Copper-containing slurry suitable for high-temperature sintering and preparation method thereof

Abstract

The invention discloses copper-containing slurry suitable for high-temperature sintering and a preparation method thereof, and the copper-containing slurry comprises the following components in percentage by mass: 10-80% of copper powder, 0-80% of silver powder, 0.2-1% of low-softening-point glass powder, 0-3% of high-softening-point glass, 15-20% of an organic carrier and 0.5-3% of an organic auxiliary agent, the low-softening-point glass powder is of a Pb-Te-Li system, the softening temperature ranges from 250 DEG C to 350 DEG C, and the softening temperature is lower than the decomposition temperature of the organic coating agent on the surface of the copper powder. The preparation method comprises the following steps: adding the components according to the ratio, stirring until the components are uniformly dispersed, grinding and sieving to obtain the copper-containing slurry suitable for high-temperature sintering. According to the prepared copper-containing slurry, the low-softening-point glass powder is adopted as a key component, a liquid-phase protection layer is formed in the high-temperature sintering process, oxidation and diffusion of copper are effectively inhibited, and the oxidation resistance and the conductive stability of the copper-containing slurry are improved. Meanwhile, the slurry has good flowability and printing performance, and can meet the requirements of the photovoltaic industry for efficient and low-cost conductive materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic paste, and particularly relates to a copper-containing paste suitable for high-temperature sintering and a preparation method thereof. BACKGROUND

[0002] The photovoltaic industry has long relied on silver paste as electrode material, but the high cost and resource scarcity of silver limit its large-scale application. Copper paste becomes a potential alternative material due to its low cost and high conductivity, however, copper is easy to oxidize in the high-temperature sintering process, and copper ions are easy to diffuse to the substrate, resulting in the decrease of conductivity and the reliability of the battery. Therefore, it is an urgent need to develop a copper-containing paste which can effectively inhibit copper oxidation and diffusion in the high-temperature sintering process and a preparation process thereof. SUMMARY

[0003] An object of the present application is to solve at least the above problems and / or deficiencies, and to provide at least the advantages described hereinafter.

[0004] In order to achieve these objects and other advantages according to the present application, a copper-containing paste suitable for high-temperature sintering is provided, which comprises the following components in percentage by mass: copper powder 10-80%, silver powder 0-80%, low-softening-point glass powder 0.2-1%, high-softening-point glass 0-3%, organic carrier 15-20%, and organic auxiliary agent 0.5-3%. The low-softening-point glass powder is Pb-Te-Li system glass, and the components thereof include PbO, TeO2, SiO2, Al2O3, Li2O and B2O3, and the softening temperature is 250-350 DEG C, which is lower than the decomposition temperature of the surface organic coating agent of the copper powder.

[0005] Preferably, the particle size of the copper powder is 1-10 mu m, and the shape is spherical or quasi-spherical; and the surface organic coating agent of the copper powder is one or more of fatty acid, silane coupling agent and PVP.

[0006] Preferably, the particle size of the silver powder is 1-10 mu m, and the shape is spherical or quasi-spherical.

[0007] Preferably, the high-softening-point glass powder is Si-Cu-B system glass, and the components thereof include SiO2, CuO, B2O3, MnO2, TiO2, PbO and TeO2, and the softening temperature is 400-600 DEG C.

[0008] Preferably, the organic carrier is one or more of resin and solvent.

[0009] Preferably, the resin is one or both of ethyl cellulose and polyvinyl butyral; and the solvent is one or more of diethylene glycol butyl ether acetate, dimethyl adipate and alcohol ester twelve.

[0010] Preferably, the organic aid is one or both of polyamide wax and hydrogenated castor oil.

[0011] The application also provides a preparation method of copper-containing paste suitable for high-temperature sintering, comprising the following steps: Step one, heat the organic carrier to complete dissolution, stir uniformly, form a transparent or translucent organic solution; Step two, add copper powder, silver powder, low-softening-point glass powder, high-softening-point glass powder, organic carrier and organic aid according to the ratio, stir to uniformly disperse, grind the uniformly dispersed and lump-free paste with a three-roll mill for 3-5 times, sieve with a 400-mesh sieve, and test the fineness to be less than 10 μm to obtain the copper-containing paste suitable for high-temperature sintering.

