JP2015160932A - Conductive adhesive and electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive adhesive having high heat resistance, and an electronic device using the same.SOLUTION: The conductive adhesive contains: (A) a glycidyl ether compound which is liquid at 25°C, is obtained by oxidizing a carbon-carbon double bond of an allyl group of an allyl ether compound with an oxidant, and does not substantially contain a carbon-chlorine bond; (B) a phenolic resin-based curing agent which is solid at 25°C and has an average molecular weight of 350 or more; (C) a curing accelerator; and (D) a conductive filler. The phenolic resin-based curing agent (B) is contained in an amount of 50-150 pts.mass based on 100 pts.mass of the glycidyl ether compound (A).

Description

  The present invention relates to a conductive adhesive and an electronic device using them.

  In recent years, conductive adhesives are frequently used in place of solder for assembling semiconductor elements and various electric / electronic components or bonding them to substrates.

For example, Patent Document 1 below includes an epoxy resin, a curing agent, a curing accelerator, a silane coupling agent, and a conductive filler, and the epoxy resin has a bifunctional or higher functional group at a viscosity of 250 mPa · s or less at 25 ° C. 10 to 90% by mass of a liquid epoxy resin having a viscosity of 10000 Pa · s or less at 25 ° C., and the content of the liquid phenol resin is The conductive filler is (a) D ₅₀ is ₅ to 10 μm, the tap density is 4.0 g / cm ³ or more, and the specific surface area is 0, based on the total amount of the epoxy resin and the curing agent. a first electrically conductive filler scaly .35m ² / g or less, and _{(b) D 50} is 1 to 5 [mu] m, a specific surface area of 0.6 m ² / g or _more, D 90 _{/ D 10} of 8 or more Na It consists of the 2nd conductive filler which has a particle size distribution, The mixing ratio of (b) / (a) is 0.1-1, and content of the whole conductive filler is 85-95 mass% with respect to the whole quantity. A conductive adhesive is described.

  Patent Document 2 listed below discloses a metal filler containing copper as a conductive adhesive having sufficient strength and conductivity, an epoxy compound, a novolac type phenol resin, and a low molecular weight polyhydric phenol compound. And a conductive adhesive containing a curing agent as essential components is described. Patent Document 3 listed below describes a conductive adhesive containing an epoxy resin that is liquid at room temperature and a phenol resin that is liquid at room temperature as a conductive adhesive having better adhesive strength.

JP 2009-1604 A JP 2000-192000 A JP 2009-7453 A

  The conventional technology has a problem that the heat resistance of the conductive adhesive cannot be secured sufficiently.

  An object of the present invention is to provide a conductive adhesive having high heat resistance and an electronic device using them.

  In order to achieve the above object, one embodiment of the present invention is a conductive adhesive, (A) a glycidyl ether compound that is liquid at 25 ° C. and substantially free of carbon-chlorine bonds, B) A phenol resin-based curing agent having an average molecular weight of 350 or more that is solid at 25 ° C., (C) a curing accelerator, and (D) a conductive filler, and with respect to 100 parts by mass of the (A) glycidyl ether compound. And (B) 50 to 150 parts by mass of a phenol resin-based curing agent.

  The (A) glycidyl ether compound is preferably a polyvalent glycidyl ether of an aliphatic polyhydric alcohol having 3 to 30 carbon atoms. The (A) glycidyl ether compound is preferably obtained by reacting the carbon-carbon double bond of the allyl group of the allyl ether compound with an oxidizing agent.

  The viscosity of the (A) glycidyl ether compound at 25 ° C. is preferably 1 mPa · s to 1000 mPa · s.

  The (A) glycidyl ether compound includes 1,4-cyclohexanedimethanol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, ditrimethylolpropane tetraglycidyl ether, diglycerin tetra. It is preferable to include at least one selected from the group consisting of glycidyl ether, dipentaerythritol hexaglycidyl ether, and sorbitol hexaglycidyl ether.

  The (B) phenol resin-based curing agent preferably contains at least one selected from the group consisting of phenol novolak resins, cresol novolak resins, triphenylmethane type phenol resins, and dicyclopentadiene-modified phenol resins. It is.

  The (C) curing accelerator is preferably at least one selected from the group consisting of imidazole compounds and derivatives thereof, phosphine compounds and derivatives thereof, and tertiary amines and derivatives thereof.

  Moreover, it is suitable that 0.1-10 mass parts of said (C) hardening accelerators are included with respect to a total of 100 mass parts of said (A) glycidyl ether compound and (B) phenol resin type hardening | curing agent.

  It is preferred that the conductive adhesive does not contain a solvent and a reactive diluent.

  In addition, the conductive filler (D) includes at least one metal selected from the group consisting of gold, silver, copper, nickel, aluminum, and palladium, or particles or fibers made of an alloy of the plurality of metals, and the metal surface. Metal particles or fibers plated with gold, palladium, or silver, resin core balls plated with nickel, gold, palladium, or silver on resin balls, carbon or graphite particles or fibers, or the metal particles It is preferable that the surface of the core ball, carbon or graphite particles is coated with an insulating resin thin film.

  Moreover, it is suitable that the total content of the (A) glycidyl ether compound, (B) phenol resin-based curing agent and (C) curing accelerator in the conductive adhesive is 5 to 90% by mass.

  In addition, another embodiment of the present invention is an electronic device, wherein a semiconductor element, a solar panel, a thermoelectric element, a chip part, a discrete part, or a combination thereof is mounted on a substrate by the conductive adhesive. It is characterized by.

  Still another embodiment of the present invention is an electronic device, wherein the conductive adhesive is used to form a film antenna, a keyboard membrane, a touch panel, an RFID antenna, and connect to a substrate. To do.

  According to the present invention, it is possible to realize a conductive adhesive having high heat resistance and an electronic device using them.

