WO2005023933A1

WO2005023933A1 - Thermosetting resin composition for high speed transmission circuit board

Info

Publication number: WO2005023933A1
Application number: PCT/KR2004/002200
Authority: WO
Inventors: Hyuk-Sung Chung; Bong-Jin Jeon; Hyun-Cheol Kim; Eun-Hae Koo
Original assignee: LG Chem Ltd
Current assignee: LG Chem Ltd
Priority date: 2003-09-05
Filing date: 2004-09-01
Publication date: 2005-03-17
Anticipated expiration: 2006-03-05
Also published as: US20050080183A1; US7255925B2; KR20050024871A; JP2006518774A; TW200523319A; TWI297346B; CN1701093A; KR100561070B1; CN100340604C

Abstract

The present invention relates to a thermosetting resin composition for a high speed transmission circuit board, more particularly to a thermosetting resin composition having superior dielectric characteristics with low dielectric constant and dissipation factor and having superior glass transition temperature, heat resistance after moisture absorption, dielectric reliability, adhesion to copper film, workability, dispersibility of inorganic filler, electric characteristics, etc., and thus being useful for a copper clad laminate for high speed signal transfer.

Description

TITLE OF THE INVENTION

THERMOSETTING RESIN COMPOSITION FOR HIGH SPEED

TRANSMISSION CIRCUIT BOARD

BACKGROUND OF THE INVENTION

(a) Field of the invention

The present invention relates to a thermosetting resin composition for a

high speed transmission circuit board, more particularly to a thermosetting resin

composition having superior dielectric characteristics with low dielectric constant

and dissipation factor and having superior glass transition temperature, heat

resistance after moisture absorption, dielectric reliability, adhesion to copper film,

workability, dispersibility of inorganic filler, electric characteristics, etc., and thus

being useful for a copper clad laminate for high speed signal transfer.

(b) Description of the Related Art Recently, electronic devices such as computers and communication

devices, etc. are being more highly integrated and multilayered. And, mobile

phones, notebook computers, etc. are becoming more small-sized, light and

capable. As printed circuit boards mounted on these devices are becoming

more integrated and compact, superior heat resistance and dielectric reliability

are required. With the development of high speed communication services,

signal delay and transmission loss of high speed transmission circuit boards

mounted on communication devices are emerging as problem. Because the signal delay is proportional to the square root of the dielectric constant of an

insulator and the transmission loss is proportional to the dielectric constant of the

insulator and the dissipation factor, a material having low dielectric constant and

dissipation factor is required for a high speed transmission circuit board. In the conventional FR-4 printed circuit board, an epoxy resin

composition comprising a brominated difunctional epoxy resin, a multifunctional

epoxy resin, an amine based curing agent, an imidazole curing accelerator, etc.

is used. The polar groups resultant from the reaction of the epoxy resin and the

amine based curing agent increase the dielectric constant and the dissipation

factor, so that it is impossible to obtain transmission characteristics sufficient for

high speed transmission.

In order to solve this problem, Korea Laid-Open Publication No. 2002-

0044342 discloses a method of using an acid anhydride based epoxy curing

agent and Korea Laid-Open Publication No. 2002-0085475 discloses a method

of using a dicyclopentadiene based epoxy resin, which has low dielectric

constant. However, epoxy resin is limited in offering sufficiently low dielectric

constant and dissipation factor required for high speed and high frequency

transmission.

Thus, use of a thermoplastic resin such as a fluorine based resin,

polyphenylene ether, etc. or a composite resin of polyphenylene ether and epoxy

resin, which have low dielectric constant and dissipation factor, has been

proposed. However, these resins require high temperature and pressure for processing because of high melting point or softening point and have inferior

processing characteristics and adhesion to copper film.

Use of a cyanate ester resin, which has the lowest dielectric constant

among thermosetting resins, offers low dielectric constant and dissipation factor.

But, the dielectric reliability worsens because triazine, which is included in the

resin, has poor heat resistance after moisture absorption.

In order to solve this problem, Japanese Patent Publication No. 2000-

239496 discloses a method of mixing a cyanate ester resin with a

dicyclopentadiene based epoxy resin, which has low dielectric constant and

dissipation factor, to reduce dielectric constant and dissipation factor and

improve heat resistance after moisture absorption. However, this method does

not offer electric characteristics sufficient for a high speed transmission circuit

board.

In order to improve dielectric characteristics and heat resistance after

moisture absorption of cyanate ester, U.S. Patent No. 6,162,876, U.S. Patent No.

