JP2013258139A - Conductive material, connection structure and method for producing connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive material capable of efficiently disposing conductive particles on electrodes each having an external surface formed of a material having a thermal conductivity of 200 W/m K, when the electrodes are electrically connected.SOLUTION: A conductive material according to the present invention is used for the electrical connection of electrodes each having an external surface formed of a material having a thermal conductivity of 200 W/m K or more. The conductive material according to the present invention includes a binder resin and conductive particles 1 each having solder on a conductive surface thereof. The conductive material according to the present invention has a thermal conductivity of 0.3 W/m K or less. The conductive material according to the present invention has a minimum melt viscosity of 70 Pa s or less at 40-100°C.

Description

  The present invention relates to a conductive material used for electrical connection between electrodes such as a flexible printed circuit board, a glass substrate, a semiconductor chip, and a glass epoxy substrate. The present invention also relates to a connection structure using the conductive material.

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

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

  For example, when the electrode of the semiconductor chip and the electrode of the glass substrate are electrically connected by the anisotropic conductive material, an anisotropic conductive material containing conductive particles is disposed on the glass substrate. Next, the semiconductor chips are stacked, and heated and pressurized. As a result, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

  As an example of the anisotropic conductive material, the following Patent Document 1 discloses an anisotropic conductive material including an adhesive composition that flows by heating, first particles, and second particles. Yes. The first particle has a core mainly composed of a low melting point metal having a melting point of 130 to 250 ° C., and a resin composition that covers the surface of the core and has a softening point lower than the melting point of the low melting point metal. And an insulating layer formed by. The second particle has an average particle size smaller than that of the core in the first particle. The main component of the second particle is a material having a melting point or a softening point higher than the melting point of the low melting point metal.

JP 2009-277852 A

  When an anisotropic conductive material containing conventional conductive particles as described in Patent Document 1 is used for connection between electrodes, it is difficult to efficiently arrange a plurality of conductive particles between the electrodes. Sometimes. There is a problem that the conductive particles are easily arranged not only in the line (L) where the electrode is formed but also in the space (S) where the electrode is not formed. For this reason, many conductive particles may have to be used on the assumption that the conductive particles are also arranged in the space. Furthermore, there is a problem that poor insulation is likely to occur as a result of the conductive particles being arranged in the space.

  An object of the present invention is to efficiently dispose conductive particles on an electrode when an electrode having an outer surface formed of a material having a thermal conductivity of 200 W / m · K is electrically connected. It is to provide a conductive material that can be formed, and a connection structure using the conductive material.

  According to a wide aspect of the present invention, there is provided a conductive material used for electrical connection of an electrode having an outer surface formed of a material having a thermal conductivity of 200 W / m · K or more, wherein the solder is electrically conductive. Provided is a conductive material comprising conductive particles on the surface and a binder resin, having a thermal conductivity of 0.3 W / m · K or less and a minimum melt viscosity at 40 to 100 ° C. of 70 Pa · s or less. The

  The conductive particles preferably have a particle size of 0.5 μm or more and 30 μm or less. The conductive particles are preferably solder particles.

  The conductive material according to the present invention is preferably a conductive material used for electrical connection of an electrode having an outer surface formed of a material having a thermal conductivity of 300 W / m · K or more. In the conductive material according to the present invention, the material having the thermal conductivity of 300 W / m · K or more is preferably gold, silver, or copper. The conductive particles may include base material particles and a solder layer disposed on the surface of the base material particles.

  According to a wide aspect of the present invention, a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, and the A connecting portion connecting to a second connection target member, wherein the connecting portion is formed of the conductive material described above, and at least one of the first electrode and the second electrode is The outer surface is formed of a material having a thermal conductivity of 200 W / m · K or more, and the first electrode and the second electrode are electrically connected by the conductive particles. A connection structure is provided.

  According to a wide aspect of the present invention, the step of disposing the above-described conductive material on the first connection target member having the first electrode on the surface, and the first connection target member side of the conductive material are Disposing a second connection target member having a second electrode on the surface on the opposite surface, heating the conductive material to 120 to 220 ° C., and using the conductive material, the first connection target member And connecting the second connection target member to form a connection portion, and after the step of disposing the conductive particles to before the step of forming the connection portion, the conductive material A material having a thermal conductivity of 200 W / m · K or more, wherein at least one of the first electrode and the second electrode is further heated to a temperature at which the melt viscosity becomes 70 Pa · s or less. The outer surface is formed by the first electrode And the second electrode to obtain a connection structure that is electrically connected by the conductive particles, the manufacturing method of the connecting structure is provided.

  In the connection structure according to the present invention and the method for manufacturing the connection structure according to the present invention, at least one of the first electrode and the second electrode has a thermal conductivity of 300 W / m · K or more. The outer surface is preferably formed of a material. In the connection structure according to the present invention and the method for manufacturing the connection structure according to the present invention, the material having a thermal conductivity of 300 W / m · K is preferably gold, silver, or copper.

  The conductive material according to the present invention includes conductive particles having a solder on a conductive surface and a binder resin, wherein the conductive material has a thermal conductivity of 0.3 W / m · K or less, and further 40 to 40 of the conductive material. Since the minimum melt viscosity at 100 ° C. is 70 Pa · s or less, an electrode having an outer surface formed of a material having a thermal conductivity of 200 W / m · K or more is electrically formed using the conductive material according to the present invention. When connected to, the conductive particles can be efficiently arranged on the electrode.

FIG. 1 is a front sectional view schematically showing a connection structure using a conductive material according to an embodiment of the present invention. FIG. 2 is a front cross-sectional view schematically showing an enlarged connection portion between conductive particles and electrodes in the connection structure shown in FIG. 1. FIG. 3 is a cross-sectional view showing an example of conductive particles that can be used in the conductive material according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a modification of the conductive particles. FIG. 5 is a cross-sectional view showing another modified example of conductive particles.

  Details of the present invention will be described below.

  The conductive material according to the present invention is used for electrical connection of electrodes having an outer surface formed of a material having a thermal conductivity of 200 W / m · K or more. The conductive material according to the present invention includes conductive particles having solder on a conductive surface and a binder resin. The thermal conductivity of the conductive material according to the present invention is 0.3 W / m · K or less. The minimum melt viscosity at 40 to 100 ° C. of the conductive material according to the present invention is 70 Pa · s or less.

  By adopting the above-described configuration in the conductive material according to the present invention, the conductive particles can be efficiently arranged on the electrode. Moreover, when obtaining a connection structure, the electroconductive particle which is not located on an electrode can be effectively moved on an electrode. The reason for this is that when the conductive material is heated, the thermal conductivity of the electrode surface is high and the conductive material has a low thermal conductivity. Since the melt viscosity is lower than the melt viscosity of the conductive material in the region, the conductive particles are likely to collect on the electrode. In addition, even if the temperature of the conductive material in the region near the electrode rises, the amount of heat is not easily transferred to the conductive material in other regions other than the vicinity of the electrode. And the conductive particles are difficult to move from a region near the electrode having a particularly low melt viscosity to another region. Furthermore, since the minimum melt viscosity at 40 to 100 ° C. of the conductive material is 70 Pa · s or less, the melt viscosity of the conductive material in the region in the vicinity of the electrode is sufficiently low, so that conductive particles tend to collect in the vicinity of the electrode. Can be mentioned. In addition, the temperature range which prescribes | regulates minimum melt viscosity was set to 40-100 degreeC because the movement to the electrode of the electroconductive particle at the time of a heating progresses easily at 40-100 degreeC especially. These effects were found for the first time by the present inventors.

