Preparation method of high-conductivity low-temperature sintered silver paste

Abstract

The invention discloses a preparation method of high-conductivity low-temperature sintered silver paste, which comprises the following steps: sequentially mixing organic silicon resin, a thickening agent, a thixotropic agent, a flatting agent, a defoaming agent and a silane coupling agent with an organic solvent, fully preheating at 50 DEG C, and uniformly stirring; then silver powder is added twice, the micron-sized flake silver powder is added for the first time, the silver nanoparticles are added for the second time, and uniform stirring is performed to obtain premixed slurry; and grinding the premixed paste for multiple times by using a mortar to obtain the finished silver paste. According to the silver paste and the preparation method thereof, the micron-sized flaky silver powder and the silver nanoparticles are mixed to jointly serve as a conductive phase, and the silver nanoparticles with relatively small particle sizes are used for filling pores among the flaky silver powder with relatively large particle sizes, so that a surface film layer of the prepared silver paste is more compact after printing and sintering, and the conductivity is improved. And meanwhile, through the synergistic effect between the flaky silver powder and the silver nanoparticles, the bending resistance of the sintered silver paste is improved.

Description

Technical Field

[0001] The present invention relates to the field of flexible electronic printing, and in particular to a method for preparing a high-conductivity, low-temperature sintering silver paste. Background Art

[0002] In recent years, with the rapid development of electronic information technology, the demand for silver paste has become increasingly greater. Low-temperature silver paste has been widely used in transparent conductive films, printed thin-film transistors, biosensors, radio frequency identification antennas, and emerging stretchable and wearable devices. However, my country's research on low-temperature silver paste is still lacking, and most products still rely on imports. Therefore, it is very necessary to develop low-temperature silver paste with excellent performance. Summary of the Invention

[0003] The purpose of the present invention is to develop a high-conductivity, low-temperature sintering silver paste with independent intellectual property rights, excellent printing performance, low production cost, simple preparation, dense film formation after low-temperature sintering, good conductivity, strong adhesion, excellent bending resistance, and stable storage to meet the needs of industrial production.

[0004] The present invention is achieved through the following technical solutions:

[0005] A high-conductivity, low-temperature sintering silver paste is composed of the following components in weight percentage: 80% to 84% silver powder, 4% to 7% resin, 9% to 13% solvent, and 1% to 2% additive; wherein,

[0006] The silver powder is composed of the following components: (1) micron-sized flaky silver powder, and (2) silver nanoparticles; wherein the micron-sized flaky silver powder accounts for 42% to 70%, and the silver nanoparticles account for 14% to 42%.

[0007] Furthermore, the particle size D50 of the micron-sized flaky silver powder is 2 to 5 μm.

[0008] Furthermore, the particle size D50 of the silver nanoparticles is 300-400 nm.

[0009] Furthermore, the resin is selected from a silicone resin.

[0010] Furthermore, the organic solvent is selected from dibasic acid ester (DBE).

[0011] Furthermore, the auxiliary agent is selected from one or more of a thixotropic agent, a thickener, a leveling agent, a defoaming agent, and a silane coupling agent.

[0012] Furthermore, the thixotropic agent is selected from polyamide wax.

[0013] Furthermore, the thickener is selected from ethyl cellulose.

[0014] Furthermore, the leveling agent is selected from BYK361N.

[0015] Furthermore, the defoaming agent is selected from Xiya reagent.

[0016] Furthermore, the silane coupling agent is selected from 3-glycidyloxypropyltrimethoxysilane.

[0017] Furthermore, during the mixing, the resin, solvent and additive are first mixed uniformly by mechanical stirring at 50° C., and then the silver powder is added twice in the order of adding: adding micron-sized flaky silver powder for the first time and adding silver nanoparticles for the second time, and stirring evenly to obtain a premixed slurry; the premixed slurry is ground multiple times using a mortar to ensure uniform dispersion.

[0018] The high-conductivity, low-temperature sintering silver paste of the present invention is prepared by mixing micron-sized flaky silver powder and silver nanoparticles as a conductive phase, and using smaller silver nanoparticles to fill the gaps between the larger flaky silver powders. This allows the surface film of the prepared silver paste to become denser after printing and sintering, thereby reducing the resistivity. The use of silicone resin as a bonding phase also improves the stability of the silver paste. At the same time, the silver electrode obtained after printing and sintering the silver paste has better bending resistance and electrical properties (better signal transmission capability). The high-conductivity, low-temperature sintering silver paste of the present invention has excellent printability, conductive properties and room temperature stability, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 The figure is a process flow chart for the preparation and printing of the high-conductivity, low-temperature sintering silver paste of the present invention;

[0021] Figure 2 The SEM morphology of the micron-sized flaky silver powder and silver nanoparticles in the present invention;

[0022] Figure 3 These are SEM morphologies of the surface film layers after silver paste printing and sintering in Example 2 and Comparative Example 2. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and Examples. However, the scope of the present invention is not limited to the following examples. Those skilled in the art will appreciate that various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention.

