U.S. patent application number 11/647598 was filed with the patent office on 2007-09-06 for resin composition excellent in dielectric properties, process for producing the same, varnish produced using the same, process for producing the varnish, and prepreg and metal-clad laminate using the resin composition and varnish.
Invention is credited to Daisuke Fujimoto, Yasuyuki Mizuno, Nozomu Takano, Kenichi Tomioka.
Application Number | 20070207326 11/647598 |
Document ID | / |
Family ID | 26587984 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070207326 |
Kind Code |
A1 |
Mizuno; Yasuyuki ; et
al. |
September 6, 2007 |
Resin composition excellent in dielectric properties, process for
producing the same, varnish produced using the same, process for
producing the varnish, and prepreg and metal-clad laminate using
the resin composition and varnish
Abstract
A resin composition comprising a cyanate compound (A) having 2
or more cyanato groups in the molecule; a phenol compound (B); a
silicone polymer (D) having at least one siloxane unit selected
from the group consisting of a tri-functional siloxane unit
represented by the formula RSiO.sub.3/2 and tetra-functional
siloxane unit represented by SiO.sub.4/2, polymerization degree of
7,000 or less, and at least one terminal functional group reactive
with hydroxyl group; and inorganic filler (E).
Inventors: |
Mizuno; Yasuyuki; (Ibaraki,
JP) ; Fujimoto; Daisuke; (Ibaraki, JP) ;
Tomioka; Kenichi; (Ibaraki, JP) ; Takano; Nozomu;
(Ibaraki-ken, JP) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Family ID: |
26587984 |
Appl. No.: |
11/647598 |
Filed: |
December 29, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10221171 |
Nov 15, 2002 |
7157506 |
|
|
PCT/JP01/02237 |
Mar 21, 2001 |
|
|
|
11647598 |
Dec 29, 2006 |
|
|
|
Current U.S.
Class: |
428/447 ;
523/209; 524/404; 524/413; 524/424; 524/436; 524/437; 524/445;
524/588 |
Current CPC
Class: |
Y10T 428/31663 20150401;
B32B 2311/12 20130101; C08L 79/04 20130101; B32B 15/14 20130101;
C08G 73/0655 20130101; C08L 79/04 20130101; C08K 5/13 20130101;
B32B 27/18 20130101; C08K 5/315 20130101; C08L 83/04 20130101; C08L
2666/02 20130101; H05K 1/0353 20130101; C08K 5/5419 20130101 |
Class at
Publication: |
428/447 ;
523/209; 524/404; 524/413; 524/424; 524/436; 524/437; 524/445;
524/588 |
International
Class: |
B32B 15/08 20060101
B32B015/08; C08K 9/06 20060101 C08K009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2000 |
JP |
P2000-78792 |
Mar 21, 2000 |
JP |
P2000-78796 |
Claims
1. (canceled)
2. A varnish comprising a resin composition including a cyanate
compound (A) having 2 or more cyanato groups in the molecule; a
phenol compound (B); a polyphenylene ether resin (C); a silicone
polymer (D) having at least one siloxane unit selected from the
group consisting of a tri-functional siloxane unit represented by
the formula RSiO.sub.3/2 (wherein, R is an organic group, and when
2 or more Rs are present in the silicone polymer, they may be the
same or different) and tetra-functional siloxane unit represented
by Si0.sub.4/2, polymerization degree of 7,000 or less and at least
one terminal functional group reactive with hydroxyl group; and
inorganic filler (E), treated with said silicone polymer (D),
dissolved or dispersed in a solvent, wherein the non-volatile
content of the varnish is 54% by weight or more.
3. The varnish according to claim 2, wherein the equivalent ratio
of said phenol compound (B) to cyanate compound (A) is 0.025 to
0.30 as the ratio of the phenolic hydroxylic group in said phenol
compound (B) to cyanato group in said cyanate compound (A)
(hydroxylic group/cyanato group ratio); said polyphenylene ether
resin (C) is incorporated at 1 to 300 parts by weight per 100 parts
by weight of said cyanate compound (A); said silicone polymer (D)
is incorporated at 0.01 to 20% by weight on said inorganic filler
(E); and said inorganic filler (E) is incorporated at 1 to 1,000
parts by weight per 100 parts by weight of total of said cyanate
compound (A), phenol compound (B) and polyphenylene ether resin
(C).
4. A varnish comprising a resin composition including a cyanate
compound (A) having 2 or more cyanato groups in the molecule; a
phenol compound (B); a polyphenylene ether resin (C); and an
inorganic filler (F) surface-treated with a silicone polymer (D)
having at least one siloxane unit selected from the group
consisting of a tri-functional siloxane unit represented by the
formula RSiO.sub.3/2 (wherein, R is an organic group, and when 2 or
more Rs are present in the silicone polymer, they may be the same
or different) and tetra-functional siloxane unit represented by
Si0.sub.4/2, polymerization degree of 7,000 or less and at least
one terminal functional group reactive with hydroxyl group,
dissolved or dispersed in a solvent, wherein the non-volatile
content of the varnish is 54% by weight or more.
5. The varnish according to claim 4, wherein the equivalent ratio
of said phenol compound (B) to cyanate compound (A) is 0.025 to
0.30 as the ratio of the phenolic hydroxylic group in said phenol
compound (B) to the cyanato group in said cyanate compound (A)
(hydroxylic group/cyanato group ratio); said polyphenylene ether
resin (C) is incorporated at 1 to 300 parts by weight per 100 parts
by weight of said cyanate compound (A); and said inorganic filler
(F) is incorporated at 1 to 1,000 parts by weight per 100 parts by
weight of total of said cyanate compound (A), phenol compound (B)
and polyphenylene ether resin (C).
6. A varnish comprising a resin composition including a
phenol-modified cyanate ester oligomer produced by reacting a
cyanate compound (A) having 2 or more cyanato groups in the
molecule with a phenol compound (B) at an equivalent ratio of the
phenolic hydroxylic group in the phenol compound (B) to the cyanato
group in the cyanate compound (A) (hydroxylic group/cyanato group
ratio) in a range from 0.01 to 0.30; phenol compound (B)
incorporated at a hydroxylic group/cyanato group equivalent ratio
in a range below 0.29 (this equivalent ratio is in a range from
0.025 to 0.30, with this phenol compound (B) combined with the
phenol compound (B) used for production of the phenol-modified
cyanate ester oligomer); polyphenylene ether resin (C); and
inorganic filler (F) surface-treated with a silicone polymer (D)
having at least one siloxane unit selected from the group
consisting of a tri-functional siloxane unit represented by the
formula RSiO.sub.3/2 (wherein, R is an organic group, and when 2 or
more Rs are present in the silicone polymer, they may be the same
or different) and tetra-functional siloxane unit represented by
SiO.sub.4/2, polymerization degree of 7,000 or less, and at least
terminal functional group reactive with hydroxyl group, dissolved
or dispersed in a solvent, wherein the non-volatile content of the
varnish is 54% by weight or more.
7. The varnish according to claim 6, wherein said polyphenylene
ether resin (C) is incorporated at 1 to 300 parts by weight per 100
parts by weight of said cyanate compound (A); and said inorganic
filler (F) is incorporated at 1 to 1,000 parts by weight per 100
parts by weight of total of said cyanate compound (A), phenol
compound (B) and polyphenylene ether resin (C).
8. A varnish comprising a resin composition including a
phenol-modified cyanate ester oligomer containing a polyphenylene
ether resin, produced by reacting a cyanate compound (A) with a
phenol compound (B) in the presence of a polyphenylene ether resin
(C) at an equivalent ratio of the phenolic hydroxylic group in the
phenol compound (B) to the cyanato group in the cyanate compound
(A) (hydroxylic group/cyanato group ratio) in a range from 0.01 to
0.30; phenol compound (B) incorporated at an equivalent ratio of
the phenolic hydroxylic group in the phenol compound (B) to the
cyanato group in the cyanate compound (A) (hydroxylic group/cyanato
group ratio) in a range below 0.29 (this equivalent ratio is in a
range from 0.025 to 0.30, with this phenol compound (B) combined
with the phenol compound (B) used for production of the
phenol-modified cyanate ester oligomer); and inorganic filler (F)
surface-treated with a silicone polymer (D) having at least one
siloxane unit selected from the group consisting of a
tri-functional siloxane unit represented by the formula
RSiO.sub.3/2 (wherein, R is an organic group, and when 2 or more Rs
are present in the silicone polymer, they may be the same or
different) and tetra-functional siloxane unit represented by
SiO.sub.4/2, polymerization degree of 7,000 or less, and at least
one terminal functional group reactive with hydroxyl group,
dissolved or dispersed in a solvent, wherein the non-volatile
content of the varnish is 54% by weight or more.
9. The varnish according to claim 8, wherein said polyphenylene
ether resin (C) is incorporated at 1 to 300 parts by weight per 100
parts by weight of said cyanate compound (A); and said inorganic
filler (F) is incorporated at 1 to 1,000 parts by weight per 100
parts by weight of total of said cyanate compound (A), phenol
compound (B) and polyphenylene ether resin (C).
10. The varnish according to claim 6, wherein said cyanate compound
(A) is reacted to have a conversion of 10 to 70% by mol to produce
said phenol-modified cyanate ester oligomer, or phenol-modified
cyanate ester oligomer containing a polyphenylene ether resin.
11. The varnish according to claim 2, wherein said cyanate compound
(A) is at least one compound selected from those represented by the
following formula (Ia): ##STR12## (wherein, R.sub.1 is an alkylene
group of 1 to 3 carbon atoms, which may be substituted by a halogen
atom, or represented by the general formula (II) or (III); R.sub.2
and R.sub.3 are each hydrogen atom on an alkyl group of 1 to 4
carbon atoms, and may be the same or different; and R.sub.4 is an
alkylene group of 1 to 3 carbon atoms): ##STR13##
12. The varnish according to claim 11, wherein said cyanate
compound having 2 or more cyanato groups in the molecule
represented by the formula (I) is selected from the group
consisting of 2,2-bis(4-cyanatophenyl)propane,
bis(4-cyanatophenyl)ethane,
bis(3,5-dimethyl-4-cyanatophenyl)methane,
2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane,
.alpha.,.alpha.'-bis(4-cyanatophenyl)-m-diisopropylbenzene, and
cyanate-esterified phenol-added dicyclopentadiene polymer.
13. The varnish according to claim 2, wherein said phenol compound
(B) is at least one selected from the compounds represented by the
following formula (IV) or (Va): ##STR14## (wherein, R.sub.5 and
R.sub.6 are each hydrogen atom or methyl group, and may be the same
or different; and "m" is an integer of 1 to 3) ##STR15## (wherein,
R.sub.7 is hydrogen atom or methyl group; R.sub.8 is methyl, ethyl
or 2,2-dimethylpropyl; and "n" is an integer of 1 to 2).
14. The varnish according to claim 13, wherein said phenol compound
represented by the formula (IV) is at least one compound selected
from the group consisting of p-(.alpha.-cumyl)phenol, and mono-,
di- and tri-.alpha.-methylbenzyl)phenol.
15. The varnish according to claim 13, wherein said phenol compound
represented by the formula (Va) is at least one compound selected
from the group consisting of p-tert-butylphenol, 2,4- or
2,6-di-tert-butylphenol, p-tert-aminophenol and
p-tert-octylphenol.
16. The varnish according to claim 2, wherein said polyphenylene
ether resin (C) is an alloyed polymer of
poly(2,6-dimethyl-1,4-phenylene) ether and polystyrene, or alloyed
polymer of poly(2,6-dimethyl-1,4-phenylene) ether and
styrene/butadiene copolymer which contains the
poly(2,6-dimethyl-1,4-phenylene) ether at 50% or more.
17. The varnish according to claim 2, wherein said silicone polymer
(D) is composed of the tri-functional siloxane unit represented by
the formula RSiO.sub.3/2, and has a polymerization degree of 2 to
7,000.
18. The varnish according to claim 2, wherein said silicone polymer
(D) is composed of the tetra-functional siloxane unit represented
by the formula Si0.sub.4/2 and has a polymerization degree of 7,000
or less.
19. The varnish according to claim 2, wherein said silicone polymer
(D) is composed of a bi-functional siloxane unit represented by the
formula R.sub.2SiO.sub.2/2 (wherein, R.sub.2 is the same as R) and
the tetra-functional siloxane unit, and has a polymerization degree
of 7,000 or less.
20. The varnish according to claim 2, wherein said silicone polymer
(D) is composed of the tri- and tetra-functional siloxane unit, and
has a polymerization degree of 7,000 or less.
21. The varnish according to claim 2, wherein said silicone polymer
(D) is composed of the bi-functional siloxane unit represented by
the formula R.sub.2SiO.sub.2/2 (wherein, R.sub.2 is the same as R)
and the tri-functional siloxane unit, and has a polymerization
degree of 7,000 or less.
22. The varnish according to claim 2, wherein said silicone polymer
(D) is composed of the bi-functional siloxane unit represented by
the formula R.sub.2SiO.sub.2/2 (wherein, R.sub.2 is the same as R)
and tri- and tetra-functional siloxane unit, and has a
polymerization degree of 7,000 or less.
23. The varnish according to claim 2, wherein the tetra-functional
siloxane unit accounts for 15% by mol or more of the total siloxane
units.
24. The varnish according to claim 2, wherein the tri-functional
siloxane unit accounts for 15% by mol or more of the total siloxane
units.
25. The varnish according to claim 2, wherein said inorganic filler
(E) is at least one selected from the group consisting of alumina,
titanium oxide, mica, silica, beryllia, barium titanate, potassium
titanate, strontium titanate, calcium titanate, aluminum carbonate,
aluminum hydroxide, aluminum silicate, calcium carbonate, calcium
silicate, magnesium silicate, silicon nitride, boron nitride, clay,
talc, aluminum borate, and silicon carbide.
26. The varnish according to claim 4, wherein said inorganic filler
(F) is surface-treated with a coupling agent together with the
silicone polymer (D).
27. The varnish according to claim 26, wherein said coupling agent
is a silane-based one.
28. The varnish according to claim 26, wherein said coupling agent
is a titanate-based one.
29. The varnish according to claim 2, wherein a flame-retardant (G)
is incorporated as a component.
30. The varnish according to claim 29, wherein said flame-retardant
(G) has no reactivity with said cyanate compound (A).
31. The varnish according to claim 29, wherein said flame-retardant
(G) is at least one alicyclic one selected from the group
consisting of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane,
tetrabromocyclooctane and hexabromocyclododecane.
32. The varnish according to claim 29, wherein said flame-retardant
(G) is at least one selected from the group consisting of
bis(tribromophenoxy)ethane, a brominated triphenylcyanurate
represented by the formula (VI), brominated polyphenylene ether
represented by the formula (VII) and brominated polystyrene
represented by the formula (VIII): ##STR16## (wherein, "l," "m,"
and "n" are each an integer of 1 to 5) ##STR17## (wherein, "n" is
an integer) ##STR18## (wherein, "m" is an integer of 1 to 5, and
"n" is an integer).
33. The varnish according to claim 2, further including an epoxy
resin (H) having two or more glycidyl in the molecule.
34. The varnish according to claim 33, wherein said epoxy resin (H)
is at least one selected from the group consisting of bisphenol A
type epoxy resin, brominated bisphenol A type epoxy resin, phenol
novolac type epoxy resin, cresol novolac type epoxy resin,
bisphenol A novolac type epoxy resin, biphenyl type epoxy resin,
epoxy resin having a naphthalene structure, epoxy resin having an
aralkyl structure, epoxy resin represented by the formula (IX) and
epoxy resin having a cyclopentadiene structure, represented by the
formula (X): ##STR19## (wherein, R.sub.9 is hydrogen atom or an
alkyl group of 1 to 4 carbon atoms; R.sub.10 is an alkyl group of 1
to 4 carbon atoms; and "n" is an average of 1 to 7) ##STR20##
(wherein, "n" is an integer).
35. The varnish according to claim 2, wherein an antioxidant (I)
selected from the group consisting of a phenol-based one and
organosulfur-based one is incorporated as a component.
36. The varnish according to claim 35, wherein said phenol-based
antioxidant (I) is a bisphenol-based one.
37. A process for producing a varnish, wherein the cyanate compound
(A) or the phenol-modified cyanate ester oligomer according to
claim 6 and phenol compound (B) are incorporated in a treatment
solution containing the silicone polymer (D) and inorganic filler
(E), in which the inorganic filler (E) is surface-treated, and
wherein the non-volatile content of the varnish is 54% by weight or
more.
38. A process for producing a varnish, wherein the cyanate compound
(A) or phenol-modified cyanate ester oligomer according to claim 6
and phenol compound (B) are dissolved or dispersed in the solvent,
and the resultant solution or dispersion is incorporated with the
inorganic filler (F) surface-treated with the silicone polymer (D)
or a treatment solution containing the inorganic filler (F) in
which the inorganic filler (F) is surface-treated with the silicone
polymer (D), wherein the non-volatile content of the varnish is 54%
by weight or more.
39. A process for producing a varnish, comprising: surface treating
inorganic filler (E) in a treatment solution containing silicone
polymer (D), and incorporating resultant treatment solution
containing the inorganic filler with (1) cyanate compound (A) or a
phenol-modified cyanate oligomer produced by reacting the cyanate
compound (A) with phenol compound (B), and phenol compound (B) and
polyphenylene ether resin (C), or (2) phenol-modified cyanate
oligomer containing polyphenylene ether resin produced by reacting
the cyanate compound (A) with the phenol compound (B) in the
presence of the polyphenylene ether resin (C), and phenol compound
(B), wherein the non-volatile content of the varnish is 54% by
weight or more.
40. A process for producing a varnish, wherein (1) cyanate compound
(A) or a phenol-modified cyanate oligomer produced by reacting the
cyanate compound (A) with the phenol compound (B), and phenol
compound (B) and polyphenylene ether resin (C), or (2)
phenol-modified cyanate oligomer containing polyphenylene ether
resin produced by reacting the cyanate compound (A) with the phenol
compound (B) in the presence of the polyphenylene ether resin (C)
are dissolved or dispersed in a solvent, and resultant solution or
dispersion is incorporated with inorganic filler (F)
surface-treated with silicone polymer (D) or a treatment solution
containing the inorganic filler (F) in which the inorganic filler
(F) is surface-treated with the silicone polymer (D), wherein the
non-volatile content of the varnish is 54% by weight or more.
