JP2016058389A - Manufacturing method of connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a connection structure by which solder particles can be efficiently disposed between electrodes and conduction reliability between the electrodes can be improved.SOLUTION: The manufacturing method of a connection structure is subjected to a connection structure that is formed by laminating a first connection target member including at least one first electrode on a top face, a second connection target member including at least one second electrode on both a top face and a bottom face, and a third connection target member including at least one third electrode on a bottom face. Second conductive paste containing a thermally curable component and a plurality of solder particles is used for electrically connecting the second electrode and the third electrode. As the second connection target member, a second connection target member in which the second electrodes do not face each other on the top face and the bottom face of the second connection target member and positions of the second electrodes are displaced between the top face and the bottom face of the second connection target member is used.SELECTED DRAWING: Figure 1

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.

WO2008 / 023452A1

  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.

  In addition, as a new problem that is not described in Patent Document 1, using a conductive paste containing solder particles, connecting three or more connection target members, the electrodes on both sides of the connection target member located in the middle, When electrically connecting to the electrode on the upper surface of the connection target member positioned below and the electrode on the lower surface of the connection target member positioned above, the solder powder may not be efficiently collected between the electrodes. Found by the inventor.

  The objective of this invention is providing the manufacturing method of the connection structure which can arrange | position solder particles efficiently between electrodes and can improve the conduction | electrical_connection reliability between electrodes.

  According to a wide aspect of the present invention, using a second 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 upper surface, and at least A second connection object member having one second electrode on the upper surface and at least one second electrode on the lower surface is connected by a first connection portion containing conductive particles, Using a laminate in which the first electrode and the second electrode on the lower surface are electrically connected by a first conductive portion derived from the conductive particles, and at least one third electrode A step of disposing a second conductive paste layer using the second conductive paste on the upper surface of the second connection target member in the laminate using a third connection target member having a lower surface. And on the upper surface of the second conductive paste layer Arranging the third connection object member from the lower surface side so that the second electrode on the upper surface and the third electrode on the lower surface are opposed to each other; and the solder contained in the second conductive paste layer The second connection target member and the third connection target member are connected to each other by heating the second conductive paste layer above the melting point of the particles and above the curing temperature of the thermosetting component. 2 connecting portions are formed by the second conductive paste layer, and the second electrode on the upper surface and the third electrode on the lower surface are connected to the second solder portion in the second connecting portion. Electrically connecting the second electrode as the second connection target member on the upper surface and the lower surface of the second connection target member, the second connection not being opposed to the second connection target member. The position of the second electrode is shifted on the upper and lower surfaces of the target member. Using the connection object member, the manufacturing method of the connecting structure is provided.

  According to a wide aspect of the present invention, using a first conductive paste including a thermosetting component and a plurality of solder particles, using a second conductive paste including a thermosetting component and a plurality of solder particles. Second connection having at least one second electrode on the upper surface and at least one second electrode on the lower surface using the first connection target member having at least one first electrode on the upper surface The first conductive paste is applied on the upper surface of the first connection target member using the target member and the third connection target member having at least one third electrode on the lower surface. The first conductive paste layer is disposed on the top surface of the first conductive paste layer, and the second connection target member is disposed on the top surface of the first electrode on the top surface and the first electrode on the bottom surface. The step of arranging the two electrodes to face each other, and the front By heating the first conductive paste layer to a temperature equal to or higher than the melting point of the solder particles contained in the first conductive paste layer and equal to or higher than the curing temperature of the thermosetting component, the first connection target member and the second A first connecting portion that connects to the connection target member is formed of the first conductive paste layer, and the first electrode on the upper surface and the second electrode on the lower surface are connected to the first electrode A step of electrically connecting with a first solder portion in one connection portion, and a second conductive paste layer is disposed on the upper surface of the second connection target member using the second conductive paste And arranging the third connection target member on the upper surface of the second conductive paste layer so that the second electrode on the upper surface and the third electrode on the lower surface face each other from the lower surface side. And the solder grains contained in the second conductive paste layer The second connection target member and the third connection target member are connected by heating the second conductive paste layer to a temperature equal to or higher than the melting point of the thermosetting component and higher than the curing temperature of the thermosetting component. Are formed by the second conductive paste layer, and the second electrode on the upper surface and the third electrode on the lower surface are formed by the second solder portion in the second connection portion. Electrically connecting the second electrode as the second connection target member on the upper surface and the lower surface of the second connection target member, and the second connection target A method of manufacturing a connection structure is provided that uses a second connection target member in which the position of the second electrode is shifted between the upper surface and the lower surface of the member.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, when the second connection portion is formed of the second conductive paste layer, the heating of the second conductive paste layer is started. The time required to reach the melting point of the solder particles contained in the second conductive paste layer is set to 2 seconds or more and 60 seconds or less.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, in the step of disposing the third connection target member and the step of forming the third connection portion, no pressure is applied, and the second In the conductive paste layer, the weight of the third connection target member is added, or in at least one of the step of arranging the third connection target member and the step of forming the third connection portion The pressure of pressurization is less than 1 MPa in both the step of applying pressure and disposing the third connection target member and the step of forming the third connection portion.

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

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, when the first connection portion is formed of the first conductive paste layer, the heating of the first conductive paste layer is started. When the time to reach the melting point of the solder particles contained in the first conductive paste layer is 2 seconds or more and 60 seconds or less, and the second connection portion is formed by the second conductive paste layer. The time from the start of heating of the second conductive paste layer to the melting point of the solder particles contained in the second conductive paste layer is set to 2 seconds or more and 60 seconds 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 second connection portion, no pressure is applied, and the first In the conductive paste layer, the weight of the second connection target member is added, or at least one of the step of arranging the second connection target member and the step of forming the second connection portion The pressure of pressurization is less than 1 MPa in both the step of applying pressure and disposing the second connection target member and the step of forming the second connection part, and the third connection target In the step of arranging the member and the step of forming the third connection portion, no pressure is applied, and the weight of the third connection target member is added to the second conductive paste layer, or Step of arranging the third connection target member In at least one of the steps of forming the third connection portion, in both the step of applying pressure and arranging the third connection target member and the step of forming the third connection portion The pressure of pressurization is less than 1 MPa.

  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 first connection portion, no pressure is applied, and the first In the conductive paste layer, the weight of the second connection target member is added, and in the step of placing the third connection target member and the step of forming the second connection portion, no pressure is applied, The weight of the third connection target member is added to the second conductive paste layer.

  It is preferable that the average particle diameter of the solder particles contained in the second conductive paste is 0.5 μm or more and 100 μm or less. It is preferable that an average particle diameter of the solder particles contained in the first conductive paste is 0.5 μm or more and 100 μm or less. It is preferable that the content of the solder particles in the second conductive paste is 10% by weight or more and 80% by weight or less. It is preferable that the content of the solder particles in the first conductive paste is 10% by weight or more and 80% by weight or less.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, in the main surface direction of the second connection target member, the end portion of the second electrode on the upper surface of the second connection target member and the second connection target member The distance between the lower surface of the second connection target member and the end of the second electrode is 0 μm or more and 1000 μm or less.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, in the main surface direction of the second connection target member, the end portion of the second electrode on the upper surface of the second connection target member and the second connection target member The distance between the lower surface of the second connection target member and the end of the second electrode is 10 μm or more and 1000 μm or less.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, a said 3rd connection object member is a resin film, a flexible printed circuit board, a rigid flexible substrate, or a flexible flat cable.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, the second connection target member is a rigid substrate excluding a rigid flexible substrate, and the third connection target member is a resin film or a flexible print. It is a board | substrate, a rigid flexible board | 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 electrode width of the third 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, and the interelectrode width of the second electrode is 50 μm or more and 1000 μm or less, and the inter-electrode width of the third electrode is 50 μm or more and 1000 μm or less.

  In the manufacturing method of the connection structure according to the present invention, when the laminate is used, the second conductive paste is used on the upper surface of the second connection target member in the laminate. The step of disposing a paste layer and the second electrode on the upper surface and the third electrode on the lower surface are opposed to the third connection target member from the lower surface side on the upper surface of the second conductive paste layer. The second conductive paste layer is heated above the melting point of the solder particles contained in the second conductive paste layer and above the curing temperature of the thermosetting component. 2nd connection part which connects 2 connection object members and said 3rd connection object member is formed with said 2nd conductive paste layer, and said 2nd electrode of an upper surface and said above of a lower surface The third electrode is connected to the second electrode in the second connection portion. A step of electrically connecting with the second portion, and as the second connection target member, the second electrode is not opposed to the upper surface and the lower surface of the second connection target member, Since the second connection target member in which the position of the second electrode is shifted is used on the upper surface and the lower surface of the second connection target member, the solder particles can be efficiently arranged between the electrodes. It is possible to improve the reliability of conduction between the two.

