Metal ceramic substrate and its manufacturing method

Abstract

To provide a metal ceramic substrate and a production method therefor.SOLUTION: A metal ceramic substrate contains a ceramic substrate layer, a metal solder layer, and a conductive metallic layer. The metal solder layer contains a first part solder layer and a second part solder layer. The first part solder layer is placed at a side surface of the ceramic substrate layer. A composition of the first part solder layer contains a first metal solder material, and the first metal solder material contains metallic copper and an active metal and does not contain metallic silver. The second part solder layer is placed at a side surface of the first part solder layer. A composition of the second part solder layer contains a second metal solder material. The second metal solder material contains metallic tin and metallic copper and does not contain metallic silver.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Cross-reference to related patent applications This application claims the benefit of priority to Taiwan Patent Application No. 113104612, filed February 6, 2024. The entire contents of the above-identified application are incorporated herein by reference.

[0002]

[0010] Several references, which may include patents, patent applications, and various publications, may be cited and discussed in the description of this disclosure. Citation and / or discussion of such references is provided solely for clarity of explanation of the present disclosure and is not an admission that any such reference is "prior art" to the disclosure described herein. All references cited and discussed herein are incorporated herein by reference in their entirety to the same extent as if each reference were individually incorporated by reference.

[0003] Field of the Disclosure FIELD OF THE DISCLOSURE The present disclosure relates to substrates, and more particularly to metal-ceramic substrates and methods of making same. [Background technology]

[0004] With the promotion of energy conservation and carbon reduction policies in various countries, the global market for electric vehicles (EVs) is currently booming. In recent years, as major automakers have successively launched 800-volt high-voltage vehicle products, the demand for silicon carbide (SiC) ceramic substrate materials has rapidly increased.

[0005] However, the voltage, frequency, and operating temperature requirements for power devices based on silicon carbide (SiC) ceramic substrate materials are constantly increasing, which is why ceramic substrate materials are also being required to improve their heat dissipation and reliability.

[0006] In the related art, conventional direct-bonding-copper (DBC) ceramic substrates are fabricated by eutectic bonding, and no bonding material exists between the copper layer and the ceramic substrate. However, during high-temperature operation, large thermal stress often occurs due to the difference in thermal expansion coefficients between the copper layer and the ceramic substrate (e.g., Al2O3 or AlN). This thermal stress often causes the copper layer to peel off from the surface of the ceramic substrate. Therefore, conventional direct-bonding-copper (DBC) ceramic substrates cannot meet the packaging requirements of high temperature, high power, high heat dissipation, and high reliability.

[0007] Currently, traditional direct copper bonded (DBC) ceramic substrates are gradually being replaced by active metal brazing (AMB) substrate materials. The active metals (e.g., Ti, Zr, Ta, Nb, V, or Hf) in the active metal brazing substrate materials can wet the side surfaces of ceramic substrates, allowing ultra-thick copper foils to be brazed to the ceramic substrates at high temperatures. The brazing layer formed between the ultra-thick copper foil and the ceramic substrate by the active metal brazing process has high bonding strength.

[0008] Conventional active metal bonding paste materials typically use silver-copper-titanium (Ag-Cu-Ti) metal composites, in which the silver content is typically greater than 50 weight percent (weight percent concentration), and may even exceed 70 weight percent.

[0009] The brazing temperature of conventional active metal joining paste materials employing silver-copper-titanium (Ag-Cu-Ti) metal composites is typically above 900°C (e.g., 915°C). Because the brazing layer formed from conventional active metal joining paste materials contains a high amount of silver (i.e., a precious metal), the material and manufacturing costs of active metal joining ceramic substrates remain high. Furthermore, the problem of electromigration due to silver (Ag) residue after the etching process has long been a challenge to be solved. [Prior art documents] [Patent Documents] [Patent Document 1] Chinese Patent No. 114230361B Specification [Patent Document 2] U.S. Patent Application Publication No. 2023 / 0135530A1 [Patent Document 3] U.S. Patent Application Publication No. 2023 / 0187310A1 Summary of the Invention [Problem to be solved by the invention]

[0010] In response to the above-mentioned technical shortcomings, the present disclosure provides a metal-ceramic substrate and a method for manufacturing the same. [Means for solving the problem]

