U.S. patent application number 13/195802 was filed with the patent office on 2011-11-17 for dry film and multilayer printed wiring board.
This patent application is currently assigned to TAIYO HOLDINGS CO., LTD.. Invention is credited to Makoto HAYASHI, Katsuto Murata, Koshin Nakai.
Application Number | 20110278053 13/195802 |
Document ID | / |
Family ID | 41430078 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110278053 |
Kind Code |
A1 |
HAYASHI; Makoto ; et
al. |
November 17, 2011 |
DRY FILM AND MULTILAYER PRINTED WIRING BOARD
Abstract
A dry film includes a supporting base film and a thin membrane
of a thermosetting resin composition. The thin membrane of the
thermosetting resin composition is formed on the supporting base
film. The thermosetting resin composition includes a liquid epoxy
resin, a solid epoxy resin, a semisolid epoxy resin, an epoxy
curing agent and a filler. The liquid epoxy resin is liquid at
20.degree. C. and has at least two epoxy groups in a molecule. The
solid epoxy resin is solid at 40.degree. C. and has at least three
epoxy groups in a molecule. The semisolid epoxy resin is solid at
20.degree. C. and liquid at 40.degree. C. and has at least two
epoxy groups in a molecule. A ratio of mass of the liquid epoxy
resin to a sum of mass of the solid epoxy resin and mass of the
semisolid epoxy resin is about 1:1 to about 1:10 A ratio of the
mass of the solid epoxy resin to the mass of the semisolid epoxy
resin is about 1:0.5 to about 1:2.
Inventors: |
HAYASHI; Makoto; (Saitama,
JP) ; Nakai; Koshin; (Saitama, JP) ; Murata;
Katsuto; (Saitama, JP) |
Assignee: |
TAIYO HOLDINGS CO., LTD.
Tokyo
JP
|
Family ID: |
41430078 |
Appl. No.: |
13/195802 |
Filed: |
August 1, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12240815 |
Sep 29, 2008 |
7989561 |
|
|
13195802 |
|
|
|
|
Current U.S.
Class: |
174/258 ;
523/427 |
Current CPC
Class: |
C08G 59/38 20130101;
C08L 63/00 20130101; H05K 3/4661 20130101; C08L 63/00 20130101;
H05K 2201/0209 20130101; H05K 3/381 20130101; C08L 2666/22
20130101 |
Class at
Publication: |
174/258 ;
523/427 |
International
Class: |
H05K 1/03 20060101
H05K001/03; C08L 63/00 20060101 C08L063/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2008 |
JP |
2008-162215 |
Claims
1. A dry film comprising: a supporting base film; and a thin
membrane of a thermosetting resin composition formed on the
supporting base film, the thermosetting resin composition
comprising: a liquid epoxy resin being liquid at 20.degree. C. and
having at least two epoxy groups in a molecule; a solid epoxy resin
being solid at 40.degree. C. and having at least three epoxy groups
in a molecule; a semisolid epoxy resin being solid at 20.degree. C.
and liquid at 40.degree. C. and having at least two epoxy groups in
a molecule; an epoxy curing agent; and a filler, wherein a ratio of
mass of the liquid epoxy resin to a sum of mass of the solid epoxy
resin and mass of the semisolid epoxy resin is about 1:1 to about
1:10, and wherein a ratio of the mass of the solid epoxy resin to
the mass of the semisolid epoxy resin is about 1:0.5 to about
1:2.
2. A multilayer printed wiring board comprising: an inner layer
circuit substrate; a conductor layer having a predetermined circuit
pattern; and a resin insulation layer comprising a cured coating of
a thermosetting resin composition, the conductor layer and the
resin insulation layer being alternately provided on the inner
layer circuit substrate, the resin insulation layer having a
boundary face which has a microscopic concave-convex roughened
surface and to which the conductor layer is bonded, and the
thermosetting resin composition comprising: a liquid epoxy resin
being liquid at 20.degree. C. and having at least two epoxy groups
in a molecule; a solid epoxy resin being solid at 40.degree. C. and
having at least three epoxy groups in a molecule; a semisolid epoxy
resin being solid at 20.degree. C. and liquid at 40.degree. C. and
having at least two epoxy groups in a molecule; an epoxy curing
agent; and a filler, wherein a ratio of mass of the liquid epoxy
resin to a sum of mass of the solid epoxy resin and mass of the
semisolid epoxy resin is about 1:1 to about 1:10, and wherein a
ratio of the mass of the solid epoxy resin to the mass of the
semisolid epoxy resin is about 1:0.5 to about 1:2.
3. A multilayer printed wiring board comprising: an inner layer
circuit substrate; a conductor layer having a predetermined circuit
pattern; and a resin insulation layer comprising a dry film
according to claim 1, the conductor layer and the resin insulation
layer being alternately provided on the inner layer circuit
substrate, the resin insulation layer having a boundary face which
has a microscopic concave-convex roughened surface and to which the
conductor layer is bonded.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional application of the
U.S. patent application Ser. No. 12/240,815 filed Sep. 29, 2008,
which claims priority under 35 U.S.C. .sctn.119 to Japanese Patent
Application No. 2008-162215, filed Jun. 20, 2008. The contents of
these applications are incorporated herein by reference in their
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a dry film and a multilayer
printed wiring board.
[0004] 2. Discussion of the Background
[0005] As a process for producing a multilayer printed wiring
board, a production technique of buildup method that an organic
insulation layer and a conductor layer are alternately built up on
the conductor layer of an inner layer circuit substrate has been
paid to attention in recent years. For example, there is proposed a
process for producing a multilayer printed wiring board that an
epoxy resin composition is coated on a circuit-formed inner layer
circuit substrate and heat cured, then a concave-convex roughened
surface is formed on the surface by a roughening agent, and a
conductor layer is formed by plating (see Japanese Unexamined
Patent Publication 07-304931 and Japanese Unexamined Patent
Publication 07-304933). Further, there is proposed a process for
producing a multilayer printed wiring board that an adhesion sheet
of an epoxy resin composition is laminated on a circuit-formed
inner layer circuit substrate and heat cured, then a concave-convex
roughened surface is formed on the surface by a roughening agent,
and a conductor layer is formed by plating (see Japanese Unexamined
Patent Publication 11-87927).
