JP7361447B2 - Conductive resin composition, conductive adhesive sheet and laminate - Google Patents

Description

The present invention relates to a conductive resin composition and a conductive adhesive sheet that can be used, for example, to form a reinforcing section provided to prevent components mounted on a flexible printed wiring board from falling off.

2. Description of the Related Art As portable electronic terminals and the like become smaller and thinner, thin and bendable flexible printed wiring boards are widely used as wiring boards mounted thereon.

The flexible printed wiring board is generally known to have a configuration in which a ground circuit made of copper or the like is formed on the surface of a polyimide film or the like, and a component such as a connector is mounted on a part of the circuit.

As the flexible printed wiring board, one in which the ground circuit and other members are electrically connected using conductive adhesive tape is known in order to prevent the generation of noise due to the influence of electromagnetic waves. (For example, see Patent Document 1.).

However, when the amount of conductive filler used is increased in order to improve the electrical conductivity of the adhesive tape, the adhesiveness of the adhesive tape may be significantly reduced.

In addition, as electronic devices are required to be made thinner, reducing the thickness of the conductive adhesive tape containing a large amount of conductive filler will improve the adhesion of the conductive adhesive tape to the stepped portion of the flexible printed wiring board. The properties of these parts are significantly reduced, and air bubbles tend to remain at the interface between them, which may result in parts falling off or a decline in electromagnetic shielding properties.

International publication 2014/132951 pamphlet

The problem to be solved by the present invention is to provide a conductive adhesive tape that has both excellent conductivity and excellent adhesiveness, and a conductive resin composition that can be used for manufacturing the same.

The present inventor has developed a compound (A) having two or more epoxy groups, a conductive filler (B) containing a needle-like or scale-like conductive filler (b1), and a substantially spherical conductive filler (b2). The above problem has been solved by a conductive resin composition characterized by containing.

Since the conductive resin composition and the conductive adhesive sheet of the present invention have excellent conductivity and adhesive properties, they can be suitably used, for example, for fixing components constituting electronic devices. Further, the conductive resin composition and conductive adhesive sheet of the present invention can be suitably used for imparting electromagnetic shielding properties to a flexible printed wiring board, reinforcing it (forming a reinforcing layer), and the like.

The conductive resin composition of the present invention contains a compound (A) having two or more epoxy groups, a needle-like or scale-like conductive filler (b1), and a substantially spherical conductive filler (b2). A conductive resin composition containing a filler (B), the volume ratio of the needle-like or scale-like conductive filler (b1) to the approximately spherical conductive filler (b2) [(b1)/ (b2)] is 1/1 to 3/1.

As the compound (A), an epoxy resin having two or more epoxy groups exhibits excellent adhesive properties, and an epoxy resin having an average of 2 to 3 epoxy groups per molecule is suitable for use with metals such as copper, PET, polyimide, etc. In addition to excellent adhesion to plastic films, it has excellent dimensional stability before and after curing, and can also form a reinforcing layer with a level of rigidity that can further strengthen adherends such as flexible printed wiring boards. This is preferable because it is possible to impart rigidity to the cured product.

Specifically, the epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, dicyclopentadiene type epoxy resins such as dicyclopentadiene-phenol addition reaction type epoxy resin, and biphenyl type epoxy resins. Epoxy resin, tetramethylbiphenyl type epoxy resin, polyhydroxynaphthalene type epoxy resin, isocyanate modified epoxy resin, 10-(2,5-dihydroxyphenyl)-9,10-dihydro9-oxa-10-phosphaphenanthrene-10- Oxide modified epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, phenol aralkyl type epoxy resin, naphthol novolac type epoxy resin, naphthol aralkyl type epoxy resin, naphthol - Phenol-cocondensed novolac type epoxy resin, naphthol-cresol co-condensed novolac type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy resin, biphenyl-modified novolac type epoxy resin, etc. can be used.

Among them, the epoxy resin has a liquid epoxy equivalent weight of 100 to 350 g/eq. at 23°C. The epoxy resin (a1) has a solid epoxy equivalent weight of 200 to 2,000 g/eq. at 23°C. It is preferable to use the epoxy resin (a2), and it is more preferable to use them in combination in order to achieve both excellent rigidity and adhesiveness.

Examples of the epoxy resin (a1) include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, 1,6-dihydroxynaphthalene type epoxy resin, t-butylcatechol type epoxy resin, and 4,4' -diphenyldiaminomethane type epoxy resin, p- or m-aminophenol type epoxy resin, and the like.

The epoxy resin (a2) may be, for example, an epoxy resin obtained by reacting a bisphenol epoxy resin with a bisphenol compound, a dicyclopentadiene epoxy resin such as a dicyclopentadiene-phenol addition reaction epoxy resin, or a polyhydroxynaphthalene epoxy resin. Resin, isocyanate modified bisphenol type epoxy resin, 10-(2,5-dihydroxyphenyl)-9,10-dihydro 9-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resin, 2-methoxynaphthalene and orthocresol novolak Examples include copolymers of type epoxy resins, biphenylene type phenol aralkyl resins, phenol aralkyl resins, etc. Among them, dicyclopentadiene type epoxy resins such as dicyclopentadiene-phenol addition reaction type epoxy resins, isocyanate-modified bisphenol type epoxy resins, 10 -(2,5-dihydroxyphenyl)-9,10-dihydro 9-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resin is preferably used in order to achieve both rigidity and adhesiveness.

