Methods for the production of metal-ceramic substrates

Abstract

Method for producing a metal-ceramic substrate (1), comprising - Providing a ceramic element (30), a first metal element (11) and a second metal element (12), wherein the ceramic element (30) extends substantially along a principal extension plane (HSE), - Bonding the first metal element (11) to the ceramic element (30), particularly at a temperature above 500 °C, wherein the first metal element (11) and the ceramic element (30) are arranged one above the other in a stacking direction (S) that is perpendicular to the principal extension plane (HSE), and - Connecting the second metal element (12) to the first metal element (11) to form a metallization (10, 20), in particular a component metallization (10) and / or a backside metallization (20), wherein after arranging the second metal element (12) on the first metal element (11) the first metal element (11) and the second metal element (12) interact in a form-locking manner in a direction parallel to the principal extension plane (HSE), characterized in that the first metal element (11) is structured to form first metal element sections (11') after the first metal element (11) is connected to the ceramic element (30).

Description

[0001] The present invention relates to a method for producing a metal-ceramic substrate. Substrates for electrical components, for example in the form of metal-ceramic substrates, are well known in the prior art 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 side of the metal-ceramic substrate, and the electrical components and conductor tracks can be interconnected to form electrical circuits. Essential components of the metal-ceramic substrates are an insulating layer, preferably made of a ceramic, and a metallization or component metallization bonded to the insulating layer. Due to their comparatively high insulating strength, ceramic insulating layers have proven particularly advantageous in power electronics.By structuring the metallization, conductive tracks and / or connection surfaces for the electrical components can then be created.

[0002] For such substrates, especially metal-ceramic substrates, the different material choices for the insulating layer on the one hand and the metallization on the other fundamentally create the problem that, due to different coefficients of thermal expansion, thermomechanical stresses can be induced or caused by heat generation, which occurs particularly during the manufacturing of the metal-ceramic substrate. These stresses can lead to bending or even damage to the metal-ceramic substrate.

[0003] The state of the art counteracts this by providing, in addition to the component metallization on the opposite side of the component metallization on the ceramic element, a backside metallization of comparable thickness. This creates a symmetry that counteracts the otherwise one-sided bending force and instead compensates for the bending forces that occur. However, this limits the freedom in choosing the dimensions of the component metallization and the backside metallization. For example, the thicknesses of the component metallization and the backside metallization must not differ significantly.

[0004] German patent DE 10 2017 131 077 A1 describes a method for creating a contact surface for mounting a semiconductor chip on a substrate. German patent DE 10 2017 203 194 A1 describes a power module with at least two parts that can be electrically and / or thermally connected by plugging and / or clamping. US patent US 2007 0 128 845 A1 relates to a connection structure of an integrated circuit. The teaching of EP 3 474 643 A1 relates to a multi-concave flank profile of a metallization.

[0005] Starting from this premise, the present invention aims to provide a metal-ceramic substrate that allows for increased flexibility and freedom in the dimensioning and design of the metallization, whether it be the component metallization or the backside metallization.

[0006] The present invention solves the problem with the method according to claim 1. Further advantageous embodiments can be found in the dependent claims, the description and the figures.

[0007] According to a first aspect of the present invention, a method for producing a metal-ceramic substrate is provided, comprising, - Providing a ceramic element, a first metal element and a second metal element, wherein the ceramic element and preferably the first metal element and / or the second metal element extend substantially along a principal extension plane, - Bonding the first metal element to the ceramic element, particularly at a temperature above 500 °C, wherein the first metal element and the ceramic element are arranged one above the other in a stacking direction perpendicular to the main extension plane, and - Connecting the second metal element to the first metal element to form a metallization, in particular a component metallization and / or a backside metallization, wherein, after arranging the second metal element on the first metal element, the first metal element and the second metal element interact in a form-fitting manner in a direction parallel to the main extension plane.

[0008] In contrast to the prior art, the invention provides that a second metal element is attached to a first metal element, wherein, when the second metal element is positioned on the first metal element, particularly before, after, and / or during the attachment, a positive fit is formed that acts in a direction parallel to the principal plane of extension. This advantageously makes it possible to use the positive fit as a positioning aid to align the second metal element relative to the first metal element. Furthermore, the positive fit can contribute to securing the second metal element to the first metal element.Furthermore, by attaching the second metal element to the first metal element, it is advantageously possible to increase design freedom in creating the metallization, be it the component metallization or the backside metallization, through appropriate individualization of the second metal element, without causing the metal-ceramic substrate to deflect during the manufacturing process.

