JPWO2017033934A1 - Conductive material and connection structure - Google Patents

Abstract

Provided is a conductive material capable of selectively disposing solder in conductive particles on an electrode and improving conduction reliability. The conductive material according to the present invention includes a plurality of conductive particles having solder on the outer surface portion of the conductive portion and a thermosetting component, and each of the conductive particles and the thermosetting component is 25 ° C. When the differential scanning calorimetry is performed by heating at a temperature rising rate of 10 ° C./min from the temperature range showing the endothermic peak derived from the melting of the solder in the conductive particles, and the thermosetting component is cured. The temperature range showing the exothermic peak derived at least partially overlaps.

Description

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

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

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

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

  As an example of the anisotropic conductive material, Patent Document 1 described below describes an anisotropic conductive material including conductive particles and a resin component that cannot be cured at the melting point of the conductive particles. Specifically, the conductive particles include tin (Sn), indium (In), bismuth (Bi), silver (Ag), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd ), Metals such as gallium (Ga) and thallium (Tl), and alloys of these metals.

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

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

JP 2004-260131 A WO2008 / 023452A1

  In an anisotropic conductive material including conductive particles having a conventional solder powder or a solder layer on the surface, the solder powder or conductive particles may not be efficiently disposed on the electrode (line).

  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 formed on the electrodes (lines). May not be placed. Moreover, in the Example of patent document 1, in order to move a solder fully at the temperature more than melting | fusing point of solder, it is hold | maintained at fixed temperature, and the manufacturing efficiency of a connection structure becomes low. When mounting is performed with the temperature profile shown in FIG. 8 of Patent Document 1, the manufacturing efficiency of the connection structure is lowered.

  Moreover, the adhesive tape of patent document 2 is a film form, and is not a paste form. In the adhesive tape having the composition as described in Patent Document 2, it is difficult to efficiently arrange the solder powder on the electrode (line). For example, in the adhesive tape described in Patent Document 2, a part of the solder powder is easily placed in a region (space) where no electrode is formed. Solder powder disposed in a region where no electrode is formed does not contribute to conduction between the electrodes.

  The objective of this invention is providing the electrically conductive material which can arrange | position the solder in electroconductive particle selectively on an electrode and can improve conduction | electrical_connection reliability. Another object of the present invention is to provide a connection structure using the conductive material.

  According to a wide aspect of the present invention, the outer surface portion of the conductive portion includes a plurality of conductive particles having solder and a thermosetting component, and each of the conductive particles and the thermosetting component is 25 When the differential scanning calorimetry is performed by heating at a temperature rising rate of 10 ° C./min from 0 ° C., a temperature range showing an endothermic peak derived from melting of the solder in the conductive particles, and curing of the thermosetting component There is provided a conductive material in which at least part of the temperature region exhibiting an exothermic peak derived from is overlapping.

  In a specific aspect of the conductive material according to the present invention, the total calorific value derived from the curing of the thermosetting component in a temperature region below the endothermic peak top temperature derived from melting of the solder in the conductive particles is It is smaller than the total calorific value derived from the curing of the thermosetting component in a temperature region equal to or higher than the endothermic peak top temperature derived from melting of the solder in the conductive particles.

  In a specific aspect of the conductive material according to the present invention, a first exothermic peak top derived from curing of the thermosetting component on a lower temperature side than an endothermic peak top temperature derived from melting of the solder in the conductive particles. There is a second exothermic peak top temperature derived from the curing of the thermosetting component on the higher temperature side than the endothermic peak top temperature derived from the melting of the solder in the conductive particles.

  In a specific aspect of the conductive material according to the present invention, an absolute value of a difference between the endothermic peak top temperature and the first exothermic peak top temperature is 3 ° C. or more and 60 ° C. or less, and the endothermic peak top. The absolute value of the difference between the temperature and the second exothermic peak top temperature is 5 ° C. or more and 60 ° C. or less.

  In a specific aspect of the conductive material according to the present invention, the peak end temperature on the high temperature side of the endothermic peak is lower than the peak end temperature on the high temperature side of the exothermic peak on the highest temperature side.

  In a specific aspect of the conductive material according to the present invention, the end temperature on the high temperature side of the endothermic peak is lower than the peak end temperature on the high temperature side of the exothermic peak on the highest temperature side, and the endothermic peak. The peak start temperature on the low temperature side is higher than the peak start temperature on the low temperature side of the exothermic peak on the lowest temperature side.

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

  On the specific situation with the electrically-conductive material which concerns on this invention, a carboxyl group exists in the outer surface of the said electroconductive particle.

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

  According to a wide aspect of the present invention, a first connection target member having at least one first electrode on the surface, a second connection target member having at least one second electrode on the surface, and the first A connection part connecting the second connection target member and the second connection target member, wherein the connection part is a cured product of the conductive material described above, and the first electrode and the second electrode. Are connected to each other by a solder portion in the connection portion.

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

  The conductive material according to the present invention includes a plurality of conductive particles having solder on the outer surface portion of the conductive portion and a thermosetting component, and each of the conductive particles and the thermosetting component is 25 ° C. When the differential scanning calorimetry is performed by heating at a heating rate of 10 ° C./min from the temperature range showing an endothermic peak derived from melting of the solder in the conductive particles, and curing of the thermosetting component Since the temperature region showing the derived exothermic peak at least partially overlaps, the solder in the conductive particles can be selectively disposed on the electrode, and the conduction reliability can be improved.

