CN102187405B

CN102187405B - Conductive powdery material, conductive material containing same, and method for manufacturing conductive particles

Info

Publication number: CN102187405B
Application number: CN200980140898XA
Authority: CN
Inventors: 松浦宽人; 小山田雅明
Original assignee: Nippon Chemical Industrial Co Ltd
Current assignee: Nippon Chemical Industrial Co Ltd
Priority date: 2008-10-14
Filing date: 2009-10-13
Publication date: 2013-01-02
Anticipated expiration: 2029-10-13
Also published as: JP4746116B2; CN102187405A; WO2010044388A1; KR20110069811A; KR101594639B1; TWI479508B; JP2010118334A; TW201021054A

Abstract

Provided is a conductive powdery material having excellent dispersibility and conductivity, even though the particle diameter of the conductive powdery material is smaller than the particle diameters of conventional conductive powdery materials. The conductive powdery material is composed of conductive particles each of which has a nickel film or a nickel alloy film formed on the surface of a core particle. The conductive particle has many protruding sections, each of which protrudes from the surface of the film, is formed continuous to the film, and has an aspect ratio of 1 or more. The ratio of the protruding sections having an aspect ratio of 1 or more is 40% or higher with respect to the total number of protruding sections. As for the conductive powdery material, the weight of the primary particles among the conductive particles is 85 wt% or more with respect to the weight of the conductive powdery material.

Description

Electric conduction powder and the manufacture method that comprises conductive material and the conductive particle of this electric conduction powder

Technical field

The present invention relates to electric conduction powder and the conductive material that comprises this electric conduction powder.In addition, the present invention relates to the manufacture method of conductive particle.

Background technology

The applicant had before proposed to have from the teeth outwards the conductivity electroless plating powder (with reference to patent documentation 1) of the microspike that is formed by nickel or nickel alloy.Electroless plating particle in this powder shows good conductivity by the effect of its microspike.This electroless plating particle by the water paste with spherical core be added on the electroless plating that comprises nickel salt, reducing agent, complexing agent etc. in bathing electroless plating operation (A operation) and in the water paste of spherical core, the constituent of electroless plating liquid is separated at least 2 kinds of liquid, simultaneously and through the time ground electroless plating operation (B operation) of adding respectively make.In this manufacture method, in the A operation, when the surface of core material particles forms the nickel overlay film, form the nuclear that generates starting point as projection.This nuclear is grown up in the B operation and is formed projection.The electroless plating particle that obtains so for example, can use well in the conductive adhesive that is used for the bonding opposed connecting circuit of conducting, anisotropic conductive film, anisotropic-electroconductive adhesive etc.

Outside this technology, the nickel core material of the core material particles surface attachment particle diameter 50nm that has proposed in patent documentation 2 at particle diameter 4 μ m then carries out the electroless plating of nickel, obtains thus having the method for the conductive particle of jut.But in the method, because a little less than the adaptation of core material particles and nickel core material, so the nickel dam on coating core material particles surface and the globality of jut are not enough, when conductive particle was exerted pressure, jut was damaged easily.In addition, it is very difficult to adhere to the 50nm nickel core material very less than its particle diameter on the core material particles surface uniform ground of particle diameter 4 μ m.This is because the aggegation each other of nickel core material is adhered to easier generation than the nickel core material on the core material particles surface.Its result, the nickel core material agglutinating particle that the particle diameter that forms of aggegation is large each other is often in the core material particles surface attachment, thereby forms easily very large jut.

In addition, along with more miniaturization of e-machine class in recent years, the circuit of electronic circuit is wide to become more and more less with spacing.Accompany with it, the electroless plating powder as using in above-mentioned conductive adhesive, anisotropic conductive film, the anisotropic-electroconductive adhesive etc. requires its particle diameter little.But, if contract short grained particle diameter, particle aggegation each other just occurs easily, therefore, although use the little particle of particle diameter, also can become large because aggegation makes apparent particle diameter (aggregate particle size).In addition, when using the little particle of particle diameter, aspect improving conductivity (reduction resistance) when using bulky grain difficulty.

The prior art document

Patent documentation

Patent documentation 1: TOHKEMY 2000-243132 communique

Patent documentation 2: TOHKEMY 2006-228474 communique

Summary of the invention

The problem that invention will solve

Therefore, the object of the present invention is to provide the further electric conduction powder that improves of electric conduction powder of the above-mentioned prior art of a kind of various Performance Ratios.

Solve the method for problem

In order to achieve the above object, the present inventor conducts in-depth research, found that, have and same degree dispersed and during more in the past than particle diameter was less conductive particle in the past in use, compare in the past more lengthwise by the shape that makes the projection that forms on its surface, and can suppress the decline of conductivity.

The invention that the present invention finishes with regard to being based on above-mentioned opinion, a kind of electric conduction powder is provided, it is characterized in that, it is to be formed with the electric conduction powder that the conductive particle by nickel or nickel alloy overlay film forms on the surface of core material particles, it is outstanding that above-mentioned conductive particle has a plurality of surfaces from above-mentioned overlay film, and and the draw ratio of this overlay film formation non-individual body is the jut more than 1, draw ratio is that the ratio of the above-mentioned jut more than 1 is more than 40% with respect to the quantity of whole juts, in above-mentioned electric conduction powder, the shared weight of primary particle is more than 85 % by weight with respect to the weight of electric conduction powder in the above-mentioned conductive particle.

In addition; the invention provides a kind of manufacture method of conductive particle; it is characterized in that; comprise: the A operation; the electroless plating bath that will comprise dispersant and nickel ion has the core material particles of noble metal to mix with the upper load in surface; when the surface of this core material particles formation nickel initial stage thin layer, the nickel ion concentration with respect to 1 liter is adjusted to this electroless plating of 0.0001～0.008 mol/L and bathes, and using the surface area summation is 1～15m ²This core material particles of amount; With the B operation, the resulting water paste that comprises the above-mentioned core material particles with nickel initial stage thin layer and contain above-mentioned dispersant in the A operation is maintained the pH scope of the dispersion effect that shows this dispersant, and in this water paste, add nickel ion and reducing agent that to be equivalent to the nickel amount of separating out hourly be the amount of 25～100nm through time ground, the nuclear particle of generating nickel in this water paste, and the nuclear particle that makes generation is attached on the above-mentioned core material particles, as starting point this nuclear particle is grown up with the nuclear particle that adheres to, the formation draw ratio is the jut more than 1.