In addition, the epoxy resin preferably has an epoxy equivalent of 2000 g/eq. in addition to the epoxy resin (a1) and epoxy resin (a2). Above, preferably 2000g/eq. exceeding 10,000g/eq. The following epoxy resins can be used in combination.

Further, as the conductive filler (B) used in the conductive resin composition of the present invention, a combination of an acicular or scale-like conductive filler (b1) and a substantially spherical conductive filler (b2) is used.

The needle-like or scale-like conductive filler (b1) and the approximately spherical conductive filler (b2) have a volume ratio [(b1)/(b2)] of 1/1 to 4/1. It is preferable to use it within a range of 1.5/1 to 3/1 in order to obtain a conductive resin composition that has both excellent conductivity and adhesiveness. The conductive adhesive sheet obtained by using the conductive resin composition is obtained by adding an adhesive component such as the compound (A) having two or more epoxy groups when the conductive adhesive sheet is thermally cured. Since flow can be suppressed, it has excellent handling and processing suitability.

Examples of the acicular or scaly conductive filler (b1) include metal particles such as gold, silver, copper, nickel, stainless steel, and aluminum, carbon, and graphite, as well as acicular or scaly resins and Glass flakes or the like whose surfaces are coated with metal can be used, and among them, it is preferable to use nickel or copper, and it is especially preferable to use acicular nickel manufactured by the carbonyl method. This is more preferable in terms of exhibiting high conductivity. Specifically, as the conductive filler, nickel powder NI255, NI287 (manufactured by Inco Limited), etc. manufactured by the carbonyl method can be suitably used.

The conductive filler (b1) preferably has an acicular or scaly shape with an average aspect ratio of more than 3.

As the conductive filler (b1), it is preferable to use one whose 50% average volume particle diameter is 0.1 to 200 μm, more preferably 1 to 100 μm, and more preferably 15 to 50 μm. It is more preferable to use a filler with a diameter of 15 to 40 μm, since this achieves both good dispersibility of the conductive filler in the conductive resin composition and ease of coating. It is particularly preferable. The 50% volume particle diameter of the conductive filler is a value measured using a laser diffraction particle size distribution analyzer SALD-3000 manufactured by Shimadzu Corporation and using isopropanol as a dispersion medium.

In addition, the "long axis average length L", "short axis average length d", and "average thickness T" of the conductive filler used in calculating the aspect ratio (L/t) are determined using a scanning electron microscope (SEM). ) was measured by observing a SEM photograph taken using a camera. "Major axis average length L" and "minor axis average length d" are measured with the longest straight line as the major axis and its length as the "major axis length" L. The main trunk is the part that can be approximated by a rectangle. The longest length d in the direction perpendicular to the long axis of the particle was measured as the "short axis length", and the aspect ratio was calculated from the ratio thereof. When there is a part (branch) that protrudes from the main trunk in a direction different from the direction of the main trunk, the longest major axis part is defined as L, and the part corresponding to the width of the major axis is defined as short axis d.

Further, the approximately spherical conductive filler (b2) can effectively suppress a decrease in the conductivity due to the formation of an oxide film on the surface of the conductive filler due to the influence of heat, and In order to reduce the production cost of the curable material, it is preferable to use stainless steel particles, nickel particles, or the like.

The conductive filler (b2) may have a true spherical or elliptical shape, and preferably has an aspect ratio of less than 2 on average.

As the conductive filler (b2), it is preferable to use one whose 50% average volume particle diameter is 0.1 to 200 μm, more preferably 1 to 100 μm, and more preferably 15 to 50 μm. It is more preferable to use a filler with a diameter of 15 to 40 μm, since this achieves both good dispersibility of the conductive filler in the conductive resin composition and ease of coating. It is particularly preferable. The 50% volume particle diameter of the conductive filler is a value measured using a laser diffraction particle size distribution analyzer SALD-3000 manufactured by Shimadzu Corporation and using isopropanol as a dispersion medium.

In addition, the conductive filler (B) is 5.0 g/cm ³ because it is difficult to sediment in the conductive resin composition and can maintain a relatively uniform dispersion state for several hours. It is preferable to use one having the following apparent density, more preferably to use one having an apparent density of 4.5 g/cm ³ or less, particularly preferably 4.0 g/cm ³ or less. The apparent density of the conductive filler (B) is a value measured in accordance with JIS Z2504-2000 "Method for measuring apparent density of metal powder".

In addition, the conductive filler (B) may be a titanate coupling agent or A conductive filler surface-treated with an aluminate coupling agent or the like may also be used.

The conductive filler (B) is preferably used in a volume ratio of 10% to 50% by volume, and 10% to 30% by volume relative to the total volume of the compound (A) and the conductive filler (B). It is more preferable to use it in a range of 20 to 30 volume %, and even more preferably in a range of 20 to 30 volume %. When the amount of conductive filler used increases, while usually exhibiting excellent conductivity, it may cause a significant decrease in adhesion. However, with the conductive resin composition of the present invention, excellent adhesiveness can be maintained even when the amount of conductive filler (B) used is increased. The conductive adhesive sheet obtained by this method can suppress the flow of adhesive components such as the compound (A) having two or more epoxy groups when the conductive adhesive sheet is thermally cured. Excellent processing suitability.

As the conductive resin composition of the present invention, one containing other components as necessary in addition to the compound (A) and the conductive filler (B) can be used.

