, and solder material to form the carrier substrate has proven particularly advantageous.

[0030] 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.

[0031] 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, Fig.3: schematically shows a method for producing a metal-ceramic substrate according to a third preferred embodiment of the present invention and Fig.4: schematically shows a method for producing a metal-ceramic substrate according to a fourth preferred embodiment of the present invention.

[0032] 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 carrier for electronic or electrical components that can be connected to the metal-ceramic substrate 1, i.e., as a printed circuit board (PCB). Essential components of such a metal-ceramic substrate 1 are at least one ceramic layer 10 extending along a main extension plane HSE and at least one metal layer 20 connected to the at least one ceramic layer 10. The at least one ceramic layer 10 is made of at least one material comprising a ceramic.The at least one metal layer 20 and the at least one ceramic layer 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 bonded to one another via a bonding surface. According to the invention, the at least one 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 metal layer 20. However, a permanent bond, in particular a bonded connection, must be formed beforehand between the at least one metal layer 20 and the at least one ceramic layer 10.

[0033] In order to permanently bond the at least one metal layer 20 to the at least one ceramic layer 10, a system for producing the metal-ceramic substrate 1, for example using a DCB or DAB bonding process or an active soldering process (AMB process), comprises a furnace in which a stacked arrangement of the at least one ceramic layer 10 and the at least one metal layer 20 is heated, thus achieving the bond. For example, the at least one metal layer 20 is at least one metal layer 20 made of copper, wherein the at least one metal layer 20 and the at least one ceramic layer 10 are bonded to one another using a DCB (Direct Copper Bonding) bonding process. Alternatively, the at least one metal layer can be bonded to the at least one ceramic layer using an active soldering process or a thick-film process.

[0034] In the Figure 1In the illustrated embodiment of the metal-ceramic substrate 1, in addition to the at least one metal layer 20, at least one further metal layer 20' is provided on an opposite side of the at least one ceramic layer 10. In particular, the at least one further metal layer 20' serves as the backside metallization of the metal-ceramic substrate 1.

[0035] In particular, it is provided that the at least one metal layer 20 and the at least one further metal layer 20' are each connected to a top side and / or bottom side of the at least one ceramic layer 10 via an interface metallization 15. The use of an interface metallization 15 has the advantage that, for example, in the context of a soldering process, solder materials can also be used whose soldering temperature is lower than that provided for solder materials that can typically bond a metal layer 20 directly to a ceramic layer 10. This makes it possible to reduce the thermal stresses during the bonding process. In other words: the interface metallization 15 serves as an adapter for bonding the at least one metal layer 20 and / or the at least one further metal layer 20', in particular without having to take the special properties of the at least one ceramic layer 10 into account.This proves to be particularly advantageous when the at least one metal layer 20 and / or the at least one further metal layer 20' is to be connected to at least one ceramic layer 10, which is typically unsuitable for the application of a DCB or DAB process or method. For example, such an interface metallization 15 can be bonded to a nitridic ceramic, in particular a silicon nitride ceramic layer, whereby the bonding of the at least one metal layer 20 or the at least one further metal layer 20' via a direct metal bonding method, for example a DCB or DAB method, is in turn possible via the bonded interface metallization 15. The interface metallizations 15 each comprise an active metal layer 31 and a wetting metal layer 32, in particular on a top side and / or bottom side of the at least one ceramic layer 10.In particular, the active metal layer 31 directly adjoins a top side and / or bottom side of the at least one ceramic layer 10, while the wetting metal layer 32 is arranged on the active metal layer 31 arranged on the at least one ceramic layer 10 or directly adjoins the active metal layer 31. For example, the interface metallization 15 is formed from a two-layer system with the active metal layer 31 and the wetting metal layer 32. It is conceivable that the active metal layer 31 and the wetting metal layer 32 in the interface metallization 15 on the top side differ from those active metal layer 31 and wetting metal layer 32 provided for the interface metallization 15 on the bottom side of the at least one ceramic layer 15.

