Note: Descriptions are shown in the official language in which they were submitted.
U 10,909/]0?952
BRIGEIT ~IC~EL-IRO~ ALLOY ELECTROPLATING BATH AND PROCESS
-
sackground of the Invention
A variety of aqueous electroplating baths and
processes are known in the art and are in widespread
commercial use for electrodepositing a nickel-iron alloy
on electrically conductive substrates. Such nickel-
iron alloy deposits possess excellent corrosion resist-
ance and are particularly useful for providing decora-
tive finishes on corrosion susceptible substrates over
which a subsequent electrodeposit of chromium is applied.
It is extremely important that such nickel-iron decora-
tive deposits are characterized by their high-leveling
properties, e~ceptional brightness and good ductility
and tha~ these beneficial characteristics are ~niform
over the entire electrodeposit.
Typical of known nickel-iron electroplating ~ath
compositions and processes are those described in U.S.
Patents Nos. 3,354,059; 3,795,591; 3,806,429; 3,812,566;
3,878,067; 3,974,044; 3,994,694; 4,002,543; 4,089,754;
4,101,387; 4,134,802 and 4,179,343. While certain of
the nickel~iron plating bath compositions and processes
as described in the aforementioned United States Patents
have provided satisfactory electrodeposits for use in
decorative applications, a continuing problem associated
with such and other nickel-iron plating baths is their
,.. .
susceptibility or sensitivity to contaminants and oryanic
degradation products formed during prolonged use of such
baths detracting from the character and properties of the
electrodeposit. This problem is particularly pronounced
in electroplating ba-ths designed to e]ectrodeposit alloys
containing high percentages of iron, such as for eY.ample,
alloys containing above about 35% iron and operating at
a pH above about 3.4~ The progressive contamination of
such electroplating baths with greases, oils and organic
degradation products of the organic bath additives
ernployed, have been -found to cause a progressive dete-
rioration of the quality of the elec-trodeposit and to
greatly restrict the permissible bath operating para-
meters requiring relatively stringent control to main-
tain high quality electrodeposits. The progressive
deterioration of the bath is typically evidenced by
electrodeposits which contain white, blotchy or black
areas that form in the intermediate and low current
density areas of the conductive substrate being plated.
Additionally, adverse physical properties of the
electrodeposit are also evidenced, including high
stress, poor ductility and inadequate adhesion in some
instances.
In accordance with the present invention, an
improved bath composition and process is provided which
overcomes the detrimen-tal effects of ba-th contarnina-tion
dllrirlg operation, which permits operation at a higher
pH level
to achieve excellent brightness and leveling, ~hlch
permits moxe la-titude in the parameters of bath control,
and which facilitates the at-tainment of the desired high
quality nickel-iron alloy deposit on a consistent basis.
The invention further contemplates the use of a particular
replenishing agent for conventional nickel-iron baths
which when employed in controlled amounts is effective
to achieve the aforementioned benefits. Additionally,
the invention also contemplates a process for rejuvena-
ting conventional nickel-iron electroplating baths
which have been rendered inefficient or ineffective to
achieve the desired high quality deposits due to the
accumulation of contaminants therein by the controlled
addition of a rejuvenating agent effective to restore
the electroplating bath to its original operating
efficiency.
Summary of the Invention
The benefits and advantages of the present inven-
tion in accordance with the composition aspects thereof
are achieved by an aqueous acidic bath of the type suit-
able for electrodepositing a bright, high-leveling nickel-
iron alloy deposit on a conductive substrate containing
nickel ions, iron ions, an iron solubilizing agent
present in an amount to maintain the desired concentra-
tion of iron ions in solution, a buffering agent, a
primary brightening agent, preferably in combination with
one or more secondary brightening agents of the types
~3~3
known in the art present in an amount sufficient to
produce a bright, leveled nickel-iron deposit, hydrogen
ions to provide a pH within a range of about 2.6 to about
4.5 and a bath soluble addition agent present in an amount
of at least about 2 milligrams per liter (mg/11 of the
structural formula: -
~
[HC---C- (CH ) -1CH) -SO ] X
Wherein^
R is H or Cl to C4 alkyl
n is an integer from 0 to 4,
m is an integer from 0 to 1, and
X is H, NH4, or a bath compatible metal,
as well as mixtures thereof.
