CN108026420B - Conductive adhesive and shielding film - Google Patents
Conductive adhesive and shielding film Download PDFInfo
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- CN108026420B CN108026420B CN201780003071.9A CN201780003071A CN108026420B CN 108026420 B CN108026420 B CN 108026420B CN 201780003071 A CN201780003071 A CN 201780003071A CN 108026420 B CN108026420 B CN 108026420B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
- C09J9/02—Electrically-conducting adhesives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/04—Non-macromolecular additives inorganic
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J163/00—Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J167/00—Adhesives based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Adhesives based on derivatives of such polymers
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
- C09J175/04—Polyurethanes
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J201/00—Adhesives based on unspecified macromolecular compounds
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
- H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
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- Dispersion Chemistry (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
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- Adhesives Or Adhesive Processes (AREA)
- Conductive Materials (AREA)
Abstract
The invention provides a conductive adhesive which has excellent thermal cycle performance, good reflow soldering performance and difficult stripping from a substrate. The above object is achieved by an electrically conductive adhesive which comprises a thermosetting resin and an electrically conductive filler, and which, after curing, has a Tg (TMA method) of 35 ℃ or higher, a tensile elastic modulus of 1.5GPa to 4GPa, a linear expansion coefficient of 250 ppm/DEG C or higher at-25 ℃ to 125 ℃, an hygroscopical expansion coefficient of 0.05% or lower when the humidity is increased from 55% to 75% at 20 ℃, and an hygroscopical expansion coefficient of 0.15% or lower when the humidity is increased from 55% to 95% at 20 ℃.
Description
Technical Field
The present invention relates to a conductive adhesive and a shielding film.
Background
As a method for eliminating noise in a printed circuit board, a method of retaining shielding performance by bonding a metal reinforcing plate such as SUS with a conductive adhesive is mainly used, and a method of using a shielding film having flexibility formed of a thin metal foil layer and a conductive adhesive is used for a bent portion of a flexible printed circuit board (FPC) or the like.
As conventional methods related thereto, for example, methods described in patent documents 1 and 2 are cited.
For such a conductive adhesive, a conductive adhesive excellent in characteristics when used in a thermal cycle test in which the following operations are repeatedly performed is sought: the ambient temperature is changed from a low temperature (for example, -45 ℃) to a high temperature (for example, 125 ℃), and then returned to the low temperature and thereafter changed to the high temperature. For example, when used in a mobile phone, the performance is required to be hardly deteriorated even if the heat cycle is repeated 1000 times.
In addition to the above-described thermal cycle properties, the conductive composition is required to have good reflow properties and to be difficult to peel from the substrate.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2003-298285
Patent document 2: japanese patent No. 5139156
However, the conductive adhesive for bonding the metal plate and the conductive adhesive for the shielding film have a problem that the resistance value is increased by humidity and temperature when the electronic device is used or by repeated use, and thus sufficient shielding performance cannot be exhibited. That is, there are problems as follows: strain is generated between the conductive adhesive and the metal plate due to temperature and humidity and repeated heat treatment, and the contact at the interface is lowered, and the resistance value is increased.
Disclosure of Invention
The present inventors have made extensive studies to solve the above-mentioned problems, and have found that the above-mentioned conductive adhesive which is excellent in thermal cyclability, excellent in reflow characteristics and difficult to peel from a substrate, and a shielding film comprising the conductive adhesive are provided, thereby completing the present invention.
The present invention is the following (1) to (5).
(1) An electrically conductive adhesive comprising a thermosetting resin and an electrically conductive filler and, after curing,
tg (TMA method) of 35 ℃ or higher,
the tensile elastic modulus is 1.5 GPa-4 GPa,
the linear expansion coefficient is more than 250 ppm/DEG C at-25-125 ℃,
the hygroexpansion coefficient is 0.05% or less when the humidity is increased from 55% to 75% at 20 ℃ and 0.15% or less when the humidity is increased from 55% to 95% at 20 ℃.
(2) The conductive adhesive according to the above (1), wherein the thermosetting resin comprises a polyurethane resin, a polyester resin and an epoxy resin.
(3) The conductive adhesive according to the above (1) or (2), wherein the conductive filler is silver-plated electrolytic copper powder having a dendritic structure.
(4) The conductive adhesive according to (3) above, wherein the electrolytic copper powder contains silver plating in an amount of 5 mass% or more and contains 45 mass% or more of the electrolytic copper powder.
(5) A shielding film comprising a layer formed from the conductive adhesive according to any one of (1) to (4) above on one main surface of an insulating layer formed from polyimide.
Effects of the invention
According to the present invention, a conductive adhesive which has excellent thermal cycle performance, good reflow performance, and is difficult to peel from a substrate, and a shielding film including the conductive adhesive can be provided.
Drawings
FIG. 1 is a schematic sectional view of an evaluation substrate [1] used in examples.
Detailed Description
The present invention will be explained.
The invention is a conductive adhesive comprising a thermosetting resin and a conductive filler, wherein after curing, the adhesive has a Tg (TMA method) of 35 ℃ or higher, a tensile elastic modulus of 1.5GPa to 4GPa, a linear expansion coefficient of 250 ppm/DEG C or higher at-25 ℃ to 125 ℃, an hygroscopical expansion coefficient of 0.05% or lower when the humidity is increased from 55% to 75% at 20 ℃, and an hygroscopic expansion coefficient of 0.15% or lower when the humidity is increased from 55% to 95% at 20 ℃.
Hereinafter, such a conductive adhesive is also referred to as "the adhesive of the present invention".
The present inventors have found that such a conductive adhesive has excellent thermal cycle characteristics, further has good reflow properties, and is difficult to peel from a substrate.
The TgTMA method), tensile modulus of elasticity, coefficient of linear expansion, and coefficient of hygroexpansivity in the adhesive of the present invention are values obtained by measurement according to the methods described in the following examples.
The adhesive of the present invention contains a thermosetting resin and a conductive filler. Here, the total content of the thermosetting resin and the conductive filler is preferably 70 mass% or more. The total content is more preferably 80% by mass or more, and still more preferably 95% by mass or more.
