JP7014576B2 - Conductive material, connection structure and method for manufacturing the connection structure - Google Patents

Description

The present invention relates to a conductive material containing solder particles. The present invention also relates to a connection structure using the above conductive material and a method for manufacturing the connection structure.

Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In the anisotropic conductive material, the conductive particles are dispersed in the binder resin.

The anisotropic conductive material is used to obtain various connection structures. Examples of the connection using the anisotropic conductive material include a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), and a semiconductor. Examples thereof include a connection between a chip and a glass substrate (COG (Chip on Glass)) and a connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

With the anisotropic conductive material, for example, when the electrode of the flexible printed circuit board and the electrode of the glass epoxy board are electrically connected, the anisotropic conductive material containing the conductive particles is arranged on the glass epoxy board. do. Next, the flexible printed substrates are laminated, heated and pressurized. As a result, the anisotropic conductive material is cured, and the electrodes are electrically connected to each other via the conductive particles to obtain a connection structure.

Patent Document 1 below discloses a flux for soldering containing a base resin, an activator and a solvent. The solvent contains an organic acid anhydride that is liquid at 20 ° C. or higher and a polyhydric alcohol that is liquid at 20 ° C. or higher. The acid value of the organic acid anhydride is AV (mgKOH / g), the content thereof is WA (g), the acid value of the polyhydric alcohol is OHV (mgKOH / g), and the content thereof is WOH (g). AV × WA: OHV × WOH = 1: 0.4 to 1: 0.6 is satisfied. Further, Patent Document 1 discloses a solder paste composition containing the soldering flux and the solder alloy powder.

Patent Document 2 below discloses a soldering flux containing an epoxy resin, an organic carboxylic acid containing 0.1% by mass to 40% by mass of a dicarboxylic acid having a molecular weight of 180 or less, and a thixo agent. In the soldering flux, the epoxy resin and the organic carboxylic acid are such that the carboxyl group of the organic carboxylic acid is 0.8 equivalent to 2.0 equivalent with respect to 1.0 equivalent of the epoxy group of the epoxy resin. It is mixed with acid. In the soldering flux, the total content of the epoxy resin, the organic carboxylic acid, and the thixo agent is 70% by mass or more with respect to the total amount of the flux. Patent Document 2 discloses a solder composition containing the soldering flux and lead-free solder having a melting point of 190 ° C. to 240 ° C.

Patent Document 3 below discloses a conductive paste containing a thermosetting component and a plurality of solder particles. The zeta potential on the surface of the solder particles is positive. Although Patent Document 3 describes that a compound having a high dielectric constant may be added to the conductive paste, the dielectric constant of the compound having a high dielectric constant is preferably 4 or more. It is only stated that it is preferably 7 or less.

WO2009 / 069601A1 WO2015 / 115483A1 WO2015 / 125778A1

In recent years, fine pitching of wiring in printed wiring boards and the like has been progressing. Along with this, in the conductive material containing the solder particles or the conductive particles having the solder on the surface, the solder particles or the conductive particles having the solder on the surface are becoming smaller and smaller in diameter.

When the solder particles or the like are simply reduced in diameter, there is a problem that the solder particles or the like cannot be efficiently arranged between the upper and lower electrodes to be connected at the time of conductive connection using a conductive material. In particular, when the conductive material is heat-cured, solder particles and the like cannot be sufficiently aggregated on the vertical electrodes to be connected, the viscosity of the conductive material increases, and the conductive material must not be connected in the horizontal direction. Solder particles or the like may remain as side balls or the like between the electrodes, apart from the solder between the electrodes in the vertical direction. As a result, it may not be possible to sufficiently enhance the conduction reliability between the electrodes to be connected and the insulation reliability between adjacent electrodes that should not be connected.

Further, as the diameter of the solder particles becomes smaller, the surface area of the solder particles increases, so that the total amount of oxides formed by the oxide film on the surface of the solder particles also increases. If an oxide film is present on the surface of the solder particles or the like, the solder particles or the like cannot be efficiently aggregated on the electrode. Therefore, in the conventional conductive material, measures such as increasing the flux content in the conductive material are taken. You will need it. However, if the content of the flux in the conductive material is increased, voids may be generated in the cured product of the conductive material or poor curing of the conductive material may occur. It is difficult to solve the above problems with conventional conductive materials.

An object of the present invention is to provide a conductive material capable of efficiently arranging solder particles on an electrode and further effectively suppressing the occurrence of curing failure of the conductive material. Another object of the present invention is to provide a connection structure using the above conductive material and a method for manufacturing the connection structure.

According to a broad aspect of the present invention, the thermosetting component, a plurality of solder particles, and an additive having a relative permittivity of 30 or more are contained, and the content of the additive with respect to 100 parts by weight of the thermosetting component. However, a conductive material having a weight of 0.5 parts by weight or more and 10 parts by weight or less is provided.

In a specific aspect of the conductive material according to the present invention, the content of the additive is 0.1% by weight or more and 3% by weight or less in 100% by weight of the conductive material.

In certain aspects of the conductive material according to the present invention, the conductive material comprises a flux.

In a specific aspect of the conductive material according to the present invention, the gel fraction when the component excluding the solder particles in the conductive material is heated at 160 ° C. for 60 minutes is 70% or more and 100% or less.

In certain aspects of the conductive material according to the present invention, the conductive material is a conductive paste.

According to a broad aspect of the present invention, a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, and the first connection target member. A connection portion connecting the second connection target member is provided, the material of the connection portion is the above-mentioned conductive material, and the first electrode and the second electrode are the connection portion. A connection structure is provided that is electrically connected by a solder portion inside.

In a specific aspect of the connection structure according to the present invention, the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the portion, the solder portion in the connection portion is arranged in 50% or more of the area of 100% of the portion where the first electrode and the second electrode face each other.

According to a broad aspect of the present invention, the step of arranging the conductive material on the surface of the first connection target member having the first electrode on the surface using the above-mentioned conductive material, and the step of the conductive material. A second connection target member having a second electrode on the surface is arranged on a surface opposite to the first connection target member side so that the first electrode and the second electrode face each other. By heating the conductive material above the melting point of the solder particles in the step, a connecting portion connecting the first connection target member and the second connection target member is formed by the conductive material. Further, a method for manufacturing a connection structure is provided, which comprises a step of electrically connecting the first electrode and the second electrode by a solder portion in the connection portion.

In a specific aspect of the method for manufacturing a connection structure according to the present invention, the first electrode and the second electrode are provided in the stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the facing portions, the connection in which the solder portion in the connecting portion is arranged in 50% or more of the area of 100% of the facing portions of the first electrode and the second electrode. Get the structure.

The conductive material according to the present invention contains a thermosetting component, a plurality of solder particles, and an additive having a relative permittivity of 30 or more. In the conductive material according to the present invention, the content of the additive with respect to 100 parts by weight of the thermosetting component is 0.5 parts by weight or more and 10 parts by weight or less. Since the conductive material according to the present invention has the above-mentioned configuration, the solder particles can be efficiently arranged on the electrodes, and further, the occurrence of curing failure of the conductive material can be effectively suppressed. ..

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained by using the conductive material according to the embodiment of the present invention. 2 (a) to 2 (c) are cross-sectional views for explaining each step of an example of a method of manufacturing a connection structure using the conductive material according to the embodiment of the present invention. FIG. 3 is a cross-sectional view showing a modified example of the connection structure.

Hereinafter, the details of the present invention will be described.

(Conductive material)
The conductive material according to the present invention contains a thermosetting component, a plurality of solder particles, and an additive having a relative permittivity of 30 or more. In the conductive material according to the present invention, an additive having a relative permittivity of 30 or more and a considerably high relative permittivity is used. In the conductive material according to the present invention, the content of the additive with respect to 100 parts by weight of the thermosetting component is 0.5 parts by weight or more and 10 parts by weight or less. In the conductive material according to the present invention, an additive having a considerably high relative permittivity is blended in a specific content.

