JP2019112566A - Conductive adhesive - Google Patents

Abstract

To provide a conductive adhesive good in sharpness of the conductive adhesive even when discharged by using a dispenser, having proper thixotropy after discharge, and capable of being cured at low temperature.SOLUTION: A conductive adhesive is a conductive adhesive capable of application by using a dispenser at high speed, and being cured at low temperature, and having a Structural Viscosity Index (SVI) value of 2.5 to 6, and viscosity at 23°C of 1 Pa s to 20 Pa s.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive adhesive. In particular, the present invention relates to a conductive adhesive which is easy to discharge from a dispenser and has a good sharpness.

  A conductive adhesive composition comprising (A) a conductive particle composed of a metal having a melting point of 210 ° C. or less, (B) a thermosetting resin and (C) a flux activator, The viscosity of the adhesive composition is 5 to 30 Pa · s, and the content of the (A) conductive particles is 70 to 90% by mass with respect to the total amount of the conductive adhesive composition, and the non-contact type dispenser Conductive adhesive compositions for use are known (see, for example, Patent Document 1). According to the conductive adhesive composition which concerns on patent document 1, it can apply with a non-contact-type dispenser.

Patent No. 6144048

  However, in the case of the conductive adhesive composition described in Patent Document 1, when the conductive adhesive composition is continuously discharged using a dispenser, the conductive adhesive composition may be softened and the predetermined It has not been solved about the point made compatible with keeping the state where the electroconductive adhesive composition discharged on the base material was discharged substantially.

  By the way, in recent years, in order to form a circuit on a flexible substrate, application of a conductive adhesive composition using a dispenser is required. However, the flexible substrate has a substrate which is weak to heat, and the conductive adhesive composition described in, for example, Patent Document 1 requires heating at a high temperature of 140 ° C. or higher for curing. , Could not be applied to heat-sensitive substrates.

  Therefore, it is an object of the present invention to provide a conductive adhesive which is well-knitted even when discharged using a dispenser, and which has the ability to maintain the intended shape after discharge and which can be cured at a low temperature Purpose is to provide an adhesive.

  In order to achieve the above object, the present invention is a conductive adhesive which can be applied at high speed using a dispenser and which can be cured at a low temperature, and has a Structural Viscosity Index (SVI) value of 2.5. A conductive adhesive having a viscosity of 6 Pa or more and a viscosity at 23 ° C. of 1 Pa · s or more and 20 Pa · s or less is provided.

  In the conductive adhesive, the conductive adhesive preferably contains (A) a crosslinkable silicon group-containing organic polymer, (B) a conductive filler, and (C) a thixotropic agent.

  In the above conductive adhesive, the main chain skeleton of the (A) crosslinkable silicon group-containing organic polymer is composed of a polyoxyalkylene polymer, a saturated hydrocarbon polymer, and a (meth) acrylate polymer. (B) The conductive filler comprises (b1) a first silver powder and a silver-plated powder, and (b2) a second silver powder and a silver-plated powder, and (C) The thixotropic agent is preferably a silica-based compound or an amide wax-based compound.

In the above conductive adhesive, the specific surface area of the (b1) first silver powder and silver plated powder is 0.5 m ² / g or more and less than 2.0 m ² / g, and the tap density is 2.5 to 6.0 g / cm ³ (B2) The specific surface area of the second silver powder and the silver-plated powder is 2.0 m ² / g or more and 7.0 m ² / g or less, and the tap density is 1.0 to 3.0 g / cm ³ ( The mixing ratio [(b1) / (b2)] of b1) and (b2) is 1/10 or more and 10/1 or less by mass ratio, and the silica-based compound which is the (C) thixotropy-imparting agent has a surface treatment It may be one or more silicas selected from the group consisting of hydrophobic silica hydrophobized by an agent, and hydrophilic silica which is fumed silica having silanol groups on the surface.

  In the above conductive adhesive, the (B) conductive filler is 65% by mass or more and 85% by mass or less of the total content, and the surface treatment agent is dimethyldichlorosilane, hexamethyldisilazane, (meth) acrylsilane, It may be one or more selected from the group consisting of octylsilane and aminosilane.

  In the conductive adhesive, the conductive adhesive preferably further contains a diluent.

  Moreover, in order to achieve the said objective, this invention provides the product which has a hardened | cured material of the electroconductive adhesive as described in any one of said.

  Moreover, in order to achieve the said objective, this invention apply | coats the electroconductive adhesive as described in any one of said to the predetermined location of a base material, and on the electroconductive adhesive on a base material A device manufacturing method is provided comprising: a mounting step of mounting a device; and a heating step of heating a substrate having the device mounted on the substrate via a conductive adhesive.

  According to the conductive adhesive according to the present invention, the conductive adhesive has a good sharpness even when discharged using a dispenser, and has the ability to maintain the intended shape after discharge, and at low temperature. A curable conductive adhesive can be provided. In addition, since the conductive adhesive can be discharged from the dispenser at a high speed, the time required for forming the conductive pattern can be shortened.

It is a figure of the test film used for the dispensing precision test about the electroconductive adhesive which concerns on Example 1 and Comparative Example 1. FIG.

[Overview of conductive adhesive]
When a predetermined electronic element or the like is mounted on a predetermined base having a conductive pattern (wiring pattern), the electronic element or the like is fixed to the conductive pattern via a conductive adhesive. In the case of mounting a plurality of electronic elements and the like on a base material and in the case of manufacturing a plurality of base materials, it is required to improve the mounting speed of the electronic elements and the like from the viewpoint of reduction in manufacturing cost. In this case, the mounting speed of the electronic element or the like can be improved by discharging and applying the conductive adhesive successively one after another at high speed using a dispenser.

  Here, when the conductive adhesive does not have an appropriate viscosity (e.g., when the viscosity is too high, etc.), the conductive adhesive may not be able to be discharged from the nozzle of the dispenser. Also, the conductive adhesive is discharged to a certain position (first position) on the substrate using a dispenser, and then the nozzle of the dispenser is moved to the position (second position) where the conductive adhesive should be discharged. Then, the conductive adhesive may not be well-knitted, and the conductive adhesive at the first position and the conductive adhesive at the second position may be connected by the conductive adhesive. Furthermore, if the SVI value of the conductive adhesive is not properly adjusted from the viewpoint of improving the shrinkage of the conductive adhesive, the conductive adhesive discharged onto the substrate spreads on the substrate and is adjacent It may come in contact with other conductive adhesives. These challenges can occur more prominently if the dispenser is a high speed dispenser. For example, when a conductive adhesive having a viscosity exceeding 100 Pa · s is used as the conductive adhesive, using a dispenser having a normal nozzle (needle type), the conductive adhesive is applied to one point. It takes about 5 seconds, and in some cases, the conductive adhesive may not be discharged from the nozzle. In addition, the high-speed dispenser in this invention is a dispenser which can discharge a composition, for example at the speed of 1 shot 1 second or less.

  Therefore, as a result of examining the characteristics of the conductive adhesive from various points of view, the present inventors found that the structural viscosity index (SVI) value related not only to the viscosity of the conductive adhesive but also to the thixotropy of the conductive adhesive. It has been found that setting the balance with the viscosity in an appropriate range is effective in terms of simultaneously solving the above-mentioned multiple problems. In the present invention, the viscosity can be measured at a rotation speed of 20 r / min under a temperature condition of 23 ° C. in accordance with JIS K 6833-1 using a B-type viscometer. The SVI value is measured using a B-type viscometer according to JIS K6833-1, under the temperature condition of 23 ° C, viscosity A at high rotational speed (rotation number 2 r / min) and high rotational speed It is a value represented by the ratio (A / B) to the viscosity B at the time of (rotational speed 20 r / min).

  That is, the conductive adhesive according to the present invention is a conductive adhesive which can be used in a high-speed dispenser and can be cured at a low temperature, and has a Structural Viscosity Index (SVI) value of 2.5 or more and 6 or less. It is an electroconductive adhesive whose viscosity in 23 degreeC is 1 Pa.s or more and 20 Pa.s or less. The SVI value of the conductive adhesive according to the present invention is more preferably 3 or more and 5 or less, and the viscosity is more preferably 1 Pa · s or more and 15 Pa · s or less. Further, “low temperature” is, for example, a temperature of about 80 ° C., but at least a temperature lower than a temperature (about 250 ° C.) in a reflow furnace used for solder or the like.

