JP2007016179A - Porous film and anisotropic electrically-conductive film given by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous film more excellent in productivity than ever, excellent in adhesion to adhesive layers, even when used for an anisotropic electrically-conductive film, and formed out of a polyamide imide, and to provide the anisotropic electrically-conductive film given by using the same. <P>SOLUTION: This porous film is formed by placing a support base plate on which a polymer solution containing at least a polyamide imide, an amphipathic substance, and an organic solvent having hydrophobicity and volatility is casted in an atmosphere having a relative humidity of not less than 50%, wherein a polymer which contains an acid component and a diisocyanate component having a hydrophobic site or a diamine component having the hydrophobic site as polymerization components is used as the polyamide imide. The hydrophobic site preferably comprises a cyclic hydrocarbon group and the polyamide imide may be copolymerized with a polyester. The anisotropic electrically-conductive film is given by filling pores of the porous film with an electrically-conductive substance and coating both surfaces of the film with the adhesive layers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a porous film and an anisotropic conductive film using the same, and more particularly to a porous film formed of polyamideimide and an anisotropic conductive film using the same.

  Conventionally, polymer porous membranes having fine pores have been used in various applications. For example, in electronic parts, etc., it is used as a base film material of an anisotropic conductive film (ACF) that exhibits conductivity in the film thickness direction and insulation in the film surface direction.

  As a method for producing a porous membrane, for example, a method in which a desired polymer is dissolved in a hydrophobic solvent and cast under a high humidity condition has recently attracted attention (for example, see Non-Patent Document 1). According to this method, water droplets condensed on the surface of the polymer solution are regularly arranged in a self-organized manner, and by using these water droplets as a template, a porous membrane having fine pores arranged in a honeycomb shape can be easily obtained. Can get to.

  By the way, in general, when a porous film is applied to an electronic component such as an anisotropic conductive film, heat resistance is often required. As a polymer excellent in heat resistance, polyimide, polyamideimide and the like are known, but these are insoluble or hardly soluble in a hydrophobic solvent.

  Therefore, in principle, it is difficult to use polyimide and polyamideimide as they are in the above-described method for producing a porous membrane, in which only a polymer soluble in a hydrophobic solvent can be used.

  Therefore, for example, in Patent Document 1, in order to obtain a porous film made of polyimide using the above-described method for producing a porous film, a polyionic complex solution of polyamic acid and a lipid, which is a precursor of polyimide, is once prepared. Then, a method is adopted in which a porous film made of polyamic acid is produced via this and then imidized.

  In addition, the present applicant has previously used a method for imparting solubility to a hydrophobic solvent by modifying a polyamideimide with a siloxane in order to obtain a porous membrane made of polyamideimide by using the above-described method for producing a porous membrane. Adopted. And the anisotropic conductive film formed by filling the pores of the obtained porous film made of siloxane-modified polyamideimide with a conductive substance and covering the adhesive layer has been developed, and a patent application has already been filed (patent) Reference 2).

Masahiro Shimomura, “Formation and functionalization of nano-mesohol structures by self-organization of polymer materials”, Functional Materials, CMC Publishing Co., Ltd., October 2003, vol. 23, no. 10, p. 18-p. 26 JP 2003-80538 A PCT / JP2005 / 006584

  However, when a porous membrane made of polyamideimide is to be produced in accordance with the technique of Patent Document 1, solvent substitution is performed many times when preparing a polymer solution, or imide is used for the obtained membrane. The manufacturing process was complicated and complicated. For this reason, there are problems such as poor productivity of the porous membrane.

  On the other hand, when the siloxane-modified polyamideimide is used, the productivity is excellent as compared with the method according to Patent Document 1.

  However, it has recently been found that the following problems arise when an anisotropic conductive film is produced using a porous film made of siloxane-modified polyamideimide.

  That is, in the above case, there is a limit to the amount of siloxane that can be introduced to the polyamideimide. For this reason, there is a limit to increasing the solubility in a hydrophobic solvent. Furthermore, if the amount of siloxane introduced is excessively increased in order to further increase the solubility in the hydrophobic solvent, the adhesion between the porous film and the adhesive layer is reduced, and blistering or peeling is likely to occur. Thus, it has been found that it may be difficult to rely on this technique too much.

  Therefore, the problem to be solved by the present invention is a porous body made of polyamideimide that is superior in productivity and has excellent adhesion to the adhesive layer even when used in an anisotropic conductive film. It is to provide a membrane. Another object is to provide an anisotropic conductive film using the same.

  In order to solve the above problems, the porous membrane according to the present invention is formed of a polyamideimide containing an acid component and a diisocyanate component having a hydrophobic site or a diamine component having a hydrophobic site as a polymerization component. The gist.

  In addition, the porous membrane according to the present invention comprises a polyamideimide containing an acid component and a diisocyanate component having a hydrophobic site or a diamine component having a hydrophobic site as a polymerization component, an amphiphile, hydrophobicity and volatilization. The gist of the invention is that it can be formed by allowing a support substrate casted with a polymer solution containing at least an organic solvent having a property to exist in an atmosphere having a relative humidity of 50% or more.

  Here, the hydrophobic part is preferably a cyclic hydrocarbon group.

  The polyamideimide is preferably copolymerized with polyester.

  The porous film preferably has a number of holes arranged in a honeycomb shape, and the inner wall surface of the holes has a hole shape that is curved outward.

  On the other hand, an anisotropic conductive film according to the present invention includes the porous film, a conductive material filled in the pores of the porous film, and an adhesive layer coated on both surfaces of the porous film. This is the gist.

  Since the polyamideimide forming the porous membrane according to the present invention contains a diisocyanate component having a hydrophobic site or a diamine component having a hydrophobic site as a polymerization component, it is dissolved in a hydrophobic solvent.

  Therefore, the porous film according to the present invention undergoes processes such as solvent replacement or imidization treatment as in the conventional case when using a method for producing a porous film utilizing the self-organization phenomenon. There is no need. Therefore, it can be manufactured with simpler and fewer processes than conventional methods, and the productivity is excellent.

  Further, when the porous film according to the present invention is used as the base film material of the anisotropic conductive film, the film and the adhesive layer are compared with the case where the porous film formed from the siloxane-modified polyamideimide is used. Excellent adhesion. Therefore, blistering and peeling are unlikely to occur.

  At this time, when the hydrophobic portion is a cyclic hydrocarbon group, the above-described effects are excellent. Moreover, when polyester is copolymerized with the polyamideimide, the heat resistance is further improved.

  On the other hand, since the anisotropic conductive film according to the present invention uses a porous film formed from the above polyamideimide, it is excellent in productivity, adhesion between the film and the adhesive layer, and excellent in heat resistance.

  Hereinafter, the porous film according to the present embodiment (hereinafter sometimes referred to as “the present porous film”) and the anisotropic conductive film according to the present embodiment using the porous film (hereinafter referred to as “the present ACF”). Will be described in detail.

1. This porous membrane This porous membrane is formed from the polyamideimide which contains an acid component and the diisocyanate component which has a hydrophobic part, or the diamine component which has a hydrophobic part as a polymerization component.

