JPWO2016013474A1 - Method for manufacturing connection structure - Google Patents

Abstract

Provided is a connection structure manufacturing method capable of reducing the amount of change in impedance. The method for manufacturing a connection structure according to the present invention includes a step of arranging a conductive paste on a surface of a first connection target member, and a second connection target member on the surface of the conductive paste. The step of disposing the electrode and the second electrode to face each other, and heating the conductive paste to a temperature equal to or higher than the melting point of the solder particles and equal to or higher than the curing temperature of the thermosetting component, thereby the first electrode and the second electrode. A step of electrically connecting the electrodes to each other by a solder portion in the connection portion, wherein the thickness of the solder portion is larger than an average particle diameter of the plurality of solder particles, and the solder portion The thickness is 80 μm or less.

Description

  The present invention relates to a method for manufacturing a connection structure using a conductive paste containing solder particles.

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

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

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

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

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

  In Patent Document 2, 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. 8 of Patent Document 2. In Patent Document 2, the conductive particles melt in a resin component that is not completely cured at a temperature at which the anisotropic conductive resin is heated.

WO2008 / 023452A1 JP 2004-260131 A

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

  Moreover, even if it is the anisotropic conductive paste containing solder powder, solder powder may not be efficiently arrange | positioned on an electrode (line). For this reason, the solder area | region arrange | positioned between electrodes may not become large enough.

  In addition, there is a problem that the amount of change in impedance becomes large in the conventional formation state of the solder region disposed between the electrodes.

  The objective of this invention is providing the manufacturing method of the connection structure which can make the variation | change_quantity of an impedance small.

  According to a wide aspect of the present invention, a conductive paste containing a thermosetting component and a plurality of solder particles, a first connection target member having at least one first electrode on the surface, and at least one second A step of disposing the conductive paste on the surface of the first connection target member using a second connection target member having an electrode on the surface; and the first connection target member side of the conductive paste; On the opposite surface, the step of disposing the second connection object member so that the first electrode and the second electrode face each other, the melting point of the solder particles and the thermosetting component The conductive paste is heated to a temperature equal to or higher than the curing temperature of the first connection target member and the second connection target member to form a connection portion connecting the first connection target member and the second connection target member, and the first 1 electrode and the second electrode And a step of electrically connecting with a solder part in the connection part, and the thickness of the solder part located between the first electrode and the second electrode in the obtained connection structure The solder that is larger than the average particle diameter of the plurality of solder particles contained in the conductive paste and that is located between the first electrode and the second electrode in the obtained connection structure A method for manufacturing a connection structure is provided in which the thickness of the part is 80 μm or less.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, the thickness of the solder portion located between the first electrode and the second electrode in the connection structure obtained is set as described above. The average particle diameter of the plurality of solder particles contained in the conductive paste is set to be twice or more.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, the thickness of the solder portion located between the first electrode and the second electrode in the connection structure obtained is set as described above. 0.2 times or more the thickness of the conductive paste on the first electrode before the second connection target member is arranged on the surface of the first connection target member, 0.9 Double or less.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection portion, no pressure is applied, and the conductive paste includes The weight of the second connection target member is added.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, the average particle diameter of the said several solder particle is 0.5 micrometer or more.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, content of the said some solder particle in the said electrically conductive paste is 10 to 60 weight%. The content of the plurality of solder particles in the conductive paste is particularly preferably 30% by weight or more.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, a said 2nd connection object member is a resin film, a flexible printed circuit board, a rigid flexible substrate, or a flexible flat cable.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, the electrode width of the said 1st electrode is 50 micrometers or more and 1000 micrometers or less, and the electrode width of the said 2nd electrode is 50 micrometers or more and 1000 micrometers or less. The interelectrode width of the first electrode is 50 μm or more and 1000 μm or less, the interelectrode width of the second electrode is 50 μm or more and 1000 μm or less, and in another specific aspect, The electrode width of one electrode is 50 μm or more and 300 μm or less, the electrode width of the second electrode is 50 μm or more and 300 μm or less, and the interelectrode width of the first electrode is 50 μm or more and 300 μm or less. And the inter-electrode width of the second electrode is not less than 50 μm and not more than 300 μm.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, the electrode width of the first electrode is located between the first electrode and the second electrode in the connection structure obtained. The thickness of the solder part is smaller than the thickness of the solder part, and the electrode width of the second electrode is located between the first electrode and the second electrode in the obtained connection structure. Smaller than the thickness, the interelectrode width of the first electrode is smaller than the thickness of the solder portion located between the first electrode and the second electrode in the resulting connection structure, The interelectrode width of the second electrode is smaller than the thickness of the solder portion located between the first electrode and the second electrode in the obtained connection structure.

