WO2015141342A1 - 異方性導電接着剤 - Google Patents

異方性導電接着剤 Download PDF

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Publication number
WO2015141342A1
WO2015141342A1 PCT/JP2015/053956 JP2015053956W WO2015141342A1 WO 2015141342 A1 WO2015141342 A1 WO 2015141342A1 JP 2015053956 W JP2015053956 W JP 2015053956W WO 2015141342 A1 WO2015141342 A1 WO 2015141342A1
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Prior art keywords
particles
conductive
solder
conductive particles
volume
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PCT/JP2015/053956
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English (en)
French (fr)
Inventor
明 石神
士行 蟹澤
秀次 波木
青木　正治
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デクセリアルズ株式会社
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Publication of WO2015141342A1 publication Critical patent/WO2015141342A1/ja

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    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
    • C09J9/02—Electrically-conducting adhesives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • H—ELECTRICITY
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    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
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    • H01L2224/81193—Arrangement of the bump connectors prior to mounting wherein the bump connectors are disposed on both the semiconductor or solid-state body and another item or body to be connected to the semiconductor or solid-state body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
    • H01L2224/8119—Arrangement of the bump connectors prior to mounting
    • H01L2224/81194—Lateral distribution of the bump connectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
    • H01L2224/812—Applying energy for connecting
    • H01L2224/81201—Compression bonding
    • H01L2224/81203—Thermocompression bonding, e.g. diffusion bonding, pressure joining, thermocompression welding or solid-state welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L24/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L24/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/62—Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
    • H05K1/0203—Cooling of mounted components
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • H05K1/111—Pads for surface mounting, e.g. lay-out
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    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
    • H05K2201/0203—Fillers and particles
    • H05K2201/0206—Materials
    • H05K2201/0221—Insulating particles having an electrically conductive coating
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    • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
    • H05K2201/0203—Fillers and particles
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    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
    • H05K2201/0203—Fillers and particles
    • H05K2201/0263—Details about a collection of particles
    • H05K2201/0272—Mixed conductive particles, i.e. using different conductive particles, e.g. differing in shape
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    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/03—Conductive materials
    • H05K2201/0332—Structure of the conductor
    • H05K2201/0388—Other aspects of conductors
    • H05K2201/0391—Using different types of conductors
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    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09209—Shape and layout details of conductors
    • H05K2201/09372—Pads and lands
    • H05K2201/09427—Special relation between the location or dimension of a pad or land and the location or dimension of a terminal
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
    • H05K2201/10007—Types of components
    • H05K2201/10106—Light emitting diode [LED]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
    • H05K2201/10431—Details of mounted components
    • H05K2201/10439—Position of a single component
    • H05K2201/10469—Asymmetrically mounted component
    • H—ELECTRICITY
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    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/20—Details of printed circuits not provided for in H05K2201/01 - H05K2201/10
    • H05K2201/2054—Light-reflecting surface, e.g. conductors, substrates, coatings, dielectrics

Definitions

  • the present invention relates to an anisotropic conductive adhesive in which conductive particles are dispersed, and in particular, can dissipate heat generated by a chip (element) such as an LED (Light Emitting Diode) or a driver IC (Integrated Circuit).
  • a chip such as an LED (Light Emitting Diode) or a driver IC (Integrated Circuit).
  • the present invention relates to an anisotropic conductive adhesive.
  • a wire bond method has been used as a method of mounting LED elements on a substrate.
  • the electrodes (first conductivity type electrode 104a and second conductivity type electrode 102a) of the LED element face upward, and the LED element and the substrate are electrically joined. Is performed by wire bonding (WB) 301a and 301b, and a die bonding material 302 is used for bonding the LED element and the substrate.
  • WB wire bonding
  • the LED element electrodes face the substrate side (face down, flip chip) as shown in FIG.
  • the electrode surface of the LED element is directed to the substrate side (face down, flip chip), and the electrical connection and adhesion between the LED element and the substrate are insulative.
  • an anisotropic conductive adhesive in which conductive particles 306 are dispersed in an adhesive binder 305. Since the anisotropic conductive adhesive has a short bonding process, the production efficiency is good.
  • An anisotropic conductive adhesive is inexpensive and excellent in transparency, adhesiveness, heat resistance, mechanical strength, electrical insulation, and the like.
  • FC mounting LED element can be designed to have a large electrode area by the passivation 105, bumpless mounting is possible. Further, the light extraction efficiency is improved by providing a reflective film under the light emitting layer.
  • Gold-tin eutectic bonding is a method in which a chip electrode is formed of an alloy 307 of gold and tin, a flux is applied to a substrate, the chip is mounted and heated, and eutectic bonding is performed with the substrate electrode.
  • solder connection method has a bad yield because there is an adverse effect on reliability due to chip displacement during heating or flux that could not be cleaned.
  • advanced mounting technology is required.
  • solder connection method As a method not using gold-tin eutectic, there is a solder connection method using a solder paste 303 for electrical connection between the electrode surface of the LED element and the substrate, as shown in FIG.
  • solder connection method since the paste has isotropic conductivity, the pn electrodes are short-circuited and the yield is poor.
  • the electrical connection and adhesion between the LED element and the substrate as in FIG. 7, ACF in which conductive particles 306 are dispersed in an insulating binder are used.
  • ACF in which conductive particles 306 are dispersed in an insulating binder are used.
  • anisotropic conductive adhesive is filled with an insulating binder between the pn electrodes. Accordingly, the yield is good because short-circuiting hardly occurs. Moreover, since the bonding process is short, the production efficiency is good.
  • the active layer 103 is located on the substrate side, so that heat is efficiently transmitted to the substrate side.
  • FIGS. 6 and 9 when the electrodes are joined with the conductive pastes 303a and 303b, heat can be radiated with high efficiency, but the connection with the conductive pastes 303a and 303b is as described above. Connection reliability is poor. Also, as shown in FIG. 8, when gold-tin eutectic bonding is performed, the connection reliability is poor as described above.
  • flip chip mounting can be performed with an anisotropic conductive adhesive such as ACF (Anisotropic conductive film) or ACP (Anisotropic Conductive Paste) without using the conductive pastes 303a and 303b.
  • ACF Anisotropic conductive film
  • ACP Anisotropic Conductive Paste
  • the present invention has been proposed in view of such a conventional situation, and provides an anisotropic conductive adhesive capable of obtaining high heat dissipation characteristics.
  • the present inventor has found that the above-mentioned results are obtained by blending conductive particles having a conductive metal layer formed on the surface of resin particles and solder particles having an average particle size smaller than the conductive particles.
  • the inventors have found that the object can be achieved, and have completed the present invention.
  • the anisotropic conductive adhesive according to the present invention includes conductive particles in which a conductive metal layer is formed on the surface of resin particles, solder particles having an average particle size smaller than the conductive particles, and the conductive It contains particles and a binder for dispersing the solder particles.
  • connection structure includes a first electronic component, a second electronic component, conductive particles in which a conductive metal layer is formed on the surface of the resin particles, and an average than the conductive particles.
  • the terminal of the first electronic component and the terminal of the second electronic component are electrically connected via the conductive particles, and the solder particles It is characterized by being soldered.
  • the conductive particles are flattened by pressing during crimping to electrically connect the terminals, and the terminals are soldered together by solder particles having an average particle size smaller than that of the conductive particles.
  • the contact area between the terminals to be increased increases, and high heat dissipation characteristics can be obtained.
  • FIG. 1 is a cross-sectional view schematically showing between opposing terminals before crimping.
  • FIG. 2 is a cross-sectional view schematically showing between terminals facing each other after crimping.
  • FIG. 3 is a cross-sectional view showing an example of an LED mounting body according to an embodiment of the present invention.
  • FIG. 4 is a cross-sectional view showing an example of an LED mounting body according to another embodiment of the present invention.