The adhesive of the present invention may contain additives contained in conventionally known adhesives, in addition to the thermosetting resin and the conductive filler. For example, it is possible to appropriately match: antioxidants such as hindered amines, hindered phenols, and phosphorus; flame retardants such as bromine, phosphorus, nitrogen, and metal hydroxide compounds; leveling agent, pigment, dye and other additives.
In the adhesive of the present invention, examples of the thermosetting resin include: epoxy resins, phenol resins, amino resins, alkyd resins, polyurethane resins, synthetic rubber amines, UV-curable acrylate resins, and the like, and one or more of them may be used.
The adhesive of the present invention more preferably contains a polyurethane resin, a polyester resin and an epoxy resin, and is further preferably a resin composition described below.
The resin composition consisted of: the polyurethane resin (a-1) contains a carboxyl group and has an acid value of 100 equivalents/106g is more than 1000 equivalent/106g or less, number average molecular weight of 5.0X 103Above and 1.0X 105A glass transition temperature of 30 ℃ to 80 ℃; polyester resin (a-2) having a number average molecular weight of 5.0X 103Above and 1.0X 105Below, the glass transition temperature is below 0 ℃; and an epoxy resin (b), wherein the content of the polyurethane resin (a-1) is 70 mass% or more and 95 mass% or less with respect to the total amount of the polyurethane resin (a-1) and the polyester resin (a-2), the content of the entire epoxy resin contained in the resin composition is 5 mass% or more and 30 mass% or less with respect to the total amount of the polyurethane resin (a-1) and the polyester resin (a-2), and the blending ratio of the epoxy resin (b) is 0.1 mass% or more and 20 mass% or less with respect to the entire epoxy resin contained in the resin composition.
In the resin composition, the polyurethane resin (a-1) is preferably obtained by reacting a polyester polyol (c), a compound (d) having one carboxyl group and two hydroxyl groups, and a polyisocyanate (e).
The resin composition preferably further contains an organic solvent.
The resin composition will be described in detail.
The resin composition comprises a specific polyurethane resin (a-1), a specific polyester resin (a-2) and an epoxy resin (b), and may further contain an organic solvent.
The number average molecular weight of the polyurethane resin (a-1) used in the resin composition was 5.0X 103Above and 1.0X 105The following. If the number average molecular weight of the polyurethane resin (a-1) is less than 5.0X 103The adhesion immediately after application is insufficient, and workability is deteriorated, and the flexibility is reduced, and the adhesiveness tends to be reduced. Of the polyurethane resin (a-1)Number average molecular weight of more than 1.0X 105The solution viscosity during coating is too high, and a uniform coating film may not be obtained. The lower limit of the number average molecular weight of the polyurethane resin (a-1) is preferably 8.0X 103More preferably 1.0X 104. Further, the upper limit value of the number average molecular weight of the polyurethane resin (a-1) is preferably 5.0X 104More preferably 3.5X 104。
The acid value of the polyurethane resin (a-1) used in the resin composition was 100 equivalents/106g is more than 1000 equivalent/106g is below. If the acid value of the polyurethane resin (a-1) is less than 100 equivalents/106g, the adhesiveness to the metal base material tends to be insufficient. In addition, crosslinking with the epoxy resin is insufficient, and heat resistance tends to decrease. If the acid value of the polyurethane resin (a-1) exceeds 1000 equivalents/106g, the storage stability of the varnish when dissolved in a solvent is lowered, and the crosslinking reaction of the adhesive sheet tends to proceed at room temperature, and a stable sheet life tends not to be obtained. In addition, crosslinking with the epoxy resin becomes too dense, and the adhesiveness tends to be lowered. The lower limit of the acid value of the polyurethane resin (a-1) is preferably 150 equivalents/106g, more preferably 200 equivalents/106g, more preferably 400 equivalent/106g. The upper limit of the acid value of the polyurethane resin (a-1) is preferably 900 equivalents/106g, more preferably 800 equivalents/106g, more preferably 700 equivalents/106g. Examples of the method for introducing the acid value include a method of copolymerizing a polyfunctional carboxylic acid having three or more functions with a polyester polyol constituting a polyurethane, and a method of using a diol containing a carboxylic acid as a chain extender.
The glass transition temperature of the polyurethane resin (a-1) used in the resin composition is 30 ℃ or higher and 80 ℃ or lower. When the glass transition temperature is less than 30 ℃, the adhesiveness under high temperature and high humidity tends to be insufficient. When the glass transition temperature exceeds 80 ℃, the adhesion to the substrate becomes insufficient, and the elastic modulus at room temperature becomes high, and the adhesion at room temperature tends to become insufficient. The lower limit of the glass transition temperature is preferably 35 ℃ and the lower limit of the glass transition temperature is more preferably 40 ℃. A preferred upper limit is 75 ℃ and a more preferred upper limit is 70 ℃.
The urethane resin (a-1) used in the resin composition preferably uses a polyester polyol (c), a polyisocyanate (e) and a chain extender as raw materials thereof.
The number average molecular weight of the polyester polyol (c) is preferably 2000 or more and 50000 or less, more preferably 6000 or more and 35000 or less. If the number average molecular weight is less than 2000, the number of urethane bonds in the molecule becomes too large, and the solder heat resistance is poor, and the adhesiveness is also reduced. On the other hand, when the number average molecular weight exceeds 50000, the distance between the crosslinking points of the epoxy resin becomes too long, and the solder heat resistance is deteriorated.
The aromatic acid is preferably 30 mol% or more, more preferably 45 mol% or more, and even more preferably 60 mol% or more, when the total amount of all acid components constituting the polyester polyol (c) is 100 mol%. When the aromatic acid content is less than 30 mol%, the cohesive strength of the coating film is weak, and the adhesive strength to various substrates is reduced.
As examples of the aromatic acid, there can be exemplified: aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 5-hydroxyisophthalic acid. Further, there may be mentioned: aromatic dicarboxylic acids having a sulfonic acid group or a sulfonate group such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2, 7-dicarboxylic acid, 5- (4-sulfophenoxy) isophthalic acid, and metal salts and ammonium salts thereof; aromatic oxycarboxylic acids such as p-hydroxybenzoic acid, p-hydroxypropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4, 4-bis (p-hydroxyphenyl) valeric acid. Among them, terephthalic acid, isophthalic acid, and mixtures thereof are particularly preferable in terms of improving the cohesive force of the coating film.
