JP2016004971A - Connection structure and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure that can enhance the resistance-to-bending property even when electrodes of a resin film, a flexible print board or a flexible flat cable are electrically connected, and the reliability of electrical connection between electrodes.SOLUTION: A connection structure has a first connection target member having a first electrode on the surface thereof, a second connection target having a second electrode on the surface thereof, a connection portion for connecting the first connection target member and the second connection target member, and a reinforcing member. The second connection target member is a resin film, a flexible print board or a flexible flat cable. The connection portion is formed of an electrical conduction material which has solder on the electrically conductive outer surface and contains plural electrically conductive particles. In a predetermined area, the reinforcing member is disposed on the surface opposite to the first connection target member side of the second connection target member.

Description

  The present invention relates to a connection structure in which electrodes of a resin film, a flexible printed circuit board, or a flexible flat cable are electrically connected, and a method for manufacturing the connection structure.

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

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

  In particular, a connection structure in which a relatively flexible member such as a flexible printed circuit board and a member such as a rigid substrate (a substrate that does not have flexibility) are connected by an anisotropic conductive material is used for various applications. It has been.

  For example, when the electrode of the flexible printed board and the electrode of the rigid board are electrically connected with the anisotropic conductive material, an anisotropic conductive material containing conductive particles is disposed on the rigid board. 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.

  An example of such a connection structure is disclosed in Patent Document 1 below. The following Patent Document 1 discloses a wiring board connection method for connecting a flexible substrate having flexibility and a flexible substrate including a flexible substrate, flexible wiring, and a coverlay, and a rigid substrate using an anisotropic conductive paste. Is disclosed. This wiring substrate connection method includes an application step of applying the anisotropic conductive paste on the rigid substrate, and a thermocompression bonding step of thermocompression bonding the flexible substrate to the rigid substrate. In the thermocompression bonding step, there is an overlapping region where the rigid substrate and the coverlay overlap in plan view, and the length dimension from the end of the rigid substrate to the end of the coverlay in the overlapping region The flexible substrate is arranged on the anisotropic conductive paste so that the thickness becomes 0.3 mm or more. The heater is brought into contact with the flexible substrate so that the portion in contact with the heater in plan view does not overlap with the coverlay.

JP 2013-51352 A

  In the manufacturing method of the conventional connection structure as described in Patent Document 1, the electrodes of relatively flexible members such as a flexible printed circuit board are electrically connected, which is caused by the flexibility of these connection target members. And there exists a problem that the bending resistance of the connection structure obtained becomes low. Moreover, there exists a problem that the conduction | electrical_connection reliability between electrodes becomes low resulting from the softness | flexibility of a connection object member.

  The object of the present invention is to increase the resistance to bending and improve the conduction reliability between the electrodes even though the electrodes of the resin film, flexible printed circuit board or flexible flat cable are electrically connected. It is to provide a manufacturing method of a structure and a connection structure.

  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 connecting portion connecting the first connection target member and the second connection target member in a state where the second electrode and the second electrode face each other, and a reinforcing member, The connection target member is a resin film, a flexible printed circuit board or a flexible flat cable, and the connection part is formed of a conductive material including a plurality of conductive particles having a solder on a conductive outer surface and a binder resin. The first electrode and the second electrode are electrically connected by the solder in the conductive particles, and the second connection target member is connected to the first connection via the connection portion. versus In the region facing the first connection target member of the second connection target member, the reinforcing member is the first of the second connection target member. A connection structure is provided which is disposed on the surface opposite to the connection target member side.

  It is preferable that the Young's modulus of the reinforcing member is higher than the Young's modulus of the second connection target member. It is preferable that the Young's modulus of the first connection target member is higher than the Young's modulus of the second connection target member. The thickness of the reinforcing member is preferably 100 μm or more and 1000 μm or less.

  In a specific aspect of the connection structure according to the present invention, the second connection target member has a region that does not face the first connection target member.

  In a specific aspect of the connection structure according to the present invention, a coverlay is disposed on the second electrode in a region of the second connection target member that is not opposed to the first connection target member. Yes.

  On the specific situation with the connection structure which concerns on this invention, a said 1st connection object member has an area | region which is not facing the said 2nd connection object member.

  In a specific aspect of the connection structure according to the present invention, the first electrode of the first connection target member in a region of the first connection target member that is not opposed to the second connection target member. A solder resist film is disposed on the top.

  In a specific aspect of the connection structure according to the present invention, the reinforcing member is not opaque so that the position of the second electrode can be confirmed when the second electrode is viewed from the reinforcing member side. Absent.

  On the specific situation with the connection structure which concerns on this invention, the said electroconductive particle is a solder particle.

