JP6630284B2 - Conductive material and connection structure - Google Patents

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 films are widely known. In the anisotropic conductive material, conductive particles are dispersed in a binder.

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

  For example, when electrically connecting an electrode of a flexible printed circuit board and an electrode of a glass epoxy board by the anisotropic conductive material, an anisotropic conductive material containing conductive particles is arranged on the glass epoxy board. I do. Next, the flexible printed circuit boards are laminated and heated and pressed. Thereby, 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 Literature 1 described below describes an anisotropic conductive material including conductive particles and a resin component whose curing is not completed at the melting point of the conductive particles. Specific examples of the conductive particles include tin (Sn), indium (In), bismuth (Bi), silver (Ag), copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd). ), Gallium (Ga) and thallium (Tl), and alloys of these metals.

  In Patent Document 1, a resin heating step of heating an anisotropic conductive resin 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 of curing the resin component And that the electrodes are electrically connected. Further, Patent Document 1 describes that mounting is performed with a temperature profile shown in FIG. 8 of Patent Document 1. In Patent Literature 1, the conductive particles are melted in a resin component whose curing is not completed at a temperature at which the anisotropic conductive resin is heated.

  Patent Document 2 listed below discloses an adhesive tape including a resin layer containing a thermosetting resin, a solder powder, and a curing agent, wherein the solder powder and the curing agent are present in the resin layer. I have. This adhesive tape is in the form of a film, not a paste.

JP-A-2004-260131 WO2008 / 023452A1

  The present inventors have found that in a conventional solder powder or an anisotropic conductive material containing conductive particles having a solder layer on the surface, the cured product of the anisotropic conductive material contains black soot derived from solder. I found that there is. In particular, when the solder is subjected to a flux action by the flux, black soot is easily generated. This black soot increases the connection resistance between the electrodes and lowers the conduction reliability.

  Further, when the electrodes are electrically connected by the method described in Patent Document 1 using the anisotropic conductive material described in Patent Document 1, conductive particles including solder are efficiently placed on the electrodes (lines). May not be placed. Further, in the example of Patent Document 1, at a temperature equal to or higher than the melting point of the solder, the solder is kept at a constant temperature in order to sufficiently move the solder, and the manufacturing efficiency of the connection structure is reduced. When mounting is performed with the temperature profile shown in FIG. 8 of Patent Document 1, the manufacturing efficiency of the connection structure decreases.

  Further, the adhesive tape described in Patent Document 2 is in the form of a film, not a paste. With an adhesive tape having a composition as described in Patent Document 2, it is difficult to efficiently arrange solder powder on electrodes (lines). For example, in the adhesive tape described in Patent Literature 2, a part of the solder powder is likely to be arranged in a region (space) where no electrode is formed. The solder powder arranged in the region where no electrode is formed does not contribute to conduction between the electrodes.

  An object of the present invention is to provide a conductive material that can suppress the occurrence of black soot in a cured product, can further selectively arrange solder in conductive particles on electrodes, and can improve conduction reliability. It is. 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, on the outer surface portion of a conductive portion, a plurality of conductive particles having solder, a thermosetting component, and a flux, as the thermosetting component or the flux, an isocyanuric skeleton And a viscosity of the conductive material at the melting point of the solder in the conductive particles is 0.1 Pa · s or more and 20 Pa · s or less.

  The weight ratio of the content of the compound having the isocyanuric skeleton to the content of the flux is preferably 0.5 or more and 20 or less. The weight ratio of the content of the compound having an isocyanuric skeleton to the content of the conductive particles is preferably 0.05 or more and 0.5 or less.

  In a specific aspect of the conductive material according to the present invention, the compound having an isocyanuric skeleton has a molecular weight of 200 to 1,000.

  In a specific aspect of the conductive material according to the present invention, the conductive material includes, as the thermosetting component, a thermosetting compound having an isocyanuric skeleton or a thermosetting agent having an isocyanuric skeleton.

  In a specific aspect of the conductive material according to the present invention, the conductive material includes a thermosetting compound having an isocyanuric skeleton as the thermosetting component.

  In one specific aspect of the conductive material according to the present invention, the conductive material includes, as the thermosetting component, a thermosetting compound having no isocyanuric skeleton.

  In a specific aspect of the conductive material according to the present invention, the thermosetting component includes a thermosetting compound having an isocyanuric skeleton and a thermosetting compound having no isocyanuric skeleton.

  In a specific aspect of the conductive material according to the present invention, the thermosetting compound having no isocyanuric skeleton is a thermosetting compound having no isocyanuric skeleton and having an aromatic skeleton or an alicyclic skeleton. .

  In a specific aspect of the conductive material according to the present invention, the conductive material includes a phosphate compound.

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

  In a specific aspect of the conductive material according to the present invention, the conductive material is a liquid at 25 ° C. and is a conductive paste.

  According to a broad aspect of the present invention, a first connection target member having at least one first electrode on a surface, a second connection target member having at least one second electrode on a surface, And a connection portion connecting the second connection target member and the second connection target member, wherein the connection portion is a cured product of the above-described conductive material, and the first electrode and the second electrode Are 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 a stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the portion, the solder portion in the connection portion is arranged at 50% or more of the area of 100% of the facing portion of the first electrode and the second electrode.

  The conductive material according to the present invention includes, on the outer surface portion of the conductive portion, a plurality of conductive particles having solder, a thermosetting component, and a flux, and as the thermosetting component or the flux, an isocyanuric skeleton. Since the viscosity of the conductive material at the melting point of the solder in the conductive particles is 0.1 Pa · s or more and 20 Pa · s or less in the conductive particles, the occurrence of black soot is suppressed in the cured conductive material. be able to. Further, the solder in the conductive particles can be selectively arranged on the electrode, and the conduction reliability can be improved.

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained using a conductive material according to one embodiment of the present invention. FIGS. 2A to 2C are cross-sectional views illustrating steps 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 sectional view showing a modification of the connection structure. FIG. 4 is a cross-sectional view illustrating a first example of conductive particles that can be used for a conductive material. FIG. 5 is a cross-sectional view illustrating a second example of conductive particles that can be used for a conductive material. FIG. 6 is a cross-sectional view illustrating a third example of conductive particles that can be used for a conductive material.

  Hereinafter, details of the present invention will be described.

(Conductive material)
The conductive material according to the present invention includes a plurality of conductive particles and a binder. The conductive particles have a conductive portion. The conductive particles have solder on the outer surface of the conductive part. The solder is included in the conductive part and is a part or all of the conductive part. The binder is a component excluding the conductive particles contained in the conductive material.

  The conductive material according to the present invention contains a thermosetting component and a flux as the binder. The thermosetting component contains a thermosetting compound. The thermosetting component preferably contains a thermosetting agent.

  The conductive material according to the present invention contains a compound having an isocyanuric skeleton as the thermosetting component or the flux. The compound having an isocyanuric skeleton may be a thermosetting component having an isocyanuric skeleton, a flux having an isocyanuric skeleton, or a thermosetting compound having an isocyanuric skeleton or a thermosetting agent having an isocyanuric skeleton. There may be. The thermosetting component having an isocyanuric skeleton may be a thermosetting compound having an isocyanuric skeleton or a thermosetting agent having an isocyanuric skeleton.

  In the conductive material according to the present invention, the viscosity of the conductive material at the melting point of the solder in the conductive particles is 0.1 Pa · s or more and 20 Pa · s or less.

  In the present invention, since the above configuration is provided, it is possible to suppress the occurrence of black soot derived from solder in the cured product of the conductive material. When black soot is contained in the cured material of the conductive material, the connection resistance between the electrodes is increased, and the conduction reliability is reduced. In the present invention, since the occurrence of black soot can be suppressed, the connection resistance between the electrodes can be reduced, and the conduction reliability can be increased.

  Furthermore, in the present invention, since the above configuration is provided, in particular, since the viscosity at the melting point of the solder in the conductive particles of the conductive material is within the range described above, the solder in the conductive particles on the electrode is preferably used. Can be selectively arranged. When the electrodes are electrically connected, the solder in the conductive particles easily collects between the upper and lower opposed electrodes, and the solder in the conductive particles can be efficiently arranged on the electrodes (lines).

  Further, it is difficult for a part of the solder in the conductive particles to be arranged in the region (space) where the electrode is not formed, and the amount of the solder arranged in the region where the electrode is not formed can be considerably reduced. According to the present invention, the solder that is not located between the facing electrodes can be efficiently moved between the facing electrodes. Therefore, the reliability of conduction between the electrodes can be improved. In addition, electrical connection between horizontally adjacent electrodes that must not be connected can be prevented, and insulation reliability can be improved.

