Active metal solder substrate materials and their manufacturing methods

Abstract

This application discloses an active metal bonding substrate material and its manufacturing method. The substrate material comprises a ceramic substrate layer, a first bonding layer, a second bonding layer, and a conductive metal layer stacked sequentially. The first bonding layer comprises a first metal composite material containing silver (Ag), copper (Cu), and a first active metal component. Based on a total weight of 100 parts by weight of the first metal composite material, the silver content is not less than 50 parts by weight. The second bonding layer comprises a second metal composite material containing a low-melting-point metal component, copper, and a second active metal component, but does not contain silver. The melting point of the low-melting-point metal component is between 130°C and 350°C. Based on a total weight of 100 parts by weight of the second metal composite material, the low-melting-point metal component content is between 10 and 40 parts by weight. This effectively reduces the amount of silver used and lowers the bonding temperature to below 900°C, thereby reducing the impact of high temperatures on metal properties and simultaneously reducing material and process costs.

Description

Technical Field

[0001] This application relates to a substrate material, and more particularly to an active metal solder (AMB) substrate material and a method for manufacturing the same. Background Technology

[0002] Driven by energy conservation and carbon reduction policies in various countries, the global electric vehicle market is booming. With major automakers launching 800-volt high-voltage models in recent years, the demand for silicon carbide (SiC) ceramic substrate materials has grown rapidly.

[0003] However, the requirements for voltage, frequency and operating temperature of power components based on silicon carbide (SiC) ceramic substrates are constantly increasing, which means that the ceramic substrate materials also need to have better heat dissipation capabilities and reliability.

[0004] Previously widely used direct-bonding-copper (DBC) ceramic substrates were fabricated using a eutectic bonding method, with no bonding material between the copper layer and the ceramic substrate. However, during high-temperature operation, the difference in thermal expansion coefficients between the copper layer and the ceramic substrate (such as Al2O3 or AlN) often generates significant thermal stress, leading to the copper layer peeling off from the surface of the ceramic substrate. Therefore, traditional direct-bonding-copper ceramic substrates are no longer sufficient to meet the packaging requirements of high temperature, high power, high heat dissipation, and high reliability.

[0005] Currently, the mainstream substrate materials are gradually shifting from direct copper-clad ceramic substrates to active metal brazing (AMB) substrate materials.

[0006] Active metal soldering substrates utilize the property that active metal elements (such as Ti, Zr, Ta, Nb, V, Hf, etc.) can wet the surface of ceramic substrates, allowing ultra-thick copper foil to be hard-soldered onto the ceramic substrate at high temperatures. The solder layer formed between the copper layer and the ceramic substrate through the active metal soldering process exhibits higher bonding strength.

[0007] Among common active metal solder paste materials, silver-copper-titanium (Ag-Cu-Ti) is a frequently used metal composite material. In the aforementioned silver-copper-titanium metal composite material, the silver content typically exceeds 50% (weight percentage concentration), and can even reach as high as 70%.

[0008] Generally, the soldering temperature for active metal solder paste materials using silver, copper, and titanium typically needs to reach above 900℃ (e.g., 915℃). The solder layer formed by this active metal soldering contains a large amount of metallic silver (a precious metal), resulting in high material and manufacturing costs for active metal soldered ceramic substrates. Furthermore, the electromigration problem caused by residual metallic silver from the etching process remains a challenge that needs to be addressed. Summary of the Invention

[0009] The technical problem to be solved by this application is to provide an active metal brazing (AMB) substrate material and its manufacturing method to address the shortcomings of the prior art. This material can reduce the amount of metallic silver used and reduce the brazing temperature to below 900°C, thereby reducing the impact of high-temperature processes on metal properties and simultaneously reducing material costs and process costs.

[0010] This application discloses an active metal bonding substrate material, comprising: a ceramic substrate layer; an active metal layer, including: a first bonding layer disposed on one side surface of the ceramic substrate layer; wherein the first bonding layer comprises a first metal composite material comprising: metallic silver (Ag), metallic copper (Cu), and a first active metal component; based on a total weight of 100 parts by weight of the first metal composite material, the content of metallic silver is not less than 50 parts by weight; and a second bonding layer disposed on the side surface of the first bonding layer away from the ceramic substrate layer; wherein the second bonding layer comprises a second metal composite material comprising: low melting point gold. The composition comprises a metal component, metallic copper (Cu), and a second active metal component, but does not contain metallic silver (Ag); wherein the melting point of the low-melting-point metal component is between 130°C and 350°C; and based on a total weight of 100 parts by weight of the second metal composite material, the content of the low-melting-point metal component is between 10 parts by weight and 40 parts by weight; wherein the sum of the thicknesses of the first solder layer and the second solder layer is at least 12 micrometers, and the thickness of the first solder layer is at least 5 micrometers, while the thickness of the second solder layer is at least 10 micrometers; and a conductive metal layer disposed on the surface of the second solder layer away from the first solder layer.

[0011] Optionally, the low-melting-point metal component has a content between 5 g·cm⁻¹. -3 Up to 12g·cm -3 The liquid density at its melting point and the resistivity not exceeding 1500 nΩ·m between 0°C and 25°C.

[0012] Optionally, the low-melting-point metal component is at least one of tin (Sn), bismuth (Bi), indium (In), lead (Pb), and cadmium (Cd).

[0013] Optionally, based on the total weight of all metal components in the active metal layer being 100wt%, the content of the low melting point metal component being between 5wt% and 35wt%, the content of the metallic silver being no more than 45wt%, the total content of the first active metal component and the second active metal component being between 1wt% and 5wt%, and the metallic copper being the balance metal component.