  • FIG. 5 is a cross-sectional view showing an example of an LED package by a conventional wire bond method.
  • FIG. 6 is a cross-sectional view showing an example of an LED mounting body using a conventional conductive paste.
  • FIG. 7 is a cross-sectional view showing an example of an LED mounting body using a conventional anisotropic conductive adhesive.
  • FIG. 8 is a cross-sectional view showing an example of an LED mounting body in which a conventional FC mounting LED is mounted by gold-tin eutectic bonding.
  • FIG. 9 is a cross-sectional view showing an example of an LED mounting body in which a conventional FC mounting LED is mounted with a conductive paste.
  • FIG. 10 is a cross-sectional view showing an example of an LED mounting body in which a conventional FC mounting LED is mounted with an anisotropic conductive adhesive.
  • the anisotropic conductive adhesive in the present embodiment includes a binder (adhesive component) composed of conductive particles having a conductive metal layer formed on the surface of resin particles and solder particles having an average particle size smaller than that of the conductive particles. ) And the shape thereof is a paste, a film, etc., and can be appropriately selected according to the purpose.
  • FIG. 1 and FIG. 2 are cross-sectional views schematically showing the terminals facing each other before and after crimping, respectively.
  • the solder particles 32 having an average particle size smaller than that of the conductive particles 31 are crushed following the flat deformation of the conductive particles 31 during the press bonding, and are metal-bonded by soldering by heating. For this reason, the area which contacts a terminal increases and can improve a thermal radiation characteristic and an electrical property.
  • the solder particles 32 are larger than the conductive particles 31, leakage may occur and the yield may be deteriorated.
  • the conductive particles 31 are deformed flat by pressing at the time of pressure bonding and elastic repulsion occurs against the deformation, the electrical connection state can be maintained.
  • the conductive particles of the resin core relieve stress generated due to the difference in thermal expansion between the substrate and the element, it is possible to prevent cracks from occurring in the solder joints and improve connection reliability.
  • the conductive particles are metal-coated resin particles in which a conductive metal layer is formed on the surface of the resin particles.
  • the resin particles include epoxy resins, phenol resins, acrylic resins, acrylonitrile / styrene (AS) resins, benzoguanamine resins, divinylbenzene resins, styrene resins, and the like.
  • the metal of the conductive metal layer include Au, Ni, Ag, and Zn. Since such metal-coated resin particles are easily crushed and easily deformed during compression, the contact area with the wiring pattern can be increased. In addition, variations in the wiring pattern height can be absorbed and connection reliability can be improved.
  • the average particle diameter of the conductive particles is preferably 1 ⁇ m or more and 10 ⁇ m or less, more preferably 1 ⁇ m or more and 8 ⁇ m or less. Moreover, it is preferable that the compounding quantity of electroconductive particle is 1 to 100 mass parts with respect to 100 mass parts of binders from a viewpoint of connection reliability and insulation reliability.
  • the solder particles have an average particle size smaller than that of the conductive particles.
  • the average particle size of the solder particles is 20% or more and less than 100% of the average particle size of the conductive particles. If the solder particles are too small relative to the conductive particles, the solder particles are not captured between the terminals facing each other at the time of pressure bonding, and metal bonding is not performed, so that excellent heat dissipation characteristics and electrical characteristics cannot be obtained. On the other hand, if the solder particles are too large with respect to the conductive particles, for example, a shoulder touch due to the solder particles occurs at the edge portion of the LED chip, a leak occurs, and the product yield deteriorates.
  • the solder particles are, for example, Sn-Pb series, Pb-Sn-Sb series, Sn-Sb series, Sn-Pb-Bi series, Bi-Sn series, Sn-Cu series, as defined in JIS Z 3282-1999, It can be appropriately selected from Sn—Pb—Cu, Sn—In, Sn—Ag, Sn—Pb—Ag, Pb—Ag, and the like according to the electrode material and connection conditions. Further, the shape of the solder particles can be appropriately selected from granular, flake shaped, and the like. Note that the solder particles may be covered with an insulating layer in order to improve anisotropy.
  • the blending amount of the solder particles is preferably 1% by volume or more and 30% by volume or less. If the blending amount of the solder particles is too small, excellent heat dissipation characteristics cannot be obtained, and if the blending amount is too large, anisotropy is impaired and excellent connection reliability cannot be obtained.
  • the blending amount of the solder particles is preferably 1% by volume to 30% by volume, and the blending amount of the conductive particles is preferably 1% by volume to 20% by volume.
  • the heat dissipation characteristics and connection reliability of the connection structure can be improved.
  • the compounding quantity of a solder particle is larger than the compounding quantity of electroconductive particle.
  • the blending amount of the solder particles is 10% by volume or more and 30% by volume or less, the blending amount of the conductive particles is 1% by volume or more and 15% by volume or less, and the blending amount of the solder particles is larger than that of the conductive particles. It is also preferable that there are many. By such blending, the thermal resistance value is reduced, and excellent heat dissipation characteristics can be obtained.
  • an adhesive composition used in a conventional anisotropic conductive adhesive or anisotropic conductive film can be used.
  • Preferred examples of the adhesive composition include an epoxy curable adhesive mainly composed of an alicyclic epoxy compound, a heterocyclic epoxy compound, a hydrogenated epoxy compound, or the like.
  • Preferred examples of the alicyclic epoxy compound include those having two or more epoxy groups in the molecule. These may be liquid or solid. Specific examples include glycidyl hexahydrobisphenol A, 3,4-epoxycyclohexenylmethyl-3 ', 4'-epoxycyclohexene carboxylate, and the like. Among them, 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate is preferred because it can ensure light transmission suitable for mounting LED elements on the cured product and is excellent in rapid curing. Can be preferably used.
  • heterocyclic epoxy compound examples include an epoxy compound having a triazine ring, and particularly preferably 1,3,5-tris (2,3-epoxypropyl) -1,3,5-triazine-2,4, Mention may be made of 6- (1H, 3H, 5H) -trione.
  • water-added epoxy compound hydrogenated products of the above-described alicyclic epoxy compounds and heterocyclic epoxy compounds, and other known hydrogenated epoxy resins can be used.
  • the alicyclic epoxy compound, heterocyclic epoxy compound and hydrogenated epoxy compound may be used alone, but two or more kinds may be used in combination.
  • other epoxy compounds may be used in combination as long as the effects of the present invention are not impaired.
  • the curing agent examples include acid anhydrides, imidazole compounds, and dicyan.
  • acid anhydrides that are difficult to discolor the cured product particularly alicyclic acid anhydride-based curing agents, can be preferably used.
  • methylhexahydrophthalic anhydride etc. can be mentioned preferably.
  • the amount of each used is an uncured epoxy compound if there is too little alicyclic acid anhydride curing agent. If the amount is too large, corrosion of the adherend material tends to be accelerated due to the influence of the excess curing agent. Therefore, the alicyclic acid anhydride curing agent is added to 100 parts by mass of the alicyclic epoxy compound.
  • the ratio is preferably 80 to 120 parts by mass, more preferably 95 to 105 parts by mass.
  • the solder particles 32 having an average particle size smaller than that of the conductive particles 31 are crushed following the flat deformation of the conductive particles 31 at the time of pressure bonding, and metal is formed by soldering by heating. Join. For this reason, the area which contacts a terminal increases and can improve a thermal radiation characteristic and an electrical property.
  • connection structure and manufacturing method thereof includes a first electronic component, a second electronic component, conductive particles in which a conductive metal layer is formed on the surface of resin particles, and an average particle diameter larger than that of the conductive particles.
  • Anisotropic conductive film formed by bonding the first electronic component and the second electronic component with an anisotropic conductive adhesive containing small solder particles, conductive particles and a binder for dispersing the solder particles The terminal of the first electronic component and the terminal of the second electronic component are electrically connected via the conductive particles and are soldered by the solder particles.
