JPWO2019013336A1 - Conductive adhesive composition and connection structure using the same - Google Patents

Abstract

Disclosed is a conductive adhesive composition containing (A) conductive particles, (B) thermosetting resin, (C) flux activator, and (D) curing catalyst. The conductive particles include a metal having a melting point of 200° C. or lower. The average particle diameter of the conductive particles is 0.01 to 10 μm. The flux activator includes a compound having a hydroxyl group and a carboxyl group. The conductive adhesive composition is used to electrically connect the circuit board 2 and the electronic component 3 mounted on the circuit board 2.

Description

The present invention relates to a conductive adhesive composition used for electrically connecting an electronic component and a circuit board, and a connection structure using the same.

2. Description of the Related Art In recent years, as electronic devices have become smaller and thinner, and electronic components have become highly integrated, the area of the electrode pads arranged on the electronic components and the circuit board has been reduced, and the pitch between the electrode pads has been narrowed. There is a demand for high-density mounting of electronic components on such fine wiring patterns of electronic devices. Therefore, when mounting an electronic component on a substrate having electrodes arranged at a narrow pitch, there has been proposed a connecting material capable of connecting the substrate and the electronic component without causing a short circuit between the electrodes. (See Patent Document 1).

However, when the pitch between the electrodes is further narrowed and at the same time the electrode pad size is further reduced, a short circuit between the electrodes occurs when a conventional connecting material is used, which causes a conduction failure. .. Further, as electronic devices become thinner, warpage becomes apparent due to thermal history during heating connection, and it is also a major issue to reduce the warpage. Therefore, there is a demand for a joining method and a connecting material that achieve both narrow pitch connectivity and warpage resistance.

To mount electronic components on a circuit board or the like, a joining method using Sn-Ag-Cu solder, which is lead-free solder, is widely known. However, the Sn-Ag-Cu solder has a high connection temperature of 260° C., and when the electronic device is made thin, there is a problem that the warpage significantly increases due to the thermal history thereof. In order to reduce warpage, Sn-Bi solder having a melting point of 138° C. is also used as lead-free solder that can be connected at a lower temperature. However, although the connection method using Sn-Bi solder can reduce the warp of the substrate, the brittleness of the Sn-Bi solder itself causes a problem that the metal joint is broken during the temperature cycle test, resulting in poor conduction.

In order to overcome these problems, a conductive adhesive in which Sn-Bi metal particles are dispersed in a thermosetting resin to form a paste has been proposed (see Patent Document 2). Such a thermosetting conductive adhesive can improve the resistance to a temperature cycle test by using a thermosetting resin as a binder component.

JP, 2014-17248, A JP, 2006-199937, A

When applying the conductive adhesive composition for connecting the electrode pads that are downsized or the electrodes that are arranged at a narrow pitch, to prevent a short circuit due to the bridge between the electrodes and to ensure sufficient conduction with a small amount of application. In order to realize it, it is effective to some extent to reduce the size of the conductive particles in the conductive adhesive composition.

However, in the case of conductive particles having an average particle size of 10 μm or less, since the specific surface area is large, the amount of the oxide film formed on the surface of the conductive particles tends to increase, which tends to significantly lower the meltability and the bondability. When the meltability and the bondability decrease, the conductivity of the conductive adhesive decreases. In addition, the unmelted conductive particles may float to a region outside the electrode pad, which may cause a short circuit between the electrodes. If a large amount of flux activator is added to remove the oxide film on the surface of the conductive particles in order to maintain the meltability and bondability of the conductive particles, the curability of the conductive adhesive decreases. However, the decrease in the adhesive strength after curing tends to become apparent.

The present invention has been made in view of the above circumstances, and is for electrically connecting a circuit board and an electronic component mounted on the circuit board, which contains conductive particles having an average particle diameter of 10 μm or less including a metal. With respect to the conductive adhesive composition used for, it is intended to suppress the short circuit between the electrodes and further improve the adhesive strength and the conductivity.

One aspect of the present invention provides a conductive adhesive composition containing (A) conductive particles, (B) thermosetting resin, (C) flux activator, and (D) curing catalyst. The conductive particles include a metal having a melting point of 200° C. or lower. The average particle diameter of the conductive particles is 0.01 to 10 μm. The flux activator includes a compound having a hydroxyl group and a carboxyl group. The conductive adhesive composition is used to electrically connect a circuit board and an electronic component mounted on the circuit board. In other words, one aspect of the present invention is an application of the conductive adhesive composition for electrically connecting a circuit board and an electronic component mounted on the circuit board, or the conductive adhesive composition. The present invention relates to an application for manufacturing a connection structure having a circuit board and electronic components mounted on the circuit board.

The conductive adhesive composition according to the present invention is for electrically connecting a circuit board and an electronic component mounted on the circuit board while containing conductive particles containing a metal and having an average particle size of 10 μm or less. When used, it is possible to further improve the adhesive strength and the conductivity while suppressing the short circuit between the electrodes. For example, even if the conductive particles have a small particle size, good conductivity can be provided without lowering the melting property. Further provided is a conductive adhesive composition that separates electrodes (connection terminals) arranged at a narrow pitch without bridging and forms a good connection state without short-circuiting.

The content of the flux activator may be 4.0 to 8.5 mass% with respect to the mass of the conductive particles.

The metal having a melting point of 200° C. or less contained in the conductive particles may be at least one selected from bismuth, indium, tin and zinc. The specific surface area of the conductive particles may be 0.060 to 90 m ² /g.

The curable resin may include an epoxy resin.

The conductive adhesive composition may be in paste form at 25°C.

The conductive adhesive composition has a circuit board having a base material and two or more connecting terminals arranged on the main surface of the base material, and electrically connecting the two or more connecting terminals with the connecting terminals of the electronic component. May be used to make a physical connection. In this case, two or more connection terminals of the circuit board may be arranged on the main surface of the base material at intervals of 200 μm or less.

Another aspect of the present invention is a circuit board having a base material and two or more connection terminals provided on the main surface of the base material, and two or more connection terminals facing the two or more connection terminals of the circuit board. There is provided a connection structure including: an electronic component having: and a connection portion that is disposed between the circuit board and the electronic component and that joins them. The connection portion includes a conductive portion arranged between the connection terminal of the circuit board and the connection terminal of the electronic board and electrically connecting them, and the conductive portion has the conductive adhesive according to the present invention. The conductive particles included in the composition are included. The connection portion may further include a resin portion provided around the conductive portion. The electronic component may include at least one selected from the group consisting of a driver IC, a module component incorporating a sensor element, a Schottky barrier diode, and a thermoelectric conversion element. The substrate may be a flexible substrate.

