TW202603100A - Conductive composites, conductive sheets, connecting structures, manufacturing methods of connecting structures, laminates, and manufacturing methods of laminates. - Google Patents

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 composites, conductive sheets, connecting structures, manufacturing methods of connecting structures, laminates, and manufacturing methods of laminates.

This invention relates to a conductive composite, a conductive sheet, a connecting structure, a method for manufacturing a connecting structure, a laminate, and a method for manufacturing a laminate.

In the field of substrate mounting technology, which connects electronic components to wiring boards, anisotropic conductive composites are utilized. Anisotropic conductive composites exhibit conductivity in the stacking direction of the electronic components and wiring boards when heated while disposed between the electronic components and the wiring board, while ensuring insulation in the direction orthogonal to the stacking direction (planar direction).

Anisotropic conductive compositions are known to be formed by combining solder particles and thermosetting resins (e.g., Patent 1). When this anisotropic conductive composition is heated, the solder particles condense and melt between the electrodes of the electronic component and the electrodes of the wiring substrate. Subsequently, the molten solder is cooled and solidified, thereby electrically connecting the electrodes of the electronic component and the wiring substrate. In areas where electrodes are not present, the insulation provided by the resin is maintained, and the solder particles do not condense. Through this mechanism, anisotropy is exhibited in the electrical properties, differing between the lamination direction and the planar direction of the electronic component and the wiring substrate. [Prior Art Documents] [Patent Documents]

Patent Document 1: Japanese Patent Application Publication No. 2012-216770

[Problem to be Solved by the Invention] In recent years, with the miniaturization (especially narrowing of the spacing) of electrodes disposed on electronic components or wiring boards, solder particles tend to overflow and aggregate in the electrode area in previous conductive compositions, making them difficult to install properly. To address the miniaturization of electrodes, the particle size of solder particles has also been considered. However, in this case, not only is it necessary to perform additional sorting of solder particles, but the ratio of oxide coating in the solder particles also increases, which tends to reduce the cohesiveness of solder particles.

To address this, the present invention provides a novel conductive assembly suitable for the installation of miniaturized electrodes. [Technical means to solve the problem]

This invention provides: a conductive composition comprising an organometallic salt and a resin.

Furthermore, the present invention provides: a conductive sheet comprising the above-mentioned conductive composition.

Furthermore, the present invention provides: a connection structure comprising: a first substrate having a first electrode disposed thereon; a second substrate having a second electrode disposed thereon; and a connection member connecting the first substrate and the second substrate; wherein the connection member is formed of the conductive composite.

Furthermore, the present invention provides: a method for manufacturing a connection structure, which is a method for manufacturing the connection structure, and includes: disposing the conductive assembly between the first substrate and the second substrate; and heating the conductive assembly to form the connection structure.

Furthermore, the present invention provides: a laminate comprising: a substrate; and a coating layer covering the substrate; wherein the coating layer is formed of the conductive composite.

Furthermore, the present invention provides: a method for manufacturing a laminate, which is a method for manufacturing the aforementioned laminate, and includes: depositing the aforementioned conductive composite on the aforementioned substrate; and heating the aforementioned conductive composite to form the aforementioned coating layer. [Effects of the Invention]

According to the present invention, a novel conductive assembly suitable for the installation of miniaturized electrodes can be provided.

The conductive composition of the first state of the present invention comprises: an organometallic salt and a resin.

The second state of the present invention is, for example, a conductive composition as in the first state, wherein the dissociation energy of the organometallic salt is less than 10,000 kJ/mol.

The third state of the present invention is, for example, a conductive composition as in the first or second state, wherein the aforementioned organometallic salt comprises both organic ions and metal ions.

The fourth state of the present invention is, for example, a conductive composition as in the third state, wherein the aforementioned organic ions have at least one selected from the group consisting of carboxylic acid groups and enol groups.

The fifth state of the present invention is, for example, a conductive composition as in the third or fourth state, wherein the metal ions comprise at least one selected from the group consisting of gold ions, silver ions, copper ions, nickel ions, tin ions and aluminum ions.

The sixth embodiment of the present invention is, for example, a conductive composition of any one of the first to fifth embodiments, wherein the resin comprises a thermosetting resin.

The seventh embodiment of the present invention is, for example, a conductive composition as in the sixth embodiment, wherein the thermosetting resin comprises an epoxy resin.

The eighth embodiment of the present invention is, for example, a conductive composition as in the sixth or seventh embodiment, wherein the thermosetting resin comprises liquid epoxy resin and solid epoxy resin.

The ninth state of the present invention is, for example, a conductive composition of any one of the first to eighth states, which further comprises an acid.

The 10th state of the present invention is, for example, a conductive composition as in the 9th state, wherein the acid comprises an organic acid.

The 11th state of this invention is, for example, a conductive composition like the 9th or 10th state, wherein the acid dissociation constant pKa of the above acid does not reach 5.3.

The conductive sheet of the 12th state of the present invention comprises: a conductive assembly of any one of the 1st to 11th states.

The 13th embodiment of the present invention comprises: a first substrate having a first electrode; a second substrate having a second electrode; and a connection member connecting the first substrate and the second substrate; and the connection member being formed of a conductive composite as described in any of the 1st to 11th embodiments.

