JP7435001B2 - Anisotropic conductive adhesive film, connected structure and manufacturing method thereof - Google Patents

Description

The present invention relates to an anisotropically conductive adhesive film, a connected structure, and a method for manufacturing the same.

Conventionally, liquid crystal display devices, organic EL panels, and the like have been used as various display means for televisions, PC monitors, mobile phones, smart phones, portable game machines, tablet terminals, wearable terminals, vehicle monitors, and the like. In recent years, in such display devices, so-called COG (chip on glass), in which a driving IC is directly mounted on a glass substrate of a display panel, has been adopted from the viewpoints of finer pitch, lighter weight, and thinner design.

For example, in a liquid crystal display panel that uses the COG mounting method, a plurality of transparent electrodes made of ITO (indium tin oxide), etc. are formed on a transparent substrate such as a glass substrate, and liquid crystal driving ICs, etc. are mounted on these transparent electrodes. semiconductor elements are connected. For example, when using a liquid crystal driving IC, a plurality of electrode terminals corresponding to transparent electrodes are formed on its mounting surface, and the liquid crystal driving IC is thermocompression bonded onto a transparent substrate via an anisotropic conductive adhesive film. As a result, the electrode terminal and the transparent electrode are connected to obtain a connected structure.

The anisotropically conductive adhesive film is made into a film by blending conductive particles into an adhesive component. When two conductors are heat-pressed and bonded via an anisotropic conductive adhesive film, electrical continuity between the conductors is established by the conductive particles, and mechanical connection between the conductors is maintained by the adhesive component. As the adhesive component, a thermosetting binder resin, a photocuring binder resin, or a binder resin that is cured by a combination of light and heat is used.

In recent years, displays with curved surfaces (flexible displays) have been proposed, and in some flexible displays that have been put into practical use, flexible plastic substrates are used instead of glass as base materials, so various types of driving ICs, etc. Electronic components will also be mounted on plastic substrates. As such a mounting method, COP (chip on plastic) using an anisotropic conductive adhesive film is being considered (for example, Patent Document 1).

JP2016-54288A

By the way, the plastic substrate used in COP is different from the glass substrate used in COG in terms of thermal properties and mechanical properties. Therefore, according to the studies of the present inventors, when the anisotropically conductive adhesive film used for COG is used as is for COP, the bonding strength, peel strength, and connection resistance (particularly high temperature and Satisfactory characteristics may not be obtained in terms of connection resistance (after being placed in a humid environment).

Therefore, the present invention provides an anisotropic connection structure that can provide an excellent bonding strength, peel strength, and connection resistance after being placed in a high temperature and high humidity environment when connecting electronic components having plastic substrates. The purpose of the present invention is to provide a conductive adhesive film.

One aspect of the present invention is an anisotropically conductive adhesive film containing a thermosetting adhesive component and conductive particles, the anisotropically conductive adhesive film being thermoset at 200°C for 1 hour. The cured product is an anisotropically conductive adhesive film having a storage modulus of 0.7 GPa to 1.5 GPa at 40°C.

Another aspect of the present invention includes a plastic substrate, a first electronic member having an electrode provided on the plastic substrate, a second electronic member, and a first electronic member and a second electronic member. and a connecting member electrically connected to each other, the connecting member being a cured product of the above-mentioned anisotropically conductive adhesive film.

Another aspect of the present invention is that the above-described anisotropically conductive adhesive film is disposed between a first electronic component having a plastic substrate and an electrode provided on the plastic substrate, and a second electronic component. and a step of thermocompression bonding the first electronic member and the second electronic member via an anisotropic conductive adhesive film to electrically connect the first electronic member and the second electronic member. , a method for manufacturing a connected structure.

According to the present invention, when connecting electronic components having plastic substrates, it is possible to obtain an anisotropic connection structure that has excellent adhesive strength, peel strength, and connection resistance after being placed in a high temperature and high humidity environment. A conductive adhesive film can be provided.

