JPH08249922A - Coated particle - Google Patents

Abstract

PURPOSE: To provide high and durable connection reliability and make a fine circuit connection possible by practically coating particles, which consist of a polymer core material having a conductive metal thin film layer on the surface, with a thermoplastic insulating layer. CONSTITUTION: A coated particle is produced by forming an insulating layer 3 on the surface of a conductive particle, which is produced by forming a conductive thin film 2 on the surface of a polymer core material 1. Or, a coated particle is produced by forming a hard and conductive material with smaller diameter than that of a polymer core material on the surface of a particle, which is produced by forming a conductive metal thin film on the surface of the core material of a polymer, and further forming a thermoplastic insulating layer on the surface of the conductive material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting member for a fine circuit, and more specifically to a connecting terminal of an integrated circuit, a liquid crystal panel or the like, and a connecting terminal electrically or mechanically on a circuit board arranged opposite to the connecting terminal. The present invention relates to a coated particle suitable for a connecting member for connecting.

[0002]

2. Description of the Related Art As electronic parts have become smaller and thinner, circuits used therein have become higher in density and higher in definition. Since it is difficult to connect these fine circuits with conventional solder and rubber connectors, anisotropic conductive adhesives and film-like materials (hereinafter referred to as connecting members) have come to be frequently used. It was According to this method, a connecting member layer made of an adhesive containing a predetermined amount of a conductive material is provided between opposing circuits, and pressing or heating / pressurizing means is provided, so that the circuits are adjacent to each other at the same time as electrical connection. Insulation is provided between the circuits, and the circuits facing each other are fixed by adhesion. However, in this method, conduction between circuits is mainly formed by a plurality of conductive materials, in many cases fibrous materials such as carbon, metal particles such as Ni or glass, etc. as a core, and a conductive layer is formed on the surface layer. It is obtained by contact with a conductive material composed of particles and the like, and since these materials are rigid,
The contact area between the circuits or between particles / particles was not sufficient, and the connection reliability was insufficient. As an attempt to increase the contact area, there is a method of using low melting point metal particles such as solder as a conductive material, but if the temperature is higher than the melting point of the metal, the adjacent circuits will communicate with each other as in the case of conventional soldering. Since the melting point does not occur and the metal does not melt below the melting point, a sufficient contact area cannot be obtained. Therefore, it is necessary to strictly control the temperature-pressure-time during circuit connection within a narrow width near the melting point, but it was not practical because the thermal conductivity differs depending on the circuit board. Further, the disadvantage common to the conductive materials as described above is that the coefficient of thermal expansion is generally smaller than that of the adhesive by about one digit, so that it is smaller than the expansion amount of the conductive material at a high temperature, for example, in the connection circuit. The change in the gap between the two (following ability to the temperature change)
Since the contact area and the number of contact points of the conductive material to the circuit are reduced, the connection resistance increases and conductive failure occurs.Even if the initial connectivity is obtained, long-term reliability including temperature change including Was inferior to As a method of resolving the drawbacks of the above-mentioned conventional conductive material and significantly improving the reliability, we have developed a method in which the surface of the polymer core is substantially covered with a thin metal layer (hereinafter referred to as conductive material). A method of using a hydrophilic particle was proposed (Japanese Patent Application No. 61-31088). According to this method, the conductive particles are appropriately deformed so as to be pressed between the circuit surfaces or the conductive particles by pressure or heat and pressure at the time of circuit connection,
Since a sufficient contact area can be obtained and the polymer core material has thermal softening properties, rigidity and thermal expansion / contraction properties very close to the properties of the adhesive, the range of conditions for connection is wide, and the connection part is resistant to temperature changes. Since it has followability, the long-term reliability of the connection part is significantly improved.

