WO2019013336A1

WO2019013336A1 - Electroconductive adhesive composition and connection structure using same

Info

Publication number: WO2019013336A1
Application number: PCT/JP2018/026548
Authority: WO
Inventors: 振一郎須方; 精吾横地
Original assignee: 日立化成株式会社
Priority date: 2017-07-14
Filing date: 2018-07-13
Publication date: 2019-01-17
Also published as: KR20200030500A; JPWO2019013336A1; JP7331693B2; TW201908445A

Abstract

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

Description

Conductive adhesive composition and connection structure using the same

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

In recent years, with the downsizing and thinning of electronic devices, and the high integration of electronic components, the area reduction of electrode pad sizes arranged on electronic components and circuit boards and the narrowing of pitch between electrode pads have been promoted. It is required to mount electronic components at high density on such fine wiring patterns of electronic devices. Therefore, there is proposed a connecting material capable of connecting the substrate and the electronic component without causing a short between the electrodes when the electronic component is mounted on the substrate having the electrodes arranged at a narrow pitch. (See Patent Document 1).

However, when the electrode pad size is further reduced while the pitch between the electrodes is further narrowed, in the case of using a conventional connection material, a short circuit between the electrodes is caused to cause a conduction failure. . In addition, along with the thinning of the electronic device, the warping becomes apparent due to the heat history at the time of heating connection, and the reduction thereof is also a major issue. Therefore, there is a demand for a bonding method and a connecting material that have both narrow pitch connectivity and warpage resistance.

In order to mount an electronic component on a circuit board or the like, a bonding method using Sn-Ag-Cu solder or the like which is a lead-free solder is widely known. However, in the Sn—Ag—Cu solder, the connection temperature is as high as 260 ° C., and when the thickness of the electronic device is reduced, there is a problem that the warp significantly increases due to the heat history. Also, in order to reduce warpage, Sn—Bi solder having a melting point of 138 ° C. is also used as a lead-free solder that can be connected at a lower temperature. However, while the warpage of the substrate can be reduced by the connection method using the Sn—Bi solder, the brittleness of the Sn—Bi solder itself causes a problem that the metal joint is broken during the temperature cycle test to cause conduction failure.

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 type conductive adhesive can improve the temperature cycle test resistance by using a thermosetting resin as a binder component.

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

When applying a conductive adhesive composition for connection of electrodes of a small size or electrodes arranged at a narrow pitch, prevention of short circuit by inter electrode bridge and sufficient conduction with a small amount of application In order to realize it, it is effective to reduce the size of the conductive particles in the conductive adhesive composition to some extent.

However, in the case of conductive particles having an average particle diameter of 10 μm or less, the large specific surface area tends to increase the amount of the oxide film formed on the surface, thereby significantly lowering the meltability and the bondability. When the meltability and the bondability decrease, the conductivity of the conductive adhesive decreases. In addition, 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. There is a tendency for the decrease in adhesive strength after curing to be apparent.

The present invention has been made in view of the above circumstances, and includes a conductive particle having an average particle diameter of 10 μm or less containing a metal, and electrically connecting a circuit board and an electronic component mounted on the circuit board. Another object of the present invention is to provide a conductive adhesive composition to be used for the purpose of suppressing a short between electrodes and further improving adhesion strength and conductivity.

One aspect of the present invention provides a conductive adhesive composition comprising (A) conductive particles, (B) thermosetting resin, (C) flux activator, and (D) curing catalyst. The conductive particles contain a metal having a melting point of 200 ° C. or less. The conductive particles are particles having an average particle size of 0.01 to 10 μm. The flux activator includes a compound having a hydroxyl group and a carboxyl group. The said conductive adhesive composition is used in order to electrically connect a circuit board and the electronic component mounted in this 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 an electronic component 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 having an average particle diameter of 10 μm or less containing metal. When used, it is possible to further improve the adhesive strength and the conductivity while suppressing a short between the electrodes. For example, even if the conductive particles have a small particle size, good conductivity can be provided without deterioration in meltability. Furthermore, a conductive adhesive composition is provided which forms a good connection without shorting while separating the electrodes (connection terminals) arranged at a narrow pitch without bridging.

