JP6782413B2 - Flexible wiring board with conductive adhesive composition, connection structure and semiconductor light emitting element - Google Patents

Description

The present invention relates to a conductive adhesive composition used for electrically connecting a flexible wiring board and an electronic component, a connection structure using the adhesive composition, and a flexible wiring board on which a semiconductor light emitting element is mounted.

In recent years, flexible electronics and stretchable electronics, which manufacture devices using a flexible and highly elastic circuit board, are expected as a manufacturing technology for highly convenient and versatile devices such as wearable devices. In such a field, since a large mechanical load is applied to the circuit board used, a stretchable board and a circuit pattern having high elasticity and flexibility have been proposed (see Patent Documents 1 to 3).

However, when an electronic component is mounted on a flexible and highly elastic circuit board to manufacture a device, the electronic component itself does not have elasticity and flexibility. Therefore, when the device is used, the connection portion between the substrate and the electronic component is used. The problem is that large distortions occur and the connections and electronic components are destroyed. Further, an organic base material having thermoplasticity is often used for the stretchable substrate, and it is also a big problem that the substrate is deformed due to the thermal history at the time of mounting electronic components. Therefore, in this field, a connection method capable of forming a connection portion having sufficient elasticity and bending resistance with respect to an elastic substrate and reducing damage to the substrate as much as possible when mounting electronic components. Is required.

In order to mount electronic components on a circuit board or the like, a connection method using Sn-Ag-Cu solder or the like, which is a lead-free solder, is widely known. However, Sn-Ag-Cu solder has a high connection temperature of 260 ° C., and when an organic substrate having thermoplasticity, which is promising as a circuit board for wearable devices, is used, electronic components are mounted on the substrate. There is a problem that the thermal history in the reflow process causes thermal shrinkage and deformation of the substrate, and the flexibility and elasticity of the substrate are significantly reduced.

Further, as a lead-free solder that can be connected at a lower temperature, Sn—Bi solder having a melting point of 138 ° C. is also used. However, although the connection method using Sn-Bi solder can reduce the damage to the substrate, there is a problem that a great deal of stress is concentrated on the solder connection portion due to expansion and contraction and bending of the circuit board, the connection portion is destroyed, and conduction is poor. There is.

In order to overcome these problems, a conductive adhesive in which metal particles such as silver powder are dispersed in a thermosetting resin to form a paste has been proposed (see Patent Document 4). The thermosetting type conductive adhesive can improve the temperature cycle test resistance (TCT resistance) by using a thermosetting resin as a binder component.

Japanese Unexamined Patent Publication No. 2014-162124 Japanese Unexamined Patent Publication No. 2014-162125 JP-A-2015-079803 Japanese Unexamined Patent Publication No. 2002-161259

However, since the mechanism for developing conductivity in the conductive adhesive described in Patent Document 4 is due to contact between metals, it is necessary to increase the content of conductive particles in order to ensure good conductivity. As a result, as the binder component decreases, the adhesive strength of the adhesive decreases, and when applied to a flexible circuit board that is used while repeating expansion and contraction and bending, the adhesive strength and conductivity are significantly reduced. It tends to end up.

Therefore, the present invention has been made in view of the above circumstances, and it is possible to form a cured product having excellent adhesive strength and conductivity even if expansion and contraction and bending are repeated, and the flexible wiring board and the electronic component are electrically connected. It is an object of the present invention to provide a conductive adhesive composition used for specifically connecting, a connection structure using the conductive adhesive composition, and a flexible wiring board on which a semiconductor light emitting element is mounted.

The present invention is a conductive adhesive composition used for electrically connecting a flexible wiring board and an electronic component, which is a conductive particle containing a metal having a melting point of 200 ° C. or lower, a thermosetting resin, and a flux. Provided is a conductive adhesive composition containing an activator and a curing catalyst.

The flux activator may contain a compound having a hydroxyl group and a carboxyl group. Further, the metal contained in the conductive particles may contain at least one selected from the group consisting of bismuth, indium, tin and zinc. Further, the thermosetting resin may contain an epoxy resin.

The conductive adhesive composition according to the present invention may be a paste-like composition having a viscosity at 25 ° C. of 5 to 400 Pa · s.

The conductive adhesive composition according to the present invention may be used to electrically connect a connection terminal arranged on a flexible wiring board and a connection terminal arranged on an electronic component. The flexible wiring board may be composed of a base material having flexibility and elasticity.

The flexible wiring substrate may be composed of a substrate containing at least one selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, polyethylene naphthalate, polyketone, polyetheretherketone, thermoplastic polyurethane elastomer and cycloolefin polymer. ..

The present invention also includes a flexible wiring board having a first connection terminal, an electronic component having a second connection terminal, and a connection portion arranged between the flexible wiring board and the electronic component. Provided is a connection structure containing a cured product of the conductive adhesive composition according to the present invention, in which a first connection terminal and a second connection terminal are electrically connected.

The connection portion may have a connection structure including a metal portion containing a metal having a melting point of 200 ° C. or lower and a resin portion containing a thermosetting resin.

In the connection structure according to the present invention, when the connection structure is viewed in a cross section orthogonal to the upper surface of the second connection terminal, the metal portion is in contact with the second connection terminal and the first connection terminal, and the resin portion is It may have a connection structure existing around the metal part.

The area ratio of the metal part to the resin part may be 5:95 to 80:20. Further, a sealing member may be further provided around the resin portion.

The electronic component may include at least one selected from the group consisting of semiconductor light emitting elements, capacitors, Schottky barrier diodes and driver integrated circuits.

The present invention further includes a flexible wiring board having a first connection terminal, a semiconductor light emitting element having a second connection terminal, and a connection part arranged between the flexible wiring board and the semiconductor light emitting element, and is a connection part. However, there is provided a flexible wiring substrate on which a semiconductor light emitting element is mounted, which contains a cured product of the conductive adhesive composition according to the present invention, and the first connection terminal and the second connection terminal are electrically connected. ..

According to the present invention, a cured product having good adhesive strength and conductivity can be formed even if expansion and contraction and bending are repeated, and the conductivity used for electrically connecting a flexible wiring board and an electronic component. Adhesive compositions can be provided. According to the present invention, a connection structure including a connecting portion containing a cured product of the conductive adhesive composition and having excellent adhesive strength and conductivity even after repeated expansion and contraction and bending, and a flexible wiring on which a semiconductor light emitting element is mounted. A substrate can be provided.

