JP3947532B2 - Anisotropic conductive adhesive film - Google Patents

Description

The present invention relates to an anisotropic conductive adhesive film.

  In recent years, the necessity for fine circuit connection such as connection between a liquid crystal display (LCD) and a tape carrier package (TCP) and connection between a TCP and a printed circuit board (PCB) has increased. For the connection, a method using an anisotropic conductive adhesive film (ACF) in which conductive particles are dispersed in an adhesive resin is used.

  In this method, a film-like anisotropic conductive adhesive is sandwiched between members to be connected, and heated and pressed to maintain electrical insulation between adjacent terminals in the plane direction, while electrically conducting between upper and lower terminals. Is.

  As an adhesive resin in the anisotropic conductive adhesive, a thermosetting adhesive resin is used from the viewpoint of obtaining high connection reliability. As a thermosetting type adhesive resin, an epoxy resin system is used in order to improve adhesion to an adherend and moisture resistance reliability.

Moreover, as the curing agent for the epoxy resin, a material containing a latent material is used from the viewpoint of achieving both curability and storage stability. Examples of such latent curing agents include BF ₃ amine complex, dicyandiamide, organic acid hydrazide, and microcapsule type imidazole compound.

  The thermosetting type in which these latent curing agents are blended is usually one that is required to be heated and cured at a temperature of 170 ° C. to 200 ° C. for about 10 to 30 seconds (Patent Documents 1 and 2). ).

  Recently, however, LCD modules have become larger, more accurate, and have a narrower frame. Accordingly, connection pitches and connections have been narrowed rapidly. Therefore, for example, in the connection between the LCD and the TCP, the connection portion is displaced due to the elongation of the TCP due to heating at the time of connection, or because the connection portion is thin, the members inside the LCD are thermally at the temperature at the time of connection. I was affected. In connection between TCP and PCB, since the PCB is long, the PCB and LCD are warped by heating during connection, and the TCP wiring may be disconnected.

In order to solve these problems, there has been a demand for an anisotropic conductive adhesive that can be connected at a low temperature in a short time while maintaining sufficient connection reliability.
Japanese Patent Laid-Open No. 5-21094 JP 2002-327162 A

  However, epoxy resin thermosetting anisotropic conductive adhesives have low storage stability if they can be cured at low temperatures in a short time and at a level that can meet market demands even when latent curing agents are applied. On the contrary, those having excellent storage stability required a long time or high temperature for curing. All of these have advantages and disadvantages, and a technique for satisfying the balance between low-temperature short-time curing and storage stability has been demanded.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an anisotropic conductive adhesive excellent in storage stability and low-temperature short-time connectivity.

  This inventor repeated earnest examination aiming at making the storage stability and low-temperature short-time curability of an anisotropic conductive adhesive compatible. As a result, the inventors have found a condition that achieves both low-temperature short-time curability and storage stability, and have completed the present invention.

  In the past, although independent evaluation methods for low-temperature short-time curability and storage stability of anisotropic conductive adhesives were studied individually, the cause of the incompatibility of these was investigated and the product design was conducted. It was not just the idea of reflecting on On the other hand, in the present invention, the anisotropic conductive adhesive having excellent characteristics can be stably obtained by incorporating both low-temperature short-time curability and storage stability into the design of the anisotropic conductive adhesive. It became possible to get.

According to the present invention,
(A) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and (c) conductive particles as essential components,
Before film formation, and characterized in that it comprises the (a) mixture 2 days or more heated the at a temperature of 35 ° C. or higher 60 ° C. or less as the epoxy resins (b) microencapsulated imidazole derivative epoxy compound An anisotropic conductive adhesive film is provided.
In the anisotropic conductive adhesive film of the present invention, the resin flow coefficient may be 1.5 or more and 3.0 or less.
In the anisotropic conductive adhesive film of the present invention, the reaction rate may be 70% or more when pressure-bonded under a pressure of 3 MPa and heated and pressurized under a pressure of 3 MPa for 10 seconds.
In the anisotropic conductive adhesive film of the present invention, the tack after leaving at 40 ° C. for 3 days may be 70% or more of the tack before leaving.
In the anisotropic conductive adhesive film of the present invention, the resin flow coefficient after standing at 40 ° C. for 3 days may be 70% or more of the resin flow coefficient before standing.
In the anisotropic conductive adhesive film of the present invention, the viscosity after leaving the mixture of the (b) microencapsulated imidazole derivative epoxy compound and toluene at 40 ° C. for 90 minutes is 3 of the viscosity before standing. It may be less than double.

  By the way, it is difficult to obtain the anisotropic conductive adhesive film having predetermined storage stability and low-temperature short-time curability found in the present invention by a conventional production method. In the present invention, for the production of a film-like anisotropic conductive adhesive, a raw material having a predetermined configuration is selected and used, and pretreatment is performed under predetermined conditions, so that storage stability and low temperature for a short time can be obtained. It has been found that an anisotropic conductive adhesive film with excellent curability can be produced.

In the present invention,
(A) epoxy resin,
(B) microencapsulated imidazole derivative epoxy compounds, and include (c) conductive particles as an essential component, wherein prior to film formation (a) heated above as mixtures with epoxy resins (b) microencapsulated imidazole Including derivative epoxy compounds.

Since the anisotropic conductive adhesive film according to the present invention, the prior film formation (a) heated above as mixtures with epoxy resins (b) microencapsulated imidazole derivative epoxy compound is used, the storage stability And low temperature short time curability can be improved reliably.

In the present invention, prior to the film formation, the (a) mixture is heated 35 ° C. or higher 60 ° C. over 2 days under the following temperature conditions as the above (b) microencapsulated imidazole derivative epoxy and epoxy resins Contains compounds. (B) By heating the microencapsulated imidazole derivative epoxy compound for a relatively long period of time, the storage stability and the low temperature short time curability can be more reliably improved.

