U.S. patent application number 13/139039 was filed with the patent office on 2011-10-06 for plating catalyst liquid, plating method, and method for producing laminate having metal film.
This patent application is currently assigned to FUJIFILM Corporation. Invention is credited to Hideo Nagasaki, Masataka Satou.
Application Number | 20110240482 13/139039 |
Document ID | / |
Family ID | 42268700 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110240482 |
Kind Code |
A1 |
Satou; Masataka ; et
al. |
October 6, 2011 |
PLATING CATALYST LIQUID, PLATING METHOD, AND METHOD FOR PRODUCING
LAMINATE HAVING METAL FILM
Abstract
A plating catalyst liquid which places little burden on the
environment, which does not roughen the surface of a plating
target, which can be easily controlled for the amount of plating
catalyst applied and which is at low risk of inflammation and is
highly safe, and a plating method using the plating catalyst are
provided. The plating catalyst liquid includes a palladium
compound, water, and a water-soluble combustible liquid serving as
a combustible liquid ingredient, has a flash point of 40.degree. C.
or more and contains the water-soluble combustible liquid in an
amount of 0.1 to 40 wt %.
Inventors: |
Satou; Masataka; (Kanagawa,
JP) ; Nagasaki; Hideo; (Kanagawa, JP) |
Assignee: |
FUJIFILM Corporation
Minato-ku, Tokyo
JP
|
Family ID: |
42268700 |
Appl. No.: |
13/139039 |
Filed: |
December 3, 2009 |
PCT Filed: |
December 3, 2009 |
PCT NO: |
PCT/JP2009/070307 |
371 Date: |
June 10, 2011 |
Current U.S.
Class: |
205/164 ;
205/183; 205/265 |
Current CPC
Class: |
C25D 7/00 20130101; C23C
18/30 20130101; C23C 18/1608 20130101; H05K 3/181 20130101; H05K
3/185 20130101; C23C 18/28 20130101; C23C 18/1653 20130101; C23C
18/405 20130101 |
Class at
Publication: |
205/164 ;
205/265; 205/183 |
International
Class: |
C25D 3/50 20060101
C25D003/50; C23C 28/00 20060101 C23C028/00; C25D 5/56 20060101
C25D005/56 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2008 |
JP |
2008-318600 |
Claims
1. A plating catalyst liquid comprising: a palladium compound;
water; and a water-soluble combustible liquid serving as a
combustible liquid ingredient, wherein the catalyst liquid has a
flash point of 40.degree. C. or more and contains the water-soluble
combustible liquid in an amount of 0.1 to 40 wt %.
2. The plating catalyst liquid according to claim 1, wherein the
water-soluble combustible liquid is a water-soluble organic solvent
having no primary or secondary hydroxyl group.
3. The plating catalyst liquid according to claim 1 which further
comprises an acid.
4. The plating catalyst liquid according to claim 1, wherein a
plating target is made of a hydrophobic resin having a functional
group capable of interacting with a plating catalyst or its
precursor.
5. The plating catalyst liquid according to claim 4, wherein the
hydrophobic resin is a cured product of a photosensitive resin
composition containing a polymer which has the functional group
capable of interacting with the plating catalyst or its precursor
and a polymerizable group.
6. The plating catalyst liquid according to claim 5, wherein the
polymer is a copolymer containing recurring units represented by
general formulas (1) and (2): ##STR00008## (in general formula (1),
R.sup.1 to R.sup.4 are each independently a hydrogen atom or an
optionally substituted alkyl group, Z and Y are each independently
a single bond or an optionally substituted divalent organic group,
and L.sup.1 is an optionally substituted divalent organic group,
and in general formula (2), R.sup.5 is a hydrogen atom or an
optionally substituted alkyl group, X is a single bond or an
optionally substituted divalent organic group, and L.sup.2 is an
optionally substituted divalent organic group).
7. A plating method comprising: a catalyst applying step for
applying a plating catalyst or its precursor to a plating target by
contacting the plating catalyst liquid according to claim 1 with
the plating target; and a plating step for plating the plating
target obtained in the catalyst applying step.
8. The plating method according to claim 7, wherein the plating
target is made of a hydrophobic resin having a functional group
capable of interacting with the plating catalyst or its
precursor.
9. The plating method according to claim 8, wherein the hydrophobic
resin is a cured product of a photosensitive resin composition
containing a polymer which has the functional group capable of
interacting with the plating catalyst or its precursor and a
polymerizable group.
10. The plating method according to claim 9, wherein the polymer is
a copolymer containing recurring units represented by general
formulas (1) and (2): ##STR00009## (in general formula (1), R.sup.1
to R.sup.4 are each independently a hydrogen atom or an optionally
substituted alkyl group, Z and Y are each independently a single
bond or an optionally substituted divalent organic group, and
L.sup.1 is an optionally substituted divalent organic group, and in
general formula (2), R.sup.5 is a hydrogen atom or an optionally
substituted alkyl group, X is a single bond or an optionally
substituted divalent organic group, and L.sup.2 is an optionally
substituted divalent organic group).
11. A method for producing a laminate having a metal film, the
method comprising: an application step in which a photosensitive
resin composition containing a polymer having a functional group
capable of interacting with a plating catalyst or its precursor and
a polymerizable group is applied onto a substrate to form a
photosensitive resin composition layer on the substrate; an
exposure step in which the photosensitive resin composition layer
is exposed in a pattern shape to form a patterned cured layer; a
development step in which part of the photosensitive resin
composition layer unexposed in the exposure step is removed; a
catalyst applying step in which the patterned cured layer obtained
in the development step is contacted with the plating catalyst
liquid according to claim 1 to apply the plating catalyst or its
precursor to the cured layer; and a plating step in which a plating
treatment is performed on the cured layer to which the plating
catalyst or its precursor was applied in the catalyst applying
step.
12. The method for producing a laminate having a metal film
according to claim 11, wherein the plating treatment in the plating
step is one in which electroless plating is followed by
electroplating.
13. The plating catalyst liquid according to claim 2 which further
comprises an acid.
14. The plating catalyst liquid according to claim 2, wherein a
plating target is made of a hydrophobic resin having a functional
group capable of interacting with a plating catalyst or its
precursor.
15. The plating catalyst liquid according to claim 3, wherein a
plating target is made of a hydrophobic resin having a functional
group capable of interacting with a plating catalyst or its
precursor.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plating catalyst liquid,
a plating method using the plating catalyst liquid and a method for
producing a laminate having a metal film with the use of the
plating catalyst liquid.
BACKGROUND ART
[0002] Recently, the technique of forming a metal film by plating
on a surface of a material has been utilized in various fields for
functional or decorative purposes. For example, the resin moldings
such as automobile parts are plated with metals such as copper and
nickel to add a touch of class and an aesthetic value thereto. In
addition, the technique of obtaining a desirably patterned metal
film after the formation of a metal film by plating on an
insulating film is widely used to manufacture electronic components
and semiconductor devices. This technique is used in, for example,
printed circuit boards employed in electronic devices and
electromagnetic interference shielding films employed in plasma
displays.
[0003] A "substractive" process and a "semi-additive" process are
used to manufacture materials having such a patterned metal
film.
[0004] The substractive process is a process in which a layer which
is photosensitive to irradiation with actinic rays is first
provided on a metal film formed on a surface of a substrate; the
photosensitive layer is then exposed imagewise and developed to
form a patterned resist image; the metal film in a region having no
resist image is then etched to form a metal pattern; and finally
the resist image is peeled off.
[0005] On the other hand, the semi-additive process is a process in
which a power supply layer is formed by any method on a surface of
a substrate such as an insulating resin film; a layer which is
photosensitive to irradiation with actinic rays is then formed on
the power supply layer; the photosensitive layer is exposed
imagewise and developed to form a patterned resist image;
electroplating is then performed as an electric current is flowed
through the power supply layer to form metal wiring in the
resist-free portions; and the part of the power supply layer having
no metal wiring is etched to form a metal pattern. The power supply
layer formed by this technique is formed by plating using a plating
catalyst liquid. This technique considerably reduces the amount of
metal removed by etching and is therefore capable of suppressing
excessive etching of the lateral surfaces of wiring as seen in the
subtractive process and is advantageous to form micro-wiring.
[0006] In the metal pattern formed by these processes, however, the
adhesion between the substrate and the metal film is achieved by
the anchor effect produced by forming irregularities at the surface
of the substrate. Therefore, when used as metal wiring, the metal
pattern suffered from poor radio frequency characteristics due to
the irregularities at the interface between the metal pattern and
the substrate. What is more, roughening of the substrate surface
required treatment of the substrate surface with a strong acid such
as chromic acid, which complicated the step and led to
environmental problems such as liquid waste disposal.
[0007] In order to solve these problems, a method for achieving a
strong adhesion with metal wiring while keeping a substrate surface
flat and smooth is proposed (Non-Patent Literature 1). More
specifically, this surface treatment involves performing a plasma
treatment on the substrate surface to introduce a polymerization
initiating group on the substrate surface and polymerizing a
monomer from the polymerization initiating group to form a surface
graft polymer having a polar group on the substrate surface. This
method enables the adhesion between the substrate and the metal
film to be improved without roughening the surface of the
substrate. On the other hand, the graft polymer has a polar group
in this method and therefore moisture is easily absorbed or removed
due to temperature or humidity changes and as a result the metal
film formed or the substrate may be deformed. In addition, in cases
where a substrate modified with such a polar group-containing graft
polymer is used to perform substrate metalization, a fault due to
water absorption in the electrical wiring manufacturing process and
an electrical fault of electrical wiring itself may occur.
[0008] In a method for obviating these problems, for example, a
hydrophobic substrate having a catalyst-adsorbing, hydrophobic
patterned resin layer formed thereon is preferably used as the
wiring substrate. In this case, a certain amount of the plating
catalyst liquid must permeate the catalyst-adsorbing, hydrophobic
patterned resin layer.
[0009] In this regard, use of a non-aqueous plating catalyst liquid
is proposed as a method of improving the plating properties while
keeping the hydrophobicity and surface flatness of a plating target
(Patent Literature 1). Patent Literature 1 discloses using as the
plating catalyst liquid a colloidal dispersion of a reduced metal
which is obtained by reducing a metal salt or a metal complex in a
mixed solution containing a lower alcohol and an aprotic polar
compound.
CITATION LIST
Patent Literature
[0010] Patent Literature 1: JP 1-315334 A
Non-Patent Literature
[0011] Non-Patent Literature 1: Advanced Materials, 2000, Vol. 12,
no. 20, 1481-1494
SUMMARY OF INVENTION
Technical Problems
[0012] However, the plating catalyst liquid containing a
non-aqueous solvent as described in Patent Literature 1 is an
aqueous inflammable liquid and therefore is at high risk of
inflammation and needs equipment which meets predetermined
requirements on the storage and handling. Particularly in the case
of high-volume industrial production, the foregoing plating
catalyst liquid requires huge capital investments and is not
preferred from the economical point of view. Use of a large
quantity of hazardous materials increases the environmental burdens
and is also not preferred to ensure the safety of workers.
[0013] The inventors of the invention have made an intensive study
and as a result found that use of the non-aqueous plating catalyst
liquid as described in Patent Literature 1 may hinder the control
of the amount of deposition on a hydrophobic plating target.
Therefore, the plating catalyst also adheres to unnecessary
portions during the formation of a patterned film by plating, which
may hinder the formation of a desired pattern.
[0014] In addition, the amount of deposits formed by plating was
also difficult to control in cases where the non-aqueous plating
catalyst liquid as described in Patent Literature 1 is used to form
the power supply layer upon the formation of wiring by the
foregoing semi-additive process. As a result, it was also found
that it may be difficult to remove catalyst or metal residues
having adhered to a plating target upon the removal of the power
supply layer by metal etching. Therefore, upon the formation of a
patterned film by plating, metal may remain between interconnects,
leading to a decrease in the insulation resistance, whereby desired
electrical characteristics cannot be obtained.
[0015] In view of the situation as described above, an object of
the invention is to provide a plating catalyst liquid which places
little burden on the environment, which does not roughen the
surface of a plating target, which can be easily controlled for the
amount of plating catalyst applied and which is at low risk of
inflammation and is highly safe. Another object of the invention is
to provide a plating method using the plating catalyst.