The method for manufacturing the 14th aspect of the present invention is a method for manufacturing the 13th aspect of the connection structure, and includes: disposing the conductive assembly between the first substrate and the second substrate; and heating the conductive assembly to form the connection structure.

The laminate of the 15th embodiment of the present invention comprises: a substrate; and a coating layer covering the substrate; wherein the coating layer is formed of a conductive composition as described in any one of the 1st to 11th embodiments.

The method for manufacturing the 16th state of the present invention is a method for manufacturing a laminate as in the 15th state, and includes: disposing the conductive composite on the substrate; and heating the conductive composite to form the coating layer.

The present invention will now be described in detail, but the purpose of the following description is not to limit the present invention to a particular implementation.

<Implement of Conductive Composite> The conductive composite of this embodiment comprises an organometallic salt and a resin. The conductive composite is typically an anisotropic conductive composite suitable for substrate mounting, etc. In particular, the conductive composite, by comprising an organometallic salt, is suitable for mounting miniaturized electrodes.

In conductive compounds, organometallic salts can be dispersed in resins and are also miscible with resins. However, organometallic salts can partially aggregate in resins, and the aggregated organometallic salts can also have a particle shape.

(Organic metal salts) Organometal salts are typically salts containing both organic and metal ions. The dissociation energy of organometal salts is preferably below 10,000 kJ/mol. Lower dissociation energies in organometal salts allow for setting lower heating temperatures for the conductive components during installation. The dissociation energy of organometal salts is preferably below 8,000 kJ/mol, but can be below 5,000 kJ/mol, 3,500 kJ/mol, 3,000 kJ/mol, 1,000 kJ/mol, 800 kJ/mol, and even below 700 kJ/mol. The lower limit of the dissociation energy of organometallic salts is, for example, above 100 kJ/mol, above 300 kJ/mol, and even above 500 kJ/mol. In particular, organometallic salts with dissociation energies of 300–800 kJ/mol can be ionized at low temperatures, and the resulting metal ions have higher mobility within the resin, making them suitable for low-temperature installation.

In this specification, the dissociation energy of an organometallic salt refers to the energy required to dissociate the various ions (typically organic and metal ions) contained in the organometallic salt. The dissociation energy of an organometallic salt is, for example, equivalent to the sum of the energies _Em of the metal ions and the energies _O of the organic ions, minus the energy _Es of the organometallic salt (E _M + E _O - _Es ). Furthermore, the values of energies _Em , _O , and _Es can be calculated using quantum chemical calculations.

The organic ions contained in organometallic salts are typically anions and have a functional group X containing a negative charge. Examples of functional group X include carboxylate ( ^-COO- ) and enol (-CR=C( ^-O- )R: R is a hydrogen atom or any substituent). Among the organic ions, functional group X preferably has at least one selected from the group consisting of carboxylate and enol, and more preferably has a carboxylate.

There is no particular limitation on the number of functional groups X contained in the organic ion, for example, it can be 1 to 5, or it can be 1 to 3. It is preferred that the organic ion contains 1 functional group X.

The organic ion is preferably formed by replacing at least one hydrogen atom in the hydrocarbon compound with a functional group X. The hydrocarbon compound may also have other substituents besides the functional group X. Examples of other substituents include halogens, hydroxyl groups, and ketone groups. Examples of halogens include fluorine, chlorine, bromine, and iodine.

The hydrocarbon compound has, for example, 1 to 10 carbon atoms, 1 to 5 carbon atoms, and even 1 to 3 carbon atoms. The hydrocarbon compound can be linear or branched. Alkanes are preferred. Examples of alkanes include methane, ethane, and propane. Furthermore, the hydrocarbon compound may contain aromatic rings or other ring structures, or it may not contain any ring structures. Specific examples of aromatic rings include benzene rings.

Specific examples of organic ions containing a carboxylate group as a functional group X include lactate ions, acetate ions, trifluoroacetate ions, formate ions, citrate ions, and benzoate ions. Specific examples of organic ions containing an enol group as a functional group X include acetylacetone ions.

The metal ions contained in organometallic salts are typically cations. The valence of the metal ions can be, for example, 1 to 4, or 1 to 2.

Metal ions may be appropriately selected, for example, depending on the purpose of the connection structure, the type of substrate, and the manufacturing conditions of the connection structure, as described below. Preferably, they include at least one of the group consisting of gold ions, silver ions, copper ions, nickel ions, tin ions, and aluminum ions.

Specific examples of organometallic salts include: silver lactate, silver benzoate, silver trifluoroacetate, silver trisilver citrate hydrate, silver acetoacetone, copper(II) acetoacetone, tin(II) acetate, etc.

The content of organometallic salts in the conductive composition is, for example, 0.1 wt% or more, and may be 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, and may even be 10 wt% or more. The upper limit of the content of organometallic salts is, for example, 60 wt% or less, and may be 40 wt% or less, and may even be 20 wt% or less.

(Resin) As a resin, it is known in the field of anisotropic conductive compounds, such as thermosetting resins and thermoplastic resins. The resin preferably includes thermosetting resins. Thermosetting resins preferably include epoxy resins, and more preferably include both liquid epoxy resins and solid epoxy resins. However, thermosetting resins may also consist only of liquid epoxy resins. Furthermore, in this specification, "liquid" means a substance that is liquid at atmospheric pressure (101.325 kPa) and at 20°C, and "solid" means a substance that is solid at atmospheric pressure and at 20°C. Resin can also be a water-soluble resin that is soluble in water.