Since the conductive material according to the present invention has the above-mentioned configuration, the solder particles can be efficiently arranged on the electrodes, and further, the occurrence of curing failure of the conductive material can be effectively suppressed. .. By using an additive having a relative permittivity of 30 or more, solder particles on the electrode are compared with the case where an additive having a relative permittivity of less than 30 (for example, a relative permittivity of 4 to 7) is used. Can be efficiently arranged, and further, the occurrence of curing defects of the conductive material can be effectively suppressed.

In a conductive material in which the solder particles are simply made smaller in diameter, it may not be possible to sufficiently aggregate the solder particles on the vertical electrodes to be connected at the time of conductive connection. Therefore, between the horizontal electrodes that should not be connected, the solder particles may remain as side balls or the like apart from the solder between the vertical electrodes. In addition, it may not be possible to sufficiently improve the conduction reliability between the electrodes to be connected and the insulation reliability between adjacent electrodes that should not be connected.

By using a specific additive, the present inventors suppress the electrostatic repulsive force between the solder particles at the time of conductive connection between the electrodes and improve the cohesiveness of the solder particles, thereby causing the solder particles on the electrodes. Was found to be able to be placed efficiently. In the present invention, despite the fact that the solder particles have a smaller particle size, the movement of the solder particles onto the electrodes proceeds sufficiently, and the solder can be efficiently arranged between the electrodes to be connected. It is possible to improve continuity reliability and insulation reliability.

Further, in the present invention, a plurality of solder particles are likely to gather between the upper and lower facing electrodes at the time of conductive connection between the electrodes, and the plurality of solder particles can be arranged on the electrodes (lines). Also, some of the plurality of solder particles are difficult to place between the lateral electrodes that should not be connected, and the amount of solder particles placed between the lateral electrodes that should not be connected can be significantly reduced. can. As a result, in the present invention, the residual amount of solder can be reduced between the lateral electrodes that must not be connected.

Further, in the present invention, since the solder particles can be efficiently aggregated on the electrode by using a specific additive, it is not necessary to excessively increase the flux content in the conductive material. As a result, the generation of voids in the cured product of the conductive material can be effectively suppressed, and the generation of poor curing of the conductive material can be effectively suppressed.

In the present invention, the use of a specific additive in order to obtain the above-mentioned effects greatly contributes.

Further, in the present invention, it is possible to prevent the positional deviation between the electrodes. In the present invention, when the second connection target member is superposed on the first connection target member on which the conductive material is arranged on the upper surface, the electrodes of the first connection target member and the electrodes of the second connection target member are aligned with each other. Even if the alignment is misaligned, the misalignment can be corrected and the electrodes can be connected to each other (self-alignment effect).

From the viewpoint of more efficiently arranging the solder on the electrodes, the conductive material is preferably liquid at 25 ° C., and is preferably a conductive paste.

From the viewpoint of more efficiently arranging the solder on the electrodes, the viscosity (η25) of the conductive material at 25 ° C. is preferably 20 Pa · s or more, more preferably 30 Pa · s or more, and preferably 400 Pa · s or more. -S or less, more preferably 300 Pa · s or less. The viscosity (η25) can be appropriately adjusted depending on the type and amount of the compounding component.

The viscosity (η25) can be measured at 25 ° C. and 5 rpm using, for example, an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.).

The gel fraction when the components excluding the solder particles in the conductive material are heated at 160 ° C. for 60 minutes is preferably 70% or more, more preferably 90% or more, preferably 100% or less, more preferably. It is 95% or less. When the gel fraction is not less than the lower limit and not more than the upper limit, the occurrence of curing failure of the conductive material can be suppressed more effectively.

The gel fraction is an index of curability of the conductive material. The higher the gel fraction, the better the curing of the conductive material.

The gel fraction can be measured as follows.

A curable composition is obtained by blending components excluding solder particles in the conductive material. The obtained curable composition is heated at 160 ° C. for 60 minutes while pressurizing at 1 MPa using a heating press to obtain a cured product having a thickness of 0.5 mm. Weigh 5 g of the obtained cured product and immerse it in 100 g of toluene at 25 ° C. for 20 hours. Then, the cured product is taken out, dried at 160 ° C. for 30 minutes, and the weight after drying is measured. The gel fraction can be calculated from the weight change before and after immersion in toluene by the following formula (1).

Gel fraction (%) = [Weight of cured product after toluene immersion (g) / Weight of cured product before toluene immersion (g)] × 100 ・ ・ ・ Equation (1)

The conductive material can be used as a conductive paste, a conductive film, or the like. The conductive paste is preferably an anisotropic conductive paste, and the conductive film is preferably an anisotropic conductive film. From the viewpoint of more efficiently arranging the solder on the electrodes, the conductive material is preferably a conductive paste. The conductive material is suitably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

Hereinafter, each component contained in the conductive material will be described. In addition, in this specification, "(meth) acrylic" means one or both of "acrylic" and "methacrylic".

(Solder particles)
The conductive material contains a plurality of solder particles. Both the central portion and the outer surface of the solder particles are formed of solder. The solder particles are particles in which both the central portion and the outer surface are solder. When conductive particles having a base particle formed of a material other than solder and a solder portion arranged on the surface of the base particle are used instead of the solder particles, the conductivity is on the electrode. It becomes difficult for particles to collect. Further, in the above-mentioned conductive particles, since the solder bondability between the conductive particles is low, the conductive particles that have moved on the electrodes tend to move easily to the outside of the electrodes, and the effect of suppressing the displacement between the electrodes is also obtained. Tends to be low.

The solder is preferably a metal having a melting point of 450 ° C. or lower (low melting point metal). The solder particles are preferably metal particles having a melting point of 450 ° C. or lower (low melting point metal particles). The low melting point metal particles are particles containing a low melting point metal. The low melting point metal means a metal having a melting point of 450 ° C. or lower. The melting point of the low melting point metal is preferably 300 ° C. or lower, more preferably 160 ° C. or lower. The solder particles are preferably low melting point solder having a melting point of less than 150 ° C.

The melting point of the solder particles can be determined by differential scanning calorimetry (DSC). Examples of the differential scanning calorimetry (DSC) device include "EXSTAR DSC7020" manufactured by SII.

Further, the solder particles preferably contain tin. The tin content in 100% by weight of the metal contained in the solder particles is preferably 30% by weight or more, more preferably 40% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight or more. .. When the tin content in the solder particles is at least the above lower limit, the connection reliability between the solder portion and the electrode becomes even higher.

The tin content may be determined using a high frequency inductively coupled plasma emission spectroscopic analyzer (“ICP-AES” manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer (“EDX-800HS” manufactured by Shimadzu Corporation). Can be measured.

By using the solder particles, the solder melts and is bonded to the electrodes, and the solder portion conducts the electrodes. For example, the solder portion and the electrode are likely to make surface contact rather than point contact, so that the connection resistance is low. Further, by using the solder particles, the bonding strength between the solder portion and the electrode is increased, and as a result, the peeling between the solder portion and the electrode is more difficult to occur, and the conduction reliability and the connection reliability are further improved.

The metal constituting the solder particles is not particularly limited. The metal is preferably tin or an alloy containing tin. Examples of the alloy include tin-silver alloy, tin-copper alloy, tin-silver-copper alloy, tin-bismuth alloy, tin-zinc alloy, tin-indium alloy and the like. The low melting point metal is preferably tin, tin-silver alloy, tin-silver-copper alloy, tin-bismuth alloy, or tin-indium alloy because of its excellent wettability to the electrode. More preferably, it is a tin-bismuth alloy or a tin-indium alloy.

The solder particles are preferably a filler material having a liquidus line of 450 ° C. or lower based on JIS Z3001: welding terminology. Examples of the composition of the solder particles include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. A tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic), which has a low melting point and is lead-free, is preferable. That is, the solder particles preferably do not contain lead, and preferably contain tin and indium, or preferably contain tin and bismuth.

