An active solder paste composition for ceramic copper clad, a method for ceramic copper clad, and a copper clad ceramic

Abstract

The present disclosure relates to a kind of active solder paste composition for ceramic copper clad, ceramic copper clad method and copper clad ceramic, with the total weight of active solder paste composition as basis, active solder paste composition contains 1-20wt% first metal powder, 75-94wt% second metal powder and the balance of flux;Wherein, first metal powder contains titanium hydride, and second metal powder contains copper phosphorus silver alloy.The active solder paste composition provided by the present disclosure not only can reduce the silver content, but also can reduce the welding temperature, while also increasing the connection strength of Ti and Cu, increase the welding strength, so that material is not easy to occur segregation.

Description

Technical Field

[0001] This disclosure relates to the field of ceramic copper cladding technology, specifically to an active solder paste composition for ceramic copper cladding, a method for ceramic copper cladding, and copper-clad ceramics. Background Technology

[0002] Common technologies for ceramic copper cladding include direct copper cladding (DBC) and active brazing (AMB). DBC ceramic copper cladding substrates have low reliability and are only suitable for alumina ceramics. AMB substrates utilize a small amount of active elements to react with the ceramic to achieve the connection between copper and ceramic, resulting in high reliability. Traditional active solders are AgCuTi alloy solders, but silver-copper-titanium alloy solders have significant drawbacks. On the one hand, the melting process of silver-copper-titanium ternary alloys is complex and uncontrollable. Ti has the highest melting point and very low solubility in Ag or Cu, mainly forming various intermetallic compounds. These compounds are prone to aggregation and segregation. On the other hand, Ti is easily oxidized, leading to reduced activity during brazing and affecting welding performance. Moreover, to ensure a relatively low welding temperature, the Ag content in silver-copper-titanium ternary alloy solders is generally between 50% and 90% by weight, making the cost of this alloy system solder high. Summary of the Invention

[0003] The purpose of this disclosure is to provide an active solder paste composition for copper-clad ceramics, a method for copper-clad ceramics, and copper-clad ceramics. The active solder paste composition can not only reduce the silver content and the soldering temperature, but also increase the bonding strength between Ti and Cu, increase the soldering strength, and make the material less prone to segregation.

[0004] To achieve the above objectives, the first aspect of this disclosure provides an active solder paste composition for ceramic copper cladding, wherein, based on the total weight of the active solder paste composition, the active solder paste composition contains 1 to 20% by weight of a first metal powder, 75 to 94% by weight of a second metal powder, and the balance being flux; wherein the first metal powder contains titanium hydride, and the second metal powder contains a copper-phosphorus-silver alloy.

[0005] Optionally, based on the total weight of the second metal powder, the copper content is 80-90% by weight, preferably 85-90% by weight; the phosphorus content is 4-10% by weight, preferably 6-8% by weight; and the silver content is 3-10% by weight, preferably 4-6% by weight.

[0006] Optionally, the titanium content is 90% by weight or more, preferably 93% to 96% by weight, based on the total weight of the first metal powder.

[0007] Optionally, based on the total weight of the first metal powder and the second metal powder, the content of the first metal powder is 1 to 20% by weight, and the content of the second metal powder is 80 to 99% by weight.

[0008] Optionally, based on the total weight of the active solder paste composition, the total weight of the first metal powder and the second metal powder is 75-95% by weight.

[0009] Optionally, the absolute particle size of the first metal powder is less than 30 μm, and the median particle size D50 is 1 to 6 μm; the absolute particle size of the second metal powder is less than 80 μm, and the median particle size D50 is 10 to 30 μm.

[0010] Optionally, the flux contains a solvent, a dispersant, a binder, and an anti-settling agent; the solvent is selected from one or more of dibutyl phthalate, terpineol, butyl carbitol acetate, tributyl citrate, and lecithin; the dispersant is selected from one or more of stearic acid, polyacrylamide, and polyethylene glycol; the binder is selected from one or more of ethyl cellulose, polyvinyl butyral, and polyvinyl alcohol; and the anti-settling agent is selected from one or more of hydrogenated castor oil, polyamide wax, polyethylene glycol ether, and fatty amine polyoxyethylene ether.

