KR101184910B1 - Anisotropic conductive adhesive having superior repairability and fast adhesiveness - Google Patents

Abstract

Disclosed are an anisotropic conductive adhesive used for electrical connection of a fine circuit, such as a connection between a liquid crystal display and a tape carrier package (TCP), and a connection between a TCP and a printed circuit board. The anisotropic conductive adhesive is a radical polymerizable resin; Organic peroxides; Thermoplastic elastomers; Urethane prepolymers; Reactive polymer resins; Electroconductive particle; And a particulate core / shell-type rubber, wherein the content of the organic peroxide is 1 to 10 parts by weight, and the content of the thermoplastic elastomer is 10 to 200 parts by weight, based on 100 parts by weight of the radically polymerizable resin. The content of the urethane prepolymer is 10 to 100 parts by weight, the content of the reactive polymer resin is 10 to 200 parts by weight, the content of the conductive particles is 1 to 30 parts by weight, and the content of the particulate core / shell rubber is 1 To 30 parts by weight.

Electrical connection, anisotropic conductivity, adhesive

Description

Anisotropic conductive adhesive having superior repairability and fast adhesiveness}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic conductive adhesive, and more particularly, to an anisotropic conductive adhesive used for electrical connection of a microcircuit such as a liquid crystal display and a tape carrier package (TCP), a TCP and a printed circuit board, and the like. It is about.

In recent years, the necessity of the connection of various microcircuits, such as the connection of a flat panel display, such as a liquid crystal display (LCD), a plasma display, and a tape carrier package (TCP), and the connection of a TCP and a printed circuit board (PCB), is increasing, The connection method As an example, the anisotropic conductive adhesive which disperse | distributed electroconductive particle in adhesive resin is used widely. In a circuit connecting method using an anisotropic conductive adhesive, an anisotropic conductive adhesive is placed between members to be connected and heated and pressed to electrically conduct terminals in the vertical direction while maintaining electrical insulation between the terminals in the surface direction. . When using a conventional connection method such as soldering, when connecting a substrate or a minute circuit without heat resistance, such as TCP and PCB, there is a problem that the adjacent terminals are electrically shorted, whereas when using an anisotropic conductive adhesive, the adjacent terminals While suppressing the electrical short, there is an advantage that a large number of electrodes can be connected at one time.

Anisotropic conductive adhesives can be classified into a thermoplastic type and a thermosetting type, and recently, an epoxy resin-based thermosetting type adhesive having superior reliability than a thermoplastic type has been widely used. The thermoplastic type adhesive mainly uses styrene copolymers such as SBS (styrene butadiene styrene), SIS (styrene isoprene styrene), SEBS (styrene ethylene butadiene styrene), chloroprene rubber, phenol resin mixtures and the like. Thermoplastic adhesives basically use a heat fusion method, and under general conditions, low temperature and short time adhesion can be achieved in comparison with thermosetting adhesives. It tends to be low and long term durability.

On the other hand, the thermosetting type anisotropic conductive adhesive generally uses epoxy resin adhesive resin which is excellent in the balance of storageability, stability, and curability. In the case of the thermosetting adhesive, it is necessary to heat and cure around 10 seconds at a temperature of 180 to 200 ° C. in order to achieve both the storage stability and the curability of the resin. There is a disadvantage that is difficult to cure. Further, when in order to improve the storage stability, for example, BF ₃ amine complexes, dicyandiamide, organic acid Hydra Zaid, the system has already been blended with a latent curing agent such as imidazole compounds have been proposed, improved storage stability, but the cure When a long time or a high temperature is required, on the contrary, when hardening in low temperature and a short time, there existed a problem to fall in storage stability.

