U.S. patent application number 15/124469 was filed with the patent office on 2017-01-19 for photosensitive resin composition, solder resist composition, and covered-printed wiring board.
The applicant listed for this patent is GOO CHEMICAL CO., LTD.. Invention is credited to Yoshio SAKAI.
Application Number | 20170017152 15/124469 |
Document ID | / |
Family ID | 54192555 |
Filed Date | 2017-01-19 |
United States Patent
Application |
20170017152 |
Kind Code |
A1 |
SAKAI; Yoshio |
January 19, 2017 |
PHOTOSENSITIVE RESIN COMPOSITION, SOLDER RESIST COMPOSITION, AND
COVERED-PRINTED WIRING BOARD
Abstract
This photosensitive resin composition includes: (A) a
photopolymerizable compound including at least one of a
photopolymerizable monomer and a photopolymerizable oligomer; (B)
titanium dioxide; and (C) a photopolymerization initiator. The
component (C) includes (C1) an acylphosphine oxide-containing
photopolymerization initiator and (C2) a phenylglyoxylic
acid-containing photopolymerization initiator.
Inventors: |
SAKAI; Yoshio; (Shiga,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GOO CHEMICAL CO., LTD. |
Kyoto |
|
JP |
|
|
Family ID: |
54192555 |
Appl. No.: |
15/124469 |
Filed: |
August 17, 2015 |
PCT Filed: |
August 17, 2015 |
PCT NO: |
PCT/JP2015/004080 |
371 Date: |
September 8, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 1/02 20130101; H05K
2201/068 20130101; G03F 7/029 20130101; G03F 7/0388 20130101; G03F
7/0385 20130101; G03F 7/038 20130101; G03F 7/20 20130101; G03F
7/2006 20130101; H05K 3/287 20130101; G03F 7/26 20130101; H05K
3/3452 20130101; H05K 3/282 20130101; H05K 2201/0166 20130101; G03F
7/0042 20130101; G03F 7/0043 20130101; G03F 7/031 20130101; H05K
1/0274 20130101; H05K 1/0353 20130101; G03F 7/322 20130101 |
International
Class: |
G03F 7/031 20060101
G03F007/031; G03F 7/038 20060101 G03F007/038; H05K 1/03 20060101
H05K001/03; G03F 7/26 20060101 G03F007/26; H05K 1/02 20060101
H05K001/02; G03F 7/004 20060101 G03F007/004; G03F 7/20 20060101
G03F007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 2014 |
JP |
PCT/JP2014/06157 |
Claims
1. A photosensitive resin composition comprising: (A) a
photopolymerizable compound including at least one of a
photopolymerizable monomer and a photopolymerizable oligomer; (B)
titanium dioxide; and (C) a photopolymerization initiator, the
component (C) including (C1) an acylphosphine oxide-containing
photopolymerization initiator and (C2) a phenylglyoxylic
acid-containing photopolymerization initiator.
2. The photosensitive resin composition according to claim 1,
wherein the component (A) includes (F1) a compound which contains a
carboxyl group.
3. The photosensitive resin composition according to claim 2,
wherein the component (F1) includes a (meth)acrylic copolymer.
4. The photosensitive resin composition according to claim 1,
wherein the component (A) includes a caprolactone-modified
(meth)acrylate monomer.
5. The photosensitive resin composition according to claim 1,
wherein the component (B) includes rutile titanium dioxide.
6. The photosensitive resin composition according to claim 1,
wherein the component (C1) includes a bisacylphosphine
oxide-containing photopolymerization initiator.
7. The photosensitive resin composition according to claim 1
comprising (D) an epoxy compound.
8. The photosensitive resin composition according to claim 7,
wherein the component (D) includes a crystalline epoxy compound
that has a melting point within a range of 130 to 160.degree.
C.
9. The photosensitive resin composition according to claim 7,
wherein: the component (D) includes at least one of triglycidyl
isocyanurate and a hydroquinone epoxy compound represented by
following formula (1); and R.sup.1, R.sup.2, R.sup.3, and R.sup.4
in the formula (1) are independently a methyl group, a hydrogen
atom, or a t-butyl group.
10. The photosensitive resin composition according to claim 1
further comprising (E) an antioxidant.
11. The photosensitive resin composition according to claim 10,
wherein the component (E) has a melting point within a range of 50
to 150.degree. C.
12. A solder resist composition containing the photosensitive resin
composition according to claim 1.
13. A covered-printed wiring board including: a printed wiring
board; and a solder resist layer covering the printed wiring board,
the solder resist layer containing a cured product of the solder
resist composition according to claim 12.
Description
TECHNICAL FIELD
[0001] The present invention relates to a photosensitive resin
composition, a solder resist composition and a covered-printed
wiring board, and specifically relates to a photosensitive resin
composition with photocurability, a solder resist composition
including the photosensitive resin composition, and a
covered-printed wiring board including a solder resist layer formed
with the solder resist composition.
BACKGROUND ART
[0002] In recent years, as a method for forming solder resist
layers on printed wiring boards for consumer use and industrial
use, a developable solder resist composition with excellent
resolution and dimensional accuracy has been widely used, instead
of a screen printing method, in order to increase the density of
wiring on the printed wiring board.
[0003] Additionally, in recent years, there is an increasing use of
optical elements, such as light-emitting diodes, mounted directly
on a printed wiring board covered with a solder resist layer,
wherein the light-emitting diodes are often used for: backlights in
liquid crystal displays for mobile terminals, personal computers,
and televisions; and light sources for lighting devices.
Furthermore, when titanium dioxide is contained in the solder
resist layer on the printed wiring board mounted with optical
elements, the solder resist layer is whitened and therefore light
emitted from optical elements is efficiently reflected at the
solder resist layer (see JP2012-78414A).
[0004] However, in a process of curing the solder resist
composition under exposure to light, titanium dioxide contained in
the solder resist composition may cause difficulty in curing of the
solder resist composition due to titanium dioxide reflecting or
absorbing light. Especially when the solder resist composition
contains a large amount of titanium dioxide, it is difficult for
the solder resist layer formed with the solder resist composition
to completely cure from a surface to a deep part. If the deep part
of the solder resist layer is not thoroughly cured, it is likely
for defects to occur, such as lowered resolution in development,
wrinkles on the solder resist layer caused by a difference in
curing shrinkages of the deep part and the surface of the solder
resist layer, and cracks on the solder resist layer when heated due
to a partial stress caused by a difference in thermal expansion
coefficients of the printed wiring board and the solder resist
layer.
SUMMARY OF INVENTION
[0005] The present invention has been made in light of the
above-described circumstances, and it is an object thereof to
provide, a photosensitive resin composition capable of forming a
cured product which is thoroughly cured from a deep part to a
surface by photocuring the photosensitive resin composition, a
solder resist composition including the photosensitive resin
composition, and a covered-printed wiring board including a solder
resist layer formed with the solder resist composition.
Solution to Problem
[0006] A photosensitive resin composition according to the present
invention includes: (A) a photopolymerizable compound including at
least one of a photopolymerizable monomer and a photopolymerizable
oligomer; (B) titanium dioxide; and (C) a photopolymerization
initiator. The component (C) includes (C1) an acylphosphine
oxide-containing photopolymerization initiator and (C2) a
phenylglyoxylate-containing photopolymerization initiator.
[0007] A solder resist composition according to the present
invention contains the photosensitive resin composition.
[0008] A covered-printed wiring board according to the present
invention includes: a printed wiring board; and a solder resist
layer covering the printed wiring board. The solder resist layer
includes a cured product of the solder resist composition.
[0009] According to the present invention, the photosensitive resin
composition capable of forming a cured product which is thoroughly
cured from a deep part to a surface by photocuring the
photosensitive resin composition can be provided.
DESCRIPTION OF EMBODIMENTS
[0010] An embodiment for implementing the present invention is now
described. It should be noted that in description from now on,
"(meth)acryl" means at least one of "acryl" and "methacryl". For
example, (meth)acrylate means at least one of acrylate and
methacrylate.
[0011] A photosensitive resin composition according to the present
embodiment includes (A) a photopolymerizable compound including at
least one of a photopolymerizable monomer and a photopolymerizable
oligomer (also referred to as a component (A) hereinafter); (B)
titanium dioxide (also referred to as a component (B) hereinafter);
and (C) a photopolymerization initiator (also referred to as a
component (C) hereinafter). The component (C) includes (C1) an
acylphosphine oxide-containing photopolymerization initiator and
(C2) a phenylglyoxylate-containing photopolymerization
initiator.
[0012] The photosensitive resin composition according to the
present embodiment can be cured under photoirradiation. For
example, a cured film containing a cured product of the
photosensitive resin composition can be obtained when the
photosensitive resin composition is formed into a film and then the
film of the photosensitive resin composition is irradiated with
light.
[0013] The photopolymerization initiator having light absorptivity
at a wavelength within a range of 380 to 420 nm can exhibit high
photoactivity in a system containing a large amount of titanium
dioxide. Since the component (C1) has light absorptivity at a
wavelength of about 400 nm, in principle, the photosensitive resin
composition containing the component (C1) is expected to have high
photocurability even when titanium dioxide is contained. However,
in reality, when the photosensitive resin composition contains both
of titanium dioxide and the component (C1), it is difficult to cure
the film of the photosensitive resin composition thoroughly under
photoirradiation. Depending on a concentration of the component
(C1) in the photosensitive resin composition, although a surface of
the photosensitive resin composition may be fully cured, a deep
part of the photosensitive resin composition may not be fully
cured, and vice versa.
[0014] However, in the present embodiment, since the component (C)
includes not only the component (C1) but also the component (C2),
the photosensitive resin composition can be thoroughly cured from
the surface to the deep part when the film of the photosensitive
resin composition is irradiated with light.
[0015] Therefore, in the present embodiment, when, for example, a
solder resist composition containing the photosensitive resin
composition is photocured to form a solder resist layer, the solder
resist layer can be thoroughly cured from the surface to the deep
part.
[0016] Note that, the photosensitive resin composition according to
the present embodiment is not limited to a use for the solder
resist composition. The photosensitive resin composition can be
applied, for example, for a photocurable printing ink.
[0017] The photosensitive resin composition according to the
present embodiment will be further described specifically
hereinafter.
[0018] The component (A) provides photocurability to the
photosensitive resin composition. The component (A) includes at
least one compound selected from a group consisting of the
photopolymerizable monomer and the photopolymerizable oligomer.
[0019] The photopolymerizable monomer contains, for example, an
ethylene-based unsaturated group. The photopolymerizable monomer
may include at least one compound selected from a group consisting
of, for example, monofunctional (meth)acrylates such as
2-hydroxyethyl (meth)acrylate and multifunctional (meth)acrylates
such as diethylene glycol di(meth)acrylate, trimethylolpropane
di(meth)acrylate, trimethylolpropane tri(meth)acrylate,
pentaerythritol tri(meth)acrylate, pentaerythritol
tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate,
dipentaerythritol hexa(meth)acrylate, and
.epsilon.-caprolactone-modified dipentaerythritol
hexa(meth)acrylate.
