JP2016076355A - Manufacturing method of connection structure, and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a connection structure capable of improving manufacture efficiency of the connection structure.SOLUTION: The manufacturing method of the connection structure includes the steps of: disposing a first conductive paste layer on a surface of one of a first connection object member and a second connection object member; disposing one of the second connection object member and the first connection object member on a surface of the first conductive paste layer; forming a first connection part connecting the first connection object member and the second connection object member from the first conductive paste layer by heating the first conductive paste layer, and electrically connecting a first conductor part and a second conductor part by a first solder part; and forming an inter-via connection conductor part communicating to a first via of the first connection object member and a second via of the second connection object member from a conductor material for inter-via connection.SELECTED DRAWING: Figure 1

Description

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

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

  In order to obtain various connection structures, the conductive material is, for example, a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), and 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 the electrode of the flexible printed circuit board and the electrode of the glass epoxy substrate are electrically connected by the conductive material, a conductive material containing conductive particles is disposed on the glass epoxy substrate. Next, a flexible printed circuit board is laminated, and heated and pressurized. As a result, the conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

  As an example of the 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 are present in the resin layer. An adhesive tape 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.

  On the other hand, conventionally, a build-up wiring board using a build-up method is known as a printed wiring board. In the build-up method, a build-up wiring board is obtained by repeating a lamination process, a via formation process, a wiring formation process, and the like.

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.

  Patent Document 1 describes using a substrate provided with vias. In this substrate, the via is filled with a conductive material in advance. When using a substrate filled with a conductive material in such a via, the cohesiveness of the solder differs between the electrode where the via is formed and the electrode where the via is formed. Since the connection resistance may vary, the manufacturing efficiency of the connection structure is poor.

  The objective of this invention is providing the manufacturing method of the connection structure which can improve the manufacture efficiency of a connection structure.

  According to a wide aspect of the present invention, the first conductive paste including the thermosetting component and the plurality of solder particles, the first connection target member having the first conductor portion, and the second conductor portion are included. The first conductive paste is formed on one surface of the first connection target member and the second connection target member using a second connection target member and a via-connecting conductive material. Applying and disposing the first conductive paste layer, and disposing one of the second connection target member and the first connection target member on the surface of the first conductive paste layer. And heating the first conductive paste layer to a temperature equal to or higher than the melting point of the solder particles and equal to or higher than the curing temperature of the thermosetting component, whereby the first connection target member and the second connection target member are The connecting first connecting portion is formed by the first conductive paste layer. And electrically connecting the first conductor portion and the second conductor portion with a first solder portion derived from the solder particles, and the first solder portion to A first via is formed in the first connection target member at a position different from a position where the first conductor portion and the second conductor portion are electrically connected, and the second connection A second via is formed in the target member, or after the step of forming the first connection portion, the first conductor portion and the second conductor portion are formed by the first solder portion. Forming a first via in the first connection target member and forming a second via in the second connection target member at a position different from the electrically connected position; An inter-via connection conductor portion connected to the via and the second via is formed of the inter-via connection conductor material. And a step of forming, method for manufacturing the connection structure is provided.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, the step of arranging one of the second connection target member and the first connection target member and the first connection portion are formed. In the process, pressure is not applied, and the weight of one of the second connection target member and the first connection target member is applied to the first conductive paste layer.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, the average particle diameter of the said solder particle in a said 1st electrically conductive paste is 0.5 micrometer or more and 100 micrometers or less.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, content of the said solder particle in a said 1st electrically conductive paste is 10 to 80 weight%.

  In a specific aspect of the manufacturing method of the connection structure according to the present invention, one of the second connection target member and the first connection target member arranged on the surface of the first conductive paste layer. Is a resin film, a flexible printed circuit board, a rigid flexible circuit board, or a flexible flat cable.

  On the specific situation with the manufacturing method of the connection structure which concerns on this invention, the 3rd connection object member which has a 2nd electrically conductive paste containing a thermosetting component and several electroconductive particle, and a 3rd conductor part. And applying the second conductive paste on the surface of the first connection target member opposite to the second connection target member side, and disposing the second conductive paste layer. And, on the surface of the second conductive paste layer, by placing the third connection target member, and by heating the second conductive paste layer above the curing temperature of the thermosetting component, The second connection portion connecting the second connection target member and the third connection target member is formed by the second conductive paste layer, and the first conductor portion and the first connection portion are formed. 3 are electrically connected to each other by a conductive portion derived from the conductive particles. And a process is provided.

  In a specific aspect of the manufacturing method of the connection structure according to the present invention, the conductive particles contained in the second conductive paste are solder particles, and the curing temperature of the thermosetting component is equal to or higher than the melting point of the solder particles. By heating the second conductive paste layer to a temperature higher than the temperature, the second connection portion connecting the first connection target member and the third connection target member is connected to the second conductive paste. A conductor formed by a paste layer, electrically connected to the first conductor portion and the third conductor portion by a second solder portion derived from the solder particles, and derived from the conductive particles The part is a second solder part derived from the solder particles.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, the first conductor portion and the third conductor portion are electrically connected by the second solder portion using a via-connecting conductor material. A first via is formed in the first connection target member and a third via is formed in the third connection target member at a position different from the position where the connection is established, or , After the step of forming the second connection portion, at a position different from the position where the first conductor portion and the third conductor portion are electrically connected by the second solder portion, An inter-via connection conductor that forms a first via in the first connection target member and forms a third via in the third connection target member and is continuous with the first via and the third via. A step of forming the portion with the via-connecting conductor material.

  According to a wide aspect of the present invention, a connection structure obtained by the above-described method for manufacturing a connection structure is provided.