  The manufacturing method of the connection structure according to the present invention includes a conductive paste containing a thermosetting component and a plurality of solder particles, a first connection target member having at least one first electrode on the surface, and at least one A step of disposing the conductive paste on the surface of the first connection target member using a second connection target member having a second electrode on the surface; and the first connection target of the conductive paste. A step of disposing the second connection object member on a surface opposite to the member side so that the first electrode and the second electrode face each other; a temperature equal to or higher than a melting point of the solder particles and the heat The conductive paste is heated to a temperature equal to or higher than the curing temperature of the curable component, thereby forming a connection portion connecting the first connection target member and the second connection target member with the conductive paste, and The first electrode and the first electrode A step of electrically connecting the first electrode and the second electrode to each other by a solder portion in the connection portion, and being positioned between the first electrode and the second electrode in the connection structure obtained. Since the thickness of the solder part is larger than the average particle diameter of the plurality of solder particles contained in the conductive paste, the amount of change in impedance in the obtained connection structure can be reduced. Furthermore, in the present invention, in the obtained connection structure, the thickness of the solder portion located between the first electrode and the second electrode is set so that the plurality of solder particles contained in the conductive paste are included. Since the thickness of the solder portion positioned between the first electrode and the second electrode in the obtained connection structure is not more than the average particle diameter, the thickness is 80 μm or less. It is possible to effectively reduce the amount of change in impedance in the connected structure.

FIG. 1 is a partially cutaway front sectional view schematically showing a connection structure according to an embodiment of the present invention. FIGS. 2A to 2C are diagrams for explaining each step of an example of the method for manufacturing the connection structure according to the embodiment of the present invention. FIG. 3 is a partially cutaway front sectional view showing a modified example of the connection structure.

  Details of the present invention will be described below.

  In the method for manufacturing a connection structure according to the present invention, a conductive paste including a thermosetting component and a plurality of solder particles, a first connection target member having at least one first electrode on the surface, and at least one The 2nd connection object member which has a 2nd electrode on the surface is used.

  In the manufacturing method of the connection structure according to the present invention, the step of disposing the conductive paste on the surface of the first connection target member, and the surface of the conductive paste opposite to the first connection target member side Above, the step of arranging the second connection target member so that the first electrode and the second electrode face each other, the melting point of the solder particles or more and the curing temperature of the thermosetting component or more The conductive paste is heated to form a connection portion connecting the first connection target member and the second connection target member with the conductive paste, and the first electrode and Electrically connecting the second electrode to a solder portion in the connection portion.

  In the method for manufacturing a connection structure according to the present invention, the thickness of the solder portion located between the first electrode and the second electrode in the connection structure obtained is included in the conductive paste. The thickness of the solder portion that is larger than the average particle diameter of the plurality of solder particles and is located between the first electrode and the second electrode in the obtained connection structure is 80 μm or less. To.

  In the method for manufacturing a connection structure according to the present invention, since the above-described configuration is employed, the amount of change in impedance in the obtained connection structure can be reduced. Furthermore, in the manufacturing method of the connection structure according to the present invention, since the above-described configuration is adopted, a plurality of solder particles gathers between the electrodes, and the plurality of solder particles are efficiently arranged on the electrodes (lines). can do. Moreover, it is difficult for some of the plurality of solder particles to be disposed in a region (space) where no electrode is formed, and the amount of solder particles disposed in a region where no electrode is formed can be considerably reduced. Therefore, the conduction reliability between the electrodes can be improved. In addition, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, and to improve insulation reliability.

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

  Next, as a method of selectively aggregating the solder particles on the surface of the electrode, the electrode material having good wettability of the molten solder particles and another surface material having poor wettability of the molten solder particles were formed. A method of selecting a member to be connected, selectively adhering molten solder particles that have reached the surface of the electrode to the electrode, melting another solder particle on the molten solder particle, and thermal conductivity. Select a connection target member made of a good electrode material and other surface material with poor thermal conductivity, and when heat is applied, the temperature of the electrode is made higher than that of other surface members. In the method of melting solder on the electrode, the solder particles are selectively applied to the electrode by using solder particles processed to have a positive charge with respect to the negative charge existing on the electrode formed of metal. And a method of selectively aggregating solder particles on the electrode by making the resin other than the solder particles in the conductive paste hydrophobic with respect to the electrode having a hydrophilic metal surface. It is done.

  Moreover, as a method of making the thickness of the solder part larger than the average particle diameter of the plurality of solder particles, a method of delaying the increase in viscosity at the time of curing of the conductive paste, a method of reducing the viscosity of the conductive paste, A method of increasing the content of solder particles, a method of increasing the zeta potential of the surface of the solder particles, a method of reducing the melt viscosity of the conductive paste at the melting point temperature of the solder, and a step of arranging the second connection target member In the step of forming the connection part, a method in which no pressurization is performed may be used. By appropriately controlling these, the thickness of the solder portion can be made larger than the average particle diameter of the plurality of solder particles.

  The thickness of the solder part is preferably 1.2 times or more, more preferably 2 times or more, and further preferably 3 times or more the average particle diameter of the plurality of solder particles. When the thickness of the solder portion is appropriately larger than the average particle diameter of the plurality of solder particles, the amount of change in impedance is further effectively reduced. The thickness of the solder part is preferably 10 times or less the average particle diameter of the plurality of solder particles.