[0011] In order to solve the above problems, one technical aspect adopted by the present disclosure is to provide a metal ceramic substrate. The metal ceramic substrate includes a ceramic substrate layer, a metal solder layer, and a conductive metal layer. The metal solder layer includes a first sub-solder layer and a second sub-solder layer. The first sub-solder layer is disposed on a side (surface) of the ceramic substrate layer. The composition of the first sub-solder layer includes a first metal solder material, which includes metallic copper (Cu) and an active metal, but does not include metallic silver (Ag). The thickness of the first sub-solder layer is greater than 6 micrometers. The second sub-solder layer is disposed on a side of the first sub-solder layer away from the ceramic substrate layer. The composition of the second sub-solder layer includes a second metal solder material, which includes metallic tin (Sn) and metallic copper (Cu), but does not include metallic silver (Ag). The thickness of the second sub-solder layer is greater than 6 micrometers. A conductive metal layer is disposed on the side of the second solder layer remote from the first solder layer.

[0012] Another technical aspect of the present disclosure to solve the above problems is to provide a method for manufacturing a metal-ceramic substrate. The method includes applying a first solder paste to a side surface of a ceramic substrate layer and drying the first solder paste at a high temperature to form a first partial solder layer. The first solder paste includes a first metal solder material and a first organic medium. The first metal solder material includes metallic copper (Cu) and an active metal, but does not include metallic silver (Ag). The first partial solder layer has a thickness greater than 6 micrometers. The method further includes applying a second solder paste to a side surface of the first partial solder layer away from the ceramic substrate layer and drying the second solder paste at a high temperature to form a second partial solder layer. The second solder paste includes a second metal solder material and a second organic medium. The second metal solder material includes metallic tin (Sn) and metallic copper (Cu), but does not include metallic silver (Ag). The second partial solder layer has a thickness greater than 6 micrometers. The method further includes disposing a conductive metal layer on a side of the second solder layer remote from the first solder layer.

[0013] Therefore, in the metal ceramic substrate and manufacturing method thereof provided by the present disclosure, "a first solder layer is disposed on a side of the ceramic substrate layer, the composition of the first solder layer includes a first metal solder material, the first metal solder material includes metallic copper (Cu) and an active metal, and does not include metallic silver (Ag), and the thickness of the first solder layer is greater than 6 micrometers," and "a second solder layer is disposed on a side of the first solder layer away from the ceramic substrate layer, the composition of the second solder layer includes a second metal solder material, the second metal solder material includes metallic tin (Sn) and metallic copper (Cu), and does not include metallic silver (Ag), and the thickness of the second solder layer is greater than 6 micrometers," thereby eliminating the need for the use of metallic silver (Ag) in the metal solder layer of the metal ceramic substrate.

[0014] The metal solder layer, which includes the first and second solder layers, can improve the bonding strength between the ceramic substrate layer and the conductive metal layer. It is worth noting that the metal solder layer does not contain silver (Ag), which effectively avoids the electromigration problem caused by silver residues in related art and reduces manufacturing costs.

[0015] These and other aspects of the present disclosure will become apparent from the following description of the embodiments taken in conjunction with the following drawings and illustrations thereof, variations and modifications of which may be made without departing from the spirit and scope of the novel concepts of the present disclosure. [Brief explanation of the drawings]

[0016] The described embodiments may be better understood with reference to the following description and accompanying drawings.

[0017] [Figure 1] FIG. 1 is a schematic diagram of a metal ceramic substrate according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic diagram showing two metal solder layers formed on either side of a metal ceramic substrate. [Figure 3A] 1A-1C are schematic diagrams illustrating a method for manufacturing a metal ceramic substrate according to an embodiment of the present disclosure. [Figure 3B] 1A-1C are schematic diagrams illustrating a method for manufacturing a metal ceramic substrate according to an embodiment of the present disclosure. [Figure 3C] 1A-1C are schematic diagrams illustrating a method for manufacturing a metal ceramic substrate according to an embodiment of the present disclosure. [Figure 3D] 1A-1C are schematic diagrams illustrating a method for manufacturing a metal ceramic substrate according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present disclosure will be described in more detail in the following examples, which are intended to be merely illustrative, as numerous modifications and variations to the examples will be apparent to those skilled in the art. Like numbers in the drawings refer to like components throughout the drawings. As used throughout this description and the appended claims, the meanings of "a," "an," and "the" include plural references, unless clearly contradicted by context, and the meaning of "in" includes "in" and "on." Headings or sub-headings may be used herein for the convenience of the reader, but shall have no effect on the scope of the disclosure.

