JP2012174358A - Connection structure, and method for manufacturing connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure with low connection resistance between electrodes, and a high heat-resistant and shock-resistance characteristics.SOLUTION: A connection structure 1 according to the present invention comprises a first connection target member 2 having a first electrode 2b on an upper face 2a, a second connection target member 4 having a second electrode 4b on a lower face 4a, and a connection part 3 arranged between the upper face 2a of the first connection target member 2 and the lower face 4a of the second connection target member 4, and formed of an anisotropic conductive material including conductive particles 21. The conductive particle 21 has a resin particle 22, a first conductive layer 23, and a second conductive layer 24 with a melting point lower than that of the first conductive layer 23. The second conductive layer 24 of the conductive particle 21 is unevenly distributed asymmetrically upward and downward relative to a centerline passing through a center of the resin particle 22 of the conductive particle 21, and 70 volume % or more and 100 volume % or less of the entire second conductive layer 24 exists in an upper region or a lower region relative to the centerline.

Description

  The present invention relates to a connection structure using an anisotropic conductive material containing conductive particles. For example, the electrodes of various connection target members such as a flexible printed board, a glass substrate, and a semiconductor chip are electrically connected by conductive particles. The present invention relates to a connection structure connected to a wire, and a method for manufacturing the connection structure.

  Pasty or film-like anisotropic conductive materials are widely known. In the anisotropic conductive material, a plurality of conductive particles are dispersed in a binder resin or the like.

  The anisotropic conductive material is, for example, a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), or a semiconductor chip. It is used for connection with a glass substrate (COG (Chip on Glass)) and the like.

  For example, when the semiconductor chip electrode and the glass substrate electrode are electrically connected by the anisotropic conductive material, the anisotropic conductive material is disposed between the semiconductor chip electrode and the glass substrate electrode. Then, heat and pressurize. As a result, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

  As an example of the connection structure, a plurality of first electrodes provided on the first surface of the first electronic component is replaced with a plurality of second electrodes provided on the second surface of the second electronic component. A connection structure connected to is disclosed. The connection structure includes a resin portion that is interposed between the first surface and the second surface that are opposed to each other, and is surrounded by the resin portion. A substantially columnar solder portion connecting the second electrode corresponding thereto is provided. The solder portion has a constricted portion in which an outer peripheral surface is constricted on the inner side in at least two locations near the surface of the first electrode and in the vicinity of the surface of the second electrode, and the surface of the first electrode The contact angle with the surface of the second electrode is an acute angle.

JP 2007-149815 A

  In the conventional connection structure as described in Patent Document 1, the connection resistance between the electrodes connected by the solder portion may increase. Further, in the conventional connection structure, when a thermal shock such as a cooling / heating cycle is applied, the conduction reliability between the electrodes may be lowered. That is, a connection structure using a conventional anisotropic conductive material may have low thermal shock characteristics.

  An object of the present invention is to provide a connection structure capable of reducing the connection resistance between the electrodes and further improving the thermal shock resistance of the connection structure against a thermal shock such as a thermal cycle, and a method for manufacturing the connection structure. Is to provide.

According to a wide aspect of the present invention, a first connection target member having a first electrode on an upper surface, a second connection target member having a second electrode on a lower surface, and the upper surface of the first connection target member And a connecting portion formed of an anisotropic conductive material including conductive particles, the first and second electrodes being disposed between the second connection target member and the lower surface of the second connection target member. Electrically connected by conductive particles, the conductive particles being resin particles, a first conductive layer disposed on the surface of the resin particles, and a surface outside the first conductive layer; And a second conductive layer having a melting point lower than that of the first conductive layer, the first connection target member on the lower side, the second connection target member on the upper side, and the above In the state where the first and second connection target members are arranged such that the main surface is horizontal, the first and second electric power supplies are arranged. The second conductive layer is vertically asymmetrically distributed with respect to a center line passing through the center of the resin particles in the conductive particles electrically connected to each other, and is a region above the center line. Alternatively, a connection structure is provided in which 70% by volume or more and 100% by volume or less of the second conductive layer is present in a region below the center line.

  In a specific aspect of the connection structure according to the present invention, when the linear expansion coefficient of the first connection target member is larger than the linear expansion coefficient of the second connection target member, the center line is 70% by volume or more and 100% by volume or less of the second conductive layer exists in the lower region, and the linear expansion coefficient of the second connection target member is larger than the linear expansion coefficient of the first connection target member. When it is larger, 70% by volume or more and 100% by volume or less of the second conductive layer is present in the region above the center line.

  In another specific aspect of the connection structure according to the present invention, the first conductive layer in the conductive particles electrically connecting the first and second electrodes is connected to the first electrode. It is in contact with the second electrode.

  In another specific aspect of the connection structure according to the present invention, the melting point of the second conductive layer is lower by 50 ° C. or more than the melting point of the outermost layer of the first conductive layer.

  In still another specific aspect of the connection structure according to the present invention, the melting point of the second conductive layer is 100 ° C. or higher and 250 ° C. or lower, and the melting point of the outermost layer of the first conductive layer is 300 ° C. That's it.

  Moreover, according to the wide situation of this invention, the anisotropic conductive material layer using the anisotropic conductive material containing electroconductive particle is arrange | positioned on the 1st connection object member which has a 1st electrode on the upper surface. A step of laminating a second connection target member having a second electrode on the lower surface on the upper surface of the anisotropic conductive material layer, and forming a connecting portion by the anisotropic conductive material layer, A step of electrically connecting the first electrode and the second electrode by conductive particles, wherein the conductive particles are resin particles and a first particle disposed on the surface of the resin particles. Using conductive particles having a conductive layer and a second conductive layer disposed on the outer surface of the first conductive layer and having a melting point lower than that of the first conductive layer, the first The lower connection target member, the second connection target member on the upper side, and the first and second connection target members. The second conductive layer with respect to a center line passing through the center of the resin particles in the conductive particles electrically connecting the first and second electrodes in a state where the surfaces are arranged horizontally. So that the second conductive layer is 70% by volume or more and 100% by volume or less of the second conductive layer in the upper region with respect to the center line or the lower region with respect to the center line. Furthermore, a method for manufacturing a connection structure is provided in which the first electrode and the second electrode are electrically connected by the conductive particles.

In a specific aspect of the method for manufacturing a connection structure according to the present invention, when the linear expansion coefficient of the first connection target member is larger than the linear expansion coefficient of the second connection target member, the center line is used. The electrically conductive particles electrically connect the first electrode and the second electrode so that 70% by volume or more and 100% by volume or less of the second conductive layer exist in a lower region with respect to And when the linear expansion coefficient of the second connection target member is larger than the linear expansion coefficient of the first connection target member, the second conductive layer is formed in a region above the center line. The first electrode and the second electrode are electrically connected by the conductive particles such that 70 volume% or more and 100 volume% or less exist.

