A conductive paste for metallization of electronic ceramics

Abstract

This invention discloses a conductive paste for metallization of electronic ceramics, belonging to the field of electronic materials technology. The conductive paste for metallization of electronic ceramics of this invention includes copper alloy powder, glass powder, and an organic carrier. By controlling the ratio of copper, aluminum, and zinc in the copper alloy, the thermal expansion coefficient of the alloy is adjusted, making it compatible with electronic ceramic substrates such as alumina ceramics and zinc oxide varistors, achieving metallization through sintering under air conditions. The addition of tin improves the solderability of the metallized layer, meeting the process requirements of electronic components. The glass powder added in this invention has a low initial melting temperature, high bonding strength with the copper alloy, and strong adhesion to the ceramic substrate; combined with a specific ratio of organic carrier, it effectively improves the conductivity of the metallized layer after sintering.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, and in particular relates to a conductive paste for metallizing electronic ceramics. Background Technology

[0002] The metallization materials used for electrodes in electronic components are generally silver or silver-copper alloy powder, or silver-coated copper powder. In recent years, to reduce the use of silver, pastes that largely replace silver have emerged, or pastes made with copper, silver, titanium, or other materials instead of silver powder. These are widely used in industries such as resistive ceramic components, solar cells, and printed circuit boards. However, due to the easy oxidation of copper, it requires reduction and calcination under reducing atmospheres such as hydrogen or nitrogen. This process involves large equipment, complex technology, and significant control challenges. Summary of the Invention

[0003] To address the technical problems in existing technologies, this invention provides a conductive paste for metallizing electronic ceramics. This invention uses a specific proportion of copper, aluminum, zinc, and tin alloy powders, adds silver-containing low-temperature glass powder, and uses a slightly reducing organic carrier to prepare the paste. It is suitable for screen printing to prepare internal electrodes for electronic ceramic components, and can be infiltrated under air conditions, completely eliminating the need for the precious metal silver and removing the complex equipment requirements of reducing atmospheres such as hydrogen or nitrogen.

[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a conductive paste for metallization of electronic ceramics, comprising the following components: copper alloy powder, glass powder, and organic carrier.

[0005] Furthermore, the slurry comprises, by mass percentage, 60-85% copper alloy powder, 1.5-8% glass powder, and 10-35% organic carrier.

[0006] Furthermore, by mass fraction, the copper alloy powder is composed of 85-95% copper, 2-7% aluminum, 2-8% zinc, and 0.4-1.5% tin; the fineness of the copper alloy powder is 0.2-0.8 μm.

[0007] This copper alloy powder is manufactured using an alloy smelting process. It exhibits good physical bonding with most electronic ceramic materials, such as alumina ceramics, zinc oxide ceramics, and barium carbonate ceramics, meeting the product's requirements for electrical properties and bonding strength. This copper alloy powder material retains its metallic properties even when heated to 300℃-850℃ in air, without significant oxidation, discoloration, or separation.

[0008] Further, by mass fraction, the glass powder comprises the following components: 30-40% B2O3, 40-50% Bi2O3, 10-20% ZnO, 1.5-4.5% SiO2, 1-3% Al2O3, 1-3% SnO2, 0.2-2% Na2O, 0.2-2.5% AgO, and 0.5-1.5% BaO.

[0009] Furthermore, the glass powder manufacturing process is as follows: using the above-mentioned raw materials, the glass powder is obtained by high-temperature melting, quenching, crushing, and sieving.

[0010] Furthermore, the initial melting temperature of the glass powder is 450°C.

[0011] Further, by mass fraction, the organic carrier comprises the following components: 10-20% resin, 70-80% solvent, 1-8% defoamer, 0.5-3% diluent, 1-1.5% active dispersant, 0.5-5% leveling agent, 0.5-5% thixotropic agent, 0.5-5% antioxidant, 0.5-5% stabilizer, and 0.2-2% wetting agent.

