JP2000322936A - Conductive micro particle and conductive connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micro particle having a metallic coating layer where crack or wrinkle is not developed and no break-away or separation from a resin base material particle, by forming a metallic coating layer around a complex layer that is composed of metal and resin and is formed in and/or around the resin base material particle. SOLUTION: In this conductive micro particle, an interface complex layer 12 composed of metal and resin formed around the resin base material particle 11, and further a metallic coating layer 13 is formed around it. Thickness of the interface complex layer 12 is 0.01 to 1000 μm, preferably 0.1 to 10 μm. The interface complex layer 12 has a complex structure of the metal and the resin, may be a structure where the metal and the resin mutually intricate, and may be a structure where micro-spherical metals are dispersed in the resin. A gradient material structure is preferable where metal concentration increases from the inside to the outside of the interface complex layer 12. In addition, thickness of the metallic coating layer 13 is 0.05-100 μm, preferably 0.1-50 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to conductive fine particles used for connection between electrodes and a conductive connection structure using the conductive fine particles.

[0002]

2. Description of the Related Art In electronic products such as a liquid crystal display, a personal computer, and a portable communication device, the electrical connection between an electronic component or an electronic component element and an electrode substrate, such as flip-chip bonding or connection using a ball grid array (BGA). In connection, metal fine particles made of solder, nickel, copper, or the like have been used. However, these metal fine particles have the drawback of being too hard or poor in elasticity, and the conductive connection structure using these metal fine particles has cracks in the connection part when a cooling / heating cycle test is performed. There were problems such as easy occurrence.

In order to solve such a problem, an anisotropic conductive film is prepared by using conductive fine particles having a metal coating layer provided around the resin base particles by electroless plating. It has been proposed to use a conductive film for conductive connection between an electronic component or an electronic component element and an electrode substrate. (Japanese Patent Laid-Open No. 61-
JP-A-664882, JP-A-61-277105, JP-A-63-190204, JP-A-01-2
No. 42782 and JP-A-09-137289). However, the conventional conductive fine particles provided with a metal coating layer around the resin base particles by electroless plating or electrolytic plating have the following problems.

That is, in the conventional conductive fine particles, the adhesion between the metal coating layer made of nickel, gold or the like and the resin base material particles is insufficient. When pressure was applied between the substrates or shear stress was applied, the metal coating layer was easily peeled off or detached from the surface of the resin base material particles.

[0005] Further, when a thermal cycle test is performed using a conventional conductive connection structure using conductive fine particles,
Cracks and wrinkles were easily generated in the metal coating layer. Further, since the conventional conductive fine particles have the above-described problems, the resistance value of the conductive fine particles increases at the junction of the conductive connection structure, and the obtained conductive connection structure has a sufficient reliability. Did not have.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has as its object to provide conductive fine particles having a metal coating layer which does not crack or wrinkle and which does not peel off or detach from resin base particles. Aim. Another object is to provide a highly reliable conductive connection structure manufactured using the conductive fine particles.

[0007]

According to the present invention, a composite layer comprising a metal and a resin is formed inside and / or around resin base particles, and a metal coating layer is further formed around the composite layer. Conductive fine particles. Hereinafter, the present invention will be described in detail.

The resin base particles used for the conductive fine particles of the present invention include particles made of a resin material or an organic / inorganic hybrid material. Examples of the resin material include linear polymers such as polystyrene, polymethyl methacrylate, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polysulfone, polycarbonate, and polyamide; divinylbenzene, hexatriene, divinyl ether,
Divinyl sulfone, diallyl carbinol, alkylene diacrylate, oligo or polyalkylene glycol diacrylate, oligo or polyalkylene glycol dimethacrylate, alkylene triacrylate, alkylene tetraacrylate, alkylene trimethacrylate, alkylene tetramethacrylate, alkylene bisacrylamide, alkylene bismethacryl Amide,
Reticulated polymers obtained by polymerizing an acrylic-modified polybutadiene oligomer at both ends alone or with another polymerizable monomer; and thermosetting resins such as phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, and urea formaldehyde resin. .

As the organic / inorganic hybrid material, for example, a copolymer of (meth) acrylate having a silyl group in a side chain with a vinyl monomer such as styrene or methyl methacrylate is prepared, and then the silyl group is subjected to a condensation reaction. What was made; tetraethoxysilane, triethoxysilane, diethoxysilane, etc. in the presence of an organic polymer
Gel-reacted ones include those obtained by performing a sol-gel reaction of tetraethoxysilane, triethoxysilane, diethoxysilane, and the like, and then firing at low temperature to leave organic components.