FIG. 1 is a schematic cross-sectional view showing one embodiment of an adhesive film. FIG. 2 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a connected structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiments.

FIG. 1 is a schematic cross-sectional view showing one embodiment of an anisotropic conductive adhesive film (hereinafter also simply referred to as "adhesive film"). As shown in FIG. 1, an adhesive film 1 according to one embodiment contains an adhesive component 2 and conductive particles 3 dispersed in the adhesive component 2. Adhesive component 2 is defined as solid content other than conductive particles 3.

The adhesive component 2 is a thermosetting component that hardens when heated. The adhesive component 2 may be, for example, a component that is cured by heating at 150°C or higher, or may be a component that is cured by heating at 250°C or lower. The adhesive component 2 contains one or more curable compounds. The curable compound has a reactive group that causes a curing reaction. The reactive group may be, for example, a known group that causes a radical polymerization reaction, an ionic polymerization reaction or a polyaddition reaction. The curable compound may have one reactive group, or may have two or more reactive groups. The curable compound may be a monomer, oligomer or polymer.

Examples of the reactive group that causes a radical polymerization reaction include a (meth)acroyl group. Examples of curable compounds having a (meth)acryloyl group include epoxy (meth)acrylate, (poly)urethane (meth)acrylate, methyl (meth)acrylate, polyether (meth)acrylate, polyester (meth)acrylate, and polybutadiene (meth)acrylate. ) acrylate, silicone acrylate, ethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate , n-hexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, isopropyl (meth)acrylate, hydroxypropyl (meth)acrylate, isobutyl (meth)acrylate, isobornyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, n-lauryl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-(meth)acryloyloxyethylphos Phate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, ) acrylate, polyethylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, cyclohexyl(meth)acrylate, dicyclopentenyl(meth)acrylate, dicyclopentenyloxyethyl(meth)acrylate, neopentyl glycol di( meth)acrylate, pentaerythritol (meth)acrylate, dipentaerythritol hexa(meth)acrylate, isocyanuric acid-modified bifunctional (meth)acrylate, isocyanuric acid-modified trifunctional (meth)acrylate, tricyclodecanyl acrylate, tricyclodecanedi Methanol diacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxypolyethoxy)phenyl] Examples include propane, 2,2-di(meth)acryloyloxydiethyl phosphate, and 2-(meth)acryloyloxyethyl acid phosphate.

A curable compound having a (meth)acryloyl group is a compound in which a (meth)acryloyl group is introduced into the terminal or side chain of a thermoplastic resin such as an acrylic resin, a phenoxy resin, or a polyurethane resin (for example, polyurethane (meth)acrylate). There may be. In this case, the weight average molecular weight of the curable compound may be, for example, 3,000 or more, 5,000 or more, 10,000 or more, 1,000,000 or less, and 500,000 or less. Generally, it may be 250,000 or less. The weight average molecular weight is measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve according to the following conditions.
(Measurement condition)
Equipment: GPC-8020 manufactured by Tosoh Corporation
Detector: Tosoh Corporation RI-8020
Column: Gelpack GLA160S+GLA150S manufactured by Hitachi Chemical Co., Ltd.
Sample concentration: 120mg/3mL
Solvent: Tetrahydrofuran Injection volume: 60μL
Pressure: 2.94×10 ⁶ Pa (30 kgf/cm ² )
Flow rate: 1.00mL/min

Examples of reactive groups that cause ionic polymerization reactions or polyaddition reactions include epoxy groups. Curable compounds having epoxy groups include bisphenol-type epoxy resins, which are the reaction products of epichlorohydrin and bisphenols A, F, AD, etc., and epoxy novolaks, which are the reaction products of epichlorohydrin, and phenol novolacs, cresol novolaks, etc. Examples include resins, naphthalene-based epoxy resins having a skeleton containing a naphthalene ring, and epoxy compounds having two or more glycidyl groups in one molecule such as glycidyl amine and glycidyl ether.

