Active metal brazing substrate material and manufacturing method thereof

Abstract

The invention discloses an active metal brazing substrate material and a manufacturing method thereof. The substrate material comprises a ceramic substrate layer, a first hard welding layer, a second hard welding layer and a conductive metal layer which are stacked in sequence. The first braze layer includes a first metal composite material including metallic silver (Ag), metallic copper (Cu), and a first active metal component. Based on 100 parts by weight of the total weight of the first metal composite material, the content of silver is not less than 50 parts by weight. The second brazing layer includes a second metal composite material including a low-melting-point metal component, a metal copper, and a second active metal component, and does not include a metal silver. The melting point of the low-melting-point metal component ranges from 130 DEG C to 350 DEG C. Based on 100 parts by weight of the total weight of the second metal composite material, the content of the low-melting-point metal component is 10-40 parts by weight. Therefore, the use amount of the metal silver is effectively reduced, and the brazing temperature is reduced to below 900 DEG C, so that the influence of high temperature on the metal performance is reduced, and the material cost and the manufacturing cost are reduced at the same time.

Description

Technical Field

[0001] The present application relates to a substrate material, and in particular to an active metal brazing (AMB) substrate material and a manufacturing method thereof. Background Art

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

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

[0004] The widely used direct-bonding-copper (DBC) ceramic substrate is prepared by eutectic bonding, and there is no bonding material between the copper layer and the ceramic substrate. However, during high-temperature operation, due to the different thermal expansion coefficients between the copper layer and the ceramic substrate (such as Al2O3 or AlN), large thermal stress is often generated, causing the copper layer to peel off from the surface of the ceramic substrate. Therefore, traditional direct-bonding-copper ceramic substrates have been unable 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 brazing substrate materials utilize the properties of active metal elements (such as Ti, Zr, Ta, Nb, V, Hf, etc.) that can wet the surface of ceramic substrates to braze the ultra-thick copper foil onto the ceramic substrate at high temperatures. The brazing layer formed between the copper layer and the ceramic substrate by the active metal brazing process has a higher connection strength.

[0007] Among the common active metal brazing paste materials, silver-copper-titanium (Ag-Cu-Ti) is a commonly used metal composite material. In the above silver-copper-titanium metal composite material, the silver content is usually more than 50% (weight percentage concentration), and even up to 70%.

[0008] Generally, the brazing temperature of Ag-Cu-Ti used for active metal brazing paste materials usually needs to reach above 900°C (e.g., 915°C). The solder layer formed by the above active metal brazing contains a large amount of metallic silver (precious metal), which makes the material cost and manufacturing cost of active metal brazing ceramic substrates high. Furthermore, the electromigration problem caused by the metallic silver remaining after the etching process has always been a problem that needs to be solved. Summary of the invention

[0009] The technical problem to be solved by the present application is to provide an active metal brazing (AMB) substrate material and a manufacturing method thereof in view of the deficiencies in the prior art, which 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 at the same time reducing material costs and process costs.

[0010] The present application discloses an active metal brazing substrate material, comprising: a ceramic substrate layer; an active metal layer, comprising: a first brazing layer, which is arranged on a side surface of the ceramic substrate layer; wherein the composition of the first brazing layer comprises a first metal composite material, which comprises: metal silver (Ag), metal copper (Cu) and a first active metal component; based on the total weight of the first metal composite material being 100 parts by weight, the content of the metal silver is not less than 50 parts by weight; and a second brazing layer, which is arranged on a side surface of the first brazing layer away from the ceramic substrate layer; wherein the composition of the second brazing layer comprises a second metal composite material, which comprises: low melting point gold The invention relates to a composite material comprising a low-melting-point metal component, a metal copper (Cu), and a second active metal component, and does not contain metal silver (Ag); wherein the melting point of the low-melting-point metal component is between 130°C and 350°C; and based on the total weight of the second metal composite material being 100 parts by weight, 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 hard solder layer and the second hard solder layer is at least not less than 12 microns, the thickness of the first hard solder layer is not less than 5 microns, and the thickness of the second hard solder layer is not less than 10 microns; and a conductive metal layer, which is arranged on a surface of the second hard solder layer on one side away from the first hard solder layer.