[0020] The photopolymerizable monomer preferably includes a
phosphorus-containing compound (a phosphorus-containing
photopolymerizable compound). In this case, flame retardancy of the
cured product of the photosensitive resin composition is improved.
The phosphorus-containing photopolymerizable compound may include
at least one compound selected from a group consisting of, for
example, 2-methacryloyloxy ethyl acid phosphate (for example, Light
Ester P-1M and Light Ester P-2M manufactured by Kyoeisha Chemical
Co., Ltd.), 2-acryloyloxy ethyl acid phosphate (for example, Light
Acrylate P-1A manufactured by Kyoeisha Chemical Co., Ltd.),
diphenyl-2-methacryloyloxy ethyl phosphate (for example, MR-260
manufactured by Daihachi Chemical Industry Co., Ltd.), and HFA
series manufactured by Showa Highpolymer K. K. (for example,
HFA-6003 and HFA-6007 which are products of an addition reaction of
dipentaerythritol hexaacrylate and HCA, and HFA-3003 and HFA 6127
which are products of an addition reaction of caprolactone-modified
dipentaerythritol hexaacrylate and HCA).
[0021] Examples of the photopolymerizable oligomer include a
prepolymer which is prepared by adding an ethylene-based
unsaturated group to a prepolymer obtained by polymerization of
photopolymerizable monomers, and oligo (meth)acrylate prepolymers
such as epoxy (meth)acrylates, polyester (meth)acrylates, urethane
(meth)acrylates, alkyd resin (meth)acrylates, silicone resin
(meth)acrylates, spiran resin (meth)acrylates.
[0022] The component (A) is especially preferred to include a
caprolactone-modified (meth) acrylate monomer such as
.epsilon.-caprolactone-modified pentaerythritol hexaacrylate. In
this case, the cured product of the photosensitive resin
composition is particularly effectively prevented from becoming
fragile and can gain flexibility.
[0023] The component (A) may also include photopolymerizable
carboxyl group-containing resin (hereinafter referred to as a
component (F1)) which contains a carboxyl group and a
photopolymerizable functional group. The photopolymerizable
functional group is, for example, an ethylene-based unsaturated
group. The component (F1) can provide the photosensitive resin
composition with not only photocurability but also developability
in an alkaline aqueous solution, i.e., alkali developability.
[0024] The component (F1) may include resin (hereinafter referred
to as first resin (a)), for example, having a structure resulting
from an addition reaction of at least one kind of a compound (a3)
selected from polycarboxylic acids and anhydrides thereof, and a
secondary hydroxyl group obtained from a reaction between an
ethylene-based unsaturated compound (a2), which contains a carboxyl
group, and at least one epoxy group in an epoxy compound (a1) which
contains two or more epoxy groups per molecule.
[0025] The epoxy compound (a1) may include at least one kind of
compound selected from a group consisting of, for example, cresol
novolak type epoxy resin, phenol novolak type epoxy resin,
bisphenol A type epoxy resin, bisphenol F type epoxy resin,
bisphenol A-novolak type epoxy resin, naphthalene type epoxy resin,
biphenyl type epoxy resin, biphenyl aralkyl type epoxy resin,
triglycidyl isocyanurate, and alicyclic epoxy resin.
[0026] The epoxy compound (a1) may include a polymer of an
ethylene-based unsaturated compound (p) which includes an epoxy
group-containing compound (p1). The ethylene-based unsaturated
compound (p) provided for a synthesis of the polymer may include
the epoxy group-containing compound (p1) alone or in combination
with an epoxy group-free compound (p2).
[0027] The epoxy group-containing compound (p1) may include a
compound selected from appropriate polymers and prepolymers.
Specifically, the epoxy group-containing compound (p1) may include
one or more kinds of compounds selected from a group consisting of
epoxy cyclohexyl derivatives of acrylic acid, epoxy cyclohexyl
derivatives of methacrylic acid, an alicyclic epoxy derivative of
acrylates, an alicyclic epoxy derivative of methacrylates,
.beta.-methyl glycidyl acrylate, and .beta.-methyl glycidyl
methacrylate. Especially, the epoxy group-containing compound (p1)
is preferred to include glycidyl (meth)acrylate, which is widely
used and easily obtained.
[0028] The epoxy group-free compound (p2) may be any compound as
long as it is polymerizable with the epoxy group-containing
compound (p1). The epoxy group-free compound (p2) may include one
or more kinds of compounds selected from a group consisting of, for
example, 2-(meth)acryloyloxyethyl phthalate,
2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate,
2-(meth)acryloyloxypropyl phthalate, benzyl (meth)acrylate,
neopentyl glycol benzoate (meth)acrylate, paracumyl phenoxyethylene
glycol (meth)acrylate, EO-modified cresol (meth)acrylate,
ethoxylated phenyl (meth)acrylate, nonylphenoxy polyethylene glycol
(meth)acrylate (polymerization degree n=2-17), ECH-modified phenoxy
(meth)acrylate, phenoxy diethylene glycol (meth)acrylate,
phenoxyethyl (meth)acrylate, phenoxy hexaethylene glycol
(meth)acrylate, phenoxy tetraethylene glycol (meth)acrylate,
tribromophenyl (meth)acrylate, EO-modified tribromophenyl (meth)
acrylate, EO-modified bisphenol A di(meth)acrylate, PO-modified
bisphenol A di(meth)acrylate, modified bisphenol A
di(meth)acrylate, EO-modified bisphenol F di(meth)acrylate,
ECH-modified phthalic acid di(meth)acrylate, trimethylolpropane
benzoate (meth)acrylate, EO-modified phthalic acid (meth)acrylate,
EO/PO-modified phthalic acid (meth)acrylate, vinylcarbazole,
styrene, N-phenylmaleimide, N-benzylmaleimide, N-succinimidyl
3-maleimidobenzoate, straight or branched aliphatic (meth)acrylic
acid esters or alicyclic (meth)acrylic acid esters (which may
contain unsaturated bonding partially in a carbon ring),
hydroxyalkyl (meth)acrylates, alkoxyalkyl (meth)acrylates, and
N-substituted maleimides (for example, N-cyclohexylmaleimide).
[0029] The epoxy group-free compound (p2) may further include a
compound which contains two or more ethylene-based unsaturated
groups per molecule. When this compound is used and an amount
thereof is adjusted, hardness and oiliness of the cured product of
the photosensitive resin composition can be easily adjusted. The
compound which contains two or more ethylene-based unsaturated
groups per molecule may include one or more kinds of compounds
selected from a group consisting of, for example, polyethylene
glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate,
trimethylolpropane tri(meth)acrylate, and pentaerythritol
tri(meth)acrylate.
[0030] The ethylene-based unsaturated compound (p) is polymerized
to obtain polymers by a known polymerization method such as, for
example, solution polymerization, and emulsion polymerization.
Examples of the solution polymerization include: a method in which
the ethylene-based unsaturated compound (p) is heated and stirred
in presence of a polymerization initiator in an appropriate organic
solvent under a nitrogen atmosphere; and azeotropic
polymerization.
[0031] The organic solvent used for polymerization of the
ethylene-based unsaturated compound (p) may include one or more
kinds of compounds selected from a group consisting of: for
example, ketones such as methyl ethyl ketone and cyclohexanone;
aromatic hydrocarbons such as toluene and xylene; acetic esters
such as ethyl acetate, butyl acetate, cellosolve acetate, butyl
cellosolve acetate, carbitol acetate, butyl carbitol acetate, and
propylene glycol monomethylether acetate; and dialkyl glycol
ethers.
[0032] The polymerization initiator used for polymerization of the
ethylene-based unsaturated compound (p) may include one or more
kinds of compounds selected from a group consisting of, for
example, hydroperoxides such as diisopropylbenzene hydroperoxide,
dialkyl peroxides such as dicumyl peroxide and
2,5-dimethyl-2,5-di-(t-butylperoxy)-hexane, diacyl peroxides such
as isobutyryl peroxide, ketone peroxides such as methyl ethyl
ketone peroxide, alkyl peresters such as t-butyl peroxypivalate,
peroxydicarbonates such as diisopropyl peroxydicarbonate, azo
compounds such as azobisisobutyronitrile, and redox type
initiators.
[0033] The ethylene-based unsaturated compound (a2) may include a
compound selected from a group consisting of appropriate polymers
and prepolymers. The ethylene-based unsaturated compound (a2) may
include a compound which contains only one ethylene-based
unsaturated group. The compound which contains only one
ethylene-based unsaturated group may include one or more kinds of
compounds selected from a group consisting of, for example, acrylic
acid, methacrylic acid, crotonic acid, cinnamic acid,
2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic
acid, 2-acryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl
phthalic acid, .beta.-carboxyethyl acrylate, 2-acryloyloxypropyl
phthalic acid, 2-methacryloyloxypropyl phthalic acid,
2-acryloyloxyethyl maleic acid, 2-methacryloyloxyethyl maleic acid,
2-acryloyloxyethyl tetrahydrophthalic acid, 2-methacryloyloxyethyl
tetrahydrophthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid,
and 2-methacryloyloxyethyl hexahydrophthalic acid. The
ethylene-based unsaturated compound (a2) may further include a
compound containing a plurality of ethylene-based unsaturated
groups. The compound which contains a plurality of ethylene-based
unsaturated groups may include one or more kinds of compounds
selected from a group consisting of compounds which are obtained by
reacting a dibasic acid anhydride with a polyfunctional acrylate or
a polyfunctional methacrylate which contains a hydroxyl group such
as, for example, pentaerythritol triacrylate, pentaerythritol
trimethacrylate, trimethylolpropane diacrylate, trimethylolpropane
dimethacrylate, dipentaerythritol pentaacrylate, and
dipentaerythritol pentamethacrylate.
[0034] The ethylene-based unsaturated compound (a2) is especially
preferred to include at least one of acrylic acid and methacrylic
acid. In this case, since an ethylene-based unsaturated group,
derived from acrylic acid and methacrylic acid, has especially
excellent photoreactivity, the first resin (a) can gain high
photoreactivity.
[0035] An amount of the ethylene-based unsaturated compound (a2)
used is preferably adjusted so that an amount of carboxyl groups in
the ethylene-based unsaturated compound (a2) is within a range of
0.4 to 1.2 mol per 1 mol of epoxy groups in the epoxy compound
(a1), and especially preferably adjusted so that the amount of
carboxyl groups in the ethylene-based unsaturated compound (a2) is
within a range of 0.5 to 1.1 mol per 1 mol of epoxy groups in the
epoxy compound (a1).
[0036] The compound (a3) selected from polycarboxylic acids and
anhydrides thereof may include one or more kinds of compounds
selected from a group consisting of: for example, dicarboxylic acid
such as phthalic acid, tetrahydrophthalic acid,
methyltetrahydrophthalic acid, methylnadic acid, hexahydrophthalic
acid, methylhexahydrophthalic acid, succinic acid, methylsuccinic
acid, maleic acid, citraconic acid, glutaric acid, and itaconic
acid; polycarboxylic acid of tri or higher basic acid such as
cyclohexane-1,2,4-tricarboxylic acid, trimellitic acid,
pyromellitic acid, benzophenonetetracarboxylic acid, and
methylcyclohexenetetracarboxylic acid; and anhydrides thereof.
