CN118055817A - Method for producing phosphorus-containing silver-coated copper particles and phosphorus-containing silver-coated copper particles - Google Patents
Method for producing phosphorus-containing silver-coated copper particles and phosphorus-containing silver-coated copper particles Download PDFInfo
- Publication number
- CN118055817A CN118055817A CN202380013869.7A CN202380013869A CN118055817A CN 118055817 A CN118055817 A CN 118055817A CN 202380013869 A CN202380013869 A CN 202380013869A CN 118055817 A CN118055817 A CN 118055817A
- Authority
- CN
- China
- Prior art keywords
- silver
- phosphorus
- coated copper
- copper particles
- mass
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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
- 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
- B22F1/17—Metallic particles coated with metal
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/42—Coating with noble metals
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/42—Coating with noble metals
- C23C18/44—Coating with noble metals using reducing agents
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Powder Metallurgy (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
Abstract
含磷的银被覆铜颗粒在铜母粒的表面的至少一部分具有含有磷(P)元素的银被覆层，IO 2/(WAg×WP)×1000的值为1.9以下。IO为85℃且85％RH保存时的经过7天后的氧增加量(质量％)。WAg为含磷的银被覆铜颗粒中所含的银(Ag)元素的含有比例(质量％)。WP为含磷的银被覆铜颗粒中所含的磷(P)元素的含有比例(质量ppm)。含磷的银被覆铜颗粒通过如下方法制造：使银化合物和磷酸或其盐共存于铜母粒的分散液中，在铜母粒的表面析出形成含有磷的银被覆层。The phosphorus-containing silver-coated copper particles have a silver coating layer containing phosphorus (P) element on at least a portion of the surface of the copper mother particle, and the value of I O 2 /(W Ag ×W P )×1000 is 1.9 or less. I O is the amount of oxygen increase (mass %) after 7 days when stored at 85° C. and 85% RH. W Ag is the content ratio (mass %) of the silver (Ag) element contained in the phosphorus-containing silver-coated copper particles. W P is the content ratio (mass ppm) of the phosphorus (P) element contained in the phosphorus-containing silver-coated copper particles. The phosphorus-containing silver-coated copper particles are manufactured by the following method: a silver compound and phosphoric acid or a salt thereof are allowed to coexist in a dispersion of the copper mother particle, and a phosphorus-containing silver coating layer is precipitated on the surface of the copper mother particle.
Description
Technical Field
The present invention relates to a method for producing phosphorus-containing silver-coated copper particles and phosphorus-containing silver-coated copper particles.
Background
Silver is used as a wiring material for electronic parts. Electronic components are becoming increasingly functional year by year, and there is also increasing demand for lower price of silver wiring. Silver wiring is generally manufactured by a method of sintering silver particles contained in a paste. The reason why silver particles are used in a wiring material with a large consumption is that excellent characteristics of high oxidation resistance and high conductivity are obtained by forming wiring by sintering silver particles in air. However, since silver is an expensive material, an alternative material is required. From such a viewpoint, development of silver-coated copper particles as inexpensive materials has been conducted in recent years.
Patent document 1 discloses the production of silver-coated copper particles using a silver plating solution containing silver, a phosphine compound, a triazole compound and an acidic substance. The silver content of the silver plating solution is 3-10 g/L, the phosphine compound content is 12-40 g/L, the triazole compound content is 0.15-0.5 g/L, and the pH value is 2-4.
Patent document 2 discloses a method in which a molten solution obtained by heating copper and dissolving the molten solution is dropped and high-pressure water is injected to carry out quench solidification to obtain a slurry of copper particles, and the slurry is held in the presence of a non-oxidizing gas such as nitrogen gas and then subjected to solid-liquid separation to obtain copper particles; and coating silver on the copper particles by a reduction method or a substitution method under a non-oxidizing atmosphere.
Patent document 3 discloses that phytic acid having a phosphorus content of 0.01 mass% or less is coated on the surface of silver-coated copper particles.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2017-128788
Patent document 2: japanese patent laid-open No. 2017-190483
Patent document 3: japanese patent application laid-open No. 2015-92017
Disclosure of Invention
However, the techniques described in patent documents 1 and 2 have a problem that the obtained silver-coated copper particles have insufficient oxidation resistance. In addition, the technique described in patent document 3 has a problem that the silver coating reaction itself is hindered by the presence of a surface treatment agent such as phytic acid when forming the silver coating layer, and the formation of the silver coating layer becomes difficult.
Accordingly, the present invention has an object to provide silver-coated copper particles which can easily form a silver coating layer on the surface of copper particles and which have excellent oxidation resistance.
The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that by incorporating phosphorus in a silver coating layer of silver-coated copper particles, the silver coating layer can be stably formed on the surface of copper master batch, and thus have completed the present invention.
Specifically, the present invention provides a method for producing phosphorus-containing silver-coated copper particles having a phosphorus (P) -containing silver coating layer on at least a part of the surface of a copper master batch, wherein a silver compound and phosphoric acid or a salt thereof are co-present in a dispersion of the copper master batch, and a phosphorus-containing silver coating layer is deposited on the surface of the copper master batch.
The present invention also provides a silver-coated copper particle containing phosphorus, which has a silver coating layer containing phosphorus (P) element on at least a part of the surface of a copper master batch,
The oxygen increase (mass%) after 7 days at 85℃and 85% RH storage was defined as I O,
The content ratio (mass%) of silver (Ag) element contained in the phosphor-containing silver-coated copper particles was set to W Ag,
When the content ratio (mass ppm) of the phosphorus (P) element contained in the phosphorus-containing silver-coated copper particles is W P,
I O 2/(WAg×WP). Times.1000 is 1.9 or less.
