KR20090114232A - Anisotropic Conductive Film Having Property Stability And Circuit Board Using The Same - Google Patents

Abstract

PURPOSE: An anisotropic conductive adhesive is provided to ensure excellent storage stability and temporal stability because temporal phenomenon is not generated during room temperature storage in summer. CONSTITUTION: An anisotropic conductive adhesive comprises a thermoplastic resin for film formation, a thermosetting resin as a binder, a hardener, conductive particles, and adhesion improver. The PH value of the anisotropic conductive adhesive satisfies ??H < 2, wherein ??H=1PHacf-PHref1, 6.5 <PHref <7.5, ??H is a PH deviation, PHref is a reference PH, and PHacf is the PH of the anisotropic conductive adhesive.

Description

Anisotropic Conductive Film Having Property Stability And Circuit Board Using The Same

The present invention relates to an anisotropic conductive film used for connecting circuit boards or electronic components such as IC chips and wiring boards, and a circuit connection structure using the same. It relates to an excellent anisotropic conductive film.

In order to electrically connect circuit boards or electronic components, such as an IC chip, and a circuit board, the anisotropic conductive film in which the electroconductive particle is disperse | distributed to the adhesive agent is used. In this case, the anisotropic conductive film is disposed between the electrodes facing each other, and the electrodes are connected by heating and pressurization, and then electrically connected by making the conductive in the pressing direction. Such anisotropic conductive films are typically used for packaging LCD panels, printed circuit boards (PCBs), and driver ICs.

Currently, LCDs are applied to a wide range of applications from large panels for notebook PCs, monitors, and televisions to medium and small panels for mobile devices such as mobile phones, personal digital assistants (PDAs), and handheld game consoles. The mounting of the driver IC by a film is employ | adopted. Driver IC mounting in LCDs uses an OLB (Outer Lead Bonding) method or a printed circuit board that converts the driver IC into a Tape Carrier Package (TCP) or a Chip On Film (COF) and adheres it to the LCD panel. PCB: PCB type is attached to the printed circuit board. In addition, in small and medium sized LCDs such as mobile phones, a COG (Chip On Glass) method is adopted in which a driver IC is directly mounted on an LCD panel by an anisotropic conductive film.

As such, anisotropic conductive films widely used in flat panel displays and mobile devices require excellent workability, conductivity and high adhesive strength, as well as excellent time stability. That is, even after curing, deterioration does not occur over time or should be less.

Accordingly, various efforts have been made to improve the stability of the anisotropic conductive film over time.

The present inventors have found that the time-lapse stability of the anisotropic conductive film is closely related to the pH of the ACF composition. In particular, the closer the pH of the ACF composition is to neutral, the better the stability of the ACF over time.

Therefore, an object of the present invention is to provide an anisotropic conductive film having excellent stability over time.

In addition, another object of the present invention is to determine the PH conditions of the anisotropic conductive film having excellent stability over time.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The anisotropic conductive adhesive having excellent stability over time has little change in physical properties (adhesive force, connection resistance, DSC calorie change, etc.) with time even when stored at room temperature. The stability over time of the anisotropic conductive adhesive is closely related to the PH condition of the anisotropic conductive adhesive composition, and particularly, the higher the PH value of the anisotropic conductive adhesive composition is 5 to 9, the better the stability over time.

That is, as the PH value of the manufactured anisotropic conductive adhesive converges to the reference PH (PHref: 6.5 <PHref <7.5), the stability over time is excellent. Therefore, the PH deviation (ΔPH) of the anisotropic conductive adhesive having excellent stability over time should satisfy the following equation (1).

△PH ＜ 2 (△PH = , 6.5 ＜PHref ＜7.5)

ΔPH <2 (△ PH =, 6.5 <PHref <7.5)

(Where, △ PH: PH deviation, PHref: reference PH, PHacf: PH of anisotropic conductive adhesive)

The anisotropic conductive adhesive having a PH value having a PH deviation of less than 2 has a very stable stability over time because the change in curing rate is within 10% even after 14 days at a temperature of 30 ° C. and a relative humidity of 60%. outstanding. In addition, the storage stability is also excellent because the aging does not occur even when stored at room temperature on a summer basis.

The anisotropic conductive film according to the present invention is excellent in stability over time because there is no significant change in adhesion, connection resistance and DSC calories even after storing for a long time.

