CA2534107A1 - Fine-grain silver powder and process for producing the same - Google Patents
Fine-grain silver powder and process for producing the same Download PDFInfo
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- CA2534107A1 CA2534107A1 CA002534107A CA2534107A CA2534107A1 CA 2534107 A1 CA2534107 A1 CA 2534107A1 CA 002534107 A CA002534107 A CA 002534107A CA 2534107 A CA2534107 A CA 2534107A CA 2534107 A1 CA2534107 A1 CA 2534107A1
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 194
- 238000000034 method Methods 0.000 title claims description 11
- 230000008569 process Effects 0.000 title description 2
- 229910052709 silver Inorganic materials 0.000 claims abstract description 81
- 239000004332 silver Substances 0.000 claims abstract description 81
- 239000000843 powder Substances 0.000 claims abstract description 71
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 42
- 239000007864 aqueous solution Substances 0.000 claims abstract description 41
- 238000004220 aggregation Methods 0.000 claims abstract description 27
- 230000002776 aggregation Effects 0.000 claims abstract description 27
- 238000005245 sintering Methods 0.000 claims abstract description 20
- 238000002156 mixing Methods 0.000 claims abstract description 17
- 238000010191 image analysis Methods 0.000 claims abstract description 10
- 239000002245 particle Substances 0.000 claims description 67
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 46
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 claims description 32
- 238000004519 manufacturing process Methods 0.000 claims description 32
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 23
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 13
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 13
- 239000000243 solution Substances 0.000 claims description 12
- 239000011164 primary particle Substances 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 7
- 238000005259 measurement Methods 0.000 claims description 7
- 238000001878 scanning electron micrograph Methods 0.000 claims description 6
- 238000000151 deposition Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000005304 joining Methods 0.000 claims description 3
- 239000002270 dispersing agent Substances 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims description 2
- 239000011259 mixed solution Substances 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims 1
- 230000009467 reduction Effects 0.000 abstract description 5
- 239000000654 additive Substances 0.000 abstract description 4
- 230000008021 deposition Effects 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 3
- 238000001000 micrograph Methods 0.000 abstract description 3
- 230000000996 additive effect Effects 0.000 abstract description 2
- 239000006185 dispersion Substances 0.000 abstract description 2
- 230000001747 exhibiting effect Effects 0.000 abstract 1
- 230000000977 initiatory effect Effects 0.000 abstract 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 15
- 239000004020 conductor Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 6
- 238000000691 measurement method Methods 0.000 description 6
- 239000012535 impurity Substances 0.000 description 5
- 238000006722 reduction reaction Methods 0.000 description 5
- 150000003378 silver Chemical class 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 229960005070 ascorbic acid Drugs 0.000 description 3
- 235000010323 ascorbic acid Nutrition 0.000 description 3
- 239000011668 ascorbic acid Substances 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000001828 Gelatine Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 229920000159 gelatin Polymers 0.000 description 2
- 235000019322 gelatine Nutrition 0.000 description 2
- 238000009766 low-temperature sintering Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000004931 aggregating effect Effects 0.000 description 1
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- YWQGBCXVCXMSLJ-UHFFFAOYSA-N beclobrate Chemical compound C1=CC(OC(C)(CC)C(=O)OCC)=CC=C1CC1=CC=C(Cl)C=C1 YWQGBCXVCXMSLJ-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 230000003028 elevating effect Effects 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 1
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 1
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 229910001923 silver oxide Inorganic materials 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229940116411 terpineol Drugs 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
- B22F1/054—Nanosized particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Composite Materials (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
Abstract
Fine-grain silver powder that has a grain size of minuteness not known in the prior art, exhibiting dispersion close to monodispersion with reduced grain aggregation. For obtaining the fine-grain silver powder, an aqueous solution of silver ammine complex (S1) is caused to flow through given flow channel (hereinafter referred to as ~first flow channel~). Second flow channel (b) is disposed so as to join the middle of the first flow channel (a), and an organic reducing agent optionally together with an additive (S2) is caused to flow through the second flow channel (b). At confluence (m) of the first flow channel (a) and the second flow channel (b), contact and mixing is carried out so as to effect reduction deposition. Thus, there is obtained fine-grain silver powder of such powder characteristics not known in the prior art that the average diameter of primary grain (DIA) obtained by an image analysis of scanning electron microscope images is 0.6 ~m or less (a), the crystallite diameter 10 nm or less (b) and the sintering initiation temperature 240~C or below.
Description
SPECIFICATION
FINE PARTICULATE SILVER POWDER AND PRODUCTION METHOD THEREOF
Technical Field The invention of this application relates to a fine particulate silver powder and a production method of the fine particulate silver powder.
Background Art Conventionally, for the production of a silver powder, wet reduction process has been adopted in which an aqueous solution of silver ammine complex is produced with a silver nitrate solution and ammonia water, and an organic reducing agent is added to this as described in Patent Document 1.
In late years, these silver powders are used for forming electrodes and circuits of chip parts, plasma display panel, etc. as main field of application.
[Patent document 1]: Japanese Patent Laid-Open Publication No. 2001-107101 Therefore, as for such electrodes and circuits, drastic fine production of the electrodes and circuits are demanded, and high reliability has come to be demanded along with high density and high accuracy of electric wiring.
Disclosure of the Invention Problems to be solved by the invention However, the powder particles of silver powder obtained by this conventional production method have an average particle diameter of primary particles DIA usually exceeding 0.6 ~m and an average particle diameter DSO by laser diffraction scattering particle size distribution measurement method exceeding 1.0 Vim, and the aggregation degree expressed by DSO/DIA exceeds 1.7 in actual condition.
Therefore they were unsuitable for the recent fine-pitched circuit formation, and made a significant factor of decreasing product yield.
In the meantime, the following problems have arisen from a viewpoint of usage of silver powders. It has been conventionally considered that a low crystalline silver powder is desirable for achieving a high degree of sinterbility at a low temperature because non-sintering or low-temperature-sintering type in which the heat temperature is 300°C or less has been largely used in the circuit formation using a silver paste. However, fast reduction reaction systems have had to be adopted in the production condition to obtain a low crystalline silver powder, and, as a result, only silver powders which have low crystallinity but are remarkably aggregating have been able to be obtained.
Under these circumstances, silver powders which are unprecedentedly fine particulate silver powders and have a dispersibility more approximate to monodispersibility resulting less aggregation and also have excellent low-temperature sintering properties have been desired to be provided in the market.
Accordingly, the present inventors have conducted intensive studies and made the best use of inventiveness in the production method based on a conventional production method in which an aqueous solution of silver ammine complex is obtained by mixing and reacting an aqueous silver nitrate solution and ammonia water, and an organic reducing agent is added to this to allow reduction and deposition of silver particles which are then filtered, washed and dried. As a result, it has been enabled to obtain fine particulate silver powders of a level unattainable by a conventional production method, and further, a production method for obtaining the fine particulate silver powders stably at a high yield.
Hereinbelow, the present invention will be described as divided into the "fine particulate silver powder" and the "production method".
<Fine particulate silver powder>
First, the fine particulate silver powder according to the present invention is described. The fine particulate silver powder according to the present invention is mainly characterized in that it has the following powder properties a. to c. As for these powder properties, they are enumerated as the most conspicuous properties and common in the fine particulate silver powder according to the present invention under current powder measurement techniques. Hereinbelow, each of the properties is described.
~
'. CA 02534107 2006-O1-27 The property a. is that the average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron microscope image is 0. 6 ~,m or less. Here, the "average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron microscope image " is an average particle diameter obtained by image analysis of an image of the silver powder observed by a scanning electron microscope (SEM)(wherein it is preferable to observe at a magnification of 10,000 times in the case of a fine particulate silver powder according to the present invention and at a magnification of 3000-5000 times in the case of a conventional silver powder. ) . The image analysis of the silver powder observed by a scanning electron microscope (SEM) in the present specification is performed by obtaining average particle diameter DIA by using IP-1000PC
manufactured by Asahi Engineering Co., Ltd. and conducting a round particle analysis assuming the circular threshold as 10, and the overlapping degree as 20. Because the average particle diameter DIA obtained by the image analysis of the observed image is directly obtained by the SEM observation image, the average particle diameter of the primary particles can be surely obtained. The DIA as used in the present invention is mostly falls within the range of 0.01 hum to 0.6 ~,m, as far as the present inventors observe it, but more minute particle size may be observed in reality, and therefore, no specific lower limit is described on purpose.