  In order to more efficiently arrange the solder on the electrodes, the conductive material is preferably liquid at 25 ° C., and is preferably a conductive paste.

  In order to arrange the solder efficiently on the electrode, the viscosity (ηmp) of the conductive material at the melting point of the solder in the conductive particles is 0.1 Pa · s or more and 20 Pa · s or less. From the viewpoint of more efficiently disposing the solder on the electrode, the viscosity (ηmp) is preferably 1 Pa · s or more, preferably 15 Pa · s or less, more preferably 10 Pa · s or less. When the viscosity (ηmp) is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles or the solder move efficiently from the initial period to the middle period during the conductive connection.

  The above viscosity can be measured using a strain control (manufactured by EOLOGICA) or the like, with a strain control of 1 rad, a frequency of 1 Hz, a heating rate of 20 ° C./min, and a measurement temperature range of 40 to 200 ° C. (However, when the melting point of the solder exceeds 200 ° C.) The upper limit of the temperature is taken as the melting point of the solder). The melting point of the solder may be 200 ° C. or less.

  The conductive material can be used as a conductive paste and a conductive film. The conductive material is preferably an anisotropic conductive material. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film. The conductive material is suitably used for electrical connection of electrodes. The conductive material is preferably a circuit connecting material.

  From the viewpoint of further suppressing the generation of black soot, the compound having an isocyanuric skeleton has a molecular weight of preferably 200 or more, more preferably 300 or more, preferably 1,000 or less, and more preferably 600 or less.

  From the viewpoint of further suppressing the generation of black soot, the content of the compound having an isocyanuric skeleton in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 10% by weight or more, and more preferably Is at most 30% by weight, more preferably at most 20% by weight.

  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 of the conductive portion. The conductive particles may be solder particles. The solder particles are formed of solder. The solder particles have solder on the outer surface of the conductive part. 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. In the solder particles, both the central portion and the outer surface portion of the conductive portion are formed of solder. The conductive particles may have base particles and a conductive part disposed on the surface of the base particles. In this case, the conductive particles have solder on the outer surface of the conductive part.

  In addition, compared to the case where the above-mentioned solder particles are used, when the conductive particles including the base particles not formed by the solder and the solder portion disposed on the surface of the base particles are used, the electrode Conductive particles are less likely to collect on the surface, and the solderability of the conductive particles is low, so that the conductive particles that have moved onto the electrodes tend to move out of the electrodes, thus suppressing the displacement between the electrodes. Also tend to be lower. Accordingly, the conductive particles are preferably solder particles.

  From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, the presence of a carboxyl group or an amino group on the outer surface of the conductive particles (outer surface of the solder). Is preferable, and a carboxyl group is preferably 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 particles (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). It is preferably bonded, and more preferably a group containing a carboxyl group or an amino group is covalently bonded via an ether bond, an ester bond or a group represented by the following formula (X). 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 are present on the surface of the solder. By covalently bonding the hydroxyl group and the group containing a carboxyl group, a stronger bond can be formed than in the case of bonding by another coordination bond (chelate coordination) or the like. In addition, conductive particles capable of suppressing generation of voids can be obtained.

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

  From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, the conductive particles include a compound having a functional group capable of reacting with a hydroxyl group and a carboxyl group or an amino group ( The compound is preferably obtained by reacting a hydroxyl group on the surface of the solder with a functional group capable of reacting with the hydroxyl group using a compound X). 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 having a group containing a carboxyl group or an amino group covalently bonded to the surface of the solder can be easily obtained. It is also possible to obtain conductive particles having a group containing a carboxyl group or an amino group covalently bonded to the surface of the solder via an ether bond or an ester bond. By reacting the 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.

  Compounds 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, and 4-hydroxypropionic acid. 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, decandioic acid, dodecandioic acid and the like. Can be Glutaric acid or glycolic acid is preferred. As the compound having a functional group capable of reacting with a hydroxyl group, only one kind may be used, or two or more kinds may be used in combination. The compound having a functional group capable of reacting with a 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 surface of the solder. The compound having the flux action can remove the oxide film on the surface of the solder and the oxide film on the surface of the electrode. Carboxyl groups have a flux action.

  Compounds 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, Examples include methylthiopropionic acid, 3-phenylpropionic acid, 3-phenylisobutyric acid, and 4-phenylbutyric acid. Glutaric acid or glycolic acid is preferred. Only one compound having the flux action may be used, or two or more compounds may be used in combination.

  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 some carboxyl groups of the compound having at least two carboxyl groups with hydroxyl groups on the surface of the solder, conductive particles having a group containing a carboxyl group covalently bonded to the surface of the solder can be obtained.

  The method for producing conductive particles includes, for example, a step of using the conductive particles and mixing the conductive particles, a compound having a functional group capable of reacting with a hydroxyl group and a carboxyl group, a catalyst, and a solvent. In the method for producing conductive particles, the mixing step makes it possible to easily obtain conductive particles having a group containing a carboxyl group covalently bonded to the surface of the solder.

  In the method for producing the conductive particles, the conductive particles are used, the conductive particles, the compound having a functional group capable of reacting with a hydroxyl group and a carboxyl group, the catalyst and the solvent are mixed and heated. Is preferred. By the mixing and heating steps, conductive particles having a group containing a carboxyl group covalently bonded to the surface of the solder can be more easily obtained.

  Examples of the solvent include alcohol solvents such as methanol, ethanol, propanol and butanol, acetone, methyl ethyl ketone, ethyl acetate, toluene and xylene. The solvent is preferably an organic solvent, more preferably toluene. One of the above solvents may be used alone, or two or more thereof may be used in combination.

  Examples of the catalyst include p-toluenesulfonic acid, benzenesulfonic acid, and 10-camphorsulfonic acid. The catalyst is preferably p-toluenesulfonic acid. Only one type of the above catalyst may be used, or two or more types may be used in combination.

  It is preferable to heat during the mixing. The heating temperature is preferably at least 90 ° C, more preferably at least 100 ° C, preferably at most 130 ° C, more preferably at most 110 ° C.

  From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, the conductive particles react with the hydroxyl groups on the solder surface using an isocyanate compound. Preferably, it is obtained through a step of causing In the above reaction, a covalent bond is formed. By reacting the hydroxyl group on the surface of the solder with the isocyanate compound, conductive particles having a nitrogen atom of a group derived from the isocyanate group covalently bonded to the surface of the solder can be easily obtained. By reacting the isocyanate compound with the hydroxyl group on the surface of the solder, a group derived from the isocyanate group can be chemically bonded to the surface of the solder in the form of a covalent bond.

  In addition, a silane coupling agent can easily react with a group derived from an isocyanate group. Since the conductive particles can be easily obtained, the group containing a carboxyl group has been introduced by a reaction using a silane coupling agent having a carboxyl group, or a reaction using a silane coupling agent. It is preferably introduced later by reacting a compound having at least one carboxyl group with a group derived from the silane coupling agent. The conductive particles are preferably obtained by reacting the hydroxyl group on the surface of the solder with the isocyanate compound using the isocyanate compound, and then reacting the compound with 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). You may use other isocyanate compounds. After reacting this compound on the surface of the solder, by reacting the remaining isocyanate group with a compound having reactivity with the remaining isocyanate group and having a carboxyl group, the above formula (X) A carboxyl group can be introduced via the represented group.

  As the isocyanate compound, a compound having an unsaturated double bond and having an isocyanate group may be used. Examples include 2-acryloyloxyethyl isocyanate and 2-isocyanatoethyl methacrylate. After reacting the isocyanate group of this compound with the surface of the solder, it has a functional group reactive with the remaining unsaturated double bond, and reacts with a compound having a carboxyl group to form a solder. A carboxyl group can be introduced into 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 Co., Ltd.) and 3-isocyanatopropyltrimethoxysilane (“Y-5187” manufactured by MOMENTIVE). The silane coupling agent may be used alone or in combination of two or more.

  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, and 4-amino acid. 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 Acids, 9-hexadecenoic acid, heptadecanoic acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, (9,12,15) -linolenic acid, nonadecanoic acid, arachidic acid, decandioic acid, dodecandioic acid and the like. . Glutaric acid, adipic acid or glycolic acid is preferred. Only one compound having at least one carboxyl group may be used, or two or more compounds may be used in combination.

  Using the above isocyanate compound, the hydroxyl group on the solder surface is reacted with the isocyanate compound, and then a part of the carboxyl group of the compound having a plurality of carboxyl groups is reacted with the hydroxyl group on the solder surface to obtain a carboxyl group. Can be left.

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

  The following method is mentioned as a specific method for producing the conductive particles. The 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 generated by hydrolyzing the alkoxy group bonded to the silicon atom of the silane coupling agent. The generated hydroxyl group is reacted with a carboxyl group of a compound having at least one carboxyl group.

