Silver-coated copper powder with low-temperature sintering activity as well as preparation method and application of silver-coated copper powder

Abstract

The invention relates to the field of metal powder material preparation, in particular to silver-coated copper powder with low-temperature sintering activity and a preparation method and application thereof.The preparation method comprises the following steps that copper powder, a reducing agent, a complexing agent composition and a silver plating solution are mixed and react, and the silver-coated copper powder is obtained; the complexing agent composition comprises at least two of ammonia water, triethylene tetramine, ethylenediamine, diethanol amine, benzimidazole, tartaric acid, nitrilotriacetic acid, ethylenediamine tetraacetic acid, disodium ethylene diamine tetraacetate, tetrasodium ethylene diamine tetraacetate and glycine. The preparation method disclosed by the invention is short in process flow, relatively low in cost, capable of keeping good batch stability and easy for industrial production; according to the obtained silver-coated copper powder, under the condition that the silver content is low, the completeness and compactness of a silver layer on the surface of the copper powder are good, the oxidation resistance is high, the service reliability of the silver-coated copper powder is improved, the production cost is saved, and the silver-coated copper powder further has good low-temperature sintering activity.

Description

Technical Field

[0001] The present application relates to the field of metal powder material preparation, and in particular to a silver-coated copper powder with low-temperature sintering activity, and a preparation method and application thereof. Background Art

[0002] Low-temperature process batteries such as N-type heterojunction cells, HBC cells, and crystalline silicon perovskite stacked cells are the future development direction of photovoltaic cell technology, but their high costs severely limit their development. Silver paste, as the largest non-silicon cost of photovoltaic cells, is the key to cost reduction. Silver-coated copper powder is an excellent composite metal conductive powder material with significant cost advantages over pure silver. It has excellent conductivity and stable chemical properties. At the same time, it can effectively overcome the electromigration of pure silver metal and the easy oxidation of copper. Therefore, it is an important technical path for metallization cost reduction.

[0003] Under the industry trend of reducing costs and increasing efficiency, the amount of silver coating on ultrafine silver-coated copper powder continues to decline, but at the same time, its coating quality is required to remain at a good level. At present, the domestic silver-coated copper powder with low silver content needs to be improved in terms of coating integrity and density, and has problems such as poor service reliability and batch stability, which seriously affects the application performance of downstream products. Furthermore, it is generally believed that the high conductivity of low-temperature silver-coated copper slurry is closely related to the sintering activity of submicron silver powder, while the sintering activity between submicron silver powder and micron silver-coated copper powder is ignored. The sintering between this micro-nano combined powder can further improve the electrical properties of the slurry.

[0004] Therefore, it is very important to provide a low silver content silver-coated copper powder with advantages in coating integrity and density as well as sintering activity. Summary of the invention

[0005] In view of the above problems, the present application provides a silver-coated copper powder with low-temperature sintering activity, a preparation method and an application thereof. The preparation method has a short process flow, low cost, can maintain good batch stability, and is easy to industrialize. The obtained silver-coated copper powder can have a low silver content, and the silver layer on the surface of the copper powder has good integrity and density, strong antioxidant ability, thereby improving the service reliability of the silver-coated copper powder, saving production costs, and having good low-temperature sintering activity.

[0006] In a first aspect, the present application provides a method for preparing silver-coated copper powder having low-temperature sintering activity, the preparation method comprising the following steps: mixing copper powder, a reducing agent, a complexing agent composition and a silver plating solution, reacting to obtain the silver-coated copper powder;

[0007] The complexing agent composition comprises at least two of ammonia water, triethylenetetramine, ethylenediamine, diethanolamine, benzimidazole, tartaric acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, and glycine.

[0008] In the technical solution of the implementation mode of the present application, silver-coated copper powder is prepared by a liquid phase chemical method using a simple one-step method, which has a short process flow, low cost, can maintain good batch stability, and is easy to industrialize.

[0009] The present application adopts a complexing agent composition to control the nucleation and coating reaction rates of silver atoms to a moderate level, thereby regulating the structure of the silver layer on the surface of the copper powder. When the silver content is low, the integrity and density of the silver layer on the surface of the copper powder are better, and the antioxidant ability is strong, thereby improving the service reliability of the silver-coated copper powder and saving production costs. In addition, the preparation method of the present application can regulate the morphology of the surface of the silver-coated copper powder, such as roughness and form, so that it has better low-temperature sintering activity.