  Moreover, the manufacturing method of the connection structure which concerns on this invention apply | coats the said 1st electrically conductive paste on the upper surface of said 1st connection object member, and arrange | positions a 1st electrically conductive paste layer, Disposing the second connection target member on the upper surface of the first conductive paste layer from the lower surface side so that the first electrode on the upper surface and the second electrode on the lower surface face each other; By heating the first conductive paste layer to a temperature equal to or higher than the melting point of the solder particles contained in the first conductive paste layer and equal to or higher than the curing temperature of the thermosetting component, the first connection target member and the second A first connecting portion that connects to the connection target member is formed of the first conductive paste layer, and the first electrode on the upper surface and the second electrode on the lower surface are connected to the first electrode. Electrically connecting with a first solder portion in one connecting portion; The step of disposing the second conductive paste layer on the upper surface of the second connection target member using the second conductive paste, and the third conductive paste layer on the upper surface of the second conductive paste layer. A step of disposing the connection target member from the lower surface side so that the second electrode on the upper surface and the third electrode on the lower surface are opposed to each other, and a melting point of the solder particles included in the second conductive paste layer or higher And the 2nd connection part which has connected the 2nd above-mentioned connection object member and the above-mentioned 3rd connection object member by heating the above-mentioned 2nd conductive paste layer above the curing temperature of the above-mentioned thermosetting ingredient. Are formed by the second conductive paste layer, and the second electrode on the upper surface and the third electrode on the lower surface are electrically connected by the second solder portion in the second connection portion. A step of connecting, and further as the second connection target member The second electrode is not opposed to the upper and lower surfaces of the second connection target member, and the position of the second electrode is shifted on the upper and lower surfaces of the second connection target member. Since 2 connection object members are used, the solder particles can be efficiently arranged between the electrodes, and the conduction reliability between the electrodes can be improved.

FIG. 1 is a partially cutaway front sectional view schematically showing a connection structure obtained by a method for manufacturing a connection structure according to an embodiment of the present invention. 2 (a) to 2 (c) are partially cutaway front cross-sectional views for explaining each step of the method for manufacturing a connection structure according to one embodiment of the present invention. 3A to 3C are partially cutaway front cross-sectional views for explaining each step of the method for manufacturing a connection structure according to one embodiment of the present invention. FIG. 4 is a partially cutaway front sectional view showing a modification of the connection structure. FIG. 5 is a partially cutaway front sectional view showing a conventional connection structure obtained by a conventional method for manufacturing a connection structure.

  Details of the present invention will be described below.

In a broad aspect of the present invention, in the method for manufacturing a connection structure according to the present invention,
(B) a second conductive paste containing a thermosetting component and a plurality of solder particles;
(A ′ / C ′ / D ′) a first connection target member having at least one first electrode on the upper surface, at least one second electrode on the upper surface, and at least one second electrode A second connection target member on the lower surface is connected by a first connection portion containing conductive particles, and the first electrode on the upper surface and the second electrode on the lower surface are connected to the conductive particles. A laminate that is electrically connected by the derived first conductive portion, and
(E) A third connection target member having at least one third electrode on the lower surface is used.

  In the present invention, when the second conductive paste (A) / (C ′ / D ′) and (E), the laminate, and the second connection target member are used, the second connection is performed. As the target member, the second electrode is not opposed to the upper surface and the lower surface of the second connection target member, and the position of the second electrode is the upper surface and the lower surface of the second connection target member. The shifted second connection target member is used.

The manufacturing method of the connection structure according to the present invention uses the second conductive paste, the laminate, and the second connection target member of (B), (A ′ / C ′ / D ′) and (E). In case,
(4th process) The process of arrange | positioning a 2nd electrically conductive paste layer using the said 2nd electrically conductive paste on the upper surface of the said 2nd connection object member in the said laminated body,
(Fifth Step) On the upper surface of the second conductive paste layer, the second electrode on the upper surface and the third electrode on the lower surface are opposed to the third connection target member from the lower surface side. A process of arranging in
(Sixth step) The second conductive paste layer is heated by heating the second conductive paste layer above the melting point of the solder particles contained in the second conductive paste layer and above the curing temperature of the thermosetting component. A second connection portion connecting the connection target member and the third connection target member is formed by the second conductive paste layer, and the second electrode on the upper surface and the third electrode on the lower surface are formed. Electrically connecting the electrodes of the second solder part in the second connection part,
Is provided.

  In the present invention, when the second conductive paste, the laminate, and the second connection target member of (B), (A ′ / C ′ / D ′) and (E) are used, the laminate is It may be obtained through the first, second, and third steps described later, or may not be obtained through the first, second, and third steps that will be described later.

Further, in a wide aspect of the present invention, a method for manufacturing a connection structure according to the present invention includes:
(A) a first conductive paste containing a thermosetting component and a plurality of solder particles;
(B) a second conductive paste containing a thermosetting component and a plurality of solder particles;
(C) a first connection target member having at least one first electrode on its upper surface;
(D) a second connection target member having at least one second electrode on the upper surface and at least one second electrode on the lower surface; and
(E) a third connection target member having at least one third electrode on the lower surface;
Is used.

  In the present invention, when the conductive paste and the connection target member of (A), (B), (C), (D), and (E) are used, the second connection target member is the second connection target member. The second connection target in which the second electrode is not opposed to the upper and lower surfaces of the connection target member, and the position of the second electrode is shifted on the upper and lower surfaces of the second connection target member. Use members.

The manufacturing method of the connection structure according to the present invention, when using the conductive paste and connection target member of the above (A), (B), (C), (D) and (E),
(First Step) A step of applying the first conductive paste on the upper surface of the first connection target member and disposing a first conductive paste layer;
(Second Step) On the upper surface of the first conductive paste layer, the first electrode on the upper surface and the second electrode on the lower surface are opposed to the second connection target member from the lower surface side. A process of arranging in
(Third step) The first conductive paste layer is heated to a temperature equal to or higher than the melting point of the solder particles contained in the first conductive paste layer and equal to or higher than the curing temperature of the thermosetting component. A first connecting portion connecting the connection target member and the second connection target member is formed by the first conductive paste layer, and the first electrode on the upper surface and the second electrode on the lower surface are formed. Electrically connecting the electrodes of the first solder portion in the first connection portion;
(Fourth Step) A step of disposing a second conductive paste layer on the upper surface of the second connection target member using the second conductive paste;
(Fifth Step) On the upper surface of the second conductive paste layer, the second electrode on the upper surface and the third electrode on the lower surface are opposed to the third connection target member from the lower surface side. A process of arranging in
(Sixth step) The second conductive paste layer is heated by heating the second conductive paste layer above the melting point of the solder particles contained in the second conductive paste layer and above the curing temperature of the thermosetting component. A second connection portion connecting the connection target member and the third connection target member is formed by the second conductive paste layer, and the second electrode on the upper surface and the third electrode on the lower surface are formed. Electrically connecting the electrodes of the second solder part in the second connection part,
Is provided.

  In the present invention, since the above-described configuration is provided, a plurality of solder particles easily gather between the electrodes, and the plurality of solder particles can be efficiently arranged on the electrodes (lines). In particular, a plurality of solder particles can be efficiently arranged between the second electrode on the upper surface and the third electrode on the lower surface. 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.

  Specifically, since the position of the second electrode is shifted between the upper surface and the lower surface of the second connection target member, heat is generated by the second electrode on the lower surface when the second conductive paste layer is thermally cured. Not dissipated. For this reason, the temperature of the second conductive paste layer between the second electrode on the upper surface and the third electrode on the lower surface can be sufficiently increased, and the melt viscosity of the second conductive paste layer is sufficiently decreased. The solder particles can be effectively collected between the second electrode on the upper surface and the third electrode on the lower surface.

