KR102007856B1 - The manufacturing method of silver powder with improved dispersibility - Google Patents

Abstract

A silver salt solution preparing step (S11) of adding a silver nitrate solution, nitric acid, and ammonia water to the solvent to prepare a silver salt solution; Reducing solution manufacturing step of adding a reducing agent to the solvent and mixing to produce a reducing solution (S2); And a reduction reaction step of precipitating silver particles by mixing and stirring the silver salt solution and the reducing solution (S31). In the silver powder manufacturing method comprising a, the amount of the silver nitrate solution added in the silver salt solution preparation step (S11) To prepare a silver salt solution (S12), and by adjusting the stirring speed in the reduction reaction step (S31) to precipitate the silver particles (S32), to improve the dispersibility of the silver powder produced It is possible to provide a method of improving dispersibility while maintaining the properties of the silver powder produced without adding an additive such as a dispersant.

Description

The manufacturing method of silver powder with improved dispersibility

The present invention relates to a method for producing silver powder used in electronic components, and more particularly, to a silver paste for conductive paste having improved dispersibility used in solar cells, internal electrodes of multilayer capacitors, conductor patterns of circuit boards, and the like. It relates to a manufacturing method.

A conductive paste is a paste in which electricity flows in a dried coating film having a coating ability capable of forming a coating film, and is a fluid composition in which a conductive filler (metal filler) is dispersed in a vehicle composed of a resin binder and a solvent. It is widely used for forming external electrodes.

In particular, the silver powder used as the conductive filler is used in various fields such as electronics, chemistry, and catalysts, and by various methods such as chemical reduction, photoreduction, and ultrasonic chemical methods. Are manufactured. In the case of the chemical reduction method, silver is suitable for use in terms of powder form and mass production efficiency. Use

As a method of preparing a conventional silver powder, silver nitrate (“Dispersion mechanisms of Arabic gum in the preparation of ultrafine silver powder (Korean journal of chemical engineering., V.31 no.8, 2014, pp.1490-1495)”) AgNO ₃ ) is reacted with ascorbic acid and improved dispersibility in producing silver powder using Arabic gum as a dispersant.

In order to improve dispersibility as in the prior art, additives such as fatty acids, fatty acid salts, surfactants, organometallics, chelate formers, and protective colloids should be added, and in the case of producing silver powder without adding the dispersant, There is a problem in that short-circuit occurs when the electrode is formed of a conductive paste using the same, which has a lower dispersibility compared to the silver powder prepared by adding C.

In addition, when the dispersant is added, a process of washing impurities including the dispersant after the silver powder is additionally generated, and the physical properties such as the particle size of the silver powder prepared according to the dispersant are changed to obtain desired silver powder characteristics. There is a problem in controlling this in another step.

1.Dispersion mechanisms of Arabic gum in the preparation of ultrafine silver powder (Korean journal of chemical engineering., V.31 no. 8, 2014, pp.1490-1495).

The present invention is to solve the above problems and to provide a method for producing a silver powder with improved dispersibility without adding an additive such as a dispersant.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention provides a silver salt solution for preparing a silver salt solution by adding and mixing a silver nitrate solution, nitric acid and ammonia water to the solvent (S11); Reducing solution manufacturing step of adding a reducing agent to the solvent and mixing to produce a reducing solution (S2); And a reduction reaction step of precipitating silver particles by mixing and stirring the silver salt solution and the reducing solution (S31). In the silver powder manufacturing method comprising a, the amount of the silver nitrate solution added in the silver salt solution preparation step (S11) To prepare a silver salt solution (S12), by adjusting the stirring speed in the reduction reaction step (S31) to precipitate the silver particles (S32), to improve the dispersibility of the silver powder without using a dispersant It provides a manufacturing method.

In addition, in the silver salt solution preparation step (S11) to increase the addition amount of the silver nitrate solution to prepare a silver salt solution (S12), to reduce the stirring rate in the reduction reaction step (S31) to precipitate the silver particles (S32) It features.

In addition, the silver salt solution preparing step (S12) is a silver salt solution to prepare a silver salt solution by adding a silver nitrate solution 70 to 90 ml, nitric acid 3 to 10 ml, ammonia water 90 to 110 ml with respect to 1000 ml of the solvent, the reduction reaction Step (S32) is characterized in that the silver salt solution and the reducing solution is mixed and stirred at a stirring speed of 20 to 60rpm to precipitate the silver particles.

