Epoxy resin composition

Abstract

Provided is an epoxy resin composition that uses a curing accelerator that is an excellent curing accelerator for reactions between epoxy resins and curing agents and that does not produce free chlorine. The present invention is an epoxy resin composition comprising: a phosphonium salt (S) represented by general formula (1) and composed of a phosphonium cation (A) and an n-valent carboxylate anion (B); an epoxy resin (C); and a curing agent (D). [In formula (1), R1 to R3 are each independently a C6-12 aryl group; R4 is a C1-6 alkyl group; n represents an integer from 1-6; and Xn- represents an n-valent carboxylate anion.]

Description

[Technical field]

[0001] The present invention relates to an epoxy resin composition. More specifically, the present invention relates to an epoxy resin composition suitable for producing an epoxy resin-based sealant for electronic parts, such as a semiconductor sealing material. [Background technology]

[0002] Epoxy resins have been used in electronic materials such as semiconductor encapsulation materials due to their excellent adhesiveness, insulating properties, and heat resistance. However, in recent years, epoxy resins are also desired to have a low dielectric tangent in order to suppress energy loss in high-frequency communications, for example, high-frequency communications of 1 GHz or higher. In order to meet the need for a low dielectric tangent, a method has been disclosed in which epoxy resin and active ester resin are used as a curing agent (for example, Patent Document 1). In this way, a low dielectric tangent can be achieved because the reaction is between epoxy resin and active ester resin, and in principle, no hydroxyl groups are generated.

[0003] However, the reaction between active ester resin and epoxy resin is very slow, and the development of a more effective curing accelerator is urgently needed. The curing accelerator generally considered to be the most effective is 4-dimethylaminopyridine, but this compound has a very strong nucleophilicity, so while it works as a curing accelerator, it also nucleophiles epoxy resins, which causes the chlorine covalently bonded to epoxy resins to be released, generating free chlorine in the resin. This free chlorine is problematic in that it deteriorates the reliability of devices for electronic components.

[0004] On the other hand, in the field of power electronics, a low dielectric tangent is desired to suppress energy loss at a relatively low frequency, for example, 100 kHz. The need for a low dielectric tangent at this frequency is required at high temperatures, for example, 155°C, so it is effective to increase the crosslink density of the resin and raise the glass transition temperature after curing. However, when using a multifunctional epoxy resin to increase the crosslink density, there is no suitable curing accelerator, and there is a drawback that free chlorine is generated in the same way as when using 4-dimethylaminopyridine, which has high nucleophilicity. In addition, triphenylphosphine, which has low nucleophilicity, is insufficient as a curing accelerator and has poor curing properties, resulting in a lower glass transition temperature, and the purpose was not achieved. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-252957 A Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide an epoxy resin composition using a curing accelerator which is excellent as a curing accelerator in the reaction between an epoxy resin and a curing agent and which does not generate free chlorine. [Means for solving the problem]

[0007] As a result of investigations aimed at achieving the above object, the present inventors arrived at the present invention. That is, the present invention is an epoxy resin composition containing a phosphonium salt (S) composed of a phosphonium cation (A) represented by the general formula (1) and an n-valent carboxylate anion (B), an epoxy resin (C), and a curing agent (D).

[0008] [ka]

[0009] [In formula (1), R1 to R3 each independently represent an aryl group having 6 to 12 carbon atoms, R4 represents an alkyl group having 1 to 6 carbon atoms, n represents an integer of 1 to 6, and X n- represents an n-valent carboxylate anion. Effect of the Invention

[0010] In the epoxy resin composition of the present invention, the phosphonium salt (S) acts as a curing accelerator. The phosphonium cation (A), which is the cationic component of the phosphonium salt (S), is represented by the formula (1), where R1 to R3 are each independently an aryl group having 6 to 12 carbon atoms, and R4 is an alkyl group having 1 to 6 carbon atoms. Since it is a conjugated structure of three aryl groups, it is stable, and since there is one alkyl group, even if it decomposes when exposed to high temperatures, it does not generate harmful substances such as benzene. The anionic component is an n-valent carboxylate anion (B), where n represents an integer of 1 to 6. In other words, the absence of free carboxylic acid increases the reactivity as a curing accelerator.

