KR20110041432A - Copper powder for conductive paste and conductive paste - Google Patents

Abstract

The copper powder for conductive paste is characterized by containing 0.1 atm% to 10 atm% of Si (silicon) and 0.1 to 10 atm% of In in the particles. It is preferable to contain 0.1 atm%-10atm% of Ag (silver) in particle inside. It is also preferable to contain 0.01 atm%-0.5 atm% of P (phosphorus) in particle inside. It is also preferable that Si / In (atm ratio) is 0.5-5. It is preferable that the copper powder for electrically conductive pastes is manufactured by the atomizing method.

Description

Copper powder for conductive paste and conductive paste {COPPER POWDER FOR CONDUCTIVE PASTE, AND CONDUCTIVE PASTE}

The present invention relates to a copper powder for conductive paste and a conductive paste using the same. The present invention relates in particular to copper powders suitable for forming conductive circuits by screen printing additive processes or to forming various electrical contact members, such as forming external electrodes of multilayer ceramic capacitors, and conductive pastes using the same. will be.

Due to its ease of handling, copper powder has been widely used as a conductive material for forming conductive circuits by screen printing additive method or for forming conductive pastes for forming various external contact members such as external electrodes of multilayer ceramic capacitors. It is used.

The said electrically conductive paste can be obtained by mix | blending and kneading various additives, such as resin, such as an epoxy resin, and its hardening | curing agent, for example in copper powder. The copper powder used is a wet reduction method in which a copper salt is precipitated from a solution containing a copper salt with a reducing agent, a gas phase reduction method in which the copper salt is heated and vaporized to be reduced in the gas phase, and the molten copper foil is inert gas or water. It can be manufactured by an atomization process or the like which is quenched with a coolant to form a powder.

Among the methods for producing copper powder described above, the atomizing method has an advantage that the residual concentration of impurities in the obtained copper powder can be reduced as compared with the wet reduction method which is generally used. Moreover, it also has the advantage that the pore from the surface of the particle | grains of the copper powder obtained to the inside can be reduced. For this reason, when the copper powder manufactured by the atomizing method is used as the electrically conductive material of an electrically conductive paste, there exists an advantage that the gas generation amount at the time of paste hardening can be reduced, and progress of oxidation can be suppressed significantly.

The copper powder is suitable for the conductive material of the conductive paste because of its high conductivity. However, as the particle size becomes finer, there is a drawback that oxidation resistance is poor. In order to improve it, the method of coating the particle | grain surface with silver with oxidation resistance (patent document 1), the method of coating with inorganic oxide (patent document 2), etc. were employ | adopted.

Japanese Patent Laid-Open No. 10-152630 JP 2005-129424 A

Recently, in circuit formation using a conductive paste or the like, further miniaturization of a circuit is required. Inevitably, the particle size of the conductive powder used for the conductive paste is required to be refined. At the same time, in order to ensure the stability and reliability of the paste characteristics, the conductive powder must be small in the shape or particle size variation and not impair the conductivity. And focusing only on the improvement of oxidation resistance, it was possible to respond by techniques, such as patent documents 1 and 2.

However, since the techniques, such as patent documents 1 and 2, depend on coating | covering technique, a large amount of components which deteriorate electroconductivity are required as components other than copper. In addition, the problem arises that the coating peels from the copper particles as the core material. In addition, in order to reduce the variation in shape and particle size, it is desired that the particles to be formed are equally homogeneous and the concentration of oxygen contained is low, and such a copper powder has not yet been found to be satisfactory.

An object of the present invention is to provide a copper paste for conductive paste having excellent oxidation resistance without degrading conductivity and having a fine particle size. Moreover, an object of this invention is to provide the copper powder for electrically conductive pastes with small variation of a shape and a particle size, and with low oxygen concentration.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, when the particle | grain of a copper powder contains a specific amount of Si and In, it discovered that the said subject was solved and completed this invention.

