Method for producing a base substrate and such a base substrate

Abstract

Method for producing a base substrate (1) comprising at least one ceramic layer (3) which is provided with at least one metallization (4, 5) on at least one surface side (3.1, 3.2), in which the metallization (4, 5) is structured to produce a plurality of individual metal-ceramic substrates (2) from the base substrate (1), and in which, in order to separate unused edge regions (1a-1d) of the base substrate (1) and / or to separate the plate-like base substrate (1) into the individual metal-ceramic substrates (2), a plurality of predetermined breaking lines (6a-6f) are introduced into at least one surface side (3.1, 3.2) of the ceramic layer (3) of the base substrate (1) by means of a laser device, wherein the predetermined breaking lines (6a-6f) are generated by means of ultrashort pulse or short pulse second lasers.

Description

The invention relates to a base substrate according to the preamble of claim 10 and to a method for manufacturing a base substrate according to the preamble of claim 1.Substrates, in particular base substrates in the form of printed circuit boards consisting of a ceramic layer and at least one metallization which is connected to a surface side of the ceramic layer and can be structured to form conductor tracks, contacts, contact areas or connection areas, are known in a wide variety of designs. By appropriate structuring of the metallization, it is possible in particular to produce a plurality of metal-ceramic substrates on the base substrate and then to individualize these in the course of the production method. The metal-ceramic substrates obtained thereby are used, for example, for the construction of power semiconductor modules.For connecting metal foils or metal layers forming the metallization to one another or to a ceramic substrate or a ceramic layer, the so-called "DCB method" ("direct copper bonding") is also known. In this case, metal layers, preferably copper layers or foils, are joined to one another and / or to a ceramic layer, specifically using metal or copper sheets or metal or copper foils which have on their surface sides a layer or a coating ("melting layer") of a chemical compound of the metal and a reactive gas, preferably oxygen. In this method described, for example, in U.S. Pat. No. 3,744,120 A or in DE 23 19 854 A, this layer or this coating ("melting layer") forms a eutectic having a melting temperature below the melting temperature of the metal (e.g. copper), so that, by placing the metal or copper foil on the ceramic layer and by heating all the layers, these can be connected to one another, namely by melting the metal layer or copper layer substantially only in the region of the melting layer or oxide layer. Such a DCB method then has, for example, the following method steps:oxidizing a copper foil to form a uniform copper oxide layer;applying the copper foil with the uniform copper oxide layer to the ceramic layer;heating the composite to a process temperature of between about 1025 and 1083° C., for example to about 1071° C.;Cool to room temperature.Furthermore, the so-called active solder method for connecting metal layers or metal foils forming metallizations, in particular also copper layers or copper foils, to a ceramic material or a ceramic layer is known from the publications DE 22 13 115 A and EP 0 153 618 A2. In this method, which is also used specifically for producing metal-ceramic substrates, a connection between a metal foil, for example copper foil, and a ceramic substrate, for example an aluminum nitride ceramic, is produced at a temperature of between approximately 800-1000° C. using a hard solder which, 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 of the group Hf, Ti, Zr, Nb, Ce, establishes a connection between the hard solder and the ceramic by a chemical reaction, while the connection between the hard solder and the metal is a metallic hard solder connection.Methods for the flat connection of an aluminum layer to a ceramic layer are also known under the designation "direct aluminum bonding" ("DAB method"). In principle, adhesive bonds or adhesive techniques using plastic adhesives, for example using epoxy-resin-based adhesives, can also be used for such bonding of two layers, and in particular also fiber-reinforced adhesives. It is also known in particular to use special adhesives which contain carbon fibers and / or carbon nanofibers and / or carbon nanotubes, and / or adhesives with which a thermal and / or electrically highly conductive adhesive bond is possible. Said connection technologies can of course also be used in combination if a plurality of metal layers are provided both on the bottom side and on the top side of