METHOD FOR PROCESSING A METAL-CERAMIC SUBSTRATE AND METAL-CERAMIC SUBSTRATE

Description

[0001] The present invention relates to a method for processing a metal-ceramic substrate, and to a metal-ceramic substrate with a predetermined breaking recess. Electronic modules are well known from the prior art, for example as power electronics modules. Such electronic modules typically utilize switchable or controllable electronic components that are interconnected via conductor tracks on a common metal-ceramic substrate. Essential components of the metal-ceramic substrate are an insulation layer, which in the case of the metal-ceramic substrate is made of a material comprising a ceramic, and a metallization layer, which is preferably structured to form conductor tracks and is formed on one component side of the metal-ceramic substrate.

[0002] Typically, a metal-ceramic substrate is realized as a large card, which is separated into smaller metal-ceramic substrates before or after structuring. Such large cards are processed using laser light to produce predetermined breaking recesses and / or separation points. The respective metal-ceramic substrates can then be prepared individually from the large card, e.g., by breaking them out. The use of ultrashort pulse lasers has proven advantageous in this regard, as described, for example, in WO 2017 / 108 950 A1. DE 10 2013 104 055 A1, which forms the basis for the preamble of claim 1, also discloses a further method for producing predetermined breaking lines in metal-ceramic substrates. EP 2 315 508 B1 also relates to the production of predetermined breaking lines.

[0003] Based on this prior art, the present invention aims to improve the production of predetermined breaking depressions in a metal-ceramic substrate, in particular in a large card.

[0004] This object is achieved by a method for processing a metal-ceramic substrate according to claim 1 and a metal-ceramic substrate according to claim 8. Further embodiments can be found in the subclaims and the description.

[0005] According to a first aspect of the present invention, there is provided a method for processing a metal-ceramic substrate, comprising: Providing a metal-ceramic substrate and forming a predetermined breaking recess in the metal-ceramic substrate, wherein the predetermined breaking recess has, along its direction of extension, at least a first section with a first depth and at least a second section with a second depth, wherein a second depth is realized which differs from the first depth.

[0006] Compared to the predetermined breaking depressions known from the prior art, the invention provides that the first section and the second section provide a first depth and a second depth for the predetermined breaking depression, whereby a bottom of the predetermined breaking depression is modulated in the direction of the extension of the predetermined breaking depression. It has been found that by appropriately modulating the bottom of the predetermined breaking depression, in particular with a first section having a first depth and a second section having a second depth different from the first depth, it is possible for the corresponding metal-ceramic substrates to be broken as flawlessly as possible and, on the other hand, to have a desirable stability that ensures safe transport without the metal-ceramic substrates unintentionally breaking during transport, in particular in the region of the predetermined breaking depression.This reduces the overall amount of rejects from metal-ceramic substrates that break incorrectly due to unintentional or untargeted breakage. These are preferably metal-ceramic substrates in the form of large cards.

[0007] In particular, it is provided that the first depth and / or second depth is measured from the bottom of the predetermined breaking depression in the first section or second section in a direction running perpendicular to the main extension plane up to an imaginary plane through which the top side of the metal-ceramic substrate or the ceramic layer also runs. A first section and a second section are meant in particular a section at the bottom of the predetermined breaking depression that does not have an oblique profile with respect to the main extension plane. In this case, the first section and / or the second section can also be point-shaped, in particular if the second section is immediately followed by an oblique profile of the bottom. For example, it can also be a zigzag-shaped profile at the bottom of the predetermined breaking depression.Preferably, it is provided that an inclined region is arranged between the first section and the second section, in which the bottom of the predetermined breaking recess runs obliquely to the main extension plane.

[0008] In other words: the first section and second section do not include, in particular, those sections of the predetermined breaking depression in which the base of the predetermined breaking depression runs obliquely with respect to the main extension plane. The base profiles of the predetermined breaking depression that are not part of the first section and second section, i.e. the oblique regions, can, for example, run perpendicular to a main extension plane and / or extend at an angle of between 30° and 60°, preferably 40° and 50° and particularly preferably between 42° and 48° to the main extension plane. In particular, the respectively obliquely running sections in the base of the predetermined breaking depression form an inclination that is essentially constant along the direction of extension, i.e. in particular do not deviate by more than 10%, preferably 5%, particularly preferably 2% from an average value of all inclination angles.