[0037] The compound (a3) is used mainly for providing the first
resin (a) with an acid value and thereby supplying the
photosensitive resin composition with redispersibility and
resolubility in a dilute aqueous alkali solution. An amount of the
compound (a3) used is adjusted so that an acid value of the first
resin (a) is preferably greater than or equal to 30 mgKOH/g and
especially preferably greater than or equal to 60 mgKOH/g.
Furthermore, the amount of the compound (a3) used is adjusted so
that an acid value of the first resin (a) is preferably less than
or equal to 160 mgKOH/g and especially preferably less than or
equal to 130 mgKOH/g.
[0038] In synthesis of the first resin (a), a known method can be
employed to promote an addition reaction between the epoxy compound
(a1) and the ethylene-based unsaturated compound (a2) and a
subsequent addition reaction between a product thereof (a product
of the preceding addition reaction) and the compound (a3). For
example, in the addition reaction between the epoxy compound (a1)
and the ethylene-based unsaturated compound (a2), the
ethylene-based unsaturated compound (a2) is added to a solvent
solution of the epoxy compound (a1), then if necessary a heat
polymerization inhibitor and a catalyst are added, and the mixture
is stirred and mixed to obtain a reactive solution. The reactive
solution undergoes the addition reaction using an ordinary method
at a reaction temperature of preferably 60 to 150.degree. C. and
especially preferably 80 to 120.degree. C., and the product of the
preceding addition reaction is obtained. Examples of the heat
polymerization inhibitor include hydroquinone and hydroquinone
monomethyl ether. Examples of the catalyst include tertiary amines
such as benzyldimethylamine and triethylamine, quaternary ammonium
salts such as trimethylbenzylammonium chloride and
methyltriethylammonium chloride, triphenylphosphine, and
triphenylstibine.
[0039] In order to promote the subsequent addition reaction between
the product of the preceding addition reaction and the compound
(a3), the compound (a3) is added to a solvent solution of the
product of the preceding addition reaction, then if necessary a
heat polymerization inhibitor and a catalyst are added, and the
mixture is stirred and mixed to obtain a reactive solution. The
reactive solution undergoes the addition reaction using an ordinary
method, and the first resin (a) is obtained. Reaction conditions
may be same as reaction conditions of the preceding addition
reaction between the epoxy compound (a1) and the ethylene-based
unsaturated compound (a2).
[0040] The heat polymerization inhibitor and the catalyst used for
the preceding addition reaction between the epoxy compound (a1) and
the ethylene-based unsaturated compound (a2), which contains a
carboxyl group, may be used.
[0041] The component (F1) may include carboxyl group-containing
(meth)acrylic copolymer resin (referred to as second resin (b))
obtained from a reaction between a part of carboxyl groups in a
polymer of an ethylene-based unsaturated monomer including an
ethylene-based unsaturated compound which contains a carboxyl
group, and an ethylene-based unsaturated compound which contains an
epoxy group. The ethylene-based unsaturated monomer may include an
ethylene-based unsaturated compound which does not contain any
carboxyl groups, if necessary.
[0042] The second resin (b) may include aromatic ring-containing
(meth)acrylic copolymer resin. That is, the component (A) may
include the aromatic ring-containing (meth)acrylic copolymer resin.
In this case, heat resistance of the cured product of the
photosensitive resin composition is especially increased. Note that
the aromatic ring-containing (meth)acrylic copolymer resin is
(meth)acrylic copolymer resin which contains aromatic rings. When
the ethylene-based unsaturated monomer includes a compound which
contains aromatic rings, the aromatic ring-containing (meth)acrylic
copolymer resin is obtained.
[0043] The ethylene-based unsaturated compound, which contains a
carboxyl group, used to obtain the second resin (b) may include
appropriate polymers and prepolymers. For example, the
ethylene-based unsaturated compound, which contains a carboxyl
group, may include a compound which contains only one
ethylene-based unsaturated group. Specifically, the ethylene-based
unsaturated compound, which contains a carboxyl group, may include
one or more kinds of compounds selected from a group consisting of,
for example, acrylic acid, methacrylic acid,
.omega.-carboxyl-polycaprolactone (n.apprxeq.2) monoacrylate,
crotonic acid, cinnamic acid, 2-acryloyloxyethyl succinic acid,
2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic
acid, 2-methacryloyloxyethyl phthalic acid,
.beta.-carboxyethylacrylate, 2-acryloyloxypropyl phthalic acid,
2-methacryloyloxypropyl phthalic acid, 2-acryloyloxyethyl maleic
acid, 2-methacryloyloxyethyl maleic acid, 2-acryloyloxyethyl
tetrahydrophthalic acid, 2-methacryloyloxyethyl tetrahydrophthalic
acid, 2-acryloyloxyethyl hexahydrophthalic acid, and
2-methacryloyloxyethyl hexahydrophthalic acid. The ethylene-based
unsaturated compound, which contains a carboxyl group, may also
include a compound which contains a plurality of ethylene-based
unsaturated groups.
[0044] Specifically, the ethylene-based unsaturated compound, which
contains a carboxyl group, may include a compound obtained by
reacting a dibasic acid anhydride with a polyfunctional
(meth)acrylate, which contains a hydroxyl group, selected from a
group consisting of, for example, pentaerythritol triacrylate,
pentaerythritol trimethacrylate, trimethylolpropane diacrylate,
trimethylolpropane dimethacrylate, dipentaerythritol pentaacrylate,
and dipentaerythritol pentamethacrylate. These compounds may be
used alone or in combination.
[0045] The ethylene-based unsaturated compound, which does not
contain any carboxyl groups, used to obtain the second resin (b)
may be any compound as long as it is copolymerizable with the
ethylene-based unsaturated compound which contains a carboxyl
group. The ethylene-based unsaturated compound, which does not
contain any carboxyl groups, may include either one of an aromatic
ring-containing compound and an aromatic ring-free compound. When
the ethylene-based unsaturated compound, which does not contain any
carboxyl groups, includes the aromatic ring-containing compound, an
aromatic ring-containing (meth)acrylic copolymer resin is
obtained.
[0046] The aromatic ring-containing compound may include one of
more kinds of compounds selected from a group consisting of, for
example, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, benzyl
(meth)acrylate, neopentyl glycol benzoate (meth)acrylate, paracumyl
phenoxyethylene glycol (meth)acrylate, EO-modified cresol
(meth)acrylate, ethoxylated phenyl (meth)acrylate, nonylphenoxy
polyethylene glycol (meth)acrylate (n=2-17), ECH-modified phenoxy
(meth)acrylate, phenoxy diethylene glycol (meth)acrylate,
phenoxyethyl (meth)acrylate, phenoxy hexaethylene glycol
(meth)acrylate, phenoxy tetraethylene glycol (meth)acrylate,
tribromophenyl (meth)acrylate, EO-modified tribromophenyl (meth)
acrylate, EO-modified bisphenol A di(meth)acrylate, PO-modified
bisphenol A di(meth)acrylate, modified bisphenol A
di(meth)acrylate, EO-modified bisphenol F di(meth)acrylate,
ECH-modified phthalic acid di(meth)acrylate, trimethylolpropane
benzoate (meth)acrylate, EO-modified phthalic acid (meth)acrylate,
EO/PO-modified phthalic acid (meth)acrylate, N-phenylmaleimide,
N-benzylmaleimide, N-vinylcarbazole, styrene, vinylnaphthalene, and
4-vinylbiphenyl.
[0047] The aromatic ring-free compound may include one or more
kinds of compounds selected from a group consisting of, for
example, straight or branched aliphatic (meth)acrylic acid esters
or alicyclic (meth)acrylic acid esters (which may contain
unsaturated bonding partially in a carbon ring), hydroxyalkyl
(meth)acrylates, alkoxyalkyl (meth)acrylates, and N-substituted
maleimides such as N-cyclohexylmaleimide. The aromatic ring-free
compound may further include a compound, which contains two or more
ethylene-based unsaturated groups per molecule, such as
polyethylene glycol di(meth)acrylate, polypropylene glycol
di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and
pentaerythritol tri(meth)acrylate. These compounds may be used
alone or in combination. These compounds are preferred since
hardness and oiliness of the cured product of the photosensitive
resin composition can be easily adjusted.
[0048] Examples of the ethylene-based unsaturated compound, which
contains an epoxy group, used to obtain the second resin (b)
include appropriate polymers and prepolymers. Specific examples of
the ethylene-based unsaturated compound, which contains an epoxy
group, may include epoxycyclohexyl derivatives of acrylic acid or
methacrylic acid, an alicyclic epoxy derivative of acrylates or
methacrylates, .beta.-methylglycidyl acrylate, and
.beta.-methylglycidyl methacrylate. These compounds may be used
alone or in combination. Especially, it is preferred to use
glycidyl (meth)acrylate, which is widely used and easily
obtained.
[0049] The component (F1) may include resin (hereinafter referred
to as third resin (C)) obtained by adding a compound, which
contains an ethylene-based unsaturated group and an isocyanate
group, to a part or all of hydroxyl groups in a polymer of an
ethylene-based unsaturated monomer including an ethylene-based
unsaturated compound, which contains a carboxyl group, and an
ethylene-based unsaturated compound, which contains an epoxy group.
The ethylene-based unsaturated monomer may include an
ethylene-based unsaturated compound which does not contain any
carboxyl groups or hydroxyl groups, if necessary.
[0050] The ethylene-based unsaturated compound, which contains a
carboxyl group, used to obtain the third resin (c) may be selected
from, for example, compounds which can be used as the
ethylene-based unsaturated compound, which contains a carboxyl
group, used to obtain the second resin (b).
[0051] Examples of the ethylene-based unsaturated compound, which
contains a hydroxyl group, used to obtain the third resin (c)
include: hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl
(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl
(meth) acrylate, cyclohexane dimethanol mono(meth)acrylate,
2-(meth)acryloyloxyethyl-2-hydroxyethylphthalate, caprolactone
(meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene
glycol (meth)acrylate, trimethylolpropane di(meth)acrylate,
pentaerythritol tri(meth)acrylate, and dipentaerythritol
penta(meth)acrylate; hydroxybutyl vinyl ether; hydroxyethyl vinyl
ether; and N-hydroxyethyl (meth)acrylamide.
[0052] Examples of the compound, which contains an ethylene-based
unsaturated group and an isocyanate group, used to obtain the third
resin (c) include 2-acryloyloxyethyl isocyanate (for example,
KarenzAOI manufactured by Showa Denko K.K.), 2-methacryloyloxyethyl
isocyanate (for example, KarenzMOI manufactured by Showa Denko
K.K.), methacryloyloxy ethoxyethyl isocyanate (for example,
KarenzMOI-EG manufactured by Showa Denko K.K.), isocyanate blocked
compound of KarenzMOI (for example, KarenzMOI-BM manufactured by
Showa Denko K.K.), isocyanate blocked compound of KarenzMOI (for
example, KarenzMOI-BP manufactured by Showa Denko K.K.), and
1,1-(bisacryloyloxymethyl)ethyl isocyanate (for example, KarenzBEI
manufactured by Showa Denko K.K.).
