JP2008186761A - Method for producing particle transfer film, method for producing particle holding film, and anisotropic conductive film - Google Patents

Abstract

An object of the present invention is to provide a technique capable of arranging conductive particles at a narrow pitch in a honeycomb shape and expanding the selection range of a film material for holding the conductive particles.
In manufacturing a particle transfer film by transferring conductive particles held in pores of a porous film to a polymer flat film surface, the conductive particles are formed from water droplets and have a honeycomb shape. A porous membrane having a large number of pores arranged in a column is used. The conductive particles of the particle transfer film thus obtained are embedded and held in a flat film to produce a particle holding film.
[Selection] Figure 1

Description

  The present invention relates to a method for producing a particle transfer film, a method for producing a particle holding film, and an anisotropic conductive film.

  Recently, in various industrial fields, opportunities for regularly arranging conductive particles are increasing.

  For example, in the fields of electric and electronic devices, a particle holding film in which regularly arranged conductive particles are held in a film is used as a skeleton of an anisotropic conductive film.

  This type of anisotropic conductive film is suitably used, for example, when electrically and mechanically connecting a circuit pattern of a circuit board and an IC chip.

  In recent years, miniaturization and high functionality of electric and electronic devices have been achieved, and miniaturization of circuit patterns and the like is also progressing. For this reason, there is a demand for an anisotropic conductive film having conductive particles arranged in a narrow pitch in conjunction therewith.

  For this reason, a technique for arranging conductive particles at a narrow pitch is required.

  As a technique for arranging the conductive particles, for example, in Patent Document 1, after forming a magnetic recording region on a magnetic medium, the conductive particles are captured in the magnetic recording region, and the conductive particles are made sticky. A technique is disclosed in which particles are arranged by transferring onto a substrate having the same. In addition, a method for manufacturing an anisotropic conductive film by applying this technique is also disclosed.

  Then, using the above technique, the conductive particles are actually trapped in the belt-shaped magnetic recording region (the conductive particles are continuous in the band length direction, and the band width is 3 to 4). It is composed of conductive particles), which is transferred to an insulating adhesive and fixed to produce an anisotropic conductive film.

  Further, for example, in Patent Document 1 by the present applicant, water droplets are condensed on the surface of the polymer solution in a high humidity atmosphere, and after forming a porous film using the water droplet group as a template, conductive particles are placed in the pores. A technique for arranging particles by packing is disclosed. In addition, a method for manufacturing an anisotropic conductive film by applying this technique is also disclosed.

JP 2006-24551 A International Publication No. WO2005 / 096442 Pamphlet

  However, the prior art has problems in the following points.

  That is, in the technique of Patent Document 1, since the conductive particles adhere to each other due to magnetism, it is considered extremely difficult to arrange the individual conductive particles apart from each other and regularly arrange them in a honeycomb shape. .

  On the other hand, the technique of Patent Document 2 is a technique suitable for arranging conductive particles at a narrow pitch in a honeycomb shape.

  However, this technique requires the use of a hydrophobic polymer in order to stably condense water droplets on the surface of the polymer solution. Therefore, there is a restriction on the material of the film for regularly arranging and holding the conductive particles. Further, for example, when an anisotropic conductive film is manufactured using the particle holding film according to this technique, there is a problem that the range of selection of a polymer material for forming the anisotropic conductive film is narrowed.

  The present invention has been made in view of the above problems, and can arrange conductive particles at a narrow pitch in a honeycomb shape, and can widen the selection range of a film material holding the conductive particles. To provide technology.

  In order to solve the above-mentioned problems, the present inventors have made various studies. As a result, the porous film having a honeycomb structure may be used as a transfer mold, not directly as a film for holding conductive particles. It came to obtain the knowledge that it might be. The present invention has been made mainly based on the above findings.

  That is, in the method for producing a particle transfer film according to the present invention, when transferring the conductive particles held in the pores of the porous film to the surface of the polymer flat film, the porous film is derived from water droplets. The gist of the present invention is to use a porous film that is formed in a honeycomb shape and has a large number of pores arranged in a honeycomb shape.

  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%.

  Further, heating and / or pressurization may be performed during the transfer.

When heating is performed at the time of the transfer, the heating is preferably performed at a temperature at which the viscosity of the polymer forming the flat film is 2 × 10 ⁴ Pa · s or less.

