JP2005336358A - Anisotropic electroconductive adhesive and heat seal connector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anisotropic electroconductive adhesive and heat seal connector that can be used for hours at normal temperature and is easy to handle. <P>SOLUTION: A pair of flexible insulating base materials 1, 1A are equipped and the electrode circuits 2, 2A are formed on the counter-face surface of the pair of the insulating base material and an anisotropic electroconductive adhesive 3 is placed between the pair of the electrode circuit and they are thermocompression bonded to form the adhesive layer 3A. The anisotropic electroconductive adhesive 3 is prepared from the microcapsules 32 that includes an epoxy resin 31 in each capsules, a hardening agent 33 for hardening the epoxy resin 31, a high molecule compound 34 having film-forming properties and electroconductive particles 35 and the average particle size of the microcapsules 32 is controlled in the range of from 20 to 100 μm and the wall film thickness of the capsules is set in the range of from 0.5 to 3.0 μm. Thereby the preserving properties can be sustained until the thermocompression bonding operation in no need of refrigeration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an anisotropic conductive adhesive and a heat seal connector for electrically connecting an electronic component such as an LCD (LCD panel) or a PDP and a circuit board having a drive circuit for the electronic component. .

In recent years, electronic devices are required to have higher functionality and higher performance, and therefore anisotropic conductive adhesives are used in many ways. In general, anisotropic conductive adhesives are generally made of insulating adhesives with conductive particles. It is prepared by containing (see Patent Documents 1 and 2).
As the insulating adhesive, an epoxy-based thermosetting resin that can obtain high connection reliability is mainly used. As the curing agent, a latent curing agent obtained by microencapsulating an imidazole-based or amine-based material is used in order to satisfy the need for short-time curing.
JP 2003-272440 A JP-A-10-219222

  However, although the latent curing agent is microencapsulated, since the solvent resistance of the capsule wall is low, there is a big problem that the pot life at normal temperature is short and it must be stored frozen. . In addition, there is also a problem that when forming into a film shape, it must be dried at a low temperature so that the curing reaction does not proceed.

  The present invention has been made in view of the above, and an object thereof is to provide an anisotropic conductive adhesive and a heat seal connector that can be used at room temperature for a long time and are easy to handle.

  As a result of repeated studies to solve the above problems, the present inventor separates the microcapsules encapsulating the epoxy resin and the curing agent, and adjusts the average particle diameter of the microcapsules and the film thickness of the wall, respectively. Thus, the present inventors have found that an anisotropic conductive adhesive having a stable storage property until thermocompression bonding and having excellent connection reliability after thermocompression bonding can be obtained.

That is, in order to solve the above-described problems, the present invention includes a microcapsule encapsulating an epoxy resin, a curing agent that cures the epoxy resin of the microcapsule, a polymer compound having film-forming properties, and conductive particles. The average particle size of the microcapsules is in the range of 20 to 100 μm, and the film thickness of the wall of the microcapsules is in the range of 0.5 to 3.0 μm.
In addition, the glass transition temperature of resin which forms the wall of a microcapsule can be made into the range of 60-150 degreeC.

  In the present invention, in order to solve the above-mentioned problem, a conductive layer is formed on a flexible base material, and the anisotropic conductive material according to claim 1 or 2 is formed in a connection region for an electric junction of the conductive layer. The adhesive layer is formed by applying a functional adhesive.

  Here, the electrical junction in the claims includes at least FPC, LCD, PDP, ITO, circuit board, glass substrate, glass such as a display panel, LSI chip, and the like. The connection region may be a part of the conductor layer or all of the conductor layer, and the connection region is not particularly limited.

  According to the present invention, since the average particle size of the microcapsules is in the range of 20 to 100 μm and the average particle size is 20 μm or more, high pressure is not required for mechanical destruction of the microcapsules, and with the destruction of the microcapsules. The electrical joint itself is less likely to be damaged. Further, since the average particle size is 100 μm or less, the microcapsules are not easily broken, and as a result, the performance of the anisotropic conductive adhesive is hardly impaired.

  In addition, since the film thickness of the microcapsule wall is in the range of 0.5 to 3.0 μm and the film thickness is 0.5 μm or more, the epoxy resin is eluted from the microcapsule and decreases the loss of storage stability. be able to. Further, since the film thickness is 30 μm or less, there is no difficulty in the destruction of the microcapsules, and the connection stability can be prevented from being lowered.