[0012] Preferably, in step one, the heating temperature of the organic carrier is 60-90℃, the dissolution time is 1-3h, and the stirring speed is 200-500rpm.

[0013] Preferably, in step two, the stirring time is 4-8h, and the stirring speed is 100-300rpm.

[0014] The application at least has the following beneficial effects: the copper-containing paste suitable for high-temperature sintering prepared by the application uses low-softening-point glass powder as a key component, forms a liquid phase protective layer in the high-temperature sintering process, effectively inhibits the oxidation and diffusion of copper, and improves the oxidation resistance and conductive stability of the copper paste. At the same time, the paste has good fluidity and printing performance, and can meet the demand of the photovoltaic industry for efficient and low-cost conductive materials.

[0015] Other advantages, objects, and features of the application will be apparent from the following description, and will be appreciated by those skilled in the art. The true scope of the application can be defined by the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The corrosion degree of the paste prepared in Examples 1-6 and Comparative Example 1 after printing electrodes is shown in the figure. DETAILED DESCRIPTION

[0017] The application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement it according to the description.

[0018] Example 1 The copper-containing paste suitable for high-temperature sintering is composed of the following components in mass percentage: Copper powder: 80% (D50=4μm), and the organic coating agent on the surface of the copper powder is stearic acid; Low softening point glass powder: 0.5%, its composition includes: 45% PbO, 15% TeO2, 18% SiO2, 15% Al2O3, 2% Li2O and 5% B2O3, with a softening point of 300℃. High softening point glass powder: 1.6%, its composition includes: 30% SiO2, 18% CuO, 10% B2O3, 12% MnO2, 12% TiO2, 15% PbO and 3% TeO2, with a softening point of 450℃; Organic carrier: 17%, consisting of ethyl cellulose, polyvinyl butyral, dodecyl alcohol ester, and diethylene glycol butyl ether acetate; wherein, resin accounts for 12% of the organic carrier weight, including: 8% ethyl cellulose and 4% polyvinyl butyral; solvent accounts for 88% of the organic carrier weight, including: 60% dodecyl alcohol ester and 28% diethylene glycol butyl ether acetate. Organic additive 0.9%: polyamide wax; A method for preparing a copper-containing slurry suitable for high-temperature sintering includes the following steps: Step 1: Weigh the resin (ethyl cellulose, polyvinyl butyral) and solvent (dodecyl alcohol ester, diethylene glycol butyl ether acetate), mix them and dissolve them at 80°C for 2 hours with a stirring speed of 300 rpm until there are no particles. Pour them out and set aside to use to obtain the organic carrier. Step 2: Add copper powder, low softening point glass powder, high softening point glass powder, organic carrier and organic additives in proportion, stir at 200 rpm for 4 hours to obtain a uniformly dispersed slurry without lumps, grind it 4 times with a three-roll mill, and sieve it through a 400-mesh filter. After testing the fineness to be less than 10 μm, a copper-containing slurry suitable for high-temperature sintering is obtained.

[0019] Example 2 By mass percentage, copper-containing paste suitable for high-temperature sintering consists of the following components: Copper powder: 80% (D50=4μm), the organic coating agent on the surface of the copper powder is stearic acid; Low softening point glass powder: 0.2%, its composition includes: 45% PbO, 15% TeO2, 18% SiO2, 15% Al2O3, 2% Li2O and 5% B2O3, with a softening point of 300℃. High softening point glass powder: 1.9%, its composition includes: 30% SiO2, 18% CuO, 10% B2O3, 12% MnO2, 12% TiO2, 15% PbO and 3% TeO2, with a softening point of 450℃; Organic vehicle: 17%, ethyl cellulose, polyvinyl butyral, alcohol ester twelve, diethylene glycol butyl ether acetate; among them, the resin accounts for 12% of the weight of the organic vehicle, including: ethyl cellulose 8%, polyvinyl butyral 4%; the solvent accounts for 88% of the weight of the organic vehicle, including: alcohol ester twelve 60%, diethylene glycol butyl ether acetate 28%; Organic aid 0.9%: polyamide wax; The preparation method is the same as that of example 1.

