Conductive resin composition, joining sheet, conductive resin composition manufacturing method, joined body manufacturing method, and joined body

Abstract

The conductive resin composition includes acid-treated solder particles 5, a resin component, and a flux having a carboxyl group. The maximum value of the Mulliken charge of the carbon of the carboxyl group of the flux is 0.5850 or less.

Description

Technical Field

[0001] This invention relates to a conductive resin composition, a bonding sheet, a method for manufacturing a conductive resin composition, a method for manufacturing a bond, and a bond. More specifically, it relates to a conductive resin composition, a bonding sheet comprising the conductive resin composition, a method for manufacturing a conductive resin composition, a method for manufacturing a bond obtained using the conductive resin composition, and a bond having an adhesive layer as a cured product of the bonding sheet. Background Technology

[0002] Traditionally, bonding pads have been used to join terminals between two wiring circuit boards. These bonding pads are formed from a composition comprising solder particles, a curable resin, and flux.

[0003] The bonding pad is first placed between two wiring circuit boards. Next, the bonding pad is heated. This temporarily softens the curing resin, causing solder particles to gather and aggregate between the terminals (self-aggregation). Then, the curing resin cures around the solder. The aggregated solder solidifies upon subsequent cooling, forming a solder portion. Around the solder portion, the curing resin forms a cured resin portion.

[0004] As such a bonding sheet, for example, a conductive material containing solder particles, a thermosetting compound, and benzylamine glutarate as a flux (the maximum value of the Mulliken charge of the carbon in the carboxyl group of benzylamine glutarate is 0.5996) is known (see, for example, Example 1 of Patent Document 1).

[0005] Existing technical documents Patent documents Patent Document 1: International Publication No. 2019 / 124512 Summary of the Invention

[0006] The problem that the invention aims to solve However, in the conductive material of Patent Document 1, there is a situation where the flux reacts with the thermosetting compound. However, the reaction products of the flux and thermosetting compound decompose due to the unreacted flux, generating gas at this time. This gas can lead to the formation of pores, which is a problem.

[0007] The present invention provides a conductive resin composition capable of suppressing the formation of pores, a bonding sheet comprising the conductive resin composition, a method for manufacturing the conductive resin composition, a method for manufacturing a bonding body obtained using the conductive resin composition, and a bonding body having an adhesive layer as a cured product of the bonding sheet.

[0008] Methods for solving problems The present invention [1] is a conductive resin composition comprising acid-treated solder particles, resin components, and a flux having carboxyl groups, wherein the maximum value of the Mulliken charge of the carbon of the aforementioned carboxyl group in the aforementioned flux is 0.5850 or less.

[0009] The present invention [2] comprises the conductive resin composition described in [1] above, wherein the proportion of the aforementioned flux is more than 1 part by mass and less than 7 parts by mass relative to 100 parts by mass of the aforementioned acid-treated solder particles.

[0010] The present invention [3] comprises the conductive resin composition described in [1] or [2] above, wherein the aforementioned flux is a carboxylic acid.

[0011] The present invention [4] comprises the conductive resin composition described in [3] above, wherein the aforementioned flux is a dicarboxylic acid.

[0012] The present invention [5] includes a bonding sheet comprising the conductive resin composition described in any one of [1] to [4] above.

[0013] The present invention [6] is a method for manufacturing a conductive resin composition, comprising: The first step involves acid treating the solder particles using an acid treatment agent; and The second step involves mixing the acid-treated solder particles, resin components, and carboxyl-containing flux. The maximum value of the Mulliken charge of the carbon group of the aforementioned carboxyl group in the aforementioned flux is less than 0.585.

[0014] The present invention [7] includes a method for manufacturing the conductive resin composition described above [6], wherein the aforementioned acid treatment agent has a carboxyl group and the maximum value of the Mulliken charge of the carbon of the aforementioned carboxyl group exceeds 0.5850.

[0015] The present invention [8] includes a method for manufacturing a bonding body, comprising: a third step of preparing a plurality of substrates having a plurality of electrodes arranged in a planar direction; a fourth step of coating a conductive resin composition obtained by the manufacturing method described above [6] or [7] to prepare a bonding sheet; a fifth step of stacking the two substrates with the bonding sheet sandwiched between the electrodes of the two substrates to manufacture a laminate; and a sixth step of heating the laminate to melt the solder particles, thereby forming a columnar solder portion in a manner that electrically connects the electrodes of the two substrates, and curing the resin component.

[0016] The present invention [9] includes a method for manufacturing the joint described in [8] above, wherein the aforementioned sixth step is performed in a pressure oven.

[0017] The present invention

[10] includes a bonding body comprising: a first substrate having a plurality of first electrodes arranged in a planar direction; a second substrate having a plurality of second electrodes arranged in the aforementioned planar direction, the aforementioned second substrate being disposed at intervals in a thickness direction orthogonal to the aforementioned planar direction such that the aforementioned first electrodes and the aforementioned second electrodes are opposed to each other; and an adhesive layer sandwiched between the aforementioned first substrate and the aforementioned second substrate, electrically connecting the aforementioned first electrodes and the aforementioned second electrodes opposed to each other in the aforementioned thickness direction, and bonding the aforementioned first substrate and the aforementioned second substrate, the aforementioned adhesive layer being a cured product of the bonding sheet described in any one of [1] to [4] above, the aforementioned adhesive layer comprising a columnar solder portion for electrically connecting the aforementioned first electrodes and the aforementioned second electrodes opposed to each other in the aforementioned thickness direction and a cured resin.

[0018] Invention Effects Furthermore, in this conductive resin composition, the maximum value of the Mulliken charge on the carbon of the carboxyl group in the flux is 0.5850 or less. Therefore, the formation of pores can be suppressed.

[0019] Specifically, in conductive resin compositions, there are cases where the resin component reacts with the flux (e.g., ester formation reaction). However, if the reaction product of the resin component and flux (e.g., ester bond) is nucleophilically attacked by unreacted flux (anion), decomposition occurs, generating gas. This gas can lead to the undesirable situation of porosity. The ease with which this nucleophilic attack occurs depends on the force by which the reaction product of the resin component and flux attracts the unreacted flux and the amount of protons released from the unreacted flux.

[0020] If the maximum Mulliken charge of the carbon atom in the carboxyl group of the flux is below 0.5850, the reaction products of the resin component and the flux are less susceptible to nucleophilic attack, thus suppressing porosity. If the maximum Mulliken charge of the carbon atom in the carboxyl group of the flux is below 0.5850, the attraction of unreacted flux by the reaction products of the resin component and the flux is suppressed. The polarization of the ester bond in the reaction products decreases, thus weakening the attraction of unreacted flux (anions). Furthermore, in fluxes with a maximum Mulliken charge of the carbon atom in the carboxyl group below 0.5850, the amount of protons released as hydrolysis catalysts is low. In fluxes with a small positive Mulliken charge on the carbon atom of the carboxyl group, the negative Mulliken charge of the oxygen atom on the side adjacent to the hydrogen atom is small. In this case, the polarization with the hydrogen atom is small, resulting in less proton release. Therefore, by using fluxes with a maximum Mulliken charge of carboxyl carbon of 0.5850 or less, porosity formation can be suppressed.

[0021] Furthermore, the conductive resin composition of the present invention comprises acid-treated solder particles. That is, the solder particles are pre-treated with acid before being incorporated into the resin components and flux. This removes most of the oxide coating on the surface of the solder particles. Moreover, when such solder particles are incorporated together with flux, the flux further removes the oxide coating from the solder particles. Since most of the oxide coating has been removed beforehand, the amount of water generated during oxide coating removal can be reduced. As a result, the formation of porosity caused by water generation can be suppressed.

[0022] The bonding sheet of the present invention comprises the conductive resin composition of the present invention. Therefore, it is possible to suppress the formation of pores.

[0023] The method for manufacturing the conductive resin composition of the present invention includes a first step of acid treating solder particles with an acid treating agent. That is, the conductive resin composition comprises acid-treated solder particles. Therefore, according to this method, a conductive resin composition capable of suppressing the formation of porosity can be manufactured.

[0024] Furthermore, the maximum value of the Mulliken charge on the carbon group of the flux is 0.5850 or less. Therefore, according to this method, it is possible to manufacture a conductive resin composition that can suppress the formation of porosity.

[0025] The method for manufacturing the bonding body of the present invention is based on the conductive resin composition of the present invention. Therefore, it is possible to suppress the formation of pores.

