Multilayer component and method for manufacturing a multilayer component

Abstract

Multilayer component (1) comprising a ceramic base body (2) and at least one metal structure (3, 5, 6), wherein - the metal structure (3, 5, 6) is co-sintered, - the base body (2) is a varistor ceramic sintered with liquid phases and has the following composition: - ≥ 95 % Mol ZnO, - from 0.5 to 5% mol Sb2O3, - from 0.05 to 2% mol CO3O4, Mn2O3, SiO2 and / or Cr2O3, - < 0.1 % mol B2O3, Al2O3 and / or NiO, - the metal structure (3, 5, 6) has silver and / or palladium and, - the ceramic base body (2) has a doping with material of the metal structure (3, 5, 6).

Description

[0001] The present patent application relates to an electrical multilayer component and a method for manufacturing a multilayer component.

[0002] Multilayer devices based on zinc oxide are commonly known as varistors. For the electrical contacting of multilayer varistors, expensive internal electrodes made of silver and palladium (Ag, Pd) are typically used.

[0003] Internal electrodes made of a silver-palladium alloy are frequently used to reduce diffusion of the electrode material into the ceramic material during the sintering process, as described, for example, in US document 4,675,644A. The addition of palladium appropriately raises the melting point of the electrode layers, allowing the electrode layer to be sintered together with the ceramic and reducing silver diffusion during sintering. However, the addition of palladium has the disadvantage of being very expensive.

[0004] Furthermore, varistors are known, for example, from document US 4,959,262 A, where the reduction of the electrode layer during the sintering process is addressed by using larger layer thicknesses of up to 10 µm. These thicker electrode layers have the disadvantage that—due to the different sintering behavior of the materials—delamination occurs more frequently. In addition, thicker internal electrodes require more volume, which proves problematic for very small components.

[0005] DE 100 38 425 A1 discloses a semiconductor ceramic device with positive thermal resistance properties based on barium titanate.

[0006] US 2012 / 0 135 563 A1 reveals a manufacturing process for a multilayer varistor.

[0007] DE 10 2005 026 731 A1 discloses a multilayer chip varistor with a varistor section and two outer layer sections enclosing the varistor section.

[0008] EP 0 029 749 A1 discloses a voltage-dependent resistor with a sintered base body and a method for manufacturing the resistor.

[0009] US 6 260 258 B1 discloses a method for manufacturing a varistor.

[0010] DE 11 2005 001 527 T5 discloses an electrically conductive paste comprising an electrically conductive powder of base metal, a first glass frit and an organic binder.

[0011] One task to be solved is to specify a multilayer component with improved properties and a method for manufacturing an improved multilayer component.

[0012] The invention for solving this problem is defined by independent claim 1 and by dependent claim 15. Advantageous embodiments of components and manufacturing methods are specified in the associated dependent claims.

[0013] A multilayer component is described according to one aspect. The multilayer component, or component for short, has a ceramic substrate. The substrate is a varistor ceramic. The substrate is a zinc oxide (ZnO) varistor. The substrate consists of approximately 95 mol% ZnO. The substrate also contains Sb₂O₃ in the range of 0.5 to 5 mol%. Furthermore, the substrate contains CO₃O₄, Mn₂O₃, SiO₂, and Cr₂O₃ in the range of 0.05 to 2 mol%, for example, 0.5 mol%. With concentrations of less than 0.1 mol%, for example, 0.05 mol%, the substrate also contains materials such as B₂O₃, Al₂O₃, and NiO. The component also has at least one metal structure. The substrate and the metal structure are co-sintered.

[0014] Two or three different metal structures are also possible. The metal structures can be internal structures, meaning they can be located at least partially within the base body. Alternatively, they can be external structures, meaning they can be located on the exterior of the base body. Co-sintering means that the base body and the metal structure undergo a shared sintering process during the manufacturing of the component.

[0015] Bi2O3 may also be present as another material in the base body, for example in the range between 0.5 and 5 mol percent.

[0016] The base body is doped with a material of the metal structure. In particular, the base body is doped with a chemical compound of the metal of the metal structure. Preferably, the base body has a doping concentration of 0.1 to 1 mol percent, for example 0.5 or 0.7 mol percent, of a chemical compound of the metal of the metal structure. The amount of doping in the base body is preferably adjusted so that the base body is already saturated with the metal of the metal structure before a sintering process. The base body is preferably doped with the material of the metal structure in such a way that diffusion of material from the metal structure into the base body during a sintering process is reduced or preferably prevented.

