How to Dip Coat a PCB | Conformal Coating Step-by-Step Guide

Dip tank setup, viscosity control, immersion and withdrawal rate, curing and inspection

Dip coating can deliver uniform, wrap-around coverage for complex assemblies, but repeatable results depend on more than immersion. Cleaning, masking, viscosity control, immersion profile, withdrawal rate, drainage and curing all determine whether the finished coating is consistent and defect-free.

This guide explains the practical steps involved in dip coating a PCB and sits alongside the wider technical articles on dip coating process behaviour, film formation and stability and dip coating equipment settings and process control variables.

Used correctly, dip coating is scalable and repeatable. Poor control leads to capillary wicking, air entrapment, runs, edge pooling, de-wetting and under-component retention that often only becomes visible after cure or in service.

Dip coating PCB process infographic showing 6 steps: cleaning, masking, viscosity control, immersion, withdrawal, curing and inspection

Simple 6-step dip coating process showing how cleaning, masking, viscosity control, immersion, withdrawal, curing and inspection combine to deliver consistent conformal coating results.

1) Tools & Materials

  • Dip-grade conformal coating
  • Dip tank with controlled lift and withdrawal
  • Viscosity cup and thermometer
  • Filtration and tank covers
  • Masking materials such as tapes, boots or liquid mask
  • PPE and extraction
  • Inspection tools and witness coupons

For thickness measurement methods, see wet, dry and optical coating thickness measurement methods.

โ†‘ Back to Quicklinks

2) Clean & Prepare

Coating only adheres to clean, dry surfaces. Remove flux, contamination and moisture, particularly under components and in connectors.

Poor preparation often shows up later as de-wetting, fish-eyes, weak edge coverage or local adhesion failure. For deeper guidance, see surface preparation and cleanliness for reliable conformal coating.

โ†‘ Back to Quicklinks

3) Mask Keep-Out Areas

Mask connectors, interfaces and protected zones using appropriate barrier or reusable masking systems.

One of the main risks here is capillary draw into interfaces during dip and drain. For broader context, see why masking creates many coating defects.

โ†‘ Back to Quicklinks

4) Set Viscosity & Tank Conditions

  • Control viscosity within a defined window
  • Maintain temperature stability
  • Prevent contamination
  • Track solvent additions and bath condition

For practical guidance, see how viscosity is measured and controlled in a coating process.

โ†‘ Back to Quicklinks

5) Dip & Withdraw

  • Immersion: too fast can trap air and later cause bubbles or frog-eye type defects
  • Withdrawal: strongly influences film thickness
  • Drainage: must clear under components rather than leaving heavy retained build
  • Orientation: influences pooling and wicking
Critical: retained coating under components can create mechanical stress during cure and thermal cycling, particularly where CTE mismatch exists. This can contribute to cracking or, in more severe cases, component lift.

For the full process model behind film formation, drainage, geometry effects and stability, see dip coating process behaviour, film formation and stability. For a more settings-focused view, see dip coating equipment settings and process control variables.

โ†‘ Back to Quicklinks

PCB being dip coated showing controlled immersion, withdrawal and drainage behaviour

Controlled dip coating depends on cleaning, masking, viscosity, immersion discipline, withdrawal control and drainage behaviour.

6) Flash-Off & Cure

  • Allow controlled drainage and solvent release
  • Build thickness in thin layers where required
  • Follow the material cure profile

โ†‘ Back to Quicklinks

7) Inspection & Quality Control

  • Check coverage and edges
  • Inspect under components
  • Verify thickness
  • Use witness coupons appropriately

See how coating thickness is verified in production and how witness boards and test coupons support coating validation.

โ†‘ Back to Quicklinks

9) Training & Standards

Repeatable, audit-ready dip coating depends on operator training, not just written instructions.

  • IPC-A-610
  • IPC-CC-830

Contact SCH Services

โ†‘ Back to Quicklinks

Why Choose SCH Services?

SCH Services supports dip coating process development, production troubleshooting, training and equipment selection with practical engineering input built around real manufacturing constraints.

Where dip coating is being considered, SCH can help assess whether the process is robust enough for the assembly, the coating chemistry and the required production outcome.

โ†‘ Back to top

Disclaimer:

General technical guidance only. Final process settings, inspection criteria, material compatibility and production suitability should always be confirmed through appropriate engineering trials, validation work and applicable customer or industry standards.