WO2018230109A1

WO2018230109A1 - Conductive resin composition and production method for shielded package using same

Info

Publication number: WO2018230109A1
Application number: PCT/JP2018/014287
Authority: WO
Inventors: 梅田　裕明; 和大松田; 元中園
Original assignee: タツタ電線株式会社
Priority date: 2017-06-15
Filing date: 2018-04-03
Publication date: 2018-12-20
Also published as: TW201904764A; CN110382620A; JP2019001912A; KR20200019593A

Abstract

Provided are: a conductive resin composition which has good shielding properties, good adhesion to a package, and which can, by spray coating, form a shield layer that is less likely to discolor even under severe heating conditions; and a production method for a shielded package using the conductive resin composition. The conductive resin composition contains at least (A) a compound which is represented by general formula (I), has a molecular weight of 500-2000, and has two or more maleimide groups in one molecule, (B) a thermosetting compound, (C) a compound having an imidazole group, and (D) a conductive filler.

Description

Conductive resin composition and method for producing shield package using the same

The present invention relates to a conductive resin composition and a method for producing a shield package using the same.

In recent years, electronic devices such as mobile phones and tablet terminals are equipped with a large number of electronic components for wireless communication for transmitting large amounts of data. Such electronic components for wireless communication are not only prone to generate noise but also have a high sensitivity to noise, and have a problem that they are liable to malfunction when exposed to external noise.

On the other hand, it is required to increase the mounting density of electronic components in order to achieve both a reduction in size and weight of electronic devices and an increase in functionality. However, when the mounting density is increased, not only the number of electronic components that are sources of noise increases, but the number of electronic components that are affected by noise also increases.

Conventionally, as a means for solving this problem, a so-called shielded package that prevents generation of noise from the electronic component and prevents intrusion of noise by covering the electronic component that is a source of noise with a shield layer together with the package. It has been known. For example, in Patent Document 1, an electromagnetic shielding member having a high shielding effect is easily obtained by spraying (coating) a conductive resin composition containing conductive particles on the surface of a package, coating, and heat-curing. It is stated that it can.

However, when the conventional shield package is put into the solder reflow process, the color of the shield layer changes and it is difficult to obtain a preferable appearance. On the other hand, if the shield layer is formed using high-purity silver particles, discoloration can be suppressed, but it is expensive and therefore lacks versatility.

On the other hand, when copper powder or silver-coated copper powder is used, the price of the conductive resin composition can be suppressed, but the color of the shield layer obtained by heat curing the conductive resin composition changes. Have

It can be presumed that the cause of discoloration of the shield layer made of the conductive resin composition using copper powder or silver-coated copper powder is due to the interaction between the resin composition and copper powder or silver-coated copper powder. Therefore, it is thought that discoloration can be suppressed by reducing the amount of copper powder or silver-coated copper powder in the resin composition. However, if the blending amount of the copper powder or silver-coated copper powder in the resin composition is reduced, the resistance value of the resin composition increases, which causes a problem that the shielding effect of the package is reduced.

JP 2003-258137 A

The present invention has been made in view of the above, and is a conductive resin composition in which a shield layer having good shielding properties can be formed by spray coating, and the obtained shield layer has good adhesion to a package. Therefore, it is an object to provide a conductive resin composition that is difficult to discolor even under severe heating conditions at a low cost. Another object of the present invention is to provide a method for manufacturing a shield package in which the shield layer as described above can be easily formed.

The conductive resin composition according to the present invention includes (A) a compound represented by the following general formula (I), a molecular weight of 500 to 2000, and having two or more maleimide groups in one molecule, (B) thermosetting A conductive compound, (C) a compound having an imidazole group, and (D) a conductive filler.

However, in the formula (I), X represents an aliphatic, alicyclic or aromatic hydrocarbon group which is a hydrocarbon group having 10 to 30 carbon atoms in the main chain, and these groups are , A hetero atom, a substituent, or a siloxane skeleton.

The thermosetting compound (B) may be at least one selected from the group consisting of an epoxy resin that is solid at room temperature, an epoxy resin that is liquid at room temperature, and a (meth) acrylate compound. .

The content of the compound (C) having an imidazole group is 0.5 to 50 parts by mass with respect to 100 parts by mass of the total amount of the compound (A) having the maleimide group and the thermosetting compound (B). It can be assumed that

The content of the conductive filler (D) is 200 to 1800 parts by mass with respect to 100 parts by mass of the total amount of the maleimide group-containing compound (A) and the thermosetting compound (B). can do.

The conductive filler (D) may be copper powder, silver-coated copper powder, or silver-coated copper alloy powder.

The conductive resin composition according to the present invention can be used for shielding electronic component packages.