[0003]

The above-described circuit connecting member is extremely useful because it is a collective connecting material for a large number of circuits, but it has a high resolution for connecting fine circuits which are becoming higher in definition. There is an extremely strong demand for both improvement and long-term connection reliability as described above. That is, in the prior art, a circuit of 5 lines / mm (circuit width 100
connection is possible, but with recent miniaturization of circuits, for example, 10 lines / mm (circuit width 50
For circuit connection (μm, insulation width 50 μm) and IC chip bonding applications, circuit miniaturization is progressing further, for example, the connection area of one electrode is 50 μm □. The basic idea for increasing the resolution of connecting members is to make the particle size of the conductive material smaller than the insulating part between circuits to ensure insulation with adjacent circuits, and to the extent that the conductive material does not contact. The purpose is to reliably obtain conductivity in the circuit connecting portion while adjusting the addition amount. However, if the particle size of the conductive material is reduced, the particles will be secondary aggregated due to the increase of the surface area and the number of particles remarkably, and the insulation between the adjacent circuits cannot be maintained. Since the number of conductive materials on the power circuit decreases, the number of contact points becomes insufficient, and conduction between the connection circuits cannot be obtained.Therefore, it is extremely difficult to achieve high resolution of connection members while maintaining long-term connection reliability. It was

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above drawbacks, and an object of the present invention is to provide a high-resolution circuit which has excellent long-term connection reliability and enables connection of fine circuits. The purpose of the present invention is to provide a coated particle suitable for a connecting member. That is, the present invention relates to coated particles in which a polymer is used as a core material and a thin conductive metal layer is formed on the surface of the polymer to be substantially covered with a thermoplastic insulating layer. Further, using a polymer as a core material, a conductive material having a smaller particle size than the polymer core material and a hard conductive material is formed on the surface of the particles formed by forming a conductive metal thin layer on the surface of the conductive material. The present invention relates to coated particles whose surface is substantially covered with a thermoplastic insulating layer.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The coated particles of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of coated particles in which an insulating layer 3 is formed on the surface of conductive particles according to the present invention in which a conductive thin layer 2 is formed on the surface of a polymer core material 1. In this case, as the material of the polymer core material 1, various rubbers such as styrene butadiene rubber and silicone rubber, various plastics such as polystyrene and epoxy resin, and various polymer substances such as natural products such as starch and cellulose are used. Applicable. The shape is preferably substantially spherical, but is not particularly limited. Further, it may be a complete packing, a foam having bubbles inside, a hollow body having a gas inside, or an agglomerate that is a collection of small particles, and these may be used alone or in combination.

The material of the electroconductive thin layer 2 may be various electroconductive metals, metal oxides, alloys, electroconductive polymers such as polyacetylene series, such as Zn, Al, Sb,
Au, Ag, Sn, Fe, Ta, Cu, Pb, Ni, P
d, Pt, etc., which can be used alone or in combination, and for special purposes such as improvement of hardness, surface tension and adhesion, Mo, Mn, C, etc.
Other elements and compounds such as d, Si, and Cr can also be added. Further, the conductive thin layer 2 may have a multi-layer structure including a plurality of layers. As a method for forming the conductive thin layer 2 on the polymer core 1, a so-called dry method such as a vapor deposition method, a sputtering method, an ion plating method, and a thermal spraying method, a plating method, or the like can be applied. The electroless plating method that facilitates obtaining a thin layer having a uniform thickness is particularly preferable due to the above dispersion system. The thickness of the conductive thin layer 2 is 0.01 to 5 μm.
The degree is generally applicable. The thickness here is, for example, 0.01 μm when including a base layer, if any.
If the thickness is less than 5 μm, the conductivity will be insufficient, and if the thickness is 5 μm or more, the followability to the temperature change of the polymer core material will be suppressed, and the connection reliability will be unsatisfactory.

FIG. 2 is an example of an application example of the coated particles. A conductive material 4 is adhered and formed on the surface of the conductive particles in which the conductive thin layer 2 is formed on the surface of the polymer core material 1. FIG. 3 is a schematic cross-sectional view of coated particles forming the insulating layer 3. In this case, the conductive material 4 is required to have higher rigidity than the polymer core material 1 and the insulating layer 3 at the time of circuit connection and exhibit no deformability, and have a particle size smaller than that of the polymer core material 1. The particle size is preferably 0.01 to 30 μm. Examples of the conductive material 4 in this case include various kinds of metals similar to those of the conductive thin layer 2 described above, ceramics, glass,
It may be formed on the surface of a material such as carbon which is not easily deformed. As a method for depositing and forming the conductive material 4 on the polymer core material 1, for example, there is a method in which the conductive material 4 is adsorbed by being sprayed at a high temperature, or is adhered by a thin layer of an adhesive. According to the coated particles of FIG. 2, since the conductive material 4 has high rigidity and does not exhibit deformability at the time of connection, the oxide layer and the contamination layer on the circuit surface can be pierced and connected, so that low resistance initial connection characteristics can be obtained. Further, since the particle diameter of the conductive material 4 is made smaller than that of the polymer core material 1, since the conductive material 4 can follow the thermal expansion between the connecting circuits, the connection reliability becomes good. Therefore, it can be widely applied to various circuit surfaces.