  Further, a specific method for producing the conductive particles includes the following method. The 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 between a hydroxyl group and an isocyanate group on the surface of the solder of the conductive particles. Thereafter, a compound having an unsaturated double bond and a carboxyl group is reacted with the introduced unsaturated double bond.

  Examples of the catalyst for the reaction between the hydroxyl group and the isocyanate group on the surface of the solder of the conductive particles include a tin catalyst (such as dibutyltin dilaurate), an amine catalyst (such as triethylenediamine), and a carboxylate catalyst (such as lead naphthenate and potassium acetate). 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. Further, the compound represented by the following formula (1) has a flux action when introduced to the surface of the solder.

  In the above formula (1), X represents a functional group capable of reacting with a hydroxyl group, and R represents a divalent organic group having 1 to 5 carbon atoms. The organic group may include 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. The compound represented by the above formula (1) includes, for example, 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 the formula (1A), R represents a divalent organic group having 1 to 5 carbon atoms. R in the above formula (1A) is the same as R in the above formula (1).

  In the above formula (1B), R represents a divalent organic group having 1 to 5 carbon atoms. R in the above formula (1B) is the same as R in the above formula (1).

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

  In the above formula (2A), R represents a divalent organic group having 1 to 5 carbon atoms. R in the above formula (2A) is the same as R in the above formula (1).

  In the above formula (2B), R represents a divalent organic group having 1 to 5 carbon atoms. 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 1,000 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. When the compound having at least one carboxyl group is a polymer, it means the weight average molecular weight.

  Since the cohesiveness of the conductive particles can be effectively increased at the time of conductive connection, the conductive particles may have a conductive particle body and an anionic polymer disposed on the surface of the conductive particle body. preferable. The conductive particles are preferably obtained by subjecting the conductive particle body to a surface treatment with an anionic polymer or a compound that becomes an anionic polymer. The conductive particles are preferably surface-treated with an anionic polymer or a compound to be an anionic polymer. The anion polymer and the compound to be the anion polymer may be used alone or in combination of two or more. The anionic polymer is a polymer having an acidic group.

  As a method of surface-treating the conductive particle body with an anionic polymer, for example, a (meth) acrylic polymer obtained by copolymerizing (meth) acrylic acid, a dicarboxylic acid and a diol, and carboxyl groups at both terminals are used as the anionic polymer. Polyester polymer having a carboxyl group at both terminals obtained by an intermolecular dehydration condensation reaction of a dicarboxylic acid, a polyester polymer synthesized from dicarboxylic acid and a diamine and having a carboxyl group at both terminals, and a modification having a carboxyl group A method in which a carboxyl group of an anionic polymer is reacted with a hydroxyl group on the surface of the conductive particle main body using Poval (“Gosennex T” manufactured by Nippon Synthetic Chemical Co., Ltd.) or the like.

Examples of the anionic portion of the anionic polymer, the carboxyl group and the like, in otherwise, tosyl group _{(p-H 3 CC 6 H} 4 S (= O) 2 -), sulfonate ion group (-SO ₃ ^- ) And a phosphate ion group (—PO ₄ ⁻ ).

  Further, as another method of surface treatment, a compound having a functional group that reacts with a hydroxyl group on the surface of the conductive particle body, and further having a functional group that can be polymerized by addition and condensation reaction, is used to convert the compound. There is a method of polymerizing on the surface of the conductive particle body. Examples of the functional group that reacts with the hydroxyl group on the surface of the conductive particle body include a carboxyl group and an isocyanate group. Examples of the functional group polymerized by addition and condensation reactions include a hydroxyl group, a carboxyl group, an amino group, and ) Acryloyl groups.

  The weight average molecular weight of the anionic polymer is preferably 2,000 or more, more preferably 3,000 or more, preferably 10,000 or less, more preferably 8,000 or less. When the weight average molecular weight is equal to or greater than the lower limit and equal to or less than the upper limit, a sufficient amount of charge and flux can be introduced to the surface of the conductive particles. Thereby, the cohesiveness of the conductive particles can be effectively increased at the time of conductive connection, and the oxide film on the surface of the electrode can be effectively removed at the time of connection of the connection target member.

  When the weight average molecular weight is equal to or greater than the lower limit and equal to or less than the upper limit, it is easy to arrange an anionic polymer on the surface of the conductive particle main body, and it is possible to effectively increase the cohesiveness of the solder particles during conductive connection. As a result, the conductive particles can be more efficiently arranged on the electrode.

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

  The weight average molecular weight of the anionic polymer is determined by dissolving the solder in the conductive particles and removing the conductive particles by dilute hydrochloric acid or the like that does not cause decomposition of the anionic polymer, and then measuring the weight average molecular weight of the remaining anionic polymer. Can be obtained by:

  Regarding the amount of the anionic polymer introduced on the surface of the conductive particles, the acid value per 1 g of the conductive particles is preferably 1 mgKOH or more, more preferably 2 mgKOH or more, preferably 10 mgKOH or less, more preferably 6 mgKOH or less.

  The acid value can be measured as follows. 1 g of the conductive particles is added to 36 g of acetone, and dispersed for 1 minute by ultrasonic waves. Thereafter, phenolphthalein is used as an indicator, and titration is performed with a 0.1 mol / L potassium hydroxide ethanol solution.

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

  FIG. 4 is a cross-sectional view illustrating a first example of conductive particles that can be used for 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 the base particles in the core and are not core-shell particles. In the conductive particles 21, both the central part and the outer surface part of the conductive part are formed by solder.

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

  The conductive particles 31 shown in FIG. 5 include base particles 32 and a conductive part 33 arranged on the surface of the base particles 32. The conductive part 33 covers the surface of the base particles 32. The conductive particles 31 are coated particles in which the surfaces of the base particles 32 are coated with the conductive portions 33.

  The conductive part 33 has a second conductive part 33A and a solder part 33B (first conductive part). The conductive particles 31 include a second conductive portion 33A between the base particles 32 and the solder portion 33B. Therefore, the conductive particles 31 include the base particles 32, the second conductive portion 33A disposed on the surface of the base particles 32, and the solder portion 33B disposed on the outer surface of the second conductive portion 33A. And

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

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

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

  Various organic substances 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; and 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, polyetherether Tons, polyether sulfone, divinyl benzene polymer, and divinylbenzene copolymer, and the like. Examples of the divinylbenzene-based copolymer include a divinylbenzene-styrene copolymer and a divinylbenzene- (meth) acrylate copolymer. Since the hardness of the resin particles can be easily controlled to 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 preferred that they are united.

  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 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, cyclohexyl ( Alkyl (meth) acrylate compounds such as meth) acrylate and isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, and glycidyl (meth) acrylate (Meth) acrylate compounds containing nitrogen atoms; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether; acids such as vinyl acetate, vinyl butyrate, vinyl laurate and vinyl stearate Vinyl ester compounds; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene And the like.

  Examples of the crosslinkable monomer include tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, trimethylolpropanetri (meth) acrylate, and dipentane. 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) cyanu Silane-containing monomers such as carboxylate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, and γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane Body and the like.

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

  When the base particles are inorganic particles other than metals or organic-inorganic hybrid particles, examples of the inorganic substance for forming the base particles include silica, alumina, barium titanate, zirconia, and carbon black. It is preferable that the inorganic substance is not a metal. The particles formed of the silica are not particularly limited. For example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, baking is optionally performed. Particles obtained by performing the method are mentioned. Examples of the organic-inorganic hybrid particles include, for example, organic-inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

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

  The particle diameter of the base particles is preferably 0.1 μm or more, more preferably 1 μm or more, further preferably 1.5 μm or more, particularly preferably 2 μm or more, preferably 100 μm or less, more preferably 50 μm or less, more preferably It is more preferably at most 40 μm, more preferably at most 20 μm, still more preferably at most 10 μm, particularly preferably at most 5 μm, most preferably at most 3 μm. When the particle diameter of the base 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 reliability of conduction between the electrodes can be further improved, and the connection via the conductive particles is performed. The connection resistance between the electrodes can be further reduced. When the particle diameter of the base particles is equal to or less than the upper limit, the conductive particles are easily sufficiently compressed, the connection resistance between the electrodes can be further reduced, and the distance between the electrodes can be further reduced. it can.

  The particle diameter of the base particles indicates a diameter when the base particles are truly spherical, and indicates a maximum diameter when the base particles are not true spherical.

  It is particularly preferable that the particle diameter of the base particles is 2 μm or more and 5 μm or less. When the particle diameter of the base particles is in the range of 2 μm or more and 5 μm or less, the distance between the electrodes can be reduced, and even if the thickness of the conductive portion is increased, small conductive particles can be obtained. Can be.

