JP2008186762A - Manufacturing method for particle-filling object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a particle-filling object capable of simply and surely filling up conductive particles in holes of a porous body. <P>SOLUTION: Upon manufacturing the particle-filling object 20, after spraying powdery conductive particles 12 on a surface of the porous body 10, the surface of the porous body 10 is rubbed through by a rubbing-through means 16 while the conductive particles 12 are attracted by magnetic force of a magnetic force generating means 14 to a porous body 10 side, and the conductive particles 12 are filled up in the holes 18 of the porous body 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a particle filler, and more particularly to a method for producing a particle filler suitable for use in an anisotropic conductive film or the like.

  In recent years, in various industrial fields, a porous material filled with a functional substance has been used for various applications.

  For example, in the fields of electrical and electronic equipment, a conductive film filled with conductive particles and an adhesive layer formed on both sides thereof is used as an anisotropic conductive film.

  This anisotropic conductive film can exhibit anisotropic conductivity as a whole by the conductivity in the film thickness direction by the conductive particles and the insulation in the film surface direction by the porous film. Therefore, it is suitably used for electrically and mechanically connecting members having conductors arranged at a narrow pitch, such as connection between a circuit pattern of a circuit board and an IC chip.

  Here, as a technique for filling conductive particles in a porous body such as a porous film, for example, in Patent Document 1, a porous film (pore diameter: 5 μm) is fixed on a glass substrate and the film surface is constant. Disposing another glass substrate at a distance, injecting an aqueous dispersion of Ag particles (average particle size 50 nm) into the gap formed between the film surface and the glass substrate, and then sliding the glass substrate. Thus, a technique for filling the Ag particle group in the hole is disclosed.

  Further, for example, in Patent Document 2, conductive particles (particle size: 6 μm) are sprayed on a core film having a large number of through holes (diameter: 8 μm), and then ultrasonic vibration is applied to the film, thereby allowing the film to enter the through holes. Techniques for filling conductive particles are disclosed.

JP 2006-233019 A JP 2003-13021 A

  However, all of the conventional particle filling techniques have the following problems.

  That is, the former particle filling technique is a wet method. Therefore, depending on the material of the porous membrane, the porous membrane may be eroded (solvent dissolution, swelling, etc.) by the solvent in which the particles are dispersed.

  In addition, the compatibility between the porous membrane and the solvent does not necessarily match the particle dispersibility of the solvent, and even a solvent with poor particle dispersibility must be used. Therefore, the slide operation has to be repeated many times in order to increase the particle filling rate.

  In the former particle filling technique, when particles that are much smaller than the pores are filled, the aggregation of the particles in the dispersion does not have to be concerned.

  However, in the case where particles having the same size as the pores are filled, it is necessary to use a dispersion in which the particles are monodispersed. In order to disperse the particles singly, the concentration of the particles had to be reduced, and it was difficult to fill the pores with the particles by a single slide operation.

  On the other hand, the latter particle filling technique is considered to have a low probability that particles actually enter the pores. Also, during continuous production, it may be difficult to ultrasonically vibrate the film on the line.

  Then, this invention is providing the manufacturing method of the particle | grain filling body which can be filled with the electroconductive particle in the hole of a porous body easily and reliably.

  In order to solve the above-mentioned problem, the method for producing a particle packing according to the present invention is to spray powdered conductive particles on the surface of a porous body and then attract the conductive particles to the porous body side by magnetic force. The gist is that the surface of the porous body is scraped off by a scraping means, and the conductive particles are filled in the pores of the porous body.

  As the porous body, a porous film having a large number of pores or a mold having a large number of pores can be suitably applied.

  Here, the porous membrane has a relative humidity of 50 and a support obtained by casting a polymer solution containing at least a hydrophobic and volatile organic solvent, a polymer soluble in the organic solvent, and a surfactant. % Is preferably formed by being present in an atmosphere of at least%.

  The porous film may be formed by pressing a mold having a large number of convex portions against a flat surface of a polymer film.

  In this case, the mold having a large number of protrusions may be an electroforming mold or an optical shaping mold.

  Moreover, it is preferable that the said manufacturing method is substantially filled with the said electroconductive particle one by one per said hole part.

Moreover, the said manufacturing method is good to satisfy | fill the conditions of following (1)-(2).
(1) Opening diameter of the hole / particle diameter of the conductive particles: 1 to 1.8
(2) Depth of the hole / particle diameter of the conductive particles: 0.5 to 1

  In the method for producing a particle-filled body according to the present invention, the powdered conductive particles are dispersed on the surface of the porous body, and then the surface of the porous body is removed by a scraping means while attracting the conductive particles to the porous body side by magnetic force. Fray it.

  Therefore, unlike the wet method, there is no need to worry about the solvent resistance of the porous body and the dispersion state of the particles in the dispersion, and the conductive particles are filled in the pores relatively easily by the dry method. be able to.

  In addition, the conductive particles can be reliably filled in the pores by the attractive force to the porous body by the magnetic force and the physical pushing force to the pores by the scraping means. Therefore, it is easy to efficiently fill conductive particles having the same size as the hole.

  At this time, the conductive particles adhering to the surface of the porous body, the agglomerated conductive particles that are not filled in the pores, and the conductive particles that are filled in the pores are adhered due to static electricity or the like. The conductive particles that are present can be forcibly removed at the time of abrasion.

  Here, when the porous body is a porous film having a large number of pores, the particle filler can be used for, for example, an anisotropic conductive film. On the other hand, when the porous body is a mold having a large number of pores, it can be used as a transfer mold for transferring the conductive particles filled in the pores of the mold to another body.

  In addition, the porous membrane is a support obtained by casting a polymer solution containing at least a hydrophobic and volatile organic solvent, a polymer soluble in the organic solvent, and a surfactant. When formed by being present in the above atmosphere, the porous film has pores arranged in a narrow pitch in a honeycomb shape. Therefore, a particle-filled film in which conductive particles are arranged at a narrow pitch in a honeycomb shape can be obtained.

  In addition, when the porous film is formed by pressing a mold having a large number of convex portions against the surface of a flat film made of a polymer, the porous film has an arbitrary arrangement of convex portions. Therefore, the regularity of the holes and the distance between the holes are arbitrarily set.