The conductive adhesive composition according to the present invention is used for electrically connecting a circuit board and an electronic component mounted on the circuit board, while containing conductive particles containing a metal and having an average particle size of 10 μm or less. When this occurs, it is possible to further improve the adhesive strength and the conductivity while suppressing the short circuit between the electrodes. The conductive adhesive composition according to the present invention is also advantageous in terms of lowering the reflow heating temperature in the step of mounting electronic components on a circuit board and suppressing the warpage of small and thin devices. Since the conductive adhesive composition according to the present invention tends to have a low viscosity, it is also suitable for connecting fine connection terminals with a small amount of coating.

The connection structure having the connection portion formed of the conductive adhesive composition is excellent not only in resistance to expansion and contraction and bending but also in resistance to a temperature cycle test.

It is a schematic cross section which shows one Embodiment of a connection structure. It is a schematic cross section which shows one Embodiment of a connection structure.

Hereinafter, some embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

The conductive adhesive composition according to one embodiment contains (A) conductive particles, (B) thermosetting resin, (C) flux activator, and (D) curing catalyst.

The conductive particles (A) contain a metal having a melting point of 200° C. or lower. The melting point of the metal contained in the conductive particles may be 180° C. or lower, or 150° C. or lower. The lower limit of the melting point of the metal in the conductive particles is not particularly limited, but is about 100°C. When such conductive particles are used in the conductive adhesive composition, it is considered that the conductive particles are melted and aggregated at a relatively low temperature, and the aggregates contribute to the electrical connection of the connection terminals. When the metal contained in the conductive particles is an alloy containing two or more metal species, the melting point of the alloy may be 200° C. or less.

The metal in the conductive particles may be composed of a metal other than lead from the viewpoint of reducing the environmental load. As the metal contained in the conductive particles, for example, one kind of metal simple substance selected from tin (Sn), bismuth (Bi), indium (In), zinc (Zn), or the like, or two or more selected from these Examples include alloys containing metal species. Since the alloy can obtain better connection reliability, platinum (Pt), gold (Au), silver (Ag), A high melting point component selected from copper (Cu), nickel (Ni), palladium (Pd), aluminum (Al) and the like may be further contained.

Specific examples of the metal forming the conductive particles include Sn42-Bi58 solder (melting point 138°C), Sn48-In52 solder (melting point 117°C), Sn42-Bi57-Ag1 solder (melting point 139°C), Sn90-Ag2. Examples include -Cu0.5-Bi7.5 solder (melting point 189°C), Sn96-Zn8-Bi3 solder (melting point 190°C), Sn91-Zn9 solder (melting point 197°C). They show a distinctive solidification behavior after melting. Solidification behavior means that the metal cools and solidifies after melting. Among these, Sn42-Bi58 solder may be used from the viewpoint of availability and effect. These may be used alone or in combination of two or more.

The average particle size of the conductive particles may be 0.01 to 10 μm. When the average particle size is 0.01 μm or more, the viscosity of the conductive adhesive composition does not become too high, so that workability tends to be improved, and the amount of the metal oxide film formed on the surface of the conductive particles. Is suppressed, and the conductive particles are thereby easily melted, so that the desired connected state tends to be easily maintained. When the average particle diameter of the conductive particles is 10 μm or less, there is a reduced possibility that adjacent electrodes may be bridged to each other and a short circuit may occur between the electrodes when the electrodes arranged at a narrow pitch are connected to the electronic component. When the conductive adhesive composition is applied, it tends to be difficult to apply a small amount to an electrode pad having a small area by any of the printing method, the transfer method and the dispensing method. From the viewpoint of further improving the coatability and workability of the conductive adhesive composition, the average particle size of the conductive particles may be 0.1 to 10 μm or 0.1 to 8 μm. In particular, from the viewpoint of improving the storage stability of the conductive adhesive composition and the mounting reliability of the cured product, the average particle size of the conductive particles may be 1 to 5 μm. Here, the average particle diameter of the conductive particles is a value obtained by a laser diffraction/scattering method.

The specific surface area of the conductive particles ^may be 0.060m ² / g~90m 2 / g.

The conductive particles may be metal particles composed only of metal, or may be core particles made of a solid material other than metal such as ceramics, silica, and resin material, and the surface of the core particles may be coated to have a melting point of 200° C. It may be a composite particle having a metal film made of the following metal, or may be a combination of the metal particle and the composite particle.

The content of the conductive particles may be 5 to 95 mass% with respect to the total mass of the conductive adhesive composition. When the content of the conductive particles is 5% by mass or more, the conductivity of the cured product of the conductive adhesive composition tends to be improved. When the content of the conductive particles is 95% by mass or less, the viscosity of the conductive adhesive composition becomes low, so that workability tends to be improved, and the adhesive in the conductive adhesive composition is relatively present. Since the number of components increases, the mounting reliability of the cured product tends to improve. The content of the conductive particles may be 10 to 90% by mass from the viewpoint of improving workability or conductivity, and is 15 to 15 from the viewpoint of enhancing mounting reliability of the cured product of the conductive adhesive composition. It may be 85% by mass. Here, when the conductive adhesive composition includes a diluent described below, the content of each component is determined based on the mass of the component other than the diluent. The diluent here means a component such as an organic solvent other than the reactive diluent described later.

In addition to the conductive particles containing a metal having a melting point of 200° C. or lower, the conductive adhesive composition may include (a1) high melting point conductive particles containing a metal having a melting point of higher than 200° C. Examples of the metal having a melting point higher than 200° C. include a single metal element selected from Pt, Au, Ag, Cu, Ni, Pd, Al and the like, or an alloy composed of two or more metal elements. Specific examples of the high-melting point conductive particles include Au powder, Ag powder, Cu powder, and Ag-plated Cu powder. As a commercially available high melting point conductive particle, "MA05K" (manufactured by Hitachi Chemical Co., Ltd.), which is a silver-plated copper powder, is available.

When (A) conductive particles containing a metal having a melting point of 200° C. or less and (a1) conductive particles containing a metal having a melting point of more than 200° C. are combined, the mass ratio of (A):(a1) is 99: It may be in the range of 1 to 50:50, or 99:1 to 60:40.

The thermosetting resin (B) has a function of adhering an adherend, and also functions as a binder component that bonds the conductive particles in the conductive adhesive composition and a filler added as necessary to each other. Examples of such thermosetting resin include thermosetting organic polymer compounds such as epoxy resin, (meth)acrylic resin, maleimide resin and cyanate resin, and precursors thereof. Here, the (meth)acrylic resin means a methacrylic resin and an acrylic resin. The thermosetting resin may be a compound having a polymerizable carbon-carbon double bond, which is represented by a (meth)acrylic resin and a maleimide resin, or an epoxy resin. These thermosetting resins are excellent in heat resistance and adhesiveness, and can be handled in a liquid state if dissolved or dispersed in an organic solvent as required, and thus are excellent in workability. An epoxy resin may be used from the viewpoint of easy availability and reliability. The above-mentioned thermosetting resins may be used alone or in combination of two or more.

