JP2009197317A - REDUCTION PRECIPITATION TYPE SPHERICAL NiP PARTICLE AND PRODUCTION METHOD THEREOF - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spherical NiP particle having excellent monodispersibility of the particle itself and production method thereof. <P>SOLUTION: Disclosed is a reduction-precipitation type spherical NiP particle having constituent with Ni as the body and P (preferably 1 to 15 mass%). The constituent includes Cu (preferably 0.01 to 18 mass%), or furthermore includes Sn (preferably 0.05 to 10 mass%). Also disclosed is a production method for the reduction-precipitation type spherical NiP particle having constituent with Ni as the body and P by mixing the mixed water solution composed of water solution of nickel salt, pH regulator and pH buffer with phosphorous water solution of reductant and reducing and precipitating the mixture, wherein the water solution of nickel salt is prepared by an alkaline method of selecting materials having Cu (preferable mol ratio of Ni/Cu=4.0 to 10000) or furthermore having Sn (preferable mol ratio of Ni/Sn=2.0 to 2000), and mixing the materials to make the pH value exceeds 7 when reduction-precipitation begins. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to, for example, metal microparticles that are also preferable as materials used for wiring formation on substrates and the like, in addition to metal microparticles used as conductive particles for anisotropic conductive films, and a method for producing the same. It is.

  With the spread of terrestrial digital broadcasting, LCD (Liquid Crystal Display) or PDP (Plasma Display Panel) and other FPDs (Flat Panel Display) are rapidly expanding. Many anisotropic conductive films are used for electrical connection of the driver ICs and fine wiring circuits.

  An anisotropic conductive film is an adhesive in which conductive particles are dispersed in a thermosetting or thermoplastic insulating resin film, and the conductive particles are bonded by thermocompression after being placed between opposing wires. It is a connecting material that takes electrical conduction between wirings and maintains electrical insulation between adjacent wirings in the surface direction. The conductive particles include conductive resin balls obtained by plating the surface of resin balls such as polystyrene and acrylic with a metal material such as Ni and Au, and metals such as Ni, Cu, Al, Au, and Ag. Powders or powders whose surfaces are metal-plated are widely used.

  Conductive resin balls generally used as conductive particles in anisotropic conductive films have the advantage that the contact area with the wiring can be increased because the resin balls are elastically deformed by the pressure and temperature during thermocompression bonding. Have. However, since the resin ball is an insulator, not only good conduction is difficult to obtain, but also metal plating on the surface must be performed by a special treatment, so that there is a disadvantage that it is very expensive.

  On the other hand, metal powder such as Ni powder is used for anisotropic conductive films such as TCP (Tape Carrier Package) and FPC (Flexible Printed Circuit) connection, and TCP and PWB (Printed Wiring Board) connection. Circuit boards such as TCP, FPC, and PWB have a fine wiring circuit made of Cu or Sn plating or the like that is relatively soft and easy to form an oxide film. The anisotropic conductive film using metal powder has the above-mentioned features such as the ability to ensure conduction by breaking through the oxide film on the wiring circuit. However, for example, when metal powder obtained by a gas atomizing method is used as conductive particles for anisotropic conductive film, it is very difficult to obtain particles having a sharp particle size distribution. There is a problem that classification processing from irregularly-sized particles to a particle size that can withstand the specifications of the anisotropic conductive film becomes expensive.

  Then, in view of said subject, this inventor has proposed the electroconductive particle disperse | distributed to it about the anisotropic conductive film used for the fine wiring connection of a circuit board (patent document 1). The conductive particles are suitable for anisotropic conductive films because they have excellent conductive properties while achieving high hardness and uniform shape and particle size distribution.

In addition, a screen printing method using an Ag paste or the like is employed to form fine circuit wiring on an FPC or a glass substrate. In this method, after wiring is printed on the substrate with Ag paste having high electrical conductivity, in order to prevent electromigration of Ag, the carbon paste is laminated and printed in the form of coating Ag wiring, and the circuit wiring is formed by baking. It is a method of forming. According to this method, it is possible to manufacture a large number of substrates at a low cost.
JP 2006-131978 A

  In the above background art, for example, when paying attention to the conductive particles for anisotropic conductive film, the method of Patent Document 1 is an effective technique showing a certain effect on the above problem, but with this type of NiP microparticles, When compared with conductive resin balls, there was variation in particle size, and there was room for improvement.