A method of manufacturing a shield package according to the present invention is a method of manufacturing a shield package in which an electronic component is mounted on a substrate, and the package in which the electronic component is sealed with a sealing material is covered with a shield layer. A step of sealing the electronic component by mounting a plurality of electronic components on the substrate, filling the substrate with a sealing material, and curing, and cutting the sealing material between the plurality of electronic components Forming a package of each electronic component on the substrate by these groove portions, applying the conductive resin composition to the surface of the individualized package by spraying, and the surface of the package Heating the substrate coated with the conductive resin composition to form a shield layer by curing the conductive resin composition, and extending the substrate along the groove It can be assumed to have at least a step of obtaining a shielding package singulation by cutting.

According to the conductive resin composition of the present invention, a coating film having a uniform thickness can be formed by a spray method, and the obtained coating film can suppress discoloration even under severe heating conditions. Therefore, by applying the conductive resin composition of the present invention to the package surface by spraying, it becomes possible to easily form a shield layer having excellent shielding effect and appearance and excellent adhesion to the package.

Further, according to the method for manufacturing a shield package of the present invention, it is possible to efficiently manufacture a shield package having excellent shielding properties, discoloration resistance and adhesion to the package as described above without using a large-scale apparatus. it can.

It is a schematic cross section which shows one Embodiment of the manufacturing method of a shield package. It is a top view which shows the example of the shield package before individualization. It is a top view which shows the board | substrate with which the sample of the hardened | cured material used for evaluation of the electroconductivity of a conductive coating film was formed.

A: Individualized package on the board
B …… Separated shield package,
B ₁ , B ₂ , B ₉ ...... Shield package before being separated,
1 ... Board, 2 ... Electronic components, 3 ... Ground circuit pattern (copper foil),
4 ... Sealing material, 5 ... Shield layer (conductive coating), 11-19 ... Groove,
20 ... Substrate, 21 ... Electrode pad, 22 ... Cured product of conductive resin composition

As described above, the conductive resin composition according to the present invention is (A) a compound represented by the following general formula (I), having a molecular weight of 500 to 2000, and having two or more maleimide groups in one molecule, B) contains at least a thermosetting compound, (C) a compound having an imidazole group, and (D) a conductive filler. The use of the conductive resin composition is not particularly limited, but a shield layer is formed by spraying spray or the like on the surface of the package before being singulated or on the surface of the singulated package. Therefore, it is preferably used for obtaining a shield package.

Here, in the formula (I), X represents an aliphatic, alicyclic, or aromatic hydrocarbon group, which is a hydrocarbon group having 10 to 30 carbon atoms in the main chain. May have a heteroatom, a substituent, or a siloxane skeleton.

X is preferably an aliphatic or alicyclic hydrocarbon group, or an aliphatic hydrocarbon group modified with an alicyclic hydrocarbon group, and an aliphatic hydrocarbon group modified with an alicyclic hydrocarbon group Is particularly preferred. The main chain of X preferably has 10 to 30 carbon atoms, more preferably 15 to 25 carbon atoms. When the number of carbons in the main chain of X is in the range of 10 to 30, the shield layer obtained by heat curing is blackened by using together with the compound (C) having an imidazole group. Even if it is added, the discoloration of the shield layer becomes inconspicuous. Further, the aliphatic hydrocarbon group including the side chain preferably has 10 to 55 carbon atoms, and more preferably 10 to 40 carbon atoms.

The molecular weight of the compound (A) is preferably 500 or more, and more preferably 550 or more. When the molecular weight is 500 or more, the shield layer obtained by heat-curing is blackened, so that the discoloration of the shield layer is not noticeable even if it is put into the solder reflow process. In addition, the conductive filler is less likely to settle during storage of the conductive resin composition. Furthermore, after applying the conductive resin composition to the package, it can be prevented from dripping on the wall surface of the package, and a uniform coating film can be easily formed.

The molecular weight of the compound (A) is preferably 2000 or less, more preferably 1000 or less, and still more preferably 900 or less. When the molecular weight is 2000 or less, the shield layer obtained by heat curing is blackened. Therefore, even if it is put into the solder reflow process, discoloration of the shield layer is not noticeable. Moreover, it becomes easy to form a uniform coating film after the conductive resin composition is applied to the package.

The method for producing the compound (A) is not particularly limited, and for example, it can be produced by a known method in which an acid anhydride and a diamine are subjected to a condensation reaction and then dehydrated and cyclized (imidized).