The content of the curable compound may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and 60% by mass or less, 55% by mass or less, or 50% by mass, based on the total mass of adhesive component 2. % or less.

When the curable compound contains a reactive group that causes a radical polymerization reaction, the adhesive component 2 further contains, for example, a thermal radical polymerization initiator. A thermal radical polymerization initiator is decomposed by heat to generate free radicals. Examples of thermal radical polymerization initiators include organic peroxides and azo compounds.

Specific examples of organic peroxides include 1,1,3,3-tetramethylbutylperoxyneodecanoate, di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxy Dicarbonate, cumyl peroxy neodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, t-butyl peroxy neodecanoate , t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy) Hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyneoheptanoate, t-amylperoxy-2-ethylhexanoate , di-t-butylperoxyhexahydroterephthalate, t-amylperoxy-3,5,5-trimethylhexanoate, 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, t-amylperoxy Oxyneodecanoate, t-amylperoxy-2-ethylhexanoate, di(3-methylbenzoyl) peroxide, dibenzoyl peroxide, di(4-methylbenzoyl) peroxide, t-hexylperoxyisopropyl Monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di(3- Methylbenzoylperoxy)hexane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzoate , dibutylperoxytrimethyladipate, t-amylperoxynormal octoate, t-amylperoxyisononanoate, t-amylperoxybenzoate and the like.

Specific examples of azo compounds include 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobisisobutyro Nitrile, 2,2'-azobis(2-methylbutyronitrile), 4,4'-azobis(4-cyanovaleric acid), 1,1'-azobis(1-cyclohexanecarbonitrile) and the like.

The content of the thermal radical polymerization initiator may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, and 15% by mass or less, 10% by mass, based on the total mass of adhesive component 2. % or less, or 5% by mass or less.

When the curable compound contains a reactive group that causes a radical polymerization reaction, the adhesive component 2 may further contain, for example, a polymerization inhibitor. The polymerization inhibitor may be hydroquinone, methyl ether hydroquinone, or the like. The content of the polymerization inhibitor may be 0.05% by mass or more and 5% by mass or less based on the total mass of adhesive component 2.

When the curable compound contains a reactive group that causes an ionic polymerization reaction or a polyaddition reaction, the adhesive component 2 is, for example, a polymerization initiator (also called a curing agent) that reacts with the reactive group to polymerize the curable compound. ). Examples of the polymerization initiator include melamine or its derivatives, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, diaminomaleonitrile, polyamine or its salt, dicyandiamide, polymercaptan, polyphenol, acid anhydride, and the like. The content of the polymerization initiator may be 1% by mass or more and 15% by mass or less based on the total mass of adhesive component 2.

Adhesive component 2 may further contain a thermoplastic resin. Examples of the thermoplastic resin include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, and phenol resin. The content of the thermoplastic resin may be 30% by mass or more, 40% by mass or more, or 50% by mass or more, and 80% by mass or less, 75% by mass or less, or 70% by mass, based on the total mass of adhesive component 2. % or less.

Adhesive component 2 may further contain a coupling agent. Examples of the coupling agent include silane coupling agents having organic functional groups such as (meth)acryloyl groups, mercapto groups, amino groups, imidazole groups, and epoxy groups. The content of the coupling agent may be 1% by mass or more and 10% by mass or less based on the total mass of adhesive component 2.

The adhesive component 2 may further contain fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, and the like.

The content of the adhesive component 2 may be 50% by volume or more and 98% by volume or less based on the total volume of the adhesive film 1.

The conductive particles 3 include, for example, polymer particles such as polystyrene and a metal layer covering the polymer particles. Although substantially the entire surface of the polymer particle is preferably coated with a metal layer, a portion of the surface of the polymer particle may be exposed without being coated with a metal layer.

