JP6767307B2 - Conductive material, connecting structure and manufacturing method of connecting 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, conductive particles are dispersed in the binder resin.

In order to obtain various connection structures, the anisotropic conductive material may be used, for example, for connecting a flexible printed circuit board and a glass substrate (FOG (Film on Glass)) or connecting a semiconductor chip and a flexible printed circuit board (COF (COF). It is used for Chip on Film)), connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and 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 conductive particles is arranged on the glass epoxy substrate. To do. Next, the flexible printed circuit boards are laminated and 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 conductive material containing a plurality of conductive particles having solder on the outer surface portion of the conductive portion, a thermosetting compound, and an acid anhydride thermosetting agent. The viscosity of the conductive material at 50 ° C. is 10 Pa · s or more and 200 Pa · s or less. Further, Patent Document 1 does not describe any SP value of the thermosetting compound and the acid anhydride thermosetting agent.

Patent Document 2 below discloses an adhesive composition for connecting a solar cell and a circuit board. The adhesive composition contains a thermosetting resin composition containing an acrylic compound and a thermosetting resin. The double bond equivalents of the acrylic compound are 90 or more and 500 or less. The content of the acrylic compound is 5% by mass or more and 50% by mass or less with respect to 100% by mass of the thermosetting resin composition. The acid value of the thermosetting resin composition is 5 mgKOH / g or more and 50 mgKOH / g or less. In Patent Document 2, the adhesive composition may contain a lead-free solder powder having a melting point of 240 ° C. or lower and a curing agent. Further, Patent Document 2 does not describe any SP value of the thermosetting resin and the curing agent.

WO2017 / 033935A1 Japanese Unexamined Patent Publication No. 2013-76045

In recent years, in order to support high-speed transmission of electronic devices, a connection structure having a small gap between members to be connected has been required. In order to reduce the gap between the members to be connected, it is necessary to make the solder bumps used for electrical connection between the electrodes thin, and it is necessary to reduce the particle size of the solder particles used for the solder bumps. In the conventional conductive material, if the particle size of the solder particles or the conductive particles is reduced, the storage stability (pot life) of the conductive material may be deteriorated. With conventional conductive materials, it is difficult to achieve both a reduction in the gap between the members to be connected and an increase in storage stability of the conductive material.

An object of the present invention is to provide a conductive material capable of effectively reducing the gap between members to be connected and effectively enhancing the storage stability of the conductive material. Another object of the present invention is to provide a connection structure using the above-mentioned conductive material and a method for manufacturing the connection structure.

According to a broad aspect of the present invention, it is a conductive material containing a first curable compound, a curing agent, and solder particles, and the conductive material does not contain or contains a second curable compound. The absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 2 or more, and the SP value of the second curable compound and the SP value of the curing agent The absolute value of the difference is less than 2, and the content of the first curable compound is 5% by weight or more in the total of 100% by weight of the first curable compound and the second curable compound. A conductive material is provided in which the d90 of the solder particles is 10 μm or less in the particle size distribution based on the volume of the solder particles.

In a specific aspect of the conductive material according to the present invention, the conductive material contains the second curable compound in a total of 100% by weight of the first curable compound and the second curable compound. The content of the first curable compound is 90% by weight or less.

In a specific aspect of the conductive material according to the present invention, the content of the second curable compound is 10% by weight in a total of 100% by weight of the first curable compound and the second curable compound. % Or more.

In a specific aspect of the conductive material according to the present invention, the absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 5.5 or less.

In certain aspects of the conductive material according to the present invention, the curing agent is an acid anhydride curing agent.

In certain aspects of the conductive material according to the present invention, the first curable compound is an aliphatic compound.

In certain aspects of the conductive material according to the present invention, the first curable compound is an aliphatic epoxy compound.

In certain aspects of the conductive material according to the present invention, the conductive material comprises an organophosphorus compound.

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. The connection portion is provided with a connection portion connecting the second connection target member, 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 connecting 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 and the said of the conductive material using the above-mentioned 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, there is provided a method for manufacturing a connection structure, 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 arranged 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 is a conductive material containing a first curable compound, a curing agent, and solder particles, and the conductive material does not contain or contains a second curable compound. The absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 2 or more, and the difference between the SP value of the second curable compound and the SP value of the curing agent. The absolute value of is less than 2, and the content of the first curable compound is 5% by weight or more in the total of 100% by weight of the first curable compound and the second curable compound. Since the d90 of the solder particles is 10 μm or less in the particle size distribution based on the volume of the solder particles, the gap between the members to be connected can be effectively reduced, and the conductive material can be stored and stabilized. The sex can be effectively enhanced.

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.

The details of the present invention will be described below.