[0009] This applies particularly when the bonding of the first metal element to the ceramic element takes place at a temperature above 500 °C, preferably above 700 °C, and most preferably above 1000 °C. In particular, a first thickness of the first metal element corresponds to a third thickness, which is assigned to a backside metallization. This backside metallization is bonded to the side of the ceramic element opposite the first metal element during the bonding process. This creates a symmetry during the bonding process, which can then be broken by the subsequent bonding of the second metal element to the first metal element.In other words, the process makes it possible to achieve an asymmetrical distribution of metal material on the component side and back without fear of bending or a bimetallic effect when bonding the metal to the ceramic, since the required symmetry on the component side and back of the ceramic element can be ensured for the first metal element.

[0010] Furthermore, it is possible to increase the flexibility in the design freedom of the component metallization or the backside metallization, since, for example, it is no longer necessary to provide a symmetrical layer thickness distribution on the front and back of the ceramic element or the metal-ceramic substrate. It is also conceivable that the second metal element has a width that is greater and / or smaller than the width of the first metal element. In the case of a greater width of the first metal element compared to the second, a stepped gradient in the final metallization layer, in particular the final component metallization or the final metallization section, can be achieved.In the case of a width of the second metal element that is greater than the width of the first metal element, a projecting second metal element section can be realized that extends beyond the outermost perimeter of the first metal element or the first metal element section in a direction that runs parallel to the principal extension plane.

[0011] Furthermore, the first and second metal elements in the manufactured metal-ceramic substrate can be distinguished because the thermal treatment of the first metal element during its bonding to the ceramic element results in a grain structure in the first metal element that differs from that in the second metal element. This is due to the different thermal treatments at different temperatures. Preferably, the second metal element is attached to the first metal element purely mechanically. For example, the second metal element is attached to the first metal element by a corresponding positive fit and / or a frictional connection. The positive fit and / or frictional connection preferably acts along a direction perpendicular to the main plane of extension.Furthermore, it is conceivable that the second metal element is attached to the already attached first metal element in a clip-like manner. For this purpose, the second metal element, for example, engages an undercut embedded in or on the edge of the first metal element to create an additional positive fit that acts parallel to the stacking direction.

[0012] Furthermore, it is conceivable that, in addition to or as an alternative to the positive locking, a material-bonded connection between the first and second metal elements is realized, for example by means of a soldering material or an adhesive, in order to connect the second metal element to the first metal element.

[0013] In particular, this is a metal-ceramic substrate used as a printed circuit board (PCB) in which a metallization, i.e., a component metallization, is formed on the component side. Due to its structuring, this metallization comprises several electrically isolated metallization sections. These metallization sections form, for example, connection pads or conductor tracks of the PCB. Preferably, the metallization is formed from the first and second metal elements. It is also conceivable that the metallization includes metallization sections formed from at least the first and second metal elements, and metallization sections formed from only the first metal element.

[0014] Preferably, the ceramic element comprises Al2O3, Si3N4, AIN, an HPSX ceramic (i.e., a ceramic with an Al2O3 matrix containing an x ​​percent ZrO2 content, 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 an insulating element in order to combine various desired properties.

[0015] Possible materials for the first and / or second metal element include copper, aluminum, molybdenum, tungsten, 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, CuMo, or AlSiC. Preferably, the first metal element is identical to the second metal element in terms of material or differs from it. Furthermore, it is preferably provided that the first or second metal element is surface-modified on the manufactured metal-ceramic substrate, particularly as a component metallization. Surface modification could include, for example, sealing with a precious metal, especially silver and / or gold, or (electroless) nickel or ENIG (electroless nickel immersion gold), or edge sealing of the metallization to suppress crack formation or propagation.For example, the metal used for the component metallization differs from the metal used for the reverse side metallization.

[0016] The bonding of the metal layer to the ceramic element can be achieved, for example, via a DCB process, an AMB process, diffusion bonding and / or hot isostatic pressing.

[0017] A "DCB process" (Direct Copper Bond Technology) or a "DAB process" (Direct Aluminum Bond Technology) is understood by those skilled in the art to be a process that serves, for example, to bond metal layers or sheets (e.g., copper sheets or foils or aluminum sheets or foils) to each other and / or to ceramics or ceramic layers, using metal or copper sheets or foils that have a layer or coating (fused-on layer) on their surface. In this process, described, for example, in US 3,744,120 A or DE 23 19 854 C2, this layer or coating (fused-on layer) forms a eutectic with a melting point below that of the metal (e.g., copper), so that by placing the foil on the ceramic and heating all layers, they can be bonded together by melting the metal or foil.Copper is essentially only present in the area of ​​the molten layer or oxide layer.

[0018] Preferably, the ceramic layer and the metal layer are joined by means of a direct metal bonding process, hot isostatic pressing, a soldering process and / or a diffusion bonding process.