  Therefore, a particle-filled film having a high degree of design freedom such as regularity of conductive particles and distance between conductive particles can be obtained. Moreover, the selection range of the polymer forming the film is widened, such as the use of a thermosetting resin.

  At this time, when the mold is an electroforming mold or a stereolithography mold, the degree of freedom for forming fine convex portions is increased. Therefore, the above effect can be easily obtained.

  In addition, when the conductive particles are substantially filled one by one per hole, for example, when this is used for an anisotropic conductive film, the connection reliability is improved. There are advantages.

  Further, the ratio of the opening diameter of the hole / the particle diameter of the conductive particles is in the range of 1 to 1.8, and the ratio of the depth of the hole / the particle diameter of the conductive particles is in the range of 0.5 to 1. When it is inside, it becomes easy to fill the conductive particles one by one with respect to each hole.

  Hereinafter, a method for producing a particle packing according to the present embodiment (hereinafter referred to as “the present production method”) will be described in detail.

  In FIG. 1, the outline of the procedure by this manufacturing method is shown. FIG. 2 shows an example of a schematic cross-sectional view of the particle filler obtained by this production method.

  This manufacturing method generally has the following procedure. That is, as shown in FIG. 1A, first, powdered conductive particles 12 are dispersed on the surface of the porous body 10.

  And as shown in FIG.1 (b), the magnetic force generation means 14 is installed in the opposite side to the spreading | diffusion surface of the electroconductive particle 12 of the porous body 10. As shown in FIG.

  Thereafter, as shown in FIG. 1C, the surface of the porous body is scraped off by the scraping means 16 while attracting the dispersed conductive particles 12 to the porous body 10 side by magnetic force.

  Thereby, as shown in FIG. 2, a particle filler 20 in which the conductive particles 12 are filled in the pores 18 of the porous body 10 is obtained.

  Hereinafter, the specific content of this manufacturing method is demonstrated in detail.

  In this production method, the porous body has pores for filling the conductive particles on the surface thereof, and the shape is not particularly limited as long as it is made of a material that does not block magnetic force. .

  In FIG. 1 and FIG. 2, the case where it has a hole on the surface of planar bodies, such as a film | membrane and a flat plate, is illustrated as a porous body, for example. In addition, the porous body may have a hole on the surface of a curved body such as a roll.

  Specific examples of the porous body include a porous film having a large number of pores and a mold having a large number of pores. In the case of a porous membrane, as the material, various resins and polymers such as rubber can be applied. On the other hand, in the case of a mold, various metals (including alloys), ceramics, polymers, and the like can be applied. Since this production method is a dry method, there is no need to consider the solvent resistance of the porous body, and the degree of freedom in selecting the material of the porous body is high.

  This production method can produce a particle packing that is incorporated as all or part of the structure of the product, or a particle packing that is not included in the product but is used when the product is manufactured. It is also possible.

  For example, when the porous body is a porous film, the obtained particle packing can be used for, for example, an anisotropic conductive film, a test film used for a continuity test, a pressure sensitive sensor, and the like.

  Further, when the porous body is a mold, it can be used as a transfer mold for transferring the conductive particles filled in the pores of the mold to another body.

  The hole part which the said porous body has may be a through-hole, and may be a non-through-hole. The hole may have both a through hole and a non-through hole. It can be appropriately selected in consideration of the shape of the porous body. For example, as long as it is a flat body such as a film or a flat plate, either a through hole or a non-through hole can be selected. For a curved body such as a roll, a non-through hole may be selected.

  As the shape of the hole, specifically, for example, a polygonal prism shape such as a quadrangular prism or a triangular prism, a pyramid shape such as a quadrangular pyramid or a triangular pyramid, a cylindrical shape, or a substantially spherical shape (the sphere is crushed. Examples include a substantially hemispherical shape and the like, including the state and the like. Preferably, a shape such as a polygonal column shape, a columnar shape, a substantially spherical shape, or a substantially hemispherical shape is preferable from the viewpoint of preventing the conductive particles filled in the hole from falling off easily.

  Further, the holes may be formed in a regular arrangement such as a lattice shape, a staggered shape, a honeycomb shape, or a stripe shape, or may be formed at random. Preferably, from the viewpoint of increasing the utility value of the particle filler, the holes are preferably arranged regularly. The regular arrangement may be inclined. For example, when the particle filler is used as an anisotropic conductive film, the regular arrangement of conductive particles filled in the holes is pressure-bonded to the arrangement of bumps of the IC chip to be mounted. As described above, when the regular arrangement of the holes is tilted in advance, there is an advantage that it is easy to improve the capturing property of the conductive particles.

  Moreover, the opening diameter of the hole and the depth of the hole can be appropriately selected in consideration of the particle diameter of the conductive particles filled in the hole. Further, the distance between the opening centers of the holes can be appropriately selected in consideration of the use of the particle filler.

  In this production method, it is preferable to fill the conductive particles so that the conductive particles are not stacked in the hole depth direction. In other words, it is preferable to fill the pores with the conductive particles so that they are substantially in the same plane. More preferably, the conductive particles are filled one by one for each hole.

  The upper limit of the ratio of the opening diameter of the hole / the particle diameter of the conductive particles is preferably 1.8 or less, more preferably from the viewpoint of facilitating filling of the conductive particles one by one for each hole. Is 1.6 or less, and more preferably 1.5 or less. On the other hand, the lower limit of the ratio of the opening diameter of the hole / the particle diameter of the conductive particles is preferably 1 or more, more preferably 1.1 or more, and even more preferably 1.2 or more.

  The upper limit of the ratio of the depth of the hole / the particle diameter of the conductive particles is preferably 1 or less, more preferably 0.95 or less, and even more preferably 0.9 or less. On the other hand, the lower limit of the ratio of the depth of the hole / the particle size of the conductive particles is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. .

  At this time, the opening diameter of the hole portion, the depth of the hole portion, and the particle diameter of the conductive particles depend on the use of the obtained particle filler, but basically, all are preferably in the order of μm. .

  For example, when the particle filler is used for an anisotropic conductive film, the upper limit of the particle diameter of the conductive particles is preferably 10 μm or less, although it varies depending on the width and pitch of the conductor of the connected object. More preferably, it should be selected from 7 μm or less, and even more preferably, 5 μm or less. On the other hand, the lower limit of the particle size of the conductive particles is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more.