The polymer constituting the polymer particles may be, for example, a polymer containing as a monomer unit at least one monomer selected from styrene and divinylbenzene. The diameter of the polymer particles may be, for example, 1 μm or more, or 2 μm or more, and 40 μm or less, 30 μm or less, or 20 μm or less.

The metal layer may be formed of a metal such as Ni, Ni/Au, Ni/Pd, Cu, NiB, Ag, or Ru. The metal layer may be a thin film produced by plating, vapor deposition, sputtering, or the like.

From the viewpoint of improving insulation, the conductive particles 3 may further include an insulating layer provided outside the metal layer and covering the metal layer. The insulating layer may be a layer formed from an insulating material such as silica or acrylic.

The conductive particles 3 may have a plurality of protrusions on their surfaces. Conductive particles having protrusions can be obtained, for example, by forming a metal layer on the surface of polymer particles by metal plating.

The average particle size of the conductive particles 3 may be 1 μm or more or 2 μm or more, and may be 40 μm or less, 30 μm or less, or 20 μm or less. In this specification, the particle size of 300 arbitrary conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle sizes is defined as the average particle size.

The content of the conductive particles is determined depending on the fineness of the electrodes to be connected, and may be 2% by volume or more and 50% by volume or less based on the total volume of the adhesive film 1.

The adhesive film 1 described above has a specific storage modulus after being cured. Specifically, the cured product obtained by thermally curing the adhesive film 1 at 200°C for 1 hour has a storage modulus of 0.7 GPa to 1.5 GPa at 40°C. By having such a storage modulus, it is possible to obtain a connection structure with excellent adhesive strength, peel strength, and connection resistance after being placed in a high temperature and high humidity environment when connecting electronic components having plastic substrates. It becomes possible. From the viewpoint of more preferably obtaining the above effects, the lower limit of the storage elastic modulus is preferably 0.8 GPa or more, more preferably 0.9 GPa or more, and still more preferably 1.0 GPa or more. From the viewpoint of more preferably obtaining the above effects, the upper limit value of the storage modulus is preferably 1.4 GPa or less, more preferably 1.3 GPa or less, still more preferably 1.2 GPa or less.

Note that the heat curing conditions of 200° C. for 1 hour are equivalent to the heat curing conditions of the adhesive film 1 when actually manufacturing a connected structure using the adhesive film 1, so the heat curing conditions were as follows: The storage elastic modulus of the cured product of the adhesive film 1 can be understood as reflecting the physical properties of the cured product of the adhesive film 1 in manufacturing the connected structure.

The storage modulus is measured by the following method.
First, the adhesive film 1 is placed in a heating furnace at 200° C. and heated for 1 hour to cure the adhesive film 1 and obtain a cured product. The cured product is cut into a strip of 2.0 mm x 20.0 mm and used as a measurement sample. In addition, when the short side of the adhesive film 1 is less than 2.0 mm, a measurement sample is cut out into a strip having the length of the short side x 20.0 mm. The measurement sample was measured at 40℃ using a dynamic viscoelasticity measuring device (for example, device name: RSA III, manufactured by TA Instruments) at a frequency of 10Hz and a heating rate of 10℃/min. Measure storage modulus.

The storage modulus of the adhesive film 1 can be adjusted by the composition of the adhesive component 2. Specifically, for example, when the number of reactive groups in one molecule of the curable compound is increased, the crosslink density after curing increases, and the storage modulus tends to increase. Furthermore, when the molecular structure of the curable compound is rigid (for example, it has a naphthalene skeleton), the storage modulus tends to increase. Alternatively, when a phenoxy resin or a polyester urethane resin having a high glass transition temperature is used as the thermoplastic resin, the storage modulus tends to increase.