That is, the copper powder for conductive pastes of the present invention is characterized by containing 0.1 atm to 10 atm% of Si and 0.1 to 10 atm% of In in the particles. Another aspect of the present invention is a conductive paste containing the copper powder for conductive paste.

The copper powder for electrically conductive pastes of this invention contains specific component types other than copper in particle | grains, and does not deteriorate electroconductivity, but is excellent in oxidation resistance remarkably, although it is a fine particle size. In addition, since the variation in particle shape and particle size is small and the concentration of oxygen contained is low, the copper powder for the conductive paste of the present invention can be used for the formation of conductor circuits by screen printing additive method or external electrode formation of a multilayer ceramic capacitor. It can be used very favorably as a conductive material for conductive paste for forming various electrical contact members such as for example.

Embodiment of the copper powder for electrically conductive pastes which concerns on this invention is described. However, the scope of the present invention is not limited to the following embodiment.

The copper powder for conductive pastes according to the present invention is characterized by containing 0.1 atm to 10 atm% of Si and 0.1 to 10 atm% of In in the particles.

It is important here not only to contain Si and In, but also to contain a certain amount of Si and In inside the particle. "Inside particle" means the site | part inside of the particle | grain surface.

The copper powder disclosed in the representative prior art including the above patent documents, that is, copper powder coated or adhered to the surface of the copper powder particles, which is a material or compound having a lower conductivity than copper, is effective in improving oxidation resistance. There is. However, such a copper powder does not have the property of pursuing the present invention, that is, the conductivity is fine, the particle size is fine, and the oxidation resistance is excellent.

Si and In components contained in the copper powder for conductive pastes according to the present invention are distributed in the metal phase inside the particles. Particularly preferably, these components are present inside the particles, and are concentrated in the vicinity of the particle surface without being exposed to the particle surface. If the Si and In components are in such a distribution state, in addition to the improvement of oxidation resistance, the advantageous effect that the outstanding electroconductivity can be maintained is exhibited.

When the distribution state described above is described in detail, the above-mentioned "concentration exists in the vicinity of the particle surface" means that the Si and In components do not exist on the surface of the particle, and the region having a predetermined depth from the surface of the particle. It is said to be ubiquitous in. In this case, when the Si and In components are concentrated in the vicinity of the particle surface, the distribution state of the Si component and the distribution state of the In component do not need to coincide. Particularly, it is preferable that Si and In components not be substantially present not only on the surface of the particles, but also on the center region of the particles, in view of further improvement of oxidation resistance and further maintenance of conductivity. The distribution state of the Si and In components in the particles may be, for example, by cutting the surface of the particles with an argon ion sputter or the like and performing elemental analysis on the surface produced by cutting, or by cutting the particles and performing elemental analysis of the cut surface. It can be measured.

Like the copper powder for electrically conductive paste which concerns on this invention, when the Si component and In component are contained together in particle inside, the oxidation resistance in 600 degreeC-800 degreeC can especially be improved remarkably. For example, with the oxidation resistance index of (DELTA) (TG / SSA) mentioned later, 20% / m <2> / cm <3> or less can be implement | achieved at the temperature level of 600 degreeC. Such an advantageous effect is not obtained in the copper powder containing Si component or In component separately.

In the copper powder for conductive pastes according to the present invention, the content of Si is 0.1 atm to 10 atm%, preferably 0.5 atm to 5 atm%, and more preferably 1 to 3 atm%. If this content is less than 0.1 atm%, the effect pursued by this invention cannot be expected. When it exceeds 10 atm%, not only the conductivity is impaired, but also an effect suitable for addition is not obtained.

The content of In is 0.1 atm% to 10 atm%, preferably 0.5 atm% to 5 atm%, and more preferably 1 atm% to 3 atm%. If this content is less than 0.1 atm%, the effect pursued by this invention cannot be expected. When it exceeds 10 atm%, not only the conductivity is impaired, but also an effect suitable for addition is not obtained, and it is uneconomical in terms of manufacturing cost.