The epoxy resin is not particularly limited as long as it is a compound having two or more epoxy groups in its molecule. Examples of the epoxy resin include epoxy resins derived from bisphenol A, bisphenol F, bisphenol AD and the like and epichlorohydridone.

A commercially available epoxy resin can be obtained. Specific examples thereof include AER-X8501 (manufactured by Asahi Kasei Co., Ltd., trade name) which is a bisphenol A type epoxy resin, R-301 (manufactured by Mitsubishi Chemical Co., trade name), YL-980 (manufactured by Mitsubishi Chemical Co., Ltd., (Trade name), YDF-170 (manufactured by Tohto Kasei Co., Ltd., trade name) which is a bisphenol F type epoxy resin, YL-983U (manufactured by Mitsubishi Chemical Co., trade name), R-1710 (bisphenol AD type epoxy resin). Mitsui Chemicals, Inc., trade name), phenol novolac type epoxy resin N-730S (DIC Co., Ltd. product name), Quatrex-2010 (Dow Chemical Co., Ltd., trade name), cresol novolac type epoxy resin YDCN-702S (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name), EOCN-100 (manufactured by Nippon Kayaku Co., Ltd., trade name), EPPN-501 (manufactured by Nippon Kayaku Co., Ltd., trade name) which is a polyfunctional epoxy resin. ), TACTIX-742 (trade name, manufactured by Dow Chemical Co., Ltd.), VG-3010 (trade name, manufactured by Mitsui Chemicals Co., Ltd.), 1032S (trade name, manufactured by Mitsubishi Chemical Co., Ltd.), an epoxy resin having a naphthalene skeleton. HP-4032 (manufactured by DIC Corporation, trade name), alicyclic epoxy resin EHPE-3150, CEL-3000 (both manufactured by Daicel Corporation, trade name), DME-100 (manufactured by Shin Nippon Rika Co., Ltd., Trade name), EX-216L (Nagase Kasei Co., Ltd., trade name), Aliphatic epoxy resin W-100 (New Nippon Rika Co., Ltd. trade name), Amine type epoxy resin ELM-100 ( Sumitomo Chemical Co., Ltd. product name), YH-434L (Nippon Steel & Sumikin Chemical Co., Ltd. product name), TETRAD-X, TETRAD-C (both Mitsubishi Gas Chemical Co., Ltd. product name), 630, 630LSD (both Mitsubishi Chemical Co., Ltd., trade name), Resorcin-type epoxy resin Denacol EX-201 (Nagase Kasei Kogyo Co., Ltd., trade name), Neopentyl glycol type epoxy resin Denacol EX-211 (Nagase Kasei Co., Ltd.) , Trade name), 1,6-hexanediol diglycidyl ether Denacol EX-212 (manufactured by Nagase Chemical Industry Co., Ltd., trade name), ethylene-propylene glycol type epoxy resin Denacol EX series (EX-810, 811, 850, 851, 821, 830, 832, 841, 861 (all are Nagase Kasei Co., Ltd. Formula company, trade name)), and epoxy resins E-XL-24 and E-XL-3L represented by the following general formula (I) (both manufactured by Mitsui Chemicals, Inc., trade name). Among these epoxy resins, one or more selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, and amine type epoxy resin, which have few ionic impurities and excellent reactivity, are selected. May be.

式（Ｉ）中、ｋは１〜５の整数を示す。

In formula (I), k represents an integer of 1 to 5.

The above epoxy resins may be used alone or in combination of two or more.

When the thermosetting resin contains an epoxy resin, the conductive adhesive composition may further contain an epoxy compound having only one epoxy group in one molecule as a reactive diluent. Such epoxy compounds are commercially available. Specific examples thereof include PGE (manufactured by Nippon Kayaku Co., Ltd., trade name), PP-101 (manufactured by Nippon Steel & Sumitomo Metal Corporation, trade name), ED-502, ED-509, ED-509S (manufactured by ADEKA CORPORATION). , Trade name), YED-122 (manufactured by Mitsubishi Chemical Corporation, trade name), KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name), TSL-8350, TSL-8355, TSL-9905 (Toshiba Silicone Co., Ltd.) Manufactured, trade name). These may be used alone or in combination of two or more.

When the conductive adhesive composition contains the reactive diluent, the content thereof may be in the range that does not significantly impair the effects of the present invention, and is 0.1 to 30% by mass with respect to the total amount of the epoxy resin. It may be.

The thermosetting resin may include a (meth)acrylic resin. The (meth)acrylic resin is composed of a compound having a polymerizable carbon-carbon double bond. Examples of such compounds include monoacrylate compounds, monomethacrylate compounds, diacrylate compounds, and dimethacrylate compounds.

Examples of the monoacrylate compound include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, and 2-. Ethylhexyl acrylate, nonyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, tridecyl acrylate, hexadecyl acrylate, stearyl acrylate, isostearyl acrylate, cyclohexyl acrylate, isobornyl acrylate, diethylene glycol acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-butoxyethyl acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, dicyclopentenyloxyethyl acrylate, 2-phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol acrylate, 2 -Benzoyloxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, benzyl acrylate, 2-cyanoethyl acrylate, γ-acryloxyethyl trimethoxysilane, glycidyl acrylate, tetrahydrofurfuryl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, Included are acryloxyethyl phosphate and acryloxyethyl phenyl acid phosphate.

Examples of the monomethacrylate compound include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2- Ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, hexadecyl methacrylate, stearyl methacrylate, isostearyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, diethylene glycol methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-butoxyethyl methacrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, dicyclopentenyloxyethyl methacrylate, 2-phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate, phenoxypolyethylene glycol methacrylate, 2 -Benzoyloxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, benzyl methacrylate, 2-cyanoethyl methacrylate, γ-methacryloxyethyl trimethoxysilane, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, Methacryloxyethyl phosphate and methacryloxyethyl phenyl acid phosphate are mentioned.

Examples of the diacrylate compound include ethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 1,3-butanediol diacrylate, neo. Pentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, bisphenol A, bisphenol F or bisphenol AD 1 mol and glycidyl acrylate 2 Moles of reactants, bisphenol A, bisphenol F or bisphenol AD polyethylene oxide adduct diacrylate, bisphenol A, bisphenol F or bisphenol AD polypropylene oxide adduct diacrylate, bis(acryloxypropyl)polydimethylsiloxane and bis (Acryloxypropyl)methylsiloxane-dimethylsiloxane copolymers.