[0010] As an example, the complexing agent composition includes, but is not limited to, a combination of aqueous ammonia, diethanolamine and ethylenediaminetetraacetic acid, a combination of diethanolamine, benzimidazole and ethylenediaminetetraacetic acid, a combination of aqueous ammonia, triethylenetetramine and glycine, a combination of triethylenetetramine, nitrilotriacetic acid and ethylenediaminetetraacetic acid, a combination of aqueous ammonia, triethylenetetramine and ethylenediaminetetraacetic acid, a combination of aqueous ammonia and glycine, and the like.

[0011] Illustratively, the molar ratio of aqueous ammonia, diethanolamine and ethylenediaminetetraacetic acid can be (0.1-5): (0.1-5): (0.1-5), preferably 1:2:1, wherein 0.1-5 can be 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, etc., and the added amount of each component can be the same or different.

[0012] The molar ratio of diethanolamine, benzimidazole and ethylenediaminetetraacetic acid can be (0.1-5): (0.1-5): (0.1-5), preferably 2:1:1, wherein 0.1-5 can be 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, etc., and the added amount of each component can be the same or different.

[0013] The molar ratio of ammonia water, triethylenetetramine and glycine can be (0.1-5): (0.1-5): (0.1-5), preferably 2:1:1, wherein 0.1-5 can be 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, etc., and the added amount of each component can be the same or different.

[0014] The molar ratio of triethylenetetramine, nitrilotriacetic acid and ethylenediaminetetraacetic acid can be (0.1-5): (0.1-5): (0.1-5), preferably 3:1:2, wherein 0.1-5 can be 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, etc., and the addition amount of each component can be the same or different.

[0015] The molar ratio of ammonia water, triethylenetetramine and ethylenediaminetetraacetic acid can be (0.1-5): (0.1-5): (0.1-5), preferably 2:1:2, wherein 0.1-5 can be 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, etc., and the addition amount of each component can be the same or different.

[0016] The molar ratio of ammonia water to glycine can be (0.1-5): (0.1-5), preferably 2:1, wherein 0.1-5 can be 0.5, 1, 2, 2.5, 3, 3.5, 4, 4.5, etc., and the added amount of each component can be the same or different.

[0017] Preferably, the mass ratio of the copper powder to the complexing agent composition is 100:(10-40), wherein 10-40 can be 15, 20, 25, 30, 35, etc.

[0018] Preferably, the copper powder has a shape of any one of sphere, quasi-sphere, flake or polyhedron.

[0019] Preferably, the copper powder has a Dv50 particle size of 1 to 8 μm, such as 2 μm, 4 μm, 6 μm, etc.

[0020] In this application, Dv50 particle size refers to the particle size at which 50% of the particle volume is smaller than this particle size in the volume distribution of particles. That is, Dv50 particle size is the median of the particle volume distribution, which means that among all particles, half of the particle volume is larger than Dv50 particle size, and the other half of the particle volume is smaller than Dv50 particle size.

[0021] Preferably, the copper powder is surface treated before mixing and then mixed with water to form a copper powder solution.

[0022] In the technical solution of the implementation mode of the present application, the main function of the surface treatment is to remove antioxidants and oxides on the surface of the copper powder and to activate the surface of the copper powder.

[0023] Preferably, the surface treatment method includes pickling with acid solution.

[0024] Preferably, the acid used in the acid solution includes any one of sulfuric acid, nitric acid or hydrochloric acid, or a combination of at least two of them.

[0025] Preferably, the mass concentration of the acid solution is 1% to 5%.

[0026] Exemplarily, the mass concentration of the acid solution is one of 1%, 2%, 3%, 4%, 5%, or any value satisfying the above range.

[0027] Preferably, the temperature of the water is 20-80°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C, etc.

[0028] Preferably, the mass ratio of the copper powder to water is 1:(2-20), wherein 2-20 can be 4, 6, 8, 10, 12, 14, 16, 18, etc.

[0029] Preferably, the reducing agent comprises any one of ascorbic acid, formaldehyde, glucose, potassium tartrate, hydrazine hydrate or potassium sodium tartrate, or a combination of at least two thereof.

[0030] Preferably, the reducing agent is mixed with the copper powder solution before the next step.

[0031] As an example, in the mixed solution of the reducing agent and the copper powder solution, the concentration of the reducing agent is 0.01 to 1 mol / L, that is, the concentration of the aqueous solution of the reducing agent is 0.01 to 1.00 mol / L.