The effect of invention

Electric conduction powder of the present invention, the size ratio of conductive particle that not only consists of this electric conduction powder is in the past little, and dispersed and conductivity is good.In addition, if manufacturing method according to the invention just can easily be made such electric conduction powder.

Description of drawings

Fig. 1 is the SEM picture of the conductive particle that obtains in embodiment 3.

Fig. 2 is the SEM picture of the conductive particle that obtains in comparative example 1.

Embodiment

Below, be described based on the preferred embodiment of the present invention.Electric conduction powder of the present invention is the electric conduction powder that is formed with nickel overlay film or nickel alloy overlay film (following these overlay films are generically and collectively referred to as " nickel overlay film ") on the surface of core material particles.One of feature that electric conduction powder of the present invention has is to have a plurality of from the outstanding jut in nickel overlay film surface.Below, this jut is described.

Forming a plurality of juts on the surface of electric conduction powder, as described in the background technology item of this specification, is technology known in this technical field.With respect to such background technology, in the present invention, as jut, adopt the jut of given shape, significantly different from existing electric conduction powder in this.Particularly, the jut in the electric conduction powder of the present invention is characterised in that draw ratio is more than 1.So-called draw ratio in this specification refers to the height H of jut and at the ratio of the jut width D of jut base portion, that is, is the value with the H/D definition.From this definition as can be known, draw ratio becomes the yardstick of the flexibility of jut, and this value is larger, means that the shape of jut is more elongated.

Have the draw ratio of this jut in the existing electric conduction powder of jut, headed by the patent documentation 1 of in the background technology item of this specification, narrating, in the limit known to the inventor, be not easy to be made for more than 1.Jut in the existing electric conduction powder has so-called short and thick shape (for example with reference to Fig. 2 described later).Relative therewith, the jut in the electric conduction powder of the present invention, for example shown in Figure 1 as described later, be the elongated protrusion that extends to general radial from particle surface.The present inventor etc. are more than 1 to studying rear judgement with the draw ratio of jut by making this value, and namely more elongated than in the past by the shape that makes jut, it is very high that conductivity just becomes.Its reason can think, when using electric conduction powder conduction electrode of the present invention, at the thin oxidation overlay film of electrode surface self-assembling formation or when having a mind to form the oxidation overlay film of electrode, if the draw ratio of jut is large, then breaks through easily this oxidation overlay film.Can think that in addition when using electric conduction powder to form anisotropic conductive film, if the draw ratio of jut is large, then the resin removing property just uprises, so conductivity uprises.In view of this reason, consider also that if the value of the draw ratio of jut is excessive then jut can be damaged, so the preferable range of draw ratio is 1.0～4.0, more preferably 1.0～3.5, more preferably 1.0～3.0.Conductive particle with the large jut of such draw ratio, for example, can be by method manufacturing described later.

When being conceived in the electric conduction powder each particle, it is desirability that the draw ratio of the jut that each particle has all satisfies above-mentioned scope, but the present inventor studies judgement, if the jut ratio that draw ratio satisfies above-mentioned scope is more than 40%, is preferably more than 45%, more preferably more than 50%, just can obtains sufficient conductivity with respect to whole bump counts.

The assay method of above-mentioned draw ratio is as described below.Use each particle in the electron microscope amplifying observation electric conduction powder.For 1 particle, at least 1 jut is measured its base portion length D and height H.At this moment, than take observe be present in particle central authorities in the image jut as determination object, preferably take the jut that is present in the particle periphery as determination object, this is very important for correct size up.Carry out such mensuration with at least 20 different particles as object.Resulting so a plurality of draw ratio data are carried out arithmetic average, should be worth as draw ratio.In addition, shown in Figure 1 as described later, because the cross section of jut is the little shape of anisotropy (for example circular), so the numerical value of the base portion length D of jut is less with the possibility that the particle viewing angle changes.

The draw ratio of jut as mentioned above, and the base portion length D of this jut itself and the height H of jut itself, for base portion length D, be preferably 0.05～0.5 μ m, be particularly preferably 0.1～0.4 μ m, for height H, be preferably 0.05～0.5 μ m, be particularly preferably 0.1～0.4 μ m.When the height H of the base portion length D of jut and jut was in this scope, conductivity further improved.

Draw ratio in each particle of electric conduction powder is the particle diameter that the quantity of the projection more than 1 also depends on particle, be that 3 μ m are when following at the particle diameter of particle as described later, from the aspect that the conductivity of electric conduction powder improves more, preferred 2～40 projections of per 1 particle are particularly preferably 2～20 projections.

The nickel overlay film of each jut in the electric conduction powder and coating core material particles forms non-individual body.Therefore, jut and nickel overlay film are made of nickel or nickel alloy equally.Here, so-called " non-individual body " means nickel overlay film and jut and all is made of same material, and jut is formed by single operation, and do not exist seam etc. to damage the such position of associative perception between nickel overlay film and jut.Therefore, for example form the nickel overlay film on the surface of core material particles, adhere to the nuclear particle that jut forms usefulness thereon, the jut that forms as the starting point of growing up with this nuclear particle, because jut is not formed by single operation, so be not included in the said non-individual body of the present invention.Because jut and nickel overlay film form non-individual body, so the intensity of jut is guaranteed that therefore, when using electric conduction powder, even exert pressure, jut can be not damaged yet.Its result can access good conductivity.

About the thickness of above-mentioned nickel overlay film, if it is excessively thin, electric conduction powder just is difficult to show sufficient conductivity, on the contrary, if blocked up, just easily from the core material particles sur-face peeling.From these viewpoints, the thickness of nickel overlay film (thickness at the non-existent position of jut) is preferably 0.01～0.3 μ m, more preferably 0.05～0.2 μ m.The thickness of nickel overlay film can dissolve from electric conduction powder by making nickel, and the nickel of dissolving is carried out quantitatively and obtains.In addition, according to the method, nickel overlay film just, and the nickel of jut also dissolves, but because the ratio that jut occupies in nickel is all is very low, so the nickel amount of jut can be ignored.

In the electric conduction powder of the present invention, the shape of each particle is preferably sphere.Here the grain shape of saying refers to remove the grain shape of jut.The particle that results from is for sphere and have jut, and the conductivity of electric conduction powder of the present invention uprises.

