U.S. patent application number 16/493480 was filed with the patent office on 2020-12-31 for composition for pretreatment for electroless plating, pretreatment method for electroless plating, and electroless plating method.
This patent application is currently assigned to OKUNO CHEMICAL INDUSTRIES CO., LTD.. The applicant listed for this patent is OKUNO CHEMICAL INDUSTRIES CO., LTD.. Invention is credited to Koji Kita, Shingo Nagamine.
Application Number | 20200407854 16/493480 |
Document ID | / |
Family ID | 1000005089880 |
Filed Date | 2020-12-31 |
United States Patent
Application |
20200407854 |
Kind Code |
A1 |
Nagamine; Shingo ; et
al. |
December 31, 2020 |
COMPOSITION FOR PRETREATMENT FOR ELECTROLESS PLATING, PRETREATMENT
METHOD FOR ELECTROLESS PLATING, AND ELECTROLESS PLATING METHOD
Abstract
The present invention provides a pretreatment composition for
electroless plating, a pretreatment method, and an electroless
plating method that exhibit high plating deposition performance
without using harmful chromic acid and expensive palladium, while
reducing the number of steps. The present invention provides a
pretreatment composition for electroless plating that contains 10
mg/L or more of manganese ions and 10 mg/L or more of monovalent
silver ions.
Inventors: |
Nagamine; Shingo;
(Osaka-shi, Osaka, JP) ; Kita; Koji; (Osaka-shi,
Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OKUNO CHEMICAL INDUSTRIES CO., LTD. |
Osaka-shi, Osaka |
|
JP |
|
|
Assignee: |
OKUNO CHEMICAL INDUSTRIES CO.,
LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
1000005089880 |
Appl. No.: |
16/493480 |
Filed: |
May 23, 2018 |
PCT Filed: |
May 23, 2018 |
PCT NO: |
PCT/JP2018/019776 |
371 Date: |
September 12, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 18/30 20130101;
C23C 18/40 20130101; C23C 18/34 20130101 |
International
Class: |
C23C 18/30 20060101
C23C018/30; C23C 18/34 20060101 C23C018/34; C23C 18/40 20060101
C23C018/40 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2017 |
JP |
2017-102106 |
Claims
1-6. (canceled)
7. An electroless plating method for a resin material, the method
comprising (1) step 1: bringing the surface to be treated of the
resin material into contact with a pretreatment composition, and
(2) step 2: bringing the surface to be treated of the resin
material into contact with an electroless plating solution, wherein
the pretreatment composition contains 10 mg/L or more of manganese
ions and 10 mg/L or more of monovalent silver ions, and the
pretreatment composition has a pH of 2 or less, the method not
comprising a catalyst-adding step.
8. The electroless plating method according to claim 7, wherein the
electroless plating solution contains a reducing agent that is
catalytically active on silver.
9. The electroless plating method according to claim 7, wherein
manganese of the manganese ions has a valence of 3 or more.
10. The electroless plating method according to claim 8, wherein
manganese of the manganese ions has a valence of 3 or more.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pretreatment composition
for electroless plating, a pretreatment method for electroless
plating, and an electroless plating method.
BACKGROUND ART
[0002] Molded resin articles have been used in automobile parts for
the purpose of reducing the weight of automobiles, for example.
Resins used for molded resin articles for this purpose include, for
example, ABS resin, PC/ABS resin, PPE resin, and polyamide resin.
Such molded resin articles are plated with copper, nickel, or other
metals to add a luxurious appearance or aesthetic appeal.
Additionally, a method for forming a plating film such as one of
copper on a resin substrate has been performed in methods for
forming a conductor circuit by imparting conductivity to such a
resin substrate.
[0003] A typical method for forming a plating film on a resin
material, such as a resin substrate or a molded resin article,
includes performing etching treatment with chromic acid to roughen
the surface of the resin material, optionally followed by
neutralization and pre-dipping; adding an electroless plating
catalyst using a colloid solution containing a tin compound and a
palladium compound; performing activation treatment (accelerator
treatment) for removing tin; and sequentially performing
electroless plating and electroplating.
[0004] However, this method is harmful to the environment and the
human body because of the use of chromic acid. This method also
requires higher cost due to the use of expensive palladium for
adding a catalyst. This method also involves many steps, because
after the etching treatment step, a catalyst-adding step must be
further performed separately.
[0005] There is suggested a method for forming a plating film on a
resin material; the method includes bringing a part to be plated
into contact with an aqueous solution containing a metal activator
species to perform etching, bringing the part into contact with a
solution of reducing agent capable of reducing the metal activator
species, and bringing the part into contact with an electroless
plating solution to perform metal plating (see PTL 1).
