Electroconductive composition, electroconductive sheet, connection structure, method for manufacturing connection structure, laminate, and method for manufacturing laminate

Abstract

The present invention provides a novel electroconductive composition suitable for mounting a miniaturized electrode. The electroconductive composition of the present invention comprises an organic metal salt and a resin. An electroconductive sheet 1 of the present invention includes the electroconductive composition described above. A connection structure 100 of the present invention comprises: a first substrate 20 on which a first electrode 21 is arranged; a second substrate 30 on which a second electrode 31 is arranged; and a connection member 10 connecting the first substrate 20 and the second substrate 30. The connection member 10 is formed from the electroconductive composition described above. A laminate 200 of the present invention comprises a substrate 40 and a coating layer 15 covering the substrate 40. The coating layer 15 is formed from the electroconductive composition described above.

Description

Conductive composition, conductive sheet, connection structure, method for manufacturing connection structure, laminate, and method for manufacturing laminate

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

[0002] Anisotropic conductive compositions are used in technical fields such as substrate mounting for connecting electronic components to wiring boards. When heated while disposed between the electronic component and the wiring board, the anisotropic conductive composition exhibits conductivity in the stacking direction of the electronic component and the wiring board while ensuring insulation in the direction perpendicular to the stacking direction (plane direction).

[0003] Known anisotropic conductive compositions include those that combine solder particles and thermosetting resins (see, for example, Patent Document 1). When this anisotropic conductive composition is heated, the solder particles aggregate and melt between the electrodes of the electronic component and the electrodes of the wiring board. The molten solder then cools and solidifies, electrically connecting the electrodes of the electronic component and the electrodes of the wiring board. In areas where no electrodes are present, the aggregation of the solder particles does not progress, and the insulating properties of the resin are maintained. This mechanism results in anisotropy, whereby the electrical properties differ between the stacking direction and the surface direction of the electronic component and the wiring board.

[0004] JP 2012-216770 A

[0005] In recent years, as electrodes arranged on electronic components and wiring boards have become increasingly finer (especially at narrower pitches), solder particles in conventional conductive compositions tend to protrude beyond the area where the electrodes are located and aggregate, making it difficult to properly mount them. To accommodate the miniaturization of electrodes, it is possible to reduce the particle size of the solder particles. However, this not only requires a separate classification operation for the solder particles, but also tends to reduce the cohesiveness of the solder particles due to an increased proportion of oxide films on the solder particles.

[0006] Therefore, the present invention provides a new conductive composition suitable for mounting miniaturized electrodes.

[0007] The present invention provides a conductive composition comprising an organometallic salt and a resin.

[0008] The present invention further provides a conductive sheet comprising the above conductive composition.

[0009] The present invention further provides a connection structure comprising: a first substrate on which a first electrode is arranged; a second substrate on which a second electrode is arranged; and a connection member connecting the first substrate and the second substrate, wherein the connection member is formed from the above-mentioned conductive composition.

[0010] The present invention further provides a method for manufacturing the above-mentioned connection structure, comprising: placing the conductive composition between the first substrate and the second substrate; and heating the conductive composition to form the connection member.

[0011] The present invention further provides a laminate comprising: a substrate; and a coating layer that coats the substrate, wherein the coating layer is formed from the conductive composition described above.

[0012] The present invention further provides a method for producing the above-mentioned laminate, the method comprising: placing the conductive composition on the substrate; and heating the conductive composition to form the coating layer.

[0013] According to the present invention, a new conductive composition suitable for mounting miniaturized electrodes can be provided.

[0014] Fig. 2B is a cross-sectional view schematically showing a conductive sheet according to one embodiment of the present invention; Fig. 3C is a cross-sectional view schematically showing a connection structure according to one embodiment of the present invention; Fig. 4 is a view for explaining a method for manufacturing the connection structure of Fig. 2A; Fig. 5 is a cross-sectional view schematically showing a laminate according to one embodiment of the present invention; Fig. 6 is a view for explaining a method for manufacturing the laminate of Fig. 3A;

[0015] The conductive composition according to the first aspect of the present invention includes an organic metal salt and a resin.

[0016] In a second aspect of the present invention, for example, in the conductive composition according to the first aspect, the dissociation energy of the organometallic salt is 10,000 kJ / mol or less.

[0017] In a third aspect of the present invention, for example, in the conductive composition according to the first or second aspect, the organometallic salt contains an organic ion and a metal ion.

[0018] In a fourth aspect of the present invention, for example, in the conductive composition according to the third aspect, the organic ion has at least one selected from the group consisting of a carboxylate group and an enolate group.

[0019] In a fifth aspect of the present invention, for example, in the conductive composition according to the third or fourth aspect, the metal ions include at least one selected from the group consisting of gold ions, silver ions, copper ions, nickel ions, tin ions, and aluminum ions.

