Preparation method of modified micron gold dispersion liquid and conductive gold paste

Abstract

The application relates to a preparation method of modified micron gold dispersion liquid and conductive gold paste. Gold powder is prepared by an in-situ synthesis method, the gold powder is modified by CTAB, the gold is directly transferred into an organic solution by utilizing the different surface tension of the gold particles after surface modification in different solutions, the gold can be directly configured into a slurry, the gold powder can be uniformly dispersed in the slurry without needing to be precipitated, dried and re-dispersed, the problems of uneven dispersion of the gold powder and unstable performance after sintering caused by the precipitation and dispersion in the traditional process are avoided, meanwhile, the yield of the gold powder is higher, and new impurities are avoided in the drying step.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to a method for preparing a modified micron-sized gold dispersion and a conductive gold paste. Background Technology

[0002] Conductive pastes can generally be divided into two categories: polymer conductive pastes and sintered conductive pastes. Polymer conductive pastes are dried or cured into films, using organic polymers as the binder phase. Sintered conductive pastes are typically sintered at temperatures above 500℃, using glass powder or oxides as the binder phase. Due to their excellent conductivity, solderability, hot-press weldability, and corrosion resistance, sintered conductive pastes are widely used in the manufacture of electronic components such as capacitors and potentiometers, as well as electrical components such as high-voltage and high-frequency ceramic parts. They are functional and structural materials integrating chemical, metallurgical, and electronic technologies, and have attracted considerable attention in the electronic paste industry.

[0003] Existing methods for preparing conductive pastes typically involve first obtaining gold powder, then precipitating and drying the gold powder, and finally dispersing the gold powder in a solvent to prepare the gold paste. However, during the redispersion process, uneven dispersion of the gold powder in the paste can occur, leading to unstable performance after sintering. To address this issue, this invention proposes a method for preparing a modified micron-sized gold dispersion and a conductive gold paste. Summary of the Invention

[0004] To avoid uneven dispersion caused by the redispersion of gold powder after precipitation, this invention proposes a method for preparing modified micron gold dispersion and conductive gold paste. This method adopts an in-situ synthesis method, which allows the synthesized gold powder to be directly and uniformly dispersed in the solution without precipitation and drying steps. The prepared modified micron gold dispersion can then be used to directly prepare a conductive gold paste with uniform gold powder dispersion and stable performance after sintering.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for preparing a modified micron-sized gold dispersion, characterized by comprising the following steps:

[0006] S1. Mix and dissolve chloroauric acid solution and dispersant to obtain gold solution;

[0007] S2. Mix and dissolve the reducing agent solution and the dispersant to obtain a reduced dispersion;

[0008] S3. Add the reducing dispersion to the gold solution, adjust the pH of the mixed solution system to 3-4 to carry out the reduction reaction, and obtain the reducing solution;

[0009] S4. Add hexadecyltrimethylammonium bromide (CTAB) solution to the reducing solution and stir for 12-24 hours;

[0010] S5. Add a small amount of butyl carbitol acetate. After separation, take the upper layer to obtain a butyl carbitol acetate micronized gold dispersion, i.e., a modified micronized gold dispersion. Butyl carbitol acetate is added in appropriate amounts to extract micronized gold from the solution.

[0011] Furthermore, the dispersant includes sodium citrate.

[0012] Furthermore, the reducing agent includes either ascorbic acid or tannic acid.

[0013] Furthermore, the reduction reaction temperature of S3 is 60-100℃, and the time is 0.5-2h.

[0014] Further, in step S4, the mass ratio of CTAB solution to chloroauric acid in step S1 is CTAB solution:chloroauric acid = 1:(2-5), and the concentration of CTAB solution is 0.05-0.2 mol / L.

[0015] Furthermore, the particle size of the micron-sized gold powder is 1-3 μm.

[0016] The mass ratio of chloroauric acid, dispersant and reducing agent is 1:(0.3-0.5):(0.2-0.5).

[0017] As a general inventive concept, the present invention also provides a conductive gold paste comprising the following components in weight percentages:

[0018] Modified micron gold dispersion 70-90%,

[0019] Inorganic additives 0-5%,

[0020] Film-forming carrier 5-20%,

[0021] Additives 0-1%,

[0022] Solvent 2-10%;

[0023] Furthermore, the modified micron gold dispersion is prepared by the above-described preparation method.

[0024] Further, the inorganic additives in the conductive gold paste include the following components in percentage: 15-25% Al2O3, 25-35% SiO2, 15-25% Bi2O3, 10-20% SrCO3 and 10-20% CaCO3; more preferably, the inorganic additives include the following components in percentage: 20% Al2O3, 30% SiO2, 20% Bi2O3, 15% SrCO3 and 15% CaCO3.