  In addition, the opening diameter of the said hole is an average value of the diameter of each opening measured by observing the porous body surface with a laser microscope and measuring 10 arbitrarily selected holes. The depth of the hole is an average value of the depth measured with a laser microscope for 10 arbitrarily selected holes. The particle diameter of the conductive particles is an average particle diameter measured with a particle size distribution measuring device (“PITA-1” manufactured by Seishin Enterprise).

  The porous body can be prepared using various methods. For example, when the porous body is a porous film made of a polymer, (1) a support in which the polymer is dissolved in a volatile organic solvent without being mixed with water and the polymer solution is cast, (2) Method of pressing a mold having a large number of protrusions on the surface of a flat film made of various polymers, (3) Drilling on the surface of the film Examples include methods for forming holes by machining, laser processing, chemical and physical etching, and (4) methods for forming porous films having holes using photolithographic methods, stereolithography, etc. can do.

  Among these, the method (1) is preferable from the viewpoint that a porous film having pores arranged in a narrow pitch in a honeycomb shape can be prepared. In addition, from the viewpoint that a porous film in which the regularity of the pores and the distance between the pores are arbitrarily set can be prepared relatively easily, the methods (2) to (4) are preferable, and more preferable. Is the method of (2). Hereinafter, the methods (1) and (2) will be described in order.

  According to the method (1), the porous film is spontaneously formed on the basis of the following principle.

  That is, the polymer solution formed in a film shape with a predetermined coating thickness on the surface of the support is deprived of latent heat when the organic solvent in the solution evaporates. Therefore, a group of minute water droplets formed by condensation of water vapor in the atmosphere adheres to the surface of the polymer solution whose temperature has decreased. The adhering water droplets are transported and collected by convection or capillary force generated in the polymer solution by latent heat, and are finally packed most closely. Thereafter, when the closely packed water droplet group evaporates, a porous film having a honeycomb structure is formed using the self-organized water droplet group as a template.

  The porous membrane formed in this manner basically has the following honeycomb structure regardless of whether it has through holes or non-through holes. Yes.

  That is, the holes are arranged in a honeycomb shape, and the adjacent holes are separated by the partition walls. In addition, since these holes are formed using water droplets as a mold, the inner wall surface thereof is curved in a substantially spherical shape toward the outer side (because it is derived from the surface of the water droplets, the hole diameter is larger than the opening diameter of the holes). The inner diameter of the part is larger). Therefore, the partition wall has a constricted portion having a thinner thickness than the vicinity of the film surface in the vicinity where the inner wall surfaces of the adjacent hole portions are closest to each other.

  The honeycomb structure is usually a structure that is difficult to fabricate using mechanical processing or the like. Therefore, having the honeycomb structure is one of the promising grounds for using a film forming method using water droplets.

  More specifically, the method for forming the porous film of (1) above includes, for example, at least a hydrophobic and volatile organic solvent, a polymer soluble in the organic solvent, and a surfactant. A method in which a support on which a polymer solution containing it is cast is present in an atmosphere having a relative humidity of 50% or more can be suitably used.

  In this case, specific examples of the hydrophobic and volatile organic solvent include halides such as chloroform and methylene chloride, aromatic hydrocarbons such as benzene, toluene and xylene, ethyl acetate, butyl acetate and the like. And ketones such as methyl ethyl ketone (MEK) and acetone. These may be used alone or in combination.

  Specific examples of the polymer include polyvinyl acetal resins such as polyvinyl butyral and polyvinyl formal; polysulfone; polyethersulfone; polyphenylene sulfide; polyimide; polyamideimide; polyetherimide; polyetheretherketone; Polyamide; Polyfluoroethers such as polytetrafluoroethylene; Rubber; Thermoplastic elastomers and the like can be exemplified. These may be contained alone or in combination of two or more.

  More specifically, examples of the polyimide include polyimide containing a siloxane component as a polymerization component.

  More specifically, examples of the polyamideimide include a polyamideimide containing a siloxane component as a polymerization component, and a diisocyanate component having a cyclic hydrocarbon group (an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group). Or, a polyamideimide containing a diamine component and an acid component such as an acid anhydride, polyvalent carboxylic acid or acid chloride as a polymerization component, or a polyamideimide such as polycaprolactone copolymerized with this polyamideimide Can do. These may be contained alone or in combination of two or more.

  More specifically, as the rubber, for example, butadiene rubber, styrene butadiene rubber, isoprene rubber, butyl rubber, urethane rubber, acrylic rubber, silicone rubber, chlorosulfonated polyethylene, epichlorohydrin rubber, nitrile rubber, hydrogenated nitrile rubber, Examples thereof include fluorine rubber, chloroprene rubber, ethylene / propylene / diene terpolymer, and natural rubber. These may be contained alone or in combination of two or more.

  More specifically, the thermoplastic elastomer is, for example, a styrene thermoplastic elastomer, an olefin thermoplastic elastomer, a urethane thermoplastic elastomer, an ester thermoplastic elastomer, an amide thermoplastic elastomer, or a silicone thermoplastic elastomer. Fluorine-based thermoplastic elastomers can be exemplified. These may be contained alone or in combination of two or more.

  The surfactant is added mainly for the purpose of stabilizing water droplets adhering to the surface of the polymer solution. Basically, it is a compound having both a hydrophobic part and a hydrophilic part.

  As the surfactant, specifically, for example, a polymer having a hydrophilic acrylamide polymer as a main chain skeleton, a dodecyl group as a hydrophobic side chain, a lactose group or a carboxyl group as a hydrophilic side chain, Alternatively, a polyionic complex of an anionic polysaccharide such as heparin or dextran sulfate and a quaternary long chain alkyl ammonium salt can be exemplified. These can be used alone or in combination of two or more.

  The upper limit of the concentration of the polymer contained in the polymer solution is preferably 1% by weight or less, more preferably 0.5% by weight or less, and still more preferably, from the viewpoint of retention of water droplets that form condensation. 0.4 wt% or less.

  On the other hand, the lower limit of the concentration of the polymer contained in the polymer solution is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and still more preferably from the viewpoint of water droplet condensation time. Is 0.2% by weight or more.

