Conductive composition

Abstract

The conductive composition contains an epoxy compound, an imidazole compound, a phenolic curing agent, and conductive particles. In the epoxy compound, the content ratio of the naphthalene skeleton-containing epoxy resin is 10-30% by mass, the content ratio of the glycidyl amine-based epoxy resin is 40-90% by mass, and the content ratio of the reactive diluent having 1-2 glycidyl ether functional groups in the aliphatic hydrocarbon chain is 10% by mass or less. The imidazole compound contains at least one substance selected from the group consisting of a 2-undecylimidazole, a 2-heptadecyl limidazole, a 4-methyl-2-phenylimidazole, and a 2-phenyl-4-methyl-5-hydroxymethyl limidazole. The content of the imidazole compound is 3-10 parts by mass and the content of the phenolic curing agent is 10-20 parts by mass per 100 parts by mass of the epoxy compound. The content of the conductive particles in the conductive composition is 82-90% by mass.

Description

Technical Field

[0001] The present invention relates to conductive compositions. Background Art

[0002] In recent years, in electronic devices such as mobile phones and / or tablet terminals, as semiconductor elements and / or chip components have become smaller and / or more functional, there has been a demand for high-density mounting of multiple electronic components, and the demand for multilayer substrates has further increased.

[0003] In order to electrically connect layers in a multilayer substrate, a method is used in which through-holes are formed between the layers and filled with a conductive paste. As such a conductive paste, the one described in Patent Document 1 is known.

[0004] Furthermore, as conductive adhesives for connecting substrates and electronic components, compositions such as those described in Patent Documents 2 and 3 are known.

[0005] However, in recent years, as semiconductor elements and / or chip components have become smaller and / or more powerful, the heat generated by these elements and / or chip components has increased. Furthermore, these components undergo repeated heat treatments at temperatures between 150°C and 300°C during their manufacturing process, requiring them to exhibit heat resistance in high-temperature environments. Consequently, conductive compositions with both excellent electrical conductivity and excellent adhesion in high-temperature environments are required.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-302904

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2005-126658

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2009-001661 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a conductive composition having excellent conductivity and good adhesion to a substrate in a high-temperature environment.

[0013] Solutions for solving problems

[0014] The present invention includes the following embodiments.

[0015] [1] A conductive composition comprising an epoxy compound, an imidazole compound, a phenolic curing agent, and conductive particles.

[0016] The epoxy compound comprises 10 to 30% by mass of a naphthalene skeleton-containing epoxy resin, 40 to 90% by mass of a glycidylamine-based epoxy resin, and 10% by mass or less of a reactive diluent having 1 to 2 glycidyl ether functional groups in an aliphatic hydrocarbon chain.

[0017] The imidazole compound contains at least one selected from the group consisting of 2-undecyl imidazole, 2-heptadecylimidazole, 4-methyl-2-phenylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole,

[0018] The content of the imidazole compound is 3 to 10 parts by mass relative to 100 parts by mass of the epoxy compound.

[0019] The content of the phenolic curing agent is 10 to 20 parts by mass relative to 100 parts by mass of the epoxy compound.

[0020] The content of the conductive particles in the conductive composition is 82 to 90% by mass.

[0021] [2] The conductive composition according to [1], wherein the cured product obtained by heating at 80°C for 30 minutes and then at 180°C for 60 minutes has a glass transition temperature of 150°C or higher.

[0022] Effects of the Invention

[0023] According to the conductive composition of the present invention, excellent conductivity can be obtained, and good adhesion to a substrate can be obtained in a high-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 These are a side view and a front view schematically showing a test piece used for evaluating adhesion. DETAILED DESCRIPTION

[0025] The conductive composition of the present invention contains an epoxy compound, an imidazole compound, a phenolic curing agent, and conductive particles, and is a thermosetting conductive composition.

[0026] The epoxy compound includes a naphthalene skeleton-containing epoxy resin and a glycidylamine-based epoxy resin, and optionally contains a reactive diluent having 1 to 2 glycidyl ether functional groups in an aliphatic hydrocarbon chain. That is, the reactive diluent is not an essential component and may not be contained.