  According to a wide aspect of the present invention, there is provided a method for manufacturing a connection structure as described above, wherein a first connection target member having at least one first electrode on the surface and at least one second electrode on the surface. A second connection target member, a plurality of conductive particles having solder on a conductive outer surface, and a conductive material including a binder resin, and a reinforcing member, wherein the second connection target member is a resin A film, a flexible printed circuit board, or a flexible flat cable, and a step of disposing a conductive material layer on the surface of the first connection target member using the conductive material; and the first electrode and the second electrode And arranging the second connection target member on the surface of the conductive material layer opposite to the first connection target member so that the first connection target is formed by the conductive material layer. Target Forming a connection part connecting the material and the second connection object member, and the first electrode and the second electrode are electrically connected by the solder in the conductive particles A step of obtaining a structure, wherein the second connection target member has a region facing the first connection target member via the connection portion, and the second connection target member In a region facing the first connection target member, the connection member is disposed on the surface of the second connection target member opposite to the first connection target member side. A method for manufacturing a connection structure is provided.

  In a specific aspect of the manufacturing method of the connection structure according to the present invention, the reinforcing member is disposed in a state where the reinforcing member is disposed on the surface of the second connection target member before being disposed on the surface of the conductive material. The second connection object member is disposed on the surface of the conductive material layer.

  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 A connecting portion connecting the first connection target member and the second connection target member in a state where the second electrode and the second electrode face each other, and a reinforcing member, The connection target member is a resin film, a flexible printed circuit board, or a flexible flat cable, and the connection portion is formed of a conductive material including a plurality of conductive particles having a solder on a conductive outer surface, and a binder resin. The first electrode and the second electrode are electrically connected by the solder in the conductive particles, and the second connection target member is connected to the first connection via the connection portion. versus In the area | region which has the area | region which opposes a member and opposes the said 1st connection object member of the said 2nd connection object member, the said reinforcement member is the said connection part of the said 2nd connection object member Since it is arranged on the surface opposite to the side, it is highly resistant to bending even though the electrodes of the resin film, flexible printed circuit board or flexible flat cable are electrically connected, and conduction between the electrodes Reliability can be increased.

FIG. 1 is a partially cutaway front sectional view schematically showing a connection structure according to an embodiment of the present invention. 2A to 2C are cross-sectional views for explaining each step of the method for manufacturing a connection structure that can obtain the connection structure shown in FIG. FIG. 3 is a cross-sectional view showing a first example of conductive particles that can be used as a conductive material. FIG. 4 is a cross-sectional view showing a second example of conductive particles that can be used for the conductive material. FIG. 5 is a cross-sectional view showing a third example of conductive particles that can be used for the conductive material.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a partially cutaway front sectional view schematically showing a connection structure according to an embodiment of the present invention.

  A connection structure 1 shown in FIG. 1 includes a first connection target member 2, a second connection target member 3, a connection portion 4, and a reinforcing member 5. The first connection target member 2 has at least one first electrode 2a on the surface (upper surface). The second connection target member 3 has at least one second electrode 3a on the surface (lower surface). In the connection structure 1, the first electrode 2a and the second electrode 3a are arranged facing each other.

  The connection portion 4 includes a plurality of conductive particles 21 having solder on a conductive outer surface (not shown in FIG. 1 and FIGS. 2A to 2C and will be described later with reference to FIG. 3), a binder resin And a conductive material including The connection portion 4 connects the first connection target member 2 and the second connection target member 3 with the first electrode 2a and the second electrode 3a facing each other. The connection portion 4 includes a solder portion where the solder in the conductive particles 21 is bonded to each other, and a thermosetting product of the binder resin obtained by thermosetting the binder resin.

  The first electrode 2 a and the second electrode 3 a are electrically connected by solder (solder part) in the conductive particles 21. Note that the conductive particles 21 in the conductive material are gathered between the first electrode 2a and the second electrode 3a. In the present embodiment, the solder in the conductive particles 21 in the conductive material is solidified after being melted, whereby a plurality of conductive particles 21 are collected and the solder is joined to each other to form a solder portion. The solder in the conductive particles 21 is solidified after wetting and spreading on the surfaces of the first and second electrodes 2a and 3a. As a result, as compared with the case where the conductive particles 21 are in the form of intact particles and are in contact with the first and second electrodes 2a and 3a, the solder portion solidified after the solder in the conductive particles 21 is melted is the first. The contact area is increased by being in contact with the second electrodes 2a and 3a. Thus, the conduction | electrical_connection reliability in the connection structure 1 becomes high by using the several electroconductive particle 21 which has a solder on the electroconductive outer surface.

  The 2nd connection object member 3 is a resin film, a flexible printed circuit board, or a flexible flat cable. The second connection target member 3 has flexibility. The second connection target member 3 is relatively flexible.

  The second connection target member 3 has a region R1 that faces the first connection target member 2. In the region R1 of the second connection target member 3 facing the first connection target member 2, the reinforcing member 5 is disposed on the surface opposite to the connection portion 4 side of the second connection target member 3. ing.

  The first connection target member 2 has a region R <b> 2 that does not face the second connection target member 3. The second connection target member 3 has a region R3 that does not face the first connection target member 2.

  In the region R2 of the first connection target member 2 that does not face the second connection target member 3, the solder resist film 6 is disposed on the first electrode 2a. The coverlay 7 is disposed on the second electrode 3a in the region including the region R3 that does not face the first connection target member 2 of the second connection target member 3.