the ceramic layer.To produce the metal-ceramic substrates, at least one of the metallization of the base substrate is structured accordingly and predetermined breaking points or predetermined breaking lines are introduced at least along the free edge sections of the base substrate into the ceramic surface freed of metal, along which breaking points or predetermined breaking lines at least the unused edge sections of the base substrate are preferably removed manually. Even when a plurality of individual metal-ceramic substrates are produced from the base substrate in multiple use, the metal-ceramic substrates produced on the base substrate, for example a large substrate plate, are divided by a plurality of predetermined breaking lines running parallel and perpendicular to one another into a plurality of preferably rectangular or square individual substrates and are separated by appropriate breaking of the base substrate along the predetermined breaking lines introduced into the ceramic layer.Various methods are known for generating such predetermined fracture lines. Laser devices are often used for this purpose, by means of which a plurality of recesses of the same depth are introduced into the ceramic surface in order to produce a predetermined breaking line, namely by application of a correspondingly modulated or pulsed laser beam. The recesses can be arranged, for example, spaced apart from one another along a line or overlap one another.EP 2 315 508 A1 also discloses, in particular, a method for producing individual ceramic substrates from a base substrate in multiple use, in which continuous slot-like predetermined breaking lines are introduced into an upper side of the base substrate by means of a laser device. In order to avoid undesired breaking of the base substrate at the introduced continuous slot-like break lines during the manufacturing method, the break lines have the smallest depth in the region of the free, unused edge sections of the base substrate. The material thickness of the remaining ceramic layer is thus greatest at the edge in the slot-like predetermined breaking lines, whereby an undesired breaking of the base substrate during the production process is to be prevented.US 2009 / 0 242 525 A1 discloses the engraving of ceramics with laser light and US 2007 / 0 072 395 A1 discloses the production of scribe structures having different depths during the production of predetermined fracture lines.However, disadvantageously, in the case of ceramic substrates having such predetermined breaking lines, when the edge sections are manually removed or the individual substrates are separated, breaks, possibly even schollene fractures, occur in the ceramic layer, in particular in the crossing regions of the predetermined breaking lines, which lead to considerable damage and thus to unusableness of the separated substrate. A reduction in the waste rate caused by this in known production methods is therefore of particular economic importance.Proceeding from the aforementioned prior art, the object of the invention is to show a base substrate, a metal-ceramic substrate produced therefrom and a method suitable for producing the same, which enables reliable manual removal of the unused edge sections of the base substrate and reliable separation of the base substrate into individual metal-ceramic substrates without damage to the respective metal-ceramic substrate, whereby the marked reduction of the waste rate is achieved.The object is achieved by a method according to claim 1 and a base substrate according to claim 10.The preferred aspect of the base substrate is that the break-off lines have a first depth at least in the crossing regions and a second depth outside the crossing regions, wherein the first depth is greater than the second depth. Particularly advantageously, a lower breaking force is thus required in the corner regions of the metal-ceramic substrates to be separated, as a result of which in particular the occurrence of wild fractures, in particular also schollate fractures, can be effectively prevented and the waste rate of the separating process can thus be significantly reduced. Furthermore, the stress present in the base substrate is advantageously reduced, in particular in the crossing regions, and the generation of microcracks is minimized. The singulated metal-ceramic substrate also has a high quality edge line.In an advantageous development of the invention, the predetermined fracture lines are introduced in a first surface side of the ceramic layer and / or in the opposite second surface side of the ceramic layer. The predetermined breaking lines can also be provided, for example, on the surface side of the ceramic layer opposite the structured metallization, so