[0026] The joint of the present invention has an adhesive layer that serves as the cured product of the joint sheet of the present invention. Therefore, the formation of pores can be suppressed. Attached Figure Description

[0027] [ Figure 1 ] Figure 1 A and Figure 1 B illustrates one embodiment of a method for manufacturing a bonding piece; Figure 1 A shows the preparatory steps for peeling off the liner; Figure 1 B illustrates the configuration process of arranging the bonding piece on one face in the thickness direction of the peeling liner.

[0028] [ Figure 2 ] Figure 2 A~ Figure 2 E illustrates one embodiment of a method for using the bonding piece (a method for manufacturing the bonding body); Figure 2 A shows the third step of preparing two substrates having multiple electrodes arranged in a planar direction; Figure 2 B shows the fourth step of preparing the bonding sheet by coating a conductive resin composition. Figure 2C shows the fifth step of manufacturing a laminate by stacking the first substrate and the second substrate with bonding tabs sandwiched between the electrodes of the two substrates in a manner that the electrodes of the two substrates are facing each other. Figure 2 D shows the process of thermally pressing the first substrate and the second substrate with the bonding sheet in the sixth process; Figure 2 E illustrates the process in step 6 of forming an adhesive layer that solders the first substrate and the second substrate to the bonding sheet.

[0029] [ Figure 3 ] Figure 3 A graph showing the results of removing the oxide coating from the surface of solder particles using an acid treatment agent.

[0030] [ Figure 4 ] Figure 4 An explanatory diagram illustrating the observation points in the observation of solder accumulation and the evaluation of porosity formation. Detailed Implementation

[0031] 1. Conductive resin composition The conductive resin composition comprises acid-treated solder particles, resin components, and flux.

[0032] <Acid-treated solder particles> Acid-treated solder particles can be obtained by acid-treating solder particles using an acid treatment agent.

[0033] [Acid Treatment Agent] Acid treatment agents are components used to remove the oxide coating on the surface of solder particles.

[0034] The acid treatment agent has a carboxyl group. Examples of such acid treatment agents include carboxylic acid treatment agents. Examples of carboxylic acid treatment agents include monocarboxylic acid treatment agents, dicarboxylic acid treatment agents, and carboxylic acid treatment agents with three or more functions.

[0035] Examples of monocarboxylic acid treatment agents include, for example, aliphatic monocarboxylic acid treatment agents and aromatic monocarboxylic acid treatment agents.

[0036] Examples of aliphatic monocarboxylic acid treatment agents include acetic acid (0.5554), propionic acid (0.5755), and butyric acid (0.5738).

[0037] Examples of aromatic monocarboxylic acid treatment agents include benzoic acid (0.5364), 2-phenoxybenzoic acid (0.5413), and diphenylacetic acid (0.5930).

[0038] Examples of dicarboxylic acid treatment agents include aliphatic dicarboxylic acid treatment agents and aromatic dicarboxylic acid treatment agents.

[0039] Examples of aliphatic dicarboxylic acid treatment agents include glutaric acid (0.5761), pimelic acid (0.5789), adipic acid (0.5785), 3,3-dimethylglutaric acid (0.5807), 2-methyl adipic acid (0.5827), malonic acid (0.5864), succinic acid (0.5963), malic acid (0.6092), octanoic acid (0.5790), sebacic acid (0.5769), methylmalonic acid (0.5979), ethylmalonic acid (0.6062), and phenylmalonic acid (0.6119).

[0040] Examples of aromatic dicarboxylic acid treatment agents include phthalic acid (0.5245).

[0041] Examples of carboxylic acid treatment agents with three or more functions include aliphatic carboxylic acid treatment agents with three or more functions and aromatic carboxylic acid treatment agents with three or more functions.

[0042] Examples of aliphatic carboxylic acid treatment agents with three or more functions include citric acid (0.5930).

[0043] Examples of aromatic carboxylic acid treatment agents with three or more functions include trimellitic acid (0.5496) and pyromellitic acid (0.5357).

[0044] As an acid treatment agent, dicarboxylic acid treatment agents are preferred. As an acid treatment agent, aliphatic dicarboxylic acid treatment agents are more preferred. As an acid treatment agent, malic acid is even more preferred.

[0045] It should be noted that in the acid treatment agent, the value in parentheses represents the maximum value of the Mulliken charge, which will be discussed later.

[0046] The maximum value of the Mulliken charge of the acid treatment agent (described later) is, for example, 0.5700 or more. From the viewpoint of accelerating the removal of the oxide coating on the surface of the solder particles, it is preferable to exceed 0.5850, more preferably 0.5900 or more, and even more preferably 0.6000 or more. In addition, it is, for example, 0.6200 or less.

[0047] Acid treatment agents can be used alone or in combination of two or more.

[0048] [Solder particles] From an environmental adaptation perspective, solder materials that form solder particles can be categorized as lead-free solder materials. Specifically, examples of solder materials include tin and tin alloys. Examples of tin alloys include tin-bismuth alloys (Sn-Bi), tin-silver-copper alloys (Sn-Ag-Cu), and tin-silver alloys (Sn-Ag). Tin-bismuth alloys (Sn-Bi) and tin-silver-copper alloys (Sn-Ag-Cu) are preferred solder materials.

[0049] The tin content in the tin-silver-copper alloy is, for example, 90% by mass or more, preferably 95% by mass or more. Furthermore, the silver content in the tin-silver-copper alloy is, for example, 10% by mass or less, preferably 5% by mass or less. Additionally, the copper content in the tin-silver-copper alloy is, for example, 1% by mass or less, preferably 0.5% by mass or less.

[0050] For example, the tin content in the tin-bismuth alloy is, for example, 80% by mass or less, preferably 50% by mass or less. Furthermore, the bismuth content in the tin-bismuth alloy is, for example, 20% by mass or more, preferably 50% by mass or more.

[0051] The melting point of the solder material (i.e., the melting point of the solder particles) is higher than the softening point of the solid resin described later, for example, 100°C to 260°C, preferably 135°C to 235°C, and more preferably 185°C to 220°C. It should be noted that the melting point can be determined by differential scanning calorimetry (DSC) (as follows).

[0052] The shape of the solder particles is not particularly limited; for example, spherical, plate-shaped, and needle-shaped particles can be included. Preferably, spherical particles can be included.

[0053] From the viewpoint of miniaturization and low particle size reduction, the average primary particle size of the solder particles is, for example, 10 μm or less, preferably 7 μm or less, more preferably 5 μm or less, and also, for example, 0.1 μm or more, preferably 0.5 μm or more. It should be noted that the average primary particle size can be measured using a laser diffraction particle size distribution measuring device.

[0054] Solder particles can be used alone or in combination of two or more types.

[0055] [Manufacturing of acid-treated solder particles] Acid-treated solder particles can be obtained by acid-treating solder particles using an acid-treating agent. Specifically, the method for manufacturing acid-treated solder particles includes: a preparation step of preparing an aqueous solution of the acid-treating agent; an immersion step of immersing solder particles in the aqueous solution of the acid-treating agent; a cleaning step of cleaning the solder particles; and a solvent removal step of removing the solvent.

[0056] (Preparation process) In the preparation process, an aqueous solution of the acid treatment agent is prepared. To prepare the aqueous solution of the acid treatment agent, the acid treatment agent is diluted with water, thereby preparing the aqueous solution of the acid treatment agent.

[0057] The molar concentration of the aqueous solution of the acid treatment agent is, for example, 0.5 mol / L to 3.0 mol / L.

[0058] (Immersion process) In the immersion process, solder particles are immersed in an aqueous solution of acid treatment agent at room temperature (10℃~30℃) and stirred as needed.

[0059] The soaking time is, for example, 1 minute to 60 minutes, preferably 5 minutes to 30 minutes.

[0060] (Cleaning process) The cleaning process involves removing solder particles. Specifically, after the solder particles have settled naturally, the supernatant is removed, a solvent (e.g., ethanol, acetone) is added, and the mixture is stirred. It should be noted that the cleaning process can be repeated multiple times.

[0061] (Solvent removal process) In the solvent removal process, the solvent is removed. To remove the solvent, vacuum drying is performed, for example, in a vacuum oven.

[0062] In vacuum drying, the drying temperature is, for example, 20°C to 50°C. The drying time is, for example, 0.5 hours to 12 hours, preferably 1 hour to 6 hours.

[0063] Therefore, acid treatment agents are used to acid-treat solder particles to produce acid-treated solder particles.

[0064] Regarding the solder particles, acid treatment removes most of the oxide coating on the surface of the solder particles. Specifically, the thickness of the oxide coating is, for example, 5 nm or less, preferably 3 nm or less, more preferably 1 nm or less, even more preferably 0.5 nm or less, and typically 0.1 nm or more.

