# Patent

## Title
Sealant composition for electronic device

## Abstract

The present invention provides a sealant composition for electronic device, in which the curing does not proceed when heated, which does not cause the problem of use in the mounting process of electronic device. The present invention relates to a sealant composition for electronic device comprising (a) a compound having two or more (meth)acryloyl groups and (c) a nitroxide compound and/or a thiocarbonylthio compound.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 14/201,121 filed Mar. 7, 2014, which is a continuation of International Patent Application No. PCT/JP2012/072987 filed Sep. 7, 2012, which claims priority to International Patent Application No. PCT/JP2011/070653, filed Sep. 9, 2011, the contents of all of which are incorporated herein by reference.


FIELD OF THE INVENTION
The present invention relates to a composition to be usable for producing an electronic device, particularly a semiconductor device, and use of the same.
BACKGROUND OF THE INVENTION
As a mounting technology for a semiconductor chip, a flip chip technology, by which a semiconductor chip is directly connected onto a substrate has been known. In the flip chip mounting, a semiconductor chip and a circuit substrate are connected by means of electrodes (bumps) formed on the element formation surface side of the semiconductor chip. On this occasion, for the sake of reinforcement of the bonding parts and enhancement of the reliability of the connections, an underfill sealant, which is an adhesive composition, is generally filled between the semiconductor chip and the wiring substrate.
As an underfill composition, adhesive compositions containing an epoxy-based compound and/or a (meth)acrylic compound or the like have been known (e.g. Japanese Patent Laid-Open No. 2010-226098). Among them, a composition utilizing a radical curing reaction of a (meth)acrylic compound has an advantage over a composition containing an epoxy-based compound that the reaction rate is higher and the efficiency in producing an electronic device can be enhanced.
As a method for filling an underfill sealant, it has been known that a method in which a liquid adhesive composition is first applied on a wiring substrate and then a semiconductor chip is mounted to conduct simultaneously electrode connection and sealing; a method (a so-called capillary method) in which electrical connection between an electrode on a semiconductor chip and a substrate is first established and then a liquid adhesive composition is applied on a side or a plurality of sides of the chip for sealing the gap between the wiring substrate and the semiconductor chip by capillarity and the like. By any of the methods, it is required to apply a liquid adhesive composition all over the wiring substrate, to fill the liquid adhesive composition uniformly in the gap between the semiconductor chip and the wiring substrate, and the like. Therefore, occasionally, a syringe which are used for applying adhesive, the substrate and the like are heated to room temperature or higher as needed in order to increase flowability of the adhesive composition.
However, there has been a problem in that, when an underfill sealant utilizing a radical curing reaction is used, a curing reaction of an underfill composition may occasionally progress prematurely before carrying out sealing, which leads to inadequate electrode connection or poor work efficiency. Such a problem tends to occur when an adhesive composition is in a state at room temperature or higher as described above. In order to overcome the problem, an additive is mixed in an underfill sealant composition or the working temperature is lowered, which has not been sufficient. Consequently, further improvement of an adhesive composition to be used for an electronic device has been sought after.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the aforedescribed problems in using a conventional adhesive composition and to provide a composition which improves productivity of electronic devices. Further, another object is to provide an electronic device or an electronic appliance containing the composition.
The present invention relates to the following items.
1. A sealant composition for electronic device comprising:

    
    
        (a) a compound having two or more (meth)acryloyl groups and
        (c) a nitroxide compound and/or a thiocarbonylthio compound.
    
    


2. The composition according to the above item 1, further comprising a radical initiator.
3. The composition according to the above item 1 or 2, further comprising (b) a maleimide compound.
4. The composition according to the above item 3, wherein the maleimide compound (b) comprises a bismaleimide.
5. The composition according to any one of the above items 1 to 4, which is used as an underfill sealant.
6. The composition according to any one of the above items 1 to 5, which is used in flip chip mounting.
7. An electronic device comprising a cured product of the composition according to any one of the above items 1 to 6.
8. An electronic appliance comprising the electronic device according to the above item 7.
The progress of the curing reaction of a composition according to the present invention at room temperature or higher and 80° C. or lower can be suppressed adequately. Therefore, the progress of curing reaction during flip chip mounting of a semiconductor chip is suppressed, and thus the composition of the present invention does not cause a defective electrode connection during flip chip mounting of a semiconductor chip and sufficient working time in a mounting process can be secured. As the result, a higher quality product can be provided without decreasing the production efficiency of an electronic device by flip chip mounting.


DETAILED DESCRIPTION OF THE INVENTION
A composition for an electronic device according to the present invention contains at least

    
    
        (a) a compound having two or more (meth)acryloyl groups and
        (c) a nitroxide compound and/or a thiocarbonylthio compound. The respective components will be described below.
    