In the present invention, the average particle size of the (b) microencapsulated imidazole derivative epoxy compound may be 0.1 μm or more and 3 μm or less. (B) The storage stability can be further improved by setting the average particle diameter (d ₅₀ ) of the microencapsulated imidazole derivative epoxy compound to 0.1 μm or more. Moreover, by setting the average particle size to 3 μm or less, the epoxy resin can be reliably cured under low-temperature and short-time heating conditions. For this reason, it can be set as the structure which was further excellent in low-temperature short-time curability and storage stability.

  In the present invention, the thickness of the microcapsule wall material film of the (b) microencapsulated imidazole derivative epoxy compound may be 0.001 μm or more and 0.3 μm or less. By making the thickness of the microcapsule wall material film 0.001 μm or more, the storage stability can be further improved. In addition, by setting the thickness of the microcapsule wall material film to 0.3 μm or less, the anisotropic conductive adhesive can be surely cured even when heating at a low temperature for a short time. For this reason, it can be set as the structure which was further excellent with low-temperature short-time curability and storage stability.

  In addition, as the (b) microencapsulated imidazole derivative epoxy compound, the above-described microcapsules having a thin film thickness are particularly selected and used, and further preheated under predetermined conditions. By carrying out like this, the storage stability and low temperature short time curability of an anisotropic conductive adhesive can further be improved.

  In the present invention, (d) an elastomer having a nitrile group and an epoxy group may be further included. By carrying out like this, the adhesiveness with respect to a polyimide can be improved. Since polyimide is used as a material such as a COF (chip on film) base material, (d) a structure containing an elastomer having a nitrile group and an epoxy group provides adhesion to a base material such as COF. Can be improved.

  In the present invention, the epoxy resin may include an epoxy resin having a naphthalene skeleton. By carrying out like this, the fluidity | liquidity of an adhesive agent can be reduced and a quick curability can further be improved.

  Although the present invention has been described above, any combination of these components, and those in which the components and expressions of the present invention are mutually replaced between methods and apparatuses are also effective as an aspect of the present invention.

  For example, according to the present invention, there is provided an electronic device characterized in that an electronic component or an electrical component is electrically joined through the anisotropic conductive adhesive.

  In the present invention, the electronic component or the electric component is a semiconductor element, a semiconductor device, a printed circuit board, a liquid crystal display (LCD), a panel, a plasma display (PDP) panel, an electroluminescence (EL) panel, or a field emission display ( FED) panel.

As described above, according to the present invention, (a) an epoxy resin, (b) a microencapsulated imidazole derivative epoxy compound, and (c) conductive particles are included as essential components. It was heated over 2 days at a temperature mixture as a 35 ° C. or higher 60 ° C. or less of the epoxy resins with the configuration including the (b) microencapsulated imidazole derivative epoxy compound, the storage stability and low temperature for a short time An anisotropic conductive adhesive film excellent in connectivity is realized.

Hereinafter, the anisotropic conductive adhesive according to the present invention will be described.
The anisotropic conductive adhesive of the present invention is
(A) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and (c) an electrically conductive particle as an essential component, and an insulating adhesive containing (a) and (b) and (c) an electrically conductive particle. The anisotropic conductive adhesive of the present invention is in the form of a film.

  (B) The microencapsulated imidazole derivative epoxy compound is a latent curing agent and an essential component of the insulating adhesive. Specifically, particles such as NOVACURE manufactured by Asahi Kasei Corporation can be used.

  The average particle size of the particles of the microencapsulated imidazole derivative epoxy compound can be, for example, 0.1 μm or more, preferably 1 μm or more. By doing so, storage stability can be improved. Moreover, it can be set as the structure which suppresses a viscosity raise and can produce stably the microencapsulated imidazole derivative epoxy compound.

  The average particle diameter of the microencapsulated imidazole derivative epoxy compound particles is, for example, 3 μm or less, and preferably 2 μm or less. By doing so, the curing reactivity is increased by increasing the reaction point between the latent curing agent and the resin, and connection at a low temperature and in a short time becomes possible. In addition, it is possible to secure a sufficient number of reaction points and reliably cure at a low temperature in a short time.

  In addition, the average particle diameter of the (b) microencapsulated imidazole derivative epoxy compound used in the present invention was an average particle diameter in terms of volume in a laser diffraction type measurement apparatus RODOS SR type (SYMPATEC HEROS & RODOS).

  The thickness of the capsule wall material film of the microencapsulated imidazole derivative epoxy compound can be 0.001 μm or more, preferably 0.01 μm or more. By doing so, it is possible to secure a sufficient strength of the wall material film and to produce a wall material film having no defect. For this reason, it can suppress that a wall material film | membrane is damaged by mechanical share and a solvent during mixing with another raw material, and storage stability falls.

  The thickness of the capsule wall material film of the microencapsulated imidazole derivative epoxy compound can be, for example, 0.3 μm or less, preferably 0.1 μm or less. By doing so, it is possible to sufficiently shorten the time until the wall material film breaks while ensuring the storage stability of the wall material film. For this reason, adhesion at a low temperature in a short time can be reliably performed.

  The thickness of the capsule wall material film of (b) the microencapsulated imidazole derivative epoxy compound can be determined, for example, by observation with a transmission electron microscope (TEM) of the cross section of the (b) microencapsulated imidazole derivative epoxy compound.

  The microencapsulated imidazole derivative epoxy compound is not particularly limited as long as the reaction product of the imidazole derivative and the epoxy compound is microencapsulated into a fine powder. A compound in which a microencapsulated imidazole derivative epoxy compound and an isocyanate compound are reacted to improve chemical resistance and storage stability is further preferable.

  Examples of the epoxy compound used for the microencapsulated imidazole derivative epoxy compound include glycidyl ether type epoxy resins such as bisphenol A, bisphenol F, and brominated bisphenol A, dimer acid diglycidyl ester, and phthalic acid diglycidyl ester.

  Examples of imidazole derivatives used herein include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl- 2-methylimidazole, 1-benzyl-2-ethylimidazole, 1-benzyl-2-ethyl-5-methylimidazole, 2-phenyl-4-methyl-5-hydroxydimethylimidazole, 2-phenyl-4,5-dihydroxy And methyl imidazole.