[0011] Optionally, the low melting point metal component has a value between 5 g·cm -3 Up to 12 g·cm -3 The liquid density at a melting point between 0°C and 25°C is not greater than 1500nΩ·m.

[0012] Optionally, the low melting point metal component is at least one of metal tin (Sn), metal bismuth (Bi), metal indium (In), metal lead (Pb), and metal 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 is between 5wt% and 35wt%, the content of the metallic silver is not more 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 remaining metal component.

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

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

[0016] Optionally, the first active metal component and the second active metal component are respectively 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 a silicon nitride ceramic substrate, a silicon carbide ceramic substrate, an aluminum nitride ceramic substrate and an aluminum oxide ceramic substrate; wherein the conductive metal layer is at least one of a metal copper foil, a metal aluminum foil and a copper-aluminum alloy foil.

[0017] The present application also discloses a method for manufacturing an active metal brazing substrate material, which comprises: implementing a first brazing layer preparation operation, comprising: applying a first active solder paste on a side surface of a ceramic substrate layer, and drying to form a first brazing layer; wherein the first active solder paste comprises a first active solder powder, which is composed of metal silver powder, metal 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 metal silver powder is not less than 50 parts by weight; implementing a second brazing layer preparation operation, comprising: applying a second active solder paste on a side surface of the first brazing layer away from the ceramic substrate layer, and drying to form a second brazing layer; wherein the second active solder paste comprises a first active solder powder, which is composed of metal silver powder, metal 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 metal silver powder is not less than 50 parts by weight; Two active solder powders, which are composed of low-melting-point metal powder, metal copper powder and second active metal powder; wherein the low-melting-point metal powder has a melting point between 130°C and 350°C; based on the total weight of the second active solder powder being 100 parts by weight, 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 metal silver powder; and implementing a conductive metal layer preparation operation, which includes: disposing a conductive metal layer on a side surface of the second brazing layer away from the first brazing layer, and brazing the conductive metal layer on the ceramic substrate layer through an active metal layer composed of the first brazing layer and the second brazing layer under a vacuum high-temperature sintering process.

[0018] The total thickness of the first hard solder layer and the second hard solder layer is at least 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 metal silver powder in the first active solder powder; the metal copper powder: the first active metal powder is between 50-75:20-48:2-5; the weight ratio of the low-melting-point metal powder in the second active solder powder; the metal copper powder: the second active metal powder is between 10-40:55-90:1-5.

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

[0021] In summary, the beneficial effect of the present application lies in that the active metal brazing substrate material and the manufacturing method thereof provided in the present application can effectively reduce the amount of metal silver used and reduce the brazing temperature to below 900°C through the design of the "first brazing layer and the second brazing layer", thereby reducing the impact of high temperature on metal properties and at the same time reducing material costs and process costs.

[0022] More specifically, the second brazing layer of the present application is disposed between the first brazing layer and the conductive metal layer. The second brazing layer contains a low melting point metal component and does not contain metallic silver (Ag). The second brazing layer has a certain thickness which can reduce the content of metallic silver in the active metal layer, so as to effectively reduce the material cost and manufacturing cost of the active metal brazing ceramic substrate, and can effectively improve the electromigration problem caused by silver residue. Finally, the active metal brazing substrate material provided in the embodiment of the present application can further be used to etch a circuit pattern on a ceramic substrate by exposure and development, and can be applied to high-power modules for energy conversion, electric vehicles, and charging systems, etc.

[0023] To further understand the features and technical contents of the present application, please refer to the following detailed description and drawings of the present application. However, such description and drawings are only used to illustrate the present application and are not intended to limit the scope of protection of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of an active metal brazing substrate material according to an embodiment of the present application.

[0025] Figure 2 It is a schematic diagram of a ceramic substrate having active metal layers on both sides of the surface.