[0017] The saturation of the base material with the metal of the metal structure means that it can no longer absorb any more material from the metal structure during sintering. This eliminates material loss from the metal structure during sintering. Consequently, the type and quantity of metal structures no longer need to be considered in relation to metal loss. For example, materials with low diffusion coefficients do not need to be used. Furthermore, it is no longer necessary to stock significantly more metal than is actually required after sintering; the amount of metal can be much smaller and more precisely dimensioned. This leads to cost reductions and significantly improved metal structures after sintering, which is particularly crucial for very small structures.

[0018] According to one embodiment, the metal structure has at least one internal electrode. The metal structure can have a plurality of internal electrodes. The internal electrodes are arranged within the multilayer device, particularly in the substrate. In particular, the multilayer device has alternating ceramic layers of the substrate with internal electrodes interspersed. Alternatively or additionally, the metal structure can have at least one external metallization, for example, two external metallizations. The external metallization is arranged on an outer surface of the device. Alternatively or additionally, the metal structure can have at least one via, for example, two, three, or four vias. The vias are arranged within the substrate. The vias serve for at least partial through-hole plating of the substrate. For example, an external metallization can be connected to an internal electrode via a via.

[0019] Preferably, the metal structure is doped. The metal structure is preferably doped with a material from the ceramic substrate. For example, the metal structure is doped with ZnO. Alternatively, the metal structure can be doped with Sb₂O₃, Bi₂O₃, CO₃O₄, Mn₂O₃, SiO₂, Cr₂O₃, B₂O₃, Al₂O₃, NiO, or a combination thereof.

[0020] Saturating the ceramic with the metal of the metal structures during co-sintering effectively prevents the disappearance or thinning of the metal structure. This allows for the formation of very thin internal electrodes, external metallizations, and / or vias. As a result, very small and universally applicable components can be realized. Preferably, the thickness or lateral extent of the metal structure is less than or equal to 1.5 µm. For example, an internal electrode thus has a thickness of 1.5 µm or less, such as 1.2 µm or 1.0 µm.

[0021] According to one embodiment, the base body comprises bismuth oxide. Alternatively, the base body can also comprise praseodymium oxide. Preferably, the base body is a ceramic sintered with liquid phases, wherein the metal structure is co-sintered. To produce the multilayer device, for example, with very thin internal metal structures, a ceramic must be provided that can be sintered below the melting point of the electrode material. Therefore, a liquid phase that exists at these low temperatures is required during sintering. Bismuth oxide, for example, has a melting point below 840 °C. Therefore, bismuth oxide is used as the liquid phase in the ceramic.

[0022] The use of bismuth oxide increases the diffusion of the metal structure material during sintering. However, by doping the substrate with the metal structure material, diffusion of the metal structure material during sintering can be effectively prevented despite the addition of bismuth oxide. This allows the overall amount of bismuth oxide used as a sintering aid to be increased without resulting in increased material loss from the metal structure. For example, increasing the proportion of bismuth oxide leads to a lower porosity of the component and thus to a component with improved properties.

[0023] According to one embodiment, the metal structure contains silver. The metal structure consists essentially of silver. Preferably, the metal structure contains more than 95% silver, for example, 98%, 99%, or 100%. In this case, the base material is doped with silver oxide or silver carbonate. Doping the base material with silver effectively prevents loss of electrode material from the metal structure through diffusion. At the same time, palladium can be omitted from the metal structure. Furthermore, it is unnecessary to use metals that are not easily oxidized, such as nickel or aluminum, for the metal structure. These metals cause many problems during co-sintering with the base material, which, for example, contains a large proportion of zinc oxide, thus impairing the quality of the multilayer device.

[0024] Due to the doping of the base body, the silver content in the base body is always independent of the sintering process, the formulation of the ceramic material of the base body, or the shape and quantity of the metal structures. This results in the base body exhibiting very consistent properties with regard to both its thermal properties (thermal expansion, shrinkage) and its electrical properties (capacitance, U-value, robustness), regardless of which and how many metal structures are used.

[0025] Furthermore, silver has a low melting point compared to other metals, such as palladium. Therefore, when using silver as the material for the metal structure, the sintering process must be carried out at relatively low temperatures, for example, 960°C or less.