[0065] If the thickness of the oxide coating is below the above-mentioned upper limit, the generation of pores caused by the removal of the oxide coating as described later can be suppressed.

[0066] It should be noted that the thickness of the oxide coating can be measured using a transmission electron microscope (TEM).

[0067] In addition, during the manufacture of acid-treated solder particles, some or all of the resin components described later can be pre-mixed. In this case, some or all of the resin components are mixed in after the cleaning process and before the solvent removal process.

[0068] The proportion of acid-treated solder particles relative to the conductive resin composition is, for example, 40% to 70% by mass, preferably 50% to 65% by mass, and more preferably 55% to 60% by mass.

[0069] <Resin Composition> There are no particular restrictions on the resin composition, but it is preferable to include both solid and liquid resins. If the resin composition includes both solid and liquid resins, the moldability and adhesion of the bonding sheet (described later) will be excellent.

[0070] The mass ratio of solid resin to liquid resin in the resin composition is, for example, 0.5 to 1.5, preferably 0.7 to 1.3, and more preferably 0.9 to 1.1.

[0071] It should be noted that solid resins are non-flowing and non-viscous at 25°C. Liquid resins, on the other hand, are liquids and fluids that exhibit viscosity at 25°C.

[0072] Thermoplastic resins and curable resins are selected as solid and liquid resins.

[0073] [Thermoplastic resin] Examples of thermoplastic resins include thermoplastic epoxy resins, thermoplastic phenolic resins, phenoxy resins, polyolefins (e.g., polyethylene, polypropylene, ethylene-propylene copolymers, etc.), thermoplastic acrylic resins, thermoplastic polyesters, polyvinyl acetate, ethylene-vinyl acetate copolymers, polyvinyl chloride, polystyrene, polyacrylonitrile, polyamide (nylon (registered trademark)), polycarbonate, polyacetal, polyethylene terephthalate, polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyallyl sulfone, thermoplastic polyimide, thermoplastic polyurethane, polyaminobismaleimide, polyamide imide, polyetherimide, bismaleimide triazine resin, polymethylpentene, fluoropolymers, liquid crystal polymers, olefin-vinyl alcohol copolymers, ionomers, polyarylates, acrylonitrile-ethylene-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, and butadiene-styrene copolymers.

[0074] Thermoplastic resins can be used alone or in combination with two or more.

[0075] The proportion of thermoplastic resin relative to 100 parts by weight of resin content is, for example, 50 parts by weight or less, preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and even more preferably 0 parts by weight. That is, the resin content is more preferably free of thermoplastic resin.

[0076] [Curing Resin] Examples of curable resins include thermosetting resins. Examples of thermosetting resins include thermosetting epoxy resins, urea resins, melamine resins, diallyl phthalate resins, silicone resins, phenolic resins, thermosetting acrylic resins, thermosetting polyesters, thermosetting polyimides, and thermosetting polyurethanes. Thermosetting epoxy resins and phenolic resins are preferred examples of curable resins.

[0077] Examples of thermosetting epoxy resins include thermosetting bisphenol type epoxy resins (e.g., thermosetting bisphenol A type epoxy resin, thermosetting bisphenol F type epoxy resin, and thermosetting bisphenol S type epoxy resin), thermosetting Novolac type epoxy resins (e.g., thermosetting phenol Novolac type epoxy resin, thermosetting cresol Novolac type epoxy resin, and thermosetting biphenyl type epoxy resin), thermosetting naphthalene type epoxy resin, thermosetting fluorene type epoxy resin (e.g., thermosetting bisarylfluorene type epoxy resin), and thermosetting triphenylmethane type epoxy resin (e.g., thermosetting trihydroxyphenylmethane type epoxy resin). Thermosetting bisphenol type epoxy resins are preferred as thermosetting epoxy resins. Thermosetting bisphenol A type epoxy resins are more preferred as thermosetting epoxy resins.

[0078] Examples of phenolic resins include Novolac-type phenolic resins and dicyclopentadiene-type phenolic resins. Examples of Novolac-type phenolic resins include phenol Novolac resins and cresol Novolac resins. Novolac-type phenolic resins are preferred. Phenol Novolac resins are more preferred.

[0079] In addition, the above-mentioned thermosetting resin can be in any form, either solid or liquid, at room temperature (25°C).

[0080] As a thermosetting resin, it is preferable to use both solid thermosetting resin and liquid thermosetting resin.

[0081] The curing temperature of the thermosetting resin is the same as or higher than the melting point of the solder particles, for example, 100°C to 260°C, preferably 135°C to 235°C, and more preferably 185°C to 220°C.

[0082] Curing resins can be used alone or in combination with two or more types.

[0083] The proportion of curable resin relative to 100 parts by weight of resin component is, for example, 50 parts by weight or more, preferably 80 parts by weight or more, more preferably 90 parts by weight or more, and even more preferably 100 parts by weight. That is, the resin component is more preferably formed from curable resin.

[0084] In addition, the resin components preferably include a thermosetting resin as a solid resin and a thermosetting resin as a liquid resin.

[0085] The thermosetting resin, as a solid resin, is contained in a proportion of, for example, 30 to 80 parts by mass, preferably 30 to 60 parts by mass, more preferably 30 to 50 parts by mass, and even more preferably 35 to 45 parts by mass.

[0086] In detail, regarding the content ratio of the thermosetting resin as a solid resin, from the viewpoint of suppressing the formation of pores caused by the removal of the oxide coating described later, it is, for example, 30 parts by mass or more, preferably 35 parts by mass or more. In addition, from the viewpoint of suppressing the formation of pores caused by the removal of the oxide coating described later, it is, for example, 80 parts by mass or less, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 45 parts by mass or less.

[0087] The proportion of the thermosetting resin as a liquid resin is, for example, 20 parts by weight to 70 parts by weight, preferably 40 parts by weight to 70 parts by weight, more preferably 50 parts by weight to 70 parts by weight, and even more preferably 55 parts by weight to 65 parts by weight.

[0088] In detail, regarding the content ratio of the thermosetting resin as a liquid resin, from the viewpoint of suppressing the formation of pores caused by the removal of the oxide coating described later, it is, for example, 20 parts by mass or more, preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more. In addition, from the viewpoint of suppressing the formation of pores caused by the removal of the oxide coating described later, it is, for example, 70 parts by mass or less, preferably 65 parts by mass or less.

[0089] Furthermore, the softening point of the solid resin is lower than the melting point of the solder particles. Specifically, in the hot pressing process described later, from the viewpoint of softening the solid resin without melting the solder particles, the softening point of the solid resin is lower than the melting point of the solder particles. The softening point of the solid resin is, for example, 40°C to 200°C, preferably 60°C to 150°C.

[0090] It should be noted that the softening point mentioned above can be determined by a thermomechanical analysis device.

[0091] Alternatively, the resin component can be formulated with a known solvent to prepare a varnish. The solid content concentration of the resin component in the varnish is, for example, 30% to 80% by mass, preferably 40% to 70% by mass.

[0092] In addition, the proportion of the resin component relative to the conductive resin composition is, for example, 20% to 60% by mass, preferably 30% to 50% by mass, and more preferably 33% to 45% by mass.

[0093] <Fluoride> Flux is a component used to further remove the oxide coating on the surface of acid-treated solder particles. Additionally, flux is a component that removes the oxide coating from the surfaces of metal electrodes (specifically, the first and second electrodes described later), enabling solder bonding.

[0094] Fluxes contain carboxyl groups. From the viewpoint of further removing the oxide coating on the surface of solder particles, carboxylic acids can be cited as examples of such fluxes. Examples of carboxylic acids include monocarboxylic acids, dicarboxylic acids, and carboxylic acids with three or more functions.

[0095] Examples of monocarboxylic acids include aliphatic monocarboxylic acids and aromatic monocarboxylic acids.

[0096] Examples of aliphatic monocarboxylic acids include acetic acid (0.5554), propionic acid (0.5755), and butyric acid (0.5738).

[0097] Examples of aromatic monocarboxylic acids include benzoic acid (0.5364) and 2-phenoxybenzoic acid (0.5413).

[0098] Examples of dicarboxylic acids include, for instance, aliphatic dicarboxylic acids.

[0099] Examples of aliphatic dicarboxylic acids include glutaric acid (0.5761), pimelic acid (0.5789), adipic acid (0.5785), 3,3-dimethylglutaric acid (0.5807), and 2-methyladipic acid (0.5827).

[0100] Examples of carboxylic acids with three or more functions include aromatic carboxylic acids with three or more functions.