  On the other hand, the method for producing a particle holding film according to the present invention is to produce a particle holding film by embedding and holding the conductive particles of the particle transfer film obtained as described above in a flat film. And

  In the method for producing a particle transfer film according to the present invention, the conductive particles held in the pores of the porous film are transferred to the surface of the polymer flat membrane to produce the particle transfer film. A porous membrane having a large number of pores arranged in a honeycomb shape is used.

  Therefore, it is possible to transfer the conductive particles arranged in a narrow pitch in a honeycomb shape. Therefore, if this particle transfer film is used, the transferred conductive particles are held in the film while maintaining the state, thereby holding the particles in which the conductive particles are held in a honeycomb-like arrangement at a narrow pitch. A film can be obtained.

  Further, according to the particle transfer film, the porous film itself having a honeycomb structure is not included in a part of the particle transfer film. Therefore, the selection range of the polymer material forming the particle transfer film is expanded, and as a result, the selection range of the polymer material forming the particle holding film formed using the particle transfer film is also expanded.

  Therefore, when the present invention is applied to an anisotropic conductive film, conductive particles are arranged in a narrow pitch in a honeycomb shape, and the degree of freedom in selecting a film material that holds the conductive particles is high. There is an advantage that a isotropic conductive film can be obtained.

  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. %, It is easy to obtain a porous film whose pores are arranged in a honeycomb shape and whose inner wall surface is curved outward.

  Further, when heating and / or pressurization is performed during the transfer, the transferability of the conductive particles is improved.

In particular, when heating is performed at a temperature at which the viscosity of the polymer forming the flat film is 2 × 10 ⁴ Pa · s or less during the transfer, the conductive particles tend to bite into the surface of the flat film, which is good. It is easy to secure a high transfer rate.

  On the other hand, according to the method for producing a particle holding film of the present invention, the conductive particles of the particle transfer film are embedded and held in a flat film.

  Therefore, a particle holding film having a particle arrangement that the particle transfer film has can be easily obtained.

  Hereinafter, the manufacturing method of the particle transfer film according to the present embodiment (hereinafter referred to as “first manufacturing method”) and the manufacturing method of the particle holding film according to the present embodiment (hereinafter referred to as “second manufacturing method”). ) Will be described in detail.

1. First Manufacturing Method The first manufacturing method is a method of manufacturing a particle transfer film by transferring conductive particles held in the pores of a porous film to a polymer flat film surface.

  FIG. 1 is a diagram showing an outline of the first manufacturing method. That is, as shown in FIG. 1A, first, a porous film 14 in which the conductive particles 12 are held in the holes 10 and a flat film 16 made of a polymer are prepared.

  Then, as shown in FIG. 1B, the conductive particles 12 are transferred from the porous film 14 to the flat film 16 surface. Thereby, the particle transfer film 18 is obtained.

(Porous membrane)
The first manufacturing method uses a porous film as a transfer mold. This porous film is obtained by a film forming method using water droplets, and the material is basically a polymer (described later) that can be applied to the film forming method. , Any polymer may be used.

  The porous membrane is formed from water droplets and has a large number of pores arranged in a honeycomb shape.

  The hole may be a through hole or a non-through hole. The hole may have both a through hole and a non-through hole. Preferably, it is a non-through hole from the viewpoint that the held conductive particles are difficult to drop off.

  Moreover, the opening diameter of the said hole part and the depth of a hole part will not be specifically limited if electroconductive particle is hold | maintained and transcription | transfer can be performed. Basically, it can be selected in consideration of the particle size of the conductive particles used.

  From the viewpoint of good holding of the conductive particles, easy holding of the conductive particles one by one for each hole, the upper limit of the ratio of the opening diameter of the holes / the particle diameter of the conductive particles is, Preferably, it is 1.8 or less, more preferably 1.6 or less, and even 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.

  In addition, the upper limit of the ratio of the depth of the pores / the particle size of the conductive particles from the viewpoint of good transferability of the conductive particles and easy holding of the conductive particles one by one. 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, the depth of the hole, and the particle diameter of the conductive particles are basically in the order of μm, although depending on the use of the obtained particle transfer film.

  For example, when the particle transfer film 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.

  The upper limit of the interval between the holes is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. On the other hand, the lower limit of the interval between the holes 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 part is an average value of the diameter of each opening part which observed the porous membrane surface with the laser microscope, and measured about 10 hole parts selected arbitrarily. 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 space | interval of the said hole part is an average value of the distance between each opening edge measured by observing the porous membrane surface with a laser microscope, and measuring about 10 places between the opening edge parts of the adjacent hole part selected arbitrarily.