[0006] A process for producing a multilayer printed wiring board by
a conventional buildup method will be explained as an example with
reference to FIG. 1; first, outer layer conductor patterns 8 are
formed on both sides of a laminated substrate X that an inner layer
conductor pattern 3 and a resin insulation layer 4 are previously
formed on both surfaces of an insulation substrate 1, on which an
epoxy resin composition is coated by a suitable method such as
screen printing method, splay coating method and curtain coating
method, then heat cured, thereby to form a resin insulation layer
9. (In the case of using a dry film or prepreg, it is heat cured by
lamination or hot plate press to form a resin insulation layer
9.)
[0007] Subsequently, a through-hole 21 penetrating a resin
insulation layer 9 and a laminated substrate X, and a via hole (not
shown) for electrically connecting connection parts in each
conductor layer are formed. Boring can be conducted by a suitable
means such as drill, mold punch and laser light. Thereafter,
roughening of each resin insulation layer 9 using a roughening
agent and desmear of hole parts are conducted. In general,
roughening treatment of the cured coating of an epoxy resin
composition on an inner layer circuit substrate is conducted as
follows; the entire surface of the cured composition is swelled
with an organic solvent such as N-methyl-2-pyrrolidone,
N,N-dimethylformamide and methoxypropanol, or an alkaline aqueous
solution such as sodium hydroxide and potassium hydroxide, and
roughened using an oxidant such as bichromate, permanganate, ozone,
hydrogen peroxide/sulfuric acid and nitric acid.
[0008] Next, a conductor layer is formed on the surface of resin
insulation layer 9 by nonelectrolytic plating, electrolytic
plating, or a combination of nonelectrolytic plating and
electrolytic plating. The process for forming a conductor layer by
nonelectrolytic plating is a process where the entire surface of
the cured composition is immersed in an aqueous solution containing
a catalyst for plating to adsorb the catalyst, then, immersed in a
plating solution to precipitate plating. The conductor layer in
this case is coated not only on the surface of resin insulation
layer 9 but also coated on the whole surface in the through-hole 21
and blind holes. Subsequently, in accordance with a common method
(subtractive method, semi-additive method, and the like), a
predetermined circuit pattern is formed in a conductor layer on the
surface of resin insulation layer 9 to form an outermost layer
conductor pattern 10 on both sides as shown in FIG. 1. In this
case, a plating layer is also formed in the through-hole 21 as
described above, as a result, a connection part 22 of outermost
layer conductor pattern 10 and a connection part 3a of inner layer
conductor pattern 3 of the multilayer printed wiring board are
electrically connected, and a through-hole 20 is formed. Further,
in the case of producing a multilayer printed wiring board, the
resin insulation layer and conductor layer may alternately be built
up. Additionally, in the buildup, an example of forming the resin
insulation layer and conductor layer on the laminated substrate has
been explained, but in place of a laminated substrate, a
single-sided substrate or a double-sided substrate may be used.
[0009] As described above, as a composition used for forming an
interlayer insulation layer of a multilayer printed wiring board,
an epoxy resin composition is generally used. However, since cured
coatings of the conventional epoxy resin composition are difficult
to form a good concave-convex roughened surface by roughening
treatment, there has been a problem that adhesion strength to a
conductor layer is low.
[0010] Further, in accompanying with the development of
miniaturization and high performance of electric appliances,
buildup layers in a multilayer printed wiring board are
multilayered, there have been increasing demands of a multilayer
printed wiring board having a multi-via structure called a
staggered via or a stacked via that a via hole is connected across
a plurality of buildup insulation layers. In the multilayer printed
wiring board having such multi-via structure, since coefficients of
thermal expansion of copper wiring for connecting via holes and an
insulation layer are markedly different, when reliability tests
such as thermal cycle are carried out, there has been posed a
problem that copper wiring or an insulation layer is cracked.
[0011] Then, in order to suppress the coefficient of thermal
expansion of a resin composition composing an insulation layer low
and to enhance peel strength (peeling strength) of a conductor
layer formed by plating, there has been proposed a resin
composition for interlayer insulation of a multilayer printed
wiring board (see Japanese Unexamined Patent Publication No.
2005-154727) as follows: it comprises (a) an epoxy resin being
liquid at a temperature of 20.degree. C. having an epoxy group of
two or more in a molecule, (b) a solid epoxy resin of aromatic
series having an epoxy group of three or more in a molecule and an
epoxy equivalent of 200 or less, (c) a phenol series curing agent,
(d) at least one resin having a glass transition temperature of
100.degree. C. or more selected from the group consisting of a
phenoxy resin, a polyvinyl acetal resin, a polyamide resin and a
polyamideimide resin, wherein the ratio of the component (a) and
component (b) to the epoxy resin is 1:0.3 to 1:2 in weight ratio,
the ratio of an epoxy group in the resin composition to a phenolic
hydroxyl group in the phenol series curing agent of component (c)
is 1:0.5 to 1:1.5, and the content of the resin of component (d) is
2 to 20% by weight of the resin composition.
[0012] As the resin composition for interlayer insulation, by
containing two kinds of epoxy resins of liquid epoxy resin and
solid epoxy resin and a phenoxy resin, and the like having a glass
transition temperature of 100.degree. C. or more, the coefficient
of thermal expansion of the resulting thermosetting resin
composition can be suppressed low. However, in a state before
curing (dry coating, dry film and prepreg), although measurements
by an Erichsen tester at low test speed show relatively high
values, measurements show low values at high test speed because the
compound ratio of a solid epoxy resin is low, so a point to be
improved on handling in processing a board has been left yet.
[0013] The contents of Japanese Unexamined Patent Publication
07-304931, Japanese Unexamined Patent Publication 07-304933,
Japanese Unexamined Patent Publication 11-87927, and Japanese
Unexamined Patent Publication No. 2005-154727 are incorporated
herein by reference in their entirety.
SUMMARY OF THE INVENTION
[0014] According to one aspect of the present invention, a dry film
includes a supporting base film and a thin membrane of a
thermosetting resin composition. The thin membrane of the
thermosetting resin composition is formed on the supporting base
film. The thermosetting resin composition includes a liquid epoxy
resin, a solid epoxy resin, a semisolid epoxy resin, an epoxy
curing agent and a filler. The liquid epoxy resin is liquid at
20.degree. C. and has at least two epoxy groups in a molecule. The
solid epoxy resin is solid at 40.degree. C. and has at least three
epoxy groups in a molecule. The semisolid epoxy resin is solid at
20.degree. C. and liquid at 40.degree. C. and has at least two
epoxy groups in a molecule. A ratio of mass of the liquid epoxy
resin to a sum of mass of the solid epoxy resin and mass of the
semisolid epoxy resin is about 1:1 to about 1:10 A ratio of the
mass of the solid epoxy resin to the mass of the semisolid epoxy
resin is about 1:0.5 to about 1:2.