In the electric conduction powder of the present invention, the size of each particle can suitably be set according to the concrete purposes of electric conduction powder.The result of the present inventor's research judges, because the relation of the draw ratio of above-mentioned jut, the conductivity that the conductive particle particle diameter is little is high.Particularly, the conductive particle particle diameter is preferably 1～10 μ m, is particularly preferably 1～5 μ m, especially is preferably 1～3 μ m.In addition, the conductive particle particle diameter does not comprise the height of jut.The particle diameter of conductive particle can be measured by electron microscope observation.In addition, also can measure respectively particle diameter and the nickel overlay film thickness of core material particles, obtain from these values.

If the particle diameter of conductive particle is little, then there is the easily tendency of cohesion.If the generation aggegation then uses the anisotropic conductive film of conductive particle to have the defective that produces easily short circuit.In addition, wait processing to untie cohesion if implement pulverizings, then the nickel overlay film is peeled off, thus the reason of formation conductivity decline.Consider that from this viewpoint in electric conduction powder of the present invention, the dispersiveness that improves each particle is very important.Therefore, in the present invention, the weight that the primary particle in the conductive particle is shared is more than 85 % by weight with respect to the weight of electric conduction powder, is preferably more than 90 % by weight, more preferably more than 92 % by weight.In order to improve the dispersiveness of conductive particle, for example make conductive particle according to method described later and get final product.The shared weight of primary particle is measured according to following method.The 0.1g electric conduction powder is joined in the 100mL water, use ultrasonic homogenizer to disperse 1 minute.Then, measure particle size distribution by coulter counter method.Calculated the part by weight of primary particle by this result.

As previously mentioned, nickel overlay film and the jut in the conductive particle is made of same material.Particularly, consisted of by metallic nickel or nickel alloy.In nickel alloy, for example, comprise nickel-phosphor alloy.Nickel-phosphor alloy is the alloy that generates when using sodium hypophosphite as the reducing agent of nickel in electric conduction powder manufacturing described later.

In the electric conduction powder of the present invention, the surface of each particle can be formed by nickel or nickel alloy, and perhaps the surface of nickel or nickel alloy can coat with noble metal.As noble metal, preferred high metallic gold or the palladium of conductivity, particularly preferably gold.Coat by this, just can further improve the conductivity of electric conduction powder.The thickness that noble metal coats is generally about 0.001～0.5 μ m.This thickness can be calculated from addition and the chemical analysis of precious metal ion.

The manufacture method that is fit to of electric conduction powder of the present invention then, is described.This manufacture method roughly is divided into (1) will be used as raw material at the resulting particle of A operation in A operation and (2) that the core material particles surface forms nickel initial stage thin layer, form these 2 operations of B operation of purpose conductive particle.Below, these operations are described respectively.

In the A operation, mixing comprises the electroless plating bath of dispersant and nickel ion and at area load the core material particles of noble metal is arranged, thereby forms nickel initial stage thin layer on the surface of core material particles.The kind of core material particles is not particularly limited, and can use in organic substance and the inorganic matter any one.If consider electroless plating method described later, then core material particles is preferably the particle that can disperse in water.Therefore, core material particles preferably is in fact insoluble particle in water, more preferably bronsted lowry acids and bases bronsted lowry is not also dissolved or the particle of sex change.What is called can be disperseed in water, refers to by common dispersion means such as stirrings and can be formed in the outstanding turbid body that disperses in fact in the water.

The shape of core material particles is very large on the shape impact of purpose conductive particle.As discussed previously, because coat the thin thickness of the nickel overlay film on core material particles surface, so the shape of core material particles almost directly reflects the shape of conductive particle.Because the conductive particle sphere that is preferably as discussed previously is so the shape of core material particles also is preferably sphere.

When core material particles was sphere, the particle diameter of core material particles had a great impact the particle diameter tool of purpose conductive particle.As previously mentioned, owing to coat the thinner thickness of the nickel overlay film on core material particles surface, so the particle diameter of core material particles has directly reflected the particle diameter of conductive particle basically.Consider that from this viewpoint the particle diameter of core material particles can be same degree with the particle diameter of purpose conductive particle.Particularly, be preferably 1～10 μ m, be particularly preferably 1～5 μ m, especially be preferably 1～3 μ m.The particle diameter of core material particles can adopt with the same method of the particle diameter of conductive particle and measure.

The particle size distribution of the core powder that records by said method has one fixed width.In general, the width of powder granularity distribution represents by the coefficient of alteration shown in the following formula (1).

Coefficient of alteration (%)=(standard deviation/average grain diameter) * 100 ... (1)

This coefficient of alteration is large, and then the expression distribution is wide, and on the other hand, coefficient of alteration is little, and then expression has sharp grain size distribution.In the present invention, as core material particles, preferably using this coefficient of alteration is below 30%, is particularly preferably below 20%, especially is preferably the material below 10%.Its reason is when using conductive particle of the present invention as the conductive particle in the anisotropic conductive film, to have the advantage of the ratio that improves the effective participation connection.

Object lesson as the core powder, as inorganic matter, can enumerate metal (also comprising alloy), glass, pottery, silicon dioxide, carbon, metal or nonmetallic oxide (also comprising hydrate), comprise metal silicate, metal carbides, metal nitride, metal carbonate, metal sulfate, metal phosphate, metal sulfide, metal acid-salt, metal halide and the carbon etc. of aluminosilicate.As organic substance, can enumerate the thermoplastic resins such as natural fiber, natural resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylate, polyacrylonitrile, polyacetals, ionomer, polyester, alkyd resins, phenolic resins, urea resin, melamine resin, benzoguanamine resin, melamine resin, xylene resin, organic siliconresin, epoxy resin or diallyl phthalate resin etc.They can use separately, also can be used as the mixture more than 2 kinds and use.

In addition, other physical property of core material particles is not particularly limited, but when core material particles was resin particle, the defined K value of following formula (2) was preferably 10kgf/mm under 20 ℃ ²～10000kgf/mm ²Scope, and the recovery rate after 10% compression is preferably 1%～100% scope under 20 ℃.By satisfying these physics values, with electrode each other during crimping, can lesion electrode, and can fully contact with electrode.

F and S shown in the formula (2), be respectively and use slight compression testing machine MCTM-500 (manufacturing of (strain) Shimadzu Seisakusho Ltd.) when measuring, load value (kgf) and compression displacement (mm) during 10% compression of this microsphere, R is the radius (mm) of this microsphere.

