A conductive silver paste, its preparation method and application

Abstract

This invention relates to a conductive silver paste, its preparation method, and its application. The conductive silver paste comprises silver powder, glass powder, an organic carrier, a thixotropic agent, and a dispersant. The organic carrier includes resin and a solvent; the resin is ethyl cellulose and acrylic resin, and the thixotropic agent is fumed silica and hydrogenated castor oil. This invention uses low molecular weight ethyl cellulose and acrylic resin to reduce the viscosity of the organic carrier, enhance the fluidity of the paste, and improve screen printing capability. Simultaneously, the hydrophobic fumed silica used as a thixotropic agent forms hydrogen bonds between the silanol groups on its surface and between the silanol groups and resin molecules, which can construct a three-dimensional network structure and improve anti-settling ability. The hydrogenated castor oil forms tiny whiskers in the organic solvent, which intertwine to form a network structure, facilitating the recovery of the paste's morphology after shearing and exhibiting good plasticity. This invention can effectively improve the screen printing performance of conductive silver paste, thereby effectively improving the aspect ratio of the electrodes.

Description

Technical Field

[0001] This invention relates to the field of solar cell paste technology, specifically to a conductive silver paste, its preparation method, and its application. Background Technology

[0002] Currently, photovoltaic silicon-based cells use screen printing to fabricate electrodes. For improving the efficiency of silicon-based solar cells, the preparation of electrodes with excellent aspect ratios has become an effective method. Firstly, finer grid lines (the "narrow" in aspect ratio) reduce the shading area on the cell's light-receiving surface, allowing more sunlight to reach the silicon wafer, thereby exciting more photogenerated carriers, increasing the short-circuit current (Isc), and directly increasing the "source" of power generation. Secondly, taller grid lines (the "high" in aspect ratio) mean a larger cross-sectional area of ​​the conductive metal. According to the resistance law R=ρL / A, the larger the cross-sectional area A, the smaller the resistance R. Finally, the solder joints are stronger, better able to withstand the thermal stress during module lamination and the mechanical stress during operation, greatly reducing the risk of cell interconnect breakage (grid breakage) and poor soldering, improving the long-term reliability of the module. In short, electrodes with excellent aspect ratios are key to achieving high conversion efficiency in silicon-based solar cells. Therefore, this requires the conductive silver paste for solar cells to have good screen printability.

[0003] However, existing conductive silver pastes cannot maintain stable viscosity and have poor screen passing ability during continuous and long-term printing, and the printed lines have poor plasticity, making it impossible to prepare electrodes with high aspect ratios. Summary of the Invention

[0004] The purpose of this invention is to provide a conductive silver paste, its preparation method, and its application. This conductive silver paste has good screen printability and can improve the aspect ratio of the printed electrodes.

[0005] To achieve the above objectives, the first aspect of the present invention provides a conductive silver paste, the conductive silver paste comprising: silver powder, glass powder, organic carrier, thixotropic agent, and dispersant; wherein the mass ratio of the silver powder, the glass powder, the organic carrier, the thixotropic agent, and the dispersant is 80-90:2-5:8-15:2-5:1; The organic carrier comprises 10-20 parts of resin and 80-90 parts of solvent by weight. The resin is ethyl cellulose and acrylic resin, wherein the molecular weight of the ethyl cellulose is 4-80 mPa·s; The thixotropic agent is fumed silica and hydrogenated castor oil.

[0006] Optionally, the silver powder has a D50 particle size of 1.0-1.5 μm and a tap density of 3-5 g / cm³. 3 .

[0007] Optionally, the glass powder has a D50 particle size of 0.5-2 μm and a Tg point of 400-500℃.

[0008] Optionally, the glass powder comprises 50-80 parts by weight of Pb3O4, 10-30 parts by weight of SiO2, and the balance being ZnO.

[0009] Optionally, the mass ratio of the fumed silica to the hydrogenated castor oil is 1-5:1.

