JP2016127010A - Anisotropic conductive material, connection structure and method for producing connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive material that allows solder particles to be disposed on electrodes efficiently and can improve conduction reliability between the electrodes.SOLUTION: An anisotropic conductive material according to the present invention is used for anisotropic conductive connection, and comprises a thermosetting component, a plurality of solder particles having solder on a conductive external surface, and flux. The solder particle is a surface-treated matter with dicarboxylic acid. A difference between second acid dissociation constant pKa2 of the dicarboxylic acid and first acid dissociation constant pKa1 of the flux: pKa2-pKa1 is 0.5 or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an anisotropic conductive material containing solder particles. The present invention also relates to a connection structure using the anisotropic 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 a binder resin.

  In order to obtain various connection structures, the anisotropic conductive material is, for example, a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)) or a connection between a semiconductor chip and a flexible printed circuit board (COF ( Chip on Film)), connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)), and the like.

  For example, when electrically connecting the electrode of the flexible printed circuit board and the electrode of the glass epoxy substrate by the anisotropic conductive material, an anisotropic conductive material containing conductive particles is disposed on the glass epoxy substrate. To do. Next, a flexible printed circuit board is laminated, and heated and pressurized. As a result, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

  As an example of the anisotropic conductive material, the following Patent Document 1 includes a resin layer containing a thermosetting resin, solder powder, and a curing agent, and the solder powder and the curing agent include the resin layer. An adhesive tape present therein is disclosed. This adhesive tape is in the form of a film, not a paste.

  Patent Document 1 discloses a bonding method using the above-mentioned adhesive tape. Specifically, a first substrate, an adhesive tape, a second substrate, an adhesive tape, and a third substrate are laminated in this order from the bottom to obtain a laminate. At this time, the first electrode provided on the surface of the first substrate is opposed to the second electrode provided on the surface of the second substrate. Moreover, the 2nd electrode provided in the surface of the 2nd board | substrate and the 3rd electrode provided in the surface of the 3rd board | substrate are made to oppose. Then, the laminate is heated and bonded at a predetermined temperature. Thereby, a connection structure is obtained.

WO2008 / 023452A1

  The adhesive tape described in Patent Document 1 is in a film form and not in a paste form. For this reason, it is difficult to efficiently arrange the solder powder on the electrodes (lines). For example, in the adhesive tape described in Patent Document 1, a part of the solder powder is easily placed in a region (space) where no electrode is formed. Solder powder disposed in a region where no electrode is formed does not contribute to conduction between the electrodes.

  Moreover, even if it is the anisotropic conductive paste containing solder powder, solder powder may not be efficiently arrange | positioned on an electrode (line).

  Moreover, even if it is an electroconductive film, the electroconductive material in which solder powder can arrange | position efficiently on an electrode (line) is desired.

  An object of the present invention is to provide an anisotropic conductive material that can efficiently arrange solder particles on electrodes and can improve conduction reliability between the electrodes. Moreover, this invention is providing the manufacturing method of the connection structure using the said anisotropic conductive material, and a connection structure.

  According to a wide aspect of the present invention, there is provided an anisotropic conductive material used for anisotropic conductive connection, including a thermosetting component, a plurality of solder particles having solder on a conductive outer surface, and a flux. The solder particles are a surface treatment product of dicarboxylic acid, and the difference between the second acid dissociation constant pKa2 of the dicarboxylic acid and the first acid dissociation constant pKa1 of the flux: pKa2−pKa1 is 0.5 or more. An anisotropic conductive material is provided.

  The content of the solder particles is preferably 10% by weight or more and 90% by weight or less, and more preferably 10% by weight or more and 60% by weight or less.

  On the specific situation with the anisotropic electrically-conductive material which concerns on this invention, the said solder particle is a surface treatment thing by the compound used as an anion polymer or an anion polymer.

  In a specific aspect of the anisotropic conductive material according to the present invention, the anisotropic conductive material has a property that the flux collects on the outer surface of the solder particles when heated to 110 ° C.

  On the specific situation with the anisotropic electrically-conductive material which concerns on this invention, the average particle diameter of the said solder particle is 1 micrometer or more and 60 micrometers or less.

  In a specific aspect of the anisotropic conductive material according to the present invention, the anisotropic conductive material is an anisotropic conductive paste.

  According to a wide aspect of the present invention, a first connection target member having at least one first electrode on the surface, a second connection target member having at least one second electrode on the surface, and the first The connection target member and a connection part connecting the second connection target member, wherein the material of the connection part is the anisotropic conductive material described above, and the first electrode and the first There is provided a connection structure in which two electrodes are electrically connected by a solder portion in the connection portion.

  According to a wide aspect of the present invention, the anisotropic conductive material is disposed on the surface of the first connection target member having at least one first electrode on the surface, using the anisotropic conductive material described above. And a second connection target member having at least one second electrode on the surface opposite to the first connection target member side of the anisotropic conductive material, Arranging the electrode and the second electrode to face each other, and heating the anisotropic conductive material to a temperature equal to or higher than a melting point of the solder particles and a temperature equal to or higher than a curing temperature of the thermosetting component. A connection portion connecting the connection target member and the second connection target member is formed of the anisotropic conductive material, and the first electrode and the second electrode are connected to each other. And a step of electrically connecting with a solder part in the part Manufacturing method is provided.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection portion, the anisotropic conductive material is not subjected to pressure. The weight of the second connection target member is added, or at least one of the step of arranging the second connection target member and the step of forming the connection portion is pressurized, and In both of the step of arranging the second connection target member and the step of forming the connection portion, the pressure of pressurization is less than 1 MPa.

  It is preferable that the second connection target member is a semiconductor chip, a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board.

  The anisotropic conductive material according to the present invention includes a thermosetting component, a plurality of solder particles having solder on a conductive outer surface, and a flux, and the solder particles are a surface-treated product of dicarboxylic acid, The difference between the second acid dissociation constant pKa2 of the dicarboxylic acid and the first acid dissociation constant pKa1 of the flux: pKa2−pKa1 is 0.5 or more. Therefore, when the electrodes are electrically connected, the solder particles Can be efficiently arranged on the electrodes, and the conduction reliability between the electrodes can be improved.

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

  Details of the present invention will be described below.

(Anisotropic conductive material)
The anisotropic conductive material according to the present invention is used for anisotropic conductive connection. In this specification, an anisotropic conductive material may be abbreviated as a conductive material. The conductive material according to the present invention includes a thermosetting component, a plurality of solder particles having solder on a conductive outer surface, and a flux.

  In the conductive material according to the present invention, the solder particles are a surface-treated product of dicarboxylic acid, and the difference between the second acid dissociation constant pKa2 of the dicarboxylic acid and the first acid dissociation constant pKa1 of the flux is pKa2−pKa1 It is 0.5 or more. That is, in the conductive material according to the present invention, the solder particles are surface-treated with dicarboxylic acid, the second acid dissociation constant pKa2 of the dicarboxylic acid used for the surface treatment of the solder particles, and the first acid of the flux. Difference from dissociation constant pKa1: pKa2−pKa1 is 0.5 or more.

  In the conductive material according to the present invention, the above-described configuration is adopted. Therefore, when the electrodes are electrically connected by heating the conductive material, a plurality of solder particles are easily collected between the upper and lower electrodes facing each other. A plurality of solder particles can be efficiently arranged on the electrode (line). Moreover, it is difficult for some of the plurality of solder particles to be disposed in a region (space) where no electrode is formed, and the amount of solder particles disposed in a region where no electrode is formed can be considerably reduced. Therefore, the conduction reliability between the electrodes can be improved. In addition, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, and to improve insulation reliability. The following reason can be considered that such an effect is obtained.