  The method for manufacturing a connection structure according to the present invention includes a first conductive paste including a thermosetting component and a plurality of solder particles, a first connection target member having a first conductor portion, and a second conductor. The first connection target member and the second connection target member on the surface of the first connection target member by using the second connection target member having a portion and the via connecting conductor material. A step of applying a conductive paste and disposing a first conductive paste layer; and one of the second connection target member and the first connection target member on the surface of the first conductive paste layer. And heating the first conductive paste layer to a temperature equal to or higher than the melting point of the solder particles and equal to or higher than the curing temperature of the thermosetting component, whereby the first connection target member and the second connection target A first connecting portion connecting the member to the first conductive pace; Forming a layer and electrically connecting the first conductor portion and the second conductor portion with the first solder portion derived from the solder particles; and the first solder portion. A first via is formed in the first connection target member at a position different from a position where the first conductor portion and the second conductor portion are electrically connected, and the second conductor A second via is formed on the connection target member, or after the step of forming the first connection portion, the first conductor portion and the second conductor portion are formed by the first solder portion. Forming a first via in the first connection target member and forming a second via in the second connection target member at a position different from a position where the first connection target member is electrically connected, An inter-via connection conductor portion connected to one via and the second via is formed as the inter-via connection conductor. Since further comprising forming a charge, it is possible to greatly increase the production efficiency of the connection structure.

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 cross-sectional view for explaining each step of the manufacturing method of the connection structure according to one embodiment of the present invention. FIG. 5 is a partially cutaway front sectional view showing a modified example of the connection structure.

  Details of the present invention will be described below.

The manufacturing method of the 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 first connection target member having a first conductor portion;
(C) a second connection target member having a second conductor portion;
(D) a via-connecting conductor material;
Is used.

The manufacturing method of the connection structure according to the present invention includes:
(First Step) The first conductive paste is applied on one surface of the first connection target member and the second connection target member, and the first conductive paste layer is disposed. Process,
(Second Step) Arranging one of the second connection target member and the first connection target member on the surface of the first conductive paste layer;
(Third Step) The first connection target member and the second connection target are heated by heating the first conductive paste layer at a temperature equal to or higher than the melting point of the solder particles and equal to or higher than the curing temperature of the thermosetting component. A first connecting portion connecting the member is formed by the first conductive paste layer, and the first conductor portion and the second conductor portion are formed from the solder particles. Electrically connecting with one solder part;
(Fourth step) The first connection target member is placed at a position different from the position where the first conductor part and the second conductor part are electrically connected by the first solder part. The first via is formed and the second via is formed in the second connection target member, or after the step of forming the first connection portion, the first solder portion A first via is formed in the first connection object member at a position different from a position where the first conductor portion and the second conductor portion are electrically connected, and the second connection Forming a second via on the target member, and forming an inter-via connection conductor portion connected to the first via and the second via with the inter-via connection conductor material;
Is provided.

  In the second step, the connection target member to which the first conductive paste is not applied is disposed on the surface of the conductive paste layer. In the first step, when the first conductive paste layer is disposed on the surface of the first connection target member, the second connection target member is disposed on the surface of the first conductive paste layer. . In the first step, when the first conductive paste layer is disposed on the surface of the second connection target member, the first connection target member is disposed on the surface of the first conductive paste layer. .

  In this invention, since said structure is provided, the manufacturing efficiency of a connection structure can be improved. In the present invention, since the first conductor portion and the second conductor portion are formed by the first solder portion by the movement of the solder particles, the manufacturing efficiency of the connection structure is increased. Furthermore, since the solder cohesion between the electrodes is constant and the variation in connection resistance is reduced, the manufacturing efficiency of the connection structure is increased.

  Further, in the present invention, since the above-described configuration is provided, a plurality of solder particles are placed between the conductor portions (between the first conductor portion and the second conductor portion, the first conductor portion and the third conductor). And a plurality of solder particles can be efficiently arranged on the conductor part (line). Moreover, it is difficult for some of the plurality of solder particles to be disposed in a region (space) where the conductor portion is not formed, and the amount of solder particles disposed in the region where the conductor portion is not formed can be considerably reduced. . Therefore, the conduction reliability between the conductor portions can be increased. In addition, it is possible to prevent electrical connection between the conductor portions adjacent in the lateral direction that should not be connected, and to improve the insulation reliability.

  In the present invention, another method for efficiently collecting a plurality of solder particles between the conductor portions may be further employed. As a method for efficiently collecting a plurality of solder particles between conductor parts, when heat is applied to the conductive paste between the members to be connected, the convection of the conductive paste is generated by reducing the viscosity of the conductive paste by heat. And the like. In this method, a method of generating convection due to a difference in heat capacity between the conductor portion on the surface of the connection target member and other surface members, a method of generating convection as water vapor by heat from the connection target member, and upper and lower For example, a method of generating convection due to a temperature difference of the connection target members. Thereby, the solder particles in the conductive paste can be efficiently moved to the surface of the conductor portion.

Moreover, in a certain aspect of the manufacturing method of the connection structure according to the present invention,
(A) a first conductive paste containing a thermosetting component and a plurality of solder particles;
(B) a first connection target member having a first conductor portion;
(C) a second connection target member having a second conductor portion;
(D) a via-connecting conductor material;
(E) a second conductive paste containing a thermosetting component and a plurality of conductive particles;
(F) a third connection target member having a third conductor portion;
Is used.

When using the conductive paste and the connection target member of (A) to (F), the manufacturing method of the connection structure according to the present invention is as follows.
The first to fourth steps,
(Fifth Step) The second conductive paste layer is disposed by applying the second conductive paste on the surface of the first connection target member opposite to the second connection target member side. Process,
(Sixth step) The step of placing the third connection object member on the surface of the second conductive paste layer;
(7th process) The said 2nd connection object member and the said 3rd connection object member are connected by heating a said 2nd electrically conductive paste layer more than the curing temperature of the said thermosetting component. The second connection portion is formed by the second conductive paste layer, and the first conductor portion and the third conductor portion are electrically connected by the conductive portion derived from the conductive particles. And the process of
Is provided.

  The fourth step may be performed after the fifth to seventh steps.