  In the polyamideimide, specific examples of the acid component include acid anhydrides, polyvalent carboxylic acids, and acid chlorides, and these may be used alone or in combination of two or more. .

  Specific examples of the acid anhydride include trimellitic acid anhydride, ethylene glycol bisanhydro trimellitate, propylene glycol bis anhydro trimellitate, 1,4 butanediol bis anhydro trimellitate, hexa Alkylene glycol bisanhydro trimellitate such as methylene glycol bisanhydro trimellitate, polyethylene glycol bis anhydro trimellitate, polypropylene glycol bis anhydro trimellitate, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, 3,3 ′, 4,4′diphenylsulfonetetracarboxylic acid anhydride, 3,3 ′, 4,4′biphenyltetracarboxylic acid anhydride, 4,4′oxydiphthalic acid anhydride, etc. Is one kind It may contain two or more kinds.

  Specific examples of the polyvalent carboxylic acid include terephthalic acid, isophthalic acid, 4,4 ′ biphenyl dicarboxylic acid, 4,4 ′ biphenyl ether dicarboxylic acid, 4,4 ′ biphenyl sulfone dicarboxylic acid, and 4,4 ′. Benzophenone dicarboxylic acid, pyromellitic acid, trimellitic acid, 3,3 ′, 4,4 ′ benzophenone tetracarboxylic acid, 3,3 ′, 4,4′biphenylsulfone tetracarboxylic acid, 3,3 ′, 4,4 ′ Biphenyltetracarboxylic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, dimer acid, stilbene dicarboxylic acid, 1,4 cyclohexane dicarboxylic acid, 1,2 cyclohexane dicarboxylic acid and the like can be exemplified, and these are one kind or Two or more kinds may be contained.

  Specific examples of the acid chloride include the acid chlorides of the above polyvalent carboxylic acids, and these may be used alone or in combination of two or more.

  Among these, preferable examples of the acid component include trimellitic acid, trimellitic acid anhydride, and cyclohexanedicarboxylic acid from the viewpoints of heat resistance and solvent solubility.

  On the other hand, in the polyamideimide, the diisocyanate component having a hydrophobic site or the diamine component having a hydrophobic site mainly functions as a component for imparting hydrophobicity to the polyamideimide and solubilizing it in a hydrophobic solvent.

  Here, as a hydrophobic site | part, specifically, a cyclic hydrocarbon group, especially the cyclic hydrocarbon group excellent in heat resistance etc. can be illustrated as a suitable thing, for example.

  When the hydrophobic site is a cyclic hydrocarbon group, the diisocyanate having a cyclic hydrocarbon group may be either a diisocyanate having an alicyclic hydrocarbon group or a diisocyanate having an aromatic hydrocarbon group. However, a combination of both may be used. Similarly, the diamine having a cyclic hydrocarbon group may be either a diamine having an alicyclic hydrocarbon group or a diamine having an aromatic hydrocarbon group, or a combination of both. .

  Preferably, from the viewpoint of solubility in a hydrophobic solvent, a diisocyanate having an alicyclic hydrocarbon group or a diamine having an alicyclic hydrocarbon group may be used alone or mainly.

  Specific examples of the diisocyanate having an alicyclic hydrocarbon group include isophorone diisocyanate, dicyclohexylmethane 4,4 ′ diisocyanate, 1,3 bis (isocyanatomethyl) cyclohexane, and the like. You may use together 1 type, or 2 or more types.

  Specific examples of the diisocyanate having an aromatic hydrocarbon group include 2,4 tolylene diisocyanate, 2,6 tolylene diisocyanate, diphenylmethane 4,4 ′ diisocyanate, 3,3′dimethyldiphenylmethane diisocyanate, 3,3. Examples include 'diethyldiphenylmethane 4,4' diisocyanate, 3,3'dichlorodiphenylmethane 4,4 'diisocyanate, 4,4' diisocyanate 3,3 'dimethylbiphenyl, p-phenylene diisocyanate, m-phenylene diisocyanate, and the like. These may be used alone or in combination of two or more.

  Of these, isophorone diisocyanate, diphenylmethane 4,4′diisocyanate, 2,4tolylene diisocyanate, and the like can be exemplified as preferable from the viewpoint of solubility in a hydrophobic solvent, heat resistance, and the like.

  Specific examples of the diamine having an alicyclic hydrocarbon group include isophorone diamine, 4,4′diaminodicyclohexyl methane, 1,3 cyclohexane bis (methylamine), and the like. May be used alone or in combination of two or more.

  Specific examples of the diamine having an aromatic hydrocarbon group include, for example, orthochloroparaphenylenediamine, p-phenylenediamine, m-phenylenediamine, 4,4′diaminodiphenyl ether, 3,4 diaminodiphenyl ether, 4,4. 'Diaminodiphenylmethane, 3,4diaminodiphenylmethane, 4,4'diaminodiphenylsulfone, 3,4'diaminodiphenylsulfone, 4,4'diaminobenzophenone, 3,4'diaminobenzophenone, 2,2'bis (aminophenyl) propane 2,4tolylenediamine, 2,6tolylenediamine, p-xylylenediamine, m-xylylenediamine and the like, and these may be used alone or in combination.

  Of these, isophoronediamine, 4,4′diaminodiphenylmethane, 2,4tolylenediamine, and the like can be exemplified as preferable from the viewpoint of solubility in a hydrophobic solvent, heat resistance, and the like.

  In addition, aliphatic dicarboxylic acids, aliphatic diamines and these diisocyanates may be contained within a range that does not adversely affect heat resistance. Specific examples of the aliphatic dicarboxylic acid include dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene), and the like. One kind or two or more kinds may be contained. Moreover, as aliphatic diamine, ethylenediamine, propylenediamine, hexamethylenediamine, etc. are mentioned, These may be contained 1 type (s) or 2 or more types.

  In the polyamideimide, the ratio of the acid component and the ratio of the diisocyanate component having a hydrophobic site or the diamine component having a hydrophobic site are not particularly limited. However, if the former is excessively large and the latter is excessively low, the solubility in a hydrophobic solvent is lowered, and it is difficult to obtain an excellent pore shape when a porous membrane manufacturing method using self-organization is used. There is a tendency to become. On the other hand, when the former is excessively small and the latter is excessively large, the heat resistance of the porous film tends to decrease. Therefore, it is good to pay attention to these when selecting the ratio of the two.

  For example, the ratio of the acid component is preferably in the range of 20 to 80 mol%, more preferably 30 to 75 mol%, and most preferably 40 to 60 mol%. On the other hand, the proportion of the diisocyanate component having a hydrophobic site or the diamine component having a hydrophobic site is preferably in the range of 80 to 20 mol%, more preferably 70 to 25 mol%, most preferably 60 to 40 mol%. Good to be.

  It is because it is excellent in the balance of the solubility with respect to a hydrophobic solvent, heat resistance, etc. if it exists in these ranges.