  Furthermore, since the glass transition temperature of the resin forming the wall of the microcapsule is in the range of 60 to 150 ° C., it is stable when stored at room temperature, and the wall is melted and destroyed during thermocompression bonding. The connection stability is improved.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that it can be used for a long time at normal temperature, and the anisotropic conductive adhesive and heat seal connector which are easy to handle can be provided.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. A heat seal connector according to the present embodiment includes a pair of upper and lower insulating base materials 1 and 1A having flexibility as shown in FIG. Electrode circuits 2 and 2A are respectively formed on the opposing surfaces of the pair of insulating bases 1 and 1A, and an anisotropic conductive adhesive 3 is interposed between the pair of electrode circuits 2 and 2A and thermocompression bonded. Thus, the adhesive layer 3A is formed.

  Each of the insulating bases 1 and 1A is formed into a thin rectangle using, for example, a thin polyester or polyimide resin film having excellent heat resistance and radiation resistance.

  The anisotropic conductive adhesive 3 includes a microcapsule 32 containing at least an epoxy resin 31, a curing agent 33 for curing the epoxy resin 31 of the microcapsule 32, a polymer compound 34 having film-forming properties, and conductive particles. 35.

  As the microcapsule 32 enclosing the epoxy resin 31, for example, an epoxy resin made of a liquid or solid bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, or the like is known. Encapsulated by the above. Known encapsulation methods include chemical methods represented by interfacial polymerization methods and in-situ polymerization methods, physicochemical methods such as coacervation methods and in-liquid drying methods, and mechanical methods such as mechanofusion and mechanochemicals. The method, spray drying method, impact method in high-speed air current, etc. are applicable.

  In addition to the above reaction, the microcapsule 32 has a predetermined particle size by strictly selecting and controlling the stirring speed, spray nozzle diameter, pressure, and the like of the reaction system. In addition, the wall of the microcapsule 32 has a concentration ratio and a compounding ratio between the epoxy resin 31 as a core material and the wall material, a concentration of the core material and the wall material with respect to the reaction material, or various reaction conditions (amount of catalyst, pH, temperature). , Time) is strictly selected and controlled to obtain a predetermined thickness.

  The average particle diameter of the microcapsules 32 is adjusted to a range of 20 to 100 μm. This is because, when the average particle size of the microcapsules 32 is less than 20 μm, the breaking strength of the microcapsules 32 is increased, so that the microcapsules 32 are not broken even when thermocompression bonded, and the curing of the epoxy resin 31 does not proceed. This is because the connection reliability decreases both electrically and mechanically. On the other hand, when the average particle size exceeds 100 μm, the microcapsule 32 is easily broken in the manufacturing process such as adjustment of the adhesive and printing, and the reaction with the curing agent 33 proceeds to impair storage stability. Because.

  Further, the film thickness of the wall of the microcapsule 32 is set in the range of 0.5 to 3.0 μm. This is because when the wall thickness is less than 0.5 μm, it affects the fluidity of the encapsulated epoxy resin 31, increases the aggregation between particles, and deteriorates the dispersibility of the particles. This is because even if the microcapsule 32 is broken, the epoxy resin 31 is cured in a non-uniform state and connection reliability is lowered.

  On the contrary, when the wall thickness is larger than 3.0 μm, the ratio of the wall material not involved in the bonding increases, so that the adhesiveness is lacking and the strength of the wall material becomes stronger than necessary, and the thermocompression bonding is performed. This is based on the reason that sometimes the microcapsule 32 is not easily broken and the connection reliability is lowered.

  The glass transition temperature of the resin forming the wall of the microcapsule 32 is set in the range of 60 to 150 ° C. As the wall resin, for example, polymethyl methacrylate (PMMA), polystyrene, polyamide, polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyethylene, polypropylene and the like are suitable. The wall of the microcapsule 32 may be a multilayer composite film having two, three or more layers of different materials.

  In addition, even if it is regarded as a thermosetting resin, it is possible to produce a resin having a glass transition temperature of 60 to 150 ° C. as a polymer having a linear structure without forming a three-dimensional network by devising synthesis conditions. Is known, such a resin may be used for the wall of the microcapsule 32.

  As the curing agent 33, an ordinary curing agent for epoxy resin is used. Examples thereof include amine compounds, imidazole compounds, phenol compounds, mercapto compounds, carboxylic acid compounds, hydroxyl group-containing compounds, isocyanates, and the like. In particular, amine compounds, imidazole compounds, and mercapto compounds having a high reaction rate are preferable. The curing agent 33 is mixed with various acids and amines as accelerators.