  In addition, the upper limit of the content of the surfactant is preferably 1 time or less, more preferably 1/2 time or less, and more preferably 1/2 times or less, with respect to the high molecular weight, from the viewpoint of retention of water droplets that form condensation. More preferably, it is 1/4 times or less.

  On the other hand, the lower limit of the content of the surfactant is preferably 1/30 times or more, more preferably 1/20 times or more, with respect to the high molecular weight, from the viewpoint of retention of dewdrops. Even more preferably, the amount is 1/15 times or more.

  While the material of the support for casting the polymer solution does not affect the formation of a liquid film by the polymer solution, it is altered or corroded by an organic solvent or various additives contained in the solution. The material is not particularly limited as long as it is a non-destructive material. Specific examples of the material for the support include inorganic materials such as glass, metal, and silicon wafers, polymer materials such as polypropylene, polyethylene, polyetherketone, and fluororesin, and liquids such as water and liquid paraffin. It can be illustrated.

  The shape of the support is not particularly limited as long as it can stably hold the liquid film formed of the polymer solution on the surface thereof. Usually, for example, a planar shape such as a plate shape or a film shape can be suitably used.

  The coating thickness when casting the polymer solution on the support is appropriately adjusted so that the water droplet group can form through-holes and non-through-holes, taking into account, for example, the concentration of the polymer and the viscosity of the solution. can do.

  The support on which the polymer solution is cast is desirably present in a gas atmosphere having a relative humidity of 50% or more, preferably 50% to 95%. This is because if the relative humidity is within the above range, sufficient condensation is likely to occur.

  At this time, the polymer solution may be cast on a support in an atmosphere having a relative humidity of 50% or more, or the support on which the polymer solution has been cast in advance is placed in an atmosphere having a relative humidity of 50% or more. Also good. Alternatively, a gas having a relative humidity of 50% or more may be blown onto the polymer solution from above or from an oblique direction.

  Specific examples of the gas in the atmosphere and the gas to be sprayed include inert gases such as argon gas and nitrogen gas, and air. These may be contained alone or in combination of two or more. Preferably, air (atmosphere) advantageous in cost is used.

  In this method, it is possible to form both through-holes and non-through-holes by appropriately adjusting the film formation conditions. Specific examples of conditions for forming a film that determines penetration or non-penetration include, for example, the coating thickness (cast amount) of the polymer solution, the concentration of the resin contained in the polymer solution, and the relative humidity. it can.

  More specifically, for example, adjustments such as increasing (increasing) the coating thickness (cast amount) of the polymer solution, increasing the concentration of the resin contained in the polymer solution, and decreasing the relative humidity are performed. For example, non-through holes are easily formed. If the reverse adjustment is performed, the through hole is easily formed.

  Among these, the conditions for determining penetration / non-penetration simply and effectively are the coating thickness (cast amount) of the polymer solution and the concentration of the polymer contained in the polymer solution.

  In order to confirm whether the formed porous membrane has through-holes or non-through-holes, the surface of the membrane is observed to confirm whether the support is exposed in the pores. The film may be peeled off from the support and the back surface of the film may be observed.

  In the method for forming a porous film according to (1) above, a range that does not affect the formation of the porous film as necessary, for example, in order to promote the evaporation of the organic solvent and the evaporation of the water droplet group during the film formation. Inside, heating, drying, etc. may be performed.

  Next, the method for forming the porous film (2) will be described.

  In this method, a mold having a large number of protrusions is pressed against the surface of a flat film made of a polymer (hereinafter sometimes referred to as “flat film”).

  Thereby, many hole parts corresponding to the convex part which the said type | mold has can be formed in the flat membrane surface. In addition, what is necessary is just to select suitably the shape which can form the shape of the said hole part, such as a polygonal column shape and a column shape, as a shape of a convex part.

  Specifically, for example, a mold, a resin mold, or the like can be used as the mold. More specifically, for example, from the viewpoint of a high degree of freedom in forming fine convex portions, an electroforming mold, an optical shaping mold, or the like can be suitably used.

  In particular, when the mold is an electroforming mold, the mold has excellent heat resistance. On the other hand, when the mold is an optical modeling mold, a large-area mold can be prepared relatively inexpensively, and a larger-area particle-filled film can be easily manufactured.

  The material of the electroforming mold is not particularly limited. Usually, a white metal such as nickel, copper, aluminum, chromium, tin, gold, silver, platinum or palladium, or an alloy containing one or more of these can be used. Moreover, the material of the said optical shaping type | mold is not specifically limited. Usually, acrylic resins, epoxy resins, polyethylene resins, polypropylene resins, ABS resins, oxetane resins, and the like can be used.

  In addition, what is necessary is just to prepare the matrix of an electromold using the photolithographic method, the optical modeling method, the inkjet method, laser processing etc., for example.

  In addition, the above-mentioned flat film is prepared by applying a coating solution prepared by adjusting the polymer material forming the above-described flat film so as to have an appropriate solid content and viscosity on a substrate using a known coating means such as a coater. And it can prepare by the method of drying as needed, the method of press-molding the polymeric material which forms the said flat film in flat film shape, etc., It does not specifically limit.

  The pressure applied during the pressing is not particularly limited. Selection may be made in consideration of the type of polymer, the formability of the pores, the strength of the flat film, the thickness of the flat film, and the like. Usually, it is about 0.01-1 MPa.

  Moreover, you may heat at the time of the said press, In that case, heating temperature is not specifically limited. The heating temperature varies depending on the type of polymer to be used, the heat resistance of the mold, and the like, but a temperature of about 20 ° C. to + 40 ° C. is preferably selected. It is because it becomes easy to form a hole in a flat membrane.

  On the other hand, for example, when the porous body is a mold, a method of forming a hole by drilling, laser processing, chemical or physical etching on the surface of the mold material, a photolithography method, an optical modeling method, etc. The porous mold can be prepared using a method of forming a mold having pores.

  Specifically, for example, a mold, a resin mold, or the like can be used as the mold. More specifically, for example, from the viewpoint of a high degree of freedom in forming fine holes, an electroforming mold, an optical shaping mold, or the like can be suitably used.

  In particular, when the mold is an electroforming mold, the mold has excellent heat resistance. On the other hand, when the mold is an optical modeling mold, a large-area mold can be prepared relatively inexpensively, and a larger-area particle filler can be easily manufactured.