[0020] In a sixth aspect of the present invention, for example, in the conductive composition according to any one of the first to fifth aspects, the resin includes a thermosetting resin.

[0021] In a seventh aspect of the present invention, for example, in the conductive composition according to the sixth aspect, the thermosetting resin includes an epoxy resin.

[0022] In an eighth aspect of the present invention, for example, in the conductive composition according to the sixth or seventh aspect, the thermosetting resin includes a liquid epoxy resin and a solid epoxy resin.

[0023] In a ninth aspect of the present invention, for example, the conductive composition according to any one of the first to eighth aspects further contains an acid.

[0024] In a tenth aspect of the present invention, for example, in the conductive composition according to the ninth aspect, the acid includes an organic acid.

[0025] In an eleventh aspect of the present invention, for example, in the conductive composition according to the ninth or tenth aspect, the acid has an acid dissociation constant pKa of less than 5.3.

[0026] A conductive sheet according to a twelfth aspect of the present invention includes the conductive composition according to any one of the first to eleventh aspects.

[0027] A connection structure according to a thirteenth aspect of the present invention comprises: a first substrate on which a first electrode is arranged; a second substrate on which a second electrode is arranged; and a connection member that connects the first substrate and the second substrate, wherein the connection member is formed from a conductive composition according to any one of the first to eleventh aspects.

[0028] A method for manufacturing a connection structure according to a fourteenth aspect of the present invention is the same as the method for manufacturing a connection structure according to the thirteenth aspect, and includes: placing the conductive composition between the first substrate and the second substrate; and heating the conductive composition to form the connection member.

[0029] A laminate according to a fifteenth aspect of the present invention comprises: a substrate; and a coating layer that coats the substrate, wherein the coating layer is formed from the conductive composition according to any one of the first to eleventh aspects.

[0030] A method for manufacturing a laminate according to a sixteenth aspect of the present invention is the method for manufacturing a laminate according to the fifteenth aspect, comprising: placing the conductive composition on the substrate; and heating the conductive composition to form the coating layer.

[0031] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0032] <Embodiment of Conductive Composition> The conductive composition of this embodiment contains an organic metal salt and a resin. The conductive composition is typically an anisotropic conductive composition that can be used for substrate mounting, etc. In particular, the conductive composition is suitable for mounting miniaturized electrodes because it contains an organic metal salt.

[0033] In the conductive composition, the organometallic salt may be dispersed in the resin or may be compatible with the resin, but the organometallic salt may be partially aggregated in the resin, and the aggregated organometallic salt may have a particle shape.

[0034] (Organic Metallic Salt) The organic metal salt is typically a salt containing an organic ion and a metal ion. The organic metal salt preferably has a dissociation energy of 10,000 kJ / mol or less. An organic metal salt with a low dissociation energy allows the heating temperature of the conductive composition during mounting to be set low. The dissociation energy of the organic metal salt is preferably 8,000 kJ / mol or less, and may be 5,000 kJ / mol or less, 3,500 kJ / mol or less, 3,000 kJ / mol or less, 1,000 kJ / mol or less, 800 kJ / mol or less, or even 700 kJ / mol or less. The lower limit of the dissociation energy of the organic metal salt may be, for example, 100 kJ / mol or more, 300 kJ / mol or more, or even 500 kJ / mol or more. In particular, organometallic salts with dissociation energies of 300 to 800 kJ / mol can be ionized at low temperatures, and the formed metal ions have high mobility within the resin, making them suitable for low-temperature mounting.

[0035] In this specification, the dissociation energy of an organometallic salt refers to the energy required to dissociate each ion (typically an organic ion and a metal ion) contained in the organometallic salt. The dissociation energy of an organometallic salt can be, for example, the energy E M and the energy of the organic ion alone E O From the sum of these values, the energy E of the organic metal salt S The value obtained by subtracting M +E O -E S ) corresponds to the energy E M , E O and E S The value can be calculated by quantum chemical calculation.

[0036] The organic ion contained in the organometallic salt is typically an anion and has a functional group X containing a negative charge. The functional group X is a carboxylate group (-COO - ), enolate group (-CR=C(-O -) R: R are each independently a hydrogen atom or an arbitrary substituent. The organic ion preferably has, as the functional group X, at least one selected from the group consisting of a carboxylate group and an enolate group, and particularly preferably has a carboxylate group.

[0037] The number of functional groups X contained in the organic ion is not particularly limited and may be, for example, 1 to 5, or may be 1 to 3. The organic ion preferably contains one functional group X.

[0038] The organic ion is preferably one in which at least one hydrogen atom contained in a hydrocarbon compound has been substituted with a functional group X. The hydrocarbon compound may further have a substituent other than the functional group X. Examples of the other substituent include a halogen group, a hydroxyl group, and a ketone group. Examples of the halogen include fluorine, chlorine, bromine, and iodine.