  In the present embodiment, in addition to using the conductive particles 21 having solder on the conductive outer surface, the reinforcing member 5 is different from the connection portion 4 side of the second connection target member 3 in the region R1. Since it arrange | positions on the opposite surface, bending resistance can be made high and the conduction | electrical_connection reliability between electrodes can be improved. Despite being electrically connected to the second electrode 3a of the second connection target member 3 that is a resin film, a flexible printed circuit board, or a flexible flat cable, the bending resistance is increased and the conduction reliability between the electrodes is increased. Can increase the sex. Moreover, when the 2nd connection object member 3 is bend | folded in the X direction shown in FIG. 1, the raise of connection resistance can be suppressed.

  Furthermore, in this embodiment, since the reinforcing member 5 is disposed on the surface opposite to the connection portion 4 side of the second connection target member 3 in the region R1, the first electrode 2a and the second electrode A connection structure with little misalignment with the electrode 3a can be obtained.

  The end of the solder resist film 6 and the end of the second connection target member 3 are spaced apart. The solder resist film 6 and the second connection target member 3 do not face each other.

  In addition, the effect of this invention is acquired because the said reinforcement member is used at the time of the storage after obtaining a connection structure, or obtaining a connection structure. The reinforcing member is preferably used when the connection structure is used. The reinforcing member is preferably bonded to the surface of the second connection target member. However, the reinforcing member may be removed from the surface of the second connection target member when the connection structure is used.

  Examples of the material of the reinforcing member include polyethylene terephthalate and polyimide.

  From the viewpoint of further improving the bending resistance and conduction reliability, the Young's modulus of the reinforcing member is preferably 1 GPa or more, more preferably 1.5 GPa or more. The upper limit of the Young's modulus of the reinforcing member is not particularly limited. The Young's modulus of the reinforcing member may be 3 GPa or less.

  From the viewpoint of further improving the bending resistance and conduction reliability by using the reinforcing member, it is preferable that the Young's modulus of the reinforcing member is higher than the Young's modulus of the second connection target member.

  From the viewpoint of further improving the bending resistance and conduction reliability by using the reinforcing member, the absolute value of the difference between the Young's modulus of the reinforcing member and the Young's modulus of the second connection target member is preferably 0.5 GPa or more. More preferably, it is 1.5 GPa or more. The upper limit of the absolute value of the difference between the Young's modulus of the reinforcing member and the Young's modulus of the second connection target member is not particularly limited. The absolute value of the difference between the Young's modulus of the reinforcing member and the Young's modulus of the second connection target member may be 2.5 GPa or less.

  From the viewpoint of further improving the conduction reliability, it is preferable that the first connection target member does not have flexibility or is a connection target member having lower flexibility than the second connection target member. From the viewpoint of further improving the bending resistance and conduction reliability depending on the arrangement position of the reinforcing member, it is preferable that the Young's modulus of the first connection target member is higher than the Young's modulus of the second connection target member.

  From the viewpoint of further improving the bending resistance and conduction reliability depending on the arrangement position of the reinforcing member, the absolute value of the difference between the Young's modulus of the first connection target member and the second connection target member is preferably Is 0 GPa (for example, in the case of the same member) or more, more preferably 22.5 GPa or more. The upper limit of the absolute value of the difference between the Young's modulus of the first connection target member and the Young's modulus of the second connection target member is not particularly limited. The absolute value of the difference between the Young's modulus of the first connection target member and the Young's modulus of the second connection target member may be 105.5 GPa or less.

  The Young's modulus is measured by a three-point bending method at 23 ° C. using an autograph AGS-X apparatus (manufactured by Shimadzu Corporation).

  From the viewpoint of further improving the bending resistance and conduction reliability, the thickness of the reinforcing member is preferably 100 μm or more, more preferably 200 μm or more. From the viewpoint of suppressing an increase in the size of the connection structure, the thickness of the reinforcing member is preferably 1000 μm or less, more preferably 500 μm or less.

  The second connection target member may have a region that does not face the first connection target member. In this case, the second connection target member has a region located on the side of the side surface of the first connection target member. It is preferable that a coverlay is disposed on the second electrode in a region of the second connection target member that is not opposed to the first connection target member. In this case, the second electrode can be protected, a decrease in connection resistance can be suppressed, and the conduction reliability can be further enhanced.

  The first connection target member may have a region that does not face the second connection target member. In this case, the first connection target member has a region located on the side of the side surface of the second connection target member. It is preferable that a solder resist film is disposed on the first electrode in a region of the first connection target member that is not opposed to the second connection target member. In this case, the first electrode can be protected, a decrease in connection resistance can be suppressed, and the conduction reliability can be further enhanced.

  The reinforcing member may be disposed only in a region of the second connection target member facing the first connection target member, or may extend outside the range of this region. In addition, the reinforcing member may be disposed in an entire region of the second connection target member facing the first connection target member, and the reinforcing member is the second connection target member. It does not need to be arranged in the entire region facing the first connection target member.

  From the viewpoint of further improving the bending resistance and the conduction reliability by using the reinforcing member, from the end of the region of the reinforcing member facing the first connection target member of the second connection target member. The distance protruding to the side is preferably 0.2 mm or more, more preferably 0.5 mm or more.