In peak 1 (CDMDG) in the total ion chromatogram and chromatogram obtained by gas chromatography / mass spectrometry (GC / MS) of 1,4-cyclohexanedimethanol diglycidyl ether (CDMDG) obtained in Production Example 2 It is a figure which shows a mass spectrum. It is a figure which shows the mass spectrum in the peak 1 (GLYG) in the total ion chromatogram obtained by gas chromatography / mass spectrometry (GC / MS) of the glycerol triglycidyl ether (GLYG) obtained in manufacture example 3. is there. The total ion chromatogram obtained by size exclusion chromatography / mass spectrometry (SEC / MS) of the pentaerythritol tetraglycidyl ether (PETG) obtained in Production Example 4 and fractions 1 to 4 in the chromatogram (fraction 1: (Retention time 11-12 minutes, fraction 2: retention time 12-13 minutes, fraction 3: retention time 13-14 minutes, fraction 4: retention time 14-15 minutes). It is a figure which shows the structure of the circuit sample used in the Example. It is explanatory drawing of the shear strength measuring method implemented in the Example.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described.

  The conductive adhesive according to the embodiment includes (A) a glycidyl ether compound that is liquid at 25 ° C. and substantially free of carbon-chlorine bonds, and (B) an average molecular weight that is solid at 25 ° C. is 350 or more. 50-150 mass of (B) phenol resin hardening agent is included with respect to 100 mass parts of said (A) glycidyl ether compounds, including a phenol resin hardening agent, (C) hardening accelerator, and (D) conductive filler. It is characterized by containing a part. In the present specification, (A) a glycidyl ether compound, (B) a phenol resin-based curing agent and (C) a curing accelerator may be collectively referred to as a resin component constituting a conductive adhesive and referred to as a resin composition.

(A) Glycidyl ether compound The glycidyl ether compound contained in the conductive adhesive of the present embodiment is a compound that is substantially liquid at 25 ° C. and does not contain a carbon-chlorine bond in the molecule. The glycidyl ether compound used in the conventional epoxy resin composition is mainly produced by a condensation reaction of an aliphatic alcohol or phenol and epichlorohydrin, and at that time, it is represented by the formula (1) in the molecule. A compound having a terminal group containing a carbon-chlorine bond is produced as a by-product. The separation and removal of these by-products are very laborious and extremely difficult to remove completely. When a glycidyl ether compound mixed with by-products is used, the viscosity of the resin composition increases, and the obtained cured product has a low glass transition temperature and poor heat resistance.

  In this embodiment, “substantially free of carbon-chlorine bond” means that no peak corresponding to the compound containing carbon-chlorine bond and a fragment thereof is observed in the mass spectrum of the glycidyl ether compound. More specifically, in the mass spectrum of a glycidyl ether compound, a peak corresponding to a compound containing a carbon-chlorine bond and a fragment thereof produced as a by-product when producing a glycidyl ether compound by an epichlorohydrin method using an aliphatic alcohol as a raw material. Means not allowed.

Examples of the method for producing the glycidyl ether compound that does not generate the by-product used in the present embodiment include a method of oxidizing the carbon-carbon double bond of the allyl group of the allyl ether compound with an oxidizing agent, more specifically. Can be produced, for example, by the following method.
1) A method of oxidizing a carbon-carbon double bond of an allyl ether compound using a peracid (such as peracetic acid) as an oxidizing agent (for example, JP-A-7-145221)
2) A method of oxidizing a carbon-carbon double bond of an allyl ether compound using hydrogen peroxide (more specifically, an aqueous hydrogen peroxide solution) as an oxidizing agent using a catalyst such as tungsten or zeolite (for example, JP-A-60). -60123)
3) A method in which the carbon-carbon double bond of an allyl ether compound is oxidized in a basic atmosphere in the presence of acetonitrile using hydrogen peroxide (more specifically, an aqueous hydrogen peroxide solution) as an oxidizing agent (for example, Japanese Patent Laid-Open No. Sho 59). No. 227872)

  The glycidyl ether compound obtained by the above method is preferably used after purification by distillation, adsorbent treatment or the like, if necessary.

  The glycidyl ether compound used in this embodiment is liquid at 25 ° C. The viscosity of the glycidyl ether compound at 25 ° C. is preferably in the range of 1 mPa · s to 1000 mPa · s. In some preferred embodiments, the viscosity at 25 ° C. of the glycidyl ether compound is 5 mPa · s or more, or 10 mPa · s or more, 500 mPa · s or less, or 300 mPa · s or less. The epoxy equivalent of the glycidyl ether compound is preferably in the range of 80 to 300 g / equivalent, and more preferably in the range of 90 to 200 g / equivalent. When the epoxy equivalent is less than 80 g / equivalent, the impact resistance of the cured product is reduced. On the other hand, when it exceeds 300 g / equivalent, the viscosity when the curing agent is added becomes very high, and the handleability deteriorates.

  The glycidyl ether compound used in the present embodiment preferably has an average of two or more glycidyl groups in one molecule in order to express good mechanical strength as a cured product. Among them, polyhydric allyl ethers of aliphatic polyhydric alcohols having 3 to 30 carbon atoms (in which at least two of the hydroxyl groups of the polyhydric alcohol are substituted with allyloxy groups, some hydroxyl groups remain. It is particularly preferable to use a polyhydric glycidyl ether of an aliphatic polyhydric alcohol having 3 to 30 carbon atoms obtained by epoxidizing a carbon-carbon double bond (including those) with an oxidizing agent.