  In order to reduce the amount of change in impedance, there are a method of increasing the thickness of the solder portion, a method of increasing the solder wet area on the electrode, a method of reducing the resin component of the conductive paste existing on the electrode, and the like. By increasing the thickness of the solder part, it is possible to reduce the influence of the capacitance due to the presence of the resin component of the conductive paste between the upper and lower electrodes, and to reduce the amount of impedance change at the connection part. By increasing the solder wetting area on the electrode, the connection resistance at the connection portion can be reduced, and the amount of impedance change at the connection portion can be reduced.

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

  The amount of change in impedance is measured using a digitizing oscilloscope in the obtained connection structure by the TDR (time domain reflectometry) method, the characteristic impedance of the connection part, and the characteristic of the connection target member. It can be obtained from the difference from the impedance. For example, “DSA8200” manufactured by Tektronix is used as a test apparatus, and “P80318” manufactured by Tektronix is used as a measurement probe. Further, at the time of measurement, it is preferable to measure the characteristic impedance of the differential wiring.

  In the obtained connection structure, the thickness of the solder portion located between the first electrode and the second electrode is arranged on the surface of the first connection target member, and the second Preferably, the thickness of the conductive paste on the first electrode before the connection target member is arranged is 0.2 times or more, more preferably 0.3 times or more, preferably 0.9 times or less, more Preferably it is 0.8 times or less. When the thickness of the solder portion is not less than the lower limit and not more than the upper limit of the thickness of the conductive paste, the amount of change in impedance is further effectively reduced.

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

  Thus, in order to efficiently arrange a plurality of solder particles on the electrode and to considerably reduce the amount of solder particles arranged in the region where the electrode is not formed, a conductive paste is used instead of a conductive film. The inventor has found that it needs to be used.

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

  In addition, WO2008 / 023452A1 describes that it is preferable to pressurize with a predetermined pressure at the time of bonding from the viewpoint of efficiently moving the solder powder to the electrode surface, and the pressurizing pressure further ensures the solder area. For example, it is described that the pressure is set to 0 MPa or more, preferably 1 MPa or more. Further, even if the pressure intentionally applied to the adhesive tape is 0 MPa, the member disposed on the adhesive tape It is described that a predetermined pressure may be applied to the adhesive tape by its own weight. In WO2008 / 023452A1, it is described that the pressure applied intentionally to the adhesive tape may be 0 MPa, but there is no difference between the effect when the pressure exceeding 0 MPa is applied and when the pressure is set to 0 MPa. Not listed. In WO2008 / 023452A1, no attention is paid to the relationship between the thickness of the solder portion (solder region) located between the electrodes and the average particle diameter of a plurality of solder powders contained in the adhesive tape. 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. In addition, the conductive film has a problem that the melt viscosity of the conductive film cannot be sufficiently lowered at the melting temperature of the solder, and the aggregation of the solder particles is hindered.

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

  First, FIG. 1 schematically shows a connection structure obtained by the method for manufacturing a connection structure according to an embodiment of the present invention in a partially cutaway front sectional view.

  The connection structure 1 shown in FIG. 1 is a connection that connects a first connection target member 2, a second connection target member 3, and the first connection target member 2 and the second connection target member 3. Part 4. The connection part 4 is formed of a conductive paste containing a thermosetting component and a plurality of solder 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. 1, in the connection structure 1, a plurality of solder particles gather between the first electrode 2 a and the second electrode 3 a, and after the plurality of solder particles melt, After the electrode surface wets and spreads, it solidifies to form the solder portion 4A. The thickness of the solder portion 4A located between the first electrode 2a and the second electrode 3a in the connection structure 1 is larger than the average particle diameter of the plurality of solder particles contained in the conductive paste. Moreover, the thickness of the solder part 4A located between the first electrode 2a and the second electrode 3a in the connection structure 1 is 80 μm or less. For this reason, the connection area of the solder part 4A and the first electrode 2a, and the solder part 4A and the second electrode 3a is effectively increased. That is, by using the solder particles, the solder portion 4A, the first electrode 2a, and the solder portion are compared with the case where the conductive outer surface is made of a metal such as nickel, gold or copper. The contact area between 4A and the second electrode 3a increases. Also by this, the amount of change in impedance in the connection structure 1 can be reduced. Further, the conduction reliability and connection reliability in the connection structure 1 are increased. Note that the conductive paste may contain a flux. When the conductive paste contains a flux, the flux is generally gradually deactivated by heating.

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

  If the amount of solder particles used is reduced, the connection structure 1 can be easily obtained. If the amount of the solder particles used is increased, it becomes easy to obtain the connection structure 1X. When the amount of solder particles used is large, the thickness of the solder portion located between the first electrode and the second electrode in the connection structure is set to the average particle of the plurality of solder particles contained in the conductive paste. It is easy to make it larger than the diameter.