In addition, the reducing solution manufacturing step (S2) is a step of preparing a reducing solution of 10 to 30 g / l concentration by mixing a reducing agent of the content of 40 to 50% of the silver content contained in the silver nitrate solution with the solvent in the silver salt solution It is characterized by.

In addition, the present invention is a silver powder prepared without using a dispersant, the SEM particle diameter is measured by averaging after measuring the diameter size of each of 100 particles using a SEM (Scanning Electron Microscope), the silver is 0.5 to 2.0μm, The powder provides a silver powder having improved dispersibility in which the ratio of the D50 value measured using a Particle Size Analyzer (PSA) to the SEM particle diameter is 2.0 or less.

In addition, the silver powder is characterized in that the ratio of the D90 value measured using a particle size analyzer (PSA) to the SEM particle diameter is 3.0 or less.

In addition, the silver powder is characterized in that the ratio of the Dmax value measured using a particle size analyzer (PSA) to the SEM particle diameter is 8.0 or less.

In addition, the tap density of the silver powder is characterized in that 5.5 to 6.0 g / cm ³ .

The present invention also provides a conductive paste containing the silver powder.

In another aspect, the present invention provides a solar cell comprising an electrode formed using the conductive paste.

The present invention provides a method for producing silver powder having improved dispersibility without adding an additive such as a dispersant, and when manufacturing the silver powder according to the manufacturing method of the present invention, it is possible to reduce the cost of washing the dispersant. And, while maintaining the properties of the silver powder to be produced can provide the effect that only dispersibility is improved.

When the solar cell electrode is formed using the conductive paste formed using the silver powder having improved dispersibility, the disconnection can be significantly reduced, and the efficiency of the manufactured solar cell also provides an excellent effect.

1 shows an SEM image of silver powder prepared according to an embodiment of the present invention.
2 shows an SEM image of silver powder prepared according to a comparative example.
3 shows a disconnection evaluation image of a solar cell manufactured according to Examples and Comparative Examples of the present invention.
Figure 4 shows the disconnection evaluation image in the harsh conditions of the solar cell manufactured according to the Examples and Comparative Examples of the present invention.

Prior to describing the present invention in detail below, it is understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention, which is limited only by the scope of the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise indicated.

Throughout this specification and claims, unless otherwise indicated, the termcomprise, constitutes, and configure means to include the referenced article, step, or group of articles, and step, and any other article It is not intended to exclude a stage or group of things or groups of stages.

On the other hand, various embodiments of the present invention can be combined with any other embodiment unless clearly indicated to the contrary. Any feature indicated as particularly preferred or advantageous may be combined with any other feature and features indicated as preferred or advantageous. Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention and the effects thereof.

Silver powder production method according to an embodiment of the present invention comprises a silver salt solution preparation step (S1), a reducing solution preparation step (S2) and a reduction reaction step (S3). In the present invention, the dispersion conditions are improved by reducing the reactivity of the reaction in which silver powder is precipitated by adjusting the execution conditions of each step, even if the performance conditions of each step are adjusted to the prepared conditions before the adjustment. It is characterized by showing the same physical properties as silver powder and the like.

Hereinafter, a method of preparing the silver powder under the preconditioning (first execution condition) and the adjusted execution condition (second execution condition) will be described in detail.

1. Silver Salt Solution Preparation Step (S1)

Silver salt solution preparation step (S1) according to an embodiment of the present invention is a step of preparing a silver salt solution by mixing a silver nitrate solution, nitric acid and ammonia water in a predetermined ratio, which becomes a source of silver particles precipitated through a reduction reaction Preparing a solution that provides silver ions.

In the silver salt solution preparation step (S1), silver nitrate solution, nitric acid, and ammonia water are sequentially added to a solvent such as water, followed by stirring to prepare a silver salt solution. The concentration of the silver nitrate solution added is in the range of 300 g / L to 700 g / L. Preferably it is good in the range of 400-600 g / L, More preferably, it is 500 g / L. Hereinafter, 500 g / L of silver nitrate solution will be described as an example.

In the silver salt solution preparation step (S1), the first performance condition (S11) is as follows.

Add 55-65 ml of silver nitrate solution to 1000 ml of solvent. Preferably it is added within the range of 57 to 62 ml, more preferably 60 ml. Nitric acid is added in a ratio of 3 to 10 ml with respect to 1000 ml of solvent. Preferably it is good to add in the range of 5-8 ml, More preferably, it is good to add 5 ml. 90-110 ml of ammonia water is added with respect to 1000 ml of solvent. Preferably it is added in the range of 95 to 100 ml, more preferably 96 ml.

