Film-shaped copper powder, preparation method thereof and electronic component

Abstract

The invention relates to the technical field of copper powder preparation, in particular to film-shaped copper powder, a preparation method thereof and an electronic component. The preparation method of the thin-film-shaped copper powder comprises the following steps that organic copper salt, polyvinyl alcohol, a solvent and a dispersing agent are mixed, the mixed system is subjected to high-pressure homogenization, and organic copper dispersion liquid is obtained; and the organic copper dispersion liquid and a reducing agent are mixed for reaction and dried, and thin-film-shaped copper powder is obtained. The thin-film-shaped copper powder is prepared through a chemical reduction direct template method, one-step reaction is achieved, consumed time is short, and operation is easy; by means of the method, a large amount of thin-film-shaped copper powder can be prepared, and the obtained product is high in morphology controllability, uniform and stable; the film-shaped copper powder is prepared under the water-based condition, and environment friendliness is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of copper powder preparation, and particularly relates to a thin-film copper powder, a preparation method thereof, and an electronic component. Background Art

[0002] With the rapid development of the electronics industry, the application field of conductive pastes is becoming more and more extensive, and the usage amount is also increasing year by year. Currently, the vast majority of pastes in the market have silver powder as the conductive phase. The advantages are stability and good conductivity, while the disadvantage is high price, and the market competition for the same type of pastes is fierce. Therefore, there are already pastes on the market with silver-coated copper or copper replacing silver as the conductive phase. With their excellent conductivity, low price, good dispersibility and other characteristics, copper pastes have developed rapidly in recent years.

[0003] As an important component of the conductive phase in electronic pastes, copper powder is widely used in conductive pastes, conductive adhesives and other aspects. The morphology and particle size of copper powder have a great influence on the conductivity of the paste. The most commonly used copper powders currently generally include spherical and flake-shaped ones. Among them, spherical copper powder mainly has point contact with a smaller contact area, while flake-shaped copper powder generally has surface contact, and moreover, it has a larger specific surface area. Therefore, the copper conductor paste prepared from flake-shaped copper powder has better conductivity. Currently, the most widely used copper powders in the field of printed electronics are nano-copper powder and flake-shaped copper powder.

[0004] Due to its relatively large specific surface area, when sintering, because the film layer shrinks, the copper flakes come into contact with each other, forming line contact or surface contact, so the resistance is relatively low and the conductivity is good. Flake-shaped copper powder is mainly applied to high-end electronics or special flexible electronics fields. The common preparation processes of flake-shaped copper powder mainly include: mechanically ball-milling pure copper powder. The flake-shaped copper powder obtained by this method has different shapes and sizes, poor surface flatness, and weak conductivity.

[0005] Thin-film copper powder is a flake-shaped copper powder with a higher aspect ratio, that is, the ratio of the length to the thickness of the copper powder can reach more than 50. In the application of copper paste, in addition to forming the same line / surface contact as that of flake-shaped copper between copper particles, a conductive mode of tight overlapping of upper and lower copper flakes can also be formed. Under this structure, the contact area between conductive layers in the application of copper paste is larger, it is easy to stretch, fold, and bend, and the conductivity is more excellent. At the same time, the thin-film copper powder has a high aspect ratio and a large surface area, with strong anti-fracture and excellent tensile properties. The electronic components prepared therefrom also have very strong reliability. Compared with other morphologies of copper powder in the fields of flexible printed electronics, flexible stretchable electronics, etc., thin-film copper powder can show more extensive applicability due to the above advantages. At the same time, compared with the copper paste coatings prepared from other morphologies of copper powder with the same mass, the thin-film copper powder can not only reduce the amount of copper powder used but also reduce the coating thickness, greatly reducing the cost, and also facilitating the miniaturization development of electronic components.