(Conductive material)
The conductive material according to the present invention contains a first curable compound, a curing agent, and solder particles. The conductive material according to the present invention does not contain or contains a second curable compound. In the conductive material according to the present invention, the absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 2 or more. In the conductive material according to the present invention, the absolute value of the difference between the SP value of the second curable compound and the SP value of the curing agent is less than 2. In the conductive material according to the present invention, the content of the first curable compound is 5% by weight or more in the total of 100% by weight of the first curable compound and the second curable compound. In the conductive material according to the present invention, the d90 of the solder particles is 10 μm or less in the particle size distribution based on the volume of the solder particles.

In the present invention, since the above configuration is provided, the gap between the members to be connected can be effectively reduced, and the storage stability of the conductive material can be effectively enhanced.

In order to reduce the gap between the members to be connected in the connection structure, it is necessary to make the solder bumps used for electrical connection between the electrodes thin, and it is necessary to reduce the particle size of the solder particles used for the solder bumps. There is. The present inventors have found that when the particle size of the solder particles becomes smaller, the storage stability (pot life) of the conductive material deteriorates. As a result of diligent studies to suppress deterioration of the storage stability of the conductive material, the present inventors have adopted the above-mentioned configuration using a specific curable compound and a specific curing agent to obtain solder particles. It has been found that the storage stability of the conductive material can be effectively improved even if the particle size is reduced. In the present invention, since the above configuration is provided, both the reduction of the gap between the members to be connected and the improvement of the storage stability of the conductive material can be achieved at the same time.

Further, at the time of manufacturing the connection structure, after the conductive material is arranged on the connection target member such as a substrate by screen printing or the like, it may be left for a certain period of time until the conductive material is electrically connected. Since the storage stability (pot life) cannot be improved with the conventional conductive material, for example, when the conductive material is left for a certain period of time after being placed, the conductive material thickens and solder particles are formed on the electrode. It cannot be arranged efficiently, and the reliability of conduction between the electrodes may decrease. In the present invention, the above configuration is adopted, and the storage stability (pot life) of the conductive material can be effectively enhanced. Therefore, even if the conductive material is left for a certain period of time after being placed, the conductive material can be left. Thickening can be prevented, solder particles can be efficiently arranged on the electrodes, and the reliability of conduction between the electrodes can be sufficiently enhanced.

Further, in the present invention, since the above configuration is provided, when the electrodes are electrically connected, a plurality of solder particles are likely to collect between the upper and lower facing electrodes, and the plurality of solder particles are electrodeposed ( Can be placed efficiently on the line). Further, it is difficult for some of the plurality of 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 electrodes 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 the present invention, it is possible to prevent the displacement 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.

Even when the conductive material is left for a certain period of time, from the viewpoint of more efficiently arranging the solder on the electrode and further effectively improving the storage stability of the conductive material, the temperature of the conductive material is 25 ° C. The viscosity (η25) of the above is preferably 20 Pa · s or more, more preferably 30 Pa · s or more, preferably 400 Pa · s or less, and more preferably 300 Pa · s or less. The viscosity (η25) can be appropriately adjusted depending on the type and amount of the compounding components.

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 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 preferably 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 "methacryl".

(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 formed 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 refers to 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.

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 can 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 above 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 come into surface contact rather than point contact, so that the connection resistance is low. Further, as a result of increasing the joint strength between the solder portion and the electrode by using the solder particles, peeling between the solder portion and the electrode is more difficult to occur, and the continuity reliability and the connection reliability are further improved.

The low melting point metal constituting the solder particles is not particularly limited. The low melting point 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 it has 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 type (117 ° C. eutectic) or a tin-bismuth type (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 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, chromium, 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, antimonide, 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.

In the conductive material according to the present invention, the d90 of the solder particles is 10 μm or less in the particle size distribution based on the volume of the solder particles. From the viewpoint of further effectively reducing the gap between the members to be connected, the d90 of the solder particles is preferably 6 μm or less, more preferably 4 μm or less, in the particle size distribution based on the volume of the solder particles. The lower limit of d90 of the solder particles is not particularly limited. The d90 of the solder particles may be 0.5 μm or more. Further, in the particle size distribution based on the volume of the solder particles, when d90 of the solder particles is not more than the upper limit, the gap between the members to be connected becomes even smaller.

The d90 of the solder particles is the particle diameter of the solder particles when the cumulative volume of the solder particles is 90%. The d90 of the solder particles can be calculated from the particle size distribution on a volume basis.

The particle size distribution based on the volume of the solder particles can be obtained by using a laser diffraction type particle size distribution measuring device. Examples of the laser diffraction type particle size distribution measuring device include "Master Sizar 3000" manufactured by Malvern.

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. It is 30% 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, the solder particles can be arranged more efficiently on the electrodes, and it is easy to arrange a large amount of solder between the electrodes. Continuity reliability becomes even higher. From the viewpoint of further enhancing the conduction reliability, it is preferable that the content of the solder particles is large.

(1st curable compound and 2nd curable compound)
The first curable compound is not particularly limited. As the first curable compound, a known curable compound can be used. The first curable compound may be a photocurable compound or a thermosetting compound. The first curable compound may be an aliphatic compound from the viewpoint of further effectively reducing the gap between the members to be connected and further effectively enhancing the storage stability of the conductive material. preferable.