The method for synthesizing the resin material and the organic / inorganic hybrid material is not particularly limited, and a conventionally known synthesis method such as a suspension polymerization method, a seed polymerization method, a dispersion polymerization method, and a Steber method by a sol-gel reaction is used. It may be appropriately selected and used.

The shape of the resin base particles is spherical or spheroidal. The average particle diameter of the resin base particles, that is, the diameter when the resin base particles are spherical, and the long diameter when the resin base particles are spheroidal are preferably from 1 to 1000 μm, more preferably from 2 to 500 μm. Average particle size is 1
If it is less than μm, it is difficult to form a uniform coating layer on the resin base particles, and if it is more than 1000 μm, it is difficult to bond the fine electrodes. The average particle diameter is a value obtained by observing and measuring 300 arbitrary resin base material particles with an electron microscope.

The coefficient of variation (CV value) of the particle size distribution of the resin base particles is preferably 5% or less, more preferably 3% or less. If the CV value is more than 5%, the particle diameter of the resin base particles becomes uneven. Therefore, when the electrodes are connected via the conductive fine particles produced using the resin base particles, the electrodes are involved in the connection. Undesired conductive fine particles may be generated, and a leak phenomenon may occur between adjacent electrodes.

The CV value is defined by the following formula (1): CV value (%) = (σ / Dn) × 100 (1) (where σ represents the standard deviation of the particle diameter) , Dn represent the number average particle diameter). The standard deviation and the number average particle diameter are values obtained by observing and measuring 300 arbitrary resin base particles with an electron microscope.

The resin base particles may have pores near the surface or may not have the pores. First, the case where the resin base particles have no pores will be described with reference to the drawings.

In this case, the conductive fine particles of the present invention can
As shown in the cross-sectional views of (a) and (b), an interface composite layer 12 made of a metal and a resin is provided around resin base particles 11.
Is formed, and a metal coating layer 13 is further formed around it. The thickness of the interface composite layer 12 is 0.01 to
1000 μm is preferable, and 0.1 to 10 μm is more preferable.

The interface composite layer 12 has a composite structure of a metal and a resin. The composite structure may be a structure in which a metal and a resin are intertwined with each other, or a structure in which fine spherical metals are dispersed in a resin. Further, these composite structures may be mixed. In such an interface composite layer, a gradient material structure in which the metal concentration increases from the inside to the outside of the interface composite layer 12 is preferable. By adopting such a gradient material structure, the inner portion of the interface composite layer has a high resin ratio, and there is no difference in composition with the resin base particles. This is because the outer portion of the composite layer has a high metal ratio and can form a strong bond with the metal coating layer.

The metal constituting the interface composite layer 12 includes:
For example, groups VIII, IB, IVB in the periodic table
Metals belonging to a group or the like. Of these, V
Group III is preferably palladium or platinum, and Group IB is preferably gold, silver or copper, and more preferably palladium.

Further, a metal constituting the interface composite layer 12 includes:
It is preferable that the same metal is contained in the metal forming the metal coating layer 13 described later. By using the same metal, the adhesion strength between the interface composite layer and the metal coating layer can be increased.

The method for forming the interface composite layer 12 is as follows.
For example, the following method can be used. On the surface of the resin substrate particles, apply a thermosetting resin or a photocurable resin before curing, and after curing this, treat the resin substrate particles with an alkali solution, an acid solution or an oxidizing agent solution, A method in which a palladium chloride solution is brought into contact with the cured resin layer, and then reduced with hydrochloric acid to precipitate metallic palladium (hereinafter referred to as Method 1).
It is).

Examples of the thermosetting resin or photocurable resin include bisphenol A type epoxy, novolak type epoxy, resol and the like containing an amine-based, amide-based or imidazole-based heat-curing agent and a photocationic-based curing agent. Epoxy resins such as type epoxy, alicyclic epoxy, and acryl-modified epoxy. These resins may be used alone or in combination of two or more. Further, it may be used by blending with another thermosetting resin. As the other thermosetting resin, for example, acrylate resin,
Examples include polyester resin, polysulfone, polyphenylene oxide, cellulose acetate, and butyral resin.