  These curing agents 33 can be microencapsulated in order to provide a potential if they are used for blending anisotropic conductive adhesives that are not particularly affected by solvents. For example, commercially available latent curing agents such as NovaCure (Asahi Kasei Epoxy Co., Ltd.), Amicure (Ajinomoto Fine Techno Co., Ltd.), FujiCure (Fuji Kasei Kogyo Co., Ltd.) and the like can be used.

This is effective because the anisotropic conductive adhesive 3 prevents moisture absorption by the curing agent 33 during storage and can sufficiently withstand high temperature storage conditions. However, care should be taken when selecting because there is a risk of delaying the curing time.
Further, even if there is some influence of the solvent, the pot life of the ink during film formation can be slightly improved, which is effective for manufacturing the anisotropic conductive adhesive 3 and the heat seal connector.

  The blending amount of the microcapsule 32 and the curing agent 33 is determined in consideration of the epoxy resin encapsulation rate of the microcapsule 32 and the epoxy equivalent of the epoxy resin 31. Usually, the non-polymerizable curing agent 33 such as an amine compound, a phenol compound, a carboxylic acid compound and the like excluding a tertiary amine is blended in an amount corresponding to the epoxy equivalent, and a catalytic curing agent such as an imidazole compound. 33 is blended slightly less than this.

  For example, about 20 to 60 parts by mass of DETA (diethylenetriamine) is blended in an epoxy resin having an epoxy equivalent of 184 to 194, but the epoxy encapsulating rate, for example, 90%, is applied to the value for the microencapsulated epoxy resin. What is necessary is just to mix | blend 18-54 mass parts.

  The polymer compound 34 is not particularly limited, but for example, ethylene-vinyl acetate copolymer, carboxyl-modified ethylene-vinyl acetate copolymer, ethylene-isobotyl acrylate copolymer, polyamide, polyester, polymethyl Methacrylate, polyvinyl ether, polyvinyl butyral, polyurethane, styrene-butadiene-styrene (SBS) copolymer, carboxyl-modified SBS copolymer, styrene-ethylene-butylene-styrene (SEBS) copolymer, maleic acid-modified SEBS copolymer , Polybutadiene rubber, chloroprene rubber (CR) carboxyl-modified CR, styrene-butadiene rubber, isobutylene-isoprene copolymer, acrylonitrile-butadiene rubber (NBR), carboxy-modified NBR, amine-modified NBR, Epoxy resins, phenoxy resins, phenol resins, silicone rubber, those obtained by one or a combination of two or more selected from acrylic rubber and the like.

  The conductive particles 35 include metal particles such as gold, silver, nickel, copper, palladium, stainless steel, brass, and solder, ceramic particles such as tungsten carbide and silica carbide, carbon particles, and plastic particles whose surfaces are coated with metal. Or a combination of these is used.

  The blending amount of the conductive particles 35 with respect to the insulating adhesive is 0.01 to 100 parts by volume, preferably 1 to 10 parts by volume with respect to 100 parts by volume of the insulating adhesive. This is because when the blending amount is less than 0.01 part by volume, conduction failure tends to occur, and conversely when the blending amount exceeds 100 volume parts, insulation failure tends to occur.

  In the anisotropic conductive adhesive 3 in this embodiment, rosin, rosin derivative, terpene resin, terpene phenol resin, petroleum resin, coumarone-indene resin, styrene resin, isoprene resin, alkylphenol resin, xylene are used as tackifiers. One or more resins such as a resin, a reactive aid, and the like are appropriately added. In addition, polyols, isocyanates, melamine resins, urea resins, utropine resins, amines, acid anhydrides, peroxides, metal oxides, trifluoroacetic acid chromium salts and other organic metal salts such as titanium, zirconia, Alkoxides such as aluminum, organometallic oxides such as dibutyltin dioxide, photoinitiators such as 2.2-diethoxyacetonephenone and benzyl, and sensitizers such as amines, phosphorus compounds and chlorine compounds are appropriately added. . Further, a curing agent, a vulcanizing agent, a deterioration preventing agent, a heat resistance additive, a heat conduction improver, a softening agent, a colorant, various coupling agents, a metal deactivator, and the like are selectively added.

  According to the above, since the average particle diameter of the microcapsule 32 and the film thickness of the wall are adjusted, and the microcapsule 32 is separated from the curing agent 33, stable storage properties are maintained until thermocompression bonding without being stored frozen. Can be obtained. Moreover, the anisotropic conductive adhesive 3 excellent in connection reliability can be obtained after thermocompression bonding.