In the silver salt solution preparation step (S1), the second performance condition (S12) is as follows.

Add 70-90 ml of silver nitrate solution to 1000 ml of solvent. Preferably it is added in the range of 75 to 85 ml, more preferably 80 ml. Nitric acid is added in a ratio of 3 to 10 ml with respect to 1000 ml of solvent. Preferably it is good to add in the range of 5-8 ml, More preferably, it is good to add 5 ml. 90-110 ml of ammonia water is added with respect to 1000 ml of solvent. Preferably it is added in the range of 95 to 100 ml, more preferably 96 ml.

That is, in the silver salt solution preparation step (S1), the second performance condition is to increase the content of the silver nitrate solution by 1.2 to 2 times (volume ratio) under the first performance condition in preparing the silver salt solution. It is preferable to increase 1.2 to 1.7 times, and more preferably increase 1.3 to 1.5 times. When the content of the silver nitrate is increased within the above range, the silver powder having improved dispersibility can be obtained without changing physical properties such as particle size and density of the silver powder produced.

2. Reducing solution manufacturing step (S2)

Reducing solution manufacturing step according to an embodiment of the present invention (S2) is a step of preparing a reducing solution by dissolving one reducing agent in a solvent or by mixing two or more reducing agents in a predetermined ratio to prepare a reducing solution, Mixing with the prepared silver salt solution to prepare a solution to reduce the silver ions to precipitate the silver particles.

In the reducing solution preparation step (S2), one or two or more reducing agents are added to a solvent such as water at a predetermined ratio, followed by stirring to dissolve and mixed to prepare a reducing solution. The concentration of the reducing solution produced is 10 to 30 g / l. Preferably it is 10-20 g / l, More preferably, it is 20 g / l.

The reducing agent includes at least one member selected from the group consisting of ascorbic acid, alkanolamine, hydroquinone, hydrazine and formalin.

In the case of using one reducing agent, it is preferable to use hydroquinone, and the reducing agent having a content of 40 to 60% by weight of the silver content of the silver nitrate in the silver salt solution prepared in the silver salt solution preparation step may be the concentration. Mix with solvent to prepare a reducing solution. Preferably, the reducing solution may be prepared by mixing a reducing agent having a content of 45 to 55% by weight of the silver nitrate contained in the prepared silver salt solution with the solvent to the concentration.

In the case of mixing two or more kinds of reducing agents, it is preferable to use a mixture of hydroquinone and ascorbic acid.

More specifically, when hydroquinone and ascorbic acid are included in the reducing solution, 50 to 70 wt% of hydroquinone and 30 to 50 wt% of ascorbic acid are mixed and added to a concentration of 10 to 30 g / l in a solvent such as water. do. When the mixing amount of hydroquinone is higher than the above range and the mixing amount of ascorbic acid is below this range, the specific surface area of the silver powder produced decreases. That is, as the content of ascorbic acid increases, the specific surface area increases, and when the hydroquinone and ascorbic acid are mixed at the above ratios, silver particles having a high specific surface area can be precipitated.

Preferably, the hydroquinone is mixed with 55 to 65% by weight and ascorbic acid at a ratio of 35 to 45% by weight, and then added to a concentration of 10 to 20 g / l in a solvent such as water. More preferably, 60% by weight of hydroquinone and 40% by weight of ascorbic acid are mixed and added to a solvent such as water so as to have a concentration of 20 g / l.

3. Reduction reaction step (S3)

Reduction reaction step (S3) according to an embodiment of the present invention is a step of precipitating silver particles by reducing the silver ions of the silver salt solution by mixing the prepared silver salt solution and the reducing solution at a predetermined ratio.

The reduction reaction step (S3) may be reacted by slowly dropping or collectively adding the reducing solution prepared in the reducing solution preparation step (S2) while stirring the silver salt solution prepared in the silver salt solution preparation step (S1). Preferably, the batch reaction may be completed in a short time, and the batch reaction may be completed to prevent aggregation of particles and to increase dispersibility. More specifically, the reducing solution is added to the silver salt solution within 10 seconds and then stirred for 5 to 20 minutes to cause a reduction reaction in which silver particles are precipitated from the silver ions of the silver salt solution.

