JP2018046004A - Conductive material and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive material that makes it possible to efficiently dispose solder in conductive particles between electrodes to be connected, and to improve storage stability.SOLUTION: A conductive material has a binder resin, and a plurality of conductive particles having solder on the external surface of a conductive part, with the conductive particles having a surface flow potential of -1000 mV or more and 0 mV or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive material including conductive particles having solder. The present invention also relates to a connection structure using the conductive material.

  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.

  The anisotropic conductive material is used to obtain various connection structures. Examples of the connection structure include a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), and a semiconductor chip and a glass substrate. (COG (Chip on Glass)), connection between a flexible printed circuit board and a glass epoxy board (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, Patent Document 1 described below describes an anisotropic conductive material including conductive particles and a resin component that cannot be cured at the melting point of the conductive particles. Specifically, as the conductive particles, tin (Sn), indium (In), bismuth (Bi), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), gallium (Ga) ), Silver (Ag), thallium (Tl) and other metals, and alloys of these metals.

  In Patent Document 1, a resin heating step for heating the anisotropic conductive material to a temperature higher than the melting point of the conductive particles and at which the curing of the resin component is not completed, and a resin component curing step for curing the resin component The electrical connection between the electrodes is described. Patent Document 1 describes that mounting is performed with the temperature profile shown in FIG. In Patent Document 1, conductive particles melt in a resin component that is not completely cured at a temperature at which the anisotropic conductive material is heated.

  Patent Document 2 below discloses an adhesive tape that includes a resin layer containing a thermosetting resin, solder powder, and a curing agent, and the solder powder and the curing agent are present in the resin layer. Yes. This adhesive tape is in the form of a film, not a paste.

  The following Patent Document 3 discloses a conductive paste containing a thermosetting component and a plurality of solder particles. The zeta potential on the surface of the solder particles is positive. Patent Document 3 describes solder particles having a positive zeta potential and solder particles having a zeta potential of −25 mV and −27 mV in Examples and Comparative Examples.

JP 2004-260131 A WO2008 / 023452A1 WO2015 / 125778A1

  In the conventional conductive materials as described in Patent Documents 1 and 2, the moving speed of the conductive particles or solder powder onto the electrodes (lines) is slow, and the conductive particles or solder powder is between the upper and lower electrodes to be connected. May not be efficiently arranged.

  In addition, the conventional conductive paste as described in Patent Document 3 may have low storage stability. As a result, the viscosity of the conductive paste increases with time, and the applicability of the conductive paste may vary.

  An object of the present invention is to provide a conductive material that can efficiently dispose solder in conductive particles between electrodes to be connected and can improve storage stability. Another object of the present invention is to provide a connection structure using the conductive material.

  According to a wide aspect of the present invention, the binder resin and a plurality of conductive particles having solder on the outer surface portion of the conductive portion, the flow potential of the surface of the conductive particles is −1000 mV or more and 0 mV or less. A conductive material is provided.

  In a specific aspect of the conductive material according to the present invention, the viscosity at 25 ° C when stored for 24 hours at 25 ° C and 50% humidity is 25 ° C when stored for 0.5 hours at 25 ° C and 50% humidity. The ratio with respect to the viscosity is 1.0 or more and 3.0 or less.

  In a specific aspect of the conductive material according to the present invention, the binder resin includes a thermosetting compound having a polyether skeleton.

  In a specific aspect of the conductive material according to the present invention, a flux having a melting point of 80 ° C. or higher and 140 ° C. or lower is included.

  In a specific aspect of the conductive material according to the present invention, the conductive particles are solder particles.

  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 A connection portion connecting the second connection target member and the second connection target member, wherein the material of the connection portion is the conductive material described above, and the first electrode and the second electrode Is provided that is electrically connected by a solder part in the connection part.

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

  The conductive material according to the present invention includes a binder resin and a plurality of conductive particles having solder on the outer surface portion of the conductive portion, and the flow potential of the surface of the conductive particles is −1000 mV or more and 0 mV or less. Therefore, the solder in the conductive particles can be efficiently disposed between the electrodes to be connected, and the storage stability can be improved.

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained using a 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 a conductive material according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing a modification of the connection structure. FIG. 4 is a cross-sectional view showing a first example of conductive particles that can be used as a conductive material. FIG. 5 is a cross-sectional view showing a second example of conductive particles that can be used for the conductive material. FIG. 6 is a cross-sectional view showing a third example of conductive particles that can be used for the conductive material.

  Details of the present invention will be described below.

(Conductive material)
The conductive material according to the present invention includes a binder resin and a plurality of conductive particles. In the conductive material according to the present invention, the flow potential on the surface of the conductive particles is −1000 mV or more and 0 mV or less. The conductive particles have a conductive part. The conductive particles have solder on the outer surface portion of the conductive portion. The solder is included in the conductive part and is a part or all of the conductive part.

  In this invention, since said structure is provided, the solder in electroconductive particle can be arrange | positioned efficiently between the electrodes which should be connected, and storage stability can be improved. In a conventional conductive material, when the electrode width or the inter-electrode width is narrow, there is a tendency that the solder in the conductive particles is difficult to gather on the electrodes. In the present invention, even if the electrode width or the inter-electrode width is narrow, the solder in the conductive particles can be sufficiently gathered on the electrodes. In the present invention, since the above configuration is provided, when the electrodes are electrically connected, the solder in the conductive particles is easily located between the upper and lower electrodes, and the solder in the conductive particles is used as the electrode. (Line) can be arranged efficiently. In the present invention, when the electrode width is wide, the solder in the conductive particles is arranged more efficiently on the electrode.

  Further, in the case of obtaining a connection structure, when the conductive material is disposed on the first connection target member by screen printing or the like, the viscosity of the conductive material is unlikely to increase, so that the conductive material can be uniformly applied. . Moreover, the laminated body of the first connection target member and the conductive material may be stored for a certain period before the second connection target member is disposed on the conductive material. In this invention, even if the said laminated body is stored, since the viscosity raise of an electrically-conductive material can be suppressed, the connection structure excellent in conduction | electrical_connection reliability can be obtained.

  In order to obtain the effects as described above, the fact that the streaming potential of the surface of the conductive particles is −1000 mV or more and 0 mV or less greatly contributes.

  In the present invention, it is difficult for a part of the solder in the conductive particles to be disposed in a region (space) where no electrode is formed, and the amount of solder disposed in a region where no electrode is formed is considerably reduced. Can do. In the present invention, the solder that is not located between the opposing electrodes can be efficiently moved between the opposing electrodes. 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.

  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 having the conductive material disposed on the upper surface, the electrode of the first connection target member and the electrode of the second connection target member Even in a state where the alignment is shifted, the shift can be corrected and the electrode of the first connection target member and the electrode of the second connection target member can be connected (self-alignment effect).

  From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode, the conductive material is preferably liquid at 25 ° C., and preferably a conductive paste.

  From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode, the viscosity (η25) at 25 ° C. of the conductive material is preferably 50 Pa · s or more, more preferably 80 Pa · s or more. , Preferably 300 Pa · s or less, more preferably 200 Pa · s or less. The said viscosity ((eta) 25) can be suitably adjusted with the kind and compounding quantity of a compounding component.

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

  Viscosity (η1) at 25 ° C. when stored for 24 hours at 25 ° C. and 50% humidity of the above conductive material (η1) when stored for 0.5 hour at 25 ° C. and 50% humidity The ratio (η2 / η1) to is preferably 1.0 or more, preferably 3.0 or less, more preferably 2.0 or less. When the ratio (η2 / η1) is not less than the above lower limit and not more than the above upper limit, the solder in the conductive particles can be more efficiently disposed on the electrode, and the storage stability of the conductive material is further improved. be able to. When the conductive material is frozen, it is preferable to measure η1 and η2 after thawing the conductive material by leaving it at 25 ° C. and 50% humidity for 1 hour.

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

  Hereinafter, each component contained in the conductive material will be described.