Further, the conductive adhesive composition according to the present invention can lower the mounting temperature (for example, reflow heating temperature) in the mounting process of the flexible wiring board and the electronic component, so that the flexibility and elasticity of the substrate can be lowered. It is possible to manufacture a connection structure such as a flexible wiring board on which electronic components are mounted without damaging the above. Further, in the conductive adhesive composition according to the present invention, since the connecting portion having a connecting structure in which the metal portion and the resin portion are separated can be formed, the connecting portion is reinforced, and only bending resistance and stretch resistance are obtained. In addition, a connection structure having excellent TCT resistance can be produced.

It is a schematic cross-sectional view which shows one Embodiment of the electronic component mounting flexible wiring board which concerns on this invention. It is a schematic cross-sectional view which shows one Embodiment of the electronic component mounting flexible wiring board which concerns on this invention. It is a schematic cross-sectional view which shows one Embodiment of the electronic component mounting flexible wiring board which concerns on this invention.

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

<Conductive adhesive composition>
The conductive adhesive composition of the present embodiment contains (A) conductive particles containing a metal having a melting point of 200 ° C. or lower, (B) a thermosetting resin, (C) a flux activator, and (D) a curing catalyst. To do. The conductive adhesive composition is used for electrically connecting a flexible wiring board and an electronic component.

(Component (A): Conductive particles)
(A) The conductive particles include a metal having a melting point of 200 ° C. or lower. When such conductive particles are used in the conductive adhesive composition, the conductive particles melt and aggregate at a relatively low temperature (for example, 200 ° C. or lower), so that the mounting temperature of the electronic component on the substrate is low. It is possible to form a connection portion having excellent conductivity without impairing the flexibility and elasticity of the substrate.

The melting point means the melting point of (A) one type of metal contained in the conductive particles, and (A) two or more types of metals contained in the conductive particles. In the case of alloys, etc., it means the melting point of the entire metal. That is, it can be said that the conductive particles (A) include a metal having a melting point of 200 ° C. or lower as a whole metal. The melting point of the metal contained in the (A) conductive particles is preferably 180 ° C. or lower, more preferably 150 ° C. or lower. (A) The lower limit of the melting point of the metal in the conductive particles is not particularly limited, but may be, for example, 100 ° C. The melting point can be measured, for example, by differential scanning calorimetry (DSC).

The metal in the (A) conductive particles is preferably composed of a metal other than lead from the viewpoint of reducing the burden on the environment. Examples of such a metal include one metal selected from the group consisting of tin (Sn), bismuth (Bi), indium (In) and zinc (Zn), or an alloy composed of two or more kinds of metals. .. In addition, since the alloy can obtain better connection reliability, platinum (Pt) and gold (Au) are used in the range where (A) the melting point of the metal as a whole in the conductive particles is 200 ° C. or less. , Silver (Ag), Copper (Cu), Nickel (Ni), Palladium (Pd), Aluminum (Al) and the like may contain a component having a high melting point selected from the group.

Specific examples of the metal 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.), and Sn90. -Ag2-Cu0.5-Bi7.5 solder (melting point 189 ° C.), Sn89-Zn8-Bi3 solder (melting point 190 ° C.), Sn91-Zn9 solder (melting point 197 ° C.), etc. show clear solidification behavior after melting. Therefore, it is preferable. The solidification behavior means that the metal cools and hardens after melting. Among these, it is preferable to use Sn42-Bi58 solder from the viewpoint of excellent availability and low temperature connectivity. These can be used alone or in combination of two or more.

The average particle size of the conductive particles (A) is not particularly limited, but is preferably 0.1 μm or more from the viewpoint of suppressing an increase in the viscosity of the conductive adhesive composition and obtaining better workability. 1 μm or more is more preferable, and 5 μm or more is further preferable. The average particle size of the conductive particles (A) is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less, from the viewpoint of obtaining better printability and connection reliability. From this point of view, the average particle size of the conductive particles (A) is preferably 0.1 to 100 μm. The average particle size of the conductive particles (A) is more preferably 1 to 50 μm from the viewpoint of obtaining better printability and workability of the conductive adhesive composition. Further, the average particle size of the conductive particles (A) is more preferably 5 to 30 μm from the viewpoint of improving the storage stability of the conductive adhesive composition and the mounting reliability of the cured product. Here, the average particle size is obtained by the laser diffraction / scattering method.

The conductive particles (A) are not limited to particles composed only of metals having a melting point of 200 ° C. or lower, and may contain metals having a melting point higher than 200 ° C. Further, the conductive particles (A) are conductive particles in which the surface of particles made of a solid material other than metal such as ceramics, silica, and resin material is coated with a metal film made of metal having a melting point of 200 ° C. or lower. It may be a mixture of a plurality of kinds of conductive particles.

The content of the (A) conductive particles in the conductive adhesive composition is based on the total amount of the conductive adhesive composition from the viewpoint of obtaining better conductivity of the cured product of the conductive adhesive composition. 5% by mass or more is preferable, 10% by mass or more is more preferable, 15% by mass or more is further preferable, and 45% by mass or more is particularly preferable. The content of the (A) conductive particles is from the viewpoint of suppressing the increase in the viscosity of the conductive adhesive composition and obtaining better workability, and (A) conductivity in the conductive adhesive composition. A conductive adhesive composition from the viewpoint of suppressing the content of components other than sex particles (hereinafter, also referred to as "adhesive components") from becoming relatively small and obtaining better mounting reliability of the cured product. 95% by mass or less is preferable, 90% by mass or less is more preferable, and 85% by mass or less is further preferable with respect to the total amount of. From this point of view, the content of the conductive particles (A) is preferably 5 to 95% by mass. The content of the conductive particles (A) is more preferably 10 to 90% by mass from the viewpoint of further improving workability and conductivity, and 15 to 85 from the viewpoint of further improving the mounting reliability of the cured product. Mass% is more preferred.

The (A) conductive particles are used in combination with (a1) conductive particles made of a metal having a melting point higher than 200 ° C. (hereinafter, also referred to as “(a1) conductive particles”) as long as the effects of the present invention are not impaired. You may. Examples of the metal having a melting point higher than 200 ° C. include one kind of metal selected from the group consisting of Pt, Au, Ag, Cu, Ni, Pd, Al and the like, or an alloy composed of two or more kinds of metals. , Au powder, Ag powder, Cu powder and Ag-plated Cu powder. As a commercially available product, for example, "MA05K" (Hitachi Chemical Co., Ltd., trade name), which is an Ag-plated Cu powder, is available.