~
. CA 02534107 2006-O1-27 As for the property b., because the fine particulate silver powder according to the present invention shows a high dispersibility never shown by the conventional silver powders, "aggregation degree" as an index of showing this dispersibility is used. The "aggregation degree" as used in this specification is the value represented by DSO~DIA
using the above-mentioned average particle diameter DIA of primary particles and the average particle diameter DSO by laser diffraction scattering particle size distribution measurement method. Here, DSO is particle size at 50 o volume accumulation obtained by laser diffraction scattering particle size distribution measurement method, and the value of this average particle diameter DSO is not by directly and truly observing the diameter of the powder particles one by one but it can be said that an average particle diameter by assuming an aggregated powder particle as one particle (aggregated particle) is calculated. This is because powder particles of a real silver powder are usually considered not to be so-called monodisperse powder in which each individual particle is completely separated but in a condition in which several powder particles are aggregated.
However, it is usual that the value of average particle diameter DSO becomes smaller as less aggregation of powder particles is present, and they are more approximate to monodisperse. DSO of the fine particulate silver powder to be used in the present invention is a range of about 0.25 ~,m to 0.80 Vim, and a fine particulate silver powder is provided having an average particle diameter DSO of the range which has not been obtained at all by a conventional production method. The laser diffraction scattering particle size distribution measurement method as used in this specification is performed by mixing 0.1 g of fine particulate silver powder with ion-exchange water, and dispersing it with an ultrasonic homogenizer (a product of Nippon Seiki Seisaku-sho Co., Ltd., US-300T) for five minutes and measuring with a laser diffraction scattering particle size distribution measuring apparatus MicroTrac HRA 9320-X 100 type (a product of Leeds & Northrup company) .
In contrast, the "average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron micrograph" is an average particle diameter obtained by image analysis of an image of the silver powder observed by a scanning electron microscope (SEM) and the average particle diameter of the primary particles is surely observed without considering state of aggregation.
As a result, the present inventors have decided to take the value calculated by DSO~DIA calculated from the average particle diameter DSO by laser diffraction scattering particle size distribution measurement method and the average particle diameter DIA obtained by image analysis as the aggregation degree. That is to say, assuming that the DSO and DIA values can be measured with same precision in a fine particulate silver powder of the same lot, the value of DSO allowing the state of aggregation to be reflected in the measured value is supposed to be larger than that of DIA
based on the theory stated above. The value of Dso approaches the value of DIA limitlessly, and the value of Dso~DIA whlCh is the aggregation degree will approach 1 as the state of aggregation of the powder particles of the fine particulate silver powder is reduced. At the stage where the aggregation degree becomes 1, the powder can be said to be monodisperse powder in which the state of aggregation of the powder particles is not present at all.
Accordingly, the present inventors have tried to examine the correlation among the aggregation degree, viscosity of fine particulate silver powder pastes produced with a fine particulate silver powder of different aggregation degree and surface smoothness of the conductor obtained by sintering. As a result, it has been found that an extremely good correlation can be obtained. As is understood from this, it can be judged that free control of viscosity of a fine particulate silver powder paste is possible by controlling the aggregation degree of the fine particulate silver powder used therein. Besides, it has been found that if the aggregation degree is maintained to be 1.5 or less, fluctuation of the viscosity of fine particulate silver powder paste, and the surface smoothness after sintering processing can be retained in an extremely small region. In addition, as the aggregation state is eliminated, the film apparent density of the conductor obtained by sintering the fine particulate silver oxide _ g _ powder improves and, as a result, it comes to be possible to reduce the electric resistance of the formed sintered conductor.
In addition, when the aggregation degree is actually calculated, there are some cases where the value less than 1 is shown. It is considered that this is due to the assumption that DIA used for calculation of aggregation degree is a truth sphere, and although the value of aggregation degree cannot be a value under 1 theoretically, it is supposed that such a value of aggregation degree less than 1 can be obtained in reality because it is not a truth sphere.
The property c. is that crystallite diameter is 10 nm or less and there is a very close relationship between this crystallite diameter and sintering starting temperature.
That is to say, in the comparison between the silver powders having equal average particle diameter, the sintering temperature can be lower as the crystallite diameter is smaller. Therefore, the fine particulate silver powder of the present invention having a large surface energy due to its small particle size, and having a small crystallite diameter of 10 mm or less can reduce the sintering starting temperature. Here, no lower limit is defined for the crystallite diameter, and the reason therefor is that a certain measurement error occurs depending on measuring apparatus, measurement condition and so on. It is difficult to demand high reliability in the measured values in the _ g _ range where the crystallite diameter is less than 10 nm and if the lower limit is dared to be determined, it is supposed to be around 2 nm obtained as a result of study of the present inventors.
The fine particulate silver powders according to the present invention have the powder properties a. to c. as stated above, and from a viewpoint of sintering starting temperature, the fine particulate silver powder according to the present invention can be taken as a fine particulate silver powder having sintering properties lower than 240°C.
No lower limit is particularly defined for this sintering starting temperature either, but it is almost impossible to attain a sintering starting temperature less than 170°C and this is supposed to be said temperature corresponding to the lower limit in consideration of the study performed by the present inventors and general technique common sense.
Furthermore, tap bulk density of the fine particulate silver powder according to the present invention is as high as 4.0 g/cm3 as an effect resulted by the powder properties mentioned above. The tap bulk density as used herein is measured by a method comprising accurately weighing 200 g of fine particulate silver powder, placing the powder in a measuring cylinder of 150 cm3, tapping by repeating dropping at a stroke of 40 mm 1,000 times, and then measuring the volume of the fine particulate silver powder. This tap bulk density will be obtained as a higher value as the powder has theoretically more minute particle size, and it is in a state of higher dispersibility without aggregation among the particles. Considering that the tap bulk density of the conventional silver powders was less than 4.0 g/cm3, this supports that the fine particulate silver powder according to the present invention is very fine and excellent in dispersibility.
<Production method of fine particulate silver powder>
The production method according to the present is a method in which an aqueous solution of silver ammine complex is obtained by contacting and reacting an aqueous silver nitrate solution and ammonia water, and an organic reducing agent is added to this to allow reduction and deposition of silver particles which are then filtered, washed and dried, significantly characterized in that the reducing agent, silver nitrate and ammonia water are used in amounts so that they may be diluted after they are added. Conventionally, it was common to mix a reducing agent solution and a silver ammine complex aqueous solution in a tank at once and therefore, large amounts of silver nitrate, reducing agent and ammonia water should be added in order to make the silver concentration to be 10 g/1 or more, and otherwise productivity for the scale of facilities was not able to be secured.
The most important characteristic of the production method according to the present invention is that the concentration of the organic reducing agent after contacting and reacting a silver ammine complex aqueous solution and an organic reducing agent is low, and it is possible to decrease the organic reducing material which may be adsorbed and left on the surface of the powder particles of the generated silver powder, or taken in the powder particles in the growing process of the powder particles. Therefore, it is the most preferable to maintain the concentration of the organic reducing agent to 1 g/1 to 3 g/1 whereas the silver concentration is adjusted to 1 g/1 to 6 g/1 in the mixed solution.
Here, there is a proportional relationship between the silver concentration and naturally quantitatively a larger amount of silver powders can be obtained as the silver concentration is higher. However, when the silver concentration exceeds 6 g/l, there arises a tendency that the deposited silver particle becomes coarse particles, and the particle diameter will not be different at all from that of the conventional silver powders and silver powders having high dispersion properties by the present invention cannot be obtained. In contrast, if the silver concentration here is less than 1 g/1, extremely fine particulate silver powder can be obtained but because the powder is too fine, oil absorption increases and the viscosity of the paste rises, which brings about necessity to increase the amount of the organic vehicle, and leads to decrease in the film density of the finally formed sintered conductor, and tendency of increase in the electric resistance. In addition, it will not satisfy the necessary industrial productivity.
