Conductive material, connection structure, and method for manufacturing the connection structure

Abstract

To provide a conductive material that can effectively maintain the shape of coating of a conductive material, and can effectively improve vertical conduction reliability between electrodes.SOLUTION: A conductive material contains a thermosetting component, a plurality of solder particles, an organic acid or a salt thereof, and a compound having a hydroxy group and having a boiling point of 160°C or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a conductive material containing solder particles, and also to a connection structure using the conductive material and a method for manufacturing the connection structure. [Background technology]

[0002] Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known, and in these anisotropic conductive materials, conductive particles are dispersed in a binder resin.

[0003] The anisotropic conductive material is used to obtain various connection structures, such as a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), a connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and a connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

[0004] When electrically connecting electrodes of a flexible printed circuit board and electrodes of a glass epoxy board using the anisotropic conductive material, for example, an anisotropic conductive material containing conductive particles is placed on the glass epoxy board. Next, a flexible printed circuit board is laminated, and the resulting laminate is heated and pressurized. This hardens the anisotropic conductive material, electrically connecting the electrodes via the conductive particles and obtaining a connection structure.

[0005] As an example of the anisotropic conductive material, Patent Document 1 below describes an anisotropic conductive material containing conductive particles and a resin component that does not completely harden at the melting point of the conductive particles. Specific examples of the conductive particles include metals such as tin (Sn), indium (In), bismuth (Bi), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), gallium (Ga), silver (Ag), and thallium (Tl), as well as alloys of these metals.

[0006] Patent Document 1 describes that electrodes are electrically connected through a resin heating step in which the anisotropic conductive material is heated to a temperature higher than the melting point of the conductive particles but not yet completely hardened, and a resin component hardening step in which the resin component is hardened. Patent Document 1 also describes that mounting is performed using the temperature profile shown in Figure 8 of Patent Document 1. In Patent Document 1, the conductive particles melt within the resin component, which does not completely harden at the temperature to which the anisotropic conductive material is heated.

[0007] Patent Document 2 below discloses an adhesive tape that includes a resin layer containing a thermosetting resin, solder powder, and a curing agent, the solder powder and the curing agent being present in the resin layer. This adhesive tape is in the form of a film, not a paste.

[0008] Patent Document 2 also discloses a bonding method using the above-mentioned adhesive tape. Specifically, a first substrate, adhesive tape, second substrate, adhesive tape, and third substrate are laminated in this order from the bottom to obtain a laminate. At this time, a first electrode provided on the surface of the first substrate is opposed to a second electrode provided on the surface of the second substrate. Also, a second electrode provided on the surface of the second substrate is opposed to a third electrode provided on the surface of the third substrate. The laminate is then heated at a predetermined temperature to bond them together. This results in a connection structure. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-260131 [Patent Document 2] WO2008 / 023452A1 Summary of the Invention [Problem to be solved by the invention]

[0010] Conductive materials are sometimes used for conductive connections in electronic components such as semiconductor devices. When conductively connecting electronic components, the conductive material may be applied to the surface of the electronic component having multiple electrodes. The applied conductive material is required to electrically connect the electrodes in the vertical direction.

[0011] Conventional conductive materials such as those described in Patent Documents 1 and 2 may have low melt viscosity, which can cause excessive flow when heated by reflow or other processes. Excessive flow can prevent the conductive material applied to the surface of an electronic component from maintaining its shape (applied shape), resulting in the conductive material spreading outside the electrodes. When the conductive material spreads outside the electrodes, solder particles or conductive particles contained in the conductive material may be disposed in areas where no electrodes are formed, making it difficult to position the solder particles or conductive particles between the upper and lower electrodes to be connected. As a result, conventional conductive materials can result in reduced reliability of electrical continuity between the upper and lower electrodes to be connected.

[0012] Furthermore, when there are multiple laterally adjacent electrodes, conventional conductive materials can cause solder particles or conductive particles to be placed in areas where no electrodes are formed, resulting in electrical connection between laterally adjacent electrodes that should not be connected. As a result, conventional conductive materials can reduce the reliability of insulation between laterally adjacent electrodes that should not be connected.

[0013] An object of the present invention is to provide a conductive material that can effectively maintain the coating shape of the conductive material and effectively improve the reliability of conduction between electrodes in the vertical direction. Another object of the present invention is to provide a connection structure using the conductive material and a method for manufacturing the connection structure. [Means for solving the problem]

[0014] According to a broad aspect of the present invention, there is provided a conductive material including a thermosetting component, a plurality of solder particles, an organic acid or a salt thereof, and a compound having a hydroxyl group and a boiling point of 160°C or higher.

[0015] In a specific aspect of the conductive material according to the present invention, the compound having a hydroxyl group and a boiling point of 160° C. or higher has a hydroxyl group equivalent of 100 g / mol or higher.

[0016] In a specific aspect of the conductive material according to the present invention, the compound having a hydroxyl group and a boiling point of 160° C. or higher is a fatty acid alkylolamide or a polyhydric phenol compound.

[0017] In a specific aspect of the conductive material according to the present invention, the content of the compound having a hydroxyl group and a boiling point of 160°C or higher is 0.5% by weight or more and 2% by weight or less, based on 100% by weight of the conductive material.

[0018] In a specific aspect of the conductive material according to the present invention, the ratio of the content of the compound having a hydroxyl group and a boiling point of 160°C or higher in 100% by weight of the conductive material to the content of the organic acid or a salt thereof in 100% by weight of the conductive material is 0.5 or more and 2 or less.

[0019] In a specific aspect of the conductive material according to the present invention, the melting point of the solder particles is 180° C. or lower.

[0020] In a specific aspect of the conductive material according to the present invention, the thermosetting component includes a thermosetting compound and a thermosetting agent.

[0021] In a specific aspect of the conductive material according to the present invention, the conductive material is a conductive paste.

[0022] According to a broad aspect of the present invention, there is provided a connection structure comprising a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first connection target member and the second connection target member, wherein the material of the connection portion is the conductive material described above, and the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

[0023] In a specific aspect of the connection structure according to the present invention, when the portion where the first electrode and the second electrode face each other is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is arranged over 50% or more of the 100% area of ​​the portion where the first electrode and the second electrode face each other.

[0024] According to a broad aspect of the present invention, there is provided a method for manufacturing a connection structure, comprising the steps of: using the above-mentioned conductive material to place the conductive material on the surface of a first connection target component having a first electrode on its surface; placing a second connection target component having a second electrode on the surface of the conductive material opposite the first connection target component so that the first electrode and the second electrode face each other; and heating the conductive material to a temperature above the melting point of the solder particles to form a connection portion connecting the first connection target component and the second connection target component using the conductive material, and electrically connecting the first electrode and the second electrode by a solder portion in the connection portion.

[0025] In a particular aspect of the method for manufacturing a connection structure according to the present invention, when the opposing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, a connection structure is obtained in which the solder portion in the connection portion is arranged in more than 50% of the 100% area of ​​the opposing portion of the first electrode and the second electrode. [Effects of the Invention]

[0026] The conductive material according to the present invention includes a thermosetting component, a plurality of solder particles, an organic acid or a salt thereof, and a compound having a hydroxyl group and a boiling point of 160° C. Because the conductive material according to the present invention has the above-described configuration, it is possible to effectively maintain the applied shape of the conductive material and effectively improve the reliability of conduction between the upper and lower electrodes. [Brief explanation of the drawings]

[0027] [Figure 1]FIG. 1 is a cross-sectional view that schematically shows a connection structure obtained using a conductive material according to one embodiment of the present invention. [Figure 2] 2(a) to 2(c) are cross-sectional views illustrating the steps of an example of a method for producing a connection structure using a conductive material according to one embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view showing a modified example of the connection structure. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be described in detail below.

[0029] (Conductive materials) The conductive material according to the present invention includes a thermosetting component, a plurality of solder particles, an organic acid or a salt thereof, and a compound having a hydroxyl group and a boiling point of 160° C. or higher.

[0030] The conductive material according to the present invention has the above-mentioned configuration, and therefore the coating shape of the conductive material can be effectively maintained, and the reliability of conduction between the upper and lower electrodes can be effectively improved.

[0031] Conductive materials are sometimes used for conductive connection in electronic components such as semiconductor devices. When conductively connecting electronic components, the conductive material is sometimes applied to the surface of an electronic component having multiple electrodes using a dispenser or the like.