When (A) conductive particles and (a1) conductive particles are used in combination, the mixing ratio of (A) conductive particles and (a1) conductive particles is 99: 1 to 50:50 in terms of mass ratio. It is preferably in the range of 99: 1 to 60:40, and more preferably in the range of 99: 1 to 60:40.

In the conductive adhesive composition of the present embodiment, from the viewpoint of more effectively exerting the effect according to the present invention, the compounding ratio of the components other than the (A) conductive particles to the (A) conductive particles (adhesive component :. A) Conductive particles) are preferably 5:95 to 50:50 in terms of solid content ratio (mass ratio) in the adhesive composition. Further, from the viewpoint of further excellent adhesiveness, conductivity and workability, the compounding ratio is more preferably 10:90 to 30:70. When this blending ratio is 5:95 or more, the increase in viscosity of the conductive adhesive composition is suppressed, so that better workability can be obtained and the adhesive strength of the conductive adhesive composition is increased. It can be sufficiently secured. When the compounding ratio is 50/50 or less, it is easy to secure conductivity.

(Component (B): thermosetting resin)
(B) The thermosetting resin has an action of adhering an adherend and also acts as a binder component that binds conductive particles in a conductive adhesive composition and a filler added as needed to each other. Examples of such thermosetting resins include thermosetting organic polymer compounds such as epoxy resins, (meth) acrylic resins, maleimide resins, and cyanate resins, and precursors thereof. Here, the (meth) acrylic resin refers to a methacrylic resin and an acrylic resin. Among these, a compound having a polymerizable carbon-carbon double bond typified by a (meth) acrylic resin and a maleimide resin, or an epoxy resin is preferable. These thermosetting resins are excellent in heat resistance and adhesiveness, and can be handled in a liquid state if they are dissolved or dispersed in an organic solvent as needed, so that they are also excellent in workability. Further, from the viewpoint of availability and connection reliability, it is more preferable to use an epoxy resin. These thermosetting resins may be used alone or in combination of two or more.

As the epoxy resin, a known compound can be used without particular limitation as long as it is a compound having two or more epoxy groups in one molecule. Examples of such an epoxy resin include an epoxy resin derived from a phenol compound such as bisphenol A, bisphenol F, and bisphenol AD and epichlorohydridone.

As the epoxy resin, a commercially available product can be used. Examples of the epoxy resin include AER-X8501 (manufactured by Asahi Kasei Co., Ltd., trade name), R-301 (manufactured by Mitsubishi Chemical Co., Ltd., trade name) and YL-980 (Mitsubishi Chemical Co., Ltd.), which are bisphenol A type epoxy resins. YDF-170 (manufactured by Toto Kasei Co., Ltd., trade name), YL-983 (manufactured by Mitsubishi Chemical Co., Ltd., trade name), R-, which is a bisphenol AD type epoxy resin. 1710 (manufactured by Mitsui Chemicals, Inc., trade name), N-730S (trade name, manufactured by DIC Co., Ltd.), Quatrex-2010 (manufactured by Dow Chemical Co., Ltd., trade name), cresol novolak type epoxy resin. Epoxy resin YDCN-702S (manufactured by Toto Kasei Co., Ltd., trade name), EOCN-100 (manufactured by Nippon Kayaku Co., Ltd., trade name), polyfunctional epoxy resin EPPN-501 (manufactured by Nippon Kayaku Co., Ltd., Product name), TACTIX-742 (manufactured by Dow Chemical Co., Ltd., product name), VG-3010 (manufactured by Mitsui Chemical Co., Ltd., product name), 1032S (manufactured by Mitsubishi Chemical Co., Ltd., product name), epoxy with naphthalene skeleton HP-4032 (trade name, manufactured by DIC Co., Ltd.), EHPE-3150, CEL-3000 (all manufactured by Daicel Co., Ltd., trade name), DME-100 (new Nippon Rika Co., Ltd.), which are alicyclic epoxy resins. Company, product name), EX-216L (Nagase Chemtex Co., Ltd., product name), aliphatic epoxy resin W-100 (Shin Nihon Rika Co., Ltd., product name), amine type epoxy resin ELM -100 (manufactured by Sumitomo Chemical Co., Ltd., product name), YH-434L (manufactured by Toto Kasei Co., Ltd., product name), TETRAD-X, TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name), 630, 630LSD (manufactured by Mitsubishi Chemical Co., Ltd., trade name), Denacol EX-201 (manufactured by Nagase ChemteX Co., Ltd., trade name), which is a resorcin type epoxy resin, Denacol EX-221 (Nagase), which is a neopentyl glycol type epoxy resin. Chemtex Co., Ltd., trade name), Denacol EX-212 (Nagase Chemtex Co., Ltd., trade name), hexanediol type epoxy resin, Denacol EX series (EX-810, 811), ethylene propylene glycol type epoxy resin. , 850, 851, 821, 830, 832, 841, 861 (all are Nagase ChemteX Stock Association) (Product name)), epoxy resins E-XL-24 and E-XL-3L represented by the following chemical formula (I) (all manufactured by Mitsui Chemicals, Inc., product name) and the like can be mentioned. Among these epoxy resins, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin and amine type epoxy resin are preferable from the viewpoint of having few ionic impurities and excellent reactivity. These epoxy resins may be used alone or in combination of two or more.

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

When the conductive adhesive composition contains an epoxy resin as the (B) thermosetting resin, an epoxy compound having only one epoxy group in one molecule may be further contained as the reactive diluent. Such epoxy compounds are available as commercial products. Examples of such epoxy compounds include PGE (manufactured by Nippon Kayaku Co., Ltd., trade name), PP-101 (manufactured by Toto Kasei Co., Ltd., trade name), ED-502, ED-509, and ED-509S (any of which). ADEKA Co., Ltd., product name), YED-122 (Mitsubishi Chemical Co., Ltd., product name), KBM-403 (Shinetsu Chemical Industry Co., Ltd., product name), TSL-8350, TSL-8355, TSL-9905 (Both are manufactured by Momentive Performance Materials Japan GK, product name) and so on. These epoxy compounds may be used alone or in combination of two or more.

When the reactive diluent is blended in the adhesive composition, the blending ratio may be within a range that does not impair the effect of the present invention, and may be 0.1 to 30% by mass with respect to the total amount of the epoxy resin. preferable.