[0011] Optionally, based on the total weight of the flux, the solvent content is 60-90% by weight, the dispersant content is 0.5-10% by weight, the binder content is 1-20% by weight, and the anti-settling agent content is 0.5-10% by weight.

[0012] The second aspect of this disclosure provides a method for ceramic copper plating, the method comprising: S1, coating an active solder paste composition provided in the first aspect of this disclosure onto the surface of a ceramic substrate and drying it to obtain a ceramic substrate with the active solder paste composition on its surface; S2, bringing the copper material to be soldered into contact with the ceramic substrate and performing heat soldering.

[0013] Optionally, the areal density of the active solder paste composition on the ceramic substrate coated with the active solder paste composition is 35–500 g / m³. 2 .

[0014] Optionally, the heating and welding are performed using a programmed temperature rise method. The programmed temperature rise conditions include: raising the temperature to a first target temperature of 300–400°C under a vacuum of 0.01–0.1 Pa and a heating rate of 10–15°C / min; then raising the temperature to a second target temperature of 500–600°C under a vacuum of 0.001–0.009 Pa and a heating rate of 5–10°C / min, and holding at that temperature for 15–60 min; then raising the temperature to a third target temperature of 800–950°C under a vacuum of 0.01–0.05 Pa and a heating rate of 3–6°C / min, and holding at that temperature for 10–60 min; and then cooling the temperature to a fourth target temperature of 550–700°C under a vacuum of 0.001–0.05 Pa and a cooling rate of 1–5°C / min, followed by natural cooling.

[0015] Optionally, the ceramic substrate is selected from silicon nitride ceramic, alumina ceramic or aluminum nitride ceramic; the thickness of the ceramic substrate is 0.2 to 1 mm, and the thickness of the copper material to be soldered is 0.2 to 1 mm, preferably 0.25 to 0.65 mm.

[0016] The third aspect of this disclosure provides a copper-clad ceramic prepared using the method described in the second aspect of this disclosure.

[0017] Through the above technical solution, this disclosure provides an active solder paste composition for copper-clad ceramics, a method for copper-clad ceramics, and copper-clad ceramics. The active solder paste composition includes a first metal powder and a second metal powder. The first metal powder contains titanium hydride, and the second metal powder contains a copper-phosphorus-silver alloy. TiH2 has high chemical stability, does not react with air or water, and begins to decompose and release hydrogen when heated to 400℃. The generated H2 can reduce the oxide layer on the surface of the copper-phosphorus alloy powder and also provides fresh active element Ti for welding, promoting the wetting of the solder and ceramic and reducing welding defects. Adding a small amount of low-melting-point phosphorus to the copper-phosphorus alloy powder not only reduces the silver content and solder cost but also lowers the welding temperature, keeping its liquidus temperature between 650 and 850℃. Simultaneously, it increases the bonding strength between Ti and Cu, increasing welding strength and making the material less prone to segregation.

[0018] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 This is an ultrasonic scan of the copper-clad ceramic plate 1 prepared in Embodiment 1 of this disclosure.

[0021] Figure 2 This is an ultrasonic scan of the comparative copper-clad ceramic plate 1 prepared in Comparative Example 1 of this disclosure. Detailed Implementation

[0022] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0023] The first aspect of this disclosure provides an active solder paste composition for copper-clad ceramics, wherein, based on the total weight of the active solder paste composition, the active solder paste composition contains 1 to 20% by weight of a first metal powder, 75 to 94% by weight of a second metal powder, and the balance being flux; wherein the first metal powder contains titanium hydride, and the second metal powder contains a copper-phosphorus-silver alloy.

