HK1170514B - Epoxy resin composition - Google Patents

Description

Epoxy resin composition

The present application is a divisional application of application having application date of 2008/3/18, application number of 200880103280.1, and title of "epoxy resin composition".

Technical Field

The present invention relates to an epoxy resin composition containing a novel thermal cationic polymerization initiator and a connection structure formed by joining a wiring board and an electronic component using the composition.

Background

Conventionally, a photo cation polymerizable epoxy resin composition has been used as one of adhesives used for mounting electronic components such as IC chips on a substrate. A photocationic polymerization initiator that generates protons by light and initiates cationic polymerization can be blended in such a photocationic polymerizable epoxy resin composition, and a sulfonium antimonate complex is known as such a photocationic polymerization initiator.

However, since the sulfonium antimonate complex has SbF in which a fluorine atom is bonded to metallic antimony₆ ^-As a counter anion, a large amount of fluorine ions are generated at the time of cationic polymerization, causing migration between different metals, resulting in a problem of corrosion of metal wiring and connection pads. For this reason, it has been proposed to use, as a cationic polymerization initiator, a sulfonium borate complex using a tetrakis (pentafluorophenyl) borate anion [ (C) wherein a fluorine atom and a carbon atom are bonded₆F₅)₄B^-]Replace SbF₆ ^-(patent document 1) actually, a complex of the following formula (1c) [ p-hydroxyphenyl-benzyl-methylthioninium tetrakis (pentafluorophenyl) borate]Are already on the market.

[ solution 1]

However, in many cases, when an electronic component is mounted on a wiring board, light cannot be irradiated to a bonding portion. For this reason, it has been attempted to use the sulfonium borate complex disclosed in the examples of patent document 1 in a thermal cationic polymerization initiator for a thermal cationic polymerizable epoxy resin composition. In this case, it is not only desired to reduce the amount of fluorine ions generated during cationic polymerization to improve the electrical corrosion resistance of the epoxy resin composition, but also desired to improve the low-temperature rapid curability of the epoxy resin composition in order to improve productivity.

Patent document 1: japanese unexamined patent publication No. 9-176112

Disclosure of Invention

Problems to be solved by the invention

However, when the complex of the formula (1c) is used as a thermal cationic polymerization initiator for an epoxy resin composition, the amount of fluorine ions generated during thermal cationic polymerization can be reduced to some extent to improve the resistance to electrolytic corrosion, but the low-temperature rapid curability of the epoxy resin composition is not sufficient.

The present invention has been made to solve the above-mentioned problems occurring in other technologies, and an object of the present invention is to provide an epoxy resin composition which can improve the electric corrosion resistance by reducing the amount of fluorine ions generated during thermal cationic polymerization and has excellent low-temperature curability.

Means for solving the problems

The present inventors have found that the above object can be achieved by using a novel sulfonium borate complex having a specific novel combination of three substituents as a thermal cationic polymerization initiator for an epoxy resin composition, and have completed the present invention.

That is, the present invention provides an epoxy resin composition comprising an epoxy resin and a thermal cationic polymerization initiator, wherein the thermal cationic polymerization initiator is a sulfonium borate complex represented by formula (1).

[ solution 2]

In the formula (1), R₁Is aralkyl, R₂Is lower alkyl. But R is₂When it is methyl, R₁Is not benzyl. X is a halogen atom, and n is an integer of 1 to 3.

In addition, the present invention provides a connection structure in which an electronic component is bonded to a wiring board by a thermosetting product of the epoxy resin composition.

Effects of the invention

The epoxy resin composition of the present invention uses a novel sulfonium borate complex represented by formula (1) as a thermal cationic polymerization initiator in an epoxy resin. This reduces the amount of fluorine ions generated during thermal cationic polymerization, improves the resistance to electrolytic corrosion, and realizes low-temperature rapid curability.

Drawings

[ FIG. 1] A]FIG. 1 is a schematic view of a sulfonium borate complex of reference example 1¹H-NMR spectrum.

[ FIG. 2]]FIG. 2 is a schematic view of a sulfonium borate complex of reference example 2¹H-NMR spectrum.

Detailed Description

The epoxy resin composition of the present invention contains an epoxy resin and a novel sulfonium borate complex represented by formula (1) as a thermal cationic polymerization initiator.

[ solution 3]

In the formula (1), R₁As the aralkyl group (b), there may be mentioned: benzyl, o-methylbenzyl, (1-naphthyl) methyl, pyridylmethyl, anthracenylmethyl, and the like. Among them, (1-naphthyl) methyl is preferable from the viewpoint of good rapid curability and ease of handling.

R₂Examples of the lower alkyl group of (2) include: methyl, ethyl, propyl, butyl, and the like. Among them, methyl is preferable from the viewpoint of good rapid curability and ease of handling. But R is₂When the lower alkyl group of (A) is methyl, the aforementioned R₁Is not benzyl.

