JP2018125148A - Powder for conductive filler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide powder for conductive filler that has excellent electric conductivity, excellent long term stability of the electric conductivity, and low density, and can be obtained at a low cost.SOLUTION: A material of powder for conductive filler is an alloy containing Si, a conductive element X1 and inevitable impurities. The element X1 is any one kind selected from Ti, Co and Ni, the alloy has a silicide phase mainly made of silicide constituted from Si and the element X1, and the silicide is the conductive filler powder that is any one kind selected from TiSi, CoSiand NiSi. A volume fraction Psc of the silicide in the alloy is 95% or higher, the density of the powder is 3.5 to 7.0 Mg/m, an oxygen content of the alloy is 0.5 mass% or smaller, and a thickness T1 of a surface oxide film of the powder is 1.0 nm or thinner.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a powder suitable for a conductive filler used in a conductive resin, a conductive plastic, a conductive paste, an electronic device, an electronic component, and the like. Specifically, the present invention relates to a powder whose material is an alloy containing Si.

  Noble metal particles such as Au, Ag, Pt and Cu are used for the filler contained in the conductive material. Particles in which noble metals are coated on the surface of other metals are also used as conductive fillers. Since the electrical resistance of the noble metal is small, the filler containing the noble metal is excellent in conductivity. Since a large contact area between the particles can be obtained by aggregation of the particles containing the noble metal, the noble metal contributes to the conductivity of the filler also from this viewpoint. Precious metals are also excellent in thermal conductivity.

  Precious metals are expensive. Therefore, a conductive material containing a noble metal is expensive. Moreover, noble metals have a high specific gravity. Therefore, the conductive substance containing a noble metal is heavy. From the viewpoint of cost reduction and weight reduction, various studies have been made on alloys containing elements other than noble metals.

  Japanese Unexamined Patent Application Publication No. 2004-47404 discloses an alloy for conductive filler in which the surface of particles made of a Si-based compound is coated with carbon. In these particles, Si microcrystals are dispersed in the Si-based compound.

  Japanese Patent Application Laid-Open No. 2006-54061 discloses an alloy for conductive filler in which the surface of particles made of Ag is coated with Si or a Si-based compound.

Japanese Unexamined Patent Application Publication No. 2008-262916 discloses an alloy for conductive fillers containing Ag and 0.01 to 10% by mass of Si. In this alloy, the surface of Ag particles is coated with SiO ₂ gel.

  Japanese Unexamined Patent Application Publication No. 2006-302525 discloses a conductive filler powder made of an Ag alloy containing Al or Si.

  International Publication WO99 / 22411 discloses a conductive alloy containing Si and an additive element of 0.001 at% or more and 20 at% or less.

  Japanese Patent No. 4337501 discloses a conductive paste based on Ni and containing Mg, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Al, or Si. This publication further discloses a conductive paste based on Cu and containing Mg, Ca, Ti, Zr, V, Nb, Mn, Fe, Co, Al or Si.

  Japanese Patent No. 4678654 discloses a conductive material having high melting point metal particles containing Ag, Cu, Au, Pt, Ti, Zn, Al, Fe, Si or Ni and low melting point metal particles containing Sn, In or Bi. A layer is disclosed.

Japanese Unexamined Patent Application Publication No. 2016-110773 discloses a conductive filler powder containing Si. The specific gravity of this powder is as small as 2-6Mg / m ³ and is easily kneaded with the resin.

JP 2004-47404 A JP 2006-54061 A JP 2008-262916 A JP 2006-302525 A International Publication No. WO99 / 22411 Japanese Patent No. 4337501 Japanese Patent No. 4678654 JP 2016-110773 A

  As described above, particles made of a noble metal are used as the conductive filler. Typical particles are Ag particles, Ag coated particles and Cu particles. Ag particles are extremely excellent in electrical conductivity, but the Ag particles are easily deteriorated by ion migration. This Ag particle is inferior in the long-term stability of electrical conductivity.