FIG. 1 is a schematic diagram illustrating an example of a relationship between an endothermic peak derived from melting of solder in conductive particles and an exothermic peak derived from curing of a thermosetting component in differential scanning calorimetry. FIG. 2 is a cross-sectional view schematically showing a connection structure obtained using a conductive material according to an embodiment of the present invention. 3A to 3C are cross-sectional views for explaining each step of an example of a method for manufacturing a connection structure using a conductive material according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a modification of the connection structure. FIG. 5 is a cross-sectional view showing a first example of conductive particles that can be used as a conductive material. FIG. 6 is a cross-sectional view showing a second example of conductive particles that can be used for the conductive material. FIG. 7 is a cross-sectional view showing a third example of conductive particles that can be used for the conductive material.

  Details of the present invention will be described below.

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

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

  In the present invention, when the differential scanning calorimetry is performed by heating at a temperature increase rate of 25 ° C. to 10 ° C./min, a temperature region showing an endothermic peak derived from melting of the solder in the conductive particles, and the heat The temperature region showing the exothermic peak derived from the curing of the curable component overlaps at least partially.

  Specifically, the above thermosetting component is heated at a rate of temperature increase of 10 ° C./min, and differential scanning calorimetry (DSC) is performed. Further, the conductive particles are heated at a rate of temperature increase of 10 ° C./min, and differential scanning calorimetry (DSC) is performed. This measurement may be performed using a conductive material. As schematically shown in FIG. 1, in this DSC, in the conductive material according to the present invention, the temperature region showing the endothermic peak P3 derived from the melting of the solder in the conductive particles and the curing of the thermosetting component are used. The temperature region showing the exothermic peaks P1 and P2 derived from at least partially overlaps.

  In this invention, since said structure is provided, the solder in electroconductive particle can be selectively arrange | positioned on an electrode. When the electrodes are electrically connected, the solder in the conductive particles easily collects between the upper and lower electrodes, and the solder in the conductive particles can be efficiently disposed on the electrodes (lines). Moreover, it is difficult for the cured product of the thermosetting component to remain between the electrode and the solder part, and the contact area between the electrode and the solder part can be increased.

  In addition, a part of the solder in the conductive particles is difficult to be disposed in a region (space) where no electrode is formed, and the amount of solder disposed in a region where no electrode is formed can be considerably reduced. In the present invention, the solder that is not located between the opposing electrodes can be efficiently moved between the opposing electrodes. Therefore, the conduction reliability between the electrodes can be improved. In addition, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, and to improve insulation reliability.

  As shown in FIG. 1, the total calorific value (1) derived from the curing of the thermosetting component in the temperature region below the endothermic peak top P3t temperature derived from the melting of the solder in the conductive particles is the conductivity. It is preferable to be smaller than the total calorific value (2) derived from the curing of the thermosetting component in the temperature range equal to or higher than the endothermic peak top P3t temperature derived from melting of the solder in the particles. The total calorific value (1) is preferably 1/2 or less, more preferably 1/5 or less of the total calorific value (2). Since the total calorific value (1) is relatively small, the thickness of the conductive material can be sufficiently secured before the solder is melted, and the positions of the plurality of conductive particles can be brought close to each other. It can be moved further on the electrode. In particular, when mounting on the surface of a semiconductor chip or the like, resin flow occurs from the central part to the outer peripheral part, so that a difference in the amount of solder on the electrode between the central part and the outer peripheral part tends to occur. By adjusting the total calorific value derived from the curing of the solder within the above range, it becomes possible to uniformly mount the solder amount on the electrode at the center and the outer periphery, and effectively reduce the variation in the amount of solder on the electrode Can be suppressed. Since the total calorific value (2) is relatively large, after the solder is melted, the solder disposed on the electrode can be retained on the electrode, and the amount of solder on the electrode can be further increased.

  As shown in FIG. 1, there is a first exothermic peak top P1t temperature derived from the curing of the thermosetting component on the lower temperature side than the endothermic peak top P3t temperature derived from the melting of the solder in the conductive particles, In addition, it is preferable that there is a second exothermic peak top P2t temperature derived from the curing of the thermosetting component on the higher temperature side than the endothermic peak top P3t temperature derived from the melting of the solder in the conductive particles. In this case, the position of the plurality of conductive particles can be brought closer, and the solder melts quickly after the position of the plurality of conductive particles approaches, and as a result, the plurality of conductive particles move further on the electrode. Can be made.

  The absolute value of the difference between the endothermic peak top P3t temperature and the first exothermic peak top P1t temperature is preferably 3 ° C or higher, more preferably 5 ° C or higher, still more preferably 8 ° C or higher, preferably 60 ° C or lower. More preferably, it is 58 degrees C or less, More preferably, it is 55 degrees C or less. In this case, the position of the plurality of conductive particles can be brought closer, and the solder melts quickly after the position of the plurality of conductive particles approaches, and as a result, the plurality of conductive particles move further on the electrode. Can be made.

  The absolute value of the difference between the endothermic peak top P3t temperature and the second exothermic peak top P2t temperature is preferably 5 ° C or higher, more preferably 8 ° C or higher, still more preferably 10 ° C or higher, preferably 60 ° C or lower. More preferably, it is 58 degrees C or less, More preferably, it is 55 degrees C or less. In this case, after the molten solder is disposed on the electrode, the solder can be retained on the electrode, and the amount of solder on the electrode can be further increased.

  From the viewpoint of more efficiently arranging the solder on the electrode, as shown in FIG. 1, the peak height of the exothermic peak at the first exothermic peak top P1t temperature is the second exothermic peak top P2t temperature. It is preferable that it is smaller than the peak height of the exothermic peak.