[0032] Conventional conductive materials can flow excessively when heated during reflow or other processes. When the conductive material flows excessively, the conductive material applied to the surface of an electronic component cannot maintain its shape (applied shape), and the conductive material may spread outside the electrodes. When the conductive material spreads outside the electrodes, solder particles contained in the conductive material may be disposed in areas where no electrodes are formed, preventing efficient placement of the solder particles between the vertical electrodes that should be connected. This may result in insufficient reliability of electrical connection between the vertical electrodes. Furthermore, when solder particles are disposed in areas where no electrodes are formed, horizontally adjacent electrodes that should not be connected may be electrically connected, preventing sufficient reliability of insulation between the horizontally adjacent electrodes.

[0033] The inventors have found that by using a specific conductive material, flux activity can be exerted at a relatively low temperature, the oxide film on the surface of the solder particles can be removed, and the solder particles can be connected to each other, thereby effectively maintaining the coated shape of the conductive material. In this invention, even when the conductive material is heated by reflow or the like, the coated shape of the conductive material can be effectively maintained, the solder particles can be efficiently arranged between the electrodes to be connected, and the conductivity reliability and insulation reliability can be effectively improved.

[0034] Furthermore, in the present invention, when the electrodes are electrically connected, multiple solder particles tend to gather between the upper and lower opposing electrodes, allowing multiple solder particles to be arranged on the electrodes (lines). Furthermore, some of the multiple solder particles are less likely to be arranged between horizontal electrodes that should not be connected, significantly reducing the amount of solder particles arranged between horizontal electrodes that should not be connected. As a result, in the present invention, the amount of solder remaining between horizontal electrodes that should not be connected can be reduced.

[0035] In the present invention, the use of a specific conductive material contributes greatly to achieving the above-mentioned effects. In the present invention, the use of a specific conductive material that contains an organic acid or a salt thereof and a compound that has a hydroxyl group and a boiling point of 160°C or higher contributes greatly to achieving the above-mentioned effects.

[0036] Furthermore, the present invention can prevent misalignment between electrodes. When a second member to be connected is placed on a first member to be connected, which has a conductive material disposed on its upper surface, even if the electrodes of the first member to be connected and the electrodes of the second member to be connected are misaligned, the misalignment can be corrected to connect the electrodes (self-alignment effect).

[0037] From the viewpoint of disposing the solder on the electrodes more efficiently, the conductive material is preferably liquid at 25°C and is preferably a conductive paste. The conductive material is preferably a conductive paste at 25°C.

[0038] From the viewpoint of disposing the solder on the electrode more efficiently, the viscosity (η25) of the conductive material at 25°C is preferably 30 Pa s or more, more preferably 50 Pa s or more, and is preferably 400 Pa s or less, more preferably 300 Pa s or less. The viscosity (η25) can be adjusted appropriately by changing the types and amounts of the blended components.

[0039] The viscosity (η25) can be measured, for example, using an E-type viscometer ("TVE22L" manufactured by Toki Sangyo Co., Ltd.) under conditions of 25° C. and 5 rpm.

[0040] The conductive material can be used as a conductive paste, a conductive film, or the like. The conductive paste is preferably an anisotropic conductive paste, and the conductive film is preferably an anisotropic conductive film. From the viewpoint of more efficiently disposing the solder on the electrodes, the conductive material is preferably a conductive paste. The conductive material is suitably used for electrically connecting electrodes. The conductive material is preferably a circuit connecting material.

[0041] Each component contained in the conductive material will be explained below. In this specification, "(meth)acrylic" means either or both of "acrylic" and "methacrylic".

[0042] (solder particles) The solder particles are formed of solder at both the center and the outer surface. The solder particles are particles in which both the center and the outer surface are solder. If conductive particles comprising a base particle formed from a material other than solder and a solder portion arranged on the surface of the base particle are used instead of the solder particles, the conductive particles are less likely to gather on the electrode. Furthermore, since the conductive particles have low solder bonding between the conductive particles, the conductive particles that have moved onto the electrode tend to easily move outside the electrode, and the effect of suppressing misalignment between the electrodes also tends to be reduced.

[0043] The solder is preferably a metal (low melting point metal) having a melting point of 450°C or less. The solder particles are preferably metal particles (low melting point metal particles) having a melting point of 450°C or less. The low melting point metal particles are particles containing a low melting point metal. The low melting point metal refers to a metal having a melting point of 450°C or less. The melting point of the low melting point metal is preferably 300°C or less, more preferably 160°C or less. The solder is preferably a low melting point solder having a melting point of less than 150°C.

[0044] The melting point of the solder particles is preferably 180° C. or less, more preferably 150° C. or less. The melting point of the solder particles may be higher than 180° C. When the melting point of the solder particles is equal to or less than the upper limit, thermal degradation of the conductive material can be more effectively suppressed.

[0045] The melting point of the solder particles can be determined by differential scanning calorimetry (DSC). Examples of DSC devices include the "EXSTAR DSC7020" manufactured by SII Corporation.

[0046] Furthermore, the solder particles preferably contain tin. The tin content of the solder particles, based on 100% by weight of the metals contained in the solder particles, is preferably 30% by weight or more, more preferably 40% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the tin content in the solder particles is equal to or greater than the lower limit, the electrical continuity reliability and connection reliability between the solder portion and the electrode are further improved.

[0047] The tin content can be measured using a high-frequency inductively coupled plasma atomic emission spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer ("EDX-800HS" manufactured by Shimadzu Corporation).

[0048] By using the solder particles, the solder melts and bonds to the electrodes, and the solder portion establishes electrical continuity between the electrodes. For example, the solder portion and the electrodes are more likely to have surface contact rather than point contact, which reduces connection resistance. Furthermore, the use of the solder particles increases the bonding strength between the solder portion and the electrodes, making it even less likely for the solder portion and the electrodes to peel off, thereby further improving the reliability of electrical continuity and connection.

[0049] The low-melting-point metal constituting the solder particles is not particularly limited. The low-melting-point metal is preferably tin or an alloy containing tin. Examples of such alloys include tin-silver alloys, tin-copper alloys, tin-silver-copper alloys, tin-bismuth alloys, tin-zinc alloys, and tin-indium alloys. Because of their excellent wettability with electrodes, the low-melting-point metal is preferably tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, or a tin-indium alloy. The low-melting-point metal is more preferably a tin-bismuth alloy or a tin-indium alloy.

[0050] The solder particles are preferably filler metals with a liquidus temperature of 450°C or lower, based on JIS Z3001: Welding Terminology. Examples of the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium, etc. Low-melting-point, lead-free tin-indium (117°C eutectic) or tin-bismuth (139°C eutectic) are preferred. In other words, the solder particles are preferably lead-free, and contain tin and indium, or tin and bismuth.

[0051] To further increase the bond strength between the solder part and the electrode, the solder particles may contain metals such as nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, molybdenum, and palladium. Furthermore, from the viewpoint of further increasing the bond strength between the solder part and the electrode, the solder particles preferably contain nickel, copper, antimony, aluminum, or zinc. To further increase the bond strength between the solder part and the electrode, the content of these metals is preferably 0.0001 wt % or more and preferably 1 wt % or less based on 100 wt % of the metals contained in the solder particles.

[0052] The particle diameter of the solder particles is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more, and is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. When the particle diameter of the solder particles is equal to or greater than the lower limit and equal to or less than the upper limit, the solder particles can be arranged on the electrode more efficiently. The particle diameter of the solder particles is particularly preferably 3 μm or more and 10 μm or less.

[0053] The particle size of the solder particles is preferably an average particle size, more preferably a number average particle size, which can be determined, for example, by observing 50 random solder particles with an electron microscope or an optical microscope and calculating the average particle size of each solder particle, or by performing laser diffraction particle size distribution measurement.

[0054] The coefficient of variation (CV value) of the particle diameter of the solder particles is preferably 5% or more, more preferably 10% or more, and preferably 40% or less, more preferably 30% or less. When the coefficient of variation of the particle diameter of the solder particles is equal to or greater than the lower limit and equal to or less than the upper limit, the solder can be more efficiently arranged on the electrode. However, the CV value of the particle diameter of the solder particles may be less than 5%.

[0055] The coefficient of variation (CV value) can be measured as follows.

[0056] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of solder particle diameter Dn: Average particle diameter of solder particles

[0057] The shape of the solder particles is not particularly limited, and may be spherical or may be a non-spherical shape such as flat.