Examples of acid anhydrides that can be used in the production include polybutadiene-graft-maleic anhydride; polyethylene-graft-maleic anhydride; polyethylene-maleic anhydride alternating copolymer; polymaleic anhydride-1-octadecene alternating copolymer Polypropylene-graft-maleic anhydride; poly (styrene-maleic anhydride) copolymer; pyromellitic anhydride; maleic anhydride, succinic anhydride; 1,2,3,4-cyclobutanetetracarboxylic dianhydride 1,4,5,8-naphthalenetetracarboxylic dianhydride; 3,4,9,10-perylenetetracarboxylic dianhydride; bicyclo (2.2.2) oct-7-ene-2,3 , 5,6-tetracarboxylic dianhydride; diethylenetriaminepentaacetic acid dianhydride; ethylenediaminetetraacetic acid dianhydride; ', 4,4'-benzophenonetetracarboxylic dianhydride; 3,3', 4,4'-biphenyltetracarboxylic dianhydride; 4,4'-oxydiphthalic anhydride; 3,3 ', 4 , 4′-diphenylsulfonetetracarboxylic dianhydride; 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride; 4,4′-bisphenol A diphthalic anhydride; 2,5-dioxytetrahydro) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride; ethylene glycol bis (trimellitic anhydride); hydroquinone diphthalic anhydride; allyl nadic acid anhydride ( allyl nadic anhydride); 2-octen-1-ylsuccinic anhydride; phthalic anhydride; 1,2,3,6-tetrahydrophthal 3,4,5,6-tetrahydrophthalic anhydride; 1,8-naphthalic anhydride; glutaric anhydride; dodecenyl succinic anhydride; hexadecenyl succinic anhydride; hexahydrophthalic anhydride Methylhexahydrophthalic anhydride; tetradecenyl succinic anhydride and the like.

Examples of diamines include 1,10-diaminodecane; 1,12-diaminododecane; dimer diamine; 1,2-diamino-2-methylpropane; 1,2-diaminocyclohexane; 1,2-diaminopropane; 1,4-diaminobutane; 1,5-diaminopentane; 1,7-diaminoheptane; 1,8-diaminomentane; 1,8-diaminooctane; 1,9-diaminononane; '-Diamino-N-methyldipropylamine;diaminomaleonitrile;1,3-diaminopentane;9,10-diaminophenanthrene;4,4'-diaminooctafluorobiphenyl; 3,5-diaminobenzoic acid; -Diamino-2-methoxyfluorene; 4,4'-diaminobenzophenone; 3,4-diaminoben 3,4-diaminotoluene; 2,6-diaminoanthraquinone; 2,6-diaminotoluene; 2,3-diaminotoluene; 1,8-diaminonaphthalene; 2,4-diaminotoluene; 2,5-diaminotoluene 1,4-diaminoanthraquinone; 1,5-diaminoanthraquinone; 1,5-diaminonaphthalene; 1,2-diaminoanthraquinone; 2,4-cumenediamine; 1,3-bisaminomethylbenzene; 2-methyl-1,4-diaminobenzene; 1,4-diamino-2,5-dichlorobenzene; 1,4-diamino-2,5-dimethylbenzene; 4,4′-diamino-2, 2′-bistrifluoromethylbiphenyl; bis (amino-3-chlorophenyl) ethane; bis (4-amino -3,5-dimethylphenyl) methane; bis (4-amino-3,5-diethylphenyl) methane; bis (4-amino-3-ethyldiaminofluorene; diaminobenzoic acid; 2,3-diaminonaphthalene; 2 , 3-diaminophenol; -5-methylphenyl) methane; bis (4-amino-3-methylphenyl) methane; bis (4-amino-3-ethylphenyl) methane; 4,4'-diaminophenylsulfone; 2,2-bis (4- (4aminophenoxy) phenyl) sulfone; 2,2-bis (4- (3-aminophenoxy) phenyl) sulfone; 4,4'-oxydi 4,4′-diaminodiphenyl sulfide; 3,4′-oxydianiline; 2,2-bis (4- (4-aminophenoxy) pheny ) Propane; 1,3-bis (4-aminophenoxy) benzene; 4,4′-bis (4-aminophenoxy) biphenyl; 4,4′-diamino-3,3′-dihydroxybiphenyl; 4,4′- Diamino-3,3′-dimethylbiphenyl; 4,4′-diamino-3,3′-dimethoxybiphenyl; Bisanline M; Bisanline P; 9,9-bis (4-aminophenyl) fluorene; o-tolidine sulfone; (Anthranilic acid); 1,3-bis (4-aminophenoxy) -2,2-dimethylpropane; 1,3-bis (4-aminophenoxy) propane; 1,4-bis (4-aminophenoxy) butane; 1,5-bis (4-aminophenoxy) butane; 2,3,5,6-tetramethyl-1,4-phenylenediamine; 3,3 ', 5,5'-tetramethylbenzidine;4,4'-diaminobenzanilide; 2,2-bis (4-aminophenyl) hexafluoropropane; polyoxyalkylene diamines (eg Jeffamine D-230 from Huntsman) , D400, D-2000 and D-4000); 1,3-cyclohexanebis (methylamine); m-xylylenediamine; p-xylylenediamine; bis (4-amino-3-methylcyclohexyl) methane; 2-bis (2-aminoethoxy) ethane; 3 (4), 8 (9) -bis (aminomethyl) tricyclo (5.2.1.0 ^2,6 ) decane, 1,2-bis (aminooctyl) -3-octyl-4-hexyl-cyclohexane and the like. Among these, diamines having 10 to 30 carbon atoms in the main chain of the alkyl chain are preferable from the viewpoint of obtaining a resin impregnated product and a cured product exhibiting excellent dielectric properties and strength.