  The conductive adhesive is not particularly limited as long as the viscosity and the SVI value satisfy the above-mentioned ranges, and a conventionally known conductive adhesive can be used. As a binder resin of the conductive adhesive, for example, a binder resin of moisture curing type, water dispersion type, solvent evaporation type, or heat curing type can be used. Examples of the moisture-curable binder resin include silicone resins and modified silicone resins. Examples of the water-dispersible binder resin include PVA resins, urethane resins, acrylic resins, and the like. A system, an acrylic resin system, etc. are mentioned, An epoxy resin etc. can be mentioned as a binder resin of heat-hardening type.

  More specifically, the conductive adhesive of the present invention is a moisture-curable type containing (A) a crosslinkable silicon group-containing organic polymer, (B) a conductive filler, and (C) a thixotropic agent. It is preferable that it is a modified silicone type conductive adhesive. The main chain skeleton of the crosslinkable silicon group-containing organic polymer (A) is selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers, and (meth) acrylic acid ester polymers It is preferable that it is 1 or more types, and it is preferable that (B) electroconductive filler contains (b1) 1st silver powder and silver plating powder, and (b2) 2nd silver powder and silver plating powder. The (C) thixotropic agent is preferably a silica-based compound or an amide wax-based compound. In addition, the silica-based compound (C) which is a thixotropy-imparting agent is selected from the group consisting of hydrophobic silica hydrophobized by a surface treatment agent and hydrophilic silica which is fumed silica having silanol groups on the surface. More preferably, it is one or more kinds of silica.

[(A) Crosslinkable Silicon Group-Containing Organic Polymer]
The crosslinkable silicon group-containing organic polymer (A) is not particularly limited as long as it is an organic polymer having a crosslinkable silicon group, and examples thereof include modified silicone resins (hereinafter, (A) crosslinkable silicon group A contained organic polymer may be called "(A) component."

  The crosslinkable silicon group of the crosslinkable silicon group-containing organic polymer is a group which has a hydroxyl group or a hydrolyzable group bonded to a silicon atom and can be crosslinked by forming a siloxane bond. As the crosslinkable silicon group, for example, a group represented by the general formula (1) is preferable.

In Formula (1), R ¹ represents an organic group. R ¹ is preferably a hydrocarbon group having 1 to 20 carbon atoms. Among these, R ¹ is particularly preferably a methyl group. R ¹ may have a substituent. X represents a hydroxyl group or a hydrolyzable group, and when two or more X are present, a plurality of X may be the same or different. a is an integer of 1, 2 or 3; From the viewpoint of curability, a is preferably 2 or more, and more preferably a is 3.

  The hydrolyzable group represented by X is not particularly limited as long as it is other than F atom. For example, an alkoxy group, an acyloxy group, a ketoxime group, an aminooxy group, an alkenyloxy group and the like can be mentioned. Among these, an alkoxy group is preferable in view of mild hydrolyzability and easy handling. Among the alkoxy groups, a group having a smaller number of carbon atoms is more reactive, and the reactivity becomes lower as the number of carbon atoms increases, as in the order of methoxy group> ethoxy group> propoxy group. Although it can be selected according to the purpose and application, usually, a methoxy group or an ethoxy group is used.

As the crosslinkable silicon group, for example, trialkoxysilyl groups such as trimethoxysilyl group and triethoxysilyl group, -Si (OR) ₃ , dialkoxysilyl groups such as methyldimethoxysilyl group and methyldiethoxysilyl group,- SiR ¹ (OR) ₂ is mentioned. Here, R is an alkyl group such as a methyl group or an ethyl group. The crosslinkable silicon group may be used alone or in combination of two or more. The crosslinkable silicon group may be bonded to the main chain or side chain, or to either. In the crosslinkable silicon group-containing organic polymer, the crosslinkable silicon group is preferably present in an average of 1.0 or more and 5 or less in one molecule of the crosslinkable silicon group-containing organic polymer, and 1.1 to 3 More preferably, one is present.

  Specific examples of the main chain skeleton of the crosslinkable silicon group-containing organic polymer include polyoxyalkylene polymers such as polyoxypropylene, polyoxytetramethylene and polyoxyethylene-polyoxypropylene copolymer; ethylene- Hydrocarbon-based polymers such as propylene-based copolymers, polyisobutylenes, polyisoprenes, polybutadienes and hydrogenated polyolefin-based polymers obtained by hydrogenating these polyolefin-based polymers; Dibasic acids such as adipic acid and glycols Polyester polymers obtained by ring-opening polymerization of lactones, or (meth) acrylic acid ester polymers obtained by radical polymerization of monomers such as ethyl (meth) acrylate and butyl (meth) acrylate (Meth) acrylic acid ester monomers, vinyl acetate, acrylonitrile Vinyl polymers obtained by radical polymerization of monomers such as styrene; graft polymers obtained by polymerizing vinyl monomers in organic polymers; polysulfide polymers; polyamide polymers; polycarbonate polymers; Examples include diallyl phthalate polymers and the like. These skeletons may be contained alone in the crosslinkable silicon group-containing organic polymer, or two or more types may be contained in blocks or randomly.

  Furthermore, saturated hydrocarbon polymers such as polyisobutylene, hydrogenated polyisoprene and hydrogenated polybutadiene, polyoxyalkylene polymers, and (meth) acrylate polymers can be obtained with a relatively low glass transition temperature. The cured product is preferable because it is excellent in cold resistance. In addition, polyoxyalkylene polymers and (meth) acrylic acid ester polymers are particularly preferable because they have high moisture permeability and are excellent in deep-part curability when made into a one-pack composition.

  In addition, the glass transition temperature is relatively low, and the obtained adhesive is excellent in cold resistance, and contains no low molecular weight cyclic siloxane, is free from siloxane, and from the viewpoint of preventing contact failure, the main chain skeleton It is preferable to contain at least one selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers, and (meth) acrylate polymers.

  Various monomers can be used as the (meth) acrylic acid ester-based monomer that constitutes the main chain of the (meth) acrylic acid ester-based polymer. For example, (meth) acrylic acid type monomers; (meth) acrylic acid alkyl ester type monomers such as (meth) acrylic acid n-butyl, (meth) acrylic acid stearyl etc; alicyclic (meth) acrylic acid ester type monomers; Group (meth) acrylic acid ester monomers; (meth) acrylic acid ester monomers such as (meth) acrylic acid 2-methoxyethyl; silyl group-containing (meth) acrylic acids such as γ- (methacryloyloxypropyl) trimethoxysilane An ester monomer etc. are mentioned.

  In the (meth) acrylic acid ester-based polymer, the following vinyl-based monomers can be copolymerized together with the (meth) acrylic acid ester-based monomer. Examples of vinyl monomers include styrene, maleic anhydride, vinyl acetate and the like. Moreover, you may contain acrylic acid and glycidyl acrylate other than these as a monomer unit (Hereafter, it is also called other monomer units.).

  These may be used alone or in combination of two or more. From the viewpoint of physical properties and the like of the product, a polymer comprising a (meth) acrylic acid-based monomer is preferred. Moreover, the (meth) acrylic-ester type polymer which used together the other (meth) acrylic acid monomer as needed using 1 type, or 2 or more types of (meth) acrylic-acid alkylester monomers is more preferable. Furthermore, the number of silicon groups in the (meth) acrylic acid ester-based polymer can be controlled by using a silyl group-containing (meth) acrylic acid ester-based monomer in combination. Particularly preferred is a methacrylic acid ester-based polymer comprising a methacrylic acid ester monomer because of its good adhesion. In order to lower the viscosity and impart flexibility, it is preferable to appropriately use an acrylic ester monomer. In the present invention, (meth) acrylic acid represents acrylic acid and / or methacrylic acid.