[0015] According to another aspect of the present invention, a
multilayer printed wiring board includes an inner layer circuit
substrate, a conductor layer and a resin insulation layer. The
conductor layer has a predetermined circuit pattern. The resin
insulation layer includes a cured coating of a thermosetting resin
composition. The conductor layer and the resin insulation layer are
alternately provided on the inner layer circuit substrate. The
resin insulation layer has a boundary face which has a microscopic
concave-convex roughened surface and to which the conductor layer
is bonded. The thermosetting resin composition includes a liquid
epoxy resin, a solid epoxy resin, a semisolid epoxy resin, an epoxy
curing agent and a filler. The liquid epoxy resin is liquid at
20.degree. C. and has at least two epoxy groups in a molecule. The
solid epoxy resin is solid at 40.degree. C. and has at least three
epoxy groups in a molecule. The semisolid epoxy resin is solid at
20.degree. C. and liquid at 40.degree. C. and has at least two
epoxy groups in a molecule. A ratio of mass of the liquid epoxy
resin to a sum of mass of the solid epoxy resin and mass of the
semisolid epoxy resin is about 1:1 to about 1:10. A ratio of the
mass of the solid epoxy resin to the mass of the semisolid epoxy
resin is about 1:0.5 to about 1:2.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0017] FIG. 1 is a partially sectional view showing a schematic
constitution of the multilayer printed wiring board produced by a
conventional buildup method; and
[0018] FIGS. 2A and 2B are schematic side views showing two test
tubes used in determination of liquid form of an epoxy resin.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] According to a first embodiment of the present invention, a
thermosetting resin composition includes a liquid epoxy resin, a
solid epoxy resin, a semisolid epoxy resin, an epoxy curing agent,
and a filler. The liquid epoxy resin is liquid at 20.degree. C. and
has at least two epoxy groups in a molecule. A solid epoxy resin is
solid at 40.degree. C. and has at least three epoxy groups in a
molecule. A semisolid epoxy resin is solid at 20.degree. C. and
liquid at 40.degree. C. and has at least two epoxy groups in a
molecule. A ratio of mass of the liquid epoxy resin to a sum of
mass of the solid epoxy resin and mass of the semisolid epoxy resin
is about 1:1 to about 1:10, and a ratio of the mass of the solid
epoxy resin to the mass of the semisolid epoxy resin is about 1:0.5
to about 1:2.
[0020] According to a second embodiment of the present invention, a
dry film includes a thin membrane of the thermosetting resin
composition according to the first embodiment of the invention, and
a supporting base film. The thin membrane of the thermosetting
resin composition is formed on the supporting base film.
[0021] According to a third embodiment of the present invention, a
multilayer printed wiring board includes an inner layer circuit
substrate, a conductor layer, and a resin insulation layer. The
conductor layer has a predetermined circuit pattern. The resin
insulation layer includes a cured coating of the thermosetting
resin composition according to the first embodiment of the present
invention. The conductor layer and the resin insulation layer are
alternately provided on the inner layer circuit substrate. The
resin insulation layer has a boundary face which has a microscopic
concave-convex roughened surface and to which the conductor layer
is bonded.
[0022] According to a fourth embodiment of the present invention, a
multilayer printed wiring board includes an inner layer circuit
substrate, a conductor layer, and a resin insulation layer. The
conductor layer has a predetermined circuit pattern. The resin
insulation layer includes a dry film according to the above second
embodiment of the invention. The conductor layer and the resin
insulation layer are alternately provided on the inner layer
circuit substrate. The resin insulation layer has a boundary face
which has a microscopic concave-convex roughened surface and to
which the conductor layer is bonded.
[0023] According to a fifth embodiment of the present invention, a
thermosetting resin composition includes an epoxy resin (A) being
liquid at 20.degree. C. having a plurality of epoxy groups in a
molecule, an epoxy resin (B) being solid at 40.degree. C. having at
least three epoxy groups in a molecule, and an epoxy resin (C)
being solid at 20.degree. C. and liquid at 40.degree. C. having a
plurality of epoxy groups in a molecule. A ratio of mass of the
epoxy resin (A) to a sum of mass of the epoxy resin (B) and mass of
the epoxy resin (C) is about 1:1 to about 1:10, and a ratio of the
mass of the epoxy resin (B) to the mass of the epoxy resin (C) is
about 1:0.5 to about 1:2.
[0024] The embodiments will now be described with reference to the
accompanying drawings, wherein like reference numerals designate
corresponding or identical elements throughout the various
drawings.
[0025] In the case of containing the specific compounding ratio in
a combination of (A) an epoxy resin being liquid at 20.degree. C.
having an epoxy group of two or more in a molecule, (B) a solid
epoxy resin being solid at 40.degree. C. having an epoxy group of
three or more in a molecule and (C) a semisolid epoxy resin being
solid at 20.degree. C. and liquid at 40.degree. C. having an epoxy
group of two or more in a molecule, it is most suitable for an
interlayer insulation layer of a multilayer printed wiring board
that exhibits excellent adhesion to a base material and a
conductor, the cured coatings exhibits a relatively low coefficient
of thermal expansion, peel strength (peeling strength) of a
conductor layer formed by plating is high, and posses both high
heat resistance and roughened properties by roughening treatment.