[0032] Exemplarily, the concentration of the reducing agent is one of 0.01 mol / L, 0.02 mol / L, 0.05 mol / L, 0.08 mol / L, 0.10 mol / L, 0.20 mol / L, 0.30 mol / L, 0.40 mol / L, 0.50 mol / L, 0.60 mol / L, 0.70 mol / L, 0.80 mol / L, 0.90 mol / L, 1.00 mol / L or any value satisfying the above range.

[0033] Preferably, the concentration of the silver plating solution is 0.01-2 mol / L.

[0034] Exemplarily, the concentration of the silver plating solution is one of 0.01mol / L, 0.02mol / L, 0.05mol / L, 0.08mol / L, 0.10mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L, 0.5mol / L, 0.6mol / L, 0.7mol / L, 0.8mol / L, 0.9mol / L, 1.0mol / L, 1.1mol / L, 1.2mol / L, 1.3mol / L, 1.4mol / L, 1.5mol / L, 1.6mol / L, 1.7mol / L, 1.8mol / L, 1.9mol / L, 2.00mol / L or any value satisfying the above range.

[0035] In the present application, the concentration of the silver plating solution refers to the concentration of the silver plating substance in the solution. As an example, the silver plating substance in the silver plating solution includes silver salts, such as silver nitrate and silver acetate.

[0036] As an example, the molar ratio of the reducing agent to the silver salt is (2-30):1, wherein 2-30 can be 5, 10, 15, 20, 25, etc.

[0037] Preferably, the complexing agent composition is first mixed with the silver plating solution, and then mixed with the copper powder and the reducing agent.

[0038] Preferably, the reaction time is 20 to 120 min, such as 40 min, 60 min, 80 min, 100 min, etc.

[0039] Preferably, the reaction further includes washing, separation and drying.

[0040] Preferably, the solvent used in the washing comprises water.

[0041] Preferably, the separation method includes filter press separation.

[0042] Preferably, the drying temperature is 40-80°C (e.g., 50°C, 60°C, 70°C, etc.), and / or the drying time is 6-48h (e.g., 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, etc.).

[0043] As a preferred technical solution, the preparation method comprises the following steps:

[0044] (1) firstly pickling copper powder with a Dv50 particle size of 1 to 8 μm, and then mixing it with water at 20 to 80° C., wherein the mass ratio of the copper powder to the water is 1:(2 to 20), to form a copper powder solution;

[0045] Mixing the complexing agent composition with a silver plating solution having a concentration of 0.01 to 2 mol / L to form a silver plating solution containing the complexing agent composition;

[0046] (2) The copper powder solution is first mixed with a reducing agent, and then mixed with a silver plating solution containing a complexing agent composition, reacted for 20 to 120 minutes, and then washed, separated and dried to obtain the silver-coated copper powder.

[0047] As an example, the separation further includes an operation of adding a surface modifier, and then drying to obtain silver-coated copper powder containing a surfactant.

[0048] In a second aspect, the present application provides a silver-coated copper powder, which is obtained by the preparation method described in the first aspect.

[0049] Preferably, based on the total mass of the silver-coated copper powder as 100%, the mass content of silver is 5% to 20%, more preferably 5% to 15%, for example 6%, 8%, 10%, 12%, 14%, 16%, 18%, etc.

[0050] Preferably, the shape of the silver-coated copper powder includes a polyhedron.

[0051] In the technical solution of the implementation mode of the present application, the surface of the silver-coated copper powder of the present application has a certain roughness and crystal shape, which is beneficial to improving the low-temperature sintering activity of the silver-coated copper powder.

[0052] In a third aspect, the present application provides a silver-coated copper powder composition with low-temperature sintering activity. The silver-coated copper powder composition comprises a surface modifier and the silver-coated copper powder obtained by the preparation method described in the first aspect, or the silver-coated copper powder described in the second aspect.

[0053] Preferably, the mass ratio of the surface modifier to the silver-coated copper powder is (0.5-50):1000, wherein 0.5-50 can be 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, etc.

[0054] Exemplarily, the mass ratio of the surface modifier to the silver-coated copper powder is one of 0.5:1000, 1:1000, 2:1000, 3:1000, 4:1000, 5:1000, 6:1000, 7:1000, 8:1000, 9:1000, 10:1000, 20:1000, 30:1000, 40:1000, 50:1000 or any value satisfying the above range.

