Determination of Indium and Tin Content in Etching Solution by Wayeal Atomic Absorption Spectrophotometer

Variations in the concentrations of indium and tin in the etching solution directly affect the etching rate and pattern precision. By determining their contents, the etching conditions can be precisely controlled to avoid incomplete or excessive etching caused by concentration fluctuations, thereby ensuring product yield. Furthermore, both indium and tin are rare metals, with indium being particularly expensive. The detection enables the determination of whether the etching solution has reached its "end of life," which not only avoids waste caused by premature replacement but also allows for monitoring of metal concentrations in the waste solution, facilitating efficient recovery and reuse, and significantly reducing production costs.

Meanwhile, as the etching process proceeds, the dissolved indium and tin will continuously accumulate. Regular determination allows for monitoring the degree of bath aging, enabling the decision of whether to replenish with fresh solution or replace the entire bath, thereby maintaining the continuity and stability of the production line.

The waste solution containing indium and tin is classified as hazardous material. Accurate determination of their contents is an essential step in wastewater treatment, regulatory reporting, and compliance with environmental emission standards, which helps enterprises conduct proper disposal in accordance with regulations and avoid environmental risks.

Keywords: Atomic absorption; graphite furnace method; etching solution; indium; tin.

1. Experiment Method

1.1 Instrument Configuration

Table 1 Configuration List of the Atomic Absorption Spectrophotometer

1.2 Reagents and Experimental Materials

1.2.1 Indium standard solution: 1000mg/L;

1.2.2 Tin standard solution: 1000mg/L;

1.2.3 Hydrochloric acid: guaranteed reagent;

1.2.4 Nitric acid: guaranteed reagent;

1.2.5 Perchloric acid: guaranteed reagent;

1.2.6 Polytetrafluoroethylene (PTFE) crucible;

1.2.7 Digital display electric hot plate.

2. Result and Discussion

2.1 Spectral Conditions for the Elements

2.1.1 Standard Curve Testing

Standard Curve of Indium

Standard Curve of Tin

2.1.2 Test Results of a Certain Sample

3. Attention

3.1 During sample pretreatment, the hydrochloric acid, nitric acid, and perchloric acid added are all strong acid solutions; proper protective measures shall be taken. This entire process must be operated in a fume hood.

4. Conclusion

The experimental results showed that the linear correlation coefficients for both indium and tin are greater than or equal to 0.999. This method is accurate, reliable, and highly sensitive, and can be used for the determination of indium and tin in samples.