Metal-ceramic substrate with contact area

Abstract

To provide a metal-ceramic substrate which has an increased resistance to thermal shock.SOLUTION: A metal-ceramic substrate 1 comprises: a) a ceramic body 10 having a primary boundary surface 15; b) a metal layer 20 having a primary boundary surface, the metal layer being connected over its surface to the ceramic body, the metal layer comprising a structuring region 4 including (i) partially solid material 50 and (ii) partially non-solid material; and c) a contact area 8 containing silver 60, and disposed on the metal layer. In a cross-section through the metal-ceramic substrate perpendicular to the primary boundary surface of the ceramic body, the structuring region has a geometry satisfying the following requirement: S(BCsolid) / S(BCtotal)>60%, where S(BCtotal) stands for the total length of the line between points B and C, and S(BCsolid) stands for the length of the line between the points B and C that intersects the solid material. The solid material has an increased silver content in the region adjacent to the upper half of the contour line.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a metal-ceramic substrate, an electronic component comprising the metal-ceramic substrate, and a method for manufacturing the metal-ceramic substrate.

[0002] Metal-ceramic substrates play an important role in the field of power electronics. They are a key element when constructing electronic components, ensuring the rapid dissipation of large amounts of heat during their operation. Metal-ceramic substrates typically consist of a ceramic layer and a metal layer bonded to the ceramic layer.

[0003] Several methods for bonding metal layers to ceramic layers are known from the prior art. In the so-called DCB ("direct copper bonding") method, copper is reacted with a reactive gas (usually oxygen) to provide the surface of a copper foil with a copper compound (usually copper oxide) that has a lower melting point than copper. When the copper foil treated in this way is applied to a ceramic body and the composite is heated, the copper compound melts and wets the surface of the ceramic body, resulting in a stable cohesive bond between the copper foil and the ceramic body. This method is described, for example, in U.S. Pat. No. 3,744,120 (A) or German Patent No. 2,319,854 (C2).

[0004] In an alternative method, metal foils can be joined to ceramic bodies at temperatures of approximately 650-1000°C. A specific solder is used, containing a metal (usually silver) with a melting point of at least 700°C and an active metal. The role of the active metal is to react with the ceramic material, thus facilitating its joining to the remaining solder and forming a reaction layer, while the metal with a melting point of at least 700°C serves to join the reaction layer to the metal foil. For example, Patent No. 4812985 (B2) proposes joining copper foil to a ceramic body using a solder containing 50-89 weight percent silver, copper, bismuth, and an active metal. This method allows for a reliable joining of copper foil to the ceramic body. Alternatively, silver-free solders can be used to connect metal foils to ceramic bodies. These solders are based, for example, on a high-melting-point metal (especially copper), a low-melting-point metal (such as bismuth, indium, or tin), and an active metal (such as titanium). Such a technique is proposed, for example, in DE 102017114893 A1, which essentially results in a new and independent class of compounds, since the basis of the solder used is formed by another metal (copper instead of silver), leading to changes in the material properties and adaptation with regard to other solder constituents and modified joining conditions.

[0005] In the construction of electronic components, a metal-ceramic substrate is typically loaded with a chip. To load a chip onto a metal-ceramic substrate, it is typically necessary to provide a silver-containing contact area in the area of the metal-ceramic substrate where the chip will be loaded. By providing the silver-containing contact area, the chip can be more easily connected to the metal-ceramic substrate using common processes such as sintering or soldering. To create the contact area, the metal-ceramic substrate is typically first treated with an etching solution in specific areas to form the desired structure. The contact area is then provided by partially applying a silver-containing coating to the surface of the structured metal-ceramic substrate.

[0006] Metal-ceramic substrates manufactured in this way are typically exposed to large temperature changes during operation as part of electronic components. During interruptions, temperatures can drop to, for example, -20°C or below, depending on the environment, while the temperature of the metal-ceramic substrate can easily rise to over 150°C during operation. Metal-ceramic substrates are regularly exposed to these temperature differences. Due to the different thermal expansion coefficients of metal and ceramic, repeated temperature changes can cause the metal layer to peel off (delaminate) from the ceramic body, resulting in performance degradation. Therefore, high thermal shock resistance is an important criterion for the suitability of metal-ceramic substrates for electronics applications, especially power electronics applications.

[0007] Therefore, it is desirable to further improve the thermal shock resistance of metal-ceramic substrates.

[0008] It is therefore an object of the present invention to provide a metal-ceramic substrate with improved resistance to thermal shock.

[0009] This object is achieved by a metal-ceramic substrate according to claim 1. The invention therefore relates to a metal-ceramic substrate, a) a ceramic body having a primary boundary surface; b) a metal layer having a primary interface, the metal layer being connected to the ceramic body at a surface thereof, the metal layer comprising: (i) Partially comprised of solid material; (ii) a metal layer with structured regions partially comprising a non-solid material; c) a contact region comprising silver and disposed on the metal layer, In a cross section through the metal-ceramic substrate perpendicular to the primary interface of the ceramic body, the structured region has a geometric shape that meets the following requirements: S(BC solid ) / S(BC total )>60%, During the ceremony, S(BC total ) means the total length of the line between points B and C, S(BC solid) means the length of the line between points B and C that intersects the solid material, Points B and C are determined as follows: 1. A line of best fit between the ceramic body and the metal layer is determined; 2. The contour lines separating solid materials from non-solid materials are determined; 3. A point A where the perpendicular to the best fit line intersects the contour line is determined on the perpendicular to the best fit line at a distance of 150 μm from the best fit line; 4. A point B where the perpendicular to the best fit line intersects the contour line is determined on the perpendicular to the best fit line at a distance of 80 μm from the best fit line; 5. On the line passing through points A and B, point C is determined where the line intersects with the line of best fit; A metal-ceramic substrate is provided, wherein a contour line extends from a primary boundary surface of the metal layer to a primary boundary surface of the ceramic body, the contour line having an upper half and a lower half, the upper half of the contour line extending from the primary boundary surface of the metal layer toward the primary boundary surface of the ceramic body, and the lower half of the contour line extending from the primary boundary surface of the ceramic body toward the primary boundary surface of the metal layer, and wherein the solid material in the region adjacent the upper half of the contour line has a higher silver content than the region adjacent the lower half of the contour line.

[0010] Furthermore, the present invention relates to electronic components comprising such metal-ceramic substrates.

[0011] Additionally, the present invention relates to a method for manufacturing a metal-ceramic substrate.

[0012] A metal-ceramic substrate according to the present invention comprises a ceramic body having a primary interface.

[0013] The ceramic body is preferably a body made of ceramic. The body can have any geometric shape, but is preferably designed as a rectangular parallelepiped. The ceramic body has boundary surfaces, and in the case of a rectangular parallelepiped, it has six boundary surfaces. The primary boundary surface in this specification preferably refers to the boundary surface (particularly very preferably the boundary surface with the largest surface area) that is connected to the metal layer at its surface. The primary boundary surface is particularly preferably the boundary surface (particularly very preferably the boundary surface with the largest surface area) that is connected to the metal layer with the structured region at its surface, and particularly very preferably the boundary surface (particularly the boundary surface with the largest surface area) that is connected to the metal layer on which the silver-containing contact region is located at its surface. The primary boundary surface is preferably located in the primary extension plane of the ceramic body or extends parallel to it. Therefore, the primary extension plane of the ceramic body is preferably understood to be a plane that extends parallel to or surrounds the primary boundary surface of the ceramic body.

