Carrier substrate for electrical components and method for manufacturing such carrier substrate

Abstract

To provide a mounting substrate with high insulation and heat dissipation properties. [Solution] The carrier substrate (1) for the 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 that does not contain solder material is formed between the heat sink (20) and the ceramic element (71). 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 a method for manufacturing such a carrier substrate.

Background Art

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

[0003] To cool a component, a heat sink, which is usually joined to the component, typically has a cooling fluid channel system through which the cooling fluid flows during operation to absorb and remove the heat emitted from the electrical or electronic component. Preferably, a fin structure is used here, in which several bridge-shaped elements protrude into the cooling fluid channel system in order to provide the largest possible contact surface with the cooling fluid, and thus to improve the heat transfer from the wall limiting or protruding into the cooling fluid channel system to the cooling fluid. For example, the heat sink is used to cool a laser diode.

[0004] It is also common to use a heat sink to cool a printed circuit board formed as a metal ceramic substrate.

Summary of the Invention

Problems to be Solved by the Invention

[0005] To insulate electrical components on the component side, insulating elements are typically embedded in a carrier substrate into which a heat sink is integrated, and ceramic elements have proven particularly favorable due to their high insulating strength. However, the selection of materials for ceramic elements used for electrical insulation is limited by the manufacturing process of the carrier substrate, particularly by the bonding of the heat sink, and as a result, the positive thermal properties of, for example, a Si3N4 substrate cannot be utilized for such a carrier substrate.

[0006] Therefore, the present invention aims to provide an improved carrier substrate that can achieve optimized heat dissipation through improved material selection, particularly with respect to ceramic elements. [Means for solving the problem]

[0007] This objective is achieved by the carrier substrate described in claim 1 and the method described in claim 8. Further designs and embodiments can be found in the dependent claims, description and drawings. According to a first aspect of the present invention, - Heatsink and, - A ceramic element, which is at least partially bonded to the heat sink, comprising: In the manufactured carrier substrate, a bonding layer that does not contain solder material is formed between the heat sink and the ceramic element. 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, and most preferably greater than 20 ohms / sq.

[0008] In contrast to carrier substrates known from the prior art having heat sinks and ceramic elements, the present invention provides a solder-free bonding layer formed between the ceramic element and the heat sink, and this bonding layer has relatively high sheet resistance. In other words, the bonding process used for bonding to the ceramic element does not require solder material, and the manufacturing process also results in the generation of relatively high sheet resistance. This is especially true when bonding to the ceramic element is performed by hot isotropic pressurization, more preferably by hot isotropic pressurization 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 relatively thin thickness (dimensioned along the lamination direction) that is uniformly distributed, and this thickness is determined or established in particular by the essentially adhesive layer.

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

[0010] This, along with other parameters such as the purity of the applied active metal layer and / or the roughness of the ceramic element, contributes to the resulting sheet resistance. The advantage of not using solder material when bonding the metal layer to the ceramic element (resulting in the properties described in the claims) is that the temperature required during the heat sink bonding process does not affect the bond between the metal layer and the ceramic element. The heat sink is bonded in a subsequent step after the metal layer has been bonded to the ceramic element, in which the temperature that would remelt the solder material if bonded via solder material prevails. Bonding layers made from solder material, i.e., bonding layers containing solder material, have been shown to have the required sheet resistance, and such bonding layers have been shown to be resistant to the temperatures present when bonding the heat sink to the metal-ceramic substrate. This is advantageous as it makes it possible to provide carrier substrates in which ceramic elements were previously unsuitable because the metal layer could only be bonded via solder systems, particularly solder systems that could not withstand the temperatures required for bonding the heat sink.

[0011] It is emphasized that the described bonding layer is positioned between the heat sink and the ceramic element, and in particular, is formed on the cooling side of the ceramic element or adjacent thereto. It is particularly emphasized that, due to the manufacturing process, at least one metal portion may be formed between the heat sink (in the form provided for bonding) and the ceramic element, or between the installed heat sink and the ceramic element, when viewed in the lamination direction. If this metal portion is made of the same material as the heat sink used in the manufacturing process, a smooth transition may exist between the heat sink and this metal portion. Thus, those skilled in the art will recognize that this metal portion, which is integrally bonded to the heat sink provided in the manufactured state and not due to the heat sink initially used, may be due to the heat sink in the manufactured state, or further metal layers or further metal portions may be formed between the heat sink and the carrier substrate.

[0012] The carrier substrate can be, for example, a printed circuit board, on which conductive paths and / or connection areas are formed on the component side, particularly for forming electrical circuits, for joining electrical components. Alternatively, the carrier substrate could be a cooling system capable of cooling, for example, a laser diode or laser diode device. Preferably, the heat sink is formed by laminating at least first and second metal layers on each other, and the first and second metal layers are joined to each other by a direct bonding method. The corresponding voids in the first and second metal layers can be used to create a cooling channel system through which a cooling fluid, such as a coolant or cooling gas, can flow during operation to dissipate heat from the carrier substrate. For example, the heat sink could be manufactured in a different manner and / or a fin structure could be provided. Regardless of the form of provision, it could be an open or closed cooling structure within the heat sink.