[0026] FIG. 3A to FIG. 3D Schematic diagram of the manufacturing process of the substrate material according to the embodiment of the present application. DETAILED DESCRIPTION

[0027] The following is an explanation of the embodiments disclosed in the present application through specific embodiments. Those skilled in the art can understand the advantages and effects of the present application from the contents disclosed in this specification. The present application can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present application. In addition, the drawings of the present application are only simple schematic illustrations and are not depicted according to actual sizes. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present application in detail, but the disclosed contents are not intended to limit the scope of protection of the present application.

[0028] It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another component, or one signal from another signal.

[0029] In addition, the term "or" used herein may include any one or more combinations of the associated listed items as appropriate.

[0030] Active Metal Brazing Substrate Materials

[0031] See also Figure 1 As shown, the embodiment of the present application provides an active metal brazing 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 brazing layer 21 and a second brazing layer 22 .

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

[0034] It is worth mentioning that although the first brazing layer 21, the second brazing layer 22 and the conductive metal layer 3 are sequentially disposed on one side surface of the ceramic substrate layer 1 in this embodiment, the present application is not limited thereto. Figure 2 As shown, in another embodiment of the present application, another first brazing layer 21', another second brazing layer 22', and another conductive metal layer 3' may also 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] Further, 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 aluminum oxide (Al2O3) ceramic substrate. In the present embodiment, the ceramic substrate layer 1 is preferably a silicon nitride (SiN) ceramic substrate. In addition, the thickness T1 of the ceramic substrate layer 1 may be, for example, between 100 microns and 1000 microns, but the present application is not limited thereto.

[0037] First brazing layer

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

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

[0040] Furthermore, in some embodiments of the present application, the first active metal component may be, for example, at least one selected from 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 the present application, the first active metal component is preferably at least one of titanium (Ti) and titanium hydride (TiH2). Accordingly, the first brazing layer 21 may also be referred to as a silver-copper-titanium brazing layer (Ag-Cu-Tipaste).

[0043] In terms of content range, the first metal composite material is the main component of the first brazing layer 21. For example, the weight percentage concentration of the first metal composite material in the first brazing layer 21 is at least not less than 80 wt%, and preferably not less than 90 wt%.

[0044] Specifically, in the first brazing layer 21, based on 100 parts by weight of the total weight of the first metal composite material, the content of the metal silver (Ag) is at least not less than 50 parts by weight, and preferably between 50 parts by weight and 75 parts by weight. In terms of thickness range, the thickness T21 of the first brazing layer 21 is at least not less than 5 micrometers, and preferably between 5 micrometers and 24 micrometers.

[0045] According to the above configuration, since the first brazing layer 21 in contact with the ceramic substrate layer 1 contains a certain content of silver (Ag) or more and has a thickness above a certain range, the bonding strength between the ceramic substrate layer 1 and the conductive metal layer 3 can be improved. If the silver (Ag) content in the first brazing layer 21 is too low or the thickness is too thin, the first brazing layer 21 will not allow the active metal brazing substrate material 100 to exert its proper physical properties. If the silver (Ag) content in the first brazing layer 21 is too high or the thickness is too thick, the material cost and manufacturing cost of the active metal brazing substrate material 100 will be too high.

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

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

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

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

[0050] Second brazing layer

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

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

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

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

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

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

[0057] Furthermore, the above-mentioned low melting point metal components all have an electrical resistivity of no more than 1500 nΩ·m between 0° C. and 25° C., and are therefore suitable for use as conductive welding materials.

[0058] Further, similar to the first active metal component, the second active metal component may be, for example, at least one selected from the group consisting of titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), vanadium (V), hafnium (Hf) and hydrides of the above metals. The hydride of the metal 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 a specific embodiment of the present application, the low melting point metal component is tin (Sn), and the second active metal component is titanium (Ti). Accordingly, the second brazing layer 22 can also be called Sn-Cu-Ti brazing layer (Sn-Cu-Ti paste).

[0060] In terms of content range, the second metal composite material is the main component of the second brazing layer 22. For example, the weight percentage concentration of the second metal composite material in the second brazing layer 22 is at least not less than 80 wt%, and preferably not less than 90 wt%.