[0006] In the prior art, ball milling method and electroless plating method are often used to prepare flaky copper powder. For example, in the ball milling method, copper powder is used as the raw material, and a conductive carbon material is added as a dispersant, and then ball milling is carried out to obtain flaky copper powder. In the preparation process of the flaky copper powder provided by the present invention, a conductive carbon material is added as a dispersant, which solves the passivation effect on the electrical conductivity of the flaky copper powder caused by using a surfactant as a dispersant in the prior art, and saves the pretreatment process of the flaky copper powder; the process is simple, the conditions are mild, the operation is convenient, and it is easy to realize large-scale production; the obtained flaky copper powder has high electrical conductivity and small resistance, and is very suitable for use as a conductive filler. However, the mechanical ball milling process takes a long time, large-scale operation cannot be carried out to ensure the ball milling effect, there are many variables in the ball milling process, the results are not easy to be unified under the same technical conditions, the batch stability is poor, impurities are easily introduced during ball milling, reducing the purity of copper powder and affecting the performance, and it is difficult to control the particle size and morphology uniformity of copper flakes. For example, in the electroless plating method, water, copper salt, complexing agent, copper plating brightener, dispersant, antioxidant, nickel salt, sublimable flaky compound crystallization template or acid-containing compound crystallization template or flaky alkaline compound crystallization template, and reducing agent are used as raw materials, and by using the electroless plating method, copper is plated on the surface of the compound crystallization template until the copper ions react completely. After the reaction is completed, through the processes of separation, purification and processing, without ball milling, flaky copper powder is directly obtained. However, the process of the electroless plating method is complex, requires multiple steps to complete, has high cost, expensive equipment and raw materials, long reaction cycle, high production cost, limited output and low efficiency. In addition, the electroless plating waste water and waste gas may cause environmental pollution.

[0007] Therefore, the preparation process of the thin film copper powder urgently needs to be improved. Summary of the Invention

[0008] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. For this reason, the present invention provides a thin film copper powder, a preparation method thereof, and an electronic component. The method of the present invention can prepare a large amount of thin film copper powder, and the obtained product has a high degree of controllability of morphology, and is uniform and stable.

[0009] For this reason, the first aspect of the present invention provides a method for preparing a thin film copper powder, including the following steps:

[0010] Mix an organic copper salt, polyvinyl alcohol, a solvent and a dispersant, and perform high-pressure homogenization on the mixed system to obtain an organic copper dispersion;

[0011] Mix the organic copper dispersion and a reducing agent to react, and dry to obtain the thin film copper powder.

[0012] The present invention prepares film-like copper powder by a chemical reduction direct template method, which is a one-step reaction, time-consuming short, simple and easy to operate; the method of the present invention can prepare a large amount of film-like copper powder, and the morphology controllability of the obtained product is high, uniform and stable; the present invention prepares film-like copper powder under aqueous conditions, which is environmentally friendly.

[0013] In some embodiments of the present invention, the mass ratio of the organic copper salt to the polyvinyl alcohol is (10-20):1. Thus, the polyvinyl alcohol can form a hydrated layer, further improving the dispersion uniformity of the organic copper salt in the system and reducing the growth and aggregation of copper particles.

[0014] In some embodiments of the present invention, the mass ratio of the organic copper salt to the dispersant is (1-10):1. Thus, the dispersion uniformity of the organic copper salt in the system can be further improved.

[0015] In some embodiments of the present invention, based on the mass of the organic copper dispersion, the mass concentration of the organic copper salt is 4%-10%. Thus, it helps to control the reaction efficiency of the organic copper salt and the reducing agent.

[0016] In some embodiments of the present invention, the pressure of the high-pressure homogenization is 100-300 bar. High-pressure homogenization can make the organic copper salt highly homogenized in the system under the action of high pressure, high-speed shearing and cavitation effects.

[0017] In some embodiments of the present invention, the temperature of the reduction is 40-60 °C.

[0018] In some embodiments of the present invention, the organic copper salt includes one or more of copper stearate, copper behenate, copper laurate and copper succinate. When preparing copper powder with an organic copper salt, copper powder with smaller particle size and more uniform distribution can be prepared by processes such as chemical reduction method. In particular, using an organic copper salt as a raw material and controlling the reaction conditions at the same time, copper powder with a nano-scale particle size can be generated.