[0012] Furthermore, the resin is a modified epoxy resin; the solvent is at least one selected from tetrahydrofuran, diacetone alcohol, ethyl acetate, terpineol, diethylene glycol butyl ether acetate, and butyl carbitol.

[0013] Furthermore, the defoaming agent is an organosiloxane; the diluent is a tea polyphenol condensate; and the tea polyphenol condensate is a powder that has passed through an 180-mesh sieve.

[0014] Further, the active dispersant is tributyl phosphate; the leveling agent is fluorocarbon modified silane; the thixotropic agent is at least one of hydrogenated castor oil and fumed silica; the antioxidant is B900 composite antioxidant; the stabilizer is polyvinylpyrrolidone; and the wetting agent is a silane coupling agent.

[0015] Furthermore, the organic carrier preparation process is as follows: the above raw materials are fully dissolved and stirred evenly to obtain the organic carrier. This organic carrier uses MDI-modified epoxy resin, which has good wetting and bonding with copper. The addition of B900 antioxidant can play an anti-oxidation protection role for copper alloys during the sintering process, which is beneficial to improving the electrical conductivity of the slurry after sintering.

[0016] This invention provides a method for applying a conductive paste for metallizing electronic ceramics, characterized by the following steps: mixing copper alloy powder, glass powder and organic carrier to form a conductive paste, coating it onto the surface of an electronic ceramic material using screen printing or brushing, heating it to 450-850°C at a heating rate of 5-10°C / min in air, holding it at that temperature for 100-30 minutes and then allowing it to cool naturally to complete the metallization of the electronic ceramic material.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention adjusts the ratio of copper, aluminum, and zinc in a copper alloy to regulate the alloy's coefficient of thermal expansion, making it compatible with electronic ceramic substrates such as alumina ceramics and zinc oxide varistors. The addition of tin improves the solderability of the metallization layer, meeting the process requirements of electronic components.

[0018] The glass powder added in this invention has a low initial melting temperature, high bonding strength with copper alloys, and can firmly bond with ceramic substrates; when combined with a specific ratio of organic carrier, it effectively improves the density and conductivity of the metallized layer after the slurry is burned in.

[0019] The conductive paste of this invention can be directly infiltrated in air without the need for a reducing atmosphere, which simplifies the process equipment and reduces production costs; at the same time, it completely eliminates the use of precious metal silver, further controlling material costs. Attached Figure Description

[0020] Figure 1 The image shows the copper alloy material obtained in Example 1.

[0021] Figure 2 Image of the copper alloy powder prepared in Example 1.

[0022] Figure 3 The image shows the glass powder obtained in Example 1.

[0023] Figure 4 This is an image of the organic carrier prepared in Example 1.

[0024] Figure 5 The image shows the conductive paste prepared in Example 1. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] Example 1 This embodiment describes a method for preparing a conductive paste for metallization of electronic ceramics, which specifically includes the following steps: Step 1: Using granular or flake raw materials of copper, aluminum, zinc, and tin in a ratio of 85-95% copper, 2-7% aluminum, 2-8% zinc, and 0.4-1.5% tin, preferably electronic waste or industrial-grade metals, add them to a crucible according to the ratio, heat at 1200℃ for 5-10 minutes to melt, stir evenly, skim off the surface dross, and make a copper alloy material (such as...). Figure 1 The alloy material is then atomized into powder with a fineness of 0.2-0.8 μm, which is equivalent to 200-1500 mesh (e.g., ...). Figure 2 ).

[0027] Step 2: Using the materials and their mass fraction ratios shown in Table 1, the mixture is melted at 1700℃, quenched by dripping into water, dried, pulverized, and sieved to obtain glass powder (e.g. Figure 3 ).

[0028] Table 1: Composition and content of glass powder Step 3: Using the materials and their mass fraction ratios shown in Table 2, first dissolve the resin in an appropriate amount of solvent (heat to 55℃-65℃ in a water bath), then disperse and dissolve the dispersant, defoamer, etc., in an appropriate amount of solvent. Dilute the dissolved resin solution with a diluent and slowly add it to the dispersant solution while stirring. Add all components to the reactor and stir thoroughly until homogeneous. After homogeneity, the organic carrier (such as...) is obtained. Figure 4 ).