  For example, a radical polymerization method using a radical polymerization reaction can be used as a method for producing the (meth) acrylate polymer. As a radical polymerization method, a radical polymerization method (free radical polymerization method) in which a predetermined monomer unit is copolymerized using a polymerization initiator, or a controlled radical capable of introducing a reactive silyl group at a controlled position such as an end. The polymerization method is mentioned. However, the polymer obtained by the free radical polymerization method using an azo compound, a peroxide or the like as a polymerization initiator generally has a molecular weight distribution value as large as 2 or more, and the viscosity becomes high. Therefore, in the case of obtaining a (meth) acrylic acid ester polymer having a narrow molecular weight distribution and a low viscosity (meth) acrylic acid ester polymer and having a crosslinkable functional group at the molecular chain terminal at a high rate. Preferably, controlled radical polymerization is used.

  As the controlled radical polymerization method, a free radical polymerization method or a living radical polymerization method using a chain transfer agent having a specific functional group may be mentioned. It is preferable to adopt a living radical polymerization method such as atom transfer radical polymerization (ATRP). In addition, a main chain skeleton is a (meth) acrylic acid ester type polymer, and the one part is the reactivity as a reaction which synthesizes a polymer which is a telechelic polymer (henceforth "pseudo telechelic polymer"). A reaction using a thiol compound having a silyl group, a reaction using a thiol compound having a reactive silyl group, and a metallocene compound can be mentioned.

  These crosslinkable silicon group-containing organic polymers may be used alone or in combination of two or more. Specifically, a group comprising a polyoxyalkylene polymer having a crosslinkable silicon group, a saturated hydrocarbon polymer having a crosslinkable silicon group, and a (meth) acrylic acid ester polymer having a crosslinkable silicon group The crosslinkable silicon group-containing organic polymer which blended 2 or more types selected from can be used. In particular, a crosslinkable silicon group-containing organic polymer in which a polyoxyalkylene polymer having a crosslinkable silicon group and a (meth) acrylic acid ester polymer having a crosslinkable silicon group are blended has excellent properties.

There are various methods for producing a crosslinkable silicon group-containing organic polymer in which a polyoxyalkylene polymer having a crosslinkable silicon group and a (meth) acrylate polymer having a crosslinkable silicon group are blended. It can be mentioned. For example, it has a crosslinkable silicon group, and the molecular chain substantially has a general formula (2):
_{^{-CH 2 -C (R 2) (}} COOR 3) - ··· (2)
(Wherein, R ² represents a hydrogen atom or a methyl group, and R ³ represents an alkyl group having 1 to 6 carbon atoms. Preferably, an alkyl group having 1 to 2 carbon atoms is mentioned. In addition, R ³ is an individual). And (meth) acrylic acid ester monomer unit represented by the formula (3):
_{^{-CH 2 -C (R 2) (}} COOR 4) - ··· (3)
(Wherein, R ² is the same as above, and R ⁴ is an alkyl group having 8 or more carbon atoms. Preferably, long-chain alkyl groups having 8 to 20 carbon atoms such as 2-ethylhexyl group, stearyl group, etc.) In addition, R ⁴ may be a single one, or two or more types may be mixed.) A copolymer comprising a (meth) acrylic acid ester monomer unit represented by The method of blending and manufacturing an oxyalkylene type polymer is mentioned.

  The molecular chain of the (meth) acrylic acid ester copolymer substantially consists of the monomer units of the formulas (2) and (3). Here, "substantially" means that the total of the monomer units of the formulas (2) and (3) present in the copolymer exceeds 50% by mass. The total of the monomer units of the formulas (2) and (3) is preferably 70% by mass or more. The mass ratio of the monomer unit of formula (2) to the monomer unit of formula (3) is preferably 95: 5 to 40:60, and more preferably 90:10 to 60:40. .

  The number average molecular weight of the (meth) acrylate polymer is preferably 600 or more and 10,000 or less, more preferably 1,000 or more and 5,000 or less, and still more preferably 1,000 or more and 4,500 or less. By setting the number average molecular weight in this range, the compatibility with the polyoxyalkylene polymer having a crosslinkable silicon group is improved. The (meth) acrylate polymers may be used alone or in combination of two or more. There are no particular restrictions on the compounding ratio of the crosslinkable silicon group-containing polyoxyalkylene polymer to the crosslinkable silicon group-containing (meth) acrylate polymer, but the (meth) acrylate polymer and the poly It is preferable that a (meth) acrylic-ester type polymer exists in the range of 10-60 mass parts with respect to a total of 100 mass parts with an oxyalkylene type polymer, The inside of the range which is 20-50 mass parts is more preferable The range of 25 to 45 parts by mass is more preferable. When the amount of the (meth) acrylic acid ester-based polymer is more than 60 parts by mass, the viscosity becomes high and the workability is deteriorated.

  Furthermore, in the present invention, an organic polymer in which a saturated hydrocarbon polymer having a crosslinkable silicon group and a (meth) acrylic acid ester copolymer having a crosslinkable silicon group can be used. As another method of producing an organic polymer obtained by blending a (meth) acrylic acid ester copolymer having a crosslinkable silicon group, in the presence of an organic polymer having a crosslinkable silicon group (Meta ) A method of polymerizing acrylic acid ester type monomer can be used.

A polymer having a main chain skeleton of an oxyalkylene polymer and having a functional group such as a hydrolyzable group at its end (hereinafter referred to as "polyoxyalkylene polymer") is essentially represented by the general formula (4) Polymers having repeating units.
-R ⁵ -O- (4)
In the general formula (4), R ⁵ is a linear or branched alkylene group having 1 to 14 carbon atoms, preferably a linear or branched alkylene group having 2 to 4 carbon atoms.

Specific examples of the repeating unit represented by the general formula _{(4), -CH 2 CH 2} O -, - CH 2 CH (CH 3) O -, - CH 2 CH 2 CH 2 CH 2 O- and the like . The main chain skeleton of the polyoxyalkylene polymer may consist of only one type of repeating unit, or may consist of two or more types of repeating units. In particular, a main chain skeleton composed of a polymer containing oxypropylene as a main component is preferable.

  The molecular weight of the polyoxyalkylene polymer having a crosslinkable silicon group is preferably a high molecular weight in order to reduce the tensile modulus, which is the initial tensile properties of the cured product, and increase the elongation at break. In the present invention, the lower limit of the number average molecular weight of the polyoxyalkylene polymer is preferably 15,000, more preferably 18,000 or more, and more preferably 20,000 or more. The upper limit of the number average molecular weight is preferably 50,000, more preferably 40,000. In addition, the number average molecular weight concerning this invention is a polystyrene conversion molecular weight by gel permeation chromatography. If the number average molecular weight is less than 15,000, the tensile modulus and the elongation at break may not be sufficient, and if it exceeds 50,000, the viscosity of the composition may be increased to lower the workability.

  When the content of the crosslinkable silicon group in the polyoxyalkylene polymer is appropriately reduced, the crosslink density in the cured product is reduced, so that the cured product becomes softer at the initial stage, and the modulus characteristics become smaller and the elongation at break becomes The characteristics are increased. In the polyoxyalkylene polymer, the crosslinkable silicon group is preferably present in an average of 1.2 or more and 2.8 or less in one polymer molecule, and is 1.3 or more and 2.6 or less. More preferably, the number is 1.4 or more and 2.4 or less. If the number of crosslinkable silicon groups contained in the molecule is less than one, the curability will be insufficient, and if too large, the network structure will be too dense to show good mechanical properties. And in the case of a bifunctional polymer whose main chain skeleton is a straight chain, the crosslinkable silicon group of the polymer is present in an average of 1.2 or more and less than 1.9 in one polymer molecule. Is more preferably 1.25 or more and 1.8 or less, still more preferably 1.3 or more and less than 1.7.

  The polyoxyalkylene polymer having a crosslinkable silicon group may be linear or branched. From the viewpoint of reducing the tensile modulus, the polyoxyalkylene polymer having a crosslinkable silicon group is preferably a linear polymer.

  Examples of the synthesis method of the polyoxyalkylene polymer include, but not particularly limited to, a polymerization method by an alkali catalyst such as KOH and a polymerization method by a double metal cyanide complex catalyst. According to a double metal cyanide complex catalyst polymerization method, a polyoxyalkylene type having a high molecular weight with a number average molecular weight of 6,000 or more and Mw (weight average molecular weight) / Mn (number average molecular weight) of 1.6 or less and a narrow molecular weight distribution Polymers can be obtained.