  In another specific aspect of the method for manufacturing a connection structure according to the present invention, the first conductive layer in the conductive particles that electrically connect the first and second electrodes is the first electrode. The first electrode and the second electrode are electrically connected by the conductive particles so as to be in contact with the second electrode.

  In another specific aspect of the method for manufacturing a connection structure according to the present invention, the conductive particles have a melting point of the second conductive layer of 50 ° C. or higher than the melting point of the outermost layer of the first conductive layer. Low conductive particles are used.

  In still another specific aspect of the method for manufacturing a connection structure according to the present invention, as the conductive particles, the second conductive layer has a melting point of 100 ° C. or higher and 250 ° C. or lower, and the first conductive layer. Conductive particles having a melting point of 300 ° C. or more of the outermost layer of the layer are used.

  In the connection structure according to the present invention, the first and second electrodes in the first and second connection target members are electrically connected by the conductive particles, and the conductive particles are resin particles, A first conductive layer disposed on the surface of the resin particles, and a second conductive layer disposed on the outer surface of the first conductive layer and having a melting point lower than that of the first conductive layer. And the second conductive layer is asymmetrically distributed vertically with respect to a center line passing through the center of the resin particles in the conductive particles electrically connecting the first and second electrodes. In the region above the center line or in the region below the center line, there is 70% by volume or more and 100% by volume or less of the entire second conductive layer. Connection resistance can be lowered. Furthermore, the thermal shock resistance characteristic of the connection structure against a thermal shock such as a cold cycle can be improved.

  In the method for manufacturing a connection structure according to the present invention, an anisotropic conductive material layer using an anisotropic conductive material containing conductive particles is disposed on a first connection target member having a first electrode on an upper surface. A step of laminating a second connection target member having a second electrode on the lower surface on the upper surface of the anisotropic conductive material layer, and forming a connection portion by the anisotropic conductive material layer, A step of electrically connecting the first electrode and the second electrode by the conductive particles, and the conductive particles electrically connecting the first and second electrodes. The second conductive layer is located in a region above the center line or in a region below the center line so that the second conductive layer is asymmetrically distributed vertically with respect to the center line passing through the center of the resin particles. The conductive layer is conductive so that 70% by volume or more and 100% by volume or less of the entire conductive layer is present. Because the sex particles electrically connecting the first electrode and the second electrode, it is possible to lower the connection resistance between the electrodes. Furthermore, the thermal shock resistance characteristic of the connection structure against a thermal shock such as a cold cycle can be improved.

FIG. 1 is a front sectional view schematically showing a connection structure according to an embodiment of the present invention. FIG. 2 is an enlarged front sectional view schematically showing a connection portion between the conductive particles and the first and second electrodes in the connection structure shown in FIG. FIGS. 3A to 3C are front sectional views schematically showing modifications of the connection structure between the conductive particles and the first and second electrodes. FIG. 4 is a cross-sectional view showing an example of conductive particles used to obtain a connection structure according to an embodiment of the present invention. FIG. 5 is a cross-sectional view showing a modification of the conductive particles. FIGS. 6A to 6B are front sectional views for explaining an example of each process for obtaining the connection structure according to the embodiment of the present invention. FIG. 7A is a cross-sectional view showing a connection structure between the conductive particles and the first and second electrodes in the connection structure obtained in Example 1, and FIG. It is sectional drawing which shows the connection structure of the electroconductive particle and the 1st, 2nd electrode in the connection structure obtained by (1). 8A is a cross-sectional view showing a connection structure between the conductive particles and the first and second electrodes in the connection structure obtained in Comparative Example 1, and FIG. FIG. 8C is a cross-sectional view showing a connection structure between the conductive particles and the first and second electrodes in the connection structure obtained in FIG. 8, and FIG. 8C shows the conductivity in the connection structure obtained in Comparative Example 3; It is sectional drawing which shows the connection structure of particle | grains and the 1st, 2nd electrode, FIG.8 (d) shows the electroconductive particle in the connection structure obtained in the comparative example 4, and the 1st, 2nd electrode. It is sectional drawing which shows these connection structures. FIG. 9 is an image obtained by enlarging a cross section of an example of the connection structure. FIG. 10 is an image obtained by enlarging a cross section of an example of the connection structure.

  Details of the present invention will be described below.

  A connection structure according to the present invention includes a first connection target member having a first electrode on an upper surface, a second connection target member having a second electrode on a lower surface, and an upper surface of the first connection target member. And a connecting portion formed of an anisotropic conductive material including conductive particles, which is disposed between the second connection target member and the lower surface of the second connection target member. The first and second electrodes are electrically connected by the conductive particles. The conductive particles are arranged on resin particles, a first conductive layer disposed on the surface of the resin particles, an outer surface of the first conductive layer, and the first conductive layer. And a second conductive layer having a lower melting point. The first connection target member having the first electrode on the upper surface is the lower side, the second connection target member having the second electrode on the lower surface is the upper side, and the first and second connection target members are In a state in which the main surface is arranged horizontally, the first and second electrodes are electrically connected to the conductive particles, and the conductive particles are connected to the center line passing through the center of the resin particles. The two conductive layers are asymmetrically distributed in the vertical direction, and are 70% by volume or more and 100% by volume of the entire second conductive layer in a region above the center line or a region below the center line. The following exist: That is, 70% by volume or more and 100% by volume or less of the entire second conductive layer exists in a region on one side in the vertical direction with respect to the center line. The entire second conductive layer may be present in the upper region or may be present in the lower region.

  From the viewpoint of further improving the thermal shock resistance of the connection structure, when the linear expansion coefficient of the first connection target member is larger than the linear expansion coefficient of the second connection target member, It is preferable that 70% by volume or more and 100% by volume or less of the second conductive layer is present in the lower region. When the linear expansion coefficient of the second connection target member is larger than the linear expansion coefficient of the first connection target member, 70% by volume of the second conductive layer in the region above the center line. As mentioned above, it is preferable that 100 volume% or less exists. For example, when connecting a semiconductor chip and a glass epoxy substrate, the linear expansion coefficient of the glass epoxy substrate is larger than the linear expansion coefficient of the semiconductor chip. Tends to occur. On the other hand, the thermal shock characteristics of the connection structure can be further enhanced by providing a large amount of the second conductive layer on the side where the linear expansion coefficient is large.

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

  In FIG. 1, the connection structure which concerns on one Embodiment of this invention is typically shown with front sectional drawing.

A connection structure 1 shown in FIG. 1 includes a first connection target member 2, a second connection target member 4, and a first connection target member 2.
, And a connection portion 3 disposed between the second connection target members 2 and 4. The connection unit 3 connects the first and second connection target members 2 and 4. The connection part 3 is formed of an anisotropic conductive material including a plurality of conductive particles 21.

  The first connection target member 2 has a plurality of first electrodes 2b on the upper surface 2a. The second connection target member 4 has a plurality of second electrodes 4b on the lower surface 4a. The first electrode 2 b and the second electrode 4 b are electrically connected by one or a plurality of conductive particles 21. The conductive particles 21 electrically connecting the first and second electrodes 2b and 4b in the connection structure 1 are conductive particles after the first and second electrodes 2b and 4b are connected. In addition, like the connection structure 1, the connection part 3 may include the conductive particles 21 that are not electrically connected to the first and second electrodes 2b and 4b.