FIG. 3 shows the case where the conductive particles 5 form an aggregate which is a collection of small particles, and the insulating layer 3 is formed on the surface thereof. In this case, the coated particles can be easily obtained by using the small-sized particles in which the conductive particles 5 easily aggregate. FIG. 4 shows a case where the coated particles having the insulating layer 3 formed on the surface of the conductive particles 5 form an aggregate. Since the surface of each single particle is insulated, it is easy to obtain a connection member with high resolution. Any of these can be preferably applied, and can be mixed with a single particle.

The conductive particles in the description of FIGS. 1 to 4 are applicable to various particle sizes in principle because the surface of the conductive particles is covered with an insulating layer. It is necessary to be less than (space) from the viewpoint of ensuring reliability of resolution. For example, 10 lines / mm (circuit width 50
In order to achieve a resolution of (μm, insulation width of 50 μm), it is necessary that the particle size does not exceed 50 μm. In this case, if particles having a particle size of 50 μm or more are present in the space portion, the insulating layer in the circuit portion is destroyed by heating and pressurizing at the time of circuit connection, so that the insulating property from the adjacent circuit cannot be maintained. As the insulating layer 3 in FIGS. 1 to 4, an insulator having fluidity by heating and pressing can be applied. That is, the conductive particles and the circuit or the insulating layer 3 between the conductive particles flow between the circuits to be connected by the heating and pressurization at the time of circuit connection and are removed from the contact portion, so that the conductivity is obtained between the connecting circuits. To be Typical of these insulating layers 3 are thermoplastic resins and hot-melt adhesives. Also useful are base polymers and elastomers of hot melt adhesives having thermal softening properties and melting points, such as polyethylene, ethylene copolymer polymers, ethylene-vinyl acetate copolymers, polypropylene, ethylene-acrylic acid copolymers,
Ethylene-acrylic acid ester copolymer, polyamide,
Polyester, styrene-isoprene copolymer, styrene-divinylbenzene copolymer, ethylene-propylene copolymer, acrylate ester rubber, polyvinyl acetal, acrylonitrile-butadiene copolymer, styrene, phenoxy, solid epoxy, polyurethane, etc. is there. In addition, there are natural and rigid resins such as terpene resin and rosin, and chelating agents such as EDTA, and these can be used alone or in combination.

The conditions under which the insulating layer 3 exhibits fluidity by heating and pressurizing are 80 to 2 which are conditions at the time of circuit connection.
50 ° C, and 0.1-100 kg / cm ² Can be applied. If the temperature is 80 ° C. or lower, the heat resistance of the circuit connecting portion is deteriorated, which is not preferable. The pressure is 0.1 kg / cm ^2. In the following, sufficient conductivity cannot be obtained because the insulating layer at the contact point with the circuit is not sufficiently removed, and 100 kg / cm ² The above is not preferable because it causes mechanical damage to the connecting parts and the like. As a method for forming these insulating layers 3 on the conductive particles, there are an electrostatic coating method, a fine particle adsorption method, a hot melt coating method, a solution coating method and the like. Among the above, when the insulating layer 3 is soluble in a general-purpose solvent, the solution coating method in which the insulating layer forming material is in the form of a solution and the solvent is removed after treating the conductive particles can be carried out with simple equipment. Is preferred. Further, the insulating layer may be crosslinked to improve solvent resistance and heat resistance. The thickness of the coating layer is preferably about 0.1 to 5 μm. If the thickness is 0.1 μm or less, the insulating property is insufficient, and if the thickness is 5 μm or more, it is difficult to sufficiently remove the insulating layer at the time of circuit connection, and thus it is difficult to obtain sufficient conductivity. A connecting member can be manufactured by mixing the above-described coated particles in an adhesive.