[0013] To determine the sheet resistance, first, the metal layer and, if applicable, the solder base layer are removed from the manufactured carrier substrate, for example, by etching. Next, the sheet resistance is measured by four-point measurement on the upper or lower side of the carrier substrate, freed from at least one metal layer and solder base layer. In particular, the sheet resistance of a material sample should be understood as its resistance to a square surface area. It is customary to characterize surface resistance in units of 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 its manufactured state, with at least one metal layer bonded to a ceramic element and structured. For example, for this purpose, structuring is also performed after the bonding step, for example, by laser processing, etching, and / or mechanical processing, thereby realizing conductive paths and / or connections for electrical or electronic components. Preferably, a further metal layer, in particular a back surface metallization, is provided on the ceramic element opposite the metal layer on the manufactured metal-ceramic substrate. The back surface metallization preferably serves to resist deflection, and a heat sink is bonded to the back surface metallization, serving to effectively dissipate heat generated during operation from the printed circuit board or electrical or electronic components bonded to the metal-ceramic substrate.

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

[0016] Preferably, the thickness of the bonding or adhesive layer, measured in the lamination direction and averaged over multiple measurement points within a given region, or over multiple regions running parallel to or parallel to the main extension plane, has a value of less than 1000 nm, more preferably less than 600 nm, and most preferably less than 350 nm. When the term “multiple regions” is used, it is particularly meant that the metal layer is subdivided into regions of the same size, and at least one value, more preferably several measurements of thickness are recorded in each of these regions subdividing the metal layer. The thicknesses thus determined at different points are arithmetically averaged.

[0017] In particular, ceramic elements have a material composition that cannot be joined by direct bonding methods. Preferably, the ceramic elements contain silicon nitride. In particular, the ceramic elements contain more than 60 weight percent, more preferably 80 weight percent, and most preferably more than 90 weight percent, of silicon nitride. Silicon nitride has been found to be particularly advantageous because it provides high thermal shock resistance and high flexural strength. In addition, the increased coefficient of thermal expansion reduces the formation of thermomechanical stress. Furthermore, the improved thermal conductivity can improve the efficiency of heat dissipation. For hot isotropic pressing used in the manufacture of metal-ceramic substrates, it is found to be particularly advantageous that silicon nitride can also be used in such carrier substrates. Finally, silicon nitride cannot be joined to metal layers, especially copper layers, using direct bonding methods, and the required solder material has a melting temperature of less than 1000°C, so the direct bonding method for heat sinks remelts the solder material. Thus, this method, which is structurally reflected in the solderless bonded layer with increased surface resistance, also enables the use of silicon nitride in the corresponding carrier substrate. Furthermore, preferably, the ceramic element, particularly the silicon nitride ceramic, has a thermal conductivity greater than 90 W / mK, more preferably greater than 110 W / mK, and most preferably greater than 120 W / mK. Furthermore, the ceramic element is considered to have a thickness of less than 300 μm, more preferably less than 250 μm, and most preferably less than 200 μm.

[0018] Alternatively, ceramic elements may be made from Al2O3, AlN, HPSX ceramics (i.e., ceramics having 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), or TSZ (tetragonal stabilized zirconium oxide). It is also conceivable that ceramic elements are formed as compound ceramics or hybrid ceramics, in which case several ceramic layers with different material compositions are placed on top of each other and joined together to form a ceramic element in order to combine various desired properties. Preferably, the ceramic elements do not contain parylene.

[0019] In particular, the heat sink is bonded to the ceramic element via back-side metallization, preferably with an adhesive layer formed between the back-side metallization and the ceramic element. The back-side 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-side metallization has been bonded. As a result, the back-side metallization portion and the heat sink undergo different temperature treatments, which is reflected in different grain sizes. Consequently, these portions can be recognized on the finished substrate.

[0020] Preferably, the grain size in backside metallization differs from the grain size in the heat sink. Backside metallization can also be achieved in the manufacturing process by fixing the metal layer to be bonded within the metal bag during hot isostatic pressing, which results in the metal layer and a portion of the metal bag being bonded together, and thus structural differences can be detected if different pure metal materials are used for the metal layer and the metal bag.