In recent years, with the tendency for the large screen, high precision of an LCD module, and the edge of a frame becoming thin, the connection pitch becomes small and connection narrows rapidly. For this reason, for example, when the LCD and the TCP are connected, the TCP expands due to heat to cause a difference in the connection pattern, or because the connection part is narrow, a problem occurs in which the LCD inner member is thermally affected by the heat during the connection. have. In addition, in the connection between the TCP and the PCB, as the length of the PCB increases, the PCB and the LCD bend due to the heating at the time of connection, thereby causing a problem that the wiring of the TCP is disconnected. In order to solve this problem, a method of connecting the microcircuit at low temperature can be considered. For example, when a circuit is connected using a thermoplastic type anisotropic conductive adhesive, the connection at a relatively low temperature is possible, but the connection reliability is lowered because the moisture resistance and the heat resistance of the resin are low. On the other hand, when the epoxy resin-based anisotropic conductive adhesive of the thermosetting type is used, since the connection time for curing the resin must be increased at low temperatures, practical application becomes difficult. That is, the anisotropically conductive adhesive resin currently commercialized does not satisfy all the balances of curability, workability, adhesiveness, connection reliability, and the like.

An object of the present invention is to provide a heat-curable anisotropic conductive adhesive useful for electrical connection of microcircuits, such as LCD and TCP connections, TCP and PCB connections, and the like.

Another object of the present invention is to provide an anisotropic conductive adhesive capable of connecting an electronic circuit at low temperature in a shorter time.

Still another object of the present invention is to provide an anisotropic conductive adhesive having excellent physical properties such as adhesiveness, connection reliability, storage stability, repair properties, and the like.

In order to achieve the above object, the present invention is a radically polymerizable resin; Organic peroxides; Thermoplastic elastomers; Urethane prepolymers; Reactive polymer resins; Electroconductive particle; And a particulate core / shell-type rubber, wherein the content of the organic peroxide is 1 to 10 parts by weight, and the content of the thermoplastic elastomer is 10 to 200 parts by weight, based on 100 parts by weight of the radically polymerizable resin. The content of the urethane prepolymer is 10 to 100 parts by weight, the content of the reactive polymer resin is 10 to 200 parts by weight, the content of the conductive particles is 1 to 30 parts by weight, and the content of the particulate core / shell-type rubber is 1 It provides to 30 parts by weight of the thermosetting anisotropic conductive adhesive.

The anisotropic conductive adhesive according to the present invention is particularly useful for the electrical connection between the glass substrate and the circuit board of the flat panel display, and the circuit board can be connected at a low temperature and short time with a heating temperature of 160 ° C. or less and a heating time of 5 seconds or less. In addition to excellent connection reliability and preservation, since it can be easily removed using a general organic solvent such as acetone, methyl ethyl ketone, etc., there is an advantage in that repairability is excellent.

Hereinafter, the present invention will be described in more detail.

MEANS TO SOLVE THE PROBLEM The present inventors, when a thermosetting anisotropic conductive adhesive is comprised by adding electroconductive particle and a particulate core / shell type rubber to the resin composition containing a radically polymerizable resin, an organic peroxide, a thermoplastic elastomer, a urethane prepolymer, and a reactive polymer resin, It has been found that the thermal stress of the anisotropic conductive adhesive is reduced, the warpage is small, and the adhesive strength is improved, which leads to the present invention. That is, the anisotropic conductive adhesive according to the present invention disperse conductive particles in a resin composition comprising a radical polymerizable resin, an organic peroxide, a thermoplastic elastomer, a urethane prepolymer, and a reactive polymer resin, and further, a particulate core / shell type rubber. It is characterized by the addition of.