  Ag coated particles are superior to Ag particles in terms of cost. However, with this Ag coated particles, the coating layer is easily peeled off. Furthermore, when the substrate is Cu, the electrical conductivity is inferior in long-term stability, and when the substrate is Si, glass or the like, the conductivity is insufficient.

  In the case of Cu particles, corrosion tends to occur. These Cu particles are also inferior in the long-term stability of electrical conductivity. A powder excellent in the long-term stability of electrical conductivity is desired.

  In many cases, the conductive filler powder is blended with the resin powder, and a molded body is formed from a mixture obtained by the blending. In this molding, the mixture is generally heated. The resin is melted by heating. If the density of the conductive filler powder is excessive, the conductive filler powder settles in the mixture when the resin is melted. Due to the sedimentation, uneven distribution of the conductive filler powder occurs. In this molded body, the electric conduction network is locally broken. A conductive filler powder having a low density is desired.

  Atomization is known as an efficient method for producing a conductive filler powder. Particles obtained by atomization are usually larger than particles obtained by electrolytic methods, chemical reduction methods and the like. Therefore, depending on the application, it is necessary to classify the particles. However, classification reduces the yield of the material. In order to achieve a high yield, it is necessary to pulverize and refine the particles obtained by atomization. When particles made of a material having a high spreadability are pulverized, flattening occurs and it is difficult to make them fine. An alloy for filler that is easy to grind is desired.

  As described above, noble metals such as Au, Ag, Pt and Cu are expensive. Furthermore, Al, Cr, Mg, Na, Mo, Rh, W, Be, Ir, Zn, K, Cd, Ru, In, Li, Os, Co, Pt, P, Pd, which are conductive elements other than noble metals, Sn, Ni, Ta, Rb, Tl, Th, Pb, Sr, V, Sb, Zr, Ca, etc. are also relatively expensive. These elements increase the cost of the conductive filler powder. Fe is obtained at a relatively low cost, but is easily oxidized. Anti-rust measures are necessary for particles made of Fe. This rust prevention measure increases the cost of the powder. Furthermore, pure metal elements of Al, Mg, Na, Be, K, Li, P, Rb, Tl, Th, Pb, Sr, Zr and Ca are active, and there is a risk of dust explosion in the fine powder state. . Explosion prevention measures are necessary for powders composed of these elements. This measure increases the cost of the powder. Powders obtained at low cost are desired.

  The powder disclosed in JP-A-2004-47404 contains a large amount of Si microcrystals. The conductivity of this powder is insufficient.

  The powder disclosed in Japanese Patent Application Laid-Open No. 2006-54061 is expensive because it contains a large amount of Ag. Similarly, the powder disclosed in Japanese Patent Application Laid-Open No. 2008-262916 and the powder disclosed in Japanese Patent Application Laid-Open No. 2006-302525 are also expensive.

  The alloy disclosed in International Publication No. WO99 / 22411 contains a large amount of Si. In the powder obtained by atomization from this alloy, the Si phase hinders conductivity.

  The powder suitable for the paste disclosed in Japanese Patent No. 4337501 is difficult to obtain by atomization. The production cost of this powder is high.

  Although the specific gravity of the conductive filler powder disclosed in Japanese Patent Application Laid-Open No. 2016-110773 is light, it contains a large amount of insulating Si, so that the conductivity is not sufficient.

  An object of the present invention is to provide a powder for a conductive filler that is excellent in conductivity, excellent in long-term stability of electric conductivity, low in density, and obtainable at low cost.