[0009] Preferably, the first depth assumes a value between 0.01 mm and 0.12 mm, preferably between 0.02 mm and 0.1 mm, and particularly preferably a value between 0.02 mm and 0.08 mm, while the second depth assumes a value between 0.01 mm and 0.16 mm, preferably between 0.02 mm and 0.12 mm, and particularly preferably a value between 0.02 mm and 0.1 mm.

[0010] Furthermore, the metal-ceramic substrate comprises at least one metal layer which is materially bonded to an upper side of a ceramic element or a ceramic layer, wherein the metal layer and the ceramic element extend along a main extension plane and are arranged one above the other along a stacking direction running perpendicular to the main extension plane.

[0011] Possible materials for the metal layer 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. Furthermore, it is preferably provided that the metal layer on the manufactured metal-ceramic substrate is surface-modified, in particular as component metallization. A possible surface modification is, for example, a sealing with a precious metal, in particular silver and / or gold, or (electroless) nickel or ENIG. ("electroless nickel immersion gold") or edge casting on the metal layer to suppress crack formation or widening is conceivable.

[0012] The ceramic element 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) as the material for the ceramic. It is also conceivable for the ceramic element to be designed as a composite or hybrid ceramic in which, in order to combine various desired properties, several ceramic layers which each differ in terms of their material composition are arranged one above the other and joined together to form a ceramic element. A ceramic which is as thermally conductive as possible is preferably used for the lowest possible thermal resistance.

[0013] The metal layer is preferably bonded to the insulating layer using an AMB process and / or a DCB process and / or hot isostatic pressing. Bonding using a diffusion bonding process or a thick-film coating process is also conceivable.

[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] It is preferably provided that during hot isostatic pressing, a container, in particular a metal container, is exposed in a heating and pressure device to a gas pressure of between 100 and 2000 bar, preferably 150 and 1200 bar, and particularly preferably 300 and 1000 bar, and a process temperature of 300°C up to a melting temperature of a metal layer and / or a further metal layer, in particular up to a temperature below the melting temperature of the metal layer and / or the further metal layer. It has advantageously been found that this makes it possible to bond a metal layer, i.e. the metal layer and / or the further metal layer of the metal container, to the ceramic element without reaching the required temperatures of a direct metal bonding process, for example a DCB or a DAB process, and / or without a solder base material that is used in active soldering. In addition, the use orThe use of appropriate gas pressure makes it possible to produce a metal-ceramic substrate with as few cavities as possible, i.e., without gas inclusions between the metal layer and the ceramic element. In particular, process parameters mentioned in DE 10 2013 113 734 A1 are used, and these are explicitly referred to in connection with hot isostatic pressing.

[0018] Preferably, it is provided that particles created during the creation of the predetermined breaking depression are suctioned away by means of a suction device. Such suction devices initiate a suction flow that is particularly configured such that the ceramic particles created during processing, in particular those created by sublimation, are suctioned away from the upper side of the metal-ceramic substrate. Preferably, the suction device is arranged substantially at the level of the metal-ceramic substrate and initiates a suction flow that runs substantially parallel to the main extension plane of the substrate, in particular near the substrate surface. As a result, the ceramic particles created by sublimation are suctioned away to the side during treatment with the laser pulses.