  When the dicarboxylic acid is bonded to the surface via one carboxyl group of the dicarboxylic acid used for the surface treatment of the solder particles, the acidity of the other carboxyl group is the second acid dissociation constant pKa2 of the dicarboxylic acid. Can be represented. The acidity of the flux can be expressed by the first acid dissociation constant pKa1. When the flux is activated by heat, the acid is preferentially generated from the flux in order to satisfy the relationship of the acid dissociation constant. For this reason, the generated acid moves to the surface of the solder particles, and the conventional negative charge on the surface of the solder particles can be canceled. For this reason, it is considered that the repulsion between the particles due to the surface charge of the solder particles can be suppressed, and the solder particles easily aggregate. As a result, even when the distance between adjacent electrodes is large, solder particles hardly remain between the electrodes, and the insulation reliability under high temperature and high humidity is increased.

  From the viewpoint of further efficiently arranging the solder particles on the electrode and further improving the conduction reliability and the insulation reliability, from the viewpoint of further suppressing the positional deviation between the electrodes, pKa2−pKa1 is preferably 0.65 or more, more preferably 0.8 or more.

  The acid dissociation constant pKa is measured as follows.

  It can be measured by a titration method using a pH meter or an automatic potentiometric titrator. As a titration method using a pH meter, an acid is dissolved in water, neutralization titration with a base such as sodium hydroxide is performed, and a titration curve is obtained. From this titration curve, the first and second acid dissociation constants can be determined.

  Furthermore, in the present invention, it is possible to prevent positional deviation between the electrodes. In the present invention, when the second connection target member is superimposed on the first connection target member to which the conductive material is applied, the alignment of the electrode of the first connection target member and the electrode of the second connection target member is performed. Even when the first connection target member and the second connection target member are overlapped in a shifted state, the shift is corrected and the electrodes of the first connection target member and the second connection target member are corrected. Can be connected (self-alignment effect). In order to obtain such an effect, the use of a conductive material having a specific composition that satisfies the relationship of the acid dissociation constant contributes greatly.

  In addition, when using conductive particles including base particles not formed of solder and a solder layer disposed on the surface of the base particles, the conductive particles are not formed on the electrodes. It becomes difficult to gather, and since the solder bonding property between the conductive particles is low, the conductive particles that have moved onto the electrode easily move out of the electrode. For this reason, the effect of suppressing the displacement between the electrodes is also reduced.

  The conductive material can be used as a conductive paste and a conductive film. The conductive material may be an anisotropic conductive film. From the viewpoint of more efficiently arranging the solder on the electrode, the conductive material is preferably an anisotropic conductive paste.

  In order to more efficiently arrange the solder particles on the electrode, the viscosity (η25) at 25 ° C. of the conductive paste is preferably 10 Pa · s or more, more preferably 50 Pa · s or more, and further preferably 100 Pa · s or more. , Preferably 800 Pa · s or less, more preferably 600 Pa · s or less, and even more preferably 500 Pa · s or less.

  The said viscosity ((eta) 25) can be suitably adjusted with the kind and compounding quantity of a compounding component. Further, the use of a filler can make the viscosity relatively high.

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

  The conductive material according to the present invention can be suitably used in a connection structure according to the present invention described later and a method for manufacturing the connection structure.

  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.

(Solder particles)
The solder particles have solder on a conductive outer surface. As for the said solder particle, both a center part and an electroconductive outer surface are formed with the solder. The solder particles are particles in which both the central portion and the outer surface of the conductive (conductive portion) are solder.

  From the viewpoint of efficiently collecting the solder particles on the electrode, the zeta potential on the surface of the solder particles is preferably positive. However, in the present invention, the zeta potential of the surface of the solder particle may not be positive.

  The zeta potential is measured as follows.

Zeta potential measurement method:
0.05 g of solder particles are put in 10 g of methanol and subjected to ultrasonic treatment or the like to uniformly disperse to obtain a dispersion. Using this dispersion and using “Delsamax PRO” manufactured by Beckman Coulter, the zeta potential can be measured at 23 ° C. by electrophoretic measurement.

  The zeta potential of the solder particles is preferably 0 mV or more, more preferably more than 0 mV, preferably 10 mV or less, more preferably 5 mV or less, even more preferably 1 mV or less, still more preferably 0.7 mV or less, particularly preferably 0.5 mV. It is as follows. If the zeta potential is less than or equal to the above upper limit, the solder particles hardly aggregate in the conductive paste before use. When the zeta potential is 0 mV or more, the solder particles efficiently aggregate on the electrode during mounting.

  Since it is easy to make the zeta potential of the surface positive, it is preferable that the solder particles have a solder particle main body and an anionic polymer disposed on the surface of the solder particle main body. The solder particles are preferably obtained by surface-treating the solder particle body with an anionic polymer or a compound that becomes an anionic polymer. The solder particles are preferably a surface treated product of an anion polymer or a compound that becomes an anion polymer. As for the said anion polymer and the compound used as the said anion polymer, only 1 type may respectively be used and 2 or more types may be used together.

  As a method of surface-treating the solder particle body with an anionic polymer, as an anionic polymer, for example, a (meth) acrylic polymer copolymerized with (meth) acrylic acid, synthesized from a dicarboxylic acid and a diol and having carboxyl groups at both ends Polyester polymer, polymer obtained by intermolecular dehydration condensation reaction of dicarboxylic acid and having carboxyl groups at both ends, polyester polymer synthesized from dicarboxylic acid and diamine and having carboxyl groups at both ends, and modified poval having carboxyl groups ( A method of reacting a carboxyl group of an anionic polymer with a hydroxyl group on the surface of a solder particle body using “GOHSEX T” manufactured by Nippon Synthetic Chemical Co., Ltd., etc.

Examples of the anion portion of the anion polymer include the carboxyl group, and other than that, a tosyl group (p-H ₃ CC ₆ H ₄ S (═O) ₂ ⁻ ), a sulfonate ion group (—SO ₃ ^— ), And phosphate ion groups (—PO ₄ ⁻ ) and the like.

  As another method, a compound having a functional group that reacts with a hydroxyl group on the surface of the solder particle body and having a functional group that can be polymerized by addition or condensation reaction is used. The method of polymerizing on the surface is mentioned. Examples of the functional group that reacts with the hydroxyl group on the surface of the solder particle body include a carboxyl group and an isocyanate group. Examples of the functional group that polymerizes by addition and condensation reactions include a hydroxyl group, a carboxyl group, an amino group, and (meth). An acryloyl group is mentioned.

  The weight average molecular weight of the anionic polymer is preferably 2000 or more, more preferably 3000 or more, preferably 10,000 or less, more preferably 8000 or less.

  When the weight average molecular weight is not less than the above lower limit and not more than the above upper limit, it is easy to dispose an anionic polymer on the surface of the solder particle body, and it is easy to make the zeta potential on the surface of the solder particle positive. The solder particles can be arranged on the electrodes even more efficiently.

  The weight average molecular weight indicates a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

  The weight average molecular weight of the polymer obtained by surface-treating the solder particle body with a compound that becomes an anionic polymer is obtained by dissolving the solder in the solder particles and removing the solder particles with dilute hydrochloric acid or the like that does not cause decomposition of the polymer. It can be determined by measuring the weight average molecular weight of the remaining polymer.