  (Eighth step) The first connection object is located at a position different from the position where the first conductor part and the third conductor part are electrically connected by the second solder part. The first via is formed in the member and the third via is formed in the third connection target member, or after the step of forming the second connection portion, the second solder Forming a first via in the first connection target member at a position different from a position where the first conductor part and the third conductor part are electrically connected by the part, and the third Forming a third via in the connection target member, and forming an inter-via connection conductor portion connected to the first via and the third via with the inter-via connection conductor material. Also good.

  The fourth step and the eighth step may be performed separately or at the same time. The inter-via connection conductor material used in the fourth step and the eighth step may be the same or different.

  If a connection structure is produced through the first to eighth steps using the conductive paste, the connection target member, and the via-connecting conductive material of (A) to (F), a multi-layer connection structure can be obtained. . Further, the fourth, fifth,..., Nth connection target members having the fourth, fifth,.

  The first, second, and third conductor portions in the first, second, and third connection target members preferably function as electrodes.

  In the present invention, a method of selectively aggregating solder particles on the surface of the conductor portion may be further employed. As a method of selectively agglomerating solder particles on the surface of the conductor part, there is a connection formed by a conductor material having good wettability of molten solder particles and other surface material having poor wettability of molten solder particles. A method of selecting a target member, selectively adhering molten solder particles that have reached the surface of the conductor part to the conductor part, and then melting another solder particle to adhere to the molten solder particle, thermal conductivity By selecting a connection target member formed of a good conductor member quality and other surface material with poor thermal conductivity, and when applying heat, the temperature of the conductor part is made higher than other surface members , A method of selectively melting the solder on the conductor part, using the solder particles processed to have a positive charge with respect to the negative charge existing on the conductor part formed of metal, the conductor part Select The solder particles are selectively agglomerated in the conductor portion by making the resin other than the solder particles in the conductive paste hydrophobic with respect to the method of aggregating the solder particles and the conductor portion having a hydrophilic metal surface. And the like.

  The thickness of the solder portion between the conductor portions (between the first conductor portion and the second conductor portion, between the first conductor portion and the third conductor portion) is preferably 10 μm or more, more preferably It is 20 μm or more, preferably 100 μm or less, more preferably 80 μm or less. The solder wetted area on the surface of the conductor part (area where the solder in the exposed area of 100% of the conductor part is in contact) is preferably 50% or more, more preferably 70% or more, and preferably 100% or less.

  In the method for manufacturing a connection structure according to the present invention, pressure is applied in the step of arranging one of the second connection target member and the first connection target member and the step of forming the first connection portion. It is preferable that the weight of one of the second connection target member and the first connection target member is added to the first conductive paste layer, and the second connection target member and the above In the step of arranging one of the first connection target members and the step of forming the first connection part, the first conductive paste layer exceeds the force of the weight of the second connection target member. It is preferable that no pressure 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, it is possible to increase the thickness of the solder part more effectively, and it becomes easier for a plurality of solder particles to gather between the conductor parts, and the plurality of solder particles are more efficiently distributed on the conductor part (line). Can be arranged. Moreover, it is difficult for some of the plurality of solder particles to be disposed in a region (space) where the conductor portion is not formed, and the amount of solder particles disposed in the region where the conductor portion is not formed may be further reduced. it can. Therefore, the conduction reliability between the conductor portions can be further enhanced. In addition, electrical connection between laterally adjacent conductor portions that should not be connected can be further prevented, and insulation reliability can be further improved.

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

  Further, in the step of arranging one of the second connection target member and the first connection target member and the step of forming the first connection portion, no pressure is applied, and the first conductive paste is used. If the weight of one of the second connection target member and the first connection target member is added to the layer, the layer is arranged in a region (space) where the conductor portion is not formed before the connection portion is formed. The solder particles that have been collected are more likely to gather between the conductor portions, and in the step of arranging the third connection object member and the step of forming the second connection portion, no pressure is applied and the second conductive If the weight of the third connection object member is added to the paste layer, the solder particles arranged in the region (space) where the conductor portion is not formed before the connection portion is formed are more layered between the conductor portions. It ’s easier to get together, May be able to more efficiently disposed by I I via the or conductor portions particles (line) above, the present inventors have found. In the present invention, a configuration in which a conductive paste is used instead of a conductive film, and pressure is not applied, and the first conductive paste layer includes the second connection target member and the first connection target member. In combination with a configuration in which one of the weights of the third connection target is added, or a configuration in which the weight of the third connection target member is added to the second conductive paste layer without applying pressure. Employment has a great meaning in order to obtain the effect of the present invention at a higher level.

  In addition, WO2008 / 023452A1 describes that it is preferable to pressurize with a predetermined pressure at the time of bonding from the viewpoint of efficiently moving the solder powder to the surface of the electrode, and the pressurizing pressure further increases the solder area. From the viewpoint of reliably forming, for example, it is described that the pressure is 0 MPa or more, preferably 1 MPa or more. Further, even if the pressure intentionally applied to the adhesive tape is 0 MPa, the member arranged 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 and an inter-via connection conductor portion 7.

  The first connection target member 2 includes a first via 2b and a first conductor portion 2a. The first conductor portion 2a is not embedded in the first via 2b. The 1st conductor part 2a is arrange | positioned at the surface of the 1st connection object member 2 of the side by which the 2nd connection object member 3 is arrange | positioned. The first conductor portion 2a is also disposed on the surface of the first connection target member 2 on the side where the third connection target member 4 is disposed. There are a plurality of first vias 2b. There are also a plurality of first conductor portions 2a. There may be at least one first via and first conductor portion, and there may be no plural.

  The second connection target member 3 includes a second via 3b and a second conductor portion 3a. The second conductor portion 3a is not embedded in the second via 3b. The second conductor portion 3a is disposed on the surface of the second connection target member 3 on the side where the first connection target member 2 is disposed. The 2nd conductor part 3a is also arrange | positioned also on the surface of the 2nd connection object member 3 opposite to the side by which the 1st connection object member 2 is arrange | positioned. Another connection target member may be arranged on the opposite side of the second connection target member 3 from the first connection target member 2 side. There are a plurality of second vias 3b. There are also a plurality of second conductor portions 3a. There may be at least one second via and second conductor portion, and there may be no plural.

