High-heat-conductivity metal brazing copper-clad ceramic substrate and preparation method thereof
By adding specific proportions of Nb, Hf, Ta active components and modified glass fiber to the composite solder, the problem of insufficient thermal conductivity of copper-clad ceramic substrates for metal brazing was solved, and ceramic substrates with high thermal conductivity and high fracture toughness were prepared, thereby improving the heat dissipation and mechanical properties of electronic devices.
Patent Information
- Application Number
- CN202511162765.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-19
- Publication Date
- 2025-11-14
AI Technical Summary
The thermal conductivity of existing metal-brazed copper-clad ceramic substrates is insufficient, which leads to the inability to dissipate heat in a timely manner under high power density scenarios, resulting in excessively high temperatures in electronic devices, performance degradation, and reduced reliability.
By adding specific proportions of Nb, Hf, and Ta active components to the composite solder and modifying the glass fiber, the wettability and interfacial bonding strength of the solder are improved, thus preparing a high thermal conductivity metal brazing copper-clad ceramic substrate.
It significantly improves the thermal conductivity and fracture toughness of metal-brazed copper-clad ceramic substrates, reduces interfacial voids, and enhances heat dissipation efficiency and mechanical strength.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of ceramic substrate technology, specifically to a high thermal conductivity metal-brazed copper-clad ceramic substrate and its preparation method. Background Technology
[0002] Active metal-bonded ceramic substrates are key materials in the field of power semiconductor packaging, widely used in the modern electronics industry, covering high-power semiconductor modules, semiconductor coolers, automotive electronics, and aerospace and military electronic components. In these applications, thermal conductivity is a core indicator determining substrate performance, directly affecting the heat dissipation efficiency of electronic components during operation. However, copper-clad ceramic substrates with metal brazing suffer from insufficient thermal conductivity. When facing high power density scenarios, if the substrate's thermal conductivity is insufficient, heat cannot be dissipated in time, leading to excessively high temperatures in electronic devices, causing performance degradation, reduced reliability, and even serious problems such as device damage. Therefore, it is necessary to propose a high thermal conductivity copper-clad ceramic substrate with metal brazing and its preparation method. Summary of the Invention
[0003] This invention proposes a high thermal conductivity metal-brazed copper-clad ceramic substrate and its preparation method, which solves the problem of low thermal conductivity of metal-brazed copper-clad ceramic substrates in the prior art.
[0004] The technical solution of the present invention is as follows: This invention proposes a high thermal conductivity metal-brazed copper-clad ceramic substrate, comprising, from bottom to top, a ceramic substrate, a composite solder, and a copper sheet. The composite solder, by weight percentage, consists of the following components: Cu 20%~25%, Ti 1%~5%, active component 1.4%~3.5%, with the balance being Ag; the active component is composed of Nb, Hf, and Ta.
[0005] As a further technical solution, the ratio of the active components is (Nb+Hf) / Ta, with a value of 6~13.
[0006] When the (Nb+Hf) / Ta ratio in the active component of the composite solder for metal brazing copper-clad ceramic substrates is less than 6, excessive Ta will cause the composite solder to have an increased melting point and decreased fluidity, making it difficult to fully wet the ceramic substrate and copper sheet, which will easily lead to poor interfacial bonding and increase thermal resistance during heat conduction. When the (Nb+Hf) / Ta ratio is greater than 13, excessive Nb and Hf will easily form too many high-melting-point brittle phases in the solder, making the joint prone to cracking due to stress concentration. When the (Nb+Hf) / Ta ratio is between 6 and 13, the thermal conductivity of the metal brazing copper-clad ceramic substrate can be improved better.
[0007] As a further technical solution, the ratio of Hf to Ta in the active component is 1 to 2.
[0008] When the Hf / Ta ratio in the active component of the composite solder for metal-brazed copper-clad ceramic substrates is less than 1, excessive brittle phases are easily formed, reducing the solder's toughness. When the Hf / Ta ratio is greater than 2, the interfacial activation effect of Ta is weakened, reducing the wettability and bonding strength between the solder and the ceramic. When the Hf / Ta ratio is between 1 and 2, Hf can regulate fluidity and alleviate brittleness, while Ta ensures sufficient activity to promote bonding with the ceramic. This results in solder that is both fully wetted and has a dense interface, while also possessing good mechanical toughness and thermal conductivity, thereby further improving the thermal conductivity of the metal-brazed copper-clad ceramic substrate.