In addition, the other components include electrical fillers other than the conductive filler (B) such as aluminum hydroxide, aluminum oxide, aluminum nitride, magnesium hydroxide, magnesium oxide, mica, talc, boron nitride, and glass flakes. An insulating filler or the like can be used.

Further, as the other components, if a thermosetting resin such as the epoxy resin is used as the compound (A), it is preferable to use a curing agent that can react with the thermosetting resin.

As the curing agent, for example, when an epoxy resin or acrylic resin having an epoxy group is used as the compound (A), it is preferable to use one having a functional group capable of reacting with the epoxy group.

Examples of the curing agent include amine compounds, amide compounds, acid anhydride compounds, and phenol compounds. For example, as the amine compound, diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, imidazole derivatives, BF3-amine complexes, guanidine derivatives, etc. can be used.

Examples of the amide compounds include dicyandiamide, polyamide resins synthesized from linolenic acid dimer and ethylenediamine, and examples of the acid anhydride compounds include phthalic anhydride, trimellitic anhydride, and Pyromellitic acid, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc., and examples of the phenolic compound include phenol novolac Resin, cresol novolak resin, aromatic hydrocarbon formaldehyde resin modified phenolic resin, dicyclopentadiene phenol addition type resin, phenol aralkyl resin (Zyrock resin), naphthol aralkyl resin, trimethylolmethane resin, tetraphenyloleethane resin, naphthol novolak resin , naphthol-phenol co-condensed novolac resin, naphthol-cresol co-condensed novolac resin, biphenyl-modified phenol resin (a polyhydric phenol compound in which phenol nuclei are linked by bismethylene groups), biphenyl-modified naphthol resin (phenol nuclei are linked by bismethylene groups), polyhydric naphthol compounds), aminotriazine-modified phenolic resins (compounds with a phenol skeleton, triazine ring, and primary amino group in their molecular structure) and alkoxy group-containing aromatic ring-modified novolac resins (formaldehyde can remove phenol cores and alkoxy group-containing aromatic resins). Examples include polyhydric phenol compounds such as polyhydric phenol compounds in which rings are connected.

The curing agent is preferably used in a range of 1 part by mass to 60 parts by mass, and preferably in a range of 5 parts by mass to 30 parts by mass, based on a total of 100 parts by mass of the compound (A) such as the epoxy resin. It is preferable to do so.

Moreover, a curing accelerator can be used as the other component. As the curing accelerator, phosphorus compounds, amine compounds, imidazole derivatives, etc. can be used. When using the curing accelerator, the amount used is preferably 0.1 parts by mass to 5 parts by mass, and 0.5 parts by mass, based on a total of 100 parts by mass of the compound (A) such as the epoxy resin. More preferably, the amount is in the range of 3 parts by mass.

As the curing agent and curing accelerator, it is preferable to use one that is in powder form and does not dissolve in the resin composition at room temperature. The powdered curing accelerator suppresses the thermosetting reaction at low temperatures compared to the liquid curing accelerator, so it further improves the storage stability of the thermosetting material at room temperature before thermosetting. can be improved.

In addition, the conductive resin composition has a heat-cured material that is heat-cured to ensure toughness that does not cause defects, etc., even when the thermo-cured material is used in an environment with large temperature changes. Those containing plastic resin can be used.

As the thermoplastic resin, for example, thermoplastic polyester resin, thermoplastic urethane resin, etc. can be used. Among them, it is preferable to use thermoplastic polyester resin, and polyether ester amide resin, polyvinyl acetoacetal resin, etc. When the conductive resin composition and conductive adhesive sheet of the present invention are thermally cured, the use thereof can suppress the flow of the conductive resin composition and the conductive adhesive sheet, and also have good brittleness at the level described above. and a level of rigidity that can sufficiently reinforce adherends such as flexible printed wiring boards.

For the above reasons, the thermoplastic resin is preferably used in an amount of 1 to 100 parts by weight, more preferably 5 parts to 40 parts by weight, based on 100 parts by weight of the compound (A). preferable.

As described above, the conductive resin composition can be used as a conductive adhesive sheet previously formed into any shape such as a sheet. The conductive resin composition may contain a solvent in addition to the compound (A), the conductive filler (B), a curing agent, etc. in order to improve the work efficiency when manufacturing a conductive adhesive sheet using the conductive resin composition. It is preferable to use one that does.

Examples of the solvent include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ketyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; aromatic solvents such as toluene and xylene. Hydrocarbons etc. can be used.

In addition to the above-mentioned materials, the conductive resin composition may also include fillers, softeners, stabilizers, adhesion promoters, leveling agents, antifoaming agents, and plasticizers within the range that does not impair the effects of the present invention. , tackifying resins, fibers, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, thickeners, colorants such as pigments, fillers, and other additives can be used.

The conductive resin composition of the present invention can be produced by mixing the compound (A), the conductive filler (B), and arbitrary components such as a curing agent and a solvent.

When mixing the above-described components to produce a conductive resin composition, a dissolver, butterfly mixer, BDM twin-shaft mixer, planetary mixer, etc. can be used as necessary, and a dissolver or butterfly mixer can be used. is preferable, and when the conductive filler is used, it is preferable to use a planetary mixer in order to improve its dispersibility.

The curing agent and curing accelerator are preferably used before thermally curing the conductive resin composition or before forming the conductive resin composition into a sheet or the like to produce a conductive adhesive sheet.

Further, the conductive adhesive sheet can be prepared by mixing the compound (A), the conductive filler (B), and the optional components to produce a conductive resin composition, and then applying it to the surface of, for example, a release liner. It can be manufactured by coating and drying.