Detailed Description
The present invention will be described below based on preferred embodiments.
In the production method of the present invention, as a method of coating silver on the surface of the copper master batch, a substitution method using a substitution reaction between copper and silver due to a difference in ionization tendency, and a reduction method using a reducing agent can be used to produce target phosphorus-containing silver-coated copper particles. In particular, when the substitution method is used, phosphorus (P) element can be smoothly introduced into the silver coating layer, and silver-coated copper particles having high oxidation resistance can be obtained.
In the present production method, a dispersion of copper master batch (hereinafter, may be simply referred to as "dispersion") is prepared regardless of whether the substitution method or the reduction method is employed.
The average particle diameter of the copper master batch is preferably 0.1 μm or more and 50 μm or less, more preferably 1 μm or more and 10 μm or less. When the particle diameter of the copper master batch is in the above range, phosphorus-containing silver-coated copper particles excellent in handleability and oxidation resistance can be obtained. The average particle diameter is a volume cumulative particle diameter D 50 at 50% by volume of the cumulative volume measured by the laser diffraction scattering particle size distribution measurement method.
The shape of the copper master batch is not necessarily spherical, and any shape such as a flat shape, a polygonal shape, or a concave-convex shape may be used.
The method for producing the copper master batch is not particularly limited, and may be produced by any method such as atomization, wet reduction, or electrolysis.
Examples of the solvent used for preparing the dispersion include, but are not limited to, water, chloroform, methanol, ethanol, propanol, isopropyl alcohol, butanol, alcohols such as ethylene glycol, propylene glycol, glycerol, and dimethyl sulfoxide (DMSO).
Whether a substitution method or a reduction method is adopted, ethylenediamine tetraacetic acid (EDTA), hydrazine, sulfuric acid or hydrochloric acid can be added for removing the oxide film on the surface of the copper master batch.
The copper master batch is washed by replacing the copper master batch with the same solvent as the solvent contained in the dispersion, and the oxide film in the dispersion is removed by washing, thereby preparing a dispersion in which the copper master batch is dispersed again.
In order to form the silver coating layer more uniformly, a chelating agent may be added to the dispersion liquid, regardless of whether the substitution method or the reduction method is used. As the chelating agent, a chelating agent having a high stability constant against complexation of copper ions or the like is preferably used in order to prevent re-precipitation of copper ions or the like, which are by-produced by substitution reaction of silver ions with metallic copper. In particular, since copper is the main constituent material of the copper master batch which is the core of the silver-coated copper particle, the chelating agent is preferably selected with attention paid to the complexation stability constant with copper. Specifically, as the chelating agent, a chelating agent selected from the group consisting of ethylenediamine tetraacetic acid (EDTA), iminodiacetic acid, diethylenetriamine, triethylenediamine, and salts thereof can be used.
When the substitution method is employed, a solution containing a silver compound and a solution containing phosphoric acid or a salt thereof may be separately prepared, and each of them may be introduced into the dispersion liquid at the same time or separately and allowed to coexist in the dispersion liquid. Alternatively, a plating solution containing a silver compound and phosphoric acid or a salt thereof may be prepared in advance, and the plating solution may be introduced into a dispersion so that the silver compound and phosphoric acid or a salt thereof coexist in the dispersion. Thereby, the copper of the copper master batch in the dispersion liquid and the silver of the silver compound undergo a substitution reaction. At the same time, during the substitution reaction, phosphorus is introduced into the silver coating layer in the process of formation. As a result, phosphorus-containing silver-coated copper particles in which a phosphorus-containing silver-coated layer is formed can be obtained. Thus, a silver-coated layer can be stably obtained, and further, phosphor-containing silver-coated copper particles excellent in oxidation resistance can be obtained.
As the silver compound, a commonly used water-soluble silver salt can be used. Specifically, silver salts such as silver nitrate, silver oxide, silver sulfate, silver acetate, and silver carbonate are mentioned, but the present invention is not limited thereto.
The phosphoric acid is preferably orthophosphoric acid. Examples of the phosphate include disodium hydrogen phosphate, diammonium hydrogen phosphate, dipotassium hydrogen phosphate, and the like, which are salts of orthophosphoric acid, but are not limited thereto.
When the substitution method is used, the ratio of the amount of phosphorus to the amount of silver (mass%) added in the dispersion liquid in which the silver compound and phosphoric acid or a salt thereof coexist is preferably 0.1 to 50, more preferably 0.2 to 30. Thus, the oxidation resistance of the silver-coated layer can be improved, and the oxidation resistance of the target phosphorus-containing silver-coated copper particles can be further improved. "silver addition amount (mass%)" means a ratio of the mass of the silver element in the dispersion to the mass of the copper master batch (for example, when the silver element is 15g, the silver addition amount is 3 mass% with respect to 500g of the copper master batch). "phosphorus addition amount (mass%)" means a ratio of the mass of the phosphorus element in the dispersion to the mass of the silver element (for example, when the phosphorus element is 2.16g, the phosphorus addition amount is 14.4 mass% with respect to 15g of the silver element). For example, when the silver addition amount is 3 mass% and the phosphorus addition amount is 14.4 mass%, the ratio of the phosphorus addition amount (mass%) to the silver addition amount (mass%) is 4.80.
The amount of the silver compound in the dispersion liquid in which the silver compound and phosphoric acid or a salt thereof coexist is preferably 0.1g/L or more and 50g/L or less, more preferably 1g/L or more and 30g/L or less, and still more preferably 1g/L or more and 10g/L or less in terms of silver.
