U.S. patent application number 16/646990 was filed with the patent office on 2020-07-02 for electrolytic sn or sn alloy plating solution and method for producing sn or sn alloy plated article.
The applicant listed for this patent is C. Uyemura & Co., Ltd. Invention is credited to Masato Enomoto, Toshikazu Kano, Masayuki Kiso, Akira Okada, Masanobu Tsujimoto.
Application Number | 20200208285 16/646990 |
Document ID | / |
Family ID | 65723284 |
Filed Date | 2020-07-02 |
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United States Patent
Application |
20200208285 |
Kind Code |
A1 |
Enomoto; Masato ; et
al. |
July 2, 2020 |
ELECTROLYTIC SN OR SN ALLOY PLATING SOLUTION AND METHOD FOR
PRODUCING SN OR SN ALLOY PLATED ARTICLE
Abstract
The purpose of the present invention is to provide an
electrolytic Sn or Sn alloy plating solution capable of lowering Pb
concentration. An electrolytic Sn or Sn alloy plating solution for
forming a plated article for solder bonding, at least comprising: a
sulfur-based compound; an Sn salt; one or more types of acids or
water-soluble salts thereof selected from inorganic acid, organic
acid or water-soluble salt thereof; and a surfactant, wherein the
sulfur-based compound is a thiol compound represented by following
general formula (Formula. A), a salt of the thiol compound (Formula
A), or a disulfide compound (Formula B).
Inventors: |
Enomoto; Masato; (Osaka,
JP) ; Kano; Toshikazu; (Osaka, JP) ; Okada;
Akira; (Osaka, JP) ; Tsujimoto; Masanobu;
(Osaka, JP) ; Kiso; Masayuki; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
C. Uyemura & Co., Ltd |
Osaka |
|
JP |
|
|
Family ID: |
65723284 |
Appl. No.: |
16/646990 |
Filed: |
July 26, 2018 |
PCT Filed: |
July 26, 2018 |
PCT NO: |
PCT/JP2018/028003 |
371 Date: |
March 12, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 3/32 20130101; C25D
3/60 20130101 |
International
Class: |
C25D 3/32 20060101
C25D003/32; C25D 3/60 20060101 C25D003/60 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2017 |
JP |
2017-178077 |
Claims
1. An electrolytic Sn or Sn alloy plating solution for forming a
plated article for solder bonding, at least comprising: a
sulfur-based compound; an Sn salt; one or more types of acids or
water-soluble salts thereof selected from inorganic acid, organic
acid or water-soluble salt thereof; and a surfactant, wherein the
sulfur-based compound is a thiol compound represented by following
general formula (Formula A), a salt of the thiol compound (Formula
A), or a disulfide compound (Formula B). HS--R.sub.1 Formula A:
R.sub.2--S--S--R.sub.2 Formula B: R.sub.1 is any of ##STR00027##
R.sub.2 is any of ##STR00028##
2. The electrolytic Sn or Sn alloy plating solution according to
claim 1, wherein a ratio of concentration of the sulfur-based
compound, Sn of the Sn salt, the acids or water-soluble salts
thereof, and the surfactant is 1:0.2 to 700:1 to 3000:0.01 to 1000
by weight ratio.
3. The electrolytic Sn or Sn alloy plating solution according to
claim 1, wherein the R.sub.1 is any of the general formulas (I) to
(III), the R.sub.2 is the general formula (IV) or (V), and the
Formula (A) or the Formula (B) is bonded with 2-position or
6-position of the R.sub.1 or the R.sub.2.
4. The electrolytic Sn or Sn alloy plating solution according to
claim 1, wherein the acids or water-soluble salts thereof are one
or more types of acids or salts thereof selected from sulfuric
acid, hydrochloric acid, nitric acid, phosphoric acid, sulfamic
acid, organic sulfonic acid, carboxylic acid, or salt thereof, and
also, the surfactant includes one or more types of surfactants
selected from anionic surfactant, cationic surfactant, and
non-ionic surfactant.
5. The electrolytic Sn or Sn alloy plating solution according to
claim 1, further comprising one or more types of metal salts other
than Sn salt selected from Ag salt, Cu salt, Bi salt, In salt, Au
salt, Sb salt, Zn salt, and Ni salt.
6. A method for producing an Sn or Sn alloy plated article for
producing a plated article for solder bonding, comprising: a
plating solution preparation step for preparing an electrolytic Sn
or Sn alloy plating solution; and a plating step for producing the
Sn or Sn alloy plated article using the plating solution, wherein,
in the plating solution preparation step, the electrolytic Sn or Sn
alloy plating solution is prepared by at least comprising: a
sulfur-based compound; an Sn salt; one or more types of acids or
water-soluble salts thereof selected from inorganic acid, organic
acid or water-soluble salt thereof; and a surfactant, wherein the
sulfur-based compound is a thiol compound represented by following
general formula (Formula A), a salt of the thiol compound (Formula
A), or a disulfide compound (Formula B). HS--R.sub.1 Formula A:
R.sub.2--S--S--R.sub.2 Formula B: R.sub.1 is any of ##STR00029##
R.sub.2 is any of ##STR00030##
7. The method for producing the Sn or Sn alloy plated article
according to claim 6, wherein a film of the Sn or Sn alloy plated
article is low alpha grade Sn or Sn alloy plating film (less than
0.01 counts/hr/cm.sup.2).
8. The electrolytic Sn or Sn alloy plating solution according to
claim 2, wherein the R.sub.1 is any of the general formulas (I) to
(III), the R.sub.2 is the general formula (IV) or (V), and the
Formula (A) or the Formula (B) is bonded with 2-position or
6-position of the R.sub.1 or the R.sub.2.
9. The electrolytic Sn or Sn alloy plating solution according to
claim 2, wherein the acids or water-soluble salts thereof are one
or more types of acids or salts thereof selected from sulfuric
acid, hydrochloric acid, nitric acid, phosphoric acid, sulfamic
acid, organic sulfonic acid, carboxylic acid, or salt thereof, and
also, the surfactant includes one or more types of surfactants
selected from anionic surfactant, cationic surfactant, and
non-ionic surfactant.
10. The electrolytic Sn or Sn alloy plating solution according to
claim 2, further comprising one or more types of metal salts other
than Sn salt selected from Ag salt, Cu salt, Bi salt, In salt, Au
salt, Sb salt, Zn salt, and Ni salt.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to an electrolytic Sn or Sn
alloy plating solution for forming a plated article for solder
bonding and a method for producing an Sn or Sn alloy plated article
for producing a plated article for solder bonding. The present
application claims priority based on Japanese Patent Application
No. 2017-178077 filed in Japan on Sep. 15, 2017, which is
incorporated by reference herein.
Description of Related Art
[0002] Along with higher density and higher capacity of a device,
an influence for malfunction of the device by an alpha ray
generated from soldering material used for bonding with a
semiconductor chip has become a problem which cannot be ignored. It
is known that the alpha ray is generated mainly from Pb metal
contained in the soldering material (precisely, in Sn metal) as
impurities. Therefore, in the past, it is required to lower Pb
concentration.
[0003] For example, in Patent Literature 1, it is described to
provide a plurality of solder bumps with low Pb concentration
comprised of Sn--Ag--Cu plating at a main surface of a
semiconductor chip for connecting with a mounting board. In
addition, in Patent Literature 2, it is described to bond by using
a lead-free solder for bonding structure.
[0004] Patent Literature 1: JP 2011-040606 A
[0005] Patent Literature 2: JP 2016-103530 A
SUMMARY OF THE INVENTION
[0006] However, considering a progress of a semiconductor industry,
it is considered that more miniaturization, higher density and
higher capacity of the device will progress, and it will be
necessary to cope with low alpha ray further, so Sn plating capable
of lowering Pb concentration further will be required.