[0053] A weight-average molecular weight of the entire component
(F1) is preferably within a range of 800 to 100000. Within this
range, the photosensitive resin composition gains especially
excellent photosensitivity and resolution.
[0054] An acid value of the entire component (F1) is preferably
greater than or equal to 30 mgKOH/g. In this case, the
photosensitive resin composition gains good developability. The
acid value is further preferably greater than or equal to 60
mgKOH/g. In addition, the acid value of the entire component (F1)
is preferably smaller than or equal to 180 mgKOH/g. In this case,
an amount of remaining carboxyl groups in the cured product of the
photosensitive resin composition decreases, thus maintaining good
electric properties, electric corrosion resistance and water
resistance of the cured product. The acid value is further
preferably smaller than or equal to 150 mgKOH/g.
[0055] The photosensitive resin composition may further include a
compound (hereinafter referred to as a component (F2)) which
contains a carboxyl group but is not photopolymerizable. The
component (F2) can provide the photosensitive resin composition
with alkali developability.
[0056] The component (F2) includes, for example, a polymer of an
ethylene-based unsaturated monomer including an ethylene-based
unsaturated compound which contains a carboxyl group. The
ethylene-based unsaturated monomer may include an ethylene-based
unsaturated compound which does not contain any carboxyl
groups.
[0057] The ethylene-based unsaturated compound, which contains a
carboxyl group, may include appropriate polymers and prepolymers,
and may include, for example, a compound which contains only one
ethylene-based unsaturated group. Specifically, the ethylene-based
unsaturated compound, which contains a carboxyl group, may include
one or more kinds of compounds selected from a group consisting of,
for example, acrylic acid, methacrylic acid,
.omega.-carboxyl-polycaprolactone (n.apprxeq.2) monoacrylate,
crotonic acid, cinnamic acid, 2-acryloyloxyethyl succinic acid,
2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic
acid, 2-methacryloyloxyethyl phthalic acid, 2-acryloyloxypropyl
phthalic acid, 2-methacryloyloxypropyl phthalic acid,
2-acryloyloxyethyl maleic acid, 2-methacryloyloxyethyl maleic acid,
.beta.-carboxyethylacrylate, 2-acryloyloxyethyl tetrahydrophthalic
acid, 2-methacryloyloxyethyl tetrahydrophthalic acid,
2-acryloyloxyethyl hexahydrophthalic acid, and
2-methacryloyloxyethyl hexahydrophthalic acid. The ethylene-based
unsaturated compound, which contains a carboxyl group, may also
include a compound which contains a plurality of ethylene-based
unsaturated groups. Specifically, the ethylene-based unsaturated
compound, which contains a carboxyl group, may include a compound
obtained by reacting a dibasic acid anhydride with a polyfunctional
(meth)acrylate, which contains a hydroxyl group, selected from a
group consisting of, for example, pentaerythritol triacrylate,
pentaerythritol trimethacrylate, trimethylolpropane diacrylate,
trimethylolpropane dimethacrylate, dipentaerythritol pentaacrylate,
and dipentaerythritol pentamethacrylate. These compounds may be
used alone or in combination.
[0058] The ethylene-based unsaturated compound, which does not
contain any carboxyl groups, may be any compound as long as it is
copolymerizable with the ethylene-based unsaturated compound which
contains a carboxyl group. The ethylene-based unsaturated compound,
which does not contain any carboxyl groups, may include either one
of an aromatic ring-containing compound and an aromatic ring-free
compound.
[0059] The aromatic ring-containing compound may include one or
more kinds of compounds selected from a group consisting of, for
example, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, benzyl
(meth)acrylate, neopentyl glycol benzoate (meth)acrylate, paracumyl
phenoxyethylene glycol (meth)acrylate, EO-modified cresol
(meth)acrylate, ethoxylated phenyl (meth)acrylate, nonylphenoxy
polyethylene glycol (meth)acrylate (n=2-17), ECH-modified phenoxy
(meth)acrylate, phenoxy diethylene glycol (meth)acrylate,
phenoxyethyl (meth)acrylate, phenoxy hexaethylene glycol
(meth)acrylate, phenoxy tetraethylene glycol (meth)acrylate,
tribromophenyl (meth)acrylate, EO-modified tribromophenyl (meth)
acrylate, EO-modified bisphenol A di(meth)acrylate, PO-modified
bisphenol A di(meth)acrylate, modified bisphenol A
di(meth)acrylate, EO-modified bisphenol F di(meth)acrylate,
ECH-modified phthalic acid di(meth)acrylate, trimethylolpropane
benzoate (meth)acrylate, EO-modified phthalic acid (meth)acrylate,
EO/PO-modified phthalic acid (meth)acrylate, N-phenylmaleimide,
N-benzylmaleimide, N-vinylcarbazole, styrene, vinylnaphthalene, and
4-vinylbiphenyl.
[0060] The aromatic ring-free compound may include one or more
kinds of compounds selected from a group consisting of, for
example, straight or branched aliphatic (meth)acrylic acid esters
or alicyclic (meth)acrylic acid esters (which may contain
unsaturated bonding partially in a carbon ring), hydroxyalkyl
(meth)acrylates, alkoxyalkyl (meth)acrylates, and N-substituted
maleimides such as N-cyclohexylmaleimide. The aromatic ring-free
compound may further include a compound, which contains two or more
ethylene-based unsaturated groups per molecule, such as
polyethylene glycol di(meth)acrylate, polypropylene glycol
di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and
pentaerythritol tri(meth)acrylate. These compounds may be used
alone or in combination. These compounds are preferred since
hardness and oiliness of the cured product of the photosensitive
resin composition can be easily adjusted.
[0061] Kinds and ratios of compounds used to obtain the component
(F2) appropriately selected so that an acid value of the component
(F2) is an appropriate value. The acid value of the component (F2)
is preferably within a range of 20 to 180 mgKOH/g and further
preferably within a range of 35 to 165 mgKOH/g.
[0062] The component (B) (the titanium dioxide) colors the cured
product of the photosensitive resin composition white, and
accordingly the cured product can gain high light reflectivity. The
component (B) may contain, for example, either one or both of
rutile titanium dioxide and anatase titanium dioxide. Especially,
the titanium dioxide is preferably includes the rutile titanium
dioxide which has low catalyst activity and high thermal stability.
The rutile titanium dioxide is manufactured industrially with a
chlorine method or a sulfuric acid method. In the present
embodiment, the rutile titanium dioxide may include either one or
both of rutile titanium dioxide manufactured with a chlorine method
and rutile titanium dioxide manufactured with a sulfuric acid
method.
[0063] In the present embodiment, as described above, the component
(C) (the photopolymerization initiator) includes the component (C1)
(the acylphosphine oxide-containing photopolymerization initiator)
and the component (C2) (the phenylglyoxylate-containing
photopolymerization initiator.).
[0064] The component (C1) may include either one or both of a
monoacylphosphine oxide-containing photopolymerization initiator
and a bisacylphosphine oxide-containing photopolymerization
initiator.
[0065] The monoacylphosphine oxide-containing photopolymerization
initiator may include, for example, at least one of
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and
2,4,6-trimethylbenzoyl-ethyl-phenyl-phosphinate.
[0066] The bisacylphosphine oxide-containing photopolymerization
initiator may include one or more kinds of constituents selected
from a group consisting of bis-(2,6-dichlorobenzoyl)phenylphosphine
oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide,
bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide,
bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide,
bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide,
bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide,
bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide,
bis-(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and
(2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide.
Especially, the component (C1) preferably includes at least one of
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and
bis-(2,4,6-trimethylbenzoyl)phenylphosphine oxide. It is also
preferable that the component (C1) includes
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and/or
bis-(2,4,6-trimethylbenzoyl)phenylphosphine oxide only. In these
cases, coloring of the cured product of the photosensitive resin
composition is further prevented.
[0067] The component (C2) may include at least one of
(1,2-dioxo-2-methoxyethyl)benzene and a mixture of oxyphenylacetic
acid 2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic
acid 2-(2-hydroxyethoxy)ethyl ester. In other words, the component
(C2) may include only (1,2-dioxo-2-methoxyethyl)benzene, only a
mixture of oxyphenylacetic acid
2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic acid
2-(2-hydroxyethoxy)ethyl ester, or both of
(1,2-dioxo-2-methoxyethyl)benzene and a mixture of oxyphenylacetic
acid 2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic
acid 2-(2-hydroxyethoxy)ethyl ester.
[0068] In the present embodiment, no matter which of the
monoacylphosphine oxide-containing photopolymerization initiator or
the bisacylphosphine oxide-containing photopolymerization initiator
is included in the component (C1), the photosensitive resin
composition can be thoroughly cured from its surface to its deep
part when the photosensitive resin composition formed into a film
is irradiated with light. The reason for this is considered as
follows.
[0069] The monoacylphosphine oxide-containing photopolymerization
initiator has high solubility in the photosensitive resin
composition but has relatively low reactivity. Accordingly, when
the monoacylphosphine oxide-containing photopolymerization
initiator is used alone as the photopolymerization initiator, using
a high concentration of the monoacylphosphine oxide-containing
photopolymerization initiator to gain good photocurability may lead
to light absorption caused by a high concentration of the
monoacylphosphine oxide-containing photopolymerization initiator
existing in a surface part of the photosensitive resin composition,
resulting in decrease in an amount of light reaching to a deep part
of the photosensitive resin composition. Consequently, curability
in the deep part is lowered.
[0070] On the other hand, the bisacylphosphine oxide-containing
photopolymerization initiator has relatively good reactivity but
has low solubility in the photosensitive resin composition.
Accordingly, using a high concentration of the bisacylphosphine
oxide-containing photopolymerization initiator in the
photosensitive resin condition may lead to lack of surface
uniformity of a coating film. When a low concentration of the
bisacylphosphine oxide-containing photopolymerization initiator is
used alone as the photopolymerization initiator to maintain surface
uniformity of the coating film, it becomes difficult to cure the
photosensitive resin composition uniformly.
[0071] However, photocurability of the photosensitive resin
composition can be improved since the component (C2) can absorb
light having a wavelength of about 380 to 420 nm. In addition,
photocurability of the surface part of the photosensitive resin
composition can be improved since the component (C2) has especially
high absorptivity of light having a wavelength of around 280 nm.
Furthermore, since the component (C2) can dissolve the component
(C1) well, the component (C) has good dispersibility in the
photosensitive resin composition.
[0072] Therefore, the photosensitive resin composition can be
thoroughly cured from its surface to its deep part when the
photosensitive resin composition is irradiated with light.
[0073] The component (C) may include the monoacylphosphine
oxide-containing photopolymerization initiator and the component
(C2). The component (C) may include only the monoacylphosphine
oxide-containing photopolymerization initiator and the component
(C2).