[0061] Further, in the second brazing layer 22, based on the total weight of the second metal composite material being 100 parts by weight, 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 metal 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 the present application, the content of the metal copper in the second brazing 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 brazing layer 22 (e.g., 10 to 40 parts by weight). In addition, the content of the metal copper in the second brazing layer 22 (e.g., 55 to 90 parts by weight) is higher than the content of the metal copper in the first brazing layer 21 (e.g., 10 to 40 parts by weight).

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

[0064] It is worth mentioning that the low melting point metal component in the second brazing layer 22 can react with metal copper (Cu) during the vacuum sintering process. For example, the low melting point metal component is tin (such as Sn) as an example. When the heating temperature is greater than the melting point of tin (such as greater than 240°C), tin will melt first and in the case of excess copper, tin and copper will first form a Cu3Sn alloy, which will exist in the second brazing layer 22 and at the interface between the second brazing layer 22 and the conductive metal layer 3 (such as copper foil). Furthermore, the Cu3Sn alloy will react with more tin to form a Cu6Sn5 alloy. Thereby, the second brazing layer 22 can be more tightly combined with the conductive metal layer 3.

[0065] Furthermore, the second metal composite material of the second brazing layer 22 can be formed, for example, by mixing and vacuum sintering low melting point metal powder, copper metal powder (Cu metal powder) and active metal powder (such as Ti metal powder). In addition, the second active metal component (such as Ti) in the second brazing layer 22 can diffuse to the ceramic substrate layer 1 through the first brazing layer 21 during the vacuum sintering process, and react with the ceramic material (such as SiN) to form a compound 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 thickness T21 of the first brazing layer 21 and the thickness T22 of the second brazing layer 22) is at least not less than 12 microns, and preferably at least not less than 15 microns, and particularly preferably between 15 microns and 32 microns. The thickness ratio between the thickness T21 of the first brazing layer 21 and the thickness T22 of the second brazing layer 22 is preferably 15% to 50%: 50% to 85% (and the total is 100%), and particularly preferably 20% to 45%: 55% to 80%.

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

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

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

[0071] Furthermore, in some embodiments of the present application, the active metal layer 2 can be brazed at a brazing temperature not greater than 900° C. due to the increased content of the low melting point metal. In a specific embodiment, the brazing temperature of the active metal layer 2 is heated to 450° C. to 900° C., but is not limited thereto. Accordingly, since the active metal layer 2 has a lower brazing temperature than the prior art, the influence of high temperature on metal properties can be effectively improved.

[0072] Conductive metal layer

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

[0074] In addition, the thickness T3 of the conductive metal layer 3 may be, for example, between 50 micrometers and 800 micrometers, but the present application is not limited thereto.

[0075] It is worth mentioning that the conductive metal layer 3 (e.g., oxygen-free copper) can be brazed on the ceramic substrate layer 1 through the active metal layer 2 by vacuum high-temperature sintering. For example, the vacuum high-temperature sintering process can include a first-stage heat treatment process and a second-stage heat treatment process. The temperature condition of the first-stage heat treatment process is not greater than 500°C, and the temperature condition of the second-stage heat treatment process is between 450 and 900°C (i.e., the brazing temperature range).

[0076] According to the above configuration, the active metal brazing substrate material provided in the embodiment of the present application can effectively reduce the amount of metal silver used and reduce the brazing temperature to below 900°C, thereby reducing the impact of high temperature on metal properties and at the same time reducing material costs and process costs.

[0077] It is worth mentioning that the "braze temperature" of the active metal layer 2 referred to in this article refers to the temperature that can make the metal component melt and have sufficient fluidity so as to wet the surface of the workpiece (such as a ceramic substrate). Generally speaking, the temperature of welding temperature higher than 450°C is called the braze temperature. The braze temperature can be, for example, determined by the desired braze temperature and the ternary metallographic diagram composed of three metal components to determine the appropriate weight percentage concentration of each of the metal materials. Alternatively, the ternary metallographic diagram composed of three metal components can be used to find the appropriate braze temperature range through the known weight percentage concentrations of the metal materials. For example, the appropriate braze temperature is a temperature higher than the liquidus phase temperature of the ternary metal component of the braze filler, which can allow the braze filler to have sufficient fluidity, but the present application is not limited to this.