  • a chip such as an LED (Light Emitting Diode) that generates heat or a driver IC (Integrated Circuit) is suitable, and a chip is used as the second electronic component.
  • a substrate to be mounted is suitable.
  • FIG. 3 is a cross-sectional view showing a configuration example of the LED mounting body.
  • This LED mounting body is an anisotropic conductive adhesive in which an LED element and a substrate, the conductive particles 31 described above, and solder particles 32 having an average particle size smaller than the conductive particles are dispersed in an adhesive component. It is connected using.
  • the LED element includes, for example, a first conductive clad layer 12 made of, for example, n-GaN, an active layer 13 made of, for example, an In x Al y Ga 1-xy N layer, on an element substrate 11 made of, for example, sapphire, and a second conductivity type cladding layer 14 made of p-GaN, and has a so-called double heterostructure. Further, a first conductivity type electrode 12 a is provided on a part of the first conductivity type cladding layer 12, and a second conductivity type electrode 14 a is provided on a part of the second conductivity type cladding layer 14. When a voltage is applied between the first conductivity type electrode 12a and the second conductivity type electrode 14a of the LED element, carriers are concentrated on the active layer 13 and recombination causes light emission.
  • the substrate includes a circuit pattern 22 for the first conductivity type and a circuit pattern 23 for the second conductivity type on the base material 21, and positions corresponding to the first conductivity type electrode 12a and the second conductivity type electrode 14a of the LED element. Each have an electrode 22a and an electrode 23a.
  • the terminals (electrodes 12a and 14a) of the LED element and the terminals (electrodes 22a and 23a) of the substrate are electrically connected via the conductive particles 31, and Metal bonding is performed by solder bonding using the solder particles 32.
  • the contact area between the terminals is increased, the heat generated in the active layer 13 of the LED element can be efficiently released to the substrate side, the decrease in the light emission efficiency can be prevented, and the LED mounting body can be extended in life. it can.
  • the LED element for flip chip mounting is designed such that the terminals (electrodes 12a, 14a) of the LED element are large due to the passivation 105, and therefore the terminals (electrodes 12a, 14a) of the LED element. ) And the terminals (circuit patterns 22 and 23) of the substrate, more conductive particles 31 and solder particles 32 are captured. Thereby, the heat generated in the active layer 13 of the LED element can be released to the substrate side more efficiently.
  • the method for manufacturing a connection structure in the present embodiment includes the above-described conductive particles, solder particles having an average particle size smaller than the conductive particles, and anisotropic particles containing the conductive particles and a binder that disperses the solder particles.
  • the conductive adhesive is sandwiched between the terminal of the first electronic component and the terminal of the second electronic component, and the first electronic component and the second electronic component are thermocompression bonded. Thereby, the terminal of the first electronic component and the terminal of the second electronic component are electrically connected via the conductive particles, and the terminal of the first electronic component and the terminal of the second electronic component are further connected.
  • solder particles having an average particle size smaller than the conductive particles
  • anisotropic particles containing the conductive particles and a binder that disperses the solder particles.
  • the conductive particles are deformed flat by pressing and electrically connected at the time of crimping, and the contact area between the terminals facing each other by solder bonding with the solder particles is increased. Since it increases, high heat dissipation and high connection reliability can be obtained.
  • Example> Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.
  • ACP anisotropic conductive adhesive
  • LED mounting body was produced, and heat dissipation characteristics, leakage current, and electrical characteristics were evaluated.
  • the production of the anisotropic conductive adhesive, the production of the LED mounting body, the evaluation of the heat dissipation characteristics of the LED mounting body, the evaluation of the leakage current, and the evaluation of the electrical characteristics were performed as follows.
  • anisotropic conductive adhesive [Production of anisotropic conductive adhesive]
  • epoxy curing adhesive epoxy resin (trade name: CEL2021P, manufactured by Daicel Chemical Industries, Ltd.) and acid anhydride (MeHHPA, trade name: MH700, manufactured by Shin Nippon Rika Co., Ltd.)
  • the surface of the crosslinked polystyrene resin particles is coated with Au, and the average particle diameter (D50) is 5.5 ⁇ m conductive particles (product name: AUL705, manufactured by Sekisui Chemical Co., Ltd.) and the predetermined average particle diameter (D50).
  • An anisotropic conductive adhesive was prepared by blending with solder particles.
  • Solder particles having an average particle diameter (D50) of 0.8 ⁇ m, 1.1 ⁇ m, 5.0 ⁇ m, 10.0 ⁇ m, and 20.0 ⁇ m were prepared (trade name: M707, manufactured by Senju Metal Industry Co., Ltd.).
  • Table 1 shows the evaluation results of heat dissipation characteristics, leakage current, and electrical characteristics for the examples and comparative examples.
  • Example 1 As shown in Table 1, the thermal resistance value of the LED mounting body using ACP in which 1% by volume of conductive particles and 2% by volume of solder particles having an average particle diameter of 5.0 ⁇ m are added to the binder is 21.0 ° C. / W, the thermal resistance value was lower than that of Comparative Example 1, and the heat dissipation characteristics of the LED mounted body could be improved. Further, the number of leaks was zero, and the product yield rate was 100%. In addition, the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours. . Moreover, the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • Example 2 As shown in Table 1, the thermal resistance of the LED package using ACP in which 2% by volume of conductive particles and 5% by volume of solder particles having an average particle diameter of 5.0 ⁇ m are added to the binder is 13.2 ° C. / W, the thermal resistance value was lower than that of Comparative Example 1, and the heat dissipation characteristics of the LED mounted body could be improved. Further, the number of leaks was zero, and the product yield rate was 100%.
  • the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours. .
  • the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • Example 3 As shown in Table 1, the thermal resistance value of the LED package using ACP in which 2% by volume of conductive particles and 10% by volume of solder particles having an average particle diameter of 5.0 ⁇ m are added to the binder is 11.8 ° C. / W, the thermal resistance value was lower than that of Comparative Example 1, and the heat dissipation characteristics of the LED mounted body could be improved. Further, the number of leaks was zero, and the product yield rate was 100%.
  • the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours. .
  • the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • Example 4 As shown in Table 1, the thermal resistance value of the LED mounting body using ACP in which 15% by volume of conductive particles and 16% by volume of solder particles having an average particle diameter of 5.0 ⁇ m are added to the binder is 11.0 ° C. / W, the thermal resistance value was lower than that of Comparative Example 1, and the heat dissipation characteristics of the LED mounted body could be improved. Further, the number of leaks was zero, and the product yield rate was 100%. In addition, the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours. . Moreover, the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • Example 5 As shown in Table 1, the thermal resistance value of the LED package using ACP in which 2% by volume of conductive particles and 25% by volume of solder particles having an average particle diameter of 5.0 ⁇ m are added to the binder is 10.2 ° C. / W, the thermal resistance value was lower than that of Comparative Example 1, and the heat dissipation characteristics of the LED mounted body could be improved. Further, the number of leaks was zero, and the product yield rate was 100%.
  • the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours. .
  • the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • Example 6> As shown in Table 1, the thermal resistance value of the LED mounted body using ACP in which 1% by volume of conductive particles and 30% by volume of solder particles having an average particle diameter of 5.0 ⁇ m are added to the binder is 10.0 ° C. / W, the thermal resistance value was lower than that of Comparative Example 1, and the heat dissipation characteristics of the LED mounted body could be improved. Further, the number of leaks was zero, and the product yield rate was 100%. In addition, the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours. . Moreover, the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • Example 7 As shown in Table 1, the thermal resistance of the LED package using ACP in which 2% by volume of conductive particles and 5% by volume of solder particles having an average particle size of 1.1 ⁇ m are added to the binder is 13.6 ° C. / W, the thermal resistance value was lower than that of Comparative Example 1, and the heat dissipation characteristics of the LED mounted body could be improved. Further, the number of leaks was zero, and the product yield rate was 100%.