  From the viewpoint of expressing the flexibility of the second connection target member, from the end of the region of the reinforcing member facing the first connection target member of the second connection target member, laterally. The protruding distance is preferably 2 mm or less, more preferably 0.8 mm or less.

  From the viewpoint of expressing the flexibility of the second connection target member, an end portion of the second connection target member in a region facing the first connection target member of the second connection target member. The distance protruding from the side to the side is preferably 2 mm or less, more preferably 0.8 mm or less.

  It is preferable that the reinforcing member is not opaque so that the position of the second electrode can be confirmed when the second electrode is viewed from the reinforcing member side. In this case, the connection state of the first and second electrodes can be confirmed. Further, when obtaining the connection structure, when the first and second electrodes are aligned in a state where the reinforcing member is disposed on the surface of the second connection target member, the alignment is easily performed. It can be carried out. For this reason, in the connection structure, it is possible to suppress the displacement of the first and second electrodes. By suppressing the displacement of the first and second electrodes, the conduction reliability between the upper and lower electrodes to be connected and the insulation reliability between the laterally adjacent electrodes that should not be connected are further increased. .

  In the connection structure, it is preferable that the connection portion extends to the side of the end portion of the second connection target member. It is preferable that the connection portion reaches between an end portion of the solder resist film and an end portion of the second connection target member.

  The first connection target member is not particularly limited. Specifically as said 1st connection object member, circuits, such as electronic parts, such as a semiconductor chip, a capacitor | condenser, a diode, and a resin film, a printed circuit board, a flexible printed circuit board, a flexible flat cable, a glass epoxy board | substrate, and a glass substrate Examples thereof include electronic parts such as a substrate. The first connection target member is preferably an electronic component.

  Next, each process of the manufacturing method of the connection structure which can obtain the connection structure 1 shown in FIG. 1 is demonstrated, referring FIG. 2 (a)-(c).

  First, the first connection target member 2 having at least the first electrode 2a on the surface (upper surface) is prepared. Moreover, the electroconductive material containing the some electroconductive particle 21 which has a solder on the electroconductive outer surface, and binder resin is prepared. In the present embodiment, the conductive particles 21 are solder particles. In the present embodiment, a thermosetting binder resin is used. In the present embodiment, the solder resist film 6 is disposed on the first electrode 2a in a region of the first connection target member 2 that is not opposed to the second connection target member 3. A coverlay 7 is disposed on the second electrode 3a in a region of the second connection target member 3 that is not opposed to the first connection target member 2.

  As shown in FIG. 2A, the conductive material layer 20 is disposed on the surface of the first connection target member 2 using the conductive material (first step). The conductive material layer 20 is disposed on the surface of the first connection target member 2 on which the first electrode 2a is provided. After the conductive material layer 20 is disposed, the conductive particles 21 are disposed both on the first electrode 2a (line) and on a region (space) where the first electrode 2a is not formed.

  The method for arranging the conductive material is not particularly limited, and examples thereof include application using a dispenser, screen printing, and ejection using an inkjet device. Further, when the conductive material is a conductive film, lamination may be performed in order to dispose the conductive material. Moreover, it is preferable to use a conductive paste.

  In addition, a second connection target member 3 having at least one second electrode 3a on the surface (lower surface) is prepared. In the present embodiment, the reinforcing member 5 is disposed on the surface of the second connection target member 3. Next, as shown in FIG. 2B, in the conductive material layer 20 on the surface of the first connection target member 2, on the surface of the conductive material layer 20 opposite to the first connection target member 2 side. 2nd connection object member 3 is arranged (2nd process). On the surface of the conductive material layer 20, 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. At this time, it is preferable that the end portion of the solder resist film 6 is spaced from the end portion of the second connection target member 3.

  The second connection target member in which the reinforcing member 5 is disposed on the surface in a state where the reinforcing member 5 is disposed on the surface of the second connection target member 3 before being disposed on the surface of the conductive material layer 20. 3 is preferably disposed on the surface of the conductive material layer 20. In this case, a decrease in conduction reliability due to bending when the connection structure is obtained can be further suppressed. Moreover, if the 2nd connection object member 3 in which the reinforcement member 5 is arrange | positioned on the surface is arrange | positioned on the surface of the conductive material layer 20, the conductive material layer 20 is favorable on the surface of the 2nd connection object member 3. As a result, the reliability of conduction is further enhanced.

  Next, the connection part 4 which connects the 1st connection object member 2 and the 2nd connection object member 3 with the electrically-conductive material layer 20 is formed (3rd process). A connection structure 1 is obtained in which the first electrode 2 a and the second electrode 3 a are electrically connected by a solder portion in the conductive particles 21.