The radically polymerizable resin used in the anisotropic conductive adhesive of the present invention is not particularly limited, but may be a compound or polymer capable of radical polymerization including one or more carbon-carbon double bonds in a molecule. Examples of the radically polymerizable resins include vinyl ester resins, unsaturated polyester resins, diallyl phthalate, acrylate resins, and the like, among others, curability, storage properties, heat resistance, moisture resistance, and resistance to hardened products. In consideration of chemical properties and the like, it is preferable to use a vinyl ester resin. Here, the vinyl ester resin may be obtained by the reaction of an epoxy resin and acrylic acid or methacrylic acid, or by the reaction of a glycidyl (meth) acrylate and a polyhydric phenol. The radically polymerizable resins may be used alone, but different structures, molecular weights and the like may be used in combination. It is preferable that the (weight average) molecular weight of the said radically polymerizable resin is 200-5,000 without limitation. In addition, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl acid phosphate, dimethyrol tricyclodecane dimethacryl, as necessary, in order to improve curability, fluidity at the time of heating, workability, and the like. Acrylate compounds, such as a latex, a propylene oxide modified bisphenol A diacrylate, a trimetholpropane triacrylate (TMPTA), a pentaerythritol diarylate monostearate, a tetraethylene glycol tea acrylate, and a pentaerythritol tetraacrylate Various radical monomers, such as styrene, and a general reactive diluent, etc. can also be used, diluting the said radically polymerizable resin.

Examples of the organic peroxide used in the present invention include, but are not limited to, dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, t-hexyl peroxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, t-butyl peroxy 2-ethylhexanoate, benzoyl peroxide, di (3-methylbenzoyl) peroxide, benzoyl (3-methylbenzoyl) peroxide, dibenzoyl peroxide, mixtures thereof and the like can be used. The said organic peroxide may be used independently, or may mix 2 or more types and control curability. In addition, various polymerization inhibitors may be added to the organic peroxide in advance to improve storage properties, or the organic peroxide may be diluted with a solvent or the like to facilitate the dissolution of the resin. The kind and compounding quantity of the said organic peroxide can be suitably selected in consideration of the balance of curability and storage property of an adhesive agent.

Although the thermoplastic elastomer contained in the resin composition of this invention is not specifically limited, Polyester resin, a polyurethane resin, a polyimide resin, polyvinyl acetate resin, nylon, a phenoxy resin, a polymethyl methacrylate resin, etc. Can be used, Preferably a phenoxy resin or a polyurethane resin can be used. The thermoplastic elastomers may be used alone or in combination of two or more in order to impart proper fluidity upon thermal compression. The molecular weight of the thermoplastic elastomer component may vary widely within the range of imparting fluidity and thermoplasticity to the adhesive, but is not limited to 5,000 to 1,000,000, more preferably 10,000 to 1,000,000, wherein the thermoplastic If the molecular weight of the stormer component is too small, the melt viscosity of the anisotropic conductive adhesive is low, and there is a fear that the adhesive component flows excessively when heated and pressed, and if too large, it is difficult to dissolve in the solvent and difficult to mix.

The urethane prepolymer used in the present invention is a copolymer of polyol and isocyanate, and the weight average molecular weight of the urethane prepolymer is preferably 500 to 100,000, more preferably 1,000 to 100,000, still more preferably 1,000 to 10,000. If the weight average molecular weight of the said urethane prepolymer is too low or high, there exists a possibility that the compatibility of a radically polymerizable resin and a thermoplastic elastomer may worsen. The urethane prepolymer may be used by purchasing a commercialized product such as a product of Songwon Industries, Japan Polyurethane Co., Ltd.

The reactive polymer resin used in the present invention is an acrylic ester copolymer, a resin obtained by copolymerizing two or more selected from ethyl acrylate, butyl acrylate and acrylonitrile, for example, ethyl acrylate / butyl acrylate / acrylic. Ronitrile copolymers, butyl acrylate / acrylonitrile copolymers, ethyl acrylate / acrylonitrile copolymers, and the like. In the reactive polymer resin, the content of ethyl acrylate, butyl acrylate and acrylonitrile is preferably 5 to 90% by weight, more preferably 10 to 80% by weight, respectively. The molecular weight of the reactive polymer resin is preferably, but not limited to, 50,000 to 1,000,000, more preferably 100,000 to 1,000,000. Here, when the molecular weight of the reactive polymer resin component is too small, the melt viscosity of the anisotropic conductive adhesive is low. When hot-pressing, there exists a possibility that an adhesive component may flow out excessively, and when too big | large, it may be difficult to melt | dissolve in a solvent, and mixing may become difficult.