[0026] According to one embodiment, the metal structure contains palladium. The metal structure consists essentially of palladium. Preferably, the metal structure contains more than 95%, for example, 98%, 99%, or 100% palladium. In this case, the base material is doped with a palladium compound. Palladium has a higher melting point than silver. By using palladium as the material of the metal structure, the sintering process can therefore also be carried out at higher temperatures, for example, 1100°C or more.

[0027] Due to the doping of the base body, the palladium content in the base body is always independent of the sintering process, the formulation of the ceramic material of the base body, or the shape and quantity of the metal structures. This results in the base body exhibiting very consistent properties with regard to both its thermal properties (thermal expansion, shrinkage) and its electrical properties (capacitance, U-value, robustness), regardless of which metal structures are used.

[0028] According to one embodiment, the metal structure comprises an alloy of palladium and silver. For example, the alloy consists of 70% silver and 30% palladium. In this case, the base material is doped with silver. The use of palladium and silver in the metal structure allows the sintering process to occur at temperatures below 1100°C but above 960°C. For example, sintering is performed here at a temperature of approximately 1000°C.

[0029] According to one embodiment, the multilayer component has at least one passivation layer. The passivation or insulating layer is preferably arranged on at least one surface of the base body. The passivation layer can be arranged around the entire surface of the base body. Alternatively, the passivation layer may only partially cover the surface of the base body. The passivation layer is designed and arranged to protect the component against moisture and chemical media and / or to provide electrical insulation.

[0030] The passivation layer comprises, for example, a ceramic and / or a glass with a filler material. The passivation can also consist of a varistor ceramic. Preferably, the passivation layer is co-sintered. In other words, the substrate, metal structure, and passivation layer undergo the sintering process together. The passivation layer is therefore applied to the substrate prior to the sintering process.

[0031] Preferably, the passivation layer is doped with the material of the metal structure, for example, silver or palladium. The doping concentration is higher than or equal to a saturation concentration of the metal structure material in the passivation layer. The passivation layer may also be doped with material from the ceramic substrate. Preferably, the passivation layer is doped with the main dopants from the ceramic substrate. The passivation layer may be doped with ZnO, Sb₂O₃, Bi₂O₃, CO₃O₄, Mn₂O₃, SiO₂, Cr₂O₃, B₂O₃, Al₂O₃, NiO, or a combination thereof.

[0032] If the passivation layer is sintered along with the metal structure, it acts as a sink for the diffusing material of the metal structure during sintering. Sufficient doping of the passivation layer with the same material as the metal structure, for example with silver, ensures that the passivation layer cannot absorb any further metal during sintering. This guarantees that the quality of the co-sintered metal structure remains consistent, regardless of the amount of passivation material used.

[0033] In the passivation layer, the doping concentration with the metal structure material is preferably higher than in the base body. Preferably, the passivation layer is doped with the metal structure material to more than 1 mol%, for example, 2 or 5 mol%. In particular, the doping concentration of the passivation layer can be higher than the saturation value, since there is no active region there, and the metal structure material in the base body can only rise to the saturation value, but not beyond.

[0034] According to another aspect, a process for manufacturing the multilayer component described above is specified. All characteristics described in connection with the multilayer component also apply to the process, and vice versa. The process comprises the following steps: - An arrangement of layers comprising a ceramic mass and layers comprising an electrode paste, alternately stacked on top of each other. The ceramic mass is doped with a material from the electrode paste, in particular with a chemical compound of the metal in the electrode paste. - Sintering of the layer stack to form ceramic layers with internal electrodes arranged in between.

[0035] Preferably, the ceramic mass is doped with the electrode paste material to a concentration of 0.1 to 1 mol percent.

[0036] The multilayer component produced by this process features a ceramic material doped with a portion of the electrode material, and in which the ceramic material is sintered together with the metallic material. Doping the ceramic reduces or prevents loss due to diffusion of the electrode material.

[0037] According to one embodiment, the electrode paste contains silver. Preferably, the electrode paste is further doped with a material from the ceramic mass. For example, the electrode paste is doped with ZnO. However, other dopings of the electrode paste with material from the ceramic mass (for example, with Sb₂O₃, Bi₂O₃, CO₃O₄, Mn₂O₃, SiO₂, Cr₂O₃, B₂O₃, Al₂O₃, NiO, or a combination thereof) are also conceivable.