41. The process for producing a varnish according to claim 40,
wherein said phenol-modified cyanate oligomer containing the
polyphenylene ether resin is produced by reacting the cyanate
compound (A) with the phenol compound (B) in the presence of the
polyphenylene ether resin (C) in the solution or dispersion in
which the polyphenylene ether resin (C) is dissolved or dispersed
beforehand at an equivalent ratio of the phenolic hydroxylic group
in the phenol compound (B) to the cyanato group in the cyanate
compound (A) (hydroxylic group/cyanato group ratio) in a range from
0.01 to 0.30.
42. A process for producing a varnish, wherein the varnish produced
by the process according to claim 37 is further incorporated with
flame-retardant (G), epoxy resin (H) and/or antioxidant (I).
43. A prepreg which is obtainable by impregnating a base material
with the varnish according to claim 2, and then drying the same at
80 to 200.degree. C.
44. A metal-clad laminate comprising one or more sheets of the
prepreg according to claim 43, placed one on another to produce the
laminate when two or more sheets are used, wherein the sheet or
laminate is coated with a metal-clad at least on one side and
heated under pressure.
45. The varnish according to claim 25, wherein said inorganic
filler (E) is clay, and the clay is fired clay.
46. The varnish according to claim 2, wherein said solvent is at
least one selected from the group consisting of alcohols, ketones,
aromatic hydrocarbons, esters and amides.
47. The varnish according to claim 2, wherein the phenol compound
(B) is a monovalent phenol compound.
48. The varnish according to claim 6, wherein said phenol-modified
cyanate ester includes triazine rings containing a component
derived from the phenol compound (B).
49. The varnish according to claim 48, wherein a number of cyanato
groups extending from a respective triazine ring is 1 or 2.
50. The varnish according to claim 6, wherein the phenol compound
(B) is a monovalent phenol compound.
51. An article of manufacture comprising a plurality of prepregs,
at least one of said plurality of prepregs being formed by a
process of impregnating a base material for a prepreg with the
varnish of claim 2, to form an impregnated base material, and
drying the impregnated base material, the plurality of prepregs
being laminated to each other to form a laminate of prepregs.
52. The article of manufacture according to claim 51, further
comprising a metal layer on the laminate of prepregs, thereby
forming a metal-clad laminate.
53. The article of manufacture according to claim 52, wherein the
metal layer is a wiring layer, and the article of manufacture is a
printed wiring board.
54. An article of manufacture comprising a plurality of prepregs,
at least one of said plurality of prepregs being formed by a
process of impregnating a base material for a prepreg with the
varnish of claim 4, to form an impregnated base material, and
drying the impregnated base material, the plurality of prepregs
being laminated to each other to form a laminate of prepregs.
55. The article of manufacture according to claim 54, further
comprising a metal layer on the laminate of prepregs, thereby
forming a metal-clad laminate.
56. The article of manufacture according to claim 55, wherein the
metal layer is a wiring layer, and the article of manufacture is a
printed wiring board.
57. The varnish according to claim 2, wherein the non-volatile
content of the varnish is 63% by weight or less.
58. The varnish according to claim 4, wherein the non-volatile
content of the varnish is 63% by weight or less.
59. The varnish according to claim 6, wherein the non-volatile
content of the varnish is 63% by weight or less.
60. The varnish according to claim 8, wherein the non-volatile
content of the varnish is 63% by weight or less.
61. The process according to claim 37, wherein the non-volatile
content of the varnish is 63% by weight or less.
62. The process according to claim 38, wherein the non-volatile
content of the varnish is 63% by weight or less.
63. The process according to claim 39, wherein the non-volatile
content of the varnish is 63% by weight or less.
64. The process according to claim 40, wherein the non-volatile
content of the varnish is 63% by weight or less.
Description
[0001] This application is a Continuation application of
application Ser. No. 10/221,171, filed Nov. 15, 2002, which is an
application filed under 35 U.S.C. .sctn.371 of International (PCT)
Application No. PCT/JP01/02237 filed Mar. 21, 2001.
TECHNICAL FIELD
[0002] The present invention relates to a resin composition
suitable for printed-wiring boards for various purposes, e.g.,
parts for filters to be built in terminal devices for wireless
communications which are required to show a low loss of signal in a
high-frequency bandwidth, antennas at wireless base stations and
high-speed computers including microprocessors which work at an
operating frequency exceeding several hundreds MHz; varnish,
prepreg and metallic copper clad laminate produced using the resin
composition; and process for producing the resin composition.
BACKGROUND ART
[0003] Recently, electronic devices for movable communications are
required to process a large volume of information at a high speed,
and electrical signals which they handle are increasing in
frequency. However, intensity of a signal tends to decay faster as
its frequency increases. Therefore, the printed-wiring boards in
this field need board materials of low transmission loss. In other
words, it is necessary to use resin materials of low relative
dielectric constant and dielectric loss tangent in a high frequency
bandwidth for these boards.
[0004] For electronic devices, e.g., computers, high-speed
microprocessors working at an operating frequency exceeding 500 MHz
have been developed and signal frequency has been increasing, in
order to allow them to treat a larger volume of information in a
shorter time. One of the problems which have come to the fore in
those devices handling high-speed pulse signals is delay on the
printed-wiring board. Signal delay time on a printed-wiring board
increases in proportion to the square root of relative dielectric
constant of the insulator around the wiring. Therefore, the wiring
boards for computers or the like need resins of lower relative
dielectric constant as the board materials.
[0005] The related industries have been using thermoplastic resin
materials of low relative dielectric constant and dielectric loss
tangent, e.g., fluorine-based ones, to cope with the increased
signal frequency. These materials, however, tend to lack fluidity
resulting from their high melt viscosity, which causes problems,
e.g., need for high temperature and pressure for pressing, and
insufficient dimensional stability and adhesion to plated metals.
Several proposals have been made to solve these problems, e.g., use
of a composition comprising epoxy-based resin and cyanate ester
which is known as one of the resins of lowest relative dielectric
constant and dielectric loss tangent among thermosetting resins
(Japanese Patent Publication No. 46-41112) as a composition of
cyanate ester, and a composition comprising bismaleimide, cyanate
ester and epoxy-based resin (Japanese Patent Publication No.
52-31279).
[0006] Use of thermoplastic resins is also proposed to improve the
high-frequency characteristics. These resins include resin
compositions based on a polyphenylene ether (PPO or PPE), which
shows good dielectric properties among heat-resistant,
thermoplastic resins, e.g., a resin composition comprising a
polyphenylene ether, crosslinkable polymer and monomer (Japanese
Patent Publication No. 5-77705), and another one comprising a
polyphenylene ether having a specific settable functional group and
crosslinkable monomer (Japanese Patent Publication No.
6-92533).
[0007] The other resin compositions proposed to improve the
high-frequency characteristics include those comprising a cyanate
ester resin and polyphenylene ether having good dielectric
properties, e.g., a composition comprising a cyanate ester,
bismaleimide and polyphenylene ether (Japanese Patent Laid-open
Publication No. 63-33506), and another one comprising a product by
the reaction between a phenol-modified resin and cyanate ester, and
polyphenylene ether (Japanese Patent Laid-open Publication No.
5-311071). Another resin composition as a heat-resistant forming
material of good dielectric properties is comprising a
polyphenylene ether and cyanate ester resin kneaded with each other
(Japanese Patent Publication No. 61-18937).
[0008] On the other hand, printed-wiring boards, not limited to
those for signals of higher frequency, have been becoming more and
more densified by increasing number of layers for the laminate,
making the laminate thinner, and decreasing through-hole size and
pitch as electronic devices becoming more compact and more
functional. Therefore, the laminate is increasingly required to
have higher heat resistance, drill-machinability and insulation
characteristics, among others. The methods which have been widely
used to improve heat resistance and insulation characteristics of
the resins include increasing their glass transition temperature
(Tg) to improve the properties of their set products. However,
improvement of the resin alone is insufficient to fully satisfy the
above characteristics.
[0009] One of the methods to solve these problems is use of an
inorganic filler as one component for the resin composition.
Inorganic fillers have been studied not only as a bulking agent but
also as an agent for improving properties of the composition, e.g.,
dimensional stability and resistance to moisture and heat. More
recently, use of a special filler has been studied to provide the
composition with excellent functions, e.g., high dielectric
constant, low dielectric loss tangent, high heat radiation and high
strength.
[0010] Under these circumstances, incorporation of an inorganic
filler is proposed also for resin materials which can handle
high-frequency signals to improve their properties, e.g., heat
resistance and dimensional stability. Some of the
filler-incorporated resin compositions proposed so far include
those comprising a cyanate ester and bismaleimide, and cyanate
ester, bismaleimide and epoxy-based resin (Japanese Patent
Publication No. 63-33505); polyphenylene ether and crosslinkable
monomer (Japanese Patent Laid-open Publication Nos. 62-275744 and
4-91160); and phenol-modified polyphenylene ether and epoxy resin
(Japanese Patent Publication No. 10-212336).
[0011] However, the method disclosed by Japanese Patent Publication
No. 46-41112 or 52-31279, although giving a resin composition of
slightly decreased relative dielectric constant, involves a problem
of insufficient high-frequency characteristics of the composition,
resulting from incorporation of a thermosetting resin other than a
cyanate ester resin.
[0012] The method disclosed by Japanese Patent Publication No.
5-77705 or 6-92533, although giving a resin composition of improved
dielectric properties, involves a problem of high melt viscosity
and hence insufficient fluidity of the composition, resulting from
polyphenylene ether as the major component, which is inherently
thermoplastic polymer. The resin composition, therefore, is
unsuitable for laminates because it needs high temperature and
pressure in the pressing step, and also unsuitable for
multi-layered printed-wiring boards which are treated to fill the
groove between fine circuit patterns because of its insufficient
formability.
[0013] The method disclosed by Japanese Patent Publication No.
63-33506 or 5-311071, although giving a resin composition of
slightly improved dielectric properties, involves a problem of
still insufficient high-frequency characteristics of the
composition, resulting from the thermosetting resin used in
combination with the polyphenylene ether, because it is a product
of the reaction between the bismaleimide and cyanate ester resin,
or between the phenol-modified resin and cyanate ester, and brings
the adverse effect(s) of the component other than the cyanate
ester. Increasing the polyphenylene ether content to improve
high-frequency characteristics of the composition may cause a
problem of deteriorated formability resulting from high melt
viscosity and hence insufficient fluidity of the composition, as is
the case with the above-described polyphenylene ether-based
one.
[0014] The resin composition comprising a polyphenylene ether and
cyanate ester resin kneaded with each other (Japanese Patent
Publication No. 61-18937), although having good dielectric
properties and relatively good formability, because of decreased
melt viscosity resulting from modification with the cyanate ester
resin, tends to have the dielectric properties of high relative
dielectric constant for its low dielectric loss tangent, when the
cyanate ester is separately incorporated as a setting component,
with the result that transmission loss may not be sufficiently
reduced in a GHz bandwidth. Moreover, decreasing the cyanate ester
content to decrease dielectric loss tangent of the composition,
which is accompanied by increased polyphenylene ether, may cause a
problem of deteriorated formability resulting from high melt
viscosity and hence insufficient fluidity of the composition, as is
the case with the above-described polyphenylene ether-based
one.
[0015] In the method which incorporates an inorganic filler in a
resin composition to make the laminate of the composition more
functional (Japanese Patent Publication No. 63-33505), the filler
selected from the common ones begins to settle gradually when
incorporated in a varnish. It is therefore necessary to disperse
the filler by an adequate procedure, e.g., stirring the composition
again, before it is spread. However, it may not be sufficiently
dispersed by stirring alone, when it settles massively to
agglomerate. The filler may cause other problems in the prepreg
production step; it will settle in a portion in a varnish tank or
impregnation tank where varnish tends to accumulate, and also will
be gradually deposited on a roll or the like, to decrease
spreadability (workability) of the composition, significantly
deteriorating outer appearances of the prepreg and preventing
uniform dispersion of the filler, and hence deteriorating
properties of the laminate of the composition, e.g., adhesion at
the interface, resistance to moisture, drill-machinability and
insulation characteristics.
[0016] One of the methods to improve dispersibility of the filler
is coating the filler particles beforehand with a coupling agent or
the like. However, the surface treatment increases the filler cost
and greatly limits types of the commercial available products, and
it is difficult to select the treated filler suitable for a variety
of resin composition production systems. On the other hand,
quantity of a filler incorporated in resin materials tends to
increase, for improving their functions more, which is accompanied
by significantly increased quantity of the filler settling in a
system and deposited on a roll or the like. Therefore, the filler
has been increasingly required to be more dispersible and
thixotropic. The conventional treatment with a coupling agent is
difficult to satisfy these characteristics.
[0017] When a filler is to be surface-treated, it is normally dried
under heating after being treated, e.g., by being immersed in, or
sprayed with, a diluted solution of the treatment agent. The drying
step involves two types of problems, oligomerization of the
coupling agent on the treated filler surface to form a physically
adsorbed layer, and agglomeration of the filler particles, which
requires finely crushing the agglomerates before the filler is
incorporated in a varnish, which, in turn, causes a problem of
leaving an unevenly treated layer on the filler surface. The
physically adsorbed layer and unevenly treated layer, when formed,
deteriorate adhesion of the resultant laminate at the interface
between the filler and resin.
[0018] One method directly adds a coupling agent while a varnish is
being incorporated (Japanese Patent Laid-open Publication No.
61-272243). The varnish used in this method is viscous, because the
resin is incorporated beforehand. Therefore, it can avoid
agglomeration of the filler particles to some extent, but is
difficult to selectively direct the coupling agent evenly onto the
filler particle surfaces, causing problems of insufficient adhesion
at the interface between the inorganic filler and resin, and
insufficient dispersibility of the filler in the resin.
[0019] Particularly, incorporation of an inorganic filler in the
polyphenylene ether-based resin material, disclosed in Japanese
Patent Laid-open Publication No. 62-275744, 4-91160 or 10-212336,
involves a problem of very high viscosity of the molten
polyphenylene ether and of the solution of the ether dissolved in a
solvent, making it difficult to evenly disperse the filler in the
resin. This significantly agglomerates the filler particles,
producing the defects, e.g., voids, at the interface between the
inorganic filler and resin, and deteriorates properties of the set
product and laminate of the composition, e.g., resistance to
moisture, drill-machinability and insulation characteristics.
[0020] Surface treatment of an inorganic filler on a commercial
scale is completed in a very short time, even when the filler is
treated with a common, commercial coupling agent. As a result, the
filler particles are surface-treated insufficiently, because they
are covered only with a rigid, thin layer unevenly. Moreover, the
physically adsorbed layer tends to be eluted out into the resin
layer, and elution of the adsorbed layer, when occurs, is likely to
cause problems, e.g., unevenly set resin in the vicinity of the
interface, and adhesion to the interface between the filler and
resin, resulting from reduced strength. As discussed above, it is
difficult to disperse an inorganic filler in a highly viscous
polymer, e.g., polyphenylene ether, without agglomerating the
filler particles. Therefore, incorporation of an inorganic filler
in the resin has caused problems of deteriorated properties of the
laminate of the resultant composition, e.g., resistance to
moisture, drill-machinability and insulation characteristics, as
discussed above. Moreover, a resin material based on a
thermoplastic resin, e.g., polyphenylene ether, involves a problem
of insufficient dimensional stability and adhesion to plated
metals.
[0021] The present invention has been developed under these
situations. It is an object of the present invention to provide a
resin composition exhibiting excellent dielectric properties in a
high-frequency bandwidth, as formable and machinable as a laminate
of the conventional thermosetting resin, e.g., epoxy resin, and
capable of giving laminates and printed-wiring boards of high heat
resistance and excellent reliability of electrical insulation. It
is another object of the present invention to provide a process for
producing a varnish, prepreg and metal-clad laminate using the
above resin composition, and the resin composition itself.
DISCLOSURE OF THE INVENTION
[0022] The inventors of the present invention have found, after
extensive study to solve the above problems, that the object of the
present invention can be achieved by use of a resin composition
comprising: a cyanate ester compound; phenol compound; and
inorganic filler treated with a silicone polymer which has a
functional group reactive with surface hydroxylic group by its
structure or after absorbing moisture.
[0023] They have also found that the object of the present
invention can be achieved by use of the above resin composition
incorporated with a polyphenylene ether resin.
[0024] They have also found that the object of the present
invention can be achieved by use of the above resin composition
incorporated with a phenol-modified cyanate ester oligomer
composition, as the product of the reaction between a cyanate ester
compound and phenol compound, in place of the above-described
cyanate ester compound.
[0025] The present invention is a resin composition comprising, as
its essential components: a cyanate compound (A) having 2 or more
cyanato groups in the molecule; a phenol compound (B); a silicone
polymer (D) having at least one siloxane unit selected from the
group consisting of a tri-functional siloxane unit represented by
the formula RSiO.sub.3/2 (wherein, R is an organic group, and when
2 or more Rs are present in the silicone polymer, they may be the
same or different) and tetra-functional siloxane unit represented
by SiO.sub.4/2, polymerization degree of 7,000 or less, and at
least one terminal functional group reactive with hydroxyl group;
and an inorganic filler (E).
[0026] The present invention is a resin composition comprising: a
cyanate compound (A) having 2 or more cyanato groups in the
molecule; phenol resin (B); and inorganic filler (F)
surface-treated with a silicone polymer having at least one
siloxane unit selected from the group consisting of a
tri-functional siloxane unit represented by the formula
RSiO.sub.3/2 (wherein, R is an organic group, and when 2 or more Rs
are present in the silicone polymer, they may be the same or
different) and tetra-functional siloxane unit represented by
SiO.sub.4/2, polymerization degree of 7,000 or less, and at least
one terminal functional group reactive with hydroxyl group.
