Electroconductive resin composition, electroconductive resin sheet, connected structure, and method for producing connected structure

Abstract

Provided is an electroconductive resin composition comprising solder particles, a resin component, and a flux. The electroconductive resin composition contains no hardener or contains a hardener in an amount less than 5 parts by mass per 100 parts by mass of the resin component. The flux is a dicarboxylic acid compound. The dicarboxylic acid compound contains no hydroxyl group, and the number of carbon atoms present between the two carboxyl groups is 2-9.

Description

Conductive resin composition, conductive resin sheet, connection structure, and method for manufacturing the connection structure

[0001] The present invention relates to a conductive resin composition, a conductive resin sheet, a connection structure, and a method for manufacturing the connection structure.

[0002] Conventionally, a conductive resin sheet made of a conductive resin composition is used to connect the electrodes of two printed circuit boards, and the conductive resin sheet is formed from the conductive resin composition containing solder particles, a curable resin, and a flux.

[0003] The conductive resin sheet is first placed between two printed circuit boards. The conductive resin sheet is then heated. This softens the curable resin, and the melted solder particles gather and agglomerate between the electrodes (self-agglomeration). The curable resin then hardens around the solder. The agglomerated solder solidifies as the temperature is lowered, forming a solder part. The curable resin forms a cured resin part around the solder part.

[0004] As such a conductive resin composition, for example, an anisotropic conductive paste is known which contains lead-free solder powder, a thermosetting resin, adipic acid as a flux, and a curing agent, with the content of the curing agent being 14 parts by mass per 100 parts by mass of the resin component (see, for example, Example 1 of Patent Document 1).

[0005] JP 2012-216770 A

[0006] On the other hand, the anisotropic conductive paste of Patent Document 1 contains a large amount of curing agent to promote rapid curing of the thermosetting resin. In this case, voids occur in the cured resin and curing is insufficient, resulting in a reduced adhesive strength of the anisotropic conductive paste. Furthermore, the resin hardens faster than the solder particles can sufficiently accumulate (self-aggregate) between the electrodes, resulting in insufficient electrical connection.

[0007] The present invention provides a conductive resin composition that can improve adhesion reliability and more easily achieve reliable electrical connection, a conductive resin sheet containing the conductive resin composition, a connection structure connected using the conductive resin composition, and a method for manufacturing the connection structure.

[0008] The present invention [1] is a conductive resin composition comprising solder particles, a resin component, and a flux, and not comprising a curing agent, or if comprising a curing agent, the content of the curing agent is less than 5 parts by mass per 100 parts by mass of the resin component, and the flux is a dicarboxylic acid compound, which does not contain a hydroxyl group and has 2 or more and 9 or less carbon atoms between two carboxyl groups.

[0009] The present invention [2] includes the conductive resin composition according to the above [1], wherein the melting point of the solder particles is 150° C. or higher.

[0010] The present invention [3] includes the conductive resin composition according to the above [1] or [2], wherein the solder particles contain Sn.

[0011] The present invention [4] includes the conductive resin composition according to any one of the above [1] to [3], wherein the resin component includes a liquid resin and a solid resin.

[0012] The present invention [5] includes a conductive resin sheet containing the conductive resin composition according to any one of the above [1] to [4].

[0013] The present invention [6] includes a connection structure comprising a first substrate, a second substrate arranged at a distance in the thickness direction, and an adhesive layer interposed between the first substrate and the second substrate, each of the first substrate and the second substrate having at least one electrode, a columnar solder portion disposed between the electrode of the first substrate and the electrode of the second substrate, and the adhesive layer and the columnar solder portion formed from the conductive resin composition described in any one of [1] to [4] above.

[0014] The present invention [7] includes the connection structure according to the above [6], in which the conductive resin composition has a shear adhesive strength of greater than 1.0 MPa at 260°C when cured.

[0015] The present invention [8] includes the connection structure according to the above [6], in which the columnar solder portion exhibits anisotropy that exists only between the electrodes.

[0016] The present invention [9] includes a method for manufacturing a connection structure, comprising: a first step of preparing a plurality of substrates each having a plurality of electrodes arranged in a planar direction; a second step of preparing a conductive resin sheet by applying the conductive resin composition described in any one of [1] to [4] above; a third step of stacking the two substrates with the conductive resin sheet sandwiched therebetween so that the electrodes of the two substrates face each other, thereby manufacturing a laminate; and a fourth step of heating the laminate and melting the solder particles to form columnar solder portions so as to electrically connect the electrodes of the two substrates, and curing the resin component.

[0017] The present invention

[10] includes the method for manufacturing a connection structure according to the above [9], in which the fourth step is carried out in a pressure oven.

[0018] According to the present invention, the solder paste contains solder particles, a resin component, and a flux, and does not contain a curing agent, or if a curing agent is contained, the content of the curing agent is less than 5 parts by mass per 100 parts by mass of the resin component, and the flux is a dicarboxylic acid compound that does not contain a hydroxyl group and has 2 or more and 9 or less carbon atoms between the two carboxyl groups. Therefore, improved adhesive reliability and reliable electrical connection can be more easily achieved.

[0019] FIG. 1 shows one embodiment of a conductive resin sheet containing a conductive resin composition. FIG. 2 shows one embodiment of a connection structure connected by the conductive resin sheet shown in FIG. 1. FIGS. 3A to 3E show one embodiment of a method for manufacturing the connection structure shown in FIG. 2. FIG. 3A shows a first step of preparing two substrates each having a plurality of electrodes arranged in the surface direction. FIG. 3B shows a second step of preparing a conductive resin sheet by applying a conductive resin composition. FIG. 3C shows a third step of manufacturing a laminate by stacking a first substrate and a second substrate with a conductive resin sheet sandwiched therebetween so that the electrodes of the two substrates face each other. FIG. 3D shows a sixth step of thermocompression bonding the first substrate and the second substrate to the conductive resin sheet. FIG. 3E shows a fourth step of forming an adhesive layer that solder-connects the first substrate and the second substrate to the conductive resin sheet.

[0020] 1. Conductive Resin Composition The conductive resin composition contains solder particles, a resin component, and a flux. The conductive resin composition does not contain a curing agent, or if it contains a curing agent, the content of the curing agent is less than 5 parts by mass per 100 parts by mass of the resin component.