[0038] The ceramic mass is preferably doped with silver oxide or silver carbonate. Alternatively, the electrode paste can also contain palladium, and the ceramic mass can be doped with a palladium alloy. Alternatively, the electrode paste can also be an alloy of palladium and silver, and the ceramic mass can be doped with silver.

[0039] According to one embodiment, the ceramic mass comprises zinc oxide and bismuth oxide. Sintering preferably takes place at a temperature of less than or equal to 1000°C, for example, at 960°C. In particular, sintering takes place at a temperature of 960°C or less if the electrode paste contains silver. For example, sintering takes place at a temperature greater than or equal to 1100°C, for example, 1200°C, if the electrode paste consists substantially of palladium. For example, sintering takes place at a temperature of approximately 1000°C if the electrode paste is an alloy of palladium and silver.

[0040] According to one embodiment, the method includes the following additional step: - Application of a passivation layer to at least one top surface of the ceramic mass, wherein the passivation layer is doped with a material from the electrode paste. The passivation layer can further be doped with a material from the ceramic mass. Preferably, the passivation layer is doped with the main dopants from the ceramic mass.

[0041] The passivation layer is preferably doped with a higher proportion of the electrode paste material than the ceramic mass. The passivation layer is applied before sintering. The passivation layer may, for example, contain an additional ceramic mass.

[0042] The invention will be explained in more detail below with reference to exemplary embodiments and the corresponding figures.

[0043] The drawings described below are not to be considered as being to scale. Rather, individual dimensions may be enlarged, reduced, or distorted for better illustration.

[0044] Elements that are identical or that perform the same function are designated with the same reference symbols. Fig. Figure 1 shows a schematic cross-sectional representation of a multilayer component. Fig. 2 shows the multi-layer component made of Fig. 1 in a supervisory role, Fig. Figure 3 shows a schematic cross-sectional representation of a multi-layer component. Fig. Figure 4 shows a schematic cross-sectional representation of a multilayer component. Fig. 5 shows the multi-layer component made of Fig. 4 in a supervisor's position, Fig. Figure 6A shows a photograph of a realized multilayer component according to the state of the art. Fig. Figure 6B shows a photograph of a realized multilayer component according to the invention, Fig. Figure 7 shows a photograph of a realized multilayer component according to the invention.

[0045] The Fig. Figure 1 shows a schematic representation of a multilayer component in cross-section.

[0046] The multilayer device 1 is a varistor multilayer device. The multilayer device 1 has a ceramic substrate 2. The substrate 2 consists of several layers. The multilayer device 1 has metal structures. In particular, in this embodiment, internal electrodes 3 are arranged between the layers of the substrate 2. The internal electrodes 3 and the ceramic substrate 2 are co-sintered to obtain the finished multilayer device 1.

[0047] In this embodiment, the base body 2 is a zinc oxide (ZnO) varistor. Specifically, the base body 2 comprises approximately 95 mol% ZnO. Bi₂O₃, for example in the range of 0.5 to 5 mol%, can also be included as a sintering aid in the base body.

[0048] The inner electrodes 2 comprise a metal. In particular, the inner electrodes 2 comprise silver (Ag). Preferably, the inner electrodes comprise more than 90% by weight of silver, for example, 95%, 98%, or 99% by weight. Alternatively, the inner electrodes 2 can comprise another metal, for example, palladium. Preferably, in this case, the inner electrodes 2 comprise essentially palladium.

[0049] The inner electrodes 2 are made particularly thin. In particular, the inner electrodes 2 have a thickness of less than or equal to 1.5 µm, for example 1.4 µm, 1.2 µm, or 1.0 µm. The thickness of the inner electrodes 2 is preferably selected such that it is just sufficient to withstand a sintering process. Due to the small thickness of the inner electrodes 2, the risk of delamination, in which the electrode layer separates from the ceramic material of the base body 2, thereby rendering the component 1 unstable, is significantly reduced. Furthermore, a thin electrode layer has the advantage that the volume of the component 1 can be utilized more efficiently while maintaining the same functionality.

[0050] The base body 2 also comprises electrode material. In particular, the base body 2 is doped with a chemical compound of the metal of the inner electrodes 2. Preferably, the ceramic material of the base body 2 is doped with silver oxide or silver carbonate. Alternatively, the base body can also be doped with a palladium compound if the inner electrodes 2 contain palladium. For example, the base body is doped with a chemical compound of the metal of the inner electrodes 2 in a proportion of between 0.1 and 1 mol percent.

