JP6333624B2 - Connection structure - Google Patents

Description

  The present invention relates to a connection structure in which electrodes are electrically connected by conductive particles.

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

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

  For example, when 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 connection structure, Patent Document 1 below discloses a connection structure having an electric member connection structure. Here, two electric members having conductors protruding from the surface of the electric insulator are opposed so that the portions to be electrically connected of the conductors face each other, and the electric conductors are electrically connected. Conductive particles that are deformed between power parts and bite into the conductor are disposed between the conductors, and a part of the part to be electrically connected to the conductor is brought into contact with the conductive particles to It is fixed with an insulating adhesive. The height of at least one of the conductors is set larger than the diameter of the conductive particles.

JP 2003-68794 A

  As described in Patent Document 1, the connection resistance between the electrodes may not be sufficiently lowered only by causing the conductive particles to bite into the conductor (electrode).

  The objective of this invention is providing the connection structure which can make low the connection resistance between electrodes.

  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 connection portion connecting the second connection target member, and the connection portion is formed of a conductive material including a conductive particle having a plurality of protrusions on a conductive surface and a binder resin. The first electrode and the second electrode are electrically connected by the conductive particles, and the metal Vickers on the surface of the first electrode in a portion in contact with the conductive particles The hardness is greater than the Vickers hardness of the metal on the surface of the second electrode at the portion in contact with the conductive particles, and the connection direction of the first electrode, the conductive particles, and the second electrode In the cross section, the protrusion in the conductive particle Portion and the connection distance between the first electrode 0.3μm or more and less 4.0 .mu.m, the connection structure is provided.

  In a specific aspect of the connection structure according to the present invention, in the cross section in the connection direction of the first electrode, the conductive particle, and the second electrode of the connection structure, the conductive particle and the first The connection distance with one electrode is 0.5 μm or more and 5.0 μm or less.

  On the specific situation with the connection structure which concerns on this invention, the said electroconductive particle has a base material particle and the electroconductive part arrange | positioned on the surface of the said base material particle.

  On the specific situation with the connection structure which concerns on this invention, the said base material particle is a core-shell particle which has an organic core and the inorganic shell arrange | positioned on the surface of the said organic core.

  On the specific situation with the connection structure which concerns on this invention, the particle diameter of the said base material particle contained in the said electrically-conductive material is 1 micrometer or more and 5 micrometers or less.

  In a specific aspect of the connection structure according to the present invention, in the cross section in the connection direction of the first electrode, the conductive particle, and the second electrode of the connection structure, the protrusion in the conductive particle The connection distance between the portion and the second electrode is 0.3 μm or more and 4.0 μm or less.

  In a specific aspect of the connection structure according to the present invention, in the cross section in the connection direction of the first electrode, the conductive particle, and the second electrode of the connection structure, the conductive particle and the first The connection distance to the second electrode is 0.5 μm or more and 5.0 μm or less.

  In a specific aspect of the connection structure according to the present invention, the conductivity in contact with the first electrode in a cross-section in the connection direction of the first electrode, the conductive particles, and the second electrode. The number of the protrusions of the particle is 2 or more and 50 or less.

  The connection structure according to the present invention includes 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 above A connecting portion that connects the second connection target member, and the connecting portion is formed of a conductive material including a conductive particle having a plurality of protrusions on a conductive surface and a binder resin. The first electrode and the second electrode are electrically connected by the conductive particles, and the metal Vickers on the surface of the first electrode in a portion in contact with the conductive particles The hardness is larger than the Vickers hardness of the metal on the surface of the second electrode at the portion in contact with the conductive particles, and the connection direction of the first electrode, the conductive particles, and the second electrode In the cross section of the conductive particle, the protrusion Portion and the connection distance between the first electrode 0.3μm or more, because it is less 4.0 .mu.m, it is possible to lower the connection resistance between the first and second electrodes.

FIG. 1 is a cross-sectional view schematically showing a connection structure according to the first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a connection portion between the electrodes shown in FIG. FIG. 3 is a cross-sectional view schematically showing conductive particles used in the connection structure according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view schematically showing a first modification of the conductive particles. FIG. 5 is a cross-sectional view for explaining the connection distance between the protruding portion of the conductive particles and the first and second electrodes in the cross section in the connection direction of the first electrode, the conductive particles, and the second electrode. It is. FIG. 6 is a cross-sectional view for explaining the connection distance between the conductive particles and the first and second electrodes in the cross section in the connection direction of the first electrode, the conductive particles, and the second electrode. FIG. 7 is an example of a cross-sectional image in the connection direction of the first electrode, the conductive particles, and the second electrode in the connection structure according to the embodiment of the present invention. FIG. 8 is an example of a cross-sectional image in the connection direction of the first electrode, the conductive particles, and the second electrode in the connection structure not included in the present invention.

  Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings. In the referenced drawings, the size, thickness, and dimensions are appropriately changed from the actual size, thickness, and dimensions for convenience of illustration.

  FIG. 1 is a cross-sectional view schematically showing a connection structure according to the first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a connection portion between the electrodes shown in FIG.

  The connection structure 1 shown in FIG. 1 includes a first connection target member 2 having a first electrode 2a on the surface, a second connection target member 3 having a second electrode 3a on the surface, and a first connection. A connecting portion 4 that connects the target member 2 and the second connection target member 3 is provided. The connection part 4 is formed of a conductive material including the conductive particles 11 and the binder resin 15. The first electrode 2 a and the second electrode 3 a are electrically connected by the conductive particles 11.

  The Vickers hardness of the metal on the surface of the first electrode 2a in the portion in contact with the conductive particles 11 is larger than the Vickers hardness of the metal on the surface of the second electrode 3a in the portion in contact with the conductive particles 11. large.

  FIG. 5 shows the connection between the projection 11a portion of the conductive particle 11 and the first and second electrodes 2a and 3a in the cross section in the connection direction of the first electrode 2a, the conductive particle 11 and the second electrode 3a. It is sectional drawing for demonstrating distance. FIG. 5 corresponds to FIG.

  As shown in FIG. 5, in this embodiment, in the cross section in the connecting direction of the first electrode 2a, the conductive particle 11, and the second electrode 3a, the protrusion 11a portion of the conductive particle 11 and the first electrode 2a. The connection distance x1 (the total length of the thick line X1 shown in FIG. 5) is 0.3 μm or more and 4.0 μm or less. The connection distance x1 between the protrusion 11a portion of the conductive particle 11 and the first electrode 2a does not include the connection distance between the portion of the conductive particle 11 where the protrusion 11a does not exist and the first electrode 2a. From the viewpoint of further reducing the connection resistance and further suppressing the increase in connection resistance under high temperature and high humidity, the connection distance x1 is preferably 3.5 μm or less.

  When the plurality of protrusions are connected to the first electrode, the connection distance x1 between the protrusions and the first electrode in the conductive particles is the total connection between the plurality of protrusions and the first electrode. This means the distance (the total length of the two thick lines X1 shown in FIG. 5).

  FIG. 7 shows an example of a cross-sectional image in the connection direction of the first electrode, the conductive particles, and the second electrode in the connection structure according to the embodiment of the present invention. FIG. 8 shows an example of a cross-sectional image in the connection direction of the first electrode, the conductive particles, and the second electrode in the connection structure not included in the present invention.

  In the connection structure 1, it is possible to reduce the connection resistance and further suppress an increase in the connection resistance under high temperature and high humidity.

  FIG. 3 is a cross-sectional view schematically showing conductive particles used in the connection structure according to the first embodiment of the present invention.

  The conductive particle 11 shown in FIG. 3 includes a base particle 12, a conductive part 13, and a core substance 14. The conductive part 13 is a conductive layer.

  The conductive portion 13 is disposed on the surface of the base particle 12. The conductive particles 11 are coated particles in which the surface of the base particle 12 is coated with the conductive portion 13.

  The conductive particles 11 have protrusions 11a on the conductive surface. There are a plurality of protrusions 11a. The conductive portion 13 has a plurality of protrusions 13a on the outer surface. A plurality of core substances 14 are arranged on the surface of the base particle 12. The plurality of core materials 14 are embedded in the conductive portion 13. The core substance 14 is disposed inside the protrusions 11a and 13a. The conductive portion 13 covers a plurality of core materials 14. The outer surface of the conductive portion 13 is raised by the plurality of core materials 14, and protrusions 11 a and 13 a are formed.

  FIG. 4 is a cross-sectional view showing a first modification of the conductive particles.

  The conductive particle 21 shown in FIG. 4 includes the base material particle 12, the first conductive part 22, the second conductive part 23, the core substance 14, and the insulating substance 24. Each of the first and second conductive portions 22 and 23 is a conductive layer.

  The conductive particles 21 have protrusions 21a on the conductive surface. The first conductive portion 22 is disposed on the surface of the base particle 12. The first conductive portion 22 has no protrusion on the outer surface. The second conductive portion 23 is disposed on the outer surface of the first conductive portion 22. The second conductive portion 23 has a protrusion 23a on the outer surface. A first conductive portion 22 is disposed between the base particle 12 and the second conductive portion 23. The conductive particle 21 is a coated particle in which the surface of the base particle 12 is covered with the first conductive portion 22 and the second conductive portion 23.