  The main chain skeleton of the polyoxyalkylene polymer may contain other components such as a urethane bond component. Examples of the urethane bond component include aromatic polyisocyanates such as toluene diisocyanate; and components obtained from the reaction of aliphatic polyisocyanates such as isophorone diisocyanate with polyoxyalkylene polymers having a hydroxyl group. .

  A polyoxyalkylene polymer having a functional group such as an unsaturated group, a hydroxyl group, an epoxy group, or an isocyanate group in a molecule, and a compound having a functional group having reactivity with this functional group and a crosslinkable silicon group The crosslinkable silicon group can be introduced into the polyoxyalkylene polymer by reacting (hereinafter referred to as a polymer reaction method).

  As an example of the polymer reaction method, a hydrosilane having a crosslinkable silicon group or a mercapto compound having a crosslinkable silicon group is allowed to act on an unsaturated group-containing polyoxyalkylene polymer to hydrosilylate or mercapitize, and the crosslinkable silicon group The method of obtaining the polyoxyalkylene type polymer which has these can be mentioned. An unsaturated group-containing polyoxyalkylene polymer is obtained by reacting an organic polymer having a functional group such as a hydroxyl group with an organic compound having an active group and an unsaturated group having reactivity with the functional group. be able to.

  Further, as another example of the polymer reaction method, a method of reacting a polyoxyalkylene polymer having a hydroxyl group at an end with an isocyanate group and a compound having a crosslinkable silicon group, a polyoxy having an isocyanate group at an end A method of reacting an alkylene polymer with a compound having an active hydrogen group such as a hydroxyl group or an amino group and a crosslinkable silicon group can be mentioned. When an isocyanate compound is used, a polyoxyalkylene polymer having a crosslinkable silicon group can be easily obtained.

  The polyoxyalkylene polymer having a crosslinkable silicon group may be used alone or in combination of two or more.

[(B) conductive filler]
(B) The conductive filler is formed using a material having electrical conductivity. As the conductive filler, for example, silver powder, copper powder, nickel powder, aluminum powder, and silver plated powder thereof, metal powder such as silver coated glass, silver coated silica, silver coated plastic, etc .; zinc oxide, titanium oxide, ITO , ATO, carbon black and the like. From the viewpoint of reducing the volume resistivity, the conductive filler is preferably silver powder or silver plating powder, and from the viewpoint of conductivity reliability and cost, it is more preferable to use silver powder and silver plating powder in combination (below, (B A conductive filler may be called "(B) component".

  (B) As the shape of the conductive filler, various shapes (for example, granular, spherical, elliptical, cylindrical, flake, flat, or agglomerates) can be adopted. The conductive filler can also have a somewhat rough or jagged surface. The particle shape, size, and / or hardness of the conductive filler can be combined and used in the conductive adhesive of the present invention. In addition, in order to further improve the conductivity of the cured product of the conductive adhesive, it is also possible to combine a plurality of conductive fillers having different particle shapes, sizes and / or hardness of (B) conductive filler. it can. In addition, the conductive filler to be combined is not limited to two types, and may be three or more types. In the present invention, it is preferable to use a flaky conductive filler and a conductive filler such as particles in combination.

  Here, the flake shape includes a flat shape, a flaky shape, or a scaly shape, and includes a shape obtained by crushing silver powder having a three-dimensional shape such as a spherical shape or a massive shape in one direction. Moreover, a granular form means the shape of all the electroconductive fillers which do not have flake shape. For example, as the granular form, there may be mentioned a shape in which powder is aggregated into a bunch of grapes, a spherical shape, a substantially spherical shape, a massive shape, a dendritic shape, or a mixture of silver powder having these shapes.

  Moreover, when using silver powder and silver plating powder as (B) electroconductive filler, this electroconductive filler can be manufactured by various methods. For example, when flake-like silver powder is used as a conductive filler, it is manufactured by mechanically pulverizing silver powder such as spherical silver powder, massive silver powder, and / or granular silver powder using an apparatus such as a jet mill, roll mill or ball mill. it can. When granular silver powder is used as a conductive filler, it can be produced by an electrolytic method, a pulverizing method, a heat treatment method, an atomizing method, a reduction method or the like. Among these, the reduction method is preferable because a powder with a low tap density can be easily obtained by controlling the reduction method.

  (B) As silver powder and silver plating powder used for a conductive filler, well-known silver powder and silver plating powder can be used widely. The silver powder and the silver-plated powder preferably include (b1) the first silver powder and the silver-plated powder and (b2) the second silver powder and the silver-plated powder, which have predetermined specific surface areas and tap densities, respectively. The mixing ratio [(b1) / (b2)] of (b1) and (b2) is 1/10 or more and 10/1 or less in mass ratio, preferably 1⁄4 or more and 4/1 or less, and 3/2 More than 4/1 is more preferable. Moreover, in the component (b1), the mixing ratio of the first silver powder and the silver plating powder is 1/10 or more and 10/1 or less, and in the component (b2), the mixing ratio of the second silver powder and the silver plating powder Is 1/10 or more and 10/1 or less.

(B1) a specific surface area of the first silver powder and silver-plated powder preferably is less than 0.5 m ² / g or more 2.0 m ² / g, more preferably less than 1.0 m ² / g or more 2.0 m ² / g. The tap density of the first silver powder and silver-plated powder (b1) is preferably 2.5 g / cm ³ or more and 6.0 g / cm ³ or less, more preferably 3.0 g / cm ³ or more and 5.0 g / cm ³ or less preferable. Moreover, as for the 50-% average particle diameter of (b1) 1st silver powder, 0.5 micrometer or more and 15 micrometers or less are preferable. The shape of the (b1) first silver powder and the silver-plated powder may be various shapes, and various shapes such as flakes and particles can be used. Among them, flake-like silver powder and silver-plated powder are preferable.

  In addition, in this invention, the tap density of silver powder and silver plating powder can be measured by the method according to the 20.2 tap method of JISK5101-1991. Moreover, 50% average particle diameter is a particle diameter in 50% of the volume accumulation measured by laser diffraction scattering type particle size distribution measuring method.

(B2) a specific surface area of the second silver powder and silver-plated powder preferably 2.0 m ² / g or more 7.0 m ² / g or less, more preferably 2.0 m ² / g or more 3.0 m ² / g. The tap density of the (b2) second silver powder and the silver-plated powder is preferably 1.0 g / cm ³ or more and 3.0 g / cm ³ or less. Moreover, as for the 50% average particle diameter of (b2) 2nd silver powder and silver plating powder, 0.5 micrometer or more and 20 micrometers or less are preferable. In addition, the shapes of (b2) 2nd silver powder and silver plating powder may be various shapes, and various shapes, such as flake shape and a granular form, can be used. Among them, granular silver powder and silver plated powder are preferable.

  In the present invention, the content of the (B) conductive filler is 50% by mass or more and 85% by mass or less, preferably 65% by mass or more and 85% by mass or less, and 70% by mass or more of the total content of the conductive adhesive. 80 mass% or less is more preferable. From the viewpoint of obtaining sufficient conductivity, the content is preferably 50% by mass or more, and from the viewpoint of securing adhesiveness and workability together with excellent conductivity, it is preferably 85% by mass or less. In particular, from the viewpoint of securing adhesiveness and workability, it is preferable that the content of the (b2) second silver powder and the silver-plated powder is not excessively increased.

  When the tap density of the components (b1) and (b2) is within the above range, sufficient conductivity can be exhibited without adding a large amount of silver powder and silver plating powder. From the viewpoint of cost control, in particular, one of the components (b1) and (b2) is a flake-like silver powder and / or a silver-plated powder, and the other is a combination of granular silver powder and / or a silver-plated powder. It is preferable to use it.

[(C) Thixotropic agent]
The conductive adhesive of the present invention can secure thixotropy by using a (C) thixotropy-imparting agent. Examples of the (C) thixotropy-imparting agent include a silica-based compound and / or an amide wax-based compound (hereinafter, the (C) thixotropy-imparting agent may be referred to as "(C) component").