6,245,841 , Japanese Laid-Open Publication No. 1999-21507 and Japanese

Laid-Open Publication No. 1999-21453 disclose a method of decreasing

dielectric constant and dissipation factor by mixing a phenol-modified cyanate

ester oligomer with polyphenylene ether. However, this method is also limited

in that the heat resistance after moisture absorption worsens. Japanese Laid-

Open Publication No. 1999-263940 discloses a method of mixing a phenol-

modified cyanate ester oligomer with a cyclic olefin copolymer and Japanese Laid-Open Publication No. 2001-214053 discloses a method of mixing a phenol-

modified cyanate ester oligomer with polystyrene. However, these methods are

limited in that the heat resistance after moisture absorption and the adhesion to

copper film is very low because of insufficient compatibility with cyanate ester. Japanese Laid-Open Publication No. Sho 63-33505 discloses a method

of adding an inorganic filler to improve the performance of a clad laminate.

However, as the inorganic filler is mixed with varnish, the filler is slowly

deposited in an impregnation tank during prepreg preparation, and thereby

worsens workability. Also, the appearance of the prepreg becomes poor, the

dispersibility of the inorganic filler becomes non-uniform, so that the interfacial

adhesion of the clad laminate, drilling characteristics and insulating

characteristics worsen.

Japanese Laid-Open Publication No. 2001-339130 discloses a method

of improving dispersibility of the inorganic filler, offering the clad laminate

formability and processing characteristics comparable to those of an epoxy resin

and improving heat resistance and dielectric reliability by adding an inorganic

filler treated with a silicon polymer having an hydroxyl group to a cyanate ester

resin and polyphenylene ether. However, this method requires an additional

process of treating the inorganic filler with the silicon polymer. And, the content

of the inorganic filler should be increased to increase heat resistance after

moisture absorption of the clad laminate, which increases the viscosity of varnish

and thus makes the processing difficult. Accordingly, a thermosetting resin having superior dielectric

characteristics with low dielectric constant and dissipation factor and being

capable of improving heat resistance after moisture absorption and dispersibility

of inorganic filler is necessary.

SUMMARY OF THE INVENTION

It is an aspect of the present invention to provide a thermosetting resin

and dissipation factor and being capable of greatly improving glass transition

temperature, heat resistance after moisture absorption, dielectric reliability,

adhesion to copper film, workability, dispersibility of inorganic filler, electric

characteristics, etc.

It is another aspect of the present invention to provide a copper clad

laminate for high speed signal transfer capable of reducing dielectric constant

and dissipation factor and offering superior heat resistance after moisture

absorption, dielectric reliability, adhesion to copper film, electric characteristics,

etc. and suitable for multilayering and high speed signal transfer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To attain the aspects, the present invention provides a thermosetting

resin composition for a high speed transmission circuit board comprising: a) a cyanate ester based resin having at least two cyanate groups in one

molecule; b) a dicyclopentadiene based epoxy resin; c) a fumed silica; d) a thermoplastic resin; e) a cyanate ester resin curing accelerator; f) an epoxy resin curing accelerator; g) a primary phenolic compound; and h) a flame retardant.

The present invention also provides a copper clad laminate for high

speed signal transfer comprising the thermosetting resin composition.

Hereinafter, the present invention is described in more detail. The present inventors worked on a thermosetting resin having superior

dielectric characteristics with low dielectric constant and dissipation factor and

being capable of improving heat resistance after moisture absorption and

dispersibility of inorganic filler. In doing so, they found out that dielectric

constant and dissipation factor are reduced and glass transition temperature,

heat resistance after moisture absorption, dielectric reliability, adhesion to

copper film, workability, dispersibility of inorganic filler, electric characteristics,

etc. are significantly improved by mixing a cyanate ester based resin having at

least two cyanate groups in one molecule, a dicyclopentadiene based epoxy

resin, a fumed silica and a thermoplastic resin. The present invention is characterized by a thermoplastic resin

composition for a circuit board for high speed signal transfer comprising a

cyanate ester based resin having at least two cyanate groups in one molecule, a dicyclopentadiene based epoxy resin, a fumed silica, a thermoplastic resin, a

cyanate ester resin curing accelerator, an epoxy resin curing accelerator, a

primary phenolic compound and a flame retardant.