  Like the conductive particles 11 and 21, the conductive portion may have a single layer structure or a multilayer structure.

  The conductive particles 21 have a plurality of core substances 14 on the outer surface of the first conductive portion 22. The second conductive portion 23 covers the base particle 12 and the core substance 14. By covering the core material 14 with the second conductive portion 23, the conductive particles 21 have a plurality of protrusions 21a on the conductive surface, and the second conductive portion 23 has a plurality of protrusions on the outer surface. 23a. The surface of the second conductive portion 23 is raised by the core substance 14, and a plurality of protrusions 21a and 23a are formed.

  Like the conductive particles 11 and 21, the core substance may be disposed on the surface of the base particle, or may be disposed on the surface of the first conductive portion, and is in contact with the base particle. Or may not be in contact with the base particles.

  In addition, the conductive particles 21 include a plurality of insulating substances 24 disposed on the outer surface of the second conductive portion 23 (conductive portion).

  Like the electroconductive particle 11 and 21, the electroconductive particle may be provided with the insulating substance arrange | positioned on the outer surface of an electroconductive part, and does not need to be provided.

  From the viewpoint of further reducing the connection resistance between the electrodes, the conductive particles may have protrusions on the conductive surface. The conductive particles may have protrusions on the outer surface of the conductive part.

  From the viewpoint of further lowering the connection resistance between the electrodes, the Vickers hardness of the metal on the surface of the first electrode in contact with the conductive particles is preferably 10 Hv or higher, more preferably 20 Hv or higher, preferably Is 500 Hv or less, more preferably 450 Hv or less. From the viewpoint of further reducing the connection resistance between the electrodes, the Vickers hardness of the metal on the surface of the first electrode in the portion in contact with the conductive particles and the portion in contact with the conductive particles The absolute value of the difference from the Vickers hardness of the metal on the surface of the second electrode is preferably 10 Hv or more, more preferably 20 Hv or more, preferably 450 Hv or less, more preferably 400 Hv or less.

  As shown in FIG. 2, it is preferable that a part of electroconductive particle is embedded in the 2nd electrode. From the viewpoint of further reducing the connection resistance between the electrodes, the maximum value Dm of the conductive particles embedded in the second electrode (see FIG. 2) is preferably 1 nm or more, preferably 1000 nm or less. is there.

  In the present invention, the conductive particles may not be embedded in the second electrode. In the present invention, the conductive particles are not embedded in the second electrode, or a part of the conductive particles are embedded in the second electrode, and the second of the conductive particles is The maximum depth Dm embedded in the electrode is preferably 1000 nm or less. The maximum depth Dm embedded in the second electrode of the conductive particles may be 1 nm or more, 10 nm or more, preferably 700 nm or less, more preferably 400 nm or less. is there. By connecting the conductive particles shallowly in the second electrode, it is possible to further improve the connection reliability against the impact of the connection structure while maintaining the connection resistance between the electrodes even lower.

  As shown in FIG. 2, the maximum value Dm of the depth is obtained by embedding the conductive particles from the reference surface with the surface of the second electrode in a portion where the conductive particles are not in contact as a reference surface. Indicates the maximum distance of the part that is The maximum value Dm of the depth generally corresponds to the maximum value of the depth of the recess formed by embedding the conductive particles in the second electrode.

The compression elastic modulus (5% K value) when the conductive particles contained in the conductive material are compressed by 5% is preferably 1000 N / mm ² or more, more preferably 3000 N / mm ² or more, preferably 20000 N / mm ^2. Hereinafter, it is more preferably 18000 N / mm ² or less. In order to better control the structure in which the conductive particles are embedded and to further reduce the connection resistance between the electrodes, the 5% K value of the conductive particles is preferably not less than the above lower limit and not more than the above upper limit.

  The compression elastic modulus (5% K value) of the conductive particles can be measured as follows.

  Using a micro-compression tester, the conductive particles are compressed under the conditions of 25 ° C., compression speed of 0.3 mN / sec, and maximum test load of 20 mN on the end face of a cylindrical indenter (diameter: 100 μm, made of diamond). 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.

10% K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value when the conductive particles are 10% compressively deformed (N)
S: Compression displacement (mm) when the conductive particles are 10% 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 improving the connection state and further lowering the connection resistance between the electrodes, the conductive particles have base particles and conductive portions arranged on the surfaces of the base particles. Is preferred.