Examples of the dimethacrylate compound include ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,3-butanediol dimethacrylate, and neo. Pentyl glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, bisphenol A, bisphenol F or bisphenol AD 1 mol and glycidyl methacrylate 2 Moles of reactant, dimethacrylate of polyethylene oxide adduct of bisphenol A, bisphenol F or bisphenol AD, polypropylene oxide adduct of bisphenol F or bisphenol AD, bis(methacryloxypropyl)polydimethylsiloxane and bis(methacryloxypropyl)methyl Included are siloxane-dimethyl siloxane copolymers.

These compounds may be used alone or in combination of two or more. When the thermosetting resin contains a (meth)acrylic resin, these compounds may be preliminarily polymerized before use, and these compounds are mixed with conductive particles, a flux activator, etc., and polymerization is performed at the same time as mixing. May be. The compound having a polymerizable carbon-carbon double bond in these molecules may be used alone or in combination of two or more.

When the thermosetting resin contains a (meth)acrylic resin, the conductive adhesive composition may contain a radical polymerization initiator. The radical polymerization initiator may be an organic peroxide from the viewpoint of effectively suppressing voids. From the viewpoint of improving the curability and viscosity stability of the adhesive component, the decomposition temperature of the organic peroxide may be 130°C to 200°C.

As the radical polymerization initiator, a commonly used one can be used. Examples thereof include benzoyl peroxide, peroxides such as t-butylperoxy-2-ethylhexanoate, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile.

The content of the radical polymerization initiator may be 0.01 to 20% by mass, 0.1 to 10% by mass, or 0.5 to 5% by mass with respect to the total amount of the conductive adhesive composition.

As the (meth)acrylic resin, commercially available products can be used. Specific examples thereof include FINEDIC A-261 (manufactured by DIC Corporation, trade name), FINEDIC A-229-30 (manufactured by DIC Corporation, trade name) and the like.

The content of the thermosetting resin in the conductive adhesive composition is 1 to 60% by mass, 5 to 40% by mass, or 10 to 30% by mass with respect to the total mass of the conductive adhesive composition. Good.

The flux activator (C) is a component having a function of removing an oxide film formed on the surface of the conductive particles. By using such a flux activator, the oxide film that hinders the melting and aggregation of the conductive particles is removed. The flux activator according to one embodiment includes a compound containing a hydroxyl group and a carboxyl group. This compound has good flux activity and can be reactive with epoxy resins that can be used as thermosetting resins. The compound having a hydroxyl group and a carboxyl group may be an aliphatic dihydroxycarboxylic acid from the viewpoint of exhibiting a good oxide film removing ability even when the conductive particles have a small particle size and a large oxide film amount. Specifically, the flux activator may contain a compound represented by the following general formula (V) or tartaric acid.

In formula (V), R5 represents an alkyl group having 1 to 5 carbon atoms. From the viewpoint of more effectively exerting the above-mentioned effects of the present invention, R5 may be a methyl group, an ethyl group or a propyl group. m and n each independently represent an integer of 0 to 5. From the viewpoint of more effectively exerting the above-mentioned effects of the present invention, m may be 0 and n may be 1, or both m and n may be 1.

Examples of the compound represented by the general formula (V) include 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butanoic acid, and 2,2-bis(hydroxymethyl)pentane. Acid etc. are mentioned. The flux activator may contain at least one compound selected from these.

The content of the flux activator is 0.5 to 50% by mass, 0.5 to 40% by mass, or 4. with respect to the mass of the conductive particles, from the viewpoint of more effectively exhibiting the above-described effects of the present invention. It may be 0 to 8.5 mass %. Further, the content of the flux activator may be 1 to 35% by mass from the viewpoint of storage stability and conductivity. When the content of the flux activator is 0.5% by mass or more, the meltability of the metal increases, so that the effect of improving conductivity tends to be small. When the content of the flux activator is 50% by mass or less, storage stability and printability tend to be improved.

The (D) curing catalyst is a component that accelerates the curing of the (B) thermosetting resin. The curing catalyst (D) may be a compound having an imidazole group from the viewpoints of curability at a desired curing temperature, length of pot life, heat resistance of the cured product, etc., and is an imidazole-based epoxy resin curing agent. May be. Commercially available imidazole-based epoxy resin curing agents include 2P4MHZ-PW (2-phenyl-4-methyl-5-hydroxymethylimidazole), 2PHZ-PW (2-phenyl-4,5-dihydroxymethylimidazole), C11Z-. CN (1-cyanoethyl-2-undecylimidazole), 2E4MZ-CN (1-cyanoethyl-2-ethyl-4-methylimidazole), 2PZ-CN (1-cyanoethyl-2-phenylimidazole), 2MZ-A (2 ,4-diamino-6-[2'methylimidazolyl-(1')]-ethyl-s-triazine), 2E4MZ-A(2,4-diamino-6-[2'-ethyl-4'methylimidazolyl-( 1')]-Ethyl-s-triazine), 2MAOK-PW (2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct) (both Shikoku Kasei Co., Ltd., trade name) and the like. These curing catalysts may be used alone or in combination of two or more.

The content of the curing catalyst may be 0.01 to 90 parts by mass, or 0.1 to 50 parts by mass with respect to 100 parts by mass of the epoxy resin. When the content of the curing catalyst is 0.01 part by mass or more, the curability tends to be improved. When the content of the curing catalyst is 90 parts by mass or less, workability when handling the conductive adhesive composition tends to be improved.

In addition to the above-mentioned components, the conductive adhesive composition may include a flexible agent for stress relaxation, a diluent for improving workability, an adhesive strength improving agent, a wettability improving agent, and a defoaming agent, if necessary. One or more additives selected from the group consisting of agents may be included. In addition to these components, the conductive adhesive composition may contain various additives as long as the effects of the present invention are not impaired.

The conductive adhesive composition may contain a coupling agent such as a silane coupling agent or a titanium coupling agent for the purpose of improving the adhesive strength. Examples of the silane coupling agent include "KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd., and the like. For the purpose of improving wettability, the conductive adhesive composition may contain an anionic surfactant, a fluorinated surfactant and the like. The conductive adhesive composition may contain silicone oil or the like as a defoaming agent. The adhesiveness improver, the wettability improver, and the defoaming agent may be used alone or in combination of two or more. The content of these may be 0.1 to 10 mass% with respect to the total mass of the conductive adhesive composition.

As the flexibilizer, liquid polybutadiene (manufactured by Ube Industries, Ltd., trade name “CTBN-1300×31”, “CTBN-1300×9”, manufactured by Nippon Soda Co., Ltd., trade name “NISSO-PB-C-2000” ) And the like. The content of the flexible agent may be 0.1 to 500 parts by mass with respect to 100 parts by mass of the thermosetting resin.

The conductive adhesive composition may contain a diluent, if necessary, in order to improve workability during preparation of the paste composition and coating workability during use. The diluent is an organic solvent having a relatively high boiling point such as butyl carbitol, butyl carbitol acetate, butyl cellosolve, carbitol, butyl cellosolve acetate, carbitol acetate, dipropylene glycol monomethyl ether, ethylene glycol diethyl ether and α-terpineol. May be. The content of the diluent may be 0.1 to 30 mass% with respect to the total mass of the conductive adhesive composition.