In order to further increase the bonding strength between the solder part and the electrode, the solder particles are nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chrome, etc. It may contain a metal such as molybdenum or palladium. Further, from the viewpoint of further increasing the bonding strength between the solder portion and the electrode, the solder particles preferably contain nickel, copper, antimony, aluminum or zinc. From the viewpoint of further increasing the bonding strength between the solder portion and the electrode, the content of these metals for increasing the bonding strength is preferably 0.0001% by weight or more, preferably 1 weight in 100% by weight of the solder particles. % Or less.

The particle size of the solder particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more, and particularly preferably 5 μm or more. The particle size of the solder particles is preferably 100 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, still more preferably 20 μm or less, particularly preferably 15 μm or less, and most preferably 10 μm or less. When the particle diameter of the solder particles is not less than the lower limit and not more than the upper limit, the solder can be arranged more efficiently on the electrode. It is particularly preferable that the particle diameter of the solder particles is 5 μm or more and 30 μm or less.

The particle size of the solder particles is preferably an average particle size, and preferably a number average particle size. For the particle size of the solder particles, for example, observe 50 arbitrary solder particles with an electron microscope or an optical microscope, calculate the average value of the particle size of each solder particle, or perform laser diffraction type particle size distribution measurement. Demanded by.

The coefficient of variation (CV value) of the particle size of the solder particles is preferably 5% or more, more preferably 10% or more, preferably 40% or less, and more preferably 30% or less. When the coefficient of variation of the particle diameter of the solder particles is not less than the lower limit and not more than the upper limit, the solder can be arranged more uniformly on the electrode. However, the CV value of the particle diameter of the solder particles may be less than 5%.

The coefficient of variation (CV value) can be measured as follows.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of the particle size of the solder particles Dn: Mean value of the particle size of the solder particles

The shape of the solder particles is not particularly limited. The shape of the solder particles may be spherical or may be a shape other than a spherical shape such as a flat shape.

The content of the solder particles in 100% by weight of the conductive material is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, particularly preferably 20% by weight or more, and most preferably 30. It is 0% by weight or more, preferably 90% by weight or less, more preferably 80% by weight or less, still more preferably 70% by weight or less. When the content of the solder particles is not less than the above lower limit and not more than the above upper limit, it is easy to arrange the solder on the electrodes more efficiently, and the conduction reliability is further improved. From the viewpoint of further effectively enhancing the conduction reliability, it is preferable that the content of the solder particles is large.

(Thermosetting component)
The conductive material contains a thermosetting component. The conductive material may contain a thermosetting compound and a thermosetting agent as a thermosetting component. In order to increase the degree of curing of the conductive material, the conductive material preferably contains a thermosetting compound and a thermosetting agent as a thermosetting component. In order to increase the degree of curing of the conductive material, it is preferable that the conductive material contains a curing accelerator as a thermosetting component.

(Thermosetting component: Thermosetting compound)
The thermosetting compound is not particularly limited. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds and polyimide compounds. Epoxy compounds or episulfide compounds are preferable from the viewpoints of further improving the curability and viscosity of the conductive material, further effectively enhancing the conduction reliability, and further effectively enhancing the insulation reliability. Epoxy compounds are more preferred. The thermosetting compound preferably contains an epoxy compound. Only one type of the thermosetting compound may be used, or two or more types may be used in combination.

The epoxy compound is a compound having at least one epoxy group. Examples of the epoxy compound include bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, phenol novolac type epoxy compound, biphenyl type epoxy compound, biphenyl novolac type epoxy compound, biphenol type epoxy compound, and naphthalene type epoxy compound. , Fluolene type epoxy compound, phenol aralkyl type epoxy compound, naphthol aralkyl type epoxy compound, dicyclopentadiene type epoxy compound, anthracene type epoxy compound, epoxy compound with adamantan skeleton, epoxy compound with tricyclodecane skeleton, naphthylene ether type Examples thereof include an epoxy compound and an epoxy compound having a triazine nucleus as a skeleton. Only one kind of the epoxy compound may be used, or two or more kinds may be used in combination.

The epoxy compound is liquid or solid at room temperature (23 ° C.), and when the epoxy compound is solid at room temperature, the melting temperature of the epoxy compound is preferably equal to or lower than the melting point of the solder particles.

From the viewpoint of further improving the insulation reliability and the conduction reliability, the thermosetting compound preferably contains an epoxy compound.

From the viewpoint of further effectively enhancing the heat resistance of the cured product, the thermosetting compound preferably contains a thermosetting compound having an isocyanulu skeleton.

Examples of the thermosetting compound having an isocyanul skeleton include triisocyanurate type epoxy compounds, and TEPIC series (TEPIC-G, TEPIC-S, TEPIC-SS, TEPIC-HP, TEPIC-L, TEPIC-G, TEPIC-S, TEPIC-L, manufactured by Nissan Chemical Industries, Ltd. TEPIC-PAS, TEPIC-VL, TEPIC-UC) and the like.

The content of the thermosetting compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight or less. It is preferably 98% by weight or less, more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the thermosetting compound is not less than the above lower limit and not more than the above upper limit, the solder can be arranged more efficiently on the electrodes, and the insulation reliability between the electrodes can be further effectively improved. The conduction reliability between the electrodes can be further effectively improved. From the viewpoint of further effectively enhancing the impact resistance, it is preferable that the content of the thermosetting compound is large.

The content of the epoxy compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, preferably 99% by weight or less, more preferably 99% by weight or less. It is 98% by weight or less, more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the epoxy compound is equal to or higher than the lower limit and lower than the upper limit, the solder can be arranged more efficiently on the electrodes, the insulation reliability between the electrodes can be further improved, and the distance between the electrodes can be further improved. The continuity reliability of the solder can be further effectively improved. From the viewpoint of further enhancing the impact resistance, it is preferable that the content of the epoxy compound is large.

(Thermosetting component: Thermosetting agent)
The thermosetting agent is not particularly limited. The thermosetting agent heat-cures the thermosetting compound. Examples of the heat curing agent include thiol curing agents such as imidazole curing agents, amine curing agents, phenol curing agents, and polythiol curing agents, acid anhydride curing agents, thermal cation initiators (thermal cation curing agents), and thermal radical generators. Can be mentioned. Only one type of the thermosetting agent may be used, or two or more types may be used in combination.

From the viewpoint of enabling the conductive material to be cured more quickly at a low temperature, the thermal curing agent is preferably an imidazole curing agent, a thiol curing agent, or an amine curing agent. Further, from the viewpoint of enhancing the storage stability when the thermosetting compound and the thermosetting agent are mixed, the thermosetting agent is preferably a latent curing agent. The latent curing agent is preferably a latent imidazole curing agent, a latent thiol curing agent or a latent amine curing agent. The thermosetting agent may be coated with a polymer substance such as a polyurethane resin or a polyester resin.

The above-mentioned imidazole curing agent is not particularly limited. Examples of the imidazole curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, and 2,4-diamino-6. -[2'-Methylimidazolyl- (1')]-ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine isocyanuric acid adduct , 2-Phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2-palatoryl-4-methyl-5 5th position of 1H-imidazole in -hydroxymethylimidazole, 2-methtoluyl-4-methyl-5-hydroxymethylimidazole, 2-metatoluyl-4,5-dihydroxymethylimidazole, 2-paratoluyl-4,5-dihydroxymethylimidazole, etc. Examples thereof include an imidazole compound in which the hydrogen in the above is substituted with a hydroxymethyl group and the hydrogen at the 2-position is substituted with a phenyl group or a toluyl group.

The thiol curing agent is not particularly limited. Examples of the thiol curing agent include trimethylolpropanetris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate.

The amine curing agent is not particularly limited. Examples of the amine curing agent include hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5.5] undecane and bis (4). -Aminocyclohexyl) methane, metaphenylenediamine, diaminodiphenyl sulfone and the like.