[0006] However, there is room to research in terms of the
components of the activator species in the method according to PTL
1, and the formation of the plating film in PTL 1 is
insufficient.
[0007] Thus, there is demand for the development of a pretreatment
composition for electroless plating, a pretreatment method, and an
electroless plating method that exhibit high plating deposition
performance without using harmful chromic acid and expensive
palladium, while reducing the number of steps.
CITATION LIST
Patent Literature
[0008] Patent Literature 1: U.S. Pat. No. 4,198,799
SUMMARY OF INVENTION
Technical Problem
[0009] The present invention has been made in view of the problems
descried above. An object of the invention is to provide a
pretreatment composition for electroless plating, a pretreatment
method, and an electroless plating method that exhibit high plating
deposition performance without using harmful chromic acid and
expensive palladium, while reducing the number of steps.
Solution to Problem
[0010] The present inventors conducted extensive research to
achieve the object, and found that a pretreatment composition for
electroless plating that contains 10 mg/L or more of manganese ions
and 10 mg/L or more of monovalent silver ions, a pretreatment
method, and an electroless plating method can achieve the object.
The inventors then completed the present invention.
[0011] Specifically, the present invention relates to the following
pretreatment composition for electroless plating, pretreatment
method, and electroless plating method. [0012] 1. A pretreatment
composition for electroless plating, the composition comprising 10
mg/L or more of manganese ions and 10 mg/L or more of monovalent
silver ions. [0013] 2. The pretreatment composition for electroless
plating according to Item 1, wherein manganese of the manganese
ions has a valence of 3 or more. [0014] 3. The pretreatment
composition according to Item 1 or 2, which has a pH of 2 or less.
[0015] 4. A pretreatment method for electroless plating for a resin
material, the method comprising [0016] step 1: bringing the surface
to be treated of the resin material into contact with a
pretreatment composition, wherein the pretreatment composition
contains 10 mg/L or more of manganese ions and 10 mg/L or more of
monovalent silver ions. [0017] 5. An electroless plating method for
a resin material, the method comprising [0018] (1) step 1: bringing
the surface to be treated of the resin material into contact with a
pretreatment composition, and [0019] (2) step 2: bringing the
surface to be treated of the resin material into contact with an
electroless plating solution, wherein the pretreatment composition
contains 10 mg/L or more of manganese ions and 10 mg/L or more of
monovalent silver ions. [0020] 6. The electroless plating method
according to Item 5, wherein the electroless plating solution
contains a reducing agent that is catalytically active on
silver.
Advantageous Effects of Invention
[0021] The pretreatment composition for electroless plating
according to the present invention can exhibit high plating
deposition performance in electroless plating in the post-step
without using harmful chromic acid and expensive palladium. The
pretreatment composition for electroless plating according to the
present invention also eliminates the need for separately
performing an etching step and a catalyst-adding step, thus
reducing the number of steps for performing electroless
plating.
[0022] The pretreatment method for electroless plating according to
the present invention makes it easy to treat the surface to be
treated of a resin material, and reduces the number of pretreatment
steps, because bringing the surface to be treated of the resin
material into contact with the pretreatment composition enables the
surface to be treated to be etched, while also adding a silver
catalyst to the surface to be treated.
[0023] The electroless plating method according to the present
invention makes it easy to treat the surface to be treated of a
resin material and also reduces the number of steps for performing
electroless plating, because bringing the surface to be treated of
the resin material into contact with the pretreatment composition
in the pretreatment step enables the surface to be treated to be
etched, while also adding a silver catalyst to the surface to be
treated, thus eliminating the need for a catalyst-adding step and
an accelerator treatment step.
DESCRIPTION OF EMBODIMENTS
[0024] The following describes the present invention in more
detail.
1. Pretreatment Composition for Electroless Plating
[0025] The pretreatment composition for electroless plating
according to the present invention (simply "pretreatment
composition" below) contains 10 mg/L or more of manganese ions and
10 mg/L or more of monovalent silver ions. Because the pretreatment
composition according to the present invention contains a specific
amount of manganese ions and a specific amount of monovalent silver
ions, a reduction in etching power on the surface to be treated of
a resin material is curbed, and the addition of a catalyst becomes
sufficient.
[0026] For example, a pretreatment composition containing manganese
ions and palladium ions, due to the presence of palladium ions,
suffers a decrease in etching power of manganese ions.
Additionally, a pretreatment composition containing chromic acid
and silver ions generates a precipitate of silver chromate
(Ag.sub.2CrO.sub.4), which is an insoluble precipitate, and this
discharges silver ions out of the system, thereby resulting in
insufficient addition of a catalyst.
[0027] In contrast, the pretreatment composition according to the
present invention, due to the presence of manganese ions and
monovalent silver ions, can form a plating film excellent in
adhesion on the surface to be treated of a resin material by
bringing the surface to be treated into contact with the
pretreatment composition, and then bringing the surface to be
treated into contact with an electroless plating solution.
