Method for processing metal-ceramic substrates

Abstract

To provide a method for processing a metal ceramic substrate.SOLUTION: A method for machining a metal ceramic substrate (1) includes the steps of: providing the metal ceramic substrate (1), the metal ceramic substrate (1) including one or more metal layers and a ceramic element which extend along a principal surface (HSE) and are vertically arranged along a lamination direction (S) which extends perpendicularly to the principal surface (HSE); and forming a recess (15), particularly a through-recess (15), in the metal ceramic substrate (1) by machining using a laser beam (10), particularly ultrashort pulse (USP) laser.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Electronic modules are known in the prior art, for example, as power electronic modules. Such electronic modules typically use switchable or controllable electronic components interconnected via conductor tracks to a common metal-ceramic substrate. The essential components of a metal-ceramic substrate are an insulating layer made of a material containing ceramic in the case of a metal-ceramic substrate, and a metallization layer structured and formed on one component side of the metal-ceramic substrate so as to preferably form conductor tracks.

[0003] Typically, a metal-ceramic substrate is realized as a large card that separates into small metal-ceramic substrates before and after structuring. Such large cards are processed by a laser beam so as to generate predetermined breaking lines and / or separation points. Each metal-ceramic substrate can then be provided separately from the large card, for example, by breaking the metal-ceramic substrate. The use of an ultrashort pulse laser has been shown to be advantageous here, as described for the examples in Patent Document 1.

[0004] From Patent Document 2, a method for processing a workpiece using a laser beam is known, and the workpiece is placed on a stage. Patent Document 3 also relates to the generation of drill holes by a laser beam.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Based on prior art, the present invention aims to improve the processing of metal-ceramic substrates. [Means for solving the problem]

[0007] This objective is achieved by the method for processing a metal-ceramic substrate according to claim 1, by an apparatus suitable for the method according to claim 9, and by a metal-ceramic substrate produced by such a method according to claim 10. Further embodiments are taken from the dependent claims and descriptions.

[0008] A method for processing a metal ceramic substrate according to a first aspect of the present invention, A process for providing a metal-ceramic substrate, wherein the metal-ceramic substrate comprises one or more metal layers and one ceramic element, which are arranged vertically along a stacking direction that extends perpendicular to the main surface and extends along the main surface. A method is provided which includes the step of forming recesses, particularly through-recesses, in the metal ceramic substrate by processing with laser light, particularly an ultrashort pulse laser.

[0009] In contrast to methods known from the prior art, laser beams (particularly UKP lasers) are used to form recesses. In this case, those skilled in the art will understand that the recess is an area that is not metal and / or ceramic, preferably completely surrounded or enclosed by a metallic ceramic substrate, preferably more than 50%, preferably more than 75%, in one plane. For example, the recess is surrounded by a curved or polygonal contour generated by the laser beam. In this case, it is envisioned that the recess is used, for example, as a through-hole plating after a suitable film and / or solder paste and / or other conductive material has been introduced, and / or as an area where fastening elements such as screws and / or bolts engage to secure the metallic ceramic substrate to a housing and / or another component. Fabrication using laser beams has been shown to be advantageous, particularly in terms of quality and the time required to form the recess. For example, by using ultrashort pulse laser beams, it is possible to reduce the number of post-processing steps for the metallic ceramic substrate. In addition, it is advantageously possible, for example, to guide the laser beam to scan across the top surface of the metallic ceramic substrate using a corresponding mirror element to achieve the desired shape and contour of the recess.

[0010] It is particularly preferable that the recess extends throughout the entire metal-ceramic substrate, that is, from the top surface of the metal-ceramic substrate to the back surface of the metal-ceramic substrate. Preferably, the metal-ceramic substrate is held or fixed by support elements or retaining elements during laser treatment.