The conductive adhesive composition may contain a filler. Examples of the filler include polymer particles such as acrylic rubber and polystyrene, and inorganic particles such as diamond, boron nitride, aluminum nitride, alumina, and silica. You may use these fillers individually by 1 type or in mixture of 2 or more types.

The conductive adhesive composition may further contain a curing agent to adjust the curing rate of the epoxy resin.

The curing agent is not particularly limited as long as it is conventionally used, and a commercially available one is available. Examples of commercially available curing agents include phenol novolac resin H-1 (manufactured by Meiwa Kasei Co., Ltd., trade name), VR-9300 (Mitsui Chemicals, Inc., trade name), and phenol aralkyl resin XL-225. (Trade name, manufactured by Mitsui Chemicals, Inc.), MTPC (trade name, manufactured by Honshu Chemical Industry Co., Ltd.), which is a p-cresol novolac resin represented by the following general formula (II), and AL-, which is an allylated phenol novolac resin. VR-9300 (manufactured by Mitsui Chemicals, Inc., trade name) and PP-700-300 (manufactured by JXTG Energy Co., Ltd., trade name), which is a special phenol resin represented by the following general formula (III), may be mentioned.

In formula (II), a plurality of R1's each independently represent a monovalent hydrocarbon group. R1 may be a methyl group or an allyl group. q represents an integer of 1 to 5. In formula (III), R2 represents an alkyl group. R2 may be a methyl group or an ethyl group. R3 represents a hydrogen atom or a monovalent hydrocarbon group. p shows the integer of 2-4.

As the curing agent, those conventionally used as a curing agent such as dicyandiamide can be used, and commercially available products are available. Examples of commercially available products include, for example, dibasic acid dihydrazide represented by the following general formula (IV): ADH, PDH, and SDH (all manufactured by Nippon Fine Chem Co., Ltd., trade name), a reaction product of an epoxy resin and an amine compound. Microcapsule type hardener consisting of Novacure (manufactured by Asahi Kasei Corp., trade name). These curing agents may be used alone or in combination of two or more.

In formula (IV), R4 represents a divalent aromatic group or a linear or branched alkylene group having 1 to 12 carbon atoms. R4 may be a m-phenylene group or a p-phenylene group.

From the viewpoint of storage stability and curing time, the conductive adhesive may not contain a curing agent substantially. The term "substantially free from" means that the content is 0.05% by mass or less based on the total mass of the conductive adhesive composition.

In the conductive adhesive composition, from the viewpoint of more effectively exhibiting the above effects, the compounding ratio of the component (hereinafter referred to as the adhesive component) other than the (A) conductive particles to the (A) conductive particles (the adhesive component). The mass ratio of the conductive particles may be 5/95 to 50/50 when the total of these particles is 100. From the viewpoint of adhesiveness, conductivity, and workability, the compounding ratio may be 10/90 to 30/70. When the blending ratio is 5/95 or more, the viscosity of the conductive adhesive composition does not become too high, so that workability tends to be ensured, and the effect of improving the adhesiveness tends to increase. If the mixing ratio is 50/50 or more, the effect of improving the conductivity tends to be large.

Each of the components described above may be combined with any of those exemplified.

The electrically conductive adhesive composition can be obtained by heating each of the above-mentioned components at once or a plurality of times, if necessary, and mixing, dissolving, disintegrating, kneading, or dispersing. The conductive adhesive composition may be in the form of a paste in which each component is uniformly dispersed. Examples of the dispersing/dissolving device used in this case include a usual stirrer, a raker, a three-roller, and a planetary mixer. The conductive adhesive composition may be in paste form at 25°C. The viscosity of the conductive adhesive composition may be 5 to 400 Pa·s at 25°C.

According to the conductive adhesive composition of the present embodiment described above, it is possible to provide a mounted component to a circuit board having a small area electrode pad or electrodes arranged at a narrow pitch without causing a short circuit between the electrodes. It is possible to connect with various conductivity. The conductive adhesive composition of this embodiment can lower the reflow heating temperature in the step of mounting an electronic component on a circuit board having electrodes arranged at a sandwiching pitch. When the temperature is lowered, the warp of the circuit board can be suppressed. The connection part formed by the conductive adhesive composition of the present embodiment can have a conductive part containing conductive particles and a resin part formed of an insulating adhesive component. Reinforcement with the resin portion can contribute to improving the temperature cycle test resistance of the connection structure.

Next, an electronic component mounting board as an example of the connection structure will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a connection structure. The connection structure 1 shown in FIG. 1 includes a circuit board 2 having a base material 5 and two or more connection terminals 7 formed on the main surface of the base material 5, an electronic component 3 facing the circuit board 2, and a circuit. The electronic component mounting substrate is provided with a connecting portion 8 that is disposed between the substrate 2 and the electronic component 3 and that joins them. The electronic component 3 has a main body portion 4 and two or more connection terminals 6. The connecting portion 8 is composed of a conductive portion 8a and a resin portion 8b formed around the conductive portion 8a. The connection portion 8 is arranged between the connection terminal 7 of the circuit board 2 and the connection terminal 6 of the electronic component 3, and electrically connects them. The connection part 8 is a cured product of the conductive adhesive composition according to the above-described embodiment. The conductive portion 8a mainly includes an aggregate of conductive particles contained in the conductive adhesive composition. The resin portion 8b mainly includes a cured product of an adhesive component that is contained in the conductive adhesive composition and includes a thermosetting resin and a curing catalyst. However, the resin portion 8b may include a small amount of conductive particles as long as the appropriate insulating property is maintained. The circuit board 2 and the electronic component 3 are joined to each other and electrically connected by the connecting portion 8.

For the connection structure 1, for example, a circuit board 2 and an electronic component 3 each having two or more connection terminals 7 and 6 are prepared, and conductive bonding is performed on the connection terminal 7 of the circuit substrate 2 or the connection terminal 6 of the electronic component 3. Of the electronic component on the circuit board 2 such that the step of applying the agent composition and the connection terminal 7 of the circuit board 2 and the connection terminal 6 of the electronic component 3 face each other via the applied conductive adhesive composition. 3 is arranged to obtain a temporary connection body having the circuit board 2, the conductive adhesive composition and the electronic component 3, and the conductive connection agent is cured by heating the temporary connection body, and A conductive portion 8a containing conductive particles in the conductive adhesive composition and electrically connecting the connection terminal 7 of the circuit board 2 and the connection terminal 6 of the electronic component 3 is formed, thereby containing the conductive portion 8a. It can be manufactured by a method including a step of obtaining a connection structure in which the circuit board 2 and the electronic component 3 are joined by the connection portion 8.

