JP2000072848A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for semiconductors having good storage stability, excellent in curing property as well as fluidity and moisture resistance by including an epoxy resin, a phenol resin and a specific phosphorane. SOLUTION: This resin composition basically contains three components of (A) an epoxy resin (e.g. bisphenol A type epoxy resin), (B) a phenol resin (e.g. phenol novolak resin) and (C) an organic phosphorane of the formula (R1 to R3 are each an alkyl, an aralkyl or the like; R4 and R5 are each an electron attracting group or an organic group). The component A is preferably compounded with the component B so that hydroxy group in the component B becomes 0.5-2.0 per epoxy equivalent in the component A. The component C is preferably compounded in an amount of 0.1-20 pts.wt. based on 100 total amount of the components A and B, with the components A and B. Additives such as an inorganic filler, a silane coupling agent, a mold release agent and a flame retardant can be added to the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having good storage stability, excellent curability, excellent fluidity and moisture resistance.

[0002]

2. Description of the Related Art In general, a catalyst (curing accelerator) is added to an epoxy resin composition for semiconductor encapsulation in order to accelerate curing during molding. However, this catalyst has a problem of deteriorating the quality of the resin composition because it exhibits a curing acceleration effect even at a temperature as low as about room temperature. In other words, when used as a sealing material for semiconductor elements such as ICs and LSIs and electrical components, problems such as poor filling due to reduced fluidity during molding, breakage of gold wires of IC chips, and poor conduction are caused. I was holding it.

For example, when an imidazole compound, an amine, a nitrogen-containing heterocyclic compound, an organic phosphine compound, or the like is used as a catalyst, low-temperature storage during storage / transportation, management during mixing with various components, molding conditions It was not possible to avoid the troublesome work for quality control after production, such as the strictness of manufacturing.

Therefore, in order to improve the storage stability, in recent years, studies have been made on making the catalytic activity latent so that it does not show activity at a relatively low temperature of about room temperature but shows activity only at the time of heat molding. For example, there are techniques such as microencapsulation and chemical modification. The currently most effective approach among these approaches is the quaternary phosphonium conversion of tertiary phosphines. By using a borate salt or an organic acid salt of a tetra-substituted phosphonium as a catalyst, a resin composition having good storage stability, excellent fluidity, and excellent curability can be obtained by those skilled in the art. Is already known.

[0005] However, since the catalyst has a salt structure, when dispersed in a resin matrix, free anions adversely affect moisture resistance and may cause corrosion of IC chips. Therefore, development of a non-salt catalyst having no ionic structure has been demanded as a catalyst.

[0006]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in order to overcome the above problems.
An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation having good storage stability, excellent curability, excellent fluidity and moisture resistance.

[0007]

Means for Solving the Problems In order to achieve the above object, the present inventors have studied the control of the catalytic activity of an organic phosphorane by a substituent. It has been found that the introduction of a sex substituent allows both excellent storage stability and curability to be achieved, and the present inventors have further studied and completed the present invention.

That is, the present invention is characterized in that it basically contains three components of an epoxy resin (A), a phenol resin (B), and an organic phosphorane (C) represented by the following general formula (1). It is a resin composition.

[0009]

Embedded image In the formula, the substituents R ^{1 to} R ³ are an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, which may be the same or different. R ⁴ and R ⁵ are an electron-withdrawing group or an organic group, at least one of which is an electron-withdrawing group, and one or both of R ⁴ and R ⁵ contain 6 or more carbon atoms. Thus, they may be the same or different from each other.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin (A) used in the present invention is not particularly limited as long as it has two or more epoxy groups in a molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, brominated epoxy resin, biphenyl type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, cycloaliphatic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin Trifunctional epoxy resins, for example, trishydroxynphenylmethane type epoxy resin, triglycidyl isocyanate resin, stilbene type epoxy resin, and phenol resin synthesized by a condensation reaction of dicyclopentadiene and phenols And epoxy resins obtained by glycidyl etherification, such as naphthalene type epoxy resins, various epoxy resins conventionally used for sealing of semiconductor device is used. In addition, since it is only necessary to have two or more epoxy groups in the molecule, it may be generally interpreted as a monomer, catechol or resorcin epoxidized with epichlorohydrin, polycyclic hydrocarbon And epoxidized dihydroxynaphthalene.