And it is the most suitable condition for obtaining fine particulate silver powder accordingto the present invention in a high yield to maintain the concentration of the organic reducing agent to 1 g/1 to 3 g/1 while the silver concentration to 1 g/1 to 6g/l. Here, the reason for adjusting the concentration of the organic reducing agent to 1 g/1 to 3 g/1 is to select it as the range most suitable for obtaining a silver powder of fine particles in a relationship with the silver concentration in the silver ammine complex aqueous solution. When the concentration of the organic reducing agent exceeds 3 g/1, the amount of the reducing agent liquid to be added to the silver ammine complex aqueous solution decreases, but the progress of aggregation of the powder particles of the reduced and deposited silver powder comes to be significant, and the amount of impurity contained in the powder particles ( In this specification, the amount of impurity is taken as carbon content.) begins to increase rapidly. On the other hand, when the concentration of the organic reducing agent is adjusted to less than 1 g/1, the total liquid volume of the reducing agent to be used increases and the amount of waste water treatment grows significantly, and it cannot satisfy the industrial economic efficiency.
The "organic reducing agent" as used herein is hydroquinone, ascorbic acid, glucose, etc. Among these, it is preferable to use hydroquinone for an organic reducing agent selectively. Hydroquinone is comparatively excellent in reactivity in the present invention in comparison with other organic reducing agents, and it may be said that it is the agent having a reaction rate most suitable for obtaining low crystalline silver powder having a small crystallite diameter.
And the other additives can be used in combination with the above-mentioned organic reducing agents. The additives as used herein are glue such as gelatine, amine-based polymeric agent, cellulose and so on and desirably they stabilize the reduction deposition process of silver powder and have functions to be a certain dispersing agent at the same time and can be used suitably selectively in accordance with the organic reducing agent, type of production process and so on.
And according to the present invention, it is desirable to adopt a method of contacting and reacting the resulting silver ammine complex aqueous solution and an organic reducing agent to reduce and deposit a fine particulate silver powder, wherein the silver ammine complex aqueous solution S1 flows in a certain flow path (referred to as "the first flow path" in the above and the following) and the second flow path b is provided which joins the first flow path a on its way as shown in Figure 1 and the organic reducing agent and an additive Sz, if required, are allowed to flow into the first flow path a though the second first flow path b and are contacted and mixed at the j oining point m of the first flow path a and the second first flow path b to reduce and deposit a silver powder (hereinafter referred to as "interflow mixing method").
By adopting such interflow mixing method, mixing of the two liquids is achieved in the shortest time and the reaction proceeds in a uniform state within the system a, and therefore, powder particles of the uniform shape can be formed. In addition, because the amount of the organic reducing agent after mixing is small when observed as the whole solution, the amount of the organic reducing agent adsorbed and left on the surface of the powder particles of the reduced and deposited silver powder decreases. As a result, the amount of impurities adsorbed on each of the fine particulate silver powder obtained by filtering and drying can be reduced. This reduction of the amount of impurities adsorbed on the fine particulate silver powder also enables to reduce the electric resistance of the sintered conductor which is formed through a silver paste.
Furthermore, it is desirable to obtain a silver ammine complex aqueous solution at a silver concentration of 2 g/1 to 12 g/1 using a silver nitrate aqueous solution of 2.6 g/1 to 48 g/1 when contacting and reacting a silver nitrate aqueous solution and ammonia water to obtain a silver ammine complex aqueous solution. The prescription of the concentration of a silver nitrate aqueous solution here is the same as prescribing the liquid volume of the silver nitrate aqueous solution and in consideration that the silver concentration of the silver ammine complex aqueous solution is adjusted to 2 g/1 to 12g/1, the concentration and the liquid volume of ammonia water to be added thereto will be necessarily decided. Although clear technical reasons have not been clear in the present stage, a fine particulate silver powder showing the best production stability and stable in quality can be obtained by using a silver nitrate aqueous solution of 2.6 g/1 to 48 g/1.
The fine particulate silver powder according to the present invention is fine as never present conventionally and has a high dispersibility and it can be understood that such a silver powder is never present in the conventional silver powders. In addition, it is enabled to efficiently obtain the fine particulate silver powder according to the present invention by adopting the production method described above.
Brief Description of the Drawings Figure 1 is a drawing expressing the concept of mixing a silver ammine complex aqueous solution and a reducing agent;
Figure 2 is a scanning electron micrograph of a fine particulate silver powder according to the present invention;
Figure 3 is a scanning electron micrograph of a fine particulate silver powder according to the present invention;
Figure 4 is a scanning electron micrograph of a fine particulate silver powder according to a conventional production method; and Figure 5 is a scanning electron micrograph of a fine particulate silver powder according to a conventional production method.
Best Mode for Carrying Out the Invention Hereinbelow, the best mode of the present invention will be described in detail by comparing with comparative examples.
Example 1 In this example, a fine particulate silver powder was produced using the production method stated above and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 9.7 liters of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wt o concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
This silver ammine complex aqueous solution was introduced into the first flow path a of 13 mm inside diameter shown in Figure 1 at a flow rate of 1, 500 ml/sec and a reducing agent was flowed from the second flow path b at a flow rate of 1, 500 ml/ sec, and they were contacted at the joining point m at a temperature of 20°C and a fine particulate silver powder was reduced and deposited. A hydroquinone aqueous solution in which 21 g of hydroquinone was dissolved in 10 liters of pure water was used as the reducing agent on this occasion. Therefore, hydroquinone concentration at the time point when mixing was finished was about 1.04 g/1, and it was a very low concentration.
Filtration was performed with a Nutsche to separate the resulting fine particulate silver powder, which was washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x 5 hours and a fine particulate silver powder was obtained. The photomicrograph of this obtained fine particulate silver powder by scanning electron microscope was shown in Figure 2.
The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in Example 2 and Comparative Examples. Therefore, measuring method and the like unidentified in the explanation described above are clarified here. The sintering starting temperature in Table 1 was measured by accurately weighing 0.5 g of a fine particulate silver powder with a balance and pressing this into a shape of a pellet at a pressure of 2 t/cm2 for one minute and performing measurement with TMA/SS6000 which was a thermomechanical analysis equipment (TMA equipment) manufactured by SEIKO Instruments Corporation and in a condition of air flow rate of 200 cc/min, temperature elevating rate of 2°C/min and retention time of 0 minute in the range of ordinary temperature to 900°C. The conductor resistance described in Table 1 was measured by using a 1mm width circuit obtained by producing a silver paste with each of the silver powders and drawing circuit on a ceramic substrate and sintering it to such a degree as allowing the measurement of resistance in the temperature range of 180 to 250°C. The composition of this silver paste was 85 wt%
of a fine particulate silver powder, 0.75 wto of ethyl cellulose, 14.25 wto of terpineol. FIB analysis measured the dimension of deposited crystal particles and was used for measurement of crystallite diameter. The carbon content was to estimate the amount of impurities adhered to the powder particles of the silver powder and measured by mixing 0.5 g of a fine particulate silver powder, 1.5 g of tungsten powder and 0.3 g of tin powder and placing the mixture in a porcelain crucible and performing the measurement by burn up infrared absorption method using EMIR-320V manufactured by Horiba, Ltd.
Example 2 In this example, a fine particulate silver powder was produced using the production conditions different from those of Example 1 and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 3.1 liters of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wto concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
This silver ammine complex aqueous solution was introduced into the first flow path a of 13 mm inside diameter shown in Figure 1 at a flow rate of 1, 500 ml/sec and a reducing agent was flowed from the second flow path b at a flow rate of 1, 500 ml/sec, and they were contacted at the joining point m at a temperature of 20°C and a fine particulate silver powder was reduced and deposited. A hydroquinone aqueous solution in which 21 g of hydroquinone was dissolved in 3.4 liters of pure water was used as the reducing agent on this occasion. Therefore, hydroquinone concentration at the time point when mixing was finished was about 3.0 g/1, and it was a very low concentration.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The photomicrograph of this obtainedfine particulate silver powder by scanning electron microscope was shown in Figure 3. The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in Example 1 and Comparative Examples.