[0074] The component (C) may include the bisacylphosphine
oxide-containing photopolymerization initiator and the component
(C2). The component (C) may include only the bisacylphosphine
oxide-containing photopolymerization initiator and the component
(C2). In this case, compared to a case where the component (C1)
includes only the monoacylphosphine oxide-containing
photopolymerization initiator, even a low concentration of the
bisacylphosphine oxide-containing photopolymerization initiator can
lead to curability in the deep part of the photosensitive resin
composition.
[0075] The component (C) preferably includes only the component
(C1) and the component (C2). However, the component (C) may include
a compound other than the component (C1) or the component (C2),
without departing from the scope of the present invention. The
compound other than the component (C1) or the component (C2) may
include one or more kinds of compounds selected from a group
consisting of: for example, benzoin and alkylethers thereof,
acetophenones such as acetophenone and benzyldimethyl ketal;
anthraquinones such as 2-methylanthraquinone; thioxanthones such as
2,4-dimethylthioxanthone, 2,4-diethylthioxanthone,
2-isopropylthioxanthone, 4-isopropylthioxanthone, and
2,4-diisopropylthioxanthone; benzophenones such as benzophenone and
4-benzoyl-4'-methyldiphenylsulfide; xanthones such as
2,4-diisopropylxanthone; nitrogen atom-containing compounds such as
2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propane;
1,2-octanedione; 1-[4-(phenylthio)-2-(O-benzoyloxyme)] (IRGACURE
OXE 01); ethanone; and
1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime)
(IRGACURE OXE 02).
[0076] In the entire component (C), the component (C1) and the
component (C2) are preferably included within a range of 3 to 100
weight % in total. In this case, the photosensitive resin
composition has especially high photocurability. The component (C1)
and the component (C2) are more preferably included within a range
of 6 to 100 weight % in total, further preferably within a range of
9 to 100 weight %, and especially preferably within a range of 50
to 100 weight %.
[0077] In addition, in the entire component (C1) and component
(C2), the component (C1) is preferably included within a range of 1
to 99 weight %. In this case, the cured product of the
photosensitive resin composition can be thoroughly and highly
uniformly cured from its surface to its deep part. The component
(C1) is more preferably included within a range of 5 to 60 weight %
and further preferably within a range of 10 to 40 weight %
[0078] The photosensitive resin composition may further include a
known photopolymerization promotor and a known sensitizer. The
photosensitive resin composition may include, for example,
p-dimethylbenzoic acid ethylether, p-dimethylaminobenzoic acid
isoamyl ester, and 2-dimethylamylethyl benzoate.
[0079] The photosensitive resin composition may include (D) an
epoxy compound. In this case, the photosensitive resin composition
can gain thermosettability. When the photosensitive resin
composition includes the component (D), in order for the
photosensitive resin composition to gain enough thermosettability,
the photosensitive resin composition preferably includes a compound
which contains a carboxyl group. That is the photosensitive resin
composition preferably includes at least one of the component (F1)
and the component (F2).
[0080] The component (D) preferably contains at least two epoxy
groups per molecule. The component (D) may include either one of a
hardly soluble epoxy compound and a generic soluble epoxy
compound.
[0081] The component (D) may include one or more kinds of
components selected from a group consisting of, for example, phenol
novolak epoxy resin (for example, EPICLON N-775 manufactured by DIC
Corporation), cresol novolak epoxy resin (for example, EPICLON
N-695 manufactured by DIC Corporation), bisphenol A epoxy resin
(for example, jER1001 manufactured by Mitsubishi Chemical
Corporation), bisphenol A-novolak epoxy resin (for example, EPICLON
N-865 manufactured by DIC Corporation), bisphenol F epoxy resin
(for example, jER4004P manufactured by Mitsubishi Chemical
Corporation), bisphenol S epoxy resin (for example, EPICLON
EXA-1514 manufactured by DIC Corporation), bisphenol AD epoxy
resin, biphenyl epoxy resin (for example, YX4000 manufactured by
Mitsubishi Chemical Corporation), biphenyl novolak epoxy resin (for
example, NC-3000 manufactured by Nippon Kayaku Co., Ltd.),
hydrogenated bisphenol A epoxy resin (for example, ST-4000D
manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.),
naphthalene epoxy resin (for example, EPICLON HP-4032, EPICLON
HP-4700, EPICLON HP-4770 manufactured by DIC Corporation),
hydroquinone epoxy resin (for example, YDC-1312 manufactured by
Nippon Steel & Sumikin Chemical Co., Ltd.), tertiary
butylcatechol epoxy resin (for example, EPICLON HP-820 manufactured
by DIC Corporation), dicyclopentadiene epoxy resin (for example,
EPICLON HP-7200 manufactured by DIC Corporation), adamantane epoxy
resin (for example, ADAMANTATE X-E-201 manufactured by Idemitsu
Kosan Co., Ltd.), biphenylether epoxy resin (for example, YSLV-80DE
manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.),
special two-functional epoxy resin (for example, YL7175-500 and
YL7175-1000 manufactured by Mitsubishi Chemical Corporation;
EPICLON TSR-960, EPICLON TER-601, EPICLON TSR-250-80BX, EPICLON
1650-75MPX, EPICLON EXA-4850, EPICLON EXA-4816, EPICLON EXA-4822,
and EPICLON EXA-9726 manufactured by DIC Corporation; YSLV-120TE
manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and
bisphenol epoxy resins excluding the above.
[0082] The component (D) also preferably includes
phosphorus-containing epoxy resin. In this case, flame retardancy
of the cured product of the photosensitive resin composition is
improved. Examples of the phosphorus-containing epoxy resin include
phosphoric acid-modified bisphenol F epoxy resin (for example,
EPICLON EXA-9726 and EPICLON EXA-97106 manufactured by DIC
Corporation) and EPIKOTE FX-305 manufactured by Nippon Steel &
Sumikin Chemical Co., Ltd.
[0083] The component (D) preferably includes a crystalline epoxy
compound which has a melting point within a range of 130 to
160.degree. C. In this case, tackiness of a dry coating film formed
with the photosensitive resin composition is suppressed. Also in
this case, when the photosensitive resin composition is dried by
heating at a relatively low temperature around 60 to 80.degree. C.,
even if the photosensitive resin composition includes the compound
which contains a carboxyl group, the compound, which contains a
carboxyl group, and the component (D) (the epoxy compound) are not
easily reacted. Accordingly, the compound, which contains a
carboxyl group, tends to remain unreacted in the dry coating film.
Therefore, the dry coating film is first exposed to light and then
developed so that high alkali developability can be assured in
formation of a film. Furthermore, when the film after development
is heated at an appropriate temperature, for example at 150.degree.
C., the component (D) (the epoxy compound) in the film easily
softens or melts, leading to a thermosetting reaction in the film
involving the component (D) (the epoxy compound). Consequently, the
cured product gains high heat resistance and high hardness. The
crystalline epoxy compound may include one or more kinds of
compounds selected from a group consisting of, for example,
triglycidyl isocyanurate, a hydroquinone epoxy compound represented
by following formula (1) (such as YDC-1312 manufactured by Nippon
Steel & Sumikin Chemical Co., Ltd.), and tetrakisphenol ethane
crystalline epoxy resin (such as GTR-1800 manufactured by Nippon
Kayaku Co., Ltd.). In the entire component (D), the crystalline
epoxy compound, which has a melting point within a range of 130 to
160.degree. C., is preferably included within 3 to 100 weight
%.
##STR00001##
[0084] R.sup.1, R.sup.2, R.sup.3, and R.sup.4 in the formula (1)
are independently a methyl group, a hydrogen atom, or a t-butyl
group
[0085] When the component (D) includes the triglycidyl
isocyanurate, the triglycidyl isocyanurate is especially preferably
in a form of .beta. isomers, in which three epoxy groups are
located on the same side with respect to a flat s-triazine ring, or
in a mixture of .beta. isomers and .alpha. isomers, in which one
epoxy group is located on the different side from other two epoxy
groups with respect to a flat s-triazine ring. When the component
(D) includes the triglycidyl isocyanurate, crosslinking density in
the cured product of the photosensitive resin composition is
increased, leading to high hardness of the cured product. In
addition, heat resistance and heat discoloration resistance of the
cured product are also increased. When the component (D) includes
the triglycidyl isocyanurate, the triglycidyl isocyanurate is
preferably included within 3 to 100 weight % in the entire
component (D).
[0086] When the component (D) includes the hydroquinone epoxy
compound represented by formula (1), since the hydroquinone epoxy
compound has only one aromatic ring, a long conjugated bond is less
likely to occur even if the cured product of the photosensitive
resin composition is decomposed due to heat or light. Furthermore,
the hydroquinone epoxy compound does not contain nitrogen atom or
sulfur atom. As a result, the cured product tends not to discolor.
In addition, since the hydroquinone epoxy compound is bifunctional
and contains an ether bond, the cured product has a reduced
brittleness and thus cracks are not likely to occur when the cured
product undergoes machining methods.
[0087] When the component (D) includes the hydroquinone epoxy
compound, the hydroquinone epoxy compound is preferably included
within 3 to 100 weight % in the entire component (D).
[0088] The photosensitive resin composition may include (E) an
antioxidant. When the photosensitive resin composition includes the
component (E), heat discoloration resistance of the cured product
of the photosensitive resin composition is increased.
[0089] A melting point of the component (E) is preferably within a
range of 50 to 150.degree. C. With the melting point higher than or
equal to 50.degree. C., bleedout of the component (E) from the
photosensitive resin composition or the film can be prevented, when
the photosensitive composition is dried by heating or the film
formed with the photosensitive resin composition is cured by
heating. Also, with the melting point lower than or equal to
150.degree. C., crystals of the component (E) is prevented from
rising to a surface of the coating film formed with the
photosensitive resin composition, resulting in prevention of
lowered uniformity on a surface of the cured product.
[0090] The component (E) may include at least one kind of compound
selected from a group consisting of, for example, hindered phenolic
antioxidants such as IRGANOX 245 (melting point of 76 to 79.degree.
C.), IRGANOX 259 (melting point of 104 to 108.degree. C.), IRGANOX
1035 (melting point of 63 to 67.degree. C.), IRGANOX 1098 (melting
point of 156 to 161.degree. C.), IRGANOX 1010 (melting point of 110
to 125.degree. C.), IRGANOX 1076 (melting point of 50 to 55.degree.