  The exothermic peak top P1t, P2t temperature and the endothermic peak top P3t temperature indicate temperatures at which the exothermic amount or endothermic amount at the exothermic peaks P1, P2 or the endothermic peak P3 is the highest. The exothermic peaks P1 and P2 indicate that the exothermic amount decreases after reaching the exothermic peak tops P1t and P2t from the portion where the exothermic amount starts to increase from the baseline B (the temperature at that portion is the exothermic start temperature), The part until the calorific value starts increasing again or the calorific value reaches the baseline B is shown. The endothermic peak P3 is a portion where the endothermic amount starts to increase from the base line B (the temperature at that portion is the endothermic start temperature), and the endothermic amount decreases after reaching the endothermic peak top P3t. The part up to line B is shown. In order for the exothermic peak top P1t, P2t temperature and the endothermic peak top P3t temperature to satisfy the relationship described above, the type of thermosetting compound in the thermosetting component, the type of thermosetting agent, and What is necessary is just to adjust suitably the composition etc. of the solder in electroconductive particle.

  From the viewpoint of more efficiently arranging the solder on the electrode, the peak end temperature on the high temperature side of the endothermic peak derived from the melting of the solder in the conductive particles is the most derived from the curing of the thermosetting component. It is preferable that the exothermic peak on the high temperature side is lower than the peak end temperature on the high temperature side. The peak end temperature on the high temperature side of the endothermic peak derived from melting of the solder in the conductive particles is a temperature continuous to the base line B on the high temperature side of the endothermic peak P3 in FIG. The peak end temperature on the high temperature side of the highest temperature exothermic peak derived from the curing of the thermosetting component is a temperature continuous to the base line B on the high temperature side of the exothermic peak P2 in FIG.

  From the viewpoint of more efficiently disposing the solder on the electrode, the peak start temperature on the low temperature side of the endothermic peak derived from the melting of the solder in the conductive particles is the most derived from the curing of the thermosetting component. It is preferable that the exothermic peak on the low temperature side is higher than the peak start temperature on the low temperature side. The peak start temperature on the low temperature side of the endothermic peak derived from melting of the solder in the conductive particles is a temperature continuous to the baseline B on the low temperature side of the endothermic peak P3 in FIG. The low-temperature peak start temperature of the lowest-temperature exothermic peak derived from the curing of the thermosetting component is a temperature continuous to the baseline B on the low-temperature side of the exothermic peak P1 in FIG.

  From the viewpoint of more efficiently arranging the solder on the electrode, from the viewpoint of more efficiently arranging the solder on the electrode, the endothermic peak derived from melting of the solder in the conductive particles is on the high temperature side. The peak end temperature is lower than the peak end temperature on the high temperature side of the highest temperature exothermic peak derived from the curing of the thermosetting component, and the endothermic peak derived from melting of the solder in the conductive particles. The peak start temperature on the low temperature side is preferably higher than the peak start temperature on the low temperature side of the lowest heat generation peak derived from the curing of the thermosetting component.

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

  In order to arrange the solder more efficiently on the electrode, the viscosity (η25) at 25 ° C. of the conductive material is preferably 20 Pa · s or more, more preferably 25 Pa · s or more, preferably 600 Pa · s or less. More preferably, it is 550 Pa · s or less. The viscosity at 25 ° C. of the conductive material affects the moving speed of conductive particles or solder at the initial stage of the conductive connection.

  In order to arrange the solder more efficiently on the electrode, the ratio of the viscosity of the conductive material at 25 ° C. (η25) to the viscosity of the conductive material at 100 ° C. (η100) is preferably 10 or more, more preferably 80 or more, more preferably 100 or more, preferably 2500 or less, more preferably 2000 or less. The viscosity at 100 ° C. of the conductive material affects the moving speed of conductive particles or solder in the middle of conductive connection. When the ratio (η25 / η100) is not less than the above lower limit and not more than the above upper limit, the conductive particles or the solder efficiently move from the initial stage to the middle stage at the time of conductive connection.

  The viscosity can be measured using STRESSTECH (manufactured by EOLOGICA) under the conditions of strain control 1 rad, frequency 1 Hz, temperature rising rate 20 ° C./min, and measurement temperature range 25 to 200 ° C.

  The viscosity after holding the conductive material at the exothermic peak top P1t temperature derived from the curing of the thermosetting component for 10 seconds is preferably 1 Pa · s or more, more preferably 3 Pa · s or more, preferably 10 Pa. · S or less, more preferably 8 Pa · s or less. Further, the viscosity after holding the conductive material at the exothermic peak top P2t temperature derived from the curing of the thermosetting component for 10 seconds is preferably 100 Pa · s or more, more preferably 110 Pa · s or more, and preferably 10,000 Pa. · S or less, more preferably 9500 Pa · s 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 preferably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

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

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

  In addition, compared with the case where the above solder particles are used, in the case where conductive particles including base particles not formed by solder and solder portions arranged on the surface of the base particles are used, The conductive particles are less likely to collect on the surface, and the solder joint property between the conductive particles is low, so the conductive particles that have moved onto the electrodes tend to move out of the electrodes, and the effect of suppressing displacement between the electrodes Tend to be lower. Therefore, the conductive particles are preferably solder particles.

  From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, a carboxyl group or an amino group is present on the outer surface of the conductive particles (the outer surface of the solder). It is preferable that a carboxyl group is present, and an amino group is preferably present. A group containing a carboxyl group or an amino group is shared on the outer surface of the conductive particle (the outer surface of the solder) via a Si-O bond, an ether bond, an ester bond, or a group represented by the following formula (X). It is preferably bonded, and more preferably a group containing a carboxyl group or an amino group is covalently bonded through 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 exist on the surface of the solder. By covalently bonding this hydroxyl group and a group containing a carboxyl group, a stronger bond can be formed than in the case of bonding by other coordination bond (chelate coordination) or the like, so the connection resistance between the electrodes is reduced, And the electroconductive particle which can suppress generation | occurrence | production of a void is obtained.

