JPH06100665A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the compsn. having a low viscosity and giving a cured article excellent in heat resistance by compounding an epoxy resin with a novolac phenol resin contg. a low concn. of binuclear compds. and a high concn. of trinuclear compds. as a curative. CONSTITUTION:An epoxy resin is compounded with a novolac phenol resin which contains binuclear compds. in a concn. of 10wt.% or lower, tetranuclear compds. in a concn. of 5-15wt.%, and trinuclear compds. in a concn. 2-19 times that of the tetranuclear compds.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an epoxy resin composition. Specifically, the present invention relates to an epoxy resin composition containing a novolac type phenol resin.

[0002]

2. Description of the Related Art Generally, epoxy resins are excellent in adhesiveness, chemical resistance, electric characteristics and heat resistance, and are therefore widely used in adhesives, paints, electric materials and various composite materials.

Recent advances in semiconductor device-related technology are extremely fast and diversified. For example, the chip size becomes larger as the LSI becomes more highly integrated, while the package shape tends to become smaller and thinner. A so-called resin sealing method using an epoxy resin or the like is widely used as a method of sealing a semiconductor element. As the encapsulating resin, novolac type phenolic resin has become the mainstream of the encapsulating resin because of its heat resistance, moldability, electrical characteristics, and low cost of raw materials as a curing agent for epoxy resin or as a base resin for epoxy resin. ing. As a performance required for an epoxy resin which is a semiconductor sealing resin, a resin having a smaller amount and higher performance has been required.

For example, in the soldering process, the package itself is suddenly exposed to a high temperature of 200 ° C. or more, so that moisture and volatile components in the package are suddenly generated, and cracks are generated in the package, resulting in semiconductor reliability. Is a cause of lowering the heat resistance, and improving the heat resistance of the sealing resin is a major issue.

Further, the semiconductor element may be cracked by the stress caused by the difference in the coefficient of thermal expansion between the metal and the sealing material. In extreme cases, the chip itself may crack,
It's a problem. Therefore, a filler such as a filler is added in order to make the thermal expansion coefficient of the resin as close as possible to the metal used therein, but the addition amount is limited because the fluidity deteriorates. In order to increase the amount of filler, it is necessary that the resin has a lower viscosity. Therefore, in order to reduce the number of cracks and improve the heat resistance of the cured product, it is important to lower the viscosity of the resin itself.

In order to improve heat resistance, which is one of the required performances of epoxy resins for semiconductor encapsulation, attention was paid to the novolak type phenol resin as a curing agent, and particularly to the distribution of the cores of the novolac type phenol resin. When a novolac-type phenol resin having a low content of binuclear or less phenols that do not contribute to the crosslinking reaction, that is, free phenols and binuclear phenols, is used, the degree of crosslinking of the cured product is increased and the heat resistance temperature is improved. Further, since the volatile content is reduced, the workability is improved, and the number of cracks generated due to the volatile content is reduced. In addition, a filler such as a filler is often added as a means for improving heat resistance. Here too, it becomes necessary to lower the viscosity of the sealing resin so that the amount of the filler can be increased. That is, it is important to reduce the content of the components of the binuclear and lower components and to reduce the viscosity of the resin.

For example, Japanese Patent Laid-Open No. 2-70721 discloses a binuclear component in a range of 1.0% by weight to 5.0% by weight, a softening point of 80 ° C. to 120 ° C. and a number average molecular weight. There is disclosed an epoxy resin composition containing a novolac type phenol resin having a ratio of 300 to 900 as a curing agent. Since this resin has reduced the binuclear body, the degree of crosslinking increases. However, the viscosity was so high that the amount of filler for decreasing the linear expansion coefficient of the resin could not be increased.

Further, in Japanese Patent Application Laid-Open No. 3-24115, 2
Disclosed is an epoxy resin composition containing a novolac-type phenol resin containing 20% by weight or more of a nuclide and 35% by weight or more of a sum of a dinuclear component and a trinuclear component as a curing agent for an epoxy resin. Since the curing agent has a low molecular weight, it has a low viscosity, and it is possible to increase the amount of the filler such as an inorganic filler and to reduce the difference in the coefficient of thermal expansion. However, the heat resistance of the cured product was not improved due to the high content of the binuclear component, and the occurrence rate of cracks was not reduced due to the high volatile content.