The adhesive film 1 is suitably used for connecting electronic components. Hereinafter, a method for manufacturing a connected structure using adhesive film 1 will be explained. FIG. 2 is a schematic cross-sectional view showing one embodiment of a method for manufacturing a connected structure. In this manufacturing method, first, as shown in FIG. 2(a), a first electronic member 6 having a first substrate 4 and an electrode (first electrode) 5 provided on the first substrate 4; , a second substrate 7 and a second electronic member 9 having a second electrode 8 provided on the second substrate 7 are prepared.

Next, the first electronic member 6 and the second electronic member 9 are arranged so that the first electrode 5 and the second electrode 8 face each other, and the first electronic member 6 and the second electronic member An adhesive film 1 is placed between the member 9 and the member 9.

Then, the adhesive film 1 is cured by heating while pressurizing the entire film in the directions of arrows A and B. The pressure during pressurization may be, for example, 1 MPa or more and 10 MPa or less per total connected area. The heating temperature may be, for example, 150°C or higher and 250°C or lower. The time for applying pressure and heating may be, for example, 1 second or more and 160 seconds or less. In this way, the first electronic component 6 and the second electronic component 9 are thermocompression bonded via the adhesive film 1 (cured product of the adhesive film 1).

The connected structure 11 obtained in this way is a first electronic member having a first substrate 4 and a first electrode 5 provided on the first substrate 4, as shown in FIG. 2(b). 6, a second electronic member 9 having a second substrate 7 and a second electrode 8 provided on the second substrate 7, and between the first electronic member 6 and the second electronic member 9. A connecting member 10 is provided to electrically connect the first electrode 5 and the second electrode 8 to each other. The connecting member 10 is composed of a cured product of the adhesive film 1, and includes a cured product 12 of the adhesive component 2 and conductive particles 3 dispersed in the cured product 12. In the connection structure 11, the conductive particles 3 are interposed between the first electrode 5 and the second electrode 8, so that the first electronic member 6 and the second electronic member 9 are electrically connected to each other. It is connected.

The first substrate 4 is a plastic substrate and has flexibility. The second substrate 7 may be a polymer substrate, a glass substrate, a ceramic substrate, or the like.

The elastic modulus of the first substrate 4 (plastic substrate) is determined, for example, in consideration of the flexibility required for the connection structure 11 and the connection strength with the second electronic member 9. The elastic modulus of the first substrate 4 (plastic substrate) may be, for example, 2000 MPa or more and 4100 MPa or less.

The plastic substrate may be made of, for example, at least one thermoplastic resin selected from polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene naphthalate (PEN). The first substrate 4 may be formed of, for example, two or more plastic layers, and specifically includes, for example, a first plastic layer such as PET and a second plastic layer such as PI. You can leave it there. In this case, the second plastic layer has better heat resistance than the first plastic layer, and the first electrode 5 is provided on the second plastic layer.

The electrode materials forming the first electrode 5 and the second electrode 8 include Ag paste, metals such as Ni, Al, Au, Cu, Ti, and Mo, and metals such as ITO, IZO, silver nanowires, and carbon nanotubes. Examples include transparent conductors.

The first electronic component 6 may have an adhesive layer for bonding two or more components together. However, the elastic modulus of the adhesive layer is generally 0.1 MPa to 1.0 MPa, making it the softest of the materials constituting the first electronic component 6. Therefore, the influence of bending of the plastic substrate appears on the adhesive layer. Cheap. Therefore, since the deformation of the adhesive layer can affect the deformation of the entire first electronic component 6, it is preferable to select the adhesive layer in consideration of this point.

As a specific example of the connection structure 11 described above, a flexible organic electroluminescent color display (organic EL display). Further, as another specific example, it may be a so-called touch panel that combines a display element such as an organic EL display and a position input device such as a touch pad. The connection structure 11 may be, for example, a smart phone, a tablet, a television, a vehicle navigation system, a wearable terminal, or the like.