Solution to Problems
[0016] The inventors of the invention have made an intensive study
to achieve the objects and as a result found that the objects of
the invention are achieved by the characteristic features described
in (1) to (12) below. [0017] (1) A plating catalyst liquid
comprising: a palladium compound; water; and a water-soluble
combustible liquid serving as a combustible liquid ingredient,
wherein the catalyst liquid has a flash point of 40.degree. C. or
more and contains the water-soluble combustible liquid in an amount
of 0.1 to 40 wt %. [0018] (2) The plating catalyst liquid according
to (1), wherein the water-soluble combustible liquid is a
water-soluble organic solvent having no primary or secondary
hydroxyl group. [0019] (3) The plating catalyst liquid according to
(1) or (2) which further comprises an acid. [0020] (4) The plating
catalyst liquid according to any one of (1) to (3), wherein a
plating target is made of a hydrophobic resin having a functional
group capable of interacting with a plating catalyst or its
precursor. [0021] (5) The plating catalyst liquid according to (4),
wherein the hydrophobic resin is a cured product of a
photosensitive resin composition containing a polymer which has the
functional group capable of interacting with the plating catalyst
or its precursor and a polymerizable group. [0022] (6) The plating
catalyst liquid according to (5), wherein the polymer is a
copolymer containing recurring units represented by general
formulas (1) and (2):
##STR00001##
[0022] (in general formula (1), R.sup.1 to R.sup.4 are each
independently a hydrogen atom or an optionally substituted alkyl
group, Z and Y are each independently a single bond or an
optionally substituted divalent organic group, and L.sup.1 is an
optionally substituted divalent organic group, and in general
formula (2), R.sup.5 is a hydrogen atom or an optionally
substituted alkyl group, X is a single bond or an optionally
substituted divalent organic group, and L.sup.2 is an optionally
substituted divalent organic group). [0023] (7) A plating method
comprising:
[0024] a catalyst applying step for applying a plating catalyst or
its precursor to a plating target by contacting the plating
catalyst liquid according to any one of (1) to (3) with the plating
target; and
[0025] a plating step for plating the plating target obtained in
the catalyst applying step. [0026] (8) The plating method according
to (7), wherein the plating target is made of a hydrophobic resin
having a functional group capable of interacting with the plating
catalyst or its precursor. [0027] (9) The plating method according
to (8), wherein the hydrophobic resin is a cured product of a
photosensitive resin composition containing a polymer which has the
functional group capable of interacting with the plating catalyst
or its precursor and a polymerizable group. [0028] (10) The plating
method according to (9), wherein the polymer is a copolymer
containing recurring units represented by general formulas (1) and
(2):
##STR00002##
[0028] (in general formula (1), R.sup.1 to R.sup.4 are each
independently a hydrogen atom or an optionally substituted alkyl
group, Z and Y are each independently a single bond or an
optionally substituted divalent organic group, and L.sup.1 is an
optionally substituted divalent organic group, and in general
formula (2), R.sup.5 is a hydrogen atom or an optionally
substituted alkyl group, X is a single bond or an optionally
substituted divalent organic group, and L.sup.2 is an optionally
substituted divalent organic group). [0029] (11) A method for
producing a laminate having a metal film, the method
comprising:
[0030] an application step in which a photosensitive resin
composition containing a polymer having a functional group capable
of interacting with a plating catalyst or its precursor and a
polymerizable group is applied onto a substrate to form a
photosensitive resin composition layer on the substrate;
[0031] an exposure step in which the photosensitive resin
composition layer is exposed in a pattern shape to form a patterned
cured layer;
[0032] a development step in which part of the photosensitive resin
composition layer unexposed in the exposure step is removed;
[0033] a catalyst applying step in which the patterned cured layer
obtained in the development step is contacted with the plating
catalyst liquid according to (1) to (3) to apply the plating
catalyst or its precursor to the cured layer; and
[0034] a plating step in which a plating treatment is performed on
the cured layer to which the plating catalyst or its precursor was
applied in the catalyst applying step. [0035] (12) The method for
producing a laminate having a metal film according to (11), wherein
the plating treatment in the plating step is one in which
electroless plating is followed by electroplating.
Advantageous Effects of Invention
[0036] The invention can provide a plating catalyst liquid which
ensures high work safety, which places little burden on the
environment, which does not roughen the surface of a plating
target, and which can be highly controlled for the amount of
plating catalyst applied, thus leading to excellent wiring
formability, and which is not included in the hazardous materials
defined in the Category IV under the Fire Service Act, and a
plating method using the plating catalyst.
[0037] Particularly when containing an acid, the plating catalyst
has more improved storage stability. Use of a water-soluble organic
solvent having no primary or secondary hydroxyl group improves the
long-term storage stability of the plating catalyst liquid.
DESCRIPTION OF EMBODIMENTS
[0038] The plating catalyst liquid, the plating method using the
plating catalyst liquid and the method for producing a laminate
having a metal film with the use of the plating catalyst liquid
according to the invention are described below.
[0039] The plating catalyst liquid and the plating target for which
the catalyst liquid is used are first described.
[Plating Catalyst Liquid]
[0040] The plating catalyst liquid of the invention includes a
palladium compound, water, and a water-soluble combustible liquid
serving as a combustible liquid ingredient, has a flash point of
40.degree. C. or more and contains the water-soluble combustible
liquid in an amount of 0.1 to 40 wt % with respect to the total
amount of the catalyst liquid.
[0041] The respective materials for use in the plating catalyst
liquid are first described in detail.
[Palladium Compound]
[0042] The plating catalyst liquid of the invention contains a
palladium compound. The palladium compound serves as an active
nucleus during the plating treatment to deposit the metal and
functions as the plating catalyst (palladium) or its precursor
(palladium ion). The palladium compound is not particularly limited
as long as it contains palladium and serves as the nucleus during
the plating treatment. Examples thereof include a palladium (II)
salt, a palladium (0) complex and a palladium colloid.
[0043] Examples of the palladium (II) salt include palladium
acetate, palladium chloride, palladium nitrate, palladium bromide,
palladium carbonate, palladium sulfate,
bis(benzonitrile)dichloropalladium (II),
bis(acetonitrile)dichloropalladium (II) and
bis(ethylenediamine)palladium (II) chloride. Of these, palladium
nitrate, palladium acetate, palladium sulfate and
bis(acetonitrile)dichloropalladium (II) are preferred in terms of
the ease of handling and the solubility.
[0044] Examples of the palladium complex include a
tetrakis(triphenylphosphine)palladium complex and a
tris(benzylideneacetone)dipalladium complex.
[0045] The palladium colloid is composed of palladium (0)
particles. The particle size is not particularly limited and is
preferably from 5 to 300 nm and more preferably from 10 to 100 nm
in terms of the stability in the liquid. The palladium colloid may
optionally contain other metals such as tin. An example of the
palladium colloid includes a tin-palladium colloid. The palladium
colloid may be synthesized by any known method or a commercially
available product may be used. For example, the palladium colloid
can be prepared by reducing the palladium ion in a solution
containing a charged surfactant or a charged protective agent.
[0046] The content of the palladium compound in the plating
catalyst liquid is from 0.001 to 10 wt %, more preferably from 0.05
to 5 wt % and even more preferably from 0.10 to 1 wt % with respect
to the total amount of the catalyst liquid. At too low a content,
deposition is difficult to obtain in the plating to be described
later, whereas at too high a content, the patterned plating
properties and the etching residue removability to be described
later may be impaired.
[Water-Soluble Combustible Liquid]
[0047] The plating catalyst liquid of the invention contains a
water-soluble combustible liquid serving as the combustible liquid
ingredient. The water-soluble combustible liquid that may be used
in the plating catalyst liquid of the invention is not particularly
limited as long as it is a combustible solvent capable of mixing
with water at any ratio. Examples thereof include water-soluble
organic solvents such as a ketone solvent, an ester solvent, an
alcoholic solvent, an ether solvent, an amine solvent, a thiol
solvent and a halogen solvent.
[0048] Examples of the ketone solvent include
4-hydroxy-4-methyl-2-pentanone, .gamma.-butyrolactone and
hydroxyacetone.
[0049] Examples of the ester solvents include
2-(2-ethoxyethoxy)ethyl acetate, ethylene glycol monomethyl ether
acetate, diethylene glycol monoethyl ether acetate, methyl
cellosolve acetate, 2-hydroxyethyl acrylate, hydroxypropyl
acrylate, methyl glycolate, and ethyl glycolate.
[0050] Examples of the alcoholic solvent include ethanol, isopropyl
alcohol, normal propyl alcohol, 3-acetyl-1-propanol,
2-(allyloxy)ethanol, 2-aminoethanol, 2-amino-2-methyl-1-propanol,
(.+-.)-2-amino-1-propanol, 3-amino-1-propanol,
2-dimethylaminoethanol, 2,3-epoxy-1-propanol, ethylene glycol,
2-fluoroethanol, diacetone alcohol, 2-methylcyclohexanol,
4-hydroxy-4-methyl-2-pentanone, glycerol,
2,2',2''-nitrilotriethanol, 2-pyridine methanol,
2,2,3,3-tetrafluoro-1-propanol, 2-(2-aminoethoxy)ethanol,
2-[2-(benzyloxy)ethoxy]ethanol, 2,3-butanediol, 2-butoxyethanol,
2,2'-thiodiethanol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol,
2-methyl-2,4-pentanediol, 1,3-propanediol, diglycerol,
2,2'-methyliminodiethanol and 1,2-pentanediol.
[0051] Examples of the ether solvent include
bis(2-ethoxyethyl)ether, bis[2-(2-hydroxyethoxy)ethyl]ether,
1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether,
bis(2-methoxyethyl)ether, 2-(2-butoxyethoxy)ethanol,
2-[2-(2-chloroethoxy)ethoxy)ethanol, 2-ethoxyethanol,
2-(2-ethoxyethoxy)ethanol, 2-isobutoxyethanol,
2-(2-isobutoxyethoxy)ethanol, 2-isopropoxyethanol,
2-[2-(2-methoxyethoxy)ethoxy]ethanol, 2-(2-methoxyethoxy)ethanol,
1-ethoxy-2-propanol, 1-methoxy-2-propanol, tripropylene glycol
monomethyl ether, methoxyacetic acid and 2-methoxyethanol.
[0052] Examples of the glycol solvent include diethylene glycol,
triethylene glycol, ethylene glycol, hexaethylene glycol, propylene
glycol, dipropylene glycol and tripropylene glycol.
[0053] Examples of the amine solvent include N-methyl-2-pyrrolidone
and N,N-dimethylformamide.
[0054] Examples of the thiol solvent include mercaptoacetic acid
and 2-mercaptoethanol.
[0055] Examples of the halogen solvent include 3-bromobenzyl
alcohol, 2-chloroethanol and 3-chloro-1,2-propanediol.
[0056] Exemplary other water-soluble organic solvents that may be
used include those illustrated in the table below.
TABLE-US-00001 TABLE 1 Acrylic acid 2-(Dimethylamino)ethyl acrylate
Acetyl methyl carbinol 1-Amino-4-methylpiperazine
Pyridine-3-aldehyde Isobutyric acid Aluminum ethylacetoacetate
diisopropylate (water-soluble) Ethyl glycol Ethylene glycol
monobutyl ether Ethylene chlorohydrin N-Ethylmorpholine
Ethylenediamine 3-Ethoxypropylamine Formic acid (at least 86%)
Isoamyl formate Acetic acid 1,4-Diaminobutane 1,2-Diaminopropane
1,3-Diaminopropane 3-Diethylaminopropylamine
N,N-Diethylethanolamine Cyclohexylamine N,N-Dimethylacetamide
Di-n-butoxy-bis(triethanolaminato)titanium Dimethylaminopropylamine
2-(Dimethylamino)acetoaldehyde dimethyl acetal
N,N-Dimethylethanolamine 2,5-Dimethylpyrazine Pyrethrum (protection
of stored grain) Hydrazine hydrate (up to 79%) (emulsion) Sodium
alcoholate (liquid) Tetramethy1-1,3-diaminopropane Sodium methoxide
1,1,3-trihydrotetrafluoropropanol Ethyl lactate Methyl lactate
.alpha.-Picoline .beta.-Picoline .gamma.-Picoline Hydrazine (up to
79%) Proprionic acid Propylene chlorohydrin Benzylaminopurine (3%
emulsion) Trimethyl borate Methylaminopropylamine
N-Methylpiperazine 2-Methylpyrazine 3-Methoxypropylamine
2-Mercaptoethanol Morpholine Diethylenetriamine
N,N-dimethylacrylamide Dimethylaminopropyl methacrylamide
Dimethylsulfoxide N,N-Dimethylaminopropyl acrylamide
(-)-D-Diisopropyl tartrate Hydrazine hydrate (at least 80%)
Sulfolane (anhydrous type is solid and Thioglycolic acid
nonhazardous) Thiodiglycol Tetraethylenepentamine n-Tetradecane
N,N,N',N'-Tetramethy1-1,6-hexamethylenediamine Triethyl phosphate
(TEP) Triethylene glycol Triethylenetetramine Trimethyl phosphate
d-Valelolactone Bis(aminopropyl)piperazine Hydrazine (at least 80%)
2-Hydroxyethyl acrylate 2-Hydroxyethylaminopropylamine Hydroxyethyl
piperazine 4-Hydroxy-2-butanone
Vinyltris(.beta.-methoxyethoxy)silane 2-Pyridinemethanol
3-Pyridinemethanol 4-Pyridinemethanol Pyruvic acid Phenethylamine
Formamide 1,3-Butanediol 1,4-Butanediol Butyl diglycol
.gamma.-butyrolactone Furfuryl alcohol Hexylene glycol Benzylamine
Pentaethylenehexamine Polyethylene glycol diglycidyl ether (n = 13
or less) Polypropylene glycol diglycidyl ether (n = 11 or less)
Methacrylic acid 2-Hydroxyethyl methacrylate
Methyliminobispropylamine N-Methylethanolamine
N-Methyl-N,N-diethanolamine 3-Methyl-3-methoxybutyl acetate
.beta.-Mercaptopropionic acid Ethylene glycol monoacetate
[0057] The water-soluble combustible liquid of the invention
preferably has a boiling point of 80 to 200.degree. C. and more
preferably 100 to 200.degree. C. in terms of easier removal of the
water-soluble combustible liquid from the plating target to be
described later and the stability of the catalyst liquid
composition kept by the evaporation of a solvent. Preferred
examples of the water-soluble combustible liquid include
1-acetoxy-2-methoxyethane with a boiling point of 145.degree. C.,
bis(2-ethoxyethyl)ether with a boiling point of 188.degree. C. and
bis(2-methoxyethyl)ether with a boiling point of 162.degree. C.
[0058] The content of the water-soluble combustible liquid in the
plating catalyst liquid of the invention is preferably from 0.1 to
40 wt % and more preferably from 5 to 40 wt % with respect to the
total amount of the catalyst liquid in terms of the permeability of
the plating target to be described later.