The content of the flux activator may be 4.0 to 8.5% by 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 contain an epoxy resin.

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

The conductive adhesive composition has a circuit board having a substrate and two or more connection terminals arranged on the main surface of the substrate, and electrically connects the two or more connection terminals and the connection terminals of the electronic component. May be used to connect. In this case, two or more connection terminals of the circuit board may be arranged on the main surface of the base at an interval of 200 μm or less.

Another aspect of the present invention is a circuit board having a substrate and two or more connection terminals provided on the main surface of the substrate, and two or more connection terminals facing the two or more connection terminals of the circuit board And a connection portion disposed between the circuit board and the electronic component and connecting the same. The connection portion includes a conductive portion disposed between the connection terminal of the circuit board and the connection terminal of the electronic substrate and electrically connecting them, and the conductive portion is the conductive adhesive according to the present invention. The conductive particles contained 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 to electrically connect a circuit board and an electronic component mounted on the circuit board while including conductive particles having an average particle diameter of 10 μm or less containing metal. When it is done, 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 and suppressing warpage of small and thin devices in the process of mounting an electronic component on a circuit board. The conductive adhesive composition according to the present invention is also suitable for the connection of fine connection terminals by a small amount of application since it tends to have a low viscosity.

A connection structure having a connection formed by the conductive adhesive composition is excellent not only in resistance to stretching and bending but also in resistance to temperature cycle tests.

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.

(A) The conductive particles contain a metal having a melting point of 200 ° C. or less. The melting point of the metal contained in the conductive particles may be 180 ° C. or less, or 150 ° C. or less. 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, they are considered to melt and aggregate at a relatively low temperature, and the aggregates contribute to the electrical connection of the connection terminal. 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 environmental load. The metal contained in the conductive particles is, for example, one metal single substance selected from tin (Sn), bismuth (Bi), indium (In), zinc (Zn) or the like, or two or more selected from these. Alloys containing metal species are mentioned. The alloy can be platinum (Pt), gold (Au), silver (Ag), and the like within the range in which the melting point of the whole metal in the conductive particles is 200 ° C. or less from the viewpoint of obtaining better connection reliability. It may further contain a high melting point component selected from copper (Cu), nickel (Ni), palladium (Pd), aluminum (Al) and the like.

Specific examples of metals constituting 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 -Cu0.5-Bi7.5 solder (melting point 189 ° C), Sn96-Zn8-Bi3 solder (melting point 190 ° C), Sn91-Zn9 solder (melting point 197 ° C) and the like. They show a definite melting behavior after melting. The solidification behavior means that the metal cools and hardens after melting. Among these, Sn42-Bi58 solder may be used from the viewpoint of availability and effects. These are used individually or in combination of 2 or more types.

The average particle size of the conductive particles may be 0.01 to 10 μm. If the average particle diameter is 0.01 μm or more, the viscosity of the conductive adhesive composition does not become too high, and the workability tends to be improved, and the amount of the metal oxide film formed on the surface of the conductive particles As a result, the conductive particles tend to be melted, which tends to maintain the desired connection state. When the average particle diameter of the conductive particles is 10 μm or less, adjacent electrodes are bridged and the possibility of a short circuit between the electrodes decreases when the electrodes and the electronic component are connected at the narrow pitch. When the conductive adhesive composition is applied, a small amount of application tends to be difficult to the small area electrode pad by any of the printing method, the transfer method and the dispensing method. The average particle diameter of the conductive particles may be 0.1 to 10 μm or 0.1 to 8 μm from the viewpoint of further improving the coatability and the workability of the conductive adhesive composition. 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 diameter of the conductive particles may be 1 to 5 μm. Here, the average particle diameter of the conductive particles is a value determined 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 of only a metal, or cover core particles made of a solid material other than metal such as ceramics, silica, resin material, etc. and the surface of the core particles, and the melting point is 200 ° C. It may be a composite particle having a metal film made of the following metal, or may be a combination of a metal particle and a composite particle.