The total amount of phosphoric acid or a salt thereof in the dispersion liquid in which the silver compound and phosphoric acid or a salt thereof coexist is preferably 0.01g/L or more and 50g/L or less, more preferably 0.01g/L or more and 20g/L or less, and still more preferably 0.01g/L or more and 10g/L or less in terms of phosphorus.
The pH of the dispersion liquid in which the silver compound and phosphoric acid or a salt thereof coexist is preferably 5 or more and 10 or less, more preferably 6 or more and 9.5 or less. Thus, a silver coating layer containing phosphorus element can be formed well on the surface of the copper master batch.
The pH of the dispersion in which the silver compound and phosphoric acid or a salt thereof coexist is adjusted by adding an acidic substance or a basic substance to the dispersion as appropriate. For example, an alkaline substance such as sodium hydroxide is added to appropriately adjust the pH. The pH is a value at a temperature at which a silver compound and phosphoric acid or a salt thereof coexist to prepare a dispersion.
When the silver coating layer is formed in a state where the copper master batches are in contact with each other, a block in which a plurality of copper master batches are bonded via the silver coating layer will be formed. The silver-coated copper particles containing phosphorus thus produced are not suitable for use as wiring materials and the like. Therefore, it is preferable to prevent sedimentation of the particles before the silver coating is completed by the substitution reaction. For this purpose, it is preferable to stir the dispersion liquid in which the silver compound and phosphoric acid or a salt thereof coexist and flow the mixture. Stirring is usually performed using stirring blades, but other known stirring methods may be used.
The reaction time of the substitution reaction also depends on the temperature of the dispersion, and is, for example, 5 minutes to 60 minutes.
After the silver-coated copper particles containing phosphorus are produced in this manner, the solvent in the dispersion containing the copper particles is replaced with a solvent such as water, chloroform, alcohol, or Dimethylsulfoxide (DMSO) and washed. Examples of the alcohol include methanol, ethanol, propanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, and glycerin.
When the reduction method is used instead of the substitution method, a reducing agent for silver is introduced into the dispersion of copper master batch, and then a plating solution containing a silver compound and phosphoric acid or a salt thereof is introduced. The plating solution may contain various plating solution components as needed. Thereby, the silver compound in the dispersion is reduced, and the phosphorus element is introduced into the reduced silver, thereby forming a silver coating layer containing phosphorus on at least a part of the surface of the copper master batch. Thereby, silver-coated copper particles containing phosphorus, in which a silver-coated layer containing phosphorus is formed, can be obtained. Thus, a silver-coated layer can be stably obtained, and further, phosphor-containing silver-coated copper particles excellent in oxidation resistance can be obtained.
Examples of the reducing agent for silver include lithium aluminum hydroxide, sodium amalgam, sodium borohydride, sulfate, sulfite, hydrazine, zinc amalgam, diisobutylaluminum hydride, sodium amalgam, sodium borohydride, and oxalic acid.
When the reduction method is employed, the silver compound and phosphoric acid or a salt thereof may be used as the same substances as those described in the substitution method. The silver compound-containing solution and the phosphoric acid-containing solution or a salt thereof may be the same as those described in the substitution method. The solvent constituting the solution containing the silver compound and the plating solution containing phosphoric acid or a salt thereof may be the same solvent as described in the substitution method.
The pH of the plating solution is preferably 5 to 10, more preferably 6 to 9.5. Thus, a silver coating layer containing phosphorus element can be formed well on the surface of the copper master batch. The pH of the plating solution is the value at the temperature at which the dispersion and the plating solution are mixed.
The pH of the plating solution containing the reducing agent is adjusted by appropriately adding an acidic substance and a basic substance. For example, an alkaline substance such as sodium hydroxide is added to appropriately adjust the pH.
The ratio of the amount of phosphorus element (mass%) to the amount of silver element (mass%) added in the dispersion after the plating solution is introduced is preferably 1 to 150, more preferably 1 to 120, still more preferably 1 to 100, and still more preferably 1 to 50. Thus, the oxidation resistance of the silver-coated layer can be improved, and the oxidation resistance of the target phosphorus-containing silver-coated copper particles can be further improved. "silver addition amount (mass%)" means a ratio of the mass of the silver element in the dispersion to the mass of the copper master batch (for example, when the silver element is 15g, the silver addition amount is 3 mass% with respect to 500g of the copper master batch). "phosphorus addition amount (mass%)" means a ratio of the mass of the phosphorus element in the dispersion to the mass of the silver element (for example, when the phosphorus element is 2.16g, the phosphorus addition amount is 14.4 mass% with respect to 15g of the silver element). For example, when the silver addition amount is 3 mass% and the phosphorus addition amount is 14.4 mass%, the ratio of the phosphorus addition amount (mass%) to the silver addition amount (mass%) is 4.80.
Specifically, the amount of the silver compound in the dispersion after the plating solution is introduced is preferably 0.1g/L or more and 50g/L or less, more preferably 0.1g/L or more and 20g/L or less, and still more preferably 0.1g/L or more and 10g/L or less in terms of silver.
The total amount of phosphoric acid or a salt thereof in the dispersion is preferably 0.1g/L or more and 50g/L or less, more preferably 1g/L or more and 30g/L or less in terms of phosphorus.