  The third connection target member 4 includes a third via 4b and a third conductor portion 4a. The third conductor portion 4a is not embedded in the third via 4b. The third conductor portion 4a is disposed on the surface of the third connection target member 4 on the side where the first connection target member 2 is disposed. The third conductor portion 4a is also disposed on the surface of the third connection target member 4 opposite to the side on which the first connection target member 2 is disposed. Another connection target member may be arranged on the side opposite to the first connection target member 2 side of the third connection target member 4. There are a plurality of third vias 4b. There are also a plurality of third conductor portions 4a. There may be at least one third via and third conductor portion, and there may be no plural. The third connection target member may not have the third via. The third connection target member preferably has a third conductor portion on the surface of the third connection target member on the side where the first connection target member is arranged. Further, the third connection target member is not necessarily used. The third conductor portion 4a may be a composite conductor layer having a layer covering the inner surface of the third via 4b and a filling portion filled in the layer.

  The first connection portion 5 connects the first connection target member 2 and the second connection target member 3. The 1st connection part 5 is formed with the electrically conductive paste containing a thermosetting component and several solder particle.

  The second connection portion 6 connects the first connection target member 2 and the third connection target member 4. The 2nd connection part 6 is formed with the electrically conductive paste containing a thermosetting component and several solder particle. However, the 2nd connection part 6 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 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.

  The first conductor portion 2a and the second conductor portion 3a 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 connection portion 5, in a region (first hardened product portion 5B portion) different from the first solder portion 5A gathered between the first conductor portion 2a and the second conductor portion 3a. 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, the solder is applied to a region (first hardened product portion 5B portion) different from the first solder portion 5A gathered between the first conductor portion 2a and the second conductor portion 3a. May be present.

  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. When the second connection portion is formed of a conductive material including a thermosetting component and a plurality of conductive particles, the second connection portion is a second conductive material derived from the plurality of conductive particles. Part and the 2nd hardened | cured material part by which the thermosetting component was thermosetted.

  The first conductor portion 2a and the third conductor portion 4a are electrically connected by the second solder portion 6A. Therefore, the first connection target member 2 and the third connection target member 4 are electrically connected by the second solder portion 6A. In the second connection portion 6, in a region (second cured product portion 6B portion) different from the second solder portion 6A gathered between the first conductor portion 2a and the third conductor portion 4a. 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, the solder is applied to a region (second cured product portion 6B portion) different from the second solder portion 6A gathered between the first conductor portion 2a and the third conductor portion 4a. May be present.

  As shown in FIG. 1, in the connection structure 1, a plurality of solder particles gather between the first conductor portion 2 a and the second conductor portion 3 a, and after the plurality of solder particles melt, The molten material wets and spreads on the surface of the conductor portion and then solidifies to form the first solder portion 5A. In the present embodiment, the thickness of the first solder portion 5A located between the first conductor portion 2a and the second conductor portion 3a in the connection structure 1 is included in the first conductive paste. It is larger than the average particle diameter of the plurality of solder particles. For this reason, the connection area of 5 A of 1st solder parts and the 1st conductor part 2a and 5 A of 1st solder parts, and the 2nd conductor part 3a becomes large. By using the solder particles, the first solder portion 5A and the first conductor portion 2a, as compared with the case where the conductive outer surface is made of a metal such as nickel, gold or copper, is used. The contact area between the first solder portion 5A and the second conductor portion 3a is 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, a plurality of solder particles gather between the first conductor portion 2a and the third conductor portion 4a, and after the plurality of solder particles melt, The melt of particles wets and spreads the surface of the conductor portion, and then solidifies to form the second solder portion 6A. In the present embodiment, the thickness of the second solder portion 6A located between the first conductor portion 2a and the third conductor portion 4a in the connection structure 1 is included in the second conductive paste. It is preferably larger than the average particle diameter of the plurality of solder particles. In this case, the connection area between the second solder portion 6A and the first conductor portion 2a and between the second solder portion 6A and the third conductor portion 4a is increased. By using the solder particles, the second solder portion 6A and the first conductor portion 2a, as compared with the case where the conductive outer surface is made of a metal such as nickel, gold, or copper, is used. The contact area between the second solder portion 6A and the third conductor portion 4a is increased. This also increases the conduction reliability and connection reliability in the connection structure 1.

  The inter-via connection conductor 7 is connected via the first via 2b and the second via 3b. Further, the inter-via connection conductor portion 7 is connected via the first via 2b and the third via 4b. The inter-via connection conductor 7 includes an outer surface opposite to the first connection target member 2 side of the second connection target member 3, and the first connection target member 2 side of the third connection target member 4. Leads to the opposite outer surface. The inter-via connection conductor portion 7 is disposed at a position different from the position where the first conductor portion 2a and the second conductor portion 3a are electrically connected by the first solder portion 5A. The first conductor portion 2a and the third conductor portion 4a are disposed at a position different from the position where the first conductor portion 2a and the third conductor portion 4a are electrically connected by the solder portion 6A. The via connection conductor part 7, the first conductor part 2a, and the second conductor part 3a are not electrically connected. The via connection conductor part 7, the first conductor part 2a, and the third conductor part 4a are not conductive.

  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 using FIG. 2 (a)-(c), FIG. 3 (a)-(c), and FIG.

  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 conductor part 2a is prepared. At this time, the first via 2 a is not formed in the first connection target member 2. At this time, the first via 2 a may be formed in the first connection target member 2.

  As shown in FIG. 2A, the first conductive paste layer 11 is disposed on the surface of the first connection target member 2 using the first conductive paste (first step). You may arrange | position a 1st conductive paste layer on the surface of a 2nd connection object member using the said 1st conductive paste. In this case, the second connection target member does not necessarily have a via. The first conductive paste layer 11 is disposed on the surface of the first connection target member 2 on which the first conductor portion 2a is provided. After the arrangement of the first conductive paste layer 11, the solder particles 11A are arranged both on the first conductor portion 2a (line) and on the region (space) where the first conductor portion 2a is not formed. Has been.