In the reduction reaction step (S3), the first performance condition (S31) is as follows.

When the reducing solution is added to the silver salt solution and then stirred, the reduction reaction is performed by stirring at a stirring speed of 100 to 200 rpm. It is preferable to stir at a stirring speed of 100 to 150 rpm, and more preferably to stir at a stirring speed of 100 rpm.

In the reduction reaction step (S3), the second performance condition (S32) is as follows.

When the reducing solution is added to the silver salt solution and then stirred, the reduction reaction is performed by stirring at a stirring speed of 20 to 60 rpm. It is preferable to stir at a stirring speed of 30 to 50 rpm, and more preferably to stir at a stirring speed of 40 rpm.

That is, in the reduction reaction step (S3), the second performance condition is to reduce the stirring speed of 0.2 to 0.8 times during the reduction reaction. It is preferable to reduce 0.4 to 0.8 times, and more preferably 0.5 to 0.7 times. When the stirring speed is reduced within the above range, silver powder having improved dispersibility can be obtained without changing physical properties such as particle diameter and density of the silver powder produced.

4. Purification step (S4)

Silver powder manufacturing method according to an embodiment of the present invention is a purification step of separating and washing the silver particles dispersed in an aqueous solution or slurry after filtration through the reduction reaction step (S3) by using a filtration, etc. It is possible to obtain a silver powder further comprising (S4).

More specifically, after sedimenting the silver particles in the dispersion in which the precipitated silver particles are dispersed, the supernatant of the dispersion is discarded and filtered using a centrifugal separator, and the filter medium is washed with pure water. In addition to the centrifuge mentioned in the present invention, the application of various methods for separating solid-liquid, such as filter press and decanter, is not excluded from the scope of the right. The washing process is performed by completely removing the washing water from which the powder has been washed. Therefore, the water content is reduced to less than 10%.

The silver powder prepared according to the first performance condition has a spherical shape, and the diameter of each of the 100 powders was measured using a scanning electron microscope (SEM), and the average size was 0.5 to 2.0 μm. The silver powder prepared according to the second performance condition also has a spherical shape, and the diameter of each of the 100 powders is measured using a scanning electron microscope (SEM), and the average size is 0.5 to 2.0 μm. It was. That is, the shape and particle size range of the produced silver powder were maintained.

As an indicator to indicate that the dispersibility of the silver powder prepared according to the second performance condition is improved, the number of disconnections generated when the electrode of the solar cell is formed by manufacturing the conductive paste including the prepared silver powder is indirectly determined. It can be used as an indicator, and the ratio of the PSA D50 value to the SEM particle diameter, the ratio of the PSA Dmax value to the SEM particle diameter, and the tap density can be used as direct indicators. This will be described through an experimental example to be described later.

It is possible to increase the dispersibility by adding the additive as in the conventional method, but this is a severe washing condition, the particle size, organic content, tap density, etc. when the additive is added, there is a problem that the characteristics of the powder is completely different.

The present invention is to improve the dispersibility by intentionally reducing the reactivity by the steric effect (steric effect) in the reduction reaction by controlling the external environment, such as the volume and stirring speed of the silver nitrate solution, the basis of the silver powder synthesis, , Organic content, etc. are characterized in that the properties of the powder are maintained.

In still another aspect of the present invention, it is possible to provide a conductive paste including the prepared silver powder. The composition of the conductive paste includes 80 to 90% by weight of the silver powder prepared above, 5 to 10% by weight of the organic vehicle, 1 to 5% by weight of the glass frit, and 1 to 5% by weight of the additive. More preferably, the prepared silver powder may contain 85 to 90% by weight, 5 to 8% by weight of organic vehicle, 2 to 4% by weight of glass frit, and 1 to 3% by weight of additive.

The organic vehicle is not limited, but an organic binder and a solvent may be included. Sometimes the solvent can be omitted.

The organic vehicle is required to maintain a uniformly mixed state of the metal powder and the glass frit. For example, when the conductive paste is applied to the substrate by screen printing, the conductive paste is made homogeneous and the print pattern is blurred. And properties for suppressing flow and improving the dischargeability and plate separation property of the conductive paste from the screen plate.