As the compound (A), a commercially available compound can be used. As a preferable example, DESIGNER MOLECURES Inc. BMI-689 (synthesized from dimer diamine and maleic anhydride) and the like can be suitably used. BMI-689 is represented by the following structural formula.

Although it does not specifically limit as said thermosetting compound (B), The compound which has an epoxy group, the compound which has a (meth) acryloyl group, a phenol resin, a melamine resin, a silicon resin, an alkyd resin, a xylene resin etc. are used. be able to. These may be used alone or in combination of two or more. Among these, it is preferable to contain a compound having an epoxy group or a compound having a (meth) acryloyl group.

By using the thermosetting compound (B) as described above, it does not soften even when exposed to the solder reflow process, and it is easy to maintain the function as a package.

The content of the compound (B) is preferably 30 to 90 parts by mass, and more preferably 50 to 85 parts by mass, in 100 parts by mass in total with the compound (A). Hereinafter, in the present specification, a mixture of the compound (A) and the compound (B) is used as a binder component.

When a compound having an epoxy group is used as the compound (B), an epoxy resin that is solid at room temperature (hereinafter sometimes referred to as “solid epoxy resin”) and an epoxy resin that is liquid at room temperature (hereinafter referred to as “liquid”). Any of the “epoxy resins” may be used.

As used herein, “solid at normal temperature” for an epoxy resin means a state that does not have fluidity in a solvent-free state at 25 ° C., and “liquid at normal temperature” has fluidity under the same conditions. It means to be in a state.

The solid epoxy resin can be used by dissolving in a solvent. The solvent to be used is not particularly limited, and can be appropriately selected from those described below.

Specific examples of the solid epoxy resin include, but are not limited to, bisphenol type epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, spiro ring type epoxy resin, naphthalene type epoxy resin. , Biphenyl type epoxy resin, terpene type epoxy resin, glycidyl ether type epoxy resin such as tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) ethane, glycidylamine type epoxy resin such as tetraglycidyldiaminodiphenylmethane, tetrabromobisphenol A Type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, α-naphthol novolak type epoxy resin, brominated pheno Novolac type novolak epoxy resin having an epoxy resin, rubber-modified epoxy resins. These can be used alone or in combination of two or more.

Specific examples of the epoxy resin that is liquid at normal temperature include, but are not particularly limited to, liquid glycidylamine epoxy resins and liquid glycidyl ether epoxy resins, and are preferably liquid glycidylamine epoxy resins.

The compound having the (meth) acryloyl group is not particularly limited as long as it has an acryloyl group or a methacryloyl group. For example, isoamyl acrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, Examples include 2-hydroxy-3-acryloyloxypropyl methacrylate, phenylglycidyl ether acrylate hexamethylene diisocyanate urethane prepolymer, bisphenol A diglycidyl ether acrylic acid adduct, ethylene glycol dimethacrylate, and diethylene glycol dimethacrylate. These can be used alone or in combination of two or more.

When the compound having an epoxy group and the compound having a (meth) acryloyl group are used in combination as the compound (B), the content ratio of the compound having a (meth) acryloyl group is the compound having an epoxy group and (meth) The total amount with the compound having an acrylate group is preferably 5 to 95% by mass, more preferably 20 to 80% by mass. When the compound having a (meth) acrylate group is 5% by mass or more, the storage stability of the conductive resin composition is excellent, the conductive resin composition can be quickly cured, and further, the coating dripping at the time of curing can be prevented. Can be prevented. Moreover, when the compound which has a (meth) acrylate group is 95 mass% or less, the adhesiveness of a package and a shield layer tends to become favorable.

In the present invention, a compound (C) having an imidazole group is used to cure the binder component. By using the compound (C) having an imidazole group as a curing agent, when the coating layer made of the conductive resin composition of the present invention is heated and cured to form a shielding layer, the resulting shielding layer is blackened. For this reason, even if the solder reflow process is performed, discoloration of the shield layer is less noticeable.

The compound (C) having an imidazole group used in the present invention is not particularly limited, and examples thereof include imidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenyl. Examples include imidazole, 2-ethyl-4-methyl-imidazole, and 1-cyanoethyl-2-undecylimidazole. These may be used alone or in combination of two or more.