  The polyamideimide may be copolymerized with a polymer having a polarity lower than that of an amide bond or imide bond for the purpose of improving the heat resistance of the porous membrane. In this case, the copolymerization may be random or block, and is not particularly limited. In addition, in this application, what copolymerized another polymer with the polyamideimide is also contained in the concept of a polyamideimide.

  Specific examples of the other polymer include polyester, polyether, polysulfone, polyamide, polyurethane and the like, and these may be used alone or in combination of two or more.

  Among these, from the viewpoint of easily improving the heat resistance of the porous membrane, polyester and the like can be exemplified as suitable ones.

  Specific examples of the polyester include, but are not particularly limited to, polycaprolactone, polymerized from dicarboxylic acid and diol, and the like.

  Specific examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6 naphthalene dicarboxylic acid, 4,4 ′ biphenyl dicarboxylic acid, 4,4 ′ biphenyl ether dicarboxylic acid, and 4,4 ′. Aromatic dicarboxylic acids such as benzophenone dicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, maleic acid, fumaric acid, dimer acid, aliphatic dicarboxylic acid such as dodecanedicarboxylic acid, azelaic acid, 1,2 cyclohexane dicarboxylic acid Examples thereof include alicyclic dicarboxylic acids such as 1,3 cyclohexanedicarboxylic acid and 1,4 cyclohexanedicarboxylic acid, and these may be used alone or in combination of two or more.

  On the other hand, as the diol, specifically, for example, ethylene glycol, propylene glycol, neopentyl glycol, 1,4 butanediol, 1,5 pentanediol, 1,6 hexanediol, 1,9 nonanediol, 1, Examples include 10-decanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tetramethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and other alkylene glycols. These may be used alone or in combination of two or more.

  When the polyamideimide is optionally copolymerized with another polymer, the proportion of the other polymer is preferably 70% by weight or less, more preferably 55% by weight or less, and most preferably 30% by weight or less. And good.

  In this case, the ratio of the acid component in the polyamideimide is preferably in the range of 30 to 98 mol%, more preferably 40 to 95 mol%, and most preferably 55 to 85 mol%. On the other hand, the ratio of the diisocyanate component having a hydrophobic site or the diamine component having a hydrophobic site is preferably in the range of 70 to 2 mol%, more preferably 60 to 5 mol%, most preferably 45 to 15 mol%. Good to be.

  It is because it is excellent in the balance of the solubility with respect to a hydrophobic solvent, heat resistance, etc. if it exists in these ranges.

  In addition, additives such as an epoxy prepolymer, a curing agent, and a sensitizer may be added to the polyamideimide within a range that does not impair the solubility in a hydrophobic solvent. When these are added, the present porous film can be heat-cured and photocured under the condition that the structure of the film does not collapse, so that the film strength and the like can be improved.

  Polymerization of the polyamide imide is carried out, for example, by using a method such as an isocyanate method or an acid chloride method from the acid component and the diisocyanate (diamine) component, optionally in the presence of a catalyst in a polar solvent such as an amide solvent. Just do it. In addition, when copolymerizing another polymer with polyamideimide, a solution polymerization method, a melt polymerization method, a method combining these, or the like can be used. For example, a method of polymerizing a solution obtained by polymerizing polyamideimide with another polymer previously melt-polymerized can be exemplified.

  In this porous membrane, the pore shape (three-dimensional shape of the hole, whether the hole penetrates in the film thickness direction, the arrangement of the holes, etc.), the size of the hole diameter, the film thickness, etc. are not particularly limited. And can be adjusted appropriately according to the application.

  For example, when this porous film is used as a base film material for an anisotropic conductive film, the pore form of the porous film has a large number of holes that penetrate in the film thickness direction. For example, the inner wall surface of the hole portion may be exemplified by a hole shape that is curved outward.

  An example of the hole shape will be described more specifically with reference to the drawings. As shown in FIG. 1A, the porous film 10 has a large number of holes 12 penetrating in the film thickness direction. The inner wall surfaces 14 of these holes 12 are curved in a substantially spherical shape toward the outer side. Further, as shown in FIG. 1B, these hole portions 12 are arranged in a honeycomb shape, and the adjacent hole portions 12 are separated from each other by a partition wall 16. Further, the partition wall 16 has a narrow constricted portion 16a in the vicinity where the inner wall surfaces 14 of the adjacent hole portions 12 are most adjacent to each other.

  In this case, with respect to the diameter and interval of the hole, the width and interval of a plurality of conductors (for example, protruding electrodes, wiring patterns, etc.) of the connected object (for example, IC chip, flexible printed wiring board: FPC, etc.) It may be determined in consideration.

  However, from the viewpoint of ensuring insulation in the film surface direction and obtaining high connection reliability, the diameter of the hole is smaller than the narrowest of the intervals between the plurality of conductors of the connected object. And it is desirable that the interval between the holes is smaller than the narrowest of the widths of the plurality of conductors of the connected object.

  Preferably, the diameter of the hole is ½ or less of the narrowest of the intervals between the plurality of conductors of the connected object, and the interval of the hole is the width of the plurality of conductors of the connected object It is good to make it 1/2 or less of the narrowest.

  In addition, as shown in FIG.1 (b), the diameter of a hole means the value which measured and averaged the diameter R of the opening part of the hole which appears on the film | membrane surface or a back surface. On the other hand, the interval between the hole portions means a value obtained by measuring and averaging the distance L between the opening portion of the hole portion appearing on the film surface or the back surface and the opening portion of the adjacent hole portion. The diameter R and the distance L can be measured by an electron micrograph, an optical micrograph, etc. on the surface of the porous membrane.

  The film thickness may be determined in consideration of the mechanical strength, voltage resistance, etc. of the anisotropic conductive film. Generally, examples of preferable upper limit values include 100 μm and 50 μm, and examples of preferable lower limit values that can be combined with these preferable upper limit values include 1 μm and 5 μm.

  In order to produce a porous membrane made of the polyamideimide having such a honeycomb structure, a polymer solution containing at least the polyamideimide, an amphiphile, and an organic solvent having hydrophobicity and volatility It is preferable to use a method in which a support substrate in which is cast is present in a high humidity atmosphere. When this method is used, a porous film having the above pore shape is spontaneously formed on the basis of the following principle.

  That is, the polymer solution cast on the support substrate with a predetermined concentration and a predetermined coating thickness is deprived of latent heat when the organic solvent 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 water droplet group evaporates, a porous film having a large number of pores arranged in a honeycomb shape is formed using the water droplet group as a template.

  In the polymer solution, examples of the polyamideimide include those described above, and these may be used alone or in combination.

  In the polymer solution, the amphiphilic substance is a so-called surfactant, which is a compound having both a hydrophobic part and a hydrophilic part. This amphiphilic substance is added mainly for the purpose of stabilizing the water droplet group adhering to the surface of the polymer solution.

  As such an amphiphilic substance, specifically, for example, a polymer having a hydrophilic acrylamide polymer as a main chain skeleton, a dodecyl group as a hydrophobic side chain, and a lactose group or a carboxyl group as a hydrophilic side chain. Or, a polyionic complex of an anionic polysaccharide such as heparin or dextran sulfate and a quaternary long-chain alkylammonium salt can be exemplified. These may be used alone or in combination.

