| HIRANUMA APPLICATION DATA | Automatic Titrator | Data No. | E9 | Oct. 7,2022 |
| PLATING & ETCHING SOLUTION | Determination of hydrogen peroxide and sulfuric acid in etching solution |
1. Abstract
Sulfuric acid and hydrogen peroxide are main components of the etching solution which is used for cleaning the copper surface (soft etching) or half etching. The concentration of sulfuric acid and hydrogen peroxide have to be properly controlled to maintain constant etching speed because hydrogen peroxide readily decomposes by itself. This report introduces a measurement example as below.
1) Determination of sulfuric acid by neutralization titration with sodium hydroxide・・・(1)
2) Determination of hydrogen peroxide by redox titration with potassium permanganate standard solution.・・・ (2)
| H₂SO₄ ＋ 2NaOH → Na₂SO₄ ＋ H₂O | ・・・(1) |
| 5H₂O₂ ＋ 2KMnO₄ ＋ 3H₂SO₄ → K₂SO₄ ＋ 2MnSO₄ ＋ 8H₂O ＋ 5O₂ | ・・・(2) |
2. Configuration of instruments and Reagents
| (1) | Configuration | ||
| Main unit | : | Hiranuma Automatic Titrator COM series | |
| Option | : | Buret, buret head, and simple dispenser (peristaltic type), one by one | |
| Electrodes | : | Glass reference combination electrode GR-501BZ Connect to IE-1. Platinum electrode PT-301 Connect to IE-2. |
|
| (2) | Reagents | ||
| Titrant | : | 0.1 mol/L sodium hydroxide standard solution (for sulfuric acid titration) 0.02 mol/L potassium permanganate standard solution (for hydrogen peroxide titration) |
|
| Additive solution | : | 10 mL of diluted sulfuric acid (1:9, v/v) (for pH adjustment) | |
3. Measurement procedure
| (1) | Dispense 1 mL of sample into a 200 mL beaker with volumetric pipette. |
| (2) | Add about 100 mL of DI water. |
| (3) | Immerse electrodes and start titration with 0.1 mol/L sodium hydroxide standard solution. |
| (4) | After that, 10 mL of diluted sulfuric acid is automatically dispensed. (Option: Simple dispenser) |
| (5) | Titrate with 0.02 mol/L potassium permanganate standard solution. (Option: Buret) |
4. Measurement conditions and results
Examples of titration conditions
(1) Titration of sulfuric acid
(2) Dispensing diluted sulfuric acid
| Cndt No. | 2 | |
| Method | Disp | |
| Buret No. | 2 | |
| S-Timer | 0 | sec |
| Disp.Vol. | 10 | mL |
(3) Titration of hydrogen peroxide
Measurement results
| Number of Measurement |
Size (mL) |
Titrant volume (mL) |
Sulfuric acid (g/L) |
Titrant volume (mL) |
Hydrogen peroxide (g/L) |
|---|---|---|---|---|---|
| 1 | 1.0000 | 27.155 | 133.701 | 16.479 | 28.1676 |
| 2 | 1.0000 | 27.182 | 133.834 | 16.492 | 28.1898 |
| 3 | 1.0000 | 27.197 | 133.908 | 16.523 | 28.2428 |
| Statistical result | Avg. | 133.81 g/L | Avg. | 28.20 g/L | |
| SD | 0.10 g/L | SD | 0.04 g/L | ||
| RSD | 0.08 % | RSD | 0.14 % | ||
Examples of titration curves
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 |
| Measurement of sulfuric acid | Measurement of hydrogen peroxide |
5. Note
Potassium permanganate standard solution is used for hydrogen peroxide titration in this report because copper ion (Cu²⁺) coexists in the sample. If the sample does not contain copper ion (Cu²⁺) or iron ion (Fe³⁺) which oxidize iodine ion, the determination of hydrogen peroxide with the iodometry method using sodium thiosulfate titrant is also possible.
Keywords: Etching solution. Sulfuric acid, Neutralization titration, Hydrogen peroxide, Potassium permanganate
*Some measurement would not be possible depending on optional configuration of system.