The conductive adhesive composition can be applied to a connection terminal of a circuit board or an electronic component by a method such as a dispensing method, a screen printing method, a stamping method. The heating of the temporary connection body can be performed using a heating device such as an oven or a reflow furnace. If necessary, the temporary connection body may be heated under pressure. In the process of heat-curing the conductive adhesive composition, the connecting portion 8 having the conductive portion 8a and the resin portion 8b is usually formed. The conductive portion 8a includes an aggregate formed by fusing conductive particles melted by heating. This aggregate joins with the connection terminals of the circuit board and the electronic component to form a metal connection path.

In the case of the connection structure 1 shown in FIG. 2, a conductive portion 8a formed of a conductive adhesive composition and a solder ball 10 are provided. The solder balls 10 are provided on the connection terminals 6 of the electronic component 3. The solder ball 10 and the connection terminal 7 of the circuit board 2 are electrically connected by the conductive portion 8a. That is, the connection terminal 7 of the circuit board 2 and the connection terminal 6 of the electronic component 3 are electrically connected via the conductive portion 8a and the solder ball 10. The connection terminals 7 of the circuit board 2 may be arranged on the main surface of the base material 5 with a space of 200 μm or less from each other.

In these connection structures, the conductive portion 8a is reinforced by the resin portion 8b. When the connection structure is subjected to heat history due to the temperature cycle test, a large amount of strain is applied to the connection portion and other constituent members due to warpage and the like. Since the conductive portion 8a is reinforced by the resin portion 8b, the deformation of the base material is stopped by the resin portion 7b, and the generation of cracks at the connection portion is suppressed.

Even when the cross-section along the thickness direction of the connection structure is viewed at the position where the connection terminal of the electronic component shows the maximum width, the area ratio between the conductive portion and the resin portion is 5:95 to 80:20. Good.

Although the embodiment of the present invention has been described above, 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, when the circuit board is a support board for mounting LEDs and the electronic component is an LED element, the connection board for mounting LEDs, the LED elements, and the connection for bonding and electrically connecting the support board and the LED elements And an LED device are configured. The connection part is a cured product of the conductive adhesive composition. The support substrate for mounting the LED and the LED element are not particularly limited.

When the circuit board is the support substrate for mounting the sensor element and the electronic component is the sensor element, the connection for electrically connecting the support substrate for mounting the sensor element, the sensor element, and the support substrate and the sensor element together And a module having a built-in sensor element. The connection part is a cured product of the conductive adhesive composition. The support substrate for mounting the sensor element and the sensor element are not particularly limited.

The electronic component may be at least one selected from the group consisting of a driver IC, a module component incorporating a sensor element, a Schottky barrier diode, and a thermoelectric conversion element. The substrate may be a flexible substrate. The connection structure may further include a sealing member provided around the resin portion.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The materials used in Examples and Comparative Examples are those produced by the following method or those obtained.

[Example 1]
17.7 parts by mass of YL980 (trade name of bisphenol F type epoxy resin manufactured by Mitsubishi Chemical Co., Ltd.), 0.9 parts by mass of 2P4MHZ-PW (trade name of imidazole compound manufactured by Shikoku Chemicals Co., Ltd.), and flux activity BHPA (2,2-bis(hydroxymethyl)propionic acid) as an agent was mixed with 6.4 parts by mass, and the mixture was passed through a three-roll three times to prepare an adhesive component.

Next, 75 parts by mass of Sn42-Bi58 particles (average particle size 5 μm, manufactured by Mitsui Mining & Smelting Co., Ltd., melting point: 138° C.), which are conductive particles, were added to 20 parts by mass of the adhesive component, and the resulting mixture was obtained. Was stirred using a planetary mixer, and defoaming treatment was performed at 500 Pa or less for 10 minutes to obtain a conductive adhesive composition.

[Examples 2-9, Comparative Examples 1-9]
The conductive adhesive compositions of Examples 2 to 9 and Comparative Examples 1 to 6 were obtained in the same manner as in Example 1 except that the composition shown in Table 1 was changed. In Comparative Examples 7 to 9, the following commercially available conductive adhesives were used.
<Conductive particles>
Sn42-Bi58 solder particles (Mitsui Mining & Smelting Co., Ltd., melting point 138° C.)
・Sn42-Bi58 10 μm particles: average particle size 10 μm
-Sn42-Bi58 10-25 [mu]m particles: average particle size exceeding 10 [mu]m and 25 [mu]m or less-Sn42-Bi58 20-38 [mu]m particles: average particle size 20-38 [mu]m
Sn42-Bi57-Ag1 solder particles (Mitsui Mining & Smelting Co., Ltd., melting point 139° C.)
-Sn42-Bi57-Ag1 5 μm particles: average particle size 5 μm
<Flux activator>
BHBA: 2,2-bishydroxymethylbutanoic acid tartaric acid glutaric acid adipic acid <other conductive adhesives>
Ag paste: Fujikura Kasei Co., Ltd. DOTITE (trade name)
Sn42-Bi58 cream solder: Senju Metal Industry Co., Ltd., Eco solder (trade name)
Sn96.5-Ag3-Cu0.5 cream solder: Eco-solder (trade name) manufactured by Senju Metal Industry Co., Ltd.

(Adhesion, conductivity, TCT resistance evaluation)
The characteristics of the conductive adhesive compositions according to Examples 1-9 and Comparative Examples 1-9 were measured by the following methods. The results are summarized in Tables 1 and 2. In the table, "flux/metal ratio (%)" means the ratio (mass %) of the flux activator to the conductive particles.

(1) Adhesiveness (adhesive strength)
About 0.5 mg of the conductive adhesive composition was applied on a silver-plated copper plate, and a rectangular plate-shaped copper plate with tin plating of 2 mm×2 mm×0.25 mm was pressure-bonded onto the copper plate to obtain a test piece. Then, the test pieces according to Examples 1 to 9 and Comparative Examples 1 to 8 were subjected to a heat history of 150° C. for 10 minutes. A thermal history of 260° C. for 10 minutes was applied to the test piece of Comparative Example 9. The adhesive strength (shear strength) at 25° C. of each test piece after the heat history was added was measured using a bond tester (2400, manufactured by DAGE) under the conditions of a shear rate of 500 μm/sec and a clearance of 100 μm.

(2) Conductivity (volume resistivity)
Two 1 mm×50 mm×0.03 mm strip-shaped gold-plated copper plates were attached so as to be orthogonal to each other via the conductive adhesive composition to obtain a test piece. The dimension of the adhesive layer in the orthogonal portion of the copper plate was 1 mm×1 mm×0.03 mm. Then, the same thermal history as the above (1) was added to the test piece. The volume resistivity of the subsequent test piece was measured by the four-terminal method.