  In the third step, it is preferable to heat the conductive material layer 20 to a temperature equal to or higher than the melting point of the solder in the conductive particles 21 and a temperature equal to or higher than the curing temperature of the binder resin having thermosetting properties. That is, it is preferable to heat the conductive material layer 20 to a temperature lower than the melting point of the solder and the curing temperature of the binder resin. During this heating, it is preferable that the conductive particles 21 present in the region where no electrode is formed gather between the first electrode 2a and the second electrode 3a (self-alignment effect). When the conductive paste is used instead of the conductive film, the conductive particles 21 are effectively collected between the first electrode 2a and the second electrode 3a. When solder particles are used as the conductive particles 21, the solder particles are effectively collected between the first electrode 2a and the second electrode 3a. Further, since the conductive particles 21 have solder on the conductive outer surface, the solder is melted by heating and joined to each other. The binder resin is thermoset. As a result, as shown in FIG. 2C, the connection portion 4 that connects the first connection target member 2 and the second connection target member 3 is formed by the conductive material layer 20. The connection part 4 is formed by the conductive material layer 20, the solder part is formed by joining the solder in the plurality of conductive particles 21, and the thermosetting material of the binder resin is formed by thermosetting the thermal binder resin. .

  In addition, a preheating step may be provided in the first half of the third step. This preheating step is a state in which the weight of the second connection object member 3 is added to the conductive material layer 20 at a temperature not lower than the melting temperature of the solder and at a temperature at which the binder resin does not substantially thermoset for 5 seconds. Refers to the process of heating for 60 seconds. By providing this step, the action of collecting the conductive particles between the first electrode and the second electrode is further enhanced, and between the first connection target member and the second connection target member. It is possible to suppress voids that may occur.

  The temperature of the preheating step is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, preferably less than 160 ° C., more preferably 150 ° C. or lower.

  In this way, the connection structure 1 shown in FIG. 1 is obtained. The second step and the third step may be performed continuously. Moreover, after performing the said 2nd process, the laminated body of the obtained 1st connection object member 2, the electrically-conductive material layer 20, and the 2nd connection object member 3 is moved to a heating member, The said 3rd You may perform the process of. In order to perform the heating, the laminate may be disposed on a heating member, or the laminate may be disposed in a heated space.

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

  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 silver electrode, a molybdenum 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, 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, 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.

  The conductive material is, for example, a conductive paste and a conductive film. When the conductive material is a conductive film, a film that does not include conductive particles may be laminated on a conductive film that includes conductive particles. The conductive material is preferably an anisotropic conductive material. From the viewpoint of further improving the conduction reliability, the conductive material is preferably a conductive paste.

  In order to efficiently dispose the conductive particles on the electrode, the viscosity of the conductive paste at 25 ° C. is preferably 10 Pa · s or higher, more preferably 50 Pa · s or higher, more preferably 100 Pa · s or higher, preferably 800 Pa · s or less, more preferably 600 Pa · s or less, and further preferably 500 Pa · s or less.

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

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

  In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably 99.% or more. It is 99 weight% or less, More preferably, it is 99.9 weight% or less. When the content of the binder resin is not less than the above lower limit and not more than the above upper limit, the conductive particles are efficiently arranged between the electrodes, and the conduction reliability of the connection target member connected by the conductive material is further increased.

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 60% by weight or less, more preferably 40% by weight or less, More preferably, it is 20 weight% or less, Most preferably, it is 10 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 conduction reliability between the electrodes is further enhanced.

  Hereinafter, other details of the present invention will be described.

(Conductive particles)
FIG. 3 is a cross-sectional view showing a first example of conductive particles that can be used in the conductive material according to an embodiment of the present invention.

  The conductive particles 21 shown in FIG. 3 are used to obtain the connection structure 1 described above. The conductive particles 21 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 a center part and an outer surface are formed with the solder.

  FIG. 4 is a cross-sectional view showing a second example of conductive particles that can be used in the conductive material according to an embodiment of the present invention.

  The conductive particle 31 shown in FIG. 4 includes a base particle 32 and a conductive layer 33 disposed on the surface of the base particle 32. The conductive layer 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 coated with the conductive layer 33.

  The conductive layer 33 includes a second conductive layer 33A and a solder layer 33B (first conductive layer) disposed on the surface of the second conductive layer 33A. The conductive particle 31 includes a second conductive layer 33A between the base particle 32 and the solder layer 33B. Accordingly, the conductive particles 31 include the base particle 32, the second conductive layer 33A disposed on the surface of the base particle 32, and the solder layer 33B disposed on the surface of the second conductive layer 33A. Is provided. Thus, the conductive layer 33 may have a multilayer structure or may have a stacked structure of two or more layers.

  FIG. 5 is a cross-sectional view showing a third example of conductive particles that can be used in the conductive material according to an embodiment of the present invention.

  As described above, the conductive layer 33 in the conductive particles 31 has a two-layer structure. 5 has a solder layer 42 as a single conductive layer. The conductive particles 41 include base material particles 32 and a solder layer 42 disposed on the surface of the base material 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 substrate particles are preferably resin particles formed of a resin. When connecting between electrodes using electroconductive particle, after arrange | positioning electroconductive particle between electrodes, electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles, the conductive particles are easily deformed during the pressure bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes still higher.

  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 monomer having an ethylenically unsaturated group, the monomer having the ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer. And a polymer.

  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) acrylates such as meth) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Esters; 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 Is mentioned.

  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) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure And silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane It is done.