[0010] Optionally, the solvent is one or more of alcohol ester dodecyl, alcohol ester hexadecyl, and butyl carbitol; the dispersant is one or more of methacrylic acid, alkylphenol polyoxyethylene ether, and fatty acid polyoxyethylene ether.

[0011] A second aspect of the present invention provides a method for preparing the conductive silver paste provided in the first aspect of the present invention, the method comprising: Ethyl cellulose, acrylic resin and solvent are mixed and stirred for the first time to obtain a uniform and transparent organic carrier; After mixing the silver powder and glass powder, a second stirring is performed to obtain a uniformly dispersed mixture. The mixture, the organic carrier, the thixotropic agent, and the dispersant are mixed and then subjected to a first centrifugal dispersion, followed by grinding and dispersion in a three-roll mill to obtain a dispersed material. The dispersed material is then subjected to a second centrifugal dispersion.

[0012] Optionally, the first stirring temperature is 50-80℃, and the time is 3-6h.

[0013] Optionally, the first centrifugal dispersion speed and the second centrifugal dispersion speed are each independently 4000-5000 rpm.

[0014] Optionally, the fineness of the dispersed material is less than 10 μm.

[0015] A third aspect of the present invention provides a silicon solar cell, wherein the silicon solar cell uses the conductive silver paste provided in the first aspect of the present invention.

[0016] Through the above technical solutions, this invention utilizes low molecular weight ethyl cellulose and acrylic resin to reduce the viscosity of the organic carrier and enhance the fluidity of the paste. During continuous and long-term printing, the paste maintains stable viscosity and high screen-passing capability. Simultaneously, the thixotropic hydrophobic fumed silica used forms hydrogen bonds between the silanol groups on its surface and between the silanol groups and resin molecules, constructing a three-dimensional network structure and improving anti-settling ability. Hydrogenated castor oil forms tiny whiskers in organic solvents, which intertwine to form a network structure, facilitating the restoration of the paste's morphology after shearing and exhibiting excellent plasticity. This invention effectively improves the screen printing performance of conductive silver paste through the above methods, thereby effectively increasing the aspect ratio of the electrodes.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0018] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0019] The first aspect of the present invention provides a conductive silver paste, the conductive silver paste comprising: silver powder, glass powder, organic carrier, thixotropic agent, and dispersant; wherein the mass ratio of the silver powder, the glass powder, the organic carrier, the thixotropic agent, and the dispersant is 80-90:2-5:8-15:2-5:1; The organic carrier comprises 10-20 parts of resin and 80-90 parts of solvent by weight. The resin is ethyl cellulose and acrylic resin, wherein the molecular weight of the ethyl cellulose is 4-80 mPa·s; The thixotropic agent is fumed silica and hydrogenated castor oil.

[0020] According to the present invention, optionally, the molecular weight of ethyl cellulose is typically expressed indirectly by viscosity. The ethyl cellulose of the present invention is of low molecular weight and may be STD4 and / or STD7. The number after STD typically indicates the viscosity of a 5% solution in a specific solvent (typically a mixture of 80% toluene and 20% ethanol); STD4 indicates that the typical viscosity of this grade of ethyl cellulose is about 4 mPa·s; STD7 indicates that the typical viscosity of this grade of ethyl cellulose is about 7 mPa·s.

[0021] According to the present invention, optionally, the silver powder has a D50 particle size of 1.0-1.5 μm and a tap density of 3-5 g / cm³. 3 .

[0022] According to the present invention, optionally, the glass powder has a D50 particle size of 0.5-2 μm and a Tg point of 400-500℃.

[0023] According to the present invention, optionally, the glass powder comprises 50-80 parts of Pb3O4, 10-30 parts of SiO2, and the balance being ZnO, by weight.

[0024] According to the present invention, optionally, the mass ratio of the fumed silica to the hydrogenated castor oil is 1-5:1.

[0025] According to the present invention, optionally, the solvent is one or more of alcohol ester dodecyl, alcohol ester hexadecyl, and butyl carbitol; and the dispersant is one or more of methacrylic acid, alkylphenol polyoxyethylene ether, and fatty acid polyoxyethylene ether.