The content of the compound (C) having an imidazole group is not particularly limited, but usually it is preferably 0.5 to 50 parts by mass and preferably 5 to 50 parts by mass with respect to 100 parts by mass of the binder component. More preferred. When the content of the compound (C) having an imidazole group is 0.5 parts by mass or more, the adhesion between the shield layer and the package surface and the conductivity of the shield layer become good, and the shield layer has an excellent shielding effect. Is easily obtained, and when it is 50 parts by mass or less, the storage stability of the conductive resin composition is easily maintained. In addition to the compound (C) having an imidazole group, a radical curing agent can be used as a curing agent, and the content thereof is 0.3 to 8 parts by mass with respect to 100 parts by mass of the binder component. It is preferable that When the content of the radical curing agent is 0.3 parts by mass or more, the adhesion between the conductive coating film and the surface of the coating object and the conductivity of the conductive coating film become good, and the conductivity is excellent in the shielding effect. If the amount is 8 parts by mass or less, the storage stability of the conductive resin composition is improved.

The conductive filler (D) in the conductive resin composition of the present invention is not particularly limited, but is preferably copper powder, silver powder, silver nanopowder, silver-coated copper powder, or silver-coated copper alloy powder. More preferably, silver-coated copper powder or silver-coated copper alloy powder. The silver-coated copper alloy powder may have a copper alloy powder and a silver-containing layer that covers the copper alloy powder. Further, the copper alloy powder may have a nickel content of 0.5 to 20% by mass and a zinc content of 1 to 20% by mass. Nickel and zinc are included within the above-described range, and the balance is made of copper, and the balance of copper may contain unavoidable impurities. Thus, the shield package excellent in shielding property can be obtained by using the copper alloy powder which has a silver coating layer.

The silver coating amount is preferably 3 to 30% by mass and more preferably 5 to 20% by mass in the ratio of silver-coated copper powder or silver-coated copper alloy powder. When the silver coating amount is 3% by mass or more, it is easy to suppress discoloration of the shield package even under severe heating conditions, and good conductivity can be obtained. When the silver coating layer is 30% by mass or less, a package having excellent shielding properties can be obtained at low cost.

Examples of the shape of the conductive filler (D) include flakes (scales), dendrites, spheres, fibers, irregular shapes (polyhedrons), etc., but the resistance value is lower and the shielding property is more. From the viewpoint of obtaining an improved shield layer, a flake shape is preferred.

When the conductive filler (D) is flaky, the tap density of the conductive filler (D) is preferably 4.0 to 6.5 g / cm ³ . When the tap density is within the above range, the conductivity of the shield layer becomes better.

Further, when the conductive filler (D) is flaky, the conductive filler (D) preferably has an aspect ratio of 2 to 10. When the aspect ratio is within the above range, the conductivity of the shield layer becomes better.

The average particle diameter of the conductive filler (D) is preferably 1 to 30 μm. When the average particle diameter of the conductive filler (D) is 1 μm or more, the dispersibility of the conductive filler (D) is good and aggregation can be prevented, and it is difficult to oxidize. Good connectivity.

The content of the conductive filler (D) is not particularly limited, but is preferably 200 to 1800 parts by mass with respect to 100 parts by mass of the binder component. When the content is 200 parts by mass or more, the conductivity of the shield layer is good, and when it is 1800 parts by mass or less, the adhesion between the shield layer and the package and the physical properties of the conductive resin composition after curing are good. Thus, the shield layer is less likely to be chipped when cut with a dicing saw described later. Further, even if the conductive coating is heat-cured and then left undisturbed due to the blackening of the resin, the discoloration becomes inconspicuous.

In addition, known additives such as antifoaming agents, thickeners, pressure-sensitive adhesives, fillers, flame retardants, and colorants are added to the conductive resin composition of the present invention within a range that does not impair the purpose of the invention. be able to.

The conductive resin composition of the present invention preferably has a lower viscosity than the so-called conductive paste so that the conductive resin composition can be uniformly applied to the package surface by spraying.

The viscosity of the conductive resin composition of the present invention is preferably adjusted as appropriate according to the application and the equipment used for coating, and is not particularly limited, but general guidelines are as described below. The method for measuring the viscosity is not limited, but if the conductive resin composition has a low viscosity, it can be measured with a cone-plate rotational viscometer (so-called cone-plate viscometer). For example, it can be measured with a single cylindrical rotational viscometer (so-called B-type or BH-type viscometer).

When measuring with a cone-plate rotational viscometer, the viscosity measured at 0.5 rpm using a cone field CP40 (Cone angle: 0.8 °, cone radius: 24 mm) manufactured by Brookfield is 100 mPa. · It is preferably at least s, more preferably at least 150 mPa · s. When the viscosity is 100 mPa · s or more, it is easy to form a conductive coating film without unevenness by preventing dripping when the coated surface is not horizontal. In addition, in the case of near 100 mPa · s or lower viscosity, in order to obtain a uniform coating film having a desired thickness, a thin film is formed by reducing the coating amount once, and a thin film is formed thereon. A so-called overcoating method that repeats the operation is effective. If the viscosity is measurable with a conical plate type rotational viscometer, there is no problem even if it is high.