[0019] Preferably, it is preferably provided that the metal-ceramic substrate is arranged in a stationary manner during the formation of the predetermined breaking depression and / or that the laser light is moved over the metal-ceramic substrate to form the predetermined breaking depression, i.e., the metal-ceramic substrate is preferably arranged in a stationary manner during processing for the purpose of producing predetermined breaking depressions for separating the metal-ceramic substrates. "Stationary" means either fastened in one place or fastened in a rotatable / pivotable manner. For this purpose, for example, the metal-ceramic substrate, which is preferably provided as a large card, is fixed in a holding element. Such a holding element comprises, for example, a suction device which fixes the metal-ceramic substrate in the holding element during the process by means of a corresponding negative pressure on the underside of the metal-ceramic substrate. By fixing orThe stationary arrangement of the metal-ceramic substrate during the production of the predetermined breaking recesses advantageously allows for the creation of more finely structured and precisely shaped predetermined breaking recesses, particularly if multiple passes of the laser beam over the metal-ceramic substrate are planned. In this case, it is preferably provided that a laser beam of the USP system is moved along the planned paths of the predetermined breaking recesses, preferably in multiple passes. The laser beam moved over the metal-ceramic substrate has a processing speed of between 0.1 and 2 m per second, preferably between 0.8 and 1.5 m per second.

[0020] According to the invention, the first sections and the second sections are formed outside the intersection points of two predetermined breaking recesses. This ensures the advantageous breaking behavior across the entire large-scale card, and targeted weakening is not only achieved in areas of overlapping intersection points. In particular, it is provided that the first section or the second section is not formed exclusively at the intersection points of two predetermined breaking recesses. In particular, predetermined breaking recesses intersecting at an intersection point extend perpendicular to one another in order to divide the large-scale card into a checkerboard pattern using the predetermined breaking recesses.

[0021] Preferably, the ratio of a first depth T1 to a second depth T2 is between 0.05 and 1, preferably between 0.2 and 0.8, and particularly preferably between 0.4 and 0.6. It has been found that, particularly with a second depth that is approximately twice as large as the first depth, a metal-ceramic substrate with a predetermined breaking point can be provided that is particularly well-suited for handling and simultaneously exhibits sufficiently good breaking behavior along the predetermined breaking point.

[0022] According to the invention, the first depth in the first section remains substantially constant over a first length measured in the direction of the predetermined breaking recess, and / or the second depth in the second section remains substantially constant over a second length measured in the direction of the predetermined breaking recess. The production of a corresponding modulation in which, in particular, the first length and / or the second length remains constant over a certain period of time can be realized quickly and without great effort.

[0023] Preferably, the first length assumes a value between 0.05 mm and 5.0 mm, preferably between 0.05 mm and 2.0 mm and particularly preferably a value between 0.05 mm and 0.01 mm, while the second length assumes a value between 0.05 mm and 5.0 mm, preferably between 0.05 mm and 2.0 mm and particularly preferably a value between 0.05 mm and 0.01 mm.

[0024] Furthermore, it is particularly preferably provided that a ratio of the first length to the second length is less than 1.5, preferably less than 0.5 and particularly preferably less than 0.25.

[0025] In particular, it is particularly preferred if the first length approximately corresponds to the second length, resulting in a particularly symmetrical profile of the base of the predetermined breaking recess with regard to its modulation. In particular, the interval also includes ratios in which the first section is point-shaped and thus the ratio is essentially 0. In these embodiments, the base profile forms a substantially triangular shape in a cross-section that runs perpendicular to the main extension plane and through the direction of extension.

[0026] It is particularly preferred if a predetermined breaking recess is produced on the top and bottom sides of the metal-ceramic substrate, which are arranged substantially congruently with one another in a direction perpendicular to the main extension plane. It is conceivable that the first sections and the second sections on the top side are arranged at the same position or, as viewed in the direction of extension, offset from the corresponding first sections and second sections on the bottom side.

[0027] Preferably, the first section and the second section alternate periodically. In other words, along the direction of travel, the first section and the second section alternate continuously, apart from the connecting slopes of the bases of the predetermined breaking recess. In this case, sloped regions are preferably formed between the first section and the second section.

[0028] Preferably, the predetermined breaking recess has a third depth in a direction perpendicular to the direction of travel, which preferably differs from the first and / or second depth. This results in, for example, a W-shaped or W-like profile of the predetermined breaking recess in a plane or cross-section perpendicular to the direction of travel. Such a recess can be achieved, for example, by slightly offsetting the laser light during a few passes compared to the subsequent passes with the laser light that lead to the formation of the predetermined breaking recess.