  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 and carbon black. 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 method for forming the conductive layer on the surface of the base particle and the method for forming the solder layer on the surface of the base particle or the surface of the second conductive layer are not particularly limited. As a method of forming the conductive layer and the solder layer, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, And a method of coating the surface of the substrate particles with a paste containing metal powder or metal powder and a binder. Among these, a method using electroless plating, electroplating, or physical collision is preferable. 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 base particle is preferably higher than the melting point of the solder layer. 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 solder layer. The conductive particles may have a plurality of conductive layers (solder layer, second conductive layer). That is, in the conductive particles, two or more conductive layers may be stacked.

  The solder is preferably a low melting point metal having a melting point of 450 ° C. or lower. The solder layer is preferably a 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 low melting point metal particles having a melting point of 450 ° C. or lower. The low melting point metal particles are particles containing a low melting point metal. The low melting point metal is a metal having a melting point of 450 ° C. or lower. The melting point of the low melting point metal is preferably 300 ° C. or lower, more preferably 160 ° C. or lower. The solder in the conductive particles preferably contains tin. In 100% by weight of the metal contained in the solder layer 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 in the solder in the conductive particles is equal to or higher than the 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 conductive surface, 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 conductive surface increases the bonding strength between the solder and the electrode. As a result, peeling between the solder and the electrode is further less likely to occur, and conduction reliability and conduction reliability are improved. Effectively high.

  The low melting point metal constituting the solder in the conductive 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. Especially, since it is excellent in the wettability with respect to an electrode, it is preferable that the said low melting metal is a tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, and a tin-indium alloy. More preferred are a tin-bismuth alloy and a tin-indium alloy.

  The material constituting the solder (solder layer) is preferably a filler material having a liquidus of 450 ° C. or less 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. Among them, a tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic) which is low-melting and lead-free is preferable. That is, the solder preferably does not contain lead, and is preferably a solder containing tin and indium or a solder containing tin and bismuth.

  In order to further increase the bonding strength between the solder and the electrode, the solder in the conductive particles 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 layer or conductive particles, the content of these metals for increasing the bonding strength is preferably 100% by weight 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 layer is preferably higher than the melting point of the solder layer. The melting point of the second conductive layer is preferably above 160 ° C, more preferably above 300 ° C, even more preferably above 400 ° C, even more preferably above 450 ° C, particularly preferably above 500 ° C, most preferably Preferably it exceeds 600 degreeC. Since the solder layer has a low melting point, it melts during conductive connection. The second conductive layer is preferably not melted at the time of conductive connection. The conductive particles are preferably used after melting solder, preferably used after melting the solder layer, and used without melting the second conductive layer while melting the solder layer. It is preferred that Since the melting point of the second conductive layer is higher than the melting point of the solder layer, only the solder layer can be melted without melting the second conductive layer at the time of conductive connection.

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

  The second conductive layer preferably contains a metal. The metal constituting the second conductive layer is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium 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 layer 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 layers for the connection between the electrodes, the connection resistance between the electrodes is further reduced. In addition, a solder layer can be more easily formed on the surface of these preferable conductive layers.

  The thickness of the solder layer 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 layer is not less than the above lower limit and not more than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed at the time of connection between the electrodes. .

(Binder resin)
The binder resin is not particularly limited. In general, an insulating resin is used as the binder resin. The conductive material and the binder resin preferably contain a thermosetting component (thermosetting compound) or a thermosetting component. The conductive material and the binder resin may contain a thermoplastic component (thermoplastic compound) or may contain a thermosetting component. The conductive material and the binder resin preferably contain a thermosetting component. The thermosetting component preferably contains a curable compound that can be cured by heating and a thermosetting agent.

  Examples of the thermoplastic compound include phenoxy resin, urethane resin, (meth) acrylic resin, polyester resin, polyimide resin, and polyamide resin.

  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. Among these, an epoxy compound is preferable from the viewpoint of further improving the curability and viscosity of the conductive material and further improving the conduction reliability.

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

  The thermosetting agent thermosets the thermosetting compound. Examples of the thermosetting agent include an imidazole curing agent, an amine curing agent, a phenol curing agent, a polythiol curing agent, an acid anhydride, a thermal cation initiator, 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.

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

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

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

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

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

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

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

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

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

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

(flux)
The conductive material preferably contains a flux. By using flux, the solder can be more effectively placed on the electrode. The flux is not particularly limited. As the flux, a flux generally used for soldering or the like can be used. Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an organic acid, and pine resin. Etc. As for the said flux, only 1 type may be used and 2 or more types may be used together.

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

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

  The 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 160 ° C. or lower, even more preferably 150 ° C. or lower, still more preferably. 140 ° C. or lower. When the melting point of the flux is not less than the above lower limit and not more than the above upper limit, the flux effect is more effectively exhibited, and the conductive particles are more efficiently arranged on the electrode. The melting point of the flux is preferably 80 ° C. or higher and 190 ° C. or lower. The melting point of the flux is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

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

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

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

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

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

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

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

(Filler)
The conductive material preferably contains a filler. By using the filler, latent heat expansion of the cured material of the conductive material can be suppressed. As for the said filler, only 1 type may be used and 2 or more types may be used together.