[0059] A preferred embodiment of the water-soluble combustible
liquid of the invention is a water-soluble organic solvent having
no primary or secondary hydroxyl group. Use of the water-soluble
organic solvent having no primary or secondary hydroxyl group
(preferably an ether solvent having no primary or secondary
hydroxyl group) further suppresses the discoloration of the
solution while further enhancing the storage stability of the
plating catalyst. Use of a water-soluble organic solvent having a
primary or secondary hydroxyl group is likely to cause the hydroxyl
group to undergo an oxidation reaction due to the palladium
compound during the long-term storage to be converted to ketone
group, aldehyde group or carboxylic group, thus leading to the
discoloration of the solution.
[0060] Examples of the water-soluble organic solvent having no
primary or secondary hydroxyl group include
4-hydroxy-4-methyl-2-pentanone, 2-(2-ethoxyethoxy)ethyl acetate,
1-acetoxy-2-methoxyethane, bis(2-ethoxyethyl)ether,
1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether,
bis(2-methoxyethyl)ether, 2-(dimethylamino)ethyl acrylate and
1-amino-4-methylpiperazine.
[0061] In particular, the water-soluble organic solvent is
preferably also free from tertiary alcohol having few concerns
about the oxidation in terms of the storage stability of the
catalyst liquid, and preferred examples thereof include
2-(2-ethoxyethoxy)ethyl acetate, 1-acetoxy-2-methoxyethane,
bis(2-ethoxyethyl)ether (also called diethylene glycol diethyl
ether), 1,2-bis(2-methoxyethoxy)ethane,
bis[2-(2-methoxyethoxy)ethyl]ether and bis(2-methoxyethyl)ether
(also called diethylene glycol dimethyl ether).
[0062] The plating catalyst liquid containing the water-soluble
combustible liquid that may be used in the invention has a flash
point of at least 40.degree. C. The water-soluble combustible
liquid for use in the plating catalyst liquid is preferably
selected from among those having a flash point of at least
30.degree. C., more preferably at least 40.degree. C. and even more
preferably at least 60.degree. C. Within the foregoing range, the
plating catalyst liquid has a higher flash point to further improve
the work safety.
[Water]
[0063] The plating catalyst liquid of the invention contains water.
By incorporating water in the plating catalyst liquid, the
permeation rate of the plating catalyst or its precursor through
the hydrophobic plating target is controlled within a preferred
range. The water used is preferably free from impurities. Reverse
osmosis (RO) water, deionized water, distilled water and purified
water are preferably used, and deionized water and distilled water
are more preferred.
[0064] The optimal content of water in the plating catalyst liquid
of the invention is appropriately selected and the water content is
preferably from 35 to 99.899 wt % and more preferably from 35 to 95
wt % with respect to the total amount of the catalyst liquid.
[0065] The plating catalyst liquid of the invention containing the
foregoing ingredients is less flammable and highly safe. The highly
safe catalyst liquid as used herein refers to one which has a flash
point of at least 40.degree. C. and a fire point of at least
60.degree. C. at 1 atm and which contains the combustible liquid in
an amount of up to 40 wt % with respect to the total amount of the
catalyst liquid.
[0066] The flash point of the plating catalyst liquid of the
invention refers to a value of measurement obtained by the Tag
closed cup method according to JIS-K2265.
[0067] The plating catalyst liquid of the invention preferably has
a fire point of at least 60.degree. C. The fire point is the lowest
temperature at which a combustible liquid or solid continues to
burn when a small flame is moved closer thereto. The fire point is
usually higher by at least 20.degree. C. than the flash point.
[0068] The fire point can be determined by the measurement
according to the Tag closed cup method (JIS-K2265).
[Acid]
[0069] The plating catalyst liquid of the invention further
contains an acid. By incorporating an acid in the plating catalyst
liquid, the solubility of the palladium compound in the liquid is
further improved and the storage stability is also dramatically
improved.
[0070] Examples of the acid include nitric acid, hydrochloric acid,
sulfuric acid, acetic acid and citric acid. Of these, nitric acid,
hydrochloric acid and sulfuric acid are preferred in terms of more
excellent solubility of the palladium compound and more excellent
stability of the liquid. These acids may be used alone or in
combination of two or more.
[0071] The content of the acid in the plating catalyst liquid of
the invention is preferably from 1 to 40 wt % and more preferably
from 10 to 25 wt % with respect to the total amount of the catalyst
liquid. At too high a content, deposits may not be uniformly formed
by plating. At too low a content, adverse effects of the acid, that
is, problems such as unimproved solubility and poor stability of
the liquid may occur.
[0072] The plating catalyst liquid described above may contain
other additives according to the intended purpose as long as the
effects of the invention are not impaired. Exemplary other
additives include swelling agents (e.g., organic compounds such as
ketones, aldehydes, ethers and ethers), and surfactants (e.g.,
low-molecular-weight or high-molecular-weight, anionic, cationic,
amphoteric or nonionic surfactants). In the case of using an
organic compound for the swelling agent, it is preferred to select
a compound which does not impair the effects of the invention.
[Plating Target]
[0073] The plating target of the plating catalyst liquid of the
invention is not particularly limited and is preferably a
hydrophobic resin. A specific example of the plating target
includes a hydrophobic resin which has a functional group capable
of interacting with the plating catalyst or its precursor. The
functional group is hereinafter also referred to as "interactive
group." The specific shape of the hydrophobic resin serving as the
plating target is not particularly limited and an optimal shape is
suitably selected according to the intended purpose. A plate or a
film made of an interactive group-containing hydrophobic resin may
be used. Alternatively, a substrate to which an interactive
group-containing hydrophobic resin is applied may be used.
[0074] The hydrophobic resin is not particularly limited as long as
it has low affinity for water and repels water. Examples of the
hydrophobic resin include polyimide resins, epoxy resins, acrylic
resins, liquid crystal polymers, polycarbonates, ABS,
polypropylenes and polytetrafluoroethylenes.
[0075] The interactive group is a functional group capable of
interacting with the plating catalyst or its precursor, more
specifically palladium metal or palladium ion derived from the
palladium compound.
[0076] The interactive group is preferably a non-dissociative
functional group. The non-dissociative functional group refers to a
functional group in which no proton is generated by dissociation.
The functional group has the function of interacting the plating
catalyst or its precursor but does not have high water
absorbability or high hydrophilicity unlike the dissociative polar
group (hydrophilic group). Therefore, a hydrophobic film which has
high resistance to permeation of an alkaline developer can be
formed from a polymer having the functional group.
[0077] More specifically, the interactive group is preferably
selected from among a group capable of forming a coordination bond
with a metal ion, a nitrogen-containing functional group, a
sulfur-containing functional group and an oxygen-containing
functional group. More specific examples thereof include
nitrogen-containing functional groups such as imide group, pyridine
group, tertiary amino group, ammonium group, pyrrolidone group,
amidino group, triazine ring, triazole ring, benzotriazole group,
benzimidazole group, quinoline group, pyrimidine group, pyrazine
group, nazoline group, quinoxaline group, purine group, triazine
group, piperidine group, piperazine group, pyrrolidine group,
pyrazole group, aniline group, alkylamine group
structure-containing group, isocyanuric structure-containing group,
nitro group, nitroso group, azo group, diazo group, azide group,
cyano group, and cyanate group (R--O--CN); oxygen-containing
functional groups such as phenolic hydroxyl group, hydroxyl group,
carbonate group, ether group, carbonyl group, ester group, N-oxide
structure-containing group, S-oxide structure-containing group and
N-hydroxy structure-containing group; sulfur-containing functional
groups such as thiophene group, thiol group, thiocyanuric acid
group, benzothiazole group, mercaptotriazine group, thioether
group, thioxy group, sulfoxide group, sulfone group, sulfite group,
sulfoximine structure-containing group, sulfoxinium salt
structure-containing group and sulfonic ester structure-containing
group; phosphorus-containing functional groups such as phosphate
group, phosphoramide group and phosphine group; groups containing
halogen atoms such as chlorine and bromine; and unsaturated
ethylene group. In an embodiment showing no dissociation because of
the relation with the neighboring atom or atom group, imidazole
group, urea group or thiourea group may be used.
[0078] Of these, ether group (more specifically a structure
represented by --O--(CH.sub.2).sub.n--O-- (n is an integer of 1 to
5)) or cyano group is particularly preferred and cyano group is
more preferred in terms of high polarity and high adsorptivity on a
plating catalyst or its precursor.
[0079] In addition, a compound capable of forming a complex such as
an inclusion compound, cyclodextrin or crown ether may be applied
instead of the functional groups.
[0080] The interactive group is more preferably an alkylcyano
group. The aromatic cyano group withdraws the electron from the
aromatic ring and the unpaired electron donating ability which is
important for the adsorption onto the plating catalyst or its
precursor is rather low, whereas the alkylcyano group is not
attached to the aromatic ring and is therefore preferred in terms
of the adsorption onto the plating catalyst or its precursor.
[0081] The weight-average molecular weight (Mw) of the interactive
group-containing hydrophobic resin is not particularly limited and
is preferably from 1,000 to 700,000 and more preferably from 2,000
to 300,000. It is particularly preferred for the weight-average
molecular weight to be at least 20,000 in terms of the
polymerization sensitivity.
[0082] The degree of polymerization is preferably 10 or more and
more preferably 20 or more, but is preferably up to 7,000, more
preferably up to 3,000, even more preferably up to 2,000 and most
preferably up to 1,000.
[Photosensitive Resin Composition]
[0083] A preferred example of the interactive group-containing
hydrophobic resin of the invention includes a cured product of a
photosensitive resin composition which contains a polymer having a
functional group capable of interacting with the plating catalyst
or its precursor and a polymerizable group.
[0084] The cured product of the photosensitive resin composition is
obtained by curing the photosensitive resin composition under
exposure to energy rays such as UV rays and electron rays. Curing
may be performed by a common method under exposure to energy rays
such as UV rays. For example, in the case of exposure to UV rays,
UV light generators such as a low-pressure mercury vapor lamp, a
high-pressure mercury vapor lamp, a ultrahigh pressure mercury
lamp, a xenon lamp and a UV-emitting laser (excimer lamp) may be
used. Specific conditions include those of exposure performed in
the exposure step in the method for producing a laminate having a
metal film to be described later.
[0085] In cases where the photosensitive resin composition contains
a solvent as will be described later, a desired cured product is
obtained by a method which involves applying the photosensitive
resin composition to a substrate to form a film, optionally
removing the solvent in a step provided for drying and irradiating
the film with the energy rays as described above. The substrate
that is preferably used is one which has the function of forming a
direct chemical bond with a polymer having a functional group
capable of interacting with the plating catalyst or its precursor
and a polymerizable group.
[0086] The ingredients contained in the photosensitive resin
composition are described below in detail.
[Polymer Having Functional Group Capable of Interacting with
Plating Catalyst or its Precursor and Polymerizable Group]
[0087] The photosensitive resin composition contains a polymer
having a functional group capable of interacting with the plating
catalyst or its precursor and a polymerizable group. The functional
group and the polymer are hereinafter also referred to as
"interactive group" and "specific polymerizable polymer",
respectively. Inclusion of the polymerizable group enables the
formation of a bond between polymers and a bond between a polymer
and a substrate (graft polymerization).
[0088] The interactive group is a functional group capable of
interacting with the plating catalyst or its precursor, more
specifically palladium metal or palladium ion derived from the
palladium compound. The interactive group is as defined above for
the hydrophobic resin and the preferable range is also the
same.
[0089] The polymerizable group the specific polymerizable compound
has is a functional group capable of bonding polymers each having a
polymerizable group and an interactive group or bonding a polymer
having a polymerizable group and an interactive group with a
substrate to be described later. Specific examples thereof include
vinyl group, vinyloxy group, allyl group, acryloyl group,
methacryloyl group, oxetane group, epoxy group, isocyanate group,
an active hydrogen-containing functional group and an active group
in an azo compound.
[0090] The specific polymerizable polymer that may be used in the
invention is preferably a polymer obtained by introducing an
ethylenically addition-polymerizable unsaturated group
(polymerizable group) such as vinyl group, allyl group or
(meth)acryl group in a homopolymer or copolymer obtained using an
interactive group-containing monomer. The polymer having a
polymerizable group and an interactive group has the polymerizable
group at least at the end of the main chain or on the side chain
and preferably on the side chain.
[0091] When one or both of acryl and methacryl are denoted in the
specification, acryl and methacryl may be collectively written as
"(meth)acryl."
[0092] Monomers other than the interactive group-containing monomer
may be used in the formation of the specific polymerizable polymer
to reduce the water absorbability and improve the hydrophobicity.
Examples of the monomer used with the interactive group-containing
monomer include general polymerizable monomers such as diene
monomer and acrylic monomer. Of these, unsubstituted alkyl acrylate
monomers are preferred. More specifically, tert-butyl acrylate,
2-ethylhexyl acrylate, butyl acrylate, cyclohexyl acrylate and
benzyl methacrylate can be preferably used.
[0093] The specific polymerizable polymer preferably contains the
recurring unit derived from the interactive group-containing
monomer in an amount of 30 to 90 mol % and more preferably 40 to 80
mol % with respect to all the recurring units (100 mol %) of the
polymer in terms of the interaction formed with the plating
catalyst or its precursor.
[0094] The weight-average molecular weight (Mw) of the specific
polymerizable polymer is not particularly limited and is preferably
from 1,000 to 700,000 and more preferably from 2,000 to 300,000. It
is particularly preferred for the weight-average molecular weight
to be at least 20,000 in terms of the polymerization
sensitivity.
[0095] The degree of polymerization is preferably 10 or more and
more preferably 20 or more, but is preferably up to 7,000, more
preferably up to 3,000, even more preferably up to 2,000 and most
preferably up to 1,000.
[0096] In the practice of the invention, a preferred example of the
specific polymerizable polymer includes a copolymer containing
recurring units represented by general formulas (1) and (2). This
polymer is hereinafter also referred to as "cyano group-containing
polymerizable polymer."