The (B) thermosetting resin may contain a (meth) acrylic resin. The (meth) acrylic resin is a polymer having a structural unit derived from a (meth) acrylate compound having a polymerizable carbon-carbon double bond. Here, "(meth) acrylate" refers to methacrylate and acrylate. Examples of such a compound include a monoacrylate compound, a monomethacrylate compound, a diacrylate compound and a dimethacrylate compound.

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, 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, Acryloxyethyl phosphate and acryloxyethylphenyl acid phosphate can be mentioned.

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, Examples thereof include metharoxyethyl phosphate and metharoxyethyl phenyl acid phosphate.

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, and 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 Reactants with moles, 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 Examples include bis (acryloxypropyl) methylsiloxane-dimethylsiloxane copolymer.

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. Reactants with moles, bisphenol A, bisphenol F or bisphenol AD polyethylene oxide adduct dimethacrylate, bisphenol A, bisphenol F or bisphenol AD polypropylene oxide adduct dimethacrylate, bis (methacryloxypropyl) polydimethylsiloxane and Examples thereof include bis (methacryloxypropyl) methylsiloxane-dimethylsiloxane copolymer.

These (meth) acrylate compounds may be used alone or in combination of two or more. When the (B) thermosetting resin contains a (meth) acrylic resin, the (meth) acrylate compound may be polymerized in advance and used, and the (meth) acrylate compound is used as (A) conductive particles and (C) flux activity. Polymerization may be carried out at the same time as mixing with an agent or the like.

As the (meth) acrylic resin, a commercially available product can be used. Examples of the (meth) acrylic resin include FINEDIC A-261 and FINEDIC A-229-30 (both manufactured by DIC Corporation, trade names).

When the thermosetting resin (B) contains a (meth) acrylic resin, the conductive adhesive composition preferably contains a radical polymerization initiator. As the radical polymerization initiator, a commonly used one can be used. Examples of the radical polymerization initiator include organic peroxides such as benzoyl peroxide and t-butylperoxy-2-ethylhexanoate, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile. Can be mentioned. As the radical polymerization initiator, an organic peroxide is preferable from the viewpoint of effectively suppressing voids and the like. Further, from the viewpoint of further improving the curability and viscosity stability of the adhesive component, the decomposition temperature of the organic peroxide is preferably 130 ° C. to 200 ° C.

The blending ratio of the radical polymerization initiator is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and 0.5 to 5% with respect to the total amount of the conductive adhesive composition. It is more preferably by mass%.

The content of the (B) thermosetting resin in the conductive adhesive composition is preferably 1% by mass or more, preferably 5% by mass, based on the total amount of the conductive adhesive composition, from the viewpoint of obtaining further excellent adhesive strength. % Or more is more preferable, and 10% by mass or more is further preferable. The content of the thermosetting resin (B) is preferably 60% by mass or less, more preferably 40% by mass or less, based on the total amount of the conductive adhesive composition, from the viewpoint of easily ensuring sufficient conductivity. More preferably, it is 30% by mass or less. That is, the content of the (B) thermosetting resin in the conductive adhesive composition may be 1 to 60% by mass, or 5 to 40% by mass, based on the total amount of the conductive adhesive composition. It may be 10 to 30% by mass.

(Component (C): flux activator)
The (C) flux activator exhibits the ability to (A) remove the oxide film formed on the surface of the conductive particles. By using such a flux activator, (A) an oxide film that hinders melt aggregation of conductive particles is removed. As the flux activator (C), a known compound can be used without particular limitation as long as it does not inhibit the curing reaction of the (B) thermosetting resin.

Examples of the (C) flux activator include a rosin-based resin, a compound having a carboxyl group, a compound having a hydroxyl group, and a compound having a hydroxyl group and a carboxyl group. Examples of the hydroxyl group include a phenolic hydroxyl group and an alcoholic hydroxyl group. Among these, a compound having a hydroxyl group and a carboxyl group is preferable because it exhibits good flux activity and (B) reactivity with an epoxy resin that can be used as a thermosetting resin, and is an aliphatic dihydroxycarboxylic acid. Acids are more preferred. As the compound having a hydroxyl group and a carboxyl group, specifically, a compound represented by the following general formula (V) or tartaric acid is preferable.

In the formula (V), R ⁵ represents an alkyl group having 1 to 5 carbon atoms, and a methyl group, an ethyl group or a propyl group is preferable from the viewpoint of more effectively exhibiting good connection strength and connection reliability. Further, n and m each independently represent an integer of 0 to 5, and from the viewpoint of more effectively exhibiting good connection strength and connection reliability, n is 0 and m is 1, or both n and m. Is preferably 1.

Examples of the compound represented by the general formula (V) include 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butane and 2,2-bis (hydroxymethyl) pentane. Acid is mentioned.

The content of the flux activator (C) is (A) conductive from the viewpoint that the decrease in the meltability of the metal is suppressed when the amount of the surface oxide film at the connecting portion is large and excellent conductivity can be easily obtained. 0.5 parts by mass or more is preferable, and 1 part by mass or more is more preferable with respect to 100 parts by mass of the total amount of the sex particles. The content of the flux activator (C) is preferably 20 parts by mass or less, preferably 15 parts by mass, based on 100 parts by mass of the total amount of the (A) conductive particles, from the viewpoint that excellent storage stability and printability can be easily obtained. More preferably, it is 10 parts by mass or less. The content of the flux activator (C) is 0.5 to 20 parts by mass with respect to 100 parts by mass of the total amount of (A) conductive particles from the viewpoint of more effectively obtaining good connection strength and connection reliability. Preferably, 0.5 to 15 parts by mass is more preferable. The content of the flux activator (C) is more preferably 1 to 10 parts by mass, and particularly preferably 1 to 5 parts by mass, from the viewpoint of further excellent storage stability and conductivity.

(Component (D): Curing catalyst)
The (D) curing catalyst has the effect of accelerating the curing of the (B) thermosetting resin. As the curing catalyst (D), an imidazole compound is preferable from the viewpoints of curability at a desired curing temperature, length of pot life, heat resistance of the obtained cured product, and the like. Of these, a curing agent for imidazole epoxy resin is more preferable. Examples of commercially available imidazole compounds include 2P4MHZ-PW (2-phenyl-4-methyl-5-hydroxymethylimidazole), 2PHZ-PW (2-phenyl-4,5-dihydroxymethylimidazole), and 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) and 2MAOK-PW (2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine isocyanuric acid adduct) (both Shikoku Kasei Kogyo Co., Ltd., trade name). These curing catalysts can be used alone or in combination of two or more.

