JP2002097346A - Epoxy resin composition for interposer, prepreg and copper-clad laminated sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for an interposer having excellent soldering resistance due to high heat resistance, low thermal expansion and low water absorption, a prepreg using the same and a copper-clad laminated sheet. SOLUTION: The epoxy resin composition for an interposer contains (A) an orthocresol novolak resin having a softening point of >=75 deg.C, (B) a curing agent based on a phenolic resin having >=3 phenolic hydroxy groups in a molecule, (C) a flame retardant and (D) a spherical fused silica as essential components. The composition is preferably compounded further with (E) a coupling agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an epoxy resin composition for an interposer having excellent solder resistance due to high heat resistance, low thermal expansion, and low water absorption, and a prepreg and a copper-clad laminate using the same. .

[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. However, a bismaleimide-triazine resin-based substrate used as a current rigid substrate for an interposer has a high water absorption rate, a large linear expansion coefficient, and the solder resistance of an IC package is not always sufficient. On the other hand, in order to reduce the coefficient of thermal expansion of a substrate, it is generally widely used to use an inorganic filler, particularly fused silica, but in the case of conventionally used crushed fused silica, a square shape is used. Therefore, a large stress is applied to the base material and the copper foil during the press molding, and the base material and the copper foil are damaged, and a solder crack may be generated from the damaged portion as a starting point, or the appearance may be deteriorated. .
Japanese Patent Application Laid-Open No. 9-272155 discloses a technique using spherical silica in order to solve such a problem, but does not describe an optimal resin composition for a rigid substrate for an interposer.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and has high heat resistance, low thermal expansion,
An epoxy resin composition for an interposer having excellent solder resistance due to low water absorption, and a prepreg and a copper-clad laminate using the same.

[0004]

SUMMARY OF THE INVENTION The present invention provides a specific epoxy resin and phenolic resin-based curing agent which contributes to heat resistance and low water absorption, a flame retardant, and spherical fused silica exhibiting low thermal expansion and low water absorption. An epoxy resin composition for an interposer contained as an essential component is to be a technical gist,
The above object has been achieved by such a composition.

More specifically, (A) an orthocresol novolak epoxy resin having a softening point of 75 ° C. or higher, (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule, and (C) a hardener An epoxy resin composition for an interposer, comprising a flame retardant and (D) spherical fused silica as essential components, a prepreg obtained by impregnating a base material with these epoxy resin compositions and drying, and using the prepreg. It is a copper-clad laminate formed by heat molding.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION (A) The softening point used in the present invention is 7
Orthocresol novolak epoxy resin having a temperature of 5 ° C. or higher is a polyfunctional epoxy resin for expressing a high glass transition temperature and a high thermal rigidity. Orthocresol novolak epoxy resin usually cannot provide a high glass transition temperature alone and must be combined with other polyfunctional epoxy resin. However, the softening point by the ball ring method of the present invention is 75%.
Orthocresol novolak epoxy resin above ℃
Since the molecular weight is large and the number of epoxy groups contained in one molecule is large on average, a high glass transition temperature can be obtained. Therefore, in the present invention, the low water absorption and the heat resistance of the ortho-cresol novolak epoxy resin are compatible with each other, and a performance excellent in solder crack resistance as an interposer of an IC package is exhibited. 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 amount is less than 10% by weight, the binder component will be reduced even if (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule is combined, and the heat resistance, especially IC
Solder crack resistance as an interposer of the 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 cracking resistance as an interposer means, in a soldering cracking test according to JEDEC mounting rank conditions performed in a BGA or a CSP using a rigid interposer, due to the interposer or indirectly due to the interposer. It means the resistance to cracks or interfacial delamination caused by the influence of the properties. 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.

The phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule of component (B) is exemplified by phenol novolak, bisphenol A novolak, phenol aralkyl resin and the like. Phenol novolak, which has a relatively small equivalent and can easily remove low-functional monomers, and bisphenol A novolak, which can obtain a high glass transition temperature, are preferable. In the present invention, the component (B) is added so that the ratio (equivalent ratio) of the number of moles of the epoxy group of the epoxy resin to the number of moles of the phenolic hydroxyl group of the component (B) becomes 0.8 or more and 1.2 or less. Is preferred. Outside this range, a decrease in the glass transition temperature and an increase in the water absorption may cause a decrease in the solder crack resistance, particularly as an interposer of the IC package, and a decrease in the humidity resistance of the IC.