The acid anhydride curing agent is not particularly limited, and any acid anhydride used as a curing agent for a thermosetting compound such as an epoxy compound can be widely used. Examples of the acid anhydride curing agent include phthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrochloride phthalic acid, hexahydrohydride phthalic acid, methylhexahydrohydride phthalic acid, methyltetrahydrohydride phthalic acid, and methylbutenyltetrahydrochloride phthalic acid. , Anhydride of phthalic acid derivative, maleic anhydride, nadic acid anhydride, methylnadic acid anhydride, glutaric anhydride, succinic anhydride, glycerinbis anhydrous trimellitic acid monoacetate, ethylene glycol bis anhydrous trimellitic acid, etc. Acid anhydride curing agent, trifunctional acid anhydride curing agent such as trimellitic anhydride, and pyromellitic anhydride, benzophenonetetracarboxylic acid anhydride, methylcyclohexenetetracarboxylic acid anhydride, polyazelineic acid anhydride, etc. Examples thereof include an acid anhydride curing agent having four or more functions.

The thermal cation initiator is not particularly limited. Examples of the thermal cation initiator include an iodonium-based cation curing agent, an oxonium-based cation curing agent, a sulfonium-based cation curing agent, and the like. Examples of the iodine-based cationic curing agent include bis (4-tert-butylphenyl) iodinenium hexafluorophosphate and the like. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium-based cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

The thermal radical generator is not particularly limited. Examples of the thermal radical generator include azo compounds and organic peroxides. Examples of the azo compound include azobisisobutyronitrile (AIBN) and the like. Examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

The reaction start temperature of the thermosetting agent is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, still more preferably 80 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, still more preferably 150 ° C. or higher. Below, it is particularly preferably 140 ° C. or lower. When the reaction start temperature of the thermosetting agent is equal to or higher than the lower limit and lower than the upper limit, the solder is more efficiently arranged on the electrode. The reaction start temperature of the thermosetting agent is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

From the viewpoint of more efficiently arranging the solder on the electrodes, the reaction start temperature of the thermosetting agent is preferably higher than the melting point of the solder in the solder particles, and more preferably 5 ° C. or higher. It is more preferable that the temperature is higher than ° C.

The reaction start temperature of the thermosetting agent means the temperature at which the exothermic peak starts to rise in the DSC.

The content of the thermosetting agent is not particularly limited. With respect to 100 parts by weight of the thermosetting compound, the content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, preferably 200 parts by weight or less, and more preferably. It is 100 parts by weight or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is at least the above lower limit, it is easy to sufficiently cure the conductive material. When the content of the thermosetting agent is not more than the above upper limit, it becomes difficult for the surplus thermosetting agent that was not involved in the curing to remain after curing, and the heat resistance of the cured product is further increased.

(Thermosetting component: Curing accelerator)
The conductive material may contain a curing accelerator. The curing accelerator is not particularly limited. The curing accelerator preferably acts as a curing catalyst in the reaction between the thermosetting compound and the thermosetting agent. The curing accelerator preferably acts as a curing catalyst in the reaction with the thermosetting compound. As the curing accelerator, only one kind may be used, or two or more kinds may be used in combination.

Examples of the curing accelerator include phosphonium salts, tertiary amines, tertiary amine salts, quaternary onium salts, tertiary phosphines, crown ether complexes, phosphonium ylides and the like. Specifically, the curing accelerator includes an imidazole compound, an isocyanurate of an imidazole compound, dicyandiamide, a derivative of dicyandiamide, a melamine compound, a derivative of a melamine compound, diaminomaleonitrile, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. , Amine compounds such as bis (hexamethylene) triamine, triethanolamine, diaminodiphenylmethane, organic acid dihydrazide, 1,8-diazabicyclo [5,4,0] undecene-7,3,9-bis (3-aminopropyl) Examples thereof include -2,4,8,10-tetraoxaspiro [5,5] undecane, boron trifluoride, and organic phosphorus compounds such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine and methyldiphenylphosphine.

The phosphonium salt is not particularly limited. Examples of the phosphonium salt include tetranormal butyl phosphonium bromide, tetranormal butyl phosphonium O-O diethyl dithiophosphate, methyl tributyl phosphonium dimethyl phosphate, tetranormal butyl phosphonium benzotriazole, tetranormal butyl phosphonium tetrafluoroborate, and tetranormal butyl. Examples thereof include phosphonium tetraphenylborate.

The content of the curing accelerator is appropriately selected so that the thermosetting compound can be cured well. The content of the curing accelerator with respect to 100 parts by weight of the thermosetting compound is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, preferably 10 parts by weight or less, and more preferably 8 parts by weight. It is less than the weight part. When the content of the curing accelerator is at least the above lower limit and at least the above upper limit, the thermosetting compound can be satisfactorily cured.

(Additive)
The conductive material contains an additive having a relative permittivity of 30 or more. From the viewpoint of more efficiently arranging the solder particles on the electrodes and more effectively suppressing the occurrence of curing defects of the conductive material, the relative permittivity of the additive is preferably 35 or more. It is preferably 40 or more. The upper limit of the relative permittivity of the additive is not particularly limited. The relative permittivity of the additive may be 4000 or less, or 2000 or less.

The relative permittivity of the additive can be calculated by measuring the permittivity of the additive using a dielectric measuring device (Solartron 1296, manufactured by Toyo Corporation). The dielectric constant of the additive is measured under the conditions of applied voltage: 100 mVAC and frequency: 1 MHz to 1 Hz.

The additive is not particularly limited as long as it is an additive that satisfies the above-mentioned preferable range of the relative permittivity. The additive may be a flux described later, or may be a formulation different from the flux described later. Only one kind of the above-mentioned additive may be used, or two or more kinds thereof may be used in combination.

Examples of the additive include glycerin, formic acid, croconic acid, Rochelle salt and the like. From the viewpoint of more efficiently arranging the solder particles on the electrode and more effectively suppressing the occurrence of curing failure of the conductive material, the above-mentioned additive is glycerin, formic acid, croconic acid, or Rochelle salt. Is preferable, and glycerin or formic acid is more preferable.

The content of the additive with respect to 100 parts by weight of the thermosetting component is 0.5 parts by weight or more and 10 parts by weight or less. The content of the additive with respect to 100 parts by weight of the thermosetting component is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, preferably 10 parts by weight or less, and more preferably 5 parts by weight or less. Is. When the content of the additive with respect to 100 parts by weight of the thermosetting component is not less than the lower limit and not more than the upper limit, the solder particles can be arranged more efficiently on the electrode, and the conductive material is poorly cured. Can be suppressed even more effectively.

The content of the additive in 100% by weight of the conductive material is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, preferably 3% by weight or less, and more preferably 1.5% by weight. % Or less. When the content of the additive in 100% by weight of the conductive material is not less than the above lower limit and not more than the above upper limit, the solder particles can be arranged more efficiently on the electrode, and the conductive material is poorly cured. Can be suppressed even more effectively.

(flux)
The conductive material may contain a flux. The relative permittivity of this flux may be less than 30. By using the flux, the solder can be placed more efficiently on the electrodes. The above flux is not particularly limited. As the flux, a flux generally used for solder bonding or the like can be used. The flux may be the additive described above.

The flux includes zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, a hydrazine, an amine compound, an organic acid and the like. Examples include pine fat. Only one kind of the above flux may be used, or two or more kinds of the flux may be used in combination.

Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamate and glutaric acid. Examples of the pine fat include activated pine fat and deactivated pine fat. The flux is preferably an organic acid having two or more carboxyl groups or pine fat. The flux may be an organic acid having two or more carboxyl groups, or may be pine fat. The use of organic acids and pine fats having two or more carboxyl groups further enhances the reliability of conduction between the electrodes.

Examples of the organic acid having two or more carboxyl groups include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

Examples of the amine compound include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzoimidazole, benzotriazole, and carboxybenzotriazole.

The above-mentioned pine fat is a rosin containing abietic acid as a main component. Examples of the rosins include abietic acid and acrylic-modified rosins. The flux is preferably rosins, more preferably abietic acid. By using this preferable flux, the conduction reliability between the electrodes is further increased.