  Specific examples of the organic solvent having hydrophobicity and volatility in the polymer solution include, for example, halides such as chloroform and methylene chloride, aromatic hydrocarbons such as benzene, toluene and xylene, ethyl acetate and acetic acid. Examples thereof include esters such as butyl, ketones such as methyl ethyl ketone (MEK) and acetone. These may be used alone or in combination.

  At this time, the concentration of the polyamideimide contained in the polymer solution can be exemplified by 50% by weight, 10% by weight, etc. as a preferred upper limit, and as a preferred lower limit that can be combined with these preferred upper limits, Examples thereof include 0.05% by weight and 0.1% by weight.

  Moreover, as a ratio of the amphipathic substance contained in the polymer solution, it is possible to exemplify 20% by weight, 10% by weight, etc. as preferable upper limit values for the polyamideimide, and these preferred upper limit values can be combined. Examples of preferable lower limit values include 0.01% by weight and 0.05% by weight.

  Further, as the material of the support substrate for casting the polymer solution, specifically, for example, inorganic materials such as glass, metal, silicon wafer, polymer materials such as polypropylene, polyethylene, polyetherketone, fluororesin, Examples thereof include water and liquid paraffin.

  Examples of the coating thickness when casting the polymer solution on a support substrate include 3500 μm and 2000 μm as preferable upper limit values, and 50 μm and 150 μm as preferable lower limit values that can be combined with these preferable upper limit values. Etc. can be illustrated.

  Moreover, it is desirable that the support substrate cast with the polymer solution be present in a high humidity atmosphere with a relative humidity of 50% to 95%. This is because if the relative humidity is less than 50%, condensation tends to be insufficient, and if it exceeds 95%, it tends to be difficult to control the environment.

  In this method, the polymer solution may be cast on a support substrate in a high humidity atmosphere, or the support substrate on which the polymer solution is cast in advance may be placed in a high humidity atmosphere. Alternatively, a gas humidified at high humidity may be blown onto the polymer solution. In addition, the gas in the said atmosphere and the gas for spraying are not specifically limited. Specific examples of these gases include air, inert gases such as nitrogen gas and argon gas, and mixed gases thereof. Preferably, air that is advantageous in terms of cost is used.

  Further, in order to promote the evaporation of the organic solvent and the evaporation of the water droplet group, heating and drying may be performed during the formation of the porous film within a range that does not affect the film formation.

  Further, the porous membrane thus obtained may be further heated to near the glass transition temperature of polyamideimide.

  According to the principle described above, the partition located between the adjacent holes is formed by the polymer solution that has entered the gap between the adjacent water droplets. Therefore, especially in the vicinity of the constricted portion where the water droplets and water droplets are closest to each other, there is a tendency that the partition wall becomes thin.

  However, when the film is formed and heated to near the glass transition temperature of polyamideimide, the thinned constriction part softens and melts quickly, and the constriction part becomes thicker or may exist in the constriction part. The hole is crushed.

  Thereby, the independence between each adjacent hole part increases, and it can be set as the porous film excellent in the independence of a hole part. Therefore, when this is used for an anisotropic conductive film, for example, the insulation property in the film surface direction of the obtained anisotropic conductive film can be improved.

  Moreover, in the said heating, you may further pressurize arbitrarily in a film thickness direction.

  According to the principle described above, water droplets condensed on the surface of the polymer solution are concentrated in a floating island shape. When the water droplet groups densely packed in a floating island shape are transported and accumulated, a step or unevenness in the film thickness direction tends to occur near the boundary where the water droplet groups collide with each other. However, when heating and pressurization are further performed after the film formation, the level difference or unevenness generated on the film surface is made uniform.

  Thereby, it can be set as the porous film excellent in the smoothness of the surface. Therefore, when this is used for an anisotropic conductive film, for example, it is easy to uniformly fill the hole with a conductive substance, and the conductivity of the obtained anisotropic conductive film in the film thickness direction can be improved. it can.

2. This ACF
As illustrated in FIG. 2, the ACF 20 includes the porous film 10 described above, a conductive material 22 filled in the pores 12, and an adhesive layer 24 coated on both surfaces of the film 10. ing.

  Here, the conductive substance is preferably composed of a group of conductive particles from the viewpoint of being easily filled into minute holes and being excellent in conduction in the film thickness direction. In this case, the average diameter of the conductive particles may be determined according to the hole diameter of the hole. As an average diameter of electroconductive particle, about 1 micrometer or less can be illustrated in general.

  Specific examples of the conductive particles include metal particles, resin plating particles, and carbon particles. These may be used alone or in combination.

  Among these conductive particles, metal particles can be preferably used. This is because the electric resistance is small and the melting point of the metal is lowered by reducing the diameter of the particles, so that it is easy to perform heat fusion at a low temperature.

  Specific examples of the metal particles include Ag particles, Au particles, Pt particles, Ni particles, Cu particles, and Pd particles. These may be used alone or in combination. Since these metal particles are excellent in electric conductivity, there is an advantage that conduction in the film thickness direction is easily obtained. Among these metal particles, particularly, Ag particles can be preferably used.

  In the case where the conductive particles are metal particles, resin plating particles, or the like, at least the particle surface is made of metal, the group of these particles filled in the holes is preferably fused and integrated in the holes. . This is because the gap between the particles is reduced, the contact resistance is reduced, and the electric resistance in the film thickness direction can be reduced. Moreover, since the organic substance etc. which exist between these particles are removed by heating, the electrical resistance in the film thickness direction can also be reduced by this.

  In the present ACF, all the pores of the porous membrane may be filled with a conductive substance, or a part of the hole is not filled with a conductive substance. May be. That is, it is only necessary that at least one of the holes facing the conductor of the connected object is filled with a conductive substance.

  The method of filling the conductive material can be appropriately selected in consideration of the type and properties of the conductive material.

  As a specific method of filling the conductive material, for example, a dispersion solution in which the conductive material is dispersed in a solvent in which the polyamideimide forming the porous film is insoluble is used. A method of immersing the porous membrane, (2) a method of dripping or coating the dispersion solution on the surface of the porous membrane, and (3) a distance from the surface of the porous membrane placed on the substrate by a certain distance. An example is a method in which another substrate is placed, the dispersion solution is introduced into the gap between the porous membrane and the other substrate, and one or both of the substrates are slid in the film surface direction. it can.

  Here, in the dispersion solution, examples of the solvent include alcohol solvents such as ethanol, water, ester solvents, amide solvents, hydrocarbon solvents, ketone solvents, ether solvents, and the like. These may be used alone or in combination.

  At this time, when a hydrophilic solvent is used, it is preferable that the surface of the porous membrane is subjected to a hydrophilic treatment in advance. This is because the wettability between the present porous membrane and the solvent is improved, and the dispersion solution is easily penetrated into the pores, so that the conductive material is easily uniformly filled in the pores.

  Specific examples of the hydrophilic treatment include ultraviolet irradiation, corona treatment, and plasma treatment.

