Cu and Ni Depostion Throwing Power
Cu and Ni Depostion Throwing Power
Cu and Ni Depostion Throwing Power
r-
XT
July 28, 1924
1 - Introduction
'U
In both electroplating and electroforming 1 it is desirable
2
Further details will be found in an article by H. E. Haring
and W. Blum - Trans. Am, Electrochem, Soc. Vol. 44, 313, (1923)
and one by H. E. Haring, Vol, 46, (1924). ,
2 -- Principles
Whenever an irregularly shaped article is made the cathode
in a plating solution, certain parts are -closer to the anode
than are others. The resistance through the solution from
the anode to a near part is less than to a far part, and the
current density (e.g. in amperes per square foot) will be
greater upon the near part than upon the far part. If then
the resistance through the solution were the only factor which
'
\
,
If however
the metal ratio is 6 to 1, it is less uniform than the primary
ratio, hence the throwing -oower is negative, in this case -20
per cent.
0,445
4.30
C. 106
Primary ratio (as used in box) = 5,00. Deviation of metal
ratio froai primary ratio = 5,00 - 4,30 = 0,80, Throwing
power (deviation in percent) =
0,80
x 100 = +16^
5.00
If in another solution (e.g, nickel) the deposits on the two
plates weighed 0,432 g and 0,080 g reject ively, the uietal
ratio is -re/ngS - 5 40, Therefore the distribution is less
.
0.080
uniform than the -primary ratio, and the throwing rower is
0.40 100 = - 8 $.
4 - Results Obtained
(Table 1)
(3)
Cu rr ent Density - The throwing power is decreased
-
as the current density is raised.
(Table 2)
The most significant result of the experiments on copper
cyanide solutions is that in them the throwing power is
from 30 to 40 per cent, as compared with 2 to 18 per cent in
,
6 6 .
Table 1
Throwing Power of Copper Sulphate Solutions
Temperature 70° E
Addition Standard + 0
Agents aluminum sulphate 0 27 5.73 8.4
Standard +
dextrose 13.3 5,50 7.0
Standard +
dextrin 1.3 4. 54 12.2 5.6
Standard +
gelatin 0.03 4.47 18.0 10.4
*” Standard" solution
^ Total current used on the two plates in the box^ with a com-
bined area of 33 sq.in,
2
Crystallized, salts
i . ; ,
Table 2
Total, current used on the two plates in the box., with a com-
bined area of 32 sq.in.
"Throwing Power* 1
in Copper and Nickel Deposit ion-9 7/28/34
C - Nickel Solutions
(Tables 3 and 4)
Table 3
Total current used on the two plates in the box, with a com-
bined area of 32 so. in 4
n 0
Table 4
Throwing Power of Nickel Solutions
Results of Changes in Solution Composition
0 Standard +
sodium sulnhite 0. 13 21 4,8 9.0
Impurities P Standard +
cadmium chloride 0.015 21 6.0 -2.6
Q Standard 4-
copper sulnhate 0.017 21 28.0 3.4
R Standard -+•
c -
Hydrogen Peroxide This is an oxidizing agent, the
.
higher
low current densities* but has little effect at the
o
current densities. In general the injurious exf ec - s
a
such metallic impurities will be most pronounc°a , ,
5 - Conclusion
three fac
Because the throwing power is the resultant of
tors, each of which may vary with different metals*
s0
genei p
t ions or conditions, it is difficult to make any
for improving throwing power. It is possible
few simple measurements in the apparatus described
mine the probable direction and magnitude of the e
any specified change in conditions* and thus be gui. e
their proper selection.
improvement
In any case, it should be remembered that an
re ^ r S
in throwing power as here defined and measured*
a i 0 WPr
simply a more uniform distribution of metal, i.e,
minimum
con sump ti on of metal to produce any specified
ness of denosit on the article. Frequently however l