The core / shell-type rubber particles used in the present invention are not particularly limited, but the core and the shell may be silicone-acrylic rubber, acrylic rubber, butadiene rubber, methacrylate butadiene styrene copolymer or the like. It may be used consisting of different components. In the core / shell-type rubber particles, the core is preferably made of butadiene rubber, and the shell is preferably made of acrylic rubber such as methyl methacrylate polymer. The size (diameter) of the core portion is about 100 nm to 1 μm, and the size (diameter) of the shell portion is about 150 nm to 1.5 μm. The core / shell-type rubber particles function to alleviate thermal stress due to heat and compression to increase adhesive strength, and are manufactured by Kaneka, Lock & Haas, Kureha Chemical, Soken Mitsubishi Rayon, Japan Xeon, BASF, Taiwan Plastic, LG Chemicals Commercialized products can be purchased and used.

As the electroconductive particle used for this invention, it is normally used for an anisotropic conductive adhesive, The particle | grains which have electroconductivity can be used without a restriction | limiting, For example, nickel, iron, copper, aluminum, tin, lead, chromium, cobalt. And metals coated on the surfaces of various metals such as silver and gold or metal alloys, metal oxides, carbon, glass, ceramics, and plastic particles. The particle diameter, material, compounding quantity, etc. of such electroconductive particle can be suitably selected and used according to the pitch, pattern, thickness of a circuit terminal, material, etc. of a circuit to be connected. In addition, the anisotropic conductive adhesive according to the present invention may contain an appropriate amount of coupling agent in order to modify the adhesiveness of the adhesive interface, to improve the adhesive strength, heat resistance, moisture resistance, connection reliability and the like as necessary. As said coupling agent, a zirconium series, titanium series, a silane coupling agent, etc. can be used, It is preferable to use a silane coupling agent especially. Specific examples of the coupling agent include epoxysilane-based, mercaptosilane-based and acrylicsilane-based coupling agents (e.g., β (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxy trimethoxysilane , γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and the like) can be exemplified. About the said electroconductive particle and a coupling agent, it is disclosed in detail in patent application publication 10-2005-0003841 of this inventor.

In the anisotropically conductive adhesive according to the present invention, the content of each component can be varied widely, as long as the physical properties of the anisotropic conductive adhesive are not impaired, but the preferred content is as follows. With respect to 100 parts by weight of the radically polymerizable resin, the preferred content of the organic peroxide is 1 to 10 parts by weight, the preferred content of the thermoplastic elastomer is 10 to 200 parts by weight, and the content of the urethane prepolymer is 10 to 100 parts by weight, the preferred content of the reactive polymer resin is 10 to 200 parts by weight, the preferred content of the conductive particles is 1 to 30 parts by weight, the preferred content of the particulate core / shell rubber is 1 to 30 parts by weight. . In addition, when the coupling agent is used, the content thereof is preferably 1 to 10 parts by weight based on 100 parts by weight of the radical polymerizable resin. Here, when the content of each component is out of the above range, there is a fear that the physical properties of the anisotropic conductive adhesive is lowered.

In the anisotropic conductive adhesive according to the present invention, after dissolving the above components in a solvent such as toluene, ethyl acetate, methyl ethyl ketone, and mixtures thereof, stirring and mixing, vacuum degassing as necessary, and then applied in a film form, solvent It can be prepared by removing the. It is preferable that the coating thickness of the anisotropic conductive adhesive containing electroconductive particle is generally 10-100 micrometers, and it is more preferable if it is 15-50 micrometers. The anisotropic conductive adhesive according to the present invention connects a flexible substrate of a flat panel display and an electrode of a glass substrate, mounts an electrode of a driving semiconductor chip or an electronic component on a flexible substrate, or mounts a driving semiconductor chip or an electronic component on a glass substrate. This is especially useful for direct access to. The anisotropic conductive adhesive according to the present invention has the advantage of being able to connect a circuit in a short time under low temperature conditions, and excellent in adhesiveness, connection reliability, storage stability, and repairability.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Examples 1 to 6 Preparation of Anisotropic Conductive Adhesive