The drying is preferably performed at a temperature of about 50° C. to 120° C., more preferably about 50° C. to 90° C., in order to prevent the thermosetting reaction of the thermosetting material from proceeding.

The conductive adhesive sheet may be held between the release liners before being attached to an adherend such as a flexible printed wiring board.

Examples of the release liner include paper such as kraft paper, glassine paper, and high-quality paper; resin films such as polyethylene, polypropylene (OPP, CPP), and polyethylene terephthalate; laminated paper obtained by laminating the above paper and a resin film; It is possible to use a material that has been sealed with clay, polyvinyl alcohol, or the like, and then has one or both sides subjected to a release treatment using silicone resin or the like.

The conductive adhesive sheet preferably has a thickness in the range of 50 to 350 μm before thermosetting, more preferably 100 to 350 μm, and 115 to 300 μm. This is preferable because it is less likely to cause cracks or the like when it is wound into a roll.

The conductive adhesive sheet preferably has a thickness in the range of 50 to 350 μm after thermosetting, more preferably 80 to 300 μm, and 100 to 350 μm. It has excellent dimensional stability before and after heat curing, is easy to handle, and has reached a level where it is possible to prevent mounted components from falling off without using metal reinforcing plates, which are a factor in thicker films in electronic devices. It is more preferable because it can exhibit a level of rigidity that can strongly reinforce the flexible printed wiring board.

The conductive adhesive sheet may be a sheet-like material that has almost no tackiness at room temperature, melts when heated to a temperature of about 100°C or higher, and bonds two or more adherends ( (joining) is preferable.

The conductive adhesive sheet has a tensile modulus (x1) of 5 to 2,500 MPa at 25°C before thermosetting, which makes it easy to form into any shape with high precision by punching, making it suitable for flexible printing. It is easy to process into any shape according to the shape of the part of the wiring board that requires reinforcement, and has excellent conformability to stepped parts of adherends such as flexible printed wiring boards. It is preferable in terms of exhibiting adhesiveness and conductivity.

As the conductive adhesive sheet, it is preferable to use a sheet whose tensile elastic modulus (x1) at 25° C. is in the range of 5 to 1,000 MPa, because it is easy to punch out as described above, and it can be rolled into a roll. This is preferable because it is less likely to cause cracks when removed.

Further, as the conductive adhesive sheet, it is preferable to use one whose tensile elastic modulus (x2) at 25°C after thermosetting is in the range of 4,000 MPa or more. This is more preferable in terms of reinforcement to a practically sufficient level. Further, the upper limit of the tensile modulus (x2) is not particularly limited, but is preferably 10,000 MPa or less, more preferably 7,000 MPa or less.

Here, the tensile modulus (x2) refers to the tensile modulus at 25° C. of a thermoset material obtained by heating the thermosetting material at 165 ° C. for 120 minutes.

Further, as the conductive resin composition and conductive adhesive sheet of the present invention, it is preferable to use those having a volume resistivity of 0.1 to 50 mΩ·cm, and preferably 0.1 to 20 mΩ·cm.・When mounting a flexible printed wiring board with reinforcing parts (described later) on an electronic device, it is recommended to use a material with a conductive sponge or other material in the ground wiring that forms the flexible printed wiring board with reinforcing parts. This is more preferable because the metal panels can be electrically connected through the material, and as a result, noise emitted from electronic equipment can be effectively suppressed. The volume resistivity of the thermoset of the conductive resin composition and the conductive adhesive sheet may be the same as or different from that before thermosetting, but the volume resistivity of the thermoset may also be the same as the above-mentioned preferred volume resistivity. When mounting a flexible printed wiring board with reinforcing parts on an electronic device, it is necessary to ensure that the metal panel is within this range through a cushioning material such as conductive sponge on the ground wiring that makes up the flexible printed wiring board with reinforcing parts. It is more preferable because it can be electrically connected and, as a result, noise emitted from the electronic device can be effectively suppressed.

Note that the volume resistance value refers to a value measured using a resistivity meter Loresta-GP MCP-T600 (manufactured by Mitsubishi Chemical Corporation).

The conductive resin composition and conductive adhesive sheet of the present invention obtained by the above method are relatively flexible before curing, so they have excellent step conformability to adherends, and after thermosetting, they are very flexible. Since it becomes extremely hard and can sufficiently reinforce the adherend, it can be used exclusively as a material for forming the reinforcing portion of flexible printed wiring boards.

The flexible printed wiring board is often used as a flexible printed wiring board with a reinforcing part, which has a structure in which a flexible printed wiring board and a reinforcing part are laminated. Conventionally, a stainless steel plate has been used as the reinforcing part, but in the present invention, the thermoset of the conductive resin composition and the conductive adhesive sheet can be used alone as the reinforcing part. . Therefore, it is possible to achieve both thinning of the flexible printed wiring board and excellent step followability with respect to a stepped portion caused by, for example, an opening in the flexible printed wiring board.

The tensile modulus (x3) of the reinforcing portion at 25° C. is preferably 2,500 MPa or more, more preferably 3,000 MPa or more, and 4,000 to 20,000 MPa. It is further preferred because the flexible printed wiring board can be strongly reinforced without using a stainless steel plate or the like.

The reinforcing portion can be obtained, for example, by heating and curing the conductive resin composition and the conductive adhesive sheet at a temperature of preferably 120° C. or higher, more preferably 120 to 200° C., for 5 to 120 minutes. can.