[0026] A second aspect of the present invention provides a method for preparing the conductive silver paste provided in the first aspect of the present invention, the method comprising: Ethyl cellulose, acrylic resin and solvent are mixed and stirred for the first time to obtain a uniform and transparent organic carrier; After mixing the silver powder and glass powder, a second stirring is performed to obtain a uniformly dispersed mixture. The mixture, the organic carrier, the thixotropic agent, and the dispersant are mixed and then subjected to a first centrifugal dispersion, followed by grinding and dispersion in a three-roll mill to obtain a dispersed material. The dispersed material is then subjected to a second centrifugal dispersion.

[0027] According to the present invention, optionally, the first stirring can be carried out on a mixer with a rotation speed of 700 r / min, the first stirring temperature can be 50-80℃, and the time can be 3-6 h.

[0028] According to the present invention, optionally, a shear mixer is used for the second stirring, so that the silver powder and glass powder are mixed and dispersed evenly, wherein the stirring speed can be 100 rpm and the dispersion speed can be 800 rpm.

[0029] According to the present invention, optionally, the first centrifugal dispersion and the second centrifugal dispersion can be carried out in a high-speed centrifugal disperser, wherein the speed of the first centrifugal dispersion and the speed of the second centrifugal dispersion are each independently 4000-5000 rpm, and the number of centrifugations can be 4-5 times.

[0030] According to the present invention, optionally, when grinding and dispersing in a three-roll mill, the rotational speed ratio of the front, middle and rear rollers is 3:7:2, the rotational speed of the middle roller is 600 rpm, and the fineness of the dispersed material after grinding can be less than 10 μm.

[0031] According to the present invention, optionally, the glass powder of the present invention is a Pb-Si-Zn based glass powder, and the preparation method includes the following steps: Pb3O4, SiO2, and ZnO were mixed and centrifuged at 1000 r / min for 3 min using a high-speed centrifuge to ensure uniform mixing. The homogeneous mixture was then placed in a ceramic crucible and subsequently placed in a muffle furnace. The ceramic crucible had a capacity of 200 mL, and the muffle furnace was calcined at 800 °C with a heating rate of 8 °C / min for 75 min.

[0032] The calcined glass melt was placed in an iron drum filled with ice water for water quenching. The water quenching process caused the glass to cool rapidly, turning the liquid glass into a solid state. The glass was then placed in a ball mill for grinding to obtain glass powder with a D50 particle size of 0.8 μm.

[0033] A third aspect of the present invention provides a silicon solar cell, wherein the silicon solar cell uses the conductive silver paste provided in the first aspect of the present invention.

[0034] Through the above technical solutions, this paper utilizes low molecular weight ethyl cellulose and acrylic resin to reduce the viscosity of the organic carrier and enhance the fluidity of the paste. During continuous and long-term printing, the paste can maintain stable viscosity and high screen printing capability. Simultaneously, the thixotropic hydrophobic fumed silica used forms hydrogen bonds between the silanol groups on its surface and between the silanol groups and resin molecules, constructing a three-dimensional network structure and improving anti-settling ability. Hydrogenated castor oil forms tiny whiskers in organic solvents, which intertwine to form a network structure, facilitating the recovery of the paste's morphology after shearing and exhibiting excellent plasticity. This invention effectively improves the screen printing performance of conductive silver paste through the above methods, thereby effectively increasing the aspect ratio of the electrodes.

[0035] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0036] Example 1 Preparation of organic carriers: Take 4 parts of ethyl cellulose STD4, 4 parts of ethyl cellulose STD7, 2 parts of acrylic resin, 40 parts of alcohol ester dodecyl, 20 parts of alcohol ester hexadecyl, and 30 parts of butyl carbitol. Place 100 parts of the above substances in a mixer at 700 r / min and stir at 75°C for 5 h to obtain a homogeneous and transparent organic carrier.

