Inorganic coated copper powder and preparation method thereof, and conductive paste composition

Abstract

The present application discloses an inorganic-coated copper powder, a preparation method thereof, and a conductive paste composition. The inorganic-coated copper powder includes a Cu core body and an inorganic coating structure coated on the surface of the Cu core body. The inorganic coating structure includes a SiO2-B2O3 compound. The Cu core body is a spherical body, the particle size of the Cu core body is 0.1-3 μm, the area of the inorganic coating structure covering the Cu core body is not less than 50% of the surface area of the Cu core body, and the mass ratio of the inorganic coating structure to the Cu core body is (11-14):(86-89). The inorganic-coated copper powder has good oxidation resistance.

Description

Technical Field

[0001] The present application relates to the field of materials, and in particular to inorganic coated copper powder, conductive slurry and a preparation method thereof. Background Art

[0002] Ultrafine copper powder, such as copper powder with a particle size of several microns or even nanometers, has good electrical properties and is cheaper than precious metals such as silver powder and palladium powder, so it is expected to replace silver powder in conductive paste. In addition, with the development of semiconductor technology, the requirements for the conductivity, high temperature resistance and oxidation resistance of conductive paste have also increased.

[0003] The Cu powder prepared by the condensation evaporation method is used to prepare high-performance ultrafine copper powder because of its clean surface and uniform particle size. However, the surface of the high-performance copper powder prepared by the condensation evaporation method generally does not have a coating structure, and due to its small particle size, its oxidation resistance is poor.

[0004] Therefore, the current inorganic coated copper powder, conductive slurry and preparation method thereof still need to be improved. Summary of the invention

[0005] In view of the above problems, the present application provides an inorganic coated copper powder and a preparation method thereof, and a conductive paste composition.

[0006] In one aspect of the present application, the present application proposes an inorganic coated copper powder. The inorganic coated copper powder comprises a Cu core body and an inorganic coating structure coated on the surface of the Cu core body, wherein the inorganic coating structure comprises SiO 2 -B 2 O 3 The compound, the Cu core is a spherical body, the particle size of the Cu core is 0.1-3 μm, the area of ​​the Cu core covered by the inorganic coating structure is not less than 50% of the surface area of ​​the Cu core, and the mass ratio of the inorganic coating structure to the Cu core is (11-14): (86-89); the inorganic coating structure further includes a dispersing additive, the dispersing additive includes an amphiphilic molecule containing silane and / or silanol, and the dispersing additive is formed in the SiO 2 -B 2 O 3 The compound was previously added to the reaction solution, the SiO 2 -B 2 O 3 The compound is coated on the surface of the Cu core by mechanical mixing. The inorganic coated copper powder has the advantages of good oxidation resistance and little influence on the conductivity after being prepared into a conductive slurry, which can promote the SiO 2 -B 2 O 3 Formation of compounds.

[0007] According to an embodiment of the present application, the dispersing additive includes a compound represented by the following formula (1):

[0008] Formula (1),

[0009] Wherein R is H, methyl, ethyl or COCH 3 , a=1-50, R1 is methyl, ethyl, methoxy or hydroxyl. Thus, SiO 2 The dispersion of the crystal nucleus promotes the reaction of silicon source and boron source, thereby increasing the formed SiO 2 -B 2 O 3 The mass of the compound.

[0010] According to an embodiment of the present application, the SiO 2 -B 2 O 3 The mass ratio of the compound to the dispersing additive is 95:5 to 99:1. Thus, the dispersing effect can be fully exerted.

[0011] In another aspect of the present application, the present application proposes a method for preparing the inorganic coated copper powder described above. The method comprises: adding a dispersing additive to a solvent, and adding an organic silicon source and an organic boron source to obtain SiO 2 -B 2 O 3 Sol; in the SiO 2 -B 2 O 3 Cu powder is added to the sol, stirred and mixed, and then allowed to stand for 2-10 hours, and dried under inert atmosphere protection at a temperature of 150-250°C. This method is conducive to quickly and easily obtaining SiO 2 -B 2 O 3 Sol, improve the uniformity of the formed inorganic coating, and thus easily obtain high-quality inorganic coated copper powder.