The conductive material does not contain or contains a second curable compound. The conductive material may or may not contain the second curable compound. From the viewpoint of further effectively enhancing the connection reliability of the connecting target member connected by the conductive material, the conductive material preferably contains the second curable compound.

The second curable compound is not particularly limited. As the second curable compound, a known insulating curable compound is used. The second curable compound may be a photocurable compound or a thermosetting compound.

From the viewpoint of further effectively enhancing the connection reliability of the members to be connected connected by the conductive material and further effectively enhancing the storage stability of the conductive material, the first curable compound is heat. It is preferably a curable compound.

From the viewpoint of further effectively enhancing the connection reliability of the members to be connected connected by the conductive material and further effectively enhancing the storage stability of the conductive material, the second curable compound is heat. It is preferably a curable compound.

The thermosetting compound is a compound that can be cured by heating. 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. From the viewpoint of further effectively enhancing the connection reliability of the members to be connected connected by the conductive material and further effectively enhancing the storage stability of the conductive material, the thermosetting compound may be an epoxy compound or an epoxy compound. It is preferably an episulfide compound, more preferably 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. , Fluorene type epoxy compound, phenol aralkyl type epoxy compound, naphthol aralkyl type epoxy compound, dicyclopentadiene type epoxy compound, anthracene type epoxy compound, adamantan skeleton epoxy compound, tricyclodecane skeleton epoxy compound, naphthylene ether type Examples thereof include epoxy compounds and epoxy compounds having a triazine nucleus as a skeleton. Only one type of the epoxy compound may be used, or two or more types 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 effectively enhancing the connection reliability of the members to be connected connected by the conductive material and further effectively enhancing the storage stability of the conductive material, the first curable compound is an epoxy. It is preferably a compound, more preferably an aliphatic epoxy compound.

From the viewpoint of further effectively enhancing the connection reliability of the members to be connected connected by the conductive material and further effectively enhancing the storage stability of the conductive material, the second curable compound is an epoxy. It is preferably a compound.

In the conductive material according to the present invention, the content of the first curable compound is 5% by weight or more in the total of 100% by weight of the first curable compound and the second curable compound. The content of the first curable compound is preferably 5% by weight or more, more preferably 15% by weight or more, based on 100% by weight of the total of the first curable compound and the second curable compound. Yes, preferably 90% by weight or less, more preferably 70% by weight or less. When the content of the first curable compound is not less than the above lower limit and not more than the above upper limit, the gap between the members to be connected can be reduced more effectively, and the storage stability of the conductive material is further improved. Can be effectively enhanced. Further, when the content of the first curable compound is not more than the above upper limit, the gel fraction of the cured product becomes high, and the gap retention property is further improved due to the cured product portion of the connecting structure. Become.

The content of the second curable compound is preferably 10% by weight or more, more preferably 30% by weight or more, based on 100% by weight of the total of the first curable compound and the second curable compound. Yes, preferably 95% by weight or less, more preferably 85% by weight or less. When the content of the second curable compound is not less than the above lower limit and not more than the above upper limit, the connection reliability of the connecting target member connected by the conductive material becomes more effective, and the storage stability of the conductive material becomes stable. The sex can be enhanced even more effectively.

The content of the first curable compound in 100% by weight of the conductive material is preferably 0.5% by weight or more, more preferably 2.25% by weight or more, and preferably 36% by weight or less, more preferably. Is 21% by weight or less. When the content of the first curable compound is not less than the above lower limit and not more than the above upper limit, the connection reliability of the connecting target member connected by the conductive material becomes more effective, and the storage stability of the conductive material becomes stable. The sex can be enhanced even more effectively.

The content of the second curable compound in 100% by weight of the conductive material is preferably 1% by weight or more, more preferably 4.5% by weight or more, preferably 38% by weight or less, more preferably 25% by weight. It is 5.5% by weight or less. When the content of the second curable compound is not less than the above lower limit and not more than the above upper limit, the connection reliability of the connecting target member connected by the conductive material becomes more effective, and the storage stability of the conductive material becomes stable. The sex can be enhanced even more effectively.

(Hardener)
The curing agent is not particularly limited. The curing agent cures the first curable compound and the second curable compound. The curing agent may be a thermosetting agent or a photopolymerization initiator. Only one kind of the above-mentioned curing agent may be used, or two or more kinds may be used in combination.

In the conductive material according to the present invention, the absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 2 or more. From the viewpoint of further effectively reducing the gap between the members to be connected and further effectively enhancing the storage stability of the conductive material, the SP value of the first curable compound and the SP of the curing agent The absolute value of the difference from the value is preferably 2.2 or more, more preferably 2.6 or more, preferably 5.5 or less, and more preferably 4.3 or less. Further, when the absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is at least the above lower limit, the storage stability of the conductive material can be effectively enhanced, and the conductivity can be improved. Even if the material is left for a certain period of time after being arranged, the thickening of the conductive material can be prevented, the solder particles can be efficiently arranged on the electrodes, and the conduction reliability between the electrodes can be sufficiently enhanced. ..