[0021] For example, the bonding layer between the back surface metallization and the ceramic element may contain an active metal content derived from the active metal layer used in the manufacturing process. Furthermore, the back surface metallization may protrude along the main extension surface relative to the heatsink. The heatsink is bonded to the back surface metallization already bonded to the ceramic element, and preferably does not extend across the entire back surface of the ceramic element, thus allowing for a larger back surface metallization. This means that the back surface metallization, preferably bonded to the ceramic element across the entire surface, does not need to be partially removed again. This also simplifies the positioning of the heatsink relative to the back surface metallization during manufacturing, as it does not need 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 bonded to each other by a direct bonding method, particularly a solderless direct bonding method, wherein the first metal layer and / or the second metal layer have recesses that form a cooling channel within the manufactured carrier substrate. It is also conceivable that the cooling channel extends to a ceramic element, and / or a residual metal layer thickness is provided between the ceramic element and the cooling channel, almost exclusively, more preferably without exception. In order to form a cooling channel that extends to the carrier substrate or ceramic element, in the manufacturing process, after the back surface metallization is bonded to the ceramic element, and before the bonding process to the back surface metallization of the heat sink is performed, the back surface metallization is structured to expose the corresponding area on the ceramic element.

[0023] Preferably, the distance between the sides defining the cooling channel is less than 0.5 mm, more preferably less than 0.4 mm, and most preferably less than 0.3 mm. In particular, this refers to sides spaced apart in a direction parallel to the main extension plane. Such relatively thin channels and distances between sides can be created, for example, by erosion or wire cutting in each metal layer. Such thin cooling channels are found to be particularly advantageous because they can ensure high efficiency in heat transfer and also provide particularly uniform and homogeneous distributed cooling or heat transfer on the cooling side.

[0024] Preferably, the thickness of the bonding layer or the adhesive layer, measured in the stacking direction and averaged over a plurality of measurement points within a predetermined region or within a plurality of regions proceeding or running parallel to the major extension plane, has a value of less than 1000 nm, more preferably less than 600 nm, and most preferably less than 350 nm. When the term "a plurality of regions" is used, in particular, the metal layer is subdivided into regions of as equal size as possible, and at least one value for the thickness, more preferably several measured values, is recorded in each of these regions subdividing at least one metal layer. The thicknesses determined in this way at different points are arithmetically averaged.

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

[0026] In particular, the adhesive layer containing an active metal has a substantially constant thickness. In particular, the measured values of the thickness determined within 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, and most preferably less than 0.05 μm is assigned. In particular, the physical and / or chemical vapor deposition of the active metal layer and the resulting bonding layer makes it possible to achieve a homogeneous and uniformly distributed thickness of the bonding layer consisting only of the adhesive layer. Also, the adhesive layer can have a constant thickness when formed in addition to the solder base material.

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

[0028] All the advantages and characteristics of the carrier substrate described can be similarly applied to and adapted to this method, and vice versa. Preferably, during hot isotropic pressurization, the metal container or metal layer is subjected to a gas pressure of 100-2000 bar (10-200 MPa), more preferably 150-1200 bar (15-120 MPa), most preferably 300-1000 bar (30-100 MPa), and a processing temperature from 300°C to the melting temperature of the metal layer, particularly below the melting temperature. Advantageously, it has been shown that metal layers, such as component metallization and / or back-surface metallization, can be bonded to ceramic elements without the required temperatures of direct metal bonding processes, such as DCB or DAB processes, and without solder base material or solder material used for active soldering. In addition, the use or application of appropriate gas pressure makes it possible to manufacture metal-ceramic substrates that are as void-free as possible, i.e., free of gas inclusions between the metal layer and the ceramic element. In particular, the process parameters mentioned in German Patent Application Publication No. 2013113734 are used, and these process parameters are expressly referenced herein. The bond between the ceramic element and the metal layer manufactured in this way has also been shown to withstand temperatures exceeding 1050°C.

[0029] In particular, the method of the present invention is characterized by the fact that the bonding of the back surface metallization to the ceramic element is performed as part of a hot isotropic pressurization process, rather than as part of a soldering process. This makes the bonding between the component metallization or back surface metallization on one side and the ceramic element on the other side more durable, in particular with respect to the temperature used when bonding the heat sink to a metal-ceramic substrate. In particular, the heat sink is bonded to the back surface metallization of a metal-ceramic substrate manufactured by hot isotropic pressurization. As a result, there is no need to rely on a solder-based bonding method to use ceramic elements that cannot be bonded to the metal layer by direct bonding methods. Thus, the described method also enables the bonding of such ceramic elements that could not have been previously used to form the described carrier substrate, since the solder material used may be damaged or even destroyed during the heat sink bonding process.

[0030] Preferably, voids within the first or second metal layer are realized by etching, erosion, and / or milling, bonding at least the first and second metal layers together to form a heat sink. This provides a heat sink for bonding, and the corresponding heat sink provides a cooling channel system that can guide a cooling fluid to dissipate heat within the manufactured carrier substrate.

[0031] Preferably, an activated metal layer is positioned between the ceramic element and the component metallization or back-side metallization on the other side. This provides a particularly strong bond between the back-side metallization and the ceramic element during hot isotropic pressurization, and the activated metal layer significantly contributes to the formation of an adhesive layer or bonding layer. In particular, the activated metal layer becomes an adhesive layer, especially 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, and thus achieve a relatively thin thickness of the bonding layer as claimed, averaged over different measurements within one or more defined regions. 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 are readily oxidized. Although the elements Cr, Mo, and W are not classical active metals, it should also be noted that they are suitable as contact layers between Si3N4 and at least one metal layer or solder system or solder material, as they do not form an intermetallic phase with at least one metal layer, e.g., copper, and do not have solid solution properties.

