1. Bath Basics
Acid copper bath: copper sulfate 60-100 g/L, sulfuric acid 180-250 g/L, chloride 50-80 ppm, proprietary brightener per supplier; temperature 20-30°C; current density 2-4 A/dm² (with air agitation); anodes: phosphorus copper (0.03-0.06% P) for stable dissolution. Continuous filtration (5-10 µm) and periodic carbon treatment maintain bath health.
2. Rough Plating
Cause: excessive current density (edge roughness); low temperature or insufficient brightener in winter; poor cleaning of reworked panels;
Solution: reduce current; verify with a current meter; raise temperature/add brightener per Hull-cell; clean panels properly before re-plating.
3. Copper Particles on the Board Surface
From electroless copper (seeding): hard water, drilling dust, poor degreasing, impure micro-etch chemicals (use ≥CP grade), high copper or low temperature in the micro-etch bath, contaminated activator (long service), turbid accelerating solutions (fluoroboric-acid-based attacking FR-4 glass);
From the plating bath: H₂SO₄ too high or Cu²⁺ too low, temperature outside range (copper-powder formation), excessive current (poor contacts, fallen boards, dissolving against anode), phosphorus-content problems in copper anodes, poor anode-bag cleaning; use 5-10 µm PP anode bags and clean anodes with hydrogen-peroxide micro-etch during major treatment;
Solution: control each pre-treatment stage; filter continuously; maintain anode quality; major treatment (carbon + peroxide) as scheduled.
4. Pitting (Leakage Plating)
Causes: contaminated electroless-copper baskets dripping Pd-Cu onto panels; dirty brushing/air-knife equipment; dust before lamination/printing; poorly maintained developer; hard-water turbidity in acid pre-treatments; stripped hanger coatings contaminating the bath;
Solution: dedicated rack maintenance, frequent tank cleaning, filtered process water, dust control, and weekly bath checks.
5. Whitish or Uneven Colour
Causes: air-blowing pipe displaced (uneven agitation); filter-pump air ingress (fine bubbles adsorbed); contaminated filter cores (anti-static agents); brightener imbalance or organic contamination; bath temperature too high; poor water quality/oxidation after pre-soak;
Solution: reposition air pipes, purge filter lines, use qualified filter media, control brightener by Hull cell, maintain temperature, and improve rinse water quality.
6. Prevention Programme
Daily: current density, temperature, agitation, anode condition;
Weekly: Hull-cell test, chloride/brightener analysis; filtration check;
Monthly: carbon treatment; anode bag cleaning; pre-treatment tank replacement schedule;
Document all parameters for traceability.