Preferred its surface of core material particles has the capturing ability of precious metal ion, or it is carried out surface modification and makes it have the particle of the capturing ability of precious metal ion.Precious metal ion is preferably the ion of palladium or silver.Capturing ability with precious metal ion refers to can be with precious metal ion as chelate or salt and catch.For example, when having amino, imino group, amide groups, imide, cyano group, hydroxyl, nitro, carboxyl etc. on the surface of core material particles, the surface of this core material particles has the capturing ability of precious metal ion.When making the capturing ability that it has precious metal ion carrying out surface modification, can use for example method of Japanese kokai publication sho 61-64882 communique record.

Use this core material particles, make its area load noble metal.Particularly, core material particles is dispersed in the thin acidic aqueous solution such as palladium bichloride or this precious metal salt of silver nitrate.Thus, precious metal ion is caught on the surface of particle.The concentration of precious metal salt is at every 1m ²Granule surface area is 1 * 10 ^-7～1 * 10 ^-2The mole scope the time be sufficient.The core material particles that has caught precious metal ion is separated from system and wash.Then, core material particles is suspended in the water, to wherein adding reducing agent, carries out the reduction of precious metal ion and process.Thus, make carried noble metal on the surface of core material particles.As reducing agent, can use such as sodium hypophosphite, sodium borohydride, potassium borohydride, dimethylamine borane, hydrazine, formalin etc.

Precious metal ion is being caught before on the core material particles surface, the sensitization that also can implement tin ion is adsorbed on the particle surface is processed.For tin ion is adsorbed on the particle surface, for example, the core material particles that surface modification treatment is crossed is put in the stannous chloride aqueous solution, and the stirring stipulated time gets final product.

Mix with the electroless plating bath of nickel ion having applied like this core material particles of pre-treatment and having comprised dispersant.Non-electrolytic nickel plating bath is the solution take water as medium, as wherein contained dispersant, can enumerate for example non-ionic surface active agent, zwitterionic surfactant and/or water soluble polymer.As non-ionic surface active agent, can use the surfactant of the polyoxyalkylene ethers such as polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether.As zwitterionic surfactant, can use the surfactant of the sweet Lay bases such as the sweet Lay alkali of alkyl-dimethyl guanidine-acetic acid, the sweet Lay alkali of alkyl dimethyl carboxymethyl acetic acid, the sweet Lay alkali of alkyl dimethyl amion acetic acid.As water soluble polymer, can use polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethylcellulose etc.The use amount of dispersant depends on its kind, but in general, with respect to the volume of liquid (non-electrolytic nickel plating bath), is 0.5～30g/L.Particularly, if the use amount of dispersant is the scope of 1～10g/L with respect to the volume of liquid (non-electrolytic nickel plating bath), then the adaptation of nickel overlay film improves, and therefore considers it is preferred from this point.

Contained nickel ion can use water soluble nickel salt as its nickel source in the non-electrolytic nickel plating bath.As water soluble nickel salt, can use nickelous sulfate or nickel chloride, but be not limited thereto.Contained nickel ion concentration is preferably 0.0001～0.008 mol/L in the non-electrolytic nickel plating bath, is particularly preferably 0.0001～0.005 mol/L.

In electroless plating is bathed, except mentioned component, can also contain reducing agent.As reducing agent, can use the identical material of employed reducing agent in the reduction with above-mentioned precious metal ion.Reductant concentration during electroless plating is bathed is preferably 4 * 10 ^-4～2.0 mol/L are particularly preferably 2.0 * 10 ^-3～0.2 mol/L.

In non-electrolytic nickel plating bath, can also further contain complexing agent.By containing complexing agent, can play and suppress the advantageous effects that plating bath decomposes.As complexing agent, can enumerate organic carboxyl acid or its salt, for example citric acid, glycolic acid, tartaric acid, malic acid, lactic acid or gluconic acid or their alkali metal salts or ammonium salt.These complexing agents can use one kind or two or more.Complexing agent concentration during electroless plating is bathed is preferably 0.005～6 mol/L, is particularly preferably 0.01～3 mol/L.

Be not particularly limited having implemented the core material particles of pre-treatment and the method for non-electrolytic nickel plating bath mixing.For example, can in advance non-electrolytic nickel plating bath be heated to the temperature that to carry out the nickel ion reduction, and under this state, the core material particles of having implemented pre-treatment be put in the non-electrolytic nickel plating bath.By this operation, the nickel ion reduction, the nickel that is generated by reduction forms the initial stage thin layer on the core material particles surface.The initial stage thin layer is preferably formed as thickness 0.1～10nm, is particularly preferably 0.1～5nm.At this moment, jut not yet forms.

Emphasis in the A operation is the core material particles the relationship between quantities of nickel ion amount and input contained in the non-electrolysis plating bath.Particularly, the nickel ion concentration with respect to 1 liter is adjusted to 0.0001～0.008 mol/L, preferably is adjusted to the non-electrolytic nickel plating bath of 0.0001～0.005 mol/L, and using the surface area summation is 1～15m ², be preferably 2～8m ²The core material particles of amount.Thus, can form at an easy rate the initial stage thin layer with above-mentioned thickness.In addition, by making nickel ion amount and core material particles the relationship between quantities as mentioned above, can effectively prevent from forming the core material particles cohesion each other of initial stage thin layer.This is in the little situation of core material particles particle diameter, and for example particle diameter is effective especially in the following situation of 3 μ m.

The reduction of nickel ion is then carried out the B operation after finishing.The B operation is followed the A operation and is carried out, and does not carry out resulting core material particles with nickel initial stage thin layer in the A operation separated from liquid and waits operation.Therefore, in the water paste that comprises the core material particles with nickel initial stage thin layer, remaining have a dispersant that adds in the A operation.In the B operation, in comprising the A operation in resulting core material particles with nickel initial stage thin layer and the A operation in the water paste of employed dispersant, through the time ground add nickel ion and reducing agent.So-called " through the time ground add ", be to get rid of the meaning of quickly adding nickel ion and reducing agent, it refers to add continuously or intermittently nickel ion and reducing agent through the regular hour.At this moment, the interpolation of nickel ion and reducing agent opportunity can be in full accord, perhaps can add first nickel ion, then adds reducing agent again.Also can be reverse order.In addition, when add finishing, interpolation that can the FEFO nickel ion then finishes the interpolation of reducing agent again.Also can be reverse order.