[0029] Preferably, the predetermined breaking recess in the first section or second section has a trapezoidal or triangular shape in a plane running parallel to the direction of travel. This results in a substantially advantageous base contour for the predetermined breaking recess.

[0030] Preferably, the predetermined breaking recess is produced by machining using laser light, in particular an ultrashort pulse laser, wherein, as part of the formation of the predetermined breaking recess, the metal-ceramic substrate is subjected to a thermal treatment before, during, and / or after machining, wherein, in particular, cooling takes place, in particular after machining, at a cooling rate of less than 4° per minute, preferably less than 2° per minute, and particularly preferably less than 0.5° per minute. It has been found that targeted thermal treatment, in particular targeted cooling of the metal-ceramic substrate, can prevent thermomechanical stresses in the produced metal-ceramic substrate, thereby permanently improving the thermal shock resistance of the broken metal-ceramic substrate.

[0031] The USP laser is preferably a laser source that provides light pulses with a pulse duration of 0.1 to 800 ps, ​​preferably 1 to 500 ps, ​​particularly preferably 10 to 50 ps. It has proven particularly advantageous to use such pulses, particularly at processing speeds between 0.2 and 8 m / s, to produce predetermined breaking depressions or predetermined breaking points that exhibit a particularly favorable ratio between molten ceramic and crack formation within the predetermined breaking depressions, thereby ensuring particularly reliable and successful breaking along the predetermined breaking depressions without causing damage to the separated metal-ceramic substrate during breaking.In particular, compared to processing with a CO2 laser, lower stresses are introduced into the metal-ceramic substrate, which can influence the mechanical properties of the ceramic and can otherwise easily propagate, induced by the metallization of the metal-ceramic substrate. This can either cause rejection or at least affect the lifetime of the metal-ceramic substrate. It has been shown that this effect of using ultrashort pulse laser light is particularly pronounced when the use of pulsed laser light is accompanied by heat treatment. In particular, the success rate for breaking metal-ceramic substrates can be further improved.

[0032] The present invention further relates to a metal-ceramic substrate with a predetermined breaking recess, produced using the method according to the invention. All properties and advantages described for the method apply analogously to the metal-ceramic substrate. In particular, the metal-ceramic substrate, especially as a large card, is characterized in that it has a first section with a first depth and a second section with a second depth, wherein the first depth differs from the second depth.

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

[0034] It shows: Fig.1:schematic representation of a method for processing a metal-ceramic substrate according to a first exemplary embodiment of the present invention and Fig. 2a: Predetermined breaking recess according to the state of the art Fig. 2b: Predetermined breaking recess according to a second exemplary embodiment of the present invention and Fig. 2c: Predetermined breaking recess according to a third exemplary embodiment of the present invention

[0035] In Figure 1A method for processing a metal-ceramic substrate 1 according to a first preferred embodiment of the present invention is shown schematically. Such a metal-ceramic substrate 1 preferably serves as a carrier for electronic or electrical components that can be bonded to the metal-ceramic substrate 1. Essential components of such a metal-ceramic substrate 1 are a ceramic layer or a ceramic element extending along a main extension plane HSE and a metal layer bonded to the ceramic layer. The ceramic layer is made of at least one material comprising a ceramic. The metal layer and the ceramic layer are arranged one above the other along a stacking direction running perpendicular to the main extension plane HSE and, in a manufactured state, are integrally bonded to one another at least in regions via a bonding surface.Preferably, the metal layer is then structured to form conductor paths or connection points for the electrical components. For example, this structuring is etched into the metal layer. However, a permanent bond, particularly a material bond, must be formed between the metal layer and the ceramic layer beforehand.

[0036] To permanently bond the metal layer to the ceramic layer, a system for producing the metal-ceramic substrate, particularly using a DCB or DAB bonding process, includes a furnace in which a stacked arrangement of a ceramic layer and at least one metal layer is heated, thus creating the bond. For example, the metal layer is made of copper, and the metal layer and the ceramic layer are bonded together using a DCB (direct copper bonding) bonding process. Alternatively, the metal layer can be bonded to the ceramic layer using an active soldering process or a thick-film process. Bonding using a hot isostatic process or diffusion bonding is also conceivable.