The phenolic resin (B) used together with the above epoxy resin acts as a curing agent for the epoxy resin, and is a resin obtained by a condensation reaction between phenols and formaldehyde. Here, the phenols are defined as those in which a hydrogen atom on an aromatic ring of a molecule having aromaticity such as benzene, naphthalene, and ferrocene is substituted with a hydroxyl group. The obtained resin includes so-called phenol novolak resin, cresol novolak resin, t-butylphenol novolak resin, naphthol resin, and nonylphenol novolak resin, as well as resol type resins. In addition to the resins obtained by the condensation reaction between these phenols and formaldehyde, those obtained by reacting paraxylene dimethanol with phenol, such as phenol aralkyl resins, and phenol obtained by the reaction of dicyclopentadiene and phenols as described above Resins are also included in the category of phenolic resins in the present invention.

The mixing ratio B / A of the epoxy resin and the phenolic resin in the present invention is preferably such that the hydroxyl group in the phenolic resin is 0.5 to 2.0 per equivalent of the epoxy group in the epoxy resin. . If the ratio is out of the above range, sufficient curability may not be obtained.

An organic phosphorane (C) is used as a catalyst (curing accelerator) in addition to the epoxy resin and the phenol resin, and its structure is represented by the following general formula (1).

[0014]

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In the formula, the substituents R ^{1 to} R ³ are an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, for example, a methyl group, an ethyl group, a butyl group, an allyl group, a phenyl group. Examples thereof include a group, a tolyl group, an ethylphenyl group, an alkoxyphenyl group, a benzyl group and a naphthyl group, which may be the same or different.

R ⁴ and R ⁵ are an electron-withdrawing group or an organic group, at least one of which is an electron-withdrawing group, and one or both of R ⁴ and R ⁵ have 6 or more carbon atoms. And they may be the same or different from each other. As a combination of R ⁴ and R ⁵ , when one is an organic group containing 6 or more carbon atoms and the other is an electron withdrawing group, one is an organic group containing 6 or more carbon atoms and the other is an organic group containing 6 or more carbon atoms. When the number of the electron-withdrawing groups is 6 or more, one is an electron-withdrawing group containing 6 or more carbon atoms, and when the other is an organic group, one is an electron-withdrawing group containing 6 or more carbon atoms. When the other is an electron withdrawing group, one is an electron withdrawing group containing 6 or more carbon atoms, and the other is an electron withdrawing group containing 6 or more carbon atoms. Examples of each combination are shown in equations (2) to (6).

[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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Examples of the organic group having 6 or more carbon atoms include an amyl group, a normal hexyl group, a phenyl group, a tolyl group,
An ethylphenyl group, an alkoxyphenyl group and the like are suitable in terms of handling and supply of raw materials. When these bulky substituents were introduced, an improvement in storage stability was observed. This is presumably because the reactivity of the catalytically active site (Zwitter ion site) of the organic phosphorane is sterically shielded. However, the curability tends to decrease with respect to the improvement of storage stability due to the three-dimensional effect. Therefore, an electron withdrawing group was introduced for the purpose of improving curability.

Examples of the electron withdrawing group include a cyano group, a nitro group, a halogen, a trifluoroacetyl group, an acyl group, a formyl group, a carboxyl group and an ester group. If Hammett's concept is adopted as the definition of the electron-withdrawing group, those having a positive value of σP-X can be called an electron-withdrawing group (Tokyo Kagaku Doujin “Organic Reaction Mechanism”, 5th edition, P3
77-381).

Considering the electronic effect of the substituent, it is possible to predict the catalytic activity from spectroscopic data obtained by NMR (nuclear magnetic resonance) or IR (infrared absorption) measurement. For example, a chemical shift value of an absorption signal in 31P-NMR can be used. The chemical shift of triphenylphosphoranylidene acetate, which has the same catalytic activity as that of triphenylphosphine, is observed at 14.7 ppm. Activity is expected. This is because it is considered that the 31P-NMR observation value reflects the electron density on the phosphorus atom.

