Carrier substrate for electrical components and method for manufacturing such a carrier substrate - Patents.com

Abstract

A carrier substrate (1) for an electrical component (4) comprises a heat sink (20) and a ceramic element (71). The ceramic element (71) is at least partially bonded to the heat sink (20). In the manufactured carrier substrate (1), a bonding layer is formed between the heat sink (20) and the ceramic element (71) that does not contain a solder material. The adhesive layer of the bonding layer has a sheet resistance greater than 5 ohms / sq, more preferably greater than 10 ohms / sq, and most preferably greater than 20 ohms / sq.

Description

[Technical field]

[0001] The present invention relates to a carrier substrate for electrical components and to a method for manufacturing such a carrier substrate. [Background technology]

[0002] Heat sinks for cooling electrical or electronic components, in particular semiconductors such as laser diodes, are well known from the prior art. During operation, the electrical or electronic components generate heat, which is dissipated by the heat sink in order to ensure the long-term functionality of the electrical or electronic components. This is particularly true for laser diodes, where a temperature difference of just a few degrees Celsius can result in a significant decrease in performance and / or service life.

[0003] To cool a component, a heat sink, which is usually bonded to the component, typically has a cooling fluid channel system through which a cooling fluid flows during operation to absorb and remove heat emanating from the electrical or electronic component. Preferably, a fin structure is used here, in which several bridge-like elements protrude into the cooling fluid channel system in order to provide the largest possible contact surface with the cooling fluid, thus limiting the cooling fluid channel system or improving the heat transfer from the walls protruding into it to the cooling fluid. For example, heat sinks are used to cool laser diodes.

[0004] It is also common to use heat sinks to cool printed circuit boards which are formed as metal-ceramic substrates. Summary of the Invention [Problem to be solved by the invention]

[0005] To insulate the electrical components on the component side, insulating elements are typically embedded in a carrier substrate in which a heat sink is integrated, with ceramic elements proving to be particularly favorable due to their high insulating strength. However, the choice of material for the ceramic elements used for electrical insulation is limited by the manufacturing process of the carrier substrate, in particular by the bonding of the heat sink, so that, for example, the positive thermal properties of a Si3N4 substrate cannot be utilized for such a carrier substrate.

[0006] The present invention therefore aims to provide an improved carrier substrate with which an optimized heat dissipation can be achieved by improved material selection, in particular with regard to the ceramic elements. [Means for solving the problem]

[0007] This object is achieved by a carrier substrate according to claim 1 and a method according to claim 9. Further designs and embodiments can be found in the dependent claims, the description and the drawings. According to a first aspect of the present invention, A heat sink; a ceramic element, at least partially bonded to the heat sink; In the manufactured carrier substrate, a bonding layer is formed between the heat sink and the ceramic element, the bonding layer being free of solder material; A carrier substrate for electrical components is provided, wherein the adhesive layer of the bonding layer has a sheet resistance greater than 5 ohms / sq, more preferably greater than 10 ohms / sq, most preferably greater than 20 ohms / sq.

[0008] In contrast to the carrier substrates known from the prior art with a heat sink and a ceramic element, according to the present invention, a bonding layer is provided that does not contain solder material formed between the ceramic element and the heat sink, which bonding layer has a relatively high sheet resistance. In other words, the bonding process used for bonding to the ceramic element dispenses with solder material, and the manufacturing process also results in a relatively high sheet resistance being generated. This is especially the case when bonding to the ceramic element is performed by hot isostatic pressing, more preferably by hot isostatic pressing, in which an active metal layer is placed between the ceramic element and the metal layer to be bonded. This results in a bonding layer with a homogeneously distributed and relatively thin thickness (dimensioned along the stacking direction), which thickness is in particular essentially determined or established by the adhesive layer.

[0009] A bonding layer free of solder material is to be understood in particular as a bonding layer which is essentially or exclusively due to the active metal and has no additional components due to the solder base material or the solder material containing the active metal. In other words, more preferably, the bonding layer is essentially formed only by the adhesive layer. As a result of the bonding process, the active metal layer becomes the bonding layer or part of the bonding layer during use.

[0010] This, together with other parameters such as the purity of the applied active metal layer and / or the roughness of the ceramic element, contributes to the correspondingly resulting sheet resistance. The advantage of not using a solder material when bonding the metal layer to the ceramic element (leading to the claimed properties) is that the temperatures required during the bonding process of the heat sink do not affect the bond between the metal layer and the ceramic element. The heat sink is bonded in a subsequent step after bonding the metal layer to the ceramic element, in which the temperatures that would melt the solder material again if bonded via a solder material prevail. In contrast to bonding layers made of solder materials, i.e. bonding layers that contain solder materials, such bonding layers with the required sheet resistance have proven to be resistant to the temperatures present when bonding a heat sink to a metal-ceramic substrate. This advantageously makes it possible to provide a carrier substrate for which ceramic elements were previously unsuitable, since they could only be bonded to the metal layer via solder systems, in particular solder systems that cannot withstand the temperatures required for bonding the heat sink.

[0011] It is emphasized that the described bonding layer is arranged between the heat sink and the ceramic element, in particular formed on or adjacent to the cooling side of the ceramic element. In particular, it is emphasized that due to the manufacturing process, at least one metal part may be formed between the heat sink (in the form provided for the bonding process) and the ceramic element, or between the installed heat sink and the ceramic element, as viewed in the stacking direction. If this metal part is made of the same material as the heat sink used in the manufacturing process, there may be a smooth transition between the heat sink and this metal part. Thus, the skilled person will recognize that this metal part, which is not attributable to the heat sink originally used but is integrally bonded to the heat sink provided in the manufactured state, may be attributable to the heat sink in the manufactured state, or that a further metal layer or further metal part may be formed between the heat sink and the carrier substrate.

[0012] The carrier substrate can be, for example, a printed circuit board, in which conductor paths and / or connection areas are formed on the component side, provided for joining electrical components, in particular for forming an electrical circuit. Alternatively, it is conceivable that the carrier substrate is a cooling system, capable of cooling, for example, a laser diode or a laser diode device. Preferably, the heat sink is formed by stacking at least a first and a second metal layer on top of each other, the first and second metal layers being bonded to each other by a direct bonding method. Corresponding voids in the first and second metal layers can be used to create a cooling channel system, through which a cooling fluid, for example a cooling liquid or a cooling gas, can flow during operation in order to dissipate heat from the carrier substrate. For example, it is also conceivable that the heat sink is manufactured differently and / or provided with a fin structure. Regardless of the form of provision, it can be an open or closed cooling structure in the heat sink.