  Next, FIG. 2 shows a second embodiment of the present invention. In this case, a flexible insulating base material 1 is provided, and a plurality of insulating base materials 1 are provided in the longitudinal direction of the surface of the insulating base material 1. The conductive patterns 4 are arranged in parallel at a predetermined interval, and the insulating resist layer 6 is laminated on the non-connection portions 5 of the plurality of conductive patterns 4, and the connection portions 7 of the plurality of conductive patterns 4 are arranged. In other words, the anisotropic conductive adhesive 3 is applied to both ends so as to form the adhesive layer 3A for the electrical junction 8.

  As the plurality of conductive patterns 4, a screen-printed conductive paste in which a conductive imparting agent such as silver powder, copper powder, carbon black, and graphite having a particle size of about 0.01 to 10 μm is mixed with an organic binder, Examples thereof include a pattern obtained by etching a metal foil. Of course, other conductive patterns can be used. The height of each conductive pattern 4 is about 1 to 50 μm, and the finer the conductive pattern 4 is, the easier the manufacture of the lower conductive pattern 4 is.

  The insulating resist layer 6 is made of polyamide, polyester, polyimide, polyurethane, acrylic, or other synthetic resin, various synthetic rubbers, or a mixture thereof, and includes addition of a curing agent, a vulcanizing agent, a deterioration preventing agent, etc. A material was added as necessary and dissolved in a solvent, and a screen-printed layer, a film such as polyimide, polyester, and vinyl chloride was coated with an adhesive such as an acrylic resin or an adhesive such as an epoxy resin, and adhered. Things can be raised.

Examples of the electrical joint 8 include glass such as a display panel. The other parts are the same as those in the above embodiment, and the description thereof is omitted.
In this embodiment, it is obvious that the same effect as the above embodiment can be expected.

  Examples of the anisotropic conductive adhesive and heat seal connector according to the present invention will be described below together with comparative examples.

Example (1) Preparation of Insulating Adhesive Solution Phenoxy resin [trade name PKHH, manufactured by Inchem] 100 parts by mass, modified amine-based curing agent [trade name Epomate RX221, manufactured by JER] 35 parts by weight, liquid in an epoxy equivalent of 184 to 194 To 100 parts by mass of microcapsules encapsulating bisphenol A type epoxy resin (trade name Epicoat 828, manufactured by Japan Epoxy Resin Co., Ltd.) with a urea resin / melamine resin / formaldehyde mixture, 300 parts by mass of MEK: toluene = 3: 7 solvent is added to insulate. An adhesive solution was prepared.

  The microcapsules were of a type having an average particle size of 44 μm, a wall film thickness of 1.1 μm, and a wall film glass transition temperature of 110 ° C.

(2) Preparation of anisotropic conductive adhesive To 100 parts by mass of the solid content of the insulating adhesive solution, 10 parts by mass of conductive particles made of nickel particles whose surface is Au-plated are added, and the anisotropic conductive adhesive is added. Prepared. The nickel particles had an average particle size of 6 μm.

(3) Production of heat seal connector An FPC having a circuit pattern of 0.2 mm pitch (pattern / space = 0.1 mm / 0.1 mm) is formed on a polyimide film having a thickness of 25 μm, and this FPC is not connected. In addition, an insulating resist layer was laminated and an anisotropic conductive adhesive was screen-printed on the connecting portion of the FPC to form an adhesive layer, and this intermediate was cut to a predetermined size to produce a heat seal connector. The circuit pattern was formed of a copper foil having a thickness of 18 μm. The anisotropic conductive adhesive was screen-printed so that the average thickness of the portion excluding the microcapsules after removing the solvent was 20 μm.

Comparative Example 1
(1) Preparation of Insulating Adhesive Solution Phenoxy resin [trade name PKHH manufactured by Inchem] 100 parts by mass, modified amine-based curing agent [trade name Epomate RX221 manufactured by JER] 35 parts by weight, liquid bisphenol A having an epoxy equivalent of 184 to 194 To 120 parts by mass of microcapsules encapsulating type epoxy resin [trade name Epicoat 828 made by Japan Epoxy Resin] with polymethyl methacrylate (PMMA), 300 parts by mass of MEK: toluene = 3: 7 solvent is added, and the insulating adhesive solution is added. Prepared.

  The microcapsules were of the type having an average particle size of 15 μm, a wall film thickness of 0.6 μm, and a wall film glass transition temperature of 105 ° C. (2) Preparation of anisotropic conductive adhesive and (3) Heat seal connector production were the same as in the examples.

