JW-661 Acidic Bright Tin Plating Process
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Detailed description:
Formulation and Process Conditions
| Stannous sulfate | 20---40g/L | |
| Sulfuric acid | 120~160 g/L | |
| JW-661A (main brightener) | 8--18ml/L | |
| JW-661B (Positioning Agent) | 5--10mI/L | |
| Operating temperature | 5~25℃ | |
| Cathodic current | 1–5 A/dm² | |
| Anode | Pure tin sheet | |
Bath Preparation
1. Add 80% pure water to the plating tank, and while continuously stirring, slowly introduce the calculated amount of sulfuric acid; then allow the solution to cool to room temperature.
2. Add stannous sulfate to the plastic bucket in batches, stirring repeatedly with the plating bath’s sulfuric acid solution until completely dissolved, then pour the solution into the plating tank.
3. Add brightener JW-661A at 12 ml/L and leveling agent JW-661B at 8 ml/L; top up with water to the specified liquid level, stir thoroughly, and after a brief electrolysis, proceed with the plating test.
4. If the tin coating is not sufficiently bright after trial plating, continue adding brightener JW‑661A at 0.5 mL/L or more, and adjust until the tin coating achieves normal brightness.
Usage of Additives
The dosage of electroplating additives should be determined based on the total charge passed through the plating bath (in ampere-hours), avoiding overdosing; it is preferable to replenish frequently in small increments. The consumption rates for the two additives are 200–400 mL per kA·h.
Note:
1. Brass and zinc‑aluminum alloy are tin‑plated; special attention must be paid to the underlying structure: if a pre‑copper plating is used, the copper layer must be at least 3 microns thick; otherwise, all previous efforts will be wasted.
2. The concentration of the brightener in the plating bath can be assessed by observing the brightness of the tin coating in the low‑current areas: if the low‑current tin layer is bright, it indicates that the brightener level is adequate; conversely, if the low‑current tin layer is dull or only slightly bright, it suggests that the brightener concentration is insufficient.
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JW-661 Acidic Bright Tin Plating Process
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