The content of the (D) curing catalyst is preferably 0.01 part by mass or more, preferably 0.1 part by mass or more, based on 100 parts by mass of the (B) thermosetting resin, from the viewpoint that excellent curability can be easily obtained. Is more preferable. The content of the curing catalyst is preferably 90 parts by mass or less, more preferably 50 parts by mass or less, from the viewpoint that the increase in viscosity is suppressed and excellent workability when handling the conductive adhesive composition can be easily obtained. preferable. That is, the content of the (D) 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 (B) thermosetting resin. ..

(Other ingredients)
In the conductive adhesive composition of the present embodiment, in addition to the above-mentioned components, if necessary, a flexible agent for stress relaxation and an additive for improving workability (diluent, adhesive strength improving agent) , At least one selected from the group consisting of a wettability improver and an antifoaming agent) may be contained. In addition to these components, various additives may be contained as long as the effects according to the present invention are not impaired.

Examples of the flexible agent include liquid polybutadiene (manufactured by Ube Industries, Ltd., trade name "CTBN-1300 × 31", “CTBN-1300 × 9”, manufactured by Nippon Soda Corporation, trade name “NISSO-PB-C-”. 2000 ") and the like. When a flexible agent is contained, the content of the flexible agent is preferably 0.1 to 500 parts by mass with respect to 100 parts by mass of the (B) thermosetting resin.

A diluent can be added to the conductive adhesive composition of the present embodiment, if necessary, in order to improve workability during preparation of the paste-like composition and coating workability during use. Examples of such a diluent include organic solvents having a relatively high boiling point such as butyl carbitol, butyl cellosolve, carbitol, butyl celloacetate acetate, carbitol acetate, dipropylene glycol monomethyl ether, ethylene glycol diethyl ether, and α-terpineol. preferable. When these diluents are contained, the content of the diluent is preferably 0.1 to 30% by mass with respect to the total amount of the conductive adhesive composition.

The conductive adhesive composition of the present embodiment may contain a coupling agent such as a silane coupling agent or a titanium coupling agent as an adhesive strength improving agent. Examples of the silane coupling agent include KBM-573 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name) and the like. Further, the conductive adhesive composition of the present embodiment may contain a wettability improving agent such as an anionic surfactant and a fluorine-based surfactant. Further, the conductive adhesive composition of the present embodiment may contain silicone oil or the like as a defoaming agent. As the adhesive strength improver, the wettability improver and the defoamer, one kind may be used alone or two or more kinds may be used in combination. When these additives are contained, the content of each additive is preferably 0.1 to 10% by mass with respect to the total amount of the conductive adhesive composition.

The conductive adhesive composition of the present embodiment 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 can be used alone or in combination of two or more.

The conductive adhesive composition of the present embodiment may further contain a curing agent in order to adjust the curing rate of the (B) thermosetting resin (for example, epoxy resin).

The curing agent is not particularly limited as long as it is conventionally used, and commercially available ones are available. Examples of commercially available curing agents include H-1 (manufactured by Meiwa Kasei Co., Ltd., trade name) which is a phenol novolac resin, VR-9300 (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name), and XL which is a phenol aralkyl resin. -225 (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name), MTPC (manufactured by Honshu Chemical Industry Co., Ltd., trade name), which is a p-cresol novolac resin represented by the following general formula (II), allylated phenol novolac resin. AL-VR-9300 (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name), PP-700-300 (manufactured by Nippon Petrochemical Co., Ltd., trade name), which is a phenolic resin represented by the following general formula (III). And so on.

In formula (II), R ¹ independently represents a monovalent hydrocarbon group, preferably a methyl group or an allyl group, and q represents an integer of 1 to 5.

In formula (III), R ² independently represents an alkyl group, preferably a methyl group or an ethyl group, R ³ represents a hydrogen atom or a monovalent hydrocarbon group, and p is an integer of 2 to 4. Shown.

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

Wherein (IV), R ⁴ represents a divalent aromatic group or a linear or branched alkylene group having 1 to 12 carbon atoms, preferably a m- phenylene or p- phenylene.

From the viewpoint of storage stability and curing time, it is preferable that the curing agent is not substantially contained in the conductive adhesive composition. The term "substantially free" means that the content is 0.05% by mass or less based on the total amount of the conductive adhesive composition.

In the present embodiment, each of the above-mentioned components may be combined with any of those exemplified in each.

The conductive adhesive composition of the present embodiment is a paste-like composition in which each component is uniformly dispersed by mixing, dissolving, pulverizing and kneading or dispersing each of the above-mentioned components at one time or in a plurality of times. Obtained as. When the paste-like composition is obtained, it may be heated if necessary. Examples of the disperser and the dissolution device include known stirrers, rakers, three rolls and planetary mixers.

The viscosity of the conductive adhesive composition of the present embodiment at 25 ° C. is preferably 5 to 400 Pa · s, more preferably 50 to 300 Pa · s, and 100 to 100 to 300 Pa · s from the viewpoint of paste applicability. It is more preferably 200 Pa · s. The viscosity can be measured by, for example, a B-type viscometer manufactured by Eiko Seiki Co., Ltd.

The conductive adhesive composition of the present embodiment described above has good adhesive strength and conductivity, and is a cured product capable of achieving both good adhesive strength and conductivity even after repeated expansion and contraction and bending. Can be formed. Further, since the conductive adhesive composition of the present embodiment can lower the mounting temperature in the mounting process of the flexible wiring board and the electronic component, the electronic component does not impair the flexibility and elasticity of the substrate. It is possible to obtain a connection structure such as a mounting flexible wiring board. Further, since the adhesive composition according to the present embodiment can form a connecting portion having a connecting structure in which the metal portion and the resin portion are separated, the connecting portion is reinforced, and only bending resistance and stretch resistance are required. It is possible to obtain a connection structure having excellent TCT resistance. The conductive adhesive composition can be used for a stretchable device composed of a flexible wiring board and an electronic component in which the used form is in a bent state or a stretched shape.

<Connection structure>
The connection structure of the present embodiment includes a flexible wiring board having a first connection terminal, an electronic component having a second connection terminal, and a connection portion arranged between the flexible wiring board and the electronic component. It is a connection structure in which the connection portion contains the cured product of the conductive adhesive composition of the present embodiment, and the first connection terminal and the second connection terminal are electrically connected.