  • the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours. .
  • the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • the evaluation result of the high temperature and high humidity test of the electrical characteristics is ⁇ in the initial stage, and ⁇ after the test, and in the lighting test under the 85 ° C. and 85% RH environment, the fluctuation from the initial Vf value is 5% or more after 3000 hours. became.
  • the evaluation result of the thermal shock test of electrical characteristics was ⁇ at the initial stage, and ⁇ after the test, and continuity breakage (OPEN) occurred after 3000 cycles of the thermal shock test. This is considered that the solder connection part was cracked by the thermal shock test.
  • the evaluation result of the high temperature and high humidity test of the electrical characteristics is ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours .
  • the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • the evaluation results of the high temperature and high humidity test of the electrical characteristics were ⁇ at the initial stage and ⁇ after the test, and in the lighting test under the environment of 85 ° C. and 85% RH, good electrical connection reliability was obtained even after 3000 hours.
  • the evaluation results of the thermal shock test of electrical characteristics were “good” at the initial stage and “good” after the test, and good electrical connection reliability was obtained even after 3000 cycles of the thermal shock test.
  • the heat dissipation characteristics of the LED package could be improved by blending solder particles having an average particle size smaller than that of the conductive particles. Further, as in Examples 1 to 8, when the average particle size of the solder particles was 20% or more and less than 100% of the average particle size of the conductive particles, the product yield could be improved.
  • the blending amount of the solder particles is 1% by volume to 30% by volume, and the blending amount of the conductive particles is 1% by volume to 20% by volume.
  • the heat dissipation characteristics and electrical characteristics of the LED mounting body could be improved.
  • the amount of solder particles added was larger than that of conductive particles, so that anisotropy was improved and electrical characteristics could be improved.
  • the blending amount of the solder particles is 10% by volume to 30% by volume
  • the blending amount of the conductive particles is 1% by volume to 15% by volume
  • the solder particles When the blending amount is larger than the blending amount of the conductive particles, an excellent heat dissipation characteristic having a thermal resistance value of 12 ° C./W or less could be obtained.

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Abstract

　高い放熱特性を得ることができる異方性導電接着剤を提供する。樹脂粒子の表面に導電性金属層が形成された導電性粒子（３１）と、導電性粒子よりも平均粒径が小さいはんだ粒子（３２）と、導電性粒子（３１）及びはんだ粒子（３２）を分散させるバインダーとを含有する。圧着時に導電性粒子（３１）が押圧により扁平変形して端子間を電気的に接続するとともに、導電性粒子（３１）よりも平均粒径が小さいはんだ粒子（３２）により端子間をはんだ接合するため、対向する端子間の接触面積が増加し、高い放熱特性を得ることができる。

Description

異方性導電接着剤
　本発明は、導電性粒子が分散された異方性導電接着剤に関し、特に、ＬＥＤ（Light Emitting Diode）、ドライバーＩＣ（Integrated Circuit）等のチップ（素子）が発する熱を放熱することが可能な異方性導電接着剤に関する。本出願は、日本国において２０１４年３月１９日に出願された日本特許出願番号特願２０１４－５６２６２を基礎として優先権を主張するものであり、この出願は参照されることにより、本出願に援用される。
　従来、ＬＥＤ素子を基板に実装する工法として、ワイヤーボンド工法が用いられている。ワイヤーボンド工法は、図５に示すように、ＬＥＤ素子の電極（第１導電型電極１０４ａ及び第２導電型電極１０２ａ）面を上に向け（フェイスアップ）、そのＬＥＤ素子と基板の電気的接合をワイヤーボンド（ＷＢ）３０１ａ、３０１ｂで行い、ＬＥＤ素子と基板との接着には、ダイボンド材３０２を用いる。
　しかし、このようなワイヤーボンドで電気的接続を得る方法では、電極（第１導電型電極１０４ａ及び第２導電型電極１０２ａ）からのワイヤーボンドの物理的破断・剥離のリスクがあるため、より信頼性の高い技術が求められる。さらに、ダイボンド材３０２の硬化プロセスは、オーブン硬化で行われるため、生産に時間が掛かる。
　ワイヤーボンドを用いない工法として、図６に示すように、ＬＥＤ素子の電極（第１導電型電極１０４ａ及び第２導電型電極１０２ａ）面を基板側に向け(フェイスダウン、フリップチップ)、そのＬＥＤ素子と基板との電気的接続に、銀ペーストに代表される導電性ベースト３０３ａ、３０３ｂを用いる方法がある。