  In the present invention, it is preferable to use, together with the (A) component and the (B) component, at least one silica selected from the group consisting of hydrophobic silica and hydrophobic silica hydrophobized by a specific surface treatment agent. In this case, it is possible to obtain a conductive adhesive which is particularly excellent in the stability of the conductivity. The particle size of silica as the component (C) is not particularly limited, but is preferably a fine silica powder, more preferably a fine silica powder having an average particle size of 7 to 16 nm, and a fine silica powder having an average particle size of 7 to 14 nm. Most preferred.

  Well-known hydrophilic silica can be used widely as hydrophilic silica, and fumed silica in which a silanol group (Si-OH group) exists in the surface among them is preferred. By using hydrophilic silica, it is possible to prevent bleeding while securing flowability without increasing viscosity. The conductive adhesive having flowability is suitable for applications requiring flowability, for example, application to a substrate by screen printing and formation of a pattern with a thin film of about 50 μm.

  As hydrophobic silica, one or more surface treatment agents selected from the group consisting of dimethyldichlorosilane, hexamethyldisilazane, (meth) acrylsilane, octylsilane (eg, trimethoxyoctylsilane etc.), and aminosilane Hydrophobicized hydrophobic silica is used. By using hydrophobic silica hydrophobized with such a specific surface treatment agent, it is possible to prevent bleeding while ensuring dischargeability and shape retention. In the present invention, the conductive adhesive having shape retention property is required to have a film thickness of 100 μm or more in the application where the shape retention property is required, for example, when applying to a substrate by screen printing method to produce a pattern. The present invention is suitable for applications where the conductive adhesive of the present invention is substituted for the case or solder connection portion.

  The hydrophobization treatment method of the silica using a surface treatment agent can select a well-known method, for example, the surface treatment agent mentioned above is sprayed on untreated silica, or the surface treatment agent which vaporized is mixed, and heat treatment is carried out. Methods are included. In addition, it is preferable to process this hydrophobization by the dry condition under nitrogen atmosphere.

  Although the compounding ratio of (C) component does not have a restriction | limiting in particular, It is preferable to use 3 mass parts or more and 20 mass parts or less with respect to 100 mass parts of (A) component, and it is more preferable to use 5 mass parts or more and 10 mass parts or less . The silica which is the component (C) can be used alone or in combination of two or more.

[(D1) Amine Compound, (D2) Compound Producing Amine Compound]
The conductive adhesive of the present invention further includes (D1) an amine compound having at least one alkoxysilyl group in one molecule, and (D2) a compound which reacts with water to form (D1) an amine compound. Amine compounds having at least one alkoxysilyl group in one molecule (hereinafter, D1) are reacted with "(D1) component" and (D2) water to form (D1) amine compounds as "(D2) In some cases. ). Adhesiveness can be further improved by the conductive adhesive containing the (D1) component and / or the (D2) component. The method for producing the compound (D1) is not particularly limited, and known methods can be used.

  Examples of the amine compound having at least one alkoxysilyl group in one molecule (D1) include a compound represented by General Formula (5).

In the general formula (5), 0 ≦ n ≦ 2 (where n is an integer) is satisfied, and n is preferably 0 or 1. Also, R ⁶ and R ⁷ may be the same or different functional groups. For example, each of R ⁶ and R ⁷ is a hydrocarbon group having 1 to 4 carbon atoms, and is an alkyl group such as methyl group, ethyl group, propyl group or butyl group, vinyl group, allyl group, propenyl group And alkenyl groups such as butenyl group are preferable, and alkyl groups are particularly preferable. R ⁸ is a hydrocarbon group having 1 to 10 carbon atoms, and is preferably an alkylene group such as methylene, ethylene, propylene or butylene, an arylene group such as phenylene, an alkylene arylene group, etc. Alkylene is preferred. Z is a hydrogen atom or an aminoalkyl group having 1 or more and 4 or less carbon atoms.

  (D1) Examples of the amine compound having at least one alkoxysilyl group in one molecule include compounds represented by the following formulas (6) to (13), N- (β-aminoethyl) -γ-amino Aminosilanes such as propyltrimethoxysilane and N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane can be exemplified. Among these, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, etc. are electrically conductive. It is particularly preferable from the viewpoint of improving the adhesion of the adhesive.

  (D2) As a compound which reacts with water to form an amine compound represented by the general formula (5), specifically, easiness of obtaining raw materials, good storage stability, reactivity with water, etc. From the viewpoint, ketimine compounds of an amine compound having at least one alkoxysilyl group in one molecule, enamine compounds, and / or aldimine compounds and the like can be mentioned. The ketimine compound, the enamine compound and the aldimine compound can each be produced by the dehydration reaction of an amine compound represented by the general formula (5) having at least one alkoxysilyl group in one molecule and a carbonyl compound.

  As such a carbonyl compound, for example, aldehydes such as acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-amyl aldehyde, isohexyl aldehyde, diethylacetaldehyde, glyoxal, benzaldehyde, phenylacetaldehyde and the like; cyclopentanone, Cyclic ketones such as trimethylcyclopentanone, cyclohexanone, methylcyclohexanone and trimethylcyclohexanone; acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl tert-butyl ketone, diethyl ketone, dipropyl ketone, diisopropyl ketone, Aliphatic ketones such as dibutyl ketone and diisobutyl ketone; acetophenone Aromatic ketones such as benzophenone and propiophenone; β- represented by the following general formula (14) such as acetylacetone, methyl acetoacetate, ethyl acetoacetate, dimethyl malonate, diethyl malonate, methyl ethyl malonate, dibenzoylmethane and the like Dicarbonyl compounds and the like can be mentioned. Among these, methyl isobutyl ketone, dipropyl ketone, phenylacetaldehyde and / or β-dicarbonyl compounds having an active methylene group are more preferable.

In the general formula (14), R ⁹ and R ¹⁰ may be the same or different functional groups. For example, each of R ⁹ and R ¹⁰ is an alkyl group having 1 to 16 carbon atoms (eg, methyl, ethyl, propyl, butyl, heptyl, hexyl, octyl, nonyl, decyl) Group, undecyl group, hexadecyl group, etc., an aryl group having 6 to 12 carbon atoms (eg, phenyl group, tolyl group, hexyl group, naphthyl group, etc.), or 1 to 4 carbon atoms It is an alkoxy group (eg, methoxy group, ethoxy group, proxy group, ptoxy group, etc.).

  The compound which produces | generates the amine compound shown by General formula (5) by reacting with (D2) water mentioned above is not specifically limited. For example, in the present invention, as a compound for producing an amine compound represented by the general formula (5), the monomer purity is 50% to 95%, preferably 70% to 95%, and more preferably 80% to 95%. In the following, it is preferable to use a compound having an amino group blocking ratio of 90% or more, preferably 95% or more. In addition, the compound which concerns can be manufactured by a well-known manufacturing method.

  There are no particular limitations on the blending ratio of the compound (D1) represented by the general formula (5) and the compound (D2) that produces the amine compound represented by the general formula (5). In the present invention, it is preferable to add 1 to 20 parts by mass of these amine compounds to 100 parts by mass of the crosslinkable silicon group-containing organic polymer (A). In addition, the compound which produces | generates the amine compound shown by General formula (5) by reacting with the amine compound shown by (D1) General formula (5), and water (D2) is only 1 type in a conductive adhesive. It can be added or two or more kinds can be added.

[Diluent]
The conductive adhesive of the present invention can also contain a diluent from the viewpoint of adjusting the viscosity. Physical properties such as viscosity can be adjusted by containing a diluent. As the diluent, various diluents can be used. As the diluent, for example, saturated hydrocarbon solvents such as normal paraffin and isoparaffin, α-olefin derivatives such as Linearn dimer (trade name of Idemitsu Kosan Co., Ltd.), aromatic hydrocarbon solvents, alcohol solvents, ester solvents Examples thereof include various solvents such as solvents, citric acid ester solvents such as acetyl triethyl citrate, and ketone solvents.

  In consideration of both the safety and the dilution effect of the conductive adhesive of the present invention, as the diluent, a saturated hydrocarbon solvent is preferable, and normal paraffin and isoparaffin are more preferable. The carbon number of normal paraffins and isoparaffins is preferably 10 to 16.