  From the viewpoint of further improving the connection state and further reducing the connection resistance between the electrodes, the base particle is a core-shell particle having an organic core and an inorganic shell disposed on the surface of the organic core. Preferably there is.

  From the viewpoint of further improving the connection state and further reducing the connection resistance between the electrodes, the particle diameter of the base material particles contained in the conductive material is preferably 1 μm or more, and preferably 5 μm or less.

  From the viewpoint of further improving the connection state and further reducing the connection resistance between the electrodes, a cross-section in the connection direction of the first electrode, the conductive particles, and the second electrode of the connection structure ( For example, in the cross section in FIG. 5, the connection distance x2 (total length of the thick line X2 in FIG. 5) between the protruding portion of the conductive particles and the second electrode is preferably 0.3 μm or more, more preferably. Is 1.0 μm or more, preferably 4.0 μm or less, more preferably 3.5 μm or less. When the connection distance x2 is not less than the above lower limit and not more than the above upper limit, the connection resistance can be further reduced, and the increase in connection resistance under high temperature and high humidity can be further suppressed.

  From the viewpoint of further improving the connection state and further reducing the connection resistance between the electrodes, a cross-section in the connection direction of the first electrode, the conductive particles, and the second electrode of the connection structure ( For example, in the cross section in FIG. 6, the connection distance y1 between the conductive particles and the first electrode (the length of the thick line Y1 in FIG. 6) is preferably 0.5 μm or more, more preferably 1.0 μm or more. Preferably it is 5.0 micrometers or less, More preferably, it is 4.5 micrometers or less.

  From the viewpoint of further improving the connection state and further reducing the connection resistance between the electrodes, a cross-section in the connection direction of the first electrode, the conductive particles, and the second electrode of the connection structure ( For example, in the cross section in FIG. 6, the connection distance y2 between the conductive particles and the second electrode (the length of the thick line Y2 in FIG. 6) is preferably 0.5 μm or more, more preferably 1.0 μm or more, Preferably it is 5.0 micrometers or less, More preferably, it is 4.5 micrometers or less.

  From the viewpoint of further improving the connection state and further reducing the connection resistance between the electrodes, the first electrode, the conductive particles, and the second electrode in the cross-section in the connecting direction, the first electrode The number of the protrusions of the conductive particles in contact with the electrode is preferably 2 or more, and preferably 50 or less.

  Hereinafter, the detail of the electroconductive particle used for the said connection structure is demonstrated.

[Base material particles]
Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particles may be core-shell particles.

  The substrate particles are more preferably resin particles or organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles. By using these preferable base particles, conductive particles more suitable for electrical connection between the electrodes can be obtained.

  When connecting between electrodes using the said electroconductive particle, after arrange | positioning the said electroconductive particle between electrodes, the said electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles or organic-inorganic hybrid 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 connection resistance between electrodes becomes still lower.

  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, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, polyether ether Tons, polyethersulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. Resin for forming the resin particles can be designed and synthesized, and the hardness of the base particles can be easily controlled within a suitable range, which is suitable for conductive materials and having physical properties at the time of compression. Is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups.

  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 glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure And silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane It is done.

  The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

  In the case where the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal particles, examples of the inorganic material for forming the substrate particles include silica, alumina, barium titanate, zirconia, and carbon black. . This inorganic substance is preferably not a metal. The particles formed by the silica are not particularly limited. For example, after forming a crosslinked polymer particle by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups, firing may be performed as necessary. 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.

  The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. From the viewpoint of effectively reducing the connection resistance between the electrodes, the base material particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

  Examples of the material for forming the organic core include the resin for forming the resin particles described above.

  Examples of the material for forming the inorganic shell include inorganic substances for forming the above-described base material particles. The material for forming the inorganic shell is preferably silica. The inorganic shell is preferably formed on the surface of the core by forming a metal alkoxide into a shell by a sol-gel method and then sintering the shell. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed of a silane alkoxide.

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

  The particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, further preferably 1 μm or more, particularly preferably 2 μm or more, preferably 5 μm or less, more preferably 3 μm or less. When the particle diameter of the substrate particles is not less than the above lower limit and not more than the above upper limit, even when the distance between the electrodes is small and the thickness of the conductive portion is increased, small conductive particles can be obtained.

  The particle diameter of the base particle indicates a diameter when the base particle is a true sphere, and indicates a maximum diameter when the base particle is not a true sphere.

[Conductive part]
The metal that is the material of the conductive part is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and tungsten. , Molybdenum, and alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. Especially, since the connection resistance between electrodes can be made still lower, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is more preferable.