[0028] The pretreatment composition according to the present
invention, due to the presence of manganese ions and monovalent
silver ions, also enables both etching of the surface to be treated
of a resin substrate and addition of a catalyst simultaneously by
bringing the surface to be treated into contact with the
composition, thus making it possible to skip a catalyst-adding
step.
[0029] Moreover, the pretreatment composition according to the
present invention eliminates the need for using a palladium-tin
colloid solution as in a traditional catalyst-adding step, and also
makes it possible to skip the activation treatment (accelerator
treatment) step for removing tin.
[0030] Specifically, the pretreatment composition according to the
present invention can exhibit high plating deposition performance
in electroless plating in the post-step without using harmful
chromic acid and expensive palladium. The pretreatment composition
for electroless plating according to the present invention also
eliminates the need for separately performing an etching step and a
catalyst-adding step and the need for performing an accelerator
treatment step, thus substantially decreasing the steps for
performing electroless plating.
Manganese Ions
[0031] Manganese ions are not particularly limited as long as they
have oxidizing power. Manganese of manganese ions preferably has a
valence of 3 or more, more preferably 4 or more, and still more
preferably 7. For example, manganese ions contained in the
pretreatment composition may be in the form of metal ions alone,
such as trivalent manganese ions and quadrivalent manganese ions,
or in the form of permanganate ions, which are septivalent
manganese. Of these, from the standpoint of higher etching power,
quadrivalent manganese ions and permanganate ions are preferable,
and permanganate ions are more preferable. Manganese ions of
divalent manganese have no oxidizing power, and the use thereof
alone does not cause the surface of a resin material to be etched.
However, such manganese ions may be used in combination with
manganese ions of trivalent or higher manganese.
[0032] One kind of manganese ions may be used alone or two or more
kinds of manganese ions may be used in combination.
[0033] Manganate for adding manganese ions to the pretreatment
composition is not particularly limited, and includes manganese(II)
sulfate, manganese(III) phosphate, manganese(IV) oxide, sodium
permanganate(VII), and potassium permanganate(VII). Of these, from
the standpoint of adding manganese ions that have higher etching
power, manganese(III) phosphate, manganese(IV) oxide, sodium
permanganate(VII), and potassium permanganate(VII) are preferable;
and sodium permanganate(VII) and potassium permanganate(VII) are
more preferable.
[0034] One kind of manganate may be used alone or two or more kinds
of manganate may be used in combination.
[0035] The pretreatment composition according to the present
invention contains manganese ions in an amount of 10 mg/L or more.
An amount of manganese ions of less than 10 mg/L leads to
insufficient etching of a resin material, reducing the adhesion of
the film formed by electroless plating. The amount of manganese
ions is preferably 10 mg/L to 100 g/L, more preferably 100 mg/L to
50 g/L, still more preferably 0.2 g/L to 30 g/L, particularly
preferably 0.5 g/L to 15 g/L, and most preferably 0.5 g/L to 10
g/L. Setting the lower limit of the amount of manganese ions within
these ranges further improves the etching power of the pretreatment
composition. Setting the upper limit of the amount of manganese
ions within these ranges further reduces the generation of the
precipitate of manganese dioxide in the pretreatment composition
and further improves bath stability.
Silver Ions
[0036] The silver ions contained in the pretreatment composition
according to the present invention are monovalent silver ions. A
silver salt for adding monovalent silver ions is not particularly
limited as long as the silver salt can add monovalent silver ions
that are stable in a bath when dissolved in the pretreatment
composition, and as long as the counterions that form the silver
salt do not have an adverse effect on manganese ions. Specifically,
such silver salts include silver (I) sulfate, silver(I) nitrate,
and silver(I) oxide. Of these, from the standpoint of high
solubility and convenience in industrial application, silver(I)
nitrate is preferable. Silver (I) sulfate is also preferable
because silver(I) sulfate leads to higher deposition performance in
plating and higher resistance to decreases in adhesion of the
plating film even on resin materials formed of a resin such as an
acrylonitrile-butadiene-styrene copolymer resin (ABS resin) or a
polymer alloy of a styrene based-resin with a polycarbonate (PC)
resin, on which it is hard to form a plating deposition,.
[0037] One kind of such silver salts may be used alone or two or
more kinds of silver salts may be used in combination.