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

  First, the 1st connection object member 2 which has the 1st electrode 2a on the surface (upper surface) is prepared. Next, as shown in FIG. 2A, a conductive paste 11 including a thermosetting component 11B and a plurality of solder particles 11A is disposed on the surface of the first connection target member 2 (first Process). The conductive paste 11 is disposed on the surface of the first connection target member 2 on which the first electrode 2a is provided. After the conductive paste 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 paste 11 is not particularly limited, and examples thereof include application with a dispenser, screen printing, and ejection with an inkjet device.

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

  In the present embodiment, no pressure is applied in the second step and the third step. In the present embodiment, the weight of the second connection target member 3 is added to the conductive paste 11. In this embodiment, a conductive paste is used instead of a conductive film. 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. As a result, the thickness of the solder part 4A between the first electrode 2a and the second electrode 3a tends to increase. In addition, if pressure is applied in at least one of the second step and the third step, the action of the solder particles trying to collect between the first electrode and the second electrode is hindered. The tendency to become higher. This has been found by the inventor.

  Moreover, in this embodiment, since pressurization is not performed, when the second connection target member is superimposed on the first connection target member to which the conductive paste 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 between the electrode of the first connection target member and the electrode of the second connection target member. As the area where the solder and other components of the conductive paste are in contact with each other is minimized, the energy becomes more stable, and the force that makes the connection structure with alignment, which is the connection structure with the smallest area, works. is there. At this time, it is desirable that the conductive paste is not cured and that the viscosity of components other than the solder particles of the conductive paste is sufficiently low at that temperature and time.

  The viscosity of the conductive paste at the melting point temperature of the solder is preferably 50 Pa · s or less, more preferably 10 Pa · s or less, still more preferably 1 Pa · s or less, preferably 0.1 Pa · s or more, more preferably 0.2 Pa. -It is more than s. If the viscosity is below a predetermined viscosity, the solder particles can be efficiently aggregated.If the viscosity is above the predetermined viscosity, the void at the connection portion is suppressed, and the conductive paste is prevented from protruding beyond the connection portion. In addition, it becomes easy to make the solder thickness between the upper and lower electrodes equal to or larger than the average particle diameter of the solder particles.

  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 paste 11, and the 2nd connection object member 3 is moved to a heating member, The said 3rd You may perform a process. In order to perform the heating, the laminate may be disposed on a heating member, or the laminate may be disposed in a heated space.

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

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

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

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

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

Moreover, when using the heat gun which provides a hot air, you may pressurize from a connection structure upper part by the wind pressure of a hot air in the range which does not inhibit the self-aggregation of a solder too much. A preferable wind pressure is preferably 1 g or more, more preferably 10 g or more, preferably 500 g or less, more preferably 100 g or less per 1 cm ² . If a wind pressure is more than the said minimum and below the said upper limit, the curvature of a 1st connection object member can be suppressed, the deformation | transformation by a heat | fever can be suppressed, and the solder part of uniform thickness can be formed between electrodes. When the wind pressure is less than or equal to the above upper limit, the thickness of the solder portion between the electrodes is hardly excessively reduced, and the amount of change in impedance is effectively reduced.

  From the viewpoint of further improving the conduction reliability, when the portion where the first electrode and the second electrode are opposed to each other in the stacking direction of the first electrode, the connection portion, and the second electrode is viewed, It is preferable to obtain a connection structure in which the solder portion in the connection portion is disposed in 50% or more of the area of 100% of the portion where the electrode and the second electrode face each other.

  In addition, the said 1st connection object member should just have at least 1 1st electrode. The first connection target member preferably has a plurality of first electrodes. The said 2nd connection object member should just have at least 1 2nd electrode. The second connection target member preferably has a plurality of second electrodes.

  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 particle not to gather on an electrode. On the other hand, even if a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board is used, the conductive reliability between the electrodes can be sufficiently enhanced by efficiently collecting the solder particles on the electrodes. it can. 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.

  When 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 first connection target member and the first connection target member In at least one of the two connection target members, a reinforcing plate may be disposed on the surface opposite to the electrode side. The reinforcing plate is preferably disposed on the surface of the resin film, flexible printed board, flexible flat cable, or rigid flexible board opposite to the electrode side. The thickness of the reinforcing plate is preferably 50 μm or more, more preferably 75 μm or more, preferably 300 μm or less, more preferably 150 μm or less. The curvature of a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board can be fully suppressed as the said thickness is more than the said minimum. When the thickness is less than or equal to the above upper limit, the temperature of the conductive paste is sufficiently high during heating, and the melting of the solder, the aggregation of the solder, and the curing of the resin proceed even better.

  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, 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.

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

  The minimum value of viscosity of the conductive paste (minimum melt viscosity value) in a temperature range of 25 ° C. or higher and the melting point of the solder particles (solder) is preferably 0.1 Pa · s or higher, more preferably 0. .2 Pa · s or more, preferably 10 Pa · s or less, more preferably 1 Pa · s or less. When the minimum value of the viscosity is not less than the above lower limit and not more than the above upper limit, the solder particles can be arranged more efficiently on the electrode.