A particularly preferred additive agent corres-
ponding to the foregoing structural formula is propargyl
sulfonic acid and the alkali metal and ammonium salts thereof
as well as mixtures thereof. The additive agent is generally
employed in amounts up to about 800 mg/l with amounts of
about 5 to 80 mg/l being preferred.
In accordance with the process aspects of the
present invention, a bright, decorative, high-leveling
nic]cel-iron electrodeposit is produced on a conductive
substrate by immersing the substrate while cathodically
charged in an electroplating bath of the aforementioned
type controlled at a temperature of from about 105 to
180F fox a period of time to effect the electro-
deposition of the nickel-iron alloy until a desired
-
~3~3
thickness is ob-tained. The electrodeposition of the
nickel-iron alloy can be achieved over a broad current
density range such as from about 5 to about 100 amperes
per square foot (ASF). The present invention further
contemplates the process of replenishing a nickel-iron
bath by periodic and/or continuous addition of the
addi-tive agent to maintain the bath at optimum operating
efficiency as ~ell as the proeess of rejuvenating a
contaminated, ineffieient bath by the addition of the
rejuvenating agent to restore the bath to its optimum
operating eondition.
Additional advantages and benefits of the present
invention will beeome apparent upon a reading of the
description of the preferred embodiments taken in eon-
junction with the speclfie examples provided.
Deseription of the Preferred Embodiments
The present invention is particularly applicable
for the electrodeposition of deeorative niekel-iron alloy
deposits on electrieally eonduetive substrates whieh
can be utilized as a base for the subsequent eleetro-
deposition of ehromium in order to achieve the desired
decorative and/or corrosion resistant properties. While
the present invention is primarily applicable for the
electrodeposition of niekel-iron alloys on metallic
substrates, it is also eontemplated that the invention
ean be applied to plastie substrates which have been
~3~33~3
subjected to a suitable pretreatment in accordance with
well-known -techniques to achieve an electrically con-
ductive coating thereover such as a nickel or copper
layer rendering the pl.astic substrate rece~tive to the
nickel-iron alloy electroplating operation. Typical of
such plastic materials which can be elec-troplated are
ABS, polyolefin, polyvinyl chloride, and phenol-formal-
dehyde polymers~
In accordance with the composition aspects, the
aqueous electroplating bath contains as essential
constituents, nickel ions, iron ions, and iron solu-
bilizing agent present i.n an amount to maintain the
desired concentration of iron ions in solution, a
buffering agent, a primary carrier brightener, preferably
in combination with one or more secondary brightening agents
to produce a bright, high-leveling nickel-iron alloy deposit,
hydrogen ions to provide a pH of from about 2.6 to about
4.5, and preferably 3.2 to about 3.8, and a bath soluble
acetylenic additive agent present in an amount of at least
about 2 mg/l of the structural formula:
[HC-=C-lcH2)n~(cllI)m~S3] X
Wherein:
R is H or C1 to C4 alkyl
n is an integer from O to 4,
m is an integer from O to 1, and
X is H, NH4, or a bath cornpatible metal,
as well as mixtures thereof.
Additive agents corresponding to the foregoing
structural formula include 1 butyne - 3 - sulfonic acid,
1 - pentyne - 5 - sulfonic acid, propargyl sulfonic acid
and the alkali metal and ammonium salts thereof. Of
these, propargyl sulfonic acid and its bath compatible
salts comprise -the preferred additive agen-t. The
additive agent or mixtures thereof is usually employed
in amounts of about 2 to about 300 mg/1 with amounts of
about 5 to about 80 mg/l being preferred. When the
preferred propargyl sulfonic acid compound is used, it
is usually employed in amounts of about 2 to about 200
mg/l, with amounts of about 5 to 40 mg/l being preferred.
