JP2008111092A - Circuit-connecting material and connection structure using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit-connecting material able to maintain high adhesive strength under high temperature and high humidity even when used for mounting COF (chip on film) and, at the same time, exhibits excellent connection reliability and preservation stability. <P>SOLUTION: The circuit-connecting material 1 comprises (1) an epoxy resin, (2) a latent curing agent and (3) a compound having an epoxy group and an acrylate group and is used for electrically connecting mutually facing circuit electrodes to each other. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a circuit connection material and a connection structure using the same.

  In manufacturing a semiconductor element or a liquid crystal display element, a circuit connection material such as an anisotropic conductive adhesive is used to connect circuit members to each other. In mounting a semiconductor silicon chip on a substrate, instead of the conventional wire bonding sheet, in recent years, so-called flip chip mounting in which the semiconductor silicon chip is directly mounted on the substrate has been performed. Circuit connection materials such as are applied.

  As a circuit connection material, a thermosetting resin composition using an epoxy resin having high adhesiveness and high reliability has been used (for example, see Patent Document 1). A thermosetting resin composition using an epoxy resin is generally composed of components such as an epoxy resin and a curing agent such as a phenol resin that reacts with the epoxy resin. In order to ensure the storage stability of the circuit connecting material at room temperature, a latent curing agent is usually used as a curing agent. The latent curing agent is an important factor for determining the curing temperature and the curing rate, and various compounds have been studied as latent curing agents from the viewpoint of storage stability at room temperature and curing rate during heating.

  Recently, attention has been focused on the use of radical curable adhesives as circuit connection materials in which acrylate derivatives or methacrylate derivatives are combined with peroxides as radical polymerization initiators. In the case of radical curable adhesives, radicals that are reactive species are highly reactive and can be cured in a short time (see, for example, Patent Documents 2 and 3).

  By the way, in the connection between the liquid crystal display and TCP (Tape Carrier Package) or COF (Chip On Flex), the connection between FPC (Flexible Printed Circuit) and TCP, and the connection between FPC and PWB (Printed Wiring Board), A circuit connection material such as an anisotropic conductive adhesive in which conductive particles are dispersed is used.

In particular, as a method of mounting a driver IC on a liquid crystal display, a method of mounting a COF is becoming mainstream.
Japanese Patent Laid-Open No. 1-113480 JP 2002-203427 A International Publication No. 98/044067 Pamphlet

  However, when COF is connected to other circuit members using a conventional circuit connecting material, there is a problem that the adhesive strength after high-temperature and high-humidity treatment tends to be lower than in the case of TCP. The reason for this is that the constituent materials differ between COF and TCP. In general, TCP has a three-layer configuration of “copper foil-adhesive layer-polyimide film”, whereas COF has a two-layer configuration of “copper foil-polyimide film”. That is, in the case of TCP, the adhesive layer is exposed between adjacent circuit electrodes, and the high adhesive strength between the adhesive and the circuit connecting material makes it easy to maintain high adhesive strength after high-temperature processing. On the other hand, in the case of COF, a polyimide film is exposed between adjacent circuit electrodes. It is considered that the adhesive strength between the polyimide film and the conventional circuit connecting material is relatively low, so that the decrease in the adhesive strength after the high temperature and high humidity treatment is increased.

  Accordingly, the present inventors have studied methods for maintaining high adhesive strength after high-temperature and high-humidity processing in the case of COF mounting, and have found some methods that are effective to some extent. However, both methods have a problem that other characteristics such as connection reliability and storage stability are extremely deteriorated.

  The present invention has been made in view of the above circumstances, and can maintain high adhesive strength under high temperature and high humidity even when used for mounting COF, and at the same time, excellent An object of the present invention is to provide a circuit connection material that exhibits connection reliability and storage stability.

  As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention extremely reduce connection reliability and storage stability by using a compound having one or more epoxy groups and acrylate groups in combination with an epoxy resin. And found that the adhesive strength after the high-temperature and high-humidity treatment can be improved, and the present invention has been completed.

  That is, the circuit connection material according to the present invention contains (1) an epoxy resin, (2) a latent curing agent, and (3) a compound having an epoxy group and an acrylate group. This circuit connection material is used to electrically connect the opposing circuit electrodes.