  The compounding ratio of the diluent is preferably in the range of 0 to 50 parts by mass with respect to 100 parts by mass of the component (A), and more preferably in the range of 0.1 to 40 parts by mass, 0 It is further preferable to blend in the range of 1 to 30 parts by mass. The diluent may be used alone or in combination of two or more.

[Other additives]
In the conductive adhesive according to the present invention, a curing catalyst, a filler, and the like, as needed, from the viewpoint of adjusting physical properties and the like within the range that does not impair the functions such as conductivity and viscosity and thixotropy of the conductive adhesive. Plasticizer, adhesion promoter, stabilizer, coloring agent, physical property modifier, thixotropic agent, dehydrating agent (storage stability improver), tackifier, anti-sagging agent, ultraviolet absorber, antioxidant, flame retardant, A substance such as a radical polymerization initiator or various solvents such as toluene and alcohol may be blended. Also, other polymers compatible may be blended.

(Curing catalyst)
Examples of curing catalysts include titanates such as tetrabutyl titanate and tetrapropyl titanate; organotin compounds such as dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, tin octylate and tin naphthenate: lead octylate Butylamine, octylamine, laurylamine, dibutylamine, monoethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, oleylamine, cyclohexylamine, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine, diphenyl Guanidine, 2,4,6-tris (dimethylaminomethyl) phenol, morpholine, N-methylmorpholine, 1,8-diazabicycline (5. 4.0) Amine compounds such as undecene-7 (DBU) or salts of these with carboxylic acids, etc .; low molecular weight polyamide resins obtained from excess polyamines and polybasic acids; excess polyamines and epoxy Examples thereof include reaction products with compounds; silanol complex catalysts such as silane coupling agents having an amino group such as r-aminopropyltrimethoxysilane and N- (β-aminoethyl) aminopropylmethyldimethoxysilane. These catalysts may be used alone or in combination of two or more. In addition, polymers having fluorosilicone groups substituted with the end of the modified silicone resin by fluorine are also useful as curing catalysts.

(Plasticizer)
As the plasticizer, phthalic acid esters such as dibutyl phthalate, diheptyl phthalate, di (2-ethylhexyl) phthalate, butyl benzyl phthalate, etc .; Basic acid esters; Aliphatic esters such as butyl oleate and methyl acetyl ricinoleate; Phosphoric esters such as tricresyl phosphate and tributyl phosphate; Trimellitic esters; Chlorinated paraffins; Hydrocarbon-based oils such as hydrogenated terphenyl; process oils; epoxy plasticizers such as epoxidized soybean oil and epoxystearic acid benzyl ester.

  In addition, a polymer plasticizer may be used. When a polymer plasticizer is used, the initial physical properties are maintained over a long period of time, as compared with the case where a low molecular plasticizer which is a plasticizer containing no polymer component in the molecule is used. Specific examples of the polymer plasticizer include vinyl polymers obtained by polymerizing vinyl monomers by various methods; esters of polyalkylene glycols such as diethylene glycol dibenzoate, triethylene glycol dibenzoate and pentaerythritol ester; Polyester based plasticizers obtained from dibasic acids such as sebacic acid, adipic acid, azelaic acid, phthalic acid and ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, etc .; Is a polyether polyol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol or more having a hydroxyl group of 1,000 or more, or such polyether polyol, and Polyethers such as derivatives obtained by converting the group or the like; polystyrene and poly -α- polystyrenes methyl styrene and the like; polybutadiene, polybutene, polyisobutylene, butadiene - acrylonitrile, polychloroprene, and the like.

  Among these polymer plasticizers, plasticizers compatible with the component (A) are preferable. From this point, polyethers and vinyl polymers are preferred. The use of polyethers as a plasticizer is preferable because surface curability and deep-part curability are improved, and curing delay after storage does not occur, and polypropylene glycol is more preferable. In addition, vinyl polymers are preferable in terms of compatibility, weather resistance, and heat resistance. Among vinyl polymers, acrylic polymers and / or methacrylic polymers are preferable, and acrylic polymers such as polyacrylic acid alkyl ester are more preferable. The polymer synthesis method is preferably living radical polymerization, since molecular weight distribution is narrow and viscosity can be reduced, and atom transfer radical polymerization is more preferable. Moreover, it is preferable to use the polymer by the so-called SGO process obtained by continuous bulk polymerization of an acrylic acid alkyl ester type monomer at high temperature and pressure.

  The number average molecular weight of the polymer plasticizer is preferably 500 to 15,000, more preferably 800 to 10,000, still more preferably 1,000 to 8,000, and particularly preferably 1,000 to 5,000. And 3,000 to 3,000 are most preferable. If the molecular weight is too low, the plasticizer will flow out over time due to heat and the like, and the initial physical properties can not be maintained for a long time. On the other hand, if the molecular weight is too high, the viscosity is high and the workability is deteriorated. The molecular weight distribution of the polymer plasticizer is not particularly limited, but is preferably narrow and preferably less than 1.80. 1.70 or less is more preferable, 1.60 or less is more preferable, 1.50 or less is more preferable, 1.40 or less is particularly preferable, and 1.30 or less is most preferable. The number average molecular weight can be measured by GPC in the case of vinyl polymers and by end group analysis in the case of polyether polymers. Moreover, molecular weight distribution (Mw (weight average molecular weight) / Mn (number average molecular weight)) can be measured by GPC method (polystyrene conversion).

  Moreover, although a polymer plasticizer can also use the plasticizer which does not have a crosslinkable silicon group, you may have a crosslinkable silicon group. When having a crosslinkable silicon group, it acts as a reactive plasticizer and can prevent migration of the plasticizer from the cured product. When it has a crosslinkable silicon group, it is preferable that the average per molecule is 1 or less, more preferably 0.8 or less. When using a plasticizer having a crosslinkable silicon group, particularly an oxyalkylene polymer having a crosslinkable silicon group, its number average molecular weight needs to be lower than that of the component (A).

  The plasticizer may be used alone or in combination of two or more. In addition, a low molecular plasticizer and a high molecular plasticizer may be used in combination. In addition, these plasticizers can also be mix | blended at the time of manufacture of a conductive adhesive. The amount of the plasticizer used is 5 to 150 parts by mass, preferably 10 to 120 parts by mass, and more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the component (A). If it is less than 5 parts by mass, the effect as a plasticizer can not be exhibited, and if it exceeds 150 parts by mass, the mechanical strength of the cured product is insufficient.

(filler)
Reinforcing fillers such as fume silica, precipitated silica, crystalline silica, fused silica, dolomite, anhydrous silicic acid, hydrous silicic acid, and carbon black as fillers; heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate Diatomaceous earth, calcined clay, clay, talc, titanium oxide, bentonite, organic bentonite, ferric oxide, aluminum fine powder, flint powder, zinc oxide, activated zinc flower, shirasu balloon, glass micro balloon, phenolic resin and vinylidene chloride Fillers such as resin organic micro balloon, resin powder such as PVC powder, PMMA powder and the like; fibrous fillers such as asbestos, glass fibers and filaments and the like.

  When using a filler, the usage-amount is 1-250 mass parts with respect to 100 mass parts of (A) component, and 10-200 mass parts is preferable. These fillers may be used alone or in combination of two or more.

  The filler may be uniformly mixed with a dehydrating agent such as calcium oxide, sealed in a bag made of a gas-tight material, and left in an appropriate time for dehydration drying. By using this low water content filler, especially when it is set as a one-pack type composition, storage stability can be improved.

  When it is desired to obtain a hardened product of high strength by using these fillers, mainly fume silica, precipitated silica, crystalline silica, fused silica, dolomite, silicic anhydride, hydrous silicic acid, carbon black, surface treatment A filler selected from fine calcium carbonate, calcined clay, clay, active zinc flower and the like is preferable, and by using in the range of 1 to 200 parts by mass with respect to 100 parts by mass of the crosslinkable silicon group-containing organic polymer (A). Favorable results are obtained. In addition, when it is desired to obtain a cured product having low strength and high breaking elongation, mainly calcium oxide such as titanium oxide and calcium carbonate with calcium carbonate, magnesium carbonate, talc, ferric oxide, zinc oxide and shirasu balloon Preferred results can be obtained by using a filler selected from the following in a range of 5 to 200 parts by mass with respect to 100 parts by mass of the crosslinkable silicon group-containing organic polymer (A). In general, calcium carbonate has an effect of improving the breaking strength, breaking elongation and adhesion of the cured product as the value of the specific surface area increases. When calcium carbonate is used, it is preferable to use surface-treated fine calcium carbonate in combination with calcium carbonate having a large particle size such as ground calcium carbonate. The particle diameter of the surface-treated fine calcium carbonate is preferably 0.5 μm or less, and the surface treatment is preferably performed with a fatty acid or a fatty acid salt. In addition, the particle diameter of calcium carbonate having a large particle diameter is preferably 1 μm or more, and calcium carbonate not subjected to surface treatment can also be used.