[0029] Table 2: Organic Carrier Components and Contents Step 4: Add 60-85% of the alloy powder from Step 1, 1.5-8% of the glass powder from Step 2, and 10-35% of the organic carrier from Step 3 to a reaction vessel, stir until homogeneous, and obtain a conductive paste for electronic ceramic metallization (e.g., Figure 5 ).

[0030] The metallization of electronic ceramic materials is achieved by screen printing coating onto the surface of the material and firing at temperatures of 450℃-850℃, resulting in a strong bond with the ceramic material, good electrical conductivity, and completion of the metallization process.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electroconductive paste for metalizing an electronic ceramic, characterized by comprising, as essential components, a glass frit, a metal oxide, and a solvent. The slurry comprises the following components: copper alloy powder, glass powder, and organic carrier.

2. The conductive paste for the metallization of electronic ceramics according to claim 1, characterized in that, The slurry comprises, by mass percentage, 60-85% of copper alloy powder, 1.5-8% of glass powder, and 10-35% of organic carrier.

3. The conductive paste for the metallization of electronic ceramics according to claim 2, characterized in that, The copper alloy powder consists of, by mass percentage, 85-95% of copper, 2-7% of aluminum, 2-8% of zinc, and 0.4-1.5% of tin; and has a fineness of 0.3-0.8 μm.

4. The conductive paste for the metallization of electronic ceramics according to claim 2, characterized in that, The glass powder comprises, by mass percentage, 30-40% of B2O3, 40-50% of Bi2O3, 10-20% of ZnO, 1.5-4.5% of SiO2, 1-3% of Al2O3, 1-3% of SnO2, 0.2-2% of Na2O, 0.2-2.5% of AgO, and 0.5-1.5% of BaO; and has a particle size of D50 of 0.5-20 μm, D90 of ≤5 μm, and an average mesh number of 2000 mesh; and has an initial melting temperature of 450℃.

5. The conductive paste for the metallization of electronic ceramics according to claim 2, characterized in that, The organic carrier consists of, by mass percentage, 10-20% of resin, 70-80% of solvent, 1-8% of defoaming agent, 0.5-3% of diluent, 1-1.5% of active dispersant, 0.5-5% of leveling agent, 0.5-5% of thixotropic agent, 0.5-5% of anti-oxidant, 0.5-5% of stabilizer, and 0.2-2% of wetting agent.

6. The conductive paste for the metallization of electronic ceramics according to claim 5, characterized in that, The resin is modified epoxy resin; the solvent is at least one of tetrahydrofuran, diacetone alcohol, ethyl acetate, terpineol, diethylene glycol butyl ether acetate, and butyl carbitol; the defoaming agent is organosiloxane; the diluent is tea polyphenol polycondensate; the tea polyphenol polycondensate is powder passing through a 180 mesh sieve; the active dispersant is tributyl phosphate; the leveling agent is fluorocarbon-modified silane; the thixotropic agent is at least one of hydrogenated castor oil and fumed silica; the anti-oxidant is B900 composite antioxidant; the stabilizer is polyvinylpyrrolidone; and the wetting agent is silane coupling agent.

7. The conductive paste for the metallization of electronic ceramics according to claim 5, characterized in that, The method comprises the following steps: mixing copper alloy powder, glass powder, and organic carrier to prepare conductive slurry; coating the slurry on the surface of electronic ceramic material by screen printing or brushing; heating to 450-850℃ at a heating rate of 5-10℃ / min in air; and naturally cooling after holding for 10-30 min to complete the metallization of the electronic ceramic material.

8. The conductive paste for the metallization of electronic ceramics according to claim 5, characterized in that, ​ 9. The method of claim 1-8, wherein the conductive paste for the metallization of electronic ceramics is applied by screen printing. ​

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