  Specifically, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,9-nonanediol diglycidyl ether, 1,10-decane Diol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, tricyclodecane dimethanol diglycidyl ether , Hydrogenated bisphenol A diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tet Glycidyl ether, ditrimethylolpropane tetraglycidyl ether, diglycerin tetraglycidyl ether, erythritol tetraglycidyl ether, xylitol pentaglycidyl ether, dipentaerythritol pentaglycidyl ether, dipentaerythritol hexaglycidyl ether, sorbitol hexaglycidyl ether, inositol pentaglycidyl ether, Examples include inositol hexaglycidyl ether. Among these, when considering the viscosity of the compound and the heat resistance of the cured product, 1,4-cyclohexanedimethanol diglycidyl ether, tricyclodecane dimethanol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether , Pentaerythritol tetraglycidyl ether, ditrimethylolpropane tetraglycidyl ether, diglycerin tetraglycidyl ether, dipentaerythritol hexaglycidyl ether, and sorbitol hexaglycidyl ether are preferable, 1,4-cyclohexanedimethanol diglycidyl ether, tricyclodecanedi Methanol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, Fine pentaerythritol tetraglycidyl ether is particularly preferred.

(B) Phenol resin-based curing agent The conductive adhesive of this embodiment includes (B) a phenol resin-based curing agent for reacting with the (A) glycidyl ether compound to form a cured product. The (B) phenol resin-based curing agent used in the present invention is solid at 25 ° C. and has an average molecular weight of 350 or more. Since the resin has high rigidity as compared with the case of using a liquid phenol-based curing agent, it is possible to obtain a cured product having a high glass transition temperature by restricting free rotation of molecules. A phenol resin-based curing agent having an average molecular weight of less than 350 or a low-molecular phenol-based curing agent is not preferable because of poor adhesive strength during curing.

  As the phenol resin-based curing agent, it is preferable to use a compound having two or more phenolic hydroxyl groups in one molecule. Specific examples include phenol novolac resins, cresol novolac resins, triphenylmethane type phenol resins, dicyclopentadiene-modified phenol resins, phenol aralkyl resins, zyloc type phenol resins, and terpene type phenol resins. Among these, a phenol novolak resin, a cresol novolak resin, a triphenylmethane type phenol resin, and a dicyclopentadiene-modified phenol resin are particularly preferable in view of compatibility with glycidyl ether and heat resistance. These may be used alone or in combination of two or more. Since these phenol resin-based curing agents have good compatibility with the above-mentioned glycidyl ether compound, they can be dissolved uniformly without using a solvent and / or a reactive diluent to obtain a liquid curable composition.

  The blending amount of the phenol resin-based curing agent in the conductive adhesive of the present embodiment varies depending on (B) the hydroxyl group equivalent of the phenol resin-based curing agent and the epoxy equivalent of the (A) glycidyl ether compound to be used. In consideration of the compatibility between the glycidyl ether compound and (B) the phenol resin-based curing agent, the viscosity as the resin composition, the heat resistance of the cured product, and the like (A) with respect to 100 parts by mass of the glycidyl ether compound (B) A phenol resin hardening | curing agent is mix | blended in the ratio of 50-150 mass parts. Preferably it is 60-140 mass parts, More preferably, it is 70-130 mass parts, More preferably, it is 80-120 mass parts.

(C) Hardening accelerator A hardening accelerator can be mix | blended with the conductive adhesive of this embodiment in order to obtain appropriate curability. This curing accelerator is not particularly limited as long as it can be used as a curing accelerator for epoxy resins, and known ones can be used, but imidazole-based, phosphine-based, or tertiary amine-based curing accelerators can be used. Is preferably used.

  Specifically, examples of the imidazole curing accelerator include imidazole compounds and derivatives thereof such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2- Examples include phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and epoxy-imidazole adduct. Examples of phosphine curing accelerators include phosphine compounds and derivatives thereof such as triphenylphosphine, triparatolylphosphine, tricyclohexylphosphine, 1,4-bisdiphenylphosphinobutane, tetraphenylphosphonium tetraphenylborate, and triphenylphosphinetriphenylborane. And tetraphenylphosphonium tetra-p-tolylborate. Tertiary amine curing accelerators include tertiary amines and derivatives thereof such as 1,8-diazabicyclo [5,4,0] undecene-7 (DBU), 1,5-diazabicyclo [4,3,0] nonene. -5 (DBN), DBU phenol salt, DBU octylate, DBU p-toluenesulfonate, DBU phenol novolac resin salt, DBN phenol novolac resin salt, DBU derivative tetraphenylborate, triethylenediamine, Examples include benzyldimethylamine and triethanolamine.

  Although the usage-amount of a hardening accelerator may be various according to the kind of phenol resin type hardening agent and hardening accelerator to be used, with respect to a total of 100 mass parts of (A) glycidyl ether compound and (B) phenol resin type hardening agent. And preferably used at a ratio of 0.1 to 10 parts by mass.

  The resin composition constituting the conductive adhesive of this embodiment is liquid at 25 ° C. itself. The solid (B) phenol resin-based curing agent and (C) curing accelerator are dissolved in the liquid (A) glycidyl ether compound to form a liquid resin composition at 25 ° C. That is, since it is liquid even if it does not use a solvent and a reactive diluent together, a solvent and a reactive diluent are not an essential component. The viscosity is not particularly limited, and may be in various viscosity ranges depending on the type of glycidyl ether compound and phenol resin curing agent to be used. From the viewpoint of ease of use, the viscosity of the resin composition is preferably 2000 Pa · s or less. . When the resin composition contains a filler, the viscosity of the resin composition before filling the filler is preferably in the range of 0.1 Pa · s to 1000 Pa · s from the viewpoint of improving the filling amount of the filler and preventing sedimentation. If the viscosity is too low, the filler is liable to settle and the dispersion state may be non-uniform. If it is too high, it is difficult to increase the filling amount of the filler. In addition, when adjusting the viscosity of a resin composition, a solvent and a reactive diluent can be used together as needed.