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

  From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, the conductive particle is a compound having a functional group capable of reacting with a hydroxyl group and a carboxyl group or an amino group ( Hereinafter, it 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 in which a group containing a carboxyl group or an amino group is covalently bonded to the surface of the solder are easily obtained. It is also possible to obtain conductive particles in which a group containing a carboxyl group or an amino group is covalently bonded to the surface of the solder via an ether bond or an ester bond. By reacting a hydroxyl group on the surface of the solder with a functional group capable of reacting with the hydroxyl group, the compound X can be chemically bonded to the surface of the solder in the form of a covalent bond.

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

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

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

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

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

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

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

  Examples of the solvent include 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, and more preferably toluene. As for the said solvent, only 1 type may be used and 2 or more types may be used together.

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

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

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

  Moreover, a silane coupling agent can be easily reacted with a group derived from an isocyanate group. Since the conductive particles can be easily obtained, the group containing a carboxyl group is introduced by a reaction using a silane coupling agent having a carboxyl group, or the reaction using a silane coupling agent is performed. It is preferably introduced later by reacting a compound derived from a silane coupling agent with a compound having at least one carboxyl group. The conductive particles are preferably obtained by reacting the isocyanate compound with a hydroxyl group on the surface of the solder using the isocyanate compound and then reacting a compound having at least one carboxyl group.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  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 main body and an anionic polymer disposed on the surface of the conductive particle main body. preferable. The conductive particles are preferably obtained by surface-treating the conductive particle body with an anionic polymer or a compound that becomes an anionic polymer. The conductive particles are preferably a surface treated product of an anionic polymer or a compound that becomes an anionic polymer. As for the said anion polymer and the compound used as the said anion polymer, only 1 type may respectively be used and 2 or more types may be used together. The anionic polymer is a polymer having an acidic group.

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

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

  In addition, as another method for the surface treatment, a compound having a functional group that reacts with a hydroxyl group on the surface of the conductive particle main body and a functional group that can be polymerized by addition or condensation reaction is used. The method of polymerizing on the surface of an electroconductive particle main body is mentioned. 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, and the functional group that polymerizes by addition and condensation reactions includes a hydroxyl group, a carboxyl group, an amino group, and (meta ) An acryloyl group is mentioned.

  The weight average molecular weight of the anionic polymer is preferably 2000 or more, more preferably 3000 or more, preferably 10,000 or less, more preferably 8000 or less. When the weight average molecular weight is not less than the above lower limit and not more than the above upper limit, a sufficient amount of charge and flux properties can be introduced on the surface of the conductive particles. Thereby, the cohesiveness of electroconductive particle can be effectively improved at the time of conductive connection, and the oxide film on the surface of an electrode can be effectively removed at the time of connection of the connection object member.

  When the weight average molecular weight is not less than the above lower limit and not more than the above upper limit, it is easy to dispose an anionic polymer on the surface of the conductive particle body, and it is possible to effectively increase the cohesiveness of the solder particles at the time of conductive connection. In addition, the conductive particles can be arranged more efficiently 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 measured by dissolving the solder in the conductive particles, removing the conductive particles with dilute hydrochloric acid 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.

  Regarding the introduction amount of the anionic polymer 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 conductive particles is added to 36 g of acetone and dispersed with an ultrasonic wave for 1 minute. Thereafter, phenolphthalein is used as an indicator and titrated with a 0.1 mol / L potassium hydroxide ethanol solution.

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

  FIG. 5 is a cross-sectional view showing a first example of conductive particles that can be used as a conductive material.

  The conductive particles 21 shown in FIG. 5 are solder particles. The conductive particles 21 are entirely formed of solder. The conductive particles 21 do not have base particles in the core, and are not core-shell particles. As for the electroconductive particle 21, both the center part and the outer surface part of an electroconductive part are formed with the solder.

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

  The conductive particles 31 shown in FIG. 6 include base particles 32 and conductive portions 33 arranged on the surfaces of the base particles 32. The conductive portion 33 covers the surface of the base particle 32. The conductive particles 31 are coated particles in which the surface of the base particle 32 is covered with the conductive portion 33.

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

  FIG. 7 is a cross-sectional view showing a third example of conductive particles that can be used for the conductive material.

  As described above, the conductive portion 33 in the conductive particle 31 has a two-layer structure. The conductive particle 41 shown in FIG. 7 has a solder part 42 as a single-layer conductive part. The conductive particles 41 include base particles 32 and solder portions 42 disposed on the surfaces of the base particles 32.

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

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

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

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (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, glycidyl (meth) acrylate, etc. Elemental atom-containing (meth) acrylate compounds; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; acids such as vinyl acetate, vinyl butyrate, vinyl laurate, 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 Etc.

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

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

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

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

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

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

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

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

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

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

  The solder is preferably a metal (low melting point metal) having a melting point of 450 ° C. or lower. The solder part is preferably a metal layer (low melting point metal layer) having a melting point of 450 ° C. or lower. The low melting point metal layer is a layer containing a low melting point metal. The solder in the conductive particles is preferably metal particles having a melting point of 450 ° C. or lower (low melting point metal particles). The low melting point metal particles are particles containing a low melting point metal. The low melting point metal is a metal having a melting point of 450 ° C. or lower. The melting point of the low melting point metal is preferably 300 ° C. or lower, more preferably 160 ° C. or lower. The solder in the conductive particles preferably contains tin. In 100% by weight of the metal contained in the solder part and 100% by weight of the metal contained in the solder in the conductive particles, the content of tin is preferably 30% by weight or more, more preferably 40% by weight or more, and still more preferably. It is 70% by weight or more, particularly preferably 90% by weight or more. When the content of tin contained in the solder in the conductive particles is not less than the above lower limit, the conduction reliability between the conductive particles and the electrode is further enhanced.

