WO2024034516A1 - 導電ペースト及び接続構造体 - Google Patents

導電ペースト及び接続構造体 Download PDF

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Publication number
WO2024034516A1
WO2024034516A1 PCT/JP2023/028427 JP2023028427W WO2024034516A1 WO 2024034516 A1 WO2024034516 A1 WO 2024034516A1 JP 2023028427 W JP2023028427 W JP 2023028427W WO 2024034516 A1 WO2024034516 A1 WO 2024034516A1
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WIPO (PCT)
Prior art keywords
weight
thixotropic agent
electrode
conductive paste
solder particles
Prior art date
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Ceased
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PCT/JP2023/028427
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English (en)
French (fr)
Japanese (ja)
Inventor
雄太 山中
主 國澤
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Sekisui Chemical Co Ltd
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Sekisui Chemical Co Ltd
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Publication date
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Priority to JP2023562725A priority Critical patent/JP7526371B2/ja
Publication of WO2024034516A1 publication Critical patent/WO2024034516A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400°C
    • 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
    • C09J11/02—Non-macromolecular additives
    • C09J11/04—Non-macromolecular additives inorganic
    • 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
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • 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
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • 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
    • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
    • C09J9/02—Electrically-conducting adhesives
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C12/00—Alloys based on antimony or bismuth
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C13/00—Alloys based on tin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
    • H01B5/16—Non-insulated conductors or conductive bodies characterised by their form comprising conductive material in insulating or poorly conductive material, e.g. conductive rubber
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R11/00—Individual connecting elements providing two or more spaced connecting locations for conductive members which are, or may be, thereby interconnected, e.g. end pieces for wires or cables supported by the wire or cable and having means for facilitating electrical connection to some other wire, terminal, or conductive member, blocks of binding posts
    • H01R11/01—Individual connecting elements providing two or more spaced connecting locations for conductive members which are, or may be, thereby interconnected, e.g. end pieces for wires or cables supported by the wire or cable and having means for facilitating electrical connection to some other wire, terminal, or conductive member, blocks of binding posts characterised by the form or arrangement of the conductive interconnection between the connecting locations
    • 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
    • H05K1/18—Printed circuits structurally associated with non-printed electric components

Definitions

  • the present invention relates to a conductive paste containing solder particles.
  • the present invention also relates to a connected structure using the above conductive paste.
  • Anisotropic conductive materials such as anisotropic conductive paste and anisotropic conductive film are widely known.
  • anisotropic conductive material conductive particles are dispersed in a binder resin.
  • the above-mentioned anisotropic conductive material is used to obtain various connected structures. Connections using the above-mentioned anisotropic conductive materials include, for example, connections between flexible printed circuit boards and glass substrates (FOG (Film on Glass)), connections between semiconductor chips and flexible printed circuit boards (COF (Chip on Film)), and semiconductor Examples include connection between a 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.
  • FOG Flexible printed circuit boards and glass substrates
  • COF Chip on Film
  • semiconductor Examples include connection between a 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.
  • Patent Document 1 discloses a conductive paste containing metal particles as a main component with an average particle diameter of 0.4 ⁇ m to 2.0 ⁇ m.
  • the number of metal particles having a particle diameter of 0.2 ⁇ m or less is 5% or less out of 100% of the total number of metal particles.
  • a plurality of upper electrodes and a plurality of lower electrodes are electrically connected to make a conductive connection.
  • the solder particles are preferably placed between the upper and lower electrodes, and desirably not between adjacent lateral electrodes. It is desirable that adjacent horizontal electrodes are not electrically connected.
  • a conductive paste containing solder particles is placed at a specific position on a substrate by screen printing or the like, and then heated by reflow or the like before use.
  • the conductive paste is heated to a temperature higher than the melting point of the solder particles, the solder particles melt and the solder aggregates between the electrodes, thereby electrically connecting the upper and lower electrodes.
  • the aggregation of the solder particles may be inhibited, and the solder particles may not be efficiently arranged between the upper and lower electrodes to be connected.
  • solder particles contained in the conductive paste may be placed in areas where no electrodes are formed, reducing the amount of solder particles placed between the upper and lower electrodes to be connected. Therefore, the reliability of conduction between the upper and lower electrodes to be connected may be lowered, or the reliability of insulation between adjacent electrodes in the horizontal direction may be lowered.
  • the solder particles include a thermosetting component, a plurality of solder particles, a flux, and a thixotropic agent, and the solder particles have an average particle diameter of 5.0 ⁇ m or less, and the flux , is solid at 25°C, and the thixotropic agent is a liquid at 25°C and has a hydroxyl group, or is solid at 25°C, and the thixotropic agent is A conductive paste is provided which is a thixotropic agent and has the following weight increase rate of 0.2% by weight or more when left at 50% RH for 24 hours.
  • Weight increase rate (weight%) (W2-W1) x 100/W1
  • W1 Weight of the thixotropic agent before standing
  • W2 Weight of the thixotropic agent after standing
  • the content of the thixotropic agent is 0.005% by weight or more and 2% by weight or less in 100% by weight of the conductive paste.
  • the content of the thixotropic agent is 0.003 parts by weight or more and 2 parts by weight or less with respect to 100 parts by weight of the solder particles.
  • the thixotropic agent is a thixotropic agent that is liquid at 25° C. and has a hydroxyl group.
  • the thixotropic agent is a thixotropic agent that is liquid at 25°C, has a hydroxyl group, and has a boiling point of 80°C or higher.
  • the thixotropic agent is a thixotropic agent that is solid at 25° C. and has a weight increase rate of 1% by weight or more.
  • a first connection target member having a first electrode on its surface
  • a second connection target member having a second electrode on its surface
  • the first connection target member a connecting portion connecting the second connection target member, the material of the connecting portion is the above-mentioned conductive paste, and the first electrode and the second electrode are connected to the connecting portion.
  • a connecting structure is provided that is electrically connected by a solder portion therein.
  • the conductive paste according to the present invention includes a thermosetting component, a plurality of solder particles, a flux, and a thixotropic agent.
  • the average particle diameter of the solder particles is 5.0 ⁇ m or less.
  • the flux is solid at 25°C.
  • the thixotropic agent is a thixotropic agent that is liquid at 25°C and has a hydroxyl group, or is solid at 25°C and the thixotropic agent is The thixotropic agent has the above weight increase rate of 0.2% by weight or more when left at 50% RH for 24 hours. Since the conductive paste according to the present invention has the above configuration, it is possible to improve screen printability, maintain tackiness, and efficiently arrange solder particles on electrodes. Can be done.
  • FIG. 1 is a cross-sectional view schematically showing a connected structure obtained using a conductive paste according to an embodiment of the present invention.
  • the conductive paste according to the present invention includes a thermosetting component, a plurality of solder particles, a flux, and a thixotropic agent.
  • the average particle diameter of the solder particles is 5.0 ⁇ m or less.
  • the flux is solid at 25°C.
  • the thixotropic agent is (A) a thixotropic agent that is liquid at 25°C and has a hydroxyl group, or (B) a thixotropic agent that is solid at 25°C and The thixotropic agent has the following weight increase rate of 0.2% by weight or more when the tropic agent is left at 25° C. and 50% RH for 24 hours.