[0027] The present invention is a resin composition comprising: a
phenol-modified cyanate ester oligomer produced by reacting a
cyanate compound (A) having 2 or more cyanato groups in the
molecule with a phenol compound (B) at an equivalent ratio of the
phenolic hydroxylic group in the phenol compound (B) to the cyanato
group in the cyanate compound (A) (hydroxylic group/cyanato group
ratio) in a range from 0.01 to 0.30; the phenol compound (B)
incorporated at an equivalent ratio of the phenolic hydroxylic
group in the phenol compound (B) to the cyanato group in the
cyanate compound (A) (hydroxylic group/cyanato group ratio) in a
range below 0.29 (this equivalent ratio is in a range from 0.025 to
0.30, with this phenol compound (B) combined with the phenol
compound (B) used for production of the phenol-modified cyanate
ester oligomer); and an inorganic filler (F) surface-treated with a
silicone polymer (D) having at least one siloxane unit selected
from the group consisting of a tri-functional siloxane unit
represented by the formula RSiO.sub.3/2 (wherein, R is an organic
group, and when 2 or more Rs are present in the silicone polymer,
they may be the same or different) and tetra-functional siloxane
unit represented by SiO.sub.4/2, polymerization degree of 7,000 or
less, and at least one terminal functional group reactive with the
hydroxyl group.
[0028] The present invention is the above resin composition which
further contains a polyphenylene ether resin (C).
[0029] The present invention is a resin composition comprising: a
phenol-modified cyanate ester oligomer containing a polyphenylene
ether resin, produced by reacting a cyanate compound (A) with a
phenol compound (B) in the presence of a polyphenylene ether resin
(C) at an equivalent ratio of the phenolic hydroxylic group in the
phenol compound (B) to the cyanato group in the cyanate compound
(A) (hydroxylic group/cyanato group ratio) in a range from 0.01 to
0.30; the phenol compound (B) incorporated at an equivalent ratio
of the phenolic hydroxylic group in the phenol compound (B) to the
cyanato group in the cyanate compound (A) (hydroxylic group/cyanato
group ratio) in a range below 0.29 (this equivalent ratio is in a
range from 0.025 to 0.30, with this phenol compound (B) combined
with the phenol compound (B) used for production of the
phenol-modified cyanate ester oligomer); and an inorganic filler
(F) surface-treated with a silicone polymer (D) having at least one
siloxane unit selected from the group consisting of a
tri-functional siloxane unit represented by the formula.
RSiO.sub.3/2 (wherein, R is an organic group, and when 2 or more Rs
are present in the silicone polymer, they may be the same or
different) and tetra-functional siloxane unit represented by
SiO.sub.4/2, polymerization degree of 7,000 or less, and at least
one terminal functional group reactive with the hydroxyl group.
[0030] The present invention is a process for producing a
phenol-modified cyanate ester oligomer by reacting a cyanate
compound (A) having 2 or more cyanato groups in the molecule with a
phenol compound (B) represented by the general formula (I) at an
equivalent ratio of the phenolic hydroxylic group in the phenol
compound (B) represented by the general formula (I) to the cyanato
group in the cyanate compound (A) having 2 or more cyanato groups
in the molecule (hydroxylic group/cyanato group ratio) in a range
from 0.025 to 0.30.
[0031] The present invention is a resin varnish produced by
dissolving or dispersing one of the above resin composition in a
solvent.
[0032] The present invention is a metal-clad laminate produced by
drying a base material impregnated with one of the above resin
compositions or resin varnish to produce the prepreg, placing the
two or more prepreg sheets one on another to produce the laminate,
and heating and pressing the laminate after it is coated with a
metallic foil on at least one of the external sides.
[0033] The resin composition, varnish and prepreg provided by the
present invention are excellent in dispersibility of the inorganic
filler in the resin material and also in adhesion at the interface
between the inorganic filler and resin material, high in
dimensional stability, good in workability when they are spread on
an object, and also good in outer appearances of the prepreg.
Therefore, the metal-clad laminate produced using them is excellent
in heat resistance and moisture when it absorbs moisture, and good
in drill-machinability and resistance to electric corrosion.
Moreover, it has excellent dielectric properties in a
high-frequency region, and hence is suitable for materials and
parts for printed-wiring boards for a variety of electric and
electronic devices which handle high-frequency signals.
[0034] The present invention discloses the subject matters in
Japanese Patent Application Nos. 2000-78792 and 2000-78796 filed on
Mar. 21, 2000, which are included in this specification after
referring to these applications.
BEST MODE FOR CARRYING OUT THE INVENTION
[0035] The cyanate compound (A) for the resin composition of the
present invention is not limited. The cyanate compounds useful for
the present invention include one or more compounds selected from
those represented by the general formula (I): ##STR1## (wherein,
R.sub.1 is an alkylene group of 1 to 3 carbon atoms, which may be
substituted by a halogen atom, or represented by the general
formula (II) or (III); R.sub.2, R.sub.2', R.sub.3, and R.sub.3' are
each hydrogen atom or an alkyl group of 1 to 4 carbon atoms,
preferably 1 to 3 carbon atoms, and may be the same or different,
even all of them may be the same; and R.sub.4 and R.sub.4' are each
an alkylene group of 1 to 3 carbon atoms, and may be the same or
different): ##STR2##
[0036] The preferable examples of R.sub.1 include: ##STR3##
[0037] More specifically, the cyanate compounds represented by the
general formula (I) include 2,2-bis(4-cyanatophenyl)propane,
bis(4-cyanatophenyl)ethane,
bis(3,5-dimethyl-4-cyanatophenyl)methane,
2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane,
.alpha.,.alpha.'-bis(4-cyanatophenyl)-m-diisopropylbenzene, and
cyanate-esterified phenol-added dicyclopentadiene polymer. These
compounds may be used either individually or in combination.
[0038] The phenol compound (B) for the resin composition of the
present invention is not limited. However, at least one monovalent
phenol compound selected from those represented by the general
formula (IV) or (V) is preferable: ##STR4## (wherein, R.sub.5 and
R.sub.6 are each hydrogen atom or methyl group, and may be the same
or different; "m" is an integer of 1 to 3; and the phenyl group may
be substituted by methyl, ethyl or propyl group, or halogen atom,
e.g., bromine, although not shown) ##STR5## (wherein, R.sub.7 and
R.sub.7' are each hydrogen atom or methyl group, and may be the
same or different; R.sub.8 is an alkyl group of 1 to 5 carbon
atoms, e.g., methyl, ethyl or 2,2-dimethylpropyl; and "n" is an
integer of 1 to 3, preferably 1 to 2)
[0039] The phenol compounds represented by the formula (IV) include
p-(.alpha.-cumyl)phenol, and mono-, di- or
tri-.alpha.-methylbenzyl)phenol. The phenol compounds represented
by the formula (V) include p-tert-butylphenol, 2,4- or
2,6-di-tert-butylphenol, p-tert-aminophenol and p-tert-octylphenol.
These phenol compounds may be used either individually or in
combination.
[0040] The phenol compound (B) is incorporated in the resin
composition of the present invention preferably at 0.025 to 0.30
equivalents of the phenolic hydroxylic group in the phenol compound
(B) per equivalent of the cyanato group in the cyanate compound (A)
(hydroxylic group/cyanato group ratio), more preferably 0.025 to
0.25, still more preferably 0.025 to 0.20. At a hydroxylic
group/cyanato group ratio below 0.025, dielectric properties of the
resin composition may not be sufficient, and there is a tendency
that its dielectric loss tangent cannot be sufficiently reduced. At
a ratio above 0.30, one the other hand, its dielectric loss tangent
may be conversely increased excessively and there is a tendency
that its heat resistance deteriorates while it is absorbing
moisture.
[0041] The cyanate compound (A) and phenol compound (B) for the
resin composition of the present invention may be replaced by a
phenol-modified cyanate ester oligomer produced by reacting the
cyanate compound (A) with the phenol compound (B) at an equivalent
ratio of the phenolic hydroxylic group in the phenol compound (B)
to the cyanato group in the cyanate compound (A) (hydroxylic
group/cyanato group ratio) in a range from 0.01 to 0.30, or also
may be replaced by a phenol compound (B) incorporated at an
equivalent ratio of the phenolic hydroxylic group in the phenol
compound (B) to the cyanato group in the cyanate compound (A)
(hydroxylic group/cyanato group ratio) in a range below 0.29.
[0042] Moreover, the intended object of the present invention can
be also achieved by use of a composition of the above-described
phenol-modified cyanate ester oligomer.
[0043] In the production of the phenol-modified cyanate ester
oligomer by the reaction between the cyanate compound (A) and
phenol compound (B), the required quantity of the phenol compound
(B) may be charged all at once from the initial stage of reaction,
or in installments. Quantity of the compound (B) other than the
initial charge is 0 to 0.29 equivalents of its phenolic hydroxylic
group per equivalent of the cyanato group in the cyanate compound
(A). Charging the additional compound (B) in excess of the above
level may deteriorate properties of the resultant resin compound,
e.g., dielectric properties and heat resistance while it is
absorbing moisture. It is particularly preferable to first charge
the compound (B) at 0.01 to 0.03 equivalents of its phenolic
hydroxylic group per equivalent of the cyanato group in the cyanate
compound (A) for the reaction with the compound (A), and then
charge the additional compound (B) at 0.15 to 0.29 equivalents of
its phenolic hydroxylic group per equivalent of the cyanato group
in the cyanate compound (A) as the starting compound after the
reaction in the first stage is completed. The phenol compound as
the initial charge for production of the phenol-modified cyanate
ester oligomer may be the same as, or different from, the
additional charge of the compound (B).
[0044] It is preferable, when the phenol compound is charged in
installments, to charge the phenol compound (B) at 0.025 to 0.3
equivalents of its phenolic hydroxylic group in total of the
initial and additional charges per equivalent of the cyanato group
in the cyanate compound (A).
[0045] The phenol compound as the initial charge for production of
the phenol-modified cyanate ester oligomer may be the same as, or
different from, the additional charge of the compound (B). Two or
more types of phenol compounds may be used for production of the
phenol-modified cyanate ester oligomer.
[0046] The phenol-modified cyanate ester oligomer produced by the
reaction between the cyanate compound (A) and phenol compound (B)
is a mixture comprising the cyanate ester oligomers (mainly trimer,
pentamer, heptamer, nonamer and undecamer) produced by cyclization
of the cyanate compound (A) itself to form triazine rings; modified
(imido-carbonated) oligomers with the phenolic hydroxylic group in
the phenol compound (B) added to the cyanato group in the cyanate
compound (A); and modified oligomers with 1 or 2 molecules of the
phenol compound (B) included in the structure which constitutes the
triazine ring, i.e., the compound with 1 or 2 out of 3 chains
extending from the triazine ring substituted by the molecules
derived from the phenol compound.
[0047] When the cyanate compound (A) is represented by the
following formula (I-1), the phenol compound (B) is represented by
the following formula (I-2), the resultant trimers as the cyanate
ester oligomers are represented by one of the following formulae
(I-3), (I-4) and (I-5), and imido-carbonated modified oligomers are
represented by the formula (I-6). ##STR6##
[0048] The phenol-modified cyanate ester oligomer has a
number-average molecular weight of 380 to 2,500, and particularly
preferably 800 to 2,000. The compound having a number-average
molecular weight below 380 may cause recrystallization of the
cyanate monomer in a solvent, when it is dissolved in that solvent
to produce the varnish, because the cyanate compound (A) is highly
crystalline. This type of problem will also occur when the cyanate
compound (A) is converted. On the other hand, the compound having a
number-average molecular weight above 2,500 may cause other
problems when used to produce a varnish: the resultant varnish may
be excessively viscous, making the base material of glass or the
like difficult to be impregnated therewith, and deteriorating
surface smoothness of the resultant prepreg; it may gel too
quickly, making spreading difficult; and it may lose storage
stability (pot life).
[0049] The phenol-modified cyanate ester oligomer and polyphenylene
ether resin (C) for the resin composition of the present invention
may be replaced by the phenol-modified cyanate ester oligomer
containing a polyphenylene ether resin, produced by reacting the
cyanate compound (A) with the phenol compound (B) in the presence
of the polyphenylene ether resin (C). More specifically, the
phenol-modified cyanate ester oligomer containing a polyphenylene
ether resin, which may be dissolved in a solution, is produced by
reacting the cyanate compound (A) with the phenol compound (B) in
the polyphenylene ether resin (C) being molten under heating or
dissolved in a solvent at an equivalent ratio of the phenolic
hydroxylic group in the phenol compound (B) to the cyanato group in
the cyanate compound (A) (hydroxylic group/cyanato group ratio) in
a range from 0.01 to 0.30. This procedure gives the resin of the
so-called "semi-interpenetrating polymer network (semi-IPN), in
which the phenol-modified cyanate oligomer and polyphenylene ether
resin are uniformly dissolved in each other.
[0050] When the phenol-modified cyanate ester oligomer or
phenol-modified cyanate ester oligomer containing a polyphenylene
ether resin is used for the resin composition of the present
invention, the cyanate compound (A) is reacted to produce the
oligomer at a conversion of preferably 10 to 70% by mol, estimated
by gel permeation chromatography, more preferably 20 to 70%. At a
conversion of the cyanate compound (A) below 10%, the unreacted
cyanate compound (A), which is highly crystalline, may be
recrystallized in a solvent, when the phenol-modified cyanate ester
oligomer or phenol-modified cyanate ester oligomer containing a
polyphenylene ether resin is dissolved in that solvent to produce
the varnish. At a conversion of the cyanate compound (A) above 70%,
on the other hand, it may cause other problems when used to produce
a varnish: the resultant varnish may be excessively viscous, making
the base material of glass or the like difficult to be impregnated
therewith, and deteriorating surface smoothness of the resultant
prepreg; it may gel too quickly, making spreading difficult; and it
may lose storage stability (pot life).
[0051] The compounds useful for the polyphenylene ether resin (C)
for the resin composition of the present invention include
poly(2,6-dimethyl-1,4-phenylene) ether, alloyed polymer of
poly(2,6-dimethyl-1,4-phenylene) ether and polystyrene, and alloyed
polymer of poly(2,6-dimethyl-1,4-phenylene) ether and
styrene/butadiene copolymer. The alloyed polymer of
poly(2,6-dimethyl-1,4-phenylene) ether and polystyrene, or alloyed
polymer of poly(2,6-dimethyl-1,4-phenylene) ether and
styrene/butadiene copolymer, when used for the present invention,
preferably contains the poly(2,6-dimethyl-1,4-phenylene) ether
component at 50% or more.
[0052] The polyphenylene ether resin (C) is incorporated preferably
at 5 to 300 parts by weight per 100 parts by weight of the cyanate
compound (A), more preferably 10 to 250 parts, still more
preferably 15 to 220 parts. It is incorporated preferably at 5
parts by weight to secure the sufficient dielectric properties of
the resin composition. When incorporated at the above 300 parts by
weight, it may cause insufficient fluidity of the resin composition
due to excessively increased viscosity, and hence deteriorate its
formability and the reactivity of the cyanate compound (A).
[0053] The silicone polymer (D) for the resin composition of the
present invention has at least one siloxane unit selected from the
group consisting of a tri-functional siloxane unit represented by
the formula RSiO.sub.3/2 (wherein, R is an organic group, and when
2 or more Rs are present in the silicone polymer, they may be the
same or different) and tetra-functional siloxane unit represented
by SiO.sub.4/2, polymerization degree of 7,000 or less, and at
least one terminal functional group reactive with hydroxyl group.
The polymerization degree is preferably 3 or more, more preferably
3 to 1,000. It is estimated from molecular weight of the polymer in
the case of low polymerization degree, or from number-average
molecular weight of the polymer determined by gel permeation
chromatography with a calibration curve of the standard polystyrene
or polyethylene glycol. The silicone polymer (D) may contain, in
addition to the tri- or tetra-functional siloxane unit, a
bi-functional siloxane unit represented by RSiO.sub.2/2 (wherein,
R.sub.2 is an organic group, and when 2 or more R.sub.2s are
present in the silicone polymer, they may be the same or
different).
[0054] R for the tri- and bi-functional siloxane units is an alkyl
group of 1 to 4 carbon atoms, phenyl group or the like, and the
functional group reactive with hydroxyl group is silanol group,
alkoxy group of 1 to 4 carbon atoms, acyloxy group of 1 to 4 carbon
atoms, halogen atom, e.g., chlorine or bromine, or the like.
[0055] The tetra-functional siloxane unit may contain 1 to 3
residual hydrolysable or OH groups, tri-functional siloxane unit
may contain 1 to 2 residual hydrolysable or OH groups, and
bi-functional siloxane unit may contain a residual hydrolysable or
OH group.
[0056] The silicone polymer (D) for the present invention has at
least one siloxane unit selected from the group consisting of a
three-dimensionally crosslinked tri- and tetra-functional group, or
a three-dimensionally crosslinked tri-, tetra- and bi-functional
group. These groups are three-dimensionally crosslinked without
being completely set or gelled. That they are not completely set or
gelled can be confirmed by, e.g., the dissolution of the silicone
polymer in a reaction solvent. The silicone polymer (D) is
preferably composed of a tri-functional siloxane unit alone,
tetra-functional siloxane unit alone, bi- and tri-functional
siloxane unit, bi- and tetra-functional siloxane unit, tri- and
tetra-functional siloxane unit, or bi-, tri- and tetra-functional
siloxane unit. For the content of each siloxane unit, the tetra- or
tri-functional siloxane unit accounts for 15 to 100% of the total
siloxane units, preferably 20 to 100%; and the bi-functional
siloxane unit for 0 to 85%, preferably 0 to 80%, all percentages in
mol. It is particularly preferable that the silicone polymer (D)
contains the tetra-functional siloxane unit at 15 to 100%, more
preferably 20 to 60%, tri-functional siloxane unit at 0 to 85%,
more preferably 0 to 80%, and bi-functional siloxane unit at 0 to
85%, more preferably 0 to 80%.
[0057] The silicone polymer (D) for the present invention is
produced by hydrolysis and subsequent polycondensation of a silane
compound, represented by the general formula R'.sub.nSiX.sub.4-n
(XI) (wherein, R' is a non-reactive group, e.g., an alkyl group of
1 to 4 carbon atoms or aryl group, e.g., phenyl group, which may
have a substituent, e.g., an alkyl group of 1 to 4 carbon atoms or
halogen atom; X is a group which can be hydrolyzed to form OH
group, e.g., a halogen atom (chlorine, bromine or the like) or
--OR; R is an alkyl group of 1 to 4 carbon atoms or alkyl carbonyl
group of 1 to 4 carbon atoms; and "n" is an integer of 0 to 2).