  The addition amount of the microencapsulated imidazole derivative epoxy compound is not particularly limited, but is preferably 5 parts by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the total of the elastomer and the epoxy resin. If the blending amount is too large, the heat resistance and moisture resistance when the anisotropic conductive adhesive is used are lowered, and there is a concern that the connection reliability is lowered. Moreover, when the compounding amount is too small, there is a concern that the curability is lowered.

  The microencapsulated imidazole derivative epoxy compound may be a blended product. For example, a blended product of a microencapsulated imidazole derivative epoxy compound and an epoxy resin may be used. In this case, the amount of the microencapsulated imidazole derivative epoxy compound added can be adjusted, for example, within the above range in consideration of the amount of the epoxy resin contained in the blend of the microencapsulated imidazole derivative epoxy compound.

  Next, (a) the epoxy resin is not particularly limited as long as it has at least two epoxy groups in one molecule. For example, a glycidyl ester type epoxy resin or a epoxy resin having a naphthalene skeleton can be used. By carrying out like this, hardening for a short time can be obtained reliably. Further, 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, or the like may be used. The epoxy resin is not limited to these, and may be used alone or in combination. From the viewpoint of moisture resistance reliability, it is preferable that Na ions and Cl ions, which are ionic impurities in the epoxy resin, be as small as possible. it can.

  The blending amount of (a) epoxy resin is preferably 50 parts by weight or more and 2000 parts by weight or less with respect to 100 parts by weight of (b) microencapsulated imidazole derivative epoxy compound. If the blending amount is too large, curability when an anisotropic conductive adhesive is obtained is lowered. On the other hand, if the blending amount is too small, the heat resistance and moisture resistance are lowered, and the connection reliability when an anisotropic conductive adhesive is obtained is lowered.

  Here, the naphthalene type epoxy resin having a naphthalene skeleton has a skeleton containing at least one naphthalene ring in one molecule, and includes a naphthol type and a naphthalene diol type. By using a naphthalene type epoxy resin, the glass transition temperature Tg of the cured product of the anisotropic conductive adhesive can be improved. Moreover, the linear expansion coefficient in the high temperature range of hardened | cured material can be reduced. The addition amount of the naphthalene-based epoxy resin can be, for example, 5% by weight or more and 80% by weight or less, preferably 10% by weight or more and 50% by weight or less with respect to the entire epoxy resin component in the anisotropic conductive adhesive. By doing so, film formability and curing reactivity can be improved.

  The anisotropic conductive adhesive according to the present invention may further contain an elastomer. By including an elastomer, film formation can be reliably performed. The elastomer can also be a reactive elastomer. By carrying out like this, an anisotropic conductive adhesive can be reliably made into a film and can be made into a sheet form. In addition, the elastic modulus of the cured resin can be lowered to improve the adhesive force, and the residual stress at the time of connection can be reduced. For this reason, connection reliability can be improved.

  The material of the elastomer is not particularly limited, but has a film-forming property, such as phenoxy resin, polyester resin, polyurethane resin, polyimide resin, polybutadiene, polypropylene, styrene-butadiene-styrene copolymer, polyacetal resin, Polyvinyl butyral resin, butyl rubber, chloroprene rubber, polyamide resin, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinyl acetate resin, nylon, styrene-isoprene copolymer A coalescence, a styrene-butylene-styrene block copolymer, etc. can be used, and it can use individually or in mixture of 2 or more types.

  Although the compounding quantity of an elastomer is not specifically limited, It is preferable that they are 10 parts or more and 300 parts or less with respect to a total of 100 parts of an epoxy resin and a microencapsulated imidazole derivative epoxy compound. If the blending amount is too large, the fluidity of the anisotropic conductive adhesive is lowered, so that the connection reliability is lowered. Moreover, wettability with various adherends decreases, and adhesion decreases. Moreover, when a compounding quantity is too small, the film formability at the time of setting it as an anisotropic conductive adhesive will fall. Moreover, since the elasticity modulus of hardened | cured material becomes high, there exists a possibility that the adhesiveness with respect to various to-be-adhered bodies may fall, or the connection reliability after a thermal shock test may fall.

  As the elastomer, a resin having a nitrile group and an epoxy group can be used. As such a resin, for example, acrylic rubber can be used. Examples of the acrylic rubber include a polymer or copolymer having at least one of acrylic acid, acrylic acid ester, methacrylic acid ester or acrylonitrile as a monomer component, including glycidyl acrylate or glycidyl methacrylate containing a glycidyl ether group. A copolymer acrylic rubber is preferably used.

  Specifically, the acrylic rubber can be, for example, a compound represented by the following general formula (1).

However, in the general formula (1), R ₁ represents any one of hydrogen, methyl group, ethyl group, propyl group, and butyl group, and R ₂ represents hydrogen, methyl group, ethyl group, propyl group, and butyl group. Indicates one of the following. R ₁ and R ₂ may be the same group or different groups. Moreover, in the said General formula (1), X is 40 mol% or more and 98.5 mol% or less, Y is 1 mol% or more and 50 mol% or less, Z is 0.5 mol% or more and 10 mol% or less. The molecular weight of the acrylic rubber represented by the general formula (1) is, for example, 10,000 or more and 1500,000 or less. By using the acrylic rubber represented by the general formula (1), the adhesion and connection reliability can be further improved.

  Next, in the present invention, the composition of (c) conductive particles is not limited. The particle size, material, and blending amount of the conductive particles can be appropriately selected according to the pitch and pattern of the circuit to be connected, the thickness and material of the circuit terminal, and the like. For example, metal particles or particles obtained by coating a polymer core material with metal can be used.

  As the metal particles, gold, silver, zinc, tin, solder, indium, palladium or the like may be used alone or in combination of two or more.