[0019] In particular, the DCB method then includes, for example, the following process steps: • Oxidizing a copper foil in such a way that a uniform copper oxide layer is formed; • Applying the copper foil to the ceramic layer; • Heating the composite to a process temperature between approximately 1025 and 1083°C, e.g. to approximately 1071°C; • Cool to room temperature.

[0020] An active soldering process, e.g., for joining metal layers or foils, especially copper layers or foils, to ceramic material, is a process specifically used for producing metal-ceramic substrates. At a temperature between approximately 600 and 1000°C, a bond is created between a metal foil, for example, copper foil, and a ceramic substrate, for example, aluminum nitride ceramic, using a hard solder. This solder contains an active metal in addition to a main component such as copper, silver, and / or gold. This active metal, which is, for example, at least one element from the group Hf, Ti, Zr, Nb, Ce, forms a bond between the solder and the ceramic through a chemical reaction. The bond between the solder and the metal is a metallic brazing joint. Alternatively, a thick-film bonding process is also conceivable.

[0021] Hot isostatic pressing is known, for example, from EP 3 080 055 B1, the content of which is hereby explicitly referenced with regard to hot isostatic pressing.

[0022] Preferably, the second metal element and / or the first metal element has at least one projection or at least one recess in a direction parallel to the main extension plane to form the positive fit. The projections and / or recesses extend particularly in the stacking direction. Preferably, the recesses and projections are designed to be complementary to each other so that they can engage with one another and preferably interact with each other in a force-fit and / or form-fit manner to support the cohesion between the first and second metal elements.It is also conceivable that, for example, the recesses are larger than the raised areas in order to collect a joining agent, such as a solder (soft or hard solder) or an adhesive, within these recesses and to also accommodate the corresponding raised area. The adhesive can, for example, be electrically conductive and / or thermally conductive. The first and second metal elements can also be welded together or joined by cold working and / or pressing. The recess can also serve as a solder mask. It is particularly preferred that the raised area is formed at the outermost edge of the first and / or second metal element in order to encompass the outermost circumference of the second and / or first metal element when the second metal element is arranged on top of the first.It is also conceivable, for example to form a stepped profile, that there is a raised area only on one side of the edge area of ​​the second metal element or the first metal element, which serves as a stop when positioning the second metal element on the first metal element, in order to facilitate the alignment and positioning of the second metal element on the first metal element during manufacturing.

[0023] Preferably, the first and second metal elements are connected to each other via a plug-in mechanism when stacked on top of each other. In particular, several recesses and several protrusions, preferably more than five, engage with one another, thereby creating a positive-locking and / or friction-locking connection. Preferably, the recesses and protrusions are designed to interact in an interference fit. For example, a plurality, particularly more than five, of recesses and protrusions reduces the likelihood of a loose connection, since even considering manufacturing tolerances, a sufficient number of recesses and protrusions ensures a friction-locking connection between the first and second metal elements.

[0024] Preferably, the at least one recess and / or the at least one raised area is formed, for example, by punching and / or embossing on one side of the first and / or second metal element. A pre-etched part is also conceivable. The depth of the recess and / or raised area can be, for example, less than 1 / 3 of the first and / or second thickness, preferably less than 1 / 4, and particularly preferably less than 1 / 5 of the first and / or second thickness. Alternatively, the recesses and raised areas can be created by an etching process or by material removal using laser light.

[0025] According to the invention, the first metal element is structured after it is bonded to the ceramic element. In particular, the structuring of the first metal element takes place before the bonding of the second metal element to the first. This makes it possible, for example, to create metallization layers or sections whose total thickness is greater than the distance between two metallization sections. For example, the structuring of the first metal element can be achieved by etching.The isotropic effect of the etching agent creates a trench between the first metal element sections thus produced, with a trench width essentially equal to or greater than the thickness of the first metal element. By placing the second metal element on top of the first and preferably bonding it together, the overall thickness of the metallization layer can be increased without having to enlarge the required insulating trench between the adjacent metallization sections. This makes it possible, for example, to produce metal-ceramic substrates in which two adjacent metallization sections are still relatively close to each other even when the overall thickness of the metallization or the metallization sections is large, for example, greater than 1.5 mm.This makes it possible to provide power modules that have a compact arrangement of conductor tracks and connection surfaces.

[0026] Preferably, the first metal element has a first thickness dimensioned in the stacking direction, and the second metal element has a second thickness dimensioned in the stacking direction, the second thickness being greater than the first thickness, in particular more than twice, preferably more than four times, and most preferably more than 7.5 times. This advantageously makes it possible to produce particularly narrow isolation channels between metallization sections in the metallization layer of the manufactured metal-ceramic substrate. Alternatively, it is also conceivable that the first thickness of the first metal element essentially corresponds to the second thickness of the second metal element. This allows, for example, a stepped profile in the final metallization layer to be realized if, for instance, the width of the second metal element is smaller than that of the first metal element.In particular, it is possible to create a metallization layer with equal thickness levels if the first thickness corresponds to the second thickness.