The addition of the organic additive agent of
the present invention enables the electrodeposition of
nickel-iron alloys of relatively high iron content, e.g.
about 35% and higher employing a bath operating pH in
the upper range at which improved brightness and
leveling of the deposit is attained. The additive
agent further reduces the sensitivity of the bath to
organic contaminants such as oils, greases, and organic
degradation products of the organic additives present in
the bath enabling continued operation without imposiny
stringent control of the bath operating parameters to
avoid blotchy or non-uniform deposits. The present in~
vention further contempla-tes the replenishment and
rejuvenation of contaminated baths which have lost their
effectiveness
3~2~
and capacity to produce high quality nickel-iron alloy
deposits by the addition of controlled effective amounts
of the additive agent whereby proper bath operation is
restored.
In accordance with the composition aspects of the
present invention, the nickel and iron ions are intro-
duced into the bath employing bath soluble and compati-
ble nickel and iron compounds. Preferably, inorganic
nickel salts are employed such as nickel sulfate,
nickel chloride, and the like as well as other nickel
materials such as nickel sulfamate and the like. When
nickel sulfate or sulfamate salts are used they are
conventionally employed in amounts ranging from 40 up
to about 300 g/l (calculated as nickel sulfate hexa-
hydrate). Nickel chloride can also be used and is
normally employed in an amount ranging from about 40
to about 250 g/l. The chloride or halide ions intro-
duced provide for satisfactory conductivity of the
bath and also provide satisfactory corrosion properties
of the soluble anodes.
The iron compounds preferably comprise inorganic
ferrous salts such as ferrous sulfate, ferrous chloride,
and the like. Such ferrous salts are usually employed
in amounts ranging from about 2 up to about 60 g/l.
Additionally, other bath soluble compatible iron salts
can be employed such as soluble ferrous fluoborate,
sulfamate, and the like.
23
The concentration of nickel and iron ions in
the bath is usually controlled -to provide a weiyht
ratio of nickel to iron ranging from ahout 5:1 up to
about 50:1. The concentration of nlckel lons in -the
bath is at least about 10 g/l while the concentration
of the iron ions ls at least about 0;2 g/l with the
specific arnount present being controlled to provide
the appropriate weight ratio as hereinabove set
forth.
In order to malntain the ferrous and ferric
ions ln solutlon an iron solubilizing agent is employed
in an amount to maintain the desired concentration thereof
in the bath in a form available for electrodeposition
on the substrate. The solubilizing agent maintains
the iron ions in solution by a complexing function and/
or a reducing function of ferric to ferrous ions to
avoid precipitation of ferric hydroxide. The iron
solubilizing agent employed may comprise any of those
heretofore used in the art and typically comprise
hydro~y substi-tuted lower aliphatic carboxylic acids
having from 2 to 11 carbon atoms, from 1 to 6 hydroxyl
groups and from 1 to 3 carboxyl groups such as ascorbic
acid, isoascorbic acid, citric acid, malic acid)
glutaric acid, gluconic acid, muconic acid, gluco-
heptonic acid, glycollic acid, tartaric acid and the
li~e as well as the water soluble and bath compatible
salts thereof such as ammonlum, alkali metal, as well
as nickel and iron salts thereof.
The iron solubilizing agent is usually employed
in amounts of about 5 up to about 100 g/l wi-th amounts
of about 10 to about 30 g/l being preferred. Usuall~,
concentrations of the iron solubilizing agent above
about 50 g/l are unnecessary and in some instances
are undesirable due to the formation of organic degra-
dation products over prolonged operating periods of the
bathO Such higher concentrations are also undesirable
from an economic standpoint.