  The solder is preferably a metal (low melting point metal) having a melting point of 450 ° C. or lower. The solder particles are preferably metal particles (low melting point metal particles) having a melting point of 450 ° C. or lower. The low melting point metal particles are particles containing a low melting point metal. The low melting point metal is 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 include tin. In 100% by weight of the metal contained in the solder particles, the content of tin 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 content of tin in the solder particles is equal to or higher than the lower limit, the connection reliability between the solder portion and the electrode is further enhanced.

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

  By using the solder particles, the solder is melted and joined to the electrodes, and the solder portion conducts between the electrodes. For example, since the solder portion and the electrode are not in point contact but in surface contact, the connection resistance is lowered. In addition, the use of solder particles increases the bonding strength between the solder portion and the electrode. As a result, peeling between the solder portion and the electrode is further less likely to occur, and the conduction reliability and the connection reliability are effectively increased.

  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 a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, a tin-zinc alloy, and a tin-indium alloy. The low melting point metal is preferably tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, or a tin-indium alloy because of its excellent wettability with respect to the electrode. More preferred are a tin-bismuth alloy and 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 terms. Examples of the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. A tin-indium system (117 ° C eutectic) or a tin-bismuth system (139 ° C eutectic) that has a low melting point and is free of lead is preferable. That is, the solder particles preferably do not contain lead, and preferably contain tin and indium, or contain tin and bismuth.

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

  The average particle diameter of the solder particles is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, particularly preferably 5 μm or more, preferably 100 μm or less, more preferably 60 μm or less, and even more preferably 40 μm. Hereinafter, it is more preferably 30 μm or less, still more preferably 20 μm or less, particularly preferably 15 μm or less, and most preferably 10 μm or less. When the average particle diameter 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 more efficiently arranged on the electrode. The average particle diameter of the solder particles is particularly preferably 3 μm or more and 30 μm or less.

  The “average particle diameter” of the solder particles indicates a number average particle diameter. The average particle diameter of the solder particles is obtained, for example, by observing 50 arbitrary solder particles with an electron microscope or an optical microscope, calculating an average value, or performing laser diffraction particle size distribution measurement.

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

  The coefficient of variation (CV value) is expressed by the following equation.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of particle diameter of solder particles Dn: Average value of particle diameter of solder particles

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

  The content of the solder particles in 100% by weight of the conductive material is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, particularly preferably 20% by weight or more, and most preferably 30%. % By weight or more, preferably 90% by weight or less, more preferably 80% by weight or less, still more preferably 60% by weight or less, and particularly preferably 50% by weight or less. When the content of the solder particles is not less than the above lower limit and not more than the above upper limit, it is possible to more efficiently arrange the solder particles on the electrodes, and it is easy to arrange many solder particles between the electrodes, The conduction reliability is further increased. From the viewpoint of further improving the conduction reliability, it is preferable that the content of the solder particles is large.

  When the line (L) where the electrode is formed is 50 μm or more and less than 150 μm, the content of the solder particles is preferably 100% by weight of the conductive material from the viewpoint of further improving the conduction reliability. Is 20% by weight or more, more preferably 30% by weight or more, preferably 55% by weight or less, more preferably 45% by weight or less.

  From the viewpoint of further improving the conduction reliability when the space (S) where the electrode is not formed is 50 μm or more and less than 150 μm, the content of the solder particles is preferably 100% by weight of the conductive material. Is 30% by weight or more, more preferably 40% by weight or more, preferably 70% by weight or less, more preferably 60% by weight or less.

  When the line (L) where the electrode is formed is 150 μm or more and less than 1000 μm, the content of the solder particles is preferably 100% by weight of the conductive material from the viewpoint of further improving the conduction reliability. Is 30% by weight or more, more preferably 40% by weight or more, preferably 70% by weight or less, more preferably 60% by weight or less.

  From the viewpoint of further improving the conduction reliability when the space (S) where the electrode is not formed is 150 μm or more and less than 1000 μm, the content of the solder particles is preferably 100% by weight of the conductive material. Is 30% by weight or more, more preferably 40% by weight or more, preferably 70% by weight or less, more preferably 60% by weight or less.

(Thermosetting compound: thermosetting component)
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, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. From the viewpoint of further improving the curability and viscosity of the conductive material and further improving the connection reliability, an epoxy compound is preferable.

  The content of the thermosetting compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight or less. Is 98% by weight or less, more preferably 90% by weight or less, and particularly preferably 80% by weight or less. From the viewpoint of further improving the impact resistance, it is preferable that the content of the thermosetting component is large.

(Thermosetting agent: thermosetting component)
The thermosetting agent thermosets the thermosetting compound. Examples of the thermosetting agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, and other thiol curing agents, acid anhydrides, thermal cation initiators (thermal cation curing agents), and thermal radical generators. It is done. As for the said thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  An imidazole curing agent, a thiol curing agent, or an amine curing agent is preferable because the conductive material can be cured more rapidly at a low temperature. Moreover, since a storage stability becomes high when the curable compound curable by heating and the thermosetting agent are mixed, a latent curing agent is preferable. The latent curing agent is preferably a latent imidazole curing agent, a latent thiol curing agent, or a latent amine curing agent. In addition, the said thermosetting agent may be coat | covered with polymeric substances, such as a polyurethane resin or a polyester resin.

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

  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 hexamethylene diamine, octamethylene diamine, decamethylene diamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5.5]. Examples include undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine, and diaminodiphenylsulfone.

  Examples of the thermal cation initiator include iodonium cation curing agents, oxonium cation curing agents, and sulfonium cation curing agents. Examples of the iodonium-based cationic curing agent include bis (4-tert-butylphenyl) iodonium hexafluorophosphate. 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). Examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

  The reaction initiation temperature of the thermosetting agent is preferably 50 ° C or higher, more preferably 70 ° C or higher, still more preferably 80 ° C or higher, preferably 250 ° C or lower, more preferably 200 ° C or lower, still more preferably 150 ° C or lower, Especially preferably, it is 140 degrees C or less. When the reaction start temperature of the thermosetting agent is not less than the above lower limit and not more than the above upper limit, the solder particles are more efficiently arranged on the electrode. The reaction initiation temperature of the thermosetting agent is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

  From the viewpoint of more efficiently arranging the solder on the electrode, the reaction initiation temperature of the thermosetting agent is preferably higher than the melting point of the solder in the solder particles, more preferably 5 ° C. or more, more preferably 10 It is more preferable that the temperature is higher than ° C.

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

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, preferably 200 parts by weight or less, more preferably 100 parts by weight with respect to 100 parts by weight of the thermosetting compound. Part or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is not less than the above lower limit, it is easy to sufficiently cure the conductive material. When the content of the thermosetting agent is not more than the above upper limit, it is difficult for an excess thermosetting agent that did not participate in curing after curing to remain, and the heat resistance of the cured product is further enhanced.

(flux)
The conductive material preferably contains a flux. By using flux, the solder can be more effectively placed on the electrode. The flux is not particularly limited. As the flux, a flux generally used for soldering 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, hydrazine, an organic acid, and pine resin. Etc. As for the said flux, only 1 type may be used and 2 or more types may be used together.

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

  The rosin is a rosin composed mainly of abietic acid. The flux is preferably rosins, and more preferably abietic acid. By using this preferable flux, the conduction reliability between the electrodes is further enhanced.