[0007] Here, the purpose of the present invention is to provide an
electrolytic Sn or Sn alloy plating solution capable of lowering Pb
concentration.
[0008] An electrolytic Sn or Sn alloy plating solution relating to
one embodiment of the present invention is an electrolytic Sn or Sn
alloy plating solution for forming a plated article for solder
bonding, at least comprising: a sulfur-based compound; an Sn salt;
one or more types of acids or water-soluble salts thereof selected
from inorganic acid, organic acid or water-soluble salt thereof;
and a surfactant, wherein the sulfur-based compound is a thiol
compound represented by following general formula (Formula A), a
salt of the thiol compound (Formula A), or a disulfide compound
(Formula B).
HS-R.sub.1 Formula A:
R.sub.2--S--S--R.sub.2 Formula B:
[0009] R.sub.1 is any of
##STR00001##
[0010] R.sub.2 is any of
##STR00002##
[0011] In this way, it is possible to provide an Sn plated article
capable of lowering Pb concentration, by inhibiting eutectoid of
Pb, by functions of each component.
[0012] At this time, in one embodiment of the present invention, a
ratio of concentration of the sulfur-based compound, Sn of the Sn
salt, the acids or water-soluble salts thereof, and the surfactant
may be 1:0.2 to700:1 to 3000:0.01 to 1000 by weight ratio.
[0013] In this way, it is possible to lower Pb concentration
further, as a ratio of concentration of each component will be an
optimum ratio.
[0014] In addition, in one embodiment of the present invention, the
R.sub.1 may be any of the general formulas (I) to (III), the
R.sub.2 may be the general formula (IV) or (V), and the Formula (A)
or the Formula (B) may be bonded with 2-position or 6-position of
the R.sub.1 or the R.sub.2.
[0015] In this way, it is possible to lower Pb concentration
further, by inhibiting eutectoid of Pb.
[0016] In addition, in one embodiment of the present invention, the
acids or water-soluble salts thereof may be one or more types of
acids or salts thereof selected from sulfuric acid, hydrochloric
acid, nitric acid, phosphoric acid, sulfamic acid, organic sulfonic
acid, carboxylic acid, or salt thereof, and also, the surfactant
may include one or more types of surfactants selected from anionic
surfactant, cationic surfactant, and non-ionic surfactant.
[0017] In this way, it is possible to lower Pb concentration
further, by inhibiting eutectoid of Ph, as optimum components will
be selected.
[0018] Further, it may comprise one or more types of metal salts
other than Sn salt selected from Ag salt, Cu salt, Bi salt, In
salt, Au salt, Sb salt, Zn salt, and Ni salt.
[0019] In this way, it is possible to provide an Sn alloy plating
solution capable of lowering Pb concentration, as it will be the Sn
alloy plating solution applicable for SnAg, SnCu, SnBi, SnIn, SnAu,
SnSb, SnZn, and SnNi.
[0020] In addition, one embodiment of the present invention is a
method for producing an Sn or Sn alloy plated article for producing
a plated article for solder bonding, comprising: a plating solution
preparation step for preparing an electrolytic Sn or Sn alloy
plating solution; and a plating step for producing the Sn or Sn
alloy plated article using the plating solution, wherein, in the
plating solution preparation step, the electrolytic Sn or Sn alloy
plating solution is prepared by at least comprising: a sulfur-based
compound; an Sn salt; one or more types of acids or water-soluble
salts thereof selected from inorganic acid, organic acid or
water-soluble salt thereof; and a surfactant, wherein the
sulfur-based compound is a thiol compound represented by following
general formula (Formula A), a salt of the thiol compound (Formula
A), or a disulfide compound (Formula B).
HS--R.sub.1 Formula A:
R.sub.2--S--S--R.sub.2 Formula B:
[0021] R.sub.1 is any of
##STR00003##
[0022] R.sub.2 is any of
##STR00004##
[0023] In this way, it is possible to provide an Sn plated article
capable of lowering Ph concentration, by inhibiting eutectoid of
Pb, by functions of each component.
[0024] In addition, in one embodiment of the present invention, a
film of the Sn or Sn alloy plated article may he low alpha grade Sn
or Sn alloy plating film (less than 0.01 counts/hr/cm.sup.2).
[0025] In this way, it is possible to prevent an influence for
malfunction of the device, as it is possible to lower Pb
concentration.
[0026] As explained in the above, according to the present
invention, it is possible to provide an electrolytic Sn or Sn alloy
plating solution capable of lowering Pb concentration, by
inhibiting eutectoid of Pb, by functions of each component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a flow chart illustrating an outline of a method
for producing an Sn or Sn alloy plated article relating to one
embodiment of the present invention.
[0028] FIG. 2 illustrates a relation of an amount of alpha ray and
Pb content in Sn.
DETAILED DESCRIPTION OF THE INVENTION
[0029] Hereinafter, explaining in detail about preferred
embodiments of the present invention, with reference to the
drawings. In addition, the embodiments explained in below will not
unjustly limit the content of the present invention described in
claims, and it is not limited that all the structures explained in
the embodiments are necessary as means for solving the problem of
the present invention.
1. Electrolytic Sn or Sn alloy plating solution
[0030] 1-1. Sulfur-based compound
[0031] 1-2. Sn salt, salts other than Sn
[0032] 1-3. Acids or water-soluble salts thereof
[0033] 1-4. Surfactant
[0034] 1-5. Crystal regulator
1-6, Organic solvent
1-7. Antioxidant
[0035] 1-8. Chelating agent 2. Method for producing Sn or Sn alloy
plated article 2-1. Plating solution preparation step 2-2. Plating
step
1. Electrolytic Sn or Sn Alloy Plating Solution
[0036] An electrolytic Sn or Sn alloy plating solution relating to
one embodiment of the present invention is an electrolytic Sn or Sn
alloy plating solution for forming a plated article for solder
bonding, at least comprising: a sulfur-based compound; an Sn salt;
one or more types of acids or water-soluble salts thereof selected
from inorganic acid, organic acid or water-soluble salt thereof;
and a surfactant. And, the sulfur-based compound, the Sn salt, the
acids or water-soluble salts thereof, and the surfactant, which are
at least added, are having following characteristics. It will be
explained in detail in below.
[0037] Here, a plating solution is a solution to be used for
plating, that is, a solution in which various metals and components
are condensed in one container, a solution in which various metals
and components are divided into a plurality of containers and in
which various metals and components are condensed in each
container, a solution in which the condensed solution is adjusted
with water to prepare initial make up of electrolytic bath, and a
solution in which various metals and components are added and
adjusted to prepare initial make up of electrolytic bath.
1-1. Sulfur-Based Compound
[0038] A sulfur-based compound contained in the electrolytic Sn or
Sn alloy plating solution relating to one embodiment of the present
invention is a thiol compound represented by following general
formula (Formula A), a salt of the thiol compound (formula A), or a
disulfide compound (Formula 13).
HS--R.sub.1 Formula A:
R.sub.2--S--S--R.sub.2 Formula B:
[0039] R.sub.1 is any of
##STR00005##
[0040] R2 is any of
##STR00006##
[0041] The sulfur-based compound contained in the electrolytic Sn
or Sn alloy plating solution relating to one embodiment of the
present invention is contained as an eutectoid inhibitor of Pb,
which is a thiol compound, a salt of the thiol compound, as
indicated in the Formula A, or a disulfide compound as indicated in
the Formula B. And, R.sub.1 is any of aniline (I), pyridine (II),
or pyridine N oxide (III). In addition, R.sub.2 is any of aniline
(IV), pyridine (V), benzene (VI), butane (VII), or toluene (VIII).