The flexible printed wiring board having the reinforcing portion is generally referred to as a flexible printed wiring board with reinforcing portion, and is mounted on an electronic device.

The flexible printed wiring board with a reinforcing portion can be produced by the step [1] of attaching or applying the conductive resin composition and the conductive adhesive sheet to the back surface of the flexible printed wiring board relative to the mounting surface, and the conductive resin composition. It can be manufactured by going through step [2] of forming a reinforcing portion by heating the material and the conductive adhesive sheet to 120° C. or higher and thermally curing it.

The mounting of the components on the flexible printed wiring board may be performed in advance before the step [1], but the mounting step is performed after the step [1] and the step [2]. This is preferable in order to effectively prevent connection failures of the components.

The flexible printed wiring board with reinforcing portions is mainly installed in portable electronic devices such as smartphones and electronic devices such as personal computers. At that time, a cushioning material is laminated on the surface of the reinforcing part of the flexible printed wiring board and the flexible printed wiring board with the reinforcing part, directly or through another layer, and the flexible printed wiring board is mounted on the electronic device. It is preferable.

The lamination with the cushioning material may be in a state in which they are adhered with an adhesive component or the like, or in a state in which they are simply in contact with each other.

Examples of the cushioning material include urethane foam, polyethylene foam, silicone sponge, etc., and it is preferable to use conductive urethane foam.

The cushioning material preferably has a thickness of about 0.1 to 5.0 mm.

An electronic device having a structure in which the cushioning material is laminated effectively suppresses malfunctions caused by noise.

Examples and comparative examples will be specifically explained below.

(Example 1)
200 parts by mass of a methyl ethyl ketone solution (solid content 30% by mass) of JER-1256 (manufactured by Mitsubishi Chemical Corporation, bisphenol A epoxy resin, epoxy equivalent 8,000 g/eq.), 850-S (manufactured by DIC Corporation, bisphenol A 10 parts by mass of type epoxy resin, epoxy equivalent: 188 g/eq.), methyl ethyl ketone solution (solid content: 70 mass%) of HP-7200 (manufactured by DIC Corporation, dicyclopentadiene type epoxy resin, epoxy equivalent: 285 g/eq.) 42 A thermosetting resin composition (X-1) was prepared by mixing 0.9 parts by mass and 2.0 parts by mass of DICY-7 (dicyandiamide, manufactured by Mitsubishi Chemical Corporation).

Next, as an acicular conductive filler, NI-255 (nickel powder manufactured by Inco Limited, average aspect ratio exceeding 3, 50% average particle diameter: 21 μm, apparent density: 0.6 g/cm ³ , acicular) 217.3 parts by mass based on 100 parts by mass of the solid content of the thermosetting resin composition (X-1), and DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder) as a substantially spherical conductive filler. , average aspect ratio less than 2, 50% average particle diameter: 10.7 μm, tap density: 4.1 g/cm ³ , round shape), and stir for 10 minutes using a dispersion stirrer. A conductive thermosetting resin composition (Y-1) was obtained.

Next, the conductive thermosetting resin composition (Y-1) was applied to the surface of a release liner (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was treated with a silicone compound for release) using a rod-shaped metal applicator. The coating was applied to a dry thickness of 140 μm using a drying machine.

Next, the coated material was placed in a dryer at 85° C. for 5 minutes and dried to obtain a conductive adhesive sheet (Z-1) with a thickness of 140 μm.

(Example 2)
2MA-OK (manufactured by Shikoku Kasei Kogyo Co., Ltd., 2,4-diamino-6-[2'-methylimidazolyl-(1')) instead of 2.0 parts by mass of DICY-7 (manufactured by Mitsubishi Chemical Corporation, dicyandiamide) ]-Ethyl-s-triazine isocyanuric acid adduct)) The conductive thermosetting resin composition (Y-2) and the conductive thermosetting resin composition (Y-2) with a thickness of 140 μm were prepared in the same manner as in Example 1 except for using 2 parts by mass of An adhesive sheet (Z-2) was obtained.

(Example 3)
The amount of methyl ethyl ketone solution (solid content 30% by mass) of JER-1256 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin) was changed from 200 parts by mass to 133.3 parts by mass, and 850-S (DIC Corporation) 10 parts by mass of 830-S (bisphenol F type epoxy resin, epoxy equivalent weight 170 g/eq.) was used instead of EXA-9726 (manufactured by DIC Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent weight 188 g/eq.). Conductive thermosetting was performed in the same manner as in Example 1, except that 28.6 parts by mass of a methyl ethyl ketone solution (solid content 70% by mass) of a phosphorus-modified epoxy resin (epoxy equivalent: 475 g/eq.) manufactured by the company was used. A conductive resin composition (Y-3) and a conductive adhesive sheet (Z-3) having a thickness of 140 μm were obtained.

(Example 4)
The amount of methyl ethyl ketone solution (solid content 30% by mass) of JER-1256 (manufactured by Mitsubishi Chemical Corporation, bisphenol A epoxy resin) was changed from 133.3 parts by mass to 166.7 parts by mass, and EXA-9726 (DIC TSR-400 (manufactured by DIC Corporation, isocyanate-modified bisphenol A type epoxy resin, epoxy equivalent 343 g/eq.) instead of the methyl ethyl ketone solution (solid content 70% by mass) of phosphorus-modified epoxy resin, epoxy equivalent 475 g/eq. Using 50 parts by mass of a methyl ethyl ketone solution (solid content 80 mass %) of % by mass) was changed from 42.9 parts by mass to 0 parts by mass, and 2MA-OK (Shikoku Kasei Kogyo Co., Ltd.) was used instead of 2.0 parts by mass of DICY-7 (manufactured by Mitsubishi Chemical Corporation, dicyandiamide). The same method as in Example 3 except that 1 part by mass of 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (manufactured by the company) was used. A conductive thermosetting resin composition (Y-4) and a conductive adhesive sheet (Z-4) having a thickness of 140 μm were obtained.

