444
A. Maizelis and B. Bairachniy
alloys, and multilayer coatings of high quality. Even though the deposition time for a
commercial copper electrowinning circuit is around 1 week, it is critically important
to control the nucleation, growth, and nature of the initial deposit [10, 11].
The nucleation and growth of copper nuclei were studied for different substrates:
Au [12–14], Pt [15], Ru [16], Pd [17], Ni [18, 19], W [20], Ta [21], RuTa seeded
substrate [22], Ti [23], TiN [24], stainless steel [10, 25], passivated chromium [26],
anodized thin-film aluminum [9], titanium oxide films [27], Si [28–30], immiscible
liquid-liquid interface [31], and various forms of carbons used as electrodes
including glassy carbon [2, 7], pencil graphite [32], graphene [33], boron-doped
diamond [3], and conductive polymers [34]. We chose nickel substrate because it
is important for the micro-component industry, in multilayer coating formation.
Moreover, nickel is used in industry as an underlayer before copper layer deposition.
Copper nucleation was studied in different electrolytes, both nonaqueous [19]
and aqueous electrolytes, such as sulfate [8, 10, 15, 25], chloride [35], perchlorate [3, 36, 37], tetrafluoroborate [38], methanesulfonate [39], as well as complex,
EDTA [40], glycinate [18], tartrate [41], pyrophosphate [9, 42, 43], and ammonia [2]. The nucleation processes in polyligand electrolytes [20, 44], which are an
active instrument to influence the coating properties [45–47], have been studied a
little.
In this chapter we analyze the process of copper nucleation and growth in
additive-free polyligand pyrophosphate-ammonia electrolyte. Pyrophosphateammonia copper-containing component was used in the development of electrolyte
for copper-nickel multilayer coating formation. Such polyligand electrolyte has
high buffer capacity, good throwing power, and the ability to deposit on an
electronegative substrate and produce coatings that simultaneously possess high
mechanical and anticorrosive properties [48, 49].
28.2 Experimental
All solutions were prepared from analytical grade chemicals and distilled water
without further treatment. Pyrophosphate-ammonia polyligand electrolyte for the
copper deposition contained 0.1 mol L −1 CuSO 4 · 5H 2 O, 0.22 mol L −1 K 4 P 2 O 7 ,
and 0.77 mol L −1 NH 3 (NH
+
4 ). The pH of solution was adjusted to 9.25 by H 2 SO 4
and KOH solutions.
Electrochemical measurements were carried out in the three-electrode cell using
a potentiostat PI-50.1. The results were transferred from analogue form to digital
by means of the two-channel voltmeter and TeleMax program for PC (100 signals
per second). Cyclic voltammograms (CVA) were obtained at a potential scan rate of
50 mV s −1 . The working electrodes were made of nickel. Before each measurement,
the electrode surface was updated by the treatment with carbide-silicone paper
(500, 1000, 2000, and 3000 grit, sequentially), cleaned by sonication in distilled
water and cathodically polarized to obtain reproducible results in the range of the
potentials corresponding to the surface oxide reduction process. The Pt electrode
A. Maizelis and B. Bairachniy
alloys, and multilayer coatings of high quality. Even though the deposition time for a
commercial copper electrowinning circuit is around 1 week, it is critically important
to control the nucleation, growth, and nature of the initial deposit [10, 11].
The nucleation and growth of copper nuclei were studied for different substrates:
Au [12–14], Pt [15], Ru [16], Pd [17], Ni [18, 19], W [20], Ta [21], RuTa seeded
substrate [22], Ti [23], TiN [24], stainless steel [10, 25], passivated chromium [26],
anodized thin-film aluminum [9], titanium oxide films [27], Si [28–30], immiscible
liquid-liquid interface [31], and various forms of carbons used as electrodes
including glassy carbon [2, 7], pencil graphite [32], graphene [33], boron-doped
diamond [3], and conductive polymers [34]. We chose nickel substrate because it
is important for the micro-component industry, in multilayer coating formation.
Moreover, nickel is used in industry as an underlayer before copper layer deposition.
Copper nucleation was studied in different electrolytes, both nonaqueous [19]
and aqueous electrolytes, such as sulfate [8, 10, 15, 25], chloride [35], perchlorate [3, 36, 37], tetrafluoroborate [38], methanesulfonate [39], as well as complex,
EDTA [40], glycinate [18], tartrate [41], pyrophosphate [9, 42, 43], and ammonia [2]. The nucleation processes in polyligand electrolytes [20, 44], which are an
active instrument to influence the coating properties [45–47], have been studied a
little.
In this chapter we analyze the process of copper nucleation and growth in
additive-free polyligand pyrophosphate-ammonia electrolyte. Pyrophosphateammonia copper-containing component was used in the development of electrolyte
for copper-nickel multilayer coating formation. Such polyligand electrolyte has
high buffer capacity, good throwing power, and the ability to deposit on an
electronegative substrate and produce coatings that simultaneously possess high
mechanical and anticorrosive properties [48, 49].
28.2 Experimental
All solutions were prepared from analytical grade chemicals and distilled water
without further treatment. Pyrophosphate-ammonia polyligand electrolyte for the
copper deposition contained 0.1 mol L −1 CuSO 4 · 5H 2 O, 0.22 mol L −1 K 4 P 2 O 7 ,
and 0.77 mol L −1 NH 3 (NH
+
4 ). The pH of solution was adjusted to 9.25 by H 2 SO 4
and KOH solutions.
Electrochemical measurements were carried out in the three-electrode cell using
a potentiostat PI-50.1. The results were transferred from analogue form to digital
by means of the two-channel voltmeter and TeleMax program for PC (100 signals
per second). Cyclic voltammograms (CVA) were obtained at a potential scan rate of
50 mV s −1 . The working electrodes were made of nickel. Before each measurement,
the electrode surface was updated by the treatment with carbide-silicone paper
(500, 1000, 2000, and 3000 grit, sequentially), cleaned by sonication in distilled
water and cathodically polarized to obtain reproducible results in the range of the
potentials corresponding to the surface oxide reduction process. The Pt electrode