[0008] The component (C) flame retardant used in the present invention is not particularly limited as long as it contributes to flame resistance. However, when it is applied to a product in which halogen is not a problem,
A brominated epoxy resin such as a brominated phenol novolak epoxy resin or a brominated bisphenol A type epoxy resin is suitable because it has excellent solder crack resistance as an IC package interposer and excellent moisture resistance reliability of the IC. In a brominated epoxy resin, the amount of bromine required for flame retardation varies depending on the amount of the resin component. The amount of bromine in the epoxy resin composition is usually 0.5% by weight to 20% by weight.
% By weight or less. Those which are required to be halogen-free include phosphoric acid esters, red phosphorus, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-
Examples thereof include 10-oxide (hereinafter abbreviated as HCA), phosphorus-based flame retardants such as triarylphosphine oxide, phosphazene, and the like. Solder crack resistance as an interposer for an IC package and moisture resistance reliability of the IC are maintained. Preferably, HCA or a combination of HCA and triarylphosphine oxide is used.

HCA is a reactive phosphorus compound in which hydrogen bonded to phosphorus reacts with an epoxy group, and is an excellent phosphorus compound which is not hydrolyzed to increase water absorption or reduce adhesion. It is a flame retardant. However, on the other hand, since this compound has an effect of delaying the curability of the resin, there is a case where a problem occurs in the curability when the press molding time is shortened. In that case, a combination use of HCA and triarylphosphine oxide is preferred. Examples of the triarylphosphine oxide include triphenylphosphine oxide, trishydroxyphenylphosphine oxide, bis (hydroxyphenyl) phenylphosphine oxide, trisaminophenylphosphine oxide, and bis (aminophenyl) phenylphosphine oxide. The aryl group of the oxide may be unsubstituted or may have any substituent.

[0010] Triarylphosphine oxide is considered not to react with the matrix resin or to have low reactivity. However, triarylphosphine oxide has excellent hydrolysis resistance and, in addition, HC
It does not affect the curability unlike A. Therefore HCA
When the compound is used together with triarylphosphine oxide, good solder heat resistance can be realized without deteriorating water absorption and adhesion while maintaining flame retardancy and curability. The added weight ratio of HCA and triarylphosphine oxide is 1: 4 to 4: 1.
Is preferred. Outside of this range, the combined effect may be diminished. The total addition amount of HCA or HCA and triarylphosphine oxide is preferably 0.5 to 10% by weight based on the entire epoxy resin composition. 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 may be lowered, the water absorption may be increased, or the adhesion may be reduced to cause a decrease in solder crack resistance. is there.

The component (D) spherical fused silica used in the present invention is an important component for reducing the water absorption, reducing the coefficient of linear expansion, and improving the solder crack resistance of the interposer which is a constituent material of the IC package. . In the case of crushed fused silica, when the filler is sandwiched in a relatively narrow gap between the glass base material and the copper foil constituting the copper-clad laminate, the shape is angular, It gives stress, damages them, solder cracks may occur from the damaged part, or the appearance may deteriorate,
In addition, when a large amount of filler is used, the fluidity decreases.

In the case of spherical fused silica, the particle size, particle size distribution,
Regardless of the specific surface area, stress on the substrate and copper foil is smaller than that of crushed fused silica, but among them, the average particle size is 5μ.
In the case of spherical fused silica having a particle size of m or less (in the present invention, the particle diameters are all measured by a laser diffraction particle size distribution measurement), the stress on the base material and the copper foil is preferably smaller. If the average particle size exceeds 5 μm, the stress on the base material and the copper foil gradually increases, and the solder crack resistance may deteriorate. Maximum particle size of 24μ among spherical fused silica with an average particle size of 5μm or less
m, average particle diameter of 2 μm or more and 5 μm or less, and BET
Spherical fused silica having a specific surface area of 5 m ² / g or less,
Alternatively, spherical fused silica having an average particle diameter of 2 μm or less, which has been surface-treated with a coupling agent in advance, is more preferable because stress on the substrate and copper foil is extremely small, and aggregation is small and the filler is uniformly dispersed. Maximum particle size is 24μ
When coarse particles exceeding m are included, a space is created between the copper foil and the base material due to the coarse particles, and when moisture is absorbed, water stays there to deteriorate solder crack resistance, and the appearance of the copper-clad laminate May worsen. When the average particle size is smaller than 2 μm or when the specific surface area exceeds 5 m ² / g, the same problem as the case where the coarse particles are contained may occur due to secondary aggregation of the particles.