The organic binder included in the organic vehicle is not limited, but examples of the cellulose ester-based compound include cellulose acetate, cellulose acetate butylate, and the like, and cellulose ether compounds include ethyl cellulose, methyl cellulose, hydroxy flophyll cellulose, and hydroxy ethyl. Cellulose, hydroxy propyl methyl cellulose, hydroxy ethyl methyl cellulose, and the like. Examples of the acryl-based compound include poly acrylamide, poly methacrylate, poly methyl methacrylate, and poly ethyl methacrylate. Examples of the vinyl type include polyvinyl butyral, polyvinyl acetate, and polyvinyl alcohol. At least one organic binder may be selected and used.

Solvents used for dilution of the composition include alpha-terpineol, texanol, dioctyl phthalate, dibutyl phthalate, cyclohexane, hexane, toluene, benzyl alcohol, dioxane, diethylene glycol, ethylene glycol mono butyl ether, ethylene At least one compound selected from the group consisting of glycol mono butyl ether acetate, diethylene glycol mono butyl ether, diethylene glycol mono butyl ether acetate and the like is preferably used.

There is no restriction | limiting in particular in the composition, particle diameter, and shape of the said glass frit. Lead-free glass frits can be used as well as leaded glass frits. Preferably, as a component and content of the glass frit, PbO is 5 to 29 mol%, TeO ₂ is 20 to 34 mol%, Bi ₂ O ₃ is 3 to 20 mol%, SiO _{2 is} 20 mol% or less, 10 mol% or less of B ₂ O ₃ , alkali metals (Li, Na, K, etc.) and alkaline earth metals (Ca, Mg, etc.) may contain 10 to 20 mol%. By combining the organic content of the above components, it is possible to prevent the increase of the electrode line width, to improve the contact resistance at the sheet resistance, and to improve the short-circuit current characteristics.

The average particle diameter of the glass frit is not limited, but may have a particle diameter within the range of 0.5 to 10 μm, and may be used by mixing multi-sheet particles having different average particle diameters. Preferably, at least 1 type of glass frit uses that whose average particle diameter (D50) is 2 micrometers or more and 10 micrometers or less. Through this, the reactivity is excellent during firing, and the damage of the n-layer can be minimized, especially at high temperature, and the adhesion can be improved and the open-circuit voltage (Voc) can be excellent. In addition, it is possible to reduce the increase in the line width of the electrode during firing.

The conductive paste containing silver powder having a large spherical specific surface area prepared according to an embodiment of the present invention can increase the viscosity when preparing the paste, and when used as an electrode of the conductive material, lowers the sintering temperature of the applicable application. You can broaden your range.

Examples and Comparative Examples

(1) Preparation of silver powder according to the first performance condition

A silver salt solution was prepared by adding 60 ml of a silver nitrate solution at a concentration of 500 g / l to 1000 ml of pure water, and then sequentially adding 5 ml of nitric acid and 96 ml of ammonia water, followed by stirring. Hydroquinone was added to pure water and stirred to dissolve completely to prepare 1000 ml of a reducing solution having a concentration of 20 g / l.

The prepared reducing solution was added to the prepared silver salt solution within 10 seconds, and then stirred at 100 rpm for 5 minutes to reduce silver ions present in the silver salt solution to prepare silver particles.

After the silver particles in the mixed solution were allowed to settle, the supernatant of the mixed solution was discarded, and the mixed solution was filtered using a centrifugal separator. The media was washed with pure water and dried to obtain silver powder.

(2) Preparation of Silver Powder According to Second Performance Conditions (Examples 1 to 9)

A silver salt solution was prepared by adding a silver nitrate solution having a concentration of 500 g / l to 1000 ml of pure water in the amounts shown in Table 1, and then sequentially adding 5 ml of nitric acid and 96 ml of ammonia water, followed by stirring. Hydroquinone was added to pure water and stirred to dissolve completely to prepare 1000 ml of a reducing solution having a concentration of 20 g / l.

The prepared reducing solution was added to the prepared silver salt solution within 10 seconds, and stirred for 5 minutes at the stirring speed shown in Table 1 to reduce silver ions present in the silver salt solution to prepare silver particles.

After the silver particles in the mixed solution were allowed to settle, the supernatant of the mixed solution was discarded, and the mixed solution was filtered using a centrifugal separator. The media was washed with pure water and dried to obtain silver powder.

(3) Comparative Examples 1 to 10

A silver salt solution was prepared by adding a silver nitrate solution having a concentration of 500 g / l to 1000 ml of pure water in the amounts shown in Table 1, and then sequentially adding 5 ml of nitric acid and 96 ml of ammonia water, followed by stirring. Hydroquinone was added to pure water and stirred to dissolve completely to prepare 1000 ml of a reducing solution having a concentration of 20 g / l.