[0019] In some embodiments of the present invention, the dispersant includes an amphoteric surfactant; the amphoteric surfactant includes one or more of tetradecyldimethylpropylsulfonate, 1,3-(N,N-dimethyldodecylammonium) propane sulfonate, lauryldimethylsulfobetaine, N-dodecyldimethyl(3-sulfopropyl) ammonium hydroxide inner salt, 3-sulfopropyldodecyldimethylbetaine.

[0020] In some embodiments of the present invention, a reducing agent is used to reduce the organic copper dispersion.

[0021] In some embodiments of the present invention, the reducing agent includes one or more of glucose, hydroquinone, ascorbic acid, sodium hypophosphite, hydrazine hydrate.

[0022] In some embodiments of the present invention, the temperature of the drying is 40 - 60 °C and the time is 0.5 - 1 h.

[0023] The second aspect of the present invention provides a film-like copper powder prepared by the above preparation method.

[0024] The third aspect of the present invention provides an electronic component, comprising the film-like copper powder prepared by the above preparation method and / or the film-like copper powder described above.

[0025] The additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0027] Figure 1 Shows the scanning electron micrograph of the film-like copper powder of Example 1 of the present invention;

[0028] Figure 2 Shows the scanning electron micrograph of the copper powder of Comparative Example 4 of the present invention. Detailed Description of the Embodiments

[0029] The embodiments of the present invention will be described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] It should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0031] The first aspect of the present invention provides a method for preparing a film-like copper powder, comprising the following steps:

[0032] Mix an organic copper salt, polyvinyl alcohol, a solvent and a dispersant, and perform high-pressure homogenization on the mixed system to obtain an organic copper dispersion;

[0033] Mix the organic copper dispersion and a reducing agent for reaction, and dry to obtain a film-like copper powder.

[0034] The present invention prepares film-shaped copper powder by a chemical reduction direct template method, which involves a one-step reaction, takes a short time, and is simple and easy to operate. The method of the present invention can prepare film-shaped copper powder in large quantities, and the morphology controllability of the obtained product is high, uniform and stable. The present invention prepares film-shaped copper powder under aqueous conditions, which is environmentally friendly.

[0035] In some embodiments of the present invention, the organic copper salt includes one or more of copper stearate, copper behenate, copper laurate, and copper succinate. When preparing copper powder, the organic copper salt can prepare copper powder with smaller particle size and more uniform distribution through processes such as chemical reduction method. In particular, using the organic copper salt as a raw material and controlling the reaction conditions simultaneously can generate copper powder with a nano-level particle size.

[0036] In some embodiments of the present invention, the solvent includes organic solvents and water; the organic solvents include one or more of hydrocarbon solvents, alcohol solvents, ketone solvents, phenol solvents, and ester solvents; the alcohol solvents include one or more of ethanol, ethylene glycol, isopropanol, diethylene glycol, and glycerol.

[0037] In some embodiments of the present invention, the dispersant includes amphoteric surfactants; the amphoteric surfactants include one or more of tetradecyldimethylpropylsulfonate, 1,3-(N,N-dimethyldodecylammonium) propane sulfonate, lauryldimethylsulfobetaine, N-dodecyldimethyl(3-sulfopropyl) ammonium hydroxide inner salt, and 3-sulfopropyldodecyldimethylbetaine.

[0038] In some embodiments of the present invention, the mass ratio of the organic copper salt to the polyvinyl alcohol is (10-20):1. As an example, the mass ratio of the organic copper salt to the polyvinyl alcohol can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1. Thus, the polyvinyl alcohol can form a hydrated layer, further improving the dispersion uniformity of the organic copper salt in the system and reducing the growth and aggregation of copper particles.

[0039] In some embodiments of the present invention, the mass ratio of the organic copper salt to the dispersant is (1-10):1. As an example, the mass ratio of the organic copper salt to the dispersant can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1. Thus, the dispersion uniformity of the organic copper salt in the system can be further improved.