[0038] The pretreatment composition according to the present
invention contains monovalent silver ions in an amount of 10 mg/L
or more. An amount of monovalent silver ions of less than 10 mg/L
leads to insufficient deposition of electroless plating. The amount
of monovalent silver ions is preferably 10 mg/L to 20 g/L, more
preferably 50 mg/L to 15 g/L, and still more preferably 100 mg/L to
10 g/L. Setting the lower limit of the amount of monovalent silver
ions within these ranges allows a sufficient amount of a silver
catalyst to adsorb on the surface of a resin material and causes an
electroless plating film to more sufficiently deposit on the
surface. Although the amount of monovalent silver ions beyond the
upper limits described above does not have an adverse effect,
setting the upper limit as described above can reduce the amount of
the silver salt for use, thereby decreasing cost.
[0039] Silver ions for use may be monovalent silver obtained by
placing metal silver in an acidic manganese bath, and dissolving
it. The acid for forming an acidic manganese bath is not
particularly limited, and may be an inorganic acid or an organic
sulfonic acid.
[0040] The inorganic acid includes sulfuric acid, phosphoric acid,
nitric acid, hydrochloric acid, hydrofluoric acid, and boric acid.
Of these, from the standpoint of excellence in effluent treatment,
sulfuric acid is preferable.
[0041] The organic sulfonic acid includes aliphatic sulfonic acids,
such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic
acid, and pentanesulfonic acid; and aromatic sulfonic acids, such
as toluenesulfonic acid, pyridinesulfonic acid, and phenolsulfonic
acid. Of these, from the standpoint of excellent bath stability of
the pretreatment composition, aliphatic sulfonic acids are
preferable.
[0042] One kind of such acids may be used alone or two or more
kinds of acids may be used in combination.
[0043] The acid concentration of the pretreatment composition
according to the present invention is not particularly limited; for
example, the pretreatment composition has a total acid
concentration of preferably 100 to 1800 g/L, and more preferably
800 to 1700 g/L.
Other Component
[0044] The pretreatment composition according to the present
invention may contain a high-molecular compound in addition to the
manganese ions and the silver ions. The type of the high-molecular
compound is not particularly limited; from the standpoint of
facilitating plating deposition, a cationic polymer may preferably
be used. The amount of the high-molecular compound is preferably
0.01 to 100 g/L, and more preferably 0.1 to 10 g/L.
Solvent
[0045] The manganese ions, the silver ions, and optionally added
other components of the pretreatment composition according to the
present invention are preferably contained in a solvent.
[0046] The solvent is not particularly limited, and includes water,
an alcohol, and a mixture solvent of water and an alcohol.
[0047] The solvent is preferably water from the standpoint of its
excellent safety. Specifically, the pretreatment composition
according to the present invention is preferably an aqueous
solution.
[0048] The alcohol is not particularly limited, and a known
alcohol, such as ethanol, may be used.
[0049] A mixture solvent of water and an alcohol for use preferably
has a low alcohol concentration. Specifically, the alcohol
concentration is preferably about 1 to 30 mass %.
[0050] The pretreatment composition according to the present
invention is preferably acidic. Due to the acidity of the
pretreatment composition, etching treatment on a resin material is
more sufficiently performed. The pretreatment composition according
to the present invention preferably has a pH of 2 or less, and more
preferably 1 or less.
2. Pretreatment Method for Electroless Plating for Resin
Material
[0051] The pretreatment method for electroless plating for a resin
material according to the present invention includes (step 1)
bringing the surface to be treated of the resin material into
contact with the pretreatment composition, and the pretreatment
composition contains 10 mg/L or more of manganese ions and 10 mg/L
or more of monovalent silver ions.
Step 1
[0052] Step 1 is a step of bringing the surface to be treated of
the resin material into contact with the pretreatment
composition.
[0053] The pretreatment composition for use may be the pretreatment
composition for electroless plating described above.
[0054] The method for bringing the surface to be treated of a resin
material into contact with the pretreatment composition is not
particularly limited. The surface of a resin material may be
brought into contact with the pretreatment composition by a known
method. Such a method includes a method in which a resin material
is immersed in a pretreatment composition, and a method in which
the surface to be treated of a resin material is sprayed with a
pretreatment composition. Of these, from the standpoint of higher
contact efficiency, the method in which a resin material is
immersed in a pretreatment composition is preferable.
[0055] The temperature of the pretreatment composition in step 1 is
not particularly limited, and is preferably 30 to 100.degree. C.,
more preferably 40 to 90.degree. C., and still more preferably 50
to 80.degree. C. Setting the lower limit of the temperature of the
pretreatment composition within these ranges ensures more
sufficient etching of the resin material surface and addition of a
catalyst. Setting the upper limit of the temperature of the
pretreatment composition within these ranges provides film
appearance with much better decorativeness.
[0056] The contact time during which the pretreatment composition
is in contact with the surface to be treated of a resin material in
step 1 is preferably 3 to 60 minutes, more preferably 5 to 50
minutes, and still more preferably 10 to 40 minutes. Setting the
lower limit of the contact time within these ranges ensures more
sufficient etching of the resin material surface and addition of a
catalyst. Setting the upper limit of the contact time within these
ranges provides film appearance with much better
decorativeness.