Comparative Example 1 In this example, a fine particulate silver powder was produced using the production method shown below and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 1.0 liter of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wto concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
And this silver ammine complex solution was placed into a reaction tank and a hydroquinone aqueous solution in which 21 g of hydroquinone was dissolved in 1. 3 liters of pure water was added thereto at once as the reducing agent and agitated while the liquid temperature was maintained at 20°C for allowing reaction and a fine particulate silver powder was reduced and deposited. The hydroquinone concentration at the time point when mixing was finished was about 8.23 g/1, and it was a high concentration.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The photomicrograph of this obtainedfine particulate silver powder by scanning electron microscope was shown in Figure 4. The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in the above-mentioned Examples and the second Comparative Example.
Comparative Example 2 In this example, a fine particulate silver powder was produced using the production method shown below and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 300 ml of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wt% concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
And this silver ammine complex solution was placed into a reaction tank and a hydroquinone aqueous solution in which 3 g of gelatine was added to 200 ml of pure water and further 21 g of hydroquinone was dissolved in 700 ml of pure water was added thereto at once as the reducing agent and agitated while the liquid temperature was maintained at 20°C for allowing reaction and a fine particulate silver powder was reduced and deposited. The hydroquinone concentration at the time point when mixing was finished was about 14.5 g/1, and it was a high concentration.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The photomicrograph of this obtainedfine particulate silver powder by scanning electron microscope was shown in Figure 5. The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in the above-mentioned Examples and the second Comparative Example.
Comparative Example 3 In this example, a fine particulate silver powder was produced using the production method shown below and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 20g of polyvinylpyrrolidone was dissolved in 260 ml of pure water and further 50 g of silver nitrate was dissolved to prepare a silver nitrate aqueous solution, and 25 g of nitric acid was added thereto at once and agitated and a nitric acid solution containing silver was obtained.
The ascorbic acid concentration at the time point when mixing was finished was about 36.0 g/1.
In the meantime, 35.8 g of ascorbic acid was added and dissolved to 500 ml of pure water as a reducing agent to prepare a reducing agent solution.
And this nitric acid solution containing silver was placed into a reaction tank and the above-mentioned reducing agent solution was added thereto at once and agitated while the liquid temperature was maintained at 25°C for allowing reaction and a fine particulate silver powder was reduced and deposited.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in the above-mentioned Examples and Comparative Examples.
<Comparison and reviewing of Examples and Comparative Examples>
The above-mentioned Examples and Comparative Examples are compared referring to Table 1. In addition, it is supposed that the particle diameter of the primary particles of a powder particle can be understood distinctly if the scanning electron microscope photographs shown in Figure 2 to Figure 5 are referred to.
[Table 1]
Sample Powder Properties Properties of Sintered Conductor SSA Tap DsoDue,Dso/D,~"CrystallCarbonConductorSintering m2/gBulk m ite ontentResistanceStarting Density Diameter% -cm Tempera-g/cm3 nm tureC
Example 2.544.2 0.310.301.03 7 0.28 4.6 160 Example 1.684.7 0.550.491.12 7 0.32 5.9 190 Comparative1.184.3 1.781.021.75 9 0.88 Not 250 Example Measurable Comparative0.554.0 3.902.201.77 8 0.89 Not 250 Example Measurable Comparative0.624.0 3.031.202.53 38 0.30 Not 350 Example Measurable As is apparent from this Table 1, it will be appreciated that the fine particulate silver powders obtained in the above Examples are extremely fine and highly dispersible as compared with the silver powders produced with a conventional production method by comparing each of the powder property values and they are fine particulate powders never existed in the conventional silver powders. In addition, as for the sintered conductor properties, the film density in which the circuit is formed by using a fine particulate silver powder according to the present invention is high, and the electric resistance is reduced. In the case of each of the Comparative Examples, it can be seen that the conductor resistance is too high to be measured.
Industrial Applicability The fine particulate silver powder according to the present invention is composed of fine powder particles as could never be supposed in the conventional silver powder, and the aggregation degree of the powder particle is low, and shows very excellent dispersibility as compared with the conventional silver powders. In addition, by adopting a production method of a fine particulate silver powder according to the present invention, the residual organic matter in the obtained fine particulate silver powder has been decreased, which effects along with the high film density due to fine particulate silver powder and, as a result, enables to reduce the electric resistance of the obtained conductor.
FINE PARTICULATE SILVER POWDER AND PRODUCTION METHOD THEREOF
Technical Field The invention of this application relates to a fine particulate silver powder and a production method of the fine particulate silver powder.
Background Art Conventionally, for the production of a silver powder, wet reduction process has been adopted in which an aqueous solution of silver ammine complex is produced with a silver nitrate solution and ammonia water, and an organic reducing agent is added to this as described in Patent Document 1.
In late years, these silver powders are used for forming electrodes and circuits of chip parts, plasma display panel, etc. as main field of application.
[Patent document 1]: Japanese Patent Laid-Open Publication No. 2001-107101 Therefore, as for such electrodes and circuits, drastic fine production of the electrodes and circuits are demanded, and high reliability has come to be demanded along with high density and high accuracy of electric wiring.
Disclosure of the Invention Problems to be solved by the invention However, the powder particles of silver powder obtained by this conventional production method have an average particle diameter of primary particles DIA usually exceeding 0.6 ~m and an average particle diameter DSO by laser diffraction scattering particle size distribution measurement method exceeding 1.0 Vim, and the aggregation degree expressed by DSO/DIA exceeds 1.7 in actual condition.
Therefore they were unsuitable for the recent fine-pitched circuit formation, and made a significant factor of decreasing product yield.
In the meantime, the following problems have arisen from a viewpoint of usage of silver powders. It has been conventionally considered that a low crystalline silver powder is desirable for achieving a high degree of sinterbility at a low temperature because non-sintering or low-temperature-sintering type in which the heat temperature is 300°C or less has been largely used in the circuit formation using a silver paste. However, fast reduction reaction systems have had to be adopted in the production condition to obtain a low crystalline silver powder, and, as a result, only silver powders which have low crystallinity but are remarkably aggregating have been able to be obtained.
Under these circumstances, silver powders which are unprecedentedly fine particulate silver powders and have a dispersibility more approximate to monodispersibility resulting less aggregation and also have excellent low-temperature sintering properties have been desired to be provided in the market.
Accordingly, the present inventors have conducted intensive studies and made the best use of inventiveness in the production method based on a conventional production method in which an aqueous solution of silver ammine complex is obtained by mixing and reacting an aqueous silver nitrate solution and ammonia water, and an organic reducing agent is added to this to allow reduction and deposition of silver particles which are then filtered, washed and dried. As a result, it has been enabled to obtain fine particulate silver powders of a level unattainable by a conventional production method, and further, a production method for obtaining the fine particulate silver powders stably at a high yield.
Hereinbelow, the present invention will be described as divided into the "fine particulate silver powder" and the "production method".
<Fine particulate silver powder>
First, the fine particulate silver powder according to the present invention is described. The fine particulate silver powder according to the present invention is mainly characterized in that it has the following powder properties a. to c. As for these powder properties, they are enumerated as the most conspicuous properties and common in the fine particulate silver powder according to the present invention under current powder measurement techniques. Hereinbelow, each of the properties is described.
~
'. CA 02534107 2006-O1-27 The property a. is that the average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron microscope image is 0. 6 ~,m or less. Here, the "average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron microscope image " is an average particle diameter obtained by image analysis of an image of the silver powder observed by a scanning electron microscope (SEM)(wherein it is preferable to observe at a magnification of 10,000 times in the case of a fine particulate silver powder according to the present invention and at a magnification of 3000-5000 times in the case of a conventional silver powder. ) . The image analysis of the silver powder observed by a scanning electron microscope (SEM) in the present specification is performed by obtaining average particle diameter DIA by using IP-1000PC
manufactured by Asahi Engineering Co., Ltd. and conducting a round particle analysis assuming the circular threshold as 10, and the overlapping degree as 20. Because the average particle diameter DIA obtained by the image analysis of the observed image is directly obtained by the SEM observation image, the average particle diameter of the primary particles can be surely obtained. The DIA as used in the present invention is mostly falls within the range of 0.01 hum to 0.6 ~,m, as far as the present inventors observe it, but more minute particle size may be observed in reality, and therefore, no specific lower limit is described on purpose.