In the conductive material according to the present invention, the absolute value of the difference between the SP value of the second curable compound and the SP value of the curing agent is less than 2. From the viewpoint of further effectively reducing the gap between the members to be connected and further effectively enhancing the storage stability of the conductive material, the SP value of the second curable compound and the SP of the curing agent The absolute value of the difference from the value is preferably 1.9 or less, more preferably 1.5 or less. The lower limit of the absolute value of the difference between the SP of the second curable compound and the SP of the curing agent is not particularly limited. The absolute value of the difference between the SP of the second curable compound and the SP of the curing agent may be 0 or more.

The curing agent is preferably a thermosetting agent from the viewpoint of further effectively reducing the gap between the members to be connected and further effectively enhancing the storage stability of the conductive material.

The thermosetting agent heat-cures a thermosetting compound. Examples of the heat curing agent include an imidazole curing agent, a phenol curing agent, a thiol curing agent, an amine curing agent, an acid anhydride curing agent, a thermocation curing agent, a thermal radical generating agent, and the like. From the viewpoint of further effectively reducing the gap between the members to be connected and further effectively enhancing the storage stability of the conductive material, the thermosetting agent is preferably an acid anhydride curing agent. .. Only one type of the thermosetting agent may be used, or two or more types may be used in combination.

The imidazole curing agent is not particularly limited, and 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimerite, 2, 4-Diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s- Examples thereof include triazine isocyanuric acid adduct.

The thiol curing agent is not particularly limited, and examples thereof include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. ..

The amine curing agent is not particularly limited, and is hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5.5]. Examples thereof include undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine and diaminodiphenylsulfone.

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. The acid anhydride curing agent is, for example, phthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride. Acid, phthalic acid derivative anhydride, maleic anhydride, nadic acid anhydride, methylnagic anhydride, glutaric anhydride, succinic anhydride, glycerinbis trimellitic anhydride monoacetate, ethyleneglycolbis trimellitic anhydride, etc. 2 Trifunctional acid anhydride curing agents such as functional acid anhydride curing agents and trimellitic anhydride, as well as pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, methylcyclohexenetetracarboxylic acid anhydride, and polyazeline acid anhydride. Examples thereof include a tetrafunctional or higher functional acid anhydride curing agent.

From the viewpoint of further effectively reducing the gap between the members to be connected and further effectively enhancing the storage stability of the conductive material, the curing agent is preferably an acid anhydride curing agent.

From the viewpoint of more effectively suppressing the thermal deterioration of the cured product, the acid anhydride curing agent is preferably a cyclic acid anhydride curing agent. Examples of the cyclic acid anhydride curing agent include trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and triacrylic tetrahydrophthalic anhydride.

Examples of the thermal cation curing agent include an iodonium-based cation curing agent, an oxonium-based cation curing agent, and a sulfonium-based cation curing agent. Examples of the iodonium-based cationic curing agent include bis (4-tert-butylphenyl) iodonium 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, and examples thereof 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.

From the viewpoint of further effectively enhancing the connection reliability of the members to be connected connected by the conductive material and further effectively enhancing the storage stability of the conductive material, the curing agent is solid at 25 ° C. Is preferable.

From the viewpoint of more efficiently arranging the solder particles on the electrodes, the melting point of the curing agent is preferably lower than the melting point of the solder particles.

The content of the curing agent is not particularly limited. The content of the curing agent in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 10% by weight or more, preferably 50% by weight or less, and more preferably 40% by weight or less. When the content of the curing agent is at least the above lower limit, it is easy to sufficiently cure the first curable compound and the second curable compound. When the content of the curing agent is not more than the above upper limit, it becomes difficult for excess curing agent that was not involved in curing to remain after curing, and the heat resistance of the cured product becomes even higher.

The content of the curing agent is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, based on 100 parts by weight of the total of the first curable compound and the second curable compound. It is preferably 200 parts by weight or less, more preferably 150 parts by weight or less. When the content of the curing agent is at least the above lower limit, it is easy to sufficiently cure the first curable compound and the second curable compound. When the content of the curing agent is not more than the above upper limit, it becomes difficult for excess curing agent that was not involved in curing to remain after curing, and the heat resistance of the cured product becomes even higher.

(Organophosphorus compound)
The conductive material according to the present invention may contain an organic phosphorus compound. Only one kind of the above-mentioned organic phosphorus compound may be used, or two or more kinds may be used in combination.

From the viewpoint of more efficiently arranging the solder particles on the electrode, the above-mentioned organic phosphorus compound is an organic phosphonium salt, an organic phosphoric acid, an organic phosphoric acid ester, an organic phosphonic acid, an organic phosphonic acid ester, an organic phosphinic acid, or It is preferably an organic phosphinic acid ester. From the viewpoint of more efficiently arranging the solder particles on the electrode, the organic phosphorus compound is more preferably an organic phosphonium salt.