Examples of epoxy resins (thermosetting epoxy resins) include: bisphenol type epoxy resins (e.g., bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin), phenolic varnish type epoxy resins (e.g., phenolic varnish type epoxy resin, cresol phenolic varnish type epoxy resin, and biphenyl type epoxy resin), naphthalene type epoxy resin, fumonisin type epoxy resin (e.g., bisarylfumonisin type epoxy resin), triphenylmethane type epoxy resin (e.g., trihydroxyphenylmethane type epoxy resin), etc.

Furthermore, the resins contained in the conductive components are not limited to epoxy resins. Other resins besides epoxy resins include: acrylic resins, polyester resins, amino resins, urea resins, carbamate resins, butyraldehyde resins, polyvinyl alcohol resins, phenolic resins, polyamide resins, melamine resins, etc.

The conductive composition preferably comprises both liquid resin (liquid resin) and solid resin (solid resin). The ratio of the solid resin content (wt%) in the conductive composition to the total content (wt%) of the liquid resin (wt%) and the solid resin (wt%) is, for example, 50% or more, and can be 60% or more, 70% or more, 80% or more, and even 90% or more. This ratio can also be 100%. The higher this ratio, the less likely the material in the conductive sheet will shrink over time relative to the release sheet when the conductive composition is coated on the release sheet to produce a conductive sheet.

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, and may even be 80 wt% or more. The upper limit of the resin content is, for example, 99 wt% or less, and may also be 95 wt% or less.

The (acid) conductive compound is preferably acid-containing. Depending on the acid, the heating temperature of the conductive compound during installation can be set lower.

The acid dissociation constant pKa (especially the first acid dissociation constant) is preferably not greater than 5.3. The pKa of the acid is preferably below 5.0, but can be below 4.7, 4.5, 4.0, 3.5, or even below 2.5. The lower the pKa of the acid, the more readily organometallic salts can be ionized at low temperatures, thus making it suitable for low-temperature installations. The lower limit of the acid's pKa is, for example, above 1.5. In this specification, pKa refers to the value in water at 25°C.

Examples of acids include organic acids and inorganic acids. Acids are preferably organic acids. Organic acids are typically compounds containing acidic groups such as carboxyl groups. The number of acidic groups in an organic acid is, for example, 1 or more, and can be 1 to 3, or even 1 to 2. Organic acids preferably contain one acidic group.

Organic acids are preferably formed by replacing at least one hydrogen atom in a hydrocarbon compound with an acidic group. The hydrocarbon compound may also have other substituents besides the acidic group. Examples of hydrocarbon compounds or other substituents mentioned above can be cited in relation to organometallic salts.

The hydrocarbon compounds are preferably alkanes or alkenes. Examples of alkanes include organometallic salts as described above. Examples of alkenes include ethylene and propylene.

Specific examples of organic acids include acrylic acid, trifluoromethacrylic acid, methacrylic acid, lactic acid, glutaric acid, and formic acid.

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

The acid content in the conductive composition may be, for example, 10 wt% to 60 wt%, or 30 wt% to 50 wt%. The conductive composition may also be acid-free.

(Other Components) Conductive compounds may further include components other than organometallic salts, resins, and acids. Examples of other components include: solvents, hardeners, thixotropic agents, defoamers, antioxidants, thickeners, chelating agents, reducing agents, pH buffers, etc.

The content of other components in the conductive composition may be, for example, less than 30 wt%, less than 10 wt%, less than 5 wt%, less than 1 wt%, or even less than 0.1 wt%. The conductive composition may be substantially free of other components (especially solvents).

<Implement of Conductive Sheet> Figure 1 is a cross-sectional view schematically showing the conductive sheet 1 of this embodiment. The conductive sheet 1 includes the aforementioned conductive composition. Specifically, the conductive sheet 1 has the same composition as the conductive composition, except that it does not contain solvent. However, the conductive sheet 1 may contain a small amount of solvent from the conductive composition. Furthermore, when the conductive composition includes a thermosetting resin, the thermosetting resin is typically present in an uncured state in the conductive sheet 1.

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

The conductive sheet 1 can be manufactured, for example, by the following method. First, a release sheet is prepared, and a conductive composition is coated on the release sheet. By drying the obtained coating film, the conductive sheet 1 is formed on the release sheet. The conductive sheet 1 can be obtained by peeling off the release sheet from the conductive sheet 1.

<Implement of the Connecting Structure> Figure 2A is a cross-sectional view schematically showing the connecting structure 100 of this embodiment. The connecting structure 100 includes a first substrate 20, a second substrate 30, and a connecting 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 connecting member 10 is formed of the above-described conductive composite and connects the first substrate 20 and the second substrate 30. The first substrate 20, the connecting member 10, and the second substrate 30 are arranged sequentially in the lamination direction Y.

The first substrate 20 has a main surface (the surface of the first substrate 20 with the largest area) facing the connecting member 10, and a first electrode 21 is disposed on the main surface. The first electrode 21 may be disposed in a pattern on the first substrate 20. Furthermore, a plurality of first electrodes 21 may be disposed on the first substrate 20. In the example of FIG. 2A, a plurality of first electrodes 21a, 21b and 21c are disposed on the first substrate 20. Moreover, the width (line) of the first electrode 21 may be 20 μm or less, or may be 10 μm or less. The distance (spacing) between two adjacent first electrodes 21 may be 20 μm or less, or may be 10 μm or less. The combination of line and spacing (L/S: line and spacing) of the first electrode 21 can be less than 20 μm/less, or less than 10 μm/less.