  The minimum value of the above viscosity is STRESSTECH (manufactured by EOLOGICA), etc., strain control 1 rad, frequency 1 Hz, heating rate 20 ° C./min, measurement temperature range 40 to 200 ° C. (however, the melting point of solder particles is 200 ° C. In the case of exceeding the upper limit of the temperature, the melting point of the solder particles is taken into account). From the measurement result, the minimum value of the viscosity in the temperature region of the solder particle melting point or lower is evaluated.

  From the viewpoint of effectively reducing the amount of change in impedance, the electrode width of the first electrode and the electrode width of the second electrode are preferably 50 μm or more, more preferably 75 μm or more, preferably 1000 μm or less, more Preferably it is 500 micrometers or less, More preferably, it is 300 micrometers or less, Most preferably, it is 200 micrometers or less. The electrode width is the width of the line (L) in L / S. From the viewpoint of effectively reducing the amount of change in impedance, the interelectrode width of the first electrode and the interelectrode width of the second electrode are preferably 50 μm or more, more preferably 75 μm or more, and preferably 1000 μm or less. More preferably, it is 500 μm or less, more preferably 300 μm or less, and particularly preferably 200 μm or less. The inter-electrode width is the width of the space (S) in L / S.

  From the viewpoint of effectively reducing the amount of change in impedance, the electrode width of the first electrode and the electrode width of the second electrode are located between the upper first electrode and the second electrode. It is preferable that the thickness is smaller than the thickness of the solder part. From the viewpoint of effectively reducing the amount of change in impedance, the absolute value of the difference between the electrode width of the first electrode and the thickness of the solder portion, the electrode width of the second electrode and the thickness of the solder portion, The absolute value of the difference is preferably 1 μm or more, more preferably 5 μm or more, preferably 25 μm or less, more preferably 20 μm or less. From the viewpoint of effectively reducing the amount of change in impedance, the interelectrode width of the first electrode and the interelectrode width of the second electrode are set between the upper first electrode and the second electrode. It is preferable that it is smaller than the thickness of the said solder part located. From the viewpoint of effectively reducing the amount of change in impedance, the absolute value of the difference between the interelectrode width of the first electrode and the thickness of the solder portion, and the interelectrode width of the second electrode and the solder portion The absolute value of the difference from the thickness is preferably 1 μm or more, more preferably 5 μm or more, preferably 25 μm or less, more preferably 20 μm or less.

  The conductive paste includes a thermosetting component and a plurality of solder particles. The thermosetting component preferably includes a curable compound (thermosetting compound) that can be cured by heating, and a thermosetting agent. From the viewpoint of effectively removing the oxide film on the surface of the solder particles and the surface of the electrode, further reducing the amount of change in impedance, and further reducing the connection resistance, the conductive paste preferably contains a flux.

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

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

  From the viewpoint of efficiently collecting solder particles on the electrode and effectively reducing the amount of change in impedance in the connection structure, the zeta potential on the surface of the solder particles is preferably positive. However, in the present invention, even if the zeta potential on the surface of the solder particles is not positive, the effect of the present invention is exhibited by the configuration of the present invention.

  The zeta potential is measured as follows.

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

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

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

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

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

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

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

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

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

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

  The solder is preferably a low melting point metal having a melting point of 450 ° C. or lower. The solder particles are 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 particles include tin. In 100% by weight of the metal contained in the solder particles, the content of tin is preferably 30% by weight or more, more preferably 40% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the content of tin in the solder particles is equal to or higher than the lower limit, the connection reliability between the solder portion and the electrode is further enhanced.

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

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

  The low melting point metal constituting the solder particles is not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. Examples of the alloy include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, a tin-zinc alloy, and a tin-indium alloy. 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 solder particles are preferably a filler material having a liquidus line of 450 ° C. or lower based on JIS Z3001: welding terms. Examples of the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. 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 particles preferably do not contain lead, and preferably contain tin and indium, or contain tin and bismuth.

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

  The average particle diameter of the solder particles is less than 80 μm. The average particle diameter of the solder particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more, particularly preferably 5 μm or more, preferably 75 μm or less, more preferably 40 μm or less, and even more preferably 30 μm. Hereinafter, it is more preferably 20 μm or less, particularly preferably 15 μm or less, and most preferably 10 μm or less. When the average particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently arranged on the electrode. The average particle diameter of the solder particles is particularly preferably 3 μm or more and 30 μm or less.

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

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

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

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

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

  In particular, the content of the solder particles in 100% by weight of the conductive paste is preferably 1% by weight or more, and preferably 80% by weight or less. In this case, solder particles efficiently gather on the electrode, and the amount of change in impedance in the connection structure is effectively reduced.

(Compound curable by heating: thermosetting component)
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 paste and further improving the connection reliability.

  An aromatic epoxy compound is mentioned as said epoxy compound. Among these, crystalline epoxy compounds such as resorcinol type epoxy compounds, naphthalene type epoxy compounds, biphenyl type epoxy compounds, and benzophenone type epoxy compounds are preferable. An epoxy compound that is solid at normal temperature (23 ° C.) and has a melting temperature equal to or lower than the melting point of the solder is preferable. The melting temperature is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and preferably 40 ° C. or higher. By using the preferable epoxy compound, the first connection target member, the second connection target member, and the like when the connection target member is pasted together have a high viscosity and an impact such as conveyance is applied. In addition, the viscosity of the conductive paste can be greatly reduced by heat at the time of curing, and the aggregation of solder particles can be efficiently advanced.