Further, as other acid components, there can be mentioned: alicyclic dicarboxylic acids such as 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, and 1, 2-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid.
On the other hand, the diol component is preferably composed of an aliphatic diol, an alicyclic diol, an aromatic-containing diol, an ether bond-containing diol, and the like, and examples of the aliphatic diol include: ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 2-methyl-1, 3-propanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 1, 9-nonanediol, 2-ethyl-2-butyl-1, 3-propanediol, neopentyl glycol hydroxypivalate, dimethylolheptane, 2, 4-trimethyl-1, 3-pentanediol and the like, and examples of alicyclic diols include: 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol A, and the like. Examples of the ether bond-containing diols include: diethylene glycol, triethylene glycol, dipropylene glycol, and further include: polyethylene glycol, polypropylene glycol, polytetramethylene glycol, an ethylene oxide adduct of neopentyl glycol, a propylene oxide adduct of neopentyl glycol, and the like. As examples of the aromatic group-containing diols, there can be exemplified: and diols obtained by adding one to several moles of ethylene oxide or propylene oxide to each of the two phenolic hydroxyl groups of bisphenols such as p-xylene glycol, m-xylene glycol, o-xylene glycol, 1, 4-xylene glycol, ethylene oxide adducts of 1, 4-xylene glycol, bisphenol a, ethylene oxide adducts of bisphenol a, and propylene oxide adducts.
Further, an oxycarboxylic acid compound having a hydroxyl group and a carboxyl group in a molecular structure can also be used as a polyester raw material, and examples thereof include: 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, 4-bis (p-hydroxyphenyl) pentanoic acid, and the like.
In order to introduce a branched skeleton into the polyester polyol (c) used in the resin composition, 0.1 mol% or more and 5 mol% or less of trifunctional or higher polycarboxylic acid and/or trifunctional or higher polyol are copolymerized, based on 100 mol% of all acid components or all diol components constituting the polyester polyol (c). Since the epoxy resin is blended in the resin composition, the terminal group of the resin (a-1), that is, the functional group capable of reacting with the crosslinking agent can be increased by introducing a branched skeleton, and a coating film having a high crosslinking density and a high strength can be obtained. Examples of the trifunctional or higher polycarboxylic acid exhibiting such an effect include: trimellitic acid, trimesic acid, ethylene glycol bis (trimellitic anhydride ester), glycerol tris (trimellitic anhydride ester), trimellitic anhydride, pyromellitic dianhydride (PMDA), Oxydiphthalic Dianhydride (ODPA), 3',4,4' -benzophenonetetracarboxylic dianhydride (BTDA), 3',4,4' -biphenyltetracarboxylic dianhydride (BPDA), 3',4,4' -diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'- (hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride (BSAA), and the like, while examples of trifunctional or higher polyhydric alcohols include: glycerol, trimethylolethane, trimethylolpropane, neopentyltetraol, etc. When a trifunctional or higher polycarboxylic acid and/or a trifunctional or higher polyol is used, it is preferable that the copolymerization is carried out in the range of 0.1 mol% or more and 5 mol% or less, preferably 0.1 mol% or more and 3 mol% or less, with respect to all of the acid components and all of the diol components, respectively, and if it exceeds 5 mol%, there is a case where mechanical properties such as elongation at break of the coating film are deteriorated, and there is a possibility that gelation may occur during polymerization.
In order to introduce a carboxyl group into the polyester polyol (c) used in the resin composition as needed, acid addition may be performed in a range of 0.1 mol% or more and 10 mol% or less. When a monocarboxylic acid, a dicarboxylic acid or a polyfunctional carboxylic acid compound is used for the acid addition, the molecular weight is reduced by the ester exchange, and therefore, an acid anhydride is preferably used. As the acid anhydride, there can be used: succinic anhydride, maleic anhydride, phthalic anhydride, 2, 5-norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic dianhydride (PMDA), Oxydiphthalic Dianhydride (ODPA), 3',4,4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 3',4,4' -biphenyl tetracarboxylic dianhydride (BPDA), 3',4,4' -diphenylsulfone tetracarboxylic dianhydride (DSDA), 4,4'- (hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride (BSAA), and the like. When the total acid content of the polyester polyol (c) used in the present invention is 100 mol%, if 10 mol% or more of acid is added, gelation may occur, and depolymerization of the polyester may occur to lower the resin molecular weight. Examples of the method of performing acid addition include a method of directly performing polycondensation of a polyester in a bulk state and a method of solubilizing and adding a polyester. The reaction rate in the bulk state is high, but when a large amount of addition is performed, gelation may occur and the reaction is at a high temperature, so that it is necessary to take care to prevent oxidation by blocking oxygen. On the other hand, although the addition reaction in the solution state is slow, a large amount of carboxyl groups can be stably introduced.
The polyisocyanate (e) used for producing the polyurethane resin (a-1) used in the resin composition may be one of diisocyanate, dimer thereof (uretdione), trimer thereof (isocyanurate, triol adduct, biuret), etc., or a mixture of two or more thereof. Examples of the diisocyanate component include: 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, 3 '-dimethoxy-4, 4' -biphenyl diisocyanate, 1, 5-naphthalene diisocyanate, 2, 6-naphthalene diisocyanate, diphenyl ether-4, 4 '-diisocyanate, 1, 5-xylylene diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, 1, 4-bis (isocyanatomethyl) cyclohexane, 4' -diisocyanate cyclohexylmethane, isophorone diisocyanate, dimer acid diisocyanate, toluene diisocyanate, Norbornene diisocyanate and the like are preferably aliphatic and alicyclic diisocyanates in view of yellowing. Further, hexamethylene diisocyanate and isophorone diisocyanate are particularly preferable for the reasons of easy availability and economy.
When the polyurethane resin (a-1) used in the resin composition is produced, a chain extender may be used as needed. As the chain extender, there can be mentioned: and compounds (d) having one carboxylic acid and two hydroxyl groups, such as low molecular weight diols, dimethylolpropionic acid, and dimethylolbutyric acid, which are described as components of the polyester polyol (c). Among them, dimethylolbutanoic acid is preferable in terms of ease of introduction of an acid value and solubility in general-purpose solvents. Further, trimethylolpropane is also preferably used in terms of ease of introduction of hydroxyl groups.