[0027] Preferably, the second metal element comprises a side surface that is not parallel to the main plane of extension and that is not flat, i.e., curved, at least partially, preferably completely. In particular, the provision of a second metal element, which is placed on top of the first metal element, allows for a free design of the metallization, especially with regard to the side surfaces. This makes it possible, for example, to shape the side surfaces and optimize them for improved thermal shock resistance. For example, it is conceivable that the side surface has at least one, preferably several, concavely curved and / or convexly curved sections, and it is also conceivable that a flat side surface runs obliquely, for example at an angle of 45° to the main plane of extension.This allows, for example, the metallization section to be designed for optimal heat dissipation.

[0028] In particular, it is provided that the first thickness and / or the third thickness has a value between 0.1 and 1.2 mm, preferably between 0.3 and 1 mm, and most preferably between 0.3 and 0.6 mm. The second thickness preferably assumes a thickness between 0.3 and 8 mm, more preferably between 0.5 and 6 mm, and most preferably between 0.8 and 5 mm. The first thickness, the second thickness, and the third thickness are preferably understood as the maximum extent in a direction perpendicular to the principal plane of extension.

[0029] Preferably, the second metal element and a further second metal element are connected to different first metal element sections, wherein the second further metal element and the second metal element preferably have different second thicknesses. This advantageously makes it possible to implement a metallization with a height profile using simple means. This also makes it possible, for example, to individually address components that exhibit increased energy or heat dissipation or require rapid heat transfer.In these cases, an increased overall thickness of the metallization layer can be individually achieved in a section of the metal-ceramic substrate, while other areas, which are only intended as conductor tracks, have a lower overall thickness in the final component metallization, composed of the first metal element and the second metal element.

[0030] Preferably, the second metal element has a first section and a second section for connection to different first metal element sections, wherein the first section and the second section are connected to each other via a bridge section, the bridge section preferably being at least partially removed, particularly after the second metal element has been connected to the first metal element. For example, the bridge section is realized by a residual metal layer that connects the first metal section and the second metal element. The final removal of the material in the bridge section ensures the isolation of the adjacent metallization sections after the second metal element has been connected to the first metal element. This guarantees the appropriate isolation of the adjacent metallization sections.The bridge section can be selectively removed, or an upper partial layer of the second metal element can be removed over a larger area, for example by etching, until the insulation trenches are exposed.

[0031] Preferably, the metallization, in particular the component metallization comprising the first and second metal elements, has a total thickness greater than 1.5 mm, preferably greater than 2 mm, and most preferably greater than 3 mm, wherein the distance between two adjacent sections of the metallization is preferably less than 1.5 mm, more preferably less than 2.5 mm, and most preferably less than 3 mm. The described method thus makes it possible to provide metal-ceramic substrates with a comparatively narrow insulation trench, thereby enabling the most compact power module possible, in which conductor tracks and / or connection surfaces are distributed on the metal-ceramic substrate in the most space-efficient manner.

[0032] Another object is a metal-ceramic substrate produced using the method according to the invention. All the advantages and properties described for the method can be transferred analogously to the metal-ceramic substrate and vice versa. In the manufactured metal-ceramic substrate, the first metal element and the second metal element can be distinguished from one another due to different grain sizes in the metal.

[0033] Further advantages and features will become apparent from the following description of preferred embodiments of 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: a metal-ceramic substrate according to a first preferred embodiment of the present invention Fig. 2a to 2d a method for producing a metal-ceramic substrate according to a second preferred embodiment of the present invention Fig. 3a to 3d a method for producing a metal-ceramic substrate according to a third exemplary embodiment of the present invention, Fig. 4 a method for producing a metal-ceramic substrate according to a fourth exemplary embodiment of the present invention, Fig. 5 a method for producing a metal-ceramic substrate according to a fifth exemplary embodiment of the present invention and Fig. 6 a method for producing a metal-ceramic substrate according to a sixth exemplary embodiment of the present invention.

[0035] In Fig. Figure 1 schematically depicts a metal-ceramic substrate 1 according to a first preferred embodiment of the present invention. Such a metal-ceramic substrate 1 is preferably a carrier for electrical components (not shown). It is particularly provided that the metal-ceramic substrate 1 comprises a ceramic element 30 and at least one metallization 10, wherein the ceramic element 30 and the at least one metallization 10 extend along a principal extension plane HSE. The at least one metallization 10 is connected to the ceramic element 30, and the at least one metallization 10 and the ceramic element 30 are arranged one above the other in a stacking direction S perpendicular to the principal extension plane HSE. It is particularly provided that the at least one metallization 10 comprises a plurality of metal sections 10' (in Fig. 1 not shown), which are, for example, electrically isolated from each other and arranged side by side along a direction parallel to the main extension plane HSE.