In the first electronic member 6 in the above specific example, a pixel drive circuit such as an organic TFT and a plurality of organic EL elements R, G are mounted on a plastic substrate (first substrate 4) such as PET or PEN. , B are arranged regularly in a matrix to form a display area. In this display area, signal lines and scanning lines for displaying video are formed in directions perpendicular to each other. In an organic EL display, for example, a set of organic EL elements R, G, and B, each of which emits red, green, and blue light, constitutes one pixel. The organic layer on which the organic EL element is formed is covered with a protective layer and sealed with a sealing substrate via an adhesive layer.

In the first electronic member 6, electrodes of a signal line and a scanning line for video display are drawn out to the outside of the display area, and each electrode is connected to a drive circuit element that is a driver for video display. Each electrode (first electrode 5) of the signal line and scanning line connected to the drive circuit element is arranged in accordance with the arrangement of bumps provided on the drive circuit element. Note that by using a light-transmissive substrate as the plastic substrate (first substrate 4), light from the organic EL element can be extracted from the back side of the substrate.

The second electronic member 9 in the above specific example may be a semiconductor electronic member, specifically, for example, an IC chip or an optical element such as an LED. The second electrode 8 in such a second electronic member 9 may be a bump electrode such as a gold stud bump or a solder bump.

Examples of the present invention will be described below, but the present invention is not limited to these Examples.

<Preparation of anisotropically conductive adhesive film>
After preparing an adhesive component with the formulation shown in Tables 1 and 2 below, conductive particles (average particle size: 3 μm) comprising polymer particles and a Ni plating layer covering the polymer particles are dispersed in the adhesive component. , a mixture of adhesive component and conductive particles was obtained. At this time, conductive particles were used in an amount such that the particle density of the conductive particles was 30,000 particles/mm ² . The obtained mixture was applied onto a PET film that had been subjected to a peeling process so that the thickness after drying was 20 μm, thereby producing anisotropically conductive adhesive films of each example and comparative example.

<Measurement of storage modulus>
Each of the obtained anisotropically conductive adhesive films was placed in a 200° C. heating furnace and heated for 1 hour to be cured. The cured product of the anisotropically conductive adhesive film was peeled off from the PET film and cut into a strip of 2.0 mm x 20.0 mm, which was used as a measurement sample. The storage elasticity of the measurement sample at 40°C was measured using a dynamic viscoelasticity measurement device (device name: RSA III, manufactured by TA Instruments) at a frequency of 10Hz and a heating rate of 10°C/min. The rate was measured. The results are shown in Tables 1 and 2.

<Evaluation>
- Evaluation of connection resistance (continuity resistance) -
Using each of the produced anisotropic conductive adhesive films, an IC chip with gold bumps (0.9 mm x 20.3 mm, thickness: 0.3 mm) and a plastic substrate with Ti/Al/Ti circuit (thickness: 0.05 mm) were fabricated. ) was connected as follows. Note that the area of the gold bump was 12 μm×100 μm. The space (pitch) between gold bumps was 12 μm. The height of the gold bump was 15 μm.

Subsequently, the anisotropically conductive adhesive film was cut out to a width of 2.0 mm and attached to the Ti/Al/Ti plastic substrate so that the anisotropically conductive adhesive film was in contact with the Ti/Al/Ti circuit-attached plastic substrate. . After placing the IC chip with gold bumps on the anisotropic conductive adhesive film, using a heat tool of 10 mm x 50 mm, using Teflon (registered trademark) with a thickness of 50 μm as a cushioning material, under the conditions of 170 ° C. and 60 MPa, A connected structure was obtained by heating and pressurizing for 5 seconds.