[0078] Method for manufacturing active metal brazing substrate material

[0079] The above is a description of the structural characteristics and material characteristics of the active metal brazing substrate material, and the following will continue to describe the manufacturing method of the active metal brazing substrate material of the present application.

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

[0081] like Figure 3A As shown, the step S110 is to provide a ceramic substrate layer 1. 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 aluminum oxide (Al2O3) ceramic substrate.

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

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

[0084] The first active solder paste is prepared by mixing the first active solder powder and organic components (such as a paste, an organic solvent and a thixotropic agent), and is adjusted to a suitable viscosity (such as 50 to 300 mPa·s) so that the solder paste can be easily coated on the ceramic substrate layer 1.

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

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

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

[0088] Among them, 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 the present application is not limited thereto.

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

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

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

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

[0093] However, the present application is not limited to the above-mentioned implementation mode. As long as the active solder powder and the organic component can be formulated into an active solder paste with a viscosity suitable for coating on the ceramic substrate to facilitate the formation of a hard solder layer, it complies with the protection spirit of the present application and falls within the protection scope of the present application.

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

[0095] The second active solder paste is prepared by mixing the second active solder powder and the organic component to a suitable viscosity (eg, 50-300 mPa·s) so as to be coated on the first brazing layer 21 .

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

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

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

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

[0100] The ratio and material types of the organic components in the second active solder paste are similar to those of the organic components in the first active solder paste, and are not elaborated herein.

[0101] like Figure 3D As shown, the step S140 is to implement a conductive metal layer preparation operation, which includes: disposing a conductive metal layer 3 on a side surface of the second brazing layer 22 away from the first brazing layer 21, and brazing the conductive metal layer 3 on the ceramic substrate layer 1 through an active metal layer 2 composed of the first brazing layer 21 and the second brazing layer 22 under a vacuum high temperature sintering process. The conductive metal layer 3 can be, for example, a metal copper foil, a metal aluminum foil or a copper-aluminum alloy foil.

[0102] The vacuum high temperature sintering treatment process may include, for example, a first stage heat treatment process and a second stage heat treatment process, wherein the temperature condition of the first stage heat treatment process is not greater than 500°C, and the temperature condition of the second stage heat treatment process is between 450°C and 900°C (i.e., the brazing temperature range), which is greater than the temperature condition of the first stage heat treatment process.

[0103] More specifically, the temperature condition of the first stage heat treatment program is between 300°C and 500°C, and the treatment time is between 30 minutes and 60 minutes. The temperature condition of the second stage heat treatment program is between 450°C and 900°C (need to be within the appropriate brazing temperature range), and the treatment time is between 60 minutes and 240 minutes. In addition, the heating rate of the above heat treatment program can be, for example, 5 to 30°C / min. The cooling rate after the 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 brazing layers will at least partially vaporize, and the first and second active metal components (such as Ti) can wet the surface of the ceramic substrate layer 1 and react with the ceramic material (such as SiN) to form compounds such as titanium nitride (TiN), titanium silicide (TiSi), or titanium disilicide (TiSi2) to enhance the bonding strength between the active metal layer 2 and the ceramic substrate layer 1. In addition, the second brazing layer 22 can react with the metal components of the conductive metal layer 3 (such as copper) at the interface at the micron level (such as eutectic reaction between tin and copper) to form 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 brazing layer 21 and the thickness T22 of the second brazing layer 22) is at least not less than 12 microns, preferably at least not less than 15 microns, and particularly preferably between 15 microns and 32 microns. Furthermore, a thickness ratio of the thickness T21 of the first brazing layer 21 to the thickness T22 of the second brazing layer 22 is between 15% and 50%: 50% and 85% (and the total is 100%).

[0106] In addition, based on the total weight of all metal components in the active metal layer 2 being 100wt%, the content of the low melting point metal component is between 5wt% and 35wt%, preferably between 10wt% and 35wt%. The content of the metal silver (Ag) is not more than 45wt%, and preferably between 15wt% and 45wt%. Furthermore, the total content of the first and second active metal components (such as titanium metal) is between 1wt% and 5wt%, preferably between 2wt% and 4wt%. The metal copper (Cu) is the remaining metal component.