[0058] More specifically, the silane compounds represented by the
above general formula include
tetra-functional silane compounds, e.g.,
tetraalkoxysilanes (functionality of the silane compound means that
it has a condensable functional group), e.g.,
[0059] Si(OCH.sub.3).sub.4, Si(OC.sub.2H.sub.5).sub.4,
Si(OC.sub.3H.sub.7).sub.4 and Si(OC.sub.4H.sub.9).sub.4;
tri-functional silane compounds, e.g., monoalkyl trialkoxysilanes,
e.g., [0060] H.sub.3CSi(OCH.sub.3).sub.3,
H.sub.5C.sub.2Si(OCH.sub.3).sub.3,
H.sub.7C.sub.3Si(OCH.sub.3).sub.3,
H.sub.9C.sub.4Si(OCH.sub.3).sub.3,
H.sub.3CSi(OC.sub.2H.sub.5).sub.3,
H.sub.5C.sub.2Si(OC.sub.2H.sub.5).sub.3,
H.sub.7C.sub.3Si(OC.sub.2H.sub.5).sub.3,
H.sub.9C.sub.4Si(OC.sub.2H.sub.5).sub.3,
H.sub.3CSi(OC.sub.3H.sub.7).sub.3,
H.sub.5C.sub.2Si(OC.sub.3H.sub.7).sub.3,
H.sub.7C.sub.3Si(OC.sub.3H.sub.7).sub.3,
H.sub.9C.sub.4Si(OC.sub.3H.sub.7).sub.3,
H.sub.3CSi(OC.sub.4H.sub.9).sub.3,
H.sub.5C.sub.2Si(OC.sub.4H.sub.9).sub.3,
H.sub.7C.sub.3Si(OC.sub.4H.sub.9).sub.3 and
H.sub.9C.sub.4Si(OC.sub.4H.sub.9).sub.3, phenyl trialkoxysilane,
e.g., [0061] PhSi(OCH.sub.3).sub.3, PhSi(OC.sub.2H.sub.5).sub.3,
PhSi(OC.sub.3H.sub.7).sub.3 and PhSi(OC.sub.4H.sub.9).sub.3,
(wherein, Ph is phenyl group), monoalkyl triacyloxysilane, e.g.,
[0062] (H.sub.3CCOO).sub.3SiCH.sub.3,
(H.sub.3CCOO).sub.3SiC.sub.2H.sub.5,
(H.sub.3CCOO).sub.3SiC.sub.3H.sub.7 and
(H.sub.3CCOO).sub.3SiC.sub.4H.sub.9, and monoalkyl
trihalogenosilanes, e.g., [0063] Cl.sub.3SiCH.sub.3,
Cl.sub.3SiC.sub.2H.sub.5, Cl.sub.3SiC.sub.3H.sub.7,
Cl.sub.3SiC.sub.4H.sub.9, Br.sub.3SiCH.sub.3,
Br.sub.3SiC.sub.2H.sub.5, Br.sub.3SiC.sub.3H.sub.7 and
Br.sub.3SiC.sub.4H.sub.9; and bi-functional silane compounds, e.g.,
dialkyl dialkoxysilanes, e.g., [0064]
(H.sub.3C).sub.2Si(OCH.sub.3).sub.2,
(HC.sub.2).sub.2Si(OCH.sub.3).sub.2,
(H.sub.7C.sub.3).sub.2Si(OCH.sub.3).sub.2,
(H.sub.9C.sub.4).sub.2Si(OCH.sub.3).sub.2,
(H.sub.3C).sub.2Si(OC.sub.2H.sub.5).sub.2,
(H.sub.5C.sub.2).sub.2Si(OC.sub.2H.sub.5).sub.2,
(H.sub.7C.sub.3).sub.2Si(OC.sub.2H.sub.5).sub.2,
(H.sub.9C.sub.4).sub.2Si(OC.sub.2H.sub.5).sub.2,
(H.sub.3C).sub.2Si(OC.sub.3H.sub.7).sub.2,
(H.sub.5C.sub.2).sub.2Si(OC.sub.3H.sub.7).sub.2,
(H.sub.7C.sub.3).sub.2Si(OC.sub.3H.sub.7).sub.2,
(H.sub.9C.sub.4).sub.2Si(OC.sub.3H.sub.7).sub.2,
(H.sub.3C).sub.2Si(OC.sub.4H.sub.9).sub.2,
(H.sub.5C.sub.2).sub.2Si(OC.sub.4H.sub.9).sub.2,
(H.sub.7C.sub.3).sub.2Si(OC.sub.4H.sub.9).sub.2 and
(H.sub.9C.sub.4).sub.2Si(OC.sub.4H.sub.9).sub.2, diphenyl
dialkoxysilanes, e.g., [0065] Ph.sub.2Si(OCH.sub.3).sub.2 and
Ph.sub.2Si(OC.sub.2H.sub.5).sub.2, dialkyl diacyloxysilanes, e.g.,
[0066] (H.sub.3CCOO).sub.2Si(CH.sub.3).sub.2,
(H.sub.3CCOO).sub.2Si(C.sub.2H.sub.5).sub.2,
(H.sub.3CCOO).sub.2Si(C.sub.3H.sub.7).sub.2 and [0067]
(H.sub.3CCOO).sub.2Si(C.sub.4H.sub.9).sub.2 and dihalogenosilanes,
e.g., [0068] Cl.sub.2Si(CH.sub.3).sub.2,
Cl.sub.2Si(C.sub.2H.sub.5).sub.2, Cl.sub.2Si(C.sub.3H.sub.7).sub.2,
Cl.sub.2Si(C.sub.4H.sub.9).sub.2, Br.sub.2Si(CH.sub.3).sub.2,
Br.sub.2Si(C.sub.2H.sub.5).sub.2, Br.sub.2Si(C.sub.3H.sub.7).sub.2
and Br.sub.2Si(C.sub.4H.sub.9).sub.2.
[0069] The silane compound for the present invention, represented
by the general formula R'.sub.nSiX.sub.4-n (XI), contains a tetra-
or tri-functional silane compound as the essential component, and
may contain a bi-functional silane compound as required. In
particular, the preferable tetra-functional silane compound is
tetraalkoxysilane, the preferable tri-functional silane compound is
monoalkyl trialkoxysilane, and the preferable bi-functional silane
compound is dialkyl dialkoxysilane.
[0070] The tetra- or tri-functional silane compound is incorporated
preferably at 15 to 100%, more preferably 20 to 100%; bi-functional
silane compound preferably at 0 to 85%, more preferably 0 to 80%;
in particular, the tetra-functional silane compound more preferably
at 15 to 100%, still more preferably 20 to 100%; tri-functional
silane compound more preferably at 0 to 85%, still more preferably
0 to 80%; and bi-functional silane compound more preferably at 0 to
85%, still more preferably 0 to 80%, all percentages by mol.
[0071] The silicone polymer (D) for the present invention is
produced, as described above, by hydrolysis and subsequent
polycondensation of a silane compound, represented by the general
formula (XI), preferably in the presence of an organic or inorganic
acid or the like as the catalyst. The inorganic acids useful for
the present invention include hydrochloric, sulfuric, phosphoric,
nitric and hydrofluoric acid, and organic acids useful for the
present invention include oxalic, maleic, sulfonic and formic acid.
A Basic catalyst, e.g., ammonia or trimethyl ammonium, may be also
used. The quantity of the catalyst to be used is adequately set in
accordance with quantity of the silane compound represented by the
general formula (XI). It is however used preferably at 0.001 to 0.5
mols per mol of the silane compound represented by the general
formula (XI).
[0072] The hydrolysis and subsequent polycondensation are
preferably effected in a solvent, in the presence of water, as
required. The quantity of water to be used is set adequately.
However, it is preferably used at 5 mols or less per mol of the
silane compound represented by the general formula (XI), more
preferably 0.5 to 4 mols, because some problems, e.g., deteriorated
storage stability of the coating solution, may occur when it is
present in an excessive quantity.
[0073] The silicone polymer is produced under the above conditions,
while the composition is set in such a way that it is not
gelled.
[0074] The silicone polymer is preferably dissolved in the same
reaction solvent as described above before use for workability.
Therefore, a solution may be used without exchange, or the silicone
polymer may be dissolved in the above solvent after being separated
from the effluent solution.
[0075] The inorganic filler (E) for the present invention is not
limited. The fillers suitable for the present invention include
alumina, titanium oxide, mica, silica, beryllia, barium titanate,
potassium titanate, strontium titanate, calcium titanate, aluminum
carbonate, aluminum hydroxide, aluminum silicate, calcium
carbonate, calcium silicate, magnesium silicate, silicon nitride,
boron nitride, clay (e.g., fired clay), talc, aluminum borate, and
silicon carbide. These fillers may be used either individually or
in combination. Shape and size of the inorganic filler are not
limited. However, the suitably used one generally has a particle
size of 0.01 to 50 .mu.m, preferably 0.1 to 15 .mu.m. The quantity
of the inorganic filler is also not limited. However, it is
preferably incorporated at 1 to 1,000 parts by weight per 100 parts
by weight of total of the cyanate compound (A), phenol compound (B)
and polyphenylene ether resin (C), which is used as required, more
preferably 1 to 800 parts by weight.
[0076] The resin composition of the present invention is also
characterized by containing the inorganic filler (F) which is the
inorganic filler (F) surface-treated with the silicone polymer (D).
Use of the surface-treated inorganic filler (F) brings the effect
of the present invention more notably. The method of surface
treatment of the inorganic filler with the silicone polymer (D) is
not limited. The inorganic filler may be treated by the dry process
in which the silicone polymer (D) and inorganic filler (E) are
mixed directly with each other, or by the wet process in which the
inorganic filler (E) is mixed with a diluted treatment solution of
the silicone polymer (D). The quantity of the silicone polymer (D)
deposited on the inorganic filler is not limited. However,
generally it is preferably 0.01 to 20% by weight on the inorganic
filler, more preferably 0.05 to 10%, still more preferably 0.1 to
7%. When it is below 0.01%, the inorganic filler may be
insufficiently dispersed in the resin material, possibly
deteriorating electrical insulation reliability of the resin
composition. When it is above 20%, on the other hand, the resin
composition may have deteriorated properties, e.g., heat
resistance.
[0077] When the wet process, which uses the diluted treatment
solution, is adopted for the surface treatment of the inorganic
filler with the silicone polymer (D), the solvent for diluting the
silicone polymer (D) is not limited. Suitable solvents for the
present invention include alcohols, e.g., methanol, ethanol,
ethylene glycol and ethylene glycol monomethyl ether; ketones,
e.g., acetone, methylethylketone, methylisobutylketone and
cyclohexanone; aromatic hydrocarbons, e.g., toluene, xylene and
mesitylene; ester-based ones, e.g., methoxyethyl acetate,
ethoxyethyl acetate, butoxyethyl acetate and ethyl acetate; amides,
e.g., N-methylpyrrolidone, formamide, N-methylformamide,
N,N-dimethylformamide and N,N-dimethylacetoamide; and nitrites and
water. They may be used either individually or in combination.
[0078] When a solvent is used, its suitable quantity is not
limited. However, it is generally set to keep the non-volatile
content of the silicone polymer (D) at 0.01 to 90% by weight,
preferably 0.01 to 80%. Surface treatment temperature is not
limited. The inorganic filler may be treated at room temperature,
or at the reflux temperature for the solvent used or lower.
[0079] When the inorganic filler is treated with the silicone
polymer, the filler is preferably mixed with a solution of the
silicone polymer, and use of the resultant mixture is preferable
for workability. Care shall be taken not to completely set or gel
the silicone polymer during the mixing step, for which mixing
temperature is preferably set at room temperature to 200.degree.
C., more preferably 150.degree. C. or lower.
[0080] The inorganic filler surface-treated with the silicone
polymer may be produced by a procedure in which the inorganic
filler is immersed in a solution of the silicone polymer, and the
resultant filler coated with the polymer is separated and dried.
Care shall be taken in this case to prevent the filler particles
from agglomerating with each other due to the reaction with the
polymer. For this reason, the drying temperature for the treatment
is preferably set at 50 to 200.degree. C., more preferably 80 to
150.degree. C., and the drying time is preferably set at 5 to 60
minutes, more preferably 10 to 30 minutes.
[0081] In the present invention, the inorganic filler may be
surface-treated with a conventional coupling agent together with
the silicone polymer (D). The coupling agents useful for the
present invention include silane- and titanate-based ones. The
silane-based coupling agents include epoxysilane-based ones, e.g.,
.gamma.-glycidoxypropyltrimethoxy silane; aminosilane-based ones,
e.g., hydrochloride of
N-.beta.-(N-vinylbenzylaminoethyl)-.gamma.-aminopropyltrimethoxysilane;
and cationic silane-, vinyl silane-, acrylic silane- and mercapto
silane-based one, and a mixture thereof. The suitable
titanate-based coupling agents include
isopropyltris(dioctylpyrophosphate)titanate. These coupling agents
may be used either individually, or mixed in a desired ratio.
[0082] The ratio of the coupling agent to the silicone polymer,
when the former is used, is not limited. However, a suitable ratio
is generally 0.001:1 to 1:0.001 by weight, preferably 0.001:1 to
1:1, to allow them to efficiently exhibit their own
characteristics.
[0083] Moreover, the resin composition of the present invention may
be incorporated with a variety of resins or additives, e.g.,
flame-retardant (G), epoxy resin (H) or antioxidant (I), as
required, within limits not harmful to characteristics of the resin
composition, e.g., dielectric the properties or heat resistance,
when it is used for a printed-wiring board.
[0084] The flame-retardant (G), when incorporated in the resin
composition of the present invention, is not limited. It is
particularly preferable to have no functional group reactive with
the cyanate compound (A). It is also preferable, even if it is
reactive with the cyanate compound (A), when it is a polymer having
a sufficiently high molecular weight to exert only a limited effect
of the functional group at the terminal, because such a
flame-retardant is sufficiently low in reactivity with the cyanate
compound (A) to provide the resin composition with flame-retardancy
without damaging its dielectric properties after it is set. For
example, suitable flame-retardants for the present invention
include 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane,
tetrabromocyclooctane, hexabromocyclododecane,
bis(tribromophenoxy)ethane, a brominated triphenylcyanurate
represented by the formula (VI), brominated polyphenylene ether
represented by the formula (VII) and brominated polystyrene
represented by the formula (VIII). The flame-retardant, when used,
is incorporated preferably at 5 to 80 parts by weight per 100 parts
by weight of total of the cyanate compound (A), phenol compound
(B), and the components used as required, e.g., polyphenylene ether
resin (C) and another resin material containing, as required, an
additive (except for the inorganic filler), more preferably 5 to 60
parts, and still more preferably 5 to 50 parts. The resin
composition may not have sufficient flame-retardancy, when the
retardant is incorporated at below 5 parts by weight. On the other
hand, it may not have sufficient heat resistance after being set,
if it is incorporated at above 80 parts by weight: ##STR7##
(wherein, "l," "m," and "n" are each an integer of 1 to 5) ##STR8##
(wherein, "n" is an integer of 1 to 5) ##STR9## (wherein, "m," is
an integer of 1 to 5, and "n" is an integer).
[0085] The epoxy rein (H), when incorporated in the resin
composition of the present invention, is not limited. Those epoxy
resins suitably used for the epoxy resin (H) include bisphenol A
type epoxy resin, brominated bisphenol A type epoxy resin, phenol
novolac type epoxy resin, cresol novolac type epoxy resin,
bisphenol A novolac type epoxy resin, biphenyl type epoxy resin,
epoxy resin having a naphthalene structure, epoxy resin having an
aralkyl structure, phenol salicylaldehyde novolac type epoxy resin
represented by the following formula (IX), which may be substituted
by a lower alkyl group, and epoxy resin having a cyclopentadiene
structure, represented by the following formula (X): ##STR10##
(wherein, R.sub.9 is hydrogen atom or an alkyl group of 1 to 4
carbon atoms; R.sub.10 is an alkyl group of 1 to 4 carbon atoms;
and "n" is an average of 1 to 7) ##STR11## (wherein, "n" is an
integer).
[0086] The quantity of the epoxy resin, when used, is not
limited.
[0087] However, it is incorporated preferably to have 1.2
equivalents or less of the glycidyl group in the epoxy resin per
equivalent of the cyanato group in the cyanate compound (A), more
preferably 1 equivalent or less. Incorporation of the epoxy resin
to have an equivalence ratio above 1.2 may deteriorate dielectric
properties of the resultant resin composition in a high-frequency
bandwidth.
[0088] The antioxidant (I), when used, is selected from the group
consisting of a phenol-based one and organosulfur-based one. The
inventors of the present invention have found that incorporation of
the antioxidant controls metal migration in the resin composition,
when it is set or formed into a laminate, thereby further improving
its insulation reliability. The specific examples of the
phenol-based antioxidants useful for the present invention include
monophenol-based ones, e.g., pyrogallol, butylated hydroxyanisole
and 2,6-di-tert-butyl-4-methylpohenol; bisphenol-based ones, e.g.,
2,2'-methylene-bis-(4-methyl-6-tert-butyl phenol and
4,4'-thiobis-(3-methyl-6-tert-butyl phenol; and polymer type
phenol-based ones, e.g.,
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene
and
tetrakis-[methylene-3-(3'-5'-di-tert-butyl-4'-hydroxyphenyl)propionate]me-
thane. The specific examples of the organosulfur-based antioxidants
include dilauryl thiodipropionate and distearyl thiodipropionate.
These antioxidants may be used either individually or in
combination. The antioxidant, when used, is incorporated preferably
at 0.1 to 30 parts by weight per 100 parts by weight of total of
the cyanate compound (A), phenol compound (B), and the components
used as required, e.g., polyphenylene ether resin (C) and another
resin material containing, as required, an additive (except for the
inorganic filler). The resin composition may not exhibit improved
dielectric properties, when the antioxidant is incorporated at
below 0.1 parts by weight. On the other hand, its dielectric
properties may be conversely deteriorated, when it is incorporated
at above 30 parts by weight.