As the nickel source of employed nickel ion in the B operation, can use with the A operation in identical nickel source, employed nickel source.Also be same for reducing agent.

In the B operation, by the reduction of nickel ion, at first in liquid, generate small nickel nuclear particle, this nuclear particle is attached on the surface of resulting core material particles with nickel initial stage thin layer in the A operation, make its growth with the nuclear particle that adheres to as starting point, form jut.By adopting the method, can effectively prevent particle cohesion each other, and can to form at an easy rate draw ratio be jut more than 1.Relative therewith, in the patent documentation 1 described in the background technology item of this specification, at first form overlay film on the surface of core material particles, form simultaneously the nuclear (the 1st operation) as the generation starting point of projection, then form projection (the 2nd operation) by this nuclear is grown up in subsequent handling.In the method, owing to must make the nickel ion in the 1st operation higher, so, take it as reason, just cause easily particle agglutination.In addition, be difficult to form the high jut of draw ratio.

In the reduction of nickel ion in the B operation, it is very important maintaining water paste in the pH scope that the dispersant (this dispersant also has remaining in the B operation) that adds in the A operation shows dispersion effect.Thus, can effectively prevent particle cohesion each other.The adjustment of pH can monitor the pH of water paste on one side, in hydrotropism slurry add the alkali such as the acid such as various inorganic acids or NaOH on one side.The adjusting range of pH adopts suitable value to get final product according to employed dispersant.When using that for example non-ionic surface active agent is as dispersant, preferably the pH with water paste maintains 5～10 scope.When using zwitterionic surfactant as dispersant, preferably the pH with water paste maintains 5～8 scope.When using water soluble polymer as dispersant, also preferred pH with water paste maintains 5～8 scope.

In the nickel ion reduction in the B operation, the nickel ion amount of adding in hydrotropism's slurry and reduction dosage also are very important.Thus, can successfully form the high jut core body of draw ratio.As actual conditions, in water paste, add through time ground that to be equivalent to the nickel amount of separating out hourly be 25～100nm, be preferably nickel ion and the reducing agent of the amount of 40～60nm.By adopting this adding conditional, separating out in nuclear particle than preferentially producing in the thin layer in the early stage of nickel forms the high jut core body of draw ratio easily.

When adding nickel ion and reducing agent, water paste can be heated to set point of temperature, thereby nickel ion is carried out smoothly by the reduction of reducing agent.When adding nickel ion and reducing agent, also can stir first water paste, so that the nickel of reduction evenly generates.

Like this, can obtain the purpose conductive particle.As required, this conductive particle can carry out reprocessing again.As reprocessing, can enumerate electroless plating metal working order or electroless plating palladium operation.By applying this operation, form gold plate or palladium coating on the surface of conductive particle.The formation of gold plate can be carried out according to existing known electroless plating method.For example, comprise tetrasodium ethylenediaminetetraacetate, disodium citrate and potassium auricyanide by in the outstanding turbid body of the water-based of conductive particle, adding, adjusted the electroless plating liquid of pH with NaOH, can form gold plate.

In addition, the formation of palladium coating can be carried out according to existing known electroless plating method.For example, in the aqueous suspension of conductive particle, add water-soluble palladium compounds such as containing palladium bichloride; The electroless palladium plating solution that the reducing agent such as hypophosphorous acid, phosphorous acid, formic acid, acetic acid, hydrazine, boron hydride, amido borane compound or their salt and complexing agent etc. are commonly used more as required, adds dispersant, stabilizer, pH buffer.Then, adjust pH with alkali such as the acid such as hydrochloric acid or sulfuric acid or NaOH, and carry out the reduced form electroless plating, can form palladium coating.As method for distinguishing, in the aqueous suspension of conductive particle, add palladium ion source, the complexing agent such as four ammino palladium salt and add as required dispersant, utilize the displacement reaction of palladium ion and nickel ion to carry out the displaced type electroless plating, also can form palladium coating.

In addition, the not phosphorous in fact or content of above-mentioned palladium coating is to the palladium coating below 3 % by weight, considers from the aspect of conductivity and electric reliability excellence and preferred.In order to form such coating, for example, when carrying out the displaced type electroless plating or carrying out the reduced form electroless plating, can use non-phosphorous reducing agent (for example formic acid).

As the dispersant that in reduced form electroless plating or displaced type electroless plating, uses, can use and the identical dispersant of illustrative dispersant in above-mentioned A operation.In addition, as non-electrolyte palladium plating solution commonly used, for example, can use the commercially available product that can obtain from Kojima Chemicals Co., Ltd., Japanese カニゼ Application Co., Ltd., central chemical Industry Co., Ltd etc.

As other reprocessing, also conductive particle can be offered the pulverizing process that uses the grinders such as ball mill.By offering this pulverizing process, combine with the reducing condition of above-mentioned nickel ion, the weight that primary particle occupies with respect to the weight of electric conduction powder can be set in above-mentioned scope.

Resulting like this conductive particle of the present invention can be well as such as anisotropic conductive film (ACF), heat-sealing connector (HSC), be used for electrode with display panels and be connected to and drive with employed electric conducting material on the circuit substrate of LSI chip etc.Particularly electric conduction powder of the present invention can be used as the electroconductive stuffing of conductive adhesive well.

Above-mentioned conductive adhesive can be preferably used as and is configured between 2 plate bases that form conductive substrate, and makes the anisotropic conductive adhesive of the bonding and conducting of above-mentioned conductive substrate by the heating pressurization.This anisotropic conductive adhesive comprises conductive particle of the present invention and adhesive resin.As adhesive resin, so long as insulating properties, and can as the material of adhesive resin, just can use with being not particularly limited.It can be in thermoplastic resin and the thermosetting resin any, and is preferably the material that shows adhesive property by heating.This adhesive resin is such as thermoplastic-type, thermosetting type, ultra-violet solidified type etc. are arranged.Show in addition in addition so-called half-thermosetting type, thermosetting type and ultra-violet solidified type compound etc. of the middle character of thermoplastic-type and thermosetting type.These adhesive resins can be in conjunction with as suitably being selected by the surface characteristic of the circuit substrate of adhering object etc. or type of service.The adhesive resin that particularly comprises thermosetting resin and consist of, the strength of materials after it is bonding is excellent, considers preferred from this point.