It is preferable to use the spherical fused silica component (D) which has been surface-treated with a coupling agent in advance, since the aggregation is small and the filler is uniformly dispersed. Examples of the coupling agent to be used include a silane coupling agent, a silicon-based coupling agent such as a silicone oil-type coupling agent having two or more siloxane bond repeating units and having an alkoxy group, and a titanate-based coupling agent. However, silicon-based coupling agents are preferred from the viewpoint of improving the wettability of the surfaces of the epoxy resin and the fused spherical silica. 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 this case, the proportion of the coupling agent is generally 0.1 to 10 parts by weight based on 100 parts by weight of the spherical fused silica.

Spherical fused silica surface-treated with a coupling agent in advance has an average particle size of 2 μm or less. In addition to the fact that the filler is less agglomerated and the filler is uniformly dispersed, stress on the base material and copper foil is extremely low. It is more preferable because it is small. Also,
For the same reason, spherical fused silica has a maximum particle size of 24 μm.
m or less, a spherical fused silica having an average particle diameter of 2 μm or more and 5 μm or less, and a specific surface area of 5 m ² / g or less, and a spherical fused silica having an average particle diameter of 2 μm or less previously surface-treated with a coupling agent may be used in combination. This is one of preferred embodiments. When a coupling agent is used, it is known to those skilled in the art to add a small amount of water or to use an acid or alkali to promote the reaction between the silanol on the silica surface and the coupling agent, and is included in the present invention. .

Component (D) spherical fused silica is preferred if it accounts for at least 50% by weight of the epoxy resin composition, since thermal expansion and water absorption are reduced. However, if the content exceeds 90% by weight, the proportion of the filler in the epoxy resin composition is too large, and operations such as impregnation become difficult.

In the present invention, in addition to the above-mentioned coupling agent, the use of the component (E) coupling agent together with other components at the time of compounding the raw materials is dependent on whether or not the spherical silica has been surface-treated in advance. This is advantageous because it has an effect on uniform dispersion of spherical fused silica and prevention of aggregation. Examples of the coupling agent to be used are the same as those used for the surface treatment of the component (D) spherical fused silica. The proportion of the coupling agent (E) in the epoxy resin composition is preferably from 0.05 to 10% by weight. If the amount is less than 0.05% by weight, the coupling agent may not be dispersed on the entire surface of the filler. If it exceeds 10% by weight, the glass transition temperature may decrease.

The epoxy resin composition of the present invention may optionally contain additives other than the above components as long as the properties are not impaired. The prepreg can be obtained by applying and impregnating the epoxy resin composition of the present invention as a varnish using a solvent or a solvent-free fiber substrate, followed by drying. As the substrate, a glass woven fabric, a glass nonwoven fabric, or another organic substrate can be used. One or more of these prepregs are heat-formed together with copper foil to obtain a copper-clad laminate. These prepregs and copper-clad laminates are also included in the present invention.

[0018]

EXAMPLE 1 17.5 parts (parts by weight, hereinafter the same) of orthocresol novolak epoxy resin having a softening point of 76 ° C., brominated phenol novolak epoxy resin (epoxy equivalent: 284, softening point: 84 ° C., bromine content: 35% by weight) %) 10 parts, phenol novolak (softening point 105 ° C) 6 parts, bisphenol A novolak (softening point 115 ° C, hydroxyl equivalent 129) 6.5
Parts and a total of 100 parts of the epoxy resin and the curing agent, 0.03 part of 2-phenyl-4-methylimidazole was dissolved in a mixed solvent of methyl ethyl ketone and methyl cellosolve, and γ-glycidoxypropyl was added to the solution. 0.5 parts of trimethoxysilane is added and stirred, and subsequently, spherical fused silica having an average particle size of 2.5 μm (spherical fused silica having an average particle size of 2.5 μm and a specific surface area of 4.5 m ² / g cut from 24 μm or more) 60 parts were added little by little while stirring with a stirrer. 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 are stacked, and a copper foil having a thickness of 12 μm is
Heat and pressure molding was performed at 0 kgf / cm ² and a temperature of 190 ° C. for 120 minutes to obtain a double-sided copper-clad laminate.