[0057] The use of a chromic acid-sulfuric acid mixture, which is
related art, leads to immediate generation of a precipitate of
silver chromate (Ag.sub.2CrO.sub.4) when monovalent silver ions are
added to a bath; this makes it unable for silver to stably exist as
ions in the pretreatment composition. Thus, when a chromic
acid-sulfuric acid mixture, which is related art, is used, it is
hard to use a pretreatment composition containing silver ions,
unlike the present invention.
[0058] The resin for forming a resin material that is the object to
be treated is not particularly limited. Resin materials for use may
be a range of resin materials on which etching treatment is
performed with an acid mixture of chromic acid and sulfuric acid.
An excellent electroless plating film can be formed on such resin
materials. Examples of the resin for forming a resin material
include styrene based-resins, such as
acrylonitrile-butadiene-styrene copolymer resin (ABS resin), a
resin formed by replacing the butadiene rubber component of the ABS
resin with an acrylic rubber component (AAS resin), and a resin
formed by replacing the butadiene rubber component of the ABS resin
with an ethylene-propylene rubber component (AES resin). A polymer
alloy of such a styrene based-resin and polycarbonate (PC) resin
(e.g., a polymer alloy with a PC resin content of about 30 to 70
mass %), or the like can also be preferably used. Additionally,
usable resins include those excellent in heat resistance and
physical properties, such as polyphenylene ether resins,
polyphenylene oxide resins, polybutylene terephthalate (PBT)
resins, polyphenylene sulfide (PPS) resins, and polyamide
resins.
[0059] The resin material is not particularly limited in terms of
shape, size, etc. The pretreatment method according to the present
invention can also form a plating film excellent in decorativeness,
physical properties and the like on large-size resin materials with
a wide surface area. Such large-size resin materials include
automotive associated parts, such as radiator grilles, hubcaps,
small or medium emblems, and door handles; exterior trim items in
the electrical and electronic field; faucet fittings used in the
bathtub, sink, or basin area; and recreational-machine-associated
items, such as Japanese pinball gaming parts.
[0060] In step 1 described above, the surface to be treated of a
resin material is brought into contact with a pretreatment
composition, and the surface to be treated is treated.
[0061] The pretreatment method according to the present invention
may include degreasing treatment before step 1 in order to remove
smudges from the surface to be treated of the resin material. The
degreasing treatment is not particularly limited, and may be
performed in accordance with a known method.
[0062] The pretreatment method according to the present invention
may include, after step 1, a post-treatment that uses a
post-treatment solution containing an inorganic acid in order to
remove manganese adhered to the surface of the resin material.
[0063] The inorganic acid is not particularly limited, and examples
include hydrochloric acid, sulfuric acid, nitric acid, phosphoric
acid, hydrofluoric acid, and boric acid. Of these, from the
standpoint of excellent manganese removability, hydrochloric acid
is preferable.
[0064] One kind of such inorganic acids may be used alone or two or
more kinds of inorganic acids may be used in combination.
[0065] The amount of the inorganic acid in the post-treatment
solution is not particularly limited, and may be about 1 to 1000
g/L.
[0066] The post-treatment method is not particularly limited. For
example, a resin material that has been pretreated by the
pretreatment method may be immersed in the post-treatment solution
with a liquid temperature of about 15 to 50.degree. C. for about 1
to 10 minutes. This post-treatment can further improve the
deposition performance and appearance of the formed plating
film.
[0067] The pretreatment method for electroless plating for a resin
material described above can etch the surface to be treated of a
resin material, while also adding a silver catalyst to the surface
to be treated, and exhibits high plating deposition performance in
electroless plating in the post-step.
3. Electroless Plating Method for Resin Material
[0068] The electroless plating method for a resin material
according to the present invention includes (1) bringing the
surface to be treated of the resin material into contact with a
pretreatment composition (step 1), and (2) bringing the surface to
be treated of the resin material into contact with an electroless
plating solution (step 2), and the pretreatment composition
contains 10 mg/L or more of manganese ions and 10 mg/L or more of
monovalent silver ions.
Step 1
[0069] Step 1 in the electroless plating method for a resin
material according to the present invention is identical to the
step described as step 1 of the pretreatment method for electroless
plating for a resin material above.
Step 2
[0070] Step 2 is a step of bringing the surface to be treated of
the resin material into contact with an electroless plating
solution.
[0071] The method for bringing the surface to be treated of the
resin material into contact with an electroless plating solution is
not particularly limited. The surface to be treated of the resin
material may be brought into contact with an electroless plating
solution by a known method. From the standpoint of much higher
contact efficiency, the method is preferably one in which the
surface to be treated of a resin material is immersed in an
electroless plating solution.