[0039] The number of carbon atoms in the hydrocarbon compound is, for example, 1 to 10, and may be 1 to 5, or even 1 to 3. The hydrocarbon compound may be linear or branched. The hydrocarbon compound is preferably an alkane. Examples of alkanes include methane, ethane, and propane. The hydrocarbon compound may contain a ring structure such as an aromatic ring, or may not contain a ring structure. A specific example of an aromatic ring is a benzene ring.

[0040] Specific examples of organic ions containing a carboxylate group as the functional group X include lactate ion, acetate ion, trifluoroacetate ion, formate ion, citrate ion, benzoate ion, etc. Specific examples of organic ions containing an enolate group as the functional group X include acetylacetonate, etc.

[0041] The metal ion contained in the organic metal salt is typically a cation. The valence of the metal ion is, for example, 1 to 4, and may be 1 or 2.

[0042] The metal ions can be selected appropriately depending on, for example, the use of the connection structure described below, the type of substrate, the conditions for producing the connection structure, etc., and preferably include at least one selected from the group consisting of gold ions, silver ions, copper ions, nickel ions, tin ions, and aluminum ions.

[0043] Specific examples of organic metal salts include silver lactate, silver benzoate, silver trifluoroacetate, silver tricitrate hydrate, silver acetylacetonate, copper(II) acetylacetonate, and tin(II) acetate.

[0044] The content of the organometallic salt in the conductive composition may be, for example, 0.1 wt % or more, 0.5 wt % or more, 1.0 wt % or more, 3.0 wt % or more, 5.0 wt % or more, 8.0 wt % or more, or even 10 wt % or more. The upper limit of the content of the organometallic salt may be, for example, 60 wt % or less, 40 wt % or less, or even 20 wt % or less.

[0045] (Resin) Resins known in the field of anisotropic conductive compositions can be used, including, for example, thermosetting resins and thermoplastic resins. The resin preferably includes a thermosetting resin. The thermosetting resin preferably includes an epoxy resin, and particularly preferably includes both a liquid epoxy resin and a solid epoxy resin. However, the thermosetting resin may include only a liquid epoxy resin as the epoxy resin. In this specification, "liquid" means a substance that is in a liquid state at atmospheric pressure (101.325 kPa) and 20°C, and "solid" means a substance that is in a solid state at atmospheric pressure and 20°C. The resin may be a water-soluble resin that can be dissolved in water.

[0046] Examples of epoxy resins (thermosetting epoxy resins) include bisphenol-type epoxy resins (e.g., bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins), novolac-type epoxy resins (e.g., phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, and biphenyl-type epoxy resins), naphthalene-type epoxy resins, fluorene-type epoxy resins (e.g., bisarylfluorene-type epoxy resins), and triphenylmethane-type epoxy resins (e.g., trishydroxyphenylmethane-type epoxy resins).

[0047] The resin contained in the conductive composition is not limited to epoxy resin. Examples of resins other than epoxy resin include acrylic resin, polyester resin, amino resin, urea resin, urethane resin, butyral resin, polyvinyl alcohol resin, phenol resin, polyamide resin, and melamine resin.

[0048] The conductive composition preferably contains both a liquid resin (liquid resin) and a solid resin (solid resin). The ratio of the solid resin content (wt%) to the total value of the liquid resin content (wt%) and the solid resin content (wt%) in the conductive composition is, for example, 50% or more, and may be 60% or more, 70% or more, 80% or more, or even 90% or more. This ratio may even be 100%. The higher this ratio, the less likely the material in the conductive sheet to repel the release sheet over time when the conductive composition is applied to a release sheet to produce a conductive sheet.

[0049] The resin content in the conductive composition is, for example, 30 wt % or more, and may be 50 wt % or more, 70 wt % or more, or even 80 wt % or more. The upper limit of the resin content is, for example, 99 wt % or less, and may be 95 wt % or less.

[0050] (Acid) The conductive composition preferably further contains an acid, which allows the heating temperature of the conductive composition during mounting to be set even lower.

[0051] The acid preferably has an acid dissociation constant pKa (particularly, the first acid dissociation constant) of less than 5.3. The pKa of the acid is preferably 5.0 or less, and may be 4.7 or less, 4.5 or less, 4.0 or less, 3.5 or less, 3.0 or less, or even 2.5 or less. The lower the pKa of the acid, the more easily the organometallic salt can be ionized at a low temperature, making it suitable for low-temperature mounting. The lower limit of the pKa of the acid is, for example, 1.5 or more. In this specification, pKa is the value in water at 25°C.

[0052] Examples of the acid include organic acids and inorganic acids. The acid preferably includes an organic acid. The organic acid is typically a compound containing an acidic group such as a carboxyl group. The number of acidic groups contained in the organic acid is, for example, 1 or more, and may be 1 to 3, or even 1 to 2. The organic acid preferably includes one acidic group.