[0024] The active solder paste composition disclosed herein for copper-clad ceramics contains a first metal powder and a second metal powder, wherein the first metal powder contains titanium hydride and the second metal powder contains a copper-phosphorus-silver alloy. This active solder paste composition has a low cost, and the titanium hydride and copper-phosphorus-silver alloy have a synergistic effect, effectively increasing the soldering strength and resulting in a smoother and denser solder surface. Specifically, the TiH2 in the active solder paste composition of this application has high chemical stability and does not react with air or water. It begins to decompose and release hydrogen at 400°C. The generated H2 can reduce the oxide layer on the surface of the copper-phosphorus-silver alloy and also provides fresh active element Ti for soldering, promoting the wetting of the solder and ceramic, thereby reducing soldering defects and making the solder surface smoother and denser. The phosphorus element contained in the copper-phosphorus-silver alloy not only reduces the silver content in the solder, lowering the solder cost, but also has a low melting point, which helps to lower the alloy's melting point, keeping its liquidus temperature between 650 and 850°C, thereby lowering the soldering temperature. In addition, phosphorus increases the bonding strength between Ti and Cu, increasing the soldering strength and making the material less prone to segregation.

[0025] In one specific embodiment of this disclosure, the first metal powder is titanium hydride, and the second metal powder is a copper-phosphorus-silver alloy.

[0026] In one embodiment of this disclosure, based on the total weight of the second metal powder, the copper content is 80-90% by weight, preferably 85-90% by weight; the phosphorus content is 4-10% by weight, preferably 6-8% by weight; and the silver content is 3-10% by weight, preferably 4-6% by weight. In the above embodiment, the copper-phosphorus-silver alloy of this disclosure contains an appropriate amount of low-melting-point phosphorus. Phosphorus not only reduces the silver content in the copper-silver alloy, reducing solder costs, but also ensures that the copper-phosphorus-silver alloy has a suitable liquidus line, thereby maintaining a relatively low welding temperature. Furthermore, it ensures the reactive bonding of Ti and Cu, making the material less prone to segregation and increasing welding strength. At the same time, the oxygen content in the second metal powder is low, which can prevent Cu from being oxidized.

[0027] In one embodiment of this disclosure, the titanium content is 90% by weight or more, preferably 93-96% by weight, based on the total weight of the first metal powder. In the above embodiment, by selecting a first metal powder with a high titanium content, the activity of the active solder paste composition can be improved, which is beneficial to promoting the wetting of the solder and ceramic, thereby reducing soldering defects.

[0028] In one embodiment of this disclosure, based on the total weight of the first metal powder and the second metal powder, the content of the first metal powder is 1-20% by weight, and the content of the second metal powder is 80-99% by weight. In the above embodiment, by selecting the preferred ratio of the first metal powder and the second metal powder, it is beneficial to enhance their synergistic effect, so as to further improve the welding strength and the smoothness and density of the weld surface.

[0029] In one embodiment of this disclosure, based on the total weight of the active solder paste composition, the total weight of the first metal powder and the second metal powder is 75-95% by weight, preferably 80-90% by weight. In the above embodiment, the content of the first metal powder and the second metal powder in the active solder paste composition is more suitable, which is beneficial to fully exert the soldering activity of the active solder paste composition, and to facilitate sufficient contact between the metal powder and the flux, thereby improving the dispersibility and solubility of the metal powder, and further improving the welding strength and the smoothness and density of the weld surface.

[0030] In one embodiment of this disclosure, the absolute particle size of the first metal powder is less than 30 μm, and the median particle size D50 is 1–6 μm, preferably 1–3 μm; the absolute particle size of the second metal powder is less than 80 μm, and the median particle size D50 is 10–30 μm, preferably 10–25 μm. Here, the absolute particle size refers to the actual particle size of the powder particles, obtained using a PSA-laser particle size analyzer; the median particle size D50 refers to the particle size corresponding to a cumulative particle size distribution percentage of 50%, which can be detected using laser diffraction. In the above embodiment, by selecting the first and second metal powders with preferred particle sizes, the problem of unmelted or precipitated particles due to large metal powder particles during welding can be avoided. Simultaneously, the oxidation degree of the active metal powder can be reduced, avoiding excessive oxidation, thereby contributing to further improvement in welding strength and the smoothness and density of the weld surface.

[0031] According to this disclosure, the solvents, dispersants, binders, and anti-settling agents contained in the flux can be those conventionally used by those skilled in the art. In one embodiment of this disclosure, the solvent contained in the flux is selected from one or more of dibutyl phthalate, terpineol, butyl carbitol acetate, tributyl citrate, and lecithin; the dispersant is selected from one or more of stearic acid, polyacrylamide, and polyethylene glycol; the binder is selected from one or more of ethyl cellulose, polyvinyl butyral (PVB), and polyvinyl alcohol; and the anti-settling agent is selected from one or more of hydrogenated castor oil, polyamide wax, polyethylene glycol ether, and fatty amine polyoxyethylene ether.