  In order to obtain the connection structure 1, the electroconductive particle 21 shown in FIG. 4 is used. The conductive particles 21 shown in FIG. 4 are conductive particles before connection of the first and second electrodes 2b and 4b.

  The conductive particles 21 shown in FIG. 4 include resin particles 22, a first conductive layer 23, and a second conductive layer 24. The melting point of the second conductive layer 24 is lower than the melting point of the first conductive layer 23.

  The first conductive layer 23 is disposed on the surface 22 a of the resin particle 22. In the conductive particle 21, the first conductive layer 23 is directly laminated on the surface 22 a of the resin particle 22. The first conductive layer 23 covers the surface 22 a of the resin particle 22. The first conductive layer 23 has a single layer structure. The entire first conductive layer 23 is the outermost layer of the first conductive layer. The first conductive layer 23 is an inner layer.

  The second conductive layer 24 is disposed on the outer surface 23 a of the first conductive layer 23. The second conductive layer 24 is directly laminated on the outer surface 23 a of the first conductive layer 23. The second conductive layer 24 covers the outer surface 23 a of the first conductive layer 23. The second conductive layer 24 has a one-layer structure. The second conductive layer 24 is an outer layer.

  FIG. 2 is a front cross-sectional view schematically showing an enlarged connection portion between the conductive particles 21 and the first and second electrodes 2b and 4b in the connection structure 1 shown in FIG. 1-2, the first connection target member 2 having the first electrode 2b on the upper surface 2a is on the lower side, the second connection target member 4 having the second electrode 4b on the lower surface 4a is on the upper side, and the first The state which has arrange | positioned the 2nd connection object members 2 and 4 so that the main surface is horizontal is shown.

  In the connection structure 1, as shown in FIG. 2, the second conductive layer 24 in the conductive particles 21 is melted and solidified after wetting and spreading on the surface of the second electrode 4b. That is, the second conductive layer 24 extends laterally from the contact point between the first conductive layer 23 and the second electrode 4b. For this reason, the contact area between the second conductive layer 24 and the second electrode 4b is considerably large. For this reason, in the connection structure 1, peeling with the electroconductive particle 21 and the 2nd electrode 4b becomes difficult to produce, and the conduction | electrical_connection reliability between the 1st, 2nd electrodes 2b and 4b can be improved. Furthermore, since the contact area between the second conductive layer 24 and the second electrode 4b is large, it is possible to improve the thermal shock resistance of the connection structure against a thermal shock such as a thermal cycle.

On the other hand, the second conductive layer 24 does not wet and spread on the surface of the first electrode 2b, and the second conductive layer 24 located on the first electrode 2b side is on the second electrode 4b side. Has moved. In the state shown in FIGS. 1 and 2, the second conductive layer 24 is vertically asymmetric with respect to the center line (broken line and dashed line in FIG. 2) passing through the center of the resin particle 22 in the conductive particle 21. It is unevenly distributed left and right. The second conductive layer 24 has a laterally asymmetric region and a vertically asymmetric region with respect to a center line passing through the center of the resin particle 22 in the conductive particle 21. That is, the second conductive layer 24 is unevenly distributed in the vertical direction with respect to the center line (broken line). Further, the abundance of the second conductive layer 24 differs between the upper region and the lower region with respect to the center line. 70% by volume or more and 100% by volume or less of the second conductive layer 24 exists in a region above the center line. The second conductive layer 24 is asymmetrically distributed with respect to the center line (dashed line). The abundance of the second conductive layer 24 differs between the one side region and the other side region in the left-right direction with respect to the center line, and the second conductive layer 24 exists between the left region and the right region. The amount is different. Note that the second conductive layer may exist symmetrically with respect to the center line.

  As shown in FIG. 2, after the connection between the first and second electrodes 2b and 4b, the first conductive layer 23 in the conductive particles 21 is in contact with the first electrode 2b and the second electrode 4b. ing. Here, the first conductive layer 23 is in physical contact with the first electrode 2b and the second electrode 4b. For this reason, the initial resistance between the first and second electrodes 2b and 4b is further reduced, and the conduction reliability is further enhanced. Furthermore, the thermal shock resistance of the connection structure against a thermal shock such as a thermal cycle is further enhanced.

  The first conductive layer may be in contact with the first and second electrodes while being alloyed with the second conductive layer or the first and second electrodes. For example, when the first conductive layer is a copper layer and the second conductive layer is a layer containing tin, the first and first conductive layers are in an alloy layer in which copper is alloyed with tin. It may be in contact with the two electrodes. In the contact between the first conductive layer and the first and second electrodes in the present invention, the first conductive layer is alloyed with the second conductive layer or the first and second electrodes. The case where it is in contact with the first and second electrodes in the state is also included.

  As shown in FIG. 2, in the connection structure 1, the resin particles 22 having the first conductive layer 23 are compressed and flattened so as not to be spherical. Thus, the resin particles 22 having the first conductive layer 23 may be compressed and deformed. In this case, the contact area between the first conductive layer 23 and the first and second electrodes 2b and 4b increases. For this reason, the initial resistance between the first and second electrodes 2b and 4b is further reduced, and the conduction reliability is further enhanced.

  3A to 3C schematically show a modification of the connection structure between the conductive particles and the first and second electrodes. 3A to 3C, similarly to FIGS. 1 and 2, the first connection target member 2 having the first electrode 2b on the upper surface 2a is provided on the lower side, and the second electrode 4b is provided on the lower surface 4a. The state which has arrange | positioned the 2nd connection object member 4 so that the main surface may be horizontal, and the 1st, 2nd connection object members 2 and 4 is shown.

  In FIG. 3A, the second conductive layer 24A of the conductive particles 21A is melted and solidified after wetting and spreading on the surface of the first electrode 2b. On the other hand, the second conductive layer 24A does not wet and spread on the surface of the second electrode 4b, and the second conductive layer 24A located on the second electrode 4b side is on the first electrode 2b side. Has moved. Further, in the state shown in FIG. 3A, the second conductive layer 24A has a laterally asymmetric region with respect to the center line passing through the center of the resin particle 22 in the conductive particle 21A and is vertically asymmetric. Has a region. That is, the second conductive layer 24A is unevenly distributed asymmetrically with respect to the center line. The abundance of the second conductive layer 24A differs between the upper region and the lower region with respect to the center line. 70% by volume or more and 100% by volume or less of the second conductive layer 24A exists in a region below the center line. The second conductive layer 24A is unevenly distributed with respect to the center line. The abundance of the second conductive layer 24A differs between the one side region and the other side region with respect to the center line, and the second conductive layer 24A exists between the left region and the right region. The amount is different.