[0055] Preferably, the surface modifier includes one or more combinations of oleic acid, oleamide, lactic acid, oxalic acid, linolenic acid, malic acid, stearic acid, palmitic acid, lauric acid, polyaspartic acid, cysteine, glutamic acid, mercaptoalanine, formic acid, acetic acid, benzotriazole, methylbenzotriazole, sodium mercaptobenzothiazole, glycidyloxypropyltrimethylsilane, 3-glycidyloxypropylmethyldiethoxysilane, aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, and diethylenetriaminepropyltrimethoxysilane.

[0056] For example, a two-component surface modifier with a mass ratio of oleic acid to oleic acid amide of 1:1 is used. As a preferred technical solution, the preparation method of the silver-coated copper powder composition comprises the following steps:

[0057] (1) firstly pickling copper powder with a Dv50 particle size of 1 to 8 μm, and then mixing it with water at 20 to 80° C., wherein the mass ratio of the copper powder to the water is 1:(2 to 20), to form a copper powder solution;

[0058] Mixing the complexing agent composition with a silver plating solution having a concentration of 0.01 to 2 mol / L to form a silver plating solution containing the complexing agent composition;

[0059] (2) The copper powder solution is first mixed with a reducing agent, and then mixed with a silver plating solution containing a complexing agent composition, reacted for 20 to 120 minutes, and then washed, separated, added with a surface modifier, mixed and dried to obtain the silver-coated copper powder composition, i.e., silver-coated copper powder containing a surface modifier.

[0060] Preferably, the silver-coated copper powder composition further comprises submicron silver powder and a solvent.

[0061] As an example, the mass ratio of submicron silver powder, silver-coated copper powder and solvent can be (1-10): (1-10): 1, wherein 1-10 can be 2, 4, 6, 8, etc., and the added amounts of submicron silver powder and silver-coated copper powder can be the same or different.

[0062] Preferably, the solvent is diethylene glycol butyl ether acetate.

[0063] Preferably, the submicron silver powder has a particle size Dv50 of 100-300 nm, more preferably 200 nm, such as 150 nm, 200 nm, 250 nm, etc.

[0064] As an example, the preparation method of the silver-coated copper powder composition includes the following steps: directly mixing submicron silver powder, silver-coated copper powder, a surface modifier and a solvent.

[0065] As an example, the preparation method of the silver-coated copper powder composition includes the following steps: firstly mixing the silver-coated copper powder and the surface modifier, and then mixing with the submicron silver powder and the solvent. The above process can save the process flow and facilitate the direct use of the silver-coated copper powder.

[0066] As an example, the preparation method of the silver-coated copper powder composition includes the following steps: adding a surface modifier during the preparation of the silver-coated copper powder, and then mixing it with submicron silver powder and a solvent.

[0067] As an example, the separated silver-coated copper powder containing the solvent can be mixed with a surface modifier and then dried to obtain the silver-coated copper powder containing the surface modifier.

[0068] As a preferred technical solution, the preparation method of the silver-coated copper powder composition comprises the following steps:

[0069] (1) firstly pickling copper powder with a Dv50 particle size of 1 to 8 μm, and then mixing it with water at 20 to 80° C., wherein the mass ratio of the copper powder to the water is 1:(2 to 20), to form a copper powder solution;

[0070] Mixing the complexing agent composition with a silver plating solution having a concentration of 0.01 to 2 mol / L to form a silver plating solution containing the complexing agent composition;

[0071] (2) mixing the copper powder solution with a reducing agent, and then mixing it with a silver plating solution containing a complexing agent composition, reacting for 20 to 120 minutes, and then washing, separating, adding a surface modifier, mixing and drying to obtain the silver-coated copper powder composition, i.e., silver-coated copper powder containing a surface modifier;

[0072] (3) Mixing the silver-coated copper powder containing the surface modifier, the submicron silver powder and the solvent to obtain the silver-coated copper powder composition. Compared with the prior art, the technical solution of the present application has at least the following beneficial effects:

[0073] (1) The present application adopts a liquid phase chemical method and a simple one-step method to prepare silver-coated copper powder, which has a short process flow, low cost, can maintain good batch stability, and is easy to industrialize.