[0032] In one embodiment of this disclosure, based on the total weight of the flux, the solvent content is 60-90% by weight, preferably 70-90% by weight; the dispersant content is 0.5-10% by weight, preferably 1-3% by weight; the binder content is 1-20% by weight, preferably 5-15% by weight; and the anti-settling agent content is 0.5-10% by weight, preferably 1-5% by weight. In the above embodiment, by selecting a flux with the preferred composition, the solubility of the metal powder can be further improved, thereby facilitating further improvement in welding strength and the smoothness and density of the weld surface.

[0033] The second aspect of this disclosure provides a method for copper-clad ceramics, the method comprising: S1, coating an active solder paste composition provided in the first aspect of this disclosure onto the surface of a ceramic substrate and drying it to obtain a ceramic substrate with the active solder paste composition on its surface; S2, bringing a copper material to be soldered into contact with the ceramic substrate and performing heat soldering. The method of this disclosure can prepare copper-clad ceramics with high solder strength and excellent flatness and density of the soldered surface.

[0034] In a preferred embodiment, the method includes: S1, uniformly coating the upper and lower surfaces of a ceramic substrate with an active solder paste composition by screen printing and drying it to obtain a ceramic substrate with the active solder paste composition on its surface; S2, coating the upper and lower surfaces of the ceramic substrate with the copper material to be soldered and placing it in a vacuum welding furnace for heating and soldering.

[0035] According to this disclosure, there are no specific limitations on the drying conditions, as long as the metal in the active solder paste composition can be uniformly adhered to the surface of the ceramic substrate without falling off. In one specific embodiment, the drying conditions include: a temperature of 50–100°C and a time of 10–60 minutes.

[0036] In one embodiment of this disclosure, the areal density of the active solder paste composition on the ceramic substrate coated with the active solder paste composition is 35–500 g / m³. 2 Preferably 200–500 g / m 2 The areal density refers to the mass of the active solder paste composition contained per unit area of ​​the ceramic substrate. In the above embodiments, by selecting an active solder paste composition with a preferred areal density, the ceramic and the copper material to be soldered can be tightly bonded together, and it has good printability and increased soldering stability.

[0037] According to this disclosure, the methods of heating and welding are well known to those skilled in the art. In a preferred embodiment of this disclosure, the heating and welding are performed using a programmed temperature rise method; the programmed temperature rise conditions include: heating to a first target temperature of 300-400°C under a vacuum of 0.01-0.1 Pa and a heating rate of 10-15°C / min; then heating to a second target temperature of 500-600°C under a vacuum of 0.001-0.009 Pa and a heating rate of 5-10°C / min, and holding at that temperature for 15-60 min; then heating to a third target temperature of 800-950°C under a vacuum of 0.01-0.05 Pa and a heating rate of 3-6°C / min, and holding at that temperature for 10-60 min; then cooling to a fourth target temperature of 550-700°C under a vacuum of 0.001-0.05 Pa and a cooling rate of 1-5°C / min, followed by natural cooling. In the above embodiments, by selecting a preferred heating program, copper-clad ceramics with better welding strength and smooth and dense welding surface can be prepared.

[0038] This disclosure does not impose specific limitations on the materials of the ceramic substrate, as these are well known to those skilled in the art. In one embodiment of this disclosure, the ceramic substrate is selected from silicon nitride ceramics, alumina ceramics, or aluminum nitride ceramics, preferably silicon nitride ceramics; the thickness of the ceramic substrate can vary within a wide range, preferably 0.2–1 mm. The copper material to be soldered in this disclosure can be, for example, copper sheet or copper foil, and the thickness of the copper material to be soldered can also vary within a wide range, preferably 0.2–1 mm, more preferably 0.25–0.65 mm. In the above embodiments, by selecting a ceramic substrate and copper material of suitable thickness, it is beneficial to prepare copper-clad ceramics with superior welding strength and improved flatness and density of the weld surface. These copper-clad ceramics exhibit good electrical and thermal conductivity, and superior airtightness.