In FIG. 3B, the second conductive layer 24B in the conductive particles 21B is melted and solidified after wetting and spreading on the surface of the first electrode 2b. On the other hand, the second conductive layer 24B does not wet and spread on the surface of the second electrode 4b, and the second conductive layer 24B located on the second electrode 4b side is on the first electrode 2b side. Has moved. In the state shown in FIG. 3B, the second conductive layer 24B has a bilaterally symmetric and vertically asymmetric region with respect to the center line passing through the center of the resin particle 22 in the conductive particle 21B. . That is, the second conductive layer 24B is unevenly distributed in the vertical direction with respect to the center line. In addition, the abundance of the second conductive layer 24B differs between the upper region and the lower region with respect to the center line. 70% by volume or more and 100% by volume or less of the second conductive layer 24B exists in a region below the center line. The abundance of the second conductive layer 24B is substantially the same in the region on the one side and the region on the other side in the left-right direction with respect to the center line.

  In FIG. 3C, the second conductive layer 24C in the conductive particles 21C is melted and solidified after wetting and spreading on the surface of the second electrode 4b. On the other hand, the second conductive layer 24C does not wet and spread on the surface of the first electrode 2b, and the second conductive layer 24C located on the first electrode 2b side is on the second electrode 4b side. Has moved. Further, in the state shown in FIG. 3C, the second conductive layer 24C is symmetrical with respect to the center line passing through the center of the resin particle 22 in the conductive particle 21C and has a vertically asymmetric region. . That is, the second conductive layer 24C is unevenly distributed in the up-down direction with respect to the center line. The abundance of the second conductive layer 24C differs between the upper region and the lower region with respect to the center line. 70% by volume or more and 100% by volume or less of the second conductive layer 24C exists in the region above the center line. With respect to the center line, the abundance of the second conductive layer 24 </ b> C is substantially the same in one region in the left-right direction and the other region.

  9 and 10 show images taken by enlarging a cross section of an example of the connection structure.

(Details of conductive particles)
In the connection structure 1 shown in FIG. 1, the conductive particles 21 shown in FIG. 4 are used.

  FIG. 5 is a sectional view showing a modification example of the conductive particles. The conductive particles 31 illustrated in FIG. 5 include resin particles 22, a first conductive layer 32, and a second conductive layer 33. The melting point of the second conductive layer 33 is lower than that of the first conductive layer 32. The conductive particles 21 and the conductive particles 31 differ only in the conductive layer.

  The first conductive layer 32 is disposed on the surface 22 a of the resin particle 22. The first conductive layer 32 covers the surface 22 a of the resin particle 22. The first conductive layer 32 has a multilayer structure of two layers and is a multilayer. The first conductive layer 32 includes an inner first conductive layer 32A and an outer first conductive layer 32B. The inner first conductive layer 32 </ b> A is not the outermost layer of the first conductive layer 32. The outer first conductive layer 32 </ b> B is the outermost layer of the first conductive layer 32. The first conductive layer 32 is an inner layer.

  The second conductive layer 33 is disposed on the outer surface 32 a of the first conductive layer 32. The second conductive layer 33 is directly laminated on the outer surface 32 a of the first conductive layer 32. The second conductive layer 33 is disposed on the surface of the outer first conductive layer 32 </ b> B that is the outermost layer of the first conductive layer 32. The second conductive layer 33 covers the outer surface 32a of the first conductive layer 32 and the outer surface of the outer first conductive layer 32B. The second conductive layer 33 has a single layer structure. The second conductive layer 33 is an outer layer.

  Like the conductive particles 21 and 31, the first conductive layer may have a single-layer structure or a two-layer stacked structure. Furthermore, the first conductive layer may have a stacked structure of two or more layers.

  The resin particles are made of resin. When connecting the electrodes, the conductive particles are generally compressed after the conductive particles are arranged between the electrodes. When the core particles are resin particles, the conductive particles are easily deformed by compression, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes can be improved. Furthermore, the flexibility of the conductive particles can be increased when the resin particles are not particles formed of metal such as nickel or glass but resin particles formed of resin. When the flexibility of the conductive particles is high, damage to the electrode in contact with the conductive particles can be suppressed.

  Examples of the resin for forming the resin particles include polyolefin resin, acrylic resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, and polyphenylene. Examples thereof include oxides, polyacetals, polyimides, polyamideimides, polyetheretherketones, and polyethersulfones. Since the conductive particles can be appropriately deformed by compression, the resin particles are formed of a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. Is preferred. The fact that the core particles are resin particles greatly contributes to reducing the connection resistance between the electrodes in the connection structure and improving the thermal shock resistance.

  The first and second conductive layers are preferably made of metal. The metal which comprises the 1st, 2nd conductive layer is not specifically limited. Examples of the metal include tin, gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and alloys thereof. It is done. In addition, tin-doped indium oxide (ITO) can also be used as the metal. As for the said metal, only 1 type may be used and 2 or more types may be used together.

  The method for forming the first conductive layer on the surface of the resin particles and the method for forming the second conductive layer on the surface of the first conductive layer are not particularly limited. As a method of forming the first and second conductive layers, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by physical vapor deposition, and metal powder or metal powder and binder And a method of coating the surface of the resin particles with a paste containing Of these, electroless plating or electroplating is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method based on the physical collision, for example, a theta composer or the like is used.

  From the viewpoint of further reducing the connection resistance between the electrodes, the outermost layer of the first conductive layer is preferably a nickel layer, a copper layer, or a silver layer, and more preferably a copper layer.

  From the viewpoint of further reducing the connection resistance between the electrodes, the conductivity of the outermost layer of the first conductive layer is preferably higher than the conductivity of the second conductive layer.

From the viewpoint of further facilitating connection between the electrodes and further improving the conduction reliability in the connection structure, the melting point of the second conductive layer is preferably less than 300 ° C. That is, the second conductive layer is preferably a low melting point conductive layer having a melting point of less than 300 ° C. From the viewpoint of further facilitating the connection between the electrodes and further enhancing the conduction reliability in the connection structure, the melting point of the second conductive layer is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. Preferably it is 280 degrees C or less, More preferably, it is 250 degrees C or less, Most preferably, it is 220 degrees C or less. The melting point of the second conductive layer is particularly preferably 100 ° C. or higher and 250 ° C. or lower. From the viewpoint of facilitating the connection between the electrodes and further improving the conduction reliability in the connection structure, the melting point of the second conductive layer is 5 5 higher than the melting point of the outermost layer of the first conductive layer. Is preferably lower by 10 ° C. or more, more preferably by 10 ° C. or more, and 20
More preferably, the temperature is lower by at least 40 ° C, particularly preferably by at least 40 ° C, and most preferably by at least 50 ° C. The melting point of the first conductive layer is preferably 300 ° C. or higher. The upper limit of the melting point of the first conductive layer is not particularly limited, and is appropriately determined depending on the metal used.