[0058] The content of the solder particles in 100% by weight of the conductive material is preferably 50% by weight or more, more preferably 55% by weight or more, even more preferably 60% by weight or more, particularly preferably 65% ​​by weight or more, and most preferably 70% by weight or more. The content of the solder particles in 100% by weight of the conductive material is preferably 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less, and particularly preferably 75% by weight or less. When the content of the solder particles is equal to or greater than the lower limit, the applied shape of the conductive material can be more effectively maintained. When the content of the solder particles is equal to or greater than the lower limit and equal to or less than the upper limit, the solder particles can be more efficiently arranged on the electrodes, making it easier to arrange a large amount of solder between the electrodes and further improving the electrical conductivity reliability. From the viewpoint of further improving the electrical conductivity reliability, a higher content of the solder particles is preferable.

[0059] (thermosetting component) The conductive material includes a thermosetting component. The conductive material may include a thermosetting compound and a thermosetting agent as the thermosetting components. In order to cure the conductive material more satisfactorily, the conductive material preferably includes a thermosetting compound and a thermosetting agent as the thermosetting components. In order to cure the conductive material more satisfactorily, the conductive material more preferably includes a thermosetting compound, a thermosetting agent, and a curing accelerator as the thermosetting components.

[0060] (Thermosetting component: thermosetting compound) The thermosetting compound is not particularly limited. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth)acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. From the viewpoint of further improving the curability and viscosity of the conductive material, more effectively increasing the conduction reliability, and more effectively increasing the insulation reliability, epoxy compounds or episulfide compounds are preferred, and epoxy compounds are more preferred. The thermosetting compound preferably contains an epoxy compound. Only one type of the thermosetting compound may be used, or two or more types may be used in combination.

[0061] The epoxy compound is a compound having at least one epoxy group. Examples of the epoxy compound include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, phenol novolac type epoxy compounds, biphenyl type epoxy compounds, biphenyl novolac type epoxy compounds, biphenol type epoxy compounds, naphthalene type epoxy compounds, fluorene type epoxy compounds, phenol aralkyl type epoxy compounds, naphthol aralkyl type epoxy compounds, dicyclopentadiene type epoxy compounds, anthracene type epoxy compounds, epoxy compounds having an adamantane skeleton, epoxy compounds having a tricyclodecane skeleton, naphthylene ether type epoxy compounds, and epoxy compounds having a triazine nucleus in the skeleton. The epoxy compounds may be used alone or in combination of two or more.

[0062] The epoxy compound is liquid or solid at room temperature (23°C). If the epoxy compound is solid at room temperature, the melting temperature of the epoxy compound is preferably equal to or lower than the melting point of the solder particles. By using the preferred epoxy compound, the viscosity is high when the connection target components are bonded together, and misalignment between the first connection target component and the second connection target component can be suppressed when acceleration is applied due to impact during transport, etc. Furthermore, the heat generated during curing can significantly reduce the viscosity of the conductive material, allowing the aggregation of the solder particles to proceed efficiently.

[0063] From the viewpoint of more effectively improving insulation reliability and more effectively improving conduction reliability, it is preferable that the thermosetting component contains an epoxy compound, and it is preferable that the thermosetting compound contains an epoxy compound.

[0064] From the viewpoint of disposing the solder particles on the electrodes more effectively, the thermosetting compound preferably includes a thermosetting compound having a polyether skeleton.

[0065] Examples of the thermosetting compound having a polyether skeleton include a compound having glycidyl ether groups at both ends of an alkyl chain having 3 to 12 carbon atoms, and a polyether epoxy compound having a polyether skeleton having 2 to 4 carbon atoms and a structural unit in which 2 to 10 polyether skeletons are bonded consecutively.

[0066] From the viewpoint of more effectively increasing the heat resistance of the cured product, the thermosetting compound preferably includes a thermosetting compound having an isocyanuric skeleton.

[0067] Examples of the thermosetting compound having an isocyanuric skeleton include triisocyanurate-type epoxy compounds, such as the TEPIC series (TEPIC-G, TEPIC-S, TEPIC-SS, TEPIC-HP, TEPIC-L, TEPIC-PAS, TEPIC-VL, TEPIC-UC) manufactured by Nissan Chemical Industries, Ltd.

[0068] The content of the thermosetting compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, and preferably 99% by weight or less, more preferably 98% by weight or less, even more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the thermosetting compound is above the above lower limit and below the above upper limit, the solder particles can be more efficiently arranged on the electrodes, more effectively improving the insulation reliability between the electrodes and more effectively improving the conduction reliability between the electrodes. From the viewpoint of more effectively improving impact resistance, the content of the thermosetting compound is preferably high.

[0069] The content of the epoxy compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, and preferably 99% by weight or less, more preferably 98% by weight or less, even more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the epoxy compound is above the above lower limit and below the above upper limit, solder particles can be more efficiently arranged on the electrodes, more effectively improving the insulation reliability between the electrodes and more effectively improving the conduction reliability between the electrodes. From the viewpoint of further improving impact resistance, a higher content of the epoxy compound is preferable.

[0070] (Thermosetting component: thermosetting agent) The thermosetting agent is not particularly limited. The thermosetting agent thermally cures the thermosetting compound. Examples of the thermosetting agent include imidazole curing agents, amine curing agents, phenolic curing agents, thiol curing agents such as polythiol curing agents, acid anhydride curing agents, thermal cationic initiators (thermal cationic curing agents), and thermal radical generators. The thermosetting agent may be used alone or in combination of two or more.

[0071] From the viewpoint of enabling the conductive material to be cured more quickly at low temperatures, the heat curing agent is preferably an imidazole curing agent, a thiol curing agent, or an amine curing agent. Furthermore, from the viewpoint of improving storage stability when the heat curing compound and the heat curing agent are mixed, the heat curing agent is preferably a latent curing agent. The latent curing agent is preferably a latent imidazole curing agent, a latent thiol curing agent, or a latent amine curing agent. The heat curing agent may be coated with a polymeric substance such as a polyurethane resin or a polyester resin.

[0072] The imidazole curing agent is not particularly limited, and examples of the imidazole curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroximide, 2-methyl-4-methylimidazole ... Examples of the imidazole compounds include 2-amino-4-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2-para-toluyl-4-methyl-5-hydroxymethylimidazole, 2-meta-toluyl-4-methyl-5-hydroxymethylimidazole, 2-meta-toluyl-4,5-dihydroxymethylimidazole, and 2-para-toluyl-4,5-dihydroxymethylimidazole, in which the hydrogen at the 5-position of 1H-imidazole is substituted with a hydroxymethyl group and the hydrogen at the 2-position with a phenyl group or a toluyl group.

[0073] The thiol curing agent is not particularly limited, and examples of the thiol curing agent include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate.

[0074] The amine curing agent is not particularly limited, and examples of the amine curing agent include hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro[5.5]undecane, bis(4-aminocyclohexyl)methane, metaphenylenediamine, and diaminodiphenyl sulfone.

[0075] The acid anhydride curing agent is not particularly limited, and any acid anhydride that is used as a curing agent for thermosetting compounds such as epoxy compounds can be widely used. Examples of the acid anhydride curing agent include phthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, anhydrides of phthalic acid derivatives, maleic anhydride, nadic anhydride, methylnadic anhydride, glutaric anhydride, succinic anhydride, glycerin bistrimellitic anhydride monoacetate, and ethylene glycol bistrimellitic anhydride, bifunctional acid anhydride curing agents such as trimellitic anhydride, and tetrafunctional or higher acid anhydride curing agents such as pyromellitic anhydride, benzophenonetetracarboxylic anhydride, methylcyclohexenetetracarboxylic anhydride, and polyazelaic anhydride.

[0076] The thermal cationic initiator is not particularly limited. Examples of the thermal cationic initiator include an iodonium cationic curing agent, an oxonium cationic curing agent, and a sulfonium cationic curing agent. Examples of the iodonium cationic curing agent include bis(4-tert-butylphenyl)iodonium hexafluorophosphate. Examples of the oxonium cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

[0077] The thermal radical generator is not particularly limited. Examples of the thermal radical generator include azo compounds and organic peroxides. Examples of the azo compounds include azobisisobutyronitrile (AIBN). Examples of the organic peroxides include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

[0078] The reaction initiation temperature of the thermosetting agent is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and preferably 250°C or lower, more preferably 200°C or lower, even more preferably 150°C or lower, and particularly preferably 140°C or lower. When the reaction initiation temperature of the thermosetting agent is above the above lower limit and below the above upper limit, the solder particles are more efficiently arranged on the electrodes. The reaction initiation temperature of the thermosetting agent is particularly preferably 80°C or higher and 140°C or lower.