(3) TCT resistance A rectangular flat plate-shaped thin FR4 of 100 mm×50 mm×0.5 mm in which two adjacent copper foil lands (0.2 mm×0.4 mm) are provided and the distance between the copper foil lands is 100 μm. The substrate was prepared. Then, the conductive adhesive composition was printed on the copper foil land using a metal mask (thickness 100 μm, opening size 0.2 mm×0.3 mm). A small chip resistor (0.2 mm×0.4 mm) having a distance between electrodes of 100 μm was placed thereon so that the electrode and the copper foil land were opposed to each other via the conductive adhesive composition. The same thermal history as in (1) above was added to the obtained component mounting board to obtain a test board for TCT resistance evaluation. The initial resistance of this test board was confirmed using a simple tester. Then, using a thermal shock tester, the test substrate was kept at −55° C. for 30 minutes, heated to 125° C. for 5 minutes, held at 125° C. for 30 minutes, and cooled to −55° C. for 5 minutes. It was subjected to a thermal shock test in which the temperature change was one cycle. The connection resistance of the test board after the thermal shock test was measured. The connection resistance of the test substrate was measured while increasing the number of cycles, and the number of cycles until the time when the resistance change rate within ±10% of the initial resistance was shown was used as an index of TCT resistance. In the table, "initial open" means that the initial conductivity was extremely low. "Initial short" means that a short had occurred before the thermal shock test.

Examples 1 to 9 all showed good adhesive strength, low volume efficiency, and TCT resistance. Almost no warp of the test substrate was observed.

In Comparative Example 1, it was confirmed that since the conductive particles did not aggregate, the low volume efficiency was large and there was a problem in connectivity. Although Comparative Example 2 showed low volume and low efficiency, it was confirmed that the TCT resistance was lowered as compared with Examples 1-8.

It was confirmed that Comparative Examples 3 and 4 have a large volume low efficiency, and the TCT resistance is significantly lowered in the initial conductivity and that they are insulated. Although Comparative Examples 5 and 6 had good adhesive strength and low volume efficiency, it was confirmed that short-circuiting occurred between the electrodes after the TCT resistant sample was prepared.

In Comparative Example 7, the adhesive strength was low and the TCT resistance was significantly reduced. Regarding Comparative Example 8, both the adhesive strength and the volume low efficiency were relatively good, but the TCT resistance was lowered.

In Comparative Example 9, the TCT resistance could not be measured because the substrate was largely warped and the connection portion was damaged when heated and connected at 260°C.

DESCRIPTION OF SYMBOLS 1... Connection structure, 2... Circuit board, 3... Electronic component, 4... Electronic component main body, 5... Base material, 6... Electronic component connection terminal, 7... Circuit board connection terminal, 8... Connection portion, 8a... Conductive part, 8b... Resin part, 10... Solder ball.

When applying the conductive adhesive composition for connecting the electrode pads that are downsized or the electrodes that are arranged at a narrow pitch, the short circuit due to the bridge between the electrodes is prevented, and sufficient conduction is achieved with a small amount of application. In order to realize it, it is effective to some extent to reduce the size of the conductive particles in the conductive adhesive composition.

One aspect of the present invention provides a conductive adhesive composition containing (A) conductive particles, (B) thermosetting resin, (C) flux activator, and (D) curing catalyst. The conductive particles include a metal having a melting point of 200° C. or lower. The average particle diameter of the conductive particles is 0.01~10μ m. The flux activator includes a compound having a hydroxyl group and a carboxyl group. The conductive adhesive composition is used to electrically connect a circuit board and an electronic component mounted on the circuit board. In other words, one aspect of the present invention is an application of the conductive adhesive composition for electrically connecting a circuit board and an electronic component mounted on the circuit board, or the conductive adhesive composition. The present invention relates to an application for manufacturing a connection structure having a circuit board and electronic components mounted on the circuit board.

The conductive adhesive composition according to the present invention is for electrically connecting a circuit board and an electronic component mounted on the circuit board while containing conductive particles containing a metal and having an average particle size of 10 μm or less. When used, it is possible to further improve the adhesive strength and the conductivity while suppressing the short circuit between the electrodes. For example, even if the conductive particles have a small particle size, good conductivity can be provided without lowering the melting property. Further, there is provided a conductive adhesive composition that forms a good connection state without short-circuiting while separating electrodes (connection terminals) arranged at a narrow pitch without bridging.

The thermosetting resin may include an epoxy resin.

Another aspect of the present invention is a circuit board having a base material and two or more connection terminals provided on the main surface of the base material, and two or more connection terminals facing the two or more connection terminals of the circuit board. There is provided a connection structure including: an electronic component having: and a connection portion that is disposed between the circuit board and the electronic component and that joins them. The connecting portion includes a conductive portion that is arranged between the connecting terminal of the circuit board and the connecting terminal of the electronic component and electrically connects them, and the conductive portion is the conductive adhesive according to the present invention. The conductive particles included in the composition are included. The connection portion may further include a resin portion provided around the conductive portion. The electronic component may include at least one selected from the group consisting of a driver IC, a module component incorporating a sensor element, a Schottky barrier diode, and a thermoelectric conversion element. The substrate may be a flexible substrate.

The average particle size of the conductive particles may be 0.01 to 10 μm. When the average particle size is 0.01 μm or more, the viscosity of the conductive adhesive composition does not become too high, so that workability tends to be improved, and the amount of the metal oxide film formed on the surface of the conductive particles. Is suppressed, and the conductive particles are thereby easily melted, so that the desired connected state tends to be easily maintained. When the average particle diameter of the conductive particles is 10 μm or less, there is a reduced possibility that adjacent electrodes may bridge and short-circuit between electrodes when connecting the electrodes arranged at a narrow pitch and the electronic component. When the conductive adhesive composition is applied, it tends to be difficult to apply a small amount to an electrode pad having a small area by any of the printing method, the transfer method and the dispensing method. From the viewpoint of further improving the coatability and workability of the conductive adhesive composition, the average particle size of the conductive particles may be 0.1 to 10 μm or 0.1 to 8 μm. In particular, from the viewpoint of improving the storage stability of the conductive adhesive composition and the mounting reliability of the cured product, the average particle size of the conductive particles may be 1 to 5 μm. Here, the average particle diameter of the conductive particles is a value obtained by a laser diffraction/scattering method.

The epoxy resin is not particularly limited as long as it is a compound having two or more epoxy groups in its molecule. Examples of the epoxy resin include bisphenol A, bisphenol F, and epoxy resins derived from such a Epikurorohido phosphorus bisphenol AD.