  On the other hand, when the position of the second electrode is not shifted between the upper surface and the lower surface of the second connection target member, heat is dissipated by the second electrode on the lower surface when the second conductive paste layer is thermally cured. Is done. For this reason, the temperature of the second conductive paste layer between the second electrode on the upper surface and the third electrode on the lower surface is not sufficiently high, and the melt viscosity of the second conductive paste layer is not sufficiently low. The solder particles tend not to collect effectively between the second electrode on the upper surface and the third electrode on the lower surface.

  In the present invention, another method for efficiently collecting a plurality of solder particles between the electrodes may be further employed. As a method for efficiently collecting a plurality of solder particles between the electrodes, when heat is applied to the conductive paste between the connection target members, the convection of the conductive paste is generated by reducing the viscosity of the conductive paste by heat. Methods and the like. 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 by heat from the connection target member, and upper and lower connections Examples include a method of generating convection due to a temperature difference from the target member. Thereby, the solder particles in the conductive paste can be efficiently moved to the surface of the electrode.

  In the present invention, a method of selectively aggregating solder particles on the surface of the electrode may be further employed. As a method of selectively agglomerating solder particles on the surface of the electrode, there is a connection target member formed by an electrode material having good wettability of molten solder particles and another surface material having poor wettability of molten solder particles. A method of selectively adhering molten solder particles that have reached the surface of the electrode to the electrode and then melting and adhering another solder particle to the molten solder particles, and an electrode material with good thermal conductivity And other surface materials with poor thermal conductivity are selected, and when heat is applied, the temperature of the electrode is raised relative to the other surface members to selectively In this method, the solder particles are selectively agglomerated on the electrodes by using solder particles that have been treated so as to have a positive charge with respect to the negative charges existing on the electrode formed of metal. Method of, and, the electrode having a hydrophilic metal surface, the resin other than the solder particles in the conductive paste by a hydrophobic, a method to aggregate selectively solder particles on the electrode, and the like.

  The thickness of the solder part between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, preferably 150 μm or less, more preferably 80 μm or less. The solder wetted area on the surface of the electrode (area where the solder is in contact with 100% of the exposed area of the electrode) is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, preferably 100. % Or less.

  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 first connection portion, no pressure is applied, and the first conductive paste layer is formed. Pressurizes in at least one of the step of placing the second connection target member and the step of forming the first connection part when the weight of the second connection target member is added. And in both the process of arrange | positioning the said 2nd connection object member, and the process of forming the said 1st connection part, it is preferable that the pressure of pressurization is less than 1 MPa. By not applying a pressure of 1 MPa or more, the aggregation of solder particles is considerably promoted. From the viewpoint of suppressing warpage of the connection target member, in the method for manufacturing a connection structure according to the present invention, at least one of the step of arranging the second connection target member and the step of forming the first connection portion. The pressure of the pressurization may be less than 1 MPa in both the step of applying pressure and arranging the second connection target member and the step of forming the first connection portion. When performing pressurization, pressurization may be performed only in the step of arranging the second connection target member, or pressurization may be performed only in the step of forming the first connection portion, You may pressurize in both the process of arrange | positioning a said 2nd connection object member, and the process of forming a said 1st connection part. The case where the pressure is less than 1 MPa includes the case where no pressure is applied. When pressurizing, the pressure of pressurization is preferably 0.9 MPa or less, more preferably 0.8 MPa or less. When the pressure of the pressurization is 0.8 MPa or less, the aggregation of the solder particles is further promoted more remarkably than when the pressure of the pressurization exceeds 0.8 MPa.

  In the manufacturing method of the connection structure according to the present invention, in the step of arranging the third connection target member and the step of forming the second connection portion, no pressure is applied and the second conductive paste layer is formed. Pressurizes in at least one of the step of placing the third connection target member and the step of forming the second connection part when the weight of the third connection target member is added. And in both the process of arrange | positioning the said 3rd connection object member, and the process of forming the said 2nd connection part, it is preferable that the pressure of pressurization is less than 1 MPa. By not applying a pressure of 1 MPa or more, the aggregation of solder particles is considerably promoted. From the viewpoint of suppressing warpage of the connection target member, in the method for manufacturing a connection structure according to the present invention, at least one of the step of arranging the third connection target member and the step of forming the second connection portion. The pressure of the pressurization may be less than 1 MPa in both the step of applying pressure and arranging the third connection target member and the step of forming the second connection portion. When performing pressurization, pressurization may be performed only in the step of arranging the third connection target member, or pressurization may be performed only in the step of forming the second connection portion, You may pressurize in both the process of arrange | positioning a said 3rd connection object member, and the process of forming a said 2nd connection part. The case where the pressure is less than 1 MPa includes the case where no pressure is applied. When pressurizing, the pressure of pressurization is preferably 0.9 MPa or less, more preferably 0.8 MPa or less. When the pressure of the pressurization is 0.8 MPa or less, the aggregation of the solder particles is further promoted more remarkably than when the pressure of the pressurization exceeds 0.8 MPa.

  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 first connection portion, no pressure is applied, and the first conductive paste layer is formed. It is preferable that the weight of the second connection target member is added, and in the step of arranging the second connection target member and the step of forming the first connection portion, the first conductive paste layer includes It is preferable that no pressurized pressure exceeding the weight force of the second connection target member is applied. Further, in the step of disposing the third connection target member and the step of forming the second connection portion, no pressure is applied, and the second conductive paste layer is formed of the third connection target member. Preferably, weight is added, and in the step of arranging the third connection target member and the step of forming the second connection part, the second conductive paste layer has a weight of the third connection target member. It is preferable not to apply a pressurizing pressure exceeding that force. In these cases, the thickness of the solder portion can be increased more effectively, and a plurality of solder particles are likely to gather between the electrodes, and the plurality of solder particles are more efficiently collected on the electrodes (lines). Can be arranged. 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.

  In addition, it is necessary to use a conductive paste instead of a conductive film in order to efficiently arrange a plurality of solder particles on an electrode and to considerably reduce the amount of solder particles arranged in a region where no electrode is formed. The present inventor has found that

  Further, in the step of arranging the second connection target member and the step of forming the first connection portion, the weight of the second connection target member is applied to the first conductive paste layer without applying pressure. Is added, the solder particles arranged in the region (space) where the electrode is not formed before the connection portion is formed are more easily collected between the first electrode and the second electrode, and If the weight of the third connection target member is added to the second conductive paste layer without applying pressure in the step of arranging the connection target member of 3 and the step of forming the second connection part, Solder particles arranged in a region (space) where no electrode is formed before the connection portion is formed are more likely to gather between the first electrode and the second electrode, and the plurality of solder particles are separated from the electrode. More effective on line Also, the present inventors have found that it is possible to arranged. 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 first conductive paste layer without applying pressure, Alternatively, the effect of the present invention can be further improved by adopting the second conductive paste layer in combination with a configuration in which the weight of the third connection target member is added to the second conductive paste layer without applying pressure. It has great significance to get at a higher level.

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

  Moreover, if a conductive paste is used instead of a conductive film, it becomes easy to adjust the thickness of the connection part and the solder part depending on the amount of the conductive paste applied. On the other hand, in the conductive film, in order to change or adjust the thickness of the connection portion, it is necessary to prepare a conductive film having a different thickness or to prepare a conductive film having a predetermined thickness. There is. 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 includes a first connection target member 2, a second connection target member 3, a third connection target member 4, a first connection portion 5, and a second connection portion. 6.

  The first connection portion 5 connects the first connection target member 2 and the second connection target member 3. The first connection part 5 is formed of a first conductive paste containing a thermosetting component and a plurality of solder particles. The first connection portion 5 is a cured product of the first conductive paste. However, the 1st connection part 5 may be formed with the electrically-conductive material containing electroconductive particle, and this electroconductive particle may not be a solder particle. The conductive material may be a conductive paste, a conductive film, may not contain a thermosetting component, and may contain a thermoplastic component.

  The second connection portion 6 connects the second connection target member 3 and the third connection target member 4. The second connection portion 6 is formed of a second conductive paste containing a thermosetting component and a plurality of solder particles. The second connection portion 6 is a cured product of the second conductive paste.

  The first connection portion 5 includes a first solder portion 5A in which a plurality of solder particles gather and are joined to each other, and a first cured product portion 5B in which a thermosetting component is thermally cured. When the first connection portion is formed of a conductive material including a thermosetting component and a plurality of conductive particles, the first connection portion is a first conductive derived from the plurality of conductive particles. Part and the 1st hardened | cured material part by which the thermosetting component was thermosetted.