  Moreover, in the conductive material according to the present invention, as a result of being able to efficiently arrange the conductive particles on the electrode, on the premise that the conductive particles are also arranged in the space (S) of the portion where the electrode is not formed, Since it is not necessary to use a large amount of conductive particles, the amount of conductive particles used can be reduced.

  In recent years, with the downsizing of electronic devices, the distance between the line (L) where the electrode is formed and the space (S) where the electrode is not formed has become narrower. For example, there is an increasing need to electrically connect fine electrodes having L / S of 100 μm or less / 100 μm or less. When electrically connecting electrodes having a small L / S, the conventional anisotropic conductive material has a problem that insulation defects are particularly likely to occur because many conductive particles are easily arranged in the space (S). is there.

  On the other hand, the use of the conductive material according to the present invention makes it difficult for the conductive particles to be disposed in the space (S), and it is possible to effectively suppress the occurrence of insulation failure.

  In the conductive material according to the present invention, in particular, L / S indicating the line (L) where the electrode is formed and the space (S) where the electrode is not formed is 100 μm or less / 100 μm or less. In this case, the insulation reliability can be effectively increased, and when L / S is 75 μm or less / 75 μm or less, the insulation reliability can be further effectively improved, and L / S is 62.5 μm. In the case of ≦ 62.5 μm or less, the insulation reliability can be further effectively increased, and in the case where L / S is 50 μm or less / 50 μm or less, the insulation reliability is particularly effectively increased. it can.

  Further, since the conduction reliability can be improved by the conductive material according to the present invention, the line (L) where the electrode is formed is preferably 100 μm or less, more preferably 75 μm or less, and even more preferably 62.5 μm. Hereinafter, it is particularly preferably 50 μm or less. The line (L) is preferably larger than the particle size (volume average particle size) of the conductive particles, more preferably 1.1 times or more of the particle size of the conductive particles, and 2 times or more. Is more preferable, and it is particularly preferably 3 times or more.

  Further, when heating a conductive material containing conductive particles and a binder resin, a method of arranging a conductive particle on the electrode by generating a gas in the conductive material and convection in the binder resin. Can be considered. However, in this method, a gas (void) is included in the connection portion formed of the conductive material. As a result, the connection resistance between the electrodes is lowered, and the connection reliability is lowered.

  On the other hand, by using the conductive material according to the present invention, the conductive particles can be efficiently arranged on the electrode without generating gas in the conductive material. In addition, it is possible to suppress the generation of voids in the connection portion formed of the conductive material. As a result, the connection resistance between the electrodes can be lowered, and the connection reliability can be increased.

  In the conductive material according to the present invention, it is preferable not to generate a gas, it is preferable that the gas does not convection in the binder resin, and the conductive particles do not dispose conductive particles on the electrode by convection in the binder resin. preferable.

  Further, in the conductive material according to the present invention, since the conductive surface of the conductive particles is solder, it is possible to wet and spread the solder on the electrode surface. Reliability can be increased. In addition, when the conductive surface of the conductive particles is solder, the thermal conductivity of the conductive material can be effectively lowered due to the conductive particles. Furthermore, the conductive particles can be accurately fixed at a predetermined position by the solder solidified after being melted. This also makes it possible to efficiently dispose the conductive particles on the electrode.

  In order to efficiently dispose the conductive particles on the electrode, the present inventors have 1) an electrode having an outer surface formed of a material having a thermal conductivity of 200 W / m · K or more. 2) The conductive particles contained in the conductive material are conductive particles having solder on the conductive surface. 3) The thermal conductivity of the conductive material is 0.3 W / It has been found that it must be satisfied by combining all the structural requirements that it is not more than m · K, and 4) the minimum melt viscosity at 40 to 100 ° C. of the conductive material is not more than 70 Pa · s.

  Examples of the material having a thermal conductivity of 200 W / m · K or more on the surface of the electrode include gold (thermal conductivity 320 W / m · K), silver (thermal conductivity 420 W / m · K), copper (thermal conductivity). 398 W / m · K) and aluminum (thermal conductivity 236 W / m · K). Among these, from the viewpoint of further lowering the connection resistance or making it more difficult for the electrode to corrode, the material having a thermal conductivity of 200 W / m · K or more is gold, silver, copper or aluminum. Preferably there is.

  From the viewpoint of more efficiently disposing the conductive particles on the electrode, the conductive material is used for electrical connection of an electrode whose outer surface is formed of a material having a thermal conductivity of 300 W / m · K or more. It is preferable to be used. From the viewpoint of more efficiently disposing the conductive particles on the electrode, the material having a thermal conductivity of 300 W / m · K or more is preferably gold, silver, or copper.

  From the viewpoint of more efficiently arranging the conductive particles on the electrode, the conductive material is used for electrical connection of an electrode whose outer surface is formed of a material having a thermal conductivity of 350 W / m · K or more. It is preferable to be used. From the viewpoint of more efficiently disposing the conductive particles on the electrode, the material having the thermal conductivity of 350 W / m · K or more is preferably copper or silver.

  From the viewpoint of more efficiently disposing the conductive particles on the electrode, the conductive material is used for electrical connection of an electrode whose outer surface is formed of a material having a thermal conductivity of 400 W / m · K or more. It is preferable to be used. From the viewpoint of more efficiently disposing the conductive particles on the electrode, the material having the thermal conductivity of 400 W / m · K or more is preferably silver.

  The electrode having an outer surface formed of a material having a thermal conductivity of 300 W / m · K or more is, for example, a first electrode formed of a material having a thermal conductivity of less than 300 W / m · K. An electrode in which a second electrode formed of a material having a thermal conductivity of 300 W / m · K or more is disposed on the surface. For example, an electrode in which a second electrode formed of gold, silver, copper, aluminum, or the like is disposed on the surface of a first electrode (nickel electrode) formed of nickel may be used.

  The conductive material has a thermal conductivity of 0.3 W / m · K or less. From the viewpoint of more efficiently disposing the conductive particles on the electrode, the thermal conductivity of the conductive material is preferably 0.27 W / m · K or less, more preferably 0.25 W / m · K or less. . The lower the thermal conductivity of the conductive material, the better.