##STR00003##
(In general formula (1), R.sup.1 to R.sup.4 are each independently
a hydrogen atom or an optionally substituted alkyl group, Z and Y
are each independently a single bond or an optionally substituted
divalent organic group, and L.sup.1 is an optionally substituted
divalent organic group, and in general formula (2), R.sup.5 is a
hydrogen atom or an optionally substituted alkyl group, X is a
single bond or an optionally substituted divalent organic group,
and L.sup.2 is an optionally substituted divalent organic
group.)
[0097] R.sup.1 to R.sup.4 in general formula (1) and R.sup.5 in
general formula (2) are each a hydrogen atom or an optionally
substituted alkyl group. Examples of the unsubstituted alkyl group
include methyl group, ethyl group, propyl group and butyl group.
Examples of the substituted alkyl group include methyl group, ethyl
group, propyl group and butyl group substituted with methoxy group,
hydroxy group, chlorine atom, bromine atom or fluorine atom.
[0098] R.sup.1 is preferably a hydrogen atom or a methyl group
optionally substituted with a hydroxy group or a bromine atom.
[0099] R.sup.2 is preferably a hydrogen atom or a methyl group
optionally substituted with a hydroxy group or a bromine atom.
[0100] R.sup.3 is preferably a hydrogen atom.
[0101] R.sup.4 is preferably a hydrogen atom.
[0102] R.sup.5 is preferably a hydrogen atom, or a methyl group
optionally substituted with a hydroxy group or a bromine atom.
[0103] Y and Z in general formula (1) and X in general formula (2)
are each a single bond or an optionally substituted divalent
organic group. Examples of the divalent organic group include an
optionally substituted aliphatic hydrocarbon group, an optionally
substituted aromatic hydrocarbon group, an ester group, an amide
group, an ether group and combination groups thereof.
[0104] Preferred examples of the optionally substituted aliphatic
hydrocarbon group include methylene group, ethylene group,
propylene group and butylene group optionally substituted with
methoxy group, hydroxy group, chlorine atom, bromine atom or
fluorine atom.
[0105] Preferred examples of the optionally substituted aromatic
hydrocarbon group include phenyl group optionally substituted with
methoxy group, hydroxy group, chlorine atom, bromine atom or
fluorine atom. Of these, --(CH.sub.2).sub.n-- where n is an integer
of 1 to 3 is preferred and --CH.sub.2-- is more preferred.
[0106] In general formula (1), L.sup.1 is an optionally substituted
divalent organic group. The organic groups represented by L.sup.1
are the same as the organic groups represented by Y and Z in
general formula (1).
[0107] L.sup.1 is preferably a divalent organic group having a
urethane bond or a urea bond and more preferably a divalent organic
group having a urethane bond. L.sup.1 even more preferably contains
in total 1 to 9 carbon atoms. The total number of carbon atoms in
L.sup.1 refers to the total number of carbon atoms included in the
optionally substituted divalent organic group represented by
L.sup.1.
[0108] More specifically, L.sup.1 preferably has a structure
represented by general formula (1-1) or (1-2).
##STR00004##
[0109] In general formulas (1-1) and (1-2), R.sup.a and R.sup.b are
each independently a divalent organic group formed with at least
two atoms selected from the group consisting of carbon atom,
hydrogen atom and oxygen atom. Preferred examples thereof include
optionally substituted methylene, ethylene, propylene and butylene
groups, ethylene oxide group, diethylene oxide group, triethylene
oxide group, tetraethylene oxide group, dipropylene oxide group,
tripropylene oxide group, and tetrapropylene oxide group.
[0110] In general formula (2), L.sup.2 is an optionally substituted
divalent organic group. The organic groups represented by L.sup.2
are the same as the organic groups represented by X in general
formula (2).
[0111] In particular, L.sup.2 is preferably a linear, branched or
cyclic alkylene group, an aromatic group, or a combination group
thereof. The alkylene group may be further combined with the
aromatic group via an ether group, an ester group, an amide group,
a urethane group or a urea group. Of these, L.sup.2 preferably
contains in total 1 to 15 carbon atoms and is most preferably
unsubstituted. The total number of carbon atoms in L.sup.2 refers
to the total number of carbon atoms included in the optionally
substituted divalent organic group represented by L.sup.2.
[0112] Specific examples thereof include methylene group, ethylene
group, propylene group, butylene group and phenylene group which
may be optionally substituted with methoxy group, hydroxy group,
chlorine atom, bromine atom or fluorine atom, and combination
groups thereof.
[0113] In the cyano group-containing polymerizable monomer of the
invention, the recurring unit represented by general formula (1) is
preferably a recurring unit represented by general formula (3):
##STR00005##
wherein R.sup.2 and R.sup.2 are each independently a hydrogen atom
or an optionally substituted alkyl group, Z is a single bond or an
optionally substituted divalent organic group, W is an oxygen atom
or NR (where R is a hydrogen atom or an alkyl group and preferably
a hydrogen atom or an unsubstituted alkyl group having 1 to 5
carbon atoms), and L.sup.2 is an optionally substituted divalent
organic group.
[0114] R.sup.1 and R.sup.2 in general formula (3) are as defined
above for R.sup.1 and R.sup.2 in general formula (1) and the
preferred examples are also the same.
[0115] Z in general formula (3) is as defined above for Z in
general formula (1) and the preferred examples are also the same.
L.sup.1 in general formula (3) is as defined above for L.sup.1 in
general formula (1) and the preferred examples are also the
same.
[0116] In the cyano group-containing polymerizable polymer of the
invention, the recurring unit represented by general formula (3) is
preferably a recurring unit represented by general formula (4):
##STR00006##
wherein R.sup.1 and R.sup.2 are each independently a hydrogen atom
or an optionally substituted alkyl group. V and W are each
independently an oxygen atom or NR (where R is a hydrogen atom or
an alkyl group and preferably a hydrogen atom or an unsubstituted
alkyl group having 1 to 5 carbon atoms), and L.sup.1 is an
optionally substituted divalent organic group.
[0117] R.sup.1 and R.sup.2 in general formula (4) are as defined
above for R.sup.1 and R.sup.2 in general formula (1) and the
preferred examples are also the same. L.sup.1 in general formula
(4) is as defined above for L.sup.1 in general formula (1) and the
preferred examples are also the same.
[0118] In general formulas (3) and (4), W is preferably an oxygen
atom.
[0119] In formulas (3) and (4), L.sup.1 is preferably an
unsubstituted alkylene group or a divalent organic group having a
urethane bond or a urea bond, more preferably a divalent organic
group having a urethane bond, and most preferably contains in total
1 to 9 carbons.
[0120] In the cyano group-containing polymerizable polymer of the
invention, the recurring unit represented by general formula (2) is
preferably a recurring unit represented by general formula (5):
##STR00007##
wherein R.sup.5 is a hydrogen atom or an optionally substituted
alkyl group, U is an oxygen atom or NR' (where R' is a hydrogen
atom or an alkyl group and preferably a hydrogen atom or an
unsubstituted alkyl group having 1 to 5 carbon atoms), and L.sup.2
is an optionally substituted divalent organic group.
[0121] R.sup.5 in general formula (5) is as defined for R.sup.1 and
R.sup.2 in general formula (1) and is preferably a hydrogen
atom.
[0122] L.sup.2 in general formula (5) is as defined for L.sup.2 in
general formula (2) and is preferably a linear, branched or cyclic
alkylene group, an aromatic group, or a combination group
thereof.
[0123] Particularly in general formula (5), an embodiment in which
the linkage moiety of L.sup.2 with the cyano group is a divalent
organic group having a linear, branched or cyclic alkylene group is
preferred and an embodiment in which the divalent organic group
contains in total 1 to 10 carbon atoms is more preferred.
[0124] In another preferred embodiment, the linkage moiety of
L.sup.2 with the cyano group in general formula (5) is a divalent
organic group having an aromatic group and the divalent organic
group more preferably contains in total 6 to 15 carbon atoms.
[0125] The type of polymerization reaction in the synthesis of the
cyano group-containing polymerizable polymer according to the
invention is not particularly limited. Examples thereof include
radical polymerization, cationic polymerization and anionic
polymerization. Radical polymerization and cationic polymerization
are preferably used in terms of the reaction control. The synthesis
method is described in detail in paragraphs [0196] to [0243] of WO
2008-050715.
[0126] In the foregoing cyano group-containing polymerizable
polymer, the ratio of the polymerizable group-containing recurring
unit and that of the cyano group-containing recurring unit with
respect to the whole of the copolymer ingredients are preferably
within the following ranges.
[0127] More specifically, the content of the polymerizable
group-containing recurring unit is preferably from 5 to 50 mol %
and more preferably from 5 to 40 mol % with respect to the whole of
the copolymer ingredients (100 mol %). At too low a content, the
reactivity (curing properties, polymerizability) may be reduced,
whereas at too high a content, gelation is more likely to occur and
may often hinder the synthesis.
[0128] The content of the cyano group-containing recurring unit is
preferably from 5 to 95 mol %, more preferably from 10 to 95 mol %
and even more preferably from 50 to 95 mol % with respect to the
whole of the copolymer ingredients (100 mol %) in terms of the
adsorption of the plating catalyst.
[0129] The weight-average molecular weight (Mw) of the cyano
group-containing polymerizable polymer is not particularly limited
and is preferably from 1,000 to 700,000 and more preferably from
2,000 to 200,000. It is particularly preferred for the
weight-average molecular weight to be at least 20,000 in terms of
the polymerization sensitivity.
[0130] The degree of polymerization of the cyano group-containing
polymerizable polymer is preferably 10 or more and more preferably
20 or more but is preferably up to 7,000, more preferably up to
3,000, even more preferably up to 2,000 and most preferably up to
1,000.
[0131] Specific examples of the cyano group-containing
polymerizable polymer include those described in paragraphs [0246]
to [0252] of WO 2008-050715.
[0132] The above-described specific polymerizable polymer such as
the cyano group-containing polymerizable polymer may contain a
polar group as long as the effects of the invention are not
impaired.
[0133] The content of the specific polymerizable polymer in the
photosensitive resin composition is not particularly limited and is
preferably from 2 to 50 wt % and more preferably from 5 to 20 wt %
with respect to the total amount of the composition in terms of the
ease of handling.
[Solvent]
[0134] The photosensitive resin composition may contain a
solvent.
[0135] The solvent is not particularly limited as long as the
above-described specific polymerizable polymer which is the main
ingredient of the composition is soluble therein.
[0136] Examples of the solvent include alcoholic solvents such as
methanol, ethanol, propanol, ethylene glycol, glycerol and
propylene glycol monomethyl ether; acids such as acetic acid;
ketone solvents such as acetone, methyl ethyl ketone and
cyclohexanone; amide solvents such as formamide, dimethylacetamide
and N-methylpyrrolidone; nitrile solvents such as acetonitrile and
propionitrile; ester solvents such as methyl acetate and ethyl
acetate; and carbonate solvents such as dimethyl carbonate and
diethyl carbonate.
[0137] Particularly in cases where the above-described cyano
group-containing polymerizable polymer is used as the specific
polymerizable polymer, amide solvents, ketone solvents, nitrile
solvents and carbonate solvents are preferred, and more
specifically acetone, dimethylacetamide, methyl ethyl ketone,
cyclohexanone, acetonitrile, propionitrile, N-methylpyrrolidone and
dimethyl carbonate are preferred.
[0138] In the case of applying the photosensitive resin
composition, the solvent preferably has a boiling point of 50 to
150.degree. C. in terms of the ease of handling. These solvents may
be used alone or in combination of two or more.
[0139] In cases where the photosensitive resin composition is
applied to the substrate, a solvent having a ratio of solvent
absorption into the substrate, or the polymerization initiation
layer or adhesion promoting layer on the substrate of 5 to 25% may
be selected. The ratio of solvent absorption can be determined from
the weight change of the substrate or the substrate having the
polymerization initiation layer which was pulled up 1,000 minutes
after the immersion in a solvent.
[0140] In cases where the photosensitive resin composition is
applied to the substrate, a solvent having a substrate swelling
ratio of 10 to 45% may also be selected. The swelling ratio can be
determined from the thickness change of the substrate or the
substrate having the polymerization initiation layer or the
adhesion promoting layer which was pulled up 1,000 minutes after
the immersion in a solvent.
[Additives]
[0141] The photosensitive resin composition may optionally contain
various additives. Exemplary additives include a surfactant, a
plasticizer, a polymerization inhibitor, a rubber ingredient, a
flame retardant, a diluent, a thixotropic agent, a pigment, an
antifoaming agent, a leveling agent, and a coupling agent. More
specifically, surfactants, plasticizers and polymerization
inhibitors described in paragraphs [0125] to [0127] of WO
2008-050715 may be used.
[Plating Method]
[0142] Next, the plating method using the above-described plating
catalyst liquid is described. The plating method of the invention
is not particularly limited but a plating method including the
following steps is preferred: [0143] (1) a catalyst applying step
for applying the plating catalyst or its precursor to a plating
target by contacting the above-described plating catalyst liquid
with the plating target; and [0144] (2) a plating step for plating
the plating target obtained in the catalyst applying step.
[0145] Each step is described in detail below.
[Catalyst Applying Step]
[0146] The catalyst applying step is a step in which the foregoing
plating catalyst liquid is contacted with the plating target to
apply palladium (plating catalyst) or palladium ion (precursor)
derived from the palladium compound to the plating target. As a
result of this step, the plating catalyst liquid permeates the
plating target and the plating catalyst or its precursor which
serves as the nucleus in the plating treatment is applied
(adsorbed) to the plating target.