[0021] <Solder Particles> From the viewpoint of environmental friendliness, a solder material that does not contain lead (lead-free solder material) is preferably used as the solder material that forms the solder particles. From the viewpoint of further promoting the resin curing action of the flux by metal catalytic action, the solder material preferably contains tin (Sn). Examples of solder materials that contain tin include tin and tin alloys. Examples of tin alloys include tin-bismuth alloys (Sn—Bi), tin-silver-copper alloys (Sn—Ag—Cu), and tin-silver alloys (Sn—Ag). Examples of solder materials that are preferably used include tin-silver-copper alloys (Sn—Ag—Cu) and tin-bismuth alloys (Sn—Bi).

[0022] 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.

[0023] The tin content in the tin-bismuth alloy is, for example, 80 mass % or less, or preferably 50 mass % or less, and the bismuth content in the tin-bismuth alloy is, for example, 20 mass % or more, or preferably 50 mass % or more.

[0024] The melting point of the solder material (i.e., the melting point of the solder particles) is higher than the softening point of the solid resin described below, and the lower limit is, for example, 120°C or higher, preferably 150°C or higher, more preferably 180°C or higher, and even more preferably 200°C or higher. The upper limit is, for example, 280°C or lower, preferably 260°C or lower, and more preferably 240°C or lower. The melting point can be determined by differential scanning calorimetry (DSC) (the same applies hereinafter).

[0025] The shape of the solder particles is not particularly limited, and examples thereof include a spherical shape, a plate shape, and a needle shape. A preferred shape of the solder particles is a spherical shape.

[0026] From the viewpoint of miniaturizing and reducing the height of the connection structure, the average primary particle diameter of the solder particles is, for example, 20 μm or less, preferably 10 μm or less. Also, for example, 0.1 μm or more, preferably 0.5 μm or more. The average primary particle diameter can be measured using a laser diffraction particle size distribution analyzer.

[0027] The solder particles can be used alone or in combination of two or more kinds.

[0028] The solder particles may be either acid-treated or untreated.

[0029] [Acid-Treated Solder Particles] The acid-treated solder particles are obtained by treating solder particles with an acid treating agent. The acid treating agent is a component for removing an oxide film on the surface of the solder particles.

[0030] The acid treating agent has a carboxyl group. Examples of such an acid treating agent include a carboxylic acid treating agent. Examples of the carboxylic acid treating agent include a monocarboxylic acid treating agent, a dicarboxylic acid treating agent, and a trifunctional or higher functional carboxylic acid treating agent.

[0031] The acid treating agent is preferably a dicarboxylic acid treating agent, more preferably an aliphatic dicarboxylic acid treating agent, and even more preferably malic acid.

[0032] The acid treating agents can be used alone or in combination of two or more kinds.

[0033] <Resin Component> The resin component is not particularly limited, but preferably contains a solid resin and a liquid resin. When the resin component contains a solid resin and a liquid resin, the conductive resin sheet has excellent formability and adhesive strength.

[0034] A solid resin does not flow and has no viscosity at 25° C. A liquid resin includes liquids and fluids at 25° C. and has viscosity.

[0035] The solid resin includes thermosetting resins and thermoplastic resins. The solid resin may include either or both of thermosetting resins and thermoplastic resins, but preferably includes only thermosetting resins.

[0036] The liquid resin includes thermosetting resins and thermoplastic resins. The liquid resin may include either or both of thermosetting resins and thermoplastic resins, but preferably includes only thermosetting resins.

[0037] The resin component more preferably comprises a solid thermosetting resin and a liquid thermosetting resin.

[0038] The mass ratio of the solid resin to the liquid resin in the resin component is, for example, 0.5 to 1.5, preferably 0.7 to 1.3, and more preferably 0.9 to 1.1.

[0039] Alternatively, the resin component may be blended with a known solvent to prepare a varnish containing the resin component. The solid content of the varnish containing the resin component is, for example, 30% to 80% by mass, preferably 40% to 70% by mass.

[0040] The content of the resin component relative to the conductive resin composition is, for example, 20% by mass to 60% by mass, preferably 30% by mass to 50% by mass, and more preferably 33% by mass to 45% by mass.

[0041] The softening point of the solid resin is lower than the melting point of the solder particles. More specifically, in order to soften the solid resin without melting the solder particles in the thermocompression bonding in the sixth step described later, the softening point of the solid resin is lower than the melting point of the solder particles. The softening point of the solid resin is, for example, 40°C or higher, preferably 60°C or higher, and more preferably 80°C or higher, and is, for example, 200°C or lower, preferably 180°C or lower, more preferably less than 150°C, and even more preferably 140°C or lower.

[0042] The softening point can be measured using a thermomechanical analyzer. [Thermosetting Resin] Examples of the thermosetting resin include thermosetting epoxy resin, urea resin, melamine resin, diallyl phthalate resin, silicone resin, phenolic resin, thermosetting acrylic resin, thermosetting polyester, thermosetting polyimide, and thermosetting polyurethane. A preferred example of the thermosetting resin is thermosetting epoxy resin.

[0043] Examples of thermosetting epoxy resins 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). A preferred example of the thermosetting epoxy resin is a thermosetting bisphenol-type epoxy resin. A more preferred example of the thermosetting epoxy resin is a thermosetting bisphenol A-type epoxy resin. The epoxy equivalent of the thermosetting epoxy resin, when it is a liquid resin, is preferably 150 to 240, more preferably 170 to 220. The epoxy equivalent of the thermosetting epoxy resin is preferably 800 to 3,000, more preferably 1,400 to 2,000, in the case of a solid resin.

[0044] These thermosetting resins may be either solid or liquid at room temperature (25° C.).

[0045] The curing temperature of the thermosetting resin is equal to or higher than the melting point of the solder particles, for example, 150°C to 280°C, preferably 160°C to 260°C, and more preferably 170°C to 250°C.

[0046] The thermosetting resins can be used alone or in combination of two or more kinds.

[0047] The content of the thermosetting resin is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, per 100 parts by mass of the resin component, and is, for example, 100 parts by mass or less.