  Before the connection of the first and second electrodes, the second conductive layer is preferably disposed on the entire surface of the first conductive layer. The second conductive layer is preferably laminated directly on the entire surface of the first conductive layer. The second conductive layer preferably covers the entire surface of the first conductive layer. In these cases, the second conductive layer is not partially disposed or laminated on the surface of the first conductive layer and does not partially cover the surface of the first conductive layer. . When the second conductive layer is disposed or laminated on the entire surface of the first conductive layer, the oxidation of the first conductive layer does not easily progress partially. For this reason, the conduction | electrical_connection reliability of a connection structure can fully be improved.

  From the viewpoint of further facilitating the connection between the electrodes and further enhancing the conduction reliability in the connection structure, the second conductive layer is preferably a layer containing tin, and preferably a solder layer. Particularly preferred. The tin-containing layer and the solder layer may be alloy layers. In such conductive particles having the second conductive layer, the second conductive layer can be melted more easily by heating, and the contact area between the second conductive layer and the electrode can be increased. . Therefore, when the second conductive layer is a low melting point metal layer, a layer containing tin, or a solder layer, the outer surface layer of the conductive layer is a gold layer or a nickel layer. Compared with conductive particles that are metals other than the solder layer, conduction reliability can be improved.

From the viewpoint of further reducing the connection resistance between the electrodes and further improving the thermal shock resistance of the connection structure, the conductive particles were compressed by 20% before the connection of the first and second electrodes. The compressive elastic modulus (20% K value) is preferably 1000 N / mm ² or more, preferably 8000 N / mm ² or less.

Further more reduce the connection resistance between the electrodes, and further from the viewpoint of further enhancing the thermal shock resistance of the connection structure, 20% K value is more preferably 1200 N / mm ² or more, more preferably 1500 N / mm ² or more, more preferably 7000N / mm ^2, more preferably not more than 6000 N / mm ^2. Further, when the 20% K value is not less than the above lower limit, the conductive particles are hardly destroyed when compressed.

  The compression elastic modulus (20% K value) can be measured as follows.

  Using a micro-compression tester, the conductive particles are compressed under the conditions of a compression rate of 2.6 mN / sec and a maximum test load of 10 g with the end face of a diamond cylinder having a diameter of 50 μm. The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus can be obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value when the conductive particles are 20% compressively deformed (N)
S: Compression displacement (mm) when conductive particles are 20% compressively deformed
R: radius of conductive particles (mm)

  The compression elastic modulus universally and quantitatively represents the hardness of the conductive particles. By using the compression elastic modulus, the hardness of the conductive particles can be expressed quantitatively and uniquely.

From the viewpoint of further reducing the connection resistance between the electrodes and further improving the thermal shock resistance of the connection structure, the compression recovery rate of the conductive particles is preferably before the connection of the first and second electrodes. Is 20% or more, preferably 90% or less.

  From the viewpoint of further reducing the connection resistance between the electrodes and further improving the thermal shock resistance of the connection structure, the compression recovery rate is more preferably 25% or more, further preferably 30% or more, more preferably 85. % Or less, more preferably 80% or less. Further, when the compression recovery rate is less than or equal to the above upper limit, the repulsive force of the conductive particles used for the connection between the electrodes is further reduced, and the anisotropic conductive material is difficult to peel from the substrate or the like. As a result, it is possible to further suppress an increase in the connection resistance between the electrodes.

  The compression recovery rate can be measured as follows.

  Spread conductive particles on the sample stage. With respect to one dispersed conductive particle, a load is applied to the inversion load value (5.00 mN) in the central direction of the conductive particle using a micro compression tester. Thereafter, the load is gradually reduced to the load value for origin (0.40 mN). The load-compression displacement during this period is measured, and the compression recovery rate can be obtained from the following equation. The load speed is 0.33 mN / sec. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

Compression recovery rate (%) = [(L1-L2) / L1] × 100
L1: Compressive displacement from the load value for the origin to the reverse load value when applying the load L2: Compressive displacement from the reverse load value to the load value for the origin when releasing the load

(Details of anisotropic conductive material)
The anisotropic conductive material preferably contains the above-described conductive particles and a binder resin.

  The binder resin is not particularly limited. As the binder resin, for example, an insulating resin is used. Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. As for the said binder resin, only 1 type may be used and 2 or more types may be used together.

  Specific examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Specific examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer and polyamide resin. Specific examples of the curable resin include epoxy resins, urethane resins, polyimide resins and unsaturated polyester resins. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. Specific examples of the thermoplastic block copolymer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and styrene- Examples include hydrogenated products of isoprene-styrene block copolymers. Specific examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

  The binder resin is preferably a thermosetting compound. In this case, by heating at the time of electrically connecting the electrodes, the second conductive layer such as a solder layer of conductive particles can be melted and the binder resin can be cured. For this reason, the connection between electrodes and the connection of the connection object member by binder resin can be performed simultaneously.

From the viewpoint of further improving the thermal shock resistance of the connection structure, the thermosetting compound is preferably an epoxy compound.

  The anisotropic conductive material preferably contains a curing agent in order to cure the binder resin.

  The said hardening | curing agent is not specifically limited. Examples of the curing agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, and acid anhydride curing agents. As for a hardening | curing agent, only 1 type may be used and 2 or more types may be used together.

  The anisotropic conductive material preferably further includes a flux. By using the flux, it becomes difficult to form an oxide film on the surface of the second conductive layer such as a solder layer, and the oxide film formed on the second conductive layer or the electrode surface can be effectively removed.

  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. Is mentioned. Only 1 type of flux 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 hydrazine. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux is preferably rosin. By using pine resin, the connection resistance between the electrodes can be lowered.

  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 connection resistance between the electrodes can be further reduced.

  The said flux may be disperse | distributed in binder resin and may adhere on the surface of electroconductive particle.

  The anisotropic conductive material may contain a basic organic compound in order to adjust the activity of the flux. Examples of the basic organic compound include aniline hydrochloride and hydrazine hydrochloride.

  From the viewpoint of achieving both conductivity and insulation in the connection structure, the content of the binder resin is preferably 30% by weight or more, more preferably 50% by weight or more, in 100% by weight of the anisotropic conductive material. More preferably, it is 80 weight% or more, Preferably it is 99.99 weight% or less, More preferably, it is 99.9 weight% or less. When the content of the binder resin is not less than the above lower limit and not more than the above upper limit, a short circuit between adjacent electrodes can be further prevented, and the connection reliability of a connection target member connected by an anisotropic conductive material can be improved. It can be further increased.

  When a curing agent is used, the content of the curing agent is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, preferably 100 parts by weight or less with respect to 100 parts by weight of the binder resin. More preferably, it is 50 parts by weight or less. When the content of the curing agent is not less than the above lower limit and not more than the above upper limit, the binder resin can be sufficiently cured, and a residue derived from the curing agent is less likely to occur after curing.

In 100% by weight of the anisotropic conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 20% by weight or less, more preferably 10% by weight. % Or less. When the content of the conductive particles is not less than the above lower limit and not more than the above upper limit, short-circuiting between adjacent electrodes can be further prevented, and conduction reliability between the electrodes can be further enhanced.