(D) Conductive filler The conductive filler used in the conductive adhesive of the present embodiment is at least one metal selected from the group consisting of gold, silver, copper, nickel, aluminum, and palladium, or a plurality of the metals Alloy particles or fibers, metal particles or fibers plated with gold, palladium, or silver on the metal surface, resin core balls with nickel, gold, palladium, or silver plated resin balls, carbon Alternatively, graphite particles or fibers, or metal particles, core balls, carbon or graphite particles, which are preferably coated with an insulating resin thin film, are not limited thereto, and exhibit conductivity. If it can be used and it does not damage adhesiveness (to the extent that it cannot be used as an adhesive) be able to. The shape of the conductive filler is not particularly limited, and in the case of particles, various shapes such as a spherical shape, a flat plate shape (flat shape), and a rod shape can be used. As a preferable particle diameter, the thing of the range of 5 nm-20 micrometers can be used. The particle diameter here is a number-based D50 (median diameter) particle measured by a laser diffraction / scattering method when the particle diameter is 500 nm or more, and by a dynamic light scattering method when it is less than 500 nm. Means diameter. In the case of fibers, those having a diameter of 0.1 to 3 μm, a length of 1 to 10 μm, and an aspect ratio of 5 to 100 are preferable.

  The content of the resin component (resin composition) in the conductive adhesive is determined from the printability and the conductivity of the conductive layer obtained by curing the resin composition ((A) glycidyl ether compound, (B) phenol. It is preferable that it is 5-90 mass% with respect to the sum total of a resin type hardening | curing agent and (C) hardening accelerator) and (D) conductive filler, More preferably, it is 60-85 mass%, Most preferably, it is 70. -80 mass%. When the conductive filler is uniformly dispersed in the resin composition, the content is more preferably 5 to 50% by mass, further preferably 10 to 40% by mass, and particularly preferably 15 to 30% by mass. Moreover, in order to comprise the anisotropic conductive adhesive which enables anisotropic conductive connection, it is suitable that content of a resin composition shall be 80-99.1 mass%.

  The conductive adhesive selects the type and amount of the binder resin containing the conductive filler and the above resin composition, and uses a diluent as necessary, depending on the printing method or coating method on the element, substrate, etc. And can be adjusted to an appropriate viscosity. For example, in the case of screen printing, an organic solvent having a boiling point of 200 ° C. or higher is preferably used as a diluent. Examples of such an organic solvent include diethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, and diethylene glycol monobutyl ether. Can be mentioned. Although it depends on the printing method or the coating method, the preferred viscosity of the conductive adhesive is in the range of 5 Pa · s to 500 Pa · s as measured at 25 ° C. with a rheometer.

  In addition, the conductive adhesive of the present embodiment includes a filler (for example, silica, alumina, boron nitride, aluminum nitride, etc.), a colorant (for example, for example) as long as the effects of the present invention are not impaired. Carbon black, dyes, etc.), flame retardants, ion trapping agents, antifoaming agents, leveling agents and the like may be included. Further, a silane coupling agent may be contained in order to improve the adhesion to the substrate. Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl (methyl) dimethoxysilane, 2- (2,3-epoxycyclohexyl) ethyltrimethoxysilane, 3-methacryl Examples include oxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3- (2-aminoethyl) aminopropyltrimethoxysilane.

  In addition to the above, the conductive adhesive includes, as necessary, an aluminum chelate compound such as diisopropoxy (ethyl acetoacetate) aluminum; a titanate ester such as isopropyl triisostearoyl titanate as a dispersion aid. Aliphatic polycarboxylic acid ester; unsaturated fatty acid amine salt; surfactant such as sorbitan monooleate; or polymer compound such as polyesteramine salt and polyamide. Moreover, you may mix | blend an inorganic and organic pigment, a silane coupling agent, a leveling agent, a thixotropic agent, an antifoamer, etc.

  The method for preparing the conductive adhesive according to the present embodiment is not particularly limited, and each component is mixed at a predetermined blending ratio such as a reiki machine, a propeller stirrer, a kneader, a pot mill, a three-roll mill, a rotary mixer, a twin screw mixer, and the like. By mixing means, it can be mixed and prepared uniformly. A resin composition can be prepared in advance, or (D) a conductive filler, a filler to be added as necessary, and the like can be mixed and prepared.

  The conductive adhesive can be printed or applied to the substrate by any method such as screen printing, gravure printing, dispensing, or the like. When an organic solvent is used as a diluent, the organic solvent is volatilized after printing or coating at room temperature or by heating. Next, the resin is heated and cured at 120 to 150 ° C. for 20 to 60 minutes in accordance with the type of the resin and the curing agent or curing accelerator, for example, in the case of 2-ethyl-4-methylimidazole. A conductive pattern can be formed in a necessary part.

  In this manner, an electronic device in which a semiconductor element, a solar panel, a thermoelectric element, a chip part, a discrete part, or a combination thereof is mounted on a substrate can be formed using a conductive adhesive. In addition, a conductive adhesive can be used to form an electronic device in which a film antenna, a keyboard membrane, a touch panel, and an RFID antenna are formed and connected to a substrate.

  An anisotropic conductive film can be manufactured by forming the conductive adhesive on a release film. Like conventional anisotropic conductive films, it is placed between electrodes to be connected, such as flexible substrates, rigid substrates, and electronic components, and heating, UV irradiation, etc. are performed while pressurizing between the electrodes to electrically connect the electrodes. It can be used for an anisotropic conductive connection that is mechanically connected, and this makes it possible to manufacture an electronic device including an anisotropic conductive connection. Here, the anisotropic conductive connection refers to a connection that is conductive between opposing electrodes (vertical direction) and insulative between adjacent electrodes (horizontal direction).

  Examples of the present invention will be specifically described below. In addition, the following examples are for facilitating understanding of the present invention, and the present invention is not limited to these examples.