Examples of the organic phosphonium salt include an organic phosphonium salt composed of a phosphonium ion and a counterion thereof. Examples of commercially available products of the organic phosphonium salt include the "Hishikorin" series manufactured by Nippon Chemical Industrial Co., Ltd. Only one kind of the organic phosphonium salt may be used, or two or more kinds may be used in combination.

The organic phosphoric acid, the organic phosphoric acid ester, the organic phosphonic acid, the organic phosphonic acid ester, the organic phosphinic acid, and the organic phosphinic acid ester are not particularly limited, and conventionally known compounds and commercially available products are used. Can be done. Only one of these may be used, or two or more thereof may be used in combination.

From the viewpoint of more efficiently arranging the solder particles on the electrode, the melting point of the organic phosphorus compound is preferably 170 ° C. or lower. From the viewpoint of more efficiently arranging the solder particles on the electrode, the organic phosphorus compound is preferably liquid at 25 ° C.

From the viewpoint of more efficiently arranging the solder particles on the electrode, the melting point of the organic phosphorus compound is preferably lower than the melting point of the curing agent.

The content of the organic phosphorus 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, more preferably more preferably, with respect to 100 parts by weight of the curing agent. It is 8 parts by weight or less. When the content of the organic phosphorus compound 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.

(flux)
The conductive material preferably contains a flux. By using the flux, the solder particles can be arranged more efficiently on the electrode. The above flux is not particularly limited. As the flux, a flux generally used for solder bonding or the like can be used.

Examples of the flux include 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, and an organic substance. Examples include acid and pine fat. Only one type of the above flux may be used, or two or more types may be used in combination.

Examples of the molten salt include ammonium chloride and the like. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid and glutaric acid. Examples of the above-mentioned pine resin include activated pine resin and non-activated pine resin. The flux is preferably an organic acid or pine resin having two or more carboxyl groups. The flux may be an organic acid having two or more carboxyl groups, or may be pine resin. By using an organic acid or pine resin having two or more carboxyl groups, the conduction reliability between the electrodes is further improved.

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 carboxybenzotriazole and the like.

The above pine resin 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 melting point (active temperature) of the flux is preferably 10 ° C. or higher, more 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 higher. Below, it is even more preferably 160 ° C. or lower, further preferably 150 ° C. or lower, and even more preferably 140 ° C. or lower. When the melting point of the flux is at least the above lower limit and at least the above upper limit, the flux effect is exhibited more effectively, and the solder particles are arranged more efficiently on the electrodes. The melting point (active temperature) of the flux is preferably 80 ° C. or higher and 190 ° C. or lower. The melting point (active temperature) 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.

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

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

Examples of the flux that releases cations by the above heating include the above-mentioned thermal cation curing agent.

The flux is more preferably a salt of an acid compound and a base compound. The acid compound preferably has an effect of cleaning the surface of a metal, and the base compound preferably has an effect of neutralizing the acid compound. The flux is preferably a neutralization reaction product of the acid compound and the base compound. Only one type of the above flux may be used, or two or more types may be used in combination.

From the viewpoint of more efficiently arranging the solder particles on the electrodes, the melting point of the flux is preferably lower than the melting point of the solder particles, more preferably 5 ° C. or higher, and 10 ° C. or higher. Is even more preferable. However, the melting point of the flux may be higher than the melting point of the solder particles. Normally, the working temperature of the conductive material is equal to or higher than the melting point of the solder particles, and if the melting point of the flux is lower than the working temperature of the conductive material, even if the melting point of the flux is higher than the melting point of the solder particles, the above The flux can sufficiently exhibit the performance as a flux. For example, in a conductive material in which the operating temperature of the conductive material is 150 ° C. or higher and contains solder particles (Sn42Bi58: melting point 139 ° C.) and a flux (melting point 146 ° C.) which is a salt of malic acid and benzylamine, the apple Flux, which is a salt of acid and benzylamine, exhibits a sufficient flux action.

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

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, isophthalic acid which is an aromatic carboxylic acid, terephthalic acid, trimellitic acid, ethylenediamine tetraacetic acid and the like. The acid compound is preferably glutaric acid, azelaic acid, or malic 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. .. The basic compound is preferably benzylamine, 2-methylbenzylamine, or 3-methylbenzylamine.

The flux may be dispersed in the conductive material or may be adhered to the surface of the solder particles. From the viewpoint of further enhancing the flux effect, it is preferable that the flux adheres to the surface of the solder particles.

From the viewpoint of further effectively enhancing the storage stability of the conductive material, the flux is preferably solid at 25 ° C., and the flux is dispersed as a solid in the conductive material at 25 ° C. 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. 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 agglomerated 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. Is. When the content of the filler is not less than the above lower limit and not more than the above upper limit, the solder particles are arranged more efficiently on the electrode.