Hereinafter, the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals indicate the same or equivalent components.

1 shows a state in which anisotropic conductive film 10 according to the present invention is interposed between circuit boards 20 and 30 facing each other.

The anisotropic conductive film 10 is prepared by applying an anisotropic conductive adhesive consisting of a thermoplastic resin for forming a film, a thermosetting resin as a binder, a curing agent, conductive particles and other additives on a release film, and drying.

Examples of the thermoplastic resin include polyvinyl butyral, polyvinyl formal, polyvinyl acetal, polyamide, phenoxy resin, poly monkeyphone, styrene-butadiene-styrene block copolymer, carboxylated styrene-ethylene-butylene-styrene A block copolymer, polyacrylate resin, etc. can be used 30 to 60 weight%.

As the thermosetting resin, an epoxy resin or an acrylate monomer may be used.

Preferred examples of the epoxy resin include polyvalent epoxy resins having two or more glycidyl groups in one molecule. For example, bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins, and biphenyls. 5 to 45 weight% can be used individually or in mixture of a type | mold epoxy resin, a dicyclopentadiene type epoxy resin, and a naphthalene type epoxy resin.

At this time, the curing agent is preferably a curing agent for epoxy resin, in particular, imidazole compound, amine-based as a latent curing agent excellent in storage stability, fast curing speed From compounds, acid anhydride compounds, polyamide compounds and isocyanate compounds Preference is given to using at least one selected. Specifically, dicumyl peroxide, thi-butyl- cumyl peroxide, bis (alpha-thi-butyl peroxyisopropyl) benzene, 2,5-di (thi-butylperoxy) -2,5- Dimethylhexine-3, diterbutylperoxide, 1,1-di (terbutylperoxy) -3,3,5-trimethylcyclohexane, en-butyl-4,4-di- (terbutylper Oxy) vallate, 1,1-di-terbutylperoxycyclohexane, isopropylcumylterbutylperoxide, bis (alpha-teramylperoxyisopropyl) benzene, imidazole, 2-ethyl imidazole, 2- Phenyl-4-methyl imidazole, 2-dodecyl imidazole, 2-phenyl imidazole, 2-phenyl-4-methyl imidazole, 4-methyl imidazole, boron trifluoride-amine complex, sulfonium salt, amineimide , And a composition selected from salts of polyamines, dicyandiamides and the like can be used alone or in a mixture of 0.1 to 20% by weight.

As the acrylate monomer, a radical polymerizable resin having a functional group polymerized by a radical such as an acrylic monomer, a methacryl monomer, a maleimide compound, an unsaturated polyester, acrylic acid, vinyl acetate, and acrylonitrile is used. Examples include methyl acrylate, ethyl acrylate, bisphenol A-ethylene glycol modified diacrylate, isocyanuric acid ethylene glycol modified diacrylate, pentaerythritol triacrylate, trimetholpropane triacrylate, and trimetholpropane propylene. Glycol modified triacrylate, isocyanuric acid ethylene glycol modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, dicyclopentenyl acrylate, tricyclodecanyl Akleilay Ethylene isoamyl acrylate, lauryl acrylate, stearyl acrylate, butoxy ethyl acrylate, ethoxy diethylene glycol acrylate, methoxy triethylene glycol acrylate, methoxy polystyrene glycol acrylate, methoxy Dipropylene glycol acrylate, phenoxy ethyl acrylate, phenoxy polystyrene glycol acrylate, isobornyl acrylate, 2-hydroxy ethyl acrylate, 2-hydroxy propyl acrylate, methyl methacrylate, isobutyl Methacrylate, tridecyl methacrylate, methoxy diethylene glycol methacrylate, methoxy polystyrene glycol methacrylate, perryl methacrylate, perryl acrylate, isobutyl acrylate, isobornyl methacrylate Methoxy triethylene glycol methacrylate, etc. These may be used alone or in combination of two or more thereof. At this time, the acrylate monomer is preferably contained 30 to 70% by weight.