  The first connection target member 2 has a plurality of first electrodes 2a on the upper surface. The second connection target member 3 has a plurality of second electrodes 3a on the lower surface. The first electrode 2a on the upper surface and the second electrode 3a on the lower surface are electrically connected by the first solder portion 5A. Accordingly, the first connection target member 2 and the second connection target member 3 are electrically connected by the first solder portion 5A. In the first connecting portion 5, a region different from the first solder portion 5A gathered between the first electrode 2a on the upper surface and the second electrode 3a on the lower surface (first hardened material portion 5B portion) ) There is no solder. In a region different from the first solder portion 5A (first hardened product portion 5B portion), there is no solder separated from the first solder portion 5A. If the amount is small, solder is present in a region (first hardened material portion 5B portion) different from the first solder portion 5A gathered between the first electrode 2a and the second electrode 3a. It may be.

  The second connection portion 6 includes a second solder portion 6A in which a plurality of solder particles gather and are joined to each other, and a second cured product portion 6B in which a thermosetting component is thermally cured.

  The second connection target member 3 has a plurality of second electrodes 3b on the upper surface. The third connection target member 4 has a plurality of third electrodes 4a on the lower surface. The second electrode 3b on the upper surface and the third electrode 4a on the lower surface are electrically connected by the second solder portion 6A. Therefore, the second connection target member 3 and the third connection target member 4 are electrically connected by the second solder portion 6A. In the second connection portion 6, a region different from the second solder portion 6A collected between the second electrode 3b on the upper surface and the third electrode 4a on the lower surface (second cured product portion 6B portion) ) There is no solder. In a region different from the second solder portion 6A (second cured product portion 6B portion), there is no solder separated from the second solder portion 6A. If the amount is small, solder is present in a region (second cured product portion 6B portion) different from the second solder portion 6A gathered between the second electrode 3b and the third electrode 4a. It may be.

  As shown in FIG. 1, in the connection structure 1, a plurality of solder particles gather between the first electrode 2a on the upper surface and the second electrode 3a on the lower surface, and after the plurality of solder particles melt, After the particle melt wets and spreads on the surface of the electrode, it is solidified to form the first solder portion 5A. In the present embodiment, in the connection structure 1, the thickness of the first solder portion 5A located between the first electrode 2a on the upper surface and the second electrode 3a on the lower surface is the same as that of the first conductive paste. It is larger than the average particle diameter of the plurality of solder particles contained. For this reason, the contact area between the first solder part 5A and the first electrode 2a and between the first solder part 5A and the second electrode 3a is increased. By using the solder particles, the contact between the first solder portion 5A and the first electrode 2a is compared with the case where the conductive outer surface is made of a metal such as nickel, gold or copper. The area and the contact area between the first solder portion 5A and the second electrode 3a are increased. This also increases the conduction reliability and connection reliability in the connection structure 1.

  Further, as shown in FIG. 1, in the connection structure 1, after the plurality of solder particles are collected between the second electrode 3b on the upper surface and the third electrode 4a on the lower surface, the plurality of solder particles are melted. The second solder portion 6A is formed by solidifying the molten solder particles after wetting and spreading the surface of the electrode. In the present embodiment, in the connection structure 1, the thickness of the second solder portion 6A located between the second electrode 3b on the upper surface and the third electrode 4a on the lower surface is the same as that of the second conductive paste. It is larger than the average particle diameter of the plurality of solder particles contained. For this reason, the contact area between the second solder portion 6A and the second electrode 3b and between the second solder portion 6A and the third electrode 4a is increased. By using the solder particles, the contact between the second solder portion 6A and the second electrode 3b compared to the case where the conductive outer surface is made of a metal such as nickel, gold or copper. The area and the contact area between the second solder portion 6A and the third electrode 4a are increased. This also increases the conduction reliability and connection reliability in the connection structure 1.

  In addition, when a flux is included in the conductive paste, the flux is generally gradually deactivated by heating.

  Next, the manufacturing method of the connection structure which concerns on one Embodiment of this invention is demonstrated.

  First, a first conductive paste including a thermosetting component 11B and a plurality of solder particles 11A is prepared. Moreover, the 1st connection object member 2 which has the 1st electrode 2a on the upper surface is prepared.

  As shown in FIG. 2A, the first conductive paste layer 11 is disposed on the upper surface of the first connection target member 2 using the first conductive paste (first step). The first conductive paste layer 11 is disposed on the surface of the upper surface of the first connection target member 2 on which the first electrode 2a is provided. After the arrangement of the first conductive paste layer 11, the solder particles 11A are arranged both on the first electrode 2a (line) and on the region (space) where the first electrode 2a is not formed. Yes.

  The arrangement method of the first conductive paste layer 11 and the second conductive paste layer 12 to be described later is not particularly limited, and examples thereof include application by a dispenser, screen printing, and discharge by an inkjet apparatus.

  Further, a second connection target member 3 having the second electrode 3a on the lower surface and the second electrode 3b on the upper surface is prepared.

  Next, as shown in FIG. 2B, in the first conductive paste layer 11 on the upper surface of the first connection target member 2, the first connection target member 2 side of the first conductive paste layer 11 and Arrange | positions the 2nd connection object member 3 from the lower surface side on the surface (upper surface) of an other side (2nd process). On the upper surface of the first conductive paste layer 11, the second connection target member 3 is disposed from the lower electrode side of the second electrode 3a. At this time, the first electrode 2a on the upper surface and the second electrode 3a on the lower surface are opposed to each other.

  Next, the first conductive paste layer 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 first conductive paste layer 11 is heated to a temperature lower than the melting point of the solder particles 11A included in the first conductive paste layer 11 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 the present 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 first connection portion 5 connecting the first connection target member 2 and the second connection target member 3 is formed by the first conductive paste layer 11. Form. A first connection portion 5 is formed by the first conductive paste layer 11, a plurality of solder particles 11A are joined to form a first solder portion 5A, and the thermosetting component 11B is thermoset to form a first solder portion 5A. 1 cured product portion 5B is formed. If the solder particles 11A are sufficiently moved, the first electrode 2a and the second electrode are moved after the movement of the solder particles 11A not located between the first electrode 2a and the second electrode 3a starts. It is not necessary to keep the temperature constant until the movement of the solder particles 11A is completed.

  In addition, a second conductive paste including a thermosetting component 12B and a plurality of solder particles 12A is prepared.

  As shown in FIG. 3A, the second conductive paste layer 12 is disposed on the upper surface of the second connection target member 3 using the second conductive paste (fourth step). The second conductive paste layer 12 is disposed on the surface of the upper surface of the second connection target member 3 on which the second electrode 3b is provided. After the arrangement of the second conductive paste layer 12, the solder particles 12A are arranged both on the second electrode 3b (line) and on the region (space) where the second electrode 3b is not formed. Yes.

  Moreover, the 3rd connection object member 4 which has the 3rd electrode 4a in a lower surface is prepared.

  Next, as shown in FIG. 3B, in the second conductive paste layer 12 on the upper surface of the second connection target member 3, the second connection target member 3 side of the second conductive paste layer 12 and The third connection object member 4 is arranged from the lower surface side on the opposite surface (upper surface) (fifth step). On the upper surface of the second conductive paste layer 12, the third connection target member 4 is disposed from the lower electrode side of the third electrode 4a. At this time, the second electrode 3b on the upper surface is opposed to the third electrode 4a on the lower surface.

  Next, the second conductive paste layer 12 is heated above the melting point of the solder particles 12A included in the second conductive paste layer 12 and above the curing temperature of the thermosetting component 12B (sixth step). That is, the second conductive paste layer 12 is heated to a temperature lower than the melting point of the solder particles 12A and the curing temperature of the thermosetting component 12B. During this heating, the solder particles 12A that existed in the region where no electrode is formed gather between the second electrode 3b and the third electrode 4a (self-aggregation effect). In the present embodiment, since the conductive paste is used instead of the conductive film, the solder particles 12A are effectively collected between the second electrode 3b and the third electrode 4a. Also, the solder particles 12A are melted and joined together. Further, the thermosetting component 12B is thermoset. As a result, as shown in FIG. 3C, the second connection portion 6 connecting the second connection target member 3 and the third connection target member 4 is formed by the second conductive paste layer 12. Form. A second connecting portion 6 is formed by the second conductive paste layer 12, a plurality of solder particles 12A are joined to form a second solder portion 6A, and the thermosetting component 12B is thermally cured to form a second. 2 cured product portions 6B are formed. If the solder particles 12A are sufficiently moved, the second electrode 2b and the third electrode are started after the movement of the solder particles 12A that are not positioned between the second electrode 2b and the third electrode 4a starts. It is not necessary to keep the temperature constant until the movement of the solder particles 12A is completed between 4a and 4a.