  Further, in the dispersion solution, the content of the conductive substance can be exemplified by 30% by weight, 20% by weight, 10% by weight, 5% by weight, etc. as a preferable upper limit value, which can be combined with these preferable upper limit values. Examples of preferable lower limit values include 0.1% by weight, 0.5% by weight, and 1% by weight.

  Of the above-described methods for filling the conductive material, the method (3) can be preferably used from the viewpoint that the conductive material can be selectively filled into the hole. Hereinafter, this method will be described.

  According to this filling method, when the substrate is moved slowly in the film surface direction, the conductive material slips on the surface of the porous film due to the surface tension of the solvent. Then, when the interface of the dispersion solution passes over the pores, the penetration of the dispersion solution into the pores due to capillary action and the evaporation of the solvent in the pores are repeated, and the conductive substance is gradually formed in the pores. It will be filled. As a result, the conductive material is selectively filled into the pores of the porous membrane.

  In this filling method, both substrates can be used without particular limitation as long as they have flat and smooth surfaces. Specific examples of the substrate include inorganic materials such as glass, ceramics, and metals, organic materials such as polymers, and composite materials obtained by combining these materials.

  Further, the distance between the surface of the present porous membrane and another substrate may be within a range in which the dispersion solution can be held by the surface tension of the solvent of the dispersion solution introduced into the gap.

  In general, if the distance between the two is too close, the amount of the dispersion solution that can be introduced into the gap is reduced, so that the amount of the conductive material filled in the pores tends to be reduced. On the other hand, if the distance between the two is excessively large, the dispersion solution cannot be held between the surface of the porous membrane and the substrate, and it tends to be difficult to slide the substrate itself. Therefore, the distance between the surface of the porous membrane and the substrate may be set in consideration of these.

  Moreover, when using this filling method, water can be used suitably as a solvent of the dispersion solution mentioned above. This is because the surface tension is large and there is an advantage that the conductive substance can be easily moved on the film surface.

  The movement speed of both substrates is basically determined in consideration of the solvent type of the dispersion solution, the surface tension of the solvent, the concentration of the dispersion solution, etc., and the penetration of the dispersion solution into the pores and the solvent in the pores. An optimal speed may be selected as appropriate so that evaporation occurs in a well-balanced manner.

  At this time, when the moving speed is excessively high, the amount of the conductive material filled in the hole portion is reduced, or the conductive material tends to be filled unevenly. On the other hand, when the moving speed is excessively slow, the solvent in the dispersion solution evaporates, the concentration of the dispersion solution becomes too high, and the conductive material tends to adhere to the surface of the porous membrane. Therefore, it is preferable to select the moving speed in consideration of these.

  Preferably, the moving speed is preferably constant from the viewpoint of more uniformly filling the hole with the conductive material. Specific examples of the moving speed include 1 to 15 μm / sec.

  In addition, in this filling method, the temperature of the environmental atmosphere is increased or the porous membrane is heated within a range that does not affect the amount of the conductive material filled in the hole. The evaporation of the solvent of the dispersed solution that has penetrated into the solution may be promoted. When these are performed, filling of the conductive material into the hole is promoted, so that the moving speed can be increased. For this reason, the production capacity of the anisotropic conductive film can be variously adjusted.

  In this way, the adhesive layer is coated on both surfaces of the porous membrane in which the pores are filled with the conductive material. As the adhesive layer forming material, any material can be used as long as it has adhesiveness and insulating properties with respect to the connected object. Specifically, for example, a prepreg in which a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, a bismaleimide resin, or a cyanate resin is in a semi-cured state can be exemplified.

  In the case where the adhesive layer is a prepreg, the adhesive layer is likely to flow away from the gap between the conductors of the connected object, and the adhesiveness with the connected part is increased, so that high connection reliability can be easily ensured.

  As said thermosetting resin, an epoxy-type resin can be used suitably from a viewpoint of being excellent in adhesiveness with a to-be-connected part.

  In addition, the thickness of the adhesive layer may be set as appropriate in consideration of the height of the conductor of the connected object, the distance between the conductors, and the like. In general, if the thickness of the adhesive layer is too thin, the mechanical strength after thermocompression tends to be low. On the other hand, when the thickness of the adhesive layer is excessively large, there is a tendency that the adhesive layer is less likely to be fluidly eliminated during thermocompression bonding. Therefore, the thickness of the adhesive layer is preferably selected in consideration of these.

  Examples of the thickness of the adhesive layer include 100 μm and 50 μm as preferable upper limit values, and examples of preferable lower limit values that can be combined with these preferable upper limit values include 0.1 μm and 1 μm.

  Specific methods for coating the adhesive layer include a method of applying an adhesive layer forming material using a known coating means such as a coater, and a method of laminating a film-like adhesive layer prepared in advance. It is done.

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

1. Preparation of polyamideimide for porous membrane according to Example (Preparation of polyamideimide for porous membrane according to Example 1)
76.6 g of trimellitic anhydride as the acid component, 204.5 g of isophorone diisocyanate as the alicyclic diisocyanate component, 1 g of potassium fluoride as the catalyst, together with 1,3 dimethyl 2-imidazolidinone (polar solvent) and a polymer concentration of 50 After being charged in a reaction vessel so as to be wt% (solvent is N-methyl-2-pyrrolidone: NMP), the temperature was raised to 180 ° C. and the reaction was carried out for 1 hour.

  Next, the obtained polymer solution (polymer weight average molecular weight Mw = 82000) was diluted with cooling so that the polymer concentration became 20% by weight, and this was poured into stirring water, precipitated and dried.

  As a result, a polyamideimide containing 30 mol of trimellitic anhydride and 70 mol of isophorone diisocyanate as polymerization components was obtained. Hereinafter, this is referred to as polyamideimide for Example 1.

(Preparation of polyamideimide for porous membrane according to Example 2)
Except for 103.4 g of trimellitic anhydride and 177.7 g of isophorone diisocyanate, 40 mol of trimellitic anhydride and 60 mol of isophorone diisocyanate are included as polymerization components in the same manner as in the production of polyamideimide for Example 1. Polyamideimide was obtained. Hereinafter, this is referred to as polyamideimide for Example 2. In addition, it was the weight average molecular weight Mw = 78000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 3)
Except for 131.0 g of trimellitic anhydride and 150.1 g of isophorone diisocyanate, 50 mol of trimellitic anhydride and 50 mol of isophorone diisocyanate are included as polymerization components in the same manner as in the production of polyamideimide for Example 1. Polyamideimide was obtained. Hereinafter, this is referred to as polyamideimide for Example 3. In addition, it was the weight average molecular weight Mw = 80000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 4)
Except for 159.4 g of trimellitic anhydride and 121.7 g of isophorone diisocyanate, 60 mol of trimellitic anhydride and 40 mol of isophorone diisocyanate are included as polymerization components in the same manner as in the production of polyamideimide for Example 1. Polyamideimide was obtained. Hereinafter, this is referred to as polyamideimide for Example 4. In addition, it was the weight average molecular weight Mw = 75000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 5)
Except for 203.4 g of trimellitic anhydride and 77.7 g of isophorone diisocyanate, 60 mol of trimellitic anhydride and 40 mol of isophorone diisocyanate are included as polymerization components in the same manner as in the production of polyamideimide for Example 1. A polyamideimide was obtained. Hereinafter, this is referred to as polyamideimide for Example 5. In addition, it was the weight average molecular weight Mw = 72000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 6)
87.9 g trimellitic anhydride as acid component, 117.1 g isophorone diisocyanate as alicyclic diisocyanate component, 1 g potassium fluoride as catalyst, 1,3 dimethyl 2-imidazolidinone (polar solvent) and polymer concentration 50 After being charged into the reaction vessel so as to be wt% (solvent NMP), the temperature was raised to 180 ° C. and the reaction was carried out for 1 hour.

