JP2002088141A - Epoxy resin composition, prepreg and copper-clad laminate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition giving excellent flame retardance and excellent heat resistance and dimensional stability without using a halogen-based flame-retardant, a prepreg and a copper-clad laminate using the prepreg. SOLUTION: This flame-retardant resin composition is characterized by comprising (A) an epoxy resin containing three or more epoxy groups in one molecule, (B) a phenol resin-based curing agent containing three or more phenolic hydroxy groups in one molecule, (C) 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide and (D) a spherical fused silica which is previously subjected to a surface treatment with a coupling agent and has <=2 μm average particle diameter as essential components. This prepreg and this copper-clad laminate using the prepreg are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition, prepreg, which has excellent flame retardancy without using a halogen-based flame retardant, and exhibits excellent heat resistance and dimensional stability. It relates to the used copper-clad laminate.
In particular, the present invention relates to a copper-clad laminate suitable for use in a rigid interposer for an IC package.

[0002]

2. Description of the Related Art In the field of semiconductors, the trend of shifting from conventional surface mounting to area mounting has progressed due to the progress of high-density mounting technology, and new packages such as BGA and CSP have appeared and are increasing. For this reason, rigid substrates for interposers have attracted more attention than ever before, and demands for substrates having high heat resistance and low thermal expansion have increased. In general, in order to reduce the coefficient of thermal expansion of a substrate, it is widely used to use an inorganic filler, particularly fused silica,
In the case of conventionally used coarse-grained fused silica, there is a problem that moisture stays in a space formed by sandwiching a coarse filler in a narrow gap between a glass base material and a copper foil constituting a substrate and solder heat resistance is reduced. The present inventors have confirmed this. On the other hand, when fine-grained fused silica is used, the above problem is solved, but a problem of silica aggregation occurs. Even when such agglomeration occurs, problems such as poor appearance or moisture retention in the space formed by the agglomerates and reduction in solder heat resistance occur. In Japanese Patent Application Laid-Open No. 9-272155, 0.3 to 5 μm
However, there is no description of an optimum resin composition for an interposer substrate and no mention of the problem of aggregation. According to the present inventors, even if spherical silica is used, if agglomeration occurs, appearance defects will occur, or moisture will remain in the space where the agglomerates are formed, and solder heat resistance will be reduced. On the other hand, resin members used for these semiconductors are often required to have flame retardancy. Conventionally, in order to impart this flame retardancy, it has been common to use a halogen-based flame retardant such as a brominated epoxy in an epoxy resin. However, since dioxins may be generated from halogen-containing compounds, the use of halogen-based flame retardants has been avoided with the worsening of environmental problems in recent years. There is a growing need for a system for conversion. Phosphorus-based flame retardants have been spotlighted in response to the demands of such times, and phosphate esters and red phosphorus have been studied.However, these conventional phosphorus-based flame retardants are easily hydrolyzed and have a poor reaction with resin, so solder There are problems that heat resistance is lowered and glass transition temperature is lowered.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made to solve such a problem, and is a halogen-free solder having excellent flame retardancy, high heat resistance, low thermal expansion, and low water absorption. An object of the present invention is to provide an epoxy resin composition suitable for a rigid interposer having heat resistance, and a prepreg and a copper-clad laminate using the same.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a polyfunctional epoxy resin and a phenol resin-based curing agent which contribute to heat resistance,
A copper clad laminate for interposers containing a phosphorus compound of a specific structure having flame retardancy and excellent hydrolysis resistance, and a specific spherical silica that realizes low thermal expansion and low water absorption and does not cause aggregation as essential components The main technical gist is an epoxy resin composition suitable for the above, and the above-mentioned object has been achieved by such composition and process.

Specifically, (A) an epoxy resin having three or more epoxy groups in one molecule, and (B) three or more epoxy groups in one molecule.
A phenolic resin-based curing agent having at least two phenolic hydroxyl groups, (C) 9,10-dihydro-9-oxa-10
Average particle size 2 previously surface-treated with phosphaphenanthrene-10-oxide and (D) a coupling agent
μm or less spherical fused silica, and an epoxy resin composition characterized by being an essential component, a prepreg characterized by impregnating them into a fiber base material, and dried, and further, in obtaining a prepreg, A prepreg characterized in that spherical fused silica having a particle size of 2 μm or less is surface-treated by a specific process and used. And a copper-clad laminate formed by heat-molding using the prepreg.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin (A) having three or more epoxy groups in one molecule used in the present invention includes orthocresol novolak epoxy resin, phenol novolak epoxy resin, bisphenol A novolak epoxy resin and the like. Derivatives such as novolak type epoxy resin, trishydroxyphenylmethane type epoxy resin and corresponding epoxy resin in which aromatic ring is alkylated, glycidyl etherified product of 1,1,2,2-tetrakishydroxyphenylethane, and dimer thereof Tetrakishydroxyphenylethane-type epoxy resin such as dimer, trimer and the like. Epoxy resin is
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-, a reactive phosphorus compound described below.
Since the oxide reacts with the epoxy group to decrease the epoxy group in the resin, it is essential that the epoxy resin is a trifunctional or higher functional epoxy resin in order to keep the glass transition temperature high.