  The material of the electroforming mold is not particularly limited. Usually, a white metal such as nickel, copper, aluminum, chromium, tin, gold, silver, platinum or palladium, or an alloy containing one or more of these can be used. Moreover, the material of the said optical shaping type | mold is not specifically limited. Usually, acrylic resins, epoxy resins, polyethylene resins, polypropylene resins, ABS resins, oxetane resins, and the like can be used.

  In addition, what is necessary is just to prepare the matrix of an electromold using the photolithographic method, the optical modeling method, the inkjet method, laser processing etc., for example.

  In this manufacturing method, powdery conductive particles are dispersed on the surface of a porous body such as the porous film prepared as described above. In addition, as long as electroconductive particle can be spread on the surface of a porous body, any method may be used for a dispersion | spreading means, and it will not be specifically limited.

  Here, powder particles are used as the conductive particles. That is, in this manufacturing method, it is not necessary to disperse the conductive particles in a solvent or the like.

  Specific examples of the conductive particles include a substantially spherical shape (including those having a substantially elliptical cross section), a substantially columnar shape, a spindle shape, and a needle shape. Preferably, it is preferable to have a substantially spherical shape from the viewpoint of easy filling of the conductive particles in the pores of the porous body.

  The conductive particles can be applied to any structure and material as long as they have conductivity and magnetism.

  Specific examples of the conductive particles include, for example, particles that are filled with a conductive substance from the surface to the center thereof, and the surface of the polymer particles that are coated with one or more conductive layers. The particle | grains etc. which can be illustrated can be illustrated.

  The latter particles are preferably used. Since the particles are easily elastically deformed by pressurization, when the obtained particle filler is used, for example, in an anisotropic conductive film, the contact area with the conductor of the connected object is increased during crimping, This is because it becomes easy to ensure conductivity in the film thickness direction.

  More specifically, for example, as an example of the former particles, metal particles, carbon particles and the like are used, and as an example of the latter particles, one or two or more metal plating layers (electrolytic plating, Electrolytic plating etc.) and particles having a sputtered layer can be exemplified.

  Specific examples of metals that can be used in the conductive material and conductive layer include gold, silver, white metals (platinum, palladium, ruthenium, rhodium, osmium, iridium), nickel, copper, zinc, and iron. 2 such as lead, tin, aluminum, cobalt, indium, chromium, titanium, antimony, bismuth, germanium, cadmium, etc., tin-lead alloy, tin-copper alloy, tin-silver alloy, tin-lead-silver alloy, etc. Examples include alloys composed of more than one kind of metal. These may be contained alone or in combination of two or more.

  Specific examples of the polymer applicable to the polymer particles include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyisobutylene, polybutadiene, polyalkylene terephthalate, polysulfone, Polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, (meth) acrylic acid ester polymer, divinylbenzene polymer, divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid Examples thereof include divinylbenzene polymers such as ester copolymers. These may be contained alone or in combination of two or more. In addition, the said (meth) acrylic acid ester may be bridge | crosslinked as needed.

  Preferred are dimethybenzene-based polymers such as (meth) acrylic acid ester polymers, divinylbenzene polymers, divinylbenzene-styrene copolymers and divinylbenzene- (meth) acrylic acid ester copolymers.

Further, in the present manufacturing method, particles in which one or two or more insulating layers made of an insulating oxide such as TiO ₂ or the above polymer are coated on the surface of the conductive particles may be used.

  In addition, in this manufacturing method, you may use together 1 type, or 2 or more types of above-mentioned electroconductive particle. The particle size of the conductive particles is as described above in relation to the pores of the porous body.

  In this production method, the conductive particles are attracted to the porous body side by a magnetic force. The magnetic force generating means used at this time is not particularly limited. Specifically, for example, a permanent magnet or an electromagnet may be used. These may be used alone or in combination of two or more.

  At this time, it is preferable that the magnetic force generating means is installed on the opposite side of the porous body from the conductive particles. This is because it is easy to attract the conductive particles to the porous membrane side by applying a magnetic force to the conductive particles through the porous membrane.

  The magnetic force to be applied varies depending on the material of the conductive particles. Basically, if the magnetic force is too small, the conductive particles cannot be sufficiently attracted to the porous membrane side, and the particle filling property tends to be lowered. On the other hand, if the magnetic force is excessively large, there is a tendency that the conductive particles and the like that have not been introduced into the hole portion are not easily scraped off when scraped by the scraping means. Therefore, the magnetic force generated by the magnetic force generation means may be selected in consideration of these points.

  In this production method, the surface of the porous body is scraped off by the scraping means in a state where the conductive particles are attracted to the porous membrane side by magnetic force as described above.

  Any means can be used as the scrubbing means as long as it can press the conductive particles against the surface of the porous body and scrub the conductive particles. Specific examples of the abrasion means include, for example, brushes, brushes (made of metal, resin, etc.), blades, non-woven fabrics, glass fibers, and glass beads (spreading glass beads on the surface of the porous body and rolling the surface) Etc.) and the like. These may be used alone or in combination of two or more.

  In the present manufacturing method, it is basically sufficient to carry out the scraping only once, but this does not preclude it from being carried out a plurality of times if necessary. In addition, when the abrasion is performed a plurality of times, the conductive particles may be dispersed a plurality of times in accordance with the abrasion.

  According to the present manufacturing method, the conductive particles can be reliably filled in the hole portion by the above operation by the attractive force to the porous body by the magnetic force and the physical pushing force to the hole portion by the scraping means. . Moreover, it is easy to efficiently fill the conductive particles having almost the same size as the holes.

  At this time, the conductive particles adhering to the surface of the porous body, the agglomerated conductive particles that are not filled in the pores, and the conductive particles that are filled in the pores are adhered due to static electricity or the like. The conductive particles and the like that are present can be almost forcibly removed at the time of abrasion.

  However, from the viewpoint of ensuring the removal of the conductive particles and the like attached to the surface of the porous body, the surface of the porous body is further removed using an adhesive tape, if necessary, after the above abrasion. You may add the process of removing the electroconductive particle etc. which have adhered to.

  Hereinafter, the present invention will be described in detail using examples.