  The thermal conductivity of the conductive material can be easily adjusted by reducing the blending amount of the blending component with high thermal conductivity or increasing the blending amount of the blending component with low thermal conductivity. . For example, the thermal conductivity of the conductive material can be further reduced by not using the thermal conductive filler or by reducing the amount of the thermal conductive filler used. The conductive material does not include a filler having a thermal conductivity of 10 W / m · K or more, or in 100 wt% of the conductive material, a filler having a thermal conductivity of 10 W / m · K or more is 35 wt% or less. It is preferable to include. The smaller the content of the filler having a thermal conductivity of 10 W / m · K or more, the better. In the present specification, the thermally conductive filler does not include the conductive particles for electrically connecting the electrodes. Moreover, in order to control the heat conductivity of the said electrically-conductive material, the compounding quantity of the said electroconductive particle can be suitably adjusted with the compounding quantity of the said heat conductive filler.

  The minimum melt viscosity at 40 to 100 ° C. of the conductive material is 70 Pa · s or less. From the viewpoint of more efficiently disposing the conductive particles on the electrode, the minimum melt viscosity at 40 to 100 ° C. of the conductive material is preferably 50 Pa · s or less, more preferably 10 Pa · s or less, and even more preferably 1 Pa. -S or less.

  The minimum melt viscosity can be easily adjusted by selecting a blending component. However, in this invention, the minimum melt viscosity in 40-100 degreeC of the said electrically conductive material is set low, and it is set to 70 Pa.s or less. In order to make the minimum melt viscosity at 40 to 100 ° C. of the conductive material 70 Pa · s or less, the blending components can be appropriately adjusted.

  The minimum melt viscosity is determined by measuring the minimum complex viscosity η * using a rheometer. The measurement conditions are strain control 1 rad, frequency 1 Hz, temperature increase rate 20 ° C./min, and measurement temperature range 40 to 100 ° C.

  The ratio η * 1 / η * 2 of the viscosity η * 1 at 40 ° C. and the viscosity η * 2 at 100 ° C. is preferably 5 or more, and more preferably 7 or more. When the ratio η * 1 / η * 2 is equal to or greater than the above lower limit, the difference in viscosity between the conductive material of the electrode portion and the other portion (portion other than the electrode portion) becomes appropriate, and the conductive particles are on the electrode. Makes it easier to gather.

  Examples of the rheometer include STRESTTECH (manufactured by EOLOGICA).

  The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, particularly preferably 5 μm or more, preferably 100 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. Particularly preferably, it is 15 μm or less, and most preferably 10 μm or less. When the particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conductive particles can be more efficiently arranged on the electrode. From the viewpoint of more efficiently arranging the conductive particles on the electrode, the particle diameter of the conductive particles is particularly preferably 3 μm or more and 30 μm or less.

  The “particle diameter” of the conductive particles is a volume average particle diameter obtained from a volume distribution measured by a laser diffraction particle size distribution measuring device. For example, the volume average particle diameter of the conductive particles can be measured using a laser diffraction particle size distribution analyzer (“LA-920” manufactured by Horiba, Ltd.).

  The CV value of the volume particle diameter of the conductive particles is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less. If the CV value is less than or equal to the above upper limit, higher insulation reliability can be obtained.

  The CV value of the particle diameter is expressed by the following formula.

  CV value of particle diameter (%) = standard deviation of particle diameter / average particle diameter × 100

  The d90 in the particle size distribution on the volume basis of the conductive particles is preferably not more than 3 times the volume average particle size of the conductive particles, more preferably not more than 2 times the volume average particle size of the conductive particles. d90 is the particle diameter of the conductive particles when the cumulative volume of the conductive particles is 90% in the particle size distribution on the volume basis. When the d90 and the volume particle diameter of the conductive particles satisfy the above-described preferable relationship, the insulation reliability is further enhanced.

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

(Conductive particles)
As the conductive particles according to the present invention, it is possible to use solder particles, particles including substrate particles and a solder layer disposed on the surface of the substrate particles. Among these, it is preferable to use solder particles. By using solder particles, high-speed transmission and metal bonding strength can be further improved.

  FIG. 3 is a cross-sectional view showing an example of conductive particles that can be used in the conductive material according to an embodiment of the present invention. As shown in FIG. 3, the solder particles are preferably conductive particles 21 that are solder particles. The conductive particles 21 are formed only by solder. The conductive particles 21 do not have base particles in the core and are not core-shell particles. As for the electroconductive particle 21, both a center part and an outer surface are formed with the solder.

  From the viewpoint of more uniformly maintaining the connection distance between the substrates, particles including base particles and a solder layer disposed on the surface of the base particles may be used.

  In the modification shown in FIG. 4, the conductive particle 1 includes a base particle 2 and a conductive layer 3 disposed on the surface of the base particle 2. The conductive layer 3 covers the surface of the base particle 2. The conductive particle 1 is a coated particle in which the surface of the base particle 2 is coated with the conductive layer 3.

  The conductive layer 3 includes a second conductive layer 3A and a solder layer 3B (first conductive layer) disposed on the surface of the second conductive layer 3A. The conductive particle 1 includes a second conductive layer 3A between the base particle 2 and the solder layer 3B. Therefore, the conductive particles 1 include the base particle 2, the second conductive layer 3A disposed on the surface of the base particle 2, and the solder layer 3B disposed on the surface of the second conductive layer 3A. Is provided. Thus, the conductive layer 3 may have a multilayer structure, or may have a laminated structure of two or more layers.

  As described above, the conductive layer 3 in the conductive particle 1 has a two-layer structure. As in another modification shown in FIG. 5, the conductive particles 11 may have a solder layer 12 as a single conductive layer. The conductive particles 11 include base material particles 2 and a solder layer 12 disposed on the surface of the base material particles 2. The solder layer 12 may be disposed on the surface of the base particle 2 so as to contact the base particle 2.

  Of the conductive particles 1, 11, and 21, the conductive particles 1, 11 are more preferable because the thermal conductivity of the conductive material tends to be further lowered. By using conductive particles including base particles and a solder layer disposed on the surface of the base particles, it is easy to further reduce the thermal conductivity of the conductive material.

  Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. From the viewpoint of more efficiently disposing the conductive particles on the electrode, the base particles are preferably base particles excluding metal, and are resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. Preferably there is. The substrate particles may be copper particles.

  The substrate particles are preferably resin particles formed of a resin. When connecting between electrodes using electroconductive particle, after arrange | positioning electroconductive particle between electrodes, electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles, the conductive particles are easily deformed during the pressure bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes still higher.

  Various organic materials are suitably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, Polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamide Bromide, polyether ether ketone, polyether sulfone, divinyl benzene polymer, and divinylbenzene copolymer, and the like. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid ester copolymer. Since the hardness of the resin particles can be easily controlled within a suitable range, the resin for forming the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. It is preferably a coalescence.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having the ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer. And a polymer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Esters; Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; Halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Is mentioned.

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanurate, tria Rutorimeriteto, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, .gamma. (meth) acryloxy propyl trimethoxy silane, trimethoxy silyl styrene, include silane-containing monomers such as vinyltrimethoxysilane.

  In the case where the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal, examples of the inorganic material for forming the substrate particles include silica and carbon black. Although it does not specifically limit as the particle | grains formed with the said silica, For example, after hydrolyzing the silicon compound which has two or more hydrolysable alkoxysil groups, and forming a crosslinked polymer particle, it calcinates as needed. The particle | grains obtained by performing are mentioned. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  When the substrate particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium. When the base material particles are metal particles, the metal particles are preferably copper particles. However, the substrate particles are preferably not metal particles.