[0040] The present invention has no special limitation on the usage amount of the solvent, as long as it can dissolve the organic copper salt.

[0041] In some embodiments of the present invention, the mixing of the organic copper salt, polyvinyl alcohol, solvent, and dispersant is carried out under stirring; the stirring speed is 500 - 1000 r / min, and the time is 1 - 2 h.

[0042] In some embodiments of the present invention, the mixing of the organic copper salt, solvent, and dispersant specifically includes: mixing the organic copper salt, solvent, organic solvent, and dispersant, and then mixing with polyvinyl alcohol.

[0043] In some embodiments of the present invention, the pressure of the high-pressure homogenization is 100 - 300 bar. High-pressure homogenization can make the organic copper salt highly homogenized in the system under the action of high pressure, high-speed shearing, and cavitation effect. As an example, the pressure of high-pressure homogenization can be 100, 150, 200, 250, 300 bar. The organic copper dispersion after high-pressure homogenization is more uniform, and in the subsequent reaction, the organic copper can contact the reducing agent more stably, react to generate copper crystal nuclei, ensure that the particle size of the crystal nuclei is uniform, grow at a uniform speed, and finally a film-like copper powder with the same uniform particle size can be obtained.

[0044] In some embodiments of the present invention, based on the mass of the organic copper dispersion, the mass concentration of the organic copper salt is 4% - 10%. As an example, based on the mass of the organic copper dispersion, the mass concentration of the organic copper salt can be 4%, 5%, 6%, 7%, 8%, 9%, or 10%. Thus, it helps to control the reaction efficiency of the organic copper salt and the reducing agent.

[0045] In some preferred embodiments of the present invention, based on the mass of the organic copper dispersion, the mass concentration of the organic copper salt is 4% - 8%.

[0046] In some embodiments of the present invention, a reducing agent is used to reduce the organic copper dispersion.

[0047] In some embodiments of the present invention, the reducing agent includes one or more of glucose, hydroquinone, ascorbic acid, sodium hypophosphite, and hydrazine hydrate.

[0048] The present invention has no special requirements for the dosage of the reducing agent. The conventional dosage in the art is used to reduce the organic copper dispersion. In some embodiments of the present invention, the molar ratio of the organic copper salt to the reducing agent is (2 - 4):1. As an example, the molar ratio of the organic copper salt to the reducing agent can be 2:1, 3:1, 4:1.

[0049] In some embodiments of the present invention, the molar ratio of the organic copper salt to ascorbic acid is (2 - 4):1.

[0050] In some embodiments of the present invention, the reducing agent is mixed with the organocopper dispersion in the form of a solution; based on the mass of the reducing agent solution, the mass concentration of the reducing agent is 2%-8%. As an example, based on the mass of the reducing agent solution, the mass concentration of the reducing agent can be 2%, 3%, 4%, 5%, 6%, 7% or 8%.

[0051] In some embodiments of the present invention, the reduction temperature is 40-60°C. As an example, the reduction can be carried out at 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60°C.

[0052] In some embodiments of the present invention, the reduction time is 1-2 h. As an example, the reduction time can be 1, 1.5, 2 h.

[0053] In some embodiments of the present invention, the drying temperature is 40-60°C and the time is 0.5-1 h.

[0054] The second aspect of the present invention provides a film-like copper powder prepared by the above preparation method.

[0055] In some embodiments of the present invention, the loose bulk density of the film-like copper powder is 0.4-0.8 g / cm 3 , and the tapped density is 1-1.5 g / cm 3 . The loose bulk density and tapped density of the film-like copper powder of the present invention are relatively small, the amount of copper powder used is less under the same conditions, it can be used for lightweight applications, and the cost is relatively low. As an example, the loose bulk density of the film-like copper powder can be 0.4, 0.5, 0.6, 0.7, 0.8 g / cm 3 , and the tapped density can be 1, 1.1, 1.2, 1.3, 1.4, 1.5 g / cm 3 .