The surface of the resin base particles is coated with a thermosetting resin or a photocurable resin in which nano-sized palladium microspheres are dispersed, and after curing, the palladium microspheres are dispersed and hardened. A method (method 2) of treating the resin layer with an alkali solution, an acid solution or an oxidizing agent solution can also be used. Here, after the treatment with the alkali solution, the acid solution or the oxidizing agent solution is completed, a palladium chloride solution may be further brought into contact with the solution, and then reduced with hydrochloric acid to deposit metal palladium on the surface.

As the thermosetting resin or the photocurable resin, for example, the same resins as those used in the method 1 can be used. Here, palladium is used as an example for the interface composite layer 1.
Although the method of forming No. 2 has been illustrated, the metal that can be used in these methods is not limited to palladium.

Next, the case where the resin base particles have an opening near the surface will be described.

In this case, in the conductive fine particles of the present invention, a composite layer composed of a metal and a resin is formed inside the resin base particles, and a metal coating layer is further formed around the composite layer. In the conductive fine particles, since the resin base particles have openings near the surface, metal can enter the openings. Therefore, a composite layer composed of a metal and a resin can be formed inside the resin base particles.

As a method for producing the resin base particles having an opening at a portion close to the surface, for example, the following method can be used. First, after uniformly mixing a polymer having a particle size close to the pore size (hereinafter, referred to as a polymer for forming pores), a monomer composition used for preparing the resin base material particles, and a polymerization initiator, By carrying out the polymerization reaction, fine particles in which the polymer for forming pores are dispersed are obtained. Next, the obtained fine particles are immersed in a solvent in which the polymer for forming pores is dissolved but the polymer obtained from the monomer composition is not dissolved.

By using such a method, the surface layer of the resin base particles can be formed in a sponge shape having a fine cavity. That is, resin base particles having an opening in a portion close to the surface can be produced.

The thickness of the composite layer depends on the thickness of the interface composite layer 12.
And the structure of the composite layer and the constituent metals thereof are the same as those of the interface composite layer 12.

As a method for forming the composite layer inside the resin base particles, for example, the following method can be used. That is, the surface layer of the resin base particles is formed in advance into a sponge shape having fine cavities by the method described above,
A method can be used in which the resin base particles are immersed in a palladium chloride solution, and then reduced with hydrochloric acid to deposit metal palladium in the above-mentioned cavity. At this time, a palladium chloride solution in which tin chloride coexists may be used instead of the above palladium chloride solution. In the cavity, the porosity is large on the surface side of the resin base material particles, and the porosity is small on the center side. Here also, the method of forming the composite layer is described using palladium as an example, but the metal that can be used for these formation methods is not limited to palladium.

The conductive fine particles of the present invention may have a composite layer formed around the resin base particles as described above, or may have a composite layer formed inside the resin base particles. Preferably, a composite layer may be formed inside the resin base particles, and a composite layer may be further formed around the composite layer. Also in this case, the formation of the composite layer can be performed using the same method as the method described above.

In the conductive fine particles of the present invention, a metal coating layer is further formed around the composite layer formed inside and / or around the resin base particles. The metal coating layer may be formed around the composite layer formed inside the resin base particles, or may be formed around the interface composite layer formed around the resin base particles. However, even if it is formed around the composite layer formed inside and around the resin base particles, there is no difference in the structure, constituent material, forming method and the like. Therefore, the metal coating layer will be described below by taking a metal coating layer formed around an interface composite layer formed around resin base particles as an example.

The thickness of the metal coating layer 13 is not particularly limited, but is preferably 0.05 to 100 μm, and 0.1 to 5 μm.
0 μm is more preferred. The thickness of the metal coating layer 13 is 0.0
If the thickness is less than 5 μm, the resistance value of the conductive fine particles may increase, and sufficient conductivity may not be obtained. On the other hand, even if the thickness of the metal coating layer 13 exceeds 100 μm, the resistance value of the conductive fine particles hardly changes, which is disadvantageous in cost.

The structure of the metal coating layer 13 may be a single-layer structure or a multi-layer structure of two or more layers. In the case where the metal coating layer has a multilayer structure composed of two layers as shown in FIG. 1B, the outer metal coating layer 13b is formed of a metal coating layer made of a low melting point metal from the viewpoint of fusion to a substrate or the like. It is preferred that Also in the case of a multilayer structure having three or more metal coating layers, the outermost layer is preferably a metal coating layer made of a low melting point metal. The low-melting-point metal means a metal having a lower melting point than the metal constituting the inner metal coating layer.