~
. CA 02534107 2006-O1-27 As for the property b., because the fine particulate silver powder according to the present invention shows a high dispersibility never shown by the conventional silver powders, "aggregation degree" as an index of showing this dispersibility is used. The "aggregation degree" as used in this specification is the value represented by DSO~DIA
using the above-mentioned average particle diameter DIA of primary particles and the average particle diameter DSO by laser diffraction scattering particle size distribution measurement method. Here, DSO is particle size at 50 o volume accumulation obtained by laser diffraction scattering particle size distribution measurement method, and the value of this average particle diameter DSO is not by directly and truly observing the diameter of the powder particles one by one but it can be said that an average particle diameter by assuming an aggregated powder particle as one particle (aggregated particle) is calculated. This is because powder particles of a real silver powder are usually considered not to be so-called monodisperse powder in which each individual particle is completely separated but in a condition in which several powder particles are aggregated.
However, it is usual that the value of average particle diameter DSO becomes smaller as less aggregation of powder particles is present, and they are more approximate to monodisperse. DSO of the fine particulate silver powder to be used in the present invention is a range of about 0.25 ~,m to 0.80 Vim, and a fine particulate silver powder is provided having an average particle diameter DSO of the range which has not been obtained at all by a conventional production method. The laser diffraction scattering particle size distribution measurement method as used in this specification is performed by mixing 0.1 g of fine particulate silver powder with ion-exchange water, and dispersing it with an ultrasonic homogenizer (a product of Nippon Seiki Seisaku-sho Co., Ltd., US-300T) for five minutes and measuring with a laser diffraction scattering particle size distribution measuring apparatus MicroTrac HRA 9320-X 100 type (a product of Leeds & Northrup company) .
In contrast, the "average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron micrograph" is an average particle diameter obtained by image analysis of an image of the silver powder observed by a scanning electron microscope (SEM) and the average particle diameter of the primary particles is surely observed without considering state of aggregation.
As a result, the present inventors have decided to take the value calculated by DSO~DIA calculated from the average particle diameter DSO by laser diffraction scattering particle size distribution measurement method and the average particle diameter DIA obtained by image analysis as the aggregation degree. That is to say, assuming that the DSO and DIA values can be measured with same precision in a fine particulate silver powder of the same lot, the value of DSO allowing the state of aggregation to be reflected in the measured value is supposed to be larger than that of DIA
based on the theory stated above. The value of Dso approaches the value of DIA limitlessly, and the value of Dso~DIA whlCh is the aggregation degree will approach 1 as the state of aggregation of the powder particles of the fine particulate silver powder is reduced. At the stage where the aggregation degree becomes 1, the powder can be said to be monodisperse powder in which the state of aggregation of the powder particles is not present at all.
Accordingly, the present inventors have tried to examine the correlation among the aggregation degree, viscosity of fine particulate silver powder pastes produced with a fine particulate silver powder of different aggregation degree and surface smoothness of the conductor obtained by sintering. As a result, it has been found that an extremely good correlation can be obtained. As is understood from this, it can be judged that free control of viscosity of a fine particulate silver powder paste is possible by controlling the aggregation degree of the fine particulate silver powder used therein. Besides, it has been found that if the aggregation degree is maintained to be 1.5 or less, fluctuation of the viscosity of fine particulate silver powder paste, and the surface smoothness after sintering processing can be retained in an extremely small region. In addition, as the aggregation state is eliminated, the film apparent density of the conductor obtained by sintering the fine particulate silver oxide _ g _ powder improves and, as a result, it comes to be possible to reduce the electric resistance of the formed sintered conductor.
In addition, when the aggregation degree is actually calculated, there are some cases where the value less than 1 is shown. It is considered that this is due to the assumption that DIA used for calculation of aggregation degree is a truth sphere, and although the value of aggregation degree cannot be a value under 1 theoretically, it is supposed that such a value of aggregation degree less than 1 can be obtained in reality because it is not a truth sphere.
The property c. is that crystallite diameter is 10 nm or less and there is a very close relationship between this crystallite diameter and sintering starting temperature.
That is to say, in the comparison between the silver powders having equal average particle diameter, the sintering temperature can be lower as the crystallite diameter is smaller. Therefore, the fine particulate silver powder of the present invention having a large surface energy due to its small particle size, and having a small crystallite diameter of 10 mm or less can reduce the sintering starting temperature. Here, no lower limit is defined for the crystallite diameter, and the reason therefor is that a certain measurement error occurs depending on measuring apparatus, measurement condition and so on. It is difficult to demand high reliability in the measured values in the _ g _ range where the crystallite diameter is less than 10 nm and if the lower limit is dared to be determined, it is supposed to be around 2 nm obtained as a result of study of the present inventors.
The fine particulate silver powders according to the present invention have the powder properties a. to c. as stated above, and from a viewpoint of sintering starting temperature, the fine particulate silver powder according to the present invention can be taken as a fine particulate silver powder having sintering properties lower than 240°C.
No lower limit is particularly defined for this sintering starting temperature either, but it is almost impossible to attain a sintering starting temperature less than 170°C and this is supposed to be said temperature corresponding to the lower limit in consideration of the study performed by the present inventors and general technique common sense.
Furthermore, tap bulk density of the fine particulate silver powder according to the present invention is as high as 4.0 g/cm3 as an effect resulted by the powder properties mentioned above. The tap bulk density as used herein is measured by a method comprising accurately weighing 200 g of fine particulate silver powder, placing the powder in a measuring cylinder of 150 cm3, tapping by repeating dropping at a stroke of 40 mm 1,000 times, and then measuring the volume of the fine particulate silver powder. This tap bulk density will be obtained as a higher value as the powder has theoretically more minute particle size, and it is in a state of higher dispersibility without aggregation among the particles. Considering that the tap bulk density of the conventional silver powders was less than 4.0 g/cm3, this supports that the fine particulate silver powder according to the present invention is very fine and excellent in dispersibility.
<Production method of fine particulate silver powder>
The production method according to the present is a method in which an aqueous solution of silver ammine complex is obtained by contacting and reacting an aqueous silver nitrate solution and ammonia water, and an organic reducing agent is added to this to allow reduction and deposition of silver particles which are then filtered, washed and dried, significantly characterized in that the reducing agent, silver nitrate and ammonia water are used in amounts so that they may be diluted after they are added. Conventionally, it was common to mix a reducing agent solution and a silver ammine complex aqueous solution in a tank at once and therefore, large amounts of silver nitrate, reducing agent and ammonia water should be added in order to make the silver concentration to be 10 g/1 or more, and otherwise productivity for the scale of facilities was not able to be secured.
The most important characteristic of the production method according to the present invention is that the concentration of the organic reducing agent after contacting and reacting a silver ammine complex aqueous solution and an organic reducing agent is low, and it is possible to decrease the organic reducing material which may be adsorbed and left on the surface of the powder particles of the generated silver powder, or taken in the powder particles in the growing process of the powder particles. Therefore, it is the most preferable to maintain the concentration of the organic reducing agent to 1 g/1 to 3 g/1 whereas the silver concentration is adjusted to 1 g/1 to 6 g/1 in the mixed solution.
Here, there is a proportional relationship between the silver concentration and naturally quantitatively a larger amount of silver powders can be obtained as the silver concentration is higher. However, when the silver concentration exceeds 6 g/l, there arises a tendency that the deposited silver particle becomes coarse particles, and the particle diameter will not be different at all from that of the conventional silver powders and silver powders having high dispersion properties by the present invention cannot be obtained. In contrast, if the silver concentration here is less than 1 g/1, extremely fine particulate silver powder can be obtained but because the powder is too fine, oil absorption increases and the viscosity of the paste rises, which brings about necessity to increase the amount of the organic vehicle, and leads to decrease in the film density of the finally formed sintered conductor, and tendency of increase in the electric resistance. In addition, it will not satisfy the necessary industrial productivity.