  According to the circuit connecting material according to the present invention, it is possible to maintain high adhesive strength under high temperature and high humidity even when used for mounting COF, and at the same time, excellent connection reliability. And storage stability is obtained.

  In another aspect, the invention relates to a connection structure. The connection structure according to the present invention is formed on the first substrate and the first circuit member having the first circuit electrode formed on the main surface thereof, and on the second substrate and the main surface thereof. The second circuit electrode is disposed so that the second circuit electrode and the first circuit electrode face each other, and the second circuit electrode is electrically connected to the first circuit electrode. A second circuit member, and a connection portion interposed between the first circuit member and the second circuit member. The connection portion is a cured product of the circuit connection material according to the present invention.

  The connection structure according to the present invention can maintain high adhesive strength under high temperature and high humidity even when the first circuit member or the second circuit member is COF, and at the same time, excellent Connection reliability and storage stability.

  According to the circuit connection material according to the present invention, it is possible to maintain high adhesive strength under high temperature and high humidity even when used for mounting COF, and at the same time, excellent connection reliability and It is possible to develop storage stability.

  The circuit connection material according to the present embodiment is an adhesive used to electrically connect circuit electrodes. FIG. 1 is a cross-sectional view showing an embodiment of a circuit connecting material. A circuit connecting material 1 shown in FIG. 1 is composed of an adhesive layer 3 and a plurality of conductive particles 5 dispersed in the adhesive layer 3 and has a film shape. The adhesive layer 3 contains an epoxy resin, a latent curing agent, and a compound having an epoxy group and an acrylate group. In other words, the circuit connection material 1 contains an epoxy resin, a latent curing agent, a compound having an epoxy group and an acrylate group, and conductive particles 5. When the circuit connection material 1 is heated, a crosslinked structure is formed in the adhesive layer 3 by crosslinking of the epoxy resin, and a cured product of the circuit connection material 1 is formed.

  As the epoxy resin, any epoxy compound having two or more epoxy groups and having no acrylate group can be used without particular limitation. Typical epoxy resins are bisphenol type epoxy resins which are glycidyl ethers of bisphenols such as bisphenol A, F and D, and epoxy novolac resins derived from phenol novolac or cresol novolac. Other examples include glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins. These are used individually or in mixture of 2 or more types.

  Among the above epoxy resins, bisphenol type epoxy resins are preferable because grades with different molecular weights are widely available, and adhesiveness, reactivity, and the like can be arbitrarily set. Among bisphenol type epoxy resins, bisphenol F type epoxy resins are particularly preferable. The viscosity of the bisphenol F type epoxy resin is low, and the fluidity of the circuit connecting material can be easily set in a wide range by using it in combination with the phenoxy resin. Further, the bisphenol F type epoxy resin has an advantage that it is easy to impart good adhesiveness to the circuit connecting material.

  A so-called polyfunctional epoxy resin having three or more epoxy groups is also preferred because the crosslink density of the cured product is increased and its heat resistance is improved. However, since the repair with a solvent tends to be difficult when the amount of the polyfunctional epoxy resin is increased, the ratio of the polyfunctional epoxy resin in the adhesive layer 3 is preferably 30% by mass or less.

It is preferable to use an epoxy resin having an impurity ion (Na ⁺ , Cl ⁻ etc.) concentration or hydrolyzable chlorine of 300 ppm or less to prevent electron migration.

  The latent curing agent used for the circuit connection material 1 may be a compound that reacts with the epoxy resin and is incorporated into the crosslinked structure, or may be a catalytic curing agent that accelerates the curing reaction of the epoxy resin. . Both can be used in combination.

  Examples of the catalytic curing agent include an anionic polymerization latent curing agent that promotes anionic polymerization of an epoxy resin and a cationic polymerization latent curing agent that promotes cationic polymerization of an epoxy resin. In particular, an anionic polymerization type latent curing agent is preferable because it can exhibit strong adhesive strength to various adherends.