[0079] From the viewpoint of more efficiently disposing the solder particles on the electrodes, the reaction initiation temperature of the thermosetting agent is preferably higher than the melting point of the solder particles, more preferably by 5°C or more, and even more preferably by 10°C or more.

[0080] The reaction initiation temperature of the heat curing agent means the temperature at which the exothermic peak begins to rise in DSC.

[0081] The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, and preferably 200 parts by weight or less, more preferably 100 parts by weight or less, and even more preferably 75 parts by weight or less, relative to 100 parts by weight of the thermosetting compound. When the content of the thermosetting agent is equal to or greater than the lower limit, the conductive material can be easily cured sufficiently. When the content of the thermosetting agent is equal to or less than the upper limit, excess thermosetting agent that is not involved in curing is less likely to remain after curing, and the heat resistance of the cured product is further improved.

[0082] (Thermosetting component: Curing accelerator) The conductive material may contain a curing accelerator. The curing accelerator is not particularly limited. The curing accelerator preferably acts as a curing catalyst in the reaction between the thermosetting compound and the thermosetting agent. The curing accelerator preferably acts as a curing catalyst in the reaction with the thermosetting compound. Only one type of curing accelerator may be used, or two or more types may be used in combination.

[0083] Examples of the curing accelerator include phosphonium salts, tertiary amines, tertiary amine salts, quaternary onium salts, tertiary phosphines, crown ether complexes, and phosphonium ylides. Specific examples of the curing accelerator include imidazole compounds, isocyanurates of imidazole compounds, dicyandiamide, derivatives of dicyandiamide, melamine compounds, derivatives of melamine compounds, diaminomaleonitrile, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, bis(hexamethylene)triamine, triethanolamine, diaminodiphenylmethane, amine compounds such as organic acid dihydrazides, 1,8-diazabicyclo[5,4,0]undecene-7, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, boron trifluoride, and organic phosphorus compounds such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine.

[0084] The phosphonium salt is not particularly limited, and examples of the phosphonium salt include tetra-normal-butylphosphonium bromide, tetra-normal-butylphosphonium OO diethyldithiophosphate, methyltributylphosphonium dimethylphosphate, tetra-normal-butylphosphonium benzotriazole, tetra-normal-butylphosphonium tetrafluoroborate, and tetra-normal-butylphosphonium tetraphenylborate.

[0085] The content of the curing accelerator is appropriately selected so that the thermosetting compound is cured well. The content of the curing accelerator per 100 parts by weight of the thermosetting compound is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, and preferably 10 parts by weight or less, more preferably 8 parts by weight or less. When the content of the curing accelerator is equal to or more than the lower limit and equal to or less than the upper limit, the thermosetting compound can be cured well.

[0086] (organic acid or its salt) The conductive material includes an organic acid or a salt thereof. The organic acid or the salt thereof is not particularly limited. The conductive material may include only an organic acid, only a salt of an organic acid, or both an organic acid and a salt of the organic acid.

[0087] Examples of the organic acid include lactic acid, stearic acid, glutamic acid, glutaric acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, malic acid, cycloaliphatic carboxylic acids such as cyclohexylcarboxylic acid and 1,4-cyclohexyldicarboxylic acid, aromatic carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid, and phosphate esters.

[0088] Examples of the salt of the organic acid include the salts of the organic acids described above.

[0089] From the viewpoint of more effectively maintaining the coating shape of the conductive material and more effectively improving the reliability of conduction between the upper and lower electrodes, the organic acid or salt thereof is preferably a flux. The conductive material preferably contains a flux as the organic acid or salt thereof.

[0090] The content of the organic acid or its salt in 100% by weight of the conductive material is preferably 0.5% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. When the content of the organic acid or its salt is equal to or more than the lower limit and equal to or less than the upper limit, oxide films are less likely to form on the surfaces of the solder and electrodes, and further, oxide films formed on the surfaces of the solder and electrodes can be removed more effectively.

[0091] (Flux) The conductive material may contain a flux. The flux is not particularly limited. A flux generally used for solder joints or the like may be used as the flux. The flux is preferably the organic acid or a salt thereof described above. The flux may contain a compound other than the organic acid or the salt thereof described above.

[0092] Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an amine compound, an organic acid, and pine resin. Only one type of the flux may be used, or two or more types may be used in combination.

[0093] Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux is preferably an organic acid having two or more carboxyl groups or pine resin. The flux may be an organic acid having two or more carboxyl groups or pine resin. The use of an organic acid or pine resin having two or more carboxyl groups further increases the reliability of conduction between electrodes.

[0094] Examples of the organic acid having two or more carboxyl groups include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0095] Examples of the amine compound include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzimidazole, benzotriazole, and carboxybenzotriazole.

[0096] The rosin is a rosin containing abietic acid as a main component. Examples of the rosin include abietic acid and acrylic-modified rosin. The flux is preferably a rosin, and more preferably abietic acid. Use of this preferred flux can further effectively improve the reliability of electrical conduction between electrodes.

[0097] The activation temperature (melting point) of the flux is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and preferably 200°C or lower, more preferably 190°C or lower, even more preferably 160°C or lower, even more preferably 150°C or lower, and even more preferably 140°C or lower. When the activation temperature of the flux is above the lower limit and below the upper limit, the flux effect is more effectively exerted, and the solder is more efficiently disposed on the electrode. The activation temperature (melting point) of the flux is preferably 80°C or higher and 190°C or lower. It is particularly preferably 80°C or higher and 140°C or lower.

[0098] Examples of the flux having an active temperature (melting point) of 80°C or higher and 190°C or lower include dicarboxylic acids such as succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), pimelic acid (melting point 104°C), and suberic acid (melting point 142°C), as well as benzoic acid (melting point 122°C) and malic acid (melting point 130°C).

[0099] The boiling point of the flux is preferably 200°C or lower.

[0100] From the viewpoint of more efficiently disposing the solder particles on the electrodes, the melting point of the flux is preferably higher than the melting point of the solder particles, more preferably by 5°C or more, and even more preferably by 10°C or more.

[0101] From the viewpoint of more efficiently disposing the solder particles on the electrodes, the melting point of the flux is preferably higher than the reaction initiation temperature of the thermosetting agent, more preferably by 5°C or more, and even more preferably by 10°C or more.

[0102] The flux may be dispersed in the conductive material or may be attached to the surface of the solder particles.

[0103] Because the melting point of the flux is higher than that of the solder particles, the solder particles can be efficiently condensed on the electrode. This is because, when heat is applied during joining, the electrode formed on the connection target component has a higher thermal conductivity than the surrounding area of ​​the connection target component, resulting in a faster temperature rise in the electrode. When the temperature exceeds the melting point of the solder particles, the interior of the solder particles melts, but the oxide film formed on the surface is not removed because it has not yet reached the melting point (activation temperature) of the flux. In this state, the temperature of the electrode reaches the melting point (activation temperature) of the flux first, so the oxide film on the surface of the solder particles that have migrated to the electrode is preferentially removed, allowing the solder particles to wet and spread over the electrode surface. This allows the solder particles to be efficiently condensed on the electrode.

[0104] The flux is preferably one that releases cations when heated, as the use of a flux that releases cations when heated allows the solder particles to be arranged on the electrodes more efficiently.

[0105] The flux that releases cations when heated includes the above-mentioned thermal cationic initiator (thermal cationic curing agent).

[0106] From the viewpoint of more efficiently disposing solder particles on the electrodes, more effectively improving insulation reliability, and more effectively improving conduction reliability, it is preferable that the flux be a salt of an acid compound and a basic compound.

[0107] The acid compound is preferably an organic compound having a carboxyl group. Examples of the acid compound include aliphatic carboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, and malic acid; alicyclic carboxylic acids such as cyclohexylcarboxylic acid and 1,4-cyclohexyldicarboxylic acid; and aromatic carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid. From the viewpoints of more efficiently disposing solder particles on electrodes, more effectively improving insulation reliability, and more effectively improving conduction reliability, the acid compound is preferably glutaric acid, cyclohexylcarboxylic acid, or adipic acid.

[0108] The basic compound is preferably an organic compound having an amino group. Examples of the basic compound include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, 4-tert-butylbenzylamine, N-methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N,N-dimethylbenzylamine, imidazole compounds, and triazole compounds. From the viewpoints of more efficiently disposing solder particles on electrodes, more effectively improving insulation reliability, and more effectively improving conduction reliability, the basic compound is preferably benzylamine.