[0037] Preparation of glass powder: S1. Take 70 parts of Pb3O4, 20 parts of SiO2, and 10 parts of ZnO. Mix them in a high-speed centrifuge at 1000 r / min for 3 min. After mixing, put the material into a ceramic crucible and then into a muffle furnace. The calcination temperature of the muffle furnace is 800℃, the heating rate is 8℃ / min, and the calcination time is 75 min. S2. The calcined glass melt is placed in an iron bucket filled with ice water for water quenching. The water quenching process causes the glass to cool rapidly, and the glass melt is then ground in a ball mill to obtain glass powder with a D50 particle size of 0.8 μm.

[0038] Preparation of conductive silver paste: S1. The silver powder and glass powder are stirred using a shear mixer to ensure that the silver powder and glass powder are evenly mixed and dispersed to obtain a mixture; wherein the stirring speed is 100 rpm and the dispersion speed is 800 rpm. S2. The mixture of organic carrier, silver powder and glass powder, thixotropic agent and dispersant are mixed and dispersed using a high-speed centrifugal disperser. The centrifugal disperser rotates at 5000 rpm and is centrifuged 5 times. The mass ratio of silver powder, glass powder, organic carrier, thixotropic agent and dispersant is 82:3:11:3:1. The mass ratio of hydrophobic fumed silica and hydrogenated castor oil in the thixotropic agent is 2:1. S3. The material after mixing and dispersing in S2 is ground and dispersed in a three-roll mill to obtain a dispersed material with a fineness of 5μm; wherein the speed ratio of the front, middle and rear rollers is 3:7:2, and the speed of the middle roller is 600rpm. S4. The dispersed material in S3 is further centrifuged and dispersed, with the centrifuge speed at 4000 rpm and the number of centrifugations at 5 times, to obtain a silver paste formula for an excellent high aspect ratio electrode.

[0039] Comparative Example 1 Preparation of organic carriers: Take 8 parts of ethyl cellulose STD100, 2 parts of acrylic resin, 40 parts of dodecayl alcohol ester, 20 parts of hexadecyl alcohol ester, and 30 parts of butyl carbitol. Place 100 parts of the above substances in a mixer at 700 r / min and stir at 75°C for 5 h to obtain a homogeneous and transparent organic carrier.

[0040] Preparation of glass powder: S1. Take 70 parts of Pb3O4, 20 parts of SiO2, and 10 parts of ZnO. Mix them in a high-speed centrifuge at 1000 r / min for 3 min. After mixing, put the material into a ceramic crucible and then into a muffle furnace. The calcination temperature of the muffle furnace is 800℃, the heating rate is 8℃ / min, and the calcination time is 75 min. S2. The calcined glass melt is placed in an iron bucket filled with ice water for water quenching. The water quenching process causes the glass to cool rapidly, and the glass melt is then ground in a ball mill to obtain glass powder with a D50 particle size of 0.8 μm.

[0041] Preparation of conductive silver paste: S1. The silver powder and glass powder are stirred using a shear mixer to ensure that the silver powder and glass powder are evenly mixed and dispersed to obtain a mixture; wherein the stirring speed is 100 rpm and the dispersion speed is 800 rpm. S2. The mixture of organic carrier, silver powder and glass powder, thixotropic agent and dispersant are mixed and dispersed using a high-speed centrifugal disperser. The centrifugal disperser rotates at 5000 rpm and is centrifuged 5 times. The mass ratio of silver powder, glass powder, organic carrier, thixotropic agent and dispersant is 82:3:11:3:1. The mass ratio of hydrophobic fumed silica and hydrogenated castor oil in the thixotropic agent is 2:1. S3. The material after mixing and dispersing in S2 is ground and dispersed in a three-roll mill to obtain a dispersed material with a fineness of 5μm; wherein the speed ratio of the front, middle and rear rollers is 3:7:2, and the speed of the middle roller is 600rpm. S4. The dispersed material in S3 is further centrifuged and dispersed, with the centrifuge speed at 4000 rpm and the number of centrifugations at 5 times, to obtain a silver paste formula for an excellent high aspect ratio electrode.

