Overview
Electrodeposited copper foil — for Li-ion batteries, PCBs and high-frequency boards — is grown from a CuSO₄ - H₂SO₄ electrolyte bath. Cu²⁺ concentration, free acid level and trace additives (gelatin, thiourea, chloride) govern thickness uniformity, tensile strength and surface roughness. With Li-battery foil now at 4.5-6μm, plants run dozens of parallel deposition drums and demand exceptional sensor stability, acid resistance and precision.
Process challenges
- Strongly acidic electrolyte (pH < 1) at 50-60°C — PFA / titanium / tantalum wetted parts required
- Additives at ppm level — beyond resolution of conventional density meters
- 4.5-8μm foil trend leaves no tolerance for process drift
- Recirculating bath carries fine bubbles — interferes with non-ultrasonic principles
- Multi-drum lines need unified communication to MES
Recommended solutions
| Measurement point | Principle | Models |
|---|---|---|
| Cu²⁺ concentration in electrolyte main | Ultrasonic sound velocity + T compensation | PS7020 |
| Free-acid (H₂SO₄) return line | Ultrasonic sound velocity / optical | PS7020 / PS7110 |
| Additive dosing buffer tank | Coriolis | PS7200 |
| Post-treatment surface bath | Ultrasonic / optical | PS7020 / PS7110 |