[0009] As a further technical solution, the ceramic matrix comprises the following raw materials in parts by weight: 90-95 parts silicon carbide, 3-5 parts sintering aid, 2-4 parts dispersant, 7-9 parts binder, 3-7 parts modified glass fiber, and 60-70 parts water; wherein the modified glass fiber is obtained by modifying glass fiber with methyl 3-amino-4-ethylbenzoate.
[0010] The addition of glass fibers to the ceramic matrix of copper-clad ceramic substrates for metal brazing has the ability to hinder crack propagation and plays a role in fiber toughening, thereby improving the fracture toughness of the ceramic matrix. However, glass fibers are prone to agglomeration, which prevents their fiber toughening effect from being fully realized. After surface modification of glass fibers with methyl 3-amino-4-ethylbenzoate, the dispersibility of glass fibers can be improved, thereby further improving the fracture toughness of the ceramic matrix of copper-clad ceramic substrates for metal brazing.
[0011] As a further technical solution, the preparation method of the modified glass fiber includes the following steps: dispersing methyl 3-amino-4-ethylbenzoate in anhydrous ethanol, then adding glass fiber and mixing, drying to obtain modified glass fiber.
[0012] As a further technical solution, the mass ratio of methyl 3-amino-4-ethylbenzoate to glass fiber in the raw material of the modified glass fiber is 4~7:93.
[0013] As a further technical solution, the glass fiber has a length of 3~9mm and a diameter of 9~13μm.
[0014] As a further technical solution, the sintering aid includes one or both of magnesium oxide and silicon dioxide.
[0015] As a further technical solution, the dispersant includes one or more of sodium tripolyphosphate, polyacrylamide, and sodium citrate.
[0016] As a further technical solution, the adhesive includes one of polyvinyl alcohol and sodium carboxymethyl cellulose, preferably sodium carboxymethyl cellulose.
[0017] This invention also proposes a method for preparing a ceramic matrix, comprising the following steps: A1. Mix silicon carbide, sintering aid, modified glass fiber, dispersant and water to obtain a mixture; A2. Add a binder to the mixture, mix, cast into shape, and dry to obtain a raw ceramic tile; A3. After drilling holes in the raw ceramic sheet, the ceramic substrate is obtained by surface printing, cutting, sintering, and cooling.
[0018] As a further technical solution, the sintering temperature is 1800~2200℃ and the time is 12~24h.
[0019] This invention also proposes a method for preparing a high thermal conductivity metal-brazed copper-clad ceramic substrate, comprising the following steps: S1. After the components of the composite solder are mixed evenly and melted, a pre-pattern is applied to the ceramic substrate and dried to form a composite solder coating layer. S2. Fix copper sheets onto the dried composite solder coating layer, weld, and remove the copper sheets without composite solder coating to obtain a high thermal conductivity metal brazed copper-clad ceramic substrate.
[0020] As a further technical solution, in step S1, the pre-pattern coating process is a screen printing process, and the mesh count of the screen is 250-300.
[0021] As a further technical solution, in step S2, the welding is vacuum brazing, with a vacuum brazing temperature of 600–900°C, a brazing time of 45–55 minutes, and a vacuum degree of 4.6 × 10⁻⁶. -4 ~5.1×10 -4 Pa.