  From the viewpoint of effectively increasing the conduction reliability between the electrodes, the flux preferably has two or more carboxyl groups, and the flux more preferably has three or more carboxyl groups.

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

  Examples of the flux having a melting point of 80 ° C. or higher and 190 ° C. or lower include succinic acid (melting point 186 ° C.), glutaric acid (melting point 96 ° C.), adipic acid (melting point 152 ° C.), pimelic acid (melting point 104 ° C.), suberic acid Examples thereof include dicarboxylic acids such as (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), and malic acid (melting point 130 ° C.).

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

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

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

  When the melting point of the flux is higher than the melting point of the solder, the solder particles can be efficiently aggregated on the electrode portion. This is because, when heat is applied at the time of joining, when the electrode formed on the connection target member is compared with the portion of the connection target member around the electrode, the thermal conductivity of the electrode portion is that of the connection target member portion around the electrode. Due to the fact that it is higher than the thermal conductivity, the temperature rise of the electrode portion is fast. At the stage where the melting point of the solder particles is exceeded, the inside of the solder particles dissolves, but the oxide film formed on the surface does not reach the melting point (activation temperature) of the flux and is not removed. In this state, since the temperature of the electrode portion first reaches the melting point (activation temperature) of the flux, the oxide film on the surface of the solder particles preferentially on the electrode is removed, and the solder particles are placed on the surface of the electrode. Can spread wet. Thereby, solder particles can be efficiently aggregated on the electrode.

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

  The flux is preferably a flux that releases cations by heating. By using a flux that releases cations upon heating, the solder particles can be arranged more efficiently on the electrode.

  The content of the flux in 100% by weight of the conductive material is preferably 0.5% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. The conductive material may not contain flux. When the flux content 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 the oxide film formed on the surface of the solder and the electrode is more effective. Can be removed.

(Filler)
A filler may be added to the conductive material. The filler may be an organic filler or an inorganic filler. By adding the filler, the distance at which the solder particles aggregate can be suppressed, and the solder particles can be uniformly aggregated on all the electrodes of the substrate.

  The content of the filler in 100% by weight of the conductive material is preferably 0% by weight or more, preferably 5% by weight or less, more preferably 2% by weight or less, and further preferably 1% by weight or less. 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 more efficiently arranged on the electrode.

(Other ingredients)
The conductive material may be, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, and a lubricant as necessary. In addition, various additives such as an antistatic agent and a flame retardant may be included.

(Connection structure and method of manufacturing connection structure)
A connection structure according to the present invention includes a first connection target member having at least one first electrode on the surface, a second connection target member having at least one second electrode on the surface, and the first The connection object member and the connection part which has connected the said 2nd connection object member are provided. In the connection structure according to the present invention, the connection portion is formed of the anisotropic conductive material described above. 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 manufacturing method of the connection structure according to the present invention uses the above-described anisotropic conductive material to provide the anisotropic conductive material on the surface of the first connection target member having at least one first electrode on the surface. A step of disposing a material, and a second connection target member having at least one second electrode on the surface opposite to the first connection target member side of the anisotropic conductive material, A step of arranging the first electrode and the second electrode to face each other, and heating the anisotropic conductive material to a temperature equal to or higher than a melting point of the solder particles and a temperature equal to or higher than a curing temperature of the thermosetting component, The connecting portion connecting the first connection target member and the second connection target member is formed of the anisotropic conductive material, and the first electrode and the second electrode are formed. And a step of electrically connecting with a solder portion in the connection portion.

  In the connection structure according to the present invention and the method for manufacturing the connection structure according to the present invention, since a specific anisotropic conductive material is used, a plurality of solder particles are disposed between the first electrode and the second electrode. The plurality of solder particles can be efficiently arranged on the electrode (line). Moreover, it is difficult for some of the plurality of solder particles to be disposed in a region (space) where no electrode is formed, and the amount of solder particles disposed in a region where no electrode is formed can be considerably reduced. Therefore, the conduction reliability between the first electrode and the second electrode can be improved. In addition, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, and to improve insulation reliability.

  In order to arrange a plurality of solder particles efficiently on the electrode and to considerably reduce the amount of the solder particles arranged in the region where the electrode is not formed, an anisotropic conductive film is used instead of an anisotropic conductive film. The present inventors have found that it is desirable to use a conductive conductive paste.

  In the present invention, another method of efficiently collecting a plurality of solder particles between the electrodes may be further employed. As a method for efficiently collecting a plurality of solder particles between electrodes, when heat is applied to the conductive material between the first connection target member and the second connection target member, the viscosity of the conductive material by heat is applied. The method of generating the convection of the electrically-conductive material between a 1st connection object member and a 2nd connection object member, etc. are mentioned because it falls. In this method, a method of generating convection due to a difference in heat capacity between the electrode on the surface of the connection target member and the other surface member, a method of generating convection as water vapor from the heat of the connection target member, and the first Examples include a method of generating convection due to a temperature difference between the connection target member and the second connection target member. Thereby, the solder particles in the conductive material can be efficiently moved to the surface of the electrode.

  In the present invention, a method of selectively aggregating solder particles on the surface of the electrode may be further employed. As a method of selectively agglomerating solder particles on the surface of the electrode, there is a connection target member formed of an electrode material having good wettability of molten solder particles and another surface material having poor wettability of molten solder particles. A method of selectively adhering molten solder particles that have reached the surface of the electrode to the electrode and then melting and adhering another solder particle to the molten solder particles, and an electrode material with good thermal conductivity And other surface materials with poor thermal conductivity are selected, and when heat is applied, the temperature of the electrode is raised relative to the other surface members to selectively In this method, the solder particles are selectively agglomerated on the electrodes by using solder particles that have been treated so as to have a positive charge with respect to the negative charges existing on the electrode formed of metal. Method of, and, the electrode having a hydrophilic metal surface, the resin other than the solder particles of the conductive material by a hydrophobic, a method to aggregate selectively solder particles on the electrode, and the like.

  The thickness of the solder part between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, preferably 100 μm or less, more preferably 80 μm or less. The solder wetted area on the surface of the electrode (area where the solder is in contact with 100% of the exposed area of the electrode) is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, preferably 100. % Or less.

  In the method for manufacturing a connection structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection portion, no pressure is applied, and the second connection is applied to the conductive material. The weight of the target member is added, or pressure is applied in at least one of the step of arranging the second connection target member and the step of forming the connection portion, and the second connection target member It is preferable that the pressure of pressurization is less than 1 MPa in both the step of disposing and the step of forming the connecting portion. By not applying a pressure of 1 MPa or more, the aggregation of solder particles is considerably promoted. From the viewpoint of suppressing the warpage of the connection target member, in the method for manufacturing a connection structure according to the present invention, at least one of the step of arranging the second connection target member and the step of forming the connection portion is performed. The pressure of pressurization may be less than 1 MPa in both the step of performing pressure and arranging the second connection target member and the step of forming the connection portion. When pressurization is performed, the pressurization may be performed only in the step of arranging the second connection target member, or the pressurization may be performed only in the step of forming the connection portion. Pressurization may be performed in both the step of arranging the connection target member and the step of forming the connection portion. The case where the pressure is less than 1 MPa includes the case where no pressure is applied. When pressurizing, the pressure of pressurization is preferably 0.9 MPa or less, more preferably 0.8 MPa or less. When the pressure of the pressurization is 0.8 MPa or less, the aggregation of the solder particles is further promoted more remarkably than when the pressure of the pressurization exceeds 0.8 MPa.