The connection resistance (continuity resistance) of the produced connected structure after being stored for 500 hours at a temperature of 85° C. and a humidity of 85% RH was measured by a four-terminal method. Using a constant current power supply R-6145 manufactured by Advantest Co., Ltd., a constant current (1 mA) was applied between the IC chip electrode and the polyimide substrate electrode (connection portion) of the connected structure sample. The potential difference between the connected parts when a current was applied was measured using a digital multimeter (R-6557) manufactured by Advantest Corporation. The potential difference was measured at 14 arbitrary points, and the average value was determined. The average value of the potential difference was converted into a connection resistance value. The obtained connection resistance values were evaluated based on the following criteria. The results are shown in Tables 1 and 2.
A: Connection resistance value is less than 5Ω B: Connection resistance value is 5Ω or more

-Evaluation of adhesive strength-
As the electronic components for evaluation, an IC chip with gold bumps (1.7 mm x 17 mm, thickness: 0.5 mm) and a plastic base material (thickness: 0.05 mm) were used.
The anisotropically conductive adhesive film was cut out to a width of 2.5 mm and was attached to a plastic substrate so that the anisotropically conductive adhesive film was in contact with the plastic substrate. After placing an IC chip with gold bumps on the anisotropic conductive adhesive film, it was heated at 170°C and 60 MPa using a heat tool measuring 10 mm x 50 mm and using Teflon (registered trademark) with a thickness of 50 μm as a cushioning material. A connected structure was obtained by heating and pressurizing for seconds.

The initial adhesive strength of the produced connected structure was measured by extruding an IC chip with gold bumps at a measurement speed of 16 μm/sec using an adhesive strength tester (4000 Puls manufactured by Nordson). The obtained adhesive strength was evaluated based on the following criteria. The results are shown in Tables 1 and 2.
A: Adhesive strength is 10 MPa or more B: Adhesive strength is less than 10 MPa

-Evaluation of peel strength-
As the electronic components for evaluation, an IC chip with gold bumps (1.7 mm x 17 mm, thickness: 0.5 mm) and a plastic substrate (thickness: 0.05 mm) were used.
The anisotropically conductive adhesive film was cut out to a width of 2.5 mm and was attached to a plastic substrate so that the anisotropically conductive adhesive film was in contact with the plastic substrate. After placing an IC chip with gold bumps on the anisotropic conductive adhesive film, it was heated at 170°C and 60 MPa using a heat tool measuring 10 mm x 50 mm and using Teflon (registered trademark) with a thickness of 50 μm as a cushioning material. A connected structure was obtained by heating and pressurizing for seconds.
The initial peel strength of the produced connected structure was measured using a tensile tester (STA-1150, manufactured by Orientec Co., Ltd.) by pulling up the plastic substrate at a measurement speed of 50 mm/min. The obtained peel strength was evaluated based on the following criteria. The results are shown in Tables 1 and 2.
A: Peel strength is 100 N/m or more B: Peel strength is less than 100 N/m

Each component in Tables 1 and 2 is as follows. The blending amounts of FX293, PKHC, FX316, UR-4800, UR-8200, UR-4125, UR-5537, and UA-5500-70T listed in Tables 1 and 2 are the blending amounts as solid content.