In addition to Si and In, the copper powder for conductive pastes according to the present invention preferably contains Ag at 0.1 atm% to 10 atm%, more preferably 0.5 atm to 5 atm%, and most preferably 1 atm to 3 atm. It contains%. When Ag is contained in this specific amount, conductivity can be further improved while maintaining oxidation resistance of the copper powder for conductive paste. Moreover, manufacturing cost is also suppressed. Particularly preferably, Ag is present inside the particles and is concentrated in the vicinity of the particle surface without exposing to the particle surface. Particularly, it is preferable that Ag is not substantially present not only on the surface of the particle but also on the center of the particle, in view of further improvement of oxidation resistance and further maintenance of conductivity. The distribution state of Ag in particle | grains can be measured by the same method as the measuring method of distribution state of Si and In component mentioned above. In addition, the distribution state of Ag does not need to match the distribution state of Si and In.

In addition to Si and In, the copper powder for electrically conductive pastes concerning this invention contains P (phosphorus) in particle inside preferably 0.01 atm%-0.5 atm%, More preferably, 0.05 atm%-0.3 atm%. When P is contained in this specific amount, it becomes a copper paste for conductive paste that is excellent in oxidation resistance and excellent in conductivity even though the particle size is fine. Furthermore, the characteristic that the dispersion | variation in the shape and particle size of particle | grains is small, and the density | concentration of oxygen contained is low improves. In particular, Si and In coexist, so that the effect of improving the oxidation resistance is not impaired even if the concentration of P is high. Particularly preferably, P is present inside the particles and is concentrated in the vicinity of the particle surface without being exposed to the particle surface. In particular, it is preferable from the viewpoint of further improvement of oxidation resistance and the further maintenance of electroconductivity that P does not exist substantially not only in the surface of a particle but also in the center region of a particle | grain. The distribution state of P in particle can be measured by the same method as the measuring method of distribution state of Si and In component mentioned above. In addition, the distribution state of Ag does not need to match the distribution state of Si and In.

When the copper paste for conductive paste according to the present invention contains all of Si, In, Ag, and P, in spite of its fine particle size, the particle shape and particle size variation are small and the oxidation resistance is remarkably excellent. This further improves.

In the copper powder for electrically conductive pastes concerning this invention, the ratio of Si, In, Ag, and P contained in this is measured by the method as described in the Example mentioned later.

The copper powder for the conductive paste according to the present invention preferably has a Si / In (atm ratio) of 0.5 to 5, more preferably 1 to 4. If the ratio of Si / In is within this range, the particle size can be made fine, the oxidation resistance can be improved, the particle shape and the particle size variation can be made small, without the conductivity falling or the manufacturing cost being increased. The balance of oxygen can be kept low.

When the copper powder for electrically conductive pastes concerning this invention contains P, Si / P (atm ratio) becomes like this. Preferably it is 4-200, More preferably, it is 10-100. If the ratio of Si / P is within this range, the particle size can be made fine, the oxidation resistance can be improved, the conductivity can be increased, the variation in the shape and particle size of the particles can be reduced, and the concentration of oxygen contained It is easy to balance features that can be lowered.

Similarly, when the copper powder for electrically conductive pastes concerning this invention contains P, In / P (atm ratio) becomes like this. Preferably it is 4-200, More preferably, it is 10-100. If the ratio of In / P is in this range, the particle size can be made fine, the oxidation resistance can be improved, the conductivity can be increased, the variation in the shape and particle size of the particles can be reduced, and the concentration of oxygen contained It is easy to balance features that can be lowered.

Even when the copper powder for electrically conductive pastes which concerns on this invention was manufactured by the wet reduction method, the above-mentioned advantageous effect can be expected to some extent. However, considering that the shape of the particles is uniform and there is an advantage such as little gas generation when used as the conductive paste, the copper powder for the conductive paste according to the present invention is manufactured by the atomizing method. desirable.