  In the method for manufacturing a connection structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection portion, no pressure is applied, and the second connection is applied to the conductive material. The weight of the target member is preferably 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 weight force of the second connection target member. It is preferable that no pressure is applied. In these cases, the uniformity of the amount of solder can be further enhanced in the plurality of solder portions. Furthermore, the thickness of the solder portion can be increased more effectively, and a plurality of solder particles can be easily collected between the electrodes, and the plurality of solder particles can be arranged more efficiently on the electrodes (lines). it can. Moreover, it is difficult for some of the plurality of solder particles to be arranged in a region (space) where no electrode is formed, and the amount of solder particles arranged in a region where no electrode is formed can be further reduced. Therefore, the conduction reliability between the electrodes can be further enhanced. In addition, the electrical connection between the laterally adjacent electrodes that should not be connected can be further prevented, and the insulation reliability can be further improved.

  Furthermore, in the step of arranging the second connection target member and the step of forming the connection portion, if the weight of the second connection target member is added to the conductive material without applying pressure, the connection portion is Solder particles arranged in a region (space) where no electrode is formed before being formed are more easily collected between the first electrode and the second electrode, and a plurality of solder particles are separated into electrodes (lines). The inventor has also found that the arrangement can be made more efficient. In the present invention, a configuration in which a conductive paste is used instead of a conductive film and a configuration in which the weight of the second connection target member is added to the conductive paste without applying pressure are used in combination. This has a great meaning in order to obtain the effects of the present invention at a higher level.

  In addition, WO2008 / 023452A1 describes that it is preferable to pressurize with a predetermined pressure at the time of bonding from the viewpoint of efficiently moving the solder powder to the electrode surface, and the pressurizing pressure further ensures the solder area. For example, it is described that the pressure is set to 0 MPa or more, preferably 1 MPa or more. Further, even if the pressure intentionally applied to the adhesive tape is 0 MPa, the member disposed on the adhesive tape It is described that a predetermined pressure may be applied to the adhesive tape by its own weight. In WO2008 / 023452A1, it is described that the pressure applied intentionally to the adhesive tape may be 0 MPa, but there is no difference between the effect when the pressure exceeding 0 MPa is applied and when the pressure is set to 0 MPa. Not listed. In addition, WO2008 / 023452A1 recognizes nothing about the importance of using a paste-like conductive paste instead of a film.

  Moreover, if a conductive paste is used instead of a conductive film, it becomes easy to adjust the thickness of the connection part and the solder part depending on the amount of the conductive paste applied. On the other hand, in the conductive film, in order to change or adjust the thickness of the connection portion, it is necessary to prepare a conductive film having a different thickness or to prepare a conductive film having a predetermined thickness. There is. Further, the conductive film has a problem that the melt viscosity of the conductive film cannot be sufficiently lowered at the melting temperature of the solder, 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 using an anisotropic conductive material according to an embodiment of the present invention.

  The connection structure 1 shown in FIG. 1 is a connection that connects a first connection target member 2, a second connection target member 3, and the first connection target member 2 and the second connection target member 3. Part 4. The connection part 4 is formed of a conductive material including a thermosetting compound, a thermosetting agent, and a plurality of solder particles. The material of the connection portion 4 is the conductive material. The connection part 4 is a cured product of the conductive material. The thermosetting compound and the thermosetting agent are thermosetting components.

  The connection portion 4 includes a solder portion 4A in which a plurality of solder particles are gathered and joined to each other, and a cured product portion 4B in which a thermosetting component is thermally cured.

  The first connection target member 2 has a plurality of first electrodes 2a on the surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by the solder portion 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by the solder portion 4A. In the connection portion 4, no solder exists 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 an area different from the solder part 4A (hardened product part 4B part), there is no solder separated from the solder part 4A. If the amount is small, the solder 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. In addition, it is preferable that the solder has spread on the surface of the electrode, and the solder does not necessarily have to be gathered between the upper and lower electrodes.

  As shown in FIG. 1, in the connection structure 1, a plurality of solder particles gather between the first electrode 2 a and the second electrode 3 a, and after the plurality of solder particles melt, After the electrode surface wets and spreads, it solidifies to form the solder portion 4A. For this reason, the connection area of 4 A of solder parts and the 1st electrode 2a, and 4 A of solder parts, and the 2nd electrode 3a becomes large. That is, by using the solder particles, the solder portion 4A, the first electrode 2a, and the solder portion are compared with the case where the conductive outer surface is made of a metal such as nickel, gold or copper. The contact area between 4A and the second electrode 3a increases. For this reason, the conduction | electrical_connection reliability and connection reliability in the connection structure 1 become high. Note that the conductive paste may contain a flux. When the flux is used, the flux is generally deactivated gradually by heating.

  In addition, in the connection structure 1 shown in FIG. 1, all the solder parts 4A are located in the area | region which the 1st, 2nd electrodes 2a and 3a oppose. The connection structure 1X of the modification shown in FIG. 3 is different from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. The connection part 4X has the solder part 4XA and the hardened | cured material part 4XB. As in the connection structure 1X, most of the solder portions 4XA are located in regions where the first and second electrodes 2a and 3a are opposed to each other, and a part of the solder portion 4XA is first and second. You may protrude to the side from the area | region which electrode 2a, 3a has opposed. The solder part 4XA protruding laterally from the region where the first and second electrodes 2a and 3a are opposed is a part of the solder part 4XA and is not a solder separated from the solder part 4XA. In the present embodiment, the amount of solder away from the solder portion can be reduced, but the solder away from the solder portion may exist in the cured product portion.

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

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

  From the viewpoint of further improving the conduction reliability, the first electrode and the second electrode are opposed to each other in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode. When the matching portion is viewed, the portion where the first electrode and the second electrode face each other is 70% or more (more preferably 80% or more, more preferably 90%) of the solder portion in the connection portion. In particular, it is preferable that 95% or more, most preferably 99% or more) is disposed.

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

  First, the 1st connection object member 2 which has the 1st electrode 2a on the surface (upper surface) is prepared. Next, as shown in FIG. 2A, a conductive material 11 (anisotropic conductive material) including a thermosetting component 11B and a plurality of solder particles 11A on the surface of the first connection target member 2 is used. Is arranged (first step). In the present embodiment, the conductive material 11 is a conductive paste. The conductive material 11 is disposed on the surface of the first connection target member 2 on which the first electrode 2a is provided. After the conductive material 11 is disposed, the solder particles 11A are disposed both on the first electrode 2a (line) and on a region (space) where the first electrode 2a is not formed.

  The method for arranging the conductive paste is not particularly limited, and examples thereof include application using a dispenser, screen printing, and ejection using an inkjet device.