[0037] After bonding, in particular using a DCB process, a flash soldering process, a diffusion bonding process, hot isostatic pressing, and / or a thick-film process, the metal-ceramic substrate 1 is provided as a large card. Such large cards are to be singulated in the subsequent process in order to provide individualized metal-ceramic substrates 1. For such singulation, it is preferably provided that the large card is processed using laser light 10, in particular using ultrashort pulse laser light. In this case, it is possible to immediately realize a separation using the laser light 10 and / or to form a predetermined breaking recess 7, along which the large card is broken in the subsequent process, forming the individualized metal-ceramic substrates 1. Those skilled in the art understand an ultrashort pulse laser to mean, in particular, laser sources that emit laser pulses whose pulse length is less than one nanosecond.Preferably, the pulse duration is between 0.1 and 100 ps. Furthermore, it is conceivable for the pulse duration to be in the femtosecond range, i.e., the pulse length is 0.1 to 100 fs. Alternatively, the use of a CO2 laser is also conceivable. In the method described in . Figure 1 In the illustrated embodiment, the metal-ceramic substrate 1 is arranged in a holding element 40.

[0038] In particular, it is provided that the metal-ceramic substrate 1 is arranged in a stationary manner by means of the holding element 40. In order to produce a predetermined breaking recess 7, which in particular has a specific profile along a profile direction V across the metal-ceramic substrate 1, it is provided that laser light 10 or a laser beam is moved across the metal-ceramic substrate 1. In other words: instead of moving the metal-ceramic substrate 1 relative to the laser light 10 or its alignment, it is preferably provided that the alignment of the laser light 10 or laser beam is carried out in such a way that the laser light 10 moved across the metal-ceramic substrate 1 produces a predetermined breaking recess 7 and / or a separating or cutting line at the respective points of impact. It is conceivable that the predetermined breaking recess 7 is continuous and / or interrupted, ie the predetermined breaking recess 7 is present as a perforation.The laser light 10 moving across the metal-ceramic substrate 1 has a processing speed between 0.1 and 2 m / s, preferably between 0.8 and 1.5 m / s. Alternatively, it is conceivable that the metal-ceramic substrate 1 is displaced to change the position of the laser light 10 impinging on the metal-ceramic substrate 1.

[0039] To align the laser light 10, it is particularly provided that the laser light 10 is directed onto a mirror element 30. The laser light 10 is reflected by the mirror element 30 and then strikes the metal-ceramic substrate 1. In this case, it is particularly provided that the mirror element 30 is pivotally mounted, in particular pivotably mounted about at least two axes, in order to align the laser light 10 onto a specific treatment area or specific areas on the metal-ceramic substrate 1. Furthermore, it is preferably provided that a lens 20, preferably an fΘ lens, is arranged between the mirror element 30 and the metal-ceramic substrate 1. In particular, the lens 20 extends along a plane running substantially perpendicular to the direction of incidence of the laser light 10, essentially over a length that corresponds to the length and / or width of the metal-ceramic substrate 1, in particular as a large card.In other words, the laser light 10 traveling over the metal-ceramic substrate 1 always passes through the same lens 20, regardless of the processing area.

[0040] It has proven particularly advantageous to use a lens 20 whose focal length is greater than 300 mm, preferably greater than 350 mm, and particularly preferably greater than 420 mm. Arranging the lens 20 at a distance from the metal-ceramic substrate 1 that essentially corresponds to the focal length of the lens 20 then makes it possible to produce predetermined breaking points or predetermined breaking depressions 7 that are comparatively slightly inclined with respect to a vertical direction running perpendicular to the main extension plane HSE of the metal-ceramic substrate 1. Otherwise, an angle of inclination that essentially results in V-shaped or notch-shaped predetermined breaking depressions 7 would have to be expected. This applies in particular to predetermined breaking depressions 7 that arise at the edge of the metal-ceramic substrate 1. Such an inclined position is caused in particular by the fact that the laser light 10 orthe laser beams cannot impinge uniformly perpendicularly on the metal-ceramic substrate 1 over the entire extent of the metal-ceramic substrate 1.