[0048] [Thermoplastic Resin] Examples of thermoplastic resins include thermoplastic epoxy resins, thermoplastic phenolic resins, phenoxy resins, polyolefins (e.g., polyethylene, polypropylene, ethylene-propylene copolymers, etc.), thermoplastic acrylic resins, thermoplastic polyesters, polyvinyl acetate, ethylene-vinyl acetate copolymers, polyvinyl chloride, polystyrene, polyacrylonitrile, polyamide (Nylon (registered trademark)), polycarbonate, polyacetal, polyethylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether sulfone, polyether ether ketone, polyallylsulfone, thermoplastic polyimide, thermoplastic polyurethane, polyaminobismaleimide, polyamideimide, polyetherimide, bismaleimide triazine resin, polymethylpentene, fluorinated resins, liquid crystal polymers, olefin-vinyl alcohol copolymers, ionomers, polyarylates, acrylonitrile-ethylene-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, and butadiene-styrene copolymers.

[0049] The thermoplastic resins can be used alone or in combination of two or more kinds.

[0050] The content of the thermoplastic resin is, for example, 0 parts by mass or more and, for example, 50 parts by mass or less, and preferably 20 parts by mass or less, per 100 parts by mass of the resin component.

[0051] <Flux> The flux is a dicarboxylic acid compound that does not contain a hydroxyl group and has two or more but nine or less carbon atoms between two carboxyl groups. This not only removes oxide films from the surfaces of the solder particles and the electrodes (specifically, the first and second electrodes described below), but also provides an appropriate resin curing effect in the conductive resin composition. As a result, improved adhesion reliability and reliable electrical connection can be more easily achieved. The resin curing effect in the conductive resin composition will be described in detail below.

[0052] A dicarboxylic acid compound has two highly reactive carboxyl groups. As described above, the reactivity of the two carboxyl groups is higher when the number of carbon atoms between the two carboxyl groups is 2 or more and 9 or less. Furthermore, since the dicarboxylic acid compound does not have a hydroxyl group, the generation of gas derived from the hydroxyl group is suppressed, thereby suppressing the generation of voids.

[0053] The number of carbon atoms between the two carboxyl groups of a dicarboxylic acid compound being 2 or more and 9 or less means that the number of carbon atoms between the carbon atoms of the two carboxyl groups (—COOH) is 2 or more and 9 or less, and does not include the number of carbon atoms in the carboxyl groups and the number of carbon atoms in the side chain portion. For example, in the case of an aliphatic dicarboxylic acid, the number of carbon atoms between the two carboxyl groups is 2 or more and 9 or less as in glutaric acid (C ５ H ８ O ４ ) 3,3-dimethylglutaric acid (C ７ H １２ O ４ ) 3, adipic acid (C ６ H １０ O ４ On the other hand, for example, dodecanedioic acid (C １２ H ２２ O ４ ) is 10, so the formula (5) below is malic acid (C ４ H ６ O ５Although the carbon number in the formula (4) is 2, the compounds of the formula (5) have a hydroxyl group, and therefore are not included in the dicarboxylic acid defined above. The number of carbon atoms present between the dicarboxylic acids is preferably 3 to 5, and more preferably 3.

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] Examples of such dicarboxylic acid compounds that satisfy the above requirements include aliphatic dicarboxylic acids. Examples of aliphatic dicarboxylic acids include linear saturated dicarboxylic acids, branched saturated dicarboxylic acids, linear unsaturated dicarboxylic acids, and branched unsaturated dicarboxylic acids. These dicarboxylic acids may have a substituent (excluding a hydroxyl group) in a moiety other than the carboxyl group.

[0060] Examples of linear saturated dicarboxylic acids include succinic acid (2), glutaric acid (3), adipic acid (4), pimelic acid (5), suberic acid (6), azelaic acid (7), and sebacic acid (8).

[0061] Examples of branched saturated dicarboxylic acids include 3,3-dimethylglutaric acid (3).

[0062] Examples of the straight-chain unsaturated dicarboxylic acid include fumaric acid (2).

[0063] Among these, from the viewpoint of an appropriate resin curing action, aliphatic dicarboxylic acids are preferred, and linear saturated dicarboxylic acids and branched saturated dicarboxylic acids are more preferred. Glutaric acid (3), adipic acid (4), pimelic acid (5), and 3,3-dimethylglutaric acid (3) are even more preferred, with glutaric acid (3) and 3,3-dimethylglutaric acid (3) being particularly preferred, and 3,3-dimethylglutaric acid (3) being most preferred. The number in parentheses after the compound name indicates the number of carbon atoms present between the two carboxyl groups.

[0064] Furthermore, when comparing linear or branched saturated dicarboxylic acids with linear or branched unsaturated dicarboxylic acids, linear or branched saturated dicarboxylic acids are less likely to undergo dehydration condensation reactions due to the greater distance between carbon atoms, and therefore, the use of linear or branched saturated dicarboxylic acids can suppress the generation of voids.

[0065] Furthermore, a salt of the above dicarboxylic acid compound can also be used as the flux.

[0066] The fluxes can be used alone or in combination of two or more kinds.

[0067] Alternatively, the flux may be mixed with a known solvent (e.g., ethanol) to prepare a solution of the flux. The solid content of the flux solution is, for example, 10% by mass to 50% by mass, preferably 20% by mass to 40% by mass.

[0068] The content of the flux is, for example, 3 parts by mass or more, preferably 6 parts by mass or more, more preferably 9 parts by mass or more, and particularly preferably 13 parts by mass or more, per 100 parts by mass of the resin component, from the viewpoint of fully exerting the resin curing action. Furthermore, from the viewpoint of slowing the resin curing rate, the content is, for example, 30 parts by mass or less, preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and particularly preferably 17 parts by mass or less, per 100 parts by mass of the resin component. Furthermore, by keeping the content within the range specified by the above upper and lower limits, improved adhesion reliability and reliable electrical connection can be more easily achieved.

[0069] The content of the flux is, for example, 1 part by mass or more, or preferably 5 parts by mass or more, per 100 parts by mass of the solder particles, from the viewpoint of further removing the oxide film on the surface of the solder particles.

[0070] The content of the flux relative to the conductive resin composition is, for example, 1 to 10 mass %, or preferably 3 to 7 mass %.

[0071] <Curing Agent> The conductive resin composition does not contain a curing agent, or if it contains a curing agent, the content of the curing agent is less than 5 parts by mass per 100 parts by mass of the resin component. From the viewpoint of achieving a moderate curing rate of the resin component appropriate for the conductive resin composition, the content of the curing agent in the conductive resin composition is preferably 4.5 parts by mass or less, more preferably less than 3 parts by mass, and even more preferably less than 1 part by mass per 100 parts by mass of the resin component. Particularly preferably, the conductive resin composition does not contain a curing agent. In this case, the conductive resin composition consists of solder particles, a resin component, and a flux.

[0072] Examples of the curing agent include an acid anhydride curing agent, an amine curing agent, a phenol curing agent, a cationic initiator, an imidazole catalyst, and DICY (dicyandiamide).

[0073] <Other Additives> The conductive resin composition may contain other additives in an appropriate ratio, if necessary. For example, a curing aid may be used. Although a curing aid may or may not be used, it is preferable not to use one, from the viewpoint of preventing an excessive increase in viscosity during the heating and temperature rise process of the conductive resin composition and not inhibiting the accumulation of solder.

[0074] 2. Method for producing conductive resin composition The conductive resin composition is produced by mixing solder particles, a resin component, a flux, and, if necessary, a curing agent. Specifically, the solder particles, the resin component, the flux, and, if necessary, the curing agent and additives are mixed and stirred as necessary. This produces the conductive resin composition.

[0075] Alternatively, the conductive resin composition may be blended with a known solvent to prepare a varnish of the conductive resin composition. The solid content of the varnish of the conductive resin composition is, for example, 50% by mass to 80% by mass, preferably 60% by mass to 75% by mass.

[0076] Next, the conductive resin sheet obtained using this conductive resin composition will be described in detail.

[0077] 3. Conductive Resin Sheet The conductive resin sheet is formed into a sheet shape from a conductive resin composition. That is, the conductive resin sheet contains a conductive resin composition.

[0078] 1, the conductive resin sheet 1 is disposed on one surface in the thickness direction of a release liner 10. In the conductive resin sheet 1, solder particles 5 are dispersed in the resin component.

[0079] From the viewpoint of making the connection structure smaller and thinner, the thickness of the conductive resin sheet 1 is, for example, 50 μm or less, preferably 25 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, and for example, 1 μm or more.

[0080] The conductive resin sheet 1 is produced by applying a conductive resin composition (a varnish of the conductive resin composition) to one surface in the thickness direction of the release liner 10, and then drying it as necessary. As drying conditions, the drying temperature is, for example, 40° C. or higher to 100° C. The drying time is, for example, 1 minute to 60 minutes.

[0081] As described above, the release liner 10 is a support for supporting the conductive resin sheet 1. The release liner 10 is, for example, a plastic substrate (plastic film) in the form of a film. The thickness of the release liner 10 is, for example, 1 μm to 100 μm.

[0082] 2, a connection structure 20 is manufactured by connecting two substrates (first substrate 2, second substrate 4), each having an electrode, using the above-described conductive resin sheet 1. When the conductive resin sheet 1 is cured, it forms a columnar solder portion 15 and an adhesive layer 3. In the connection structure 20, the columnar solder portion 15 is disposed between the electrodes 12, 14 of the two substrates 2, 4, and the two substrates 2, 4 are electrically connected. An adhesive layer 3 is disposed between the two substrates 2, 4 and around the columnar solder portion 15. The adhesive layer 3 includes a cured resin 16.

[0083] Specifically, connection structure 20 includes a first substrate 2, a second substrate 4 arranged at an interval in the thickness direction, and an adhesive layer 3 interposed between first substrate 2 and second substrate 4. In other words, connection structure 20 includes, in order toward one side in the thickness direction, first substrate 2, adhesive layer 3, and second substrate 4. More specifically, connection structure 20 includes first substrate 2, adhesive layer 3 arranged directly on the upper surface (one surface in the thickness direction) of first substrate 2, and second substrate 4 arranged directly on the upper surface (one surface in the thickness direction) of adhesive layer 3.

[0084] The adhesive layer 3 bonds the first substrate 2 and the second substrate 4. Specifically, the adhesive layer 3 bonds to the surface of the first substrate 2 excluding the first electrode 12. The adhesive layer 3 also bonds to the surface of the second substrate 4 excluding the second electrode 14.

[0085] The columnar solder portion 15 electrically connects the first electrode 12 and the second electrode 14 that face each other in the thickness direction. The columnar solder portion 15 has a columnar shape (specifically, a cylindrical shape) and is disposed between and in contact with the first electrode 12 and the second electrode 14. The columnar solder portion 15 exhibits anisotropy that exists only between the first electrode 12 and the second electrode 14.

[0086] In the connection structure, when the conductive resin composition is cured, the adhesive strength (shear adhesive strength) at 260°C is, for example, 1.0 MPa or more, preferably 1.1 MPa or more, more preferably 1.2 MPa or more, even more preferably 1.4 MPa or more, and particularly preferably 1.6 MPa or more. When the adhesive strength is equal to or greater than the above lower limit, the adhesive reliability can be further improved.

[0087] The shear adhesive strength of the connection structure can be measured by carrying out a die shear test using a bond tester (name "DAGE4000", manufactured by Nordson Advanced Technologies).

[0088] 5. Method for Manufacturing a Connection Structure One embodiment of a method for manufacturing a connection structure will now be described in detail with reference to FIGS. 3A to 3E.

[0089] The method for manufacturing the connection structure includes a first step of preparing a plurality of substrates each having a plurality of electrodes arranged in the surface direction; a second step of applying a conductive resin composition to prepare a conductive resin sheet 1; a third step of stacking the two substrates 2, 4 with the conductive resin sheet 1 sandwiched between them so that the electrodes of the two substrates 2, 4 face each other, thereby producing a laminate 6; and a fourth step of heating the laminate 6 and melting the solder particles 5 to form columnar solder portions 15 so as to electrically connect the electrodes of the two substrates 2, 4, and hardening the resin component.

[0090] [First Step] In the first step, a plurality of substrates each having a plurality of electrodes aligned in the surface direction are prepared. This method will be described in detail with respect to the case where two substrates each having a plurality of electrodes aligned in the surface direction are prepared. Specifically, as shown in FIG. 3A , a first substrate 2 and a second substrate 4 are prepared.

[0091] The first substrate 2 has a flat plate shape.

[0092] The first substrate 2 includes a first wired circuit board 11 and a plurality of first electrodes 12 arranged in the surface direction of the first wired circuit board 11. In other words, the first substrate 2 includes the first wired circuit board 11 and a plurality of first electrodes 12 provided on the surface (one surface in the thickness direction) of the first wired circuit board 11.

[0093] The first wired circuit board 11 is made of, for example, an insulating material and a semiconductor material.

[0094] The thickness of the first wired circuit board 11 is, for example, 5 μm to 1000 μm.

[0095] The first electrode 12 is made of a metal.

[0096] The first electrodes 12 are arranged on the first substrate 2 in, for example, a dot pattern.

[0097] More specifically, the first electrodes 12 have a circular shape in a plan view, and the first electrodes 12 are aligned and disposed evenly in the surface direction.

[0098] The thickness of the first electrode 12 is, for example, 0 μm to 20 μm, or preferably 0.001 μm to 5 μm. When the surface of the first substrate 2 and the surface of the first electrode 12 are flush with each other, the thickness of the first electrode 12 is 0 μm.

[0099] The diameter of the first electrode 12 is, for example, 1 μm to 200 μm, preferably 1 μm to 100 μm, more preferably 1 μm to 50 μm, and even more preferably 1 μm to 20 μm.

[0100] The distance (pitch) between adjacent first electrodes 12 in the surface direction is, for example, 3 μm to 400 μm, preferably 5 μm to 200 μm, more preferably 7 μm to 100 μm, and even more preferably 10 μm to 40 μm.

[0101] The second substrate 4 has a flat plate shape.

[0102] The second substrate 4 includes a second wired circuit board 13 and a plurality of second electrodes 14 arranged in the surface direction of the second wired circuit board 13. In other words, the second substrate 4 includes the second wired circuit board 13 and a plurality of second electrodes 14 provided on the surface (the other surface in the thickness direction) of the second wired circuit board 13.

[0103] The second wired circuit board 13 is made of, for example, an insulating material or a semiconductor material.

[0104] The thickness of the second wired circuit board 13 is, for example, 5 μm to 1000 μm.

[0105] The second electrode 14 is made of a metal.

[0106] The second electrodes 14 are arranged on the second substrate 4 in, for example, a dot pattern.

[0107] More specifically, the second electrodes 14 have a circular shape in a plan view, and the second electrodes 14 are aligned and disposed evenly in the surface direction.

[0108] The thickness of the second electrode 14 is, for example, 0 μm to 20 μm, or preferably 0.001 μm to 5 μm. When the surface of the second substrate 4 and the surface of the second electrode 14 are flush with each other, the thickness of the second electrode 14 is 0 μm.

[0109] The diameter of the second electrode 14 is, for example, 1 μm to 200 μm, preferably 1 μm to 100 μm, more preferably 1 μm to 50 μm, and even more preferably 1 μm to 20 μm.

[0110] Furthermore, the distance (pitch) between adjacent second electrodes 14 in the surface direction is the same as the distance (pitch) between adjacent first electrodes 12 in the surface direction described above.

[0111] [Second Step] In the second step, as shown in Fig. 3B, the conductive resin sheet 1 is prepared. Specifically, the conductive resin sheet 1 is prepared in accordance with the above-described method for manufacturing a conductive resin sheet.

[0112] [Step 3] In step 3, as shown in FIG. 3C , the first substrate 2 and the second substrate 4 are laminated with the conductive resin sheet 1 sandwiched therebetween so that the first electrode 12 of the first substrate 2 and the second electrode 14 of the second substrate 4 face each other, thereby producing a laminate 6.

[0113] Specifically, first, the first substrate 2 and the second substrate 4 are brought close to the conductive resin sheet 1, and the first substrate 2 and the second substrate 4 are brought into contact with the conductive resin sheet 1. More specifically, one thickness-wise surface of the first substrate 2 is brought into contact with the other thickness-wise surface of the conductive resin sheet 1, and the other thickness-wise surface of the second substrate 4 is brought into contact with one thickness-wise surface of the conductive resin sheet 1, so that the first electrode 12 and the second electrode 14 face each other in the thickness direction.

[0114] In this way, the laminate 6 is manufactured.

[0115] [Fourth Step] In the fourth step, first, as shown in FIG. 3D, the first substrate 2 and the second substrate 4 are thermocompression-bonded to the conductive resin sheet 1.

[0116] Specifically, while the laminate 6 is being heated, the first substrate 2 and the second substrate 4 are pressed (thermocompression bonded) against the conductive resin sheet 1 .

[0117] The thermocompression bonding temperature is equal to or higher than the softening point of the solid resin and lower than the melting point of the solder particles 5. That is, in this step, the solid resin is softened without melting the solder particles 5. Specifically, the thermocompression bonding temperature is, for example, 180°C or lower, preferably 100°C or lower, more preferably 80°C or lower, and for example, 40°C or higher. The thermocompression bonding pressure is, for example, 0.001 MPa to 10 MPa, preferably 0.005 MPa to 5 MPa, more preferably 0.01 MPa to 1 MPa.

[0118] This softens the resin component, and the first electrode 12 of the first substrate 2 becomes embedded in the conductive resin sheet 1, and one surface in the thickness direction of the first substrate 2 comes into contact with the conductive resin sheet 1. Also, the second electrode 14 of the second substrate 4 becomes embedded in the conductive resin sheet 1, and the other surface in the thickness direction of the second substrate 4 comes into contact with the conductive resin sheet 1.

[0119] 3E, the laminate 6 is heated. Preferably, the laminate 6 is heated in a pressure oven 25. The pressure oven 25 is an apparatus capable of applying pressure while heating in an enclosed space, and examples thereof include an automatic heating and pressure treatment apparatus, a pressure oven, a voidless pressure oven, an autoclave, and a vacuum pressure reflow apparatus.

[0120] When the laminate 6 is heated, volatile substances may volatilize due to the heating. Such volatile substances may impair electrical connections in the laminate 6. On the other hand, when the laminate 6 is heated using the pressure oven 25, the generation of the volatile substances can be suppressed by applying pressure. As a result, the above-mentioned impediment can be suppressed.

[0121] The heating temperature is equal to or higher than the melting point of the solder particles 5. Specifically, the heating temperature is, for example, 100°C or higher, preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher, and for example, 300°C or lower, preferably 280°C or lower, and more preferably 270°C or lower.

[0122] Such heating melts the solder particles 5. The melted solder particles 5 gather (self-aggregate) between the first electrode 12 and the second electrode 14 that face each other in the thickness direction, forming columnar solder portions 15 that electrically connect the first electrode 12 and the second electrode 14. Meanwhile, the resin component in the conductive resin sheet 1 is expelled by the self-aggregating solder particles 5 and moves to the periphery of the columnar solder portions 15. Thereafter, the thermosetting resin in the resin component is thermally cured to become the cured resin 16 that bonds the first substrate 2 and the second substrate 4 together.

[0123] As a result, the columnar solder portions 15 and the adhesive layer 3 containing the cured resin 16 are formed from the conductive resin sheet 1 between the two base materials (the first substrate 2 and the second substrate 4).

[0124] From the viewpoint of making the connection structure 20 small and low-profile, the thickness of the adhesive layer 3 is less than 50 μm, preferably 25 μm or less, more preferably less than 15 μm, even more preferably 5 μm or less, and for example, 1 μm or more.

[0125] In this manner, the connection structure 20 is manufactured.

[0126] <Effects> The conductive resin composition contains solder particles, a resin component, and a flux, and does not contain a curing agent, or if it contains a curing agent, the content of the curing agent is less than 5 parts by mass per 100 parts by mass of the resin component, and the flux is a dicarboxylic acid compound that does not contain a hydroxyl group and has 2 or more and 9 or less carbon atoms between two carboxyl groups. Therefore, it is possible to improve adhesion reliability and more easily achieve reliable electrical connection.

[0127] Specifically, first, the conductive resin composition does not contain a curing agent or the content of the curing agent is significantly reduced, specifically, the content of the curing agent is less than 5 parts by mass per 100 parts by mass of the resin component, thereby suppressing rapid curing of the resin component.

[0128] On the other hand, dicarboxylic acid compounds that do not contain hydroxyl groups and have two or more but nine or less carbon atoms between two carboxyl groups exhibit the effect of a flux, i.e., the effect of removing oxide films from the solder surface, as well as the effect of curing the resin, thereby allowing the resin component to cure at an appropriate curing rate.

[0129] As a result, the occurrence of voids and poor curing in the cured resin can be suppressed, improving the connection reliability of the conductive resin sheet. In addition, because the curing speed of the resin component is appropriate, the solder particles can self-aggregate and accumulate sufficiently between the electrodes before the resin component hardens, improving the electrical connection.

[0130] The conductive resin sheet contains a conductive resin composition, which makes it possible to improve adhesion reliability and more easily achieve reliable electrical connection.

[0131] The connection structure contains a conductive resin composition, which makes it possible to improve adhesion reliability and more easily achieve reliable electrical connection.

[0132] The method for manufacturing the connection structure uses a conductive resin composition, which makes it possible to improve adhesive reliability and more easily achieve reliable electrical connection.

[0133] <Modifications> In the modification examples, the same components and steps as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, the modification examples can achieve the same effects as those in the first embodiment unless otherwise specified. Furthermore, the first embodiment and the modification examples can be combined as appropriate.

[0134] Furthermore, in the above description, the first electrodes 12 and the second electrodes 14 are arranged in a dot pattern, but the arrangement of the first electrodes 12 and the second electrodes 14 is not limited to this.

[0135] Furthermore, in the above description, the first electrode 12 and the second electrode 14 have a circular shape when viewed from above, but the shapes of the first electrode 12 and the second electrode 14 are not limited to this and may be, for example, a square shape when viewed from above.

[0136] In the above description, the second substrate 4 may be, for example, a chip component (for example, a mini / micro LED).

[0137] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be substituted with the corresponding upper limit values ​​(numeric values ​​defined as "equal to or less than") or lower limit values ​​(numeric values ​​defined as "equal to or more than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the above "Modes for Carrying Out the Invention."

[0138] 1. Test 1 Evaluation of solder accumulation state and adhesive strength <Details of components> The trade names (names) and abbreviations of the components used in each example and comparative example are described in detail below. Solder particles (name "Sn96.5Ag3Cu0.5 ST-3" (hereinafter referred to as "ST-3")): 96.5% by mass of Sn, 3.0% by mass of Ag, 0.5% by mass of copper, melting point 217-219°C, spherical shape, average primary particle diameter 3 μm, manufactured by Mitsui Mining & Smelting Co., Ltd. Solder particles (name "Sn96.5Ag3Cu0.5 ST-7" (hereinafter referred to as "ST-7")): 96.5% by mass of Sn, 3.0% by mass of Ag, 0.5% by mass of copper, melting point 217-219°C, spherical shape, average primary particle diameter 7 μm, manufactured by Mitsui Mining & Smelting Co., Ltd. Solder particles (name "Sn42Bi58 ST-7"): 42% by mass of Sn, 58% by mass of Bi, melting point 139°C, spherical shape, average primary particle diameter 7 μm, manufactured by Mitsui Mining & Smelting Co., Ltd. 3,3-Dimethylglutaric acid: manufactured by Merck KCaA Glutaric acid: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Adipic acid: manufactured by Tokyo Chemical Industry Co., Ltd. Pimelic acid: manufactured by Tokyo Chemical Industry Co., Ltd. Azelaic acid: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Malic acid (name "DL-malic acid"): manufactured by Tokyo Chemical Industry Co., Ltd. Dodecanedioic acid: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Liquid epoxy resin (name "jER828"): bisphenol A type epoxy resin, epoxy equivalent 184 to 194 g / eq, liquid at 25°C, thermosetting resin, manufactured by Mitsubishi Chemical Corporation Solid epoxy resin (name "NPES907"): bisphenol A type epoxy resin, epoxy equivalent 1500 to 1600 g / eq, solid at 25°C, thermosetting resin, softening point 120 to 130°C, manufactured by Nan'a Plastics Co., Ltd. Solid phenolic resin (name "MEH-7851-H": phenol novolac resin, thermosetting resin, softening point 64°C to 85°C, manufactured by UBE Corporation. Solid epoxy resin (name "NC-3000H"): biphenyl-type epoxy resin, epoxy equivalent 290 g / eq, thermosetting resin, softening point 71°C, manufactured by Nippon Kayaku Co., Ltd. Curing agent (name "SAN-AID SI-B3"): thermal cationic polymerization initiator, manufactured by Sanshin Chemical Industry Co., Ltd. Curing agent (name "SAN-AID SI-B4"): thermal cationic polymerization initiator, manufactured by Sanshin Chemical Industry Co., Ltd. Curing agent (FX-TP-BC-PC-AD-57130): thermal cationic polymerization initiator, manufactured by Nippon Shokubai Co., Ltd.

[0139] <Production of Acid-Treated Solder Particles> Acid-treated solder particles (ST-3 or ST-7) were produced by the following procedure.

[0140] Malic acid as an acid treatment agent was dissolved in distilled water to a concentration of 1 mol / L, and dissolved gas was replaced with nitrogen by bubbling with nitrogen, thereby preparing an aqueous solution of the acid treatment agent.

[0141] Next, 50 g of an aqueous solution of the acid treatment agent was added to 50 g of solder particles (ST-3 or ST-7) in a container, and the container was closed and stirred for 20 minutes. After that, the solder particles were allowed to settle naturally, the supernatant was removed, ethanol was added, and the mixture was stirred until it became homogeneous. The same procedure was then repeated once more.

[0142] Next, after waiting for the solder particles to settle naturally, the supernatant was removed, acetone was added, and the mixture was stirred until uniform. Next, after waiting for the solder particles to settle naturally, the supernatant was removed, jER828 was added according to the formulations shown in Tables 1 to 3, and the mixture was stirred until uniform.

[0143] Next, the mixture was vacuum dried in a vacuum oven at 25° C. for 2 hours, thereby producing acid-treated solder particles.

[0144] <Production of Conductive Resin Compositions of Examples and Comparative Examples> Conductive resin compositions of Examples and Comparative Examples were produced according to the following procedure.

[0145] Solid epoxy resin (NPES907, NC-3000H) or solid phenolic resin (MEH-7851-H) was dissolved in methyl ethyl ketone to prepare a varnish (solids concentration: 60% by mass). 3,3-dimethylglutaric acid, glutaric acid, adipic acid, or pimelic acid was dissolved in methyl ethyl ketone to prepare a flux solution (solids concentration: 30% by mass). Azelaic acid or dodecanedioic acid was dissolved in methyl ethyl ketone to prepare a flux solution (solids concentration: 10% by mass). Malic acid was dissolved in ethanol to prepare a flux solution (solids concentration: 30% by mass). San-Aid SI-B3 or San-Aid SI-B4 was dissolved in methyl ethyl ketone to prepare a solution (solids concentration: 10% by mass).

[0146] When acid-treated solder particles were used, the above-prepared solder particles (acid-treated), solid epoxy resin or solid phenolic resin, and flux were mixed according to the formulations shown in Tables 1 to 3. Then, acetone was added and the mixture was stirred until homogeneous, thereby producing a varnish of a conductive resin composition.

[0147] When using solder particles without acid treatment, the solder particles (without acid treatment), solid epoxy resin or solid phenolic resin, jER828, and flux were mixed according to the formulation shown in Table 2. Acetone was then added and stirred until uniform, producing a varnish of the conductive resin composition. The numerical values ​​shown for the formulation of the conductive resin composition in each example in Tables 1 to 3 are parts by mass. Note that a curing agent was further added in Examples 8, 14, 15, 20 to 22, and Comparative Example 3.

[0148] <Production of Test Connection Structure> Test connection structures containing the conductive resin compositions of each Example and Comparative Example (hereinafter referred to as "test connection structures of each Example and Comparative Example") were produced according to the following procedure. Two types of test connection structures were produced for each Example and Comparative Example: one for evaluating solder integration and one for evaluating adhesive strength. [Step 1] For the solder integration evaluation, two substrates were prepared: a dummy wafer with Au electrodes (size 10 mm × 10 mm, electrodes 30 μm square, distance between electrode edges 30 μm) and alkali-free glass (10 mm × 10 mm). For the adhesive strength evaluation, two of the above-mentioned dummy wafers with Au electrodes were prepared. For Example 13, a dummy wafer with Au electrodes (size 10 mm × 10 mm, electrodes 50 μm square, distance between electrode edges 50 μm) was used instead of the above-mentioned dummy wafer with Au electrodes.

[0149] [Second Step] The conductive resin composition of each Example and Comparative Example was applied to a release liner using an applicator and dried for 5 minutes at 60° C. Thus, a conductive resin sheet (thickness: 5 μm) was prepared.

[0150] [Step 3] For solder integration evaluation, a dummy wafer with an Au electrode, a conductive resin sheet, and alkali-free glass were bonded together in this order at 50°C in a vacuum. For adhesive strength evaluation, a dummy wafer with an Au electrode, a conductive resin sheet, and a dummy wafer with an Au electrode were bonded together in this order at 50°C in a vacuum. The release liner was removed during bonding. This produced a laminate.

[0151] The obtained laminate was observed with an optical microscope (name "VHX-8000", manufactured by Keyence Corporation) to confirm that no air bubbles were trapped.

[0152] [Step 4] The laminate was placed in a vacuum pressure reflow machine (Model 1200 Table Top Furnace, manufactured by SST International), and after evacuation, the machine was pressurized to 4.5 atmospheres with nitrogen. Thereafter, heating was performed under the conditions of a temperature increase rate of 100°C / min, a maximum temperature of 260°C, and a holding time of 15 minutes.

[0153] For Example 13, the test connection structure for evaluating solder integration was set in a vacuum pressure reflow apparatus (named "Model 1200 Table Top Furnace", manufactured by SST International), and after evacuation, it was pressurized with nitrogen to 4.5 atmospheres, and then heated under the conditions of a temperature rise rate of 100 ° C. / min, a maximum temperature of 170 ° C., and a holding time of 1 minute. The test connection structure for evaluating adhesive strength of Example 13 was set in a vacuum pressure reflow apparatus (named "Model 1200 Table Top Furnace", manufactured by SST International), and after evacuation, it was pressurized with nitrogen to 4.5 atmospheres, and then heated under the conditions of a temperature rise rate of 100 ° C. / min, a maximum temperature of 200 ° C., and a holding time of 60 minutes.