[0036] Furthermore, it is particularly preferred that, viewed in the stacking direction S, a backside metallization 20 is provided on the ceramic element 30 on the side opposite the at least one metallization 10. The backside metallization 20 is particularly intended to counteract otherwise occurring bending caused by thermomechanical stresses, which in turn result from different coefficients of thermal expansion in the at least one metallization 10 and the ceramic element 30.

[0037] This occurs particularly during the bonding process, during which an arrangement consisting of a metal layer and a ceramic element 30 is exposed to a temperature of at least 500 °C, or approximately 1080 °C in the case of a DCB process. Therefore, in the prior art, the thickness of a metal layer bonded to the ceramic element 30 on one side of the component is selected to be approximately equal to the thickness of the backside metallization 20, in order to compensate for the bending forces on the opposite side through the corresponding symmetry between the component's front and back sides. This effectively counteracts any deflection of the metal-ceramic substrate 1.

[0038] However, this limits the dimensioning of the (component) metallization 10, since the component metallization 10 must be adapted to the backside metallization 20 and vice versa.

[0039] To increase the design freedom of the metallization, be it the component metallization 10 or the backside metallization 20, it is preferably provided that a ceramic element 30, a first metal element 11, and a second metal element 12 are provided. In particular, it is provided that the first metal element 11 is first bonded to the ceramic element 30. A bonding method is selected that takes place at a temperature above 500°C, preferably above 800°C, and most preferably above 1000°C. It is provided that a first thickness D1 of the first metal element 11 preferably corresponds substantially to a third thickness D3 of the backside metallization 20.This ensures the desired symmetry between the component side and the back side of the metal-ceramic substrate 1 during the bonding process, thereby counteracting deflection due to force compensation caused by the symmetry. After bonding the first metal element 11 to the ceramic element 30, the second metal element 12 is preferably bonded to the first metal element 11 to form the metallization 10, in particular the component metallization 10 and / or back side metallization 20. This advantageously allows the dimensions and / or shape of the component metallization 10 to be influenced or shaped by the second metal element 12. For example, by appropriately selecting the second thickness D2 of the second metal element 12, a total thickness D of the (component) metallization 10 can be achieved that is significantly greater than that of the back side metallization 20.

[0040] It is specifically provided that the first metal element 11 and the second metal element 12, after the second metal element 12 has been arranged on the first metal element 11, interact with each other in a form-fitting manner in a direction parallel to the principal extension plane HSE. This makes it possible to ensure, when arranging the second metal element 12, that the correct positioning of the second metal element 12 relative to the first metal element 11 is assumed. In the Fig. In the embodiment shown in Figure 1, the positive locking is achieved by projections formed on the edge of the second metal element 12, which project in a direction that is essentially parallel to the stacking direction S relative to the general orientation of the second metal element 12 (along the main extension plane HSE). In particular, it is provided that the projection encompasses at least the first metal element 11 and thereby ensures the positive locking in a direction parallel to the main extension plane HSE.

[0041] In the Fig. In the embodiment shown in Figure 1, two projections are formed on the edges of the second metal element 12, arranged on opposite sides. This allows the first metal element 11 to be fitted onto the second metal element 12, ensuring the alignment of the second metal element 12. Furthermore, the first metal element 11 and the second metal element 12 are positively locked together in two opposite directions. Preferably, the second metal element 12 and the first metal element 11 are dimensioned and / or designed such that, in addition to the positive locking in a direction parallel to the main extension plane HSE, a further frictional locking is achieved in a direction parallel and / or perpendicular to the stacking direction S. This is ensured, for example, by a corresponding press fit between the first metal element 11 and the second metal element 12.Furthermore, it is conceivable that a projection is formed only on one side of the second metal element 12, in particular at the edge of the second metal element 12, which serves for the positive locking with the first metal element 11, in particular the positive locking at the outermost circumference of the first metal element 11.

[0042] Furthermore, it is preferably provided that, before the second metal element 12 is attached to the first metal element 11 and after the first metal element 11 is attached to the ceramic element 30, the first metal element 11 is structured in order to create first metal element sections 11' that are electrically insulated from one another. This can be achieved, for example, by an etching process or by the application of laser light or mechanical processing of the attached first metal element 11.