In the case of the reduction method, similarly to the substitution method, when the silver coating layer is formed in a state where the copper master batches are in contact with each other, a block in which a plurality of copper master batches are bonded via the silver coating layer is formed. The silver-coated copper particles containing phosphorus thus produced are not suitable for use as wiring materials and the like. Therefore, it is preferable to prevent sedimentation of the particles before the silver coating is completed by the reduction reaction of silver. For this purpose, it is preferable to stir the dispersion liquid in which the silver compound and phosphoric acid or a salt thereof coexist and flow the mixture. Stirring is usually performed using stirring blades, but other known stirring methods may be used.
The reaction time of the reduction reaction also depends on the temperature of the dispersion containing the plating solution, and is, for example, 5 minutes to 60 minutes.
After the silver-coated copper particles containing phosphorus are obtained by either the displacement method or the reduction method, the silver-coated copper particles containing phosphorus are separated and removed from the dispersion liquid by a solid-liquid separation method such as vacuum dehydration, press filtration, centrifugal separation, ultrafiltration and the like. The phosphorus-containing silver-coated copper particles are then washed with a solvent. Thus, a silver coating layer containing phosphorus is deposited on the surface of the copper master batch.
In view of the convenience of handling the powder, the surface treatment may be performed on the phosphor-containing silver-coated copper particles as needed after cleaning the phosphor-containing silver-coated copper particles. The surface treatment agent is not particularly limited, and may be appropriately selected according to the purpose. Examples of the surface treatment agent include fatty acids, fatty acid salts, surfactants, organometallic compounds, chelating agents, and polymeric dispersants.
In the silver-coated copper particles containing phosphorus obtained as described above, phosphorus element is contained in the silver coating layer disposed on at least a part of the copper master batch due to the production method thereof. The phosphorus-containing silver-coated copper particles of the present invention have high oxidation resistance due to such a structure. From the standpoint of cost, it is generally required to reduce the content of silver in the silver-coated copper particles. However, if the content of silver is reduced, the copper particles become exposed at a larger portion not covered with the silver coating layer, and copper that is more easily oxidized than silver is exposed, and oxidation resistance of the silver-coated copper particles tends to be reduced. On the other hand, according to the above-mentioned silver-coated copper particles containing phosphorus, although the mechanism is not necessarily clear, it is considered that the coating property of the copper particles coated with the silver coating layer containing phosphorus is improved compared with the coating layer composed of only silver by the action of the phosphorus element contained in the silver coating layer, and thus the oxidation resistance of the silver-coated copper particles containing phosphorus is excellent.
On the other hand, as shown in comparative example 2 described below, the silver coating layer was disposed on the surface of the copper master, and when the phosphorus element was present on the silver coating layer (in other words, when the phosphorus element was not present in the silver coating layer), the oxidation resistance was not sufficiently exhibited.
From the viewpoint of improving oxidation resistance, the silver coating layer preferably covers the entire surface of the copper master batch. However, the silver coating layer may also cover a part of the surface of the copper master batch as long as it exhibits the desired oxidation resistance.
The form of the phosphorus element contained in the silver coating layer is not particularly limited. The inventors considered that the fragments of PO 3、PO2 were observed from analysis of silver-coated copper particles containing phosphorus by TOF-SIMS, and considered that the phosphorus element was present in the state of phosphorus oxide, for example, in the state of PO 4 3- ions.
The oxidation resistance of the phosphorus-containing silver-coated copper particles of the present invention can be evaluated using the oxidation resistance index OR as an index. The oxidation resistance index OR is defined by the following formula (1).
Oxidation resistance index or=i O 2/(WAg×WP) ×1000 (1)
In formula (1), I O is the oxygen increase (mass%) after 7 days when the silver-coated copper particles containing phosphorus are stored at 85 ℃ and 85% rh. I O is defined by I O＝I2-I1. I 2 is the oxygen content (mass%) after 7 days when the silver-coated copper particles containing phosphorus are stored at 85 ℃ and 85% rh, and I 1 is the oxygen content (mass%) before storage.
W Ag is the content (mass%) of silver (Ag) element contained in the phosphorus-containing silver-coated copper particles.
W P is the content ratio (mass ppm) of phosphorus (P) element contained in the silver-coated copper particles containing phosphorus.
The technical meaning of formula (1) is as follows. The molecule I O in formula (1) reflects the extent of oxidation of the silver-coated copper particles containing phosphorus. The square of I O is to amplify the oxidation degree numerically even in the case where the oxidation degree is small. Here, I O is an index of the oxidation degree of the silver-coated copper particles, and may be used as an index indirectly indicating the coating rate of the silver coating layer (the area ratio of the surface of the silver-coated copper particles) in the silver-coated copper particles. The coating rate of the silver-coated layer is difficult to quantitatively observe by surface observation or the like of the silver-coated copper particles. Accordingly, the present inventors have focused on the characteristics of silver-coated copper particles (i.e., the characteristics that the more the copper particles are not coated with the silver coating layer, the more easily they are oxidized and the larger the value of I O), and used I O as an index indirectly indicating the coating rate of the silver coating layer.
The denominator W Ag×WP of formula (1) reflects the amounts of elemental silver and elemental phosphorus present in the phosphorus-containing silver-coated copper particles. The higher the amounts of silver element and phosphorus element present in the phosphorus-containing silver-coated copper particles, the higher the coating rate of the copper particles with the silver coating layer in the phosphorus-containing silver-coated copper particles, and thus the oxygen increasing amount I O tends to decrease. Thus, the degree of increase in the oxygen increase I O is normalized by dividing the square of I O by W Ag×WP. Thus, a smaller value of oxidation resistance index OR means that the silver-coated copper particles containing phosphorus are more difficult to oxidize.