The conductive filler powder according to the present invention comprises a large number of particles. The material of each particle is an alloy containing Si, the conductive element X1, and inevitable impurities. The element X1 is any one selected from the group consisting of Ti, Co, and Ni. This alloy has a silicide phase mainly composed of silicide composed of Si and the element X1. This silicide is any one selected from the group consisting of TiSi ₂ , CoSi ₂ and NiSi. The volume ratio of the silicide in the silicide phase is 95% or more. The density of this powder is 3.5 Mg / m ³ or more and 7.0 Mg / m ³ or less. The oxygen content of this alloy is 0.5 mass% or less. The thickness T1 of the surface oxide film of these particles is 1.0 nm or less. After this powder is allowed to stand for 5 hours in an environment where the temperature is 85 ° C. and the humidity is 85% RH, the thickness T2 of the surface oxide film of the particles is 2.0 nm or less.

According to another aspect, the material of each particle is an alloy containing Si, the conductive element X1, Ag, and inevitable impurities. The element X1 is any one selected from the group consisting of Ti, Co, and Ni. This alloy has an Ag phase and a silicide phase mainly composed of silicide composed of Si and the element X1. This silicide is any one selected from the group consisting of TiSi ₂ , CoSi ₂ and NiSi. The volume ratio of the silicide in the silicide phase is 95% or more. The density of this powder is 3.5 Mg / m ³ or more and 7.0 Mg / m ³ or less. The oxygen content of this alloy is 0.5 mass% or less. The thickness T1 of the surface oxide film of these particles is 1.0 nm or less. After this powder is allowed to stand for 5 hours in an environment where the temperature is 85 ° C. and the humidity is 85% RH, the thickness T2 of the surface oxide film of the particles is 2.0 nm or less.

  Since the conductive filler powder according to the present invention is an alloy containing Si, it can be obtained at low cost. This powder is also low density. In this powder, silicide contributes to conductivity. With this powder, excellent electrical conductivity can be exhibited over a long period of time.

FIG. 1 is a graph showing the correlation between the thickness of the surface oxide film of the powder and the decreasing rate of electric conductivity.

The conductive filler powder according to the present invention is an aggregate of a large number of particles. The material of the particles is an alloy. This alloy contains Si and the element X1. The element X1 is conductive. The electric conductivity of the element X1 is 1 × 10 ⁷ AV ⁻¹ m ⁻¹ or more. Preferably, the alloy contains Si and the element X1, with the balance being inevitable impurities.

  In this alloy, Si and the element X1 form silicide. As will be described later, this silicide contributes to the conductivity of the powder. This alloy has a silicide phase mainly composed of this silicide.

  Si is less expensive than noble metals. The conductive filler powder containing Si achieves the low cost of the object containing this powder. Furthermore, this powder can be produced without the hassle of coating.

As described above, noble metals such as Au, Ag, Pt and Cu are used for the conventional conductive filler powder. The density of Au is 19.32 Mg / m ³ , the density of Ag is 10.50 Mg / m ³ , the density of Pt is 21.45 Mg / m ³ , and the density of Cu is 8.960 Mg / m ³ . is there. On the other hand, the density of Si is 2.329 Mg / m ³ . The density of Si is small among metals. The conductive filler powder containing Si is lightweight. An object (for example, an electronic device) containing this powder is lightweight.

  The element X1 is any one selected from the group consisting of Ti, Co, and Ni. The element X1 can contribute to the conductivity of the powder. From the viewpoint of conductivity, the alloy does not contain two or more elements X1 except for the inclusion as an inevitable impurity. In this silicide phase, deterioration due to oxidation or the like is unlikely to occur. This powder has excellent long-term stability of electrical conductivity.

  Si is a metal with low electrical conductivity. On the other hand, the electrical conductivity of the silicide containing the element X1 is high. The reason is presumed that the concentration of carriers responsible for electrical conduction in this silicide is extremely higher than that in Si. This powder containing silicide is excellent in conductivity. An object (for example, an electronic device) containing this powder is excellent in conductivity.