[0041] However, by using a focal length greater than 300 mm, this inclination is reduced, particularly in the edge regions of the metal-ceramic substrate 1, such that an angle of inclination, measured or relative to the perpendicular direction of the metal-ceramic substrate 1, is less than 12°, particularly preferably less than 10°. In particular, it should be noted that a deviation of the angle of inclination compared to the orientation of the predetermined breaking depression 7 in the center of the metal-ceramic substrate 1 does not exceed 12°. This advantageously makes it possible to create predetermined breaking depressions 7 whose fracture behavior is essentially homogeneously distributed over the entire metal-ceramic substrate 1.

[0042] Furthermore, a suction device 25 is provided. The suction device 25 is arranged laterally offset from the metal-ceramic substrate 1 or the holding element 40. The suction device 25 has an opening through which a gas can be sucked in. In particular, the suction device 25 serves to suck sublimated particles from the surface or top side of the metal-ceramic substrate 1 during the processing process. These sublimated ceramic particles are the result of plasma formation or a plasma flame 6, which is created during the processing of the metal-ceramic substrate 1 using ultrashort pulse laser light. In addition to a lateral arrangement, an arrangement of the suction device 25 above the metal-ceramic substrate 1 to be divided is also conceivable, with the opening directed towards the metal-ceramic substrate 1.

[0043] In particular, it is provided that the metal-ceramic substrate 1 is subjected to a temperature treatment within the scope of producing the predetermined breaking recess 7 before processing and / or during processing and / or after processing with the laser light 10 to produce the predetermined breaking recess 7. In particular, the temperature treatment is designed to control the temperature development in the metal-ceramic substrate 1 in such a way that sudden or severe temperature changes are avoided. This advantageously reduces the formation of thermomechanically induced stresses in the metal-ceramic substrate 1. This, in turn, leads to an improvement in the thermal shock resistance of the manufactured, in particular divided, metal-ceramic substrate 1, a reduction in the tendency to conchoidal fracture, and a reduction in the tendency to cracks, in particular vertical cracks.

[0044] In particular, the skilled person understands "during the production of the predetermined breaking recess" to mean that the temperature increase occurs for processing with the laser light 10 and does not refer to temperature increases that occur beforehand, for example, during bonding of the metal layer to the ceramic layer in a DCB process and / or active soldering process, or after production of the metal-ceramic substrates 1, for example, due to heat generation during operation. For this purpose, for example, the metal-ceramic substrate 1 is heated within 15 minutes, preferably 10 minutes, and particularly preferably 5 minutes, before processing 103 of the metal-ceramic substrate 1 to produce the predetermined breaking recess 7. The same applies to the temperature treatment after processing with the laser light 10.

[0045] For example, the metal-ceramic substrate 1 is heated before processing or before processing with the laser light 10, in particular to a temperature greater than 40°C, preferably greater than 80°C, and particularly preferably greater than 150°C. In particular, it is provided that the heating 102 results in the heat input, which occurs through the laser pulse itself and preferably results in a short-term heat input, being relatively reduced. In particular, the temperature treatment is carried out at a heating rate of less than 5°C / min, preferably less than 3°C / min, and particularly preferably less than 0.5°C / min.

[0046] Preferably, cooling takes place at a cooling rate of less than 4 °C / min, preferably less than 2 °C / min, and particularly preferably less than 0.5 °C / min. A temperature treatment during the processing of the metal-ceramic substrate 1 is to be understood in particular as meaning that, for example, when passing over a position multiple times, the laser beam or the laser light 10 passes the same position in a first pass and then in a second pass. By a specifically adjustable time interval between the first pass and the second pass, a targeted cooling of the metal-ceramic substrate 1 can be caused during processing. Alternatively or additionally, it is also conceivable that, in addition to setting the time interval until the second pass, the metal-ceramic substrate 1 is additionally cooled.This allows the time interval until the second pass to be shortened, thereby accelerating the entire manufacturing process for producing or processing the metal-ceramic substrate 1 to form the predetermined breaking recess 7.