[0101] Examples of aromatic carboxylic acids with three or more functions include trimellitic acid (0.5496) and pyromellitic acid (0.5357).

[0102] It should be noted that the values ​​in parentheses in the flux description represent the maximum value of the Mulliken charge, which will be discussed later.

[0103] In addition, the salts of the aforementioned carboxylic acids can also be used as fluxes.

[0104] From the viewpoint of further removing the oxide coating on the surface of solder particles, dicarboxylic acids are preferred as fluxes. Aliphatic dicarboxylic acids are more preferred as fluxes. Glutaric acid, pimelic acid, adipic acid, and 3,3-dimethylglutaric acid are further preferred as fluxes. From the viewpoint of improving solder accumulation (described later), glutaric acid is particularly preferred as a flux.

[0105] In addition, the maximum value of the Mulliken charge of the carbon group of the flux is 0.5850 or less, preferably 0.5800 or less, more preferably 0.5790 or less, even more preferably 0.5770 or less, and usually 0.5000 or more.

[0106] The maximum value of the Mulliken charge on the carbon atom of the carboxyl group in the flux is an indicator of the positive charge of the carbon atom. A smaller value indicates a lower positive charge and a tendency for decreased reactivity based on anionic nucleophilic attack, as detailed later. As a result, the decomposition of the reaction products between the resin components and the flux (described later) can be suppressed, thus inhibiting the formation of pores.

[0107] On the other hand, if the maximum value of the Mulliken charge exceeds the upper limit, the decomposition of the reaction products of the resin components and flux described later cannot be suppressed, and the formation of pores cannot be suppressed.

[0108] It should be noted that the so-called Mulliken charge is obtained by calculating the average distribution of electrons based on the electronic states, and thereby calculating the charge distribution in each atom. Mulliken charge can be calculated, for example, using the general-purpose quantum chemistry calculation program Gaussian16 (Gaussian Corporation). Regarding the Mulliken charge, it can be calculated individually for each atom within the molecule, taking a positive or negative value. A positive or negative Mulliken charge value indicates whether the atom has a positive or negative charge. In detail, the method for calculating the maximum value of the Mulliken charge will be described in the examples described later.

[0109] Furthermore, it is preferable to adjust the flux so that the maximum value of the Mulliken charge in the acid treatment agent is greater than the maximum value of the Mulliken charge in the flux. Specifically, the adjustment is made such that the maximum value of the Mulliken charge in the acid treatment agent exceeds 0.5850, while on the other hand, the maximum value of the Mulliken charge in the flux is less than 0.5850.

[0110] More specifically, the ratio of the maximum value of Mulliken charge in the acid treatment agent to the maximum value of Mulliken charge in the flux (maximum value of Mulliken charge in the acid treatment agent / maximum value of Mulliken charge in the flux) is adjusted in such a way as to be greater than 1.00, preferably greater than 1.02, more preferably greater than 1.04, further preferably greater than 1.05, and for example less than 1.50.

[0111] Therefore, it is possible to accelerate the removal of the oxide coating on the surface of solder particles using acid treatment agents, and to suppress the formation of pores (the formation of pores caused by the decomposition of the reaction products of the resin components and flux, as described later).

[0112] Fluxes can be used alone or in combination with two or more types.

[0113] Alternatively, the flux can be formulated with a known solvent (e.g., ethanol) to prepare a flux solution. The solid content concentration of the flux solution is, for example, 10% to 50% by mass, preferably 20% to 40% by mass.

[0114] The flux content is, for example, 0.5 to 10 parts by mass relative to 100 parts by mass of acid-treated solder particles, preferably 1 to 10 parts by mass, and more preferably 5 to 7 parts by mass.

[0115] In detail, from the viewpoint of further removing the oxide coating on the surface of solder particles, the flux content is, for example, 0.5 parts by mass or more, preferably 1 part by mass or more, more preferably 5 parts by mass or more, relative to 100 parts by mass of acid-treated solder particles. In addition, for example, it is 10 parts by mass or less. From the viewpoint of suppressing the formation of pores caused by the removal of the oxide coating of solder particles as described later, it is preferably 7 parts by mass or less.

[0116] In addition, the flux content relative to the conductive resin composition is, for example, 0.5% to 10% by mass, preferably 1% to 10% by mass, and more preferably 3% to 5% by mass.

[0117] <Additives> The conductive resin composition may contain additives (e.g., curing agents, curing accelerators, and silane coupling agents) in appropriate proportions as needed.

[0118] 2. Preparation of conductive resin composition A method for manufacturing a conductive resin composition includes: a first step of acid treating solder particles using an acid treatment agent; and a second step of mixing the acid-treated solder particles, a resin component, and a flux.

[0119] <Step 1> In the first step, the solder particles are acid-treated using an acid treatment agent to produce acid-treated solder particles. Specifically, acid-treated solder particles are manufactured according to the above-described method for manufacturing acid-treated solder particles.

[0120] <Second Process> In the second step, acid-treated solder particles, resin components, and flux are mixed. Specifically, the acid-treated solder particles, resin components, flux, and additives as needed are mixed and stirred as required. This produces a conductive resin composition.

[0121] Alternatively, the conductive resin composition can be formulated with a known solvent to prepare a varnish. The solid content concentration of the varnish of the conductive resin composition is, for example, 50% to 80% by mass, preferably 60% to 75% by mass.

[0122] Next, the bonding sheet obtained using this conductive resin composition will be described in detail.

[0123] 3. Joining plate The bonding sheet is formed from a conductive resin composition into a sheet shape. That is, the bonding sheet contains a conductive resin composition.

[0124] Reference Figure 1 A and Figure 1 B details one embodiment of the manufacturing method of the bonding piece.

[0125] exist Figure 1 A and Figure 1 In diagram B, the vertical direction on the paper surface is the vertical direction (thickness direction). Additionally, the upper side of the paper surface is the upper side (one side of the thickness direction), and the lower side of the paper surface is the lower side (the other side of the thickness direction). Furthermore, the horizontal and depth directions of the paper surface are surface directions orthogonal to the vertical direction. Specifically, this is based on the directional arrows in each diagram.

[0126] The method for manufacturing the bonding piece includes: a preparation step for preparing a release liner 10; and a configuration step for configuring the bonding piece 1 on one surface of the release liner 10 in the thickness direction.

[0127] [Preparation Process] In the preparation process, such as Figure 1 As shown in Figure A, prepare to peel off the liner 10.

[0128] The release liner is a support for supporting the bonding piece 1. The release liner 10 has a film shape.

[0129] The release liner 10 is, for example, a plastic substrate (plastic film). Examples of plastic substrates include polyester sheets (polyethylene terephthalate (PET) sheets), polyolefin sheets (e.g., polyethylene sheets, polypropylene sheets), polyvinyl chloride sheets, polyimide sheets, and polyamide sheets (nylon sheets). Surface treatments such as silicone treatment may also be applied to the surface (one side in the thickness direction) of the release liner 10.

[0130] For example, the thickness of the peeling liner 10 is, for example, 1 μm to 100 μm.

[0131] [Configuration Process] In the configuration process, such as Figure 1 As shown in Figure B, a bonding piece 1 is disposed on one face of the peeling liner 10 in the thickness direction.

[0132] In order to arrange the bonding piece 1 on one side of the release liner 10 in the thickness direction, a conductive resin composition (varnish of the conductive resin composition) is applied to one side of the release liner 10 in the thickness direction, and then dried as needed.

[0133] As for drying conditions, the drying temperature is, for example, 40°C or higher to 100°C. The drying time is, for example, 1 minute to 60 minutes.

[0134] Using the above operations, a bonding piece 1 can be manufactured that is disposed on one side of the release liner 10 in the thickness direction. In addition, solder particles 5 are dispersed in the resin component of the bonding piece 1.

[0135] From the viewpoint of miniaturization and low height, the thickness of the bonding piece 1 is, for example, 50 μm or less, preferably 25 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, and, for example, 1 μm or more.

[0136] Next, the method of using the bonding piece 1 (the method of manufacturing the bonding body) will be described in detail.

[0137] 4. How to use the bonding plate (manufacturing method of the bonding body) One embodiment of the method of using the bonding piece (method of manufacturing the bonding body) is described below. Figure 2 A~ Figure 2 E will be explained in detail.

[0138] The method of using the bonding sheet (method of manufacturing the bonding body) includes: a third step, preparing multiple substrates having multiple electrodes arranged in a planar direction; a fourth step, coating a conductive resin composition to prepare the bonding sheet 1; a fifth step, stacking the two substrates with the bonding sheet 1 sandwiched between the electrodes of the two substrates to manufacture a laminate 6; and a sixth step, heating the laminate 6 to melt the solder particles 5, thereby forming a columnar solder portion 15 in a manner that electrically connects the electrodes of the two substrates, and curing the resin composition.