Comparative Example 2
(1) Preparation of Insulating Adhesive Solution Phenoxy resin [trade name PKHH manufactured by Inchem] 100 parts by mass, modified amine-based curing agent [trade name Epomate RX221 manufactured by JER] 35 parts by weight, liquid bisphenol A having an epoxy equivalent of 184 to 194 To 120 parts by mass of microcapsules encapsulating type epoxy resin [trade name Epicoat 828 made by Japan Epoxy Resin] with polymethyl methacrylate (PMMA), 300 parts by mass of MEK: toluene = 3: 7 solvent is added, and the insulating adhesive solution is added. Prepared.

  The microcapsules were of the type having an average particle size of 37 μm, a wall film thickness of 0.1 μm, and a wall film glass transition temperature of 103 ° C. (2) Preparation of anisotropic conductive adhesive and (3) Heat seal connector production were the same as in the examples.

Comparative Example 3
(1) Preparation of Insulating Adhesive Solution Liquid bisphenol A having 100 parts by mass of phenoxy resin [trade name PKHH manufactured by Inchem], 35 parts by weight of a modified amine-based curing agent [trade name Epomate RX221 manufactured by JER], and epoxy equivalents 184 to 194 Type epoxy resin [trade name Epicoat 828 made by Japan Epoxy Resin] with 60 parts by mass of microcapsules encapsulated in a urea resin / melamine resin / formaldehyde mixture, 300 parts by mass of MEK: toluene = 3: 7 solvent, and an insulating adhesive A solution was prepared.

  The microcapsules were of the type having an average particle size of 120 μm, a wall film thickness of 1.6 μm, and a wall film glass transition temperature of 112 ° C. (2) Preparation of anisotropic conductive adhesive and (3) Heat seal connector production were the same as in the examples.

Comparative Example 4
(1) Preparation of Insulating Adhesive Solution Phenoxy resin [trade name PKHH manufactured by Inchem] 100 parts by mass, modified amine-based curing agent [trade name Epomate RX221 manufactured by JER] 35 parts by weight, liquid bisphenol A having an epoxy equivalent of 184 to 194 Type epoxy resin [trade name Epicoat 828 made by Japan Epoxy Resin] with 60 parts by mass of microcapsules encapsulated in a urea resin / melamine resin / formaldehyde mixture, 300 parts by mass of MEK: toluene = 3: 7 solvent, and an insulating adhesive A solution was prepared.

  The microcapsules were of the type having an average particle size of 40 μm, a wall film thickness of 3.2 μm, and a wall film glass transition temperature of 110 ° C. (2) Preparation of anisotropic conductive adhesive and (3) Heat seal connector production were the same as in the examples.

Storage test The heat seal connectors of Examples and Comparative Examples 1 to 4 were stored in a constant temperature bath at 40 ° C. for January and March, respectively, and each heat seal connector was a transparent conductive oxide film substrate (ITO) with an area resistivity of 50Ω / □. And PCB were thermocompression bonded under conditions of 180 ° C., 4 MPa, 20 seconds, and then the peel strength from ITO and the resistance value change before and after the reliability test (85 ° C., 85% RH, 500 hours) (500 Resistance values after time-initial resistance values) were measured and summarized in Tables 1 and 2.

It is a schematic cross section explanatory view showing an embodiment of an anisotropic conductive adhesive and a heat seal connector concerning the present invention. It is a schematic cross-section explanatory drawing which shows 2nd Embodiment of the anisotropically conductive adhesive which concerns on this invention, and a heat seal connector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation base material 1A Insulation base material 2 Electrode circuit (conductor layer, connection area)
2A electrode circuit (conductor layer, connection area)
3 Anisotropic conductive adhesive 3A Adhesive layer 4 Conductive pattern (conductor layer)
5 Non-connection part 6 Insulating resist layer 7 Connection part (connection area)
8 Electrical Joint 31 Epoxy Resin 32 Microcapsule 33 Curing Agent 34 Polymer Compound 35 Conductive Particles

Claims (3)

A microcapsule encapsulating an epoxy resin, a curing agent for curing the epoxy resin of the microcapsule, a polymer compound having film-forming properties, and conductive particles,
An anisotropic conductive adhesive, characterized in that the average particle size of the microcapsules is in the range of 20 to 100 μm, and the thickness of the wall of the microcapsules is in the range of 0.5 to 3.0 μm.   The anisotropic conductive adhesive according to claim 1, wherein the glass transition temperature of the resin forming the wall of the microcapsule is in the range of 60 to 150 ° C.   A conductive layer is formed on a flexible base material, and the anisotropic conductive adhesive according to claim 1 or 2 is applied to a connection region for an electrical junction of the conductive layer to form an adhesive layer. Heat seal connector characterized by.

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