[0022] The working principle and beneficial effects of this invention are as follows: This invention prepares a high thermal conductivity copper-clad ceramic substrate for metal soldering. By precisely controlling the composition and content of the active components in the composite solder, the thermal conductivity of the copper-clad ceramic substrate for metal soldering can be significantly improved. In the prior art, the solder and the ceramic surface often have many tiny voids due to poor wettability, which greatly increases the thermal resistance during heat conduction. This invention improves the wettability of the solder on the ceramic after melting by adding an active component composed of Nb, Hf, and Ta to the solder, reducing the wetting angle and allowing the solder to spread more smoothly on the ceramic surface. This reduces the porosity between the solder and the ceramic surface, lowers the contact thermal resistance, and further improves the overall thermal conductivity of the copper-clad ceramic substrate for metal soldering. Detailed Implementation
[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0024] In the following examples and comparative examples, silicon carbide had a particle size of 50 nm; magnesium oxide had a particle size of 40 nm; silicon dioxide had a particle size of 20 nm; polyacrylamide had a weight-average molecular weight of 12 million; titanium dioxide had a particle size of 30 nm; polyvinyl alcohol (PVA-1788); sodium carboxymethyl cellulose (LT-011) was purchased from Renqiu Litian Chemical Co., Ltd.; and glass fiber had a length of 3-9 mm and a diameter of 9-13 μm.
[0025] Example 1 A high thermal conductivity metal-bonded copper-clad ceramic substrate comprises, from bottom to top, a ceramic substrate, a composite solder, and a copper sheet. The composite solder, by weight percentage, consists of: Cu 20%, Ti 1%, active component 1.4%, and the balance Ag. The active component comprises 1% Nb, 0.2% Hf, and 0.2% Ta, with the ratio of (Nb+Hf) / Ta being 6. The ratio of Hf to Ta is 1. A method for preparing a ceramic matrix includes the following steps: A1. Mix 90 parts silicon carbide, 3 parts magnesium oxide, 3 parts modified glass fiber, 2 parts sodium tripolyphosphate and 60 parts water to obtain a mixture; A2. Add 7 parts of polyvinyl alcohol to the mixture, mix, cast into shape, and dry to obtain raw ceramic tiles; A3. After drilling holes in the raw ceramic slab, the surface is printed, cut, sintered, and cooled to obtain the ceramic matrix; the sintering temperature is 2000℃ and the time is 15h. The method for preparing modified glass fiber includes the following steps: dispersing methyl 3-amino-4-ethylbenzoate in anhydrous ethanol, then adding glass fiber, mixing for 3 hours, and drying to obtain modified glass fiber; wherein the mass ratio of methyl 3-amino-4-ethylbenzoate to glass fiber is 4:93, and the mass-volume ratio of glass fiber to anhydrous ethanol is 1g:13mL. A method for preparing a high thermal conductivity metal-brazed copper-clad ceramic substrate includes the following steps: S1. After the components of the composite solder are mixed evenly and melted, a pre-pattern is coated onto the ceramic substrate and dried to form a composite solder coating layer; wherein, the pre-pattern coating process is a screen printing process with a screen mesh of 250 mesh. S2. Fix copper sheets onto the dried composite solder coating and perform vacuum brazing. The vacuum brazing temperature is 700℃, the brazing time is 50 minutes, and the vacuum degree is 4.7×10⁻⁶. -4 Pa; remove the copper sheet that is not coated with composite solder to obtain a high thermal conductivity metal brazed copper-clad ceramic substrate.
[0026] Example 2 Compared with Example 1, the only difference in Example 2 is that, in this example, the composite solder, by weight percentage, consists of the following components: Cu 23%, Ti 3%, active component 2.1%, and the balance Ag; the active component consists of 1.5% Nb, 0.3% Hf, and 0.3% Ta, with the ratio of (Nb+Hf) / Ta being 6; and the ratio of Hf to Ta being Hf / Ta being 1. A method for preparing a ceramic matrix includes the following steps: A1. Mix 93 parts silicon carbide, 4 parts magnesium oxide, 5 parts modified glass fiber, 3 parts polyacrylamide and 65 parts water to obtain a mixture; A2. Add 8 parts of sodium carboxymethyl cellulose to the mixture, mix, cast into shape, and dry to obtain raw ceramic tiles; A3. After drilling holes in the raw ceramic slab, the surface is printed, cut, sintered, and cooled to obtain the ceramic matrix.