  Specifically, the porous membrane is a method in which a polymer is dissolved in a volatile organic solvent that is not mixed with water, and the support obtained by casting the polymer solution is present in a high humidity atmosphere (water droplets due to condensation). Can be prepared using a film forming method using According to this method, it is easy to prepare a porous film having pores arranged in a narrow pitch in a honeycomb shape. Hereinafter, this method will be described in order.

  According to this method, 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 formed in a honeycomb shape and at a narrow pitch because the holes are formed by using a closely packed water droplet group as a mold. However, adjacent hole portions are separated by a partition formed by a polymer solution that has entered a gap between adjacent water droplets. In addition, since the hole is formed using a water drop 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 drop, the hole is formed from the opening diameter of the hole. The inner diameter of is larger).

  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 is, for example, a polymer solution containing at least a hydrophobic and volatile organic solvent, a polymer soluble in the organic solvent, and a surfactant. For example, a method in which a support obtained by casting 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, for example, polyvinyl acetal resins such as polyvinyl butyral and polyvinyl formal; polysulfone; polyethersulfone; polyphenylene sulfide; polyimide; polyamideimide; polyetherimide; polyetheretherketone; Examples thereof include polyamide; polyphenylene ether; fluorine resin such as polytetrafluoroethylene; rubber; thermoplastic elastomer. 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 polymer contained in the polymer solution, and the relative humidity. Can do.

  More specifically, for example, adjustments such as increasing (increasing) the coating thickness (cast amount) of the polymer solution, increasing the concentration of the polymer contained in the polymer solution, and decreasing the relative humidity, etc. If it does, it will become easy to form a non-through-hole. 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, heating is performed within a range that does not affect the formation of the porous film, if necessary, in order to promote the evaporation of the organic solvent and the evaporation of water droplets during film formation. Drying or the like may be performed.

  Moreover, after forming the said porous film, you may pressurize within the range which does not destroy a porous film from a viewpoint of improving the flatness of a film | membrane. In addition, you may heat at the time of this pressurization.

(Conductive particles)
Specific examples of the conductive particles used in the first production method include, for example, a substantially spherical shape (including those having a substantially elliptical cross section), a substantially columnar shape, a spindle shape, and a needle shape. . Preferably, the spherical shape is preferable from the viewpoint of easily holding the conductive particles in the pores of the porous membrane.

  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 anisotropic conductive film is manufactured using the obtained particle transfer film, for example, the connected object has at the time of pressure bonding of the anisotropic conductive film. This is because the contact area with the conductor is increased and it is 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 first 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 the first manufacturing method, the above-described conductive particles may be used alone or in combination of two or more. The particle size of the conductive particles is as described above in relation to the pores of the porous membrane.

(Retention)
In the first manufacturing method, it is necessary to hold conductive particles in the pores of the porous membrane.

  In this case, it is preferable to hold the conductive particles so that the conductive particles are not stacked in the hole depth direction. In other words, it is preferable to hold the conductive particles in the pores so that they are substantially in the same plane. This is because the accumulated conductive particles do not collapse during transfer. More preferably, it is preferable to hold the conductive particles one by one for each hole from the viewpoint of keeping the conductive particles separated from each other.

  As a method for retaining the conductive particles in the pores of the porous membrane, specifically, for example, (1) after spraying the conductive particles themselves or a dispersion thereof on the membrane surface of the porous membrane, A method in which the surface of the membrane is scraped off with a scraping means such as a brush, brush, blade, etc., and conductive particles are placed in the pores. (2) After the conductive particles themselves or a dispersion thereof are dispersed on the membrane surface of the porous membrane, A method of applying magnetic force or vibration from the outside to put conductive particles in the pores, (3) a method of immersing the porous membrane in the dispersion, (4) a constant distance from the pore-forming surface of the porous membrane Examples of the method include a method in which the plate-like members are arranged apart from each other, the dispersion liquid is introduced into the formed gap, and the porous membrane and / or the plate-like member is slid and moved.