  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.

  Moreover, the 2nd connection object member 3 which has the 2nd conductor part 3a is prepared. At this time, the second via 3 b is not formed in the second connection target member 3. At this time, the second via 3 b may be formed in the second connection target member 3.

  Next, as shown in FIG. 2 (b), in the first conductive paste layer 11 on the 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 on the surface (upper surface) on the opposite side (2nd process). At this time, it is preferable that the first conductor portion 2a and the second conductor portion 3a face each other. When the first conductive paste layer is disposed on the surface of the second connection target member, the first connection target member is disposed on the surface of the first conductive paste layer.

  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 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 the electrode is not formed gather between the first conductor portion 2a and the second conductor portion 3a (self-aggregation effect). In this embodiment, since the conductive paste is used instead of the conductive film, the solder particles 11A are effectively collected between the first conductor portion 2a and the second conductor portion 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. The first solder portion 5A is derived from the solder particles 11A. The first conductor portion 2a and the second conductor portion 3a are electrically connected by the first solder portion 5A.

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

  As shown to Fig.3 (a), the 2nd conductive paste layer 12 is arrange | positioned on the surface of the 1st connection object member 2 using the said 2nd conductive paste (5th process). In addition, in Fig.3 (a), the laminated body is reversed from the state shown in FIG.2 (c). The second conductive paste layer 12 is disposed on the surface of the first connection target member 2 on which the first conductor portion 2a is provided. After the arrangement of the second conductive paste layer 12, the solder particles 12A are arranged both on the first conductor portion 2a (line) and on the region (space) where the first conductor portion 2a is not formed. Has been.

  Moreover, the 3rd connection object member 4 which has the 3rd conductor part 4a is prepared. At this time, the third via 4 a is not formed in the third connection target member 4. At this time, the third via 4 a may be formed in the third connection target member 4.

  Next, as shown in FIG. 3B, in the second conductive paste layer 12 on the surface of the first connection target member 2, the first connection target member 2 side of the second conductive paste layer 12 and Arranges the third connection target member 4 on the opposite surface (upper surface) (sixth step). At this time, it is preferable that the first conductor portion 2a and the third conductor portion 4a face each other.

  Next, the second conductive paste layer 12 is heated above the melting point of the solder particles 12A and above the curing temperature of the thermosetting component 12B (seventh 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. At the time of this heating, the solder particles 12A that existed in the region where the conductor portion is not formed gather between the first conductor portion 2a and the third conductor portion 4a (self-aggregation effect). In this embodiment, since the conductive paste is used instead of the conductive film, the solder particles 12A are effectively collected between the first conductor portion 2a and the third conductor portion 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 first connection target member 2 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. The second solder portion 6A is derived from the solder particles 12A. The first conductor portion 2a and the third conductor portion 4a are electrically connected by the second solder portion 6A.

  In the connection structure 1 shown in FIG. 1, all of the first solder portions 5A are located in the facing region between the first and second conductor portions 2a and 3a, and the second solder All of the portion 6A is located in a region where the first and third conductor portions 2a and 4a are opposed to each other. Although the connection structure 1X of the modification shown in FIG. 5 has the 2nd conductor part 3Xa in the side by which the 1st connection object member 2 is arrange | positioned, what is the side by which the 1st connection object member 2 is arrange | positioned? The second connection target member 3X that does not have the second conductor portion on the opposite side is used, and the first connection target member 2 has the third conductor portion 4Xa on the side where the first connection target member 2 is disposed. The third connection target member 4X that does not have the third conductor portion on the side opposite to the side on which the connection target member 2 is disposed is used. First, second, and third vias 2b, 3Xb, and 4Xb are formed in the first, second, and third connection target members 2, 3X, and 4X. An inter-via connection conductor 7 is formed in the first, second, and third vias 2b, 3Xb, and 4Xb so as to be continuous. The connection structure 1X of the modification shown in FIG. 5 is different from the connection structure 1 shown in FIG. 1 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 parts 5XA are located in regions where the first and second conductor parts 2a and 3Xa are opposed to each other, and a part of the first solder part 5XA However, you may protrude to the side from the area | region which the 1st, 2nd conductor parts 2a and 3Xa oppose. The first solder portion 5XA protruding laterally from the region where the first and second conductor portions 2a and 3Xa are opposed to each other is a part of the first solder portion 5XA, and the first solder portion 5XA. Solder away from. As in the connection structure 1X, most of the second solder portion 6XA is located in a region where the first and third conductor portions 2a and 4Xa face each other, and a part of the second solder portion 6XA. However, you may protrude to the side from the area | region which the 1st, 3rd conductor parts 2a and 4Xa oppose. The second solder portion 6XA protruding laterally from the region where the first and third conductor portions 2a, 4Xa are opposed to each other is a part of the second solder portion 6XA, and the second solder portion 6XA. Solder away from. 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 sixth step and the seventh step. In the present embodiment, the weight of the second connection target member 3 (one of the second connection target member 3 and the first connection target member 2) is added to the first conductive paste layer 11, and the second The weight of the third connection object member 4 is added to the conductive paste layer 12. In this embodiment, a conductive paste is used instead of a conductive film. For this reason, at the time of forming the first and second connection portions 5 and 6, the solder particles 11A are effectively gathered between the first conductor portion 2a and the second conductor portion 3a, and the solder particles 12A are It effectively gathers between the first conductor part 2a and the third conductor part 4a. As a result, the thickness of the first solder portion 5A between the first conductor portion 2a and the second conductor portion 3a and the second solder between the first conductor portion 2a and the third conductor portion 4a. The thickness of the part 6A tends to be thick. In addition, if pressurization is performed in at least one of the second step and the third step, the solder particles may be disposed between the first conductor portion and the second conductor portion or between the first and second conductor portions. The tendency to inhibit the action of collecting in the via is increased, and if pressurization is performed in at least one of the sixth step and the seventh step, the solder particles are separated from the second conductor portion. The tendency to hinder the action of gathering with the third conductor portion is increased. 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 conductor part of the connection target member is shifted, the shift is corrected and the gap between the conductor parts is corrected. Can be connected (self-alignment effect). This is because the molten solder that self-aggregates between the conductor parts becomes more stable in terms of energy when the area where the solder between the conductor parts and the other components of the conductive paste are in contact is minimized. This is because the force to make the connection structure with alignment, which is the connection structure, is obtained. 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 the predetermined viscosity, the void at the connection portion is suppressed, and the conductive paste is prevented from protruding beyond the connection portion. In addition, the uniformity of the solder amount can be further improved in the plurality of solder portions.