[0109] The content of the flux is preferably 0.5 wt % or more, preferably 30 wt % or less, and more preferably 25 wt % or less, based on 100 wt % of the conductive material. The conductive material may be free of flux. When the content of the flux is equal to or greater than the lower limit and equal to or less than the upper limit, oxide films are less likely to form on the surfaces of the solder and electrodes, and oxide films formed on the surfaces of the solder and electrodes can be removed more effectively.

[0110] (Compounds with a hydroxyl group and a boiling point of 160°C or higher) The conductive material includes a compound (hereinafter, sometimes referred to as compound A) that has a hydroxyl group and a boiling point of 160°C or higher. Compound A is different from the organic acid or its salt and the flux described above. Compound A is a compound separate from the organic acid or its salt and the flux described above.

[0111] The compound A has a hydroxyl group. The compound A has a boiling point of 160°C or higher. The compound A preferably has a boiling point of 160°C or higher, more preferably 250°C or higher. The upper limit of the boiling point of the compound A is not particularly limited. The boiling point of the compound A may be 500°C or lower. When the boiling point of the compound A is equal to or higher than the lower limit and equal to or lower than the upper limit, the coating shape of the conductive material can be more effectively maintained, and the electrical conductivity reliability between the upper and lower electrodes can be more effectively improved.

[0112] In the present invention, the conductive material contains the organic acid or its salt (flux) and the compound A. By including the organic acid or its salt and the compound A in the conductive material, flux activity can be exhibited at a relatively low temperature. When flux activity is exhibited at a relatively low temperature, the oxide film on the surface of the solder particles contained in the conductive material is removed at a relatively low temperature, and the solder particles are bonded together. As a result, the applied shape of the conductive material can be more effectively maintained. In the present invention, even when the conductive material is heated by reflow or the like, the solder particles are bonded together at a relatively low temperature. Therefore, even when the thermosetting component or the like melts, the applied shape of the conductive material can be more effectively maintained, and the solder particles can be more efficiently arranged between the electrodes to be connected, thereby more effectively improving the conductivity reliability and insulation reliability.

[0113] The hydroxyl equivalent of the compound A is preferably 100 g / mol or more, more preferably 150 g / mol or more. There is no particular upper limit to the hydroxyl equivalent of the compound A. The hydroxyl equivalent of the compound A may be 500 g / mol or less. When the hydroxyl equivalent of the compound A is equal to or more than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the coating shape of the conductive material can be more effectively maintained, and the electrical conductivity reliability between the upper and lower electrodes can be more effectively improved.

[0114] The hydroxyl equivalent of the compound A can be calculated from the hydroxyl value of the compound A. The hydroxyl equivalent of the compound A and the hydroxyl value of the compound A satisfy the relationship of the following formula (1).

[0115] Hydroxyl equivalent of compound A = 56110 / hydroxyl value of compound A Formula (1)

[0116] The hydroxyl value of the compound A can be measured, for example, by a hydroxyl value quantitative analysis method (JIS K 0070).

[0117] The compound A is not particularly limited. Examples of the compound A include fatty acid alkylolamides, polyhydric phenol compounds, and polyhydric alcohols. The compound A may be used alone or in combination of two or more.

[0118] From the viewpoint of more effectively maintaining the coating shape of the conductive material and more effectively increasing the reliability of conduction between the upper and lower electrodes, the compound A is preferably a fatty acid alkylolamide or a polyhydric phenol compound, and more preferably a fatty acid alkylolamide.

[0119] The fatty acid alkylolamide is not particularly limited. Examples of the fatty acid alkylolamide include lauric acid monoethanolamide, lauric acid isopropanolamide, lauric acid diethanolamide, palmitic acid monoethanolamide, palmitic acid diethanolamide, stearic acid monoethanolamide, stearic acid diethanolamide, coconut oil fatty acid monoethanolamide, coconut oil fatty acid diethanolamide, palm kernel fatty acid monoisopropanolamide, and palm kernel fatty acid diethanolamide. The fatty acid alkylolamide may be used alone or in combination of two or more.

[0120] From the viewpoint of more effectively maintaining the coating shape of the conductive material and more effectively improving the reliability of conduction between the upper and lower electrodes, the fatty acid alkylolamide is preferably stearic acid monoethanolamide or lauric acid monoethanolamide, and more preferably stearic acid monoethanolamide.

[0121] The polyhydric phenol compound is not particularly limited. Examples of the polyhydric phenol compound include benzenediols such as catechol, resorcinol, and hydroquinone, and benzenetriols such as hydroxyquinol, phloroglucinol, and pyrogallol. The polyhydric phenol compound may be used alone or in combination of two or more.

[0122] From the viewpoint of more effectively maintaining the coating shape of the conductive material and more effectively improving the reliability of conduction between the upper and lower electrodes, the polyhydric phenol compound is preferably resorcinol or catechol, and more preferably resorcinol.

[0123] The content of the compound A in 100% by weight of the conductive material is preferably 0.5% by weight or more, more preferably 1% by weight or more, and preferably 2% by weight or less, more preferably 1.2% by weight or less. When the content of the compound A is equal to or more than the lower limit and equal to or less than the upper limit, the coating shape of the conductive material can be more effectively maintained, and the reliability of conduction between the upper and lower electrodes can be more effectively improved.

[0124] The ratio of the content of compound A in 100% by weight of the conductive material to the content of the organic acid or its salt in 100% by weight of the conductive material (content of compound A in 100% by weight of the conductive material / content of organic acid or its salt in 100% by weight of the conductive material) is preferably 0.5 or more, more preferably 0.8 or more, and preferably 2 or less, more preferably 1.5 or less. When the ratio (content of compound A in 100% by weight of the conductive material / content of organic acid or its salt in 100% by weight of the conductive material) is equal to or greater than the above lower limit and equal to or less than the above upper limit, the coating shape of the conductive material can be maintained more effectively, and the electrical conductivity reliability between the upper and lower electrodes can be more effectively improved.

[0125] (filler) The conductive material according to the present invention may contain a filler. The filler may be an organic filler or an inorganic filler. When the conductive material contains a filler, the solder particles can be uniformly aggregated on all electrodes of the substrate.

[0126] The conductive material preferably does not contain the filler or contains 5% by weight or less of the filler. When the thermosetting compound is used, the lower the filler content, the easier it is for the solder particles to move onto the electrodes.

[0127] The content of the filler in 100% by weight of the conductive material is preferably 0% by weight (not contained) or more, and preferably 5% by weight or less, more preferably 2% by weight or less, and even more preferably 1% by weight or less. When the content of the filler is equal to or more than the above lower limit and equal to or less than the above upper limit, the solder particles are more uniformly arranged on the electrode.

[0128] (Other ingredients) The conductive material may contain various additives, as needed, such as a filler, an extender, a softener, a plasticizer, a thixotropic agent, a leveling agent, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and a flame retardant.

[0129] (Connection structure and method for manufacturing the connection structure) The connection structure according to the present invention comprises a first connection-target member having a first electrode on its surface, a second connection-target member having a second electrode on its surface, and a connection portion connecting the first connection-target member and the second connection-target member. In the connection structure according to the present invention, the material of the connection portion is the conductive material described above. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

[0130] A method for manufacturing a connection structure according to the present invention comprises the steps of: using the above-described conductive material to place the conductive material on the surface of a first connection target member having a first electrode on its surface; and placing a second connection target member having a second electrode on its surface, on the surface of the conductive material opposite to the first connection target member, so that the first electrode faces the second electrode. A method for manufacturing a connection structure according to the present invention comprises the steps of heating the conductive material to a temperature equal to or higher than the melting point of the solder particles to form a connection section connecting the first connection target member and the second connection target member using the conductive material, and electrically connecting the first electrode and the second electrode with a solder section in the connection section.

[0131] The connection structure and the method for manufacturing the connection structure according to the present invention use a specific conductive material, which makes it easier for solder particles to gather between the first electrode and the second electrode, allowing the solder particles to be efficiently arranged on the electrodes (lines). Furthermore, some of the solder particles are less likely to be arranged in areas (spaces) where no electrodes are formed, significantly reducing the amount of solder particles arranged in areas where no electrodes are formed. This improves the reliability of electrical continuity between the first electrode and the second electrode. Furthermore, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, thereby improving insulation reliability.