that the base substrate can already be equipped with electronic components before the individual metal-ceramic substrates are separated.Furthermore, the predetermined breaking lines can advantageously be formed in the form of a continuous depression or in the form of a discontinuous depression, wherein the continuous depressions are preferably formed in the manner of slits and the discontinuous depressions are formed by a linear arrangement of a plurality of weft craters in a surface side which are arranged, for example, at a distance from one another and / or overlapping. In the case of the configuration in the form of continuous slot-like depressions or so-called "grooves", a reduction in the width of the depressions to up to one third in comparison with the injection craters and thus also a small amount of material removed is achieved. In addition, an improved notch effect is advantageously also obtained and the introduction of cracks can be controlled significantly better. In addition, significantly less fracture dust and few fragments are produced during the separation of the metal-ceramic substrates in comparison with predetermined fracture lines formed by shot craters.According to a further advantageous embodiment of the invention, the increased first depth of the predetermined fracture lines provided in the crossing regions is produced by subjecting the crossing regions to a laser beam generated by the laser device multiple times with homogeneous power or by subjecting the crossing regions once to a laser beam generated by the laser device with controllable power. Depending on the laser device used in each case, the predetermined fracture lines of different depths can be generated quickly and easily in a simple or multiple process step to be carried out.Advantageously, the predetermined breaking lines in the crossing regions have a first depth which is greater by 20% to 80% compared to the second depth, wherein the second depth is preferably between 30 μm and 200 μm and / or the first depth is less than 80% of the material thickness of the ceramic layer. The first depth of the predetermined breaking lines preferably extends over a length of 0.2 mm to 20 mm in the crossing regions.The invention likewise relates to a metal-ceramic substrate produced from a partial region of the ceramic layer of the base substrate delimited by at least four of the predetermined breaking lines, having at least one patterned metallization section provided on the surface side of the ceramic layer.The present invention furthermore relates to a method for producing a base substrate comprising at least one ceramic layer which is provided on at least one surface side with at least one metallization, in which the metallization is structured to produce a plurality of individual metal-ceramic substrates from the base substrate, and in which a plurality of predetermined fracture lines are introduced into at least one surface side of the ceramic layer of the base substrate for separating unused edge regions of the base substrate and / or for singulating the plate-like base substrate into the individual metal-ceramic substrates by means of a laser device. In this case, it is preferably provided that in each case two of the predetermined breaking lines intersect in in each case one intersecting region. Particularly advantageously, the predetermined fracture lines are introduced into the ceramic layer by means of the laser device in such a way that they have a first depth at least in predetermined crossing regions and a second depth outside the crossing regions, wherein the first depth is greater than the second depth. The method according to the invention can be implemented quickly and easily and significantly reduces the waste which arises during the separation of the metal-ceramic substrates.According to a development of the method according to the invention, at least one of the metallizations is structured before the introduction of the predetermined breaking lines and subsequently the predetermined breaking lines are introduced into the first surface side of the ceramic layer and / or the opposite second surface side of the ceramic layer.Advantageously, the predetermined breaking lines can be introduced into the ceramic layer in the form of a continuous or discontinuous predetermined breaking lines, wherein the continuous predetermined breaking lines are formed in the form of slot-like depressions and the discontinuous predetermined breaking lines are formed by a line-like arrangement of a plurality of shot craters in the surface side of the ceramic layer. For this purpose, the increased first depth of the predetermined fracture lines provided in the crossing regions is generated either by subjecting