[0007] Particularly, among epoxy resins having three or more functional groups,
When a novolak type epoxy resin (A1) and at least one type of epoxy resin (A2) selected from a trishydroxyphenylmethane type epoxy resin and a tetrakishydroxyphenylethane type epoxy resin are combined,
Trishydroxyphenylmethane type epoxy resin or tetrakishydroxyphenylethane type epoxy resin (A
In 2), the glass transition temperature can be increased by increasing the crosslink density,
On the other hand, the novolak type epoxy resin (A1) can prevent the disadvantages of the epoxy resin (A2), such as brittleness due to excessively high water absorption and excessively high crosslinking density, and decrease in adhesion. In particular, among the novolak-type epoxy resins (A1), ortho-cresol novolak epoxy resin is preferable because the water absorption can be reduced.

In the present invention, the proportion of the component (A) in the epoxy resin composition is preferably from 10 to 50% by weight. If the content is less than 10% by weight, the amount of the binder component is reduced, and the heat resistance, particularly the solder crack resistance as an interposer of the IC package, is reduced. If it exceeds 50% by weight, the proportion of the filler decreases, the thermal expansion and the water absorption increase, and the solder cracking resistance as an interposer of the IC package decreases, which is not preferable. Here, the solder crack resistance as an interposer refers to a JGA performed in a BGA or a CSP using a rigid interposer.
In a solder cracking resistance test according to the EDEC mounting rank condition, it means a resistance to a crack or an interface peeling caused by an interposer or indirectly affected by characteristics of the interposer. In addition, as the epoxy resin, an epoxy resin other than the component (A), for example, a bisphenol A type epoxy resin may be blended in an amount of 30% by weight or less of the entire epoxy resin.

Next, examples of the phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule of the component (B) include phenol novolak, bisphenol A novolak, and phenol aralkyl resin. Phenol novolak, which has a relatively small hydroxyl equivalent and can easily remove low-functional monomers, is preferred. In the present invention, the component (B) is added so that the equivalent ratio of the epoxy group of the epoxy resin to the total of the phenolic hydroxyl group and other active hydrogen of the component (B) is 0.8 or more and 1.2 or less. Is preferred. Outside this range, a decrease in glass transition temperature and an increase in water absorption cause a decrease in solder cracking resistance as an interposer of an IC package,
In some cases, a decrease in the moisture resistance reliability may occur.

The flame retardant component of the present invention, component (C) 9,
10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is a reactive phosphorus compound in which hydrogen bonded to phosphorus reacts with an epoxy group, such as a conventional phosphoric acid ester or red phosphorus. It is an extremely excellent phosphorus-based flame retardant without hydrolyzing to increase water absorption or reducing adhesion. Component (C) of the present invention is added in an amount of 0.5 to 10 based on the entire epoxy resin composition.
% By weight is preferred. If it is less than 0.5% by weight, the flame-retardant effect may be reduced. If it exceeds 10% by weight, the glass transition temperature and the water absorption are increased, and especially the soldering heat resistance as an interposer of the IC package is reduced, and In some cases, the reliability of humidity resistance may be reduced.

The component (D) of the present invention is spherical fused silica having an average particle diameter of 2 μm or less which has been surface-treated with a coupling agent in advance. In order to achieve both low thermal expansion and resin fluidity by adding a large amount of filler, spherical fused silica is optimal because it is superior to other fillers. Fine spherical silica having an average particle size of 2 μm or less easily aggregates, and this aggregate may form a space at an interface between a resin, a glass cloth, a copper foil and the like and deteriorate solder heat resistance. Such a problem does not occur because silica has been previously surface-treated with a coupling agent.