Japanese Unexamined Patent Publication (Kokai) No. 4-68020 discloses an epoxy resin composition in which a liquid epoxy resin is used as the epoxy resin and a novolac type phenol resin is contained as a curing agent. By using a liquid epoxy resin, it is possible to reduce the viscosity without using a low molecular weight resin containing a large amount of volatiles as a curing agent, increase the amount of filler such as inorganic filler, and reduce the difference in thermal expansion coefficient. Became possible. However, the heat resistance and crack resistance of the cured product were insufficient.

Reducing the viscosity while maintaining the heat resistance of the cured product is very important for improving workability and performance not only for resin for semiconductor encapsulation but also for laminates, paints and various other applications.
This is one of the major challenges.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy resin composition having a low viscosity and a cured product having excellent heat resistance.

[0012]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made extensive studies to achieve the above object, and the novolac type phenolic resin to be contained has a low binuclear content in the resin and a trinuclear content. It has been found that the purpose can be achieved by using a resin having a high value, and finally the present invention has been completed.

That is, according to the present invention, in an epoxy resin composition containing an epoxy resin and a novolac type phenol resin as essential components, the novolac type phenol resin has a binuclear content of 10% by weight or less. ,
An epoxy resin composition comprising a novolac-type phenol resin having a tetranuclear body content of 5 to 15% by weight and a trinuclear body content of 2 to 19 times the tetranuclear body content. .

The epoxy resin which is an essential component of the present invention is 1
It is an epoxy resin containing two or more epoxy groups in the molecule. Phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, phenol aralkyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, flame-retardant brominated bisphenol A type epoxy resin, brominated bisphenol F type An epoxy resin etc. can be illustrated. Further, these epoxy resins may be liquid epoxy resins. The viscosity can be further reduced by using a liquid epoxy resin. Although these epoxy resins may be used alone, 2
It may be a mixture of two or more species.

The most characteristic feature of the novolak type phenolic resin contained in the epoxy resin composition of the present invention is that it has a low nuclide content and a high trinuclear content distribution in the resin. Is. The novolac type phenolic resin having such a characteristic nuclide distribution has a low binuclear content that does not contribute to the crosslinking reaction, so that the cured product has a high degree of crosslinking and the heat resistance is improved. Further, when the content of the binuclear body is lowered, the viscosity is increased as compared with the case where the binuclear body is contained, but in the present invention, the content of the trinuclear body is high, so that the glass transition point (hereinafter Tg Can have a low melt viscosity that cannot be obtained with the same novolac type phenolic resin.

The content of binuclear bodies in the novolak type phenolic resin which is an essential component of the present invention is usually 10% by weight or less. Since the binuclear body does not contribute to the crosslinking reaction, its content is preferably low. However, as the content of the binuclear body increases, the viscosity decreases, so that the binuclear body can be contained within a range that does not hinder the required degree of crosslinking.

The tetranuclear content in the novolac type phenol resin is in the range of 5 to 15% by weight. The trinuclear content in the novolac type phenolic resin is 2 with respect to the tetranuclear content.
~ 19 times.

A resin having a nuclear distribution satisfying these conditions can realize a novolac type phenol resin having a low melt viscosity as compared with a resin which gives a cured product having the same glass transition temperature (Tg).

The epoxy resin composition of the present invention is a novolac type phenolic resin and an epoxy resin composition containing an epoxy resin as an essential component, but other phenolic resins, curing accelerators, various additives, etc. may be added to the epoxy resin composition of the present invention. You may add in the range which does not spoil the purpose.

In the epoxy resin composition of the present invention, a compound which accelerates the reaction between the epoxy group of the epoxy resin and the hydroxyl group of the curing agent can be used. Examples of the curing accelerator include nitrogen-containing compounds, phosphines and onium salts.

The mixing ratio of the epoxy resin and the novolac type phenol resin is generally such that the hydroxyl group of the curing agent resin is 0.1 to 10 with respect to 1 mol of the epoxy group of the epoxy resin.