[0051] By doping the ceramic material of the base body 2 with electrode material, diffusion of the material from the inner electrodes 2 into the ceramic volume during a sintering process can be controlled or prevented. In particular, the proportion of electrode material in the ceramic allows for a diffusion equilibrium to be achieved, which prevents the diffusion of electrode metal into the ceramic during sintering. The influence of the inner electrodes 2 on the ceramic properties can thus be reduced.

[0052] In this embodiment, after sintering the ceramic substrate 2 and internal electrodes 3, a passivation layer 4 is applied to the multilayer component 1. The passivation layer 4 is applied to a surface, or outer surface, of the substrate 2. In particular, the passivation layer 4 covers the entire surface of the substrate 2. The passivation layer 4 protects the substrate 2 from external influences. The passivation layer 4 can, for example, consist of glass with a filler material or a ceramic. The passivation layer 4 can also consist of a varistor ceramic.

[0053] Furthermore, the multilayer component 1 has external metallizations 5 for electrical connection. The external metallizations 5 are arranged on opposite sides of the component 1. The external metallizations 5 preferably consist of the same material as the internal electrodes 2. For example, the external metallizations 5 consist of silver.

[0054] The external metallizations 5 are arranged on the passivation layer 4. In this embodiment, the external metallizations 5 are also applied after the sintering process. Fig. Figure 2 shows the passivation layer 4 applied after sintering and the external metallizations 5 in a top view.

[0055] The Fig. Figure 3 shows a schematic representation of a multilayer component according to a further embodiment.

[0056] Unlike the one related to the Fig. 1 and Fig. The multilayer component described in 2 is present in Fig. In the multilayer component 1 shown in Figure 3, the passivation layer 4 is sintered together with the base body 2 and the internal electrodes 2. For this purpose, the passivation layer 4 is applied to the base body 2 before sintering. The passivation layer 4 is applied either to the entire surface of the base body 2 or only to partial areas of the surface of the base body 2.

[0057] To co-sinter the passivation layer 4, the material of the passivation layer 4 is doped with electrode material. Preferably, the passivation layer 4 is doped with silver. The silver doping can be equal to or greater than the saturation value of the silver in the passivation layer 4, because there is no longer an electrically active region in the passivation layer 4. Doping the passivation layer 4 prevents degradation of the metal structures (internal electrodes 2) during sintering.

[0058] The Fig. Figure 4 shows a schematic representation of a multilayer component according to a further embodiment.

[0059] In this embodiment, the multilayer component 1 has a ceramic base body 2, wherein the base body 2 is designed as a ZnO substrate or support element.

[0060] Metal structures are arranged within the base body 2. In particular, internal electrodes 3 and vias 6 are arranged within the base body 2. While the internal electrodes 3 extend horizontally through the base body 2, the vias 6 are arranged perpendicular to the internal electrodes 3. The internal electrodes 3, vias 6, and ceramic base body 2 are co-sintered to obtain the finished multilayer device 1.

[0061] The inner electrodes 2 and vias 6 comprise a metal. Preferably, the inner electrodes 2 and vias 6 comprise silver. Alternatively, the inner electrodes 2 and vias 6 can also comprise palladium, as described above. As already mentioned in connection with the embodiment according to the Fig. 1 and Fig. As described in Figure 2, the metal structures (inner electrodes 2, vias 6) are particularly thin. The inner electrodes 2 have a thickness of less than or equal to 1.5 µm, for example 1.0 µm or 1.2 µm. The vias 6 also have only a small lateral extent.

[0062] The base body 2 also contains material from the metal structures. This prevents diffusion of electrode material into the base body 2 during the sintering process. Furthermore, reference is made to the explanations in connection with the Fig. 1 and Fig. 2 referred.

[0063] Just like the multi-layer component 1 according to the Fig. 1 and Fig. 2, the multilayer component 1 exhibits according to Fig. 4 a passivation layer 4 and external metallizations 5. In this embodiment, the passivation layer 4 and external metallizations 5 are applied after the sintering process. Fig. Figure 5 shows the passivation layer 4 applied after sintering as well as the external metallizations 5 in a top view.

[0064] Similarly, passivation layer 4 and outer metallization 5 can also be co-sintered, as already described in connection with the preceding figures. In this case, sufficient doping with the material of the metal structures is required for passivation layer 4.