  Moreover, the 2nd connection object member 3 which has the 2nd electrode 3a on the surface (lower surface) is prepared. Next, as shown in FIG. 2B, in the conductive material 11 on the surface of the first connection target member 2, on the surface opposite to the first connection target member 2 side of the conductive material 11, The 2nd connection object member 3 is arrange | positioned (2nd process). On the surface of the conductive material 11, the second connection target member 3 is disposed 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 and above the curing temperature of the thermosetting component 11B (third step). That is, the conductive material 11 is heated to a temperature higher than the melting point of the solder particles 11A and the curing temperature of the thermosetting component 11B. At the time of this heating, the solder particles 11A that existed in the region where no electrode is formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). In the present embodiment, since the conductive paste is used instead of the conductive film, the conductive paste further has a specific configuration. Therefore, the solder particles 11A are disposed between the first electrode 2a and the second electrode 3a. To gather effectively. Also, the solder particles 11A are melted and joined together. Further, the thermosetting component 11B is thermoset. As a result, as shown in FIG. 2C, the connection portion 4 that connects the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. The connection part 4 is formed of the conductive material 11, the solder part 4A is formed by joining a plurality of solder particles 11A, and the cured part 4B is formed by thermosetting the thermosetting component 11B. If the solder particles 11A are sufficiently moved, the first electrode 2a and the second electrode are moved after the movement of the solder particles 11A not located between the first electrode 2a and the second electrode 3a starts. It is not necessary to keep the temperature constant until the movement of the solder particles 11A is completed.

  In the present embodiment, no pressure is applied in the second step and the third step. In the present embodiment, the weight of the second connection target member 3 is added to the conductive material 11. For this reason, when the connection part 4 is formed, the solder particles 11A are effectively collected between the first electrode 2a and the second electrode 3a. In addition, if pressure is applied in at least one of the second step and the third step, the action of the solder particles trying to collect between the first electrode and the second electrode is hindered. The tendency to become higher. This has been found by the inventor.

  Moreover, in this embodiment, since pressurization is not performed, when the second connection target member is superimposed on the first connection target member to which the conductive material is applied, the electrode of the first connection target member Even when the first connection target member and the second connection target member are overlapped in a state where the alignment with the electrode of the second connection target member is shifted, the shift is corrected and the first connection target is corrected. It is possible to connect the electrode of the member and the electrode of the second connection target member (self-alignment effect). This is because the molten solder self-aggregated between the electrode of the first connection target member and the electrode of the second connection target member is the electrode of the first connection target member and the electrode of the second connection target member. As the area where the solder and the other components of the conductive material are in contact with each other is minimized, the energy becomes more stable. Therefore, the force that makes the connection structure with alignment, which is the connection structure with the smallest area, works. Because. At this time, it is desirable that the conductive material is not cured and that the viscosity of components other than the solder particles of the conductive material is sufficiently low at that temperature and time.

  The viscosity of the conductive material at the melting point of the solder is preferably 50 Pa · s or less, more preferably 10 Pa · s or less, still more preferably 1 Pa · s or less, preferably 0.1 Pa · s or more, more preferably 0.2 Pa · s. s or more. If the viscosity is below the above upper limit, the solder particles can be efficiently aggregated. If the viscosity is above the above lower limit, voids at the connection part are suppressed, and the overflow of the conductive material outside the connection part is suppressed. can do.

  The viscosity of the conductive material at the melting point of the solder is measured as follows.

  The viscosity of the conductive material at the melting point of the solder is as follows: STRESSTECH (manufactured by EOLOGICA), etc., strain control 1 rad, frequency 1 Hz, temperature rising rate 20 ° C./min, measurement temperature range 25-200 ° C. When the melting point exceeds 200 ° C., the upper limit of the temperature is taken as the melting point of the solder). From the measurement results, the viscosity at the melting point (° C.) of the solder is evaluated.

  In this way, the connection structure 1 shown in FIG. 1 is obtained. The second step and the third step may be performed continuously. Moreover, after performing the said 2nd process, the laminated body of the 1st connection object member 2, the electrically-conductive material 11, and the 2nd connection object member 3 which are obtained is moved to a heating part, and the said 3rd connection object is carried out. You may perform a process. In order to perform the heating, the laminate may be disposed on a heating member, or the laminate may be disposed in a heated space.

  The heating temperature in the third step is not particularly limited as long as it is not lower than the melting point of the solder particles and not lower than the curing temperature of the thermosetting component. The heating temperature is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, preferably 450 ° C. or lower, more preferably 250 ° C. or lower, and still more preferably 200 ° C. or lower.

  In addition, after the said 3rd process, a 1st connection object member or a 2nd connection object member can be peeled from a connection part for the purpose of correction of a position or re-production. The heating temperature for performing this peeling is preferably not lower than the melting point of the solder particles, more preferably not lower than the melting point (° C.) of the solder particles + 10 ° C. The heating temperature for performing this peeling may be the melting point (° C.) of the solder particles + 100 ° C. or less.

  As the heating method in the third step, a method of heating the entire connection structure using a reflow furnace or an oven above the melting point of the solder particles and the curing temperature of the thermosetting component, or a connection structure The method of heating only the connection part of a body locally is mentioned.

  As a tool used for the method of heating locally, a hot plate, a heat gun for applying hot air, a soldering iron, an infrared heater, and the like can be given.

  In addition, when heating locally with a hot plate, the metal directly under the connection is made of a metal with high thermal conductivity, and other places where heating is not preferred are made of a material with low thermal conductivity such as a fluororesin. The upper surface of the hot plate is preferably formed.

  The said 1st, 2nd connection object member is not specifically limited. Specifically as said 1st, 2nd connection object member, electronic components, such as a semiconductor chip, a semiconductor package, LED chip, LED package, a capacitor | condenser, a diode, and a resin film, a printed circuit board, a flexible printed circuit board, flexible Examples 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.

  Since the conduction reliability between electrodes can be effectively increased by the present invention, at least one of the first connection object member and the second connection object member is a semiconductor chip, a resin film, or a flexible printed circuit board. A flexible flat cable or a rigid flexible substrate is preferable. Since the conduction reliability between the electrodes can be effectively increased by the present invention, the second connection target member is preferably a semiconductor chip, a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. .

  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 board, a flexible flat cable, or a rigid flexible board. The second connection target member is preferably a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. Resin films, flexible printed boards, flexible flat cables, and rigid flexible boards have the property of being highly flexible and relatively lightweight. When a conductive film is used for connection of such a connection object member, there exists a tendency for a solder particle not to gather on an electrode. On the other hand, even if a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board is used, by using a conductive paste, solder particles can be efficiently collected on the electrodes, and conduction between the electrodes. Reliability can be sufficiently increased. When using a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board, compared to the case of using other connection target members such as a semiconductor chip, the conduction reliability between the electrodes by not applying pressure is improved. The improvement effect can be obtained more effectively.

  Peripherals, area arrays, etc. exist in the form of the connection object member. As a feature of each member, in the peripheral substrate, the electrodes are present only on the outer peripheral portion of the substrate. In the area array substrate, there are electrodes in the plane.

  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 object member is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient and the electrode by which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the material for 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.

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

Polymer A:
Synthesis of reaction product (polymer A) of bisphenol F with 1,6-hexanediol diglycidyl ether and bisphenol F type epoxy resin:
Bisphenol F (containing 4,4′-methylene bisphenol, 2,4′-methylene bisphenol and 2,2′-methylene bisphenol in a weight ratio of 2: 3: 1) 100 parts by weight, 1,6-hexanediol Three parts: 130 parts by weight of glycidyl ether, 5 parts by weight of bisphenol F type epoxy resin (“EPICLON EXA-830CRP” manufactured by DIC), and 10 parts by weight of resorcinol type epoxy compound (“EX-201” manufactured by Nagase ChemteX) It put into the neck flask and it was made to melt | dissolve at 100 degreeC under nitrogen flow. Thereafter, 0.15 part by weight of triphenylbutylphosphonium bromide, which is a catalyst for addition reaction of hydroxyl group and epoxy group, was added and subjected to an addition polymerization reaction at 140 ° C. for 4 hours under a nitrogen flow to obtain a reaction product (Polymer A). )

  By confirming that the addition polymerization reaction has progressed by NMR, the reaction product (polymer A) is composed of a hydroxyl group derived from bisphenol F, 1,6-hexanediol diglycidyl ether, and an epoxy group of bisphenol F type epoxy resin. It was confirmed that it has a structural unit bonded to the main chain and has an epoxy group at both ends.