  Also, a conductor material for connecting vias is prepared.

  As shown in FIG. 4, after the step of forming the first connection portion 5 and the step of forming the second connection portion 6, the first conductor portion 2a and the second conductor portion are formed by the first solder portion 5A. The first via 2b is formed in the first connection target member 2 and the second via 3b is formed in the second connection target member 3 at a position different from the position where the 3a is electrically connected. Then, the inter-via connection conductor 7 connected to the first via 2b and the second via 3b is formed of the inter-via connection conductor material (fourth step). Simultaneously with the fourth step, the first connection target member is located at a position different from the position where the first conductor portion 2a and the third conductor portion 4a are electrically connected by the second solder portion 6A. The first via 2b is formed in 2 and the third via 4b is formed in the third connection target member 4, and the inter-via connecting conductor portion 7 connected to the first via 2b and the third via 4b is formed. The via-connecting conductor material is used (fourth step and eighth step).

  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 6th process and 7th 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 unit. You may perform the said 3rd process. After performing the sixth step, the first connection target member 2, the second conductive paste layer 12, and the third connection target member 4 are stacked and moved to the heating unit. You may perform the process of 7. 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 seventh step is not particularly limited as long as it is not lower than the melting point of the solder particles and not lower than the curing temperature of the thermosetting component. The heating temperature is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, preferably 450 ° C. or lower, more preferably 250 ° C. or lower, and still more preferably 200 ° C. or lower.

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

  As a heating method in the third step and the seventh 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 locally heating with a hot plate, the part 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.

  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. One of the second connection target member and the first connection target member (connection target member disposed on the surface of the first conductive paste layer) is a resin film, a flexible printed circuit board, or a flexible flat cable. Or it is preferable that it is a rigid flexible substrate. 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 a conductor part easily. On the other hand, even if a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board is used, the conduction reliability between the conductor parts is sufficiently enhanced by efficiently collecting the solder particles on the conductor parts. be able to. 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 conductor parts by not applying pressure compared to the case of using other connection target members such as a semiconductor chip Can be more effectively obtained.

  As an electrode which is a conductor part which can be provided in the said connection object member, metal electrodes, such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, and a tungsten electrode, are mentioned. 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.

  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 conductive 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 conductor portion and further reducing the connection resistance, the conductive paste preferably contains a flux.

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

(Conductive particles and solder particles)
Examples of the conductive particles include conductive particles formed entirely of a conductive material, and conductive particles having base material particles and a conductive layer disposed on the surface of the base material particles. It is done.

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

  From the viewpoint of efficiently collecting the solder particles on the conductor portion, it is preferable that the zeta potential on the surface of the solder particles is 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 0 mV or more, more preferably more than 0 mV, preferably 1 mV or less, more preferably 0.7 mV or less, and even more preferably 0.5 mV or less. When the zeta potential is less than or equal to the above upper limit, the solder particles hardly aggregate in the conductive paste before use. When the zeta potential is 0 mV or more, the solder particles efficiently aggregate on the conductor portion during mounting.

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

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

Examples of the anion portion of the anion polymer include the carboxyl group, and other than that, a tosyl group (p-H ₃ CC ₆ H ₄ S (═O) ₂ —), 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. Examples of the functional group that polymerizes by addition and condensation reactions include a hydroxyl group, a carboxyl group, an amino group, and (meth). An acryloyl group is mentioned.

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

  When the weight average molecular weight is not less than the above lower limit and not more than the above upper limit, 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 more efficiently on the conductor portion.

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

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

  The solder is preferably a low melting point metal having a melting point of 450 ° C. or lower. The solder particles are preferably low melting point metal particles having a melting point of 450 ° C. or lower. The low melting point metal particles are particles containing a low melting point metal. The low melting point metal is a metal having a melting point of 450 ° C. or lower. The melting point of the low melting point metal is preferably 300 ° C. or lower, more preferably 160 ° C. or lower. The solder particles include tin. In 100% by weight of the metal contained in the solder particles, the content of tin is preferably 30% by weight or more, more preferably 40% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the content of tin in the solder particles is not less than the above lower limit, the connection reliability between the solder portion and the conductor portion 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 conductor portion, and the solder portion conducts between the conductor portions. For example, since the solder portion and the conductor portion are likely to be in surface contact rather than point contact, the connection resistance is lowered. Also, the use of solder particles increases the bonding strength between the solder part and the conductor part. As a result, peeling between the solder part and the conductor part 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 a conductor part, it is preferable that the said low melting metal is a tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, and a tin-indium alloy. More preferred are a tin-bismuth alloy and a tin-indium alloy.

  The solder particles are preferably a filler material having a liquidus line of 450 ° C. or lower based on JIS Z3001: welding terms. Examples of the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. Among them, a tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic) which is low-melting and lead-free is preferable. That is, the solder particles preferably do not contain lead, and preferably contain tin and indium, or contain tin and bismuth.

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

  The average particle diameter of the solder particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more, particularly preferably 5 μm or more, preferably 100 μm or less, more preferably 40 μm or less, and even more preferably 30 μm. Hereinafter, it is more preferably 20 μm or less, particularly preferably 15 μm or less, and most preferably 10 μm or less. When the average particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently arranged on the conductor portion. 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 conductor portion. 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

  In 100% by weight of the conductive paste, the content of the conductive particles and the content of the solder particles are preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, and particularly preferably 20%. % By weight or more, 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 conductive particles and the content of the solder particles are not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the conductor portion, and the solder particles are disposed between the conductor portions. It is easy to dispose a large number of and the conduction reliability is further enhanced. From the viewpoint of further improving the conduction reliability, it is preferable that the content of the solder particles is large.