Example 2 70 parts of spherical fused silica having an average particle size of 0.5 μm was charged into a Henschel mixer, and a 10% by weight solution of γ-glycidoxypropyltrimethoxysilane in methanol 1 was stirred.
0 parts were added little by little. After completion of the addition, the mixture was stirred for 5 minutes and taken out. Next, 12.5 parts of ortho-cresol novolak epoxy resin having a softening point of 85 ° C, 8 parts of brominated phenol novolak epoxy resin (epoxy equivalent: 284, softening point: 84 ° C, bromine content: 35% by weight), and phenol novolak (softening point: 105 ° C) After dissolving 0.03 parts of 2-phenyl-4-methylimidazole in a mixed solvent of methyl ethyl ketone and methyl cellosolve with respect to 9.5 parts and 100 parts of the total amount of the epoxy resin and the curing agent, γ- (2-amino ethyl)
0.1 part of aminopropyltrimethoxysilane was added, followed by an average particle size of 0.5 previously treated with a coupling agent.
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 4 70 parts of spherical fused silica having an average particle size of 1.5 μm was put into a Henschel mixer, and a 10% by weight solution of γ-glycidoxypropyltrimethoxysilane in methanol 8 was stirred.
And 1 part of a 10% by weight solution of a silicone oil-type coupling agent A (MAC2101 manufactured by Nippon Unicar) in methanol was added little by little. After completion of the addition, the mixture was stirred for 5 minutes and taken out. Next, 14 parts of orthocresol novolak epoxy resin having a softening point of 76 ° C., 6 parts of brominated phenol novolak epoxy resin (epoxy equivalent: 284, softening point: 84 ° C., bromine content: 35% by weight), and phenol novolak (softening point: 10%)
5 parts), bisphenol A novolak (softening point 11)
After dissolving 0.03 part of 2-phenyl-4-methylimidazole in a mixed solvent of methyl ethyl ketone and methyl cellosolve with respect to 5 parts of 5 ° C., hydroxyl equivalent 129) and 5 parts of epoxy resin and curing agent in total of 100 parts, Spherical fused silica surface-treated with a coupling agent and having an average particle size of 1.5 μm 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 3, 5 to 14 and Comparative Examples 1 to 5 In the formulations shown in Tables 1 and 3, in the method of adding the coupling agent in the table, A is the same as in Example 1, and B is the In the method of Example 2, C was prepared in the same manner as in Example 4 to prepare a varnish to obtain a double-sided copper-clad laminate. Example 6 is an example in which no coupling agent is used. Comparative Example 1 was a bismaleimide-triazine resin (BT resin manufactured by Mitsubishi Gas Chemical,
CCL-HL830).

Examples 15 to 21 In the formulation shown in Table 2, in the method of adding the coupling agent in the table, A is the same as in Example 1, B is the same as in Example 2, and C is the same as in Example 2. A varnish was prepared in the same manner as in Example 4, and the press time was changed from 120 minutes to 60 minutes to obtain a double-sided copper-clad laminate.

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.

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 solder crack resistance were left in an environment of 85 ° C. and a relative humidity of 60% for 192 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 evaluation results are shown in Tables 1, 2, 3 and the lower column of Table 4. The interposer using the epoxy resin composition of the present invention has excellent resistance to solder cracking, and also has extremely small warpage after molding.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