[0047] In order to carry out a targeted temperature treatment of the metal-ceramic substrate 1, it is conceivable, for example, that the holding element 40 has, for example, heating elements 50, which are preferably arranged in a direction running perpendicular to the main extension plane HSE below the predetermined breaking depressions 7 or the planned predetermined breaking depressions 7. Corresponding heating elements 50 can be arranged, for example, within the holding element 40 and / or mounted on an outer side of the holding element 40. For example, the heating elements 50 directly border the metal-ceramic substrate 1 when the holding element 40 is equipped with the metal-ceramic substrate. Furthermore, it is preferably provided that the holding element 40 fixes the metal-ceramic substrate 1 in a form-fitting and / or force-fitting manner in a direction running parallel to the main extension plane HSE.As a result, the holding element 40 can also be used to position the metal-ceramic substrate 1. As an alternative to the formation of heating elements 50 inside or on the outside of the holding element 40, it is also conceivable and / or additionally conceivable that the entire holding element 40 is heated and / or deliberately cooled to heat and / or cool the metal-ceramic substrate 1. For this purpose, the holding element 40 is preferably made of a material with a comparatively high thermal conductivity, in particular a thermal conductivity greater than 100 W / mK, preferably greater than 200 W / mK, and particularly preferably greater than 400 W / mK.

[0048] Preferably, the holding element 40 is heated, for example, by means of heating coils or heating elements 50, which are regularly and / or irregularly distributed in or on the holding element 40. Preferably, the heating coils or heating elements 50 are arranged at least partially congruently below the planned predetermined breaking recess 7 in a direction perpendicular to the main extension plane HSE.

[0049] In Figure 2a1 shows a predetermined breaking depression 7 according to the prior art. In particular, it is a sectional view along the direction V, through which a profile of the predetermined breaking depression 7, in particular at its base or bottom, can be seen. The predetermined breaking depression 7, which is in particular embedded in the ceramic layer, has a first depth T1, measured in a direction running perpendicular to the main extension plane HSE between an upper side OS of the metal-ceramic substrate 1, in particular the ceramic layer of the metal-ceramic substrate 1, into which the predetermined breaking depression 7 is embedded, and the bottom. In this case, the first depth T1 is in particular always related to a plane that conceptually continues the upper side OS of the ceramic layer, i.e. a plane that runs parallel to the upper side OS.The prior art embodiment shows that the predetermined breaking recess 7 according to the prior art has a substantially constant first depth T1, apart from the beginning and end of the profiles extending obliquely to the main extension plane. A person skilled in the art understands a first constant depth T1 to be one that varies by less than 10%, less than 5%, and less than 2% along the extension direction V.

[0050] In Figure 2b A predetermined breaking recess 7 according to a preferred embodiment of the present invention is shown. In particular, the predetermined breaking recess 7 of the Figure 2ba first section A1 and a second section A2, wherein a first depth T1 of the first section A1 differs from a second depth T2 of the second section A2. In this case, a first section A1 or second section A2 is understood in particular to be a partial section of the predetermined breaking recess 7 or of the base of the predetermined breaking recess 7 which runs along the direction V essentially parallel to the main extension plane HSE. In other words: excluding the first sections A1 and second sections A2 in the predetermined breaking recess 7 are the sections at the base or of the predetermined breaking recess 7 which run essentially obliquely to the main extension plane HSE and which, for example, connect the upper side OS to the first section A1 and / or the first section A1 to the second section A2.

[0051] In the Figure 2bIn the embodiment shown, a first length L1 of the first section A1, measured parallel to the direction V, corresponds essentially to a second length L2 of the second section A2. Figure 2bIt can be seen that the second depth T2 of the second section A2 is essentially twice as great as the first depth T1 in the first section A1. Furthermore, it is preferably provided that the first section A1 and the second section A2 alternate in the direction of extension V and thereby form a periodic pattern of the bottom of the predetermined breaking depression 7. It has been found that the formation of predetermined breaking depressions 7 with different depths, ie at least a first depth T1 and a second depth T2 for a first distance A1 and a second section A2, is suitable for providing sufficient stability for the metal-ceramic substrate 1, in particular in the form of a large card, which in particular allows its transport. At the same time, the different depths T1, T2 allow almost exclusive breakage along the predetermined breaking depression 7.