  In addition, as the particles obtained by metal coating the polymer core material, the epoxy resin, urethane resin, melamine resin, phenol resin, acrylic resin, polyester resin, polystyrene resin, styrene-butadiene copolymer, etc. You may combine 1 type (s) or 2 or more types from gold | metal | money, nickel, silver, copper, zinc, tin, indium, palladium, aluminum, etc. to the thing which combined 1 type (s) or 2 or more types from a polymer, and a metal thin film membrane | film | coat.

  Although there is no restriction | limiting in particular in the thickness of a metal thin film membrane | film | coat, For example, they can be 0.01 micrometer or more and 1 micrometer or less. If the metal thin film is too thin, the anisotropic conductive adhesive will cause unstable connection, and if it is too thick, agglomeration will occur. is there. The metal thin film is preferably uniformly coated on the surface of the polymer core material. By coating uniformly, unevenness and chipping of the film can be eliminated and electrical connectivity can be improved.

  The compounding quantity of electroconductive particle can be 0.1 volume% or more and 10 volume% or less with respect to the sum total of an elastomer, an epoxy resin, and a microencapsulated imidazole derivative epoxy compound, for example. If the blending amount is too large, the absolute amount of conductive particles in the anisotropic conductive adhesive increases, and the insulation between the adherend connection terminals decreases. On the other hand, if the blending amount is too small, the absolute amount of conductive particles in the anisotropic conductive adhesive decreases, so that the conductive particles on the adherend connection terminal are insufficient and the connection resistance value is increased.

  An appropriate amount of a coupling agent may be added to the anisotropic conductive adhesive of the present invention as necessary. By adding the coupling agent, it is possible to modify the adhesiveness of the adhesion interface of the anisotropic conductive adhesive. Moreover, the heat resistance and moisture resistance of the anisotropic conductive adhesive can be improved.

  Although it does not specifically limit as a coupling agent, A silane coupling agent can be used conveniently, for example, (gamma) -glycidoxy propyl triethoxysilane, (beta)-(3,4 epoxy cyclohexyl) ethyl trimethoxy. Examples include silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, γ-ureidopropyltriethoxysilane, and the like. You may mix above.

  Further, the anisotropic conductive adhesive according to the present invention has various additives such as a non-reactive diluent, a reactive diluent, a rocking agent for improving various properties such as resin compatibility, stability, and workability. Modification modifiers, thickeners, inorganic fillers and the like may be added as appropriate.

  Next, a method for producing the anisotropic conductive adhesive according to the present invention will be described. An anisotropic conductive adhesive is obtained by uniformly dispersing an insulating adhesive containing a latent curing agent, conductive particles, and other additives as required in a solvent such as toluene or ethyl acetate. Moreover, the anisotropic conductive adhesive film which concerns on this invention apply | coats the obtained dispersion liquid on a peeling base material (for example, polyester sheet) in a film form, removes a solvent below the active temperature of a hardening | curing agent, and dries. It is manufactured by.

  However, it is difficult to obtain the anisotropic conductive adhesive according to the present invention by the above-described conventional method. Therefore, in the present invention, as the (b) microencapsulated imidazole derivative epoxy compound, only those having a particle diameter and a shell layer thickness within a certain range are selected and used. Further, the selected (b) microencapsulated imidazole derivative epoxy compound is preheated as a pretreatment.

  The temperature of the preheating can be, for example, 35 ° C. or more and 60 ° C. or less. By setting it as 35 degreeC or more, the storage stability of an anisotropically conductive adhesive agent can be improved reliably. Moreover, the fall of short-time curability of an anisotropic conductive adhesive can be suppressed by setting it as 60 degrees C or less.

  The preheating time is preferably 2 days or longer. By carrying out like this, the preservability of a latent hardening agent can be improved certainly.

  Specifically, the preheating conditions may be, for example, 40 ° C. and 4 to 5 days. By performing preheating at a low temperature for a relatively long period of time, it is possible to stably obtain an anisotropic conductive adhesive that is superior in both low temperature short time effectiveness and storage stability as compared with the conventional configuration. . In addition, about the selection of the raw material at the time of producing the anisotropic conductive adhesive which concerns on this invention, and selection of preheating conditions, it shows in detail in the Example mentioned later.

  In the present invention, since the (b) microencapsulated imidazole derivative epoxy compound selected as the latent curing agent is preheated and used, the film-like anisotropic conductivity satisfying at least one of the following conditions: For the first time, it is possible to obtain an adhesive.

The anisotropic conductive adhesive film according to the present invention has a condition of either (A1) or (A2) and (B1) to (B3) as an index of low temperature short time curability (A) and storage stability (B). ) may be less than both the one of the conditions.
(A1) The resin flow coefficient is 1.5 or more and 3.0 or less,
(A2) The reaction rate is 70% or more when pressure-bonded under a heating and pressurizing condition in which the temperature is increased to 170 ° C. for 10 seconds at 3 MPa.
(B1) The tack after leaving at 40 ° C. for 3 days is 70% or less of the tack before leaving,
(B2) The resin flow coefficient after standing for 3 days at 40 ° C. is 70% or more of the resin flow coefficient before standing.
(B3) The viscosity of the mixture obtained by mixing the microencapsulated imidazole derivative epoxy compound and toluene at 40 ° C. for 90 minutes is not more than 3 times the viscosity before standing.

Specifically, the anisotropic conductive adhesive film according to the present invention may satisfy any of (A1), (A2) and (B1) to (B3), and more specifically, (A1) And (B1), (A1) and (B2), (A1) and (B3), (A2) and (B1), (A2) and (B2), or (A2) and (B3) it may meet.

  In the present invention, it is possible to achieve both low-temperature short-time curing and storage stability by combining the conditions for low-temperature short-time curability (A) and storage stability (B). Further, the anisotropic conductive adhesive satisfying both of them can be obtained only by preheating latent curing agent particles having a specific shape (particle diameter, film thickness) under specific conditions as described above. .

  In addition, in this specification, the resin flow coefficient is obtained when another glass substrate is disposed on the anisotropic conductive adhesive film affixed on the glass substrate and the temperature is increased to 170 ° C. at 7 MPa for 10 seconds. Is the area ratio before and after pressing. If the low temperature short time curability is good, the resin flow coefficient becomes small.