[0042] Comparative Example 2 Preparation of organic carriers: Take 8 parts of ethyl cellulose STD100, 2 parts of acrylic resin, 40 parts of dodecayl alcohol ester, 20 parts of hexadecyl alcohol ester, and 30 parts of butyl carbitol. Place 100 parts of the above substances in a mixer at 700 r / min and stir at 75°C for 5 h to obtain a homogeneous and transparent organic carrier.

[0043] Preparation of glass powder: S1. Take 70 parts of Pb3O4, 20 parts of SiO2, and 10 parts of ZnO. Mix them in a high-speed centrifuge at 1000 r / min for 3 min. After mixing, put the material into a ceramic crucible and then into a muffle furnace. The calcination temperature of the muffle furnace is 800℃, the heating rate is 8℃ / min, and the calcination time is 75 min. S2. The calcined glass melt is placed in an iron bucket filled with ice water for water quenching. The water quenching process causes the glass to cool rapidly, and the glass melt is then ground in a ball mill to obtain glass powder with a D50 particle size of 0.8 μm.

[0044] Preparation of conductive silver paste: S1. The silver powder and glass powder are stirred using a shear mixer to ensure that the silver powder and glass powder are evenly mixed and dispersed to obtain a mixture; wherein the stirring speed is 100 rpm and the dispersion speed is 800 rpm. S2. The mixture of organic carrier, silver powder and glass powder, thixotropic agent and dispersant are mixed and dispersed using a high-speed centrifugal disperser. The centrifugal disperser rotates at 5000 rpm and is centrifuged 5 times. The mass ratio of silver powder, glass powder, organic carrier, thixotropic agent and dispersant is 82:3:11:3:1. The thixotropic agent is hydrophobic fumed silica. S3. The material after mixing and dispersing in S2 is ground and dispersed in a three-roll mill to obtain a dispersed material with a fineness of 5μm; wherein the speed ratio of the front, middle and rear rollers is 3:7:2, and the speed of the middle roller is 600rpm. S4. The dispersed material in S3 is further centrifuged and dispersed, with the centrifuge speed at 4000 rpm and the number of centrifugations at 5 times, to obtain a silver paste formula for an excellent high aspect ratio electrode.

[0045] Comparative Example 3 Preparation of organic carriers: Take 8 parts of ethyl cellulose STD100, 2 parts of acrylic resin, 40 parts of dodecayl alcohol ester, 20 parts of hexadecyl alcohol ester, and 30 parts of butyl carbitol. Place 100 parts of the above substances in a mixer at 700 r / min and stir at 75°C for 5 h to obtain a homogeneous and transparent organic carrier.

[0046] Preparation of glass powder: S1. Take 70 parts of Pb3O4, 20 parts of SiO2, and 10 parts of ZnO. Mix them in a high-speed centrifuge at 1000 r / min for 3 min. After mixing, put the material into a ceramic crucible and then into a muffle furnace. The calcination temperature of the muffle furnace is 800℃, the heating rate is 8℃ / min, and the calcination time is 75 min. S2. The calcined glass melt is placed in an iron bucket filled with ice water for water quenching. The water quenching process causes the glass to cool rapidly, and the glass melt is then ground in a ball mill to obtain glass powder with a D50 particle size of 0.8 μm.

[0047] Preparation of conductive silver paste: S1. The silver powder and glass powder are stirred using a shear mixer to ensure that the silver powder and glass powder are evenly mixed and dispersed to obtain a mixture; wherein the stirring speed is 100 rpm and the dispersion speed is 800 rpm. S2. The mixture of organic carrier, silver powder and glass powder, thixotropic agent and dispersant are mixed and dispersed using a high-speed centrifugal disperser. The centrifugal disperser rotates at 5000 rpm and is centrifuged 5 times. The mass ratio of silver powder, glass powder, organic carrier, thixotropic agent and dispersant is 82:3:11:3:1. The thixotropic agent is hydrogenated castor oil. S3. The material after mixing and dispersing in S2 is ground and dispersed in a three-roll mill to obtain a dispersed material with a fineness of 5μm; wherein the speed ratio of the front, middle and rear rollers is 3:7:2, and the speed of the middle roller is 600rpm. S4. The dispersed material in S3 is further centrifuged and dispersed, with the centrifuge speed at 4000 rpm and the number of centrifugations at 5 times, to obtain a silver paste formula for an excellent high aspect ratio electrode.