[0053] The organic acid is preferably a hydrocarbon compound in which at least one hydrogen atom is substituted with an acidic group. The hydrocarbon compound may further have a substituent other than the acidic group. Examples of the hydrocarbon compound and other substituents include those described above for the organometallic salt.

[0054] The hydrocarbon compound is preferably an alkane or an alkene. Examples of the alkane include those described above for the organometallic salt. Examples of the alkene include ethylene and propylene.

[0055] Specific examples of the organic acid include acrylic acid, trifluoromethylacrylic acid, methacrylic acid, lactic acid, glutaric acid, and formic acid.

[0056] Specific examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid.

[0057] The content of the acid in the conductive composition is, for example, 10 wt % to 60 wt %, and may be 30 wt % to 50 wt %. The conductive composition may not contain an acid.

[0058] (Other Components) The conductive composition may further contain other components in addition to the organometallic salt, resin, and acid, such as a solvent, a curing agent, a thixotropic agent, an antifoaming agent, an antioxidant, a thickener, a complexing agent, a reducing agent, and a pH buffer.

[0059] The content of other components in the conductive composition is, for example, 30 wt % or less, and may be 10 wt % or less, 5 wt % or less, 1 wt % or less, or even 0.1 wt % or less. The conductive composition may be substantially free of other components (particularly solvents).

[0060] <Embodiment of Conductive Sheet> FIG. 1 is a cross-sectional view schematically showing a conductive sheet 1 of this embodiment. The conductive sheet 1 contains the conductive composition described above. Specifically, the conductive sheet 1 has the same composition as the conductive composition except that it does not contain a solvent. However, the conductive sheet 1 may contain a small amount of solvent derived from the conductive composition. Note that when the conductive composition contains a thermosetting resin, the thermosetting resin is typically present in an uncured state in the conductive sheet 1.

[0061] The thickness of the conductive sheet 1 is, for example, 0.1 μm or more, and may be 1 μm or more, 5 μm or more, or even 10 μm or more. The upper limit of the thickness of the conductive sheet 1 is, for example, 10 mm or less, and may be 1 mm or less, 500 μm or less, 100 μm or less, or even 50 μm or less. The thickness of the conductive sheet 1 is preferably 5 μm to 50 μm.

[0062] The conductive sheet 1 can be produced, for example, by the following method. First, a release sheet is prepared, and a conductive composition is applied onto the release sheet. The resulting coating film is dried to form the conductive sheet 1 on the release sheet. The release sheet is peeled off from the conductive sheet 1, thereby obtaining the conductive sheet 1.

[0063] <Embodiment of Connection Structure> Fig. 2A is a cross-sectional view schematically showing a connection structure 100 according to this embodiment. The connection structure 100 includes a first substrate 20, a second substrate 30, and a connection member 10. A first electrode 21 is disposed on the first substrate 20, and a second electrode 31 is disposed on the second substrate 30. The connection member 10 is formed from the conductive composition described above, and connects the first substrate 20 and the second substrate 30. The first substrate 20, the connection member 10, and the second substrate 30 are arranged in this order in the stacking direction Y.

[0064] The first substrate 20 has a main surface (the surface of the first substrate 20 having the largest area) facing the connection member 10, and first electrodes 21 are arranged on this main surface. The first electrodes 21 may be arranged in a pattern on the first substrate 20. Furthermore, a plurality of first electrodes 21 may be arranged on the first substrate 20. In the example of FIG. 2A , a plurality of first electrodes 21a, 21b, and 21c are arranged on the first substrate 20. The width (line) of the first electrodes 21 may be 20 μm or less, or 10 μm or less. The distance (space) between two adjacent first electrodes 21 may be 20 μm or less, or 10 μm or less. The combination of lines and spaces (L / S: line and space) of the first electrodes 21 may be 20 μm or less / 20 μm or less, or 10 μm or less / 10 μm or less.

[0065] Like the first substrate 20, the second substrate 30 has a main surface facing the connection member 10, and a second electrode 31 is disposed on the main surface. The second electrode 31 faces the first electrode 21, and these electrodes 21 and 31 are aligned along the stacking direction Y. Specifically, the second electrode 31 overlaps the first electrode 21 in a plan view. The second electrode 31 may be disposed in a pattern on the second substrate 30. Furthermore, a plurality of second electrodes 31 may be disposed on the second substrate 30. In the example of FIG. 2A , a plurality of second electrodes 31a, 31b, and 31c are disposed on the second substrate 30. The plurality of second electrodes 31a, 31b, and 31c face a plurality of first electrodes 21a, 21b, and 21c, respectively. The L / S of the second electrode 31 is typically the same as that of the first electrode 21.

[0066] Known materials can be used as the materials for the first electrode 21 and the second electrode 31. The materials for the first electrode 21 and the second electrode 31 are, for example, metals such as copper and nickel.