Further, the reaction rate is calculated as follows by measuring the attenuation amount of the epoxy ring by FT-IR measurement. The following three (i) to (iii) are used as measurement samples.
(I) Uncured anisotropic conductive adhesive film (raw film),
(Ii) a fully cured film obtained by curing a raw film in an oven at 180 ° C. for 1 hour,
(Iii) A film under a connecting condition of 170 ° C. × 10 seconds.

FTIR measurement of each sample is performed, and from the obtained IR chart,
(I) 914 cm ⁻¹ : inverse target stretching vibration of epoxy ring, and (II) 829 cm ⁻¹ : C-H interfacial variable angular vibration of aromatic ring,
Two peaks are digitized and for each sample,
Absorbance ratio = (I) / (II)
Ask for. And the reaction rate shown by a following formula is computed using the obtained absorbance ratio.
Reaction rate (%) = (1− (iii) absorbance ratio / (i) absorbance ratio) / (1− (ii) absorbance ratio / (i) absorbance ratio) × 100

  The tack can be obtained, for example, by measuring the surface tack force of the anisotropic conductive adhesive sheet at 30 ° C. using a tack tester having a probe having a diameter of 5 mm.

  (B) The viscosity of the microencapsulated imidazole derivative epoxy compound is measured by dispersing a mixture of the microencapsulated imidazole derivative epoxy compound and the epoxy resin in toluene and measuring the solution viscosity with a rotational viscometer.

  The anisotropic conductive adhesive film according to the present invention is excellent in low-temperature short-time curability and storage stability, and is suitably used for connecting electronic parts or electrical parts. Examples of the electronic component or electrical component include a semiconductor element, a semiconductor device, a printed circuit board, an LCD panel, a PDP panel, an EL panel, and an FED panel. More specifically, for example, in a liquid crystal display device, it is suitably used for electrical connection between fine circuits such as connection between an LCD panel and TCP, or connection between TCP and PCB.

  A display device which is one of electronic devices obtained using the anisotropic conductive adhesive film of the present invention will be described. Here, a case where the display device is an LCD (liquid crystal display) module will be described as an example. FIG. 1 is a cross-sectional view schematically showing an example of the LCD module of the present invention.

  The LCD module 10 includes an LCD panel 11 and a circuit board. The circuit board includes a TCP (tape carrier package) 12 and a PCB (printed circuit board) 13. The LCD panel 11 and the TCP 12 and the TCP 12 and the PCB 13 are bonded by a film-like anisotropic conductive adhesive 14.

  FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. As shown in FIG. 2, a TCP electrode 18 is provided as a circuit terminal on the surface of the TCP 12 facing the LCD panel 11. Further, an ITO (indium tin oxide) electrode 17 is provided as a circuit terminal on the surface of the LCD panel 11 facing the TCP 12. Although not shown in FIGS. 1 and 2, PCB electrodes are provided as circuit terminals on the surface of the PCB 13 facing the TCP 12.

  The anisotropic conductive adhesive 14 includes an adhesive resin 16 and conductive particles 15 dispersed in the adhesive resin 16. The ITO electrode 17 and the TCP electrode 18 or the TCP electrode 18 and the PCB electrode (not shown) are electrically connected via the anisotropic conductive adhesive 14. Since the anisotropic conductive adhesive 14 includes the conductive particles 15, electrical connection between the circuit terminals is ensured.

  Thus, the anisotropic conductive adhesive 14 can be suitably used as a connection member around the display device. Further, the anisotropic conductive adhesive 14 according to the present invention can be more suitably used as an output connection member for connecting the TCP 12 and the LCD panel 11.

  In FIG. 1, the LCD panel 11 is used as the display device substrate. However, the present invention is not limited to this, and can be applied to, for example, an electroluminescence panel, a plasma display panel, and the like.

  The present invention has been described based on the embodiments. It should be understood by those skilled in the art that these embodiments are illustrative and that various modifications are possible, and that such modifications are within the scope of the present invention.

  For example, the display member and the adherend can be joined via the anisotropic conductive adhesive of the present invention to obtain a display device according to the present invention.

  In addition, the circuit board and the adherend can be bonded via the anisotropic conductive adhesive of the present invention to provide an electronic apparatus according to the present invention.

  Hereinafter, although an example explains the present invention, the present invention is not limited to this.

(Experimental example 1)
100 parts by weight of bisphenol A type phenoxy resin (PKHC manufactured by Inchem Co., Ltd., weight average molecular weight Mw = 50000, ethyl acetate 20% by weight solution),
50 parts by weight of polyvinyl butyral resin (BX made by Sekisui Chemical Co., Ltd., polymerization degree 1700, butyralization degree 65 mol%, ethyl acetate 20% by weight solution)
20 parts by weight of bisphenol A type epoxy resin (Epicoat 828 manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent 180 g / eq),
30 parts by weight of a bisphenol F type epoxy resin (Epicoat 806 manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent of 175 g / eq),
20 parts by weight of microencapsulated 2-methylimidazole derivative epoxy compound (average particle size 3 μm, capsule membrane material thickness 0.2 μm), and Ni / Au plated acrylic particles (Micropearl AUL-705 manufactured by Sekisui Chemical Co., Ltd., average particle size) 5 μm) 3 parts by weight,
Were mixed and dispersed uniformly.

However, prior to mixing, a mixture in which a microencapsulated 2-methylimidazole derivative epoxy compound and an epoxy resin component used for blending were mixed at a blending ratio was placed in a 200 ml container, and preheating was performed. The preheating conditions are shown in the table. This was applied onto polyethylene terephthalate that had been subjected to a release treatment so that the thickness after drying was 15 μm, and dried. The dried product was cut into a width of 1.5 mm to obtain an anisotropic conductive adhesive film.