  Furthermore, 133.3 g of poly-ε-caprolactone (weight average molecular weight Mw = 10000) was added to the reaction vessel, and the reaction was continued for 3 hours.

  Next, the obtained polymer solution (polymer weight average molecular weight Mw = 48000) was diluted with cooling so that the polymer concentration became 20% by weight, and this was poured into stirring water, precipitated and dried.

  As a result, a polyamideimide in which 33% by weight of polycaprolactone (a type of polyester, hereinafter omitted) was copolymerized with a polyamideimide containing 53 mol of trimellitic anhydride and 47 mol of isophorone diisocyanate as polymerization components was obtained. Hereinafter, this is referred to as polyamideimide for Example 6.

(Preparation of polyamideimide for porous membrane according to Example 7)
In the same manner as in the preparation of polyamideimide for Example 6, except that 96.3 g of trimellitic anhydride, 51.5 g of isophorone diisocyanate, and 133.3 g of poly-ε-caprolactone, Polyamideimide obtained by copolymerizing 54% by weight of polycaprolactone with polyamideimide containing 32 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 7. In addition, it was the weight average molecular weight Mw = 53000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 8)
Trimellitic anhydride 57mol, similar to the production of polyamideimide for Example 6, except that 116.4g trimellitic anhydride, 99.9g isophorone diisocyanate, 64.8g poly-ε-caprolactone, A polyamideimide obtained by copolymerizing 28% by weight of polycaprolactone with a polyamideimide containing 43 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 8. In addition, it was the weight average molecular weight Mw = 48000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 9)
Except for 125.8 g of trimellitic anhydride, 43.2 g of isophorone diisocyanate, and 112.0 g of poly-ε-caprolactone, 77 mol of trimellitic anhydride, A polyamideimide in which 47% by weight of polycaprolactone was copolymerized with a polyamideimide containing 23 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 9. In addition, it was the weight average molecular weight Mw = 45000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 10)
Except for the trimellitic anhydride 144.7 g, isophorone diisocyanate 82.7 g, and poly-ε-caprolactone 53.8 g, in the same manner as in the preparation of the polyamideimide for Example 6, 67 mol trimellitic anhydride, Polyamideimide obtained by copolymerizing 24% by weight of polycaprolactone with polyamideimide containing 33 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 10. In addition, it was the weight average molecular weight Mw = 56000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 11)
Trimellitic anhydride 83mol, similar to the production of polyamideimide for Example 6, except that 154.2g of trimellitic anhydride, 35.4g of isophorone diisocyanate, 91.5g of poly-ε-caprolactone, A polyamideimide obtained by copolymerizing 39% by weight of polycaprolactone with a polyamideimide containing 17 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 11. In addition, it was the weight average molecular weight Mw = 52000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 12)
75 mol trimellitic anhydride, in the same manner as in the production of polyamideimide for Example 6, except that 172.5 g trimellitic anhydride, 65.9 g isophorone diisocyanate, and 42.7 g poly-ε-caprolactone, A polyamideimide in which 19% by weight of polycaprolactone was copolymerized with a polyamideimide containing 25 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 12. In addition, it was the weight average molecular weight Mw = 58000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 13)
Except for 181.5 g of trimellitic anhydride, 27.7 g of isophorone diisocyanate, and 71.8 g of poly-ε-caprolactone, in the same manner as in the preparation of polyamideimide for Example 6, 88 mol of trimellitic anhydride, A polyamideimide obtained by copolymerizing 24% by weight of polycaprolactone with a polyamideimide containing 12 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 13. In addition, it was the weight average molecular weight Mw = 47000 of the polymer of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 14)
Except for 213.8 g of trimellitic anhydride, 40.7 g of isophorone diisocyanate, and 26.6 g of poly-ε-caprolactone, in the same manner as the production of polyamideimide for Example 6, 86 mol of trimellitic anhydride, A polyamideimide obtained by copolymerizing 12% by weight of polycaprolactone with a polyamideimide containing 14 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 14. In addition, it was the polymer weight average molecular weight Mw = 46000 of the polymer solution obtained in the middle of manufacture.

(Preparation of polyamideimide for porous membrane according to Example 15)
94 mol trimellitic anhydride, similar to the production of polyamideimide for Example 6, except that 220.5 g trimellitic anhydride, 17.0 g isophorone diisocyanate, 43.6 g poly-ε-caprolactone, A polyamideimide obtained by copolymerizing 20% by weight of polycaprolactone with a polyamideimide containing 6 mol of isophorone diisocyanate as a polymerization component was obtained. Hereinafter, this is referred to as polyamideimide for Example 15. In addition, it was the weight average molecular weight Mw = 42000 of the polymer of the polymer solution obtained in the middle of manufacture.

2. Preparation of siloxane-modified polyamideimide for porous membrane according to Comparative Example 1 220.5 g of trimellitic anhydride, 17.0 g of diphenylmethane diisocyanate, 1 g of potassium fluoride, 1,3 dimethyl 2-imidazolidinone (polar solvent) At the same time, the reaction vessel was charged with a polymer concentration of 50% by weight (using a solvent NMP), and then heated to 180 ° C. and reacted for 1 hour.

  Further, 43.6 g of 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane was added to the reaction vessel, and the reaction was continued for 3 hours.

  Next, the obtained polymer solution (polymer weight average molecular weight Mw = 32000) was diluted with cooling so that the polymer concentration became 20% by weight, and this was poured into stirring water, precipitated and dried. As a result, a siloxane-modified polyamideimide for Comparative Example 1 was obtained.

3. Preparation of polyionic complex solution for porous membrane according to Comparative Example 2 120.2 g (0.6 mol) of 3,4'-diaminodiphenyl ether, 74.7 g (0.45 mol) of isophthalic acid, 135 g of pyridine (1.71 mol) , A mixed solution of 279 g (0.9 mol) of triphenyl phosphite, 15.3 g (0.36 mol) of lithium chloride and 44.1 g (0.4 mol) of calcium chloride in 5 liters of N-methyl-2-pyrrolidone at 100 ° C. Stir for 4 hours. After allowing to cool, the polymer solution was poured into 5 liters of methanol, stirred at room temperature for 1 hour, the precipitated solid was filtered off, and the filtrate was washed with methanol and dried.