[0072] The electroless plating solution is not particularly
limited, and a known autocatalytic electroless plating solution may
be used. The electroless plating solution includes electroless
nickel plating solutions, electroless copper plating solutions,
electroless cobalt plating solutions, electroless nickel-cobalt
alloy plating solutions, and electroless gold plating
solutions.
[0073] The electroless plating solution preferably contains a
reducing agent that is catalytically active on silver. The reducing
agent includes dimethylamine borane, formalin, glyoxylic acid,
tetrahydroboric acid, and hydrazine.
[0074] The conditions under which the surface to be treated of a
resin material is brought into contact with an electroless plating
solution are not particularly limited. For example, when a resin
material is immersed in an electroless plating solution, the liquid
temperature of the electroless plating solution may be about 20 to
70.degree. C., and the immersion time may be about 3 to 30
minutes.
[0075] The amount of the reducing agent in the electroless plating
solution is not particularly limited, and is preferably about 0.01
to 100 g/L, and more preferably about 0.1 to 10 g/L. Setting the
lower limit of the amount of the reducing agent within these ranges
further improves the plating deposition performance, while setting
the upper limit of the amount of the reducing agent within these
ranges further improves the stability of the electroless plating
bath.
[0076] In the electroless plating method according to the present
invention, step 2 may be repeated two or more times as necessary.
Repeating step 2 two or more times forms two or more layers of the
electroless plating film.
[0077] The electroless plating method according to the present
invention may include, before step 2, an activation treatment that
uses an activation treatment solution containing a reducing agent
and/or an organic acid in order to improve the deposition
performance in electroless plating.
[0078] The reducing agent for use in the activation treatment is
not particularly limited, and the reducing agent includes
dimethylamine borane, formalin, glyoxylic acid, tetrahydroboric
acid, hydrazine, hypophosphite, erythorbic acid, ascorbic acid,
hydroxylamine sulfate, hydrogen peroxide, and glucose. Of these,
from the standpoint of much higher plating deposition performance,
dimethylamine borane, formalin, glyoxylic acid, tetrahydroboric
acid, and hydrazine are preferable.
[0079] One kind of such reducing agents may be used alone, or two
or more kinds of reducing agents may be used in combination.
[0080] The concentration of the reducing agent in the activation
treatment solution is not particularly limited, and is preferably
0.1 to 500 g/L, more preferably about 1 to 50 g/L, and still more
preferably 2 to 25 g/L.
[0081] The organic acid for use in the activation treatment is not
particularly limited, and includes formic acid, oxalic acid,
glycolic acid, tartaric acid, citric acid, maleic acid, acetic
acid, propionic acid, malonic acid, succinic acid, lactic acid,
malic acid, gluconic acid, glycine, alanine, aspartic acid,
glutamic acid, iminodiacetic acid, nitrilotriacetic acid, and
fumaric acid. Of these, from the standpoint of much higher plating
deposition performance, formic acid, oxalic acid, glycolic acid,
tartaric acid, citric acid, and maleic acid are preferable.
[0082] One kind of such organic acids may be used alone, or two or
more kinds of organic acids may be used in combination.
[0083] The concentration of the organic acid in the activation
treatment solution is not particularly limited, and is preferably
0.1 to 500 g/L, more preferably about 1 to 50 g/L, and still more
preferably 2 to 25 g/L.
[0084] The activation treatment method is not particularly limited.
For example, a resin material that has been pretreated in step 1
described above may be immersed in an activation treatment solution
with a liquid temperature of about 15 to 50.degree. C. for about a
few seconds to 10 minutes.
[0085] The electroless plating method for a resin material
according to the present invention may further include, after step
2, an electroplating step.
[0086] The electroplating step may include optionally performing an
activation treatment with an aqueous solution, such as of an acid
or an alkali after step 2, and then immersing the resin material in
an electroplating solution to perform electroplating.
[0087] The electroplating solution is not particularly limited, and
can be suitably selected from known electroplating solutions
depending on the purpose.
[0088] The electroplating method is not particularly limited. For
example, the resin material on which an electroless plating film
has been formed in step 2 may be immersed in an activation
treatment solution with a liquid temperature of about 15 to
50.degree. C. at a current density of about 0.1 to 10 A/dm.sup.2
for about a few seconds to 10 minutes.
EXAMPLES
[0089] The following describes the present invention in more detail
with reference to Examples and Comparative Examples. However, the
present invention is not limited to these Examples.
Preparation of Electroless Plating Film
[0090] A flat plate (10 cm.times.5 cm.times.0.3 cm, surface area:
about 1 dm.sup.2) of ABS resin (manufactured by UMG ABS, tradename:
UMG ABS3001 M) was prepared as a resin material (an object to be
plated), and an electroless plating film was formed in accordance
with the following method.
[0091] First, the resin material was immersed in an alkaline
degreasing solution (manufactured by Okuno Chemical Industries Co.,
Ltd, Ace Clean A-220 bath) at 40.degree. C. for 5 minutes, and
washed with water.
[0092] Subsequently, components were added to water (a solvent) in
accordance with the formulations shown in Tables 1 and 2 to prepare
pretreatment compositions of the Examples and Comparative Examples.
The resin material after being washed with water was immersed in
the individual, prepared pretreatment compositions (immersion
temperature: 68.degree. C., and immersion time: 30 minutes).
[0093] Finally, the resin material was immersed in individual
electroless plating solutions prepared by adding components to
water (a solvent) in accordance with the formulations shown in
Tables 1 and 2 at 40.degree. C. for 10 minutes, thereby forming an
electroless plating film.
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4
Example 5 Pretreatment Manganese (II) Sulfate (g/L) 0 10 0 20 15
Composition Manganese (III) Phosphate (g/L) 0 0 8 0 2 Manganese
(IV) Oxide (g/L) 0 0 0 10 1 Sodium Permanganate (VII) (g/L) 1.5 2 0
0 1 Sulfuric Acid (g/L) 780 780 0 0 1100 Phosphoric Acid (g/L) 0
200 0 780 100 Methanesulfonic Acid (g/L) 380 200 1000 0 0 Silver
Nitrate (g/L) 3.4 0 5 0 0.02 Silver Sulfate (g/L) 0 15 10 0.09 0
Manganese Ion Content (mg/L) 580 4410 1465 13590 6840 Ag (I) Ion
Content (mg/L) 2160 10380 10095 62 13 pH <1 <1 <1 <1
<1 Electroless Nickel Sulphate Hexahydrate (g/L) 40 40 0 0 40
Plating Bath Sodium Acetate (g/L) 10 10 0 0 10 Sodium Citrate (g/L)
10 10 0 0 10 Copper Sulfate Pentahydrate (g/L) 0 0 15 15 0 Sodium
Hydroxide (g/L) 0 0 10 10 0 EDTA (g/L) 0 0 20 20 0 Dimethylamine
Borane (g/L) 4 3 0 0 3 Formaldehyde (g/L) 0 0 5 10 0 Sodium
Hypophosphite (g/L) 0 0 0 0 10
TABLE-US-00002 TABLE 2 Comparative Comparative Comparative
Comparative Comparative Comparative Comparative Example 1 Example 2
Example 3 Example 4 Example 5 Example 6 Example 7 Pretreatment
Manganese (II) Sulfate (g/L) 0 0 15 0.7 0 0 15 Composition
Manganese (III) Phosphate (g/L) 0 0 2 0.8 0 0 2 Manganese (IV)
Oxide (g/L) 0 0 0 0 0 0 0 Sodium Permanganate (VII) (g/L) 0 0.001 2
0 1.5 1.5 2 Sulfuric Acid (g/L) 0 780 1200 780 780 780 1200
Phosphoric Acid (g/L) 800 0 0 0 0 0 0 Methanesulfonic Acid (g/L) 0
100 0 0 380 380 0 Silver Nitrate (g/L) 15 0 0.01 0 0 0 0 Silver
Sulfate (g/L) 0 5 0 0.001 0 0 0.01 Palladium Sulfate (mg/L) 0 0 0 0
95 38 0 Manganese Ion Content (mg/L) 0 0.4 6590 400 580 580 6590 Ag
(I) Ion Content (mg/L) 9520 3460 6 0.7 0 0 6 Pd (II) Ion Content
(mg/L) 0 0 0 0 50 20 0 pH <1 <1 <1 <1 <1 <1 <1
Electroless Nickel Sulphate Hexahydrate (g/L) 40 40 40 0 40 40 40
Plating Bath Sodium Acetate (g/L) 10 10 10 0 10 10 10 Sodium
Citrate (g/L) 10 10 10 0 10 10 10 Copper Sulfate Pentahydrate (g/L)
0 0 0 15 0 0 0 Sodium Hydroxide (g/L) 0 0 0 10 0 0 0 EDTA (g/L) 0 0
0 20 0 0 0 Dimethylamine Borane (g/L) 3 4 3 0 4 4 3 Formaldehyde
(g/L) 0 0 0 5 0 0 0 Sodium Hypophosphite (g/L) 0 0 10 0 0 0 10
[0094] The deposit percentage and adhesion of the plating films
formed by the method described above were evaluated in accordance
with the following methods.