The ratio of the iron solubilizing agent relative
to the iron concentration in the bath is preferably
within the range from about 1:1 up to about 20:1. At
ratios below 1:1, the iron consti-tuent may precipitate
out while at ratios above about 20:1 excessive concen-
tra-tions of the solubilizing agent may be present
resulting in the disadvantages and potential problems
hereinabove set forth~
A further essential constituent of the bath is
a buffering agent such as boric acid, acetic acid and
the like as well as the alkali metal, ammonium nickel and
iron salts thereof and other bath soluble and compatible
salts as well as mixtures thereof. The buffering agent
is usually employed in an amount of about 20 up to about
--10--
~3~
60 g/l wi-th concentrations of about 40 to about 50 g/l
being preferredO Particularly satisfactory results are
obtained employing boric acid and the bath soluble salts
thereof~
T~e bath further contains as an essential con-
stituent, a con-trolled amount of a primary or so-cal]ed
carrier brightener preferably in further cornbination with
secondary brighteners to attain the exceptional brighteness
and high-leveling of the nickel-iron deposit. The primary
brighteners are usually employed in amounts ranging from
about 0.5 to about 20 g/l with amounts of about 2 to about
8 g/l being preferred. The secondary brighteners, when used,
are usually employed in amounts of about 0.25 mg/l up to
about 1 g/1 with amounts of about 10 to about 100 mg/l being
preferred. The primary and secondary brighteners, when an
acid is involved, can be introduced into the bath in the form
of the acid itself or as a salt having bath soluble cations
such as the alkali metal ions including ammonium~
The primary brighteners suitable for use include
those as described in U.S. Patent No. 3,974/044. Such
prirnary brighteners as described in the aforementioned
patent comprise sulfo-oxygen compounds of sulfur-bearing
compounds as further described in "Modern Electroplating"
published by John Wiley and Sons, second edition, page 272
Included among such primary brighteners are saccharin,
sulfobenzaldehyde, benzenesulfonamide, sodium allyl sulfonate,
and the
like as well as mix-tures thereof. Other bath soluble
sulfo-oxygen compounds are those such as the unsaturated
aliphatic sulfonic acids, mononuclear and binuclear
aromatic sul~inic acids, mononuclear arornatic sulfon-
amides and sulfonimides, and the like. Of the foregoing,
saccharin itself or saccharin in combination with allyl
sulfonate and/or vinyl sulfonate comprise a preferred
primary brightener.
Suitable secondary brighteners include acetylenic
nickel brighteners such as the acetylenic sulfo-oxygen
compounds and acetylenic nlckel brighteners as described
in U.S. Pat. No. 3,366,667 such as the polyethers re-
sulting from the condensation reaction of acetylenic
alcohols and diols such as, propargyl aleohol, butyndiol,
and -the like and lower alkylene oxides such as,
epichlorohydrin, ethylene oxide, propylene oxide and
the like.
Additional secondary brighteners that are suitable
include nitrogen heterocyclie quaternary or betaine nickel
brighteners which are usually employed in amounts of about
1 to about 150 mg/l. Compounds o~ this type suitable
are those described in U.S. Pat. No. 2,647,866 and the
nitrogen heteroeyclic sulfonates described in U.S. Pat.
No. 3,023,151. Preferred compounds described therein
are the pyridine quaternaries or betaines or the pyridine
sulfobetaines. Suitable quaternaries that may be
~12-
employed are quinaldine propane sultone, quinaldine
dimethyl sulfate, quinaldine allyl bromide, pyridine
allyl bromide, isoquinaldine propane sultone, iso-
quinaldine ~dime-thyl sulfate, isoquinaldine allyl
bromide, and the like.
In addition, secondary brighteners further
include -the reaction product of a polyamine-type brig'nt-
ener which ~as a molecular weight ranging from 300 to
about 24,000, and an alkylating agent of the type described
in U.S. Patent No. 4,002,543. Exemplary alkalating agents
are dimethyl sulfate, chloroacetic acid, allyl bromide,
propane sultone, benzyl chloride or propargyl bromide.
me polyamine brightener may be sulfonated utilizing
as exemplary compounds sulfamic acid, chloro sulfonic
acid and the like. The ratio of polyamine to alkylating
agent or to the sulfonating agent can be varied so that
every amino group need not be alkylated or sulfonated as
the case may be.
In addition to the essential primary and optional
secondary brighteners and other bath constituents, a
further optional addition agent comprises special carrier
agents of the type described in U.S. Patent No. 3,806,429.