(Conductive particles)
The conductive particles electrically connect the electrodes of the connection target member. The conductive particles have solder on the outer surface portion of the conductive portion. The conductive particles may be solder particles. The solder particles have solder on the outer surface portion of the conductive portion. As for the said solder particle, both the center part and the outer surface part of an electroconductive part are formed with the solder. The solder particles are particles in which both the central portion of the solder particles and the outer surface portion of the conductive portion are solder. The said electroconductive particle may have a base material particle and the electroconductive part arrange | positioned on the surface of this base material particle. In this case, the conductive particles have solder on the outer surface portion of the conductive portion.

  Compared to the case where the above solder particles are used, in the case where conductive particles including base particles not formed by solder and solder portions arranged on the surface of the base particles are used, It becomes difficult for conductive particles to gather. In addition, in the conductive particles including the base particles that are not formed by the solder and the solder portions arranged on the surface of the base particles, the conductive particles move to the electrodes because the solder bonding property between the conductive particles is low. The conductive particles tend to move out of the electrodes, and the effect of suppressing displacement between the electrodes tends to be low. Therefore, the conductive particles are preferably solder particles formed by solder.

  From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, a carboxyl group or an amino group is present on the outer surface of the conductive particles (the outer surface of the solder). It is preferable that a carboxyl group is present, and an amino group is preferably present. A group containing a carboxyl group or an amino group is shared on the outer surface of the conductive particle (the outer surface of the solder) via a Si-O bond, an ether bond, an ester bond, or a group represented by the following formula (X). Bonding is preferred. The group containing a carboxyl group or an amino group may contain both a carboxyl group and an amino group. In the following formula (X), the right end and the left end represent a binding site.

  Hydroxyl groups exist on the surface of the solder. By covalently bonding this hydroxyl group and a group containing a carboxyl group, a stronger bond can be formed than in the case of bonding by other coordination bond (chelate coordination) or the like, so the connection resistance between the electrodes is reduced, And the electroconductive particle which can suppress generation | occurrence | production of a void is obtained.

  In the conductive particles, the bond form between the surface of the solder and the group containing a carboxyl group may not include a coordination bond, and may not include a bond due to a chelate coordination.

  The conductive particles react with a hydroxyl group on the surface of the solder using a compound having a functional group capable of reacting with a hydroxyl group and a carboxyl group or an amino group (hereinafter sometimes referred to as compound X). It is preferably obtained by reacting possible functional groups. The conductive particles obtained by the above preferred method can effectively reduce the connection resistance in the connection structure, and can effectively suppress the generation of voids. In the above reaction, a covalent bond is formed. By reacting a hydroxyl group on the surface of the solder with a functional group capable of reacting with the hydroxyl group in the compound X, conductive particles in which a group containing a carboxyl group or an amino group is covalently bonded to the surface of the solder are easily obtained. be able to. In addition, by reacting a hydroxyl group on the surface of the solder with a functional group capable of reacting with the hydroxyl group in the compound X, a group containing a carboxyl group or an amino group is covalently bonded to the surface of the solder via an ether bond or an ester bond. Conductive particles can also be obtained. By reacting a hydroxyl group on the surface of the solder with a functional group capable of reacting with the hydroxyl group, the compound X can be chemically bonded to the surface of the solder in the form of a covalent bond.

  Examples of the functional group capable of reacting with the hydroxyl group include a hydroxyl group, a carboxyl group, an ester group, and a carbonyl group. A hydroxyl group or a carboxyl group is preferred. The functional group capable of reacting with the hydroxyl group may be a hydroxyl group or a carboxyl group.

  Examples of the compound having a functional group capable of reacting with a hydroxyl group include levulinic acid, glutaric acid, glycolic acid, succinic acid, malic acid, oxalic acid, malonic acid, adipic acid, 5-ketohexanoic acid, 3-hydroxypropionic acid, 4- Aminobutyric acid, 3-mercaptopropionic acid, 3-mercaptoisobutyric acid, 3-methylthiopropionic acid, 3-phenylpropionic acid, 3-phenylisobutyric acid, 4-phenylbutyric acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentadecanoic acid, Hexadecanoic acid, 9-hexadecenoic acid, heptadecanoic acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, (9,12,15) -linolenic acid, nonadecanoic acid, arachidic acid, decanedioic acid and dodecanedioic acid It is done. Glutaric acid or glycolic acid is preferred. Only 1 type may be used for the compound which has the functional group which can react with the said hydroxyl group, and 2 or more types may be used together. The compound having a functional group capable of reacting with the hydroxyl group is preferably a compound having at least one carboxyl group.

  The compound X preferably has a flux action, and the compound X preferably has a flux action in a state of being bonded to the solder surface. The compound having a flux action can remove the oxide film on the surface of the solder and the oxide film on the surface of the electrode. The carboxyl group has a flux action.

  Examples of the compound having a flux action include levulinic acid, glutaric acid, glycolic acid, succinic acid, 5-ketohexanoic acid, 3-hydroxypropionic acid, 4-aminobutyric acid, 3-mercaptopropionic acid, 3-mercaptoisobutyric acid, 3- Examples include methylthiopropionic acid, 3-phenylpropionic acid, 3-phenylisobutyric acid, and 4-phenylbutyric acid. Glutaric acid or glycolic acid is preferred. As for the compound which has the said flux effect | action, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, the functional group capable of reacting with the hydroxyl group in the compound X is preferably a hydroxyl group or a carboxyl group. The functional group capable of reacting with the hydroxyl group in the compound X may be a hydroxyl group or a carboxyl group. When the functional group capable of reacting with the hydroxyl group is a carboxyl group, the compound X preferably has at least two carboxyl groups. By reacting a part of the carboxyl group of the compound having at least two carboxyl groups with the hydroxyl group on the surface of the solder, conductive particles in which the group containing the carboxyl group is covalently bonded to the surface of the solder can be obtained.

  The manufacturing method of the said electroconductive particle is equipped with the process of mixing the compound, catalyst, and solvent which have the functional group and carboxyl group which can react with this electroconductive particle and a hydroxyl group, for example using electroconductive particle. In the method for producing conductive particles, conductive particles in which a group containing a carboxyl group is covalently bonded to the surface of the solder can be easily obtained by the mixing step.

  Moreover, in the said manufacturing method of electroconductive particle, using electroconductive particle, this electroconductive particle, the compound which has the functional group and carboxyl group which can react with the said hydroxyl group, the said catalyst, and the said solvent are mixed, and it heats. It is preferable. By the mixing and heating step, conductive particles in which a group containing a carboxyl group is covalently bonded to the surface of the solder can be obtained more easily.

  Examples of the solvent include methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, ethyl acetate, toluene, and xylene. The solvent is preferably an organic solvent, and more preferably toluene. As for the said solvent, only 1 type may be used and 2 or more types may be used together.

  Examples of the catalyst include p-toluenesulfonic acid, benzenesulfonic acid and 10-camphorsulfonic acid. The catalyst is preferably p-toluenesulfonic acid. As for the said catalyst, only 1 type may be used and 2 or more types may be used together.

  It is preferable to heat at the time of the mixing. The heating temperature is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, preferably 130 ° C. or lower, more preferably 110 ° C. or lower.

  From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, the conductive particles react with the isocyanate compound to the hydroxyl group on the surface of the solder using the isocyanate compound. It is preferable that it is obtained through the process of making it. In the above reaction, a covalent bond is formed. By reacting the hydroxyl group on the surface of the solder with the isocyanate compound, it is possible to easily obtain conductive particles in which the nitrogen atom of the group derived from the isocyanate group is covalently bonded to the surface of the solder. By reacting the isocyanate compound with a hydroxyl group on the surface of the solder, a group derived from an isocyanate group can be chemically bonded to the surface of the solder in the form of a covalent bond.