  The conductive part may be formed of one layer. It may be formed of a plurality of layers. That is, the conductive part may have a laminated structure of two or more layers. When the conductive portion is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver, and is a gold layer. Is more preferable. When the outermost layer is these preferable conductive portions, the connection resistance between the electrodes is further reduced. Moreover, when the outermost layer is a gold layer, the corrosion resistance is further enhanced.

  The method for forming the conductive portion on the surface of the particle is not particularly limited. Examples of the method for forming the conductive part include a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating the surface of particles with metal powder or a paste containing metal powder and a binder. Can be mentioned. Especially, since formation of an electroconductive part is simple, the method by electroless plating is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering.

  The thickness of the conductive part (when the conductive part is a multilayer, the total thickness of the conductive part) 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, Preferably it is 0.3 micrometer or less. When the thickness of the conductive part is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained, and the conductive particles are not too hard, and the conductive particles are sufficiently deformed when connecting the electrodes. .

  When the conductive part is formed of a plurality of layers, the thickness of the conductive part of the outermost layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably 0. .1 μm or less. When the thickness of the conductive portion of the outermost layer is not less than the above lower limit and not more than the above upper limit, the coating by the conductive portion of the outermost layer becomes uniform, corrosion resistance is sufficiently high, and the connection resistance between the electrodes is further increased. Lower. Further, the thinner the gold layer when the outermost layer is a gold layer, the lower the cost.

  The thickness of the conductive portion can be measured by observing the cross section of the conductive particles using, for example, a transmission electron microscope (TEM).

  The conductive particles preferably have protrusions on the conductive surface, and preferably have protrusions on the outer surface of the conductive part. It is preferable that there are a plurality of the protrusions. An oxide film is often formed on the surface of the conductive part and the surface of the electrode connected by the conductive particles. When conductive particles having protrusions are used, the oxide film is effectively eliminated by the protrusions by placing the conductive particles between the electrodes and pressing them. For this reason, an electrode and the electroconductive part of electroconductive particle can be made to contact still more reliably, and the connection resistance between electrodes can be made low. Further, when the conductive particles have an insulating material on the surface, the insulating material between the conductive particles and the electrode can be eliminated by the protrusions of the conductive particles. Further, the binder resin can be effectively eliminated by the protrusions of the conductive particles. For this reason, the conduction | electrical_connection reliability between electrodes can be improved.

  As a method of forming protrusions on the surface of the conductive particle, a method of forming a conductive part by electroless plating after attaching a core substance to the surface of the particle, and forming a conductive part by electroless plating on the surface of the particle After that, there are a method of attaching a core substance and further forming a conductive part by electroless plating, a method of adding a core substance in the middle of forming a conductive part by electroless plating, and the like. In addition, the core material may not be used to form the protrusion.

  Examples of the material of the core substance include a conductive substance and a non-conductive substance. Examples of the conductive material include conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the non-conductive substance include silica, alumina, barium titanate, zirconia, and the like. Among them, metal is preferable because conductivity can be increased and connection resistance can be effectively reduced. The core substance is preferably metal particles.

  Examples of the metal that is a material of the core substance include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, tungsten, Examples thereof include metals such as molybdenum and cadmium, and alloys composed of two or more metals such as tin-lead alloy, tin-copper alloy, tin-silver alloy, tin-lead-silver alloy, and tungsten carbide. Of these, nickel, copper, silver or gold is preferable. The metal that is the material of the core substance may be the same as or different from the metal for forming the conductive part. The metal for forming the core substance preferably includes a metal for forming the conductive part. The metal for forming the core substance preferably contains nickel. The metal for forming the core substance preferably contains nickel.

  The shape of the core material is not particularly limited. The shape of the core substance is preferably a lump. Examples of the core substance include a particulate lump, an agglomerate in which a plurality of fine particles are aggregated, and an irregular lump.

  The average diameter (average particle diameter) of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average diameter of the core substance is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes is effectively reduced.

  The “average diameter (average particle diameter)” of the core substance indicates a number average diameter (number average particle diameter). The average diameter of the core material is obtained by observing 50 arbitrary core materials with an electron microscope or an optical microscope and calculating an average value.

  The conductive particles may include an insulating material disposed on the outer surface of the conductive part. In this case, when the conductive particles are used for connection between the electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact with each other, an insulating material is present between the plurality of electrodes, so that it is possible to prevent a short circuit between electrodes adjacent in the lateral direction instead of between the upper and lower electrodes. In addition, when connecting the electrodes, the insulating particles between the conductive portions of the conductive particles and the electrodes can be easily removed by pressurizing the conductive particles with the two electrodes. When the conductive particles have protrusions on the conductive surface, the insulating material between the conductive portion of the conductive particles and the electrode can be more easily removed. The insulating material is preferably an insulating layer or insulating particles, and more preferably insulating particles. The insulating particles are preferably insulating resin particles.