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

(Thermosetting agent: thermosetting component)
The thermosetting agent thermosets the thermosetting compound. Examples of the thermosetting agent include 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 paste 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 solder particles are more efficiently arranged on the electrode. The reaction initiation temperature of the thermosetting agent is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

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

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

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, preferably 200 parts by weight or less, more preferably 100 parts by weight with respect to 100 parts by weight of the thermosetting compound. Part or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is at least the above lower limit, it is easy to sufficiently cure the conductive paste. 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 paste 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 active temperature (melting point) of the flux is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, further preferably 80 ° C. or higher, preferably 200 ° C. or lower, more preferably 190 ° C. or lower, even more preferably 160 ° C. or lower. More preferably, it is 150 ° C. or less, and still more preferably 140 ° C. or less. When the activation temperature of the flux is not less than the above lower limit and not more than the above upper limit, the flux effect is more effectively exhibited, and the solder particles are more efficiently arranged on the electrode. The activation temperature of the flux is preferably 80 ° C. or higher and 190 ° C. or lower. The active temperature of the flux is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

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

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

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

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

  The said flux may be disperse | distributed in the electrically conductive paste and may adhere on the surface of the solder particle.

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

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

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

  In 100% by weight of the conductive paste, the content of the flux is preferably 0.5% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. The conductive paste may not contain a 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.

(Other ingredients)
If necessary, the conductive paste is, 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. 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.

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 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 a catalyst for addition reaction of a hydroxyl group and an epoxy group, was added, and an addition polymerization reaction was carried out at 150 ° C. for 6 hours under a nitrogen flow to obtain a reactant (polymer). 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.

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

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

  Thermosetting compound 2: bisphenol F type epoxy resin, “EPICLON EXA-830CRP” manufactured by DIC

  Thermosetting agent 1: pentaerythritol tetrakis (3-mercaptobutyrate), “Karenz MT PE1” manufactured by Showa Denko KK

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

  Flux 1: Adipic acid, manufactured by Wako Pure Chemical Industries, Ltd., melting point (activation temperature) 152 ° C.

  Flux 2: Glutaric acid, manufactured by Wako Pure Chemical Industries

Method for producing solder particles 1-3:
Solder particles having anionic polymer 1: 200 g of solder particle body, 40 g of adipic acid, and 70 g of acetone are weighed in a three-necked flask, and then dehydration condensation between the hydroxyl group on the surface of the solder particle body and the carboxyl group of adipic acid 0.3 g of dibutyltin oxide as a catalyst was added and reacted at 60 ° C. for 4 hours. Thereafter, the solder particles were collected by filtration.

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

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

(Zeta potential measurement)
Moreover, 0.05 g of solder particles having the anion polymer 1 were put in 10 g of methanol and the resulting solder particles were uniformly dispersed by ultrasonic treatment to obtain a dispersion. The zeta potential was measured by electrophoretic measurement using this dispersion and “Delsamax PRO” manufactured by Beckman Coulter.

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

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

  Solder particles 1 (SnBi solder particles, melting point 139 ° C., solder particles main body selected from Mitsui Kinzoku “ST-3”), surface-treated solder particles having anionic polymer 1, average particle diameter 4 μm, CV value 7%, zeta potential on the surface: +0.65 mV, polymer molecular weight Mw = 6500)

  Solder particle 2 (SnBi solder particle, melting point 139 ° C., solder particle body selected from Mitsui Kinzoku “DS10”, surface-treated solder particle having anionic polymer 1, average particle diameter 13 μm, CV value 20% Surface zeta potential: +0.48 mV, polymer molecular weight Mw = 7000)

  Solder particle 3 (SnBi solder particle, melting point 139 ° C., solder particle body selected from “10-25” manufactured by Mitsui Kinzoku Co., Ltd., surface-treated anionic polymer 1 solder particle, average particle diameter 25 μm, CV value 15%, surface zeta potential: +0.4 mV, polymer molecular weight Mw = 8000)

  Solder particles 4 (SnBi solder particles, melting point 139 ° C., solder particles having an anionic polymer 1 subjected to surface treatment using a solder particle body, average particle diameter 55 μm, CV value 7%, surface zeta potential: +0.65 mV, Polymer molecular weight Mw = 6500)

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

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

  Phenoxy resin (“YP-50S” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)

(Examples 1-8)
(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 (L / S = 50 μm / 50 μm) Glass epoxy substrate having a copper electrode pattern (copper electrode thickness 12 μm) having an L / S of 50 μm / 50 μm and an electrode length of 3 mm on the upper surface (FR-4 substrate) (first connection target member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (thickness of a copper electrode 12 micrometers) of L / S 50 micrometers / 50 micrometers and electrode length 3mm on the lower surface was prepared.