[0025] The film-forming carrier is a cellulose resin emulsion;

[0026] The auxiliary agent is a silane coupling agent;

[0027] The solvent is any one or more of terpineol, diethylene glycol butyl ether, and butyl carbitol acetate.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This invention prepares gold powder through in-situ synthesis. The gold powder is modified using CTAB. By utilizing the different surface tensions of the surface-modified gold particles in different solutions, the gold is directly transferred to the organic solution and can be directly prepared into a slurry. The gold powder can be uniformly dispersed in the slurry without precipitation, drying, and redispersing. This avoids the problems of uneven gold powder dispersion and unstable performance after sintering caused by precipitation followed by dispersion in traditional processes. At the same time, it can increase the yield of gold powder and avoid the introduction of new impurities in the drying step. Attached Figure Description

[0030] Figure 1 The image is an image observed under a microscope with backlight after the conductive paste prepared in Example 1 was sintered.

[0031] Figure 2 This is an image of the conductive paste prepared in Comparative Example 1 after sintering, observed under a microscope with backlight. Detailed Implementation

[0032] The invention will be further illustrated in the following embodiments, but the invention is not limited thereto.

[0033] Example 1

[0034] A method for preparing a modified micron-sized gold dispersion according to the present invention includes the following steps:

[0035] S1. Mix and dissolve 10g of chloroauric acid solution and 3g of dispersant to obtain gold solution;

[0036] S2. Mix and dissolve 5g of reducing agent solution and 1g of dispersant to obtain a reducing dispersion;

[0037] S3. Add the reducing dispersion to the gold solution, adjust the pH of the mixed solution system to 3-4 with formic acid solution to carry out the reduction reaction, control the temperature at 80℃, and react for 1 hour to obtain the reducing solution;

[0038] S4. Add 2 g of 0.1 mol / L CTAB solution to the reducing solution and stir for 12 h;

[0039] S5. Add 3g of butyl carbitol acetate. After separation, take the upper butyl carbitol acetate portion to obtain a butyl carbitol acetate micron gold dispersion, i.e., a modified micron gold dispersion. The particle size of the micron gold powder in this modified micron gold dispersion is 1-3μm.

[0040] A conductive gold paste of the present invention comprises the following components in weight percentage:

[0041] The modified micron gold dispersion prepared in this embodiment has a content of 70%.

[0042] Inorganic additives 4%,

[0043] Film-forming carrier 20%,

[0044] 1% of the additives

[0045] Solvent 5%;

[0046] The inorganic additives consist of 20% Al2O3, 30% SiO2, 20% Bi2O3, 15% SrCO3 and 15% CaCO3.

[0047] The film-forming carrier is prepared by dissolving cellulose resin in a mixed solvent, wherein the mass ratio of cellulose resin to mixed solvent is 1:4; the mixed solvent contains terpineol and diethylene glycol butyl ether in a volume ratio of 4:6.

[0048] The additive is KH570 silane coupling agent;

[0049] The solvent is terpineol.

[0050] Example 2

[0051] A method for preparing a modified micron-sized gold dispersion according to the present invention includes the following steps:

[0052] S1. Mix and dissolve 10g of chloroauric acid solution and 4g of dispersant to obtain gold solution;

[0053] S2. Mix and dissolve 2g of reducing agent solution and 1g of dispersant to obtain a reducing dispersion;

[0054] S3. Add the reducing dispersion to the gold solution, adjust the pH of the mixed solution system to 3-4 with acetic acid solution to carry out the reduction reaction, control the temperature at 60℃, and react for 2 hours to obtain the reducing solution;

[0055] S4. Add 5g of 0.05mol / L CTAB solution to the reducing solution and stir for 12h;

[0056] S5. Add 3g of butyl carbitol acetate. After separation, take the upper butyl carbitol acetate portion to obtain a butyl carbitol acetate micron gold dispersion, i.e., a modified micron gold dispersion. The particle size of the micron gold powder in this modified micron gold dispersion is 1-3μm.

[0057] A conductive gold paste of the present invention comprises the following components in weight percentage:

[0058] The modified micron gold dispersion prepared in Example 2 has 80%...

[0059] Inorganic additives 4%,

[0060] 10% film-forming carrier

[0061] 1% of the additives

[0062] Solvent 5%;

[0063] The inorganic additives consist of 20% Al2O3, 30% SiO2, 20% Bi2O3, 15% SrCO3 and 15% CaCO3.

[0064] The film-forming carrier is prepared by dissolving cellulose resin in a mixed solvent, wherein the mass ratio of cellulose resin to mixed solvent is 1:4; the mixed solvent contains terpineol and diethylene glycol butyl ether in a volume ratio of 4:6.

[0065] The additive is KH570 silane coupling agent;

[0066] The solvent is terpineol.