[0039] The third aspect of this disclosure provides a copper-clad ceramic prepared using the method described in the second aspect of this disclosure. The copper-clad ceramic provided by this disclosure exhibits high peel strength, dense welds, and is free of voids, demonstrating excellent performance.

[0040] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0041] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available products.

[0042] The particle size was measured using laser diffraction, and the instrument used was a PSA-laser particle size analyzer.

[0043] Example 1

[0044] (1) Based on the total weight of the active solder paste composition, the active solder paste composition contains 5% by weight of a first metal powder, 80% by weight of a second metal powder and 15% by weight of flux; the first metal powder is TiH2 (absolute particle size less than 30 μm, D50 of 3 μm), and the second metal powder is copper-phosphorus-silver alloy powder (absolute particle size less than 80 μm, D50 of 30 μm);

[0045] Based on the total weight of the copper-phosphorus-silver alloy powder, the copper content is 88% by weight, the phosphorus content is 7% by weight, and the silver content is 5% by weight. The flux includes terpineol, stearic acid, ethyl cellulose, and hydrogenated castor oil. Based on the total weight of the flux, the terpineol content is 90% by weight, the stearic acid content is 2% by weight, the ethyl cellulose content is 5% by weight, and the hydrogenated castor oil content is 3% by weight.

[0046] (2) Using silicon nitride ceramic with a thickness of 0.32 mm as the ceramic substrate, an active solder paste composition is printed on its upper and lower surfaces by screen printing. The screen size is 300 mesh, and the areal density of the printed active solder paste composition is 200 g / m². 2 The printed material is dried at 80℃ for 20 minutes to obtain a ceramic sheet; copper sheets are placed on the top and bottom of the dried ceramic sheet respectively, and after assembly, it is sent into a vacuum brazing furnace for heating and welding. The thickness of the copper sheet is 0.3mm.

[0047] (3) After loading the furnace, a vacuum is drawn, and the heating and welding are carried out using a programmed temperature rise method. The programmed temperature rise conditions include: heating to the first target temperature of 400℃ under the condition that the vacuum degree is lower than 0.1Pa and the heating rate is 10℃ / min; then heating to the second target temperature of 600℃ under the condition that the vacuum degree is 0.009Pa and the heating rate is 5℃ / min, and holding at that temperature for 30min; then heating to the third target temperature of 850℃ under the condition that the vacuum degree is 0.05Pa and the heating rate is 3℃ / min, and holding at that temperature for 30min; then cooling to the fourth target temperature of 600℃ under the condition that the vacuum degree is 0.05Pa and the cooling rate is 3℃ / min, and then cooling down with the furnace to obtain the copper-clad ceramic plate 1. The copper-clad ceramic plate 1 after exiting the furnace is ultrasonically scanned. Since the copper-clad ceramic plate 1 has a dense weld and no voids, the ultrasonic scan image shows a black background, such as Figure 1 As shown.

[0048] Example 2

[0049] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that, based on the total weight of the active solder paste composition, the active solder paste composition used contained 4% by weight of TiH2, 82% by weight of copper-phosphorus-silver alloy powder, and 14% by weight of flux, resulting in copper-clad ceramic plate 2.

[0050] Example 3

[0051] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that, based on the total weight of the active solder paste composition, the active solder paste composition used contained 3% by weight TiH2, 84% by weight copper-phosphorus-silver alloy powder and 13% by weight flux, resulting in copper-clad ceramic plate 3.

[0052] Example 4

[0053] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that the ceramic substrate was alumina ceramic, resulting in copper-clad ceramic plate 4.

[0054] Example 5

[0055] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that the D50 of the second metal powder was 20 μm, resulting in copper-clad ceramic plate 5.

[0056] Example 6

[0057] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that the D50 of the second metal powder was 40 μm, resulting in copper-clad ceramic plate 6.

[0058] Example 7

[0059] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that the D50 of the first metal powder was 10 μm, resulting in copper-clad ceramic plate 7.