[0065] The following describes, by way of example, the process for manufacturing a multilayer component. In particular, a process for manufacturing a multilayer component with metal structures consisting primarily of silver is described. Alternatively, a multilayer component with metal structures consisting primarily of palladium or an alloy of palladium and silver can also be manufactured using a corresponding process.

[0066] To produce multilayer varistors, green ceramic films are first manufactured from the dielectric ceramic components. As already described, the ceramic films can contain the following components: - ZnO to approximately 95 mol percent; - Doping with Sb2O3, Bi2O3 in the range between 0.5 and 5 mol percent; - Doping with CO3O4, Mn2O3, SiO2, Cr2O3 in the range of 0.05 to 2 mol percent; - Doping with B2O3, Al2O3, and NiO with concentrations of less than 0.1 mol percent.

[0067] Furthermore, the ceramic must be such that it can be sintered with high quality even below the melting point of the metal structure material (preferably silver). Therefore, a liquid phase that exists at low temperatures is required during sintering. This is ensured by a liquid phase such as bismuth oxide. Consequently, the ceramic is based on zinc oxide doped with bismuth oxide. Doping with bismuth oxide generally increases the diffusion of silver from the inner electrodes 2, but this is prevented by doping the ceramic with silver.

[0068] The ceramic is doped specifically with silver oxide or silver carbonate. The doping concentration is chosen so that the ceramic is already saturated with silver before sintering. This saturation prevents the ceramic from absorbing any more silver during the sintering process. As a result, no material loss occurs in the metal structure (here: inner electrodes 2) during sintering. Doping the ceramic foils with silver oxide / silver carbonate also allows for the addition of a larger quantity of sintering aids, such as bismuth oxide, to the ceramic formulation, for example, to reduce porosity.

[0069] Finally, the ceramic also contains an organic binder preparation.

[0070] The inner electrodes 2 are applied to these ceramic foils by coating the green ceramic with a metallization paste in the electrode pattern. These metallized green foils are then stacked. The metallization paste, or electrode paste, used for the inner electrodes is a paste that essentially consists of silver as its metallic component.

[0071] The green body is then sintered, whereby the binder, in particular its organic components, evaporates. The sintering temperature is adjusted to the material of the inner electrodes 2. For the Ag inner electrodes, the sintering temperature is preferably less than 1000°C, particularly preferably less than 960°C. The sintering temperature is, for example, 900°C.

[0072] The diffusion of electrode material into the ceramic during sintering behaves as follows: At a sintering temperature of 900°C and a silver concentration of more than 0.1 mol percent in the ceramic foils, the diffusion constant is 7·10 -11 cm 2 / s. At a sintering temperature of 900°C and a silver concentration of less than 0.1 mol percent in the ceramic films, the diffusion constant is 3·10 -8 cm 2 / s.

[0073] Due to the doping of the ceramic, the silver content in the ceramic is independent of the sintering process, the ceramic formulation, or the shape and quantity of the metal structures. This results in the ceramic always possessing consistent properties in terms of both thermal properties (thermal expansion, shrinkage) and electrical properties (capacitance, U-value, robustness).

[0074] According to the embodiment shown Fig. The passivation layer 4 can also be co-sintered. In this case, the passivation layer 4 is applied to an outer surface of the ceramic foils before sintering. When co-sintering with the passivation material, the latter must also be doped with silver to prevent silver from diffusing into the passivation layer 4 during sintering. The doping concentration can be higher than the saturation value of the passivation material.

[0075] According to another embodiment, not shown, the outer metallization 5 can also be co-sintered. In this case, the outer metallization 5 is applied to an outer surface of the ceramic foils or to the passivation layer before sintering. The outer metallization 5 consists essentially of silver. The diffusion of the silver is prevented by the silver doping of the ceramic foils (and, in the case of co-sintering the passivation layer, also by its silver doping).

[0076] According to the embodiment shown Fig. 4, the base body 2 can be used as a substrate or support element after sintering. Fig. Figure 7 shows a photograph of a realized multilayer component. In this case, further metal structures (vias 6) can be introduced into the green body before sintering and subsequently co-sintered. These additional metal structures also consist primarily of silver. The diffusion of the silver is prevented by the silver doping of the ceramic foils (and, in the case of co-sintering, also by the silver doping of the passivation layer).