Silicide is any one selected from the group consisting of TiSi ₂ , CoSi ₂ and NiSi. The electric conductivity of this silicide is particularly high. A silicide phase that substantially does not contain two or more types of silicides selected from the group consisting of TiSi ₂ , CoSi _2, and NiSi is preferable. Here, “substantially free” means that the presence of silicide derived from an element which is an inevitable impurity is allowed. In an alloy in which the silicide phase substantially does not contain two or more types of silicide, electron scattering is suppressed.

  It is preferable that the silicide phase does not substantially contain other silicide composed of Si and two or more elements X1. Here, “substantially free” means that the presence of another silicide derived from an element that is an inevitable impurity is allowed. In an alloy whose silicide phase is substantially free of silicide composed of Si and two or more elements X1, scattering of electrons is suppressed.

The silicide phase may contain some other silicides other than TiSi ₂ , CoSi ₂ and NiSi. The alloy can include a Si phase and an impurity phase in addition to the silicide phase. From the viewpoint of conductivity, the volume ratio Psc of silicide (TiSi ₂ , CoSi ₂ or NiSi) in the alloy is preferably 95% or more, more preferably 97% or more, and particularly preferably 99% or more. The volume ratio Psc is ideally 100%. In the resin in which the powder is embedded, the volume ratio is calculated by observing the cross section of the particle with a microscope. The results obtained by observing 100 particles are averaged to calculate the volume ratio Psc.

  The toughness of this silicide phase is low. Therefore, the powder containing the silicide phase can be easily pulverized. In other words, the particle size distribution of the powder can be easily adjusted. Since the particle size distribution is easily adjusted, atomization can be employed in the production of this powder. The production cost of this powder is low. The pulverization is performed as necessary. Grinding is not an essential process.

  The alloy may contain Ag. In this case, the alloy preferably contains only Si, the conductive element X1, Ag and unavoidable impurities. In this case, the alloy has an Ag phase together with a silicide phase. The electrical resistance of the Ag phase is small. This Ag phase increases the conductivity of the powder.

  When the alloy contains an Ag phase, the volume ratio Psc of silicide in the portion other than the Ag phase of the alloy is preferably 95% or more, more preferably 97% or more, and particularly preferably 99% or more. The volume ratio Psc is ideally 100%.

  When Ag and another metal form an intermetallic compound, the conductivity is not sufficiently improved. From this viewpoint, the ratio of the Ag single phase to the Ag content is preferably 95 at% or more.

  Preferably, the alloy containing Ag contains either Ti or Ni as the element X1. In other words, it is preferable that the alloy containing Ag does not substantially contain Co. This is because an alloy containing Si, Co, and Ag is difficult to form a highly pure silicide phase and Ag phase.

  From the viewpoint of light weight and low cost, the Si content in the alloy is preferably 40% by mass or more. From the viewpoint that the alloy can contain sufficient element X1, the Si content is preferably less than 70% by mass.

  From the viewpoint of conductivity, the content of the element X1 in the alloy is preferably 20% by mass or more, more preferably 30% by mass or more, and particularly preferably 40% by mass or more. From the viewpoint that the alloy can contain sufficient Si, the content of the element X1 is preferably less than 60% by mass.

  When this alloy contains Ag, the content of Ag is preferably 1 at% or more, and particularly preferably 2 at% or more from the viewpoint of conductivity. From the viewpoint of low cost and light weight, the Ag content is preferably 10 at% or less.

From the viewpoint of weight aspects and powder ubiquitous suppression, the density of the powder is preferably 7.0 mg / ^{m 3} or less, more preferably 6.5 mg / ^{m 3} or less, 6.0 mg / ^{m 3} or less is particularly preferred. From the viewpoint of electrical conductivity, density is preferably 3.5 mg / ^{m 3} or more, 4.5 mg / ^{m 3} or more is more preferable.

  The density is measured by a dry automatic densimeter “Acupic II 340 series” manufactured by Shimadzu Corporation. The container of this apparatus is charged with powder and filled with helium gas. Based on the constant volume expansion method, the density of the powder is detected. An average value of 10 measurements is calculated.