[0033] Preferably, the active metal is deposited on the solder base material and / or at least one metal layer and / or ceramic element by physical and / or chemical deposition, for example by sputtering, to create a relatively thin active metal layer, which then results in a relatively thin bonding layer, particularly a homogeneous and thin adhesive layer. It is also conceivable to provide the active metal layer on the ceramic element and / or the metal layer for component metallization and / or back surface metallization by plasma, in a vacuum, and / or by 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 formed, in particular, by gas physical deposition, thus enabling the realization of a relatively thin active metal layer, which can also contribute to achieving the required surface resistance. Galvanic deposition, electroless deposition, and / or thermal deposition, or deposition by cold gas spray are also possible.

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

[0036] Preferably, bonding of the heat sink to the back surface metallization is achieved by hot isotropic pressing after the metal-ceramic substrate is formed. The metal-ceramic substrate is formed first to ensure that bending due to thermomechanical stress within the metal-ceramic substrate is prevented during the formation process of the metal-ceramic substrate by ensuring that the thickness of the back surface metallization and the component metallization are as equal or equivalent as possible. In other words, the metal-ceramic substrate with component metallization and back surface 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. In this case, it becomes 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 metal layers greater than 0.4 mm bonded to ceramic elements cause greater thermomechanical stress after cooling, which also persists after cooling.

[0037] Further advantages and characteristics are derived from the following description of preferred embodiments of the subject matter according to the present invention, with reference to the accompanying drawings. These are shown below. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic diagram of a carrier substrate according to an exemplary embodiment of the present invention. [Figure 2] This is a schematic exploded view of a carrier substrate according to an exemplary embodiment of the present invention. [Figure 3] Figure 1 is a schematic diagram of the first metal layer for the heat sink. [Figure 4] This is a schematic diagram of a carrier substrate according to a further exemplary embodiment of the present invention. [Figure 5] This is a detailed diagram of a system equipped with a carrier substrate having a distribution structure. [Figure 6] This is a detailed diagram of a system equipped with a carrier substrate having a distribution structure. [Figure 7] This is a detailed diagram of a system equipped with a carrier substrate having a distribution structure. [Figure 8] This is a detailed diagram of a system equipped with a carrier substrate having a distribution structure. [Modes for carrying out the invention]

[0039] Figure 1 schematically shows a carrier substrate 1 according to a preferred embodiment of the present invention. Such a carrier substrate 1 is provided, in particular, to enable electrical components 4 to be joined on their component side 5. For example, the carrier substrate 1 may be a printed circuit board having a plurality of connection areas, 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 includes a heat sink 20. This heat sink 20 is formed on the cooling side 6 opposite to the component side 5. Preferably, the heat sink 20 is a metal structure formed by laminating at least a first metal layer 21 and a second metal layer 22 on each other, and then bonding at least one metal layer 21 and the second metal layer 22. Recesses embedded in the first metal layer 21 and / or the second metal layer 22 make it possible to realize a channel system within the heat sink 20. A cooling fluid, such as a cooling gas or coolant, may be guided through this channel system to adequately dissipate heat from the carrier substrate 1. To particularly insulate the electrical components 4 from the metal heat sink 20, the carrier substrate 1 includes a ceramic element 71. Preferably, the carrier substrate 1 has a metal-ceramic substrate 70 and a heat sink 20, which are coupled together to form the carrier substrate 1. Preferably, the metal-ceramic substrate 70 provides component metallization 72 on the component side of the ceramic element 71 and backside metallization 74 on the cooling side 6 of the ceramic element 71 on the opposite side 5 of the metal-ceramic substrate 70. The thicknesses of the component metallization 72 and backside metallization 74 correspond to each other, particularly in the manufacturing step where the component metallization 72 and backside metallization 74 are bonded to the component side of the ceramic element 71, in order to compensate for the thermomechanical stress caused by the different thermal expansion coefficients of the backside metallization 74 / component metallization 72 on one side and the ceramic element 71 on the other side. Without such compensation, the metal-ceramic substrate 70 would tend to flex.Therefore, it is preferable that the heat sink 20 is bonded to the metal-ceramic substrate 70, and in particular to the back surface metallization 74 of an already manufactured metal-ceramic substrate 71. The bonding of the cover layer of the heat sink 20 to the back surface metallization 74 is preferably carried out by a direct bonding method, particularly a solderless direct bonding method, which requires a temperature exceeding 1068°C to generate a eutectic formed between the back surface 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, 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 back surface metallization 74 may be performed simultaneously or at least in overlapping time. The first metal layer 21 may form a cover layer (see embodiment in Figure 1), and / or the cover layer may be an additional layer bonded to the upper side of the heat sink 20. For example, the cover layer may form a continuous metal layer without voids.