[0024] Unless otherwise specified, the instruments, reagents, and materials used in the following examples are all conventional instruments, reagents, and materials available in the prior art and can be obtained through regular commercial channels. The experimental methods and detection methods used in the following examples are all conventional experimental methods and detection methods available in the prior art, unless otherwise specified.

[0025] Application of the high-conductivity, low-temperature sintering silver paste in the field of flexible electronic printing.

[0026] Example 1 Preparation of high-conductivity low-temperature sintering silver paste

[0027] It is composed of the following components, calculated by weight percentage:

[0028] Micron-sized flake silver powder 66.7% (D50: 2-5 μm);

[0029] Silver nanoparticles 13.3% (D50: 300-400 nm);

[0030] Silicone resin 6%;

[0031] Organic solvent 11.2% (dibasic acid ester);

[0032] Thixotropic agent 0.6% (polyamide wax);

[0033] Thickener 0.6% (ethyl cellulose);

[0034] Leveling agent 0.3% (BYK361N);

[0035] Defoaming agent 0.3% (Siya reagent);

[0036] Silane coupling agent 1% (3-glycidyloxypropyltrimethoxysilane).

[0037] The preparation method is:

[0038] (1) Mixing: First, mix the silicone resin, thickener, thixotropic agent, leveling agent, defoaming agent and silane coupling agent with the solvent, stir evenly with a mechanical stirrer and fully preheat at 50 °C; then add silver powder twice, the order of addition is: first add micron-sized flake silver powder, and second add silver nanoparticles (the SEM morphology of the two silver powders is shown in the attached figure). Figure 2 ), stir evenly to obtain a premixed slurry;

[0039] (2) Grinding: The above premixed slurry is ground using a mortar and pestle, and the grinding is repeated multiple times to ensure uniform dispersion, thereby obtaining a high-conductivity, low-temperature sintering silver paste. (The preparation and subsequent printing and sintering process is shown in the attached Figure 1 )

[0040] Example 2 Preparation of high-conductivity low-temperature sintering silver paste

[0041] It is composed of the following components, calculated by weight percentage:

[0042] Micron-sized flake silver powder 64% (D50: 2-5 μm);

[0043] Silver nanoparticles 16% (D50: 300-400 nm);

[0044] Silicone resin 6%;

[0045] Organic solvent 11.2% (dibasic acid ester);

[0046] Thixotropic agent 0.6% (polyamide wax);

[0047] Thickener 0.6% (ethyl cellulose);

[0048] Leveling agent 0.3% (BYK361N);

[0049] Defoaming agent 0.3% (Siya reagent);

[0050] Silane coupling agent 1% (3-glycidyloxypropyltrimethoxysilane). The preparation process is the same as in Example 1.

[0051] Example 3 Preparation of High Conductivity Low Temperature Sintering Silver Paste

[0052] It is composed of the following components, calculated by weight percentage:

[0053] 60% micron-sized flake silver powder (D50: 2-5 μm);

[0054] Silver nanoparticles 20% (D50: 300-400 nm);

[0055] Silicone resin 6%;

[0056] Organic solvent 11.2% (dibasic acid ester);

[0057] Thixotropic agent 0.6% (polyamide wax);

[0058] Thickener 0.6% (ethyl cellulose);

[0059] Leveling agent 0.3% (BYK361N);

[0060] Defoaming agent 0.3% (Siya reagent);

[0061] Silane coupling agent 1% (3-glycidyloxypropyltrimethoxysilane). The preparation process is the same as in Example 1.

[0062] Example 4 Preparation of High Conductivity Low Temperature Sintering Silver Paste

[0063] It is composed of the following components, calculated by weight percentage:

[0064] 53.3% micron-sized flake silver powder (D50: 2-5 μm);

[0065] Silver nanoparticles 26.7% (D50: 300-400 nm);

[0066] Silicone resin 6%;

[0067] Organic solvent 11.2% (dibasic acid ester);

[0068] Thixotropic agent 0.6% (polyamide wax);

[0069] Thickener 0.6% (ethyl cellulose);

[0070] Leveling agent 0.3% (BYK361N);

[0071] Defoaming agent 0.3% (Siya reagent);

[0072] Silane coupling agent 1% (3-glycidyloxypropyltrimethoxysilane). The preparation process is the same as in Example 1.

[0073] Example 5 Preparation of high-conductivity low-temperature sintering silver paste

[0074] It is composed of the following components, calculated by weight percentage:

[0075] 40% micron-sized flake silver powder (D50: 2-5 μm);

[0076] Silver nanoparticles 40% (D50: 300-400 nm);

[0077] Silicone resin 6%;

[0078] Organic solvent 11.2% (dibasic acid ester);

[0079] Thixotropic agent 0.6% (polyamide wax);

[0080] Thickener 0.6% (ethyl cellulose);

[0081] Leveling agent 0.3% (BYK361N);

[0082] Defoaming agent 0.3% (Siya reagent);

[0083] Silane coupling agent 1% (3-glycidyloxypropyltrimethoxysilane).

[0084] The preparation process is the same as that of Example 1.