    


<(a) A Compound Having Two or More (meth)acryloyl Groups >
A composition of the present invention comprises a (meth)acrylic compound having two or more (meth)acryloyl groups (hereinafter, referred to as “component (a)”). Ordinarily, it is preferable that a compound having one (meth)acryloyl group and/or a compound having three or more (meth)acryloyl groups is used as needed in addition to a compound having two (meth)acryloyl groups. Further, the (meth)acrylic compound may be a monomer or an oligomer.
Although there is no particular restriction on a (meth)acrylic compound usable for the present invention, examples of monofunctional compounds having a (meth)acryloyl group include phenylphenol acrylate, methoxypolyethylene acrylate, acryloyloxyethyl succinate, a aliphatic acrylate, methacryloyloxyethyl phthalic acid, phenoxyethylene glycol methacrylate, a aliphatic methacrylate, β-carboxyethyl acrylate, isobornyl acrylate, isobutyl acrylate, tert-butyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, dihydrocyclopentadiethyl acrylate, cyclohexyl methacrylate, tert-butyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate, 4-hydroxybutyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethylcarbitol acrylate, phenoxyethyl acrylate, and methoxytriethylene glycol acrylate. Examples of compounds having two or more (meth)acryloyl groups include hexanediol dimethacrylate, hydroxyacryloyloxypropyl methacrylate, hexanediol diacrylate, urethane acrylate, epoxy acrylate, bisphenol A-type epoxy acrylate, modified epoxy acrylate, fatty acid-modified epoxy acrylate, amine-modified bisphenol A-type epoxy acrylate, allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate, tricyclodecane dimethanol dimethacrylate, glycerine dimethacrylate, polypropylene glycol diacrylate, propoxylated ethoxylated bisphenol A diacrylate, 9,9-bis(4-(2-acryloyloxyethoxy)phenyl)fluorene, tricyclodecane diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, propoxylated neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, 1,12-dodecanediol dimethacrylate, trimethylolpropane trimethacrylate, dipentaerythtol polyacrylate, dipentaerythtol hexaacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, polyether triacrylate, glycerine propoxy triacrylate, pentaerythritol tetraacrylate, pentaerythritolethoxy tetraacrylate, ditrimethylol propane tetraacrylate, monopentaerythritol acrylate, dipentaerythritol acrylate, tripentaerythritol acrylate, polypentaerythritol acrylate, and pentaerythritol triacrylate.
Examples of commercial products of a (meth)acrylic compound usable for the present invention include functional monomers of SR&CD series, functional epoxy acrylate oligomers and functional urethane acrylate oligomers of CN series from Sartomer, Co., Inc., Light Ester series, and Light Acrylate series from Kyoeisha Chemical Co., Ltd., and NK Ester from Shin-Nakamura Chemical Co., Ltd.
The (meth)acrylic compounds may be used singly or in a combination of two or more kinds thereof.
The content of a (meth)acrylic compound in accordance with the present invention may be adjusted depending on the purpose of use, and is preferably from 10 to 90% by weight based on the total weight of a compound, and more preferably from 20 to 60% by weight. If the content of a (meth)acrylate is within the range, the viscosity of a composition before curing is low, and is superior in workability, and also in strength after curing.
<(c) Nitroxide Compound and/or thiocarbonylthio Compound>
The composition according to the present invention contains a nitroxide compound and/or a thiocarbonylthio compound (hereinafter, referred to as “component (c)”). A component (c) is a compound generally used as a regulating agent for regulating a growth reaction or a termination reaction in a living radical polymerization.
A nitroxide compound means a compound having a nitroxide radical moiety represented by Formula (II) or a compound which can generate a nitroxide radical moiety. The nitroxide radical moiety of Formula (II) is known as a capping agent for capping a radical at a polymer growing end in a living radical polymerization reaction mediated by nitroxide (NMP: Nitroxide-Mediated radical Polymerization).




Further, a thiocarbonylthio compound has a structure of Formula (III), and is known as a chain transfer agent for a RAFT (Reversible Addition Fragmentation chain Transfer) polymerization reaction, which is a kind of living radical polymerization.




When the composition according to the present invention is used for producing a semiconductor device, the composition is, for example, applied on a wiring substrate as described below. In such an event, the composition is occasionally put in a state at room temperature or higher in order to increase flowability of the composition. On this occasion, since the composition according to the present invention contains a component (c), the progress of the curing reaction is suppressed adequately and the work efficiency at a succeeding mounting process is not decreased. This is because, as presumed by the inventors, radicals generated in the composition inactivate reversibly a growing radical species with the radical structure of a component (c), and the progress of the curing reaction is suppressed thereby. In addition, the composition according to the present invention is not inhibited in the subsequent curing reaction at a higher temperature, and does not cause a problem in physical properties of a cured composition.
The content of a component (c) in the composition according to the present invention is preferably from 0.001 to 5% by weight based on the total weight of the composition, and more preferably from 0.01 to 1% by weight. Further, the composition according to the present invention preferably contains a thermal radical initiator described below, and in this case the molar ratio of an initiator to a component (c) (initiator:component (c)) is preferably from 1:0.001 to 1:10, and more preferably from 1:0.01 to 1:1. If the content of a component (c) is within the range, any problem in the reactivity or physical properties of a composition does not arise.
Although there is no particular restriction on a compound having a nitroxide radical moiety, examples thereof include 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide, 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO), 2,2,6,6-tetraethyl-1-piperidinyloxy radical, 2,2,6,6-tetramethyl-4-oxo-1-piperidinyloxy radical, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy radical, 1,1,3,3-tetramethyl-2-isoindolinyloxy radical, and N,N-di-t-butylaminoxy radical.
Examples of a compound which can generate a nitroxide radical moiety include alkoxyamine compounds represented by the following general Formula (IV):

R1—O—N(R2)(R3)  (IV)

wherein R1, R2, R3 are organic residues, and R2 and R3 may together form a cyclic structure.

Examples of alkoxyamine compounds represented by the general Formula (IV) include the following alkoxyamine compounds as described in the research paper of Didier Benoit, et al. (J. Am. Chem. Soc., 1999, 121, p. 3904 to 3920), and the like.