[0056] In some embodiments of the present invention, the average particle size of the film-like copper powder is 2-8 μm. As an example, the average particle size of the film-like copper powder can be 2, 3, 4, 5, 6, 7, 8 μm.

[0057] In some embodiments of the present invention, the average thickness of the film-like copper powder is 100-200 nm. As an example, the average thickness of the film-like copper powder can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 nm.

[0058] The third aspect of the present invention provides an electronic component, including the film-like copper powder prepared by the above preparation method and / or the film-like copper powder as described above.

[0059] The solutions of the present disclosure will be explained below in conjunction with embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. For those embodiments where specific techniques or conditions are not indicated, the techniques or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchases.

[0060] Example 1

[0061] For the flaky copper powder of this example, the morphology of the copper powder was tested by scanning electron microscopy and was flaky, as Figure 1 shown. The apparent density was 0.6 g / cm 3 , the tapped density was 1.2 g / cm 3 , the average particle size was 5 μm, and the average thickness was 150 nm. The preparation method included the following steps:

[0062] (1) Mix cupric behenate powder (60 g, 0.08 mol), 120 g of ethanol, and 15 g of dispersant (tetradecyldimethylaminopropyl sulfonate), and add 745 g of water to fully wet. In a high-pressure homogenizer, the pressure was set to 300 bar, the number of cycles was 1 time, and 60 g of an aqueous solution of 5 wt% polyvinyl alcohol (the mass of polyvinyl alcohol was 3 g) was added under the condition of paddle stirring at 500 r / min and stirred for 2 hours to obtain a 6 wt% cupric behenate dispersion.

[0063] (2) Dissolve the reducing agent ascorbic acid (42 g, 0.24 mol) in water to obtain 840 g of a reducing agent solution. The molar ratio of the reducing agent to cupric behenate was 3:1.

[0064] (3) Using a single-injection process, add the above cupric behenate dispersion into a reaction tank. Under the condition of paddle stirring at 50 °C, inject the reducing agent solution into the reaction tank at a speed of 15 mL / min. After the injection is completed, keep the temperature and stirring conditions unchanged, continue to keep warm and react for 1 h, and then filter, wash with water, and dry at 50 °C for 45 min to obtain the flaky copper powder.

[0065] Example 2

[0066] For the flaky copper powder of this example, the apparent density was 0.8 g / cm 3 , the tapped density was 1.5 g / cm 3 , the average particle size was 2 μm, and the average thickness was 100 nm. The preparation method included the following steps:

[0067] (1) Mix 40 g of copper behenate powder, 80 g of ethanol, and 10 g of dispersant (tetradecyldimethylaminopropyl sulfonate), add 830 g of water and soak thoroughly. In a high-pressure homogenizer, set the pressure to 100 bar, the number of cycles to 1, and under the condition of paddle stirring at 500 r / min, add 40 g of an aqueous solution of 5 wt% polyvinyl alcohol (the mass of polyvinyl alcohol is 2 g) and stir thoroughly for 2 hours to obtain a copper behenate dispersion with a concentration of 4 wt%.

[0068] (2) Dissolve 19 g of reducing agent ascorbic acid in water to obtain 633 g of reducing agent solution, and the molar ratio of the reducing agent to copper behenate is 2:1.

[0069] (3) Using the single-injection process, add the above copper behenate dispersion into the reaction tank. Under the condition of paddle stirring at 40 °C, inject the reducing agent solution into the reaction tank at a speed of 10 mL / min. After the injection is completed, keep the conditions unchanged and continue the heat preservation reaction for 1 h, then filter, wash with water, and dry at 40 °C for 1 h to obtain film-like copper powder.