The atomization method includes a gas atomization method and a water atomization method. If the particle shape is to be balanced, the gas atomization method may be selected. The water atomization method may be selected if the particles are to be miniaturized. Moreover, it is preferable that the copper powder for electrically conductive pastes concerning this invention was manufactured by the high pressure atomization method among the atomization methods. The copper powder obtained by the high pressure atomization method is preferable because the particles become more uniform or finer. The high pressure atomizing method is a method of atomizing at a water pressure of about 50 MPa to 150 MPa in the water atomizing method, and a method of atomizing at a gas pressure of about 1.5 MPa to 3 MPa in the gas atomizing method.

The copper powder for the conductive paste according to the present invention is also at least one of Ni, Al, Ti, Fe, Co, Cr, Mg, Mn, Mo, W, Ta, Zr, Nb, B, Ge, Sn, Zn, Bi, and the like. It may contain more than a kind of elemental component. By containing these elemental components, various characteristics required for the conductive paste can be improved. As such a characteristic, the melting | fusing point of a copper powder is reduced, for example, and sinterability is improved. The addition amount of these elements with respect to copper is suitably set based on the electrically-conductive characteristic, other various characteristics, etc. according to the kind of element to add. The addition amount is about 0.001 mass%-about 2 mass% normally.

The copper powder for electroconductive paste which concerns on this invention does not have a restriction | limiting in particular in the shape of particle | grain, It can select according to a use. For example, shapes such as particle shape, plate shape, flake shape, dendrite shape, needle shape, and rod shape can be adopted. Usually, it is preferable that the copper powder for electrically conductive pastes shows particle shape in order to aim at the improvement of the dispersibility in a paste component. In particular, it is more preferable to exhibit a spherical shape. The particle shape means a shape having an aspect ratio (value obtained by dividing the average long diameter by the average short diameter) at about 1 to 1.25. A shape having an aspect ratio of about 1 to 1.1 is particularly called a spherical shape. The state in which the shape is not provided is called indefinite shape. The copper powder which forms a particle shape has few entanglement with each other. Therefore, when the copper powder which forms a particle | grain form is used for the electrically-conductive material of an electrically conductive paste, etc., since the dispersibility in a paste improves, it is very preferable.

The copper powder for conductive paste according to the present invention has little variation in the particle size distribution when the coefficient of variation (SD / D ₅₀ ) obtained from the volume cumulative particle diameter (D ₅₀ ) and the standard deviation value (SD) is 0.2 to 0.6, and the conductive paste is low. It is very preferable because the dispersibility in the paste when used for a conductive material or the like can be improved. SD and D ₅₀ can be measured by a laser diffraction scattering particle size distribution analyzer etc., for example.

In addition to the value of the coefficient of variation SD / D _{50 in} the above-described range, the SD and the value of D ₅₀ itself are preferably in the range of 10 to 20 µm, in particular 13 to 18 µm, and D _{50 in the range} of 20 to 30 µm. Do.

The copper powder for electrically conductive pastes concerning this invention is suitable for the electrically-conductive material of the electrically conductive paste for fine conductor circuit formation, by making the average particle number average particle diameter into 0.01 micrometer-50 micrometers. The primary particle number average particle diameter can be measured, for example, by the method of image analysis of a scanning electron microscope observation photograph.

The copper powder for electrically conductive pastes concerning this invention can ensure reliably, and can be suitable for the electrically-conductive material of an electrically conductive paste by making initial (after manufacture) containing oxygen concentration into 30 ppm-2500 ppm. Containing oxygen concentration is measured by the method as described in the Example mentioned later.

The copper powder for conductive pastes according to the present invention is the difference between [weight change rate (TG (%)) / specific surface area (SSA)] at 250 ° C and 800 ° C by thermogravimetric and differential thermal analysis device (hereinafter, Δ (TG / SSA)) is preferably 1% / m 2 / cm 3 to 60% / m 2 / cm 3, more preferably 1% / m 2 / cm 3 to 25% / m 2 / cm 3. The weight change rate (TG (%)) is a value based on the weight of the copper powder at 30 degreeC. Δ (TG / SSA) is defined as (TG / SSA) ₈₀₀ − (TG / SSA) ₂₅₀ . Weight change rate (TG) and specific surface area (SSA) are measured by the method as described in the below-mentioned Example.