[0043] In this Fig. In the embodiment not explicitly shown, it is then possible to create metallization sections 10 by attaching second metal elements 12 to the electrically insulated first metal element sections 11' of the first metal element 11. These metallization sections are arranged very close to each other, i.e., adjacent to each other, despite their total thickness D. This would not be possible, for example, by etching alone, since in that case the distance between two metallization sections 10' would be approximately equal to or greater than the thickness of the metallization 10. This advantageously makes it possible to create insulation grooves, even in metallizations with a large total thickness, particularly greater than 1.5 mm, which are comparatively narrow, and in particular narrower than the total thickness D of the metallization 10.

[0044] In particular, it is advantageously possible to provide metal-ceramic substrates 1 that are asymmetrical with respect to the first thickness D1 and the third thickness D3, i.e., whose component metallization thickness 10 is greater than the backside metallization thickness 20, or vice versa. This ensures that symmetry is maintained during the bonding process of the first metal element 11 to the ceramic element 30, thereby counteracting deflection during the manufacturing process.

[0045] Preferably, the connection of the second metal element 12 to the first metal element 11 is additionally effected by a material bond, for example by using a solder material or adhesive with which the second metal element 12 can be bonded to the first metal element 11.

[0046] In the Fig. Figures 2a-2d illustrate an exemplary method for producing a metal-ceramic substrate 1 according to a second exemplary embodiment of the present invention. After forming a pre-substrate in which the first metal element 11 is bonded to the ceramic element 30, and in particular a back-side metallization 20 is bonded to the side of the ceramic element 30 opposite the first metal element 11, the bonded first metal element 11 and the bonded back-side metal layer 20 are structured. In particular, it is provided that at least sectionally, material of the bonded first metal element and / or the back-side metal layer is removed such that the ceramic element 30 is exposed again. On the component side, such exposed areas form the course of the insulation trench 18 in the finished product, which electrically insulates or separates two adjacent metallization sections 10' from each other.Furthermore, it is conceivable that material is also removed from the back of the metal-ceramic substrate 1, extending to the ceramic element 30. This element is located opposite another area that is also free of material, so that, for example, a predetermined breaking point can be provided in this area to break out individual metal-ceramic substrates 1 from a metal-ceramic substrate 1 supplied as a large card. In other words, in this area, a separation of two adjacent metal-ceramic substrates 1, manufactured together in a large card, takes place in the subsequent manufacturing process.

[0047] Furthermore, it is conceivable that expansion recesses 28 are incorporated into the back layer in order to advantageously relieve corresponding stresses that could otherwise arise during operation or manufacturing of the metal-ceramic substrate 1 due to high temperatures.

[0048] Furthermore, it is provided that recesses or indentations 24 are incorporated on a side of the first metal element 11 facing away from the ceramic element 30. Such recesses 24 can be created, for example, by a punching or embossing process on the side of the first metal element 11 facing away from the ceramic element 30. It is conceivable that the recess 24 is created after the bonding process of the first metal element 11 to the ceramic element 30 or that it is incorporated into the first metal element 11 before the bonding process. In particular, it is provided that there are a plurality of recesses 24, which extend over more than 80% of the side facing away from the ceramic element 30.

[0049] Furthermore, it is preferably provided that the recesses 24 are assigned a depth T, wherein the ratio of the depth T to the first thickness D1 is between 0.01 and 0.25, preferably between 0.01 and 0.1, and particularly preferably between 0.01 and 0.05. It has thus been found that even small depths T for the recesses 24 are sufficient compared to the first thickness D1 in order to later use them for a positive fit with the second metal element 12. Furthermore, it is provided that in the Fig. In the process step shown in 2c, the second metal element 12 is connected to a first metal element 11. In particular, in the exemplary embodiment of Fig. 2c provides that several second metal elements 12, i.e. at least one second metal element 12 and another second metal element 12', are provided separately and are each arranged on different first metal element sections 11' that are electrically insulated from each other and joined to them.

[0050] In contrast to the embodiment above, the following is required to form the positive connection between the first metal element 11 and the second metal element 12. Fig. 1. No overlapping of the second metal element 12 is provided, but rather protrusions 25 on the side of the second metal element 12 facing the ceramic element 30. These protrusions 25 engage accordingly in the recesses 24 on the side of the first metal element 11 facing away from the ceramic element 30, in order to form the desired positive fit. In the Fig. In the embodiment shown in 2d, the second metal element 12 and the further second metal element 12' differ from each other with regard to size and / or shape.