The amount of the coated particles occupying in the adhesive can be filled with high density because the surface is covered with the insulating layer. That is, in the conventional connecting member of the circuit, the addition amount thereof is generally 5% by volume or less to control the insulating property with the adjacent circuit, but in the present invention, it is as large as 2 to 35% by volume. Can be added to. The composition for a connecting member in which the above-mentioned coated particles are mixed, constitutes a connecting member directly on a circuit using a means such as screen printing or a roll coater on one or the other side of the circuit that requires connection, or in the form of a film. It may be a connecting member. As a method of using the connecting member using the coated particles according to the present invention, for example, in the case where a film-like connecting member is temporarily attached to a circuit, a separator is peeled off, or the above composition is applied onto the circuit. Then, in a state where the solvent and the dispersion medium are removed as necessary, other circuits to be connected may be aligned with the surface and heated and pressed by a hot press, a heating roll or the like.

When the adhesive softens and flows due to heating and pressurizing at the time of circuit connection, the insulating layer also softens and is removed from the pressing portion. In other words, in the circuit parts that face each other, the circuit generally has a constant height as compared with the insulating part, and because the hardness is higher than the insulating part, it is less deformable, so it has priority over the insulating part. Since the conductive particles 1 are electrically pressed, the conductive layer 1 has no insulating layer on the circuit surface, which is the pressing direction, and conductivity is obtained. Therefore, the insulating layer 3 is eliminated between the circuits of the connecting portion, and the insulating layer 3 can be held between the insulating portions. At this time, the conductive particles are softened and deformed along the circuit to increase the contact area. Further, the polymer core material 1 can be approximated to the coefficient of thermal expansion of the adhesive, and the conductive thin layer 2
Since it is extremely thin, the polymer core material 1 can also be thermally expanded even when the circuits are thermally expanded. Therefore, the polymer core material 1 has a good followability with respect to the temperature change of the connection part and is excellent in long-term reliability. You can get a good connection.

The operation of the coated particles according to the present invention will be described. In the coated particles according to the present invention, the insulating layer is softer than the polymer as the core material at least under heating and pressure. Therefore, the insulating layer on the surface of the conductive particles is softened and fluidized by heating and pressurizing at the time of circuit connection, and the coating is removed at the circuit or the contact portion of the particles to give conductivity between the connection circuits. On the other hand, in the insulating circuit portion, since the pressure is not so high as the particles between the circuits, the insulating layer coating is maintained as it is, so that the insulating property is obtained. Because of the above reasons
The coated particles can be filled in the adhesive at a high concentration, and since the conductive particles are surely present even in a minute connection area, conduction can be surely obtained, so that a high-resolution connection component can be obtained. In addition, the conductive particles inside the coated particles are softened and deformed by heating and pressurizing at the time of circuit connection to improve the contact area with the circuit and particles, and have the following property with respect to the temperature change of the connection part. It is possible to remarkably improve the reliability of the above, especially the long-term connection reliability such as when including the high temperature and high humidity test and the temperature change. Further, since the conductive particles are covered with the insulating layer, it is possible to prevent the particles from being oxidized and deteriorated, so that it is possible to obtain a connecting member having excellent conductivity and particularly stable characteristics.

[0014]