The multiplication of 1000 in the formula (1) is because the value of I O 2/(WAg×WP) is very small and difficult to handle, and thus the multiplication of 1000 makes it an easy-to-handle value.
The oxidation resistance index OR of the phosphorus-containing silver-coated copper particles of the present invention is preferably 1.9 OR less, more preferably 1.0 OR less, and still more preferably 0.5 OR less. Phosphor-containing silver-coated copper particles having such an oxidation resistance index OR are extremely difficult to oxidize.
The oxidation resistance index OR of the phosphorus-containing silver-coated copper particles of the present invention is, as described above, preferably 1.0 mass% OR less, more preferably 0.8 mass% OR less, even more preferably 0.6 mass% OR less, still more preferably 0.4 mass% OR less, and particularly preferably 0.2 mass% OR less of the oxygen increase amount I O after 7 days of storage at 85 ℃ and 85% rh. The method for measuring the oxygen increase amount I O is described in examples described later.
The content ratio W Ag of the silver element contained in the phosphorus-containing silver-coated copper particles of the present invention is preferably 0.1 mass% or more from the viewpoint of improving the oxidation resistance of the phosphorus-containing silver-coated copper particles. In order to make this advantage more remarkable, the content ratio W Ag of the silver element is more preferably 1 mass% or more, still more preferably 2 mass% or more, and still more preferably 3 mass% or more.
In view of the balance between improving the oxidation resistance of the phosphorus-containing silver-coated copper particles and the economical efficiency of using a silver element as a high-valence element, the content ratio W Ag of the silver element is preferably 30 mass% or less, more preferably 20 mass% or less, and still more preferably 10 mass% or less.
The phosphorus element content W P in the phosphorus-containing silver-coated copper particles of the present invention is preferably 50 mass ppm or more from the viewpoint of improving the oxidation resistance of the phosphorus-containing silver-coated copper particles. In order to make this advantage more remarkable, the content ratio W P of the phosphorus element is more preferably 70 mass ppm or more, and still more preferably 80 mass ppm or more.
The phosphorus element content W P is preferably 5000 mass ppm or less, more preferably 3000 mass ppm or less, further preferably 500 mass ppm or less, and further preferably 300 mass ppm or less, from the viewpoint of improving the oxidation resistance of the silver-coated copper particles containing phosphorus and ensuring the balance of conductivity.
The method for measuring the content ratio W Ag of the silver element and the content ratio W P of the phosphorus element is described in examples described later.
As described above, since the phosphorus-containing silver-coated copper particles of the present invention have high oxidation resistance, the increase in resistance can be suppressed even when the copper particles are placed in an oxidizing environment. Specifically, the increase rate I R of the volume resistivity after 7 days when the phosphorus-containing silver-coated copper particles of the present invention are stored at 85 ℃ and in an environment of 85% rh is preferably 532% or less, more preferably 500% or less, further preferably 300% or less, and still further preferably 100% or less.
When the initial volume resistivity was R 1 (Ω cm) and the volume resistivity after 7 days at 85 ℃ and 85% rh was R 2 (Ω cm), the rate of increase I R of the volume resistivity was defined by (R 2-R1)/R1 ×100).
The volume resistivity R 2 after 7 days at 85℃and 85% RH is preferably 9.9X10- -3. OMEGA.cm or less, more preferably 9.9X10- -4. OMEGA.cm or less.
The method for measuring the volume resistivity is described in examples described below.
The oxidation resistance of copper particles also depends on their particle size, and the smaller the particle size, the larger the specific surface area, and thus is easily oxidized. From this point of view, the volume cumulative particle diameter D 50 of the phosphorus-containing silver-coated copper particles of the present invention at 50% by volume of the cumulative volume measured by the laser diffraction scattering particle size distribution measurement method is preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 15 μm or less, and still more preferably 1 μm or more and 10 μm or less.
The method for measuring the particle diameter D 50 will be described later.
Regarding the above particle diameter D 50, the BET specific surface area of the phosphorus-containing silver-coated copper particles of the present invention is preferably 0.1m 2/g or more and 10m 2/g or less, more preferably 0.1m 2/g or more and 5m 2/g or less, still more preferably 0.1m 2/g or more and 3m 2/g or less, from the viewpoint of oxidation resistance.
The method for measuring the BET specific surface area will be described later.
Examples
[ Evaluation ]
(1) Compositional analysis of silver-coated copper particles containing phosphorus
The sample powder was dissolved by wet decomposition with nitric acid, the concentrations of silver and phosphorus were measured by an ICP emission spectrometer, and the content ratio W Ag、WP of elemental silver and elemental phosphorus in the powder was calculated from the concentrations.
(2) Oxygen increase I after 7 days at 85℃and 85% RH storage O
The sample was placed in a graphite crucible, and then heated and melted under an atmosphere of He using EMGA-820ST manufactured by horiba, inc. The carbon monoxide (carbon dioxide) thus produced was measured by a non-dispersive infrared absorption method, and the initial oxygen content I 1 (mass%) was measured.
The difference between the initial oxygen content I 1 and the oxygen content I 2 after cooling to room temperature after maintaining the measurement sample in a high-temperature humidifier at 85 ℃ and 85% RH for 7 days was obtained to obtain an oxygen increase I O after 7 days. Specifically, the oxygen increase amount I O was obtained by subtracting the initial oxygen content I 1(I2-I1) from the oxygen content I 2 after 7 days.