[0027] As the epoxy resin containing a naphthalene skeleton, any epoxy resin having an epoxy group and a naphthalene skeleton in the molecule can be used. Examples thereof include naphthalene-type epoxy resins, dihydroxynaphthalene-type epoxy resins, polyhydroxybinaphthyl-type epoxy resins, naphthol-type epoxy resins, binaphthol-type epoxy resins, naphthylene ether-type epoxy resins, naphthol novolac-type epoxy resins, and naphthalene-type epoxy resins obtained by a condensation reaction of polyhydroxynaphthalene with aldehydes. Any one of these can be used, or two or more can be used in combination. Commercially available epoxy resins containing a naphthalene skeleton include, for example, EPICLON HP-4700, EPICLON HP-4710, EPICLON HP-5000, and EPICLON HP-6000 manufactured by DIC Corporation, and NC-7000-L and NC-7300-L manufactured by Nippon Kayaku Co., Ltd.

[0028] The epoxy equivalent of the naphthalene skeleton-containing epoxy resin is not particularly limited, but is preferably 160 to 260 g / eq, and more preferably 160 to 240 g / eq.

[0029] As a glycidylamine epoxy resin, any epoxy resin containing at least one glycidylamino group can be used, wherein the glycidylamino group contains one epoxy group. Examples of such compounds include tetraglycidyldiaminophenylmethane epoxy resins, tetraglycidyldiaminodiphenylmethane epoxy resins, and triglycidylaminophenol epoxy resins. Any one of these can be used, or two or more can be used in combination. Commercially available glycidylamine epoxy resins include, for example, “jER630” manufactured by Mitsubishi Chemical Corporation, “EPOTOHTO YH-404” and “EPOTOHTO YH-434L” manufactured by Nippon Steel Chemicals Co., Ltd., “SUMI-EPOXY ELM-434” and “SUMI-EPOXY ELM-100” manufactured by Sumitomo Chemical Co., Ltd., and “EP-3950S” manufactured by ADEKA Co., Ltd.

[0030] The epoxy equivalent of the glycidylamine epoxy resin is not particularly limited, but is preferably 90 to 120 g / eq, and more preferably 90 to 110 g / eq.

[0031] As a reactive diluent, any compound having one or two glycidyl ether functional groups in an aliphatic hydrocarbon chain can be used. The aliphatic hydrocarbon chain preferably has 3 to 13 carbon atoms, more preferably 6 to 13 carbon atoms. Examples of such compounds include "ADEKA GLYCIROL ED-502" and "ADEKA GLYCIROL ED-503G" manufactured by ADEKA Co., Ltd., "YED 111N" and "YED 216M" manufactured by Mitsubishi Chemical Corporation, and "DY-BP," "Epogosey (registered trademark) BD (D)," "Epogosey (registered trademark) NPG (D)," and "Epogosey (registered trademark) HD ​​(D)" manufactured by Yokkaichi Synthetic Co., Ltd.

[0032] The epoxy equivalent of the reactive diluent is not particularly limited, but is preferably 100 to 320 g / eq, and more preferably 100 to 150 g / eq.

[0033] The epoxy compound may include a naphthalene skeleton-containing epoxy resin, a glycidylamine-based epoxy resin, and epoxy compounds other than the above-mentioned reactive diluents, within a range not impairing the effects of the present invention. Examples of such epoxy compounds include bisphenol A epoxy resin, bisphenol F epoxy resin, cresol novolac epoxy resin, phenol novolac epoxy resin, biphenyl epoxy resin, triphenylmethane epoxy resin, and dicyclopentadiene epoxy resin.

[0034] The content of the naphthalene skeleton-containing epoxy resin in the epoxy compound is 10 to 30% by mass, preferably 10 to 25% by mass, and more preferably 15 to 25% by mass. When the content of the naphthalene skeleton-containing epoxy resin is within the above range, the glass transition temperature (Tg) of the cured product obtained by heating the conductive composition at 80°C for 30 minutes and then at 180°C for 60 minutes is high, and excellent adhesion is easily achieved.