[0012] According to the embodiment of the present application, the SiO 2 -B 2 O 3 Sol includes:

[0013] (1) adding the dispersing additive to an alcohol solution and adjusting the pH value to 8.5-10 with a NaOH solution;

[0014] (2) Add ethyl orthosilicate, stir and react for 10-30 minutes;

[0015] (3) Add tributyl borate, stir and react for 10-30 minutes.

[0016] According to an embodiment of the present application, the Cu powder is added to the SiO 2 -B 2 O 3 Before being added to the sol, the Cu powder and the SiO 2 -B 2 O 3 The sol is stirred and mixed at 200-400 rpm, and allowed to stand for 4-6 hours, the pickling is performed with hydrochloric acid, and the infiltration treatment is performed with formaldehyde. Thus, the quality of the obtained inorganic coated copper powder can be improved.

[0017] In another aspect of the present application, the present application proposes a composition for preparing a conductive paste, the composition comprising: conductive metal powder, the conductive metal powder being the aforementioned inorganic coated copper powder; a binder, the binder comprising at least one of a polyimide compound and an acrylate compound; a solvent, the solvent comprising at least one selected from a diol compound, a polyether compound and a silanol compound; an additive, the additive comprising at least one of a tackifier, a leveling agent, a defoamer and a coupling agent, wherein the mass percentage of the conductive metal powder is 80-85%, and the mass ratio of the binder, the solvent and the additive is: (7-10): (6-8): (2-6). The conductive paste prepared by the composition can form a coating with high conductivity, which is suitable for conductive bonding in the field of microelectronics.

[0018] According to an embodiment of the present application, the binder includes polyurethane-modified acrylate, the solvent includes diol, and the additive includes at least a tackifier and a coupling agent, thereby further improving the quality of the formed conductive paste.

[0019] According to an embodiment of the present application, based on the total mass of the composition, the composition includes: 80%-85% of the conductive metal powder, 6%-9% of the binder, 5%-7% of the solvent, 1%-3% of the tackifier, and 1%-2% of the coupling agent. This is conducive to further improving the quality of the conductive paste formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0021] Figure 1The present invention is a flowchart of the preparation method of some embodiments of the present application. DETAILED DESCRIPTION

[0022] The following embodiments of the technical solution of the present application are 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.

[0023] 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 description and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.

[0024] 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.

[0025] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0026] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "upper", "lower", "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0028] In one aspect of the present application, the present application proposes an inorganic coated copper powder. The inorganic coated copper powder comprises a Cu core body and an inorganic coating structure coated on the surface of the Cu core body, wherein the inorganic coating structure comprises SiO 2 -B 2 O3 The compound, the Cu core is spherical, the particle size of the Cu core is 0.1-3 μm, the area of ​​the Cu core covered by the inorganic coating structure is not less than 50% of the surface area of ​​the Cu core, and the mass ratio of the inorganic coating structure to the Cu core is (11-14): (86-89). The inorganic coated copper powder has the advantages of good oxidation resistance and little influence on the conductivity after being prepared into a conductive slurry.

[0029] As mentioned above, micro-nano-level Cu powder usually has poor antioxidant properties. Therefore, the antioxidant properties of copper powder can be improved by metal / non-metal coating. Metal coating can be used to improve the antioxidant properties of powders by coating Ni, Ag, etc., but the operation is complicated and the cost is high. Currently, commonly used non-metallic coatings include solutions such as silica sols, which coat the surface of copper powder with inorganic substances to form oxides such as silicon dioxide. However, if you want to obtain copper powder with good conductivity and antioxidant properties, when forming solutions such as silica sols, you need to carefully control the generation of inorganic oxides in the sol solution, so the operation is also relatively complicated and not suitable for industrial promotion. Therefore, if a method for preparing inorganic coated copper powder and its preparation method can be proposed, and coated copper powder with better performance can be obtained under relatively simple operations, it is expected to alleviate or even solve the above problems to a large extent.

[0030] The present invention is applied by forming the SiO 2 -B 2 O 3 The compound is pre-added with dispersing additives in the solvent to control the SiO 2 , B 2 O 3 The morphology of the silicon source and the boron source is obtained by hydrolysis reaction to obtain SiO 2 -B 2 O 3 Sol is coated on the surface of Cu powder (i.e. Cu core) by mechanical mixing, thus improving the uniformity of the coating layer and 2 -B 2 O 3 When the content is low, a more uniform and complete coating layer can be achieved, thereby improving the oxidation resistance of the coated copper powder.