  In 100 wt% of the anisotropic conductive material, the flux content is 0 wt% or more, preferably 0.5 wt% or more, preferably 30 wt% or less, more preferably 25 wt% or less. The anisotropic conductive material may not contain a flux. When the flux content is not less than the above lower limit and not more than the above upper limit, an oxide film is more difficult to be formed on the surface of the solder layer, and the oxide film formed on the solder layer or the electrode surface is more effective. Can be removed.

  The anisotropic conductive material includes, 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, a lubricant, and a charge. Various additives such as an inhibitor or a flame retardant may be further included.

  The method for dispersing the conductive particles in the binder resin is not particularly limited, and a conventionally known dispersion method can be used. Examples of the method for dispersing the conductive particles in the binder resin include, for example, a method in which the conductive particles are added to the binder resin and then kneaded and dispersed with a planetary mixer or the like. The conductive particles are dispersed in water or an organic solvent. After uniformly dispersing using a homogenizer, etc., adding into a binder resin, kneading and dispersing with a planetary mixer, etc., and after diluting the binder resin with water or an organic solvent, the conductive particles are The method of adding, kneading | mixing with a planetary mixer etc., and dispersing is mentioned.

  The anisotropic conductive material can be used as an anisotropic conductive paste or an anisotropic conductive film. When the anisotropic conductive material containing the conductive particles of the present invention is used as a film-like adhesive such as an anisotropic conductive film or an anisotropic conductive sheet, the film-like shape containing the conductive particles is used. A film-like adhesive that does not contain conductive particles may be laminated on the adhesive. However, the anisotropic conductive material is preferably in a liquid state, and is preferably an anisotropic conductive paste.

(Method for manufacturing connection structure)
In the method for manufacturing a connection structure according to the present invention, an anisotropic conductive material layer using an anisotropic conductive material containing conductive particles is disposed on a first connection target member having a first electrode on an upper surface. A step of laminating a second connection object member having a second electrode on the lower surface on the upper surface of the anisotropic conductive material layer, and forming a connection portion by the anisotropic conductive material layer, Electrically connecting the first electrode and the second electrode with the conductive particles. In the method for manufacturing a connection structure according to the present invention, as the conductive particles, resin particles, a first conductive layer disposed on the surface of the resin particles, and an outer surface of the first conductive layer And conductive particles having a second conductive layer which is disposed in the first conductive layer and has a melting point lower than that of the first conductive layer. Moreover, in the manufacturing method of the connection structure according to the present invention, the second connection target member having the first connection target member having the first electrode on the upper surface and the second electrode on the lower surface. And the resin particles in the conductive particles that electrically connect the first and second electrodes in a state where the first and second connection target members are arranged so that the main surface is horizontal. The second conductive layer is located in an upper region with respect to the center line or in a lower region with respect to the center line so that the second conductive layer is unevenly distributed in the vertical direction with respect to a center line passing through the center of the center line. The first electrode and the second electrode are electrically connected by the conductive particles so that 70% by volume to 100% by volume of the conductive layer exists.

From the viewpoint of further improving the thermal shock resistance of the connection structure, when the linear expansion coefficient of the first connection target member is larger than the linear expansion coefficient of the second connection target member, The first electrode and the second electrode are electrically connected by the conductive particles so that 70% by volume or more and 100% by volume or less of the second conductive layer exists in the lower region. It is preferable to do. When the linear expansion coefficient of the second connection target member is larger than the linear expansion coefficient of the first connection target member, 70% by volume of the second conductive layer in the region above the center line. As described above, it is preferable that the first electrode and the second electrode are electrically connected by the conductive particles so that 100% by volume or less exists.

  Specifically, the connection structure 1 shown in FIG. 1 can be obtained as follows, for example, through the states shown in FIGS.

  As shown to Fig.6 (a), the 1st connection object member 2 which has the 1st electrode 2b in the upper surface 2a is prepared. In addition, an anisotropic conductive material including a plurality of conductive particles 21 is prepared. Next, the anisotropic conductive material layer 3 </ b> A is disposed on the upper surface 2 a of the first connection target member 2 using an anisotropic conductive material including a plurality of conductive particles 21. At this time, it is preferable that one or a plurality of conductive particles 21 be disposed on the first electrode 2b. Here, since the anisotropic conductive paste is used as the anisotropic conductive material, the anisotropic conductive paste is arranged by applying the anisotropic conductive paste. In addition, in FIG. 6 (a), (b), the electroconductive particle 21 is shown schematically.

  Next, as shown in FIG. 6B, the second connection target member 4 having the second electrode 4b on the lower surface 4a is laminated on the upper surface 3a of the anisotropic conductive material layer 3A. The second connection target member 4 is laminated so that the first electrode 2b and the second electrode 4b face each other. In the state shown in FIG. 6B, the second conductive layer 24 in the conductive particles 21 is not yet melted. When the second connection target member 4 is laminated, the anisotropic conductive material layer 3 </ b> A is cured by applying (heating) the anisotropic conductive material layer 3 </ b> A to form the connection portion 3. At this time, the upper surface of the second connection target member 4 is heated and pressurized, and the anisotropic conductive material layer 3A is cured by applying heat to the anisotropic conductive material layer 3A to form the connection portion 3. It is preferable to do. The contact area between the first and second electrodes 2b and 4b and the conductive particles 21 can be increased by compressing the conductive particles 21 with the first electrode 2b and the second electrode 4b by pressurization. it can. For this reason, conduction reliability can be improved. However, heat may be applied to the anisotropic conductive material layer 3 </ b> A before the second connection target member 4 is laminated. Furthermore, heat may be applied to the anisotropic conductive material layer 3 </ b> A after the second connection target member 4 is laminated.

  The heating temperature for curing the anisotropic conductive material layer 3A is preferably 160 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 ° C. or lower.

  By curing the anisotropic conductive material layer 3 </ b> A, the first connection target member 2 and the second connection target member 4 are connected by the connection portion 3. Further, the second conductive layer 24 is unevenly distributed in a vertically asymmetrical manner so that the upper conductive layer 24 is 70% by volume or more of the second conductive layer 24 in the upper region with respect to the center line or the lower region with respect to the center line. The 1st electrode 2b and the 2nd electrode 4b are electrically connected by the electroconductive particle 21 so that 100 volume% or less exists. As a result, the first electrode 2 b and the second electrode 4 b are electrically connected by the conductive particles 21. In this way, the connection structure 1 shown in FIG. 1 can be obtained.

  The anisotropic conductive material layer 3A may be cured stepwise. For example, the anisotropic conductive material layer 3A is irradiated with light using an anisotropic conductive material having thermosetting property and photo-curing property, and the anisotropic conductive material layer 3A is cured to be B stage. After forming a B-staged anisotropic conductive material layer on the upper surface 2a of the first connection target member 2, the B-staged anisotropic conductive material layer is cured by applying heat. Thus, a connection portion may be formed.

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.