[0019] Terms used herein generally have their ordinary meaning in the art. In case of conflict, the present specification, including any definitions provided herein, will control. The same may be expressed in multiple ways. Alternative phrases and synonyms may be used for any term discussed herein, and no special significance is attached to whether a term is recited or discussed herein. A description with one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification, including examples of any term, is merely illustrative and in no way limits the scope and meaning of the present disclosure or the scope and meaning of any exemplified term. Similarly, the present disclosure is not limited to the various embodiments provided herein. While ordinal numbers such as "first," "second," or "third" may be used to describe various components, signals, etc., such terms are merely intended to distinguish one component / signal from another and are not intended to, and should not be construed to, impose any substantial limitations on the components, signals, etc.

[0020] [Metal ceramic substrate] As shown in Figure 1, one embodiment of the present disclosure provides a metal ceramic substrate E. The metal ceramic substrate E includes a ceramic substrate layer 1, a metal solder layer 2, and a conductive metal layer 3. The metal solder layer 2 is disposed between the ceramic substrate layer 1 and the conductive metal layer 3, connecting the ceramic substrate layer 1 and the conductive metal layer 3.

[0021] More specifically, the metal solder layer 2 includes a first partial solder layer 21 and a second partial solder layer 22. The first partial solder layer 21 is disposed on a side surface of the ceramic substrate layer 1, the second partial solder layer 22 is disposed on a side surface of the first partial solder layer 21 remote from the ceramic substrate layer 1, and the conductive metal layer 3 is disposed on a side surface of the second partial solder layer 22 remote from the first partial solder layer 21. In other words, the first partial solder layer 21 and the second partial solder layer 22 are stacked, with the first partial solder layer 21 in contact with the ceramic substrate layer 1 and the second partial solder layer 22 in contact with the conductive metal layer 3.

[0022] In this embodiment, the first solder layer 21, the second solder layer 22, and the conductive metal layer 3 are sequentially disposed on only one side of the ceramic substrate layer 1. However, the present disclosure is not limited to this. For example, as shown in FIG. 2 , in another embodiment of the present disclosure, another first solder layer 21′, another second solder layer 22′, and another conductive metal layer 3′ can be sequentially disposed on the other side of the ceramic substrate layer 1. This allows for the formation of a metal ceramic substrate E′ in which a metal solder layer 2 is disposed on each of both side surfaces of the ceramic substrate layer 1.

[0023] The ceramic substrate layer 1 will now be described in detail.

[0024] The ceramic substrate layer 1 can be 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.

[0025] Preferably, in this embodiment, the ceramic substrate layer 1 is a silicon nitride (SiN) ceramic substrate. In addition, the thickness T1 of the ceramic substrate layer 1 can be, for example, 100 micrometers to 1000 micrometers, but the present disclosure is not limited thereto.

[0026] The first partial solder layer 21 is described in detail below.

[0027] The first solder layer 21 is an active metal layer. The first solder layer 21 is mainly formed of metallic copper (Cu) and contains an active metal. More specifically, the composition of the first solder layer 21 includes a first metallic solder material and a first organic medium. The first metallic solder material includes metallic copper (Cu) and an active metal. Preferably, the first metallic solder material is formed of metallic copper (Cu) and an active metal and does not contain metallic silver (Ag).

[0028] Furthermore, in some embodiments of the present disclosure, the active metal can be selected from the group consisting of titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), vanadium (V), hafnium (Hf), and a metal hydride of any one of the foregoing metals. For example, the metal hydride can be selected from the group consisting of titanium hydride (TiH), zirconium hydride (ZrH), tantalum hydride (TaH), niobium hydride (NbH), vanadium hydride (VH), and hafnium hydride (HHf).

[0029] Preferably, the active metal is at least one of titanium (Ti) and titanium hydride (TiH2).