  Moreover, a silane coupling agent can be easily reacted with a group derived from an isocyanate group. Since the said electroconductive particle can be obtained easily, it is preferable that the group containing the said carboxyl group is introduce | transduced by reaction using the silane coupling agent which has a carboxyl group. Moreover, since the said electroconductive particle can be obtained easily, the group containing the said carboxyl group has at least 1 carboxyl group in the group derived from a silane coupling agent after reaction using a silane coupling agent. It is preferably introduced by reacting a compound. The conductive particles are preferably obtained by reacting the isocyanate compound with a hydroxyl group on the surface of the solder using the isocyanate compound and then reacting a compound having at least one carboxyl group.

  From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, the compound having at least one carboxyl group preferably has a plurality of carboxyl groups.

  Examples of the isocyanate compound include diphenylmethane-4,4'-diisocyanate (MDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), and isophorone diisocyanate (IPDI). Isocyanate compounds other than these may be used. After reacting this compound on the surface of the solder, by reacting the residual isocyanate group and a compound having reactivity with the residual isocyanate group and having a carboxyl group, the surface of the solder is represented by the above formula (X). A carboxyl group can be introduced through the group represented.

  As said isocyanate compound, you may use the compound which has an unsaturated double bond and has an isocyanate group. Examples include 2-acryloyloxyethyl isocyanate and 2-isocyanatoethyl methacrylate. After reacting the isocyanate group of this compound on the surface of the solder, reacting the compound having a functional group having reactivity with the remaining unsaturated double bond and having a carboxyl group, A carboxyl group can be introduced to the surface via a group represented by the above formula (X).

  Examples of the silane coupling agent include 3-isocyanatopropyltriethoxysilane (“KBE-9007” manufactured by Shin-Etsu Silicone), 3-isocyanatepropyltrimethoxysilane (“Y-5187” manufactured by MOMENTIVE), and the like. As for the said silane coupling agent, only 1 type may be used and 2 or more types may be used together.

  Examples of the compound having at least one carboxyl group include levulinic acid, glutaric acid, glycolic acid, succinic acid, malic acid, oxalic acid, malonic acid, adipic acid, 5-ketohexanoic acid, 3-hydroxypropionic acid, 4-amino Butyric acid, 3-mercaptopropionic acid, 3-mercaptoisobutyric acid, 3-methylthiopropionic acid, 3-phenylpropionic acid, 3-phenylisobutyric acid, 4-phenylbutyric acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecane Examples include acid, 9-hexadecenoic acid, heptadecanoic acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, (9,12,15) -linolenic acid, nonadecanoic acid, arachidic acid, decanedioic acid, and dodecanedioic acid. . Glutaric acid, adipic acid or glycolic acid is preferred. As for the compound which has at least 1 said carboxyl group, only 1 type may be used and 2 or more types may be used together.

  After reacting the isocyanate compound with the hydroxyl group on the surface of the solder using the isocyanate compound, the carboxyl group of the compound having a plurality of carboxyl groups is reacted with the hydroxyl group on the surface of the solder. The group containing can be left.

  In the method for producing conductive particles, the conductive particles are used and the isocyanate compound is used to react the hydroxyl group on the surface of the solder with the isocyanate compound, and then the compound having at least one carboxyl group is reacted. Thus, conductive particles in which a group containing a carboxyl group is bonded to the surface of the solder via the group represented by the above formula (X) are obtained. In the method for producing conductive particles, conductive particles in which a group containing a carboxyl group is introduced on the surface of the solder can be easily obtained by the above-described steps.

  The following method is mentioned as a specific manufacturing method of the said electroconductive particle. Conductive particles are dispersed in an organic solvent, and a silane coupling agent having an isocyanate group is added. Thereafter, a silane coupling agent is covalently bonded to the surface of the solder using a reaction catalyst between a hydroxyl group and an isocyanate group on the surface of the solder of the conductive particles. Next, a hydroxyl group is produced | generated by hydrolyzing the alkoxy group couple | bonded with the silicon atom of a silane coupling agent. The produced hydroxyl group is reacted with a carboxyl group of a compound having at least one carboxyl group.

  Moreover, the following method is mentioned as a specific manufacturing method of the said electroconductive particle. Conductive particles are dispersed in an organic solvent, and a compound having an isocyanate group and an unsaturated double bond is added. Thereafter, a covalent bond is formed using a reaction catalyst of a hydroxyl group and an isocyanate group on the surface of the solder of the conductive particles. Thereafter, the unsaturated double bond introduced is reacted with a compound having an unsaturated double bond and a carboxyl group.

  The reaction catalyst for hydroxyl groups and isocyanate groups on the surface of the solder of the conductive particles includes tin catalysts (dibutyltin dilaurate, etc.), amine catalysts (triethylenediamine, etc.), carboxylate catalysts (lead naphthenate, potassium acetate, etc.) And a trialkylphosphine catalyst (such as triethylphosphine).

  From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, the compound having at least one carboxyl group is a compound represented by the following formula (1): Is preferred. The compound represented by the following formula (1) has a flux action. Moreover, the compound represented by following formula (1) has a flux effect | action in the state introduced into the surface of solder.

  In said formula (1), X represents the functional group which can react with a hydroxyl group, R represents a C1-C5 bivalent organic group. The organic group may contain a carbon atom, a hydrogen atom, and an oxygen atom. The organic group may be a divalent hydrocarbon group having 1 to 5 carbon atoms. The main chain of the organic group is preferably a divalent hydrocarbon group. In the organic group, a carboxyl group or a hydroxyl group may be bonded to a divalent hydrocarbon group. Examples of the compound represented by the above formula (1) include citric acid.

  The compound having at least one carboxyl group is preferably a compound represented by the following formula (1A) or the following formula (1B). The compound having at least one carboxyl group is preferably a compound represented by the following formula (1A), and more preferably a compound represented by the following formula (1B).

  In said formula (1A), R represents a C1-C5 bivalent organic group. R in the above formula (1A) is the same as R in the above formula (1).

  In said formula (1B), R represents a C1-C5 bivalent organic group. R in the above formula (1B) is the same as R in the above formula (1).

  A group represented by the following formula (2A) or the following formula (2B) is preferably bonded to the surface of the solder. A group represented by the following formula (2A) is preferably bonded to the surface of the solder, and more preferably a group represented by the following formula (2B) is bonded. In the following formula (2A) and the following formula (2B), the left end portion represents a binding site.

  In said formula (2A), R represents a C1-C5 bivalent organic group. R in the above formula (2A) is the same as R in the above formula (1).

  In said formula (2B), R represents a C1-C5 bivalent organic group. R in the above formula (2B) is the same as R in the above formula (1).

  From the viewpoint of enhancing the wettability of the solder surface, the molecular weight of the compound having at least one carboxyl group is preferably 10,000 or less, more preferably 1000 or less, and even more preferably 500 or less.

  The molecular weight means a molecular weight that can be calculated from the structural formula when the compound having at least one carboxyl group is not a polymer and when the structural formula of the compound having at least one carboxyl group can be specified. Further, when the compound having at least one carboxyl group is a polymer, it means a weight average molecular weight.

  From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode, and from the viewpoint of further improving the storage stability of the conductive material, the conductive particles include a conductive particle body, a hydrophobic compound layer, and the like. And an acid compound layer. The hydrophobic compound layer is preferably disposed on the surface of the conductive particle body, and the acid compound layer is preferably disposed on the surface of the hydrophobic compound layer.

  From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode, the acid compound layer is preferably formed of a compound having a carboxyl group. The acid compound in the acid compound layer is preferably a compound having a carboxyl group. Examples of the compound having a carboxyl group include glutaric acid and adipic acid. The conductive particles preferably have a conductive particle body, a hydrophobic compound layer, and a compound having a carboxyl group disposed on the surface of the hydrophobic compound layer. The conductive particles are preferably obtained by surface-treating the hydrophobic compound layer with a compound having a carboxyl group. The conductive particles are preferably a surface-treated product with a compound having a carboxyl group. As for the compound which has the said carboxyl group, only 1 type may be used and 2 or more types may be used together.