[0070] Example 3

[0071] The film-like copper powder of this example has a loose bulk density of 0.4 g / cm 3 , a tapped density of 1.0 g / cm 3 , an average particle size of 200 μm, and an average thickness of 8 nm. The preparation method includes the following steps:

[0072] (1) Mix 80 g of copper behenate powder, 160 g of ethanol, and 20 g of dispersant (tetradecyldimethylaminopropyl sulfonate), add 660 g of water and soak thoroughly. In a high-pressure homogenizer, set the pressure to 300 bar, the number of cycles to 1, and under the condition of paddle stirring at 500 r / min, add 80 g of an aqueous solution of 5 wt% polyvinyl alcohol (the mass of polyvinyl alcohol is 4 g) and stir thoroughly for 2 hours to obtain a copper behenate dispersion with a concentration of 8 wt%.

[0073] (2) Dissolve 76 g of reducing agent ascorbic acid in water to obtain 950 g of reducing agent solution, and the molar ratio of the reducing agent to copper behenate is 4:1.

[0074] (3) Using the single-injection process, add the above copper behenate dispersion into the reaction tank. Under the condition of paddle stirring at 60 °C, inject the reducing agent solution into the reaction tank at a speed of 20 mL / min. After the injection is completed, keep the conditions unchanged and continue the heat preservation reaction for 1 h, then filter, wash with water, and dry at 60 °C for 0.5 h to obtain film-like copper powder.

[0075] Comparative Example 1

[0076] The copper powder of this comparative example has a loose bulk density of 0.3 g / cm3 , the tapped density is 0.9 g / cm 3 , the average particle size is 10 μm, and the average thickness is 300 nm; The preparation method of the copper powder in this comparative example is only different from that in Example 1 in that: the concentration of the copper behenate dispersion liquid in this comparative example is set to 10 wt%; the remaining steps are carried out with reference to the method in Example 1.

[0077] The preparation method specifically includes the following steps:

[0078] (1) Mix 100 g of copper behenate powder, 200 g of ethanol, and 25 g of dispersant (tetradecyldimethylamine propyl sulfonate), and add 575 g of water to fully soak. In a high-pressure homogenizer, the pressure is set to 300 bar, the number of cycles is 1, and 100 g of an aqueous solution of 5 wt% polyvinyl alcohol (the mass of polyvinyl alcohol is 5 g) is added under the condition of paddle stirring at 500 r / min and stirred for 2 hours to obtain a copper behenate dispersion liquid with a concentration of 10 wt%.

[0079] (2) Dissolve the reducing agent ascorbic acid (42 g, 0.24 mol) in water to obtain 840 g of a reducing agent solution, and the molar ratio of the reducing agent to copper behenate is 3:1.

[0080] (3) Adopt a single-injection process, add the above copper behenate dispersion liquid into a reaction tank, and under the condition of paddle stirring at 50 °C, inject the reducing agent solution into the reaction tank at a speed of 15 mL / min. After the injection is completed, keep the temperature and stirring conditions unchanged, continue to keep the temperature for reaction for 1 h, and then filter, wash with water, and dry at 50 °C for 45 min to obtain copper powder.

[0081] Comparative Example 2

[0082] The loose bulk density of the copper powder in this comparative example is 0.9 g / cm 3 , the tapped density is 1.8 g / cm 3 , the average particle size is 1 μm, and the average thickness is 200 nm; The preparation method of the copper powder in this comparative example is only different from that in Example 1 in that: the molar ratio of ascorbic acid reducing agent to copper behenate in this comparative example is 1:1; the remaining steps are carried out with reference to the method in Example 1.

[0083] (1) Mix copper behenate powder (60 g, 0.08 mol), 120 g of ethanol, and 15 g of dispersant (tetradecyldimethylamine propyl sulfonate), and add 745 g of water to fully soak. In a high-pressure homogenizer, the pressure is set to 300 bar, the number of cycles is 1, and 60 g of an aqueous solution of 5 wt% polyvinyl alcohol (the mass of polyvinyl alcohol is 3 g) is added under the condition of paddle stirring at 500 r / min and stirred for 2 hours to obtain a copper behenate dispersion liquid with a concentration of 6 wt%.