Such optional special additives are not required in achiev-
ing the exceptional brighteners and high leveling in accor-
dance with the present invention but their inclusion in
-13-
~3~3
the bath is usually preferred to assure bright nickel-iron
deposits over the entire surface of the substrate, even
those exposed to very low current densi-ties. Such specialty
additives comprise organic sulfide cornpounds which are
normally employed in amounts ranging from about 0.5 to
about 40 mg/l and are of the formula:-
R2
:
RlN = C-S-R
where Rl is hydrogen or a carbon atom or an organic
radical, R2 is nitrogen or a carbon atom of an organic
radical and R3 is a carbon atom of an organic radical.
Rl and R2 or R3 may be linked together through a single
organic radical.
Typically, the bath soluble organic sulfide com-
pounds can be 2-amino thiazoles and isothloureas. 2-
aminothiazole and 2-aminobenzothiazole can be reacted
with bromethane sulfonate, propane sultone, benzyl
chloride, dimethylsulfate, diethyl sulfate, methyl bro-
mide, propargyl bromide, ethylene dibromide, allyl
bromide, methyl chloro acetate, sulfophenoxyethylene
bromide, to form compounds suitable for use. Substi-
tuted 2-aminothiazoles and 2-aminobenzothiazoles, such
as 2-amino-5~hlorothiazole,2-amino-~-methylthiazole,
etc. can also be employed. Thiourea can be reacted with
propiolactone, butyrolactone, chloroacetic acid, chlo-
ropropionic acid, propane sultone, dimethyl sulfate, etc.
~3;~23
Also, phenyl thiourea, methyl thiourea, allyl thiourea
and other similar substituted thioureas can be used to
form suitable reacted compounds.
The ba-th further contains as an essential constitu-
ent, hydroyen ions to provide a pH of about 2.6 to abou-t
4.5 and preferably from about 3.2 to 3.8. The hydrogen
ions can suitably be introduced employing any of the
acids conventionally used in nickel-iron plating baths
of which sulfuric acid and hydrochloric acid are pre-
ferred.
The bath may further contain as an optional con-
stituent, a controlled amount of a reducing saccharide.
The reducing saccharide or mixture of saccharides which
càn satisfactorily be employed in accordance with the
present invention can be either a monosaccharide or a
disaccharide. The monosaccharides can be defined as
polyhydroxyaldehydes or polyhydroxyketones with at
least three aliphatically bound carbon atoms. The sim-
plest monosaccharides are glyceraldehyde (generally
termed aldose) and dihydroxyacetone (generally termed
ketose). Other suitable monosaccharides useful in the
practice of the present invention include dextrose,
sorbose, fructose, xylose, erythrose and arabinose.
Disaccharides are glucoside-type derivatives of monosac-
charides, in which one sugar forms a glucoside with an
-O~ group of some other sugar. Disaccharides suitable
for use in ~he practice of -the present invention include
--1 5--
lactose, maltose and turanose, Other disaccharides in
which the second monosaccharide may, at least momen-tarily,
possess a free carbonyl group may also be utilized.
The reducing saccharide if used, can be employed in
amounts ranging from about 1 to about 50 g/l with amounts
of about 2 to about 5 g/l being preferred. The reducing
saccharide functions as a mild reducing agent for ferric
ions present but additionally provides for exceptional
brightness and leveling of the nickel-iron electrodeposit
in combination with the tartrate-type complexing agents
and primary and secondary brighteners providing a syner-
gistic effect which is not completely understood at the
present time.
Further stabilization of the iron ions in the ferrous
state is achieved by the addition of ascorbic and/or
isoascorbic acid as well as the bath soluble and compatible
salts thereof such as the alkali metal salts. When ascorbic
and/or isoascorbic acid is employed as the sole iron solu-
bilizing agent, it can be employed in amounts up to about
100 g/l. Preferably, this stabilizing agent is employed in
combination with other iron solubilizing agents as here-
inabove set forth at concentrations ranging from about
0.5 to about 3 g/l with amounts of about 1 to 2 g/1 being
preferred.
