JP4113191B2 - Electronic equipment using anisotropic conductive film - Google Patents

Description

The present invention relates to an electronic device using an anisotropic conductive fill beam.

  In recent years, the need 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. As the connection method, a method of using a film-like anisotropic conductive film in which conductive particles are dispersed in an adhesive resin is used.

  In this method, a film of an anisotropic conductive film 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 there.

  The adhesive resin in the anisotropic conductive film is classified into a thermoplastic resin type and a thermosetting resin type. Recently, among these, a thermosetting resin type that is more reliable than a thermoplastic resin type is being widely used (Patent Document 1).

JP 05-021094 A

  However, the background art has problems in the following points. When trying to achieve fast curability at low temperatures, the storage stability decreases, and conversely, when the storage stability is improved, there is a problem that fast curability cannot be achieved at low temperatures. According to the present invention, low temperature rapid curability can be realized while maintaining storability.

The present invention relates to an electronic device in which a plurality of members are electrically joined with an adhesive, wherein the adhesive is: (A) a reactive elastomer, (B) an epoxy resin, (C) a microencapsulated imidazole derivative epoxy compound And (D) an anisotropic conductive film containing conductive particles as an essential component, wherein the organic solvent content in the anisotropic conductive film is 0.2 wt% or more and 2.0 wt% or less, wherein Ri der SP value of 7 to 11 of the organic solvent, the anisotropic conductive film, in connection resistance after compression under conditions of raising the temperature at 15 seconds to 170 ° C. is 3MPa less than 2.0Ω This is an electronic device .

  Conventional anisotropic conductive films are made into a product by almost evaporating an organic solvent in the drying step, and the amount of the organic solvent in the film is less than 0.1%. It was known that the amount of the organic solvent also fluctuated due to a slight variation in the drying conditions, but it was in the range where the amount of the organic solvent was less than 0.1%. By containing a certain amount as in the present invention, low temperature rapid curability can be realized while maintaining storability.

  The present invention is an anisotropic conductive film comprising (A) a reactive elastomer, (B) an epoxy resin, (C) a latent curing agent, and (D) conductive particles as essential components, and the anisotropic conductive film. The present invention relates to an anisotropic conductive film, wherein the organic solvent content in the conductive film is 0.1 to 5% by weight. The following is an example, and the present invention is not limited to the following. Below, each component of the anisotropic conductive film of this invention is demonstrated in detail.

  By including the reactive elastomer (A) used in the present invention, film formation can be reliably performed. Reactivity means having a functional group that reacts with other resin components in the anisotropic conductive film. Moreover, by using a reactive elastomer, the anisotropic conductive adhesive can be reliably formed into a film and formed into a sheet. 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 reactive elastomer is not particularly limited, but has a film-forming property, for example, 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 A copolymer, 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 a reactive elastomer is not specifically limited, It is preferable that it is 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. When the blending amount is not more than the upper limit value, the fluidity of the anisotropic conductive film is improved, and the connection reliability is improved. Moreover, wettability with various adherends is improved, and adhesion is improved. Moreover, the film forming property when it is set as an anisotropic conductive film as a compounding quantity is more than a lower limit will improve. Moreover, since the elasticity modulus of hardened | cured material becomes high, there exists a merit that the adhesiveness with respect to various to-be-adhered bodies improves, or the connection reliability after a thermal shock test improves.

  Further, as the reactive elastomer, a resin having a nitrile group, an epoxy group, or a hydroxyl 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.

  The (B) epoxy resin used in the present invention 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. From the viewpoint of curability, the epoxy equivalent is, for example, 100 g / eq or more and 500 g / eq or less. it can.

  (B) It is preferable that the compounding quantity of an epoxy resin is 50 to 2000 weight part with respect to 100 weight part of microencapsulated imidazole derivative epoxy compounds. When the blending amount is not more than the upper limit value, the curability when the anisotropic conductive film is obtained is improved. Moreover, heat resistance and moisture resistance improve that a compounding quantity is more than a lower limit, and the connection reliability when it is set as an anisotropic conductive film improves.