  Further, when evaluated as a material for forming a wiring on an FPC, a substrate, or the like, when forming a finer wiring, for example, with a wiring interval of 0.2 mm or less, the accuracy of screen printing, that is, the Ag wiring and the lamination thereof Therefore, there is a problem that it is difficult to form a highly accurate wiring circuit due to misalignment when printing carbon paste for preventing electromigration. Therefore, in the wiring forming material, there is a demand for conductive particles that can substitute for the Ag paste in order to eliminate the deterioration in accuracy of circuit wiring caused by the problem of electromigration.

  An object of the present invention is to provide spherical NiP microparticles that are particularly suitable for use in conductive particles of an anisotropic conductive film and that are excellent in monodispersity and conductive properties, and a method for producing the same. In addition to this, spherical NiP microparticles that are optimal for forming circuit wiring such as FPC or glass substrate, and excellent in migration resistance, conductive properties, and low-temperature sinterability, and a method for producing the same are provided. Is.

  This inventor examined in detail about the conductive particle for anisotropic conductive films applicable to a highly accurate fine circuit. And the conductive particle suitable for it as a material which can form the circuit wiring to a board | substrate etc. finely and with high precision was examined. As a result, by setting the conductive particles for anisotropic conductive film of Patent Document 1 previously proposed to have a composition containing Cu, and further to a composition containing Sn, the variation in particle size is suppressed. It was possible to improve the conductive properties of the particles themselves.

  That is, the present invention relates to a component composition containing Ni as a main component and containing P, for example, spherical NiP microparticles comprising a component composition containing 1 to 15% by mass of P, and the component composition contains Cu. Precipitation spherical NiP fine particles. Further, the component composition is a reduced precipitation type spherical NiP fine particle characterized by containing 0.01 to 18% by mass of Cu.

  Furthermore, the present invention is a reduction precipitation type spherical NiP microparticle characterized by containing Sn in addition to the component composition containing Cu, for example, containing 0.05 to 10% by mass of Sn. It is a characteristic reduction precipitation type spherical NiP fine particle.

Preferably, the reduced precipitation-type spherical NiP fine particles of the present invention preferably have an average particle size d ₅₀ of 0.1 to 70 μm and a particle size distribution of [(d ₉₀ −d ₁₀ ) / d ₅₀ ] ≦ 0. 8 (d ₉₀ , d ₁₀ , d ₅₀ : particle diameters indicating 90% by volume, 10% by volume, and 50% by volume in the cumulative distribution curve). In this, by including the above-mentioned Cu, in particular an average particle size d ₅₀ is advantageous in the particle size distribution adjusted in a large diameter side of 1～70Myuemu. Further, the inclusion of Sn is advantageous for adjusting the particle size distribution particularly on the small diameter side where the average particle diameter d ₅₀ is 0.1 to 10 μm.

  Then, the present invention mixes a nickel salt aqueous solution, a mixed aqueous solution of a pH adjusting agent and a pH buffering agent, and a reducing agent aqueous solution containing phosphorus to cause reduction precipitation, so that spherical NiP microparticles containing P mainly containing Ni. A method for producing particles, wherein the aqueous solution of nickel salt contains Cu, and is prepared so as to have an alkaline pH of more than 7 when mixed to start reduction precipitation. This is a method for producing NiP fine particles. The aqueous nickel salt solution preferably contains Cu so that Ni / Cu = 4.0 to 10,000 in terms of molar ratio.

  Furthermore, the aqueous solution of nickel salt at the time of reduction precipitation contains Sn in addition to the above-mentioned Cu, and is prepared so that the pH at the time of starting the reduction precipitation becomes alkaline exceeding 7. This is a method for producing reduced precipitation spherical NiP. It is preferable that the aqueous solution of nickel salt at this time contains Sn that satisfies Ni / Sn = 2.0 to 2000 in terms of molar ratio.