  In particular, the content of the solder particles in 100% by weight of the conductive paste is preferably 1% by weight or more, and preferably 80% by weight or less. In this case, solder particles efficiently gather on the conductor portion, 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 an imidazole curing agent, an amine curing agent, a phenol curing agent, a polythiol curing agent, an acid anhydride, a thermal cation initiator, and a thermal radical generator. As for the said thermosetting agent, only 1 type may be used and 2 or more types may be used together.

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

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

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

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

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

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

  The reaction initiation temperature of the thermosetting agent is preferably 50 ° C or higher, more preferably 70 ° C or higher, still more preferably 80 ° C or higher, preferably 250 ° C or lower, more preferably 200 ° C or lower, still more preferably 150 ° C or lower, Especially preferably, it is 140 degrees C or less. When the reaction start temperature of the thermosetting agent is not less than the above lower limit and not more than the above upper limit, the solder particles are more efficiently arranged on the conductor portion. 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 conductor part, 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, it is 10 ° C. or higher.

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

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent 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 the flux, the solder can be arranged more effectively on the conductor portion. 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 and pine resin, the conduction reliability between the conductor portions 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 conductor portions 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 conductor portion. 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 conductor portion, 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. More preferably.

  From the viewpoint of more efficiently arranging the solder on the conductor portion, 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, it is high.

  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 conductor portion. This is because when heat is applied at the time of joining, when the conductor part formed on the connection target member is compared with the part of the connection target member around the conductor part, the thermal conductivity of the conductor part part is the connection around the conductor part. This is due to the fact that the temperature of the conductor portion is fast because it is higher than the heat traditional rate of the target member portion. 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 conductor portion first reaches the melting point (activation temperature) of the flux, the oxide film on the surface of the solder particles that has come preferentially on the conductor portion is removed, and the solder particles are removed from the conductor portion. Can spread on the surface. Thereby, solder particles can be efficiently aggregated on the conductor part.

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

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

  In 100% by weight of the conductive paste, the content of the flux is preferably 0.5% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. The conductive paste may not contain a flux. When the content of the flux is not less than the above lower limit and not more than the above upper limit, an oxide film is more difficult to be formed on the surface of the solder and the conductor part, and further, the oxide film formed on the surface of the solder and the conductor part is further reduced. Can be effectively 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:
(1) Synthesis of reaction product (polymer A) of bisphenol F with 1,6-hexanediol diglycidyl ether and bisphenol F type epoxy resin:
Bisphenol F (containing 4,4′-methylene bisphenol, 2,4′-methylene bisphenol and 2,2′-methylene bisphenol in a weight ratio of 2: 3: 1) 100 parts by weight, 1,6-hexanediol Three parts: 130 parts by weight of glycidyl ether, 5 parts by weight of bisphenol F type epoxy resin (“EPICLON EXA-830CRP” manufactured by DIC), and 10 parts by weight of resorcinol type epoxy compound (“EX-201” manufactured by Nagase ChemteX) It put into the neck flask and it was made to melt | dissolve at 100 degreeC under nitrogen flow. Thereafter, 0.15 part by weight of triphenylbutylphosphonium bromide, which is a catalyst for addition reaction of hydroxyl group and epoxy group, was added and subjected to an addition polymerization reaction at 140 ° C. for 4 hours under a nitrogen flow to obtain a reaction product (Polymer A). )

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

  The reaction product (polymer A) obtained by GPC had a weight average molecular weight of 28,000 and a number average molecular weight of 8,000.

Thermosetting compound 1: Resorcinol type epoxy compound, “EX-201” manufactured by Nagase ChemteX Corporation
Thermosetting compound 2: Epoxy compound, “EXA-4850-150” manufactured by DIC, molecular weight 900, epoxy equivalent 450 g / eq

  Thermosetting agent 1: Trimethylolpropane tris (3-mercaptopropinate), “TMMP” manufactured by SC Organic Chemical Co., Ltd.

  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)

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

(Examples 1-4)
(1) Production of conductive paste The components shown in Table 1 below were blended in the blending amounts shown in Table 1 to obtain a conductive paste.

(2) Production of connection structure A glass epoxy substrate (thickness 0.8 mm, size 10 mm square, FR-4 substrate) on which no solder resist layer is formed on the surface, and a copper electrode (copper thickness 18 μm, A first connection target member having a size of 500 μm diameter and an electrode pitch of 1000 μm was formed in 3 rows × 5 rows. Vias are not formed immediately below the copper electrode and 1 mm in the periphery.

  The same second connection target member as the first connection target member was prepared.

  On the upper surface of the glass epoxy substrate, the conductive paste immediately after production was applied by screen printing using a metal mask so as to have a thickness of 100 μm on the electrode of the glass epoxy substrate, thereby forming a conductive paste layer. Next, the second connection target member was laminated on the upper surface of the conductive paste layer so that the electrodes face each other. At this time, no pressure was applied. The weight of the second connection target member is added to the conductive paste layer. Thereafter, while heating in a reflow oven so that the temperature of the anisotropic conductive paste layer becomes 190 ° C., the solder is melted and the conductive paste layer is cured at 190 ° C. for 5 minutes to obtain a first connection structure. It was.

(Example 5)
A connection structure 2 was produced in the same manner as in Example 1 except that the second connection target member was changed to a flexible printed board (thickness: 100 μm) having the same electrode pattern.

(Example 6)
A 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 conductive paste layer.