[0154] As described above, test connection structures for evaluating solder integration and adhesive strength were produced for each of the examples and comparative examples.

[0155] <Evaluation> [Evaluation of Solder Accumulation State] For the test connection structures for evaluating the solder accumulation rate of each example and each comparative example, an optical microscope (named "VHX-8000," manufactured by Keyence Corporation) was used to observe four different visual field ranges at 900x magnification. Then, based on the following criteria, the area of ​​the area containing bubbles (void area ratio) and the solder accumulation rate of the electrodes in the visual field (electrode solder accumulation rate) were evaluated. Specifically, the electrode solder accumulation rate is expressed as a percentage of the 30 electrodes in the observed field, with electrodes whose entire surface is covered with solder being considered pass and electrodes whose entire surface or part of the electrode is exposed being considered fail. The results are shown in Tables 1 to 3. {Criteria} Level 4: The void area ratio was less than 5%, and the electrode solder accumulation rate was 95% or more. Level 3: The void area ratio was 5% or more and less than 10%, and the solder accumulation ratio of the electrode was 90% or more and less than 95%. Level 2: The void area ratio was 10% or more, and the solder accumulation ratio of the electrode was 80% or more and less than 90%. Level 1: The solder accumulation ratio of the electrode was less than 80%.

[0156] [Evaluation of Adhesion Strength] For the test connection structures for evaluating adhesion strength of each Example and Comparative Example, a die shear test was performed using a bond tester (name "DAGE4000", manufactured by Nordson Advanced Technologies) to measure shear adhesive strength. The test speed was 500 μm / sec, and the temperature condition was 260° C. The results are shown in Tables 1 to 3.

[0157]

[0158]

[0159]

[0160] 2. Test 2 Evaluation of Electrical Connection of Test Connection Structure <Production of Test Connection Structure Containing Conductive Resin Composition> A conductive resin sheet containing a conductive resin composition having the composition shown in Table 4 was produced using the procedure of Example 1, and then Example 11 was produced using the same production method as the test connection structure for adhesive strength evaluation. Example 12 was produced using the same procedure as in the production of the test connection structure for adhesive strength evaluation in Experiment 1, except that two FPC boards (electrode square 100 μm, distance between electrode ends 200 μm) were used as the two boards in the first step. The numerical values ​​shown for the formulation of the conductive resin composition for each example in Table 4 are parts by mass. Note that the dummy wafer with Au electrodes used in Example 11 is referred to as a silicon wafer substrate in Table 4.

[0161] <Evaluation> [Evaluation of Electrical Connection-1] After the test connection structure of Example 11 was embedded in resin, the laminate cross section was exposed by mechanical polishing, and the electrical connection (conductivity) of the counter electrodes was evaluated using an optical microscope (name "VHX-8000", manufactured by Keyence Corporation) according to the following criteria. The results are shown in Table 4. Level 2: Connection of the counter electrodes by solder was observed. Level 1: Connection of the counter electrodes by solder was not observed.

[0162] [Evaluation of Electrical Connection - 2] For the test connection structure of Example 12, the electrical resistance (conductivity) between the opposing electrodes was evaluated using a digital multimeter (name "PC500a", manufactured by Sanwa Electric Measurement Co., Ltd.). The electrical connection of the opposing electrodes was evaluated according to the following criteria. The results are shown in Table 4. Level 2: The electrical resistance value was a positive value (a value exceeding 0). Level 1: The electrical resistance value was 0 or less.

[0163]

[0164] The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0165] The conductive resin composition, conductive resin sheet, connection structure, and method for producing a connection structure of the present invention are suitably used, for example, in the production of electronic devices.

[0166] REFERENCE SIGNS LIST 1 conductive resin sheet 2 first substrate 4 second substrate 5 solder particles 6 laminate 10 release liner 12 first electrode 14 second electrode 15 columnar solder portion 20 connection structure 25 pressure oven

Claims

1. A conductive resin composition comprising solder particles, a resin component, and a flux, which does not contain a curing agent or, if it contains a curing agent, the content of the curing agent is less than 5 parts by mass per 100 parts by mass of the resin component, the flux being a dicarboxylic acid compound which does not contain a hydroxyl group and has 2 or more and 9 or less carbon atoms between two carboxyl groups.

2. The conductive resin composition according to claim 1, wherein the melting point of the solder particles is 150° C. or higher.

3. The conductive resin composition according to claim 2, wherein the solder particles contain Sn.

4. The conductive resin composition according to claim 1, wherein the resin component comprises a liquid resin and a solid resin.

5. A conductive resin sheet comprising the conductive resin composition according to any one of claims 1 to 4.

6. A connection structure comprising a first substrate, a second substrate arranged at a distance in the thickness direction, and an adhesive layer interposed between the first substrate and the second substrate, each of the first substrate and the second substrate having at least one electrode, a columnar solder portion being disposed between the electrode of the first substrate and the electrode of the second substrate, and the adhesive layer and the columnar solder portion being formed from the conductive resin composition according to any one of claims 1 to 4.

7. The connection structure according to claim 6, wherein the conductive resin composition has a shear adhesive strength of greater than 1.0 MPa at 260°C when cured.

8. The connection structure according to claim 6, wherein the columnar solder portion exhibits anisotropy that exists only between the electrodes.

9. A method for manufacturing a connection structure, comprising: a first step of preparing a plurality of substrates each having a plurality of electrodes arranged in a planar direction; a second step of preparing a conductive resin sheet by applying the conductive resin composition according to any one of claims 1 to 4; a third step of stacking the two substrates with the conductive resin sheet sandwiched therebetween so that the electrodes of the two substrates face each other, thereby producing a laminate; and a fourth step of heating the laminate and melting the solder particles to form columnar solder portions so as to electrically connect the electrodes of the two substrates, and hardening the conductive resin composition.

10. The method for producing a connection structure according to claim 9, wherein the fourth step is carried out in a pressure oven.

Images