[0030] The weight percent concentration of the first metal solder material in the first partial solder layer 21 is 70 wt % (weight percent) or more, preferably 80 wt % or more, and more preferably 90 wt % or more.

[0031] Additionally, the ratio of the copper metal (Cu) content to the active metal content, where the total weight of the first metal solder material is 100 weight percent, is in the range of 80%:20% to 50%:50% (i.e., the active metal content is in the range of 20 weight percent to 50 weight percent). Preferably, the ratio of the copper metal (Cu) content to the active metal content is in the range of 65%:35% to 55%:45%. For example, the ratio of the copper metal (Cu) content to the active metal content is 60%:40%. That is, in the first metal solder material, the ratio of the copper metal (Cu) content to the active metal content is greater than 1, but the present disclosure is not limited thereto.

[0032] Furthermore, the thickness T21 of the first partial solder layer 21 is 6 micrometers or more, preferably 8 micrometers or more, and more preferably 10 to 18 micrometers.

[0033] The second partial solder layer 22 is described in more detail below.

[0034] The second partial solder layer 22 is a tin-copper metal layer.

[0035] More specifically, the composition of the second solder layer 22 includes a second metallic solder material and a second organic medium. The second metallic solder material includes metallic tin (Sn) and metallic copper (Cu). Preferably, the second metallic solder material is formed of metallic tin and metallic copper and does not contain metallic silver (Ag).

[0036] The weight percent concentration of the second metal solder material in the second partial solder layer 22 is 70 weight percent or more, preferably 80 weight percent or more, and more preferably 90 weight percent or more.

[0037] Additionally, the ratio of the metallic tin (Sn) content to the metallic copper (Cu) content is in the range of 80%:20% to 30%:70% (i.e., the metallic tin content is in the range of 30% to 80% by weight), where the total weight of the second metallic solder material is 100% by weight. Preferably, the ratio of the metallic tin (Sn) content to the metallic copper (Cu) content is in the range of 80%:20% to 65%:35%. For example, the ratio of the metallic tin content to the metallic copper content is 75%:25%.

[0038] In an exemplary embodiment of the present disclosure, the metallic copper (Cu) content (e.g., 55% to 65%) in the first solder layer 21 is greater than the metallic copper (Cu) content (e.g., 20% to 35%) in the second solder layer 22, but the present disclosure is not limited thereto.

[0039] Furthermore, the thickness T22 of the second partial solder layer 22 is 6 micrometers or more, preferably 8 micrometers or more, and more preferably 10 to 18 micrometers.

[0040] Specifically, the total thickness of the metal solder layer 2 (i.e., the sum of the thickness T21 of the first partial solder layer 21 and the thickness T22 of the second partial solder layer 22) is 12 micrometers or more, preferably 16 micrometers or more, and more preferably 20 micrometers to 36 micrometers.

[0041] The conductive metal layer 3 is described in detail below.

[0042] As shown in FIG. 1, the conductive metal layer 3 is disposed on the side of the second solder layer 22 that is remote from the first solder layer 21 .

[0043] The conductive metal layer 3 can be, for example, a metal copper foil, a metal aluminum foil, or a copper-aluminum alloy foil (i.e., a Cu-Al alloy foil). In this embodiment, the conductive metal layer 3 is preferably a metal copper foil. In addition, the thickness T3 of the conductive metal layer 3 can be, for example, 50 micrometers to 1200 micrometers, but the present disclosure is not limited thereto.

[0044] Due to the configuration of the first solder layer 21 and the second solder layer 22 of the metal solder layer 2, the metal solder layer 2 can improve the bonding strength between the ceramic substrate layer 1 and the conductive metal layer 3. It is worth mentioning that since the metal solder layer 2 does not contain metallic silver (Ag), it can effectively avoid the electromigration problem caused by silver residue in related art and reduce manufacturing costs.

[0045] [Metal-ceramic substrate manufacturing method] The structural and material characteristics of the metal-ceramic substrate have been described above. The method for manufacturing the metal-ceramic substrate of the present disclosure will now be described in detail.

[0046] As shown in FIGS. 3A to 3D, an embodiment of the present disclosure also provides a method for manufacturing a metal-ceramic substrate, including steps S110, S120, S130, and S140.