[0011] In addition, the phosphonium salt (S) of the present invention has a relatively low melting point because the phosphonium cation (A) has a conjugated structure of three aryl groups and the n-valent carboxylate anion (B) has no free carboxylic acid, and by incorporating the salt even at the compounding temperature at which it is heated and melted, it is easy to knead while suppressing the promotion of the curing reaction. Therefore, it can be kneaded uniformly and can function as a curing accelerator. Furthermore, at the curing temperature at which the temperature is raised, it quickly dissociates and can promote the reaction between the epoxy resin and the curing agent, so the reactivity of the epoxy resin composition can be increased and free chlorine can be suppressed. In other words, it can increase the reliability of semiconductor devices and is suitable for producing epoxy resin-based sealing materials for electronic components such as semiconductors. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The epoxy resin composition of the present invention will be described below. The epoxy resin curing accelerator of the epoxy resin composition of the present invention is a phosphonium salt (S). It consists of a phosphonium cation (A) represented by the general formula (1) and an n-valent carboxylate anion (B).

[0013] The melting point of the phosphonium salt (S) is preferably 160° C. or lower, and more preferably 130° C. or lower. From the viewpoint of ease of handling, the lower limit is preferably −50° C. or higher. The melting point is more preferably −30° C. to 120° C., even more preferably −20° C. to 120° C., and most preferably 50° C. to 120° C.

[0014] In the phosphonium cation (A), in the general formula (1), R1 to R3 are each independently an aryl group having 6 to 12 carbon atoms, and R4 is an alkyl group having 1 to 6 carbon atoms. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a methylphenyl group, and a methylnaphthyl group. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an isopropyl group, and a butyl group.

[0015] Specific examples of the phosphonium cation (A) include a triphenylmethylphosphonium cation, a triphenylethylphosphonium cation, a triphenylbutylphosphonium cation, a tri(p-tolyl)ethylphosphonium cation, a trinaphthylmethylphosphonium cation, and a trinaphthylethylphosphonium cation.

[0016] The phosphonium cation (A) can be produced, for example, by reacting a tertiary phosphonium with an alkylating agent. Examples of the alkylating agent include alkyl halides and alkyl carbonates.

[0017] Examples of the n-valent carboxylate anion (B) include an octylate anion, an adipate anion, a sebacate anion, an orthophthalate anion, an isophthalate anion (m-phthalate anion), a paraphthalate anion, a benzoate anion, a succinate anion, a maleate anion, a salicylate anion, a pyrrolimetic anion, and a trimesylate anion. The n-valent represents the number of carboxylic acids, and n represents an integer of 1 to 6. Among these, aromatic carboxylate anions are preferred from the viewpoint of reliability. Also, from the viewpoint of reactivity, polyfunctional carboxylate anions in which n is 2 or more are preferred, and n is even more preferably 2 to 4.

[0018] Epoxy resin (C) refers to those having epoxy groups in the molecule, and is generally an oligomer or polymer, and its molecular weight and molecular structure are not particularly limited. Also, epoxy resins having two or more epoxy groups in one molecule are preferred, such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, hydroquinone type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, stilbene type epoxy resins, triphenol methane type epoxy resins, alkyl-modified triphenol methane type epoxy resins, triazine nucleus-containing epoxy resins, dicyclopentadiene-modified phenol type epoxy resins, phenol aralkyl type epoxy resins having phenylene and / or biphenylene skeletons, naphthol type epoxy resins, naphthalene type epoxy resins, naphthol aralkyl type epoxy resins having phenylene and / or biphenylene skeletons, etc., which may be used alone or in combination.

[0019] Examples of the epoxy resin (C) include HP-4032, HP-4700, HP-7200, HP-820, HP-4770, HP-5000, EXA-850, EXA-830, EXA-1514, and EXA-4850 series manufactured by DIC Corporation; EPPN-201L, BREN-105, EPPN-502H, EOCN-1020, NC-2000-L, XD-1000, NC-7000L, NC-7300L, EPPN-501H, and NC-3000 manufactured by Nippon Kayaku Co., Ltd.; and XY-4000 manufactured by Mitsubishi Chemical Corporation.