The content of the conductive particles may be 5 to 95% by mass based on 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 is lowered, so that the workability tends to be improved, and the adhesive in the conductive adhesive composition relatively. There is a tendency for the mounting reliability of the cured product to be improved because the amount of components is increased. The content of the conductive particles may be 10 to 90% by mass from the viewpoint of improving workability or conductivity, and from the viewpoint of enhancing the mounting reliability of the cured product of the conductive adhesive composition, 85 mass% may be sufficient. Here, when a conductive adhesive composition contains the below-mentioned diluent, content of each component is defined on the basis of the mass of components other than a diluent. Diluents here mean components, such as organic solvents other than the below-mentioned reactive diluent.

The conductive adhesive composition may further include (a1) high melting point conductive particles containing a metal having a melting point exceeding 200 ° C., in addition to the conductive particles containing a metal having a melting point of 200 ° C. or less. As a metal whose melting | fusing point is higher than 200 degreeC, the alloy which consists of 1 type of elemental metals single or 2 or more types of metal chosen from Pt, Au, Ag, Cu, Ni, Pd, Al etc. is mentioned, for example. 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 product of high melting point conductive particles, “MA05K” (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is silver-silver-copper powder, is available.

When combining (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 exceeding 200 ° C., 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 the function of adhering the adherend, and also acts as a binder component for bonding the conductive particles in the conductive adhesive composition and the filler added as needed. As such a thermosetting resin, thermosetting organic polymer compounds, such as an epoxy resin, (meth) acrylic resin, maleimide resin, and cyanate resin, and those precursors are mentioned, for example. Here, (meth) acrylic resin refers to methacrylic resin and acrylic resin. The thermosetting resin may be a compound having a polymerizable carbon-carbon double bond represented by (meth) acrylic resin and maleimide resin, or an epoxy resin. These thermosetting resins are excellent in heat resistance and adhesiveness, and can also be handled in a liquid state if they are dissolved or dispersed in an organic solvent as necessary, so they are also excellent in workability. An epoxy resin may be used from the viewpoint of availability and reliability. The above-mentioned thermosetting resin is used individually by 1 type or in combination of 2 or more types.

The epoxy resin is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule. As an epoxy resin, the epoxy resin etc. which are derived from bisphenol A, bisphenol F, bisphenol AD etc. and epichlorohydridon etc. are mentioned, for example.

Epoxy resins are commercially available. Specific examples thereof include bisphenol A type epoxy resin AER-X8501 (manufactured by Asahi Kasei Co., Ltd., trade name), R-301 (Mitsubishi Chemical Co., Ltd., trade name), YL-980 (Mitsubishi Chemical Co., Ltd., Trade name) YDF-170 (made by Tohto Kasei Co., Ltd., trade name) which is bisphenol F type epoxy resin, YL-983U (made by Mitsubishi Chemical Co., Ltd., trade name), R-1710 (bisphenol AD type epoxy resin) Mitsui Chemicals, Inc., trade name) Phenolic novolac epoxy resin N-730S (DIC, trade name), Quatrex-2010 (Dow Chemical, trade name), cresol novolac epoxy resin YDCN-702S (made by Nippon Steel & Sumikin Chemical Co., Ltd., product name), EOCN-10 (Nippon Kayaku Co., Ltd., trade name), multifunctional epoxy resin EPPN-501 (Nippon Kayaku Co., Ltd., trade name), TACTIX-742 (Dow Chemical Co., Ltd. trade name), VG-3010 (Mitsui Chemical Co., Ltd., trade name), 1032S (Mitsubishi Chemical Co., Ltd., trade name), HP-4032 (an epoxy resin having a naphthalene skeleton) (trade name, DIC Corporation), alicyclic epoxy resin Certain EHPE-3150, CEL-3000 (both made by Daicel, trade name), DME-100 (made by Shin Nippon Rika Co., Ltd., trade name), EX-216L (made by Nagase Chemical Industries, Ltd., trade name), fat Family epoxy resin W-100 (Shin Nippon Rika Co., Ltd., trade name), amine type epoxy resin ELM-100 (Sumitomo Chemical Co., Ltd. trade name) YH-434L (trade name of Nippon Steel Sumikin Chemical Co., Ltd.), TETRAD-X, TETRAD-C (both trade name of Mitsubishi Gas Chemical Co., Ltd.), 630, 630LSD (both trade name of Mitsubishi Chemical Co., Ltd.) 1, Resorcinol type epoxy resin Denacol EX-201 (made by Nagase Chemical Industry Co., Ltd., trade name), Neopentyl glycol type epoxy resin Denacol EX-211 (made by Nagase Chemical Industry Co., Ltd., trade name), 1, 6 -Hexanediol diglycidyl ether, Denacol EX-212 (Nagase Chemical Industries, Ltd., trade name), ethylene-propylene glycol type epoxy resin Denacol EX series (EX-810, 811, 850, 851, 851, 821, 830 , 832, 841, 861 (all are Nagase Chemical Industries, Ltd. shares Inc., trade name)), the following formula (epoxy resin E-XL-24 represented by I), E-XL-3L (both manufactured by Mitsui Chemicals, Inc., trade name). Among these epoxy resins, select at least one selected from bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AD epoxy resin, and amine epoxy resin, which have few ionic impurities and are excellent in reactivity. May be