In addition, as the curing initiator for the acrylate monomer, an azo compound, an organic peroxide may be used. Specifically, dicanoyl peroxide, benzoyl peroxide, dicumyl peroxide, dibutyl peroxide, cumene hydroper Oxide, t-butyl-cumylperoxide, bis (alpha-thi-butylperoxyisopropyl) benzene, 2,5-di (thi-butylperoxy) -2,5-dimethylhexane , 2,5-di (thi-butylperoxy) -2,5-dimethylhexine-3, diterbutylperoxide, 1,1-di-terbutylperoxycyclohexane, isopropylcumylterbutyl A composition selected from peroxides, bis (alpha-teramylperoxyisopropyl) benzene and the like can be used alone or in combination. At this time, the curing initiator is preferably contained 0.1 to 30% by weight.

The said electroconductive particle is for electrically connecting a to-be-connected body, such as a microcircuit electrode, and can use a wide range of particle | grains which are high in melting | fusing point and hardness, and excellent in electroconductivity. Such conductive particles include gold (Au), silver (Ag), iron (Fe), copper (Cu), nickel (Ni), cadmium (Cd), bismuth (Bi), indium (In), aluminum (Al), palladium (Pd), platinum (Pt), chromium (Cr) and the like coated polystyrene, polymethacrylate, polymethyl methacrylate, polyvinylacetate, divinylbenzene, benzoguanamine and the like. As the conductive particles of the present invention, silver powder or nickel powder may be used as it is. At this time, the conductive particles have a uniform particle size distribution within ± 0.1㎛ particle size, and use a diameter of 2.5 ~ 20㎛, so that the density of the conductive ball in the anisotropic conductive adhesive is 4,000 ~ 12,000 / mm2.

In addition, a silane coupling agent or the like may be used as an additive as an adhesion promoter, and the silane coupling agent is used to adjust the PH of the anisotropic conductive adhesive. For example, 3-aminopropyltriethoxysilane, 3- (trimethoxysilyl) propyl methacrylate [3- (trimethoxysilyl) propyl methacrylate], etc. may be used as the silane coupling agent. .

When the pH of the anisotropic conductive adhesive is close to acidic, it is possible to add a basic amine compound as the silane coupling agent to make the PH neutral while maintaining the adhesive force of the anisotropic conductive adhesive. In addition, when PH of an anisotropically conductive adhesive is near basic, it can neutralize using an acid catalyst.

As described above, the pH of the anisotropic conductive adhesive is most easily controlled using a silane coupling agent which is a kind of additive, but is not necessarily limited thereto. That is, it is also possible to adjust the PH of the composition itself by mixing suitably the thermoplastic resin which comprises an anisotropic conductive adhesive, a thermosetting resin, a hardening | curing agent.

Hereinafter, a plurality of anisotropic conductive adhesives having various PH values were prepared, and the anisotropic conductive adhesives were applied onto a release film, and dried to prepare a plurality of anisotropic conductive films. Then, the stability over time was tested for the anisotropic conductive film thus prepared, and the results are summarized in a table.

[Production of Anisotropic Conductive Adhesive]

An adhesive composition composed of a thermoplastic resin for forming a film, an epoxy thermosetting resin (or acrylate monomer) as a binder, a curing agent (or a curing initiator), is dissolved or dispersed in an organic solvent, furthermore, conductive particles are dispersed, and as an adhesion promoter. The silane coupling agent is suitably added to prepare an ACF composition having the desired PH value. The organic solvent used at this time is preferable because the mixed solvent of an aromatic hydrocarbon type and an oxygen type improves the solubility of a material.

10 g of ACF thus prepared was dissolved in 250 g of methyl-ethyl-ketone (MEK), and the pH value was measured using a PH meter.

[Production of Anisotropic Conductive Film]

The anisotropic conductive adhesive composition prepared above is apply | coated to the transparent PET film which surface-treated the single side | surface using a potter's finger, and obtains an anisotropic conductive film by hot air drying of 70 degreeC and 10 minutes.

[Manufacture of circuit connection structure]

2 illustrates an OLB method or a PCB method of connecting a COF or TCP to a glass substrate or a PCB substrate through an anisotropic conductive film.

As shown in the drawing, the anisotropic conductive film 10 prepared above was placed on a glass substrate or a PCB substrate 31 and pressed under a pressure of 1 MPa to 3.5 MPa for 0.5 seconds to 3 seconds in a temperature range of 65 ° C. to 90 ° C. Then, COF or TCP 22 is disposed on the anisotropic conductive film. Subsequently, the circuit was heated and pressurized for 10 seconds at a temperature of 180 ° C. and 2 MPa to 4 MPa using a heating bar 41 on a COF or TCP 22 through a buffer 42 made of 0.15T Teflon sheet. Manufacture connection structure.