[0147] As described above, a liquid containing a palladium
compound, water and a water-soluble combustible liquid serving as
the combustible liquid ingredient is used as the plating catalyst
liquid. As described above, the plating target which is preferably
used is made of an interactive group-containing hydrophobic resin
(and is preferably in the form of a substrate) or is a laminate
having a substrate and a layer made of an interactive
group-containing hydrophobic resin.
[0148] Use of the plating catalyst liquid of the invention to treat
the hydrophobic plating target (interactive group-containing
hydrophobic resin) further facilitates the control of the amount of
deposition of palladium serving as the plating catalyst.
[0149] In other words, in the case of a conventional plating
catalyst liquid containing a non-aqueous solvent, the permeability
of the plating catalyst liquid to the hydrophobic plating target
and the degree of application of the plating catalyst were too high
and the amount of deposition was difficult to control.
Consequently, the plating catalyst was deposited on a region of the
plating target where the plating catalyst should not be essentially
deposited. In a process which involves forming a metal film (e.g.,
power supply layer) by electroless plating using the plating
catalyst and thereafter etching unnecessary portions of the metal
film for metalization, more plating catalyst than necessary may be
applied because of the difficulty in removing the metal residues
including the plating catalyst from the plating target and the
conventional plating catalyst liquid was not preferred in terms of
the application to electronic components.
[0150] On the other hand, in the case of the plating catalyst
liquid of the invention, the plating catalyst slowly permeates the
hydrophobic plating target and therefore the amount of deposition
is easy to control, and the plating catalyst can be deposited to a
desired amount by controlling, for example, the contact time
between the plating catalyst liquid and the plating target. The
plating catalyst of the invention is applied (adsorbed) slowly to
the plating target which has no functional group capable of
interacting with the plating catalyst or its precursor. Therefore,
significantly good pattern plating can be performed in a plating
target including an area having no functional group capable of
interacting with the plating catalyst or its precursor and an area
having a functional group capable of interacting with the plating
catalyst or its precursor.
[0151] In addition, the catalyst liquid contains water and
therefore cannot permeate the interior of the plating target
quickly but be efficiently adsorbed to a surface layer area of the
plating target with a thickness of several tens of nanometers. In
this way, metal residues including the plating catalyst can be
easily removed from the plating target in the semi-additive
process.
[0152] The process of contacting the plating catalyst liquid with
the plating target is not particularly limited and exemplary
processes include one in which the plating catalyst liquid is
applied to the surface of the plating target and one in which the
plating target is immersed in the plating catalyst liquid.
[0153] In cases where a cured film of the foregoing photosensitive
resin composition is formed as desired on each surface of the
substrate, the immersion process is preferably used to
simultaneously contact the cured layers present on both sides with
the plating catalyst liquid. In the immersion, the plating target
is preferably immersed in the plating catalyst liquid as it is
stirred or shaken in order to keep the concentration of the
catalyst near the surface of the plating target in contact with the
catalyst.
[0154] In cases where the cured product of the photosensitive resin
composition including the interactive group-containing specific
polymerizable polymer is used, the plating catalyst (palladium) can
be efficiently adsorbed onto the interactive group (e.g., cyano
group) included in the cured product by means of the interaction
based on the intermolecular force such as van der Waals force or
the interaction based on the coordination bond using lone-pair
electrons.
[0155] As for the contact time between the plating catalyst liquid
and the plating target, optimal conditions are selected as
appropriate for the type of the plating target used and the
materials of the plating catalyst liquid. The contact time is
preferably from about 30 seconds to about 1 hour and more
preferably from about 1 minute to about 30 minutes in terms of the
productivity and workability.
[0156] As described above, use of the plating catalyst of the
invention enables the deposition of extra plating catalyst into the
plating target to be suppressed. More specifically, the amount of
palladium (plating catalyst) deposited (adsorbed) into the plating
target is preferably from 1 to 100 mg/m.sup.2, more preferably from
5 to 50 mg/m.sup.2 and even more preferably from 5 to 30
mg/m.sup.2. When the amount of deposition is too large, the
insulation performance may be reduced in cases where the plating
target is used for a printed circuit board, or it may be difficult
to remove catalyst metal upon formation of interconnects using
metal etching according to the subtractive process or semi-additive
process. When the amount of deposition is too small, precipitation
for forming a film by plating as described below may often not take
place well.
[0157] The amount of deposition (adsorption) of palladium serving
as the plating catalyst can be determined by a process which
involves adsorbing the plating catalyst onto a plating target with
a certain area, quantifying the palladium concentration by a mass
spectrometer (ICP-MS) and dividing the resulting amount of
adsorption by the area to measure the amount of deposition in terms
of milligram per square meter (mg/m.sup.2).
[0158] The catalyst applying step may be optionally followed by a
step of cleaning the plating target (cleaning step) in order to
remove extra plating catalyst deposited onto the plating
target.
[0159] The solution for use in the cleaning is not particularly
limited as long as it does not adversely affect the step to be
described below, and a cleaning solution containing water as the
main solvent and also containing an organic solvent in an amount of
0.5 to 40 wt % is more preferably used in terms of the removal
efficiency.
[Plating Step]
[0160] The plating step is a step for plating the plating target
obtained in the catalyst applying step. Plating treatment is
performed to form a film (metal film) on the plating target. The
film formed by plating has excellent electrical conductivity and
excellent adhesion to the plating target.
[0161] Examples of the type of plating performed in this step
include electroless plating and electroplating, and the type may be
selected as appropriate for the function of the plating catalyst or
its precursor. Of these, electroless plating is preferably
performed in terms of improving the formability of a hybrid
structure in the plating target and the adhesion. Electroless
plating may also be followed by electroplating so that the film
obtained by plating may have a desired thickness.
[Electroless Plating]
[0162] Electroless plating refers to an operation with which metal
is precipitated by a chemical reaction using a solution in which
metal ions to be precipitated by plating are dissolved.
[0163] Electroless plating in this step is performed by cleaning
the plating target having the plating catalyst applied thereto with
water to remove extra plating catalyst (metal) and immersing the
cleaned plating target in the electroless plating bath. A commonly
known electroless plating bath may be used for electroless
plating.
[0164] In cases where the plating target having the plating
catalyst precursor applied thereto is immersed in the electroless
plating bath with the plating catalyst precursor adsorbed onto or
impregnated in the plating target, the plating target is immersed
in the electroless plating bath after the removal of extra
precursor (e.g., metal salt) by cleaning with water. In this case,
reduction of the plating catalyst precursor and the subsequent
electroless plating are performed in the electroless plating bath.
A commonly known electroless plating bath may be used for
electroless plating.
[0165] Reduction of the plating catalyst precursor can also be
performed as a separate step preceding electroless plating by
preparing a catalyst activating solution (reducing solution)
instead of the embodiment using the electroless plating solution as
described above. The catalyst activating solution is a solution
containing a reducing agent which can reduce the plating catalyst
precursor (mainly metal ion) to a zero-valent metal. The
concentration of the reducing agent with respect to the total
solution is generally in a range of 0.1 wt % to 50 wt % and
preferably 1 wt % to 30 wt %. Examples of the reducing agent that
may be used include boron reducing agents such as sodium
borohydride and dimethylaminoborane, formaldehyde and
hypophosphorous acid.
[0166] In addition to the solvent, the general composition of the
electroless plating bath mainly includes (1) a metal ion for
plating, (2) a reducing agent, and (3) an additive for enhancing
the stability of the metal ion (stabilizer). In addition to these
ingredients, this plating bath may also include known additives
such as a stabilizer for the plating bath.
[0167] The solvent for use in this plating bath preferably contains
an organic solvent which has high affinity for the plating target
with low water absorbability and high hydrophobicity. The type and
content of organic solvent may be adjusted according to the
physical properties of the plating target.
[0168] The organic solvent that may be used in the plating bath is
preferably a water-soluble solvent, and a water-soluble flammable
liquid making up the catalyst liquid of the invention may be used.
Examples of the solvent that may be preferably used include ketones
such as acetone, and alcohols such as methanol, ethanol, and
isopropanol.
[0169] Copper, tin, lead, nickel, gold, palladium and rhodium are
known metals that may be used in the electroless plating bath. Of
these, copper and gold are particularly preferred in terms of the
electrical conductivity.
[0170] A reducing agent and additives are selected as appropriate
for the metal used. For example, the electroless copper plating
bath contains a copper salt (CuSO.sub.4), a reducing agent (HCOH)
and additives such as a copper ion stabilizer (EDTA), a chelating
agent (Rochelle salt) and a trialkanolamine.
[0171] The plating bath that may be used in the electroless CoNiP
plating contains metal salts (cobalt sulfate and nickel sulfate), a
reducing agent (sodium hypophosphite), and a complexing agent such
as sodium malonate, sodium malate or sodium succinate.
[0172] The electroless palladium plating bath contains a metallic
ion ((Pd(NH.sub.3).sub.4)Cl.sub.2), reducing agents (NH.sub.3,
H.sub.2NNH.sub.2) and a stabilizer (EDTA).
[0173] These plating baths may contain ingredients other than the
above.
[0174] Commercial products may be used for the plating liquid as
exemplified by THRU-CUP PGT available from C. Uyemura & Co.,
Ltd., and ATS Addcopper IW available from Okuno Chemical Industries
Co., Ltd.
[0175] The thickness of the film formed by electroless plating may
be controlled by adjusting the metal ion concentration in the
plating bath, the immersion time in the plating bath, and the
temperature of the plating bath. The film thickness is preferably
at least 0.1 .mu.m and more preferably 0.1 to 1 .mu.m in terms of
the electrical conductivity. However, in cases where the film
formed by electroless plating is used as the electrical conduction
layer (power supply layer) to perform electroplating to be
described below, a film with a thickness of at least 0.1 .mu.m
should be formed uniformly.
[0176] The time of immersion in the plating bath is preferably from
about 1 minute to about 6 hours and more preferably from about 1
minute to about 3 hours.
[0177] The cross-sectional surface of the film obtained as above by
electroless plating is observed by a scanning electron microscope
(SEM) and it is confirmed that the plating catalyst and the plating
metal microparticles are dispersed at a high density in the plating
target and particularly in the vicinity of its surface and the
metal is further deposited on the plating target. Since the
interface between the plating target and the film formed by plating
is in a hybrid state of the plating target and the microparticles,
good adhesion is achieved even when the interface between the
plating target (organic ingredient) and the inorganic substance
(catalyst metal or plating metal) is flat and smooth (for example,
a 1 mm.sup.2-region has a surface roughness R.sub.a of up to 100
nm).
[Electroplating]
[0178] In this step, in cases where the plating catalyst or its
precursor applied in the catalyst applying step functions as the
electrode, the plating target to which the plating catalyst or its
precursor is applied can be subjected to electroplating.
[0179] The foregoing electroless plating may be followed by
electroplating using the film formed by electroless plating as the
electrode. In this way, a new film with a desired thickness can be
easily formed based on the film which was formed by electroless
plating and which has good adhesion to the plating target. The film
with a thickness suitable to the intended purpose can be formed by
electroplating following electroless plating and therefore the
metal film of the invention (film formed by plating) can be
advantageously used in various applications.
[0180] Any conventionally known method may be used for
electroplating. Examples of the metal that may be used in
electroplating in this step include copper, chromium, lead, nickel,
gold, silver, tin, and zinc. In terms of the electrical
conductivity, copper, gold and silver are preferred and copper is
more preferred.
[0181] The thickness of the film (metal film) obtained by
electroplating can be controlled by adjusting the concentration of
the metal contained in the plating bath, current density or the
like. When used in general electrical wiring, the film preferably
has a thickness of at least 0.5 .mu.m and more preferably from 1
.mu.m to 100 .mu.m in terms of the electrical conductivity.
However, the thickness of wiring is reduced with decreasing line
width of the wiring or with miniaturization in order to maintain
the aspect ratio. Therefore, the thickness of the film formed by
electroplating is not limited to the above-defined range but may be
arbitrarily set.
[0182] In the invention, a metal or a metal salt derived from the
plating catalyst or its precursor, and/or a metal deposited in the
plating target by electroless plating is formed in the plating
target as a fractal microstructure, whereby the adhesion between
the film formed by plating and the plating target can be further
improved.
[0183] The ratio of metal in the region within a depth from the
uppermost surface of the plating target of 0.5 .mu.m is 5 to 50
area % in a cross-sectional image of the plating target taken with
a metallograph to determine the amount of metal present in the
plating target, and the interface between the plating target and
the film formed by plating has an arithmetic mean roughness R.sub.a
(ISO 4288 (1996)) of 0.01 to 0.5 .mu.m. Even in such a flat and
smooth interface, strong adhesion is achieved between the plating
target and the metal film.
[0184] The plating target including a metal film formed thereon by
the above steps (film formed by plating) has good adhesion to the
metal film and may be used in various applications. Exemplary
applications include electromagnetic wave protecting films, coating
films, two-layer copper clad laminate (CCL) materials and electric
wiring materials.
[0185] The film obtained by plating may also be etched in a pattern
shape to form a metal pattern.
[Method for Producing Laminate Having Metal Film]
[0186] Next, the method for producing a laminate having a metal
film using the foregoing plating catalyst liquid is described. The
method for producing the laminate having the metal film according
to the invention is not particularly limited but a production
method mainly including: [0187] (1) a layer-forming step in which a
photosensitive resin composition containing a polymer having a
functional group capable of interacting with a plating catalyst or
its precursor and a polymerizable group is used to form a
photosensitive resin composition layer on a substrate; [0188] (2)
an exposure step in which the photosensitive resin composition
layer is exposed in a pattern shape to form a cured layer in the
exposed area; [0189] (3) a development step in which part of the
photosensitive resin composition layer unexposed in the exposure
step is removed; [0190] (4) a catalyst applying step in which the
patterned cured layer obtained in the development step is contacted
with the foregoing plating catalyst liquid to apply the plating
catalyst or its precursor to the cured layer; and [0191] (5) a
plating step in which the cured layer to which the plating catalyst
or its precursor was applied in the catalyst applying step is
plated is preferred.