[0067] Example 3

[0068] A method for preparing a modified micron-sized gold dispersion according to the present invention includes the following steps:

[0069] S1. Mix and dissolve 10g of chloroauric acid solution and 2g of dispersant to obtain gold solution;

[0070] S2. Mix and dissolve 4g of reducing agent solution and 1g of dispersant to obtain a reducing dispersion;

[0071] S3. Add the reducing dispersion to the gold solution, adjust the pH of the mixed solution system to 3-4 with acetic acid solution to carry out the reduction reaction, control the temperature at 100℃, and react for 0.5 hours to obtain the reducing solution;

[0072] S4. Add 2g of 0.2mol / L CTAB solution to the reducing solution and stir for 18h;

[0073] S5. Add 4g of butyl carbitol acetate. After separation, take the upper butyl carbitol acetate layer to obtain a butyl carbitol acetate micron gold dispersion, i.e., a modified micron gold dispersion. The particle size of the micron gold powder in this modified micron gold dispersion is 1-3μm.

[0074] A conductive gold paste of the present invention comprises the following components in weight percentage:

[0075] The modified micron gold dispersion prepared in Example 3 has 90%...

[0076] Inorganic additives 2%,

[0077] Film-forming carrier 5%,

[0078] 1% of the additives

[0079] Solvent 2%;

[0080] The inorganic additives consist of 20% Al2O3, 30% SiO2, 20% Bi2O3, 15% SrCO3 and 15% CaCO3.

[0081] The film-forming carrier is prepared by dissolving cellulose resin in a mixed solvent, wherein the mass ratio of cellulose resin to mixed solvent is 1:4; the mixed solvent contains terpineol and diethylene glycol butyl ether in a volume ratio of 4:6.

[0082] The additive is KH570 silane coupling agent;

[0083] The solvent is terpineol.

[0084] Example 4

[0085] A method for preparing a modified micron-sized gold dispersion according to the present invention includes the following steps:

[0086] S1. Mix and dissolve 10g of chloroauric acid solution and 2g of dispersant to obtain gold solution;

[0087] S2. Mix and dissolve 4g of reducing agent solution and 2g of dispersant to obtain a reducing dispersion;

[0088] S3. Add the reducing dispersion to the gold solution, adjust the pH of the mixed solution system to 3-4 with formic acid solution to carry out the reduction reaction, control the temperature at 70℃, and react for 1.5 hours to obtain the reducing solution;

[0089] S4. Add 3g of 0.1mol / L CTAB solution to the reducing solution and stir for 24h;

[0090] S5. Add 4g of butyl carbitol acetate. After separation, take the upper butyl carbitol acetate layer to obtain a butyl carbitol acetate micron gold dispersion, i.e., a modified micron gold dispersion. The particle size of the micron gold powder in this modified micron gold dispersion is 1-3μm.

[0091] A conductive gold paste of the present invention comprises the following components in weight percentage:

[0092] The modified micron gold dispersion prepared in this embodiment has a content of 85%.

[0093] Inorganic additives 1%,

[0094] Film-forming carrier 5%,

[0095] 1% of the additives

[0096] Solvent 8%;

[0097] The inorganic additives consist of 20% Al2O3, 30% SiO2, 20% Bi2O3, 15% SrCO3 and 15% CaCO3.

[0098] The film-forming carrier is prepared by dissolving cellulose resin in a mixed solvent, wherein the mass ratio of cellulose resin to mixed solvent is 1:4; the mixed solvent contains terpineol and diethylene glycol butyl ether in a volume ratio of 4:6.

[0099] The additive is KH570 silane coupling agent;

[0100] The solvent is terpineol.

[0101] Comparative Example 1

[0102] A conductive gold paste comprising the following components in weight percentages:

[0103] 80% gold per micrometer

[0104] Inorganic additives 1%,

[0105] Film-forming carrier 5%,

[0106] 1% of the additives

[0107] Solvent 13%;

[0108] The inorganic additives consist of 20% Al2O3, 30% SiO2, 20% Bi2O3, 15% SrCO3 and 15% CaCO3.

[0109] The film-forming carrier is prepared by dissolving cellulose resin in a mixed solvent, wherein the mass ratio of cellulose resin to mixed solvent is 1:4; the mixed solvent contains terpineol and diethylene glycol butyl ether in a volume ratio of 4:6.

[0110] The additive is KH570 silane coupling agent;

[0111] The solvent is terpineol.

[0112] Comparative Example 2

[0113] A conductive gold paste comprising the following components in weight percentages:

[0114] 70% gold per micrometer

[0115] Inorganic additives 3%,

[0116] Film-forming carrier 11%,

[0117] 1% of the additives

[0118] Solvent 15%;

[0119] The inorganic additives consist of 20% Al2O3, 30% SiO2, 20% Bi2O3, 15% SrCO3 and 15% CaCO3.