The prepared reducing solution was added to the prepared silver salt solution within 10 seconds, and stirred for 5 minutes at the stirring speed shown in Table 1 to reduce silver ions present in the silver salt solution to prepare silver particles.

After the silver particles in the mixed solution were allowed to settle, the supernatant of the mixed solution was discarded, and the mixed solution was filtered using a centrifugal separator. The media was washed with pure water and dried to obtain silver powder.

(4) Comparative Example 11

A silver salt solution was prepared by adding 60 ml of a silver nitrate solution at a concentration of 500 g / l to 1000 ml of pure water, and then sequentially adding 5 ml of nitric acid and 96 ml of ammonia water, followed by stirring. Hydroquinone was added to pure water and stirred to dissolve completely to prepare 1000 ml of a reducing solution having a concentration of 20 g / l.

1 g of arabic gum was added to the prepared silver salt solution, reducing solution, and dispersant within 10 seconds, and then stirred at 100 rpm for 5 minutes to reduce silver ions present in the silver salt solution to prepare silver particles.

After the silver particles in the mixed solution were allowed to settle, the supernatant of the mixed solution was discarded, and the mixed solution was filtered using a centrifugal separator. The media was washed with pure water and dried to obtain silver powder. In the case of using Arabic gum as a dispersant, the silver powder has a viscosity and remains sticky, so it is washed three times or more using an excess of caustic soda.

Silver Nitrate (mL) Stirring speed
(rpm) Whether to use a dispersant First performance condition 60 100 X Second performance condition Example 1 80 40 X Example 2 70 40 X Example 3 90 40 X Example 4 75 40 X Example 5 85 40 X Example 6 80 20 X Example 7 80 30 X Example 8 80 50 X Example 9 80 60 X Comparative Example 1 65 40 X Comparative Example 2 50 40 X Comparative Example 3 95 40 X Comparative Example 4 100 40 X Comparative Example 5 80 70 X Comparative Example 6 80 100 X Comparative Example 7 80 10 X Comparative Example 8 60 250 X Comparative Example 9 95 100 X Comparative Example 10 55 10 X Comparative Example 11 60 100 Arabic gum

Experimental Example

(1) scanning electron microscope (SEM) measurement

Scanning electron micrographs of the surface shape of the silver powders prepared by Example 1 and Comparative Example 11 are shown in Figs. 1 and 2, respectively. It measured and the result is shown in Table 2.

(2) PSA (particle size analyzer) measurement

0.03 g of the silver powder prepared in Examples and Comparative Examples was added to 30 ml of ethanol, and then ultrasonically dispersed for 1 minute to disperse the silver powder in ethanol, and then put into a particle size analyzer to measure the particle size distribution. In the cumulative distribution diagram of the particle size, D10 represents the particle size of 10% from the largest particle size based on the total area of the graph, and D50 represents the particle size of 50% from the largest particle size, based on the total area of the graph. Based on the total area of the graph, the particle size having a width of 90% from the largest particle size (Dmax) is expressed as D90.

(3) Tap density measurement

Table 2 shows the results of calculating the tap density versus D50 of the silver powders prepared by Examples and Comparative Examples.

(4) organic matter content measurement

Using TG / DTA EXART6600 manufactured by Seiko instrument, TGA analysis was performed at room temperature to 500 ° C. at an elevated temperature rate of 10 ° C./min to measure organic loss (Ignition loss).