[0036] Furthermore, it is provided that the interface metallizations 15 extend at least over 40%, preferably 60% and particularly preferably more than 80% of a surface on the top side and / or back side of the at least one ceramic layer 10.

[0037] Furthermore, it is preferably provided that the active metal layer 31 is assigned a first thickness D1, a wetting metal layer 32 is assigned a second thickness D2, and the at least one metal layer 20 or the at least one further metal layer 20' is assigned a third thickness D3. The first thickness D1 and / or the second thickness D1 assumes a value between 0 nm and 5000 nm, preferably between 50 nm and 2500 nm, and particularly preferably between 100 nm and 1000 nm. Furthermore, it is particularly preferably provided that a ratio of the sum of the first thickness D1 and the second thickness D2 to the third thickness D3 assumes a value that is less than 0.1, preferably less than 0.05, and particularly preferably less than 0.02. In other words, the interface metallization layer 15 is comparatively thin compared to the third thickness D3 of the at least one metal layer 20.This also makes it possible to realize, for example, third thicknesses D3 that are greater than 1 mm, preferably greater than 1.5 mm, and particularly preferably between 1.5 mm and 3 mm. Such large third thicknesses D3 advantageously support heat dissipation directly at the electrical component, which is, for example, connected to the at least one metal layer 20.

[0038] In Figure 2 A method for producing a metal-ceramic substrate 1 according to an exemplary embodiment of the present invention is shown. In particular, the Figure 2the preparation of the at least one ceramic layer 10, which leads to the formation of the interface metallization 15. In particular, it is provided that after the at least one ceramic layer 10 has been provided on a top side and / or back side or bottom side of the at least one ceramic layer 10, preferably by a deposition process, such as by physical vapor deposition, a primary arrangement of the active metal layer 31 is carried out on the at least one ceramic layer 10. In particular, the active metal layer 31 covers the at least one ceramic layer 10 by more than 40%, preferably more than 60%, and particularly preferably more than 80%. Furthermore, the method provides that a wetting metal layer 32 is applied, at least in sections, to the active metal layer 31 applied during the primary arrangement.The wetting metal layer 32 can cover the active metal layer 31 over its entire surface and / or only up to 90%, preferably up to 80%, and particularly preferably up to 75%. For example, the wetting metal layer 32 on the upper side of the at least one ceramic layer 10 can differ from that on the underside of the at least one ceramic layer 10, in particular with regard to the material. The wetting metal layer 32 preferably covers at least 40%, preferably at least 60%, and particularly preferably more than 80% of the active metal layer 31 that was applied to the at least one ceramic layer 10 during the primary arrangement or primary arranging. To form a material-to-material connection with which the interface metallization 15 is bonded to the at least one ceramic layer 10, it is provided that an energy input 40 acts on the active metal layer 31 and / or the wetting metal layer 32.

[0039] In other words: The active metal layer 31 and the wetting metal layer 32 are exposed to an energy input 40, so that the wetting metal layer 32 and / or the active metal layer 31 melt due to the energy input 40, whereby during the melting the active metal of the active metal layer 31 reacts with the ceramic of the at least one ceramic layer 10 to form a material bond. By forming two metal layers, i.e. the active metal layer 31 and the wetting metal layer 32 from different metal materials, the melting temperature is below the melting temperature of the respective starting metals, so that the thermal load during the energy input for forming the interface metallization 15 is reduced, in particular also supported by the comparatively small first thickness D1 or second thickness D2. In the Figure 2In the illustrated embodiment, in addition to the energy input 40 after the active metal layer 31 and the wetting metal layer 32 are arranged one above the other, a further energy input 40' is additionally carried out, which is directed exclusively or solely at the active metal layer 31. For this purpose, after the primary arrangement of the active metal layer 31 and before the secondary arrangement of the wetting metal layer 32, a further energy input 40' is carried out, which leads to a pre-bonding of the active metal layer 31 to the at least one ceramic layer 10.