As the radical polymerizable resin component, (i) 2-methacryloyloxyethyl acid phosphate (HS-100 manufactured by SK Cytec Co., Ltd. or Light Ester P2M manufactured by Kyoeisha Co., Ltd.), (ii) propylene Oxide modified bisphenol A diacrylate (Epoxy ester 3002A from Kyoeisha Co., Ltd., Ecryl 3708 from Daicel Cytec Co., Ltd.), (iii) Vinyl ester resin (Showa Polymer Co., Ltd.) Product epoxyy VR-60),

As the thermoplastic elastomer component, (i) phenoxy resin (Phenototo YP70 from Kukdo Chemical Co., Ltd., JER-4250 from Japan Epoxy, Japan), (ii) thermoplastic polyurethane (Unitika Japan) Eritel UE3500),

As a urethane prepolymer component, Niporan 3113 of Japan Polyurethanes,

As a reactive polymer resin component, Teisan Resin WS-023 from Nagase Chemtex, Japan, and Paraloid EXL-2655 from Rohm & Haas, USA were used as conductive particles and solvents (toluene and methylethyl). 1: 1 mixed solvent of a ketone (MEK), and it mixed in the content (unit: weight part) shown in following Table 1, and prepared the anisotropic conductive adhesive composition.

Example 1  Example 2 Example 3 Example 4 Example 5 Example 6 2-methacryloyloxyethyl acid phosphate 2 2 2 2 2 2 Propylene Oxide Modified Bisphenol A Diacrylate 10 10 10 10 10 10 Vinyl ester resin 15 15 15 15 15 15 Phenoxy resin 15 15 15 20 20 20 Polyurethane prepolymer 10 15 20 10 15 20 Thermoplastic polyurethane 15 15 15 10 10 10 Reactive polymer resin 25 20 15 25 20 15 Particle Core / Shell Rubber 3 3 3 3 3 3 Silane (Coupling Agent) One One One One One One Benzoyl peroxide 2 2 2 2 2 2 Conductive particles 2 2 2 2 2 2 toluene 50 50 50 50 50 50 Methyl ethyl ketone (MEK) 50 50 50 50 50 50

Adhesion Evaluation Sample Preparation : Indium / Tin oxide with copper foil / polyimide (thickness: 25/75 μm), TCP (pitch: 0.20 mm, number of terminals: 150) coated with 0.4 μm thick gold plating and 30 Ω sheet resistance An anisotropic conductive film (width 2mm) was placed between ITO glass of thickness 1.1mm which formed the film in the whole surface, and it heat-and-press-bonds on the conditions of temperature 160 degreeC, pressure 30kg / cm <^2> , 5 ^second , and an evaluation sample is Produced. About the produced evaluation sample, the initial adhesive force (adhesive strength) and connection resistance, the adhesive force (adhesive strength) after a reliability test, connection resistance, repair property, and storage stability were measured by the following method, and the result is shown in Table 2. Indicated.

(1) Adhesive force (adhesive strength) measurement : The adhesive strength (unit: N / cm) was measured using the tensile tester, peeling an evaluation sample at 50 mm / min of tensile speed and 90 degrees.

(2) Connection reliability test : An evaluation sample was subjected to 500 heat cycles at a temperature of -40 ° C to 100 ° C, left for 500 hours at 85 ° C and 85% humidity, and then measured for connection resistance and adhesion. It was.

(3) Evaluation of repair: the adhesive remaining on the glass sample to complete the bonding strength test was evaluated for control wipe repair property with a cotton swab moistened methylethyl ketonreul. When the residual adhesive was removed in 10 or less times, it was good, and when it was removed in 11-20 times, it was evaluated as bad when it was removed in 20 or more times.

(4) Storage Stability Evaluation : After 1 week, 2 weeks and 3 weeks of storage at room temperature away from direct sunlight, the TCP and glass substrates were bonded together, and the adhesion and connection resistance were evaluated. If it was good or more, it evaluated as bad.