C.), and IRGANOX 1330 (melting point of 240 to 245.degree. C.)
manufactured by BASF Corporation, ADEKA STAB AO-20 (melting point
of 220 to 222.degree. C.), ADEKA STAB AO-30 (melting point of 183
to 185.degree. C.), ADEKA STAB AO-40 (melting point of 210 to
214.degree. C.), ADEKA STAB AO-50 (melting point of 51 to
54.degree. C.), ADEKA STAB AO-60 (110 to 130.degree. C.), ADEKA
STAB AO-80 (110 to 120.degree. C.), and ADEKA STAB AO-330 (melting
point of 243 to 245.degree. C.) manufactured by ADEKA CORPORATION,
SEENOX224M (melting point of 129 to 132.degree. C.) and SEENOX326M
(melting point of 241 to 249.degree. C.) manufactured by SHIPRO
KASEI KAISHA, Ltd., SUMILIZER GA-80 (melting point of higher than
or equal to 110.degree. C.) and SUMILIZER MDP-S (melting point of
higher than or equal to 128.degree. C.) manufactured by Sumitomo
Chemical CO., Ltd., and Antage BHT (melting point of higher than or
equal to 69.degree. C.), Antage W-300 (melting point of higher than
or equal to 205.degree. C.), Antage W-400 (melting point of higher
than or equal to 120.degree. C.), and Antage W-500 (melting point
of higher than or equal to 120.degree. C.) manufactured by
Kawaguchi Chemical Industry Co., LTD. Especially, the component (E)
preferably includes IRGANOX 1010 (melting point of 110 to
125.degree. C.).
[0091] The photosensitive resin composition may include an organic
solvent. The organic solvent is used to liquefy the photosensitive
resin composition or form varnish with the photosensitive resin
composition, and to adjust viscosity, applicability, and
film-formability.
[0092] The organic solvent may include one or more kinds of
compounds selected from a group consisting of, for example,
straight, branched, secondary, or poly alcohols such as ethanol,
propyl alcohol, isopropyl alcohol, hexanol, and ethylene glycol;
ketones such as methyl ethyl ketone and cyclohexanone; aromatic
hydrocarbons such as toluene and xylene; petroleum aromatic mixed
solvents such as Swazol series (manufactured by Maruzen
Petrochemical Co., Ltd.) and Solvesso series (manufactured by Exxon
Mobil Chemical Corporation); cellosolves such as cellosolve and
butyl cellosolve; carbitols such as carbitol and butyl carbitol;
propylene glycol alkyl ethers such as propylene glycol methyl
ether; polypropylene glycol alkyl ethers such as dipropylene glycol
methyl ether; acetic acid esters such as ethyl acetate, butyl
acetate, cellosolve acetate, and carbitol acetate; and dialkyl
glycol ethers.
[0093] An amount of the organic solvent in the photosensitive resin
composition is preferably adjusted so that the organic solvent
volatilizes quickly when a coating film formed with the
photosensitive resin composition is dried, i.e. the organic solvent
does not remain in the dried coating film. The amount of the
organic solvent in the entire photosensitive resin composition is
preferably within a range of 0 to 99.5 weight %, and further
preferably within a range of 15 to 60 weight %. Note that, since an
appropriate amount of the organic solvent depends on a coating
method, the amount is preferably adjusted appropriately depending
on the coating method.
[0094] Within the scope of the present invention, the
photosensitive resin composition may include components other than
the above.
[0095] For example, the photosensitive resin composition may
include one or more kinds of resin selected from a group consisting
of blocked isocyanates of tolylene diisocyanate, morpholine
diisocyanate, isophorone diisocyanate, and hexamethylene
diisocyanate which are blocked with caprolactam, oxime, maloic acid
ester, and the like; amino resin such as melamine resin,
n-butylated melamine resin, isobutylated melamine resin, butylated
urea resin, butylated melamine-urea cocondensed resin, and
benzoguanamine-based cocondensed resin; various thermosetting resin
other than the above; photocuring epoxy (meth)acrylate; resin
obtained by adding (meth)acrylic acid to epoxy resin such as
bisphenol A type epoxy resin, phenol novolak type epoxy resin,
cresol novolak type expoxy resin, and alicyclic expoxy resin; and
polymeric compounds such as diallyl phthalate resin, phenoxy resin,
urethane resin, and fluorine resin.
[0096] When the photosensitive resin composition includes the epoxy
compound (the component (D)), the photosensitive resin composition
may further include a curing agent to cure the epoxy compound. The
curing agent may include, for example, one or more kinds of
compounds selected from a group consisting of imidazole derivatives
such as imidazole, 2-methylimidazole, 2-ethylimidazole,
2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenyl imidazole,
1-cyanoethyl-2-phenylimidazole, and
1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as
dicyandiamide, benzyldimethylamine,
4-(dimethylamino)-N,N-dimethylbenzylamine,
4-methoxy-N,N-dimethylbenzylamine, and
4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as
adipic acid hydrazide and sebacic acid hydrazide; phosphorus
compounds such as triphenylphosphine; acid anhydrides; phenols;
mercaptans; Lewis acid amine complexes; and onium salts. Examples
of commercial products of the above compounds may include 2MZ-A,
2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ manufacture by Shikoku Chemicals
Corporation, (which are names for commercial products of imidazole
compounds), U-CAT3503N and U-CAT3502T manufactured by San-Apro
Ltd., (which are names for commercial products of blocked
isocyanates of dimethylamine,) and DBU, DBN, U-CATSA102, and
U-CAT5002 manufactured by San-Apro Ltd., (which are bicyclic
diamine compounds and salts thereof).
[0097] The photosensitive resin composition may include an adhesion
imparting agent. Examples of the adhesion imparting agent may
include guanamine, acetoguanamine, benzoguanamine, melamine, and
S-triazine derivatives such as
2,4-diamino-6-methacryloyloxyethyl-S-triazine,
2-vinyl-4,6-diamino-S-triazine,
2-vinyl-4,6-diamino-S-triazine-isocyanuric acid adduct, and
2,4-diamino-6-methacryloyloxyethyl-S-triazine-isocyanuric acid
adduct.
[0098] The photosensitive resin composition may include one or more
kinds of constituents selected from a group consisting of a curing
promotor; a coloring agent other than white; a copolymer such as
silicones and acrylates; a leveling agent; an adhesion imparting
agent such as silane coupling agents; a thixotropy agent; a
polymerization inhibitor; a halation preventer; a flame retardant;
a defoaming agent; a surfactant; a polymer dispersant; and an
inorganic filler such as barium sulfate, crystalline silica, nano
silica, carbon nanotube, talc, bentonite, aluminum hydroxide, and
magnesium hydroxide.
[0099] An amount of each component in the photosensitive resin
composition is appropriately adjusted so that the photosensitive
resin composition has photocurability and is developable with an
alkaline aqueous solution.
[0100] In the photosensitive resin composition, the amount of the
component (A) is preferably within a range of 5 to 95 weight %,
more preferably within a range of 10 to 90 weight %, and further
preferably within a range of 10 to 40 weight %, with respect to
solid content of the photosensitive resin composition.
[0101] In the photosensitive resin composition, the amount of the
component (B) is preferably within a range of 15 to 500 parts by
mass, with respect to 100 parts by mass of the component (A).
Furthermore, in the photosensitive resin composition, the amount of
the component (B) is preferably within a range of 3 to 220 weight %
and further preferable within a range of 10 to 180 weight %, with
respect to resin content of the photosensitive resin
composition.
[0102] In the photosensitive resin composition, the amount of the
component (C) is preferably within a range of 0.1 to 30 weight %
and further preferably within a range of 1 to 28 weight %, with
respect to solid content of the photosensitive resin
composition.
[0103] When the photosensitive resin composition includes the
component (D), in the photosensitive resin composition, the amount
of the component (D) is preferably within a range of 1.5 to 85
weight %, more preferably within a range of 1.5 to 60 weight %, and
further preferably within a range of 2 to 40 weight %, with respect
to solid content of the photosensitive resin composition.
[0104] In the photosensitive resin composition, the amount of the
component (E) is preferably within a range of 0.005 to 15 weight %
and further preferably within a range of 0.05 to 10 weight %, with
respect to solid content of the photosensitive resin
composition.
[0105] When the photosensitive resin composition includes at least
one of the component (F1) and the component (F2), in the
photosensitive resin composition, the total amount of the component
(F1) and the component (F2) is preferably within a range of 5 to 85
weight %, more preferably within a range of 10 to 75 weight %, and
further preferably within a range of 10 to 40 weight %, with
respect to solid content of the photosensitive resin composition.
Note that, the solid content of the photosensitive resin
composition is defined as a total amount of all components included
in the photosensitive resin composition except for components such
as solvents which volatilizes in formation of the cured product
from the photosensitive resin composition. In addition, the resin
content of the photosensitive resin composition is defined as a
total amount of the component (A), the component (D), the component
(F1), and the component (F2) included in the photosensitive resin
composition.
[0106] Ingredients as described above for the photosensitive resin
composition are combined and kneaded by a known kneading method
using, for example, a three-roll, a ball mill, or a sand mill to
obtain the photosensitive resin composition.
[0107] In regard to preservation stability of the photosensitive
resin composition, some of the ingredients of the photosensitive
resin composition may be mixed to obtain a first mixture, and rest
of the ingredients may be mixed to obtain a second mixture. That
is, the photosensitive resin composition may include the first
mixture and the second mixture. For example, photopolymerizable
compounds, some of organic solvents, and epoxy compounds out of all
the ingredients may be mixed and dispersed in advance to obtain the
first mixture, and the rest of the ingredients may be mixed and
dispersed to obtain the second mixture. In this case, required
amounts of the first mixture and the second mixture may be mixed to
obtain a mixture which is used to form the cured product of the
photosensitive resin composition.
[0108] A solder resist composition according to the present
embodiment includes the photosensitive resin composition. The
solder resist composition may include the photosensitive resin
composition only. The solder resist composition is applied, for
example, to form a solder resist layer on a printed wiring
board.
[0109] Described below is an example of a method to form the solder
resist layer on the printed wiring board using the solder resist
composition according to the present embodiment. In this example, a
solder resist layer is formed with a solder resist composition
which has photocurability and thermosettability.
[0110] First, a printed wiring board is prepared, and a coating
film of the solder resist composition is formed on the printed
wiring board. For example, a surface of the printed wiring board is
coated with the solder resist composition to form the coating film
in a wet state (the wet coating film). A coating method to coat the
solder resist composition is selected from a group consisting of
known methods such as, for example, a dipping method, a spray
method, a spin coating method, a roll coating method, a curtain
coating method, and a screen printing method. Subsequently, if
necessary, in order for the organic solvent in the solder resist
composition to volatilize, the wet coating film is dried at a
temperature, for example, within a range of 60 to 120.degree. C. to
obtain the coating film after drying (the dry coating film). In the
present embodiment, tackiness of the dry coating film is suppressed
since the photopolymerization initiator includes three specific
kinds of components as described above.
[0111] Note that, in formation of the coating film on the printed
wiring board, the solder resist composition may be applied to an
appropriate supporting body and dried to form the dry coating film.
The dry coating film may be then stacked on the printed wiring
board, and pressure is applied to the dry coating film and the
printed wiring board to form the dry coating film on the printed
wiring board (a dry film method).
[0112] Subsequently, a negative mask is placed either directly or
indirectly on the dry coating film on the printed wiring board and
then light is irradiated to the negative mask so that the coating
film is exposed to light through the negative mask. The negative
mask includes an exposed part, which transmits light, and an
unexposed part, which does not transmit light. The exposed part of
the negative mask has a shape corresponding to a pattern shape of
the solder resist layer. For example, photo tools such as a mask
film and a dry plate are used as the negative mask. Light for
exposure is selected depending on composition of the solder resist
composition, and ultraviolet rays are used in the present
embodiment. A light source for ultraviolet rays is selected from a
group consisting of, for example, a chemical lamp, a low pressure
mercury lamp, a medium pressure mercury lamp, an ultra-high
pressure mercury lamp, a xenon lamp, a LED, and a metal halide
lamp.