Notes to Table 1) A: Method of using the same coupling agent as in Example 1 B: Method of using the same coupling agent as in Example 2 C: Method of using the same coupling agent as in Example 4 2) 24 μm Spherical fused silica with an average particle size of 2.5 μm cut from the above, specific surface area 4.5 m ² / g 3) Spherical fused silica with an average particle size of 4 μm cut from 24 μm or more, specific surface area 4 m ² / g 4) 24 μm or more 5) Spherical fused silica having an average particle size of 8 μm in which coarse particles are not cut 5) Spherical fused silica having an average particle size of 11 μm in which coarse particles of 24 μm or more are not cut 8) γ-glycidoxypropyltrimethoxysilane diluted with methanol 10% by weight solution 7) Silicone oil type coupling agent A: MAC2101 manufactured by Nippon Unicar 8) Silicone oil type coupling agent A diluted with methanol 0% by weight solution 9) Silicone oil type coupling agent B: MAC2301 manufactured by Nippon Unicar 10) Bisphenol A type epoxy resin: Epoxy equivalent 250 11) Brominated phenol novolak epoxy resin: Epoxy equivalent 284, softening point 84 ° C, bromine content 35 Weight% 12) phenol novolak: softening point 105 ° C, hydroxyl equivalent 104 104 13) bisphenol A novolak: softening point 115 ° C,
14) phenol aralkyl resin: XL-2 manufactured by Mitsui Chemicals, Inc.
25 15) 2-Phenyl-4-methylimidazole: The amount is based on 100 parts of the total amount of the epoxy resin and the curing agent. 16) 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (3 Photochemical HC
A) 17) Brominated bisphenol A type epoxy resin: epoxy equivalent 365, bromine content 46% by weight

[0031]

The epoxy resin composition for an interposer of the present invention has excellent properties such as high heat resistance, low thermal expansion, and low water absorption. The copper-clad laminate obtained from the epoxy resin composition of the present invention has a solder resistant property. It is possible to provide a substrate for an IC package having excellent performance and a small warpage, which can greatly contribute to related industries.

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Claims (14)

[Claims] 1. An orthocresol novolak epoxy resin having a softening point of 75 ° C. or higher, (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule, (C) a flame retardant, and (D) An epoxy resin composition for an interposer, comprising spherical fused silica as an essential component. 2. (A) an ortho-cresol novolak epoxy resin having a softening point of 75 ° C. or higher, (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule, (C) a flame retardant, An epoxy resin composition for an interposer, comprising D) spherical fused silica and (E) a coupling agent as essential components. 3. The epoxy resin composition for an interposer according to claim 1, wherein the component (B) is phenol novolak or bisphenol A novolak. 4. Component (D) having a maximum particle size of 24 μm or less,
Average particle size of 2 μm or more and 5 μm or less, and specific surface area of 5 m ²
The epoxy resin composition for an interposer according to any one of claims 1 to 3, wherein the epoxy resin composition is spherical fused silica of not more than / g. 5. The epoxy resin composition for an interposer according to claim 1, wherein the component (D) is spherical fused silica surface-treated with a coupling agent in advance. 6. The epoxy resin composition for an interposer according to claim 5, wherein the component (D) is spherical fused silica having an average particle size of 2 μm or less. 7. Component (D) having a maximum particle size of 24 μm or less,
Average particle size of 2 μm or more and 5 μm or less, and specific surface area of 5 m ²
The epoxy resin composition for an interposer according to any one of claims 1 to 3, comprising spherical fused silica having an average particle diameter of 2 µm or less and surface-treated with a coupling agent in advance. 8. The coupling agent for surface-treating the spherical fused silica used in the component (D) in advance includes epoxysilane coupling agent, aminosilane coupling agent, ureidosilane coupling agent, mercaptosilane coupling agent, disilazane, and siloxane. The epoxy resin composition for an interposer according to claim 5, 6 or 7, which is at least one coupling agent selected from the group consisting of a silicone oil type coupling agent having two or more bonding repeating units and having an alkoxy group. object. 9. Component (E) 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 an alkoxy group The epoxy resin composition for an interposer according to any one of claims 2 to 8, which is at least one coupling agent selected from the group consisting of a silicone oil type coupling agent having: 10. The epoxy resin composition for an interposer according to claim 1, wherein the flame retardant is a brominated epoxy resin. 11. The epoxy resin composition for an interposer according to claim 1, wherein the flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. 12. The flame retardant of claim 1, wherein the flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and triarylphosphine oxide.
10. The epoxy resin composition for an interposer according to any one of claims to 9. 13. A prepreg obtained by impregnating and drying a fiber base material with the epoxy resin composition for an interposer according to claim 1. 14. A copper-clad laminate obtained by heating and molding the prepreg according to claim 13.