[0011] Furthermore, the metal-ceramic substrate comprises one or more metal layers bonded to the upper surface of the ceramic layer. The metal and ceramic layers are arranged vertically along a lamination direction that extends perpendicular to the main surface and extends along the main surface. Possible materials for one or more metal layers include copper, aluminum, molybdenum, and / or alloys thereof, as well as thin layers such as CuW, CuMo, CuAl, AlCu, and / or CuCu, particularly sandwich structures of a first copper layer and a second copper layer. The particle size of the first copper layer is different from that of the second copper layer. It is even more preferable that one or more metal layers are modified surfaces. Possible surface modifications include sealing with, for example, a precious metal, particularly silver and / or gold, or ENIG (electroless nickel / substitution gold plating), or edge sealing in the first or second metallization layer, to suppress crack formation or expansion.

[0012] For example, a ceramic element is one or more ceramic layers, or a composite comprising one or more ceramic layers. Preferably, one or more of the ceramic layers include Al2O3, Si3N4, AlN, HPSX ceramics (i.e., ceramics with an Al2O3 matrix containing x percent ZrO2, e.g., Al2O3=HPS9 with 9% ZrO2 or Al2O3=HPS25 with 25% ZrO2), SiC, BeO, MgO, high-density MgO (>90% theoretical density), TSZ (tetragonal stable zirconia), and ZTA as a material for ceramics. It is also conceivable that the insulating layer be designed as a composite or hybrid ceramic, where several ceramic layers, each differing in its own material composition, are arranged vertically and bonded together to form an insulating layer that combines various desired attributes. Preferably, ceramics with the highest possible thermal conductivity are used for the lowest possible thermal resistance.

[0013] A ceramic element or ceramic layer is understood to preferably mean a material that does not contain glass or consists of more than 50% glass. Therefore, the ceramic element is preferably a glass-free ceramic element. Preferably, the recess is created by repeatedly traversing a metal-ceramic substrate along the same contour.

[0014] Preferably, the metal layer is bonded to the insulating layer by AMB treatment and / or DCB treatment. Those skilled in the art will understand that "DCB treatment" (direct copper bonding technique) or "DAB treatment" (direct aluminum bonding technique) is a process that functions to bond a metal layer or sheet (e.g., a copper sheet or foil or an aluminum sheet or foil) to each other and / or to a ceramic or ceramic layer using a metal or copper sheet or metal or copper foil having a layer or coating (fusion layer) on its surface. In this process, as described in U.S. Patent No. 3,744,120 or German Patent No. 2,319,854, for example, the layer or coating (fusion layer) forms a eutectic at a melting temperature below the melting temperature of the metal (e.g., copper). As a result, by placing the foil on the ceramic and by heating all the layers, the ceramic and the layers can be bonded to each other by melting the metal or copper only in the regions of the fusion layer or oxide layer.

[0015] In particular, the DCB treatment then includes, for example, the following steps: • Oxidizing the copper foil so that a uniform copper oxide layer is formed; • Placing the copper foil on the ceramic layer; • Heating the composite to a treatment temperature between approximately 1025 and 1083°C (for example, up to 1071°C); • Cooling to room temperature. The intended process involves activated soldering (for example, bonding a metal layer or metal foil, particularly a copper layer or copper foil, to a ceramic material), a process also used to produce metal-ceramic substrates. Bonding is achieved at temperatures between approximately 650 and 1000°C using a brazing alloy containing active metals in addition to main components such as copper, silver, and / or gold, between the metal foil (e.g., copper foil) and the ceramic substrate (e.g., aluminum nitride ceramic). These active metals, for example, one or more elements from the group Hf, Ti, Zr, Nb, and Ce, establish the connection between the brazing alloy and the ceramic through a chemical reaction. Conversely, the connection between the brazing alloy and the metal is a metal-to-metal brazing connection. Alternatively, thick-film treatment is also considered for bonding.