And it is the most suitable condition for obtaining fine particulate silver powder accordingto the present invention in a high yield to maintain the concentration of the organic reducing agent to 1 g/1 to 3 g/1 while the silver concentration to 1 g/1 to 6g/l. Here, the reason for adjusting the concentration of the organic reducing agent to 1 g/1 to 3 g/1 is to select it as the range most suitable for obtaining a silver powder of fine particles in a relationship with the silver concentration in the silver ammine complex aqueous solution. When the concentration of the organic reducing agent exceeds 3 g/1, the amount of the reducing agent liquid to be added to the silver ammine complex aqueous solution decreases, but the progress of aggregation of the powder particles of the reduced and deposited silver powder comes to be significant, and the amount of impurity contained in the powder particles ( In this specification, the amount of impurity is taken as carbon content.) begins to increase rapidly. On the other hand, when the concentration of the organic reducing agent is adjusted to less than 1 g/1, the total liquid volume of the reducing agent to be used increases and the amount of waste water treatment grows significantly, and it cannot satisfy the industrial economic efficiency.
The "organic reducing agent" as used herein is hydroquinone, ascorbic acid, glucose, etc. Among these, it is preferable to use hydroquinone for an organic reducing agent selectively. Hydroquinone is comparatively excellent in reactivity in the present invention in comparison with other organic reducing agents, and it may be said that it is the agent having a reaction rate most suitable for obtaining low crystalline silver powder having a small crystallite diameter.
And the other additives can be used in combination with the above-mentioned organic reducing agents. The additives as used herein are glue such as gelatine, amine-based polymeric agent, cellulose and so on and desirably they stabilize the reduction deposition process of silver powder and have functions to be a certain dispersing agent at the same time and can be used suitably selectively in accordance with the organic reducing agent, type of production process and so on.
And according to the present invention, it is desirable to adopt a method of contacting and reacting the resulting silver ammine complex aqueous solution and an organic reducing agent to reduce and deposit a fine particulate silver powder, wherein the silver ammine complex aqueous solution S1 flows in a certain flow path (referred to as "the first flow path" in the above and the following) and the second flow path b is provided which joins the first flow path a on its way as shown in Figure 1 and the organic reducing agent and an additive Sz, if required, are allowed to flow into the first flow path a though the second first flow path b and are contacted and mixed at the j oining point m of the first flow path a and the second first flow path b to reduce and deposit a silver powder (hereinafter referred to as "interflow mixing method").
By adopting such interflow mixing method, mixing of the two liquids is achieved in the shortest time and the reaction proceeds in a uniform state within the system a, and therefore, powder particles of the uniform shape can be formed. In addition, because the amount of the organic reducing agent after mixing is small when observed as the whole solution, the amount of the organic reducing agent adsorbed and left on the surface of the powder particles of the reduced and deposited silver powder decreases. As a result, the amount of impurities adsorbed on each of the fine particulate silver powder obtained by filtering and drying can be reduced. This reduction of the amount of impurities adsorbed on the fine particulate silver powder also enables to reduce the electric resistance of the sintered conductor which is formed through a silver paste.
Furthermore, it is desirable to obtain a silver ammine complex aqueous solution at a silver concentration of 2 g/1 to 12 g/1 using a silver nitrate aqueous solution of 2.6 g/1 to 48 g/1 when contacting and reacting a silver nitrate aqueous solution and ammonia water to obtain a silver ammine complex aqueous solution. The prescription of the concentration of a silver nitrate aqueous solution here is the same as prescribing the liquid volume of the silver nitrate aqueous solution and in consideration that the silver concentration of the silver ammine complex aqueous solution is adjusted to 2 g/1 to 12g/1, the concentration and the liquid volume of ammonia water to be added thereto will be necessarily decided. Although clear technical reasons have not been clear in the present stage, a fine particulate silver powder showing the best production stability and stable in quality can be obtained by using a silver nitrate aqueous solution of 2.6 g/1 to 48 g/1.
The fine particulate silver powder according to the present invention is fine as never present conventionally and has a high dispersibility and it can be understood that such a silver powder is never present in the conventional silver powders. In addition, it is enabled to efficiently obtain the fine particulate silver powder according to the present invention by adopting the production method described above.
Brief Description of the Drawings Figure 1 is a drawing expressing the concept of mixing a silver ammine complex aqueous solution and a reducing agent;
Figure 2 is a scanning electron micrograph of a fine particulate silver powder according to the present invention;
Figure 3 is a scanning electron micrograph of a fine particulate silver powder according to the present invention;
Figure 4 is a scanning electron micrograph of a fine particulate silver powder according to a conventional production method; and Figure 5 is a scanning electron micrograph of a fine particulate silver powder according to a conventional production method.
Best Mode for Carrying Out the Invention Hereinbelow, the best mode of the present invention will be described in detail by comparing with comparative examples.
Example 1 In this example, a fine particulate silver powder was produced using the production method stated above and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 9.7 liters of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wt o concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
This silver ammine complex aqueous solution was introduced into the first flow path a of 13 mm inside diameter shown in Figure 1 at a flow rate of 1, 500 ml/sec and a reducing agent was flowed from the second flow path b at a flow rate of 1, 500 ml/ sec, and they were contacted at the joining point m at a temperature of 20°C and a fine particulate silver powder was reduced and deposited. A hydroquinone aqueous solution in which 21 g of hydroquinone was dissolved in 10 liters of pure water was used as the reducing agent on this occasion. Therefore, hydroquinone concentration at the time point when mixing was finished was about 1.04 g/1, and it was a very low concentration.
Filtration was performed with a Nutsche to separate the resulting fine particulate silver powder, which was washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x 5 hours and a fine particulate silver powder was obtained. The photomicrograph of this obtained fine particulate silver powder by scanning electron microscope was shown in Figure 2.
The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in Example 2 and Comparative Examples. Therefore, measuring method and the like unidentified in the explanation described above are clarified here. The sintering starting temperature in Table 1 was measured by accurately weighing 0.5 g of a fine particulate silver powder with a balance and pressing this into a shape of a pellet at a pressure of 2 t/cm2 for one minute and performing measurement with TMA/SS6000 which was a thermomechanical analysis equipment (TMA equipment) manufactured by SEIKO Instruments Corporation and in a condition of air flow rate of 200 cc/min, temperature elevating rate of 2°C/min and retention time of 0 minute in the range of ordinary temperature to 900°C. The conductor resistance described in Table 1 was measured by using a 1mm width circuit obtained by producing a silver paste with each of the silver powders and drawing circuit on a ceramic substrate and sintering it to such a degree as allowing the measurement of resistance in the temperature range of 180 to 250°C. The composition of this silver paste was 85 wt%
of a fine particulate silver powder, 0.75 wto of ethyl cellulose, 14.25 wto of terpineol. FIB analysis measured the dimension of deposited crystal particles and was used for measurement of crystallite diameter. The carbon content was to estimate the amount of impurities adhered to the powder particles of the silver powder and measured by mixing 0.5 g of a fine particulate silver powder, 1.5 g of tungsten powder and 0.3 g of tin powder and placing the mixture in a porcelain crucible and performing the measurement by burn up infrared absorption method using EMIR-320V manufactured by Horiba, Ltd.
Example 2 In this example, a fine particulate silver powder was produced using the production conditions different from those of Example 1 and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 3.1 liters of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wto concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
This silver ammine complex aqueous solution was introduced into the first flow path a of 13 mm inside diameter shown in Figure 1 at a flow rate of 1, 500 ml/sec and a reducing agent was flowed from the second flow path b at a flow rate of 1, 500 ml/sec, and they were contacted at the joining point m at a temperature of 20°C and a fine particulate silver powder was reduced and deposited. A hydroquinone aqueous solution in which 21 g of hydroquinone was dissolved in 3.4 liters of pure water was used as the reducing agent on this occasion. Therefore, hydroquinone concentration at the time point when mixing was finished was about 3.0 g/1, and it was a very low concentration.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The photomicrograph of this obtainedfine particulate silver powder by scanning electron microscope was shown in Figure 3. The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in Example 1 and Comparative Examples.
Comparative Example 1 In this example, a fine particulate silver powder was produced using the production method shown below and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 1.0 liter of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wto concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
And this silver ammine complex solution was placed into a reaction tank and a hydroquinone aqueous solution in which 21 g of hydroquinone was dissolved in 1. 3 liters of pure water was added thereto at once as the reducing agent and agitated while the liquid temperature was maintained at 20°C for allowing reaction and a fine particulate silver powder was reduced and deposited. The hydroquinone concentration at the time point when mixing was finished was about 8.23 g/1, and it was a high concentration.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The photomicrograph of this obtainedfine particulate silver powder by scanning electron microscope was shown in Figure 4. The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in the above-mentioned Examples and the second Comparative Example.
