JP2817474B2 - Epoxy resin composition and cured product - Google Patents

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 particularly suitable for encapsulating semiconductor devices and a cured product thereof.

[0002]

2. Description of the Related Art Conventionally, as a package of a semiconductor device, good electric characteristics,
Epoxy resin compositions that provide cured products having mechanical properties, chemical resistance, moisture resistance, and the like are widely used. Above all,
A resin composition in which a phenol resin is blended with a novolak type epoxy resin as a curing agent and an inorganic filler is added to the resin composition is currently the mainstream of resin sealing of semiconductor devices.

However, in recent years, as chip sizes have become larger and more sophisticated, the requirements for sealing materials have become stricter, and sealing materials having both high thermal conductivity and low stress properties have been demanded.

Conventionally, crystalline silica has often been used as an inorganic filler to impart high thermal conductivity. However, epoxy resin compositions using crystalline silica have a large thermal expansion coefficient, and impart low stress properties. It is difficult to do.

On the other hand, when alumina is used as an inorganic filler, an epoxy resin composition satisfying both high thermal conductivity and low stress can be obtained.

On the other hand, when an organic phosphorus compound is used as a curing accelerator, it is known that an epoxy resin composition having excellent curability, storage stability, heat resistance, electrical properties, moisture resistance and the like can be obtained.

[0007] However, according to the study of the present inventors,
When alumina is used as the inorganic filler and the most common triphenylphosphine is used as the organic phosphorus compound-based curing accelerator, the obtained epoxy resin composition has excellent heat conductivity and low stress, but has excellent curing properties. It has been found that there is a problem that the fluctuation is large, and the curability is remarkably reduced particularly when the composition absorbs moisture, and the storage stability is poor.

[0008] Conventionally, the present applicant has previously described Japanese Patent Publication No.
No. 25010, In an epoxy resin composition containing an epoxy resin, a phenol resin as a curing agent, a curing accelerator, and an inorganic filler, the content of an organic acid as an epoxy resin is 100 ppm or less, and the content of chlorine ions is reduced. Amount is 2 ppm or less, and the content of hydrolyzable chlorine is 50 ppm.
A cresol novolak epoxy resin having an epoxy equivalent of 180 to 230 and a softening point of 80 to 120 ° C. and an organic acid content of 10
A novolak type phenol resin containing 0 ppm or less, free Na or Cl of 2 ppm or less, and free phenol of 1% or less is used. The epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the phenol resin are used. And the molar ratio (a / b) to the range of 0.8 to 1.5, and at least a functional group selected from a carboxyl group, a methylol group, an alkoxy group, and a hydroxyl group as a curing accelerator in the molecule. A tertiary organic phosphine compound having one compound, specifically a compound represented by the following formula (I), is added to the epoxy resin and the phenol resin in a total amount of 10%.
An epoxy resin composition characterized by using 0.4 to 5 parts by weight per 0 parts by weight has been proposed.

[0009]

Embedded image (Wherein, R ^{1 to} R ⁵ are each constituted by any of a hydrogen atom, a carboxyl group, a methylol group, an alkoxy group, and a hydroxyl group, and at least one of R ^{1 to} R ⁵
The individual is selected from a carboxyl group, a methylol group, an alkoxy group, and a hydroxyl group, and n is an integer of 1 to 3. )

The epoxy resin composition has curing properties,
Electrical properties at high temperature, heat resistance (high glass transition temperature Tg),
It has excellent moisture resistance properties, and as a result, it does not corrode and break even when left for a long time under high temperature and high humidity, and has excellent molding workability and long-term storage stability. .

[0011] However, the present inventor has disclosed Japanese Patent Publication No. 63-2
As a result of further study on the epoxy resin composition proposed in Japanese Patent No. 5010, the I.I.
When left in high temperature and high humidity with voltage applied to C,
The inventors have found that there is a problem that the aluminum wiring is often disconnected, and therefore, it has been desired to solve this problem.