  Examples of the filler include inorganic fillers such as silica, talc, aluminum nitride, and alumina. The filler may be an organic filler or an organic-inorganic composite filler. As for the said filler, only 1 type may be used and 2 or more types may be used together.

  Each of the conductive material and the filler preferably contains an inorganic filler. By using the inorganic filler, the specific gravity and thixotropy of the conductive material can be controlled to a more suitable range, the sedimentation of the conductive particles can be further suppressed, and the conduction reliability of the connection structure can be further enhanced.

  Each of the conductive material and the filler preferably contains silica. The silica is a silica filler. By using silica, the specific gravity and thixotropy of the conductive material can be controlled in a more suitable range, the sedimentation of the conductive particles can be further suppressed, and the conduction reliability of the connection structure can be further enhanced.

  The content of the filler in 100% by weight of the conductive material is preferably 2% by weight or more, more preferably 5% by weight or more, preferably 60% by weight or less, more preferably 50% by weight or less. When the content of the filler is not less than the above lower limit and not more than the above upper limit, the conductive particles are more efficiently arranged on the electrode.

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

  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.

(Synthesis Example 1)
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) has a hydroxyl group derived from bisphenol F, 1,6-hexanediol diglycidyl ether, and an epoxy group of bisphenol F type epoxy. It was confirmed that the unit had a bonded structural unit in the main chain and 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.

(Example 1)
(1) Production of anisotropic conductive paste 100 parts by weight of the polymer A obtained above, 22 parts by weight of a thermosetting compound (resorcinol type epoxy compound, “EX-201” manufactured by Nagase ChemteX Corporation), and thermosetting 7 parts by weight of a compound (bisphenol F type epoxy resin, “EVA-830CRP” manufactured by DIC) and 20 parts by weight of a thermosetting agent (pentaerythritol tetrakis (3-mercaptobutyrate), “Karenz MT PE1” manufactured by Showa Denko KK) And 2 parts by weight of flux (glutaric acid, manufactured by Wako Pure Chemical Industries), 2 parts by weight of a latent epoxy thermosetting agent (“Fujicure 7000” manufactured by T & K TOKA), and a latent thermosetting agent (microcapsule type, Asahi Kasei E-Materials "HXA-3932HP") 0.5 parts by weight and conductive particles (solder particles, Sn-58Bi is It particles, melting point 139 ° C., Mitsui Mining & Smelting Co., Ltd. "DS10-25", average particle size 10 [mu] m) were blended and 35 parts by weight, to obtain an anisotropic conductive paste.

(2) Production of connection structure (L / S = 75 μm / 75 μm) Glass epoxy substrate (FR-4) having a copper electrode pattern (first electrode, copper electrode thickness 10 μm) having L / S of 75 μm / 75 μm on the upper surface Board | substrate) (1st connection object member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (2nd electrode, copper electrode thickness 10 micrometers) with L / S of 75 micrometers / 75 micrometers on the lower surface was prepared. Further, a non-opaque polyethylene terephthalate plate (thickness: 100 μm) was laminated and adhered as a reinforcing member on the upper surface of the flexible printed board.

  In addition, a solder resist film was disposed on the copper electrode in a region of the glass epoxy substrate that did not face the flexible printed board. A coverlay was placed on the copper electrode in a region of the flexible printed circuit board not facing the glass epoxy substrate.

  The connection structure was fabricated so that the overlapping area of the glass epoxy substrate and the flexible printed circuit board was 1.5 cm × 4 mm and the number of connected electrodes was 100 pairs. An anisotropic conductive paste layer was formed on the upper surface of the glass epoxy substrate by coating the anisotropic conductive paste to a thickness of 50 μm. Next, the flexible printed circuit board on which the reinforcing member was laminated and adhered was laminated on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other. The weight of the reinforcing member and the flexible printed board is added to the anisotropic conductive paste layer. Thereafter, while heating the anisotropic conductive paste layer to a temperature of 185 ° C., the solder was melted and the anisotropic conductive paste layer was cured at 185 ° C. to obtain a connection structure.

(Example 2)
A connection structure was obtained in the same manner as in Example 1 except that a non-opaque polyethylene terephthalate plate (thickness: 200 μm) was used as the reinforcing member.

(Example 3)
A connection structure was obtained in the same manner as in Example 1 except that a non-opaque polyethylene terephthalate plate (thickness 300 μm) was used as the reinforcing member.

Example 4
A connection structure was obtained in the same manner as in Example 1 except that a non-opaque polyethylene terephthalate plate (thickness 500 μm) was used as the reinforcing member.

(Example 5)
A connection structure was obtained in the same manner as in Example 1 except that a non-opaque polyethylene terephthalate plate (thickness: 1000 μm) was used as the reinforcing member.

(Comparative Example 1)
A connection structure was obtained in the same manner as in Example 1 except that the reinforcing member was not used.

(Evaluation)
(1) Maximum distance of positional deviation between electrodes By observing a cross section of the obtained connection structure, the maximum distance of positional deviation between the upper and lower electrodes was evaluated. The maximum distance of misalignment between electrodes was determined according to the following criteria.