N, which represents the number of hydroxyl groups of the phenyl group bonded to the sulfonium residue, is an integer of 1 to 3. When n is 1, it is 4-hydroxyphenyl, 2-hydroxyphenyl or 3-hydroxyphenyl, when n is 2, it is 2, 4-dihydroxyphenyl, 2, 6-dihydroxyphenyl, 3, 5-dihydroxyphenyl, 2, 3-dihydroxyphenyl or the like, and when n is 3, it is 2, 4, 6-trihydroxyphenyl, 2, 4, 5-trihydroxyphenyl, 2, 3, 4-trihydroxyphenyl or the like. Among them, from the viewpoint of excellent rapid curability and ease of handling, a 4-hydroxyphenyl group in which n is 1 and a hydroxyl group is bonded in the para position is preferable.

The halogen atom of X is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Among them, fluorine atoms having a high electron-withdrawing property are preferable from the viewpoint of improving reactivity.

In the epoxy resin composition of the present invention, the novel sulfonium borate complex represented by formula (1) used as a thermal cationic polymerization initiator can be produced according to the following reaction formula. Further, in the formula (1), (2) or (3), R₁Is aralkyl, R₂Is a lower alkyl group, X is a halogen atom, and n is an integer of 1 to 3.

[ solution 4]

< reaction formula >

That is, the sulfonium antimonate complex of formula (2) (see Japanese unexamined patent publication No. 10-245378 for a synthetic method) is dissolved in an organic solvent such as ethyl acetate, an aqueous solution of a sodium borate salt of formula (3) (see Japanese unexamined patent publication No. 10-310587 for a synthetic method) is mixed in an equimolar amount to the solution, and the resulting 2-layer system mixture is stirred at a temperature of 20 to 80 ℃ for 1 to 3 hours to react the sulfonium antimonate complex of formula (2) with the sodium borate of formula (3), thereby obtaining the sulfonium borate complex of formula (1). The sulfonium borate complex of formula (1) can be isolated by separating and drying the organic solvent layer, and then removing the organic solvent by distillation under reduced pressure to obtain the desired product in the form of an evaporation residue.

The epoxy resin constituting the epoxy resin composition of the present invention may be a thermosetting epoxy resin used for bonding conventional electronic materials. Such an epoxy resin may be liquid or solid, and is preferably an epoxy resin having an epoxy equivalent of usually about 100 to 4000 and 2 or more epoxy groups in the molecule. For example, bisphenol A type epoxy compounds, novolak type epoxy compounds, cresol novolak type epoxy compounds, ester type epoxy compounds, alicyclic type epoxy compounds, and the like can be preferably used. Further, these compounds contain monomers or oligomers.

In the epoxy resin composition of the present invention, the blending amount of the sulfonium borate complex of formula (1) is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, because if it is too small, curing is insufficient, and if it is too large, storage stability is deteriorated, relative to 100 parts by mass of the epoxy resin.

In the epoxy resin composition of the present invention, in addition to the above-mentioned thermosetting epoxy resin, a thermosetting resin such as a thermosetting urea resin, a thermosetting melamine resin, or a thermosetting phenol resin, or a thermoplastic resin such as a polyester resin or a urethane resin may be used in combination within a range in which the effect of the present invention is not impaired.

The epoxy resin composition of the present invention may contain, as required, fillers such as silica and mica, pigments, antistatic agents, silane coupling agents, and the like. The epoxy resin composition of the present invention may be used in the form of a solution, paste or film formed by dissolving in a solvent such as toluene.

The epoxy resin composition of the present invention can be prepared by mixing and stirring an epoxy resin, a thermal cationic polymerization initiator, and if necessary, other additives such as a silane coupling agent, a thermosetting resin, and a filler by a conventional method.

The epoxy resin composition of the present invention thus obtained uses a novel sulfonium borate complex as a thermal cationic polymerization initiator, and therefore, in the thermal cationic polymerization, the amount of fluorine ions generated is reduced, the electrical corrosion resistance is improved, and low-temperature rapid curability is achieved.

Therefore, the epoxy resin composition of the present invention can be preferably used in the case of mounting an electronic component on a wiring board. In this case, a connection structure excellent in electrocorrosion resistance, which is formed by connecting an electronic component to a wiring board through a thermosetting product of the epoxy resin composition, can be obtained. This connection structure is also part of the invention.

Examples of the wiring substrate include: flexible printed circuit boards, glass epoxy substrates, glass substrates, tape substrates, and the like. Examples of the electronic component include: an IC chip, a resistive element, a capacitor element, an antenna element, a switching element, and the like.