Namely, in the case of the combination of a liquid epoxy resin with
a two functional group (A) and a solid epoxy resin with a three or
more functional group (B), when the compounding ratio of liquid
epoxy resin (A) is high, viscosity upon coating a resin composition
onto a base material becomes high, and a resin soaks a lot in
lamination onto a base material as a dry film. Reversely when the
compounding ratio of solid epoxy resin (B) is high, a sufficient
flexibility of a dry coating is not obtained, cracks and powder
dropping occur in the dry coating, peeling and breakage take place
in measuring adhesion strength by an Erichsen test. Further, in
lamination onto a circuit substrate, there is a tendency that no
sufficient flowability for a resin composition to be filled in a
via hole and a through-hole is obtained. The studies of the present
inventors have revealed that when in addition to the liquid epoxy
resin with a two functional group (A) and solid epoxy resin with a
three or more functional group (B), a semisolid epoxy resin being
solid at 20.degree. C. and liquid at 40.degree. C. having an epoxy
group of two or more in a molecule (C) is used in combination of
the specific compounding ratio, there is no problem described
above, the resulting thermosetting resin composition exhibits
excellent adhesion to a base material and a conductor, the cured
coating maintains a relatively low coefficient of thermal
expansion, peel strength (peeling strength) of a conductor layer
formed by plating is high, and an interlayer insulation layer with
excellent insulation reliability can be formed. Further, by being
mixed with a thermoplastic resin (F), detachment of fillers becomes
easy in roughening treatment, a stable roughed surface can be
formed, and also peel strength of a plated conductor layer is high
due to the anchor effect, and a multilayer printed wiring board
that an interlayer insulation layer with excellent heat resistance,
electrical insulation properties and the like is formed can be
produced.
[0026] By using the thermosetting resin composition according to
the embodiment of the present invention or dry film thereof in a
buildup method that a conductor circuit layer and an insulation
layer are alternately built up, it is possible to produce a
multilayer printed wiring board that peel strength of a plated
conductor layer is high, no crack is generated by a reliability
test such as thermal cycle, and an interlayer insulation layer with
excellent heat stability and electrical insulation properties is
formed.
[0027] Hereinafter, each constituent of the thermosetting rein
composition according to an embodiment of the present invention
will be explained in detail.
[0028] First, as an epoxy resin, as described above, it is
necessary to use in combination of (A) an epoxy resin being liquid
at 20.degree. C. having an epoxy group of two or more in a
molecule, (B) a solid epoxy resin being solid at 40.degree. C.
having an epoxy group of three or more in a molecule and (C) a
semisolid epoxy resin being solid at 20.degree. C. and liquid at
40.degree. C. having an epoxy group of two or more in a molecule.
Here, a determination method of "being liquid" in the present
specification is explained.
[0029] Determination of liquid form is conducted in accordance with
"Confirmation Method of Liquid Form" in Exhibit No. 2 of
ministerial ordinance on test of dangerous substance and aspect
(Ministry of Home Affairs Ordinance No. 1, 1989). The contents of
the "Confirmation Method of Liquid Form" in Exhibit No. 2 are
incorporated herein by reference in their entirety.
(1) Apparatus
[0030] Constant-temperature bath: one equipped with a stirrer,
heater, thermometer, automatic temperature regulator (capable of
temperature control in .+-.0.1.degree. C.) having a depth of 150 mm
or more is used.
[0031] Additionally, for all the determinations of the epoxy resins
used in Examples described below, a low temperature
constant-temperature bath (Yamato Scientific Co., Ltd.; BU300 type)
and Thermomate, a constant-temperature apparatus of input type
(BF500 type) are used in combination, about 22 liters of tap water
is put in the low temperature constant-temperature bath (BU300
type), a switch of Thermomate (BF500 type) equipped thereto is
turned on, which is set to a preset temperature (20.degree. C. or
40.degree. C.) and water temperature is finely adjusted to the
preset temperature .+-.0.1.degree. C. by Thermomate (BF500 type),
but any apparatus capable of similar adjustment can be used.
Test Tube:
[0032] As test tubes shown in FIGS. 2A and 2B, they are made of
transparent glass having a flat bottom cylindrical shape of 30 mm
in inner diameter and 120 mm in height where gauge lines 31, 32 are
given each at heights of 55 mm and 85 mm from the bottom, a test
tube for determination of liquid form 30a whose opening of a test
tube is sealed with a rubber plug 33a, and a test tube for
measuring temperature 30b of the same size being provided with the
same gauge lines whose opening is sealed with a rubber plug 33b
having a hole bored for inserting and supporting a thermometer at
the center and having a thermometer 34 inserted in the rubber plug
33b are used. Hereinafter, a gauge line at a height of 55 mm from
the bottom is called "A line", and a gauge line at a height of 85
mm from the bottom is called "B line."
[0033] As a thermometer 34, one for measuring a solidification
point (SOP-58 scale ranges, 20 to 50.degree. C.) specified by JIS
B7410 (1982) "Thermometer made of glass for testing petrochemicals"
is used, but one capable of measurement in a temperature range of 0
to 50.degree. C. may be enough. The contents of JIS B7410 (1982)
"Thermometer made of glass for testing petrochemicals" are
incorporated herein by reference in their entirety.
(2) Implementation Procedure of Test
[0034] Samples left at a temperature of 20.+-.5.degree. C. under
atmospheric pressure for more than 24 hours are put in a test tube
for determination of liquid form 30a shown in FIG. 2A and a test
tube for measuring temperature 30b shown in FIG. 2B each up to A
line. The two test tubes 30a and 30b are erected for B line to be
under the water surface in a low temperature constant-temperature
bath and allowed to stand still. A thermometer is set for its
bottom edge to be 30 mm under the A line.
[0035] After a sample temperature reaches a preset temperature
.+-.0.1.degree. C., the condition is kept as it is for 10 minutes.
After 10 minutes, the test tube for determination of liquid form
30a is taken out from the low temperature constant-temperature
bath, it is immediately placed horizontally on a horizontal test
table, a time that a front edge of liquid level inside the test
tube moves from A line to B line is measured with a stopwatch and
recorded. The sample is determined at a preset temperature as
liquid form when the time measured is within 90 seconds, and as
solid form when the time measured exceeds 90 seconds.
[0036] As the epoxy resin being liquid at 20.degree. C. having an
epoxy group of two or more in a molecule (A), there are listed a
bisphenol-A type epoxy resin, bisphenol-F type epoxy resin, phenol
novolac type epoxy resin, tert-butyl-catechol type epoxy resin,
glycidyl amine type epoxy resin, aminophenol type epoxy resin,
alicyclic epoxy resin and the like. Additionally, it goes without
saying that an epoxy resin of component (A) may be liquid at a
temperature of less than 20.degree. C. Further, the epoxy resin is
preferably an aromatic epoxy resin from the viewpoint of preferable
physical properties of the cured material. Additionally, in the
present specification, an aromatic epoxy resin means an epoxy resin
having an aromatic skeleton in a molecule. Hence, the component (A)
is more preferably "an aromatic epoxy resin being liquid at
20.degree. C. having an epoxy group of two or more in a molecule."
These epoxy resins may be used alone or in combination of two kinds
or more.