  The method for forming the conductive layer on the surface of the base particle and the method for forming the solder layer on the surface of the base particle or the surface of the second conductive layer are not particularly limited. As a method of forming the conductive layer and the solder layer, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, And a method of coating the surface of the substrate particles with a paste containing metal powder or metal powder and a binder. Among these, a method using electroless plating, electroplating, or physical collision is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method based on the physical collision, for example, a sheeter composer (manufactured by Tokuju Kogakusha Co., Ltd.) or the like is used.

  The melting point of the base particle is preferably higher than the melting point of the solder layer. The melting point of the substrate particles is preferably higher than 160 ° C, more preferably higher than 300 ° C, still more preferably higher than 400 ° C, and particularly preferably higher than 450 ° C. The melting point of the substrate particles may be less than 400 ° C. The melting point of the substrate particles may be 160 ° C. or less. The softening point of the substrate particles is preferably 260 ° C. or higher. The softening point of the substrate particles may be less than 260 ° C.

  The conductive particles may have a single solder layer. The conductive particles may have a plurality of conductive layers (solder layer, second conductive layer). That is, in the conductive particles, two or more conductive layers may be stacked. In some cases, the solder particles may be particles formed of a plurality of layers. Hereinafter, the solder forming the solder particles may also be referred to as a solder layer.

  The solder for forming the solder layer and the solder for forming solder particles are preferably low melting point metals having a melting point of 450 ° C. or lower. The solder layer is preferably a low melting point metal layer having a melting point of 450 ° C. or lower. The low melting point metal layer is a layer containing a low melting point metal. The solder 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 layer and the solder particles preferably contain tin. In 100% by weight of the metal contained in the solder layer and 100% by weight of the metal contained in the solder particles, the tin content is preferably 30% by weight or more, more preferably 40% by weight or more, and even more preferably 70% by weight. Above, particularly preferably 90% by weight or more. When the content of tin in the solder layer and the solder particles is equal to or higher than the lower limit, the connection reliability between the conductive particles and the electrodes 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 and the conductive particles having the solder on the conductive surface, the solder is melted and joined to the electrodes, and the solder conducts between the electrodes. For example, since the solder and the electrode are not in point contact but in surface contact, the connection resistance is lowered. In addition, the use of conductive particles having solder on the conductive surface increases the bonding strength between the solder and the electrode. As a result, peeling between the solder and the electrode is further less likely to occur, and conduction reliability and connection reliability are improved. Effectively high.

  The low melting point metal constituting the solder layer and the solder particles is not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. Examples of the alloy include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, a tin-zinc alloy, and a tin-indium alloy. Especially, since it is excellent in the wettability with respect to an electrode, it is preferable that the said low melting metal is a tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, and a tin-indium alloy. More preferred are a tin-bismuth alloy and a tin-indium alloy.

  The material constituting the solder (solder layer and solder particles) is 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 include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. Among them, a tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic) which is low-melting and lead-free is preferable. That is, the solder preferably does not contain lead, and is preferably a solder containing tin and indium or a solder containing tin and bismuth.

  In order to further increase the bonding strength between the solder and the electrode, the solder layer and the solder particles are nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, Metals such as manganese, chromium, molybdenum, and palladium may be included. Moreover, from the viewpoint of further increasing the bonding strength between the solder and the electrode, the solder layer and the solder particles preferably contain nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further increasing the bonding strength between the solder layer or solder particles and the electrode, the content of these metals for increasing the bonding strength is 100 wt% of the solder layer or 100 wt% of the solder particles, preferably 0. 0.0001% by weight or more, preferably 1% by weight or less.

  The melting point of the second conductive layer is preferably higher than the melting point of the solder layer. The melting point of the second conductive layer is preferably above 160 ° C, more preferably above 300 ° C, even more preferably above 400 ° C, even more preferably above 450 ° C, particularly preferably above 500 ° C, most preferably Preferably it exceeds 600 degreeC. Since the solder layer has a low melting point, it melts during conductive connection. The second conductive layer is preferably not melted at the time of conductive connection. The conductive particles are preferably used after melting solder, preferably used after melting the solder layer, and used without melting the second conductive layer while melting the solder layer. It is preferred that Since the melting point of the second conductive layer is higher than the melting point of the solder layer, only the solder layer can be melted without melting the second conductive layer at the time of conductive connection.

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

  The second conductive layer preferably contains a metal. The metal constituting the second conductive layer is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and alloys thereof. Further, tin-doped indium oxide (ITO) may be used as the metal. As for the said metal, only 1 type may be used and 2 or more types may be used together.

  The second conductive layer is preferably a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably a nickel layer or a gold layer, and even more preferably a copper layer. The conductive particles preferably have a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably have a nickel layer or a gold layer, and still more preferably have a copper layer. By using the conductive particles having these preferable conductive layers for the connection between the electrodes, the connection resistance between the electrodes is further reduced. In addition, a solder layer can be more easily formed on the surface of these preferable conductive layers.

  When the conductive particles are solder particles (having no base particles), the solder particles are preferably a filler material having a liquidus of 450 ° C. or lower based on JIS Z3001: Welding terms. . Examples of the composition of the solder include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. Among them, a tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic) which is low-melting and lead-free is preferable. That is, the solder preferably does not contain lead, and is preferably a solder containing tin and indium or a solder containing tin and bismuth.

  The thickness of the solder layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. When the thickness of the solder layer is not less than the above lower limit and not more than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed at the time of connection between the electrodes. . Further, the thinner the solder layer is, the easier it is to lower the thermal conductivity of the conductive material. From the viewpoint of sufficiently reducing the thermal conductivity of the conductive material, the thickness of the solder layer is preferably 4 μm or less, more preferably 2 μm or less.

  The thickness of the second conductive layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 0.3 μm or less. When the thickness of the second conductive layer is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes is further reduced. In addition, the thinner the second conductive layer is, the easier it is to reduce the thermal conductivity of the conductive material. From the viewpoint of sufficiently reducing the thermal conductivity of the conductive material, the thickness of the second conductive layer is preferably 3 μm or less, more preferably 1 μm or less.

  When the conductive particles have only a solder layer as a conductive layer, the thickness of the solder layer is preferably 10 μm or less, more preferably 5 μm or less. When the conductive particles have a conductive layer different from the solder layer and the other conductive layer (such as the second conductive layer) as the conductive layer, the solder layer and the other conductive layer different from the solder layer The total thickness is preferably 10 μm or less, more preferably 5 μm or less.

(Conductive material)
The conductive material according to the present invention includes the conductive particles and a binder resin. The conductive material according to the present invention includes a plurality of the conductive particles. The conductive material according to the present invention is preferably an anisotropic conductive material.

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

  Examples of the compound that can be cured by heating include an epoxy compound, a (meth) acrylic compound, an episulfide compound, and an oxetane compound. Of these, epoxy compounds and episulfide compounds are preferred from the viewpoint of further improving connection reliability.