An example of the production of the novolac type phenol resin of the present invention will be described. First, the phenols are 4 to 30 mole times the formaldehyde (hereinafter P / F = 4 to 3).
Mix with the ratio of about 0) and add an acidic catalyst to 60
A condensation reaction is performed at -100 ° C for 4 hours to produce an initial condensate. Then, the obtained initial condensate is heated under atmospheric pressure to remove water and a small amount of phenols, and further heated under reduced pressure to remove unreacted phenols. Next, a novolac-type phenol resin having a low content of dinuclear bodies and a high content of trinuclear bodies is obtained as bottom product by distillation under reduced pressure with a device equipped with a packing material such as McMahon packing, while further raising the temperature. You can The binuclear body content can be controlled by the temperature and pressure during distillation. The removal of the binuclear body may be carried out by vacuum distillation as described above, but it may also be carried out by extraction or steam distillation. The content ratio of the trinuclear or higher component can be controlled by the reaction molar ratio. The resin having a high trinuclear body content obtained as the bottom product may be used as it is as a resin composition, but a formaldehyde source such as formalin is added to the bottom product as a raw material for further condensation reaction, The resin of any molecular weight, ie 2
It is also possible to obtain a novolak-type phenol resin having a low content of nucleolar and a high content of trinuclear.

Further, the distilled binuclear body can be utilized as useful bisphenol Fs.

Examples of the phenols as a raw material of the novolac type phenol resin of the present invention include cresol, ortho or para, and meta-substituted alkylphenols in addition to phenol.

Examples of formaldehyde sources include formalin, paraformaldehyde, hexamethylenetetramine, trioxane and cyclic formal.

The reaction molar ratio for obtaining the novolac type phenol resin of the present invention is P / F = 4 or more, preferably 8 or more. The resin having a higher trinuclear content is obtained as the reaction molar ratio is higher.

Examples of the acidic catalyst used in the reaction of the formaldehyde source and the phenols in the present invention include organic acids such as hydrochloric acid, sulfuric acid, paratoluenesulfonic acid and oxalic acid, and inorganic acids.

In the present invention, when the novolac type phenol resin is produced by adding a formaldehyde source to the novolac type phenol resin to produce a higher molecular weight, the amount of formaldehyde added is the average molecular weight of the resin to which formaldehyde is added or the distribution of the nucleus. by. For example, when trying to obtain a resin having a number average molecular weight of about 600, 11 to 12% by weight based on the resin produced at a reaction molar ratio P / F = 10.
It is sufficient to add about 37% formalin aqueous solution.

[0029]

The present invention will be described in more detail with reference to Examples and Comparative Examples. The evaluation or measurement of various characteristic values in the examples was carried out by the following methods (1) to (4).

(1) Content of Each Nucleus The content of each nucleus expressed in% in the specification is determined by gel permeation chromatography (column: Tosoh G4000HX).
L + G2500HXL + G2000HXL × 2, eluent: tetrahydrofuran, detector: differential refractometer).

(2) Viscosity The viscosity was measured at 130 ° C. using an ICI cone & plate type viscometer (manufactured by Research Equipment Co., London).

(3) Glass transition temperature (Tg) Tg was measured by the TMA (thermo-mechanical analysis) method.

(4) Softening point The softening point was measured according to JIS K-2207 (ring and ball method).

1. Production of Novolac Phenolic Resin Example 1 Phenol 2000 g and 37% formalin aqueous solution 17
2.5 g was mixed (P / F = 10), 5.6 g of oxalic acid dihydrate was added, and the reaction was carried out at 70 ° C. for 4 hours.

The reaction product mixture is then brought to atmospheric pressure at 1
The mixture was heated to 60 ° C to remove water and a small amount of phenol, and further heated to 170 ° C at a final 20 mmHg to separate unreacted phenol. After that, 6mmH
g, heated to 210 ° C. to remove phenol. Next, distillation was performed by an apparatus equipped with a McMahon packing having a diameter of 15 mm and a height of 20 mm to 3 mmHg and a final temperature of 250 ° C. to obtain a bottom product. 40g of this canned product and 37%
2.0 g of a formalin aqueous solution was mixed, 0.11 g of oxalic acid dihydrate was added, and the reaction was carried out at 100 ° C. for 2 hours. Then, the obtained reaction product is heated to 100 to 100 at atmospheric pressure.
Dehydrated by heating to 150 ℃, 280mmHg, 17
Water was removed by heating to 0 ° C. The target phenolic resin was obtained by the above operation. When the obtained resin was cooled to room temperature, a pulverizable solid substance was obtained. [Table 1] shows the binuclear content, trinuclear content, tetranuclear content, viscosity and softening point of the obtained resin.