  The reaction product (polymer A) obtained by GPC had a weight average molecular weight of 28,000 and a number average molecular weight of 8,000.

  Polymer B: both end epoxy group rigid skeleton phenoxy resin, “YX6900BH45” manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 16000

  Thermosetting compound 1: Resorcinol type epoxy compound, “EX-201” manufactured by Nagase ChemteX Corporation

  Thermosetting compound 2: Epoxy compound, “EXA-4850-150” manufactured by DIC

  Thermosetting agent 1: Trimethylolpropane tris (3-mercaptopropinate), “TMMP” manufactured by SC Organic Chemical Co., Ltd.

  Latent epoxy thermosetting agent 1: “Fujicure 7000” manufactured by T & K TOKA

  Flux 1: glutaric acid, manufactured by Wako Pure Chemical Industries, melting point (activation temperature) 95 ° C., pKa1 = 4.13

  Flux 2: Pimelic acid, manufactured by Wako Pure Chemical Industries, Ltd., melting point (activity temperature) 103 ° C., pKa1 = 4.31

Method for producing solder particles 1:
Solder particles having anionic polymer 1: 200 g of solder particle body, 40 g of pimelic acid (pKa2 = 5.08), and 70 g of acetone are weighed in a three-necked flask, and then the hydroxyl group and pimelic acid on the surface of the solder particle body 0.3 g of dibutyltin oxide which is a dehydration condensation catalyst with the carboxyl group of was added and reacted at 60 ° C. for 4 hours. Thereafter, the solder particles were collected by filtration.

  The collected solder particles, 50 g of pimelic acid, 200 g of toluene, and 0.3 g of paratoluenesulfonic acid were weighed in a three-necked flask and allowed to react at 120 ° C. for 3 hours while evacuating and refluxing. . At this time, the reaction was carried out while removing water produced by dehydration condensation using a Dean-Stark extraction device.

  Thereafter, the solder particles were collected by filtration, washed with hexane, and dried. Thereafter, the obtained solder particles were crushed with a ball mill, and then a sieve was selected so as to obtain a predetermined CV value.

(Zeta potential measurement)
Further, 0.05 g of the obtained solder particles were put in 10 g of methanol and subjected to ultrasonic treatment to uniformly disperse to obtain a dispersion. The zeta potential was measured by electrophoretic measurement using this dispersion and “Delsamax PRO” manufactured by Beckman Coulter.

(Measurement of acid dissociation constant pKa)
Titration was performed with NaOH using a potentiometric automatic titrator AT-610 (manufactured by Kyoto Electronics Industry Co., Ltd.), and the acid dissociation constant was determined from the obtained titration curve.

(Weight average molecular weight of anionic polymer)
The weight average molecular weight of the anionic polymer 1 on the surface of the solder particles was obtained by dissolving the solder using 0.1N hydrochloric acid, collecting the polymer by filtration, and determining by GPC.

(CV value of particle diameter of solder particles)
The CV value was measured with a laser diffraction particle size distribution analyzer (“LA-920” manufactured by Horiba, Ltd.).

  Solder particle 1 (SnBi solder particle, melting point 139 ° C., solder particle body selected from “DS10” manufactured by Mitsui Kinzoku Co., Ltd., surface-treated solder particle having anionic polymer 1, average particle diameter: 13 μm, CV value: (20%, surface zeta potential: +0.48 mV, polymer molecular weight: Mw = 7000)

  Solder particles 2: Solder particles 2 were prepared in the same manner except that pimelic acid was changed to oxalic acid (pKa2 = 3.82) in the method for producing solder particles 1.

  Solder particles 3: Solder particles 3 were prepared in the same manner except that pimelic acid was changed to malic acid (pKa2 = 4.71) by the method for producing solder particles 1.

  Conductive particles 1: A copper layer having a thickness of 1 μm is formed on the surface of the resin particles, and a solder layer having a thickness of 3 μm (tin: bismuth = 42 wt%: 58 wt%) is formed on the surface of the copper layer. Conductive particles

Production method of conductive particles 1:
Divinylbenzene resin particles having an average particle diameter of 10 μm (“Micropearl SP-210” manufactured by Sekisui Chemical Co., Ltd.) were subjected to electroless nickel plating to form a base nickel plating layer having a thickness of 0.1 μm on the surface of the resin particles. Next, the resin particles on which the base nickel plating layer was formed were subjected to electrolytic copper plating to form a 1 μm thick copper layer. Furthermore, electrolytic plating was performed using an electrolytic plating solution containing tin and bismuth to form a solder layer having a thickness of 3 μm. In this way, a 1 μm thick copper layer is formed on the surface of the resin particles, and a 3 μm thick solder layer (tin: bismuth = 42 wt%: 58 wt%) is formed on the surface of the copper layer. Conductive particles 1 were prepared.

(Examples 1-5 and Comparative Examples 1-3)
(1) Preparation of anisotropic conductive paste The components shown in Table 1 below were blended in the blending amounts shown in Table 1 to obtain anisotropic conductive paste.

(2) Fabrication of first connection structure (L / S = 200 μm / 800 μm) Glass epoxy substrate having a L / S of 200 μm / 800 μm and an electrode length of 3 mm on a copper electrode pattern (copper electrode thickness 12 μm) on the upper surface (FR-4 substrate) (first connection target member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (thickness of copper electrode 12 micrometers) of L / S of 200 micrometers / 800 micrometers and electrode length 1mm on the lower surface was prepared.

  The overlapping area of the glass epoxy substrate and the flexible printed circuit board was 1.5 cm × 3 mm, and the number of connected electrodes was 14 pairs.

  On the upper surface of the glass epoxy substrate, the anisotropic conductive paste immediately after production is applied by screen printing using a metal mask so that the thickness is 100 μm on the electrode of the glass epoxy substrate, and anisotropic conductive A paste layer was formed. Next, the flexible printed circuit board was laminated on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other. At this time, no pressure was applied. The weight of the flexible printed board is added to the anisotropic conductive paste layer. Thereafter, while heating the anisotropic conductive paste layer to 190 ° C., the solder is melted, and the anisotropic conductive paste layer is cured at 190 ° C. for 10 seconds. Obtained.

(3) Fabrication of Second Connection Structure (L / S = 500 μm / 500 μm) Glass epoxy substrate having a copper electrode pattern (copper electrode thickness 12 μm) with L / S of 500 μm / 500 μm and electrode length of 3 mm on the upper surface (FR-4 substrate) (first connection target member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (thickness of a copper electrode 12 micrometers) of L / S 500 micrometers / 500 micrometers and electrode length 1mm on the lower surface was prepared.

  A second connection structure was obtained in the same manner as the production of the first connection structure except that the glass epoxy substrate and the flexible printed circuit board having different L / S were used.

(4) Production of third connection structure (L / S = 800 μm / 200 μm) Glass epoxy board having a copper electrode pattern (copper electrode thickness 12 μm) having an L / S of 800 μm / 200 μm and an electrode length of 3 mm on the upper surface (FR-4 substrate) (first connection target member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (thickness of copper electrode 12 micrometers) of L / S of 800 micrometers / 200 micrometers and electrode length 1mm on the lower surface was prepared.