FX293: Biphenyl fluorene type phenoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., 40% by mass dissolved in a mixed solvent of ethyl acetate/toluene = 50/50 (mass ratio))
PKHC: Bisphenol A type phenoxy resin (manufactured by Tomoe Kogyo Co., Ltd., 40% by mass dissolved in a mixed solvent of ethyl acetate/toluene = 50/50 (mass ratio))
ZX1356-2: Copolymerized phenoxy resin of bisphenol A type and bisphenol F type (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., 45% by mass dissolved in a mixed solvent of ethyl acetate/toluene = 50/50 (mass ratio))
FX316: Bisphenol F type phenoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., 60% by mass dissolved in a mixed solvent of ethyl acetate/toluene = 50/50 (mass ratio))
HP-4032D: Naphthalene type epoxy resin (manufactured by DIC Corporation)
EXA-4850: Polyalkylene oxylated bisphenol A type epoxy resin (DIC Corporation)
SH-6040: Silane coupling agent (manufactured by Toray Dow Corning Co., Ltd.)
SI-60LA: Polymerization initiator (manufactured by Sanshin Chemical Industry Co., Ltd.)
UR-4800: Copolymerized polyester urethane resin (Toyobo Co., Ltd., 32% by mass dissolved in a mixed solvent of methyl ethyl ketone/toluene = 50/50 (mass ratio))
UR-8200: Copolymerized polyester polyurethane resin (Toyobo Co., Ltd., 30% by mass dissolved in a mixed solvent of methyl ethyl ketone/toluene = 50/50 (mass ratio))
UR-4125: Copolymerized polyester polyurethane resin (Toyobo Co., Ltd., 23% by mass dissolved in a mixed solvent of methyl ethyl ketone/toluene = 50/50 (mass ratio))
UR-5537: Copolymerized polyester polyurethane resin (Toyobo Co., Ltd., 30% by mass dissolved in a mixed solvent of methyl ethyl ketone/toluene = 50/50 (mass ratio))
UA-5500-70T: Urethane acrylate (Shin Nakamura Chemical Co., Ltd., 70% by mass dissolved in toluene)
DCPA: Tricyclodecane dimethanol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd.)
M215: Isocyanuric acid EO modified diacrylate (manufactured by Toagosei Co., Ltd.)
M315: Isocyanuric acid EO modified triacrylate (manufactured by Toagosei Co., Ltd.)
KBE502: 3-methacryloxypropylmethyldiethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
Niper BMT-K40: Polymerization initiator (manufactured by NOF Corporation)
LA7RT: Polymerization inhibitor (manufactured by Asahi Denka Kogyo Co., Ltd.)

From the results in Tables 1 and 2, the cured products obtained by thermally curing the anisotropically conductive adhesive films of Examples 1 to 8 at 200°C for 1 hour have a storage modulus of 0.7GPa to 1.5GPa at 40°C. In the case where the bonded structure had the following properties, a connected structure having excellent connection resistance, adhesive strength and peel strength after being placed in a high temperature and high humidity environment was obtained. On the other hand, Comparative Examples 1 and 2 and Comparative Examples 5 and 6, in which the storage modulus exceeds 1.5 GPa, were inferior in adhesive strength and peel strength. In addition, Comparative Examples 3, 4, 7, and 8, in which the storage modulus was less than 0.7 GPa, were inferior in connection resistance and adhesive strength after being placed in a high temperature and high humidity environment.

DESCRIPTION OF SYMBOLS 1... Adhesive film, 2... Adhesive component, 3... Conductive particles, 4... First substrate (plastic substrate), 5... Electrode (first electrode), 6... First electronic member, 7... Second Substrate, 8... Second electrode, 9... Second electronic member, 10... Connection member (cured adhesive film), 11... Connection structure.

Claims (3)

An anisotropic conductive adhesive film containing a thermosetting adhesive component and conductive particles,
An anisotropically conductive adhesive film (however, the cured product obtained by thermally curing the anisotropically conductive adhesive film at 200°C for 1 hour has a storage modulus of 0.7 GPa to 1.5 GPa at 40°C ) (excluding anisotropic conductive adhesive films containing an epoxy resin, an epoxy resin curing agent, and silicone fine particles with an average particle size of 300 nm or less) . a first electronic member having a plastic substrate and an electrode provided on the plastic substrate;
a second electronic member;
a connecting member that electrically connects the first electronic member and the second electronic member to each other;
A connected structure, wherein the connecting member is a cured product of the anisotropically conductive adhesive film according to claim 1. The anisotropic conductive adhesive film according to claim 1 is disposed between a first electronic member having a plastic substrate and an electrode provided on the plastic substrate, and a second electronic member, and a step of thermocompression bonding the first electronic member and the second electronic member via a conductive adhesive film to electrically connect the first electronic member and the second electronic member; A method for manufacturing a connected structure.

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