[0020] Example 3 The copper-containing paste suitable for high-temperature sintering is composed of the following components by mass percentage: Copper powder: 50% (D50=4μm), the organic coating agent on the surface of the copper powder is stearic acid; Silver powder: 30% (D50=1.5μm); Low-softening-point glass powder: 0.5%, the composition includes: 45% PbO, 15% TeO2, 18% SiO2, 15% Al2O3, 2% Li2O and 5% B2O3, and the softening point is 300℃; High-softening-point glass powder: 1.6%, the composition includes: 30% SiO2, 18% CuO, 10% B2O3, 12% MnO2, 12% TiO2, 15% PbO and 3% TeO2, and the softening point is 450℃; Organic vehicle: 17%, ethyl cellulose, polyvinyl butyral, alcohol ester twelve, diethylene glycol butyl ether acetate; among them, the resin accounts for 12% of the weight of the organic vehicle, including: ethyl cellulose 8%, polyvinyl butyral 4%; the solvent accounts for 88% of the weight of the organic vehicle, including: alcohol ester twelve 60%, diethylene glycol butyl ether acetate 28%; Organic aid 0.9%: polyamide wax; A preparation method of a copper-containing paste suitable for high-temperature sintering, comprising the following steps: Step one, weigh the resin (ethyl cellulose, polyvinyl butyral) and the solvent (alcohol ester twelve, diethylene glycol butyl ether acetate), mix and dissolve at 80℃ for 2 hours, the stirring speed is 300rpm, pour out after there is no particulate matter, and get the organic vehicle; Step two, add copper powder, silver powder, low-softening-point glass powder, high-softening-point glass powder, organic vehicle and organic aid according to the ratio, stir at a speed of 200rpm for 4 hours, get a uniformly dispersed paste without clumps, use a three-roll mill to grind 4 times, sieve with a 400-mesh sieve, test the fineness less than 10μm, and get the copper-containing paste suitable for high-temperature sintering.

[0021] Example 4 The copper-containing paste for high-temperature sintering consists of the following components by mass percentage: Copper powder: 50% (D50=4μm), and the organic coating agent on the surface of the copper powder is stearic acid; Silver powder: 30% (D50=1.5μm); Low-softening-point glass powder: 0.2%, and the composition includes 45% of PbO, 15% of TeO2, 18% of SiO2, 15% of Al2O3, 2% of Li2O, and 5% of B2O3, and the softening point is 300℃; High-softening-point glass powder: 1.9%, and the composition includes 30% of SiO2, 18% of CuO, 10% of B2O3, 12% of MnO2, 12% of TiO2, 15% of PbO, and 3% of TeO2, and the softening point is 450℃; Organic carrier: 17%, which is ethyl cellulose, polyvinyl butyral, alcohol ester twelve, diethylene glycol butyl ether acetate; among them, the resin accounts for 12% of the weight of the organic carrier, including 8% of ethyl cellulose and 4% of polyvinyl butyral; the solvent accounts for 88% of the weight of the organic carrier, including 60% of alcohol ester twelve and 28% of diethylene glycol butyl ether acetate; Organic auxiliary agent 0.9%: polyamide wax; The preparation method is the same as that in Embodiment 3.

[0022] Embodiment 5 The copper-containing paste for high-temperature sintering consists of the following components by mass percentage: Copper powder: 20% (D50=4μm), and the organic coating agent on the surface of the copper powder is stearic acid; Silver powder: 60% (D50=1.5μm); Low-softening-point glass powder: 0.5%, and the composition includes 45% of PbO, 15% of TeO2, 18% of SiO2, 15% of Al2O3, 2% of Li2O, and 5% of B2O3, and the softening point is 300℃; High-softening-point glass powder: 1.6%, and the composition includes 30% of SiO2, 18% of CuO, 10% of B2O3, 12% of MnO2, 12% of TiO2, 15% of PbO, and 3% of TeO2, and the softening point is 450℃; Organic carrier: 17%, which is ethyl cellulose, polyvinyl butyral, alcohol ester twelve, diethylene glycol butyl ether acetate; among them, the resin accounts for 12% of the weight of the organic carrier, including 8% of ethyl cellulose and 4% of polyvinyl butyral; the solvent accounts for 88% of the weight of the organic carrier, including 60% of alcohol ester twelve and 28% of diethylene glycol butyl ether acetate; Organic auxiliary agent 0.9%: polyamide wax; The preparation method is the same as that in Embodiment 3.

