FPC Thin-Gold Surface Protection

The production problem

Thin-gold FPC samples may look acceptable after plating but develop discoloration, local corrosion or exposed underlayer during storage, humidity or corrosion testing.

Diagnostic sequence

1. Confirm whether the finish is ENIG or electroplated gold and record the actual gold thickness.
2. Review nickel condition, post-plating rinsing and drying before evaluating a protective treatment.
3. Use untreated and treated coupons from the same production lot.
4. Check downstream soldering, bonding or electrical-contact requirements.

Control direction

• Stabilize the base finish and cleaning process first.
• Select hydrophilic or hydrophobic surface behavior according to downstream processing.
• Compare appearance, corrosion and functional results under identical exposure conditions.

Validation before production release