(1) Deposit Percentage
[0095] The percentage of the area of the electroless plating film
on the surface of the resin material was evaluated as a deposit
percentage. A full coverage of the surface of the resin material
was taken as a deposit percentage of 100%.
(2) Peel Strength Measurement
[0096] The resin material having an electroless plating film formed
thereon was immersed in a copper sulfate plating bath, and
subjected to electroplating treatment at a current density of 3
A/dm.sup.2 at a temperature of 25.degree. C. for 120 minutes to
form a copper plating film, thereby preparing a sample. The sample
was dried at 80.degree. C. for 120 minutes and allowed to stand
until being cooled to room temperature. Subsequently, a 10-mm-width
cut was made on the plating film, and the plating film was pulled
in a perpendicular direction to the surface of the resin material
with a tensile tester (manufactured by Shimadzu Corporation,
autograph AGS-J 1kN), thereby measuring peel strength. Table 3
illustrates the results.
TABLE-US-00003 TABLE 3 Deposit Percentage Peel Strength (%) (N/cm)
Example 1 100 13.1 Example 2 100 12.8 Example 3 100 10.5 Example 4
100 10.1 Example 5 100 10.9 Comparative 100 1.0 or less Example 1
Comparative 100 2.1 Example 2 Comparative 85 10.2 Example 3
Comparative 25 Unmeasurable Example 4 Comparative 100 6.5 Example 5
Comparative 80 7.1 Example 6 Comparative 95 10.2 Example 7
[0097] The results shown in Table 3 reveal that plating films
formed by immersing the resin material in the pretreatment
compositions containing 10 mg/L or more of manganese ions and 10
mg/L or more of monovalent silver ions of Examples 1 to 5 and then
immersing the resin material in an electroless plating solution
exhibit a high deposit percentage and excellent adhesion.
[0098] Additionally, plating films formed by immersing the resin
material in the pretreatment compositions of Examples 1 to 5 and
then immersing the resin material in an electroless plating
solution were confirmed to not require adding a catalyst in a
separate catalyst-adding step to enhance the deposit percentage,
because the films were fully covered with a deposit percentage of
100%. Thus, the use of the pretreatment composition for electroless
plating according to the present invention was confirmed to reduce
the adhesion of a catalyst on the surface of a jig used in forming
an electroless plating film, thereby reducing the deposition of the
plating film on the surface of the jig. This reduces the unevenness
of the electroless plating film on the surface of the resin
material because, when forming an electroless plating film using a
jig repeatedly, the plating film deposited on the surface of the
jig is exfoliated in the form of granules, and then incorporated
into the electroless plating film on the surface of the resin
material in each step.
[0099] Typically, when pretreatment is performed on a resin
material by etching treatment with chromic acid, and an electroless
plating catalyst is added using a colloid solution containing a tin
compound, a palladium compound etc., chromic acid works as catalyst
poison to reduce the adhesion of the catalyst onto the surface of a
jig, thereby reducing the deposition of the plating film on the
surface of the jig. However, when chromic acid is not used for
environmental consideration, for example, the electroless plating
film formed on the surface of the resin material becomes uneven due
to the deposition of the plating film on the jig.
[0100] In contrast, a plating film formed by immersing a resin
material in the pretreatment composition according to the present
invention and then immersing the resin material in an electroless
plating solution is fully covered with a deposit percentage of
100%; thus, it is unnecessary to separately add a catalyst in a
catalyst-adding step to increase the deposit percentage. This
reduces the adhesion of a catalyst on the surface of a jig used in
forming an electroless plating film, the deposition of the plating
film on the surface of the jig, and the unevenness of the
electroless plating film formed on the surface of the resin
material.
[0101] The use of the pretreatment composition free from manganese
ions of Comparative Example 1 or the pretreatment composition with
a septivalent manganese concentration of less than 10 mg/L of
Comparative Example 2 resulted in low adhesion of the plating
film.
[0102] The use of the pretreatment composition with a
monovalent-silver-ion concentration of less than 10 mg/L of
Comparative Example 3 or 4 resulted in a plating film with a lower
deposit percentage.
[0103] The use of the pretreatment composition containing 50 mg/L
of divalent palladium ions, instead of monovalent silver ions, of
Comparative Example 5 resulted in a plating film with lower
adhesion, although the deposit percentage of the plating film was
not decreased. The use of the pretreatment composition containing
20 mg/L of divalent palladium ions of Comparative Example 6
resulted in a plating film with a deposit percentage lower than
that of Comparative Example 5, although the adhesion of the plating
film was decreased less than that of Comparative Example 5.
[0104] Additionally, a comparison between Comparative Examples 3
and 7 reveals that the use of silver(I) sulfate as a silver salt
for adding monovalent silver ions further increases the deposit
percentage of the plating film.
* * * * *