[0020] The curing agent (D) includes an active ester resin (D1), a phenol resin (D2), an acid anhydride compound, and the like.

[0021] Examples of the active ester resin (D1) include aromatic esters obtained by condensation reaction of aromatic carboxylic acid selected from those in which two or more hydrogen atoms of the aromatic ring of benzene, naphthalene, biphenyl, diphenylpropane, diphenylmethane, diphenylether, diphenylsulfone, etc. are substituted with carboxyl groups, and phenols in which one hydrogen atom of the aromatic ring of benzene, naphthalene, biphenyl, diphenylpropane, diphenylmethane, diphenylether, diphenylsulfone, etc. is substituted with a hydroxyl group. Specific examples include the active ester resins described in MATERIAL STAGE Vol.18, No.6 2018, P71-78 (written by Koike Tsuneo).

[0022] The phenolic resin (D2) is preferably a compound having two or more phenolic hydroxyl groups in one molecule, and is generally an oligomer or polymer having two or more phenolic hydroxyl groups in one molecule. There are no particular limitations on the molecular weight or molecular structure of the phenolic resin. Examples of the phenolic resin (D2) include phenol novolac resin, cresol novolac resin, triphenolmethane type phenolic resin, terpene modified phenolic resin, dicyclopentadiene modified phenolic resin, phenol aralkyl resin having a phenylene and / or biphenylene skeleton, naphthol aralkyl resin having a phenylene and / or biphenylene skeleton, and bisphenol compounds, which may be used alone or in combination.

[0023] Examples of compounds having two or more phenolic hydroxyl groups include the HF series, H series, MEH-7500 series, MEH-7800 series, MEH-7851 series, MEH-7600 series, and MEH-8000 series manufactured by Meiwa Kasei Co., Ltd.; and TriP-PA, BisP-TMC, BisP-AP, OC-BP, TekP-4HBPA, and CyRS-PRD4 manufactured by Honshu Chemical Industry Co., Ltd.

[0024] Examples of the acid anhydride include the Rikacid series manufactured by New Japan Chemical Co., Ltd.

[0025] Among these curing agents (D), when emphasis is placed on energy loss in the high frequency region, active esters (D1) are preferred, and when emphasis is placed on energy loss at high temperatures in the low frequency region, phenolic resins (D2) are preferred.

[0026] The epoxy resin composition of the present invention preferably further contains a compound (E) represented by general formula (2), and the content of the compound (E) is more preferably 0.5 to 1.5 equivalents relative to the n-valent carboxylate anion (B).

[0027] [ka]

[0028] [In formula (2), R6, R7, and R8 represent a hydrogen atom or a hydroxyl group, and at least one of them is a hydroxyl group.]

[0029] In the general formula (2), R6, R7, and R8 each represent a hydrogen atom or a hydroxyl group, and at least one of them is a hydroxyl group. More preferably, R6 is a hydroxyl group.

[0030] The epoxy resin composition of the present invention is finally cured to obtain a cured epoxy resin (cured product) by curing the composition. The amounts of the phosphonium salt (S), epoxy resin (C) and curing agent (D) are adjusted according to the reactivity of the epoxy resin and curing agent, and the amount of the phosphonium salt (S) is usually 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, per 100 parts by weight of the epoxy resin (C).

[0031] The compounding ratio of the epoxy resin (C) and the curing agent (D) is not particularly limited, but it is preferable to use the curing agent (D) so that the ratio of the acid anhydride equivalent or the hydroxyl group equivalent to 1 equivalent of the epoxy group of the epoxy resin (C) is 0.5 to 2 equivalents, and more preferably 0.7 to 1.5 equivalents.

[0032] The epoxy resin composition of the present invention preferably further contains an inorganic filler (H). When the epoxy resin composition of the present invention is used for sealing electronic components such as semiconductor elements, a compound is blended into the epoxy resin composition for the purpose of improving the solder resistance of the resulting semiconductor device, and the like. There are no particular limitations on the type of compound, and any compound generally used as a sealing material can be used.