　しかし、導電性ペースト３０３ａ、３０３ｂは、接着力が弱いため、封止樹脂３０４による補強が必要である。さらに、封止樹脂３０４の硬化プロセスは、オーブン硬化で行われるため、生産に時間が掛かる。
　導電性ペーストを用いない工法として、図７に示すように、ＬＥＤ素子の電極面を基板側に向け(フェイスダウン、フリップチップ)、そのＬＥＤ素子と基板との電気的接続及び接着に、絶縁性の接着剤バインダー３０５中に導電性粒子３０６を分散させた異方性導電接着剤を用いる方法がある。異方性導電接着剤は、接着プロセスが短いため、生産効率が良い。また、異方性導電接着剤は、安価であり、透明性、接着性、耐熱性、機械的強度、電気絶縁性等に優れている。
　また、近年、フリップチップ実装するためのＬＥＤ素子が開発されている。このＦＣ実装用ＬＥＤ素子は、パッシベーション１０５により、電極面積を大きく取る設計が可能であるため、バンプレス実装が可能となる。また、発光層の下に反射膜を設けることによって光取り出し効率が良くなる。
　ＦＣ実装用ＬＥＤ素子を基板に実装する工法としては、図８に示すように、金スズ共晶接合が用いられている。金スズ共晶接合は、チップ電極を金とスズの合金３０７で形成し、フラックスを基板に塗布し、チップを搭載、加熱することで基板電極と、共晶接合させる工法である。しかし、このようなはんだ接続工法は、加熱中のチップズレや洗浄しきれなかったフラックスによる信頼性への悪影響があるため歩留まりが悪い。また、高度な実装技術が必要である。
　金スズ共晶を用いない工法として、図９に示すように、ＬＥＤ素子の電極面と基板との電気的接続に、はんだペースト３０３を用いるはんだ接続工法がある。しかし、このようなはんだ接続工法は、ペーストが等方性の導電性を有するため、ｐｎ電極間がショートしてしまい歩留まりが悪い。
　はんだペーストを用いない工法として、図１０に示すように、ＬＥＤ素子と基板との電気的接続及び接着に、図７と同様、絶縁性のバインダー中に導電性粒子３０６を分散させたＡＣＦなどの異方性導電接着剤を用いる方法がある。異方性導電接着剤は、ｐｎ電極間に絶縁性のバインダーが充填される。よって、ショートが発生しにくいため歩留まりが良い。また、接着プロセスが短いため、生産効率が良い。
　ところで、ＬＥＤ素子の活性層（ジャンクション）１０３は、光の他に多くの熱を発生し、発光層温度（Ｔｊ＝ジャンクション温度）が１００℃以上になると、ＬＥＤの発光効率が低下し、ＬＥＤの寿命が短くなる。このため、活性層１０３の熱を効率良く逃がすための構造が必要である。
　図５に示すようなＷＢ実装では、活性層１０３がＬＥＤ素子の上側に位置するため、発生した熱が基板側に効率良く伝わらないため放熱性が悪い。
　また、図６～図１０に示すようなフリップチップ実装を行うと、活性層１０３が基板側に位置するため、熱が基板側に効率良く伝わる。図６、図９に示すように、電極間を導電性ペースト３０３ａ、３０３ｂで接合した場合、高効率で放熱することができるが、導電性ペースト３０３ａ、３０３ｂによる接続は、上記で述べたように接続信頼性が悪い。また、図８に示すように、金スズ共晶接合を行った場合も、上記で述べたのと同様に接続信頼性が悪い。
　また、図７、図１０に示すように、導電性ペースト３０３ａ、３０３ｂを用いずにＡＣＦ（Anisotropic conductive film）やＡＣＰ（Anisotropic Conductive Paste）等の異方性導電接着剤でフリップチップ実装することで、活性層１０３が基板側近く配置され、熱が基板側に効率良く伝わる。また、接着力が高いため、高い接続信頼性が得られる。
特開２００５－１２０３５７号公報 特開平５－１５２４６４号公報 特開２００３－０２６７６３号公報
　しかしながら、従来の異方性導電接着剤を用いたＬＥＤ素子のフリップチップ実装では、電気接続部分の導電性粒子のみが放熱路となるため、ＬＥＤ素子から発生する熱を基板側に十分に逃がすことができず、高い放熱特性を得ることができない。
　本発明は、このような従来の実情に鑑みて提案されたものであり、高い放熱特性を得ることができる異方性導電接着剤を提供する。
　本件発明者は、鋭意検討を行った結果、樹脂粒子の表面に導電性金属層が形成された導電性粒子と、導電性粒子よりも平均粒径が小さいはんだ粒子とを配合することにより、上述の目的を達成できることを見出し、本発明を完成させるに至った。
　すなわち、本発明に係る異方性導電接着剤は、樹脂粒子の表面に導電性金属層が形成された導電性粒子と、前記導電性粒子よりも平均粒径が小さいはんだ粒子と、前記導電性粒子及び前記はんだ粒子を分散させるバインダーとを含有することを特徴とする。
　また、本発明に係る接続構造体は、第１の電子部品と、第２の電子部品と、樹脂粒子の表面に導電性金属層が形成された導電性粒子と、前記導電性粒子よりも平均粒径が小さいはんだ粒子と、前記導電性粒子及び前記はんだ粒子を分散させるバインダーとを含有する異方性導電接着剤により、前記第１の電子部品と前記第２の電子部品とを接着してなる異方性導電膜とを備え、前記第１の電子部品の端子と前記第２の電子部品の端子とが、前記導電性粒子を介して電気的に接続されてなるとともに、前記はんだ粒子によってはんだ接合されてなることを特徴としている。
　本発明によれば、圧着時に導電性粒子が押圧により扁平変形して端子間を電気的に接続するとともに、導電性粒子よりも平均粒径が小さいはんだ粒子により端子間をはんだ接合するため、対向する端子間の接触面積が増加し、高い放熱特性を得ることができる。
図１は、圧着前における対向する端子間を模式的に示す断面図である。 図２は、圧着後における対向する端子間を模式的に示す断面図である。 図３は、本発明の一実施の形態に係るＬＥＤ実装体の一例を示す断面図である。 図４は、本発明の他の一実施の形態に係るＬＥＤ実装体の一例を示す断面図である。 図５は、従来のワイヤーボンド工法によるＬＥＤ実装体の一例を示す断面図である。 図６は、従来の導電性ペーストを用いたＬＥＤ実装体の一例を示す断面図である。 図７は、従来の異方性導電接着剤を用いたＬＥＤ実装体の一例を示す断面図である。 図８は、従来のＦＣ実装用ＬＥＤを金スズ共晶接合により実装したＬＥＤ実装体の一例を示す断面図である。 図９は、従来のＦＣ実装用ＬＥＤを導電性ペーストにより実装したＬＥＤ実装体の一例を示す断面図である。 図１０は、従来のＦＣ実装用ＬＥＤを異方性導電接着剤により実装したＬＥＤ実装体の一例を示す断面図である。
　以下、本発明の実施の形態について、図面を参照しながら下記順序にて詳細に説明する。
１．異方性導電接着剤
２．接続構造体及びその製造方法
３．実施例
　＜１．異方性導電接着剤＞
　本実施の形態における異方性導電接着剤は、樹脂粒子の表面に導電性金属層が形成された導電性粒子と、導電性粒子よりも平均粒径が小さいはんだ粒子とがバインダー（接着剤成分）中に分散されたものであり、その形状は、ペースト、フィルムなどであり、目的に応じて適宜選択することができる。
　図１及び図２は、それぞれ圧着前及び圧着後における対向する端子間を模式的に示す断面図である。図１及び図２に示すように、圧着時に導電性粒子３１よりも平均粒径が小さいはんだ粒子３２が導電性粒子３１の扁平変形に追従して潰れ、加熱によるはんだ接合により金属結合する。このため、端子と接触する面積が増大し、放熱特性及び電気特性を向上させることができる。はんだ粒子３２が導電性粒子３１よりも大きい場合、リークが発生して歩留りが悪くなることがある。
　また、圧着時に導電性粒子３１が押圧により扁平変形し、変形に対する弾性反発が生じるため、電気的な接続状態を維持することができる。また、樹脂コアの導電性粒子が、基板と素子の熱膨張の違いにより発生する応力を緩和させるため、はんだ接合部にクラックが発生するのを防ぎ、接続信頼性を向上させることができる。
　導電性粒子は、樹脂粒子の表面に導電性金属層が形成された金属被覆樹脂粒子である。樹脂粒子としては、エポキシ樹脂、フェノール樹脂、アクリル樹脂、アクリロニトリル・スチレン（ＡＳ）樹脂、ベンゾグアナミン樹脂、ジビニルベンゼン系樹脂、スチレン系樹脂等が挙げられる。導電性金属層の金属としては、Ａｕ、Ｎｉ、Ａｇ、Ｚｎ等が挙げられる。このような金属被覆樹脂粒子は、圧縮時に潰れやすく、変形し易いため、配線パターンとの接触面積を大きくすることができる。また、配線パターンの高さのバラツキを吸収し、接続信頼性を向上させることができる。
　導電性粒子の平均粒径は、１μｍ以上１０μｍ以下であることが好ましく、より好ましくは１μｍ以上８μｍ以下である。また、導電性粒子の配合量は、接続信頼性及び絶縁信頼性の観点から、バインダー１００質量部に対して１質量部以上１００質量部以下であることが好ましい。