According to this characteristic value of (DELTA) (TG / SSA), the oxidation resistance of a copper powder can be evaluated. The temperature range of 250 ° C. to 800 ° C. is a heating temperature range when a main conductive paste including a conductive paste for firing external electrodes of a ceramic capacitor is used, for example. Therefore, it is very important that the copper powder has oxidation resistance in this region. Oxidation resistance of a copper powder is fully exhibited as this (DELTA) (TG / SSA) is said preferable range, and high electrical conductivity can also be ensured. In this invention, the value of (DELTA) (TG / SSA) of a copper powder can be made into the said preferable range by setting the quantity of Si and In contained in particle | grains in the above-mentioned range. In particular, by containing P in the above-mentioned amount in the particles, the value of Δ (TG / SSA) of the copper powder can be made easier within the above-mentioned preferred range.

Next, the preferable specific manufacturing method of the copper powder for electrically conductive pastes which concerns on this invention is demonstrated.

The copper powder for electrically conductive paste of this invention adds Si component to molten copper in the form of a mother alloy, a compound, etc., or In component in the form of an ingot, a shot metal, etc. It can manufacture by powdering by the method.

According to the above production method, it is possible to produce a copper powder in which the balance of oxidation resistance and conductivity is not impaired even though the particle size is fine. Moreover, the copper powder with little dispersion | variation in the shape and particle size of particle | grains, and the density | concentration of oxygen contained can be manufactured.

Although this reason is not certain, it is guessed that Si and In added to molten copper or a copper alloy hold | maintain oxygen in a copper particle and suppress oxidation in the range which does not impair the electroconductivity of a copper particle.

In the production of the copper paste for the conductive paste of the present invention, by adding the Ag component in addition to the Si and In components, the oxidation resistance of the copper powder can be secured and the conductivity can be improved.

If the P component is added to the Si and In components, the surface tension of the molten metal at the time of atomization can be reduced, and it is speculated that the particle-shaped uniformity and the deoxygenation in the molten metal are effectively performed. The addition of the P component may be performed by adding a predetermined amount of the P component to the molten copper in the form of a master alloy or a compound, similarly to the Si component.

In the above production method, it is preferable to employ the high pressure atomizing method for the reasons described above. However, when the water atomizing method is adopted as compared to the gas atomizing method, the yield of the content of Si, In and P may be lower. Therefore, the amount of Si and In is determined with respect to the net amount in the target copper powder. In the case of 1 to 10-fold amount is added, in the case of P, it is necessary to add 1 to 100-fold amount.

In the atomizing method, the target copper powder can be produced smoothly by appropriately controlling the temperature of the molten metal, the diameter of the nozzle for spraying the molten metal, the pressure of spraying, the temperature of the gas or water, and the like.

In the above production method, the copper powder obtained by the atomizing method may be reduced. By this reduction treatment, the oxygen concentration on the surface of the copper powder which is easily prone to oxidation can be further reduced. The reduction treatment is preferably performed by gas from the viewpoint of workability. There is no restriction | limiting in particular in the gas for a reduction process. For example, a gas having reducibility such as hydrogen gas, ammonia gas, butane gas, and the like can be used.

It is preferable to perform said reduction process at the temperature of 150 degreeC-300 degreeC, and it is more preferable to carry out especially at the temperature of 170 degreeC-210 degreeC. This reason is because, when the temperature of the reduction treatment is in the above range, the reduction of the reduction treatment due to the reduction of the reduction rate can be prevented, and the aggregation and sintering of the copper powder can be suppressed. If the temperature of the reduction treatment is 170 ° C to 210 ° C, the aggregation and sintering of the copper powder can be reliably suppressed while reducing the oxygen concentration, which is more preferable.