  The overlapping area of the glass epoxy substrate and the flexible printed circuit board was 1.5 cm × 3 mm, and the number of connected electrodes was 75 pairs.

  Both the glass epoxy board and the flexible printed board were prepared by adjusting the thickness between the electrode and the ground layer so that the characteristic impedance of the differential wiring was 90Ω.

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

(3) Production of second connection structure (L / S = 75 μm / 75 μm) Glass epoxy substrate having a L / S of 75 μm / 75 μm and an electrode length of 3 mm on a copper electrode pattern (copper electrode thickness 12 μm) on the upper surface (FR-4 substrate) (first connection target member) was prepared. In addition, a flexible printed circuit board (second connection target member) having a L / S of 75 μm / 75 μm and an electrode length of 3 mm on the lower surface of a copper electrode pattern (copper electrode thickness 12 μm) was prepared.

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

(4) Production of third connection structure (L / S = 100 μm / 100 μm) Glass epoxy substrate having a copper electrode pattern (copper electrode thickness 12 μm) with L / S of 100 μm / 100 μm and electrode length of 3 mm on the upper surface (FR-4 substrate) (first connection target member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (thickness of copper electrode 12 micrometers) of L / S of 100 micrometers / 100 micrometers and electrode length 3mm on the lower surface was prepared.

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

(Comparative Example 1)
(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. First, second, and third connection structures were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used and a pressure of 1 MPa was applied during heating.

(Comparative Example 2)
A phenoxy resin (“YP-50S” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was dissolved in methyl ethyl ketone (MEK) so that the solid content was 50% by weight to obtain a solution. Ingredients other than the phenoxy resin shown in Table 1 below were blended with the blending amounts shown in Table 1 below and the total amount of the above solution, and after stirring for 5 minutes at 2000 rpm using a planetary stirrer, a bar coater was used. It was used and coated on a release PET (polyethylene terephthalate) film so that the thickness after drying was 30 μm. An anisotropic conductive film was obtained by removing MEK by vacuum drying at room temperature.

  First, second, and third connection structures were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive film was used and a pressure of 1 MPa was applied during heating.

(Comparative Example 3)
Except having used the anisotropic conductive film obtained by the comparative example 2, it carried out similarly to Example 1, and obtained the 1st, 2nd, 3rd connection structure.

(Comparative Examples 4-6)
The components shown in Table 1 below were blended in the blending amounts shown in Table 1 below to obtain anisotropic conductive paste. First, second, and third connection structures were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used.

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

  Moreover, the minimum melt viscosity of the anisotropic conductive paste in a temperature range from 25 ° C. to the melting point of the solder particles or the melting point of the solder on the surface of the conductive particles was measured using STRESSTECH (manufactured by EOLOGICA). The minimum melt viscosity was determined according to the following criteria.

[Minimum melt viscosity criteria]
A: 0.2 Pa · s or more and 10 Pa · s or less B: Does not correspond to the standard of A

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

(3) Evaluation of Impedance In the obtained connection structure, the characteristic impedance of the differential wiring was measured using “DSA8200” manufactured by Tektronix as the test device and “P80318” manufactured by Tektronix as the measurement probe. The measurement was performed using TDR (time domain reflectometry) and measurement conditions of 200 mV, 25 kHz, and a square wave (rise of 35 ps).

  With respect to the differential characteristic impedance of 90Ω of the used connection target member, the larger one of the differences between the maximum value and the minimum value of the impedance of the connection portion was defined as the impedance change amount of the connection portion. The impedance was determined according to the following criteria.

[Impedance criteria]
○: Impedance change is 5Ω or less ○: Impedance change is greater than 5Ω and 8Ω or less △: Impedance change is greater than 8Ω and less than 10Ω ×: Impedance change is greater than 10Ω

(4) Solder placement accuracy on the electrode In the cross section (cross section in the direction shown in FIG. 1) of the obtained connection structure, the cured product is separated from the solder portion disposed between the electrodes in 100% of the total area of the solder. The area (%) of the solder remaining inside was evaluated. In addition, the average of the area in five cross sections was computed. The placement accuracy of the solder on the electrode was determined according to the following criteria.

[Judgment criteria for placement accuracy of conductive particles on electrode]
OO: The area of the solder (solder particles) remaining in the cured product away from the solder portion arranged between the electrodes in the total area of 100% of the solder appearing in the cross section is 0% or more and 1% or less ○: Out of 100% of the total area of the solder appearing in the cross section, the area of the solder (solder particles) remaining in the cured product away from the solder portion disposed between the electrodes exceeds 1% and is 10% or less Δ: The area of the solder (solder particles) remaining in the cured product away from the solder portion arranged between the electrodes exceeds 100% in the total area of 100% of the solder appearing in the cross section, and is 30% or less X: Out of the total area of 100% of the solder appearing in the cross section, the area of the solder (solder particles) remaining in the cured product away from the solder portion disposed between the electrodes exceeds 30%

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

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

(6) Insulation reliability between adjacent electrodes In the obtained first, second and third connection structures (n = 15 pieces), they were left in an atmosphere of 85 ° C. and 85% humidity for 100 hours and then adjacent to each other. 5V was applied between the electrodes to be measured, and the resistance value was measured at 25 locations. Insulation reliability was judged according to the following criteria.