The active temperature (melting point) of the flux is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, still more preferably 80 ° C. or higher, preferably 200 ° C. or lower, more preferably 190 ° C. or lower, still more preferably 160 ° C. or higher. ° C. or lower, more preferably 150 ° C. or lower, even more preferably 140 ° C. or lower. When the active temperature of the flux is not less than the lower limit and not more than the upper limit, the flux effect is exhibited more effectively and the solder is arranged more efficiently on the electrode. The active temperature (melting point) of the flux is preferably 80 ° C. or higher and 190 ° C. or lower. The active temperature (melting point) of the flux is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

The active temperature (melting point) of the flux is 80 ° C. or higher and 190 ° C. or lower. 104 ° C.), dicarboxylic acids such as suberic acid (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), malic acid (melting point 130 ° C.) and the like.

Further, the boiling point of the flux is preferably 200 ° C. or lower.

From the viewpoint of more efficiently arranging the solder on the electrodes, the melting point of the flux is preferably higher than the melting point of the solder particles, more preferably 5 ° C or higher, and further preferably 10 ° C or higher. preferable.

From the viewpoint of more efficiently arranging the solder on the electrode, the melting point of the flux is preferably higher than the reaction start temperature of the thermosetting agent, more preferably 5 ° C or higher, and 10 ° C or higher. Is even more preferable.

The flux may be dispersed in the conductive material or may be attached to the surface of the solder particles.

Since the melting point of the flux is higher than the melting point of the solder particles, the solder particles can be efficiently aggregated on the electrode portion. This is because, when heat is applied at the time of joining, when the electrode formed on the connection target member and the connection target member portion around the electrode are compared, the thermal conductivity of the electrode portion is that of the connection target member portion around the electrode. Because it is higher than the thermal conductivity, the temperature rise of the electrode portion is fast. At the stage where the melting point of the solder particles is exceeded, the inside of the solder particles is melted, but the oxide film formed on the surface is not removed because it has not reached the melting point (active temperature) of the flux. In this state, since the temperature of the electrode portion reaches the melting point (active temperature) of the flux first, the oxide film on the surface of the solder particles that has preferentially moved onto the electrode is removed, and the solder particles are placed on the surface of the electrode. It can spread wet. As a result, the solder particles can be efficiently aggregated on the electrode.

The flux is preferably a flux that releases cations by heating. The use of a flux that releases cations upon heating allows the solder to be placed more efficiently on the electrodes.

Examples of the flux that releases cations by heating include the thermal cation initiator (thermal cation curing agent).

From the viewpoint of arranging the solder on the electrodes more efficiently, improving the insulation reliability more effectively, and further improving the conduction reliability, the above flux is an acid compound and a base compound. It is preferably a salt of.

The acid compound is preferably an organic compound having a carboxyl group. Examples of the acid compound include malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, citric acid, malic acid, and cyclic aliphatic carboxylic acid, which are aliphatic carboxylic acids. Examples thereof include cyclohexylcarboxylic acid, 1,4-cyclohexyldicarboxylic acid, aromatic carboxylic acids isophthalic acid, terephthalic acid, trimellitic acid, ethylenediamine tetraacetic acid and the like. From the viewpoint of arranging the solder more efficiently on the electrodes, further improving the insulation reliability, and further effectively improving the conduction reliability, the acid compounds are glutaric acid and cyclohexyl. It is preferably a carboxylic acid or an adipic acid.

The basic compound is preferably an organic compound having an amino group. Examples of the basic compound include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, and 4-tert-butylbenzylamine. , N-Methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N, N-dimethylbenzylamine, imidazole compounds, and triazole compounds. .. From the viewpoint of more efficiently arranging the solder on the electrode, further effectively enhancing the insulation reliability, and further effectively enhancing the conduction reliability, the basic compound is benzylamine. Is preferable.

The content of the flux in 100% by weight of the conductive material is preferably 0.5% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. The conductive material may not contain flux. When the content of the flux is not less than the above lower limit and not more than the above upper limit, it becomes more difficult to form an oxide film on the surface of the solder and the electrode, and further, the oxide film formed on the surface of the solder and the electrode is further formed. Can be effectively removed.

(Filler)
The conductive material according to the present invention may contain a filler. The filler may be an organic filler or an inorganic filler. When the conductive material contains a filler, the solder particles can be uniformly aggregated on all the electrodes of the substrate.

The conductive material preferably does not contain the filler or contains the filler in an amount of 5% by weight or less. When the thermosetting compound is used, the smaller the filler content, the easier it is for the solder particles to move onto the electrodes.

The content of the filler in 100% by weight of the conductive material is preferably 0% by weight (not contained) or more, preferably 5% by weight or less, more preferably 2% by weight or less, still more preferably 1% by weight or less. be. When the content of the filler is not less than the lower limit and not more than the upper limit, the solder is more evenly arranged on the electrode.

(Other ingredients)
The conductive material may be, for example, a filler, a bulking agent, a softener, a plasticizer, a thixo agent, a leveling agent, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, or a light stabilizer, if necessary. , UV absorbers, lubricants, antistatic agents, flame retardants and the like.

(Connection structure and manufacturing method of connection structure)
The connection structure according to the present invention includes a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, and the first connection target member. It includes a connecting portion that connects to the second connection target member. In the connection structure according to the present invention, the material of the connection portion is the above-mentioned conductive material. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

The method for manufacturing a connection structure according to the present invention includes a step of arranging the conductive material on the surface of a first connection target member having a first electrode on the surface by using the above-mentioned conductive material. In the method for manufacturing a connection structure according to the present invention, a second connection target member having a second electrode on the surface of the conductive material opposite to the first connection target member side is provided on the surface of the conductive material. A step of arranging the electrode 1 and the second electrode so as to face each other is provided. In the method for manufacturing a connection structure according to the present invention, the conductive material is heated above the melting point of the solder particles to connect the first connection target member and the second connection target member. The portion is formed of the conductive material, and the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

In the connection structure and the method for manufacturing the connection structure according to the present invention, since a specific conductive material is used, the solder particles are likely to collect between the first electrode and the second electrode, and the solder particles are used as electrodes ( Can be efficiently placed on the line). Further, it is difficult for a part of the solder particles to be arranged in the region (space) where the electrode is not formed, and the amount of the solder particles arranged in the region where the electrode is not formed can be considerably reduced. Therefore, the conduction reliability between the first electrode and the second electrode can be improved. Moreover, it is possible to prevent electrical connection between horizontally adjacent electrodes that should not be connected, and it is possible to improve insulation reliability.

Further, in order to efficiently arrange the solder on the electrodes and to considerably reduce the amount of the solder arranged in the region where the electrodes are not formed, the conductive material uses a conductive paste instead of a conductive film. Is preferable.

The thickness of the solder portion between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, preferably 100 μm or less, and more preferably 80 μm or less. The solder wet area on the surface of the electrode (the area in contact with the solder in the exposed area of the electrode) is preferably 50% or more, more preferably 70% or more, and preferably 100% or less.

In the method for manufacturing a connection structure according to the present invention, no pressurization is performed in the step of arranging the second connection target member and the step of forming the connection portion, and the conductive material is connected to the second connection. It is preferable that the weight of the target member is added. In the method for manufacturing a connection structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection portion, the conductive material is subjected to the force of the weight of the second connection target member. It is preferable that no pressurizing pressure exceeding the above is applied. In these cases, the uniformity of the soldering amount can be further improved in the plurality of soldered portions. Furthermore, the thickness of the solder portion can be increased more effectively, a large number of solder particles can easily gather between the electrodes, and the plurality of solder particles can be arranged more efficiently on the electrodes (lines). can. Further, it is difficult for some of the plurality of solder particles to be arranged in the region (space) where the electrodes are not formed, and the amount of solder in the solder particles arranged in the region where the electrodes are not formed can be further reduced. can. Therefore, the continuity reliability between the electrodes can be further improved. Moreover, it is possible to further prevent electrical connection between electrodes adjacent in the lateral direction that should not be connected, and it is possible to further improve insulation reliability.