<Measurement of epoxy equivalent>
The epoxy equivalent is determined according to JIS-K7236. A sample is weighed in an amount of 0.1 to 0.2 g, placed in an Erlenmeyer flask, and then dissolved by adding 10 mL of dichloromethane. Next, 20 mL of acetic acid is added, followed by 10 mL of tetraethylammonium bromide solution (100 g of tetraethylammonium bromide dissolved in 400 mL of acetic acid). One or two drops of crystal violet indicator are added to this solution, titrated with a 0.1 mol / L perchloric acid acetic acid solution, and an epoxy equivalent is determined according to the following formula based on the titration result.
Epoxy equivalent (g / eq) = (1000 × m) / {(V1−V0) × c}
m: Weight of sample (g)
V0: Amount of perchloric acid acetic acid solution consumed for titration to the end point in the blank test (mL)
V1: Amount of perchloric acid acetic acid solution consumed for titration to the end point (mL)
c: Concentration of perchloric acid acetic acid solution (0.1 mol / L)

<Measurement of viscosity>
The viscosities of the glycidyl ether compound and the liquid epoxy resin composition are measured using a corn plate viscometer RVDV-II + Pro manufactured by Brookfield. After 0.5 mL of the sample is placed on the sample stage, it is sandwiched between cone plates (diameter 48 mm or 24 mm, cone angle 3 °), and the viscosity is measured under the conditions of measurement temperature: 25 ° C. and rotation speed: 1 rpm. A sample with a viscosity of 1 mPa · s to 1 Pa · s uses a cone plate with a diameter of 48 mm, and a sample with a viscosity of 1 Pa · s to 2000 Pa · s uses a cone plate with a diameter of 24 mm.

<Measurement of total chlorine content>
The total chlorine amount is measured by burning and decomposing the sample at a high temperature of 800 ° C or higher in an atmosphere of oxygen gas introduced into an argon stream, absorbing the decomposed gas in ultrapure water, etc., and quantifying it by ion chromatography. By doing. The ion chromatography is composed of 861 Advanced Compact IC, Shodex SI-90 4E column manufactured by Metrohm, and is measured at a flow rate of 1.3 mL / min using 1.7 mM NaHCO ₃ /1.8 mM Na ₂ CO ₃ aqueous solution as an eluent. .

<Measurement of mass spectrum>
<GC / MS measurement>
Gas chromatography / mass spectrometry (GC / MS) by chemical ionization (CI) method is performed under the following conditions.
Apparatus: 7890A (GC part, manufactured by Agilent Technology Co., Ltd.) / JEOL JMS-Q1000GC MkII (MS part, manufactured by JEOL Ltd.)
Column: Agilent HP-5 (inner diameter 0.32 mm; length 30 m; film thickness 0.25 μm)
Column oven temperature: 50 ° C. (3 min) → [20 ° C./min]→320° C. (10 min)
Carrier gas: He
Column flow rate: 1.5 mL / min (constant flow mode)
Injection mode: Split (1:20)
Inlet temperature: 300 ° C
Injection volume: 1 μL (using an autosampler)
Transfer line temperature: 300 ° C
Ionization method: CI (chemical ionization method)
CI reaction gas: isobutane scan range: m / z 60-600
Sample preparation: 50 mg / mL (solvent is acetone)

<SEC / MS measurement>
Size exclusion chromatography / mass spectrometry (SEC / MS) by atmospheric pressure chemical ionization (APCI) method is performed under the following conditions.
1) SEC part column: ShodexGPC KF-402 × 2
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (HPLC grade), 0.3 mL / min
2) Mass spectrometer ionization method: atmospheric pressure chemical ionization method (+)
Scan range: m / z 50-2000

<Measurement of average molecular weight>
The average molecular weight of the phenol resin curing agent was measured by gel permeation chromatography (GPC). The column configuration was measured using a differential refractometer as a detector using two KF-804s manufactured by Showa Denko KK, using tetrahydrofuran as a solvent, a flow rate of 1 ml / min, a column temperature of 40 ° C., and a detector. The molecular weight was calculated in terms of polystyrene.

[Production Example 1: Synthesis of polyvalent allyl ether]
Various polyvalent allyl ethers used in Production Examples 2 to 4 described later were synthesized based on Williamson synthesis. As an example, a synthesis method of 1,4-cyclohexanedimethanol diallyl ether is described below.

  Into a 2 liter three-necked flask equipped with a stirrer and a thermometer, 144.2 g (1.00 mol) of 1,4-cyclohexanedimethanol (manufactured by Shin Nippon Rika Co., Ltd.) was placed, the inside of the reactor system was replaced with nitrogen, Add 480.0 g (6.0 mol) of an aqueous sodium oxide solution (50% by mass), heat to 40 ° C., and add 3.224 g (0.01 mol) of tetrabutylammonium bromide (Wako Pure Chemical Industries, Ltd.). did. While keeping the inside of the reaction system at about 40 ° C., 168.3 g (2.20 mol) of allyl chloride (manufactured by Kashima Chemical Co., Ltd.) was added dropwise, and after 2 hours, 72.11 g (0. 50 mol) and 84.17 g (1.10 mol) of allyl chloride were added. Thereafter, the reaction was continued while gradually raising the reaction temperature, and 25.25 g (0.33 mol) of allyl chloride was added by observing the progress of the reaction to complete the reaction. After completion of the reaction, 33.7 g of toluene was added to carry out a liquid separation treatment, and the organic layer was washed with pure water 200 mL / times until neutral, and after the liquid separation, the organic layer was evaporated to remove the solvent, allyl chloride, and the like by an evaporator. . After the solvent was distilled off, 1,4-cyclohexanedimethanol diallyl ether was obtained by precision distillation (distillation temperature: 63.9 to 67.7 ° C. (11 Pa)).

  Other polyvalent allyl ethers were also synthesized according to the above procedure.

