U.S. patent application number 10/582558 was filed with the patent office on 2007-05-24 for polymer composite formed article, printed wiring board using the formed article, and methods of producing them.
Invention is credited to Hisashi Aoki, Miyuki Harada, Tsukasa Ishigaki, Toru Kimura, Mitsukazu Ochi, Naoyuki Shimoyama, Masayuki Tobita.
Application Number | 20070116938 10/582558 |
Document ID | / |
Family ID | 34918292 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070116938 |
Kind Code |
A1 |
Tobita; Masayuki ; et
al. |
May 24, 2007 |
Polymer composite formed article, printed wiring board using the
formed article, and methods of producing them
Abstract
A thermoplastic polymer composite formed article or a
thermoplastic polymer composite formed article formed from a
thermoplastic polymer or a thermoplastic polymer and a fiber,
wherein the fiber is arranged along a first plane and the molecular
chains of the thermoplastic polymer or thermoplastic polymer is
oriented in the direction intersecting with the first plane, and
the molecular chains of the thermoplastic polymer or thermoplastic
polymer has a degree (a) of orientation in a range of 0.5 or more
and less than 1.0, and wherein the thermal expansion coefficients
of said formed article in the direction along the first plane and
in the direction intersecting with the first plane are both
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K), and the difference
between the thermal expansion coefficient in the direction along
the first plane and the thermal expansion coefficient in the
direction intersecting with the first plane is 30.times.10.sup.-6
(/K) or less.
Inventors: |
Tobita; Masayuki;
(Isesaki-shi, JP) ; Kimura; Toru; (Funabashi-shi,
JP) ; Aoki; Hisashi; (Tokyo, JP) ; Shimoyama;
Naoyuki; (Saitama-shi, JP) ; Ishigaki; Tsukasa;
(Saitama-shi, JP) ; Ochi; Mitsukazu; (Osaka,
JP) ; Harada; Miyuki; (Osaka, JP) |
Correspondence
Address: |
CROMPTON, SEAGER & TUFTE, LLC
1221 NICOLLET AVENUE
SUITE 800
MINNEAPOLIS
MN
55403-2420
US
|
Family ID: |
34918292 |
Appl. No.: |
10/582558 |
Filed: |
February 18, 2005 |
PCT Filed: |
February 18, 2005 |
PCT NO: |
PCT/JP05/02643 |
371 Date: |
June 12, 2006 |
Current U.S.
Class: |
428/292.1 |
Current CPC
Class: |
B32B 15/08 20130101;
B32B 27/04 20130101; C08G 59/5033 20130101; B32B 15/092 20130101;
H05K 2201/0141 20130101; B32B 2457/08 20130101; B32B 15/20
20130101; B32B 2250/03 20130101; C08J 5/24 20130101; C08K 7/02
20130101; B32B 2274/00 20130101; H05K 2201/0287 20130101; H05K
2201/029 20130101; B32B 2307/206 20130101; C08G 59/28 20130101;
Y10T 428/249924 20150401; H05K 1/0366 20130101; B32B 2250/40
20130101; B32B 27/38 20130101; C08J 2363/00 20130101; B32B 2307/202
20130101; B32B 27/18 20130101; H05K 2201/0129 20130101; H05K
2201/068 20130101; C08K 7/02 20130101; C08L 63/00 20130101 |
Class at
Publication: |
428/292.1 |
International
Class: |
D04H 13/00 20060101
D04H013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2004 |
JP |
2004-066021 |
Claims
1. An epoxy resin composite formed article composed of an epoxy
resin and fibers, wherein the fibers are arranged along a first
plane and molecular chains of the epoxy resin are oriented in a
direction intersecting with the first plane therein, and that
wherein a degree of orientation .alpha. of the molecular chains of
the epoxy resin is in a range of 0.5 or more and less than 1, as
determined by the following expression (1) based on X-ray
diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. at a fixed peak scatter angle in the X-ray diffraction
measurement, and wherein each of the thermal expansion coefficients
of the epoxy resin composite formed article in the direction along
the first plane and in the direction intersecting with the first
plane is in a range of 5.times.10.sup.-6 to 50.times.10.sup.-6 (/K)
and a difference between the thermal expansion coefficients in the
direction along the first plane and in the direction intersecting
with the first plane is 30.times.10.sup.-6 (/K) or less.
2. The epoxy resin composite formed article according to claim 1,
wherein the epoxy resin is a liquid crystalline epoxy resin having
a mesogen group in its molecular.
3. The epoxy resin composite formed article according to claim 1,
wherein the fibers comprise at least one of a fiber cloth and
single fibers.
4. The epoxy resin composite formed article according to claim 1,
wherein the fibers consist of at least one selected from glass
fibers, ceramic fibers, carbon fibers, metal fibers, and organic
fibers.
5. A printed wiring board comprising: an epoxy resin composite
formed article composed of an epoxy resin and fibers, wherein the
fibers are arranged along a first plane and molecular chains of the
epoxy resin are oriented in a direction intersecting with the first
plane therein, wherein a degree of orientation .alpha. of the
molecular chains of the epoxy resin is in a range of 0.5 or more
and less than 1, as determined by the following expression (1)
based on X-ray diffraction measurement, Degree of orientation
.alpha.=(180-.alpha..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. at a fixed peak scatter angle in the X-ray diffraction
measurement, and wherein each of the thermal expansion coefficients
of the epoxy resin composite formed article in the direction along
the first plane and in the direction intersecting with the first
plane is in a range of 5.times.10.sup.-6 to 50.times.10.sup.-6 (/K)
and a difference between the thermal expansion coefficients in the
direction along the first plane and in the direction intersecting
with the first plane is 30.times.10.sup.-6 (/K) or less, and an
electrically conductive layer provided on at least one of a surface
and inside of the epoxy resin composite formed article.
6. A method for producing the epoxy resin composite formed article
composed of an epoxy resin and fibers, wherein the fibers are
arranged along a first plane and molecular chains of the epoxy
resin are oriented in a direction intersecting with the first plane
therein, wherein a degree of orientation .alpha. of the molecular
chains of the epoxy resin is in a range of 0.5 or more and less
than 1, as determined by the following expression (1) based on
X-ray diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. at a fixed peak scatter angle in the X-ray diffraction
measurement, and wherein each of the thermal expansion coefficients
of the epoxy resin composite formed article in the direction along
the first plane and in the direction intersecting with the first
plane is in a range of 5.times.10.sup.-6 to 50.times.10.sup.-6 (/K)
and a difference between the thermal expansion coefficients in the
direction along the first plane and in the direction intersecting
with the first plane is 30.times.10.sup.-6 (/K) or less, said
method comprising the steps of: disposing the fibers within a
cavity of a mold in such a manner that the fibers are arranged
along the first plane, impregnating the fibers with an epoxy resin
composition by filling the cavity of the mold with the epoxy resin
composition, orienting molecular chains of the epoxy resin in a
direction intersecting with the first plane, and curing the epoxy
resin composition while the orientation of the molecular chains of
the epoxy resin is maintained.
7. The method according to claim 6, wherein in the step of
orienting the molecular chains of the epoxy resin, the orientation
of the molecular chains of the epoxy resin is accomplished by
application of a magnetic field thereto.
8. A method for producing the printed wiring board including an
epoxy resin composite formed article composed of an epoxy resin and
fibers, wherein the fibers are arranged along a first plane and
molecular chains of the epoxy resin are oriented in a direction
intersecting with the first plane therein, wherein a degree of
orientation .alpha. of the molecular chains of the epoxy resin is
in a range of 0.5 or more and less than 1, as determined by the
following expression (1) based on X-ray diffraction measurement,
Degree of orientation .alpha.=(180-.DELTA..beta./180) (1) wherein
.DELTA..beta. represents a full width at half maximum in an
intensity distribution measured in an azimuth angle direction from
0 to 360.degree. at a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the epoxy resin composite formed article in the
direction along the first plane and in the direction intersecting
with the first plane is in a range of 5.times.10.sup.-6 to
50.times.10.sup.-6 (/K) and a difference between the thermal
expansion coefficients in the direction along the first plane and
in the direction intersecting with the first plane is
30.times.10.sup.-6 (/K) or less; and an electrically conductive
layer provided on at least one of a surface and inside of the epoxy
resin composite formed article, said method comprising the steps
of: disposing the fibers within a cavity of a mold in such a manner
that the fibers are arranged along the first plane, impregnating
the fibers with an epoxy resin composition by filling the cavity of
the mold with the epoxy resin composition, orienting molecular
chains of the epoxy resin in a direction intersecting with the
first plane, curing the epoxy resin composition while the
orientation of the molecular chains of the epoxy resin is
maintained, and providing an electrically conductive layer on at
least one of a surface and inside of the printed wiring board at
least either prior to the step of disposing, or after the steps of
impregnating, or curing.
9. The method according to claim 8, wherein in the step of
orienting, the orientation of the molecular chains of the epoxy
resin is accomplished by application of a magnetic field
thereto.
10. A method for producing the epoxy resin composite formed article
composed of an epoxy resin and fibers, wherein the fibers are
arranged along a first plane and molecular chains of the epoxy
resin are oriented in a direction intersecting with the first plane
therein, wherein a degree of orientation .alpha. of the molecular
chains of the epoxy resin is in a range of 0.5 or more and less
than 1, as determined by the following expression (1) based on
X-ray diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. at a fixed peak scatter angle in the X-ray diffraction
measurement, and wherein each of the thermal expansion coefficients
of the epoxy resin composite formed article in the direction along
the first plane and in the direction intersecting with the first
plane is in a range of 5.times.10.sup.-6 to 50.times.10.sup.-6 (/K)
and a difference between the thermal expansion coefficients in the
direction along the first plane and in the direction intersecting
with the first plane is 30.times.10.sup.-6 (/K) or less, said
method comprising the steps of: preparing an epoxy resin
composition containing the fibers, filing a cavity of a mold with
the epoxy resin composition in such a manner that a major axis of
each of the fibers are arranged along the first plane, orienting
molecular chains of the epoxy resin in a direction intersecting
with the first plane, and curing the epoxy resin composition, while
the orientation of the molecular chains of the epoxy resin is
maintained.
11. A thermoplastic polymer composite formed article composed of a
thermoplastic polymer and fibers, wherein the fibers are arranged
along a first plane and molecular chains of the thermoplastic
polymer are oriented in a direction intersecting with the first
plane therein, wherein a degree of orientation .alpha. of the
molecular chains of the thermoplastic polymer is in a range of 0.5
or more and less than 1, as determined by the following expression
(1) based on X-ray diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less.
12. The thermoplastic polymer composite formed article according to
claim 11, wherein the thermoplastic polymer is a liquid crystalline
polymer having a mesogen group in its molecular.
13. The thermoplastic polymer composite formed article according to
claims 12, wherein the liquid crystalline polymer is at least one
selected from aromatic polyester, aromatic polyamide, and aromatic
polyesteramide.
14. The thermoplastic polymer composite formed article according to
claim 11, wherein the fibers comprise at least one of a fiber cloth
and single fibers.
15. The thermoplastic polymer composite formed article according to
claim 11, wherein the fibers consist of at least one selected from
glass fibers, ceramic fibers, carbon fibers, metal fibers, and
organic fibers.
16. A printed wiring board formed of the thermoplastic polymer
composite formed article comprising: a thermoplastic polymer
composite formed article composed of a thermoplastic polymer and
fibers, wherein the fibers are arranged along a first plane and
molecular chains of the thermoplastic polymer are oriented in a
direction intersecting with the first plane therein, wherein a
degree of orientation .alpha. of the molecular chains of the
thermoplastic polymer is in a range of 0.5 or more and less than 1,
as determined by the following expression (1) based on X-ray
diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less; and an electrically
conductive layer is provided on at least one of a surface and
inside of the thermoplastic polymer composite formed article.
17. A method for producing the thermoplastic polymer composite
formed article composed of a thermoplastic polymer and fibers,
wherein the fibers are arranged along a first plane and molecular
chains of the thermoplastic polymer are oriented in a direction
intersecting with the first plane therein, wherein a degree of
orientation .alpha. of the molecular chains of the thermoplastic
polymer is in a range of 0.5 or more and less than 1. as determined
by the following expression (1) based on X-ray diffraction
measurement, Degree of orientation .alpha.=(180-.DELTA..beta./180)
(1) wherein .DELTA..beta. represents a full width at half maximum
in an intensity distribution measured in an azimuth angle direction
from 0 to 360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less, said method comprising
the steps of: disposing the fibers within a cavity of a mold in
such a manner that the fibers are arranged along the first plane,
impregnating the fibers with a thermoplastic polymer composition by
filling the cavity of the mold with the thermoplastic polymer
composition, orienting molecular chains of the thermoplastic
polymer in a direction intersecting with the first plane, and
solidifying the thermoplastic polymer composition while the
orientation of the molecular chains of the thermoplastic polymer is
maintained.