[0074] (2) The silver-coated copper powder obtained by the preparation method of the present application can make the integrity and density of the silver layer on the surface of the copper powder better when the silver content is low, and has strong antioxidant ability, thereby improving the service reliability of the silver-coated copper powder and saving production costs.

[0075] (3) The silver-coated copper powder obtained by the preparation method of the present application has good low-temperature sintering activity.

[0076] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0078] Figure 1 This is a SEM image of the silver-coated copper powder prepared in Example 1 provided in the present application;

[0079] Figure 2 This is a SEM image of the silver-coated copper powder prepared in Comparative Example 1 provided in the present application;

[0080] Figure 3 This is a SEM image of the silver-coated copper powder prepared in Comparative Example 2 provided in the present application;

[0081] Figure 4 This is a SEM image of the silver-coated copper powder composition formed by the silver-coated copper powder containing a surface modifier, submicron silver powder and a solvent prepared in Example 1 provided in the present application after low-temperature sintering. DETAILED DESCRIPTION

[0082] The following embodiments of the technical solution of the present application will be described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0083] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0084] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0085] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "2-10" means that all real numbers between "2-10" are listed in this document, and "2-10" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0086] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0087] Example 1

[0088] This embodiment provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0089] (1) Polyhedral ultrafine copper powder with a Dv50 particle size of 5 μm was selected as the raw material powder.

[0090] (2) 100 g of copper powder was placed in 500 mL of 2 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 500 mL of 60°C pure water to obtain a copper powder solution.

[0091] (3) Add 0.2 mol of reducing agent ascorbic acid and stir for 5 minutes.

[0092] (4) Prepare 0.2 mol / L silver nitrate solution according to the silver content.

[0093] (5) 30 g of a complexing agent composition of ammonia water, diethanolamine and ethylenediaminetetraacetic acid was added to the silver salt solution of step (4) in a molar ratio of 1:2:1, and mixed evenly to obtain a silver plating solution.

[0094] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 40 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0095] (7) A surface modifier is added to the silver-coated copper powder, specifically oleic acid and oleic acid amide in a mass ratio of 1:1 and a total mass of 1 g, to perform surface modification.

[0096] (8) The surface-modified silver-coated copper powder is vacuum dried at 60° C. for 12 h to obtain the silver-coated copper powder composition, i.e., the silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 8%); the silver-coated copper powder composition has low-temperature sintering activity.

[0097] Example 2

[0098] This embodiment provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0099] (1) Polyhedral ultrafine copper powder with a Dv50 particle size of 4 μm was selected as the raw material powder.

[0100] (2) 100 g of copper powder was placed in 500 mL of 3 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 500 mL of 60°C pure water to obtain a copper powder solution.

[0101] (3) Add a combined reducing agent with a molar ratio of ascorbic acid to glucose of 2:1 and stir for 5 minutes.

[0102] (4) Prepare 0.4 mol / L silver nitrate solution according to the silver content.

[0103] (5) 30 g of the complexing agent composition of diethanolamine, benzimidazole and ethylenediaminetetraacetic acid was added to the silver salt solution of step (4) at a molar ratio of 2:1:1, and mixed evenly to obtain a silver plating solution.

[0104] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 50 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0105] (7) A surface modifier, specifically 0.5 g of stearic acid, was added to the silver-coated copper powder for surface modification.

[0106] (8) The surface-modified silver-coated copper powder is vacuum dried at 60° C. for 12 h to obtain the silver-coated copper powder composition, i.e., the silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 12%); the silver-coated copper powder composition has low-temperature sintering activity.

[0107] Example 3

[0108] This embodiment provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0109] (1) Select spherical ultrafine copper powder with a Dv50 particle size of 3 μm as the raw material powder.

[0110] (2) 100 g of copper powder was placed in 500 mL of 3 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 500 mL of 60°C pure water to obtain a copper powder solution.

[0111] (3) Add a combined reducing agent having a molar ratio of ascorbic acid to potassium sodium tartrate of 1:1 and stir for 5 minutes.

[0112] (4) Prepare 0.2 mol / L silver nitrate solution according to the silver content.

[0113] (5) 30 g of a complexing agent composition of ammonia water, triethylenetetramine and glycine was added to the silver salt solution of step (4) at a molar ratio of 2:1:1, and mixed evenly to obtain a silver plating solution.

[0114] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 60 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0115] (7) A surface modifier, specifically 0.1 g of oleic acid amide, was added to the silver-coated copper powder for surface modification.