At this time, the anisotropic conductive film used for the circuit connection structure is manufactured to have a different PH value as follows. At this time, ten identical samples were produced for each Example and Comparative Example, and the DIC indentation, the connection resistance, the adhesive strength, and the DSC calorific value were measured for each, and the average value was obtained and summarized in a table.

Example 1

An anisotropic conductive film having a thickness of 19 mm and an initial PH value of 6.32 was produced, and the anisotropic conductive film was applied to the circuit connection structure.

Example 2

An anisotropic conductive film having a thickness of 18 mm and an initial PH value of 5.4 was produced, and the anisotropic conductive film was applied to the circuit connection structure.

Example 3

An anisotropic conductive film having a thickness of 21 mm and an initial PH value of 8.43 was produced, and the anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 1

An anisotropic conductive film having a thickness of 20 mm and an initial PH value of 3.32 was produced, and the anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 2

An anisotropic conductive film having a thickness of 19 mm and an initial PH value of 10.35 was produced, and the anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 3

An anisotropic conductive film having a thickness of 21 mm and an initial PH value of 2.24 was produced, and the anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 4

An anisotropic conductive film having a thickness of 18 mm and an initial PH value of 12.54 was produced, and the anisotropic conductive film was applied to the circuit connection structure.

The anisotropic conductive film and the circuit connection structure intervening the anisotropic conductive film produced through the above-described examples and comparative examples as follows (1) conduction reliability test, (2) DIC indentation test, (3) adhesive strength test and (4) DSC calorimetry change test was done, and the result is shown in Table 1.

(1) conduction reliability test

Using a multimeter, the initial resistance (저항 _i ) and the resistance (Ω _f ) after storage for 7 days at 30 ° C. and 60% relative humidity were measured and displayed.

(2) DIC Indentation Test

When the electrode of the glass substrate bonded to the chip is an ITO transparent electrode, the conductive ball pressing phenomenon was observed through an optical microscope, and in the case of the chromium electrode, the DIC indentation was observed using a differential interference microscope.

At this time, if the deformation of the conductive ball is observed in the ITO transparent electrode, ○, if there is no deformation of the conductive ball, it is indicated by ×, and if the protrusion of the conductive ball is observed in the chromium electrode, ○, there is no derivation of the conductive ball. In the case, X was indicated.

(3) adhesive strength test

After pressing the anisotropic conductive film in the form of TCP or COF on a glass substrate or a PCB substrate, the adhesive force was measured and displayed by pulling in a direction perpendicular to the substrate at a speed of 50 mm / min using an IMADA push-pull gauge. At this time, the adhesive strength was measured separately from the initial adhesive strength and after 7 days storage at 30 ℃ and 60% relative humidity conditions separately.

(4) DSC calorie change test

Differential scanning for the produced anisotropic conductive film samples, anisotropic conductive film samples after 7 days storage at 30 ° C. and 60% relative humidity conditions, and anisotropic conductive film samples after 14 days storage at 30 ° C. and 60% relative humidity conditions DSC calorimetry was measured and displayed using a differential scanning calorimeter.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4  Initial sample DIC Indentation ○ ○ ○ ○ ○ × × Connection resistance (Ω) 1.2 1.2 1.2 1.5 1.7 2.1 2.4 Adhesion Strength (kgf / cm) 1230 1142 1320 980 876 781 821 Calories (J / g) 137.9 137.1 145.7 138.2 142.9 139.4 144.5  7 days archive sample DIC Indentation ○ ○ ○ × × × × Connection resistance (Ω) 1.2 1.3 1.2 open open open open Adhesion Strength (kgf / cm) 1289 1231 1276 326 228 146 129 Calories (J / g) 137.3 137 144.4 130.4 135.6 128.2 132.5 14 days archive sample  Calories (J / g) 136.8 136.5 142.6 122.5 127.2 121.3 124.4

As can be seen from Table 1, the anisotropic conductive films of Examples 1 to 3 have no change in DIC indentation, adhesive strength and connection resistance even after storage for 7 days at 30 ° C. and 60% relative humidity. It can be confirmed that the change in DSC calorimetry measured after 14 days storage at 60 ° C. and 60% relative humidity is within 10%.