Example 1  Example 2 Example 3 Example 4 Example 5 Example 6 Initial adhesion 11 12 10 12 13 11 Initial connection resistance 1.8 1.5 1.6 1.4 1.2 1.6 Adhesion after Reliability Test 9 9 8 8 9 8 After reliability test
Connection resistance 4 5 5 4 3 5 Repair Castle Good Good Good Good Good Good Storage stability Good Good Good Good Good Good

Comparative Examples 1 to 4 Preparation of Anisotropic Conductive Adhesive

Anisotropic conductive adhesive composition and adhesive evaluation sample were prepared in the same manner as in Example, except that each component was mixed in the content shown in Table 3 without using the particulate core / shell rubber component. In the same manner as described above, the initial adhesive force (adhesive strength) and the connection resistance, the adhesive force (adhesive strength) and the connection resistance, the repair property, and the storage stability after the reliability test were measured, and the results are shown in Table 4.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 2-methacryloyloxyethyl acid phosphate 2 2 2 2 Propylene Oxide Modification
Bisphenol A diacrylate 10 10 10 10 Vinyl ester resin 15 15 15 15 Phenoxy resin 0 0 40 40 Polyurethane prepolymer 10 15 10 15 Thermoplastic polyurethane 18 13 18 13 Reactive polymer resin 40 40 0 0 Particle Core / Shell Rubber - - - - Silane (Coupling Agent) One One One One Benzoyl peroxide 2 2 2 2 Conductive particles 2 2 2 2 toluene 50 50 50 50 Methyl ethyl ketone (MEK) 50 50 50 50

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Initial adhesion 10 11 9 9 Initial connection resistance 1.7 1.8 1.4 1.7 Adhesion after Reliability Test 8 9 5 4 Connection resistance after reliability test 5 4 12 15 Repair Castle Bad Bad Good Good Storage stability Good Good Good Good

From Tables 2 and 4 above, it can be seen that when the anisotropic conductive adhesive of the present invention containing the particulate core / shell rubber component is used, there is little change in the adhesive force and the connection resistance, and the repair property is excellent.

Claims (5)

Radically polymerizable resins; Organic peroxides; Thermoplastic elastomers; Urethane prepolymers; Reactive polymer resins; Electroconductive particle; And particulate core / shell type rubber, The content of the organic peroxide is 1 to 10 parts by weight, the content of the thermoplastic elastomer is 10 to 200 parts by weight, and the content of the urethane prepolymer is 10 to 100 parts by weight based on 100 parts by weight of the radical polymerizable resin. Part, the content of the reactive polymer resin is 10 to 200 parts by weight, the content of the conductive particles is 1 to 30 parts by weight, the content of the particulate core / shell-type rubber is 1 to 30 parts by weight, The urethane prepolymer is a copolymer of a polyol and an isocyanate, the weight average molecular weight is 500 to 10,000, In the particulate core / shell type rubber, the core portion has a size of 100 nm to 1 μm, and the shell portion has a size of 150 nm to 1.5 μm. The method of claim 1, wherein the radically polymerizable resin is a compound or polymer capable of being radically polymerized, including one or more carbon carbon double bonds in a molecule, and includes a vinyl ester resin, an unsaturated polyester resin, and a diaryl phthalate. , An acrylate resin and a mixture thereof. The method of claim 1, wherein the thermoplastic elastomer is selected from the group consisting of polyester resins, polyurethane resins, polyimide resins, polyvinyl acetate resins, nylons, phenoxy resins, polymethyl methacrylates, and mixtures thereof. Anisotropic conductive adhesive. The anisotropic conductive adhesive according to claim 1, wherein the reactive polymer resin is a resin obtained by copolymerizing two or more selected from the group consisting of ethyl acrylate, butyl acrylate and acrylonitrile. The anisotropic conductive adhesive according to claim 1, wherein the particulate core / shell-type rubber has a core of butadiene rubber and a shell of acrylic rubber.