  In the present embodiment, the amount of solder can be increased in the plurality of second solder portions 6A. This is because the second electrode 3a and the second electrode 3b are not opposed to each other on the upper surface and the lower surface of the second connection target member 3, and the second connection target member 3 has a second surface on the upper surface and the lower surface thereof. This is because the positions of the electrode 3a and the second electrode 3b are shifted. The second electrode 3a and the second electrode 3b are not opposed to each other through the second connection target member main body, and the second electrode 3a and the second electrode 3b are formed on the upper and lower surfaces of the second connection target member 3. The position of the second electrode 3b is shifted. There is no second electrode 3b on the upper surface above the second electrode 3a on the lower surface. There is no second electrode 3a on the lower surface below the second electrode 3b on the upper surface. For this reason, when the solder particles 12A on the second electrode 3b on the upper surface move by heating, heat is not easily dissipated below the second electrode 3b on the upper surface, and the viscosity of the second conductive paste layer 12 is sufficient. Easy to fall. As a result, the solder particles 12A move efficiently.

  Temporarily, the second electrodes 103a and 103b face each other on the upper and lower surfaces of the second connection target member 103, and the positions of the second electrodes 103a and 103b on the upper and lower surfaces of the second connection target member 103. If there is no deviation, it is easy to obtain a connection structure 101 as shown in FIG. The connection structure 101 includes a first connection target member 102, a second connection target member 103, a third connection target member 104, a first connection portion 105, and a second connection portion 106. . The first connection target member 102 has a plurality of first electrodes 102a on the upper surface. The second connection target member 103 has a plurality of second electrodes 103a on the lower surface and a plurality of second electrodes 103b on the upper surface. The third connection target member 104 has a plurality of third electrodes 104a on the lower surface. The first connection part 105 includes a first solder part 105A and a first cured product part 105B. The second connection portion 106 includes a second solder portion 106A and a first cured product portion 106B.

  When obtaining the connection structure 101, heat easily dissipates below the second electrode 103a on the upper surface when the solder particles on the second electrode 103a on the upper surface move by heating. Therefore, the temperature of the second conductive paste layer between the second electrode 103a on the upper surface and the third electrode 104a on the lower surface is not sufficiently high, and the melt viscosity of the second conductive paste layer is sufficiently low. In other words, it is difficult for the solder particles to effectively gather between the second electrode 103a on the upper surface and the third electrode 103b on the lower surface.

  In the main surface direction of the second connection target member, the end of the second electrode on the upper surface of the second connection target member and the end of the second electrode on the lower surface of the second connection target member The distance D (see FIG. 1) is 0 μm or more, preferably more than 0 μm, more preferably 0.1 μm or more, even more preferably 1 μm or more, still more preferably 3 μm or more, still more preferably 5 μm or more, and even more preferably It is 10 μm or more, still more preferably 50 μm or more, particularly preferably 100 μm or more, particularly preferably 150 μm or more, most preferably 200 μm or more, preferably 1000 μm or less. As the distance D is larger, heat dissipation by the second electrode on the lower surface can be further prevented. The main surface direction of the second connection target member is generally a direction orthogonal to the stacking direction of the first, second, and third connection target members in the obtained connection structure.

  In the connection structure 1 shown in FIG. 1, all of the first solder portion 5A is located in the facing region between the first and second electrodes 2a and 3a, and the second solder portion All of 6A is located in a region where the second and third electrodes 3b and 4a are opposed to each other. The connection structure 1X of the modification shown in FIG. 4 is different from the connection structure 1 shown in FIG. 1 only in the first and second connection portions 5X and 6X. The first and second connection portions 5X and 6X have first and second solder portions 5XA and 6XA and first and second hardened product portions 5XB and 6XB. As in the connection structure 1X, most of the first solder portions 5XA are located in regions where the first and second electrodes 2a and 3a are opposed to each other, and a part of the first solder portions 5XA is formed. You may protrude to the side from the area | region which the 1st, 2nd electrodes 2a and 3a oppose. The first solder part 5XA protruding laterally from the region where the first and second electrodes 2a and 3a are opposed to each other is a part of the first solder part 5XA, and from the first solder part 5XA It is not a remote solder. As in the connection structure 1X, most of the second solder part 6XA is located in a region where the second and third electrodes 3b and 4a are opposed to each other, and a part of the second solder part 6XA is formed. You may protrude to the side from the area | region which the 2nd, 3rd electrodes 3b and 4a oppose. The second solder portion 6XA protruding laterally from the region where the second and third electrodes 3b and 4a are opposed to each other is a part of the second solder portion 6XA, and from the second solder portion 6XA. It is not a remote solder. 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, it is easy to make the thickness of the solder portion located between the electrodes in the connection structure larger than the average particle diameter of the solder particles contained in the conductive paste.

  In the present embodiment, no pressure is applied in the second step and the third step, and no pressure is applied in the fifth step and the sixth step. In the present embodiment, the weight of the second connection target member 3 is added to the first conductive paste layer 11, and the weight of the third connection target member 4 is added to the second conductive paste layer 12. In this embodiment, a conductive paste is used instead of a conductive film. For this reason, when the first and second connection portions 5 and 6 are formed, the solder particles 11A are effectively gathered between the first electrode 2a and the second electrode 3a, and the solder particles 12A are Effectively gathers between the electrode 3b and the third electrode 4a. As a result, the thickness of the first solder portion 5A between the first electrode 2a and the second electrode 3a and the thickness of the second solder portion 6A between the second electrode 3b and the third electrode 4a. Tends to be thick. 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. If pressure is applied in at least one of the fifth step and the sixth step, the solder particles tend to collect between the second electrode and the third electrode. The tendency for the action to be inhibited increases. This has been found by the inventor.

  Moreover, in this embodiment, since pressurization is not performed, even when the connection target member is overlapped in a state where the alignment of the electrodes of the connection target member is shifted, the shift is corrected and the electrodes are connected. (Self-alignment effect). This is because the melted solder that self-aggregates between the electrodes is more energetically stable when the area where the solder between the electrodes and the other components of the conductive paste are in contact is minimized, so that the connection with the smallest area is possible. This is because the force to make the connection structure with alignment which is the structure works. 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 first conductive paste and the second 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 · s or more. If the viscosity is below a predetermined viscosity, the solder particles can be efficiently aggregated.If the viscosity is above a predetermined viscosity, the void at the joint is suppressed, and the protrusion of the conductive paste to other than the connection is suppressed. In addition, the uniformity of the solder amount can be further improved in the plurality of solder portions.

  In this way, the connection structure 1 shown in FIG. 1 is obtained. In addition, the said 2nd process and the said 3rd process may be performed continuously, and the said 5th process and 6th process may be performed continuously. In addition, after the second step, the first connection target member 2, the first conductive paste layer 11, and the second connection target member 3 are stacked and moved to the heating member. You may perform the said 3rd process. After performing the fifth step, the second connection target member 3, the second conductive paste layer 12, and the third connection target member 4 are stacked and moved to the heating member, Step 6 may be performed. 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 and the sixth step is not particularly limited as long as it is equal to or higher than the melting point of the solder particles included in the first and second conductive paste layers and equal to or higher 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.

  From the viewpoint of further promoting the movement of the solder particles and further improving the manufacturing efficiency of the connection structure, the first connection portion is formed by the first conductive paste layer when the first connection portion is formed. The time from the start of heating the conductive paste layer to the melting point of the solder particles contained in the first conductive paste layer is preferably 1 second or more, more preferably 2 seconds or more, preferably 300 seconds or less, more preferably Is 120 seconds or less, more preferably 60 seconds or less. This time is particularly preferably not less than 2 seconds and not more than 60 seconds.