The electrical conductivity of the powder is preferably 9000 × 10 ² AV ⁻¹ m ⁻¹ or more, more preferably 9500 × 10 ² AV ⁻¹ m ⁻¹ or more, particularly preferably 10000 × 10 ² AV ⁻¹ m ⁻¹ or more. . In the measurement of electrical conductivity, particles with a diameter exceeding 45 μm are removed from the powder by a sieve. The electrical conductivity of the powder is measured by a powder resistivity measuring unit “MCP-PD51” and a low resistance measuring device “Lorestar GX” manufactured by Mitsubishi Chemical Analytech. The electrical conductivity is the specific resistance of the filler in which the powder is pressed.

  It is preferable that the surface oxide film thickness of the powder is small. The reason is as follows.

  Generally, the conductive filler is kneaded together with an organic resin that is insulating and an organic solvent to form a conductive paste. By removing the organic solvent from the conductive paste, the paste is solidified. Except for special cases where particles can be completely sintered, such as nanoparticles that exhibit a melting point lowering phenomenon, composites in which conductive particles are dispersed in an insulating organic material Are not in full contact. In this composite, there is a report that conduction occurs through an insulating barrier (see “Measurement, Evaluation and Data Interpretation of Electrical Characteristics”, September 2015, Technical Information Association, Inc., page 8). In the case of metal fillers, it has been reported that the electron transfer mechanism between fillers is tunnel conduction or weakly localized conduction that is intermediate between hopping conduction and band conduction. Although the mechanism of electrical conduction is not clear, it is considered that the thickness of the insulator between the particles greatly affects the electrical conductivity because the particles are not in physical contact.

  Not only the organic substance between particles but also the oxide film on the particle surface can be regarded as being included in the concept of “insulator between particles”. In order to exhibit the tunnel effect, it is considered that the thickness of the insulator needs to be 10 nm or less. Since the oxide films of both the adjacent first particles and second particles are included in the insulator, the thickness of the oxide film of one particle is 5 nm or less even if the thickness of the organic substance is assumed to be 1 nm or less. There is a need. The thinner the thickness, the higher the electrical conductivity of the powder.

  The inventor has compared the thicknesses of the surface oxide films of various powders with the electric conductivity of the powder-filled state and the electric conductivity of the paste solidified product. As a result, it was found that the thickness T1 of the surface oxide film needs to be 1.0 nm or less in order for the powder to exhibit low electrical conductivity. Preferably, this thickness T1 is 0.5 nm or less. Ideally, this thickness T1 is 0.0 nm. The thickness T1 is measured after the powder is manufactured (ie, atomized, milled, etc.) and stored indoors, that is, not exposed to a high-temperature and high-humidity environment.

  In the graph of FIG. 1, the horizontal axis represents the thickness T2 (nm) of the surface oxide film of the powder after the powder was allowed to stand for 5 hours in an environment where the temperature is 85 ° C. and the humidity is 85% RH. It is. In this graph, the vertical axis represents the decrease rate Pd (%) of electrical conductivity that occurs when the powder is left for 1000 hours in an environment where the temperature is 85 ° C. and the humidity is 85% RH. As is apparent from this graph, there is a correlation between the thickness T2 and the decrease rate Pd.

  In the powder according to the present invention, the thickness T2 is 2.0 nm or less. When the powder is in practical use, the matrix resin absorbs moisture from the atmosphere. This moisture promotes the formation or growth of the surface oxide film. In the powder according to the present invention, since the thickness T2 is 2.0 nm or less, even if moisture enters the matrix resin, the electric conductivity is hardly lowered. Generally, the conductive filler powder has a reduction rate of electric conductivity of 50% or less when left for 1000 hours in an environment where the temperature is 85 ° C. and the humidity is 85% RH. Requested. The present inventor has found that this requirement is satisfied by a powder having a thickness T2 of 2.0 nm or less. The thickness T2 is more preferably 1.5 nm or less, and particularly preferably 1.0 nm or less. Ideally, this thickness T2 is 0.0 nm.