Further, if a conductive paste is used instead of the conductive film, it becomes easy to adjust the thickness of the connecting portion and the solder portion depending on the amount of the conductive paste applied. On the other hand, in the case of the conductive film, in order to change or adjust the thickness of the connecting portion, it is necessary to prepare a conductive film having a different thickness or a conductive film having a predetermined thickness. There is. Further, in the conductive film, the melt viscosity of the conductive film cannot be sufficiently lowered at the melting temperature of the solder as compared with the conductive paste, and the aggregation of the solder particles tends to be hindered.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained by using the conductive material according to the embodiment of the present invention.

The connection structure 1 shown in FIG. 1 is a connection connecting the first connection target member 2, the second connection target member 3, the first connection target member 2, and the second connection target member 3. A unit 4 is provided. The connecting portion 4 is formed of the above-mentioned conductive material. In the present embodiment, the conductive material contains a thermosetting component, solder particles, and an additive. The thermosetting component contains a thermosetting compound and a thermosetting agent. In this embodiment, a conductive paste is used as the conductive material.

The connecting portion 4 has a solder portion 4A in which a plurality of solder particles are gathered and bonded to each other, and a cured product portion 4B in which a thermosetting compound is thermally cured.

The first connection target member 2 has a plurality of first electrodes 2a on the surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by the solder portion 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by the solder portion 4A. In the connecting portion 4, the solder particles do not exist in the region (cured product portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In the region different from the solder portion 4A (cured product portion 4B portion), there are no solder particles separated from the solder portion 4A. If the amount is small, the solder particles may be present in a region (cured product portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a.

As shown in FIG. 1, in the connection structure 1, a plurality of solder particles are gathered between the first electrode 2a and the second electrode 3a, and after the plurality of solder particles are melted, the melt of the solder particles is formed. The surface of the electrode is wet and spread, and then solidified to form the solder portion 4A. Therefore, the connection area between the solder portion 4A and the first electrode 2a and the solder portion 4A and the second electrode 3a becomes large. That is, by using the solder particles, the solder portion 4A, the first electrode 2a, and the solder portion are compared with the case where the conductive outer surface is made of a metal such as nickel, gold, or copper. The contact area between the 4A and the second electrode 3a becomes large. This also increases the continuity reliability and connection reliability of the connection structure 1. When the conductive material contains a flux, the flux is generally gradually inactivated by heating.

In the connection structure 1 shown in FIG. 1, all of the solder portions 4A are located in facing regions between the first and second electrodes 2a and 3a. In the connection structure 1X of the modified example shown in FIG. 3, only the connection portion 4X is different from the connection structure 1 shown in FIG. The connection portion 4X has a solder portion 4XA and a cured product portion 4XB. Like the connection structure 1X, most of the solder portions 4XA are located in the facing regions of the first and second electrodes 2a and 3a, and a part of the solder portions 4XA is the first and second electrodes. The electrodes 2a and 3a may protrude laterally from the facing regions. The solder portion 4XA protruding laterally from the facing regions of the first and second electrodes 2a and 3a is a part of the solder portion 4XA and is not a solder particle separated from the solder portion 4XA. In this embodiment, the amount of solder particles separated from the solder portion can be reduced, but the solder particles separated from the solder portion may be present in the cured product portion.

If the amount of solder particles used is reduced, it becomes easy to obtain the connection structure 1. If the amount of solder particles used is increased, it becomes easy to obtain the connection structure 1X.

In the connection structures 1, 1X, when the portions facing each other of the first electrode 2a and the second electrode 3a are seen in the stacking direction of the first electrode 2a, the connection portions 4, 4X, and the second electrode 3a. It is preferable that the solder portions 4A and 4XA in the connecting portions 4 and 4X are arranged in 50% or more of the area of 100% of the portions facing each other of the first electrode 2a and the second electrode 3a. .. When the solder portions 4A and 4XA in the connection portions 4 and 4X satisfy the above-mentioned preferable embodiments, the continuity reliability can be further improved.

When the portions facing each other of the first electrode and the second electrode are seen in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode are seen. It is preferable that the solder portion in the connection portion is arranged in 50% or more of the area of 100% of the portions facing the electrodes of 2. When the portions facing each other of the first electrode and the second electrode are seen in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode are seen. It is more preferable that the solder portion in the connection portion is arranged in 60% or more of the area of 100% of the portions facing the electrodes of 2. When the portions facing each other of the first electrode and the second electrode are seen in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode are seen. It is more preferable that the solder portion in the connection portion is arranged in 70% or more of the area of 100% of the portions facing the electrodes of 2. When the portions facing each other of the first electrode and the second electrode are seen in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode are seen. It is particularly preferable that the solder portion in the connection portion is arranged in 80% or more of the area of 100% of the portions facing the electrodes of 2. When the portions facing each other of the first electrode and the second electrode are seen in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode are seen. It is most preferable that the solder portion in the connection portion is arranged in 90% or more of the area of 100% of the portions facing the electrodes of 2. When the solder portion in the connection portion satisfies the above-mentioned preferable embodiment, the continuity reliability can be further improved.

When the portion where the first electrode and the second electrode face each other is seen in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode is used. It is preferable that 60% or more of the solder portion in the connection portion is arranged at the portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other is seen in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode is used. It is more preferable that 70% or more of the solder portion in the connection portion is arranged at the portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other is seen in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode is used. It is more preferable that 90% or more of the solder portion in the connection portion is arranged at the portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other is seen in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode is used. It is particularly preferable that 95% or more of the solder portion in the connection portion is arranged at the portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other is seen in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode is used. It is most preferable that 99% or more of the solder portion in the connection portion is arranged at the portion where the electrode and the second electrode face each other. When the solder portion in the connection portion satisfies the above-mentioned preferable embodiment, the continuity reliability can be further improved.

Next, FIG. 2 describes an example of a method for manufacturing the connection structure 1 using the conductive material according to the embodiment of the present invention.

First, the first connection target member 2 having the first electrode 2a on the surface (upper surface) is prepared. Next, as shown in FIG. 2A, the conductive material 11 containing the thermosetting component 11B and the plurality of solder particles 11A is arranged on the surface of the first connection target member 2 (first). Process). The conductive material 11 used contains a thermosetting compound and a thermosetting agent as the thermosetting component 11B. The conductive material 11 used contains an additive.

The conductive material 11 is arranged on the surface of the first connection target member 2 on which the first electrode 2a is provided. After the arrangement of the conductive material 11, the solder particles 11A are arranged both on the first electrode 2a (line) and on the region (space) where the first electrode 2a is not formed.

The method of arranging the conductive material 11 is not particularly limited, and examples thereof include coating with a dispenser, screen printing, and ejection with an inkjet device.

Further, a second connection target member 3 having the second electrode 3a on the surface (lower surface) is prepared. Next, as shown in FIG. 2B, in the conductive material 11 on the surface of the first connection target member 2, on the surface of the conductive material 11 opposite to the first connection target member 2 side. The second connection target member 3 is arranged (second step). The second connection target member 3 is arranged on the surface of the conductive material 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

Next, the conductive material 11 is heated above the melting point of the solder particles 11A (third step). Preferably, the conductive material 11 is heated above the curing temperature of the thermosetting component 11B (thermosetting compound). At the time of this heating, the solder particles 11A existing in the region where the electrodes are not formed gather between the first electrode 2a and the second electrode 3a (self-aggregating effect). When a conductive paste is used instead of the conductive film, the solder particles 11A are more effectively collected between the first electrode 2a and the second electrode 3a. Further, the solder particles 11A are melted and bonded to each other. Further, the thermosetting component 11B is thermoset. As a result, as shown in FIG. 2C, the connecting portion 4 connecting the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. The connecting portion 4 is formed by the conductive material 11, the solder portion 4A is formed by joining the plurality of solder particles 11A, and the cured product portion 4B is formed by thermally curing the thermosetting component 11B. If the solder particles 11A move sufficiently, the solder particles 11A that are not located between the first electrode 2a and the second electrode 3a start to move, and then the first electrode 2a and the second electrode 2a and the second electrode It is not necessary to keep the temperature constant until the movement of the solder particles 11A to and from 3a is completed.