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

(Connecting structure and manufacturing method of connecting 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 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 using the above-mentioned conductive material, and the above-mentioned conductivity. On the surface of the material opposite to the side of the first connection target member, the second connection target member having the second electrode on the surface is provided so that the first electrode and the second electrode face each other. By heating the conductive material to a temperature equal to or higher than the melting point of the solder particles, the connecting portion connecting the first connection target member and the second connection target member is formed with the conductive material. The first electrode and the second electrode are electrically connected by a solder portion in the connecting 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 placed efficiently on the line). Further, it is difficult for some of the solder particles to be arranged in the region (space) where the electrodes are not formed, and the amount of the solder particles arranged in the region where the electrodes are 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 100% of 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, and in the step of arranging the second connection target member and the step of forming the connection portion, the conductive material exceeds the force of the weight of the second connection target member. It is preferable that no pressurizing pressure is applied. In these cases, the uniformity of the amount of solder can be further improved in the plurality of solder portions. Further, 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). it 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. it can. Therefore, the conduction 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. It includes a part 4. The connecting portion 4 is formed of the above-mentioned conductive material. In the present embodiment, the conductive material includes a first curable compound, a second curable compound, a curing agent, and solder particles. 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 thermoset.

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, no solder particles are 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. In a 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, a melt of the solder particles is formed. Soldered and spread on the surface of the electrode 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 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 flux, the flux is generally gradually deactivated 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 opposite 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 the present 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.

From the viewpoint of further enhancing the conduction reliability, in the connection structures 1 and 1X, the first electrodes 2a and the second electrodes 2a and the second electrodes 2a and the second electrodes 2a in the stacking direction of the first electrode 2a, the connection portions 4, 4X and the second electrode 3a. When looking at the parts facing each other with the electrodes 3a, 50% or more of the area of the parts facing each other between the first electrode 2a and the second electrode 3a is 50% or more, and the solder parts in the connecting parts 4 and 4X. It is preferable that 4A and 4XA are arranged.

From the viewpoint of further enhancing the conduction reliability, the portion where the first electrode and the second electrode face each other is seen in the stacking direction of the first electrode, the connection portion, and the second electrode. Occasionally, 50% or more (more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more) of the area of the portion where the first electrode and the second electrode face each other is 100% or more. , Most preferably 90% or more), the solder portion in the connection portion is preferably arranged.

From the viewpoint of further enhancing the conduction reliability, the first electrode and the second electrode face each other in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the matching portions, 60% or more (more preferably 70% or more, still more preferably 90%) of the solder portion in the connecting portion is in the portion where the first electrode and the second electrode face each other. Above, it is particularly preferable that 95% or more, most preferably 99% or more) is arranged.

Next, an example of a method for manufacturing the connection structure 1 using the conductive material according to the embodiment of the present invention will be described.

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 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 front 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-aggregation 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 joined 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 connecting target member 2 and the second connecting 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 thermosetting 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 moving, and then the first 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 are more effectively gathered between the first electrode 2a and the second electrode 3a. When pressurization is performed 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 pressure is not applied, when the second connection target member is superposed on the first connection target member coated with the conductive material, the electrode of the first connection target member is used. Even in a state where the second connection target member is out of alignment with the electrodes, the misalignment can be corrected and the electrodes can be connected to each other (self-alignment effect). This is because the molten solder that is self-aggregated between the electrodes of the first connection target member and the electrodes of the second connection target member is the electrode of the first connection target member and the second connection target member. Since the area where the solder between the electrodes and other components of the conductive material come into contact with each other is the smallest, the energy is more stable. Therefore, the force to make the connection structure with alignment, which is the connection structure with the minimum area. Is to work. 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, further 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.

The viscosity of the conductive material at the melting point of the solder particles is determined by using STRESSTECH (manufactured by EOLOGICA) or the like, strain control 1 rad, frequency 1 Hz, heating rate 20 ° C./min, measurement temperature range 25 to 200 ° C. 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 to move 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 or a connection structure above the melting point of the solder particles and above the curing temperature of the thermosetting compound. 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 substrates, glass epoxy substrates, and circuit boards such as glass substrates. 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 circuit board, 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 circuit board, a flexible flat cable, or a rigid flexible substrate. Resin films, flexible printed circuit boards, flexible flat cables, and rigid flexible substrates have the properties of high flexibility and relatively light weight. When a conductive film is used to connect 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 circuit board, 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, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate is used, the continuity reliability between the electrodes is improved by not applying pressure, as compared with the case where other members to be connected such as a semiconductor chip 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 electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, silver electrodes or copper electrodes. When the connection target member is a glass substrate, the electrodes are preferably aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes or tungsten electrodes. 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 in 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 exhibited even more effectively. 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 connection target member 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 is sufficient. Since it is necessary for the solder particles to agglomerate uniformly in the above method, the amount of solder tends to be non-uniform in the conventional method, whereas the effect of the present invention is more effectively exhibited in the method of the present invention. To.

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.