SEM (μm) PSA (μm) Tap density
(g / cm ³ ) Organic matter content (%) Average D10
(/ SEM Avr.) D50
(/ SEM Avr.) D90
(/ SEM Avr.) Dmax
(/ SEM Avr.) First performance condition 1.24 1.26
(1.02) 2.51
(2.02) 4.03
(3.25) 11
(8.87) 5.49 0.72 Example 1 1.19 1.22
(1.03) 2.25
(1.89) 3.45
(2.90) 8.98
(7.55) 5.51 0.67 Example 2 1.22 1.24
(1.02) 2.32
(1.90) 3.56
(2.92) 9.61
(7.88) 5.64 0.51 Example 3 1.21 1.22
(1.01) 2.19
(1.81) 3.60
(2.98) 9.25
(7.64) 5.68 0.42 Example 4 1.27 1.21
(0.95) 2.22
(1.75) 3.67
(2.89) 9.25
(7.28) 5.68 0.46 Example 5 1.02 1.07
(1.05) 2.00
(1.96) 3.12
(3.00) 8.12
(7.96) 5.72 0.87 Example 6 1.54 1.65
(1.07) 2.86
(1.86) 3.74
(2.43) 9.91
(6.44) 5.53 0.92 Example 7 1.35 1.36
(1.01) 2.54
(1.88) 3.48
(2.58) 10.22
(7.57) 5.61 0.72 Example 8 0.97 1.02
(1.05) 1.87
(1.93) 2.88
(2.97) 7.53
(7.76) 5.87 0.73 Example 9 0.82 0.88
(1.07) 1.26
(1.54) 2.37
(2.89) 6.42
(7.83) 5.98 0.56 Comparative Example 1 1.20 1.24
(1.03) 2.83
(2.36) 4.01
(3.34) 10.72
(8.93) 5.44 0.84 Comparative Example 2 1.26 1.27
(1.01) 2.58
(2.05) 3.97
(3.15) 10.92
(8.93) 5.45 0.73 Comparative Example 3 1.38 1.37
(0.99) 3.03
(2.20) 4.56
(3.30) 11.43
(8.28) 5.37 0.59 Comparative Example 4 1.94 2.01
(1.04) 4.22
(2.18) 5.85
(3.02) 16.04
(8.27) 5.34 0.64 Comparative Example 5 1.43 1.43
(1.00) 4.01
(2.80) 5.67
(3.97) 14.66
(10.25) 5.12 0.97 Comparative Example 6 1.17 1.09
(0.93) 3.79
(3.24) 4.23
(3.62) 12.84
(10.97) 4.83 0.62 Comparative Example 7 1.71 1.77
(1.04) 3.92
(2.29) 5.31
(3.11) 14.22
(8.32) 5.46 1.07 Comparative Example 8 0.78 0.81
(1.04) 2.64
(3.38) 4.37
(5.60) 11.49
(14.73) 4.72 0.94 Comparative Example 9 1.36 1.34
(0.99) 2.99
(2.20) 5.41
(3.98) 10.94
(8.04) 5.41 0.74 Comparative Example 10 1.47 1.50
(1.02) 3.64
(2.48) 6.23
(4.24) 13.26
(9.02) 5.16 0.68 Comparative Example 11 0.93 1.03
(1.11) 2.86
(3.08) 3.72
(4.00) 10.74
(11.55) 4.99 3.21

As shown in Table 2, the SEM size of the silver powder particles prepared according to the second performance condition is 0.82 to 1.54 μm, and shows a size difference of 0.5 μm or less from the size of the silver powder particles prepared according to the first performance condition. It can be seen at about the same size.

However, the ratio of the PSA D50 value to the SEM particle size is 2.0 or less, the ratio of the PSA D90 value to the SEM particle size is 3.0 or less, and the ratio of the PSA Dmax value to the SEM particle size is 8.0 or less, which is polydispersed by light scattering. The smaller the particle size of the PSA particle size analysis, the smaller the particle and the SEM particle size, the better the dispersion.

In addition, as 5.5 to 6.0 g / cm ³ of the silver powder prepared according to the present invention, it can be seen that the dispersibility is improved by increasing than the tap density (5.49 g / cm ³ ) of the silver powder prepared according to the first performance conditions have.

(5) Preparation of Conductive Paste and Solar Cell

The electrically conductive paste was obtained by mixing 88 weight% of said silver powder, 3 weight% of glass frits, 6.5 weight% of organic vehicles, and 2.5 weight% of additives with the magnetoelectric vacuum stirring degassing apparatus, and using a three bone roll.

The obtained conductive paste was pattern printed on the front surface of the wafer by a 50 μm mesh screen printing technique, and dried at 200 to 350 ° C. for 20 to 30 seconds using a belt type drying furnace. After printing the Al paste on the back of the wafer and dried in the same way. The cell formed by the above process was calcined for 20 seconds to 30 seconds between 500 to 900 ° C. using a belt type kiln to manufacture solar cells.

(6) Conversion efficiency analysis

The manufactured cell is a solar cell efficiency measuring equipment (Halm, cetisPV-Celltest 3), conversion efficiency (Eff), short circuit current (Isc), open voltage (Voc), curve factor (FF), line resistance ( Rser) is shown in Table 3 below. In addition, the number of disconnections generated immediately after firing was measured and shown in Table 3, and images showing the degree of disconnection of the solar cell under severe conditions (temperature 85 ° C. and humidity 85%) are shown in FIGS. 3 and 4.