[0116] (8) The surface-modified silver-coated copper powder is vacuum dried at 60° C. for 12 h to obtain the silver-coated copper powder composition, i.e., the silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 15%); the silver-coated copper powder composition has low-temperature sintering activity.

[0117] Example 4

[0118] This embodiment provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0119] (1) Select spherical ultrafine copper powder with a Dv50 particle size of 2 μm as the raw material powder.

[0120] (2) 100 g of copper powder was placed in 1000 mL of 5 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 1000 mL of 60° C. pure water to obtain a copper powder solution.

[0121] (3) Add a combined reducing agent having a molar ratio of glucose to potassium sodium tartrate of 3:1 and stir for 5 minutes.

[0122] (4) Prepare 0.1 mol / L silver nitrate solution according to the silver content.

[0123] (5) 30 g of the complexing agent composition of triethylenetetramine, nitrilotriacetic acid and ethylenediaminetetraacetic acid was added to the silver salt solution of step (4) in a molar ratio of 3:1:2, and mixed evenly to obtain a silver plating solution.

[0124] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 60 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0125] (7) A surface modifier, specifically stearic acid and palmitic acid in a mass ratio of 2:1 and a total mass of 3 g, was added to the silver-coated copper powder for surface modification.

[0126] (8) The surface-modified silver-coated copper powder is vacuum dried at 60° C. for 12 h to obtain the silver-coated copper powder composition, i.e., the silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 15%); the silver-coated copper powder composition has low-temperature sintering activity.

[0127] Example 5

[0128] This embodiment provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0129] (1) Select spherical ultrafine copper powder with a Dv50 particle size of 5 μm as the raw material powder.

[0130] (2) 100 g of copper powder was placed in 1000 mL of 1 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 1000 mL of 60° C. pure water to obtain a copper powder solution.

[0131] (3) Add 0.2 mol of reducing agent ascorbic acid and stir for 5 minutes.

[0132] (4) Prepare 0.4 mol / L silver nitrate solution according to the silver content.

[0133] (5) 10 g of a complexing agent composition of ammonia water, triethylenetetramine and ethylenediaminetetraacetic acid was added to the silver salt solution of step (4) in a molar ratio of 2:1:2, and mixed evenly to obtain a silver plating solution.

[0134] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 30 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0135] (7) A surface modifier, specifically lactic acid and polyaspartic acid in a mass ratio of 1:1 and a total mass of 2 g, was added to the silver-coated copper powder for surface modification.

[0136] (8) The surface-modified silver-coated copper powder is vacuum dried at 60° C. for 24 h to obtain the silver-coated copper powder composition, i.e., the silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 5%); the silver-coated copper powder composition has low-temperature sintering activity.

[0137] Example 6

[0138] This embodiment provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0139] (1) Select flaky ultrafine copper powder with a Dv50 particle size of 5 μm as raw material powder.

[0140] (2) 100 g of copper powder was placed in 500 mL of 2 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 500 mL of 60°C pure water to obtain a copper powder solution.

[0141] (3) Add 0.4 mol of reducing agent hydrazine hydrate and stir for 5 minutes.

[0142] (4) Prepare 0.8 mol / L silver nitrate solution according to the silver content.

[0143] (5) 40 g of a complexing agent composition of ammonia water:glycine was added to the silver salt solution of step (4) at a molar ratio of 2:1, and the mixture was mixed to obtain a silver plating solution.

[0144] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 40 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0145] (7) A surface modifier, specifically 0.2 g of benzotriazole, was added to the silver-coated copper powder for surface modification.

[0146] (8) The surface-modified silver-coated copper powder is vacuum dried at 60° C. for 24 h to obtain the silver-coated copper powder composition, i.e., the silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 10%); the silver-coated copper powder composition has low-temperature sintering activity.

[0147] Comparative Example 1

[0148] This comparative example provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0149] (1) Polyhedral ultrafine copper powder with a Dv50 particle size of 5 μm was selected as the raw material powder.

[0150] (2) 100 g of copper powder was placed in 500 mL of 2 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 500 mL of 60°C pure water to obtain a copper powder solution.

[0151] (3) Add 0.2 mol of reducing agent ascorbic acid and stir for 5 minutes.

[0152] (4) Prepare 0.2 mol / L silver salt solution according to the silver content.