[0014] Optionally, the content of metallic copper in the second solder layer is higher than the content of the low-melting-point metal component in the second solder layer; and the content of metallic copper in the second solder layer is higher than the content of metallic copper in the first solder layer.

[0015] Optionally, in the active metal layer, the thickness ratio between the thickness of the first solder layer and the thickness of the second solder layer is between 15% and 50% and 50% and 85%, respectively.

[0016] Optionally, the first active metal component and the second active metal component are selected from at least one of the material group consisting of titanium, zirconium, tantalum, niobium, vanadium, hafnium and hydrides of the above metals; wherein the ceramic substrate layer is at least one of silicon nitride ceramic substrate, silicon carbide ceramic substrate, aluminum nitride ceramic substrate and alumina ceramic substrate; wherein the conductive metal layer is at least one of copper foil, aluminum foil and copper-aluminum alloy foil.

[0017] This application also discloses a method for manufacturing an active metal solder substrate material, comprising: performing a first solder layer preparation operation, including: applying a first active solder paste to one side surface of a ceramic substrate layer and drying it to form a first solder layer; wherein the first active solder paste comprises a first active solder powder, which is composed of metallic silver powder, metallic copper powder and a first active metal powder; wherein, based on 100 parts by weight of the first active solder powder, the content of the metallic silver powder is not less than 50 parts by weight; performing a second solder layer preparation operation, including: applying a second active solder paste to one side surface of the first solder layer away from the ceramic substrate layer and drying it to form a second solder layer; wherein the second active solder paste comprises a first active solder powder, which is composed of metallic silver powder, metallic copper powder and a first active metal powder; wherein the first ... The second active solder powder comprises a low-melting-point metal powder, a copper powder, and a second active metal powder; wherein the low-melting-point metal powder has a melting point between 130°C and 350°C; based on a total weight of 100 parts by weight of the second active solder powder, the content of the low-melting-point metal powder is between 10 parts by weight and 40 parts by weight; wherein the second active solder powder does not contain silver powder; and performing a conductive metal layer preparation operation, comprising: disposing a conductive metal layer on the surface of the second solder layer away from the first solder layer, and hard soldering the conductive metal layer onto the ceramic substrate layer through an active metal layer composed of the first solder layer and the second solder layer under a vacuum high-temperature sintering process.

[0018] Wherein, the total thickness of the first hard solder layer and the second hard solder layer is not less than 12 micrometers, the thickness of the first hard solder layer is not less than 5 micrometers, and the thickness of the second hard solder layer is not less than 10 micrometers.

[0019] Optionally, the weight ratio of the first active solder powder to the first active metal powder is between 50-75: 20-48: 2-5; the weight ratio of the second active solder powder to the second active metal powder is between 10-40: 55-90: 1-5.

[0020] Optionally, the vacuum high-temperature sintering process includes: a first-stage heat treatment process with a temperature not exceeding 500°C and a second-stage heat treatment process with a temperature between 450°C and 900°C.

[0021] In summary, the beneficial effects of this application are that the active metal hard solder substrate material and its manufacturing method provided by this application can effectively reduce the amount of metallic silver used and reduce the hard soldering temperature to below 900°C through the design of the "first hard solder layer and the second hard solder layer", thereby reducing the impact of high temperature on metal properties and reducing material costs and process costs at the same time.

[0022] More specifically, in this application, a second solder layer is disposed between the first solder layer and the conductive metal layer. The second solder layer contains a low-melting-point metal component but does not contain metallic silver (Ag). The second solder layer, with a certain thickness, reduces the silver content in the active metal layer, effectively lowering the material and manufacturing costs of the active metal solder ceramic substrate, and effectively mitigating the electromigration problem caused by silver residue. Ultimately, the active metal solder substrate material provided in this application embodiment can be further used to etch circuit patterns onto a ceramic substrate using an exposure and development method, and can be applied to high-power energy conversion modules, electric vehicles, and charging systems, etc.

[0023] To further understand the features and technical content of this application, please refer to the following detailed description and drawings of this application. However, these descriptions and drawings are only used to illustrate this application and are not intended to limit the scope of protection of this application in any way. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the active metal hard solder substrate material in an embodiment of this application.

[0025] Figure 2 This is a schematic diagram showing that both sides of a ceramic substrate have active metal layers.

[0026] Figures 3A to 3D This is a schematic diagram of the substrate material manufacturing process according to an embodiment of this application. Detailed Implementation

[0027] The following specific embodiments illustrate the implementation methods disclosed in this application. Those skilled in the art can understand the advantages and effects of this application from the content disclosed in this specification. This application can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this application. Furthermore, the accompanying drawings of this application are for simple illustration only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of this application in detail, but the disclosed content is not intended to limit the scope of protection of this application.

[0028] It should be understood that although terms such as "first," "second," and "third" may be used in this document to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another.

[0029] Additionally, the term "or" as used in this document should be interpreted as including, depending on the context, any combination of one or more of the related listed items.

[0030] Active metal solder substrate material

[0031] Please see Figure 1 As shown in the figure, this application provides an active metal bonding substrate material 100, which includes: a ceramic substrate layer 1, an active metal layer 2, and a conductive metal layer 3. The active metal layer 2 is disposed between the ceramic substrate layer 1 and the conductive metal layer 3 to connect the ceramic substrate layer 1 and the conductive metal layer 3 together.

[0032] More specifically, the active metal layer 2 includes a first solder layer 21 and a second solder layer 22.