[0037] As the solid epoxy resin being solid at 40.degree. C. having
an epoxy group of three or more in a molecule (B), there are listed
a naphthalene type epoxy resin such as EXA4700 manufactured by DIC
Corporation (four functional naphthalene type epoxy resin) and
NC-7000 manufactured by Nippon Kayaku Co., Ltd. (multifunctional
solid epoxy resin containing naphthalene skeleton); an epoxidized
product of the condensate of phenols with aromatic aldehyde
containing a phenolic hydroxyl group (trisphenol type epoxy resin)
such as EPPN-502H manufactured by Nippon Kayaku Co., Ltd.
(trisphenol epoxy resin); a dicyclopentadiene aralkyl type epoxy
resin such as Epikuron HP-7200H manufactured by DIC Corporation
(multifunctional solid epoxy resin containing a dicyclopentadiene
skeleton); a biphenyl aralkyl type epoxy resin such as NC-3000H
manufactured by Nippon Kayaku Co., Ltd. (multifunctional solid
epoxy resin containing a biphenyl skeleton); a novolac type epoxy
resin such as Epikuron N660, Epikuron N690 manufactured by DIC
Corporation and EOCN-104S manufactured by Nippon Kayaku Co., Ltd.;
and tris(2,3-epoxypropyl)isocyanurate such as TEPIC manufactured by
Nissan Chemical Industries, Ltd. These epoxy resins may be used
alone, or in combination of two kinds or more thereof. In
particular, to provide a low thermal expansion, an epoxy resin
containing a naphthalene skeleton is preferably used.
[0038] As the semisolid epoxy resin being solid at 20.degree. C.
and liquid at 40.degree. C. having an epoxy group of two or more in
a molecule (C), there are listed a bisphenol-A type epoxy resin
such as Epikuron 860, Epikuron 900-1M, Epikuron EXA-4816, Epikuron
EXA-4822 manufactured by DIC Corporation, Araldite AER280
manufactured by Asahi-Ciba Co., Ltd., Epotohto YD-134 manufactured
by Tohto Kasei Co., Ltd., JER834, JER872 manufactured by Japan
Epoxy Resins Co., Ltd., and ELA-134 manufactured by Sumitomo
Chemical Co., Ltd.; a naphthalene type epoxy resin such as Epikuron
HP-4032 manufactured by DIC Corporation; and a phenol novolac type
epoxy resin such as Epikuron N-740 manufactured by DIC Corporation.
These epoxy resins may be used alone, or in combination of two
kinds or more thereof.
[0039] In the embodiment of the present invention, it is desirable
that the compounding ratio of three kinds of epoxy resins used in a
composition of the (A) an epoxy resin being liquid at 20.degree. C.
having an epoxy group of two or more in a molecule, (B) solid epoxy
resin being solid at 40.degree. C. having an epoxy group of three
or more in a molecule, and (C) semisolid epoxy resin being solid at
20.degree. C. and liquid at 40.degree. C. having an epoxy group of
two or more in a molecule is (A):(B+C)=about 1:1 to 1:10,
preferably about 1:2 to 1:10, and (B):(C =about 1:0.5 to about 1:2
in mass ratio. Further, the compounding ratio of the liquid epoxy
resin (A) and solid epoxy resin (B) is desirably (A):(B)=1:0.5 to
1:5 in mass ratio. When the liquid epoxy resin (A) is too high
exceeding the ratio, viscosity of a resin composition becomes high,
and a resin soaks a lot in lamination onto a base material as a dry
film. On the other hand, when the solid epoxy resin (B) is too high
exceeding the ratio, sufficient flexibility of a dry coating is not
obtained, cracks and powder dropping occur in the dry coating,
peeling and breakage take place in measuring adhesion strength by
an Erichsen test. Further, when the semisolid epoxy resin (C) is
outside the ratio, a problem resulting from use of the liquid epoxy
resin groups (A) and solid epoxy resin (B) tends to arise.
Additionally, since the liquid epoxy resin (A) contributes to
improvement on adhesion of the cured coating obtained and the solid
epoxy resin (B) contributes to an increase in glass transition
point, by adjusting these ratios, the balance of the
characteristics can be adjusted.
[0040] As the epoxy curing agent (D), various epoxy resin curing
agents conventionally known or epoxy resin curing accelerators can
be compounded. For example, there can be used a phenol resin,
imidazole compound, acid anhydride, aliphatic amine, alicylic
polyamine, aromatic polyamine, tertiary amine, dicyanediamide,
guanidines, or epoxy adducts thereof, micro-encapsulated materials,
and also organic phosphine series compounds such as triphenyl
phosphine, tetraphenyl phosphonium and tetraphenyl borate, DBU or
its derivatives, regardless of any curing agent or curing
accelerator, well-known ones may be used alone or in combination of
two kinds or more. These epoxy curing agents are preferably
compounded in a range of 0.1 to 50 parts by mass relative to the
total amount of 100 parts by mass of the epoxy resins (A) to (C).
When the compounding amount is less than the range, curing becomes
insufficient, whereas even when a large amount exceeding the range
is compounded, no accelerating effect on curing is increased, so it
is not preferable because a problem that heat resistance and
mechanical strength deteriorate tends to arise.
[0041] Among the epoxy curing agents, a phenol resin and an
imidazole compound are preferable. As the phenol resin, there can
be used well-known ones such as a phenol novolac resin, alkyl
phenol novolac resin, bisphenol-A novolac resin, dicyclopentadiene
type phenol resin, Xylok type phenol resin, terpene-modified phenol
resin and polyvinyl phenols, alone or in combination of two kinds
or more thereof.
[0042] Further, an imidazole compound is preferable from the points
that reaction is mild in a temperature region (80.degree. C. to
130.degree. C.) in drying solvents in a composition and reaction
can be sufficiently carried out in a temperature region
(150.degree. C. to 200.degree. C.) in curing, and physical
properties of the cured material can be sufficiently exhibited. The
imidazole compound is also preferable from the point that it is
excellent in adhesion to a copper circuit and copper foil. As a
specific example of particularly preferable ones, there are
listed
2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole,
2-phenyl-4-methylimidazole, bis(2-ethyl-4-methyl-imidazole),
2-phenyl-4-methyl-5-hydroxymethylimidazole,
2-phenyl-4,5-dihydroxymethylimidazole, triazine-added type
imidazole and the like, they can be used alone or in combination of
two kinds or more thereof.