[0023] Example 6 The copper-containing paste suitable for high-temperature sintering is composed of the following components by mass percentage: Copper powder: 20% (D50 = 4 μm), and the organic coating agent on the surface of the copper powder is stearic acid; Silver powder: 60% (D50 = 1.5 μm); Low-softening-point glass powder: 0.2%, and the composition includes 45% of PbO, 15% of TeO2, 18% of SiO2, 15% of Al2O3, 2% of Li2O, and 5% of B2O3, and the softening point is 300℃; High-softening-point glass powder: 1.9%, and the composition includes 30% of SiO2, 18% of CuO, 10% of B2O3, 12% of MnO2, 12% of TiO2, 15% of PbO, and 3% of TeO2, and the softening point is 450℃; Organic carrier: 17%, which is ethyl cellulose, polyvinyl butyral, alcohol ester twelve, diethylene glycol butyl ether acetate; among them, the resin accounts for 12% of the weight of the organic carrier, including 8% of ethyl cellulose and 4% of polyvinyl butyral; the solvent accounts for 88% of the weight of the organic carrier, including 60% of alcohol ester twelve and 28% of diethylene glycol butyl ether acetate; Organic auxiliary agent 0.9%: polyamide wax; The preparation method is the same as that in Example 3.

[0024] Comparative Example 1 The copper-containing paste suitable for high-temperature sintering is composed of the following components by mass percentage: Copper powder: 80% (D50 = 4 μm), and the organic coating agent on the surface of the copper powder is stearic acid; High-softening-point glass powder: 2.1%, and the composition includes 30% of SiO2, 18% of CuO, 10% of B2O3, 12% of MnO2, 12% of TiO2, 15% of PbO, and 3% of TeO2, and the softening point is 450℃; Organic carrier: 17%, which is ethyl cellulose, polyvinyl butyral, alcohol ester twelve, diethylene glycol butyl ether acetate; among them, the resin accounts for 12% of the weight of the organic carrier, including 8% of ethyl cellulose and 4% of polyvinyl butyral; the solvent accounts for 88% of the weight of the organic carrier, including 60% of alcohol ester twelve and 28% of diethylene glycol butyl ether acetate; Organic auxiliary agent 0.9%: polyamide wax; A preparation method of a copper-containing paste suitable for high-temperature sintering, comprising the following steps: Step one, take resin (ethyl cellulose, polyvinyl butyral) and solvent (alcohol ester twelve, diethylene glycol butyl ether acetate), mix and dissolve at 80℃ for 2 hours, stirring speed is 300rpm, pour out after no particles, get organic carrier; Step two, add copper powder, high softening point glass powder, organic carrier and organic additives according to the ratio, stirring speed is 200rpm, stirring time is 4 hours, get uniformly dispersed slurry without agglomeration, use three roll mill to grind for 4 times, sieve with 400 mesh screen, test fineness less than 10μm, get copper containing slurry suitable for high temperature sintering.

[0025] Comparative example 2 The copper containing slurry suitable for high temperature sintering is composed of the following components by mass percentage: Copper powder: 50% (D50=4μm), organic coating agent on the surface of copper powder is stearic acid; Silver powder: 30% (D50=1.5μm); High softening point glass powder: 2.1%, its composition includes: 30% of SiO2, 18% of CuO, 10% of B2O3, 12% of MnO2, 12% of TiO2, 15% of PbO and 3% of TeO2, softening point is 450℃; Organic carrier: 17%, ethyl cellulose, polyvinyl butyral, alcohol ester twelve, diethylene glycol butyl ether acetate; among them, resin accounts for 12% of the weight of organic carrier, including: ethyl cellulose 8%, polyvinyl butyral 4%; solvent accounts for 88% of the weight of organic carrier, including: alcohol ester twelve 60%, diethylene glycol butyl ether acetate 28%; Organic additive 0.9%: polyamide wax; A preparation method of copper containing slurry suitable for high temperature sintering, including the following steps: Step one, take resin (ethyl cellulose, polyvinyl butyral) and solvent (alcohol ester twelve, diethylene glycol butyl ether acetate), mix and dissolve at 80℃ for 2 hours, stirring speed is 300rpm, pour out after no particles, get organic carrier; Step two, add copper powder, silver powder, high softening point glass powder, organic carrier and organic additives according to the ratio, stirring speed is 200rpm, stirring time is 4 hours, get uniformly dispersed slurry without agglomeration, use three roll mill to grind for 4 times, sieve with 400 mesh screen, test fineness less than 10μm, get copper containing slurry suitable for high temperature sintering.