[0033] Furthermore, the first solder layer 21 is disposed on one side surface of the ceramic substrate layer 1, the second solder layer 22 is disposed on the side surface of the first solder layer 21 away from the ceramic substrate layer 1, and the conductive metal layer 3 is disposed on the side surface of the second solder layer 22 away from the first solder layer 21.

[0034] It is worth mentioning that although this embodiment sequentially deposits the first solder layer 21, the second solder layer 22, and the conductive metal layer 3 on one side surface of the ceramic substrate layer 1, this application is not limited to this. For example, such as Figure 2 As shown, in another embodiment of this application, another first solder layer 21', another second solder layer 22', and another conductive metal layer 3' may be sequentially disposed on the other side surface of the ceramic substrate layer 1 to form a symmetrical substrate structure with active metal layers on both sides.

[0035] Ceramic substrate layer

[0036] Furthermore, the ceramic substrate layer 1 can be, for example, at least one of a silicon nitride (SiN) ceramic substrate, a silicon carbide (SiC) ceramic substrate, an aluminum nitride (AlN) ceramic substrate, and an alumina (Al2O3) ceramic substrate. In this embodiment, the ceramic substrate layer 1 is preferably a silicon nitride (SiN) ceramic substrate. Additionally, the thickness T1 of the ceramic substrate layer 1 can be, for example, between 100 micrometers and 1000 micrometers, but this application is not limited to this.

[0037] First hard solder layer

[0038] Please continue reading Figure 1 As shown, the first solder layer 21 comprises a first metal composite material. The first metal composite material comprises: metallic silver (Ag), metallic copper (Cu), and a first active metal component.

[0039] It is worth mentioning that the composition of the first solder layer 21 may further include a small amount of low-melting-point metal components, which may be melted first during the vacuum sintering process of preparing the active metal solder substrate material and diffused from the second solder layer 22 along the defects of the copper into the first solder layer 21.

[0040] Furthermore, in some embodiments of this application, the first active metal component may be selected, for example, from at least one of the group of materials consisting of titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), vanadium (V), hafnium (Hf), and hydrides of the above metals.

[0041] Furthermore, the metal hydride may be, for example, at least one of titanium hydride (TiH2), zirconium hydride (ZrH2), tantalum hydride (TaH2), niobium hydride (NbH), vanadium hydride (VH2), and hafnium hydride (H2Hf2).

[0042] In some embodiments of this application, the first active metal component is preferably at least one of titanium (Ti) and titanium hydride (TiH2). Accordingly, the first solder layer 21 may also be referred to as an Ag-Cu-Tipaste solder layer.

[0043] In terms of content range, the first metal composite material is the main component of the first solder layer 21. For example, the weight percentage concentration of the first metal composite material in the first solder layer 21 is at least 80 wt%, and preferably at least 90 wt%.

[0044] Furthermore, in the first solder layer 21, based on a total weight of 100 parts by weight of the first metal composite material, the content of metallic silver (Ag) is at least 50 parts by weight, and preferably between 50 parts by weight and 75 parts by weight. In terms of thickness, the thickness T21 of the first solder layer 21 is at least 5 micrometers, and preferably between 5 micrometers and 24 micrometers.

[0045] According to the above configuration, since the first solder layer 21 in contact with the ceramic substrate layer 1 contains a certain amount of metallic silver (Ag) and has a thickness within a certain range, the bonding force between the ceramic substrate layer 1 and the conductive metal layer 3 can be improved. If the metallic silver (Ag) content in the first solder layer 21 is too low or the thickness is too thin, the first solder layer 21 will not be able to allow the active metal solder substrate material 100 to exert its due physical properties. If the metallic silver (Ag) content in the first solder layer 21 is too high or the thickness is too thick, it will lead to excessively high material and manufacturing costs for the active metal solder substrate material 100.

[0046] It is worth mentioning that the first active metal component (e.g., Ti) in the first solder layer 21 can wet the surface of the ceramic substrate layer 1 during vacuum sintering and react with ceramic materials (e.g., SiN) to form compounds such as titanium nitride (TiN), titanium silicide (TiSi), or titanium disilicide (TiSi2), thereby improving the bonding force between the active metal layer 2 and the ceramic substrate layer 1.

[0047] On the other hand, since the first solder layer 21 contains an active metal, the electrical impedance of the active metal solder substrate material 100 can be reduced.

[0048] Furthermore, the metallic silver (Ag) and metallic copper (Cu) in the first solder layer 21 can react to form a silver-copper alloy (Ag-Cu alloy).

[0049] Furthermore, the first metal composite material of the first solder layer 21 can be formed, for example, by mixing and vacuum sintering silver powder (Agmetal powder), copper powder (Cumetal powder), active metal powder (such as Ti metal powder), and / or silver-copper alloy (Ag-Cu alloy).

[0050] Second hard solder layer

[0051] The second solder layer 22 comprises a second metal composite material, which includes: a low melting point metal component, copper (Cu) and a second active metal component, and the second metal composite material preferably consists only of the low melting point metal component, copper and the second active metal component.

[0052] It is worth mentioning that, in a preferred embodiment of this application, the second metal composite material of the second solder layer 22 does not contain any metallic silver (Ag).

[0053] Furthermore, as described above, the low-melting-point metal component of the second solder layer may, for example, be melted during the vacuum sintering process of preparing the active metal solder substrate material, and then diffuse into the first solder layer 21 at least partially along the defects of the copper (Cu) metal, but this application is not limited thereto.

[0054] The low-melting-point metal component may, for example, have a melting point (Tm) between 130°C and 350°C, and a melting point between 5 g·cm³. -3 Up to 12g·cm -3 The liquid density at a melting point between [the two values].

[0055] In some embodiments of this application, the low-melting-point metal component may be, for example, at least one of tin (Sn), bismuth (Bi), indium (In), lead (Pb), and cadmium (Cd).

[0056] For example, metallic tin (Sn) has a melting point of approximately 232°C and a liquid density of approximately 7 g·cm³ at that melting point. -3 The melting point of metallic bismuth (Bi) is approximately 271.5 °C, and its liquid density at the melting point is approximately 10 g·cm³. -3 The melting point of metallic indium (In) is approximately 156.5°C, and its liquid density at the melting point is approximately 7 g·cm³. -3 Metallic lead (Pb) has a melting point of approximately 327.5°C, and its liquid density at that melting point is approximately 8 g·cm³. -3 The melting point of metallic cadmium (Cd) is approximately 321°C, and its liquid density at the melting point is approximately 8 g·cm³. -3 .

[0057] Furthermore, the aforementioned low-melting-point metal components all possess an electrical resistivity of no more than 1500 nΩ·m between 0°C and 25°C, making them suitable for use in conductive welding materials.

[0058] Furthermore, similar to the first active metal component, the second active metal component may be, for example, selected from at least one of the group of materials composed of titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), vanadium (V), hafnium (Hf), and hydrides of the above metals. The metal hydride may be, for example, at least one of titanium hydride (TiH2), zirconium hydride (ZrH2), tantalum hydride (TaH2), niobium hydride (NbH), vanadium hydride (VH2), and hafnium hydride (H2Hf2).

[0059] In one specific embodiment of this application, the low-melting-point metal component is metallic tin (Sn), and the second active metal component is titanium (Ti). Accordingly, the second solder layer 22 can also be referred to as a tin-copper-titanium solder layer (Sn-Cu-Tipaste).

[0060] In terms of content range, the second metal composite material is the main component of the second solder layer 22. For example, the weight percentage concentration of the second metal composite material in the second solder layer 22 is at least 80 wt%, and preferably at least 90 wt%.

[0061] Furthermore, in the second solder layer 22, based on a total weight of 100 parts by weight of the second metal composite material, the content of the low-melting-point metal component (such as Sn) is between 10 parts by weight and 40 parts by weight, and preferably between 15 parts by weight and 35 parts by weight. The content of the metallic copper (Cu) is between 55 parts by weight and 90 parts by weight, and preferably between 60 parts by weight and 85 parts by weight. The content of the second active metal component (such as Ti) is between 1 part by weight and 5 parts by weight, and preferably between 2 parts by weight and 4 parts by weight.

[0062] In some embodiments of this application, the content of metallic copper in the second solder layer 22 (e.g., 55 to 90 parts by weight) is higher than the content of the low-melting-point metal component in the second solder layer 22 (e.g., 10 to 40 parts by weight). Furthermore, the content of metallic copper in the second solder layer 22 (e.g., 55 to 90 parts by weight) is higher than the content of metallic copper in the first solder layer 21 (e.g., 10 to 40 parts by weight).

[0063] In terms of thickness range, the thickness T22 of the second solder layer 22 is at least not less than 10 micrometers, and preferably between 10 micrometers and 24 micrometers.

[0064] It is worth mentioning that the low-melting-point metal component in the second solder layer 22 can react with metallic copper (Cu) during vacuum sintering. For example, let's consider a low-melting-point metal component made of metallic tin (such as Sn). When the heating temperature exceeds the melting point of metallic tin (e.g., above 240°C), the metallic tin will melt first. With an excess of metallic copper, the metallic tin and metallic copper will first form a Cu3Sn alloy, which will exist in the second solder layer 22 and at the interface between the second solder layer 22 and the conductive metal layer 3 (such as copper foil). Furthermore, the Cu3Sn alloy will react with more metallic tin to form a Cu6Sn5 alloy. This allows the second solder layer 22 to bond more tightly to the conductive metal layer 3.

[0065] Furthermore, the second metal composite material of the second solder layer 22 can be formed, for example, by mixing and vacuum sintering a low-melting-point metal powder, copper powder (Cu metalpowder), and an active metal powder (such as Ti metalpowder). Additionally, the second active metal component (such as Ti) in the second solder layer 22 can diffuse through the first solder layer 21 to the ceramic substrate layer 1 during vacuum sintering and react with the ceramic material (such as SiN) to form compounds such as titanium nitride (TiN), titanium silicide (TiSi), or titanium disilicide (TiSi2).

[0066] active metal layer thickness ratio and metal content

[0067] From another perspective, the total thickness of the active metal layer 2 (i.e., the sum of the thicknesses T21 of the first solder layer 21 and T22 of the second solder layer 22) is at least 12 micrometers, preferably at least 15 micrometers, and particularly preferably between 15 micrometers and 32 micrometers. The thickness ratio between the thicknesses T21 of the first solder layer 21 and T22 of the second solder layer 22 is preferably 15%–50%: 50%–85% (and the sum is 100%), and particularly preferably 20%–45%: 55%–80%.

[0068] Accordingly, based on the total weight of all metal components in the active metal layer 2 being 100 wt%, the content of the low-melting-point metal component is between 5 wt% and 35 wt%, preferably between 10 wt% and 35 wt%. The content of the metallic silver (Ag) is not greater than 45 wt%, preferably between 15 wt% and 45 wt%.

[0069] The total content of the first and second active metal components (e.g., titanium) is between 1 wt% and 5 wt%, preferably between 2 wt% and 4 wt%. The copper (Cu) is the balance metal component. The addition of silver (Ag) can act as a stabilizer to improve device performance.

[0070] According to the above configuration, the second solder layer 22 is disposed between the first solder layer 21 and the conductive metal layer 3. The second solder layer 22 contains a low-melting-point metal and does not contain metallic silver (Ag). The second solder layer 22, occupying a certain thickness, can effectively reduce the content of metallic silver in the active metal layer 2, thereby effectively reducing the material cost and manufacturing cost of the active metal solder ceramic substrate, and can effectively improve the electromigration problem caused by metallic silver residue. Furthermore, the second solder layer 22 can firmly connect the first solder layer 21 and the conductive metal layer 3 together.

[0071] Furthermore, in some embodiments of this application, the active metal layer 2, due to the increased content of low-melting-point metals, can be brazed at a brazing temperature not exceeding 900°C. In one specific embodiment, the brazing temperature at which the active metal layer 2 is heated is between 450°C and 900°C, but is not limited thereto. Accordingly, since the active metal layer 2 has a lower brazing temperature than prior art, the impact of high temperatures on metal properties can be effectively mitigated.

[0072] conductive metal layer

[0073] Please continue reading Figure 1As shown, the conductive metal layer 3 is disposed on the surface of the second solder layer 22 away from the first solder layer 21. The conductive metal layer 3 can be, for example, a metal copper foil, a metal aluminum foil, or a copper-aluminum alloy foil. In this embodiment, the conductive metal layer 3 is preferably a metal copper foil.

[0074] Additionally, the thickness T3 of the conductive metal layer 3 may be, for example, between 50 micrometers and 800 micrometers, but this application is not limited to this.

[0075] It is worth mentioning that the conductive metal layer 3 (e.g., oxygen-free copper) can be hard-bonded to the ceramic substrate layer 1 via the active metal layer 2, for example, through vacuum high-temperature sintering. For instance, the vacuum high-temperature sintering process may include a first-stage heat treatment process and a second-stage heat treatment process. The temperature conditions of the first-stage heat treatment process are no greater than 500°C, and the temperature conditions of the second-stage heat treatment process are between 450 and 900°C (i.e., the hard-bonding temperature range).

[0076] According to the above configuration, the active metal hard soldering substrate material provided in this application embodiment can effectively reduce the amount of metallic silver and reduce the hard soldering temperature to below 900°C, thereby reducing the impact of high temperature on metal properties and simultaneously reducing material costs and process costs.

[0077] It is worth noting that the "soldering temperature" of the active metal layer 2 referred to in this paper refers to the temperature at which the metal components can melt and have sufficient fluidity to wet the surface of the workpiece (such as a ceramic substrate). Generally, a soldering temperature above 450°C is called the soldering temperature. The soldering temperature can be determined, for example, by using a ternary metallographic diagram of the three metal components to determine the appropriate weight percentage concentration of each metal material. Alternatively, a suitable soldering temperature range can be found by using a ternary metallographic diagram of the three metal components and the known weight percentage concentrations of these metal materials. For example, a suitable soldering temperature is a temperature higher than the liquidus temperature of the ternary metal components of the solder filler, which allows the solder filler to have sufficient fluidity, but this application is not limited to this.

[0078] Method for manufacturing active metal hard solder substrate materials

[0079] The above describes the structural and material characteristics of the active metal hard solder substrate material. The following will describe the manufacturing method of the active metal hard solder substrate material of this application.

[0080] like Figures 3A to 3DAs shown, this application embodiment also provides a method for manufacturing an active metal hard solder substrate material, which includes steps S110, S120, S130, and S140. It should be noted that the order of the steps and the actual operation method described in this embodiment can be adjusted according to needs and are not limited to those described in this embodiment.

[0081] like Figure 3A As shown, step S110 involves providing a ceramic substrate layer 1. The ceramic substrate layer 1 may be, for example, at least one of a silicon nitride (SiN) ceramic substrate, a silicon carbide (SiC) ceramic substrate, an aluminum nitride (AlN) ceramic substrate, and an alumina (Al2O3) ceramic substrate.

[0082] Preferably, the ceramic substrate layer 1 is a silicon nitride (SiN) ceramic substrate.

[0083] like Figure 3B As shown, step S120 is to perform a first solder layer preparation operation, which includes: applying a first active solder paste to one side surface of the ceramic substrate layer 1, and drying the first active solder paste at high temperature to remove most of the organic solvent in the first active solder paste, thereby forming a first solder layer 21.

[0084] The first active solder paste is prepared by mixing and formulating a first active solder powder with organic components (such as paste-forming agents, organic solvents and thixotropic agents) and adjusting it to a suitable viscosity (such as 50 to 300 mPa·s) so that the solder paste can be easily applied to the ceramic substrate layer 1.

[0085] For example, the first active solder paste can be applied to the surface of a ceramic substrate by screen printing and dried at a temperature of 90°C to 110°C for 5 to 15 minutes to allow most of the organic solvents in the first active solder paste to evaporate, thereby forming the first hard solder layer 21.

[0086] In some embodiments of this application, the weight ratio between the first active solder powder and the organic component may be, for example, between 70% and 95% and 5% and 30%, and preferably between 75% and 90% and 10% and 25%.

[0087] The first active solder powder (forming the first metal composite material) is a powder formed by mixing silver powder (Ag metalpowder), copper powder (Cu metal powder) and a first active metal powder (such as titanium powder).

[0088] The weight ratio of silver (Ag): copper (Cu): first active metal powder (Ti, TiH2) can be, for example, between 50-75:20-49:1-5, and in a specific embodiment it is 68:28:4, but this application is not limited thereto.

[0089] In the organic components, the weight ratio of ointment-forming agent: organic solvent: thixotropic agent can be, for example, between 20% to 30%: 50% to 70%: 1% to 5%.

[0090] The ointment-forming agent may be selected from at least one of the materials group consisting of silicone oil, white oil, polyvinyl alcohol, acrylic resin, nitrocellulose, ethyl cellulose, dimethyl phthalate, and carboxymethyl cellulose. Preferably, the ointment-forming agent is ethyl cellulose.

[0091] The organic solvent may be selected from at least one of the group consisting of ethylene glycol butyl ether acetate, diethylene glycol, triethanolamine, butyl cellosolve, tert-butanol, N,N-dimethylformamide, terpineol, and nonylphenol polyethylene glycol ether. Preferably, the organic solvent is terpineol or ethylene glycol butyl ether acetate.

[0092] The thixotropic agent may be selected from at least one of the materials group consisting of polyamide wax, hydrogenated castor oil, and polyurea. Preferably, the thixotropic agent is polyamide wax.

[0093] However, this application is not limited to the above-described embodiments. Any active solder powder that can be mixed with organic components to form an active solder paste with a viscosity suitable for coating on a ceramic substrate to facilitate the formation of a hard solder layer is in line with the spirit of this application and falls within the scope of protection of this application.

[0094] like Figure 3C As shown, step S130 is to perform a second solder layer preparation operation, which includes: applying a second active solder paste to the surface of the first solder layer 21 away from the ceramic substrate layer 1, and drying the second active solder paste at high temperature to remove most of the organic solvent in the second active solder paste, thereby forming a second solder layer 22.

[0095] The second active solder paste is prepared by mixing the second active solder powder and organic components to a suitable viscosity (e.g., 50-300 mPa·s) to facilitate application onto the first hard solder layer 21.

[0096] For example, the second active solder paste can be applied to the first solder layer 21 by screen printing and dried at a temperature of 90°C to 110°C for 5 to 15 minutes to allow most of the organic solvents in the second active solder paste to evaporate, thereby forming the second solder layer 22.

[0097] In some embodiments of this application, the weight ratio between the second active solder powder and the organic component may be, for example, between 70% and 95% and 5% and 30%, and preferably between 75% and 90% and 10% and 25%.

[0098] The second active solder powder (which can form the aforementioned second metal composite material) is a powder formed by mixing low melting point metal powder, copper powder, and a second active metal powder (such as titanium powder). The weight ratio of the low melting point metal (such as Sn): copper (Cu): second active metal powder (such as Ti) can be, for example, between 10–40:55–90:1–5. For example, in one specific embodiment, the weight ratio of Sn:Cu:Ti can be, for example, [23:75:2], but this application is not limited to this.

[0099] It is worth mentioning that the second active solder powder does not contain metallic silver powder.

[0100] The proportions and types of organic components in the second active solder paste are similar to those in the first active solder paste, and will not be repeated here.

[0101] like Figure 3D As shown, step S140 involves preparing a conductive metal layer, which includes: disposing a conductive metal layer 3 on the surface of the second solder layer 22 away from the first solder layer 21; and soldering the conductive metal layer 3 onto the ceramic substrate layer 1 through an active metal layer 2 formed by the first solder layer 21 and the second solder layer 22 under a vacuum high-temperature sintering process. The conductive metal layer 3 can be, for example, a copper foil, an aluminum foil, or a copper-aluminum alloy foil.

[0102] The vacuum high-temperature sintering process may, for example, include a first-stage heat treatment process and a second-stage heat treatment process. The temperature conditions of the first-stage heat treatment process are no greater than 500°C, and the temperature conditions of the second-stage heat treatment process are between 450 and 900°C (i.e., the hard soldering temperature range), which are greater than the temperature conditions of the first-stage heat treatment process.

[0103] More specifically, the temperature conditions of the first stage heat treatment process are between 300°C and 500°C, and the treatment time is between 30 minutes and 60 minutes. The temperature conditions of the second stage heat treatment process are between 450°C and 900°C (within a suitable hard soldering temperature range), and the treatment time is between 60 minutes and 240 minutes. Furthermore, the heating rate of the above heat treatment process can be, for example, 5 to 30°C / min. The cooling rate after vacuum high-temperature sintering can be, for example, 2 to 30°C / min.

[0104] It is worth mentioning that during the vacuum sintering process, the organic components in the first and second solder layers will at least partially vaporize. The first and second active metal components (e.g., Ti) can wet the surface of the ceramic substrate layer 1 and react with the ceramic material (e.g., SiN) to form compounds such as titanium nitride (TiN), titanium silicide (TiSi), or titanium disilicide (TiSi2), thereby improving the bonding force between the active metal layer 2 and the ceramic substrate layer 1. Furthermore, the second solder layer 22 can undergo a micron-level eutectic reaction (e.g., eutectic reaction between tin and copper) with the metal components (e.g., copper) of the conductive metal layer 3 at the interface, forming a strong eutectic structure, so that the active metal layer 2 can be tightly bonded to the conductive metal layer 3.

[0105] It is worth mentioning that the total thickness of the active metal layer 2 (i.e., the sum of the thickness T21 of the first solder layer 21 and the thickness T22 of the second solder layer 22) is at least 12 micrometers, preferably at least 15 micrometers, and particularly preferably between 15 micrometers and 32 micrometers. Furthermore, the thickness ratio of the first solder layer 21 thickness T21 to the second solder layer 22 thickness T22 is between 15% and 50% and 50% and 85% (and the sum is 100%).

[0106] Furthermore, based on the total weight of all metal components in the active metal layer 2 being 100 wt%, the content of the low-melting-point metal component is between 5 wt% and 35 wt%, preferably between 10 wt% and 35 wt%. The content of the metallic silver (Ag) is not greater than 45 wt%, and preferably between 15 wt% and 45 wt%. Moreover, the total content of the first and second active metal components (e.g., titanium) is between 1 wt% and 5 wt%, preferably between 2 wt% and 4 wt%. The metallic copper (Cu) is the balance metal component.

[0107] Accordingly, the technical solution provided in this application embodiment can reduce the amount of metallic silver used and reduce the hard soldering temperature to below 900°C, thereby reducing the impact of high temperature on metal properties and effectively reducing material costs and process costs.

[0108] Experimental data and test results

[0109] Hereinafter, the contents of this application will be described in detail with reference to Examples 1 and 2 and Comparative Examples 1 and 2. The examples are experimental groups that demonstrate the technical effects of this application, while the comparative examples are groups with less favorable conditions. However, the following examples are only provided to help understand this application, and this application is not limited thereto.

[0110] Example 1: An active metal solder substrate material comprising a first solder layer and a second solder layer was prepared according to the conditions in Table 1. The preparation method included: applying a first active solder paste containing 68 parts by weight of silver powder (Ag), 28 parts by weight of copper powder (Cu), and 4 parts by weight of titanium powder (Ti) onto the surface of a ceramic substrate, and drying it at high temperature to form the first solder layer. Then, applying a second active solder paste containing 75 parts by weight of copper powder (Cu), 23 parts by weight of low-melting-point metal powder (tin Sn powder in this example), and 2 parts by weight of titanium powder (Ti) onto the first solder layer, and drying it at high temperature to form the second solder layer. Then, a copper foil was further disposed on the second solder layer to form a laminated material. Next, the laminated material was subjected to vacuum high-temperature sintering to finally form the active metal solder substrate material. In Example 1, the temperature conditions for the first stage of hot soldering in the vacuum high-temperature sintering were 650°C, and the processing time was 30 minutes. The second-stage hot soldering temperature is 900℃, and the processing time is 60 minutes. That is, the soldering temperature is 650-900℃. Furthermore, the ceramic substrate is a silicon nitride (SiN) ceramic substrate with a thickness of 320 micrometers. The thickness of the first solder layer is 6 micrometers, the thickness of the second solder layer is 12 micrometers, and the thickness of the copper foil is 500 micrometers.

[0111] The preparation methods of Examples 2 and Comparative Examples 1-2 are largely the same as those of Example 1, except for the weight ratio and type of metal components, the thickness of the solder layer, and the soldering temperature.

[0112] The active metal solder substrate materials prepared in the above embodiments and comparative examples were then subjected to peel strength tests, which tested the bonding strength of the solder layer between the copper foil and the ceramic substrate.

[0113] The peel strength test method is based on JIS-C-6481, and the test temperature is 25℃. If the peel strength test result is >200 N / cm, the bonding strength is evaluated as excellent; >100 N / cm, the bonding strength is evaluated as good; within the range of 50 to 100 N / cm, the bonding strength is evaluated as normal; and <50 N / cm, the bonding strength is evaluated as poor.

[0114] Table 1

[0115]

[0116] Test Results and Discussion

[0117] As shown in Table 1, the metal composition of the first solder layer in Examples 1 and 2 is Ag-Cu-Ti, with a weight ratio falling within the range of 50-75:20-48:2-5. The metal composition of the second solder layer is Cu-Sn-Ti, with a weight ratio falling within the range of 55-90:10-40:1-5. Furthermore, the thickness of the first solder layer is not less than 5 micrometers. The peel strength test result of the active metal solder substrate material in Example 1 is greater than 100 N / cm, therefore its bonding strength is evaluated as good; while Example 2 used a lower soldering temperature than Example 1. Unexpectedly, the peel strength test result of the active metal solder substrate material in Example 2 is greater than 200 N / cm, and its bonding strength is evaluated as excellent, significantly higher than the bonding strength of Example 1. In other words, under a specific solder layer composition, moderately reducing the soldering temperature within a certain range will help improve the peel strength of the active metal solder substrate material.

[0118] In Comparative Example 1, both the first and second solder layers used Cu-Sn metals, without using Ag-Cu-Ti or Cu-Sn-Ti. The active metal solder substrate material of Comparative Example 1 showed a peel strength of less than 50 N / cm, thus its bonding strength was assessed as poor. In Comparative Example 2, the combined thickness of the first and second solder layers was 12 micrometers, which was relatively low, resulting in a peel strength of less than 50 N / cm, and therefore a bonding strength assessment of poor.

[0119] Beneficial effects of the embodiments

[0120] The beneficial effects of this application are that the active metal solder substrate material and its manufacturing method provided by this application can effectively reduce the amount of metallic silver used and lower the soldering temperature to below 900°C through the design of the "first solder layer and second solder layer," thereby reducing the impact of high temperature on metal properties and simultaneously reducing material and process costs. More specifically, the second solder layer of this application is disposed between the first solder layer and the conductive metal layer. The second solder layer contains a low-melting-point metal component and does not contain metallic silver (Ag). The second solder layer having a certain thickness can reduce the content of metallic silver in the active metal layer, thereby effectively reducing the material and manufacturing costs of the active metal solder ceramic substrate and effectively improving the electromigration problem caused by silver residue. Finally, the active metal solder substrate material provided by the embodiments of this application can be further used to etch circuit patterns on a ceramic substrate by exposure and development, and can be applied to high-power modules for energy conversion, electric vehicles, and charging systems.