Curable compound:
(1) Curable compound 1: Aliphatic epoxy compound, "Epolite 1600" manufactured by Kyoeisha Chemical Co., Ltd., SP value: 9.8
(2) Curable compound 2: Aliphatic epoxy compound, "Epolite 100E" manufactured by Kyoeisha Chemical Co., Ltd., SP value: 10.2
(3) Curable compound 3: Aliphatic epoxy compound, "Epolite 40E" manufactured by Kyoeisha Chemical Co., Ltd., SP value: 10.4
(4) Curable compound 4: Bisphenol A type epoxy compound, "YD-8125" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., SP value: 10.5
(5) Curable compound 5: Bisphenol F type epoxy compound, "YDF-8170C" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., SP value: 11
(6) Curable compound 6: Isocyanul skeleton-containing epoxy compound, "TEPIC-VL" manufactured by Nissan Chemical Industries, Ltd., SP value: 12.9
(7) Curable compound 7: Alicyclic epoxy compound, "Celoxide 2021P" manufactured by Daicel, SP value: 12

Hardener:
(1) Hardener 1: Acid anhydride hardener, "Recasid TH" manufactured by New Japan Chemical Co., Ltd., SP value: 12.4
(2) Hardener 2: Acid anhydride hardener, "Recasid SA" manufactured by New Japan Chemical Co., Ltd., SP value: 12.5
(3) Hardener 3: Acid anhydride Hardener, "Pyromellitic anhydride" manufactured by Tokyo Chemical Industry Co., Ltd., SP value: 13.8
(4) Hardener 4: Acid anhydride hardener, "Recasid TMTA-C" manufactured by New Japan Chemical Co., Ltd., SP value: 14
(5) Hardener 5: Acid anhydride hardener, "Recasid TMEG" manufactured by New Japan Chemical Co., Ltd., SP value: 14.7

Organophosphorus compounds:
(1) Organophosphorus compound 1: Organic phosphonium salt, "PX-4B" manufactured by Nippon Chemical Industrial Co., Ltd.
(2) Organophosphorus compound 2: Organic phosphonium salt, "PX-4MP" manufactured by Nippon Chemical Industrial Co., Ltd.
(3) Organophosphorus compound 3: Organic phosphonium salt, "PX-4ET" manufactured by Nippon Chemical Industrial Co., Ltd.
(4) Organophosphorus compound 4: Organic phosphonium salt, "PX-4BT" manufactured by Nippon Chemical Industrial Co., Ltd.

Solder particles:
Solder particles 1: SnBi solder particles, "Sn42Bi58" manufactured by Mitsui Mining & Smelting Co., Ltd., d90: 4 μm
Solder particles 2: SnBi solder particles, "Sn42Bi58" manufactured by Mitsui Mining & Smelting Co., Ltd., d90: 6 μm
Solder particles 3: SnBi solder particles, "Sn42Bi58" manufactured by Mitsui Mining & Smelting Co., Ltd., d90: 10 μm
Solder particles 4: SnBi solder particles, "Sn42Bi58" manufactured by Mitsui Mining & Smelting Co., Ltd., d90: 15 μm

SP values of curable compounds and hardeners:
The SP values of the curable compound and the curing agent were calculated by the Fedors estimation method.

Solder particle d90:
The particle size distribution of the solder particles based on the volume was measured with a laser diffraction type particle size distribution measuring device (“Mastersizer 3000” manufactured by Malvern). From the results of the obtained particle size distribution, d90 of the solder particles (particle size of the solder particles when the cumulative volume of the solder particles is 90%) was determined.

(Examples 1 to 19 and Comparative Examples 1 to 3)
(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). It was.

(2-1) Specific method for producing the connection structure under condition A:
As the first connection target member, copper electrodes of 250 μm at a pitch of 400 μm are arranged in an area array on the surface of the semiconductor chip body (size 5 × 5 mm, thickness 0.4 mm), and a passivation film (passivation film) is arranged on the outermost surface. A semiconductor chip having a polyimide, a thickness of 5 μm, and an electrode opening diameter of 200 μm) was prepared. The number of copper electrodes is 10 x 10 per semiconductor chip, for a total of 100.

As the second connection target member, the same pattern is formed on the surface of the glass epoxy substrate main body (size 20 × 20 mm, thickness 1.2 mm, material FR-4) with respect to the electrodes of the first connection target member. , A glass epoxy substrate was prepared in which a copper electrode was arranged and a solder resist film was formed in a region where the copper electrode was not arranged. The step between the surface of the copper electrode and the surface of the solder resist film is 15 μm, and the solder resist film protrudes from the copper electrode.

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 (anisometric conductive paste) layer. From that state, the temperature of the conductive material (anisotropic conductive paste) layer was heated to 139 ° C. (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 (anisometric 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.

(2-2) Specific method for producing the connection structure under condition B:
A connection structure (area array substrate) was produced in the same manner as in Condition A except that the following changes were made.