18. A method for producing the thermoplastic polymer composite
formed article composed of a thermoplastic polymer and fibers,
wherein the fibers are arranged along a first plane and molecular
chains of the thermoplastic polymer are oriented in a direction
intersecting with the first plane therein, wherein a degree of
orientation .alpha. of the molecular chains of the thermoplastic
polymer is in a range of 0.5 or more and less than 1, as determined
by the following expression (1) based on X-ray diffraction
measurement, Degree of orientation .alpha.=(180-.DELTA..beta./180)
(1) wherein .DELTA..beta. represents a full width at half maximum
in an intensity distribution measured in an azimuth angle direction
from 0 to 360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less, said method comprising
the steps of: forming a preform of a thermoplastic polymer
composition containing the thermoplastic polymer, disposing the
preform and the fibers within a cavity of a mold in such a manner
the preform and the fibers are arranged along the first plane,
impregnating the fibers with a thermoplastic polymer composition by
melting the preform, orienting molecular chains of the
thermoplastic polymer in a direction intersecting with the first
plane, and solidifying the thermoplastic polymer composition while
the orientation of the molecular chains of the thermoplastic
polymer is maintained.
19. A method for producing the thermoplastic polymer composite
formed article composed of a thermoplastic polymer and fibers,
wherein the fibers are arranged along a first plane and molecular
chains of the thermoplastic polymer are oriented in a direction
intersecting with the first plane therein, wherein a degree of
orientation .alpha. of the molecular chains of the thermoplastic
polymer is in a range of 0.5 or more and less than 1, as determined
by the following expression (1) based on X-ray diffraction
measurement, Degree of orientation .alpha.=(180-.DELTA..beta./180)
(1) wherein .DELTA..beta. represents a full width at half maximum
in an intensity distribution measured in an azimuth angle direction
from 0 to 360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less, said method comprising
the steps of: preparing a thermoplastic polymer composition
containing the thermoplastic polymer and the fibers, filing a
cavity of a mold with the thermoplastic polymer composition in such
a manner that a major axis of each of the fibers are arranged along
the first plane, orienting molecular chains of the thermoplastic
polymer in a direction intersecting with the first plane, and
solidifying the thermoplastic polymer composition, while the
orientation of the molecular chains of the thermoplastic polymer is
maintained.
20. The method according to claim 17, wherein in the step of
orienting the molecular chains of the thermoplastic polymer in the
direction intersecting with the first plane, the orientation of the
molecular chains of the thermoplastic polymer is accomplished by
application of a magnetic field thereto.
21. A method for producing the printed wiring board including a
thermoplastic polymer composite formed article composed of a
thermoplastic polymer and fibers, wherein the fibers are arranged
along a first plane and molecular chains of the thermoplastic
polymer are oriented in a direction intersecting with the first
plane therein, wherein a degree of orientation .alpha. of the
molecular chains of the thermoplastic polymer is in a range of 0.5
or more and less than 1, as determined by the following expression
(1) based on X-ray diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less; and an electrically
conductive layer provided on at least one of a surface and inside
of the thermoplastic polymer composite formed article, said method
comprising the steps of: disposing the fibers within a cavity of a
mold in such a manner that the fibers are arranged along the first
plane, impregnating the fibers with a thermoplastic polymer
composition by filling the cavity of the mold with the
thermoplastic polymer composition, orienting molecular chains of
the thermoplastic polymer in a direction intersecting with the
first plane, solidifying the thermoplastic polymer composition
while the orientation of the molecular chains of the thermoplastic
polymer is maintained, and providing an electrically conductive
layer on at least one of a surface and inside of the printed wiring
board at least either prior to the step of disposing, or after the
steps of impregnating, or solidifying.
22. A method for producing the printed wiring board including a
thermoplastic polymer composite formed article composed of a
thermoplastic polymer and fibers, wherein the fibers are arranged
along a first plane and molecular chains of the thermoplastic
polymer are oriented in a direction intersecting with the first
plane therein, wherein a degree of orientation .alpha. of the
molecular chains of the thermoplastic polymer is in a range of 0.5
or more and less than 1, as determined by the following expression
(1) based on X-ray diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less, and an electrically
conductive layer provided on at least one of a surface and inside
of the thermoplastic polymer composite formed article, said method
comprising the steps of: forming a preform of a thermoplastic
polymer composition containing the thermoplastic polymer, disposing
the preform and the fibers within a cavity of a mold in such a
manner the preform and the fibers are arranged along the first
plane, impregnating the fibers with an thermoplastic polymer
composition by melting the preform, orienting molecular chains of
the thermoplastic polymer in a direction intersecting with the
first plane, solidifying the thermoplastic polymer composition
while the orientation of the molecular chains of the thermoplastic
polymer is maintained, and providing an electrically conductive
layer on at least one of a surface and inside of the printed wiring
board at least either prior to the step of disposing, or after the
steps of impregnating, or solidifying.
23. A method for producing the printed wiring board according to
claim 16, including a thermoplastic polymer composite formed
article composed of a thermoplastic polymer and fibers, wherein the
fibers are arranged along a first plane and molecular chains of the
thermoplastic polymer are oriented in a direction intersecting with
the first plane therein, wherein a degree of orientation .alpha. of
the molecular chains of the thermoplastic polymer is in a range of
0.5 or more and less than 1, as determined by the following
expression (1) based on X-ray diffraction measurement, Degree of
orientation .alpha.=(180-.DELTA..beta./180) (1) wherein
.DELTA..beta. represents a full width at half maximum in an
intensity distribution measured in an azimuth angle direction from
0 to 360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the thermoplastic polymer composite formed article
in the direction along to the first plane and in the direction
intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less: and an electrically
conductive layer provided on at least one of a surface and inside
of the thermoplastic polymer composite formed article, said method
comprising the steps of: preparing a thermoplastic polymer
composition containing the thermoplastic polymer and the fibers,
filing a cavity of a mold with the thermoplastic polymer
composition in such a manner that a major axis of each of the
fibers are arranged along the first plane, orienting molecular
chains of the thermoplastic polymer in a direction intersecting
with the first plane, and solidifying the thermoplastic polymer
composition, while the orientation of the molecular chains of the
thermoplastic polymer is maintained, and providing an electrically
conductive layer on at least one of a surface and inside of the
printed wiring board at least either prior to the step of
disposing, or after the steps of impregnating, or solidifying.
24. The method according to claim 21, wherein in the step of
orienting the molecular chains of the thermoplastic polymer in the
direction intersecting with the first plane, the orientation of the
molecular chains of the thermoplastic polymer is accomplished by
application of a magnetic field thereto.
25. A polymer composite formed article composed of a polymer and
fibers, wherein the fibers are arranged along a first plane and
molecular chains of the polymer are oriented in a direction
intersecting with the first plane therein, and that wherein a
degree of orientation .alpha. of the molecular chains of the
polymer is in a range of 0.5 or more and less than 1, as determined
by the following expression (1) based on X-ray diffraction
measurement, Degree of orientation .alpha.=(180-.DELTA..beta./180)
(1) wherein .DELTA..beta. represents a full width at half maximum
in an intensity distribution measured in an azimuth angle direction
from 0 to 360.degree. with a fixed peak scatter angle in the X-ray
diffraction measurement, and wherein each of the thermal expansion
coefficients of the polymer composite formed article in the
direction along the first plane and in the direction intersecting
with the first plane is in a range of 5.times.10.sup.-6 to
50.times.10.sup.-6 (/K) and a difference between the thermal
expansion coefficients in the direction along the first plane and
in the direction intersecting with the first plane is
30.times.10.sup.-6 (/K) or less.
26. The method according to claim 18, wherein in the step of
orienting the molecular chains of the thermoplastic polymer in the
direction intersecting with the first plane, the orientation of the
molecular chains of the thermoplastic polymer is accomplished by
application of a magnetic field thereto.
27. The method according to claim 19, wherein in the step of
orienting the molecular chains of the thermoplastic polymer in the
direction intersecting with the first plane, the orientation of the
molecular chains of the thermoplastic polymer is accomplished by
application of a magnetic field thereto.
28. The method according to claim 22, wherein in the step of
orienting the molecular chains of the thermoplastic polymer in the
direction intersecting with the first plane, the orientation of the
molecular chains of the thermoplastic polymer is accomplished by
application of a magnetic field thereto.
29. The method according to claim 23, wherein in the step of
orienting the molecular chains of the thermoplastic polymer in the
direction intersecting with the first plane, the orientation of the
molecular chains of the thermoplastic polymer is accomplished by
application of a magnetic field thereto.
Description
TECHNICAL FIELD
[0001] The present invention generally relates to a polymer
composite formed article having thermal expansion coefficients
controlled to be isotropically reduced in both a direction
extending along the surface of the formed article and a direction
intersecting with said direction and a printed wiring board using
the formed article. More specifically, the present invention
relates to an epoxy resin composite formed article and a
thermoplastic polymer composite formed article each having thermal
expansion coefficients controlled to be isotropically reduced in
both a direction extending along the surface of the formed article
and a direction intersecting with said direction. The present
invention also relates to printed wiring boards produced using the
epoxy resin composite formed article and the thermoplastic polymer
composite formed article.
BACKGROUND ART
[0002] Conventionally, polymer composite material formed articles
in which functional fibers such as a glass fiber, a carbon fiber, a
metal fiber, an aramid fiber, or a polybenzazole fiber are
incorporated into a polymer material as a matrix have been widely
known.
[0003] Meanwhile, polymer compositions including an epoxy resin, or
a thermoplastic resin have been generally used as insulating
materials for printed wiring boards, and electronic parts such as
semiconductor packages to be implemented on the printed wiring
boards. In addition to polymer materials such as an epoxy resin and
a thermoplastic polymer, various dissimilar materials such as metal
and ceramics have been used for those printed wiring boards and
electronic parts. Those various dissimilar materials may be joined
or arranged to be adjacent to each other in a wiring board or an
electronic part. Therefore, when the temperature of the environment
surrounding these wiring board or the electronic part changes, a
difference in thermal expansion coefficients between the dissimilar
materials may causes thermal stress in the wiring board, the
electronic part itself, or at an interface between the dissimilar
materials thereon. In particular, there is a large difference in
thermal expansion coefficients between a polymer material such as
an epoxy resin or a thermoplastic polymer for forming a wiring
board (a general thermal expansion coefficient at room temperature:
>5.times.10.sup.-5 (/K) and a metal such as copper to be used
for a wiring material. (a thermal expansion coefficient at room
temperature: 1.65.times.10.sup.-5 (/K)). Therefore, a wiring board
or an electronic part composed of a polymer material such as an
epoxy resin and a metal may have problems including a cracking,
peeling at an interface between a polymer material portion (e.g.,
epoxy resin) and a metal portion, and breakage or shorting of the
wiring due to thermal stress generated.
[0004] To cope with the above-mentioned problems, a copper-clad
laminate has been generally used as a printed wiring board. Such
copper-clad laminate is formed by integrally molding a prepreg and
copper foil under heat and pressure, and drying the resultant. The
prepreg is obtained by impregnating a base material such as glass
cloth with a polymer composition containing an epoxy resin, a
thermoplastic polymer, or the like. Furthermore, Japanese Laid-Open
Patent Publications No. 2002-53646, No. 2001-288251, and No.
10-145020 each disclose an epoxy resin composition having a reduced
thermal expansion coefficient to reduce the thermal expansion
coefficient of a substrate material. Japanese Laid-Open Patent
Publications No. 11-147960 and No. 08-255959 each disclose a
substrate including a special base material and reinforcing
material. Japanese Laid-Open Patent Publications No. 10-034742
discloses a liquid crystal polymer laminated body used as a
substrate material for a flexible printed wiring board or the like.
The laminated body includes an isotropic liquid crystal polymer
which has low thermal expansivity and which is oriented at random
in a plane to reduce the anisotropy of a thermal expansion
coefficient in the plane of the substrate. In addition, substrates
blended with a filler having low expansivity such as silica have
been proposed.
[0005] With the advent of the increase in number of layers, and
complication, of printed wiring boards in recent years, it has
become important to suppress thermal expansion, particularly in the
thickness direction of a printed wiring board for the purpose of,
for example, securing through-hole reliability of the boards. In
each of such glass cloth-impregnated epoxy printed wiring boards
and epoxy printed wiring boards including a special base material
and reinforcing material as above-described, thermal expansion in a
direction extending along the surface of the printed wiring board
can be reduced. However, in contrast, thermal expansion in the
thickness direction of the boards increases.
[0006] In an epoxy printed wiring board using an epoxy resin
composition having a reduced thermal expansion coefficient or an
epoxy printed wiring board blended with a filler having low
expansivity such as silica, the thermal expansion of the wiring
board can be isotropically reduced to some extent, but the
reduction is insufficient. For example, Japanese Laid-Open Patent
Publication No. 2004-175995 discloses a film in which a composition
including a blend of a liquid crystal polymer and another
thermoplastic polymer is used to reduce the thermal expansion
coefficient in the thickness direction.
[0007] In an epoxy formed article in which molecular chains of a
liquid crystalline epoxy resin are oriented in a specific direction
by applying magnetic fields to the resin, thermal expansion in the
orientation direction can be reduced, but thermal expansion in any
other direction increases.
[0008] Therefore, a polymer formed article such as an epoxy resin
formed article in which thermal expansion is isotropically reduced
in each of a direction extending along the surface of the formed
article and a direction perpendicular to the said direction has
been strongly demanded.
[0009] The present invention has been made to address such problems
as above-described. An objective of the present invention is to
provide a polymer composite formed article such as an epoxy resin
composite formed article in which thermal expansion is
isotropically reduced in each of a direction extending along the
surface of the formed article and a direction intersecting with
said direction and a printed wiring board formed of such polymer
composite formed article. Another objective of the present
invention is to provide a method of producing the polymer composite
formed article such as an epoxy resin composite formed article and
a method of producing the printed wiring board formed of the
polymer composite formed article.