The present invention has been made in view of the above circumstances,
It has excellent storage stability, cures quickly during heat molding, has excellent thermal conductivity and low stress, and gives a cured product with good thermal, electrical, mechanical, and chemical properties. It is an object of the present invention to provide an epoxy resin composition which is excellent in moisture resistance in a state where a voltage is applied and is useful for sealing a semiconductor and the like, and a cured product thereof.

[0013]

The present inventors have conducted intensive studies to achieve the above object, and as a result, the following general formula (4) was added to an epoxy resin composition containing an epoxy resin and a phenolic curing agent. It has been found that it is effective to mix alumina surface-treated with a specific silane coupling agent represented by the formula (1) and an organic phosphorus compound represented by the following general formula (1) as a curing accelerator.

[0014]

Embedded image (In the formula, X represents a hydrogen atom or a methoxy group.) R ⁴ _4-c Si (OR ⁵ ) _c (4) (where R ⁴ is a hydrogen atom, an alkyl group, an alkenyl group, or an aryl group) , An epoxy function, an amino function, an acrylic function or a carboxy function, R ⁵ represents an alkyl group, an alkenyl group or an aryl group, and c is 1-4.
It is. That is, by using an organic phosphorus compound having a specific structure represented by the above formula (1) with respect to alumina surface-treated with the silane coupling agent of the above formula (4),
Unlike the case of using triphenylphosphine etc. for untreated alumina, there is no decrease in curability even after moisture absorption, and it shows sufficient catalytic action only at the heating temperature during molding,
Therefore, during the heating and mixing of the epoxy resin and the curing agent and other components, and during subsequent storage, the curing does not proceed, and the storage stability is excellent. Was found to give a cured product having significantly increased moisture resistance. Therefore, the epoxy resin composition using the alumina surface-treated with the silane coupling agent of the formula (4) and the organic phosphorus compound represented by the formula (1) is subjected to the surface treatment with the silane coupling agent of the formula (4). The advantages of both alumina and organophosphorus compounds are effectively exerted, and are excellent in high thermal conductivity and low stress, and provide a cured product with good thermal, electrical, mechanical and chemical properties. I encapsulated with such an epoxy resin composition
It has been found that, even when exposed to high temperature and high humidity in a state where a voltage is applied to C, a remarkable effect is produced in that aluminum wires are hardly disconnected.

[0015] In this case, the following formula alkenyl groups the alkenyl group-containing epoxy resin or alkenyl group-containing phenol resin ^{_{(2) H a R 1 b}} SiO 2- (a + b) / 2 ... (2) ( where Wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and a and b represent 0.01 ≦ a ≦ 1, 1 ≦ b ≦ 3,
It is a positive number satisfying ≦ a + b <4. The number of silicon atoms in one molecule is an integer of 20 to 400, and the number of hydrogen atoms directly connected to the silicon atom in one molecule is an integer of 1 or more. By mixing a silicone-modified epoxy resin or a silicone-modified phenol resin, which is a polymer to which an SiH group of an organosilicon compound represented by the formula (1) is added, while exhibiting the above-described effects, it is excellent in low stress property. It has been found that the present invention can be made, and the present invention has been accomplished.

Accordingly, the present invention provides (1) an epoxy resin, (2) a phenolic curing agent, (3) a curing accelerator represented by the above formula (1), and (4) 0.001 to 100 parts by weight of alumina. An epoxy resin composition comprising 8 parts by weight of alumina surface-treated with a silane coupling agent represented by the above formula (4) as an essential component, and in particular, the composition further comprises a silicone-modified silicone resin. Provided is an epoxy resin composition containing an epoxy resin or a silicone-modified phenol resin, and a cured product thereof.

Hereinafter, the present invention will be described in more detail. The epoxy resin of the first essential component used in the epoxy resin composition of the present invention has one or more, especially two or more epoxy groups in one molecule. If there is no particular limitation,
For example, bisphenol type epoxy resin, alicyclic epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, triphenolmethane type epoxy resin, naphthalene ring-containing epoxy resin, aralkyl group-containing epoxy resin, etc. The species can be used alone or in combination of two or more.

The epoxy resin used in the present invention includes:
The organic acid content contained therein is 100 ppm or less, more preferably 20 ppm or less, chloride ion is 2 ppm or less, more preferably 1 ppm or less, and the content of hydrolyzable chlorine is 500 ppm or less, more preferably 300 pp.
m or less is preferably used. If at least one of these conditions is not satisfied, the moisture resistance may deteriorate.

The structure of the second essential component phenolic curing agent (phenolic resin) is not particularly limited as long as it has two or more phenolic hydroxyl groups in one molecule. For example, phenol novolak resin, cresol Novolak resins, naphthol resins, aralkylphenol resins, triphenol resins and the like are preferably used. Like the epoxy resin, it is preferable that the free Na and Cl in the phenol resin be 2 ppm or less from the viewpoint of the moisture resistance of the semiconductor. In addition, the phenol of the monomer contained therein,
That is, if the amount of free phenol exceeds 1%, in addition to adversely affecting the above-mentioned moisture resistance, when a molded article is formed from this composition, defects such as voids, unfilled parts, sink marks and the like are easily generated in the molded article. The amount of the free phenol is preferably 1% or less. Further, it is effective that the amount of organic acid such as formic acid generated by a Cannizzaro reaction of a trace amount of formaldehyde remaining during the production of the phenol resin is also 100 ppm or less from the viewpoint of the moisture resistance of the semiconductor.

The phenol resin has a softening point of 8
When the temperature is lower than 0 ° C., the glass transition temperature (Tg) decreases,
For this reason, the heat resistance may be deteriorated, and the softening point may be 1
If the temperature exceeds 20 ° C., the melt viscosity of the epoxy resin composition may increase and the workability may be poor, and in any case, the moisture resistance may be deteriorated. Therefore, the softening point of the phenol resin is set to 80 to 120 ° C. Is preferred.

The more preferable range of the amount of free phenol in the phenol resin is 0.3% or less, the more preferable range of the amount of the organic acid is 30 ppm or less, and the more preferable range of the softening point of the phenol resin is 90 to 110. ° C, and the object of the present invention can be more reliably achieved by adjusting the temperature within these ranges.

Further, the composition of the present invention preferably contains a silicone-modified phenolic resin and / or a silicone-modified epoxy resin, whereby the moisture resistance under a voltage applied state is more remarkably increased, and low linear expansion is achieved. And a composition giving a cured product having a low modulus of elasticity.

This silicone-modified phenol resin or silicone-modified epoxy resin is obtained by adding an SiH group of an organosilicon compound represented by the following general formula (2) to an alkenyl group of an alkenyl group-containing epoxy resin or an alkenyl group-containing phenol resin. Polymer.

[0024] ^{_{H a R 1 b SiO 2- (}} a + b) / 2 ... (2)

[0025]

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In this case, as the alkenyl group-containing epoxy resin or alkenyl group-containing phenol resin, an alkenyl group-containing epoxy resin or phenol resin represented by the following formula (3) is more preferably used. The addition polymer with the organic silicon compound represented by (2) is effective.

[0027]

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In this case, the silicone-modified epoxy resin or phenol resin described above has a hydrolyzable chlorine content of 500 ppm or less, free Na and Cl ions of 2 ppm or less, and an organic acid content of 100 ppm or less. Preferably, hydrolysable chlorine, free Na, Cl
If the content of ions or organic acids exceeds the above values, the heat resistance of the sealed semiconductor device may be deteriorated.

The above-mentioned silicone-modified epoxy resin or phenol resin may be used alone or as a mixture of two or more kinds. The compounding amount is 100 parts by weight of the total amount of the epoxy resin and the curing agent mixed in the composition ( It is preferably 5 to 70 parts, more preferably 8 to 50 parts per part by weight (hereinafter the same). If the blending amount of the silicone-modified epoxy resin or phenolic resin is less than 5 parts, it is difficult to obtain a sufficiently low stress property, and if it exceeds 70 parts, the mechanical strength of the molded article may decrease.