Similar to the first substrate 20, the second substrate 30 has a main surface facing the connecting member 10, on which a second electrode 31 is disposed. The second electrode 31 faces the first electrode 21, and the electrodes 21 and 31 are arranged along the lamination direction Y. Specifically, the second electrode 31 overlaps with the first electrode 21 in a top view. The second electrode 31 may be patterned 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. A plurality of second electrodes 31a, 31b and 31c are respectively opposite to a plurality of first electrodes 21a, 21b and 21c. Furthermore, the L/S ratio of the second electrode 31 is typically the same as that of the first electrode 21.

The materials used for the first electrode 21 and the second electrode 31 can be those known to the public. The materials for the first electrode 21 and the second electrode 31 are, for example, metals such as copper and nickel.

Specific examples of the first substrate 20 and the second substrate 30 equipped with electrodes include: electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes; wiring substrates such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flex boards, glass epoxy boards, and glass substrates. Preferably, one of the first substrate 20 and the second substrate 30 is an electronic component, and the other is a wiring substrate.

The connecting component 10 has a conductive portion 6 and an insulating portion 7. The conductive portion 6 is directly connected to the first electrode 21 disposed on the first substrate 20 and the second electrode 31 disposed on the second substrate 30, thereby electrically connecting them. According to the conductive portion 6, conductivity is achieved in the Y-direction of the lamination.

The conductive portion 6 preferably overlaps with each of the first electrode 21 and the second electrode 31 when viewed from above. When the first electrode 21 and the second electrode 31 are arranged in a patterned configuration, the conductive portion 6 is preferably also arranged in a patterned configuration. Furthermore, the connecting component 10 may have a plurality of conductive portions 6. In the example of FIG. 2A, the connecting component 10 has a plurality of conductive portions 6a, 6b, and 6c. Conductive portion 6a is directly connected to each of the first electrode 21a and the second electrode 31a, conductive portion 6b is directly connected to each of the first electrode 21b and the second electrode 31b, and conductive portion 6c is directly connected to each of the first electrode 21c and the second electrode 31c.

The conductive part 6 preferably contains a metal as its main component. The metal contained in the conductive part 6 is typically an organometallic salt derived from a conductive compound. Furthermore, in this specification, "main component" means the component that is contained in the largest proportion by weight in the mentioned component. The conductive part 6 may also contain other components besides metal (e.g., resin).

The insulating portion 7 surrounds the conductive portion 6, filling the space between the first substrate 20 and the second substrate 30 where the conductive portion 6 does not exist. The insulating portion 7 is in direct contact with the surfaces of the first substrate 20 (where the first electrode 21 is not disposed) and the second substrate 30 (where the second electrode 31 is not disposed). The insulating portion 7 ensures insulation in the planar direction X, which is orthogonal to the lamination direction Y.

The insulating portion 7 preferably contains resin as its main component. The resin contained in the insulating portion 7 can be the same as the resin of the conductive compound, or it can be a cured product obtained by curing the resin of the conductive compound (especially thermosetting resin). Furthermore, the insulating portion 7 may also contain other components besides resin (such as organometallic salts).

The manufacturing method of the connection structure 100 of this embodiment includes, for example,: disposing a conductive assembly between the first substrate 20 and the second substrate 30; and heating the conductive assembly to form the connection structure 10.

In detail, the connection structure 100 can be manufactured by the following method. First, as shown in FIG. 2B, a conductive sheet 1 containing a conductive composition is disposed between the first substrate 20 and the second substrate 30. However, the conductive composition can also be disposed between the first substrate 20 and the second substrate 30 using known coating or printing methods, without using the conductive sheet 1.

Next, the conductive sheet 1 containing the conductive composition is heated. Heating of the conductive sheet 1 can be performed using a reflow oven or a baking oven. The heating temperature of the conductive sheet 1 can be appropriately adjusted according to the composition of the conductive composition, for example, from 30°C to 300°C. The heating temperature of the conductive sheet 1 can be below 250°C, or below 200°C, below 180°C, below 150°C, below 130°C, below 100°C, below 80°C, and even below 50°C. The heating time of the conductive sheet 1 is not particularly limited, for example, from 1 second to 10 minutes.

When the conductive sheet 1 is heated, metal from the organometallic salts in the conductive composition is deposited on the surfaces of the first electrode 21 and the second electrode 31, forming a conductive portion 6. The metal deposition on the electrodes can be generated by an oxidation-reduction reaction between the metal ions contained in the organometallic salts and the electrode material. No metal deposition occurs 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, thus forming an insulating portion 7. Furthermore, when the conductive sheet 1 is heated, it can be softened, causing the first electrode 21 and the second electrode 31 to embed into the interior of the conductive sheet 1. When the conductive composition contains a thermosetting resin, it is preferable to heat the conductive sheet 1 to harden the thermosetting resin.

When the conductive sheet 1 is heated, stress can also be applied to the laminate of the first substrate 20, the conductive sheet 1 and the second substrate 30 in the lamination direction Y, thereby pressing them together. According to this operation, there is a tendency to increase the strength of the connecting structure 100.