  Examples of the method for surface-treating the hydrophobic compound layer with a compound having a carboxyl group include dehydration condensation.

  In the conductive material according to the present invention, the flow potential on the surface of the conductive particles is −1000 mV or more and 0 mV or less. From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode and further improving the storage stability of the conductive material, the flow potential of the conductive particles is preferably −700 mV or more, more Preferably it is -600 mV or more, preferably -200 mV or less, more preferably -300 mV or less.

  The streaming potential is measured as follows.

  Conductive particles are recovered by dissolving the conductive material in acetone. 1 g of the obtained conductive particles are dispersed in 90 g of water and 10 g of acetone. The streaming potential of this dispersion is measured using a streaming potential measuring device (“Stabino PMX 400” manufactured by Microtrack Bell). The measurement time is set to 60 seconds, and the gap between the cell and the piston is set to 400 μm.

  Examples of the method for adjusting the streaming potential within a suitable range include a method for adjusting the amount of a compound having a carboxyl group or a phosphoric acid compound disposed on the surface of the conductive particles. As a method for adjusting the amount of the compound having a carboxyl group, the phosphoric acid compound, etc., the conductive particles are measured while measuring the streaming potential of the conductive particles surface-treated with the compound having a carboxyl group or the phosphoric acid compound. The method etc. which wash | clean this with hexane or acetone are mentioned.

  Next, specific examples of conductive particles will be described with reference to the drawings.

  FIG. 4 is a cross-sectional view showing a first example of conductive particles that can be used as a conductive material.

  The conductive particles 21 shown in FIG. 4 are solder particles. The conductive particles 21 are entirely formed of solder. The conductive particles 21 do not have base particles in the core, and are not core-shell particles. As for the electroconductive particle 21, both the center part and the outer surface part of an electroconductive part are formed with the solder.

  FIG. 5 is a cross-sectional view showing a second example of conductive particles that can be used for the conductive material.

  The conductive particle 31 shown in FIG. 5 includes a base particle 32 and a conductive part 33 disposed on the surface of the base particle 32. The conductive portion 33 covers the surface of the base particle 32. The conductive particles 31 are coated particles in which the surface of the base particle 32 is covered with the conductive portion 33.

  The conductive portion 33 includes a second conductive portion 33A and a solder portion 33B (first conductive portion). The conductive particle 31 includes a second conductive portion 33A between the base particle 32 and the solder portion 33B. Therefore, the conductive particles 31 are composed of the base particle 32, the second conductive portion 33A disposed on the surface of the base particle 32, and the solder portion 33B disposed on the outer surface of the second conductive portion 33A. With.

  FIG. 6 is a cross-sectional view showing a third example of conductive particles that can be used for the conductive material.

  As described above, the conductive portion 33 in the conductive particle 31 has a two-layer structure. The conductive particle 41 shown in FIG. 6 has a solder part 42 as a single-layer conductive part. The conductive particles 41 include base particles 32 and solder portions 42 disposed on the surfaces of the base particles 32.

  Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles excluding metal, and are preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The substrate particles may be copper particles. The base particle may have a core and a shell disposed on the surface of the core, or may be a core-shell particle. The core may be an organic core, and the shell may be an inorganic shell.

  Various organic materials are suitably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, polyether agent Ketone, polyether sulfone, divinyl benzene polymer, and divinylbenzene copolymer, and the like. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid ester copolymer. Since the hardness of the resin particles can be easily controlled within a suitable range, the resin for forming the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. It is preferably a coalescence.

  When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer and And a crosslinkable monomer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, Alkyl (meth) acrylate compounds such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, and glycidyl (meth) Oxygen atom-containing (meth) acrylate compounds such as acrylate; Nitrile-containing monomers such as (meth) acrylonitrile; Vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; Vinyl acetate, vinyl butyrate, vinyl laurate, and stearin Acid vinyl ester compounds such as vinyl acid; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene And halogen-containing monomers such as

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylate compounds such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, and 1,4-butanediol di (meth) acrylate; triallyl (iso) silane Silane-containing monomers such as nurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, and γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane Examples include the body.

  The term “(meth) acrylate” refers to acrylate and methacrylate. The term “(meth) acryl” refers to acrylic and methacrylic. The term “(meth) acryloyl” refers to acryloyl and methacryloyl.

  The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

  In the case where the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal, examples of the inorganic material for forming the substrate particles include silica, alumina, barium titanate, zirconia, and carbon black. The inorganic substance is preferably not a metal. The particles formed from the silica are not particularly limited. For example, after forming a crosslinked polymer particle by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups, firing may be performed as necessary. The particle | grains obtained by performing are mentioned. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. From the viewpoint of effectively reducing the connection resistance between the electrodes, the base material particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

  Examples of the material for forming the organic core include the resin for forming the resin particles described above.

  Examples of the material for forming the inorganic shell include inorganic substances for forming the above-described base material particles. The material for forming the inorganic shell is preferably silica. The inorganic shell is preferably formed on the surface of the core by forming a metal alkoxide into a shell by a sol-gel method and then sintering the shell. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed of a silane alkoxide.

  The particle diameter of the core is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 50 μm or less, further preferably 40 μm or less, particularly preferably 30 μm or less, and most preferably 15 μm or less. It is. When the particle diameter of the core is not less than the above lower limit and not more than the above upper limit, conductive particles more suitable for electrical connection between electrodes can be obtained, and the base particles can be suitably used for the use of conductive particles. Become. For example, when the particle diameter of the core is not less than the lower limit and not more than the upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, and When the conductive portion is formed on the surface of the base particle, it is difficult to form aggregated conductive particles. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive portion is difficult to peel from the surface of the base particle.

  The particle diameter of the core means the diameter when the core is a true sphere, and the maximum diameter when the core is a shape other than the true sphere. Moreover, the particle diameter of a core means the average particle diameter which measured the core with arbitrary particle diameter measuring apparatuses. For example, a particle size distribution measuring machine using principles such as laser light scattering, electrical resistance value change, and image analysis after imaging can be used.

  The thickness of the shell is preferably 100 nm or more, more preferably 200 nm or more, preferably 5 μm or less, more preferably 3 μm or less. When the thickness of the shell is not less than the above lower limit and not more than the above upper limit, conductive particles more suitable for electrical connection between the electrodes can be obtained, and the base particles can be suitably used for the use of conductive particles. . The thickness of the shell is an average thickness per base particle. The thickness of the shell can be controlled by controlling the sol-gel method.

  When the substrate particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium. When the base material particles are metal particles, the metal particles are preferably copper particles. However, the substrate particles are preferably not metal particles.

  The particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 1 μm or more, further preferably 1.5 μm or more, and particularly preferably 2 μm or more. The particle diameter of the substrate particles is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 40 μm or less, still more preferably 20 μm or less, still more preferably 10 μm or less, particularly preferably 5 μm or less, and most preferably 3 μm. It is as follows. When the particle diameter of the base material particles is equal to or larger than the lower limit, the contact area between the conductive particles and the electrodes is increased, so that the conduction reliability between the electrodes can be further improved and the connection is made through the conductive particles. The connection resistance between the formed electrodes can be further reduced. When the particle diameter of the substrate particles is not more than the above upper limit, the conductive particles are easily compressed, the connection resistance between the electrodes can be further reduced, and the interval between the electrodes can be further reduced. it can.

  The particle diameter of the base particle indicates a diameter when the base particle is a true sphere, and indicates a maximum diameter when the base particle is not a true sphere.

  The particle diameter of the substrate particles is particularly preferably 2 μm or more and 5 μm or less. When the particle diameter of the substrate particles is in the range of 2 μm or more and 5 μm or less, the distance between the electrodes can be further reduced, and even if the thickness of the conductive layer is increased, small conductive particles can be obtained. Can do.