(Conductive material)
The conductive material includes conductive particles and a binder resin. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

  The binder resin is not particularly limited. As the binder resin, a known 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.

  Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. Examples of the curable resin include an epoxy resin, a urethane resin, a polyimide resin, and an unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated product of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogenated product of a styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

  In addition to the conductive particles and the binder resin, the 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, and a light stabilizer. Various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant may be contained.

  The conductive material can be used as a conductive paste and a conductive film. When the conductive material 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.

  In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably 99.% or more. It is 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, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target member connected by the conductive material is further increased.

  In 100% by weight of the 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 40% by weight or less, more preferably 20% by weight or less, More preferably, it is 10 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, the conduction reliability between the electrodes is further enhanced.

(Other details of connection structure)
The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of 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. Methods and the like. 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.

  Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors, and diodes, and electronic components such as printed boards, flexible printed boards, glass epoxy boards, and glass boards. The connection target member is preferably an electronic component.

  Examples of the electrode provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a silver electrode, a molybdenum electrode, and a tungsten electrode. When the connection object member is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient and the electrode by which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the material for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

  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) Preparation of conductive particles The surface of divinylbenzene copolymer resin particles having a particle diameter of 3.0 [mu] m ("Micropearl SP-203" manufactured by Sekisui Chemical Co., Ltd.) is inorganicized using a condensation reaction by a sol-gel reaction. Core-shell type organic-inorganic hybrid particles (base material particles) coated with a shell (thickness 250 nm) were prepared.

  The obtained organic-inorganic hybrid particles were etched and washed with water. Next, organic-inorganic hybrid particles were added to 100 mL of a palladium-catalyzed solution containing 8% by weight of a palladium catalyst and stirred. Then, it filtered and wash | cleaned. Organic / inorganic hybrid particles were added to 0.5 wt% dimethylamine borane solution at pH 6 to obtain organic / inorganic hybrid particles to which palladium was attached.

  The organic-inorganic hybrid particles to which palladium was attached were stirred and dispersed in 300 mL of ion exchange water for 3 minutes to obtain a dispersion. Next, 1 g of metallic nickel particle slurry (average particle diameter 100 nm) was added to the dispersion over 3 minutes to obtain organic-inorganic hybrid particles to which a core substance was adhered. The organic-inorganic hybrid particles to which the core material was adhered were added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

  Further, a nickel plating solution (pH 8.5) containing 0.23 mol / L of nickel sulfate, 0.92 mol / L of dimethylamine borane and 0.5 mol / L of sodium citrate was prepared.

  While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. Thereafter, the suspension is filtered to take out the particles, washed with water, and dried to provide a nickel-boron conductive layer (thickness 100 nm, boron content 0.5 wt%) on the surface of the organic-inorganic hybrid particles. Arranged to obtain conductive particles.

(2) Production of conductive material 7 parts by weight of the obtained conductive particles, 25 parts by weight of bisphenol A type phenoxy resin, 4 parts by weight of fluorene type epoxy resin, 30 parts by weight of phenol novolac type epoxy resin, SI-60L An anisotropic conductive paste was obtained by blending (manufactured by Sanshin Chemical Industry Co., Ltd.) and defoaming and stirring for 3 minutes.

(2) Production of Conductive Material The obtained conductive particles are added to “Struct Bond XN-5A” manufactured by Mitsui Chemicals so that the content is 10% by weight, and dispersed to obtain an anisotropic conductive paste. It was.

(3) Production of Connection Structure A transparent glass substrate having an IZO electrode pattern (first electrode, metal Vickers hardness of 100 Hv on the electrode surface) having an L / S of 10 μm / 20 μm was prepared. Further, a semiconductor chip was prepared in which an Au electrode pattern (second electrode, metal Vickers hardness of 50 Hv on the electrode surface) having L / S of 10 μm / 20 μm was formed on the lower surface.

  On the transparent glass substrate, the obtained anisotropic conductive paste was applied to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip and a pressure of 1 MPa is applied to form the anisotropic conductive paste layer. Completely cured at 185 ° C. to obtain a connection structure.

(Example 2)
A connection structure was obtained in the same manner as in Example 1 except that the boron content in the nickel-boron conductive layer was changed from 0.5 wt% to 3 wt%.

(Example 3)
The connection structure was the same as in Example 1, except that the metal nickel particle slurry (average particle diameter 100 nm) was used and the protrusion was formed by adjusting the amount of precipitation partially when the conductive layer was formed. Got the body.

Example 4
A connection structure was obtained in the same manner as in Example 1 except that the metal nickel particle slurry was changed to alumina slurry (average particle diameter 100 nm).

(Example 5)
Prepared core-shell type organic-inorganic hybrid particles (base material particles) with the surface of divinylbenzene copolymer resin particles having a particle size of 1.5 μm coated with an inorganic shell (thickness 250 nm) using a condensation reaction by sol-gel reaction did. A connection structure was obtained in the same manner as in Example 1 except that the organic-inorganic hybrid particles were used.

(Example 6)
Prepared core-shell type organic-inorganic hybrid particles (base material particles), in which the surface of divinylbenzene copolymer resin particles with a particle size of 4.5 μm is coated with an inorganic shell (thickness 250 nm) using a condensation reaction by sol-gel reaction did. A connection structure was obtained in the same manner as in Example 1 except that the organic-inorganic hybrid particles were used.

(Example 7)
A connection structure was obtained in the same manner as in Example 1 except that the thickness of the inorganic shell was changed to 350 nm.

(Example 8)
A connection structure was obtained in the same manner as in Example 1 except that the thickness of the inorganic shell was changed to 100 nm.

Example 9
A connection structure was obtained in the same manner as in Example 1 except that the thickness of the inorganic shell was changed to 500 nm.

(Example 10)
A connection structure was obtained in the same manner as in Example 1 except that the thickness of the inorganic shell was changed to 75 nm.

(Example 11)
A connection structure was obtained in the same manner as in Example 1 except that the thickness of the inorganic shell was changed to 750 nm.

(Example 12)
A connection structure was obtained in the same manner as in Example 1 except that the thickness of the inorganic shell was changed to 1000 nm.

(Example 13)
To a 1000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, condenser and temperature probe, 100 mmol of methyl methacrylate and N, N, N-trimethyl-N-2-methacryloyloxyethyl A monomer composition containing 1 mmol of ammonium chloride and 1 mmol of 2,2′-azobis (2-amidinopropane) dihydrochloride was weighed in ion-exchanged water so that the solid content was 5% by weight, and then at 200 rpm. The mixture was stirred and polymerized at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion of the reaction, it was freeze-dried to obtain insulating particles having an ammonium group on the surface, an average particle size of 220 nm, and a CV value of 10%.

  The insulating particles were dispersed in ion exchange water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of insulating particles.

  10 g of the conductive particles obtained in Example 1 were dispersed in 500 mL of ion exchange water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtration through a 3 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles having insulating particles attached thereto.

  When observed with a scanning electron microscope (SEM), only one coating layer of insulating particles was formed on the surface of the conductive particles. The coverage of the insulating particles with respect to the area of 2.5 μm from the center of the conductive particles by image analysis (that is, the projected area of the particle diameter of the insulating particles) was calculated to be 30%.

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

(Example 14)
A connection structure was obtained in the same manner as in Example 1 except that the IZO electrode pattern as the first electrode was changed to an Al—Ti electrode pattern (metal Vickers hardness 200 Hv on the electrode surface).

(Comparative Example 1)
Example except that organic / inorganic hybrid particles before adhering the core substance were changed to divinylbenzene copolymer resin particles having a particle size of 3.5 μm (“Micropearl SP-2035” manufactured by Sekisui Chemical Co., Ltd.) In the same manner as in No. 1, a connection structure was obtained.

(Example 15)
A connection structure was obtained in the same manner as in Example 1 except that the thickness of the inorganic shell was changed to 30 nm.

(Comparative Example 2)
Example 1 except that the resin particles used for the organic / inorganic hybrid particles were changed to divinylbenzene copolymer resin particles (“Micropearl SP-2055” manufactured by Sekisui Chemical Co., Ltd.) having a particle size of 5.5 μm. Thus, a connection structure was obtained.

(Evaluation)
(1) Compressive elastic modulus of conductive particles (5% K value)
The 5% K value of the conductive particles was measured using a micro-compression tester (Fischer Scope H-100, manufactured by Fischer) under the condition described above at 23 ° C.

(2) Connection State The obtained connection structure was cut to expose the cross section of the conductive particles in the connection direction of the first electrode, the conductive particles, and the second electrode. The exposed portion includes the center of the conductive particles. The following evaluation was performed.

  2-1) In the cross section, the connection distance x1 between the protruding portion of the conductive particles and the first electrode was evaluated.