  The method for forming the conductive portion on the surface of the base particle, and the method for forming the solder portion on the surface of the base particle or the surface of the second conductive portion are not particularly limited. As a method of forming the conductive portion and the solder portion, for example, 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 base particles with a metal powder or a paste containing the metal powder and a binder. Electroless plating, electroplating or a method based on physical collision are preferred. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. In the method based on the physical collision, for example, a sheeter composer (manufactured by Tokuju Kosakusho) or the like is used.

  The melting point of the base particles is preferably higher than the melting points of the conductive part and the solder part. The melting point of the base particles is preferably higher than 160 ° C, more preferably higher than 300 ° C, still more preferably higher than 400 ° C, particularly preferably higher than 450 ° C. In addition, the melting point of the base particles may be lower than 400 ° C. The melting point of the base particles may be 160 ° C. or less. The softening point of the base particles is preferably 260 ° C. or higher. The softening point of the base 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 portions (solder portions, second conductive portions). That is, in the conductive particles, two or more conductive portions may be laminated. When the conductive portion has two or more layers, it is preferable that the conductive particles have solder on an outer surface portion of the conductive portion.

  The solder is preferably a metal having a melting point of 450 ° C. or lower (a low melting point metal). The solder portion is preferably a metal layer having a melting point of 450 ° C. or lower (a low-melting metal layer). 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 (low-melting metal particles) having a melting point of 450 ° C. or less. 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 less. The melting point of the low melting point metal is preferably 300 ° C. or lower, more preferably 160 ° C. or lower. Preferably, the solder in the conductive particles 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. It is at least 70% by weight, particularly preferably at least 90% by weight. When the content of tin contained in the solder in the conductive particles is equal to or larger than the lower limit, the reliability of conduction between the conductive particles and the electrode is further increased.

  The tin content was determined using a high-frequency inductively coupled plasma emission spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or an X-ray fluorescence analyzer ("EDX-800HS" manufactured by Shimadzu Corporation). 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 likely to make a surface contact instead of a point contact, the connection resistance is reduced. 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, so that peeling of the solder and the electrode is more unlikely to occur and the conduction reliability is effectively improved. Become higher.

  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 to the electrode. More preferably, they are a tin-bismuth alloy and a tin-indium alloy.

  The material constituting the solder (solder portion) is preferably a filler material having a liquidus of 450 ° C. or lower based on JIS Z3001: welding terminology. Examples of the composition of the solder include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium, and the like. A tin-indium-based (117 ° C eutectic) or a tin-bismuth-based (139 ° C eutectic) which is low melting point and lead-free 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 includes nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, and manganese. , Chromium, molybdenum, palladium and the like. Further, 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.

  It is preferable that the melting point of the second conductive part is higher than the melting point of the solder part. The melting point of the second conductive part is preferably higher than 160 ° C, more preferably higher than 300 ° C, further preferably higher than 400 ° C, still more preferably higher than 450 ° C, particularly preferably higher than 500 ° C, Preferably it exceeds 600 ° C. Since the above-mentioned solder part has a low melting point, it melts at the time of conductive connection. It is preferable that the second conductive portion does not melt at the time of conductive connection. The conductive particles are preferably used by melting the solder, preferably used by melting the solder portion, used without melting the solder portion and melting the second conductive portion. Preferably. Since the melting point of the second conductive part is higher than the melting point of the solder part, it is possible to melt only the solder part 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, and particularly preferably. It is 50 ° C or higher, most preferably 100 ° C or higher.

  It is preferable that the second conductive portion includes a metal. The metal forming the second conductive portion is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof. Further, tin-doped indium oxide (ITO) may be used as the metal. One of the above metals may be used alone, or two or more thereof may be used in combination.

  The second conductive portion 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 further 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 still more preferably have a copper layer. By using the conductive particles having these preferable conductive portions for the connection between the electrodes, the connection resistance between the electrodes is further reduced. Further, a solder portion can be more easily formed on the surface of these preferable conductive portions.

  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 still more preferably 0.3 μm or less. When the thickness of the solder portion is equal to or more than the lower limit and equal to or less than the upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed at the time of connection between the electrodes. .

  The average particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more, preferably 100 μm or less, more preferably 50 μm or less, still more preferably 40 μm or less, and particularly preferably. Is 30 μm or less. When the average particle diameter of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the solder in the conductive particles can be more efficiently arranged on the electrodes, and the amount of the solder in the conductive particles between the electrodes is increased. The arrangement is easy, and the conduction reliability is further improved.

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

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

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 1% by weight or more, more preferably 2% by weight or more, further preferably 10% by weight or more, particularly preferably 20% by weight or more, and most preferably. It is at least 30% by weight, preferably at most 80% by weight, more preferably at most 60% by weight, further preferably at most 50% by weight. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, solder in the conductive particles can be more efficiently arranged on the electrodes, and more solder in the conductive particles is arranged between the electrodes. And the conduction reliability is further improved. From the viewpoint of further improving conduction reliability, it is preferable that the content of the conductive particles is large.

(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, phenol 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, and an epoxy compound is more preferable. The conductive material preferably contains an epoxy compound. The thermosetting compound may be used alone or in combination of two or more.

  Examples of the epoxy compound include an aromatic 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. Epoxy compounds that are solid at room temperature (23 ° C.) and have a melting temperature equal to or lower than the melting point of the solder are preferred. The melting temperature is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and preferably 40 ° C. or higher. By using the above preferred epoxy compound, at the stage of bonding the connection target members, the viscosity is high, and when acceleration is given by an impact such as conveyance, the first connection target member is connected to the second connection member. The displacement with respect to the target member can be suppressed, and the viscosity of the conductive material can be greatly reduced by the heat at the time of curing, so that the aggregation of the solder can efficiently proceed.

  From the viewpoint of suppressing the generation of black soot, the conductive material preferably contains a thermosetting compound having an isocyanuric skeleton as the thermosetting component and the thermosetting compound. From the viewpoint of increasing the curability of the conductive material and increasing the connection reliability, the thermosetting compound having an isocyanuric skeleton preferably has an epoxy group or a thiirane group, and has an epoxy compound or an isocyanuric skeleton having an isocyanuric skeleton. It is preferably an episulfide compound. Epoxy compounds having an isocyanuric skeleton are particularly preferred. The conductive material may include a thermosetting compound having no isocyanuric skeleton.

  Examples of the thermosetting compound having an isocyanuric skeleton include triazine triglycidyl ether and the like, and TEPIC series (TEPIC-G, TEPIC-S, TEPIC-SS, TEPIC-HP, TEPIC-L, TEPIC-) manufactured by Nissan Chemical Industries, Ltd. PAS, TEPIC-VL, and TEPIC-UC).

  The episulfide compound having the isocyanuric skeleton can be obtained, for example, by converting an epoxy group of an epoxy compound having an isocyanuric skeleton to a thiirane group. This conversion method is known.

  From the viewpoint of further suppressing the occurrence of black soot, the molecular weight of the thermosetting compound having the isocyanuric skeleton is preferably 200 or more, more preferably 300 or more, preferably 1,000 or less, more preferably 600 or less. is there.

  From the viewpoint of improving the curability of the conductive material and improving the connection reliability, the conductive material has an isocyanuric skeleton together with the thermosetting compound having an isocyanuric skeleton as the thermosetting component and the thermosetting compound. It is preferable to include a thermosetting compound that is not used. From the viewpoint of enhancing the curability of the conductive material and the heat resistance of the cured product, and improving the connection reliability, the thermosetting compound having no isocyanuric skeleton preferably has an aromatic skeleton or an alicyclic skeleton, It is preferable that the compound is a thermosetting compound having no isocyanuric skeleton and having an aromatic skeleton or an alicyclic skeleton.

  The total 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, further preferably 50% by weight or more, and preferably 99% by weight. Or less, more preferably 98% by weight or less, further preferably 90% by weight or less, particularly preferably 80% by weight or less. When the content of the thermosetting compound is equal to or more than the lower limit and equal to or less than the upper limit, the solder in the conductive particles is more efficiently arranged on the electrodes, and the displacement between the electrodes is further suppressed. Can be further improved in the conduction reliability. From the viewpoint of further improving the impact resistance, the content of the thermosetting compound is preferably higher. From the viewpoint of further improving the curability and viscosity of the conductive material and further improving the connection reliability, the content of the epoxy compound in the conductive material of 100% by weight is preferably 10% by weight or more, more preferably 15% by weight or more. % By weight, preferably 50% by weight or less, more preferably 30% by weight or less.