[0139] [Step 3] In the third step, multiple substrates having multiple electrodes arranged in a planar direction are prepared. This method will be described in detail for the case where two substrates having multiple electrodes arranged in a planar direction are prepared. Specifically, as follows... Figure 2 As shown in Figure A, prepare the first substrate 2 and the second substrate 4.

[0140] The first substrate 2 has a flat plate shape.

[0141] The first substrate 2 includes a first wiring circuit board 11 and a plurality of first electrodes 12 arranged in the surface direction of the first wiring circuit board 11. In other words, the first substrate 2 includes a first wiring circuit board 11 and a plurality of first electrodes 12 disposed on the surface (one surface in the thickness direction) of the first wiring circuit board 11.

[0142] The first wiring circuit board 11 is formed, for example, from insulating material and semiconductor material.

[0143] The thickness of the first wiring circuit board 11 is, for example, 5 μm to 1000 μm.

[0144] The first electrode 12 is formed from metal.

[0145] The first electrode 12 is configured as a dot pattern in the first substrate 2, for example.

[0146] In detail, the first electrode 12 has a circular shape when viewed from above. In addition, a plurality of first electrodes 12 are arranged equally in the planar direction.

[0147] The thickness of the first electrode 12 is, for example, 0 μm to 20 μm, preferably 0.001 μm to 5 μm. It should be noted that when the surface of the first substrate 2 is consistent with the surface of the first electrode 12, the thickness of the first electrode 12 is 0 μm.

[0148] The diameter of the first electrode 12 is, for example, 1 μm to 200 μm, preferably 1 μm to 100 μm, more preferably 1 μm to 50 μm, and even more preferably 1 μm to 20 μm.

[0149] In addition, in the planar direction, the distance (spacing) between adjacent first electrodes 12 is, for example, 3 μm to 400 μm, preferably 5 μm to 200 μm, more preferably 7 μm to 100 μm, and even more preferably 10 μm to 40 μm.

[0150] The second substrate 4 has a flat plate shape.

[0151] The second substrate 4 includes: a second wiring circuit board 13; and a plurality of second electrodes 14 arranged in the surface direction of the second wiring circuit board 13. In other words, the second substrate 4 includes: a second wiring circuit board 13; and a plurality of second electrodes 14 disposed on the surface (the other side in the thickness direction) of the second wiring circuit board 13.

[0152] The second wiring circuit board 13 is formed, for example, from an insulating material or a semiconductor material.

[0153] The thickness of the second wiring circuit board 13 is, for example, 5 μm to 1000 μm.

[0154] The second electrode 14 is formed from metal.

[0155] The second electrode 14 is configured as a dot pattern in the second substrate 4, for example.

[0156] In detail, the second electrode 14 has a circular shape when viewed from above. In addition, a plurality of second electrodes 14 are arranged equally in the planar direction.

[0157] The thickness of the second electrode 14 is, for example, 0 μm to 20 μm, preferably 0.001 μm to 5 μm. It should be noted that when the surface of the second substrate 4 is consistent with the surface of the second electrode 14, the thickness of the second electrode 14 is 0 μm.

[0158] The diameter of the second electrode 14 is, for example, 1 μm to 2100 μm, preferably 1 μm to 100 μm, more preferably 1 μm to 50 μm, and even more preferably 1 μm to 20 μm.

[0159] Furthermore, in the planar direction, the distance (spacing) between adjacent second electrodes 14 is the same as the distance (spacing) between adjacent first electrodes 12 in the planar direction as described above.

[0160] [Step 4] In the fourth process, such as Figure 2 As shown in B, the bonding piece 1 is prepared. Specifically, the bonding piece 1 is prepared according to the bonding piece manufacturing method described above.

[0161] [Step 5] In the fifth process, such as Figure 2 As shown in Figure C, two substrates are stacked with bonding sheet 1 sandwiched between the electrodes of the two substrates to form a laminate 6. Specifically, the first electrode 12 of the first substrate 2 and the second electrode 14 of the second substrate 4 are sandwiched between bonding sheet 1 to form a laminate 6.

[0162] In detail, firstly, the first substrate 2 and the second substrate 4 are brought close to the bonding sheet 1, so that the first substrate 2 and the second substrate 4 are in contact with the bonding sheet 1. More specifically, in the thickness direction, with the first electrode 12 and the second electrode 14 facing each other, one surface of the first substrate 2 in the thickness direction is in contact with another surface of the bonding sheet 1 in the thickness direction, and another surface of the second substrate 4 in the thickness direction is in contact with one surface of the bonding sheet 1 in the thickness direction.

[0163] Thus, a laminate 6 is manufactured.

[0164] [Step 6] In the sixth step, the laminate 6 is heated to melt the solder particles 5, thereby forming a columnar solder section 15 in a manner that electrically connects the electrodes of the two substrates, and the resin components are cured.

[0165] Specifically, firstly, such as Figure 2 As shown in D, the first substrate 2 and the second substrate 4 are thermally pressed together with the bonding piece 1.

[0166] Specifically, while heating the laminate 6, the first substrate 2 and the second substrate 4 are pressed toward the bonding piece 1 (thermal pressing).

[0167] The hot-pressing temperature is above the softening point of the thermoplastic resin and below the melting point of the solder particles 5. That is, in this process, the thermoplastic resin is softened without melting the solder particles. Specifically, the hot-pressing temperature is, for example, below 180°C, preferably below 100°C, more preferably below 80°C, and also, for example, above 40°C. Furthermore, the hot-pressing pressure is, for example, 0.001 MPa to 10 MPa, preferably 0.005 MPa to 5 MPa, and more preferably 0.01 MPa to 1 MPa.

[0168] As a result, the resin components soften, the first electrode 12 of the first substrate 2 is embedded in the bonding sheet 1, and one side of the first substrate 2 in the thickness direction contacts the bonding sheet 1. In addition, the second electrode 14 of the second substrate 4 is embedded in the bonding sheet 1, and the other side of the second substrate 4 in the thickness direction contacts the bonding sheet 1.

[0169] Next, as Figure 2 As shown in E, the laminate 6 is heated. Preferably, the laminate 6 is heated in a pressure oven 25. The pressure oven 25 refers to a device that can heat and pressurize simultaneously in a closed space, such as an automatic heating and pressurizing treatment device, a pressure oven, a non-porous pressure oven, an autoclave, or a vacuum pressure reflow oven.

[0170] When the laminate 6 is heated, volatiles may sometimes evaporate due to the heating. Such volatiles can sometimes interfere with electrical connections in the laminate 6. On the other hand, when the laminate 6 is heated using a pressure oven 25, the generation of the aforementioned volatiles can be suppressed by applying pressure. As a result, the aforementioned interference can be suppressed.

[0171] The heating temperature is a temperature above the melting point of the solder particles 5. Specifically, the heating temperature is, for example, 100°C or higher, preferably 130°C or higher, more preferably 200°C or higher, and, for example, 300°C or lower, preferably 280°C or lower, more preferably 270°C or lower.

[0172] Through this heating, the solder particles 5 melt. The molten solder particles 5 aggregate between the first electrode 12 and the second electrode 14, which are opposed in the thickness direction (self-aggregation), forming a columnar solder portion 15 in a manner that electrically connects the first electrode 12 and the second electrode 14. On the other hand, the resin component in the bonding sheet 1 is driven out by the self-aggregated solder particles 5 and moves towards the periphery of the columnar solder portion 15. Subsequently, the thermosetting resin in the resin component is thermosetting, becoming a cured resin 16 that bonds the first substrate 2 and the second substrate 4.

[0173] Thus, an adhesive layer 3 comprising columnar solder portions 15 and cured resin 16 is formed from the bonding sheet 1 between the two substrates (the first substrate 2 and the second substrate 4). In other words, the adhesive layer 3 is a cured product of the bonding sheet 1 (conductive resin composition).

[0174] From the viewpoint of miniaturization and low height, the thickness of the adhesive layer 3 is less than 50 μm, preferably less than 25 μm, more preferably less than 15 μm, even more preferably less than 5 μm, and for example, more than 1 μm.

[0175] Thus, the joint 20 is manufactured.