[0120] The film-forming carrier is prepared by dissolving cellulose resin in a mixed solvent, wherein the mass ratio of cellulose resin to mixed solvent is 1:4; the mixed solvent contains terpineol and diethylene glycol butyl ether in a volume ratio of 4:6.

[0121] The additive is KH570 silane coupling agent;

[0122] The solvent is terpineol.

[0123] The preparation method of the micron-sized gold in Comparative Examples 1-2 is as follows:

[0124] 10g of chloroauric acid solution and 2g of dispersant were mixed and dissolved to obtain gold solution; 4g of reducing agent solution and 2g of dispersant were mixed and dissolved to obtain reducing dispersion.

[0125] The reducing dispersion was added to the gold solution, and the pH of the mixed solution system was adjusted to 3-4 with formic acid solution to carry out the reduction reaction. The temperature was controlled at 70°C and the reaction was carried out for 1.5 hours to obtain the reducing solution. After precipitation, washing and drying, micron-sized gold was obtained.

[0126] The conductive gold pastes prepared in Examples 1-4 and Comparative Examples 1-2 were tested for performance according to GB / T 17473.3-2008, and the resistance values ​​are shown in Table 1.

[0127] Table 1. Test performance of conductive gold pastes prepared in Examples 1-4 and Comparative Examples 1-2

[0128]

[0129] As can be seen from Table 1, the conductive gold paste prepared by the present invention has a low sheet resistance and better conductivity. Furthermore, using the method of Example 4, the conductive gold paste was prepared in multiple batches, with a sheet resistance difference of ±5% between batches, indicating good batch stability. In contrast, the conductive gold paste prepared by the general method (Comparative Example 1) had a sheet resistance difference of ±15% between batches, and the quality difference between different batches was much greater than that of the present invention.

[0130] The slurries prepared in Example 1 and Comparative Example 1 were sintered and observed under a microscope, and photographs were taken. Figure 1 and Figure 2 It can be seen that the gold paste prepared by the method provided by the present invention has significantly higher sintering density.

Claims

1. A method for preparing a modified micron-sized gold dispersion, characterized in that, Includes the following steps: S1. Mix and dissolve chloroauric acid solution and dispersant to obtain gold solution; S2. Mix and dissolve the reducing agent solution and the dispersant to obtain a reduced dispersion; S3. Add the reducing dispersion to the gold solution, adjust the pH of the mixed solution system to 3-4 to carry out the reduction reaction, and obtain the reducing solution; S4. Add hexadecyltrimethylammonium bromide solution to the reducing solution, stir, and carry out the modification reaction; the mass ratio of hexadecyltrimethylammonium bromide solution to chloroauric acid in step S1 is hexadecyltrimethylammonium bromide solution: chloroauric acid = 1: (2-5), and the concentration of hexadecyltrimethylammonium bromide solution is 0.05-0.2 mol / L; S5. Add butyl carbitol acetate to the reducing solution, and after separation, take the upper layer solution to obtain butyl carbitol acetate micron gold dispersion, i.e. the modified micron gold dispersion. The mass ratio of chloroauric acid, dispersant and reducing agent is 1:(0.3-0.5):(0.2-0.5).

2. The method for preparing the modified micron gold dispersion according to claim 1, characterized in that, The dispersant includes sodium citrate.

3. The method for preparing the modified micron-sized gold dispersion according to claim 1, characterized in that, The reducing agent includes either ascorbic acid or tannic acid.

4. The method for preparing the modified micron gold dispersion according to claim 1, characterized in that, The reduction reaction temperature in step S3 is 60-100℃, and the time is 0.5-2h.

5. The method for preparing the modified micron gold dispersion according to claim 1, characterized in that, The particle size of the gold powder in the modified gold dispersion is 1-3 μm.

6. A conductive gold paste, characterized in that, Components including the following mass percentages: Modified micron gold dispersion 70-90%, Inorganic additives 0-5%, Film-forming carrier 5-20%, Additives 0-1%, Solvent 2-10%; The modified micron gold dispersion is prepared by the preparation method according to any one of claims 1-5.

7. The conductive gold paste according to claim 6, wherein the inorganic additive comprises the following components in percentage: 15-25% Al2O3, 25-35% SiO2, 15-25% Bi2O3, 10-20% SrCO3 and 10-20% CaCO3.

8. The conductive gold paste according to claim 6 or 7, characterized in that, The film-forming carrier is a cellulose resin emulsion; The auxiliary agent is a silane coupling agent; The solvent is any one or more of terpineol, diethylene glycol butyl ether, and butyl carbitol acetate.

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