(Example 5)
The amount of 2MA-OK (manufactured by Shikoku Kasei Kogyo Co., Ltd., 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct) is from 1 part by mass. 0.9 parts by mass, and further using 1.5 parts by mass of DICY-7 (manufactured by Mitsubishi Chemical Corporation, dicyandiamide) and 5.4 parts by mass of 4,4'-diaminodiphenylsulfone. A conductive thermosetting resin composition (Y-5) and a conductive adhesive sheet (Z-5) having a thickness of 140 μm were obtained in the same manner as in Example 4.

(Example 6)
The amount of the NI-255 (nickel powder manufactured by Inco Limited, 50% average particle size: 21 μm, apparent density: 0.6 g/cm ³ , acicular) was changed from 217.3 parts by mass to 162 parts by mass. , and the amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was 96.8 mass. A conductive thermosetting resin composition (Y-6) and a conductive adhesive sheet (Z-6) with a thickness of 140 μm were obtained in the same manner as in Example 4, except that the amount was changed from 145 parts by mass to 145 parts by mass. Ta.

(Example 7)
The amount of 830-S (manufactured by DIC Corporation, bisphenol F type epoxy resin, epoxy equivalent 170 g/eq.) was changed from 10 parts by mass to 20 parts by mass, and TSR-40 (manufactured by DIC Corporation, isocyanate-modified bisphenol A type epoxy resin, epoxy equivalent: 343 g/eq.), 30 parts by mass of 1055 (manufactured by DIC Corporation, bisphenol A type epoxy resin, epoxy equivalent: 475 g/eq.) was used, JER-1256 (manufactured by Mitsubishi Chemical Corporation) , bisphenol A type epoxy resin) was changed from 166.7 parts by mass to 150 parts by mass, 5 parts by mass of S-LEC KS-1 (manufactured by Sekisui Chemical Co., Ltd., polyvinyl acetal resin) was used, and DN Conductive thermosetting resin composition (Y-7) and thickness A 140 μm conductive adhesive sheet (Z-7) was obtained.

(Example 8)
The amount of NI-255 (nickel powder manufactured by Inco Limited, 50% average particle size: 21 μm, apparent density: 0.6 g/cm ³ , needle-like) was changed from 217.3 parts by mass to 168 parts by mass, And, the amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was 96.8 parts by mass. A conductive thermosetting resin composition (Y-8) and a conductive adhesive sheet (Z-8) having a thickness of 140 μm were prepared in the same manner as in Example 7 except that the amount was changed from 75.2 parts by mass to 75.2 parts by mass. Obtained.

(Example 9)
The amount of NI-255 (nickel powder manufactured by Inco Limited, 50% average particle size: 21 μm, apparent density: 0.6 g/cm ³ , needle shape) was changed from 217.3 parts by mass to 271.3 parts by mass. And, the amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was 96.8 A conductive thermosetting resin composition (Y-9) and a conductive adhesive sheet (Z-9 with a thickness of 140 μm) were prepared in the same manner as in Example 7 except that parts by mass were changed to 121.5 parts by mass. ) was obtained.

(Example 10)
The amount of NI-255 (nickel powder manufactured by Inco Limited, 50% average particle size: 21 μm, apparent density: 0.6 g/cm ³ , needle-like) was changed from 217.3 parts by mass to 162 parts by mass, And, the amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was 96.8 parts by mass. A conductive thermosetting resin composition (Y-10) and a conductive adhesive sheet (Z-10) with a thickness of 140 μm were prepared in the same manner as in Example 7 except that the amount was changed from 145.1 parts by mass to 145.1 parts by mass. Obtained.

(Example 11)
The amount of NI-255 (nickel powder manufactured by Inco Limited, 50% average particle diameter: 21 μm, apparent density: 0.6 g/cm ³ , acicular) was changed from 217.3 parts by mass to 243 parts by mass, And, the amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was 96.8 parts by mass. A conductive thermosetting resin composition (Y-11) and a conductive adhesive sheet (Z-11) with a thickness of 140 μm were prepared in the same manner as in Example 7, except that the amount was changed from 72.5 parts by mass to 72.5 parts by mass. Obtained.

(Example 12)
NI-123 (manufactured by Inco Limited Co., Ltd.) instead of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) Conductive thermosetting was performed in the same manner as in Example 11, except that 81 parts by mass of nickel powder, 50% average particle diameter: 11.7 μm, apparent density: 2.5 g/cm ³ , round shape) was used. A conductive resin composition (Y-12) and a conductive adhesive sheet (Z-12) having a thickness of 140 μm were obtained.

(Example 13)
NI-123 (manufactured by Inco Limited Co., Ltd.) instead of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) Conductive thermosetting was performed in the same manner as in Example 7, except that 108 parts by mass of nickel powder, 50% average particle diameter: 11.7 μm, apparent density: 2.5 g/cm ³ , round shape) was used. A conductive resin composition (Y-13) and a conductive adhesive sheet (Z-13) having a thickness of 140 μm were obtained.