  The reduced precipitation type spherical NiP microparticles containing Cu or further Sn of the present invention have a spherical shape. Therefore, when the particles are blended in a thermosetting or thermoplastic insulating resin film, the particles are aggregated. And the dispersibility is good, and short-circuiting between electrodes is suppressed when used for conductive particles of an anisotropic conductive film. Along with that, low connection resistance and high connection reliability can be obtained even in the connection between metal electrodes that are easy to form an oxide film such as an Al or Cr electrode, which has been difficult to obtain good connection reliability. Is possible.

  Furthermore, the spherical NiP microparticles of the present invention are Ni-based metal particles, so that they have excellent migration resistance and conductive properties, and exhibit a fine and uniform particle size. Alternatively, when circuit wiring such as a glass substrate is formed, the sinterability at low temperatures is good, and damage to the substrate can be reduced.

  A feature of the present invention is that, among the reduction precipitation type spherical NiP fine particles as shown in, for example, Patent Document 1, which is composed mainly of Ni and essentially contains at least P, which is a metalloid, includes Cu. It has been clarified that the inclusion of is effective in suppressing variation in particle size. Specifically, the Cu content is in a component composition of 0.01 to 18% by mass.

  In addition, the feature of the present invention is that it has been clarified that the same variation suppressing effect can be exhibited even when Sn is contained in the spherical NiP fine particles containing Cu.

The spherical NiP microparticles containing Cu or both elements of Cu and Sn as described above have an average particle diameter d ₅₀ of 0.1 to 70 μm and a particle size distribution of [(d ₉₀ -d ₁₀ ) / D ₅₀ ] ≦ 0.8, spherical NiP microparticles having a uniform particle size. At this time, the spherical NiP microparticles in which Cu is selected in both of the contained elements are excellent in the above-described variation suppressing effect on the large diameter side with an average particle diameter of 1 to 70 μm. And the spherical NiP fine particle containing Cu and Sn simultaneously is excellent in the said dispersion | variation suppression effect in the small diameter side whose average particle diameter is 0.1-10 micrometers especially.

  In producing the spherical NiP microparticles of the present invention, for example, an aqueous solution of a nickel salt containing Cu or Cu and Sn, a mixed aqueous solution of a pH adjusting agent and a pH buffer, and an aqueous reducing agent solution containing phosphorus. It is preferable to prepare such that the pH of the mixed aqueous solution that starts the reduction deposition becomes alkaline with a pH of more than 7. The aqueous solution of the nickel salt containing Cu preferably has a Cu amount adjusted so that Ni / Cu = 4.0 to 10,000 in terms of molar ratio. And if Sn is added to the aqueous solution of nickel salt containing Cu, it is desirable that the Sn amount is adjusted so that Ni / Sn = 2.0 to 2000 in terms of molar ratio.

  First, the spherical NiP microparticles of the present invention are based on a component composition that contains Ni as a main component and essentially contains P, for example, 1 to 15% by mass of P. About this, when using as an electrically conductive particle for anisotropic conductive films, as an effective method for imparting the necessary hardness and conductivity, the present inventor has a crystal structure in the center part of the particle, and a surface layer part. Discloses a spherical NiP fine particle having a structure in which an intermetallic compound is dispersed in an amorphous state.

  And, according to the method of Patent Document 1, this is an effective technique showing a certain effect for ensuring the uniformity of the particle size distribution. Among the particles, it was found that the addition of Cu in particular can further suppress the dispersion of the particles and improve the conductivity.

  The Cu content in the reduced precipitation type spherical NiP fine particles of the present invention is preferably 0.01 to 18% by mass. When the Cu content is less than 0.01% by mass, it is difficult to obtain the effect of suppressing particle variation. Further, when the Cu content exceeds 18% by mass, not only the particles are easily aggregated and the monodispersibility is easily impaired, but, for example, when applied to an anisotropic conductive film, a circuit board connected thereby. It is difficult to obtain particles having a size of, for example, 20 μm or less, which can be applied to the fine wiring of the above. More desirably, by using a component composition containing 0.40 to 17% by mass of Cu, it becomes easy to obtain metal microparticles with little variation in particle size and excellent conductivity.