Comparative Example 2 In this example, a fine particulate silver powder was produced using the production method shown below and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 63.3 g of silver nitrate was dissolved in 300 ml of pure water to prepare a silver nitrate aqueous solution, and 235 ml of 25 wt% concentration ammonia water was added thereto at once and agitated and a silver ammine complex aqueous solution was obtained.
And this silver ammine complex solution was placed into a reaction tank and a hydroquinone aqueous solution in which 3 g of gelatine was added to 200 ml of pure water and further 21 g of hydroquinone was dissolved in 700 ml of pure water was added thereto at once as the reducing agent and agitated while the liquid temperature was maintained at 20°C for allowing reaction and a fine particulate silver powder was reduced and deposited. The hydroquinone concentration at the time point when mixing was finished was about 14.5 g/1, and it was a high concentration.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The photomicrograph of this obtainedfine particulate silver powder by scanning electron microscope was shown in Figure 5. The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in the above-mentioned Examples and the second Comparative Example.
Comparative Example 3 In this example, a fine particulate silver powder was produced using the production method shown below and the properties of the obtained fine particulate silver powder were measured. And further, a silver paste was produced with the fine particulate silver powder and a test circuit was formed and the conductor resistance and sintering starting temperature were measured.
First, 20g of polyvinylpyrrolidone was dissolved in 260 ml of pure water and further 50 g of silver nitrate was dissolved to prepare a silver nitrate aqueous solution, and 25 g of nitric acid was added thereto at once and agitated and a nitric acid solution containing silver was obtained.
The ascorbic acid concentration at the time point when mixing was finished was about 36.0 g/1.
In the meantime, 35.8 g of ascorbic acid was added and dissolved to 500 ml of pure water as a reducing agent to prepare a reducing agent solution.
And this nitric acid solution containing silver was placed into a reaction tank and the above-mentioned reducing agent solution was added thereto at once and agitated while the liquid temperature was maintained at 25°C for allowing reaction and a fine particulate silver powder was reduced and deposited.
The resulting fine particulate silver powder was filtered with a Nutsche as in Example 1, washed with 100 ml of water and 50 ml of methanol and further dried at 70°C x hours and a fine particulate silver powder was obtained.
The powder properties of the fine particulate silver powder obtained as above are shown in Table 1 along with the powder properties of the silver powders obtained in the above-mentioned Examples and Comparative Examples.
<Comparison and reviewing of Examples and Comparative Examples>
The above-mentioned Examples and Comparative Examples are compared referring to Table 1. In addition, it is supposed that the particle diameter of the primary particles of a powder particle can be understood distinctly if the scanning electron microscope photographs shown in Figure 2 to Figure 5 are referred to.
[Table 1]
Sample Powder Properties Properties of Sintered Conductor SSA Tap DsoDue,Dso/D,~"CrystallCarbonConductorSintering m2/gBulk m ite ontentResistanceStarting Density Diameter% -cm Tempera-g/cm3 nm tureC
Example 2.544.2 0.310.301.03 7 0.28 4.6 160 Example 1.684.7 0.550.491.12 7 0.32 5.9 190 Comparative1.184.3 1.781.021.75 9 0.88 Not 250 Example Measurable Comparative0.554.0 3.902.201.77 8 0.89 Not 250 Example Measurable Comparative0.624.0 3.031.202.53 38 0.30 Not 350 Example Measurable As is apparent from this Table 1, it will be appreciated that the fine particulate silver powders obtained in the above Examples are extremely fine and highly dispersible as compared with the silver powders produced with a conventional production method by comparing each of the powder property values and they are fine particulate powders never existed in the conventional silver powders. In addition, as for the sintered conductor properties, the film density in which the circuit is formed by using a fine particulate silver powder according to the present invention is high, and the electric resistance is reduced. In the case of each of the Comparative Examples, it can be seen that the conductor resistance is too high to be measured.
Industrial Applicability The fine particulate silver powder according to the present invention is composed of fine powder particles as could never be supposed in the conventional silver powder, and the aggregation degree of the powder particle is low, and shows very excellent dispersibility as compared with the conventional silver powders. In addition, by adopting a production method of a fine particulate silver powder according to the present invention, the residual organic matter in the obtained fine particulate silver powder has been decreased, which effects along with the high film density due to fine particulate silver powder and, as a result, enables to reduce the electric resistance of the obtained conductor.
Claims (7)
1. A fine particulate silver powder having low aggregation properties, characterized in that the silver powder has the following powder properties in which:
a. the average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron micrograph is 0.6 µm or less;
b. the aggregation degree represented by D50/DIA using the average particle diameter DIA Of the primary particles and the average particle diameter D50 by laser diffraction scattering particle size distribution measurement is 1.5 or less; and c. the crystallite diameter is 10 nm or less.
a. the average particle diameter DIA of the primary particles obtained by image analysis of a scanning electron micrograph is 0.6 µm or less;
b. the aggregation degree represented by D50/DIA using the average particle diameter DIA Of the primary particles and the average particle diameter D50 by laser diffraction scattering particle size distribution measurement is 1.5 or less; and c. the crystallite diameter is 10 nm or less.
2. The fine particulate silver powder according to claim 1, wherein the sintering starting temperature is 240°C or less.
3. A production method of a fine particulate silver powder comprising obtaining an aqueous solution of silver ammine complex by mixing and reacting an aqueous silver nitrate solution with ammonia water, reducing and depositing silver particles by adding a reducing agent thereto and performing filtering, washing and drying the particles, characterized in that the silver particles are reduced and deposited by contacting and mixing aqueous solution of silver ammine complex with an organic reducing agent, and maintaining the silver concentration to 1 g/l to 6 g/l, and the concentration of the organic reducing agent to 1 g/l to 3 g/l in the mixed solution.
4. The production method of a fine particulate silver powder according to claim 3, characterized in that when the aqueous solution of silver ammine complex is contacted and mixed with the organic reducing agent, the silver ammine complex aqueous solution flows in a certain flow path (hereinbelow referred to as "first flow path" ) , a second flow path which joins the first flow path on its way is provided, and the organic reducing agent is allowed to flow into the first flow path through the second first flow path and is contacted and mixed with the aqueous solution of silver ammine complex at the joining point of the first flow path and the second flow path.
5. The production method of a fine particulate silver powder according to claim 3 or 4, characterized in that the method employs an aqueous solution of silver ammine complex having a silver concentration of 2 to 12 g/l obtained by mixing and reacting a silver nitrate aqueous solution having a silver nitrate concentration of 2.6 to 4.8 g/l with ammonia water.
6. The production method of a fine particulate silver powder according to any of Claims 3 to 5, wherein a dispersant is contained in the organic reducing agent to be used.