  Examples of the anionic polymerization type latent curing agent include imidazole series, hydrazide series, trifluoroboron-amine complex, amine imide, polyamine salt, dicyandiamide, and modified products thereof. These can be used alone or as a mixture of two or more. The imidazole-based anionic polymerization latent curing agent is formed, for example, by adding imidazole or a derivative thereof to an epoxy resin.

  The compounding amount of the anionic polymerization type latent curing agent is preferably 20 to 50 parts by weight, and more preferably 30 to 40 parts by weight with respect to 100 parts by weight of the epoxy resin. If it is less than 20 parts by weight, the clamping force on the adherend due to the curing shrinkage of the circuit connecting material is reduced. As a result, the contact between the conductive particles 5 and the circuit electrode is not maintained, and the connection resistance after the reliability test tends to increase. If it exceeds 60 parts by weight, the tightening force becomes too strong, so that the internal stress in the cured product of the circuit connecting material tends to increase, and the adhesive strength tends to decrease.

  The adhesive layer 3 contains one or more compounds having an epoxy group and an acrylate group. The reason why the adhesive strength after high-temperature and high-humidity treatment can be maintained high by using a compound having an epoxy group and an acrylate group is presumed as follows. This compound is taken into the crosslinked structure by the reaction of the epoxy group during the curing of the circuit connecting material. When moisture penetrates into the circuit connection material after curing, the acrylate group of the crosslinked structure is hydrolyzed to newly generate a hydroxyl group. This hydroxyl group is considered to contribute to the improvement of the adhesive strength after the high temperature and high humidity treatment. However, this action mechanism is not yet clear, and the present invention is not limited to the one having such an action function.

  The compound having an epoxy group and an acrylate group is preferably a compound having a functional group that reacts with an epoxy group (for example, a carboxyl group) and an acrylate group with respect to a part of the epoxy group of the epoxy resin having two or more epoxy groups. Is a compound obtained by adding The epoxy resin used in this case is preferably a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol novolac resin, or a cresol novolac resin from the viewpoint of maintaining physical properties after curing. The compound having a functional group that reacts with an epoxy group and an acrylate group is typically acrylic acid having a carboxyl group and an acrylate group. For example, a compound obtained by adding acrylic acid to one epoxy group of a bisphenol A type epoxy resin has a structure represented by the following chemical formula. A compound represented by the following chemical formula is commercially available as “EA-1010N” (manufactured by Shin-Nakamura Chemical Co., Ltd.).

  The compound having an epoxy group and an acrylate group preferably has a weight average molecular weight of 200 to 60,000, more preferably 400 to 10,000. When the weight average molecular weight is less than 200, the physical properties after curing are likely to be lowered, and when it exceeds 60000, the flow of the circuit connecting material at the time of curing is hindered and the connection resistance tends to increase.

  The compounding amount of the compound having an epoxy group and an acrylate group is preferably 10 to 40 parts by weight, more preferably 20 to 30 parts by weight with respect to 100 parts by weight of the total amount of the epoxy resin and the latent curing agent. preferable. If it is less than 10 parts by weight, the effect of maintaining the adhesive strength after high-temperature and high-humidity treatment tends to be small, and if it exceeds 40 parts by weight, the physical properties of the adhesive after curing are lowered, and the connection reliability is likely to be lowered. Tend to be.

  The circuit connection material 1 (adhesive layer 3) may contain a thermoplastic resin. Examples of the thermoplastic resin include polyvinyl butyral resin, polyvinyl formal resin, polyamide resin, polyester resin, phenol resin, phenoxy resin, polystyrene resin, xylene resin, and polyurethane resin. Among these, a phenoxy resin is particularly preferable from the viewpoints of film formability and adhesiveness.

The thermoplastic resin preferably has a weight average molecular weight of 10,000 or more from the viewpoint of film forming properties. However, when the weight average molecular weight of the thermoplastic resin is 1000000 or more, mixing with other components tends to be difficult. In addition, the weight average molecular weight prescribed | regulated by this application means the value determined based on the calibration curve by a standard polystyrene by the gel permeation chromatography method (GPC) of the following conditions.
Equipment using GPC conditions: Hitachi L-6000 type (Hitachi, Ltd.)
Column: Gel pack GL-R420 + Gel pack GL-R430 + Gel pack GL-R440 (3 in total) (trade name, manufactured by Hitachi Chemical Co., Ltd.)
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 ml / min
Detector: L-3300RI (Hitachi, Ltd.)