The metal used for forming the metal coating layer 13 is, for example, a group IB or VII in the periodic table.
Examples include metals belonging to Group I, Group IIB, Group IIIB, Group IVB, Group VB, and the like. Among them, group IB includes copper, silver and gold, group VIII includes nickel, palladium and platinum, group IIB includes zinc, group IIIB includes gallium, aluminum, indium, and IV.
As group B, tin and lead are preferable, and as group VB, bismuth is preferable. These metals may be used alone or as two or more alloys.

The method for forming the metal coating layer 13 is not particularly limited, and a conventionally known method can be used.
Specifically, for example, electroless plating, electrolytic plating,
Examples thereof include a vacuum evaporation method and a physical evaporation method using sputtering.

Hereinafter, nickel-gold plating which is an example of a metal coating layer formed by using such a method will be described. In the above-described nickel-gold plating, after electroless nickel plating is performed on the surface of the resin substrate particles on which the interface composite layer is formed, a gold plating layer is formed on the surface by displacement plating. The electroless nickel plating includes a catalyst application step and a nickel reduction plating step.

In the catalyst application step, a catalyst serving as a nucleus for plating is deposited or adsorbed on the surface of the resin substrate particles on which the interface composite layer is formed. In this case, a platinum group metal compound may be used. preferable. Specifically, after immersing the resin base material particles having the interface composite layer in a hydrochloric acid solution of stannous chloride, the resin substrate is further immersed in a hydrochloric acid solution of palladium chloride, heated and washed. In the particles thus obtained, palladium is precipitated as ultrafine particles having a particle diameter of 50 nm or less in the interface composite layer and on the surface of the interface composite layer.

Alternatively, the resin base particles having the interfacial composite layer may be immersed in a mixed solution of tin chloride and palladium chloride, and then tin may be eluted and removed using an aqueous hydrochloric acid or sulfuric acid solution. Also in this case, similarly to the above, ultrafine particles of palladium are precipitated in the interface composite layer and on the surface of the interface composite layer.

Further, resin base particles having an interface composite layer may be immersed in a mixed aqueous solution of ascorbic acid and palladium chloride, a water-soluble monomer such as polyvinylpyrrolidone, polyacrylamide and polyvinylpyridine, and the like (Japanese Patent Laid-Open No. 61-166977). Also in this case, similarly to the above, ultrafine particles of palladium are precipitated in the interface composite layer and on the surface of the interface composite layer.

The above-described catalyst application step can be performed by the above-described method. However, when nickel-gold plating is performed on the resin substrate particles on which the interface composite layer is formed, the above-described catalyst application step is omitted. Is also good. This is because the metal constituting the interface composite layer can serve as a catalyst.

Next, nickel reduction plating is performed using the resin base particles having the interface composite layer provided with the catalyst by the above method. As a method for performing the nickel reduction plating, a conventionally known method ("Latest electroless plating technology") is used.
Published by Sogo Gijutsu Center, 1986, p. 43), and either acidic plating or alkaline plating can be used. When the acidic plating is used as the nickel reduction plating, the catalyst-treated particles are immersed in a nickel chloride or nickel sulfate solution, and the pH is reduced.
By performing nickel reduction while dripping the sodium hypophosphite solution under the conditions of 4 to 6, a nickel plating layer can be formed on the particle surface.

When alkaline plating is used, a nickel plating layer can be formed on the particle surface by performing nickel reduction while dropping a boric acid or borax solution under conditions of pH 8 to 10. . The nickel reduction reaction in the nickel reduction plating proceeds on the interface composite layer and the ultrafine particles of palladium present on the surface of the interface composite layer, thereby forming a nickel plating layer.

Next, a gold plating layer is formed on the particles having the nickel plating layer formed thereon by displacement plating. The gold plating is performed by partially eluting nickel and simultaneously depositing gold on the surface of the nickel plating layer.
Specifically, the method is carried out by charging the particles having the nickel plating layer formed therein into a solution comprising potassium cyanide alloy, EDTA and ammonium chloride, and heating the solution.

The conductive fine particles 10 having such a configuration
In this case, since the metal coating layer 13 is formed so as to bite into the interface composite layer 12, the adhesion between the resin base particles and the metal coating layer is extremely good, and the two are not easily separated. In addition, a composite layer is formed inside the resin base particles, and further, conductive fine particles having a metal coating layer formed therearound, and a composite layer is formed inside and around the resin base particles, and further around the periphery thereof. Similarly, the conductive fine particles on which the metal coating layer is formed are also formed in a state in which the metal coating layer is cut into the composite layer, so that the adhesion between the resin base particles and the metal coating layer is extremely good. Is not easily peeled off. Therefore, a highly reliable conductive connection structure can be manufactured by using the conductive fine particles of the present invention.