  Further, in addition to the above-described reduced precipitation type NiP microparticles containing Cu, addition of Sn to this also has an effect of suppressing variation in particle size. In this case, the Sn content of the spherical NiP fine particles of the present invention is desirably 0.05 to 10% by mass. When the Sn content is less than 0.05% by mass, it is difficult to obtain the effect of suppressing particle variation, and it is difficult to obtain the benefit of the same effect on the small diameter side, which will be described later. On the other hand, when the Sn content exceeds 10% by mass, not only the particles become amorphous, but also monodisperse particles are difficult to obtain. More preferably, by using a component composition containing 0.25 to 5% by mass of Sn, it becomes easy to obtain metal microparticles with little variation in particle size and excellent conductivity.

The average particle size of Cu or reductive deposition type spherical NiP microparticles containing both elements of Cu and Sn of the present _invention, it is desirable to 0.1~70μm the value of _{d 50 (d 50:} cumulative distribution curve In this case, it is necessary to select the particle size according to the application. However, if the particle size is less than 0.1 μm, the particles are likely to aggregate, making handling very difficult. On the other hand, if the average particle size d ₅₀ exceeds 70 μm, it takes a long time to grow the particles, and it becomes difficult to obtain uniform particles efficiently. Preferably, it is 50 μm or less, further 30 μm or less. In addition, when exceeding 20 micrometers, as a material used for wiring formation, such as conductive particles for anisotropic conductive films, FPC, and a board | substrate, the functional use will become difficult.

Here, the spherical NiP microparticles of the present invention, for example when used as an anisotropic conductive film for the conductive particles, it is desirable that the 1~20μm the value of d _50. When this particle size is less than 1 μm, the height variation of fine wiring formed on a circuit board such as TCP, FPC, PWB, etc. cannot be buffered when anisotropic conductive connection is made, and contact becomes unstable, and connection reliability Sex is reduced. On the other hand, if d ₅₀ exceeds 20 μm, in the connection of fine wiring with a narrow pitch such that the wiring interval is several tens of μm, there is a possibility that the insulating property is lowered and stable connection reliability cannot be ensured. Therefore, in order to optimize the spherical NiP microparticles of the present invention particularly as the conductive particles for the anisotropic conductive film, the value of d ₅₀ is preferably 1 to 20 μm, and more preferably 1 to 10 μm. It is desirable that the particle size is arbitrarily selected according to the wiring interval and the shape of the electrodes connected by the anisotropic conductive film.

In the reduced precipitation type spherical NiP fine particles of the present invention in which d ₅₀ is in the range of 0.1 to 70 μm, the d ₅₀ is adjusted to the large diameter side of 1 μm or more, further 5 μm or more, and The effect of suppressing the variation in particle size at that time is when Cu of both contained elements of Cu or Sn is contained alone.

Next, even when the spherical NiP fine particles of the present invention are used as a material for forming circuit wiring such as FPC or a glass substrate, the average particle diameter d ₅₀ is arbitrarily selected according to the use. 1 to 10 μm is desirable. If d ₅₀ exceeds 10 μm, it may not be applicable to a fine wiring interval, and there is a concern that the sintering temperature at the time of forming circuit wiring rises and damages the substrate. On the other hand, if d ₅₀ is less than 0.1 μm, not only the handling of the particles becomes very difficult, but also the particles themselves are expensive, making it difficult to deal with mass production.

In the reduced precipitation type spherical NiP microparticles of the present invention in which the d ₅₀ is in the range of 0.1 to 70 μm, the d ₅₀ is adjusted to the small diameter side of 10 μm or less and further less than 5 μm. In addition, the effect of suppressing variation in particle size at that time is excellent when both elements of Cu and Sn are contained.