[0041] The need to bond the heat sink 20 to the metal-ceramic substrate 1, particularly to the back surface 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 surface metallization 74 must also withstand the manufacturing conditions required to bond 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, will loosen or at least impair the bond between the back surface metallization 74 or component metallization 72 and the ceramic element 71. This is especially true when a solder material with a melting temperature of less than 1000°C must be used to bond the component metallization 72 or back surface metallization 74 to the ceramic element 71.

[0042] However, this also has the consequence that such ceramic elements 71 can only be bonded to a metal layer (i.e., component metallization 72 or back-side metallization 74) via solder material, thus being excluded from use in the carrier substrate 1 described. This applies, for example, to silicon nitride, which cannot be bonded to metal using direct bonding methods. In order to use such ceramic elements, which would otherwise need to be excluded, in the carrier substrate described above, the present invention provides a solderless bonding process, particularly solderless hot isotropic pressing, for bonding component metallization or back-side metallization to the ceramic elements 71.

[0043] In particular, as part of the bonding process, an active metal layer is placed between the ceramic element 71 and the component metallization 72, and / or between the ceramic element 71 and the back surface metallization 74, during hot isotropic pressurization. This is deposited, for example, before hot isotropic pressurization, on the component side 5 or cooling side 6 of the ceramic element 71, and / or on the component metallization 72 and / or back surface metallization 74, for example, by gas physical deposition, for example, by a sputtering process, or by an electrochemical method. Bonding between the ceramic element 71 and the component metallization 72 or back surface metallization 74 is possible, and it has been found to be possible in particular for ceramic elements 71 that are inaccessible by direct metal bonding processes. At the same time, it has been found that the bonding can withstand the temperatures required for the direct bonding method of the heat sink 20 to the metal-ceramic substrate 70. This is due in particular to the fact that bonding between the ceramic element and the metal layer can be performed in this case without solder material or solder base material.

[0044] It is emphasized again that the active metal layer is an active metal layer in which the proportion of active metal is greater than 15 weight percent, more preferably greater than 30 weight percent, and most preferably greater than 70 weight percent. Therefore, it is not an active metal-containing solder layer as is typical when bonding the component metallization 72 to the ceramic element 71. This makes it possible to use a ceramic element 71 that is particularly preferred, for example, for high thermal conductivity or advantageous for forming the corresponding carrier substrate 1. This is especially true for carrier substrates 1 in which the ceramic element 71 contains silicon nitride or is formed from more than 80% silicon nitride.

[0045] The described joining method preferably involves a joining layer, -The bonded layer is characterized by having a bonding layer between the ceramic element 71 and the component metallization portion 72, and / or between the ceramic element 71 and the back surface metallization 74, and its sheet resistance is greater than 5 ohms / sq, more preferably greater than 15 ohms / sq, and most preferably greater than 20 ohms / sq. The described sheet resistance is a result of bonding by uniformly applied active metal layer and hot isotropic pressurization. In contrast, a bonding layer manufactured using a solder material having an active metal component has a lower sheet resistance. In particular, if only an adhesive layer is formed as a bonding layer between the back surface metallization 74 or component metallization 72 and the ceramic element 71, i.e., sub-regions attributable to the solder material cannot be identified in the manufactured carrier substrate 1.

[0046] The bonding process of the back surface metallization 74 to the cover layer of the heat sink 20 as part of the direct bonding method means that the boundary / transition region cannot be identified in the manufactured transition between the back surface metallization 74 and the upper side of the heat sink 20, so that the back surface metallization 74 is part of the heat sink 20 in the manufactured state. Thus, a sheet resistance is formed between the ceramic element 71 and the heat sink 20, and the original back surface metallization 74 of the metal-ceramic substrate 1 is added to it in the manufactured state. Thus, a metal-ceramic substrate manufactured according to the method of the present invention can 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 that is formed solely as an adhesive layer and not due to solder material.

[0047] Furthermore, a meandering or loop-shaped channel system is formed in Figure 1, into which, for example, a cooling fluid can be introduced through an inlet E, and the cooling fluid is guided through the heat sink 20 in a loop- or meandering motion, and finally exits the heat sink 20 again through an outlet opening A. Further examples of heat sinks that can be provided for specific embodiments of the present invention and that can be bonded to a metal-ceramic substrate 70, in particular to its back surface metallization, are given in the following figures.

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

[0049] For this purpose, the supply and discharge regions are preferably provided within the heat sink 1, particularly within a cooling fluid channel system (not shown), where the cooling fluid is introduced through the supply region and discharged again through the discharge region. Preferably, the cooling fluid channel system is provided such that the cooling fluid 1 passes through a fin structure 25 during the transition from the supply region to the discharge region, and the fin structure 25 particularly protrudes into the cooling fluid channel system. The fin structure 25 is preferably a web-like element 7, which protrudes into the cooling fluid channel system to provide the largest possible contact surface with the fluid, and allows for effective heat transfer from the web-like element 7 or the walls 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 a 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 by at least one void 21, 22 so as to form a cooling fluid channel system by stacking one on top of the other along the stacking direction S, or by placing one on top of the other.

[0051] In particular, at least one first metal layer 11, at least one second metal layer 12, and / or at least one third metal layer 13 are each structured in a different way or provided with voids 21, 22 of different paths. Specifically, at least one first metal layer 11, at least one second metal layer 12, and / or at least one third metal layer 13 form at least one first portion 21 within at least one void 21, 22, the first portion 21 having a web-like element 7 extending in a main extension plane HSE that extends particularly perpendicular to the lamination direction S. In addition to the first portion 21 of at least one void 21, 22 within at least one first metal layer 11, it is preferable that the second portion 22 of at least one void 21, 22 within 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 the supply area and / or discharge area.

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

[0053] Figure 3 shows a schematic diagram of at least one first metal layer 11 installed, for example, in Figure 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 toward the central axis M of at least one first metal layer 11. As a result, it is advantageously possible to maximize the cooling effect, particularly in the central region of the connection area 30. Furthermore, the web-like elements may extend parallel to 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 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 electrical or electronic components.

[0054] 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 within at least one first metal layer 11 is produced by erosion, particularly spark erosion. In particular, this includes production by wire erosion.

[0055] Furthermore, a second portion 22 of at least one void 21, 22 is performed by etching. Preferably, etching is performed particularly in large area regions of the second portion 22 of the void 21, 22, i.e., in subsequent supply and / or discharge regions formed for supplying and discharging cooling fluid. In contrast, erosion is provided in particular for microstructuring of the void 21, 22, i.e., the first portion 21 of the void 21, 22. This has been found to make it possible to produce a relatively small distance between the web-like elements 7 without having to rely on several first metal layers 11 having etched first portions 21 of at least one void 21, 22, which must be laminated 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 the two web-like elements 7 is less than 0.4 mm, more preferably less than 0.3 mm, and 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. Therefore, the contact surface between the cooling fluid and the wall of the cooling fluid channel system can be appropriately increased, thereby increasing the cooling effect.

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

[0057] Furthermore, the upper cover layer 15 and / or the lower cover layer 14 each have at least one void 21, 22 and / or further voids 24, and the upper cover layer 15 and / or the lower cover layer 14 preferably do not include any web-like elements 7 or any later fin structure 25 components. The further voids 24 are preferably used to mount or secure the heat sink 1.

[0058] Figure 4 schematically shows a metal-ceramic substrate 70 according to a further exemplary embodiment of the present invention. Such a metal-ceramic substrate 1 preferably functions as a carrier for an electronic or electrical component 4 that can be connected to the metal-ceramic substrate 70. 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 portion 72 bonded to the ceramic layer 71. The ceramic element 71 is made from at least one material including ceramic. The component metallization portion 72 and the ceramic element are arranged on top of each other along a lamination direction S extending perpendicular to the main extension plane HSE and are bonded to each other by material bonding. In the manufactured state, the component metallization portion 72 is structured on the component side 5 of the metal-ceramic substrate 70 to form a conductor path or connection point for the electrical component 4. In the illustrated embodiment, the metal-ceramic substrate 70 comprises a secondary layer 73 and a metal intermediate layer 75 positioned 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 lamination 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 1.5 mm, and most preferably 2.5 mm. However, it is also conceivable that only the ceramic element 71 having component metallization 72 and back surface metallization is formed to form a metal-ceramic substrate. The ceramic element 71 is preferably made of ceramic and is designed to form sufficient insulating strength and reinforce the metal-ceramic substrate 1, while the secondary layer 73 may be made of, for example, tungsten or molybdenum, as significant insulating strength is not required here. This reduces material costs. Alternatively, the secondary layer 73 may also be made of a ceramic-containing material.

[0059] The metal heatsink 20 is provided on the cooling side 6 of the metal-ceramic substrate 1 opposite the component side 5. Preferably, the metal heatsink 20 is directly bonded to the secondary layer 73. However, it is also conceivable that the heatsink 20 be directly bonded to the back surface metallization of the metal-ceramic substrate 1, or to the ceramic elements 71 of the metal-ceramic substrate 1. This makes it possible to avoid the interface formed between the heatsink and the corresponding connecting material, which would otherwise adversely affect thermal conductivity and thus limit 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, back surface metallization, and / or ceramic element 71 by the AMB method, DCB (direct copper bonding) method, or DAB (direct aluminum bonding) method. In particular, multiple fluid channels 30 are integrated into the metal cooling structure 20. For clarity, only one of these fluid channels 30 is shown as an example in Figure 1. The fluid channels 30 serve to guide the fluid, in particular the cooling fluid, within the metal cooling structure 20. The fluid is supplied to the cooling structure 20 via a distribution structure 40 and discharged again via the distribution structure 40. Preferably, the distribution structure 40 has an inlet portion 41 and an outlet portion 42 for this purpose.

[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 the outer surface A of the cooling structure 20 facing the distribution structure 40. Specifically, 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 into which they are embedded. Furthermore, in view in the stacking direction S, the supply structure 50 is adjacent to the lower side of the distribution structure 40. Thus, in view in the stacking direction S, the distribution structure is positioned between the cooling structure and the supply structure. Such a supply structure 50 is preferably provided to predetermine 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 section and a cooling fluid discharge section. The distribution structure 40 is preferably designed to divert fluid into or introduce fluid into the cooling structure 20 from the flow flowing along the first main flow direction HS1. For further clarification, the figure shows only a single row of fluid channels 30. Preferably, multiple rows are arranged adjacent to each other or in sequence in a direction perpendicular to the row direction RR and parallel to the main extension plane HSE, and each of these rows is supplied with fluid through a corresponding distribution structure 40, for example, a single distribution structure. Preferably, these multiple rows extend entirely through the outside A of the cooling structure 20 facing the distribution structures.

[0063] In particular, several fluid channels 30 are arranged adjacent to one another. Specifically, in the illustrated embodiment, the fluid channels 30 are arranged along a row that extends essentially perpendicular to the first main flow direction HS1 in the illustrated embodiment. Basically, the row may also extend along a row direction RR inclined at an angle of 0 to 90° with respect to the first main flow direction HS1. Preferably, this angle is less than 45°.

[0064] In the embodiments shown in Figures 4 to 8, the distribution structure 40 deflects the fluid such that at least a portion of the fluid is first deflected in a lateral direction Q extending parallel to the column direction from the first main flow direction HS1 before being directed toward the inlet opening 31. In addition, the fluid is deflected toward the cooling structure 20, i.e., upward toward the inlet opening 31. As a result, the distribution structure can supply fluid of the same temperature to several inlet openings 31 of different fluid channels 30. For this purpose, the inlet portion 41 is designed as a wall-like structure extending essentially parallel to the column direction RR in the illustrated embodiments. Preferably, the supply structure 50 supplies fluid to only a portion of the distribution structure 40. In the illustrated embodiments, viewed along the first main flow direction HS1, essentially a first portion of the inlet portion 41, particularly the left half, is flowed by the cooling fluid. However, the entire column of fluid channels 30 is supplied with fluid by the distribution structure 40. Preferably, the inlet portion includes a ramp-like structure inclined when viewed in the column direction RR, particularly inclined with respect to the main extension plane HSE.

[0065] After passing through the fluid channel 30, the fluid exits the cooling structure 20 through the outlet opening 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 exiting the outlet opening and divert it in a second main flow direction HS2 to return it to the supply structure 50. For example, the outlet portion 42 includes a ramp-like structure inclined in the column direction RR, in particular 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 exiting the distribution structure 40, the fluid flow is offset laterally or perpendicularly with respect to the flow when it was flowing toward the distribution structure 40.

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

[0067] Each fluid channel 30 is preferably U-shaped, and the U-shaped fluid channel 30 has two rim regions 34 extending substantially perpendicular to the main extension plane HSE and a transverse region 33 connecting the two rim regions 34. In particular, the transverse region 33 plays a role in deflecting 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 is 0.2 to 1.5 mm, more preferably 0.4 to 1 mm, and most preferably 0.6 mm to 0.8 mm. Preferably, the fluid channels 30, and especially their rim regions 34, are designed so that the fluid swirls within the fluid channels 30. For this purpose, for example, the opening cross sections Q1, Q2 of the rim regions 34 that advance parallel to the main extension plane HSE are displaced laterally along the direction of fluid flow within the fluid channels 30, and especially within the rim regions 34. The rim region 34 comprises a first subsection T1 having a first opening cross-section Q1 and a second subsection T2 having a second opening cross-section Q2, wherein the first opening cross-section Q1 is 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 the same size. However, it is also possible that the first opening cross-section is different from the second opening cross-section. In particular, the first subsection T1 and the second subsection T2 are each assigned to metal layers that are laminated on each other, for example, during manufacturing. The individual metal layers may be the same thickness or of different thicknesses. For example, the thickness of the individual layers may decrease and / or increase in the direction toward the part.

[0068] In particular, the first opening cross section Q1 and the second opening cross section Q2 are offset from each other in two directions that are not parallel 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 column direction RR. Preferably, the ratio of the overlapping region in which the first opening cross section Q1 and the second opening cross section Q2 are positioned on top of each other when viewed in the stacking direction S, to the first opening cross section Q1 or the second opening cross section Q2, is 0.5 to 0.9, more preferably 0.5 to 0.8, and most preferably 0.5 to 0.7. In particular, the opening cross sections of the inlet opening and / or outlet opening may be larger than those of the first opening cross section and / or the second opening cross section. This allows funnel-shaped inlet and outlet regions to be formed for the fluid channel.

[0069] However, the first opening cross section Q1 and the second opening cross section Q2 may be 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 laminating metal layers having corresponding openings, i.e., at least a first metal layer 11 and a second metal layer 12, or by a 3D printing process. Furthermore, the inlet opening 13 has a first opening cross section, and its diameter and / or edge length has a value of 0.1 mm to 2.5 mm, more preferably 0.5 mm to 1.5 mm, most preferably essentially 1 mm. Preferably, the first opening cross section Q1 or the second opening cross section Q2 does not change within the rim region 34 of the fluid channel 30.

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

[0071] In addition to the heat sink 20 or carrier substrate 1 described above, other heat sinks 20 having different geometric shapes are also conceivable. For example, the heat sink 20 may be 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 to its cooling side and / or at least partially closed, or completely closed. Preferably, microchannels are formed within the manufactured heat sink 20, through which a cooling fluid, preferably a coolant, can flow during operation. This allows for the dissipation of heat generated, for example, on the component side 4, or heat caused by a laser diode attached to the connection region 30. To prevent the metal heat sink 20 from corroding over time, the heat sink 20 has at least a partially corrosion-resistant layer 30. Otherwise, corrosion would cause leakage in the heat sink 20 and / or clog the microchannels or cooling regions.

[0072] 1…Career elements 4… Electrical components 5…Component side 6…Cooling side 7…Web-like elements 11…First metal layer 12…Second metal layer 13…Third metallic layer 14…Lower cover layer 15…Upper cover layer 21... Part 1 22... Part 2 24… Further gaps 25…Fin structure 30…Connection area 33…Cross-sectional area 34…Rim area 40…Distribution structure 41...Entrance part 42...Exit part 50…Supply structure 70…Metal-ceramic substrate 71…Ceramic elements 72... Parts Metallization Section 75…Middle class 73…secondary layer A1... Distance A2... Further distance S...Stacking direction T1…First subsection T2…Second subsection Q...Horizontal direction Q1…First opening cross section Q2…Second opening cross section M…Center axis D...thickness V...Offset distance RR…Row direction HS1…First main flow direction HS2…Second main flow direction HSE…Main extension surface

Claims

1. A carrier board (1) for an electrical component (4), - Heat sink (20), - A ceramic element (71) which is at least partially bonded to the heat sink (20), comprising: In the manufactured carrier substrate (1), a bonding layer that does not contain solder material is formed between the heat sink (20) and the ceramic element (71). The adhesive layer of the bonding layer has a sheet resistance greater than 5 ohms / sq in the carrier substrate (1), The heat sink (20) is bonded to the ceramic element (71) via back surface metallization (74), and the adhesive layer is formed between the back surface metallization (74) and the ceramic element (71). A carrier substrate (1) wherein the ceramic element (71) has a material composition that cannot be joined by a direct bonding method.

2. The aforementioned ceramic element is Si ３ N ４ A carrier substrate (1) according to claim 1, including the above.

3. The carrier substrate (1) according to claim 1, wherein the grain size of the back surface metallization (74) is different from the grain size of the heat sink (20).

4. The carrier substrate (1) according to claim 1, wherein the ceramic element has a thickness of less than 300 μm.

5. The carrier substrate (1) according to claim 1, wherein the heat sink is formed from at least a first metal layer (21) and a second metal layer (22) bonded to each other by a direct bonding method, and the first metal layer (21) and / or the second metal layer (22) have recesses that form cooling channels within the manufactured carrier substrate (1).

6. The carrier substrate (1) according to claim 1, wherein the thickness of the bonding layer or adhesive layer, measured in the stacking direction (S) and averaged over a plurality of measurement points within a predetermined region, or over a plurality of regions that advance or run parallel to the main extension plane, has a value of less than 1000 nm.

7. A method for manufacturing a carrier substrate (1) according to any one of claims 1 to 6, - A step of bonding the back surface metallization (74) to the ceramic element (71) by hot isotropic pressure in order to form a metal-ceramic substrate, - The step of providing a heat sink (20), A method comprising the step of joining the heat sink (20) to the back surface metallization (74) by a direct bonding method.

8. The voids within 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 to each other by a DCB (direct copper bonding) process to form the heat sink (20). The method according to claim 7, wherein the steps of joining at least the first metal layer (21) and / or the second metal layer (22) to the back surface metallization and joining the first metal layer (21) and the second metal layer (22) to form the heat sink (20) are performed at least partially simultaneously.

9. The method according to claim 7, wherein the activated metal layer for forming the bonding layer is disposed between the ceramic element (71) on one side and the component metallization (72) and / or the back surface metallization (74) on the other side.

10. At least the first metal layer (21) and the second metal layer (22) are joined to each other by a direct bonding method to form the heat sink (20). The method according to claim 9, wherein the ratio between the thickness of the activated metal layer and the thickness of the first metal layer (21) and / or the second metal layer (22) is a value of 0.0001 to 0.

005.

11. The method according to claim 7, wherein the metal ceramic substrate (70) is manufactured by hot isotropic pressurization, and the step of bonding the heat sink (20) to the back surface metallization (74) is then realized.

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