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

  By using the conductive particles having the solder on the outer surface portion of the conductive portion, the solder is melted and joined to the electrodes, and the solder conducts between the electrodes. For example, since the solder and the electrode are not in point contact but in surface contact, the connection resistance is lowered. In addition, the use of conductive particles having solder on the outer surface of the conductive portion increases the bonding strength between the solder and the electrode, and as a result, the solder and the electrode are more unlikely to peel off, and the conduction reliability is effective. To be high.

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

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

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

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

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

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

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

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

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

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

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

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

(Thermosetting compound)
The thermosetting compound is a compound that can be cured by heating. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. From the viewpoint of further improving the curability and viscosity of the conductive material and further improving the connection reliability, an epoxy compound or an episulfide compound is preferable, and an epoxy compound is more preferable. The conductive material preferably contains an epoxy compound. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further suppressing the corrosion of the electrode and maintaining the connection resistance even lower, the thermosetting compound preferably includes a thermosetting compound having a nitrogen atom, and a thermosetting compound having a triazine skeleton is used. It is preferable to include.

  Examples of the thermosetting compound having a nitrogen atom 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, TEPIC-UC) and the like.

  An aromatic epoxy compound is mentioned as said epoxy compound. Crystalline epoxy compounds such as resorcinol type epoxy compounds, naphthalene type epoxy compounds, biphenyl type epoxy compounds, and benzophenone type epoxy compounds are preferred. An epoxy compound that is solid at normal temperature (23 ° C.) and has a melting temperature not higher than the melting point of the solder is preferable. The melting temperature is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and preferably 40 ° C. or higher. By using the above-mentioned preferable epoxy compound, the first connection target member and the second connection are high when the connection target member is pasted and when the viscosity is high and acceleration is applied by impact such as conveyance. The positional deviation 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 proceed efficiently.

  The content of the thermosetting compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight or less. More preferably, it is 98 weight% or less, More preferably, it is 90 weight% or less, Most preferably, it is 80 weight% or less. When the content of the thermosetting compound is not less than the above lower limit and not more than the above upper limit, the solder in the conductive particles can be more efficiently arranged on the electrodes, and the displacement between the electrodes can be further suppressed, The conduction reliability can be further improved. From the viewpoint of further improving the impact resistance, it is preferable that the content of the thermosetting compound is large. 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 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 15%. % By weight or more, preferably 50% by weight or less, more preferably 30% by weight or less.

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

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

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

  The solubility parameter of the thiol curing agent is preferably 9.5 or more, and 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]. Examples include undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine, and diaminodiphenylsulfone.

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

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

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

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

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

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

(flux)
The conductive material preferably contains a flux. By using flux, the solder can be more effectively placed on the electrode. The flux is not particularly limited. As the flux, a flux generally used for soldering or the like can be used. The conductive material may not contain flux.

  Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an organic acid, and pine resin. Etc. As for the said flux, only 1 type may be used and 2 or more types may be used together.

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

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

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

  The flux having an active temperature (melting point) of 80 ° C. or higher and 190 ° C. or lower includes succinic acid (melting point 186 ° C.), glutaric acid (melting point 96 ° C.), adipic acid (melting point 152 ° C.), pimelic acid (melting point) 104 ° C.), dicarboxylic acids such as suberic acid (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), malic acid (melting point 130 ° C.) and the like.

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

  From the viewpoint of more efficiently arranging the solder 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 5 ° C or higher, and more preferably 10 ° C or higher. More preferably.

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

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

  When the melting point of the flux is higher than the melting point of the solder, the solder can be efficiently aggregated on the electrode portion. This is because, when heat is applied at the time of joining, when the electrode formed on the connection target member is compared with the portion of the connection target member around the electrode, the thermal conductivity of the electrode portion is Due to the fact that it is higher than the thermal conductivity, the temperature rise of the electrode portion is fast. At the stage where the melting point of the solder in the conductive particles is exceeded, the solder in the conductive particles dissolves, but the oxide film formed on the surface does not reach the melting point (activation temperature) of the flux and is not removed. In this state, since the temperature of the electrode part first reaches the melting point (activation temperature) of the flux, the oxide film on the surface of the solder on the conductive particles preferentially coming on the electrode is removed or activated. Since the electric charge on the surface of the solder in the conductive particles is neutralized by the flux, the solder can spread on the surface of the electrode. Thereby, a solder can be efficiently aggregated on an electrode.

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

  Examples of the flux that releases cations by the heating include the thermal cation initiator.

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

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

(Connection structure and method of manufacturing connection structure)
A connection structure according to the present invention includes a first connection target member having at least one first electrode on the surface, a second connection target member having at least one second electrode on the surface, and the first The connection object member and the connection part which has connected the said 2nd connection object member are provided. In the connection structure according to the present invention, the material of the connection part is the conductive material described above, and the connection part is a cured product of the conductive material described above. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

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

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

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

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

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

  Furthermore, in the step of arranging the second connection target member and the step of forming the connection portion, if the weight of the second connection target member is added to the conductive material without applying pressure, the connection portion is Solder arranged in a region (space) where no electrode is formed before it is formed is more likely to gather between the first electrode and the second electrode, and solder in a plurality of conductive particles can be It has also been found that it can be arranged more efficiently on the line). In the present invention, a configuration in which a conductive paste is used instead of a conductive film and a configuration in which the weight of the second connection target member is added to the conductive paste without applying pressure are used in combination. This has a great meaning in order to obtain the effects of the present invention at a higher level.