In addition, as indicated in the Formula B, R.sub.2 having same
structure are bonded at left and right.
[0042] By preparing a plating solution at least comprising an Sn
salt, acids or water-soluble salts thereof, and a surfactant, as
described in below, it is possible to provide an electrolytic Sn or
Sn alloy plating solution capable of lowering Pb concentration, by
inhibiting eutectoid of Pb, by functions of each component.
[0043] In addition, there is an optimum ratio for a ratio of
concentration (g/L) of the sulfur-based compound, the Sn salt, the
acids or water-soluble salts thereof, and the surfactant contained
in the electrolytic Sn or Sn alloy plating solution relating to one
embodiment of the present invention, and the optimum ratio is
1:0.05 to 10000:0.5 to 50000:0.0005 to 10000 by weight ratio.
Preferably, 1:0.2 to 700:1 to 3000:0.01 to 1000 by weight ratio,
and more preferably, 1:0.2 to 140:2 to 400:0.01 to 200 by.sup.,
weight ratio. Further preferably, 1:4 to 16:15 to 62:0.5 to 2 by
weight ratio. For example, in a scope of further preferable ratio,
if the sulfur-based compound is 1, Sn of the Sn salt is 4 to 16,
the acids or water-soluble salts thereof is 15 to 62, and the
surfactant is 0.5 to 2 by weight ratio.
[0044] With respect to a concentration of the sulfur-based compound
by weight, when a ratio of concentration of the Sn salt, the acids
or water-soluble salts thereof, and the surfactant by weight is
outside the above range, there is a possibility that an ability to
inhibit eutectoid of Pb will be deteriorated. By adjusting to be in
the above range, a ratio of concentration of each component will be
in the optimum ratio, and eutectoid inhibiting ability will be
increased, and it will be possible to lower Pb concentration
further.
[0045] Further, a concentration of the sulfur-based compound
contained in the electrolytic Sn or Sn alloy plating solution
relating to one embodiment of the present invention is preferably
0.01 to 100 g/L. When the concentration is less than 0.01 g/L,
there is a possibility that eutectoid inhibiting ability will be
decreased. On the other hand, when the concentration is more than
100 g/L, it is not preferable in terms of cost. It is more
preferably 0.1 to 50 g/L, and further preferably 0.5 to 50 g/L.
[0046] The sulfur-based compound contained in the electrolytic Sn
or Sn alloy plating solution relating to one embodiment of the
present invention functions as the eutectoid inhibitor of Pb as
described above. It is because the sulfur-based compound added in
the plating solution shifts a deposition potential of Sn and Pb to
noble or base. (It is shifted to base side or noble side by a type
of the sulfur-based compound.) It is because a compound shifting a
deposition potential of Sn to base side tends to shift a deposition
potential of Pb also to base side, and a compound shifting a
deposition potential of Sn to noble side tends to shift a
deposition potential of Pb also to noble side. It is considered
that it is because a deposition potential of Sn will be more noble
than a deposition potential of Pb, and also, a potential difference
will be broadened more than 0.06 V at this time.
[0047] Here, in an Sn or Sn alloy plating film, Pb is contained as
impurity as described above. This is because Pb is contained in the
Sn salt added to a plating solution when preparing the Sn plating
solution. When plating, this Pb is incorporated in Sn or Sn alloy
plating. Thus, in the past, an Sn salt with low Pb concentration,
in which Ph concentration is lowered in a purification stage of the
Sn salt, is used, in order to lower an amount of Pb in the Sn or Sn
alloy plating film. However, along with more miniaturization,
higher density and higher capacity of the device as described
above, it is expected that it will be required to lower Pb
concentration further. In that case, it is difficult to lower Pb
concentration further, as more sophisticated Sn purification
technology will be necessary, and also, cost will be increased.
[0048] Here, as a result of keen examination for achieving the
purpose of the present invention, the inventors have found that the
sulfur-based compound used in one embodiment of the present
invention inhibits eutectoid of Pb, and that other components
assist to inhibit eutectoid of Pb. In other words, by at least
containing the sulfur-based compound, the Sn salt, the acids or
water-soluble salts thereof, and the surfactant, as the
electrolytic Sn or Sn alloy plating solution relating to one
embodiment of the present invention, the sulfur-based compound
inhibits eutectoid of Pb, the Sn salt, the acids or water-soluble
salts thereof, and the surfactant assist to inhibit eutectoid of
Pb, so it is possible to provide the electrolytic Sn or Sn alloy
plating solution capable of lowering Pb concentration, by
inhibiting eutectoid of Pb. Thus, by combining the sulfur-based
compound, the Sn salt, the acids or water-soluble salts thereof,
and the surfactant, it is possible to achieve the above purpose
comprehensively. It will be explained in detail in below.
[0049] In the sulfur-based compound, it is preferable that the
R.sub.1 is any of the general formulas (I) to the R.sub.2 is the
general formula (IV) or (V), and the Formula (A) or the Formula (B)
is bonded with 2-position or 6-position of the R.sub.1 or the
R.sub.2. By configuring as such molecule structure, sulfur atoms
and nitrogen atoms in the molecule structure in aqueous solution
can hold. Sn and Pb ions stronger compared to other 1, 3, 4,
5-positions. Therefore, more significant effect will be exerted
also regarding potential, and it is possible to inhibit eutectoid
of Ph further.
[0050] As thiol of the sulfur-based compound, it is not limited as
below, but concretely, benzene thiol, 1, 4-benzene dithiol, 1,
3-benzene dithiol, 1, 2-benzene dithiol, 1, 3, 5-benzene trithiol,
2-naphthalene thiol, 1, 5-naphthalene dithiol, 4-methyl
.sup.-benzene thiol, 2-methyl benzene thiol, 3-methyl benzene
thiol, 3, 5-dimethyl benzene thiol, 4-amino benzene thiol, 2,
4-dimethyl benzene thiol, 3, 4-dimethyl benzene thiol, 4-hydroxy
benzene thiol, 3-amino benzene thiol, 4-tea-butyl benzene thiol, 2,
5-dimethyl benzene thiol, 4-ethyl benzene thiol, 3-hydroxy benzene
thiol, 4-isopropyl benzene thiol, 4-methoxy benzene thiol, 2-amino
benzene thiol, 4-(dimethyl amino) benzene thiol, 3-methoxy benzene
thiol, toluene-3, 4-dithiol, 2-hydroxy benzene thiol, 2-ethyl
benzene thiol, 2-isopropyl benzene thiol, 2-methoxy benzene thiol,
3, 4-dimethoxy benzene thiol, 5-tert-buthyl-2-methyl benzene thiol,
2, 5-diamino-1, 4-benzene thiol, 3-ethoxy benzene thiol, 4-nitro
benzene thiol, 4, 4'-biphenyl dithiol, thioxylenol, 3-mercapto
benzoic acid, sodium thiosalicylate, 4-acetoamide benzene thiol,
2-mercapto pyridine, 2-mercapto pyridine N-oxide, 2-mercapto
pyridine N-sodium oxide, 2-mercapto-5-nitro pyridine, 2-mercapto
nicotinic acid, and salts of the above compounds can be cited.