[0089] The resin composition of the present invention may be
further incorporated with a metal-based reaction catalyst, to
promote reaction of the cyanate compound (A). This catalyst works
to promote the setting reaction between the cyanate compound (A)
and phenol compound (B), and is used as the reaction promoter for
production of the phenol-modified cyanate ester oligomer and
phenol-modified cyanate ester oligomer containing the polyphenylene
ether resin for the present invention, or as the setting promoter
for production of the laminate. The metal-based catalysts useful
for the present invention include those based on manganese, iron,
cobalt, nickel, copper or zinc. More specifically, these metals are
in the form of organometal salt, e.g., 2-ethylhexanoate or
naphthenate; or organometal complex, e.g., acetylacetone complex.
The process for producing the phenol-modified cyanate ester
oligomer or phenol-modified cyanate ester oligomer containing the
polyphenylene ether resin and that for producing the laminate may
use the same metal-based reaction catalyst as the reaction promoter
and setting promoter, respectively, or different catalysts.
Moreover, each process may use one or more types of catalysts. The
metal-based reaction catalyst may be incorporated in the process
for producing the phenol-modified cyanate ester oligomer or
phenol-modified cyanate ester oligomer containing the polyphenylene
ether resin in a quantity required for promoting the reaction in
this process and for promoting the setting reaction in the
subsequent process for producing the laminate. Or else, the
catalyst may be incorporated in the former process in a quantity
required for promoting the reaction in that process, and the same
or a different one or a mixture thereof in the subsequent process
in a quantity for the remaining setting reaction in that
process.
[0090] When the epoxy resin (H) is incorporated in the resin
composition of the present invention, it may be used together with
a compound having a catalytic function to promote reaction of the
glycidyl group. Compounds useful for the present invention include
alkali metal compounds, alkali-earth metal compounds, imidazole
compounds, organophosphorus compounds, secondary amines, tertiary
amines and quaternary ammonium salts. They may be used either
individually or in combination.
[0091] The resin composition of the present invention, when set
under heating, can be used for producing a metal-clad laminate for
printed-wiring boards, excellent in dielectric characteristics and
heat resistance. More specifically, a base material, e.g., glass
cloth, is impregnated with the resin composition of the present
invention or varnish of the resin composition dissolved or
dispersed in a solvent, dried normally at 80 to 200.degree. C. by a
drying furnace or the like (or at temperature at which the solvent
can be evaporated or higher, when the solvent is used), preferably
100 to 180.degree. C., for 3 to 30 minutes, preferably 3 to 15
minutes, to prepare the prepreg. Next, the two or more prepreg
sheets are placed one on another to produce the laminate, which is
formed under heating, after being coated with a metallic foil on at
least one side, to produce the metal-clad laminate.
[0092] The solvent useful for dissolving or dispersing the resin
composition of the present invention to produce the varnish is not
limited. More specifically, the solvents useful for the present
invention include alcohols, e.g., methanol, ethanol, ethylene
glycol and ethylene glycol monomethyl ether; ketones, e.g.,
acetone, methylethylketone, methylisobutylketone and cyclohexanone;
aromatic hydrocarbons, e.g., toluene, xylene and mesitylene;
ester-based ones, e.g., methoxyethyl acetate, ethoxyethyl acetate,
butoxyethyl acetate and ethyl acetate; and amides, e.g.,
N-methylpyrrolidone, formamide, N-methylformamide,
N,N-dimethylformamide and N,N-dimethylacetoamide. They may be used
either individually or in combination. Of these solvents, a mixed
solvent of the aromatic hydrocarbon (e.g., toluene, xylene or
mesitylene) and ketone (e.g., acetone, methylethylketone,
methylisobutylketone or cyclohexanone) is more preferable for
producing the varnish of high non-volatile content and low
viscosity, when an inorganic filler treated with the silicone
polymer for the present invention is used.
[0093] The resin composition of the present invention, when used
for producing the varnish, may be dissolved or dispersed in the
above solvent, and further incorporated, as required, with a
variety of resins or additives, e.g., flame-retardant (G), epoxy
resin (H) or antioxidant (I).
[0094] The varnish may be produced by incorporating the cyanate
compound (A) or resin material containing the phenol-modified
cyanate oligomer and phenol compound (B), in the treatment solution
with the silicone polymer (D) dissolved in a solvent, in which the
inorganic filler (E) is surface-treated beforehand.
[0095] It may be also produced by dissolving or dispersing the
cyanate compound (A) or resin material containing the
phenol-modified cyanate oligomer and phenol compound (B), and then
incorporating, in the resultant solution or dispersion, the
treatment solution containing the inorganic filler (F)
surface-treated with the silicone polymer (D) dissolved in a
solvent, where the above solution or dispersion may be further
incorporated, as required, with a variety of resins or additives,
e.g., flame-retardant (G), epoxy resin (H) or antioxidant (I).
[0096] It may be also produced by incorporating, in the treatment
solution containing: the surface-treated inorganic filler (F),
cyanate compound (A), resin material containing the phenol-modified
cyanate oligomer and phenol compound (B) and polyphenylene ether
resin (C); or resin material containing the phenol-modified cyanate
oligomer containing the polyphenylene ether resin, produced in the
presence of the polyphenylene ether resin (C), and the phenol
compound (B), where the above treatment solution may be further
incorporated, as required, with a variety of resins or additives,
e.g., flame-retardant (G), epoxy resin (H) or antioxidant (I).
[0097] It may be also produced by incorporating the inorganic
filler (F) surface-treated with the silicone polymer (D) or
treatment solution containing the inorganic filler (F)
surface-treated with the silicone polymer (D) in the solvent which
dissolves or disperses resin materials containing the cyanate
compound (A) or the phenol-modified cyanate oligomer, phenol
compound (B) and polyphenylene ether resin (C), or resin material
containing the phenol-modified cyanate oligomer containing the
polyphenylene ether resin, produced in the presence of the
polyphenylene ether resin (C), and the phenol compound (B), where
the above solvent may further dissolve or disperse, as required, a
variety of resins or additives, e.g., flame-retardant (G), epoxy
resin (H) or antioxidant (I).
[0098] For production of the varnish, the phenol-modified cyanate
oligomer may be used in the form of solution produced by reacting
the cyanate compound (A) with the phenol compound (B) in a solvent,
or the phenol-modified cyanate oligomer containing the
polyphenylene ether resin may be used in the form of solution
produced by reacting the cyanate compound (A) with the phenol
compound (B) in the solvent which disperses or dissolves the
polyphenylene ether resin (C) beforehand.
[0099] In general, dielectric properties of a high-molecular-weight
material or the like are very sensitive to the effect of oriented
polarization. It is therefore possible to reduce its dielectric
constant by reducing the polar group in the molecule, or to reduce
its dielectric loss tangent by controlling movement of the polar
group. Although containing high-polarity cyanato group, a cyanate
ester resin, when set, has a characteristic of low relative
dielectric constant and dielectric loss tangent for a thermosetting
resin, because it is set with the cyanato group being consumed to
form a symmetric, rigid triazine structure.
[0100] However, the cyanato group in the cyanate ester resin alone
cannot be totally reacted to form the triazine structure, and left
as the unreacted cyanato group in the reaction system, which loses
fluidity as the setting reaction proceeds. As a result, the set
product only has a relative dielectric constant and dielectric loss
tangent higher than those which it could attain. Moreover, the
cyanate ester resin alone has problems, for example, deteriorated
fabricability, because of the sufficient hardness and fragileness,
and deteriorated heat resistance while it is absorbing moisture,
because of the high-polarity cyanato group left to increase its
water absorptivity.
[0101] Attempts have been made to improve fabricability and heat
resistance while the resin is absorbing moisture by incorporating
an epoxy resin, polyvalent phenol compound, imide or the like in
the cyanate ester resin. However, they involve their own
disadvantages, e.g., the formation of a high-polarity structure
other than the triazine ring by the reaction of the cyanato group,
and deteriorated dielectric properties of the resin composition,
because of decreased fluidity of the reaction system as the setting
reaction proceeds with the result that the unreacted functional
group (e.g., cyanato, glycidyl, hydroxyl or imide) tends to be left
in the system. These disadvantages are more notable when the resin
composition is used in a high-frequency bandwidth exceeding 1 GHz.
Incorporation of a polyvalent phenol compound in the cyanate ester
resin can improve the fabricability of the resultant resin
composition, but will greatly decrease its storage stability (pot
life). Moreover, the rapid reaction occurring during the resin
setting process greatly decreases its fluidity, preventing
efficient production of the triazine ring, and tending to leave the
unreacted cyanato group or hydroxyl group in the polyvalent phenol
compound and hence conversely deteriorate dielectric properties of
the resin composition.
[0102] By contrast, the resin composition of the present invention
is incorporated with an adequate quantity of the cyanate compound
and, in particular, monovalent phenol compound to efficiently form
the triazine ring. At the same time, the cyanato group left
unreacted in the resin composition is imido-carbonated to reduce
its polarity, thereby reducing the relative dielectric constant and
dielectric loss tangent of the resin composition after it is set.
Moreover, the inventors of the present invention have found that
the reaction between the cyanate compound and phenol compound forms
the triazine ring which contains a component derived from the
phenol compound. In the common setting process in which the cyanate
ester alone is set, because the triazine ring has 3 cyanato groups,
the triazine ring will invariably serve as the crosslinking point
as the reaction proceeds. By contrast, the triazine ring will not
serve as the crosslinking point in the resin composition of the
present invention, composed of the cyanate compound and monovalent
phenol compound, or of the phenol-modified cyanate ester oligomer,
because one or more molecules of the monovalent phenol compound
incorporated are included as the constituent component in the
triazine ring to decrease number of the cyanato group extending
from the triazine ring to 1 or 2. Therefore, the set resin
composition of the present invention characteristically has a
larger molecular weight between the crosslinking points and a lower
crosslinking density than the set product of the common cyanate
ester. The resin composition of the present invention increases in
viscosity to a lower extent as the setting reaction proceeds,
because of its larger molecular weight between the crosslinking
points. Therefore, the reaction system has a longer time before it
loses fluidity, keeping the cyanato group reactive for a longer
time and forming the triazine ring more efficiently. As a result,
the set resin composition can have improved dielectric properties,
because of the reduced quantity of the unreacted cyanato group left
in the composition. It is considered that the monovalent phenol
compound is more suitable for achieving the above objects, because
of its high reactivity with the cyanato group, mono-functionality
and relatively low molecular weight, and high compatibility with
the cyanate ester resin. The phenol compound (B) described earlier
as one suitable for the present invention is selected for the above
reasons.
[0103] A phenol compound, e.g., nonyl phenol, has been used as a
promoter for trimerization of a cyanate ester (to form the triazine
ring) at around 0.005 to 0.01 equivalents per equivalent of the
cyanate compound. However, it rarely brings the effect of reducing
polarity by the reaction of the unreacted cyanato group, because it
is used in a catalyst quantity. On the other hand, the inventors of
the present invention have found, after having studied quantity of
the phenol compound to be used, that incorporation of a larger
quantity of the phenol compound reduces the relative dielectric
constant and dielectric loss tangent of the set product, and that
use of the monovalent phenol compound, described earlier as the one
suitable for the present invention, can control the deterioration
of its heat resistance resulting from increased quantity of the
phenol compound. Therefore, the process of the present invention
gives the set resin composition having a lower relative dielectric
constant and dielectric loss tangent than the conventional set
products, e.g., that of the cyanate ester alone, or that of the
resin incorporated with an epoxy resin, polyvalent phenol compound,
imide or the like.
[0104] The resin composition of the present invention can have
still improved dielectric properties, when incorporated with a
polyphenylene ether resin, which is known as a thermoplastic resin
of good dielectric properties. A cyanate ester resin and
polyphenylene ether resin are inherently incompatible with each
other, and do not easily provide a uniform resin. The resin
composition of the present invention can have a uniform structure
due to its so-called "semi-interpenetrating polymer network
(semi-IPN), in which the setting component as one component is
crosslinked in the presence of the polymer (polyphenylene ether
resin in this case) as the other component while the resin
composition is being set or the phenol-modified cyanate oligomer
containing the polyphenylene ether resin is being produced. It is
considered that these components are eventually made compatible
with each other to form a uniform structure not via the chemical
bond but by oligomerization of the resin as one component while
being entwined with the molecular chains in the polymer. It is
considered to be advantageous for the resin composition to have the
semi-IPN structure that the reaction of the crosslinking component
proceeds in such a way to allow the crosslinking component to be
entwined more easily with the molecular chains in the polymer. In
this regard, the inventors of the present invention have found that
the phenol-modified cyanate ester resin as the crosslinking
component for the present invention is easily entwined with the
polyphenylene ether resin as the polymer component, because the
former has a longer molecular chain (or a larger molecular weight)
between the crosslinking points than the common set product of a
cyanate ester alone, as described earlier, with the result that
these components become more compatible with each other (the
triazine ring appears like a "knot" in each of the shorter
molecular chain in the common set product of a cyanate ester resin
alone).
[0105] The laminate or printed-wiring board of the resin
composition of the present invention, when incorporated with, as an
essential component, an inorganic filler surface-treated with a
silicone polymer, has a layer of the surface treatment agent
sufficiently covering the inorganic filler particles at the
interface between the inorganic filler and resin material, instead
of a thin, rigid layer of surface treatment agent formed in the
common process which uses a coupling agent or the like, where the
surface treatment agent layer in the resin composition of the
present invention works as a cushion formed by the
three-dimensionally crosslinked silicone polymer. As a result, the
inorganic filler particles agglomerate with each other less easily
than in the conventional resin containing a coupling agent, and
hence are dispersed more uniformly in the resin. Moreover, the
surface treatment agent layer works to relax the strain generated
at the interface between the inorganic filler and resin material,
performing a function of enabling the excellent adhesion property
interest to which the resin inherently has. Therefore, the laminate
and the printed-wiring board of the resin composition of the
present invention can exhibit excellent characteristics, e.g., low
water absorptivity, high drill-machinability and high insulation
reliability.
[0106] It is generally difficult to produce a varnish of high
non-volatile content and low viscosity, when a resin composition
containing a polyphenylene ether known as a high-molecular-weight
polymer is used. In other words, a varnish containing a
polyphenylene ether invariably has a problem of high solvent
content, because it will solidify to become a grease at normal
temperature as its non-volatile content increases. Use of a varnish
of a low non-volatile content to coat a base of glass cloth or the
like to produce a prepreg will cause problems of deteriorated
appearance of the resultant prepreg, decreased heat resistance of
the laminate for which the prepreg is used, because of increased
quantity of the solvent remaining in the prepreg, and difficulty in
securing the prepreg of desired resin content and thickness,
because of the limited quantity of resin deposited on the base of
glass cloth or the like. By contrast, the resin composition of the
present invention can be controlled for hydrophobicity
(hydrophilicity) of the silicone polymer as its component for
specific characteristics of the resin material and solvent by
adequately selecting the siloxane unit which constitutes the
silicone polymer. Therefore, the inorganic filler treated with the
silicone polymer, when used for the resin composition of the
present invention, works to adequately control interaction
(interfacial tension) between the resin material and solvent, resin
material and inorganic filler, and inorganic filler and solvent by
the action of the silicone polymer, bringing the advantages of
increased non-volatile content and improved workability of the
varnish for which the composition is used, the latter advantage
resulting from the adequately controlled viscosity.
[0107] It is also observed: that the set resin composition of the
present invention has a decreased dielectric constant and tangent,
when a sufficient quantity of the phenol compound is incorporated;
that use of the monovalent phenol compound can control decreases in
resistance of the composition to heat, where the decrease comes
from increased content of the silicone compound; and that foaming
problems do not occur while the prepreg of the composition is being
handled.
[0108] The present invention is described more specifically by
EXAMPLES, which by no means limit the present invention.
EXAMPLE 1
(Preparation of the Cyanate Resin Solution)
[0109] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 231 g of
toluene, 500 g of 2,2-bis(4-cyanatephenyl)propane (manufactured by
ASAHI CIBA CORPORATION; Arocy B-10) and 37.7 g of p-tert-butyl
phenol (manufactured by Kanto Chemical Co., Inc.). The mixture was
then incorporated with 0.13 g of manganese naphthenate
(manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction
promoter, after it was confirmed to be homogeneous and kept at
110.degree. C., and heated for 2-hours to synthesize the
phenol-modified cyanate oligomer solution, where the reaction
process was controlled to have a 2,2-bis(4-cyanatophenyl)propane
conversion of about 50%. This solution was used as the cyanate
resin solution. The 2,2-bis(4-cyanatophenyl)propane conversion was
51%, which was confirmed by gel permeation chromatography (GPC)
(Chromatograph: pump; manufactured by Hitachi, Ltd; L-6200, RI
detector; L-3300, and columns: Manufactured by TOSOH CORPORATION;
TSKgel-G4000H and 2000H, solvent: THF, concentration: 1%). The same
chromatograph was used in all EXAMPLES. It was also confirmed that
the elution peak of p-tert-butyl phenol disappeared, in all
EXAMPLES.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0110] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 16 g of
tetramethoxysilane and 24 g of methanol, to which 0.21 g of acetic
acid and 4.0 g of distilled water were added, and the mixture was
stirred at 50.degree. C. for 8 hours to synthesize the silicone
polymer with the siloxane unit having a polymerization degree of 20
(polymerization degree was estimated from number-average molecular
weight determined by GPC in all EXAMPLES). The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 371 g of methylethylketone and 915 g of silica
(average particle size: 0.5 .mu.m) as the inorganic filler. The
mixture was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0111] The treatment solution containing the inorganic filler
surface-treated with the silicone polymer was incorporated with the
cyanate resin solution prepared above, and the mixture was stirred
at 65.degree. C. for 1 hour to dissolve and disperse the cyanate
resin. The resultant solution was cooled to room temperature, and
incorporated with 0.06 g of zinc naphthenate (manufactured by Wako
Pure Chemical Industries, Ltd.) as a setting promoter and 161 g of
methylethylketone, to prepare the resin varnish containing
non-volatile content at around 65%.