　はんだ粒子は、導電性粒子よりも平均粒径が小さく、好ましくは、はんだ粒子の平均粒径は、導電性粒子の平均粒径の２０％以上１００％未満である。はんだ粒子が導電性粒子に対して小さすぎると、圧着時にはんだ粒子が対向する端子間に捕捉されず、金属結合しないため、優れた放熱特性及び電気特性を得ることができない。一方、はんだ粒子が導電性粒子に対して大きすぎると、例えばＬＥＤチップのエッジ部分ではんだ粒子によるショルダータッチが発生してリークが発生し、製品の歩留りが悪くなる。
　はんだ粒子は、例えばＪＩＳ Ｚ ３２８２－１９９９に規定されている、Ｓｎ－Ｐｂ系、Ｐｂ－Ｓｎ－Ｓｂ系、Ｓｎ－Ｓｂ系、Ｓｎ－Ｐｂ－Ｂｉ系、Ｂｉ－Ｓｎ系、Ｓｎ－Ｃｕ系、Ｓｎ－Ｐｂ－Ｃｕ系、Ｓｎ－Ｉｎ系、Ｓｎ－Ａｇ系、Ｓｎ－Ｐｂ－Ａｇ系、Ｐｂ－Ａｇ系などから、電極材料や接続条件などに応じて適宜選択することができる。また、はんだ粒子の形状は、粒状、燐片状などから適宜選択することができる。なお、はんだ粒子は、異方性を向上させるために絶縁層で被覆されていても構わない。
　はんだ粒子の配合量は、１体積％以上３０体積％以下であることが好ましい。はんだ粒子の配合量が少なすぎると優れた放熱特性が得られなくなり、配合量が多すぎると異方性が損なわれ、優れた接続信頼性が得られない。
　また、はんだ粒子の配合量は、１体積％以上３０体積％以下であり、導電性粒子の配合量は、１体積％以上２０体積％以下であることが好ましい。このような配合により、接続構造体の放熱特性、及び接続信頼性を向上させることができる。また、はんだ粒子の配合量は、導電性粒子の配合量よりも多いことが好ましい。はんだ粒子の配合量が導電性粒子の配合量よりも多いことにより、異方性を向上させ、電気特性を向上させることができる。
　また、はんだ粒子の配合量は、１０体積％以上３０体積％以下であり、導電性粒子の配合量は、１体積％以上１５体積％以下であり、はんだ粒子の配合量が、導電性粒子よりも多いことが好ましい。このような配合により、熱抵抗値が小さくなり、優れた放熱特性を得ることができる。
　バインダーとしては、従来の異方性導電接着剤や異方性導電フィルムにおいて使用されている接着剤組成物を利用することができる。接着剤組成物としては、脂環式エポキシ化合物や複素環系エポキシ化合物や水素添加エポキシ化合物等を主成分としたエポキシ硬化系接着剤が好ましく挙げられる。
　脂環式エポキシ化合物としては、分子内に２つ以上のエポキシ基を有するものが好ましく挙げられる。これらは、液状であっても固体状であってもよい。具体的には、グリシジルヘキサヒドロビスフェノールＡ、３，４－エポキシシクロヘキセニルメチル－３’，４’－エポキシシクロヘキセンカルボキシレート等を挙げることができる。中でも、硬化物にＬＥＤ素子の実装等に適した光透過性を確保でき、速硬化性にも優れている点から、３，４－エポキシシクロヘキセニルメチル－３’，４’－エポキシシクロヘキセンカルボキシレートを好ましく使用することができる。
　複素環状エポキシ化合物としては、トリアジン環を有するエポキシ化合物を挙げることができ、特に好ましくは１，３，５－トリス（２，３－エポキシプロピル）－１，３，５－トリアジン－２，４，６－（１Ｈ，３Ｈ，５Ｈ）－トリオンを挙げることができる。
　水添加エポキシ化合物としては、先述の脂環式エポキシ化合物や複素環系エポキシ化合物の水素添加物や、その他公知の水素添加エポキシ樹脂を使用することができる。
　脂環式エポキシ化合物や複素環系エポキシ化合物や水素添加エポキシ化合物は、単独で使用してもよいが、２種以上を併用することができる。また、これらのエポキシ化合物に加えて本発明の効果を損なわない限り、他のエポキシ化合物を併用してもよい。例えば、ビスフェノールＡ、ビスフェノールＦ、ビスフェノールＳ、テトラメチルビスフェノールＡ、ジアリールビスフェノールＡ、ハイドロキノン、カテコール、レゾルシン、クレゾール、テトラブロモビスフェノールＡ、トリヒドロキシビフェニル、ベンゾフェノン、ビスレゾルシノール、ビスフェノールヘキサフルオロアセトン、テトラメチルビスフェノールＡ、テトラメチルビスフェノールＦ、トリス（ヒドロキシフェニル）メタン、ビキシレノール、フェノールノボラック、クレゾールノボラック等の多価フェノールとエピクロルヒドリンとを反応させて得られるグリシジルエーテル；グリセリン、ネオペンチルグリコール、エチレングリコール、プロピレングリコール、ヘキシレングリコール、ポリエチレングリコール、ポリプロピレングリコール等の脂肪族多価アルコールとエピクロルヒドリンとを反応させて得られるポリグリシジルエーテル；ｐ－オキシ安息香酸、β－オキシナフトエ酸のようなヒドロキシカルボン酸とエピクロルヒドリンとを反応させて得られるグリシジルエーテルエステル；フタル酸、メチルフタル酸、イソフタル酸、テレフタル酸、テトラハイドロフタル酸、エンドメチレンテトラハイドロフタル酸、エンドメチレンヘキサハイドロフタル酸、トリメット酸、重合脂肪酸のようなポリカルボン酸から得られるポリグリシジルエステル；アミノフェノール、アミノアルキルフェノールから得られるグリシジルアミノグリシジルエーテル；アミノ安息香酸から得られるグリシジルアミノグリシジルエステル；アニリン、トルイジン、トリブロムアニリン、キシリレンジアミン、ジアミノシクロヘキサン、ビスアミノメチルシクロヘキサン、４，４’－ジアミノジフェニルメタン、４，４’－ジアミノジフェニルスルホン等から得られるグリシジルアミン；エポキシ化ポリオレフィン等の公知のエポキシ樹脂類が挙げられる。
　硬化剤としては、酸無水物、イミダゾール化合物、ジシアン等を挙げることができる。中でも、硬化物を変色させ難い酸無水物、特に脂環式酸無水物系硬化剤を好ましく使用できる。具体的には、メチルヘキサヒドロフタル酸無水物等を好ましく挙げることができる。
　接着剤組成物において、脂環式エポキシ化合物と脂環式酸無水物系硬化剤とを使用する場合、それぞれの使用量は、脂環式酸無水物系硬化剤が少なすぎると未硬化エポキシ化合物が多くなり、多すぎると余剰の硬化剤の影響で被着体材料の腐食が促進される傾向があるので、脂環式エポキシ化合物１００質量部に対し、脂環式酸無水物系硬化剤を、好ましくは８０～１２０質量部、より好ましくは９５～１０５質量部の割合で使用する。
　このような構成からなる異方性導電接着剤は、圧着時に導電性粒子３１よりも平均粒径が小さいはんだ粒子３２が導電性粒子３１の扁平変形に追従して潰れ、加熱によるはんだ接合により金属結合する。このため、端子と接触する面積が増大し、放熱特性及び電気特性を向上させることができる。
　＜２．接続構造体及びその製造方法＞
　次に、前述した異方性導電接着剤を用いた接続構造体について説明する。本実施の形態における接続構造体は、第１の電子部品と、第２の電子部品と、樹脂粒子の表面に導電性金属層が形成された導電性粒子と、導電性粒子よりも平均粒径が小さいはんだ粒子と、導電性粒子及びはんだ粒子を分散させるバインダーとを含有する異方性導電接着剤により、第１の電子部品と第２の電子部品とを接着してなる異方性導電膜とを備え、第１の電子部品の端子と第２の電子部品の端子とが、導電性粒子を介して電気的に接続されているとともに、はんだ粒子によってはんだ接合されている。
　本実施の形態における第１の電子部品としては、熱を発するＬＥＤ（Light Emitting Diode）、ドライバーＩＣ（Integrated Circuit）等のチップ（素子）が好適であり、第２の電子部品としては、チップを搭載する基板が好適である。
　図３は、ＬＥＤ実装体の構成例を示す断面図である。このＬＥＤ実装体は、ＬＥＤ素子と基板とを、前述した導電性粒子３１と、導電性粒子よりも平均粒径が小さいはんだ粒子３２とが接着剤成分中に分散された異方性導電接着剤を用いて接続したものである。
　ＬＥＤ素子は、例えばサファイヤからなる素子基板１１上に、例えばｎ－ＧａＮからなる第１導電型クラッド層１２と、例えばＩｎｘＡｌｙＧａ１－ｘ－ｙＮ層からなる活性層１３と、例えばｐ－ＧａＮからなる第２導電型クラッド層１４とを備え、いわゆるダブルヘテロ構造を有する。また、第１導電型クラッド層１２上の一部に第１導電型電極１２ａを備え、第２導電型クラッド層１４上の一部に第２導電型電極１４ａを備える。ＬＥＤ素子の第１導電型電極１２ａと第２導電型電極１４ａとの間に電圧を印加すると、活性層１３にキャリアが集中し、再結合することにより発光が生じる。
　基板は、基材２１上に第１導電型用回路パターン２２と、第２導電型用回路パターン２３とを備え、ＬＥＤ素子の第１導電型電極１２ａ及び第２導電型電極１４ａに対応する位置にそれぞれ電極２２ａ及び電極２３ａを有する。