Isc (A) Voc (V) Eff (%) FF (%) Rser (Ω) Number of disconnection First condition 9.494 0.6372 19.66 77.75 0.00185 7 Example 1 9.694 0.6403 20.38 79.51 0.00095 0 Example 2 6.689 0.6401 20.38 79.59 0.00094 0 Example 3 9.682 0.6411 20.42 79.70 0.00096 0 Example 4 9.691 0.6417 20.43 79.58 0.00095 0 Example 5 9.689 0.6408 20.4 79.60 0.00095 0 Example 6 9.696 0.6406 20.37 79.45 0.00105 0 Example 7 9.689 0.6416 20.44 79.63 0.00101 0 Example 8 9.676 0.6403 20.34 79.52 0.00118 0 Example 9 9.698 0.6415 20.42 79.48 0.00108 0 Comparative Example 1 9.384 0.6241 19.46 78.54 0.00196 7 Comparative Example 2 9.316 0.6267 19.64 78.79 0.00205 6 Comparative Example 3 9.398 0.6284 19.48 77.89 0.00284 8 Comparative Example 4 9.365 0.6263 19.68 78.43 0.00199 8 Comparative Example 5 9.363 0.6276 19.81 78.28 0.00274 9 Comparative Example 6 9.335 0.6274 19.21 78.54 0.00275 5 Comparative Example 7 9.343 0.6284 19.71 78.35 0.00213 8 Comparative Example 8 9.398 0.6297 19.52 77.73 0.00234 7 Comparative Example 9 9.341 0.6263 19.87 78.63 0.00217 7 Comparative Example 10 9.396 0.6265 19.37 78.14 0.00189 6 Comparative Example 11 9.263 0.6154 18.15 75.43 0.00384 23

Features, structures, effects, and the like illustrated in the above-described embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, contents related to such combinations and modifications should be construed as being included in the scope of the present invention.

Claims (10)

A silver salt solution preparing step (S1) of adding a silver nitrate solution, nitric acid, and ammonia water to the solvent to prepare a silver salt solution;
Reducing solution manufacturing step of adding a reducing agent to the solvent and mixing to produce a reducing solution (S2); And
With respect to the silver powder manufacturing method comprising; a reduction reaction step (S3) of mixing the silver salt solution and the reducing solution and stirring to precipitate the silver particles,
In the silver salt solution manufacturing step (S1) to adjust the amount of the silver nitrate solution to prepare a silver salt solution, in the reduction reaction step (S3) to adjust the stirring rate to precipitate the silver particles,
The silver salt solution preparing step (S1) is a silver salt solution to prepare a silver salt solution by adding a silver nitrate solution 70 to 90 ml, nitric acid 3 to 10 ml, ammonia water 90 to 110 ml with respect to 1000 ml of the solvent,
The reduction reaction step (S3) is a silver powder manufacturing method for mixing the silver salt solution and the reducing solution and stirred at a stirring speed of 20 to 60rpm to precipitate the silver particles, thereby improving the dispersibility of the silver powder without using a dispersant.
delete delete The method of claim 1,
The reducing solution preparation step (S2) is a step of preparing a reducing solution of 10 to 30 g / l concentration by mixing a reducing agent of 45 to 55% by weight of the silver content in the silver nitrate solution with the solvent in the silver salt solution Silver powder manufacturing method which improves the dispersibility of silver powder, without using a dispersing agent.
The method of claim 1,
The SEM particle diameter measured by averaging the diameter size of each of 100 particles using a scanning electron microscope (SEM) is 0.5 to 2.0 μm,
The silver powder has a ratio of the D50 value measured using a Particle Size Analyzer (PSA) to the SEM particle diameter of 2.0 or less,
The silver powder has a ratio of the D90 value measured using a particle size analyzer (PSA) to the SEM particle diameter of 3.0 or less,
The silver powder is a method of producing a silver powder with improved dispersibility of less than 1.00 organic matter content measured by TGA analysis.
delete The method of claim 5,
The silver powder is a method of producing a silver powder with improved dispersibility, the ratio of the Dmax value measured using a particle size analyzer (PSA) to the SEM particle diameter of 8.0 or less.
The method of claim 5,
The tap density of the silver powder is 5.5 to 6.0 g / cm ³ The production method of the silver powder with improved dispersibility. delete delete

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