EXAMPLE 2
(Preparation of the Cyanate Resin Solution)
[0112] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 273 g of
toluene, 500 g of bis(3,5-dimethyl-4-cyanatephenyl)methane
(manufactured by ASAHI CIBA CORPORATION; Arocy M-10) and 40.1 g of
p-tert-octyl phenol. The mixture was then incorporated with 0.25 g
of cobalt naphthenate as a reaction promoter, after it was
confirmed to be homogeneous and kept at 110.degree. C., and heated
for 2 hours to synthesize the phenol-modified cyanate oligomer
solution, where the reaction process was controlled to have a
bis(3,5-dimethyl-4-cyanatephenyl)methane conversion of 50%. The
resultant synthetic solution was incorporated with 97 g of
polystyrene bromide (manufactured by Great Lakes Chemical
Corporation; PDBS-80) as a flame-retardant, to prepare the cyanate
resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0113] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 21 g of
trimethoxymethylsilane and 31 g of methanol, to which 0.19 g of
acetic acid and 5.3 g of distilled water were added, and the
mixture was stirred at 50.degree. C. for 8 hours to synthesize the
silicone polymer with the siloxane unit having a polymerization
degree of 15. The resultant silicone polymer had methoxy and/or
silanol group as the terminal functional group reactive with
hydroxyl group. The solution containing the silicone polymer, put
in a 5-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer, was incorporated with 464 g
of methylethylketone and 1148 g of the same silica as used in
EXAMPLE 1 as the inorganic filler. The mixture was then stirred at
80.degree. C. for 1 hour to prepare the treatment solution
containing the inorganic filler surface-treated with the silicone
polymer.
(Preparation of the Resin Varnish)
[0114] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 0.06 g of zinc naphthenate
as a setting promoter and 199 g of methylethylketone, to prepare
the resin varnish containing non-volatile content at around
65%.
EXAMPLE 3
(Preparation of the Cyanate Resin Solution)
[0115] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 263 g of
toluene, 500 g of
.alpha.,.alpha.'-bis(4-cyanatophenyl)-m-diisopropylbenzene
(manufactured by ASAHI CIBA CORPORATION; RTX-366) and 10.4 g of
p-tert-octyl phenol. The mixture was then incorporated with 0.15 g
of iron naphthenate (manufactured by Kanto Chemical Co., Inc.) as a
reaction promoter, after it was confirmed to be homogeneous and
kept at 110.degree. C., and heated for 2 hours to synthesize the
phenol-modified cyanate oligomer solution, where the reaction
process was controlled to have an
.alpha.,.alpha.'-bis(4-cyanatophenyl)-m-diisopropylbenzene
conversion of 49%. The resultant synthetic solution was
incorporated with 103 g of brominated polyphenylene ether
(manufactured by Great Lakes Chemical Corporation; PO-64P) as a
flame-retardant, to prepare the cyanate resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0116] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 6.5 g of
dimethoxydimethylsilane, 13 g of trimethoxymethylsilane and 29 g of
methanol, to which 0.23 g of acetic acid and 4.9 g of distilled
water were added, and the mixture was stirred at 50.degree. C. for
8 hours to synthesize the silicone polymer with the siloxane unit
having a polymerization degree of 18. The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 520 g of methylethylketone and 1272 g of the same
silica as used in EXAMPLE 1 as the inorganic filler. The mixture
was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0117] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 22.7 g of p-tert-amyl
phenol (manufactured by TOKYO KASEI KOGYO CO., LTD), 0.06 g of zinc
naphthenate as a setting promoter and 222 g of methylethylketone,
to prepare the resin varnish containing non-volatile content at
around 65%.
EXAMPLE 4
(Preparation of the Cyanate Resin Solution)
[0118] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 254 g of
toluene, 500 g of 2,2-bis(4-cyanatophenyl)propane and 11.4 g of
p-(.alpha.-cumyl)phenol (manufactured by TOKYO KASEI KOGYO CO.,
LTD). The mixture was then incorporated with 0.13 g of zinc
naphthenate as a reaction promoter, after it was confirmed to be
homogeneous and kept at 110.degree. C., and heated for 3 hours to
synthesize the phenol-modified cyanate oligomer solution, where the
reaction process was controlled to have a
2,2-bis(4-cyanatophenyl)propane conversion of 50%. The resultant
synthetic solution was incorporated with 82 g of brominated
triphenyl cyanurate (manufactured by Dai-ichi Kogyo Seiyaku Co.,
Ltd; Pyroguard SR-245) as a flame-retardant, to prepare the cyanate
resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0119] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 10 g of
dimethoxydimethylsilane, 12 g of tetramethoxysilane and 33 g of
methanol, to which 0.3 g of acetic acid and 5.7 g of distilled
water were added, and the mixture was stirred at 50.degree. C. for
8 hours to synthesize the silicone polymer with the siloxane unit
having a polymerization degree of 28. The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 443 g of methylethylketone and 1102 g of the same
silica as used in EXAMPLE 1 as the inorganic filler. The mixture
was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0120] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 19.0 g of
p-(.alpha.-cumyl)phenol, 0.06 g of zinc naphthenate as a setting
promoter and 200 g of methylethylketone, to prepare the resin
varnish containing non-volatile content at around 65%.
EXAMPLE 5
(Preparation of the Cyanate Resin Solution)
[0121] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 262 g of
toluene, 500 g of bis(3,5-dimethyl-4-cyanatephenyl)methane and 31.9
g of p-tert-amyl phenol (manufactured by TOKYO KASEI KOGYO CO.,
LTD). The mixture was then incorporated with 0.13 g of zinc
naphthenate as a reaction promoter, after it was confirmed to be
homogeneous and kept at 110.degree. C., and heated for 2 hours to
synthesize the phenol-modified cyanate oligomer solution, where the
reaction process was controlled to have a
bis(3,5-dimethyl-4-cyanatephenyl)methane conversion of 49%. The
resultant synthetic solution was incorporated with 79 g of
bis(tribromophenoxy)ethane (manufactured by Great Lakes Chemical
Corporation; FF-680) as a flame-retardant, to prepare the cyanate
resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0122] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 6.5 g of
trimethoxymethylsilane, 8 g of tetramethoxysilane and 21 g of
methanol, to which 0.16 g of acetic acid and 3.6 g of distilled
water were added, and the mixture was stirred at 50.degree. C. for
8 hours to synthesize the silicone polymer with the siloxane unit
having a polymerization degree of 22. The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 413 g of methylethylketone and 1008 g of the same
silica as used in EXAMPLE 1 as the inorganic filler. The mixture
was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0123] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 0.06 g of zinc naphthenate
as a setting promoter and 179 g of methylethylketone, to prepare
the resin varnish containing non-volatile content at around
65%.
EXAMPLE 6
(Preparation of the Cyanate Resin Solution)
[0124] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 175 g of
toluene, 400 g of 2,2-bis(4-cyanatophenyl)propane and 8.6 g of
p-tert-bytyl phenol. The mixture was then incorporated with 0.1 g
of manganese naphthenate as a reaction promoter, after it was
confirmed to be homogeneous and kept at 110.degree. C., and heated
for 3 hours to synthesize the phenol-modified cyanate oligomer
solution, where the reaction process was controlled to have a
2,2-bis(4-cyanatophenyl)propane conversion of 52%. The resultant
synthetic solution was used as the cyanate resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0125] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 10 g of
dimethoxydimethylsilane, 10 g of trimethoxymethylsilane, 20 g of
tetramethoxysilane and 59 g of methanol, to which 0.51 g of acetic
acid and 10 g of distilled water were added, and the mixture was
stirred at 50.degree. C. for 8 hours to synthesize the silicone
polymer with the siloxane unit having a polymerization degree of
23. The resultant silicone polymer had methoxy and/or silanol group
as the terminal functional group reactive with hydroxyl group. The
solution containing the silicone polymer, put in a 5-liter
four-mouthed separable flask equipped with a thermometer, cooling
tube and stirrer, was incorporated with 1282 g of methylethylketone
and 3120 g of strontium titanate (average particle size: 1.0 .mu.m)
as the inorganic filler. The mixture was then stirred at 80.degree.
C. for 1 hour to prepare the treatment solution containing the
inorganic filler surface-treated with the silicone polymer.
(Preparation of the Resin Varnish)
[0126] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above and 460
g of brominated bisphenol A type epoxy resin (manufactured by
Sumitomo Chemical Company, Ltd; ESB400T) as the epoxy resin, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 21.9 g of
p-(.alpha.-cumyl)phenol, 0.05 g of zinc naphthenate as a setting
promoter and 652 g of methylethylketone, to prepare the resin
varnish containing non-volatile content at around 65%.
EXAMPLE 7
(Preparation of the Cyanate Resin Solution)
[0127] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 177 g of
toluene, 400 g of
2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane
(manufactured by ASAHI CIBA CORPORATION; Arocy F-10) and 12.8 g of
p-tert-octyl phenol. The mixture was then incorporated with 0.1 g
of manganese naphthenate as a reaction promoter, after it was
confirmed to be homogeneous and kept at 110.degree. C., and heated
for 3 hours to synthesize the phenol-modified cyanate oligomer
solution, where the reaction process was controlled to have a
2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane conversion
of 50%. The resultant synthetic solution was used as the cyanate
resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0128] A 5-liter four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 33.2 g of the solution
prepared in the same manner as in EXAMPLE 1 to contain the silicone
polymer, 6 g of .gamma.-glycidoxypropyltrimethoxysilane
(manufactured by Nippon Unicar Co., Ltd; A-187) as a silane-based
coupling agent at a ratio of the silicone polymer to A-187 of 2:1
by weight, 555 g of methylethylketone, and 1331 g of the same
silica as used in EXAMPLE 1 as the inorganic filler. The mixture
was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0129] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above and 266
g of an epoxy resin containing a dicyclopentadiene structure
(manufactured by Dainippon Ink and Chemicals, Inc.; HP-7200) as the
epoxy resin, and the mixture was stirred at 65.degree. C. for 1
hour to dissolve and disperse the cyanate resin. The resultant
solution was cooled to room temperature, and incorporated with 21.4
g of p-tert-octyl phenol, 0.05 g of zinc naphthenate as a setting
promoter and 348 g of methylethylketone, to prepare the resin
varnish containing non-volatile content at around 65%.
EXAMPLE 8
[0130] A 2-liter four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with the cyanate resin
solution prepared in the same manner as in EXAMPLE 1 and 532 g of
methylethylketone, and the mixture was stirred at 65.degree. C. for
1 hour to dissolve the cyanate resin. The resultant solution was
incorporated with the solution prepared in the same manner as in
EXAMPLE 1 to contain the silicone polymer, and stirred for 30
minutes, to which 915 g of the same silica as used in EXAMPLE 1 was
added as the inorganic filler, and the mixture was stirred for 1
hour to disperse the inorganic filler. The resultant solution was
cooled to room temperature, and incorporated with 0.06 g of zinc
naphthenate as a setting promoter, to prepare the resin varnish
containing non-volatile content at around 65%.
EXAMPLE 9
(Preparation of the Cyanate Resin Solution)
[0131] A 3-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 172 g of
toluene, 400 g of 2,2-bis(4-cyanatophenyl)propane (manufactured by
ASAHI CIBA CORPORATION; Arocy B-10) and 30.2 g of p-tert-butyl
phenol (manufactured by Kanto Chemical Co., Inc.). The mixture was
then incorporated with 0.1 g of manganese naphthenate (manufactured
by Wako Pure Chemical Industries, Ltd.) as a reaction promoter,
after it was confirmed to be homogeneous and kept at 110.degree.
C., and heated for 1 hour to synthesize the phenol-modified cyanate
oligomer solution. Conversion of the
2,2-bis(4-cyanatophenyl)propane was 41%, which was confirmed by gel
permeation chromatography (GPC) (Chromatograph: pump; manufactured
by Hitachi, Ltd; L-6200, RI detector; L-3300, and columns,
Manufactured by TOSHO CORPORATION, TSKgel-G4000H and 2000H,
solvent: THF, concentration: 1%). The same chromatograph was used
in all EXAMPLES. It was also confirmed that the elution peak of
p-tert-butyl phenol disappeared, in all EXAMPLES. The synthesized
solution was incorporated with a solution of 320 g of a
polyphenylene ether resin (manufactured by GE plastics Japan Ltd;
PKN4752) dissolved in 442 g of toluene under heating at 90.degree.
C., to prepare the cyanate resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0132] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 22 g of
tetramethoxysilane and 33 g of methanol, to which 0.29 g of acetic
acid and 5.6 g of distilled water were added, and the mixture was
stirred at 50.degree. C. for 8 hours to synthesize the silicone
polymer with the siloxane unit having a polymerization degree of 20
(polymerization degree was estimated from number-average molecular
weight determined by GPC in all EXAMPLES). The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 518 g of methylethylketone and 1275 g of silica
(average particle size: 0.5 .mu.m) as the inorganic filler. The
mixture was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0133] The treatment solution containing the inorganic filler
surface-treated with the silicone polymer was incorporated with the
cyanate resin solution prepared above, and the mixture was stirred
at 65.degree. C. for 1 hour to dissolve and disperse the cyanate
resin. The resultant solution was cooled to room temperature, and
incorporated with 0.05 g of zinc naphthenate (manufactured by Wako
Pure Chemical Industries, Ltd.) as a setting promoter and 506 g of
methylethylketone, to prepare the resin varnish containing
non-volatile content at around 56%.
EXAMPLE 10
(Preparation of the Cyanate Resin Solution)
[0134] A 3-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 293 g of
toluene, 400 g of bis(3,5-dimethyl-4-cyanatephenyl)methane
(manufactured by ASAHI CIBA CORPORATION; Arocy M-10) and 32.1 g of
p-tert-octyl phenol. The mixture was then incorporated with 0.15 g
of cobalt naphthenate (manufactured by Wako Pure Chemical
Industries, Ltd.) as a reaction promoter, after it was confirmed to
be homogeneous and kept at 110.degree. C., and heated for 1 hour to
synthesize the phenol-modified cyanate oligomer solution, where the
bis(3,5-dimethyl-4-cyanatephenyl)methane was converted at a rate of
40%. The resultant synthetic solution was incorporated with a
solution of 300 g of polyphenylene ether resin (PKN4752) dissolved
in 414 g of toluene under heating at 90.degree. C. and 132 g of
polystyrene bromide (manufactured by Great Lakes Chemical
Corporation; PDBS-80) as a flame-retardant, to prepare the cyanate
resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0135] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 29 g of
trimethoxymethylsilane and 43 g of methanol, to which 0.26 g of
acetic acid and 7.2 g of distilled water were added, and the
mixture was stirred at 50.degree. C. for 8 hours to synthesize the
silicone polymer with the siloxane unit having a polymerization
degree of 15. The resultant silicone polymer had methoxy and/or
silanol group as the terminal functional group reactive with
hydroxyl group. The solution containing the silicone polymer, put
in a 5-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer, was incorporated with 629 g
of methylethylketone and 1556 g of the same silica as used in
EXAMPLE 9 as the inorganic filler. The mixture was then stirred at
80.degree. C. for 1 hour to prepare the treatment solution
containing the inorganic filler surface-treated with the silicone
polymer.
(Preparation of the Resin Varnish)
[0136] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 0.05 g of zinc naphthenate
as a setting promoter and 538 g of methylethylketone, to prepare
the resin varnish containing non-volatile content at around
57%.
EXAMPLE 11
(Preparation of the Cyanate Resin Solution)
[0137] A 3-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 550 g of
toluene and 255 g of a polyphenylene ether resin (PKN4752), and the
mixture was stirred under heating at 90.degree. C. to dissolve the
resin. It was then incorporated with 300 g of
.alpha.,.alpha.'-bis(4-cyanatophenyl)-m-diisopropylbenzene
(manufactured by ASAHI CIBA CORPORATION; RTX-366) and 6.2 g of
p-tert-octyl phenol. The mixture was then incorporated with 0.1 g
of iron naphthenate (manufactured by Kanto Chemical Co., Inc.) as a
reaction promoter" after it was confirmed to be homogeneous and
kept at 110.degree. C., and heated for 1 hour to synthesize the
phenol-modified cyanate oligomer solution containing the
polyphenylene ether resin, where the
.alpha.,.alpha.'-bis(4-cyanatophenyl)-m-diisopropylbenzene was
converted at a rate of 39%. The resultant synthetic solution was
incorporated with 111 g of brominated polyphenylene ether
(manufactured by Great Lakes Chemical Corporation; PO-64P) as a
flame-retardant, to prepare the cyanate resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0138] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 7 g of
dimethoxydimethylsilane, 14 g of trimethoxymethylsilane and 32 g of
methanol, to which 0.25 g of acetic acid and 5.3 g of distilled
water were added, and the mixture was stirred at 50.degree. C. for
8 hours to synthesize the silicone polymer with the siloxane unit
having a polymerization degree of 18. The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 560 g of methylethylketone and 1371 g of the same
silica as used in EXAMPLE 9 as the inorganic filler. The mixture
was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0139] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 13.6 g of p-tert-amyl
phenol (manufactured by TOKYO KASEI KOGYO CO., LTD), 0.04 g of zinc
naphthenate as a setting promoter and 624 g of methylethylketone,
to prepare the resin varnish containing non-volatile content at
around 54%.
EXAMPLE 12
(Preparation of the Cyanate Resin Solution)
[0140] A 3-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 766 g of
toluene and 400 g of a polyphenylene ether resin (PKN4752), and the
mixture was stirred under heating at 90.degree. C. to dissolve the
resin. It was incorporated with 400 g of
2,2-bis(4-cyanatophenyl)propane and 9.2 g of
p-.alpha.-cumyl.)phenol (manufactured by TOKYO KASEI KOGYO CO.,
LTD). The mixture was then incorporated with 0.1 g of zinc
naphthenate as a reaction promoter, after it was confirmed to be
homogeneous and kept at 110.degree. C., and heated for 2 hours to
synthesize the phenol-modified cyanate oligomer solution containing
the polyphenylene ether resin, where the
2,2-bis(4-cyanatophenyl)propane was converted at a rate of 40%. The
resultant synthetic solution was incorporated with 127 g of
brominated triphenyl cyanurate (manufactured by Dai-ichi Kogyo
Seiyaku Co., Ltd; Pyroguard SR-245) as a flame-retardant, to
prepare the cyanate resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0141] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 16 g of
dimethoxydimethylsilane, 19 g of tetramethoxysilane and 52 g of
methanol, to which 0.46 g of acetic acid and 8.8 g of distilled
water were added, and the mixture was stirred at 50.degree. C. for
8 hours to synthesize the silicone polymer with the siloxane unit
having a polymerization degree of 28. The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 688 g of methylethylketone and 1713 g of the same
silica as used in EXAMPLE 9 as the inorganic filler. The mixture
was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0142] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve or
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 15.3 g of
p-(.alpha.-cumyl)phenol, 0.05 g of zinc naphthenate as a setting
promoter and 606 g of methylethylketone, to prepare the resin
varnish containing non-volatile content at around 56%.