  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 film can be improved. Moreover, the linear expansion coefficient in the high temperature range of hardened | cured material can be reduced. The amount of the naphthalene-based epoxy resin added may be, for example, 5% by weight to 80% by weight, preferably 10% by weight to 50% by weight, based on the entire epoxy resin component in the anisotropic conductive film. By doing so, film formability and curing reactivity can be improved.

  The (C) latent curing agent used in the present invention is a mixture of an epoxy resin and a curing agent, which can be stored for a long time without changing its characteristics under a constant temperature condition. For example, when it is heated to a predetermined temperature, It is a curing agent that has a function of curing. Such a latent curing agent can be obtained, for example, by coating the curing agent with a polyurethane-based or polyester-based polymer material and encapsulating it. This is preferable because the pot life is extended.

  Specific examples of the curing agent include imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, dicyandiamide and the like. These can be used alone or in combination, and may be used by mixing a decomposition accelerator, an inhibitor and the like.

  The composition of the conductive particles (D) used in the present invention 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 film.

  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 thickness of the metal thin film is too thin, the connection becomes unstable when the anisotropic conductive film is formed, and if it is too thick, aggregation occurs. Therefore, when the anisotropic thin film is formed, insulation failure may occur. 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 blending amount of (D) conductive particles used in the present invention is, for example, 0.05% by volume or more and 5% by volume with respect to the total of (A) reactive elastomer, (B) epoxy resin, and (C) latent curing agent. It can be as follows. When the blending amount is less than or equal to the upper limit value, the absolute amount of conductive particles in the anisotropic conductive film becomes an appropriate amount, so that the insulation between the adherend connection terminals is improved. On the other hand, if the blending amount is at least the lower limit value, the absolute amount of conductive particles in the anisotropic conductive film becomes an appropriate amount, the conductive particles on the adherend connection terminal are improved, and the connection resistance value is lowered.

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

  Furthermore, the anisotropic conductive adhesive according to the present invention has various additives such as a non-reactive diluent, a reactive diluent, etc. for improving various properties such as resin compatibility, stability, and workability. A thixotropic agent, a thickener, an inorganic filler and the like may be added as appropriate.

Examples of solvents that can be used in the present invention are listed below together with their SP values. The SP value (solubility parameter) is an index indicating the polarity of a substance.
Dimethylsiloxane (5.5), dichlorodifluoromethane (5.5), neopentane (6.3), diisopropyl ether (6.9), 1-nitrooctane (7.0), n-pentane (7.0) N-hexane (7.3), diethyl ether (7.4), n-octane (7.6), isoamyl acetate (7.8), diisobutyl ketone (7.8), cyclohexane (8.2), Isobutyl acetate (8.3), isopropyl acetate (8.4), methyl isopropyl ketone (8.5), butyl acetate (8.5), carbon tetrachloride (8.6), propylbenzene (8.6) methyl Propyl ketone (8.7), ethylbenzene (8.8), xylene (8.8), p-chlorotoluene (8.8), toluene (8.9), ethyl acetate (9.1), tetrahydrofuran ( .1), benzene (9.2), trichloroethyl (9.2), styrene (9.3), methyl ethyl ketone (9.3), chloroform (9.3), methylene chloride (9.7), acetone ( 9.9), cyclohexanone (9.9), carbon disulfide (10.0), acetic acid (10.1), m-cresol (10.2), aniline (10.3), 1-octanol (10. 3), cyclopentanone (10.4), ethylene glycol monoethyl ether (10.5), t-butyl alcohol (10.6), pyridine (10.7), n-hexanol (10.7), 1 -Pentanol (10.9), cyclohexanol (11.4), n-butanol (11.4), isopropyl alcohol (11.5), acetonitrile (11.9), dimethylformamide 12.0), benzyl alcohol (12.1), diethylene glycol (12.1), nitromethane (12.7), ethanol (12.7), methanol (14.5), ethylene glycol (14.6), glycerol (16.5), formamide (19.2) and the like can be used, and these can be used alone or in admixture of two or more.

  In the present invention, the SP value of the organic solvent in the anisotropic conductive film is preferably 7 or more, more preferably 8 or more, preferably 11 or less, more preferably 10 or less. When the SP value of the organic solvent is within this range, the coating resin of the component (C) latent curing agent can be efficiently swollen, and as a result, the curability can be appropriately improved.