  From the viewpoint of further promoting the movement of the solder particles and further improving the manufacturing efficiency of the connection structure, the second connection portion is formed by the second conductive paste layer when the second connection paste is formed. The time from the start of heating the conductive paste layer to the melting point of the solder particles contained in the second conductive paste layer is preferably 1 second or more, more preferably 2 seconds or more, preferably 300 seconds or less, more preferably Is 120 seconds or less, more preferably 60 seconds or less. This time is particularly preferably not less than 2 seconds and not more than 60 seconds.

  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. After the fifth step, the second connection target member or the third connection target member can be peeled off from the connection portion for the purpose of correcting the position and redoing the manufacture. The heating temperature for performing the peeling is preferably equal to or higher than the melting point of the solder particles, more preferably the melting point (° C.) of the solder particles in consideration of the melting points of the solder particles contained in the first and second conductive paste layers, respectively. + 10 ° C. or higher. 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 and the sixth step, the entire connection structure is heated using a reflow furnace or an oven above the melting point of the solder particles and the curing temperature of the thermosetting component. And a method of locally heating only the connection part of the connection structure.

  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.

  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 in each of an upper surface and a lower surface. The second connection target member preferably has a plurality of second electrodes on each of the upper surface and the lower surface. The third connection target member only needs to have at least one third electrode. The third connection object member preferably has a plurality of second electrodes.

  The said 1st, 2nd, 3rd connection object member is not specifically limited. Specific examples of the first, second, and third connection target members include semiconductor components, semiconductor packages, LED chips, LED packages, electronic components such as capacitors and diodes, resin films, printed boards, and flexible prints. Examples thereof include electronic parts such as circuit boards such as substrates, flexible flat cables, rigid flexible substrates, glass epoxy substrates and glass substrates. The first, second and third connection target members are preferably electronic components.

  It is preferable that at least one of the first connection target member, the second connection target member, and the third 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. The third 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 improved 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.

  It is preferable that the second connection target member is a rigid board excluding a rigid flexible board, and the third connection target member is a resin film, a flexible printed board, a rigid flexible board, or a flexible flat cable. If the second connection target member is a rigid substrate, the rigid substrate is hard, so that the second conductive paste can be arranged with high accuracy.

  Examples of the electrodes provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. 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 more efficiently arrange the solder particles on the electrode, the viscosity η at 25 ° C. of the first conductive paste and the second conductive paste is preferably 10 Pa · s or more, more preferably 50 Pa · s or more. More preferably, it is 100 Pa · s or more, preferably 800 Pa · s or less, more preferably 600 Pa · s or less, and further preferably 500 Pa · s or less.

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

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

  From the viewpoint of increasing the uniformity of the solder amount in the plurality of solder portions, the electrode width of the first electrode, the electrode width of the second electrode, and the electrode width of the third electrode are preferably 50 μm or more, More preferably, it is 75 micrometers or more, Preferably it is 1000 micrometers or less, More preferably, it is 500 micrometers or less, More preferably, it is 250 micrometers or less. The electrode width is the width of the line (L) in L / S. From the viewpoint of more efficiently arranging the solder particles between the electrodes, the interelectrode width of the first electrode, the interelectrode width of the second electrode, and the interelectrode width of the third electrode are preferably 50 μm. More preferably, it is 75 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, and still more preferably 250 μm or less. The inter-electrode width is the width of the space (S) in L / S. The effect of the present invention is more effectively exhibited as the electrode width and interelectrode width become smaller in the order of 100 μm or less, 85 μm or less, and 70 μm or less.

  The first conductive paste preferably includes a thermosetting component and a plurality of solder particles. The second 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 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. In the solder particles, both the central portion and the conductive outer surface are formed of solder. The solder particles are particles in which both the central portion and the conductive outer surface are solder.

  From the viewpoint of efficiently collecting the solder particles on the electrode, the zeta potential on the surface of the solder particles is preferably positive. However, in the present invention, the zeta potential of the surface of the solder particle may not be positive.

  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 10 mV or less, more preferably 5 mV or less, even more preferably 1 mV or less, still more preferably 0.7 mV or less, and particularly 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. The solder particles are preferably a surface treated product of an anion polymer or a compound that becomes an anion 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 —), a sulfonate ion group (—SO ₃ ^— ), And 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 metal (low melting point metal) having a melting point of 450 ° C. or lower. The solder particles are preferably metal particles (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, 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 size 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 100 μm or less, more preferably less than 80 μm, still more preferably 75 μm. Hereinafter, it is more preferably 60 μm or less, even more preferably 40 μm or less, still more preferably 30 μm or less, still 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 shape of the solder particles is not particularly limited. The solder particles may have a spherical shape or a shape other than a spherical shape such as a flat shape.

  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 are efficiently collected on the electrode, and the conduction reliability is further enhanced.

(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 above preferred epoxy compound, at the stage where the connection target members are bonded together, the viscosity is high, and when a shock such as transportation is applied to the acceleration, displacement of the connection target member can be suppressed. In addition, the viscosity of the conductive paste can be greatly reduced by heat during 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 imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents and other thiol curing agents, acid anhydrides, thermal cation initiators (thermal cation curing agents), and thermal radical generators. It is done. 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 thiol 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 thiol curing agent, or a latent amine curing agent. In addition, the said thermosetting agent may be coat | covered with polymeric substances, such as a polyurethane resin or a polyester resin.

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

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

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

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

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

  The reaction initiation temperature of the thermosetting agent is preferably 50 ° C or higher, more preferably 70 ° C or higher, still more preferably 80 ° C or higher, preferably 250 ° C or lower, more preferably 200 ° C or lower, still more preferably 150 ° C 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 activation temperature of the flux is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

  Examples of the flux having a melting point 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 heat is applied at the time of joining, when the electrode formed on the connection target member is compared with the portion of the connection target member around the electrode, the thermal conductivity of the electrode portion is Due to the fact that it is higher than the thermal conductivity, the temperature rise of the electrode part is quick. 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 initiator.

  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 a bisphenol F type epoxy resin (“EPICLON EXA-830CRP” manufactured by DIC) were placed in a three-necked flask and dissolved at 150 ° C. under a nitrogen flow. Thereafter, 0.1 part by weight of tetra-n-butylsulfonium bromide, which is an addition reaction catalyst for 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, whereby a reactant (polymer) A) was obtained.

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

Method for producing solder particles 1-3:
Solder particles having anionic polymer 1: 200 g of solder particle main 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 main 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 particle 1 (SnBi solder particle, melting point 139 ° C., solder particle body selected from “ST-3” manufactured by Mitsui Kinzoku Co., Ltd., surface treated anionic polymer 1 solder particle, 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)

  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 = 43 wt%: 57 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. Thus, a 1 μm thick copper layer is formed on the surface of the resin particles, and a 3 μm thick solder layer (tin: bismuth = 43 wt%: 57 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.)

(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.

(2) 1st connection structure It has 20 electrodes of the copper electrode pattern of electrode size 500 micrometers x 500 micrometers on the upper surface of a board | substrate so that the space between electrodes may be 1 mm, and electrode size 500 micrometers x 500 micrometers A glass epoxy substrate having 20 electrodes of a copper electrode pattern on the lower surface of the substrate was prepared so that the electrodes on the upper surface and the lower surface were alternately arranged at equal intervals. In the principal surface direction (direction orthogonal to the thickness direction) of the glass epoxy substrate, the distance D between the end of the upper electrode and the end of the lower electrode was 250 μm.

  In the glass epoxy substrate, the thickness of the copper electrode was 12 μm, the thickness of the solder resist was 30 μm, and the total thickness of the substrate was 0.6 mm.

  Next, prepare first and second flexible printed circuit boards (total thickness 100 μm) having 20 electrodes of a 500 μm × 500 μm copper electrode pattern on one surface so that the space between the electrodes is 1 mm. did.

  On the upper surface of the glass epoxy substrate, the anisotropic conductive paste immediately after fabrication 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 the first different paste is applied. An isotropic conductive paste layer was formed. Next, the first flexible printed circuit board was laminated on the upper surface of the first anisotropic conductive paste layer so that the electrodes face each other. At this time, no pressure was applied. The weight of the first flexible printed board is added to the first anisotropic conductive paste layer. Thereafter, the solder is melted while being heated on a hot plate so that the temperature of the first anisotropic conductive paste layer becomes 190 ° C., and the first anisotropic conductive paste layer is heated at 190 ° C. for 10 seconds. And cured to obtain a laminate.