[0107] Accordingly, the technical solution provided in the embodiment of the present application can reduce the amount of metallic silver used and reduce the brazing 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 the present application will be described in detail with reference to Examples 1-2 and Comparative Examples 1-2. The Examples are experimental groups that can prove the technical effects of the present application, while the Comparative Examples are groups with poorer conditions. However, the following Examples are only used to help understand the present application, but the present application is not limited thereto.

[0110] Example 1: According to the conditions of Table 1, an active metal brazing substrate material including a first brazing layer and a second brazing layer is prepared. The preparation method comprises: 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) on the surface of a ceramic substrate, and after high-temperature drying, the first brazing layer is formed. Then, a second active solder paste containing 75 parts by weight of copper powder (Cu), 23 parts by weight of a low-melting-point metal powder (tin Sn powder in this embodiment), and 2 parts by weight of titanium powder (Ti) is applied on the first brazing layer, and after high-temperature drying, the second brazing layer is formed. Then, a metal copper foil is further disposed on the second brazing layer to form a laminated material, and then the laminated material is subjected to vacuum high-temperature sintering to finally form an active metal brazing substrate material. In Example 1, the temperature condition of the first stage hot brazing temperature in vacuum high-temperature sintering is 650°C, and the processing time is 30 minutes. The temperature condition of the second stage hot brazing temperature is 900°C, and the processing time is 60 minutes. That is, the brazing temperature is 650-900°C. In addition, the ceramic substrate is a silicon nitride (SiN) ceramic substrate with a thickness of 320 microns. The thickness of the first brazing layer is 6 microns, the thickness of the second brazing layer is 12 microns, and the thickness of the metal copper foil is 500 microns.

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

[0112] Then, the active metal brazing substrate materials prepared in the above-mentioned embodiments and comparative examples were subjected to a peel strength test, which is to test the bonding strength of the brazing layer between the metal copper foil and the ceramic substrate.

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

[0114] Table 1

[0115]

[0116] Test Results and Discussion

[0117] From the test results in Table 1, it can be seen that the metal components of the first brazing layer of Examples 1 to 2 are Ag-Cu-Ti, and the weight ratios are all within the range of 50-75:20-48:2-5. The metal components of the second brazing layer are Cu-Sn-Ti, and the weight ratios are all within the range of 55-90:10-40:1-5. In addition, the thickness of the first brazing layer is not less than 5 microns. The peel strength test result of the active metal brazing substrate material of Example 1 is greater than 100N / cm, so its bonding strength is evaluated as good; while Example 2 uses a lower brazing temperature than Example 1. It was unexpectedly found that the peel strength test result of the active metal brazing substrate material of Example 2 is greater than 200N / cm, and its bonding strength is evaluated as excellent, which is significantly higher than the bonding strength of Example 1. That is to say, under a specific brazing layer composition, reducing the brazing temperature within a moderate range will help to improve the peel strength of the active metal brazing substrate material.

[0118] The metal components used in the first brazing layer and the second brazing layer of Comparative Example 1 are both Cu-Sn, and Ag-Cu-Ti or Cu-Sn-Ti is not used. The active metal brazing substrate material of Comparative Example 1 has a peel strength test result of less than 50N / cm, so the bonding strength is evaluated as poor. The total thickness of the first brazing layer and the second brazing layer of Comparative Example 2 is 12 microns, and the total thickness is low, resulting in a peel strength test result of less than 50N / cm, so the bonding strength is evaluated as poor.

[0119] Advantageous Effects of Embodiments

[0120] The beneficial effect of the present application is that the active metal brazing substrate material and the manufacturing method thereof provided by the present application can effectively reduce the amount of metallic silver through the design of the "first brazing layer and the second brazing layer", and reduce the brazing temperature to below 900°C, thereby reducing the influence of high temperature on metal properties, and at the same time reducing the material cost and process cost. More specifically, the second brazing layer of the present application is arranged between the first brazing layer and the conductive metal layer. The second brazing layer contains a low melting point metal component and does not contain metallic silver (Ag). The second brazing layer has a certain thickness and can reduce the content of metallic silver in the active metal layer, so as to effectively reduce the material cost and manufacturing cost of the active metal brazing ceramic substrate, and can effectively improve the electromigration problem caused by silver residue. Finally, the active metal brazing substrate material provided in the embodiment of the present application can further etch a circuit pattern on the ceramic substrate by exposure and development, and can be applied to high-power modules, electric vehicles and charging systems for energy conversion.