In the above production method, it is preferable to classify the copper powder obtained by the atomizing method. Classification can be performed easily by isolate | separating granules and microparticles | fine-particles from a copper powder using a suitable classification apparatus so that the target particle size may become a center. In particular, it is preferable to classify so that the coefficient of variation (SD / D ₅₀ ) described above may be 0.2-0.6.

Thus, the electrically conductive paste containing the copper powder for electrically conductive pastes of this invention is manufactured by mix | blending various additives, such as resin, such as an epoxy resin, and its hardening | curing agent, and carrying out operation, such as kneading | mixing to the obtained copper powder. The composition of such a conductive paste is well known in the art, and there is no particular description in detail. In this electrically conductive paste, although the copper powder contained in it is fine particle size, oxidation resistance and electroconductivity are balanced, there are few particle shapes, and the density | concentration of oxygen contained is low. Therefore, this electrically conductive paste is used suitably for formation of various electrical contact members, such as formation of the conductor circuit by the screen printing additive method, formation of the external electrode of a multilayer ceramic capacitor. In addition, the copper paste for the conductive paste of the present invention is an internal electrode of a multilayer ceramic capacitor, a chip component such as an inductor or a resistor, a single plate capacitor electrode, a tantalum capacitor electrode, a resin multilayer substrate, a ceramic (LTCC) multilayer substrate, a flexible printed circuit board ( FPC), antenna switch module, module such as PA module or high frequency active filter, electronic shielding film for PDP front panel and back panel or PDP color filter, crystalline solar cell surface electrode and back extraction electrode, conductive adhesive, EMI shield, RF- It can also be used for membrane switches such as ID and PC keyboards, and anisotropic conductive films (ACF / ACP).

Hereinafter, the present invention will be described in more detail based on the following Examples and Comparative Examples.

(Example 1)

After filling the inside of the chamber and the raw material dissolution chamber of a gas atomizing device (Nisshingiken Co., Ltd. type, NEVA-GP2 type | mold) with nitrogen gas, the raw material was heat-dissolved in the carbon crucible installed in the dissolution chamber, and it was set as the melt. Specifically, 1.77 g of metallic silicon (NIKSIL manufactured by Nihon Kinzoku Chemical Co., Ltd.) and 7.20 g of metal indium were added to the molten metal in which the electro-copper was melted to form an 800 g of molten metal, and the mixture was sufficiently stirred and mixed. Thereafter, the molten metal was sprayed at 1250 ° C. and 3.0 MPa with a nozzle having a diameter of 1.5 mm to obtain a copper powder containing silicon and indium inside the particles. Thereafter, the obtained copper powder was sieved with a 53 μm test sieve, and the sieve product was used as the final copper powder. The characteristics of the obtained copper powder are shown in Table 2. In this copper powder, Si and In were unexposed to the particle surface, and were unevenly distributed in the vicinity of the particle surface.

(Examples 2 to 14)

In addition to the metal silicon and the metal indium, a copper powder was obtained in the same manner as in Example 1 except that silver silver and a copper-phosphorus master alloy (phosphorus grade 15 mass%) were added as shown in Table 1.

(Comparative Examples 1 to 8)

Copper powder was obtained by operation similar to Example 1 except having added the addition amount of the metal silicon, the metal indium, and the copper- phosphorus master alloy (15 mass% of phosphorus grades) as shown in Table 1.

Various characteristics were evaluated by the method shown below about the copper powder obtained by the Example and the comparative example. The results are shown in Tables 2-6.

(1) silicon, indium, phosphorus content

The sample was dissolved with acid and the solution analyzed by ICP. The results are shown in Table 2.

(2) oxygen concentration

The analysis was carried out with an oxygen / nitrogen analyzer (EMGA-520 (model number) manufactured by Horiba Seisakusho Co., Ltd.). The results are shown in Table 2. In addition, in order to evaluate the deterioration of the oxidation resistance over time, the temperature of the air flow was raised to 200 ° C. at 8 L / min and a heating rate of 10 ° C./min using a Sanyo Seiko SK-8000, and then maintained at the same temperature for 1 hour. The oxygen concentration of the sample was also measured. The results are shown in Table 5.