[0153] (5) Slowly add 30 g of complexing agent ammonia water into the silver salt solution of step (4) until it becomes clear and transparent to obtain a silver plating solution.

[0154] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 40 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0155] (7) A surface modifier is added to the silver-coated copper powder, specifically oleic acid and oleic acid amide in a mass ratio of 1:1 and a total mass of 1 g, to perform surface modification.

[0156] (8) The surface-modified silver-coated copper powder is vacuum-dried at 60° C. for 12 h to obtain the silver-coated copper powder composition, i.e., silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 8%).

[0157] This comparative example is the same as Example 1, except that only a single complexing agent, ammonia water, is added to this comparative example.

[0158] Comparative Example 2

[0159] This comparative example provides a method for preparing a silver-coated copper powder composition, the preparation method comprising the following steps:

[0160] (1) Select spherical ultrafine copper powder with a Dv50 particle size of 2 μm as the raw material powder.

[0161] (2) 100 g of copper powder was placed in 1000 mL of 5 wt% sulfuric acid solution, stirred for 10 min to remove surface antioxidants and oxides, washed with deionized water until neutral, and then the copper powder was placed in 1000 mL of 60° C. pure water to obtain a copper powder solution.

[0162] (3) Add a combined reducing agent having a molar ratio of glucose to potassium sodium tartrate of 3:1 and stir for 5 minutes.

[0163] (4) Prepare a 0.1 mol / L silver salt solution based on the silver content.

[0164] (5) Add 0.1 mol of triethylenetetramine to the silver salt solution of step (4), mix well to obtain a silver plating solution.

[0165] (6) Slowly add the silver plating solution to the copper powder reducing agent solution of step (3), react for 60 minutes, wash the silver-coated copper powder with deionized water until the pH is neutral and separate by filter pressing.

[0166] (7) A surface modifier, specifically stearic acid and palmitic acid in a mass ratio of 2:1 and a total mass of 3 g, was added to the silver-coated copper powder for surface modification.

[0167] (8) The surface-modified silver-coated copper powder is vacuum-dried at 60° C. for 12 h to obtain the silver-coated copper powder composition, i.e., silver-coated copper powder containing a surface modifier (wherein the mass content of silver in the silver-coated copper powder is 15%).

[0168] This comparative example is the same as Example 4, except that only a single complexing agent, triethylenetetramine, is added to this comparative example.

[0169] Performance Testing

[0170] (1) Morphology: The morphology of the silver-coated copper powder obtained by the preparation methods described in Example 1, Comparative Example 1 and Comparative Example 2 was observed using a scanning electron microscope (SEM). Figure 1 , Figure 2 and Figure 3 It can be seen that the silver-coated copper powder obtained by the preparation method described in the present application has a polyhedral shape, the surface silver layer has higher density and integrity, and has a certain degree of roughness.

[0171] (2) Low-temperature sintering activity: Submicron silver powder with a Dv50 particle size of 200 nm, the silver-coated copper powder containing a surface modifier prepared in Example 1, and a solvent (butyl acetate) were directly mixed in a mass ratio of 4:5:1 and sintered at 200°C for 8 minutes. Figure 4 As shown, the results show that submicron silver powder and micron silver-coated copper powder form an interlaced spatial network structure, i.e., a conductive channel, through atomic diffusion at a temperature below the melting point of the metal, which further improves the electrical properties of the slurry.

[0172] In summary, the present application adopts a liquid phase chemical method and a simple one-step method to prepare silver-coated copper powder, which has a short process flow, low cost, can maintain good batch stability, and is easy to industrialize; the silver-coated copper powder obtained by the preparation method of the present application can make the integrity and density of the silver layer on the surface of the copper powder good under the condition of low silver content, and has strong antioxidant ability, thereby improving the service reliability of the silver-coated copper powder and saving production costs; the silver-coated copper powder obtained by the preparation method of the present application has good low-temperature sintering activity.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for preparing silver-coated copper powder with low-temperature sintering activity, characterized in that: The preparation method comprises the following steps: mixing copper powder, a reducing agent, a complexing agent composition and a silver plating solution, reacting to obtain the silver-coated copper powder; The complexing agent composition comprises at least two of ammonia water, triethylenetetramine, ethylenediamine, diethanolamine, benzimidazole, tartaric acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, and glycine.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the copper powder to the complexing agent composition is 100:(10-40); Preferably, the shape of the copper powder includes any one of spherical, quasi-spherical, flake or polyhedral; Preferably, the copper powder has a Dv50 particle size of 1 to 8 μm.