  The obtained laminated body is inverted, and the anisotropic conductive paste immediately after the production is applied to the upper surface by screen printing using a metal mask so that the thickness is 100 μm on the electrode of the laminated body, A second anisotropic conductive paste layer was formed. Next, the second flexible printed circuit board was laminated on the upper surface of the second anisotropic conductive paste layer so that the electrodes face each other. At this time, no pressure was applied. The weight of the second flexible printed board is added to the second anisotropic conductive paste layer. Thereafter, the solder is melted while being heated on a hot plate so that the temperature of the second anisotropic conductive paste layer becomes 190 ° C., and the second anisotropic conductive paste layer is heated at 190 ° C. for 10 seconds. To obtain a first connection structure.

(Example 2)
20 electrodes of a copper electrode pattern with an electrode size of 500 μm × 500 μm are provided on the upper surface so that the space between the electrodes is 750 μm, and 20 electrodes of the copper electrode pattern with an electrode size of 500 μm × 500 μm are connected to the upper surface A glass epoxy substrate provided on the lower surface of the substrate was prepared so that the electrodes on the lower surface were alternately arranged at equal intervals. In the main surface direction (direction orthogonal to the thickness direction) of the glass epoxy substrate, the distance D between the end of the upper electrode and the end of the lower electrode was 125 μm.

  Next, prepare first and second flexible printed circuit boards (total thickness 100 μm) having 20 electrodes of a 500 μm × 500 μm copper electrode pattern on one surface so that the space between the electrodes is 750 μm did.

  A second connection structure was obtained in the same manner as the first connection structure of Example 1 except that the glass epoxy substrate and the first and second flexible printed boards were used.

(Example 3)
20 electrodes of a copper electrode pattern having an electrode size of 500 μm × 500 μm are provided on the upper surface so that a space between the electrodes is 500 μm, and 20 electrodes of a copper electrode pattern having an electrode size of 500 μm × 500 μm are connected to the upper surface A glass epoxy substrate provided on the lower surface of the substrate was prepared so that the electrodes on the lower surface were alternately arranged at equal intervals. In the main surface direction (direction orthogonal to the thickness direction) of the glass epoxy substrate, the distance D between the end of the upper electrode and the end of the lower electrode was 0 μm.

  Next, prepare first and second flexible printed circuit boards (total thickness 100 μm) having 20 electrodes of a copper electrode pattern of 500 μm × 500 μm on one side so that the space between the electrodes is 500 μm. did.

  A third connection structure was obtained in the same manner as the first connection structure of Example 1, except that the glass epoxy substrate and the first and second flexible printed boards were used.

Example 4
A first connection structure was obtained in the same manner as in Example 1 except that the blending component and blending amount of the anisotropic conductive paste were changed as shown in Table 1 below.

(Example 5)
A second connection structure was obtained in the same manner as in Example 2 except that the anisotropic conductive paste obtained in Example 4 was used.

(Example 6)
A third connection structure was obtained in the same manner as in Example 3 except that the anisotropic conductive paste obtained in Example 4 was used.

(Example 7)
A first connection structure was obtained in the same manner as in Example 1 except that a pressure of 1 Mpa was applied during heating of the second conductive paste layer.

(Example 8)
A first connection structure was obtained in the same manner as in Example 1 except that the blending component and blending amount of the anisotropic conductive paste were changed as shown in Table 1 below.

Example 9
A second connection structure was obtained in the same manner as in Example 2 except that the anisotropic conductive paste obtained in Example 8 was used.

(Example 10)
A third connection structure was obtained in the same manner as in Example 3 except that the anisotropic conductive paste obtained in Example 8 was used.

(Example 11)
20 electrodes of a copper electrode pattern with an electrode size of 500 μm × 500 μm are provided on the upper surface so that the space between the electrodes is 600 μm, and 20 electrodes of a copper electrode pattern with an electrode size of 500 μm × 500 μm are connected to the upper surface A glass epoxy substrate provided on the lower surface of the substrate was prepared so that the electrodes on the lower surface were alternately arranged at equal intervals. In the principal surface direction (direction orthogonal to the thickness direction) of the glass epoxy substrate, the distance D between the end of the upper electrode and the end of the lower electrode was 50 μm.

  Next, first and second flexible printed boards (total thickness 100 μm) having 20 electrodes of a copper electrode pattern of 500 μm × 500 μm on one side so that the space between the electrodes is 600 μm are prepared. did.

  A fourth connection structure was obtained in the same manner as the first connection structure of Example 1, except that the glass epoxy substrate and the first and second flexible printed boards were used.

Example 12
20 electrodes of a copper electrode pattern having an electrode size of 500 μm × 500 μm are provided on the upper surface so that a space between the electrodes is 520 μm, and 20 electrodes of a copper electrode pattern having an electrode size of 500 μm × 500 μm are connected to the upper surface A glass epoxy substrate provided on the lower surface of the substrate was prepared so that the electrodes on the lower surface were alternately arranged at equal intervals. In the main surface direction (direction orthogonal to the thickness direction) of the glass epoxy substrate, the distance D between the end of the upper electrode and the end of the lower electrode was 10 μm.

  Next, prepare first and second flexible printed circuit boards (total thickness 100 μm) having 20 electrodes of a copper electrode pattern of 500 μm × 500 μm on one side so that the space between the electrodes is 520 μm. did.

  A fifth connection structure was obtained in the same manner as the first connection structure of Example 1, except that the glass epoxy substrate and the first and second flexible printed boards were used.

(Example 13)
20 electrodes of a copper electrode pattern having an electrode size of 500 μm × 500 μm are provided on the upper surface of the substrate so that the space between the electrodes is 1 mm, and 20 electrodes of the copper electrode pattern having an electrode size of 500 μm × 500 μm are A flexible printed circuit board provided on the lower surface of the substrate was prepared so that the electrodes on the upper surface and the lower surface were alternately arranged at equal intervals. In the main surface direction (direction perpendicular to the thickness direction) of the flexible printed board, the distance D between the end of the upper electrode and the end of the lower electrode was 250 μm.

  In the flexible printed board, the thickness of the copper electrode was 12 μm, the thickness of the solder resist was 30 μm, and the total thickness of the board was 0.6 mm.

  A sixth connection structure was obtained in the same manner as in Example 1 except that the glass epoxy board was changed to a flexible printed board.

(Comparative Example 1)
The electrodes are opposite to each other on the upper and lower surfaces of the glass epoxy substrate, and the same as in Example 1 except that the electrodes are not displaced on the upper and lower surfaces of the first flexible printed circuit board. Thus, a seventh connection structure (electrode facing the glass epoxy substrate) was obtained.

(Comparative Example 2)
18 parts by weight of phenoxy resin (“YP-50S” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was dissolved in methyl ethyl ketone (MEK) so as to have a solid content of 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.

  A first connection structure was obtained in the same manner as in Example 1 except that the anisotropic conductive film was used.

(Comparative Example 3)
A first connection structure was obtained in the same manner as in Example 1 except that the blending component and blending amount of the anisotropic conductive paste were changed as shown in Table 1 below.

(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.

(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) Solder placement accuracy on the electrode In the cross-section (cross-section in the direction shown in FIG. 1) between the first and second flexible printed boards of the obtained connection structure, The area (%) of the solder remaining in the cured product away from the solder portion disposed therebetween 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]
○○: 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 ○ 1: 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 1% and 5% ○ 2: 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 5%, 10 % Or less Δ: 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 10%, 30 % Or less ×: 100% of the total area of solder appearing in the cross section, The area of the solder (solder particles) greater than 30% remaining in the cured product in away from the solder portion disposed to the machining gap

(4) 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 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]
○○: The average value of connection resistance is 50 mΩ or less ○ 1: The average value of connection resistance exceeds 50 mΩ and 60 mΩ or less ○ 2: The average value of connection resistance exceeds 60 mΩ and 70 mΩ or less △: The average value of connection resistance is 70 mΩ Exceeding 100 mΩ x: The average value of connection resistance exceeds 100 mΩ

(5) Insulation reliability between adjacent electrodes In the obtained first, second, and third connection structures (n = 15), 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 first and second flexible printed boards.