The use of the reducing saccharide and/or stabili-
zing agent inhibits the formation of ferric ions in the
bath resul~ing from the oxidation of the ferrous salts
-16-
3i~
originally employed for bath make-up to the ferric
state during bath operation. The rate of ferric iron
ion formation is a function of the anocle area at which
o~idation occurs as well as by oxidation particularly
when air agitation of the bath is used. It is usually
preferred to control the ferric ion concentration in
the bath below about 40% of the total iron present.
In accordance with the process aspects of the present
invention, substrates to be electroplated are immersed in
the electroplating bath while cathodically charged and
are electroplated at average current densities of about 5
up to about 100 ASF, preferably 30 to about 60 ASF, for
periods of time to provide the desired plating thickness.
Usually plating thicknesses for decorative purposes
range from about 0.1 mils to about 2 mils with thicknesses
of about 0.2 to about 0.5 mils belng typical. The
operating bath is usually maintained at a temperature
ranging from 105F up to about 180F with temperatures
of about 130~F to about 140F being preferred. Plating
durations of from about 5 minutes to about 30 minutes
are usually satisfac-tory in consideration of the specific
current clensity employed and the thickness of the
plating deposits desired. Agitation of the bath during
electroplating is not necessary but is preferred employ~
ing conventional agitation means such as mechanical
agitation, air agitation, and the like.
-17-
3~3
In order to further illus-trate the electro-
platiny bath and process of the present invention, the
follo~Jing specific examples are provided. It ~7.ill be
understood that the examples are provided for illustra-
tive purposes and are not intended to be limiting of the
scope of the present invention as herein described and
as set forth in the subjoined claims.
EXAMPLE 1
A nickel-iron electroplating bath is prepared
having the following composition:
Ingredient Concentration
NiSO 6H O ~150 g/l
6H2o 75 g/l
H3BO3 50 g/l
FeSO4^7H2O 40 g/l
Sodium gluconate 20 g/l
Primary brighteners 7 g/l
Secondary brightener 20 mg/l
~- The sodium gluconate comprises the iron solu-
bilizing agent. The primary brighteners comprise a
mixture of sulfo-oxygen carrier brighteners comprising
2.5 g/l saccharin and 4.5 g/l sodium allyl sulfonate.
The secondary brightener comprises propynoxy ethylene
oxide, a reaction product of polyethylene imine (molecular
eight 1200) with sulfamic acid and 2-amino thiazoleO The
bath temperature is controlled at 140F and the pH of
the bath is adjusted to 3.5. A clean rolled steel panel
-18-
,
3~
is plated at 30 ASF for 10 minutes and the resulting
deposit was bright bu-t had a dark recess area and an
overall white blo-tchiness in the intermediate current
density areas. The concentxation of the constituents
of the bath are purposely selected to insure that an
unacceptable deposit is ob-tained ~7ith a high iron alloy
content of about ~2.5~ iron.
I~XAMPLE 2
The nickel-i.ron electroplating bath of
Example 1 is replenished to provide the same bath com-
position and in addition, 5 mg/l of propargyl sulfonate
is added. A clean rolled steel panel is plated under
the same conditions as described in Example 1 and the
resulting deposit is overall bright with excellent
recess areas and the white blotchiness is eliminated.
EXAMPLE 3
A nickel-iron plating solution which has been
in commercial operation for about one year was analyzed
and found to have the following composition of
constituents:
--19--
Ni+2 73.75 g/1
NiSO4.6H2O 187.50 g/1
NiCl2.6H2O 138.85 g/1
H3BO3 44.24 g/1
Stabilizer* 17.40 g/1
Fe+2 2.67 g/1
Fe+3 1.61 g/1
Primary Brightener 3.8%
Secondary Brightener 2.3%
pH 3.1
*Calculated as tartaric acid and comprises a mixture
originally added to the bath containing 65% tartaric acid,
15% lactose and 20% by weight isoascorbic acid.
A clean 3" X 5" polished brass panel was
plated in the above described plating solution using a
standard hull cell apparatus at 2 AMPS for 10 minutes at
140°F. The resulting deposit was overall bright and
cloud free across the entire panel.