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

  The results are shown in Table 1 below.

  The same tendency was observed when a resin film, a flexible flat cable, and a rigid flexible board were used instead of the flexible printed board. In addition, in any of the connection structures obtained in the examples, 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, In addition, the solder portion in the connection portion is arranged in 50% or more of the area of 100% of the portion where the first electrode and the second electrode face each other. In any of the connection structures obtained in the examples, the solder wetted area on the electrode surface (the area where the solder in the exposed area of 100% of the electrode is in contact) was 50% or more.

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 paste 11A ... Solder particles 11B ... Thermosetting component

(Examples 1-7 and Reference Example 8)
(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.

The same tendency was observed when a resin film, a flexible flat cable, and a rigid flexible board were used instead of the flexible printed board. In each of the connection structures obtained in the examples and the reference examples , 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. As seen, the solder part in the connection part was arranged in 50% or more of the area of 100% of the part where the first electrode and the second electrode face each other. In each of the connection structures obtained in the examples and reference examples , the solder wetted area on the electrode surface (the area where the solder is in contact with 100% of the exposed area of the electrode) was 50% or more. It was.

Claims (11)

A conductive paste containing a thermosetting component and a plurality of solder particles, a first connection target member having at least one first electrode on the surface, and a second connection having at least one second electrode on the surface Using the target member,
Disposing the conductive paste on the surface of the first connection target member;
Disposing the second connection target member on the surface of the conductive paste opposite to the first connection target member side so that the first electrode and the second electrode face each other; ,
By connecting the first connection target member and the second connection target member by heating the conductive paste above the melting point of the solder particles and above the curing temperature of the thermosetting component, And forming the conductive paste and electrically connecting the first electrode and the second electrode by a solder portion in the connection portion,
In the obtained connection structure, the thickness of the solder portion located between the first electrode and the second electrode is larger than the average particle diameter of the plurality of solder particles contained in the conductive paste. And the manufacturing method of a connection structure which makes the thickness of the said solder part located between the said 1st electrode and the said 2nd electrode in the connection structure obtained as 80 micrometers or less.   In the obtained connection structure, the thickness of the solder portion located between the first electrode and the second electrode is twice the average particle diameter of the plurality of solder particles contained in the conductive paste. The manufacturing method of the connection structure according to claim 1 as described above.   In the obtained connection structure, the thickness of the solder portion located between the first electrode and the second electrode is arranged on the surface of the first connection target member, and the second The connection structure according to claim 1 or 2, wherein the thickness of the conductive paste on the first electrode before the connection target member is set to 0.2 times or more and 0.9 times or less. Production method.   The weight of the said 2nd connection object member is added to the said electrically conductive paste in the process of arrange | positioning a said 2nd connection object member, and the process of forming the said connection part, without applying pressure. The manufacturing method of the connection structure of any one of these.   The manufacturing method of the connection structure of any one of Claims 1-4 whose average particle diameter of the said some solder particle is 0.5 micrometer or more.   The manufacturing method of the connection structure of any one of Claims 1-5 whose content of the said some solder particle in the said electrically conductive paste is 10 to 60 weight%.   The manufacturing method of the connection structure of Claim 6 whose content of the said some solder particle in the said electrically conductive paste is 30 weight% or more.   The manufacturing method of the connection structure of any one of Claims 1-7 whose said 2nd connection object member is a resin film, a flexible printed circuit board, a rigid flexible substrate, or a flexible flat cable. The electrode width of the first electrode is 50 μm or more and 1000 μm or less,
The electrode width of the second electrode is 50 μm or more and 1000 μm or less,
The interelectrode width of the first electrode is 50 μm or more and 1000 μm or less,
The manufacturing method of the connection structure of any one of Claims 1-8 whose width between electrodes of a said 2nd electrode is 50 micrometers or more and 1000 micrometers or less. The electrode width of the first electrode is 50 μm or more and 300 μm or less,
The electrode width of the second electrode is 50 μm or more and 300 μm or less,
The interelectrode width of the first electrode is 50 μm or more and 300 μm or less,
The manufacturing method of the connection structure of Claim 9 whose width between electrodes of a said 2nd electrode is 50 micrometers or more and 300 micrometers or less. The electrode width of the first electrode is smaller than the thickness of the solder portion located between the first electrode and the second electrode in the obtained connection structure,
The electrode width of the second electrode is smaller than the thickness of the solder portion located between the first electrode and the second electrode in the obtained connection structure,
The interelectrode width of the first electrode is smaller than the thickness of the solder portion located between the first electrode and the second electrode in the obtained connection structure,
The interelectrode width of the second electrode is smaller than the thickness of the solder portion located between the first electrode and the second electrode in the obtained connection structure. The manufacturing method of the connection structure of any one of these.

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