[0084] (2) Dissolve the reducing agent ascorbic acid (0.08 mol) in water to obtain a reducing agent solution, and the molar ratio of the reducing agent to copper behenate is 1:1.

[0085] (3) Using the single-injection process, add the above-mentioned copper behenate dispersion into the reaction tank. Under the condition of paddle stirring at 50 °C, inject the reducing agent solution into the reaction tank at a speed of 15 mL / min. After the injection is completed, keep the temperature and stirring conditions unchanged, continue the heat preservation reaction for 1 h, and then obtain copper powder through filtration, washing with water, and drying at 50 °C for 45 min.

[0086] Comparative Example 3

[0087] The loose bulk density of the copper powder in this comparative example is 0.8 g / cm 3 , and the tapped density is 1.5 g / cm 3 , the average particle size is 2 μm, and the average thickness is 250 nm; the preparation method of the copper powder in this comparative example is only different from that of Example 1 in that: in step (3) of this comparative example, the reaction temperature is set to 70 °C; the remaining steps are carried out according to the method in Example 1.

[0088] The preparation method specifically includes the following steps:

[0089] (1) Mix copper behenate powder (60 g, 0.08 mol), 120 g of ethanol, and 15 g of dispersant (tetradecyldimethylaminopropyl sulfonate), and add 745 g of water to fully wet. In a high-pressure homogenizer, the pressure is set to 300 bar, the number of cycles is 1 time, and 60 g of an aqueous solution of 5 wt% polyvinyl alcohol (the mass of polyvinyl alcohol is 3 g) is added under the condition of paddle stirring at 500 r / min and stirred for 2 hours to obtain a 6 wt% copper behenate dispersion.

[0090] (2) Dissolve the reducing agent ascorbic acid (42 g, 0.24 mol) in water to obtain 840 g of a reducing agent solution, and the molar ratio of the reducing agent to copper behenate is 3:1.

[0091] (3) Using the single-injection process, add the above-mentioned copper behenate dispersion into the reaction tank. Under the condition of paddle stirring at 70 °C, inject the reducing agent solution into the reaction tank at a speed of 15 mL / min. After the injection is completed, keep the temperature and stirring conditions unchanged, continue the heat preservation reaction for 1 h, and then obtain copper powder through filtration, washing with water, and drying at 50 °C for 45 min.

[0092] Comparative Example 4

[0093] The morphology of the copper powder in this comparative example was tested by scanning electron microscopy and was not film-like but showed thick plate-like, as Figure 2 shown, the loose bulk density of the copper powder is 1.5 g / cm 3, the tap density is 2.9 g / cm 3 , the average particle size is 20 μm, and the average thickness is 2 - 4 μm; the difference between the preparation method of the copper powder in this comparative example and that in Example 2 is only that: in this comparative example, polyvinylpyrrolidone (PVP) is used instead of polyvinyl alcohol (PVA) to disperse organic copper; the remaining steps are carried out with reference to the method in Example 2.

[0094] The preparation method specifically includes the following steps:

[0095] (1) Mix 40 g of copper behenate powder, 80 g of ethanol, and 10 g of dispersant (tetradecyldimethylaminopropyl sulfonate), and add 830 g of water to fully wet. In a high-pressure homogenizer, the pressure is set to 100 bar, the number of cycles is 1, and 40 g of an aqueous solution of 5 wt% PVP (the mass of PVP is 2 g) is added under the condition of 500 r / min paddle stirring and stirred for 2 hours to obtain a copper behenate dispersion with a concentration of 4 wt%.

[0096] (2) Dissolve 19 g of the reducing agent ascorbic acid in water to obtain 633 g of a reducing agent solution, and the molar ratio of the reducing agent to copper behenate is 2:1.

[0097] (3) Adopt a single-injection process, add the above-mentioned copper behenate dispersion into a reaction tank, and under the condition of 40°C paddle stirring, inject the reducing agent solution into the reaction tank at a speed of 10 mL / min. After the injection is completed, keep the conditions unchanged and continue the heat preservation reaction for 1 h, and then filter, wash with water, and dry at 40°C for 1 h to obtain copper powder.