[0033] The content of the inorganic filler (H) is not particularly limited, but is preferably 200 to 2400 parts by weight, more preferably 400 to 1400 parts by weight, per 100 parts by weight of the total amount of the epoxy resin (C) and the curing agent (D).

[0034] The epoxy resin composition of the present invention preferably further contains other functional compounds (functional additives).

[0035] Examples of functional additives include coupling agents such as alkoxysilanes, titanate esters, and aluminate esters, such as 3-glycidyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, and phenyltrimethoxysilane; colorants such as carbon black; flame retardants such as brominated epoxy resins, antimony oxide, aluminum hydroxide, magnesium hydroxide, zinc oxide, and phosphorus-based compounds; low-stress components such as silicone oil and silicone rubber; natural waxes such as carnauba wax, and synthetic waxes such as polyethylene wax; release agents such as higher fatty acids, metal salts of the higher fatty acids, and paraffin; various additives such as magnesium, aluminum, titanium, and bismuth-based ion catchers and bismuth antioxidants; and modified compounds that increase heat resistance, such as benzoxazine, cyanate esters, and bismaleimides.

[0036] Other functional compounds are described in "Review of Epoxy Resins, Vol. 1", "Review of Epoxy Resins, Vol. 1", Epoxy Resin Technology Association, 2003; Journal of Electronics Packaging Society, 14, 204, 2011; Journal of Applied Polymer Science, 109, 2023-2028, 2008; Polymer Preprints, Japan, 60, 1K19, 2011; Network Polymer, 33, 130, 2012; Polym. Int. 54, 1103-1109, 2005; Journal of Applied Polymer Science, 92, 2375-2386, 2004; Network Polymer, 29, 175, 2008; Polymer Journal, 65, 562, 2008; Polymer Journal, 66(6), 217, 2009, etc.

[0037] The epoxy resin composition of the present invention can be obtained by uniformly mixing the above-mentioned components and, if necessary, other additives, etc., using a mixer, and further by heating and kneading the mixture at room temperature using a kneading machine such as a roll, a kneader, a co-kneader, or a twin-screw extruder, followed by cooling and pulverization. When the epoxy resin composition obtained above is in the form of a powder, it can also be pressed into tablets using a press or the like for use in order to improve workability during use.

[0038] The epoxy resin composition of the present invention can be used, for example, for encapsulating various electronic components such as semiconductor elements to produce semiconductor devices, by curing and molding the composition according to a conventional molding method such as transfer molding, compression molding, and injection molding. EXAMPLES

[0039] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereto. In the following, % means % by weight, and parts means parts by weight, unless otherwise specified. The details of the epoxy resin curing accelerator (hereinafter referred to as the curing accelerator) which is a phosphonium (S) used in the examples and comparative examples are shown below.

[0040] <Method for producing phosphonium salt (S1)> 177 parts of diethyl carbonate and 500 parts of ethanol as a solvent were charged into a stirred autoclave, and 262 parts of triphenylphosphine were charged into it and reacted at a reaction temperature of 135°C for 80 hours to obtain an ethanol solution of triphenylethylphosphonium ethyl carbonate (S1-1). 83 parts of isophthalic acid were added to this and the solvent was removed using an evaporator to produce triphenylethylphosphonium isophthalate (S1). The structure is represented by the following formula (S1).

[0041] [ka]

[0042] <Method for producing phosphonium salt (S2)> By using 135 parts of dimethyl carbonate instead of diethyl carbonate in the manufacturing method of phosphonium salt (S1), triphenylmethylphosphonium isophthalate (S2) was obtained. The structure is represented by the following formula (S2).

[0043] [ka]

[0044] <Method for producing phosphonium salt (S3)> By using 122 parts of benzoic acid instead of isophthalic acid in the manufacturing method of phosphonium salt (S1), triphenylethyl phosphonium benzoate (S3) was obtained. The structure is represented by the following formula (S3).