Example 1
(1) Production of conductive particles Polymer resin particles having an average particle diameter of 3 μm were subjected to electroless nickel plating, and a base nickel plating layer (plating thickness: 0.1 μm) was formed on the surface of the resin particles. Next, the resin particles on which the base nickel plating layer was formed were subjected to electrolytic copper plating to form a copper layer (plating thickness: 0.3 μm). Thereafter, using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), on the surface of the copper layer of the obtained particles, an average particle diameter of 0.1 μm containing fine solder powder (42% by weight of tin and 58% by weight of bismuth) ) Was melted to form a 0.5 μm thick solder layer on the surface of the copper layer.

  Thus, the conductive particle A in which the copper layer is formed on the surface of the resin particle, and the solder layer (tin: bismuth = 42 wt%: 58 wt%) is formed on the surface of the copper layer. Was made. The melting point of the copper layer was 1084 ° C. The melting point of the solder layer (containing 42% by weight of tin) was 138 ° C.

(2) Production of anisotropic conductive paste 90 parts by weight of Epicoat 828 (manufactured by Mitsubishi Chemical) which is an epoxy resin and 10 parts by weight of Epicoat 1001 (manufactured by Mitsubishi Chemical) and PN-23J which is an amine adduct curing agent ( After mixing 10 parts by weight of Ajinomoto Fine-Techno Co., Ltd. and 10 parts by weight of the resulting conductive particles A, the anisotropically conductive paste is stirred by stirring at 2000 rpm for 5 minutes using a planetary stirrer. Conductive material was obtained.

  An FR-4 substrate (first connection target member) having a gold electrode (first electrode) disposed on the upper surface was prepared. In addition, a semiconductor chip (second connection target member) having a gold electrode (second electrode) disposed on the lower surface was prepared. The area of the contact portion is 90000 im. Note that the linear expansion coefficient of the FR-4 substrate is larger than the linear expansion coefficient of the semiconductor chip.

  An anisotropic conductive material layer was formed on the upper surface of the FR-4 substrate so as to have a thickness of 10 μm using the obtained anisotropic conductive material. Next, a semiconductor chip was stacked on the upper surface of the anisotropic conductive material layer so that the electrodes face each other. Then, the anisotropic conductive material layer is cured while adjusting the temperature of the head so that the temperature of the anisotropic conductive material layer becomes 200 ° C. and placing a pressure heating head on the upper surface of the semiconductor chip and applying pressure. Thus, a connection structure was obtained.

  In the obtained connection structure, the solder layer was melted and solidified after wetting and spreading on the surface of the second electrode. In the obtained connection structure, the copper layer was in contact with the second electrode, and the conductive particles A were in the state shown in FIG. With respect to the center line passing through the center of the resin particle in the conductive particle A, the solder layer is unevenly distributed in the vertical direction, and 75% by volume of the solder layer is present in the region below the center line ( (A part of the solder layer exists in the upper region not shown). Moreover, the solder layer was unevenly distributed with respect to the center line.

(Example 2)
Conductive particles B were prepared in the same manner as in Example 1 except that the thickness of the solder layer was changed from 0.5 μm to 0.7 μm when the conductive particles were prepared. An anisotropic conductive paste and a connection structure were produced in the same manner as in Example 1 except that the conductive particles A were changed to the obtained conductive particles B.

In the obtained connection structure, the solder layer was melted and solidified after wetting and spreading on the surface of the first electrode. In the obtained connection structure, the copper layer was in contact with the first electrode, and the conductive particles B were in the state shown in FIG. With respect to the center line passing through the center of the resin particle in the conductive particle B, the solder layer is unevenly distributed in the vertical direction, and 85% by volume of the solder layer is present in the region below the center line ( A part of the solder layer is also present in the upper region (not shown)). Moreover, the solder layer was unevenly distributed with respect to the center line.

(Comparative Example 1)
Conductive particles C were prepared in the same manner as in Example 1 except that the thickness of the solder layer was changed from 0.5 μm to 0.2 μm when the conductive particles were manufactured. An anisotropic conductive paste and a connection structure were produced in the same manner as in Example 1 except that the conductive particles A were changed to the obtained conductive particles C.

  In the obtained connection structure, the solder layer was melted and solidified after wetting and spreading on the surfaces of the first and second electrodes. In the obtained connection structure, the copper layer was in contact with the first electrode, and the conductive particles C were in the state shown in FIG. With respect to the center line passing through the center of the resin particles in the conductive particles C, the solder layers existed vertically and symmetrically.

(Comparative Example 2)
Solder particles X (tin: bismuth = 43 wt%: 57 wt%, average particle size 5 μm) were prepared. An anisotropic conductive paste and a connection structure were produced in the same manner as in Example 1 except that the conductive particles A were changed to the solder particles X.

  In the obtained connection structure, the solder particles X were melted and melted and solidified after wetting and spreading on the surfaces of the first and second electrodes. In the obtained connection structure, the solder particles X are in contact with the first and second electrodes, and the solder particles X are in the state shown in FIG.

(Comparative Example 3)
(1) Production of conductive particles Polymer resin particles having an average particle diameter of 3 μm were subjected to electroless nickel plating, and a base nickel plating layer (plating thickness: 0.1 μm) was formed on the surface of the resin particles. Next, the resin particles on which the base nickel plating layer was formed were subjected to electrolytic copper plating to form a copper layer (plating thickness: 0.3 μm). Thus, the electroconductive particle D in which the copper layer was formed on the surface of the resin particle was produced.

(2) Production of anisotropic conductive paste and connection structure A connection structure was produced in the same manner as in Example 1 except that the conductive particles A were changed to the obtained conductive particles D.

  In the obtained connection structure, the copper layer in the conductive particles D was in contact with the first and second electrodes, and the conductive particles D were in the state shown in FIG.

(Comparative Example 4)
(1) Production of conductive particles Copper particles having an average particle diameter of 3 μm were prepared. Using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), on the surface of the copper particles, solder fine powder (containing 42 wt% tin and 58 wt% bismuth, average particle size 0.5 μm) is melted, A solder layer having a thickness of 0.5 μm was formed on the surface of the copper particles.

  Thus, the electroconductive particle Y in which the solder layer (Tin: bismuth = 42 weight%: 58 weight%) is formed on the surface of a copper particle was produced. The melting point of the copper particles was 1084 ° C. The melting point of the solder layer (containing 42% by weight of tin) was 138 ° C.

(2) Production of anisotropic conductive paste and connection structure An anisotropic conductive paste and connection structure were obtained in the same manner as in Example 1 except that the conductive particles A were changed to the obtained conductive particles Y. Was made.

  In the obtained connection structure, the solder layer was melted and solidified after wetting and spreading on the surface of the second electrode. In the obtained connection structure, the copper layer was in contact with the second electrode, and the conductive particles Y were in the state shown in FIG. With respect to the center line passing through the center of the resin particle in the conductive particle Y, the solder layer is unevenly distributed up and down asymmetrically, and 75% by volume of the solder layer is present in the region below the center line ( A part of the solder layer also exists in the upper region (not shown)). Moreover, the solder layer was unevenly distributed with respect to the center line.