Preferably, the thermosetting resin composition for a high speed

transmission circuit board of the present invention comprises: a) 100 parts by weight of a cyanate ester based resin having at least two

cyanate groups in one molecule; b) 50 to 300 parts by weight of a dicyclopentadiene based epoxy resin; c) 0.5 to 10 parts by weight of a fumed silica per 100 parts by weight of

the cyanate ester based resin and the dicyclopentadiene based epoxy resin; d) 5 to 100 parts by weight of a thermoplastic resin; e) 5 to 300 ppm of a cyanate ester resin curing accelerator; f) 0.05 to 3 parts by weight of an epoxy resin curing accelerator per 100

parts by weight of the dicyclopentadiene based epoxy resin; g) 1 to 30 parts by weight of a primary phenolic compound; and h) 5 to 50 parts by weight of a flame retardant per 100 parts by weight of

the cyanate ester based resin and the dicyclopentadiene based epoxy resin.

Preferably, a) the cyanate ester based resin having at least two cyanate

groups in one molecule is a compound represented by Formula 1 below:

where

each of R₂, R₃, R₄ and R₅ is hydrogen or CH₃.

Specifically, the cyanate ester based resin having at least two cyanate

groups in one molecule may be 2,2-bis(4-cyanatephenyl)propane, bis(3,5-

dimethyl-4-cyanatephenyl)methane, 2,2-bis(4-cyanatephenyl)-1 , 1 ,1 , 3,3,3-

hexafluoropropane, etc.

Preferably, the cyanate ester based resin having at least two cyanate

groups in one molecule is prepolymerized from a monomer. If the monomer is

treated with varnish, impregnation may become impossible due to

recrystallization. Thus, the content of the monomer is preferably 10 to 70 mol%,

more preferably 30 to 60 mol%. If the content of the monomer is below 10

mol%, recrystallization may occur. Otherwise, if it exceeds 70 mol%, the

varnish becomes too viscous, so that impregnation becomes difficult and storage

stability of the varnish worsens. b) The dicyclopentadiene based epoxy resin, which is represented by

Formula 2 below, has a hydrophobic bicyclic hydrocarbon group with less

polarization, and thus has superior dielectric characteristics.

In Formula 2, n is 0 or a positive integer.

Preferably, the dicyclopentadiene based epoxy resin is comprised in 50

to 300 parts by weight per 100 parts by weight of the cyanate ester based resin.

If the content is below 50 parts by weight, heat resistance may worsen after

moisture absorption. Otherwise, if it exceeds 300 parts by weight, dielectric

characteristics may worsen. c) The fumed silica, a porous nano-sized silica particle, solves the

dispersibility problem of the micro-sized silica.

Preferably, the fumed silica has an average diameter ranging from 1 to

100 nm.

Preferably, the fumed silica is comprised in 0.5 to 10 parts by weight per

100 parts by weight of the cyanate ester based resin and the dicyclopentadiene

based epoxy resin. If the content is below 0.5 part by weight, heat resistance

after moisture absorption may worsen. Otherwise, if it exceeds 10 parts by

weight, the varnish becomes too viscous, so that impregnation becomes difficult.

For d) the thermoplastic resin, polystyrene, cyclic olefin copolymer,

polyphenylene ether, polyphenylene ether having an epoxy group, etc., which

has superior dielectric characteristics, may be used. Preferably, the thermoplastic resin is comprised in 5 to 100 parts by

weight per 100 parts by weight of the cyanate ester based resin. If the content

is below 5 parts by weight of, it is impossible to obtain ideal dielectric

characteristics. Otherwise, if it exceeds 100 parts by weight, heat resistance

after moisture absorption is significantly reduced and adhesion to metal film also

worsens. e) The cyanate ester resin curing accelerator acts as a catalyst

promoting curing of the cyanate ester based resin.

For the cyanate ester resin curing accelerator, an organometal or an

organometallic complex, specifically with iron, copper, zinc, cobalt, nickel,

manganese, tin, etc. may be used. For the organometal, iron naphthenate,

copper naphthenate, zinc naphthenate, cobalt naphthenate, iron octanoate,

copper octanoate, zinc octanoate, cobalt octanoate, etc. may be used. And, for

the organometallic complex, lead acetylacetonate, cobalt acetylacetonate, etc.

may be used.

Preferably, the cyanate ester resin curing accelerator is comprised in 5

to 300 ppm, more preferably in 10 to 200 ppm, per 100 parts by weight of the

cyanate ester based resin, based on the metal concentration. If the content is

below 5 ppm, reactivity and curing characteristics may be insufficient.