As described above, by heating the conductive sheet 1, a connecting component 10 having a conductive portion 6 and an insulating portion 7 is formed, thereby obtaining a connecting structure 100. Furthermore, in the conductive assembly of this embodiment, an organometallic salt is included instead of the previous solder particles. The metal ions contained in the organometallic salt are not only much smaller than the solder particles, but also can be deposited on the electrode by a redox reaction. Therefore, according to the conductive assembly of this embodiment, even when using miniaturized electrodes (e.g., electrodes with L/S of 20 μm or less/20 μm or less), the conductive portion 6 can be reliably formed on the electrode, making it suitable for installation.

<Implement of the Laminate> Figure 3A is a schematic cross-sectional view of the laminate 200 according to this embodiment. The laminate 200 includes a substrate 40 and a cover layer 15. The cover layer 15 is formed of the aforementioned conductive composite and covers the substrate 40. Specifically, the cover layer 15 covers one main surface of the substrate 40. The cover layer 15 may cover the entire main surface of the substrate 40 or only a portion of the main surface of the substrate 40.

Electrodes 41 are disposed on substrate 40. Electrodes 41 are disposed, for example, on the main surface of substrate 40 opposite to the coating layer 15. Electrodes 41 may be disposed in a pattern on substrate 40. Furthermore, a plurality of electrodes 41 may be disposed on substrate 40. In the example of FIG. 3A, a plurality of electrodes 41a, 41b and 41c are disposed on substrate 40. Examples of substrate 40 and electrodes 41 can be given with respect to the first substrate 20 and the first electrode 21 described above.

The coating layer 15 has, for example, a conductive portion 16 and an insulating portion 17. The conductive portion 16 of the coating layer 15 is directly connected to the electrode 41 disposed on the substrate 40, thereby being electrically connected to the electrode 41. The conductive portion 16 extends in the Y direction of the lamination of the substrate 40 and the coating layer 15.

The conductive portion 16 preferably overlaps with the electrode 41 when viewed from above. When the electrode 41 is arranged in a patterned configuration, the conductive portion 16 is also preferably arranged in a patterned configuration. Furthermore, the coating layer 15 may have a plurality of conductive portions 16. In the example of FIG. 3A, the coating layer 15 has a plurality of conductive portions 16a, 16b, and 16c. Conductive portion 16a is directly connected to electrode 41a, conductive portion 16b is directly connected to electrode 41b, and conductive portion 16c is directly connected to electrode 41c. Moreover, the material of the conductive portion 16 is the same as that described above regarding the connecting component 10.

The insulating portion 17 surrounds the conductive portion 16 and is in direct contact with the surface of the substrate 40 without electrodes 41. Furthermore, the material of the insulating portion 17 is the same as that described above regarding the connecting component 10.

The manufacturing method of the laminate 200 in this embodiment includes, for example,: depositing a conductive component on a substrate 40; and heating the conductive component to form a coating layer 15.

In detail, the laminate 200 can be manufactured by the following method. First, as shown in FIG3B, a conductive sheet 1 containing a conductive composition is disposed on the substrate 40. However, the conductive composition can also be disposed on the substrate 40 using known coating or printing methods without using the conductive sheet 1.

Next, the conductive sheet 1 containing the conductive composition is heated. The heating conditions for the conductive sheet 1 can be exemplified by those described above regarding the connecting structure 100. When the conductive sheet 1 is heated, metal from the organometallic salt in the conductive composition is deposited on the surface of the electrode 41, and the deposit forms a conductive portion 16. The metal deposition on the electrode can be generated by a redox reaction between the metal ions contained in the organometallic salt and the electrode material. 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. Furthermore, when the conductive sheet 1 is heated, the conductive sheet 1 can be softened, allowing the electrode 41 to be embedded inside the conductive sheet 1. In cases where the conductive composition contains a thermosetting resin, it is preferable to heat the conductive sheet 1 to harden the thermosetting resin.

When the conductive sheet 1 is heated, stress can also be applied to the substrate 40 and the laminate of the conductive sheet 1 in the lamination direction Y, thereby pressing them together. According to this operation, there is a tendency to increase the strength of the laminate 200.

As described above, by heating the conductive sheet 1, a coating layer 15 having a conductive portion 16 and an insulating portion 17 is formed, thereby obtaining a laminate 200.

Furthermore, when the conductive composition contains thermoplastic resin or water-soluble resin, the insulating portion 17 can be removed using a solvent such as water or an organic solvent. In this case, the coating layer 15 may not have the insulating portion 17, or it may be composed solely of the conductive portion 16. [Example]

The invention will now be described in more detail by way of embodiments and comparative examples, but the invention is not limited thereto.

(Example 1) First, 50 parts by weight of liquid epoxy resin (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Co., Ltd., jER828) are added to 10 parts by weight of silver trifluoroacetate salt as an organometallic salt, and stirred until homogeneous. Then, 50 parts by weight of solid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-017) and acetone are added to the obtained mixture. This yields a conductive composite with a solid content of 70 wt%. Next, using a dressing applicator, the conductive composite is applied to a peel-off pad and dried at 60°C for 5 minutes. In this way, the conductive sheet material (10 μm thick) of Embodiment 1 is obtained.