The surface treatment method in the present invention is not particularly limited as long as it does not generate agglomerates. Conventionally, a wet method, that is, diluting a coupling agent in a solvent or the like and mixing a filler. A method, or a method of subsequent drying, and a dry method, that is, a method of spraying a coupling agent while stirring a filler with a mixer, and the like are performed. Among them, in the step of dissolving the epoxy resin composition in a solvent to form a varnish, applying it to a fiber base material and drying to obtain a prepreg, at the time of preparing the varnish, as spherical fused silica surface-treated with a coupling agent, Particle size 2μm
When the following spherical fused silica, a coupling agent, and a solvent are mixed and a slurry is prepared by heat reaction, the surface treatment of the spherical fused silica is extremely effectively performed.

The coupling agent in spherical fused silica having an average particle diameter of 2 μm or less which has been surface-treated in advance with a coupling agent is a silane coupling agent or a silicone having two or more repeating units of siloxane bonds and having an alkoxy group. Examples include a silicon-based coupling agent such as an oil-type coupling agent and a titanate-based coupling agent.
From the viewpoint of improving the wettability of the surfaces of the epoxy resin and the fused spherical silica, silicon-based coupling agents are preferred. Specifically, a silicone oil-type cup having at least two repeating units of an epoxy silane coupling agent, an amino silane coupling agent, a ureido silane coupling agent, a mercapto silane coupling agent, a disilazane, and a siloxane bond, and having an alkoxy group. At least one member selected from the group consisting of ring agents is exemplified. Especially when an epoxy silane coupling agent, an amino silane coupling agent and a silicone oil type coupling agent having two or more repeating units of siloxane bond and having an alkoxy group are used in combination, the coupling agent is efficiently attached to the silica surface. Establish. In these cases, the ratio of the coupling agent is generally 0.1 part or more and 10 parts or less with respect to 100 parts of spherical fused silica (hereinafter, all "parts" represent parts by weight).

When the above-mentioned spherical fused silica, coupling agent and solvent are mixed and reacted by heating to form a slurry, the heating temperature is preferably between 50 ° C. and 120 ° C. When a heating reaction is performed at a temperature in this range, the reaction between the silanol on the silica surface and the coupling agent selectively occurs. If the temperature is lower than this range, the reaction becomes slow. If the temperature is higher than this range, a coupling reaction between the coupling agents and volatilization occur, which is not preferable.
The mixing ratio of the spherical fused silica, the coupling agent, and the solvent can be arbitrarily set, but the coupling agent is usually 0.1 to 10 parts and the solvent is 10 to 200 parts by weight based on 100 parts of the spherical fused silica. Part or less. Outside this range, the efficiency of the surface treatment may decrease. The slurry after the surface treatment is completed may be re-dispersed in a different solvent before being filtered and dried, or the solvent may be reduced by decantation as required. However, when using this method,
In order to prevent reaggregation, it is preferable that the surface-treated spherical fused silica slurry is mixed with other components without drying.

In any method, when a coupling agent is used for the surface treatment, water or an acid, if necessary, is used to promote the reaction between the coupling agent and the silanol of silica.
Use of an alkali or the like is included in the present invention. When the spherical fused silica having an average particle size of 2 μm or less accounts for 50% by weight or more of the epoxy resin composition, thermal expansion and water absorption are reduced, which is preferable. However, when the content exceeds 90% by weight, the proportion of the inorganic filler in the epoxy resin composition is too large, and operations such as impregnation become difficult. If necessary, other fillers may be used as long as the properties are not hindered. In this case, conventionally known fillers including spherical silica other than spherical fused silica having an average particle diameter of 2 μm or less which has been previously surface-treated with the coupling agent of the present invention, to the extent that properties such as solder heat resistance are not deteriorated, Can be used arbitrarily.

The epoxy resin composition of the present invention can optionally contain additives other than the above components as long as the properties are not impaired. The epoxy resin composition of the present invention can be applied to a substrate as a varnish using a solvent or without a solvent to obtain a prepreg. As the substrate, a glass woven fabric, a glass nonwoven fabric, or another organic substrate can be used. A prepreg is obtained by impregnating and drying a fiber base material with the epoxy resin composition of the present invention, and one or more of the prepregs are heat-formed together with a copper foil to obtain a copper-clad laminate. These prepregs and copper-clad laminates are also included in the present invention.