As a method for producing the urethane resin (a-1) used in the resin composition, the polyester polyol (c), the polyisocyanate (e), and if necessary, the chain extender may be added to a reaction vessel at once, or they may be added in portions. In any case, the reaction is carried out under the condition that the ratio of isocyanate groups/hydroxyl groups is 1 or less with respect to the polyester polyol, the total hydroxyl value of the chain extender, and the total isocyanate groups of the polyisocyanate in the system. The reaction can be carried out in the presence or absence of a solvent which is inert to the isocyanate group. Examples of the solvent include: ester solvents (such as ethyl acetate, butyl acetate, and ethyl butyrate), ether solvents (such as dioxane, tetrahydrofuran, and diethyl ether), ketone solvents (such as cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone), aromatic hydrocarbon solvents (such as benzene, toluene, and xylene), and mixed solvents thereof are preferably ethyl acetate and methyl ethyl ketone from the viewpoint of reducing environmental load. The reaction apparatus is not limited to a reaction tank equipped with a stirring device, and a mixing and kneading device such as a kneader or a twin-screw extruder may be used.
In order to promote the polyurethane reaction, catalysts used in the usual polyurethane reaction may be used, for example: tin catalysts (trimethyltin laurate, dimethyltin dilaurate, trimethyltin hydroxide, dimethyltin dihydroxide, stannous octoate, etc.), lead catalysts (lead oleate, lead 2-ethylhexanoate, etc.), amine catalysts (triethylamine, tributylamine, morpholine, diazabicyclooctane, diazabicycloundecene, etc.), etc., and from the viewpoint of harmfulness, amine catalysts are preferred.
The number average molecular weight of the polyester resin (a-2) used in the resin composition is preferably 5.0X 103Above and 1.0X 105The following. If the number average molecular weight of the polyester resin (a-2) is less than 5.0X 103The mechanical strength of the adhesive tends to be lowered, and the heat resistance and adhesiveness tend to be lowered, and when the number average molecular weight exceeds 1.0X 105In some cases, the solution viscosity during coating is too high, and a uniform coating film cannot be obtained. The lower limit of the number average molecular weight of the polyester resin (a-2) is preferably 8.0X 103More preferably 1.0X 104. Further, the upper limit value of the number average molecular weight of the polyester resin (a-2) is preferably 5.0X 104More preferably 3.5X 104。
The polyester resin (a-2) used in the resin composition has a glass transition temperature of 0 ℃ or lower. When the glass transition temperature exceeds 0 ℃, the adhesive sheet tends to become hard and brittle, and the adhesive sheet may crack during production to deteriorate workability. Further, the adhesive tends to be hardened and the adhesiveness tends to be insufficient. The glass transition temperature is preferably-5 ℃ or lower, more preferably-10 ℃ or lower.
As the acid component and the diol component used for the polyester resin (a-2) in the resin composition, the same compounds as those listed as the acid component and the diol component used for the polyester polyol (c) can be preferably used. As the method for adjusting the glass transition temperature of the polyester resin (a-2) to 0 ℃ or lower, there are a method of copolymerizing an aliphatic dicarboxylic acid, a method of copolymerizing a long-chain diol, a method of copolymerizing a polyalkylene glycol, a method of copolymerizing a lactone, and the like.
Examples of aliphatic dicarboxylic acids include: succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and the like. Examples of long-chain diols include: nonanediol, decanediol, dimer acid diol, and the like. Examples of polyalkyl glycols include: diethylene glycol, triethylene glycol, dipropylene glycol, and further include: polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Examples of lactones are: beta-propiolactone, gamma-butyrolactone, -valerolactone, -caprolactone and the like. Among the lactones, caprolactone is preferable for the reasons of easy acquisition and economy, and it is preferable that the lactone monomer is put into the polyester resin in a bulk state after polycondensation and subjected to ring-opening polymerization as a copolymerization method.
In the resin composition, the mixing ratio of the polyurethane resin (a-1) and the polyester resin (a-2) is 95/5-70/30, preferably 95/5-80/20, and more preferably 93/7-85/15 by mass ratio. When the amount of the polyester resin (a-2) is more than 30% by mass, the adhesive properties at room temperature, high temperature and high humidity tend to be lowered, and when the amount is less than 5% by mass, the adhesive sheet tends to be hardened and brittle, and the adhesive sheet tends to crack during production to lower workability.
The epoxy resin (b) contained in the resin composition is not particularly limited as long as it contains at least two or more epoxy groups in a molecule.
Can be exemplified by: bisphenol type epoxy resins such as bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, novolac type epoxy resin such as bisphenol a novolac type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, dicyclopentadiene type epoxy resin, trifunctional (or tetrafunctional) glycidyl amide, diglycidyl ether compound of naphthalene diol, diglycidyl ether compound of phenol, diglycidyl ether compound of alcohol, alkyl substitution products thereof, hydride thereof, and the like, and dicyclopentadiene type epoxy resin having a dicyclopentadiene skeleton is more preferably used.
When the dicyclopentadiene type epoxy resin is used, the moisture absorption rate of the cured coating film is extremely small, and the crosslinking density of the cured coating film can be reduced to relax the stress at the time of peeling from the substrate, so that the effect of further improving the adhesion under high humidity can be obtained.
The epoxy resin may be used alone or in combination of two or more.
As other epoxy resins, there may be mentioned: glycidyl esters such as glycidyl hexahydrophthalate and glycidyl dimer acid; or alicyclic or aliphatic epoxides such as 3, 4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, epoxidized soybean oil, and the like.
The amount of the epoxy resin to be incorporated in the resin composition as a whole is 5 to 30 parts by mass based on 100 parts by mass of the total of the urethane resin (a-1) and the polyester resin (a-2). If the amount of the epoxy resin to be blended as a whole is less than 5 parts by mass relative to 100 parts by mass of the total of the urethane resin (a-1) and the polyester resin (a-2), crosslinking tends to be insufficient and heat resistance tends to be lowered, and if it exceeds 30 parts by mass, a large amount of unreacted epoxy resin remains and heat resistance and moisture resistance tend to be lowered.
