Method for manufacturing a metal semi-finished product, method for manufacturing a metal-ceramic substrate and metal-ceramic substrate

Abstract

The present invention relates to a method for manufacturing a metal semi-finished product (2) for a metal-copper substrate, particularly for a copper-ceramic substrate, the method comprising: - providing a first metal layer (11), particularly a first copper layer, and a second metal layer (12), particularly a second copper layer; - joining the first metal layer (11) and the second metal layer (12) to form the metal semi-finished product (2), wherein, prior to joining the first metal layer (11) and the second metal layer (12), grain growth is induced in the first metal layer (11) and / or the second metal layer (12) by means of different temperature treatments, such that in the finished metal semi-finished product (2), particularly in the finished metal-copper substrate, a first grain size in the first metal layer (11) is different from a second grain size in the second metal layer (12).

Description

[0001] This invention application is a divisional application of the invention patent application filed on November 21, 2018, with application number "201880077483.1" and invention title "Method for manufacturing metal semi-finished products, method for manufacturing metal-ceramic substrates and metal-ceramic substrates". Technical Field

[0002] The present invention relates to a method for manufacturing metal semi-finished products, a method for manufacturing metal-ceramic substrates, and a metal-ceramic substrate. Background Technology

[0003] Metal-ceramic substrates are well known as carriers for electrical or electronic devices. Typically, such metal-ceramic substrates include ceramic layers with metallized portions, wherein the ceramic layer for insulation and the metallized portions for forming connection points and printed wires for electrical or electronic devices are structured. Furthermore, a copper-ceramic substrate is known from DE 10 2015 224 464 A1, wherein the copper layer, i.e., the metallized portion, has a first layer and a second layer, the first layer having an average first grain size and the second layer having an average second grain size, wherein the average first grain size and the average second grain size are different. This design enables the metallized portion in which the copper layer facing the ceramic layer is coarser-grained than the copper layer facing away from the ceramic layer.

[0004] This is advantageous in that the larger grain size on the ceramic layer results in a lower creep limit, leading to improved resistance to temperature changes. Consequently, the likelihood of delamination or cracking during temperature changes is reduced, particularly at the copper-ceramic interface, between the metallized portion and the ceramic layer, or within the ceramic layer parallel to the copper-ceramic interface. Simultaneously, the finer-grained ceramic layer forming the outer edge of the metallized portion is advantageous for further processing via electrical or optoelectronic systems, for the bonding of electrical or electronic devices to the copper layer, and for the overall visual impression.

[0005] To achieve different average grain sizes, a method is proposed in DE 10 2015 224 464 A1, which involves temperature treatment and / or different copper materials, particularly during the bonding method with the copper layer, to induce grain growth. The method should also be constructed more simply and at a lower cost. Summary of the Invention

[0006] Against this backdrop, the present invention is proposed as an object to further improve metal-ceramic substrates or methods for manufacturing them known from the prior art, particularly in setting the first or second particle size as optimally as possible for the application.

[0007] The objective is achieved by a method for manufacturing a metal-ceramic substrate, a method for manufacturing a metal semi-finished product, and a metal-ceramic substrate. Further advantages and features of the invention will become apparent in the specification and drawings.

[0008] According to the present invention, a method is provided for manufacturing metal semi-finished products, particularly copper semi-finished products, for metal-copper substrates, especially for copper-ceramic substrates, the method comprising:

[0009] - Provides a first metal layer, particularly a first copper layer, and a second metal layer, particularly a second copper layer;

[0010] - Connect the first metal layer and the second metal layer to form a metal semi-finished product.

[0011] In this process, before the first metal layer and the second metal layer are joined, grain growth is induced in the first metal layer and / or the second metal layer by means of different temperature treatments, so that in the manufactured metal semi-finished product, especially in the manufactured metal-copper substrate, the first grain size in the first metal layer is different from the second grain size in the second metal layer.

[0012] The method according to the present invention differs from the prior art in that grain growth is induced before the first and second metal layers are joined together, and the first and second grain sizes are adjusted in the subsequently produced metal semi-finished product by means of said grain growth. Through the grain growth induced in the joining preparation stage, the first and second metal layers can be prepared in a simple manner and with individual control for subsequent joining of the first and second metal layers together or for subsequent joining of the metal semi-finished product with a ceramic layer to form a metal-copper substrate.

[0013] In particular, different temperature treatments during the preparation stage of joining allow for the realization of the preconditions for forming a first grain size and a second grain size different from the first grain size, and the first metal layer and the second metal layer can undergo common temperature treatments in the joined state. It is preferably proposed that grain growth prior to joining via temperature treatment is not performed until the desired final first or second grain size is achieved, but rather when joining the first metal layer to the second metal layer or when joining the metal semi-finished product to the ceramic layer. Those skilled in the art will preferably understand the final first or second grain size as the grain size present in the manufactured metal semi-finished product or in the manufactured metal-copper semi-finished product. In particular, it is proposed that grain growth is initiated only in the second metal layer, and the temperature treatment of the first metal layer is to provide the first metal layer at room temperature.

[0014] In principle, it is conceivable to provide an additional second metal layer, which is disposed between the first and second metal layers in the manufactured metal semi-finished product. This additional second metal layer, particularly facing the second metal layer, undergoes a preparatory temperature treatment. Preferably, the manufactured metal semi-finished product composed of the first and second metal layers has a thickness, measured along the layer direction, less than 5 mm, preferably less than 3 mm, and particularly preferably less than 1 mm cm. Furthermore, when the first and second metal layers are joined, the desired ratio between the thickness of the first layer (measured along the layer direction or stacking direction) and the thickness of the second layer (measured along the layer direction or stacking direction) of the first metal layer can be selectively adjusted. Preferably, the first metal layer is thicker than the second metal layer, preferably 1.1 to 15 times thicker, preferably 2 to 10 times thicker, and particularly preferably 3 to 8 times thicker, or the second metal layer is thicker than the first metal layer, preferably 1.1 to 15 times thicker, preferably 2 to 10 times thicker, and particularly preferably 3 to 8 times thicker.

[0015] According to another embodiment of the invention, the first metal layer and the second metal layer are made of the same metallic material. This advantageously allows for the avoidance of compromise in the material selection of the first or second metal layer when connecting the first and second metal layers to form a grain gradient. In particular, the first and second metal layers correspond in terms of their oxygen content or purity. For example, it is conceivable that the first and second metal layers are made of high-purity copper, such as Cu-OFE (Cu ≥ 99.99 wt%). Advantageously, for influencing grain growth, a grain refiner or nucleus is added to the first and / or second metal layers, such that grain growth is confined to the respective metal layer. Preferably, the grain refiner or nucleus is added in a certain amount such that, while affecting grain growth, it does not affect the mechanical and electrical properties of the first and second metal layers. Preferably, the amounts of grain refiner or nuclei are the same, or the amount of grain refiner or nuclei in the first metal layer is 1.5 to 15,000 times, more preferably 2 to 2,000 times, and particularly preferably 4 to 100 times greater than the amount of the agent in the second metal layer used to influence the grain refiner or nuclei. It is also preferred that the amount of grain refiner or nuclei in the second metal layer is less than 1.5% by weight, preferably less than 1.0% by weight, and particularly preferably less than 0.1% by weight. The first or second particle size is particularly understood as the average particle size in the metal of the first or second metal layer.

[0016] In particular, those skilled in the art understand fine microstructure as having a relatively small average particle size, especially a metal layer with an extension or size of less than 100 μm, and coarse microstructure as having a relatively large average particle size, preferably a metal layer with an extension or size greater than 100 μm. It is also preferred that the first average particle size in the first metal layer and the second average particle size in the second metal layer are substantially constant, particularly along directions parallel to and / or perpendicular to the layer direction. This can advantageously be achieved through the uniform distribution of the agent used to influence particle size. However, it is also conceivable that a desired particle size distribution within the first or second metal layer can be achieved by targeted local distribution of the agent used to influence particle size.

[0017] It is suitably proposed that the first average particle size is smaller than the second average particle size. Preferably, the second average particle size is between 160 μm and 2000 μm, more preferably between 200 μm and 1000 μm, and particularly preferably between 250 μm and 500 μm. It is also preferably proposed that the first average particle size is between 50 μm and 200 μm, more preferably between 70 μm and 150 μm, and particularly preferably between 80 μm and 120 μm. The average particle size is here taken as the average value of the particle size distributed along a plane perpendicular to the layer direction.

[0018] In another embodiment of the invention, the second metal layer is thicker than the first metal layer, preferably 1.1 to 15 times thicker, more preferably 2 to 10 times thicker, and particularly preferably 3 to 8 times thicker. This provides a corresponding structural space for the second metal layer, which has a larger first average grain size, whereas, considering the first metal layer, a finer microstructure requires less structural space.

[0019] Preferably, the grain refiner is an alloy metal with relatively high oxygen affinity and minimal edge solubility. This allows the required amount of grain refiner to be kept as small as possible, preventing contamination of the first and second metal layers and making them unsuitable as metallization components in power electronic devices. It has been particularly demonstrated that, in the case of grain refiners B, Ca, Fe, Cr, and zirconium arsenide, at least a few parts per thousand must be added to decisively influence grain growth, such that Cu OFE or Cu PHC is no longer present when copper is used as the metal for the first and second metal layers. Conversely, it has been demonstrated that alloy metals, such as titanium, zirconium, hafnium, chromium, and / or niobium, are suitable in small quantities for forming specific grain sizes at desired dimensions. Preferably, the share of the grain refiner in the first or second metal layer, measured as a weight percentage, is less than 2.5% by weight, preferably less than 1.5% by weight, and particularly preferably less than 1% by weight or even less than 0.5% by weight. For example, the proportion of grain refiner in the first or second metal layer, especially in the case of a first and second metal layer composed of Cu-OFE.

[0020] - For titanium less than 2.1% by weight

[0021] - For zirconium less than 0.17% by weight

[0022] - For hafnium less than 1.1% by weight

[0023] - For chromium less than 0.73% by weight and / or

[0024] - For niobium less than 0.15% by weight

[0025] Together or individually, but preferably each less than 0.01 by weight.

[0026] In another embodiment of the invention, the temperature treatment is an annealing process, wherein preferably, the annealing process for the first metal layer differs from the annealing process for the second metal layer. Specifically, the annealing process involves heating the first and / or second metal layers to a temperature above the recrystallization temperature. Preferably, only the second metal layer undergoes the annealing process. However, it is also conceivable that the annealing processes for the first and second metal layers differ, for example, in terms of duration, temperature control, and / or temperature altitude, thereby achieving different grain growth patterns in the first and second metal layers, respectively.

[0027] Particularly preferred is that the metal layer structure is made of copper, i.e., the first metal layer is a first copper layer and the second metal layer is a second copper layer. It is also conceivable that the metal composition in the first metal layer is different from the metal composition in the second metal layer.

[0028] Preferably, the temperature treatment is performed, at least temporarily, in an inert gas environment or in a vacuum. This advantageously enables defined grain growth during the temperature treatment. This advantageously improves the controlled adjustment of the first or second grain size in the manufactured metal semi-finished product or the manufactured metal-ceramic substrate.

[0029] In another embodiment of the invention, the first metal layer and the second metal layer are joined by means of the DCB method. This advantageously eliminates, for example, the rollers or devices otherwise required for joining the first and second metal layers. Those skilled in the art will understand the “DCB method” (Direct-Copper-Bond-Technology) as a method, for example, for joining metal layers or metal plates (e.g., copper plates or copper films) to each other and / or to ceramic or ceramic layers, more specifically, under the condition of using metal plates or copper plates or metal films or copper films having a layer or coating (molten layer) on its surface side composed of a chemical compound consisting of a metal and a reactive gas, preferably oxygen. For example, in the methods described in US-PS 37 44 120 or DE-PS 23 19 854, the layer or coating (melting layer) forms a eutectic with a melting temperature at the melting temperature of the metal (e.g., copper), such that the layers can be joined together by placing the film on the ceramic and by heating all the layers, or more precisely by melting the metal or copper essentially only in the region of the melting layer or oxide layer.

[0030] In particular, the DCB method has the following steps:

[0031] - Oxidize the copper film to obtain a uniform copper oxide layer;

[0032] - Place the copper film onto the ceramic layer;

[0033] - Heat the composite to a process temperature between, for example, 1025°C and 1083°C, such as to approximately 1071°C;

[0034] - Cool to room temperature.

[0035] Furthermore, it is preferred that the first metal layer and / or the second metal layer be oxidized in time prior to bonding, particularly chemically and / or thermally. Preferably, the oxidation is performed between the temperature treatment and the bonding of the first and second metal layers. Oxidation advantageously provides a eutectic layer in a simple manner, which, for example, allows bonding of the first and second metal layers or the second metal layer to a ceramic layer.

[0036] It is suitably proposed that, in order to limit the second grain size, temperature control be adjusted during the temperature treatment of the second metal layer and / or the second metal layer be coated with a paste layer composed of metal and metal oxides, particularly copper and copper oxide. The advantage of limiting the second grain size is that setting a low oxygen content when bonding to the ceramic layer is not mandatory, in order to counteract thinning of the second metal layer or the formation of cracks in the second metal layer. Such an application of a correspondingly low oxygen content would otherwise be necessary due to the reduced grain boundary area in the second metal layer with increasing grain size and the preferred accumulation of oxygen in the eutectic coating at the metal grain boundaries in the second metal layer. Therefore, by limiting the second grain size, the corresponding adjustment of the oxygen content can be advantageously resisted, thus simplifying the method used for establishing the bond.

[0037] Another aspect of the present invention is a method for manufacturing a metal-ceramic substrate, particularly a copper-ceramic substrate, comprising the following steps:

[0038] - Provides a first metal layer, particularly a first copper layer, and a second metal layer, particularly a second copper layer.

[0039] - Connect the first metal layer and / or the second metal layer to the ceramic layer to form a metal-ceramic substrate.

[0040] In this process, prior to the bonding of the first and second metal layers, grain growth in the first and / or second metal layers is induced by different temperature treatments, resulting in a difference between the first grain size in the first metal layer and the second grain size in the second metal layer in the manufactured metal semi-finished product, particularly in the manufactured metal-copper substrate. All the features and advantages described for the method of manufacturing metal semi-finished products according to the invention are equally applicable to the method of manufacturing metal-ceramic substrates according to the invention.

[0041] In principle, it is conceivable that the first and second metal layers are attached to the ceramic layer as metal semi-finished products, especially as metal semi-finished products manufactured by the method according to the invention, or that the first, second, and ceramic layers are attached to each other in a common connection step, preferably in a common DCB method. As long as the first and second metal layers are attached to the ceramic layer as metal semi-finished products, then, for example, the AMB method or the DCB method can be used. The active solder method, i.e., the "active metalbrazing (AMB)" method, used for attaching metal layers or metal films, especially copper layers or copper films, to ceramic materials, is understood as a method specifically used for manufacturing metal-ceramic substrates. Here, at a temperature between approximately 650°C and 1000°C, a hard solder is used to establish a connection between a metal film, such as a copper film, and a ceramic substrate, such as aluminum nitride ceramic, which, in addition to its main components such as copper, silver, and / or gold, also contains an active metal. For example, the active metal, which is at least one of the elements selected from Hf, Ti, Zr, Nb, and Ce, establishes a connection between the solder and the ceramic through a chemical reaction, and the connection between the solder and the metal is a metal brazing connection.

[0042] Accordingly, the design of the first metal layer, with a smaller average first grain size compared to the second metal layer, prevents the interconnection of electronic devices, especially in fine-wire bonding, from becoming difficult due to excessively coarse microstructure in the first metal layer. Furthermore, the relatively fine microstructure simplifies automated optical inspection (AOI), i.e., inspection of the metal-ceramic substrate after its fabrication. Simultaneously, a grain size gradient is formed along the layer direction during the metal layer structure connection, along which the first and second metal layers are deposited onto the carrier element. Here, this can be understood in the sense of the Hall-Patch relation ( ; where the yield strength R e Initiation stress σ0, grain boundary resistance K, and grain size d k The internal stress present in the metal layer is correlated with the grain size of the structure and is realized in the relatively coarse structure of the second metal layer, thereby advantageously reducing the stress level in the connection region where the second metal layer is connected to the load-bearing element.

[0043] The ceramic forming the ceramic layer can be, for example, Al2O3, Si3N4, AlN, or HPSX ceramics (i.e., ceramics with an Al2O3 matrix comprising x percentage shares of ZrO2, such as Al2O3=HPS9 with 9% ZrO2 or Al2O3=HPS25 with 25% ZrO2). The carrier element preferably has relatively high electrical insulation strength, preferably greater than 5 kV / mm, particularly preferably greater than 10 kV / mm, 20 kV / mm, or even greater than 30 kV / mm, and / or high thermal conductivity, preferably greater than 10 W / mK, particularly preferably greater than 20 W / mK, or even greater than 60 W / mK, such as industrial ceramics or organic insulating materials filled with thermally conductive materials.

[0044] According to another embodiment of the invention, a second metal layer is attached to a ceramic layer in a fabricated metal-ceramic substrate, wherein a second grain size larger than the first grain size is achieved in the second metal layer in the fabricated metal-ceramic substrate by an annealing process prior to attaching the first metal layer to the second metal layer. This advantageously allows for the attachment of a coarser-grained second metal layer to the ceramic layer, while the first metal layer, facing away from the ceramic layer, is finer-grained relative to the second metal layer.

[0045] Another subject of the present invention is a metal-ceramic substrate manufactured by means of the method according to the invention, the metal-ceramic substrate comprising:

[0046] - Ceramic layer, and

[0047] - A composite component consisting of a first metal layer and a second metal layer attached to a ceramic layer, wherein the second particle size in the second metal layer is larger than the first particle size in the first metal layer.

[0048] All the features and advantages described for the method of manufacturing a metal-ceramic substrate according to the present invention can be equally applied to the metal-ceramic substrate according to the present invention. Attached Figure Description

[0049] Other advantages and features will become apparent from the following description of preferred embodiments of the subject matter according to the invention, with reference to the accompanying drawings. The drawings show:

[0050] Figures 1 to 5 The document illustrates method steps for manufacturing a metal-ceramic substrate according to an exemplary embodiment of the present invention; and

[0051] Figure 6 A cross-sectional view of a metal-ceramic substrate according to an exemplary embodiment of the present invention is shown. Detailed Implementation

[0052] exist Figures 1 to 5The diagram illustrates method steps for manufacturing a metal-ceramic substrate 1 according to a first exemplary embodiment of the present invention. This metal-ceramic substrate 1 serves as a carrier for electrical or electronic devices. For conductive connections of the various electrical or electronic devices, metallization portions are provided to form printed wires on the ceramic surface or upper side 15 of the ceramic layer 10. In particular, the metallization portions are structured here to provide printed wires or fixing portions for electronic or electrical devices.

[0053] Advantageously, the metallized portion disposed on the ceramic layer has a first metal layer 11 and a second metal layer 12, wherein a first grain size in the first metal layer 11, i.e., a first average grain size of the metal in the first metal layer 11, differs from a second grain size, i.e., a second average grain size of the metal in the second metal layer 12. In particular, the first metal layer 11 and the second metal layer 12 constitute a composite 2, especially a sandwich structure, for forming the metallized portion on the ceramic layer 10; that is, in the manufactured state, the first metal layer 11 and the second metal layer 12 are overlapped or stacked vertically in a stacking direction S perpendicular to the ceramic surface 15. Figure 6 The diagram shows a metal-ceramic substrate 1, wherein a composite 2 consisting of a first metal layer 11 and a second metal layer 12 is provided on the lower and upper sides. Here, the second metal layer 12 faces the ceramic layer 10 while the first metal layer 11 faces away from the ceramic layer 10, wherein the average first grain size in the first metal layer 11 is smaller than the average second grain size in the second metal layer 12.

[0054] The finer-grained design of the first metal layer 11 compared to the second metal layer 12 advantageously simplifies the connection of electronic or electrical devices on the metallized portion. Furthermore, it provides a visually perceptible uniform or finer overlay for the metallized portion on the ceramic layer 10. It is also advantageously possible to design the connection between the metallized portion and the ceramic layer using a coarser-grained second metal layer 12 compared to the first metal layer 11, such that although the metallized portion and the ceramic layer have different coefficients of thermal expansion, their resistance to temperature changes is optimized. That is, the second grain size is preferably chosen such that the mechanical stress caused by the different coefficients of thermal expansion is kept as small as possible. This advantageously improves the lifespan of the metal-ceramic substrate 1. It is also conceivable that the second grain size approximately corresponds to the second layer thickness D2 of the second metal layer 12. It is also proposed that the second layer thickness D2 is greater than the first layer thickness D1 of the first metal layer 11. For example, it is also possible to consider a first particle size of less than 100 μm, preferably 50 μm, and / or a second particle size of greater than 100 μm, preferably between 250 μm and 1000 μm.

[0055] To specifically control the first or second particle size, and especially the ratio between the first and second particle sizes, a first metal layer 11 and a second metal layer 12 are provided, preferably in the form of a first metal plate and a second metal plate (see...). Figure 1 Here, the first and second metal plates are made of the same metallic material or have the same rules, such as in terms of their oxygen content or purity. For example, the first and second metal layers are Cu-OFE, Cu-OF, or Cu-ETP. Figure 2 As shown, the second metal layer, and especially only the second metal layer, undergoes temperature treatment (see...). Figure 2 The temperature treatment preferably includes an annealing process, wherein the second metal layer is at least temporarily heated to a temperature above the recrystallization temperature. The annealing process advantageously initiates grain growth in the second metal layer and continues until the degree specified by the temperature treatment is reached. Preferably, the annealing process is carried out in an inert gas environment or in a vacuum. Thus, grain growth has at least partially occurred in the second metal layer 12 before the first metal layer 11 and the second metal layer 12 are joined. To achieve the most uniform grain structure possible in the first metal layer 11 and / or the second metal layer 12, a grain refiner or nuclei are incorporated into the first metal layer 11 and / or the second metal layer 12. In particular, the grain refiner or nuclei are selected such that they do not affect the mechanical and electrical properties of the first metal layer and / or the second metal layer except for their effect on grain growth. For example, grain refiners are Cr, Ti, Zr, Hf, and Nb.

[0056] exist Figure 3 In the method steps shown, the first metal layer 11 and the second metal layer 12 are subjected to thermal oxidation and / or chemical oxidation, respectively, so that the eutectic layer required for bonding in the DCB process is composed, in particular, of Cu and O. Preferably, the temperature treatment for initiating grain growth and the temperature treatment for oxidation are coordinated, provided that additional temperature treatment is provided for the oxidation of the second metal layer 12, in order to limit the desired second grain size and avoid giant grain growth. This is because excessively large second grains, due to the reduced area of ​​the grain boundaries, would require a relatively low oxygen content when bonding the second metal layer 12 to the ceramic layer 10, in order to resist thinning or even cracking in the second metal layer 12. Alternatively, a paste consisting of metals and metal oxides, especially Cu and CuO, can be applied to the second metal layer 12 to achieve a eutectic composition without requiring oxidation of the second metal layer 12.

[0057] exist Figure 4 The diagram shows the connection between the first metal layer 11 and the second metal layer 12 used to form the metal semi-finished product 2. Here, the first metal layer 11 and the second metal layer 12 are connected to each other in the DCB process. Figure 5The diagram schematically shows a metal-ceramic substrate 1, in which metal composites 2 are disposed on the upper and lower sides of the ceramic layer, respectively. It is conceivable that the first metal layer 11, the second metal layer 12, and the ceramic layer 10 are connected to each other using a common interconnection method, particularly a common DCB method. Alternatively, it is also conceivable to provide the first metal layer 11 and the second metal layer 21 as... Figure 4 The metal semi-finished product 2 is attached to the copper layer 10 in a separate process step, for example by means of the DCB method or the AMB method.

[0058] List of reference numerals

[0059] 1. Metal-ceramic substrate

[0060] 2 Metal semi-finished products

[0061] 10 ceramic layers

[0062] 11 First metal layer

[0063] 12 Second metal layer

[0064] 15 Ceramic Top Side

[0065] S-stack direction

[0066] D1 First layer thickness

[0067] D2 second layer thickness

[0068] According to embodiments of this disclosure, the following notes are also disclosed:

[0069] 1. A method for manufacturing a metal semi-finished product (2), particularly a copper semi-finished product, for a metal-copper substrate, especially for a copper-ceramic substrate, said method comprising:

[0070] - Provide a first metal layer (11), particularly a first copper layer, and a second metal layer (12), particularly a second copper layer;

[0071] - Connect the first metal layer (11) and the second metal layer (12) to form the metal semi-finished product (2).

[0072] In this process, prior to connecting the first metal layer (11) and the second metal layer (12) in time, grain growth is induced in the first metal layer (11) and / or the second metal layer (12) by means of different temperature treatments, such that in the manufactured metal semi-finished product (2), especially in the manufactured metal-copper substrate, the first grain size in the first metal layer (11) is different from the second grain size in the second metal layer (12).

[0073] 2. According to the method described in Appendix 1,

[0074] The first metal layer (11) and the second metal layer (12) are made of the same metal material, especially copper.

[0075] 3. The method according to any one of the foregoing notes,

[0076] The temperature treatment is an annealing process, and preferably, the annealing process for the first metal layer (11) is different from the annealing process for the second metal layer (12).

[0077] 4. The method according to any one of the foregoing notes,

[0078] The temperature treatment is performed, at least temporarily, in an inert gas environment or in a vacuum.

[0079] 5. The method according to any one of the foregoing notes,

[0080] The first metal layer (11) and the second metal layer (12) are connected by means of the DCB method.

[0081] 6. The method according to any one of the foregoing notes,

[0082] The first metal layer (11) and / or the second metal layer (12) are oxidized prior to the connection.

[0083] 7. The method according to any one of the foregoing notes,

[0084] In order to limit the second particle size, the temperature control during the temperature treatment of the second metal layer (12) is adjusted, and / or the second metal layer (12) is coated with a paste made of metal and / or metal oxide, especially copper and copper oxide.

[0085] 8. A method for manufacturing a metal-ceramic substrate (1), particularly a copper-ceramic substrate, the method comprising the following steps:

[0086] - Provides a first metal layer (11), particularly a first copper layer, and a second metal layer (12), particularly a second copper layer.

[0087] - Connect the first metal layer (11) and / or the second metal layer (12) to the ceramic layer (12) to form the metal-ceramic substrate (1).

[0088] In this process, prior to connecting the first metal layer (1) and the second metal layer, grain growth in the first metal layer (11) and / or the second metal layer (12) is induced by different temperature treatments, such that in the manufactured metal semi-finished product (2), especially in the manufactured metal-copper substrate (1), the first grain size in the first metal layer (11) is different from the second grain size in the second metal layer (12).

[0089] 9. The method according to any one of the foregoing notes,

[0090] The second metal layer (12) is attached to the ceramic layer (10) in the fabricated metal-ceramic substrate (1), wherein a second particle size larger than the first particle size is achieved in the second metal layer (12) in the fabricated metal-ceramic substrate (1) by the annealing process before the first metal layer (11) is attached to the second metal layer (12).

[0091] 10. A metal-ceramic substrate (1) manufactured by means of the method according to Appendix 8 or 9, comprising:

[0092] - Ceramic layer (10), and

[0093] - A composite consisting of a first metal layer (11) and a second metal layer (12) attached to the ceramic layer (10), wherein the second particle size in the second metal layer (12) is larger than the first particle size in the first metal layer (11).

Claims

1. A method for manufacturing a metal-ceramic substrate, the method comprising: - Provide a first metal layer (11) and a second metal layer (12); - Connect the first metal layer (11) and the second metal layer (12) to form a metal semi-finished product (2). In this process, prior to connecting the first metal layer (11) and the second metal layer (12), grain growth in the first metal layer (11) and / or the second metal layer (12) is induced by different temperature treatments, resulting in a first grain size in the first metal layer (11) and a second grain size in the second metal layer (12) of the manufactured metal-ceramic substrate. The metal semi-finished product formed from the first metal layer and the second metal layer is connected to the ceramic layer by active metal brazing, and the final first grain size and the final second grain size are achieved only when the metal semi-finished product and the ceramic layer are connected by active metal brazing. To limit the second grain size, temperature control during the temperature treatment of the second metal layer is adjusted, and / or the second metal layer is coated with a paste layer composed of metal and metal oxides. The connection temperature is set within the range of 650℃ to 1000℃, and In the copper layer, at least one alloying element selected from titanium, zirconium, hafnium, chromium or niobium is provided as a grain refiner.

2. The method according to claim 1, The first metal layer (11) is the first copper layer.

3. The method according to claim 1, The second metal layer (12) is a second copper layer.

4. The method according to any one of claims 1 to 3, The first metal layer (11) and the second metal layer (12) are made of the same metal material.

5. The method according to claim 4, The first metal layer (11) and the second metal layer (12) are made of copper.

6. The method according to any one of claims 1 to 3, The temperature treatment mentioned above is an annealing process.

7. The method according to claim 6, The annealing process used for the first metal layer (11) is different from the annealing process used for the second metal layer (12).

8. The method according to any one of claims 1 to 3, The temperature treatment is performed, at least temporarily, in an inert gas environment or in a vacuum.

9. The method according to any one of claims 1 to 3, The first metal layer (11) and the second metal layer (12) are connected by means of the DCB method.

10. The method according to any one of claims 1 to 3, The first metal layer (11) and / or the second metal layer (12) are oxidized prior to the connection.

11. The method according to any one of claims 1 to 3, The second metal layer (12) is coated with a paste made of copper and copper oxide.

12. The method according to any one of claims 1 to 3, The second metal layer (12) is attached to the ceramic layer (10) in the fabricated metal-ceramic substrate (1), wherein a second particle size larger than the first particle size is achieved in the second metal layer (12) in the fabricated metal-ceramic substrate (1) by the annealing process before the first metal layer (11) is attached to the second metal layer (12).

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