[0045] [ka]

[0046] <Method for producing phosphonium salt (S4)> By using 73 parts of adipic acid instead of isophthalic acid in the manufacturing method of phosphonium salt (S2), triphenylmethylphosphonium adipate (S4) was obtained. The structure is represented by the following formula (S4).

[0047] [ka]

[0048] <Method for producing phosphonium salt (S5)> Instead of triphenylphosphine in the manufacturing method of the phosphonium salt (S1), 304 parts of tri(p-tolyl)phosphine was used to obtain tri(p-tolyl)ethylphosphonium isophthalate (S5). The structure is represented by the following formula (S5).

[0049] [ka]

[0050] <Method for producing phosphonium salt (S6)> By using 261 parts of dibutyl carbonate instead of diethyl carbonate in the manufacturing method of phosphonium salt (S1), triphenylbutylphosphonium isophthalate (S6) was obtained. The structure is represented by the following formula (S6).

[0051] [ka]

[0052] <Method for producing phosphonium salt (S7)> By using 63.5 parts of pyrrolimetic acid instead of isophthalic acid in the manufacturing method of phosphonium salt (S1), triphenylethylphosphonium pyrrolimetic acid salt (S7) was obtained. The structure is represented by the following formula (S7).

[0053] [ka]

[0054] <Method for producing phosphonium salt (S8)> By using 70 parts of trimesylic acid instead of isophthalic acid in the manufacturing method of phosphonium salt (S1), triphenylethylphosphonium trimesylate (S8) was obtained. The structure is represented by the following formula (S8).

[0055] [ka]

[0056] <Production Example of Salt (S'1) Used in Comparative Example>

[0057] <Method of producing salt (S'1)> 939 parts of an ethanol solution of triphenylethylphosphonium ethyl carbonate (S1-1), 240 parts of triethoxyphenylsilane, 320 parts of 2,3-dihydroxynaphthalene, and 30 parts of a 28% methanol solution of sodium methoxide were added to 900 parts of ethanol to obtain the phosphonium salt (S'1) represented by the following formula. The salt was purified by filtering, washing with methanol several times, and drying to obtain the salt (S'1). The structure is represented by the following formula (S'1).

[0058] [ka]

[0059] The melting points of the phosphonium salts (S1) to (S4) and the salt (S′1) were measured by the following method. The results are shown in Table 1. <Melting point> The sample was placed on a stainless steel test bench, and the temperature was gradually increased, and the temperature at which it melted was read visually.

[0060] [Table 1]

[0061] <Method for producing active ester compound (D1-1)> 33 parts of isophthalic acid, 58 parts of 1-naphthol, and 49 parts of acetic anhydride were placed in a round-bottomed, three-necked glass flask equipped with a dropping funnel and a reflux condenser, and reacted at 145°C for 5 hours in a nitrogen atmosphere to acetylate 1-naphthol. The reaction was then carried out at 200-250°C to carry out an esterification reaction of 1-naphthol while deacetylating it. The product obtained was thoroughly washed with methanol and dried under reduced pressure at 50°C to obtain an active ester compound (D1-1) of 1-naphthol and isophthalic acid.

[0062] Example 1 Epoxy resin (C-1): 100 parts of Nippon Kayaku Co., Ltd.'s product name NC3000 (softening point 58°C, epoxy equivalent 273); 65 parts of the active ester compound (D1-1) obtained in the above example as a curing agent (D); and 4 parts of the triphenylethylphosphonium isophthalate (S1) obtained in the above example as a curing accelerator were melt-kneaded for 10 minutes in an oil bath at 130°C, cooled, and pulverized to obtain epoxy resin composition 1. The obtained epoxy resin composition 1 was evaluated by the evaluation methods described below, and the results are shown in Table 2.

[0063] <Dielectric tangent measurement> The dielectric tangent of the cured material, which had been cured at 175°C for 5 hours, was measured using an LCR meter (Agilent Technologies, E4980A) at 30°C, 1 GHz or 155°C, 100 Hz. The lower the value, the less the energy loss.

[0064] <Glass transition temperature> The cured product cured at 175°C for 5 hours was measured by thermomechanical analysis (TMA) under conditions of 30 to 250°C and 10°C / min to determine the glass transition temperature.