[0016] In a preferred embodiment, the laser beam is directed to a metal-ceramic substrate by one or more pivotable mirror elements or reflectors, and in particular, moved on the metal-ceramic substrate by one or more pivotable mirror elements or reflectors. A corresponding scanning device makes it possible to move, for example, the laser beam or laser light as precisely as possible at a position on the planned path of a future recess (i.e., the processing area). In this case, it is particularly expected that the one or more mirror elements are matched to the pulse duration and / or wavelength of the laser light used to reduce losses during reflection in the one or more mirror elements. Furthermore, it is assumed that the one or more mirror elements are concave mirrors and / or dielectric mirrors so as to focus the laser beam at least partially already, preferably before and after passing through an additional lens. The intensity of the incident laser pulse can be advantageously increased by focusing, particularly by the lens. Furthermore, it is particularly preferred that the one or more mirror elements are pivotable around two or more axes. This ensures that every point on the upper surface of the metal-ceramic substrate can be detected by the laser beam, depending on the orientation of each mirror element. Preferably, exactly one mirror element is involved.

[0017] Preferably, the UKP laser is a laser source that provides the optical pulse with a pulse duration of 0.1 to 800 ps, ​​preferably 1 to 500 ps, ​​more preferably 10 to 50 ps. In particular, it has been found to be particularly advantageous to use such pulses having the above processing speeds to generate a predetermined fracture line or fracture point having a particularly favorable ratio between molten ceramic and crack formation within the recess and / or predetermined fracture line. This ensures, for example, a reliable or successful fracture along the predetermined fracture line, particularly in the case of a predetermined fracture line, without causing damage to a single metallic ceramic substrate during fracture. Preferably, the predetermined fracture line for a recess is realized, for example, by the same laser system.

[0018] Preferably, the cross-section of a recess extending parallel to the main surface is larger than the cross-section of the laser beam measured along the same plane. Preferably, the cross-section of the recess has a first diameter, and the cross-section of the laser beam has a second diameter, where the ratio of the second diameter to the first diameter is less than 0.2, preferably less than 0.1, and more preferably less than 0.05. In this way, for example, by moving a laser beam along the upper surface of a metallic ceramic substrate, it is possible to form a cutting contour that forms the shape of the subsequent cross-section of the recess. In particular, such processing functions to form a recess through which a fixing device or fixture passes for fixing in a later manufactured metallic ceramic substrate. Such recesses having correspondingly larger cross-sections generally function to form through-plating, but preferably are provided simply to fix the metallic ceramic substrate to another component.

[0019] It is particularly preferable that the laser beam is directed by a lens towards the processing area of ​​the metal-ceramic substrate. The distance between the lens and the upper surface of the metal-ceramic substrate changes during processing. In particular, the distance between the lens and the upper surface of the metal-ceramic substrate refers to the area outside the area where the recess is formed, i.e., outside the processing area. By redrawing the distance between the lens and the upper surface of the metal-ceramic substrate, it is possible to advantageously take into account the fact that during the process, ablation is performed on the metal-ceramic substrate, and as a result, the lens focus falls on the area where ablation of the metal-ceramic substrate material has already been performed, without the distance between the lens and the upper surface of the metal-ceramic substrate decreasing accordingly. The corresponding coordinate change of the distance between the lens and the upper surface of the metal-ceramic substrate can advantageously ensure that the focal point of the laser beam is located directly above and / or directly below the area of ​​the metal-ceramic substrate material being ablated or the boundary layer being ablated. For this purpose, the distance between the lens and the metal-ceramic substrate preferably changes along the stacking direction. In particular, the (total) change in the distance between the lens and the metal-ceramic substrate essentially corresponds to the thickness of the metal-ceramic substrate dimensionally determined in the stacking direction.

[0020] Furthermore, it is anticipated that the inclination of the laser beam will change during processing. This allows, for example, the inner contour of the recess to take on a desired shape. It is also anticipated that the recess may be formed such that a stepped contour is realized inside the recess. This allows, for example, the head of the fixture to provide an empty area on the upper surface of the metal-ceramic substrate, which is a countersunk hole. Here, it may be advantageous to provide, for example, different inclination angles inside the recess in a first section, and to provide this first section to conform to the shape of the head of the fixture.