[0132] Furthermore, in order to efficiently arrange the solder particles on the electrodes and significantly reduce the amount of solder particles arranged in areas where no electrodes are formed, it is preferable to use a conductive paste rather than a conductive film as the conductive material.

[0133] The thickness of the solder between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, and preferably 100 μm or less, more preferably 80 μm or less. The solder wetted area on the surface of the electrode (the area in contact with the solder out of 100% of the exposed area of ​​the electrode) is preferably 50% or more, more preferably 70% or more, and preferably 100% or less.

[0134] In the method for manufacturing a connection structure according to the present invention, it is preferable that no pressure is applied in the process of arranging the second member to be connected and the process of forming the connection portion, and that the weight of the second member to be connected is applied to the conductive material. In the method for manufacturing a connection structure according to the present invention, it is preferable that no pressure exceeding the force of the weight of the second member to be connected is applied to the conductive material in the process of arranging the second member to be connected and the process of forming the connection portion. In these cases, the uniformity of the amount of solder in the multiple solder portions can be further improved. Furthermore, the thickness of the solder portions can be more effectively increased, making it easier for multiple solder particles to gather between electrodes, and allowing the multiple solder particles to be more efficiently arranged on the electrodes (lines). Furthermore, it is difficult for some of the multiple solder particles to be arranged in areas (spaces) where no electrodes are formed, and the amount of solder in the solder particles arranged in areas where no electrodes are formed can be further reduced. Therefore, the reliability of conductivity between electrodes can be further improved. Moreover, electrical connection between laterally adjacent electrodes that should not be connected can be more effectively prevented, thereby further improving insulation reliability.

[0135] Furthermore, using a conductive paste instead of a conductive film makes it easier to adjust the thickness of the connection and solder joints by adjusting the amount of conductive paste applied. On the other hand, with a conductive film, changing or adjusting the thickness of the connection requires preparing conductive films of different thicknesses or conductive films of a specific thickness. Furthermore, compared with a conductive paste, with a conductive film, the melt viscosity of the conductive film cannot be sufficiently reduced at the melting temperature of the solder, which tends to inhibit the aggregation of solder particles.

[0136] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0137] FIG. 1 is a cross-sectional view that schematically shows a connection structure obtained using a conductive material according to one embodiment of the present invention.

[0138] The connection structure 1 shown in FIG. 1 includes a first connection-target member 2, a second connection-target member 3, and a connection portion 4 connecting the first connection-target member 2 and the second connection-target member 3. The connection portion 4 is formed from the conductive material described above. In this embodiment, the conductive material includes a thermosetting component and solder particles. The thermosetting component includes a thermosetting compound and a thermosetting agent. In this embodiment, a conductive paste is used as the conductive material.

[0139] The connection portion 4 has a solder portion 4A in which a plurality of solder particles are gathered and joined together, and a cured portion 4B in which a thermosetting compound is thermally cured.

[0140] The first connection target member 2 has a plurality of first electrodes 2a on its surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on its surface (lower surface). The first electrodes 2a and the second electrodes 3a are electrically connected by the solder portion 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by the solder portion 4A. In the connection portion 4, no solder particles are present in a region (hardened portion 4B) other than the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In a region (hardened portion 4B) other than the solder portion 4A, no solder particles are present apart from the solder portion 4A. In a small amount, solder particles may be present in a region (hardened portion 4B) other than the solder portion 4A gathered between the first electrode 2a and the second electrode 3a.

[0141] As shown in FIG. 1 , in the connection structure 1, multiple solder particles gather between the first electrode 2a and the second electrode 3a. After the multiple solder particles melt, the molten solder particles spread over the surface of the electrodes and then solidify, forming a solder portion 4A. This increases the contact area between the solder portion 4A and the first electrode 2a and between the solder portion 4A and the second electrode 3a. In other words, the use of solder particles increases the contact area between the solder portion 4A and the first electrode 2a and between the solder portion 4A and the second electrode 3a compared to the use of conductive particles whose conductive outer surface is made of a metal such as nickel, gold, or copper. This also increases the electrical continuity and connection reliability of the connection structure 1. Note that when the conductive material contains flux, the flux generally gradually deactivates when heated.

[0142] In the connection structure 1 shown in FIG. 1, all of the solder portions 4A are located in the opposing region between the first and second electrodes 2a, 3a. The modified connection structure 1X shown in FIG. 3 differs from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. The connection portion 4X has a solder portion 4XA and a hardened portion 4XB. Like the connection structure 1X, most of the solder portion 4XA is located in the opposing region between the first and second electrodes 2a, 3a, and some of the solder portion 4XA may extend laterally beyond the opposing region between the first and second electrodes 2a, 3a. The solder portion 4XA extending laterally beyond the opposing region between the first and second electrodes 2a, 3a is part of the solder portion 4XA and is not a solder particle separated from the solder portion 4XA. In this embodiment, the amount of solder particles separated from the solder portion can be reduced, but solder particles separated from the solder portion may be present in the hardened portion.

[0143] If the amount of solder particles used is reduced, it becomes easier to obtain the connection structure 1. If the amount of solder particles used is increased, it becomes easier to obtain the connection structure 1X.

[0144] In the connection structure 1, 1X, when the opposing portion of the first electrode 2a and the second electrode 3a is viewed in the stacking direction of the first electrode 2a, the connection portion 4, 4X, and the second electrode 3a, the solder portions 4A, 4XA in the connection portion 4, 4X are preferably arranged in 50% or more of the 100% area of ​​the opposing portion of the first electrode 2a and the second electrode 3a. When the solder portions 4A, 4XA in the connection portion 4, 4X satisfy the above-mentioned preferred aspects, the electrical conductivity reliability can be further improved.

[0145] When the opposing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is preferably disposed over 50% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode. When the opposing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is more preferably disposed over 60% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode. When the opposing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is even more preferably disposed over 70% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode. It is particularly preferable that the solder portion in the connection portion be disposed over 80% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode when viewed in the stacking direction of the first electrode, the connection portion, and the second electrode. It is most preferable that the solder portion in the connection portion be disposed over 90% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode when viewed in the stacking direction of the first electrode, the connection portion, and the second electrode. When the solder portion in the connection portion satisfies the above-mentioned preferable aspects, the electrical connection reliability can be further improved.

[0146] When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is preferable that 60% or more of the solder portions in the connection portion are disposed in the opposing portions of the first electrode and the second electrode. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is more preferable that 70% or more of the solder portions in the connection portion are disposed in the opposing portions of the first electrode and the second electrode. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is even more preferable that 90% or more of the solder portions in the connection portion are disposed in the opposing portions of the first electrode and the second electrode. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is particularly preferable that 95% or more of the solder portion in the connection portion is disposed in the opposing portions of the first electrode and the second electrode. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is most preferable that 99% or more of the solder portion in the connection portion is disposed in the opposing portions of the first electrode and the second electrode. When the solder portion in the connection portion satisfies the above-mentioned preferable aspects, the electrical connection reliability can be further improved.

[0147] Next, with reference to FIG. 2, an example of a method for manufacturing the connection structure 1 using a conductive material according to one embodiment of the present invention will be described.

[0148] First, a first member to be connected 2 having a first electrode 2a on its surface (upper surface) is prepared. Next, as shown in FIG. 2(a), a conductive material 11 containing a thermosetting component 11B and solder particles 11A is placed on the surface of the first member to be connected 2 (first step). The conductive material 11 used contains a thermosetting compound and a thermosetting agent as the thermosetting component 11B. The conductive material 11 used contains an organic acid or a salt thereof and a compound having a hydroxyl group and a boiling point of 160°C or higher.

[0149] A conductive material 11 is placed on the surface on which the first electrode 2a of the first connection target component 2 is provided. After the conductive material 11 is placed, solder particles 11A are placed on both the first electrode 2a (lines) and the areas (spaces) where the first electrode 2a is not formed.

[0150] The method for disposing the conductive material 11 is not particularly limited, but examples thereof include application by a dispenser, screen printing, and ejection by an inkjet device.