[0065] <Measurement of free chlorine ions> 10 parts of the cured product cured at 175°C for 5 hours were heated together with 100 parts of ultrapure water in an autoclave at 160°C for 20 hours, and the chlorine content of the liquid was measured using an ion chromatograph.

[0066] Examples 2 to 8, Comparative Examples 1 to 3 As shown in Table 2, epoxy resin compositions 2 to 8 and comparative epoxy resin composition 1 were obtained in the same manner as in Example 1, while changing the phosphonium salt (S). In addition, in Comparative Examples 2 to 3, triphenylphosphine and 4-dimethylaminopyridine were used instead of the phosphonium salt (S), and comparative epoxy resin compositions 2 to 3 were obtained. Evaluations were performed in the same manner as in Example 1, and the results are shown in Table 2.

[0067] [Table 2]

[0068] Example 9 Epoxy resin (C-1): 100 parts of Nippon Kayaku Co., Ltd.'s product name NC3000 (softening point 58°C, epoxy equivalent 273); phenol resin (D2) as hardener (D): 33 parts of Meiwa Kasei Co., Ltd.'s product name MEH-7500 (softening point 110°C, hydroxyl equivalent 97); 3 parts of triphenylethylphosphonium isophthalate (S1) were melt-kneaded in a 110°C oil bath for 5 minutes, cooled, and pulverized to obtain epoxy resin composition 9. The obtained epoxy resin composition 5 was evaluated by the above-mentioned evaluation method and the results are shown in Table 3.

[0069] Examples 10 to 19, Comparative Examples 4 to 6 As shown in Table 3, epoxy resin compositions 10 to 19 and comparative epoxy resin composition 4 were obtained in the same manner as in Example 9, with the phosphonium salt (S) changed. Epoxy resin compositions 17, 18, and 19 were obtained in the same manner as in Example 9, except that 0.41 parts of catechol (E-1) was further added in Example 17, 0.53 parts of pyrogallol (E-2) was added in Example 18, and 0.48 parts of pyrogallol (E-2) was added in Example 19. In addition, in Comparative Examples 5 and 6, triphenylphosphine and 4-dimethylaminopyridine were used instead of the phosphonium salt (S), and comparative epoxy resin compositions 5 and 6 were obtained. Evaluation was performed in the same manner as in Example 9, and the results are shown in Table 3.

[0070] [Table 3]

[0071] As is clear from Tables 2 and 3, the epoxy resin compositions of Examples 1 to 19 of the present invention have lower dielectric tangents, higher glass transition temperatures, and lower free chlorine contents than the comparative examples. On the other hand, Comparative Examples 1 to 6 have poor results in at least one of the above items. [Industrial Applicability]

[0072] The epoxy resin composition of the present invention has good flowability and is an epoxy resin composition with improved reliability, and is suitable for producing an epoxy resin-based sealing material for electronic parts such as semiconductors.

Claims

1. An epoxy resin composition comprising a phosphonium salt (S) consisting of a phosphonium cation (A) represented by general formula (1) and a divalent to tetravalent carboxylate anion (B), an epoxy resin (C), and a curing agent (D), wherein the curing agent (D) is an active ester resin (D1). 【Chemistry 1】 [In formula (1), R1 to R3 each independently represent an aryl group having 6 to 12 carbon atoms, R4 represents an alkyl group having 1 to 6 carbon atoms, n represents an integer of 2 to 4, and X ｎ－ represents a divalent to tetravalent carboxylate anion.

2. 2. The epoxy resin composition according to claim 1, wherein the phosphonium salt (S) has a melting point of 160° C. or lower.

3. 3. The epoxy resin composition according to claim 1, comprising 0.5 to 1.5 equivalents of the compound (E) represented by the general formula (2) relative to the divalent to tetravalent carboxylate anion (B). 【Chemistry 2】 [In formula (2), R6, R7, and R8 represent a hydrogen atom or a hydroxyl group, and at least one of them is a hydroxyl group.]

4. A cured product obtained by curing the epoxy resin composition according to any one of claims 1 to 3.

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