  Since the conductive particles are physically pushed into the pores, the method (1) is preferably used from the viewpoint of easily holding the conductive particles more reliably and relatively short time required for holding. Is good. More preferably, from the viewpoint of being able to carry out by a dry method, it is preferable to use powdered conductive particles themselves in the method (1). More preferably, in the method (1), the conductive particles are attracted to the porous membrane side by a magnetic force from the side opposite to the surface to which the conductive particles are dispersed in the method (1) from the viewpoint that the conductive particles are easily introduced into the pores. It is good to scrape off by a scraping means. In this case, the conductive particles may be those having conductivity and magnetism.

(Flat membrane)
In the first manufacturing method, the flat film is a film formed substantially flat using a polymer material.

  The polymer that forms the flat film is not particularly limited, and various thermosetting resins, thermoplastic resins, rubbers, and the like can be used. Preferably, the polymer that forms a flat film from the viewpoint of easily improving the transferability of the conductive particles and being able to impart adhesion to the particle transfer film itself (particle holding film (described later) itself). It is good to have adhesiveness.

  Specific examples of the polymer forming the flat film include, for example, epoxy resins, melamine resins, phenol resins, diallyl phthalate resins, bismaleimide triazine resins, unsaturated polyester resins, polyurethane resins, Thermosetting resins such as phenoxy resin, polyamide resin, polyimide resin, polyamide resin, polyester resin, polycarbonate resin, polyphenylene oxide resin, polyurethane resin, polyacetal resin, polyvinyl acetal resin, polyethylene resin Examples include thermoplastic resins such as resins, polypropylene resins and polyvinyl resins, rubbers and elastomers containing one or more functional groups such as hydroxyl groups, carboxyl groups, vinyl groups, amino groups and epoxy groups. it can. These may be contained alone or in combination of two or more.

  The polymer forming the flat film is preferably cured by heating at the time of pressure bonding, for example, when used for an anisotropic conductive film, and a strong mechanical connection is obtained. From the viewpoint of being less susceptible to the effects of heat, it is preferable that the resin is thermosetting.

  The polymer forming the flat film preferably has an elastic modulus at 85 ° C. (before thermosetting for those that are thermoset), preferably 1 MPa or more, and more preferably 7 MPa or more. The elastic modulus at 210 ° C. (after thermosetting for those that are thermally cured) is preferably 1.5 MPa or more, and more preferably 2.5 MPa or more.

  This is because, when the elastic modulus is within the above range, the holding force of the conductive particles when the particle holding film is formed is good.

  The elastic modulus at 85 ° C. was obtained by preparing a sample (diameter 20 mm, thickness 400 μm) of the polymer and using a stress-controlled rheometer (for example, “AR500” manufactured by TA Instruments Japan Co., Ltd.). Etc.) is used to measure the elastic modulus from 20 ° C. to 180 ° C. under the measurement conditions of a temperature rising rate of 5 ° C./min, a frequency of 1 Hz, and a compression strain of 0.1%. Value.

  On the other hand, the elastic modulus at 210 ° C. is obtained by preparing a sample obtained by thermocompression bonding a sample made of the polymer (width 5 mm, length 30 mm, thickness 200 μm) at 210 ° C. and 5 MPa for 6 minutes. , Manufactured by UBM Co., Ltd., “Rheogel-E4000F” etc. is marketed.), Temperature rising rate 3 ° C./min, frequency 15 Hz, strain 0.05% (automatic adjustment), automatic static load, It is a value obtained by measuring the elastic modulus from 30 ° C. to 230 ° C. under the measurement condition of chuck interval 20 mm.

  The film thickness of the flat film is determined in consideration of the particle size of the conductive particles from the viewpoint of making it easier to hold the conductive particles in the film when obtaining the particle holding film from the obtained particle transfer film. Good.

  Specifically, for example, the upper limit of the film thickness of the flat film is preferably 3/2 or less of the particle diameter of the conductive particles, more preferably, 1 or less of the particle diameter of the conductive particles, Even more preferably, it is 2/3 times or less the particle size of the conductive particles.

  On the other hand, the lower limit of the film thickness of the flat film is preferably 1/10 or more times the particle size of the conductive particles, more preferably 1/5 or more times the particle size of the conductive particles, and even more preferably. Is preferably at least 1/3 times the particle size of the conductive particles.

  In addition, the above-mentioned flat film is prepared by applying a coating liquid prepared from the polymer material forming the above-described flat film so as to have an appropriate solid content and viscosity onto 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.

(Transcription)
In the first production method, the conductive particles are transferred onto the flat membrane surface from the porous film prepared as described above and holding the conductive particles in the pores. After the transfer, the porous membrane is separated.