[0192] Each step is described in detail below.
[Layer-Forming Step]
[0193] The layer-forming step is a step in which a photosensitive
resin composition containing a polymer having a functional group
capable of interacting with a plating catalyst or its precursor and
a polymerizable group is used to form a photosensitive resin
composition layer on a substrate. More specifically, it is a step
in which a photosensitive resin composition layer is formed on a
substrate by applying a photosensitive resin composition to the
substrate or immersing the substrate in the photosensitive resin
composition.
[0194] The above-described polymers and materials are used for the
polymer having a functional group capable of interacting with the
plating catalyst or its precursor and a polymerizable group
(specific polymerizable polymer) and for the photosensitive resin
composition, respectively.
[0195] The substrate used is described below.
[Substrate]
[0196] The substrate may have the function of forming direct
chemical bonding with the specific polymerizable polymer. More
specifically, the substrate itself may have such surface
properties. Alternatively, an intermediate layer separately formed
on the substrate may have such properties.
[0197] The substrate that may be used in the invention is
preferably a dimensionally stable sheet. Examples thereof include
paper; paper laminated with plastic materials such as polyethylene,
polypropylene and polystyrene; metal sheets made of, for example,
aluminum, zinc and copper; plastic films made of, for example,
cellulose diacetate, cellulose triacetate, cellulose propionate,
cellulose butyrate, cellulose acetate, cellulose nitrate,
polyethylene terephthalate, polyethylene, polystyrene,
polypropylene, polycarbonate, polyvinyl acetal, polyimide, epoxy,
bismaleimide resin, polyphenylene oxide, liquid crystal polymer,
polytetrafluoroethylene, ABS, NBR, acrylic polymer, olefin polymer,
and polyester resin; and paper or plastic films on which any of the
foregoing metals is laminated or vapor-deposited, epoxy or
polyimide films impregnated with glass cloth; and interlayer
dielectric films for use in multilayer circuit boards (containing
as the ingredient glass filler-containing epoxy or polyimide,
polyamide-imide, or liquid crystal polymer). In addition, the
substrate used may be made of inorganic materials such as glass and
ceramic materials.
[0198] These substrates may be prepared by mixing inorganic fillers
such as silica in terms of improving the dimensional stability and
the physical properties. Of these, a substrate containing a resin
selected from among epoxy resin, polyimide resin and liquid crystal
polymer is preferred.
[0199] In cases where the substrate surface has the function of
forming direct chemical bonding with the specific polymerizable
polymer, the intermediate layer (adhesion promoting layer) to be
described later is not necessary.
[0200] A substrate which contains polyimide having a polymerization
initiation moiety in the skeleton as described in paragraphs [0028]
to [0088] of JP 2005-281350 A may also be used in the
invention.
[0201] A substrate made of an insulating resin and a substrate
having an insulating resin layer formed on the surface thereof may
also be used in the invention. Use of such a substrate enables the
resulting substrate having a metal film formed thereon to be
advantageously employed in semiconductor packages and various
electrical circuit boards.
[0202] A known insulating resin composition is used to obtain a
substrate or a film made of the insulating resin. In addition to
the resin as the main ingredient, the insulating resin composition
may further contain various additives according to the intended
purpose. For example, a polyfunctional acrylate monomer is added to
enhance the strength of the insulating layer, inorganic or organic
particles are added to enhance the strength of the insulating layer
and improve the electrical properties, and other means can be
applied.
[0203] The "insulating resin" as used in the invention refers to a
resin having sufficient insulating properties to enable the use in
known insulating films and insulating layer, and may be applied to
the invention even if it is not a complete insulator as long as it
has the insulating properties suitable to the purpose.
[0204] Specific examples of the insulating resin include a
thermosetting resin, a thermoplastic resin and a mixture thereof.
For example, epoxy resin, phenol resin, polyimide resin, polyester
resin, bismaleimide resin, polyolefin resin, isocyanate resin,
phenoxy resin, polyethersulfone, polysulfone, polyphenylene
sulfone, polyphenylene sulfide, polyphenyl ether and polyetherimide
as described in paragraphs [0014] to [0019] of JP 2007-144820 A may
be used. The insulating resins described in paragraphs [0066] to
[0073] of WO 2008-050715 may also be used.
[0205] Taking into account the application to semiconductor
packages and various electrical circuit boards, the substrate
preferably has a surface roughness of up to 500 nm, more preferably
up to 100 nm, even more preferably up to 50 nm and most preferably
up to 20 nm. The lower limit is preferably as small as possible and
more preferably 0 nm. The surface roughness of the substrate (the
surface roughness of the intermediate layer and the adhesion
promoting layer when they are formed), is preferably as small as
possible because the electrical loss during the RF power
transmission is reduced in cases where the resulting patterned
metal material is applied to wiring.
[0206] The adhesion promoting layer to be described below may also
be formed on the substrate to improve the adhesion between the
substrate and the cured layer of the photosensitive resin
composition.
[Adhesion Promoting Layer]
[0207] Resin compositions having good adhesion to the substrate and
active species (compounds) which may generate active points capable
of interacting with the resin film formed of the photosensitive
resin composition are preferably used to form the adhesion
promoting layer. In cases where the resin making up the resin
composition has a moiety where an active point capable of
interacting with the resin film having metal ion adsorptivity is
generated, it is not necessary to separately add the active species
(compounds).
[0208] In cases where the substrate is made of a known insulating
resin having been used as a material of a multilayer laminate, a
build-up substrate, or a flexible substrate, the insulating resin
composition (e.g., insulating resin) is preferably used for the
adhesion promoting layer in terms of the adhesion to the
substrate.
[0209] The insulating resin composition for use in forming the
adhesion promoting layer may contain the same or different resin as
or from the electrical insulating resin making up the substrate. It
is particularly preferred to use a resin whose thermophysical
properties such as glass transition point, modulus of elasticity
and coefficient of linear expansion are close to those of the resin
making up the substrate. More specifically, it is preferred to use,
for example, the same type of insulating resin as that making up
the substrate in terms of the adhesion.
[0210] In addition to this ingredient, inorganic or organic
particles may be added to enhance the strength of the adhesion
promoting layer and improve the electrical properties.
[0211] The insulating resin for use in the adhesion promoting layer
refers to a resin having sufficient insulating properties to enable
the use in known insulating films, and may be applied to the
invention even if it is not a complete insulator as long as it has
the insulating properties suitable to the purpose.
[0212] Specific examples of the insulating resin include a
themosetting resin, a thermoplastic resin and a mixture thereof.
Examples of the thermoplastic resin include epoxy resin, phenol
resin, polyimide resin, polyester resin, bismaleimide resin,
polyolefin resin, and isocyanate resin.
[0213] Examples of the thermoplastic resin include phenoxy resin,
polyethersulfone, polysulfone, polyphenylene sulfone, polyphenylene
sulfide, polyphenyl ether and polyetherimide.
[0214] A resin having a skeleton which may generate active points
where the resin may form an interaction with the photosensitive
resin composition may also be used as the insulating resin for use
in the adhesion promoting layer. For example, polyimides having a
polymerization initiation moiety in the skeleton as described in
paragraphs [0018] to [0078] of JP 2005-307140 A are used.
[0215] Various compounds may be added to the composition of the
adhesion promoting layer according to the intended purpose as long
as the effects of the invention are not impaired.
[0216] Specific examples include substances capable of reducing the
stress during heating such as rubber and SBR latex, a binder for
improving the film properties, a plasticizer, a surfactant, and a
viscosity modifier.
[0217] Composite materials of the resins and other ingredients may
also be used for the adhesion promoting layer in order to enhance
the properties of the resin film such as mechanical strength, heat
resistance, weather resistance, flame resistance, water resistance,
and electrical characteristics. Exemplary materials that may be
used to obtain the composite materials include paper, glass fiber,
silica particles, phenol resin, polyimide resin, bismaleimide
triazine resin, fluororesin and polyphenylene oxide resin.
[0218] In addition, the adhesion promoting layer may optionally
include at least one filler used in a common resin material for
circuit boards. The filler is selected from among, for example,
inorganic fillers such as silica, alumina, clay, talc, aluminum
hydroxide and calcium carbonate and organic fillers such as cured
epoxy resin, cross-linked benzoguanamine resin and cross-linked
acrylic polymer. Of these, silica is preferably used as the
filler.
[0219] The adhesion promoting layer may optionally further include
at least one of various additives such as colorant, flame
retardant, adhesion promoter, silane coupling agent, antioxidant
and UV absorber.
[0220] Each of these materials is preferably added in a range of 0
to 200 wt % and more preferably 0 to 80 wt % with respect to the
resin which is the main ingredient. In cases where the adhesion
promoting layer and its adjoining substrate show physical values
identical to or close to each other under the action of heat or
electricity, the additives may not be added. In cases where the
additives are used in amounts exceeding 200 wt % with respect to
the resin, there is concern that the properties such as the
strength the resin itself essentially has may be reduced.
[0221] As described above, the active species (compounds) which may
generate active points capable of interacting with the
photosensitive resin composition are preferably used for the
adhesion promoting layer. Any kind of energy may be applied to
generate the active points and light (UV rays, visual rays and
X-rays), plasma (oxygen, nitrogen, carbon dioxide and argon), heat
and electricity are preferably used. In addition, the surface may
be chemically decomposed by an oxidizing liquid (potassium
permanganate solution) to generate the active points.
[0222] Exemplary active species include polymerization initiators
such as a thermal polymerization initiator and a
photopolymerization initiator. The adhesion promoting layer
preferably contains the polymerization initiator in an amount of
0.1 to 50 wt % and more preferably 1.0 to 30 wt % with respect to
the total amount of the adhesion promoting layer.
[0223] The adhesion promoting layer generally has a thickness of
preferably 0.1 to 10 .mu.m and more preferably 0.2 to 5 .mu.m. At a
thickness within the above-defined range, the adhesion promoting
layer sufficiently adheres to the cured layer of the photosensitive
resin composition. The adhesion of the same level as in the case
using the adhesive is achieved although the adhesion promoting
layer is thinner than the layer using the common adhesive. As a
result, a laminate with a smaller total thickness which has a metal
film with excellent adhesion can be obtained.
[0224] The adhesion promoting layer preferably has a surface
roughness R.sub.z as measured by the 10-point mean roughness method
according to JIS B 0601 (1994) of up to 3 .mu.m and more preferably
up to 1 .mu.m in order to improve the physical properties of the
film formed by plating (metal film). When the surface roughness
R.sub.z is within the above-defined range, the adhesion promoting
layer is advantageously used to manufacture ultra-fine printed
circuit boards including, for example, a circuit pattern with a
line width of up to 25 .mu.m and a line-to-line spacing of up to 25
.mu.m.
[0225] The adhesion promoting layer is formed on the substrate by
layer forming processes such as coating, transfer and printing.
[0226] The adhesion promoting layer may be patterned as desired by
printing processes such as gravure printing, screen printing,
flexographic printing, ink-jet printing or imprinting, or by
development such as wet etching, dry etching, ablation,
(negative/positive) curing and plasticization by exposure to
light.
[0227] The adhesion promoting layer formed on the substrate may be
subjected to a curing treatment step after applying any energy
thereto. Examples of the energy applied include light, heat,
pressure and electron rays. In the embodiment under consideration,
heat or light is general and in the case of heat, heat is
preferably applied at 100 to 300.degree. C. for 5 to 120
minutes.
[0228] The conditions for thermal curing vary with the type of the
substrate material and the type of the resin composition making up
the adhesion promoting layer. The conditions also depend on the
curing temperature of these materials and thermal curing is
preferably performed at 120 to 220.degree. C. for 20 to 120
minutes.
[0229] The curing treatment step may be performed just after the
formation of the adhesion promoting layer. Alternatively, the
curing treatment step may be performed after all the other steps
following the formation of the adhesion promoting layer are
performed if a preliminary curing treatment is performed for about
5 to about 10 minutes after the formation of the adhesion promoting
layer.
[0230] The formation of the adhesion promoting layer may be
followed by surface roughening by a dry and/or wet process in order
to improve the adhesion to the cured film of the photosensitive
resin composition to be formed on its surface. Exemplary dry
surface roughening processes include mechanical polishing such as
buffing and sandblasting, and plasma etching. On the other hand,
wet surface roughening processes include treatments using chemicals
including oxidants such as permanganates, bichromates, ozone,
hydrogen peroxide/sulfuric acid and nitric acid, strong bases and
solvents that may swell resins.
[0231] As compared to the cured layer of the photosensitive resin
composition to be described later, the plating catalyst or its
precursor is less likely to deposit to the adhesion promoting
layer. Therefore, there is a large difference in the ease of
deposition of the plating catalyst or its precursor between the
adhesion promoting layer and the cured layer of the photosensitive
resin composition. In other words, the plating catalyst has
deposition selectivity. As a result, the plating catalyst mainly
deposits to the cured layer of the photosensitive resin
composition, which enables better pattern plating to be
performed.
(Film-Forming Process)
[0232] As described above, the process of forming the
photosensitive resin composition layer on the substrate is not
particularly limited. Exemplary processes include application of
the photosensitive resin composition to the substrate, and
immersion of the substrate in the photosensitive resin composition.
The application process is preferred because the layer thickness is
easily controlled.
[0233] The process of applying the photosensitive resin composition
to the substrate is not particularly limited and examples thereof
include known coating processes such as blade coating, rod coating,
squeeze coating, reverse roll coating, transfer roll coating, spin
coating, bar coating, air knife coating, gravure printing, and
spray coating.