[0017]

Example 1 60 parts of spherical fused silica having an average particle diameter of 0.5 μm was charged into a Henschel mixer, and while stirring, 0.5 parts of γ-glycidoxypropyltrimethoxysilane and a silicone oil type coupling agent A ( Nippon Unicar MAC2101)
0.1 part was added little by little. After completion of the addition, the mixture was stirred for 5 minutes and taken out. Orthocresol novolak epoxy resin (Epiclon N-665 manufactured by Dainippon Ink and Chemicals) 25 parts,
9.5 parts of phenol novolak (softening point 105 ° C),
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA manufactured by Sanko Chemical) 5
Part, and 0.03 part of 2-phenyl-4-methylimidazole with respect to 100 parts of the total amount of the epoxy resin and the curing agent were dissolved in a mixed solvent of methyl ethyl ketone and methyl cellosolve. The surface-treated spherical fused silica having an average particle size of 0.5 μm was added little by little while stirring with an Ikari type stirring blade. When all the components were mixed, the mixture was stirred for 10 minutes using a high-speed stirrer. A glass cloth (thickness: 180 μm, manufactured by Nitto Boseki) is impregnated with the prepared varnish, dried in a heating furnace at 150 ° C. for 6 minutes, and a varnish solid content (a component in the prepreg, excluding the glass cloth) is about 50% by weight. Prepreg was obtained. A predetermined number of the prepregs were stacked, copper foils having a thickness of 12 μm were stacked on both sides, and heated and pressed at a pressure of 40 kgf / cm ² and a temperature of 190 ° C. for 120 minutes to obtain a double-sided copper-clad laminate.

EXAMPLE 2 1 part of γ-glycidoxypropyltrimethoxysilane was placed in a 3 L separable flask previously containing about 30 parts of methanol as a solvent, and spherical fused silica having an average particle size of 1.5 μm was prepared.
0 parts were added, the mixture was stirred at room temperature for 3 hours, and then the solvent was removed by pressure filtration. The obtained solid content was spread on a vat and dried for 2 hours with an explosion-proof drier, and then treated with a ball mill for 3 hours to break up aggregates. Next, a phenol novolak epoxy resin (Epiclon N-775 manufactured by Dainippon Ink and Chemicals) 1
2.5 parts, bisphenol A novolak epoxy resin (softening point 70 ° C, epoxy equivalent 201) 5 parts, phenol novolak (softening point 105 ° C) 8.5 parts, 9,10-
0.03 of 2-phenyl-4-methylimidazole was added to 3.5 parts of dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA manufactured by Sanko Chemical Co., Ltd.) and 100 parts of epoxy resin and curing agent in total. Was dissolved in a mixed solvent of methyl ethyl ketone and methyl cellosolve, and then subjected to a surface treatment with a coupling agent to give an average particle size of 1.5.
μm spherical fused silica was added little by little while stirring with an irrigating stirring blade. When all the components were mixed, the mixture was stirred for 10 minutes using a high-speed stirrer to prepare a varnish. A glass cloth (thickness: 180 μm, manufactured by Nitto Boseki) is impregnated with the prepared varnish, dried in a heating furnace at 150 ° C. for 6 minutes, and a varnish solid content (a component in the prepreg, excluding the glass cloth) is about 50% by weight. Prepreg was obtained. A predetermined number of the prepregs were stacked, copper foils having a thickness of 12 μm were stacked on both sides, and heated and pressed at a pressure of 40 kgf / cm ² and a temperature of 190 ° C. for 120 minutes to obtain a double-sided copper-clad laminate.

Example 3 0.5 parts of γ- (2-aminoethyl) aminopropyltrimethoxysilane and a silicone oil type coupling agent A (Nihon Unicar, Inc.) were placed in a 3 L separable flask previously containing about 40 parts of methanol as a solvent. MAC2101)
0.1 part and 80 parts of spherical fused silica having an average particle size of 0.5 μm were added and stirred at 90 ° C. for 1 hour to obtain a slurry. Next, tetrakishydroxyphenylethane type epoxy resin (Epicoat E1031S made by Yuka Shell Epoxy) 12.5
Part, phenol novolak (softening point 105 ° C) 5.5
Part, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA manufactured by Sanko Chemical)
0.0 parts of 2-phenyl-4-methylimidazole was added to 1.5 parts and 100 parts of the total amount of the epoxy resin and the curing agent.
After dissolving 3 parts in a mixed solvent of methyl ethyl ketone and methyl cellosolve, the slurry containing the previously prepared spherical silica was added little by little while stirring with an irrigating stirring blade. When all the components have been mixed, 10
The mixture was stirred for a minute to prepare a varnish. Impregnating a glass cloth (thickness: 180 μm, manufactured by Nitto Boseki) using the prepared varnish,
Drying was performed in a heating furnace at 150 ° C. for 6 minutes to obtain a prepreg having a varnish solid content (a component other than glass cloth in the prepreg) of about 50% by weight. A predetermined number of the prepregs are stacked, and a copper foil having a thickness of 12 μm is stacked on both sides, and the pressure is 40 kgf / cm.
^2. Heat and pressure molding was performed at 190 ° C. for 120 minutes to obtain a double-sided copper-clad laminate.