Next, the reduced precipitation type spherical NiP fine particles of the present invention are also characterized by a uniform particle size distribution. When the particle size distribution is [(d ₉₀ -d ₁₀ ) / d ₅₀ ]> 0.8 (d ₉₀ , d ₁₀ : particle sizes indicating 90 vol% and 10 vol% in the integrated distribution curve), for example, different When the isotropic conductive connection is made, the number of particles involved in conduction is reduced, so that connection reliability may be lowered. Therefore, it is desirable that the particle size distribution given by this equation be as small as possible. However, since classification processing for reducing this value requires a great deal of cost, [(d ₉₀ −d ₁₀ ) of the particle size distribution is required. / D ₅₀ ] is preferably 0.8 or less. More preferably, it is 0.7 or less.

  A preferred method for producing the spherical NiP fine particles of the present invention will be described. First, in the patent document 1, the present inventor manufactures spherical NiP microparticles mainly containing Ni by mixing a nickel salt aqueous solution and a reducing agent aqueous solution containing P to reduce precipitation. An electrolytic reduction method was proposed. The basic principle of this reduction precipitation can also be used for the production of the spherical NiP fine particles of the present invention. In this case, what is important in the present invention is to add Cu ions to the aqueous nickel salt solution. It is. That is, Ni ions are reduced and Cu is reduced and precipitated by free electrons released by the oxidizing reaction of the reducing agent, and it is possible to obtain NiP microparticles containing Cu with a small variation in particle size.

  In addition, an important feature of the present invention is that Sn ions are added to the nickel salt aqueous solution to which the Cu ions are added, if necessary. As a result, during the reduction precipitation reaction, Sn is also co-deposited, and it is possible to obtain NiP microparticles containing Sn with a small variation in particle size.

  The above reaction mechanism will be described in detail. In the electroless reduction method employed by the present invention, immediately after mixing an aqueous solution of nickel salt and an aqueous reducing agent solution containing phosphorus, an oxidation reaction of a reducing agent containing phosphorus, that is, phosphinic acid, is first performed. Occur. As the oxidation reaction proceeds, phosphonate ions generated in the solution are accumulated. When the limit concentration is reached, phosphonate ions and free Ni ions are combined to form phosphones serving as nuclei of spherical NiP microparticles. Produces nickel acid. The phosphinic acid ion exhibits catalytic activity on the surface of the nucleus, that is, the Ni surface, and causes an oxidation reaction through a hydrogen elimination reaction, which is an elementary process of the reaction. By free electrons released during the oxidation reaction, Ni, Cu, and / or Sn metal ions are continuously reduced and deposited to form target spherical NiP microparticles.

  By the way, in general electroless Ni-P plating, a plating film is deposited in addition to an object to be plated, or a sulfur compound such as thiourea or Pb, Bi, Tl is used to prevent spontaneous decomposition of the plating solution. Heavy metal ions such as Sb are used as stabilizers. The above stabilizer is adsorbed preferentially over Ni to precipitates that cause spontaneous decomposition of the plating solution, and acts as a catalyst poison. And Sn and Cu are known as an element which reduces catalyst activity next to said heavy metal. In the production of the spherical NiP microparticles of the present invention, by adding Cu or Cu and Sn to an aqueous solution of nickel salt, the reaction of the catalyst poisons during the course of the electroless reduction process causes the subsequent reaction. It is judged that the production of nickel phosphonate can be suppressed. And as a result, when the component distribution in the cross section of the spherical NiP microparticles obtained by the production method of the present invention was analyzed, Cu or both ions of Cu and Sn were densely distributed in the center. (As shown in FE-SEM (field emission scanning electron microscope) images of FIGS. 3 to 6 and 9 to 13 described later).

  In addition, in the above action, as an appropriate condition particularly for suppressing variation in particle size, Cu is prepared in an aqueous solution of the nickel salt so that Ni / Cu = 4.0 to 10,000 in molar ratio. The time of addition was set. When the Ni / Cu ratio is lowered, the individual particle sizes themselves can be prepared larger, while the variation in the particle size distribution tends to be reduced. In addition, when the ratio is increased, individual particle sizes themselves can be prepared to be small, while variation in the particle size distribution tends to be reduced. In the above molar ratio, the theoretical Cu content contained in the obtained spherical NiP microparticles should be 100% when the reductive precipitation reaction when using an aqueous solution of nickel salt prepared to Ni / Cu = about 4.56 is completed 100%. Is 18% by mass when the P content is about 7% by mass. Moreover, if the reduction precipitation reaction when using an aqueous solution of nickel salt prepared to Ni / Cu = about 9999 is completed 100%, the theoretical Cu amount contained in the obtained spherical NiP microparticles is the same as the P content. At about 7% by mass, it is 0.01% by mass.