[0027] Example 3 Compared with Example 1, the only difference in Example 3 is that the composite solder in this example is composed of the following components by weight percentage: Cu 25%, Ti 5%, active component 3.5%, and the balance being Ag; the active component consists of 2.5% Nb, 0.5% Hf, and 0.5% Ta, and the ratio of the active component is (Nb+Hf) / Ta = 6; the ratio of Hf to Ta is Hf / Ta = 1. A method for preparing a ceramic matrix includes the following steps: A1. Mix 95 parts silicon carbide, 5 parts silicon dioxide, 7 parts modified glass fiber, 4 parts sodium citrate and 70 parts water to obtain a mixture; A2. Add 9 parts of sodium carboxymethyl cellulose to the mixture, mix, cast into shape, and dry to obtain raw ceramic tiles; A3. After drilling holes in the raw ceramic slab, the surface is printed, cut, sintered, and cooled to obtain the ceramic matrix.
[0028] Example 4 Compared with Example 2, the only difference in Example 4 is that the active components in the composite solder of this example are composed of 1.35% Nb, 0.45% Hf, and 0.3% Ta, and the ratio of the active components is (Nb+Hf) / Ta is 6; the ratio of Hf and Ta is Hf / Ta is 1.5.
[0029] Example 5 Compared with Example 2, the only difference in Example 5 is that the active components in the composite solder of this example are composed of 1.2% Nb, 0.6% Hf, and 0.3% Ta, and the ratio of the active components is (Nb+Hf) / Ta = 6; the ratio of Hf to Ta is Hf / Ta = 2.
[0030] Example 6 Compared with Example 2, the only difference in Example 6 is that the active components in the composite solder of this example are composed of 1.575% Nb, 0.315% Hf, and 0.21% Ta, and the ratio of the active components is (Nb+Hf) / Ta is 9; the ratio of Hf and Ta is Hf / Ta is 1.5.
[0031] Example 7 Compared with Example 2, the only difference in Example 6 is that the active components in the composite solder of this example are composed of 1.725% Nb, 0.225% Hf, and 0.15% Ta, and the ratio of the active components is (Nb+Hf) / Ta is 13; the ratio of Hf and Ta is Hf / Ta is 1.5.
[0032] Example 8 Compared with Example 2, the only difference in Example 8 is that the mass ratio of methyl 3-amino-4-ethylbenzoate to glass fiber in the modified glass fiber in this example is 5:93.
[0033] Example 9 Compared with Example 2, the only difference in Example 9 is that the mass ratio of methyl 3-amino-4-ethylbenzoate to glass fiber in the modified glass fiber in this example is 7:93.
[0034] Example 10 Compared with Example 2, the only difference in Example 10 is that the modified glass fiber is replaced with an equal amount of glass fiber in this example.
[0035] Comparative Example 1 Compared with Example 2, the only difference in Comparative Example 1 is that the active component in this comparative example composite solder consists only of Nb and Hf in a mass ratio of 5:1.
[0036] Comparative Example 2 Compared with Example 2, the only difference in Comparative Example 2 is that the active component in this comparative example composite solder consists only of Nb and Ta in a mass ratio of 5:1.
[0037] Comparative Example 3 Compared with Example 2, the only difference in Comparative Example 3 is that the active component in this comparative example composite solder consists only of Ta and Hf in a mass ratio of 1:1.
[0038] Comparative Example 4 Compared with Example 2, the only difference in Comparative Example 4 is that the active component in this comparative example composite solder consists only of Nb.
[0039] Comparative Example 5 Compared with Example 2, the only difference in Comparative Example 5 is that the active component in this comparative example composite solder consists only of Hf.
[0040] Comparative Example 6 Compared with Example 2, the only difference in Comparative Example 6 is that the active component in this comparative example composite solder consists only of Ta.
[0041] Comparative Example 7 Compared with Example 2, the only difference of Comparative Example 7 is that it does not contain composite solder.