[0014] The ceramic of the ceramic body is preferably an insulating ceramic. According to a preferred embodiment, the ceramic is selected from the group consisting of oxide ceramics, nitride ceramics, and carbide ceramics. According to a further preferred embodiment, the ceramic is selected from the group consisting of metal oxide ceramics, silicon oxide ceramics, metal nitride ceramics, silicon nitride ceramics, boron nitride ceramics, and boron carbide ceramics. According to a particularly preferred embodiment, the ceramic is selected from the group consisting of aluminum nitride ceramics, silver nitride ceramics, and aluminum oxide ceramics (such as ZTA ("zirconia toughened alumina") ceramics). According to yet another very particularly preferred embodiment, the ceramic body comprises (1) at least one element selected from the group consisting of silicon and aluminum, (2) at least one element selected from the group consisting of oxygen and nitrogen, optionally (3) at least one element selected from the group consisting of (3a) rare earth metals, (3b) metals of Group 2 of the Periodic Table of the Elements, (3c) zirconium, (3d) copper, (3e) molybdenum, and (3f) silicon, and optionally (4) unavoidable impurities. According to yet another very particularly preferred embodiment, the ceramic body is free of bismuth, gallium, and zinc.

[0015] The ceramic body preferably has a thickness in the range of 0.05 to 10 mm, more preferably in the range of 0.1 to 5 mm, and particularly preferably in the range of 0.15 to 3 mm.

[0016] The metal-ceramic substrate according to the present invention comprises a metal layer having a primary interface, the metal layer being connected at its surface to a ceramic body, the metal layer comprising a structured region (i) partially comprising a solid material and (ii) partially comprising a non-solid material.

[0017] The metal layer has a boundary surface. The metal layer has a primary boundary surface. The primary boundary surface is preferably referred to herein as the boundary surface (particularly and very preferably the boundary surface with the largest surface area) that is located opposite the ceramic body. The primary boundary surface is therefore preferably referred to as the boundary surface (particularly and very preferably the boundary surface with the largest surface area) where the silver-containing contact area is located. The primary boundary surface is preferably located in a primary extension plane of the metal layer or extends parallel to it. The primary extension plane of the metal layer is therefore preferably understood to be a plane that extends parallel to or surrounds the primary boundary surface of the metal layer. The primary boundary surface of the metal layer preferably extends parallel to the primary boundary surface of the ceramic body, and particularly preferably is spaced apart from it.

[0018] The metal layer is preferably integrally bonded to the ceramic body. According to a preferred embodiment, the metal layer is bonded to the ceramic body by a DCB (direct copper bonding) process. According to a further preferred embodiment, the metal layer is connected to the ceramic body by a brazing process. The brazing process can be, for example, an AMB (active metal brazing) process, and preferably, a silver-free brazing alloy (the silver content is, for example, less than 1.0 weight percent, based on the solid content of the brazing alloy) or a silver-containing brazing alloy (the silver content is, for example, at least 50 weight percent, based on the solid content of the brazing alloy) is used. Thus, the metal layer may comprise a bonding layer in contact with the ceramic body. The bonding layer can be, for example, a solder layer (particularly a brazing layer) or a diffusion layer.

[0019] The metal layer is connected to the ceramic body at its surface. Thus, the metal layer is preferably connected to the primary boundary surface of the ceramic body at its surface. The metal layer is preferably not connected to the entire primary boundary surface of the ceramic body. In particular, the primary boundary surface of the ceramic body can be larger than the surface of the metal layer connected to the ceramic body. In these cases, the primary boundary surface of the ceramic body protrudes. In addition, the metal layer is preferably structured. Structured portions are preferably understood to mean recesses in the metal layer that separate individual parts of the metal layer from each other and thus electrically insulate them. Such structured portions are usually made using etching techniques.

[0020] The metal layer thus comprises a structured region. The structured region is a portion of the metal layer that includes a structure. The structure is preferably a recess in the metal layer. The primary interface of the metal layer thus includes metal of the metal layer interrupted by the recess in the structured region.

[0021] The structured region comprises regions containing solid material and regions containing non-solid material.

[0022] The region comprising the solid material preferably contains (i) the metal of the metal layer (optionally including the bonding layer, if present) and (ii) the metal of the contact region (particularly silver).

[0023] The region containing the non-solid material preferably contains a gaseous material. Therefore, the non-solid material preferably contains a gaseous material. The non-solid material is preferably a gaseous material that fills the recesses of the metal layer. This gaseous material is usually derived from the ambient atmosphere. Therefore, preferably, the gaseous material contains at least one element selected from the group consisting of nitrogen, oxygen, and a noble gas. Most preferably, the gaseous material is a mixed gas, in particular air.

[0024] In a preferred embodiment, the recesses extend in a direction perpendicular to the primary boundary surface of the ceramic body from the primary boundary surface of the ceramic body to the primary boundary surface of the metal layer, and the recesses form channels that are preferably filled with the non-solid material by at least 50 volume percent, more preferably by at least 80 volume percent, even more preferably by at least 90 volume percent, particularly preferably by at least 95 volume percent, very particularly preferably by at least 99 volume percent, and especially completely.

[0025] The metal layer preferably comprises at least one metal selected from the group consisting of copper, aluminum, and molybdenum. According to a further preferred embodiment, the metal layer comprises at least one metal selected from the group consisting of copper and molybdenum. According to a very particularly preferred embodiment, the metal layer comprises copper. According to a further preferred embodiment, the metal layer consists of copper and unavoidable impurities. According to a further preferred embodiment, the proportion of copper is at least 60 weight percent, more preferably at least 65 weight percent, even more preferably at least 70 weight percent, and particularly preferably at least 75 weight percent, based on the total weight of the metal layer (preferably including any bonding layer that may be present).

[0026] According to a preferred embodiment, the metal layer is produced by joining a copper foil (preferably a high-purity copper foil) to the ceramic body. According to a preferred embodiment, the connection can be made by a DCB (direct copper bonding) process or a brazing process. The brazing process can be, for example, an AMB (active metal brazing) process, and preferably, a silver-free brazing alloy (the silver content is, for example, less than 1.0 weight percent based on the solid content of the brazing alloy) or a silver-containing brazing alloy (the silver content is, for example, at least 50 weight percent based on the solid content of the brazing alloy) is used. In this case, the metal layer may contain, in addition to the copper originating from the copper foil, the metal of the joining layer, in particular the metal of the solder layer (e.g., brazing layer) or the metal of the diffusion layer.

[0027] The metal layer preferably has a thickness in the range of 0.01 to 10 mm, particularly preferably in the range of 0.03 to 5 mm, very particularly preferably in the range of 0.05 to 3 mm.