[0047] 3A, step S110 includes providing a ceramic substrate layer 1. The ceramic substrate layer 1 can be 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. Preferably, the ceramic substrate layer 1 is a silicon nitride (SiN) ceramic substrate.

[0048] As shown in FIG. 3B, step S120 includes applying a first solder paste to the side surface of the ceramic substrate layer 1 and drying the first solder paste at an elevated temperature to form a first partial solder layer 21, thereby removing a substantial amount of the organic solvent in the first solder paste.

[0049] The first solder paste is prepared by mixing a first metal solder material and a first organic medium (e.g., a paste-forming agent, an organic solvent, and a thixotropic agent), and is formulated to have an appropriate viscosity (e.g., 50 mPa·s to 300 mPa·s) so that the first solder paste can be easily applied to the ceramic substrate layer 1.

[0050] For example, the first solder paste can be applied to the side surface of the ceramic substrate layer 1 by screen printing and dried at a high temperature of 90°C to 110°C for 5 to 15 minutes, resulting in the evaporation of most of the organic solvent in the first solder paste and the formation of a first partial solder layer 21 from the first solder paste.

[0051] In some embodiments of the present disclosure, the ratio of the weight of the first metal solder material to the weight of the first organic medium is in the range of 70%:30% to 95%:5%, preferably in the range of 80%:20% to 90%:10%.

[0052] The first metal solder material includes metallic copper (Cu) and an active metal. Preferably, the first metal solder material is formed by metallic copper and an active metal, and does not include metallic silver (Ag).

[0053] When the total weight of the first metal solder material is 100 weight percent, the ratio of the metallic copper (Cu) content to the active metal content is in the range of 80%:20% to 50%:50%. Preferably, the ratio of the metallic copper (Cu) content to the active metal content is in the range of 65%:35% to 55%:45%. For example, the ratio of the metallic copper (Cu) content to the active metal content is 60%:40%.

[0054] In the first organic medium, the ratio of the weight of the paste-forming agent, the weight of the organic solvent, and the weight of the thixotropic agent can be 20% to 30%: 50% to 70%: 1% to 5%.

[0055] The paste-forming agent may be selected from the group consisting of silicone oil, white oil, polyvinyl alcohol, acrylic resin, nitrocellulose, ethylcellulose, dimethyl phthalate, and carboxymethylcellulose. Preferably, the paste-forming agent is ethylcellulose.

[0056] The organic solvent may be selected from 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.

[0057] The thixotropic agent can be at least one selected from the group consisting of polyamide wax, hardened castor oil (hydrogenated castor oil), and polyurea. Preferably, the thixotropic agent is polyamide wax.

[0058] However, the present disclosure is not limited to the above-mentioned embodiments. As long as the metal solder material and the organic medium can be formulated into a solder paste having a viscosity suitable for application to a ceramic substrate (facilitating the formation of a solder layer), the technical solution falls within the spirit and scope of the present disclosure.

[0059] As shown in FIG. 3C, step S130 includes applying a second solder paste to the side of the first partial solder layer 21 away from the ceramic substrate layer 1, and drying the second solder paste at an elevated temperature to remove a substantial amount of the organic solvent in the second solder paste to form a second partial solder layer 22.

[0060] The second solder paste is prepared by mixing a second metal solder material and a second organic medium (e.g., a paste-forming agent, an organic solvent, and a thixotropic agent), and is formulated to have an appropriate viscosity (e.g., 50 mPa·s to 300 mPa·s) so that the second solder paste can be easily applied to the first partial solder layer 21.

[0061] For example, the second solder paste can be applied to the first solder layer 21 by screen printing and dried at a high temperature of 90°C to 110°C for 5 to 15 minutes, resulting in the evaporation of most of the organic solvent in the second solder paste and the formation of the second solder layer 22 from the second solder paste.

[0062] In some embodiments of the present disclosure, the ratio of the weight of the second metal solder material to the weight of the second organic medium is in the range of 70%:30% to 95%:5%, preferably in the range of 80%:20% to 90%:10%.

[0063] The second metal solder material includes metallic tin (Sn) and metallic copper (Cu). Preferably, the second metal solder material is formed by metallic tin and metallic copper, and does not include metallic silver (Ag).

[0064] The ratio of the metallic tin (Sn) content to the metallic copper (Cu) content is in the range of 80%:20% to 30%:70%, where the total weight of the second metallic solder material is 100 weight percent. Preferably, the ratio of the metallic tin (Sn) content to the metallic copper (Cu) content is in the range of 80%:20% to 65%:35%. For example, the ratio of the metallic tin content to the metallic copper content is 75%:25%. The content and material type of the second organic medium in the second solder paste are the same as those in the first solder paste and will not be repeated here.

[0065] As shown in FIG. 3D, step S140 includes placing the conductive metal layer 3 on the side of the second solder layer 22 away from the first solder layer 21 so that the conductive metal layer 3 can be connected to the ceramic substrate layer 1 via the first solder layer 21 and the second solder layer 22.

[0066] The conductive metal layer 3 can be a metallic copper foil, a metallic aluminum foil, or a copper-aluminum alloy foil. In this embodiment, the conductive metal layer 3 is preferably a metallic copper foil.

[0067] Step S140 further includes performing a high-temperature vacuum sintering process to firmly connect the conductive metal layer 3 to the ceramic substrate layer 1 via the metal solder layer 2 formed by the first solder layer 21 and the second solder layer 22.

[0068] The operating temperature of the high temperature vacuum sintering process is 600°C to 900°C, preferably 700°C to 900°C.

[0069] It is worth noting that in the above-mentioned high-temperature vacuum sintering process, the active metal (e.g., Ti) in the first solder layer 21 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 silicon oxide (TiSi), and / or titanium disilicate (TiSi2). This can improve the bonding strength between the conductive metal layer 3 and the ceramic substrate layer 1. In addition, when the metal tin (Sn) and metal copper (Cu) of the second solder layer 22 are heated in the high-temperature vacuum sintering process, the metal tin and metal copper can melt into a fluid state and react with each other, resulting in good bonding strength between the conductive metal layer 3 and the ceramic substrate layer 1.

[0070] For example, when the operating temperature of the high-temperature vacuum sintering process is higher than 600°C, metallic tin can first react with metallic copper to form a Cu3Sn alloy. Furthermore, the Cu3Sn alloy can react with more metallic tin to form a Cu6Sn5 alloy. This allows for a stronger connection between the second solder layer 22 and the conductive metal layer 3, improving the bonding strength between the conductive metal layer 3 and the ceramic substrate layer 1.

[0071] According to the above configuration, the metal solder layer 2 can be used to improve the bonding strength between the ceramic substrate layer 1 and the conductive metal layer 3. It is worth mentioning that the metal solder layer 2 does not contain metallic silver (Ag), which can effectively avoid the electromigration problem caused by silver residue in related technologies and reduce manufacturing costs. [Example]

[0072] [Experimental data and test results] Hereinafter, a detailed description will be given with reference to Examples 1 to 3.

[0073] The preparation method of Example 1 includes applying a first solder paste containing a first metal solder material and a first organic medium to a side surface of a ceramic substrate layer according to the conditions shown in Table 1, and drying the first solder paste at a high temperature (i.e., 100°C) to form a first partial solder layer. The first metal solder material contains copper (Cu) powder and titanium (Ti) powder in a weight ratio of 60:40, and the thickness of the first partial solder layer is 12 micrometers. In addition, the ceramic substrate layer is a silicon nitride ceramic substrate. Next, a second solder paste containing a second metal solder material and a second organic medium is applied to the first partial solder layer and dried at a high temperature (i.e., 100°C) to form a second partial solder layer. The second metal solder material contains tin (Sn) powder and copper (Cu) powder in a weight ratio of 75:25, and the thickness of the second partial solder layer is 12 micrometers. In each of the first and second solder pastes, the weight ratio of the metal solder material to the organic medium is 80:20. In the organic medium, the paste-forming agent is ethyl cellulose, the organic solvent is ethylene glycol butyl ether acetate, and the thixotropic agent is polyamide wax. The weight ratio of the paste-forming agent to the organic solvent to the thixotropic agent is 25:60:15. The first and second solder pastes do not contain metallic silver. Then, a metallic copper foil is further placed on the second partial solder layer to form a metal-ceramic substrate.

[0074] In Example 1, the metal ceramic substrate is further subjected to high-temperature vacuum sintering at a brazing temperature of 855° C. Then, the temperature of the metal ceramic substrate is lowered to room temperature (i.e., 25° C.), and a tensile strength test of the metal ceramic substrate is performed.

[0075] The preparation methods of Examples 2 and 3 are substantially the same as those of Example 1 above, and the differences between them are listed in Table 1 below.

[0076] A tensile strength tester is used to measure the tensile strength between the metal copper foil and the ceramic substrate in accordance with the JIS-C-6481 standard. The measurement temperature is 25°C. If the tensile strength exceeds 100 N / cm, the bond strength is evaluated as good. If the tensile strength is in the range of 50 N / cm to 100 N / cm, the bond strength is evaluated as fair. If the tensile strength is less than 50 N / cm, the bond strength is evaluated as poor.

[0077] [Table 1]

[0078] [Test results and discussion] The test results shown in Table 1 indicate that the tensile strength of the metal ceramic substrate of Example 1 is 106 N / cm. The metal ceramic substrate of Example 1 has better tensile strength performance than the metal ceramic substrates of Examples 2 and 3. Example 1 demonstrates that the first and second solder layers must have specific compositions and be within specific thickness ranges to improve the bonding strength between the metal copper foil and the ceramic substrate layer. The thicknesses of the first and second solder layers in Example 2 are thin (6 μm) and not within the optimal range, so the tensile strength performance of Example 2 is not good. The thickness of the first solder layer in Example 3 is thin (6 μm) and not within the optimal range, so the tensile strength performance of Example 3 is not good.

[0079] It is worth mentioning that the metal ceramic substrate of Example 1 above can still have good tensile strength performance even though the metal solder layer does not contain metallic silver, which is a breakthrough from the limitations of using metallic silver in the active metal layer in the related art.

[0080] [Beneficial Effects of the Embodiments] In conclusion, in the metal ceramic substrate and manufacturing method thereof provided by the present disclosure, "a first solder layer is disposed on a side of the ceramic substrate layer, the composition of the first solder layer includes a first metal solder material, the first metal solder material includes metallic copper (Cu) and an active metal, and does not include metallic silver (Ag), and the thickness of the first solder layer is greater than 6 micrometers," and "a second solder layer is disposed on a side of the first solder layer away from the ceramic substrate layer, the composition of the second solder layer includes a second metal solder material, the second metal solder material includes metallic tin (Sn) and metallic copper (Cu), and does not include metallic silver (Ag), and the thickness of the second solder layer is greater than 6 micrometers," thereby eliminating the need for the use of metallic silver (Ag) in the metal solder layer of the metal ceramic substrate.

[0081] The metal solder layer, which includes the first and second solder layers, can improve the bonding strength between the ceramic substrate layer and the conductive metal layer. It is worth noting that the metal solder layer does not contain silver (Ag), which effectively avoids the electromigration problem caused by silver residues in related art and reduces manufacturing costs.

[0082] Finally, the metal ceramic substrate of the present disclosure can be applied to high-power modules for energy conversion, electric vehicles and charging systems through etching circuit patterns on the ceramic substrate by exposure and development.

[0083] The foregoing description of exemplary embodiments of the present disclosure has been presented for purposes of illustration and description only, and is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching.

[0084] The foregoing embodiments have been chosen and described to explain the principles of the disclosure and their practical application, so as to enable others skilled in the art to utilize the disclosure and various embodiments, with various modifications as may be suitable for the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the disclosure pertains without departing from its spirit and scope. [Explanation of symbols]

[0085] E, E': Metal ceramic substrate 1: Ceramic substrate layer 2: Metal solder layer 21, 21': First solder layer 22, 22': Second partial solder layer 3, 3': Conductive metal layer T1, T21, T22, T3: Thickness

Claims

1. A metal ceramic substrate, a ceramic substrate layer; a metal solder layer; A conductive metal layer and the metal solder layer comprises: a first solder layer disposed on a side of the ceramic substrate layer, the composition of the first solder layer including a first metal solder material, the first metal solder material including metallic copper (Cu) and an active metal and not including metallic silver (Ag), and the thickness of the first solder layer being 8 micrometers or more; and a second solder layer disposed on a side of the first solder layer away from the ceramic substrate layer, the composition of the second solder layer comprising a second metal solder material, the second metal solder material comprising metallic tin (Sn) and metallic copper (Cu) but no metallic silver (Ag), and the thickness of the second solder layer being 8 micrometers or more. wherein the conductive metal layer is disposed on a side of the second solder layer away from the first solder layer.