  In addition, when Sn is further added to an aqueous solution of nickel salt containing Cu, the effect of suppressing variation in particle size on the smaller diameter side is superior to that when Cu is added alone. Then, the time when Sn was prepared and added so that Ni / Sn = 2.0 to 2000 was set. When the Ni / Sn ratio is lowered, the individual particle sizes themselves can be prepared to be small, while the variation in the particle size distribution tends to be small. In addition, when the ratio is increased, individual particle sizes themselves can be prepared larger, while the variation in particle size distribution tends to be reduced.

  In these methods, another important factor is the adjustment of the pH when starting the reduction precipitation. By preparing it so that it becomes more than 7 alkaline, the precipitation reaction can proceed rapidly, and NiP microparticles containing Cu or Cu and Sn can be obtained efficiently. In addition to this action and effect, it is also possible to lower the P concentration in the central portion corresponding to the initial reaction of the present microparticles (as shown in FIGS. 3 to 6 and 9 to 13). This is also described in Patent Document 1 as an advantageous technique for improving the conductivity and hardness of the fine particles.

  In addition, even if it is the reduced precipitation type NiP microparticles containing Cu or Cu and Sn of the present invention provided by the above-mentioned method, as in Patent Document 1, it is a heat treatment for further imparting hardness, And / or a surface coating treatment such as Au for lowering the connection resistance may be performed.

(Example 1)
Nickel sulfate hexahydrate and copper sulfate pentahydrate are prepared so that the molar ratio of Ni and Cu is Ni / Cu = 239, dissolved in pure water, and an aqueous metal salt solution of 15 (dm ³ ). Produced. Next, sodium acetate was dissolved in pure water to a concentration of 1.0 (kmol / m ³ ), and sodium hydroxide was further added to prepare 15 (dm ³ ) of pH adjusted aqueous solution. And said metal salt aqueous solution and pH adjustment aqueous solution were stirred and mixed, and it was set as the mixed aqueous solution of 30 (dm < ³ >), and the value of 8.1 was shown when pH was measured. The mixed aqueous solution was heated and held at 343 (K) by an external heater while bubbling with N ₂ gas, and stirring was continued.

Next, 15 (dm ³ ) of a reducing agent aqueous solution in which sodium phosphinate was dissolved in pure water at a concentration of 1.8 (kmol / m ³ ) was prepared, and this was also heated to 343 (K) by an external heater. Then, the mixed aqueous solution of 30 (dm ³ ) and the reducing agent aqueous solution of 15 (dm ³ ) described above are mixed after being prepared so that the temperature becomes 343 ± 1 (K), and fine particles are formed by an electroless reduction method. Obtained.

After drying the microparticles obtained as described above, the particle size was measured with a particle size distribution meter by a laser diffraction scattering method. The average particle size d ₅₀ is 3.7 μm, d ₉₀ and d ₁₀ are 5.3 μm and 2.8 μm, respectively, and the particle size distribution given by the formula [(d ₉₀ −d ₁₀ ) / d ₅₀ ] is It was 0.68. The result of observing the shape of the particles with an SEM (scanning electron microscope) is as shown in FIG. 1 and was confirmed to be a monodispersed spherical shape. And the result of having analyzed the component composition of the microparticles was NiP microparticles containing 0.40% by mass of Cu as shown in Table 1 below.

(Example 2)
The ratio of nickel sulfate hexahydrate and copper sulfate pentahydrate was adjusted so that the molar ratio of Ni and Cu was Ni / Cu = 5, and the solution of metal salt aqueous solution, pH adjustment aqueous solution and reducing agent aqueous solution Fine particles were produced by the electroless reduction method in the same manner as in Example 1 except that the amount was 0.25 (dm ³ ). The pH of the mixed aqueous solution was 9.0.