DESCRIPTION OF SYMBOLS 1,1X ... Connection structure 2 ... 1st connection object member 2a ... 1st electrode (upper surface side)
3 ... 2nd connection object member 3a ... 2nd electrode (lower surface side)
3b ... 2nd electrode (upper surface side)
4 ... 3rd connection object member 4a ... 3rd electrode (lower surface side)
5, 5X ... 1st connection part 5A, 5XA ... 1st solder part 5B, 5XB ... 1st hardened | cured material part 6, 6X ... 2nd connection part 6A, 6XA ... 2nd solder part 6B, 6XB ... 2nd hardened | cured material part 11 ... 1st electrically conductive paste layer 11A ... Solder particle 11B ... Thermosetting component 12 ... 2nd electrically conductive paste layer 12A ... Solder particle 12B ... Thermosetting component

Claims (17)

Using a second 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 top surface, and at least one second electrode on the top surface And a second connection target member having at least one second electrode on the lower surface is connected by a first connection portion containing conductive particles, and the first electrode on the upper surface and the first electrode on the lower surface A third connection object using a laminate in which the second electrode is electrically connected to the first conductive portion derived from the conductive particles and having at least one third electrode on the lower surface Using a member
A step of disposing a second conductive paste layer on the upper surface of the second connection target member in the laminate using the second conductive paste;
Arranging the third connection target member on the upper surface of the second conductive paste layer from the lower surface side so that the second electrode on the upper surface and the third electrode on the lower surface face each other;
By heating the second conductive paste layer above the melting point of the solder particles contained in the second conductive paste layer and above the curing temperature of the thermosetting component, the second connection target member and the first A second connection portion connecting the three connection target members with the second conductive paste layer, and the second electrode on the upper surface and the third electrode on the lower surface, Electrically connecting with a second solder part in the second connection part,
As the second connection target member, the second electrode is not opposed on the upper surface and the lower surface of the second connection target member, and the second connection target member is the second connection target member on the upper surface and lower surface of the second connection target member. The manufacturing method of a connection structure using the 2nd connection object member from which the position of the electrode of has shifted | deviated. Using a first conductive paste including a thermosetting component and a plurality of solder particles, and using a second conductive paste including a thermosetting component and a plurality of solder particles, at least one first electrode is formed. Using the first connection target member on the upper surface, using the second connection target member having at least one second electrode on the upper surface and at least one second electrode on the lower surface, and at least Using a third connection target member having one third electrode on the lower surface,
Applying the first conductive paste on the top surface of the first connection target member, and disposing a first conductive paste layer;
Disposing the second connection target member on the upper surface of the first conductive paste layer from the lower surface side so that the first electrode on the upper surface and the second electrode on the lower surface are opposed to each other;
By heating the first conductive paste layer above the melting point of the solder particles contained in the first conductive paste layer and above the curing temperature of the thermosetting component, the first connection object member and the first A first connection portion connecting the two connection target members with the first conductive paste layer, and the first electrode on the upper surface and the second electrode on the lower surface, Electrically connecting by a first solder part in the first connection part;
Disposing a second conductive paste layer on the upper surface of the second connection target member using the second conductive paste;
Arranging the third connection target member on the upper surface of the second conductive paste layer from the lower surface side so that the second electrode on the upper surface and the third electrode on the lower surface face each other;
By heating the second conductive paste layer above the melting point of the solder particles contained in the second conductive paste layer and above the curing temperature of the thermosetting component, the second connection target member and the first A second connection portion connecting the three connection target members with the second conductive paste layer, and the second electrode on the upper surface and the third electrode on the lower surface, Electrically connecting with a second solder part in the second connection part,
As the second connection target member, the second electrode is not opposed on the upper surface and the lower surface of the second connection target member, and the second connection target member is the second connection target member on the upper surface and lower surface of the second connection target member. The manufacturing method of a connection structure using the 2nd connection object member from which the position of the electrode of has shifted | deviated.   When the second connection portion is formed by the second conductive paste layer, from the start of heating of the second conductive paste layer until reaching the melting point of the solder particles contained in the second conductive paste layer The manufacturing method of the connection structure according to claim 1, wherein the time is set to 2 seconds or more and 60 seconds or less.   In the step of arranging the third connection target member and the step of forming the third connection portion, no pressure is applied, and the weight of the third connection target member is in the second conductive paste layer. Applying or applying pressure and disposing the third connection target member in at least one of the step of arranging the third connection target member and the step of forming the third connection part The manufacturing method of the connection structure of Claim 1 or 3 whose pressure of pressurization is less than 1 Mpa in both the process to form and the process of forming the said 3rd connection part.   In the step of arranging the third connection target member and the step of forming the second connection portion, no pressure is applied, and the weight of the third connection target member is in the second conductive paste layer. The manufacturing method of the connection structure of Claim 4 which adds. When the first connection portion is formed by the first conductive paste layer, from the start of heating of the first conductive paste layer to the melting point of the solder particles included in the first conductive paste layer Is set to 2 seconds or more and 60 seconds or less,
When the second connection portion is formed by the second conductive paste layer, from the start of heating of the second conductive paste layer until reaching the melting point of the solder particles contained in the second conductive paste layer The method for manufacturing a connection structure according to claim 2, wherein the time is set to 2 seconds or more and 60 seconds or less. In the step of arranging the second connection target member and the step of forming the second connection portion, no pressure is applied, and the weight of the second connection target member is in the first conductive paste layer. Applying or applying pressure and disposing the second connection target member in at least one of the step of arranging the second connection target member and the step of forming the second connection part In both the step of forming and the step of forming the second connection portion, the pressure of pressurization is less than 1 MPa,
In the step of arranging the third connection target member and the step of forming the third connection portion, no pressure is applied, and the weight of the third connection target member is in the second conductive paste layer. Applying or applying pressure and disposing the third connection target member in at least one of the step of arranging the third connection target member and the step of forming the third connection part The manufacturing method of the connection structure according to claim 2 or 6, wherein the pressure of pressurization is less than 1 MPa in both the step of forming and the step of forming the third connection portion. In the step of arranging the second connection target member and the step of forming the first connection part, no pressure is applied, and the weight of the second connection target member is in the first conductive paste layer. Join,
In the step of arranging the third connection target member and the step of forming the second connection portion, no pressure is applied, and the weight of the third connection target member is in the second conductive paste layer. The manufacturing method of the connection structure according to claim 7 to be added.   The method for manufacturing a connection structure according to any one of claims 1, 3, 4, and 5, wherein an average particle diameter of the solder particles contained in the second conductive paste is 0.5 µm or more and 100 µm or less. . The average particle diameter of the solder particles contained in the first conductive paste is 0.5 μm or more and 100 μm or less,
The method for producing a connection structure according to any one of claims 2, 6, 7, and 8, wherein an average particle diameter of the solder particles contained in the second conductive paste is 0.5 µm or more and 100 µm or less. .   10. The connection structure according to claim 1, wherein the content of the solder particles in the second conductive paste is 10 wt% or more and 80 wt% or less. Production method. The content of the solder particles in the first conductive paste is 10 wt% or more and 80 wt% or less,
11. The connection structure according to claim 2, wherein the content of the solder particles in the second conductive paste is 10% by weight or more and 80% by weight or less. Production method.   In the main surface direction of the second connection target member, an end of the second electrode on the upper surface of the second connection target member and an end of the second electrode on the lower surface of the second connection target member The method for manufacturing a connection structure according to any one of claims 1 to 12, wherein the distance is 0 μm or more and 1000 μm or less.   In the main surface direction of the second connection target member, an end of the second electrode on the upper surface of the second connection target member and an end of the second electrode on the lower surface of the second connection target member The method for manufacturing a connection structure according to claim 13, wherein the distance is 10 μm or more and 1000 μm or less.   The manufacturing method of the connection structure of any one of Claims 1-14 whose said 3rd connection object member is a resin film, a flexible printed circuit board, a rigid flexible substrate, or a flexible flat cable. The second connection target member is a rigid board excluding a rigid flexible board,
The manufacturing method of the connection structure of any one of Claims 1-15 whose said 3rd 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 electrode width of the third 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 interelectrode width of the second electrode is 50 μm or more and 1000 μm or less,
The method for manufacturing a connection structure according to any one of claims 1 to 16, wherein an inter-electrode width of the third electrode is 50 µm or more and 1000 µm or less.

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