  From the viewpoint of further suppressing the generation of black soot, the content of the thermosetting component having the isocyanuric skeleton is preferably 5% by weight or more, more preferably 10% by weight or more in 100% by weight of the conductive material. And preferably 30% by weight or less, more preferably 20% by weight or less.

  From the viewpoint of further suppressing the generation of black soot, the content of the thermosetting compound having the isocyanuric skeleton in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 10% by weight or more. And preferably 30% by weight or less, more preferably 20% by weight or less.

  From the viewpoint of enhancing the curability of the conductive material and improving the connection reliability, the content of the thermosetting compound having no isocyanuric skeleton in 100% by weight of the conductive material is preferably 1% by weight or more, more preferably 1% by weight or more. Is at least 2% by weight, preferably at most 20% by weight, more preferably at most 15% by weight.

  From the viewpoint of further suppressing the occurrence of black soot, the weight ratio of the content of the compound having the isocyanuric skeleton to the content of the flux (content of the compound having the isocyanuric skeleton / content of the flux) is preferable. Is 0.5 or more, more preferably 3 or more, preferably 20 or less, more preferably 15 or less, and may be 1 or less. When the flux includes a flux having an isocyanuric skeleton, the content of the flux includes the content of the flux having an isocyanuric skeleton.

  From the viewpoint of further suppressing the generation of black soot, the weight ratio of the content of the thermosetting component having the isocyanuric skeleton to the content of the flux (content of the thermosetting component having the isocyanuric skeleton / flux of the flux) Content) is preferably 0.5 or more, more preferably 3 or more, preferably 20 or less, and more preferably 15 or less.

  From the viewpoint of further suppressing the generation of black soot, the weight ratio of the content of the thermosetting compound having the isocyanuric skeleton to the content of the flux (content of the thermosetting compound having the isocyanuric skeleton / flux of the flux) Content) is preferably 0.5 or more, more preferably 3 or more, preferably 20 or less, and more preferably 15 or less.

  From the viewpoint of further suppressing the generation of black soot, the weight ratio of the content of the compound having the isocyanuric skeleton to the content of the conductive particles (content of the compound having the isocyanuric skeleton / content of the conductive particles) ) Is preferably at least 0.05, more preferably at least 0.1, preferably at most 0.5, more preferably at most 0.4.

  From the viewpoint of further suppressing the generation of black soot, the weight ratio of the content of the thermosetting component having the isocyanuric skeleton to the content of the conductive particles (content of the thermosetting component having the isocyanuric skeleton / Content of the conductive particles) is preferably 0.05 or more, more preferably 0.1 or more, preferably 0.5 or less, more preferably 0.4 or less.

  From the viewpoint of further suppressing the generation of black soot, the weight ratio of the content of the thermosetting compound having the isocyanuric skeleton to the content of the conductive particles (content of the thermosetting compound having the isocyanuric skeleton / Content of the conductive particles) is preferably 0.05 or more, more preferably 0.1 or more, preferably 0.5 or less, more preferably 0.4 or less.

(Thermosetting agent)
The thermosetting agent thermosets the thermosetting compound. Examples of the thermal curing agent include an imidazole curing agent, a phenol curing agent, a thiol curing agent, an amine curing agent, an acid anhydride curing agent, a thermal cation initiator (thermal cation curing agent), and a thermal radical generator. Only one kind of the thermosetting agent may be used, or two or more kinds thereof may be used in combination.

  From the viewpoint of further suppressing the generation of black soot, a thermosetting agent or a thiol curing agent having an isocyanuric skeleton is preferable. From the viewpoint of further suppressing the generation of black soot, a thermosetting agent having an isocyanuric skeleton is preferable, and a thiol curing agent is preferable. The conductive material may include a thermosetting agent having no isocyanuric skeleton.

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

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

  The solubility parameter of the thiol curing agent is preferably 9.5 or more, and more preferably 12 or less. The solubility parameter is calculated by the Fedors method. For example, the solubility parameter of trimethylolpropane tris-3-mercaptopropionate is 9.6, and the solubility parameter of dipentaerythritol hexa-3-mercaptopropionate is 11.4.

  The amine curing agent is not particularly limited, and hexamethylene diamine, octamethylene diamine, decamethylene diamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5.5]. Undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine, diaminodiphenylsulfone, and the like.

  Examples of the thermal cation initiator include an iodonium-based cation curing agent, an oxonium-based cation curing agent, and a sulfonium-based cation curing agent. Examples of the iodonium-based cationic curing agent include bis (4-tert-butylphenyl) iodonium hexafluorophosphate. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium-based cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

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

  Examples of the thermosetting agent having the isocyanuric skeleton include tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate.

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

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

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

  From the viewpoint of further suppressing the occurrence of black soot, the molecular weight of the thermosetting agent having the isocyanuric skeleton is preferably 200 or more, more preferably 300 or more, preferably 1,000 or less, more preferably 600 or less. .

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably at least 0.01 part by weight, more preferably at least 1 part by weight, preferably at most 200 parts by weight, more preferably at most 200 parts by weight, based on 100 parts by weight of the thermosetting compound. 100 parts by weight or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is at least the above lower limit, it is easy to sufficiently cure the conductive material. When the content of the thermosetting agent is equal to or less than the above upper limit, the surplus thermosetting agent not involved in the curing after the curing hardly remains, and the heat resistance of the cured product is further increased.

  From the viewpoint of further suppressing the generation of black soot, the content of the thermosetting agent having the isocyanuric skeleton in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 10% by weight or more. , Preferably 30% by weight or less, more preferably 20% by weight or less.

(Phosphate compound)
From the viewpoint of more efficiently collecting the solder on the electrodes, the conductive material preferably contains a phosphate compound. The phosphoric acid compound may be used alone or in combination of two or more.

  From the viewpoint of more efficiently collecting solder on the electrode, the phosphoric acid compound is preferably phosphorous acid or a phosphite, more preferably a phosphite, and a phosphite Is more preferably a phosphite represented by the following formula (11).

  In the formula (11), R is preferably an organic group having 1 to 15 carbon atoms, and more preferably an organic group having 6 to 15 carbon atoms.

  The phosphoric acid compound preferably has one or more organic groups having 6 to 15 carbon atoms, more preferably one or more hydrocarbon groups having 6 to 15 carbon atoms, and more preferably 6 or more carbon atoms. It is particularly preferable to have one or more aryl groups of 15 or less. The phosphoric acid compound may have two of each of these groups. In particular, phosphorous acid having one or more aryl groups is preferable, phosphorous acid having two aryl groups is more preferable, and diphenylphosphorous acid or dibenzylphosphorous acid is further preferable. Phosphorous acid having two aryl groups may have one phenyl group, may have two phenyl groups, may have one benzyl group, and may have one benzyl group. You may have two.

  The pH of an aqueous solution obtained by dissolving 1 g of the phosphoric acid compound in 10 g of water is measured. The pH of the aqueous solution is preferably 3.5 or more, more preferably 3.7 or more, still more preferably 5 or more, and preferably 6 or less. The pH of the aqueous solution may be 5 or less. When the pH of the aqueous solution is equal to or higher than the lower limit and equal to or lower than the upper limit, solder collects more efficiently on the electrode. The pH of the aqueous solution may exceed 3, may exceed 4, may exceed 5, may be 7 or more.

  The pH of the aqueous solution can be measured using a pH meter ("D-72" manufactured by HORIBA) and an electrode Touh pH electrode 9615-10D.

  From the viewpoint of more efficiently collecting the solder on the electrodes, the phosphite is preferably a phosphite monoester or a phosphite diester. From the viewpoint of more efficiently collecting the solder on the electrode, the phosphoric acid compound preferably does not have a (meth) acryloyl group, and is preferably not a (meth) acrylate compound.

  The phosphoric acid compound may be phosphoric acid or a reaction product of a phosphoric acid compound and an imidazole compound.

  From the viewpoint of more efficiently disposing the solder on the electrode and further improving conduction reliability, the content of the phosphoric acid compound is preferably 0.1% by weight or more in 100% by weight of the conductive material. It is preferably at least 1% by weight, preferably at most 15% by weight, more preferably at most 10% by weight.

(flux)
The conductive material contains a flux. The use of flux allows the solder to be more effectively placed on the electrodes. When the solder is subjected to a flux action by the flux, black soot is easily generated. However, in the present invention, since a compound having an isocyanuric skeleton is used, generation of black soot can be suppressed. The flux is not particularly limited. As the flux, a flux generally used for solder joining 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 rosin. And the like. Only one type of the above flux may be used, or two or more types may be used in combination.

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

  The rosin is a rosin containing abietic acid as a main component. The flux is preferably a rosin, and more preferably abietic acid. The use of this preferred flux further increases the reliability of conduction between the electrodes.