[0042] The high thermal conductivity metal-bonded copper-clad ceramic substrates prepared in Examples 1-10 and Comparative Examples 1-7 were tested according to the following method: 1. Thermal conductivity test: The thermal conductivity of the copper-clad ceramic substrate was tested according to the test methods specified in standard GB / T36476-2018 "General Specification for Metal-based Copper-clad Foil Laminates for Printed Circuits". 2. Fracture toughness test: The fracture toughness of the ceramic matrix was tested according to the test method specified in standard GB / T23806-2009 "Fine Ceramics Fracture Toughness Test Method - Single-sided Precracked Beam (SEPB) Method"; The measurement results are shown in Tables 1 and 2: Table 1. Thermal conductivity test results of copper-clad ceramic substrates brazed with metal
[0043] As shown in Table 1, the comparison between Examples 1-7 and Comparative Examples 1-7 indicates that the addition of active components Nb, Hf, and Ta to the composite solder can further improve the thermal conductivity of the copper-clad ceramic substrate for metal soldering. The comparison between Examples 2 and 4-7 shows that when the ratio of active components (Nb+Hf) / Ta is 6 and the ratio of Hf / Ta is 1, the thermal conductivity of the copper-clad ceramic substrate for metal soldering can be further improved.
[0044] Table 2. Fracture toughness test results of ceramic matrix
[0045] As shown in Table 2, the comparison between Examples 2, 8-9 and Example 10 indicates that the addition of methyl 3-amino-4-ethylbenzoate modified glass fiber can significantly improve the fracture toughness of the ceramic matrix in the metal brazing copper-clad ceramic substrate.
[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A high thermal conductivity metal-brazed copper-clad ceramic substrate, characterized in that, From bottom to top, it includes a ceramic matrix, a composite solder, and a copper sheet. The composite solder, by weight percentage, consists of the following components: Cu 20%~25%, Ti 1%~5%, active component 1.4%~3.5%, with the balance being Ag; the active component consists of Nb, Hf, and Ta.
2. The high thermal conductivity metal brazing copper-clad ceramic substrate according to claim 1, characterized in that, The ratio of the active components is (Nb+Hf) / Ta, with a value of 6~13.
3. The high thermal conductivity metal-brazed copper-clad ceramic substrate according to claim 2, characterized in that, The ratio of Hf to Ta in the active component is 1 to 2.
4. The high thermal conductivity metal-brazed copper-clad ceramic substrate according to claim 1, characterized in that, The ceramic matrix comprises the following raw materials in parts by weight: 90-95 parts silicon carbide, 3-5 parts sintering aid, 2-4 parts dispersant, 7-9 parts binder, 3-7 parts modified glass fiber, and 60-70 parts water; the modified glass fiber is obtained by modifying glass fiber with methyl 3-amino-4-ethylbenzoate.
5. The high thermal conductivity metal-brazed copper-clad ceramic substrate according to claim 4, characterized in that, The mass ratio of methyl 3-amino-4-ethylbenzoate to glass fiber in the raw material of the modified glass fiber is 4~7:
93.
6. The method for preparing a high thermal conductivity metal-brazed copper-clad ceramic substrate according to claim 4, characterized in that, The glass fiber has a length of 3~9mm and a diameter of 9~13μm.
7. The high thermal conductivity metal-brazed copper-clad ceramic substrate according to claim 4, characterized in that, The sintering aids include one or both of magnesium oxide and silicon dioxide.
8. A high thermal conductivity metal-brazed copper-clad ceramic substrate according to claim 4, characterized in that, The dispersant includes one or more of sodium tripolyphosphate, polyacrylamide, and sodium citrate.
9. A method for preparing a ceramic substrate, used to prepare a high thermal conductivity metal-brazed copper-clad ceramic substrate as described in any one of claims 1 to 8, comprising the following steps: A1. Mix silicon carbide, sintering aid, modified glass fiber, dispersant and water to obtain a mixture; A2. Add a binder to the mixture, mix, cast into shape, and dry to obtain a raw ceramic tile; A3. After drilling holes in the raw ceramic sheet, the ceramic substrate is obtained by surface printing, cutting, sintering, and cooling.
10. A method for preparing a high thermal conductivity metal-brazed copper-clad ceramic substrate, used to prepare a high thermal conductivity metal-brazed copper-clad ceramic substrate as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. After the components of the composite solder are mixed evenly and melted, a pre-pattern is applied to the ceramic substrate and dried to form a composite solder coating layer. S2. Fix copper sheets onto the dried composite solder coating layer, weld, and remove the copper sheets without composite solder coating to obtain a high thermal conductivity metal brazed copper-clad ceramic substrate.