[0067] Specific examples of the first substrate 20 and the second substrate 30 on which electrodes are arranged include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes; and wiring substrates such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flexible boards, glass epoxy boards, and glass boards. It is preferable that one of the first substrate 20 and the second substrate 30 is an electronic component and the other is a wiring board.

[0068] The connecting member 10 has a conductive portion 6 and an insulating portion 7. The conductive portion 6 is in direct contact with each of the first electrode 21 arranged on the first substrate 20 and the second electrode 31 arranged on the second substrate 30, electrically connecting them. The conductive portion 6 can exhibit conductivity in the stacking direction Y.

[0069] The conductive portion 6 preferably overlaps each of the first electrode 21 and the second electrode 31 in a plan view. When the first electrode 21 and the second electrode 31 are arranged in a pattern, the conductive portion 6 is also preferably arranged in a pattern. The connection member 10 may have a plurality of conductive portions 6. In the example of FIG. 2A , the connection member 10 has a plurality of conductive portions 6a, 6b, and 6c. The conductive portion 6a is in direct contact with each of the first electrode 21a and the second electrode 31a, the conductive portion 6b is in direct contact with each of the first electrode 21b and the second electrode 31b, and the conductive portion 6c is in direct contact with each of the first electrode 21c and the second electrode 31c.

[0070] The conductive portion 6 preferably contains a metal as a main component. The metal contained in the conductive portion 6 is typically derived from an organometallic salt of the conductive composition. In this specification, the term "main component" refers to the component that is contained in the largest amount by weight in the referenced member. The conductive portion 6 may contain components other than metal (e.g., resin).

[0071] The insulating portion 7 surrounds the conductive portion 6 and fills the space between the first substrate 20 and the second substrate 30 where the conductive portion 6 is not present. The insulating portion 7 is in direct contact with both the surface of the first substrate 20 on which the first electrode 21 is not arranged and the surface of the second substrate 30 on which the second electrode 31 is not arranged. The insulating portion 7 ensures insulation in the planar direction X orthogonal to the stacking direction Y.

[0072] The insulating part 7 preferably contains a resin as a main component. The resin contained in the insulating part 7 may be the same as the resin of the conductive composition, or may be a cured product of the resin of the conductive composition (particularly a thermosetting resin). Note that the insulating part 7 may contain components other than the resin (for example, an organic metal salt).

[0073] The manufacturing method of the connection structure 100 of this embodiment includes, for example, placing a conductive composition between the first substrate 20 and the second substrate 30, and heating the conductive composition to form the connection member 10.

[0074] Specifically, the connection structure 100 can be produced by the following method: First, as shown in Fig. 2B, a conductive sheet 1 containing a conductive composition is placed between the first substrate 20 and the second substrate 30. However, the conductive composition may also be placed between the first substrate 20 and the second substrate 30 using a known coating method or printing method without using the conductive sheet 1.

[0075] Next, the conductive sheet 1 containing the conductive composition is heated. The conductive sheet 1 can be heated using a reflow furnace or an oven. The heating temperature of the conductive sheet 1 can be adjusted appropriately depending on the composition of the conductive composition, and is, for example, 30°C to 300°C. The heating temperature of the conductive sheet 1 may be 250°C or less, 200°C or less, 180°C or less, 150°C or less, 130°C or less, 100°C or less, 80°C or less, or even 50°C or less. The heating time of the conductive sheet 1 is not particularly limited, and is, for example, 1 second to 10 minutes.

[0076] When the conductive sheet 1 is heated, metal derived from the organometallic salt in the conductive composition is deposited on the surfaces of the first electrode 21 and the second electrode 31, and the deposits form the conductive portion 6. The deposition of metal on the electrodes can occur when metal ions contained in the organometallic salt undergo an oxidation-reduction reaction with the electrode material, etc. On the surface of the first substrate 20 where the first electrode 21 is not disposed or on the surface of the second substrate 30 where the second electrode 31 is not disposed, no metal deposition occurs, and an insulating portion 7 is formed. Note that when the conductive sheet 1 is heated, the conductive sheet 1 may soften, and the first electrode 21 and the second electrode 31 may each sink into the conductive sheet 1. If the conductive composition contains a thermosetting resin, it is preferable that the thermosetting resin be cured by heating the conductive sheet 1.

[0077] When the conductive sheet 1 is heated, stress may be applied in the stacking direction Y to the laminate of the first substrate 20, the conductive sheet 1, and the second substrate 30 to compress and bond them together. This operation tends to improve the strength of the connection structure 100.

[0078] As described above, by heating the conductive sheet 1, a connection member 10 having a conductive portion 6 and an insulating portion 7 is formed, thereby obtaining a connection structure 100. The conductive composition of this embodiment contains an organometallic salt instead of conventional solder particles. The metal ions contained in the organometallic salt are not only significantly smaller in size than the solder particles, but can also deposit metal on an electrode using an oxidation-reduction reaction. Therefore, the conductive composition of this embodiment can reliably form the conductive portion 6 on the electrode, even when a miniaturized electrode (e.g., an electrode with an L / S ratio of 20 μm or less / 20 μm or less) is used, making it suitable for mounting.