In the present embodiment, it is preferable not to pressurize in the second step and the third step. In this case, the weight of the second connection target member 3 is added to the conductive material 11. Therefore, when the connecting portion 4 is formed, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. When pressure is applied in at least one of the second step and the third step, the solder particles 11A tend to gather between the first electrode 2a and the second electrode 3a. Is more likely to be inhibited.

Further, in the present embodiment, since the pressurization is not performed, the first connection target member 2 and the second connection target member 3 are in a state where the first electrode 2a and the second electrode 3a are out of alignment. Even when and are overlapped with each other, the deviation can be corrected and the first electrode 2a and the second electrode 3a can be connected (self-alignment effect). This is because the molten solder that is self-aggregated between the first electrode 2a and the second electrode 3a is the solder between the first electrode 2a and the second electrode 3a and other conductive materials. This is because the one where the area in contact with the component is the minimum is energetically stable, and the force for making the connected structure with alignment, which is the connection structure with the minimum area, works. At this time, it is desirable that the conductive material is not cured and that the viscosity of the components other than the solder particles of the conductive material is sufficiently low at the temperature and time.

The viscosity of the conductive material at the melting point of the solder particles is preferably 50 Pa · s or less, more preferably 10 Pa · s or less, still more preferably 1 Pa · s or less, preferably 0.1 Pa · s or more, and more preferably 0. .2 Pa · s or more. When the viscosity is not more than the upper limit, the solder particles can be efficiently aggregated. When the viscosity is at least the above lower limit, voids at the connecting portion can be suppressed, and the protrusion of the conductive material to other than the connecting portion can be suppressed.

For the viscosity of the conductive material at the melting point of the solder particles, strain control 1 rad, frequency 1 Hz, temperature rise rate 20 ° C./min, measurement temperature range 25 to 200 ° C. (however, solder) using STRESSTECH (manufactured by REOLOGICA) or the like. When the melting point of the particles exceeds 200 ° C., the upper limit of the temperature is taken as the melting point of the solder particles). From the measurement results, the viscosity of the solder particles at the melting point (° C) is evaluated.

In this way, the connection structure 1 shown in FIG. 1 is obtained. The second step and the third step may be continuously performed. Further, after performing the second step, the obtained laminate of the first connection target member 2, the conductive material 11 and the second connection target member 3 is moved to the heating unit, and the third The process may be performed. In order to perform the heating, the laminate may be arranged on the heating member, or the laminate may be arranged in the heated space.

The heating temperature in the third step is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, preferably 450 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower.

As a heating method in the third step, a method of heating the entire connection structure using a reflow furnace or an oven at a temperature equal to or higher than the melting point of the solder particles and a temperature higher than the curing temperature of the thermosetting component, or a connection structure. A method of locally heating only the connection part of the body can be mentioned.

Examples of the appliance used for the method of locally heating include a hot plate, a heat gun for applying hot air, a soldering iron, an infrared heater, and the like.

When locally heating on a hot plate, use a metal with high thermal conductivity directly under the connection, and use a material with low thermal conductivity such as fluororesin in other areas where heating is not preferable. , It is preferable to form the upper surface of the hot plate.

The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors and diodes, resin films, printed circuit boards, flexible printed circuit boards, and flexible devices. Examples thereof include electronic components such as flat cables, rigid flexible boards, glass epoxy boards, circuit boards such as glass boards, and the like. The first and second connection target members are preferably electronic components.

It is preferable that at least one of the first connection target member and the second connection target member is a resin film, a flexible printed substrate, a flexible flat cable, or a rigid flexible substrate. It is preferable that the second connection target member is a resin film, a flexible printed substrate, a flexible flat cable, or a rigid flexible substrate. Resin films, flexible printed substrates, flexible flat cables and rigid flexible substrates have the properties of high flexibility and relatively light weight. When a conductive film is used for connecting such a member to be connected, solder particles tend to be difficult to collect on the electrodes. On the other hand, by using the conductive paste, even if a resin film, a flexible printed substrate, a flexible flat cable or a rigid flexible substrate is used, the solder particles are efficiently collected on the electrodes, so that the conduction between the electrodes is reliable. The sex can be sufficiently enhanced. When a resin film, flexible printed substrate, flexible flat cable, or rigid flexible substrate is used, the conduction reliability between the electrodes due to no pressurization is higher than when other connected members such as semiconductor chips are used. The improvement effect can be obtained even more effectively.

Examples of the electrodes provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the connection target member is a flexible printed substrate, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode formed only of aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al and Ga.

In the connection structure according to the present invention, it is preferable that the first electrode and the second electrode are arranged by an area array or a peripheral. When the first electrode and the second electrode are arranged in an area array or a peripheral, the effect of the present invention is more effectively exhibited. The area array is a structure in which the electrodes are arranged in a grid pattern on the surface on which the electrodes of the members to be connected are arranged. The peripheral is a structure in which electrodes are arranged on the outer peripheral portion of a member to be connected. In the case of a structure in which the electrodes are arranged in a comb shape, the solder particles may be aggregated along the direction perpendicular to the comb, whereas in the area array or the peripheral structure, the entire surface on the surface where the electrodes are arranged. It is necessary that the solder particles are uniformly aggregated in. Therefore, in the conventional method, the amount of solder tends to be non-uniform, whereas in the method of the present invention, the effect of the present invention is more effectively exhibited.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

Thermosetting component (thermosetting compound):
Thermosetting compound 1: Phenol novolac type epoxy compound, "DEN431" manufactured by DOWN
Thermosetting compound 2: Bisphenol A type epoxy compound, "YD-8125" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Thermosetting compound 3: Bisphenol F type epoxy compound, "YDF-8170C" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.

Thermosetting component (thermosetting agent):
Thermosetting agent 1: Acid anhydride curing agent, "Ricacid TH" manufactured by Shin Nihon Rika Co., Ltd.

Thermosetting component (curing accelerator):
Curing Accelerator 1: Boron Trifluoride, "Boron Trifluoride Ethylamine Complex" manufactured by Aldrich
Curing accelerator 2: Organic phosphonium salt, "PX-4MP" manufactured by Nippon Chemical Industrial Co., Ltd.
Curing accelerator 3: Organic phosphonium salt, "PX-4B" manufactured by Nippon Chemical Industrial Co., Ltd.
Curing accelerator 4: Organic phosphonium salt, "PX-4ET" manufactured by Nippon Chemical Industrial Co., Ltd.
Curing accelerator 5: Organic phosphonium salt, "PX-4BT" manufactured by Nippon Chemical Industrial Co., Ltd.

flux:
Flux 1: "Glutaric acid benzylamine salt", melting point 108 ° C

Method for producing flux 1:
In a glass bottle, 24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were put and dissolved at room temperature until uniform. Then, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for about 5 minutes to obtain a mixed solution. The obtained mixed solution was placed in a refrigerator at 5 to 10 ° C. and left overnight. The precipitated crystals were separated by filtration, washed with water and vacuum dried to obtain flux 1.