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

The above-mentioned 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 (trade name, manufactured by Nippon Kayaku Co., Ltd.), PP-101 (trade name, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), ED-502, ED-509, ED-509S (made by ADEKA Co., Ltd.) , Trade name), YED-122 (Mitsubishi Chemical Co., Ltd., trade name), KBM-403 (Shin-Etsu Chemical Co., Ltd., trade name), TSL-8350, TSL-8355, TSL-9905 (Toshiba Silicone Co., Ltd.) Product names). These may be used alone or in combinations of two or more.

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

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

Examples of monoacrylate compounds 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, 2- Ethyl hexyl 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, methoxy diethylene glycol acrylate, methoxy polyethylene glycol acrylate, dicyclopentenyl oxyethyl acrylate, 2-phenoxyethyl acrylate, phenoxy diethylene glycol acrylate, phenoxy polyethylene Glycol acrylate, 2-benzoyloxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, benzyl acrylate, 2-cyanoethyl acrylate, γ-acryloxyethyltrimethoxysilane, glycidyl acrylate, tetrahydrofurfuryl acrylate, dimethylaminoethyl acrylate, Diethyla These include minoethyl acrylate, acryloxyethyl phosphate and acryloxyethyl phenyl acid phosphate.

Examples of monomethacrylate compounds 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, methoxy polyethylene glycol methacrylate, dicyclopentenyloxyethyl methacrylate, 2-phenoxyethyl methacrylate, phenoxy Diethylene glycol methacrylate, phenoxy polyethylene glycol methacrylate, 2-benzoyloxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, benzyl methacrylate, 2-cyanoethyl methacrylate, γ-methacryloxyethyl trimethoxysilane, glycidyl methacrylate And tetrahydrofurfuryl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methacryloxyethyl phosphate and methacryloxyethyl phenyl acid phosphate.

Examples of diacrylate compounds 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 1 mol of bisphenol AD and glycidyl acrylate 2 Moles of the reactant, bisphenol A, bisphenol F or bisphenol AD And diacrylates of bis (acryloxypropyl) polydimethylsiloxanes and bis (acryloxypropyl) methylsiloxane-dimethylsiloxane copolymers of diacrylates of bis (ethylene oxide) adducts, bisphenol A, bisphenol F, or poly (propylene oxide) adducts of bisphenol F or bisphenol AD. .

Examples of dimethacrylate compounds include ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,3-butanediol dimethacrylate, 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 1 mol of bisphenol AD and glycidyl methacrylate 2 Moles of reactant, bisphenol A, bisphenol F or Dimethacrylate of a polyethylene oxide adduct of scan phenol AD, polypropylene oxide adduct of bisphenol F or bisphenol AD, bis (methacryloxypropyl) polydimethylsiloxane, and bis (methacryloxypropyl) methylsiloxane - include dimethylsiloxane 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 polymerized in advance and then used, and these compounds are mixed with conductive particles, flux activators, etc., and polymerization is carried out simultaneously with mixing. May be The compound which has a carbon-carbon double bond which can be polymerized in these molecules is used individually by 1 type or in combination of 2 or more types.

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 a radical polymerization initiator, what is normally used can be used. Examples thereof include peroxides such as benzoyl peroxide and 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.