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

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

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

  FIG. 2 is a cross-sectional view schematically showing a connection structure obtained using a conductive material according to an embodiment of the present invention.

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

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

  The first connection target member 2 has a plurality of first electrodes 2a on the surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by the solder portion 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by the solder portion 4A. In the connection portion 4, no solder exists in a region (cured product portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In an area different from the solder part 4A (hardened product part 4B part), there is no solder separated from the solder part 4A. If the amount is small, the solder may be present in a region (cured product portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a.

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

  Note that the conductive material may contain a flux. When the flux is used, the flux is generally deactivated gradually by heating.

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

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

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

  From the viewpoint of further improving the conduction reliability, the portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode is seen. When the ratio of the area where the solder portion in the connecting portion is arranged in the area of the area where the first electrode and the second electrode face each other is 100%, the area at the center electrode Is preferably less than 15%, more preferably less than 10%, and even more preferably less than 5%.

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

  First, the 1st connection object member 2 which has the 1st electrode 2a on the surface (upper surface) is prepared. Next, as shown to Fig.3 (a), the electrically conductive material 11 containing the thermosetting component 11B and the several solder particle 11A is arrange | positioned on the surface of the 1st connection object member 2 (1st Process). The used conductive material 11 contains a thermosetting compound and a thermosetting agent as the thermosetting component 11B.

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

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

  Moreover, the 2nd connection object member 3 which has the 2nd electrode 3a on the surface (lower surface) is prepared. Next, as shown in FIG.3 (b), in the conductive material 11 on the surface of the 1st connection object member 2, on the surface on the opposite side to the 1st connection object member 2 side of the conductive material 11, The 2nd connection object member 3 is arrange | positioned (2nd process). On the surface of the conductive material 11, the second connection target member 3 is disposed from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

  Next, the conductive material 11 is heated above the melting point of the solder particles 11A (third step). Preferably, the conductive material 11 is heated above the curing temperature of the thermosetting component 11B (binder). At the time of this heating, the solder particles 11A that existed in the region where no electrode is formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). When the conductive paste is used instead of the conductive film, the solder particles 11A are effectively collected between the first electrode 2a and the second electrode 3a. Also, the solder particles 11A are melted and joined together. Further, the thermosetting component 11B is thermoset. As a result, as shown in FIG. 3C, the connection portion 4 that connects the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. The connection part 4 is formed of the conductive material 11, the solder part 4A is formed by joining a plurality of solder particles 11A, and the cured part 4B is formed by thermosetting the thermosetting component 11B.

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

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

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

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

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

  The said 1st, 2nd connection object member is not specifically limited. Specifically as said 1st, 2nd connection object member, electronic components, such as a semiconductor chip, a semiconductor package, LED chip, LED package, a capacitor | condenser, a diode, and a resin film, a printed circuit board, a flexible printed circuit board, flexible Examples include electronic components such as flat cables, rigid flexible substrates, glass epoxy substrates, and circuit boards such as glass substrates. The first and second connection target members are preferably electronic components.

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

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

  Examples of the electrode provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, a SUS electrode, and a tungsten electrode. When the connection object member is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient and the electrode by which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the material for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

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

Polymer A:
Synthesis of reaction product (polymer A) of bisphenol F with 1,6-hexanediol diglycidyl ether and bisphenol F type epoxy resin:
72 parts by weight of bisphenol F (containing 4,4′-methylene bisphenol, 2,4′-methylene bisphenol and 2,2′-methylene bisphenol in a weight ratio of 2: 3: 1), 1,6-hexanediol 70 parts by weight of glycidyl ether and 30 parts by weight of a bisphenol F type epoxy resin (“EPICLON EXA-830CRP” manufactured by DIC) were placed in a three-necked flask and dissolved at 150 ° C. under a nitrogen flow. Thereafter, 0.1 part by weight of tetra-n-butylsulfonium bromide, which is an addition reaction catalyst between a hydroxyl group and an epoxy group, was added, and an addition polymerization reaction was performed at 150 ° C. for 6 hours under a nitrogen flow. A) was obtained.

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

  The reaction product (polymer A) obtained by GPC had a weight average molecular weight of 10,000 and a number average molecular weight of 3,500.

Thermosetting compound 1: Resorcinol type epoxy compound, “EX-201” manufactured by Nagase ChemteX Corporation
Thermosetting agent 1: Thiol thermosetting agent, "Karenz MT" manufactured by Showa Denko KK
Thermosetting agent 2: Microcapsule type thermosetting agent, “HXA3922HP” manufactured by Asahi Kasei E-Materials
Latent thermosetting agent 1: “Fujicure 7000” manufactured by T & K TOKA
Flux 1: Glutaric acid, Wako Pure Chemical Industries Co., Ltd. Coupling agent 1: Silane coupling agent, Shin-Etsu Silicone “KBE-9007”
Solder particles 1:
Method for producing solder particles 1:
SnBi solder particles (“ST-5” manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter (median diameter) 5 μm) and glutaric acid (a compound having two carboxyl groups, “glutaric acid” manufactured by Wako Pure Chemical Industries, Ltd.) By using p-toluenesulfonic acid as a catalyst and stirring for 8 hours while dehydrating in a toluene solvent at 90 ° C., solder particles 1 in which a carboxyl group-containing group is covalently bonded to the surface of the solder were obtained.