  The conductive material and the binder resin may contain a thermoplastic component (thermoplastic compound). When the conductive material according to the present invention is a conductive film, the conductive material and the binder resin preferably include a thermoplastic component, and more preferably include a phenoxy resin, in order to improve the film formability. The thermoplastic compound may have a reactive functional group.

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

  From the viewpoint of more efficiently arranging the conductive particles on the electrode, the binder resin may not be cured in a heating time of 2 seconds when the conductive material is heated to the melting point of the solder in the conductive particles. preferable. From the viewpoint of more efficiently disposing the conductive particles on the electrode, the binder resin is cured in a heating time exceeding 2 seconds when the conductive material is heated to the melting point of the solder in the conductive particles + 30 ° C. It is preferable to cure with a heating time of 3 seconds or more, and it is preferable to cure with a heating time of about 5 seconds. Whether or not the conductive material is cured is determined as follows.

  A conductive material is sandwiched between polyimide films having a thickness of 50 μm so as to have a thickness of 50 μm to obtain a laminate, and the obtained laminate is placed on a hot plate set at a solder melting point + 30 ° C. Heat in time. 2 mg of conductive material between polyimides was sampled, and 10 ° C / 10 ° C in a temperature range from room temperature (23 ° C) to 300 ° C using a differential scanning calorimeter ("EXSTAR X-DSC7000" manufactured by Hitachi High-Tech Science Co., Ltd.). The amount of heat generated during curing is measured at a heating rate of minutes. When the heating value of the unheated conductive material is 100, it is determined that the conductive material heated by the hot plate is not cured when the heating value is 50 or more, more preferably 70 or more.

  From the viewpoint of more efficiently disposing the conductive particles on the electrode, the curable compound curable by heating is preferably an epoxy compound. From the viewpoint of more efficiently arranging the conductive particles on the electrode, the molecular weight of the epoxy compound is preferably 200 or more, more preferably 300 or more, preferably 2000 or less, more preferably 1000 or less. The molecular weight means a molecular weight that can be calculated from the structural formula when the epoxy compound is not a polymer and when the structural formula of the epoxy compound can be specified. Moreover, when the said epoxy compound is a polymer, a weight average molecular weight is meant.

  Moreover, when using thermosetting agents other than a thermal cation hardening agent, it is preferable that the said curable compound which can be hardened | cured by heating has an aromatic skeleton. From the viewpoint of more efficiently arranging the conductive particles on the electrode, the thermosetting agent is preferably a thermal cation initiator. From the viewpoint of more efficiently arranging the conductive particles on the electrode, the curable compound curable by heating preferably has an alicyclic skeleton when a thermal cation initiator is used.

  Examples of curable compounds that can be cured by heating and have an aromatic skeleton include resorcinol-type epoxy compounds, naphthalene-type epoxy compounds, fluorene-type epoxy compounds, glycidylamine-type epoxy compounds, and anthracene-type epoxy compounds. It is done. Examples of the curable compound curable by heating and having an alicyclic skeleton include polyether type epoxy compounds and hydrogenated bisphenol type epoxy compounds.

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, still more preferably 20% by weight or more, particularly preferably. Is 25% by weight or more, most preferably 30% by weight or more, preferably 80% by weight or less, more preferably 60% by weight or less, still more preferably 50% by weight or less, particularly preferably 45% by weight or less, and most preferably 35% 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, it is easy to arrange many conductive particles between the electrodes, and the conduction reliability is further enhanced. Moreover, since content, such as a thermosetting component, becomes moderate, the conduction | electrical_connection reliability between electrodes becomes still higher. From the viewpoint of further improving the conduction reliability, the content of the conductive particles is preferably large. From the viewpoint of more efficiently arranging the conductive particles on the electrode, the content of the conductive particles in the conductive material is preferably 10% by weight or more and 50% by weight or less, preferably 20% by weight or more, 40% by weight. More preferably, it is at most 25% by weight, more preferably at least 25% by weight and at most 35% by weight.

  Since it is easy to further reduce the thermal conductivity of the conductive material, the content of the conductive particles is preferably 30% by weight or less, more preferably 20% by weight or less in 100% by weight of the conductive material. is there. Since it is easy to further reduce the thermal conductivity of the conductive material, when the conductive particles are solder particles, the content of the solder particles is preferably 40% in 100% by weight of the conductive material. % Or less, more preferably 30% by weight or less. When the conductive particles include base particles and a solder layer disposed on the surface of the base particles, the content of the conductive particles is preferably 30% by weight or less in 100% by weight of the conductive material. More preferably, it is 20% by weight or less.

  The content of the binder resin, the content of the thermoplastic component, or the content of the thermosetting component in 100% by weight of the conductive material (when the thermoplastic component and the thermosetting component are used in combination, thermoplasticity The total content of the component and the thermosetting component) is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, preferably 99% by weight or less, more preferably 98% by weight. % Or less, more preferably 90% by weight or less, particularly preferably 80% by weight or less. From the viewpoint of further improving impact resistance, it is preferable that the content of the binder resin, the thermoplastic component, or the thermosetting component is large.

  Examples of the compound that can be cured by heating include an epoxy compound, a (meth) acrylic compound, an episulfide compound, and an oxetane compound. Of these, epoxy compounds and episulfide compounds are preferred from the viewpoint of further improving connection reliability.

  Among epoxy compounds and episulfide compounds, aromatic epoxy compounds are preferable, and resorcinol type epoxy compounds, naphthalene type epoxy compounds, and fluorene type epoxy compounds are particularly preferable. By using these epoxy compounds, the viscosity is easily lowered by applying temperature to the conductive material. This makes it easier for the conductive particles to collect on the electrode.

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

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

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

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

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

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

  The 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, based on 100 parts by weight of the curable compound that can be cured by heating. The amount is preferably 100 parts by weight or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is not less than the above lower limit, it is easy to sufficiently cure the conductive material. When the content of the thermosetting agent is not more than the above upper limit, it is difficult for an excess thermosetting agent that did not participate in curing after curing to remain, and the heat resistance of the cured product is further enhanced.

  The binder resin preferably contains a flux. 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. As for the said flux, only 1 type may be used and 2 or more types may be used together.

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

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

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

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

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

  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 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. After uniformly dispersing using a homogenizer or the like in the solvent, adding to the binder resin, kneading and dispersing with a planetary mixer or the like, and after diluting the binder resin with water or an organic solvent, Examples thereof include a method in which conductive particles are added and kneaded and dispersed with a planetary mixer or the like.

  The conductive material according to the present invention can be used as a conductive paste and a conductive film. When the conductive material according to the present invention is a conductive film, a film that does not include conductive particles may be laminated on a conductive film that includes conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

(Connection structure)
A connection structure can be obtained by connecting the connection target members using the conductive material described above.

  The connection structure connects a first connection target member having an electrode on the surface, a second connection target member having an electrode on the surface, and the first connection target member and the second connection target member. A connecting structure in which the connecting part is formed of the conductive material described above, and the first electrode and the second electrode are electrically connected by the conductive particles. It is preferable that In this connection structure, at least one of the first electrode and the second electrode has an outer surface made of a material having a thermal conductivity of 200 W / m · K or more.