[0176] The joint 20 includes: a first substrate 2; a second substrate 4 disposed at intervals in the thickness direction (the thickness direction orthogonal to the surface direction); and an adhesive layer 3 sandwiched between the first substrate 2 and the second substrate 4. In other words, the joint 20 sequentially includes the first substrate 2, the adhesive layer 3, and the second substrate 4 on the side facing the thickness direction. More specifically, the joint 20 includes: a first substrate 2; an adhesive layer 3 directly disposed on the upper surface (one surface in the thickness direction) of the first substrate 2; and a second substrate 4 directly disposed on the upper surface (one surface in the thickness direction) of the adhesive layer 3.

[0177] The adhesive layer 3 bonds the first substrate 2 to the second substrate 4. Specifically, the adhesive layer 3 is bonded to other surfaces of the first substrate 2, excluding the first electrode 12. In addition, the adhesive layer 3 is bonded to other surfaces of the second substrate 4, excluding the second electrode 14.

[0178] Furthermore, the adhesive layer 3 (specifically, the columnar solder portion 15 in the adhesive layer 3) electrically connects the first electrode 12 and the second electrode 14, which are opposed in the thickness direction. In addition, the columnar solder portion 15 has a columnar shape (specifically, a cylindrical shape), is disposed between the first electrode 12 and the second electrode 14, and is in contact with them.

[0179] <Effects> The conductive resin composition contains acid-treated solder particles 5. Therefore, it is able to suppress the formation of pores.

[0180] In detail, from the viewpoint of promoting the self-aggregation of the molten solder particles 5 in the above-mentioned sixth process, the removal of the oxide coating on the surface of the solder particles 5 was studied.

[0181] On the other hand, if the solder particles 5 are combined with flux to remove the oxide coating on the surface of the solder particles 5, water is generated when the flux removes the oxide coating on the surface of the solder particles 5. Moreover, this water evaporates due to heating in the fifth and sixth steps described above, resulting in the formation of pores (in other words, pores are generated due to the removal of the oxide coating).

[0182] In contrast, the conductive resin composition includes acid-treated solder particles 5. That is, the solder particles 5 are pre-treated with acid before being incorporated into the resin components and flux. This removes most of the oxide coating on the surface of the solder particles 5. Furthermore, if such solder particles 5 are incorporated with flux, the oxide coating on the solder particles 5 is further removed by the flux, but since most of the oxide coating has been removed beforehand, the amount of water generated during oxide coating removal is reduced. As a result, the formation of porosity caused by oxide coating removal can be suppressed.

[0183] Furthermore, in this conductive resin composition, the maximum value of the Mulliken charge on the carbon of the carboxyl group in the flux is 0.5850 or less. Therefore, the formation of pores can be suppressed.

[0184] Specifically, in conductive resin compositions, there are cases where the resin component reacts with the flux (e.g., ester formation reaction). However, if the reaction product of the resin component and flux (e.g., ester bond) is nucleophilically attacked by unreacted flux (anion), decomposition occurs, generating gas. This gas can lead to the undesirable situation of porosity. The ease with which this nucleophilic attack occurs depends on the force by which the reaction product of the resin component and flux attracts the unreacted flux and the amount of protons released from the unreacted flux.

[0185] If the maximum Mulliken charge of the carbon atom in the carboxyl group of the flux is below 0.5850, the reaction products of the resin component and the flux become less susceptible to nucleophilic attack, thus suppressing porosity. If the maximum Mulliken charge of the carbon atom in the carboxyl group of the flux is below 0.5850, the attraction of unreacted flux by the reaction products of the resin component and the flux is suppressed. The polarization of the ester bond in the reaction products decreases, thus weakening the attraction of unreacted flux (anions). Furthermore, in fluxes with a maximum Mulliken charge of the carbon atom in the carboxyl group below 0.5850, the amount of protons released as hydrolysis catalysts is low. In fluxes with a small positive Mulliken charge on the carbon atom of the carboxyl group, the negative Mulliken charge of the oxygen atom on the side adjacent to the hydrogen atom is small. In this case, the polarization with the hydrogen atom is small, resulting in less proton release. Therefore, by using fluxes with a maximum Mulliken charge of carboxyl carbon of 0.5850 or less, porosity formation can be suppressed.

[0186] Based on the above, in terms of the conductive resin composition, by using acid-treated solder particles 5 and a specified flux, it is possible to suppress the formation of pores.

[0187] The bonding sheet 1 contains a conductive resin composition. Therefore, it is able to suppress the formation of pores.

[0188] The method for manufacturing the conductive resin composition includes a first step of acid treating the solder particles 5 with an acid treating agent. That is, the conductive resin composition comprises the acid-treated solder particles 5. Therefore, according to this method, a conductive resin composition capable of suppressing the formation of porosity can be manufactured.

[0189] Furthermore, the maximum value of the Mulliken charge on the carbon group of the flux is 0.5850 or less. Therefore, according to this method, it is possible to manufacture a conductive resin composition that can suppress the formation of porosity.

[0190] The bonding body is manufactured using the aforementioned conductive resin composition. Therefore, the formation of pores can be suppressed.

[0191] The joint 20 has an adhesive layer 3 that serves as a cured product of the joint piece 1. Therefore, it is possible to suppress the formation of pores.

[0192] <Variation Example> In the modified examples, the same reference numerals are used to mark the same components and processes as in the first embodiment, and detailed descriptions are omitted. Furthermore, unless otherwise specified, the modified examples can achieve the same effects as the first embodiment. Moreover, the first embodiment and the modified examples can be appropriately combined.

[0193] In addition, in the above description, the first electrode 12 and the second electrode 14 are configured as a dot pattern, but the configuration of the first electrode 12 and the second electrode 14 is not limited to this.

[0194] In addition, in the above description, the first electrode 12 and the second electrode 14 have a circular shape when viewed from above, but the shape of the first electrode 12 and the second electrode 14 is not limited to this, for example, it can also be a four-cornered shape when viewed from above.

[0195] In addition, in the above description, the second substrate 4 has a flat shape, but the shape of the second substrate 4 is not limited to this. For example, it can also be the shape of a chip component (e.g., mini / microLED).

[0196] Example Next, the present invention will be described based on embodiments and comparative examples, but the present invention is not limited to the embodiments described below. It should be noted that unless otherwise specified, "parts" and "%" are mass standards. In addition, the specific values ​​of mixing ratios (including proportions), physical property values, parameters, etc. used in the following description can replace the corresponding upper limit values ​​(values ​​defined as "less than" or "less than") or lower limit values ​​(values ​​defined as "more than" or "exceeding") of the mixing ratios (including proportions), physical property values, parameters, etc., described in the "Specific Embodiments" above.

[0197] <Detailed information on ingredients> The trade names and abbreviations of the ingredients used in each embodiment and comparative example are described in detail.

[0198] Solder particles (1): Sn 96.5% by mass, Ag 3.0% by mass, Copper 0.5% by mass, Melting point 217~219℃, spherical, average primary particle size 3μm, trade name "SAC305 ST-3", manufactured by Mitsui Metals & Mining Co., Ltd. Solder particles (2): Sn 96.5% by mass, Ag 3.0% by mass, Copper 0.5% by mass, Melting point 217~219℃, spherical, average primary particle size 7μm, trade name "SAC305 ST-7", manufactured by Mitsui Metals & Mining Co., Ltd. Solder particles (3): Sn 96.5% by mass, Ag 3.0% by mass, copper 0.5% by mass, melting point 217-219℃, spherical, average primary particle size 8μm, trade name "SAC305 STC-7", manufactured by Mitsui Metals & Mining Co., Ltd. Solder particles (4): Sn42 mass%Bi58 mass%, melting point 138~140℃, spherical, average primary particle size 3μm, trade name "Sn42Bi58 ST-3", manufactured by Mitsui Metals & Mining Co., Ltd. Glutaric acid: Manufactured by Fujifilm and Wako Pure Chemical Industries, Ltd. Pimelic acid: manufactured by Tokyo Chemical Industry Co., Ltd. Adipic acid: Manufactured by Tokyo Chemical Industry Co., Ltd. 3,3-Dimethylglutaric acid: manufactured by Merck KCaA 2-Methyladipic acid: Manufactured by Fujifilm and Koko Pure Chemical Industries, Ltd. Malonic acid: Manufactured by Fujifilm and Wako Pure Chemical Industries, Ltd. Succinic acid: Manufactured by Fujifilm and Wako Pure Chemical Industries, Ltd. Malic acid: Manufactured by Tokyo Chemical Industry Co., Ltd. Benzylamine glutaric acid: manufactured by Showa Chemical Co., Ltd. YD-017: Bisphenol A type epoxy resin, epoxy equivalent 1650~2050, solid at 25℃, thermosetting resin, softening point 128℃, manufactured by Nippon Steel Chemical Co., Ltd. NPES907: Bisphenol A type epoxy resin, epoxy equivalent 1500-1600 g / eq, solid at 25°C, thermosetting resin, softening point 120-130°C, manufactured by Nan Ya Plastics Co., Ltd. J-DPP-115: Dicyclopentadiene-type phenolic resin, thermosetting resin, softening point 107℃~116℃, manufactured by JFE Chemical Co., Ltd. MEH-7851-H: Phenolic Novolac resin, thermosetting resin, softening point 64℃~85℃, manufactured by UBE Corporation. jER828: Bisphenol A type epoxy resin, epoxy equivalent 184-194 g / eq, liquid at 25°C, thermosetting resin, manufactured by Mitsubishi Chemical Corporation. <Manufacturing of Acid-Treated Solder Particles> Manufacturing Example 1 (Manufacturing of solder particles (1) treated with malic acid) [Preparation Process] Malic acid, used as an acid treatment agent, is dissolved in distilled water to a concentration of 1 mol / L. The dissolved gas is then replaced with nitrogen by nitrogen bubbling. This process yields an aqueous solution of the acid treatment agent.