[0035] The content of the glycidylamine epoxy resin in the epoxy compound is 40 to 90% by mass, preferably 60 to 80% by mass, and more preferably 60 to 70% by mass. When the content of the glycidylamine epoxy resin is within this range, the glass transition temperature (Tg) of the cured product obtained by heating the conductive composition at 80°C for 30 minutes and then at 180°C for 60 minutes is high, and excellent adhesion is easily achieved.

[0036] The content of the reactive diluent in the epoxy compound is 10% by mass or less, preferably 8% by mass or less, and more preferably 0 to 5% by mass. When the content of the reactive diluent is within the above range, the glass transition temperature (Tg) of the cured product obtained by heating the conductive composition at 80°C for 30 minutes and then at 180°C for 60 minutes is high, and excellent adhesion is easily achieved.

[0037] The epoxy equivalent of the epoxy compound is not particularly limited, but is preferably 95 to 160 g / eq, and more preferably 100 to 130 g / eq.

[0038] The imidazole compound contains at least one selected from the group consisting of 2-undecylimidazole, 2-heptadecylimidazole, 4-methyl-2-phenylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Other imidazole compounds may be contained without impairing the effects of the present invention. Examples of such imidazole compounds include imidazoles (e.g., alkylimidazoles such as 2-methylimidazole, 2-phenylimidazole, and 2-ethyl-4-methylimidazole; arylimidazoles such as 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 1-benzyl-2-phenylimidazole); and salts of imidazoles (e.g., organic salts such as formates, phenolates, and phenol novolac salts; and salts such as carbonates).

[0039] The content of the imidazole compound is 3 to 10 parts by mass, preferably 3 to 8 parts by mass, and more preferably 3 to 5 parts by mass, relative to 100 parts by mass of the epoxy compound. When the content of the imidazole compound is 3 parts by mass or greater, excellent conductivity is easily obtained, while when it is 10 parts by mass or less, excellent adhesion is easily obtained.

[0040] The content of 2-undecyl imidazole, 2-heptadecylimidazole, 4-methyl-2-phenylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole in the imidazole compound is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass.

[0041] Examples of phenolic curing agents include novolac-type phenolic resins such as phenol novolac resins, cresol novolac resins, tert-butylphenol novolac resins, nonylphenol novolac resins, naphthol novolac resins, trisphenol novolac resins, and tetrakisphenol novolac resins; trisphenol alkane-type phenolic resins such as trisphenol methane-type resins and trisphenol propane-type resins; aralkyl-type phenolic resins such as phenol aralkyl resins having a phenylene skeleton and / or a diphenylene skeleton, naphthol aralkyl resins, and biphenyl aralkyl resins; and polyhydroxystyrene resins such as poly(p-hydroxystyrene). Among these, naphthol aralkyl resins are preferred.

[0042] The content of the phenolic curing agent is 10 to 20 parts by mass, preferably 10 to 18 parts by mass, and more preferably 10 to 15 parts by mass, relative to 100 parts by mass of the epoxy compound. When the content of the phenolic curing agent is within this range, powder contact due to cure shrinkage is achieved, and excellent conductivity is easily achieved.

[0043] The conductive particles are not particularly limited. Examples thereof include copper particles, silver particles, nickel particles, silver-coated copper particles, gold-coated copper particles, silver-coated copper alloy particles, silver-coated nickel particles, and gold-coated nickel particles. Any one of these particles may be used, or two or more of these particles may be used in combination. Among these particles, the conductive particles are preferably at least one selected from the group consisting of copper particles, silver-coated copper particles, and silver-coated copper alloy particles.