(Example 14)
A conductive adhesive sheet (Z-14) was obtained in the same manner as in Example 7 except that the thickness of the conductive adhesive sheet was changed from 140 μm to 160 μm.

(Example 15)
A conductive adhesive sheet (Z-15) was obtained in the same manner as in Example 7 except that the thickness of the conductive adhesive sheet was changed from 140 μm to 110 μm.

(Example 16)
A conductive adhesive sheet (Z-16) was obtained in the same manner as in Example 7 except that the thickness of the conductive adhesive sheet was changed from 140 μm to 90 μm.

(Example 17)
The amount of NI-255 (nickel powder manufactured by Inco Limited, 50% average particle size: 21 μm, apparent density: 0.6 g/cm ³ , acicular) was changed from 217.3 parts by mass to 259 parts by mass, And, the amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was 96.8 parts by mass. A conductive thermosetting resin composition (Z-17) and a conductive adhesive sheet (Z-17) with a thickness of 140 μm were obtained in the same manner as in Example 7, except that the amount was changed from 58 parts by mass to 58 parts by mass. .

(Comparative example 1)
The amount of NI-255 (nickel powder manufactured by Inco Limited) was changed from 217.3 parts by mass to 324 parts by mass, and the amount of DAP-316L-HTD (stainless steel powder manufactured by Daido Steel Co., Ltd.) was changed from 217.3 parts by mass to 324 parts by mass. 96.8 parts by mass was changed to 0 parts by mass, and 830-S (manufactured by DIC Corporation, bisphenol A type epoxy resin, epoxy equivalent: 188 g/eq.) was replaced with 850-S (manufactured by DIC Corporation, bisphenol A type epoxy resin, epoxy equivalent: 188 g/eq.). A conductive thermosetting resin composition (Y'-1) and a film having a thickness of 140 μm were prepared in the same manner as in Example 1, except that 10 parts by mass of F-type epoxy resin (epoxy equivalent: 170 g/eq.) was used. A conductive adhesive sheet (Z'-1) was obtained.

(Comparative example 2)
The amount of NI-255 (nickel powder manufactured by Inco Limited) was changed from 217.3 parts by mass to 0 parts by mass, and the amount of DAP-316L-HTD (stainless steel powder manufactured by Daido Steel Co., Ltd.) was changed from 217.3 parts by mass to 0 parts by mass. 96.8 parts by mass to 290.3 parts by mass, and 830-S (manufactured by DIC Corporation, bisphenol A type epoxy resin, epoxy equivalent: 188 g/eq.) instead of 850-S (manufactured by DIC Corporation). A conductive thermosetting resin composition (Y'-2) and a thickness A 140 μm conductive adhesive sheet (Z'-2) was obtained.

(Comparative example 3)
The amount of NI-255 (nickel powder manufactured by Inco Limited) was changed from 162 parts by mass to 190 parts by mass, and the amount of DAP-316L-HTD (stainless steel powder manufactured by Daido Steel Co., Ltd.) was changed to 145 parts by mass. parts to 0 parts by mass, and the amount of methyl ethyl ketone solution (solid content 30% by mass) of JER-1256 (manufactured by Mitsubishi Chemical Corporation, bisphenol A epoxy resin) was changed from 166.7 parts by mass to 200 parts by mass. and changed the methyl ethyl ketone solution (solid content 80% by mass) of TSR-400 (manufactured by DIC Corporation, isocyanate-modified bisphenol A type epoxy resin, epoxy equivalent: 343 g/eq.) from 50 parts by mass to 37.5 parts by mass. Except for the above, a conductive thermosetting resin composition (Y'-3) and a conductive adhesive sheet (Z'-3) having a thickness of 140 μm were obtained in the same manner as in Example 6.

(Comparative example 4)
The amount of NI-255 (nickel powder manufactured by Inco Limited) was changed from 162 parts by mass to 108 parts by mass, and the amount of DAP-316L-HTD (stainless steel powder manufactured by Daido Steel Co., Ltd.) was changed to 145 parts by mass. A conductive thermosetting resin composition (Y'-4) and a 140 μm thick conductive adhesive sheet (Z'- 4) was obtained.

(Comparative example 5)
NI-123 (nickel powder manufactured by Inco Limited, 50%) instead of NI-255 (nickel powder manufactured by Inco Limited, 50% Average particle size: 21 μm, apparent density: 0.6 g/cm ³ , acicular) A conductive thermosetting resin composition was prepared in the same manner as in Example 7, except that 217.3 parts by mass of average particle diameter: 11.7 μm, apparent density: 2.5 g/cm ³ , round shape) was used. (Y'-5) and a conductive adhesive sheet (Z'-5) having a thickness of 140 μm were obtained.

(Comparative example 6)
The amount of NI-123 (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle diameter: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was varied from 217.3 parts by mass to 337 parts by mass. and changed the amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) to 96.8 A conductive thermosetting resin composition (Y'-6) and a 140 μm thick conductive adhesive sheet (Z'-6) were prepared in the same manner as in Comparative Example 5, except that parts by mass were changed to 149 parts by mass. ) was obtained.