  Specifically, the particle holding surface of the porous membrane holding the conductive particles in the pores may be brought into contact with the flat membrane surface.

  The transfer may be accompanied by heating and / or pressurization. Specifically, a laminating method or the like can be applied.

When heating is performed during the transfer, the heating temperature is preferably the viscosity of the polymer used for the flat film (the one to be cured is the state before curing), preferably 2 × 10 ⁴ Pa · s or less, more preferably 1.5 × 10 ⁴ Pa · s or less, and even more preferably, a temperature that is 1 × 10 ⁴ Pa · s or less is selected. This is because the conductive particles easily bite into the flat film surface and the transfer rate is improved.

  For the above viscosity, a sample (diameter 20 mm, thickness 400 μm) made of the polymer was prepared, and a stress-controlled rheometer (for example, “AR500” manufactured by TA Instruments Japan Co., Ltd.) was marketed. Is used to measure the viscosity from 20 ° C. to 180 ° C. under the measurement conditions of a heating rate of 5 ° C./min, a frequency of 1 Hz, and a compression strain of 0.1%.

  Further, when pressure is applied during the transfer, the pressure is not particularly limited. The selection may be made in consideration of the transfer rate, the film strength of the porous film and the flat film, and the like. Usually, the applied pressure is about 0.01 to 1 MPa.

  When the flat film is made of an adhesive material, the transfer can be performed without particularly heating or pressing.

  As described above, according to the first manufacturing method, as shown in FIG. 1B, the conductive particles 12 have the particle arrangement when held on the porous film 14 on the surface of the flat film 16 made of polymer. Can be obtained.

2. Second Manufacturing Method The second manufacturing method uses the particle transfer film obtained by the first manufacturing method, and embeds the transferred conductive particles 12 in the flat film 16 as illustrated in FIG. And the particle holding film 20 is manufactured.

  Here, the embedding method is not particularly limited. Any method can be applied as long as it does not easily impair the regularity of the conductive particles during transfer.

  Specifically, the embedding method includes, for example, (1) a method of pressurizing the conductive particles, and (2) heating and softening the flat film, and burying the conductive particles in the film by the weight of the conductive particles. And (3) a method of coating a transfer surface with a polymer material, and the like. These methods may be performed in combination with each other.

  The method (1) is preferable from the viewpoint of easily holding the conductive particles on the film. More preferably, in the method (1), the conductive particles may be pressurized while heating the flat film. Specifically, a laminating method or the like can be applied. In addition, the said pressurization can be performed through inclusions, such as a separator, on electroconductive particle arbitrarily.

  When the pressurization is performed, the applied pressure is not particularly limited. Selection may be made in consideration of film strength, film thickness, strength of conductive particles, and the like. Usually, it is about 0.01-1 MPa.

  When performing the said heating, the heating temperature is not specifically limited. The heating temperature varies depending on the type of polymer to be used, heat resistance, and the like, but it is preferable to select a glass transition temperature of a polymer forming a flat film from about + 20 ° C. to + 40 ° C. This is because it becomes easier to embed conductive particles in the flat film.

  The conductive particles may be entirely embedded in the flat film, or a part thereof may be exposed on the flat film surface. Further, the conductive particles may be exposed on the surface opposite to the transfer surface or may not be exposed.

  Note that the degree of embedding of the conductive particles can be varied by appropriately adjusting the pressing force, pressurizing time, heating temperature, heating time, and the like.

  As described above, according to the second manufacturing method, as shown in FIG. 2, the particle holding film 20 in which the conductive particles 12 are held in the polymer flat film 16 can be obtained.

3. Use of Particle Transfer Film and Particle Holding Film The particle transfer film and the particle holding film have conductive particles arranged in a narrow pitch in a honeycomb shape derived from the porous film as a transfer type. Moreover, the freedom degree of selection of the polymeric material which comprises both membranes is also high.

  Therefore, taking advantage of these advantages, the particle holding film manufactured from the particle transfer film can be suitably used for an anisotropic conductive film, for example.

  For example, when the particle holding film is applied to an anisotropic conductive film, when the particle holding film itself has adhesiveness, it can be used as it is as an anisotropic conductive film.

  A two-layer structure in which an adhesive layer is formed on one side of the particle holding film is preferable. Compared with a single-layer structure, it is easy to suppress the collapse of the film and the outflow of the conductive particles due to this, and to improve the conductivity in the film thickness direction when using the pressure bonding. This is because there are advantages such as.