  The first electrode may have an outer surface made of a material having a thermal conductivity of 200 W / m · K or more, and the second electrode has a thermal conductivity of 200 W / m · K or more. The outer surface may be formed of a material, and both the first electrode and the second electrode may be formed of a material having a thermal conductivity of 200 W / m · K or more. . From the viewpoint of more efficiently disposing the conductive particles on the surface of the electrode, both the first electrode and the second electrode are made of a material having a thermal conductivity of 200 W / m · K or more. Is preferably formed.

  Moreover, the manufacturing method of the said connection structure has the process of arrange | positioning the electrically conductive material mentioned above on the 1st connection object member which has a 1st electrode on the surface, and the said 1st connection object member side of the said conductive material. A step of disposing a second connection target member having a second electrode on the surface opposite to the surface, heating the conductive material to 120 to 220 ° C., and the first connection by the conductive material Connecting the target member and the second connection target member to form a connection portion, and after the step of arranging the conductive particles to before the step of forming the connection portion, A connection structure further comprising a step of heating the conductive material to a temperature at which the melt viscosity becomes 70 Pa · s or less, wherein the first electrode and the second electrode are electrically connected by the conductive particles. It is preferable to obtain In this connection structure manufacturing method, at least one of the first electrode and the second electrode has an outer surface made of a material having a thermal conductivity of 200 W / m · K or more. In this connection structure manufacturing method, the conductive material is preferably heated to a temperature at which the melt viscosity is 70 Pa · s or less, and more preferably heated to a temperature at which 50 Pa · s or less. The melt viscosity can be measured under the same measurement conditions as the minimum melt viscosity.

  The heating time from the start of heating until the conductive material reaches a temperature at which the melt viscosity becomes 70 Pa · s or less is preferably 0.5 seconds or more, more preferably 1 second or more, and even more preferably 2 seconds or more. , Preferably 10 seconds or less, more preferably 5 seconds or less. When the heating time is equal to or more than the lower limit, the conductive particles are more easily collected on the electrode. When the heating time is less than or equal to the above upper limit, curing of the thermosetting component is difficult to proceed excessively, and the adhesive strength is further increased after connection.

  The step of heating the conductive material to a temperature at which the melt viscosity is 70 Pa · s or less includes the step of placing the conductive material on the first connection target member having the first electrode on the surface, and then the conductive material. You may carry out before the process of arrange | positioning the 2nd connection object member which has a 2nd electrode on the surface on the surface opposite to the said 1st connection object member side of material. Simultaneously with the step of disposing the second connection target member having the second electrode on the surface opposite to the first connection target member side of the conductive material, the conductive material has a melt viscosity of 70 Pa · You may perform the process heated to the temperature used as s or less. Or after the process of arrange | positioning the 2nd connection object member which has a 2nd electrode on the surface on the surface opposite to the said 1st connection object member side of the said conductive material, the said conductive material is 120-220. Before the step of connecting the first connection target member and the second connection target member with the conductive material and forming the connection portion, the conductive material is melted at a viscosity of 70 Pa · You may perform the process heated to the temperature used as s or less. In this case, the heating for setting the melt viscosity of the conductive material to 70 Pa · s or less and the heating for setting the conductive material to 120 to 220 ° C. may be performed continuously. It is preferable to heat the conductive material so that the heating time until reaching the temperature at which the melt viscosity becomes 70 Pa · s or less after the start of heating is not less than the lower limit and not more than the upper limit.

In the method for manufacturing the connection structure, the conductive material is disposed between the first connection target member and the second connection target member to obtain a laminate, and then the laminate is heated and pressurized. It is preferable. The solder in the conductive particles is melted by heating and pressurization, and the electrodes are electrically connected by the conductive particles. Furthermore, when the binder resin includes a thermosetting component, the binder resin is thermoset, and the first and second connection target members are connected by the cured binder resin. The pressure of the said pressurization is about 9.8 * 10 < ⁴ > -4.9 * 10 < ⁶ > Pa. The temperature of the said heating is about 120-220 degreeC.

  FIG. 1 is a front sectional view schematically showing a connection structure using a conductive material according to an embodiment of the present invention. The conductive material used here includes conductive particles 1 and a binder resin. Instead of the conductive particles 1, the conductive particles 11 or the conductive particles 21 may be used. Moreover, you may use electroconductive particle other than electroconductive particle 1,11,21.

  A connection structure 51 shown in FIG. 1 is a connection that connects a first connection target member 52, a second connection target member 53, and the first connection target member 52 and the second connection target member 53. Part 54. The connection part 54 is formed of the conductive material. The binder resin preferably includes a thermosetting component, and the connection portion 54 is preferably formed by thermosetting the thermosetting component included in the conductive material.

  The first connection target member 52 has a plurality of first electrodes 52a on the surface (upper surface). The second connection target member 53 has a plurality of second electrodes 53a on the surface (lower surface). The first electrode 52 a and the second electrode 53 a are electrically connected by one or a plurality of conductive particles 1. Therefore, the first and second connection target members 52 and 53 are electrically connected by the conductive particles 1.

  FIG. 2 is an enlarged front sectional view of a connection portion between the conductive particle 1 and the first and second electrodes 52a and 53a in the connection structure 51 shown in FIG. As shown in FIG. 2, in the connection structure 51, after the solder layer 3 </ b> B in the conductive particles 1 is melted, the melted solder layer portion 3 </ b> Ba is in sufficient contact with the first and second electrodes 52 a and 53 a. That is, by using the conductive particles 1 whose surface layer is the solder layer 3B, compared to the case where the conductive particles whose surface layer is a metal such as nickel, gold or copper are used, the conductive particles The contact area between 1 and the first and second electrodes 52a and 53a is increased. For this reason, the conduction | electrical_connection reliability and connection reliability of the connection structure 51 can be improved. When flux is used, the flux generally deactivates gradually due to heating. Further, from the viewpoint of further improving the conduction reliability, it is preferable to bring the second conductive layer 3A into contact with the first electrode 52a, and it is preferable to bring the second conductive layer 3A into contact with the second electrode 53a. .

  The said 1st, 2nd connection object member is not specifically limited. Specifically, the first and second connection target members include electronic components such as semiconductor chips, capacitors, and diodes, and circuit boards such as printed boards, flexible printed boards, glass epoxy boards, and glass boards. Examples include parts. The conductive material is preferably a conductive material used for connecting electronic components. The conductive material is preferably a liquid and is a conductive material that is applied to the upper surface of the connection target member in a liquid state.

  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.

(Binder resin)
Thermoplastic compound 1:
In a 3 L separable flask, 219 g of Pripol 1009 (HOOC- (CH ₂ ) ₃₄ —COOH, molecular weight 567, manufactured by Croda Japan Co., Ltd.), 5 g of ethylenediamine (NH ₂ CH ₂ CH ₂ NH ₂ , molecular weight 60), piperazine ( 27 g of C ₄ H ₁₀ N ₂ , molecular weight 86) and 0.8 g of 5% aqueous phosphorous acid solution were added.