The amount of the organic phosphorane (C) is based on 100 parts by weight of the total of the epoxy resin and the phenol resin.
Preferably, it is used in the range of 0.1 to 20 parts by weight. That is, if the amount of the organic phosphorane is less than 0.1 part by weight, a sufficient curing promoting effect cannot be obtained, and if it exceeds 20 parts by weight, the fluidity and moisture resistance during molding may be reduced. .

The epoxy resin composition according to the present invention may further comprise, if necessary, an inorganic filler,
Silane coupling agents, release agents, flame retardants, pigments, etc.
Additives known to those skilled in the art can be added.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. First, a molding material was prepared, and a spiral flow, a curing torque, and a flow residual ratio after storage of the molding material were measured for property evaluation. Further, a pressure cooker test (PCT) was performed on the molded part.
Each evaluation method was as follows.

1. Spiral flow Using a mold for spiral flow measurement according to EMMI-I-66, mold temperature 175 ° C, injection pressure 70kg / c
Measured in m ² , curing time 2 minutes. Spiral flow (cm)
Is a parameter of fluidity, and a larger value indicates greater fluidity.

2. Curing torque Using a curast meter (manufactured by Orientec Co., Ltd., JSR curast meter IVPS type) at 175 ° C., 90
Find the torque after second heating. Torque in a curast meter is a parameter of curability, and a larger value indicates higher curability.

3. Spiral flow immediately after molding material preparation, and 3
The spiral flow after storage at 0 ° C. for 7 days was measured, and the spiral flow (cm) immediately after the material preparation was determined.
The percentage of spiral flow (cm) after storage was calculated.
The larger the value of the residual flow rate, the better the storage stability.

4. Pressure Cooker Test (PCT) A 16pDIP equipped with a test element was molded at 175 ° C. for 2 minutes, and then post-cured at 175 ° C. for 8 hours. A moisture resistance test was performed. The defect judgment is 5 when n = 10.
The time when the individual conduction failure occurred was defined as a 50% failure occurrence time. The longer the 50% failure occurrence time, the better the moisture resistance.

(Example 1) Orthocresol novolak type epoxy resin having a softening point of 65 ° C and an epoxy equivalent of 210 (EOCN-1025-65, manufactured by Nippon Kayaku Co., Ltd.)
Phenol novolak resin having a softening point of 105 ° C. and a hydroxyl equivalent of 104 by weight (PR-514, manufactured by Sumitomo Durez Co., Ltd.)
70) were mixed with 2.0 parts by weight of an organic phosphorane represented by the formula (2) as a catalyst, 300 parts by weight of fused silica, and 2 parts by weight of carnauba wax.
For 8 minutes to obtain a molding material. This molding material has a spiral flow of 95 cm and a curing torque of 79 kgf.
Cm. The residual flow rate is 98%, and P
In the CT humidity resistance test, no failure occurred up to 2000 hours.

(Example 2) Epoxy resin having a structure represented by the formula (7) (YX4000 manufactured by Yuka Shell Epoxy Co., Ltd.)
H, epoxy equivalents 187 to 197), 52 parts by weight, 48 parts by weight of a phenol resin having a structure represented by the formula (8), 3.0 parts by weight of an organic phosphorane represented by the formula (2) as a catalyst, spherical fused silica 800 parts by weight and 3 parts by weight of carnauba wax were blended, and a molding material was prepared in the same manner as in Example 1. The spiral flow of the obtained molding material was 88 cm, and the curing torque was 82 kgf · cm.
The flow residual rate was 95%, and no failure occurred in the PCT humidity resistance test until 2000 hours.

[0034]

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[0035]

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(Embodiments 3, 5, 7 and 9) Embodiment 1
, A molding material was prepared by repeating the same blending and operation as in Example 1 except that the catalyst was changed to 2.0 parts by weight of the organic phosphoranes represented by Formulas (3) to (6). The evaluation results of the obtained molding materials were as shown in Table 1.