[0079] 3A is a cross-sectional view schematically illustrating a laminate 200 according to this embodiment. The laminate 200 includes a substrate 40 and a coating layer 15. The coating layer 15 is formed from the conductive composition described above and coats the substrate 40. Specifically, the coating layer 15 coats one of the main surfaces of the substrate 40. The coating layer 15 may coat the entire main surface of the substrate 40, or may coat only a portion of the main surface of the substrate 40.

[0080] An electrode 41 is disposed on the substrate 40. The electrode 41 is disposed, for example, on the main surface of the substrate 40 facing the coating layer 15. The electrode 41 may be disposed in a pattern on the substrate 40. Alternatively, a plurality of electrodes 41 may be disposed on the substrate 40. In the example of FIG. 3A , a plurality of electrodes 41 a, 41 b, and 41 c are disposed on the substrate 40. Examples of the substrate 40 and the electrode 41 include those described above for the first substrate 20 and the first electrode 21.

[0081] The covering layer 15 has, for example, a conductive portion 16 and an insulating portion 17. The conductive portion 16 of the covering layer 15 is in direct contact with an electrode 41 arranged on the substrate 40 and is electrically connected to the electrode 41. The conductive portion 16 extends in the stacking direction Y of the substrate 40 and the covering layer 15.

[0082] The conductive portions 16 preferably overlap the electrodes 41 in a plan view. When the electrodes 41 are arranged in a pattern, the conductive portions 16 are also preferably arranged in a pattern. The covering layer 15 may have a plurality of conductive portions 16. In the example of FIG. 3A , the covering layer 15 has a plurality of conductive portions 16a, 16b, and 16c. The conductive portion 16a is in direct contact with the electrode 41a, the conductive portion 16b is in direct contact with the electrode 41b, and the conductive portion 16c is in direct contact with the electrode 41c. The material of the conductive portions 16 is the same as that described above for the connecting member 10.

[0083] The insulating portion 17 surrounds the conductive portion 16 and is in direct contact with the surface of the substrate 40 on which the electrodes 41 are not disposed. The material of the insulating portion 17 is the same as that described above for the connecting member 10.

[0084] The method for manufacturing the laminate 200 of this embodiment includes, for example, disposing a conductive composition on the substrate 40 and heating the conductive composition to form the coating layer 15 .

[0085] Specifically, the laminate 200 can be produced by the following method: First, as shown in Fig. 3B, a conductive sheet 1 containing a conductive composition is placed on a substrate 40. However, the conductive composition may be placed on the substrate 40 using a known coating method or printing method without using the conductive sheet 1.

[0086] Next, the conductive sheet 1 containing the conductive composition is heated. The heating conditions for the conductive sheet 1 include those described above for the connection structure 100. When the conductive sheet 1 is heated, metal derived from the organometallic salt in the conductive composition deposits on the surface of the electrode 41, and the deposit forms the conductive portion 16. Metal deposition on the electrode can occur when metal ions contained in the organometallic salt undergo an oxidation-reduction reaction with the electrode material, etc. On the surface of the substrate 40 where the electrode 41 is not disposed, no metal deposition occurs, and an insulating portion 17 is formed. Note that when the conductive sheet 1 is heated, the conductive sheet 1 may soften, causing the electrode 41 to sink into the conductive sheet 1. If the conductive composition contains a thermosetting resin, it is preferable that the thermosetting resin harden when the conductive sheet 1 is heated.

[0087] When the conductive sheet 1 is heated, stress may be applied to the laminate of the substrate 40 and the conductive sheet 1 in the lamination direction Y to compress them together. This operation tends to improve the strength of the laminate 200.

[0088] As described above, by heating the conductive sheet 1, the covering layer 15 having the conductive portion 16 and the insulating portion 17 is formed, and thus the laminate 200 can be obtained.

[0089] When the conductive composition contains a thermoplastic resin or a water-soluble resin, the insulating portion 17 can be removed with a solvent such as water or an organic solvent. In this case, the coating layer 15 does not need to have the insulating portion 17, and may be composed of only the conductive portion 16.

[0090] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0091] Example 1 First, 50 parts by weight of liquid epoxy resin (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, jER828) was added to 10 parts by weight of silver trifluoroacetate salt as an organic metal salt, and the mixture was stirred until homogeneous. To the resulting mixture, 50 parts by weight of solid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-017) and acetone were added. This resulted in a conductive composition with a solids concentration of 70 wt%. Next, this conductive composition was applied to a release liner using an applicator and dried at 60°C for 5 minutes. This resulted in the conductive sheet (thickness 10 μm) of Example 1.

[0092] (Examples 2 to 33) Conductive sheets of Examples 2 to 33 were obtained by the same method as Example 1, except that the types and amounts of organometallic salts and resins were changed as shown in Tables 1 to 3. In Examples 8 to 33, an acid was also added to the mixed solution along with the solid epoxy resin and acetone.

[0093] Comparative Example 1: First, 50 parts by weight of liquid epoxy resin (bisphenol A-type epoxy resin, jER828, manufactured by Mitsubishi Chemical Corporation) was added to 175 parts by weight of solder particles (SAC305, Sn96.5Ag3.0Cu0.5, manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size (D50) 7 μm) and stirred until homogeneous. The resulting mixture was then mixed with 50 parts by weight of solid epoxy resin (YD-017, manufactured by Nippon Steel Chemical & Material Co., Ltd.), 15 parts by weight of glutaric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and acetone. This resulted in a conductive composition with a solids concentration of 70 wt%. Next, this conductive composition was applied to a release liner using an applicator and dried at 60°C for 5 minutes. This resulted in a conductive sheet (thickness 10 μm) of Comparative Example 1.

[0094] Comparative Example 2 A conductive sheet (thickness 10 μm) of Comparative Example 2 was obtained by the same method as Comparative Example 1, except that SAC305 (Sn96.5Ag3.0Cu0.5, manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size (D50) 10 μm) was used as the solder particles.

[0095] [Evaluation] (Dissociation energy of organometallic salt) The dissociation energy of the organometallic salt used in the examples was measured by the following method. First, a three-dimensional structure was generated from the molecular structure of the organometallic salt in smiles notation using the RDkit module of Python. At this time, silver ions (Ag + ) to rubidium ions (Rb + ) and tin ions (Sn 2+ ) to copper ions (Cu 2+ The resulting three-dimensional structure of the molecule was 4 × 4 × 3 nm 3 The structure was placed under a periodic boundary condition of . Using this structure as the initial structure, molecular dynamics calculations of the NVE ensemble were performed under conditions of 800 K and 1 ns. From the trajectory of the calculation results, structures were extracted every 5 ps, and structural optimization calculations were performed on all of them. Of the 200 optimized structures obtained, the structure with the lowest energy (stable structure) was extracted. The molecular dynamics calculations and structural optimization calculations were performed using the Forcite module of Materials Studio manufactured by Dassault Systèmes. The COMPASS III force field was used in the molecular dynamics calculations.

[0096] Next, for the obtained stable structure, the replaced metal ion was replaced again with the original metal ion. Using the structure after substitution as the initial structure, a structural optimization calculation was performed. Energy evaluation was performed by single-point calculation for the obtained optimized structure and the organic ion and metal ion extracted from this optimized structure, and each energy was determined. Energy E of the metal ion M and the energy of the organic ion alone E O From the sum of these values, the energy E of the organic metal salt S The value obtained by subtracting M +E O -E S ) was identified as the dissociation energy of the organometallic salt. Quantum chemical calculations were performed using Gaussian 16 manufactured by Gaussian Corporation. B3LYP / LANL2DZ was used for the function system and basis set, and the D3 correction by Grimme et al. was applied.

[0097] (Mounting Evaluation) For the conductive sheets of the Examples and Comparative Examples, mounting evaluation of miniaturized electrodes was performed by the following method. First, a dummy wafer (substrate) on which 700 electrodes were arranged was prepared. The substrate had a size of 10 mm length x 10 mm width. The electrodes were cylindrical with a diameter of 10 μm, and the distance between adjacent electrodes was 10 μm (L / S: 10 μm / 10 μm).

[0098] Next, a conductive sheet measuring 10 mm long x 10 mm wide was placed on the substrate so as to contact the electrodes, and a bonding process was performed at 50°C under vacuum conditions. Next, a non-alkali glass sheet measuring 10 mm long x 10 mm wide was placed on the conductive sheet, and further bonding was performed. The resulting test piece was placed in a vacuum pressure reflow machine (Model 1200 Table Top Furnace, manufactured by SST International) and a vacuum atmosphere was created.

[0099] Next, the test specimen was heated at a temperature increase rate of 100°C / min so that the maximum temperature was the temperature listed in Tables 1 to 4. At this time, the test specimen was pressurized with nitrogen to 4.5 atmospheres. The test specimen was heated at the maximum temperature for 2 minutes. A coating layer covering the substrate was formed by the heat treatment. The surface of this coating layer was observed from the alkali-free glass side with an optical microscope (Keyence Corporation, VHX-8000). In detail, microscopic observation was performed at seven locations at a magnification of 500 times. The observation positions selected were, based on one corner of the conductive sheet, position P1 (2.5 mm x 2.5 mm), position P2 (2.5 mm x 7.5 mm), position P3 (5.0 mm x 2.5 mm), position P4 (5.0 mm x 5.0 mm), position P5 (5.0 mm x 7.5 mm), position P6 (7.5 mm x 2.5 mm), and position P7 (7.5 mm x 7.5 mm).