[0121] The content disclosed above is only a preferred and feasible embodiment of this application, and is not intended to limit the scope of the patent application. Therefore, all equivalent technical changes made using the content of this application specification and drawings are included in the scope of the patent application.

Claims

1. An active metal hard solder substrate material, characterized in that... The active metal hard solder substrate material includes: a ceramic substrate layer; An active metal layer comprising: A first solder layer is disposed on one side surface of the ceramic substrate layer; wherein the first solder layer comprises a first metal composite material, comprising: metallic silver (Ag), metallic copper (Cu), and a first active metal component; based on a total weight of 100 parts by weight of the first metal composite material, the content of metallic silver is not less than 50 parts by weight; and A second solder layer is disposed on the surface of the first solder layer away from the ceramic substrate layer; wherein the second solder layer comprises a second metal composite material, comprising: The composition includes a low-melting-point metal component, metallic copper (Cu), and a second active metal component, but does not contain metallic silver (Ag); wherein the melting point of the low-melting-point metal component is between 130°C and 350°C; and based on a total weight of 100 parts by weight of the second metal composite material, the content of the low-melting-point metal component is between 10 parts by weight and 40 parts by weight. Wherein, the sum of the thicknesses of the first solder layer and the second solder layer is at least 12 micrometers, the thickness of the first solder layer is at least 5 micrometers, and the thickness of the second solder layer is at least 10 micrometers; and A conductive metal layer is disposed on the surface of the second solder layer on the side away from the first solder layer.

2. The active metal solder substrate material according to claim 1, characterized in that, The low-melting-point metal component has a content between 5 g·cm⁻¹ -3 Up to 12g·cm -3 The liquid density at its melting point and the resistivity not exceeding 1500 nΩ·m between 0°C and 25°C.

3. The active metal solder substrate material according to claim 1, characterized in that, The low-melting-point metal component is at least one of tin (Sn), bismuth (Bi), indium (In), lead (Pb), and cadmium (Cd).

4. The active metal solder substrate material according to claim 1, characterized in that, The total weight of all metal components in the active metal layer is 100wt%, the content of the low melting point metal component is between 5wt% and 35wt%, the content of the metallic silver is not greater than 45wt%, the total content of the first active metal component and the second active metal component is between 1wt% and 5wt%, and the metallic copper is the balance metal component.

5. The active metal solder substrate material according to claim 1, characterized in that, The content of metallic copper in the second solder layer is higher than the content of the low-melting-point metal component in the second solder layer; and the content of metallic copper in the second solder layer is higher than the content of metallic copper in the first solder layer.

6. The active metal solder substrate material according to claim 1, characterized in that, In the active metal layer, the thickness ratio between the thickness of the first solder layer and the thickness of the second solder layer is between 15% and 50% and 50% and 85%, respectively.

7. The active metal solder substrate material according to claim 1, characterized in that, The first active metal component and the second active metal component are selected from at least one of the material group consisting of titanium, zirconium, tantalum, niobium, vanadium, hafnium, and hydrides of the above metals; wherein the ceramic substrate layer is at least one of silicon nitride ceramic substrate, silicon carbide ceramic substrate, aluminum nitride ceramic substrate, and alumina ceramic substrate; wherein the conductive metal layer is at least one of copper foil, aluminum foil, and copper-aluminum alloy foil.

8. A method for manufacturing an active metal hard solder substrate material, characterized in that, The manufacturing method includes: performing a first solder layer preparation operation, comprising: applying a first active solder paste to one side surface of a ceramic substrate layer and drying it to form a first solder layer; wherein the first active solder paste comprises a first active solder powder, which is composed of metallic silver powder, metallic copper powder and a first active metal powder; wherein, based on 100 parts by weight of the first active solder powder, the content of the metallic silver powder is not less than 50 parts by weight. A second solder layer preparation process includes: applying a second active solder paste to the surface of the first solder layer away from the ceramic substrate layer, and drying it to form a second solder layer; wherein the second active solder paste comprises a second active solder powder, which is composed of a low-melting-point metal powder, copper powder, and a second active metal powder; wherein the low-melting-point metal powder has a melting point between 130°C and 350°C; based on a total weight of 100 parts by weight of the second active solder powder, the content of the low-melting-point metal powder is between 10 parts by weight and 40 parts by weight; wherein the second active solder powder does not contain silver powder; and A conductive metal layer fabrication process is performed, comprising: disposing a conductive metal layer on the surface of the second solder layer away from the first solder layer, and soldering the conductive metal layer to the ceramic substrate layer through an active metal layer composed of the first solder layer and the second solder layer under a vacuum high-temperature sintering process. Wherein, the total thickness of the first hard solder layer and the second hard solder layer is not less than 12 micrometers, the thickness of the first hard solder layer is not less than 5 micrometers, and the thickness of the second hard solder layer is not less than 10 micrometers.

9. The method for manufacturing the active metal solder substrate material according to claim 8, characterized in that, The weight ratio of the silver powder, copper powder, and first active metal powder in the first active solder powder is between 50 and 75: 20 to 48: 2 to 5; the weight ratio of the low-melting-point metal powder, copper powder, and second active metal powder in the second active solder powder is between 10 and 40: 55 to 90: 1 to 5.

10. The method for manufacturing the active metal solder substrate material according to claim 8, characterized in that, The vacuum high-temperature sintering process includes: a first-stage heat treatment process with a temperature not exceeding 500°C and a second-stage heat treatment process with a temperature between 450°C and 900°C.

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