  The method for forming the conductive part on the surface of the base particle and the method for forming the solder part on the surface of the base particle or the surface of the second conductive part are not particularly limited. Examples of the method for forming the conductive portion and the solder portion include a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, And a method of coating the surface of the substrate particles with a paste containing metal powder or metal powder and a binder. Electroless plating, electroplating or physical collision methods are preferred. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method based on the physical collision, for example, a sheeter composer (manufactured by Tokuju Kogakusha Co., Ltd.) or the like is used.

  The melting point of the substrate particles is preferably higher than the melting points of the conductive part and the solder part. The melting point of the substrate particles is preferably higher than 160 ° C, more preferably higher than 300 ° C, still more preferably higher than 400 ° C, and particularly preferably higher than 450 ° C. The melting point of the substrate particles may be less than 400 ° C. The melting point of the substrate particles may be 160 ° C. or less. The softening point of the substrate particles is preferably 260 ° C. or higher. The softening point of the substrate particles may be less than 260 ° C.

  The conductive particles may have a single layer solder portion. The conductive particles may have a plurality of layers of conductive parts (solder part, second conductive part). That is, in the conductive particles, two or more conductive portions may be stacked. When the conductive part has two or more layers, the conductive particles preferably have solder on the outer surface portion of the conductive part.

  The solder is preferably a metal (low melting point metal) having a melting point of 450 ° C. or lower. The solder part is preferably a metal layer (low melting point metal layer) having a melting point of 450 ° C. or lower. The low melting point metal layer is a layer containing a low melting point metal. The solder in the conductive particles is preferably metal particles having a melting point of 450 ° C. or lower (low melting point metal particles). The low melting point metal particles are particles containing a low melting point metal. The low melting point metal 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 in the conductive particles preferably contains tin. In 100% by weight of the metal contained in the solder part and 100% by weight of the metal contained in the solder in the conductive particles, the content of tin is preferably 30% by weight or more, more preferably 40% by weight or more, and still more preferably. Is 70% by weight or more, particularly preferably 90% by weight or more. When the content of tin contained in the solder in the conductive particles is not less than the above lower limit, the conduction reliability between the conductive particles 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 conductive particles having the solder on the outer surface portion of the conductive portion, the solder is melted and joined to the electrodes, and the solder conducts between the electrodes. For example, since the solder and the electrode are not in point contact but in surface contact, the connection resistance is lowered. In addition, the use of conductive particles having solder on the outer surface of the conductive portion increases the bonding strength between the solder and the electrode, and as a result, the solder and the electrode are more unlikely to peel off, and the conduction reliability is effective. To be high.

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

  In order to further increase the bonding strength between the solder and the electrode, the solder in the conductive particles is nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese. Further, it may contain a metal such as chromium, molybdenum and palladium. Moreover, from the viewpoint of further increasing the bonding strength between the solder and the electrode, the solder in the conductive particles preferably contains nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further increasing the bonding strength between the solder and the electrode in the solder portion or the conductive particles, the content of these metals for increasing the bonding strength is preferably 0% in 100% by weight of the solder in the conductive particles. 0.0001% by weight or more, preferably 1% by weight or less.

  The melting point of the second conductive part is preferably higher than the melting point of the solder part. The melting point of the second conductive part is preferably more than 160 ° C, more preferably more than 300 ° C, still more preferably more than 400 ° C, still more preferably more than 450 ° C, particularly preferably more than 500 ° C, Most preferably above 600 ° C. Since the solder part has a low melting point, it melts during conductive connection. It is preferable that the second conductive portion does not melt during conductive connection. The conductive particles are preferably used by melting solder, preferably used by melting the solder part, and used without melting the solder part and melting the second conductive part. It is preferred that Since the melting point of the second conductive part is higher than the melting point of the solder part, only the solder part can be melted without melting the second conductive part at the time of conductive connection.

  The absolute value of the difference between the melting point of the solder part and the melting point of the second conductive part exceeds 0 ° C, preferably 5 ° C or more, more preferably 10 ° C or more, still more preferably 30 ° C or more, particularly preferably 50 ° C. or higher, most preferably 100 ° C. or higher.

  The second conductive part preferably contains a metal. The metal which comprises the said 2nd electroconductive part is not specifically limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and alloys thereof. Further, tin-doped indium oxide (ITO) may be used as the metal. As for the said metal, only 1 type may be used and 2 or more types may be used together.

  The second conductive part is preferably a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably a nickel layer or a gold layer, and even more preferably a copper layer. The conductive particles preferably have a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably have a nickel layer or a gold layer, and more preferably have a copper layer. By using the conductive particles having these preferable conductive parts for the connection between the electrodes, the connection resistance between the electrodes is further reduced. Moreover, a solder part can be more easily formed on the surface of these preferable conductive parts.

  The thickness of the solder part is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 0.3 μm or less. When the thickness of the solder part is not less than the above lower limit and not more than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed when connecting the electrodes. .

  The average particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, preferably 100 μm or less, more preferably 50 μm or less, still more preferably 40 μm or less, particularly preferably. Is 30 μm or less. When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the solder in the conductive particles can be arranged more efficiently on the electrodes, and there are many solders in the conductive particles between the electrodes. It is easy to arrange and the conduction reliability is further enhanced.

  The average particle diameter of the conductive particles indicates a number average particle diameter. The average particle diameter of the conductive particles is obtained, for example, by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  The variation coefficient of the particle diameter of the conductive 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 in the conductive particles can be more efficiently arranged on the electrode. However, the coefficient of variation of the particle diameter of the conductive 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 conductive particles Dn: Average value of particle diameter of conductive particles

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

  The content of the conductive 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. Is 30% by weight or more, preferably 80% by weight or less, more preferably 60% by weight or less, and still more preferably 50% by weight or less. When the content of the conductive particles is not less than the above lower limit and not more than the above upper limit, the solder in the conductive particles can be arranged more efficiently on the electrodes, and more solder in the conductive particles is arranged between the electrodes. It is easy to do and the conduction reliability is further increased. From the viewpoint of further improving the conduction reliability, the content of the conductive particles is preferably large.

(Binder resin)
The binder resin is not particularly limited. A known insulating resin can be used as the binder resin.

  Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. As for the said binder resin, only 1 type may be used and 2 or more types may be used together.

  Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. Examples of the curable resin include an epoxy resin, a urethane resin, a polyimide resin, and an unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated product of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogenated product of a styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

  The conductive material and the binder resin preferably contain a thermoplastic component or a thermosetting component. The conductive material and the binder resin may contain a thermoplastic component or may contain a thermosetting component. The conductive material and the binder resin preferably contain a thermosetting component. The thermosetting component preferably contains a thermosetting compound curable by heating and a thermosetting agent.

(Thermosetting component: thermosetting compound)
The thermosetting compound is a compound that can be cured by heating. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, 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 or an episulfide compound is preferable. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode, the thermosetting compound preferably includes a thermosetting compound having a polyether skeleton.

  Examples of the thermosetting compound having a polyether skeleton include a compound having a glycidyl ether group at both ends of an alkyl chain having 3 to 12 carbon atoms, and a polyether skeleton having 2 to 4 carbon atoms. Examples thereof include polyether type epoxy compounds having structural units in which 2 to 10 are bonded continuously.

  From the viewpoint of further increasing the heat resistance of the cured material of the conductive material and further reducing the dielectric constant of the cured material of the conductive material, the thermosetting compound includes a thermosetting compound having a triazine skeleton. Is preferred.

  Examples of the thermosetting compound having a triazine skeleton include triazine triglycidyl ether, and the like. PAS, TEPIC-VL, TEPIC-UC) and the like.