  The thermoplastic resin preferably has a hydroxyl group. The thermoplastic resin preferably has a Tg (glass transition temperature) of 40 ° C. or higher. From this point of view, the phenoxy resin can be preferably used. The phenoxy resin is obtained, for example, by a method of polymerizing a bifunctional phenol and epihalohydrin to polymerize or a method of polyaddition reaction of a bifunctional epoxy resin and a bifunctional phenol.

  The resin having a hydroxyl group may be modified with an epoxy group-containing elastomer or may have a radical polymerizable functional group. When a material having a radical polymerizable functional group is used, the heat resistance of the cured product of the circuit connection material can be further improved.

  The circuit connection material 1 (adhesive layer 3) may contain an elastomer having an epoxy group. Epoxy groups are present at the molecular ends or molecular chains of the elastomer. Examples of the elastomer having an epoxy group include a butadiene polymer containing butadiene as a monomer unit, an acrylic polymer (acrylic rubber), a polyether urethane rubber, a polyester urethane rubber, a polyamide urethane rubber, and a silicone rubber. Of these, butadiene polymers and acrylic polymers are preferred. Examples of the butadiene polymer include a butadiene polymer, a butadiene-styrene copolymer, and a butadiene-acrylonitrile copolymer. Of these, butadiene-acrylonitrile copolymers are particularly preferred.

  The circuit connection material 1 (adhesive layer 3) may contain other components in addition to the above components. For example, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents, phenol resins, melamine resins, and isocyanates can be used as other components. The coupling agent is preferably a compound having a vinyl group, an epoxy group, an acrylic group, an amino group, or an isocyanate group other than the above-described components from the viewpoint of improving adhesiveness.

  Examples of the conductive particles 5 include metal particles including metals such as Au, Ag, Ni, Cu and solder, and carbon particles. The conductive particles 5 are preferably composed of a metal selected from Au, Ag and a platinum group noble metal, more preferably Au. Since the outermost layer of the conductive particles 5 is composed of these metals, the storage stability of the circuit connection material 1 is further enhanced. The conductive particles 5 may be coated particles having a core composed of a transition metal such as Ni and the outermost layer that covers the surface of the core. Alternatively, it may be a coated particle having an insulating core composed of glass, ceramic or plastic and the outermost layer covering the surface of the core. In particular, coated particles having a core composed of a plastic or a hot-melt metal are preferable. Such coated particles are deformed when the circuit connecting material 1 is heated and pressurized. As a result, the contact area between the conductive particles 5 and the circuit electrode is increased, and the connection reliability is improved.

  Although the compounding quantity of the electroconductive particle 5 is suitably set with a use, it is 0.1-30 with respect to 100 volume parts of adhesive bond layers 3 (namely, parts other than the electroconductive particle 5 among the circuit connection materials 1) normally. Within the volume range. Furthermore, from the viewpoint of preventing short circuit between adjacent circuit electrodes on the same circuit board, the blending amount of the conductive particles is more preferably 0.1 to 10 parts by volume.

  The circuit connection material according to the present invention is not limited to the configuration shown in FIG. For example, the circuit connection material may have a laminated structure composed of two or more layers having different compositions. In this case, for example, the curing agent and the conductive particles may be included in separate layers. This further improves the storage stability (pot life) of the circuit connecting material. The circuit connecting material may not contain conductive particles.

  The circuit connection material according to the present embodiment includes, for example, chip components such as a semiconductor chip, a resistor chip and a capacitor chip, and circuit members having one or more circuit electrodes (connection terminals) such as a printed wiring board. Is preferably used to form a connection structure in which are connected.

  FIG. 2 is a cross-sectional view showing an embodiment of a connection structure. The connection structure 100 shown in FIG. 2 includes a first circuit member 10 having a first substrate 11 and a first circuit electrode 13 formed on the main surface of the first substrate 11, a second substrate 21, and a main body thereof. A second circuit member 20 having a second circuit electrode 23 formed on the surface and disposed so that the second circuit electrode 23 and the first circuit electrode 13 face each other; And a connecting portion 1a interposed between the member 10 and the second circuit member 20. Opposing first circuit electrode 13 and second circuit electrode 23 are electrically connected.