A curing catalyst may be used in the curing reaction of the epoxy resin (b) for the resin composition. Examples thereof include: imidazole compounds such as 2-methylimidazole, 1, 2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole and 1-cyanoethyl-2-ethyl-4-methylimidazole; tertiary amines such as triethylamine, triethylenediamine, N' -methyl-N- (2-dimethylaminoethyl) piperazine, 1, 8-diazabicyclo (5,4,0) -7-undecene, 1, 5-diazabicyclo (4,3,0) -5-nonene, and 6-dibutylamino-1, 8-diazabicyclo (5,4,0) -7-undecene; and compounds in which these tertiary amines are converted into amine salts by phenol, octanoic acid, tetraphenyl onium borate, or the like; cationic catalysts such as triallylsulfonium hexafluoroantimonate and diallylsulfonium hexafluoroantimonate; triphenylphosphine, and the like. Among them, tertiary amines such as 1, 8-diazabicyclo (5,4,0) -7-undecene, 1, 5-diazabicyclo (4,3,0) -5-nonene, 6-dibutylamino-1, 8-diazabicyclo (5,4,0) -7-undecene and the like, and compounds in which these tertiary amines are converted into amine salts by phenol, octanoic acid, tetraphenylboronic acid onium salt and the like are preferable in terms of thermosetting property, heat resistance, adhesion to metal, and storage stability after blending. The amount to be blended in this case is preferably 0.01 to 1.0 parts by mass per 100 parts by mass of the urethane resin (a-1). Within this range, the effect of the reaction of the urethane resin (a-1) with the epoxy compound can be further increased, and a stable adhesive property can be obtained.
The adhesive of the present invention is a conductive adhesive comprising the above-mentioned thermosetting resin (preferably the above-mentioned resin composition) and a conductive filler, and after curing, has a specific Tg (TMA method), a specific tensile elastic modulus, a specific linear expansion coefficient, and a specific moisture absorption expansion coefficient.
In the adhesive of the present invention, the conductive filler is not particularly limited, and may be copper powder, silver powder, or gold powder, and electrolytic copper powder is preferable.
The shape and the like of the conductive filler are also not particularly limited, and examples thereof include a columnar shape and a scaly shape, and a dendritic structure (dendritic structure) is preferable.
The conductive filler is more preferably electrolytic copper powder having a dendritic structure (dendritic structure) which is silver-plated.
The content of the conductive filler contained in the adhesive of the present invention is not particularly limited, and is preferably 10 to 80 mass%. When the amount is more than 80% by mass, the adhesiveness tends to be lowered, and when the amount is less than 10% by mass, the conductivity tends to be lowered.
The conductive filler is preferably electrolytic copper powder having a silver plating content of 5 mass% or more. More preferably, the electrolytic copper powder contains 45 mass% or more.
The present invention includes a shielding film having a layer formed of the adhesive of the present invention on one main surface of an insulating layer formed of polyimide, in addition to the adhesive of the present invention.
Hereinafter, such a shielding film is also referred to as "the film of the present invention".
The layer formed from the adhesive of the present invention has shielding properties, and thus can be used as an electromagnetic wave shielding film for a flexible printed circuit board.
The film of the present invention has a layer formed of the adhesive of the present invention on one main surface of an insulating layer formed of polyimide.
As the polyimide, a film obtained by coating a polyamide-imide solution composed of an acid anhydride and a diamine, drying, and cyclizing is generally used, but a black polyimide is preferably used in terms of appearance. The method for producing black is not particularly limited, and carbon black is preferably mixed with a polyamideimide solution to form a film.
The film of the present invention may have a layer formed of the adhesive of the present invention on one main surface of an insulating layer formed of polyimide, and further have a protective film (release film) thereon. In this case, a layer formed from the adhesive of the present invention is sandwiched between a protective film (release film) and an insulating layer.
Examples of the protective film include: PET film alone, and laminates of PET or OPP with paper as a base material. When the adhesive layer is adhered to the substrate, a release agent may be applied thereto as needed.
The film of the present invention can be obtained by applying the adhesive of the present invention to an insulating layer formed of polyimide and drying the same in accordance with a conventional method. Further, when the protective film is attached to the layer formed of the pressure-sensitive adhesive of the present invention after drying, the protective film can be wound up without causing strike-through to the base material, and the handling property is excellent.
In the film of the present invention, the thickness of the layer formed by the binder of the present invention is not particularly limited, but is preferably 1 to 500. mu.m, more preferably 10 to 300. mu.m, and still more preferably 20 to 100. mu.m.
Examples
Hereinafter, examples of the present invention and comparative examples will be described.
Polyester urethane resin a, polyester urethane resin B and polyester resin C were obtained by the following synthesis methods. Then, the number average molecular weight, glass transition temperature, and acid value were determined. The measurement method for these measurement evaluation items will be described below.
< acid number >
0.2g of the sample was dissolved in 20ml of chloroform, and the solution was titrated with 0.1N ethanol potassium hydroxide solution using phenolphthalein as an indicator to calculate the resin content per 106Equivalent of g (equivalent/10)6g)。
< glass transition temperature >
10mg of the measurement sample was placed in an aluminum pot, the pot was sealed with a lid, and the temperature was measured at a temperature rise rate of 20 ℃/min using a Differential Scanning Calorimeter (DSC) DSC-200 manufactured by Seiko Instruments, and the glass transition temperature was determined as the intersection of a straight line extending from a reference line on the low temperature side toward the high temperature side and a tangent drawn at a point where the slope of the curve in the stepwise change portion of the glass transition became maximum.
< number average molecular weight >
The molecular weight was measured by gel permeation chromatography using a differential refractometer as a detector, using tetrahydrofuran as a sample for measurement and tetrahydrofuran as a mobile phase, by dissolving and/or diluting the sample with tetrahydrofuran so that the resin concentration became about 0.5 mass%, and filtering the solution with a polytetrafluoroethylene membrane filter having a pore size of 0.5 μm. The flow rate was set to 1 mL/min and the column temperature was set to 30 ℃. KF-802, 804L and 806L manufactured by Showa electrician were used for the columns. Monodisperse polystyrene was used for the molecular weight standards.