[Production Example 2: Synthesis of 1,4-cyclohexanedimethanol diglycidyl ether (CDMDG)]
1,4-cyclohexanedimethanol diallyl ether (100 g, 0.45 mol), acetonitrile (73.2 g, 1.78 mol, manufactured by Junsei Co., Ltd.), methanol (92.9 g, 2. 90 mol, Junsei Chemical Co., Ltd.) was weighed into a 500 mL 3-diameter eggplant type flask. The temperature in the system was set to 35 ° C. using a water bath, and the pH was reached to 10.5 with a saturated aqueous potassium hydroxide solution (KOH / H ₂ O = 110 g / 100 mL). Until the end of the reaction, a saturated aqueous potassium hydroxide solution was added as needed so that the reaction temperature did not exceed 40 ° C., and the pH was controlled in the range of 10.75 to 10.25. A 45% aqueous hydrogen peroxide solution (81.6 g, 1.08 mol, manufactured by Nippon Peroxide Co., Ltd.) was added dropwise over a period of 16 hours using a 300 mL dropping funnel, and the mixture was further stirred for 10 hours to complete the reaction. When the reaction solution was measured by gas chromatography, the conversion rate of cyclohexanedimethanol diallyl ether as a substrate was 100%, the yield of cyclohexanedimethanol diglycidyl ether as diepoxy was 88.5%, monoepoxy It was confirmed that the yield of monoglycidyl ether was 2.6%.

The obtained reaction solution was distilled at a vacuum degree of 13 kPa, a flask temperature of 265 ° C., and a column temperature of 190 ° C. using a precision distillation apparatus manufactured by Daishin Kogyo Co., Ltd., so that the purity by gas chromatography was 99.5%. 1,4-cyclohexanedimethanol diglycidyl ether (CDMDG) was obtained. The viscosity of CDMDG was 34 mPa · s, and the epoxy equivalent determined by titration was 136. The total chlorine content is 5 ppm, and from the GC / MS analysis result (FIG. 1), the chlorine isotope (peak Cl in the mass spectrum) indicates that organic chlorine is not included (the contained chlorine is not derived from a compound having a carbon-chlorine bond). It was confirmed from the absence of two peaks (mass N and (N + 2) peaks based on ³⁵ and Cl ³⁷ ), where the peak intensity of N is three times the peak intensity of (N + 2).

[Production Example 3: Synthesis of glycerin triglycidyl ether (GLYG)]
Glycerol triallyl ether (50 g, 0.24 mol), acetonitrile (77 g, 1.9 mol, manufactured by Junsei Co., Ltd.), methanol (91 g, 2.8 mol, Junsei Chemical) obtained by synthesis in the same manner as in Production Example 1 above. Co., Ltd.) was charged into a 500 mL four-necked flask, and a 50% by mass aqueous potassium hydroxide solution was added to adjust the pH of the reaction solution to about 10.5. Until the end of the reaction, a saturated aqueous potassium hydroxide solution was added as needed so that the reaction temperature did not exceed 40 ° C., and the pH was controlled in the range of 10.75 to 10.25. A 35 mass% aqueous hydrogen peroxide solution (82 g, 0.8 mol) was added dropwise over 9 hours, and the mixture was further stirred for 16 hours. Then, 1 g of sodium sulfite was added to the reaction solution to stop the reaction. After the solvent was distilled off using a diaphragm pump, 500 g of ethyl acetate and an aqueous 10 mass% sodium sulfate solution were added to separate the aqueous layer and the organic layer. Thereafter, the organic layer was washed 5 times with 20 g of pure water to remove residual impurities such as sodium sulfite and by-product acetamide, and then the solvent was distilled off to obtain glycerin at a purity of 91%, a yield of 36 g, and a yield of 59%. Triglycidyl ether (GLYG) was obtained. The viscosity of GLYG was 32 mPa · s, and the epoxy equivalent determined by titration was 91. The total chlorine amount was 112 ppm, and it was confirmed in the same manner as in Production Example 2 that organic chlorine was not contained (the contained chlorine was not derived from a compound having a carbon-chlorine bond) from the GC / MS analysis result (FIG. 2).

[Production Example 4: Synthesis of pentaerythritol tetraglycidyl ether (PETG)]
Pentaerythritol tetraallyl ether (200 g, 0.67 mol), acetonitrile (220 g, 5.36 mol, manufactured by Junsei Chemical Co., Ltd.), methanol (100 g, 3.12 mol, genuine) obtained by synthesis in the same manner as in Production Example 1 above. Chemical Co., Ltd.) was charged into a 2 liter three-necked flask, and a small amount of 50% by mass potassium hydroxide aqueous solution (Wako Pure Chemical Industries, Ltd.) was added to adjust the pH in the reaction system to about 10.5. Until the end of the reaction, a saturated aqueous potassium hydroxide solution was added as needed so that the reaction temperature did not exceed 40 ° C., and the pH was controlled in the range of 10.75 to 10.25. A 45 mass% aqueous hydrogen peroxide solution (160 g, 2.12 mol, manufactured by Nippon Peroxide Co., Ltd.) was added dropwise over 18 hours. To the reaction solution, 2.11 g of sodium sulfite (manufactured by Wako Pure Chemical Industries, Ltd.) and 1000 g of toluene were added to temporarily stop the reaction, followed by stirring at room temperature for 30 minutes to separate an aqueous layer and an organic layer. Thereafter, the organic layer was washed twice with 150 g of pure water, and the solvent was distilled off to obtain a reaction mixture.

  Thereafter, acetonitrile (220 g, 5.36 mol) and methanol (100 g, 3.12 mol) were added to the reaction mixture, and a small amount of 50% by mass aqueous potassium hydroxide was added to adjust the pH of the reaction solution to about 10.5. A 45 mass% hydrogen peroxide aqueous solution (125 g, 1.65 mol) was added dropwise at a temperature of 35 ° C over 28 hours so that the internal temperature did not exceed 45 ° C. After completion of the dropwise addition, 15.9 g of sodium sulfite and 800 g of toluene were added to stop the reaction, and the mixture was stirred at room temperature for 30 minutes to separate the aqueous layer and the organic layer. Thereafter, the organic layer was washed twice with 150 g of pure water to remove residual impurities such as sodium sulfite and by-product acetamide, and the solvent was distilled off to obtain a purity of 90%, a yield of 176.04 g, and a yield of 72.4. % Pentaerythritol tetraglycidyl ether (PETG) was obtained. The viscosity of PETG was 166 mPa · s, and the epoxy equivalent determined by titration was 98. The total amount of chlorine was 636 ppm, and it was confirmed in the same manner as in Production Example 2 that organic chlorine was not contained (the contained chlorine was not derived from a compound having a carbon-chlorine bond) from the SEC / MS analysis results (FIG. 3).

[Preparation of resin composition]
The resin compositions of Examples 1 to 9 and Comparative Example 1 were prepared by mixing and dissolving each component using a 50 ° C. ultrasonic water bath with the formulation shown in Table 1. Each component used for preparation of the liquid epoxy resin composition in a table | surface is shown below.
(A) Glycidyl ether compound (A-1) 1,4-cyclohexanedimethanol diglycidyl ether obtained in Production Example 2 (CDMDG, total chlorine amount 5 ppm)
(A-2) Glycerin triglycidyl ether obtained in Production Example 3 (GLYG, total chlorine amount 112 ppm)
(A-3) Pentaerythritol tetraglycidyl ether obtained in Production Example 4 (PETG, total chlorine amount 636 ppm)
(B) Phenol resin-based curing agent (B-1) Phenol novolac resin (Showa Denko KK, Shounol (registered trademark) BRG-556, softening point 77-83 ° C., average molecular weight 1050)
(B-2) Phenol novolac resin (Showa Denko KK, Shounol (registered trademark) BRG-555, softening point 67-72 ° C., average molecular weight 800)
(B-3) Phenol novolac resin (Showa Denko KK, Shounol (registered trademark) BRG-558, softening point 93 to 98 ° C., average molecular weight 1550)
(B-4) Triphenylmethane type phenol resin (manufactured by Showa Denko KK, Shounol (registered trademark) TRI-220, softening point 83 ° C., average molecular weight 380)
(B-5) Liquid phenol novolak resin (manufactured by Showa Denko KK, patent document: synthesized based on the method disclosed in JP 2012-67253 A, average molecular weight 230)
At 25 ° C., (B-1) to (B-4) are all solid, and (B-5) is liquid.
(C) Curing accelerator (C-1) 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., Curesol (registered trademark) 2E4MZ)
(C-2) Triphenylphosphine (made by Hokuko Chemical Co., Ltd.)

<Glass transition temperature (Tg)>
Each of the resin compositions prepared in Examples 1 to 9 and Comparative Example 1 was vacuum degassed, then poured into a mold capable of producing a cured product having a thickness of 3 mm, and heated in an oven at 150 ° C. for 30 minutes. A cured plate was obtained. The obtained cured plate is cut into a 10 × 10 × 3 mm test piece, and the glass transition temperature (Tg) is measured by thermomechanical measurement (TMA). Using a TMA / SS6100 thermomechanical analyzer manufactured by SII Nanotechnology, Inc., measurement is performed under the conditions of a temperature range of −10 to 250 ° C., a heating rate of 5 ° C./min, and a load of 20.0 mN. The temperature at the intersection of two extrapolated lines drawn in the linear region before and after the inflection point based on the transition in the obtained expansion curve is defined as the glass transition temperature.

[Preparation of conductive adhesive]
Using each of the above liquid epoxy resin compositions, conductive adhesives of Examples 1 to 9 and Comparative Example 1 were prepared with the formulations shown in Table 1. The conductive filler used for the preparation of the conductive adhesive in the table is shown below.
(D) Conductive filler (D-1) silver particles (manufactured by Fukuda Metal Foil Industry Co., Ltd., AgC-GS, average particle size of 5 to 10 μm (catalog value))
(D-2) Silver particles (manufactured by Fukuda Metal Foil Industry Co., Ltd., AgC-239, average particle diameter of 2 to 15 μm (catalog value))
(D-3) Silver particles (Tokusen Kogyo Co., Ltd., N300, average particle size 0.3 μm)

  The method for preparing the conductive adhesive is as follows. That is, the liquid epoxy resin composition and the conductive filler were mixed in a disposable cup and mixed well with a spatula until uniform. The mixture was further mixed for 1 minute at Rotation / Revolution = 800/2000 rpm with a rotation / revolution mixer Awatori Nertaro ARE-310 (manufactured by Sinky Co., Ltd.) to prepare a conductive adhesive.

<Production of circuit sample>
A circuit sample was produced using the conductive adhesive obtained as described above. The configuration of the fabricated circuit sample is shown in FIG. In FIG. 4, the conductive adhesive 12 is stencil-printed on the copper surface of the copper-clad glass epoxy substrate 14 using a metal mask having a thickness of 75 μm (the pattern shape is the electrodes and copper wirings on both ends of the chip resistor 16). (Width: 0.5 ± 0.2 mm) 18a and 18b). This is tin-plated (thickness 2 μm) to 2012 size (specific shapes are L (length), W (width), d (electrode width), t (thickness) (unit: mm) = 5.0 ± 0.2, 2.5 ± 0.2, 0.5 ± 0.2, 0.5 ± 0.2) chip resistor 16 is pressed by hand and heated at 150 ° C. for 30 minutes to bond By curing the agent, the chip resistor 16 was connected to the circuit board 14 to produce the circuit sample 10.

<Shear strength>
The shear strength was evaluated using a circuit sample 10 using a bond tester (manufactured by DAGE Series 4000 Dage (UK), purchased from Tage Japan Co., Ltd.). The number of samples was 5, and the average value was obtained.