1. Production of Particle Packing Film (Examples 1 to 3, Comparative Examples 1 to 5) and Particle Packing Type (Examples 4 to 5) (Example 1)
First, a porous membrane was prepared as follows. That is, as a surfactant, a polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., “ESREC KS-3Z” residual hydroxyl group amount: 25 mol%) dissolved in chloroform so as to have a concentration of 0.26 wt%. A polymer solution was prepared by adding 0.026 wt% of a copolymer of dodecylacrylamide and caproic acid to the polyvinyl butyral resin.

  Next, the polymer solution was cast on a glass substrate with an applied film thickness of 1100 μm in an atmosphere at a temperature of 22 ° C. and a relative humidity of 57%. Thereafter, using an air pump, air having the same temperature and humidity as described above (flow rate 2 L / min) was continuously blown onto the coating liquid surface for 30 minutes from an angle of 20 °.

  As a result, water droplets due to condensation adhere to the polymer solution surface along with the volatilization of chloroform, and after this close-packed, the water droplets evaporate, resulting in a large number of pores (non-through holes) arranged in a honeycomb shape. A porous film (film thickness 5 μm) made of polyvinyl butyral resin was obtained.

  In addition, about the obtained porous membrane, the distance between the opening diameter of a hole part, the depth of a hole part, and the opening center of an adjacent hole part is measured with a laser microscope (ultra-depth color 3D shape measurement microscope, Keyence Corporation "VK. -9500 "). As a result, they were 5 μm, 4 μm, and 6 μm, respectively.

  Next, powder-like resin plating particles (Sekisui Chemical Co., Ltd., “Micropearl AU-204”) in which Ni plating layer and Au plating layer are sequentially coated on the surface of particles made of divinylbenzene-based crosslinked resin, An average particle diameter of 4 μm) was sprayed on the pore-forming surface of the porous membrane.

  Next, with a permanent magnet (manufactured by Seiko Sangyo Co., Ltd., ferrite magnet, 1000 gauss) installed on the side opposite to the hole forming surface, the resin plating particles are attracted to the porous membrane, and the membrane surface is brushed After scraping once, resin plating particles were introduced into the hole.

  Resin plating particles adhering to the surface of the porous film in which no pores are formed or resin plating particles adhering to the resin plating particles introduced into the holes due to electrostatic force, etc. Almost removed.

  Thereby, the particle filling film | membrane which concerns on Example 1 with which the resin plating particle was filled in the hole part of the porous film made from a polyvinyl butyral resin was obtained. The resin plating particles were substantially filled one by one for each hole.

(Example 2)
A porous membrane was prepared in the following manner. That is, a polybutadiene rubber (manufactured by JSR, “RB820”) dissolved in chloroform so as to have a concentration of 0.26 wt%, a copolymer of dodecylacrylamide and caproic acid as a surfactant is added to the polybutadiene rubber. On the other hand, 0.026 wt% was added to prepare a polymer solution.

  Next, the polymer solution was cast on a glass substrate with an applied film thickness of 1100 μm in an atmosphere at a temperature of 22 ° C. and a relative humidity of 57%. Thereafter, air having the same temperature and humidity as described above (flow rate: 5 L / min) was continuously sprayed from the angle of 45 ° for 15 minutes using an air pump.

  As a result, in the same manner as in Example 1, a polybutadiene rubber porous film (film thickness: 5 μm) having a large number of pores (non-through holes) arranged in a honeycomb shape was obtained.

  In addition, the opening diameter of the hole part of the obtained porous membrane, the depth of a hole part, and the distance between the opening centers of an adjacent hole part were 5 micrometers, 4 micrometers, and 6 micrometers, respectively.

  Thereafter, in the same manner as the production of the particle-filled film according to Example 1, a particle-filled film according to Example 2 in which resin plating particles were filled in the pores of the porous film made of polybutadiene rubber was obtained. The resin plating particles were substantially filled one by one for each hole.

(Example 3)
A porous membrane was prepared in the following manner. That is, 23.39 parts by weight of an alcohol-soluble polyamide resin, 25.16 parts by weight of a phenoxy resin (manufactured by Toto Kasei Co., Ltd., “EFR-0010M30”), and an epoxy resin (manufactured by Toto Kasei Co., Ltd., “FX289EK75”). 4.9 parts by weight, 2.67 parts by weight of epoxy resin (manufactured by Toto Kasei Co., Ltd., “FX305EK70”) and 1.37 parts of melamine resin (manufactured by Sanwa Chemical Co., Ltd., “Nicarac MX-750”) 1.37 Parts by weight, curing agent (Shikoku Kasei Co., Ltd., "C11Z") 0.38 parts by weight, curing agent (Mitsubishi Gas Chemical Co., Ltd., "F-TMA") 0.57 parts by weight, methanol 24.26 parts by weight, 48.05 parts by weight of toluene, and 69.2 parts by weight of methyl cellosolve were mixed to prepare a polymer solution.

  Next, the polymer solution was applied to the release surface of a base substrate (polyethylene terephthalate, thickness 38 μm, “PET 38X” manufactured by Lintec Corporation) using a comma coater.

  Next, this coating layer was dried at 160 ° C. for 90 seconds to form a flat film (thickness 4 μm) made of a resin mainly composed of polyamide resin and phenoxy resin. Thereafter, the release surface of the separator (polyethylene terephthalate, thickness 75 μm, manufactured by Lintec Corporation, “PET75C”) was put on the surface of the flat film and wound up.

  In this way, a resin flat film having polyamide resin and phenoxy resin as main components was prepared.

  Next, an optical modeling mold having a large number of convex portions (convex portion diameter 5 μm square, convex height 3.5 μm, pitch = distance 10 μm between adjacent convex centers) arranged in a staggered manner was prepared. .

  Next, the convex surface of the stereolithography mold was pressed against the surface of the flat film exposed by peeling the separator with a press (pressure 0.1 MPa, temperature 130 ° C.).

  As a result, a porous film made of a resin mainly composed of a polyamide resin and a phenoxy resin having a large number of holes (non-through holes) arranged in a staggered pattern was obtained.

  In addition, the opening diameter of the hole part of the obtained porous membrane, the depth of a hole part, and the distance between the opening centers of an adjacent hole part were 5 micrometers, 3.5 micrometers, and 10 micrometers, respectively. In addition, the numerous holes were regularly arranged in a zigzag shape with the whole inclined at about 8 °.