DISCLOSURE OF THE INVENTION
[0010] To address to the problems above, one aspect of the present
invention provides an epoxy resin composite formed article composed
of an epoxy resin and fibers. In the formed article, the fibers are
arranged along a first plane and molecular chains of the epoxy
resin are oriented in a direction intersecting with the first
plane. A degree of orientation .alpha. of the molecular chains of
the epoxy resin is in a range of 0.5 or more and less than 1, as
determined by the following expression (1) based on X-ray
diffraction measurement: Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1)
[0011] wherein .DELTA..beta. represents a full width at half
maximum in an intensity distribution measured in an azimuth angle
direction from 0 to 360.degree. at a fixed peak scatter angle in
the X-ray diffraction measurement. Each of the thermal expansion
coefficients of the epoxy resin composite formed article in the
direction along the first plane and in the direction intersecting
with the first plane is in a range of 5.times.10.sup.-6 to
50.times.10.sup.-6 (/K) and a difference between the thermal
expansion coefficients in the direction along the first plane and
in the direction intersecting with the first plane is
30.times.10.sup.-6 (/K) or less. In this case, the thermal
expansion coefficients can be controlled to be isotropically small,
thereby reducing any damages such as cracks due to thermal
expansion.
[0012] The epoxy resin is preferably a liquid crystalline epoxy
resin having a mesogenic group in its molecular.
[0013] The fibers preferably comprise at least one of a fiber cloth
and single fibers.
[0014] The fibers preferably consist of at least one selected from
glass fibers, ceramic fibers, carbon fibers, metal fibers, and
organic fibers.
[0015] In another aspect, a printed wiring board formed of the
epoxy resin composite formed article is provided, wherein an
electrically conductive layer is provided on at least one of a
surface and inside of the epoxy resin composite formed article.
[0016] In still another aspect, a method for producing the epoxy
resin composite formed article is provided. The method includes
disposing the fibers within a cavity of a mold in such a manner
that the fibers are arranged along the first plane, impregnating
the fibers with an epoxy resin composition by filling the cavity of
the mold with the epoxy resin composition, orienting molecular
chains of the epoxy resin in a direction intersecting with the
first plane, and curing the epoxy resin composition while the
orientation of the molecular chains of the epoxy resin is
maintained. According to this method, the epoxy resin composite
formed article in which the thermal expansion coefficients are
controlled to be isotropically small can be obtained easily.
[0017] In the step of orienting the molecular chains of the epoxy
resin, the orientation of the molecular chains of the epoxy resin
is preferably accomplished by application of a magnetic field
thereto.
[0018] In another aspect, a method for producing the printed wiring
board is also provided. The method includes disposing the fibers
within a cavity of a mold in such a manner that the fibers are
arranged along the first plane, impregnating the fibers with an
epoxy resin composition by filling the cavity of the mold with the
epoxy resin composition, orienting molecular chains of the epoxy
resin in a direction intersecting with the first plane, curing the
epoxy resin composition while the orientation of the molecular
chains of the epoxy resin is maintained, and providing an
electrically conductive layer on at least one of a surface and
inside of the printed wiring board at least either prior to the
step of disposing, or after the steps of impregnating, or curing.
According to this method, the printed wiring board in which the
thermal expansion coefficients are controlled to be isotropically
small can be easily obtained.
[0019] In the step of orienting, the orientation of the molecular
chains of the epoxy resin is preferably accomplished by application
of a magnetic field thereto.
[0020] In still another aspect, an alternative method for producing
the epoxy resin composite formed article. This method includes
preparing an epoxy resin composition containing the fibers, filing
a cavity of a mold with the epoxy resin composition in such a
manner that a major axis of each of the fibers are arranged along
the first plane, orienting molecular chains of the epoxy resin in a
direction intersecting with the first plane, and curing the epoxy
resin composition, while the orientation of the molecular chains of
the epoxy resin is maintained. According this method, the epoxy
resin formed article in which the thermal expansion coefficients
are controlled to be isotropically small can be easily
obtained.
[0021] In another aspect, a thermoplastic polymer composite formed
article composed of a thermoplastic polymer and fibers. In the
formed article, the fibers are arranged along a first plane and
molecular chains of the thermoplastic polymer are oriented in a
direction intersecting with the first plane.
[0022] The degree of orientation .alpha. of the molecular chains of
the thermoplastic polymer is in a range of 0.5 or more and less
than 1, as determined by the following expression (1) based on
X-ray diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1)
[0023] wherein .DELTA..beta. represents a full width at half
maximum in an intensity distribution measured in an azimuth angle
direction from 0 to 360.degree. at a fixed peak scatter angle in
the X-ray diffraction measurement.
[0024] Each of the thermal expansion coefficients of the
thermoplastic polymer composite formed article in the direction
along the first plane and in the direction intersecting with the
first plane is in a range of 5.times.10.sup.-6 to
50.times.10.sup.-6 (/K) and the difference between the thermal
expansion coefficients in the direction along the first plane and
in the direction intersecting with the first plane is
30.times.10.sup.-6 (/K) or less. In this case, the thermal
expansion coefficients can be controlled to be isotropically small,
thereby reducing any damage such as cracks due to thermal
expansion.
[0025] The thermoplastic polymer is preferably a liquid crystalline
polymer having a mesogenic group in its molecular.
[0026] The liquid crystalline polymer is preferably at least one
selected from aromatic polyester, aromatic polyamide, and aromatic
polyesteramide.
[0027] The fibers preferably comprise at least one of a fiber cloth
and single fibers.
[0028] The fibers preferably consist of at least one selected from
glass fibers, ceramic fibers, carbon fibers, metal fibers, and
organic fibers.
[0029] In an another aspect, a printed wiring board formed of the
thermoplastic polymer composite formed article is provided, wherein
an electrically conductive layer is provided on at least one of a
surface and inside of the thermoplastic polymer composite formed
article.
[0030] In still another aspect, a method for producing the
thermoplastic polymer composite formed article is provided. This
method includes disposing the fibers within a cavity of a mold in
such a manner that the fibers are arranged along the first plane,
impregnating the fibers with an thermoplastic polymer composition
by filling the cavity of the mold with the thermoplastic polymer
composition, orienting molecular chains of the thermoplastic
polymer in a direction intersecting with the first plane, and
solidifying the thermoplastic polymer composition while the
orientation of the molecular chains of the thermoplastic polymer is
maintained.
[0031] In another aspect, an alternative method for producing the
thermoplastic polymer composite formed article is provided. This
method includes forming a preform of a thermoplastic polymer
composition containing the thermoplastic polymer, disposing the
preform and the fibers within a cavity of a mold in such a manner
the preform and the fibers are arranged along the first plane,
impregnating the fibers with an thermoplastic polymer composition
by melting the preform, orienting molecular chains of the
thermoplastic polymer in a direction intersecting with the first
plane, and solidifying the thermoplastic polymer composition while
the orientation of the molecular chains of the thermoplastic
polymer is maintained.
[0032] In another aspect, an alternative method for producing the
thermoplastic polymer composite formed article is provided. This
method includes preparing an thermoplastic polymer composition
containing the thermoplastic polymer and the fibers, filing a
cavity of a mold with the thermoplastic polymer composition in such
a manner that a major axis of each of the fibers is arranged along
the first plane, orienting molecular chains of the thermoplastic
polymer in a direction intersecting with the first plane, and
solidifying the thermoplastic polymer composition, while the
orientation of the molecular chains of the thermoplastic polymer is
maintained. According to these methods, a thermoplastic polymer
composite formed article in which the thermal expansion
coefficients are controlled to be isotropically small can be easily
obtained.
[0033] In the step of orienting the molecular chains of the
thermoplastic polymer in the direction intersecting with the first
plane, the orientation of the molecular chains of the thermoplastic
polymer is preferably accomplished by application of a magnetic
field thereto.
[0034] In another aspect, a method for producing the printed wiring
board is provided. This method includes disposing the fibers within
a cavity of a mold in such a manner that the fibers are arranged
along the first plane, impregnating the fibers with an
thermoplastic polymer composition by filling the cavity of the mold
with the thermoplastic polymer composition, orienting molecular
chains of the thermoplastic polymer in a direction intersecting
with the first plane, solidifying the thermoplastic polymer
composition while the orientation of the molecular chains of the
thermoplastic polymer is maintained, and providing an electrically
conductive layer on at least one of a surface and inside of the
printed wiring board at least either prior to the step of
disposing, or after the steps of impregnating, or solidifying.
[0035] In still another aspect, an alternative method for producing
the printed wiring board is provided. This method includes forming
a preform of a thermoplastic polymer composition containing the
thermoplastic polymer, disposing the preform and the fibers within
a cavity of a mold in such a manner the preform and the fibers are
arranged along the first plane, impregnating the fibers with an
thermoplastic polymer composition by melting the preform, orienting
molecular chains of the thermoplastic polymer in a direction
intersecting with the first plane, solidifying the thermoplastic
polymer composition while the orientation of the molecular chains
of the thermoplastic polymer is maintained, and providing an
electrically conductive layer on at least one of a surface and
inside of the printed wiring board at least either prior to the
step of disposing, or after the steps of impregnating, or
solidifying.
[0036] In another aspect, an alternative method for producing the
printed wiring board is provided. This method includes preparing a
thermoplastic polymer composition containing the thermoplastic
polymer and the fibers, filing a cavity of a mold with the
thermoplastic polymer composition in such a manner that a major
axis of each of the fibers are arranged along the first plane,
orienting molecular chains of the thermoplastic polymer in a
direction intersecting with the first plane, solidifying the
thermoplastic polymer composition, while the orientation of the
molecular chains of the thermoplastic polymer is maintained, and
providing an electrically conductive layer on at least one of a
surface and inside of the printed wiring board at least either
prior to the step of disposing, or after the steps of impregnating,
or solidifying. According to these methods, a printed wiring board
in which thermal expansion coefficients are controlled to be
isotropically small can be easily obtained.
[0037] In the step of orienting the molecular chains of the
thermoplastic polymer in the direction intersecting with the first
plane, the orientation of the molecular chains of the thermoplastic
polymer is accomplished by application of a magnetic field
thereto.
[0038] In another aspect, a polymer composite formed article
composed of a polymer and fibers is provided. In this formed
article, the fibers are arranged along a first plane and molecular
chains of the polymer are oriented in a direction intersecting with
the first plane.
[0039] The degree of orientation .alpha. of the molecular chains of
the polymer is in a range of 0.5 or more and less than 1, as
determined by the following expression (1) based on X-ray
diffraction measurement, Degree of orientation
.alpha.=(180-.DELTA..beta./180) (1)
[0040] wherein .DELTA..beta. represents a full width at half
maximum in an intensity distribution measured in an azimuth angle
direction from 0 to 360.degree. at a fixed peak scatter angle in
the X-ray diffraction measurement.
[0041] Each of the thermal expansion coefficients of the polymer
composite formed article in the direction along the first plane and
in the direction intersecting with the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K) and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction intersecting with the first
plane is 30.times.10.sup.-6 (/K) or less. In this case, the thermal
expansion coefficients are controlled to be isotropically small,
thereby reducing any damages such as cracks due to thermal
expansion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1 is a perspective view showing an epoxy resin
composite formed article of a first embodiment and a thermoplastic
polymer composite formed article of a third embodiment.
[0043] FIG. 2 is a sectional view showing the epoxy resin composite
formed article of the first embodiment.
[0044] FIG. 3 is a sectional view showing a printed wiring board of
a second embodiment.
[0045] FIG. 4 is an X-ray diffraction pattern showing an X-ray
diffraction intensity distribution in the radial direction of a
debye ring of an epoxy resin composition component of the epoxy
resin composite formed article.
[0046] FIG. 5 is a graph showing an intensity distribution in the
azimuth angle direction of the epoxy resin composition component of
the epoxy resin composite formed article.
[0047] FIG. 6 is a schematic view showing a method of producing the
epoxy resin composite formed article of the first embodiment.
[0048] FIG. 7 is a schematic view showing the method of producing
the epoxy resin composite formed article of the first
embodiment.
[0049] FIG. 8 is a schematic view showing the method of producing
the epoxy resin composite formed article of the first
embodiment.
[0050] FIG. 9 is a schematic view showing a method of producing the
printed wiring board of the second embodiment.
[0051] FIG. 10 is a schematic view showing the method of producing
the printed wiring board of the second embodiment.
[0052] FIG. 11 is a sectional view showing the thermoplastic
polymer composite formed article of the third embodiment.
[0053] FIG. 12 is a sectional view showing a printed wiring board
of a fourth embodiment.
[0054] FIG. 13 is a schematic view showing a method of producing
the thermoplastic polymer composite formed article of the third
embodiment.
[0055] FIG. 14 is a schematic view showing the method of producing
the thermoplastic polymer composite formed article of the third
embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0056] Hereinafter, the best mode for carrying out the present
invention will be described in detail.
[0057] The present invention provides a polymer composite formed
article composed of a polymer and fibers. In the polymer composite
formed article, the fibers are arranged along a first plane, and
the molecular chains of the polymer are oriented in a direction
intersecting with the first plane, whereby a thermal expansion
coefficient is reduced in each direction.