[0060] Example 8

[0061] The copper-clad ceramic plate was prepared using the method of Example 1, except that: based on the total weight of the active solder paste composition, the active solder paste composition used contained 3% by weight of the first metal powder, 94% by weight of the second metal powder and 3% by weight of the flux, resulting in copper-clad ceramic plate 8.

[0062] Example 9

[0063] The copper-clad ceramic plate was prepared using the method of Example 1, except that: based on the total weight of the active solder paste composition, the active solder paste composition used contained 20% by weight of the first metal powder, 75% by weight of the second metal powder and 5% by weight of the flux, resulting in copper-clad ceramic plate 9.

[0064] Example 10

[0065] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that, based on the total weight of TiH2, the titanium content was 80% by weight, resulting in copper-clad ceramic plate 10.

[0066] Comparative Example 1

[0067] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that the active solder paste used was a commercially available silver-copper-titanium ternary alloy solder paste (titanium content 4% by weight), product model AgCuTi5, resulting in the comparative copper-clad ceramic plate 1. Ultrasonic scanning of the comparative copper-clad ceramic plate 1 revealed suspected unmelted or precipitated particles, and its back surface was not pure black. Figure 2 As shown.

[0068] Comparative Example 2

[0069] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that, based on the total weight of the active solder paste composition, the active solder paste composition used contained 15% by weight of TiH2, 70% by weight of copper-phosphorus-silver alloy powder, and 15% by weight of flux, resulting in the comparative copper-clad ceramic plate 2.

[0070] Comparative Example 3

[0071] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that, based on the total weight of the active solder paste composition, the active solder paste composition used contained 0.5% by weight of TiH2, 96% by weight of copper-phosphorus-silver alloy powder, and 3.5% by weight of flux, resulting in the comparative copper-clad ceramic plate 3.

[0072] Comparative Example 4

[0073] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that the first metal powder was pure titanium powder, resulting in the comparative copper-clad ceramic plate 4.

[0074] Comparative Example 5

[0075] The copper-clad ceramic plate was prepared using the method of Example 1, with the only difference being that the second metal powder was copper-silver alloy powder. Based on the total weight of the copper-silver alloy powder, the copper content was 95% by weight and the silver content was 5% by weight, resulting in the comparative copper-clad ceramic plate 5.

[0076] Test case

[0077] The copper-clad ceramic substrates obtained in the examples and comparative examples were subjected to peel strength tests and ultrasonic scanning. The peel strength test was conducted using a universal testing machine with QCTech-A3 software, a peel speed of 50 mm / min, and a peel stroke greater than 25 mm. The ultrasonic scanning test method was C-scan, and the testing instrument was an ultrasonic scanning microscope. The test results are shown in Table 1.

[0078] Table 1

[0079] Peel strength, N / mm Ultrasonic scanning test Example 1 >15 The weld is dense and free of voids. Example 2 >15 The weld is dense and free of voids. Example 3 >15 The weld is dense and free of voids. Example 4 >20, Internal peeling of ceramic The weld is dense and free of voids. Example 5 >20 The weld is dense and free of voids. Example 6 10～15 The weld is dense and free of voids. Example 7 10～15 The weld is dense and free of voids. Example 8 10～15 The weld is dense and free of voids. Example 9 >15 The weld is dense and free of voids. Example 10 10～15 The weld is dense and free of voids. Comparative Example 1 5～12 There are suspected unmelted or precipitated particles. Comparative Example 2 <5 There are suspected unmelted or precipitated particles. Comparative Example 3 <3 Large voids in the weld Comparative Example 4 9～13 There are a few small cavities. Comparative Example 5 - The copper foil and ceramic were not soldered together.

[0080] The data above shows that Examples 1-10, using the active solder paste composition of this disclosure, resulted in copper-clad ceramic plates with dense welds, no voids, and high peel strength. Comparative Examples 1-5, which did not use the method of this disclosure, produced comparative copper-clad ceramic plates with suspected unmelted or precipitated metal particles, voids, and weak peel strength, rendering them unusable. Therefore, the active solder paste compositions provided in Examples 1-10 of this disclosure are superior to those in Comparative Examples 1-5.