[0048] Comparative Example 4 Preparation of organic carriers: Take 4 parts of ethyl cellulose STD4, 4 parts of ethyl cellulose STD7, 2 parts of acrylic resin, 40 parts of alcohol ester dodecyl, 20 parts of alcohol ester hexadecyl, and 30 parts of butyl carbitol. Place 100 parts of the above substances in a mixer at 700 r / min and stir at 75°C for 5 h to obtain a homogeneous and transparent organic carrier.

[0049] Preparation of glass powder: S1. Take 70 parts of Pb3O4, 20 parts of SiO2, and 10 parts of ZnO. Mix them in a high-speed centrifuge at 1000 r / min for 3 min. After mixing, put the material into a ceramic crucible and then into a muffle furnace. The calcination temperature of the muffle furnace is 800℃, the heating rate is 8℃ / min, and the calcination time is 75 min. S2. The calcined glass melt is placed in an iron bucket filled with ice water for water quenching. The water quenching process causes the glass to cool rapidly, and the glass melt is then ground in a ball mill to obtain glass powder with a D50 particle size of 0.8 μm.

[0050] Preparation of conductive silver paste: S1. The silver powder and glass powder are stirred using a shear mixer to ensure that the silver powder and glass powder are evenly mixed and dispersed to obtain a mixture; wherein the stirring speed is 100 rpm and the dispersion speed is 800 rpm. S2. The mixture of organic carrier, silver powder and glass powder, thixotropic agent and dispersant are mixed and dispersed using a high-speed centrifugal disperser. The centrifugal disperser rotates at 5000 rpm and is centrifuged 5 times. The mass ratio of silver powder, glass powder, organic carrier, thixotropic agent and dispersant is 79:8:6:6:1. The mass ratio of hydrophobic fumed silica and hydrogenated castor oil in the thixotropic agent is 2:1. S3. The material after mixing and dispersing in S2 is ground and dispersed in a three-roll mill to obtain a dispersed material with a fineness of 5μm; wherein the speed ratio of the front, middle and rear rollers is 3:7:2, and the speed of the middle roller is 600rpm. S4. The dispersed material in S3 is further centrifuged and dispersed, with the centrifuge speed at 4000 rpm and the number of centrifugations at 5 times, to obtain a silver paste formula for an excellent high aspect ratio electrode.

[0051] Test case Viscosity test: The apparent viscosity of the conductive silver pastes in the examples and comparative examples was measured using a cone-plate viscometer at a rotation speed of 10 rpm and a test temperature of 25°C. The test results are shown in Table 1.

[0052] Aspect Ratio Test: The conductive silver pastes of the examples and comparative examples were screen-printed and sintered to form solar cells. The height and width of the silver electrodes of the sintered cells were tested using a Schorn laser scanning gauging instrument. The measurement results are shown in Table 2.

[0053] Electrical performance testing: The conductive silver pastes of the examples and comparative examples were screen-printed and sintered to form solar cells. The electrical performance of the solar cells was tested on an I / V tester, and the test results are shown in Table 3.

[0054] Welding tensile test: The conductive silver pastes of the examples and comparative examples were screen-printed and sintered to form solar cells. The cells were then welded with flat solder strips of size 0.17*1 (with consistent welding temperature and time). The welded cells were placed on a tensile testing machine for welding tensile testing, and the peak tensile force (unit: Newton / N) displayed by the tensile testing machine was recorded. The test results are shown in Table 4.

[0055] Table 1

[0056] As shown in Table 1, the conductive silver paste of the present invention has a low viscosity, good fluidity, and can maintain a stable viscosity over a period of time.