  The thickness (T1 or T2) is measured by an Auger measuring device (for example, an electrolytic emission Auger electron spectroscopic analyzer MODEL680 manufactured by ULVAC-PHI). In the measurement, first, a block is cut out from an ingot having the same composition as that of the powder obtained by a casting method. Next, the surface of this block is oxidized, and the thickness of the oxide film is measured by TEM. This ingot is subjected to Auger spectroscopic analysis to calculate the sputtering rate of the surface oxide film. Next, the particles of the powder are subjected to Auger spectroscopic analysis to calculate the thickness (T1 or T2). The thickness (T1 or T2) is defined as the sputtering depth until the detected intensity of oxygen becomes 1/2 of the maximum intensity.

  The oxygen content of this alloy is preferably 0.5 mass% or less. In an alloy having an oxygen content of 0.5 mass% or less, the growth of the surface oxide film is suppressed. In this respect, the oxygen content is more preferably equal to or less than 0.4 mass%, and particularly preferably equal to or less than 0.3 mass%. The smaller the oxygen content, the better.

  If necessary, an Ag coating layer may be formed on the surface of the powder particles according to the present invention. This coating layer contributes to electrical conductivity. Since the powder according to the present invention has excellent oxidation resistance and high electrical conductivity, even if the coating phase is peeled off, the performance is not significantly reduced. The coating layer can be formed by a known method.

  The conductive filler powder according to the present invention can be produced by a liquid quenching process including an atomizing step. By this process, the powder can be produced easily and inexpensively. Examples of preferable atomization include a gas atomization method, a disk atomization method, and a plasma atomization method. From the viewpoint of suppressing the oxygen content, the gas atomizing method and the disk atomizing method are particularly preferable.

  Hereinafter, the details of preferable atomization will be described. In the following description, the conditions for atomization are only examples. The conditions can be changed as appropriate according to circumstances such as use.

  In the gas atomization method, raw materials are put into a quartz crucible having pores at the bottom. This raw material is heated and melted by a high frequency induction furnace in an argon gas atmosphere. In an argon gas atmosphere, argon gas is injected onto the raw material flowing out from the pores. The raw material is rapidly cooled and solidified to obtain a powder. The coagulation rate can be controlled by adjusting the injection pressure. The greater the injection pressure, the greater the solidification rate. By controlling the solidification rate, a powder having a desired particle size distribution can be obtained. The faster the solidification rate, the smaller the width of the particle size distribution.

  In the disk atomization method, raw materials are put into a quartz crucible having pores at the bottom. This raw material is heated and melted by a high frequency induction furnace in an argon gas atmosphere. In an argon gas atmosphere, the raw material flowing out from the pores is dropped onto a disk that rotates at high speed. The raw material is rapidly cooled by the disk and solidified to obtain a powder.

  The powder obtained by these atomizations may be used as a conductive filler as it is. The powder obtained by the atomization may be pulverized to obtain a conductive filler. The pulverized particles can exist as fine crystal grains. Mechanical milling is exemplified as a pulverization method.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

  The powders of Example 1-14 and Comparative Example 1-16 having the compositions shown in Table 1-2 were obtained. Each powder contains unavoidable impurities not listed in Table 1-2. In Table 2, portions that do not satisfy the invention-specific matters of the present invention are underlined.

[Electric conductivity]
The electrical conductivity of the powder pressed at a pressure of 64 MPa was measured by the method described above. The results are shown in Table 1-2 below.