  From the viewpoint of further suppressing the occurrence of black soot, a flux having an isocyanuric skeleton is preferable. The conductive material may include a flux having no isocyanuric skeleton.

  Examples of the flux having an isocyanuric skeleton include a compound having a carboxyl group and an isocyanuric skeleton. Commercially available fluxes having an isocyanuric skeleton include CIC acid and MACIC-1 (manufactured by Shikoku Chemicals). The conductive material may include a flux having no isocyanuric skeleton.

  The activation temperature (melting point) of the flux is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, even more preferably 80 ° C. or higher, preferably 200 ° C. or lower, more preferably 190 ° C. or lower, and even more preferably 160 ° C. or lower. C. or lower, more preferably 150.degree. C. or lower, even more preferably 140.degree. C. or lower. When the activation temperature of the flux is equal to or higher than the lower limit and equal to or lower than the upper limit, the flux effect is exhibited more effectively, and the solder is more efficiently arranged on the electrode. The activation temperature (melting point) of the flux is preferably 80 ° C. or more and 190 ° C. or less. The activation temperature (melting point) of the above-mentioned flux is particularly preferably from 80 ° C to 140 ° C.

  The above-mentioned flux whose activation temperature (melting point) of the flux is 80 ° C. or more and 190 ° C. or less includes succinic acid (melting point 186 ° C.), glutaric acid (melting point 96 ° C.), adipic acid (melting point 152 ° C.), pimelic acid (melting point Dicarboxylic acid such as suberic acid (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), and malic acid (melting point 130 ° C.).

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

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

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

  The flux may be dispersed in a conductive material or may adhere to the surface of the conductive particles.

  Since 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 and the portion of the connection target member around the electrode are compared, the thermal conductivity of the electrode portion is equal to that of the connection target member portion around the electrode. When the temperature is higher than the thermal conductivity, the temperature rise of the electrode portion is fast. At a stage beyond the melting point of the solder in the conductive particles, the solder in the conductive particles dissolves, but the oxide film formed on the surface is not removed because the melting point (activation temperature) of the flux has not been reached. In this state, since the temperature of the electrode portion reaches the melting point (activation temperature) of the flux first, the oxide film on the surface of the solder of the conductive particles coming on the electrode is preferentially removed, and By neutralizing the charge on the surface of the solder in the conductive particles by the generated flux, the solder can be spread on the surface of the electrode. Thereby, the solder can be efficiently aggregated on the electrode.

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

  Examples of the flux that releases cations upon heating include the above-mentioned thermal cation initiators.

  From the viewpoint of further suppressing the generation of black soot, the molecular weight of the flux having the isocyanuric skeleton is preferably 200 or more, more preferably 300 or more, preferably 1,000 or less, more preferably 600 or less.

  In 100% by weight of the conductive material, the content of the flux is preferably 0.5% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. When the content of the flux is equal to or more than the lower limit and equal to or less than the upper limit, an oxide film is more difficult to be formed on the surface of the solder and the electrode, and furthermore, the oxide film formed on the surface of the solder and the electrode is more effectively formed. Can be removed.

  From the viewpoint of further suppressing the generation of black soot, the content of the flux having the isocyanuric skeleton is preferably 5% by weight or more, more preferably 10% by weight or more, in 100% by weight of the conductive material. Is at most 30% by weight, more preferably at most 20% by weight.

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

(Connection structure and method of manufacturing connection structure)
The connection structure according to the present invention includes: a first connection target member having at least one first electrode on a surface; a second connection target member having at least one second electrode on a surface; And a connection portion connecting the second connection target member. In the connection structure according to the present invention, the material of the connection portion is the above-described conductive material, and the connection portion is a cured product of the above-described conductive material. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

  The method for manufacturing a connection structure includes a step of disposing the conductive material on a surface of a first connection target member having at least one first electrode on a surface using the conductive material described above; On the surface of the material opposite to the first connection target member side, a second connection target member having at least one second electrode on the surface is formed by combining the first electrode and the second electrode. A step of arranging the first connection target member and the second connection target member 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 from the conductive material, and electrically connecting the first electrode and the second electrode by a solder portion in the connection portion. Preferably, the conductive material is heated to a temperature equal to or higher than the curing temperature of the thermosetting component and the thermosetting compound.

  In the connection structure and the method for manufacturing the connection structure according to the present invention, since the specific conductive material is used, the solder in the plurality of conductive particles easily collects between the first electrode and the second electrode. In addition, the solder can be efficiently arranged on the electrodes (lines). Further, it is difficult for a part of the solder to be arranged in a region (space) where the electrode is not formed, and the amount of the solder arranged in the region where the electrode is not formed can be considerably reduced. Therefore, the reliability of conduction between the first electrode and the second electrode can be improved. In addition, electrical connection between horizontally adjacent electrodes that must not be connected can be prevented, and insulation reliability can be improved.

  Further, in order to efficiently arrange the solder in the plurality of conductive particles on the electrodes and to considerably reduce the amount of the solder arranged in the region where the electrodes are not formed, a conductive paste is used instead of the conductive film. Preferably, it is used.

  The thickness of the solder portion between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, preferably 100 μm or less, more preferably 80 μm or less. The solder wet area on the surface of the electrode (the area where the solder is in contact with 100% of the exposed area of the electrode) is preferably at least 50%, more preferably at least 60%, even more preferably at least 70%, preferably at least 70%. Is 100% or less.

  In the method for manufacturing a connection structure according to the present invention, in the step of arranging the second member to be connected and the step of forming the connection portion, no pressure is applied, and the second connection is applied to the conductive material. It is preferable that the weight of the target member is added, and in the step of arranging the second connection target member and the step of forming the connection portion, the conductive material exceeds the force of the weight of the second connection target member. Preferably, no pressure is applied. In these cases, the uniformity of the amount of solder can be further improved in the plurality of solder portions. Further, the thickness of the solder portion can be more effectively increased, so that a large amount of the solder in the plurality of conductive particles easily gathers between the electrodes, and the solder in the plurality of conductive particles can be more efficiently applied to the electrodes (lines). It can be arranged in a way. Further, it is difficult for a part of the solder in the plurality of conductive particles to be arranged in the region (space) where the electrode is not formed, and the amount of the solder in the conductive particle arranged in the region where the electrode is not formed is further increased. Can be reduced. Therefore, the reliability of conduction between the electrodes can be further improved. In addition, electrical connection between horizontally adjacent electrodes that should not be connected can be further prevented, and insulation reliability can be further improved.

  Further, in the step of arranging the second member to be connected and the step of forming the connecting portion, if the weight of the second member to be connected is added to the conductive material without applying pressure, the connecting portion is formed. Before being formed, the solder disposed in the region (space) where the electrode is not formed becomes more easily collected between the first electrode and the second electrode, and the solder in the plurality of conductive particles is transferred to the electrode ( Line) can also be arranged more efficiently. In the present invention, a configuration in which a conductive paste is used instead of a conductive film and a configuration in which pressure is not applied and the weight of the second connection target member is added to the conductive paste are employed. Doing so has great significance in obtaining the effects of the present invention at a higher level.

  WO 2008/023452 A1 describes that from the viewpoint of efficiently moving the solder powder by flowing it down to the electrode surface, it is advisable to apply a predetermined pressure at the time of bonding. From the viewpoint of forming, for example, it is described that the pressure is 0 MPa or more, preferably 1 MPa or more. Further, even if the pressure intentionally applied to the adhesive tape is 0 MPa, the pressure of the member arranged on the adhesive tape is reduced. It is described that a predetermined pressure may be applied to the adhesive tape by its own weight. WO 2008/023452 A1 describes that the pressure intentionally applied to the adhesive tape may be 0 MPa. However, the difference between the effect when the pressure exceeding 0 MPa is applied and the case where the pressure is set to 0 MPa is not described. Not listed. In WO2008 / 023452A1, the importance of using a paste-like conductive paste instead of a film-like one is not recognized at all.

  If a conductive paste is used instead of a conductive film, the thickness of the connection portion and the solder portion can be easily adjusted depending on the amount of the conductive paste applied. On the other hand, in the case of a 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 a conductive film having a predetermined thickness. There is. Further, in the conductive film, compared with the conductive paste, the melt viscosity of the conductive film cannot be sufficiently reduced 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 one embodiment of the present invention.

  The connection structure 1 shown in FIG. 1 includes a first connection target member 2, a second connection target member 3, and a connection connecting the first connection target member 2 and the second connection target member 3. Unit 4. The connection part 4 is formed of the above-described conductive material. In the present embodiment, the conductive material includes solder particles as conductive particles.