  It is preferable to add an organic balloon and an inorganic balloon from the viewpoint of improving the workability (e.g., peeling) of the composition and making the surface of the cured product matte. These fillers may be subjected to surface treatment, may be used alone, or may be used as a mixture of two or more. The particle diameter of the balloon is preferably 0.1 mm or less in order to improve workability (such as squeezing). From a viewpoint of making hardened | cured material surface matt, 5-300 micrometers is preferable.

(Adhesive agent, stabilizer, coloring agent)
A silane coupling agent and the like can be used as an adhesion promoter, and hindered phenol compounds and triazole compounds can be used as a stabilizer. As a coloring agent, titanium white, carbon black, bengala etc. are mentioned.

[Method of producing conductive adhesive]
The conductive adhesive can be produced by the following procedure. First, a predetermined amount of each of (A) crosslinkable silicon group-containing organic polymer, (B) conductive filler, (C) thixotropic agent, and / or other additives is weighed and prepared (preparation step) . Next, the prepared compound is put into a predetermined container and stirred for a predetermined time (mixing step). Thereby, the conductive adhesive concerning the present invention can be manufactured. In addition, in each process or any process, you may add another additive suitably.

  The conductive adhesive of the present invention can be made into a one-component type, if necessary, or a two-component type. The conductive adhesive of the present invention is particularly suitable for use as a one-component type. In addition, the conductive adhesive of the present invention is suitable for use as a normal temperature moisture-curable conductive adhesive because it hardens at normal temperature by moisture in the air. In the curing of the conductive adhesive, the curing may be promoted by heating (for example, heating at a low temperature of about 80 ° C. to 100 ° C.) as appropriate.

  The conductive adhesive of the present invention has high conductivity by being applied or printed on a substrate and cured, and can be used instead of solder. Therefore, a product having a cured product of the conductive adhesive can be provided. In addition, the conductive adhesive is suitable for use in bonding and mounting of electronic components such as semiconductor element chip components and discrete components, circuit connection, bonding / fixing of crystal oscillators and piezoelectric elements, sealing of packages, etc. There is. The surface of the substrate is a circuit in which one or more kinds of electronic components such as semiconductor elements (including light emitting elements such as light emitting diodes and laser diodes), chip parts, discrete parts are joined using a conductive adhesive. Can be formed into

  In addition, the conductive adhesive of the present invention can be made to have a good balance between viscosity and thixotropy by setting the viscosity and SVI value within a predetermined range, so high-speed dispensers can be used at high speeds at multiple locations. Even if it discharges by this, it can prevent that several places are connected by a conductive adhesive. In addition, since the conductive adhesive of the present invention has a thixotropy within a predetermined range, the conductive adhesive can be prevented from spreading when it is applied to a predetermined base material, so a narrow pitch (for example, 0.5 mm) Conductive adhesive can be applied at the pitch). Furthermore, since the conductive adhesive of the present invention can be cured, for example, at a low temperature of 80 ° C., a substrate (for example, a temperature of about 250 ° C.) which can not withstand the temperature of the solder reflow furnace ( For example, a resin film such as polyethylene terephthalate can also be used. Therefore, the conductive adhesive of the present invention is suitable for use in film devices used for IOT and the like.

[Device manufacturing method]
The following process is mentioned as an example of the manufacturing method of the device using the conductive adhesive of this invention. First, the conductive adhesive of the present invention is applied to a predetermined position of a predetermined base (coating step). A high speed dispenser can be used in the coating process. Although the discharge speed of the dispenser is not particularly limited, for example, it may be a dispenser which can discharge the composition at a speed of 1 shot or less, and the discharge speed is 1 shot 0.85 from the viewpoint of manufacturing cost reduction and the like. It is more preferable that the time is second or less, and further preferably one shot or 0.75 seconds or less.

  Moreover, there is no restriction | limiting in particular in the application | coating space | interval of the electroconductive adhesive by a dispenser, According to the device to manufacture, an application | coating space | interval can be set suitably. For example, the application interval may be 0.8 mm pitch or 0.5 mm pitch. Furthermore, the inner diameter of the nozzle included in the dispenser is not particularly limited as long as the conductive adhesive is applied to an area of about the size or less in plan view of a member to be bonded to a predetermined substrate. 0.1 mm or more and 0.4 mm or less are preferable, and 0.2 mm or more and 0.4 mm or less can also be used.

  The predetermined substrate is not particularly limited, and various substrates and substrates such as a printed substrate and a film substrate can be used. In addition, since the conductive adhesive of the present invention can be cured at a low temperature for a short time, the device manufacturing method of the present invention should be suitably used when using a film substrate such as a resin film having poor heat resistance. You can also.

  Next, the predetermined element is mounted on the conductive adhesive on the substrate (mounting step). Examples of the predetermined element include semiconductor elements, chip parts, and / or discrete parts. Various automatic mounters and the like can be used to mount the elements.

  And the base material which has the element mounted on the base material via a conductive adhesive is heated (heating process). For example, the conductive adhesive is cured by heat treatment at 80 ° C. for a predetermined time (for example, 5 minutes). Thus, a device is manufactured in which a predetermined element is mounted at a predetermined position of a predetermined base material. In addition, since the conductive adhesive of the present invention is cured by the moisture in the air, the element mounted on the substrate via the conductive adhesive does not need to be subjected to the heating process, but according to the passage of time, It is gradually fixed firmly on the substrate.

<Effect of the embodiment>
The conductive adhesive according to the present invention can achieve a good balance of viscosity and thixotropy by setting the viscosity and the SVI value in a predetermined range, so the conductive adhesive can be placed at a plurality of locations with a high-speed dispenser. Even when applied continuously, the conductive adhesives applied can be prevented from being connected to each other, and the spread of the conductive adhesive applied on the substrate can be suppressed. That is, the conductive adhesive according to the present invention is easy to discharge from the nozzle of the high-speed dispenser, and has the characteristics of good sharpness, and an adhesive which exhibits appropriate thixotropy after application and holds the intended shape. It is.

  Furthermore, since the conductive adhesive of the present invention cures at a low temperature such as 80 ° C. in a short time (for example, 5 minutes), electronic elements and the like can be mounted even on a substrate having poor heat resistance. . Moreover, the cured product of the conductive adhesive of the present invention not only exhibits flexibility but is also excellent in heat resistance (for example, the cured product of the conductive adhesive according to the present invention has a temperature of about 120 ° C.) It exerts an excellent effect of exerting appropriate conductivity, strength and the like even under the following conditions. These effects are exhibited better, particularly when a modified silicone resin is used as the component (A).

  Hereinafter, the present invention will be described in more detail by way of examples. Needless to say, these examples are illustrative and should not be construed as limiting.

Synthesis Example 1
In a flask, 40 parts by mass of ethyl acetate as a solvent, 59 parts by mass of methyl methacrylate, 25 parts by mass of 2-ethylhexyl methacrylate, 22 parts by mass of γ-methacryloxypropyltrimethoxysilane, and 0.1 parts by mass of ruthenocene dichloride as a metal catalyst Charge and heat to 80 ° C. while introducing nitrogen gas. Then, 8 parts by mass of 3-mercaptopropyltrimethoxysilane was added into the flask and reacted at 80 ° C. for 6 hours. After cooling to room temperature, 20 parts by mass of a benzoquinone solution (95% THF solution) was added to terminate the polymerization. A solvent and an unreacted material are distilled off, and an acrylic ester polymer having a trimethoxysilyl group having a polystyrene equivalent weight average molecular weight of about 6,000 and a glass transition point (Tg) of 61.2 ° C. Obtained.