The flexible wiring board is preferably composed of a base material having flexibility and elasticity. Flexible and stretchable substrates include, for example, polyimide, polyethylene terephthalate (PET), polycarbonate, polyethylene naphthalate (PEN), polyketone, polyetheretherketone, thermoplastic polyurethane elastomer (TPU) and cycloolefin polymer. Can be mentioned. Among these, thermoplastic polyurethane elastomer, polyethylene terephthalate and polyethylene naphthalate are preferable, and thermoplastic polyurethane elastomer is more preferable, from the viewpoint of dimensional stability after wiring processing.

The electronic component is not particularly limited, and a known electronic component can be used. Specific examples thereof include semiconductor light emitting elements, capacitors, Schottky barrier diodes, driver integrated circuits (driver ICs), and the like. Examples of the semiconductor light emitting element include an LED-SMD package, an LED flip chip, and an LED-CSP.

The connecting portion contains a cured product of the conductive adhesive composition of the present embodiment, and is composed of a metal portion containing a metal having a melting point of 200 ° C. or lower and a resin portion containing a thermosetting resin. It is possible to take an aspect having a connection structure consisting of. The metal portion preferably contains a metal derived from conductive particles (A) containing a metal having a melting point of 200 ° C. or lower as a main component, and the resin portion contains a resin derived from an adhesive component such as a thermosetting resin. It is preferably used as the main component. In the connection structure according to the present embodiment, when viewed in a cross section orthogonal to the upper surface of the second connection terminal of the electronic component, the metal portion is the second connection terminal of the electronic component and the first connection of the flexible wiring board. It is in contact with the terminal, and the resin portion can take a form existing around the metal portion.

The area ratio of the metal part to the resin part (metal part: resin part) at the connection part is 5:95 to 80:20 from the viewpoint of maintaining the adhesive strength and conductivity even better even if bending and expansion and contraction are repeated. It is preferably 10:90 to 90:10, and even more preferably 30:70 to 70:30. The area ratio can be obtained by observing the cross section of the connecting portion. Further, a sealing member may be further provided around the resin portion.

The connection structure of the present embodiment can be obtained by adhering an electronic component and a flexible wiring board using the above-mentioned conductive adhesive composition. For example, first, the conductive adhesive composition is applied onto the connection terminals of the flexible wiring board by a dispensing method, a screen printing method, a stamping method, or the like. Next, the electronic component is laminated on the flexible wiring board so that the connection terminal of the electronic component and the connection terminal of the flexible wiring board are in contact with each other via the conductive adhesive composition. After that, the conductive adhesive composition is heat-cured using a heating device such as an oven or a reflow furnace, and the flexible wiring board and the electronic component are electrically connected via the cured product of the conductive adhesive composition. A connection structure having such a structure can be obtained (hereinafter, this connection structure is also referred to as an "electronic component mounting flexible wiring board").

Examples of the flexible wiring board on which electronic components are mounted include a flexible wiring board on which a semiconductor light emitting element is mounted. In the flexible wiring board on which the semiconductor light emitting element is mounted, a flexible wiring board having a first connection terminal, a semiconductor light emitting element having a second connection terminal, and a connection portion arranged between the flexible wiring board and the semiconductor light emitting element. The connection portion may contain a cured product of the conductive adhesive composition, and the first connection terminal and the second connection terminal may be electrically connected to each other.

Next, the connection structure of the present embodiment will be described with reference to FIGS. However, the dimensional ratios in the drawings are not limited to the ratios shown. FIG. 1 is a schematic cross-sectional view showing an embodiment of a flexible wiring board on which electronic components are mounted. As shown in FIG. 1, the electronic component mounting flexible wiring board 1 has a substrate connection terminal 7 (first connection terminal) formed on the flexible wiring board 5 and an electronic component connection terminal 6 formed on the electronic component 4. (Second connection terminal) has a structure in which it is joined to each other by a connecting portion 8 and electrically connected to each other. The connecting portion 8 contains a cured product obtained by curing the above-mentioned conductive adhesive composition. Further, the connecting portion 8 is composed of a metal portion 8a and a resin portion 8b.

The flexible wiring board on which electronic components are mounted according to the present embodiment is not limited to the structure shown in FIG. 1, and may have, for example, the structure shown in FIGS. 2 or 3. FIG. 2 is a schematic cross-sectional view showing another embodiment of the flexible wiring board on which electronic components are mounted. The electronic component mounting flexible wiring board 2 shown in FIG. 2 has a substrate connection terminal 7 (first connection terminal) formed on the flexible wiring board 5 and a lead 9 (second connection) connected to the electronic component 4. The terminal) has a structure in which it is electrically connected by a connecting portion 8 containing a cured product obtained by curing the conductive adhesive composition of the present embodiment. Further, the connecting portion 8 is composed of a metal portion 8a and a resin portion 8b.

Further, FIG. 3 is a schematic cross-sectional view showing still another embodiment of the flexible wiring board on which electronic components are mounted. The electronic component mounting flexible wiring board 3 shown in FIG. 3 has a structure in which the flexible wiring board 5 and the electronic component 4 are connected by combining the conductive adhesive composition of the present embodiment and solder. In the electronic component mounting flexible wiring board 3, an electronic component connection terminal 6 is formed on the electronic component 4, and a solder ball 10 is further formed on the electronic component connection terminal 6. Then, the solder balls 10 and the substrate connection terminal 7 formed on the flexible wiring board 5 are electrically connected by a connecting portion 8 containing a cured product obtained by curing the conductive adhesive composition of the present embodiment. The flexible wiring board 3 for mounting electronic components is formed. Further, the connecting portion 8 is composed of a metal portion 8a and a resin portion 8b.

The flexible wiring boards 1 to 3 on which the electronic components are mounted shown in FIGS. 1 to 3 are cured products obtained by curing the conductive adhesive composition of the present embodiment by the connection terminals on the substrate and the connection terminals on the electronic components, respectively. It has a structure that is joined to each other and electrically connected by a connecting portion including. The connection portion is composed of a metal portion 8a and a resin portion 8b, and the metal portion 8a is reinforced by the resin portion 8b. Here, in the conventional flexible wiring board for mounting electronic components in which the connection portion is composed of only the metal portion, when the bending test and the expansion / contraction test are performed, the substrate is greatly deformed and the connection portion and the electronic component are directly distorted. This may cause damage to the connections and electronic components. In the electronic component mounting flexible wiring board in which the connection portion of the present embodiment is composed of a metal portion and a resin portion, since the metal portion is reinforced by the resin portion, the deformation of the substrate is resin even if the substrate is significantly deformed. It is possible to keep the rigid state of the connection part by being stopped by the part.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Further, the present invention can be variously modified without departing from the gist thereof. For example, another substrate, an electronic component, or the like may be mounted on the substrate in the connection structure shown in FIGS. 1 to 3.