  Subsequently, the obtained solid substance was added to a solution of 656 g (2.05 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride in 5.4 liters of N-methyl-2-pyrrolidone under ice cooling. Added. After the addition, the mixture was reacted for 1 hour under a nitrogen atmosphere and ice-cooling, and at room temperature for 4 hours to obtain a polyamic acid solution.

  This polyamic acid solution was slowly poured into ethyl acetate to cause reprecipitation, followed by filtration and drying to obtain a polyamic acid powder. 100 mg of this polyamic acid was dissolved in water at pH 8 by heating.

  Meanwhile, 200 mg of dimethyl dioctadecyl ammonium bromide was dispersed in 200 mL of water by applying ultrasonic waves. The above two liquids were mixed, and the temperature was returned to room temperature and stirred overnight. Thereafter, chloroform was added, and the chloroform phase was separated with a separatory funnel. Chloroform was concentrated with an evaporator and reprecipitated with acetone. Centrifugation was performed at 2600 rpm for 30 minutes using a centrifuge, and the solvent was dried. As a result, a polyionic complex solution was obtained.

4). Production of porous films according to Examples and Comparative Examples (Production of porous films according to Examples 1 to 15 and Comparative Example 1)
To a solution obtained by dissolving the polyamideimide for Example 1 in chloroform at a concentration of 0.2% by weight, a copolymer of dodecylacrylamide and caproic acid as an amphiphile was added at 10% by weight with respect to the polyamideimide. A polymer solution was prepared.

  Next, this polymer solution was cast at a coating film thickness of 1560 μm onto a petri dish (φ90 mm) continuously sprayed with air having a relative humidity of 70% at a flow rate of 2 L / min to volatilize chloroform. As a result, a porous membrane made of polyamideimide having a large number of pores penetrating in the film thickness direction, the pores being arranged in a honeycomb shape, and the inner wall surface of the pores being curved outwardly ( A film thickness of 4 μm) was obtained. Hereinafter, this is referred to as a porous film according to Example 1.

  Moreover, it has many hole parts penetrated in the film thickness direction like the preparation procedure of the porous film which concerns on Example 1 except having used the polyamideimide for Examples 2-15, and a hole part is a honeycomb. A porous membrane (each film thickness: 4 μm) made of each polyamideimide was prepared, in which the inner wall surfaces of the holes were curved outwardly. Hereinafter, these are referred to as porous membranes according to Examples 2 to 15.

  3 and 4 show electron micrographs of the porous films according to Examples 3 and 5 as examples of the obtained porous film.

  Moreover, it had many holes penetrated in the film thickness direction in the same manner as the porous film production procedure according to Example 1 except that the siloxane-modified polyamideimide for Comparative Example 1 was used. A porous film (film thickness: 4 μm) made of siloxane-modified polyamideimide was prepared, in which the inner wall surfaces of the holes were curved outwardly. Hereinafter, this is referred to as a porous film according to Comparative Example 1.

(Preparation of porous membrane according to Comparative Example 2)
The prepared polyionic complex solution was diluted to prepare a 0.2 wt% chloroform solution. This solution was cast at a coating film thickness of 1560 μm on a petri dish (φ90 mm) in which air having a relative humidity of 70% was continuously blown at a flow rate of 2 L / min to volatilize chloroform. As a result, a precursor film made of a polyionic complex has a large number of holes penetrating in the film thickness direction, the holes are arranged in a honeycomb shape, and the inner wall surfaces of the holes are curved outward. was gotten. This precursor film is immersed in a solution of benzene: acetic anhydride: pyridine = 3: 1: 1 overnight, and a polyionic complex is imidized to produce a porous film (film thickness: 4 μm) made of polyamideimide. did. The lipid was removed by rinsing with ethanol.

5. Production of Anisotropic Conductive Film According to Examples and Comparative Examples The porous film according to Example 1 is placed on a tetrafluoroethylene-hexafluoropropylene copolymer film (hereinafter referred to as “FEP film”). Then, the surface of the porous membrane was irradiated with UV light (258 nm) for 10 minutes using a UV irradiator (manufactured by Sen Special Light Source Co., Ltd.), and the membrane surface was subjected to a hydrophilic treatment.

  Next, a glass substrate is arranged at a certain distance from the porous membrane fixed on the FEP film, and an Ag aqueous dispersion (Nippon Paint) having a concentration of 3% by weight is placed in the gap between the porous membrane and another glass substrate. “Fine Sphere SVW102” having an average particle size of 50 nm) was injected, and the Ag aqueous dispersion was held by the surface tension in the gap between the porous membrane and the other glass substrate.

  Next, the glass substrate was slid at a constant speed (5 to 10 μm / sec), and the glass substrate was pulled away. As a result, a porous membrane was obtained in which the pores were selectively filled with Ag particles. The Ag particles filled in the pores were thermally fused by heating at 150 ° C. for 3 minutes.

  Next, a bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin, “Epicoat 1001”), NBR (manufactured by Nippon Zeon, “Nipol 1072J”), and an imidazole curing agent (manufactured by Shikoku Kasei, “Curesol C11Z”) are combined with bisphenol. A-type epoxy resin: NBR: imidazole curing agent = 40: 50: 5 In a weight ratio of 40: 50: 5, dissolved in a mixed solvent of MEK / THF = 50/50 so that the solid content is 30% by weight. And dried for 10 minutes to prepare an adhesive layer.

  Next, after laminating this adhesive layer on the surface of the porous membrane in which Ag particles are selectively filled in the pores under the conditions of 23 ° C. ± 2 ° C. and 1 MPa, the FEP film is peeled off from the back surface of the porous membrane did. Next, an adhesive layer was laminated on the back surface of the porous film under the same conditions. Thereby, an anisotropic conductive film according to Example 1 was produced.

  Except for using the porous film according to Examples 2 to 15 and the porous film according to Comparative Examples 1 to 2, Examples 2 to 15 were carried out in the same manner as in the procedure for producing the anisotropic conductive film according to Example 1. The anisotropic conductive film which concerns on this, and the anisotropic conductive film which concerns on Comparative Examples 1-2 were produced.

6). Evaluation of porous films and anisotropic conductive films according to examples and comparative examples Evaluation of porous films and anisotropic conductive films according to examples and comparative examples was performed as follows.

(The heat resistance of the polymer that forms the porous membrane)
About the polymer which forms each porous film, dynamic viscoelasticity measurement (measuring conditions: strain 0.1%, frequency 15Hz, using a dynamic viscoelasticity measuring device ("Rheogel-E4000F" manufactured by UBM)) The glass transition temperature Tg of the polymer was measured at a temperature of −50 ° C. to 300 ° C. and a heating rate of 3 ° C./min. A polymer having a glass transition temperature Tg of 130 ° C. or higher was evaluated as a pass “◯”, and a polymer having a glass transition temperature Tg of less than 130 ° C. was evaluated as a reject “X”. Further, among the samples that were passed “◯”, those in which the glass transition temperature Tg of the polymer was within the range of 130 ° C. or higher and lower than 150 ° C. were set as “Δ”.

(Porosity state of porous membrane)
The surface of each porous membrane was observed with an optical microscope at a magnification of 3000 times, and a case where less than 5 holes collapsed in a field of view of 0.075 mm × 0.1 mm was evaluated as a pass “◯”. The case where there were more than one was evaluated as a failure “x”. In addition, among those that passed “◯”, those that showed a relatively large number of hole collapses were marked “△”.

(Number of porous membrane formation steps)
Each porous membrane forming process is relatively few, and those that are within the allowable range for actual production are evaluated as “good”, and those that have relatively many forming processes that exceed the allowable range for actual production are rejected. Evaluated as “x”.

(Anisotropic conductivity of anisotropic conductive film)
Each anisotropic conductive film was evaluated for anisotropic conductivity by evaluating the conduction performance in the film thickness direction and the insulation performance in the film surface direction.

(1) Evaluation of conduction performance in the film thickness direction Evaluation of conduction performance in the film thickness direction was performed as follows. That is, one surface of each anisotropic conductive film was temporarily press-bonded to a comb-shaped electrode having a pitch of 30 μm (comb-like electrodes in which adjacent electrodes are insulated from each other by an insulating base material). Next, a copper plate was placed on the other surface side of each anisotropic conductive film and subjected to main pressure bonding at 170 ° C. for 20 seconds to prepare each sample A. Next, the conduction performance of each sample A was measured with a tester (manufactured by AND, “AD5522”).

  Those having a resistance in the film thickness direction of 5Ω or less were evaluated as pass “◯”, and those exceeding 5Ω were evaluated as reject “x”.

(2) Evaluation of insulation performance in the film surface direction Evaluation of the insulation performance in the film surface direction was performed as follows. That is, one surface of each anisotropic conductive film was temporarily pressure-bonded to a comb-shaped electrode having a pitch of 30 μm. Next, a glass plate was placed on the other surface side of each anisotropic conductive film and subjected to main pressure bonding at 170 ° C. for 20 seconds to prepare each sample B. Next, the insulation performance of each sample B was measured with a tester.

Resistance of the film surface direction was evaluated as acceptable "○" of not less than 10 ⁷ Omega, was evaluated of less than 10 ⁷ Omega as unacceptable "×". In addition, among the samples that passed “◯”, those in which the resistance in the film surface direction was within the range of 10 ⁷ to 10 ⁸ Ω were rated “Δ”.

(Appearance of anisotropic conductive film)
Each anisotropic conductive film was stored for 24 hours at a temperature of 23 ° C. ± 2 ° C. after production, and then visually observed for appearance. At this time, the case where there was no blistering / peeling between the porous film and the adhesive layer was evaluated as a pass “◯”, and the case where blistering / peeling was observed was evaluated as a fail “x”.

  The above evaluation results are shown in Tables 1-2.

  According to Tables 1 and 2, the anisotropic conductive film according to Comparative Example 1 using the porous film according to Comparative Example 1 formed from siloxane-modified polyamideimide instead of the polyamideimide specified in the present invention is siloxane. It can be seen that due to the modification, the adhesion between the porous membrane and the adhesive layer is poor.

  In addition, as described above, the porous film according to Comparative Example 2 was compared with the porous film according to the Example. The manufacturing process was included, and the number of manufacturing steps was very large and complicated. Therefore, it turns out that the porous membrane which concerns on the comparative example 2, and the anisotropic electrically conductive film which uses this for the comparative example 2 are inferior in productivity.

  On the other hand, since the porous membrane according to the example uses a specific polyamideimide soluble in a hydrophobic solvent, the self-organization phenomenon is utilized in the same manner as other polymers soluble in a hydrophobic solvent. A honeycomb structure can be obtained without any problem even if the above-described film manufacturing method is used. Also, the number of manufacturing steps is simpler and less than that of Comparative Example 2. Therefore, it turns out that the porous membrane which concerns on an Example is excellent in productivity.

  Moreover, although the porous film which concerns on an Example is formed from the specific polyamide imide, it turns out that it has sufficient heat resistance.

  Moreover, it turns out that the anisotropic conductive film which concerns on the Example which used the porous film which concerns on an Example for a base film can express anisotropic conductivity without a problem. Furthermore, compared with the case where the porous film according to Comparative Example 1 formed from siloxane-modified polyamideimide is used as the base film, the adhesion between the porous film and the adhesive layer is excellent, and blistering and peeling are less likely to occur. It turns out that it is excellent in reliability.

  Although the embodiments and examples have been described above, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiments and examples, the case where the hole of the porous film is a through-hole is illustrated in detail, but the hole may be a non-through-hole, and variously selected according to the application. Can do.

  In order to form non-through holes, the coating thickness (cast amount) of the polymer solution described above is increased (increased), the concentration of polyamideimide contained in the polymer solution is increased, and the relative humidity is decreased. The film formation conditions may be adjusted as appropriate. Of these, it is most effective to increase the coating thickness of the polymer solution.

  Moreover, although the case where it uses for the base film material of an anisotropic conductive film was illustrated as a use of a porous film, this porous film is used for a large area, a flexible display device, an EL panel etc. other than that, for example. Fields of electronics such as surface light emitters, display devices, memory elements, nonlinear optical materials such as photonic crystals and optical waveguides, optics and electronics such as blocking of light energy conversion, chemical fields such as supports for various catalysts, microreactors, etc. It can be used in a wide range of fields such as biotechnology fields such as DNA chips and cell culture substrates.

It is the figure which showed typically the structure of the porous film which concerns on this embodiment, (a) is sectional drawing of a porous film, (b) is a top view of a porous film. It is the figure which showed typically the structure of the anisotropic electrically conductive film which concerns on this embodiment. 4 is an electron micrograph of a porous film according to Example 3. 7 is an electron micrograph of a porous film according to Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Porous film 12 Hole part 14 Inner wall surface 16 Partition 16a Constriction part 20 Anisotropic conductive film (ACF)
22 Conductive substance 24 Adhesive layer

Claims (6)

  A porous membrane comprising an acid component and a polyamideimide containing a diisocyanate component having a hydrophobic site or a diamine component having a hydrophobic site as polymerization components.   Polymer comprising at least an acid component, a polyamideimide containing a diisocyanate component having a hydrophobic site or a diamine component having a hydrophobic site as a polymerization component, an amphiphilic substance, and an organic solvent having hydrophobicity and volatility A porous film characterized in that it can be formed by allowing a support substrate cast with a solution to exist in an atmosphere having a relative humidity of 50% or more.   The porous membrane according to claim 1 or 2, wherein the hydrophobic portion is a cyclic hydrocarbon group.   The porous film according to any one of claims 1 to 3, wherein polyester is copolymerized with the polyamideimide.   5. The porous film according to claim 1, wherein the porous film has a large number of holes arranged in a honeycomb shape, and an inner wall surface of the hole is curved outward.   A porous membrane according to any one of claims 1 to 5, a conductive material filled in pores of the porous membrane, and an adhesive layer coated on both sides of the porous membrane. An anisotropic conductive film.