  An aromatic epoxy compound is mentioned as said epoxy compound. Crystalline epoxy compounds such as resorcinol type epoxy compounds, naphthalene type epoxy compounds, biphenyl type epoxy compounds, and benzophenone type epoxy compounds are preferred. An epoxy compound that is solid at normal temperature (23 ° C.) and has a melting temperature equal to or lower than the melting point of the solder is preferable. The melting temperature is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and preferably 40 ° C. or higher. By using the preferable epoxy compound, the first connection target member and the second connection target are high when the connection target member is bonded to each other when the viscosity is high and acceleration is applied by impact such as conveyance. The positional deviation with respect to the member can be suppressed. Furthermore, by using the above-mentioned preferable epoxy compound, the viscosity of the conductive material can be greatly reduced by the heat at the time of curing, and the aggregation of the solder can be efficiently advanced.

  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. More preferably, it is 98 weight% or less, More preferably, it is 90 weight% or less, Most preferably, it is 80 weight% or less. When the content of the thermosetting compound is not less than the above lower limit and not more than the above upper limit, the solder in the conductive particles is more efficiently arranged on the electrodes, and the displacement between the electrodes is further suppressed, and the electrodes The conduction reliability between them can be further enhanced. From the viewpoint of further improving the impact resistance, it is preferable that the content of the thermosetting compound is large.

(Thermosetting component: thermosetting agent)
The thermosetting agent thermosets the thermosetting compound. Examples of the thermosetting agent include an imidazole curing agent, a phenol curing agent, a thiol curing agent, an amine curing agent, an acid anhydride curing agent, a thermal cation curing agent, and a thermal radical generator. As for the said thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of allowing the conductive material to be cured more rapidly at a low temperature, the thermosetting agent is preferably an imidazole curing agent, a thiol curing agent, or an amine curing agent. Further, from the viewpoint of enhancing the storage stability when the thermosetting compound and the thermosetting agent are mixed, the thermosetting agent is preferably a latent curing agent. The latent curing agent is preferably a latent imidazole curing agent, a latent thiol curing agent, or a latent amine curing agent. 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. Examples of the imidazole curing agent include 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-triazine isocyanuric acid adducts Etc.

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

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

  Examples of the thermal cationic curing agent include iodonium-based cationic curing agents, oxonium-based cationic curing agents, and sulfonium-based cationic 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. Examples of the thermal radical generator 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, further preferably 80 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, and further preferably 150 ° C. Hereinafter, it is particularly preferably 140 ° C. or lower. 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 in the conductive particles is 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 conductive particles, more preferably 5 ° C or higher, More preferably, it is 10 ° C. or higher.

  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 with respect to 100 parts by weight of the thermosetting compound 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 or less, more preferably 75 parts by weight or less. It is easy to fully harden a thermosetting compound as content of a thermosetting agent is more than the said minimum. 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 the flux, the solder in the conductive particles can be arranged more efficiently 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 or pine resin having two or more carboxyl groups. 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.

  The melting point (activation temperature) of the flux is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, further preferably 80 ° C. or higher, preferably 220 ° C. or lower, more preferably 190 ° C. or lower, and still more preferably 160 ° C or lower, more preferably 150 ° C or lower, and still more preferably 140 ° C or lower. When the melting point 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 in the conductive particles is more efficiently disposed on the electrode. The melting point (activation temperature) of the flux is preferably 80 ° C. or higher and 190 ° C. or lower. The melting point (activation temperature) of the flux is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

  Examples of the flux having a melting point (activation temperature) 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.), dicarboxylic acids such as suberic acid (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), malic acid (melting point 130 ° C.) and the like.

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

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

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

  The said flux may be disperse | distributed in the electrically-conductive material and may adhere on the surface of electroconductive particle.

  When the melting point of the flux is higher than the melting point of the solder, the solder 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 in the conductive particles is exceeded, the solder in the conductive 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 part first reaches the melting point (activation temperature) of the flux, the oxide film on the surface of the solder on the conductive particles preferentially coming on the electrode is removed or activated. Since the electric charge on the surface of the solder in the conductive particles is neutralized by the flux, the solder can spread on the surface of the electrode. Thereby, a solder can be efficiently aggregated on an 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, more preferably 25% by weight or less. The conductive material may not contain flux. When the content of the flux is not less than the above lower limit and not more than the above upper limit, it becomes more difficult to form an oxide film on the surface of the solder and the electrode, and further, the oxide film formed on the surface of the solder and the electrode is more effective. Can be removed.

(Insulating particles)
From the viewpoint of controlling the interval between the connection target members connected by the cured material of the conductive material with high accuracy and from the viewpoint of controlling the interval between the connection target members connected by the solder in the conductive particles with high accuracy, The conductive material preferably contains insulating particles. In the conductive material, the insulating particles may not be attached to the surface of the conductive particles. In the conductive material, the insulating particles are preferably present apart from the conductive particles.

  The average particle diameter of the insulating particles is preferably 10 μm or more, more preferably 20 μm or more, further preferably 25 μm or more, preferably 100 μm or less, more preferably 75 μm or less, and further preferably 50 μm or less. When the average particle diameter of the insulating particles is not less than the above lower limit and not more than the above upper limit, the interval between the connection target members connected by the cured material of the conductive material, and the connection target member connected by the solder in the conductive particles The interval between them becomes even more reasonable.

  Examples of the material of the insulating particles include an insulating resin and an insulating inorganic substance. As said insulating resin, the said resin etc. which were mentioned as resin for forming the resin particle which can be used as a base particle are mentioned. As said insulating inorganic substance, the said inorganic substance etc. which were mentioned as an inorganic substance for forming the inorganic particle which can be used as a base particle are mentioned.

  Specific examples of the insulating resin that is the material of the insulating particles include polyolefin compounds, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, heat Examples thereof include curable resins and water-soluble resins.

  Examples of the polyolefin compound include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate. Examples of the block polymer include polystyrene, styrene-acrylic acid ester copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. As said thermosetting resin, an epoxy resin, a phenol resin, a melamine resin, etc. are mentioned. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, polyethylene oxide, and methyl cellulose. A water-soluble resin is preferable, and polyvinyl alcohol is more preferable.

  Specific examples of the insulating inorganic material that is the material of the insulating particles include silica and organic-inorganic hybrid particles. The particles formed from the silica are not particularly limited. For example, after forming a crosslinked polymer particle by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups, firing may be performed as necessary. The particle | grains obtained by performing are mentioned. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  The content of the insulating particles in 100% by weight of the conductive material is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, preferably 10% by weight or less, more preferably 5% by weight. % Or less. The conductive material may not contain insulating particles. When the content of the insulating particles is not less than the above lower limit and not more than the above upper limit, the interval between the connection target members connected by the cured material of the conductive material, and between the connection target members connected by the solder in the conductive particles The interval becomes even more reasonable.

  The conductive material may be, for example, a coupling agent, a light-shielding agent, a reactive diluent, an antifoaming agent, a leveling agent, a filler, an extender, a softening agent, a plasticizer, a polymerization catalyst, a curing catalyst, or a coloring agent. Various additives such as an agent, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, 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 material of the connection portion is the conductive material described above. The connecting portion is a cured product of the conductive material described above. The connecting portion is formed of the 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 said connection structure is equipped with the process of arrange | positioning the said electrically-conductive material on the surface of the 1st connection object member which has an at least 1 1st electrode on the surface using the electrically conductive material mentioned above. In the method for manufacturing the connection structure, the second connection target member having at least one second electrode on the surface of the conductive material opposite to the first connection target member side is provided on the surface. A step of disposing the first electrode and the second electrode so as to face each other. In the method for manufacturing the connection structure, the first connection target member and the second connection target member are connected by heating the conductive material to a temperature equal to or higher than the melting point of the solder in the conductive particles. Forming a portion with the conductive material and electrically connecting the first electrode and the second electrode with a solder portion in the connection portion. Preferably, the conductive material is heated above the curing temperature of the thermosetting component (thermosetting compound).

  In the connection structure according to the present invention and the method for manufacturing the connection structure, since a specific conductive material is used, solder in a plurality of conductive particles easily collects between the first electrode and the second electrode. The solder can be efficiently arranged on the electrode (line). In addition, a part of the solder is difficult to be disposed in a region (space) where no electrode is formed, and the amount of solder 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.

  Further, in order to efficiently arrange the solder in the plurality of conductive particles on the electrode and to considerably reduce the amount of the solder arranged in the region where the electrode is not formed, the conductive material is made of a conductive film. It is preferable to use a conductive paste.

  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 70% or more, and 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 preferably added. In the method for manufacturing the connection structure, in the step of arranging the second connection target member and the step of forming the connection portion, the conductive material is subjected to a process that 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 made even more effective, and a large amount of solder in a plurality of conductive particles tends to gather between the electrodes, and the solder in the plurality of conductive particles is more efficiently distributed on the electrode (line). Can be arranged. In addition, it is difficult for a part of the solder in the plurality of conductive particles to be disposed in the region (space) where the electrode is not formed, and the amount of solder in the conductive particle disposed in the region where the electrode is not formed is further increased. Can be 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.

  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. Moreover, in the conductive film, compared with the conductive paste, the melt viscosity of the conductive film cannot be sufficiently lowered at the melting temperature of the solder, and the aggregation of the solder 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 a 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 the conductive material described above. In the present embodiment, the conductive material includes conductive particles and a binder resin. In the present embodiment, the conductive material includes solder particles as conductive particles. In this embodiment, binder resin contains a thermosetting compound and a thermosetting agent. The thermosetting compound and the thermosetting agent are referred to as 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.

  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 solder particles, the solder portion 4A, the first electrode 2a, and the solder as compared with the case where the outer surface portion of the conductive portion is made of conductive particles such as nickel, gold or copper are used. The contact area between the portion 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.

  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.

  In connection structure 1, 1X, when the part which 1st electrode 2a and 2nd electrode 3a oppose in the lamination direction of 1st electrode 2a, connection part 4, 4X, and 2nd electrode 3a is seen In addition, it is preferable that the solder portions 4A and 4XA in the connection portions 4 and 4X are arranged in 50% or more of the area of 100% of the facing portion between the first electrode 2a and the second electrode 3a. . Satisfaction of the above preferred embodiment can further enhance the conduction reliability.

  When 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, the first electrode and the second electrode It is preferable that the solder portion in the connecting portion is arranged in 50% or more of the area of 100% of the portion facing the two electrodes. When 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, the first electrode and the second electrode It is more preferable that the solder portion in the connection portion is disposed in 60% or more of 100% of the area of the portion facing the two electrodes. When 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, the first electrode and the second electrode More preferably, the solder portion in the connecting portion is arranged in 70% or more of the area of 100% of the portion facing the two electrodes. When 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, the first electrode and the second electrode It is particularly preferable that the solder portion in the connecting portion is disposed in 80% or more of 100% of the area facing the two electrodes. When 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, the first electrode and the second electrode It is most preferable that the solder portion in the connection portion is disposed in 90% or more of the area of 100% of the portion facing the two electrodes. Satisfaction of the above preferred embodiment can further enhance the conduction reliability.

  When the portion where the first electrode and the second electrode face each other in the direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode is seen, It is preferable that 60% or more of the solder portion in the connection portion is disposed in a portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other in the direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode is seen, More preferably, 70% or more of the solder portion in the connection portion is disposed in a portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other in the direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode is seen, More preferably, 90% or more of the solder portion in the connection portion is disposed in a portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other in the direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode is seen, It is particularly preferable that 95% or more of the solder portion in the connection portion is disposed at a portion where the electrode and the second electrode face each other. When the portion where the first electrode and the second electrode face each other in the direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode is seen, It is most preferable that 99% or more of the solder portion in the connection portion is disposed in a portion where the electrode and the second electrode face each other. Satisfaction of the above preferred embodiment can further enhance the conduction reliability.

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

  First, the 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 including a thermosetting component 11B and a plurality of solder particles 11A is disposed on the surface of the first connection target member 2 (first Process). The used conductive material 11 contains a thermosetting compound and a thermosetting agent as the thermosetting component 11B.

  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 arrangement method of the conductive material 11 is not particularly limited, and examples thereof include application using a dispenser, screen printing, and ejection using an inkjet apparatus.

  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 (third step). Preferably, the conductive material 11 is heated above the curing temperature of the thermosetting component 11B (thermosetting compound). At the time of this heating, the solder particles 11A that existed in the region where no electrode is formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). When the conductive paste is used instead of the conductive film, the solder particles 11A are effectively collected between the first electrode 2a and the second electrode 3a. 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, it is preferable that no pressure is applied in the second step and the third step. In this case, the weight of the second connection target member 3 is added to the conductive material 11. 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 solder particles 11A tend to collect between the first electrode 2a and the second electrode 3a. The tendency to be inhibited becomes high.

  In the present embodiment, since no pressure is applied, when the second connection target member is superimposed on the first connection target member coated with the conductive material, the first electrode and the second electrode are overlapped. Even in a state where the alignment is shifted, the shift can be corrected and the first electrode and the second electrode can be connected (self-alignment effect). This is because the molten solder self-aggregated between the first electrode and the second electrode is in contact with the solder between the first electrode and the second electrode and the other components of the conductive material. This is because the area having the smallest area is more stable in terms of energy, and therefore the force to make the connection structure with alignment, which is the connection structure having the smallest area, works. At this time, it is desirable that the conductive material is not cured, and that the viscosity of components other than the conductive particles of the conductive material is sufficiently low at that temperature and time.

  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 preferably 140 ° C. or higher, more preferably 160 ° C. or higher, preferably 450 ° C. or lower, more preferably 250 ° C. or lower, and even more preferably 200 ° C. or lower.

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

  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 thereof include electronic components such as circuit boards such as flat cables, rigid flexible boards, glass epoxy boards, and glass boards. The first and second connection target members are preferably electronic components.

  It is preferable that at least one of the first connection target member and the second connection target member is a resin film, a flexible printed 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 not to gather on an electrode. On the other hand, by using a conductive paste, even if a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board is used, the conductive reliability between the electrodes can be efficiently collected by collecting the solder on the electrodes. Can be increased sufficiently. 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.

  Examples of the electrode provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, a SUS electrode, and a tungsten electrode. 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.

Thermosetting compound 1: Epoxy compound, “EP-3300” manufactured by ADEKA, epoxy equivalent 160 g / eq
Thermosetting compound 2: Epoxy compound, “TEPIC-SS” manufactured by Nissan Chemical Co., Ltd.
Latent epoxy thermosetting agent 1: “Fujicure 7000” manufactured by T & K TOKA
Latent epoxy thermosetting agent 2: “HXA3922-HP” manufactured by Asahi Kasei E-materials
Latent epoxy thermosetting agent 3: “TMTP-E” manufactured by Sakai Chemical Co., Ltd.
flux:
25 parts by weight of glutaric acid and 25 parts by weight of monomethyl glutarate were placed in a three-necked flask and dissolved at 80 ° C. under a nitrogen flow. Thereafter, 57 parts by weight of benzylamine was added and reacted at 80 ° C. under reduced pressure (4 Torr or less) for 2 hours to obtain a flux that was solid at 25 ° C.

  Insulating particles: average particle size 30 μm, CV value 5%, softening point 330 ° C., Sekisui Chemical Co., Ltd., divinylbenzene crosslinked particles

Production of conductive particles 1:
200 g of conductive particle bodies (solder particles), 40 g of a silane coupling agent, and 0.5 g of butyltin dilaurate as a catalyst were weighed and reacted at 100 ° C. for 2 hours. Next, 120 g of methanol was added and reacted at 60 ° C. for 1 hour. Thereafter, the conductive particles were collected by filtration and washed with methanol.

  Next, the entire amount of the collected conductive particles was put in 150 g of water and reacted for 30 minutes. Thereafter, the conductive particles were collected by vacuum filtration.