[0031] In some embodiments, the Cu core body can be a copper powder with a particle size of several microns or even nanometers obtained by condensation evaporation. Specifically, the Cu raw material can be heated in an atmosphere of inert gas, and the condensation process can be controlled, and micrometer and nanometer particles with uniform particle size and high roundness can be obtained by sufficient condensation. The Cu core body obtained in this way has good performance and a narrow particle size distribution, so when it is coated in the later stage, it can also be covered by an inorganic coating more evenly.

[0032] In some examples, the Cu nucleus can be formed by replacing the reaction space with an inert gas under a certain vacuum, and then evaporating Cu at a temperature above 2,000 degrees to form Cu vapor, and then controlling the flow rate of the Cu vapor and the flow rate of the cooling medium to uniformly and quickly cool the Cu vapor to form Cu powder with good roundness and narrow particle size distribution. Increasing the vacuum and introducing an inert gas can reduce the evaporation temperature and inhibit some impurity atoms from mixing into the Cu-containing mixture. Controlling the condensation conditions can prevent the Cu nucleation rate from being too fast to form large particles, thereby improving the uniformity and roundness of the obtained particles.

[0033] According to an embodiment of the present application, the particle size of the Cu core body may be 0.1-3 μm. The particle size may be Dv50 obtained by a laser particle size analyzer, for example, in some embodiments, Dv50 may be 100 nm-2 μm. The shape of the Cu core body may be spherical, and the spherical Cu core body may improve the uniformity of the coating, and when forming the slurry, it is also more conducive to forming a denser film structure through particle sliding, thereby improving the conductive performance of the conductive slurry.

[0034] In some embodiments, the sphericity of the Cu core may be greater than 90%. The impurity content in the Cu core is relatively low, and may contain 0.005-0.05wt% carbon and 0.08-2.0wt% oxygen. According to an embodiment of the present application, the iron content in the Cu core is less than 0.01wt%, the aluminum content is less than 0.01wt%, the silicon content is less than 0.01wt%, the calcium content is less than 0.01wt%, the magnesium content is less than 0.01wt%, and the zirconium content is less than 0.01wt%.

[0035] According to an embodiment of the present application, the dispersing additive may include an amphiphilic compound containing polyether and silanol and siloxane structures. Polyether has good compatibility in alcohol solution, and silanol and siloxane structures can disperse the generated silicon dioxide nuclei well, so that smaller and more uniformly dispersed nuclei can be obtained. For example, the dispersing additive may include a compound shown in the following formula (1):

[0036] Formula (1),

[0037] Wherein R is H, methyl, ethyl or COCH 3 , a=1-50, R1 is methyl, ethyl, methoxy or hydroxyl. Thus, SiO 2 The dispersion of the crystal nucleus promotes the reaction of silicon source and boron source to obtain a more uniformly distributed SiO 2 -B 2 O 3 Sol, thereby increasing the formed SiO 2 -B 2 O3 The mass of the compound. For example, in some examples, R can be methyl or H, a can be 50, and R1 can be methyl or hydroxyl. The compound can be obtained by reacting a polyether with a hydroxyl group at the end with a silanol. The amphiphilic dispersant with the above structure has good amphiphilic properties and a small molecular weight, and is suitable for adding to the system to prepare high-performance coated copper powder.

[0038] According to an embodiment of the present application, the SiO 2 -B 2 O 3 The mass ratio of the compound to the dispersing additive is 95:5 to 99:1. Thus, the dispersing effect can be fully exerted.

[0039] In some embodiments, the mass ratio of the inorganic coating structure to the Cu core body can be (11-14): (86-89). For example, the mass ratio of the inorganic coating structure to the Cu core body can be 12:88. The inorganic coating structure contains a very small amount of the above-mentioned dispersing additives, SiO 2 -B 2 O 3 The compound is the main body of the inorganic coating structure. When the mass ratio of the inorganic coating structure to the Cu core is within the above range, the sol can provide a relatively complete coating for the Cu core, thereby preventing the exposed Cu powder from oxidizing. In addition, the inorganic coating structure with the above mass ratio will not have a negative impact on the conductivity of the Cu powder, so the conductor performance of the inorganic coated copper powder can be improved.