[0013] To determine the sheet resistance, first the metal layers and possibly the solder-based layers are removed from the manufactured carrier substrate, for example by etching. Then, by a four-point measurement, the sheet resistance is measured on the upper or lower side of the carrier substrate freed from at least one metal layer and the solder-based layer. In particular, the sheet resistance of a material sample should be understood as its resistance relative to a square surface area. It is customary to characterize the surface resistance in the unit Ω / sq (square). The physical unit of sheet resistance is the ohm.

[0014] Preferably, the carrier substrate is formed as a printed circuit board in which, in the manufactured state, at least one metal layer bonded to the ceramic element is structured. For example, for this purpose, after the bonding step, structuring is also carried out, for example by laser processing, etching and / or mechanical processing, whereby conductor paths and / or connections for electrical or electronic components are realized. Preferably, a further metal layer, in particular a back metallization, is provided on the ceramic element opposite the metal layer on the manufactured metal-ceramic substrate. The back metallization preferably serves to counteract deflections, and a heat sink is bonded to the back metallization and serves to effectively dissipate heat emanating during operation from the electrical or electronic components bonded to the printed circuit board or metal-ceramic substrate.

[0015] Copper, aluminum, molybdenum, tungsten, nickel and / or their alloys such as CuZr, AlSi or AlMgSi, as well as laminates such as CuW, CuMo, CuAl and / or AlCu, or MMCs (metal matrix composites) such as CuW, CuM or AlSiC, are considered as materials for the metal layer in the metal-ceramic substrate or for the metal of the heat sink. Furthermore, more preferably, at least one metal layer on the produced metal-ceramic substrate is surface modified, in particular as a component metallization. Surface modification includes, for example, sealing with noble metals, in particular silver and / or gold, or (electroless) nickel or ENIG (electroless nickel immersion gold), or edge encapsulation on the metallization to suppress crack formation or expansion.

[0016] Preferably, the thickness of the bonding or adhesive layer, measured in the stacking direction and averaged over a number of measurement points in a given area or in a number of areas running or proceeding parallel to the main extension plane, has a value of less than 1000 nm, more preferably less than 600 nm, most preferably less than 350 nm. When the term "multiple areas" is used, it is meant in particular that the metal layer is subdivided into areas of equal size and that at least one value for the thickness, more preferably several measurements, is recorded in each of these areas that subdivide the metal layer. The thicknesses thus determined at different points are arithmetically averaged.

[0017] In particular, the ceramic element has a material composition that cannot be bonded by direct bonding methods. Preferably, the ceramic element comprises silicon nitride. In particular, the ceramic element comprises more than 60 weight percent, more preferably 80 weight percent, most preferably more than 90 weight percent silicon nitride. Silicon nitride proves to be particularly advantageous, since it provides high thermal shock resistance and offers high bending strength. In addition, due to the increased thermal expansion coefficient, the formation of thermomechanical stresses is reduced. In addition, the improved thermal conductivity can improve the efficiency of heat dissipation. Due to the hot isostatic pressing used in the manufacture of metal-ceramic substrates, it proves to be particularly advantageous that silicon nitride can also be used in such carrier substrates. Finally, silicon nitride cannot be bonded to metal layers, in particular copper layers, using direct bonding methods, and the solder material required has a melting temperature below 1000 ° C, so that in the direct bonding method of the heat sink, the solder material is melted again. Thus, the present method, which is structurally reflected in a solderless bonding layer with increased surface resistance, also allows the use of silicon nitride in the corresponding carrier substrate. Furthermore, preferably the ceramic element, in particular the silicon nitride ceramic, has a thermal conductivity of more than 90 W / mK, more preferably more than 110 W / mK, most preferably more than 120 W / mK. Furthermore, it is envisaged that the ceramic element has a thickness of less than 300 μm, more preferably less than 250 μm, most preferably less than 200 μm.

[0018] Alternatively, the ceramic element comprises as ceramic material Al2O3, 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% of theoretical density), TSZ (tetragonal stabilized zirconium oxide). It is also conceivable that the ceramic element is formed as a compound ceramic or hybrid ceramic, in which case several ceramic layers that differ in terms of their material composition are placed on top of each other and bonded to each other to form the ceramic element in order to combine various desired properties. Preferably, the ceramic element does not contain parylene.

[0019] In particular, the heat sink is bonded to the ceramic element via a back metallization, and preferably the adhesive layer is formed between the back metallization and the ceramic element. The back metallization assigned to the heat sink is bonded to the ceramic element in a pre-manufacturing step, and the heat sink is bonded only after the back metallization has been bonded. As a result, the back metallization part and the heat sink are subjected to different temperature treatments, which is reflected in different grain sizes. As a result, these parts can be recognized on the finished substrate.

[0020] Preferably, the grain size in the backside metallization is different from the grain size in the heat sink. The backside metallization can also be achieved in the manufacturing process by fixing the metal layer to be bonded in the metal bag during hot isostatic pressing, which will bond the metal layer and part of the metal bag, so that structural differences can also be detected when different pure metal materials are used for the metal layer and the metal bag.

[0021] For example, the bond layer between the backside metallization and the ceramic element contains active metal content that may come from an active metal layer used in the manufacturing process. Furthermore, it is conceivable that the back metallization protrudes along the main extension surface relative to the heat sink. The heat sink is bonded to the back metallization already bonded to the ceramic element and preferably does not extend over the entire back surface of the ceramic element, allowing the back metallization to be larger. This means that the back metallization, which is preferably bonded to the ceramic element over the entire front surface, does not have to be partially removed again. This also simplifies the positioning of the heat sink relative to the back metallization during manufacture, since it does not have to have an absolutely matching arrangement.

[0022] Preferably, the heat sink is formed from at least a first metal layer and a second metal layer, which are preferably bonded onto one another by a direct bonding method, in particular a solderless direct bonding method, the first metal layer and / or the second metal layer having recesses forming cooling channels in the manufactured carrier substrate. It is also conceivable that the cooling channels extend to the ceramic element and / or that a residual metal layer thickness is provided almost exclusively, more preferably exclusively, between the ceramic element and the cooling channel. In order to form cooling channels that extend to the carrier substrate or the ceramic element, in the manufacturing process, after bonding the back metallization to the ceramic element, the back metallization is structured to expose corresponding areas on the ceramic element before the bonding process of the heat sink to the back metallization is carried out.