[0051] For example, it is possible that a second metal element 12' has a greater second thickness D2 than the second thickness D2 of the second metal element 12. Furthermore, it is conceivable that the second metal element 12 has a width B that is greater or less than the width B of the first metal element 11 or the first metal element section 11' to which the second metal element 12 is or will be attached, causing the second metal element 12 to project or be recessed in a direction parallel to the principal extension plane HSE relative to the outermost circumference of the first metal element 11 or the first metal section 11'. This makes it possible to further reduce the distance between two metallic metallization sections 10' in the manufactured metal-ceramic substrate 1 if the second metal element 12 has a greater width B than the first metal element 11 or the first metal element section 11'.Alternatively and in . Fig. 2d not shown, it is also conceivable that the width B of the second metal element 12 is smaller than the width B of the first metal element 11 or of the corresponding first metal element section 11', thereby realizing a stepped gradient in the metallization layer 10 in the manufactured metal-ceramic substrate 1.

[0052] In the Fig. In the embodiment shown in Figure 2d, it is particularly provided that the second metal element 12 and the further second metal element 12' have different second thicknesses D2, resulting in a height profile for the component metallization 10. This can be used, for example, to provide higher overall thicknesses D for the metallization sections 10' in special applications where better heat dissipation is necessary. The greater overall thickness D allows the thermal conductivity of the metallization 10 to be utilized, which can ensure improved heat dissipation.

[0053] Furthermore, it is possible to distinguish the second metal elements 12 from the first metal elements 11 in the finished state, since different grain sizes result from the different thermal treatments during the manufacturing process (temperature treatment for the first metal element and no or different temperature treatment for the second metal element), which can also be assigned to the first metal element 11 and the second metal element 12 after the manufacturing process.

[0054] In the Fig. Figures 3a-3d illustrate a method for producing a metal-ceramic substrate 1 according to a third exemplary embodiment of the present invention. This method differs from the methods described in Figures 3a-3d. Fig. 3a - 3d of the one from the embodiment of the Fig. 2a - 2d such that in the embodiment of the Fig. 3a - 3d a common second metal element 12 is connected to various first metal element sections 11'. For this purpose, a second metal element 12 is provided, comprising a first section A1 and a second section A2, which are connected to each other via a bridge section BA, in particular a residual metal layer. While the first section A1 and / or the second section A2 have a second thickness D2 and, in particular, have protrusions 25 and / or recesses 24 on their side facing the ceramic element 30, the bridge section BA has a reduced second thickness D2 compared to the second thickness D2. By appropriately dimensioning the first section A1 and the second section A2, respectively, in accordance with the size and position of the first metal element sections 11', it is advantageously possible to connect the first section A1 and the second section A2 to first metal element sections 11'.This is preferably achieved via a plug-in mechanism. The second metal element 12 can be fastened to the first metal element 11 by means of a frictional connection acting in the stacking direction S.

[0055] After the second metal element 12 is attached to the first metal element 11 or to the first metal element sections 11', the bridge sections BA are removed, for example by etching the entire surface of the side of the second metal element 12 facing away from the ceramic element 30 or by selectively removing the bridge sections BA. This allows for the final separation of the individual metallization sections 10 from each other after the second metal element 12 has been arranged and attached to the first metal element 11 by removing the bridge sections BA.

[0056] In Fig. Figure 4 is a method for producing a metal-ceramic substrate 1 according to a fourth preferred embodiment. In this process, it is specifically provided that a second metal element 12 is attached to the first metal element 11 of a metal-ceramic pre-substrate 1', wherein the second metal element 12 itself constitutes a back-side metallization 20 of a metal-ceramic pre-substrate 1', in particular with several second metal element sections 12". Specifically, the metal-ceramic pre-substrate 1' each provides a ceramic element 30 or a further ceramic element 30', on the opposite sides of which first metal element sections 11' and a back-side metallization 20 are provided. By appropriate structuring, in particular by creating protrusions 25 in the back-side metallization 20 of the metal-ceramic pre-substrate 1, it is thus possible to join the two metal-ceramic pre-substrate 1' together.The protrusions 25 on the back side of one pre-substrate 1' engage in the recess 24 on the top side of the first metal element 11 or the first metal element sections 11' on the component side of the metal-ceramic pre-substrate 1' to achieve a positive fit along a direction parallel to the main extension direction HSE. This advantageously makes it possible to provide, in the finished state, a metal-ceramic substrate 1 which, in addition to a ceramic element 30, has a further ceramic element 30', wherein a metallic intermediate layer is formed between the ceramic element 30 and the further ceramic element 30'.