[0040] The Cu powder with the inorganic coating structure has a relatively complete and uniform inorganic coating layer, so that the anti-oxidation performance of the Cu powder can be improved without significantly losing the conductivity of the Cu powder. Specifically, the inorganic coating structure can cover at least 50% of the surface area of ​​the Cu core, and the coating structure thickness can be at the level of 10-100nn. In addition, the TGA curve of the Cu powder with the inorganic coating structure has no significant weight loss peak below 200°C, so its anti-oxidation performance is significantly enhanced.

[0041] In the present application, the area of ​​the surface of the Cu core covered by the inorganic coating structure can be obtained by scanning electron microscope photos of Cu powder and statistics using graphics processing software.

[0042] In another aspect of the present application, the present application provides a method for preparing the inorganic coated copper powder described above. Figure 1 The method comprises: adding a dispersing additive to a solvent, and adding an organic silicon source and an organic boron source to obtain SiO 2 -B 2 O 3 Sol; in the SiO 2 -B2 O 3 Cu powder is added to the sol, stirred and mixed, and then allowed to stand for 2-10 hours, and dried under inert atmosphere protection at a temperature of 150-250°C. This method is conducive to quickly and easily obtaining SiO 2 -B 2 O 3 Sol, improve the uniformity of the formed inorganic coating, and thus easily obtain high-quality inorganic coated copper powder.

[0043] In the method proposed in the present application, the dispersing additive is first added to the solvent, and then slowly added by dripping or pumping with a peristaltic pump to form SiO 2 -B 2 O 3 The raw materials of the sol, such as the organosilicon source and the organoboron source. Since the aforementioned amphiphilic dispersant already exists in the solution, when the organosilicon source begins to hydrolyze, the small crystal nuclei formed can be more evenly dispersed in the system, avoiding the accumulation of crystal nuclei to form large particles, thereby controlling the particle size distribution of the obtained silica to be narrower. On this basis, the organoboron source added later can also be hydrolyzed and reacted in a system with better dispersibility, thereby obtaining SiO2 with a narrower particle size distribution. 2 -B 2 O 3 Sol.

[0044] The inventors found that the SiO 2 -B 2 O 3 The sol has good coating performance, which can avoid the need to strictly control the reaction conditions during the hydrolysis process, or to perform complex tests on the degree of hydrolysis to determine whether the hydrolysis reaction is fully carried out. In this system with good dispersion, as long as the organic silicon source and the organic boron source are allowed to react for a period of time under stirring conditions, SiO2 with a good coating structure can be obtained. 2 -B 2 O 3 Therefore, it is helpful to simplify the process of preparing the inorganic coated copper powder, so that it can be better promoted and applied.

[0045] According to the embodiments of the present application, SiO 2 -B 2 O 3 The sol can be obtained based on the following steps:

[0046] (1) adding the dispersing additive to an alcohol solution and adjusting the pH value to 8.5-10 with a NaOH solution;

[0047] (2) Add ethyl orthosilicate, stir and react for 10-30 minutes;

[0048] (3) Add tributyl borate, stir and react for 10-30 minutes.

[0049] Specifically, the alcohol solution can be a methanol solution, and the use of an aqueous NaOH solution to adjust the pH value is conducive to the introduction of a small amount of water into the system, thereby promoting the hydrolysis of ethyl orthosilicate, increasing the speed of subsequent polycondensation and polymerization, and also facilitating the full reaction of the raw materials. For example, the pH value can be adjusted to 9. In some embodiments, ethyl orthosilicate and tributyl borate can be added to the reaction solution by dropwise addition or pumping, and the raw materials can be added in a short time, such as within 10 minutes, and then reacted for 10-30 minutes, for example, 20 minutes, under stirring. In order to SiO 2 and B 2 O 3 It can be further grown, or after stirring the reaction for 30 minutes, it can be left to stand for a period of time, such as 2-4 hours, and then fully hydrolyzed SiO 2 -B 2 O 3 Sol.

[0050] According to the embodiment of the present application, the Cu core body can be made of Cu powder prepared by the aforementioned condensation evaporation method. 2 -B 2 O 3 Before being added to the sol, the Cu powder may be pre-treated with pickling and immersion to remove dirt and dust on the surface of the Cu powder, and to appropriately remove the oxide layer on the surface of the Cu powder. In some embodiments, the surface of the Cu powder prepared by the condensation evaporation method may have a thinner oxide layer. Usually, the thickness of the oxide layer may be more than ten microns, and the main components of the oxide layer may be CuO, Cu (OH) 2 The oxide layer is formed in the process of preparing Cu powder by condensation evaporation method, or it can be formed in the later storage process due to oxidation of Cu powder surface. 2 -B 2 O 3 Before sol mixing, the oxide layer can be removed by pickling treatment, and then the inorganic coating structure can be formed, so as to improve the electrical properties of the obtained coated copper powder. Moreover, coating at a fresh interface is also conducive to improving the coating quality.