[0044] Silver-coated copper particles comprise copper particles and a silver layer or a silver-containing layer coating at least a portion of the copper particles. Silver-coated copper alloy particles comprise copper alloy particles and a silver layer or a silver-containing layer coating at least a portion of the copper alloy particles. The copper alloy particles contain 0.5 to 25% by mass of zinc and / or 0.5 to 30% by mass of nickel, with the remainder consisting of copper, which may also contain unavoidable impurities. The content of the silver-containing layer in the silver-coated copper particles and the silver-coated copper alloy particles is not particularly limited, but is preferably 4 to 24% by mass. The silver content in the silver-containing layer is not particularly limited, but is preferably 90 to 100% by mass.

[0045] The conductive particles may be spherical, flake-like (scale-like), dendritic, or fibrous in shape. Spherical and / or flake-like (scale-like) conductive particles are preferred. It should be noted that the term "spherical" encompasses not only generally true spherical particles (atomized powder), but also generally polyhedral particles (reduced powder) and / or particles of irregular shape (electrolytic powder).

[0046] The conductive particles are contained in the conductive composition at a ratio of 82 to 90% by mass, preferably 84 to 88% by mass, and more preferably 84 to 86% by mass. A content of 82% or more of the conductive particles tends to provide excellent conductivity, while a content of 90% or less of the conductive particles tends to provide excellent adhesion.

[0047] The average particle size of the conductive particles is not particularly limited, but is preferably 2 to 10 μm. When the average particle size is 2 μm or greater, the conductive particles have good dispersibility, can be prevented from agglomerating, and are less susceptible to oxidation. When the average particle size is 10 μm or less, excellent adhesion is easily achieved.

[0048] Here, in this specification, the average particle size refers to the particle size of the number-based average particle size D50 (median diameter) measured by a laser diffraction / scattering method.

[0049] The viscosity of the conductive composition can be appropriately adjusted depending on the intended use, such as filling through-holes formed between layers of a multilayer substrate and / or as an adhesive between a substrate and an electronic component, or the equipment used for filling and / or coating. General guidelines are as follows. The viscosity can be measured using a cone-plate type rotational viscometer (so-called cone-plate viscometer), although the method is not particularly limited.

[0050] When measured using a cone-plate rotational viscometer, using a Brookfield cone spindle CP52 (cone angle: 3°, cone radius: 12 mm), at a measurement temperature of 25°C and 5 rpm, the viscosity is preferably 30 to 60 Pa·s, more preferably 30 to 50 Pa·s. When the viscosity is within this range, excellent filling properties into through-holes are easily achieved.

[0051] The conductive composition of the present invention may contain known additives such as a defoaming agent, a thickener, a binder, a filler, a flame retardant, and a colorant, within the range not impairing the purpose of the invention.

[0052] From the viewpoint of adhesion, the conductive composition of the present invention is heated at 80°C for 30 minutes and then at 180°C for 60 minutes to obtain a cured product having a glass transition temperature of preferably 150°C or more, more preferably 170°C or more. It should be noted that the upper limit of the glass transition temperature is not particularly limited, and for example, it may be 250°C. Here, in this specification, the glass transition temperature (Tg) is a value measured using a dynamic viscoelasticity measuring device "DMA242E Artemis" manufactured by NETZSCH Japan Co., Ltd. under the conditions of a frequency of 1 Hz, a dynamic load of 5 N, a static load of 1 N, a measurement temperature of 25 to 260°C, and a heating rate of 5°C / min. It should be noted that the size of the cured product for measuring the glass transition temperature can be set to a length of 20 to 25 mm, a width of 4 to 5 mm, and a thickness of 0.5 to 1.5 mm.

[0053] Example

[0054] Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited to the following. In addition, unless otherwise specified, "parts" or "%" are based on mass.

[0055] Conductive compositions were obtained by blending the components in the ratios shown in Tables 1 to 3. The components used are as follows.