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

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

(Evaluation)
(1) Viscosity The viscosity η at 25 ° C. of the 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 between electrodes In the cross section (cross section in the direction shown in FIG. 1) of the obtained connection structure, the cured product is separated from the solder portion disposed between the electrodes in 100% of the total area of the solder. The area (%) of the solder remaining inside was evaluated. In addition, the average of the area in five cross sections was computed. The solder placement accuracy between the electrodes was determined according to the following criteria.

[Criteria for solder placement accuracy between electrodes]
○○: 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 ○: In 100% of the total area of the solder appearing in the cross section, the area of the solder (solder particles) remaining in the cured product away from the solder portion disposed between the electrodes exceeds 1% and is 10% or less Δ: Out of 100% of the total area of 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% and is 30% or less X: 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 30%

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

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

[Criteria for variation in conductivity]
○○: The difference between the maximum and minimum values of connection resistance is 5% or less of the average value of connection resistance ○: The difference between the maximum and minimum values of connection resistance exceeds 5% of the average value of connection resistance, and 10% △: The difference between the maximum and minimum values of connection resistance exceeds 10% of the average value of connection resistance, and 30% or less ×: The difference between the maximum and minimum values of connection resistance is 30% of the average value of connection resistance Exceed

(5) Insulation reliability between adjacent electrodes In the obtained connection structure (n = 15), after leaving in an atmosphere of 85 ° C. and 85% humidity for 100 hours, 5 V is applied between adjacent electrodes. The resistance value was measured at 25 locations. Insulation reliability was judged according to the following criteria.

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

  The results are shown in Table 1 below.

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

DESCRIPTION OF SYMBOLS 1,1X ... Connection structure 2 ... 1st connection object member 2a ... 1st conductor part 2b ... 1st via | veer 3,3X ... 2nd connection object member 3a, 3Xa ... 2nd conductor part 3b, 3Xb ... 2nd via | veer 4,4X ... 3rd connection object member 4a, 4Xa ... 3rd conductor part 4b, 4Xb ... 3rd via | veer 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 7 ... Via connection conductor part 11 ... 1st Conductive paste layer 11A ... solder particles 11B ... thermosetting component 12 ... second conductive paste layer 12A ... solder particles 12B ... thermosetting component

Claims (9)

A first conductive paste comprising a thermosetting component and a plurality of solder particles;
A first connection target member having a first conductor portion;
A second connection object member having a second conductor portion;
Using conductor material for connecting vias,
Applying the first conductive paste on one surface of the first connection target member and the second connection target member, and disposing a first conductive paste layer;
Disposing one of the second connection target member and the first connection target member on the surface of the first conductive paste layer;
By connecting the first connection target member and the second connection target member by heating the first conductive paste layer to a temperature equal to or higher than the melting point of the solder particles and equal to or higher than the curing temperature of the thermosetting component. The first connecting portion is formed by the first conductive paste layer, and the first conductor portion and the second conductor portion are electrically connected by the first solder portion derived from the solder particles. Connecting to each other,
A first via is formed in the first connection target member at a position different from a position where the first conductor part and the second conductor part are electrically connected by the first solder part. And the second via is formed in the second connection target member, or the first conductor portion is formed by the first solder portion after the step of forming the first connection portion. A first via is formed in the first connection target member at a position different from a position where the second conductor portion and the second conductor portion are electrically connected, and a second is formed in the second connection target member. Forming a via and forming an inter-via connection conductor portion connected to the first via and the second via with the inter-via connection conductor material.   In the step of arranging one of the second connection target member and the first connection target member and the step of forming the first connection portion, no pressure is applied and the first conductive paste layer is formed. The method for manufacturing a connection structure according to claim 1, wherein a weight of one of the second connection target member and the first connection target member is added.   The manufacturing method of the connection structure of Claim 1 or 2 whose average particle diameter of the said solder particle in a said 1st electrically conductive paste is 0.5 micrometer or more and 100 micrometers or less.   The manufacturing method of the connection structure of any one of Claims 1-3 whose content of the said solder particle in a said 1st electrically conductive paste is 10 to 80 weight%.   One of the second connection target member and the first connection target member disposed on the surface of the first conductive paste layer is a resin film, a flexible printed circuit board, a rigid flexible circuit board, or a flexible flat cable. The manufacturing method of the connection structure of any one of Claims 1-4 which exists. A second conductive paste comprising a thermosetting component and a plurality of conductive particles;
Using a third connection target member having a third conductor portion,
Applying the second conductive paste on a surface opposite to the second connection target member side of the first connection target member, and disposing a second conductive paste layer;
Disposing the third connection target member on the surface of the second conductive paste layer;
A second connection portion connecting the second connection target member and the third connection target member by heating the second conductive paste layer to a temperature equal to or higher than the curing temperature of the thermosetting component. And forming the second conductive paste layer and electrically connecting the first conductor portion and the third conductor portion by a conductive portion derived from the conductive particles. The manufacturing method of the connection structure of any one of Claims 1-5. The conductive particles contained in the second conductive paste are solder particles;
By heating the second conductive paste layer to a temperature equal to or higher than the melting point of the solder particles and equal to or higher than the curing temperature of the thermosetting component, the first connection target member and the third connection target member are connected. The second connection portion is formed by the second conductive paste layer, and the first conductor portion and the third conductor portion are formed by the second solder portion derived from the solder particles. Electrically connect,
The method for manufacturing a connection structure according to claim 6, wherein the conductor portion derived from the conductive particles is a second solder portion derived from the solder particles. Using conductor material for connecting vias,
A first via is formed in the first connection target member at a position different from a position where the first conductor portion and the third conductor portion are electrically connected by the second solder portion. And a third via is formed in the third connection target member, or the first conductor portion is formed by the second solder portion after the step of forming the second connection portion. A first via is formed in the first connection target member at a position different from a position where the third conductor portion is electrically connected to the third conductor portion, and a third connection is formed in the third connection target member. The connection structure according to claim 7, further comprising a step of forming a via and forming an inter-via connection conductor portion connected to the first via and the third via with the inter-via connection conductor material. Manufacturing method.   The connection structure obtained by the manufacturing method of the connection structure of any one of Claims 1-8.

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