Additive:
Additive 1: Glycerin, "glycerol" manufactured by Tokyo Chemical Industry Co., Ltd., relative permittivity: 47
Additive 2: Formic acid, "Formic acid" manufactured by Tokyo Chemical Industry Co., Ltd., Relative permittivity: 58.5
Additive 3: Croconic acid, "croconic acid" manufactured by Tokyo Chemical Industry Co., Ltd., relative permittivity: 2000
Additive 4: Rochelle salt, Tokyo Chemical Industry Co., Ltd. "L- (+)-potassium sodium tartrate tetrahydrate", relative permittivity: 4000
Additive 5: Phenol, "Phenol" manufactured by Tokyo Chemical Industry Co., Ltd., Relative permittivity: 10

Solder particles:
Solder particles 1: SnBi solder particles, melting point 138 ° C, solder particles selected from "Sn42Bi58" manufactured by Mitsui Mining & Smelting Co., Ltd., average particle diameter: 15 μm
Solder particles 2: SnBi solder particles, melting point 138 ° C, solder particles selected from "Sn42Bi58" manufactured by Mitsui Mining & Smelting Co., Ltd., average particle diameter: 10 μm

(Relative permittivity of additives)
The relative permittivity of the additive was calculated by measuring the permittivity of the additive using a dielectric measuring device (Solartron 1296, manufactured by Toyo Corporation). The dielectric constant of the additive was measured under the conditions of applied voltage: 100 mVAC and frequency: 1 MHz to 1 Hz.

(Examples 1 to 19 and Comparative Examples 1 to 6)
(1) Preparation of Conductive Material (Anisotropic Conductive Paste) The components shown in Tables 1 and 2 below are blended in the blending amounts shown in Tables 1 and 2 below to obtain a conductive material (anisotropic conductive paste). rice field.

(2) Preparation of Connection Structure As the first connection target member, a glass poxi substrate having a copper electrode with L / S = 250 μm / 150 μm on the surface was prepared.

As the second connection target member, a semiconductor chip having a copper electrode having L / S = 250 μm / 150 μm on the surface was prepared.

A conductive material (anisotropic conductive paste) immediately after production was applied to the upper surface of the glass epoxy substrate so as to have a thickness of 100 μm to form a conductive material (anisotropic conductive paste) layer. Next, semiconductor chips were laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes face each other. The weight of the semiconductor chip is added to the conductive material (anisotropic conductive paste) layer. From that state, the temperature of the conductive material (anisotropic conductive paste) layer was heated so as to reach the melting point of the solder 5 seconds after the start of temperature rise. Further, 15 seconds after the start of temperature rise, the conductive material (anisotropic conductive paste) layer is heated to 160 ° C. to cure the conductive material (anisotropic conductive paste) layer, and the connection structure is formed. Obtained. No pressurization was performed during heating.

(evaluation)
(1) Solder side ball In the obtained connection structure, by observing the connection portion with a scanning electron microscope, it was confirmed whether or not the solder side ball was formed around the connection portion. The solder side balls were judged according to the following criteria.

[Solder side ball criteria]
○ ○: The number of solder side balls formed around the connection part is 5 or less ○: The number of solder side balls formed around the connection part exceeds 6 and is 15 or less ×: Connection part The number of solder side balls formed around the is more than 16

(2) Precision of solder placement on the electrodes In the obtained connection structure, the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the portion, the ratio Y of the area where the solder portion in the connecting portion is arranged in the area of 100% of the portion where the first electrode and the second electrode face each other was evaluated. The accuracy of solder placement on the electrodes was judged according to the following criteria.

[Criteria for determining the accuracy of solder placement on electrodes]
○ ○: Ratio Y is 70% or more ○: Ratio Y is 60% or more and less than 70% Δ: Ratio Y is 50% or more and less than 60% ×: Ratio Y is less than 50%

(3) Conduction reliability between the upper and lower electrodes In the obtained connection structure (n = 15 pieces), the connection resistance per connection point between the upper and lower electrodes was measured by the 4-terminal method. The average value of the connection resistance was calculated. From the relationship of voltage = current × resistance, the connection resistance can be obtained by measuring the voltage when a constant current is passed. The continuity reliability was judged according to the following criteria.

[Criteria for continuity reliability]
○ ○: The average value of the connection resistance is 50 mΩ or less ○: The average value of the connection resistance exceeds 50 mΩ and 70 mΩ or less △: The average value of the connection resistance exceeds 70 mΩ and 100 mΩ or less ×: The average value of the connection resistance exceeds 100 mΩ Or there is a poor connection

(4) Insulation reliability between adjacent electrodes In the obtained connection structure (n = 15 pieces), after leaving it in an atmosphere of 85 ° C. and humidity of 85% for 100 hours, 5V is applied between the adjacent electrodes. , The resistance value was measured at 25 points. The insulation reliability was judged according to the following criteria.

[Criteria for insulation reliability]
○ ○: Mean value of connection resistance is 107 Ω or more ○: Mean value of connection resistance is 10 ⁶ Ω or more and less than 10 ⁷ Ω △: Mean value of connection resistance is ¹⁰⁵ Ω or more and less than ^{10 6 Ω} ×: Connection Mean resistance is less than ¹⁰⁵ Ω

(5) Gel fraction Among the components shown in Tables 1 and 2 below, components excluding solder particles were blended to obtain a curable composition. The obtained curable composition was heated at 160 ° C. for 60 minutes while pressurizing at 1 MPa using a heating press to obtain a cured product having a thickness of 0.5 mm. 5 g of the obtained cured product was weighed and immersed in 100 g of toluene at 25 ° C. for 20 hours. Then, the cured product was taken out, dried at 160 ° C. for 30 minutes, and the weight of the dried product was measured. The gel fraction was calculated by the following formula (1) from the weight change before and after immersion in toluene. The gel fraction was determined according to the following criteria.

Gel fraction (%) = [Weight of cured product after toluene immersion (g) / Weight of cured product before toluene immersion (g)] × 100 ・ ・ ・ Equation (1)

[Criteria for gel fraction]
○ ○: Gel fraction is 90% or more and 100% or less ○: Gel fraction is 70% or more and less than 90% ×: Gel fraction is less than 70%

The results are shown in Tables 1 and 2 below.

The same tendency was observed when a flexible printed substrate, a resin film, a flexible flat cable, and a rigid flexible substrate were used.

1,1X ... Connection structure 2 ... First connection target member 2a ... First electrode 3 ... Second connection target member 3a ... Second electrode 4,4X ... Connection part 4A, 4XA ... Solder part 4B, 4XB … Cured material part 11… Conductive material 11A… Solder particles 11B… Thermosetting component

Claims (9)

It contains a thermosetting component, a plurality of solder particles, and an additive having a relative permittivity of 30 or more.
A conductive material in which the content of the additive with respect to 100 parts by weight of the thermosetting component is 0.5 parts by weight or more and 10 parts by weight or less. The conductive material according to claim 1, wherein the content of the additive is 0.1% by weight or more and 3% by weight or less in 100% by weight of the conductive material. The conductive material according to claim 1 or 2, which comprises a flux. The conductivity according to any one of claims 1 to 3, wherein the gel component in the conductive material excluding the solder particles is 70% or more and 100% or less when heated at 160 ° C. for 60 minutes. material. The conductive material according to any one of claims 1 to 4, which is a conductive paste. A first connection target member having a first electrode on its surface,
A second connection target member having a second electrode on the surface,
The first connection target member and the connection portion connecting the second connection target member are provided.
The material of the connection portion is the conductive material according to any one of claims 1 to 5.
A connection structure in which the first electrode and the second electrode are electrically connected by a solder portion in the connection portion. When the portions facing each other of the first electrode and the second electrode are seen in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the first electrode are seen. The connection structure according to claim 6, wherein the solder portion in the connection portion is arranged in 50% or more of the area of 100% of the portions facing the electrodes of 2. A step of arranging the conductive material on the surface of a first connection target member having a first electrode on the surface using the conductive material according to any one of claims 1 to 5.
The first electrode and the second electrode face each other on the surface of the conductive material opposite to the first connection target member side, with the second connection target member having the second electrode on the surface. And the process of arranging
By heating the conductive material above the melting point of the solder particles, a connecting portion connecting the first connection target member and the second connection target member is formed by the conductive material, and A method for manufacturing a connection structure, comprising a step of electrically connecting the first electrode and the second electrode by a solder portion in the connection portion. When the portion of the first electrode and the second electrode facing each other is seen in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the first electrode are seen. The method for manufacturing a connection structure according to claim 8, wherein a connection structure is obtained in which the solder portion in the connection portion is arranged in 50% or more of the area of 100% of the portions facing the electrodes of 2. ..

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