The above compounds are available as commercial products, for example, from Sigma-Aldrich Co. LLC., and can be also synthesized by a publicly known method.
Examples of a thiocarbonylthio compound include compounds described in Japanese Laid-open Patent Publication No. 2004-518773. Specific examples include, but not limited to, 2-cyano-2-propyl benzodithioate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, 2-cyano-2-propyl dodecyl trithiocarbonate, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid, cyanomethyl dodecyl trithiocarbonate, cyanomethyl methyl(phenyl)carbamodithioate, bis(thiobenzoyl)disulfide, and bis(dodecylsulfanylthiocarbonyl)disulfide. The above are available as commercial products, for example, from Sigma-Aldrich Co. LLC.
The compounds may be used singly or in combinations of two or more of the same as a component (c) for the composition according to the present invention.
<(b) Maleimide Compound>
A composition according to the present invention may preferably contain further a (b) maleimide compound (hereinafter, referred to as “component (b)”) in addition to the (a) (meth)acrylic compound and the (c) nitroxide compound and/or a thiocarbonylthio compound. Although there is no particular restriction on a maleimide compound to be contained in a composition according to the present invention, examples thereof include the following compounds.
A maleimide compound has at least one, preferably one or two following moiety (I) in the molecule.




In the formula, R1 and R2 represent H, or a alkyl group having 1 to 6 carbons; or R1 and R2 together represent an alkylene group having 2 to 6 carbons. Preferably R1 and R2 are both H; or R1 and R2 together represent a 1,4-butylene group.
The maleimide compound is preferably liquid at room temperature and therefore the moiety (I) bonds to a group that allows the maleimide compound to be liquid, for example, an organic group having a branched alkyl, alkylene, alkylene oxide, alkylene carboxyl, or alkylene amide structure having sufficient length and branches to render the maleimide compound liquid. The maleimide compound may have one, or two or more structures (I). The compound having two of these groups is a bismaleimide compound. In addition, a maleimide compound, even if it is not liquid, may be used if the composition becomes liquid as being mixed with another maleimide compound or mixed with another component.
Examples of a maleimide compound, in which the moiety (I) bonds to an alkyl group or an alkylene group (the groups may have a double bond, or a saturated aliphatic ring), include the following compounds.




Particularly preferable examples include stearyl maleimide, oleyl maleimide, biphenyl maleimide, and a 1,20-bismaleimide derivative of 10,11-dioctyleicosane, as well as a combination thereof. A 1,20-bismaleimide derivative of 10,11-dioctyleicosane is available from Henkel AG & Co. under a product name of X-BMI, which is synthesized from 1,20-diamino-10,11-dioctyl-eicosane and/or a diamine of a cyclic isomer thereof by a method according to U.S. Pat. No. 5,973,166 (the entire disclosures of U.S. Pat. No. 5,973,166 are incorporated herein by reference). X-BMI contains one, or two or more of 1,20-bismaleimide-10,11-dioctyl-eicosane [compound denoted by Formula (X-1)], 1-heptylene maleimide-2-octylene maleimide-4-octyl-5-heptylcyclohexane [compound denoted by Formula (X-2)], 1,2-dioctylene maleimide-3-octyl-4-hexylcyclohexane [compound denoted by Formula (X-3)], and the like. Bismaleimide compounds denoted by formulas (X-1) to (X-3) may be also preferably used solely.
Examples of a maleimide compound, in which the moiety (I) is bonded with a group having an alkylene oxide structure, include the following compounds.




In the formula, R is an alkylene group, preferably ethylene or 1,2-propylene, and n is an integer from 2 to about 40, wherein the magnitude of an integer and the distribution of n to render the compound liquid are selected preferably. The compound is available from DIC Corporation as LUMICURE (registered trademark) MIA200.
Examples of another usable maleimide compound include a compound (3,4,5,6-tetrahydrophthaloimide ethyl acrylate) denoted by the following formula.




The above maleimide compounds may be used singly or in a combination of two or more kinds thereof.
The content of a maleimide compound in accordance with the present invention is preferably from 0 to 50% by weight based on the total weight of a composition, more preferably from 0.1 to 50% by weight, and further preferably from 1 to 20% by weight. If the content of a maleimide compound is within the range, the curing rate becomes superior.
Meanwhile, when a composition contains a maleimide compound in accordance with the present invention, the (meth)acrylic compound and the maleimide compound in a composition polymerize by a radical reaction by being heated to a predetermined temperature. In this case, only 1 kind of compound may polymerize to form a homopolymer, or two or more kinds of compounds may polymerize to form a copolymer.
<Filler>
A composition according to the present invention may contain a filler. By blending a filler, a composition for an electronic device having a low coefficient of linear expansion exhibiting superior dimensional stability and improved flame resistance can be obtained. As a filler, either of an insulating inorganic filler or an electrically conductive inorganic filler may be selected depending on the purpose of use. Examples of an insulating inorganic filler include silica, calcium silicate, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, aluminum nitride, and boron nitride, and particularly silica is preferable. Examples of an electrically conductive inorganic filler include a metal and carbon black.
Further, a filler subjected to a surface modification according to need may be also used. Examples of commercial products include a lineup of “Mitsubishi carbon black” from Mitsubishi Chemical Corporation, “Asahi” series from Asahi Carbon Co., Ltd., calcium silicate “PCM Lite” series, aluminum hydroxide “ALH” series, and alumina-based “Celasule” from Kawai Lime Ind. Co., Ltd., titanium oxide “STR series”, silica “Sciqus Series”, zinc oxide “FINEEX series”, magnesium oxide “SMO Series”, and zirconium oxide “STR Series” from Sakai Chemical Industry Co., Ltd., silica, oxidized alumina “ADMAFINE” series from Admatechs Company Limited, silica “SNOWTEX” series from Nissan Chemical Ind., Ltd., and a metallic oxide containing silica and aluminum oxide “NanoTek” series from C.I. Kasei Co., Ltd.
When a composition according to the present invention is used for producing, for example, a semiconductor device, the average particle diameter of a filler is preferably smaller than the gap dimension between a semiconductor chip element formation surface and a wiring substrate. If the average particle diameter of a filler is too large, the filler may be trapped between metal connections in producing a semiconductor device, so that good electrical reliability may not be established, or a chip may break.
Although the blending amount of a filler may be adjustable depending on the purpose of use, it is preferably, for example, from 1 to 99% by weight based on the total weight of an adhesive composition, and more preferably from 10 to 80% by weight. If the content is within the range, a composition having a sufficient effect of filler addition and a viscosity free from any problem in handling can be obtained.
<Radical Initiator>
A composition according to the present invention contains preferably a radical initiator, more preferably a thermal radical initiator. As a thermal radical initiator, an organic peroxide is preferable, and one that generates a radical at a convenient temperature is selected.
Although there is no particular restriction on a radical initiator, examples thereof include diisobutyl peroxide, cumyl peroxyneodecanate, di-n-propyl peroxycarbonate, diisopropyl peroxycarbonate, di-sec-butyl peroxycarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanate, di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, t-hexyl peroxyneodecanate, t-butyl peroxyneodecanate, t-butyl peroxyneoheptanate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl)peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethyl hexanate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexyl peroxy-2-ethyl hexanate, di(4-methyl benzoyl)peroxide, t-butylperoxy-2-ethyl hexanate, dibenzoyl peroxide, 1,1-di(t-butylperoxy)-2-methylcyclohexane, 1,1-di(t-hexylperoxy)-3,3,5-trimethyl cyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane, t-hexylperoxy isopropyl monocarbonate, t-butyl peroxymaleic acid, t-butyl peroxy-3,5,5-trimethyl hexanate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, 2,5-di-methyl-2,5-di(benzoyl peroxy)hexane, t-butyl peroxyacetate, 2,2-di(t-butylperoxy)butane, t-butyl peroxybenzoate, n-butyl-4,4-di-(t-butylperoxy)valerate, di(2-t-butyl peroxyisopropyl)benzene, dicumyl peroxide, di-t-hexyl peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane-3,3,5-diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethyl butyl hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, and 2,3-dimethyl-2,3-diphenyl butane. The organic peroxides can be purchased from Akzo Nobel N.V., Gio specialties Chemical, Arkema S.A., NOF Corporation, Kayaku Akzo Corporation, and the like. The same may be used singly, or in a combination of two or more kinds thereof.
The blending amount of a radical initiator is preferably from 0.01 to 10% by weight based on the total weight of a composition, and more preferably from 0.1 to 5% by weight. If the blending amount of a thermal radical initiator is within the range, there occurs no problem of instability in applying the composition or of prolongation of a curing time.
In addition to the aforedescribed components, a composition according to the present invention may contain an additive as needed, such as a silane coupling agent, a rubber component, an antioxidant, a light stabilizer, a radical stabilizing agent, and a surfactant. A silane coupling agent and a rubber component can advantageously improve the adhesive property of a composition, relax a stress, and reduce warping of a cured reaction product. Meanwhile, an antioxidant, and a radical stabilizing agent may be used in order to extend the pot life. A surfactant may be added for defoaming in coating, or for improving the wettability to a target to be coated and the leveling property.
By blending a silane coupling agent to a composition the adhesive property of an adhesive can be improved.
Although there is no particular restriction on a silane coupling agent, examples thereof include an aminosilane coupling agent, an epoxy silane coupling agent, a ureide silane coupling agent, an isocyanate silane coupling agent, a vinyl silane coupling agent, a (meth)acrylic silane coupling agent, and a ketimine silane coupling agent, and among these, an isocyanate silane coupling agent, a (meth)acrylic silane coupling agent, and an epoxy silane coupling agent are preferable. The silane coupling agents can be purchased from Dow Corning Toray Silicone Co., Ltd., Shin-Etsu Silicone, Matsumoto Fine Chemical Co., Ltd., Tokyo Chemical Industry Co., Ltd. and the like.
Although the blending amount of a silane coupling agent is adjustable appropriately, it is preferably, for example, from 0 to 10% by weight based on the total weight of a composition, and more preferably from 0 to 5% by weight. If the content of a silane coupling agent is too high, a silane coupling agent vaporizes during thermal compression bonding in a flip chip process to develop voids.
Although there is no particular restriction on rubber, examples thereof include industrial rubbers, such as acrylic rubber, nitrile rubber, butadiene rubber, and nitrile butadiene rubber, and a low molecular weight crosslinking agent for rubber. Examples of commercial products for industrial rubbers include “Paracron RP” series from Negami Chemical Industrial Co., Ltd., “Staphyloid IM” series and “Staphyloid AC” series from Ganz Chemical Co., Ltd., “Zeon” series from Zeon Kasei Co., Ltd., and “METABLEN C/E/W/S/SX/SRX” from Mitsubishi Rayon Co., Ltd. Examples of commercial products for a low molecular weight crosslinking agent for rubber include “Ricon” series from Sartomer, “Poly bd” and “Poly ip” series, “EPOL” series, and “Krasol” from Idemitsu Kosan Co., Ltd., and “NISSO-PB” from Nippon Soda Co., Ltd. The products may be used singly or in a combination of two or more kinds thereof.
Further, a commercial product of an acrylic resin, in which a rubber particle has been dispersed in advance, may be used, and examples thereof include Paracron SN-50, AS-3000, ME-2000, W-1163, W-248E, W-197C, PRE-COAT 200, and PANLON S-2012 from Negami Chemical Industrial Co., Ltd.
Although the blending amount of rubber is adjustable appropriately, it is preferably, for example, from 0 to 30% by weight based on the total weight of an adhesive composition, and more preferably from 0 to 20% by weight. If the rubber content is too high, the viscosity of an adhesive composition increases too much causing such problems that the handling property may be deteriorated, or mixing of other components may become difficult, or the adhesiveness of an adhesive may be deteriorated.
Examples include for an antioxidant and a radical stabilizing agent hydroquinones, benzoquinones, and hindered phenols; and for a light stabilizer benzotriazole-based, triazine-based, benzophenone-based, benzoate-based, and hindered amine-based ultraviolet absorbers. A surfactant may be selected out of catalogs of commercial products depending on a purpose of use.
<Production Method of Composition for Electronic Device>
A composition according to the present invention can be obtained by mixing uniformly the above specified respective components, as well as a solvent according to need. A composition is only required that a viscosity thereof is adjusted as long as it can be applied by a coater such as a dispenser, and may be also solventless. It is also possible to adjust viscosity by selection of compounds in a composition, or by adjustment of the blending amounts thereof. A composition according to the present invention can be produced by kneading uniformly predetermined amounts of the respective components by, without limitation thereto, using singly or in a combination of publicly known various kneading machines, such as a homodisperser, a universal mixer, a Banbury mixer, a kneader, a twin roll mill, a triple roll mill, and an extruder. Kneading may be conducted under various conditions, such as at normal temperature or with heating, at a normal pressure, a reduced pressure, or an increased pressure, or with inert gas flow.
The composition for an electronic device according to the present invention is preferably used as a sealant for an electronic device, without particular restriction thereto. In this regard, examples of a sealant include an underfill sealant (sealant) for an electronic device including a semiconductor chip, an insulating varnish, an insulating material for a printed wiring substrate, an impregnation resin for a printed wiring substrate, a coating material for an electronic device, a potting material for an electronic device, and an adhesive for an electronic device. It is particularly preferable that the present invention is directed to use as an underfill sealant.
<Electronic Device and Production Method of the Same>
Next, a production method of an electronic device comprising a composition according to the present invention will be described. Although there is no particular restriction on a production method of an electronic device, a flip chip process is preferably used. In a flip chip process, it is particularly preferable to coat a circuit face of a wiring substrate with a composition according to the present invention. A production method of an electronic device comprises, for example,

    
    
        (1) a coating process for coating a circuit face of a wiring substrate with a composition according to the present invention, and
        (2) a bonding and sealing process for placing a semiconductor chip on the composition applied on the wiring substrate, and performing electrical connection between the semiconductor chip and the wiring substrate and seal of a gap therebetween. The respective processes will be described below.
    
    


<(1) Coating Process>
In the coating process, a composition according to the present invention is applied on a circuit face of a wiring substrate. All over the surface of a wiring substrate or only a part where a semiconductor chip is to be mounted may be coated with the composition. Examples of a coating method include coating methods using a spin coater, a dispenser, a roller, and the like and screen printing. In this connection, a syringe used in the coating process, a substrate, and the like may be heated to room temperature or higher as needed so as to improve the flowability of the composition.
<(2) Bonding and Sealing Process>
In the bonding and sealing process, electrical connection between the semiconductor element and the wiring substrate is performed, and simultaneously a gap between the semiconductor element and the circuit substrate is sealed with a composition according to the present invention to produce an electronic device. Firstly, a semiconductor chip is placed on a part coated with an adhesive composition on a wiring substrate. On this occasion, a circuit face of the wiring substrate (namely, a face coated with the composition in the coating process) and an element formation surface of the semiconductor chip are so aligned that the two face each other. Then, thermal compression bonding is followed. Heating may be performed additionally after the thermal compression bonding in order to cure the adhesive composition. In general, as a method for thermal compression bonding and connection, thermal compression bonding is performed immediately after position adjustment using a flip chip bonder, or after position adjustment and provisional mounting, heating connection is performed in a reflow oven, and the like. On this occasion, a thermal profile suitable for a package or a sealing method is applied. Further, for chip mounting, not only a flip chip bonder, a die bonder, and the like, with which position adjustment is possible, may be also used alternatively.
There is no particular restriction on the temperature for thermal compression bonding. When an electrode is a solder bump or a solder cap bump, a temperature higher than the melting point by 10 to 100° C. is preferable, 200° C. or higher is preferable, and 210 to 300° C. is more preferable. The duration time for thermal compression bonding is preferably from 1 to 20 sec, and the pressure is preferably from 0.1 to 7 MPa. Further, if additional heating is performed for curing completely an adhesive composition after the thermal compression bonding, for example, 150 to 220° C. for 30 to 180 min are preferable.
An electronic device obtained as above can be applied to various electronic appliances utilizing a semiconductor chip, such as a cell phone, a personal computer, and a TV.
EXAMPLES
The present invention will be described below in more details by way of Examples. However, the present invention is not restricted by the following Examples.
Table 1 shows compounds used in the following Examples and Comparative Examples.









TABLE 1





Component
Name of source material
Description of compound







(Meth)acrylate
CN120 (produced by Sartomer)
Epoxy acrylate oligomer



SR9003 (produced by Sartomer)
Propoxylated neopentyl glycol diacrylate



SR480 (produced by Sartomer)
Ethoxylated bisphenol A dimethacrylate



SR444 (produced by Sartomer)
Pentaerythritol triacrylate


Maleimide
LUMICURE MIA200 produced by DIC Corporation
Polyalkylene maleimide acetate


Thermal radical
Perbutyl Z (produced by NOF Corporation)
t-butyl peroxybenzoate


initiator




Filler
SE-2030 (produced by Admatechs Co., Ltd.)
Silica


Coupling agent
KBM-503 (produced by Shin-Etsu Chemical Co., Ltd.)
3-Methacryloxypropyltrimethoxysilane


Nitroxide radical 
N-1 (Produced by Sigma-Aldrich Co. LLC.)
N-tert-butyl-N-(2-methyl-1-phenylpropyl)-O-(1-


compound

phenylethyl)hydroxylamine




(compound represented by Formula V)



N-2 (Produced by Sigma-Aldrich Co. LLC.)
2,2,5-Trimethyl-4-phenyl-3-azahexane-3-nitroxide



N-3 (Produced by Sigma-Aldrich Co. LLC.)
TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy radical)


Thiocarbonylthio
S-1 (Produced by Sigma-Aldrich Co. LLC.)
2-Cyano-2-propyl benzodithioate


radical compound
S-2 (Produced by Sigma-Aldrich Co. LLC.)
4-Cyano-4-(phenylcarbonothioylthio)pentanoic acid



S-3 (Produced by Sigma-Aldrich Co. LLC.)
2-Cyano-2-propyl dodecyl trithiocarbonate



S-4 (Produced by Sigma-Aldrich Co. LLC.)
4-Cyano-4-




[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid



S-5 (Produced by Sigma-Aldrich Co. LLC.)
2-(Dodecyithiocarbonothioylthio)-2-methylpropionic acid



S-6 (Produced by Sigma-Aldrich Co. LLC.)
Cyanomethyl dodecyl trithiocarbonate



S-7 (Produced by Sigma-Aldrich Co. LLC.)
Cyanomethyl methyl(phenyl)carbamodithioate



S-8 (Produced by Sigma-Aldrich Co. LLC.)
Bis(thiobenzoyl) disulfide



S-9 (Produced by Sigma-Aldrich Co. LLC.)
Bis(dodecylsulfanylthiocarbonyl) disulfide


Polymerization
Benzoquinone (Produced by Tokyo Chemical Industry



inhibitor
Co., Ltd.)




Hydroquinone (Produced by Tokyo Chemical Industry




Co., Ltd.)









Apparatus, and the like used in the following Examples and Comparative Examples are as follows:

    
    
        (1) Circuit substrate: WALTS-KIT MB50-0102JY_CR from Walts Co., Ltd. Pads are according to CuOSP specifications.
        (2) Semiconductor chip: WALTS-TEG MB50-0101JY with 544 bumps constituted with a Cu pillar and solder from Walts Co., Ltd.

(The circuit substrate (1) and the semiconductor chip (2) are connected together to form a daisy chain, and when all the bumps in a chip are connected, the continuity can be established. In other words, if a single bump out of 544 bumps cannot be connected, electrical insulation is recognized by an electrical continuity test.)

    
    


<Preparation of Adhesive Composition for Underfill Sealant>
The relevant components were mixed by the following method to prepare an adhesive composition. Table 2 shows compounds blended in the respective Examples and Comparative Examples and the blending amounts thereof (% by weight).









TABLE 2








Example
Comparative Example

























1
2
3
4
5
6
7
8
9
10
11
12
13
1
2
3
4




























(Meth)acrylic
CN120
5
5
5
5
5
5
5
5
5
5
5
5
15
6.1
5.1
5
5


compound
SR9003
10
10
10
10
10
10
10
10
10
10
10
10
10
13
10
10
10


(Component 
SR480
10
10
10
10
10
10
10
10
10
10
10
10
10
13
10
10
10


(a))
SR444
10
10
10
10
10
10
10
10
10
10
10
10
13
10
10
10
10


Maleimide
MIA200
10
10
10
10
10
10
10
10
10
10
10
10
0
0
10
10
10


compound




















(Component




















(b))




















Coupling 
KBM-503
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3


agent




















Filler
SE2030
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4
54.4


Radical 
Perbutyl Z
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2


initiator




















Radical 
N-1
0.1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


stabilizer
N-2
0
0.1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


(Component
N-3
0
0
0.1
0
0
0
0
0
0
0
0
0
0
0
0
0
0


(c))
S-1
0
0
0
0.1
0
0
0
0
0
0
0
0
0
0
0
0
0



S-2
0
0
0
0
0.1
0
0
0
0
0
0
0
0
0
0
0
0



S-3
0
0
0
0
0
0.1
0
0
0
0
0
0
0
0
0
0
0



S-4
0
0
0
0
0
0
0.1
0
0
0
0
0
0
0
0
0
0



S-5
0
0
0
0
0
0
0
0.1
0
0
0
0
0
0
0
0
0



S-6
0
0
0
0
0
0
0
0
0.1
0
0
0
0
0
0
0
0



S-7
0
0
0
0
0
0
0
0
0
0.1
0
0
0
0
0
0
0



S-8
0
0
0
0
0
0
0
0
0
0
0.1
0
0
0
0
0
0



S-9
0
0
0
0
0
0
0
0
0
0
0
0.1
0.1
0
0
0
0


Polymer-
Benzo-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.1
0


ization
quinone



















inhibitor
Hydro-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.1



quinone



















Total

100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100





(The unit of the number is weight %.)






Example 1
(Preparation of Composition)
Compounds listed in Table 2 were weighed out according to the designated blending amounts and kneaded uniformly by a triple roll mill. The product was degassed in vacuum to prepare an adhesive composition A.
After heating a circuit substrate in an oven at 120° C. for 1 hour, the composition A was applied on a circuit substrate with an autodispenser to obtain a circuit substrate B coated with the adhesive composition A.
(Mounting of Electronic Device)
Immediately after preparation of the circuit substrate B (heat exposure time 0 min), or after being left standing on a hot plate at 80° C. for 15 min, 30 min, 45 min, 60 min, or 90 min, the position of a semiconductor chip and the circuit substrate B was adjusted and the two were pressed together using a flip chip bonder equipped with a pulse heat function, followed by thermal compression bonding with pulse heating at 240° C. Thereafter, the composition A was cured in an oven at 150° C. for 1 hour to complete an electronic device C.
(Electrical Continuity Test)
The electrical continuity of the above produced electronic device C was examined to find that the electrical continuity was good with respect to any heat exposure time on the hot plate at 80° C. (Table 3). Namely, all of the 544 bumps on the semiconductor chip were connected. Therefore, it was demonstrated that the composition in Example 1 maintained liquidity sufficient for processing, even if the same was left standing on a hot plate at 80° C.










TABLE 3







Time for being left
Electrical continuity









 0 minutes
good



15 minutes
good



30 minutes
good



45 minutes
good



60 minutes
good



90 minutes
good










Examples 2 to 13
Electronic devices were produced by the same method as in Example 1, except that the components to be blended in the compositions were changed as shown in Table 2. Also in Examples 2 to 13, circuit substrates coated with the compositions were left standing at 80° C. for 0 min, 15 min, 30 min, 45 min, 60 min, and 90 min, then electronic devices were produced, and the electrical continuity thereof were examined. As the results, for all the cases, good electrical continuity was obtained. Therefore, it was demonstrated that the compositions in Examples 2 to 13 also maintained liquidity sufficient for processing, even if the same were left standing on a hot plate at 80° C.
Comparative Example 1
An electronic device was produced by the same method as in Example 1, except that the components to be blended in a composition were changed as shown in Table 2 and a maleimide compound and component (c) were not blended. Also in Comparative Example 1, circuit substrates coated with the composition were left standing at 80° C. for 0 min, 15 min, 30 min, 45 min, 60 min, and 90 min, then electronic devices were produced, and the electrical continuity thereof were examined. As the results, good electrical continuity of an electronic device produced without being left standing at 80° C. (heat exposure time 0 min) was confirmed, however in all other cases, electrical continuity was not established (Table 4). Therefore, it was demonstrated that curing of the composition in Comparative Example 1 had progressed by being left standing at 80° C., and good electrical continuity could not be established.










TABLE 4







Time for being left
Electrical continuity









 0 minutes
good



15 minutes
unconnected



30 minutes
unconnected



45 minutes
unconnected



60 minutes
unconnected



90 minutes
unconnected










Comparative Example 2
An electronic device was produced by the same method as in Example 1, except that the components to be blended in a composition were changed as shown in Table 2 and component (c) was not blended. Also in Comparative Example 2, the electrical continuity was examined as in Example 1. As the results, good electrical continuity of an electronic device produced without being left standing at 80° C. (heat exposure time 0 min) was confirmed, however in all other cases (left standing at 80° C.), electrical continuity was not established. It was confirmed that curing of the composition in Comparative Example 2 had also progressed by being left standing at 80° C., and good electrical continuity could not be established.
Comparative Example 3
An electronic device was produced by the same method as in Example 1, except that the components to be blended in a composition were changed as shown in Table 2 and component (c) was replaced with benzoquinone which is a polymerization inhibitor. Also in Comparative Example 3, the electrical continuity was examined as in Example 1. As the results, good electrical continuity of an electronic device produced without being left standing at 80° C. (heat exposure time 0 min) was confirmed, however in all other cases (left standing at 80° C.), electrical continuity was not established. It was confirmed that curing of the composition in Comparative Example 3 had progressed by being left standing at 80° C., and good electrical continuity could not be established.
Comparative Example 4
An electronic device was produced by the same method as in Example 1, except that the components to be blended in a composition were changed as shown in Table 2 and component (c) was replaced with hydroquinone which is a polymerization inhibitor. Also in Comparative Example 4, the electrical continuity was examined as in Example 1. As the results, good electrical continuity of an electronic device produced without being left standing at 80° C. (heat exposure time 0 min) was confirmed, however in all other cases (left standing at 80° C.), electrical continuity was not established. It was confirmed that curing of the composition in Comparative Example 4 had progressed by being left standing at 80° C., and good electrical continuity could not be established.

## Claims

1. A sealant composition for an electronic device comprising:
(a) a compound having two or more (meth)acryloyl groups selected from the group consisting of:
hexanediol dimethacrylate, hydroxyacryloyloxypropyl methacrylate, hexanediol diacrylate, urethane acrylate, epoxy acrylate, bisphenol A-type epoxy acrylate, modified epoxy acrylate, fatty acid-modified epoxy acrylate, amine-modified bisphenol A-type epoxy acrylate, allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate, tricyclodecane dimethanol dimethacrylate, glycerine dimethacrylate, polypropylene glycol diacrylate, propoxylated ethoxylated bisphenol A diacrylate, 9,9-bis(4-(2-acryloyloxyethoxy)phenyl)fluorene, tricyclodecane diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, propoxylated neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, 1,12-dodecanediol dimethacrylate, trimethylolpropane trimethacrylate, dipentaerythtol polyacrylate, dipentaerythtol hexaacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, polyether triacrylate, glycerine propoxy triacrylate, pentaerythritol tetraacrylate, pentaerythritolethoxy tetraacrylate, ditrimethylol propane tetraacrylate, monopentaerythritol acrylate, dipentaerythritol acrylate, tripentaerythritol acrylate, polypentaerythritol acrylate, and pentaerythritol triacrylate,
(b) 1 -20% by weight of a bismaleimide,

and
(c) a nitroxide compound and/or a thiocarbonylthio compound.

2. The composition according to claim 1, further comprising a radical initiator.

3. The composition according to claim 1, which is used as an underfill sealant.

4. The composition according to claim 1, which is used in flip chip mounting.

5. An electronic device comprising a cured product of the composition according to claim 1.

6. An electronic appliance comprising the electronic device according to claim 5.

7. A nonconductive curable sealant composition for an electronic device comprising:
(a) a compound having two or more (meth)acryloyl groups, selected from the group consisting of:
hexanediol dimethacrylate, hydroxyacryloyloxypropyl methacrylate, hexanediol diacrylate, urethane acrylate, epoxy acrylate, bisphenol A-type epoxy acrylate, modified epoxy acrylate, fatty acid-modified epoxy acrylate, amine-modified bisphenol A-type epoxy acrylate, allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate, tricyclodecane dimethanol dimethacrylate, glycerine dimethacrylate, polypropylene glycol diacrylate, propoxylated ethoxylated bisphenol A diacrylate, 9,9-bis(4-(2-acryloyloxyethoxy)phenyl)fluorene, tricyclodecane diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, propoxylated neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, 1,12-dodecanediol dimethacrylate, trimethylolpropane trimethacrylate, dipentaerythtol polyacrylate, dipentaerythtol hexaacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, polyether triacrylate, glycerine propoxy triacrylate, pentaerythritol tetraacrylate, pentaerythritolethoxy tetraacrylate, ditrimethylol propane tetraacrylate, monopentaerythritol acrylate, dipentaerythritol acrylate, tripentaerythritol acrylate, polypentaerythritol acrylate, and pentaerythritol triacrylate,

(b) 1 -20% by weight of a bismaleimide compound;
(c) a nitroxide compound selected from the group consisting of 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide, 2,2,6,6-tetramethyl-1-piperidinyloxy radical, 2,2,6,6-tetraethyl-1-piperidinyloxy radical, 2,2,6,6-tetramethyl-4-oxo-1-piperidinyloxy radical, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy radical, 1,1,3,3-tetramethyl-2-isoindolinyloxy radical, and N,N-di-t-butylaminoxy radical;
(d) a thermal radical initiator;
(e) an electrically insulating inorganic filler;
wherein upon heat exposure of 80° C. for 15 minutes, the composition maintains processibility prior to curing.

8. The nonconductive curable sealant composition of claim 7 wherein the composition is solventless.

9. A nonconductive curable sealant composition for an electronic device comprising:
(a) a compound having two or more (meth)acryloyl groups selected from the group consisting of:
hexanediol dimethacrylate, hydroxyacryloyloxypropyl methacrylate, hexanediol diacrylate, urethane acrylate, epoxy acrylate, bisphenol A-type epoxy acrylate, modified epoxy acrylate, fatty acid-modified epoxy acrylate, amine-modified bisphenol A-type epoxy acrylate, allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate, tricyclodecane dimethanol dimethacrylate, glycerine dimethacrylate, polypropylene glycol diacrylate, propoxylated ethoxylated bisphenol A diacrylate, 9,9-bis(4-(2-acryloyloxyethoxy)phenyl)fluorene, tricyclodecane diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, propoxylated neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, 1,12-dodecanediol dimethacrylate, trimethylolpropane trimethacrylate, dipentaerythtol polyacrylate, dipentaerythtol hexaacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, polyether triacrylate, glycerine propoxy triacrylate, pentaerythritol tetraacrylate, pentaerythritolethoxy tetraacrylate, ditrimethylol propane tetraacrylate, monopentaerythritol acrylate, dipentaerythritol acrylate, tripentaerythritol acrylate, polypentaerythritol acrylate, and pentaerythritol triacrylate;
(b) 1 -20% by weight of a bismaleimide compound;
(c) a thiocarbonylthio compound selected from the group consisting of 2-cyano-2-propyl benzodithioate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, 2-cyano-2-propyl dodecyl trithiocarbonate, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid, cyanomethyl dodecyl trithiocarbonate, cyanomethyl methyl(phenyl)carbamodithioate, bis(thiobenzoyl) disulfide, and bis(dodecylsulfanylthiocarbonyl) disulfide;
(d) a thermal radical initiator;
(e) an electrically insulating inorganic filler;
wherein upon heat exposure of 80° C. for 15 minutes, the composition maintains processibility prior to curing.

10. The composition of claim 9, wherein the composition is solventless.