How to remove oils before plating

Removing oils and grease before plating is critical for good adhesion and defect-free plating.

 

Author: Marisa

Removing oils and grease before plating is critical for good adhesion and defect-free plating. Here’s a step-by-step guide to effective oil removal:

1. Mechanical Cleaning (For Heavy Oils & Grease)

• Wire brushing/sanding: Removes thick grease, rust, and scale.

• Vapor blasting/abrasive blasting: Effective for complex parts.

• Ultrasonic cleaning (for small parts): Uses high-frequency sound waves to dislodge oils.

2. Solvent Degreasing (For Light Oils)

• Vapor degreasing (Trichloroethylene, Perchloroethylene) – Effective but environmentally hazardous (use only where permitted).

• Immersion in solvents (Acetone, Isopropyl Alcohol, or specialized alkaline cleaners) – Wipe or soak parts, then rinse.

3. Alkaline Cleaning (Most Common for Plating)

• Hot alkaline soak cleaning (60–80°C):

  • Sodium hydroxide (NaOH) – Strong degreaser (5–10%).

  • Sodium carbonate (Na₂CO₃) – Mild, buffered cleaner.

  • Surfactants – Help emulsify oils.

• Electrocleaning (Reverse or Direct Current):

  • Cathodic (Reverse) electrocleaning (part as cathode) – Removes organic contaminants but can cause hydrogen embrittlement.

  • Anodic electrocleaning (part as anode) – Removes light soils and smuts.

  • Typical conditions: 6–12 V, 3–10 A/dm², 1–3 minutes.

4. Emulsion Cleaning (For Stubborn Oils)

• Uses surfactants to emulsify oils into water.

• Common in spray or immersion systems.

5. Acid Cleaning (For Oxide & Oil Removal)

• Acid pickling (HCl or H₂SO₄) – Removes rust and light oils.

• Acid-based degreasers – Combine acid + surfactants for dual action.

6. Verification of Oil Removal

• Water Break Test:

  • Dip part in clean water; if water sheets evenly, it’s clean.

  • If water beads, oil is still present.

• White Glove Test: Wipe with a clean white cloth – no residue should appear.

Best Practices

• Multiple stages: Often combine solvent → alkaline → electroclean → acid.

• Rinsing: Always rinse thoroughly between steps (DI water preferred).

• Agitation: Improves cleaning (ultrasonic, mechanical, or air agitation).

• Temperature: Hotter solutions clean faster but may evaporate quickly.

Common Mistakes to Avoid

• Insufficient rinsing – Leads to contamination carryover.

• Over-relying on solvents – Some leave residues; alkaline cleaning is often better.

• Skipping electrocleaning – Critical for high-quality plating.

By following these steps, you ensure a perfectly clean surface for plating, preventing peeling, blistering, or poor adhesion. Let me know if you need details on a specific method!