Changes from condition A to condition B:
A conductive material (anisotropic conductive paste) immediately after production is coated on 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, and then at 25 ° C. It was left in an environment of 50% humidity for 6 hours. After being left to stand, semiconductor chips were laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes face each other.

(Evaluation)
(1) Presence or absence of blending of the first curable compound and the second curable compound In the obtained conductive material, the first curable compound and the second curing are based on the SP values of the curable compound and the curing agent. It was confirmed whether or not the sex compound was contained. Whether or not the first curable compound and the second curable compound were blended was determined according to the following criteria.

[Criteria for determining whether or not the first curable compound is blended]
A: The conductive material contains the first curable compound B: The conductive material does not contain the first curable compound

[Criteria for determining the presence or absence of the second curable compound]
A1: The conductive material contains the second curable compound A2: The conductive material does not contain the second curable compound

(2) Gap In the connection structures obtained under the conditions A and B, the height (gap) of the solder portion in the connection portion was measured by a scanning electron microscope. The gap was determined according to the following criteria.

[Gap criteria]
○ ○: Gap is less than 5 μm ○: Gap is 5 μm or more and less than 10 μm Δ: Gap is 10 μm or more and less than 15 μm ×: Gap is 15 μm or more

(3) Placement accuracy of solder on electrodes In the connection structure obtained under conditions A and B, the first electrode and the second electrode are in the stacking direction of the first electrode, the connecting portion, and the second electrode. When looking at the parts facing each other with the electrodes, the ratio X of the area where the solder part in the connecting part is arranged in 100% of the area of the parts facing each other between the first electrode and the second electrode is defined as X. evaluated. The placement accuracy of the solder on the electrodes was judged according to the following criteria.

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

(4) Conductivity reliability between the upper and lower electrodes In the connection structures (n = 15) obtained under the conditions A and B, the connection resistance per connection point between the upper and lower electrodes is controlled by the 4-terminal method. Measured by. The average value of the connection resistance was calculated. From the relationship of voltage = current x 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 conduction 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 Δ: 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

(5) Insulation reliability between adjacent electrodes In the connection structures (n = 15) obtained under conditions A and B, the adjacent electrodes are left in an atmosphere of 85 ° C. and 85% humidity for 100 hours. In the meantime, 5 V was applied and the resistance value was measured at 25 points. The insulation reliability was judged according to the following criteria.

[Criteria for insulation reliability]
○○: connecting the average value of the resistance 10 ⁷ Omega more ○: connecting the average value of the resistor 10 ⁶ Omega to less than 10 ⁷ Ω △: connection mean value of the resistance 10 ⁵ Omega to less than 10 ⁶ Ω ×: Connection mean value of the resistance is less than 10 ⁵ Omega

(6) Gel fraction Among the components shown in Tables 1 and 2 below, components other than conductive particles were blended to obtain a curable composition. The obtained curable composition was heated at 160 ° C. for 1 hour 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 cured product after drying was measured. The gel fraction was calculated by the following formula. The gel fraction was determined according to the following criteria. The higher the gel fraction, the higher the gap retention due to the cured product portion of the connecting structure.

Gel fraction (%) = [Weight of cured product after toluene immersion (g) / Weight of cured product before toluene immersion (g)] x 100

[Criteria for gel fraction]
○○: Gel fraction is 90% or more and 100% or less ○: Gel fraction is 80% or more and less than 90% Δ: Gel fraction is 70% or more and less than 80% ×: 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 circuit board, 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 (13)

A conductive material containing a first curable compound, a curing agent, and solder particles.
The conductive material does not contain or contains a second curable compound.
The absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 2 or more.
The absolute value of the difference between the SP value of the second curable compound and the SP value of the curing agent is less than 2.
The content of the first curable compound is 5% by weight or more in a total of 100% by weight of the first curable compound and the second curable compound.
A conductive material in which d90 of the solder particles is 10 μm or less in the particle size distribution based on the volume of the solder particles. Contains the second curable compound
The conductive material according to claim 1, wherein the content of the first curable compound is 90% by weight or less in a total of 100% by weight of the first curable compound and the second curable compound. .. The first or second claim, wherein the content of the second curable compound is 10% by weight or more in a total of 100% by weight of the first curable compound and the second curable compound. Conductive material. The conductive material according to any one of claims 1 to 3, wherein the absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 5.5 or less. The conductive material according to any one of claims 1 to 4, wherein the curing agent is an acid anhydride curing agent. The conductive material according to any one of claims 1 to 5, wherein the first curable compound is an aliphatic compound. The conductive material according to any one of claims 1 to 6, wherein the first curable compound is an aliphatic epoxy compound. The conductive material according to any one of claims 1 to 7, which comprises an organic phosphorus compound. The conductive material according to any one of claims 1 to 8, 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,
A connecting portion connecting the first connection target member and the second connection target member is provided.
The material of the connecting portion is the conductive material according to any one of claims 1 to 9.
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 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 viewed. The connection structure according to claim 10, 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 9.
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 viewed. The method for manufacturing a connection structure according to claim 12, 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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