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

<Preparation of conductive adhesive composition>
[Example 1]
YL980 (bisphenol F type epoxy resin, manufactured by Mitsubishi Chemical Co., Ltd., trade name) 16.0 parts by mass, which is a thermosetting resin, and 2P4MHZ-PW (imidazole compound, manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name) which is a curing catalyst. ) 1.3 parts by mass and 2.7 parts by mass of BHPA (2,2-bis (hydroxymethyl) propionic acid) which is a flux activator are mixed and passed through 3 rolls 3 times to prepare an adhesive component. did.

Next, 80 parts by mass of Sn42-Bi58 solder (average particle diameter 20 μm, manufactured by Mitsui Mining & Smelting Co., Ltd., melting point 138 ° C.), which is conductive particles, was added to 20 parts by mass of the above-mentioned adhesive component to make a planetary mixer. A conductive adhesive composition was obtained by stirring using the material and defoaming at 500 Pa or less for 10 minutes.

[Examples 2 to 8 and Comparative Examples 1 to 7]
Conductive adhesive compositions of Examples 2 to 8 and Comparative Examples 1 to 7 were obtained in the same manner as in Example 1 except that the compositions and blending amounts shown in Tables 1 and 2 below were used. The unit of the blending amount of each component in the table is a mass part.

Details of each component in the table are as follows.
YL980: Bisphenol F type epoxy resin, manufactured by Mitsubishi Chemical Co., Ltd., trade name 2P4MHZ-PW: imidazole compound, manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name BHPA: 2,2-bis (hydroxymethyl) propionic acid BHBA: 2,2 -Bis (hydroxymethyl) butanoate Sn42-Bi58 solder: average particle size 20 μm, manufactured by Mitsui Mining & Smelting Co., Ltd., melting point 138 ° C.
Sn42-Bi57-Ag1 solder: average particle diameter 20 μm, manufactured by Mitsui Mining & Smelting Co., Ltd., melting point 139 ° C.
Sn96.5-Ag3-Cu0.5 Solder: Average particle size 20 μm, manufactured by Mitsui Mining & Smelting Co., Ltd., melting point 217 ° C.
Ag paste: manufactured by Fujikura Kasei Co., Ltd., curing temperature 150 ° C
Sn42-Bi58 cream solder: manufactured by Senju Metal Industry Co., Ltd., melting point 138 ° C.
Sn96.5-Ag3-Cu0.5 cream solder: manufactured by Senju Metal Industry Co., Ltd., melting point 219 ° C.

<Characteristic evaluation>
The characteristics of the conductive adhesive compositions obtained in the above Examples and Comparative Examples were evaluated by the following methods. The results are summarized in Tables 1 and 2 below.

TPU (thermoplastic polyurethane elastomer) having flexibility and elasticity was used as the base material of the flexible wiring board used for the evaluation of TCT resistance, bending resistance and elasticity.

(1) Adhesiveness (adhesive strength)
Approximately 0.5 mg of the conductive adhesive composition is applied onto a silver-plated copper plate, and a rectangular flat plate-shaped tin-plated copper plate having a length of 2 mm, a width of 2 mm, and a thickness of 0.25 mm is crimped onto the test piece. Obtained. Then, the test pieces of Examples 1 to 8 and Comparative Examples 1 to 6 were subjected to a heat history of 150 ° C. for 10 minutes. A heat history of 260 ° C. for 10 minutes was added to the test piece of Comparative Example 7. Next, for the test pieces of Examples 1 to 8 and Comparative Examples 1 to 7, the share strength at 25 ° C. was measured by a bond tester (manufactured by DAGE, model number: 2400) at a share rate of 500 μm / sec and a clearance of 100 μm. did.

(2) Conductivity (volume resistivity)
Two strip-shaped gold-plated copper plates having a width of 1 mm, a length of 50 mm, and a thickness of 0.03 mm are bonded to each other in a cross shape so as to be orthogonal to each other via the adhesive composition, and the adhesive layer (orthogonal portion). A test piece having a size of 1 mm in width × 1 mm in length × 0.03 mm in thickness was obtained. Subsequently, the same thermal history as the adhesiveness evaluation in (1) above was added to the test piece. Then, the volume resistivity in the thickness direction of the test piece was measured by the four-terminal method.

(3) TCT resistance A rectangular flat plate-shaped TPU substrate having a length of 100 mm, a width of 50 mm, and a thickness of 1.0 mm provided with a copper foil land of 1.7 mm × 1.4 mm was prepared. Next, the adhesive composition was printed on a copper foil land using a metal mask (thickness 100 μm, opening size 1.0 mm × 1.6 mm), and a chip resistor (3.2 mm × 1.6 mm, MCR manufactured by ROHM Co., Ltd.) was printed. ) Was installed. The same thermal history as in the adhesiveness evaluation in (1) above was added to this component mounting substrate to obtain a test substrate for TCT resistance evaluation. This test substrate is held by ESPEC CORPORATION TSE-11-A (1 cycle: -55 ° C. for 30 minutes, temperature rise to 125 ° C. in 5 minutes, 125 ° C. for 30 minutes, -55), which is a thermal shock tester. The temperature was lowered to ℃ in 5 minutes), and the connection resistance was measured. The evaluation of TCT resistance was based on the number of cycles showing a resistance change rate within ± 10% of the initial resistance value.

(4) Bending resistance A rectangular flat plate-shaped TPU substrate having a length of 200 mm, a width of 20 mm, and a thickness of 1.0 mm provided with a copper foil land of 1.7 mm × 1.4 mm was prepared. Next, the adhesive composition was printed on a copper foil land using a metal mask (thickness 100 μm, opening size 1.0 mm × 1.6 mm), and a chip resistor (3.2 mm × 1.6 mm, MCR manufactured by ROHM Co., Ltd.) was printed. ) Was installed. The same thermal history as in the adhesiveness evaluation in (1) above was added to this component mounting substrate to obtain a test substrate for bending resistance evaluation. This test board is bent into a U-shape on a U-shaped folding tester (Yuasa System Co., Ltd., DLDMLH-FU) with a bending radius of 2.0 mm so that the component mounting part is on the inside. Both ends of the substrate are attached to the sliding plate and the fixing plate, and the sliding plate is slid left and right with a stroke of 50 mm and a sliding speed of 100 times / minute in a test atmosphere of 23 ° C., and the test substrate is repeatedly bent a predetermined time. The resistance value of the component mounting part was measured when the parts were mounted. In the evaluation of bending resistance, the number of sliding times when the initial resistance value increased by 10% was defined as the bending resistance life.

