And practical steps to exorcise the chemistry gremlins.
October brings ghosts, goblins and, if you’re not careful, a few monsters lurking right inside your plating tanks. They won’t knock on your door or ring a bell, but they will hide in your agitation systems, anodes and cables. If ignored, they can turn good product into scrap before you even notice.
Here are five things that tend to haunt plating tanks, and how to exorcise them before they ruin your yield.
1. Agitation and oscillation.
Agitation directly affects deposit uniformity and surface quality. Too little flow permits the diffusion layer near the part to thicken, leading to dull deposits, pitting and low current density areas. Too much flow can cause turbulence, gas entrapment and rough deposits.
The goal is consistent, balanced movement of solution across the panels. Eductors, air spargers and mechanical oscillation systems should deliver steady flow without excessive turbulence.
Practical controls include:
- Inspect eductors for cracks, clogging or breaks.
- Record solution flow rates or air pressure on a regular schedule.
- Verify that oscillation amplitude and cycle speed match established baselines.
Uniform agitation ensures predictable plating thickness and appearance across the entire load. Consistent, even coating reduces defects customers might encounter during assembly.
2. Anode maintenance.
Anodes are often treated as static hardware, but they are active components that change over time. They’re like zombies: slowly degrading, oxidizing and shedding debris that can poison a bath if ignored. When anodes are neglected, deposits can become dull, rough or uneven.
Routine anode maintenance should include:
- Replacing or cleaning anode bags before they clog or tear.
- Inspecting anode geometry and placement for even wear.
- Re-activating passivated surfaces using dummy plating when required.
Preventing passivation and debris buildup helps maintain additive balance, which supports proper grain structure and adhesion. This ensures boards are durable and solderable for complex assemblies.
3. Amperage consistency.
Even when voltage and chemistry appear stable, uneven current distribution can lead to inconsistent plating. Common causes include corroded contacts, loose fasteners, and undersized or damaged leads that introduce hidden voltage drops. These electrical losses often cause localized thin or burned areas that appear unrelated to chemistry.
Routine checks should include:
- Measuring actual current at the plating racks and cable connections, rather than relying only on rectifier displays.
- Checking torque and cleanliness of all electrical contacts.
- Inspecting cables for temperature rise or corrosion that may indicate resistance buildup.
Maintaining even amperage protects against localized plating issues, supporting reliable product performance. If r parts show unexplained variation: check the current, not just the chemistry. A phantom voltage drop can torment a line if left unchecked.
4. Temperature control.
Temperature affects nearly every parameter of a plating bath, including metal deposition rate, grain structure and additive performance. Small deviations of only a few degrees can produce noticeable differences in appearance and stress.
Typical causes of temperature variation include dirty heat exchangers, inaccurate sensors, and uneven circulation within the tank. These issues often develop slowly and may not trigger alarms.
Best practices for control:
- Calibrate sensors regularly and replace any that show drift.
- Clean heaters, coolers and probes to maintain proper heat transfer.
- Verify temperature uniformity at multiple points within the tank.
Stable temperature control improves reproducibility and reduces defects in coverage and appearance. For customers, this means boards consistently meet specifications and perform reliably in the field.
5. Complacency vs. process oversight and documentation.
The most effective preventive measure in plating is active observation. The most dangerous phrase is “the line’s been running fine.” Most defects are not from big mistakes, but originate as small deviations in agitation, current or temperature that go unnoticed because they do not immediately affect output. By the time yields drop or appearances change, the root cause can be difficult to identify.
Operators and engineers should make a habit of recording readings and inspecting equipment regularly. Weekly logs of current, temperature, and flow provide trend data that can reveal gradual drift before it becomes a production issue. Consistent documentation also builds process understanding and improves troubleshooting efficiency.
Plating is a careful balance of science, discipline and a touch of superstition. Problems often appear quietly, like ghosts in the night, for those who fail to stay vigilant. Maintaining proper agitation, anodes, current, and temperature, and avoiding complacency, helps prevent unexpected issues from creeping into your tanks. Attention to these practices ensures consistent plating quality, predictable performance, and fewer surprises on the production floor. Keeping your process in check rewards the careful observer and keeps the “monsters” at bay.
These same measures translate directly into benefits for your customers. Boards leave the line with smooth, uniform finishes, precise metal thickness and strong adhesion. Consistent plating reduces defects, improves reliability in the field, and gives customers confidence that the products they receive will perform as intended. By focusing on both process discipline and customer impact, you protect your production and your reputation.
Kevin VanNattan is a process engineer at Summit Interconnect’s Anaheim, CA facility, with over five years’ experience in PCB manufacturing and process optimization. He oversees critical fabrication processes, guiding plating operators and lab personnel.