2. The metal ceramic substrate of claim 1, wherein the ratio of the metallic copper (Cu) content to the active metal content is in the range of 80%:20% to 50%:50%, where the total weight of the first metal solder material is 100 weight percent, and the ratio of the metallic tin (Sn) content to the metallic copper (Cu) content is in the range of 80%:20% to 30%:70%, where the total weight of the second metal solder material is 100 weight percent.

3. The metal ceramic substrate of claim 1, wherein, when the total weight of the first metal solder material is 100 weight percent, the ratio of the content of the metallic copper (Cu) to the content of the active metal is in the range of 65%:35% to 55%:45%, when the total weight of the second metal solder material is 100 weight percent, the ratio of the content of the metallic tin (Sn) to the content of the metallic copper (Cu) is in the range of 80%:20% to 65%:35%, and the entire metal solder layer does not contain metallic silver (Ag).

4. 2. The metal ceramic substrate according to claim 1, wherein the content of metallic copper (Cu) in the first solder layer is greater than the content of metallic copper (Cu) in the second solder layer.

5. 2. The metal ceramic substrate according to claim 1, wherein the thickness of the first solder layer is 10 micrometers to 18 micrometers, and the thickness of the second solder layer is 10 micrometers to 18 micrometers.

6. The active metals include titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), vanadium (V), hafnium (Hf), titanium hydride (TiH ２ ), zirconium hydride (ZrH ２ ), tantalum hydride (TaH ２ ), niobium hydride (NbH), vanadium hydride (VH ２ ), and hafnium hydride (H ２ Hf ２ 2. The metal ceramic substrate of claim 1, wherein the ceramic substrate layer is selected from the group consisting of a silicon nitride ceramic substrate, a silicon carbide ceramic substrate, an aluminum nitride ceramic substrate, and an aluminum oxide ceramic substrate, and the conductive metal layer is selected from the group consisting of a metallic copper foil, a metallic aluminum foil, and a copper-aluminum alloy foil.

7. A method for manufacturing a metal ceramic substrate, comprising: applying a first solder paste to a side surface of a ceramic substrate layer and drying the first solder paste at an elevated temperature to form a first partial solder layer, the first solder paste comprising a first metallic solder material and a first organic medium, the first metallic solder material comprising metallic copper (Cu) and an active metal but not metallic silver (Ag), and the thickness of the first partial solder layer being 8 micrometers or greater; applying a second solder paste to a side of the first solder layer away from the ceramic substrate layer and drying the second solder paste at an elevated temperature to form a second solder layer, the second solder paste comprising a second metallic solder material and a second organic medium, the second metallic solder material comprising metallic tin (Sn) and metallic copper (Cu) but no metallic silver (Ag), and the thickness of the second solder layer being 8 micrometers or greater; disposing a conductive metal layer on a side of the second solder layer remote from the first solder layer; A method comprising:

8. 8. The method of claim 7, wherein the weight percentage concentration of the first metal solder material in the first solder layer is 70% by weight or more, and the weight percentage concentration of the second metal solder material in the second solder layer is 70% by weight or more.

9. The method of claim 8, wherein, when the total weight of the first metal solder material is 100 weight percent, the ratio of the content of metallic copper (Cu) to the content of the active metal is in the range of 80%:20% to 50%:50%, and when the total weight of the second metal solder material is 100 weight percent, the ratio of the content of metallic tin (Sn) to the content of metallic copper (Cu) is in the range of 80%:20% to 30%:70%.

10. 9. The method of claim 8, further comprising: performing a high-temperature vacuum sintering process to firmly connect the conductive metal layer to the ceramic substrate layer through a metal solder layer formed by the first partial solder layer and the second partial solder layer, wherein the operating temperature of the high-temperature vacuum sintering process is 600°C to 900°C.

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