　図３に示すように、ＬＥＤ実装体は、ＬＥＤ素子の端子（電極１２ａ、１４ａ）と、基板の端子（電極２２ａ、２３ａ）とが導電性粒子３１を介して電気的に接続され、さらに、はんだ粒子３２によるはんだ接合により金属結合している。これにより、端子間の接触面積が増大し、ＬＥＤ素子の活性層１３で発生した熱を効率良く基板側に逃がすことができ、発光効率の低下を防ぐとともにＬＥＤ実装体を長寿命化させることができる。
　また、フリップチップ実装するためのＬＥＤ素子は、図４に示すように、パッシベーション１０５により、ＬＥＤ素子の端子（電極１２ａ、１４ａ）が大きく設計されているため、ＬＥＤ素子の端子（電極１２ａ、１４ａ）と基板の端子（回路パターン２２、２３）との間に導電性粒子３１及びはんだ粒子３２がより多く捕捉される。これにより、ＬＥＤ素子の活性層１３で発生した熱をさらに効率良く基板側に逃がすことができる。
　次に、上述した接続構造体の製造方法について説明する。本実施の形態における接続構造体の製造方法は、前述した導電性粒子と、導電性粒子よりも平均粒径が小さいはんだ粒子と、導電性粒子及びはんだ粒子を分散させるバインダーとを含有する異方性導電接着剤を、第１の電子部品の端子と第２の電子部品の端子との間に挟み、第１の電子部品と第２の電子部品とを熱圧着する。これにより、第１の電子部品の端子と、第２の電子部品の端子とが導電性粒子を介して電気的に接続され、さらに第１の電子部品の端子と第２の電子部品の端子とが、はんだ粒子によるはんだ接合により金属結合した接続構造体を得ることができる。
　本実施の形態における接続構造体の製造方法によれば、圧着時に導電性粒子が押圧により扁平変形して電気的に接続するとともに、はんだ粒子によるはんだ接合により対向する端子間のとの接触面積が増加するため、高い放熱性及び高い接続信頼性を得ることができる。
　＜３．実施例＞
　以下、本発明の実施例について詳細に説明するが、本発明はこれらの実施例に限定されるものではない。本実施例では、導電性粒子とはんだ粒子とを配合した異方性導電接着剤（ＡＣＰ）を作製し、ＬＥＤ実装体を作製し、放熱特性、リーク電流、及び電気特性について評価した。
　異方性導電接着剤の作製、ＬＥＤ実装体の作製、ＬＥＤ実装体の放熱特性の評価、リーク電流の評価、及び電気特性の評価は、次のように行った。
　［異方性導電接着剤の作製］
　エポキシ硬化系接着剤（エポキシ樹脂（商品名：ＣＥＬ２０２１Ｐ、（株）ダイセル化学製）及び酸無水物（ＭｅＨＨＰＡ、商品名：ＭＨ７００、新日本理化（株）製）を主成分としたバインダー）中に、架橋ポリスチレン樹脂粒子の表面にＡｕが被覆された平均粒径（Ｄ５０）が５．５μｍの導電性粒子（品名：ＡＵＬ７０５、積水化学工業社製）と、所定の平均粒径（Ｄ５０）を有するはんだ粒子とを配合し、異方性導電接着剤を作製した。はんだ粒子として、平均粒径（Ｄ５０）が、０．８μｍ、１．１μｍ、５．０μｍ、１０．０μｍ、及び２０．０μｍのものを準備した（商品名：Ｍ７０７、千住金属工業社製）。
　［ＬＥＤ実装体の作製］
　異方性導電接着剤を用いてＦＣ実装用ＬＥＤチップ（商品名：ＤＡ７００、ＣＲＥＥ社製、Ｖｆ＝３．２Ｖ（Ｉｆ＝３５０ｍＡ））をＡｕ電極基板（セラミック基板、導体スペース＝１００μｍＰ、Ｎｉ／Ａｕメッキ＝５．０／０．３μｍ）に搭載した。異方性導電接着剤をＡｕ電極基板に塗布した後、ＬＥＤチップをアライメントして搭載し、２６０℃－１０秒、荷重１０００ｇ／ｃｈｉｐの条件で加熱圧着を行った。
　［放熱特性の評価］
　過渡熱抵抗測定装置（ＣＡＴＳ電子設計社製）を用いて、ＬＥＤ実装体の熱抵抗値（℃／Ｗ）を測定した。測定条件はＩｆ＝３５０ｍＡ（定電流制御）で行った。
　［リーク電流の評価］
　ＬＥＤ実装体に－５Ｖ／１０μＡで通電させ、１μＡ以上のリーク電流があったものをリーク発生としてカウントした。測定はｎ＝１０００で行い、製品の歩留り率（％）を算出した。
　［電気特性の評価］
　初期Ｖｆ値として、Ｉｆ＝３５０ｍＡ時のＶｆ値を測定した。また、８５℃、８５％ＲＨ環境下でＬＥＤ実装体をＩｆ＝３５０ｍＡで５００時間点灯させ（高温高湿試験）、Ｉｆ＝３５０ｍＡ時のＶｆ値を測定した。なお、高温高湿試験は初期良品のみ行った。初期の評価は、端子間のショートを確認した場合を「×」、それ以外を「○」とした。高温高湿試験後の評価は、導通の破断を確認した場合（ＯＰＥＮ）を「×」、初期Ｖｆ値からの変動が５％以上の場合を「△」、初期Ｖｆ値からの変動が５％未満の場合を「○」とした。
　また、－４０℃／３０ｍｉｎ←→１００℃／３０ｍｉｎ、３０００サイクルの熱衝撃試験に投入し、Ｉｆ＝３５０ｍＡ時のＶｆ値を測定した。なお、熱衝撃試験は初期良品のみ行った。初期の評価は、端子間のショートを確認した場合を「×」、それ以外を「○」とした。熱衝撃試験後の評価は、導通の破断を確認した場合（ＯＰＥＮ）を「×」、初期Ｖｆ値からの変動が５％以上の場合を「△」、初期Ｖｆ値からの変動が５％未満の場合を「○」とした。
　表１に、実施例及び比較例について、放熱特性、リーク電流、及び電気特性の評価結果を示す。
Figure JPOXMLDOC01-appb-T000001
　＜実施例１＞
　表１に示すように、バインダーに対して導電性粒子を１体積％、平均粒径５．０μｍのはんだ粒子を２体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は２１．０℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜実施例２＞
　表１に示すように、バインダーに対して導電性粒子を２体積％、平均粒径５．０μｍのはんだ粒子を５体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１３．２℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜実施例３＞
　表１に示すように、バインダーに対して導電性粒子を２体積％、平均粒径５．０μｍのはんだ粒子を１０体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１１．８℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜実施例４＞
　表１に示すように、バインダーに対して導電性粒子を１５体積％、平均粒径５．０μｍのはんだ粒子を１６体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１１．０℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜実施例５＞
　表１に示すように、バインダーに対して導電性粒子を２体積％、平均粒径５．０μｍのはんだ粒子を２５体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１０．２℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜実施例６＞
　表１に示すように、バインダーに対して導電性粒子を１体積％、平均粒径５．０μｍのはんだ粒子を３０体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１０．０℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜実施例７＞
　表１に示すように、バインダーに対して導電性粒子を２体積％、平均粒径１．１μｍのはんだ粒子を５体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１３．６℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜実施例８＞
　表１に示すように、バインダーに対して導電性粒子を２０体積％、平均粒径５．０μｍのはんだ粒子を１０体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１４．５℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で△であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後に初期Ｖｆ値からの変動が５％以上となった。これは、導電性粒子の添加量が過剰なため、はんだ粒子の潰れが不十分であっためと考えられる。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜比較例１＞