The particle size distribution was confirmed by the laser diffraction scattering method. The average particle size d ₅₀ value was 8.9 μm, and the [(d ₉₀ −d ₁₀ ) / d ₅₀ ] value was 0.58. Spherical NiP fine particles shown in the SEM photograph were obtained. Moreover, when the cross-sectional observation sample of a particle was produced and the distribution of each element was observed with FE-SEM (field emission scanning electron microscope), as shown in FIGS. It was confirmed that Cu was densely distributed inside. The analysis results of the component composition confirmed that Cu was 14.36% by mass as shown in Table 1.

Example 3
The ratio of nickel sulfate hexahydrate and copper sulfate pentahydrate was adjusted so that the molar ratio was Ni / Cu = 39, and the pH buffer was sodium acetate and disodium maleate, Except for changing the concentration to 0.65 (kmol / m ³ ) and 0.175 (kmol / m ³ ) to prepare a pH adjusted aqueous solution, in the same manner as in Example 1, fine particles were obtained by an electroless reduction method. Manufactured. The pH of the mixed aqueous solution was 8.2.

As a result of measuring the particle size of the obtained microparticles with a particle size distribution meter of the laser diffraction scattering method, the average particle size d ₅₀ value was 67.1 μm, and the [(d ₉₀ −d ₁₀ ) / d ₅₀ ] value was 0. .51. Moreover, the result of observing the above-mentioned microparticles with an SEM is as shown in FIG. 7 and was confirmed to be a monodispersed spherical shape. The analysis result of the component composition confirmed that Cu was 2.750% by mass as shown in Table 1.

(Example 4)
According to Patent Document 1, a nickel salt aqueous solution to which no Cu is added and a mixed aqueous solution of sodium hydroxide 0.9 (kmol / m ³ ) and sodium acetate 1.0 (kmol / m ³ ) are each 0.25 (dm ³ ) Prepare and stir while heating from the outside, mix the two liquids to make a mixed aqueous solution, bubbling with N ₂ gas flowing, and adjusting the temperature of the mixed aqueous solution to 343 ± 1 (K) did.

On the other hand, a reducing agent aqueous solution in which sodium phosphinate is dissolved at a concentration of 1.8 (kmol / m ³ ) in pure water is prepared to 0.25 (dm ³ ), and this is also heated to 343 (K) by an external heater. Spherical NiP fine particles were obtained by the same method as in Example 1. When the particle size distribution was confirmed by a laser diffraction scattering method, the average particle size d ₅₀ value was 2.9 μm, and the [(d ₉₀ -d ₁₀ ) / d ₅₀ ] value was 0.76. And from the analysis result of the component composition of Table 1, Cu was confirmed only at the level of impurities (less than 0.001% by mass).

(Example 5)
Using nickel sulfate hexahydrate, copper sulfate pentahydrate and sodium stannate trihydrate so that Ni / Cu has a molar ratio of 24 and Ni / Sn has a molar ratio of 4.8. Fine particles were produced by the electroless reduction method in the same manner as in Example 1 except that it was prepared. The pH of the mixed aqueous solution was 9.6.

Then, when the particle size distribution was confirmed by the laser diffraction scattering method, the average particle size d ₅₀ value was 1.2 μm, and the [(d ₉₀ -d ₁₀ ) / d ₅₀ ] value was 0.67. Spherical NiP fine particles shown in the SEM photograph were obtained. Moreover, when the cross-sectional observation sample of a particle was produced and the distribution of each element was observed by FE-SEM, it was confirmed that Cu and Sn are distributed as FIGS. The analysis results of the component composition confirmed that Cu was 3.96 mass% and Sn was 0.67 mass% as shown in Table 1.

  The spherical NiP microparticles of the present invention having a uniform particle size are conductive particles such as anisotropic conductive pastes and heat seal connectors that require similar characteristics in addition to conductive particles for anisotropic conductive films. It can also be applied.