[0051] In some specific embodiments, the pickling can be performed using hydrochloric acid, for example, using dilute hydrochloric acid to pickle the Cu powder. The Cu powder after pickling can remove most of the oxidized substances and surface dust and impurities. Subsequently, in order to improve the SiO 2 -B 2 O 3The compatibility of the sol can be achieved by using formaldehyde solution to wet the acid-washed Cu powder.

[0052] The inorganic coating structure can be obtained by mixing Cu powder and the SiO 2 -B 2 O 3 Specifically, the Cu powder and the SiO sol can be mechanically mixed at 200-400 rpm. 2 -B 2 O 3 The sol is stirred and mixed. The mixed system can be left to stand for 4-6 hours to allow SiO 2 -B 2 O 3 Through physical adsorption and further growth of inorganic crystal nuclei, the mixture is evenly coated on the surface of Cu powder. After standing, the mixture can be dried under the protection of an inert atmosphere at a temperature of 150-250°C to remove the remaining solvent, and the obtained powder is the inorganic coated copper powder.

[0053] The Cu powder prepared by the method has a relatively complete and uniform inorganic coating layer, thereby improving the oxidation resistance of the Cu powder without significantly losing the electrical conductivity of the Cu powder.

[0054] In another aspect of the present application, the present application proposes a composition for preparing a conductive paste. The composition includes: conductive metal powder, a binder, a solvent, and an additive. The conductive metal powder is the inorganic coated copper powder described above. The binder includes at least one of a polyimide compound and an acrylate compound, the solvent includes at least one selected from a diol compound, a polyether compound, and a silanol compound, and the additive includes at least one of a tackifier, a leveling agent, a defoamer, and a coupling agent. The mass percentage of the conductive metal powder is 80-85%, and the mass ratio of the binder, the solvent, and the additive is: (7-10): (6-8): (2-6). The conductive paste prepared by the composition can form a coating with high conductivity, which is suitable for conductive bonding in the field of microelectronics.

[0055] According to an embodiment of the present application, the binder includes polyurethane-modified acrylate, the solvent includes diol, and the additive includes at least a tackifier and a coupling agent, thereby further improving the quality of the formed conductive paste.

[0056] According to an embodiment of the present application, based on the total mass of the composition, the composition includes: 80%-85% of the conductive metal powder, 6%-9% of the binder, 5%-7% of the solvent, 1%-3% of the tackifier, and 1%-2% of the coupling agent. This is conducive to further improving the quality of the formed conductive paste.

[0057] For example, the slurry may include at least 80 wt% of the aforementioned coated copper powder. Since the coated copper powder has better anti-oxidation ability, the slurry may have better conductivity after drying and sintering. Moreover, since the coating structure is relatively uniform, the conductive metal powder in the formed conductive slurry may be better dispersed in the resin binder, thereby forming a more continuous and reliable conductive film.

[0058] Specifically, the slurry may be composed of 82% conductive metal powder, 9% polyurethane modified acrylate, 7% dibenzyl ether, 1% KH550 coupling agent, and 1% propylene glycol monomethyl ether acetate for adjusting the slurry viscosity to improve the processability of the slurry.

[0059] The slurry can be prepared by uniformly mixing polyurethane modified acrylate, dibenzyl ether, KH550 coupling agent and propylene glycol monomethyl ether acetate, and then adding conductive metal powder for further mixing. The slurry can be cured at 150-180° C. to obtain a conductive film layer.

[0060] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0061] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0062] Example 1 Preparation of Coated Copper Powder

[0063] A dispersant shown in Formula 1 was used, wherein R is H, a=20, and all R1 are hydroxyl groups. 1wt% of the dispersant was added to a methanol solution, and 1mol / L NaOH was used to adjust the pH to 9. After mixing, tetraethyl orthosilicate was added dropwise under stirring conditions, and the addition was completed within 5 minutes. After reacting for 25 minutes, tributyl borate was added dropwise, and the addition was completed within 5 minutes. After reacting for 25 minutes, SiO 2 -B 2 O 3 Sol.