EXAMPLE 13
(Preparation of the Cyanate Resin Solution)
[0143] A 3-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 775 g of
toluene and 400 g of a polyphenylene ether resin (PKN4752), and the
mixture was stirred under heating at 90.degree. C. to dissolve the
resin. It was incorporated with 400 g of
bis(3,5-dimethyl-4-cyanatophenyl)methane and 25.6 g of p-tert-amyl
phenol (manufactured by TOKYO KASEI KOGYO CO., LTD). The mixture
was then incorporated with 0.1 g of manganese naphthenate as a
reaction promoter, after it was confirmed to be homogeneous and
kept at 110.degree. C., and heated for 2 hours to synthesize the
phenol-modified cyanate oligomer solution containing the
polyphenylene ether resin, where the
bis(3,5-dimethyl-4-cyanatophenyl)methane was converted at a rate of
38%. The resultant synthetic solution was incorporated with 122 g
of bis(tribromophenoxy)ethane (manufactured by Great Lakes Chemical
Corporation; FF-680) as a flame-retardant, to prepare the cyanate
resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0144] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 10 g of
trimethoxymethylsilane, 12 g of tetramethoxysilane and 33 g of
methanol, to which 0.25 g of acetic acid and 5.6 g of distilled
water were added, and the mixture was stirred at 50.degree. C. for
8 hours to synthesize the silicone polymer with the siloxane unit
having a polymerization degree of 22. The resultant silicone
polymer had methoxy and/or silanol group as the terminal functional
group reactive with hydroxyl group. The solution containing the
silicone polymer, put in a 5-liter four-mouthed separable flask
equipped with a thermometer, cooling tube and stirrer, was
incorporated with 641 g of methylethylketone and 1563 g of the same
silica as used in EXAMPLE 9 as the inorganic filler. The mixture
was then stirred at 80.degree. C. for 1 hour to prepare the
treatment solution containing the inorganic filler surface-treated
with the silicone polymer.
(Preparation of the Resin Varnish)
[0145] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 0.05 g of zinc naphthenate
as a setting promoter and 618 g of methylethylketone, to prepare
the resin varnish containing non-volatile content at around
55%.
EXAMPLE 14
(Preparation of the Cyanate Resin Solution)
[0146] A 3-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 454 g of
toluene and 300 g of a polyphenylene ether resin (PKN4752), and the
mixture was stirred under heating at 90.degree. C. to dissolve the
resin. It was incorporated with 250 g of
2,2-bis(4-cyanatophenyl)propane and 5.4 g of p-tert-butyl phenol.
The mixture was then incorporated with 0.06 g of manganese
naphthenate as a reaction promoter, after it was confirmed to be
homogeneous and kept at 110.degree. C., and heated for 2 hours to
synthesize the phenol-modified cyanate oligomer solution containing
the polyphenylene ether resin, where the
2,2-bis(4-cyanatophenyl)propane was converted at a rate of 41%. The
resultant synthetic solution was used as the cyanate resin
solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0147] A 200-mL four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 10 g of
dimethoxydimethylsilane, 10 g of trimethoxymethylsilane, 20 g of
tetramethoxysilane and 59 g of methanol, to which 0.51 g of acetic
acid and 10 g of distilled water were added, and the mixture was
stirred at 50.degree. C. for 8 hours to synthesize the silicone
polymer with the siloxane unit having a polymerization degree of
23. The resultant silicone polymer had methoxy and/or silanol group
as the terminal functional group reactive with hydroxyl group. The
solution containing the silicone polymer, put in a 5-liter
four-mouthed separable flask equipped with a thermometer, cooling
tube and stirrer, was incorporated with 1234 g of methylethylketone
and 2999 g of strontium titanate (average particle size: 1.0 .mu.m)
as the inorganic filler. The mixture was then stirred at 80.degree.
C. for 1 hour to prepare the treatment solution containing the
inorganic filler surface-treated with the silicone polymer.
(Preparation of the Resin Varnish)
[0148] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above and 288
g of brominated bisphenol A type epoxy resin (manufactured by
Sumitomo Chemical Company, Ltd; ESB400T) as the epoxy resin, and
the mixture was stirred at 65.degree. C. for 1 hour to dissolve and
disperse the cyanate resin. The resultant solution was cooled to
room temperature, and incorporated with 13.7 g of
p-(.alpha.-cumyl)phenol, 0.03 g of zinc naphthenate as a setting
promoter and 531 g of methylethylketone, to prepare the resin
varnish containing non-volatile content at around 63%.
EXAMPLE 15
(Preparation of the Cyanate Resin Solution)
[0149] A 3-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 536 g of
toluene and 345 g of a polyphenylene ether resin (PKN4752), and the
mixture was stirred under heating at 90.degree. C. to dissolve the
resin. It was incorporated with 300 g of
2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane
(manufactured by ASAHI CIBA CORPORATION; Arocy F-10) and 9.6 g of
p-tert-octyl phenol. The mixture was then incorporated with 0.08 g
of manganese naphthenate as a reaction promoter, after it was
confirmed to be homogeneous and kept at 110.degree. C., and heated
for 2 hours to synthesize the phenol-modified cyanate oligomer
solution containing the polyphenylene ether resin, where the
2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane was
converted at a rate of 39%. The resultant synthetic solution was
used as the cyanate resin solution.
(Preparation of the Inorganic Filler Treated with the Silicone
Polymer)
[0150] A 5-liter four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with 41.3 g of the solution
prepared in the same manner as in EXAMPLE 1 to contain the silicone
polymer, 7.5 g of .gamma.-glycidoxypropyltrimethoxysilane
(manufactured by Nippon Unicar Co., Ltd; A-187) as a silane-based
coupling agent at a ratio of the silicone polymer to A-187 of 2:1
by weight, 689 g of methylethylketone, and 654 g of the same silica
as used in EXAMPLE 9 as the inorganic filler. The mixture was then
stirred at 80.degree. C. for 1 hour to prepare the treatment
solution containing the inorganic filler surface-treated with the
silicone polymer.
(Preparation of the Resin Varnish)
[0151] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above and 200
g of an epoxy resin containing a dicyclopentadiene structure
(manufactured by Dainippon Ink and Chemicals, Inc.; HP-7200) as the
epoxy resin, and the mixture was stirred at 65.degree. C. for 1
hour to dissolve and disperse the cyanate resin. The resultant
solution was cooled to room temperature, and incorporated with 16.1
g of p-tert-octyl phenol, 0.04 g of zinc naphthenate as a setting
promoter and 442 g of methylethylketone, to prepare the resin
varnish containing non-volatile content at around 60%.
EXAMPLE 16
[0152] A 5-liter four-mouthed flask equipped with a thermometer,
cooling tube and stirrer was charged with the cyanate resin
solution prepared in the same manner as in EXAMPLE 9 and 1024 g of
methylethylketone, and the mixture was stirred at 65.degree. C. for
1 hour to dissolve the cyanate resin. The resultant solution was
incorporated with the solution prepared in the same manner as in
EXAMPLE 9 to contain the silicone polymer, and stirred for 30
minutes, to which 1275 g of the same silica as used in EXAMPLE 9
was added as the inorganic filler, and the mixture was stirred for
1 hour to disperse the inorganic filler. The resultant solution was
cooled to room temperature, and incorporated with 0.05 g of zinc
naphthenate as a setting promoter, to prepare the resin varnish
containing non-volatile content at around 56%.
COMPARATIVE EXAMPLE 1
[0153] The cyanate resin solution prepared in the same manner as in
EXAMPLE 1 was incorporated with 551 g of methylethylketone and 915
g of the same silica as used in EXAMPLE 1 as the inorganic filler,
and the mixture was stirred at 65.degree. C. for 1 hour and then
cooled. The resultant solution was incorporated with 0.06 g of zinc
naphthenate as a setting promoter, to prepare the resin varnish
containing non-volatile content at around 65%.
COMPARATIVE EXAMPLE 2
[0154] A solution of 500 g of commercially available
2,2-bis(4-cyanatephenyl)propane oligomer (manufactured by ASAHI
CIBA CORPORATION; Arocy B-10) dissolved in 214 g of toluene was
prepared, and incorporated with 512 g of methylethylketone and 850
g of the same silica as used in EXAMPLE 1 as the inorganic filler.
The mixture was stirred at 65.degree. C. for 1 hour and then
cooled. The resultant solution was incorporated with 0.18 g of zinc
naphthenate as a setting promoter, to prepare the resin varnish
containing non-volatile content at around 65%.
COMPARATIVE EXAMPLE 3
[0155] A cyanate resin solution was prepared by dissolving 500 g of
commercially available 2,2-bis(4-cyanatephenyl)propane oligomer and
28.2 g of commercially available 2,2-bis(4-hydroxyphenyl)propane
(manufactured by Mitsui Chemicals, Inc.; bisphenol A) in 226 g of
toluene.
[0156] A treatment solution containing an inorganic filler
surface-treated with a coupling agent was prepared in the same
manner as in EXAMPLE 1, except that the silicone polymer-containing
solution was replaced by 16 g of
.gamma.-glycidoxypropyltrimethoxysilane (manufactured by Nippon
Unicar Co., Ltd; A-187) as a silane-based coupling agent.
[0157] Then, the treatment solution containing the inorganic filler
was incorporated with the cyanate resin solution prepared above and
158 g of methylethylketone, and the mixture was stirred at
65.degree. C. for 1 hour and then cooled. The resultant solution
was incorporated with 0.18 g of zinc naphthenate as a setting
promoter, to prepare the resin varnish containing non-volatile
content at around 65%.
COMPARATIVE EXAMPLE 4
[0158] A cyanate resin solution was prepared in the same manner as
in COMPARATIVE EXAMPLE 3, except that
2,2-bis(4-hydroxyphenyl)propane was replaced by 26.2 g of phenol
novolac (manufactured by Hitachi Chemical Co., Ltd; HP850N).
[0159] A treatment solution containing an inorganic filler
surface-treated with epoxy-modified silicone oil was prepared in
the same manner as in COMPARATIVE EXAMPLE 3, except that the
silane-based coupling agent was replaced by 16 g of epoxy-modified
silicone oil (manufactured by Shinetsu Chemical Co., Ltd;
KF-101).
[0160] Then, the treatment solution containing the inorganic filler
was incorporated with the cyanate resin solution prepared above and
158 g of methylethylketone, and the mixture was stirred at
65.degree. C. for 1 hour and then cooled. The resultant solution
was incorporated with 0.18 g of zinc naphthenate as a setting
promoter, to prepare the resin varnish containing non-volatile
content at around 65%.
COMPARATIVE EXAMPLE 5
[0161] The cyanate resin solution prepared in the same manner as in
EXAMPLE 9 was incorporated with 1044 g of methylethylketone and
1275 g of the same silica as used in EXAMPLE 9 as the inorganic
filler, and the mixture was stirred at 65.degree. C. for 1 hour and
then cooled. The resultant solution, however, was significantly
thickened at around room temperature, and then solidified into a
grease-like solid. Therefore, it was incorporated further with 1258
g of toluene and stirred into a solution. It was incorporated with
0.05 g of zinc naphthenate as a setting promoter, to prepare the
resin varnish containing non-volatile content at around 41%.
COMPARATIVE EXAMPLE 6
(Preparation of the Cyanate Resin Solution)
[0162] A cyanate resin solution was prepared in the same manner as
in EXAMPLE 9, except that p-tert-butyl phenol was replaced by 22.6
g of 2,2-bis(4-hydroxyphenyl)propane (manufactured by Mitsui
Chemicals, Inc.; bisphenol A). The solution was incorporated with
0.1 g of manganese naphthenate as a reaction promoter, after it was
confirmed to be homogeneous and kept at 110.degree. C., and heated
for 1 hour to synthesize the phenol-modified cyanate oligomer
solution, where the 2,2-bis(4-hydroxyphenyl)propane was converted
at a rate of 41%.
(Preparation of the Inorganic Filler Treated with a Coupling
Agent)
[0163] A treatment solution containing an inorganic filler treated
with a coupling agent was prepared in the same manner as in EXAMPLE
1, except that the solution containing the silicone polymer was
replaced by 22 g of .gamma.-glycidoxypropyltrimethoxysilane as a
silane-based coupling agent.
(Preparation of the Resin Varnish)
[0164] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above and 501
g of methylethylketone, and the mixture was stirred at 65.degree.
C. for 1 hour and then cooled. The resultant solution, however, was
significantly thickened at around room temperature, and then
solidified into a grease-like solid. Therefore, it was incorporated
further with 1382 g of toluene and stirred into a solution. It was
incorporated with 0.05 g of zinc naphthenate as a setting promoter,
to prepare the resin varnish containing non-volatile content at
around 40%.
COMPARATIVE EXAMPLE 7
(Preparation of the Cyanate Resin Solution)
[0165] A cyanate resin solution was prepared in the same manner as
in COMPARATIVE EXAMPLE 6, except that
2,2-bis(4-hydroxyphenyl)propane was replaced by 21 g of phenol
novolac (manufactured by Hitachi Chemical Co., Ltd; HP850N). The
solution was incorporated with 0.1 g of manganese naphthenate as a
reaction promoter, after it was confirmed to be homogeneous and
kept at 110.degree. C., and heated for 1 hour to synthesize the
phenol-modified cyanate oligomer solution, where the
2,2-bis(4-cyanatophenyl)propane was converted at a rate of 41%.
(Preparation of the Inorganic Filler Treated with Epoxy-Modified
Silicone Oil)
[0166] A treatment solution containing an inorganic filler treated
with epoxy-modified silicone oil was prepared in the same manner as
in COMPARATIVE EXAMPLE 2, except that the silane-based coupling
agent was replaced by 22 g of epoxy-modified silicone oil
(manufactured by Shinetsu Chemical Co., Ltd; KF-101).
(Preparation of the Resin Varnish)
[0167] The treatment solution containing the inorganic filler was
incorporated with the cyanate resin solution prepared above and 500
g of methylethylketone, and the mixture was stirred at 65.degree.
C. for 1 hour and then cooled. The resultant solution, however, was
significantly thickened at around room temperature, and then
solidified into a grease-like solid. Therefore, it was incorporated
further with 1509 g of toluene and stirred into a solution. It was
incorporated with 0.05 g of zinc naphthenate as a setting promoter,
to prepare the resin varnish containing non-volatile content at
around 39%.
COMPARATIVE EXAMPLE 8
(Preparation of the Cyanate Resin Solution)
[0168] A cyanate resin solution was prepared by dissolving 400 g of
a commercially available 2,2-bis(4-cyanatephenyl)propane
(manufactured by ASAHI CIBA CORPORATION; Arocy B-30) in 147 g of
toluene, and incorporating the resultant solution with a solution
of 320 g of a polyphenylene ether resin (PKN4752) dissolved in 442
g of toluene under heating at 90.degree. C.
(Preparation of the Resin Varnish)
[0169] The cyanate resin solution was incorporated with 1002 g of
methylethylketone and 1224 g of the same silica as used in EXAMPLE
9, and the mixture was stirred at 65.degree. C. for 1 hour and then
cooled. The resultant solution, however, was significantly
thickened at around room temperature, and then solidified into a
grease-like solid. Therefore, it was incorporated further with 987
g of toluene and stirred into a solution. It was incorporated with
0.15 g of zinc naphthenate as a setting promoter, to prepare the
resin varnish containing non-volatile content at around 43%.
[0170] Next, a 0.2-mm thick glass cloth (E glass) was impregnated
with the resin varnish prepared in each of EXAMPLES 1 to 16 and
COMPARATIVE EXAMPLES 1 to 8, and dried at 160.degree. C. for 5 to
10 minutes to produce the prepreg containing resin solid
(resin+inorganic filler) at 65% by weight. Four sheets of the
resultant prepreg were placed one on another. The resultant
laminate was coated with a 18-.mu.m thick copper foil on each of
the outermost layers, pressed under heating at 170.degree. C. and
3.0 MPa for 60 minutes, and thermally treated at 230.degree. C. for
120 minutes, to prepare the double-sided copper clad laminate. It
was evaluated for its dielectric properties, solder heat
resistance, drill-machinability and resistance to electric
corrosion. The results are given in Tables 1 and 2.
[0171] The double-sided copper clad laminate was evaluated by the
following procedures. Varnish spreadability and prepreg appearances
were evaluated beforehand by visual observation. For spreadability,
a varnish was marked .largecircle., when no inorganic filler was
attached to the roll while it was spread, and others with X even
when it was attached only slightly. For appearance, a prepreg was
marked with .largecircle. when it had surface smoothness on a level
with that of the common prepreg containing no filler, and others
with X.
[0172] Relative dielectric constant (.di-elect cons.r) and
dielectric loss tangent (tan .delta.) at 1 MHz were measured in
accordance with JIS C-6481, and those at 1 GHz by the
triplate-structured straight-line resonator method using a network
analyzer.
[0173] For solder heat resistance, the copper clad laminate with
etched copper foil was held in a pressure cooker tester under
conditions of 121.degree. C. and 203 kPa for 2 hours, and then
immersed in molten solder kept at 260.degree. C. for 20 seconds to
visually observe its outer appearances. "Pass" described in the
tables means no measling or blister was observed.
[0174] Water absorptivity (unit: % by weight) was determined from
the weight difference between the laminate kept under the normal
conditions and that kept under the conditions of 121.degree. C. and
203 kPa for 2 hours in the pressure cooker.
[0175] For drill-machinability, the double-sided copper clad
laminate was bored by a drill (diameter: 0.4 mm) at 80,000 rpm and
feed rate of 2,400 mm/minute, and each of the resultant
through-hole was plated by the normal procedure. It was used as the
base for a cast sample of epoxy resin, and the through-hole was
microscopically observed, to evaluate magnitude of cracking
(average of the 20 holes, unit: .mu.m), caused by delamination or
the like, on the hole walls at the interface between the glass
cloth and resin material.
[0176] For resistance to electric corrosion, the double-sided
copper clad laminate was bored by a drill (diameter: 0.4 mm) at
80,000 rpm and feed rate of 2,400 mm/minute to provide the
through-holes at a pitch of 350 .mu.m. Each through-hole was plated
by the normal procedure to prepare a wiring board with a test
pattern. A voltage of 100V was applied to the test piece thus
prepared kept under conditions of 85.degree. C. and 85% RH, to
measure time before current-caused breakdown was observed.