  • Weight increase rate (weight%) (W2-W1) x 100/W1
  • W1 Weight of the thixotropic agent before standing
  • W2 Weight of the thixotropic agent after standing
  • the conductive paste according to the present invention has the above configuration, it is possible to improve screen printability, maintain tackiness, and efficiently arrange solder particles on electrodes. Can be done.
  • a plurality of solder particles easily gather between upper and lower opposing electrodes during conductive connection between electrodes, and a plurality of solder particles can be arranged on an electrode (line).
  • the present invention can effectively increase the continuity reliability between the upper and lower electrodes that should be connected, and can effectively increase the insulation reliability between adjacent lateral electrodes that should not be connected. Can be done.
  • positional displacement between the electrodes can be prevented.
  • the electrodes of the first connection target member and the electrodes of the second connection target member are overlapped. Even in a state where the alignment is misaligned, the misalignment can be corrected and the electrodes can be connected to each other (self-alignment effect).
  • the viscosity ( ⁇ 25) at 25°C of the conductive paste is preferably 30 Pa ⁇ s or more, more preferably 50 Pa ⁇ s or more, and preferably It is 250 Pa ⁇ s or less, more preferably 200 Pa ⁇ s or less.
  • the above viscosity ( ⁇ 25) can be adjusted as appropriate depending on the types and amounts of the ingredients.
  • the above viscosity ( ⁇ 25) can be measured, for example, using an E-type viscometer at 25° C. and 5 rpm.
  • E-type viscometer examples include "TVE22L” manufactured by Toki Sangyo Co., Ltd.
  • the conductive paste is an anisotropic conductive paste.
  • the above-mentioned conductive paste is suitably used for electrical connection of electrodes.
  • the conductive paste is a circuit connection paste.
  • the environment in which the conductive paste is used is not particularly limited.
  • the conductive paste may be used in an environment of 25° C. and 50% RH, or in other environments.
  • (meth)acrylic means one or both of "acrylic” and “methacrylic.”
  • thermosetting component The conductive paste according to the present invention contains a thermosetting component.
  • the conductive paste preferably contains a thermosetting compound as a thermosetting component.
  • the conductive paste may or may not contain a thermosetting agent.
  • the conductive paste may contain a thermosetting compound and a thermosetting agent as thermosetting components. When the conductive paste contains a thermosetting compound and a thermosetting agent, the conductive paste can be cured even better.
  • thermosetting component thermosetting compound
  • the thermosetting compound is not particularly limited.
  • the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth)acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds.
  • the thermosetting compound may be an epoxy compound or an episulfide compound.
  • epoxy compounds are more preferable.
  • the thermosetting compound preferably contains an epoxy compound. .
  • the above thermosetting compounds may be used alone or in combination of two or more.
  • the above epoxy compound is a compound having at least one epoxy group.
  • the above-mentioned epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, phenol novolak type epoxy compounds, biphenyl type epoxy compounds, biphenyl novolac type epoxy compounds, biphenol type epoxy compounds, and naphthalene type epoxy compounds.
  • fluorene type epoxy compound fluorene type epoxy compound, phenol aralkyl type epoxy compound, naphthol aralkyl type epoxy compound, dicyclopentadiene type epoxy compound, anthracene type epoxy compound, epoxy compound having an adamantane skeleton, epoxy compound having a tricyclodecane skeleton, naphthylene ether type
  • examples include epoxy compounds and epoxy compounds having a triazine nucleus in their skeleton. Only one kind of the above-mentioned epoxy compound may be used, or two or more kinds thereof may be used in combination.
  • the epoxy compound is liquid or solid at room temperature (25°C), and when the epoxy compound is solid at room temperature, the melting temperature of the epoxy compound is preferably equal to or lower than the melting point of the solder particles.
  • the viscosity is high at the stage when the connection target members are bonded together, and when acceleration is applied due to impact such as transportation, the first connection target member and the second connection target member are bonded together. Misalignment with the target member can be suppressed.
  • the heat generated during curing can greatly reduce the viscosity of the conductive paste, allowing the solder particles to coagulate efficiently.
  • the epoxy compound preferably includes a phenol novolac type epoxy compound or a bisphenol F type epoxy compound.
  • the content of the thermosetting component in 100% by weight of the conductive paste is preferably 10% by weight or more, more preferably 15% by weight or more, even more preferably 20% by weight or more, and preferably 90% by weight or less, more preferably It is preferably 85% by weight or less, more preferably 80% by weight or less, particularly preferably 75% by weight or less.
  • the content of the thermosetting component is not less than the lower limit and not more than the upper limit, the solder particles can be arranged on the electrodes even more efficiently, and the insulation reliability between the electrodes can be further improved. This makes it possible to further improve the reliability of conduction between the electrodes. From the viewpoint of effectively increasing impact resistance, it is preferable that the content of the thermosetting component be as large as possible.
  • the content of the thermosetting compound in 100% by weight of the conductive paste is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, and preferably 90% by weight or less, more preferably It is preferably 85% by weight or less, more preferably 80% by weight or less, particularly preferably 75% by weight or less.
  • the content of the thermosetting compound is not less than the lower limit and not more than the upper limit, the solder particles can be arranged on the electrodes even more efficiently, and the insulation reliability between the electrodes can be further improved. This makes it possible to further improve the reliability of conduction between the electrodes. From the viewpoint of effectively increasing impact resistance, it is preferable that the content of the thermosetting compound be as large as possible.
  • the content of the epoxy compound in 100% by weight of the conductive paste is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, and preferably 90% by weight or less, more preferably It is 85% by weight or less, more preferably 80% by weight or less, particularly preferably 75% by weight or less.
  • the content of the epoxy compound is not less than the lower limit and not more than the upper limit, the solder particles can be arranged on the electrodes even more efficiently, and the insulation reliability between the electrodes can be further improved. The reliability of conduction between the electrodes can be further improved. From the viewpoint of effectively increasing impact resistance, it is preferable that the content of the epoxy compound is as large as possible.
  • thermosetting component thermosetting agent
  • the above thermosetting agent is not particularly limited.
  • the thermosetting agent thermosets the thermosetting compound.
  • examples of the above-mentioned thermosetting agents include thiol curing agents such as imidazole curing agents, amine curing agents, phenol curing agents, and polythiol curing agents, acid anhydride curing agents, thermal cationic initiators (thermal cationic curing agents), thermal radical generators, etc. can be mentioned.
  • the above thermosetting agents may be used alone or in combination of two or more.
  • the thermosetting agent is preferably an imidazole curing agent, a thiol curing agent, or an amine curing agent. Further, from the viewpoint of improving the storage stability when the thermosetting compound and the thermosetting agent are mixed, the thermosetting agent is preferably a latent curing agent.
  • the latent curing agent is a latent imidazole curing agent, a latent thiol curing agent or a latent amine curing agent.
  • the thermosetting agent may be coated with a polymeric substance such as polyurethane resin or polyester resin.
  • the above imidazole curing agent is not particularly limited.
  • Examples of the imidazole curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6 -[2'-Methylimidazolyl-(1')]-ethyl-s-triazine and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid addition 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2-paratolyl-4-methyl- 5 of 1H-imidazole in 5-hydroxymethylimidazole, 2-metato
  • the above thiol curing agent is not particularly limited.
  • examples of the thiol curing agent include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate.
  • the above amine curing agent is not particularly limited.
  • examples of the amine curing agent include hexamethylene diamine, octamethylene diamine, decamethylene diamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro[5.5]undecane, bis(4 -aminocyclohexyl)methane, metaphenylenediamine, and diaminodiphenylsulfone.
  • the acid anhydride curing agent mentioned above is not particularly limited.
  • acid anhydride curing agent acid anhydrides used as curing agents for thermosetting compounds such as epoxy compounds can be widely used.
  • the acid anhydride curing agents include phthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride.
  • anhydrides of phthalic acid derivatives maleic anhydride, nadic anhydride, methyl nadic anhydride, glutaric anhydride, succinic anhydride, glycerin bis-trimellitic anhydride monoacetate, and difunctional compounds such as ethylene glycol bis-trimellitic anhydride.
  • trifunctional acid anhydride curing agents such as trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, methylcyclohexenetetracarboxylic anhydride, polyazelaic anhydride, etc. Examples include acid anhydride curing agents having four or more functional groups.
  • thermal cationic initiator is not particularly limited.
  • thermal cationic initiator include iodonium-based cationic curing agents, oxonium-based cationic curing agents, and sulfonium-based cationic curing agents.
  • examples of the iodonium-based cationic curing agent include bis(4-tert-butylphenyl)iodonium hexafluorophosphate.
  • Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate.
  • the sulfonium-based cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.
  • thermal radical generator described above is not particularly limited.
  • examples of the thermal radical generator include azo compounds and organic peroxides.
  • examples of the azo compound include azobisisobutyronitrile (AIBN) and the like.
  • examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.
  • the reaction initiation temperature of the thermosetting agent is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 70°C or higher, preferably 250°C or lower, more preferably 200°C or lower, and even more preferably 175°C.
  • the temperature below is particularly preferably 150°C or below.
  • the reaction start temperature of the thermosetting agent is equal to or higher than the lower limit and lower than the upper limit, solder particles can be arranged on the electrode even more efficiently. It is particularly preferable that the reaction initiation temperature of the thermosetting agent is 70°C or more and 150°C or less.
  • the reaction start temperature of the thermosetting agent means the temperature at which the exothermic peak starts to rise in differential scanning calorimetry (DSC).
  • the content of the thermosetting agent is not particularly limited. With respect to 100 parts by weight of the thermosetting compound, the content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, and preferably 200 parts by weight or less, more preferably The amount is 100 parts by weight or less, more preferably 75 parts by weight or less.
  • the content of the thermosetting agent is equal to or higher than the lower limit, it is easy to sufficiently cure the conductive paste.
  • the content of the thermosetting agent is below the above upper limit, it becomes difficult for excess thermosetting agent that did not take part in curing to remain after curing, and the heat resistance of the cured product becomes even higher.
  • solder particles Both the center portion and the outer surface of the solder particles are made of solder.
  • the solder particles described above are particles in which both the center portion and the outer surface are solder.
  • conductive particles comprising base particles made of a material other than solder and a solder portion disposed on the surface of the base particles are used instead of the solder particles described above, conductive particles can be placed on the electrodes. Particles become difficult to collect.
  • the conductive particles described above have low solder bondability between conductive particles, the conductive particles that have moved onto the electrode tend to move out of the electrode, and the effect of suppressing misalignment between the electrodes is also low. tends to be lower.
  • the average particle diameter of the solder particles is 5.0 ⁇ m or less.
  • the average particle diameter of the solder particles is preferably 0.1 ⁇ m or more, more preferably 0.5 ⁇ m or more, even more preferably 1.0 ⁇ m or more, and preferably 4.9 ⁇ m or less, more preferably 4.5 ⁇ m or less, and Preferably it is 4.0 ⁇ m or less.
  • the average particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be arranged on the electrode much more efficiently.
  • the average particle diameter of the solder particles is equal to or less than the above upper limit, screen printing properties on fine-pitch substrates and the like can be further improved.
  • the smaller the average particle diameter of the solder particles the more effectively the above effects of the present invention are exhibited. That is, in the conductive paste according to the present invention, the smaller the average particle diameter of the solder particles, the more efficiently the solder particles can be arranged on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected is improved. can effectively increase the insulation reliability between adjacent horizontal electrodes that should not be connected.
  • the average particle diameter of the solder particles is preferably a number average particle diameter.
  • the average particle diameter of the above solder particles can be determined, for example, by observing 50 arbitrary solder particles with an electron microscope or optical microscope and calculating the average value of the particle diameter of each solder particle, or by laser diffraction particle size distribution measurement. It is sought after by doing. In observation using an electron microscope or an optical microscope, the particle diameter of each solder particle is determined as the particle diameter in equivalent circle diameter. In observation using an electron microscope or an optical microscope, the average particle diameter of any 50 solder particles in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. In the laser diffraction particle size distribution measurement, the particle diameter of each solder particle is determined as the particle diameter in equivalent sphere diameter.
  • the average particle diameter of the solder particles is preferably calculated by laser diffraction particle size distribution measurement.
  • the coefficient of variation (CV value) of the particle diameter of the solder particles is preferably 5% or more, more preferably 10% or more, and preferably 40% or less, more preferably 30% or less.
  • the coefficient of variation of the particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be arranged on the electrodes even more efficiently.
  • the CV value of the particle diameter of the solder particles may be less than 5%.
  • CV value The above coefficient of variation (CV value) can be measured as follows.
  • CV value (%) ( ⁇ /Dn) x 100 ⁇ : Standard deviation of particle diameter of solder particles Dn: Average value of particle diameter of solder particles
  • the shape of the solder particles is not particularly limited.
  • the shape of the solder particles may be spherical, a shape other than spherical, or a flat shape.
  • the specific gravity of the solder particles is preferably 4 or more, more preferably 5 or more, and still more preferably 6 or more.
  • the specific gravity of the solder particles is determined using, for example, "Accupic II 1340" manufactured by Shimadzu Corporation.
  • the solder is preferably a metal whose melting point is 450° C. or lower (low melting point metal).
  • the solder particles are preferably metal particles having a melting point of 450° C. or lower (low-melting point metal particles).
  • the low melting point metal particles are particles containing a low melting point metal.
  • the low melting point metal refers to a metal having a melting point of 450° C. or lower.
  • the melting point of the low melting point metal is preferably 300°C or lower, more preferably 260°C or lower.
  • the solder is preferably a low melting point solder having a melting point of less than 250°C.
  • the melting point of the solder particles is preferably 100°C or higher, more preferably 150°C or higher, even more preferably 200°C or higher, and preferably 400°C or lower, more preferably 350°C or higher.
  • the temperature is preferably 300°C or lower, more preferably 300°C or lower.
  • the melting point of the solder particles can be determined by differential scanning calorimetry (DSC).
  • DSC differential scanning calorimetry
  • Examples of the differential scanning calorimetry (DSC) device include "EXSTAR DSC7020" manufactured by SII.
  • the solder particles contain tin.
  • the content of tin in 100% by weight of metal contained in the solder particles is preferably 30% by weight or more, more preferably 40% by weight or more, further preferably 70% by weight or more, and particularly preferably 90% by weight or more. .
  • the content of tin in the solder particles is equal to or higher than the lower limit, the conduction reliability and connection reliability between the solder portion and the electrode will be further increased.
  • the above tin content is based on a high-frequency inductively coupled plasma emission spectrometer (for example, "ICP-AES” manufactured by Horiba) or a fluorescent X-ray analyzer (for example, "EDX-800HS” manufactured by Shimadzu Corporation). It can be measured using, etc.
  • a high-frequency inductively coupled plasma emission spectrometer for example, "ICP-AES” manufactured by Horiba
  • EDX-800HS fluorescent X-ray analyzer
  • solder particles melts and joins to the electrodes, and the solder portion establishes conduction between the electrodes. For example, since the solder portion and the electrode tend to make surface contact rather than point contact, the connection resistance becomes low. Furthermore, the use of the solder particles increases the bonding strength between the solder part and the electrode, making it even more difficult for the solder part to separate from the electrode, resulting in even higher conduction reliability and connection reliability.
  • the low melting point metal that constitutes the solder particles is not particularly limited.
  • the low melting point metal is preferably tin or an alloy containing tin.
  • the alloy include tin-silver alloy, tin-copper alloy, tin-silver-copper alloy, tin-bismuth alloy, tin-zinc alloy, tin-indium alloy, and tin-antimony alloy.
  • the low melting point metal is preferably tin, tin-silver alloy, tin-silver-copper alloy, tin-bismuth alloy, tin-indium alloy, or tin-antimony alloy, since it has excellent wettability to the electrode. More preferably, it is a tin-silver-copper alloy, a tin-bismuth alloy, a tin-indium alloy, or a tin-antimony alloy.
  • the solder particles are preferably filler metals whose liquidus line is 450° C. or less based on JIS Z3001: Welding terminology.
  • the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium, and the like. Preferred are tin-indium (117° C. eutectic) or tin-bismuth (139° C. eutectic) which have a low melting point and are lead-free. That is, the solder particles preferably do not contain lead, and preferably contain tin and indium, or tin and bismuth.
  • the solder particles include nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, It may also contain metals such as molybdenum and palladium. Moreover, from the viewpoint of further increasing the bonding strength between the solder part and the electrode, it is preferable that the solder particles contain nickel, copper, antimony, aluminum, or zinc.
  • the content of these metals for increasing the bonding strength is preferably 0.0001% by weight or more based on 100% by weight of the metal contained in the solder particles, Preferably it is 1% by weight or less.
  • the content of the solder particles in 100% by weight of the conductive paste is preferably 50% by weight or more, more preferably 55% by weight or more, further preferably 60% by weight or more, particularly preferably 65% by weight or more, and most preferably It is 70% by weight or more.
  • the content of the solder particles in 100% by weight of the conductive paste is preferably 90% by weight or less, more preferably 85% by weight or less, still more preferably 80% by weight or less, particularly preferably 75% by weight or less.
  • the content of the solder particles is not less than the lower limit and not more than the upper limit, the solder particles can be arranged on the electrodes even more efficiently, and it is easy to arrange a large amount of solder between the electrodes, Continuity reliability becomes even higher. From the viewpoint of further improving conduction reliability, it is preferable that the content of the solder particles is large.
  • the conductive paste according to the present invention contains flux.
  • the above flux is solid at 25°C.
  • the flux (flux alone) is solid at 25° C. without being mixed with the thermosetting component, the plurality of solder particles, and the thixotropic agent.
  • the flux is preferably solid in the conductive paste at 25°C. In the conductive paste, the flux is preferably present in solid form in the conductive paste at 25°C.
  • a flux that is solid at 25°C is defined as a flux that maintains its shape when the flux alone is allowed to stand for 5 minutes at 25°C and 50% RH.
  • a flux that does not maintain its shape when the flux alone is allowed to stand for 5 minutes at 25°C and 50% RH is defined as a semi-solid flux at 25°C.
  • a flux that is semi-solid at 25°C is not included in a flux that is solid at 25°C.
  • a flux that is solid at 25°C is defined as a flux that maintains its shape when a conductive paste containing the flux is left to stand for 5 minutes at 25°C and 50% RH. . Further, a flux that does not maintain its shape when a conductive paste containing flux is left to stand for 5 minutes at 25° C. and 50% RH is defined as a semi-solid flux at 25° C. Further, a flux that is semi-solid at 25°C is not included in a flux that is solid at 25°C.
  • the above fluxes include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, an organic phosphorus compound, an organic halide, hydrazine, an amine compound, an organic acid, and a salt of an organic acid. , and pine resin.
  • the above fluxes may be used alone or in combination of two or more.
  • Examples of the molten salt include ammonium chloride.
  • organic phosphorus compounds examples include organic phosphonium salts, organic phosphoric acids, organic phosphoric esters, organic phosphonic acids, organic phosphonic esters, organic phosphinic acids, and organic phosphinic esters.
  • Examples of the above amine compounds include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzimidazole, benzotriazole, and carboxybenzotriazole.
  • the above-mentioned pine resin is a rosin whose main component is abietic acid.
  • the rosins include abietic acid and acrylic modified rosin.
  • Examples of the above-mentioned salts of organic acids include neutralization reaction products (salts) of organic acids and basic compounds.
  • the above organic acid salt is preferably a salt produced by a neutralization reaction between an organic acid and a basic compound.
  • the conditions for the neutralization reaction are preferably a heating temperature of 25° C. to 150° C. and a heating time of 5 minutes to 30 minutes.
  • the organic acid preferably has the effect of cleaning the surface of the metal, and the basic compound preferably has the effect of neutralizing the organic acid.
  • the organic acid is preferably an organic compound having a carboxyl group (carboxylic acid).
  • the organic acids include aliphatic carboxylic acids, alicyclic carboxylic acids, and aromatic carboxylic acids.
  • Examples of the aliphatic carboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, and malic acid.
  • Examples of the alicyclic carboxylic acid include cyclohexylcarboxylic acid and 1,4-cyclohexyldicarboxylic acid.
  • the aromatic carboxylic acids include isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid.
  • the organic acid may be glutaric acid, cyclohexylcarboxylic acid, or adipic acid. It is preferable that there be.
  • the basic compound is preferably an organic compound having an amino group (amine compound).
  • the above basic compounds include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, 4-tert-butylbenzylamine. , N-methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N,N-dimethylbenzylamine, imidazole compounds, and triazole compounds. . From the viewpoint of more efficiently arranging solder particles on the electrode, improving insulation reliability, and even more effectively improving continuity reliability, the basic compound is preferably benzylamine.
  • Examples of the salts of the organic acids include adipic acid benzylamine salt, glutaric acid benzylamine salt, and succinic acid cyclohexylamine salt.
  • the flux is preferably a salt of an organic acid, and is preferably an adipic acid benzylamine salt. is particularly preferred.
  • the above flux may be dispersed in the conductive paste or may be attached to the surface of the solder particles.
  • the shape of the above flux is not particularly limited.
  • the above-mentioned flux may be spherical, may have a shape other than spherical, or may have a flat shape or the like. From the viewpoint of further improving screen printability, the shape of the flux is preferably spherical.
  • the particle size of the flux is preferably 0.1 ⁇ m or more, more preferably 0.5 ⁇ m or more, even more preferably 1.0 ⁇ m or more, and preferably 30 ⁇ m or less, more preferably 25 ⁇ m or less, and still more preferably 20 ⁇ m or less. .
  • the particle size of the flux is preferably an average particle size, and more preferably a number average particle size.
  • the average particle diameter of the above flux can be determined by, for example, observing 50 arbitrary fluxes with an electron microscope or optical microscope and calculating the average value of the particle diameter of each flux, or by performing laser diffraction particle size distribution measurement. Desired. In observation using an electron microscope or an optical microscope, the particle diameter of each flux is determined as the particle diameter in equivalent circle diameter. In observation using an electron microscope or an optical microscope, the average particle diameter of any 50 fluxes in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. In the laser diffraction particle size distribution measurement, the particle diameter of each flux is determined as the particle diameter in equivalent sphere diameter. The average particle diameter of the flux is preferably calculated by laser diffraction particle size distribution measurement.
  • the ratio of the average particle diameter of the flux to the average particle diameter of the solder particles is preferably 0.01 or more, more preferably 0.1 or more, and even more preferably is 0.2 or more, preferably 15.0 or less, more preferably 10.0 or less, even more preferably 5.0 or less.
  • the above ratio average particle diameter of flux/average particle diameter of solder particles
  • the flux can be brought into effective contact with the solder particles, and the flux performance during heating can be improved. It can be further improved.
  • the above-mentioned flux preferably does not have water absorbency, and preferably does not have hygroscopicity.
  • the weight of the flux When the flux is left at 25° C. and 50% RH for 24 hours, the weight of the flux may increase, decrease, or remain unchanged. When the flux is left for 24 hours at 25° C. and 50% RH, the weight of the flux after being left may be greater or less than the weight of the flux before being left. When the flux is left for 24 hours at 25° C. and 50% RH, the weight of the flux after being left may be the same as the weight of the flux before being left.
  • the following weight change rate F when the above flux is left at 25°C and 50% RH for 24 hours is preferably less than 1% by weight, more preferably is 0.9% by weight or less, more preferably 0.5% by weight or less.
  • the weight change rate F may be 0% by weight or more, or 0.1% by weight or more. From the viewpoint of exhibiting the effects of the present invention even more effectively, the weight change rate F is most preferably 0% by weight (no weight change before and after standing).
  • Weight change rate F (weight%)
  • the weight change rate F of the above flux can be measured by the following method. Take out 10 g (W3) of flux from a desiccator at 25° C. and 0% RH, and leave it for 24 hours at 25° C. and 50% RH. The weight (W4) of the flux after being left is measured. The weight change rate F is determined from W3 and W4.
  • the melting point (activation temperature) of the flux is preferably 50°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C. It is as follows. When the melting point of the above-mentioned flux is above the above-mentioned lower limit and below the above-mentioned upper limit, solder particles can be arranged on the electrode even more efficiently.
  • the melting point of the above flux can be determined by differential scanning calorimetry (DSC).
  • DSC differential scanning calorimetry
  • Examples of the differential scanning calorimetry (DSC) device include "EXSTAR DSC7020" manufactured by SII.
  • the content of the flux in 100% by weight of the conductive paste is preferably 1% by weight or more, more preferably 5% by weight or more, and preferably 30% by weight or less, more preferably 25% by weight or less.
  • the content of the flux is above the above lower limit and below the above upper limit, it becomes even more difficult to form an oxide film on the surfaces of the solder particles and electrodes, and furthermore, the oxide film formed on the surfaces of the solder particles and electrodes becomes more difficult to form. It can be removed even more effectively.
  • the content of the flux is preferably 1 part by weight or more, more preferably 5 parts by weight or more, and preferably 30 parts by weight or less, more preferably 25 parts by weight or less. It is.
  • the content of the flux is above the above lower limit and below the above upper limit, it becomes even more difficult to form an oxide film on the surfaces of the solder particles and electrodes, and furthermore, the oxide film formed on the surfaces of the solder particles and electrodes becomes more difficult to form. It can be removed even more effectively.
  • the content of the flux is preferably 1 part by weight or more, more preferably 5 parts by weight or more, and preferably 30 parts by weight or less, more preferably 25 parts by weight or less.
  • the content of the flux is above the above lower limit and below the above upper limit, it becomes even more difficult to form an oxide film on the surfaces of the solder particles and electrodes, and furthermore, the oxide film formed on the surfaces of the solder particles and electrodes becomes more difficult to form. It can be removed even more effectively.
  • the conductive paste according to the present invention contains a thixotropic agent.
  • the thixotropic agent is (A) a thixotropic agent that is a liquid at 25°C and has a hydroxyl group, or (B) a thixotropic agent that is a solid at 25°C and the thixotropic agent is 50%
  • the thixotropic agent has the following weight increase rate of 0.2% by weight or more when left at RH for 24 hours.
  • Weight increase rate (weight%) (W2-W1) x 100/W1
  • W1 Weight of the above thixotropic agent before standing
  • W2 Weight of the above thixotropic agent after standing
  • the above-mentioned thixotropic agent may be (A) a thixotropic agent that is liquid at 25° C. and has a hydroxyl group (hereinafter sometimes referred to as "thixotropic agent A"). Further, the above-mentioned thixotropic agent is (B) a thixotropic agent that is solid at 25°C and has the above-mentioned weight increase rate of 0.2% by weight or more (hereinafter sometimes referred to as "thixotropic agent B”) It may be.
  • the thixotropic agent is the thixotropic agent A or the thixotropic agent B.
  • the thixotropic agent is the thixotropic agent A or the thixotropic agent B, the flux performance can be favorably assisted and the solder particles can be arranged on the electrode more efficiently.
  • the content of the thixotropic agent in 100% by weight of the conductive paste is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, even more preferably 0.05% by weight or more, and preferably It is 2% by weight or less, more preferably 1% by weight or less, even more preferably 0.5% by weight or less.
  • the content of the thixotropic agent is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the content of the thixotropic agent is preferably 0.003 parts by weight or more, more preferably 0.005 parts by weight or more, even more preferably 0.01 parts by weight or more, The amount is preferably 2 parts by weight or less, more preferably 1 part by weight or less, and still more preferably 0.7 parts by weight or less.
  • the content of the thixotropic agent is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the content of the thixotropic agent is preferably 0.1 parts by weight or more, more preferably 0.3 parts by weight or more, and preferably 5 parts by weight or less, based on 100 parts by weight of the thermosetting component. Preferably it is 3 parts by weight or less.
  • the content of the thixotropic agent is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the content of the thixotropic agent is preferably 0.1 parts by weight or more, more preferably 0.3 parts by weight or more, and preferably 5 parts by weight or less, based on 100 parts by weight of the thermosetting compound. Preferably it is 3 parts by weight or less.
  • the content of the thixotropic agent is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the thixotropic agent A is liquid at 25° C. and has a hydroxyl group (—OH group).
  • the above thixotropic agent A is a liquid at 25°C.
  • the thixotropic agent A (thixotropic agent A alone) is a liquid at 25° C. without being mixed with the thermosetting component, the plurality of solder particles, and the flux.
  • the thixotropic agent A is preferably a liquid in the conductive paste at 25°C. In the conductive paste, the thixotropic agent A is preferably present in liquid form in the conductive paste at 25°C.
  • the thixotropic agent A has at least one hydroxyl group.
  • the thixotropic agent A may have one hydroxyl group, two hydroxyl groups, two or more hydroxyl groups, three or more hydroxyl groups, or three or more hydroxyl groups. or four or more.
  • the thixotropic agent A may be a monohydric alcohol or a polyhydric alcohol.
  • the thixotropic agent A may be a dihydric alcohol, a trihydric alcohol, or a tetrahydric alcohol. From the viewpoint of preventing volatilization of the conductive paste and further improving screen printability, the thixotropic agent A preferably has two or more hydroxyl groups, more preferably three or more.
  • the thixotropic agent A is preferably a polyol compound (polyhydric alcohol).
  • the thixotropic agent A may have 10 or less hydroxyl groups, or may have 7 or less hydroxyl groups.
  • examples of thixotropic agents having one hydroxyl group include methanol, ethanol, propanol, and N-oleoylsarcosine.
  • examples of thixotropic agents having two hydroxyl groups include propylene glycol, propanediol, and diethylene glycol.
  • examples of thixotropic agents having three hydroxyl groups include glycerol (glycerin), trimethylolpropane, and 1,2,4-butanetriol.
  • examples of thixotropic agents having four or more hydroxyl groups include diglycerin, polyglycerin, and the like.
  • the thixotropic agent A is preferably glycerol (glycerin), N-oleoylsarcosine, or 1,2,4-butanetriol. , glycerol (glycerin) is more preferred.
  • the boiling point of the thixotropic agent A is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 150°C or higher, particularly preferably 200°C or higher.
  • the temperature is preferably 450°C or lower, more preferably 400°C or lower, and even more preferably 350°C or lower.
  • the thixotropic agent A is (A1) a thixotropic agent that is liquid at 25°C, has a hydroxyl group, and has a boiling point of 80°C or higher.
  • it is an agent.
  • the content of the thixotropic agent A in 100% by weight of the conductive paste is preferably 0.001% by weight or more, more preferably 0.005% by weight or more, still more preferably 0.05% by weight or more, and preferably is 2% by weight or less, more preferably 1% by weight or less, even more preferably 0.5% by weight or less.
  • the content of the thixotropic agent A is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the content of the thixotropic agent A is preferably 0.003 parts by weight or more, more preferably 0.005 parts by weight or more, and still more preferably 0.01 parts by weight or more. , preferably 2 parts by weight or less, more preferably 1 part by weight or less, still more preferably 0.7 parts by weight or less.
  • the content of the thixotropic agent A is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the thixotropic agent B is solid at 25° C., and has the following weight increase rate of 0.2% by weight or more when the thixotropic agent is left at 25° C. and 50% RH for 24 hours.
  • Weight increase rate (weight%) (W2-W1) x 100/W1
  • W1 Weight of the above thixotropic agent before standing
  • W2 Weight of the above thixotropic agent after standing
  • the above thixotropic agent B is solid at 25°C. Specifically, the thixotropic agent B (thixotropic agent B alone) is solid at 25° C. without being mixed with the thermosetting component, the plurality of solder particles, and the flux.
  • the thixotropic agent B is preferably solid in the conductive paste at 25°C. In the conductive paste, the thixotropic agent B is preferably present in solid form in the conductive paste at 25°C.
  • thixotropic agent B thixotropic agent B alone
  • thixotropic agent B that maintains its shape when thixotropic agent B alone is left standing for 5 minutes at 25°C and 50% RH
  • thixotropic agent B that is not liquid at 25°C.
  • solid thixotropic agent B thixotropic agent B that does not maintain its shape when thixotropic agent B alone is allowed to stand for 5 minutes at 25° C. and 50% RH is defined as thixotropic agent B that is semisolid at 25° C.
  • thixotropic agent B which is semi-solid at 25°C, is not included in thixotropic agent B, which is solid at 25°C.
  • thixotropic agent B is solid in the conductive paste at 25° C.
  • Thixotropic agent B is defined as solid at 25°C.
  • thixotropic agent B that does not retain its shape when a conductive paste containing thixotropic agent B is allowed to stand for 5 minutes at 25° C. and 50% RH is defined as thixotropic agent B that is semi-solid at 25° C.
  • thixotropic agent B which is semi-solid at 25°C, is not included in thixotropic agent B, which is solid at 25°C.
  • the above thixotropic agent B increases in weight when left for 24 hours at 25° C. and 50% RH.
  • the weight of the thixotropic agent B after being left is greater than the weight of the thixotropic agent B before being left.
  • the thixotropic agent B preferably has water absorption or hygroscopicity, and more preferably has hygroscopicity. preferable. From the viewpoint of favorably assisting flux performance and arranging solder particles on the electrode more efficiently, it is more preferable that the thixotropic agent B has hygroscopicity at 25° C. and 50% RH.
  • the weight increase rate of the thixotropic agent B is 0.2% by weight or more.
  • the weight increase rate of the thixotropic agent B is preferably 0.3% by weight or more, more preferably 0.5% by weight or more, even more preferably 1% by weight or more, and preferably less than 10% by weight, more preferably is 8% by weight or less, more preferably 5% by weight or less.
  • the weight increase rate of the thixotropic agent B is equal to or higher than the lower limit, the flux performance can be favorably assisted and the solder particles can be arranged on the electrode more efficiently.
  • the weight increase rate of the thixotropic agent B is below the above upper limit or below the above upper limit, screen printability can be further improved.
  • the thixotropic agent B is solid at 25° C. and has a weight increase rate of 1% by weight or more. Particularly preferred are certain thixotropic agents.
  • the weight increase rate of the thixotropic agent B can be measured by the following method. Take out 10 g (W1) of thixotropic agent B from a desiccator at 25° C. and 0% RH, and leave it for 24 hours at 25° C. and 50% RH. The weight (W2) of thixotropic agent B after standing is measured.
  • thixotropic agent B examples include boron trifluoride-monoethylamine complex, pentaerythritol, sorbitol, mannitol, sorbitan, dipentaerythritol, sucrose, glucose, mannose, fructose, and methyl glucoside.
  • the thixotropic agent B is preferably a boron trifluoride-monoethylamine complex or glucose, and a boron trifluoride-monoethylamine complex. It is more preferable that there be.
  • the shape of the thixotropic agent B is not particularly limited.
  • the thixotropic agent B may be spherical, may have a shape other than spherical, or may have a flat shape or the like. From the viewpoint of further improving screen printability, the shape of the thixotropic agent B is preferably spherical.
  • the particle size of the thixotropic agent B is preferably 0.1 ⁇ m or more, more preferably 0.5 ⁇ m or more, even more preferably 1 ⁇ m or more, and preferably 30 ⁇ m or less, more preferably 25 ⁇ m or less, and still more preferably 20 ⁇ m or less. be.
  • the particle size of the thixotropic agent B is preferably an average particle size, more preferably a number average particle size.
  • the average particle diameter of the thixotropic agent B can be determined, for example, by observing 50 arbitrary thixotropic agents B with an electron microscope or an optical microscope and calculating the average value of the particle diameter of each thixotropic agent B, or by laser diffraction analysis. It is determined by formula particle size distribution measurement. In observation using an electron microscope or an optical microscope, the particle size of each thixotropic agent B is determined as the particle size in equivalent circle diameter. In observation using an electron microscope or an optical microscope, the average particle diameter of any 50 thixotropic agents B in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter.
  • the particle size of each thixotropic agent B is determined as the particle size in equivalent sphere diameter.
  • the average particle diameter of the thixotropic agent B is preferably calculated by laser diffraction particle size distribution measurement.
  • the melting point (activation temperature) of the thixotropic agent B is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 70°C or higher, and preferably 140°C or lower, more preferably 120°C or lower, even more preferably is below 100°C.
  • the melting point of the thixotropic agent B is not less than the above lower limit and not more than the above upper limit, solder particles can be arranged on the electrode even more efficiently.
  • the melting point of the thixotropic agent B can be determined by differential scanning calorimetry (DSC).
  • DSC differential scanning calorimetry
  • Examples of the differential scanning calorimetry (DSC) device include "EXSTAR DSC7020" manufactured by SII.
  • the melting point of the thixotropic agent B is preferably lower than the melting point of the solder particles. From the viewpoint of arranging the solder particles on the electrode more efficiently, the melting point of the thixotropic agent B is more preferably 5° C. or more lower than the melting point of the solder particles, and more preferably 10° C. or more lower. preferable.
  • the content of the thixotropic agent B in 100% by weight of the conductive paste is preferably 0.001% by weight or more, more preferably 0.005% by weight or more, and preferably 2% by weight or less, more preferably 1% by weight or more. It is not more than 0.5% by weight, more preferably not more than 0.5% by weight.
  • the content of the thixotropic agent B is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the content of the thixotropic agent B is preferably 0.005 parts by weight or more, more preferably 0.01 parts by weight or more, and preferably 2 parts by weight or less, more preferably is 1 part by weight or less, more preferably 0.7 part by weight or less.
  • the content of the thixotropic agent B is not less than the above lower limit and not more than the above upper limit, flux performance can be favorably assisted and solder particles can be arranged on the electrode more efficiently.
  • the above conductive paste may contain, as necessary, fillers, extenders, softeners, plasticizers, leveling agents, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, etc. It may contain various additives such as additives, lubricants, antistatic agents, and flame retardants.
  • connection structure includes a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and the first connection target member, and a connecting portion connecting the second connection target member.
  • the material of the connection portion is the conductive paste described above.
  • the first electrode and the second electrode are electrically connected by a solder part in the connecting part.
  • the thickness of the solder portion between the electrodes is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more, and preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less.
  • the solder wetted area on the surface of the electrode is preferably 50% or more, more preferably 70% or more, and preferably 100% or less.
  • the method for manufacturing the above-mentioned connected structure is not particularly limited.
  • An example of a method for manufacturing a connected structure includes a method in which the conductive paste is placed between a first member to be connected and a second member to be connected, a laminate is obtained, and then the laminate is heated.
  • the heating temperature is preferably 230°C or higher, more preferably 250°C or higher, and preferably 350°C or lower, more preferably 300°C or lower.
  • the heating temperature is equal to or higher than the lower limit and lower than the upper limit, the reliability of conduction and insulation between the electrodes can be further improved.
  • pressurization may or may not be applied.
  • FIG. 1 is a cross-sectional view schematically showing a connected structure obtained using a conductive paste according to an embodiment of the present invention.
  • the connection structure 1 shown in FIG. 1 includes a first connection target member 2, a second connection target member 3, and a connection connecting the first connection target member 2 and the second connection target member 3. 4.
  • the connecting portion 4 is formed of the above-mentioned conductive paste.
  • the conductive paste includes a thermosetting component, solder particles, flux, and a thixotropic agent.
  • the thermosetting component includes a thermosetting compound and a thermosetting agent.
  • the thixotropic agent is the thixotropic agent A or the thixotropic agent B.
  • the connecting portion 4 includes a solder portion 4A in which a plurality of solder particles are gathered and bonded to each other, and a cured material portion 4B in which a thermosetting compound is thermoset.
  • the first connection target member 2 has a plurality of first electrodes 2a on its surface (upper surface).
  • the second connection target member 3 has a plurality of second electrodes 3a on the front surface (lower surface).
  • the first electrode 2a and the second electrode 3a are electrically connected by a solder portion 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by the solder portion 4A.
  • no solder particles are present in a region different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a (cured material portion 4B portion). In a region different from the solder portion 4A (cured material portion 4B portion), there are no solder particles separated from the solder portion 4A.
  • solder particles may be present in a region different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a (cured material portion 4B portion) as long as the amount is small.
  • connection structure 1 a plurality of solder particles gather between a first electrode 2a and a second electrode 3a, and after the plurality of solder particles are melted, a melted solder particle is formed.
  • the solder portion 4A is formed by wetting and spreading the surface of the electrode and solidifying the solder portion 4A. Therefore, the contact area between the solder portion 4A and the first electrode 2a and between the solder portion 4A and the second electrode 3a becomes large. That is, by using solder particles, the solder portion 4A and the first electrode 2a, as well as the solder portion 4A and the The contact area with the second electrode 3a becomes larger. This also increases the conduction reliability and connection reliability in the connection structure 1. Note that the above-mentioned flux is generally gradually deactivated by heating.
  • connection structure 1 when looking at the portion where the first electrode 2a and the second electrode 3a face each other in the stacking direction of the first electrode 2a, the connection portion 4, and the second electrode 3a, the first It is preferable that the solder portion 4A in the connecting portion 4 is disposed on 50% or more of the 100% area of the opposing portion of the electrode 2a and the second electrode 3a.
  • the solder portion 4A in the connection portion 4 satisfies the above-mentioned preferable aspects, the continuity reliability can be further improved.
  • the solder portion in the connection portion is disposed on 50% or more of the 100% area of the portion facing the second electrode.
  • the solder portion in the connection portion is disposed on 60% or more of the 100% area of the portion facing the second electrode.
  • the solder part in the connection part is disposed on 70% or more of the 100% area of the part facing the second electrode.
  • the solder portion in the connection portion is disposed on 80% or more of the 100% area of the portion facing the second electrode.
  • the solder part in the connection part is disposed on 90% or more of the 100% area of the part facing the second electrode.
  • the first It is preferable that 60% or more of the solder portion in the connection portion is disposed at the portion where the electrode and the second electrode face each other.
  • the first More preferably, 70% or more of the solder portion in the connection portion is disposed in a portion where the electrode and the second electrode face each other.
  • the first It is most preferable that 99% or more of the solder portion in the connecting portion is disposed at the portion where the electrode and the second electrode face each other.
  • the solder portion in the connection portion satisfies the preferred embodiments described above, conduction reliability can be further improved.
  • the first and second connection target members are not particularly limited.
  • the first and second connection target members include semiconductor chips, semiconductor packages, LED chips, LED packages, electronic components such as capacitors and diodes, resin films, printed circuit boards, flexible printed circuit boards, and flexible Examples include electronic components such as flat cables, rigid-flexible boards, circuit boards such as glass epoxy boards, and glass boards. It is preferable that the first and second connection target members are electronic components.
  • At least one of the first connection target member and the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board.
  • the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board.
  • Resin films, flexible printed circuit boards, flexible flat cables, and rigid-flexible circuit boards have the properties of being highly flexible and relatively lightweight. When a conductive film is used to connect such connection target members, solder particles tend to be difficult to collect on the electrodes.
  • the electrodes provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes.
  • the electrode is preferably a gold electrode, a tin electrode, a silver electrode, or a copper electrode.
  • the electrode is preferably a copper electrode or a silver electrode.