[0085] Comparative Example 1 Preparation of High Conductivity Low Temperature Sintering Silver Paste

[0086] It is composed of the following components, calculated by weight percentage:

[0087] 80% micron-sized flake silver powder (D50: 2-5 μm);

[0088] Silicone resin 6%;

[0089] Organic solvent 11.2% (dibasic acid ester);

[0090] Thixotropic agent 0.6% (polyamide wax);

[0091] Thickener 0.6% (ethyl cellulose);

[0092] Leveling agent 0.3% (BYK361N);

[0093] Defoaming agent 0.3% (Siya reagent);

[0094] Silane coupling agent 1% (3-glycidyloxypropyltrimethoxysilane).

[0095] The preparation process is the same as that of Example 1.

[0096] Comparative Example 2 Commercial Silver Paste

[0097] This silver paste was purchased directly from Suzhou Hongpai Technology Co., Ltd., and its specific composition ratio and preparation process are unknown.

[0098] The performance of the silver electrodes obtained after printing and sintering (230° C., 30 min) the silver pastes in Examples 1 to 5 and Comparative Examples 1-2 was tested. The test results are shown in Table 1.

[0099] Table 1 Resistivity and bending performance test data

[0100]

[0101] Combining Examples 1 to 5 with Comparative Example 1, it can be seen that after adding silver nanoparticles, the volume resistivity and bending resistance of the silver electrode are significantly improved. At the same time, with the increase of the content of silver nanoparticles, the volume resistivity of the silver electrode shows a trend of first decreasing and then increasing. In particular, when the contents of micron-sized flaky silver powder and silver nanoparticles in the silver paste are 64% and 16% respectively, that is, when the ratio of flaky silver powder to silver nanoparticles is 4:1, the prepared silver electrode has both low volume resistivity and good bending resistance. A performance comparison of the silver electrodes obtained after printing and sintering the silver paste in Example 2 and Comparative Example 2 found that the silver electrodes prepared by the present invention and commercial silver paste are already close in conductivity and bending resistance. Combining Figure 3 The SEM morphology of the surface films after sintering the two silver paste printings also shows that the surface films of both are very dense.

[0102] In summary, the present invention reduces resistivity by adding silver nanoparticles to micron-sized flaky silver powder. The use of a silicone resin system in the preparation process also improves the stability of the silver paste. The silver electrodes printed using this silver paste also exhibit improved bending resistance and electrical properties (better signal transmission capabilities). The highly conductive, low-temperature sintered silver paste of the present invention has excellent printability, electrical conductivity, and room-temperature stability, and has broad application prospects.

[0103] The foregoing description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed herein are intended to be encompassed within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a high-conductivity, low-temperature sintering silver paste, comprising the following components in percentage by weight: Silver powder 80% to 84%, resin 4% to 7%, organic solvent 9% to 13%, additive 1% to 2%; among which, The silver powder is composed of the following components: (1) micron-sized flaky silver powder, and (2) silver nanoparticles; the micron-sized flaky silver powder accounts for 42% to 70% of the silver paste, and the silver nanoparticles account for 14% to 42% of the silver paste.

2. The high-conductivity, low-temperature sintering silver paste according to claim 1, characterized in that: The silver powder includes micron-sized flaky silver powder and silver nanoparticles, the mixing ratio of the micron-sized flaky silver powder and the silver nanoparticles is 5:1 to 1:1, the particle size D50 of the flaky silver powder is 2 to 5 μm, and the particle size D50 of the silver nanoparticles is 300 to 400 nm.

3. The high-conductivity, low-temperature sintering silver paste according to claim 1, characterized in that: The resin is selected from a silicone resin.

4. The high-conductivity, low-temperature sintering silver paste according to claim 1, characterized in that: The organic solvent is selected from dibasic acid esters (DBE).

5. The high-conductivity, low-temperature sintering silver paste according to claim 1, characterized in that: The auxiliary agent is selected from one or more of a thixotropic agent, a thickener, a leveling agent, a defoaming agent, and a silane coupling agent.

6. The high-conductivity, low-temperature sintering silver paste according to claim 5, characterized in that: The leveling agent is selected from BYK361N; The thickener is selected from ethyl cellulose; The thixotropic agent is selected from polyamide wax; The defoaming agent is selected from the group consisting of West Asia reagent; The silane coupling agent is selected from 3-glycidyloxypropyltrimethoxysilane.

7. The method for preparing a high-conductivity, low-temperature sintering silver paste according to any one of claims 1 to 6, characterized in that: The components are stirred and mixed evenly to obtain a premixed slurry; the premixed slurry is ground several times to obtain a slurry, which is a high-conductivity, low-temperature sintering silver paste.

8. The method for preparing a high-conductivity, low-temperature sintering silver paste according to claim 7, wherein: During the mixing, the resin, organic solvent and additive are first mixed uniformly by mechanical stirring at 50° C., and then micron-sized flaky silver powder and silver nanoparticles are added in sequence and stirred uniformly to obtain a premixed slurry. Finally, the mixture is ground in a mortar for multiple times to ensure uniform dispersion.

9. Use of the high-conductivity, low-temperature sintering silver paste according to any one of claims 1 to 8 in the field of flexible electronic printing.

Images