(Comparative example 7)
The amount of NI-123 (nickel powder manufactured by Inco Limited, 50% average particle diameter: 11.7 μm, apparent density: 2.5 g/cm ³ , round shape) was changed from 217.3 parts by mass to 506 parts by mass. The amount of DAP-316L-HTD (manufactured by Daido Steel Co., Ltd., stainless steel powder, 50% average particle size: 10.7 μm, tap density: 4.1 g/cm ³ , round shape) was 96.8 parts by mass. A conductive thermosetting resin composition (Y'-7) and a conductive adhesive sheet (Z'-7) with a thickness of 140 μm were prepared in the same manner as in Comparative Example 5, except that the amount was changed from 223 parts by mass to 223 parts by mass. Obtained.

(Comparative example 8)
The amount of NI-255 (nickel powder manufactured by Inco Limited, 50% average particle size: 21 μm, apparent density: 0.6 g/cm ³ , needle-like) was changed from 217.3 parts by mass to 108.7 parts by mass. And, except that 108.7 parts by mass of NI-123 (nickel powder manufactured by Inco Limited, 50% average particle diameter: 11.7 μm, apparent density: 2.5 g/cm ³ , round shape) was used. In the same manner as in Example 7, a conductive thermosetting resin composition (Y'-8) and a conductive adhesive sheet (Z'-8) having a thickness of 140 μm were obtained.

[Method for measuring the thickness of conductive adhesive sheet after thermosetting]
Test piece 1 was obtained by cutting the conductive adhesive sheet from which the release liner had been removed into a size of 10 mm width x 100 mm length.

Next, the test piece 1 was sandwiched between two sheets of NITFLON (PTFE film, manufactured by Nitto Denko Corporation) with a thickness of 0.1 mm, and was heated to 60°C at 165°C while being pressurized at 2MPa using a heat press machine. Test piece 2 (after heat curing) was obtained by heating and curing for 30 minutes.

The thickness of the test piece 2 (after thermosetting) was measured using a thickness meter "TH-102" manufactured by Tester Sangyo Co., Ltd.

[Measurement method of tensile modulus (x1) and tensile modulus (x2) at 25°C]
The tensile modulus (x1) of the test piece 1 (before curing) at 25° C. was measured using a Tensilon tensile tester at a tensile speed of 20 mm/min.

The tensile modulus (x2) of the test piece 2 (after thermosetting) at 25° C. was measured using a Tensilon tensile tester at a tensile speed of 20 mm/min.

[Adhesive flow amount]
The conductive adhesive was prepared by punching three holes with a diameter of 6 mm between a 25 μm thick polyimide film (manufactured by DuPont-Toray Co., Ltd., product name: Kapton 100H) and a 35 μm thick copper foil (glossy surface). The sandwiched sheet was pressed at a temperature of 165° C. and a pressure of 2 MPa for 60 minutes.

After the pressing, the maximum exudation distance of the adhesive into the inside of the punched hole was measured for each punched hole using an optical microscope, and the average distance was defined as the "adhesive flow amount [mm]".

[Method of measuring volume resistivity]
Prepare the same test piece 2 (after thermosetting) as above, cut it into a size of 50 x 80 mm, and measure the volume resistivity of test piece 3 using a resistivity meter (manufactured by Mitsubishi Chemical Corporation). The measurement was performed using a four-probe method using a "Loresta-GP MCP-T600").

[Adhesive evaluation method]
Test piece 3 was prepared by cutting the conductive adhesive sheets obtained in Examples and Comparative Examples into a size of 20 mm width x 100 mm length.

The test piece 3 was sandwiched between an aluminum plate with a thickness of 1.5 mm and an electrolytic copper foil with a thickness of 35 μm, and they were thermally bonded at 180°C for 10 minutes while maintaining a pressure of 1 MPa using a heat press machine, and then heated at 180°C. By leaving the test piece 3 in an environment for 50 minutes to heat cure it, a copper foil laminated laminate in which an aluminum plate and an electrolytic copper foil were bonded using the test piece 3 was produced.

The copper foil laminated board was left to stand in an atmosphere of 23°C x 50% RH for 1 hour, and then the adhesive strength was measured when it was peeled in the 180° direction (peeling speed 50 mm/min) under the same environment.

Claims (6)

A conductive resin composition containing a compound (A) having two or more epoxy groups and a conductive filler (B) containing an acicular conductive filler (b1) and a substantially spherical conductive filler (b2). And,
The compound (A) has a liquid epoxy equivalent weight of 100 to 350 g/eq. at 23°C. An epoxy resin (a1) having a solid epoxy equivalent weight of 200 to 2,000 g/eq. at 23°C. It contains an epoxy resin (a2) which is
The volume ratio [(b1)/(b2)] of the acicular conductive filler (b1) and the approximately spherical conductive filler (b2) is 1/1 to 3/1,
A conductive resin composition characterized in that the volume ratio of the conductive filler (B) to the total volume of the compound (A) and the conductive filler (B) is in the range of 10% by volume to 40% by volume. The conductive resin composition according to claim 1, wherein the volume ratio of the conductive filler (B) to the total volume of the compound (A) and the conductive filler (B) is in the range of 10% by volume to 36% by volume. . A conductive adhesive sheet comprising the conductive resin composition according to claim 1 or 2 . The conductive adhesive sheet according to claim 3 , having a thickness in the range of 50 μm to 350 μm. The tensile modulus (x1) at 25 ° C. is in the range of 5 MPa to 2,500 MPa,
The conductive adhesive sheet according to claim 3 or 4 , wherein the thermoset material has a tensile modulus (x2) at 25° C. of 2,500 MPa or more. A laminate having a structure in which a thermoset of the conductive adhesive sheet according to any one of claims 3 to 5 is laminated on a flexible printed wiring board.