  A water separation tube was attached, the temperature was raised to 190 ° C. with stirring under a nitrogen flow, and a polycondensation reaction was performed until the number average molecular weight of the reaction product reached 1400. Thereafter, 83 g of dodecanedioic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at 190 ° C. until the contents became transparent. Thereafter, 358 g of polytetramethylene ether glycol (“PTMG1000” manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1000) and 1 g of Irganox 1098 (manufactured by BASF Japan) were added and stirred until they were even. Thereafter, 0.1 g of antimony trioxide and 0.1 g of monobutylhydroxytin oxide were added, the temperature was raised to 250 ° C., and the mixture was stirred for 30 minutes. The pressure was reduced to 1 mmHg, and the reaction was further performed at 250 ° C. for 4 hours. As a result, a polyamide / polyester block polymer having a number average molecular weight of 28000 and a melting point of 120 ° C. was obtained. This polyamide / polyester block polymer is referred to as thermoplastic compound 1.

Thermosetting compound 1 (epoxy group-containing acrylic resin, "Blemmer CP-30" manufactured by Mitsubishi Chemical Corporation)
Thermosetting compound 2 (Naphthalene type epoxy compound, “HP-4032D” manufactured by DIC)
Thermosetting compound 3 (resorcinol type epoxy compound, “EX-201” manufactured by Nagase ChemteX Corporation)
Thermosetting compound 4 (epoxy compound, “EXA-4850-150” manufactured by DIC)
Thermosetting agent A (imidazole compound, “2P-4MZ” manufactured by Shikoku Kasei Kogyo Co., Ltd.)
Thermal cation generator 1 (compound represented by the following formula (11), compound that releases inorganic acid ion containing phosphorus atom by heating)

  Adhesion imparting agent: “KBE-403” manufactured by Shin-Etsu Chemical Co., Ltd.

(Conductive particles)
Conductive particles 1 (resin core solder coated particles, prepared by the following procedure)
Divinylbenzene resin particles (“Micropearl SP-210” manufactured by Sekisui Chemical Co., Ltd., average particle diameter 10 μm, softening point 330 ° C., 10% K value (23 ° C.) 3.8 GPa) are electroless nickel plated, A base nickel plating layer having a thickness of 0.1 μm was formed on the surface. Next, the resin particles on which the base nickel plating layer was formed were subjected to electrolytic copper plating to form a 1 μm thick copper layer. Further, electrolytic plating was performed using an electrolytic plating solution containing tin and bismuth to form a 2 μm thick solder layer. In this way, a 1 μm thick copper layer is formed on the surface of the resin particles, and a 2 μm thick solder layer (tin: bismuth = 43 wt%: 57 wt%) is formed on the surface of the copper layer. Conductive particles (average particle size 16 μm, CV value 20%, specific gravity 5.3, resin core solder-coated particles) were prepared.

  Further, the following conductive particles 2 and 3 were obtained in the same manner as the conductive particle 1 except that the type of the base particle, the average particle diameter of the base particle, the thickness of the copper layer and the thickness of the solder layer were changed. It was.

Conductive particles 2 (divinylbenzene resin particles, average particle diameter of resin particles 10 μm, resin particles 10% K value (23 ° C.) 3.8 GPa, resin particle softening point 330 ° C., copper layer thickness 3 μm, solder layer 4 μm thickness, average particle size of conductive particles 24 μm, CV value 26%, specific gravity 7.2)
Conductive particles 3 (divinylbenzene resin particles, average particle diameter of resin particles 20 μm, resin particle 10% K value (23 ° C.) 3.6 GPa, resin particle softening point 330 ° C., copper layer thickness 3 μm, solder layer 4 μm thickness, average particle size of conductive particles 34 μm, CV value 25%, specific gravity 5.7)
Conductive particles A: SnBi solder particles (“ST-5” manufactured by Mitsui Kinzoku Co., Ltd., volume average particle size: 5.4 μm, standard deviation: 1.9 μm, CV value 35%, d90: 7.98 μm)
Conductive particles B: SnBi solder particles (“ST-3” manufactured by Mitsui Kinzoku Co., Ltd., volume average particle size 3.4 μm, standard deviation: 1.1 μm, CV value 32%, d90: 5.0 μm)

(Examples 1-14 and Comparative Examples 1-3)
(1) Preparation of anisotropic conductive paste The components shown in Table 1 and Table 2 below were blended in the blending amounts shown in Table 1 and Table 2 to obtain anisotropic conductive paste.

(2) Production of first connection structure (L / S = 50 μm / 50 μm) Upper surface of copper electrode pattern (thermal conductivity of copper 398 W / m · K, copper electrode thickness 10 μm) with L / S of 50 μm / 50 μm A glass epoxy substrate (FR-4 substrate) was prepared. In addition, a flexible printed circuit board having a copper electrode pattern (thermal conductivity of copper 398 W / m · K, copper electrode thickness 10 μm) on the lower surface with a L / S of 50 μm / 50 μm was prepared.

  The overlapping area of the glass epoxy substrate and the flexible substrate was 1.5 cm × 4 mm, and the number of connected electrodes was 75 pairs.

  On the upper surface of the glass epoxy substrate, the anisotropic conductive paste immediately after preparation was applied to a thickness of 50 μm to form an anisotropic conductive material layer. Next, the flexible printed circuit board was laminated on the upper surface of the anisotropic conductive material layer so that the electrodes face each other.

  Thereafter, while adjusting the head temperature so that the temperature of the anisotropic conductive material layer located on the electrode is 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip, and a pressure of 2.0 MPa is applied. After the heating with the melt viscosity of the anisotropic conductive material layer lowered, the heating is followed by heating to 185 ° C. to melt the solder and harden the anisotropic conductive material layer. Got the body.

(3) Production of second connection structure (L / S = 75 μm / 75 μm) Glass epoxy substrate (FR-4 substrate) having a copper electrode pattern (copper electrode thickness 10 μm) having L / S of 75 μm / 75 μm on the upper surface Prepared. Moreover, the flexible printed circuit board which has a copper electrode pattern (copper electrode thickness 10 micrometers) whose L / S is 75 micrometers / 75 micrometers on the lower surface was prepared.

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

(4) Production of third connection structure (L / S = 100 μm / 100 μm) Glass epoxy substrate (FR-4 substrate) having a copper electrode pattern (copper electrode thickness 10 μm) having L / S of 100 μm / 100 μm on the upper surface Prepared. Moreover, the flexible printed circuit board which has a copper electrode pattern (copper electrode thickness 10 micrometers) with L / S of 100 micrometers / 100 micrometers on the lower surface was prepared.

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

(Example 15)
An anisotropic conductive paste was obtained in the same manner as in Example 1 except that the blending amount of the conductive particles was changed from 18 parts by weight to 37 parts by weight. Further, the materials of the glass epoxy substrate electrode and the flexible printed circuit board were changed from copper to silver (thermal conductivity 420 W / m · K) in the same manner as in Example 1 except that the first and second materials were changed. A third connection structure was obtained.