[0057] In Fig. Figure 5 describes a method for producing a metal-ceramic substrate 1 according to a fifth exemplary embodiment of the present invention. This embodiment corresponds to the Fig. 5 essentially those in the Fig. 3a - 3d, wherein the second metal element 12 has a first section A1 and a second section A2, which are connected to each other via a bridge section BA. In contrast to the embodiment from the Fig. In sections 3a and 3b, it is specifically provided that the side surfaces 15 of the individual sections or metal elements, i.e., firstly, metal element 11 and secondly, metal element 12, have individual profiles and, in particular, do not run parallel to the stacking direction S. For example, it is conceivable that the side surfaces 15 extend obliquely to the main extension plane HSE and the stacking direction S. The side surfaces 15 can be curved and / or, in particular, have several concave sections. This advantageously makes it possible to individualize the side surfaces 15 in the manufactured metal-ceramic substrate 1 and, in particular, to adapt them in such a way that particularly advantageous conditions for the thermal shock resistance of the entire metal-ceramic substrate 1 are achieved.

[0058] In the Fig.Figure 6 describes a method for producing a metal-ceramic substrate 1 according to a sixth exemplary embodiment of the present invention. In contrast to the previous embodiments, the first metal element 11 and the second metal element 12 are formed on the back side of the ceramic element 30, i.e., on the cooling side opposite the component side. In particular, recesses 24 are provided in the back side metallization 20, which allow corresponding fins or a fin structure to be inserted as the second metal element 12 into the back side metallization 20, which functions as the first metal element 11. The advantages resulting for the component metallization 10 can be applied analogously to the approach on the back side of the metal-ceramic substrate 1.In particular, the connection of fins or a fin structure as a second metal element 12 to the first metal element 11, which is already connected to the ceramic element 30, allows for advantageous design freedom in the formation of metal-ceramic substrates 1, especially its cooling structure. Reference symbol: 1 Metal-ceramic substrate 10 (Component) Metallization 10' metal section 11 first metal element 11' first metal element section 12 second metal element 12' further second metal element 12" second metal element sections 15 side surfaces 18 Isolation trenches 20 Backside metallization 24 Exclusion 25 Survey 28 Expansion recess 30 ceramic elements 30' additional ceramic element HSE Main Extension Level S Stacking direction A1 first section A2 second section BA Bridge section B Width Total thickness D1 first thickness D2 second thickness D3 third thickness

Claims

[1] Method for producing a metal-ceramic substrate (1), comprising - Providing a ceramic element (30), a first metal element (11) and a second metal element (12), wherein the ceramic element (30) extends substantially along a principal extension plane (HSE), - Bonding the first metal element (11) to the ceramic element (30), particularly at a temperature above 500 °C, wherein the first metal element (11) and the ceramic element (30) are arranged one above the other in a stacking direction (S) that is perpendicular to the principal extension plane (HSE), and - Connecting the second metal element (12) to the first metal element (11) to form a metallization (10, 20), in particular a component metallization (10) and / or a backside metallization (20), wherein, after arranging the second metal element (12) on the first metal element (11), the first metal element (11) and the second metal element (12) interact in a form-fitting manner in a direction parallel to the principal extension plane (PEP), characterized by , that the first metal element (11) is structured to form first metal element sections (11') after the first metal element (11) is attached to the ceramic element (30). [2] Method according to claim 1, wherein the second metal element (12) and / or the first metal element (11) has at least one projection (25) and / or at least one recess (24) to form the positive locking in a direction parallel to the principal extension plane (HSE). [3] Method according to one of the preceding claims, wherein the first metal element (11) and the second metal element (12) are connected to each other via a plug-in mechanism when arranged one above the other. [4] Method according to claim 1, wherein the second metal element (12) and a further second metal element (12') are attached to different first metal element sections (11'). [5] Method according to one of the preceding claims, wherein the second metal element (12) has a first section (A1) and a second section (A2) for connection to different first metal element sections (11'), wherein the first section (A1) and the second section (A2) are connected to each other via a bridge section (BA), wherein the bridge section (BA) is preferably at least partially removed, in particular after the second metal element (12) has been connected to the first metal element (11). [6] Method according to one of the preceding claims, wherein the first metal element (11) has a first thickness (D1) dimensioned in the stacking direction (S) and the second metal element (12) has a second thickness (D2) dimensioned in the stacking direction (S), wherein the second thickness (D2) is greater than the first thickness (D1), in particular more than 2 times, preferably more than 4 times and particularly preferably more than 7.5 times as thick as the first thickness (D1). [7] Method according to one of the preceding claims, wherein the first metal element (11) and / or second metal element (12) has a side surface (15) which is not parallel and / or perpendicular to the principal extension plane (HSE) and which is preferably curved or bent at least in sections. [8] Method according to one of the preceding claims, wherein the metallization (10), in particular the component metallization, comprising the first metal element (11) and the second metal element (12), has a total thickness (D) greater than 1.5 mm, preferably greater than 2 mm and particularly preferably greater than 3 mm, wherein preferably a distance between two adjacent sections of the metallization (10) is less than 1.5 mm, preferably less than 2.5 mm and particularly preferably less than 3 mm.

Images