On the other hand, in the anisotropic conductive films of Comparative Examples 1 to 4 after 7 days at 30 ° C. and 60% relative humidity conditions, connection reliability deteriorates (that is, no conductive ball crushing phenomenon is observed, and connection resistance Can not be measured), the adhesive strength is significantly reduced. In addition, when 14 days were left under conditions of 30 degreeC and 60% relative humidity, a DSC calorie change exceeds 10%. That is, it can be confirmed that a considerable degree of deterioration has progressed in the anisotropic conductive films of Comparative Examples 1 to 4.

, 6.5 ＜PHref ＜7.5)(여기서, △PH : PH 편차, PHref : 기준 PH, PHacf : 이방 도전 접착제의 PH)가 2를 넘지 않는 이방 도전 접착제를 이용하여 제작한 이방 도전 필름은 상온에서 오랫동안 보관하여도 열화의 정도가 낮거나 없고, 접속 신뢰성이나 접착 강도와 같은 물성 변화가 거의 없어 경시 안정성이 매우 우수함을 알 수 있다. Thus, PH deviation (ΔPH =

Anisotropic conductive film produced using an anisotropic conductive adhesive having no greater than 2, 6.5 <PHref <7.5) (wherein ΔPH: PH deviation, PHref: reference PH, PHacf: PH of anisotropic conductive adhesive) is stored at room temperature for a long time. Even if the degree of deterioration is low and there is little change in physical properties such as connection reliability and adhesive strength, it can be seen that stability with time is excellent.

The following drawings attached to this specification are illustrative of the preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a state diagram in which an anisotropic conductive film is interposed between opposing circuit members.

2 is a connection process diagram for bonding COF or TCP to a glass substrate or a PCB via an anisotropic conductive film.

<Explanation of symbols for the main parts of the drawings>

10: anisotropic conductive film 31: glass substrate or PCB

22: COF or TCP 41: Heating bar

42: cushioning material

Claims (13)

In the anisotropic conductive adhesive comprising a thermoplastic resin for forming a film, a thermosetting resin, a curing agent, conductive particles and an adhesion promoter as a binder, PH value of the anisotropic conductive adhesive satisfies the following conditions.  ΔPH <2 (△ PH =

, 6.5 <PHref <7.5) (Where, △ PH: PH deviation, PHref: reference PH, PHacf: PH of anisotropic conductive adhesive) The method of claim 1, The thermosetting resin is an epoxy resin, characterized in that the anisotropic conductive adhesive. The method of claim 1, The thermosetting resin is an acrylate monomer, characterized in that the anisotropic conductive adhesive. The method of claim 2 or 3, An anisotropic conductive adhesive, characterized in that the adhesion promoter is a silane coupling agent. The method of claim 4, wherein The diameter of the said electroconductive particle is 2.5-20 micrometers, and the density is 4,000-12,000 piece / mm <2>, The anisotropic conductive adhesive characterized by the above-mentioned. The anisotropic conductive film of Claim 1 was apply | coated to a release film, and it dried and manufactured, The anisotropic conductive film characterized by the above-mentioned. The method of claim 6, An anisotropic conductive film, wherein the change in curing rate is less than 10% after 14 days in a state of being opened at 30 ° C. and 60% relative humidity. The method of claim 7, wherein The thermosetting resin is an anisotropic conductive film, characterized in that the epoxy resin. The method of claim 7, wherein The anisotropic conductive film, characterized in that the thermosetting resin is an acrylate monomer. The method according to claim 8 or 9, The anisotropic conductive film, characterized in that the adhesion promoter is a silane coupling agent. The method of claim 10, Anisotropic conductive film, characterized in that the diameter of the conductive particles is 2.5 ~ 20㎛, the density is 4,000 ~ 12,000 / mm2. A circuit connecting structure electrically and mechanically connected between a first circuit member and a second circuit member by thermocompression bonding through the anisotropic conductive film of claim 6 or 7. The method of claim 12, The first circuit member is a Tape Carrier Package (TCP) or a Chip On Film (COF), and the second circuit member is a glass substrate or a printed circuit board (PCB).

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