Examples 4 to 14 and Comparative Examples 1 to 6 Double-sided copper-clad laminates were obtained in the same manner as in Examples 1, 2 or 3 using the formulations shown in Tables 1 and 2. However, the surface treatment method of silica was represented by A for the same as Example 1, B for the same as Example 2, and C for the same as Example 3.
The evaluation method is as follows. Tables 1 and 2 show the evaluation results.
Shown in the lower column.

The evaluation method of the obtained double-sided copper-clad laminate is as follows.
The BGA evaluation method is shown in FIG. Glass transition temperature Double-sided copper-clad laminate with a thickness of 0.6 mm is entirely etched,
A test piece of 10 mm × 60 mm was cut out from the obtained laminate, and the temperature was raised at 3 ° C./min using a dynamic viscoelasticity measuring apparatus, and the peak position of tan δ was taken as the glass transition temperature. Coefficient of linear expansion The whole surface of the double-sided copper-clad laminate with a thickness of 1.2 mm is etched,
A test piece of 2 mm × 2 mm was cut out from the obtained laminate, and the linear expansion coefficient in the Z direction was measured at 5 ° C./min using TMA. Flame retardant Double-sided copper-clad laminate with a thickness of 0.6mm is etched over the entire surface,
It measured from the obtained laminated board by UL-94 standard and a vertical method. Solder heat resistance A double-sided copper-clad laminate with a thickness of 0.4 mm was manufactured and JIS C
Eight test pieces were prepared according to the method according to 6481, subjected to a moisture absorption treatment at 125 ° C. for 8 hours in a pressure cooker, and then immersed in a solder bath at 260 ° C. for 120 seconds to determine the number of appearance abnormalities.

Package Warpage A double-sided copper-clad laminate having a thickness of 0.4 mm produced in
Circuit processed for GA. This circuit board (rigid interposer) and the sealing material are EME-7 manufactured by Sumitomo Bakelite.
Using 720, mold temperature 180 ° C, injection pressure 75kg
/ Cm ² , 225 pBGA with a curing time of 2 minutes (package size: 24 × 24 mm, thickness: 1.17 mm, silicon chip size: 9 × 9 mm, thickness: 0.35 mm, chip and bonding pad of circuit board having diameter of 25 μm) (Bonded with a gold wire.) And post-cured at 175 ° C. for 8 hours. After cooling to room temperature, the displacement of the height of the package upper surface was measured diagonally from the gate portion of the package by a surface roughness meter, and the maximum displacement value based on the gate portion was defined as the amount of warpage. The unit is μm. Eight packages obtained by the same method as in the BGA solder crack resistance were left in an environment of 85 ° C. and a relative humidity of 60% for 240 hours.
IR reflow treatment was performed according to the method of C. After the treatment, the presence of peeling and cracks in the inside was observed with an ultrasonic flaw detector, and the number of defective packages was counted. When the number of defective packages is n, it is displayed as n / 8.

The copper-clad laminate obtained by using the epoxy resin composition of the present invention has excellent flame retardancy even though it does not use a halogen compound.
Shows excellent solder heat resistance in package evaluation,
In addition, the warpage after molding is extremely small.

[0024]

[Table 1]

[0025]

[Table 2]

Notes to Table 1) Surface treatment method of silica: A was the same as in Example 1, B was the same as Example 2, and C was the same as Example 3. 2) Silicone oil type coupling agent A: MAC21013 manufactured by Nippon Unicar) Silicone oil type coupling agent B: MAC2301 manufactured by Nippon Unicar 4) Orthocresol novolak epoxy resin: Epichrom N-665 manufactured by Dainippon Ink and Chemicals 5) Phenol novolak epoxy resin : Epicron N-775 manufactured by Dainippon Ink & Chemicals, Inc. 6) Tetrakishydroxyphenylethane type epoxy resin: Epicoat E1031S manufactured by Yuka Shell Epoxy 7) Trishydroxyphenylmethane type epoxy resin:
Eicoat E1032 made by Yuka Shell Epoxy 8) Bisphenol A novolak epoxy resin: softening point 70 ° C, epoxy equivalent 201 9) Bisphenol A type epoxy resin: epoxy equivalent 2
50 10) Phenol novolak: softening point 105 ° C., hydroxyl equivalent 104 10 11) Bisphenol A novolak: softening point 115 ° C.
Hydroxyl equivalent 129 12) Phenol aralkyl resin: XL-2 manufactured by Mitsui Chemicals
25 13) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HC manufactured by Sanko Chemical Co., Ltd.)
A) 14) 2-Phenyl-4-methylimidazole: The amount is based on 100 parts of the total amount of the epoxy resin and the curing agent.