  • the said electrode is an aluminum electrode, it may be an electrode formed only with aluminum, and the electrode may be an electrode in which an aluminum layer is laminated
  • 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 elements include Sn, Al, and Ga.
  • the first electrode and the second electrode are preferably arranged in an area array or peripheral.
  • the effects of the present invention are even more effectively exhibited when the first electrode and the second electrode are arranged in an area array or peripherally.
  • the above-mentioned area array is a structure in which electrodes are arranged in a grid pattern on the surface of the connection target member on which the electrodes are arranged.
  • the above-mentioned peripheral refers to a structure in which electrodes are arranged on the outer periphery of a member to be connected.
  • solder particles In the case of a structure in which the electrodes are arranged in a comb shape, the solder particles only need to aggregate along the direction perpendicular to the comb, whereas in the above area array or peripheral structure, the solder particles aggregate on the entire surface on the surface where the electrodes are arranged. It is necessary for the solder particles to coagulate uniformly. Therefore, in the conventional method, the amount of solder tends to be uneven, whereas in the method of the present invention, solder particles can be uniformly aggregated over the entire surface.
  • Thermosetting component (thermosetting compound): Phenol novolac type epoxy compound (“DEN431” manufactured by DOW) Bisphenol F type epoxy compound (“DER354” manufactured by DOW)
  • Solder particles Solder particles 1 (SnAgCu solder particles, "Sn96.5Ag3.0Cu0.5 ST-3" manufactured by Mitsui Kinzoku, average particle size: 3.0 ⁇ m, melting point: 219 ° C., specific gravity: 7.4) Solder particles 2 (SnBi solder particles, "Sn42Bi58 ST-3" manufactured by Mitsui Kinzoku, average particle diameter: 3.0 ⁇ m, melting point: 138 ° C., specific gravity: 8.6) Solder particles 3 (SnAgCu solder particles, "Sn96.5Ag3.0Cu0.5 DS10" manufactured by Mitsui Kinzoku, average particle diameter: 10.0 ⁇ m, melting point: 219 ° C., specific gravity: 7.4) Solder particles 4 (SnAgCu solder particles, "Sn96.5Ag3.0Cu0.5 ST-7" manufactured by Mitsui Kinzoku, average particle diameter: 7.0 ⁇ m, melting point: 219 ° C., specific gravity: 7.4)
  • Adipic acid benzylamine salt (“Adipate benzylamine salt” manufactured by Showa Kagaku Kogyo Co., Ltd., solid at 25°C, average particle size: 10 ⁇ m, melting point: 180°C)
  • Oleic acid Oleic acid manufactured by Fujifilm Wako Pure Chemical Industries, liquid at 25°C, boiling point: 223°C
  • Thixotropic agents Glycerol (“Glycerol” manufactured by Nacalai Tesque, liquid at 25°C, number of hydroxyl groups: 3, boiling point: 290°C) N-oleoylsarcosine (“N-oleoylsarcosine” manufactured by TCI, liquid at 25°C, number of hydroxyl groups: 1, boiling point: 197°C) Boron trifluoride-monoethylamine complex (“Boron trifluoride-monoethylamine complex” manufactured by TCI, solid at 25°C, hygroscopic at 25°C and 50% RH, melting point: 85°C) N,N'-ethylene bis(stearoamide) (Mitsubishi Chemical Corporation's "Slipax E", solid at 25°C, non-hygroscopic at 25°C and 50% RH (weight increase rate 0% by weight))
  • Examples 1 to 6 and Comparative Examples 1 to 4 (1) Preparation of conductive paste (anisotropic conductive paste) The components shown in Tables 1 to 3 below are mixed in the amounts shown in Tables 1 to 3 below to obtain a conductive paste (anisotropic conductive paste). Ta.
  • connection structure As the first connection target member, a glass epoxy substrate (material: FR- 4. Thickness: 0.6 mm) was prepared.
  • a flexible printed circuit board material: polyimide, thickness: 0.1 mm
  • copper electrodes electrode length: 3 mm, electrode thickness: 12 ⁇ m
  • L/S 50 ⁇ m/50 ⁇ m on the surface
  • a conductive paste (anisotropic conductive paste) immediately after preparation was applied to the upper surface of the glass epoxy substrate to a thickness of 100 ⁇ m to form a conductive paste (anisotropic conductive paste) layer.
  • a flexible printed circuit board was laminated on the upper surface of the conductive paste (anisotropic conductive paste) layer so that the electrodes faced each other.
  • the weight of the flexible printed circuit board is added to the conductive paste (anisotropic conductive paste) layer. From this state, the conductive paste (anisotropic conductive paste) layer was heated so that the temperature reached the melting point of the solder particles 10 seconds after the start of temperature rise.
  • the conductive paste (anisotropic conductive paste) layer is heated to a temperature of 250°C to harden the conductive paste (anisotropic conductive paste) layer, and the connected structure is formed. Obtained. No pressure was applied during heating.
  • Proportion X is 50% or more ⁇ : Proportion X is 30% or more and less than 50% ⁇ : Proportion X is less than 30%
  • Tackiness A conductive paste (anisotropic conductive paste) immediately after preparation was applied to the top surface of the slide glass to a thickness of 250 ⁇ m to form a conductive paste (anisotropic conductive paste) layer. Immediately after formation and 24 hours after formation, a cylindrical probe with a diameter of 5 mm was pressed against the surface of the conductive paste layer for 1 second at a pressure of 1N/5 mm ⁇ , and then the probe was pulled from the conductive paste layer at a speed of 125 mm/min. I peeled it off. The value of the peeling force at this time of peeling off was defined as the tack force. Note that the measurement was carried out at 25° C. using “Tacking Tester TAC-II” manufactured by RHESCA as a measuring device. Tackiness was evaluated based on the following criteria.
  • ⁇ The tack force immediately after formation and 24 hours later is 1N or more.
  • ⁇ The tack force immediately after formation is 1N or more, and the tack force after 24 hours is less than 1N.
  • ⁇ Immediately after formation and 24 hours later. The tack force after is less than 1N
  • Proportion Y is 70% or more
  • Proportion Y is 50% or more and less than 70%
  • Proportion Y is less than 50%
  • Connection structure 2 ... First connection target member 2a... First electrode 3... Second connection target member 3a... Second electrode 4... Connection part 4A... Solder part 4B... Cured material part

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WO2025005037A1 (ja) * 2023-06-26 2025-01-02 積水化学工業株式会社 樹脂組成物及び接続構造体の製造方法

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JP2019096550A (ja) * 2017-11-27 2019-06-20 積水化学工業株式会社 導電材料、接続構造体及び接続構造体の製造方法
WO2020255874A1 (ja) * 2019-06-20 2020-12-24 積水化学工業株式会社 導電材料、接続構造体及び接続構造体の製造方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019096550A (ja) * 2017-11-27 2019-06-20 積水化学工業株式会社 導電材料、接続構造体及び接続構造体の製造方法
WO2020255874A1 (ja) * 2019-06-20 2020-12-24 積水化学工業株式会社 導電材料、接続構造体及び接続構造体の製造方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025005037A1 (ja) * 2023-06-26 2025-01-02 積水化学工業株式会社 樹脂組成物及び接続構造体の製造方法
JP7617347B1 (ja) * 2023-06-26 2025-01-17 積水化学工業株式会社 樹脂組成物及び接続構造体の製造方法

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