(Examples 4, 6, 8, and 10) The procedure of Example 2 was repeated except that the catalyst was replaced by 3.0 parts by weight of the organic phosphorane represented by the formulas (3) to (6). The same blending and operation as in Example 2 were repeated to prepare a molding material. The evaluation results of the obtained molding materials were as shown in Table 1.

Comparative Example 1 A molding material was prepared in the same manner as in Example 1, except that the catalyst was changed to 0.8 parts by weight of triphenylphosphine. The spiral flow of the obtained molding material is 76 cm,
The curing torque was 61 kgf · cm. The flow residual rate was 43%, and the 50% failure occurrence time in the PCT humidity resistance test was 1,300 hours.

Comparative Example 2 A molding material was prepared by repeating the same blending and operation as in Example 2, except that the catalyst was changed to 1.2 parts by weight of triphenylphosphine. The spiral flow of the obtained molding material is 92 cm,
The curing torque was 66 kgf · cm. The flow residual rate was 51%, and the 50% failure occurrence time in the PCT humidity resistance test was 1,400 hours.

Comparative Examples 3 and 5 In Example 1, 2.5 parts by weight of tetraphenylphosphonium tetraphenylborate (TPP-K) and 2.0 parts by weight of an organic phosphorane represented by the formula (9) were used. A molding material was prepared by repeating the same blending and operation as in Example 1 except that the parts were changed. The evaluation results of the obtained molding materials were as shown in Table 1.

(Comparative Examples 4 and 6) The procedure of Example 2 was repeated, except that the catalyst was replaced by 4.0 parts by weight of TPP-K and 3.0 parts by weight of the organic phosphorane represented by the formula (9), respectively. By repeating the same blending and operation as in Example 2, a molding material was prepared. The evaluation results of the obtained molding materials were as shown in Table 1.

[0042]

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[0043]

[Table 1]

The resin compositions of Examples 1 to 10 containing the organophosphorane catalyst of the present invention had good fluidity immediately after production and exhibited extremely high flow residual ratio. It can be seen that they have excellent storage stability. In addition, the curing torque also showed a high value, and the PCT 50% failure occurrence time was at a level exceeding 2000 hours, which clearly indicates that the composition has excellent curability and moisture resistance.

On the other hand, in Comparative Examples 1 and 2, although the fluidity and the curability show the same good values as in the example, the flow residual ratio shows a low value of 50% or less, and the storage stability is low. There's a problem. In Comparative Examples 3 and 4, although the fluidity, curability, and storage stability were good, the PCT 50% failure occurrence time was 1000 hours or less, and the moisture resistance was poor.
Comparative Examples 5 and 6 are excellent in the PCT 50% failure occurrence time, but are insufficient in storage stability.

[0046]

The epoxy resin composition according to the present invention has improved storage stability and curability by utilizing, as a catalyst, an organic phosphorane having a sterically bulky substituent and an electron-withdrawing substituent. Both of them are excellent in so-called latent curability and hardly cause a curing reaction at about room temperature, so that stable storage for a long period of time has become possible. In addition, since the catalyst has a non-salt structure, it provides a material having excellent moisture resistance, and thus is particularly useful as a semiconductor sealing material.

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Claims (3)

[Claims] 1. A resin composition comprising basically three components of an epoxy resin (A), a phenol resin (B), and an organic phosphorane (C) represented by the following general formula (1). object. Embedded image In the formula, the substituents R ^{1 to} R ³ are an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, which may be the same or different. R ⁴ and R ⁵ are an electron-withdrawing group or an organic group, at least one of which is an electron-withdrawing group, and one or both of R ⁴ and R ⁵ contain 6 or more carbon atoms. Thus, they may be the same or different from each other. 2. One of the substituents R ⁴ and R ⁵ of the organophosphorane represented by the general formula (1) is a straight-chain alkyl group or an aryl group having 6 or more carbon atoms,
The resin composition according to claim 1. 3. The electron-withdrawing group is one or two types of substituents selected from the group consisting of a cyano group, a nitro group, a halogen, a trifluoroacetyl group, an acyl group, a formyl group, a carboxyl group, and an ester group. The resin composition according to claim 1, wherein