[0023] Preferably, the distance between the sides defining the cooling channels is less than 0.5 mm, more preferably less than 0.4 mm, most preferably less than 0.3 mm. In particular, this refers to sides spaced apart in a direction parallel to the main extension surface. Such relatively thin channels and distances between the sides can be produced, for example, by erosion or wire cutting in the respective metal layers. Such thin cooling channels prove to be particularly advantageous, since they ensure a high efficiency in the transfer of heat and can also provide a particularly uniform and homogeneously distributed cooling or heat transfer possible on the cooling side.

[0024] Preferably, the thickness of the bonding layer or adhesive layer, measured in the stacking direction and averaged over a number of measurement points in a given area or in a number of areas running or proceeding parallel to the main extension plane, has a value of less than 1000 nm, more preferably less than 600 nm, most preferably less than 350 nm. When the term "a number of areas" is used, it is meant in particular that the metal layer is subdivided into areas of as equal size as possible and at least one value for thickness, more preferably several measurements, is recorded in each of these areas that subdivide at least one metal layer. The thicknesses thus determined at different points are arithmetically averaged.

[0025] Thus, compared to carrier substrates known from the prior art, a relatively thin bonding layer is formed between the at least one metal layer and the ceramic element. To determine the relevant thickness of the bonding layer, the measured thickness is averaged over a number of measurement points within a given or defined area or areas.

[0026] In particular, the adhesive layer comprising the active metal has a substantially constant thickness. In particular, the thickness measurements determined in one or more regions have a distribution to which a standard deviation of less than 0.2 μm, more preferably less than 0.1 μm, most preferably less than 0.05 μm is assigned. In particular, the physical and / or chemical vapour deposition of the active metal layer and the resulting bonding layer makes it possible to achieve a homogeneous and evenly distributed thickness of the bonding layer, in particular consisting of the adhesive layer only. The adhesive layer can also have a constant thickness if it is formed in addition to the solder base material.

[0027] A further object of the invention is a method for manufacturing a substrate according to the invention, comprising the steps of bonding, by hot isostatic pressing, a backside metallization and preferably a component metallization to a ceramic element to form a metal-ceramic substrate; - providing a heat sink, in particular a heat sink having a cooling channel structure; - bonding said heat sink to said backside metallization by a direct bonding method, in particular by the DCB method.

[0028] All the described advantages and properties of the carrier substrate are equally applicable and transferable to the present method and vice versa. Preferably, during hot isostatic pressing, the metal container or the metal layer is subjected to a gas pressure of 100 to 2000 bar (10 to 200 MPa), more preferably 150 to 1200 bar (15 to 120 MPa), most preferably 300 to 1000 bar (30 to 100 MPa) and a processing temperature of 300° C. up to the melting temperature of the metal layer, in particular to a temperature below the melting temperature. Advantageously, it has been shown that it is possible to bond metal layers, such as component metallizations and / or backside metallizations, to ceramic elements without the necessary temperatures of direct metal bonding processes, such as DCB or DAB processes, and without solder-based materials or solder materials used for active soldering. In addition, the use or application of an appropriate gas pressure makes it possible to produce metal-ceramic substrates that are as void-free as possible, i.e. without gas inclusions between the metal layer and the ceramic element. In particular, the process parameters mentioned in DE 2013113734 A1 are used, which are expressly referred to herein. It has also been shown that the bond between the ceramic element and the metal layer produced in this way can withstand temperatures in excess of 1050°C.

[0029] In particular, the method of the invention is characterized by the fact that the joining of the back metallization to the ceramic element is not performed as part of a soldering process, but as part of a hot isostatic pressing process. This makes the bond between the component metallization or back metallization on one side and the ceramic element on the other side more resistant, in particular with respect to the temperatures used when joining the heat sink to the metal ceramic substrate. In particular, the heat sink is joined to the back metallization of the metal ceramic substrate produced by hot isostatic pressing. As a result, there is no need to rely on solder-based joining methods to use ceramic elements that cannot be joined to a metal layer by a direct joining method. The described method therefore also allows the joining of such ceramic elements that could not previously be used to form the described carrier substrate, since the solder material used would be damaged or even destroyed in the joining process of the heat sink.

[0030] Preferably, the voids in the first metal layer or the second metal layer are realized by etching, erosion and / or milling, and at least the first and second metal layers are bonded together to form a heat sink, which provides a heat sink for the bond and a corresponding heat sink providing a cooling channel system capable of guiding a cooling fluid to dissipate heat in the manufactured carrier substrate.

[0031] Preferably, an active metal layer is arranged between the ceramic element and the component metallization on the other side or the back metallization, which provides a particularly strong bond between the back metallization and the ceramic element during hot isostatic pressing, the active metal layer significantly contributing to the formation of an adhesive or bonding layer, in particular the active metal layer becoming an adhesive layer, in particular a bonding layer, after the manufacturing process.

[0032] In particular, by using a separately designed active metal layer, it is possible to make the active metal layer relatively thin, thus realizing a relatively thin thickness of the bonding layer according to the claims, especially averaged over different measurements in one or more defined areas. Examples of active metals are titanium (Ti), zirconium (Zr), hafnium (Hf), chromium (Cr), niobium (Nb), cerium (Ce), tantalum (Ta), magnesium (Mg), lanthanum (La), and vanadium (V). It should be noted that the metals La, Ce, Ca, and Mg can be easily oxidized. It should also be noted that the elements Cr, Mo, and W are not classical active metals, but are suitable as a contact layer between Si3N4 and at least one metal layer or solder system or solder material, since they do not form an intermetallic phase with at least one metal layer, for example copper, and do not have solid solubility.

[0033] Preferably, the active metal is deposited on the solder base material and / or the at least one metal layer and / or the ceramic element by physical and / or chemical vapor deposition, for example by sputtering, to produce a relatively thin active metal layer, which in turn results in a relatively thin bonding layer, in particular a homogeneous and thin adhesive layer. It is also conceivable to provide the active metal layer on the ceramic element and / or on the metal layer for the component metallization and / or backside metallization using plasma, in vacuum and / or by vapor deposition. It is also conceivable to realize the active metal layer by electroplating. Most preferably, the active metal layer is provided as a foil.

[0034] The active metal layer can be applied in particular by gas physical deposition, thus making it possible to achieve a relatively thin active metal layer, which can also contribute to achieving the required surface resistance. Galvanic, electroless and / or thermal deposition, or deposition by cold gas spraying, are also conceivable.

[0035] Preferably, the ratio between the thickness of the active metal layer and the thickness of the first and / or second metal layer has a value of 0.0001 to 0.005, more preferably 0.005 to 0.003, most preferably 0.001 to 0.0015. Thus, a relatively thin active metal layer is advantageous to achieve an effective bonding layer while limiting the consumption of active metal.