< Synthesis of polyester polyurethane resin A >
50 parts by mass of terephthalic acid, 49 parts by mass of isophthalic acid, 1 part by mass of trimellitic anhydride, 83 parts by mass of 2-methyl-1, 3-propanediol, and 17 parts by mass of 1, 4-butanediol were added to a reaction tank equipped with a stirrer, a thermometer, and a cooler for outflow, and the temperature was gradually raised to 230 ℃ over 4 hours, and esterification was carried out while removing distilled water to the outside of the system. After the esterification reaction was completed, the initial polymerization was carried out under reduced pressure to 10mmHg for 30 minutes, and the temperature was raised to 240 ℃ and further the post polymerization was carried out under 1mmHg or less for 30 minutes. Thereafter, the pressure was returned to normal pressure with nitrogen, and 1 part by mass of trimellitic anhydride was charged and reacted at 220 ℃ for 1 hour, thereby obtaining a polyester resin.
650 parts by mass of the polyester resin obtained in this manner was added to a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a distillation tube, and further 650 parts by mass of toluene was added and dissolved, and then 413 parts by mass of toluene was distilled to dehydrate the reaction system by azeotropic distillation of toluene/water. After cooling to 60 ℃, 29.3 parts by mass of 2, 2-dimethylolbutyric acid (DMBA) and 237 parts by mass of methyl ethyl ketone were added. After the DMBA was dissolved, 30.6 parts by mass of hexamethylene diisocyanate was added, and further 0.03 part by mass of Diazabicycloundecene (DBU) as a reaction catalyst was added, and a reaction was performed at 80 ℃ for 7 hours, and then 444 parts by mass of methyl ethyl ketone and 148 parts by mass of toluene were added to adjust the solid content concentration to 40% by weight, thereby obtaining a solution containing polyester polyurethane resin a. The measurement was performed according to the above-mentioned measurement evaluation items using a film obtained by drying a solution containing the polyester urethane resin a at 120 ℃ for 1 hour to remove the solvent.
As a result, the acid value: 360 equivalent/106g. Glass transition temperature: 40 ℃ and number average molecular weight: 18000.
< Synthesis of polyester polyurethane resin B >
A reaction tank equipped with a stirrer, a thermometer, and a cooler for outflow was charged with 29 parts by mass of terephthalic acid, 70 parts by mass of isophthalic acid, 1 part by mass of trimellitic anhydride, 30 parts by mass of 2-methyl-1, 3-propanediol, and 70 parts by mass of 1, 4-butanediol, and the temperature was gradually raised to 230 ℃ over 4 hours, and esterification was carried out while removing distilled water from the system. After the esterification reaction was completed, the initial polymerization was carried out under reduced pressure to 10mmHg for 30 minutes, and the temperature was raised to 240 ℃ and further the post polymerization was carried out under 1mmHg or less for 30 minutes. Thereafter, the pressure was returned to normal pressure with nitrogen, and 1 part by mass of trimellitic anhydride was charged and reacted at 220 ℃ for 1 hour, thereby obtaining a polyester resin.
650 parts by mass of the polyester resin obtained in this manner was added to a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a distillation tube, and 650 parts by mass of toluene was further added and dissolved, and then 413 parts by mass of toluene was distilled to dehydrate the reaction system by azeotropic distillation of toluene/water. After cooling to 60 ℃, 29.3 parts by mass of 2, 2-dimethylolbutyric acid (DMBA) and 237 parts by mass of methyl ethyl ketone were added. After the DMBA was dissolved, 53.4 parts by mass of hexamethylene diisocyanate and further 0.03 parts by mass of Diazabicycloundecene (DBU) as a reaction catalyst were added, and the mixture was reacted at 80 ℃ for 7 hours, and then 444 parts by mass of methyl ethyl ketone and 148 parts by mass of toluene were added to adjust the solid content concentration to 40% by weight, thereby obtaining a solution containing polyester urethane resin B. The measurement was performed according to the above-mentioned measurement evaluation items using a film obtained by drying a solution containing the polyester urethane resin B at 120 ℃ for 1 hour to remove the solvent.
As a result, the acid value: 630 eq/106g. Glass transition temperature: 10 ℃ and number average molecular weight: 13000.
< Synthesis of polyester resin C >
Into a reaction tank equipped with a stirrer, a thermometer, and a cooler for outflow, 49 parts by mass of terephthalic acid, 49 parts by mass of isophthalic acid, 2 parts by mass of trimellitic anhydride, 50 parts by mass of ethylene glycol, and 50 parts by mass of neopentyl glycol were added, and the temperature was gradually raised to 250 ℃ over 4 hours, and esterification was carried out while removing distilled water to the outside of the system. After the esterification reaction was completed, the initial polymerization was carried out under reduced pressure to 10mmHg for 30 minutes, and the temperature was raised to 250 ℃ and further the post polymerization was carried out under 1mmHg or less for 30 minutes. Thereafter, the pressure was returned to normal pressure with nitrogen, and 140 parts by mass of caprolactone was charged and reacted at 200 ℃ for 1 hour to obtain a polyester resin C. Then, the solution containing the polyester resin C was dried at 120 ℃ for 1 hour to remove the solvent, and the film was used to perform the measurement according to the above-described measurement evaluation items.
As a result, the acid value: less than 40 equivalents/106g. Glass transition temperature: -18 ℃, number average molecular weight: 28000.
< epoxy resin D >
As the epoxy resin D, YDCN703 (o-cresol novolac type epoxy resin) manufactured by eastern chemical company was prepared.
< epoxy resin E >
As the epoxy resin E, HP7200-H (dicyclopentadiene type epoxy resin) manufactured by Dainippon ink industries, Ltd was prepared.
< electrolytic copper powder F >
ACAX-2 (manufactured by Mitsui Metal mining Co., Ltd.) was prepared as a 10% silver-plated product as electrolytic copper powder F.
< electrolytic copper powder G >
ACAX-2 (manufactured by Mitsui Metal mining Co., Ltd.) was prepared as a 7% silver-plated product as hailylysis copper powder G.