(Examples 2-33) The types and amounts of organometallic salts or resins are changed as shown in Tables 1-3. Otherwise, the conductive sheets of Examples 2-33 are obtained by the same method as in Example 1. Furthermore, in Examples 8-33, the acid is also added to the mixture along with the solid epoxy resin and acetone.

(Comparative Example 1) First, 50 parts by weight of liquid epoxy resin (bisphenol A type epoxy resin, Mitsubishi Chemical Co., Ltd., jER828) were added to 175 parts by weight of solder particles (SAC305, Sn96.5Ag3.0Cu0.5, manufactured by Mitsui Metals Industry Co., Ltd., average particle size (D50) 7 μm), and stirred until homogeneous. Then, 50 parts by weight of solid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-017), 15 parts by weight of glutaric acid (manufactured by Fujifilm and Hikari Junya Co., Ltd.), and acetone were mixed into the obtained mixture. This yielded a conductive composite with a solid content of 70 wt%. Next, using a dressing applicator, the conductive composition was applied to the peeled-off pad and dried at 60°C for 5 minutes. This yielded the conductive sheet (10 μm thick) of Comparative Example 1.

(Comparative Example 2) SAC305 (Sn96.5Ag3.0Cu0.5, manufactured by Mitsui Metals Corporation, with an average particle size (D50) of 10 μm) was used as solder particles. Otherwise, the conductive sheet material (thickness 10 μm) of Comparative Example 2 was obtained by the same method as Comparative Example 1.

[Evaluation] (Dissociation Energy of Organometallic Salts) The dissociation energy of the organometallic salts used in the embodiments was determined by the following method. First, a three-dimensional structure was generated from the SMILE notation molecular structure of the organometallic salt using the RDkit module of Python. Silver ions (Ag ⁺ ) were replaced with morium ions (Rb ⁺ ), and tin ions (Sn2 ⁺ ) were replaced with copper ions (Cu2 ⁺ ). The resulting three-dimensional molecular structure was arranged under periodic boundary conditions of 4×4×3 ^nm3 . Using this structure as the initial structure, molecular dynamics calculations of the NVE ensemble were performed at 800 K and 1 ns. Structures were extracted every 5 ps from the calculated trajectories, and structural optimization calculations were performed on all of them. From the 200 optimized structures obtained, the structure with the lowest energy (the stable structure) was extracted. Furthermore, the molecular dynamics calculations and structure optimization calculations were performed using the Forcite module of Materials Studio, manufactured by Dassault Systemes. The COMPASS III force field was used in the molecular dynamics calculations.

Next, for the obtained stable structure, the substituted metal ions are replaced with the original metal ions. The substituted structure is used as the initial structure, and structure optimization calculations are performed. For the obtained optimized structure, and the organic ionic elements and metal ionic elements extracted from the optimized structure, an energy assessment based on single-point calculations is performed to determine their respective energies. The value ( _EM + _EO - _ES ) obtained by subtracting the energy Es of the organometallic salt from the sum of the energy _Em of the metal ionic element and the energy _EO of the organic ionic element is determined as the dissociation energy of the organometallic salt. Furthermore, the quantum chemical calculations are performed using a Gaussian ₁₆ manufactured by Gaussian Corporation. For the function system and the base system, B3LYP/LANL2DZ is used, with D3 modifications implemented by Grimme et al.

(Installation Evaluation) For the conductive sheets in the embodiments and comparative examples, the installation evaluation of the miniaturized electrodes was conducted using the following method. First, a virtual wafer (substrate) with 700 electrodes was prepared. The substrate dimensions were 10 mm in length × 10 mm in 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).

Next, a conductive sheet measuring 10 mm x 10 mm was placed on the substrate in contact with the electrodes and bonded under vacuum conditions at 50°C. Then, an alkali-free glass plate measuring 10 mm x 10 mm was placed on the conductive sheet and bonded further. The resulting sample was then mounted in a vacuum pressure reflow apparatus (manufactured by SST International, Model 1200 Table Top Furnace) and placed in a vacuum atmosphere.

Next, the test piece was heated at a rate of 100°C/min, using the temperatures recorded in Tables 1-4 as the maximum temperature. During this process, the test piece was pressurized to 4.5 atmospheres under nitrogen. The test piece was heated at the maximum temperature for 2 minutes. This heat treatment formed a coating layer on the substrate. The surface of the coating layer was observed from the alkali-free glass side using an optical microscope (Keyence Corporation, VHX-8000). Specifically, seven areas were observed under a microscope at 500x magnification. As observation positions, using one corner of the conductive sheet as a reference, select the following positions: P1 (2.5 mm x 2.5 mm), P2 (2.5 mm x 7.5 mm), P3 (5.0 mm x 2.5 mm), P4 (5.0 mm x 5.0 mm), P5 (5.0 mm x 7.5 mm), P6 (7.5 mm x 2.5 mm), and P7 (7.5 mm x 7.5 mm).

At each observation point, confirm whether a conductive portion (or accumulation) is formed on each electrode. Those with conductive portions are rated as good (○). Calculate the ratio of the number of good ratings to the total number of electrodes observed, and conduct an installation evaluation based on the following criteria: • Evaluation Criteria 1: The above ratio is 30% or less. 2: The above ratio is more than 30% but less than 60%. 3: The above ratio is more than 60% but less than 90%. 4: The above ratio is more than 90% but less than 100%.