[0064] The Cu powder is a spherical powder with a Dv50 of 1 μm. The Cu powder is acid-washed three times with 0.5 mol / L HCL, washed with deionized water, immersed in a formaldehyde solution for 10 minutes, and dried for 30 minutes in an inert atmosphere for use.

[0065] Add dry Cu powder to SiO 2 -B 2 O 3 In the sol, the mass ratio of Cu powder to sol is 88:12. Stir and mix at 400 rpm until there is no obvious powder in the system, let it stand for 4 hours, and dry at 200 degrees Celsius to remove the residual solvent in the sol.

[0066] Example 2 Preparation of Coated Copper Powder

[0067] The remaining operations were the same as in Example 1, except that the amount of dispersant added was 3 wt %.

[0068] Example 3 Preparation of Coated Copper Powder

[0069] The remaining operations are the same as those in Example 1, except that the mass ratio of Cu powder to sol is 89:11.

[0070] Example 4 Preparation of Coated Copper Powder

[0071] The remaining operations are the same as those in Example 1, except that the mass ratio of Cu powder to sol is 86:14.

[0072] Example 5 Preparation of Coated Copper Powder

[0073] The remaining operations are the same as those in Example 1, except that the Cu powder used is a powder with a Dv50 of 500 nm.

[0074] Example 6 Preparation of Conductive Paste

[0075] The coated copper powder prepared in Example 1 is a conductive metal powder, and a slurry is prepared according to the following formula:

[0076] 82% conductive metal powder, 9% polyurethane modified acrylate, 7% dibenzyl ether, 1% KH550 coupling agent, and 1% propylene glycol monomethyl ether acetate.

[0077] Example 7 Preparation of Conductive Paste

[0078] The remaining operations are the same as those in Example 6, except that the coated copper powder prepared in Example 4 is a conductive metal powder.

[0079] Example 8 Preparation of Conductive Paste

[0080] The remaining operations are the same as those in Example 4, except that the slurry is prepared according to the following formula:

[0081] 80% conductive metal powder, 9% polyurethane modified acrylate, 7% dibenzyl ether, 2% KH550 coupling agent, and 2% propylene glycol monomethyl ether acetate.

[0082] Example 9 Preparation of Conductive Paste

[0083] The remaining operations are the same as those in Example 4, except that the slurry is prepared according to the following formula:

[0084] 85% conductive metal powder, 9% polyurethane modified acrylate, 5% dibenzyl ether, 1% KH550 coupling agent, and 1% propylene glycol monomethyl ether acetate.

[0085] Comparative Example 1

[0086] The coated copper powder was prepared according to the method of Example 4, except that the mass ratio of Cu powder to sol was 80:20. The conductive paste formula was the same as that of Example 6.

[0087] Comparative Example 2

[0088] The coated copper powder was prepared according to the method of Example 4, except that the mass ratio of Cu powder to sol was 90:10. The conductive paste formula was the same as that of Example 6.

[0089] Comparative Example 3

[0090] The coated copper powder was prepared according to the method of Example 4, except that no dispersant was added to the methanol solution. The conductive paste formula was the same as that of Example 6.

[0091] Comparative Example 4

[0092] The coated copper powder was prepared according to the method of Example 4, except that sodium hexametaphosphate was used as the dispersant and the conductive slurry formula was the same as that of Example 6.

[0093] Comparative Example 5

[0094] The coated copper powder was prepared according to the method of Example 4. The formula of the conductive slurry was the same as that of Example 6, except that the slurry used the following formula:

[0095] 75% conductive metal powder, 10% polyurethane modified acrylate, 10% dibenzyl ether, 2.5% KH550 coupling agent, and 2.5% propylene glycol monomethyl ether acetate.

[0096] Comparative Example 6

[0097] The remaining operations are the same as those in Comparative Example 5, except that the slurry adopts the following formula:

[0098] 88% conductive metal powder, 5% polyurethane modified acrylate, 5% dibenzyl ether, 1% KH550 coupling agent, and 1% propylene glycol monomethyl ether acetate.