First Embodiment
[0058] With reference to FIGS. 1 and 2, an epoxy resin composite
formed article 1 according to a first embodiment of the present
invention will be described. The epoxy resin composite formed
article 1 has a plate-like shape, and is formed of an epoxy resin
composition 16 and a plurality of fiber cloths 15. In the epoxy
resin composite formed article 1, each fiber cloth 15 is a cloth
constructed from a great number of single fibers. Each fiber cloth
15 is arranged in the epoxy resin composition 16 to be parallel
with a first plane, that is, a surface of the formed article 1. In
the epoxy resin composite formed article 1 of this embodiment, the
molecular chains of an epoxy resin in the epoxy resin composition
16 are oriented in the direction perpendicular to the first plane,
namely, in the thickness direction (Z direction in FIG. 1) of the
formed article 1. In other words, the molecular chains of the epoxy
resin are arranged to be perpendicular to each fiber cloth 15.
[0059] In this embodiment, discrete single fibers may be used in
addition to or as an alternative to the fiber cloths 15.
[0060] In this case, for example, the single fibers are oriented in
such a manner that each fiber axis of the single fibers is parallel
to the surface of the epoxy resin composite formed article 1 (for
example, the X and Y directions of FIG. 1) and preferably directed
in a random direction respectively, while the molecular chains of
the epoxy resin are oriented in the thickness direction of the
formed article 1 (the Z direction of FIG. 1).
Second Embodiment
[0061] With reference to FIG. 3, a printed wiring board 2 according
to a second embodiment of the present invention embodied using the
epoxy resin composite formed article 1 will be described. The
printed wiring board 2 includes an epoxy resin composite formed
article 1 formed in the same manner as in the first embodiment and
conductive layers 14a and 14b formed on the upper and lower
surfaces of the formed article 1 so as to sandwich the formed
article 1 therebetween. In the epoxy resin composite formed article
1, the fiber cloths 15 are arranged to be parallel with the surface
of the wiring board 2. In the epoxy resin composite formed article
1, the molecular chains of the epoxy resin are oriented in the
direction perpendicular to the surface of the wiring board 2, that
is, in the thickness direction of the wiring board 2.
[0062] In this embodiment as well, single fibers may be used in
addition to or as an alternative to the fiber cloths 15. In this
case, as in the case of the first embodiment, the single fibers are
oriented in such a manner that each fiber axis is parallel to the
surface of the epoxy resin composite formed article 1 (for example,
the X and Y directions of FIG. 1) and preferably, directed in a
random direction respectively, while the molecular chains of the
epoxy resin are oriented in the thickness direction of the formed
article 1 (the Z direction of FIG. 1).
Third Embodiment
[0063] With reference to FIGS. 1 and 11, a thermoplastic polymer
composite formed article 10 according to a third embodiment of the
present invention will be described. The thermoplastic polymer
composite formed article 10 has a plate-like shape. The formed
article 10 is formed of a thermoplastic polymer composition 160 and
a plurality of fiber cloths 15. In the thermoplastic polymer
composite formed article 10, each fiber cloth 15 is a cloth
composed of a great number of single fibers. Each fiber cloth 15 is
arranged in the thermoplastic polymer composition 160 to be
parallel with a first plane, that is, the surface of the formed
article 10 in this embodiment. In the thermoplastic polymer
composite formed article 10, the molecular chains of a
thermoplastic polymer in the thermoplastic polymer composition 160
are oriented in the direction perpendicular to the first plane,
i.e., in the thickness direction of the formed article (the Z
direction of FIG. 1) in this embodiment. In other words, the
molecular chains of the thermoplastic polymer are arranged to be
perpendicular to each fiber cloth 15.
[0064] In this embodiment, discrete single fibers may be used in
addition to or as an alternative to the fiber cloths 15.
[0065] In this case, for example, the single fibers are oriented in
such a manner that each fiber axis is parallel to the surface of
the thermoplastic polymer composite formed article 10 and
preferably, directed in a random direction respectively, while the
molecular chains of the thermoplastic polymer are oriented in the
thickness direction of the formed article 10 (the Z direction of
FIG. 1).
Fourth Embodiment
[0066] With reference to FIG. 12, a printed wiring board 20
according to a fourth embodiment of the present invention embodied
using the thermoplastic polymer composite formed article 10 will be
described. The printed wiring board 20 includes the thermoplastic
polymer composite formed article 10 formed in the same manner as in
the first embodiment and the conductive layers 14a and 14b formed
on the upper and lower surfaces of the formed article 10 so as to
sandwich the formed article 10 between them. In the thermoplastic
polymer composite formed article 10, the fiber cloths 15 are
arranged parallel to the surface of the wiring board 20. In the
thermoplastic polymer composite formed article 10, the molecular
chains of the thermoplastic polymer is oriented in the direction
perpendicular to the surface of the wiring board 20, i.e. in the
thickness direction of the wiring board 20.
[0067] In this embodiment, discrete single fibers may be also used
in addition to or as an alternative to the fiber cloths 15. In this
case, as in the case of the third embodiment, the single fibers are
oriented in such a manner that each fiber axis is in parallel with
the surface of the thermoplastic polymer composite formed article
10 and preferably, directed in a random direction respectively,
while the molecular chains of the thermoplastic polymer are
oriented in the thickness direction of the formed article 10 (the Z
direction of FIG. 1).
[0068] In each of the second and fourth embodiments, the printed
wiring board requires high electrical insulating property in an
insulator portion thereof. Therefore, the fiber cloths and the
single fibers arranged in the epoxy resin composite formed article
1 and the thermoplastic polymer composite formed article 10 are
preferably insulative. A layer capable of forming an electrical
circuit such as metal foil, a metal-plated layer, or a conductive
paste layer can be used for each of the conductive layers 14a and
14b.
[0069] In the epoxy resin composite formed article 1 and the
thermoplastic polymer composite formed article 10 of the first to
fourth embodiments, the degree of orientation .alpha. of the
molecular chains of the epoxy resin or the thermoplastic polymer is
in a range of 0.5 or more and less than 1.0. The degree of
orientation .alpha. is determined by the following expression (1)
based on the X-ray diffraction measurement. Degree of orientation
.alpha.=(180-.DELTA..beta./180 . . . (1) wherein .DELTA..beta.
represents a full width at half maximum in an intensity
distribution measured in an azimuth angle direction from 0 to
360.degree. at a fixed peak scatter angle in the X-ray diffraction
measurement.
[0070] In order to determine the degree of orientation .alpha., the
epoxy resin composite formed article 1 or the thermoplastic polymer
composite formed article 10 is subjected to wide-angle X-ray
diffraction measurement (transmission). When a sample is irradiated
with an X-ray in an X-ray diffraction instrument, a concentric
arc-like diffraction pattern (debye ring) is obtained if any
particles (molecular chains) in the sample are oriented. Firstly, a
diffraction pattern showing an X-ray diffraction intensity
distribution in the radial direction from the center of such debye
ring is obtained for the sample of the formed article (see FIG. 4).
In this diffraction pattern, the axis of abscissa indicates an
angle 2.theta. twice as large as the diffraction angle .theta. of
an X-ray. A peak observed at the position of 2.theta.=20.degree. is
considered to show a distance between molecular chains of a solid
epoxy resin or thermoplastic polymer.
[0071] The angle at which the diffraction peak of the epoxy resin
or the thermoplastic resin (peak scatter angle) appears is
generally around 20.degree., although the angle may range from
about 15.degree. to 30.degree. depending on a difference in
structure of the epoxy resin or the thermoplastic resin or on a
difference in constituents of the epoxy resin composition or the
thermoplastic resin composition. An X-ray diffraction intensity
distribution in the azimuth angle direction (the circumferential
direction of the debye ring) from 0.degree. to 360.degree. is
measured, while the measurement angle in the radial direction is
fixed at the angle (peak scatter angle) at which the diffraction
peak occurs. Thereby, such an X-ray diffraction intensity
distribution in the azimuth angle direction at the peak scatter
angle as shown in FIG. 5 can be obtained. A sharper peak in the
intensity distribution means that the molecular chains of the epoxy
resin or the thermoplastic resin are more highly oriented in a
fixed direction. Therefore, a width of the peak at half height
(full width at half maximum .DELTA..beta.) is determined in the
intensity distribution in the azimuth angle direction. Then, the
full width at half maximum .DELTA..beta. is substituted into the
expression (1). Thereby, the degree of orientation .alpha. of the
molecular chain of the epoxy resin or the thermoplastic polymer can
be calculated. The degree of orientation .alpha. is 0.72 in the
case of the intensity distribution in the azimuth angle direction
shown in FIG. 5.
[0072] To obtain an effect as expected from the present invention
with improved efficiency, the value for the degree of orientation a
is in a range of 0.5 or more and less than 1.0, preferably 0.55 or
more and less than 1.0, more preferably 0.6 or more and less than
1.0, or still more preferably 0.7 or more and less than 1.0.
However, a range for the degree of orientation a varies depending
on the extent to which a thermal expansion coefficient must be
reduced. In an epoxy resin composite formed article and a
thermoplastic polymer composite formed article, the degree of
orientation .alpha. of the molecular chains of each of an epoxy
resin and a thermoplastic polymer within the above ranges can
significantly reduce the thermal expansion coefficient in the
orientation direction of each formed article.
[0073] When the degree of orientation .alpha. in each of the epoxy
resin composite formed article and the thermoplastic polymer
composite formed article of the present invention is less than 0.5,
the thermal expansion coefficient of each of the formed articles is
not reduced enough to obtain sufficient effects. Meanwhile, the
degree of orientation .alpha. cannot be equal to or more than 1.0
in the expression (1) because the full width at half maximum
.DELTA..beta. always has a positive value.
[0074] Each of the thermal expansion coefficients of the epoxy
resin composite formed article 1 and the thermoplastic polymer
composite formed article 10 in the direction parallel to the first
plane, namely, the surface of the formed articles 1, 10 and in the
direction perpendicular to the first plane is in a range of
5.times.10.sup.-6 to 50.times.10.sup.-6 (/K), or more preferably
10.times.10.sup.-6 to 40.times.10.sup.-6 (/K), and a difference
between the thermal expansion coefficients in the direction along
the first plane and in the direction perpendicular to the first
plane is 30.times.10.sup.-6 (/K) or less.
[0075] In the epoxy resin composite formed article 1 or the
thermoplastic polymer composite formed article 10, the fiber cloths
15 (or the single fibers) are arranged to be parallel to the
surface of the formed article (the first plane), and the molecular
chains of the epoxy resin or the thermoplastic polymer are oriented
in the direction perpendicular to the surface of the formed
article, i.e. the thickness direction of the formed article. The
molecular chains of the epoxy resin or the thermoplastic polymer as
a matrix of the formed article 1 or 10 are oriented in the
direction intersecting with the fiber cloths 15 (or the single
fibers) in this way. Thereby, thermal expansion can be reduced in
both the direction in which the fiber cloths 15 (or the single
fibers) extend (i.e. the direction along the surface) and the
direction intersecting with said direction in which the molecular
chains of the epoxy resin or the thermoplastic polymer extend (i.e.
the thickness direction). In addition, the molecular chains of the
epoxy resin or the thermoplastic polymer are extremely small as
compared to the fibers constructing the fiber cloths 15 or gaps
between the fibers, so the orientation of the molecular chains is
hardly inhibited by the fiber cloths 15 (or single fibers).
Accordingly, the fiber cloths 15 (or single fibers) can be
incorporated at a high density into the formed article.
[0076] The epoxy resin composite formed article 1 and the
thermoplastic polymer composite formed article 10 are applicable to
insulating materials for various composite materials, printed
wiring boards, semiconductor packages, casings, and the like. As a
result, in the various electronic parts, problems due to a
difference in thermal expansion between the epoxy resin or the
thermoplastic polymer material and any other material including
cracks, peeling of an interface, and breakage or short of circuit
wirings, and reductions in properties of the electronic parts in
association with the problems can be reduced.
[0077] In addition, the printed wiring boards 2 and 20 in the
second and fourth embodiments are each characterized in that the
conductive layers 14a and 14b are formed on both surfaces of the
epoxy resin composite formed article 1 or the thermoplastic polymer
composite formed article 10 as an insulator to form the boards 2,
20. Each of the printed wiring boards 2 and 20 can reduce problems
due to a difference in thermal expansion between each of the
conductive layers 14a, 14b and the insulator (the epoxy resin
composite formed article 1 or the thermoplastic polymer composite
formed article 10) such as cracks, peeling of an interface, and
breakage and short of circuit wirings, and reductions in properties
in association with the problems, and can improve through-hole
stability.
[0078] Hereinafter, the respective constituents of the epoxy resin
composite formed article 1 and the thermoplastic polymer composite
formed article 10 of the present invention will be described in
detail.
<Epoxy Resin>
[0079] Examples of an epoxy resin used in an epoxy resin
composition include a bisphenol type, a novolac type, a naphthalene
type, a triphenol alkane type, a biphenyl type, a cyclic aliphatic
epoxy resins, and halides or hydrides thereof. Each of those epoxy
resins may be used alone, or two or more of them may be used in
combination. Furthermore, among of those epoxy resins, a liquid
crystalline epoxy resin having a mesogenic group in a molecule is
particularly preferably used for the epoxy resin composite formed
article. Liquid crystallinity of the liquid crystalline epoxy resin
having a mesogenic group can facilitate to orient the molecular
chains of the epoxy resin, and control the degree of orientation of
the epoxy resin. The content of the liquid crystalline epoxy resin
having a mesogenic group in a molecule in the total epoxy resins
contained in the epoxy resin composition is preferably, but not
particularly limited to, 50 wt % or more.