[0043] Next, as the filler (E), all inorganic fillers and organic
fillers conventionally known can be used, it is not particularly
limited, but since operation for forming a minute concave-convex
roughened surface on the surface of a cured coating by roughening
treatment is mainly resulted from that a roughening agent
penetrates into a boundary face between a cured coating and a
filler, and fillers on the surface of the cured coating drops out,
so that an inorganic filler having excellent affinity with a
roughening agent is preferable. As an inorganic filler, there are
listed, for example, body pigments such as barium sulfate, barium
titanate, amorphous silica, crystalline silica, molten silica,
spherical silica, talc, clay, magnesium carbonate, calcium
carbonate, aluminum oxide, aluminum hydroxide, silicon nitride and
aluminum nitride, and metal powders such as copper, tin, zinc,
nickel, silver, palladium, aluminum, iron, cobalt, gold and
platinum. These inorganic fillers suppress shrinkage in curing of
coatings, and contribute to improvement of characteristics such as
adhesion and hardness in addition to an operation for forming a
minute concave-convex roughened surface by roughening treatment.
Among these inorganic fillers, silica and barium sulfate that are
hardly damaged by a roughening agent are preferable, in particular,
spherical silica is preferable from the point that it can be
compounded in a high ratio in a composition. The average particle
diameter of a filler is preferably 3 .mu.m or less, and further
preferably 1 .mu.m or less.
[0044] The compounding amount of filler (E) is 40 to 200 parts by
mass relative to the total amount of 100 parts by mass of the epoxy
resins (A) to (C), preferably, the ratio is suitably 50 to 150
parts by mass. When the compounding amount of the filler is less
than the range, it becomes difficult to form an excellent minute
concave-convex roughened surface, on the other hand, when exceeding
the range, it is not preferable because flowability of a
composition becomes bad.
[0045] The thermosetting composition according to the embodiment of
the present invention can further contains, for improving
mechanical strength of the cured coating obtained, a thermoplastic
resin (F) whose glass transition temperature is 100.degree. C. or
more, for example, a thermoplastic polyhydroxypolyether resin
described below, a phenoxy resin being the condensate of
epichlorohydrine with various kinds of two-functional phenol
compounds, or a phenoxy resin that a hydroxyl group of hydroxyether
part present in the skeleton is esterified using various acid
anhydrides or acid chlorides, polyvinyl acetal resin, polyamide
resin, polyamideimide resin and the like, which are used alone or
in combination of two kinds or more thereof. When the glass
transition temperature of thermoplastic resin (F) is less than
100.degree. C., the mechanical strength of the cured material is
not sufficient, and inorganic fillers tend to precipitate on the
surface of the cured material after roughening, so it becomes
difficult to obtain a sufficient peel strength of a plated
conductor layer. The glass transition temperature is determined
according to a method described in JIS (Japanese Industrial
Standards) K7197. The contents of JIS K7197 are incorporated herein
by reference in their entirety. Additionally, even in the case
where no glass transition temperature is actually observed because
the glass transition temperature is higher than decomposition
temperature, it is included in the definition of "glass transition
temperature is 100.degree. C. or more" in the embodiment of the
present invention. Additionally, the decomposition temperature is
defined as a temperature when a mass decreasing rate is 5% in
measurement according to a method described in JIS K7120. The
contents of JIS K7120 are incorporated herein by reference in their
entirety.
[0046] As a specific example of phenoxy resins, there are listed
FX280, FX293 manufactured by Tohto Kasei Co., Ltd., YX8100, YL6954,
YL6974 manufactured by Japan Epoxy Resins Co., Ltd., and the like.
As a specific example of polyvinyl acetal resins, S-LEC KS-series
manufactured by Sekisui Chemical Co., Ltd. are listed, as an
polyamide resin, KS 5000 series manufactured by Hitachi Chemical
Co., Ltd. and BP series manufactured by Nippon Kayaku Co., Ltd. are
listed, further, as an polyamideimide resin, KS 9000 series
manufactured by Hitachi Chemical Co., Ltd. are listed.
[0047] Among the thermoplastic resins, a thermoplastic
polyhydroxypolyether resin having a fluorene skeleton is
preferable. Since the thermoplastic polyhydroxypolyether resin has
a high glass transition point because of having a fluorene skeleton
and is excellent in heat resistance, as well as it maintains a low
coefficient of thermal expansion due to epoxy resins (A) to (C), it
maintains its glass transition point, the resulting cured coating
has a good balance of both low coefficient of thermal expansion and
high glass transition point. Further, since a thermoplastic
polyhydroxypolyether resin has a hydroxyl group, it shows excellent
adhesion to a base material and a conductor, as well as the cured
coating obtained is hardly damaged by a roughening agent, but a
roughening agent in a form of aqueous solution is easy to penetrate
into the boundary face between the cured coating and filler,
fillers on the surface of the cured coating tend to drop out by
roughening treatment, resulting in easily forming an excellent
roughened surface.
[0048] As the thermoplastic polyhydroxypolyether resin having a
fluorene skeleton, for example, a thermoplastic
polyhydroxypolyether resin expressed by the following general
formula (1) can be appropriately used.
##STR00001##
[0049] In the above general formula (1), X represents the following
general formula (2) or (3), the ratio of the general formula (3)
relative to the total X in the general formula (1) is 8% or more, Z
is a hydrogen atom or a glycidyl group, and n is an integer of 21
or more.
##STR00002##
[0050] In the above general formula (2), R.sup.1 and R.sup.2 are
selected from a hydrogen atom, an alkyl group having carbon numbers
of 1 to 5, and a halogen atom, Y is any one of --SO.sub.2--,
--CH.sub.2--, --C(CH.sub.3).sub.2-- or --O--, and m is 0 or 1.
R.sup.1 and R.sup.2 may be the same or different.
##STR00003##
[0051] The molecular weight of the thermoplastic
polyhydroxypolyether resin having a fluorene skeleton is preferably
in a range of 5,000 to 100,000 (weight average molecular weight
measured by gel permeation chromatography (GPS) in terms of
standard polystyrene). When the molecular weight is less than
5,000, thermoplasticity is lost, whereas when it exceeds 100,000,
solution viscosity when it is dissolved in a solvent is too high,
it is not preferable because it becomes difficult to add a lot of
fillers.