A commercially available thing can be used as (meth) acrylic resin. Specific examples thereof include FINEDIC A-261 (trade name, manufactured by DIC Corporation), FINEDIC A-229-30 (trade name, manufactured by DIC Corporation), 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. It is also good.

(C) The flux activator is a component that exhibits the function of removing the oxide film formed on the surface of the conductive particles. By using such a flux activator, the oxide film that hinders the melt 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 exhibits good flux activity and can exhibit reactivity with an epoxy resin that can be used as a thermosetting resin. The compound having a hydroxyl group and a carboxyl group may be an aliphatic dihydroxycarboxylic acid from the viewpoint of showing a good oxide film removing ability even if the particle size of the conductive particle is small and the amount of the oxide film is large. Specifically, the flux activator may contain a compound represented by the following general formula (V) or tartaric acid.

In formula (V), R 5 represents an alkyl group having 1 to 5 carbon atoms. From the viewpoint of exerting the above-mentioned effects according to the present invention more effectively, 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 exerting the above-mentioned effects according to the present invention more effectively, m may be 0 and n may be 1 or both m and n may be 1.

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

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

The curing catalyst (D) is a component that accelerates the curing of the thermosetting resin (B). The curing catalyst (D) may be a compound having an imidazole group from the viewpoint of the curing property at a desired curing temperature, the length of pot life, the heat resistance of a cured product, etc., and is an imidazole epoxy resin curing agent May be Commercially available imidazole-based epoxy resin curing agents include 2P4 MHZ-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'-methyl] Luimidazolyl- (1 ')]-ethyl-s-triazine isocyanuric acid adducts (all manufactured by Shikoku Kasei Kogyo Co., Ltd., trade names) 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 parts by mass or more, the curability tends to be improved. When the content of the curing catalyst is 90 parts by mass or less, the workability when handling the conductive adhesive composition tends to be improved.

The conductive adhesive composition contains, in addition to the above-mentioned components, if necessary, a flexibilizer for stress relaxation, a diluent for improving workability, an adhesive strength improver, a wettability improver, and a defoaming agent. It may also include one or more additives selected from the group consisting of agents. 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 adhesion. Examples of the silane coupling agent include Shin-Etsu Chemical Co., Ltd., trade name “KBM-573” 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 an antifoaming agent. The adhesion improver, the wettability improver, and the antifoaming agent may be used alone or in combination of two or more. The content thereof may be 0.1 to 10% by mass with respect to the total mass of the conductive adhesive composition.

As a flexible agent, liquid polybutadiene (made by Ube Industries, Ltd., trade name “CTBN-1300 × 31”, “CTBN-1300 × 9”, 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 can contain a diluent, if necessary, in order to improve the workability at the time of preparation of the paste composition and the application workability at the time of use. The diluent is a relatively high boiling organic solvent such as butyl carbitol, butyl carbitol acetate, butyl cellosolve, carbitol, butyl cellosolve acetate, carbitol acetate, dipropylene glycol monomethyl ether, ethylene glycol diethyl ether, α-terpineol, etc. May be The content of the diluent may be 0.1 to 30% by 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. These fillers may be used alone or in combination of two or more.

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 commercially available ones are available. Commercially available curing agents include, for example, phenol novolac resin H-1 (manufactured by Meiwa Kasei Co., Ltd., trade name), VR-9300 (Mitsui Chemical Co., Ltd., trade name), phenol aralkyl resin XL-225. (Mitsui Chemical Co., Ltd., trade name), MTPC (a Honshu Chemical Industry Co., Ltd., trade name) which is a p-cresol novolac resin represented by the following general formula (II), AL- which is an allylated phenol novolac resin Examples thereof include VR-9300 (trade name, manufactured by Mitsui Chemicals, Inc.) and PP-700-300 (trade name, manufactured by JXTG Energy Corp.) which is a special phenol resin represented by the following general formula (III).

In Formula (II), a plurality of R 1 '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 represents an integer of 2 to 4;

As the curing agent, those conventionally used as a curing agent such as dicyandiamide can be used, and commercially available products are available. As a commercial product, for example, dibasic acid dihydrazide represented by the following general formula (IV) ADH, PDH and SDH (all of which are manufactured by Nippon Finechem Co., Ltd., trade names), reaction products of epoxy resin and amine compound Novacua (Asahi Kasei Co., Ltd., trade name), which is a microcapsule type curing agent comprising These curing agents may be used alone or in combination of two or more.