[0077] The Fig. Figure 6B shows a photograph of a realized multilayer component according to the invention. The regular shape of the inner electrodes 2 is particularly noticeable. It is especially evident that no material loss occurred in the inner electrodes 2 during the sintering process. This contrasts with multilayer components according to the prior art, in which the ceramic body is not doped with the electrode material (silver) (see Figure 6B). Fig. 6A).

[0078] The description of the objects and processes specified here is not limited to the individual specific embodiments. Rather, the features of the individual embodiments can be combined with one another as desired – insofar as this is technically feasible. Reference symbol list 1 Multi-layer component / component 2 basic shapes 3 Internal electrode 4 Passivation / Passivation layer 5 External metallization 6 Via

Claims

[1] Multilayer component (1) comprising a ceramic base body (2) and at least one metal structure (3, 5, 6), wherein - the metal structure (3, 5, 6) is co-sintered, - the base body (2) is a varistor ceramic sintered with liquid phases and has the following composition: - ≥ 95 % Mol ZnO, - from 0.5 to 5% mol Sb2O3, - from 0.05 to 2% mol CO3O4, Mn2O3, SiO2 and / or Cr2O3, - < 0.1 % mol B2O3, Al2O3 and / or NiO, - the metal structure (3, 5, 6) has silver and / or palladium and, - the ceramic base body (2) has a doping with material of the metal structure (3, 5, 6). [2] Multilayer component (1) according to claim 1, wherein the base body (2) is doped with the material of the metal structure (3, 5, 6) in such a way that diffusion of material from the metal structure (3, 5, 6) into the base body (2) during a sintering process is reduced. [3] Multilayer component (1) according to claim 1 or claim 2, wherein the base body (2) has a doping of 0.1 to 1 mol percent of a chemical compound of the material of the metal structure (3, 5, 6). [4] Multilayer component (1) according to claim 2 or 3, wherein the metal structure (3, 5, 6) has at least one inner electrode (3) and / or at least one outer metallization (5) and / or at least one via (6). [5] Multilayer component (1) according to one of claims 1 to 4, wherein the ceramic base body (2) comprises Bi2O3. [6] Multilayer component (1) according to any one of claims 1 to 5, wherein a thickness or lateral extent of the metal structure (3, 5, 6) is less than or equal to 1.5 µm. [7] Multilayer component (1) according to any one of claims 1 to 6, wherein the metal structure (3, 5, 6) comprises silver. [8] Multilayer component (1) according to claim 7, wherein the metal structure (3, 5, 6) has ≥ 99% silver. [9] Multilayer component (1) according to any one of claims 1 to 8, wherein the doping comprises silver oxide or silver carbonate. [10] Multilayer component (1) according to any one of claims 1 to 7, wherein the metal structure (3, 5, 6) comprises palladium. [11] Multilayer component (1) according to any one of claims 1 to 8, wherein the doping comprises a palladium compound. [12] Multilayer component (1) according to one of claims 1 to 11, comprising at least one passivation layer (4), wherein the passivation layer (4) is co-sintered, wherein a material of the passivation layer (4) comprises a glass with a filler material or a ceramic, and wherein the material is applied to the base body (2) prior to sintering. [13] Multilayer component (1) according to claim 12, wherein the passivation layer (4) is doped with at least one material of the metal structure (3, 5, 6), and wherein the doping of the passivation layer is higher than or equal to a saturation concentration of the material in the passivation layer (4). [14] Multilayer component (1) according to one of claims 1 to 13, wherein the metal structure (3, 5, 6) has a doping with at least one material of the ceramic base body (2). [15] Method for manufacturing a multilayer component (1) according to any one of claims 1 to 14 comprising the following steps: - Arranging layers comprising a ceramic mass and layers comprising an electrode paste alternately on top of each other to form a layer stack, wherein the ceramic mass is doped with a material of the electrode paste, - Sintering of the layer stack to form ceramic layers with internal electrodes arranged in between. [16] Method according to claim 15, wherein the ceramic mass is doped with at least one material of the electrode paste to 0.1 to 1 mol percent. [17] Method according to claim 15 or 16, wherein the electrode paste comprises silver, wherein the electrode paste is doped with at least one material of the ceramic mass, and wherein the ceramic mass is doped with silver oxide or silver carbonate. [18] Method according to any one of claims 15 to 17, comprising the additional step: - Applying a passivation layer to at least one top surface of the ceramic mass, wherein the passivation layer is doped with at least one material of the electrode paste and at least one material of the ceramic mass, and wherein the passivation layer is applied prior to sintering.

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