[0027]

The epoxy resin composition of the present invention has excellent flame retardancy without using a halogen-based flame retardant, and has high heat resistance and low thermal expansion characteristics. Therefore, the copper-clad laminate obtained from the epoxy resin composition of the present invention has excellent solder heat resistance and can provide a rigid interposer for an IC package with a small warpage, which can greatly contribute to related industries.

Continued on the front page F-term (reference) 4F072 AA01 AA04 AA05 AA06 AA07 AB09 AB27 AD27 AE01 AE07 AE10 AF06 AF21 AG03 AG14 AG16 AG19 AH02 AH21 AJ04 AK14 AL12 AL13 4J002 CC03X CC06X CD04W CD06W DJ016 EW027AF03 AF00 DC40 FA05 FA12 FB07 FB08 JA08 JA11

Claims (14)

[Claims] (A) an epoxy resin having three or more epoxy groups in one molecule; (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule;
Essential components are (C) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and (D) spherical fused silica having an average particle diameter of 2 μm or less which has been previously surface-treated with a coupling agent. An epoxy resin composition, characterized in that: 2. The coupling agent has two or more repeating units of an epoxy silane coupling agent, an amino silane coupling agent, a ureido silane coupling agent, a mercapto silane coupling agent, a disilazane, a siloxane bond, and an alkoxy group. At least one selected from the group consisting of silicone oil type coupling agents having
The epoxy resin composition according to claim 1, which is a kind of coupling agent. 3. The epoxy according to claim 1, wherein the component (A) is at least one epoxy resin selected from the group consisting of a trishydroxyphenylmethane type epoxy resin, a tetrakishydroxyphenylethane type epoxy resin, and a novolak type epoxy resin. Resin composition. 4. In the component (A), a novolak type epoxy resin (A1) and an epoxy resin (A2) selected from at least one selected from the group consisting of a trishydroxyphenylmethane type epoxy resin and a tetrakishydroxyphenylethane type epoxy resin. The epoxy resin composition according to claim 1, which is essential. 5. The epoxy resin composition according to claim 1, wherein the component (B) is phenol novolak. 6. The composition according to claim 1, wherein the component (D) is mixed in a slurry obtained by mixing spherical fused silica having an average particle diameter of 2 μm or less, a coupling agent and a solvent, and performing a heat reaction. An epoxy resin composition according to any one of the above. 7. A prepreg obtained by impregnating a fiber base material with the epoxy resin composition according to claim 1 and drying it. 8. A copper-clad laminate obtained by heating and molding the prepreg according to claim 7. 9. (A) an epoxy resin having three or more epoxy groups in one molecule, (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule,
(C) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, (D) spherical fused silica having an average particle diameter of 2 μm or less, a coupling agent and a solvent are mixed and reacted by heating. A prepreg, characterized in that a resin varnish containing a slurry as an essential component is applied to a substrate and dried. 10. The coupling agent has two or more repeating units of an epoxy silane coupling agent, an amino silane coupling agent, a ureido silane coupling agent, a mercapto silane coupling agent, a disilazane, and a siloxane bond, and has an alkoxy group. The prepreg according to claim 8, wherein the prepreg is selected from at least one member selected from the group consisting of silicone oil type coupling agents. 11. The composition according to claim 8, wherein the component (A) is at least one epoxy resin selected from the group consisting of a trishydroxyphenylmethane type epoxy resin, a tetrakishydroxyphenylethane type epoxy resin, and a novolak type epoxy resin. Prepreg. 12. The component (A) comprises a novolak epoxy resin (A1) and an epoxy resin (A2) selected from at least one selected from the group consisting of a trishydroxyphenylmethane epoxy resin and a tetrakishydroxyphenylethane epoxy resin. The prepreg according to claim 8, wherein the prepreg is essential. 13. The prepreg according to claim 8, wherein the component (B) is phenol novolak. 14. A copper-clad laminate obtained by heating and molding the prepreg according to claim 8.