(3) Δ (TG / SSA)

Tg (%) at 40 ° C to 800 ° C by differential thermal thermogravimetry (TG / DTA) (SII, TG / DTA6300 high temperature type) (raising temperature: 10 ° C / min, air flow rate: 200mL / min) Was measured. On the other hand, the specific surface area was calculated | required from the particle size distribution measured with the particle size measuring device (The Nikkiso product, Microtrack MT-3000 type). TG / SSA was arithmetically calculated from both measurements. The results are shown in Table 3. Table 3 also describes the Δ (TG / SSA) value, which is the difference between TG / SSA at 250 ° C. and TG / SSA at 800 ° C. In addition, the value obtained by dividing TG / SSA at each temperature by TG / SSA (described as [TG / SSA] _{Cu in} Table 4) of the pure copper powder of Comparative Example 8 was also obtained. The results are shown in Table 4.

(4) particle shape

Observation was performed with a scanning electron microscope. The results are shown in Table 2.

(5) D ₅₀ , SD, SD / D ₅₀

0.2 g of the sample was poured into 100 ml of pure water, irradiated with ultrasonic waves for 3 minutes and dispersed, and then deposited in a volume distribution analyzer (Microtrack (trade name) FRA (Model No.) manufactured by Nikkiso KK). Particle diameter (D ₅₀ ), standard deviation (SD) and coefficient of variation (SD / D ₅₀ ) were obtained, respectively. The results are shown in Table 2.

(6) volume resistivity

15 g of the sample was placed in a cylindrical container, and a measurement sample formed by compression molding at a press pressure of 40 × 10 ⁶ Pa (408 kgf / cm 2) was formed. For this measurement sample, the LORESTA AP and LORESTA PD-41 ( All were measured using Mitsubishi Kagaku Co., Ltd. product. The results are shown in Table 6.

As is apparent from Tables 3 and 4, the copper powders of the examples are excellent in oxidation resistance in the temperature range of 250 to 800 占 폚. Particularly in the temperature range of 600 to 800 ° C., the copper powder of the example (copper powder containing both Si and In inside the particles) was added to the copper powder of the comparative example (copper powder containing only either Si or In inside the particles). Compared with the oxidation resistance is remarkably excellent.

Moreover, as shown in Table 5, when the copper powder of an Example is kept for a long time in the environment which is easy to oxidize, compared with the copper powder of a comparative example, the time-dependent deterioration of oxidation resistance is suppressed remarkably. In particular, although the copper powders of Comparative Examples 1, 2, 4, and 5 had a relatively high total content of Si and In of about 2 atm%, the copper powder of the Example had a relatively low total content of Si and In of about 1 atm%. And it can be seen that deterioration with oxidation resistance is suppressed over time.

Moreover, as shown in Table 6, it was confirmed that the volume resistivity of the copper powder of the Example containing Ag component is inferior compared with the copper powder to which nothing was added.

Claims (8)

A copper powder for conductive paste, characterized by containing 0.1 atm% to 10 atm% of Si (silicon) and 0.1 atm to 10 atm% of In (indium) in the particles. The method of claim 1,
A copper powder for conductive paste, which contains 0.1 atm% to 10 atm% of Ag (silver) in the particles. The method according to claim 1 or 2,
Si / In (atm ratio) is 0.5-5, The copper powder for electrically conductive pastes characterized by the above-mentioned. 4. The method according to any one of claims 1 to 3,
Copper powder for electrically conductive pastes containing 0.01atm%-0.5atm% of P (phosphorus) in particle inside. The method of claim 4, wherein
Si / P (atm ratio) is 4-200, The copper powder for electrically conductive pastes characterized by the above-mentioned. The method according to claim 4 or 5,
In / P (atm ratio) The copper powder for electrically conductive pastes characterized by 4-200. The method according to any one of claims 1 to 6,
A copper powder for conductive paste, which is produced by the atomizing method. The electroconductive paste containing the copper powder for electroconductive pastes in any one of Claims 1-7.