[0151] Also, a second member to be connected 3 having a second electrode 3a on its surface (lower surface) is prepared. Next, as shown in FIG. 2(b), a second member to be connected 3 is placed on the surface of the conductive material 11 on the surface of the first member to be connected 2, opposite the first member to be connected 2 side of the conductive material 11 (second step). The second member to be connected 3 is placed on the surface of the conductive material 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

[0152] Next, the conductive material 11 is heated to a temperature equal to or higher than the melting point of the solder particles 11A (third step). Preferably, the conductive material 11 is heated to a temperature equal to or higher than the curing temperature of the thermosetting component 11B (thermosetting compound). During this heating, the solder particles 11A present in the area where no electrodes are formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). When a conductive paste is used instead of a conductive film, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. The solder particles 11A also melt and bond together. The thermosetting component 11B also thermally hardens. As a result, as shown in FIG. 2(c), a connection portion 4 connecting the first connection target member 2 and the second connection target member 3 is formed by the conductive material 11. The connection portion 4 is formed by the conductive material 11, and a solder portion 4A is formed by bonding multiple solder particles 11A together. The thermosetting component 11B thermally hardens to form a hardened portion 4B. If the solder particles 11A move sufficiently, it is not necessary to maintain a constant temperature from the time when the movement of the solder particles 11A that are not located between the first electrode 2a and the second electrode 3a begins until the movement of the solder particles 11A between the first electrode 2a and the second electrode 3a is completed.

[0153] In this embodiment, the conductive material 11 contains an organic acid or a salt thereof and a compound having a hydroxyl group and a boiling point of 160°C or higher, and thus exhibits flux activity at a relatively low temperature. When flux activity is exhibited at a relatively low temperature, the oxide film on the surface of the solder particles 11A contained in the conductive material 11 is removed at a relatively low temperature, and the solder particles 11A are connected to each other. By connecting the solder particles 11A to each other, the applied shape of the conductive material 11 can be maintained even when the conductive material 11 is heated by reflow or the like and the thermosetting component 11B melts. By maintaining the applied shape of the conductive material 11, the solder particles can be more efficiently arranged between the electrodes to be connected, and the electrical conductivity reliability and the electrical insulation reliability can be more effectively improved.

[0154] In this embodiment, it is preferable not to apply pressure in the second step and the third step. In this case, the weight of the second connection target member 3 is added to the conductive material 11. Therefore, when the connection portion 4 is formed, the solder particles 11A are more effectively gathered between the first electrode 2a and the second electrode 3a. Note that if pressure is applied in at least one of the second step and the third step, the action of the solder particles 11A to gather between the first electrode 2a and the second electrode 3a is more likely to be inhibited.

[0155] Furthermore, in this embodiment, because no pressure is applied, even if the first connection target member 2 and the second connection target member 3 are overlapped while the first electrode 2a and the second electrode 3a are misaligned, the misalignment can be corrected to connect the first electrode 2a and the second electrode 3a (self-alignment effect). This is because the molten solder that self-aggregates between the first electrode 2a and the second electrode 3a is energetically more stable when the contact area between the solder and other components of the conductive material between the first electrode 2a and the second electrode 3a is minimized, and a force acts to create an aligned connection structure with this minimum contact area. At this time, it is desirable that the conductive material is not hardened and that the viscosity of components of the conductive material other than the solder particles is sufficiently low at that temperature and time.

[0156] The viscosity (ηmp) of the conductive material at the melting point of the solder particles is preferably 50 Pa·s or less, more preferably 10 Pa·s or less, even more preferably 1 Pa·s or less, and preferably 0.1 Pa·s or more, more preferably 0.2 Pa·s or more. If the viscosity (ηmp) is equal to or less than the upper limit, the solder particles can be efficiently aggregated on the electrode. If the viscosity is equal to or greater than the lower limit, voids at the connection portion can be suppressed, and the conductive material can be prevented from spilling outside the connection portion.

[0157] The viscosity (ηmp) can be measured using a STRESSTECH (manufactured by REOLOGICA) or similar under the following conditions: strain control 1 rad, frequency 1 Hz, temperature rise rate 20°C / min, and measurement temperature range 25 to 200°C (however, if the melting point of the solder particles exceeds 200°C, the upper temperature limit is set to the melting point of the solder particles).From the measurement results, the viscosity at the melting point (°C) of the solder particles can be evaluated.

[0158] In this way, the connection structure 1 shown in FIG. 1 is obtained. The second step and the third step may be performed consecutively. After the second step, the obtained laminate of the first connection target member 2, the conductive material 11, and the second connection target member 3 may be moved to a heating unit, and the third step may be performed. To perform the heating, the laminate may be placed on a heating member, or the laminate may be placed in a heated space.

[0159] The heating temperature in the third step is preferably 140°C or higher, more preferably 160°C or higher, and preferably 450°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower.

[0160] Heating methods for the third step include heating the entire connection structure using a reflow furnace or oven to a temperature above the melting point of the solder particles and above the curing temperature of the thermosetting component, and locally heating only the connection portion of the connection structure.

[0161] Examples of tools used for localized heating include a hot plate, a heat gun that applies hot air, a soldering iron, and an infrared heater.

[0162] Furthermore, when heating locally with a hot plate, it is preferable to form the top surface of the hot plate with a metal having high thermal conductivity directly below the connection part, and with a material having low thermal conductivity such as fluororesin for other areas where heating is not desirable.

[0163] The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes, as well as electronic components such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flexible boards, glass epoxy boards, and glass boards. The first and second connection target members are preferably electronic components.

[0164] At least one of the first and second connection target members is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible substrate. The second connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible substrate. Resin films, flexible printed circuit boards, flexible flat cables, and rigid-flexible substrates are highly flexible and relatively lightweight. When a conductive film is used to connect such connection target members, solder particles tend not to collect on the electrodes. In contrast, by using a conductive paste, solder particles can be efficiently collected on the electrodes, even when a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible substrate is used, thereby sufficiently improving the conductivity reliability between electrodes. When a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible substrate is used, the effect of improving the conductivity reliability between electrodes by not applying pressure is more effectively achieved than when other connection target members such as semiconductor chips are used.

[0165] Examples of the electrode provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the connection target member is a flexible printed circuit board, the electrode is preferably a gold electrode, nickel electrode, tin electrode, silver electrode, or copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, copper electrode, molybdenum electrode, silver electrode, or tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode made of aluminum alone, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of materials for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

[0166] In the connection structure according to the present invention, the first electrode and the second electrode are preferably arranged in an area array or peripheral arrangement. When the first electrode and the second electrode are arranged in an area array or peripheral arrangement, the effects of the present invention are more effectively achieved. The area array refers to a structure in which the electrodes of the connection target component are arranged in a grid pattern on the surface on which the electrodes are arranged. The peripheral arrangement refers to a structure in which the electrodes are arranged on the outer periphery of the connection target component. In a structure in which the electrodes are arranged in a comb-like pattern, it is sufficient for the solder particles to aggregate in a direction perpendicular to the combs, whereas in the area array or peripheral structure, the solder particles must aggregate uniformly over the entire surface on which the electrodes are arranged. Therefore, while conventional methods tend to result in uneven solder amounts, the method of the present invention allows the solder particles to aggregate uniformly over the entire surface.

[0167] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0168] Thermosetting component (thermosetting compound): Thermosetting compound 1: "YSLV-80XY" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., tetramethylbisphenol F type epoxy resin Thermosetting compound 2: Nissan Chemical Industries "TEPIC-S", triisocyanurate epoxy resin Thermosetting compound 3: Nippon Steel & Sumikin Chemical's "YDF-8170C", bisphenol F type epoxy resin

[0169] Thermosetting component (thermosetting agent): Heat curing agent 1: Mitsubishi Chemical Corporation "YH306", trialkyltetrahydrophthalic anhydride

[0170] Thermosetting component (cure accelerator): Curing accelerator 1: Nippon Chemical Industry Co., Ltd. "PX-4MP", methyl tributyl phosphonium dimethyl phosphate

[0171] Organic acids or their salts: Organic acid or its salt 1: "Benzylamine adipate" manufactured by Showa Chemical Co., Ltd. Organic acid or its salt 2: "Di(2-ethylhexyl)phosphate" manufactured by TCI

[0172] Compound having a hydroxyl group and a boiling point of 160°C or higher (Compound A): Compound A1: Resorcinol, boiling point 280°C, hydroxyl group equivalent 55 g / mol, "Resorcinol" manufactured by Wako Pure Chemical Industries, Ltd. Compound A2: Stearic acid monoethanolamide, boiling point 485°C, hydroxyl group equivalent 327 g / mol, "Amizol SME" manufactured by Kawaken Fine Chemicals Co., Ltd. Compound A3: Butanol, boiling point 117°C, hydroxyl group equivalent 76 g / mol, "Butanol" manufactured by Wako Pure Chemical Industries, Ltd.

[0173] Solder particles: Solder particle 1: SnBi solder particle, melting point 138°C, solder particle selected from "Sn42Bi58" manufactured by Mitsui Kinzoku Co., Ltd., particle diameter: 10 μm Solder particle 2: SAC solder particle, melting point 220°C, solder particle selected from Mitsui Kinzoku's "Sn-Ag3-Cu0.5", particle diameter: 10 μm

[0174] Example 1 ,2,4,5,Reference example 3, and Comparative Examples 1 to 3) (1) Preparation of conductive material (anisotropic conductive paste) The components shown in Tables 1 and 2 below were mixed in the amounts shown in Tables 1 and 2 below to obtain a conductive material (anisotropic conductive paste).

[0175] (2) Fabrication of connection structure As the first connection target member, a glass epoxy board (material: FR-4, thickness: 0.6 mm) having copper electrodes (electrode length: 3 mm, electrode thickness: 12 μm) with L / S=50 μm / 50 μm on its surface was prepared.

[0176] As the second connection target member, a flexible printed circuit board (material: polyimide, thickness: 0.1 mm) having copper electrodes (electrode length: 3 mm, electrode thickness: 12 μm) with L / S=50 μm / 50 μm on its surface was prepared.

[0177] The conductive material (anisotropic conductive paste) immediately after preparation was applied to the upper surface of the glass epoxy substrate to a thickness of 100 μm to form a conductive material (anisotropic conductive paste) layer. Next, a flexible printed circuit board was laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes faced each other. The weight of the flexible printed circuit board was added to the conductive material (anisotropic conductive paste) layer. From this state, the conductive material (anisotropic conductive paste) layer was heated so that its temperature reached the melting point of the solder particles 5 seconds after the start of the temperature increase. Furthermore, 15 seconds after the start of the temperature increase, the conductive material (anisotropic conductive paste) layer was heated so that its temperature reached 200°C, and the conductive material (anisotropic conductive paste) layer was hardened, resulting in a connection structure. No pressure was applied during heating.

[0178] (evaluation) (1) The conductive material's coating shape retention properties A glass epoxy substrate (material: FR-4, thickness: 0.6 mm) with electrodes formed on its surface was prepared. The resulting conductive material was applied to the surface of the glass epoxy substrate using a dispenser ("SHOTmini100S" manufactured by Musashi Engineering Co., Ltd.) to a width of 300 μm, length of 2 cm, and thickness of 100 μm. A glass epoxy substrate with electrodes formed on the surface opposite the conductive material from the glass epoxy substrate was mounted using a flip-chip bonder ("FC-3000" manufactured by Toray Engineering Co., Ltd.) so that the electrodes faced each other. The width of the conductive material before heating was measured using an X-ray inspection device ("TUX-3210N" manufactured by Mars Tohken Solutions). The glass epoxy substrate with the conductive material applied was heated at 60°C, 80°C, or 100°C for 5 minutes. After heating, the glass epoxy substrate with the conductive material applied was removed and cooled at 25°C for 5 minutes, and the width of the conductive material after heating was measured. From the measurement results obtained, the ratio of the width of the conductive material after heating to the width of the conductive material before heating (width of the conductive material after heating / width of the conductive material before heating) was calculated. The coated shape retention property of the conductive material was evaluated according to the following criteria.

[0179] [Conductive material coating shape retention properties] ○: The ratio (width of conductive material after heating / width of conductive material before heating) is 1.2 or less △: The ratio (width of conductive material after heating / width of conductive material before heating) is greater than 1.2 and less than or equal to 1.5 ×: The ratio (width of conductive material after heating / width of conductive material before heating) exceeds 1.5

[0180] (2) Flux activity at low temperatures In the above (1) evaluation of the coated shape retention of the conductive material, a sample was prepared in which the conductive material was coated on a glass epoxy substrate. The sample was heated to 60°C, and the conductive material heated at 60°C was observed under a stereomicroscope to confirm whether the solder particles in the conductive material were connected to each other, and the presence or absence of flux activity at low temperatures was evaluated. The flux activity at low temperatures was evaluated according to the following criteria.

[0181] [Flux activity at low temperatures] ○: Solder particles are connected to each other, and the flux is active at low temperatures. ×: Solder particles are not connected to each other, and there is no flux activity at low temperatures

[0182] (3) Accuracy of solder placement on electrodes In the obtained connection structure, when the portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode, the proportion X of the area where the solder portion in the connection portion is arranged in 100% of the area where the first electrode and the second electrode face each other was evaluated. The placement accuracy of the solder on the electrode was evaluated according to the following criteria.

[0183] [Criteria for determining the accuracy of solder placement on electrodes] ○○○: Percentage X is 90% or more ○○: Percentage X is 80% or more but less than 90% ○: Proportion X is 70% or more but less than 80% ×: Percentage X is less than 70%

[0184] (4) Viscosity change of conductive material The viscosity (η25) of the anisotropic conductive paste at 25°C immediately after preparation was measured using an E-type viscometer ("TVE22L" manufactured by Toki Sangyo Co., Ltd.) at 25°C and 5 rpm. The anisotropic conductive paste immediately after preparation was left at 25°C for 8 hours, and then the viscosity (η25rt8) was measured using an E-type viscometer ("TVE22L" manufactured by Toki Sangyo Co., Ltd.) at 25°C and 5 rpm. The viscosity increase rate (η25rt8 / η25) was calculated from the measurement results. The viscosity change of the conductive material was judged according to the following criteria.

[0185] [Criteria for determining viscosity changes in conductive materials] ○: Viscosity increase rate (η25rt8 / η25) is less than 1.2 ×: Viscosity increase rate (η25rt8 / η25) is 1.2 or more

[0186] The results are shown in Table 1 below.

[0187] [Table 1]

[0188] Similar trends were observed when a flexible printed circuit board, a resin film, a flexible flat cable, and a rigid-flexible board were used. [Explanation of symbols]

[0189] 1,1X…Connection structure 2...First connection target member 2a...first electrode 3...Second connecting member 3a...Second electrode 4,4X…Connection part 4A, 4XA...Solder part 4B,4XB…Cured product part 11...Conductive materials 11A...Solder particles 11B...Thermosetting component

Claims

1. The solder paste comprises a thermosetting component, a plurality of solder particles, an organic acid or a salt thereof, and a compound having a hydroxyl group and a boiling point of 160°C or higher; the thermosetting component includes a thermosetting compound and a thermosetting agent; the compound having a hydroxyl group and a boiling point of 160°C or higher is a fatty acid alkylolamide or a polyhydric phenol compound; A conductive material, wherein the ratio of the content of the compound having a hydroxyl group and a boiling point of 160°C or higher in 100% by weight of the conductive material to the content of the organic acid or a salt thereof in 100% by weight of the conductive material is 0.5 or more and 2 or less.

2. 2. The conductive material according to claim 1, wherein the compound having a hydroxyl group and a boiling point of 160°C or higher has a hydroxyl group equivalent of 100 g / mol or higher.

3. 3. The conductive material according to claim 1, wherein the content of the compound having a hydroxyl group and a boiling point of 160°C or higher is 0.5% by weight or more and 2% by weight or less, based on 100% by weight of the conductive material.

4. The conductive material according to any one of claims 1 to 3, wherein the melting point of the solder particles is 180°C or lower.

5. The conductive material according to any one of claims 1 to 4, which is a conductive paste.

6. a first connection target member having a first electrode on a surface thereof; a second connection target member having a second electrode on its surface; a connection portion that connects the first connection target member and the second connection target member, The material of the connection portion is the conductive material according to any one of claims 1 to 5, A connection structure in which the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

7. 7. The connection structure according to claim 6, wherein, when the portion where the first electrode and the second electrode face each other is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is arranged in 50% or more of the 100% area of ​​the portion where the first electrode and the second electrode face each other.

8. A step of using the conductive material according to any one of claims 1 to 5 to place the conductive material on a surface of a first connection target member having a first electrode on a surface thereof; a step of placing a second connection target member having a second electrode on a surface of the conductive material opposite to the first connection target member side, such that the first electrode and the second electrode face each other; A method for manufacturing a connection structure, comprising the steps of: heating the conductive material to a temperature above the melting point of the solder particles to form a connection portion connecting the first connection target member and the second connection target member using the conductive material; and electrically connecting the first electrode and the second electrode using a solder portion in the connection portion.

9. 9. A method for manufacturing a connection structure as described in claim 8, which obtains a connection structure in which, when viewing the opposing portion of the first electrode and the second electrode in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is arranged over 50% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode.

Images