  Thereafter, similarly to the particle-filled film according to Example 1, particles according to Example 3 in which resin-plated particles are filled in the pores of a resin-made porous film mainly composed of a polyamide resin and a phenoxy resin. A packed membrane was obtained. The resin plating particles were substantially filled one by one for each hole.

Example 4
In the production of the particle-filled film according to Example 1, in place of the porous film, a large number of holes arranged in a staggered manner (a substantially cylindrical shape with an opening diameter of 5 μm and a hole depth of 3.5 μm, pitch = adjacent In the same manner, except that a Ni electroforming mold having a distance of 10 μm between the opening centers is dispersed and the resin plating particles are dispersed on the hole forming surface of this mold, the resin plating particles are placed in the pores of the Ni electroforming mold. A filled particle-packing mold according to Example 4 was obtained. The resin plating particles were substantially filled one by one for each hole.

(Example 5)
In the production of the particle-filled film according to Example 1, instead of the porous film, a large number of holes arranged in a staggered pattern (opening 5 μm square, approximately prismatic shape with a hole depth of 3.5 μm, pitch = In the same manner, except that a stereolithography mold having a distance of 10 μm between adjacent opening centers is prepared and the resin plating particles are dispersed on the hole forming surface of this mold, resin plating particles are placed in the stereolithography mold holes. A particle-packed mold according to Example 4 was obtained. The resin plating particles were substantially filled one by one for each hole.

(Comparative Example 1)
In the same manner as in Example 2, a porous film made of polybutadiene rubber was prepared.

  Next, another glass substrate is placed at a certain distance from the porous film fixed on the glass substrate, and a dispersion solution of silver nanoparticles having a concentration of 3 wt% (Japan) is placed in the gap between the porous film and the other substrate. “Fine Sphere SVW102” manufactured by Paint, average particle diameter of silver nanoparticles 50 nm) was injected and held by surface tension.

  Next, the other glass substrates were slid at a constant speed (5 to 10 μm / sec) to separate the glass substrates from each other.

  As a result, a particle-filled film according to Comparative Example 1 in which a large number of silver nanoparticles were filled in each pore of the porous film made of polybutadiene rubber was obtained.

(Comparative Example 2)
In the same manner as in Example 2, a porous film made of polybutadiene rubber was prepared.

  Next, another glass substrate is arranged at a certain distance from the porous membrane fixed on the glass substrate, and resin plating particles (Sekisui Chemical Co., Ltd., “ A dispersion solution (solvent: ethanol, concentration 1 wt%) of “Micropearl AU-204”, average particle size 4 μm) was injected and held by surface tension.

  Next, the other glass substrates were slid at a constant speed (5 to 10 μm / sec) to separate the glass substrates from each other. Thereafter, the injection of the dispersion solution and the slide movement were repeated, and the particle filling operation was performed 10 times in total.

  Thereby, the particle filling film | membrane which concerns on the comparative example 2 with which the resin plating particle was filled in the hole part of the porous film made from polybutadiene was obtained.

(Comparative Example 3)
In the same manner as in Example 1, a porous membrane made of polyvinyl butyral resin was prepared.

  Next, another glass substrate is arranged at a certain distance from the porous membrane fixed on the glass substrate, and resin plating particles (Sekisui Chemical Co., Ltd., “ A dispersion solution (solvent: ethanol, concentration 1 wt%) of “Micropearl AU-204”, average particle size 4 μm) was injected and held by surface tension.

  Next, the other glass substrates were slid at a constant speed (5 to 10 μm / sec) to separate the glass substrates from each other.

  However, the porous membrane was dissolved and a particle-filled membrane could not be produced.

(Comparative Example 4)
In the same manner as in Example 1, a porous membrane made of polyvinyl butyral resin was prepared.

  Next, another glass substrate is arranged at a certain distance from the porous membrane fixed on the glass substrate, and resin plating particles (Sekisui Chemical Co., Ltd., “ A dispersion solution (solvent: hexane, concentration 0.5 wt%) of “Micropearl AU-204”, average particle size 4 μm) was injected and held by surface tension.

  Next, the other glass substrates were slid at a constant speed (5 to 10 μm / sec) to separate the glass substrates from each other. Thereafter, the injection of the dispersion solution and the slide movement were repeated, and the particle filling operation was performed 20 times in total.

  Thereby, the particle filling film | membrane which concerns on the comparative example 4 with which the resin plating particle was filled in the hole part of the porous film made from a polyvinyl butyral resin was obtained.

(Comparative Example 5)
In the same manner as in Example 2, a porous film made of polybutadiene rubber was prepared.

  Thereafter, in the production of the particle-filled film according to Example 1, a comparison was made in the same manner except that the operation of scrubbing the dispersed resin plating particles without attracting the porous film was performed five times without using a permanent magnet. A particle-filled film according to Example 5 was produced.

2. Evaluation of Particle Packing Film Of the above prepared particle packing films, those having a porous film material other than polybutadiene rubber (Example 1, Example 3, Comparative Example 4) are provided on the particle packing surface side with an adhesive layer. (Thickness 20 μm) was pasted to make each anisotropic conductive film.

  On the other hand, among each of the produced particle-filled films, the material of the porous film is polybutadiene rubber (Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 5). An adhesive layer (thickness: 2 μm) was attached to the opposite side of the particle-filled surface, and each anisotropic conductive film was formed.

  The adhesive layer was composed of 90 parts by weight of dicyclopentadiene type epoxy resin (Dainippon Ink Co., Ltd., “Epiclon HP7200HH”) and nitrile rubber (NBR) (Nippon Zeon Co., Ltd., “Nipol 1072J”). A comma coater was prepared by diluting 10 parts by weight and 187 parts by weight of a curing agent (“Novacure HXA3932HP” manufactured by Asahi Kasei Chemicals Corporation) with toluene so that the solid content was 42%. Was applied to the release surface of a base substrate (polyethylene terephthalate, thickness 38 μm, “PET38C” manufactured by Lintec Corporation) and dried at 110 ° C. for 90 seconds.

  And about the produced said anisotropic conductive film, the conduction performance of the film thickness direction and the insulation performance of the film surface direction were evaluated.