[0052] A halogen may be introduced in the thermoplastic
polyhydroxypolyether resin having a fluorene skeleton for providing
flame resistance. In the case of providing flame resistance with a
halogen, when the content of halogen is less than 5% by mass, it is
difficult to provide a sufficient flame resistance, on the other
hand, no further improvement is observed even when the
concentration is more than 40% by mass, so it is practical that the
content of halogen is controlled in a range of 5 to 40% by mass.
The kind of halogen may be any one, but from the viewpoint of
commercial production, it is preferable to utilize a commercially
available bromide compound, chloride compound or fluorine
compound.
[0053] As a process for producing the thermoplastic
polyhydroxypolyether resin having a fluorene skeleton, a method of
direct reaction of divalent phenols with epichlorohydrine, and a
method of addition polymerization reaction of diglycidyl ether of
divalent phenols with divalent phenols are known, and either
production method may be adopted for the resin. Additionally,
regarding a process for producing the thermoplastic
polyhydroxypolyether resin, it is described in detail in Japanese
Unexamined Patent Publication 11-269264 as a reference.
[0054] The compounding amount of the thermoplastic resin (F) in the
thermosetting resin composition according to the embodiment of the
present invention is preferably 5 to 50 parts by mass relative to
the total amount of 100 parts by mass of the epoxy resins (A) to
(C), and preferably 10 to 40 parts by mass. When the compounding
amount of the thermoplastic resin (F) is outside the range, it
becomes difficult to obtain a uniform roughened surface
condition.
[0055] Further, in the thermosetting resin composition according to
the embodiment of the present invention, a polyimide resin,
polyphenol resin, polyisocyanate resin, polyester resin,
thermosetting type polyphenylene ether resin and the like may be
added.
[0056] Further, the thermosetting resin composition according to
the embodiment of the present invention can contain an organic
solvent as needed. As an organic solvent, there can be used
ordinary solvents, for example, ketones such as acetone, methyl
ethyl ketone and cyclohexanone; ester acetates such as ethyl
acetate, butyl acetate, cellosolve acetate, propylene glycol
monomethyl ether acetate and carbitol acetate; cellosolves such as
cellosolve and butyl cellosolve; carbitols such as carbitol and
butyl carbitol; aromatic hydrocarbons such as toluene and xylene;
dimethylformamide, dimethylacetamide and the like, alone or in
combination of two kinds or more thereof.
[0057] The thermosetting resin composition according to the
embodiment of the present invention can further use, according to
need, well-known coloring agents such as phthalocyanine blue,
phthalocyanine green, iodine green, disazo yellow, crystal violet,
titanium oxide, carbon black and naphthalene black; well-known
thickner such as asbestos, olben, benton and finely-divided silica;
defoaming agents and/or leveling agents of such as silicone series,
fluorine series and polymer series; adhesion providing agents such
as thiazole series, triazole series, silane coupling agent; and
well-known additives of such as titanate series and aluminum
series.
[0058] Although the thermosetting resin composition according to
the embodiment of the present invention makes the formation of
roughened surface easy by containing fillers (E), deterioration of
surface smoothness and the like occurs easily. Regarding this
point, the embodiment of the present invention can prevent
deterioration of surface smoothness by compounding a defoaming
agent and/or leveling agent (G) particularly among the additives,
and also prevent deterioration of interlayer insulation due to
voids and pinholes.
[0059] As a specific example of the defoaming agent and/or leveling
agent (G), as a commercially available defoaming agent composed of
non-silicone series foam-breaking polymer solution, BYK
(trademark)-054, -055, -057, -1790, and the like manufactured by
Big Chemie Japan Co., Ltd. are listed, and as a silicone series
defoaming agent, BYK (trademark)-063,-065, -066N, -067A, -077
manufactured by Big Chemie Japan Co., Ltd. and KS-66 (product
name), and the like manufactured by Shin-Etsu Chemical Co., Ltd.
are listed.
[0060] The compounding amount of such defoaming agent and/or
leveling agent (G) is 5 parts by weight or less relative to total
amount of 100 parts by mass of the epoxy resins (A) to (C) and
thermoplastic resin (F), preferably, 0.01 to 5 parts by weight is
suitable.
[0061] The mode of the thermosetting resin composition according to
the embodiment of the present invention may be provided as a
coating material whose viscosity is suitably adjusted, or as a dry
film that a thermosetting resin composition is coated on a
supporting base film and a solvent is dried. It may further be
provided as a prepreg sheet that the composition is coated on
and/or immersed in a fibrous base material of sheet form such as
glass cross, glass, and aramid non-woven and half cured. As the
supporting base film, there are listed polyolefin such as
polyethylene and polyvinyl chloride, polyesters such as
polyethylene terephthalate, polycarbonate, polyimide, further,
exfoliate paper, metal foils such as copper foil and aluminum foil.
Additionally, the supporting base film may be subjected to mad
treatment, corona treatment or the like.
[0062] A coating material, dry film or prepreg using the
thermosetting resin composition may be directly coated on an inner
layer circuit substrate that a circuit was formed, then dried and
cured, or it may be heat-laminated with a dry film and formed
integrally, thereafter cured in an oven, or cured by a hot plate
press. In the case of prepreg, it is layered on an inner layer
circuit substrate, sandwiched by metal plates via a release film,
pressured and heated to be subjected to pressing.
[0063] Among the processes, a method of lamination or hot plate
press is preferable because a minute concavity and convexity by an
inner circuit is eliminated in heat melting, cured as it is to
finally give a multilayer substrate of flat surface condition.
Further, when a base material that an inner layer circuit was
formed and a film or prepreg of the thermosetting resin composition
according to the embodiment of the present invention are laminated
or hot plate pressed, a copper foil or a base material that a
circuit was formed can be laminated at the same time.
[0064] The substrate thus obtained is bored by a semiconductor
laser such as CO.sub.2 laser and UV-YAG laser, or by drill. The
hole may be either a through-hole aiming at conducting the front
and back of the substrate, or a partial hole (conformal via) aiming
at conducting a circuit of an inner layer and a circuit on the
surface of an interlayer insulation layer.
[0065] After boring, to remove residue (smear) present in the inner
wall and bottom of a hole and to exhibit an anchor effect on a
conductor layer (metal plating formed thereafter), for forming a
minute concave-convex roughened surface on the surface, it is
carried out with a commercially available desmear liquid
(roughening agent) or a roughening agent containing an oxidant such
as permanganate, bichromate, ozone, hydrogen peroxide/sulfuric
acid, and nitric acid at the same time.