Otherwise, if it exceeds 300 ppm, reaction control becomes difficult, so that

curing happens too fast or forming characteristics may worsen.

For g) the epoxy resin curing accelerator, imidazole derivatives such as 1-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-

phenylimidazole, 2-cyclohexyl-4-methylimidazole, 4-butyl-5-ethylimidazole, 2-

methyl-5-ethylimidazole, 2-octyl-4-hexylimidazole, 2,5-chloro-4-ethylimidazole,

etc. may be used. Preferably, the epoxy resin curing accelerator is comprised in 0.05 to 3

parts by weight per 100 parts by weight of the dicyclopentadiene based epoxy

resin. If the content is below 0.05 part by weight, catalytic activity decreases,

so that curing time increases. Otherwise, if it exceeds 3 parts by weight,

storage stability of varnish or prepreg may worsen significantly. f) The primary phenolic compound functions as cocatalyst in the curing

of the cyanate ester based resin and reduces dielectric constant and dissipation

factor. As the cyanate ester based resin is cured, a triazine is formed and

unreacted cyanate reacts with the primary phenolic compound to form imide

carbonate, thereby reducing polarity and thus reducing dielectric constant and

dissipation factor.

The primary phenolic compound is a compound represented by Formula

3 below:

where each of R₆ and R₇ is hydrogen or CH₃ independently; and n is 1 or 2.

For the primary phenolic compound, nonylphenol, dinonylphenol,

octylphenol, 4-cumylphenol, etc., which has superior heat resistance, may be

used.

The primary phenolic compound is preferably comprised in 1 to 30 parts

by weight, more preferably in 5 to 25 parts by weight, per 100 parts by weight of

the cyanate ester based resin. If the content is below 1 part by weight,

dielectric characteristics may worsen. Otherwise, if it exceeds 30 parts by

weight, heat resistance may worsen.

For h) the flame retardant, a hydrocarbon based less polar compound

not inhibiting curing of the cyanate ester based resin and not reducing dielectric

characteristics, such as 1 ,2-dibromo-4-(1 ,2-dibromoethyl)cyclohexane,

tetrabromocyclohexane, hexabromocyclodecane, etc., may be used.

Particularly, it is preferable to use 2,4,6-tris(tribromophenoxy)-1 ,3,5-

triazine represented by Formula 4 below, which is highly compatible with a

structure similar to that of the cyanate ester based resin, for the flame retardant.

Preferably, the flame retardant is comprised in 5 to 50 parts by weight

per 100 parts by weight of the cyanate ester based resin and the

dicyclopentadiene based epoxy resin, in the range of having a flame retardance

of UL-V0 level. If the content is below 5 parts by weight, flame retardance may

be insufficient. Otherwise, if it exceeds 50 parts by weight, heat resistance may

be insufficient.

The thermosetting resin composition of the present invention can reduce

dielectric constant and dissipation factor and improve heat resistance after

moisture absorption, adhesion to copper film and dispersibility of inorganic filler

by adding the fumed silica and the thermoplastic resin to the cyanate ester

based resin and the dicyclopentadiene based epoxy resin.

The present invention also provides a copper clad laminate for high

speed signal transfer comprising the thermosetting resin composition by

dissolving or dispersing the thermosetting resin composition in a solvent,

impregnating the composition in a substrate and drying it at 80 to 200 °C for a

given time to prepare a prepreg for a printed circuit board without B stage

adhesivity. For the substrate, the common woven or nonwoven fiber substrate

can be used. For the fiber substrate, an inorganic fiber such as glass, alumina,

asbestos, boron, silica alumina glass, silica glass, silicon carbide, silicon nitride,

etc. or an organic fiber such as aramid, polyether ketone, polyether imide,

cellulose, etc. may be used. Especially, a glass woven fiber is preferable. The

prepreg is laminated to at least one layer and then a metal film is formed on one or both sides. Then, it is heated, pressed and molded into a copper clad

laminate for high speed signal transfer.

Hereinafter, the present invention is described in more detail through

examples. However, the following examples are only for the understanding of

the present invention and they do not limit the present invention.