　表１に示すように、バインダーに対して導電性粒子を１体積％添加し、はんだ粒子を添加しなかったＡＣＰを用いたＬＥＤ実装体の熱抵抗値は４０．０℃／Ｗであり、良好な放熱特性が得られなかった。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で△であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後に導通の破断（ＯＰＥＮ）が発生した。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜比較例２＞
　表１に示すように、バインダーに対して導電性粒子を４０体積％添加し、はんだ粒子を添加しなかったＡＣＰを用いたＬＥＤ実装体は、初期の評価が×であった。これは、導電性粒子の添加量が過剰なため、異方性が失われたものと考えられる。
　＜比較例３＞
　表１に示すように、バインダーに対して導電性粒子を添加せず、平均粒径５．０μｍのはんだ粒子を５体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１３．２℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で△であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後に導通の破断（ＯＰＥＮ）が発生した。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で×であり、熱衝撃試験３０００サイクル経過後に導通の破断（ＯＰＥＮ）が発生した。これは、熱衝撃試験によって、はんだ接続部分にクラックが入ったものと考えられる。
　＜比較例４＞
　表１に示すように、バインダーに対して導電性粒子を添加せず、平均粒径５．０μｍのはんだ粒子を４０体積％添加したＡＣＰを用いたＬＥＤ実装体は、初期の評価が△であった。これは、はんだ粒子の添加量が過剰なため、異方性が失われたものと考えられる。
　＜比較例５＞
　表１に示すように、バインダーに対して導電性粒子を２体積％、平均粒径１０．０μｍのはんだ粒子を５体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１３．２℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は１６個であり、製品の歩留り率は９８．４％であった。これは、はんだ粒子の平均粒径が大きすぎたため、チップエッジ部分ではんだ粒子によるショルダータッチが発生したものと考えられる。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜比較例６＞
　表１に示すように、バインダーに対して導電性粒子を２体積％、平均粒径２０．０μｍのはんだ粒子を５体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１３．２℃／Ｗであり、比較例１よりも熱抵抗値を低下させ、ＬＥＤ実装体の放熱特性を向上させることができた。また、リーク発生は７２個であり、製品の歩留り率は９２．８％であった。これは、比較例５と同様に、はんだ粒子の平均粒径が大きすぎたため、チップエッジ部分ではんだ粒子によるショルダータッチが発生したものと考えられる。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で○であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後でも良好な電気接続信頼性が得られた。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　＜参考例１＞
　表１に示すように、バインダーに対して導電性粒子を２体積％、平均粒径０．８μｍのはんだ粒子を５体積％添加したＡＣＰを用いたＬＥＤ実装体の熱抵抗値は１９．８℃／Ｗであり、良好な放熱特性が得られなかった。これは、はんだ粒子の平均粒径が小さすぎたため、ＬＥＤチップと基板配線との間で金属結合することができなかったためと考えられる。また、リーク発生は０個であり、製品の歩留り率は１００％であった。また、電気特性の高温高湿試験の評価結果は、初期で○、試験後で×であり、８５℃８５％ＲＨ環境下での点灯試験では３０００ｈ後に導通の破断（ＯＰＥＮ）が発生した。また、電気特性の熱衝撃試験の評価結果は、初期で○、試験後で○であり、熱衝撃試験３０００サイクル経過後でも良好な電気接続信頼性が得られた。
　実施例１～８のように、導電性粒子よりも平均粒径が小さいはんだ粒子を配合することにより、ＬＥＤ実装体の放熱特性を向上させることができた。また、実施例１～８のように、はんだ粒子の平均粒径が、導電性粒子の平均粒径の２０％以上１００％未満であることにより、製品の歩留りを向上させることができた。
　また、実施例１～８のように、はんだ粒子の配合量が、１体積％以上３０体積％以下であり、導電性粒子の配合量が、１体積％以上２０体積％以下であることにより、ＬＥＤ実装体の放熱特性、及び電気特性を向上させることができた。また、実施例１～７のように、はんだ粒子の配合量が、導電性粒子よりも多いことにより、異方性を向上させ、電気特性を向上させることができた。
　また、実施例３～６のように、はんだ粒子の配合量が、１０体積％以上３０体積％以下であり、導電性粒子の配合量が、１体積％以上１５体積％以下であり、はんだ粒子の配合量が、導電性粒子の配合量よりも多いことにより、熱抵抗値が１２℃／Ｗ以下の優れた放熱特性を得ることができた。
　１１　素子基板、１２　第１導電型クラッド層、１３　活性層、１４　第２導電型クラッド層、２１　基材、２２　第１導電型用回路パターン、２３　第２導電型用回路パターン、１５　パッシベーション、３１　導電性粒子、３２　はんだ粒子、３３　バインダー、１０１　素子基板、１０２　第１導電型クラッド層、１０３　活性層、１０４　第２導電型クラッド層、１０５　パッシベーション、２０１　基材、２０２　第１導電型用回路パターン、２０３　第２導電型用回路パターン、３０１　ワイヤーボンド、３０２　ダイボンド材、３０３　導電性ペースト、３０４　封止樹脂、３０５　バインダー、３０６　導電性粒子、３０７　金スズ合金

Claims (8)

  1. 　樹脂粒子の表面に導電性金属層が形成された導電性粒子と、
    　前記導電性粒子よりも平均粒径が小さいはんだ粒子と、
    　前記導電性粒子及び前記はんだ粒子を分散させるバインダーと
    　を含有する異方性導電接着剤。
  2. 　前記はんだ粒子の平均粒径が、前記導電性粒子の平均粒径の２０％以上１００％未満である請求項１記載の異方性導電接着剤。
  3. 　前記はんだ粒子の配合量が、１体積％以上３０体積％以下であり、
    　前記導電性粒子の配合量が、１体積％以上２０体積％以下である請求項１又は２記載の異方性導電接着剤。
  4. 　前記はんだ粒子の配合量が、前記導電性粒子の配合量よりも多い請求項３に記載の異方性導電接着剤。
  5. 　前記はんだ粒子の配合量が、１０体積％以上３０体積％以下であり、
    　前記導電性粒子の配合量が、１体積％以上１５体積％以下であり、
    　前記はんだ粒子の配合量が、前記導電性粒子よりも多い請求項１又は２記載の異方性導電接着剤。
  6. 　第１の電子部品と、
    　第２の電子部品と、
    　樹脂粒子の表面に導電性金属層が形成された導電性粒子と、前記導電性粒子よりも平均粒径が小さいはんだ粒子と、前記導電性粒子及び前記はんだ粒子を分散させるバインダーとを含有する異方性導電接着剤により、前記第１の電子部品と前記第２の電子部品とを接着してなる異方性導電膜とを備え、
    　前記第１の電子部品の端子と前記第２の電子部品の端子とが、前記導電性粒子を介して電気的に接続されてなるとともに、前記はんだ粒子によってはんだ接合されてなる接続構造体。
  7. 　前記第１の電子部品が、ＬＥＤ素子であり、
    　前記第２の電子部品が、基板である請求項６記載の接続構造体。
  8. 　樹脂粒子の表面に導電性金属層が形成された導電性粒子と、前記導電性粒子よりも平均粒径が小さいはんだ粒子と、導電性粒子及びはんだ粒子を分散させるバインダーとを含有する異方性導電接着剤を、第１の電子部品の端子と第２の電子部品の端子との間に挟み、第１の電子部品と第２の電子部品とを熱圧着する接続構造体の製造方法。
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