[0051] In addition, as the disulfide compound of the sulfur-based
compound, it is not limited as below, but concretely, dimethyl
disulfide, dimethyl trisulfide, di-tert-butyl disulfide, diethyl
disulfide, diisopropyl disulfide, allyl methyl disulfide, diallyl
disulfide, diisobutyl disulfide, dipropyl disulfide, methyl propyl
disulfide, bis (2, 2-diethoxy ethyl) disulfide, dibutyl disulfide,
diisoamyl disulfide, bis (2-dimethyl amino ethyl) disulfide, bis
(2-hydroxy ethyl) disulfide, cystamine, diamyl disulfide,
di-tert-octyl disulfide, didecyl disulfide, allyl propyl disulfide,
tetra methyl thiuram disulfide, di-Cert-dodecyl disulfide, dicyclo
hexyl disulfide, dithio diglycolate, tetra ethyl thiuram disulfide,
2, 2'-dithio dipropionate, 3, 3'-dithio dipropionate, 4, 4'-dithio
dibutyrate, 3'-dithio dipropionate dimethyl, forrnamidine
disulfide, tetra isopropyl thiuram disulfide, dibenzyl disulfide,
methyl 2-methyl-3-furyl disulfide, tetra butyl thiuram disulfide,
bis (2-mehyl-3-furyl) disulfide, bis (phenyl acetyl) disulfide,
L-(-)-cystine, 2, 2'-dithienyl disulfide, DL-homocystine,
2-methyl-3-furyl propyl disulfide, 4, 4'-dithio dimorpholine,
difurfutyl disulfide, 3, 3'-dithio dipropionate (N-succinimidyl),
furfuryl methyl disulfide, his (2-benzamide phenyl) disulfide, N,
N'-dicarbobenzoxy-L-cystine, 2, 2'-dithio his (5-nitro pyridine),
6, 6'-dithio dinicotinate, 4, 4'-di (1, 2, 3-triazolyl) disulfide
hydrate, glutathione, 3-(2-pyridyl dithio) propionate
N-succinimidyl, 4-(2-benzothiazolyi dithio) morpholine, 2,
2'-dibenzothiazolyl disulfide, O-isobutyloyl thiamine disulfide,
aneurine disulfide, diphenyl disulfide, di-p-tolyl disulfide, bis
(4-hydroxy phenyl) disulfide, 3, 3-dithio bis (1-propane sulfonic
acid), 4, 4'-dithio dianiline, 2, 2'-dithio dianiline, bis
(3-hydroxy phenyl) disulfide, bis (6-hydroxy-2-naphthyl) disulfide,
bis (4-nitro phenyl) disulfide, bis (3-nitro phenyl) disulfide, his
(2-nitro phenyl) disulfide, his (2, 4-dinitro phenyl) disulfide, 2,
2'-dithio dibenzoate, 5, 5'-dithio bis (2-nitro benzoate), 2,
2'-dipyridyl disulfide, 4, 4'-dipyridyl disulfide, 2, 2'-dithio bis
(5-nitro pyridine), 6, 6'-dithio dinicotinate, and salts of the
above compounds can be cited. In addition, as trisulfide,
diisopropyl trisulfide or the like can be cited.
[0052] In addition, more preferably, the sulfur-based compound is
concretely 2, 2-dithio dianiline, 2-amino benzene thiol, 2,
2-dipyridyl disulfide, 2-mercapto pyridine, 2-mercapto pyridine
N-oxide. In this way, it is possible to lower Pb concentration
further by inhibiting eutectoid of Pb.
1-2. Sn Salt, Salts other than Sn
[0053] As an Sn salt contained in the electrolytic Sn or Sn alloy
plating solution relating to one embodiment of the present
invention, it is preferable to use a first Sn salt (Sn salt (II))
and a second Sn salt (Sn salt (IV)).
[0054] As the first Sn salt (Sn salt (II)), it is not limited as
below, but concretely, an organic Sn (II) sulfonate such as Sn (II)
alkane sulfonate such as Sn (II) methane sulfonate, and Sn (II)
alkanol sulfonate such as Sn (II) isethionate, Sn (II) sulfate, Sn
(II) borofluoride, Sn (II) chloride, Sn (II) bromide, Sn (II)
iodide, Sn (II) oxide, Sn (II) phosphate, Sn (II) pyrophosphate, Sn
(11) acetate, Sn (III) citrate, Sn (II) gluconate, Sn (II)
tartrate, Sn (II) lactate, Sn (II) succinate, Sn (II) sulfamate, Sn
(II) formate, Sn (II) silicofluoride, and else, can be cited.
[0055] As the second Sn salt (Sn salt (IV)), it is not limited as
below, but concretely, sodium stannate, kalium stannate, and else,
cane be cited.
[0056] Especially, the organic Sn (II) sulfonate such as Sn (II)
alkane sulfonate such as Sn (III) methane sulfonate, and Sn (II)
alkanol sulfonate such as Sn (II) isethionate, is preferable.
[0057] In addition, a concentration of the Sn salt is preferably 5
to 100 g/L. If it is less than 5 it might be a cause for occurring
a burning or a scorch as Sn concentration is too low. On the other
hand, if it is more than 100 g/L, there is a problem of an increase
in a cost, and a stability of a bath becomes unstable, so there is
a possibility for occurring precipitation. More preferably, it is
10 to 70 g/L.
[0058] Further, it is possible to use an Sn salt with low Pb
concentration, for example with Pb concentration of 1.0 ppm or
less. It will be a plating solution especially for obtaining an Sn
plated article with low Pb concentration, and it is possible to
lower Pb concentration further. Typical Sn salt and concentration
are materials and concentrations cited in the above.
[0059] In addition, it can be applied not only for Sn plating, but
also for Sn alloy plating. In other words, it is preferable that
the electrolytic Sn or Sn alloy plating solution relating to one
embodiment of the present invention further comprises one or more
types of metal salts other than Sn salt selected from Ag salt, Cu
salt, Bi salt, In salt, Au salt, Sb salt, Zn salt, Ni salt, or the
like. In this way, it will be an Sn alloy plating solution also
applicable for Sn alloy plating (SnAg, SnCu, SnBi, SnIn, SnAu,
SnSb, SnZn, SnNi, or the like), other than Sn plating, and it is
possible to provide the Sn alloy plating solution capable of
lowering Pb concentration.
1-3. Acids or Water-Soluble Salts Thereof
[0060] Acids or water-soluble salts thereof contained in the
electrolytic Sn or Sn alloy plating solution relating to one
embodiment of the present invention are one or more types of acids
or water-soluble salts thereof selected from inorganic acid,
organic acid or water-soluble salt thereof. The acids or
water-soluble salts thereof are contained for assisting inhibition
of eutectoid of Pb. It is because pH of Sn surface or a surface of
an article to be plated will be maintained constantly, and it will
be uniform surface potential, by the acids or water-soluble salts
thereof.
[0061] As the acids or water-soluble salts thereof, it is not
limited as below, but concretely, sulfuric acid, hydrochloric acid,
nitric acid, phosphoric acid, sulfamic acid, organic sulfonic acid
(alkane sulfonate such as methane sulfonate, and alkanol sulfonate
such as isethionate), carboxylic acid (aromatic carboxylic acid,
saturated aliphatic carboxylic acid, amino carboxylic acid), and
else can be cited. According to need, it is possible to use
neutralized salts of the water-soluble salts.
[0062] In addition, a concentration of the acids or water-soluble
salts thereof is preferably 50 to 500 g/L. If it is less than 50
g/L, a stability of the plating solution will be deteriorated, and
precipitates tend to occur. There is a possibility to have an
influence on Pb deposition potential. On the other hand, if it is
more than 500 g/L, cost will be increased. More preferably, it is
50 to 300 g/L, further preferably, it is 100 to 200 g/L.