The thermal cationic polymerization of the epoxy resin composition (paste, film shape, etc.) of the present invention can be carried out by heating to 100 to 250 ℃.

Examples

Reference examples 1, 2 and 3

The sulfonium antimonate complexes of the formulae (1d), (1e) and (1f) (see Japanese unexamined patent publication No. H10-245378 for a synthetic method) were dissolved in ethyl acetate to prepare 10 mass% ethyl acetate solutions of the complexes, respectively. A10 mass% aqueous solution of the sodium borate salt of the formula (3) (see Japanese unexamined patent publication No. Hei 10-310587 for synthesis) was prepared separately.

Then, a 10 mass% aqueous solution of an equimolar amount of the sodium borate salt of the formula (3) was mixed with a 10 mass% ethyl acetate solution of the complex at room temperature, and the mixture was stirred for 30 minutes as it was. Then, the ethyl acetate layer was separated from the reaction mixture, dried, and ethyl acetate was removed under reduced pressure. The sulfonium borate complex of the formula (1a) of reference example 1, the sulfonium borate complex of the formula (1b) of reference example 2 and the sulfonium borate complex of (1c) of reference example 3 were obtained in the form of an evaporation residue.

[ solution 5]

The sulfonium borate complexes of the formulae (1a) and (1b) as the novel compounds were subjected to mass analysis (measuring instrument: AQUITY UPLC System, WATERS Co.), elemental analysis (measuring instrument: PHOENYX, EDAX Co.), IR measurement (measuring instrument: 7000eFT-IR, VARIAN Co.), and the like,¹H-NMR analysis (measuring apparatus: MERCURY PLUS, VARIAN Co.). From the obtained results, it was confirmed that it was the target compound.

The analysis result of the sulfonium borate complex of the formula (1a) [ 4-hydroxyphenyl-methyl-1-naphthylmethyl sulfonium tetrakis (pentafluorophenyl) borate ]

< MS analysis results >

M⁺281 (sulfonium residue)

M⁺679 (Borate residue)

< results of elemental analysis >

Measured value C; 52.51H; 1.89

A theoretical value C; 52.52H; 1.78

<IR analysis result (cm)^-1)>

662(C-S)、776、980、1088、1276(Ar-F)、1300、1374、1464、1514、1583、1643、2881(C-H)、2981(C-H)、3107(O-H)

<¹Results (values) of H-NMR analysis, see FIG. 1 (using THF)>

2.6(1H、(d))、3.3(3H、(a))、5.3(2H、(e))、6.9(2H、(c))、7.6(2H、(b))、7.2～8.1(7H、(f)，(g)，(h)，(i)，(j)，(k)，(l))

[ solution 6]

(proton assignment)

Analysis result of sulfonium borate Complex [ 4-hydroxyphenyl-methyl- (2-methylbenzyl) sulfonium tetrakis (pentafluorophenyl) borate ] of formula (1b)

< MS analysis results >

M⁺245 (sulfonium residue)

M⁺679 (Borate residue)

< results of elemental analysis >

Measured value C; 50.39H; 1.77

A theoretical value C; 50.60H; 1.80

<IR analysis result (cm)^-1)>

662(C-S)、773、980、1088、1276(Ar-F)、1463、1514、1583、1644、2882(C-H)、2983(C-H)、3109(O-H)

<¹Results (values) of H-NMR analysis, see FIG. 2 (using THF)>

2.3(3H、(j))、2.4(1H、(d))、3.3(3H、(a))、4.8(2H、(e))、7.0(2H、(c))、7.6(2H、(b))、7.0～7.4(4H、(f)，(g)，(h)，(i))

[ solution 7]

(proton assignment)

(evaluation of formation of fluorine ion of Complex)

The amounts of fluorine ions generated under temperature conditions during thermal cationic polymerization were measured for the sulfonium borate complexes of reference examples 1 to 3 and each of the sulfonium antimonate complexes of formulae (1d), (1e) and (1 f). That is, 0.2g of each complex was put into 10mL of pure water, heated at 100 ℃ for 10 hours, and then the amount of fluoride ion in the supernatant was measured by ion chromatography (ダイオニクス Co.). The results obtained are shown in table 1. From a practical point of view, less than 10ppm is desirable.

[ Table 1]

Complex compounds	Amount of fluorine ion generated (ppm)
		Sulfonium borate complex (1a)	2.1
Sulfonium borate complex (1b)	2.3
		Sulfonium borate Complex (1c)	2.3
Sulfonium antimonate complex (1d)	160000
		Sulfonium antimonate complex (1e)	170000
Sulfonium antimonate complex (1f)	172000

As is clear from table 1, the sulfonium borate complex exhibits a very small amount of fluorine ion generation, and is useful as a thermal cationic polymerization initiator in this point.