Furthermore, the installation evaluation uses a virtual wafer configured with copper electrodes as electrodes and a virtual wafer configured with nickel electrodes.

(Conductivity Test) Using the conductive sheets of the embodiments and comparative examples, a connection structure was fabricated by the following method to evaluate the conductivity.

(1) Fabrication of the Connector Structure First, prepare two FPC substrates with Cu electrodes (electrode diameter 100 μm, electrode spacing 100 μm). Next, peel the stripper backing from the fabricated conductive sheet and place the conductive sheet between the two FPC substrates. At this time, use a high-precision die bonding device (manufactured by Finetech, named "FINEPLACER lambda 2") to adjust the electrodes of the opposing FPC substrates so that their positions are aligned with the conductive sheet.

Next, the laminate is placed in a vacuum pressure reflow apparatus (manufactured by SST Vacuum Reflow System, named "Model1200 Table Top Furnace") and a vacuum is applied. Then, under nitrogen pressure of 4.5 atmospheres, it is heated to the temperatures recorded in Tables 1-3 at a heating rate of 100°C/min and held for 15 minutes to obtain the connection structure.

(2) Continuity Assessment For this connection structure, a digital multimeter (named "PC500a", manufactured by Sanwa Electric Measurement Co., Ltd.) was used to measure the resistance between the opposing electrodes, and the electrical connection (continuity) of the opposing electrodes was assessed based on the following criteria: 2: Resistance can be measured (resistance measured as a positive value). 1: Resistance cannot be measured (overload of the multimeter's measurement range).

[Table 1] Dissociation energy [kJ/mol] pKa Implementation Examples 1 2 3 4 5 6 7 8 9 10 Conductive composition Organic metal salt blending amount [parts by weight] Silver trifluoroacetate 620 - 10 - - - - - - - - - Silver benzoate 701 - - 10 - - - - - - - - Trisilver Citric Acid Hydrate 706 - - - 10 - - - - - - - silver lactate 721 - - - - 10 - - - - - - Acetate acetone silver salt 756 - - - - - 10 - - 10 - - Acetyl acetone copper(II) salt 3393 - - - - - - 10 - - 10 - Tin(II) acetate 2838 - - - - - - - 10 - - 10 Acid preparation amount [parts by weight] methacrylic acid - 4.7 - - - - - - - 90 90 90 Resin formulation [parts by weight] jER828 - - 50 50 50 50 50 50 50 50 50 50 YD-017 - - 50 50 50 50 50 50 50 50 50 50 Installation evaluation Heating temperature [°C] 250 Copper electrode (L/S = 10 μm/10 μm) 4 4 4 4 4 - - - - - Nickel electrode (L/S = 10 μm/10 μm) 4 4 4 4 4 3 3 - - - Heating temperature [°C] 170 Copper electrode (L/S = 10 μm/10 μm) 4 4 4 4 - - - 4 - - Nickel electrode (L/S = 10 μm/10 μm) 4 4 4 4 - - - 4 4 4 Continuity test Heating temperature [°C] 250 FPC substrate (L/S = 100 μm/100 μm) 2 2 2 2 2 - - - - - Heating temperature [°C] 170 FPC substrate (L/S = 100 μm/100 μm) 2 2 2 2 - - - 2 - -

[Table 2] Dissociation energy [kJ/mol] pKa Implementation Examples 11 12 13 14 15 16 17 18 19 20 twenty one Conductive composition Organic metal salt blending amount [parts by weight] Silver trifluoroacetate 620 - 10 - - - 10 - - - - - - Silver benzoate 701 - - 10 - - - 10 - - - - - Trisilver Citric Acid Hydrate 706 - - - 10 - - - 10 - - - - silver lactate 721 - - - - 10 - - - 10 - - - Acetate acetone silver salt 756 - - - - - - - - - 10 - - Acetyl acetone copper(II) salt 3393 - - - - - - - - - - 10 - Tin(II) acetate 2838 - - - - - - - - - - - 10 Acid preparation amount [parts by weight] lactic acid - 3.8 - - - - 90 90 90 90 90 90 90 methacrylic acid - 4.7 90 90 90 90 - - - - - - - Resin formulation [parts by weight] jER828 - - 50 50 50 50 50 50 50 50 50 50 50 YD-017 - - 50 50 50 50 50 50 50 50 50 50 50 Installation evaluation Heating temperature [°C] 50 Copper electrode (L/S = 10 μm/10 μm) 4 4 4 4 4 4 4 4 4 - - Nickel electrode (L/S = 10 μm/10 μm) 4 4 4 4 4 4 4 4 4 4 4 Continuity test Heating temperature [°C] 50 FPC substrate (L/S = 100 μm/100 μm) 2 2 2 2 2 2 2 2 2 - -