[0036] Preferably, the bonding of the heat sink to the back metallization is realized by hot isostatic pressing after forming the metal ceramic substrate. The metal ceramic substrate is formed first to ensure that bending due to thermomechanical stresses in the metal ceramic substrate is prevented during the formation process of the metal ceramic substrate by ensuring that the thicknesses of the back metallization and the component metallization are as equal or comparable as possible. In other words, the metal ceramic substrate with the component metallization and the back metallization is manufactured first to prevent bending of the metal ceramic substrate after or during the bonding process, which is a result of the different thermomechanical expansion coefficients of the ceramic element and the metal layer. It is then easier to bond the heat sink, especially through its cover layer, to such an essentially flat and uniform metal ceramic substrate. Otherwise, the metal ceramic substrate must be painstakingly straightened if this is still possible. In addition, it has been shown that a metal layer larger than 0.4 mm bonded to the ceramic element causes larger thermomechanical stresses after cooling, which also remain after cooling.

[0037] Further advantages and properties emerge from the following description of preferred embodiments of the subject matter according to the invention, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0038] [Figure 1] 2 is a schematic diagram of a carrier substrate according to an exemplary embodiment of the present invention; [Diagram 2] 2 is a schematic exploded view of a carrier substrate according to an exemplary embodiment of the present invention; [Diagram 3] FIG. 2 is a schematic diagram of a first metal layer for the heat sink of FIG. 1. [Figure 4] 4 is a schematic diagram of a carrier substrate according to a further exemplary embodiment of the present invention; [Diagram 5] FIG. 2 is a detailed view of a system comprising a carrier substrate having a distribution structure. [Figure 6] FIG. 2 is a detailed view of a system comprising a carrier substrate having a distribution structure. [Figure 7] FIG. 2 is a detailed view of a system comprising a carrier substrate having a distribution structure. [Figure 8] FIG. 2 is a detailed view of a system comprising a carrier substrate having a distribution structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] FIG. 1 shows a schematic representation of a carrier substrate 1 according to a preferred embodiment of the invention. Such a carrier substrate 1 is provided in particular to enable electrical components 4 to be bonded at their component side 5. For example, the carrier substrate 1 may be a printed circuit board provided with a plurality of connection areas and conductor paths and contact areas on which circuits are realized. It is also conceivable that the carrier substrate 1 is essentially a cooling structure provided specifically for cooling electrical components such as laser diodes or laser diode devices. To dissipate the heat generated by the electrical components 4 during operation, the carrier substrate 1 comprises a heat sink 20. This heat sink 20 is formed on a cooling side 6 opposite the component side 5. Preferably, the heat sink 20 is a metal structure formed by stacking at least a first metal layer 21 and a second metal layer 22 on top of each other and then bonding at least one metal layer 21 and the second metal layer 22 together. It is possible to realize a channel system in the heat sink 20 by recesses embedded in the first metal layer 21 and / or the second metal layer 22. A cooling fluid, e.g. a cooling gas or a cooling liquid, can be guided through this channel system in order to properly dissipate heat from the carrier substrate 1. To insulate the electrical component 4, in particular from the metallic heat sink 20, the carrier substrate 1 comprises a ceramic element 71. Preferably, the carrier substrate 1 comprises a metallic ceramic substrate 70 and a heat sink 20, which are bonded together to form the carrier substrate 1. Preferably, the metallic ceramic substrate 70 provides a component metallization 72 on the component side of the ceramic element 71 and a back metallization 74 on the cooling side 6 of the ceramic element 71 of the metallic ceramic substrate 70 opposite the component side 5. The thicknesses of the component metallization 72 and the back metallization 74 correspond to each other in order to compensate for thermomechanical stresses caused by different thermal expansion coefficients of the back metallization 74 / component metallization 72 on one side and the ceramic element 71 on the other side, in particular in the manufacturing step in which the bonding of the component metallization 72 and the back metallization 74 to the component side of the ceramic element 71 takes place. Without such compensation, the metallic ceramic substrate 70 tends to warp.Therefore, the heat sink 20 is preferably bonded to a metal-ceramic substrate 70, in particular to the backside metallization 74 of an already manufactured metal-ceramic substrate 71. The bonding of the cover layer of the heat sink 20 to the backside metallization 74 is preferably performed by a direct bonding method, in particular a solderless direct bonding method, which requires a temperature above 1068° C. to produce a eutectic formed between the backside metallization 74 and the cover layer of the heat sink 20. In the illustrated embodiment, the first metal layer 21 forms the cover layer.

[0040] Preferably, the first metal layer 21 and the second metal layer 22 are already compounded with each other during the bonding process of the heat sink 20 to the metal-ceramic substrate 1. Alternatively, it is conceivable that the bonding between the first metal layer 21 and the second metal layer 22 and the bonding between the cover layer of the heat sink 20 and the backside metallization 74 are performed simultaneously or at least overlapping in time. It is conceivable that the first metal layer 21 forms a cover layer (see embodiment of FIG. 1) and / or that the cover layer is an additional layer bonded to the upper side of the heat sink 20. It is for example conceivable that the cover layer forms a continuous metal layer without voids.

[0041] The need to bond the heat sink 20 to the metal ceramic substrate 1, in particular to the back metallization 74, by a direct bonding method and therefore at the corresponding temperature means that the bond already formed between the ceramic element 71 and the component metallization 72 or back metallization 74 must also withstand the manufacturing conditions for bonding the heat sink 20 to the metal ceramic substrate 1. Otherwise, the manufacturing conditions used, which are required as part of the bonding of the heat sink 20 to the metal ceramic substrate 70, would again loosen or at least damage the bond between the back metallization 74 or the component metallization 72 and the ceramic element 71. This is especially the case if a solder material with a melting temperature below 1000° C. has to be used for bonding the component metallization 72 or the back metallization 74 to the ceramic element 71.

[0042] However, this also has the consequence that such ceramic elements 71 are excluded from use in the described carrier substrate 1, which can only be bonded to a metal layer (i.e. the component metallization 72 or the backside metallization 74) via a solder material. This is for example the case for silicon nitride, which cannot be bonded to metal using direct bonding methods. In order to also use such ceramic elements in the above-mentioned carrier substrates, which would otherwise have to be excluded, the present invention provides for bonding the component metallization or the backside metallization to the ceramic element 71 by a solder-free bonding process, in particular by solder-free hot isostatic pressing.