EXAMPLES

Example 1

(Preparation of epoxy resin composition) 40 phr of polyphenylene ether (HPP820, GE) was added to 200 phr of

toluene contained in a beaker and was completely dissolved. Then, 7 phr of

fumed silica (Aerosil R972, Degussa) was added to the solution. After stirring

for about 1 hour, 60 phr of 2,4,6-tris(tribromophenoxy)-1 ,3,5-triazine (SR-245H,

Dai-lchi Kogyo Seiyaku) and 20 phr of 4-cumylphenol were added as flame

retardant and primary phenolic compound, respectively, and dissolved. Then,

100 phr of 2,2-bis(4-cyanatephenyl)propane prepolymer (BA230S, Lonza) was

added as cyanate ester based resin and dissolved, and then 100 phr of

dicyclopentadiene epoxy resin (XD-1000L, Nippon Chemicals) was dissolved.

After the constituents were completely dissolved, 0.01 phr of cobalt

acetylacetonate and 0.5 phr of 2-ethyl-4-methylimidazole were added as cyanate

ester based resin curing accelerator and epoxy resin curing accelerator,

respectively. The solution was stirred until the constituents were completely

dissolved to obtain a thermoplastic resin composition. (Preparation of copper clad laminate for high speed signal transfer) The resultant thermoplastic resin composition was impregnated in a

glass fiber and dried at 80 to 200 ^°C to obtain a prepreg for a printed circuit

board without B stage adhesivity. The prepreg was placed on each side of a 35

m-thick copper film and heated and pressed with a vacuum press to prepare a

copper clad laminate for high speed signal transfer.

Example 2

A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for using 100 phr of tetra-o-m ethyl bisphenol F dicyanate prepolymer (ME240S,

Lonza) as cyanate ester based resin.

Example 3

A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for using 80 phr of 2,2-bis(4-cyanatephenyl)propane prepolymer as cyanate

ester resin, 120 phr of dicyclopentadiene epoxy resin, 10 phr of fumed silica,

0.008 phr of cyanate ester resin curing accelerator, 0.6 phr of epoxy resin curing

accelerator and 15 phr of primary phenolic compound.

Example 4 A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for using 40 phr of polystyrene (15NFI, LG) instead of polyphenylene ether. Comparative Example 1

A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for not using a fumed silica.

Comparative Example 2

A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for using 10 phr of a spherical silica (SFP-30M, Denka) instead of a fumed silica.

Comparative Example 3 A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for using 10 phr of a planar silica (MN-U-SIL5, US Silica) instead of a fumed

silica.

Comparative Example 4 A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for using 100 phr of a cresol novolak epoxy resin (N673, Bakelite) instead of a

dicyclopentadiene based epoxy resin.

Comparative Example 5 A thermoplastic resin composition and a copper clad laminate for high

speed signal transfer were prepared in the same manner of Example 1 , except

for using 15 phr of a fumed silica and 150 phr of polyphenylene ether. For each copper clad laminate for high speed signal transfer prepared in

Examples 1 to 4 and Comparative Examples 1 to 5, glass transition temperature,

heat resistance after moisture absorption, dielectric characteristics, and

adhesion to copper film were measured as follows. The result is given in Table

2 below. a) Glass transition temperature (T_g, ^°C) - Copper film was removed from

each copper clad laminate for high speed signal transfer prepared in Examples 1

to 4 and Comparative Examples 1 to 5 using an etching solution. The sample

was heated to 250 ^°C at a rate of 10 ^°C/min using a DSC (differential scanning

calorimeter). It was cooled to 30 ^°C and then heated to 300 ^°C at a rate of

10 ^°C/min to measure the glass transition temperature. b) Heat resistance after moisture absorption - Each copper clad

laminate for high speed signal transfer prepared in Examples 1 to 4 and

Comparative Examples 1 to 5 was cut to a size of 5 cm * 5 cm and wetted for 2

hours under a PCT (pressure cooker test, 121 ^°C) condition. After keeping in a

lead bath of 288 °C for 10 seconds, the surface status was observed with eyes.

The sample in which delamination was observed was evaluated as X and the

one with no delamination was evaluated as O. c) Dielectric characteristics - Dielectric constant and dissipation factor

were measured at 1 MHz according to JIS C6481 , the Japanese standard for

copper clad laminate for high speed signal transfer, using an impedance analyzer. d) Adhesion to copper film (peel strength, kg/cm) - Each copper clad

laminate for high speed signal transfer prepared in Examples 1 to 4 and

Comparative Examples 1 to 5 was cut to a size of 10 cm x 1 cm. Adhesion

strength of the clad laminate to the copper film was measured at 0.8 mm/sec

using a UTM (universal testing machine).

[Table 1]

[Table 2]

As seen in Table 2, the thermoplastic resin compositions and the copper

clad laminate for high speed signal transfer of Examples 1 to 4, which had been

prepared according to the present invention, were superior in all of glass

transition temperature (T_g), heat resistance after moisture absorption, dielectric

constant, dissipation factor and adhesion to copper film to those of Comparatives

Example 1 to 5.