[0199] [Immersion Process] Add 50g of an aqueous solution of acid treatment agent to 50g of solder particles (1), close the lid of the container and stir continuously for 20 minutes.

[0200] [Cleaning Process] Wait for the solder particles (1) to settle naturally, remove the supernatant, add ethanol, and stir until homogeneous. Then, repeat the same operation once.

[0201] Next, wait for the solder particles (1) to settle naturally, remove the supernatant, add acetone, and stir until homogeneous.

[0202] Next, wait for the solder particles (1) to settle naturally. After removing the supernatant, add jER828 according to the method recorded in Tables 1 to 3 and stir until it becomes uniform.

[0203] [Solvent Removal Process] Vacuum drying was performed in a vacuum oven at 25°C for 2 hours. Thus, acid-treated solder particles (malic acid-treated solder particles (1)) were produced.

[0204] Manufacturing Example 2 (Manufacturing of Solder Particles (1) Treated with Glutaric Acid) Based on the same steps as in Manufacturing Example 1, acid-treated solder particles (glutaric acid-treated solder particles (1)) were manufactured. In this case, the acid treatment agent was changed to glutaric acid.

[0205] Manufacturing Example 3 (Manufacturing of solder particles (2) treated with malic acid) Following the same steps as in Manufacturing Example 1, acid-treated solder particles (glutaric acid-treated solder particles) were manufactured. The solder particles were then changed to solder particles (2).

[0206] Manufacturing Example 4 Following the same steps as in Manufacturing Example 1, acid-treated solder particles (malic acid-treated solder particles) are manufactured. The solder particles are then replaced with solder particles (3).

[0207] Manufacturing Example 5 Following the same steps as in Manufacturing Example 1, acid-treated solder particles (malic acid-treated solder particles) are manufactured. The solder particles are then replaced with solder particles (4).

[0208] <Preparation of Conductive Resin Composition> Examples 1 to 24 and Comparative Examples 1 to 9 [Step 1] In the first step, the solder particles are acid-treated using an acid treatment agent. Specifically, the following are prepared: solder particles (1) treated with malic acid in Example 1, solder particles (1) treated with glutaric acid in Example 2, solder particles (2) treated with malic acid in Example 3, solder particles (3) treated with malic acid in Example 4, and solder particles (4) treated with malic acid in Example 5.

[0209] [Step 2] According to the formulations described in Tables 1 to 3, acid-treated solder particles, resin components, and flux are mixed. Then, acetone is added, and the mixture is stirred until homogeneous to produce a varnish of the conductive resin composition (70% by mass solids).

[0210] It should be noted that YD-017 was pre-dissolved in methyl ethyl ketone to prepare a varnish (60% by mass solids). Additionally, the flux was pre-dissolved in ethanol to prepare a flux solution (30% by mass solids). Furthermore, the values ​​for each component listed in Tables 1 to 3 refer to the solid content values.

[0211] <Preparation of the experimental joint> [Step 3] In Examples 1 to 14, Examples 16 to 24, and Comparative Examples 1 to 9, dummy wafers with Ni electrodes (size 10mm × 10mm, electrodes) were prepared as two substrates. 15μm (electrode spacing 15μm) and alkali-free glass (10mm × 10mm). Additionally, in Example 15, as two substrates, dummy wafers with Au electrodes (size 10mm × 10mm, electrode spacing 15μm) were prepared. 30μm (30μm electrode spacing) and alkali-free glass (10mm×10mm). Additionally, in Example 23, two dummy wafers with Au electrodes were prepared as two substrates (silicon wafer substrate, size 10mm×10mm, electrode spacing 30μm) and alkali-free glass (10mm×10mm). 30μm, electrode spacing 30μm). In Example 24, two FPC substrates (electrodes) were prepared as two substrates. 100μm, electrode spacing 200μm).

[0212] [Step 4] The conductive resin compositions of each embodiment and comparative example were applied to the release liner using an applicator and dried at 60°C for 5 minutes. This prepared a bonding sheet (5 μm thick).

[0213] [Step 5] A dummy wafer with Ni or Au electrodes, a bonding sheet, and alkali-free glass are sequentially bonded together at 50°C under vacuum. It should be noted that the release liner is removed during bonding. This process produces a laminate.

[0214] In addition, the obtained laminate was observed using an optical microscope (VHX-8000, KEYENCE) to confirm that no air bubbles were incorporated.

[0215] [Step 6] The laminate was placed in a vacuum pressure reflow oven (Model 1200 Table Top Furnace, SST International). After evacuation, it was pressurized with nitrogen to 4.5 atmospheres. Then, it was heated at a rate of 100°C / min, a maximum temperature of 260°C, and a holding time of 15 minutes. This produced a test joint.

[0216] <Evaluation> [Maximum value of Mulliken charge] For each flux, the maximum value of the Mulliken charge was calculated. Specifically, it was calculated using the general quantum chemistry calculation program Gaussian16 (Gaussian Corporation).

[0217] The initial structure was created and depicted using Avogadro (Avogadro Chemistry), a molecular editing software.

[0218] In a complex formed from two molecules, the initial structure is set in such a way that intermolecular interactions occur only between the carboxyl groups of the additional molecule and the flux.

[0219] In benzylamine glutaric acid (complex), two simulations were performed: the benzene ring-carboxyl interaction type and the primary amine-carboxyl interaction type, using the results of the low-energy structure.

[0220] When calculating with Gaussian16, the values ​​are obtained by structural optimization using B3LYP in the functional and 6-31+G(d) in the basis function system.

[0221] In this calculation, dispersion force correction is performed based on the D3 method of Grimme et al.

[0222] For the calculated Mulliken charge, the largest value was used in the case of molecules with multiple carboxyl groups. The results are shown in Tables 1 to 3.

[0223] [Removal rate of oxide coating on solder particle surface using acid treatment agent] Malic acid (acid treatment agent) was dissolved in distilled water and stirred to a concentration of 1 mol / L to prepare an aqueous solution of malic acid.

[0224] Next, 10g of solder particles (1) were immersed in 10g of an aqueous solution of malic acid and stirred.

[0225] After that, 1 cc of solution was taken after 1, 3, 5 and 10 minutes and the solder particles (1) and supernatant were separated by centrifugation (15000 rpm × 1 minute).

[0226] Next, the supernatant was filtered using a 0.45 μm syringe filter to obtain the filtrate. Then, approximately 100 mg of the filtrate was weighed into a container (hereinafter referred to as the sample collection volume), acid was added, and the container was sealed tightly.

[0227] Next, the sealed container was irradiated with microwaves (UltraWAVE, Milestone) to carry out pressurized acid decomposition at a maximum temperature of 250°C.

[0228] Then, ultrapure water was added to bring the volume to 50 mL, which was used as the assay solution. Furthermore, Sn ion concentration in the assay solution was determined by ICP-AES (SPS-3520UV, Hitachi High Technology) analysis (analysis wavelength 189.989 nm).

[0229] It should be noted that, in order to confirm the preparation of the test solution and the reproducibility of the test, sampling was carried out with n=2, and the average value was calculated.

[0230] In addition, the Sn ion concentration in the operating blank was separately determined. Specifically, for ultrapure water, Sn ion quantification was performed using the same procedure as described above. Thus, the Sn ion concentration in the operating blank was determined.

