OVERVIEW
Synthesis of ferric chloride (FeCl₃) solution for use as a PCB etchant. This practical chemistry project produces a useful reagent for electronics fabrication.
THE REACTION
Method 1 - From iron and chlorine: 2Fe + 3Cl₂ → 2FeCl₃ Method 2 - From ferrous chloride oxidation: 2FeCl₂ + Cl₂ → 2FeCl₃ Method 3 - From iron and HCl with oxidizer: Fe + 2HCl → FeCl₂ + H₂ 2FeCl₂ + 2HCl + H₂O₂ → 2FeCl₃ + 2H₂O
PCB ETCHING
Ferric chloride is one of the most common etchants for PCB fabrication. It dissolves copper through an oxidation reaction:
Cu + 2FeCl₃ → CuCl₂ + 2FeCl₂
The solution can be regenerated by re-oxidizing the ferrous chloride back to ferric chloride, extending its useful life.
ADVANTAGES
- Fast etching rate at elevated temperatures
- Clean, consistent results
- Solution can be regenerated
- Widely available if synthesis isn't practical
SAFETY
Caution: Ferric chloride is corrosive and will stain skin and clothing. It is harmful if ingested. Work in well-ventilated area with appropriate PPE. Neutralize waste before disposal.