  Specifically, as shown in FIG. 5, in the circuit sample 10 in which the chip resistor 16 is bonded to the substrate 14 with the conductive adhesive 12 at room temperature, the shear tool 20 to which the load sensor is attached is connected to the chip resistor 16. Pressing in the horizontal direction in contact with the L side (left side of the figure), the strength when the joint surface between the chip resistor 16 and the substrate 14 is broken is measured. The share tool 20 descends in the direction of arrow A to the substrate surface (FIG. 5A), and after detecting the substrate position, it rises in the direction of arrow B to a preset height h (FIG. 5B). Thereafter, the chip resistor 16 is pushed in the horizontal direction at an arbitrary speed (FIG. 5C), and the load when the joint surface is broken (FIG. 5D) is measured.

<Initial resistance>
The connection resistance (electrical resistance between the copper wirings 18a and 18b) (Ω) of the circuit sample 10 was measured with a tester (Model: PC500a RS-232C manufactured by SANWA). The number of samples was 5, and the average value was obtained.

<High temperature and high humidity test>
The sample for which the initial resistance was measured was stored in an environment at a temperature of 85 ° C. and a humidity of 85% using a constant temperature and high humidity device TH402A manufactured by Enomoto Kasei Co., Ltd., and the change in resistance was measured over time. The time required for the initial resistance to be 10 times from the measurement results was determined and shown in Table 1.

<High temperature test>
The sample whose initial resistance was measured was stored in a 120 ° C. environment using a constant temperature dryer DX302 manufactured by Yamato Scientific Co., Ltd., and the change in resistance was measured over time. Table 1 shows the time required for the initial resistance to double from the measurement result.

  As shown in Table 1, when Tg (glass transition temperature) of the cured product obtained by heating the resin composition at 150 ° C. for 30 minutes is compared, Examples 1 to 10 using solid phenol are liquid phenols. A cured product having higher heat resistance than that of Comparative Example 1 used is obtained. As a result of blending a conductive filler therein to form a conductive adhesive, a conductive adhesive having a higher shear strength and a higher adhesive strength was obtained in any of the Examples. Also, in the high-temperature and high-humidity test and the high-temperature test, since the degree of increase in the resistance value was kept low, it was confirmed that high heat resistance was maintained as the conductive adhesive.

  10 circuit sample, 12 conductive adhesive, 14 substrate, 16 chip resistor, 18a, 18b copper wiring, 20 share tool.

Claims (13)

  (A) a glycidyl ether compound that is liquid at 25 ° C. and substantially free of carbon-chlorine bonds, (B) a phenol resin curing agent having an average molecular weight of 350 or more that is solid at 25 ° C., and (C) It contains a curing accelerator and (D) a conductive filler and contains 50 to 150 parts by mass of (B) a phenol resin curing agent with respect to 100 parts by mass of the (A) glycidyl ether compound. adhesive.   The conductive adhesive according to claim 1, wherein the (A) glycidyl ether compound is a polyvalent glycidyl ether of an aliphatic polyhydric alcohol having 3 to 30 carbon atoms.   The conductive adhesive according to claim 1 or 2, wherein the (A) glycidyl ether compound is obtained by reacting an allyl group carbon-carbon double bond of an allyl ether compound with an oxidizing agent.   The conductive adhesive according to any one of claims 1 to 3, wherein the viscosity of the (A) glycidyl ether compound at 25 ° C is 1 mPa · s to 1000 mPa · s.   The (A) glycidyl ether compound is 1,4-cyclohexanedimethanol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, ditrimethylolpropane tetraglycidyl ether, diglycerin tetraglycidyl ether. The conductive adhesive according to any one of claims 1 to 4, comprising at least one selected from the group consisting of: dipentaerythritol hexaglycidyl ether, and sorbitol hexaglycidyl ether.   The said (B) phenol resin hardening | curing agent contains at least 1 sort (s) selected from the group which consists of a phenol novolak resin, a cresol novolak resin, a triphenylmethane type phenol resin, and a dicyclopentadiene modified phenol resin. The conductive adhesive according to any one of 5.   The conductive adhesive according to any one of claims 1 to 6, which does not contain a solvent and a reactive diluent.   The said (C) hardening accelerator is at least 1 sort (s) selected from the group which consists of an imidazole compound and its derivative (s), a phosphine compound and its derivative (s), and a tertiary amine and its derivative (s). The conductive adhesive according to Item.   Any one of Claims 1-8 which contain 0.1-10 mass parts of said (C) hardening accelerators with respect to a total of 100 mass parts of said (A) glycidyl ether compound and (B) phenol resin type hardening | curing agent. The conductive adhesive according to one item.   The (D) conductive filler is at least one metal selected from the group consisting of gold, silver, copper, nickel, aluminum, palladium, or particles or fibers made of an alloy of the plurality of metals, gold on the metal surface, Metal particles or fibers plated with either palladium or silver, resin core balls plated with either nickel, gold, palladium, or silver on resin balls, carbon or graphite particles or fibers, or the metal particles or cores The conductive adhesive according to any one of claims 1 to 9, wherein the surface of particles of balls, carbon, or graphite is coated with an insulating resin thin film.   The total content of the (A) glycidyl ether compound, the (B) phenol resin-based curing agent, and the (C) curing accelerator in the conductive adhesive is 5 to 90% by mass. The conductive adhesive according to claim 1.   The conductive adhesive according to any one of claims 1 to 11, wherein a semiconductor element, a solar panel, a thermoelectric element, a chip part, a discrete part, or a combination thereof is mounted on a substrate. Electronic equipment.   An electronic apparatus comprising: a film antenna, a keyboard membrane, a touch panel, a wiring for an RFID antenna, and a connection to a substrate using the conductive adhesive according to any one of claims 1 to 11.

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