As adhesive resin, particularly, can enumerate to be selected from vinyl-vinyl acetate copolymer, carboxy-modified vinyl-vinyl acetate copolymer, ethylene-acrylic acid isobutyl ester copolymer, polyamide, polyimides, polyester, polyvingl ether, polyvinyl butyral, polyurethane, the SBS block copolymer, carboxy-modified SBS copolymer, the SIS copolymer, the SEBS copolymer, maleic acid modified SEBS copolymer, polybutadiene rubber, chloroprene rubber, carboxy-modified chloroprene rubber, styrene butadiene rubbers, isobutylene-isoprene copolymer, acrylonitrile-butadiene rubber (following table is shown NBR), carboxy-modified NBR, amine modification NBR, epoxy resin, epoxy radicals ester resin, acrylic resin, in phenolic resins or the organic siliconresin etc. a kind or material that will the resulting material of combination prepares as host more than 2 kinds.Wherein, as thermoplastic resin, the re-workability of styrene butadiene rubbers and SEBS etc. is excellent, and is therefore preferred.As thermosetting resin, be preferably epoxy resin.Wherein, high from bonding force, thermal endurance, electrical insulating property excellence, and melt viscosity is low, can consider with the advantage that low-pressure connects, and most preferably is epoxy resin.

As above-mentioned epoxy resin, so long as in 1 molecule, have the polynary epoxy resin of 2 above epoxy radicals, then can use general employed epoxy resin.As concrete example, can exemplify the novolac resins such as phenol novolac resin, cresols novolac resin; Make the polyatomic phenols such as bisphenol-A, Bisphenol F, bisphenol-A D, resorcinol, two dihydroxy diphenyl ethers, the polyalcohols such as ethylene glycol, neopentyl glycol, glycerol, trimethylolpropane, polypropylene glycol, the multiamino compounds such as ethylenediamine, three second tetramines, aniline, the polynary carboxyl compounds such as adipic acid, phthalic acid, M-phthalic acid etc. and chloropropylene oxide or 2-methyl epichlorohydrin react the epoxy resin of resulting glycidol fundamental mode.In addition, can enumerate the aliphat such as bicyclopentadiene epoxides, butadiene dimer diepoxide and cycloaliphatic epoxy resin etc.These epoxy resin can use separately or use mixing more than 2 kinds.

In addition, above-mentioned various adhering resins use the high sterling that has reduced foreign ion (Na or Cl etc.) or water-disintegrable chlorine etc., consider it is preferred from the viewpoint that prevents the ion migration.

The use amount of the conductive particle of the present invention in the anisotropic conductive adhesive with respect to 100 weight portion adhesive resin compositions, is generally 0.1～30 weight portion, is preferably 0.5～25 weight portion, more preferably 1～20 weight portion.Use amount by making conductive particle can suppress contact resistance and melt viscosity uprises in this scope, improve connection reliability, and fully guarantees the anisotropy that connects.

In above-mentioned anisotropic conductive adhesive, except above-mentioned conductive particle and adhesive resin, can also cooperate the known additive in this technical field, its use level also can be the well known range in this technical field.As other additive, can exemplify such as tackifier, reactive auxiliary agent, epoxy curing agent, metal oxide, light trigger, sensitizer, curing agent, vulcanizing agent, anti-deterioration agent, heat-resisting additive, heat conduction promoter, softening agent, colouring agent, various coupling agent or matal deactivator etc.

As tackifier, can enumerate such as rosin, rosin derivative, terpene resin, terpene phenolic resin, Petropols, coumarone-indene resin, phenylethylene resin series, isoprene resin, alkyl phenolic resin, xylene resin etc.Be crosslinking agent as reactive auxiliary agent, can enumerate such as polyalcohol, isocyanates, melamine resin, urea resin, methenamine class, amine, acid anhydrides, peroxide etc.As epoxy curing agent, so long as in 1 molecule, have the curing agent of 2 above reactive hydrogens, just can use with no particular limitation.As concrete curing agent, can enumerate polyamine compounds such as Diethylenetriamine, three second tetramines, m-phenylene diamine (MPD), dicyandiamide, daiamid; The organic acid anhydrides such as phthalic anhydride, methyl carbic anhydride, hexahydro phthalic anhydride, PMA acid anhydride; The novolac resins such as phenol novolac resin, cresols novolac resin etc.These curing agent can use separately, or use mixing more than 2 kinds.In addition, according to purposes and needs, also can use the potentiality curing agent.As operable potentiality curing agent, can enumerate salt such as imidazoles, hydrazides class, boron trifluoride-amine complex, sulfosalt, amine acid imide, polyamines, dicyandiamide etc. and their modifier.These curing agent can use separately, or use as the mixture more than 2 kinds.

Above-mentioned anisotropic conductive adhesive, usually use widely used manufacturing installation in those skilled in the art, cooperate conductive particle of the present invention and adhesive resin and curing agent as required and various additive, and when adhesive resin is thermosetting resin, make by in organic solvent, mixing, and when it is thermoplastic resin, by under the temperature more than the adhesive resin softening point, particularly preferably be about about 50～130 ℃, more preferably about 60～110 ℃ of left and right sides melting mixings and making.Resulting like this anisotropic conductive adhesive can be coated with use, also can form membranaceous use.

Embodiment

Below, illustrate in greater detail the present invention by embodiment.But scope of the present invention is not subjected to the restriction of these embodiment.

[embodiment 1～4]

(1) A operation

To have in the particle diameter shown in the table 1, true specific gravity is that 1.1 spherical styrene-silicon dioxide compound resin [(strain) Japanese catalyst manufacturing, trade name ソリオスタ one] is as core material particles.Stir on one side, on one side its 40g is put in the 400mL conditioning agent aqueous solution (" CLEANER-CONDITIONER 231 " that the ROHM AND HAAS electronic material is made).The concentration of the conditioning agent aqueous solution is 40ml/L.Then, under liquid temperature 60 ℃ apply ultrasonic wave on one side, stirred 30 minutes on one side, carry out surface modification and the dispersion treatment of core material particles.Filtering solution will carry out the slurry that core material particles that the pulp-water of once remaking washes forms 200mL.In this slurry, drop into the 200ml stannous chloride aqueous solution.The concentration of this aqueous solution is 5 * 10 ^-3Mol/L.Stirred at normal temperatures 5 minutes, and made tin ion be adsorbed on the lip-deep sensitization of core material particles and process.Continue filtering solution, carry out 1 recasting pulp-water and wash.Then, core material particles is formed the slurry of 400ml, and maintain 60 ℃.Stir slurry in conjunction with ultrasonic wave on one side, Yi Bian add the palladium chloride aqueous solution of 2mL 0.11mol/L.Former state was kept this stirring 5 minutes, carried out palladium ion is caught in the lip-deep activation processing of core material particles.