[0056] ·Naphthalene skeleton-containing epoxy resin 1: DIC Corporation "HP-4710", epoxy equivalent = 170 g / eq

[0057] ·Naphthalene skeleton-containing epoxy resin 2: "NC-7000-L" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent weight = 235 g / eq

[0058] Glycidylamine epoxy resin 1: "jER 630" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight = 95 g / eq

[0059] Glycidylamine epoxy resin 2: "YH-434L" manufactured by Nippon Steel Chemicals Co., Ltd., epoxy equivalent weight = 115 g / eq

[0060] Dicyclopentadiene epoxy resin: "EP-4088S" manufactured by ADEKA Co., Ltd., epoxy equivalent weight = 170 g / eq

[0061] Reactive diluent 1: "ED-503G" manufactured by ADEKA Co., Ltd., aliphatic hydrocarbon chain carbon number = 6, epoxy equivalent = 135 g / eq

[0062] Reactive diluent 2: "ED-502" manufactured by ADEKA Co., Ltd., aliphatic hydrocarbon chain with 12 to 13 carbon atoms, epoxy equivalent weight 320 g / eq

[0063] Imidazole compound 1: 2-undecyl imidazole

[0064] Imidazole compound 2: 2-heptadecylimidazole

[0065] Imidazole compound 3: 4-methyl-2-phenylimidazole

[0066] Imidazole compound 4: 2-phenyl-4-methyl-5-hydroxymethylimidazole

[0067] Imidazole compound 5: 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine

[0068] Phenolic curing agent: Naphthol-type phenolic resin, "MEH-7000" manufactured by Meiwa Chemicals Co., Ltd.

[0069] Conductive particles: Silver-coated copper particles, average particle size = 4-6 μm, spherical

[0070] Evaluations of Examples and Comparative Examples were performed as follows. The results are shown in Tables 1 to 3.

[0071] (1) Resistivity

[0072] The conductive composition was line-printed on a glass epoxy substrate (length 60 mm, width 1 mm, thickness about 100 μm), pre-cured by heating at 80°C for 30 minutes, and then cured by heating at 180°C for 60 minutes to prepare an evaluation substrate with a conductive pattern. Next, the resistance (R) between the two ends of the conductive pattern was measured using a tester. The cross-sectional area (S, cm 2 ) and length (L, cm) were calculated using the following formula (1). It should be noted that 15 conductive patterns were formed by printing 5 lines each on three glass epoxy substrates, and the average resistivity of these patterns was calculated. A resistivity of 2.5E-04 Ω·cm or less was evaluated as excellent conductivity and designated "A." A resistivity greater than 2.5E-04 Ω·cm and less than 5.0E-04 Ω·cm was evaluated as slightly excellent conductivity and designated "B." A resistivity greater than 5.0E-04 Ω·cm was evaluated as poor conductivity and designated "C."

[0073]

[0074] (2) Glass transition temperature (Tg)

[0075] The conductive composition was pre-cured by heating at 80°C for 30 minutes and then fully cured by heating at 180°C for 60 minutes, producing a cured product with a length of 25 mm, a width of 5 mm, and a thickness of 1 mm. The cured product was clamped with a chuck distance of 15 mm in a dynamic viscoelasticity measuring apparatus "DMA 242E Artemis" manufactured by NETZSCH Japan Co., Ltd., and measured at a frequency of 1 Hz, a dynamic load of 5 N, a static load of 1 N, a measurement temperature of 25-260°C, a heating rate of 5°C / min, and a stress-strain mixed measurement mode. The peak tan δ value was defined as the glass transition temperature.

[0076] (3) Adhesion

[0077] A tough copper plate 1 (length 100 mm, width 25 mm, thickness 1.6 mm) specified in JIS H 3100 was used. Figure 1 As shown, a conductive composition was applied to the area 12.5 mm ± 0.5 mm from the end of the tough copper plate 1 (bonding area 2), and two tough copper plates were bonded together. The test piece was prepared by heating at 80°C for 30 minutes to pre-cure it and heating at 180°C for 60 minutes to fully cure it. Using a tensile testing machine, as shown in FIG. Figure 1As shown, the tensile tester is clamped in an area of ​​38.0 mm ± 1.0 mm from both ends of the test piece (clamping area 3) to perform a tensile test. The maximum load until the test piece is broken is measured, and the shear bond strength is calculated by the following formula. If the shear bond strength is 5 MPa or more, the adhesion is evaluated as excellent and is expressed as "A". If it is 3 MPa or more and less than 5 MPa, the adhesion is evaluated as slightly excellent and is expressed as "B". If it is less than 3 MPa, the adhesion is evaluated as poor and is expressed as "C".