[0021] Preferably, the laser beam is incident perpendicularly on the metal-ceramic substrate at least occasionally, preferably throughout the entire process. This allows for the creation of cylindrical recesses having a substantially constant cross-section when viewed in the stacking direction. For example, the inward slope of the recess with respect to the direction perpendicular to the main surface is less than 10%, preferably less than 5%, and more preferably less than 2.5%.

[0022] Preferably, the metal ceramic substrate is processed exclusively in areas of the metal ceramic substrate that are free of metal. For example, the recesses are intended to be generated by repeatedly traversing the metal ceramic substrate along the same contour.

[0023] For example, it is also envisioned that additional laser light is provided and that the recesses are formed by the laser light and the additional laser light. This can significantly accelerate the generation of the recesses. It is envisioned that the laser light and the additional laser light process the metal ceramic substrate at different points of a common contour simultaneously. Both the laser light and the additional laser light follow the common contour so as to form recesses.

[0024] Furthermore, it is preferable that a focal length of the lens exceeding 300 mm is used. At a relatively large focal length, particularly exceeding 300 mm, preferably exceeding 350 mm, more preferably exceeding 430 mm, it is advantageously possible to use the laser light so as to generate a predetermined breaking line with a relatively small inclination with respect to the direction extending perpendicular to the main surface, in addition to the recesses. This advantageously ensures a uniform fracture behavior of the metal ceramic substrate, particularly over the entire large card. Preferably, the same laser system is used to provide the laser light that, on the one hand, generates a predetermined breaking line and, on the other hand, generates recesses in the metal ceramic substrate. By changing the laser parameters and / or using filters, the characteristics for generating a predetermined breaking line on the one hand and recesses on the other hand can preferably be varied.

[0025] In particular, the distance between the lens and the metal ceramic substrate never falls below the focal length of the lens by a value greater than the thickness of the metal ceramic substrate, particularly when the lens and / or the metal ceramic substrate move towards each other. This can ensure that the laser light always remains focused, particularly when the material is ablated layer by layer and the focus of the laser light is tracked.

[0026] Preferably, the distance changes continuously or in steps. In particular, it is assumed that the recess depth, especially the current recess depth, is measured concurrently with the processing of the metal-ceramic substrate to generate the recess, and as a result, the distance between the lens and the metal-ceramic substrate can be set according to the current value of the recess depth. For example, the recess depth is optionally measured by a camera and / or another laser system. Alternatively, or in addition to this, it is assumed that the laser beam is moved along the closed contour, along with a stepwise change in the distance between the lens and the metal-ceramic substrate, which is made after each crossing of the closed contour or after a certain constant number of crossings.

[0027] Preferably, the metal-ceramic substrate comprises one or more back-side metallizations. In particular, one or more back-side metallizations and one or more metallizations are arranged on both sides of the ceramic element. By forming recesses that extend to and ablate the back-side metallizations, it is advantageously possible to create burr-free recesses in the back-side metallizations, particularly on the side of the back-side metallizations facing away from the ceramic layer. Thus, the method differs from conventional methods, particularly those using, for example, a CO2 laser, in that a final post-processing step of deburring the recesses is omitted. This accelerates the manufacturing process to produce the metal-ceramic substrates in which the recesses are provided.

[0028] Preferably, the laser beam is guided along a curved contour, at least partially, to form a recess. In particular, the curved contour corresponds to the direction of motion along which the laser beam is guided, resulting in a path that is at least partially annular or circular around the edge of the recess. Alternatively, a polygonal or angular or linear edge contour of the recess is conceivable, achieved by corresponding adjustment of the direction of motion of the laser beam (particularly by mirror alignment).

[0029] Furthermore, preferably, the separated components of the metal-ceramic substrate are removed, preferably by a vacuum mechanism. For example, a suction device is provided for this purpose, preferably integrated with the carrier and positioned beneath the area intended for the processing area or recess. As the laser beam follows the corresponding contour which will become the boundary of the later recess, the area of ​​the metal-ceramic substrate enclosed by the boundary or later boundary is cut. It is advantageously possible to fix the remaining or separated portion of the metal-ceramic substrate to the carrier by a vacuum mechanism, while the metal-ceramic substrate remains free from the carrier, in order to enable or facilitate the separation of the cut region of the metal-ceramic substrate from the remaining metal-ceramic substrate having the manufactured recess.

[0030] A further aspect of the present invention is an apparatus for performing the processing according to the present invention. All features and advantages described in the method apply to the apparatus, and all features and advantages described in the apparatus apply to the method.

[0031] A further aspect of the present invention is a metal-ceramic substrate manufactured by the process according to the present invention. All properties and advantages described in the method can be similarly applied to the metal-ceramic substrate, and all properties and advantages described in the metal-ceramic substrate can be similarly applied to the method.

[0032] Further advantages and features can be derived from the following description of preferred embodiments of the subject matter according to the present invention, with reference to the accompanying drawings. The individual features of each embodiment can thereby be combined with one another within the scope of the present invention. [Brief explanation of the drawing]

[0033] [Figure 1] A schematic diagram of a method for processing a metal-ceramic substrate according to a first exemplary embodiment of the present invention. [Figure 2]A schematic diagram of a method for processing a metal-ceramic substrate according to a second exemplary embodiment of the present invention. [Figure 3] A schematic diagram of a method for processing a metal-ceramic substrate according to a third exemplary embodiment of the present invention. [Figure 4] A schematic diagram of a method for processing a metal-ceramic substrate according to a fourth exemplary embodiment of the present invention. [Modes for carrying out the invention]

[0034] Figure 1 schematically illustrates a method for processing a metal-ceramic substrate 1 according to a first preferred embodiment of the present invention. Such a metal-ceramic substrate 1 preferably functions as a carrier element for an electronic or electrical component that can be connected to the metal-ceramic substrate 1 in each case. Essential components of such a metal-ceramic substrate 1 are a ceramic element 11 extending along the main surface HSE and one or more metal layers 21 bonded to the ceramic element 11. The ceramic element 11 is made from one or more materials including ceramic. In this case, the one or more metal layers 21 and the ceramic element 11 are arranged vertically along a stacking direction extending perpendicular to the main surface HSE and, in the manufactured state, are substantially bonded to each other in at least one area via bonding surfaces. The ceramic element 11 may also be made from a plurality of ceramic layers comprising one or more ceramic layers, for example, with intermediate metallization or hybrid ceramics formed between them. Preferably, one or more metal layers 21 are then patterned to form conductor paths or connection points for electrical components. For example, this structuring is etching of one or more metal layers 21. However, it is necessary to first form a permanent bond (particularly a material bond) between one or more metal layers 21 and the ceramic element 11.

[0035] A system for manufacturing a metal-ceramic substrate 1 (particularly a DCB or DAB bonding process) to permanently bond one or more metal layers 21 to a ceramic element 11 comprises a furnace in which the laminated assembly of the ceramic element 11 and the one or more metal layers 21 is heated to achieve bonding. For example, the one or more metal layers 21 are copper metal layers, and the one or more metal layers 21 and the ceramic element 11 are bonded together using a DCB (direct copper bonding) bonding method. Alternatively, the one or more metal layers 21 can be bonded to the ceramic element 11 by an active soldering method or a thick-film method.

[0036] After bonding (particularly by DCB treatment, active soldering treatment and / or thick film treatment), the metal-ceramic substrate is provided as a large card. Such large cards are singulated in subsequent processing to provide singulated metal-ceramic substrates 1 in each case. Preferably, for such separation, the large card is intended to be processed by laser light 10 (particularly by ultrashort pulse laser light). This makes it possible to immediately achieve separation by laser light 10 and / or form a predetermined fracture line. Along that fracture line, the large card is fractured in subsequent processing to form the separated metal-ceramic substrate 1. By ultrashort pulse laser, those skilled in the art will understand such laser sources that emit laser pulses with a pulse length of less than 1 nanosecond, in particular. Preferably, the pulse duration is between 0.1 and 100 ps. Furthermore, it is assumed that the pulse duration is in the femtosecond range (i.e., 0.1 to 100 fs). In the exemplary embodiment shown in Figure 1, the metal-ceramic substrate 1 is placed on a carrier 40.

[0037] In particular, a laser beam 10 (especially the laser beam 10 of a UKP laser) is used to generate a recess 15 (especially a through recess 15) in the metal-ceramic substrate 1. The recess 15 is, for example, a type of through-hole used for through-plating, and / or a recess 15 provided as a through-hole to provide a connection or fixing area to which the metal-ceramic substrate 1 is coupled to a housing or another component as a power module. In this case, the recess 15 is generated temporarily before and after a predetermined break line. Preferably, the same laser beam 10 (i.e., light from the same laser source) is used to generate the recess 15 and the predetermined break line. The pulse intensity, pulse duration and / or power for generating the predetermined break line are different from those for generating the recess 15.

[0038] Furthermore, conveniently, the metallic ceramic substrate 1 is stationary and positioned by the carrier 40. The laser beam 10 is moved over the metallic ceramic substrate 1 to generate predetermined fracture lines and / or recesses 15 in the metallic ceramic substrate 1 (in particular, having a specific path as seen across the metallic ceramic substrate). In other words, instead of moving the metallic ceramic substrate 1 relative to the alignment position of the laser beam 10, it is expected that the alignment position of the laser beam 10 is performed in such a manner that the laser beam 10 traversing the metallic ceramic substrate 1 generates predetermined fracture lines and / or recesses 15 at their respective collision points. It is assumed that the predetermined fracture lines and / or recesses 15 are continuous and / or discontinuous, i.e., the predetermined fracture lines appear as perforations.

[0039] In particular, the laser beam 10 is directed toward a mirror element 30 to align the laser beam 10 to a specific processing area or area on the metal-ceramic substrate 1. The laser beam 10 is reflected by the mirror element 30 and subsequently strikes the metal-ceramic substrate 1. In this case, the mirror element 30 is pivotably mounted, particularly pivotally with respect to two or more axes, to align the laser beam 10 to a specific processing area or area on the metal-ceramic substrate. Furthermore, preferably, a lens 20 is positioned between the mirror element 30 and the metal-ceramic substrate 1. In particular, the lens 20 extends in a plane substantially perpendicular to the incident direction of the laser beam 10, over a length substantially corresponding to the length and / or width of the metal-ceramic substrate 1, particularly as a large card. In other words, the laser beam 10 traveling across the metal-ceramic substrate 1 always passes through the same lens 20 regardless of the processing area.

[0040] It has been shown to be particularly advantageous to use a lens 20 with a focal length exceeding 300 mm, preferably exceeding 350 mm, and more preferably exceeding 420 mm. Placing the lens 20 at a distance A from the metal-ceramic substrate 1, which essentially corresponds to the focal length of the lens 20, makes it possible to generate a predetermined fracture point or predetermined fracture line or recess 15 that is relatively slightly inclined with respect to the perpendicularity of the main surface HSE of the metal-ceramic substrate 1. Otherwise, an angle of inclination of the predetermined fracture line or recess 15, which is essentially V-shaped or notched, would have to be expected. This applies in particular to predetermined fracture lines or recesses 15 that form the edges of the metal-ceramic substrate 1. Such inclined portions arise, in particular, from the fact that the laser light 10 or laser beam cannot strike the metal-ceramic substrate 1 uniformly and perpendicularly across the entire metal-ceramic substrate 1. However, by using a focal length exceeding 300 mm, this inclination (particularly in the edge region of the metal-ceramic substrate 1) is reduced so that the angle of inclination measured or referenced with respect to the perpendicularity of the metal-ceramic substrate 1 is less than 10°, more preferably less than 10°. In particular, it is established that the deviation of the inclination angle compared to the orientation of a predetermined fracture line at the center of the metal-ceramic substrate 1 does not fall below 12°. Therefore, it is advantageously possible to produce a substantially homogeneous distribution of these fracture behaviors throughout the entire metal-ceramic substrate 1.

[0041] Furthermore, preferably, the distance A between the lens 20 and the upper surface OS of the metal-ceramic substrate 1 changes, particularly decreases, during the process for manufacturing the recesses 15. Therefore, it is advantageously possible to track the focus of the laser beam 10 produced by the lens 20 according to the depth of the recesses 15 already fabricated during the processing of the metal-ceramic substrate 1. In other words, as the ablation of one or more metal layers 21 and / or ceramic elements 11 increases, it is possible to consider continuous ablation for forming the recesses 15 by varying the distance A such that the focus of the laser beam 10 shifts towards the metal-ceramic substrate 1 and / or to the back side of the metal-ceramic substrate. Thus, the laser power is kept as high as possible in the area of ​​material currently being ablated. As a result, the decrease in laser efficiency for material ablation is not expected with increasing ablation depth. This is advantageously an accelerated ablation process that accelerates the formation of the recesses 15. In particular, by varying the distance A, a shift in focus along the stacking direction S occurs, where the distance A between the lens 20 and the upper surface OS of the metal-ceramic substrate 1 preferably changes continuously and / or sequentially or stepwise. To change the distance A, the lens 20 is preferably displaced along a direction perpendicular to the main surface HSE. Alternatively and / or in addition to this, it is assumed that the carrier 40 and therefore the metal-ceramic substrate 1 are displaced along a direction extending parallel to the stacking direction S so as to decrease the distance A between the lens 20 and the upper surface OS of the metal-ceramic substrate 1. In particular, the focal length of the lens 20 is constant.

[0042] Figure 2 schematically illustrates a method for producing a metal-ceramic substrate 1 according to a second exemplary embodiment of the present invention. The method shown in Figure 2 differs from the exemplary embodiment shown in Figure 1 in that a suction device 25 is additionally provided. The suction device 25 is, for example, integrated with a carrier 40 and positioned beneath the processing area where the planned recess 15 is realized. The suction device 25 can advantageously generate negative pressure to suck in ablated particles of the metal-ceramic substrate 1 and / or ensure that partial areas of the metal-ceramic substrate 1 separated during processing and / or during the formation of the recess 15 can be separated from the metal-ceramic substrate 1 by the recess 15. In particular, this relates to processing for forming a recess 15 in which the cross-section in the direction parallel to the main plane HSE is much larger than the cross-section of the laser beam 10. In such scenarios, where the diameter and / or cross-section of the laser beam 10 is smaller than the cross-section of the recess 15, the laser beam 10 follows movement along the processing direction B during processing, for example, forming the contour of the recess 15 in a plane parallel to the main plane HSE. The portion of the metal-ceramic substrate 1 enclosed by its contour is then secured to the carrier 40 by a vacuum mechanism as part of the remaining components. Meanwhile, the remaining terminated portion of the metal-ceramic substrate 1 is released from the carrier 40.

[0043] Figure 3 schematically illustrates a method for generating a recess 15 in a metal-ceramic substrate 1 according to a third exemplary embodiment of the present invention. In particular, Figure 3 shows a top view of the metal-ceramic substrate 1 and the movement of a laser beam 10 along a movement direction B, forming an annular or arc-shaped contour. It is also conceivable that the laser beam 10 follows a helical contour, in particular having a decreasing and / or increasing radius. In particular, an annular contour for the recess 15 is intended to be realized by a correspondingly selected processing direction B, where the recess 15 has a first diameter D1 and the laser beam 10 has a second diameter D2 in a plane extending parallel to the principal plane HSE. In this case, the ratio of the second diameter D2 to the first diameter D1 is less than 0.2, preferably less than 0.1, and more preferably less than 0.05. As an alternative to the annular movement direction B, a polygonal movement direction B, a polygonal movement direction B and / or at least partially linear movement direction B are also conceivable.

[0044] Figure 4 schematically illustrates a method for processing a metal-ceramic substrate 1 according to a fourth preferred embodiment of the present invention. In particular, Figure 4 shows a cross-sectional view through the metal-ceramic substrate 1 along a cross section perpendicular to the main surface HSE. In this case, in particular, during processing with the laser beam 10 (particularly for generating through-holes or through-recesses 15), backside metallization 30 is also removed by the laser beam 10 (particularly the laser beam 10 from an ultrashort pulse laser). By using an ultrashort pulse laser, when generating recesses 15, it is advantageously possible to avoid the formation of burrs, for example, which are typically formed during manufacturing using a CO2 laser. Correspondingly, a post-processing step for deburring the formed burrs can therefore be avoided. This represents a time advantage for fabricating a metal-ceramic substrate 10 having recesses 15. In particular, the recesses 15 are provided to receive fastening elements, such as receiving bolts and / or screws extending through the recesses 15 to fix the metal-ceramic substrate 1, for example, to a housing or another component. [Explanation of Symbols]

[0045] 1. Metal-ceramic substrate 10 Laser light 11 Ceramic elements 15 recesses 20 lenses 21 Metal layer 25 Suction devices 30. Backside metallization OS top HSE Main Surface S stacking direction S Processing direction D1 First diameter D2, the second diameter

Claims

1. A method for processing and fixing a metal-ceramic substrate (1), A step of providing a metal-ceramic substrate (1), wherein the metal-ceramic substrate (1) comprises one or more metal layers (21) and one ceramic element (11), which are arranged vertically along a stacking direction (S) that extends along a main surface (HSE) and perpendicular to the main surface (HSE). The process includes the step of forming through recesses (15) in the metal-ceramic substrate (1) by processing with an ultrashort pulse laser, and using the through recesses (15) as areas in which a fixing element engages to fix the metal-ceramic substrate (1) to a housing or another component, The cross-section of the through recess (15) extending parallel to the main surface (HSE) has a first diameter, the cross-section of the ultrashort pulse laser measured along the same plane has a second diameter, and the ratio of the second diameter to the first diameter is less than 0.

2. The method wherein the processing with the ultrashort pulse laser is performed only in areas of the metal-ceramic substrate (1) that do not contain metal.

2. The method according to claim 1, wherein the ultrashort pulse laser is directed to a processing area of ​​the metal-ceramic substrate (1) via a lens (20), and the distance (A) between the lens (20) and the upper surface (OS) of the metal-ceramic substrate (1) changes during processing.

3. The method according to claim 2, wherein the focal length (L) of the lens exceeds 300 mm.

4. The method according to claim 3, wherein the distance (A) changes continuously or in steps.

5. The method according to any one of claims 1 to 4, wherein the metal ceramic substrate (1) comprises one or more backside metallizations (30).

6. The method according to any one of claims 1 to 5, wherein the ultrashort pulse laser is guided at least partially along a curved contour to form the through recess (15).

7. The method according to any one of claims 1 to 6, wherein the separated components of the metal ceramic substrate (1) are removed by a vacuum mechanism.

8. The method according to any one of claims 1 to 7, wherein the through recess (15) is generated by repeatedly traversing the metal ceramic substrate (1) along the same contour with the ultrashort pulse laser.

9. The method according to any one of claims 1 to 8, wherein the ultrashort pulse laser is incident perpendicularly on the upper surface of the metal ceramic substrate (1) during processing.

10. The method according to any one of claims 1 to 9, wherein further laser light is provided and the through recess (15) is formed by the ultrashort pulse laser and the further laser light.

11. The method according to any one of claims 1 to 10, wherein the ceramic element of the metal ceramic substrate (1) does not contain glass.

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