1-4. Surfactant
[0063] As a surfactant contained in the electrolytic Sn or Sn alloy
plating solution relating to one embodiment of the present
invention, it is possible to use one or more types of surfactants
selected from anionic surfactant, cationic surfactant, and
non-ionic surfactant. Above all, the non-ionic surfactant is
preferable, and alkylene oxide-based surfactant is suitable. The
surfactant is contained for assisting inhibition of eutectoid of
Pb. It is because the surfactant uniforms a current density of an
Sn or Sn alloy crystal surface or an article to be plated, and
maintains uniform deposition potential at the surface.
[0064] As the alkylene oxide-based surfactant, it is not limited as
below, but concretely, polyoxyethylene alkyl ether, polyoxyethylene
alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene
alkyl amide, polyoxyethylene aliphatic ester, polyoxyethylene
multivalent alcohol ether, ethylene oxide propylene oxide block
polymer type, ethylene oxide propylene oxide random polymer type,
propylene oxide polymer type, and else, can be cited. Above all,
especially, polyoxyethylene alkyl phenyl ether is preferable.
[0065] In addition, it is preferable that the acids or
water-soluble salts thereof is one or more types of acids or salts
thereof selected from sulfuric acid, hydrochloric acid, nitric
acid, phosphoric acid, sulfamic acid, organic sulfonic acid,
carboxylic acid, or salt thereof, and also, the surfactant includes
one or more types of surfactants selected from anionic surfactant,
cationic surfactant, and non-ionic surfactant.
[0066] In addition, a concentration of the surfactant is preferably
0.05 to 100 g/L. If it is less than 0.05 g/L, there is a case that
a burning or a scorch occurs at a part to be high current density,
when it is plated at high current density in order to decrease
plating time. On the other hand, if it is more than 100 g/L, Sn
plating film will be blackened, and there is a case that a defect
such as uneven color occurs. Thus, it might have an influence on a
film of an Sn or Sn alloy plating itself. More preferably, it is
0.5 to 100 g/L.
[0067] As mentioned above, the electrolytic Sn or Sn alloy plating
solution relating to one embodiment of the present invention at
least comprises: the sulfur-based compound; the Sn salt; one or
more types of the acids or water-soluble salts thereof selected
from inorganic acid, organic acid or water-soluble salt thereof;
and the surfactant. By containing the above components in the
plating solution as described above, it will be most suitable for
inhibiting eutectoid of Pb, as the plating surface with uniform
deposition potential will be achieved by each component. In
addition, it will be difficult to achieve the above purpose, if one
constituent or component is missing.
[0068] It was explained at least about the above constituents and
components, but it is preferable that the electrolytic Sn or Sn
alloy plating solution relating to one embodiment of the present
invention further comprises following constituents and components.
It is explained in below.
1-5. Crystal Regulator
[0069] It is preferable that the electrolytic Sn or Sn alloy
plating solution relating to one embodiment of the present
invention further comprises a crystal regulator. The crystal
regulator is having an effect to smoothen a deposited film. Thus,
when an Sn or Sn alloy crystal is growing, it assists to inhibit
eutectoid of Pb by reducing a bias of local potential of crystal
surface, by further smoothening the Sn or Sn alloy crystal. In
addition, as the crystal regulator, aldehydes, ketones,
benzothiazoles, or the like, can be used.
1-6. Organic Solvent
[0070] It is preferable that the electrolytic Sn or Sn alloy
plating solution relating to one embodiment of the present
invention further comprises an organic solvent. In addition, as the
organic solvent, it is not limited as below, but concretely,
monovalent alcohols such as methanol, 2-propanol, bivalent alcohols
such as ethylene glycol, diethylene glycol, triethylene glycol, and
else, can be cited.
1-7. Antioxidant
[0071] It is preferable that the electrolytic Sn or Sn alloy
plating solution relating to one embodiment of the present
invention further comprises an antioxidant. The antioxidant is
having an effect to stabilize the solution by inhibiting oxidation
of bivalent Sn ions in a bath, and by inhibiting oxidation of other
components in the plating solution. Thus, by comprising the
antioxidant, it assists to maintain oxidation-reduction potential
of Sn more constant, so as a result, it can assist to inhibit
eutectoid of Ph. As the antioxidant, it is not limited as below,
but concretely, catechol, hydroquinone, 4-methoxy phenol, ascorbic
acid, and else, can be cited.
[0072] In addition, it is preferable that a concentration of the
antioxidant is 0.1 to 100 g/L. If the concentration is less than
0.1 g/L, an oxidation inhibiting effect may be decreased. On the
other hand, if the concentration is more than 100 g/L, the cost
tends to increase. Further preferable range is 0,1 to 10 g/L.
1-8. Chelating Agent
[0073] The electrolytic Sn or Sn alloy plating solution relating to
one embodiment of the present invention can further comprise a
chelating agent. As the chelating agent, it is not limited as
below, but concretely, oxalic acid, succinic acid, malonic acid,
glycolic acid, glconic acid, gluconolactone, glycine, ethylene
diamine acetate, pyrophosphoric acid, tripolyphosphate, and else,
can be cited.
[0074] In addition, it is preferable that a concentration of the
chelating agent is 0.1 to 200 g/L. If it is less than 0.1 g/L, a
chelating effect may be decreased. On the other hand, if it is more
than 200 g/L, the cost tends to increase. Further preferable range
is 0.1 to 100 g/L.
2. Method for Producing Sn or Sn Alloy Plated Article
[0075] As illustrated in FIG. 1, a method for producing an Sn or Sn
alloy plated article relating to one embodiment of the present
invention is a method for producing an Sn or Sn alloy plated
article for producing a plated article for solder bonding,
comprising: a plating solution preparation step S1 for preparing an
electrolytic Sn or Sn alloy plating solution; and a plating step S2
for producing the Sn or Sn alloy plated article using the plating
solution. Hereinafter, explaining in an order of steps.
2-1. Plating Solution Preparation Step
[0076] As illustrated in FIG. 1, a method for producing an Sn or Sn
alloy plated article relating to one embodiment of the present
invention comprises a plating solution preparation step S1. In the
plating solution preparation step S1, the electrolytic Sn or Sn
alloy plating solution is prepared by at least comprising: a
sulfur-based compound; an Sn salt; one or more types of acids or
water-soluble salts thereof selected from inorganic acid, organic
acid or water-soluble salt thereof; and a surfactant. And, the
sulfur-based compound is a thiol compound represented by following
general formula (Formula A), a salt of the thiol compound (Formula
A), or a disulfide compound (Formula B).
HS--R.sub.1 Formula A:
R.sub.7--S--S--R.sub.7 Formula B:
[0077] R.sub.1 is any of
##STR00007##
[0078] R.sub.2 is any of
##STR00008##
[0079] The sulfur-based compound contained in the plating solution
used in the method for producing the Sn or Sn alloy plated article
relating to one embodiment of the present invention is contained as
an eutectoid inhibitor of Pb, which is a thiol compound, a salt of
the thiol compound, as indicated in the Formula A, or a disulfide
compound as indicated in the Formula B. And, R.sub.1 is any of
aniline (I), pyridine (II), or pyridine N oxide (III). In addition,
R.sub.2 is any of aniline (IV), pyridine (V), benzene (VI), butane
(VII), or toluene (VIII).
[0080] By preparing a plating solution at least comprising the Sn
salt, the acids or water-soluble salts thereof, and the surfactant,
as described in the above, it is possible to provide the Sn or Sn
alloy plated article capable of lowering Pb concentration, by
inhibiting eutectoid of Pb, by functions of each component.
[0081] In addition, preferable compounds, a concentration, and a
ratio of concentration of the sulfur-based compound, the Sn salt,
the acids or water-soluble salts thereof, and the surfactant are as
explained in the above. In addition, as the Sn salt, it is possible
to use the Sn salt with Pb concentration of 1.0 ppm or less. It is
preferable to further comprise the crystal regulator, the organic
solvent, the antioxidant, and the chelating agent, in addition to
the sulfur-based compound, the Sn salt, the acids or water-soluble
salts thereof, and the surfactant. In order to be the Sn alloy
plating solution, as described in the above, it is preferable to
comprise one or more types of metal salts other than Sn salt
selected from Ag salt, Cu salt, Bi salt, In salt, Au salt, Sb salt,
Zn salt, Ni salt, or the like.
2-2. Plating Step
[0082] As illustrated in FIG. 1, a method for producing an Sn or Sn
alloy plated article relating to one embodiment of the present
invention comprises a plating step S2. The Sn or Sn alloy plated
article is produced using the plating solution prepared in the
plating solution preparation step S1. It is not limited
particularly, but it is preferable to perform plating with a
current density in a range of 1 to 20 A/dm.sup.2, Further
preferable range is 2 to 6 A/dm.sup.2. In addition, necessary
pretreatment and posttreatment are performed to obtain the Sn or Sn
alloy plated article.
[0083] In addition, according to the method for producing an Sn or
Sn alloy plated article, a film of the plated article is low alpha
grade Sn or Sn alloy plating film (less than 0.01
counts/hr/cm.sup.2). Here, a relation of an amount of alpha ray
(counts/hr/cm.sup.2) and Pb content in Sn is illustrated in FIG. 2.
As illustrated, an amount of alpha ray and Pb content in Sn are in
proportional relation, and when the Pb content increases, the
amount of alpha ray increases. By calculating approximation from
these data, it is amount of alpha ray
(counts/hr/cm.sup.2)=0.0048*Pb content (ppm)+0.0005. From this
approximation, Pb content corresponding to 0.01 counts/hr/cm.sup.2
is 2.0 ppm. In other words, the low alpha grade Sn or Sn alloy
plating film is having a Ph concentration of 2.0 ppm or less. In
this way, it is possible to lower Pb concentration, and it is
possible to prevent an influence for malfunction of the device.
EXAMPLES
[0084] Next, explaining in detail about an electrolytic Sn or Sn
alloy plating solution and a method for producing an Sn or Sn alloy
plated article relating to one embodiment of the present invention
by using examples. In addition, the present invention is not
limited to these examples.
Example 1
[0085] In an example 1, as an electrolytic Sn plating solution, a
sulfur-based compound, an Sn salt, an organic acid, and a
surfactant were added. As the sulfur-based compound, 5 g/L of
dibenzyl disulfide was added. As the Sn salt, 40 g/L of Sn (II)
alkane sulfonate was added as Sn (Sn.sup.2+). As the organic acid,
155.3 g/L, of organic sulfonic acid was added. As the surfactant, 5
g/L of polyoxyethylene alkyl phenyl ether was added. In addition,
as the crystal regulator, 0.15 g/L of 2-mercapto benzothiazole was
added. A solution temperature of the plating solution was
30.degree. C., and a current density was 4 A/dm.sup.2. Further, in
the example 1, a plating solution using an Sn salt with low Pb
concentration of 1.0 ppm or less was also prepared.
[0086] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 15.454 ppm, and. Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0087] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured. In addition, hereinafter, the eutectic amount of Pb when
using the Sn salt was measured using A3300 made by Hitachi
High-Tech Science Corporation, and the eutectic amount of Ph when
using the Sn salt with low Pb concentration was measured using
ICP-MS of Agilent 7700 Series made by Agilent Technologies. In
addition, the deposition potential was measured using model 2325
bipotentiostat made by BAS Inc.
Example 2
[0088] In an example 2, as the sulfur-based compound, 5 with of 4,
4'-dipyridyl disulfide was added. In addition, conditions of the Sn
salt, the organic acid, the surfactant, the crystal regulator, the
solution temperature, and the current density were same as the
example 1.
[0089] At this time, Ph concentration in raw material metal Sn of
the Sn salt was 15.454 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0090] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 3
[0091] In an example 3, as the sulfur-based compound, 5 g/L of
diphenyl disulfide was added. In addition, conditions of the Sn
salt, the organic acid, the surfactant, the crystal regulator, the
solution temperature, and the current density were same as the
example 1.
[0092] At this time, Ph concentration in raw material metal Sn of
the Sn salt was 15.454 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0093] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 4
[0094] In an example 4, as the sulfur-based compound, 5 g/L of 2,
2-dithio dianiline was added. In addition, conditions of the Sn
salt, the organic acid, the surfactant, the crystal regulator, the
solution temperature, and the current density were same as the
example 1.
[0095] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 25.885 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Ph concentration was 0.407
ppm.
[0096] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 5
[0097] In an example 5, as the sulfur-based compound, 5 g/L of
2-amino benzene thiol was added. In addition, conditions of the Sn
salt, the organic acid, the surfactant, the crystal regulator, the
solution temperature, and the current density were same as the
example 1.
[0098] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 15.454 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0099] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 6
[0100] In an example 6, as the sulfur-based compound, 5 g/L of 2,
2-dipyridyl disulfide was added. In addition, conditions of the Sn
salt, the organic acid, the surfactant, the crystal regulator, the
solution temperature, and the current density were same as the
example 1.
[0101] At this time, Ph concentration in raw material metal Sn of
the Sn salt was 26.236 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0102] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 7
[0103] In an example 7, as the sulfur-based compound, 5 of
2-mercapto pyridine was added. In addition, conditions of the Sn
salt, the organic acid, the surfactant, the crystal regulator, the
solution temperature, and the current density were same as the
example 1.
[0104] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 15.454 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Ph concentration was 0.407
ppm.
[0105] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 8
[0106] In an example 8, as the sulfur-based compound, 5 g/L of
2-mercapto pyridine N oxide Na salt was added. In addition,
conditions of the Sn salt, the organic acid, the surfactant, the
crystal regulator, the solution temperature, and the current
density were same as the example 1.
[0107] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 15.454 ppm, and. Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0108] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 9
[0109] In an example 9, as the sulfur-based compound, 5 g/L of 2,
2-dithio dianiline was added. Further, 0.5 g/L of Ag salt was
added, in order to be Sn--Ag alloy plating. In addition, conditions
of the Sn salt, the organic acid, the surfactant, the crystal
regulator, the solution temperature, and the current density were
same as the example 1.
[0110] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 40.301 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.826
ppm.
[0111] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Example 10
[0112] In an example 10, as the sulfur-based compound, 5 g/L of 2,
2-dipyridyl disulfide was added. Further, 0.5 gat of Ag salt was
added, in order to be Sn--Ag alloy plating. In addition, conditions
of the Sn salt, the organic acid, the surfactant, the crystal
regulator, the solution temperature, and the current density were
same as the example 1.
[0113] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 65.431 ppm, and. Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0114] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Comparative Example 1
[0115] In a comparative example 1, the sulfur-based compound was
not added. In addition, conditions of the Sn salt, the organic
acid, the surfactant, the crystal regulator, the solution
temperature, and the current density were same as the example
1.
[0116] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 25.807 ppm. and Ph concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0117] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Comparative Example 2
[0118] In a comparative example 2, as a sulfur-based compound, 5
g/L of 3, 6-dithia 1, 8-octanediol was added. In addition,
conditions of the Sn salt, the organic acid, the surfactant, the
crystal regulator, the solution temperature, and the current
density were same as the example 1.
[0119] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 21.584 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0120] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Ph, and a deposition potential were
measured.
Comparative Example 3
[0121] In a comparative example 3, as a sulfur-based compound, 5
gat of thiourea was added. In addition, conditions of the Sn salt,
the organic acid, the surfactant, the crystal regulator, the
solution temperature, and the current density were same as the
example 1.
[0122] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 16.794 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0123] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Comparative Example 4
[0124] In a comparative example 4, as a sulfur-based compound, 5
g/L of bis (2-amino phenyl) sulfide was added. In addition,
conditions of the Sn salt, the organic acid, the surfactant, the
crystal regulator, the solution temperature, and the current
density were same as the example 1.
[0125] At this time. Pb concentration in raw material metal Sn of
the Sn salt was 15.065 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Pb concentration was 0.407
ppm.
[0126] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Ph, a eutectic amount of Pb, and a deposition potential were
measured.
Comparative Example 5
[0127] In a comparative example 5, as a sulfur-based compound, 5
g/L of 3-amino pyridine was added. In addition, conditions of the
Sn salt, the organic acid, the surfactant, the crystal regulator,
the solution temperature, and the current density were same as the
example 1. In addition, in the comparative example 5, a plating
solution using the Sn salt with low Ph concentration was not
prepared.
[0128] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 16.068 ppm.
[0129] And, by using the above plating solution, electrolytic Sn
plating was performed, and a eutectic ratio (%) of Pb and a
eutectic amount of Pb were measured.
Comparative Example 6
[0130] In a comparative example 6, as the sulfur-based compound, 5
g/L of 2, 2-dithio dianiline was added as in the example 4, but the
organic acid and the surfactant were not added. In addition,
conditions of the Sn salt, the crystal regulator, the solution
temperature, and the current density were same as the example
1.
Comparative Example 7
[0131] In a comparative example 7, as the sulfur-based compound, 5
g/L of 2, 2-dithio dianiline was added as in the example 4, but the
surfactant was not added. In addition, conditions of the Sn salt,
the organic acid, the crystal regulator, the solution temperature,
and the current density were same as the example 1.
Comparative Example 8
[0132] In a comparative example 8, as a sulfur-based compound, 5
g/L of 3, 6-dithia 1, 8-octanediol was added. Further, 0.5 g/L of
Ag salt was added, in order to be Sn--Ag alloy plating. In
addition, conditions of the Sn salt, the organic acid, the
surfactant, the crystal regulator, the solution temperature, and
the current density were same as the example 1.
[0133] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 26.734 ppm, and Pb concentration in raw material
metal Sn of the Sn salt with low Ph concentration was 0.407
ppm.
[0134] And, by using the above two plating solutions, electrolytic
Sn plating was performed respectively, and a eutectic ratio (%) of
Pb, a eutectic amount of Pb, and a deposition potential were
measured.
Comparative Example 9
[0135] In a comparative example 9, as a sulfur-based compound, 5
g/L of thiourea was added. Further, 0.5 g/L of Ag salt was added,
in order to be Sn--Ag alloy plating. In addition, conditions of the
Sn salt, the organic acid, the surfactant, the crystal regulator,
the solution temperature, and the current density were same as the
example 1. in addition, in the comparative example 9, a plating
solution using the Sn salt with low Ph concentration was not
prepared.
[0136] At this time, Pb concentration in raw material metal Sn of
the Sn salt was 25.807 ppm.
[0137] And, by using the above plating solution, electrolytic Sn
plating was performed, and a eutectic ratio (%) of Pb, a eutectic
amount of Pb, and a deposition potential were measured.
[0138] In addition, the eutectic ratio (%) of Pb was calculated as
Pb content (ppm) in plating film/Pb content (ppm) in Sn raw
material*100. The results were illustrated in Table 1.
TABLE-US-00001 TABLE 1 Examples/ Comparative Composition examples
Compound Structure Sn plating Sn: 40 g/L Organic Sulfenic acid 155
Jg/L Polyoxyethylene alkyl phenyl ether: 5 g/L Crystal regulator
(2-mercapto benzothiazole): 0.15 g/L + compound described in right
5 g/L (However, comparative example 6 does not comprise organic
sulfonic acid and polyoxyethylene alkyl phenyl ether. Also,
comparative example 7 does not comprise polyoxyethylene alkyl
phenyl ether.) Example 1 Example 2 Example 3 Dibenzyl disulfide 4,
4'-dipyridyl disulfide Diphenyl disulfide ##STR00009## ##STR00010##
##STR00011## Example 4 2, 2-dithio dianiline ##STR00012## Example 5
2-emino benzene thiol ##STR00013## Example 6 2, 2-dipyridyl
disulfide ##STR00014## Example 7 2-mercapto pyridine ##STR00015##
Example 8 2-mercapto pyridine N oxide Na salt ##STR00016##
Comparative None example 1 Comparative example 2 3, 6-dithia 1,
8-octanediol ##STR00017## Comparative example 3 Thiourea
##STR00018## Comparative example 4 Bis (2-amino phenyl) sulfide
##STR00019## Comparative example 5 3-amino pyridine ##STR00020##
Comparative example 6 2, 2-dithio dianiline ##STR00021##
Comparative example 7 2, 2-dithio dianiline ##STR00022## Sn--Ag Sn:
40 g/L, Ag: 0.5 g/L Organic Sulfenic acid 115 mL/L Polyoxyethylene
alkyl phenyl ether: 5 g/L Crystal regulator (2-mercapto
benzothiazole): 0.15 g/L + compound described in right 5 g/L
Example 9 2, 2-dithio dianiline ##STR00023## Example 10 2,
2-dipyridyl disulfide ##STR00024## Comparative example 8 3,
6-dithia 1, B-octanediol ##STR00025## Comparative example 9
Thiourea ##STR00026## Sn Salt Pb Eutectic Examples/ concentration
amount. Pb Comparative (ppm) in Sn raw Eutectic concentration
Composition examples material metal ration (%) (ppm) in metal Sn
plating Example 1 15.454 48.7% 7.5 Sn: 40 g/L Example 2 15.454
72.1% 11.1 Organic Sulfenic acid 155 Jg/L Example 3 15.454 56.2%
8.7 Polyoxyethylene alkyl phenyl ether: Example 4 25.885 35.2% 9.1
5 g/L Example 5 15.454 21.5% 3.3 Crystal regulator Example 6 26.236
3.6% 0.9 (2-mercapto benzothiazole): 0.15 g/L Example 7 15.454
12.0% 1.9 + compound described in right Example 8 15.454 7.1% 1.1 5
g/L Comparative 26.807 330.2% 85.2 (However, comparative example 6
example 1 does not comprise organic sulfonic Comparative 21.584
316.0% 68.2 acid and polyoxyethylene alkyl example 2 phenyl
ether.Also, comparative Comparative 16.794 221.7% 37.2 example 7
does not comprise example 3 polyoxyethylene alkyl phenyl
Comparative 15.065 365.3% 53.5 ether.) example 4 Comparative 16.068
248.9% 40.8 example 5 Comparative -- -- -- example 6 Comparative --
-- -- example 7 Sn--Ag Example 9 40.301 33.0% 13.3 Sn: 40 g/L, Ag:
0.5 g/L Example 10 65.431 0.3% 0.2 Organic Sulfenic acid 115 mL/L
Comparative 26.734 270.1% 72.2 Polyoxyethylene alkyl phenyl ether:
example 8 5 g/L Comparative 25.807 183.3% 47.3 Crystal regulator
example 9 (2-mercapto benzothiazole): 0.15 g/ + compound described
in right 5 g/L Sn salt with low Pb concentration Pb Examples/
concenttration amount, Pb Comparative (ppm) in Sn raw Eutectic
concentration Composition examples material metal ration (%) (ppm)
in metal Sn plating Example 1 0.407 97.0% 0.39 Sn: 40 g/L Example 2