  A third connection structure was obtained in the same manner as the production of the first connection structure except that the glass epoxy substrate and the flexible printed circuit board having different L / S were used.

(Evaluation)
(1) Viscosity at 25 ° C. The viscosity (η25) of the anisotropic conductive paste at 25 ° C. was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. and 5 rpm.

(2) Viscosity at the melting point of the solder Using the STRESSTECH (manufactured by EOLOGICA), etc., the viscosity of the conductive material at the melting point of the solder is 1 rad, frequency 1 Hz, heating rate 20 ° C./min, measurement temperature range It was measured under conditions of 25 to 200 ° C. (however, when the melting point of the solder exceeds 200 ° C., the upper temperature limit is the melting point of the solder).

(3) Thickness of solder part By observing a cross section of the obtained connection structure, the thickness of the solder part located between the upper and lower electrodes was evaluated.

(4) Solder placement accuracy on electrode 1
In the obtained first, second, and third connection structures, a portion where 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 is provided. When viewed, the ratio X of the area where the solder portion in the connection portion is arranged in the area of 100% of the portion where the first electrode and the second electrode face each other was evaluated. The solder placement accuracy 1 on the electrode was determined according to the following criteria.

[Criteria for solder placement accuracy 1 on electrode]
○○: 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% X: Ratio X is less than 50%

(5) Solder placement accuracy on electrode 2
In the obtained first, second, and third connection structures, the first electrode and the second electrode are opposed to 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 mating part, the ratio Y of the solder part in the connecting part arranged in the part where the first electrode and the second electrode face each other in 100% of the solder part in the connecting part was evaluated. . The solder placement accuracy 2 on the electrode was determined according to the following criteria.

[Criteria for solder placement accuracy 2 on electrode]
◯: Ratio Y is 99% or more ○: Ratio Y is 90% or more and less than 99% △: Ratio Y is 70% or more and less than 90% X: Ratio Y is less than 70%

(6) Conduction reliability between upper and lower electrodes In the obtained first, second, and third connection structures (n = 15), the connection resistance per connection portion between the upper and lower electrodes is 4 respectively. It was measured by the terminal method. The average value of connection resistance was calculated. Note that the connection resistance can be obtained by measuring the voltage when a constant current is passed from the relationship of voltage = current × resistance. The conduction reliability was determined according to the following criteria.

[Judgment criteria for conduction reliability]
◯: Average connection resistance is 50 mΩ or less ○: Average connection resistance exceeds 50 mΩ, 70 mΩ or less △: Average connection resistance exceeds 70 mΩ, 100 mΩ or less ×: Average connection resistance exceeds 100 mΩ Or there is a bad connection

(7) Insulation reliability between adjacent electrodes In the obtained first, second, and third connection structures (n = 15), they are left in an atmosphere of 121 ° C. and 100% humidity for 100 hours and then adjacent to each other. 5V was applied between the electrodes to be measured, and the resistance value was measured at 25 locations. Insulation reliability was judged according to the following criteria.

[Criteria for insulation reliability]
◯: Average value of connection resistance is 10 ⁷ Ω or more ○: Average value of connection resistance is 10 ⁶ Ω or more, less than 10 ⁷ Ω △: Average value of connection resistance is 10 ⁵ Ω or more, less than 10 ⁶ Ω ×: Connection The average resistance is less than 10 ⁵ Ω

(8) Position shift between upper and lower electrodes In the obtained first, second, and third connection structures, the first electrode and the second electrode are stacked in the stacking direction of the first electrode, the connection portion, and the second electrode. Whether the center line of the first electrode and the center line of the second electrode were aligned when the portion facing the two electrodes was viewed, and the distance of the positional deviation were evaluated. The positional deviation between the upper and lower electrodes was determined according to the following criteria.

[Criteria for misregistration between upper and lower electrodes]
○: Misalignment is less than 15 μm ○: Misalignment is 15 μm or more and less than 25 μm Δ: Misalignment is 25 μm or more and less than 40 μm ×: Misalignment is 40 μm or more

  The results are shown in Table 1 below.

  The same tendency was observed when a resin film, a flexible flat cable, and a rigid flexible board were used instead of the flexible printed board.

DESCRIPTION OF SYMBOLS 1,1X ... Connection structure 2 ... 1st connection object member 2a ... 1st electrode 3 ... 2nd connection object member 3a ... 2nd electrode 4, 4X ... Connection part 4A, 4XA ... Solder part 4B, 4XB ... Cured part 11 ... Anisotropic conductive material 11A ... Solder particles 11B ... Thermosetting component

Claims (12)

An anisotropic conductive material used for anisotropic conductive connection,
Including a thermosetting component, a plurality of solder particles having solder on a conductive outer surface, and a flux;
The solder particles are surface-treated with dicarboxylic acid,
An anisotropic conductive material having a difference between the second acid dissociation constant pKa2 of the dicarboxylic acid and the first acid dissociation constant pKa1 of the flux: pKa2−pKa1 is 0.5 or more.   2. The anisotropic conductive material according to claim 1, wherein the content of the solder particles is 10% by weight or more and 90% by weight or less.   The anisotropic conductive material according to claim 2, wherein the content of the solder particles is 10 wt% or more and 60 wt% or less.   The anisotropic conductive material according to claim 1, wherein the solder particles are an anionic polymer or a surface-treated product made of an anionic polymer.   5. The anisotropic conductive material according to claim 1, wherein the anisotropic conductive material has a property that the flux collects on an outer surface of the solder particles when heated to 110 ° C. 6.   The anisotropic conductive material according to claim 1, wherein the solder particles have an average particle diameter of 1 μm or more and 60 μm or less.   The anisotropic conductive material according to claim 1, which is an anisotropic conductive paste. A first connection target member having at least one first electrode on its surface;
A second connection target member having at least one second electrode on its surface;
A connecting portion connecting the first connection target member and the second connection target member;
The material of the connection portion is the anisotropic conductive material according to any one of claims 1 to 7,
A connection structure in which the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.   The connection structure according to claim 8, wherein the second connection target member is a semiconductor chip, a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. Using the anisotropic conductive material according to claim 1, the anisotropic conductive material is formed on a surface of a first connection target member having at least one first electrode on the surface. A step of arranging
On the surface opposite to the first connection target member side of the anisotropic conductive material, a second connection target member having at least one second electrode on the surface, the first electrode and the first Arranging the two electrodes so as to face each other;
The first connection object member and the second connection object member are connected by heating the anisotropic conductive material to a temperature equal to or higher than the melting point of the solder particles and equal to or higher than the curing temperature of the thermosetting component. A connection structure including a step of forming a connection portion from the anisotropic conductive material and electrically connecting the first electrode and the second electrode by a solder portion in the connection portion. Body manufacturing method. In the step of arranging the second connection target member and the step of forming the connection portion, pressure is not applied and the weight of the second connection target member is added to the anisotropic conductive material, or ,
In at least one of the step of arranging the second connection target member and the step of forming the connection portion, pressurizing and forming the second connection target member and the connection portion are formed. The manufacturing method of the connection structure according to claim 10, wherein the pressure of pressurization is less than 1 MPa in both of the steps to be performed.   The manufacturing method of the connection structure of Claim 10 or 11 whose said 2nd connection object member is a semiconductor chip, a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate.

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