Metal-ceramic substrate, its manufacturing method and module

Abstract

The present invention relates to a metal-ceramic substrate. The problem addressed is to provide a metal-ceramic substrate having a very stable bond between the metal layer and the ceramic body, and also high thermal and electrical conductivity. The metal-ceramic substrate comprises (a) a ceramic body, (b) a metal layer, and (c) a bonding layer located between the ceramic body and the metal layer. The bonding layer comprises (i) a metal M1 having a melting point of at least 700° C., (ii) a metal M2 having a melting point of less than 700° C., (iii) a metal M3 selected from the group of active metals, and (iv) a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium. The bonding layer has the following properties: (c1) M(M2) EDX =10~20wt%, (c2)15wt%≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦100% by weight, and (c3) M(Ag) EDX <10% by weight.

Description

[Technical Field]

[0001] The present invention relates to a metal-ceramic substrate, a method for manufacturing a metal-ceramic substrate, and a module having a metal-ceramic substrate.

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

[0003] Several methods for bonding a metal layer to a ceramic layer are known in 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 thus treated copper foil is applied to a ceramic body and the composite is fired, 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] Despite its clear advantages, the DCB method has two major disadvantages. First, the method must be performed at relatively high temperatures, i.e., slightly below the melting point of copper. Second, the method can only be used with oxide-based ceramics, such as aluminum oxide or superficially oxidized aluminum nitride. Therefore, there is a need for an alternative method for producing metal-ceramic substrates under less stringent conditions. In this alternative method, metal foils can be bonded to ceramic bodies at temperatures of approximately 650-1000°C using a specific solder 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 bonding of the ceramic material to the remaining solder and forming a reaction layer, while the metal with a melting point of at least 700°C serves to bond the reaction layer to the metal foil. For example, Japanese Patent No. 4812985(B2) proposes joining copper foil to a ceramic body using a solder containing 50-89% by weight of silver, copper, bismuth, and an active metal, which allows the copper foil to be stably attached to the ceramic body.

[0005] To avoid problems associated with silver migration, it may be advantageous to use silver-free solders to bond 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 German Patent Application Publication No. 102017114893 (A1). This technique essentially creates a new, independent class of compounds, since the basis of the solder used is formed by another metal (copper instead of silver), leading to changes in material properties and compatibility with other solder components and modified bonding conditions. Thus, the metal-ceramic substrates produced in this way contain, in addition to the metal layer and the ceramic body, a bonding layer between the metal layer and the ceramic body containing the active metal.

[0006] The ever-increasing requirements in the field of power electronics have also led to increased requirements for the stability of the bond between the metal layer and the ceramic body in a metal-ceramic substrate, as well as the thermal and electrical conductivity of the metal-ceramic substrate. It has been found that the stability of the bond between the metal layer and the ceramic body increases with an increase in the content of low-melting-point metal in the bonding layer. However, as the content of low-melting-point metal in the bonding layer increases, the problem of increased diffusion of the low-melting-point metal into the metal layer of the metal-ceramic substrate increases. This effect reduces the thermal and electrical conductivity of the metal-ceramic substrate. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, there is a need for a metal-ceramic substrate that includes, on the one hand, a very stable bond between the metal layer and the ceramic body, and, on the other hand, high thermal and electrical conductivity. There is also a need for such a metal-ceramic substrate that is at least largely free of silver to avoid the problems associated with silver migration.

[0008] It is therefore an object of the present invention to provide a metal-ceramic substrate which, on the one hand, comprises a very stable bond between the metal layer and the ceramic body, and, on the other hand, has high thermal and electrical conductivity. It is therefore a further object of the present invention to provide such a metal-ceramic substrate which does not have the problems associated with silver migration.

[0009] These objects are achieved by a metal-ceramic substrate according to claim 1. The invention therefore provides: (a) a ceramic body; (b) a metal layer; (c) a bonding layer positioned between the ceramic body and the metal layer, (i) a metal M1 having a melting point of at least 700°C; (ii) a metal M2 having a melting point below 700°C; (iii) a metal M3 selected from the group of active metals, and (iv) a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium a bonding layer including: A metal-ceramic substrate comprising: The bonding layer has the following properties: (c1)M(M2) EDX =10~20% by weight, (c2)15% by weight≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦100% by weight, and (c3) M(Ag) EDX <10% by weight characterized in that it has During the ceremony, M(M2) EDX is the metal M2 content in the bonding layer, determined using EDX, [M(M4) / M(M2)] ICP is the gold content in the bonding layer, determined using ICP. genus M2 content The content of metal M4 in the bonding layer is the ratio, M(Ag) EDX is the silver content in the bonding layer determined using EDX, A metal-ceramic substrate is provided.

[0010] The present invention further provides a method for manufacturing a metal-ceramic substrate and a module having a metal-ceramic substrate.

[0011] The metal-ceramic substrate according to the present invention comprises a ceramic body, a metal layer, and a bonding layer.

[0012] In a metal-ceramic substrate, the bonding layer is located between the ceramic body and the metal layer. Therefore, the bonding layer is preferably in contact with the ceramic body and the metal layer. According to a preferred embodiment, the metal-ceramic substrate includes a ceramic body, a (first) metal layer, a (first) bonding layer in contact with the ceramic body and the first metal layer, a second metal layer, and a second bonding layer in contact with the ceramic body and the second metal layer. According to this embodiment, the (first) bonding layer is preferably located between the ceramic body and the (first metal) layer, and the second bonding layer is preferably located between the ceramic body and the second metal layer. Furthermore, according to this embodiment, the composition of the first bonding layer preferably corresponds to the composition of the second bonding layer.