  The connection part 1a is a cured product formed by curing the circuit connection material 1. The connection portion 1a bonds the first circuit member 10 and the second circuit member 20 so that the first circuit electrode 13 and the second circuit electrode 23 facing each other are electrically connected. . The opposing first circuit electrode 13 and second circuit electrode 23 are electrically connected via the conductive particles 5. In addition, when the connection part does not contain conductive particles, the first circuit electrode 13 and the second circuit electrode 23 are in direct contact with each other, so that electrical connection is possible.

  The first substrate 11 is a resin film containing at least one resin selected from the group consisting of polyester terephthalate, polyethersulfone, epoxy resin, acrylic resin, and polyimide resin. The first circuit electrode 13 is formed from a material having conductivity that can function as an electrode (preferably at least one selected from the group consisting of gold, silver, tin, platinum group metals, and indium-tin oxide). Has been.

  The second substrate 21 is a glass substrate. The second circuit electrode is preferably formed from a transparent conductive material. Typically, ITO is used as the transparent conductive material.

  In the case where the connection portion 1a is in direct contact with a substrate formed of a material such as polyester terephthalate, polyethersulfone, epoxy resin, acrylic resin, or polyimide resin, as in the connection structure 100, a conventional circuit connection material However, it was difficult to maintain high adhesive strength after high-temperature and high-humidity treatment. On the other hand, in the connection structure 100, since the connection part 1a is the hardened | cured material of the circuit connection material 1, sufficiently high adhesive strength can be maintained also in a high temperature, high humidity environment. Such an effect is also obtained when a surface layer containing a polyimide resin, an acrylic resin, a silicone resin, or the like is formed between the connection portion and the circuit member.

  The circuit member connection structure 100 includes, for example, the first circuit member 10, the above-described film-like circuit connection material 1, and the second circuit member 20, and the first circuit electrode 13 and the second circuit. The first circuit member is configured so that the first circuit electrode 13 and the second circuit electrode 23 are electrically connected by heating and pressurizing the laminate laminated in this order so as to face the electrode 23. 10 and the second circuit member 20 are obtained.

  In this method, first, the circuit-connecting material 1 formed on the support film is temporarily bonded to the second circuit member 20 by heating and pressurizing the circuit-connecting material 1 while being bonded together, After peeling off the support film, the first circuit member 10 can be placed while aligning the circuit electrodes to prepare a laminate. In order to prevent the influence on the connection due to the volatile components generated by the heating at the time of connection, it is preferable to heat-treat the circuit member in advance before the connection step.

Conditions for heating and pressurizing the laminate are appropriately adjusted so that the circuit connecting material is cured and sufficient adhesive strength is obtained in accordance with the curability of the adhesive composition in the circuit connecting material.

  The present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof. For example, in order to obtain a better electrical connection, at least one of the circuit electrodes (connection terminals) has an outermost layer composed of at least one metal selected from gold, silver, tin, and a platinum group. Is preferred. The circuit electrode may have a multilayer structure in which a plurality of metals are combined such as copper / nickel / gold.