  In the obtained solder particles 1, the CV value was 20%, and the molecular weight Mw of the polymer constituting the surface was 2000.

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

(2) Production of First Connection Structure (Area Array Substrate) As a first connection target member, a 250 μm copper electrode with a pitch of 400 μm is provided on the surface of a semiconductor chip body (size 5 × 5 mm, thickness 0.4 mm). A semiconductor chip was prepared, which is arranged in an area array and has a passivation film (polyimide, thickness 5 μm, opening diameter of electrode part 200 μm) formed on the outermost surface. The number of copper electrodes is 10 × 10 in total per 100 semiconductor chips.

  As the second connection target member, the same pattern is formed on the surface of the glass epoxy substrate main body (size 20 × 20 mm, thickness 1.2 mm, material FR-4) with respect to the electrode of the first connection target member. The glass epoxy board | substrate with which the copper resist is arrange | positioned and the soldering resist film is formed in the area | region where the copper electrode is not arrange | positioned was prepared. The level difference 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 fabrication was applied to the upper surface of the glass epoxy substrate with a dispenser to form an anisotropic conductive paste layer. The method of applying the anisotropic conductive paste layer was performed so that the diameter was 2.5 mm at the center of the glass epoxy substrate. Next, the semiconductor chip was stacked on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other. The weight of the semiconductor chip is added to the anisotropic conductive paste layer.

  Heating was performed so that the temperature of the anisotropic conductive paste layer became 139 ° C. (melting point of solder) after 5 seconds from the start of temperature increase. Further, 15 seconds after the start of temperature increase, the anisotropic conductive paste layer was heated to 160 ° C. to cure the anisotropic conductive paste, and a connection structure was obtained. No pressure was applied during heating.

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

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

  An anisotropic conductive paste immediately after fabrication was applied to the upper surface of the glass epoxy substrate with a dispenser to form an anisotropic conductive paste layer. The method of applying the anisotropic conductive paste layer was performed so that the diameter was 2.5 mm at the center of the glass epoxy substrate. Next, the semiconductor chip was stacked on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other. The weight of the semiconductor chip is added to the anisotropic conductive paste layer.

  Heating was performed so that the temperature of the anisotropic conductive paste layer became 139 ° C. (melting point of solder) after 5 seconds from the start of temperature increase. Further, 15 seconds after the start of temperature increase, the anisotropic conductive paste layer was heated to 160 ° C. to cure the anisotropic conductive paste, and a connection structure was obtained. No pressure was applied during heating.

(Evaluation)
(1) Viscosity Viscosity (η25) at 25 ° C. and viscosity (η100) at 100 ° C. of an anisotropic conductive paste using STRESSTECH (manufactured by EOLOGICA), strain control 1 rad, frequency 1 Hz, heating rate The measurement was performed under the conditions of 20 ° C./min and a measurement temperature range of 25 to 200 ° C.

(2) Measurement of exothermic peak P1 and endothermic peak P2 by DSC The thermosetting components in the anisotropic conductive pastes of Examples and Comparative Examples were blended. By using a differential scanning calorimeter (“Q2000” manufactured by TA Instruments), the obtained thermosetting component is heated at a rate of temperature increase of 10 ° C./min. The exothermic peaks P1 and P2 were measured.

  Further, using a differential scanning calorimeter (“Q2000” manufactured by TA Instruments), the conductive particles are heated at a temperature rising rate of 10 ° C./min, and the endotherm resulting from melting of the solder in the conductive particles. Peak P3 was measured.

  Table 1 below shows the results of the following 1) to 9).

1) Presence / absence of overlap between the temperature region showing the endothermic peak P3 derived from melting of the solder in the conductive particles and the temperature region showing the exothermic peak P1 derived from curing of the thermosetting component 2) The solder in the conductive particles Presence / absence of overlap between the temperature region showing the endothermic peak P3 derived from melting and the temperature region showing the exothermic peak P2 derived from the curing of the thermosetting component 3) Exothermic peak top P1t temperature derived from the curing of the thermosetting component 4) Exothermic peak top P2t temperature derived from curing of thermosetting component 5) Endothermic peak top P3t temperature derived from melting of solder in conductive particles 6) Difference between endothermic peak top P3t temperature and exothermic peak top P1t temperature Absolute value 7) Absolute value of difference between endothermic peak top P3t temperature and exothermic peak top P2t temperature 8) Temperature below endothermic peak top P3t temperature Total calorific value derived from curing of thermosetting components in the region (low temperature side)
9) Total calorific value (high temperature side) derived from the curing of the thermosetting component in the temperature range above the endothermic peak top P3t temperature.

  Table 1 below also shows the results of the following 10) and 11).

  10) The peak end temperature (X1) on the high temperature side of the endothermic peak derived from melting of the solder in the conductive particles and the peak end temperature on the high temperature side of the highest exothermic peak derived from curing of the thermosetting component Relationship with (Y1); described in Table 1 as X1 <Y1, X1 = Y1 or X1> Y1.

  11) Low-temperature-side peak start temperature (X2) of the endothermic peak derived from melting of the solder in the conductive particles and low-temperature-side peak start temperature of the lowest-temperature exothermic peak derived from curing of the thermosetting component Relationship with (Y2); described in Table 1 as X2 <Y2, X2 = Y2 or X2> Y2.

  In the evaluations 1) and 2) above, “−” shown as a result indicates that no peak exists. In the evaluations of 10) and 11) above, “−” shown as a result indicates that evaluation is not performed.