The above-mentioned conductive connection structure may be obtained by fixing conductive fine particles to an electrode portion of a substrate or an electronic component element, or by connecting an electrode portion of a substrate or an electronic component element to an electrode portion of another substrate or an electronic component element. Are formed by using conductive fine particles to connect between them.

As the substrate used for the conductive connection structure, for example, paper phenol resin, glass epoxy resin,
Examples include a printed wiring board based on a glass polyimide resin or the like, a flexible printed wiring board made of polyimide, a saturated polyester resin, or the like, a ceramic substrate, and the like. The structure of the substrate may be a single-layer structure or a multi-layer structure.

The substrate is provided with wiring made of a material such as gold, silver, copper, aluminum, and carbon.
An electrode portion is formed at a specific position of this wiring. The electrode portion is formed at a position corresponding to an electrode portion of an electronic component element or another substrate connected thereto.

Further, the conductive fine particles of the present invention may be fixed to the electrode portion. In order to fix the conductive fine particles to the electrode portion, using a ball mounter or a particle disperser, the conductive fine particles are placed or sprayed on the electrode portion, and then the metal coating layer of the conductive fine particles and the electrode portion of the substrate are used. And a method in which a low-melting metal such as solder is melted and joined, a soft metal such as gold, silver, and indium is pressed and joined, or a resin paste, a conductive paste, or the like is used for fixing. .

Examples of the electronic component element used for the conductive connection structure include a semiconductor element, a resistance element, a capacitor element, a thin film memory element, a crystal oscillator, and the like. Specific examples of the semiconductor element include a diode, a transistor, an IC, an LSI, an SCR, a photoelectric element, a solar cell, an LED, and the like. Further, the above IC
Specific examples of bare chip, package type I
C, a chip size package (CSP), and the like.

The electrodes of the electronic circuit element in the conductive connection structure of the present invention can be manufactured by a vapor deposition method, a sputtering method, or the like. Examples of the material of the electrodes of the electronic circuit element include aluminum, copper, nickel chrome-gold (or copper), chromium-gold, nickel chromium-palladium-gold, nickel chromium-copper-palladium-gold, molybdenum-gold, Combinations of titanium-palladium-gold, titanium-platinum-gold and the like can be mentioned. Examples of the arrangement of the electrodes of the electronic circuit element include a peripheral type, an area type, and a mixed type thereof.

Further, the conductive fine particles of the present invention may be fixed to the electrode part of the electronic component element. As a method of fixing the conductive fine particles to the electrode portion, a method similar to the method of fixing the conductive fine particles to the electrode portion on the substrate can be used.

As a method for manufacturing the conductive connection structure having such a configuration, for example, the following method can be used. That is, after the conductive fine particles are fixed to the electrode portion of the substrate or the electronic component element by the above-mentioned method, the conductive fine particles can be manufactured by connecting the conductive fine particles to the electrode portion of another substrate or the electronic component element. . At the time of connection, cream solder, resin paste, conductive paste, or the like may be used as an auxiliary.

Further, after the conductive fine particles are placed or sprayed on at least the substrate or the electrode portion of the electronic component element using a ball mounter or a particle disperser, the other substrate or the electronic component element is connected to the other electrode section. At opposite positions,
Overlap. Then, using a bonding machine, by applying heat and / or pressure, to melt the low melting point metal forming the metal coating layer of the conductive fine particles,
It can be produced by pressing a soft metal such as gold, silver or indium. When connecting,
A cream solder, a resin paste, a conductive paste, or the like may be used as an auxiliary.

Further, after dispersing the conductive fine particles in a resin binder solution, the film is cast by casting, and the film is placed on a substrate or an electronic component, and then the other substrate or the electronic component is mounted. Are placed at positions where the electrode portions face each other, and are superposed. In addition, instead of the above film, conductive fine particles are mixed with a liquid resin binder,
A conductive paste may be prepared by dispersing the paste, and the paste may be used by applying it to the substrate or the electrode side surface of the electronic component element. next,
In this state, a conductive connection structure can be manufactured by applying heat and / or pressure using a bonding machine. In general, a conductive protrusion called a bump is formed in advance on one of the electrodes of the substrate or the electronic component element, but such a bump may be omitted.