[0026] The copper-containing paste obtained from Examples 1-6 and the paste of Comparative Examples 1-2 were printed on N-type silicon wafers by screen printing technology, and then dried and sintered to complete the metallization (sintering temperature reached 730°C). The tensile strength, resistivity and corrosion degree of the electrodes were tested to determine the influence of the main grid electrode on the efficiency and reliability of the battery sheet.

[0027] The test results are shown in Table 1 and Figure 1

[0028] Table 1 Performance of different pastes As can be seen from Table 1, the resistivity of Examples 1-6 is significantly lower than that of Comparative Examples 1-2. This is because the softening temperature of the low-softening-point glass powder is lower than the decomposition temperature of the organic coating agent on the surface of the copper powder, forming a liquid phase protective layer during high-temperature sintering, inhibiting the oxidation of copper to form insulating or high-resistance oxides, and preventing the diffusion of copper ions to the substrate. Figure 1 As can be seen from Table 1 and

[0029] Although the embodiments of the present application have been disclosed as above, they are not limited to the application listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.​

Claims

1. A copper-containing slurry suitable for high-temperature sintering, characterized in that, By weight percentage, it comprises the following components: 10-80% copper powder, 0-80% silver powder, 0.2-1% low softening point glass powder, 0-3% high softening point glass, 15-20% organic carrier, and 0.5-3% organic additives; The low softening point glass powder is a Pb-Te-Li system glass, whose composition includes: PbO, TeO2, SiO2, Al2O3, Li2O and B2O3, with a softening temperature of 250-350℃, which is lower than the decomposition temperature of the organic coating agent on the surface of copper powder.

2. The copper-containing slurry suitable for high-temperature sintering according to claim 1, characterized in that, The copper powder has a particle size of 1-10 μm and a spherical or near-spherical shape; the organic coating agent on the surface of the copper powder is one or more of fatty acids, silane coupling agents, and PVP.

3. The copper-containing slurry suitable for high-temperature sintering according to claim 1, characterized in that, The silver powder has a particle size of 1–10 μm and is spherical or near-spherical in shape.

4. The copper-containing slurry suitable for high-temperature sintering according to claim 1, characterized in that, The high softening point glass powder is a Si-Cu-B system glass, whose composition includes: SiO2, CuO, B2O3, MnO2, TiO2, PbO and TeO2, and its softening temperature is 400-600℃.

5. The copper-containing slurry suitable for high-temperature sintering according to claim 1, characterized in that, The organic carrier is one or more of a resin and a solvent.

6. The copper-containing slurry suitable for high-temperature sintering according to claim 5, characterized in that, The resin is one or two of ethyl cellulose and polyvinyl butyral; the solvent is one or more of diethylene glycol butyl ether acetate, dimethyl adipate, and dodecyl alcohol ester.

7. The copper-containing slurry suitable for high-temperature sintering according to claim 1, characterized in that, The organic additive is one or both of polyamide wax and hydrogenated castor oil.

8. A method for preparing a copper-containing slurry suitable for high-temperature sintering according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Heat the organic carrier until it is completely dissolved, stir well, and form a transparent or translucent organic solution; Step 2: Add copper powder, silver powder, low softening point glass powder, high softening point glass powder, organic carrier and organic additives in proportion, stir until uniformly dispersed, grind the uniformly dispersed slurry without lumps 3 to 5 times with a three-roll mill, sieve it through a 400-mesh filter, and after testing the fineness to be less than 10μm, a copper-containing slurry suitable for high-temperature sintering is obtained.

9. The method for preparing copper-containing slurry suitable for high-temperature sintering according to claim 8, characterized in that, In step one, the heating temperature of the organic carrier is 60-90℃, the dissolution time is 1-3h, and the stirring speed is 200-500rpm.

10. The method for preparing copper-containing slurry suitable for high-temperature sintering according to claim 8, characterized in that, In step two, the stirring time is 4 to 8 hours and the stirring speed is 100 to 300 rpm.

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