[0040] According to the invention, the energy input 40 and / or the further energy input 40' is an energy input by means of light. In addition to the use of laser light, it is particularly preferred that a light flash be used. In particular, the formation of the interface metallization 15 takes place using a so-called "flashlight annealing" process, in which a light flash illuminates the active metal layer 31 and / or wetting metal layer 32 arranged on the at least one ceramic layer 10 over a large area, i.e., a period of between 1 ms and 50 ms, across a large area, i.e., over more than 50%, particularly preferably more than 80% of the surface of the applied active metal layer 31 and / or wetting metal layer 32. The power of the light used preferably corresponds to a value of at least 5 kW, preferably at least 8 kW, and particularly preferably a value between 10 kW and 15 kW.The individual light pulses can have energy densities between 0.01 J / cm and 100 J / cm. It is conceivable that the further energy input 40' occurs through tempering, particularly in a vacuum. Furthermore, it is particularly preferred if the active metal layer 31 and / or wetting metal layer 32 is exposed to the energy input 40 and / or the further energy input 40' if this occurs under a process atmosphere or with the addition of a process gas. Examples of process gases are argon, oxygen, and / or nitrogen.

[0041] The primary arrangement and / or the secondary arrangement is carried out, for example, by means of sputtering, for example PVD sputtering and / or reactive sputtering.

[0042] In Figure 3 A method for producing a metal-ceramic substrate 1 according to a second exemplary embodiment of the present invention is shown. The embodiment from the Figure 3differs from those from Figure 1 in that in the embodiment the Figure 3 will dispense with a further energy input 40'. Accordingly, a primary and secondary arrangement is first carried out here and only after completion of the primary and secondary arrangement of the active metal layer 31 and the wetting metal layer 32 is the assembly of the at least one ceramic layer 10, the active metal layer 31 and the wetting metal layer 32 exposed to the energy input 40. In the Figures 2 and 3The energy inputs 40 are shown directed toward the top side of the assembly comprising at least one ceramic layer 10, wetting metal layer 32, and active metal layer 31. It will be understood by those skilled in the art that, in particular for bonding the additional metallization 20' and forming the interface metallization 15 provided for this purpose on the underside of the at least one ceramic layer 10, the energy input 40 can be applied both at the top side and at the bottom side of the assembly. It is conceivable that the same energy input or different energy inputs are applied at the top side and the bottom side.

[0043] Furthermore, it is conceivable that the primary arrangement and / or secondary arrangement takes place such that the active metal layer 31 and / or the wetting metal layer 32 has a structure on the top side or the bottom side of the at least one ceramic layer 10. Preferably, the structure embedded in the active metal layer 31 and / or the wetting metal layer 32 corresponds to that provided in the manufactured metal-ceramic substrate 1 for the at least one metal layer 20 and / or the at least one further metal layer 20'. In this case, the person skilled in the art understands a structure in particular to mean a recess that preferably extends to the top side and / or bottom side of the at least one ceramic layer 10.For example, one measure for such structuring is performed before the deposition process of primary arrangement and / or secondary arrangement by applying a masking that corresponds in particular to the intended structuring. This prevents active metal and / or wetting metal from being arranged in the areas of the planned structuring. Such structuring of the active metal layer 31 and / or the wetting metal layer 32, in particular of the interface metallization 15, proves particularly advantageous because it eliminates the need to etch away the cohesive bond in the boundary region between the at least one ceramic layer 10 and the at least one metallization layer 20 in the final etching process, the so-called "second etching," which typically proves to be particularly challenging in the manufacturing process.

[0044] In Figure 4A method for producing a metal-ceramic substrate 1 according to a third preferred embodiment of the present invention is shown. In the Figure 4 In the illustrated embodiment, the energy input 40 is only performed when the metal layer 20 and / or the further metal layer are already part of an assembly that has been assembled in advance or in preparation. For this purpose, after the primary arrangement of the active metal layer 31 and the secondary arrangement of the wetting metal layer 32, a soldering material 35, preferably as a soldering foil, is arranged on the wetting metal layer 32. The at least one metal layer 20 and / or the at least one further metal layer 20' are then arranged on the soldering material 35.