(Examples 1-2, comparative examples 1-2)
Each compounded material was added at a blending ratio shown in Table 1 to prepare a conductive adhesive in accordance with the description of the above-mentioned "Method of Manufacturing Conductive Adhesive". Specifically, each of the component A, the component B, the component C, and the other additives was weighed and prepared so as to obtain the mixture ratio shown in Table 1. Next, they were mixed and stirred. Thereby, the conductive adhesive concerning Example 1-2 and Comparative Examples 1-2 was obtained.

In Table 1, the unit of the compounding amount of each compounding substance is "mass part". Moreover, the details of the compounding substance are as follows. In addition, the polymer synthesize | combined by the said synthesis example 1 was used for the acrylic acid ester type polymer of A component.
(A component)
SPUR + 1050MM (manufactured by Momentive)
Cyril MA 440 (manufactured by Kaneka Corporation)
(B component)
Sil coat AgC-B (Fukuda metal foil powder industrial company make)
Sil coat AgC-G (Fukuda metal foil powder industrial company make)
(C ingredient)
Aerosil R 972 (made by Nippon Aerosil)
(Antioxidant)
Irganox 245 (manufactured by BASF)
(Diluent)
Normal paraffin N-11 (JX Nippon Steel Corporation)
Isopropanol (manufactured by Wako Pure Chemical Industries, Ltd.)
Dimethoxyethane (manufactured by Nippon Emulsifier)
(Dehydrating agent)
Silicone KBM-1003 (Shin-Etsu Chemical Co., Ltd.)
(Adhesive agent)
Silicone KBM-903 (Shin-Etsu Chemical Co., Ltd.)
(Curing catalyst)
Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.)
Neostan S-1 (manufactured by Nitto Kasei Co., Ltd.)

(Viscosity measurement)
The viscosity of the conductive adhesive according to Example 1 was measured using a BH rotational viscometer (No. 7) at a rotational speed of 20 r / min under a temperature condition of 23 ° C. in accordance with JIS K 6833-1. . It measured similarly about Example 2 and Comparative Examples 1-2.

(SVI value measurement)
The conductive adhesive according to Example 1 was measured using a B-type viscometer in accordance with JIS K 6833-1, at a temperature of 23 ° C., at a low rotation speed (rotation speed 2 r / min). The viscosity A and the viscosity B at a high rotation speed (rotational speed 20 r / min) were measured, and their ratio (A / B) was calculated as the SVI value. The SVI values were similarly calculated for Example 2 and Comparative Examples 1 and 2.

(Measurement of volume resistivity)
The conductive adhesive according to Example 1 was coated on a glass plate at a size of 70 mm × 100 mm using a masking tape having a thickness of 100 μm as a spacer, and dried at 80 ° C. for 20 minutes. Then, it cooled to room temperature and obtained the test piece of the dried conductive adhesive. And the volume resistivity (volume resistivity immediately after drying) of this test piece was measured using Lorester MCP-T360 (made by Mitsubishi Analytech Co., Ltd.). The volume resistivity was similarly measured for Example 2 and Comparative Examples 1 and 2.

(Dispense accuracy test)
Using an automatic dispenser YDG manufactured by Yamaha Motor, the nozzle diameter is 1.0 mm, the discharge pressure is 0.1 MPa, the flow speed is adjusted to 0.5 sec / point under flow 10 conditions, and the device is adjusted by inkjet. The conductive adhesive according to Example 1 was discharged onto each electrode of a PET film (hereinafter referred to as a "test film") printed with a circuit of (a light emitting diode). After discharge, the case where there was no bridge between the electrodes by visual observation was evaluated as "o", and the case where there was a bridge was evaluated as "x". It evaluated similarly about Example 2 and Comparative Examples 1-2. In addition, about the electroconductive adhesive which concerns on the comparative example 2, since one point was not able to apply | coat also on said dispensing conditions, evaluation was made into "x".

  FIG. 1 shows the test film used for the dispensing accuracy test. Specifically, FIG. 1 (a) shows a part of the back surface of a test film when the conductive adhesive according to Example 1 is used, and FIG. 1 (b) shows the conductive adhesive according to Comparative Example 1. Shows a part of the surface of the test film when using.

  As shown in FIG. 1A, when the conductive adhesive 20 according to Example 1 is used, it is confirmed that the conductive adhesive 20 does not protrude from the electrode 10 and that no bridge is generated between the electrodes. The That is, in the state observed from the back of the test film of FIG. 1 (a), the back of the LED chip 60 (the part with the cross mark in FIG. 1 (a)) is observed between the electrodes 10. From the above, it was determined that the conductive adhesive 20 was appropriately applied to the region on the surface of the test film on the electrodes 10, and that there was no occurrence of bridging between the electrodes 10 or occurrence of protrusion from the electrodes 10. In FIG. 1A, the substantially circular or elliptical area 50 observed around the LED chip 60 is transparent to the sealing resin for sealing the LED chip 60 mounted on the surface side of the PET film. It is what you see. On the other hand, as shown in FIG. 1B, when the conductive adhesive 30 according to Comparative Example 1 is used, it is confirmed that the conductive adhesive 30 protrudes from the electrode 10 and a bridge 40 is generated between the electrodes. The

  From the above, all of the conductive adhesives according to the examples have suitable viscosity and SVI values and have good volume resistivity, and even after high-speed application with a dispenser, after application It has been shown that the prescribed shape can be maintained and applied properly. In addition, in Example 1 of Fig.1 (a), lighting of LED was also confirmed.

  Although the embodiments and examples of the present invention have been described above, the embodiments and examples described above do not limit the invention according to the claims. In addition, not all combinations of features described in the embodiments and examples are essential to the means for solving the problems of the invention, and various combinations without departing from the technical concept of the invention. It should be noted that variations are possible.

10 electrode 20 conductive adhesive 30 conductive adhesive 40 bridge 50 area 60 LED chip

Claims (8)

A conductive adhesive that can be applied at high speed using a dispenser and can be cured at low temperatures,
Structural Viscosity Index (SVI) value is 2.5 or more and 6 or less,
The conductive adhesive whose viscosity in 23 degreeC is 1 Pa.s or more and 20 Pa.s or less. The conductive adhesive is
(A) a crosslinkable silicon group-containing organic polymer,
(B) conductive filler,
The conductive adhesive according to claim 1, containing (C) a thixotropic agent. The main chain skeleton of the crosslinkable silicon group-containing organic polymer (A) is selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers, and (meth) acrylic acid ester polymers 1 More than species,
The (B) conductive filler includes (b1) a first silver powder and a silver-plated powder, and (b2) a second silver powder and a silver-plated powder.
The conductive adhesive according to claim 2, wherein the (C) thixotropic agent is a silica-based compound or an amide wax-based compound. The specific surface area of the first silver powder and the silver-plated powder (b1) is 0.5 m ² / g or more and less than 2.0 m ² / g, and the tap density is 2.5 to 6.0 g / cm ³ ,
The specific surface area of the (b2) second silver powder and silver-plated powder is 2.0 m ² / g or more and 7.0 m ² / g or less, and the tap density is 1.0 to 3.0 g / cm ³ ,
The mixing ratio [(b1) / (b2)] of (b1) to (b2) is 1/10 or more and 10/1 or less in mass ratio,
The silica-based compound which is the (C) thixotropy-imparting agent is selected from the group consisting of hydrophobic silica hydrophobized by a surface treatment agent and hydrophilic silica which is fumed silica having a silanol group on the surface. The conductive adhesive according to claim 3, wherein the conductive adhesive is one or more kinds of silica. The (B) conductive filler is 65% by mass or more and 85% by mass or less of the total content,
The conductive adhesive according to claim 4, wherein the surface treatment agent is one or more selected from the group consisting of dimethyldichlorosilane, hexamethyldisilazane, (meth) acrylsilane, octylsilane, and aminosilane.   The conductive adhesive according to any one of claims 1 to 5, further comprising a diluent.   An article having a cured product of the conductive adhesive according to any one of claims 1 to 6. An application step of applying the conductive adhesive according to any one of claims 1 to 6 to a predetermined place of a substrate,
Mounting a device on the conductive adhesive on the substrate;
Heating the substrate having the element mounted on the substrate via the conductive adhesive.

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