(Example 16)
An anisotropic conductive paste was obtained in the same manner as in Example 1 except that the blending amount of the conductive particles was changed from 18 parts by weight to 37 parts by weight. Further, the materials of the electrode of the glass epoxy board and the electrode of the flexible printed board were changed from copper to gold (thermal conductivity 320 W / m · K), in the same manner as in Example 1, and the first and second A third connection structure was obtained.

(Example 17)
An anisotropic conductive paste was obtained in the same manner as in Example 1 except that the blending amount of the conductive particles was changed from 18 parts by weight to 37 parts by weight. Further, the materials of the glass epoxy substrate electrode and the flexible printed circuit board were changed from copper to aluminum (thermal conductivity 236 W / m · K). A third connection structure was obtained.

(Comparative Example 4)
An anisotropic conductive paste was obtained in the same manner as in Example 1 except that the blending amount of the conductive particles was changed from 18 parts by weight to 37 parts by weight. Further, the materials of the glass epoxy substrate electrode and the flexible printed circuit board were changed from copper to nickel (thermal conductivity 90 W / m · K) in the same manner as in Example 1 except that the first and second materials were changed. A third connection structure was obtained.

(Evaluation)
(1) Thermal conductivity of conductive material The thermal conductivity of the obtained conductive material was measured using a laser flash method thermal constant measuring apparatus ("TC-9000" manufactured by ULVAC-RIKO).

(2) Melt viscosity of conductive material Using rheometer (“STRESSTECH” manufactured by EOLOGICA), measurement conditions: strain control 1 rad, frequency 1 Hz, temperature rising rate 20 ° C./min, measurement temperature range 40-100 ° C. The obtained anisotropic conductive paste was measured for the minimum melt viscosity and the temperature indicating the minimum melt viscosity. Moreover, the melt viscosity in 40 degreeC was obtained. Furthermore, the ratio η * 1 / η * 2 of the viscosity η * 1 at 40 ° C. and the viscosity η * 2 at 100 ° C. was determined.

(3) Disposition accuracy of conductive particles on electrode In the obtained first, second and third connection structures, 100% by weight of the total number of conductive particles contained in the connection portion formed of the conductive material. The ratio (%) of the number of conductive particles arranged on the electrode was evaluated. The arrangement accuracy of the conductive particles on the electrode was determined according to the following criteria.

[Judgment criteria for placement accuracy of conductive particles on electrode]
○○: The ratio of the number of conductive particles arranged on the electrode is 80% or more ○: The ratio of the number of conductive particles arranged on the electrode is 70% or more and less than 80% Δ: On the electrode Ratio of the number of conductive particles arranged is 60% or more and less than 70% ×: Ratio of the number of conductive particles arranged on the electrode is less than 60%

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

[Judgment criteria for conduction reliability]
○: Average value of connection resistance is 10.0Ω or less △: Average value of connection resistance exceeds 10.0Ω, 15.0Ω or less ×: Average value of connection resistance exceeds 15.0Ω

(5) Insulation reliability between adjacent electrodes In the obtained first, second and third connection structures (n = 15), 5 V was applied between the adjacent electrodes, and the resistance value was 25 locations. Measured with Insulation reliability was judged according to the following criteria.

[Criteria for insulation reliability]
○: After 500 hours at 85 ° C. and 85% humidity, the insulation resistance is 100 MΩ or more. Δ: After 500 hours at 85 ° C. and 85% humidity, the insulation resistance is 10 MΩ or more, 100 MΩ or less. After 500 hours, the insulation resistance is less than 10MΩ

(6) Presence / absence of voids In the obtained first, second, and third connection structures, it was observed with an optical microscope whether or not voids were generated in the connection portions formed of the conductive material. The presence or absence of voids was determined according to the following criteria. If there are no voids, the connection reliability increases, and the fewer the voids, the higher the connection reliability.

[Criteria for the presence or absence of voids]
○: No void △: There is a slight void, but there is no void larger than the electrode L / S, pitch ×: There is a void larger than the size between adjacent electrodes

  The results are shown in Tables 1 and 2 below.

  In all examples using conductive particles having a copper layer and a solder layer, the copper layer was in contact with the electrodes in the obtained first, second and third connection structures. In addition, when the conductive particles 1 to 3 are used, the distance between the electrodes is regulated with high accuracy by the resin particles as compared with the case where the conductive particles A and B are used, and the distance between the electrodes varies. It was small.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Base material particle 3 ... Conductive layer 3A ... 2nd conductive layer 3B ... Solder layer 3Ba ... Molten solder layer part 11 ... Conductive particle 12 ... Solder layer 21 ... Conductive particle 51 ... Connection structure Body 52 ... first connection target member 52a ... first electrode 53 ... second connection target member 53a ... second electrode 54 ... connection portion

Claims (9)

A conductive material used for electrical connection of an electrode having an outer surface formed of a material having a thermal conductivity of 200 W / m · K or more,
Including conductive particles having solder on a conductive surface, and a binder resin;
The thermal conductivity is 0.3 W / m · K or less,
The electrically conductive material whose minimum melt viscosity in 40-100 degreeC is 70 Pa.s or less.   The conductive material according to claim 1, wherein a particle diameter of the conductive particles is 0.5 μm or more and 30 μm or less.   The conductive material according to claim 1, wherein the conductive particles are solder particles. A conductive material used for electrical connection of an electrode having an outer surface formed of a material having a thermal conductivity of 300 W / m · K or more,
4. The conductive material according to claim 1, wherein the material having a thermal conductivity of 300 W / m · K or more is gold, silver, or copper.   The conductive material according to claim 1, wherein the conductive particles include base particles and a solder layer disposed on a surface of the base particles. A first connection object member having a first electrode on its surface;
A second connection target member having a second electrode on its surface;
A connection portion connecting the first connection target member and the second connection target member;
The connection portion is formed of the conductive material according to any one of claims 1 to 5,
At least one of the first electrode and the second electrode has an outer surface made of a material having a thermal conductivity of 200 W / m · K or more,
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles. At least one of the first electrode and the second electrode has an outer surface made of a material having a thermal conductivity of 300 W / m · K,
The connection structure according to claim 6, wherein the material having a thermal conductivity of 300 W / m · K or more is gold, silver, or copper. Disposing the conductive material according to any one of claims 1 to 5 on a first connection target member having a first electrode on a surface;
Disposing a second connection target member having a second electrode on the surface of the conductive material opposite to the first connection target member side; and
Heating the conductive material to 120 to 220 ° C., connecting the first connection target member and the second connection target member with the conductive material, and forming a connection portion,
From the step of arranging the conductive particles to before the step of forming the connection portion, further comprising the step of heating the conductive material to a temperature at which the melt viscosity is 70 Pa · s or less,
At least one of the first electrode and the second electrode has an outer surface made of a material having a thermal conductivity of 200 W / m · K or more,
A method for manufacturing a connection structure, wherein a connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles is obtained. At least one of the first electrode and the second electrode has an outer surface made of a material having a thermal conductivity of 300 W / m · K or more,
The manufacturing method of the connection structure of Claim 8 whose material whose said heat conductivity is 300 W / m * K is gold, silver, or copper.

Images