  When the particle holding film itself does not have adhesiveness, a three-layer structure in which an adhesive layer is formed on both surfaces of the film may be used.

As the adhesive layer material, various thermosetting resins, thermoplastic resins, rubbers, and the like can be used. Specifically, for example, epoxy resin, melamine resin, phenol resin, diallyl phthalate resin, bismaleimide triazine resin, unsaturated polyester resin, polyurethane resin, phenoxy resin, polyamide resin, polyimide resin Thermosetting resins such as resins, cyanate resins, polyamide resins, polyester resins, polycarbonate resins, polyphenylene oxide resins, polyurethane resins, polyacetal resins, polyvinyl acetal resins, polyethylene resins, polypropylene resins, Examples thereof include thermoplastic resins such as polyvinyl resins, rubbers and elastomers containing one or more functional groups such as hydroxyl groups, carboxyl groups, vinyl groups, amino groups, and epoxy groups. These may be contained alone or in combination of two or more.

  The adhesive layer material preferably has an elastic modulus at 85 ° C. (before thermosetting for those that are thermoset), preferably 1 MPa or more, and more preferably 7 MPa or more. The elastic modulus at 210 ° C. (after thermosetting for those that are thermally cured) is preferably 1.5 MPa or more, and more preferably 2.5 MPa or more. Note that the elastic modulus is measured in the same manner as described above.

  This is because, if the elastic modulus is within the above range, the adhesive layer material can be easily flown out at the time of pressure bonding, and the mechanical connectivity after pressure bonding is excellent.

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

1. Production of Particle Transfer Film (Example 1T) and Particle Retaining Film (Example 1H) (Example 1)
First, a porous membrane was prepared as follows. That is, a copolymer of dodecylacrylamide and caproic acid as a surfactant in a solution in which a polycarbonate resin (manufactured by Aldrich, “polybisphenol A carbonate”) is dissolved in chloroform so as to have a concentration of 0.26 wt%. Was added at 0.026 wt% to the polyvinyl butyral resin 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, using an air pump, air having the same temperature and humidity as described above (flow rate 9 L / min) was continuously sprayed from the angle of 75 ° for 15 minutes to the coating liquid surface.

  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 made of polycarbonate resin (film thickness 5 μm) 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, a porous film having resin plating particles held in the holes was prepared as follows. That is, powder-like resin plating particles (Sekisui Chemical Co., Ltd., “Micropearl AU-204”, average) in which Ni plating layer and Au plating layer are sequentially coated on the surface of particles made of divinylbenzene-based crosslinked resin. A particle diameter of 4 μm) was sprayed on the pore-forming surface of the porous membrane.

  Next, a permanent magnet (manufactured by Seiko Sangyo Co., Ltd., ferrite magnet, 1000 gauss) installed on the side opposite to the hole forming surface is used to attract the resin plating particles to the porous film, and the surface of the film is 1 with a brush. The resin plating particles were held in the holes by scraping off once.

  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 held in the pores due to electrostatic force etc. Almost removed.

  Thereby, a porous film made of a polycarbonate resin in which the resin plating particles were held in the pores was prepared. In addition, the resin plating particles were substantially held one by one for each hole.

  Next, a resin flat film mainly composed of a polyamide resin and a phenoxy resin was prepared in the following manner. This flat film material cannot be applied to a film forming method using water droplets due to condensation.

  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.

  Then, the prepared porous film in which the resin plating particles are held in the holes and the surface of the flat film exposed by peeling the separator are overlapped, and this is formed at a temperature of 120 ° C. and a pressure of 0.1 MPa. The film was heat-laminated under the condition of a heating and pressing time of 60 seconds, cooled to room temperature, and then the porous film was removed.

  As described above, Example 1T in which the resin plating particles are transferred onto the surface of the flat resin film mainly composed of polyamide resin and phenoxy resin while maintaining the particle arrangement by the porous film having the honeycomb structure. Such a particle transfer film was obtained.

  Further, a separator (polyethylene terephthalate, thickness 38 μm, “PET38C” manufactured by Lintec Co., Ltd.) is stacked on the surface of a large number of resin plating particles of the particle transfer film according to Example 1T, and the temperature is 140 ° C. Thermal lamination was performed under the conditions of a pressure of 0.1 MPa and a heating and pressing time of 60 seconds.