  The substrate included in the circuit member constituting the connection structure may be a semiconductor chip such as silicon and gallium / arsenic, and an insulating substrate such as glass, ceramics, glass / epoxy composite, and plastic.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Production of circuit connection material Raw material “HX-3941HP”: Mixture of epoxy resin and imidazole microcapsule type curing agent which is an anionic polymerization type latent curing agent (manufactured by Asahi Kasei Chemicals Corporation)
“EA-1010N”: Compound having one epoxy group and one acrylate group (manufactured by Shin-Nakamura Chemical Co., Ltd.)
“PKHC”: film-forming component (phenoxy resin, weight average molecular weight 45000, manufactured by Inchem Corporation)
"Acrylic rubber 1": copolymer of 40 parts by weight of butyl acrylate-30 parts by weight of ethyl acrylate-30 parts by weight of acrylonitrile-3 parts by weight of glycidyl methacrylate (weight average molecular weight of about 850,000)
"Acrylic rubber 2": 5 parts by weight of butyl acrylate-73.5 parts by weight of ethyl acrylate-20 parts by weight of acrylonitrile-2 parts by weight of hexylmethyl acrylate-2 parts by weight of acrylic acid (weight average molecular weight 500,000)
"Ethylene-vinyl acetate copolymer" (vinyl acetate content 41%, melt flow rate 65 g / min according to JIS K 6730)
“Conductive coated particles”: Conductive particles “SH6040” having a 0.1 μm Ni layer and an Au layer on the surface of polystyrene spherical particles having an average particle diameter of 4 μm: Silane coupling agent (γ-glycidoxypropyltri Methoxysilane, Toray Dow Corning Silicone Co., Ltd.)

Example 1
45 parts by weight of HX-3941HP, 10 parts by weight of EA-1010N, and 37.5 parts by weight of a 40% by mass phenoxy resin solution obtained by dissolving PKHC in a mixed solvent of toluene / ethyl acetate = 50/50 (phenoxy 15 parts by weight of resin), 300 parts by weight of a solution of 10% by weight of acrylic rubber 1 obtained by dissolving acrylic rubber 1 in a mixed solvent of toluene / ethyl acetate = 50/50 (30 parts by weight as acrylic rubber 1) 4 parts by weight of conductive coated particles and 1 part by weight of SH6040 were blended to obtain a mixed solution. The obtained mixed solution was applied onto a PET film with an applicator, and the solvent was removed by hot air drying at 70 ° C. for 10 minutes to obtain a film-like circuit connection material having a thickness of 20 μm formed on the PET film. .

Example 2
45 parts by weight of HX-3941HP, 15 parts by weight of EA-1010N, 37.5 parts by weight of phenoxy resin solution (15 parts by weight as phenoxy resin), 250 parts by weight of solution of acrylic rubber 1 (25 parts by weight as acrylic rubber 1) Part), conductive coating particles are 4 parts by weight, SH6040 is 1 part by weight, except that the amount of each component was changed in the same manner as in Example 1 to obtain a film-like circuit connection material It was.

Comparative Example 1
50 parts by weight of HX-3941HP, 350 parts by weight of acrylic rubber 1 solution (35 parts by weight as acrylic rubber 1), 37.5 parts by weight of phenoxy resin solution (15 parts by weight as phenoxy resin), conductive coated particles Was changed to 4 parts by weight and SH6040 was 1 part by weight, and the film-like circuit connecting material was obtained in the same manner as in Example 1 except that EA-1010N was not used. It was.

Comparative Example 2
50 parts by weight of HX-3941HP, 37.5 parts by weight of the same phenoxy resin solution as in Example 1 (15 parts by weight as phenoxy resin), 250 parts by weight of the solution of acrylic rubber 1 (25 parts by weight as acrylic rubber 1) 100 parts by weight (10 parts by weight as a solid content) of a solution of 10% by weight acrylic rubber 2 obtained by dissolving acrylic rubber 2 in a mixed solvent of toluene / ethyl acetate = 50/50, and conductive coated particles 4 parts by weight and 1 part by weight of SH6040 were blended to obtain a mixed solution. Using the obtained mixed solution, a film-like circuit connecting material was obtained in the same manner as in Example 1.

Comparative Example 3
50 parts by weight of HX-3941HP, 250 parts by weight of a 10% by weight solution of acrylic rubber 1 as an acrylic rubber (25 parts by weight as a solid content), and 37.5 parts by weight of the 40% by weight solution of PKHC described above as a film forming component (15 parts by weight as a solid content), 50 parts by weight of an ethylene-vinyl acetate copolymer solution obtained by dissolving an ethylene-vinyl acetate copolymer in toluene (10 parts as an ethylene-vinyl acetate copolymer). Parts by weight), 4 parts by weight of conductive particles and 1 part by weight of SH6040 were blended to obtain a mixed solution. Using the obtained mixed solution, a film-like circuit connecting material was obtained in the same manner as in Example 1.