7. The production method of a fine particulate silver powder according to any of Claims 3 to 6, wherein hydroquinone is used as the organic reducing agent.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003-281659 | 2003-07-29 | ||
| JP2003281659A JP4489388B2 (en) | 2003-07-29 | 2003-07-29 | Method for producing fine silver powder |
| PCT/JP2004/010099 WO2005009651A1 (en) | 2003-07-29 | 2004-07-15 | Fine-grain silver powder and process for producing the same |
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| Publication Number | Publication Date |
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| CA2534107A1 true CA2534107A1 (en) | 2005-02-03 |
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| Application Number | Title | Priority Date | Filing Date |
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| CA002534107A Abandoned CA2534107A1 (en) | 2003-07-29 | 2004-07-15 | Fine-grain silver powder and process for producing the same |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US20080138238A1 (en) |
| JP (1) | JP4489388B2 (en) |
| KR (1) | KR101132282B1 (en) |
| CN (1) | CN100455382C (en) |
| CA (1) | CA2534107A1 (en) |
| DE (1) | DE112004001399T5 (en) |
| HK (1) | HK1092101A1 (en) |
| TW (1) | TW200504166A (en) |
| WO (1) | WO2005009651A1 (en) |
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| JP4347381B2 (en) * | 2005-05-25 | 2009-10-21 | ニホンハンダ株式会社 | Paste silver composition for adhesion of metal-based adherend, method for producing the same, and method for bonding metal-based adherend |
| KR101136766B1 (en) | 2006-07-28 | 2012-04-20 | 미쓰비시 마테리알 가부시키가이샤 | Silver fine particles and processes and equipment for the production thereof |
| TWI468240B (en) * | 2007-03-30 | 2015-01-11 | Mitsubishi Materials Corp | Silver fine particles, method for manufacturing silver fine particles, and apparatus for manufacturing silver fine particles |
| CN101911219B (en) | 2008-01-17 | 2015-12-16 | 日亚化学工业株式会社 | Conductive material and manufacture method, electronic equipment, light-emitting device and manufacture method thereof |
| JP5355007B2 (en) * | 2008-09-17 | 2013-11-27 | Ｄｏｗａエレクトロニクス株式会社 | Method for producing spherical silver powder |
| US8836130B2 (en) | 2009-01-23 | 2014-09-16 | Nichia Corporation | Light emitting semiconductor element bonded to a base by a silver coating |
| WO2010084746A1 (en) | 2009-01-23 | 2010-07-29 | 日亜化学工業株式会社 | Semiconductor device and method for manufacturing same |
| EP2390903B1 (en) | 2009-01-23 | 2016-11-02 | Nichia Corporation | Method of producing a semiconductor device by bonding silver oxide or silver on a surface of a semiconductor element with silver oxide or silver on a surface of a lead frame or of a wiring substrate, at least one of said surfaces being provided with silver oxide |
| TW201043359A (en) * | 2009-05-01 | 2010-12-16 | Du Pont | Silver particles and a process for making them |
| TW201100185A (en) * | 2009-05-01 | 2011-01-01 | Du Pont | Silver particles and a process for making them |
| JP5673536B2 (en) | 2009-07-21 | 2015-02-18 | 日亜化学工業株式会社 | Manufacturing method of conductive material, conductive material obtained by the method, electronic device including the conductive material, and light emitting device |
| US20110048527A1 (en) * | 2009-08-25 | 2011-03-03 | E.I. Du Pont De Nemours And Company | Silver thick film paste compositions and their use in conductors for photovoltaic cells |
| JP2011080094A (en) * | 2009-10-02 | 2011-04-21 | Toda Kogyo Corp | Fine silver particle, method for producing same, conductive paste containing the fine silver particles, conductive film, and electronic device |
| JP5659495B2 (en) * | 2010-01-26 | 2015-01-28 | 三菱マテリアル株式会社 | Method for forming electrode or wiring pattern |
| US8366799B2 (en) | 2010-08-30 | 2013-02-05 | E I Du Pont De Nemours And Company | Silver particles and a process for making them |
| WO2012063747A1 (en) * | 2010-11-08 | 2012-05-18 | ナミックス株式会社 | Metal particles and manufacturing method for same |
| US8574338B2 (en) | 2010-11-17 | 2013-11-05 | E I Du Pont De Nemours And Company | Reactor and continuous process for producing silver powders |
| CN102133635B (en) * | 2011-05-02 | 2012-09-19 | 杨荣春 | Silver powder and manufacturing method thereof |
| CN103702786B (en) * | 2011-07-29 | 2015-07-29 | 户田工业株式会社 | Silver microparticle and the conductive paste containing this silver-colored microparticle, conductive film and electronic device |
| JP5354041B2 (en) * | 2012-02-24 | 2013-11-27 | 住友金属鉱山株式会社 | Silver powder manufacturing method |
| CN104160490B (en) * | 2012-03-05 | 2018-07-03 | 纳美仕股份有限公司 | silver particles sintered body |
| JP5510531B1 (en) * | 2012-11-29 | 2014-06-04 | 住友金属鉱山株式会社 | Silver powder and silver paste |
| TWI508799B (en) * | 2012-12-06 | 2015-11-21 | China Steel Corp | A Method for Synthesis of Silver Powder with Adjustable Particle Size |
| JP6115405B2 (en) * | 2013-08-28 | 2017-04-19 | 住友金属鉱山株式会社 | Silver powder manufacturing method |
| JP6086145B2 (en) * | 2015-12-22 | 2017-03-01 | 住友金属鉱山株式会社 | Silver powder manufacturing method |
| KR102033545B1 (en) * | 2017-06-05 | 2019-10-17 | 대주전자재료 주식회사 | Silver particle and method of manufacture thereof |
| CN107520460A (en) * | 2017-07-26 | 2017-12-29 | 华南理工大学 | A kind of superfine nano gold/nano-cellulose composite solution and preparation method thereof |
| KR20220106128A (en) | 2019-11-28 | 2022-07-28 | 엠. 테크닉 가부시키가이샤 | Method for producing fine silver particles |
| CN114682792B (en) * | 2022-04-14 | 2024-02-13 | 宁夏中色新材料有限公司 | Spherical silver powder with high specific surface area and preparation method thereof |
| JP2023164097A (en) * | 2022-04-28 | 2023-11-10 | Ｄｏｗａエレクトロニクス株式会社 | Spherical silver powder, method for producing spherical silver powder, apparatus for producing spherical silver powder, and conductive paste |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH01287210A (en) * | 1988-05-12 | 1989-11-17 | Tanaka Kikinzoku Kogyo Kk | Manufacture of silver fine particle |
| US4979985A (en) * | 1990-02-06 | 1990-12-25 | E. I. Du Pont De Nemours And Company | Process for making finely divided particles of silver metal |
| JPH04333504A (en) * | 1991-05-10 | 1992-11-20 | Sumitomo Metal Mining Co Ltd | Continuous production of monodisperse fine silver powder |
| JP2001107101A (en) * | 1999-10-12 | 2001-04-17 | Mitsui Mining & Smelting Co Ltd | High dispersibility spherical silver powder and its producing method |
| JP4185267B2 (en) * | 2001-07-25 | 2008-11-26 | 三井金属鉱業株式会社 | Copper powder, method for producing the copper powder, copper paste using the copper powder, and printed wiring board using the copper paste |
| CN1174827C (en) * | 2001-08-17 | 2004-11-10 | 中国科学院过程工程研究所 | Preparation of hexagonal plate silver powder by chemical reduction process |
| JP2003129106A (en) * | 2001-10-25 | 2003-05-08 | Murata Mfg Co Ltd | Method for manufacturing nickel powder, nickel powder, nickel paste, and laminated ceramic electronic component |
| JP4109520B2 (en) * | 2002-09-12 | 2008-07-02 | 三井金属鉱業株式会社 | Low cohesive silver powder, method for producing the low cohesive silver powder, and conductive paste using the low cohesive silver powder |
-
2003
- 2003-07-29 JP JP2003281659A patent/JP4489388B2/en not_active Expired - Lifetime
-
2004
- 2004-06-28 TW TW093118759A patent/TW200504166A/en not_active IP Right Cessation
- 2004-07-15 KR KR1020067001513A patent/KR101132282B1/en not_active IP Right Cessation
- 2004-07-15 WO PCT/JP2004/010099 patent/WO2005009651A1/en active Application Filing
- 2004-07-15 DE DE112004001399T patent/DE112004001399T5/en not_active Withdrawn
- 2004-07-15 CN CNB2004800209878A patent/CN100455382C/en not_active Expired - Fee Related
- 2004-07-15 CA CA002534107A patent/CA2534107A1/en not_active Abandoned
- 2004-07-15 US US10/566,365 patent/US20080138238A1/en not_active Abandoned
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- 2006-11-21 HK HK06112769.8A patent/HK1092101A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR101132282B1 (en) | 2012-04-02 |
| KR20060035781A (en) | 2006-04-26 |
| DE112004001399T5 (en) | 2006-06-22 |
| JP2005048236A (en) | 2005-02-24 |
| CN1826197A (en) | 2006-08-30 |
| JP4489388B2 (en) | 2010-06-23 |
| WO2005009651A1 (en) | 2005-02-03 |
| TW200504166A (en) | 2005-02-01 |
| US20080138238A1 (en) | 2008-06-12 |
| CN100455382C (en) | 2009-01-28 |
| HK1092101A1 (en) | 2007-02-02 |
| TWI304832B (en) | 2009-01-01 |
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