[0098] Test Example

[0099] Add the copper powders of the above Examples 1 - 3 and Comparative Examples 1 - 4 into polyurethane (PU) resin and dibasic acid ester (DBE) with a mass ratio of 3:7 respectively to obtain a mixed solvent. Add functional additives such as a leveling agent, a dispersant, and an antioxidant into the mixed solvent, and stir and disperse evenly to obtain a copper paste with a copper content of 60 wt%; the leveling agent is polyacrylate, and the addition amount is 0.5 wt% of the mixed solvent; the dispersant is BYK - 110 (purchased from BYK Chemie), and the addition amount is 2 wt% of the mixed solvent; the antioxidant is phosphite, and the addition amount is 0.5 wt% of the mixed solvent.

[0100] Use the above copper paste as a printing material, print 1 mm wires and circular electrodes with a diameter of 2 cm on a thermoplastic polyurethane elastomer (TPU) film with a 200 - mesh screen. Set the standard parameters of the M - 3 type handheld four - probe tester produced by Suzhou Jingge Electronics Co., Ltd., and test the sheet resistance after stretching (stretching 10%, stretching 100 times) at the wire and the sheet resistance of the electrode piece. The experimental results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As can be seen from Table 1, the initial sheet resistance of the circuit, the sheet resistance of the circuit after stretching, and the sheet resistance of the electrode sheet prepared from the copper powder obtained in Examples 1-3 of the present invention are all smaller than those in Comparative Examples 1-4.

[0104] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", "some implementation manners" or "some examples", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0105] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a thin-film copper powder, characterized in that, It includes the following steps: Mix an organic copper salt, polyvinyl alcohol, a solvent and a dispersant, and perform high-pressure homogenization on the mixed system to obtain an organic copper dispersion; Reduce and dry the organic copper dispersion to obtain film-like copper powder.

2. The method for preparing the thin-film copper powder according to claim 1, wherein The mass ratio of the organic copper salt to the polyvinyl alcohol is (10 - 20):

1.

3. The method for preparing the thin-film copper powder according to claim 1, wherein The mass ratio of the organic copper salt to the dispersant is (1 - 10):

1.

4. The method for preparing the thin-film copper powder according to claim 1, wherein Based on the mass of the organic copper dispersion, the mass concentration of the organic copper salt is 4% - 10%.

5. The method for preparing the thin-film copper powder according to claim 1, wherein The pressure of the high-pressure homogenization is 100 - 300 bar.

6. The method for preparing the thin-film copper powder according to claim 1, wherein The temperature of the reduction is 40 - 60 °C.

7. The method for preparing the thin-film copper powder according to claim 1, wherein The organic copper salt includes one or more of copper stearate, copper behenate, copper laurate and copper succinate; And / or, the dispersant includes an amphoteric surfactant; And / or, the amphoteric surfactant includes one or more of tetradecyldimethylpropylsulfonate, 1,3-(N,N-dimethyldodecylammonium) propane sulfonate, lauryldimethylsulfobetaine, N-dodecyldimethyl(3-sulfopropyl) ammonium hydroxide inner salt, 3-sulfopropyldodecyldimethylbetaine; And / or, the organic copper dispersion is reduced using a reducing agent; Optionally, the reducing agent includes one or more of glucose, hydroquinone, ascorbic acid, sodium hypophosphite, hydrazine hydrate.

8. The method for preparing the thin-film copper powder according to claim 1, wherein The temperature of the drying is 40 - 60 °C, and the time is 0.5 - 1 h.

9. The film-like copper powder prepared by the method for preparing a film-like copper powder according to any one of claims 1 - 8.

10. An electronic component, characterized in that, It includes the film-like copper powder prepared by the method for preparing a film-like copper powder according to any one of claims 1 - 8 and / or the film-like copper powder according to claim 9.

Images