[0043] In particular, as part of the bonding process, during hot isostatic pressing, an active metal layer is arranged between the ceramic element 71 and the component metallization 72 and / or between the ceramic element 71 and the back metallization 74. This is deposited, for example, before hot isostatic pressing, for example by gas physical deposition, for example by a sputtering process or by electrochemical methods, on the component side 5 or the cooling side 6 of the ceramic element 71 and / or on the component metallization 72 and / or the back metallization 74. It has been found that bonding between the ceramic element 71 and the component metallization 72 or the back metallization 74 is possible, in particular for ceramic elements 71 that are not accessible by a direct metal bonding process. At the same time, it has also been found that the bond can withstand the temperatures required for a direct bonding method to the metal-ceramic substrate 70 of the heat sink 20. This is in particular due to the fact that the bonding between the ceramic element and the metal layer can be performed in this case without a solder material or a solder-based material.

[0044] It is emphasized again that the active metal layer is an active metal layer with a proportion of active metal greater than 15 weight percent, more preferably greater than 30 weight percent, most preferably greater than 70 weight percent. It is therefore not an active metal-containing solder layer, as is usual when joining component metallization 72 to ceramic element 71. This makes it possible to use ceramic elements 71 that are particularly preferred for example due to their high thermal conductivity or that are advantageous for forming a corresponding carrier substrate 1. This applies in particular to carrier substrates 1 in which ceramic element 71 comprises silicon nitride or is formed from more than 80% silicon nitride.

[0045] The described bonding method preferably comprises the step of: - characterized by the fact that it has a bonding layer between the ceramic element 71 and the component metallization 72 and / or between the ceramic element 71 and the back metallization 74, the sheet resistance of which is greater than 5 ohms / sq, more preferably greater than 15 ohms / sq, most preferably greater than 20 ohms / sq. The stated sheet resistance is in particular the result of a uniformly applied active metal layer and bonding by hot isostatic pressing. In contrast, a bonding layer produced using a solder material with active metal components has a lower sheet resistance. In particular, only an adhesive layer is formed as a bonding layer between the back metallization 74 or the component metallization 72 and the ceramic element 71, i.e. no sub-areas due to the solder material can be discerned in the produced carrier substrate 1.

[0046] The bonding process of the back metallization 74 to the cover layer of the heat sink 20 as part of the direct bonding method means that no border / transition area can be discerned in the manufactured transition between the back metallization 74 and the upper side of the heat sink 20, so that the back metallization 74 is part of the heat sink 20 in the manufactured state. A sheet resistance is therefore formed between the ceramic element 71 and the heat sink 20, to which the original back metallization 74 of the metal ceramic substrate 1 in the manufactured state is added. The metal ceramic substrate manufactured according to the method of the invention can therefore be recognized by the fact that a corresponding sheet resistance is formed between the ceramic element 71 and the heat sink 20. In addition, a bonding layer is formed, which is formed not in particular as a solder material but only as an adhesive layer.

[0047] Furthermore, a serpentine or loop-shaped channel system is formed in Fig. 1 into which, for example, a cooling fluid can be introduced via an inlet E, which is guided through the heat sink 20 in a loop or serpentine shaped movement and finally leaves the heat sink 20 again through an outlet opening A. In the following figures further examples of heat sinks are given which can be provided for certain embodiments of the invention and which can be bonded to a metal-ceramic substrate 70, in particular its backside metallization.

[0048] 2 shows diagrammatically an exploded view of a heat sink 1 according to a first preferred embodiment for the subject matter according to the present invention. In particular, the heat sink 1 is provided for cooling an electronic or electrical component (not shown), in particular a semiconductor element, most preferably a laser diode. To cool the electrical or electronic component, the manufactured heat sink 1 forms a cooling fluid channel system through which a cooling fluid can be conducted during operation, so that the cooling fluid can absorb and remove the heat released by the electronic or electrical component during operation.

[0049] For this purpose, a supply area and a discharge area are preferably provided in the heat sink 1, in particular a cooling fluid channel system (not shown), in which the cooling fluid is introduced via the supply area and discharged again via the discharge area. Preferably, the cooling fluid channel system is provided in such a way that during the transition from the supply area to the discharge area the cooling fluid 1 passes through a fin structure 25, which in particular projects into the cooling fluid channel system. The fin structure 25 is preferably a web-like element 7, which projects into the cooling fluid channel system in order to provide the largest possible contact surface for the fluid, allowing an effective heat transfer from the web-like element 7 or the wall of the cooling channel system to the fluid.

[0050] Preferably, the heat sink 1 comprises at least one first metal layer 11, at least one second metal layer 12 and / or at least one third metal layer 13. To form the cooling fluid channel system, the at least one first metal layer 11, at least one second metal layer 12 and / or at least one third metal layer 13 are structured with at least one void 21, 22 so as to form the cooling fluid channel system by stacking one on top of the other or laying one on top of the other along the stacking direction S.

[0051] In particular, the at least one first metal layer 11, the at least one second metal layer 12 and / or the at least one third metal layer 13 are each structured in a different way or are provided with different paths of voids 21, 22. In particular, the at least one first metal layer 11, the at least one second metal layer 12 and / or the at least one third metal layer 13 form in the at least one void 21, 22 at least one first portion 21, which first portion 21 has web-like elements 7 extending in a main extension plane HSE, which extends in particular perpendicular to the stacking direction S. In addition to the first portion 21 of the at least one void 21, 22 in the at least one first metal layer 11, it is preferred that a second portion 22 of the at least one void 21, 22 in the at least one first metal layer 11 is provided for supplying or discharging cooling fluid into or from the first portion 21 or forms part of a supply area and / or a discharge area.

[0052] The heat sink 1 is preferably limited in the stacking direction S by the upper cover layer 15 and the lower cover layer 14, with the at least one first metal layer 11, the at least one second metal layer 12 and / or the at least one third metal layer 13 being arranged between the lower cover layer 14 and the upper cover layer 15, as viewed in the stacking direction S. In particular, the formation of the at least one first metal layer 11, the at least one second metal layer 12 and / or the at least one third metal layer 13 is arranged sandwich-like between the upper cover layer 15 and the lower cover layer 14. In addition to the at least one cavity 21, 22 consisting of the first portion 21 and the second portion 22, it is preferred that the heat sink 1 or the at least one first metal layer 11 has a further cavity 24, which is not part of the cooling fluid channel system, having a fin structure 25. Furthermore, it is preferred that the upper cover layer 15 and / or the lower cover layer 14 are provided with a connection region 30. In particular, the electric or electronic component is joined to this connection area 30 above or below the fin structure 25, which extends in particular in the stacking direction S, preferably in a direction perpendicular to the stacking direction S. In other words, the fin structure 25, in particular its web-like elements 7, extend below the connection area 30, preferably parallel thereto. By correspondingly arranging the fin structure 25 of the web-like elements 7 above or below the connection area 30, the electric or electronic component can be effectively cooled by the fin structure 25.