As a package system of these conductive connection structures, a flip chip shown in a sectional view in FIG. 2 and a ball grid array shown in a sectional view in FIG. 3 are preferably used. In the flip chip shown in FIG. 2, an electrode portion 24a provided on a semiconductor element 22 and an electrode portion 24b provided on a substrate 23 are connected via conductive fine particles 21,
The gap between the semiconductor element 22 and the substrate 23 is filled with an underfill material 25 as a resin binder.

In the ball grid array shown in FIG. 3, a semiconductor element 32 is connected to one surface of a substrate 33 by a package method such as the above-mentioned flip chip.
Is covered with a sealing resin 36, and the other surface of the substrate 33 is provided with an electrode portion 34 to which the conductive fine particles 31 are fixed. Note that the conductive fine particles 31 are connected to an electrode portion of another substrate or the like, but are not illustrated here.

The conductive fine particles used in the conductive connection structure may have a particle diameter of 1 in the case of the flip chip.
In the case of the ball grid array, those having a particle diameter of 50 to 700 μm are preferable.

In the conductive connection structure, one or a plurality of the conductive fine particles are arranged for each electrode portion. Usually, the gap between the electronic component element and the substrate is filled with an underfill material as a resin binder. However, there is no particular problem even if the use of the underfill material is omitted.

The conductive connection structure thus obtained is manufactured using conductive fine particles having a metal coating layer which does not generate cracks or wrinkles and does not peel off or detach from the resin base material particles. Therefore, its reliability is high. The above-described conductive connection structure is also one aspect of the present invention.

[0059]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Embodiment 1Preparation of resin base particles  10 g of polystyrene having a weight average molecular weight of 11,000 and excess
2 g of benzoyl oxide was added to 70 g of divinylbenzene and
After adding to 30 g of Tylene monomer, the mixture is stirred.
As a result, a uniform monomer solution was prepared. Next, polyvinyl
The above monomer solution is added to 800 g of a 3% solution of alcohol.
In addition, gently agitate to reduce the center particle diameter of the monomer droplet.
Was adjusted to about 50 μm. That
Thereafter, the temperature was raised to 80 ° C. while stirring, and the reaction was carried out for 15 hours.
To obtain fine particles. The obtained fine particles are
After washing, it was classified. As a result, the average particle diameter was 50 μm.
m, having a substantially normal particle size distribution with a standard deviation of 0.7 μm
Fine particles were obtained. The fine particles obtained by the above operation are
The following operation was performed as material particles.

[0061]Preparation of resin base particles having composite layer  After boiling the above resin base particles with hot toluene, ethanol
And dried. After drying, the base particles
Fine pores are formed in the surface layer after polystyrene elutes.
Had been formed. After drying is completed, 5 g of the resin base particles are sulfurized.
Immersed in an acidic aqueous solution composed of 0.02% of palladium acid,
Heated at 70 ° C. As a result, the surface of the resin base particles
Palladium was deposited in the layer.

[0062]Applying plating catalyst  5 g of the resin base particles on which the composite layer is formed are mixed with tin and para.
Catalyst solution consisting of double salt of dium (catalyst manufactured by Okuno Chemical Co., Ltd.
List C solution) 10 ml, 37% hydrochloric acid 10 ml and methano
And then filtered. After filtration is complete,
Wash the residue on paper with 5% sulfuric acid and then with water.
Fine particles to which a plating catalyst was added were obtained.

[0063]Nickel reduction plating  Nickel sulfate 17g / 100ml and sodium pyrophosphate
Plating with a composition of 34g / 100ml
Adjust the solution and add the fine particles with the plating catalyst
And then stirred at 70 ° C. for 60 minutes while stirring
While dropping 17g / 100ml of sodium acid, nickel
The surface was nickel-plated by plating
Fine particles were obtained. Nickel plating layer thickness is 0.15μm
Met.