[0081] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0082] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0083] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An active solder paste composition for ceramic-coated copper, characterized by, Based on the total weight of the active solder paste composition, the active solder paste composition contains 1-20% by weight of a first metal powder, 75-94% by weight of a second metal powder, and the balance being flux; The first metal powder contains titanium hydride, and the second metal powder contains a copper-phosphorus-silver alloy; the median particle size D50 of the first metal powder is 1~6μm, and the median particle size D50 of the second metal powder is 20~30μm. Based on the total weight of the second metal powder, the copper content is 80-90% by weight, the phosphorus content is 4-10% by weight, and the silver content is 3-10% by weight.

2. The active solder paste composition according to claim 1, characterized in that, Based on the total weight of the second metal powder, the copper content is 85-90% by weight, the phosphorus content is 6-8% by weight, and the silver content is 4-6% by weight.

3. The active solder paste composition of claim 1, wherein, Based on the total weight of the first metal powder, the titanium content is 90% by weight or more.

4. The active solder paste composition of claim 3, wherein, Based on the total weight of the first metal powder, the titanium content is 93-96% by weight.

5. The active solder paste composition according to claim 1, characterized in that, Based on the total weight of the first metal powder and the second metal powder, the content of the first metal powder is 1 to 20% by weight, and the content of the second metal powder is 80 to 99% by weight.

6. The active solder paste composition of claim 1, wherein, Based on the total weight of the active solder paste composition, the total weight of the first metal powder and the second metal powder is 75-95% by weight.

7. The active solder paste composition of claim 1, wherein, The absolute particle size of the first metal powder is less than 30 μm, and the absolute particle size of the second metal powder is less than 80 μm.

8. The active solder paste composition according to claim 1, characterized in that, The flux contains solvents, dispersants, binders, and anti-settling agents; The solvent is selected from one or more of dibutyl phthalate, terpineol, butyl carbitol acetate, tributyl citrate, and lecithin; the dispersant is selected from one or more of stearic acid, polyacrylamide, and polyethylene glycol; the binder is selected from one or more of ethyl cellulose, polyvinyl butyral, and polyvinyl alcohol; and the anti-settling agent is selected from one or more of hydrogenated castor oil, polyamide wax, polyglycol ether, and fatty amine polyoxyethylene ether.

9. The active solder paste composition according to claim 8, characterized in that, Based on the total weight of the flux, the solvent content is 60-90% by weight, the dispersant content is 0.5-10% by weight, the binder content is 1-20% by weight, and the anti-settling agent content is 0.5-10% by weight.

10. A method for ceramic copper plating, characterized in that, The method includes: S1. The active solder paste composition according to any one of claims 1 to 9 is coated on the surface of a ceramic substrate and dried to obtain a ceramic substrate with the active solder paste composition on its surface. S2. Bring the copper material to be welded into contact with the ceramic substrate and heat it for welding.

11. The method according to claim 10, characterized in that, The surface density of the active solder paste composition on the ceramic substrate coated with the active solder paste composition is 35 to 500 g / m 2 .

12. The method of claim 10, wherein, The heating and welding are performed using a programmed temperature rise method; the conditions for the programmed temperature rise include: Under conditions of vacuum of 0.01~0.1 Pa and heating rate of 10~15℃ / min, the temperature is raised to the first target temperature of 300~400℃; Then, under a vacuum of 0.001~0.009 Pa and a heating rate of 5~10℃ / min, the temperature is raised to the second target temperature of 500~600℃ and held for 15~60 min. Then, under a vacuum of 0.01~0.05Pa and a heating rate of 3~6℃ / min, the temperature is raised to the third target temperature of 800~950℃ and held for 10~60min. Then, under conditions of vacuum of 0.001~0.05Pa and cooling rate of 1~5℃ / min, the temperature is reduced to the fourth target temperature of 550~700℃ and then allowed to cool naturally.

13. The method of claim 10, wherein, The ceramic substrate is selected from silicon nitride ceramics, alumina ceramics, or aluminum nitride ceramics; The thickness of the ceramic substrate is 0.2~1mm, and the thickness of the copper material to be soldered is 0.2~1mm.

14. The method according to claim 13, characterized in that, The thickness of the copper material to be soldered is 0.25~0.65mm.

15. Copper-clad ceramics prepared by any one of claims 10 to 14.

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