[0113] Note that, a method which does not use a negative mask may
be employed as an exposure method. For example, a direct drawing
method such as laser exposure may be employed. An appropriate
printing method such as a screen printing method, an offset
printing method, and an ink jet printing method may also be used
for application of the solder resist composition to form an
appropriately patterned coating film which is then exposed to
light.
[0114] In the present embodiment, when the dry coating film is
exposed to ultraviolet rays, a photocuring reaction proceeds
efficiently in the dry coating film from its surface part to its
deep part.
[0115] After the dry coating film is exposed to light, the negative
mask is removed from the printed wiring board and then the dry
coating film undergoes a development process to remove the
unexposed part of the dry coating film. Accordingly, the exposed
part of the dry coating film remains as the solder resist layer on
a first surface and a second surface of the printed wiring
board.
[0116] In the development process, an appropriate developer
depending on the composition of the solder resist composition may
be used. Examples of the developer may include alkaline solutions
such as aqueous solutions of sodium carbonate, potassium carbonate,
ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen
carbonate, ammonium hydrogen carbonate, sodium hydroxide, potassium
hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, and
lithium hydroxide. Organic amines such as monoethanolamine,
diethanolamine, triethanolamine, monoisopropanolamine, di
isopropanolamine, and triisopropanolamine may be used as the
developer. Above described developers may be used alone or in
combination. When the developer is the alkaline solution, a solvent
of the alkaline solution may be water alone or may be a mixture of
water and a hydrophilic organic solvent such as lower alcohols.
[0117] When the solder resist composition includes a thermosetting
component, the solder resist layer may be thermosetted with heating
treatment, if necessary. As for conditions of the heating
treatment, for example, a heating temperature is within a range of
120 to 180.degree. C. and a heating period is within a range of 30
to 90 minutes. Accordingly, properties of the solder resist layer,
such as strength, hardness, and chemical resistance, are
improved.
[0118] Furthermore, after the solder resist layer undergoes the
heating treatment, the solder resist layer may be irradiated with
ultraviolet rays if necessary. In this case, the photocuring
reaction further proceeds in the solder resist layer. Accordingly,
migration resistance of the solder resist layer is further
improved.
[0119] As a result, a covered-printed wiring board which includes
the printed wiring board and the solder resist layer covering the
printed wiring board is obtained. In the present embodiment, the
solder resist layer can be cured from its surface part to its deep
part.
EXAMPLES
[0120] Hereinafter, examples of the present invention are
described. Note that, the present invention is not limited to
following examples.
[Preparation of a Photopolymerizable Compound]
(1) Preparation of a Photopolymerizable Oligomer A
[0121] 75 parts by mass of methacrylic acid, 85 parts by mass of
methyl methacrylate, 20 parts by mass of styrene, 20 parts by mass
of butyl methacrylate, 440 parts by mass of dipropylene glycol
monomethyl ether, and 5 parts by mass of azobisisobutyronitrile
were added to a four-neck flask attached with a reflux condenser, a
thermometer, a glass tube for nitrogen-substitution, and a stirrer.
A mixture in the four-neck flask was heated at 75.degree. C. for 5
hours under a nitrogen gas stream for a polymerization reaction to
proceed, resulting in a 31% copolymer solution.
[0122] 0.1 parts by mass of hydroquinone, 70 parts by mass of
3,4-epoxycyclohexylmethyl methacrylate, and 0.8 parts by mass of
dimethylbenzylamine were added to the copolymer solution and then
heated at 80.degree. C. for 24 hours for an addition reaction to
proceed. As a result, a 38% solution of a compound, which contains
a carboxyl group and an ethylene-based unsaturated group, was
obtained. The solution had 110 mgKOH/g of an acid value of a solid
component. The solution was defined as the photopolymerizable
oligomer A.
(2) Preparation of a Photopolymerizable Oligomer B
[0123] 70 parts by mass of methacrylic acid, 100 parts by mass of
methyl methacrylate, 30 parts by mass of t-butyl methacrylate, 440
parts by mass of dipropylene glycol monomethyl ether, and 5 parts
by mass of azobisisobutyronitrile were added to a four-neck flask
attached with a reflux condenser, a thermometer, a glass tube for
nitrogen-substitution, and a stirrer. A mixture in the four-neck
flask was heated at 75.degree. C. for 5 hours under a nitrogen gas
stream for a polymerization reaction to proceed, resulting in a 31%
copolymer solution.
[0124] 0.1 parts by mass of hydroquinone, 70 parts by mass of
3,4-epoxycyclohexylmethyl methacrylate, and 0.8 parts by mass of
dimethylbenzylamine were added to the copolymer solution and then
heated at 80.degree. C. for 24 hours for an addition reaction to
proceed. As a result, a 38% solution of a compound, which contains
a carboxyl group and an ethylene-based unsaturated group, was
obtained. The solution had 98 mgKOH/g of an acid value of a solid
component. The solution was defined as the photopolymerizable
oligomer B.
(3) Preparation of a Photopolymerizable Oligomer C
[0125] An acid-modified epoxy acrylate solution (Ripoxy PR-300CP,
concentration of 65%, manufactured by Showa Denko K.K.) was
prepared and used as the photopolymerizable oligomer C.
[Preparation of a Solder Resist Composition]
[0126] A mixture obtained by mixing components listed in tables
below was kneaded with a three-roll to obtain the solder resist
composition. Note that, details of the components listed in the
tables are as following. [0127] Photopolymerization initiator
(IRGACURE TPO): 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide,
manufactured by BASF, item No. IRGACURE TPO. [0128]
Photopolymerization initiator (IRGACURE 819):
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, manufactured by
BASF, item No. IRGACURE 819. [0129] Photopolymerization initiator
(IRGACURE MBF): (1,2-dioxo-2-methoxyethyl)benzene, manufactured by
BASF, item No. IRGACURE MBF. [0130] Photopolymerization initiator
(IRGACURE 754): a mixture of oxyphenylacetic acid
2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic acid
2-(2-hydroxyethoxy)ethyl ester, manufactured by BASF, item No.
IRGACURE 754. [0131] Photopolymerization initiator (IRGACURE 1173):
2-hydroxy-2-methyl-1-phenyl-propane-1-one, manufactured by BASF,
item No. IRGACURE 1173. [0132] Photopolymerization initiator
(IRGACURE 184): 1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by
BASF, item No. IRGACURE 184. [0133] Titanium dioxide CR-90: rutile
titanium dioxide manufactured with a chlorine method, manufactured
by ISHIHARA SANGYO KAISHA, LTD., item No. CR-90. [0134] Titanium
dioxide R-79: rutile titanium dioxide manufactured with a sulfuric
acid method, manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD.,
item No. R-79. [0135] Epoxy compound YDC-1312: a hydroquinone epoxy
compound represented by formula (1) (2,5-di-tert-butylhydroquinone
diglycidyl ether), manufactured by Nippon Steel & Sumikin
Chemical Co., Ltd., item No. YDC-1312, melting point at 145.degree.
C. [0136] Epoxy compound TGIC: triglycidyl isocyanurate
(1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H, 3H,
5H)-trione (a high melting point type)), melting point at
158.degree. C. [0137] EPICLON 850: bisphenol A epoxy resin,
manufactured by DIC Corporation, item No. EPICLON 850. [0138] 75%
solution of EHPE-3150: a 75% solution of
1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of
2,2-bis(hydroxymethyl)-1-butanol. [0139] Antioxidant IRGANOX 1010:
a hindered phenolic antioxidant, manufactured by BASF, item No.
IRGANOX 1010, melting point at 115.degree. C. [0140] Antioxidant
IRGANOX 1330: a hindered phenolic antioxidant, manufactured by
BASF, item No. IRGANOX 1330, melting point at 242.degree. C. [0141]
Organic solvent: methylpropylene diglycol, manufactured by Nippon
Nyukazai Co., Ltd., item No. MFDG. [0142] Photopolymerizable
monomer DPHA: dipentaerythritol hexaacrylate, manufactured by
Nippon Kayaku Co., Ltd., item No. KAYARAD DPHA. [0143]
Photopolymerizable monomer DPCA-60: caprolactone-modified
(meth)acrylate monomer, manufactured by Nippon Kayaku Co., Ltd.,
item No. KAYARAD DPCA-60. [0144] Defoaming agent: manufactured by
Shin-Etsu Chemical Co., Ltd., item No. KS-66. [0145] Melamine:
manufactured by NISSAN CHEMICAL INDUSTRIES, Ltd., fine-particulate
melamine.
[Evaluation Tests]
(1) Preparation of Test Pieces
[0146] A glass epoxy copper-clad laminated plate including a copper
foil with thickness of 35 .mu.m was prepared. A conductor wiring
was formed by etching on the glass epoxy copper-clad laminated
plate to obtain a printed wiring board. A surface of the obtained
printed wiring board was entirely coated with the solder resist
composition by a screen printing method and thereby a coating film
was formed. The coating film was heated at 80.degree. C. for 20
minutes and dried. Thickness of the coating film after drying (the
dry coating film) was 20 .mu.m. With a negative mask placed
directly on the dry coating film, the negative mask was irradiated
with ultraviolet rays with an exposing device equipped with a metal
halide lamp, and accordingly the dry coating film was selectively
exposed to light with 450 mJ/cm.sup.2 of exposure. Then, the
negative mask was removed from the dry coating film, and the dry
coating film was developed with a sodium carbonate aqueous solution
so that a part of the dry coating film, which was cured due to
exposure to light, remains as a solder resist layer on the printed
wiring board. The solder resist layer was further heated at
150.degree. C. for 60 minutes and thermosetted. As a result, a test
piece including the solder resist layer was obtained.
[0147] Following evaluation tests were carried out for each test
piece.
(2) Evaluation of Tackiness
[0148] In preparation of each test piece, when the negative mask
was removed from the dry coating film after exposure to light,
peeling resistance between the dry coating film and the negative
mask and a condition of the dry coating film after removal of the
negative mask were observed. The results were evaluated as
follows.
A: No stickiness was observed when the dry coating film before
exposure to light was touched with a finger, and no traces of the
negative mask were observed on the dry coating film after removal
of the negative mask succeeding to exposure to light. B: Slight
stickiness was observed when the dry coating film before exposure
to light was touched with a finger, and traces of the negative mask
were observed on the dry coating film after removal of the negative
mask succeeding to exposure to light. C: Conspicuous stickiness was
observed when the dry coating film before exposure to light was
touched with a finger, and the dry coating film was damaged after
removal of the negative mask succeeding to exposure to light.