EXAMPLE 4
The pH of a fresh sample of the nickel-iron
plating solution described in Example 3 was increased
to 3.5, the iron content increased to 5.0 g/1 and the
hull cell panel test was repeated. The resulting
deposit was bright in the high current density area
with a white smokey cloud in the intermediate current
density areas and dark and blotchy gray in the low
current density areas.
-20-
°
3~3
EXAMPLE 5
The pH of a fresh sample of the nickel-iron
plating solution of Example 3 was again increased to
3.5, the iron content increased to 5.0 g/l and 5 rng/l
of propargyl sulfonate was added to the bath. The hull
cell panel tests were repeated and the resulting deposi.t
was overall bright and cloud free across the entire
panel.
EX~ PLE 6
The pH of the solution described in Example
5 was further increased to 3.8, the brighteners and
ixon replenished and the hull cel]. panel tests were
repeated. The resulting deposit plated at 2 ~lpcfor
10 minutes was similar to the panel described in
Example 4 but the cloudiness and darkness were not as
severe, especially in the intermediate current density
areas.
EXA~lPLE 7
An addi-tional 5 mg/l of propargyl sulfonate
was added to the nickel-iron solution described in
Exa.nple 6, the brighteners and iron replenished and the
hull cell panel tests were repeated as described in
previous E~amples. The resulting deposit was now
bright and cloud free over the entire panel.
2~
E~AM?LE 3
The commercial nickel-iron plating bath
described in Example 3 was placed in a standard hull
cell equipped with air agitation. The pH of the ~ath
was increased to 3.8 and the total ir-on content was
increased to 5.0 g/l. A hull ce]l panel was plated at
2 A~IPCfor ten minutes at 145F. The resulting deposi-t
was bright in the high current density areas with severe
smokiness and grayness in the intermediate current
density areas with dark low current density areas.
EX~IPLE 9
15 mg/l of 1-butyne-3-sulfonic acid, sodium
salt, was added to the ~ath described in Fxample 8,
the brighteners and iron replenished and the hull cell
panel test was repeated. Results revealed a slight
improvement in deposit quality in that there was some
reduction in the intermediate current density cloudiness.
E~AMPLL I0
The concentration of the l-bu-tyne-3-sulfonic
acid, sodium salt, described in Example 9 was increased
to 60 mg/l, the brighteners and iron replenished and
the hull cell panel test was repea-ted. l'he resulting
deposit was overall bright and leveled over the entire
panel with only a very slight cloudiness along the
meniscus of the plated deposit.
~3~
EXAMPLE 11
The commercial plating bath specifically
described in Examples 3 an~ 8 was again used to chec~
the effectiveness of l-pentyne-5~sulfonic acid. The
initial pan~l without adding the test material was
exactly as described in Example 8. 50 mg/l of l-pentyne-
5-sulfonic acid, sodium salt was added to the bath, the
brighteners and iron replenished, and the hull cell
panel test repeated. The resulting deposit was overall
bright and leveled over the entire panel as well as
the meniscus. ---
EXAMPLE 12
The commercial plating bath specificallydescribed in Examples 3 and 8 was again used to check
the effectiveness of 3-hep^tyne-7-sulfonic acid, sodium
salt. The structure of this compound which is outside
the scope of usable compounds encompassed by the generic
structural formula hereinabove set forth is as follows:
CH -CH2-C=C-CH2-CH2-CH2 3
The initial panel before adding the test
material was exactly as described in Example 8. 50 mg/l
of the above described hep-tyne derivative was added to
the bath, the brighteners and the iron replenished, and
the hull cell panel test repeated. The resulting deposit
showed no improvement.
3~
EX~PL~ 13
The concentration of the 3-heptyne-7-sulfonic
acid, sodium salt was increased to 100 mg/l, the brlghteners
and iron replenished, and the hull cell panel test was
repeated. The resulting deposit showed no improvement~
In fact, the intermediate current density cloudiness
worsened and the recess areas appeared even darker.
While it will be apparent that the preferred
embodiments of the invention disclosed are well calcu-
lated to fulfill the objects above stated, it will be
appreciated that the invention is susceptible to
modification, variation and change without departing
from the proper scope or fair meaning of the subjoined
claims.
~2~-