< examples 1 to 5>
The above polyester urethane resin a, polyester urethane resin B, polyester resin C, epoxy resin D, epoxy resin E, electrolytic copper powder F and electrolytic copper powder G were mixed in the proportions (parts by mass) shown in table 1 below. Specifically, components other than electrolytic copper powder F, G were dissolved in a mixed solvent obtained by mixing methyl ethyl ketone and toluene in a mass ratio of 1:1, and electrolytic copper powder F or electrolytic copper powder G was added thereto and dispersed with stirring to obtain a conductive adhesive solution.
TABLE 1
TABLE 1
| Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | |
| Polyester polyurethane resin A | 30 | 30 | 30 | 30 | 15 |
| Polyester polyurethane resin B | 15 | ||||
| Polyester resin C | 5 | 5 | 5 | 5 | 5 |
| Epoxy resin D | 2.5 | ||||
| Epoxy resin E | 5 | 5 | 5 | 5 | 2.5 |
| Electrolytic copper powder F (silver plating 10%) | 60 | 45 | 75 | 60 | |
| Electrolytic copper powder G (silver plating 7%) | 60 |
Next, three commercially available conductive adhesives were prepared as comparative examples to the conductive adhesive solutions of examples 1 to 5 shown in table 1. The conductive adhesive solutions of comparative examples 1,2 and 3 were used. Further, a composition obtained by removing electrolytic copper powder F from the composition of example 1, that is, polyester urethane resin a, polyester resin C and epoxy resin E were mixed at a mass ratio of 30:5:5 was prepared as a conductive adhesive solution of comparative example 4.
Next, each of the conductive adhesive solutions of examples 1 to 5 and each of the conductive adhesive solutions of comparative examples 1 to 4 shown in table 1 was applied to one side of the PET film subjected to the single-sided release treatment so that the thickness after drying was 60 μm, and dried, thereby obtaining an evaluation film in which a layer (adhesive layer) formed of the conductive adhesive solution was attached to the PET film.
Then, the pressure-sensitive adhesive layer was peeled off from the film for evaluation, sandwiched between two Teflon plates, vacuum-pressed at 180 ℃ for 200 seconds (2MPa), and then placed on N2Curing was carried out in an oven at 140 ℃ for 4 hours.
The treated pressure-sensitive adhesive layer obtained in this way was subjected to Tg measurement, linear expansion coefficient measurement, tensile elastic modulus measurement, and moisture absorption expansion coefficient measurement by the following methods.
< measurement of Tg, measurement of coefficient of linear expansion >
The glass transition temperature was determined using a thermomechanical analyzer (TMA: Thermal Mechanical Analysis).
The coefficient of linear thermal expansion (CTE) was measured by setting the sample length to 15mm, fixing the sample at a fixed tensile load of 0.05N, and raising the temperature at a rate of 5 ℃/min from room temperature. The film was measured in the TD direction.
< determination of tensile elastic modulus >
Measured according to JIS-K6251. The sample width was set to 10mm, the gauge length was set to 100mm, and the drawing speed was set to 50 mm/min.
< hygroexpansion Rate >
The sample size was MD200 × TD250mm, and 20-well measurement was performed using an optical noncontact three-dimensional measuring instrument as a measuring device. Here, the openings are according to IPCTM6502.2.4. Humidity control conditions were set to 20 ℃, 55% RH and 24 hours, and humidification conditions were set to 20 ℃, 75% RH and 24 hours. That is, the humidity was increased from 55% to 75% at 20 ℃ and the hygroexpansion after the lapse of 24 hours was measured. The obtained hygroexpansion coefficient is referred to as "hygroexpansion coefficient a".
The hygroexpansivity was also measured when the humidification conditions were changed to 20 ℃, 95% RH, and 24 hours, compared to the case where the hygroexpansivity a was obtained. That is, the humidity was increased from 55% to 95% at 20 ℃ and the hygroexpansion after the lapse of 24 hours was measured. The obtained hygroexpansion coefficient is referred to as "hygroexpansion coefficient B".
The Tg measurement, the linear expansion coefficient measurement, the tensile elastic modulus measurement, and the hygroexpansivity of the treated adhesive layer obtained as described above are shown in table 2.
Next, an evaluation substrate [ l ] shown in fig. 1 was prepared from the evaluation films obtained as described above and made of the conductive adhesive solutions of examples 1 to 5 and the conductive adhesive solutions of comparative examples 1 to 4 shown in table 1. The manufacturing method will be explained.
First, the adhesive layer 3 was peeled from the evaluation films obtained as described above and made of the conductive adhesive solutions of examples 1 to 5 and the conductive adhesive solutions of comparative examples 1 to 4 shown in table 1, and placed on the main surface of the Ni-SUS plate 1. Here, the Ni-SUS plate 3 was made of SUS304 (thickness: 0.12mm) after nickel plating. Then, vacuum pressing (2MPa) was performed at 100 ℃ for 10 seconds using a vacuum press. The obtained Ni-SUS plate was attached with an adhesive layer as the SUS auxiliary material 5.
Subsequently, the SUS auxiliary material 5 was bonded to the FPC13 by vacuum pressing (2MPa) at 180 ℃ for 200 seconds using a vacuum press. The FPC13 is formed by forming a circuit 9 formed by gold plating on a copper foil 11 and further forming a polyimide cover film 7 covering a part of them. Here, the opening area of the portion exposed from the cover film 7 in the circuit 9 formed by gold plating was 4mm2。
Then, a product obtained by bonding SUS auxiliary material 5 and FPC13 was placed on N2In an oven, curing was carried out at 140 ℃ for 4 hours, and then reflow treatment was carried out at a maximum temperature of 260 ℃ for 10 seconds to obtain an evaluation substrate [1] shown in FIG. 1](10)。
The evaluation substrate [1] obtained in this manner was measured for initial resistance value, resistance value after moisture absorption, resistance value after thermal cycle, and resistance value after reflow soldering by the following methods.
< initial resistance value >
The resistance value was measured between the two measurement units shown in FIG. 1. The results are shown in Table 2.
In table 2, in addition to the initial resistance value, the resistance value after moisture absorption, the resistance value after heat cycle, and the resistance value after reflow soldering were also expressed as "excellent" when the resistance value was less than 100m Ω, as "o" when the resistance value was 100m Ω or more and less than 500m Ω, and as "x" when the resistance value was 500m Ω or more.