[0053] FIG. 3 shows a schematic view of at least one first metal layer 11, for example as installed in FIG. 1. In the illustrated embodiment, the fin structure 25 is formed from web-like elements 7, which extend to different lengths when viewed in the main extension plane HSE. In particular, the length of the web-like elements 7 increases towards the central axis M of the at least one first metal layer 11. As a result, it is advantageously possible to maximize the cooling effect, in particular in the central region of the connection area 30. Furthermore, it is conceivable that the web-like elements extend parallel and / or at an angle to the central axis M. Preferably, the shape of the web-like elements 7, in particular the length and / or the inclination of the web-like elements 7 with respect to the central axis M along the main extension plane HSE, is determined or defined by the corresponding requirement profile for cooling the corresponding electric or electronic component.

[0054] In order to achieve the smallest possible distance A1 between two adjacent web-like elements 7, for example a first portion 21 of at least one void 21, 22 in the at least one first metal layer 11 is produced by erosion, in particular by spark erosion. In particular this includes production by wire erosion.

[0055] Furthermore, the second portion 22 of at least one void 21, 22 is performed by etching. Preferably, etching is performed in particular in the large area of ​​the second portion 22 of the void 21, 22, i.e. in the later supply and / or discharge area formed for supplying and discharging the cooling fluid. In contrast, erosion is provided in particular for the microstructuring shaping of the void 21, 22, i.e. the first portion 21 of the void 21, 22. It has been found that this makes it possible to produce a relatively very small distance between the web-like elements 7 without having to rely on several first metal layers 11 with the etched first portion 21 of at least one void 21, 22, which have to be stacked on top of each other to achieve the smallest possible distance between the two web-like elements 7. Preferably, the distance A1 between the opposing side walls of two web-like elements 7 is less than 0.4 mm, more preferably less than 0.3 mm, most preferably less than 0.2 mm. This makes it possible to incorporate as many web-like elements 7 as possible into the fin structure 25. Thus, the contact surface between the cooling fluid and the walls of the cooling fluid channel system can be increased accordingly, so that the cooling effect can be increased.

[0056] Preferably, the at least one first metal layer 11, the at least one second metal layer 12, the at least one third metal layer 13, the upper cover layer 15, and / or the lower cover layer 14 have a thickness, measured in the stacking direction S, of 0.2-0.7 mm, more preferably 0.35-0.6 mm, and most preferably 0.3-0.4 mm. Preferably, the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 each form the same thickness. Furthermore, preferably, the microstructures of the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 are fused or fused together by corresponding temperature treatments, whereby the at least one first metal layer 11, the at least one second metal layer 12, and / or the at least one third metal layer 13 are formed as part of a sintering process to form an integral cooling fluid channel system.

[0057] Furthermore, the upper cover layer 15 and / or the lower cover layer 14 also each have at least one cavity 21, 22 and / or a further cavity 24, the upper cover layer 15 and / or the lower cover layer 14 preferably not containing any part of the web-like element 7 or the subsequent fin structure 25. The further cavity 24 is preferably used for mounting or fixing the heat sink 1.

[0058] FIG. 4 shows a schematic representation of a metal-ceramic substrate 70 according to a further exemplary embodiment of the invention. Such a metal-ceramic substrate 1 preferably serves as a carrier for electronic or electrical components 4, which can be connected to the metal-ceramic substrate 70. The essential components of such a metal-ceramic substrate 1 are a ceramic element 71 extending along the main extension plane HSE and a component metallization 72 bonded to the ceramic layer 71. The ceramic element 71 is made of at least one material, including ceramic. The component metallization 72 and the ceramic element are arranged on top of each other along a stacking direction S, which extends perpendicular to the main extension plane HSE, and are connected to each other by a material bond. In the manufactured state, the component metallization 72 is structured on the component side 5 of the metal-ceramic substrate 70 in order to form conductor paths or connection points for the electrical components 4. In the illustrated embodiment, the metal-ceramic substrate 70 comprises a secondary layer 73 and a metal intermediate layer 75 arranged between the ceramic element 71 and the secondary layer 73. The ceramic element 71, the metal interlayer 75 and the secondary layer 13 are arranged on top of each other along the stacking direction S. Furthermore, the metal interlayer 75 is thicker than the ceramic element 71 and / or the secondary layer 73. Preferably, the metal interlayer 75 is thicker than 1 mm, more preferably than 1.5 mm, most preferably than 2.5 mm. However, it is also conceivable that only the ceramic element 71 with the component metallization 72 and the backside metallization is formed to form a metal-ceramic substrate. The ceramic element 71 is preferably made of ceramic and is designed to form sufficient insulation strength and reinforce the metal-ceramic substrate 1, while the secondary layer 73 may be made of, for example, tungsten or molybdenum, since no significant insulation strength is required here. This reduces material costs. Alternatively, the secondary layer 73 is also made of a material that includes ceramic.

[0059] The metallic heat sink 20 is provided on the cooling side 6 of the metal-ceramic substrate 1 opposite the component side 5. The metallic heat sink 20 is preferably bonded directly to the secondary layer 73. However, it is also conceivable for the heat sink 20 to be bonded directly to the rear metallization of the metal-ceramic substrate 1 or to the ceramic element 71 of the metal-ceramic substrate 1. This makes it possible to avoid interfaces formed with the corresponding connection material, which would otherwise adversely affect the thermal conductivity and thus limit the heat removal from the component side 5 to the cooling side 6.

[0060] For example, the cooling structure 20 is directly bonded to the secondary layer 73, the backside metallization and / or the ceramic element 71 by the AMB, DCB (direct copper bonding) or DAB (direct aluminium bonding) method. In particular, a plurality of fluid channels 30 are integrated into the metallic cooling structure 20. For the sake of clarity, only one of these fluid channels 30 is shown by way of example in FIG. 1 . The fluid channels 30 serve to guide the fluid, in particular the cooling fluid, in a targeted manner within the metallic cooling structure 20. The fluid is supplied to the cooling structure 20 via a distribution structure 40 and is discharged again via the distribution structure 40. Preferably, the distribution structure 40 has for this purpose an inlet portion 41 and an outlet portion 42.