  The resin flow coefficient, reaction rate, tack change, resin flow coefficient change, adhesive strength, connection reliability, and storage stability of the obtained anisotropic conductive adhesive film were evaluated by the methods described later. The resin flow coefficient and reaction rate were used as indicators of short-term curability. Further, tack change and resin flow coefficient change were used as indices of storage stability. However, the tack change is the ratio (%) of the tack after being left at 40 ° C. for 3 days to the tack before being left, and the resin flow coefficient change is before leaving the resin flow coefficient after being left at 40 ° C. for 3 days. It is a ratio (%) to the resin flow coefficient.

  Moreover, the viscosity change in toluene of the microencapsulated 2-methylimidazole derivative epoxy compound used was evaluated and used as an index of storage stability. Here, the viscosity change is the viscosity after leaving a solution in which a mixture of a microencapsulated imidazole derivative epoxy compound and an epoxy resin component used for blending mixed in toluene at a blending ratio was allowed to stand at 40 ° C. for 90 minutes. It is the ratio to the viscosity before standing.

(Experimental Examples 2 and 3)
As shown in Table 1, an anisotropic conductive adhesive film was prepared in the same manner as in Experimental Example 1, except that the particle size and capsule membrane material thickness of the microencapsulated 2-methylimidazole derivative epoxy compound were changed from those in Experimental Example 1. Produced.

(Experimental Examples 4 and 5)
As shown in Table 1, the particle size and capsule membrane material thickness of the microencapsulated 2-methylimidazole derivative epoxy compound were changed from those of Experimental Example 1. The epoxy resin was blended in 15 parts by weight of bisphenol A type epoxy resin and 35 parts by weight of bisphenol F type epoxy resin. An anisotropic conductive adhesive film was produced in the same manner as in Experimental Example 1. In Experimental Example 5, 2 parts by weight of γ-glycidoxypropyltriethoxysilane was further blended as a coupling agent.

(Experimental Examples 6-9)
As shown in Tables 1 and 2, instead of the polyvinyl butyral resin used in Experimental Example 1 as an elastomer, an acrylonitrile-butadiene-methacrylic acid copolymer (20% by weight ethyl acetate solution) represented by the following formula (2) is used. Using.

(However, in said formula (2), it is 1:27 wt%, n: 4.0 mol%, molecular weight: 100,000.)

  Moreover, in Experimental Examples 6-8, the compounding of the epoxy resin was 30 parts by weight of bisphenol A type epoxy resin and 20 parts by weight of bisphenol F type epoxy resin. In Experimental Example 8, γ-glycidoxypropyltriethoxysilane was further blended as a coupling agent. In Experimental Example 9, the epoxy resin was blended with 20 parts by weight of a bisphenol A type epoxy resin and 30 parts by weight of a bisphenol F type epoxy resin, and γ-aminopropyltriethoxysilane was further blended as a coupling agent. Then, an anisotropic conductive adhesive film was produced in the same manner as in Experimental Example 1 by changing the particle size and capsule membrane material thickness of the microencapsulated 2-methylimidazole derivative epoxy compound.

(Experimental Examples 10-12)
As shown in Table 2, anisotropic conductivity was obtained using the bisphenol A type phenoxy resin, polyvinyl butyral resin and acrylonitrile-butadiene-methacrylic acid copolymer used in Experimental Example 6 as the elastomer used in Experimental Example 1. An adhesive film was prepared. In Experimental Example 12, γ-glycidoxypropyltriethoxysilane was used as a coupling agent.

(Experimental Examples 13 to 14)
As shown in Table 2, bisphenol A type phenoxy resin as an elastomer and an epoxy group-containing acrylic rubber represented by the above general formula (1) (ethyl acetate 20 wt% solution, R ₁ = C in the above general formula (1)) ₂ H ₅ , R ₂ = CH ₃ , molecular weight 700,000) to produce an anisotropic conductive adhesive film. In Experimental Example 13, γ-glycidoxypropyltriethoxysilane was used as a coupling agent.

(Experimental Examples 15 to 16)
As shown in Table 2, in addition to bisphenol A type epoxy resin and bisphenol F type epoxy resin as an epoxy resin, a naphthalene type epoxy resin (HP-4032 manufactured by Dainippon Ink Co., Ltd.) is used, and an anisotropic conductive adhesive film is used. Produced. In Experimental Example 16, γ-aminopropyltriethoxysilane was used as a coupling agent.

(Experimental Examples 17 to 21)
As shown in Table 3, in Example 1, anisotropic conductive adhesive films were obtained by changing the average particle size and capsule membrane material thickness of the microencapsulated imidazole derivative epoxy compound. In Experimental Examples 19 and 20, the compounding of the epoxy resin was different from that in Experimental Example 1. In Experimental Examples 17, 18, and 21, the pre-heating of the microencapsulated imidazole derivative epoxy compound was not performed. In Experimental Example 19, the preheating conditions for the microencapsulated imidazole derivative epoxy compound were 50 ° C. and 16 hours. In Experimental Example 20, the preheating conditions for the microencapsulated imidazole derivative epoxy compound were 50 ° C. and 8 hours.

(Experimental Examples 22-24)
As shown in Table 3, in Experimental Example 6, the microencapsulated imidazole derivative epoxy compound was a microencapsulated 2-phenyl-4-methylimidazole derivative epoxy compound. An anisotropic conductive adhesive film was obtained by changing the average particle size and capsule membrane thickness of this compound. In Experimental Examples 23 and 24, the compounding ratio of the epoxy resin was different from that in Experimental Example 6. In Experimental Example 23, the pre-heating of the microencapsulated imidazole derivative epoxy compound was not performed. In Experimental Example 22, the preheating conditions for the microencapsulated imidazole derivative epoxy compound were 50 ° C. and 8 hours. In Experimental Example 24, the preheating conditions for the microencapsulated imidazole derivative epoxy compound were 50 ° C. and 16 hours.

  Tables 1 to 3 show the blending amounts and evaluation results of the adhesives created in the above experimental examples. The evaluation items in Tables 1 to 3 were measured by the following methods, respectively.