[0045] This assembly, which comprises at least one ceramic layer 10, the active metal layer 31, the wetting metal layer 32, the soldering material 35 and the at least one metal layer 20 or the at least one further metal layer 20', is finally subjected to an energy input 40 such that the interface metallization 15 is formed simultaneously on the top side and / or bottom side of the at least one ceramic layer 10 and the soldering material 35 melts at the same time in order to achieve the bonding of the at least one metallization layer 20 and / or the at least one further metal layer 20' as simultaneously as possible.The at least one further metal layer 20' allows for a comparatively fast manufacturing process for producing metal-ceramic substrates 1, in which, in particular, solder materials 35 can be used that have a comparatively low soldering temperature. This keeps the thermal load on the metal-ceramic substrate 1 to be produced as low as possible, which in turn allows thermomechanical loads or stresses to be kept as low as possible, which would otherwise lead to stresses in the manufactured metal-ceramic substrate, which could ultimately impair the service life of the manufactured metal-ceramic substrate 1. Furthermore, the energy consumption is reduced compared to a soldering process that requires a higher temperature. Preferably, the energy input occurs via a light flash, a laser pulse, an inductive effect, and / or heating. List of reference symbols:

[0046] 1Metal-ceramic substrate 10Ceramic layer 15Interface metallization 20Metal layer 20'further metal layer 31Active metal layer 32Wetting metal layer 35Solder material 40Energy input 40'further energy input HSEMain extension plane SStacking direction D1First thickness D2Second thickness D3Third thickness

Claims

1. Method for producing a metal-ceramic substrate (1), in which at least one ceramic layer (10) and at least one metal layer (20) are arranged on top of one another along a stacking direction (S) and the at least one metal layer (20) is structured to form conductor paths or connection points for electrical components, comprising - providing the at least one ceramic layer (10); - forming an interface metallization (15) on the at least one ceramic layer (10), wherein the interface metallization (15) comprises an active metal layer (31) and a wetting metal layer (32), and - bonding the at least one metal layer (20) to the interface metallization (15), in particular by means of a direct metal bonding method, such as a DCB or DAB method, or an active soldering process, in order to form the metal-ceramic substrate (1), wherein the active metal layer (31) and / or the wetting metal layer (32) is subjected to an energy input (40) in order to form the interface metallization (15) characterized in that light or inductive heating is used as the energy input (40).

2. Method according to claim 1, further comprising - at least partially primary arrangement of the active metal layer (31) on the at least one ceramic layer (10) and in particular - at least partially secondary arrangement of the wetting metal layer (32) on the active metal layer (31), wherein preferably between the primary arrangement and the secondary arrangement the active metal layer (31) is subjected to a further energy input (40').

3. Method according to claim 2, wherein the primary arrangement and / or the secondary arrangement is carried out by means of a deposition method, in particular a physical vapor deposition method.

4. Method according to one of the preceding claims, wherein a solder material (35) is arranged between the at least one metal layer (20) and the interface metallization (15), wherein the active metal layer (31) and / or the wetting metal layer (32) is exposed to the energy input (40) temporally after the solder material (35) is arranged between the at least one metal layer (20) and the interface metallization (15).

5. Method according to one of the preceding claims, wherein light is used as a further energy input (40').

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

7. Method according to one of the preceding claims, wherein sintering is used as a further energy input (40').

8. Method according to one of the preceding claims, wherein the active metal layer (31) has a first thickness (D1) and the 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 and 5000 nm, more preferably between 50 and 2500 nm and most preferably between 100 nm and 1000 nm.

9. Method for the production of a metal-ceramic substrate according to one of the preceding claims, comprising - forming an interface metallization (15) on the at least one insulating layer, wherein the interface metallization (15) comprises an active metal layer (31) and a wetting metal layer (32), - wherein the active metal layer (31) and / or the wetting metal layer (32) is subjected to an energy input (40) in order to form the interface metallization (15).