Especially, that of Comparative Example 1 , in which the fumed silica had not been used, and those of Comparative Example 2 and Comparative Example

3, in which a spherical silica and a planar silica had been used respectively

instead of the fumed silica, showed less heat resistance after moisture

absorption. And, that of Comparative Example 4, in which a phenol novolak

epoxy resin had been used instead of the dicyclopentadiene epoxy resin,

showed low dielectric constant, dissipation factor and heat resistance after

moisture absorption were poor. Also, that of Comparative Example 5, in which

15 phr of fumed silica and 150 phr of polyphenylene ether resin had been used,

showed poor heat resistance after moisture absorption and adhesion to copper

film.

As described above, the thermosetting resin of the present invention has

superior dielectric characteristics with low dielectric constant and dissipation

factor and is capable of significantly improving glass transition temperature, heat

it is useful for a copper clad laminate for multilayering and high speed signal

transfer.

Claims

WHAT IS CLAIMED IS:

1. A thermosetting resin composition for a high speed transmission

circuit board comprising: a) a cyanate ester based resin having at least two cyanate groups in one

2. The thermosetting resin composition of claim 1 , which comprises: a) 100 parts by weight of a cyanate ester based resin having at least two

the cyanate ester based resin and the dicyclopentadiene based epoxy resin.

3. The thermosetting resin composition of claim 1 , wherein a) the

cyanate ester based resin having at least two cyanate groups in one molecule is

a compound represented by the following Formula 1 :

where

CH, CF, I ³ CH, I ³ -c -c I — ³ I — — C— I H, CF, Rt is H CH,

each of R₂, R₃, R₄ and R₅ is hydrogen or CH₃, independently.

4. The thermosetting resin composition of claim 3, wherein a) the

cyanate ester based resin having at least two cyanate groups in one molecule is

at least one selected from the group consisting of 2,2-bis(4-

cyanatephenyl)propane, bis(3,5-dimethyl-4-cyanatephenyl)methane and 2,2- bis(4-cyanatephenyl)-1 ,1 ,1 ,3,3,3-hexafluoropropane.

5. The thermosetting resin composition of claim 1 , wherein b) the

dicyclopentadiene based epoxy resin is a compound represented by the

following Formula 2:

where n is 0 or a positive integer.

6. The thermosetting resin composition of claim 1 , wherein c) the fumed

silica has an average diameter ranging from 1 to 100 nm.

7. The thermosetting resin composition of claim 1 , wherein d) the

thermoplastic resin is at least one selected from the group consisting of

polystyrene, cyclic olefin copolymer, polyphenylene ether and polyphenylene

ether having an epoxy group.

8. The thermosetting resin composition of claim 1 , wherein e) the

cyanate ester resin curing accelerator is at least one selected from the group

consisting of iron naphthenate, copper naphthenate, zinc naphthenate, cobalt

naphthenate, iron octanoate, copper octanoate, zinc octanoate, cobalt octanoate,

lead acetylacetonate and cobalt acetylacetonate.

9. The thermosetting resin composition of claim 1 , wherein f) the epoxy

resin curing accelerator is at least one selected from the group consisting of 1- methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-

phenylimidazole, 2-cyclohexyl-4-methylimidazole, 4-butyl-5-ethylimidazole, 2-

methyl-5-ethylimidazole, 2-octyl-4-hexylimidazole and 2,5-chloro-4-

ethylimidazole.

10. The thermosetting resin composition of claim 1 , wherein g) the

primary phenolic compound is a compound represented by the following Formula

3:

where each of R₆ and R₇ is hydrogen or CH₃, independently; and n is 1 or 2.

11. The thermosetting resin composition of claim 10, wherein the

primary phenolic compound is at least one selected from the group consisting of

nonylphenol, dinonylphenol, octylphenol and 4-cumylphenol.

12. The thermosetting resin composition of claim 1 , wherein h) the flame

retardant is at least one selected from the group consisting of 1 ,2-dibromo-4-

(1 ,2-dibromoethyl)cyclohexane, tetrabromocyclohexane, hexabromocyclodecane

and 2,4,6-tris(tribromophenoxy)-1 ,3,5-triazine represented by the following

Formula 4:

13. A copper clad laminate for high speed signal transfer comprising the

thermosetting resin composition of claim 1.