Resin flow coefficient The produced anisotropic conductive adhesive film was stuck on a glass substrate. And another glass substrate was arrange | positioned on an anisotropic conductive adhesive film, and it heated up to 170 degreeC at 10 MPa for 10 second. And the area ratio before and behind heat-pressing was computed, and it was set as the resin flow coefficient.

Reaction Rate In the anisotropic conductive adhesive film according to each experimental example, the following three (i) to (iii) were used as measurement samples.
(I) an uncured anisotropic conductive adhesive sheet (raw film),
(Ii) a fully cured film obtained by curing a raw film in an oven at 180 ° C. for 1 hour,
(Iii) A film under a connecting condition of 170 ° C. × 10 seconds.

FTIR measurement of each sample was performed. From the obtained IR chart,
(I) 914 cm ⁻¹ : inverse target stretching vibration of epoxy ring, and (II) 829 cm ⁻¹ : C-H interfacial variable angular vibration of aromatic ring,
Two peaks are digitized and for each sample,
Absorbance ratio = (I) / (II)
And the reaction rate represented by the following formula was calculated using the obtained absorbance ratio.
Reaction rate (%) = (1− (iii) absorbance ratio / (i) absorbance ratio) / (1− (ii) absorbance ratio / (i) absorbance ratio) × 100

Tack The surface tack force of the anisotropic conductive adhesive sheet at 30 ° C. was measured using a tack tester having a probe with a diameter of 5 mm.

Viscosity change in toluene of microencapsulated imidazole derivative epoxy compound Solution in which 4 parts by weight of a mixture in which microencapsulated imidazole derivative epoxy compound and used epoxy resin component were blended at a blending ratio shown in the table were dispersed in 1 part by weight of toluene. Was measured with a rotational viscometer (E-type viscometer, 50 rpm) at 25 ° C., and the ratio of the viscosity after standing at 40 ° C. for 90 minutes with respect to the initial viscosity was calculated.

Preparation of samples for measuring adhesive strength, connection reliability, and storage stability The adherend was a copper foil / polyimide = 8 μm / 38 μm, Ni / Au plated two-layer FPC (pitch 50 μm, number of terminals 400) and ITO ( Indium / tin oxide) solid glass was used. These adherends were joined by the anisotropic conductive adhesive film obtained in each experimental example or experimental example.

Bonding strength was bonded under the condition that the temperature was raised to 170 ° C. for 10 seconds at 3 MPa, and evaluation was performed by a 90-degree peel test at a pulling speed of 50 mm / min. The adhesive force immediately after sample preparation was measured.

Connection reliability Crimping is performed under the condition that the temperature is increased to 170 ° C. for 10 seconds at 3 MPa, and the connection resistance between adjacent terminals immediately after sample preparation (initial) and after leaving for 1000 hours at 85 ° C. and 85% humidity is 2 terminals. Measured by the method. A contact resistance of less than 10.0Ω was evaluated as ◯ (good conduction) and 10.0Ω or more as x (defective conduction).

Preservability The anisotropic conductive adhesive was allowed to stand in an atmosphere at 25 ° C. for 2 weeks, and then pressure-bonded at 3 MPa to 170 ° C. for 10 seconds, and the connection resistance was measured. A value of less than 10.0Ω was evaluated as ◯ (good storage stability) and a value of 10.0Ω or more was evaluated as × (defective storage stability).

  From Tables 1 to 3, low-temperature short-time curability and storage are achieved by preheating the latent curing agent having a predetermined average particle diameter and capsule membrane material thickness at 40 ° C. for two days or longer at a low temperature for a long time. It was found that an anisotropic conductive adhesive film with good stability was obtained.

  Moreover, the LCD panel and COF were connected using the anisotropic conductive adhesive film which concerns on Experimental Examples 1-16, and the display apparatus member was obtained. The bonding conditions of the anisotropic conductive adhesive film were such that the temperature was raised to 170 ° C. at 3 MPa for 10 seconds. The obtained display device member was provided with peripheral members such as a power source and a backlight to obtain a liquid crystal display device.