[Table 3] Dissociation energy [kJ/mol] pKa Implementation Examples twenty two twenty three twenty four 25 26 27 28 29 30 31 32 33 Conductive composition Organic metal salt blending amount [parts by weight] Silver trifluoroacetate 620 - 10 - - - - - - 10 10 10 10 10 Silver benzoate 701 - - 10 - - - - - - - - - - Trisilver Citric Acid Hydrate 706 - - - 10 - - - - - - - - - silver lactate 721 - - - - 10 - - - - - - - - Acetate acetone silver salt 756 - - - - - 10 - - - - - - - Acetyl acetone copper(II) salt 3393 - - - - - - 10 - - - - - - Tin(II) acetate 2838 - - - - - - - 10 - - - - - Acid preparation amount [parts by weight] Trifluoromethacrylic acid - 2.5 90 90 90 90 90 90 90 - - - - - lactic acid - 3.8 - - - - - - - 90 90 90 90 90 Resin formulation [parts by weight] jER828 - - 50 50 50 50 50 50 50 40 30 20 10 - YD-017 - - 50 50 50 50 50 50 50 60 70 80 90 100 Installation evaluation Heating temperature [°C] 50 Copper electrode (L/S = 10 μm/10 μm) 4 4 4 4 4 - - 4 4 4 3 3 Nickel electrode (L/S = 10 μm/10 μm) 4 4 4 4 4 4 4 4 4 4 3 3 Continuity test Heating temperature [°C] 50 FPC substrate (L/S = 100 μm/100 μm) 2 2 2 2 2 - - 2 2 2 2 2

[Table 4] pKa Comparative example 1 2 Conductive composition Solder particle mixing amount [parts by weight] SAC305 (D50: 7 μm) - 175 - SAC305 (D50: 10 μm) - - 175 Acid preparation amount [parts by weight] glutaric acid 4.5 15 15 Resin formulation [parts by weight] jER828 - 50 50 YD-017 - 50 50 Installation evaluation Heating temperature [°C] 250 Copper electrode (L/S = 10 μm/10 μm) 2 2 Nickel electrode (L/S = 10 μm/10 μm) 2 2 Heating temperature [°C] 170 Copper electrode (L/S = 10 μm/10 μm) 1 1 Nickel electrode (L/S = 10 μm/10 μm) 1 1 Heating temperature [°C] 50 Copper electrode (L/S = 10 μm/10 μm) 1 1 Nickel electrode (L/S = 10 μm/10 μm) 1 1

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

Furthermore, the organometallic salts and acids used in the embodiments are all manufactured by Sigma Aldrich.

As shown in Tables 1-4, the conductive composition of the embodiments containing organometallic salts and resins exhibits better installation evaluation results compared to the conductive composition of the comparative examples. Based on these results, the conductive composition of the embodiments can be considered suitable for the installation of miniaturized electrodes. [Industrial Applicability]

The conductive assembly of this embodiment can be used for the installation of miniaturized electrodes.

1: Conductive sheet; 6, 6a, 6b, 6c: Conductive portion; 7: Insulating portion; 10: Connecting component; 15: Coating layer; 16, 16a, 16b, 16c: Conductive portion; 17: Insulating portion; 20: First substrate; 21, 21a, 21b, 21c: First electrode; 30: Second substrate; 31, 31a, 31b, 31c: Second electrode; 40: Substrate; 41, 41a, 41b, 41c: Electrode; 100: Connecting structure; 200: Laminated body; X: Planar direction; Y: Lamination direction.

Figure 1 is a cross-sectional view schematically showing a conductive sheet of one embodiment of the present invention. Figure 2A is a cross-sectional view schematically showing a connecting structure of one embodiment of the present invention. Figure 2B is a diagram illustrating the manufacturing method of the connecting structure of Figure 2A. Figure 3A is a cross-sectional view schematically showing a laminate of one embodiment of the present invention. Figure 3B is a diagram illustrating the manufacturing method of the laminate of Figure 3A.

1: Conductive sheet

Claims (16)

A conductive composition comprising an organometallic salt and a resin. For example, in the conductive composition of claim 1, the dissociation energy of the aforementioned organometallic salt is below 10,000 kJ/mol. The conductive composition of claim 1, wherein the aforementioned organic metal salt comprises both organic ions and metal ions. The conductive composition of claim 3, wherein the aforementioned organic ions have at least one selected from the group consisting of carboxylic acid groups and enol groups. The conductive composition of claim 3, wherein the metal ions comprise at least one selected from the group consisting of metal ions, silver ions, copper ions, nickel ions, tin ions and aluminum ions. The conductive composition of claim 1, wherein the resin comprises a thermosetting resin. The conductive composition of claim 6, wherein the thermosetting resin comprises an epoxy resin. The conductive composition of claim 6, wherein the thermosetting resin comprises liquid epoxy resin and solid epoxy resin. The conductive composition of claim 1 further includes an acid. As in claim 9, the conductive composition wherein the acid comprises an organic acid. For example, in the conductive composition of claim 9, the acid dissociation constant pKa of the aforementioned acid does not reach 5.3. A conductive sheet comprising a conductive assembly as described in any of claims 1 to 11. A connection structure comprising: a first substrate having a first electrode disposed thereon; a second substrate having a second electrode disposed thereon; and a connection member connecting the first substrate and the second substrate; wherein the connection member is formed of a conductive assembly as described in any one of claims 1 to 11. A method for manufacturing a connection structure, comprising: disposing the conductive assembly between the first substrate and the second substrate; and heating the conductive assembly to form the connection structure. A laminate comprising: a substrate; and a coating layer covering the substrate; wherein the coating layer is formed of a conductive assembly as described in any one of claims 1 to 11. A method for manufacturing a laminate, which is a method for manufacturing a laminate as claimed in claim 15, and includes: disposing the conductive assembly on the substrate; and heating the conductive assembly to form the coating layer.