[0100] At each observation position, it was confirmed whether or not a conductive part had been formed (whether or not it had been integrated) for each electrode. Those in which a conductive part had been formed were rated as good (◯), and the ratio of the number of electrodes rated as good to the total number of electrodes observed was calculated, and mounting evaluation was performed based on the following criteria. Evaluation criteria 1: The above ratio is 30% or less. 2: The above ratio is more than 30% and 60% or less. 3: The above ratio is more than 60% and 90% or less. 4: The above ratio is more than 90% and 100% or less.

[0101] For the mounting evaluation, a dummy wafer with copper electrodes and a dummy wafer with nickel electrodes were used.

[0102] (Continuity Test) Using the conductive sheets of the Examples and Comparative Examples, connection structures were produced by the following method, and the conductivity was evaluated.

[0103] (1) Fabrication of Connection Structure First, two FPC boards with Cu electrodes (electrodes 100 μm square, distance between electrode edges 100 μm) were prepared. Next, the release liner was peeled off from the prepared conductive sheet, and the conductive sheet was placed between the two FPC boards. At this time, a high-precision die bonding device (manufactured by Finetech, product name "FINEPLACER Lambda 2") was used to adjust the electrodes of the opposing FPC boards so that they were aligned via the conductive sheet.

[0104] Next, the laminate was placed in a vacuum pressure reflow furnace (manufactured by SST Vacuum Reflow Systems, Inc., product name "Model 1200 Table Top Furnace") and evacuated. Next, under conditions of 4.5 atmospheres of nitrogen gas, the temperature was increased at a rate of 100°C / min to the temperatures listed in Tables 1 to 3, and the temperature was maintained for 15 minutes to obtain a connection structure.

[0105] (2) Evaluation of Conductivity The electrical resistance between the opposing electrodes of this connection structure was measured using a digital multimeter (name "PC500a", manufactured by Sanwa Electric Measurement Co., Ltd.), and the electrical connection (conductivity) of the opposing electrodes was evaluated based on the following criteria: 2: The electrical resistance could be measured (the electrical resistance was measured as a positive value). 1: The electrical resistance could not be measured (the measurement range of the multimeter was overloaded).

[0106]

[0107]

[0108]

[0109]

[0110] The abbreviations in Tables 1 to 4 are as follows: jER828: Liquid epoxy resin (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, jER828) YD-017: Solid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-017)

[0111] The organometallic salts and acids used in the examples were all manufactured by Sigma Aldrich.

[0112] As can be seen from Tables 1 to 4, the conductive compositions of the examples containing an organometallic salt and a resin had better results in the mounting evaluation than the conductive compositions of the comparative examples. From these results, it can be said that the conductive compositions of the examples are suitable for mounting miniaturized electrodes.

[0113] The conductive composition of this embodiment can be used for mounting miniaturized electrodes.

Claims

1. A conductive composition comprising an organic metal salt and a resin.

2. The conductive composition according to claim 1, wherein the dissociation energy of the organometallic salt is 10,000 kJ / mol or less.

3. The conductive composition of claim 1, wherein the organometallic salt comprises an organic ion and a metal ion.

4. The conductive composition according to claim 3, wherein the organic ion has at least one selected from the group consisting of a carboxylate group and an enolate group.

5. The conductive composition according to claim 3, wherein the metal ions include at least one selected from the group consisting of gold ions, silver ions, copper ions, nickel ions, tin ions, and aluminum ions.

6. The conductive composition of claim 1, wherein the resin comprises a thermosetting resin.

7. The conductive composition according to claim 6, wherein the thermosetting resin comprises an epoxy resin.

8. The conductive composition according to claim 6, wherein the thermosetting resin includes a liquid epoxy resin and a solid epoxy resin.

9. The conductive composition of claim 1, further comprising an acid.

10. The conductive composition of claim 9, wherein the acid comprises an organic acid.

11. The conductive composition according to claim 9, wherein the acid has an acid dissociation constant pKa of less than 5.

3.

12. A conductive sheet comprising the conductive composition according to any one of claims 1 to 11.

13. A connection structure comprising: a first substrate on which a first electrode is arranged; a second substrate on which a second electrode is arranged; and a connection member that connects the first substrate and the second substrate, wherein the connection member is formed from the conductive composition according to any one of claims 1 to 11.

14. A method for manufacturing a connection structure according to claim 13, comprising: disposing the conductive composition between the first substrate and the second substrate; and heating the conductive composition to form the connection member.

15. A laminate comprising: a substrate; and a coating layer that coats the substrate, wherein the coating layer is formed from the conductive composition according to any one of claims 1 to 11.

16. A method for producing a laminate according to claim 15, comprising: disposing the conductive composition on the substrate; and heating the conductive composition to form the coating layer.

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