0.407 113.0% 0.46 Organic Sulfenic acid 155 Jg/L Example 3 0.407
103.0% 0.42 Polyoxyethylene alkyl phenyl ether: Example 4 0.407
70.0% 0.28 5 g/L Example 5 0.407 86.0% 0.35 Crystal regulator
Example 6 0.407 11.0% 0.04 (2-mercapto benzothiazole): 0.15 g/L
Example 7 0.407 15.0% 0.06 + compound described in right Example 8
0.407 8.0% 0.03 5 g/L Comparative 0.407 351% 1.43 (However,
comparative example 6 example 1 does not comprise organic sulfonic
Comparative 0.407 286.0% 1.16 acid and polyoxyethylene alkyl
example 2 phenyl ether.Also, comparative Comparative 0.407 233.0%
0.95 example 7 does not comprise example 3 polyoxyethylene alkyl
phenyl Comparative 0.407 388.0% 1.58 ether.) example 4 Comparative
example 5 Comparative -- -- -- example 6 Comparative -- -- --
example 7 Sn--Ag Example 9 0.826 90.0% 0.74 Sn: 40 g/L, Ag: 0.5 g/L
Example 10 0.407 9.0% 0.04 Organic Sulfenic acid 115 mL/L
Comparative 0.407 292.7% 1.19 Polyoxyethylene alkyl phenyl ether:
example 8 5 g/L Comparative Crystal regulator example 9 (2-mercapto
benzothiazole): 0.15 g/L + compound described in right 5 g/L
Deposition potential (V) Potential difference Examples/ (Sp - PB)
in minus: Comparative priority on Sn Composition examples Pb Sn
deposition Sn plating Example 1 -0.043 -0.111 -0.068 Sn: 40 g/L
Example 2 -0.088 -0.172 -0.084 Organic Sulfenic acid 155 Jg/L
Example 3 -0.013 -0.068 -0.075 Polyoxyethylene alkyl phenyl ether:
Example 4 -0.072 -0.135 -0.063 5 g/L Example 5 -0.061 -0.135 -0.074
Crystal regulator Example 6 -0.132 -0.236 -0.104 (2-mercapto
benzothiazole): 0.15 g/L Example 7 -0.120 -0.203 -0.077 + compound
described in right Example 8 -0.111 -0.221 -0.110 5 g/L Comparative
0.008 -0.006 -0.011 (However, comparative example 6 example 1 does
not comprise organic sulfonic Comparative 0.233 0.208 -0.025 acid
and polyoxyethylene alkyl example 2 phenyl ether.Also, comparative
Comparative 0.138 0.152 0.014 example 7 does not comprise example 3
polyoxyethylene alkyl phenyl Comparative -0.023 0.008 0.031 ether.)
example 4 Comparative example 5 Comparative -- -- -- example 6
Comparative -- -- -- example 7 Sn--Ag Example 9 -0.072 -0.135
-0.063 Sn: 40 g/L, Ag: 0.5 g/L Example 10 -0.132 -0.236 -0.104
Organic Sulfenic acid 115 mL/L Comparative 0.238 0.208 -0.025
Polyoxyethylene alkyl phenyl ether: example 8 5 g/L Comparative
0.138 0.152 0.014 Crystal regulator example 9 (2-mercapto
benzothiazole): 0.15 g/ + compound described in right 5 g/L
indicates data missing or illegible when filed
[0139] In all examples, values of eutectic ratio of Ph were lower
than which of all comparative examples, and values of eutectic
amount of Pb were lower than which of all comparative examples.
Further, in the plating solutions of all examples using the Sn salt
with low Pb concentration, values of eutectic ratio of Pb were
lower than which of all comparative examples, and values of
eutectic amount of Pb were significantly lower than which of all
comparative examples. In addition, in the examples adding the
sulfur-based compound used in the electrolytic Sn plating solution
relating to one embodiment of the present invention, the deposition
potential of Pb and Sn were shifted to noble or base, and a
deposition potential difference of Pb and Sn were broadened to 0.06
V or more, compared to the comparative examples. Thus, it was
understood that the sulfur-based compound functioned as the
eutectoid inhibitor of Pb.
[0140] In addition, in the examples 4 to 7, in which the
sulfur-based compound in which the Formula A or the Formula B is
bonded with 2-position or 6-position of the R.sub.1 or the R.sub.2,
i.e. 2, 2-dithio dianiline, 2-amino benzene thiol, 2, 2-dipyridyl
disulfide, 2-mercapto pyridine, or 2-mercapto pyridine N oxide Na
salt, is added, values of eutectic ratio of Pb were lower compared
to the examples 1 to 3, in which the Formula A or the Formula B is
bonded with other than 2-position or 6-position of the R.sub.1 or
the R.sub.2, in the plating solution of the Sn salt and in the
plating solution using the Sn salt with low Pb concentration.
[0141] In the comparative example 6 in which the organic acid and
the surfactant were not added, and in the comparative example 7 in
which the surfactant was not added, a film was not formed, so it
was not possible to measure the eutectic ratio of Pb and the Pb
concentration. As a reason that a film was not formed, it is
considered that it is because uniform surface potential was not
achieved as pH of a surface to be plated and an Sn surface were not
maintained constantly, and that it is because uniform deposition
potential was not maintained at the surface as current density of
an article to be plated and an Sn crystal surface were not uniform.
Thus, it is important to add the inorganic acid, the organic acid
or water-soluble salt thereof and the surfactant in addition to the
sulfur-based compound and the Sn salt, and it was important to
combine with the sulfur-based compound.
[0142] In addition, also in the Sn--Ag alloy plating solution, in
the examples 9 and 10, values of eutectic ratio of Ph were lower
than which of the comparative examples 8 and 9, and values of
eutectic amount of Pb were lower than which of the comparative
examples 8 and 9. Further, in the plating solutions of all the
examples using the Sn salt with low Pb concentration, values of
eutectic ratio of Pb were lower than which of all comparative
examples, and values of eutectic amount of Pb were significantly
lower than which of all comparative examples. In addition, in the
examples adding the sulfur-based compound used in the electrolytic
Sn or Sn alloy plating solution relating to one embodiment of the
present invention, the deposition potential of Pb and Sn were
shifted to noble or base, and a deposition potential difference of
Ph and Sn were broadened to 0.06 V or more, compared to the
comparative examples. Thus, it was understood that the sulfur-based
compound functioned as the eutectoid inhibitor of Pb.
[0143] By applying the electrolytic Sn or Sn alloy plating solution
and the method for producing the Sn or Sn alloy plated article
relating to one embodiment of the present invention, it was
possible to provide the electrolytic Sn or Sn alloy plating
solution capable of lowering Pb concentration, by inhibiting
eutectoid of Ph, by functions of each component.
[0144] In addition, it is explained in detail about each embodiment
and each example of the present invention as the above, but it can
be understood easily for those who skilled in the art that various
modifications can be made without practically departing from new
matters and effect of the present invention. Therefore, all such
variants should be included in the scope of the present
invention.
[0145] For example, terms described with different terms having
broader or equivalent meaning at least once in description and
drawings can be replaced with these different terms in any part of
description and drawings. In addition, operation and configuration
of the X-ray fluorescence analysis measurement method and the X-ray
fluorescence analysis measurement device are not limited to those
explained in each embodiment and each example of the present
invention, and various modifications can be made.
GLOSSARY OF DRAWING REFERENCES
[0146] S1 Plating solution preparation step [0147] S2 Plating
step
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