[0078] Shear bond strength (MPa) = maximum load (N) / shear area of ​​test piece (mm 2 )

[0079] (4) Adhesion under high temperature environment

[0080] Evaluation was performed in the same manner as the above-mentioned evaluation of adhesion except that the measurement was performed in an environment of 150° C. The test piece temperature was set at 150° C., and the measurement was performed after the test piece was clamped in a tensile testing machine for 10 minutes.

[0081] [Table 1]

[0082]

[0083] [Table 2]

[0084]

[0085] [Table 3]

[0086]

[0087] From the results shown in Tables 1 to 3, it was confirmed that the conductive composition of each example achieved excellent conductivity and had good adhesion in a high-temperature environment.

[0088] Comparative Example 1 is an example in which the content of the imidazole compound exceeded the upper limit, and the adhesion under a high-temperature environment was poor.

[0089] Comparative Example 2 is an example in which the imidazole compound is not the prescribed compound, and the resistivity is poor.

[0090] Comparative Example 3 is an example in which no phenolic curing agent is contained, and the resistivity is poor.

[0091] Comparative Example 4 is an example in which the content of the phenolic curing agent exceeded the upper limit, and the adhesion under a high-temperature environment was poor.

[0092] Comparative Example 5 is an example in which the content of the conductive particles is less than the lower limit, and the resistivity is poor.

[0093] Comparative Example 6 is an example in which the content ratio of the glycidylamine-based epoxy resin is less than the lower limit value, and the adhesiveness in a high-temperature environment is poor.

[0094] Comparative Example 7 is an example in which the content ratio of the naphthalene skeleton-containing epoxy resin is less than the lower limit value, and the adhesion under a high-temperature environment is poor.

[0095] Comparative Example 8 is an example in which the content ratio of the naphthalene skeleton-containing epoxy resin exceeded the upper limit, and the adhesion under a high-temperature environment was poor.

[0096] Comparative Example 9 is an example in which the content of the reactive diluent exceeded the upper limit, and the adhesion under a high-temperature environment was poor.

[0097] It should be noted that the various numerical ranges described in the specification can be arbitrarily combined with their upper and lower limits, and all combinations thereof are described in this specification as preferred numerical ranges. In addition, the description of the numerical range of "X to Y" means greater than X and less than Y.

[0098] Description of Reference Numerals

[0099] 1: Tough copper plate

[0100] 2: Bonding area

[0101] 3: Clamping area

Claims

1. A conductive composition comprising an epoxy compound, an imidazole compound, a phenolic curing agent and conductive particles, The epoxy compound comprises 10 to 30% by mass of a naphthalene skeleton-containing epoxy resin, 40 to 90% by mass of a glycidylamine-based epoxy resin, and 10% by mass or less of a reactive diluent having 1 to 2 glycidyl ether functional groups in an aliphatic hydrocarbon chain. The imidazole compound contains at least one selected from the group consisting of 2-undecyl imidazole, 2-heptadecylimidazole, 4-methyl-2-phenylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole, The content of the imidazole compound is 3 to 10 parts by mass relative to 100 parts by mass of the epoxy compound. The content of the phenolic curing agent is 10 to 20 parts by mass relative to 100 parts by mass of the epoxy compound. The content of the conductive particles in the conductive composition is 82 to 90% by mass. 2 . The conductive composition according to claim 1 , wherein a cured product obtained by heating at 80° C. for 30 minutes and then at 180° C. for 60 minutes has a glass transition temperature of 150° C. or higher.

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