< resistance value after moisture absorption >
After the evaluation substrate [1] was held at 85 ℃ and 85% RH for 500 hours, the resistance value was measured by the same method as in the case of the initial resistance value. The results are shown in Table 2.
< resistance value after thermal cycle >
The evaluation substrate [1] was kept in an atmosphere at-45 ℃ for 30 minutes and then in an atmosphere at 125 ℃ for 30 minutes as one cycle, and this treatment was repeated 1000 cycles, and then the resistance value was measured by the same method as in the case of the above initial resistance value. The results are shown in Table 2.
< resistance value after reflow soldering >
After four treatments of holding the evaluation substrate [ l ] in an ambient gas at a maximum temperature of 260 ℃ for 10 seconds were repeated, the resistance value was measured by the same method as in the case of the above-described initial resistance value. The results are shown in Table 2.
TABLE 2
TABLE 2
Next, the shielding performance was measured. The description will be specifically made.
Using the adhesive layers in example 1 and comparative example 1 described above, an evaluation substrate [2] was obtained in which the portion of the Ni — SUS plate in the evaluation substrate [1] shown in fig. 1 was changed to a black polyimide film (film made of polyimide containing carbon black). The evaluation substrate [2] can be produced by the same method as the evaluation substrate [1 ].
Then, the shielding performance was measured for each of the evaluation substrates [2] including the adhesive layers of example 1 and comparative example 1.
For shielding performance, a signal transmitter is used: anritsu Signal GENERATOR MG3601A, spectrum analyzer: agilent E4403B, amplifier: a device owned by KEC (the general community of law, the kansai electronic industry joy center) of Anritsu PRE AMPLIFIER MH 648A.
As a result, there was no difference in barrier performance between the respective evaluation substrates [2] including the pressure-sensitive adhesive layers of example 1 and comparative example 1.
Claims (4)
1. An electrically conductive adhesive comprising a thermosetting resin and an electrically conductive filler,
the thermosetting resin consists of: a urethane resin containing a carboxyl group and having an acid value of 100 equivalents/106g is more than 1000 equivalent/106g or less, number average molecular weight of 5.0X 103Above and 1.0X 105A glass transition temperature of 30 ℃ to 80 ℃; polyester resin having a number average molecular weight of 5.0X 103Above and 1.0X 105Below, the glass transition temperature is below 0 ℃; and an epoxy resin (b), wherein the content of the polyurethane resin is 70 to 95 mass% based on the total of the polyurethane resin and the polyester resin, the content of the entire epoxy resin contained in the resin composition is 5 to 30 mass% based on the total of the polyurethane resin and the polyester resin, and the blending ratio of the epoxy resin is 0.1 to 20 mass% based on the entire epoxy resin contained in the resin composition,
after the electrically conductive adhesive is cured,
tg (TMA method) of 35 ℃ or higher,
the tensile elastic modulus is 1.5 GPa-4 GPa,
the linear expansion coefficient is more than 250 ppm/DEG C at-25-125 ℃,
the hygroexpansion coefficient is 0.05% or less when the humidity is increased from 55% to 75% at 20 ℃ and 0.15% or less when the humidity is increased from 55% to 95% at 20 ℃.
2. The conductive adhesive according to claim 1, wherein the conductive filler is silver-plated electrolytic copper powder having a dendritic structure.
3. The conductive adhesive according to claim 2, wherein the electrolytic copper powder contains silver plating in an amount of 5 mass% or more and contains 45 mass% or more of the electrolytic copper powder.
4. A shielding film characterized by having a layer formed of the conductive adhesive according to any one of claims 1 to 3 on one main surface of an insulating layer formed of polyimide.
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| JP7256618B2 (en) * | 2018-08-29 | 2023-04-12 | タツタ電線株式会社 | Electromagnetic wave shielding film with transfer film, method for producing electromagnetic wave shielding film with transfer film, and method for producing shield printed wiring board |
| JP2020045463A (en) * | 2018-09-21 | 2020-03-26 | 株式会社タムラ製作所 | Anisotropic conductive adhesive and method of manufacturing electronic substrate using the same |
| TW202043407A (en) * | 2019-03-04 | 2020-12-01 | 日商拓自達電線股份有限公司 | Conductive adhesive composition |
| TWI803745B (en) | 2020-04-22 | 2023-06-01 | 財團法人紡織產業綜合研究所 | Conductive textile and method for fabricating the same |
| JPWO2022123999A1 (en) * | 2020-12-10 | 2022-06-16 | ||
| WO2022196270A1 (en) * | 2021-03-19 | 2022-09-22 | 富士フイルム株式会社 | Three-dimensional conductive film for transparent heaters, and method for producing three-dimensional conductive film for transparent heaters |
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| JP2012092247A (en) * | 2010-10-28 | 2012-05-17 | Showa Denko Kk | Liquid-form curable composition |
| CN104797360A (en) * | 2012-10-03 | 2015-07-22 | 户田工业株式会社 | Silver hybrid copper powder, method for producing same, conductive paste containing silver hybrid copper powder, conductive adhesive, conductive film and electrical circuit |
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| JPH10173303A (en) * | 1996-12-12 | 1998-06-26 | Nitto Denko Corp | Printed circuit board |
| JP3371894B2 (en) * | 1999-09-17 | 2003-01-27 | ソニーケミカル株式会社 | Connecting material |
| KR102218936B1 (en) * | 2014-05-28 | 2021-02-23 | 도요보 가부시키가이샤 | Adhesive composition using polyamide-imide resin |
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- 2017-04-25 TW TW106113746A patent/TWI731068B/en active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012092247A (en) * | 2010-10-28 | 2012-05-17 | Showa Denko Kk | Liquid-form curable composition |
| CN104797360A (en) * | 2012-10-03 | 2015-07-22 | 户田工业株式会社 | Silver hybrid copper powder, method for producing same, conductive paste containing silver hybrid copper powder, conductive adhesive, conductive film and electrical circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2017195400A1 (en) | 2019-05-23 |
| CN108026420A (en) | 2018-05-11 |
| WO2017195400A1 (en) | 2017-11-16 |
| TWI731068B (en) | 2021-06-21 |
| JP6719550B2 (en) | 2020-07-08 |
| TW201809187A (en) | 2018-03-16 |
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