EXAMPLES The present invention will be described in more detail by way of examples. Example 1 (1) Preparation of conductive particles (a) Pretreatment Conivex C type (spherical phenol resin, average particle size 20 μm, trade name of Unitika Ltd.) is forcibly stirred in methyl alcohol to degrease it. Then, pretreatment which also serves as roughening was performed, and then methyl alcohol was separated by filtration to obtain a pretreated polymer core material. (B) Activation Next, circuit prep 3316 (PdCl + HCl +
SnCl ₂ -based activation treatment solution, dispersed in Nippon Electroplating Engineers Co., Ltd.)
An activation treatment was carried out by stirring at 5 ° C. for 20 minutes, followed by washing with water and filtration to obtain a polymer core having an activated surface. (C) Electroless Ni Plating Particles after the activation treatment are treated with blue shoe (electroless Ni plating solution, bath capacity 300 μdm ² / L, Nippon Kanigen Co., Ltd.
It was immersed in a liquid (product name) and stirred at 90 ° C. for 30 minutes. After a predetermined time, it was washed with water. The amount of plating solution was calculated from the surface area of the particles. (D) Electroless Au Plating The surface of the Ni-coated particles obtained above was subjected to Au displacement plating. The plating solution is an electroless prep (electroless Au plating solution, trade name of Japan Electroplating Engineers Co., Ltd.), which is subjected to a plating treatment at 90 ° C. for 30 minutes, and then washed well with water, Then, it dried at 90 degreeC-2 hours, and obtained the electroconductive particle. The particles had a thin metal layer of Ni 0.3 μm / Au 0.05 μm. (2) Preparation of Coated Particles Coated particles having an insulating layer formed on the surface of the conductive particles were prepared. A 1% dimethylformamide (DMF) solution of paraprene P-25M (thermoplastic polyurethane resin, softening point 130 ° C., trade name of Nippon Elastollan Co., Ltd.) was used as a material for the insulating layer, and conductive particles were added and stirred. After this, spray dryer (GA-32 manufactured by Yamato Scientific Co., Ltd.)
Spray drying at 100 ° C. for 10 minutes to obtain coated particles. The average thickness of the coating layer at this time was determined by using an electron microscope (S
As a result of cross-sectional observation by EM), it was about 1 μm. (3) Preparation of Connection Member A hot melt adhesive having a lower solid content ratio was prepared as an insulating adhesive. The melt index (M
I. Compliant with ASTM D-1238, but 150 ° C) is 2
It was 0 g / min. Toughprene (styrene-butadiene-block polymer, trade name, manufactured by Asahi Kasei Co., Ltd.) ... 60 parts (weight) YS Polystar T-115 (Terpene phenol resin, trade name of Yasuhara Yushi Co., Ltd.) ... 40 parts Toluene ... ... 200 parts The above-mentioned coated particles were added and mixed in the adhesive solution consisting of the above. The amount of the coated particles added at this time was 5% by volume based on the solid content of the adhesive. This mixed solution was applied on a separator (silicone-treated polyester film thickness 38 μm) by a bar coater, and toluene was removed by drying at 100 ° C. for 20 minutes to obtain a connecting member having a thickness of 25 μm.
Since the insulating layer was insoluble in toluene and the adhesive was soluble, both were not compatible and a good connecting member was obtained. (4) Circuit connection A flexible circuit board (FPC) having a circuit width of 50 mm, a pitch of 100 μm, and a Cu circuit having a thickness of 18 μm and having a total circuit width of 50 mm, and a connecting member cut into an adhesive width of 3 mm and a length of 50 mm is mounted. Place it at 140 ° C-2
kg / cm ² FPC with connecting member by heating and pressing for -5 seconds
I got Then, the separator is peeled off, and another transparent conductive glass having the same pitch (ITO circuit, glass thickness 1.
1mm) and position of the circuit under the microscope,
℃ -30kg / cm ² The circuit was connected by applying heat and pressure for -20 seconds. (5) Evaluation method and result The connection resistance of the circuit obtained above and the insulation resistance between adjacent circuits were measured. Connection resistance is multimeter (TR-68
77, manufactured by Advantest Corporation, insulation resistance is a high ohm meter (TR-8611, manufactured by Advantetos Corporation)
I went in. The results of these measurements are shown in Table 1, and good connection resistance between circuits and insulation resistance between adjacent circuits were obtained for a high-density circuit of 10 lines / mm. In addition, the connection body has a thermal shock test (-40 ° C / 30 minutes ⇔ 100 ° C /
After 500 cycles of treatment (30 minutes for 1 cycle), the same evaluation as above was performed, but almost no deterioration was observed in both the connection resistance and the insulation resistance. Since this thermal shock test is considered to have severe long-term reliability, it is clear that this example also has excellent long-term reliability. When the cross section of the connection portion of this example was observed by SEM, the conductive particles existed as a single layer between the connection circuits and were deformed along the circuit.

Example 2 Particles were formed in the same manner as in Example 1 except that Ni powder (carbonyl method, substantially spherical particles having surface irregularities with an average particle size of 2 μm) was attached and formed on the surface of conductive particles by the following method. Was used.
In the method, conductive particles were added and stirred in a 0.5% toluene solution of a hot melt adhesive which is the adhesive material of Example 1. After that, most of the DMF was dried in a spray dryer, 10% by volume of the Ni powder was added to the spray dryer, and the powder was further dried with a spray dryer to form the Ni powder on the conductive particles. . Then, a coating layer was prepared in the same manner as in Example 1. The evaluation results of this example are shown in Table 1, and good characteristics having both good resolution and long-term reliability were obtained.