[0234] A step of heating the photosensitive resin composition layer
may optionally be provided to remove the solvent in the
photosensitive resin composition layer after the application. The
drying temperature and time are selected as appropriate and the
photosensitive resin composition layer is preferably dried at 100
to 200.degree. C. for 10 minutes to 1 hour in terms of the
production efficiency and the handling.
[0235] The photosensitive resin composition layer obtained by this
step has an appropriately selected thickness. The thickness is
preferably from 0.1 to 10 .mu.m and more preferably from 0.2 to 5
.mu.m in terms of the application to electronic components such as
printed circuit boards.
[Exposure Step]
[0236] The exposure step is a step in which the photosensitive
resin composition layer obtained in the application step is exposed
in a pattern shape to form a cured layer. The exposure treatment
causes the crosslinking reaction between the resins to take place
in the photosensitive resin composition layer and the covalent bond
with the substrate to be formed to obtain the cured film.
[0237] The cured layer of the photosensitive resin composition is
preferably formed on the substrate by exposure to light using a
general means called surface graft polymerization. Graft
polymerization is a process in which active species are applied
onto a polymer compound chain to further polymerize another monomer
which initiates polymerization under the action of the active
species to thereby synthesize a graft polymer.
[0238] Known processes described in literatures may be used for the
surface graft polymerization that may be applied to the invention.
For example, surface graft polymerization processes including
photografting polymerization and plasma irradiation graft
polymerization are described in Shinkobunshi Jikkengaku (New
Polymer Experiments) (Vol. 10, Ed. by the Society of Polymer
Science, Japan, Kyoritsu Shuppan Co., Ltd., 1994, p. 135). Further,
graft polymerization using radiations such as .gamma.-rays and
electron beams is described in Kyuchaku Gijutsu Binran (Handbook of
Adsorption Technology) (pp. 203 and 695, supervised by Takeuchi,
NTS Co., February 1999).
[0239] Photografting polymerization is performed by processes
specifically described in JP 63-92658 A, JP 10-296895 A and JP
11-119413 A.
[0240] The other process than the foregoing surface graft
polymerization process that may be applied upon the formation of
the cured layer of the photosensitive resin composition is a
process which involves applying a reactive functional group such as
trialkoxysilyl group, isocyanate group, amino group, hydroxyl group
or carboxyl group to the end of a polymer compound chain and
bonding by a coupling reaction between the reactive functional
group and a functional group present at the surface of the
substrate.
[0241] Of these processes, in terms of increasing the amount of
graft polymer formed, photografting polymerization and particularly
UV-photografting polymerization are preferably used to form the
cured layer of the photosensitive resin composition in which the
specific polymerizable polymer is chemically bonded to the
substrate.
[0242] For patterning, exposure means using a mask is usually used
but scanning exposure using various lasers may also be used.
[0243] The exposure light source is appropriately selected and
examples thereof include UV lamp, mercury lamp, metal halide lamp,
xenon lamp, chemical lamp, and carbon arc lamp. Examples of the
radiation include electron rays, X-rays, ion beams and far infrared
rays, and g-line rays, i-line rays, deep UV rays, and high-density
energy beams (laser beams) may also be used.
[0244] Scanning exposure using an infrared laser, high-intensity
flash exposure using a xenon discharge lamp and performed via a
mask, and exposure using an infrared lamp are particularly
preferred.
[0245] The exposure time is selected as appropriate for the type of
the photosensitive resin composition used and is preferably from 5
seconds to 30 minutes in terms of the workability.
[0246] An exposure power of preferably 10 to 5,000 mJ/cm.sup.2 and
more preferably 50 to 3,000 J/cm.sup.2 is applied to facilitate the
progress of the graft reaction with the substrate.
[0247] The cured layer obtained by exposure and curing of the
photosensitive resin composition layer has no surface roughness due
to uneven application and has a very flat and smooth surface. Even
the cured layer having such a flat and smooth surface forms a
strong and irreversible interaction for coordinate bonding with
palladium as the plating catalyst based on the function of the
interactive group and therefore can also achieve good adhesion to
the metal film formed by plating which is performed using the
plating catalyst adsorbed to the cured layer as the starting
point.
[Development Step]
[0248] The development step is a step in which part of the
photosensitive resin composition layer unexposed in the exposure
step is removed, that is, the uncured area of the photosensitive
resin composition layer is removed by a developer or the like. The
uncured area is removed by development to form a patterned cured
layer.
[0249] The development process is not particularly limited as long
as the uncured area of the photosensitive resin composition layer
can be removed, and an optimal process is selected as appropriate
for the photosensitive resin composition used. An example thereof
includes a process using a highly alkaline solution at a pH of 13.0
to 13.8 as the developer. In the case of development using a highly
alkaline developer, exemplary processes include a process in which
the substrate having an uncured area of the photosensitive resin
composition layer as obtained by the exposure step is immersed in
the solution, and a process in which the developer is applied onto
the substrate, and the immersion process is preferred. In the case
of the immersion process, the immersion time is preferably from
about 1 minute to about 30 minutes in terms of the productivity and
workability.
[0250] Another process involves using a solvent in which the
photosensitive resin composition is soluble as the developer and
immersing the substrate in the solvent.
[Catalyst Applying Step]
[0251] The catalyst applying step is a step in which the cured
layer obtained in the development step is contacted with the
foregoing plating catalyst liquid to apply the plating catalyst or
its precursor derived from the palladium compound to the cured
layer. As a result of this step, the plating catalyst liquid
permeates the cured layer and the palladium or palladium ion which
serves as the nucleus in the plating treatment is applied
(adsorbed) to the cured layer.
[0252] In this step, the same plating catalyst liquid as in the
catalyst applying step in the above-described plating method is
used and the same method as above is performed. Therefore, the
description of this step is omitted.
[Plating Step]
[0253] The plating step is a step in which the cured layer to which
the plating catalyst or its precursor was applied in the catalyst
applying step is plated to form a film (metal film). In other
words, the laminate having the metal film can be obtained by
further plating the substrate having the cured layer to which the
plating catalyst was applied. In the case of obtaining the
patterned metal film, a metal film may be formed on the whole
surface of the substrate and partially etched, or the cured layer
may be preliminarily formed in a pattern shape before being
plated.
[0254] In this step, electroless plating or electroplating is
performed as in the plating step in the foregoing plating method.
Electroless plating and electroplating are performed as described
above and their description is omitted.
[0255] A substrate having a metal film (laminate) can be obtained
by these steps. More specifically, the laminate obtained has the
substrate, the cured layer of the photosensitive resin composition
formed on the substrate, and the metal film formed on the cured
layer. The substrate used may be of a laminated structure including
the substrate and the adhesion promoting layer formed thereon. A
metal film-containing laminate having metal layers formed on both
surfaces thereof can be obtained by subjecting the surfaces of the
substrate to these steps.
[0256] The resulting metal film-containing laminate has a cured
layer which is formed on the surface of the substrate and which has
good flatness and a metal layer which also has high adhesion
strength, and can be therefore used in various applications such as
electromagnetic wave protecting films, coating films, two-layer CCL
materials and electric wiring materials and in particular
advantageously used in applications which must ensure RF
transmission because of improved flatness of the interface between
the metal film and the cured layer.
[0257] In a preferred embodiment of the metal film-containing
laminate of the invention, the metal film is preferably formed by
plating on a substrate (or a cured layer of the photosensitive
resin composition if any) having a surface roughness of up to 500
nm (more preferably up to 100 nm and most preferably 0). The
strength of adhesion between the substrate and the metal pattern is
preferably at least 0.2 kN/m (and more preferably at least 0.5
kN/m).
[0258] The substrate was cut vertically to its surface and the
cross sectional surface was observed by SEM to measure the
arithmetic mean roughness R.sub.a of the substrate according to JIS
B0633-2001.
[0259] The adhesion is determined by a method which involves
adhering a copper sheet with a thickness of 0.1 mm to the surface
of the film formed by plating (metal pattern) with an epoxy
adhesive Araldite (Ciba-Geigy Ltd.), drying the adhesive at
140.degree. C. for 4 hours and conducting a 90-degree peel test
according to JIS C 6481, or a method which involves directly
peeling off the end of the film itself formed by plating to conduct
a 90-degree peel test according to JIS C 6481.
[0260] According to the method for producing the metal
film-containing laminate of the invention, a high-definition
pattern to which the plating catalyst is selectively deposited with
high efficiency is formed and the laminate obtained may have a
high-definition metal film pattern having good adhesion to the
substrate.
[0261] The thus obtained laminate having the metal film is useful
to manufacture flexible printed circuit boards used in various
applications such as semiconductor chips, various electrical
circuit boards, flexible printed circuits (FPC), chips on film
(COF), tape automated bonding (TAB), antennas, multilayer circuit
boards and mother boards.
EXAMPLES
[0262] The present invention is described below more specifically
by way of examples. However, the present invention should not be
construed as being limited to the following examples. Unless
otherwise specified, the weight ratio is expressed by percentage or
parts by weight.
(Preparation of Plating Catalyst Liquid)
[0263] Any of the water-soluble combustible liquids, palladium
acetate (Wako Pure Chemical Industries, Ltd.) and nitric acid (Wako
Pure Chemical Industries, Ltd.) were added to water in
predetermined amounts and the mixture was stirred at 26.degree. C.
for 1 week to achieve saturated dissolution thereby preparing
plating catalyst liquids in Examples 1 to 18 as shown in Table
1.
[0264] Diethylene glycol diethyl ether (Wako Pure Chemical
Industries, Ltd.), diethylene glycol dimethyl ether (Wako Pure
Chemical Industries, Ltd.), and triethylene glycol monomethyl ether
(Wako Pure Chemical Industries, Ltd.) were used for the
water-soluble combustible liquid. Diethylene glycol diethyl ether
and diethylene glycol dimethyl ether correspond to water-soluble
organic solvents having no hydroxyl group.
TABLE-US-00002 TABLE 1 Type Palla- of Solvent Water Acid dium
Example solvent content content content acetate Example 1 Tri- 39
60.75 -- 0.25 ethyl- wt % wt % wt % Example 2 ene 39 55.75
HNO.sub.3 5 wt % 0.25 glycol wt % wt % wt % Example 3 mono- 39
50.75 HNO.sub.3 10 wt % 0.25 methyl wt % wt % wt % Example 4 ether
39 45.75 HNO.sub.3 15 wt % 0.25 wt % wt % wt % Example 5 39 40.75
HNO.sub.3 20 wt % 0.25 wt % wt % wt % Example 6 39 35.75 HNO.sub.3
25 wt % 0.25 wt % wt % wt % Example 7 Di- 39 60.75 -- 0.25 ethyl-
wt % wt % wt % Example 8 ene 39 55.75 HNO.sub.3 5 wt % 0.25 glycol
wt % wt % wt % Example 9 dim- 39 50.75 HNO.sub.3 10 wt % 0.25 ethyl
wt % wt % wt % Example 10 ether 39 45.75 HNO.sub.3 15 wt % 0.25 wt
% wt % wt % Example 11 39 40.75 HNO.sub.3 20 wt % 0.25 wt % wt % wt
% Example 12 39 35.75 HNO.sub.3 25 wt % 0.25 wt % wt % wt % Example
13 Di- 39 60.75 -- 0.25 ethyl- wt % wt % wt % Example 14 ene 39
55.75 HNO.sub.3 5 wt % 0.25 glycol wt % wt % wt % Example 15
diethyl 39 50.75 HNO.sub.3 10 wt % 0.25 ether wt % wt % wt %
Example 16 39 45.75 HNO.sub.3 15 wt % 0.25 wt % wt % wt % Example
17 39 40.75 HNO.sub.3 20 wt % 0.25 wt % wt % wt % Example 18 39
35.75 HNO.sub.3 25 wt % 0.25 wt % wt % wt %
[0265] The plating catalyst liquids prepared in Examples 1 to 18
were examined for the catalyst solubility and catalyst stability.
The results of the respective catalyst liquids are shown in Table
2.
[0266] The catalyst solubility in Table 2 was rated "good" when
palladium acetate substantially dissolved on day 3 to obtain a
transparent solution as a result of visual check on the mixture
that was stirred at 26.degree. C. to prepare the plating catalyst
liquid. The catalyst solubility was rated "fair" when palladium
acetate partially dissolved in a period of more than 3 days but
within 1 week, and "poor" when palladium acetate did not dissolve
at all in a period exceeding 1 week.
[0267] The catalyst stability was rated "poor" when the solution at
25.degree. C. changed into black color within 1 day, "fair" when
the solution changed in color in a period of more than 1 day but
within 3 days, and "good" when the solution did not change in color
in a period exceeding 1 week. It seems that the solution changed
into black color due to the modification of the dissolved palladium
catalyst.
[0268] The flash point of each of the plating catalyst liquids
prepared in Examples 1 to 18 was measured by the Tag closed cup
method according to JIS-K2265. The results obtained are shown in
Table 2. The flash point of "80.degree. C.<" in Table 2 means
that the flash point is above 80.degree. C.
TABLE-US-00003 TABLE 2 Type of plating catalyst liquid Catalyst
solubility Catalyst stability Flash point Example 1 Fair Fair
80.degree. C.< Example 2 Fair Fair 80.degree. C.< Example 3
Good Fair 80.degree. C.< Example 4 Good Fair 80.degree. C.<
Example 5 Good Fair 80.degree. C.< Example 6 Good Fair
80.degree. C.< Example 7 Fair Good 77.7.degree. C. Example 8
Fair Good 77.7.degree. C. Example 9 Good Good 77.7.degree. C.
Example 10 Good Good 77.7.degree. C. Example 11 Good Good
77.7.degree. C. Example 12 Good Good 77.7.degree. C. Example 13
Fair Good 78.6.degree. C. Example 14 Fair Good 78.6.degree. C.