[0028] The metal-ceramic substrate according to the present invention includes a contact area comprising silver and disposed on the metal layer. The contact area preferably serves to facilitate connection of a chip to the metal layer. The chip is preferably connected to the metal layer by sintering, soldering, or adhesive bonding. In particular, since it is not easy to attach a chip to the metal of the metal layer of the metal-ceramic substrate, the metal layer is preferably provided with a contact area. The contact area is preferably made of silver or a silver-containing alloy. In the case of a silver-containing alloy, it contains at least 50% by weight of silver based on the weight of the silver alloy. Preferably, the contact area is provided in the metal layer of the metal-ceramic substrate at all positions where a chip will later be mounted on the metal-ceramic substrate. The contact area can be formed on the metal layer of the metal-ceramic substrate using various techniques. For example, the contact area can be provided by depositing a silver-containing layer. The deposition of the silver-containing layer is preferably carried out chemically (e.g., electrochemically) or physically. The chemical deposition of the silver-containing layer can be carried out, for example, galvanically or electrolessly. Preferably, the chemical deposition of the silver-containing layer is carried out electrolessly by applying a silver-containing solution, whereby charge is exchanged between the metals, partially dissolving the metal of the metal layer, while the silver in the solution is deposited. According to a preferred embodiment, the silver-containing solution contains a silver salt, particularly preferably silver nitrate. According to a particularly preferred embodiment, the silver-containing solution is an acidic solution of silver nitrate, particularly preferably a nitric acid solution of silver nitrate. The physical deposition of the silver-containing layer can be carried out, for example, by vapor deposition. Preferred methods of vapor deposition are, in particular, electron beam deposition, laser beam deposition, arc discharge deposition, or cathode sputtering.

[0029] The structured regions of the metal layer of the metal-ceramic substrate have the geometries described herein, where the geometry of the structured regions is determined in a cross section through the metal-ceramic substrate perpendicular to the primary interface of the ceramic body.

[0030] In a cross section through the metal-ceramic substrate perpendicular to the primary interface of the ceramic body, the structured area of the metal layer has a geometric shape that satisfies the following requirements: S(BC solid ) / S(BC total )>60%, During the ceremony, S(BC total ) means the total length of the line between points B and C, S(BC solid ) means the length of the line between points B and C that intersects the solid material.

[0031] According to a preferred embodiment, the structured area of the metal layer has a ratio S(BC solid ) / S(BC total ) is >70%, more preferably >80%, even more preferably >85%, particularly preferably >90%, very particularly preferably >95%.

[0032] According to a further preferred embodiment, the structured area of the metal layer has a ratio S(BC solid ) / S(BC total ) is in the range of 70 to 100%, particularly preferably in the range of 80 to 100%, very particularly preferably in the range of 80 to 99%.

[0033] To determine points B and C, a cross section of the structured region of the metal layer of the metal-ceramic substrate is observed. The cross section extends perpendicular to the primary boundary surface of the ceramic body. Preferably, the cross section is observed by cutting the metal-ceramic substrate perpendicular to the primary boundary surface of the ceramic body and capturing an image of the cross section thus obtained by optical microscopy.

[0034] Points B and C of line BC can be determined in cross section as described below. [Brief explanation of the drawings]

[0035] For illustrative purposes, reference is made to FIGS. 1 and 2 by way of example. [Figure 1] FIG. 1 shows a schematic diagram of this type of metal-ceramic substrate. [Figure 2] FIG. 2 shows diagrammatically a metal-ceramic substrate according to the invention having a structured region in which the solid material in the region adjacent to the upper half of the contour line has a higher silver content than in the region adjacent to the lower half of the contour line. [Figure 3] FIG. 3 shows a portion of a cross section through a metal-ceramic substrate according to the present invention. [Figure 4] FIG. 4 shows an example of an optical microscope photograph of a cross section of a structured area of the copper layer of a copper-ceramic substrate according to Example 1. [Figure 5] FIG. 5 shows an example of an optical microscope photograph of a cross section of a structured area of the copper layer of a copper-ceramic substrate according to Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0036] The metal-ceramic substrate 1 shown in FIG. 1 comprises a ceramic body 10. The ceramic body 10 has a primary boundary surface 15. The metal-ceramic substrate 1 comprises a metal layer 20. The metal layer 20 has a primary boundary surface 24 parallel to the primary boundary surface 15 of the ceramic body 10 on the upper surface opposite the primary boundary surface 15 of the ceramic body 10. The metal layer 20 is connected to the primary boundary surface 15 of the ceramic body 10 at its surface. In the embodiment according to FIG. 1, the metal-ceramic substrate 1 further comprises a further metal layer 200 connected to the ceramic body 10 at its surface. The metal layer 20 has contact areas 8 comprising silver. The metal layer 20 comprises a structured portion, which is formed by recesses 22 in the metal layer 20. The recesses 22 comprise a non-solid material. The structured area 4 partially comprises the metal of the metal layer 20 and the recesses 22. Thus, the structured area 4 partially comprises a solid material 50 formed by the metal of the metal layer 20 and a non-solid material (e.g., a gas-phase material) filling the recesses 22. The gas phase material is typically ambient air. Solid material 50 is separated from the non-solid material of recesses 22 by contour lines 40. Primary interface 24 of metal layer 20 includes metal of metal layer 20 interrupted by recesses 22 in the structured regions. Recesses 22 extend from primary interface 24 of metal layer 20 to primary interface 15 of ceramic body 10 in a direction perpendicular to primary interface 15 of ceramic body 10, preferably forming channels that are completely or mostly filled with the non-solid material.

[0037] The metal-ceramic substrate shown in Figure 2 has the same basic structure as the metal-ceramic substrate shown in Figure 1. A contour line 40 has an upper half and a lower half. The upper half of contour line 40 extends from primary interface 24 of metal layer 20 toward primary interface 15 of ceramic body 10. The lower half of contour line 40 extends from primary interface 15 of ceramic body 10 toward primary interface 24 of metal layer 20. Solid material 50 includes silver 60 in the region adjacent to the upper half of contour line 40. In the region adjacent to the lower half of contour line 40, the solid material contains no or less silver 60.

[0038] In a cross section through the metal-ceramic substrate according to the invention shown in Figure 3, a portion of the structured region is visible. A region of the ceramic body 10 is shown that is connected at its surface to a region of the metal layer 20. A contour line 40 separates the non-solid material of the recess 22 in the metal layer 20 from the solid material 50.

[0039] The determination of points B and C of line BC in the cross section is preferably done in several steps. In a first step, a best fit line 30 is determined between the ceramic body 10 and the metal layer 20. For this purpose, an area of the ceramic body 10 and an area of the metal layer 20 are optically determined, and the best fit line 30 is defined as the boundary between the ceramic body 10 and the metal layer 20 that can be observed in cross section.

[0040] In a second step, a contour line 40 is determined that separates the solid material 50 from the non-solid material of the recess 22. The solid material 50 is determined optically and is typically the material of the metal layer 20. The non-solid material is also determined optically. The non-solid material is typically a gas phase material that fills the structuring of the metal layer 20 as recess 22.

[0041] In a third step, a point A where the perpendicular to the best fit line 30 intersects the contour line 40 is determined on the perpendicular to the best fit line 30 at a distance of 150 μm from the best fit line 30 .

[0042] In a fourth step, a point B where the perpendicular to the best fit line 30 intersects with the contour line 40 is determined on the perpendicular to the best fit line 30 at a distance of 80 μm from the best fit line 30 .

[0043] In the fifth step, a point C on the line passing through points A and B where the line intersects with the line of best fit 30 is determined.

[0044] A cross section of the metal-ceramic substrate perpendicular to the primary interface of the ceramic body and an image of the cross section thus obtained are captured by optical microscopy (incident light / bright field) preferably as described below. In the first step, a 100 mm sample is first taken from the metal-ceramic substrate to be inspected. 2 ~Max 400mm 2 A rectangular sample blank with a rectangular base in the range of 0.01 mm was cut out by sawing perpendicular to the plane formed by the primary interface of the ceramic body of the metal-ceramic substrate using a diamond saw blade and lubricant (Exakt) at a low rotational speed. The sample blank thus had a sample surface to be inspected. This sample surface therefore extended perpendicular to the plane formed by the primary interface of the ceramic body of the metal-ceramic substrate before sawing. It therefore comprised a portion of the ceramic body and a portion of the metal layer (including an optional bonding layer). The sample blank was first embedded in a mold containing low-shrinkage epoxy resin (Caldo-Fix, Struers), with the sample surface oriented perpendicular to the mold wall. The epoxy resin was then cured at 75°C in a drying oven. After curing, the sample surface of the sample blank was mechanically polished with an automatic polishing machine (Tegrapole, Struers) to achieve a roughness of 1 μm or less.

[0045] In a second step, structured areas partially containing solid and partially containing non-solid material are identified in the metal layer using an optical microscope (Leica, DM6000M, incident light / bright field) at a magnification of 200x in the analysis zone. The solid and non-solid materials can be clearly distinguished in the structured areas by their different colors.

[0046] Line S(BC total ) and S(BC solid The length of ) is preferably determined by standard methods, for example using image analysis software (eg IMS Client, Imagic).

[0047] Preferably, the term "in cross sections" as used herein refers to a (preferably representative) total number of cross sections, particularly preferably at least 10 cross sections, very particularly preferably not more than 20 cross sections, in particular 10 cross sections. The cross sections preferably extend parallel to one another and are evenly spaced from one another.

[0048] The ratio S(BC) for the observed metal-ceramic substrates solid ) / S(BC total To determine , the following procedure is preferably used: 1. At least 10, particularly preferably 10, different cross sections of the structured area are examined. 2. The ratio S(BC) for each of these cross sections solid ) / S(BC total ) is required. 3. The ratio S(BC) for each of these cross sections solid ) / S(BC total ) and the ratio S(BC solid ) / S(BC total ) is obtained.

[0049] According to a preferred embodiment, the ratio S(BC) over at least 10 different cross sections of the structured area of the metal layer, more preferably over 20 or less different cross sections of the structured area of the metal layer, very particularly preferably over 10 different cross sections of the structured area of the metal layer. solid ) / S(BC total The sample standard deviation (SSD) of the sample (SSD) is 10% or less, more preferably 7% or less, particularly preferably 5% or less, and very particularly preferably 3% or less. The sample standard deviation (SSD) is calculated using the following formula:

[0050]

number

[0051]

number

[0052] According to the present invention, in a cross section through the metal-ceramic substrate perpendicular to the primary boundary surface of the ceramic body, the structured region has a geometric shape in which a contour line extends from the primary boundary surface of the metal layer to the primary boundary surface of the ceramic body, the contour line having an upper half and a lower half, the upper half of the contour line extending from the primary boundary surface of the metal layer toward the primary boundary surface of the ceramic body, and the lower half of the contour line extending from the primary boundary surface of the ceramic body toward the primary boundary surface of the metal layer, and the solid material in the region adjacent the upper half of the contour line has a higher silver content than the region adjacent the lower half of the contour line.

[0053] Thus, according to the present invention, the contour line extends from the primary boundary surface of the metal layer to the primary boundary surface of the ceramic body. The contour line preferably does not extend along the primary boundary surface of the ceramic, and does not extend along the primary boundary surface of the metal layer. Thus, the contour line preferably extends over an area that does not include the primary boundary surface of the ceramic and the primary boundary surface of the metal layer.

[0054] The contour line has an upper half and a lower half, the upper half of the contour line extending from the primary boundary surface of the metal layer toward the primary boundary surface of the ceramic body, and the lower half of the contour line extending from the primary boundary surface of the ceramic toward the primary boundary surface of the metal layer.

[0055] According to the invention, the solid material in the region adjacent to the upper half of the contour line has a higher silver content than the region adjacent to the lower half of the contour line. According to a preferred embodiment, the ratio of the silver content of the solid material in the region adjacent to the upper half of the contour line to the silver content of the solid material in the region adjacent to the lower half of the contour line is less than 0.8, more preferably less than 0.5, even more preferably less than 0.3, particularly preferably less than 0.1, and very particularly preferably less than 0.05.

[0056] The region of the solid material adjacent to the contour line preferably has a width in the range of 0.3 to 1.0 μm, particularly preferably in the range of 0.5 to 0.6 μm, and very particularly preferably 0.5 μm. Thus, the contour line preferably represents the outline of the solid material, and the composition of the solid material (including the silver content) is preferably determined using the method described above in a region bounded by (i) the primary boundary surface of the metal layer, (ii) the primary boundary surface of the ceramic body, (iii) the contour line, and (iv) a translation of the contour line toward the solid material of 0.3 to 1.0 μm, particularly preferably 0.5 to 0.6 μm, and very particularly preferably 0.5 μm. The contour line is preferably divided into upper and lower halves midway between the primary boundary surface of the metal layer and the primary boundary surface of the ceramic body, with the upper half of the contour line extending from the primary boundary surface of the metal layer toward the primary boundary surface of the ceramic body, and the lower half of the contour line extending from the primary boundary surface of the ceramic body toward the primary boundary surface of the metal layer. The area of the solid material being measured therefore consists of an upper half adjacent to the upper half of the contour line and a lower half adjacent to the lower half of the contour line.

[0057] The silver content of the solid material in the region adjacent the upper half of the contour line and the silver content of the solid material in the region adjacent the lower half of the contour line are preferably determined by energy dispersive X-ray spectroscopy (EDX) in combination with a scanning electron microscope (SEM) (SEM-EDX).

[0058] In SEM-EDX, a focused primary electron beam is guided (scanned) point-by-point over the sample surface. The scattered electrons are detected using a detector, and the number of electrons per pixel results in a grayscale microscopic image of the sample surface. Furthermore, the primary electron beam excites the sample to emit characteristic X-ray radiation, and the elements and their weight percentages in the sample can be determined by analyzing the energy spectrum using an EDX detector.

[0059] For the inspection, a scanning electron microscope (JSM-6060 SEM, JEOL Ltd) equipped with a silicon drift EDX detector (NORAN, Thermo Scientific Inc.) and analysis software (Pathfinder Mountaineer EDS System, e.g., version 2.8, Thermo Scientific Inc.) can be used. The following settings can be used for the scanning electron microscope: magnification: 200x, acceleration voltage: 10 kV, working distance: 10 mm, spot size: 50-60 (set to reach 25% + / - 5% of the EDX detector dead time). EDX spectra can be captured using the following settings for the EDX detector: live time: 30 s, speed: auto, low energy cutoff: 100 keV, high energy cutoff: auto (per SEM acceleration voltage). Depending on the selected magnification and the thickness of the metal layer, several SEM-EDX measurements may be required to image the entire structured area.

[0060] The silver content is measured in an area adjacent to the upper half of the contour line and in an area adjacent to the lower half of the contour line at at least five, and particularly preferably ten, representative positions within each area, and the silver content is preferably understood to be the arithmetic mean value of each individual measurement.

[0061] Surprisingly, it has been found that metal-ceramic substrates having a geometry according to the present invention have improved thermal shock resistance compared to prior art metal-ceramic substrates. These metal-ceramic substrates have a high percentage of solid material in the metal layer at the interface with the surface of the ceramic body. In contrast, it has been found that the percentage of solid material in the metal layer at the interface with the surface of the ceramic body is significantly lower in prior art metal-ceramic substrates when they include a contact area comprising silver disposed in the metal layer.

[0062] Without being bound by any explanation, this may be due to the fact that in the prior art, manufactured metal-ceramic substrates are usually first structured and then silver-plated on the surface to create contact areas; however, the already structured areas of the surface of the metal-ceramic substrate are only insufficiently masked during silver plating. For this purpose, areas of the surface of the structured metal-ceramic substrate that will not be coated with silver are usually first masked before silver plating. A film (e.g., a dry film) is usually used for masking. This film spans the structured areas of the metal-ceramic substrate, so that the structured areas are covered but not completely lined, especially in areas close to the ceramic body. Subsequent silver plating is usually carried out by immersing the structured and masked metal-ceramic substrate in a bath containing a solution containing silver ions. The silver-ion-containing solution can wash under the masking film, so that it comes into direct contact with the underlying structured areas. During the silver plating process, metal ions are electrochemically dissolved from the metal layer of the metal-ceramic substrate in the structured area and replaced by silver ions. It has been shown that the dissolution of metal ions from the metal layer and the deposition of silver ions occur in spatially separated regions near the ceramic body. Therefore, while silver deposition often occurs directly on the surface of the structured area, metal ions are preferably released from the area closer to the ceramic body (up to a distance of about 50 μm from the ceramic body surface). As a result, the surface of the structured area closer to the ceramic body is gradually removed over time as contact with the silver ion-containing solution progresses. This results in the removal of solid material, particularly the metal of the metal foil, from the metal foil in the area closer to the ceramic body, thus creating a weak point for peeling of the metal layer from the ceramic body, which adversely affects thermal shock resistance. Therefore, the removal of solid material in the structured area can be attributed to the lack of lining of the structured area with a masking film. However, according to the present invention, a structured area containing a sufficient amount of solid material in the area closer to the ceramic body can be created, thereby preventing peeling of the metal layer from the ceramic body and achieving improved thermal shock resistance.

[0063] The solid material contains silver in the region adjacent to the upper half of the contour line. This is because, according to one embodiment, a mask is applied by a printing process before silver plating. Since the structure of the metal-ceramic substrate usually has a curved geometry, the structure is (almost) completely covered by the mask in the region close to the ceramic body, improving thermal shock resistance. In contrast, regions of the structure further away from the ceramic body are usually not completely masked and are therefore at least partially coated with silver in the subsequent silver plating step.

[0064] According to a preferred embodiment, the metal-ceramic substrate comprises a further (second) metal layer connected at its surface to the ceramic body. The further metal layer is preferably connected at its surface to the ceramic boundary surface opposite the primary boundary surface (preferably extending parallel to the primary boundary surface). The further (second) metal layer may be of the same nature as the (first) metal layer or may have properties different from those of the (first) metal layer. For the properties of the further (second) metal layer, reference is made to the above explanations regarding the (first) metal layer.

[0065] The metal-ceramic substrate according to the invention can be used in particular for applications in electronics, especially in the field of power electronics.

[0066] The present invention therefore also provides an electronic component comprising a metal-ceramic substrate according to the present invention.

[0067] According to a preferred embodiment, an electronic component comprises a metal-ceramic substrate according to the invention and at least one chip. The at least one chip is preferably connected at its surface to a contact area comprising silver arranged on a (first) metal layer. Thus, the electronic component preferably comprises a chip in contact with the (first) metal layer of the metal-ceramic substrate via a contact area comprising silver.

[0068] According to a further preferred embodiment, the metal-ceramic substrate of the electronic component comprises a further (second) metal layer, which is preferably connected at its surface to the ceramic body, in which case the further metal layer is preferably connected at its surface to a boundary surface of the ceramic body opposite to (preferably extending parallel to) the primary boundary surface of the ceramic body.

[0069] According to a further preferred embodiment, the electronic component comprises a base plate, which is preferably connected at its surface to a further (second) metal layer of the metal-ceramic substrate, which may alternatively be designed as a heat sink.

[0070] According to a further preferred embodiment, the electronic component comprises a metal-ceramic substrate comprising a (first) metal layer and a further (second) metal layer (the further metal layer is preferably connected at its surface to the boundary surface opposite the primary boundary surface of the ceramic body), a base plate and at least one chip, wherein the at least one chip is connected at its surface to the first metal layer of the metal-ceramic substrate via contact areas arranged in the metal layer, which comprise silver, and the base plate is connected over its surface to the further (second) metal layer of the metal-ceramic substrate.

[0071] The metal-ceramic substrate according to the invention can be obtained by various manufacturing processes.

[0072] The present invention also provides a method for producing a metal-ceramic substrate provided with a structuring portion and a contact area comprising silver.

[0073] A method for producing a metal-ceramic substrate provided with a structure and a contact area comprising silver comprises the steps of: a) providing a metal-ceramic substrate, the metal-ceramic substrate comprising: a1) a ceramic body; a2) a metal layer connected to the ceramic body at its surface; b) structuring the metal layer; c) applying a mask to the structured metal layer by applying a liquid medium containing a masking agent to specific areas of the structured metal layer and allowing the masking agent to solidify; d) depositing a silver-containing layer on the unmasked areas of the structured metal layer to obtain contact areas comprising silver; e) removing the mask.

[0074] In step a), a metal-ceramic substrate is first provided.

[0075] The metal-ceramic substrate comprises a ceramic body and a metal layer connected to the ceramic body at a surface thereof. The metal-ceramic substrate can be a standard metal-ceramic substrate. The ceramic body and metal layer can have compositions as described above for the metal-ceramic substrate. The metal layer can preferably be integrally bonded to the ceramic body as described above for the metal-ceramic substrate.

[0076] In step b), the metal layer is structured.

[0077] The structuring is preferably understood to mean recesses in the metal layer that separate individual parts of the metal layer from one another and thus electrically insulate them. The structuring thus preferably exposes areas of the ceramic body. Such structuring is usually produced using etching techniques. For example, an etching mask can first be applied to the metal layer. The etching mask serves to protect the masked areas of the metal layer from etching in the etching step. This ensures that only the unmasked areas of the metal layer of the metal-ceramic substrate that are intended to be structured are accessible for etching. The etching mask is therefore designed to prevent etching of the masked areas of the metal layer during the etching step. The type of etching mask is not further limited. The etching mask can be, for example, a standard negative or positive mask. Standard etching resists can be used to produce the etching mask. These etching resists preferably contain a curable polymer (e.g., a photocurable polymer) and can be applied to the metal layer, for example, as a film (e.g., as a dry film) or as a liquid (e.g., by printing or spraying). After application, the etching resist can be treated in an appropriate manner (for example, cured by irradiation with light) to obtain an etching mask. According to one possible embodiment, a photosensitive film is applied to the metal layer of the metal-ceramic substrate and then exposed to light in the areas to be masked to obtain an etching mask. The unexposed areas of the photosensitive film can then be removed in a conventional manner (for example, using a sodium carbonate solution).

[0078] After applying the etching mask to the metal layer, the unmasked areas of the metal layer are preferably etched to obtain the structuring. Etching is preferably carried out in a standard, conventional manner. Therefore, etching is preferably carried out using a standard etching solution. According to a preferred embodiment, the etching solution is selected from the group consisting of FeCl3 etching solutions and CuCl2 etching solutions. If necessary, for example, to structure the unmasked areas of the optionally included bonding layer, a further etching solution can be used. According to a preferred embodiment, the further etching solution can be selected from the group consisting of an etching solution containing hydrogen peroxide and an etching solution containing ammonium persulfate. For example, the further etching solution can be an etching solution containing ammonium fluoride and fluoroboric acid (e.g., HBF4) and hydrogen peroxide and / or ammonium persulfate.

[0079] Preferably, after etching the unmasked areas of the metal layer to obtain the structuring, the etching mask is removed. The etching mask can be removed by standard methods. For example, the metal-ceramic substrate can be treated with an alkaline solution (e.g., 2.5% sodium hydroxide solution) to remove the etching mask.

[0080] In step c), a mask is applied to the structured metal layer by applying a liquid medium containing a masking agent to specific areas of the structured metal layer and allowing the masking agent to solidify.

[0081] The mask serves to protect the masked areas of the metal layer from the deposition of the silver-containing layer in step d), thereby ensuring that the silver-containing layer is deposited only on the unmasked areas of the metal layer of the metal-ceramic substrate. Therefore, the mask is designed so that the silver-containing layer cannot be deposited on the masked areas of the metal layer of the metal-ceramic substrate.

[0082] According to a preferred embodiment, the structured metal layer to which the mask is applied also comprises structured areas, particularly preferably structured areas between the primary boundary surface of the metal layer and the primary boundary surface of the ceramic. Therefore, in particular, the areas of the metal layer in the vicinity of the ceramic body are also provided with a mask in order to protect them from dissolution during deposition of the silver-containing layer, in particular when they come into contact with the silver-ion-containing solution in step d).

[0083] To apply the mask, a liquid medium containing a masking agent is applied to specific areas of the structured metal layer and the masking agent is allowed to solidify.

[0084] The liquid medium is preferably a medium that is liquid at room temperature and normal pressure. The liquid medium is preferably a medium that contains a polar solvent, particularly preferably water. According to a preferred embodiment, the liquid medium is selected from the group consisting of a solution and a suspension.

[0085] The liquid medium contains a masking agent. The masking agent is preferably designed to be solidifiable. The masking agent is not further limited. According to a preferred embodiment, the masking agent is curable, particularly UV-curable. The UV-curable masking agent preferably contains at least one compound selected from the group consisting of monomers and oligomers. According to a particularly preferred embodiment, the UV-curable masking agent contains at least one compound selected from the group consisting of acrylates, epoxies, and unsaturated polyester resins. The liquid medium preferably further contains a photoinitiator. The photoinitiator may be, for example, a compound that decomposes upon absorbing UV light to form reactive species that can initiate polymerization and curing of the UV-curable masking agent. In addition, the liquid medium may contain other components such as colorants, additives, etc.

[0086] The liquid medium containing the masking agent is applied to specific areas of the structured metal layer, and for this purpose, the liquid medium is preferably applied to areas of the structured metal layer that are to be masked and protected from the deposition of the silver-containing layer in step d).

[0087] The liquid medium is preferably applied to the structured metal layer by printing, spraying or painting. According to a particularly preferred embodiment, the liquid medium is applied by printing using an inkjet process.

[0088] After applying the liquid medium, the masking agent contained therein is preferably solidified.For this purpose, the masking agent is preferably cured.Curing can be achieved, for example, by irradiating the liquid medium with UV light so that the masking agent (particularly the monomer or oligomer) contained therein is polymerized.

[0089] According to a preferred embodiment, applying a mask to the structured metal layer comprises an additive masking step. The additive masking step refers to the application of a masking agent. According to a further preferred embodiment, applying a mask to the structured metal layer does not comprise a subtractive masking step. The subtractive masking step is understood to mean, in particular, the partial removal of a masking agent applied, for example, in an additive masking step, before depositing a silver-containing layer on the unmasked areas of the structured metal layer in step d) to obtain silver-containing contact areas. According to this preferred embodiment, the liquid medium containing the masking agent is applied only to areas of the structured metal layer on which a silver-containing layer will not be deposited in step d) and, if appropriate, to areas of the ceramic body exposed by recesses in the metal layer that form the structuring. In conventional masking methods, the masking agent is applied to the structured metal layer, preferably as a layer, especially over the entire surface, in an additive masking step, and in a subsequent subtractive masking step, the solidified masking agent is removed in areas of the structured metal layer on which a silver-containing layer will be deposited in the subsequent step. By omitting the subtractive masking step, this preferred embodiment advantageously provides a particularly simple method for producing a metal-ceramic substrate provided with a structuring and a contact area comprising silver.

[0090] According to a preferred embodiment, in step c), a liquid medium containing a masking agent is applied to the areas of the ceramic body exposed by the recesses of the metal layer forming the structure, and the masking agent is allowed to solidify, thereby applying a mask to the areas of the ceramic body exposed by the recesses of the metal layer forming the structure. Applying a mask to the exposed areas of the ceramic body can be advantageous in order to protect the exposed areas of the ceramic body from the deposition of a silver-containing layer in step d).

[0091] The application of the mask to the structured metal layer and to the areas of the ceramic body exposed by the recesses in the metal layer forming the structuring can be carried out simultaneously or sequentially.

[0092] To apply a mask to the areas of the ceramic body exposed by the recesses in the metal layer forming the structured portion, a liquid medium as described above for applying a mask to a structured metal layer and an application as described above for applying a mask to a structured metal layer can be used.

[0093] In step d), a silver-containing layer is deposited on the unmasked areas of the structured metal layer to obtain contact areas comprising silver.

[0094] The silver-containing layer is preferably a layer made of silver or a silver alloy, and particularly preferably a layer made of silver. The deposition of the silver-containing layer is preferably carried out chemically (e.g., electrochemically) or physically. Chemical deposition of the silver-containing layer can be carried out, for example, galvanically or electrolessly. Preferably, chemical deposition of the silver-containing layer is carried out electrolessly by applying a silver-containing solution, resulting in charge exchange between the metals, partially dissolving the metal of the metal layer, while depositing the silver in the solution. According to a preferred embodiment, the silver-containing solution contains a silver salt, particularly preferably silver nitrate. According to a particularly preferred embodiment, the silver-containing solution is an acidic solution of silver nitrate, particularly preferably a nitric acid solution of silver nitrate. The silver concentration in the nitric acid solution can be, for example, in the range of 0.5 to 1.5 g / L, particularly preferably in the range of 0.6 to 1.4 g / L, and very particularly preferably in the range of 0.8 to 1.2 g / L. Physical deposition of the silver-containing layer can be carried out, for example, by vapor deposition. Preferred methods of vapor deposition are in particular electron beam deposition, laser beam deposition, arc discharge deposition or cathodic sputtering.

[0095] In step e), the mask is removed.

[0096] The mask can be removed by standard methods. For this purpose, it can be exposed to an alkaline solution (e.g., 2.5% sodium hydroxide solution). After removing the mask, the metal-ceramic substrate comprises at least one contact area containing silver, and the surface of the metal layer that is not provided with a contact area containing silver is freely accessible.

[0097] The method described herein makes it possible to obtain a metal-ceramic substrate provided with a structuring and a contact area comprising silver. By creating a contact area comprising silver, chips can be more easily bonded to the metal-ceramic substrate using common processes such as sintering or soldering. The metal-ceramic substrate thus obtained is characterized by a particularly high resistance to thermal shock.

[0098] Illustrative Embodiments The invention is explained in more detail below using exemplary embodiments, which should not be understood as limiting.

[0099] Example 1: Example 1a - Preparation of structured metal-ceramic substrate: As Example 1, a metal-ceramic substrate was used in which a ceramic body made of silicon nitride ceramic and having dimensions of 177.8 × 139 × 0.32 mm was bonded to both sides with copper layers having dimensions of 170 × 132 × 0.3 mm using the AMB (active metal brazing) process. This copper-ceramic substrate was first cleaned after production.

[0100] A photosensitive film was then applied to both copper layers of the copper-ceramic substrate using a hot roll laminator. The photosensitive film was then irradiated with 30 mJ / cm2 in each of the masked areas to cure the polymer contained in the photosensitive film and obtain an etching mask. 2 The copper-ceramic substrate was exposed to light with a fluorine-containing solution (fluorine ion content = 160 g / L). The unexposed areas of the photosensitive film were then wet-chemically removed using a sodium carbonate solution (concentration = 10 g / L). After applying the etching mask, the copper-ceramic substrate was rinsed and cleaned. The unmasked areas of the copper layer of the copper-ceramic substrate were then wet-chemically etched. For this purpose, a copper chloride solution (copper ion content = 160 g / L) containing hydrogen peroxide was sprayed onto the copper-ceramic substrate in an etching system. The etching was carried out at a temperature of 50 °C and a spray pressure of 2.8 bar. The etching removed material from the unmasked areas of the copper layer of the copper-ceramic substrate. The copper-ceramic substrate was then rinsed. The unmasked areas of the bonding layer included in the copper-ceramic substrate were then wet-chemically etched as well. For this purpose, an etching solution containing ammonium fluoride, fluoroboric acid, and hydrogen peroxide was sprayed onto the copper-ceramic substrate again in an etching system. The copper-ceramic substrate was then rinsed and dried. The etching mask was then removed using a 2.5% sodium hydroxide solution in a stripping system.

[0101] Example 1b - Preparation of a structured metal-ceramic substrate with a contact area comprising silver: The structured copper-ceramic substrate prepared in Example 1a was provided with contact areas containing silver. For this purpose, a mask was first applied to the structured copper layer of the copper-ceramic substrate (including the structured areas) and to the areas of the ceramic body exposed by the recesses in the copper layer forming the structuring (exposed areas of the ceramic body). For this purpose, the structured copper-ceramic substrate was placed in an inkjet printer (MicroCraft C4K7861T, Sense Advanced Technology GmbH) and a mask was applied to the structured copper layer (including the structured areas) and the exposed areas of the ceramic body. A liquid medium containing a masking agent (DiPaMAT Etch Resist ER02) was then printed onto the silver-free areas of the structured copper layer and the exposed areas of the ceramic body. UV radiation (LED 390 nm, 500 mJ / cm ) was then applied. 2 The masking agent was then cured using a masking agent. The silver-free areas of the structured copper layer and the exposed areas of the ceramic body were thus covered with a 30 μm thick mask.

[0102] Thereafter, a silver-containing contact area was deposited on the unmasked area of the copper layer of the copper-ceramic substrate. For this purpose, the masked copper-ceramic substrate was first pretreated with a first solution containing hydrogen peroxide and sulfuric acid, and then contacted with a nitric acid / silver nitrate solution (silver content = 1.0 g / L). After deposition of the silver-containing contact area, the copper-ceramic substrate was carefully rinsed with water to remove any residue. The mask was then removed using a 2.5% sodium hydroxide solution in a stripping system.

[0103] The resulting copper-ceramic substrate was laser cut into individual parts with dimensions (20.5 x 17.0 mm) which could then be used for further investigation and for the fabrication of electronic components.

[0104] Comparative Example 1: Comparative Example 1a - Preparation of structured metal-ceramic substrate: In Comparative Example 1a, a structured copper-ceramic substrate was prepared similarly to Example 1a.

[0105] Comparative Example 1b - Preparation of a structured metal-ceramic substrate with a contact area containing silver: The structured copper-ceramic substrate prepared in Comparative Example 1a was provided with contact areas containing silver. For this purpose, a mask was first applied to the structured copper layer of the copper-ceramic substrate (including the structured areas) and to the areas of the ceramic body exposed by the recesses in the copper layer forming the structured portions (exposed areas of the ceramic body). For this purpose, a photosensitive film was applied to the two etched surfaces of the structured copper-ceramic substrate using a hot roll laminator. In order to harden the polymer contained in the photosensitive film and obtain the mask, the photosensitive film was applied to each of the masked areas with 30 mJ / cm2. 2 The copper-ceramic substrate was exposed to light with a 1000 Watt Max power supply. The unexposed areas of the photosensitive film were then wet-chemically removed using a sodium carbonate solution (concentration = 10 g / L). After applying the mask, the copper-ceramic substrate was rinsed and cleaned again. Silver-containing contact areas were then deposited on the unmasked areas of the copper layer of the copper-ceramic substrate. For this purpose, the masked copper-ceramic substrate was first pretreated with a first solution containing hydrogen peroxide and sulfuric acid, and then contacted with a nitric acid / silver nitrate solution (silver content = 1.0 g / L). After deposition of the silver-containing contact areas, the copper-ceramic substrate was carefully rinsed with water to remove any residue. The mask was then removed in a stripping system using a 2.5% sodium hydroxide solution.

[0106] The resulting copper-ceramic substrate was laser cut into individual parts with dimensions (20.5 x 17.0 mm) which could then be used for further investigation and for the fabrication of electronic components.