[0080] A liquid crystalline epoxy resin having a mesogenic group in
the main chain of the molecule is a particularly preferable. The
term "mesogenic group" refers to a functional group capable of
exhibiting liquid crystallinity. Specific examples of the group
include biphenyl, cyanobiphenyl, terphenyl, cyanoterphenyl, phenyl
benzoate, azobenzene, azomethine, azoxybenzene, stilbene, phenyl
cyclohexyl, biphenyl cyclohexyl, phenoxyphenyl, benzylideneaniline,
benzyl benzoate, bipyridine, phenyl pyrimidine, phenyl dioxane,
benzoyl aniline, tolan, and derivatives thereof.
[0081] The number of mesogenic groups in a molecular chain of an
epoxy resin is at least one, and may be two or more. The liquid
crystalline epoxy resin may also include a soft structure portion
called a bent chain (spacer), which is composed of, for example, an
aliphatic hydrocarbon group, an aliphatic ether group, an aliphatic
ester group, a siloxane bond between the mesogenic groups.
[0082] Such liquid crystalline epoxy resin exhibits a liquid
crystal state in a certain temperature range, and has a property
that some of the mesogenic groups tend to be regularly arranged.
The liquid crystallinity can be confirmed by exhibition of strong
birefringence inherent in a liquid crystal obtained in an ordinary
polarization test using an orthogonal polarizer. The liquid
crystalline epoxy resin may exhibit any kind of the liquid crystal
states including nematic, smectic, cholesteric, and discotic
states. The liquid crystalline epoxy resin having a mesogenic group
and another epoxy resin containing no mesogenic group may be mixed
for use.
<Thermoplastic Polymer>
[0083] A liquid crystal thermoplastic polymer having a mesogenic
group in a molecule is preferably used as a thermoplastic polymer
in a thermoplastic polymer composition. The liquid crystallinity of
the liquid crystal thermoplastic polymer having a mesogenic group
in a molecule can facilitate orientation of the molecular chains of
the thermoplastic polymer and control the degree of orientation of
the thermoplastic polymer. The content of the liquid crystal
thermoplastic polymer having a mesogenic group in a total amount of
the thermoplastic polymers contained in the composition is
preferably, but not particularly limited to, 50 wt % or more.
[0084] A liquid crystal polymer having a mesogenic group in the
main chain of a molecule (a main chain type liquid crystal polymer)
is a particularly preferable for use. The term "mesogenic group"
refers to a functional group capable of exhibiting liquid
crystallinity. Specific examples of the group include biphenyl,
cyanobiphenyl, terphenyl, cyanoterphenyl, phenyl benzoate,
azobenzene, azomethine, azoxybenzene, stilbene, phenyl cyclohexyl,
biphenyl cyclohexyl, phenoxyphenyl, benzylideneaniline, benzyl
benzoate, bipyridine, phenyl pyrimidine, phenyl dioxane, benzoyl
aniline, tolan, and derivatives thereof.
[0085] The number of mesogenic groups in a molecular chain of the
liquid crystal thermoplastic polymer is at least one, and may be
two or more. The liquid crystal thermoplastic polymer also may
include a soft structure portion called a bent chain (spacer),
which is composed of, for example an aliphatic hydrocarbon group,
an aliphatic ether group, an aliphatic ester group, and a siloxane
bond, between mesogenic groups.
[0086] A thermal liquid crystal polymer is a specific example of
the liquid crystal thermoplastic polymer.
[0087] The term of "thermal liquid crystal polymer" refers to a
liquid crystal polymer which has thermoplasticity and which
exhibits a liquid crystal state showing optical anisotropy within a
predetermined temperature range when melted by heating. Examples of
the thermal liquid crystal polymer include polyester, polyamide,
polyesteramide, polyether ketone, polycarbonate, and polyimide.
Each of those polymers may be used alone, or two or more of them
may be used in combination.
[0088] Such liquid crystal thermoplastic polymer is in a liquid
crystal state in a predetermined temperature range, and has a
property that some of the mesogenic groups tend to be regularly
arranged. The liquid crystallinity can be confirmed by exhibition
of strong birefringence inherent in a liquid crystal obtained in an
ordinary polarization test using an orthogonal polarizer. The
liquid crystal thermoplastic polymer may exhibit any kind of the
liquid crystal states including nematic, smectic, cholesteric, and
discotic states. A liquid crystal thermoplastic polymer having a
mesogenic group in a molecule and a thermoplastic polymer
containing no mesogenic group in a molecule may be mixed and
used.
<Fiber>
[0089] The fibers to be used for the epoxy resin composite formed
article 1 and the thermoplastic polymer composite formed article 10
of the present invention are a fiber cloth or an aggregation of
discrete single fibers (simply referred to as "single fibers") The
fiber length and fiber diameter of a single fiber in a fiber cloth
or group of single fibers to be used, and the weave density of
fibers in a fiber cloth are not particularly limited. However, in
consideration of the productivity, handling, and ease of blending
into an epoxy resin composition and a thermoplastic polymer
composition of a single fiber, the diameter of a single fiber is
practically preferably 0.1 to 30 .mu.m, and the weave density of
fibers in a fiber cloth is preferably about 5 to 50 fibers/25 mm
for each of a weft and a warp. Each of fibers in a fiber cloth may
be woven to be spaced apart from each other in such a manner that
the fiber cloth can be easily impregnated with the epoxy resin
composition and the thermoplastic polymer composition. A ratio
between the numbers of warps and wefts to be knitted may be
appropriately adjusted. In addition, the fiber cloth may be a woven
or non-woven fabric obtained by fixing fibers with a polymer resin,
such as a felt cloth. Although the kinds of single fibers
constituting the fiber cloth and the aggregation of single fibers
are not particularly limited, at least one selected from glass
fibers, carbon fibers, metal fibers, ceramic fibers, and organic
fibers is preferable.
[0090] When the value for the anisotropic diamagnetic
susceptibility .chi..sub.a of a fiber is large, the fiber receives
a large force in a direction parallel with or perpendicular to a
line of magnetic force in a magnetic field. The anisotropic
diamagnetic susceptibility .chi..sub.a is a value showing the
anisotropy of a diamagnetic susceptibility generated by applying an
external magnetic field, the value being obtained by subtracting a
susceptibility .chi..sup..perp. in the direction perpendicular to
the fiber axis of the fiber from a susceptibility .chi.'' in the
direction of the fiber axis. A fiber in which the anisotropic
diamagnetic susceptibility .chi..sub.a has a positive value such as
a carbon fiber, an aramid fiber, or a polybenzazole fiber receives
a force such that each fiber axis is aligned parallel to lines of
magnetic force M in a magnetic field. The molecular chains of a
main chain type liquid crystalline epoxy resin and a main chain
type liquid crystal thermoplastic polymer also receives a force
such that their axes are aligned parallel to the lines of magnetic
force M in a magnetic field. As a result, these molecular chains
are oriented in the direction parallel to the lines of the magnetic
force.
[0091] As described above, the molecular chains of an epoxy resin
and a thermoplastic polymer also tends to be oriented parallel to
lines of magnetic force M. Therefore, when fibers having the
anisotropic diamagnetic susceptibility .chi..sub.a in a positive
value are used and the molecular chains of an epoxy resin or a
thermoplastic polymer are oriented by a magnetic field, attention
must be paid to prevent the fibers from being oriented by the
magnetic field in the same direction as the orientation direction
of the molecular chains of the epoxy resin or the thermoplastic
polymer. Examples of a method for the prevention include use of
fibers hardly oriented by a magnetic field, that is, fibers in
which the anisotropic diamagnetic susceptibility .chi..sub.a itself
is small; long fibers, aggregated and assembled fibers, or fibers
having a high specific gravity that require larger force to be
oriented; and the use of an epoxy resin composition or
thermoplastic polymer composition having high viscosity.
[0092] In addition, a fiber cloth and single fibers may be used in
combination. Furthermore, two or more kinds of fiber cloths or
single fibers may be used together. As long as at least one kind of
fiber cloth or single fibers among the fiber cloths and the single
fibers are arranged in a direction intersecting with the
orientation direction of the molecular chains of the epoxy resin or
the thermoplastic polymer, the other fiber cloths or single fibers
may not be oriented, or may be arranged in the same direction as
the orientation direction of the molecular chains of the epoxy
resin or the thermoplastic polymer.
<Epoxy Resin Composition>
[0093] The epoxy resin composition 16 for forming the epoxy resin
composite formed article 1 contains epoxy resin as above-described,
and arbitrarily at least one of a fiber cloth and a set of single
fibers. The epoxy resin composition may be added with a curing
agent for the purpose of curing the epoxy resin through any
reaction. The kind and amount of curing agent to be added as well
as conditions for heat curing, photo-curing, and moisture curing
are not particularly limited. For example, ordinary amine-based
curing agents, acid anhydride-based curing agents, phenol-based
curing agents, latent curing agents, polymercaptan-based curing
agents, polyaminoamide-based curing agents, isocyanates, block
isocyanate, or the like can be used. Each of those curing agents
may be used alone, or two or more of them may be used as a mixture.
The content of each of those curing agents is typically the same as
the amount of the curing agent to be used.
[0094] Epoxy groups of the epoxy resin may be self-polymerized
without blending of any curing agent. In this case, a
polymerization initiator is added to the epoxy resin
composition.
[0095] The epoxy resin to be used in the present invention can be
polymerized through a cationic polymerization using any one of
acids such as AlCl.sub.3, SnCl.sub.4, TiCl.sub.4, BF.sub.3,
PCl.sub.5, SbF.sub.5 and salts thereof as a polymerization
initiator. Similarly, the epoxy resin can be polymerized through an
anionic polymerization using an ammonium salt such as tetrabutyl
ammonium bromide or dimethyl dibenzyl ammonium chloride as a
polymerization initiator.
[0096] The epoxy resin composition may contain a small amount of
another reaction curable resin in addition to the epoxy resin.
<Thermoplastic Polymer Composition>
[0097] The thermoplastic polymer composition 160 for forming the
thermoplastic polymer composite formed article 10 contains the
thermoplastic polymer as above-described. Furthermore, the
thermoplastic polymer composition 160 may contain at least one of a
fiber cloth and a set of single fibers.
[0098] Each of the epoxy resin composition and the thermoplastic
polymer composition can be blended with an appropriate amount of a
filler for additionally reducing the expansion coefficient of each
epoxy resin composite formed article and the thermoplastic polymer
composite formed article and for improving various properties such
as fracture toughness, flexural strength, dielectric constant, and
thermal conductivity. Examples of the fillers include metals, metal
oxides, metal nitrides, metal carbides, metal hydroxides, metal
carbonate compounds, metal-coated resins, resin fillers, carbon
fibers, glass fibers, glass beads, carbon-based materials, talc,
and clay. Examples of the metals include silver, copper, gold,
platinum, and zircon. Examples of the metal oxides include silicon
oxide, aluminum oxide, and magnesium oxide. Examples of the metal
nitrides include boron nitride, aluminum nitride, and silicon
nitride. An example of the metal carbides includes silicon carbide.
Examples of the metal hydroxides include aluminum hydroxide and
magnesium hydroxide. The filler may be subjected to a treatment
with a typical coupling agent for the purposes of improving
wettability between the epoxy resin or the thermoplastic polymer
and the filler, reinforcing the interface between the epoxy resin
or the thermoplastic polymer and the filler, and promoting the
dispersion of the fillers into the epoxy resin or the thermoplastic
polymer.
[0099] It should be noted that each of the epoxy resin composition
and the thermoplastic polymer composition can be added with a
curing accelerator, a curing retardant, a reinforcement, a
stress-lowering agent such as rubbers or elastomers, a pigment, a
dye, a fluorescent bleach, a dispersant, a stabilizer, a UV
absorber, an energy quencher, an antistatic agent, an antioxidant,
a thermal stabilizer, a lubricant, a flame retardant, a defoaming
agent, a plasticizer, a solvent, or the like, as required.
[0100] Next, the methods for producing the epoxy resin composite
formed article 1, the thermoplastic polymer composite formed
article 10, and the printed wiring boards 2, 20 will be
described.
[0101] The epoxy resin composite formed article 1 is formed by:
arranging the fiber cloths 15 along a first plane (for example, the
surface of the formed article 1) in the epoxy resin composition 16;
and curing the epoxy resin composition 16 in a state where the
molecular chains of an epoxy resin in the composition 16 are
oriented in the direction intersecting with the first plane (for
example, the thickness direction of the formed article 1).
[0102] The thermoplastic polymer composite formed article 10 is
formed by: arranging the fiber cloths 15 along a first plane (for
example, the surface of the formed article 10) in the thermoplastic
polymer composition 160; and solidifying the thermoplastic polymer
composition 160 in a state where the molecular chains of a
thermoplastic polymer in the composition 160 are oriented in the
direction intersecting with the first plane (for example, the
thickness direction of the formed article 10).
[0103] A device capable of molding an epoxy resin and a
thermoplastic polymer such as a transfer molding device, a press
molding device, a cast molding device, an injection molding device,
or an extrusion molding device can be used as a molding device. The
epoxy resin composition 16 and the thermoplastic polymer
composition 160 can be molded into an epoxy resin composite formed
article and a thermoplastic polymer composite formed article in any
one of various shapes including a sheet, a film, a block, a
granular shape, a rod, a tubular, and a fibrous shape.