  As described above, the transferred resin plating particles were embedded in a flat film and held in the film, and a particle holding film according to Example 1H was obtained. The resin plating particles were held in the film while maintaining the particle arrangement at the time of transfer. Further, a part of the film was slightly protruded from the transfer surface of the film, and the film was held in a state where the part was not exposed on the back surface of the film (the surface opposite to the transfer surface).

2. Preparation of Anisotropic Conductive Film Next, an anisotropic conductive film provided with the particle holding film according to the above example was prepared as follows.

  That is, 90 parts by weight of a dicyclopentadiene type epoxy resin (Dainippon Ink Co., Ltd., “Epicron HP7200HH”) and 10 parts by weight of nitrile rubber (NBR) (Nippon Zeon Co., Ltd., “Nipol 1072J”) 187 parts by weight of a curing agent (manufactured by Asahi Kasei Chemicals Corporation, “Novacure HXA3932HP”) was diluted with toluene so that the solid content was 42% to prepare an adhesive solution.

  Next, the above adhesive solution was applied to a release surface of a base substrate (polyethylene terephthalate, thickness 38 μm, “PET38C” manufactured by Lintec Corporation) using a comma coater.

  Subsequently, this coating layer was dried at 110 ° C. for 90 seconds to form an adhesive layer (thickness 20 μm). Then, the release surface of the separator (polyethylene terephthalate, thickness 38 μm, manufactured by Lintec Corporation, “PET38B”) was put on the surface of the adhesive layer and wound up.

  This prepared the contact bonding layer pinched between the base substrate and the separator.

  Next, the surface of the adhesive layer exposed by peeling the separator was overlapped with the surface of the produced particle holding film (particle embedding surface side), and these were bonded together.

  Thus, an anisotropic conductive film according to Example 1A having a two-layer structure in which an adhesive layer was formed on one surface of the particle holding film was obtained.

3. Evaluation of Anisotropic Conductive Film About the produced anisotropic conductive film, the conducting performance in the film thickness direction and the insulating performance in 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, Sample 1 was produced. The sample number corresponds to the number of the example.

(Evaluation of conduction performance in the film thickness direction)
About the obtained sample 1, the electrical resistance between the circuit pattern and Au bump which face each other was measured by the 4 terminal 4 probe method using the resistivity meter (the product made by Dia Instruments, "Loresta GP"). The number of samples was N = 10 [pieces], an average value was calculated by arithmetic average, and this was used as the electric resistance in the film thickness direction.

(Evaluation of insulation performance in the film surface direction)
About the obtained sample 1, the electrical resistance between adjacent circuit patterns was measured using the tester T2 (the product made by AND, "AD5522"). Note that the number of samples was N = 10 [pieces], and the ratio of the electrical resistance to 10 ⁸ Ω or more = insulation securing ratio (%) was determined.

(Evaluation results)
As a result of the evaluation, the electric resistance in the film thickness direction of Sample 1 was 1.0 (Ω). On the other hand, the insulation securing ratio of Sample 1 was 80 (%). From these results, it was confirmed that when the particle transfer film and the particle holding film according to the example were applied to an anisotropic conductive film, good anisotropic conductivity could be obtained.

  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 manufacturing method of the particle transfer film which concerns on this embodiment. It is an example of the typical sectional view of the particle retention film obtained by the manufacturing method of the particle retention film concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Porous part 12 Conductive particle 14 Porous film 16 Flat film 18 Particle transfer film 20 Particle holding film

Claims (6)

A method for producing a particle transfer film, wherein the conductive particles held in the pores of the porous film are transferred to the surface of a polymer flat film,
The method for manufacturing a particle transfer film, wherein the porous film is formed from water droplets and has a large number of pores arranged in a honeycomb shape.   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. 2. The method for producing a particle transfer film according to claim 1, wherein the particle transfer film is formed by being present in an atmosphere.   The method for producing a particle transfer film according to claim 1, wherein heating and / or pressurization is performed during the transfer. 4. The method for producing a particle transfer film according to claim 3, wherein, during the transfer, heating is performed at a temperature at which a viscosity of the polymer forming the flat film is 2 × 10 ⁴ Pa · s or less.   A method for producing a particle holding film, wherein the conductive particles of the particle transfer film according to claim 1 are embedded and held in the flat film.   An anisotropic conductive film using the particle holding film obtained by the method for producing a particle holding film according to claim 5.

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