Circuit connection (COF)
A circuit connection material of each of the examples and comparative examples was pasted on an ITO-glass substrate having a thin layer of indium oxide (ITO) formed on the entire surface of a 0.7 mm thick glass substrate with a PET film attached thereto, 80 Temporary connection was performed by heating and pressurizing at 1 ° C. for 5 seconds. Thereafter, the PET film is peeled off, and a flexible circuit board (COF-TEG) in which a copper circuit (line width 25 μm, pitch 50 μm, thickness 8 μm) is directly formed on a 38 μm-thick polyimide film is used. It was placed in the direction adjacent to the connecting material. In that state, the ITO-glass substrate and the COF-TEG are connected under the conditions of 180 ° C., 3 MPa, 15 seconds, and a width of 2.0 mm, and the connection portion where the ITO-glass substrate and the COF-TEG are connected A connection structure having was obtained.

Adhesive strength The initial adhesive strength of the connection structure produced as described above was measured under the conditions of 90 ° peeling and peeling speed of 50 mm / min. Furthermore, the connection structure was subjected to a high-temperature and high-humidity treatment that was allowed to stand in a high-temperature and high-humidity tank at 85 ° C./85% RH for 500 hours.

Connection Reliability The resistance value between adjacent circuits of COF-TEG at the connection part of the connection structure was measured using a multimeter. The measurement was performed at an initial stage and after being treated for 500 hours in a high-temperature and high-humidity bath at 85 ° C./85% RH. The resistance value between adjacent circuits was measured at 150 locations, and x + 3σ was calculated from the obtained measurement value. It was determined that the connection reliability was good when the value of x + 3σ after the high temperature and high humidity treatment was within twice the initial value.

Storage stability (pot life)
A connection structure was produced in the same manner as described above using the circuit connection material after storage for 4 weeks at 25 ° C. and 60% RH. About the obtained connection structure, the connection reliability after an initial stage and a high-temperature, high-humidity process was evaluated similarly to the above. As a result, Examples 1 and 2 and Comparative Example 1 showed stable connection resistance and good storage stability. On the other hand, Comparative Example 2 had a high initial connection resistance, and the resistance increased rapidly after the high temperature and high humidity treatment, so that the storage stability was low. In Comparative Example 3, since the initial adhesive strength of the untreated product was lower than that of Comparative Example 1, the storage stability was not evaluated.

  The evaluation results are summarized in Table 1. In Examples 1 and 2, high adhesive strength was maintained even after high temperature and high humidity treatment, and connection reliability and storage stability were also good. On the other hand, the comparative example was insufficient in any one of the adhesive strength after high-temperature, high-humidity processing, connection reliability, and storage stability. That is, according to the present invention, it is possible to maintain high adhesive strength under high temperature and high humidity even when used for mounting COF, and at the same time, excellent connection reliability and storage stability. It was confirmed that a circuit connecting material that expresses the above is provided.

It is sectional drawing which shows one Embodiment of a circuit connection material. It is sectional drawing which shows one Embodiment of a connection structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Circuit connection material, 1a ... Connection part, 3 ... Adhesive layer, 5 ... Conductive particle, 10 ... 1st circuit member, 11 ... 1st board | substrate, 13 ... 1st circuit electrode, 20 ... 2nd Circuit member, 21 ... second substrate, 23 ... second circuit electrode, 100 ... connection structure.

Claims (3)

(1) an epoxy resin;
(2) a latent curing agent;
(3) a compound having an epoxy group and an acrylate group;
Containing
Circuit connection material for electrically connecting opposing circuit electrodes.   The circuit connection material according to claim 1, wherein the latent curing agent is an anionic polymerization type latent curing agent. A first circuit member having a first substrate and a first circuit electrode formed on a main surface of the first substrate;
A second substrate and a second circuit electrode formed on the main surface of the second substrate, the second circuit electrode and the first circuit electrode being arranged to face each other, and the second circuit A second circuit member having an electrode electrically connected to the first circuit electrode;
A connecting portion interposed between the first circuit member and the second circuit member;
With
The connection structure is a connection structure that is a cured product of the circuit connection material according to claim 1.

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