[0013] The ceramic body preferably comprises a first surface and a second surface. The metal layer preferably comprises the first surface. The second metal layer, if present, preferably comprises the first surface. According to a preferred embodiment, a (first) bonding layer is located within the metal-ceramic substrate between the first surface of the ceramic body and the first surface of the (first) metal layer. According to a further preferred embodiment, the metal-ceramic substrate comprises a second bonding layer in contact with the second surface of the ceramic body and the first surface of the second metal layer. According to this embodiment, the (first) bonding layer is preferably located within the metal-ceramic substrate between the first surface of the ceramic body and the first surface of the (first) metal layer, and the second bonding layer is preferably located between the second surface of the ceramic body and the first surface of the second metal layer. According to a further preferred embodiment, in addition to the bonding layer according to the present invention, no further layer is located between the ceramic body and the (first) metal layer. According to yet another embodiment, in addition to the bonding layer according to the present invention, no further layer is located between the ceramic body and the second metal layer, if present.

[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 more 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) "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 0.1 to 5 mm, and particularly preferably 0.15 to 3 mm.

[0016] The metal of the metal layer is preferably selected from the group consisting of copper, aluminum, and molybdenum. According to a particularly preferred embodiment, the metal of the metal layer is selected from the group consisting of copper and molybdenum. According to a very particularly preferred embodiment, the metal of the metal layer is copper. According to a further very particularly preferred embodiment, the metal layer consists of copper and unavoidable impurities.

[0017] The metal layer preferably has a thickness in the range from 0.01 to 10 mm, particularly preferably in the range from 0.03 to 5 mm, very particularly preferably in the range from 0.05 to 3 mm.

[0018] The bonding layer includes (i) a metal M1 having a melting point of at least 700°C, (ii) a metal M2 having a melting point less than 700°C, (iii) a metal M3 selected from the group of active metals, and (iv) a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium.

[0019] A bonding layer is preferably understood to mean the region of the metal-ceramic substrate which is located between the ceramic body and the metal layer.

[0020] The bonding layer comprises (i) a metal M1 having a melting point of at least 700°C. The metal M1 having a melting point of at least 700°C preferably has a melting point of at least 850°C, and particularly preferably has a melting point of at least 1000°C. According to a preferred embodiment, the metal M1 having a melting point of at least 700°C is selected from the group consisting of copper, nickel, tungsten, and molybdenum. According to a particularly preferred embodiment, the metal M1 having a melting point of at least 700°C is copper.

[0021] The bonding layer (ii) comprises a metal M2 having a melting point of less than 700° C. The metal M2 having a melting point of less than 700° C. preferably has a melting point of less than 600° C., particularly preferably has a melting point of less than 550° C. According to a particularly preferred embodiment, the metal M2 having a melting point of less than 700° C. is tin.

[0022] The bonding layer comprises (iii) a metal M3 selected from the group of active metals. Therefore, the metal M3 is preferably a metal that forms a bond with the ceramic by chemical reaction. According to a preferred embodiment, the metal M3 is selected from the group consisting of hafnium, titanium, zirconium, niobium, cerium, tantalum, and vanadium. According to a more preferred embodiment, the metal M3 is selected from the group consisting of hafnium, titanium, zirconium, niobium, and cerium. According to a particularly preferred embodiment, the metal M3 is selected from the group consisting of hafnium, titanium, and zirconium. According to a very particularly preferred embodiment, the metal M3 is titanium.

[0023] The bonding layer (iv) comprises a metal M4. The metal M4 is a metal selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium. According to a particularly preferred embodiment, the metal M4 is selected from the group consisting of bismuth, gallium, and zinc. According to a very particularly preferred embodiment, the metal M4 is bismuth.

[0024] The metals M1, M2, M3, and M4 are different metals. Thus, the bonding layer positioned between the ceramic body and the metal layer includes each of the metals M1, M2, M3, and M4. Thus, the bonding layer positioned between the ceramic body and the metal layer includes (i) a metal M1 having a melting point of at least 700°C, (ii) a metal M2 having a melting point less than 700°C, (iii) a metal M3 selected from the group of active metals, and (iv) a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, wherein the metals M1, M2, M3, and M4 are different. Thus, the metal M2 having a melting point less than 700°C is not selected from the group consisting of bismuth, gallium, zinc, indium, aluminum, and magnesium. Furthermore, the metal M2 is not an active metal. Similarly, the metal M1 having a melting point of at least 700°C is not germanium. Furthermore, the metal M1 having a melting point of at least 700°C is not an active metal.

[0025] According to the invention, the bonding layer has the following properties: (c1)M(M2) EDX =10~20% by weight, (c2)15% by weight≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦100% by weight, and (c3) M(Ag) EDX <10% by weight and During the ceremony, M(M2) EDX is the content [wt%] of metal M2 in the bonding layer, determined using EDX; [M(Bi) / M(M2)] ICP is the gold content in the bonding layer, determined using ICP. genus M2 content The content of metal M4 in the bonding layer is the ratio, M(Ag) EDX is the silver content [wt %] in the bonding layer, determined using EDX.

[0026] According to the characteristic (c1), the content of metal M2 in the bonding layer, determined using EDX, is 10-20 wt. %. According to a preferred embodiment, the bonding layer has the following characteristics: (c1')M(M2) EDX =10~18wt% It has.

[0027] According to a particularly preferred embodiment, the bonding layer has the following properties: (c1'')M(M2) EDX =10~15% by weight It has.

[0028] According to the property (c2), there is a relationship between the content of metal M4 and the content of metal M2, so that the bonding layer has the following property: (c2)15% by weight≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦100% by weight It has.

[0029] According to a preferred embodiment, the bonding layer has the following properties: (c2'):15wt%≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦80% by weight It has.

[0030] According to a particularly preferred embodiment, the bonding layer has the following properties: (c2''):15% by weight≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦70% by weight It has.

[0031] It has been surprisingly found that the amount of metal M2, which has a melting point below 700°C and is necessary for a particularly stable bond between the ceramic body and the metal layer, can be reduced by adding a small amount of metal M4, without impairing the electrical and thermal conductivity of the metal-ceramic substrate due to diffusion of metal M2 into the metal layer. Furthermore, it has been surprisingly found that a particularly stable bond is achieved when the content of metal M2 in the bonding layer is within a specified range. The relationship between the proportions of metals M2 and M4 in the bonding layer necessary for this effect is represented by properties (c1) and (c2). Thus, surprisingly, by adjusting the content of metal M2, which has a melting point below 700°C, and the content of metal M4, which is selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, a metal-ceramic substrate is provided that has a particularly stable bond between the ceramic body and the metal layer, on the one hand, and high electrical and thermal conductivity, on the other hand.

[0032] According to property (c3), the silver content in the bonding layer is 10 wt % or less as determined using EDX. Thus, the present invention also includes embodiments in which the bonding layer does not contain silver, i.e., the silver content in the bonding layer is 0 wt % as determined using EDX.

[0033] According to a particularly preferred embodiment, the bonding layer has the following properties: (c3')M(Ag) EDX <5% by weight It has.

[0034] According to a very particularly preferred embodiment, the bonding layer has the following properties: (c3'')M(Ag) EDX <1% by weight It has.

[0035] The absence of silver or the presence of only small amounts of silver means that unwanted migration of silver at the edges of the bonding layer within the metal-ceramic substrate can be avoided or reduced.

[0036] According to a preferred embodiment, the content of metal M1 in the bonding layer (M(M1) EDX ) is in the range of 65 to 89 wt %. According to a particularly preferred embodiment, the content of the metal M1 in the bonding layer (M(M1) EDX ) is in the range of 67 to 88% by weight. According to a very particularly preferred embodiment, the content of the metal M1 in the bonding layer (M(M1)) determined by means of EDX EDX ) is in the range of 70 to 88% by weight.

[0037] According to a preferred embodiment, the content of metal M3 in the bonding layer (M(M3)) determined using EDX EDX ) is in the range of 0.5 to 15 wt %. According to a particularly preferred embodiment, the content of the metal M3 in the bonding layer (M(M3)) determined by EDX is EDX ) is in the range of 0.5 to 14% by weight. According to a very particularly preferred embodiment, the content of the metal M3 in the bonding layer, determined by means of EDX (M(M3) EDX ) is in the range of 1 to 14% by weight.

[0038] According to a preferred embodiment, the content of metal M4 in the bonding layer (M(M4)) determined using ICP is ICP) is in the range of 0.01 to 2 wt %. According to a particularly preferred embodiment, the content of the metal M4 in the bonding layer (M(M4)) determined by ICP is ICP ) is in the range of 0.01 to 1.5% by weight. According to a very particularly preferred embodiment, the content of metal M4 in the bonding layer (M(M4)) determined by means of ICP ICP ) is in the range of 0.1 to 1% by weight.

[0039] Metal-ceramic substrates according to the present invention can be manufactured by methods that constitute standard practice in the art.

[0040] According to a preferred embodiment, the method for producing a metal-ceramic substrate according to the invention comprises the steps of: a) a laminate, a1) a ceramic body; a2) a metal foil; a3) a solder material in contact with the ceramic body and the metal foil, (i) a metal M1 having a melting point of at least 700°C; (ii) a metal M2 having a melting point below 700°C; (iii) a metal M3 selected from the group of active metals, and (iv) a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium a solder material comprising: providing a laminate comprising: b) heating the laminate to obtain a metal-ceramic substrate; Includes.

[0041] Thus, first, a laminate is preferably provided that includes a ceramic body, a metal foil, and a solder material in contact with the ceramic body and the metal foil.

[0042] Therefore, in the laminate, the solder material is preferably located between the ceramic body and the metal foil. According to a preferred embodiment, the laminate comprises a ceramic body, a (first) metal foil, a (first) solder material in contact with the ceramic body and the first metal foil, a second metal foil, and a second solder material in contact with the ceramic body and the second metal foil. According to this embodiment, the (first) solder material is preferably located between the ceramic body and the (first) metal foil, and the second solder material is preferably located between the ceramic body and the second metal foil. Furthermore, according to this embodiment, the first solder material preferably corresponds to the second solder material.

[0043] The ceramic body, the metal foil and the solder material are preferably designed so that after heating a metal-ceramic substrate according to the invention is produced.

[0044] Therefore, the ceramic body and metal foil are preferably designed as described above for the ceramic body and metal layer of the metal-ceramic substrate.

[0045] The solder material preferably comprises (i) a metal M1 having a melting point of at least 700° C., (ii) a metal M2 having a melting point less than 700° C., (iii) a metal M3 selected from the group of active metals, and (iv) a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium. Metals M1, M2, M3, and M4 are preferably designed as described above for the bonding layer of a metal-ceramic substrate.

[0046] Thus, metals M1, M2, M3, and M4 are different metals. Thus, the solder material in contact with the ceramic body and the metal layer includes each of metals M1, M2, M3, and M4. Thus, the solder material in contact with the ceramic body and the metal layer includes: (i) metal M1 having a melting point of at least 700°C; (ii) metal M2 having a melting point less than 700°C; (iii) metal M3 selected from the group of active metals; and (iv) metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, wherein metals M1, M2, M3, and M4 are different. Thus, metal M2 having a melting point less than 700°C is not selected from the group consisting of bismuth, gallium, zinc, indium, aluminum, and magnesium. Furthermore, metal M2 is not an active metal. Similarly, metal M1 having a melting point of at least 700°C is not germanium. Furthermore, metal M1 having a melting point of at least 700°C is not an active metal.

[0047] According to a preferred embodiment, (i) metal M1, (ii) metal M2, (iii) metal M3, and (iv) metal M4 are present as constituents of at least one metal component. Thus, the solder material preferably includes at least one metal component including (i) metal M1, (ii) metal M2, (iii) metal M3, and (iv) metal M4. For example, it may be preferable for the solder material to include metal component (i) containing metal M1, metal component (ii) containing metal M2, metal component (iii) containing metal M3, and metal component (iv) containing metal M4. Furthermore, the solder material includes a metal component (i) containing a member from the group consisting of (i) metal M1, (ii) metal M2, (iii) metal M3, and (iv) metal M4, and at least one additional metal component (ii) containing a member from the group consisting of (i) metal M1, (ii) metal M2, (iii) metal M3, and (iv) metal M4, which may be preferred not to be contained in the metal component (i). The term "metal component" is not further limited. In addition to metals and metal alloys, it also includes metal compounds such as intermetallic phases and other compounds (e.g., metal hydrides). Thus, according to a preferred embodiment, the metal component is selected from the group consisting of metals, metal alloys, and metal compounds.

[0048] The solder material preferably comprises (i) a metal M1 having a melting point of at least 700°C. According to a preferred embodiment, the solder material comprises a metal component (i) containing a metal M1 having a melting point of at least 700°C. According to a particularly preferred embodiment, the solder material comprises a metal component (i) containing copper. According to a further preferred embodiment, the metal component (i) is copper.

[0049] The solder material preferably includes (ii) a metal M2 having a melting point of less than 700°C. According to a preferred embodiment, the solder material includes a metal component (ii) containing the metal M2 having a melting point of less than 700°C. According to a particularly preferred embodiment, the metal component (ii) is an alloy of the metal M2 having a melting point of less than 700°C with an additional metal. The additional metal can be selected from the group consisting of a metal M1 having a melting point of less than 700°C, a metal M2 having a melting point of at least 700°C, a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, indium, germanium, gallium, and zinc. According to a further preferred embodiment, the metal component (ii) containing the metal M2 having a melting point of less than 700°C is selected from the group consisting of tin, a tin-copper alloy, a tin-bismuth alloy, a tin-antimony alloy, a tin-zinc-bismuth alloy, and an indium-tin alloy.

[0050] The solder material preferably comprises a metal M3 selected from the group of active metals. According to a preferred embodiment, the solder material comprises a metal component (iii) containing a metal M3 selected from the group of active metals. According to a particularly preferred embodiment, the metal component (iii) is an active metal alloy or an active metal compound, particularly preferably an active metal hydride. The metal component (iii) is preferably selected from the group consisting of titanium hydride, titanium-zirconium-copper alloy, zirconium hydride, and hafnium hydride. According to a particularly preferred embodiment, the metal component (iii) is selected from the group consisting of hafnium hydride, titanium hydride, and zirconium hydride. According to a very particularly preferred embodiment, the metal component (iii) is titanium hydride.

[0051] The solder material preferably comprises a metal M4. According to a preferred embodiment, the solder material comprises a metal component (iv) containing a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium. According to a particularly preferred embodiment, the solder material comprises a metal component (iv) containing bismuth. According to a further preferred embodiment, the metal component (iv) is bismuth.

[0052] According to a preferred embodiment, the proportion of metal M1 having a melting point of at least 700°C is 65 to 89% by weight, particularly preferably 67 to 88% by weight, and very particularly preferably 70 to 88% by weight, based on the total metal weight of the solder material. According to a further preferred embodiment, the proportion of metal M2 having a melting point below 700°C is 10 to 20% by weight, particularly preferably 10 to 18% by weight, and very particularly preferably 10 to 15% by weight, based on the total metal weight of the solder material. According to yet another preferred embodiment, the proportion of metal M3 selected from the group of active metals is 0.5 to 15% by weight, particularly preferably 0.5 to 14% by weight, and very particularly preferably 1 to 14% by weight, based on the total metal weight of the solder material. According to a further preferred embodiment, the proportion of the metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium is 0.01 to 2 wt. %, particularly preferably 0.01 to 1.5 wt. %, and very particularly preferably 0.1 to 1 wt. % based on the total metal weight of the solder material. The solder material is preferably silver-free or silver-poor. The silver proportion is therefore preferably less than 10 wt. %, particularly preferably less than 5 wt. %, and very particularly preferably less than 1 wt. % based on the total metal weight of the solder material.

[0053] The solder material is in contact with the ceramic body and the metal foil. Therefore, the solder material is preferably located between the ceramic body and the metal foil. For example, the solder material may be applied to the ceramic body, followed by application of the metal foil. The solder material is preferably at least one material selected from the group consisting of pastes, foils, and deposits containing a metal M1 having a melting point of at least 700°C, a metal M2 having a melting point less than 700°C, a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium.

[0054] The solder material may be a paste, preferably comprising (a) at least one metal component including a metal M1 having a melting point of at least 700°C, a metal M2 having a melting point less than 700°C, a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, and (b) an organic medium.

[0055] The organic medium is preferably an organic medium commonly used in the related technical field, and preferably contains an organic binder, an organic dispersant, or a mixture thereof.

[0056] The organic binder is preferably removed from the solder material during heating. The organic binder is preferably a thermoplastic or thermosetting material. Examples of organic binders include cellulose derivatives (such as ethyl cellulose, butyl cellulose, and cellulose acetate), polyethers (such as polyoxymethylene), and acrylic resins (such as polymethyl methacrylate and polybutylene methacrylate).

[0057] The organic dispersant is preferably an organic compound that imparts an appropriate viscosity to the paste and is released during drying or heating of the paste.The organic dispersant can be selected from, for example, aliphatic alcohols, terpene alcohols, alicyclic alcohols, aromatic cyclic carboxylic acid esters, alicyclic esters, carbitol, and aliphatic polyols.Examples of organic dispersants include octanol, decanol, terpineol (e.g., dihydroterpineol), cyclohexanol, dibutyl phthalate, carbitol, ethyl carbitol, ethylene glycol, butanediol, and glycerol.

[0058] The paste may further contain additives used in standard practice in the art, examples of which include inorganic binders (such as glass frit), stabilizers, surfactants, dispersants, rheology modifiers, wetting aids, defoamers, fillers, and hardeners.

[0059] According to a preferred embodiment, the proportion of at least one metal component including metal M1 having a melting point of at least 700°C, metal M2 having a melting point below 700°C, metal M3 selected from the group of active metals, and metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium is 20 to 95 wt%, more preferably 30 to 95 wt%, particularly preferably 75 to 95 wt%, based on the total weight of the paste. According to a further preferred embodiment, the proportion of the organic medium is 5 to 80 wt%, more preferably 5 to 70 wt%, particularly preferably 5 to 25 wt%, based on the total weight of the paste.

[0060] According to a further preferred embodiment, the ratio of the total weight of (a) at least one metal component, including a metal M1 having a melting point of at least 700 ° C, a metal M2 having a melting point below 700 ° C, a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, to (b) the weight of the organic medium is at least 5: 1, particularly preferably at least 7: 1, and very particularly preferably at least 8: 1. According to a preferred embodiment, the ratio of the total weight of (a) at least one metal component, including a metal M1 having a melting point of at least 700 ° C, a metal M2 having a melting point below 700 ° C, a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, to (b) the weight of the organic medium is in the range of 1: 1 to 20: 1, particularly preferably in the range of 2: 1 to 20: 1, and particularly preferably in the range of 5: 1 to 15: 1.

[0061] To prepare the laminate, the paste is preferably applied to the surface of the ceramic body. The paste can be applied, for example, by a dispersion method or a printing method. Suitable printing methods include, for example, a screen printing process, an inkjet printing method, and an offset printing process. Preferably, the paste is applied to the surface of the ceramic body by a screen printing method.

[0062] After application of the paste, the paste can be pre-dried as needed. Pre-drying can be carried out at room temperature or at an elevated temperature. The pre-drying conditions can vary depending on the organic medium contained in the paste. The pre-drying temperature may be, for example, within the range of 50 to 180°C, and preferably within the range of 80 to 150°C. Pre-drying is usually carried out for 2 minutes to 2 hours, preferably for 5 minutes to 1 hour.

[0063] The paste is then applied to the surface of the metal foil and, if necessary, pre-dried to obtain a laminate.

[0064] The solder material may be a film.

[0065] The film comprises a metal M1 having a melting point of at least 700° C., a metal M2 having a melting point below 700° C., a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium. Additionally, the film may comprise further components, such as, for example, a suitable binder.

[0066] The film can be obtained by, for example, optionally homogenizing at least one metal component comprising a metal M1 having a melting point of at least 700° C., a metal M2 having a melting point below 700° C., a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, and by heating the additional component to a temperature below the melting points of the metal M1 having a melting point of at least 700° C., the metal M2 having a melting point below 700° C., the active metal M3, and the metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, but sufficient to form a bond between the metals. This temperature can be, for example, at least 200° C.

[0067] Alternatively, the film can be obtained by mixing at least one metal component including, for example, a metal M1 having a melting point of at least 700° C., a metal M2 having a melting point less than 700° C., a metal M3 selected from the group of active metals, and a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, with a binder, forming and heating the mixture to form a compact. During heating, the binder can harden and form a matrix in which the metals are distributed.

[0068] To prepare the laminate, the film can be placed, for example, on a ceramic, and then a surface of a metal foil can be applied to the film located on the ceramic to obtain the laminate.

[0069] According to a further embodiment, the solder material can be a deposit. The solder material deposit can be produced, for example, by galvanic deposition or vapor deposition. Preferably, the solder material deposit is produced on a ceramic body. A metal foil can then be applied to the solder material deposited on the ceramic to obtain a laminate.

[0070] The laminate is heated to obtain a metal-ceramic substrate. According to a preferred embodiment, heating is performed to obtain a metal-ceramic substrate with a solder material that forms a cohesive bond between the ceramic body and the metal foil. The cohesive bond is preferably formed by joining a metal M3 to the ceramic body during heating, with the metal M1 having a melting point of at least 700°C, the metal M2 having a melting point of less than 700°C, the metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, and the metal of the metal foil being joined to form an alloy. During subsequent solidification, a cohesive bond is formed between the ceramic body and the metal foil via the active metal M3 that is joined to the ceramic body and the resulting alloy.

[0071] During heating, the laminate is heated to a peak temperature. The peak temperature is not limited to a specific value, but is preferably at least 10°C below the melting point of the metal M1, which has a melting point of at least 700°C, and lower than the melting point of the metal of the metal foil. According to a preferred embodiment, the peak temperature is at least 10°C, particularly preferably at least 50°C, below the melting point of the metal of the metal foil. According to a further preferred embodiment, the peak temperature is at least 700°C. The peak temperature is preferably in the range of 700 to 1100°C, particularly preferably in the range of 750 to 1050°C, and very particularly preferably in the range of 800 to 1000°C. The peak temperature, as used herein, refers to the temperature measured at the laminate by a thermocouple. The peak temperature is the maximum temperature measured at the laminate. To prevent adverse effects, such as excessive shrinkage or swelling of the molten metal due to excessive fluidity of the molten metal, those skilled in the art strive to avoid excessively high peak temperatures.

[0072] During heating, the laminate is supplied with heat for a high-temperature heating period. The high-temperature heating period in this specification preferably refers to the period during which the laminate is exposed to a temperature at least equal to a peak temperature of 250°C. Thus, for an exemplary peak temperature of 900°C, the high-temperature heating period corresponds to the period during which the laminate is exposed to a temperature of at least 650°C during heating. According to a preferred embodiment, the high-temperature heating period is 60 minutes or less, more preferably 50 minutes or less, particularly preferably 45 minutes or less, and very particularly preferably 40 minutes or less. The high-temperature heating period is preferably in the range of 2 to 60 minutes, more preferably in the range of 3 to 50 minutes, particularly preferably in the range of 5 to 45 minutes, and very particularly preferably in the range of 10 to 40 minutes.

[0073] The laminate is preferably heated with the necessary energy input in the direction of the laminate starting from the heating zone. The cohesive bond is preferably formed by bonding a metal M3 to the ceramic body, the metal M4 being selected from the group consisting of metal M1 having a melting point of at least 700°C, metal M2 having a melting point below 700°C, metal M4 having a melting point below 700°C, bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, and the metal of the metal foil to form an alloy. During subsequent solidification, a cohesive bond is formed between the ceramic body and the metal foil via the active metal M3 bonded to the ceramic body and the alloy.

[0074] According to a particularly preferred embodiment, the laminate is heated in an oven, preferably in a continuous furnace or a chamber furnace.

[0075] A non-oxidizing atmosphere is preferably present in the heating zone. The non-oxidizing atmosphere is preferably an inert gas atmosphere. A nitrogen atmosphere, a helium atmosphere, or an argon atmosphere is preferably present in the heating zone. According to a particularly preferred embodiment, a nitrogen atmosphere is present in the heating zone. The proportion of reactive gases, in particular oxygen, in the non-oxidizing atmosphere is preferably less than 1000 ppm, more preferably less than 500 ppm, and particularly preferably less than 40 ppm.

[0076] When the laminate is heated, a cohesive bond is preferably formed between the ceramic body and the metal foil via the solder material to obtain a metal-ceramic substrate including the ceramic body, the metal layer, and a bonding layer located between the ceramic body and the metal layer. If necessary, the metal-ceramic substrate can be subjected to further processing steps. For example, the exposed surface of the metal-ceramic substrate, preferably the metal layer of the metal-ceramic substrate, can be polished. Preferably, the surface of the metal layer of the metal-ceramic substrate is physically or chemically polished. Further metal-ceramic substrates can be constructed. For example, the metal-ceramic substrate can be provided with conductor traces. The conductor traces are preferably produced by etching.

[0077] The metal-ceramic substrate according to the invention can be used in particular for applications in electronics, especially in the field of power electronics.

[0078] Therefore, the present invention also provides a module having the above-described metal-ceramic substrate.

[0079] According to a preferred embodiment, such a module comprises a base plate, preferably extensively bonded to a metal layer of the metal-ceramic substrate. According to a further preferred embodiment, the module comprises at least one chip, preferably extensively bonded to a metal layer of the at least one metal-ceramic substrate. According to a further preferred embodiment, the module comprises a metal-ceramic substrate comprising a first metal layer and a second metal layer (the first metal layer preferably opposite the second metal layer), a base plate, and at least one chip, wherein the at least one chip is bonded to the first metal layer of the metal-ceramic substrate and the base plate is bonded to the second metal layer of the metal-ceramic substrate.

[0080] The properties of the metal-ceramic substrate bond layer are preferably determined using the measurement methods described below.

[0081] Measurement method: (i) The content of metals M1, M2, M3 and silver in the bonding layer (characteristic M(M1) EDX , M(M2) EDX , M(M3) EDX and M(Ag) EDX ) is determined by: The content of metals M1, M2, M3 and silver in the bonding layer is preferably determined as follows.

[0082] In the first step, a 100 mm sample is taken from the metal-ceramic substrate to be inspected. 2 ~400mm 2A rectangular sample blank with a rectangular base in the range of 1 / 3 was cut out by sawing a diamond saw blade at a low rotational speed with an oil-based lubricant (Buehler) perpendicular to the plane of the metal layer of the metal-ceramic substrate. Thus, the sample blank had a sample surface to be subjected to testing. This sample surface therefore extended perpendicular to the plane of the metal layer of the metal-ceramic substrate before sawing. Thus, the sample blank had portions on the ceramic body, the metal layer, and the bonding layer between them. The sample blank was first embedded in a mold containing low-shrinkage epoxy resin (Epo-Fix, Struers), with the sample surface oriented perpendicular to the mold wall. The epoxy resin was then cured at room temperature. After curing, the sample blank's surface was mechanically polished with an automatic polishing machine (Tegrapole, Struers) to achieve a roughness of 1 μm or less.

[0083] In the second step, the polished sample surface is conductively coated with iridium to a thickness of 1–5 nm using a metal sputtering system (Q150T, Quorum Technologies).

[0084] In the third step, the analysis zone of the sample surface is examined by scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX). In SEM-EDX, a focused primary electron beam is guided (screened) point-by-point across the sample surface. The scattered electrons are detected using a detector, and the number of electrons per pixel produces a grayscale microscopic image of the sample surface. Furthermore, the primary electron beam excites the sample to emit characteristic X-ray radiation. The elements and their weight percentages in the sample can be determined by analyzing the energy spectrum using an EDX detector. For the examination, 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) are used. For the scanning electron microscope, the following settings are used: magnification: 1000x, accelerating voltage = 15 kV, working distance = 10 mm, spot size (50-60) (set to reach 25% + / - 5% of the dead time of the EDX detector).

[0085] In the fourth step, the sample surface is detected using EDX software as an electron micrograph (backscattered electron micrograph). A rectangular field of view of at least 125 μm (horizontal) x 90 μm (vertical) is obtained, and an analysis zone is defined using the point analysis function of the EDX software. The analysis zone can be described as follows, with reference to Figure 1. a) The sample surface is oriented so that the cutout of the ceramic body 120 is at the bottom and the cutout of the metal layer 110 is at the top in the electron micrograph 100. In the electron micrograph 100, a transition 5 is visible between the ceramic body (dark) 120 and the bonding or metal layer (light) 110. The rectangular lower boundary 10 of the analysis zone 130 is delineated by a line parallel to the transition 5, which line extends directly through the ceramic body 120 exclusively at this transition 5. b) In this orientation, the sample surface is examined for the presence of metal M2 with a melting point below 700°C and for the presence of active metal M3. A grayscale image of the electron micrograph 100 within the bonding or metal layer 110 is examined, with metal M2 having the brightest pixels and metal M3 having the darkest pixels (excluding the ceramic body). A line in the electron micrograph 100 parallel to the rectangular lower boundary 10 of the analysis zone 130 passes through the farthest point where either metal M2 or metal M3 with a melting point below 700°C is detected, forming the rectangular upper boundary 20 of the analysis zone 130. c) The left and right boundary lines 30 and 40 of the rectangle of the analysis zone 130 run parallel to each other at a distance corresponding to the distance of the boundary lines of the field of view of the sample surface (preferably 125 μm) and are perpendicular to the lower and upper boundary lines 10 and 20.

[0086] In the fifth step, detect the EDX spectrum using the following settings on the EDX detector: live time = 30 s, speed = auto, low energy cutoff = 100 keV, high energy cutoff = auto (per SEM accelerating voltage).

[0087] In the sixth step, the spectrum is analyzed. For this purpose, the elements to be examined are selected, and the elements contained in the ceramic body (the presence of which can optionally be determined in advance by conventional testing methods), iridium, and the elements of the epoxy resin are deselected. The amounts of each of the examined elements are expressed in weight percent, the total amount corresponding to 100%.

[0088] Steps 3 to 6 are repeated 9 times at different points, and then the average value is determined from the values obtained from the 10 individual measurements.

[0089] (ii) the ratio of the content of element M4 in the bonding layer to the content of metal M2 in the bonding layer (characteristic [M(M4) / M(M2)] ICP How to determine: Ratio [M(M4) / M(M2)] in the bonding layer of metal-ceramic substrate ICP is preferably determined as follows:

[0090] The metal-ceramic substrate to be examined is transferred to a plastic beaker made of HDPE (high density polyethylene) and mixed with hydrochloric acid (concentration = 30%) and nitric acid (concentration = 65%) at low heat. Hydrofluoric acid (concentration = 40%) is added to the digestion to dissolve further insoluble components. For metal-ceramic substrates of conventional dimensions, the following amounts of acid have proven advantageous: 30 mL of hydrochloric acid (concentration = 30%), 20 mL of nitric acid (concentration = 65%) and 50 μL of hydrofluoric acid (concentration = 40%).

[0091] The sample solution thus obtained is transferred to a tared polyethylene bottle. The sample solution is then diluted with water according to the expected content of the element being tested. An aliquot of the sample solution is transferred to a 100 mL volumetric flask, and 10 mL of hydrochloric acid (30 wt%), 10 mL of buffered saline (10 g / L sodium chloride), and a calibration standard (e.g., 1 g / L yttrium solution) are prepared. The measurement solution thus obtained is analyzed using ICP-OES (inductively coupled plasma-optical emission spectroscopy) to determine the ratio [M(M4) / M(M2)] relative to the calibration standard. ICP For this purpose, an ICP optical emission spectrometer iCAP 6500 Duo (Thermo Scientific Inc.) was used, and the following plasma settings were configured for the measurement: purge pump speed (rpm): 35; analysis pump speed (rpm): 35; pump tubing type: Tygon Orange / white; HF power: 1150 W; atomizer gas: 0.60 L / min; auxiliary gas: 0.5 L / min.

[0092] The present invention is illustrated by the following exemplary embodiments, which should not be construed as limiting.

[0093] Example Preparation of metal-ceramic substrates (Examples 1-8 and Comparative Examples 1-7): In Examples 1 to 8 and Comparative Examples 1 to 7, metal-ceramic substrates with different bonding layer compositions were produced. This resulted in laminates containing a ceramic body, a metal foil, and a solder material in contact with the ceramic body and the metal foil, which were then heated. The metal-ceramic substrates thus obtained were then tested for their bonding strength and their thermal and electrical conductivities.

[0094] For the production of metal-ceramic substrates 1 to 8 according to the present invention and comparative examples 1 to 7, pastes according to the compositions shown in Table 1 were first prepared.

[0095] [Table 1]

[0096] For this purpose, tin, titanium hydride, and bismuth were successively introduced as powders in the amounts specified into the indicated amount of organic vehicle containing Texanol, and mixed in each case for 20 minutes at 35 Hz in a static mixer until a homogeneous paste was obtained. Then, copper powder was added in small portions. The mixture thus obtained was stirred until a homogeneous paste was obtained.

[0097] The pastes thus produced were used to bond both sides of a ceramic body to copper foil. For this purpose, a ceramic body having dimensions of 177.8 x 139.7 x 0.32 mm (obtained from Toshiba Materials) was used, which had identical front and back surfaces. Each paste was applied to a ceramic body having dimensions of 137 x 175 mm using a 165 mesh screen. 2The area of the paste was screen printed on the backside of such a ceramic body and pre-dried at 125°C for 15 minutes. The paste thickness after pre-drying was 35±5µm. The device thus produced was then rotated, and the paste was uniformly printed on the surface of the ceramic body and pre-dried. Subsequently, copper foil made of oxygen-free, highly electrically conductive copper having a purity of 99.99% and dimensions of 174 x 137 x 0.3 mm was provided on both sides of the ceramic body with paste provided on both sides to obtain a laminate with the following structure: copper foil - pre-dried paste - ceramic - pre-dried paste - copper foil.

[0098] The laminate was then heated in a continuous oven. For this purpose, a silicon carbide plate with graphite foil applied was first placed on the transport chain of the continuous oven. The laminate was placed on the graphite foil, then the laminate was covered with further graphite foil, and the laminate was weighted down with a further silicon carbide plate (weight = 600 g). The structure was then transported on the transport chain through the heating zone of the continuous oven and heated for 2 minutes, starting from 50 ° C to a peak temperature of 935 ° C (measured on the laminate using a type K thermocouple from Temperatur Messelemente Hettstedt GmbH) within 25 minutes. The temperature of the structure was then cooled back to 50 ° C within 25 minutes.

[0099] The metal-ceramic substrate thus obtained was then cooled to room temperature to obtain a metal-ceramic substrate including a ceramic layer bonded to the copper layer on each side via a bonding layer.

[0100] evaluation: The values according to Table 2 were determined for the metal-ceramic substrates of Examples 1-8 and Comparative Examples 1-7:

[0101] [Table 2]

[0102] Furthermore, on the metal-ceramic substrates of Examples 1 to 8 and Comparative Examples 1 to 7, the bond strength was determined by a peel strength test, and the electrical conductivity and thermal conductivity were determined.

[0103] The results are shown in Table 3.

[0104] [Table 3] explanation: +++: Adhesion strength in peel strength test > 100N / cm. ++: Adhesion strength in peel strength test = 75<100N / cm. +: Adhesion strength in peel strength test = 40<75N / cm. -: Peel strength test adhesive strength <40N / cm.

[0105] Exemplary embodiments depict metal-ceramic substrates that meet the following criteria: (c1)M(M2) EDX =10~20% by weight, (c2)15% by weight≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦100% by weight, and (c3) M(Ag) EDX =0~10% by weight

[0106] The bonding layer has a stable bond between the metal layer and the ceramic body while simultaneously having high thermal and electrical conductivity. Because these metal-ceramic substrates do not contain silver, they do not suffer from problems associated with silver migration. In contrast, metal-ceramic substrates that do not satisfy conditions (c1) and (c2) result in unstable bonding between the metal layer and the ceramic body, or the resulting metal-ceramic substrate has comparatively low thermal and electrical conductivity.

[0107] Preparation of Metal-Ceramic Substrates (Examples 9 and 10 and Comparative Example 8): In Examples 9 and 10 and Comparative Example 8, metal-ceramic substrates were produced similarly to Examples 1-8 and Comparative Examples 1-7, but with different bonding layer compositions, and then their bonding strength and their thermal and electrical conductivities were examined.

[0108] A paste having the composition shown in Table 4 was used to manufacture the metal-ceramic substrate.

[0109] Table 4: evaluation: The values according to Table 2 were determined for the metal-ceramic substrates of Examples 9 and 10 and Comparative Example 8. Furthermore, the bond strength on the metal-ceramic substrates of Examples 9 and 10 and Comparative Example 8 was determined by a peel strength test, and the electrical conductivity and thermal conductivity were determined.

[0110] [Table 4] The results are shown in Table 5.

[0111] [Table 5] explanation: +++: Adhesion strength in peel strength test > 100N / cm. ++: Adhesion strength in peel strength test = 75<100N / cm. +: Adhesion strength in peel strength test = 40<75N / cm. -: Peel strength test adhesive strength <40N / cm.

[0112] Exemplary embodiments 9 and 10 identify metal-ceramic substrates that meet the following criteria: (c1)M(M2) EDX =10~20% by weight, (c2)15% by weight≦[M(M4) / M(M2)] ICP * 1000wt%+M(M2) EDX ≦100% by weight, and (c3) M(Ag) EDX =0~10% by weight

[0113] The bonding layer has a stable bond between the metal layer and the ceramic body while simultaneously having high thermal and electrical conductivity. Because these metal-ceramic substrates do not contain silver, they do not suffer from problems associated with silver migration. In contrast, metal-ceramic substrates that do not satisfy conditions (c1) and (c2) result in unstable bonding between the metal layer and the ceramic body, or the resulting metal-ceramic substrate has comparatively low thermal and electrical conductivity. [Brief explanation of the drawings]

[0114] [Figure 1] FIG. 1 is an electron microscope photograph of the bond layer of a metal-ceramic substrate.

Claims

1. (a) a ceramic body; (b) a metal layer; (c) a bonding layer located between the ceramic body and the metal layer, (i) a metal M1 having a melting point of at least 700°C, said metal M1 being copper; (ii) a metal M2 having a melting point of less than 700°C, said metal M2 being tin; (iii) a metal M3 selected from the group of active metals, wherein the metal M3 is selected from the group consisting of titanium and zirconium, and the content of the metal M3 in the bonding layer determined using EDX (M(M3) EDX ) is in the range of 0.5 to 15 wt. %; and (iv) a metal M4 selected from the group consisting of bismuth and germanium a bonding layer including: A metal-ceramic substrate comprising: The bonding layer has the following properties: (c1)M(M2) ＥＤＸ =10~20 wt%, (c2) 15 wt% ≦ [M (M4) / M (M2)] ＩＣＰ ＊ 1000 wt% + M (M2) ＥＤＸ ≦100% by weight, and (c3)M(Ag) ＥＤＸ <10% by weight characterized in that it has During the ceremony, M (M2) ＥＤＸ is the content [wt %] of the metal M2 in the bonding layer determined using EDX, [M(M4) / M(M2)] ＩＣＰ is the ratio of the content of metal M4 in the bonding layer to the content of metal M2 in the bonding layer, determined using ICP; M(Ag) ＥＤＸ is the silver content [wt %] in the bonding layer, determined using EDX; Metal-ceramic substrate.

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 said metal M4 is bismuth.

4. The bonding layer has the following characteristics: (c1')M(M2) ＥＤＸ =10~15wt% 3. The metal-ceramic substrate according to claim 1, wherein the metal-ceramic substrate has a structure as follows:

5. The bonding layer has the following characteristics: (c2') 15 wt% ≦ [M (M4) / M (M2)] ＩＣＰ ＊ 1000 wt% + M (M2) ＥＤＸ ≦70% by weight 3. The metal-ceramic substrate according to claim 1, wherein the metal-ceramic substrate has a structure as follows:

6. The bonding layer has the following characteristics: (c3')M(Ag) ＥＤＸ <1% by weight 3. The metal-ceramic substrate according to claim 1, wherein the metal-ceramic substrate has a structure as follows:

7. A module comprising the metal-ceramic substrate of claim 1 or 2.

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