  2-2) In the cross section, the connection distance x2 between the protruding portion of the conductive particle and the second electrode was evaluated.

  2-3) In the cross section, it was evaluated whether a part of the conductive particles was embedded in the second electrode.

  2-4) In the cross section, the maximum value Dm of the depth embedded in the second electrode of the conductive particles was evaluated. In the cross section, a portion showing the maximum depth of the conductive particles embedded in the second electrode appeared.

  2-5) In the cross section, the connection distance y1 between the conductive particles and the first electrode was evaluated.

  2-6) In the cross section, the connection distance y2 between the conductive particles and the second electrode was evaluated.

  2-7) In the cross section, the number of the protrusions of the conductive particles in contact with the first electrode was evaluated.

(3) Connection resistance 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 the two 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. From the connection resistance, the conduction reliability was judged according to the following criteria.

[Criteria for connection resistance]
○○○: Connection resistance is 2.0Ω or less ○○: Connection resistance is over 2.0Ω, 3.0Ω or less ○: Connection resistance is over 3.0Ω, 5.0Ω or less Δ: Connection resistance is 5.0Ω Exceeding 10Ω ×: Connection resistance exceeds 10Ω

(4) Resistance after reliability test The obtained connection structure was left in an environment of 85 ° C. and humidity of 85% for 500 hours. After leaving, the connection resistance between the opposing electrodes was measured by the 4-terminal method. Further, the resistance after the reliability test was determined according to the following criteria.

[Criteria for resistance after reliability test]
○○○: Connection resistance is 2.5Ω or less ○○: Connection resistance is over 2.5Ω, 3.0Ω or less ○: Connection resistance is over 3.0Ω, 5.0Ω or less Δ: Connection resistance is 5.0Ω Exceeds 10.0Ω or less ×: Connection resistance exceeds 10.0Ω

  The results are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 1 ... Connection structure 2 ... 1st connection object member 2a ... 1st electrode 3 ... 2nd connection object member 3a ... 2nd electrode 4 ... Connection part 11 ... Conductive particle | grains 11a ... Protrusion 12 ... Base particle 13: Conductive part (conductive layer)
13a ... Projection 14 ... Core material 15 ... Binder resin 21 ... Conductive particles 21a ... Projection 22 ... First conductive part (first conductive layer)
23: Second conductive portion (second conductive layer)
23a ... Protrusions 24 ... Insulating material

Claims (8)

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 connecting portion is formed of a conductive material including a conductive particle having a plurality of protrusions on a conductive surface and a binder resin,
The first electrode and the second electrode are electrically connected by the conductive particles;
The Vickers hardness of the metal on the surface of the first electrode in the portion in contact with the conductive particles is greater than the Vickers hardness of the metal on the surface of the second electrode in the portion in contact with the conductive particles. big,
The Vickers hardness of the metal on the surface of the first electrode in the portion in contact with the conductive particles and the Vickers hardness of the metal on the surface of the second electrode in the portion in contact with the conductive particles The absolute value of the difference is 10 Hv or more and 450 Hv or less,
Wherein in the cross section in the direction of connection between the first electrode and the conductive particles the second electrode, the connection distance collision caused parts that put on the conductive particles and said first electrode is 0.3μm or more, A connection structure having a size of 4.0 μm or less.   In the cross section in the connection direction of the first electrode, the conductive particles, and the second electrode, the connection distance between the conductive particles and the first electrode is 0.5 μm or more and 5.0 μm or less. The connection structure according to claim 1.   The connection structure according to claim 1 or 2, wherein the conductive particles have base particles and conductive portions arranged on the surface of the base particles.   The connection structure according to claim 3, wherein the base particle is a core-shell particle having an organic core and an inorganic shell disposed on the surface of the organic core.   The connection structure according to claim 3 or 4, wherein a particle diameter of the base particle contained in the conductive material is 1 µm or more and 5 µm or less. Wherein in the cross section in the direction of connection between the first electrode and the conductive particles the second electrode, the connection distance collision caused parts that put on the conductive particles and the second electrode is 0.3μm or more, The connection structure according to claim 1, wherein the connection structure is 4.0 μm or less.   In the cross section in the connection direction of the first electrode, the conductive particles, and the second electrode, the connection distance between the conductive particles and the second electrode is 0.5 μm or more and 5.0 μm or less. The connection structure according to any one of claims 1 to 6.   In the cross section in the connecting direction of the first electrode, the conductive particles, and the second electrode, the number of the protrusions of the conductive particles in contact with the first electrode is 2 or more and 50 or less. The connection structure according to any one of claims 1 to 7, wherein