HIRANUMA APPLICATION DATA

Automatic Titrator

Data No.

E7

Nov. 28,
2018

Determination of Tin (Sn2+) insolder plating solution

PLATING &ETCHING
SOLUTION

1. Abstract
Tin (Sn2+) in solder plating solution is determined by redox titration with iodine. Solder plating solution
contains Sn (II) ions, Sn (IV) ions, and acids etc. Iodine works as oxidizing agent for stannous ion. Sn (II) ionsare readily oxidized by oxygen in the air to be Sn (IV) ions. The measurement environment under carbon
dioxide or nitrogen gas could provide reliable results.
Sn2+＋I2→Sn4+ ＋2I-

This report introduces a measurement example that sample is added to solution under carbon dioxide gas
generated by the decomposition of sodium hydrogen carbonate, and titrated with iodine titrant.

2. Configuration of instruments and reagents(1) Configuration of instruments
Main unit: Hiranuma Automatic Titrator

COM seriesElectrodes: Platinum electrodePT-301

Reference electrodeRE-201Z*The following electrodes are also useable instead of the above electrode.
・PR-701BZ (Platinum reference electrode)・Combination of PT-301 (Platinum electrode ) andGR-501BZ (Glass-reference electrode)(2) Reagent
Titrant: 0.05 mol/L Iodine standard solution

Additive solution: Diluted sulfuric acid
50 mL of sulfuric acid is gently added to 100 mL of DI water.
: 5 % Sodium hydrogen carbonate solution
Dissolve 25 g of sodium hydrogen carbonate in DI water and diluted to 500 mL.

3. Measurement procedure(1) Take 30 mL of DI water into a 100 mL beaker.
(2) Add 5 mL of diluted sulfuric acid
(3) Carefully add 20 mL of 5 % sodium hydrogen carbonate solution because it foams vigorously.
(4) Add 1 mL of sample into the beaker with volumetric pipette.
(5) Immerse electrodes to start titration with 0.05 mol/L iodine standard solution.

4. Measurement conditions and results
Example of titration condition
Cndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mL
D.P. mLEnd Sens
Over mL
Max.Vol.

1Auto
12mV
5
00.1
300
0.3
20sec
mL
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL
Unit
FormulaDigitsAuto In Pram.

11.0000 mL
0.0000 mL
0.05 mol/L
1.007
118.7
0.000g/L

Mode No.
Pre Int
Del K
Del Sens
Int TimeInt Sens
Brt SpeedPulse

50503
32400.05

secmVsecmVmL(D-B)*K*F*M/S
3None

Measurement results
Number ofMeasurement
123Size(mL)
111

Titrant
Volume (mL)
2.376
2.405
2.376

Statistic
calculation

Avg.
SD
RSD

Sn (II) ion
Concentration (g/L)
14.20014.37414.20014.3 g/L
0.1005 g/L
0.70 %

Example of titration curve

5. NoteThe following tips could improve measurement accuracy.
(1) Influence on air oxidation of Sn (II) ionThis titration should be performed under anaerobic environment because Sn (II) ions are readily oxidized byoxygen in the air and its concentration is decreased. The carbon dioxide generated by the decomposition ofsodium hydrogen carbonate prevented the oxidation of Sn (II) ions in this report.
(2) Influence of interfering component
Solder plating solution contains Sn (IV) ions and acids etc. These components don’t interfere the measurementof Sn (II) ion. However, the reducing agents such as sodium thiosulfate and sodium sulfite react with iodine, itcauses positive error.
Keywords: Solder plating solution, Sn (II) ion, Iodine, Redox titration
Some measurement would not be possible depending on optional configuration of system.