It is an electron micrograph which shows an example of the spherical NiP microparticles of the present invention. It is an electron micrograph which shows an example of the spherical NiP microparticles of the present invention. It is an electron micrograph which shows an example of the cross-sectional structure of the spherical NiP microparticles | fine-particles of this invention. It is a mapping photograph of Ni concentration distribution observed in the cross section of FIG. It is a mapping photograph of Cu concentration distribution observed in the cross section of FIG. It is a mapping photograph of P concentration distribution observed in the cross section of FIG. It is an electron micrograph which shows an example of the spherical NiP microparticles of the present invention. It is an electron micrograph which shows an example of the spherical NiP microparticles of the present invention. It is an electron micrograph which shows an example of the cross-sectional structure of the spherical NiP microparticles | fine-particles of this invention. 10 is a mapping photograph of Ni concentration distribution observed in the cross section of FIG. 9. It is a mapping photograph of Cu concentration distribution observed in the cross section of FIG. 10 is a mapping photograph of Sn concentration distribution observed in the cross section of FIG. 9. FIG. 10 is a mapping photograph of P concentration distribution observed in the cross section of FIG. 9. FIG.

Claims (12)

A reduction precipitation spherical NiP microparticle comprising a Ni-based spherical NiP microparticle having a component composition containing P, the component composition including Cu. 2. The reduced precipitation type spherical NiP fine particles according to claim 1, comprising a component composition mainly containing Ni and containing 1 to 15% by mass of P. The reduced precipitation type spherical NiP fine particles according to claim 1, wherein the component composition contains 0.01 to 18% by mass of Cu. The reduced precipitation type spherical NiP microparticles according to any one of claims 1 to 3, wherein the component composition contains Sn. 5. The reduced precipitation type spherical NiP fine particles according to claim 4, wherein the component composition contains 0.05 to 10 mass% of Sn. The average particle size _{d 50} is 0.1～70Myuemu, and the particle size distribution _{[(d 90 -d 10) /} d 50] ≦ 0.8 (d 90, d 10, d 50: In cumulative distribution curve, The reduced precipitation-type spherical NiP microparticles according to any one of claims 1 to 5, wherein the particle size is 90% by volume, 10% by volume, and 50% by volume. The average particle diameter d ₅₀ is 1 to 70 μm, and the particle size distribution is [(d ₉₀ −d ₁₀ ) / d ₅₀ ] ≦ 0.8 (d ₉₀ , d ₁₀ , d ₅₀ : 90 volumes in the integrated distribution curve. The reduced precipitation type spherical NiP fine particles according to any one of claims 1 to 3, wherein the particle diameter is 1%, 10% by volume, or 50% by volume. The average particle size d ₅₀ is 0.1 to 10 μm and the particle size distribution is [(d ₉₀ −d ₁₀ ) / d ₅₀ ] ≦ 0.8 (d ₉₀ , d ₁₀ , d ₅₀ : The reduced precipitation-type spherical NiP microparticles according to claim 4 or 5, wherein the particle size is 90% by volume, 10% by volume, and 50% by volume. A method of producing spherical NiP microparticles mainly containing Ni by mixing an aqueous solution of a nickel salt, a mixed aqueous solution of a pH adjusting agent and a pH buffering agent, and a reducing agent aqueous solution containing phosphorus, followed by reduction precipitation. A method for producing reduced precipitation type spherical NiP microparticles, characterized in that the aqueous solution of nickel salt contains Cu, and is prepared so as to be alkaline with a pH of more than 7 when mixing and starting reduction precipitation . The method for producing reduced precipitation-type spherical NiP microparticles according to claim 9, wherein the nickel salt aqueous solution contains Cu in a molar ratio of Ni / Cu = 4.0 to 10,000. The method for producing reduced precipitation-type spherical NiP microparticles according to claim 9 or 10, wherein the nickel salt aqueous solution contains Sn. The method for producing reduced precipitation-type spherical NiP microparticles according to claim 11, wherein the nickel salt aqueous solution contains Sn at a molar ratio of Ni / Sn = 2.0 to 2000.