[0104] An example of a method of orienting the molecular chains of
each of the epoxy resin and the thermoplastic polymer in the
compositions 16 and 160 includes a method involving orienting the
molecular chains by means of at least one selected from rubbing,
stretching, rolling, a flow field, a shear field, a magnetic field,
and an electric field prior to or upon curing/solidification of the
compositions. Of those orientation methods, an orientation method
by means of a magnetic field is preferable because the direction in
which the molecular chains of the epoxy resin and the thermoplastic
polymer are oriented can be easily controlled. The application of a
magnetic field to the epoxy resin or the thermoplastic polymer
causes their molecular chains to be oriented parallel to lines of
magnetic force M. Some of the orientation processes above-described
can be used together as required.
[0105] Examples of a magnetic field generator device for generating
a magnetic field include a permanent magnet, an electromagnet, a
superconducting magnet, and a coil. Of those magnetic field
generators, a superconducting magnet is preferable because it can
generate a magnetic field having a practical magnetic flux
density.
[0106] The magnetic flux density of a magnetic field to be applied
to the epoxy resin composition is preferably 0.2 to 20 tesla (T),
more preferably 0.5 to 15 T, or most preferably 1 to 10 T. A
magnetic flux density of less than 0.2 T cannot sufficiently orient
the rigid molecular chains of an epoxy resin, resulting in an
insufficient reduction in thermal expansion coefficient. On the
other hand, a magnetic field having a magnetic flux density in
excess of 20 T is hardly obtained in practical use. A magnetic flux
density in a range of 0.2 to 20 T provides an epoxy resin composite
formed article having a low thermal expansion coefficient and is
practical.
[0107] The magnetic flux density of a magnetic field to be applied
to the thermoplastic polymer composition is preferably 1 to 20
tesla (T), more preferably 2 to 15 T, or most preferably 3 to 10 T.
A magnetic flux density of less than 1 T cannot sufficiently orient
the molecular chains of a thermoplastic polymer, resulting in an
insufficient reduction in thermal expansion coefficient. On the
other hand, a magnetic field having a magnetic flux density in
excess of 20 T is hardly obtained in practical use. A magnetic flux
density in a range of 1 to 20 T provides a thermoplastic polymer
composite formed article having a low thermal expansion coefficient
and is practical.
[0108] Next, specific methods for producing the epoxy resin
composite formed article 1, the thermoplastic polymer composite
formed article 10, and the printed wiring boards 2 and 20 will be
described in detail with reference to FIGS. 6 to 10, and FIGS. 13
and 14.
[0109] At first, a method for producing the epoxy resin composite
formed article 1 formed into a plate-like shape according to the
first embodiment, as shown in FIG. 2, will be described. In FIG. 6,
a mold 11 is provided with a cavity 12 having a shape corresponding
to the desired shape of a formed article. At first, as shown in
FIG. 6, one fiber cloth 15 is disposed in the cavity 12 such that
the fiber cloth 15 is arranged along, or preferably parallel to,
the bottom surface of the cavity 12. Next, as shown in FIG. 7, the
cavity 12 is filled with the epoxy resin composition 16. At this
time, after multiple fiber cloths 15 have been disposed within the
cavity in a stacked manner, the epoxy resin composition 16 may be
flowed into the cavity to impregnate the multiple fiber cloths 15
with the epoxy resin composition 16. Alternatively, after one fiber
cloth 15 has been di-sposed in the cavity, the epoxy resin
composition 16 may be injected into the cavity to impregnate the
fiber cloth 15 with the epoxy resin composition 16, and then
another fiber cloth 15 may be disposed thereon. Repeating those
operations may result in multiple fiber cloths 15 stacked in the
formed article 1 thereby obtained.
[0110] A step for removing mixed air bubbles under reduced or
increased pressure is preferably performed during or after the step
of filling the epoxy resin composition 16.
[0111] The mold 11 is equipped with a heater (not shown) as
required. The epoxy resin composition 16 is maintained in a melted
state in the step of filling the epoxy resin composition 16. In
addition, the epoxy resin composition 16 is maintained in a liquid
crystal state when the epoxy resin composition 16 contains an epoxy
resin having a mesogenic group in a molecule.
[0112] Next, as shown in FIG. 8, the epoxy resin composition 16 in
the cavity 12 is applied with a magnetic field having a
predetermined magnetic flux density by a pair of permanent magnets
13 as magnetic field generators. The pair of permanent magnets 13
is arranged above and below the mold 11. In this embodiment, lines
of magnetic force M of a magnetic field generated by the permanent
magnets 13 are arranged matching to the thickness direction of the
cavity 12. The magnetic field may be applied to the mold 11 before
the cavity 12 is filled with the epoxy resin composition 16. At
this time, the lines of magnetic force M coincide with the
thickness direction of the epoxy resin composition 16, so the
molecular chains of an epoxy resin, or preferably the rigid
molecular chains of an epoxy resin having a mesogenic group in a
molecule can be oriented in the thickness direction of the epoxy
resin composition 16.
[0113] While the oriented state of the epoxy resin is maintained,
the epoxy resin composition is cured and removed from the mold 11.
As a result, the epoxy resin composite formed article 1 of the
present invention is obtained.
[0114] A prepreg in which each fiber cloth 15 is preliminarily
impregnated with the epoxy resin composition 16 may be used. The
prepreg may be heated to be in a melted state and applied with a
magnetic field so that the molecular chains of the epoxy resin are
oriented in the direction intersecting with the fiber cloth as
above-described. At this time, the epoxy resin must have melt
viscosity to the extent that molecular chains of the resin can be
oriented by a magnetic field upon heating.
[0115] Furthermore, when fibers are used instead of the fiber cloth
15 in the above production method, the cavity 12 of the mold 11 may
be filled with an epoxy resin composition added with the fibers in
advance. In this case, when the fibers are longer than the
thickness of the cavity 12, the major axis of the each fiber
spontaneously orients in the direction along the bottom surface of
the cavity 12. Of course, the major axis of the each fiber may be
oriented in the direction along the bottom surface of the cavity 12
by an external force such as a flow field or a shear field.
[0116] A method for producing the thermoplastic polymer composite
formed article 10 formed into a plate-like shape according to the
third embodiment, as shown in FIG. 11, will be described. In FIG.
13, the mold 11 is provided with the cavity 12 having a shape
corresponding to the desired shape of a formed article, namely a
plate shape in this embodiment. At first, as shown in FIG. 13, the
thermoplastic polymer composition 160 preformed into a sheet or a
flat plate is arranged in the cavity 12 along, or preferably
parallel to, the bottom surface of the cavity. Next, at least one
fiber cloth 15 is disposed along the upper surface of the sheet of
the thermoplastic polymer composition 160, or preferably parallel
to the bottom surface of the mold. Those operations are repeated to
laminate multiple thermoplastic polymer composition sheets and
multiple fiber cloths 15.
[0117] The mold 11 is equipped with a heater (not shown) for press
molding the laminated thermoplastic polymer composition sheets and
fiber cloths 15 under heat. During the press molding, the
thermoplastic polymer composition sheets are melted to be in liquid
states, and are then impregnated into the fiber cloths 15. In
addition, the thermoplastic polymer composition 160 is maintained
in a liquid crystal state, when the thermoplastic polymer
composition 160 contains a liquid crystal polymer having a
mesogenic group in a molecule. During the step of press molding
under heat, the cavity 12 is preferably vacuumed to prevent air
from mixing into the melted thermoplastic polymer composition 160.
Furthermore, as shown in FIG. 14, the pair of permanent magnets 13
is arranged as magnetic field generators above and below the mold
11. These permanent magnets 13 apply a magnetic field having a
predetermined magnetic flux density to the polymer composition 160
disposed in the cavity 12. In this embodiment, the lines of
magnetic force M of a magnetic field generated by the permanent
magnets 13 are directed to coincide with the thickness direction of
the cavity 12. As a result, the molecular chains of a thermoplastic
polymer, or preferably the rigid molecular chains of a liquid
crystal thermoplastic polymer having a mesogenic group in a
molecule can be oriented in the thickness direction of the
thermoplastic polymer composition 160 molded into a plate-like
shape in the cavity 12. The magnetic field may be applied to the
mold 11 before the thermoplastic polymer composition sheets are
laminated in the cavity 12.
[0118] While the oriented state of the thermoplastic polymer is
maintained, the thermoplastic polymer composition 160 is
solidified, for example, by cooling and removed from the mold 11.
As a result, the thermoplastic polymer composite formed article 10
of the present invention is obtained.
[0119] A sheet of the thermoplastic polymer composition 160 in
which a thermoplastic polymer is mixed with single fibers in
advance may be used in the above production method. When the
thermoplastic polymer composition 160 containing the single fibers
is preliminarily molded into a sheet-like shape, the major axis of
each single fiber spontaneously orients in the direction along the
surface of the sheet. While this sheet of the thermoplastic polymer
composition 160 is heated to be in a melted state, a magnetic field
is applied in the thickness direction of the sheet as described
above to orient the molecular chains of the thermoplastic polymer
in the direction intersecting with the single fibers.
[0120] As in the production method of the epoxy resin composite
formed article 1 of the first embodiment, the thermoplastic polymer
composite formed article 10 can be produced by: disposing a fiber
cloth(s) 15 in the cavity 12 of the mold 11 at first; and injecting
the thermoplastic polymer composition 160 in a melted state into
the cavity 12. In this case, the production method is substantially
same as that for the epoxy resin composite formed article 1 of the
first embodiment, except that the epoxy resin composition is
substituted by a melted thermoplastic polymer composition.
[0121] Furthermore, when single fibers are used instead of the
fiber cloth 15 in the production method, the thermoplastic polymer
composition 160 preliminarily added with single fibers maybe
injected into the cavity 12 of the mold 11. In this case, when a
fiber is longer than the thickness of the cavity 12, the major axis
of the fiber spontaneously orients in the direction along the
bottom surface of the cavity 12. The major axis of the fiber also
can be oriented in the direction along the bottom surface of the
cavity 12 by an external force such as a flow field or a shear
field. Such external force may be generated when the thermoplastic
polymer composition is injected into the cavity 12 of the mold
11.
[0122] In any case, the thermoplastic polymer composition must have
melting viscosity to the extent that its molecular chains can be
oriented by a magnetic field in a melted state.
[0123] To produce the printed wiring board of the second embodiment
shown in FIG. 3, in the production method of the epoxy resin
composite formed article 1 of the first embodiment, the conductive
layer 14a composed of, for example, metal foil is disposed on the
bottom surface of the cavity 12 prior to the step of disposing the
fiber cloth 15 in the cavity 12 of the mold 11, as shown in FIG. 9.
Furthermore, after the step of filling the cavity 12 with the epoxy
resin composition 16, as shown in FIG. 10, the conductive layer 14b
is additionally disposed on the epoxy resin composition 16 filled
into the cavity 12. After that, a magnetic field is applied to
orient the molecular chains of an epoxy resin in the thickness
direction of the epoxy resin composition 16 in the same manner as
in the production method of the first embodiment shown in FIG. 8.
While the oriented state of the epoxy resin is maintained, the
epoxy resin composition is cured and removed from the mold 11. As a
result, an epoxy resin composite formed article having the
conductive layers 14a and 14b disposed on both of its surfaces is
obtained. Furthermore, the conductive layers 14a and 14b are
patterned by means of a conventionally known method such as etching
to produce the printed wiring board 2 of the present invention.
[0124] In addition, a multi-layer printed wiring board can be
produced by disposing metal foil having a circuit formed therein in
advance between the above-mentioned prepregs.
[0125] To produce the printed wiring board of the fourth embodiment
shown in FIG. 12, as shown in FIG. 9, the conductive layer 14a
composed of, for example, metal foil is disposed on the bottom
surface of the cavity 12 prior to the step of disposing the
thermoplastic polymer composition 160 preliminarily molded into a
sheet-like shape and the fiber cloth 15 in the cavity 12 of the
mold 11 in the above-mentioned method of producing the
thermoplastic polymer composite formed article 10 of the third
embodiment. Furthermore, as shown in FIG. 10, the conductive layer
14b is additionally disposed on the thermoplastic polymer
composition 160 disposed at the uppermost portion in the cavity 12
after the step of laminating the thermoplastic polymer composition
160 and the fiber cloth 150 in the cavity 12. After that, a
magnetic field is applied to orient the molecular chains of a
thermoplastic polymer in the thickness direction of the
thermoplastic polymer composition 160 in the cavity 12 in the same
manner as in the production method of the third embodiment shown in
FIG. 8. While the oriented state of the thermoplastic polymer is
maintained, the thermoplastic polymer composition is solidified and
removed from the mold 11. As a result, a thermoplastic polymer
composite formed article having the conductive layers 14a and 14b
disposed on both of its surfaces is obtained. Furthermore, the
conductive layers 14a and 14b are patterned by means of a
conventionally known method such as etching to produce the printed
wiring board 20 of the present invention.
[0126] In addition, a multi-layer printed wiring board can be
produced by disposing a metal foil(s) having circuits preliminarily
formed therein between two polymer composition sheets when the
polymer composition sheet and the fiber cloth 15 are disposed in a
stack.
[0127] The above embodiments can be modified as described
below.