(Evaluation)
(1) Insulation test between electrodes adjacent in the lateral direction In the obtained connection structure, the presence or absence of leakage between adjacent electrodes was evaluated by measuring resistance with a tester. When the resistance exceeded 500 MΩ, it was determined that there was no leakage, and the result was “◯”. When the resistance was 500 MΩ or less, the result was determined as having leakage, and the result was determined as “X”.

(2) Conduction test between upper and lower electrodes The connection resistance between the upper and lower electrodes of the obtained connection structure was measured by a four-terminal method. The average value of 10 connection resistances 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 continuity test between the upper and lower electrodes was determined according to the following criteria.

[Criteria for continuity test between upper and lower electrodes]
○: The average value of connection resistance is 2Ω or less △: The average value of connection resistance exceeds 2Ω, 4Ω or less ×: The average value of connection resistance exceeds 4Ω

(3) Thermal shock characteristics Process of preparing 20 each of the obtained connection structures, holding at −20 ° C. for 30 minutes, then raising the temperature to 80 ° C., holding for 30 minutes, and then lowering the temperature to −30 ° C. A cold cycle test was carried out with 1 cycle. Ten connection structures were taken out after 500 cycles and 1000 cycles, respectively.

  About 10 connection structures after the 500 cycles and 1000 cycles of the thermal cycle test, whether or not poor conduction between the upper and lower electrodes occurred was evaluated. Of the 10 connecting structures, “◯◯” indicates that the number of defective conduction is 0, and “◯” indicates that the number of defective conduction is one, 2 to 3 The case of “Δ” was judged as “Δ”, the case of four or more was judged as “×”, and the unrated was judged as “−”.

  The results are shown in Table 1 below. In Table 1 below, “−” indicates that evaluation is not performed.

DESCRIPTION OF SYMBOLS 1 ... Connection structure 2 ... 1st connection object member 2a ... Upper surface 2b ... 1st electrode 3 ... Connection part 3a ... Upper surface 3A ... Anisotropic conductive material layer 4 ... 2nd connection object member 4a ... Lower surface 4b ... 2nd electrode 21 ... Conductive particle 21A-21C ... Conductive particle 22 ... Resin particle 22a ... Surface 23 ... 1st conductive layer 23a ... Surface 24 ... 2nd conductive layer 24A-24C ... 2nd conductive layer 31 ... Conductive particles 32 ... First conductive layer 32a ... Surface 32A ... Inner first conductive layer 32B ... Outer first conductive layer 33 ... Second conductive layer

Claims (10)

A first connection object member having a first electrode on its upper surface;
A second connection target member having a second electrode on the lower surface;
A connection portion that is disposed between an upper surface of the first connection target member and a lower surface of the second connection target member and is formed of an anisotropic conductive material including conductive particles;
The first and second electrodes are electrically connected by the conductive particles;
The conductive particles are resin particles, a first conductive layer disposed on the surface of the resin particles, and the first conductive layer disposed on the outer surface of the first conductive layer. A second conductive layer having a lower melting point than
In the state where the first connection target member is disposed on the lower side, the second connection target member is disposed on the upper side, and the first and second connection target members are disposed such that the main surface is horizontal, With respect to the center line passing through the center of the resin particles in the conductive particles electrically connected to the second electrode, the second conductive layer is unevenly distributed in an up-and-down asymmetric manner with respect to the center line. A connection structure in which 70% by volume or more and 100% by volume or less of the second conductive layer is present in an upper region or a region lower than the center line. When the linear expansion coefficient of the first connection target member is larger than the linear expansion coefficient of the second connection target member, 70 volumes of the second conductive layer are formed in a region below the center line. % To 100% by volume,
When the linear expansion coefficient of the second connection target member is larger than the linear expansion coefficient of the first connection target member, 70% by volume of the second conductive layer in the region above the center line. The connection structure according to claim 1, wherein 100% by volume or less is present.   The first conductive layer in the conductive particles electrically connecting the first and second electrodes is in contact with the first electrode and the second electrode. Or the connection structure of 2.   The connection structure according to claim 1, wherein the melting point of the second conductive layer is 50 ° C. or lower than the melting point of the outermost layer of the first conductive layer.   The connection structure according to claim 4, wherein the melting point of the second conductive layer is 100 ° C. or more and 250 ° C. or less, and the melting point of the outermost layer of the first conductive layer is 300 ° C. or more. Disposing an anisotropic conductive material layer using an anisotropic conductive material containing conductive particles on a first connection target member having a first electrode on an upper surface;
Laminating a second connection target member having a second electrode on the lower surface on the upper surface of the anisotropic conductive material layer;
Forming a connection portion with the anisotropic conductive material layer, and electrically connecting the first electrode and the second electrode with the conductive particles,
As the conductive particles, resin particles, a first conductive layer disposed on the surface of the resin particles, a first conductive layer disposed on the outer surface of the first conductive layer, and the first conductive layer Using conductive particles having a second conductive layer having a lower melting point than
In the state where the first connection target member is disposed on the lower side, the second connection target member is disposed on the upper side, and the first and second connection target members are disposed such that the main surface is horizontal, The second conductive layer is located above the center line so that the second conductive layer is asymmetrically distributed in the vertical direction with respect to the center line passing through the center of the resin particle in the conductive particle electrically connecting the second electrode. The first electrode and the second electrode are formed by the conductive particles so that 70% by volume or more and 100% by volume or less of the second conductive layer exists in a region below the center line or a region below the center line. The manufacturing method of the connection structure which electrically connects with the electrode of. When the linear expansion coefficient of the first connection target member is larger than the linear expansion coefficient of the second connection target member, 70 volumes of the second conductive layer are formed in a region below the center line. %, And the first electrode and the second electrode are electrically connected by the conductive particles so that there is 100% by volume or less.
When the linear expansion coefficient of the second connection target member is larger than the linear expansion coefficient of the first connection target member, 70% by volume of the second conductive layer in the region above the center line. The manufacturing method of the connection structure according to claim 6, wherein the first electrode and the second electrode are electrically connected by the conductive particles so that 100% by volume or less exists.   By the conductive particles, the first conductive layer in the conductive particles electrically connecting the first and second electrodes is in contact with the first electrode and the second electrode. The manufacturing method of the connection structure of Claim 6 or 7 which electrically connects a said 1st electrode and a said 2nd electrode.   9. The conductive particle according to claim 6, wherein the conductive particle is a conductive particle whose melting point of the second conductive layer is lower by 50 ° C. or more than the melting point of the outermost layer of the first conductive layer. The manufacturing method of the connection structure of description.   As the conductive particles, conductive particles in which the melting point of the second conductive layer is 100 ° C. or higher and 250 ° C. or lower and the melting point of the outermost layer of the first conductive layer is 300 ° C. or higher are used. Item 10. A method for manufacturing a connection structure according to Item 9.