[Criteria for determining the maximum distance between electrodes]
◯: The maximum distance between the electrodes is less than 5 μm. ○: The maximum distance between the electrodes is 5 μm or more and less than 20 μm. Δ: The maximum distance between the electrodes is 20 μm or more and less than 40 μm. The maximum distance of misalignment is 40 μm or more

(2) Conduction reliability between upper and lower electrodes In the obtained connection structure (n = 15), initial connection resistance A between the upper and lower electrodes was measured by a four-terminal method. The average value of the connection resistance A 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

(3) Bending resistance About the obtained connection structure (n = 15 pieces), the edge part of the flexible printed circuit board which is a 2nd connection object member is hold | gripped, and a 1st connection object member is 180 degree direction. Bending stress was applied to the connection structure by bending. After applying bending stress, the initial connection resistance B between the upper and lower electrodes was measured by the four-terminal method. The average value of the connection resistance B was calculated.

[Criteria for bending resistance]
○○: The average value of connection resistance B is less than 125% compared to the average value of connection resistance A ○: The average value of connection resistance B is 125% or more and less than 150% compared to the average value of connection resistance A △: Connection Compared to the average value of the resistance A, the average value of the connection resistance B is 150% or more and less than 200%. X: The average value of the connection resistance B is 200% or more compared to the average value of the connection resistance A.

  The results are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 1 ... Connection structure 2 ... 1st connection object member 2a ... 1st electrode 3 ... 2nd connection object member 3a ... 2nd electrode 4 ... Connection part 5 ... Reinforcement member 6 ... Solder resist film 7 ... Coverlay DESCRIPTION OF SYMBOLS 20 ... Conductive material layer 21 ... Conductive particle 31 ... Conductive particle 32 ... Base particle 33 ... Conductive layer 33A ... 2nd conductive layer 33B ... Solder layer 41 ... Conductive particle 42 ... Solder layer

Claims (12)

A first connection target member having at least one first electrode on its surface;
A second connection target member having at least one second electrode on its surface;
A connecting portion connecting the first connection target member and the second connection target member in a state where the first electrode and the second electrode face each other;
A reinforcing member,
The second connection target member is a resin film, a flexible printed circuit board, or a flexible flat cable,
The connecting portion is formed of a conductive material including a plurality of conductive particles having a solder on a conductive outer surface, and a binder resin,
The first electrode and the second electrode are electrically connected by the solder in the conductive particles;
The second connection target member has a region facing the first connection target member via the connection portion, and faces the first connection target member of the second connection target member. The connection structure body in which the said reinforcement member is arrange | positioned on the surface on the opposite side to the said 1st connection object member side of the said 2nd connection object member.   The connection structure according to claim 1, wherein a Young's modulus of the reinforcing member is higher than a Young's modulus of the second connection target member.   The connection structure according to claim 1 or 2, wherein a Young's modulus of the first connection target member is higher than a Young's modulus of the second connection target member.   The connection structure according to claim 1, wherein the reinforcing member has a thickness of 100 μm or more and 1000 μm or less.   The connection structure according to claim 1, wherein the second connection target member has a region that does not face the first connection target member.   The connection structure according to claim 5, wherein a coverlay is disposed on the second electrode in a region of the second connection target member that is not opposed to the first connection target member.   The connection structure according to claim 1, wherein the first connection target member has a region that does not face the second connection target member.   The solder resist film is arrange | positioned on the said 1st electrode of the said 1st connection object member in the area | region which is not facing the said 2nd connection object member of the said 1st connection object member. The connection structure of any one of -7.   9. The reinforcing member according to any one of claims 1 to 8, wherein the reinforcing member is not opaque so that the position of the second electrode can be confirmed when the second electrode is viewed from the reinforcing member side. Connection structure.   The connection structure according to claim 1, wherein the conductive particles are solder particles. It is a manufacturing method of a connection structure given in any 1 paragraph of Claims 1-10,
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 plurality of conductive particles having solder on a conductive outer surface, and a conductive material including a binder resin;
Prepare a reinforcing member,
The second connection target member is a resin film, a flexible printed circuit board, or a flexible flat cable,
Disposing a conductive material layer on the surface of the first connection target member using the conductive material;
Disposing the second connection target member on the surface of the conductive material layer opposite to the first connection target member so that the first electrode and the second electrode face each other;
The conductive material layer forms a connection portion connecting the first connection target member and the second connection target member, and the first electrode and the second electrode are the conductive particles. Obtaining a connection structure electrically connected by the solder in
The second connection target member has a region facing the first connection target member via the connection portion, and faces the first connection target member of the second connection target member. The manufacturing method of the connection structure which obtains the connection structure in which the said reinforcement member is arrange | positioned on the surface on the opposite side to the said 1st connection object member side of the said 2nd connection object member.   In a state where the reinforcing member is disposed on the surface of the second connection target member before being disposed on the surface of the conductive material, the second connection target member in which the reinforcing member is disposed on the surface, The manufacturing method of the connection structure of Claim 11 arrange | positioned on the surface of the said electrically-conductive material layer.

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