[0061] In particular, the fluid channel 30 has an inlet opening 31 and an outlet opening 32 spaced apart from the inlet opening 31. The inlet opening 31 and the outlet opening 32 are part of an outer side A of the cooling structure 20 facing the distribution structure 40. In particular, the inlet portion 31 of the distribution structure 40 is adjacent to the inlet opening 31 and the outlet portion 42 is adjacent to the outlet opening 32.

[0062] In figures 4 to 6 only the metal cooling structure 20 and the distribution structure 40 are shown in perspective views, while in figures 7 and 8 they are shown in two different side views. In the figures, instead of the entire cooling structure 20, some fluid channels 30 of the cooling structure 20 are shown. In other words, the fluid channels 30 are shown here without the metal body in which they are embedded. Furthermore, as viewed in the stacking direction S, a supply structure 50 adjoins the underside of the distribution structure 40. As viewed in the stacking direction S, the distribution structure is therefore arranged between the cooling structure and the supply structure. Such a supply structure 50 is preferably provided for predetermining a first main flow direction HS1. For example, the supply structure is channel-shaped. Furthermore, the supply structure 50 comprises at least one inlet and one outlet (not shown here) to which a fluid circuit can be connected, or a cooling fluid supply and a cooling fluid waste. The distribution structure 40 is preferably designed to divert or introduce a fluid into the cooling structure 20 from a flow flowing along the first main flow direction HS1. Moreover, for the sake of clarity, the figures show only a single row of fluid channels 30. Preferably, several rows are arranged adjacent to each other or one after the other in a direction perpendicular to the row direction RR and parallel to the main extension plane HSE, each of which is supplied with fluid via a corresponding distribution structure 40, for example a single distribution structure. Preferably, these several rows extend completely through the outer side A of the cooling structure 20 facing the distribution structure.

[0063] In particular, several fluid channels 30 are arranged adjacent to one another. In particular, in the embodiment shown, the fluid channels 30 are arranged along rows which in the example shown extend essentially perpendicular to the first main flow direction HS1. Basically, it is also conceivable that the rows extend along a row direction RR inclined at an angle between 0 and 90° to the first main flow direction HS1. Preferably, this angle is less than 45°.

[0064] In the embodiment shown in figures 4 to 8, the distribution structure 40 deflects the fluid in such a way that at least a part of the fluid is first deflected from the first main flow direction HS1 into a transverse direction Q extending parallel to the row direction and then directed towards the inlet opening 31. In addition, the fluid is deflected towards the cooling structure 20, i.e. upwards, in the direction of the inlet opening 31. As a result, the distribution structure can supply several inlet openings 31 of different fluid channels 30 with fluid of the same temperature. For this purpose, the inlet portion 41 is designed as a wall-like structure which in the illustrated embodiment extends essentially parallel to the row direction RR. Preferably, the supply structure 50 supplies fluid only to a part of the distribution structure 40. In the illustrated embodiment, essentially a first part, in particular the left half, of the inlet portion 41, as viewed along the first main flow direction HS1, is flushed with the cooling fluid. However, the entire row of fluid channels 30 is supplied with fluid by the distribution structure 40. Preferably, the inlet portion comprises a ramp-like structure inclined as viewed in the row direction RR, in particular inclined with respect to the main extension plane HSE.

[0065] After passing through the fluid channels 30, the fluid leaves the cooling structure 20 through the outlet openings 32 and is guided into the outlet portion 42 of the distribution structure. The outlet portion 42 of the distribution structure 40 is also designed as a wall-like structure extending substantially parallel to the column direction RR. In particular, the outlet portion 42 is configured to collect the fluid leaving the outlet openings and deflect it in the second main flow direction HS2 back into the supply structure 50. For example, the outlet portion 42 includes a ramp-like structure inclined in the column direction RR, in particular inclined in the opposite direction to the ramp-like structure in the inlet portion 41 of the distribution structure 40. Furthermore, the first main flow direction HS1 and the second main flow direction HS2 are offset parallel to each other. In other words, after leaving the distribution structure 40, the flow of the fluid is offset transversely or laterally with respect to the flow as it flows towards the distribution structure 40.

[0066] In the illustrated embodiment, the inlet portion 41 of the distribution structure 40 is disposed forward of the outlet portion 42 of the distribution structure 40, as viewed along the first main flow direction HS1. However, the outlet portion 42 is disposed forward of the inlet portion 31 of the distribution structure 40, as viewed along the first main flow direction HS1.

[0067] The individual fluid channels 30 are preferably U-shaped, the U-shaped fluid channels 30 having two rim regions 34 extending substantially perpendicular to the main extension surface HSE and a transverse region 33 connecting the two rim regions 34. In particular, the transverse region 33 serves to deflect the fluid and is closest to the secondary layer 13 or ceramic layer 11 in the installed state. Preferably, the distance between the transverse region 33 and the ceramic layer 11 or secondary layer 13 adjacent to the cooling structure 20 has a value of 0.2-1.5 mm, more preferably 0.4-1, most preferably 0.6 mm-0.8 mm. Preferably, the fluid channels 30, in particular their rim regions 34, are designed such that the fluid swirls in the fluid channels 30. For this purpose, for example, the opening cross sections Q1, Q2 of the rim regions 34 running parallel to the main extension surface HSE are displaced laterally along the flow direction of the fluid in the fluid channels 30, in particular in the rim regions 34. The rim region 34 comprises a first subsection T1 with a first opening cross section Q1 and a second subsection T2 with a second opening cross section Q2, the first opening cross section Q1 being offset from the second opening cross section Q2 by an offset distance V when viewed in a direction parallel to the main extension plane HSE. Preferably, the first opening cross section Q1 and the second opening cross section Q2 are of the same size. However, it is also conceivable that the first opening cross section differs from the second opening cross section. In particular, the first subsection T1 and the second subsection T2 are each assigned to a metal layer that is, for example, stacked on top of one another during manufacture. The individual metal layers may be of the same thickness or of different thicknesses. It is also conceivable, for example, that the thickness of the individual layers decreases and / or increases in the direction of the component side.

[0068] In particular, the first opening cross section Q1 and the second opening cross section Q2 are offset relative to each other in a direction parallel to the first main flow direction HS1 or the second main flow direction HS2 and in a direction parallel to the row direction RR, i.e. in two directions that are not parallel to each other. Preferably, the ratio of the overlap area, where the first opening cross section Q1 and the second opening cross section Q2 are arranged one above the other in the stacking direction S, to the first opening cross section Q1 or the second opening cross section Q2 has a value of 0.5 to 0.9, more preferably 0.5 to 0.8, most preferably 0.5 to 0.7. In particular, it is conceivable that the opening cross section of the inlet opening and / or the outlet opening is larger than the first opening cross section and / or the second opening cross section. This allows funnel-shaped inlet and outlet areas to be formed for the fluid channels.