[0064]Nickel and eutectic solder by electroplating
Layer formation  Next, the obtained fine particles 10 whose surface is nickel-plated
g, and use an electroplating apparatus 40 shown in a sectional view in FIG.
Then, a thick film nickel plating was performed on the surface. Electric mail
The locking device 40 is fixed to the upper end of the vertical drive shaft 50.
A disk-shaped bottom plate 47 and an outer peripheral upper surface of the bottom plate 47,
An annular porous body 49 through which only the plating solution passes, and a porous body 4
9, a contact ring 48 for energization arranged on the upper surface, and an annular shape
Is opened at the center where the lower outer peripheral portion is arranged on the contact ring 48.
A substantially conical hollow cover 41 having a portion 46;
A porous body 49 is provided between the lower peripheral portion of the bar 41 and the bottom plate 47.
And a contact ring 48 to be held.
And inserted through the opening 46 of the plating tank 51.
Through the electrode 42 that contacts the plating solution and the opening 46.
A supply pipe 44 for supplying the plating solution to the plating tank 51;
A container 43 for receiving the plating solution scattered from the holes of the body 49;
A discharge pipe 45 for discharging the plating solution stored in the container 43;
Have.

In the electroplating apparatus 40, fine particles are put into a plating tank 51, and a plating solution is supplied from the supply pipe 44 into the plating tank 51. Since the plating solution flows out of the plating tank 51 through the porous body 49 with the rotation of the drive shaft 50, the reduced amount is supplied from the supply pipe 44.

The fine particles are energized and plated while being pressed against the contact ring 48 by the action of centrifugal force due to the rotation of the plating tank 51. Since the rotation is also decelerated and stopped simultaneously with the stop of energization, the fine particles are dragged by the flow due to gravity and the inertia of the plating solution and move toward the center of the bottom plate 47. While being mixed with the plating solution, it is pressed against the contact ring 48 in another posture and plated. By repeating this cycle, a plating layer having a uniform thickness is formed on all the fine particles present in the plating tank 51.

The plating conditions in this operation were as follows: the temperature of the plating solution was 50 ° C., the current was 36 A, and the current density was 0.
36 A / dm ² , voltage was set to 15 to 16 V, and current was applied between both electrodes for 20 minutes. The peripheral speed of the plating tank 51 is 250
m / min, and the rotation direction was reversed every 11 seconds. In addition,
The plating solution is a Watt bath, and has a composition of nickel concentration 42 g / l, nickel sulfate 150 g / l, boric acid 3
1 g / l. By performing this electroplating, fine particles having a nickel plating layer having a nickel film thickness of 2.0 μm were obtained.

Next, the obtained nickel-plated fine particles 10
g, and eutectic solder plating was performed using an electroplating apparatus 40.

The plating conditions in this operation were as follows. An alloy of tin (Sn): lead (Pb) = 6: 4 was used for the electrode 42, and an acidic bath (537 manufactured by Ishihara Chemical Co., Ltd.) was used as a plating solution.
A) was used. The temperature of the plating solution was 20 ° C., the current was 24.8 A, and the current density was 0.5 A / dm ² . The plating solution had a total metal concentration of 21.39 g /
1, containing 65.3% of metal ratio Sn% in the bath, 106.4 g / l of alkanolsulfonic acid, and 40 mL of additive.

After plating was completed, conductive fine particles having a solder coating were obtained. When the solder coating of the conductive fine particles was analyzed by an atomic absorption method, Sn was 61.5%,
Melting point was 186 ° C. The resistance under the condition where 5% compression strain was applied to the fine particles was 0.02Ω.
And showed good conductivity.

[0071]Adhesion of metal coating layer to resin substrate particle surface
Evaluation  The obtained conductive fine particles were placed in two pieces of glass having a thickness of 1.1 mm.
60 pieces per square mm between
The end of the glass plate was sealed with tape. Next, the gala
50 times of rubber roller with a load of 5 kg applied to the surface of the plate
Ironing was given by reciprocating. After ironing,
Observation of conductive fine particles with a magnifying glass of 50x magnification
Of course, the metal coating layer of conductive fine particles is not damaged at all.
And no peeling was observed.
It had adhesive properties.

Comparative Example 1 Resin base particles were prepared in the same manner as in Example 1 except that 10 g of polystyrene having a weight average molecular weight of 11,000 was not used. The obtained resin base particles had an average particle size of 50 μm and a standard deviation of 0.60 μm, and had a particle size distribution almost close to a normal distribution. Next, using the resin base particles, the same plating catalyst as in Example 1 was applied, nickel reduction plating was performed, and further, nickel and a eutectic solder layer were formed by electroplating to obtain a conductive property. Fine particles were obtained. With respect to the obtained conductive fine particles, the adhesion of the metal coating layer to the resin base material particle surface was evaluated in the same manner as in Example 1, and peeling of the metal coating layer was observed.