TABLE-US-00001 TABLE 1 COMPARATIVE EXAMPLES EXAMPLES Items 1 2 3 4
5 6 7 8 1 2 3 4 Spreadability .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. X X X X Prepreg .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. X X X X appearance
.epsilon. .gamma. 1 MHz 3.75 3.63 3.56 3.72 3.70 10.50 3.63 3.75
3.78 3.85 3.86 3.88 1 GHz 3.72 3.60 3.53 3.68 3.66 9.90 3.61 3.72
3.75 3.83 3.83 3.86 tan .delta. 1 MHz 0.0029 0.0027 0.0025 0.0028
0.0028 0.0029 0.0030 0.0029 0.0031 0.0035 0.0036 0.0037 1 GHz
0.0035 0.0034 0.0029 0.0033 0.0034 0.0035 0.0036 0.0035 0.0036
0.0043 0.0043 0.0045 Solder heat Pass Pass Pass Pass Pass Pass Pass
Pass Blis- Blis- Blis- Blis- resistance ter ter ter ter Water 0.32
0.31 0.33 0.31 0.30 0.30 0.29 0.33 0.56 0.62 0.59 0.63 absorptivity
(% by weight) Drill- 25 26 21 25 28 23 25 26 43 45 38 37
machinability (magnitude of cracking, .mu.m) Resistance >500
>500 >500 >500 >500 >500 >500 >500 24 12 24 48
to electric corrosion (hours)
[0177] TABLE-US-00002 TABLE 2 COMPARATIVE EXAMPLES EXAMPLES Items 9
10 11 12 13 14 16 16 5 6 7 8 Spreadability .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. X X X X Prepreg
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. X X X X
appearance .epsilon. .gamma. 1 MHz 3.67 3.56 3.51 3.65 3.62 10.20
3.52 3.67 3.70 3.74 3.74 3.81 1 GHz 3.63 3.53 3.48 3.62 3.61 9.70
3.50 3.64 3.66 3.70 3.72 3.78 tan .delta. 1 MHz 0.0022 0.0020
0.0019 0.0022 0.0022 0.0024 0.0020 0.0022 0.0023 0.0029 0.0031
0.0039 1 GHz 0.0029 0.0027 0.0026 0.0028 0.0030 0.0035 0.0033
0.0029 0.0031 0.0037 0.0040 0.0045 Solder heat Pass Pass Pass Pass
Pass Pass Pass Pass Blis- Blis- Blis- Blis- resistance ter ter ter
ter Water 0.29 0.27 0.26 0.29 0.31 0.32 0.25 0.30 0.53 0.51 0.48
0.55 absorptivity (% by weight) Drill- 23 24 22 21 19 26 24 23 36
42 38 41 machinability (magnitude of cracking, .mu.m) Resistance
>500 >500 >500 >500 >500 >500 >500 >500 12
24 48 12 to electricc corrosion (hours)
[0178] It is apparent, as shown in Tables 1 and 2, that the varnish
prepared in each of EXAMPLES 1 to 16 provided a prepreg which had
good appearances with a smooth surface. By contrast, in the varnish
prepared in each of COMPARATIVE EXAMPLES 1 to 8, the agglomerated
inorganic filler particles were precipitated, and the varnish
provided a defective prepreg with lines on the surface, dripped and
foamed resin, and agglomerated inorganic filler particles.
Moreover, the varnish prepared in each of EXAMPLES 1 to 16
exhibited good workability, no inorganic filler attached to the
roll while the varnish was spread.
[0179] Further, the varnish prepared in each of EXAMPLES 1 to 16
provided a laminate excellent in dielectric properties, and in
particular, low in relative dielectric constant and dielectric loss
tangent at a high-frequency bandwidth (1 GHz), where it should be
noted that the varnish prepared in each of EXAMPLES 6 and 14 was
intended to have a high dielectric constant and low dielectric loss
tangent. In addition, each of the above laminates had a lower water
absorptivity, higher heat resistance while it was absorbing
moisture, better drill-machinability because of lower magnitude of
cracking on the hole walls and higher resistance to electric
corrosion than the one which used the varnish prepared in each of
COMPARATIVE EXAMPLES.
EXAMPLE 17
[0180] A 2-liter four-mouthed separable flask equipped with a
thermometer, cooling tube and stirrer was charged with 231 g of
toluene, 2,2-bis(4-cyanatephenyl)propane and
p-.alpha.-cumyl)phenol. The mixture was then incorporated with zinc
naphthenate as a reaction promoter, after it was kept at
120.degree. C. as liquid temperature, and heated for 4 hours
(reactant concentration: 75% by weight) to synthesize the
phenol-modified cyanate oligomer, where the reaction process was
controlled to have a cyanate compound monomer conversion of about
55%. This conversion was confirmed by liquid chromatography
(Chromatograph: pump; manufactured by Hitachi, Ltd; L-6200, RI
detector; L-3300, and columns, Manufactured by TOSHO CORPORATION,
TSKgel-G4000H and G2000H, solvent: THF, concentration: 1%). The
same chromatograph was used to determine number-average molecular
weight of the product with a calibration curve of the standard
polystyrene. The phenol-modified cyanate ester oligomer had a
number-average molecular weight (Mn) of 1,430 on the cyanate
monomer-free basis. It was also confirmed by the same chromatograph
that the elution peak of p-(.alpha.-cumyl)phenol disappeared.
[0181] The phenol-modified cyanate oligomer was cooled to room
temperature, and incorporated with methylethylketone and the same
zinc naphthenate. The mixture was stirred for 1 hour, to prepare
the varnish containing non-volatile content at 65% and a gelation
time (at 160.degree. C.) of around 300 seconds.
EXAMPLE 18
[0182] A varnish was prepared in the same manner as in EXAMPLE 17,
except that p-(.alpha.-cumyl)phenol was incorporated at a rate
shown in Table 3 in two installments, during the process of
synthesizing the mixed oligomer and after it was cooled.
EXAMPLE 19
[0183] A varnish was prepared in the same manner as in EXAMPLE 17,
except that brominated bisphenol A type epoxy resin (manufactured
by Sumitomo Chemical Company, Ltd; ESB400T) was incorporated at a
rate shown in Table 3 in the synthesized mixed oligomer, after it
was cooled.
EXAMPLE 20
[0184] A varnish was prepared in the same manner as in EXAMPLE 17,
except that 2,2-bis(4-cyanatephenyl)propane was replaced by
bis(3,5-dimethyl-4-cyanatophenyl)methane, which was incorporated at
a rate shown in Table 3.
EXAMPLE 21
[0185] A varnish was prepared in the same manner as in EXAMPLE 17,
except that p-(.alpha.-cumyl)phenol was replaced by p-tert-octyl
phenol, which was incorporated at a rate shown in Table 3.
EXAMPLE 22
[0186] A varnish was prepared in the same manner as in EXAMPLE 19,
except that brominated bisphenol A type epoxy resin was replaced by
a phenol salicylaldehyde novolac type epoxy resin substituted by
methyl and tert-butyl groups (manufactured by Sumitomo Chemical
Company, Ltd; ESB400T), which was incorporated at a rate shown in
Table 3.
COMPARATIVE EXAMPLE 9
[0187] A varnish was prepared in the same manner as in EXAMPLE 17,
except that the synthesized mixed oligomer was replaced by an
oligomer composed of 2,2-bis(4-cyanatephenyl)propane alone
(manufactured by ASAHI CIBA CORPORATION; Arocy B-30) dissolved at
room temperature in toluene at a rate shown in Table 4.
COMPARATIVE EXAMPLE 10
[0188] A varnish was prepared in the same manner as in EXAMPLE 17,
except that p-(.alpha.-cumyl)phenol was replaced by
2,2-bis(4-hydroxyphenyl)propane (bisphenol A), which was
incorporated at a rate shown in Table 4.
COMPARATIVE EXAMPLE 11
[0189] A varnish was prepared by incorporating the varnish prepared
in COMPARATIVE EXAMPLE 9 with phenol novolac (manufactured by
Hitachi-Chemical Co., Ltd; HP850) at room temperature at a rate
shown in Table 4.
COMPARATIVE EXAMPLE 12
[0190] A varnish was prepared by incorporating the varnish prepared
in COMPARATIVE EXAMPLE 9 with brominated bisphenol A type epoxy
resin at room temperature at a rate shown in Table 4.
COMPARATIVE EXAMPLE 13
[0191] A varnish was prepared in the same manner as in COMPARATIVE
EXAMPLE 12, except that brominated bisphenol A type epoxy resin was
replaced by a phenol salicylaldehyde novolac type epoxy resin
substituted by tert-butyl group, which was incorporated at a rate
shown in Table 4.
COMPARATIVE EXAMPLE 14
[0192] A varnish was prepared by incorporating the varnish prepared
in COMPARATIVE EXAMPLE 9 with p-(.alpha.-cumyl)phenol at room
temperature at a rate shown in Table 4.
COMPARATIVE EXAMPLE 15
[0193] A varnish, containing non-volatile content at 55% by weight,
was prepared in the same manner as in EXAMPLE 17, except that
2,2-bis(4-cyanatophenyl)propane and p-.alpha.-cumyl)phenol were
incorporated in a solution of poly(2,6-dimethyl-1,4-phenylene
ether) [number-average molecular weight: around 17,000 and
weight-average molecular weight: around 49,000, both determined by
gel permeation chromatography with a calibration curve of the
standard polystyrene] dissolved in toluene, to synthesize the
phenol-modified cyanate oligomer in the presence of a polyphenylene
ether, and methylethylketone was incorporated in the resultant
ether. TABLE-US-00003 TABLE 3 Compositions Unit: parts by weight
EXAMPLES Items 17 18 19 20 21 22 Cyanate
2,2-Bis(4-cyanatophenyl)propane 300 300 300 -- 300 300 compounds
Bis(3,5-dimethyl-4-cyanatophenyl)methane -- -- -- 300 -- -- Phenol
P-(.alpha.-cumyl)phenol (during the synthesis process) 36 6 36 35
-- 36 compounds P-(.alpha.-cumyl)phenol (after the synthesis
product -- 30 -- -- -- -- was cooled) P-tert-octyl phenol -- -- --
-- 35 -- Zinc naphthenate (during the oligomer synthesis process)
0.2 0.5 0.2 0.2 0.2 0.2 Zinc naphthenate (after the synthesis
product was cooled) 0.4 0.1 0.4 0.4 0.4 0.4 Conversion (%) 55 56 56
54 56 54 Epoxy ESB-400T -- -- 120 -- -- -- resins TMH574 -- -- --
-- -- 75
[0194] TABLE-US-00004 TABLE 4 Compositions Unit: parts by weight
COMPARATIVE EXAMPLES (parts by weight) Items 9 10 11 12 13 14 15
Cyanate 2,2-Bis(4-cyanatophenyl)propane -- 300 -- -- -- -- 300
compounds Acocy B-30 300 -- 300 300 300 300 -- Phenol
P-(.alpha.-cumyl)phenol -- -- -- -- -- 36 36 compounds Bisphenol A
-- 17 -- -- -- -- -- HP850 -- -- 15 -- -- -- -- Polyphenylene ether
-- -- -- -- -- -- 50 Zinc naphthenate (during the oligomer
synthesis process) -- 0.1 -- -- -- -- 0.2 Zinc naphthenate (after
the synthesis product was cooled) 1.0 0.5 0.6 1.0 1.0 0.7 0.4
Conversion (%) -- 55 -- -- -- -- 55 Epoxy ESB-400T -- -- -- 120 --
-- -- resins TMH574 -- -- -- -- 75 -- --
[0195] Viscosity of the varnish prepared in each of EXAMPLES 17 to
22 and COMPARATIVE EXAMPLES 9 to 15 was measured at 25.degree. C.
by an E type viscometer, immediately after it was prepared and
after it was left at 20.degree. C. for 7 days.
[0196] A 0.2-mm thick woven fabric of glass (E glass) was
impregnated with the varnish immediately after it was prepared, and
dried to produce the prepreg which contained the resin at around
41.0% by weight. The appearances of prepregs were visually
observed. The results are given in Tables 5 and 6, where "good"
means that the prepreg had smooth surface showing no lines, or
dripped or foamed resin.
[0197] Four sheets of the resultant prepreg were placed one on to
another. The resultant laminate was coated with a 18-.mu.m thick
copper foil on the outermost layer, pressed under heating at
170.degree. C. and 3.0 MPa for 60 minutes, and thermally treated at
230.degree. C. for 120 minutes, to prepare the copper-clad laminate
having a thickness of around 0.8 mm. It was evaluated for its
dielectric properties, solder heat resistance and
punching-machinability. The results are given in Tables 5 and
6.
[0198] The copper-clad laminate was evaluated by the following
procedures. [0199] Relative dielectric constant (.di-elect cons.r)
and dielectric loss tangent (tan .delta.) at 1 MHz and 1 GHz were
measured in the same manner as in EXAMPLE 1. [0200] Solder heat
resistance: Measured in the same manner as in EXAMPLE 1, except
that the pressure cooker test (PCT) was conducted at 0.22 MPa.
[0201] Prepreg appearance: The laminate with etched copper foil was
treated by a blank and pierce die, and observed for appearances of
the cut-off section. "Good" in Tables 5 and 6 means that there was
no delamination, fuzz, burr or the like. [0202] Copper foil peel
strength: Measured in accordance with JIS C-6481.
[0203] The results are given in Tables 5 and 6. TABLE-US-00005
TABLE 5 Test Results COMPARATIVE EXAMPLES Items 17 18 19 20 21 22
Varnish Immediately after the test 87 71 91 102 84 80 viscosity
piece was prepared (cP, 25? C.) 1 day after the test piece 88 71 90
104 86 78 was prepared 7 days after the test piece 102 92 105 121
105 112 was prepared Prepreg appearance Good Good Good Good Good
Good .epsilon. .gamma. 1 MHz 3.67 3.66 3.74 3.61 3.67 3.76 1 GHz
3.62 3.61 3.69 3.58 3.62 3.75 tan .delta. 1 MHz 0.0025 0.0024
0.0039 0.0022 0.0027 0.0042 1 GHz 0.0055 0.0053 0.0063 0.0048
0.0056 0.0065 Solder heat resistance PCT 1 h 3/3 3/3 3/3 3/3 3/3
3/3 (No. of test pieces showing PCT 2 h 3/3 3/3 3/3 3/3 3/3 3/3 no
abnormality/No. of test PCT 3 h 3/3 3/3 3/3 3/3 3/3 3/3 pieces
tested) PCT 4 h 3/3 3/3 3/3 3/3 3/3 3/3 PCT 5 h 3/3 3/3 3/3 3/3 3/3
3/3 Copper clad peel strength (kN/m) 1.60 1.60 1.56 1.57 1.60 1.58
Machinability Good Good Good Good Good Good
[0204] TABLE-US-00006 TABLE 6 Test Results COMPARATIVE EXAMPLES
Items 9 10 11 12 13 14 15 Varnish Immediately after the test 83 345
675 78 83 76 80 viscosity piece was prepared (cP, 25.degree. C.) 1
day after the test piece 84 Gelled Gelled 89 90 81 84 was prepared
7 days after the test piece 105 -- -- 118 120 98 95 was prepared
Prepreg appearance Good Good Foaming Good Good Good Foaming/ lines
.epsilon. .gamma. 1 MHz 3.79 3.86 3.95 3.84 3.86 3.68 3.63 1 GHz
3.76 3.83 3.91 3.77 3.80 3.67 3.57 tan .delta. 1 MHz 0.0065 0.0066
0.0072 0.0067 0.0064 0.0029 0.0025 1 GHz 0.0095 0.0098 0.0115
0.0123 0.0115 0.0058 0.0050 Solder heat resistance PCT 1 h 3/3 0/3
0/3 3/3 3/3 3/3 3/3 (No. of test pieces showing PCT 2 h 2/3 0/3 0/3
3/3 3/3 3/3 3/3 no abnormality/No. of test PCT 3 h 1/3 0/3 0/3 1/3
1/3 3/3 3/3 pieces tested) PCT 4 h 0/3 0/3 0/3 0/3 0/3 2/3 3/3 PCT
5 h 0/3 0/3 0/3 0/3 0/3 0/3 1/3 Copper clad peel strength (kN/m)
1.60 1.10 1.07 1.54 1.57 1.57 1.60 Machinability Good Fuzz/ Fuzz/
Good Good Good Good burr burr
[0205] As shown in Table 5, the varnish prepared in each of
EXAMPLES 17 to 22 exhibited good storage stability. Each of these
varnishes provide a copper-clad laminate good in heat resistance
while it was absorbing moisture and machinability. Moreover, each
of these copper-clad laminates had slightly higher heat resistance
while it was absorbing moisture than the one which used the varnish
prepared in COMPARATIVE EXAMPLE 6. Further, each of the prepregs
which used the varnish prepared in each of EXAMPLES 17 to 22 had
smother surface and hence had better appearances than the one which
used the varnish prepared in COMPARATIVE EXAMPLE 15.
[0206] By contrast, the varnish prepared in each of COMPARATIVE
EXAMPLES 10 and 11, incorporated with a polyvalent phenol, was
highly viscous immediately after it was prepared, and had a very
short pot life as to be gelled when stored for only 1 day.
Moreover, the varnish prepared in each of COMPARATIVE EXAMPLES 9 to
13 gave the copper-clad laminate higher both in relative dielectric
constant and dielectric loss tangent than the one which used the
varnish prepared in each EXAMPLE, more notably higher in dielectric
loss tangent at 1 GHz. Still more, the varnish prepared in each of
COMPARATIVE EXAMPLES 10 and 11 gave the copper-clad laminate lower
both in heat resistance while it was absorbing moisture and peel
strength of the copper foil than the one which used the varnish
prepared in each EXAMPLE.
POSSIBILITY OF INDUSTRIAL UTILIZATION
[0207] According to the present invention, the varnish has
excellent dielectric properties, provides a laminate as formable
and machinable as the conventional laminate of a thermosetting
resin, e.g., epoxy resin, and provides a laminate and
printed-wiring board high in heat resistance and excellent in
dielectric properties.
* * * * *