In the present invention, the epoxy resin (including the silicone-modified epoxy resin or phenol resin) and the phenol resin are used in a molar ratio between the epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the phenol resin. (A / b) is set to 0.8 to 1.5, preferably 0.1 to 1.5.
It is preferable to adjust to a range of 9 to 1.5. When the molar ratio of the two groups is less than 0.8, the curing properties of the composition and the glass transition temperature (Tg) of the molded article are deteriorated, and the heat resistance is reduced. And electrical characteristics may deteriorate.

Next, the composition of the present invention is used as a curing accelerator in the following general formula (1), more specifically (1a), (1)
The organic phosphorus compound shown in b) is used.

[0032]

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That is, a tertiary organic phosphine compound having a methoxy group introduced at the 2- and 6-positions of triphenylphosphine or a tertiary organic phosphine compound having a methoxy group introduced at the 4-position in addition to the 2- and 6-positions Other compounds, such as triphenylphosphine in which a methoxy group is not introduced or triphenylphosphine in which a methoxy group is introduced only at the 4-position, achieve the object of the present invention. Can not.

Further, in the present invention, the compound of the formula (1) may be used alone as a curing accelerator, but may be used in combination with another curing accelerator. Use in combination with 1,8-diazabicyclo-7-undecene is desirable from the viewpoint of the moisture resistance of the composition.

The compounding amount of the compound of the formula (1) is 0.1 to 10 with respect to 100 parts of the total amount of the epoxy resin as the first component and the phenolic curing agent (phenolic resin) as the second component. Parts, particularly 0.3 to 5 parts, is preferred. If the amount is less than 0.1 part, the curability may be poor. On the other hand, if it exceeds 10 parts, the storage stability and moisture resistance may be poor. . In addition, 1,8-diazabicyclo-7-
When undecene is used in combination, it is preferable to use 1,8-diazabicyclo-7-undecene in a proportion of 0.02 to 2 parts with respect to 1 part of the compound represented by the formula (1).

Next, in the present invention, alumina surface-treated with a specific silane coupling agent is blended as an inorganic filler for imparting low expansion and high thermal conductivity. The shape of alumina is not particularly limited, but is preferably spherical or nearly spherical. Its average particle size is preferably between 5 and 75 microns, but is less than 3% of the total inorganic filler material.
Those having an average particle diameter of 0.1 to 5 microns within a range not exceeding 0% may be used.

As alumina, the content of impurities such as sodium and chlorine is 10 ppm or less, particularly 5 pp.
m or less is preferable. If necessary, other inorganic fillers such as aluminum nitride may be used in combination with alumina. However, even in this case, the content of alumina in all the inorganic fillers may be set to 30% by weight or more, and the content of the inorganic filler may be reduced to 30% by weight or more. It is necessary to achieve the object of the invention.

Further, the amount of the inorganic filler contained in the composition is not particularly limited, but is preferably 60% by weight or more of the whole composition.

As the silane coupling agent for treating the alumina, the following general formula (4): R ⁴ _4-c Si (OR ⁵ ) _c (4) (where R ⁴ is a hydrogen atom, an alkyl group, R ⁵ represents an alkenyl group, an aryl group, an epoxy function, an amino function, an acrylic function or a carboxy function, R ⁵ represents an alkyl group, an alkenyl group or an aryl group, and c represents 1-4.
It is. )) Are used.

In the above formula, R ⁴ represents a hydrogen atom, a non-functional alkyl group such as a methyl group, an ethyl group, a propyl group or a phenyl group, an alkenyl group, an aryl group, and further an epoxy, amino, acrylic or carboxy functional group. Some examples are given below.

[0041]

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On the other hand, examples of R ⁵ include an alkyl group, an alkenyl group, and an aryl group. Among them, a methyl group, an ethyl group, an isopropenyl group and the like are common, and c is 1 to 4. However, it is preferable that c is 3 or 4.

As a method of treating alumina with a silane coupling agent, either a dry method or a wet method may be used.
The dry method can be performed by using a ball mill, a Henschel mixer, or the like, and the wet method can be performed by mixing and stirring a silane coupling agent with alumina in a solvent. The amount of the silane coupling agent is in the range of 0.001 to 8 parts, more preferably 0.01 to 5 parts, per 100 parts of alumina. If the amount of the silane coupling agent is too small, the effect of the treatment, that is, the improvement of the moisture resistance, etc., does not appear, and if the amount is too large, the burr characteristics may be rather deteriorated.
Two or more of these silane coupling agents may be used in combination, and those obtained by partially hydrolyzing these in advance may be used. Examples of the solvent used in the wet method include hydrocarbons such as toluene and xylene, alcohols such as methanol, ethanol and isopropyl alcohol, ketones such as acetone and 2-butanone, and ethers such as isopropyl ether and tetrahydrofuran. , Tin and titanium as water and hydrolysis promoter,
Alternatively, an amine compound can be used in combination. After the treatment in this manner, sintering can be performed in a heating furnace at about 400 to 1200 ° C.

The composition of the present invention may further contain various additives, if necessary, depending on the purpose and use. For example, waxes, release agents such as fatty acids such as stearic acid and metal salts thereof, pigments such as carbon black, dyes, flame retardants, surface treatment agents (such as γ-glycidoxypropyltrimethoxysilane), aging Inhibitors and other additives may be blended.

The composition of the present invention is prepared by uniformly stirring and mixing the required amounts of the above-mentioned components, kneading with a roll or kneader heated to 60 to 95 ° C. in advance, cooling, and pulverizing. Can be obtained at There is no particular limitation on the order of compounding the components.

The epoxy resin composition of the present invention comprises an IC, L
It is suitably used for sealing semiconductor devices such as SIs, transistors, thyristors, and diodes, and for manufacturing printed circuit boards. When the semiconductor device is sealed, a conventional molding method such as transfer molding, injection molding, and casting method can be employed. In this case, the molding temperature of the epoxy resin composition is 150 to 180 ° C., and the post cure is 150 to 1
It is preferable to carry out at 80 ° C. for 2 to 16 hours.

[0047]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In addition, in the following examples, a part shows a weight part.

Examples 1-4, Comparative Examples 1-4 Silicone modification which is an addition reaction product of an alkenyl group-containing epoxy resin represented by the following formula (5) and an organic silicon compound represented by the following formula (6) 50 parts of epoxy resin, 13 parts of cresol novolak type epoxy resin (epoxy equivalent 230),
5 parts of brominated epoxy resin (epoxy equivalent: 280), phenol novolak resin (phenol equivalent: 100) 32
Parts, 1.5 parts of carnauba wax, 1.5 parts of γ-glycidoxypropyltrimethoxysilane, 1.2 parts of carbon black, and an inorganic filler and a curing accelerator shown in Table 1 at 70-80 ° C. The mixture was kneaded with a roll, cooled and pulverized to obtain an epoxy resin composition.

[0049]

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The epoxy resin compositions were evaluated for hardness, glass transition temperature, coefficient of linear expansion, thermal conductivity, and corrosion rate of aluminum wiring (moisture resistance of power IC) by the following methods. The results are also shown in Table 1. Using a hardness transfer molding machine, 175 ℃ / 70kg ・ c
The hardness at hot after molding for 2 minutes at m ^-2 was measured using a Barcol hardness tester 9
35.

The measurement was made immediately after the preparation of the epoxy resin composition.
To the initial hardness, forcibly absorb moisture after preparation
The hardness of the composition having a water content of 0.15% by weight is absorbed.
The wet hardness was used.Linear expansion coefficient, glass transition temperature Using a 4mmφ × 15mm specimen, dilatometer
The temperature was measured at a rate of 5 ° C./min.Thermal conductivity 50mmφ × 6mm test piece with upper heater and calorimeter
Between the lower heater and the lower heater.
At a constant pressure and reach a steady state at 50 ° C.
The temperature difference between both sides of the test piece and the heat output
Calculate the conductance, test this thermal conductance value and test
The thermal conductivity was determined from the product of the thickness of the pieces. Aluminum corrosion test 14-pin IC with aluminum wiring on chip
Is molded with a transfer molding machine to form a molded product.
Post cure at 180 ° C for 4 hours.
In a test tank at 130 ° C. and 85% RH with pressure applied,
After leaving for 00 hours, disconnection of aluminum wiring is detected and
A good judgment was made (n = 20).