Then, the formed electroless plating of the aqueous solution that 3L has been dissolved kind shown in the sodium hypophosphite, the nickel sulfate hexahydrate compound shown in the table 1, table 1 of sodium tartrate, the 5.4g/L of 20g/L and concentration dispersant is bathed and is warming up to 70 ℃, and to the load that drops into the amount of Table 1 during this electroless plating is bathed the core material particles of palladium, beginning A operation.Wherein, the particular content of the dispersant shown in the table 1 is as shown in table 2.Stirred 5 minutes, and confirmed that bubble hydrogen stopped to produce, finish the A operation.

(2) B operation

Use respectively 300mL 224g/L nickel sulfate solution and contain the 210g/L sodium hypophosphite and the mixed aqueous solution of 80g/L NaOH, and use measuring pump that they are added in the slurry of resulting core material particles in the A operation continuously separately, beginning electroless plating B operation.Interpolation speed all is 2.5mL/ minute.The actual conditions of this operation is as shown in table 3.After adding all liq, Yi Bian keep 70 ℃ temperature, Yi Bian continue to stir 5 minutes.Then filter liquide, and washing and filtering thing 3 times, then dry in 100 ℃ vacuum drier, obtain having the conductive particle of nickel-phosphor alloy overlay film.The scanning electron microscope (SEM) that in Fig. 1, is illustrated in the conductive particle that obtains among the embodiment 3 as.From this figure as can be known, nickel overlay film and the jut in the conductive particle becomes non-individual body.

[embodiment 5～23]

Except carry out A operation and B operation with the condition shown in table 1 and the table 3, and embodiment 1 operates equally, obtains conductive particle.Wherein, in the B of embodiment 19 operation, make the addition of the mixed aqueous solution that comprises nickel sulfate solution, sodium hypophosphite and NaOH be respectively 230mL.In addition, in the B of embodiment 20 operation, make the addition of the mixed aqueous solution that comprises nickel sulfate solution, sodium hypophosphite and NaOH be respectively 390mL.In addition, make that the addition of the mixed aqueous solution that comprises nickel sulfate solution, sodium hypophosphite and NaOH of embodiment 21 to 23 and rate of addition are respectively 150,225,600mL; 1.3,1.9,5.0mL/ minute.As operation, obtain having the conductive particle of nickel-phosphor alloy overlay film.

[embodiment 24]

The non-electrolyzing gold plating bath that preparation is comprised of citric acid-2Na of EDTA-4Na, the 10g/L of 10g/L and the potassium auricyanide of 2.9g/L (be 2.0g/L as Au).Should be heated to 79 ℃ by the gold plating bath with 2 liters, it was added the conductive particle that 10g obtains while stirring in embodiment 2.Carrying out electroless plating at particle surface thus processes.Processing time is 20 minutes.After processing finished, filter liquide was starched the filtrate recasting 3 times.Then, dry with 110 ℃ vacuum drier.Such as in this wise operation, applied gold-plated coating at the nickel-phosphor alloy overlay film and processed.

[embodiment 25～27]

Preparation is by the citric acid 2Na of EDTA-2Na, the 10g/L of 10g/L and the four ammino palladium hydrochloride (Pd (NH of 20g/L ₃) ₄Cl ₂) electroless palladium plating solution that forms of solution (be 2g/L as palladium), 100ppm carboxymethyl cellulose (molecular weight 250000, degree of etherification falling 0.9).0.65 liter of this palladium plating solution (embodiment 25), 1.3 liters of these palladium plating solutions (embodiment 16), 2.6 liters of these palladium plating solutions (embodiment 27) are heated to 70 ℃, it is added the conductive particle that 10g obtains while stirring in embodiment 2.Thus, particle surface having been carried out the displaced type electroless plating processes.Processing time is 60 minutes.After processing finished, filter liquide was starched the filtrate recasting 3 times.Then, dry with 110 ℃ vacuum drier.Such as in this wise operation, applied the plating palladium at the nickel-phosphor alloy overlay film and coated processing.In the palladium overlay film, do not comprise phosphorus.

[comparative example 1～7]

Except carry out A operation and B operation with the condition shown in table 1 and the table 3, and embodiment 1 operates equally, obtains having the conductive particle of nickel-phosphor alloy overlay film.Wherein, in the B of comparative example 3 operation, make the addition of the mixed aqueous solution that comprises nickel sulfate solution, sodium hypophosphite and NaOH be respectively 230mL.In addition, make that the addition of the mixed aqueous solution that comprises nickel sulfate solution, sodium hypophosphite and NaOH of comparative example 5 to 6 and rate of addition are respectively 380,1200mL; 0.3,10.0mL/ minute.The SEM picture of the conductive particle that in Fig. 2, obtains in the expression comparative example 1.

[comparative example 8]

The conductive particle that makes in comparative example 2 applies with embodiment 24 same gold-plated coatings and processes.

[evaluation of physical property]

Measure respectively and estimate thickness, the surface state of thickness, the palladium overlay film of the particle diameter of the conductive particle that in embodiment and comparative example, obtains, the thickness of nickel overlay film, golden overlay film, adaptation and the conductivity of nickel overlay film.In addition, also estimated the adaptation of golden overlay film to having applied gold-plated particle, the particle that has applied the plating palladium has also been estimated the adaptation of palladium overlay film.Each evaluation of physical property is undertaken by following method.In addition, the ratio that the draw ratio, draw ratio of measuring respectively jut take said method occupied as the ratio of the jut more than 1 and the primary particle in electric conduction powder, the particle diameter of conductive particle.These results of expression in table 4 and table 5.

[thickness of nickel overlay film]

Flood conductive particle in chloroazotic acid, dissolving nickel overlay film carries out icp analysis or chemical analysis to the overlay film composition, is calculated the thickness of nickel overlay film by following (1), (2).