3. The preparation method according to claim 1 or 2, characterized in that: The copper powder is surface treated before mixing, and then mixed with water to form a copper powder solution; Preferably, the surface treatment method includes pickling with acid solution; Preferably, the acid used in the acid solution includes any one of sulfuric acid, nitric acid or hydrochloric acid or a combination of at least two thereof; Preferably, the mass concentration of the acid solution is 1% to 5%; Preferably, the temperature of the water is 20 to 80°C; Preferably, the mass ratio of the copper powder to water is 1:(2-20).

4. The preparation method according to any one of claims 1 to 3, characterized in that The reducing agent includes any one of ascorbic acid, formaldehyde, glucose, potassium tartrate, hydrazine hydrate or potassium sodium tartrate, or a combination of at least two thereof; Preferably, the reducing agent is mixed with the copper powder solution before the next step is performed; Preferably, in the mixture of the reducing agent and the copper powder solution, the concentration of the reducing agent is 0.01 to 1.00 mol / L; Preferably, the concentration of the silver plating solution is 0.01 to 2 mol / L; Preferably, the complexing agent composition is first mixed with the silver plating solution, and then mixed with the copper powder and the reducing agent.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The reaction time is 20 to 120 minutes; Preferably, the reaction further includes washing, separation and drying; Preferably, the solvent used in the washing comprises water; Preferably, the separation method includes filter press separation; Preferably, the drying temperature is 40 to 80° C., and / or the drying time is 6 to 48 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) firstly pickling copper powder with a Dv50 particle size of 1 to 8 μm, and then mixing it with water at 20 to 80° C., wherein the mass ratio of the copper powder to the water is 1:(2 to 20), to form a copper powder solution; Mixing the complexing agent composition with a silver plating solution having a concentration of 0.01 to 2 mol / L to form a silver plating solution containing the complexing agent composition; (2) The copper powder solution is first mixed with a reducing agent, and then mixed with a silver plating solution containing a complexing agent composition, reacted for 20 to 120 minutes, and then washed, separated and dried to obtain the silver-coated copper powder.

7. A silver-coated copper powder, characterized in that: The silver-coated copper powder is obtained by the preparation method according to any one of claims 1 to 6; Preferably, based on the total mass of the silver-coated copper powder being 100%, the mass content of silver is 5% to 20%, and more preferably 5% to 15%; Preferably, the shape of the silver-coated copper powder includes a polyhedron.

8. A silver-coated copper powder composition having low-temperature sintering activity, characterized in that: The silver-coated copper powder composition comprises a surface modifier and the silver-coated copper powder obtained by the preparation method according to any one of claims 1 to 6, or the silver-coated copper powder according to claim 7.

9. The silver-coated copper powder composition according to claim 8, characterized in that: The mass ratio of the surface modifier to the silver-coated copper powder is (0.5-50):1000; Preferably, the surface modifier comprises one or more of oleic acid, oleamide, lactic acid, oxalic acid, linolenic acid, malic acid, stearic acid, palmitic acid, lauric acid, polyaspartic acid, cysteine, glutamic acid, mercaptoalanine, formic acid, acetic acid, phenyltriazole, methylbenzotriazole, sodium mercaptobenzothiazole, glycidyloxypropyltrimethylsilane, 3-glycidyloxypropylmethyldiethoxysilane, aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, diethylenetriaminopropyltrimethoxysilane; Preferably, the preparation method of the silver-coated copper powder composition comprises the following steps: (1) firstly pickling copper powder with a Dv50 particle size of 1 to 8 μm, and then mixing it with water at 20 to 80° C., wherein the mass ratio of the copper powder to the water is 1:(2 to 20), to form a copper powder solution; Mixing the complexing agent composition with a silver plating solution having a concentration of 0.01 to 2 mol / L to form a silver plating solution containing the complexing agent composition; (2) The copper powder solution is first mixed with a reducing agent, and then mixed with a silver plating solution containing a complexing agent composition, reacted for 20 to 120 minutes, and then washed, separated, added with a surface modifier, mixed and dried to obtain the silver-coated copper powder composition, i.e., silver-coated copper powder containing a surface modifier.

10. The silver-coated copper powder composition according to claim 8 or 9, characterized in that: The silver-coated copper powder composition further comprises submicron silver powder and a solvent.

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