[0231] In addition, the Sn concentration was calculated according to the following formula. The results are shown in Table 4 and... Figure 3 It can be seen that the higher the Sn concentration, the faster the removal rate of the oxide coating on the surface of the solder particles (1) using the acid treatment agent. Furthermore, the Sn concentration was calculated using the same procedure when the acid treatment agent was changed to glutaric acid. The results are shown in Table 4 and... Figure 3 .

[0232] Sn ion concentration [mass%] = (Sn ion concentration in the test solution [ng / mL] - Sn ion concentration in the operational blank [ng / mL]) × volume of the test solution [mL] / (sample collection volume [mg] × 10000) according to Figure 3 It can be seen that, compared with glutaric acid, malic acid removes the oxidative coating faster.

[0233] [Observation of solder accumulation state] For the test joints of each embodiment and each comparative example, optical microscopy (VHX-8000, KEYENCE) was used for observation at 500x magnification, observing 7 locations within a 630μm × 500μm area (more specifically, Figure 4 (1) to (7) are shown. The solder buildup state is evaluated based on the following criteria. The results are shown in Tables 1 to 3.

[0234] {Benchmark} Level 4 (◎): Solder covers more than 95% of the electrode.

[0235] Level 3 (0): The solder covers the electrode at a ratio of more than 90% and less than 95%.

[0236] Level 2 (△): The solder covers the electrode at a ratio of more than 80% and less than 90%.

[0237] Level 1 (×): Solder is covered to a ratio of less than 80% relative to the electrode.

[0238] [Porosity formation] For the test joints of each embodiment and each comparative example, optical microscopy (VHX-8000, KEYENCE) was used for observation at a magnification of 500x, covering 7 locations within a range of 630μm × 500μm (more specifically, Figure 4 The formation of pores was observed as shown in (1) to (7). The formation of pores was evaluated based on the following criteria. The results are shown in Tables 1 to 3.

[0239] {Benchmark} Level 3 (0): The area of ​​the part with bubbles is less than 5% of the relative field of view.

[0240] Level 2 (△): Relative field of view, the area of ​​the part with bubbles is more than 5% and less than 20%.

[0241] Level 1 (×): Relative field of view, the area of ​​the part with bubbles is more than 20%.

[0242] [Evaluation of electrical connections] For the test connection structure of Example 23, after resin embedding, the laminated cross-section was exposed by mechanical grinding. The electrical connection of the counter electrode was evaluated using an optical microscope (named "VHX-8000", manufactured by KEYENCE) according to the following criteria. The results are shown in Table 3.

[0243] {Benchmark} Level 2: Solder-based connection of the opposing electrode was observed.

[0244] Level 1: No solder-based counter electrode connection was observed.

[0245] Furthermore, for the test connection structure of Example 24, the resistance between the opposing electrodes was evaluated using a digital multimeter (named "PC500a", manufactured by Sanwa Electric Instrument Co., Ltd.). The electrical connection of the opposing electrodes was evaluated according to the following criteria. The results are shown in Table 3.

[0246] {Benchmark} Level 2: The resistance value is displayed as a positive value (above 0).

[0247] Level 1: The resistance value is displayed as a value below 0.

[0248] [Table 1] [Table 2] [Table 3] [Table 4] It should be noted that the above-described invention is provided as an example of the implementation of this invention, but it is merely an example and not a limiting interpretation. Variations of this invention that are clearly apparent to those skilled in the art are included in the above claims.

[0249] Industrial availability The conductive resin composition, bonding sheet, method for manufacturing the conductive resin composition, method for manufacturing the bonding body, and bonding body of the present invention can be suitably used, for example, in the manufacture of electronic devices.

[0250] Explanation of reference numerals in the attached figures 1. Joining plate 2 1st base board 4 2nd base board 5 Solder particles 6-layered body 12 First Electrode 14. Second electrode 15. Columnar solder section 20. Assembly 25 Pressure Oven Claims (as amended under Article 19 of the Treaty) 1. A conductive resin composition comprising acid-treated solder particles, a resin component, and a flux containing carboxyl groups. The maximum value of the Mulliken charge of the carbon group of the carboxyl group in the flux is less than 0.5850. 2. The conductive resin composition of claim 1, wherein the flux content is 1 part by mass or more and 7 parts by mass or less relative to 100 parts by mass of the acid-treated solder particles. 3. The conductive resin composition of claim 1, wherein the flux is a carboxylic acid. 4. The conductive resin composition of claim 3, wherein the flux is a dicarboxylic acid. 5. A bonding sheet comprising the conductive resin composition according to any one of claims 1 to 4. 6. A method for manufacturing a conductive resin composition, comprising: The first step involves acid treating the solder particles using an acid treatment agent; and The second step involves mixing the acid-treated solder particles, resin components, and carboxyl-containing flux. The maximum value of the Mulliken charge of the carbon group of the carboxyl group in the flux is less than 0.585. 7. The method of manufacturing the conductive resin composition according to claim 6, wherein the acid treatment agent has a carboxyl group, and the maximum value of the Mulliken charge of the carbon of the carboxyl group exceeds 0.5850. 8. A method for manufacturing a joint, comprising: The third step involves preparing multiple substrates with multiple electrodes arranged in a planar direction. Step 4: Coating the conductive resin composition obtained by the manufacturing method of claim 6 or 7 to prepare the bonding sheet. In the fifth step, the two substrates are stacked with the bonding sheet sandwiched between their electrodes to create a laminate; and In the sixth step, the laminate is heated to melt the solder particles, thereby forming columnar solder portions in a manner that electrically connects the electrodes of the two substrates, and the resin components are cured. 9. The method for manufacturing the joint as claimed in claim 8, wherein the sixth step is performed in a pressure oven. 10. A joint having: A first substrate having a plurality of first electrodes arranged in a planar direction; A second substrate having a plurality of second electrodes arranged in the planar direction, the second substrate being configured at intervals in a thickness direction orthogonal to the planar direction such that the first electrodes are opposite to the second electrodes; and An adhesive layer, sandwiched between the first substrate and the second substrate, electrically connects the first electrode and the second electrode, which are opposed in the thickness direction, and bonds the first substrate and the second substrate. The adhesive layer is a cured product of the conductive resin composition according to any one of claims 1 to 4. The adhesive layer includes a columnar solder portion that electrically connects the first electrode and the second electrode, which are opposed in the thickness direction, and a cured resin.

Claims

1. A conductive resin composition comprising acid-treated solder particles, a resin component, and a flux containing carboxyl groups. The maximum value of the Mulliken charge of the carbon group of the carboxyl group in the flux is less than 0.5850.

2. The conductive resin composition according to claim 1, wherein, The flux content is between 1 and 7 parts by mass relative to 100 parts by mass of the acid-treated solder particles.

3. The conductive resin composition according to claim 1, wherein, The flux is a carboxylic acid.

4. The conductive resin composition according to claim 3, wherein, The flux is a dicarboxylic acid.

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

6. A method for manufacturing a conductive resin composition, comprising: The first step involves acid treating the solder particles using an acid treatment agent; and The second step involves mixing the acid-treated solder particles, resin components, and carboxyl-containing flux. The maximum value of the Mulliken charge of the carbon group of the carboxyl group in the flux is less than 0.

585.

7. The method for manufacturing the conductive resin composition according to claim 6, wherein, The acid treatment agent has a carboxyl group, and the maximum value of the Mulliken charge on the carbon of the carboxyl group exceeds 0.5850.

8. A method for manufacturing a joint, comprising: The third step involves preparing multiple substrates with multiple electrodes arranged in a planar direction. Step 4: Coating the conductive resin composition obtained by the manufacturing method of claim 6 or 7 to prepare the bonding sheet. In the fifth step, the two substrates are stacked with the bonding sheet sandwiched between their electrodes to create a laminate; and In the sixth step, the laminate is heated to melt the solder particles, thereby forming columnar solder portions in a manner that electrically connects the electrodes of the two substrates, and the resin components are cured.

9. The method for manufacturing the joint as described in claim 8, wherein, The sixth step is carried out in a pressure oven.

10. A joint having: A first substrate having a plurality of first electrodes arranged in a planar direction; A second substrate having a plurality of second electrodes arranged in the planar direction, the second substrate being configured at intervals in a thickness direction orthogonal to the planar direction such that the first electrodes are opposite to the second electrodes; and An adhesive layer, sandwiched between the first substrate and the second substrate, electrically connects the first electrode and the second electrode, which are opposed in the thickness direction, and bonds the first substrate and the second substrate together. The adhesive layer is the cured product of the bonding sheet as described in any one of claims 1 to 4. The adhesive layer includes a columnar solder portion that electrically connects the first electrode and the second electrode, which are opposed in the thickness direction, and a cured resin.

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