(3) Volume resistivity R 1, volume resistivity R 2 after 7 days at 85 ℃ and 85% RH storage, and volume resistivity increase rate I R
After being kept in a high-temperature humidifier at 85 ℃ and 85% RH for 7 days, 5g of the sample cooled to normal temperature was placed in a tubular container, and compression molding was performed under a pressurizing pressure of 31.83MPa to form a measurement sample. The volume resistivity R 2 was measured using the measurement sample. The volume resistivity R 2 was measured using Loresta AP and Loresta PD-41 (both manufactured by Mitsubishi chemical Co., ltd.). The volume resistivity R 1 before storage was also measured by the same method. Then, based on the volume resistivity R 1 and the volume resistivity R 2, the rate of increase I R in the volume resistivity was obtained by the above method.
(4) BET specific surface area
The amount of the measurement sample was set to 0.3g, and the measurement was performed by the BET single point method using Monosorb manufactured by Mountech Co., ltd.
(5) Particle diameter D 50
0.2G of the measurement sample was placed in a beaker, and 0.07gTriton X-100 (manufactured by Kanto chemical Co., ltd.) was added. Next, the sample was put into 40mL of water (dispersant: 0.3% SN-PW-43 solution (sannopco)), and then dispersed by applying ultrasonic waves of 300watts for 3 minutes using an ultrasonic disperser US-300AT (manufactured by Japanese refiner). The volume cumulative particle diameter D 50 was measured using a laser diffraction scattering particle size distribution measuring apparatus MT3300II (daily machine) for the measurement sample.
(6) Oxidation resistance OP
The oxidation resistance OP defined by the following formula (1) was calculated using the rate of increase I R (%) of the volume resistivity calculated from the volume resistivity R 1 and R 2, the BET specific surface area SSA (m 2/g), and the phosphorus content ratio W P (mass ppm).
Oxidation resistance op=rate of increase of volume resistivity I R(％)/(SSA(m2/g)×WP (mass ppm)
The oxidation resistance OP is a value obtained by normalizing the rate of increase in volume resistivity I R to the specific surface area and the phosphorus content, and is a parameter indicating the difficulty of oxidation of the particles. The smaller this value means that the silver-coated copper particles containing phosphorus are more difficult to oxidize.
Example 1
After 26g of ethylenediamine tetraacetic acid (EDTA) was dissolved in 5L of pure water and the liquid temperature was adjusted to 40 ℃, 500g of copper master batch (1) (spherical, average particle diameter D 50 =1.5 μm, manufactured by mitsubishi metal mining corporation) was added and stirred to prepare a copper master batch dispersion. Then, 10L of pure water was used for stirring the copper master batch dispersion, and the copper master batch was cleaned by decantation. A silver salt solution in which silver nitrate containing 15g of silver was dissolved in 1.2L of pure water and a phosphate solution in which disodium hydrogen phosphate 12 hydrate containing 2.2g of phosphorus was dissolved in 1.2L of pure water were prepared.
Subsequently, the dispersion was kept at 40℃with a pure water amount of 5L, and the silver salt solution, the phosphate solution and 35g of EDTA were added to the dispersion while stirring, and silver coating reaction was performed for 30 minutes. Pure water was added to the obtained dispersion of silver-coated copper particles containing phosphorus, and after stirring and washing, the mixture was decanted, the washing liquid was separated and removed, and then alcohol substitution was performed, and then fatty acid treatment was performed to prevent aggregation, and drying was performed, to obtain silver-coated copper particles containing phosphorus (see table 1).
The composition of the obtained silver-coated copper particles containing phosphorus, the initial oxygen increment I 1, the volume resistivity R 1, the oxygen-containing rate I 2 after 7 days at 85 ℃ and 85% rh storage, the oxygen increment I 0, the volume resistivity R 2, and the volume resistivity increment I R were measured based on the above evaluation method. The results are shown in Table 2.
Example 2
Silver-coated copper particles containing phosphorus were produced in the same manner as in example 1, except that the phosphorus content in the phosphate solution was set to 6.5 g.
The composition of the obtained silver-coated copper particles containing phosphorus, the initial oxygen increment I 1, the volume resistivity R 1, the oxygen-containing rate I 2 after 7 days at 85 ℃ and 85% rh storage, the oxygen increment I 0, the volume resistivity R 2, and the volume resistivity increment I R were measured based on the above evaluation method. The results are shown in Table 2.
Example 3
Phosphor-containing silver-coated copper particles were produced in the same manner as in example 1, except that copper master (2) (dendrite, average particle diameter D 50 =7 μm, manufactured by Mitsui metal mining Co., ltd.) was used instead of copper master (1).
The composition of the obtained silver-coated copper particles containing phosphorus, the initial oxygen increment I 1, the volume resistivity R 1, the oxygen-containing rate I 2 after 7 days at 85 ℃ and 85% rh storage, the oxygen increment I 0, the volume resistivity R 2, and the volume resistivity increment I R were measured based on the above evaluation method. The results are shown in Table 2.
Example 4
Phosphor-containing silver-coated copper particles were produced in the same manner as in example 1, except that copper master batch (3) (spherical, average particle diameter D 50 =2 μm, manufactured by Mitsui metal mining Co., ltd.) was used instead of copper master batch (1).
The composition of the obtained silver-coated copper particles containing phosphorus, the initial oxygen increment I 1, the volume resistivity R 1, the oxygen-containing rate I 2 after 7 days at 85 ℃ and 85% rh storage, the oxygen increment I 0, the volume resistivity R 2, and the volume resistivity increment I R were measured based on the above evaluation method. The results are shown in Table 2.