[0099] The performance of the samples prepared in the above embodiments and comparative examples was tested. The particle size of the coated copper powder was tested using a laser particle size analyzer to obtain the Dv50 of the sample. The conductive slurry was coated on a PET base film and dried at 160 degrees Celsius. After drying, the dry film thickness was 10 μm and the resistivity of the film layer was measured.

[0100] Some test results of the above examples and comparative examples are shown in Table 1 below:

[0101] Table 1

[0102]

[0103] As can be seen from Table 1, the samples prepared in the examples of the present application have good electrical conductivity, proving that the electrical conductivity of the Cu powder and the conductive paste is well maintained on the basis of improving the antioxidant properties. Among them, the dispersant used in the present application has a better dispersing effect than the commonly used sodium hexametaphosphate, so the obtained powder Dv50 is moderate, the coating structure thickness is reasonable, and the conductivity is also better. In addition, the inorganic coated copper powder and the conductive paste have an appropriate proportion of metal, and the obtained conductive film layer has better electrical conductivity.

[0104] 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. An inorganic coated copper powder, characterized in that: It comprises a Cu core body and an inorganic coating structure coated on the surface of the Cu core body, wherein the inorganic coating structure comprises a SiO2-B2O3 compound, The Cu core body is spherical, and the particle size of the Cu core body is 0.1-3 μm. The area of ​​the Cu core covered by the inorganic coating structure is not less than 50% of the surface area of ​​the Cu core. The mass ratio of the inorganic coating structure to the Cu core is (11-14): (86-89); The inorganic coating structure further includes a dispersing additive, which includes an amphiphilic molecule containing silane and / or silanol. The dispersing additive is pre-added to the reaction solution before forming the SiO2-B2O3 compound, and the SiO2-B2O3 compound is coated on the surface of the Cu core by mechanical mixing.

2. The inorganic coated copper powder according to claim 1, characterized in that: The dispersing additive includes a compound represented by the following formula (1): Formula (1), Wherein, R is H, methyl, ethyl or COCH3, a=1-50, and R1 is methyl, ethyl, methoxy or hydroxyl.

3. The inorganic coated copper powder according to claim 1 or 2, characterized in that: The mass ratio of the SiO2-B2O3 compound in the inorganic coating structure to the dispersing additive is 95:5 to 99:

1.

4. A method for preparing the inorganic coated copper powder according to any one of claims 1 to 3, characterized in that: include: Adding a dispersing additive, an organic silicon source and an organic boron source into a solvent to obtain a SiO2-B2O3 sol; Cu powder is added to the SiO2-B2O3 sol, and the mixture is stirred and then allowed to stand for 2-10 hours, and then dried under the protection of an inert atmosphere at a temperature of 150-250°C.

5. The method according to claim 4, characterized in that The method for obtaining the SiO2-B2O3 sol comprises: (1) adding the dispersing additive to an alcohol solution and adjusting the pH value to 8.5-10 with a NaOH solution; (2) Add ethyl orthosilicate, stir and react for 10-30 minutes; (3) Add tributyl borate, stir and react for 10-30 minutes.

6. The method according to claim 5, characterized in that Before the Cu powder is added to the SiO2-B2O3 sol, it is pre-treated by pickling and infiltration. The Cu powder and the SiO2-B2O3 sol are stirred and mixed at 200-400 rpm and allowed to stand for 4-6 hours. The pickling is performed using hydrochloric acid, and the impregnation treatment is performed using formaldehyde.

7. A composition for preparing a conductive paste, characterized in that: include: Conductive metal powder, wherein the conductive metal powder is the inorganic coated copper powder according to any one of claims 1 to 3; A binder, wherein the binder includes at least one of a polyimide compound and an acrylate compound; A solvent, wherein the solvent comprises at least one selected from the group consisting of a diol compound, a polyether compound, and a silanol compound; The additive comprises at least one of a tackifier, a leveling agent, a defoamer and a coupling agent, wherein: The mass percentage of the conductive metal powder is 80-85%, The mass ratio of the binder, the solvent and the additive is: (7-10): (6-8): (2-6).

8. The composition according to claim 7, characterized in that The adhesive includes polyurethane modified acrylate, the solvent includes diol, and the additive includes at least a tackifier and a coupling agent.

9. The composition according to claim 8, characterized in that Based on the total mass of the composition, the composition comprises: 80%-85% of the conductive metal powder, 6%-9% of the binder, 5%-7% of the solvent, 1%-3% of the tackifier and 1%-2% of the coupling agent.

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