Embodiment 2Preparation of resin base particles  In the same manner as in Comparative Example 1, the average particle diameter is 20 μm, and the standard deviation is
0.60 μm resin base particles were produced.Formation of interfacial composite layer  Solid epoxy (Epicoat 100 made of oiled shell epoxy)
1) 2 g was added and dissolved in 40 ml of acetone,
6 ml of water, 5 g of the base particles and 2-E as a curing agent
Cyl-4-methylimidazole (manufactured by Shikoku Chemicals,
0.4 g of azole 2E4MZ) and mix well
After that, the acetone was evaporated while stirring. After evaporation
The dried product was crushed and the lumps were loosened. These particles are
70 ° C suspended in 1.5% aqueous alcohol solution
Epoxy that is heated and coated around the resin base particles
The resin layer was cured. Further, 5 g of the particles were added to palladium sulfate.
Immersed in an acidic aqueous solution consisting of 0.02%
Heated at ° C. As a result, the epoxy coating layer
Ultra-fine particles of radium are precipitated, forming an interfacial composite layer
It had been.

[0074]Applying plating catalyst  Using the resin substrate particles on which the obtained interface composite layer was formed
Except for the above, the plating catalyst was applied in the same manner as in Example 1.
Thus, fine particles provided with a plating catalyst were obtained.

[0075]Nickel reduction plating  Except using the obtained fine particles to which the plating catalyst was applied.
Performs nickel reduction plating in the same manner as in Example 1,
Fine particles having a nickel-plated surface were obtained.

[0076]Gold displacement plating  The resulting nickel-plated particles are suspended in water
And with stirring, gold consisting of potassium gold cyanide 5%
By heating to 70 ° C while dropping the displacement plating solution
A metal replacement reaction was performed to obtain conductive fine particles. In addition,
The progress of the conversion reaction is when the particles change from black gray to gold
Confirmed by After completion of the gold substitution reaction, the resulting conductive fine
When the cross section of the particles was observed with an electron microscope, the thickness was 0.1
5μm nickel plating layer and 0.06μm thick gold plating
A stick layer was formed. In addition, 5% compression
It was 0.06Ω when the resistance was measured under the strained condition.
And showed good conductivity.

[0077]Adhesion of metal coating layer to resin substrate particle surface
Evaluation  About the obtained conductive fine particles, it carried out similarly to Example 1.
Evaluation of adhesion of metal coating layer to resin substrate particle surface
However, the metal coating layer of conductive fine particles is not damaged at all.
No peeling was observed, strong against resin base particles
Had good adhesion.

Comparative Example 2 Conductive fine particles were produced in the same manner as in Example 2 except that the formation of the interface composite layer was not performed. With respect to the obtained conductive fine particles, the adhesion of the metal coating layer to the resin base material particle surface was evaluated in the same manner as in Example 1, and peeling of the metal coating layer was observed.

[0079]

Since the conductive fine particles of the present invention have the above-mentioned structure, they do not have cracks or wrinkles and have a metal coating layer which does not peel off or detach from the resin base particles. Further, the conductive connection structure of the present invention is manufactured using the conductive fine particles, and has high connection reliability.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views showing one embodiment of the conductive fine particles of the present invention.

FIG. 2 is a cross-sectional view showing an example of the conductive connection structure of the present invention.

FIG. 3 is a cross-sectional view showing an example of the conductive connection structure of the present invention.

FIG. 4 is a sectional view showing an electroplating apparatus used in an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 conductive fine particles 11 resin base particles 12 interface composite layer 13, 13 a, 13 b metal coating layer 21 conductive fine particles 22 semiconductor element 23 substrate 31 conductive fine particles 32 semiconductor element 33 substrate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K022 AA26 AA35 AA41 BA01 BA02 BA03 BA08 BA10 BA14 BA17 BA18 BA21 BA28 DA01 5E319 AA03 AB05 BB04 BB16 BB20 GG11 5G307 AA02 HA02 HB06 HC01

Claims (4)

[Claims] 1. A conductive layer, wherein a composite layer comprising a metal and a resin is formed inside and / or around resin base particles, and a metal coating layer is further formed around the composite layer. Fine particles. 2. The conductive fine particles according to claim 1, wherein the metal concentration in the composite layer increases from the inside to the outside of the composite layer. 3. The conductive fine particles according to claim 1, wherein the metal constituting the composite layer is palladium. 4. A conductive connection structure produced using the conductive fine particles according to claim 1, 2 or 3.