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

  The first connection target member 2 has a plurality of first electrodes 2a on a 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 a solder 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 material portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In a region different from the solder portion 4A (cured material portion 4B portion), there is no solder separated from the solder portion 4A. If the amount is small, the solder may be present in a region (cured material 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 2a and the second electrode 3a, and after the plurality of solder particles have melted, Solidifies after the electrode surface wets and spreads to form the solder portion 4A. Therefore, the connection area between the solder portion 4A and the first electrode 2a and the connection area between the solder portion 4A and the second electrode 3a are increased. That is, by using the solder particles, the solder portion 4A, the first electrode 2a, and the solder are compared with a case where the outer surface portion of the conductive portion is made of a metal such as nickel, gold, or copper. The contact area between the portion 4A and the second electrode 3a increases. Therefore, conduction reliability and connection reliability in the connection structure 1 are improved.

  In general, the flux gradually deactivates by heating.

  In the connection structure 1 shown in FIG. 1, all of the solder portions 4A are located in areas facing each other between the first and second electrodes 2a and 3a. The connection structure 1X of the modification shown in FIG. 3 differs from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. The connection part 4X has a solder part 4XA and a cured material part 4XB. Like the connection structure 1X, most of the solder portions 4XA are located in regions where the first and second electrodes 2a and 3a face each other, and a portion of the solder portion 4XA is formed in the first and second electrodes. The electrodes 2a and 3a may protrude laterally from the facing regions. The solder portion 4XA protruding laterally from the region where the first and second electrodes 2a and 3a face each other is a part of the solder portion 4XA and is not a solder separated from the solder portion 4XA. In this embodiment, although the amount of the solder separated from the solder portion can be reduced, the solder separated from the solder portion may be present in the cured product portion.

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

  From the viewpoint of further improving the conduction reliability, a portion where the first electrode and the second electrode face each other in the laminating direction of the first electrode, the connection portion, and the second electrode is viewed. In some cases, 50% or more (more preferably 60% or more, further preferably 70% or more, particularly preferably 80% or more) of 100% of the area of the portion where the first electrode and the second electrode face each other. (Most preferably 90% or more), it is preferable that the solder portion in the connection portion is disposed.

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

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

  The conductive material 11 is disposed on the surface of the first connection target member 2 on which the first electrode 2a is provided. After disposing the conductive material 11, 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.

  A method for arranging the conductive material 11 is not particularly limited, and examples thereof include application using a dispenser, screen printing, and ejection using an inkjet device.

  Further, the second connection target member 3 having the second electrode 3a on the surface (lower surface) is prepared. Next, as shown in FIG. 2B, in the conductive material 11 on the surface of the first connection target member 2, on the surface of the conductive material 11 opposite to the first connection target member 2 side, The second connection target member 3 is arranged (second step). The second connection target member 3 is arranged on the surface of the conductive material 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a face 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 (binder). At the time of this heating, the solder particles 11A existing 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 effectively gather between the first electrode 2a and the second electrode 3a. Further, the solder particles 11A are melted and joined to each other. The thermosetting component 11B is thermoset. As a result, as shown in FIG. 2C, the connection portion 4 connecting the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. The connection portion 4 is formed by the conductive material 11, the solder portion 4A is formed by joining the plurality of solder particles 11A, and the cured product portion 4B is formed by thermosetting the thermosetting component 11B.

  In the present embodiment, it is preferable not to apply pressure 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 forming the connection part 4, the solder particles 11A effectively gather between the first electrode 2a and the second electrode 3a. In addition, in at least one of the second step and the third step, if pressure is applied, the action of solder particles gathering between the first electrode and the second electrode is hindered. Tendency to increase.

  Further, in the present embodiment, since no pressurization is performed, when the second connection target member is overlapped with the first connection target member coated with the conductive material, the electrode of the first connection target member is Even when the first connection target member and the second connection target member are overlapped in a state where the alignment of the second connection target member with the electrode is shifted, the shift is corrected and the first connection target member is corrected. The electrode of the member and the electrode of the second member to be connected can be connected (self-alignment effect). This is because the molten solder that has self-agglomerated between the electrode of the first member to be connected and the electrode of the second member to be connected is connected to the electrode of the first member to be connected and the electrode of the second member to be connected. Since the area where the solder in contact with the other components of the conductive material is minimized becomes more stable in terms of energy, the connection structure with the minimum area is the force that makes the connection structure aligned. That's why. In this case, it is desirable that the conductive material is not cured, and that the viscosity of the components other than the conductive particles of the conductive material is sufficiently low at the temperature and time.

  Thus, the connection structure 1 shown in FIG. 1 is obtained. Note that the second step and the third step may be performed continuously. Further, after performing the second step, the obtained laminate of the first connection target member 2, the conductive material 11, and the second connection target member 3 is moved to a heating unit, and the third connection target member 2, the conductive material 11, and the second connection target member 3 are moved to the heating unit. A step may be performed. In order to perform the heating, the laminate may be arranged on a heating member, or the laminate may be arranged 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 further preferably 200 ° C. or lower.

  As a heating method in the third step, a method of heating the entire connection structure using a reflow furnace or an oven at a temperature equal to or higher than the melting point of the solder and the curing temperature of the thermosetting component, Is locally heated.

  The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include electronic components such as a semiconductor chip, a semiconductor package, an LED chip, an LED package, a capacitor and a diode, a resin film, a printed board, a flexible printed board, and a flexible board. Electronic components such as circuit boards such as flat cables, rigid flexible boards, glass epoxy boards, and glass boards are exemplified. 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. It is preferable that the second connection target member is a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. A resin film, a flexible printed board, a flexible flat cable, and a rigid flexible board have a property of high flexibility and relatively light weight. When a conductive film is used for connecting such a connection target member, the solder tends to hardly collect on the electrodes. On the other hand, even if a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board is used by using a conductive paste, by efficiently collecting solder on the electrodes, the reliability of conduction between the electrodes is improved. Can be sufficiently increased. When using a resin film, a flexible printed board, a flexible flat cable or a rigid flexible board, the reliability of conduction between the electrodes due to no pressurization is lower than when using other connection target members such as semiconductor chips. The improvement effect can be obtained even more effectively.

  The form of the connection target member includes a peripheral and an area array. As a feature of each member, in the peripheral substrate, the electrodes exist only on the outer peripheral portion of the substrate. In the area array substrate, electrodes exist in a plane.

  Examples of the electrodes 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 member to be connected 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 member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. Note that when the electrode is an aluminum electrode, the electrode may be an electrode formed of only aluminum or an electrode in which an aluminum layer is stacked on a surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

  The form of the connection target member includes a peripheral and an area array. As a feature of each member, in the peripheral substrate, the electrodes exist only on the outer peripheral portion of the substrate. In the area array substrate, electrodes exist in a plane.

  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:
"YL980" manufactured by Mitsubishi Chemical Corporation, bisphenol A-type epoxy resin "TEPIC-PAS" manufactured by Nissan Chemical Industries, Ltd. Epoxy compound having an isocyanuric skeleton Modified product of TEPIC-PAS: Epoxy group of "TEPIC" manufactured by Nissan Chemical Industries, Ltd. Compound (synthetic product) converted to a group, an episulfide compound having an isocyanuric skeleton “TEPIC-VL” manufactured by Nissan Chemical Industries, Ltd.
"TEPIC-UC" manufactured by Nissan Chemical Industries, Ltd.

Thermosetting agent:
"HXA3922HP" manufactured by Asahi Kasei E-Materials
"TEMPIC" manufactured by SC Organic Chemical Industry Co., Ltd.

Curing accelerator:
"2MA-OK" manufactured by Shikoku Chemical Industry Co., Ltd., imidazole curing accelerator

Phosphate compounds:
Johoku Chemical Industry Co., Ltd. "JP260", diphenyl hydro Fen _{phosphite, (C 6 H 5 -O-)} 2 P (= O) H

flux:
Glutaric acid "CIC" manufactured by Shikoku Chemicals
"MACIC-1" manufactured by Shikoku Chemicals

Conductive particles:
SnBi solder particles (average particle diameter 30 μm), manufactured by Mitsui Kinzoku Co., Ltd., Sn42Bi58

(Examples 1 to 11 and Comparative Example 1)
(1) Preparation of anisotropic conductive paste The components shown in Tables 1 and 2 below were blended in the amounts shown in Tables 1 and 2 below to obtain an anisotropic conductive paste.

(2) Production of First Connection Structure (Area Array Substrate) As a first connection target member, a copper electrode of 250 μm at a pitch of 400 μm was formed on the surface of a semiconductor chip body (size 5 × 5 mm, thickness 0.4 mm). And a semiconductor chip having a passivation film (polyimide, thickness 5 μm, opening diameter of the electrode part 200 μm) formed on the outermost surface was prepared. The number of copper electrodes is 10 × 10 per semiconductor chip, for a total of 100.