Example 5
After 47g of ethylenediamine tetraacetic acid (EDTA) was dissolved in 5L of pure water, 400g of copper master batch (1) (spherical, average particle diameter D 50 =1.5 μm, manufactured by mitsubishi metal mining corporation) was added thereto and stirred to prepare a copper master batch dispersion. Then, 10L of pure water was used for stirring the copper master batch dispersion, and the copper master batch was cleaned by decantation. To the dispersion in which 5L of pure water was added to the copper master batch after washing, 19g of hydrazine was added as a reducing agent.
Separately from this operation, the following plating solutions were prepared: in 2L of pure water, silver nitrate containing 16g of silver and disodium hydrogen phosphate 12 hydrate containing 13g of phosphorus were contained, and further 6g of ethylene glycol as a surfactant, 108g of 5, 5-dimethylhydantoin as a complex forming substance, and a pH was adjusted to 9.1 using an aqueous sodium hydroxide solution as a pH adjuster.
When the plating solution was stirred and maintained at 40 ℃, the dispersion was poured, and as a result, the change in white color of the dispersion was confirmed to be gradually stronger. After the change in the liquid color was sufficiently observed, stirring was stopped to produce silver-coated copper particles containing phosphorus.
Pure water was added to the obtained dispersion containing phosphorus-containing silver-coated copper particles, and the mixture was stirred and washed, followed by decantation to remove the washing liquid. Alcohol displacement is then performed. Next, in order to prevent aggregation, fatty acid treatment was performed, and then drying was performed, thereby obtaining silver-coated copper particles containing phosphorus.
The composition of the obtained silver-coated copper particles containing phosphorus, the initial oxygen increment I 1, the volume resistivity R 1, the oxygen-containing rate I 2 after 7 days at 85 ℃ and 85% rh storage, the oxygen increment I 0, the volume resistivity R 2, and the volume resistivity increment I R were measured based on the above evaluation method. The results are shown in Table 2.
Example 6
A phosphorus-containing silver-coated copper particle was produced in the same manner as in example 1, except that the time for carrying out the silver-coating reaction was set to 60 minutes, and the same measurement as in this example was carried out. The results are shown in Table 2.
Example 7
A phosphorus-containing silver-coated copper particle was produced in the same manner as in example 4, except that a silver salt solution in which 100g of silver nitrate was dissolved in 4.8L of pure water and a phosphate solution in which 4.0g of phosphorus-containing disodium hydrogen phosphate 12 hydrate was dissolved in 1.2L of pure water were prepared, and the same measurement as in this example was performed. The results are shown in Table 2.
Example 8
A phosphorus-containing silver-coated copper particle was produced in the same manner as in example 4, except that a silver salt solution in which 200g of silver nitrate was dissolved in 4.8L of pure water and a phosphate solution in which 4.0g of phosphorus-containing disodium hydrogen phosphate 12 hydrate was dissolved in 1.2L of pure water were prepared, and the same measurement as in this example was performed. The results are shown in Table 2.
Example 9
A silver-coated copper particle containing phosphorus was produced in the same manner as in example 7, except that copper master batch (4) (sheet-like, average particle diameter D 50 =7.5 μm) was used instead of copper master batch (1), and the same measurement as in this example was performed. The results are shown in Table 2.
Example 10
A silver-coated copper particle containing phosphorus was produced in the same manner as in example 8, except that copper master batch (4) (sheet-like, average particle diameter D 50 =7.5 μm) was used instead of copper master batch (1), and the same measurement as in this example was performed. The results are shown in Table 2.
Comparative example 1
Silver-coated copper particles were produced in the same manner as in example 1, except that the phosphate solution was not added.
The composition of the silver-coated copper particles, the initial oxygen increment I 1, the volume resistivity R 1, the oxygen content I 2 after 7 days at 85 ℃ and 85% rh storage, the oxygen increment I 0, the volume resistivity R 2, and the volume resistivity increment I R were measured based on the above evaluation method. The results are shown in Table 2.
Comparative example 2
A copper master batch dispersion in which copper master batches (spherical, average particle diameter D 50 =1.5 μm, manufactured by mitsubishi metal mining corporation) were dispersed in pure water was kept at 40 ℃, and the silver salt solution and EDTA were added to the dispersion while stirring, and silver coating reaction was performed for 30 minutes. To the silver-coated copper particle dispersion obtained, 0.09g of phytic acid was added and stirred for 5 minutes to prepare silver-coated copper particles containing phytic acid. The silver phytate-containing coated copper particles were washed with 10L of pure water, decanted, and the washing liquid was removed. Then, alcohol substitution was performed. Next, in order to prevent aggregation, fatty acid treatment was performed, and then drying was performed, thereby obtaining silver phytate-containing coated copper particles.
The composition of the obtained silver-coated copper particles containing phosphorus, the initial oxygen increment I 1, the volume resistivity R 1, the oxygen-containing rate I 2 after 7 days at 85 ℃ and 85% rh storage, the oxygen increment I 0, the volume resistivity R 2, and the volume resistivity increment I R were measured based on the above evaluation method. The results are shown in Table 2.
Comparative example 3
Silver-coated copper particles were produced in the same manner as in example 9, except that the phosphate solution was not added, and the same measurement as in this example was performed. The results are shown in Table 2.
Comparative example 4
Silver-coated copper particles were produced in the same manner as in example 10, except that the phosphate solution was not added, and the same measurement as in this example was performed. The results are shown in Table 2.
TABLE 1
TABLE 2
As is clear from table 2, according to the present invention, the oxidation resistance index OR of the silver-coated copper particles containing phosphorus, which are obtained by allowing the silver compound and phosphoric acid OR a salt thereof to coexist in the dispersion of the copper master batch, to form the silver-coated layer containing phosphorus on the surface of the copper master batch, was suppressed to a low value.