(3) Solder placement accuracy on electrode 1
In the obtained connection structure, when a portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode at the center, the connection portion, and the second electrode is viewed, The ratio X of the area where the solder part in the connection part is arranged in 100% of the area of the part where the electrode and the second electrode face each other was evaluated. The solder placement accuracy 1 on the electrode was determined according to the following criteria.

[Criteria for solder placement accuracy 1 on electrode]
◯: Ratio X is 90% or more ○: 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) Solder placement accuracy on electrode 2
In the obtained connection structure, when a portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode on the outer peripheral portion is viewed, The ratio Y of the solder part in the connection part arrange | positioned in the part which the 1st electrode and 2nd electrode oppose in 100% of solder parts in the inside was evaluated. The solder placement accuracy 2 on the electrode was determined according to the following criteria.

[Criteria for solder placement accuracy 2 on electrode]
◯: Ratio X is 90% or more ○: 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%

(5) Solder placement accuracy in the board 3
In the obtained connection structure, when the portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode is viewed, Regarding the ratio of the area where the solder part in the connection part is arranged in the area of the area facing the second electrode 100%, the ratio of the area at the center electrode and the area at the outer peripheral electrode The difference Z from the ratio was evaluated. The solder placement accuracy 3 in the substrate was determined according to the following criteria.

[Criteria for solder placement accuracy 3 on the board]
○: Difference Z is less than 5% ○: Difference Z is 5% or more and less than 10% Δ: Difference Z is 10% or more and less than 15% ×: Difference Z is 15% or more

(6) Electrical connection reliability between upper and lower electrodes In the obtained connection structure (n = 15), the connection resistance between the upper and lower electrodes was measured by a four-terminal method. The average value of connection resistance was calculated. Note that the connection resistance can be obtained by measuring the voltage when a constant current is passed from the relationship of voltage = current × resistance. The conduction reliability was determined according to the following criteria.

[Judgment criteria for conduction reliability]
○○: Average value of connection resistance is 8.0Ω or less ○: Average value of connection resistance exceeds 8.0Ω and 10.0Ω or less △: Average value of connection resistance exceeds 10.0Ω and 15.0Ω or less × : Average connection resistance exceeds 15.0Ω

  The results are shown in Table 1 below.

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

DESCRIPTION OF SYMBOLS 1,1X ... Connection structure 2 ... 1st connection object member 2a ... 1st electrode 3 ... 2nd connection object member 3a ... 2nd electrode 4, 4X ... Connection part 4A, 4XA ... Solder part 4B, 4XB ... Cured part 11 ... Conductive material 11A ... Solder particles (conductive particles)
11B ... thermosetting component 21 ... conductive particles (solder particles)
31 ... Conductive particles 32 ... Base particle 33 ... Conductive part (conductive part having solder)
33A ... second conductive part 33B ... solder part 41 ... conductive particles 42 ... solder part

Claims (11)

A plurality of conductive particles having solder on the outer surface portion of the conductive portion, and a thermosetting component,
When the differential scanning calorimetry is performed by heating the conductive particles and the thermosetting component at a temperature rising rate of 25 ° C. to 10 ° C./min, respectively, it is derived from melting of the solder in the conductive particles. A conductive material in which a temperature region showing an endothermic peak and a temperature region showing an exothermic peak derived from curing of the thermosetting component overlap at least partially.   Endothermic peak top derived from the melting of the solder in the conductive particles is the total calorific value derived from the curing of the thermosetting component in the temperature region below the endothermic peak top temperature derived from the melting of the solder in the conductive particles. The conductive material according to claim 1, wherein the conductive material is smaller than a total calorific value derived from curing of the thermosetting component in a temperature region equal to or higher than a temperature.   There is a first exothermic peak top temperature derived from the curing of the thermosetting component on a lower temperature side than the endothermic peak top temperature derived from melting of the solder in the conductive particles, and the solder in the conductive particles The conductive material according to claim 1 or 2, wherein there is a second exothermic peak top temperature derived from curing of the thermosetting component on a higher temperature side than the endothermic peak top temperature derived from melting.   The absolute value of the difference between the endothermic peak top temperature and the first exothermic peak top temperature is 3 ° C. or more and 60 ° C. or less, and the difference between the endothermic peak top temperature and the second exothermic peak top temperature The conductive material according to claim 3, wherein the absolute value of is 5 ° C. or more and 60 ° C. or less.   The conductive material according to claim 1, wherein a peak end temperature on the high temperature side of the endothermic peak is lower than a peak end temperature on the high temperature side of the exothermic peak on the highest temperature side.   The peak end temperature on the high temperature side of the endothermic peak is lower than the peak end temperature on the high temperature side of the exothermic peak on the highest temperature side, and the peak start temperature on the low temperature side of the endothermic peak is the lowest temperature side. The conductive material according to claim 1, wherein the exothermic peak is higher than a low-temperature peak start temperature.   The conductive material according to claim 1, wherein the conductive particles are solder particles.   The conductive material according to claim 1, wherein a carboxyl group is present on the outer surface of the conductive particles.   The conductive material according to claim 1, which is liquid at 25 ° C. and is a conductive paste. A first connection target member having at least one first electrode on its surface;
A second connection target member having at least one second electrode on its surface;
A connection portion connecting the first connection target member and the second connection target member;
The connection part is a cured product of the conductive material according to any one of claims 1 to 9,
A connection structure in which the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.   When the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode 11. The connection structure according to claim 10, wherein a solder portion in the connection portion is disposed in 50% or more of an area of 100% of a portion facing the two electrodes.

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