Example 2 As in Example 1, 2000 g of phenol and 172.5 g of 37% formalin aqueous solution were mixed (P / F = 10),
5.6 g of oxalic acid dihydrate was added and the reaction was carried out at 70 ° C. for 4 hours. Then, using the same apparatus as in Example 1, dephenoling was carried out, and distillation was carried out at a final pressure of 3 mmHg and a final temperature of 24.
The temperature was raised to 5 ° C. to obtain a bottom product. This canned product 40g and 37
% Formalin aqueous solution (3.2 g) was mixed, 0.11 g of oxalic acid dihydrate was added, and the reaction was carried out at 100 ° C. for 2 hours. Then, the obtained reaction product is heated to 100 to 100 at atmospheric pressure.
Dehydrated by heating to 150 ℃, 280mmHg, 17
Water was removed by heating to 0 ° C. The target novolak type phenolic resin was obtained by the above operation. The binuclear content, trinuclear content, tetranuclear content, viscosity and softening point of the obtained resin are shown in [Table 1].

Comparative Example 1 Phenol 2000 g and 37% formalin aqueous solution 104
Example 1 except mixing with 0 g (P / F = 1.66)
The reaction was carried out under the same conditions as. Then, using the same apparatus as in Example 1, the distillation was performed at a final pressure of 3 mmHg and a final temperature of 220 ° C.
Until I got a canned product. When the bottom product was cooled to room temperature, a non-crushable paste resin was obtained. The content of binuclear bodies, the content of trinuclear bodies, the content of tetranuclear bodies, the viscosity,
The softening points are shown in [Table 1].

Comparative Example 2 Phenol 2000 g and 37% formalin aqueous solution 115
Example 1 except mixing with 0 g (P / F = 1.51)
The reaction was carried out under the same conditions as. Next, using the same apparatus as in Example 1, the distillation was performed at a final pressure of 3 mmHg and a final temperature of 250 ° C.
Until I got a canned product. When the bottom product was cooled to room temperature, a resin was obtained as a pulverizable solid. 2 in resin
[Table 1] shows the nuclear content, trinuclear content, tetranuclear content, viscosity and softening point.

2. Production of Epoxy Cured Product For each of the obtained resins, this output, an epoxy equivalent of 214, and an orthocresol novolac type epoxy resin having a softening point of 75 ° C. (manufactured by Nippon Kayaku Co., Ltd., trade name: EOC)
N102S, viscosity (150 ° C) 6.3P), triphenylphosphine (hereinafter abbreviated as TPP) as a curing accelerator, montanic acid glycol ester wax as a release agent, carbon black as a colorant, and silica as a filler, Roll kneading was performed under conditions of a kneading temperature of 100 to 110 ° C. and a kneading time of 5 minutes. The sheet-shaped kneaded product was cooled and then pulverized to obtain an epoxy resin composition.

Next, the composition is compression-molded for 5 minutes to prepare a molded article having a predetermined shape, and further, 175 ° C.
I did post cure for 5 hours. The Tg of the obtained molded product is shown in [Table 1].

The compounding ratio of each composition is as follows: 49 parts by weight of novolac type phenol resin as a curing agent, 1.2 parts by weight of TPP, 2 parts by weight of montanic acid glycol ester wax, relative to 100 parts by weight of the epoxy resin as the main component. The ratio is 1 part by weight of carbon black and 450 parts by weight of silica.

[0042]

[Table 1] The unit of each nuclear content is area%. The unit of viscosity is P
(Measured at 130 ° C.). The unit of Tg is ° C. The unit of softening point is ° C.

[0043]

INDUSTRIAL APPLICABILITY According to the present invention, the novolak-type phenol resin contained as an epoxy resin composition has a nucleus distribution of 10% or less for a dinuclear or less component and a tetranuclear content of 5 to 15%. The trinuclear body content rate is 2 to the tetranuclear body content rate.
By using a 19-fold phenol resin, a resin having a lower melt viscosity than a resin having the same Tg, which represents the heat resistance of a cured product, is realized.

For example, when the Tg of Example 1 is 148 ° C. and the Tg of Comparative Example 1 is 148 ° C., the viscosity is 4.5.
It is P and 7.3P, and it can be said that the viscosity of the phenol resin of the present invention is low. The same can be said from Example 2 and Comparative Example 2.

Claims (1)

[Claims] 1. An epoxy resin composition containing an epoxy resin and a novolac-type phenol resin as essential components, wherein the novolac-type phenol resin has a binuclear content in the resin of 10% by weight or less, and 4 An epoxy resin composition comprising a novolac-type phenol resin having a nucleolar content of 5 to 15% by weight and a trinuclear content of 2 to 19 times the tetranuclear content.