[Decrease rate of electrical conductivity]
Powder, an epoxy resin, and a diluent (butyl carbitol) were mixed to obtain a paste. In this paste, the volume ratio of the powder to the epoxy resin was 1: 1. The amount of diluent was adjusted so that the viscosity of the paste was appropriate. A substrate having two terminals with a distance of 1 cm between each other was prepared. The material of each terminal is Ag. Between these terminals, a conductive paste was applied by screen printing to obtain a line. The width of this line was 50 μm. The substrate was heated to 200 ° C. under atmospheric pressure and heated for 30 minutes to obtain a sample. A tester was connected to each terminal of this sample, and the specific resistance R1 between the terminals was measured. This sample was put into a wetness tester and allowed to stand for 1000 hours under conditions where the temperature was 85 ° C. and the humidity was 85% RH. A tester was connected to each terminal of the sample taken out from the wet testing machine, and the specific resistance R2 between the terminals was measured. The decrease rate Pd of electrical conductivity was calculated according to the following formula. The results are shown in Table 1-2 below.
Pd = ((1 / R1) − (1 / R2)) / (1 / R1) · 100

Details of the manufacturing process in Tables 1 and 2 are as follows.
G. A. : Gas atomization method A. : Disc atomization method

The powder of each example described in Table 1 is
(1) including any one type of silicide selected from the group consisting of TiSi ₂ , CoSi _2, and NiSi;
(2) The silicide volume fraction Psc is 95% or more,
(3) The density of the powder is 3.5 Mg / m ³ or more and 7.0 Mg / m ³ or less,
(4) The oxygen content of the alloy is 0.5 mass% or less,
(5) All conditions that the thickness T1 is 1.0 nm or less and (6) the thickness T2 is 2.0 nm or less are satisfied. These powders are excellent in conductivity and long-term stability of electrical conductivity.

  The powder of each comparative example described in Table 2 does not satisfy any of the above conditions (1) to (6). These powders are inferior in the long-term stability of electrical conductivity or electrical conductivity.

  From this evaluation result, the superiority of the present invention is clear.

  The powder according to the present invention can be used for conductive resins, conductive plastics, conductive pastes, electronic devices, electronic components, and the like.

Claims (3)

A conductive filler powder consisting of a large number of particles, the material of each particle being an alloy containing Si, the conductive element X1, and inevitable impurities,
The element X1 is any one selected from the group consisting of Ti, Co and Ni;
The alloy has a silicide phase mainly composed of silicide composed of Si and the element X1,
The silicide is any one selected from the group consisting of TiSi ₂ , CoSi ₂ and NiSi;
A volume ratio of the silicide in the alloy is 95% or more;
The density of the powder is 3.5 Mg / m ³ or more and 7.0 Mg / m ³ or less,
The oxygen content of the alloy is 0.5 mass% or less,
The surface oxide film thickness T1 of the particles is 1.0 nm or less,
The conductive filler in which the thickness T2 of the surface oxide film of the particles is 2.0 nm or less after the powder is left in an environment where the temperature is 85 ° C. and the humidity is 85% RH for 5 hours. Powder. A conductive filler powder consisting of a large number of particles, each of which is made of an alloy containing Si, conductive elements X1, Ag and inevitable impurities,
The element X1 is any one selected from the group consisting of Ti, Co and Ni;
The alloy has an Ag phase and a silicide phase mainly composed of silicide composed of Si and the element X1,
The silicide is any one selected from the group consisting of TiSi ₂ , CoSi ₂ and NiSi;
The volume ratio of the silicide in a portion other than the Ag phase of the alloy is 95% or more,
The density of the powder is 3.5 Mg / m ³ or more and 7.0 Mg / m ³ or less,
The oxygen content of the alloy is 0.5 mass% or less,
The surface oxide film thickness T1 of the particles is 1.0 nm or less,
The conductive filler in which the thickness T2 of the surface oxide film of the particles is 2.0 nm or less after the powder is left in an environment where the temperature is 85 ° C. and the humidity is 85% RH for 5 hours. Powder. The element X1 is any one selected from the group consisting of Ti and Ni,
The powder according to claim _2, wherein the silicide is any one selected from the group consisting of TiSi ₂ and NiSi.

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