[0121] The contents disclosed above are only preferred feasible embodiments of the present application, and are not intended to limit the scope of the present patent application. Therefore, all equivalent technical changes made using the description and drawings of the present application are included in the scope of the present patent application.

Claims

1. An active metal brazing substrate material, characterized in that The active metal brazing substrate material comprises: a ceramic substrate layer; An active metal layer comprising: a first brazing layer disposed on one side surface of the ceramic substrate layer; wherein the first brazing layer comprises a first metal composite material, comprising: metal silver (Ag), metal copper (Cu) and a first active metal component; based on 100 parts by weight of the total weight of the first metal composite material, the content of the metal silver is not less than 50 parts by weight; and A second brazing layer is disposed on a surface of the first brazing layer away from the ceramic substrate layer; wherein the second brazing layer comprises a second metal composite material, including: A low melting point metal component, metal copper (Cu), and a second active metal component, and no metal silver (Ag) is included; wherein the melting point of the low melting point metal component is between 130° C. and 350° C.; and based on the total weight of the second metal composite material being 100 parts by weight, 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 thickness of the first brazing layer and the second brazing layer is at least not less than 12 micrometers, the thickness of the first brazing layer is not less than 5 micrometers, and the thickness of the second brazing layer is not less than 10 micrometers; and A conductive metal layer is disposed on a surface of the second brazing layer that is away from the first brazing layer.

2. The active metal brazing substrate material according to claim 1, characterized in that: The low melting point metal component has a value between 5 g·cm -3 Up to 12 g·cm -3 The liquid density at a melting point between 0°C and 25°C is not greater than 1500nΩ·m.

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

4. The active metal brazing substrate material according to claim 1, characterized in that: 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 is between 5wt% and 35wt%, the content of the metal silver is no more than 45wt%, the total content of the first active metal component and the second active metal component is between 1wt% and 5wt%, and the metal copper is the remaining metal component.

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

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

7. The active metal brazing substrate material according to claim 1, characterized in that: The first active metal component and the second active metal component are respectively 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 a silicon nitride ceramic substrate, a silicon carbide ceramic substrate, an aluminum nitride ceramic substrate and an aluminum oxide ceramic substrate; wherein the conductive metal layer is at least one of a metal copper foil, a metal aluminum foil, and a copper-aluminum alloy foil.

8. A method for manufacturing an active metal brazing substrate material, characterized in that: The manufacturing method comprises: performing a first brazing layer preparation operation, including: coating a first active solder paste on a side surface of a ceramic substrate layer, and drying the first brazing layer; wherein the first active solder paste comprises a first active solder powder, which is composed of a metal silver powder, a metal 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 metal silver powder is not less than 50 parts by weight; Implementing a second brazing layer preparation operation, comprising: coating a second active solder paste on a surface of the first brazing layer away from the ceramic substrate layer, and drying the coating to form a second brazing layer; wherein the second active solder paste comprises a second active solder powder, which is composed of a low melting point metal powder, a metal 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 100 parts by weight of the total 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 metal silver powder; and Implementing a conductive metal layer preparation operation, which includes: disposing a conductive metal layer on a surface of the second brazing layer away from the first brazing layer, and brazing the conductive metal layer on the ceramic substrate layer through an active metal layer composed of the first brazing layer and the second brazing layer under a vacuum high-temperature sintering process; The total thickness of the first hard solder layer and the second hard solder layer is at least 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 an active metal brazing substrate material according to claim 8, characterized in that: The weight ratio of the metal silver powder in the first active solder powder; the metal copper powder: the first active metal powder is between 50-75:20-48:2-5; the weight ratio of the low melting point metal powder in the second active solder powder; the metal copper powder: the second active metal powder is between 10-40:55-90:1-5.

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

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