  In the present invention, the organic solvent content in the anisotropic conductive film is preferably 0.3 to 3% by weight. When it is at least the lower limit, the curability is improved, and when it is at most the upper limit, the preservability is improved.

  Conventional anisotropic conductive films are made into a product by almost evaporating an organic solvent in the drying step, and the amount of the organic solvent in the film is less than 0.1%. Since the drying conditions are not always constant, the amount of the organic solvent in the anisotropic conductive film may vary, but the amount of the organic solvent is less than 0.1%, as in the present invention. A certain amount or more of the organic solvent was not included in the film. The reason for this is that if an organic solvent is contained in a large amount in the anisotropic conductive film, tackiness occurs in the film, and workability is lowered, and in addition, storage stability is increased in order to activate the latent curing agent unnecessarily. It is because it has been thought that it will also reduce. The inventors of the present application have completed the present invention by paying attention to the fact that, by containing a certain amount of an organic solvent having a specific SP value in the film, it is possible to achieve low-temperature rapid curability while maintaining storability.

  The amount of the organic solvent in the present invention is not an intermediate stage for producing the anisotropic conductive film but an amount in the final product.

  The anisotropic conductive film according to the present invention is obtained, for example, as follows. First, a resin varnish obtained by uniformly dispersing a raw material resin is applied onto a polyethylene terephthalate subjected to a release treatment so that the thickness after drying is 45 μm and dried. The amount of organic solvent can be adjusted by changing the drying temperature and drying time at this time. Thereafter, the dried product is cut into, for example, a width of 2.0 mm to obtain an anisotropic conductive film.

(Example 1)
As shown in Table 1, bisphenol A type phenoxy resin (ethyl acetate 20% solution) 150 parts by weight, polyvinyl butyral resin (ethyl acetate 20% solution) 50 parts by weight, epoxy group represented by the above general formula (1) Containing acrylic rubber (ethyl acetate 20% solution, R ₁ = C ₂ H ₅ , R ₂ = CH ₃ , molecular weight 700,000 in the above general formula (1)) 50 parts by weight, bisphenol A type epoxy resin 20 parts by weight 30 parts by weight of microencapsulated 2-methylimidazole derivative epoxy compound, 2 parts by weight of nickel / gold plated benzoguanamine resin particles, 5 parts by weight of silane coupling agent, 350 parts by weight of toluene, and 150 parts by weight of ethyl acetate Were uniformly dispersed. Moreover, the obtained resin varnish was apply | coated so that the thickness after drying might be set to 45 micrometers on the polyethylene terephthalate which gave the mold release process, and it dried. Drying was performed by exposing the coated surface for 360 seconds in a drier having an internal temperature of 60 ° C. and a wind speed of 15 m / min. The dried product was cut into a width of 2.0 mm to obtain an anisotropic conductive film.

(Measurement method of organic solvent in anisotropic conductive film)
About 5 mg of anisotropic conductive resin sample is placed in a purge & trap (Nippon Analytical Chemistry JHS-100A type) sample tube, and the sample is heated at 200 ° C. for 15 minutes while expelling volatiles with helium gas at a flow rate of 50 ml / min. did. The volatile matter generated at this time is trapped at −80 ° C., and the components trapped after the heating of the sample are applied to GC / MS (GC: Hewlett Packard HP-5890 gas chromatograph, MS: Hewlett Packard HP-5970B mass detector). Introduced. Assignment of each peak in the chromatogram was performed based on the respective mass spectrum. In addition, about the fixed_quantity | quantitative_assay of a detection component, 0.5 microliters of acetone dilution solutions of the standard sample of a known density | concentration were inject | poured, measured like the sample, and quantified using the peak area value.

(Preparation of evaluation sample)
A sample for evaluation was prepared in advance as follows. Copper foil / polyimide = 25/75 μm with 0.5 μm tin plated TCP (pitch 0.30 mm, 60 terminals), 0.8 mm thick 4-layer board (FR-4) inner layer, outer layer copper foil 18 μm Flash gold-plated PCB (pitch 0.30 mm, number of terminals 60) was joined with the anisotropic conductive film obtained in each experimental example.

(Adhesive strength)
Pressure bonding was performed under the condition that the temperature was increased to 170 ° C. for 15 seconds at 3 MPa, and evaluation was performed by a 90 ° peel test at a pulling speed of 50 mm / min. The adhesive force immediately after sample preparation was measured.