In the obtained liquid crystal display device, good adhesion between the LCD panel and the COF was obtained. From this, it turned out that the anisotropic conductive adhesive film which concerns on Experimental Examples 1-16 can be utilized suitably as an anisotropic conductive adhesive film for an output.
This invention can also be set as the following aspects.
(1) (a) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and
(C) Conductive particles
An anisotropic conductive adhesive characterized in that the resin flow coefficient is 1.5 or more and 3.0 or less, and the tack after standing at 40 ° C. for 3 days is 70% or more of the tack before leaving Agent film.
Since the anisotropic conductive adhesive film of (1) has a resin flow coefficient of 1.5 or more and 3.0 or less, it is rapidly cured at a low temperature. Further, the tack after standing at 40 ° C. for 3 days is sufficiently large as 70% or more of the tack before storage, and the storage stability is excellent. For this reason, it has a structure excellent in low-temperature short-time curability and storage stability.
(2) (a) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and
(C) Conductive particles
As an essential component,
An anisotropic conductive adhesive film having a resin flow coefficient of 1.5 or more and 3.0 or less, and a resin flow coefficient after standing at 40 ° C. for 3 days is 70% or more of the resin flow coefficient before standing .
Since the anisotropic conductive adhesive film of (2) has a resin flow coefficient of 1.5 or more and 3.0 or less, it is rapidly cured at a low temperature. Further, the resin flow coefficient after standing at 40 ° C. for 3 days is sufficiently large as 70% or more of the resin flow coefficient before storage, and the storage stability is excellent. For this reason, it has a structure excellent in low-temperature short-time curability and storage stability.
(3) (a) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and
(C) Conductive particles
As an essential component, the resin flow coefficient is 1.5 or more and 3.0 or less, and the mixture of (b) the microencapsulated imidazole derivative epoxy compound and toluene is allowed to stand at 40 ° C. for 90 minutes. An anisotropic conductive adhesive film characterized by having a viscosity of 3 times or less of that before standing.
Since the anisotropic conductive adhesive film of (3) has a resin flow coefficient of 1.5 or more and 3.0 or less, it is rapidly cured at a low temperature. In addition, (b) the viscosity after leaving the mixture of the microencapsulated imidazole derivative epoxy compound and toluene for 90 minutes at 40 ° C. is not more than 3 times the viscosity before leaving, so the viscosity increase due to storage Sufficiently suppressed. For this reason, the solvent resistance of (b) the microencapsulated imidazole derivative epoxy compound is sufficiently ensured. Therefore, it has a configuration excellent in low-temperature short-time curability and storage stability.
(4) (a) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and
(C) Conductive particles
Is an essential component, and the reaction rate is 70% or more when pressure-bonded under a pressure of 3 MPa and heated to a pressure of 170 ° C. in 10 seconds. The tack after leaving at 40 ° C. for 3 days is not allowed to stand. An anisotropic conductive adhesive film characterized by being 70% or more of the tack of the above.
The anisotropic conductive adhesive film (4) has a sufficiently high reaction rate of 70% or more even under heat and pressure conditions of 3 MPa, 170 ° C., and 10 seconds, and cures rapidly at a low temperature. Further, the tack after standing at 40 ° C. for 3 days is sufficiently large as 70% or more of the tack before storage, and the storage stability is excellent. For this reason, it has a structure excellent in low-temperature short-time curability and storage stability.
(5) (a) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and
(C) Conductive particles
As a required component, the reaction rate when pressure-bonded under a pressure of 3 MPa under a heating and pressurizing condition where the temperature is raised to 170 ° C. in 10 seconds is 70% or more, and the resin flow coefficient after standing at 40 ° C. for 3 days is An anisotropic conductive adhesive film characterized by being 70% or more of a resin flow coefficient before being left.
The anisotropic conductive adhesive film of (5) has a sufficiently high reaction rate of 70% or more even under heat and pressure conditions of 3 MPa, 170 ° C., and 10 seconds, and cures quickly at low temperatures. Further, the resin flow coefficient after standing at 40 ° C. for 3 days is sufficiently large as 70% or more of the resin flow coefficient before storage, and the storage stability is excellent. For this reason, it has a structure excellent in low-temperature short-time curability and storage stability.
(6) (a) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and
(C) Conductive particles
As an essential component, the reaction rate when pressure-bonded under a pressure of 3 MPa and heated and pressurized to 10O 0 C in 10 seconds is 70% or more, and the microencapsulated imidazole derivative epoxy compound and toluene An anisotropic conductive adhesive film characterized in that the viscosity of the mixture obtained by leaving the mixture at 90 ° C. for 90 minutes is not more than 3 times the viscosity before standing.
The anisotropic conductive adhesive film of (6) has a sufficiently high reaction rate of 70% or more even under heat and pressure conditions of 3 MPa, 170 ° C., and 10 seconds, and cures quickly at a low temperature. In addition, (b) the viscosity after leaving the mixture of the microencapsulated imidazole derivative epoxy compound and toluene at 90 ° C. for 90 minutes is not more than 3 times the viscosity before leaving, so the viscosity increase due to storage It is sufficiently suppressed. For this reason, the solvent resistance of (b) the microencapsulated imidazole derivative epoxy compound is sufficiently ensured. Therefore, it has a configuration excellent in low-temperature short-time curability and storage stability.

It is sectional drawing which shows typically an example of a structure of the display apparatus of this invention. It is A-A 'sectional drawing of FIG.

Explanation of symbols

11 LCD panel 12 TCP
13 PCB
14 Anisotropic conductive adhesive 15 Conductive particles 16 Adhesive resin 17 ITO electrode 18 TCP electrode

Claims (10)

(A) epoxy resin,
(B) a microencapsulated imidazole derivative epoxy compound, and (c) conductive particles as essential components,
Before film formation, and characterized in that it comprises the (a) mixture 2 days or more heated the at a temperature of 35 ° C. or higher 60 ° C. or less as the epoxy resins (b) microencapsulated imidazole derivative epoxy compound An anisotropic conductive adhesive film. In the anisotropic conductive adhesive film according to claim 1,
An anisotropic conductive adhesive film having a resin flow coefficient of 1.5 or more and 3.0 or less. In the anisotropic conductive adhesive film according to claim 1,
An anisotropic conductive adhesive film having a reaction rate of 70% or more when pressure-bonded under a pressure of 3 MPa and heated and pressurized under a pressure of 3 MPa for 10 seconds. In the anisotropic conductive adhesive film according to claim 1,
An anisotropic conductive adhesive film characterized in that the tack after standing at 40 ° C for 3 days is 70% or more of the tack before leaving. In the anisotropic conductive adhesive film according to claim 1,
An anisotropic conductive adhesive film, wherein the resin flow coefficient after standing at 40 ° C. for 3 days is 70% or more of the resin flow coefficient before standing. In the anisotropic conductive adhesive film according to claim 1,
The anisotropic conductivity characterized in that the viscosity after leaving the mixture of (b) the microencapsulated imidazole derivative epoxy compound and toluene for 90 minutes at 40 ° C. is not more than 3 times the viscosity before standing Adhesive film.   The anisotropic conductive adhesive film according to any one of claims 1 to 6, wherein the average particle size of the (b) microencapsulated imidazole derivative epoxy compound is 0.1 µm or more and 3 µm or less. Conductive adhesive film.   8. The anisotropic conductive adhesive film according to claim 1, wherein the microcapsule wall material film of the (b) microencapsulated imidazole derivative epoxy compound has a thickness of 0.001 μm to 0.3 μm. An anisotropic conductive adhesive film characterized by that. In the anisotropic conductive adhesive film according to any one of claims 1 to 8,
(D) An anisotropic conductive adhesive film further comprising an elastomer having a nitrile group and an epoxy group.   10. The anisotropic conductive adhesive film according to claim 1, wherein the (a) epoxy resin includes an epoxy resin having a naphthalene skeleton. 11.

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