Example 3 The polymer core was the Unipex C of Example 1, but the particles were classified into particles of 5 μm on average by using a microsieve so as to have a path of 3 μm on 8 μm. After electroconductive particles were obtained by the same electroless plating as in Example 1, coated particles were obtained by the same method using the hot melt adhesive used in Example 1 as a 1% toluene solution. Adhesive is Bayronal MD
-1930 (water-dispersion type thermoplastic polyester resin, melting point 113 ° C., trade name of Toyobo Co., Ltd.) was used. The coated particles were dispersed in the same manner as in Example 1 to obtain a connecting member. Since the adhesive is a water-dispersed type, it is incompatible with the insulating layer, and the connection member could be manufactured well. At this time, the added amount of the coated particles was 25% by volume with respect to the adhesive, and the thickness of the connecting member was 15 μm. The evaluation results of this example are shown in Table 1, and good characteristics having both good resolution and long-term reliability were obtained. When the cross section was observed in the same manner as in Example 1, the particles were densely packed.

Comparative Example 1 Except that conductive particles not forming an insulating layer were used as the conductive layer,
A connecting member was prepared and evaluated in the same manner as in Example 3. The results are shown in Table 1. Although a good connection resistance value was obtained, the insulating property between adjacent circuits was lost and it could not be applied as a connection member.

Comparative Example 2 A connecting member was prepared and evaluated using coated particles having an insulating layer formed thereon in the same manner as in Example 3 except that solder particles having a melting point of 183 ° C. and an average particle diameter of 10 μm were used as the conductive material. The results are shown in Table 1.
As shown in Fig. 5, although the insulation with the adjacent circuit was obtained, the sufficient connection could not be obtained by the evaluation of long-term reliability. The reason for this is that the thermal expansion coefficient of solder particles (coefficient of linear expansion 2.8 × 10 ⁻⁵ / ° C.) and the adhesive (coefficient of linear expansion 30 × 10 ⁻⁵ / ° C.) are significantly different, so that the solder during the thermal shock test. It is considered that the particles did not follow the temperature change.

[0019]

[Table 1]

Example 4 An IC chip was connected to an FPC using the connecting member of Example 3. The IC chip used was 5 × 7 mm and had an electrode pad of 50 μm □ (height 2 μm, aluminum surface was treated with gold, the number of electrodes was 50) on one side, and the pad surface of Example 2 was used. The connecting member was placed and lightly pressure-bonded on a 150 ° C. hot plate to remove the separator. Next, the FPC (electrode height of the copper circuit is 18 μ
m, the substrate polyimide, commonly called TAB), and the IC and FPC were connected by heating and pressurizing at 160 ° C.-10 kg / cm ² -10 seconds. When this connection body was evaluated, conduction was surely obtained at each electrode and it was insulated from an adjacent circuit. Moreover, the long-term reliability similar to that of Example 1 was evaluated, but no characteristic deterioration was observed. In this embodiment, conductive particles having an average particle size of 5 μm are contained in the adhesive in an amount of 25% by volume.
Since it was added in a large amount, it was found that the electrode connection of a small area of 50 μm □ can be easily and surely made and, in addition, it has good long-term reliability.

[0021]

As described in detail above, according to the present invention, it is possible to provide coated particles suitable for a connecting member of a high resolution circuit capable of connecting a fine circuit together with long-term connection reliability. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing coated particles according to the present invention.

FIG. 2 is a schematic cross-sectional view showing coated particles according to the present invention.

FIG. 3 is a schematic cross-sectional view showing coated particles according to the present invention.

FIG. 4 is a schematic cross-sectional view showing coated particles according to the present invention.

[Explanation of symbols]

 1 Polymer Core Material 2 Conductive Thin Layer 3 Insulating Layer 4 Conductive Material 5 Conductive Particle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akashi Nakaso 1500 Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Shimodate Research Center

Claims (2)

[Claims] 1. Coated particles in which a polymer is used as a core material and a thin conductive metal layer is formed on the surface of the polymer to be substantially covered with a thermoplastic insulating layer. 2. A conductive material having a particle diameter smaller than that of the polymer core material is formed on the surface of the particles having a polymer as a core material and a thin conductive metal layer formed on the surface of the polymer. Coated particles in which the surface of the conductive material is substantially covered with a thermoplastic insulating layer.