(Connection reliability)
Bonding was performed under the condition that the temperature was raised to 170 ° C. for 15 seconds at 3 MPa, and the connection resistance was measured immediately after the sample was prepared and after being left at a temperature of 85 ° C. and a humidity of 85% for 500 hours (after HH treatment). A case where the connection resistance was less than 2.0Ω was evaluated as “Good” (conducting good), a case where it was 2.0Ω or more and less than 5.0Ω, and a case where it was 5.0Ω or more were evaluated as “Poor” (conducting failure).

(Storability)
The anisotropic conductive film was allowed to stand in an atmosphere of 40 ° C. for 3 days, and then pressure-bonded at 3 MPa to 170 ° C. for 15 seconds, and the connection resistance was measured. A case where the connection resistance was less than 2.0Ω was evaluated as “Good” (conducting good), a case where it was 2.0Ω or more and less than 5.0Ω, and a case where it was 5.0Ω or more were evaluated as “Poor” (conducting failure).

(Workability)
When the product was pulled out from the reel, the stickiness of the resin was strong, and the case where reverse transfer or floating from the base material occurred was rated as x, and the case where it did not occur was marked as ◯.

(Examples 2 to 5, Comparative Example 1)
The experiment was conducted by changing the solvent and drying conditions of Example 1 as shown in Table 1. The results are shown in Table 1.

In Table 1, the raw materials used are shown below.
(1) Bisphenol A type phenoxy resin, PKHC manufactured by Inchem (20% ethyl acetate solution)
(2) Polyvinyl butyral resin, BX-1 manufactured by Sekisui Chemical Co., Ltd. (20% ethyl acetate solution)
(3) Epoxy group-containing acrylic rubber (20% ethyl acetate solution, R ₁ = C ₂ H ₅ , R ₂ = CH ₃ in the above general formula (1), molecular weight 700,000)
(4) Bisphenol A type epoxy resin, Epicoat 828 manufactured by Japan Epoxy Resin Co., Ltd.
(5) Microencapsulated-2-methylimidazole derivative epoxy compound, HX-3941HP manufactured by Asahi Kasei Chemicals
(6) Nickel / gold plating coated benzoguanamine resin particles, 20GNR4.6-EH manufactured by Nippon Chemical Industry Co., Ltd.
(7) Silane coupling agent, Shin-Etsu Chemical KBM-403E

From Table 1, in Examples 1-6, it turned out that the anisotropic conductive film which is excellent in adhesive strength, preservability, and workability | operativity is obtained.
Comparative Example 1 is a conventional product with a low organic solvent content of 0.03%. Although there was no problem in storage stability and workability, the adhesive strength was low, and defects occurred in connection reliability after HH treatment. Furthermore, when a sample having an organic solvent amount of 5.0% was prepared and evaluated, it was inferior to the result of the organic solvent amount of 2.0% in Example 3, but any of adhesive strength, connection reliability, storage stability, and workability. However, there was no problem.

(Example of use in electronic equipment)
Moreover, PCB and TCP were connected using the anisotropic conductive film which concerns on Experimental Examples 1-6, and the display apparatus member was obtained. The anisotropic conductive film was bonded under conditions of 3 MPa at 170 ° C. for 15 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 PCB and TCP was obtained. From this, it turned out that the anisotropic conductive film which concerns on Experimental Examples 1-6 can be utilized suitably as an anisotropic conductive film for input.

  The present invention is used for anisotropic conductive films and electronic devices using the same.

Claims (1)

In an electronic device in which a plurality of members are electrically joined by an adhesive,
The adhesive is
(A) a reactive elastomer,
(B) epoxy resin,
(C) an anisotropic conductive film comprising a microencapsulated imidazole derivative epoxy compound and (D) conductive particles as essential components,
The anisotropically conductive organic solvent content in the film is 2.0 wt% or less than 0.2 wt% state, and are SP value of 7 to 11 of the organic solvent,
An electronic device characterized in that the anisotropic conductive film has a connection resistance of less than 2.0Ω after being pressure-bonded under the condition that the temperature is raised to 170 ° C. for 15 seconds at 3 MPa .