A＝[(r+t) ³-r ³]d ₁/r ³d ₂ (1)

A＝W/(100-W) (2)

In the formula, r is the radius (μ m) of core material particles, and t is the thickness of nickel overlay film, d ₁The proportion of nickel overlay film, d ₂Be the proportion of core material particles, W is the containing ratio (% by weight) of nickel.

[thickness of golden overlay film-palladium overlay film]

Flood conductive particle in chloroazotic acid, dissolving gold or palladium overlay film and nickel overlay film carry out icp analysis or chemical analysis to the overlay film composition.Then, calculated the thickness of gold or palladium overlay film by following (3) and (4).

B＝[(r+t+u) ³-(r+t) ³]d ₃/(r+t) ³d ₄ (3)

B＝X(100-X) (4)

In the formula, u is the thickness of gold or palladium overlay film, d ₃The proportion of gold or palladium overlay film, d ₄Be the proportion of Ni product, X is the containing ratio (% by weight) of gold or palladium.Here, the proportion d of Ni product ₄The use calculating formula is calculated.Proportion uses the calculating formula of following (5) to calculate.

d ₄＝100/[(W/d ₁)+(100-W)/d ₂] (5)

In the formula, d ₁The proportion of nickel overlay film, d ₂Be the proportion of core material particles, W is the containing ratio (% by weight) of nickel.

[surface state]

Use SEM that conductive particle is amplified 30000 times, observe 10 visuals field, calculate the number mean value of the jut that 1 conductive particle has.10～100 be evaluated as the △ that is evaluated as below zero, 10.In addition, the nickel average evaluation of unusually separating out for *.What is called is separated out unusually, for example, refers to that nickel is not to separate out on the core material particles surface, but situation about in liquid, separating out separately etc.

[adaptation of overlay film]

In the beaker of 100mL, add the zirconium oxide bead of 2g conductive particle and 90g diameter 1mm, add again 10mL toluene.After 10 minutes, separation of oxygenated zirconium pearl and slurry make it dry with the agitating device stirring.Use SEM that dried conductive particle is amplified 2000 times, observe 10 visuals field, calculate by the mean value that stirs the stripping film number that produces.The stripping film number is less than 10 zero, 10～30 the △ that is evaluated as of being evaluated as, greater than 30 be evaluated as *.

[conductivity]

Mix 100 parts of epoxy resin, 150 parts of curing agent, 70 parts of toluene, preparation insulating properties adhesive.Cooperate therein 15 parts of conductive particles, obtain thickener.Use rod to be coated with machine, this thickener is coated on the polyester film of silicone-treated, and makes its drying.Use resulting coated film, use aluminium-vapour deposition whole glass be connected 50 μ m spacings and form connection between the polyimide film substrate of copper pattern.Then, measure interelectrode conducting resistance, estimate thus the conductivity of conductive particle.Resistance value is the following △ that are evaluated as that are evaluated as zero, 2～5 Ω of 2 Ω, being evaluated as more than 5 Ω *.In addition, in table, also charge in the lump and have or not short circuit to occur.

[table 1] A operation

[table 2]

A	Polyethylene glycol
		B	Polyoxyethylene alkyl ether
C	Polyoxyethylated alkyl phenol
		D	Alkyl dimethyl carboxymethyl acetic acid betaine
E	Alkyl dimethyl acetic acid betaine
		F	Alkyl dimethyl aminoacetic acid betaine
G	Polyvinyl alcohol
		H	Polyvinylpyrrolidone
I	Hydroxyethylcellulose

[table 3] B operation

The scope of ※ pH is from dripping beginning up to dripping the passing that finishes

By the result shown in table 4 and the table 5 as can be known, the draw ratio that resulting electric conduction powder in the comparative example, resulting electric conduction powder among each embodiment (the present invention's product) are judged as jut is high, and the ratio that primary particle occupies is high.In addition, than the electric conduction powder that obtains in comparative example, resulting electric conduction powder also is judged as the adaptation height of conductivity height and nickel overlay film among each embodiment.

Utilizability on the industry

The size ratio of conductive particle that electric conduction powder of the present invention not only consists of this electric conduction powder is in the past little, and dispersed and conductivity is good.In addition, if manufacturing method according to the invention just can easily be made such electric conduction powder.

Claims

1. electric conduction powder is characterized in that:

It is to be formed with the electric conduction powder that the conductive particle by nickel or nickel alloy overlay film forms on the surface of core material particles,

Described conductive particle have a plurality of surfaces from described overlay film outstanding and and this overlay film draw ratio of forming non-individual body be 1.0～4.0 jut, draw ratio is that the ratio of 1.0～4.0 described jut is more than 40% with respect to the quantity of whole juts, in described electric conduction powder, the shared weight of primary particle is more than 85 % by weight with respect to the weight of electric conduction powder in the described conductive particle.

2. electric conduction powder as claimed in claim 1 is characterized in that:

The average grain diameter of described core material particles is 1～3 μ m.

3. electric conduction powder as claimed in claim 1 or 2 is characterized in that:

The surface that comprises the described overlay film of described jut with gold or palladium.

4. conductive material is characterized in that:

Comprise each described electric conduction powder and insulative resin in the claim 1～3.

5. the manufacture method of a conductive particle is characterized in that, comprising:

The A operation; the electroless plating bath that will comprise dispersant and nickel ion has the core material particles of noble metal to mix with the upper load in surface; when the surface of this core material particles formation nickel initial stage thin layer; nickel ion concentration with respect to 1 liter is adjusted to this electroless plating of 0.0001～0.008 mol/L and bathes, and using the surface area summation is 1～15m ²This core material particles of amount; With

The B operation, the resulting water paste that comprises the described core material particles with nickel initial stage thin layer and contain described dispersant in the A operation is maintained the pH scope of the dispersion effect that shows this dispersant, and in this water paste, add nickel ion and reducing agent that to be equivalent to the nickel amount of separating out hourly be the amount of 25～100nm through time ground, the nuclear particle of generating nickel in this water paste, and the nuclear particle that makes generation is attached on the described core material particles, as starting point this nuclear particle is grown up with the nuclear particle that adheres to, the formation draw ratio is the jut more than 1.

6. manufacture method as claimed in claim 5 is characterized in that:

So that becoming the mode of 0.1～10nm, the thickness of nickel initial stage thin layer carries out operation A.

7. such as claim 5 or 6 described manufacture methods, it is characterized in that:

As described dispersant, use non-ionic surface active agent, zwitterionic surfactant or water soluble polymer.