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

  An anisotropic conductive paste immediately after preparation was applied on the upper surface of the glass epoxy substrate so as to have a thickness of 100 μm to form an anisotropic conductive paste layer. Next, a semiconductor chip was laminated on the upper surface of the anisotropic conductive paste layer such that the electrodes faced each other. The weight of the semiconductor chip is added to the anisotropic conductive paste layer. From this state, heating was performed so that the temperature of the anisotropic conductive paste layer became 139 ° C. (the melting point of the solder) 5 seconds after the start of the temperature rise. Further, 15 seconds after the start of the temperature rise, the anisotropic conductive paste layer was heated so that the temperature of the layer became 160 ° C., and the anisotropic conductive paste was cured to obtain a connection structure. No pressure was applied during heating.

(3) Production of Second Connection Structure (Peripheral Substrate) As a first connection target member, a copper electrode of 250 μm at a pitch of 400 μm was formed on the surface of a semiconductor chip body (size 5 × 5 mm, thickness 0.4 mm). A semiconductor chip which is disposed (peripheral) on the outer periphery of the chip and has a passivation film (polyimide, thickness 5 μm, opening diameter of the electrode portion 200 μm) formed on the outermost surface was prepared. The number of copper electrodes is 36 in total of 10 × 4 sides per semiconductor chip.

  As a second member to be connected, the same pattern as the electrode of the first member to be connected is formed on the surface of the glass epoxy substrate body (size 20 × 20 mm, thickness 1.2 mm, material FR-4). The step between the surface of the copper electrode and the surface of the solder resist film where the copper electrode is disposed and the solder resist film is formed in the region where the copper electrode is not disposed is 15 μm, and the solder resist film is formed of copper. It protrudes from the electrode.

  An anisotropic conductive paste immediately after fabrication was applied to a peripheral portion on the upper surface of the glass epoxy substrate so as to have a thickness of 100 μm, thereby forming an anisotropic conductive paste layer. Next, a semiconductor chip was laminated on the upper surface of the anisotropic conductive paste layer such that the electrodes faced each other. The weight of the semiconductor chip is added to the anisotropic conductive paste layer. From this state, heating was performed so that the temperature of the anisotropic conductive paste layer became 139 ° C. (the melting point of the solder) 5 seconds after the start of the temperature rise. Further, 15 seconds after the start of the temperature rise, the anisotropic conductive paste layer was heated so that the temperature of the anisotropic conductive paste layer became 160 ° C., and the anisotropic conductive paste was cured to obtain a connection structure. No pressure was applied during heating.

(Evaluation)
(1) Viscosity The melting point (ηmp) of the solder in the conductive particles of the anisotropic conductive paste at the melting point (° C.) was determined using STRESSTECH (manufactured by EOLOGICA) at a strain control of 1 rad, a frequency of 1 Hz, and a heating rate of 20 ° C./min. , And a measurement temperature range of 40 to 200 ° C.

(2) Generation of Black Soot Whether or not black soot derived from solder was contained in the connection portions (cured material portions) of the obtained first and second connection structures was evaluated. The occurrence of black soot was determined based on the following criteria.

[Criteria for black soot]
○○○: No black soot and no lightly colored spots ○○: No black soot and some lightly colored spots ○: Very little black soot (to the extent not affecting connection resistance)
△: Slight black soot (a little influence on connection resistance)
×: Black soot is generated (a degree that significantly affects connection resistance)

(3) Accuracy of Arrangement of Solder on Electrode In the obtained first and second connection structures, the first electrode and the second electrode are arranged in the stacking direction of the first electrode, the connection portion, and the second electrode. When the opposing portion of the first electrode and the second electrode is viewed, the ratio X of the area where the solder portion in the connection portion is arranged to 100% of the area of the opposing portion of the first electrode and the second electrode is evaluated. did. The placement accuracy of the solder on the electrode was determined based on the following criteria.

[Criteria for determining placement accuracy of solder on electrodes]
○: Ratio X is 95% or more ○: Ratio X is 90% or more and less than 95% ：: Ratio X is 80% or more and less than 90% ：: Ratio X is 60% or more and less than 80% X: Ratio X is less than 60%

(4) Conduction reliability between upper and lower electrodes In the obtained first and second connection structures (n = 15), the connection resistance between the upper and lower electrodes was measured by a four-terminal method. The average value of the connection resistance was calculated. The connection resistance can be determined by measuring the voltage when a constant current flows from the relationship of voltage = current × resistance. The conduction reliability was determined according to the following criteria.

[Criteria for continuity reliability]
○: Average connection resistance is 8.0Ω or less ○: Average connection resistance exceeds 8.0Ω and 10.0Ω or less △: Average connection resistance exceeds 10.0Ω and 15.0Ω or less × : The average value of the connection resistance exceeds 15.0Ω

(5) Insulation Reliability Between Adjacent Electrodes The obtained first and second connection structures (n = 15) are left in an atmosphere at a temperature of 85 ° C. and a humidity of 85% for 100 hours, and then adjacent to each other. 5 V was applied between the electrodes, and the resistance was measured at 25 points. The insulation reliability was determined based on the following criteria.

[Insulation reliability criteria]
○: average connection resistance value of 10 ⁷ Ω or more ○: average connection resistance value of 10 ⁶ Ω or more and less than 10 ⁷ Ω Δ: average connection resistance value of 10 ⁵ Ω or more and less than 10 ⁶ Ω ×: connection Average value of resistance is less than 10 ⁵ Ω

  The results are shown in Tables 1 and 2 below.

  A similar tendency was observed when a flexible printed board, a resin film, a flexible flat cable, and a rigid flexible board were used.

1, 1X Connection structure 2 First connection target member 2a First electrode 3 Second connection target member 3a Second electrode 4, 4X Connection part 4A, 4XA Solder part 4B, 4XB … Cured part 11… Conductive material 11A… Solder particles (conductive particles)
11B: thermosetting component 21: conductive particles (solder particles)
31 conductive particles 32 base particles 33 conductive part (conductive part having solder)
33A: second conductive portion 33B: solder portion 41: conductive particles 42: solder portion

Claims (14)

On the outer surface portion of the conductive portion, a plurality of conductive particles having solder, a thermosetting component, and a flux,
As the thermosetting component or the flux, including a compound having an isocyanuric skeleton,
A conductive material, wherein the viscosity of the conductive material at the melting point of the solder in the conductive particles is 0.1 Pa · s or more and 20 Pa · s or less.   The conductive material according to claim 1, wherein a weight ratio of the content of the compound having an isocyanuric skeleton to the content of the flux is 0.5 or more and 20 or less.   The conductive material according to claim 1, wherein a weight ratio of the content of the compound having an isocyanuric skeleton to the content of the conductive particles is 0.05 or more and 0.5 or less.   The conductive material according to any one of claims 1 to 3, wherein the compound having an isocyanuric skeleton has a molecular weight of 200 or more and 1000 or less.   The conductive material according to any one of claims 1 to 4, wherein the thermosetting component includes a thermosetting compound having an isocyanuric skeleton or a thermosetting agent having an isocyanuric skeleton.   The conductive material according to claim 5, wherein the thermosetting component includes a thermosetting compound having an isocyanuric skeleton.   The conductive material according to any one of claims 1 to 6, further comprising a thermosetting compound having no isocyanuric skeleton as the thermosetting component.   The conductive material according to claim 7, comprising, as the thermosetting component, a thermosetting compound having an isocyanuric skeleton and a thermosetting compound having no isocyanuric skeleton.   The conductive material according to claim 7, wherein the thermosetting compound having no isocyanuric skeleton is a thermosetting compound having no isocyanuric skeleton and having an aromatic skeleton or an alicyclic skeleton.   The conductive material according to any one of claims 1 to 9, comprising a phosphate compound.   The conductive material according to claim 1, wherein the conductive particles are solder particles.   The conductive material according to any one of claims 1 to 11, which is a liquid at 25 ° C and is a conductive paste. A first member to be connected having at least one first electrode on its surface;
A second member to be connected having at least one second electrode on its surface;
A connection unit that connects the first connection target member and the second connection target member,
The connection portion is a cured product of the conductive material according to any one of claims 1 to 12,
A connection structure, wherein the first electrode and the second electrode are electrically connected by a solder part in the connection part.   When a portion where the first electrode and the second electrode face each other is viewed in the laminating direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode 14. The connection structure according to claim 13, wherein the solder portion in the connection portion is arranged in 50% or more of 100% of the area of the portion facing the second electrode. 15.

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