[0107] evaluation: The ratio S(BC) for the copper-ceramic substrates obtained in Example 1 and Comparative Example 1 solid ) / S(BC total) was determined. For this purpose, as described herein, the copper-ceramic substrates were cut perpendicular to the primary interface of each ceramic body, and images of the cross sections thus obtained were captured using an optical microscope. Points A, B, and C were determined on the cross sections. The ratio S(BC) for each of the copper-ceramic substrates was then calculated. solid ) / S(BC total For this purpose, ten different cross sections of the structured area in the copper layer of the corresponding copper-ceramic substrate were examined, and the ratio S(BC solid ) / S(BC total ) for each of these cross sections to obtain the ratio S(BC solid ) / S(BC total ) and calculate the ratio S(BC solid ) / S(BC total The average value of the values was calculated. Furthermore, the standard deviation (SSD) was calculated.

[0108] Similarly, for the copper-ceramic substrates obtained in Example 1 and Comparative Example 1, the silver content of the region adjacent to the upper half of the contour line and the region adjacent to the lower half of the contour line was determined by energy dispersive X-ray spectroscopy (EDX) combined with scanning electron microscopy (SEM) (SEM-EDX) as described above.

[0109] FIG. 4 shows an example of an optical microscope photograph of a cross section of a structured region of the copper layer of a copper-ceramic substrate according to Example 1, and FIG. 5 shows an example of an optical microscope photograph of a cross section of a structured region of the copper layer of a copper-ceramic substrate according to Comparative Example 1.

[0110] The results are shown in Table 1.

[0111] [Table 1]

[0112] The thermal shock resistance of the copper-ceramic substrate was tested. For this purpose, a thermal shock resistance test was carried out.

[0113] Thermal shock resistance test: In preparation for the thermal shock resistance test, we first used an ultrasonic microscope (PVA Tepla SAM300) to confirm the integrity of the copper-ceramic substrate. Only copper-ceramic substrates that showed no delamination between the ceramic body and the copper layer or other deformations (e.g., cracks) that could result in delamination of the copper layer from the ceramic body were used for the test. To test thermal shock resistance, the copper-ceramic substrates were repeatedly exposed to cold liquid (temperature -65°C, Galden Do2TS) and hot liquid (temperature +150°C, Galden Do2TS) for 5 minutes each in a cycle chamber (ESPEC TSB-2151). The copper-ceramic substrates were rechecked for delamination and other deformations every 1000 cycles using the ultrasonic microscope (PVA Tepla SAM300). The test was terminated after 3000 cycles. The copper-ceramic substrates were then re-examined for delamination and other deformations using the ultrasonic microscope (PVA Tepla SAM300). The state of each copper-ceramic substrate after the thermal shock resistance test was compared with the state of the copper-ceramic substrate before the thermal shock resistance test for delamination and other deformations. Delamination and other deformations (e.g., cracks) were visible as white discolorations in the ultrasound images.

[0114] The results are shown in Table 2.

[0115] [Table 2]

[0116] The results show that the metal-ceramic substrate according to the present invention is clearly superior to the metal-ceramic substrate of Comparative Example 1 in terms of thermal shock resistance. [Explanation of symbols]

[0117] 1 Metal-ceramic substrate 4 Structured area 8 Contact area 10 ceramic body 15 Primary interface of ceramic body 20 metal layer 22 recess 24 Primary interface of metal layer 40 Contour Lines 50 solid materials 60 Silver 200 More Metal Layers

Claims

1. A metal-ceramic substrate, a) a ceramic body having a primary boundary surface; b) a metal layer having a primary interface, said metal layer being connected to said ceramic body at a surface thereof, said metal layer comprising: (i) partially comprised of solid material; (ii) a metal layer with structured regions partially comprising a non-solid material; c) a contact region comprising silver and disposed on the metal layer, In a cross section through the metal-ceramic substrate perpendicular to the primary interface of the ceramic body, the structured region has a geometric shape that satisfies the following requirements: S(BC ｓｏｌｉｄ ) / S(BC ｔｏｔａｌ )>60% During the ceremony, S (BC ｔｏｔａｌ ) means the total length of the line between points B and C, S (BC ｓｏｌｉｄ ) means the length of the line between points B and C that intersects the solid material; Points B and C are determined as follows:

1. A best fit line between the ceramic body and the metal layer is determined; 2. A contour line separating the solid material from the non-solid material is determined; 3. A point A where a perpendicular to the best fit line intersects the contour line is determined on the perpendicular to the best fit line at a distance of 150 μm from the best fit line; 4. A point B where a perpendicular to the best fit line intersects the contour line is determined on the perpendicular to the best fit line at a distance of 80 μm from the best fit line; 5. A point C is determined on a line passing through points A and B where said line intersects with said line of best fit; a contour line extending from the primary boundary surface of the metal layer to the primary boundary surface of the ceramic body, the contour line having an upper half and a lower half, the upper half of the contour line extending from the primary boundary surface of the metal layer toward the primary boundary surface of the ceramic body, and the lower half of the contour line extending from the primary boundary surface of the ceramic body toward the primary boundary surface of the metal layer, and the solid material in a region adjacent the upper half of the contour line has a higher silver content than a region adjacent the lower half of the contour line.

2. 2. The metal-ceramic substrate of claim 1, wherein the ceramic of the ceramic body is selected from the group consisting of aluminum nitride ceramic, silicon nitride ceramic, and aluminum oxide ceramic.

3. 3. The metal-ceramic substrate according to claim 1, wherein the metal layer comprises copper.

4. The metal-ceramic substrate according to any one of claims 1 to 3, characterized in that the solid material contains the metal of the metal layer.

5. The metal-ceramic substrate according to any one of claims 1 to 4, characterized in that the non-solid material comprises a gas-phase material.

6. Meet the following requirements: S(BC ｓｏｌｉｄ ) / S(BC ｔｏｔａｌ )>95% The metal-ceramic substrate according to any one of claims 1 to 5, characterized in that:

7. The ratio S(BC ｓｏｌｉｄ ) / S (BC ｔｏｔａｌ 7. The metal-ceramic substrate according to claim 1, wherein the sample standard deviation SSD of the above is 10% or less.

8. 8. The metal-ceramic substrate according to claim 1, wherein the ratio of the silver content of the solid material in the region adjacent to the upper half of the contour line to the silver content of the solid material in the region adjacent to the lower half of the contour line is less than 0.

8.

9. An electronic component comprising the metal-ceramic substrate according to any one of claims 1 to 8.

10. 1. A method for producing a metal-ceramic substrate provided with a structure and a contact area comprising silver, the method comprising: a) providing a metal-ceramic substrate, the metal-ceramic substrate comprising: a1) a ceramic body; a2) a metal layer connected to the ceramic body at a surface thereof; b) structuring said metal layer; c) applying a mask to the structured metal layer by applying a liquid medium containing a masking agent to specific areas of the structured metal layer and allowing the masking agent to solidify; d) depositing a silver-containing layer on the unmasked areas of said structured metal layer to obtain contact areas comprising silver; e) removing the mask; A method comprising:

Images