[0128] An epoxy resin composite formed article or a thermoplastic
polymer composite formed article is produced in advance, and a
conductive layer composed of metal foil or the like is integrated
with the epoxy resin composite formed article or the thermoplastic
polymer composite formed article through an adhesive layer or the
like to form a printed wiring board.
[0129] A metal-plated layer or a conductive paste layer is used as
a conductive layer instead of a metal foil. At this time, a prepreg
in which a fiber cloth is preliminarily impregnated with an epoxy
resin composition or a thermoplastic polymer composition may be
used, or an epoxy resin composite formed article or a thermoplastic
polymer composite formed article may be produced in advance.
[0130] In the epoxy resin composite formed article 1 or the
thermoplastic polymer composite formed article 10, each fiber cloth
may be arranged to be parallel to the thickness direction of the
formed article, and the molecular chains of an epoxy resin or a
thermoplastic polymer may be oriented to be parallel to the surface
of the formed article. In this case, in the above production
method, the pair of permanent magnets 13 is arranged on both sides
of the mold 11 to be opposed to each other in such a manner that
the lines of magnetic force M are parallel to the surface of the
epoxy resin composition 16 or the thermoplastic polymer composition
160 in the cavity 12.
[0131] The pair of permanent magnets 13 is arranged to sandwich the
mold 11 between them, but one of the permanent magnets 13 may be
omitted.
[0132] The pair of permanent magnets 13 is arranged in such a
manner that the S pole of one of the magnets is opposed to the N
pole of the other. However, the pair may be arranged in such a
manner that the S poles, or N poles, of both the magnets are
opposed to each other.
[0133] The lines of magnetic force M are linear, but may be curved
or the like. The pair of permanent magnets 13 is arranged in such
manners that the lines of magnetic force M extend in one direction.
However, the pair of permanent magnets 13 may be arranged in such
manners that the lines of magnetic force M extend in two or more
directions. Furthermore, one of one line M of magnetic force and
the mold 11 may be rotated.
[0134] A large number of single fibers may be used instead of a
fiber cloth. In this case, in the above production method, multiple
single fibers may be arranged in the cavity 12 to be parallel to
the surface of a formed article to be obtained before the cavity 12
is filled with the epoxy resin composition 16. Alternatively, the
epoxy resin composition 16 or the thermoplastic polymer composition
160 may be mixed with a single fiber in advance. In this case, as
described above, it must be noted the fibers are prevented from
being oriented in the same direction as the orientation direction
of the molecular chains of the epoxy resin or the thermoplastic
polymer upon the orientation of these molecular chains by a
magnetic field.
[0135] The fiber axis of a fiber in a formed article has only to be
oriented along a first plane, and is not needed to be exactly
parallel to the first plane. In addition, the molecular chains of
the epoxy resin or the thermoplastic polymer has only to be
oriented in the direction intersecting with the first plane, and is
not needed to be exactly perpendicular to the first plane.
[0136] Hereinafter, the above embodiments will be described more
specifically by way of examples and comparative examples. However,
these examples do not limit the scope of the present invention at
all.
EXAMPLES
[0137] Printed wiring board formed of epoxy resin composite formed
article
Example 1
[0138] A printed wiring board using the epoxy resin composite
formed article of the present invention as an insulating layer and
copper foil as a conductive layer was produced. The epoxy resin
composition 16 prepared by mixing
terephthalylidene-bis-(4-amino-3-methylphenol)diglycidyl ether,
having a mesogenic group in the main chain of a molecule, as an
epoxy resin and 4,4'-diamino-1,2-diphenylethane as a curing agent
in a ration of 1 mol:0.5 mole was used. A glass cloth "MS130"
manufactured by Asahi Fiber-Glass Co., Ltd. (having a weight of 106
g/m.sup.2 and a density of 19 fibers/25 mm) was used as the fiber
cloth 15. Copper foil (having a thickness of 18 .mu.m) was used as
each of the conductive layers 14a and 14b. The number of glass
cloths to be used was set in such a manner that the content of the
glass cloth in a formed article would be 8 vol %. Copper foil (the
conductive layer 14a) was disposed on the bottom surface of the
cavity 12 of the mold 11. Then three glass cloths 15 were disposed
over the foil to be parallel to the bottom surface of the cavity
12. After that, the mold 11 was heated to 170.degree. C. in
temperature, and then the cavity 12 was filled with the epoxy resin
composition 16 to impregnate the epoxy resin composition 16 into
the glass cloths 15. After that, another copper foil (the
conductive layer 14b) was disposed on the epoxy resin composition
16. After that, the composition 16 was cured at 170.degree. C. for
10 minutes in a magnetic field having a magnetic flux density of 10
tesla. Thus, a laminate of 2 mm in thickness was obtained. Next,
the laminate was drilled to form 200 holes each having a hole
diameter of 0.9 mm therein. The resultant was subjected to a copper
through-hole plating treatment and then patterned in such a manner
land diameter of each hole, a circuit width, and a circuit interval
would be 1.3 mm, 0.2 mm, and 0.2 mm, respectively. Thereby, the
printed wiring board 2 was obtained.
Examples 2 and 3
[0139] Each of the printed wiring boards 2 was produced in the same
manner as in Example 1 except that the number of glass cloths to be
disposed in the cavity 12 (the content of the glass cloth) was
changed as shown in Table 1.
Example 4
[0140] The printed wiring board 2 was produced in the same manner
as in Example 1 except that the number of glass cloths to be
disposed in the cavity 12 (the content of the glass cloth) and a
magnetic flux density were changed as shown in Table 1.
Example 5
[0141] The same epoxy resin as that of Example 1 and the same
curing agent as that of Example 1 were mixed in a ratio of 1
mole:0.5 mole. The mixture was added with glass fibers "CS03BC273"
manufactured by Asahi Fiber-Glass Co., Ltd. (each having a fiber
length of 3 mm) as single fibers, instead of the glass cloths of
Examples 1 to 4, to the epoxy resin composition 16. The amount of
glass fibers to be added was set in such a manner that the content
of the glass fibers in a formed article would be 21 vol %. The same
copper foil as that of Example 1 was used as each of the conductive
layers 14a and 14b. At first, copper foil (the conductive layer
14a) was disposed on the bottom surface of the cavity 12 of the
mold 11. After that, the mold 11 was heated to 170.degree. C., and
then the cavity 12 was filled with the epoxy resin composition 16.
Then, another copper foil (the conductive layer 14b) was disposed
on the epoxy resin composition 16. After that, the epoxy resin
composition 16 was cured at 170.degree. C. for 10 minutes in a
magnetic field having a magnetic flux density of 10 tesla. Thus, a
laminate of 2 mm in thickness was obtained. The directions of the
lines of magnetic force M were aligned with the thickness direction
of the laminate. Next, the laminate was used to produce the printed
wiring board 2 in the same manner as in Example 1.
Example 6
[0142] An epoxy resin composition obtained by mixing the same epoxy
resin as that of Example 1 and of the same curing agent in a ratio
of 1 mole:0.5 mole as that of Example 1 was used. The same glass
cloth as that of Example 1 was used as a fiber cloth. The same
copper foil as that of Example 1 was used as each of the conductive
layers 14a and 14b. The number of glass cloths to be used was set
in such a manner that the content of the glass cloth in a formed
article would be 17 vol %. At first, one glass cloth 15 was
impregnated with the epoxy resin composition 16 melted by heating.
After that, the resultant was solidified by cooling in a magnetic
field having a magnetic flux density of 10 tesla to produce a
prepreg. Copper foil was disposed in the cavity 12 of the same mold
11 as that of Example 1, and ten prepregs thus obtained were
disposed in a stack over the copper foil. Furthermore, another
copper foil was disposed on the resultant. The resultant was heated
and pressurized at 170.degree. C. in a magnetic field having a
magnetic flux density of 10 tesla to produce a laminate of 2 mm in
thickness. The directions of the lines of magnetic force M were
aligned with the thickness direction of the laminate. Next, the
laminate was used to produce the printed wiring board 2 in the same
manner as in Example 1.
Comparative Example 1
[0143] The epoxy resin composition 16 was used to produce a printed
wiring board containing neither fiber cloth nor single fibers. The
epoxy resin composition 16 was prepared by mixing of
terephthalylidene-bis-(4-amino-3-methylphenol)diglycidyl ether
having a mesogenic group in a molecule as an epoxy resin and of
4,4'-diamino-1,2-diphenylethane as a curing agent in a ratio of 1
mole:0.5 mole. The same copper foil as that of Example 1 was used
as a conductive layer. At first, copper foil (the conductive layer
14a) was disposed on the bottom surface of the cavity 12 of the
mold 11. After that, the mold 11 was heated to 170.degree. C., and
then the cavity 12 was filled with the epoxy resin composition 16.
After that, another copper foil (the conductive layer 14b) was
disposed on the epoxy resin composition 16. Then, the epoxy resin
composition 16 was cured at 170.degree. C. for 10 minutes with no
magnetic field applied to produce a laminate of 2 mm in thickness.
Next, the laminate was used to produce the printed wiring board 2
in the same manner as in Example 1.
Comparative Example 2
[0144] An epoxy resin composition prepared by mixing
terephthalylidene-bis-(4-amino-3-methylphenol)diglycidyl ether
having a mesogenic group in a molecule as an epoxy resin and
4,4'-diamino-1,2-diphenylethane as a curing agent in a ratio of 1
mole:0.5 mole was used to produce a printed wiring board containing
neither fiber cloth nor fiber. The same copper foil as that of
Example 1 was used as a conductive layer. Copper foil (the
conductive layer 14a) was disposed on the bottom surface of the
cavity 12 of the mold 11. After that, the mold 11 was heated to
170.degree. C., and then the cavity 12 was filled with the epoxy
resin composition. After that, another copper foil (the conductive
layer 14b) was disposed on the epoxy resin composition 16. Next,
the resultant was cured at 170.degree. C. for 10 minutes in a
magnetic field having a magnetic flux density of 10 tesla to
produce a printed wiring board having a thickness of 2 mm. The
directions of the lines of magnetic force M were aligned with the
thickness direction of the laminate. Next, the laminate was used to
produce the printed wiring board 2 in the same manner as in Example
1.
Comparative Example 3
[0145] The same epoxy resin composition 16, glass cloth, and copper
foil as those of Example 1 were used. The number of glass cloths
was set in such a manner that the content of the glass cloth in a
formed article would be 17 vol %. At first, copper foil (the
conductive layer 14a) was disposed on the bottom surface of the
cavity 12 of the mold 11, and ten glass cloths were disposed in a
stack over the foil to be parallel to the bottom surface of the
cavity 12. After that, the mold 11 was heated to 170.degree. C.,
and then the cavity 12 was filled with the epoxy resin composition
16 to impregnate the epoxy resin composition 16 into the glass
cloths 15. After that, another copper foil (the conductive layer
14b) was disposed on the epoxy resin composition 16. After that,
the epoxy resin composition 16 was cured at 170.degree. C. for 10
minutes with no magnetic field applied. Thus, a laminate of 2 mm in
thickness was obtained. Next, the laminate was used to produce the
printed wiring board 2 in the same manner as in Example 1.
[0146] As for a portion of the epoxy resin composite formed article
in each of the printed wiring boards produced in Examples 1 to 6
and Comparative Example 2, the degree of orientation .alpha. of the
epoxy resin of was measured. A test piece (2 mm in thickness) was
used to determine the degree of orientation .alpha. of the epoxy
resin from an X-ray diffraction pattern measured by means of an
X-ray diffraction instrument ("M18XHF.sup.22-SRA" manufactured by
MAC Science Co., Ltd). Each test piece is composed only of the
epoxy resin composite formed article portion of each of the printed
wiring boards of Examples 1 to 6 and Comparative Example 2.
[0147] In addition, the thermal expansion coefficients of the epoxy
resin composite formed article portion of each of the printed
wiring boards 2 produced in the respective examples and comparative
examples in the direction along the surface of the printed wiring
board 2 and in the thickness direction of the printed wiring board
2 were measured. A test piece (2 mm) was used to measure a thermal
expansion coefficient by means of an apparatus for thermomechanical
analysis ("TMA-50" manufactured by Shimadzu Corporation) at a load
of 3 g and a rate of temperature increase of 10.degree. C./min.
Each test piece is composed only of the epoxy resin composite
formed article portion of each of the printed wiring boards of the
respective examples and comparative examples.
[0148] Furthermore, a through-hole reliability test was conducted
on each of the printed wiring boards 2. Each of the printed wiring
boards 2 was immersed in oil at 260.degree. C. for 10 seconds and
in water at 20.degree. C. for 10 seconds in conformance with
JIS-C0025. This operation was defined as one cycle. The cycle was
repeated, and the number of cycles at which any breakage of wirings
occurred was counted.