In formula (IV), R 4 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 be substantially free of a curing agent. The phrase "does not substantially contain" 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 exhibiting the above effects more effectively, the compounding ratio of the component other than the (A) conductive particles to the (A) conductive particles (hereinafter referred to as an adhesive component) (adhesive component) The (electroconductive particles) may have a mass ratio of 5/95 to 50/50, where the total thereof is 100. From the viewpoint of adhesion, conductivity and workability, the above blending ratio may be 10/90 to 30/70. If the compounding ratio is 5/95 or more, the viscosity of the conductive adhesive composition does not become too high, so the workability tends to be easily ensured, and the effect of improving the adhesiveness tends to be large. When the blending ratio is 50/50 or more, the effect of improving the conductivity tends to be increased.

Each component demonstrated above may combine any of what was illustrated in each.

The conductive adhesive composition can be obtained by heating each of the above-described components at once or multiple times, if necessary, and mixing, dissolving, granulating or dispersing. The conductive adhesive composition may be in the form of a paste in which each component is uniformly dispersed. Examples of the dispersion / dissolution apparatus used at this time include a common stirrer, a mortar, a 3-roll mill, and a planetary mixer. The conductive adhesive composition may be in the form of a paste 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, the mounted component is excellent without causing a short between the electrodes with respect to the circuit board having the electrode pad of small area or the electrodes arranged at the narrow pitch. It is possible to connect by using different conductivity. The conductive adhesive composition of the present embodiment can lower the reflow heating temperature in the process of mounting the electronic component on the circuit board having the electrodes arranged at the sandwiching pitch. When the temperature is lowered, warpage of the circuit board can be suppressed. The connection part formed of 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. The reinforcement by the resin part can contribute to the improvement of the resistance to temperature cycle test 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 base 5 and a circuit board 2 having two or more connection terminals 7 formed on the main surface of the base 5, an electronic component 3 facing the circuit board 2, and a circuit It is an electronic component mounting substrate provided with the connection part 8 arrange | positioned between the board | substrate 2 and the electronic component 3, and joining these. The electronic component 3 has a main body 4 and two or more connection terminals 6. The connection part 8 is comprised from the electroconductive part 8a and the resin part 8b formed in the circumference | surroundings of the electroconductive part 8a. The connection portion 8 is disposed 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 portion 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 containing a thermosetting resin and a curing catalyst which is contained in the conductive adhesive composition. However, the resin portion 8b may contain a small amount of conductive particles as long as the appropriate insulation property is maintained. The circuit board 2 and the electronic component 3 are mutually joined and electrically connected by the connecting portion 8.

The connection structure 1 prepares, for example, the circuit board 2 and the electronic component 3 each having two or

more connection terminals

7 and 6, and conductively adheres on the connection terminals 7 of the circuit board 2 or the connection terminals 6 of the electronic component 3. Component on the circuit board 2 so that the connection terminal 7 of the circuit board 2 and the connection terminal 6 of the electronic component 3 face each other through the step of applying the agent composition and the applied conductive adhesive composition 3 and disposing the circuit board 2, the conductive adhesive composition, and the electronic component 3 in a temporary connecting body, and heating the temporary connecting body to cure the conductive adhesive composition. A conductive portion 8a is formed to electrically connect the connection terminal 7 of the circuit board 2 and the connection terminal 6 of the electronic component 3 including conductive particles in the conductive adhesive composition, thereby including the conductive portion 8a. The circuit board 2 and the electronic component 3 are joined by the connecting portion 8 It is by a method comprising the step of obtaining the connection structure has, can be produced.

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

In the case of the connection structure 1 shown in FIG. 2, a conductive portion 8 a formed of a conductive adhesive composition and a solder ball 10 are provided. The solder ball 10 is provided on the connection terminal 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 through the conductive portion 8 a and the solder ball 10. The connection terminals 7 of the circuit board 2 may be arranged on the main surface of the substrate 5 at an interval of 200 μm or less.

In these connection structures, the conductive portion 8a is reinforced by the resin portion 8b. When the connection structure receives a thermal history by a temperature cycle test, the connection and other components are greatly distorted due to the occurrence of 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 occurrence of cracks in the connection portion is suppressed.

When the cross section along the thickness direction of the connection structure is viewed at a 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.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. The present invention can be variously modified without departing from the scope of the invention.

For example, if the circuit substrate is a support substrate for mounting an LED and the electronic component is an LED element, the connection for bonding and electrically connecting the support substrate for mounting an LED, the LED element, and the support substrate and the LED element An LED device is provided. The connection portion is a cured product of the conductive adhesive composition. The support substrate for mounting the LED and the LED element are not particularly limited.

If the circuit substrate is a support substrate for mounting a sensor element and the electronic component is a sensor element, the support substrate for mounting a sensor element, the sensor element, and a connection for bonding and electrically connecting the support substrate and the sensor element And a module including the sensor element. The connection portion is a cured product of the conductive adhesive composition. The support substrate and the sensor element for mounting 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 by way of examples, but the present invention is not limited to these examples. The materials used in the examples and comparative examples are those manufactured or obtained by the following method.

Example 1
17.7 parts by mass of YL 980 (Mitsubishi Chemical Co., Ltd., trade name of bisphenol F type epoxy resin), 0.9 parts by mass of 2P4 MHZ-PW (trade name of imidazole compound, manufactured by Shikoku Kasei Kogyo Co., Ltd.), An adhesive component was prepared by mixing 6.4 parts by weight of BHPA (2,2-bis (hydroxymethyl) propionic acid) as an agent and passing the mixture three times through a three-roll.

Next, to 20 parts by mass of the adhesive component, 75 parts by mass of conductive particles Sn42-Bi58 particles (average particle diameter 5 μm, manufactured by Mitsui Metal Mining Co., Ltd., melting point: 138 ° C.) are added, and the obtained mixture is obtained The conductive adhesive composition was obtained by stirring using a planetary mixer and defoaming treatment at 500 Pa or less for 10 minutes.

[Examples 2 to 9, Comparative Examples 1 to 9]
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 compositions shown in Table 1 were changed. The following commercially available conductive adhesives were used in Comparative Examples 7-9.
<Conductive particles>
Sn42-Bi58 solder particles (Mitsui Metal Mining Co., Ltd., melting point 138 ° C)
Sn42-Bi58 10 μm particles: average particle diameter 10 μm
Sn42-Bi58 10 to 25 μm particles: average particle diameter of more than 10 μm to 25 μm or less Sn42-Bi58 20 to 38 μm particles: average particle diameter of 20 to 38 μm
Sn42-Bi57-Ag1 solder particles (Mitsui Metal Mining Co., Ltd., melting point 139 ° C)
Sn42-Bi57-Ag1 5 μm particles: average particle diameter 5 μm
<Flux activator>
BHBA: 2,2-bishydroxymethylbutanoic acid glutaric acid tartaric acid adipic acid <other conductive adhesive>
Ag paste: made by Fujikura Kasei Co., Ltd., Doatite (trade name)
Sn42-Bi58 cream solder: made by Senju Metal Industry Co., Ltd., Eco solder (trade name)
Sn96.5-Ag3-Cu0.5 cream solder: manufactured by Senju Metal Industry Co., Ltd., Eco solder (trade name)

(Evaluation of adhesion, conductivity, TCT resistance)
The properties of the conductive adhesive compositions according to Examples 1 to 9 and Comparative Examples 1 to 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 onto a silver-plated copper plate, and a rectangular flat plate-like tin-plated copper plate of 2 mm × 2 mm × 0.25 mm was crimped thereon to obtain a test piece. Thereafter, a heat history of 150 ° C. for 10 minutes was added to the test pieces according to Examples 1 to 9 and Comparative Examples 1 to 8. A heat history of 260 ° C. for 10 minutes was added to the test piece of Comparative Example 9. The adhesive strength (shear strength) at 25 ° C. of each test piece after the thermal history was added was measured using a bond tester (manufactured by DAGE, 2400) under the conditions of a shear speed of 500 μm / sec and a clearance of 100 μm.