  Next, the total amount of the collected conductive particles, 30 g of monoethyl adipate, 0.2 g of dimethylammonium pentafluorobenzenesulfonate as a dehydration condensation catalyst, and 30 g of acetone were weighed and reacted at 60 ° C. for 45 minutes. . Next, 0.2 g of lanthanum isopropoxide, 30 g of glutaric acid, and 90 g of acetone were added as a transesterification catalyst and reacted at 60 ° C. for 1 hour. Thereafter, the conductive particles were collected by filtration, and the conductive particles were washed with a mixed solvent of 150 g of acetone and 150 g of hexane.

  The streaming potential of the surface of the obtained conductive particles 1 was −420 mV.

Production of conductive particles 2:
Conductive particles 2 were obtained in the same manner as the conductive particles 1 except that a mixed solvent of 90 g of acetone and 210 g of hexane was used when washing the conductive particles.

  The streaming potential on the surface of the obtained conductive particles 2 was −250 mV.

Production of conductive particles 3:
Conductive particles 3 were obtained in the same manner as the conductive particles 1 except that a mixed solvent of 210 g of acetone and 90 g of hexane was used when washing the conductive particles.

  The flow potential on the surface of the obtained conductive particles 3 was −620 mV.

Production of conductive particles 4:
Conductive particles 4 were obtained in the same manner as the conductive particles 1 except that a mixed solvent of 30 g of acetone and 270 g of hexane was used when washing the conductive particles.

  The streaming potential on the surface of the obtained conductive particles 4 was -170 mV.

Production of conductive particles 5:
Conductive particles 5 were obtained in the same manner as the conductive particles 1 except that a mixed solvent of 270 g of acetone and 30 g of hexane was used when washing the conductive particles.

  The flow potential on the surface of the obtained conductive particles 5 was −750 mV.

Production of conductive particles 6:
In the production of the conductive particles 1, the reaction with the silane coupling agent, water, monoethyl adipate, and glutaric acid was not performed, and the conductive particle main body was used as the conductive particles 6.

  The flow potential on the surface of the obtained conductive particles 6 was −900 mV.

Production of conductive particles 7:
In the production of the conductive particles 1, the reaction with monoethyl adipate and glutaric acid was not carried out, but only the reaction with the silane coupling agent and water was carried out to collect the conductive particles. The collected conductive particles were used as the conductive particles 7.

  The flow potential on the surface of the obtained conductive particles 7 was −1100 mV.

Production of conductive particles 8:
200 g of conductive particle bodies (solder particles), 40 g of adipic acid, 70 g of acetone, and 0.3 g of dibutyltin oxide as a catalyst were weighed and reacted at 60 ° C. for 4 hours. Then, it collect | recovered by filtering electroconductive particle.

  The total amount of the collected conductive particles, 50 g of adipic acid, 200 g of toluene, and 0.3 g of paratoluenesulfone sun were weighed and reacted at 120 ° C. for 3 hours. Thereafter, the conductive particles were collected by filtration and washed with hexane.

  The flow potential on the surface of the obtained conductive particles 8 was 10 mV.

(Flow potential on the surface of conductive particles)
The streaming potential on the surface of the conductive particles was measured as follows.

  1 g of the obtained conductive particles was dispersed in 90 g of water and 10 g of acetone. The streaming potential of this dispersion was measured using a streaming potential measuring device (“Stabino PMX 400” manufactured by Microtrack Bell). The measurement time was set to 60 seconds, and the gap between the cell and the piston was set to 400 μm.

(Examples 1-6 and Comparative Examples 1 and 2)
(1) Production of conductive material The components shown in Table 1 below were blended in the blending amounts shown in Table 1 to obtain a conductive material (anisotropic conductive paste).

(2) Production of Connection Structure A glass epoxy substrate (first electrode) having a gold electrode pattern (gold electrode thickness 10 μm) having an L / S of 100 μm / 100 μm and an electrode length of 4 mm on the upper surface was prepared. Moreover, the flexible printed circuit board (2nd electrode) which has a gold electrode pattern with L / S of 100 micrometers / 100 micrometers on the lower surface was prepared.

  The overlapping area of the glass epoxy substrate and the flexible printed board was 1.5 cm × 4 mm, and the number of connected electrodes was 72 pairs.

  On the upper surface of the glass epoxy substrate, the anisotropic conductive paste immediately after preparation was applied to a thickness of 120 μm to form an anisotropic conductive paste layer. 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, the solder was melted while heating so that the temperature of the anisotropic conductive paste layer was 150 ° C., and the anisotropic conductive paste layer was cured at 150 ° C. to obtain a connection structure.

(Evaluation)
(1) Viscosity ratio (η2 / η1)
The viscosity (η1) at 25 ° C. when the conductive material immediately after production was stored at 25 ° C. and 50% humidity for 0.5 hours was measured. Further, the conductive material immediately after the production was stored at 25 ° C. and a humidity of 50%. Thereafter, the viscosity (η2) at 25 ° C. of the conductive material when stored at 25 ° C. and 50% humidity for 24 hours was measured. The viscosity was measured under the conditions of 25 ° C. and 5 rpm using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.). The viscosity ratio (η2 / η1) was calculated from the measured viscosity value.

(2) Solder placement accuracy on the electrode In the obtained connection structure, a portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the solder portion, and the second electrode The ratio X of the area where the solder portion is disposed 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%

(3) Conduction reliability between upper and lower electrodes In the obtained connection structure (n = 15), the connection resistance per connection portion between the upper and lower electrodes was measured by a four-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. However, when even one of n = 15 was not conductive between the upper and lower electrodes, it was determined as “x”.

[Judgment criteria for conduction reliability]
◯: Average value of connection resistance is 6.5Ω or less ○: Average value of connection resistance exceeds 6.5Ω, 6.8Ω or less △: Average value of connection resistance exceeds 6.8Ω, 7.2Ω or less × : The average value of connection resistance exceeds 7.2Ω, or connection failure occurs.

(4) Insulation reliability between electrodes adjacent in the horizontal direction In the obtained connection structure (n = 15), after leaving in an atmosphere of 85 ° C. and 85% humidity for 100 hours, between the electrodes adjacent in the horizontal direction Then, 15V was applied, and the resistance value was measured at 25 locations. Insulation reliability was judged according to the following criteria. However, when even one of n = 15 electrodes is electrically connected in the horizontal direction, it was determined as “x”.

[Criteria for insulation reliability]
◯: Average connection resistance is 10 ⁶ Ω or more ○: Average connection resistance is 10 ⁵ Ω or more, less than 10 ⁶ Ω △: Average connection resistance is 10 ⁴ Ω or more, less than 10 ⁵ Ω ×: Connection The average resistance is less than 10 ⁴ Ω

  The results are shown in Table 1 below.

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 ... Conductive material 11A ... Solder particles (conductive particles)
11B ... thermosetting component 21 ... conductive particles (solder particles)
31 ... Conductive particles 32 ... Base particle 33 ... Conductive part (conductive part having solder)
33A ... second conductive part 33B ... solder part 41 ... conductive particles 42 ... solder part

Claims (7)

Including a binder resin and a plurality of conductive particles having solder on the outer surface portion of the conductive portion;
A conductive material having a surface flow potential of the conductive particles of −1000 mV or more and 0 mV or less.   The ratio of the viscosity at 25 ° C. when stored at 25 ° C. and 50% humidity for 24 hours to the viscosity at 25 ° C. when stored at 25 ° C. and 50% humidity for 0.5 hours is 1.0 or more, 3 The conductive material according to claim 1, which is 0.0 or less.   The conductive material according to claim 1, wherein the binder resin contains a thermosetting compound having a polyether skeleton.   The conductive material according to claim 1, comprising a flux having a melting point of 80 ° C. or higher and 140 ° C. or lower.   The conductive material according to claim 1, wherein the conductive particles are solder particles. 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 connection portion connecting the first connection target member and the second connection target member;
The material of the connection part is the conductive material according to any one of claims 1 to 5,
A connection structure in which the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.   When the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode 7. The connection structure according to claim 6, wherein a solder portion in the connection portion is arranged in 50% or more of an area of 100% of a portion facing the two electrodes.

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