[0069] However, it is also conceivable that the first opening cross section Q1 and the second opening cross section Q2 are of different sizes. Preferably, the first and second opening cross sections are designed to form an essentially helical path for the fluid channel 30. The fluid channel 30 can be realized, for example, by stacking metal layers with corresponding openings, i.e. at least the first metal layer 11 and the second metal layer 12, or by a 3D printing process. Furthermore, the inlet opening 13 has a first opening cross section, the diameter and / or the edge length of which have a value between 0.1 mm and 2.5 mm, more preferably between 0.5 mm and 1.5 mm, most preferably essentially 1 mm. Preferably, the first opening cross section Q1 or the second opening cross section Q2 does not vary within the rim region 34 of the fluid channel 30.

[0070] Furthermore, preferably the further distance A2 between two adjacent rim regions of the same fluid channel has a value between 0.1 mm and 5 mm, more preferably between 0.2 mm and 2 mm, most preferably substantially 1.5 mm. The further distance A2 between the centres of two of the first cross-sectional openings Q1 or the second cross-sectional openings Q2 is measured at the same height in the stacking direction S.

[0071] In addition to the heat sink 20 or carrier substrate 1 described above, other heat sinks 20 with different geometries are also conceivable. For example, it is also conceivable that the heat sink 20 is formed from an essentially flat unstructured metal body 20. However, a structured form of the heat sink 20 is preferred, which is for example open and / or at least partially closed or completely closed towards its cooling side. Preferably, microchannels are formed in the manufactured heat sink 20, through which a cooling fluid, preferably a cooling liquid, can flow during operation. This allows for dissipation of heat generated, for example, on the component side 4 or caused by a laser diode attached to the connection area 30. To prevent the metallic heat sink 20 from corroding over time, the heat sink 20 at least partially has a corrosion protection layer 30. Otherwise, corrosion would cause the heat sink 20 to leak and / or clog the microchannels or the cooling area.

[0072] 1. Career elements 4. Electrical components 5…Component side 6…Cooling side 7…Web-like element 11...First metal layer 12…Second metal layer 13…Third metal layer 14…Lower cover layer 15…Upper cover layer 21...First part 22...Second part 24...More gaps 25…Fin structure 30…Connection area 33...Transversal Area 34…Rim area 40…Distribution structure 41...Entrance part 42...Exit part 50…Supply structure 70...Metal-ceramic substrate 71...Ceramic elements 72…Component Metallization Section 75…Middle class 73…secondary layer A1…Distance A2…Further distance S…Layer direction T1…First subsection T2…Second subsection Q: Horizontal Q1: First opening cross section Q2: Second opening cross section M…Center axis D…Thickness V: Offset distance RR…Row direction HS1: 1st main flow direction HS2: Second main flow direction HSE…Main extension surface

Claims

1. A carrier substrate (1) for an electrical component (4), comprising: a heat sink (20), a ceramic element (71), at least partially bonded to said heat sink (20), In the manufactured carrier substrate (1), a bonding layer that does not contain a solder material is formed between the heat sink (20) and the ceramic element (71), A carrier substrate (1), wherein the adhesive layer of said bonding layer has a sheet resistance greater than 5 ohms / sq, more preferably greater than 10 ohms / sq, most preferably greater than 20 ohms / sq.

2. The carrier substrate (1) according to claim 1, wherein the ceramic element (71) comprises a material composition which cannot be joined by a direct bonding method.

3. The ceramic element is Si ３ N ４ The carrier substrate (1) according to claim 1 or 2, comprising:

4. The carrier substrate (1) according to any one of claims 1 to 3, wherein the heat sink (20) is bonded to the ceramic element (71) via a back metallization (74), and the adhesive layer is formed between the back metallization (74) and the ceramic element (71).

5. The carrier substrate (1) according to any one of the preceding claims, wherein the grain size of the backside metallization (74) differs from the grain size of the heat sink (20).

6. The carrier substrate (1) according to any one of the preceding claims, wherein the ceramic elements have a thickness of less than 300 μm, more preferably less than 250 μm, most preferably less than 200 μm.

7. 7. The carrier substrate (1) according to any one of claims 1 to 6, wherein the heat sink is formed from at least a first metal layer (21) and a second metal layer (22) bonded onto each other by a direct bonding method, in particular a solderless direct bonding method, the first metal layer (21) and / or the second metal layer (22) having recesses forming cooling channels in the manufactured carrier substrate (1).

8. 8. The carrier substrate (1) according to any one of claims 1 to 7, wherein the thickness of the bonding or adhesive layer, measured in the stacking direction (S) and averaged over a number of measurement points in a given area or within a number of areas running or proceeding parallel to a main extension plane, has a value of less than 1000 nm, more preferably less than 600 nm, most preferably less than 350 nm.

9. A method for producing a carrier substrate (1) according to any one of claims 1 to 8, comprising the steps of: - bonding the backside metallization (74) and preferably the component metallization (72) to the ceramic element (71) by hot isostatic pressing to form a metal-ceramic substrate; - providing a heat sink (20), in particular a heat sink (20) having a cooling channel structure; - bonding said heat sink (20) to said backside metallization (74) by a direct bonding method, in particular the DCB (Direct Copper Bonding) method.

10. voids in the first metal layer (21) and / or the second metal layer (22) are realized by etching, erosion and / or milling, and at least the first metal layer (21) and the second metal layer (22) are bonded together by a DCB process to form the heat sink (20); 10. The method according to any one of claims 1 to 9, wherein the steps of bonding at least the first metal layer (21) and / or the second metal layer (22) to the back metallization and bonding the first metal layer (21) and the second metal layer (22) to form the heat sink (20) are performed at least partially simultaneously.

11. The method according to any one of claims 1 to 10, wherein an active metal layer for forming the bonding layer is disposed between the ceramic element (71) on the one hand and the component metallization (72) and / or the backside metallization (74) on the other hand.

12. 12. The method according to claim 11, wherein the ratio between the thickness of the active metal layer and the thickness of the first metal layer (21) and / or the second metal layer (22) has a value of 0.0001 to 0.005, more preferably 0.005 to 0.003, most preferably 0.001 to 0.0015.

13. The method according to any one of claims 1 to 12, wherein the metal-ceramic substrate (70) is manufactured by hot isostatic pressing, after which the step of bonding the heat sink (20) to the backside metallization (74) is realized.

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