(2) Conductivity (volume resistivity)
Two strip-like gold-plated copper plates of 1 mm × 50 mm × 0.03 mm were pasted via the above-mentioned conductive adhesive composition so as to be orthogonal to each other to obtain a test piece. The dimensions of the layer of adhesive in the orthogonal part of the copper plate were 1 mm x 1 mm x 0.03 mm. Subsequently, the same heat history as in (1) above was added to the test piece. The volume resistivity of the subsequent test pieces was measured by the four probe method.

(3) TCT resistance 100 mm × 50 mm × 0.5 mm rectangular flat thin FR4 provided with two adjacent copper foil lands (0.2 mm × 0.4 mm) and the distance between the copper foil lands is 100 μm The substrate was prepared. Next, the conductive adhesive composition was printed on a copper foil land using a metal mask (thickness 100 μm, opening size 0.2 mm × 0.3 mm). A small chip resistance (0.2 mm × 0.4 mm) having an inter-electrode distance of 100 μm was placed thereon so that the electrode and the copper foil land face each other via the conductive adhesive composition. The same heat history as the above (1) was added to the obtained component mounting substrate to obtain a test substrate for TCT resistance evaluation. The initial resistance of this test substrate was confirmed using a simple tester. Thereafter, the test substrate is held at -55 ° C for 30 minutes, heated to 125 ° C for 5 minutes, held at 125 ° C for 30 minutes, and lowered to -55 ° C for 5 minutes in this order using a thermal shock tester. The sample was subjected to a thermal shock test in which temperature change is regarded as one cycle. The connection resistance of the test substrate 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 up to the point at which the rate of change in resistance was within ± 10% of the initial resistance was used as an index of TCT resistance. In the table, "initially open" means that the initial conductivity was extremely low. "Initial short" means that a short occurred before the thermal shock test.

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

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

It was confirmed that Comparative Examples 3 and 4 have a large volume low efficiency, and the TCT resistance is significantly reduced in initial conductivity and insulated. Although the adhesive strength and volume low efficiency were favorable for Comparative Examples 5 and 6, it was confirmed that the electrodes were short-circuited after the preparation of the TCT resistant sample.

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

In Comparative Example 9, when the heating connection was performed at 260 ° C., the substrate was largely warped, and the connection portion was broken, so that the TCT resistance could not be measured.

DESCRIPTION OF SYMBOLS 1 ... connection structure, 2 ... circuit board, 3 ... electronic component, 4 ... main part of electronic component, 5 ... base material, 6 ... connection terminal of electronic component, 7 ... connection terminal of circuit board, 8 ... connection portion, 8a: conductive part, 8b: resin part, 10: solder ball.

Claims

(A) conductive particles, (B) thermosetting resin, (C) flux activator, and (D) curing catalyst,
The conductive particles contain 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 includes a compound having a hydroxyl group and a carboxyl group,
A conductive adhesive composition used to electrically connect 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% by 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 less contained in the conductive particles contains at least one selected from bismuth, indium, tin and zinc.
The conductive adhesive composition according to any one of claims 1 to 3, wherein the specific surface area of the conductive particles is 0.060 to 90 m 2 / g.
The conductive adhesive composition according to any one of claims 1 to 4, wherein the thermosetting resin comprises an epoxy resin.
The conductive adhesive composition according to any one of claims 1 to 5, wherein the conductive adhesive composition is in the form of a paste at 25 属 C.
The circuit board has a base and two or more connection terminals disposed on the main surface of the base, and is used to electrically connect the two or more connection terminals to the connection terminals of the electronic component. The conductive adhesive composition according to any one of claims 1 to 6, which is
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 at an interval of 200 μm or less.
A circuit board having a substrate and two or more connection terminals provided on the main surface of the substrate;
An electronic component having two or more connection terminals facing the two or more connection terminals of the circuit board;
A connection portion disposed between the circuit board and the electronic component and joining them;
Equipped with
The connection portion includes a conductive portion which is disposed between the connection terminal of the circuit board and the connection terminal of the electronic component and electrically connects them.
A connected structure, wherein the conductive portion includes 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 incorporating a sensor element, a Schottky barrier diode, and a thermoelectric conversion element.
The connection structure according to any one of claims 9 to 11, wherein the substrate is a flexible substrate.