[0052] In particular, it is provided that the bottom of the predetermined breaking recess 7 is continuously modulated along the direction of extension V, in particular continuously periodically, in order to form a first section A1 and a second section A2. In particular, it is provided that the bottom has a trapezoidal and / or triangular cross-section in the sectional view that runs perpendicular to the main extension plane HSE and runs through the direction of extension V.

[0053] To produce such a predetermined breaking depression 7, it is conceivable, for example, that the laser light 10 is moved over the ceramic layer more frequently in the second sections A2 than in the first section A1. Alternatively, it is conceivable that, after producing a depression with a first depth T1, a shading element, in particular a correspondingly patterned shading element, is placed on the ceramic layer so that light only hits the ceramic layer through the unshaded areas in the shading element, causing the ceramic material to be removed there. In this way, correspondingly modulated predetermined breaking depressions 7 can be realized.

[0054] In the Figure 2cIn the illustrated embodiment of the present invention, it is further provided that the second length L2 of the second section A2 is greater than the first length L1 of the first section A1. In particular, it is provided that the first section A1 is essentially point-shaped, so that a triangular shape is formed at the bottom of the predetermined breaking recess 7. List of reference symbols:

[0055] 1Metal-ceramic substrate 6Plasma flame 7Predetermined break point 10Laser light 20Lens 25Suction device 30Mirror element 50Heating element A1First section A2Second cut T1First depth T2Second depth VDirection of travel OSTop side HSEMain extension plane

Claims

1. Method for processing a metal-ceramic substrate (1), in particular for forming a predetermined breaking recess, comprising: - providing a metal-ceramic substrate (1) and - forming a predetermined breaking recess (7) in the metal-ceramic substrate (1) wherein the predetermined breaking recess (7) hasat least a first section (A1) with a first depth (T1) and at least a second section (A2) with a second depth (T2) along its direction of extension, wherein a second depth (T2) is formed that differs from the first depth (T1), characterised in that the first sections (A1) and the second sections (A2) are formed outside of the intersection points of two predetermined breaking recesses (7), the first depth (T1) in the first section (A1) via a first length (L1) measured in the direction of extension (V) of the predetermined breaking recess (V) and the second depth (T2) in the second section (A2) via a second length (L2) measured in the direction of extension (V) of the predetermined breaking recess (V) remain essentially constant.

2. Method according to claim 1, wherein a ratio of a first depth (T1) to a second depth (T2) has a value between 0.2 and 0.8, preferably between 0.3 and 0.7, and most preferably between 0.4 and 0.6.

3. Method according to claim 1, wherein a ratio of the first length (L1) to the second length (L2) is less than 1.5, more preferably less than 0.5 and most preferably less than 0.25.

4. Method according to any of the preceding claims, wherein the first section (A1) and the second section (A2) periodically alternate.

5. Method according to one of the preceding claims, wherein the predetermined breaking recess (7) has a third depth in a direction perpendicular to the direction of extension (V), which depth preferably differs from the first depth (T1) and / or the second depth (T2).

6. Method according to one of the preceding claims, wherein the predetermined breaking recess (7) has a trapezoidal or triangular shape in a plane running parallel to the direction of progression (V).

7. Method according to one of the preceding claims, wherein the predetermined breaking recess (7) is formed by processing by means of laser light (10), in particular an ultrashort pulse (UKP) laser, wherein in the context of forming the predetermined breaking recess (7), the metal-ceramic substrate (1) is subjected to a temperature treatment before the processing, during the processing and / or after the processing, wherein cooling, in particular after the processing, is carried out at a cooling rate of less than 4°C / min, preferably less than 2°C / min and most preferably less than 0.5°C / min.

8. Metal-ceramic substrate having a predetermined breaking recess (7) formed by a method according to one of Claims 1 to 6.