(3) Evaluation of Remained Solder Dam
[0149] A printed wiring board including a copper conductor wiring
with line width of 0.2 mm, line interval of 0.3 mm, and thickness
of 40 .mu.m was prepared. A negative mask, which has a mask pattern
to form solder dams with four different widths of 50 .mu.m, 75
.mu.m, 100 .mu.m, and 125 .mu.m, was used. Under same conditions as
preparation of the test pieces other than using the above printed
wiring board and the above negative mask, a solder dam with
thickness of 40 .mu.m was formed on the printed wiring board.
[0150] Peeling test was carried out on the solder dam using a
cellophane adhesion tape, and a minimum width of remained solder
dam, which was not peeled off, on the printed wiring board was
measured. It is evaluated that the smaller the minimum width is,
the higher curing degree is in a deep part of the solder dam.
(4) Evaluation of Photosensitivity (Remained Steps)
[0151] A test mask for exposure to light (Step Tablet PHOTEC 21
steps manufactured by Hitachi Chemical Co., Ltd.) was directly
placed and attached by low pressure adhesion on the dry coating
film formed with a liquid solder resist composition of each example
and comparative example. Then, the dry coating film was irradiated
with ultraviolet rays with irradiation energy density of 450
mJ/cm.sup.2 through the test mask, using a both-side exposing
device of low pressure adhesion type manufactured by ORC
Manufacturing Co., Ltd. (model No. ORCHMW680GW) equipped with a
metal halide lamp. The dry coating film was then developed with a
developer (a sodium carbonate aqueous solution with concentration
of 1 weight %). Photosensitivity of the dry coating film was
evaluated in terms of the number of remained steps.
(5) Evaluation of Crack Resistance
[0152] Each test piece was cut off with a utility knife, and then
peeling test was carried out on the solder resist layer close to a
cut face using a cellophane adhesion tape. The solder resist layer
was observed after peeling test. The results were evaluated as
follows.
A: No crack was observed on the solder resist layer, and the solder
resist layer was not peeled off after peeling test using a
cellophane adhesion tape. B: Slight crack was observed on the
solder resist layer, but the solder resist layer was not peeled off
after peeling test using a cellophane adhesion tape. C: Substantial
crack was observed on the solder resist layer, but the solder
resist layer was not peeled off after peeling test using a
cellophane adhesion tape. D: The solder resist layer was peeled off
after peeling test using a cellophane adhesion tape.
(6) Evaluation of Surface Appearance
[0153] Surface appearance of the solder resist layer of each test
piece was observed visually. The results were evaluated as
follows.
A: No defect such as fine particles and bleeding was observed, and
a surface of the solder resist layer was uniform. B: Defect such as
fine particles and bleeding was observed, or a surface of the
solder resist layer was not uniform with unevenness and uneven
gloss.
(7) Evaluation of Solder Heat Resistance
[0154] A flux was applied on the solder resist layer of each test
piece using LONCO 3355-11 (a water-soluble flux manufactured by
London Chemical Co., Inc.). Succeedingly, each test piece was
dipped in a melted solder bath at 260.degree. C. for 10 seconds and
then rinsed with water, which is defined as one process. After the
process was carried out 3 times, surface appearance of the solder
resist layer was observed. The results were evaluated as
follows.
A: No change was observed. B: Very slight change was observed. C:
Slight change was observed. D: Substantial change such as peeling
of the solder resist layer was observed.
(8) Evaluation of Heat Discoloration Resistance
[0155] A b* value in L*a*b* color system was measured for the
solder resist layer of each test piece right after preparation,
using a spectral colorimeter manufactured by KONICA MINOLTA
SENSING, INC. (model No. CM-600d). Succeedingly, each test piece
was heated at 250.degree. C. for 5 minutes and then a b* value of
the solder resist layer was measured again. A value (.DELTA.b*) was
calculated by subtracting the b* value of the solder resist layer
before heating from the b* value of the solder resist layer after
heating. The results were evaluated as follows.
A: The .DELTA.b* value was less than 2.0. B: The .DELTA.b* value
was larger than or equal to 2.0 and less than 2.5. C: The .DELTA.b*
value was larger than or equal to 2.5 and less than 3.0. D: The
.DELTA.b* value was larger than or equal to 3.0.
(9) Evaluation of Light Discoloration Resistance
[0156] A b* value in L*a*b* color system was measured for the
solder resist layer of each test piece, using a spectral
colorimeter manufactured by KONICA MINOLTA SENSING, INC. (model No.
CM-600d). Succeedingly, the solder resist layer of each test piece
was irradiated with ultraviolet rays under a condition of 50
J/cm.sup.2 using an exposing device equipped with a metal halide
lamp, and then a b* value, in L*a*b* color system, of the solder
resist layer was measured again. A value (.DELTA.b*) was calculated
by subtracting the b* value of the solder resist layer before
ultraviolet irradiation from the b* value of the solder resist
layer after ultraviolet irradiation. The results were evaluated as
follows.
A: The .DELTA.b* value was less than 2.0. B: The .DELTA.b* value
was larger than or equal to 2.0 and less than 2.5. C: The .DELTA.b*
value was larger than or equal to 2.5 and less than 3.0. D: The
.DELTA.b* value was larger than or equal to 3.0.
(10) Reflectance
[0157] A stimulus value Y expressing luminous reflectance in CIE
color system was measured for the solder resist layer of each test
piece. The Y value is defines as an alternative characteristic of
reflectance. A spectral colorimeter manufactured by KONICA MINOLTA
SENSING, INC. with model No. CM-600d was used. For standardization,
a standard white surface with a known spectral reflectance factor
was used.
(11) Evaluation of Adhesion
[0158] Conforming to a test method of JIS D0202, the solder resist
layer of each test piece was cross-cut into a checker board pattern
and peeling test using a cellophane adhesion tape was carried out.
The solder resist layer after peeling test was observed visually.
The results were evaluated as following.
A: No change was observed in all of 100 cross-cut sections. B:
Floating of the solder resist layer was observed in one of 100
cross-cut sections. C: Peeling of the solder resist layer was
observed in 2 to 10 of 100 cross-cut sections. D: Peeling of the
solder resist layer was observed in 11 to 100 of 100 cross-cut
sections.
(12) Pencil Hardness
[0159] Pencil hardness of the solder resist layer of each test
piece was measured using Mitsubishi Hi-Uni pencils (manufactured by
Mitsubishi Pencil Co., Ltd.), conforming to JIS K5400.
TABLE-US-00001 TABLE 1 Examples 1 2 3 4 5 6 7 8 9 10 11 12 13
Composition/ Photopolymerizable oligomer A 80 80 80 80 80 80 80 80
80 80 80 80 80 parts by mass Photopolymerizable oligomer B
Photopolymerizable oligomer C Photopolymerization initiator 6
(IRGACURE TPO) Photopolymerization initiator 4 4 4 3 4 4 4 4 4 4 4
4 (IRGACURE 819) Photopolymerization initiator 10 10 10 10 5 10 10
10 10 10 10 10 (IRGACURE MBF) Photopolymerization initiator 15
(IRGACURE 754) Photopolymerization initiator 5 (IRGACURE 1173)
Photopolymerization initiator 6 (IRGACURE 184) Titanium dioxide
CR-90 60 60 30 60 60 60 60 60 60 60 60 60 Titanium dioxide R-79 30
60 Epoxy compound YDC-1312 15 15 15 15 15 15 15 15 10 15 Epoxy
compound TGIC 15 5 10 Epiclon 850 5 75% solution of EHPE-3150 20
Antioxidant IRGANOX 1010 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5
1.5 1.5 Antioxidant IRGANOX 1330 Organic solvent 10 10 10 10 10 10
10 10 10 10 10 10 10 Photopolymerizable monomer DPHA 5 5 5 5 5 5 5
5 5 5 5 5 10 Photopolymerizable monomer 5 5 5 5 5 5 5 5 5 5 5 5
DPCA-60 Defoamer 2 2 2 2 2 2 2 2 2 2 2 2 2 Melamine 2 2 2 2 2 2 2 2
2 2 2 2 2 Evaluation Tackiness A A A A B A A A A A B B A Remained
solder dam (.mu.m) 75 50 50 50 75 75 50 50 50 50 50 50 50
Photosensitivity 8 8 8 8 8 8 9 8 8 8 7 6 8 Crack resistance A A A B
A A A A C B C D A Surface appearance A A A A A A A A A A A A A
Solder heat resistance A A A A A A A A A A A A A Heat discoloration
resistance A A A C A A A A B A B A A Light discoloration resistance
A A A A A A A A B A B A A Reflectance 80 80 81 80 80 80 80 81 81 81
79 80 80 Adhesion A A A A A A A A A A A B A Pencil hardness 5H 5H
5H 5H 5H 5H 5H 5H 5H 5H 5H 4H 5H
TABLE-US-00002 TABLE 2 Examples Comperative Examples 14 15 16 17 18
19 20 1 2 3 4 5 6 Composition/ Photopolymerizable oligomer A 80 80
80 80 80 80 80 80 80 80 80 parts by mass Photopolymerizable
oligomer B 80 Photopolymerizable oligomer C 80 Photopolymerization
initiator 4 4 6 12 6 6 (IRGACURE TPO) Photopolymerization initiator
4 4 4 4 4 4 4 4 4 4 (IRGACURE 819) Photopolymerization initiator 10
10 10 10 10 5 10 15 (IRGACURE MBF) Photopolymerization initiator
(IRGACURE 754) Photopolymerization initiator 5 (IRGACURE 1173)
Photopolymerization initiator (IRGACURE 184) Titanium dioxide CR-90
60 60 60 60 60 60 60 60 60 60 60 60 60 Titanium dioxide R-79 Epoxy
compound YDC-1312 15 15 15 15 5 15 15 15 15 10 10 Epoxy compound
TGIC 15 5 15 5 5 Epiclon 850 75% solution of EHPE-3150 10
Antioxidant IRGANOX 1010 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5
1.5 Antioxidant IRGANOX 1330 0.3 1.5 Organic solvent 10 10 10 10 10
10 10 10 10 10 10 10 Photopolymerizable monomer DPHA 10 5 5 5 5 5 5
5 5 5 5 5 Photopolymerizable monomer 5 5 5 5 5 10 5 5 5 5 5 5
DPCA-60 Defoamer 2 2 2 2 2 2 2 2 2 2 2 2 2 Melamine 2 2 2 2 2 2 2 2
2 2 2 2 2 Evaluation Tackiness A A A A A A A A A A B A A Remained
solder dam (.mu.m) 75 50 50 50 50 75 75 125 100 50 125 50 50
Photosensitivity 8 8 8 9 10 8 7 5 10 6 5 9 9 Crack resistance C A A
A A B B A A A A B B Surface appearance A A A A A A A A A B A B B
Solder heat resistance A A A A A A A A A A A A A Heat discoloration
resistance A B A C A A A A A A A A A Light discoloration resistance
A A A C A A A A A A A A A Reflectance 80 80 80 76 80 80 80 79 80 79
78 80 80 Adhesion A A A A A A A A A A A A A Pencil hardness 5H 5H
5H 6H 5H 5H 5H 5H 5H 5H 5H 5H 5H
* * * * *