Examples 1 to 4 and comparative examples 1 to 8

The components having the compositions shown in table 2 were uniformly mixed to prepare epoxy resin compositions. As described below, the respective epoxy resin compositions were subjected to differential thermal analysis (DSC measurement) and also to electrocorrosion resistance measurement.

< DSC measurement >

The epoxy resin composition was subjected to differential thermal analysis (heat release initiation temperature, peak temperature, heat release amount) at a temperature rise rate of 10 ℃/min using a thermal analyzer (DSC 5100, セイコ - インスツル Co.). The results obtained are shown in table 2.

The exothermic start temperature is a temperature at which protons are generated from the complex and cationic polymerization starts. The lower the heat release initiation temperature, the higher the low-temperature curability, but the storage stability tends to decrease, so from the practical viewpoint, 60 to 110 ℃ is preferable. When the exothermic peak temperature is too low, the storage stability tends to be low, and when too high, the curing tends to be poor, so that it is preferably 100 to 140 ℃ from the practical viewpoint. The exothermic amount is the heat of reaction, and if the exothermic amount is too small, curing tends to be poor, so that it is generally desired to be 100J/g or more, depending on the epoxy resin used.

< Corrosion resistance test (migration test) >

An epoxy resin composition to be tested was applied to a glass wiring substrate in which an Al/Cr/ITO electrode or a Mo/ITO electrode was formed in a grid-like manner on a glass substrate with a gap of 20 μm, and the thickness of the epoxy resin composition was 20 μm, and the epoxy resin composition was heated at 200 ℃ for 10 minutes to cure the epoxy resin composition, thereby obtaining a test piece. The obtained test piece was placed in a thermostatic bath at 85 ℃ and 85% RH, and left for 12 hours with a voltage of 30V applied between the electrodes. Then, whether discoloration, defects, disconnection, and the like occurred on the electrodes was observed from the front and back surfaces of the glass wiring substrate using an optical microscope, and evaluated according to the following criteria. The obtained results are shown in Table 2.

Evaluation standard of electric corrosion resistance

G: no discoloration, defect, disconnection, etc

NG: visible discoloration, defects, disconnection, etc

Since the epoxy resin compositions of examples 1 to 4 each used the novel sulfonium borate complex represented by the formula (1) or (2), the reaction initiation temperature in DSC measurement was in the range of 60 to 110 ℃, the exothermic peak temperature was in the range of 100 to 140 ℃, the exothermic amount was 100J/G or more, and the evaluation of the electrocorrosion resistance was G, which was practically satisfactory.

In contrast, in comparative examples 1 and 2 in which a complex different from that of the examples was used, there was a problem in the evaluation items of the heat release initiation temperature and the heat release peak temperature, in comparative examples 3 to 6, there was a problem in the evaluation items of the electric corrosion resistance, and in comparative examples 7 and 8, there was a problem in the evaluation items of the heat release initiation temperature, the heat release peak temperature and the electric corrosion resistance.

Industrial applicability

The epoxy resin composition of the present invention uses a novel sulfonium borate complex represented by formula (1) as a thermal cationic polymerization initiator in an epoxy resin. This reduces the amount of fluorine ions generated during thermal cationic polymerization, improves the resistance to electrolytic corrosion, and realizes low-temperature rapid curability. Therefore, the present invention is preferably used when mounting an electronic component on a wiring board.

Claims (1)

1. An epoxy resin composition comprising an epoxy resin and a thermal cationic polymerization initiator, characterized in that the thermal cationic polymerization initiator is a sulfonium borate complex represented by the formula (1 a):

。

2an epoxy resin composition comprising an epoxy resin and a thermal cationic polymerization initiator, characterized in thatThe thermal cationic polymerization initiator is a sulfonium borate complex represented by formula (1 b):

。

3a method for producing an epoxy resin composition, wherein an epoxy resin composition is prepared by uniformly mixing and stirring an epoxy resin and a thermal cationic polymerization initiator, and a silane coupling agent, a thermosetting resin, and a filler added as needed, by a conventional method, and a sulfonium borate complex of formula (1) as the thermal cationic polymerization initiator is prepared as follows:

dissolving a sulfonium antimonate complex of formula (2) in an organic solvent, mixing an equimolar amount of an aqueous solution of a sodium borate salt of formula (3) into the solution, stirring the resulting 2-layer system mixture at a temperature of 20 to 80 ℃ for 1 to 3 hours, reacting the sulfonium antimonate complex of formula (2) with the sodium borate salt of formula (3) to obtain a sulfonium borate complex of formula (1),

in the above formula, R₁Is o-methylbenzyl or (1-naphthyl) methyl, n is 1, OH is bonded in para position, R₂Is methyl and X is fluorine atom.

4The method for producing an epoxy resin composition according to claim 3, wherein the organic solvent is ethyl acetate.