Example 15 Good Good 78.6.degree. C. Example 16 Good Good
78.6.degree. C. Example 17 Good Good 78.6.degree. C. Example 18
Good Good 78.6.degree. C.
[0269] Table 2 confirmed that the respective catalyst liquids show
good catalyst solubility and good catalyst stability. In
particular, the nitric acid-containing plating catalyst liquids (in
Examples 3 to 6, 9 to 12 and 15 to 18) showed excellent catalyst
solubility. The water-soluble organic solvents containing no
hydroxyl group (in Examples 7 to 18) showed excellent catalyst
stability.
[0270] The respective plating catalyst liquids shown in Table 1
showed a flash point of 40.degree. C. or higher.
[Preparation of Laminate Having Metal Film]
[Preparation of Substrate]
[0271] A glass epoxy substrate having an interlayer dielectric film
GX-13 (ABF available from Ajinomoto Co., Inc.) laminated thereon
was prepared. The interlayer dielectric film had a thickness of 40
.mu.m and a surface roughness (R.sub.z) of 0.6 .mu.m.
(Formation of Adhesion Promoting Layer 1)
[0272] A mixture solution containing 11.9 parts by weight of JER806
(bisphenol F epoxy resin available from Japan Epoxy Resins Co.,
Ltd.), 4.7 parts by weight of LA7052 (curing agent PHENOLITE
available from Dainippon Ink and Chemicals, Inc.), 21.7 parts by
weight of YP50-35EK (phenoxy resin available from Tohto Kasei Co.,
Ltd.), 61.6 parts by weight of cyclohexanone and 0.1 part by weight
of 2-ethyl-4-methylimidazole (curing accelerator) was filtered
through a filter cloth with a mesh size of 200 to prepare a coating
liquid.
[0273] The coating liquid was applied onto the interlayer
dielectric film by spin coating and then dried at 170.degree. C.
for 60 minutes for curing to obtain Substrate A1 having Adhesion
promoting layer 1 formed therein. The cured film (intermediate
layer) had a thickness of 0.5 .mu.m. The Substrate Al had a surface
roughness (R.sub.a) of 0.12 .mu.m.
[Cured Layer of Photosensitive Resin Composition]
(Synthesis of Polymer A Having Polymerizable Group and Interactive
Group]
[0274] First of all, Polymer A having a polymerizable group and an
interactive group was synthesized as described below. To a
three-neck flask with a volume of 500 mL were added 20 mL of
ethylene glycol diacetate, 7.43 g of hydroxyethyl acrylate and
32.08 g of cyanoethyl acrylate, and the mixture was heated to
80.degree. C. To the mixture was added dropwise a mixture solution
containing 0.737 g of V-601 and 20 mL of ethylene glycol diacetate
over 4 hours. After the dropwise addition, the mixture was reacted
for 3 hours.
[0275] To the reaction solution were added 0.32 g of
di-tert-butylhydroquinone, 1.04 g of U-600 (Nitto Kasei Co., Ltd.),
21.87 g of Karenz AOI (Showa Denko K.K.) and 22 g of ethylene
glycol diacetate and the mixture was reacted at 55.degree. C. for 6
hours. Then, to the reaction solution was added 4.1 g of methanol
and the reaction was allowed to proceed for another 1.5 hours.
After the end of the reaction, the solid was collected by
reprecipitation with water to obtain the Polymer A which was a
specific polymerizable polymer having nitrile group as the
interactive group. The ratio between the polymerizable
group-containing recurring unit and the nitrile group-containing
recurring unit (molar ratio) was 22:78. The molecular weight (Mw)
in terms of polystyrene was 82,000 (Mw/Mn=3.4).
(Preparation of Coating Solution)
[0276] The Polymer A (10 parts by weight) and acetonitrile (90
parts by weight) were mixed with stirring to prepare a coating
solution with a solids content of 10 wt %.
(Film-Forming Step and Exposure Step: Curing of Photosensitive
Resin Composition Layer)
[0277] The thus prepared coating solution was applied to the resin
layer of the Substrate A1 to a thickness of 1 .mu.m by spin coating
and dried at 80.degree. C. for 30 minutes. Then, a UV exposing
machine (model: UVF-502S, lamp: UXM-501MD) available from San-Ei
Electric Co., Ltd. was used to expose the insulating resin layer of
the Substrate A1 in a pattern with a line width of 12.5 .mu.m and a
line-to-line spacing of 12.5 .mu.m by 660-second irradiation via a
mask including a light transmission part made of quartz and a mask
part (non-exposed part) to which chromium was vapor-deposited. The
irradiation power as measured with an accumulated UV meter UIT 150
and a light receiving sensor UVD-5254 (Ushio Inc.) was 1.5
mW/cm.sup.2. A patterned cured layer made of the Polymer A was thus
formed on the insulating resin layer of the Substrate A1. The
amount of accumulated exposure was 500 mJ/cm.sup.2.
[0278] The same amount of exposure was applied to prepare another
cured layer of the Polymer A by exposing the whole surface without
using a mask.
[0279] Thereafter, the substrate having the cured layer formed
thereon was immersed in stirred acetonitrile for 5 minutes and then
washed with distilled water to thereby obtain Substrate A2 having a
patterned cured layer and Substrate A3 having a cured layer formed
on its whole surface.
(Measurement of Physical Properties of Cured Layer)
[0280] The patterned cured layer on the Substrate A2 and the cured
layer on the whole surface of the Substrate A3 were determined for
the physical properties according the above-described measurement
method. The results of both the layers were as described below.
[0281] Saturated water absorption at 25.degree. C. and 50% RH: 1.2
wt % [0282] Saturated water absorption at 25.degree. C. and 95% RH:
3.4 wt %
(Catalyst Applying Step)
[0283] The Substrate A2 having the patterned cured layer and the
Substrate A3 having the cured layer on the whole surface thereof
were immersed for 5 minutes in the plating catalyst liquids
prepared in Examples 1 to 18 and were then washed with water. The
catalyst was applied to the cured layers and in the case of using
the plating catalyst prepared in Example 17, the amount of catalyst
applied (palladium deposited) to the Substrates A2 and A3 was 30
mg/m.sup.2.
(Plating Step: Electroless Plating)
[0284] A Thru-Cup PGT (C. Uyemura & Co., Ltd.) and the
electroless plating bath of the composition indicated below were
used for the Substrate A2 having the patterned cured layer to which
the plating catalyst was applied, to thereby perform electroless
plating at an electroless plating temperature of 26.degree. C. for
30 minutes. A copper film with a thickness of 0.5 .mu.m was
obtained by electroless plating in each sample.
[0285] The materials used for the electroless plating solution were
as follows:
TABLE-US-00004 Distilled water 79.2 wt % PGT-A 9.0 wt % PGT-B 6.0
wt % PGT-C 3.5 wt % Formalin (formaldehyde 2.3 wt % solution from
Wako Pure Chemical Industries, Ltd.)
[0286] The metal pattern obtained using the Substrate A2 having the
patterned cured layer was observed by an optical microscope (color
3D laser scanning microscope VK-9700 (Keyence Corporation) and it
was confirmed that a copper pattern with a line width of 13 .mu.m
and a line-to-line spacing of 12 .mu.m was formed without
defects.
(Evaluation of Surface Roughness)
[0287] A cross-sectional image of the interface between the cured
layer and the metal film (film formed by plating) was taken by SEM
at a magnification of 10,000.times. and the image was used to
measure the arithmetic mean roughness R.sub.a (.mu.m) of the
interface according to JIS B0633-2001. The results are shown in
Table 3 below.
(Evaluation of Adhesion)
[0288] The Substrate A3 which has the cured layer formed on the
whole surface thereof and which was obtained not by pattern
exposure using a mask but by exposure of the whole surface was used
to prepare samples for evaluating the adhesion. The Substrate A3
and the plating catalyst liquids in Examples 1 to 18 were used to
repeat the same method as above till the electroless plating.
[0289] Subsequently, the copper film formed by electroless plating
was used as the power supply layer to perform electroplating at 3
A/dm.sup.2 for 20 minutes in the electroplating bath of the
composition indicated below. A copper film with a thickness of 12
.mu.m was obtained by electroplating in each sample.
[0290] Composition of electroplating bath
TABLE-US-00005 Copper sulfate 38 g Sulfuric acid 95 g Hydrochloric
acid 1 mL Copper Gleam PCM (Meltex Inc.) 3 mL Water 500 g
[0291] The resulting copper-plated substrate was heated at
170.degree. C. for 1 hour.
[0292] The 90.degree. peel strength of the film obtained by plating
was determined with a tensile tester RTM-100 (A & D Co., Ltd.)
by applying a tensile strength of 10 mm/min to a portion with a
width of 5 mm. The results of the respective samples are shown in
Table 3.
(Evaluation of Removability of Metal Residues by Etching)
[0293] The Substrate A3 which has the cured layer formed on the
whole surface thereof and which was obtained not by pattern
exposure using a mask but by exposure of the whole surface was used
to prepare samples for evaluating the removability of metal
residues. The Substrate A3 and the plating catalyst liquids in
Examples 1 to 18 were used to repeat the same method as above till
the electroless plating. Thereafter, a comb-like pattern described
in JPCA BU-01 2007 was formed by a known semi-additive process.
[0294] In the process, the electroplating resist was developed and
peeled off. Then, flash etching was performed for 30 seconds with
an etching solution of sulfuric acid/hydrogen peroxide to remove
copper deposited by electroless plating, thereby obtaining a
circuit board. Then, the DC insulation resistance between the pads
of the comb-like structure was measured by a resistance meter
R8340A (ADC Corporation). The resistance value obtained with the
plating catalyst liquid in Example 1 was
3.0.times.10.sup.11.OMEGA., which was a good value. Also in cases
where the other plating catalyst liquids in Examples 2 to 18 were
used, good resistance values of about 3.0.times.10.sup.11.OMEGA.
were obtained.
[0295] On the other hand, a solution of palladium nitrate (0.05 wt
%) in acetone was used as the plating catalyst liquid to prepare a
circuit board by the same method as above. The resistance value
obtained was 2.0.times.10.sup.3.OMEGA.. From a practical point of
view, the DC insulation resistance value is preferably at least
10.sup.10.OMEGA. and the use of the circuit board is limited at a
DC insulation resistance value of less than 10.sup.4.OMEGA.. It was
confirmed that the circuit board obtained using the plating
catalyst liquid of the invention showed good insulation resistance
as described above.
TABLE-US-00006 TABLE 3 Surface Ad- Plating Plating Patterned rough-
hesion catalyst deposition plating Storage ness strength Example
liquid used properties properties stability Ra (.mu.m) (kN/m) 1
Example 1 Good Good Fair 0.03 0.7 2 Example 2 Good Good Fair 0.03
0.7 3 Example 3 Good Good Fair 0.03 0.7 4 Example 4 Good Good Fair
0.03 0.7 5 Example 5 Good Good Fair 0.03 0.7 6 Example 6 Good Good
Fair 0.03 0.7 7 Example 7 Good Good Fair 0.03 0.7 8 Example 8 Good
Good Good 0.03 0.7 9 Example 9 Good Good Good 0.03 0.7 10 Example
10 Good Good Good 0.03 0.7 11 Example 11 Good Good Good 0.03 0.7 12
Example 12 Good Good Good 0.03 0.7 13 Example 13 Good Good Fair
0.03 0.7 14 Example 14 Good Good Good 0.03 0.7 15 Example 15 Good
Good Good 0.03 0.7 16 Example 16 Good Good Good 0.03 0.7 17 Example
17 Good Good Good 0.03 0.7 18 Example 18 Good Good Good 0.03
0.7
[0296] Table 3 shows the plating deposition properties, which were
rated "good" when metal deposits were uniformly formed on the whole
surface within 30 minutes by plating under the conditions described
in Examples, "fair" when metal deposits were uniformly formed as
above in a period of more than 30 minutes but up to 1 hour, and
"poor" when no uniform film was formed by plating even in a period
exceeding 1 hour.
[0297] The patterned plating properties were rated "good" when no
deposition was seen in the non-patterned area (area where no
patterned cured film was formed) on the Substrate A2 after 2-hour
electroless plating, "fair" when no deposition was seen after
30-minute electroless plating but deposition was seen after 2-hour
electroless plating, and "poor" when deposition was seen after
30-minute electroless plating.
[0298] The storage stability was rated "good" when the film formed
by performing the same plating step as above after 1-month storage
of the plating catalyst liquids in Examples 1 to 18 at 25.degree.
C. had no change in the criteria for evaluating the plating
deposition properties and the patterned plating properties, "fair"
when one of the plating deposition properties and the patterned
plating properties deteriorated, and "poor" when both of the
plating deposition properties and the patterned plating properties
deteriorated.
[0299] From a practical point of view, no sample should be rated
"poor" in the foregoing items.
[0300] The results in Table 3 confirmed that the various plating
catalyst liquids had good plating deposition properties, good
patterned plating properties and good storage stability.
Particularly Examples 7 to 18 in which a water-soluble organic
solvent having no primary or secondary hydroxyl group was used
showed excellent storage stability.
[0301] Based on the good patterned plating properties, it was
confirmed that the plating catalyst was hardly applied to the
non-patterned area where no cured layer was formed. In other words,
it was shown that the plating catalyst liquid of the invention has
good selectivity and controllability in the application of the
plating catalyst to the plating target. It was also shown that,
when used in the semi-additive process, the plating catalyst of the
invention has a high interconnect resistance and can be
advantageously used in this process.
[0302] In the various plating catalyst liquids, the surface
roughness R.sub.a of the interface between the cured layer and the
metal film (film formed by plating) was also small and the adhesion
strength of the metal film was also good.
* * * * *