the crossing regions to a laser beam generated by the laser device a plurality of times with homogeneous power or by subjecting the crossing regions once to a laser beam generated by the laser device with controllable power. The laser device with adjustable laser power is, according to the invention, an ultra-short pulse or short pulse second laser. Alternatively, a CO 2- laser device can be used to generate the discontinuous break-off lines.The predetermined fracture lines are preferably introduced by means of the laser device in an oxygen-containing atmosphere, which preferably has an oxygen content of at least 30%.The terms "approximately", "substantially", "about" or "about" mean, for the purposes of the invention, deviations from the exact value in each case by + / -10%, preferably by + / -5%, and / or deviations in the form of changes which are insignificant for the function.Developments, advantages and possible applications of the invention also result from the following description of exemplary embodiments and from the figures. All features described and / or graphically depicted are fundamentally the subject matter of the invention, either alone or in any combination, independently of their summary in the claims or their reference back. The contents of the claims are also made part of the description.The invention is explained in more detail below on the basis of the figures using exemplary embodiments. The following are shown: FIG. 1 shows a simplified sectional illustration through a base substrate for producing a plurality of metal-ceramic substrates in the multiple panel, FIG. 2 shows a simplified plan view of the base substrate according to FIG. 1, FIG. 3 shows a simplified sectional illustration through a first embodiment variant of a predetermined breaking line in the ceramic layer, FIG. 4 shows a simplified sectional illustration through the predetermined breaking line according to FIG. 3 in the crossing region, FIG. 5 shows a simplified sectional illustration through a second embodiment variant of a predetermined breaking line in the ceramic layer, FIG. 6 shows a simplified sectional illustration through the predetermined breaking line according to FIG. 5 in the crossing region, FIG. 7 is a detail illustration of a plan view of the crossing region of two predetermined breaking lines in the corner region of a base substrate, and FIG. 8 shows a section A-A along a predetermined breaking line through the base substrate according to FIG. 7.FIG. 1 shows, by way of example, in a simplified illustration, a section through a base substrate 1 for producing metal-ceramic substrates 2 in multiple use.The base substrate 1 comprises in each case at least one ceramic layer 3 having two opposite surface sides, namely a first and second surface side 3.1, 3.2. At least one of the surface sides 3.1 is provided with a metallization 4 in the base substrate 1. Preferably, a further metallization 5 is provided on the respective opposite surface side 3.2.In the present exemplary embodiment, the first surface side 3.1 has a first metallization 4 and the second surface side 3.2 has a second metallization 5, wherein the first metallization 4 is structured to form contact surfaces and / or conductor tracks and / or further fastening regions of metal-ceramic substrates 2, specifically in such a way that a plurality of self-contained structuring regions are produced which are assigned to a metal-ceramic substrate 2.In particular, the first metallization 4 in the edge sections 1 a- 1 d,which cannot be used for producing the metal-ceramic substrates 2 and are therefore unused, is removed at least in sections, so that the first surface side 3.1 of the ceramic layer 3 is exposed in these sections. Furthermore, for production in multiple use, the metallizations 4, 5 are also removed in the transition regions between two regions of the metallizations 4, 5 which are structured next to one another on the base substrate 1 in order to form a metal-ceramic substrate. At least in these regions, a plurality of predetermined fracture lines 6 a- 6 fare introduced in a manner known per se by means of a laser device, not shown in the figures, namely a laser beam generated by the laser device. The predetermined breaking lines 6 ato 6 fare used here for preferably manually breaking the base substrate 1 along the predetermined breaking lines 6 ato 6 f.In the present exemplary embodiment, the first metallization 4 is formed or produced by a foil or layer of copper or a copper alloy and is applied directly to the ceramic layer 3. In one embodiment variant of the invention, the second surface side 3.2 opposite the first surface side 3.1 is provided with the second metallization 5, which is preferably also formed or produced by a foil or layer of copper or a copper alloy. The first and second metallization 4, 5 can also be produced from aluminum, an aluminum alloy, steel or a steel alloy.The first and second metallizations 4, 5 made of copper or a copper alloy are preferably directly connected in a planar manner to the first and second surface sides 3.1, 3.2 of the ceramic layer 3 using the DCB method described at the beginning. Alternatively, a connection can also be provided by adhesive bonding using a plastic adhesive or a polymer suitable as an adhesive, preferably using an adhesive containing carbon fibers, in particular carbon nanofibers, to the first or second surface side 3.1, 3.2 of the ceramic layer 3. Alternatively or in combination, the active solder method described at the beginning can be used.If metallizations 4, 5 are realized in the form of a layer of aluminum or an aluminum alloy, a "direct aluminum bonding" method can be used. The first metallization 4, for example made of copper or a copper alloy, has a layer thickness between 0.1 mm and 1.0 mm, for example. The layer thickness of the second metallization 5 can be designed accordingly. In the case of aluminum, the layer thickness is, for example, between 0.1 mm and 5.0 mm, preferably between 0.3 mm and 3.0 mm.Alternatively, at least one of the metallizations 4, 5 can be produced from copper, silver and / or gold using thick-film technology, and specifically preferably with a film thickness of 15 μm to 100 μm. The layers are preferably produced at a process temperature of 500° C. to 1200° C.The ceramic layer 3 is made, for example, of an oxide, nitride or carbide ceramic such as aluminum oxide (Al2O3) or aluminum nitride (AlN) or silicon nitride (Si3N4) or silicon carbide (SiC) or of aluminum oxide with zirconium oxide (Al2O3+ZrO2) and has a layer thickness, for example, between 0.25 mm and 1.0 mm, preferably between 0.2 mm and 0.7 mm.FIG. 2 shows a plan view of the first surface side 3.1 of the base substrate 1 according to the invention as per FIG. 1. in this embodiment variant, a plurality of metal-ceramic substrates 2 are produced from the base substrate 1 in multiple use, namely for example four metal-ceramic substrates 2. to this end, in a first step, the unused edge sections 1 a, 1 b, 1 c, 1 dof the base substrate 1 are to be removed, namely by breaking along the predetermined breaking lines 6 ato 6 dapplied to the first surface side 3.1 of the ceramic layer 3. The predetermined breaking lines 6 ato 6 drun parallel in pairs and perpendicular to one another in pairs for this purpose and cross in four crossing regions K 1 to K 4 of the base substrate 1, which are preferably located in the corner regions of the base substrate 1. The introduced predetermined breaking lines 6 ato 6 dtherefore form a preferably rectangular and closed frame enclosing the region of the base substrate 1 provided for producing the metal-ceramic substrates 2.In the present embodiment, first to fourth break lines 6 ato 6 dare provided, the first break line 6 aseparates the first unused edge portion 1 a, the second break line 6 bseparates the second unused edge portion 1 b, the third break line 6 cseparates the third unused edge portion 1 c, and the fourth break line 6 dseparates the fourth unused edge portion 1 dfrom the metal-ceramic substrates 2 provided on the base substrate 1, respectively. In this case, the first and second predetermined breaking lines 6 a, 6 band the third and fourth predetermined breaking lines 6 c, 6 drun in each case parallel to one another. Accordingly, the first predetermined breaking line 6a intersects the fourth predetermined breaking line 6d in the first crossing region K1 and the third predetermined breaking line 6c in the second crossing region K2, and the second predetermined breaking line 6b intersects the fourth predetermined breaking line 6d in the third crossing region K3 and the third predetermined breaking line 6c in the fourth crossing region K4. When the edge sections 1 ato 1 dof the base substrate 1 are manually removed, fractures, in particular also schollate fractures, can occur in the crossing regions K 1 to K 4, as a result of which the respective metal-ceramic substrate 2 becomes unusable.According to the invention, slot-like predetermined breaking lines 6 a- 6 dare introduced into the ceramic layer 3 by means of the laser device in such a way that they have a first depth T 1 at least in the crossing regions K 1 to K 4 and a second depth T 2 outside the crossing regions K 1 to K 4, wherein the first depth T 1 is greater than the second depth T 2. The first depth T 1 is preferably 20% to 80% greater than the second depth T 2, which is preferably between 30 μm and 200 μm. The first depth T 1 is preferably less than 80% of the material thickness of the ceramic layer 3, i.e. the first depth T 1 does not exceed 20% of the material thickness of the ceramic layer 3.The predetermined breaking lines 6 a- 6 dhave the first depth T 1 in the respective intersection region K 1 to K 4 preferably over a length L of 0.2 mm to 20 mm, wherein this is preferably arranged symmetrically with respect to the intersection point P 1 to P 4 of the slot-like predetermined breaking lines 6 a- 6 d, i.e. the first depth T 1 extends from the intersection point P in each case over a partial length TL of 0.1 mm to 10 mmFor production in multiple use, the base substrate 1 has further predetermined breaking lines 6 e- 6 hwhich subdivide the region of the base substrate 1 enclosed by the first to fourth predetermined breaking lines 6 ato 6 dinto a plurality of subareas for producing the individual metal-ceramic substrates 2. In the present exemplary embodiment, a fifth and sixth predetermined breaking line 6 e, 6 fare provided, wherein the fifth predetermined breaking line 6 eextends parallel to the first and second predetermined breaking lines 6 a, 6 band perpendicular to the third and fourth predetermined breaking lines 6 c, 6 d. The sixth predetermined breaking line 6 fextends parallel to the third and fourth predetermined breaking lines 6 c, 6 dand perpendicular to the first and second predetermined breaking lines 6 a, 6 b.This results in further intersection regions K 5 to K 9, in which, in a preferred embodiment variant of the invention, the first depth T 1 of the predetermined breaking lines 6 a- 6 fis likewise increased compared to the line sections located outside the intersection regions K 5 to K 9 compared to the second depth T 2.In detail, in the present exemplary embodiment, a fifth intersection region K 5 is obtained between the first and sixth predetermined fracture lines 6 a, 6 f, a sixth intersection region K 6 is obtained between the third and fifth predetermined fracture lines 6 c, 6 e, a seventh intersection region K 7 is obtained between the second and sixth predetermined fracture lines 6 b, 6 f, an eighth intersection region K 8 is obtained between the fourth and fifth predetermined fracture lines 6 d, 6 eand a ninth intersection region K 9 is obtained between the fifth and sixth predetermined fracture lines 6 e, 6 f. The free end portions of the fifth and sixth predetermined breaking lines 6 e, 6 fhere preferably extend beyond the crossing region K 5 to K 8 into the respective unused edge portions 1 ato 1 d, namely preferably between 300 μm and 700 μm, preferably approximately 500 μm.The configuration of the cross-sectional shape of the predetermined breaking lines 6 a- 6 fand / or of the respective depth T 1, T 2 is dependent here on the laser device used for the introduction.In a first embodiment variant of the invention, the laser device can be formed by a laser device with controllable laser power, by means of which the material removal in the ceramic layer 3 produced by the laser beam and thus the depth T 1, T 2 of the slot-like predetermined breaking lines 6 a- 6 fcan be controlled in sections. Laser devices of this type can be designed as solid-state lasers with different pulse durations, according to the invention as an ultra-short pulse or short pulse second laser, preferably in the 100 watt range or the HC range. The latter solid-state lasers can be formed, for example, in the form of a nanosecond laser having, for example, a wavelength of 1064 nm or a picosecond laser having, for example, a wavelength of 1090 nm to 1064 nm. The laser devices mentioned thus operate, for example, in the UV range, infrared range or in a green spectral range. FIGS. 3 and 4 each show a cross section through a predetermined breaking line 6 agenerated with such a laser device, specifically FIG. 3 with a second depth T 2 and FIG. 4 with a first depth T 1.The laser beam generated by the laser device is applied to the respective surface side 3.1, 3.2 of the ceramic layer 3, which is optionally deflected by a corresponding optical device, preferably takes place perpendicular to the respective surface side 3.1, 3.2 of the ceramic layer 3.Alternatively, an arrangement of the base substrates 1 on a preferably displaceable "x-y table" arrangement is possible, to which a preferably likewise displaceable deflection optics is assigned, which is acted upon by the laser beam generated by the laser device. This also allows, inter alia, "on-the-fly" processing of the base substrates 1 and / or segment-related processing ("stitching").By means of said laser devices, slot-like predetermined fracture lines 6 a- 6 dforming continuous depressions can be introduced into the ceramic layer 3, to be precise without this resulting in a shot cone or melt ejection. To form the different depths T 1 and T 2, the laser device outputs a higher power when crossing the crossing regions K 1 to K 4 than outside the crossing regions K 1 to K 4, so that a greater removal of material thereby occurs in the crossing regions K 1 to K 4, i.e. besides the depth T 1, T 2, the intended breaking lines 6 a- 6 dmay also be widened in the crossing regions K 1 to K 4. Predetermined breaking lines 6 ato 6 fgenerated in this way have, for example, a first depth T 1 of approximately 40 μm to 180 μm and a second depth T 2 of approximately 20 μm to 90 μm.In a second embodiment variant of the method according to the invention, first of all predetermined fracture lines 6 ato 6 fhaving a uniform depth, namely the second depth T 2, are produced in the base substrate 1 by means of the laser device. Subsequently, the base substrate 1 is traversed along the generated predetermined breaking lines 6 ato 6 fby means of the laser device-preferably without changing the operating parameters of the laser device-but the base substrate 1 is only impinged on with the laser beam in the predetermined crossing regions K 1 to K 9. As a result, the already existing predetermined breaking lines 6 ato 6 fare again recessed in the crossing regions K 1 to K 9, and specifically preferably until it has reached the predefined second depth T 2. For this purpose, preferably cost-effective CO2laser devices are used, by means of which discontinuous break-off lines 6 ato 6 fare produced, which are formed by a plurality of point-like injection craters, which can be arranged either at a distance from one another or in an overlapping manner. These point-like injection craters have, for example, a distance between 150 μm and 200 μm and / or a pure opening diameter between 80 μm and 110 μm. FIGS. 5 and 6 each show a cross section through such a weft crater, namely with a second depth T 1 in FIG. 5 and with a first depth T 1 in FIG. 6. In the case of discontinuous break-off lines 6 ato 6 f, the first and second depths T 1, T 2 have to be selected to be greater in comparison with continuous break-off lines 6 ato 6 f, in order to ensure a reliable breaking behavior. For example, the first depth T 1 is between 40 μm and 260 μm or up to a maximum of 80% of the material thickness of the ceramic layer 3 and the second depth T 2 is between 20 μm and 200 μm.In particular, in the crossing regions K 1 to K 4 located in the corner regions of the base substrate 1, at least one free end of the respectively crossing predetermined breaking lines 6 ato 6 dextends as far as the edge of the base substrate 1, in order to ensure a clean separation of the edge sections 1 ato 1 dfrom the base substrate 1. In one embodiment variant, the first depth T 1 can also continue from the crossing region K 1 to K 4 to the edge of the base substrate 1.FIG. 7 shows an enlarged detail of the corner region receiving the second intersection point K 2 of the plan view of the base substrate 1 shown in FIG. 2. FIG. 8 shows a section along the line A-A through the third predetermined breaking line 6 cof the base substrate 1. Preferably, in the embodiment variant shown, the first and third predetermined breaking lines 6 a, 6 cextend in each case beyond the second intersection point K 2 as far as the edge of the base substrate 1. Analogously to this, the length L of the first and sixth predetermined breaking lines 6 a, 6 f, the third and fifth predetermined breaking lines 6 c, 6 eand the fifth and sixth predetermined breaking lines 6 e, 6 fare selected in the fifth, sixth and ninth intersection regions K 5, K 6, K 9.In an alternative embodiment variant, the first depth T 1 in the crossing regions K 5 to K 9 lying within the base substrate 1 can also be reduced in comparison with the crossing regions K 1 to K 4 lying in the corner regions of the base substrate 1.The transition between the region of first depth T 1 and second depth T 2 can be formed either continuously or in a step-like manner. The transition can also have a concave, convex or linear cross-sectional profile.In order to produce a high-quality fracture line, the base substrate 1 can be heated along the predetermined fracture lines 6 ato 6 fto a process temperature which is below its melting temperature and the melting temperature of the metallization 4, 5, and a coolant jet can then be applied to the predetermined fracture lines 6 ato 6 f, in order to bring about a controlled material cut along the predetermined fracture lines 6 ato 6 fby a thermally induced mechanical stress difference. This makes it possible to reduce the depths T 1, T 2 of the break-off lines 6 ato 6 f.The generation of the predetermined fracture lines 6 ato 6 fcan also be carried out by means of the described laser devices in an oxygen-containing atmosphere which preferably has an oxygen content of at least 30%.The invention has been described above with reference to exemplary embodiments. It is understood that numerous changes and modifications are possible without thereby departing from the inventive concept underlying the invention.List of reference numbers:1 Base substrate 1 a- 1 dfirst to fourth edge portion 2 Metal-ceramic substrates 3 Ceramic layer 3.1 First surface side 3.2 Second surface side 4 First metallization 5 Second metallization 6 a- 6 ffirst to sixth break lines K 1-K 9 First to ninth crossing region L Length P Crossing point TL Part length T 1 First depth T 2 Second depth

Claims

Method for producing a base substrate (1) comprising at least one ceramic layer (3) which is provided on at least one surface side (3.1, 3.2) with at least one metallization (4, 5), in which the metallization (4, 5) is structured to produce a plurality of individual metal-ceramic substrates (2) from the base substrate (1), and in which a plurality of predetermined breaking lines (6a-6f) are introduced into at least one surface side (3.1, 3.2) of the ceramic layer (3) of the base substrate (1) in order to separate unused edge regions (1a-1d) of the base substrate (1) and / or to separate the plate-like base substrate (1) into the individual metal-ceramic substrates (2) by means of a laser device, wherein the predetermined breaking lines (6a-6f) are produced by means of ultra-short pulse or short pulse second lasers.Method according to Claim 1, wherein two of the predetermined fracture lines (6a-6f) intersect in each case in an intersecting region (K1 to K9), characterized in that the predetermined fracture lines (6a-6f) are introduced into the ceramic layer (3) by means of the laser device in such a way that they have a first depth (T1) at least in predetermined intersecting regions (K1 to K9) and a second depth (T2) outside the intersecting regions (K1 to K9), wherein the first depth (T1) is greater than the second depth (T2).Method according to one of the preceding claims, wherein at least one of the metallizations (4, 5) is structured before the introduction of the predetermined breaking lines (6a-6f) and subsequently the predetermined breaking lines (6a-6f) are introduced into the first surface side (3.1) of the ceramic layer (3) and / or the opposite second surface side (3.2) of the ceramic layer (3).Method according to one of the preceding claims, characterized in that the predetermined fracture lines (6a-6f) are introduced into the ceramic layer (3) in the form of a continuous or discontinuous predetermined fracture lines (6a-6f), wherein the continuous predetermined fracture lines (6a-6f) are formed in the form of slot-like depressions and the discontinuous predetermined fracture lines (6a-6f) are formed by a line-like arrangement of a plurality of shot craters in the surface side (3.1, 3.2) of the ceramic layer (3), which are arranged, for example, at a distance from one another and / or overlapping.Method according to Claim 2, characterized in that the enlarged first depth (T1) of the predetermined fracture lines (6a-6f) provided in the crossing regions (K1 to K9) is generated by subjecting the crossing regions (K1 to K9) to a laser beam of homogeneous power generated by the laser device a plurality of times or by subjecting the crossing regions (K1 to K9) to a laser beam of controllable power generated by the laser device a single time.Method according to claim 5, wherein the predetermined fracture lines (6a-6d) formed in the form of a continuous slot-like depression are generated by means of a laser device with controllable laser power, in particular by means of a diode laser, fiber laser or solid-state laser with different pulse durations.Method according to Claim 2, characterized in that the predetermined breaking lines (6a to 6f) are produced in the crossing regions (K1 to K9) with a first depth (T1) which is greater by 20% to 80% than the second depth (T2), wherein the second depth (T2) is preferably between 30 μm and 200 μm and / or the first depth (T1) is less than 80% of the material thickness of the ceramic layer (3).Method according to claim 2, wherein the break-off lines (6a to 6f) are produced in the crossing regions (K1 to K9) with a first depth (T1) such that the first depth (T1) extends over a length (L) of 0.2 mm to 20 mm.Method according to one of the preceding claims, wherein the predetermined fracture lines (6a to 6f) are introduced by means of the laser device in an oxygen-containing atmosphere, which preferably has an oxygen content of at least 30%.A base substrate (1) manufactured by a method according to any one of the preceding claims.

Images