[0052]

[Table 1] * Alumina A: spherical alumina (average particle size 11 μm) 6
00 parts in a ball mill and 0.05% by weight of 1,8-
2.5 parts of γ-containing diazabicyclo-7-undecene
Glycidoxytripropylmethoxysilane was sprayed and dispersed uniformly. Thereafter, alumina subjected to heat treatment at 150 ° C. for 20 hours. ** Fused silica A: crushed fused silica having an average particle size of 11 μm. *** Crystalline silica A: Crystalline silica having an average particle size of 21 μm.

From the results shown in Table 1, when triphenylphosphine is used as a curing accelerator and used in combination with alumina (Comparative Example 1), the hardness at the time of moisture absorption is poor, the glass transition temperature is low, and the aluminum corrosion is poor. When an imidazole is used as a curing accelerator (Comparative Example 2), aluminum corrosion is extremely poor. When fused silica was used as the inorganic filler (Comparative Example 3), the coefficient of linear expansion was low, but the thermal conductivity was poor, and the aluminum corrosion was poor. Further, when crystalline silica was used as the inorganic filler (Comparative Example 4), the coefficient of linear expansion was large, and as a result, aluminum corrosion was poor.

On the other hand, the composition (Example) of the present invention using alumina as the inorganic filler and the organic phosphorus compound represented by the formula (1) as the curing accelerator together has a good hardness when absorbing moisture, High transition temperature, low coefficient of linear expansion, high thermal conductivity, excellent low stress,
It was confirmed that the aluminum corrosion resistance was excellent.

[0055]

As described above, the epoxy resin composition of the present invention has good storage stability, has both low stress properties and high thermal conductivity, and has thermal, electrical and mechanical properties. It provides a cured product having good chemical properties and excellent moisture resistance particularly in a state where a voltage is applied, and is useful for sealing semiconductor devices and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/31 (C08K 9/06 3:22 5:54) (72) Inventor Ryo Shinbi 1-chome Showacho, Kariya, Aichi Prefecture No. 1 Japan Denso Co., Ltd. (72) Inventor Yasutaka Yoshida 1-1-1 Showa-cho, Kariya City, Aichi Prefecture Japan Denso Co., Ltd. (56) References JP-A-3-20326 (JP, A) JP-A-2- 16118 (JP, A) JP-A-62-212417 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 63/00-63/10 C08K 9/06 C08K 3/22 C08G 59/62 C08G 59/40 H01L 23/29

Claims (3)

(57) [Claims] (1) an epoxy resin; (2) a phenolic curing agent; (3) a curing accelerator represented by the following general formula (1): (Wherein, X represents a hydrogen atom or a methoxy group.) (4) The surface was treated with 0.001 to 8 parts by weight of a silane coupling agent represented by the following general formula (4) per 100 parts by weight of alumina. Alumina R ⁴ _4-c Si (OR ⁵ ) _c (4) (where R ⁴ is a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an epoxy functional group, an amino functional group, an acrylic functional group, or a carboxy functional group) R ⁵ represents an alkyl group, an alkenyl group or an aryl group, and c represents 1 to 4
It is. An epoxy resin composition characterized by comprising (1) as an essential component. Wherein the alkenyl group-containing epoxy resin or alkenyl group-containing phenol resin represented by the following general formula alkenyl groups _{^{(2) H a R 1 b}} SiO 2- (a + b) / 2 ... (2) ( provided that wherein ^{R 1} Represents a substituted or unsubstituted monovalent hydrocarbon group, and a and b represent 0.01 ≦ a ≦ 1, 1 ≦ b ≦ 3,
It is a positive number satisfying ≦ a + b <4. The number of silicon atoms in one molecule is an integer of 20 to 400, and the number of hydrogen atoms directly connected to the silicon atom in one molecule is an integer of 1 or more. The epoxy resin composition according to claim 1, further comprising a silicone-modified epoxy resin or a silicone-modified phenol resin, which is a polymer obtained by adding a SiH group of the organosilicon compound represented by the formula (1). 3. A cured product obtained by curing the epoxy resin composition according to claim 1.