Rotator No. when measuring with a single cylindrical rotational viscometer. The viscosity measured at 10 rpm using 5 is preferably 30 dPa · s or less, and more preferably 25 dPa · s or less. When it is 30 dPa · s or less, the spray nozzle is prevented from being clogged, and a conductive coating film is easily formed without unevenness. If the viscosity is measurable with a single cylindrical rotational viscometer, there is no problem even if it is low.

Since the viscosity of the conductive resin composition varies depending on the viscosity of the binder component, the content of the conductive filler, and the like, a solvent can be used so as to be within the above range. The solvent that can be used in the present invention is not particularly limited. For example, propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butyl acetate, acetone, methyl ethyl ketone, acetophenone, methyl cellosolve, methyl cellosolve acetate, methyl carbitol , Diethylene glycol dimethyl ether, tetrahydrofuran, butyl acetate, methyl acetate and the like. These may be used alone or in combination of two or more.

It is preferable that the content of the solvent is appropriately adjusted according to the use of the conductive resin composition and the equipment used for coating. Accordingly, although it varies depending on the viscosity of the binder component, the content of the conductive filler, and the like, the standard is about 10 to 60% by mass with respect to the total amount of the components (excluding the solvent) of the conductive resin composition.

The shield layer obtained by the conductive resin composition of the present invention is excellent in adhesion with a ground circuit formed of copper foil or the like. Specifically, since the adhesion between the copper foil of the ground circuit exposed from a part of the shield package and the shield layer is good, after the conductive resin composition is applied to the shield package surface and the shield layer is formed When the package is cut into individual pieces, it is possible to prevent the shield layer from being peeled off from the ground circuit due to an impact at the time of cutting.

When used as a shield layer, the coating film formed from the conductive resin composition of the present invention preferably has a specific resistance of 2 × 10 ⁻⁴ Ω · cm or less from the viewpoint of obtaining excellent shielding properties. .

Next, an embodiment of a method for obtaining a shield package using the conductive resin composition of the present invention will be described with reference to the drawings.

First, as shown in FIG. 1A, a plurality of electronic components (IC or the like) 2 are mounted on a substrate 1 and a ground circuit pattern (copper foil) 3 is provided between the plurality of electronic components 2. prepare.

Next, as shown in FIG. 5B, the electronic component 2 is sealed by filling the electronic component 2 and the ground circuit pattern 3 with a sealing material 4 and curing it.

Next, as indicated by arrows in FIG. 2C, the sealing material 4 is cut between the plurality of electronic components 2 to form grooves, and the packages of the electronic components on the substrate 1 are individualized by these grooves. Let Reference symbol A indicates an individual package. At least a part of the ground circuit is exposed from the wall surface constituting the groove, and the bottom of the groove does not completely penetrate the substrate.

On the other hand, a predetermined amount of the binder component, the conductive filler and the curing agent described above and a solvent used as necessary are mixed to prepare a conductive resin composition.

Next, the conductive resin composition is sprayed in the form of a mist with a known spray gun or the like and applied evenly on the package surface. The spray pressure and spray flow rate at this time, and the distance between the spray gun spray port and the package surface are appropriately set as necessary.

Next, the package coated with the conductive resin composition is heated to sufficiently dry the solvent, and further heated to sufficiently cure the conductive resin composition, as shown in FIG. A shield layer (conductive coating film) 5 is formed on the package surface. The heating conditions at this time can be set as appropriate. FIG. 2 is a plan view showing the substrate in this state. Reference numerals B ₁ , B ₂ ,... B ₉ denote shield packages before being separated into individual pieces, and reference numerals 11 to 19 denote grooves between these shield packages, respectively.

Next, as shown by an arrow in FIG. 1 (e), an individual package B is obtained by cutting the substrate with a dicing saw or the like along the bottom of the groove of the package before the individualization.

The individual package B thus obtained has a uniform shield layer formed on the package surface (all of the upper surface portion, the side surface portion, and the corner portion of the boundary between the upper surface portion and the side surface portion). Good shielding characteristics can be obtained. In addition, since the adhesion between the shield layer and the package surface and the ground circuit is excellent, it is possible to prevent the shield layer from being peeled off from the package surface or the ground circuit due to an impact when the package is separated into pieces by a dicing saw or the like. .

Hereinafter, the content of the present invention will be described in detail based on examples, but the present invention is not limited to the following. In the following description, “part” or “%” is based on mass unless otherwise specified.

[Examples and Comparative Examples]
For the total amount of 100 parts by mass of the following compounds (a1, a2) having two or more maleimide groups in one molecule and thermosetting compounds (b1 to b3), a curing agent, a conductive filler (d ) And a solvent were blended and mixed at a ratio described in Table 1 to obtain a conductive resin composition. The details of each component used are as follows.

Compound (a1): DESIGNER MOLECURES Inc. Product name “BMI-689”, weight average molecular weight = approximately 689
Compound (a2): DESIGNER MOLECURES Inc. Product name “BMI-3000”, weight average molecular weight = approximately 3000

Compound (b1): Liquid glycidylamine epoxy resin, manufactured by ADEKA Corporation, trade name “EP-3905S”
Compound (b2): Liquid glycidyl ether epoxy resin, manufactured by ADEKA Corporation, trade name “EP-4400”
Compound (b3): (meth) acrylate compound, 2-hydroxy-3-acryloyloxypropyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Light Ester G-201P”)

<Curing agent>
Compound having imidazole group (c1): 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name “2E4MZ”)
Compound (c2) having an imidazole group: 2-undecylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name “C11Z”)
Amine-based compound: polyamine-based curing agent (trade name “Fujicure FXR-1030” manufactured by T & K TOKA Co., Ltd.)

Conductive filler (d): Silver-coated copper alloy powder (average particle size = 5 μm, flake shape, aspect ratio = 2-10, tap density = 5.8 g / cm ³ )
Solvent: Methyl ethyl ketone (MEK)

Evaluation of the conductive resin compositions of the above Examples and Comparative Examples was performed as follows. The results are shown in Table 1.

(1) Conductivity of conductive coating film The conductivity of the conductive coating film obtained from the conductive resin composition of Example 1 was evaluated by specific resistance. Specifically, as shown in FIG. 3, the electrode pad 21 formed of copper foil has a thickness of 55 μm provided with a slit having a width of 5 mm on the glass epoxy substrate 20 provided at both ends with an interval of 60 mm. The polyimide film was affixed so that the ends of the slits overlapped with the electrode pads 21 at both ends to form a printing plate. On top of that, the conductive resin compositions obtained in the examples and comparative examples were printed using a metal squeegee. The conductive resin composition is cured by heating at 190 ° C. for 20 minutes, the polyimide film is peeled off, and a cured product 22 having a length of 70 mm, a width of 5 mm, and a thickness of about 40 μm is connected between the electrode pads 21 at both ends. Thus, the substrate 20 formed in the above was obtained. About this cured | curing material sample, the resistance value ((ohm)) between electrode pads was measured using a tester, and specific resistance ((omega | ohm)) by following Formula (1) from cross-sectional area (S, cm < ² >) and length (L, cm). Cm) was calculated.

Regarding the cross-sectional area, length, and specific resistance of the sample, a total of 15 lines were formed by printing 5 lines each on 3 glass epoxy substrates, and the average value was obtained. If the specific resistance is 2 × 10 ⁻⁴ Ω · cm or less, it can be suitably used as a conductive resin composition used for the shield layer.

In addition, the specific resistance was measured in the same manner for other examples and comparative examples.

(2) Adhesiveness of conductive coating (comparison before and after solder dip)
The adhesion between the shield layer and the package surface or the ground circuit was evaluated based on JIS K 5600-5-6: 1999 (cross cut method). Specifically, a copper foil was prepared for evaluation of adhesion to the ground circuit, and a mold resin for evaluation of adhesion to the package surface was prepared. Each is masked with a polyimide tape so as to form an opening having a width of 5 cm and a length of 10 cm, and after spray application of the conductive resin composition using a spray coating apparatus SL-940 (manufactured by Nordson Asymtek) at 190 ° C. It was cured by heating for 20 minutes, and the polyimide tape was peeled off to form a coating film having a thickness of about 15 μm. A cross cut test was performed on the copper foil on which the coating film was formed and the mold resin. The cross-cut test was carried out before reflow and after three reflow treatments at 250 ° C. for 10 seconds.

The evaluation of adhesion was performed according to the following criteria.
0: The edge of the cut is completely smooth and there is no peeling to the eyes of any lattice.
1: Small peeling of the coating film occurs at the intersection of cuts. The cross-cut portion is clearly not affected by more than 5%.
2: The coating film is peeled along the edge of the cut and / or at the intersection. The cross-cut part is clearly affected by more than 5% but not more than 15%.
3: The coating film is partially or completely peeled along the edge of the cut, and / or various parts of the eye are partially or completely peeled off. The cross-cut part is clearly affected by more than 15% but not more than 35%.
4: The coating film is partially or completely peeled along the edge of the cut, and / or some eyes are partially or completely peeled off. It is clearly not more than 35% that the cross-cut is affected.
5: Any of the degree of peeling that cannot be classified even with classification 4.

(3) Discoloration test for conductive coating (measurement of color change before and after heating)
The color tone of the coating film after heat-curing the conductive resin composition of the present invention was evaluated. Specifically, masking is performed using a polyimide tape so as to form an opening having a width of 1.5 cm and a length of 4.0 cm on a glass plate, and conductive using a spray coating apparatus SL-940 (manufactured by Nordson Asymtek). After the spray application of the conductive resin composition, it was cured by heating at 190 ° C. for 20 minutes, and the polyimide tape was peeled off to obtain a cured coating film having a thickness of 20 μm. The color (hue H, lightness V, and saturation C) of the obtained cured coating film was examined according to JIS Z 8721 (1993). Next, these cured coating films were further heated at 200 ° C. for 60 minutes, and the colors of the cured coating films were examined in the same manner as described above. The color after further heating the cured coating film at 200 ° C. for 60 minutes is almost the same as the color of the cured coating film after the heat cycle test (200 cycles of −65 ° C. for 30 minutes and 150 ° C. for 30 minutes). It has been confirmed in advance. The color change was evaluated according to the following criteria.

Pass (◯): Lightness V did not change or was a change of less than two steps (for example, change from V6 to V5).
Fail (x): There were two or more changes in brightness V.

As shown in Table 1, discoloration after heat curing was suppressed in each example, but in Comparative Examples 1 to 3, there were two-level changes in brightness V, and the color was remarkably discolored.

(4) Storage stability of conductive resin composition The content of the solvent of the conductive resin composition obtained in each of the above Examples and Comparative Examples was adjusted to 5% by mass and stored frozen for 3 months. . About the conductive resin composition before frozen storage and after frozen storage, the viscosity of the composition at a temperature of 25 ° C. was measured using a BH viscometer or a conical plate type rotational viscometer. Viscosity measurement with a BH type viscometer 5 was performed at a rotation speed of 10 rpm. Viscosity measurement with a cone-plate rotary viscometer was performed at 0.5 rpm using a programmable viscometer “DV-II + Pro” manufactured by Brookfield, Inc., and a cone spindle CP40.

Based on the amount of change in viscosity before and after freezing, the following criteria were used for evaluation.
Pass (O): The amount of change in viscosity before and after freezing was less than 20%.
Fail (x): The amount of change in viscosity before and after freezing storage was 20% or more.

From the results shown in Table 1, all the coating films obtained from the conductive resin compositions of the examples not only have good conductivity, but also have good adhesion and are difficult to discolor even under severe heating conditions. confirmed. In addition, the storage stability was excellent.

Claims

(A) a compound represented by the following general formula (I), having a molecular weight of 500 to 2000, and having two or more maleimide groups in one molecule;
(B) a thermosetting compound,
(C) A conductive resin composition containing at least a compound having an imidazole group and (D) a conductive filler.

However, in the formula (I), X represents an aliphatic, alicyclic or aromatic hydrocarbon group which is a hydrocarbon group having 10 to 30 carbon atoms in the main chain, and these groups are , A hetero atom, a substituent, or a siloxane skeleton.
The thermosetting compound (B) is
It is at least one selected from the group consisting of epoxy resins that are solid at room temperature, epoxy resins that are liquid at room temperature, and (meth) acrylate compounds.
The conductive resin composition according to claim 1.
The content of the compound (C) having an imidazole group is 0.5 to 50 parts by mass with respect to 100 parts by mass of the total amount of the compound (A) having the maleimide group and the thermosetting compound (B). The conductive resin composition according to claim 1 or 2, wherein
The content of the conductive filler (D) is 200 to 1800 parts by mass with respect to 100 parts by mass of the total amount of the maleimide group-containing compound (A) and the thermosetting compound (B). Item 4. The conductive resin composition according to any one of Items 1 to 3.
The conductive resin composition according to any one of claims 1 to 4, wherein the conductive filler (D) is copper powder, silver-coated copper powder, or silver-coated copper alloy powder.
The conductive resin composition according to any one of claims 1 to 5, which is used for shielding an electronic component package.
A method of manufacturing a shield package in which an electronic component is mounted on a substrate and a package in which the electronic component is sealed with a sealing material is covered with a shield layer,
Mounting a plurality of electronic components on a substrate, sealing the electronic components by filling and curing a sealing material on the substrate, and
Cutting the sealing material between the plurality of electronic components to form grooves, and individualizing the package of each electronic component on the substrate by these grooves;
Applying the conductive resin composition according to any one of claims 1 to 6 to the surface of the individualized package by spraying;
Heating a substrate having a conductive resin composition applied to the surface of the package, and curing the conductive resin composition to form a shield layer;
And obtaining a shield package separated by cutting the substrate along the groove.