[0057] Table 2

[0058] As shown in Table 2, the conductive silver paste of this embodiment exhibits the highest aspect ratio after printing and sintering. This is because the use of low molecular weight ethyl cellulose and acrylic resin reduces the viscosity of the organic carrier, enhances the fluidity of the paste, and improves its screen-passing ability. Furthermore, the combined use of two thixotropic agents allows the hydrophobic fumed silica to form hydrogen bonds between its surface silanol groups and between the silanol groups and resin molecules, constructing a three-dimensional network structure and improving anti-settling properties. Hydrogenated castor oil forms tiny whiskers in organic solvents, which intertwine to form a network structure, facilitating the restoration of the morphology of the sheared paste. Through the above implementation methods, an excellent aspect ratio can be achieved.

[0059] Table 3

[0060] As shown in Table 3, the short-circuit current, line resistance, and conversion efficiency of the embodiments of the present invention are improved due to the excellent aspect ratio. The excellent aspect ratio reduces the shading area of ​​the cell's light-receiving surface, resulting in more sunlight being able to reach the silicon wafer, thereby exciting more photogenerated carriers, increasing the short-circuit current, and enabling the cell to have a higher conversion efficiency.

[0061] Table 4

[0062] As shown in Table 4, the welding pull force in this embodiment of the invention is improved due to the excellent aspect ratio. The excellent aspect ratio makes the welding points stronger and better able to withstand the thermal stress during the module lamination process and the mechanical stress during operation, which greatly reduces the risk of cell interconnect strip breakage (grid breakage) and poor soldering, and improves the long-term reliability of the module.

[0063] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0064] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0065] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A conductive silver paste, characterized in that, The conductive silver paste comprises: silver powder, glass powder, organic carrier, thixotropic agent, and dispersant; the mass ratio of the silver powder, glass powder, organic carrier, thixotropic agent, and dispersant is 80-90:2-5:8-15:2-5:1; The organic carrier comprises 10-20 parts of resin and 80-90 parts of solvent by weight. The resin is ethyl cellulose and acrylic resin, wherein the molecular weight of the ethyl cellulose is 4-80 mPa·s; The thixotropic agent is fumed silica and hydrogenated castor oil.

2. The conductive silver paste according to claim 1, wherein, The silver powder has a D50 particle size of 1.0-1.5 μm and a tap density of 3-5 g / cm³. 3 ; The glass powder has a D50 particle size of 0.5-2μm and a Tg point of 400-500℃.

3. The conductive silver paste according to claim 2, wherein, The glass powder comprises 50-80 parts by weight of Pb3O4, 10-30 parts of SiO2, and the balance being ZnO.

4. The conductive silver paste according to claim 1, wherein, The mass ratio of the fumed silica to the hydrogenated castor oil is 1-5:

1.

5. The conductive silver paste according to claim 1, wherein, The solvent is one or more of alcohol ester dodecyl alcohol ester hexadecyl alcohol ester and butyl carbitol; The dispersant is one or more of methacrylic acid, alkylphenol polyoxyethylene ether, and fatty acid polyoxyethylene ether.

6. A method for preparing the conductive silver paste according to any one of claims 1-5, characterized in that, The method includes: Ethyl cellulose, acrylic resin and solvent are mixed and stirred for the first time to obtain a uniform and transparent organic carrier; After mixing the silver powder and glass powder, a second stirring is performed to obtain a uniformly dispersed mixture. The mixture, the organic carrier, the thixotropic agent, and the dispersant are mixed and then subjected to a first centrifugal dispersion, followed by grinding and dispersion in a three-roll mill to obtain a dispersed material. The dispersed material is then subjected to a second centrifugal dispersion.

7. The method according to claim 6, wherein, The first stirring temperature is 50-80℃, and the time is 3-6 hours.

8. The method according to claim 6, wherein, The first centrifugal dispersion speed and the second centrifugal dispersion speed are each independently 4000-5000 rpm.

9. The method according to claim 6, wherein, The fineness of the dispersed material is less than 10 μm.

10. A silicon solar cell, characterized in that, The silicon solar cell uses the conductive silver paste as described in any one of claims 1-5.

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