(5) Stretch resistance A rectangular flat plate-shaped TPU substrate having a length of 200 mm, a width of 20 mm, and a thickness of 1.0 mm provided with a copper foil land of 1.7 mm × 1.4 mm was prepared. Next, the adhesive composition was printed on a copper foil land using a metal mask (thickness 100 μm, opening size 1.0 mm × 1.6 mm), and a chip resistor (3.2 mm × 1.6 mm, MCR manufactured by ROHM Co., Ltd.) was printed. ) Was installed. The same thermal history as in the adhesiveness evaluation in (1) above was added to this component mounting substrate to obtain a test substrate for stretch resistance evaluation. This test substrate was repeatedly fixed to both ends in a telescopic tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd., DC-210) so that it was in the most contracted state, and the test atmosphere was 23 ° C. The resistance value when the plant was repeatedly expanded and contracted a predetermined number of times at 100 times / minute was measured. In the evaluation of the stretch resistance, the number of stretches and contractions at the time when the initial resistance value increased by 10% was defined as the stretch resistance life.

All of Examples 1 to 8 showed good adhesive strength, volume resistivity, TCT resistance, bending resistance and stretch resistance.

In Comparative Examples 1 and 3, it was confirmed that the metal particles did not aggregate and there was a problem in connectivity. It was confirmed that in Comparative Examples 2, 4 and 6, although the metal bonding was good, the TCT resistance, bending resistance and stretch resistance were inferior to those of Examples 1 to 8. It was confirmed that Comparative Example 5 was inferior to Examples 1 to 8 in all of adhesive strength, volume resistivity, TCT resistance, bending resistance and stretch resistance. Further, Comparative Example 7 showed good connection strength and volume resistivity, but with respect to TCT resistance, bending resistance and expansion / contraction resistance, the TPU substrate was significantly deformed when heat-connected at 260 ° C. It was impossible to measure because the connection part was damaged.

1,2,3 ... Flexible wiring board with electronic components, 4 ... Electronic components, 5 ... Flexible wiring board, 6 ... Electronic component connection terminals, 7 ... Board connection terminals, 8 ... Connections, 8a ... Metal parts, 8b ... Resin Parts, 9 ... leads, 10 ... solder balls.

Claims (13)

A conductive adhesive composition used for electrically connecting a flexible wiring board and an electronic component.
It contains conductive particles containing a metal having a melting point of 200 ° C. or lower, a thermosetting resin, a flux activator, and a curing catalyst, and the content of the conductive particles is 5 with respect to the total amount of the conductive adhesive composition. The content of the thermosetting resin is 1% by mass or more and 60% by mass or less, and the content of the flux activator is 1% by mass or more and 60% by mass or less with respect to the total amount of the conductive adhesive composition. However, the total amount of the conductive particles is 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass, and the content of the curing catalyst is 0.01 mass by mass with respect to 100 parts by mass of the thermosetting resin. More than 90 parts and less than 90 parts
The conductive particles are composed of Sn42-Bi58 solder, Sn48-In52 solder, Sn42-Bi57-Ag1 solder, Sn90-Ag2-Cu0.5-Bi7.5 solder, Sn89-Zn8-Bi3 solder, and Sn91-Zn9 solder. Including at least one selected from the group,
The flux activator is at least selected from the group consisting of 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,2-bis (hydrochimethyl) pentanoic acid and tartaric acid. It is an aliphatic dihydroxycarboxylic acid containing one kind ,
The thermosetting resin contains an epoxy resin and contains
A conductive adhesive composition in which the curing catalyst contains an imidazole compound . The conductive adhesive composition according to claim 1, which is a paste-like composition having a viscosity at 25 ° C. of 5 to 400 Pa · s. The conductive adhesive composition according to claim 1 or 2 , which is used for electrically connecting a connection terminal arranged on the flexible wiring board and a connection terminal arranged on the electronic component. The conductive adhesive composition according to any one of claims 1 to 3 , wherein the flexible wiring board is composed of a base material having flexibility and elasticity. The flexible wiring substrate is composed of a substrate containing at least one selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, polyethylene naphthalate, polyketone, polyetheretherketone, thermoplastic polyurethane elastomer and cycloolefin polymer. The conductive adhesive composition according to any one of claims 1 to 4 . A flexible wiring board having a first connection terminal,
Electronic components with a second connection terminal
The flexible wiring board and the connection portion arranged between the electronic components are provided.
The connection portion contains a cured product of the conductive adhesive composition according to any one of claims 1 to 5 , and the first connection terminal and the second connection terminal are electrically connected. The connection structure. The connection structure according to claim 6 , wherein the connection portion has a connection structure including a metal portion containing a metal having a melting point of 200 ° C. or lower and a resin portion containing a thermosetting resin. When the connection structure is viewed in a cross section orthogonal to the upper surface of the second connection terminal, the metal portion is in contact with the second connection terminal and the first connection terminal, and the resin portion is the metal portion. The connection structure according to claim 7 , which has a connection structure existing around. The connection structure according to claim 7 or 8 , wherein the area ratio of the metal portion to the resin portion is 5:95 to 80:20. The connection structure according to any one of claims 7 to 9 , further comprising a sealing member around the resin portion. The flexible wiring substrate is composed of a base material containing at least one selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, polyethylene naphthalate, polyketone, polyetheretherketone, thermoplastic polyurethane elastomer and cycloolefin polymer. The connection structure according to any one of claims 6 to 10 . The connection structure according to any one of claims 6 to 11 , wherein the electronic component includes at least one selected from the group consisting of a semiconductor light emitting element, a capacitor, a Schottky barrier diode, and a driver integrated circuit. A flexible wiring board having a first connection terminal,
A semiconductor light emitting device having a second connection terminal and
A connection portion arranged between the flexible wiring board and the semiconductor light emitting element is provided.
The connection portion contains a cured product of the conductive adhesive composition according to any one of claims 1 to 5 , and the first connection terminal and the second connection terminal are electrically connected. Flexible wiring board with semiconductor light emitting elements.

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