On the other hand, in comparative examples 1, 3 and 4, since the silver coating layer formed on the surface of the copper master batch did not contain phosphorus, the oxidation resistance of the silver coating layer, and thus the silver-coated copper particles, was lowered, and the oxidation resistance index OR was high. In particular, in comparative examples 3 and 4, the oxidation resistance index OR was high although the silver content W Ag was as high as 10.1 mass% and 20.0 mass%, respectively.
In comparative example 2, the silver-coated copper particles containing phytic acid were added with phytic acid dispersed in pure water after the silver coating layer was formed, and therefore, it was considered that the silver coating layer did not contain phosphorus. From this, it is found that the oxidation resistance index OR is a high value.
Industrial applicability
According to the present invention, it is possible to provide silver-coated copper particles which can easily form a silver coating layer on the surface of copper particles and which are excellent in oxidation resistance.
Claims (10)
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2022033732 | 2022-03-04 | ||
| JP2022-033732 | 2022-03-04 | ||
| PCT/JP2023/007914 WO2023167302A1 (en) | 2022-03-04 | 2023-03-02 | Method for manufacturing phosphorus-containing-silver-coated copper particles, and phosphorus-containing-silver-coated copper particles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118055817A true CN118055817A (en) | 2024-05-17 |
Family
ID=87883795
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202380013869.7A Pending CN118055817A (en) | 2022-03-04 | 2023-03-02 | Method for producing phosphorus-containing silver-coated copper particles and phosphorus-containing silver-coated copper particles |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP7614381B2 (en) |
| CN (1) | CN118055817A (en) |
| TW (1) | TW202402424A (en) |
| WO (1) | WO2023167302A1 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06240463A (en) * | 1993-02-22 | 1994-08-30 | Mitsubishi Paper Mills Ltd | Method for electroless-plating fine metal powder with silver |
| JP4864195B2 (en) * | 2000-08-30 | 2012-02-01 | 三井金属鉱業株式会社 | Coated copper powder |
| CN104321464A (en) | 2011-12-15 | 2015-01-28 | 汉高知识产权控股有限责任公司 | Selective coating of exposed copper on silver-plated copper |
| JP6389091B2 (en) | 2013-10-01 | 2018-09-12 | Ｄｏｗａエレクトロニクス株式会社 | Silver-coated copper powder, method for producing the same, and conductive paste |
-
2023
- 2023-03-02 WO PCT/JP2023/007914 patent/WO2023167302A1/en not_active Ceased
- 2023-03-02 JP JP2023548575A patent/JP7614381B2/en active Active
- 2023-03-02 CN CN202380013869.7A patent/CN118055817A/en active Pending
- 2023-03-03 TW TW112107892A patent/TW202402424A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| TW202402424A (en) | 2024-01-16 |
| WO2023167302A1 (en) | 2023-09-07 |
| JP7614381B2 (en) | 2025-01-15 |
| JPWO2023167302A1 (en) | 2023-09-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1950162B (en) | Flake copper powder, manufacturing method thereof, and conductive paste | |
| US11424049B2 (en) | Spherical silver powder and method for producing same | |
| JP5820202B2 (en) | Copper powder for conductive paste and method for producing the same | |
| JP5068614B2 (en) | Method for producing copper nanoparticles using microwaves | |
| KR20080100365A (en) | Fine silver particle manufacturing method and fine silver particle obtained by the manufacturing method | |
| JP5926322B2 (en) | Coated copper particles and method for producing the same | |
| KR101525099B1 (en) | Metal microparticle containing composition and process for production of the same | |
| US20100243967A1 (en) | Composition containing fine silver particles, production method thereof, method for producing fine silver particles, and paste having fine silver particles | |
| JP5142891B2 (en) | Cuprous oxide powder and method for producing the same | |
| JP6033485B2 (en) | Coated copper particles | |
| JP2013541640A (en) | Silver particles and method for producing the same | |
| TWI273936B (en) | Slurry of ultrafine copper powder and method for producing the slurry | |
| CN101011747A (en) | Method of producing copper powder and copper powder | |
| CN118055817A (en) | Method for producing phosphorus-containing silver-coated copper particles and phosphorus-containing silver-coated copper particles | |
| JP2014091842A (en) | Method of manufacturing silver coating copper alloy powder | |
| JP6031571B2 (en) | Copper powder for conductive paste and method for producing the same | |
| JP6577316B2 (en) | Copper powder for conductive paste and method for producing the same | |
| JP5063624B2 (en) | Method for producing nickel fine particles | |
| JP4012961B2 (en) | Production method of plate copper powder | |
| JP2019186225A (en) | Copper powder for conductive paste and manufacturing method therefor | |
| JP6722495B2 (en) | Silver-coated copper powder and method for producing the same | |
| KR102314912B1 (en) | Method for producing nickel particles | |
| JP2017201062A (en) | Method for producing silver-coated copper alloy powder | |
| JP2018076597A (en) | Silver coated copper powder and conductive paste, as well as production method thereof | |
| TW202339875A (en) | Metal ink, method for manufacturing metal ink, and method for manufacturing metal layer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB02 | Change of applicant information |
Country or region after: Japan Address after: Japan Applicant after: Mitsui Metal Co.,Ltd. Address before: Tokyo, Japan Applicant before: MITSUI MINING & SMELTING Co.,Ltd. Country or region before: Japan |
|
| CB02 | Change of applicant information |