(Preparation of evaluation sample)
That is, first, an anisotropic conductive film is placed on a circuit pattern (material ITO, pattern pitch 30 μm, pattern width 20 μm) formed on the surface of a 0.7 mm thick glass substrate, and the temperature is 110 ° C. on the circuit pattern. Temporary pressure bonding was performed on the bonded anisotropic conductive film under the conditions of a pressure of 0.25 MPa and a pressure bonding time of 5 seconds.

  Next, an IC chip having an Au bump (bump pitch 30 μm, bump width 20 μm) was placed on the temporarily pressure-bonded anisotropic conductive film so that the circuit pattern and the Au bump faced each other.

  Next, in this state, the main pressure bonding was performed under the conditions of a temperature of 210 ° C., a pressure of 80 MPa, and a pressure bonding time of 60 seconds. After the main pressure bonding, cooling was subsequently performed under the conditions of a temperature of 50 ° C., a pressure of 80 MPa, and a time of 5 seconds.

  Thus, Samples 1 to 3 and Comparative Samples 1, 2, 4, and 5 were produced. Note that the numbers of the sample and the comparative sample correspond to the numbers of the example and the comparative example.

(Evaluation of conduction performance in the film thickness direction)
With respect to each of the obtained samples, the electric resistance between the circuit pattern and the Au bump that face each other was measured by a four-terminal four-probe method using a resistivity meter (“Loresta GP” manufactured by Dia Instruments). The number of each sample was N = 5 [pieces], and an average value was calculated by arithmetic average, and this was taken as the electric resistance in the film thickness direction.

(Evaluation of insulation performance in the film surface direction)
About each obtained sample, the electrical resistance between adjacent circuit patterns was measured using tester T2 (the product made by AND, "AD5522"). The number of each sample was N = 5 [pieces], and an average value was calculated by arithmetic average, and this was taken as the electric resistance in the film surface direction.

(Evaluation results)
Table 1 summarizes the evaluation results of each sample.

(Discussion)
A relative comparison of Table 1 shows the following.

  That is, Comparative Sample 1 uses a particle-filled film according to Comparative Example 1 in which a large number of nanometer-order silver nanoparticles are filled in a pore of μm order by a wet method (slide method). In comparison, the electric resistance in the film thickness direction was large. This is presumably because the contact resistance of the silver nanoparticles is involved in the film thickness direction, so that the electrical resistance is increased as compared with the others.

  Comparative sample 2 uses a particle-filled film according to Comparative Example 2 filled with resin plating particles of μm order in a hole of μm order by a wet method (slide method). In order to obtain the same resistance value, it was necessary to repeat the slide operation 10 times. This is because the resin plating particles are likely to aggregate in the used particle dispersion, so that it is difficult to fill the pores with the slide operation. From this, it can be seen that it is disadvantageous to fill the hole with conductive particles having a size approximately equal to the size of the hole by the slide method.

  Comparative sample 4 uses a particle-filled film according to comparative example 4 in which resin plating particles of μm order are filled in a hole of μm order by a wet method (slide method). Furthermore, many slide operations were necessary. This is because the dispersibility of the resin plating particles is poor in the solvent in which the porous film of Comparative Example 4 does not dissolve, and the resin plating particles can be dispersed only at a concentration about 1/2 times that of Comparative Example 2. . From this, it can be said that the slide method has poor particle packing efficiency. As can be seen from the results of Comparative Example 3, it can also be seen that depending on the material of the porous membrane, the particles may be dissolved by the solvent of the particle dispersion and the particles may not be filled.

  On the other hand, Sample 1 to Sample 3 use the particle packed films according to Examples 1 to 3 manufactured by applying the manufacturing method of the present invention.

  Therefore, unlike the wet method, there is no need to worry about the solvent resistance of the porous membrane and the dispersion state of the particles in the particle dispersion, and the dry method is relatively easy to obtain the same size as the pores. As a result of reliably filling the hole with the conductive particles, it was possible to ensure conductivity in the film thickness direction and insulation in the film surface direction.

  Sample 2 and comparative sample 5 have the same electrical resistance in the film thickness direction, but the presence or absence of magnetic action during the production of the particle-filled film (Sample 1: Yes, Comparative Sample 5: No), There is a difference in the number of wears (sample 1: 1, comparison sample 5: 5).

  From this, it can be said that according to the production method of the present invention, by applying a magnetic force at the time of scraping, the pores can be efficiently filled with conductive particles with fewer operations.

  Therefore, from these results, according to the method for producing a particle packing according to the present invention, it is easier and more reliable to fill the pores of the porous body with conductive particles compared to the conventional method. It was confirmed that can be manufactured.

  Although one embodiment and one example of the present invention have been described above, the present invention is not limited to the above embodiment and example, and various modifications can be made without departing from the spirit of the present invention. is there.

It is the figure which showed the outline of the procedure by this manufacturing method of the particle filler which concerns on this embodiment. It is an example of the typical sectional view of the particle packing obtained by this manufacturing method of the particle packing concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Porous body 12 Conductive particle 14 Magnetic force generation means 16 Wearing means 18 Hole part 20 Particle packing body

Claims (7)

  After spraying the conductive particles in the form of powder on the surface of the porous body, the surface of the porous body is scraped off by a scraping means while attracting the conductive particles to the porous body side by magnetic force, and in the pores of the porous body. A method for producing a particle filler for filling conductive particles.   The method for producing a particle filler according to claim 1, wherein the porous body is a porous film having a large number of pores or a mold having a large number of pores.   The porous membrane comprises a support obtained by casting a polymer solution containing at least a hydrophobic and volatile organic solvent, a polymer soluble in the organic solvent, and a surfactant at a relative humidity of 50% or more. It is formed by making it exist in atmosphere, The manufacturing method of the particle filler of Claim 2 characterized by the above-mentioned.   The method for producing a particle filler according to claim 2, wherein the porous film is formed by pressing a mold having a large number of convex portions against a flat film surface made of a polymer.   The method according to claim 4, wherein the mold is an electroforming mold or an optical shaping mold.   The method for producing a particle filler according to any one of claims 1 to 5, wherein the conductive particles are substantially filled one by one for each of the holes. The method for producing a particle filler according to any one of claims 1 to 6, wherein the following conditions (1) to (2) are satisfied.
(1) Opening diameter of the hole / particle diameter of the conductive particles: 1 to 1.8
(2) Depth of the hole / particle diameter of the conductive particles: 0.5 to 1

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