[0149] Table 1 shows the measured values and test results of the
printed wiring boards produced in Examples 1 to 6 and Comparative
Examples 1 to 3. TABLE-US-00001 TABLE 1 Comparative Example Example
1 2 3 4 5 6 1 2 3 Content of glass cloth (vol %) 8 (3) 14 (5) 17
(10) 17 (10) -- 17 (10) -- -- 17 (10) (Number of glass cloths)
Content of glass fibers (vol %) -- -- -- -- 21 -- -- -- Magnetic
flux density (tesla) 10 10 10 5 10 10 0 10 0 Degree of orientation
.alpha. 0.72 0.72 0.72 0.70 0.72 0.70 -- 0.72 -- Thermal expansion
coefficient 18 20 23 21 10 25 66 3.5 93 in thickness direction
(10.sup.-6/K) Thermal expansion coefficient 40 21 15 16 40 14 69
105 17 in direction along surface (10.sup.-6/K) Through-hole
reliability 160 250 270 265 230 255 50 70 20 (Number of cycles)
[0150] As is apparent from the results shown in Table 1, in each of
Examples 1 to 4 and 6, each of the thermal expansion coefficients
in the direction along the surface of the wiring board in which the
glass cloth extends and in the thickness direction in which the
molecular chains of the epoxy resin were oriented exhibited a lower
value, namely, 40.times.10.sup.-6/K or less. In Example 5 as well,
the thermal expansion coefficient in the direction along the
surface of the wiring board as well as that in the thickness
direction in which the molecular chains of the epoxy resin was
oriented exhibited a lower value (40.times.10.sup.-6/K or less).
The reason for this is probably as follows. The each fiber axis of
the glass fibers added to the epoxy resin composition 16 were
oriented in the direction along the surface of the wiring board
because the composition was molded into a plate-like shape. Even
when a magnetic field was applied thereafter, the fibers were
hardly influenced by the magnetic field because of its relative
long fiber length (3 mm), and hence the oriented state was
maintained. Accordingly, in each of Examples 1 to 6, the difference
between the thermal expansion coefficient in the direction along
the surface and the thermal expansion coefficient in the thickness
direction is at most 30.times.10.sup.-6/K (in Example 3). This
shows that a printed wiring board composed of an epoxy resin
composite in which thermal expansion coefficients are controlled to
be small in both the direction along the surface of the wiring
board and the thickness direction were obtained in each of these
Examples. In addition, each of the printed wiring boards of
Examples 1 to 6 had better through-hole reliability than that of
each of the printed wiring boards of Comparative Examples 1 to
3.
[0151] On the other hand, in Comparative Example 1, the difference
between the thermal expansion coefficients in the direction along
the surface of the wiring board and in the thickness direction was
small, but each of the thermal expansion coefficients exceeded
60.times.10.sup.-6/K. In Comparative Example 2, the thermal
expansion coefficient in the thickness direction, in which the
molecular chains of the epoxy resin were oriented, showed a lower
value, but the thermal expansion coefficient in the direction along
the surface showed an extremely higher value. In Comparative
Example 3, the thermal expansion coefficient in the direction along
the surface in which a glass cloth expanded showed a lower value,
but the thermal expansion coefficient in the thickness direction
showed a higher value. In addition, none of the printed wiring
boards of Comparative Examples 1 to 3 provided sufficient
through-hole reliability.
[0152] Printed wiring board formed of thermoplastic polymer
composite formed article
Example 7
[0153] A printed wiring board using the thermoplastic polymer
composite formed article 10 of the present invention as an
insulating layer and copper foil as a conductive layer was
produced. The thermoplastic polymer composition 160 containing a
thermoplastic polymer including 4-hydroxy benzoate/(terephthalic
acid and ethylene glycol (molar ratio 1:1))=80/20 mol% as a
repeating unit was used. A "1080" manufactured by Asahi-Schwebel
Co., Ltd. serving as a glass cloth (having a weight of 48 g/m.sup.2
and a density of 60 (vertical).times.47 (horizontal) fibers/inch)
was used as the fiber cloth 15. Electrolytic copper foil
manufactured by NIKKO MATERIALS Co., Ltd. (having a thickness of 18
.mu.m) was used as each of the conductive layers 14a and 14b. The
number of glass cloths to be used was set in such a manner that the
content of the glass cloth in a formed article would be 3.7 vol
%.
[0154] At first, copper foil (the conductive layer 14a) was
disposed on the bottom surface of the cavity 12 of the mold 11.
Then the thermoplastic polymer composition 160 preliminarily molded
into a sheet having a thickness of 0.40 mm and the glass cloth 15
were disposed in a stack over the foil to be parallel to the bottom
surface of the cavity 12. Four tiers each composed of the
thermoplastic polymer composition 160 and the glass cloth 150 were
superimposed, and then a sheet of the thermoplastic polymer
composition 160 was disposed thereover. Then, another copper foil
(the conductive layer 14b) was disposed on the resultant. After
that, the mold was heated and pressurized at 310.degree. C. for 15
minutes in a magnetic field having a magnetic flux density of 10
tesla, and was then slowly cooled to room temperature to produce a
laminate of 2 mm in thickness. The directions of the lines of
magnetic force M were aligned with the thickness direction of the
laminate. Next, the laminate was drilled to form 200 holes each
having a hole diameter of 0.9 mm therein, and was subjected to a
copper through-hole plating treatment. After that, the resultant
was patterned in such a manner that the land diameter of each hole,
the circuit width, and the circuit interval would be 1.3 mm, 0.2
mm, and 0.2 mm, respectively, to thereby produce the printed wiring
board 20.
Example 8
[0155] The printed wiring board 20 was produced in the same manner
as in Example 7 except that the number of glass cloths to be
disposed in the cavity 12 (the content of the glass cloth) was
changed as shown in Table 2.
Example 9
[0156] The printed wiring board 20 was produced in the same manner
as in Example 7 except that the number of glass cloths to be
disposed in the cavity 12 (the content of the glass cloth) and a
magnetic flux density were changed as shown in Table 2.
Example 10
[0157] The printed wiring board 20 was produced in the same manner
as in Example 7 except that: the thermoplastic polymer composition
160 synthesized by reacting 2,2'-bipyridine-4,4'-dicarboxylic acid
with 1,12-diaminododecane was used as a thermoplastic polymer; and
the number of glass cloths to be disposed in the cavity 12 (the
content of the glass cloth) was changed as shown in Table 2.
Example 11
[0158] The same thermoplastic polymer as that of Example 7 was
mixed with glass fibers "CS03BC273" manufactured by Asahi
Fiber-Glass Co., Ltd. (1 mm in fiber length) as single fibers
instead of the glass cloths of Examples 7 to 10 to prepare the
thermoplastic polymer composition 160. The amount of glass fibers
to be added was set in such a manner that the content of the glass
fibers in the thermoplastic polymer composition 160 would be 19 vol
%. At first, the thermoplastic polymer composition 160 was injected
into the mold 11 placed in a magnetic field having a magnetic flux
density of 10 tesla. The resultant was heated and pressurized at
310.degree. C. for 15 minutes, and was then slowly cooled to room
temperature. Thereby, the thermoplastic polymer composite formed
article 10 having a thickness of 2 mm was obtained. The directions
of the lines of magnetic force M were aligned with the thickness
direction of the formed article. Next, both surfaces of the
thermoplastic polymer composite formed article 10 were plated with
copper to form the conductive layers 14a and 14b. The thermoplastic
polymer composite formed article 10 having the conductive layers
14a and 14b was patterned in the same manner as in Example 1 to
produce the printed wiring board 20.
Comparative Example 4
[0159] A thermoplastic polymer composition 160 identical to that of
each of Examples 7 to 9 was used to produce a printed wiring board
containing neither fiber cloth nor fiber. The same copper foil as
that of Example 7 was used as a conductive layer. At first, copper
foil (the conductive layer 14a) was disposed on the bottom surface
of the cavity 12 of the mold 11. After that, the thermoplastic
polymer composition 160 preliminarily molded into a sheet of 2 mm
in thickness was disposed on the foil to be parallel to the bottom
surface of the cavity 12. Then, another copper foil (the conductive
layer 14b) was disposed on the composition. The mold was heated and
pressurized at 310.degree. C. for 15 minutes with no magnetic field
applied, and was then slowly cooled to room temperature to produce
a laminate of 2 mm in thickness. Next, the laminate was used to
produce a printed wiring board in the same manner as in Example
1.
Comparative Example 5
[0160] The thermoplastic polymer composition 160 identical to that
of each of Examples 7 to 9 was used to produce a printed wiring
board containing neither fiber-cloth nor fiber. The same copper
foil as that of Example 7 was used as a conductive layer. At first,
copper foil (the conductive layer 14a) was disposed on the bottom
surface of the cavity 12 of the mold 11. After that, the
thermoplastic polymer composition 160 preliminarily molded into a
sheet of 2 mm in thickness was arranged on the foil to be parallel
to the bottom surface of the cavity 12. Then, another copper foil
(the conductive layer 14b) was disposed on the composition. After
that, the mold-was heated and pressurized at 310.degree. C. for 15
minutes in a magnetic field having a magnetic flux density of 10
tesla, and was then slowly cooled to room temperature to produce a
laminate of 2 mm in thickness. The directions of the lines of
magnetic force M were aligned with the thickness direction of the
laminate. Next, the laminate was used to produce a printed wiring
board in the same manner as in Example, b 7.
Comparative Example 6
[0161] A printed wiring board was produced in the same manner as in
Example 9 using a thermoplastic polymer composition and a glass
cloth composed of the same materials in the same amounts as those
of Example 9 except that no magnetic field was applied upon
molding.
[0162] As for the thermoplastic polymer composite formed article
portion of each of the printed wiring boards produced in Examples 7
toll and Comparative Examples 4 to 6, the degree of orientation
.alpha. of the thermoplastic polymer, and thermal expansion
coefficients in the direction along the surface of the printed
wiring board and in the thickness direction of the printed wiring
board were measured in the same manners as those described above
with respect to Examples 1 to 6 and Comparative Example 2. The
degree of orientation ay in each of Comparative Examples 4 and 6
could not be calculated because no peak was observed in the X-ray
diffraction intensity distribution of a test piece of the each of
these Comparative Examples.
[0163] Furthermore, a through-hole reliability test was conducted
on each of the printed wiring boards. Each of the printed wiring
boards 2 was immersed in silicone oil at 260.degree. C. for 5
seconds and in 2-propanol at 20.degree. C. for 20 seconds in
conformance with JIS-C5012. This operation was defined as one
cycle. The cycle was repeated, and the number of cycles at which
cracking, peeling, or breaking of wiring occurred was counted.
[0164] Table 2 shows the measured values and test results of the
printed wiring boards produced in Examples 7 to 11 and Comparative
Examples 4 to 6. TABLE-US-00002 TABLE 2 Comparative Example Example
7 8 9 10 11 4 5 6 Content of glass cloth (vol %) 3.7 (4) 6.5 (7)
6.5 (7) 5.6 (6) -- -- -- 6.5 (7) (Number of glass cloths) Content
of glass fibers (vol %) -- -- -- -- 19 -- -- -- Magnetic flux
density (tesla) 10 10 5 10 10 0 10 0 Degree of orientation .alpha.
0.82 0.82 0.78 0.81 0.83 -- 0.90 -- Thermal expansion coefficient 6
10 22 25 28 181 -1 127 in thickness direction (10.sup.-6/K) Thermal
expansion coefficient 35 20 13 29 27 44 178 13 in direction along
surface (10.sup.-6/K) Through-hole reliability 196 263 254 260 258
59 23 33 (Number of cycles)
[0165] As is apparent from the results shown in Table 2, in each of
Examples 7 to 10, each of the thermal expansion coefficients in the
direction along the surface of the wiring board in which a glass
cloth extended and in the thickness direction in which the
molecular chains of the thermoplastic polymer were oriented
exhibited a lower value (35.times.10.sup.-6/K or less). In Example
5, in which a glass single fiber was used, as well, the thermal
expansion coefficient in the direction along the surface of the
wiring board as well as that in the thickness direction in which
the molecular chains of the thermoplastic polymer was oriented
exhibited a lower value (28.times.10.sup.-6/K or less). The reason
for this is probably as follows. Each major axis of the glass
fibers in the thermoplastic polymer composition 160 were oriented
in the direction along the bottom surface of the cavity 12 of the
mold 11, that is, the direction along the surface of the laminate
owing to a flow of the composition 160 caused by injecting the
composition 160 into the cavity 12. Even when a magnetic field was
applied in the thickness direction of the laminate thereafter, the
glass fiber was hardly influenced by the magnetic field because of
its small anisotropic diamagnetic susceptibility .chi..sub.a, and
hence the oriented state was maintained.
[0166] Accordingly, in a printed wiring board obtained in each of
Examples 7 to 11, the difference between the thermal expansion
coefficients in the direction along the surface and in the
thickness direction is at most 29.times.10.sup.-6/K (Example 1).
This shows that a printed wiring board composed of a thermoplastic
polymer composite formed article in which thermal expansion
coefficients are controlled to be small in both the direction along
the surface of the wiring board and in the thickness direction was
obtained in these embodiments. In addition, each of the printed
wiring boards of Examples 7 to 11 had better through-hole
reliability than that of each of the printed wiring boards of
Comparative Examples 4 to 6.
[0167] On the other hand, in Comparative Example 4, the thermal
expansion coefficient in the direction along the surface showed a
relatively lower value, but the thermal expansion coefficient in
the thickness direction showed a higher value. In Comparative
Example 5, the thermal expansion coefficient in the thickness
direction in which the molecular chains of the thermoplastic
polymer were oriented showed an extremely lower value, but the
thermal expansion coefficient in the direction along the surface
showed a higher value. In Comparative Example 6, the thermal
expansion coefficient in the direction along the surface in which a
glass cloth expanded showed a lower value, but the thermal
expansion coefficient in the thickness direction showed a higher
value. In addition, none of the printed wiring boards of
Comparative Examples 4 to 6 provided sufficient through-hole
reliability.
* * * * *