The content of the flux activator is 0.5 to 50% by mass, 0.5 to 40% by mass, or 4. with respect to the mass of the conductive particles, from the viewpoint of more effectively exhibiting the above-described effects of the present invention. 0 to 8.5 may be mass% Tsu der. Further, the content of the flux activator may be 1 to 35% by mass from the viewpoint of storage stability and conductivity. When the content of the flux active agent is 0.5 mass% or more, the effect is not a small tendency of improving conductivity to fusible metal is increased. When the content of the flux activator is 50% by mass or less, storage stability and printability tend to be improved.

The (D) curing catalyst is a component that accelerates the curing of the (B) thermosetting resin. (D) The curing catalyst may be a compound having an imidazole group from the viewpoint of curability at a desired curing temperature, length of pot life, heat resistance of the cured product, and the like, and is an imidazole-based epoxy resin curing agent. May be. Commercially available imidazole-based epoxy resin curing agents include 2P4MHZ-PW (2-phenyl-4-methyl-5-hydroxymethylimidazole), 2PHZ-PW (2-phenyl-4,5-dihydroxymethylimidazole), C11Z-. CN (1-cyanoethyl-2-undecylimidazole), 2E4MZ-CN (1-cyanoethyl-2-ethyl-4-methylimidazole), 2PZ-CN (1-cyanoethyl-2-phenylimidazole), 2MZ-A (2 , 4-diamino-6- [2 '- methylimidazolyl- - (1')] - ethyl -s- triazine), 2E4MZ-A (2,4-diamino-6- [2'-ethyl-4 'methylimidazolyl - (1′)]-Ethyl-s-triazine), 2MAOK-PW (2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine isocyanuric acid adduct) (any Also manufactured by Shikoku Chemicals Co., Ltd., etc. are listed. These curing catalysts may be used alone or in combination of two or more.

From the viewpoint of storage stability and curing time, the conductive adhesive composition may not contain a curing agent substantially. The term "substantially free from" means that the content is 0.05% by mass or less based on the total mass of the conductive adhesive composition.

In the conductive adhesive composition, from the viewpoint of more effectively exhibiting the above effects, the compounding ratio of the component (hereinafter referred to as the adhesive component) other than the (A) conductive particles to the (A) conductive particles (the adhesive component). The mass ratio of the conductive particles may be 5/95 to 50/50 when the total of these particles is 100. From the viewpoint of adhesiveness, conductivity, and workability, the compounding ratio may be 10/90 to 30/70. When the blending ratio is 5/95 or more, the viscosity of the conductive adhesive composition does not become too high, so that workability tends to be ensured, and the effect of improving the adhesiveness tends to increase. If the mixing ratio is 50/50 or less , the effect of improving the conductivity tends to be large.

According to the conductive adhesive composition of the present embodiment described above, it is possible to provide a mounted component to a circuit board having a small area electrode pad or electrodes arranged at a narrow pitch without causing a short circuit between the electrodes. It is possible to connect with various conductivity. The conductive adhesive composition of the present embodiment can lower the reflow heating temperature in the step of mounting an electronic component on a circuit board having electrodes arranged at a narrow pitch. When the temperature is lowered, the warp of the circuit board can be suppressed. The connection part formed by the conductive adhesive composition of the present embodiment can have a conductive part containing conductive particles and a resin part formed of an insulating adhesive component. Reinforcement with the resin portion can contribute to improving the temperature cycle test resistance of the connection structure.

In these connection structures, the conductive portion 8a is reinforced by the resin portion 8b. When the connection structure is subjected to heat history due to the temperature cycle test, a large amount of strain is applied to the connection portion and other constituent members due to warpage and the like. Since the conductive portion 8a is reinforced by the resin portion 8b, the deformation of the substrate is stemmed by the resin portion 8 b, generation of cracks can be suppressed in the connecting portion.

Examples 1 to 9 all showed good adhesive strength, volume resistivity , and TCT resistance. Almost no warp of the test substrate was observed.

In Comparative Example 1, it was confirmed that since the conductive particles did not aggregate, the volume resistivity was large and there was a problem in connectivity. Although Comparative Example 2 shows a low volume resistivity, resistance TCT resistance was confirmed to be reduced compared to Examples 1-8.

It was confirmed that Comparative Examples 3 and 4 had a large volume resistivity , and in terms of TCT resistance, the initial conductivity was remarkably lowered and they were insulated. Comparative Examples 5 and 6 were good in adhesive strength and volume resistivity , but it was confirmed that short-circuiting occurred between the electrodes after the TCT resistant sample was prepared.

In Comparative Example 7, the adhesive strength was low and the TCT resistance was significantly reduced. In Comparative Example 8, both the adhesive strength and the volume resistivity were relatively good, but the TCT resistance decreased.

Claims (12)

Contains (A) conductive particles, (B) thermosetting resin, (C) flux activator, and (D) curing catalyst,
The conductive particles include a metal having a melting point of 200° C. or less,
The average particle diameter of the conductive particles is 0.01 to 10 μm,
The flux activator contains a compound having a hydroxyl group and a carboxyl group,
A conductive adhesive composition used for electrically connecting a circuit board and an electronic component mounted on the circuit board. The conductive adhesive composition according to claim 1, wherein the content of the flux activator is 4.0 to 8.5 mass% with respect to the mass of the conductive particles. The conductive adhesive composition according to claim 1, wherein the metal having a melting point of 200° C. or lower contained in the conductive particles contains at least one selected from bismuth, indium, tin and zinc. The conductive adhesive composition according to claim 1, wherein the specific surface area of the conductive particles is 0.060 to 90 m ² /g. The conductive adhesive composition according to claim 1, wherein the thermosetting resin contains an epoxy resin. The conductive adhesive composition according to any one of claims 1 to 5, wherein the conductive adhesive composition is in a paste form at 25°C. The circuit board has a base material and two or more connection terminals arranged on the main surface of the base material, and is used for electrically connecting the two or more connection terminals and the connection terminals of the electronic component. The conductive adhesive composition according to any one of claims 1 to 6. The conductive adhesive composition according to claim 7, wherein the two or more connection terminals of the circuit board are arranged on the main surface of the base material at intervals of 200 μm or less from each other. A circuit board having a base material and two or more connection terminals provided on the main surface of the base material;
An electronic component having two or more connection terminals facing the two or more connection terminals of the circuit board;
A connection portion arranged between the circuit board and the electronic component, and joining them,
Equipped with
The connection portion is arranged between the connection terminal of the circuit board and the connection terminal of the electronic component, and includes a conductive portion electrically connecting them.
A connection structure, wherein the conductive portion contains the conductive particles contained in the conductive adhesive composition according to any one of claims 1 to 6. The connection structure according to claim 9, wherein the connection portion further includes a resin portion formed around the conductive portion. The connection structure according to claim 9, wherein the electronic component includes at least one selected from the group consisting of a driver IC, a module component containing a sensor element, a Schottky barrier diode, and a thermoelectric conversion element. The connection structure according to claim 9, wherein the base material is a flexible base material.

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