[0066] Next, after forming a hole that residue was removed by a
desmear liquid and a coating surface that a minute concave-convex
roughened surface was generated, a circuit is formed by a
subtractive method, semi-additive method or the like. In any
method, after carrying out nonelectrolytic plating or electrolytic
plating, or both plating, for removing stress of metal and
improving strength, heat treatment called anneal may be carried out
at about 80 to 180.degree. C. for 10 to 60 minutes.
[0067] The metal plating used here is not particularly limited, and
copper, tin, solder, nickel and the like, or in combination of a
plurality thereof can be used. Further, plating used here can be
replaced by sputtering of metal, and the like.
EXAMPLES
[0068] Hereinafter, Examples, Comparative example and Test example
of the present invention will be explained, but the present
invention is not limited to the following Examples. Additionally,
hereinafter, "part" and "%" are all based on mass unless otherwise
specified.
Examples 1 to 6 and Comparative Examples 1 to 3
[0069] Each component was compounded according to a formulation
shown in Table 1 below, kneaded and dispersed by a three-roll mill
to obtain a thermosetting resin composition that viscosity was
adjusted to 20 dPas .+-.10 dPas (rotational viscometer 5 rpm,
25.degree. C.).
TABLE-US-00001 TABLE 1 Example Comparative example Composition
(part by mass) 1 2 3 4 5 6 1 2 3 Liquid epoxy Epicoat 807 *.sup.1
10 5 10 15 20 10 10 5 30 resin (A) Solid epoxy Epikuron N-690
*.sup.2 20 15 20 6 resin (B) Epikuron N-660 *.sup.3 25 25 10 20 5
Semisolid Epikuron 860 *.sup.4 20 15 10 20 epoxy resin (C) Epikuron
N-740 *.sup.5 25 25 30 4 Phenol series LA-7052-60M *.sup.6 25 25
curing agent HF1M *.sup.7 20 20 20 20 20 20 20 Imidazole series
Curezole 2PHZ *.sup.8 5 5 5 5 3 curing agent Thermoplastic
EX293AM40 *.sup.9 8 10 15 10 20 20 8 10 15 resin Inorganic filler
SO--C2 *.sup.10 60 100 100 100 100 100 60 100 100 Organic solvent
Cyclohexanone 20 30 30 30 30 30 20 30 30 Methyl ethyl ketone 20 30
30 30 30 30 20 30 30 A:B 1:2 1:5 1:2.5 1:1 1:0.5 1:2 1:2 1:1 1:0.2
B:C 1:1 1:1 1:1 1:1 1:1 1:1 -- 1:6 1:0.66 A:(B + C) 1:4 1:10 1:5
1:2 1:1 1:4 1:2 1:7 1:0.33 Adhesion strength .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. x .smallcircle. .smallcircle. Soaking .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. x x Remarks *.sup.1 Bisphenol-A type
liquid epoxy resin manufactured by DIC Corp. *.sup.2 Solid novolac
type epoxy resin manufactured by DIC Corp. *.sup.3 Solid novolac
type epoxy resin manufactured by DIC Corp. *.sup.4 Semisolid
bisphenol-A type epoxy resin manufactured by DIC Corp. *.sup.5
Semisolid phenol novolac type epoxy resin manufactured by DIC Corp.
*.sup.6 MEK vanish of Phenolite LA-7052-60M manufactured by DIC
Corp., phenol novolac resin containing triazine structure (solid
content 60%) *.sup.7 Novolac phenol resin manufactured by Meiwa
Plastic Industries Ltd. *.sup.8 Imidazole derivative manufactured
by Shikoku Chemicals Corp. *.sup.9 Thermoplastic
polyhydroxypolyether resin having fluorene skeleton manufactured by
Tohto Kasei Corp. *.sup.10 Spherical silica manufactured by Admatec
GmbH.
Production of Adhesion Film
[0070] The thermosetting resin compositions thus obtained were each
coated on a PET film (Toray Industries Inc., Luminar 38R75: 38
.mu.m) using a bar coater for the membrane thickness of film to be
63 .mu.m after drying, and dried at 110.degree. C. for 15 minutes,
thereby to obtain an adhesion film.
Test Example
[0071] The adhesion film was heat-laminated on a buffed-finish
copper plate of 0.8 mm thickness using a vacuum laminator (MEIKI
Corporation, MVLP-500) under the conditions of 5 kgf/cm.sup.2,
120.degree. C., 1 minute and 1 Torr, subsequently, leveled by a hot
plate press under the conditions of 10 kgf/cm.sup.2, 130.degree. C.
and 1 minute, then cured in a hot air circulating type dryer under
the condition of 150.degree. C..times.30 minutes.
[0072] The sample obtained was measured for adhesion strength, and
determined on the basis of the following standard. Further, the
sample obtained was observed for soaking of resin, and determined
on the basis of the following standard. The results are shown in
Table 1 all together
Adhesion Strength
[0073] In a test carried out using an Erichsen tester (Erichsen AG,
type 202-C) at a test speed of 7 m/min, when the extrusion length
of an extrusion pin when detachment or crack occurs is 3 mm or
less, it was denoted as x, and when exceeding 3 mm, it was denoted
as o.
Soaking of Resin
[0074] When soaking was less than 5 mm, it was denoted as o, and
when 5 mm or more, it was denoted as x.
[0075] As is clear from the results shown in the above Table 1, in
each Example using the thermosetting resin composition according to
the embodiment of the present invention, there was no soaking of
resin, and high adhesion strength was shown. In contrast, in
Comparative example 1 where a thermosetting resin composition not
containing a semisolid epoxy resin was used, adhesion strength was
inferior. Further, in Comparative example 2 and in Comparative
example 3, although there was no serious problem in adhesion
strength because the composition contains a semisolid epoxy resin,
soaking of resin took places because the compounding ratio of
liquid epoxy resin was high.
[0076] The thermosetting resin composition according to the
embodiment of the present invention exhibits excellent adhesion to
a base material and a conductor, the cured coatings exhibits a
relatively low coefficient of thermal expansion, and also peel
strength (peeling strength) of a conductor layer formed by plating
is high, and posses both high heat resistance and roughened
properties by roughening treatment, so that it is useful for
forming an interlayer insulation layer of a multilayer printed
wiring board by a buildup method where a conductor circuit layer
and an insulation layer are alternately built up, and also useful
for producing a dry film or prepreg for an interlayer insulating
material.
[0077] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *