Classifications

• • 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
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
  • H05K3/4007—Surface contacts, e.g. bumps
• • 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
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistors
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits
  • H05K3/321—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits by conductive adhesives
  • H05K3/323—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits by conductive adhesives by applying an anisotropic conductive adhesive layer over an array of pads
• • 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
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistors
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits
  • H05K3/34—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits by soldering
• • 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
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistors
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits
  • H05K3/34—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits by soldering
  • H05K3/3465—Application of solder
  • H05K3/3468—Application of molten solder, e.g. dip soldering
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/071—Connecting or disconnecting
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/071—Connecting or disconnecting
  • H10W72/072—Connecting or disconnecting of bump connectors
  • H10W72/07231—Techniques
  • H10W72/07236—Soldering or alloying

Definitions

• the present invention relates to a method for manufacturing a substrate with bumps and a laminate.
• solder bumps are formed on wiring circuit boards and used as external connection terminals.
• a method for manufacturing solder bumps includes, for example, the steps of providing a substrate, forming a dry film resist having openings on the substrate, filling the openings with solder paste, reflowing the solder paste, and removing the dry film resist (see, for example, Patent Document 1).
• the openings are filled with solder paste, so if the distance between the electrodes becomes narrow, the openings cannot be filled with solder paste reliably, and it may not be possible to manufacture solder bumps. This causes a problem of reduced reliability.
• the present invention provides a method for manufacturing a bumped substrate that can produce a highly reliable bumped substrate even when the distance between adjacent electrodes is narrow.
• the present invention [1] is a method for manufacturing a substrate with bumps, comprising a first step of preparing a substrate having a wiring circuit board and a plurality of electrodes arranged in the surface direction of the wiring circuit board, a second step of arranging a self-aggregating anisotropic conductive adhesive layer containing a resin component and solder particles on one surface of the substrate in the thickness direction, a third step of melting the solder particles to aggregate the molten solder particles on one surface of the electrodes in the thickness direction to form bumps, and a fourth step of removing the resin component from the substrate.
• the present invention [2] includes the method for manufacturing a bumped substrate described in [1] above, in which the maximum length of the electrodes in the surface direction of the substrate is 100 ⁇ m or less.
• the present invention [3] includes the method for manufacturing a bumped substrate described in [1] or [2] above, in which the distance between adjacent electrodes in the surface direction of the substrate is 200 ⁇ m or less.
• the present invention [4] includes the method for manufacturing a bumped substrate described in any one of [1] to [3] above, in which the self-aggregating anisotropic conductive adhesive layer contains flux.
• the present invention [5] includes the method for manufacturing a substrate with bumps described in any one of [1] to [4] above, in which both the average primary particle size of the solder particles and the average secondary particle size of the solder particles are 20 ⁇ m or less.
• the present invention [6] includes the method for manufacturing a substrate with bumps described in any one of [1] to [5] above, in which the viscosity of the resin component at the melting point of the solder particles is 5000 mPa ⁇ s or less.
• the present invention [7] includes the method for manufacturing a bumped substrate described in any one of [1] to [6] above, in which the self-aggregating anisotropic conductive adhesive layer is formed from a self-aggregating anisotropic conductive adhesive film.
• the present invention [8] is a laminate comprising a substrate having a wiring circuit board and a plurality of electrodes arranged in the surface direction of the wiring circuit board, and a self-aggregating anisotropic conductive adhesive layer containing a resin component and solder particles, arranged in this order toward one side in the thickness direction, and one surface in the thickness direction of the self-aggregating anisotropic conductive adhesive layer is exposed.
• the method for manufacturing a bumped substrate of the present invention melts the solder particles in a self-aggregating anisotropic conductive adhesive layer, causing the molten solder particles to aggregate on one surface in the thickness direction of multiple electrodes to form bumps. Therefore, even if the distance between adjacent electrodes is narrow, a highly reliable bumped substrate can be manufactured.
• the laminate of the present invention comprises, in order toward one side in the thickness direction, a substrate having a wiring circuit board and a plurality of electrodes arranged in the surface direction of the wiring circuit board, and a self-aggregating anisotropic conductive adhesive layer containing a resin component and solder particles. Therefore, by using this laminate, a highly reliable substrate with bumps can be manufactured even if the distance between adjacent electrodes spaced apart is narrow.
• FIG. 1A to 1F show an embodiment of a method for manufacturing a substrate with bumps.
• FIG. 1A shows a first step of preparing a substrate.
• FIG. 1B shows a second step of preparing a release liner.
• FIG. 1C shows a second step of arranging a self-aggregating anisotropic conductive adhesive film on one surface in the thickness direction of the release liner.
• FIG. 1D shows a second step of arranging a self-aggregating anisotropic conductive adhesive layer on one surface in the thickness direction of the substrate.
• FIG. 1E shows a third step of melting solder particles to aggregate the molten solder particles on one surface in the thickness direction of a plurality of electrodes to form bumps.
• FIG. 1A shows a first step of preparing a substrate.
• FIG. 1B shows a second step of preparing a release liner.
• FIG. 1C shows a second step of arranging a self-aggregating anisotropic conductive adhesive film on one
• FIG. 1F shows a fourth step of removing a resin component from the substrate.
• FIG. 2 shows a digital microscope photograph of the self-aggregating anisotropic conductive adhesive layer of Example 1.
• FIG. 3 shows a digital microscope photograph of the self-aggregating anisotropic conductive adhesive layer of Example 2.
• FIG. 4 shows a digital microscope photograph of the self-aggregating anisotropic conductive adhesive layer of Example 3.
• the up-down direction on the paper surface is the up-down direction (thickness direction), with the upper side of the paper surface being the top side (one side in the thickness direction) and the lower side of the paper surface being the bottom side (the other side in the thickness direction).
• the left-right direction and depth direction on the paper surface are surface directions that are perpendicular to the up-down direction. Specifically, they follow the directional arrows in each figure.
• the method for manufacturing a substrate with bumps includes a first step of preparing a substrate 2 having a wiring circuit board 11 and a plurality of electrodes 12 arranged in the surface direction of the wiring circuit board 11; a second step of arranging a self-aggregating anisotropic conductive adhesive layer 3 containing a resin component and solder particles on one thickness-wise surface of the substrate 2; a third step of melting the solder particles 5 to aggregate the molten solder particles 5 on one thickness-wise surface of the plurality of electrodes 12 to form bumps 7; and a fourth step of removing the resin component from the substrate 2.
• a substrate 2 is prepared as shown in FIG. 1A.
• the substrate 2 has a flat plate shape.
• the substrate 2 includes a wiring circuit board 11 and a plurality of electrodes 12 arranged in the surface direction of the wiring circuit board 11.
• the substrate 2 includes a wiring circuit board 11 and a plurality of electrodes 12 provided on the surface (one surface in the thickness direction) of the wiring circuit board 11.
• the wiring circuit board 11 is formed, for example, from an insulating material and a semiconductor material.
• the thickness of the wiring circuit board 11 is, for example, 5 ⁇ m or more and, for example, 1000 ⁇ m or less.
• the electrode 12 is made of metal.
• the electrodes 12 are arranged in a dot pattern on the substrate 2.
• the electrode 12 has a circular shape in a plan view. Furthermore, the multiple electrodes 12 are evenly aligned in the planar direction.
• the thickness of the electrode 12 is, for example, 0 ⁇ m or more, preferably 0.001 ⁇ m or more, and for example, 5 ⁇ m or less. When the surface of the substrate 2 and the surface of the electrode 12 are flush with each other, the thickness of the electrode 12 is 0 ⁇ m.
• the maximum length of the electrode 12 in the surface direction of the substrate 2 is, from the viewpoint of miniaturization and low height, for example, 100 ⁇ m or less, preferably 50 ⁇ m or less, more preferably 30 ⁇ m or less, even more preferably 20 ⁇ m or less, and for example, 1 ⁇ m or more.
• the distance (pitch) between adjacent electrodes 12 in the surface direction is, for example, 3 ⁇ m or more, preferably 5 ⁇ m or more, and from the viewpoint of miniaturization and low height, for example, 200 ⁇ m or less, preferably 100 ⁇ m or less, more preferably 60 ⁇ m or less, and even more preferably 40 ⁇ m or less.
• a self-aggregating anisotropic conductive adhesive layer 3 is disposed on one surface of the substrate 2 in the thickness direction.
• the self-aggregating anisotropic conductive adhesive layer 3 which will be described in detail later, refers to a layer containing solder particles 5 that self-aggregate when heated, and is distinguished from an anisotropic conductive film in which the solder particles 5 come into contact with each other when pressure is applied, for example.
• the self-aggregating anisotropic conductive adhesive layer 3 is formed from the self-aggregating anisotropic conductive adhesive film 1.
• productivity is excellent.
• a self-aggregating anisotropic conductive adhesive composition is prepared.
• the self-aggregating anisotropic conductive adhesive composition contains a resin component, solder particles 5, and, if necessary, flux.
• the self-aggregating anisotropic conductive adhesive film 1 contains a resin component, solder particles 5, and, if necessary, flux.
• the resin component includes a thermoplastic resin.
• thermoplastic resin examples include thermoplastic epoxy resin, thermoplastic phenol resin, phenoxy resin, polyolefin (e.g., polyethylene, polypropylene, ethylene-propylene copolymer, etc.), thermoplastic acrylic resin, thermoplastic polyester, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, polystyrene, polyacrylonitrile, polyamide (Nylon (registered trademark)), polycarbonate, polyacetal, polyethylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether sulfone, polyether ether ketone, polyaryl sulfone, thermoplastic polyimide, thermoplastic polyurethane, polyamino bismaleimide, polyamide imide, polyether imide, bismaleimide triazine resin, polymethylpentene, fluorinated resin, liquid crystal polymer, olefin-
• polyolefin e
• thermoplastic epoxy resins include thermoplastic bisphenol type epoxy resins (e.g., thermoplastic bisphenol A type epoxy resins, thermoplastic bisphenol F type epoxy resins, and thermoplastic bisphenol S type epoxy resins), thermoplastic novolac type epoxy resins (e.g., thermoplastic phenol novolac type epoxy resins, thermoplastic cresol novolac type epoxy resins, and thermoplastic biphenyl type epoxy resins), thermoplastic naphthalene type epoxy resins, thermoplastic fluorene type epoxy resins (e.g., bisarylfluorene type epoxy resins), and thermoplastic triphenylmethane type epoxy resins (e.g., trishydroxyphenylmethane type epoxy resins).
• thermoplastic bisphenol type epoxy resins are used as thermoplastic epoxy resins. More preferably, thermoplastic bisphenol A type epoxy resins are used as thermoplastic epoxy resins.
• thermoplastic resins may be in any form, such as solid, semi-solid, or liquid, at room temperature (25°C).
• a solid at 25°C means that it does not flow and has no viscosity at 25°C.
• a liquid at 25°C means that it has viscosity at 25°C, including liquids and fluids (the same applies below).
• the thermoplastic resin is preferably a solid thermoplastic resin.
• the softening point of the thermoplastic resin is, for example, 90°C or higher, preferably 110°C or higher, more preferably 120°C or higher, even more preferably more than 120°C, particularly preferably 125°C or higher, and, for example, 230°C or lower, preferably 200°C or lower, more preferably less than 150°C, even more preferably 140°C or lower.
• both the average primary particle size and the average secondary particle size of the solder particles 5 described below can be reduced.
• the thermoplastic resin can suppress the aggregation of the solder particles 5 in the arrangement step of the method for producing the self-aggregating anisotropic conductive adhesive film 1 described below. As a result, it is possible to reduce both the average primary particle size and the average secondary particle size of the solder particles 5 described below.
• the softening point can be measured using a thermomechanical analyzer.
• Thermoplastic resins can be used alone or in combination of two or more types.
• the content of the thermoplastic resin is, for example, 30 parts by mass or more, preferably 40 parts by mass or more, and, for example, 70 parts by mass or less, preferably 60 parts by mass or less, per 100 parts by mass of the resin component.
• the resin component optionally contains a curable resin.
• thermosetting resins examples include thermosetting epoxy resins.
• thermosetting resin examples include thermosetting epoxy resins, urea resins, melamine resins, diallyl phthalate resins, silicone resins, phenolic resins, thermosetting acrylic resins, thermosetting polyesters, thermosetting polyimides, and thermosetting polyurethanes.
• a preferred example of the curable resin is thermosetting epoxy resin.
• thermosetting epoxy resin examples include thermosetting bisphenol type epoxy resins (e.g., thermosetting bisphenol A type epoxy resins, thermosetting bisphenol F type epoxy resins, and thermosetting bisphenol S type epoxy resins), thermosetting novolac type epoxy resins (e.g., thermosetting phenol novolac type epoxy resins, thermosetting cresol novolac type epoxy resins, and thermosetting biphenyl type epoxy resins), thermosetting naphthalene type epoxy resins, thermosetting fluorene type epoxy resins (e.g., thermosetting bisarylfluorene type epoxy resins), and thermosetting triphenylmethane type epoxy resins (e.g., thermosetting trishydroxyphenylmethane type epoxy resins).
• thermosetting epoxy resin preferably, a thermosetting bisphenol type epoxy resin is used, and more preferably, a thermosetting bisphenol A type epoxy resin is used.
• thermosetting resins may be in any form, such as solid, semi-solid, or liquid, at room temperature (25°C).
• Thermosetting resin is preferably a liquid thermosetting resin.
• the resin component preferably contains a solid thermoplastic resin and a liquid thermosetting resin.
• the adhesive sheet has excellent formability and adhesive strength.
• the resin component more preferably comprises a solid thermoplastic resin and a liquid thermosetting resin.
• the curable resins can be used alone or in combination of two or more types.
• the content of the curable resin is, for example, 30 parts by mass or more, preferably 40 parts by mass or more, and, for example, 70 parts by mass or less, preferably 60 parts by mass or less, per 100 parts by mass of the resin component.
• the viscosity of the resin component at the melting point of the solder particles 5 described below is, for example, 1 mPa ⁇ s or more, preferably 100 mPa ⁇ s or more, and, for example, 5000 mPa ⁇ s or less, preferably 2000 mPa ⁇ s or less, more preferably 1000 mPa ⁇ s or less, and even more preferably 500 mPa ⁇ s or less.
• the viscosity is equal to or greater than the lower limit and equal to or less than the upper limit, the amount of unaccumulated solder particles 5 (described below) can be reduced. As a result, productivity can be improved.
• the viscosity can be measured using a rheometer.
• the method for measuring the viscosity will be described in detail in the examples below.
• the content of the resin component in the self-aggregating anisotropic conductive adhesive composition is, for example, 20% by mass or more, preferably 30% by mass or more, and, for example, 60% by mass or less, preferably 40% by mass or less.
• the mass ratio of the curable resin to the thermoplastic resin is, for example, 0.6 or more, preferably 0.9 or more, and, for example, 1.5 or less, preferably 1.1 or less.
• the solder material forming the solder particles 5 may be a solder material that does not contain lead (lead-free solder material).
• the solder material include tin and tin alloys.
• the tin alloy include tin-bismuth alloy (Sn-Bi), tin-silver-copper alloy (Sn-Ag-Cu), and tin-silver alloy (Sn-Ag).
• the tin content in the tin-silver alloy is, for example, 90% by mass or more, preferably 95% by mass or more.
• the silver content in the tin-silver alloy is, for example, 10% by mass or less, preferably 5% by mass or less.
• the tin content in the tin-silver-copper alloy is, for example, 90% by mass or more, preferably 95% by mass or more.
• the silver content in the tin-silver-copper alloy is, for example, 10% by mass or less, preferably 5% by mass or less.
• the copper content in the tin-silver-copper alloy is, for example, 1% by mass or less, preferably 0.5% by mass or less.
• the tin content in the tin-bismuth alloy is, for example, 30% by mass or more, preferably 40% by mass or more.
• the bismuth content in the tin-bismuth alloy is, for example, 70% by mass or less, preferably 60% by mass or less.
• solder materials include tin-silver alloy (Sn-Ag) and tin-silver-copper alloy (Sn-Ag-Cu).
• the melting point of the solder material (i.e., the melting point of the solder particles 5) is, for example, 260° C. or less, preferably 235° C. or less, and, for example, 100° C. or more, preferably 130° C. or more.
• the melting point is determined by differential scanning calorimetry (DSC) (same below).
• the shape of the solder particles 5 is not particularly limited, and examples thereof include a spherical shape, a plate shape, and a needle shape.
• a preferable shape of the solder particles 5 is a spherical shape. Note that although the shape of the solder particles 5 is shown as a sphere in Figs. 1C and 1D, the shape of the solder particles 5 is not limited to this.
• the surface of the solder particles 5 is generally covered with an oxide film made of an oxide of the solder material.
• the thickness of the oxide film is, for example, 1 nm or more and, for example, 20 nm or less.
• the self-aggregating anisotropic conductive adhesive film 1 contains primary particles of the solder particles 5 and/or secondary particles of the solder particles 5.
• the average primary particle diameter of the solder particles 5 and the average secondary particle diameter of the solder particles 5 are both, for example, 20 ⁇ m or less, preferably 10 ⁇ m or less, more preferably 7 ⁇ m or less, and from the standpoint of small size, low height, and reliability, are even more preferably 5 ⁇ m or less, and for example, 0.1 ⁇ m or more, preferably 0.5 ⁇ m or more.
• a primary particle is the smallest unit of a particle and is an independent particle without aggregation.
• the average primary particle diameter of the solder particles 5 is, for example, 20 ⁇ m or less, preferably 10 ⁇ m or less, more preferably 7 ⁇ m or less, and from the viewpoint of small size and low height and reliability, even more preferably 5 ⁇ m or less, and, for example, 0.1 ⁇ m or more, preferably 0.5 ⁇ m or more.
• Secondary particles are particles formed by agglomeration of primary particles.
• the average secondary particle diameter is larger than the average primary particle diameter, for example, 20 ⁇ m or less, preferably 10 ⁇ m or less, more preferably 7 ⁇ m or less, and from the viewpoint of small size, low height, and reliability, even more preferably 5 ⁇ m or less, and for example, 1 ⁇ m or more.
• the self-aggregating anisotropic conductive adhesive film 1 contains primary particles of solder particles 5 and/or secondary particles of solder particles 5.
• the self-aggregating anisotropic conductive adhesive film 1 contains only primary particles of solder particles 5, or only secondary particles of solder particles 5, or primary particles of solder particles 5 and secondary particles of solder particles 5, but in any case, both the average primary particle diameter of the solder particles 5 and the average secondary particle diameter of the solder particles 5 are, for example, 20 ⁇ m or less.
• both the average primary particle size and the average secondary particle size are equal to or less than the upper limit, unevenness in the self-aggregation described below can be suppressed. As a result, bridging (described below) can be suppressed, and reliability can be improved.
• the above average primary particle size can be measured using a laser diffraction particle size distribution analyzer.
• the method for measuring the above average secondary particle size will be described in detail in the Examples below.
• the solder particles 5 can be used alone or in combination of two or more types.
• the content of the solder particles 5 in the self-aggregating anisotropic conductive adhesive composition is, for example, 50% by mass or more, preferably 55% by mass or more, and, for example, 95% by mass or less, preferably 80% by mass or less, and more preferably 60% by mass or less.
• the flux is a component for removing the oxide film (the oxide film made of an oxide of the solder material) on the surface of the solder particles 5 .
• Examples of the flux material include organic acid salts.
• Examples of the organic acid salts include organic acids, quinolinol derivatives, and metal carbonyl acid salts.
• Examples of the organic acids include aliphatic carboxylic acids and aromatic carboxylic acids.
• Examples of the aliphatic carboxylic acids include aliphatic dicarboxylic acids. Specific examples of the aliphatic dicarboxylic acids include adipic acid, malic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, and sebacic acid.
• Examples of the aromatic carboxylic acids include benzoic acid, 2-phenoxybenzoic acid, phthalic acid, diphenylacetic acid, trimellitic acid, and pyromellitic acid.
• an organic acid is used as the flux material. More preferably, malic acid is used as the flux material.
• the melting point of the flux is, for example, 250°C or less, preferably 180°C or less, more preferably 160°C or less, and, for example, 100°C or more, preferably 120°C or more, more preferably 130°C or more.
• the shape of the flux is not particularly limited, but examples include plate, needle, and spherical shapes.
• Flux can also be dissolved in a known solvent to prepare a flux solution.
• the solids concentration of the flux solution is, for example, 10% by mass or more and, for example, 40% by mass or less.
• Flux can be used alone or in combination of two or more types.
• the content of the flux in the self-aggregating anisotropic conductive adhesive composition is, for example, 1 mass % or more, preferably 5 mass % or more, and, for example, 20 mass % or less, preferably 10 mass % or less.
• the self-aggregating anisotropic conductive adhesive composition may contain additives (for example, a curing agent, a curing accelerator, and a silane coupling agent) in appropriate proportions, if necessary.
• additives for example, a curing agent, a curing accelerator, and a silane coupling agent
• the self-aggregating anisotropic conductive adhesive composition is prepared by mixing a resin component, solder particles 5, an optional flux, and an optional additive, and stirring the mixture as required.
• solder particles 5 are mixed without stirring in the above preparation, most of the solder particles 5 will aggregate and become secondary particles. On the other hand, if the solder particles 5 are mixed with stirring in the above preparation, they will remain as primary particles.
• the self-aggregating anisotropic conductive adhesive composition can also be mixed with a known solvent to prepare the self-aggregating anisotropic conductive adhesive composition as a varnish.
• the solids concentration of the varnish containing the self-aggregating anisotropic conductive adhesive composition is, for example, 50% by mass or more, preferably 60% by mass or more, and for example, 80% by mass or less.
• the release liner is a film that covers and protects the self-cohesive anisotropic conductive adhesive film 1.
• the release liner 10 has a film shape.
• the release liner 10 is, for example, a plastic substrate (plastic film).
• plastic substrates include polyester sheets (polyethylene terephthalate (PET) sheets), polyolefin sheets (e.g., polyethylene sheets, polypropylene sheets), polyvinyl chloride sheets, polyimide sheets, and polyamide sheets (nylon sheets).
• PET polyethylene terephthalate
• polyolefin sheets e.g., polyethylene sheets, polypropylene sheets
• polyvinyl chloride sheets e.g., polyethylene sheets, polypropylene sheets
• polyamide sheets nylon sheets.
• the surface of the release liner 10 may be subjected to a surface treatment such as silicone treatment.
• the thickness of the release liner 10 is, for example, 1 ⁇ m or more and, for example, 100 ⁇ m or less.
• a self-cohesive anisotropic conductive adhesive film 1 is placed on one surface of the release liner 10 in the thickness direction.
• a self-aggregating anisotropic conductive adhesive composition (varnish of a self-aggregating anisotropic conductive adhesive composition) is applied to one surface in the thickness direction of the release liner 10, and then dried as necessary.
• the drying conditions are, for example, a drying temperature of 40°C or higher and, for example, 100°C or lower.
• the drying time is, for example, 1 minute or longer and, for example, 60 minutes or shorter.
• the heating during the drying process may cause the resin components to flow, which may cause the solder particles 5 to flow accordingly. This causes some or all of the solder particles 5 to aggregate and become secondary particles.
• the higher the drying temperature the more the solder particles 5 tend to aggregate, but by increasing the softening point of the thermoplastic resin described above, the flow of the resin components can be suppressed, and the aggregation of the solder particles 5 can be suppressed even if the drying temperature is high.
• the drying temperature is adjusted so that the difference between the softening point of the thermoplastic resin and the drying temperature (softening point of the thermoplastic resin - drying temperature) is, for example, 50°C or higher, and preferably 60°C or higher.
• the above steps produce a self-cohesive anisotropic conductive adhesive film 1 that is arranged on one side of the release liner 10 in the thickness direction.
• Such a self-aggregating anisotropic conductive adhesive film 1 contains a resin component and solder particles 5 (primary particles and secondary particles of solder particles 5) dispersed in the resin component. Note that in FIG. 1C, solder particles 5 are described without distinguishing between primary particles and secondary particles (the same applies below).
• the thickness of the self-aggregating anisotropic conductive adhesive film 1 is, for example, 15 ⁇ m or less, preferably 7 ⁇ m or less, more preferably 6 ⁇ m or less, and for example, 1 ⁇ m or more.
• a self-aggregating anisotropic conductive adhesive film 1 is placed on one surface in the thickness direction of the substrate 2, and the release liner 10 is peeled off. This places a self-aggregating anisotropic conductive adhesive layer 3 on one surface in the thickness direction of the substrate 2.
• the second process produces a laminate 6 having a substrate 2 and a self-aggregating anisotropic conductive adhesive layer 3 arranged in order toward one side in the thickness direction.
• the laminate 6 includes only one substrate 2 and one self-aggregating anisotropic conductive adhesive layer 3.
• This laminate 6 is distinguished from a laminate 6 in which one self-aggregating anisotropic conductive adhesive layer 3 is sandwiched between two substrates 2.
• Such a laminate 6 can be traded commercially as a component of the bumped substrate 20.
• ⁇ Third step> In the third step, as shown in FIG. 1E, the solder particles 5 are melted to cause the molten solder particles 5 to aggregate on one surface in the thickness direction of the plurality of electrodes 12, thereby forming bumps 7.
• the laminate 6 is heated.
• the heating temperature is equal to or higher than the melting point of the solder particles 5, and, if the resin component contains a curable resin, is lower than the curing temperature of the curable resin.
• the heating temperature is, for example, 100°C or higher, preferably 130°C or higher, and, for example, 300°C or lower, preferably 280°C or lower, and more preferably 270°C or lower.
• the heating time is, for example, 120 seconds or less, preferably 60 seconds or less, more preferably 30 seconds or less, and even more preferably 10 seconds or less, and 1 second or more.
• the heating temperature and heating time are equal to or higher than the lower limit and equal to or lower than the upper limit, and if the resin component contains a curable resin, the solder particles 5 can be melted without curing the curable resin, and the molten solder particles 5 can be caused to self-aggregate (described below) into multiple electrodes 12. Because the curable resin is not cured, the resin components (particularly the curable resin) can be more reliably removed in the fourth step described below.
• solder particles 5 melt due to this heating.
• the melted solder particles 5 gather (self-aggregate) on one side of the thickness direction of the multiple electrodes 12 to form bumps 7.
• the resin components are removed from the substrate 2, and the flux, which is added as required, the additives, which are added as required, and the unaccumulated solder particles 5 are also removed.
• a cleaning solution is used to dissolve the resin components from the substrate 2.
• the cleaning liquid is selected appropriately depending on the type of resin component.
• cleaning liquids include organic solvents (e.g., methyl ethyl ketone) and water.
• the method for removing the resin component from the substrate 2 is not particularly limited, but an example is a method in which the substrate 2 after the third step is immersed in a cleaning solution and subjected to ultrasonic treatment.
• the bumped substrate 20 comprises a wiring circuit board 11, a substrate 2 having a plurality of electrodes 12 arranged in the surface direction of the wiring circuit board 11, and a bump 7 covering one surface of the electrodes 12 on the substrate 2 in the thickness direction.
• the bumps 7 are preferably used as external connection terminals.
• the method for manufacturing the bumped substrate 20 involves melting the solder particles 5 in the self-aggregating anisotropic conductive adhesive layer 3, causing the molten solder particles 5 to aggregate on one surface in the thickness direction of the multiple electrodes 12, thereby forming bumps 7. Therefore, even if the distance between adjacent electrodes 12 spaced apart is narrow, a highly reliable bumped substrate 20 can be manufactured.
• this method utilizes the self-aggregation of the solder particles 5 when forming the bumps 7, so even if the distance (pitch) between adjacent electrodes 12 is narrow (specifically, even if the distance (pitch) between adjacent electrodes 12 is 200 ⁇ m), the bumps 7 can be reliably formed. This provides excellent reliability.
• the self-aggregation of the solder particles 5 is utilized, so that it is possible to prevent adjacent bumps 7 in the planar direction from being electrically connected (i.e., two adjacent electrodes 12 from being electrically connected (bridged)). Therefore, even if the distance between adjacent electrodes 12 is narrow, excellent reliability is achieved.
• the laminate 6 also includes a wiring circuit board 11, a substrate 2 having a plurality of electrodes 12 arranged in the surface direction of the wiring circuit board 11, and a self-aggregating anisotropic conductive adhesive layer 3, which are arranged in order toward one side in the thickness direction. Therefore, by using this laminate 6, a highly reliable substrate 20 with bumps can be manufactured even if the distance between adjacent electrodes 12 is narrow.
• the electrodes 12 are arranged in a dot pattern, but the arrangement of the electrodes 12 is not limited to this.
• the electrode 12 has a circular shape in a planar view, but the shape of the electrode 12 is not limited to this and may be, for example, a square shape in a planar view.
• the self-aggregating anisotropic conductive adhesive layer 3 is formed from the self-aggregating anisotropic conductive adhesive film 1, but there are no particular limitations as long as it is capable of forming the self-aggregating anisotropic conductive adhesive layer 3; for example, an anisotropic conductive adhesive paste may also be used.
• the self-aggregating anisotropic conductive adhesive paste contains a resin component, solder particles 5, a flux that is mixed in as needed, and an additive that is mixed in as needed.
• the anisotropic conductive adhesive paste is applied to one surface in the thickness direction of the substrate 2, and dried as necessary to form a self-aggregating anisotropic conductive adhesive layer 3.
• jER1004 Bisphenol A type epoxy resin, solid at 25°C, thermoplastic resin, softening point 97°C, manufactured by Mitsubishi Chemical Corporation
• jER1007 Bisphenol A type epoxy resin, solid at 25°C, thermoplastic resin, softening point 128°C, manufactured by Mitsubishi Chemical Corporation
• jER1009 Bisphenol A type epoxy resin, solid at 25°C, thermoplastic resin, softening point 144°C, manufactured by Mitsubishi Chemical Corporation jER1010: Bisphenol A type epoxy resin, solid at 25°C, thermoplastic resin, softening point 144°C, manufactured by Mitsubishi Chemical Corporation Phenol A type epoxy resin, solid at 25°C, thermoplastic resin, softening point 150°C or higher, manufactured by Mitsubishi Chemical Corporation jER828: bisphenol A type epoxy resin, epoxy equivalent 184-194g/eq, liquid at 25°C, thermosetting resin, manufactured by Mitsubishi Chemical Corporation S
• the resin component, solder particles, and flux were mixed according to the formulation shown in Table 1, and added to methyl ethyl ketone (MEK) to prepare a self-aggregating anisotropic conductive adhesive composition (solid concentration 70% by mass).
• MEK methyl ethyl ketone
• the flux used was a flux solution (solid concentration 30% by mass) in which malic acid was added and dissolved in ethanol.
• a release liner was prepared.
• a self-aggregating anisotropic conductive adhesive film was placed on one surface of the release liner in the thickness direction.
• a varnish of a self-aggregating anisotropic conductive adhesive composition was applied to one surface of the release liner in the thickness direction, and then dried.
• the drying temperature was 60°C, and the drying time was 5 minutes.
• a self-aggregating anisotropic conductive adhesive film (thickness 5 ⁇ m) was prepared on one surface of the release liner in the thickness direction.
• a self-aggregating anisotropic conductive adhesive film was placed on one surface of the substrate in the thickness direction. This resulted in a self-aggregating anisotropic conductive adhesive layer being placed on one surface of the substrate in the thickness direction, resulting in a laminate.
• the laminate was placed on a hot plate preheated to 40° C., and then heated to 260° C. (170° C. in Examples 5 and 7) at a heating rate of 20° C./sec, kept at that temperature for 5 seconds, and then cooled again by radiation to 40° C. This caused the solder particles to melt, and the molten solder particles were agglomerated on one surface in the thickness direction of the multiple electrodes to form bumps.
• the still images obtained were binarized using the "Threshold" function of the image processing software "imageJ, developed by Wayne Rasband (NIH)".
• imageJ developed by Wayne Rasband
• a straight line was drawn from one side of the captured image to the corresponding side, and the pixels on that line were displayed in grayscale.
• the number of pixels was counted for each part that continuously showed a value of 255 in grayscale notation.
• the number of pixels in the length of the scale bar in the image (100 ⁇ m) was counted and standardized by this to determine the secondary particle diameter of the solder particles from each part that continuously showed a value of 255 in grayscale notation, and these were averaged to calculate the average secondary particle diameter of the solder particles.
• Table 1 The results are shown in Table 1.
• the bumped substrate and laminate produced by the bumped substrate manufacturing method of the present invention are suitable for use as external connection terminals in the manufacture of electronic devices.

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• 2023
  • 2023-09-27 JP JP2024550431A patent/JPWO2024071266A1/ja active Pending
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