Conformal Coating Defects Hub

Conformal coating defects can undermine PCB protection, reduce insulation resistance, and cause costly rework or field failures. This hub explains the most common defects, their causes, and how to prevent them, linking to detailed technical articles and inspection guidance.

Defect Index to the Articles

Defect	Fast Link	Full Article
Pinholes, Bubbles & Foam	Fast Link	Full Article ↗
Orange Peel	Fast Link	Full Article ↗
Dewetting	Fast Link	Full Article ↗
Delamination	Fast Link	Full Article ↗
Cracking	Fast Link	Full Article ↗
Corrosion & Ionic Contamination	Fast Link	Full Article ↗
Capillary / Wicking	Fast Link	Full Article ↗

Pinholes, Bubbles & Foam

Gas entrapment during application or curing leaves voids that weaken protection and allow moisture ingress. This is one of the most common coating defects seen during inspection.

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Orange Peel

A dimpled, textured surface caused by viscosity imbalance, spray atomisation issues, or poor substrate energy. This coating flaw can trap contaminants and affect appearance.

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Dewetting

The coating film pulls back into “islands,” leaving bare areas. This typically arises from silicone, oil, or surfactant contamination lowering surface energy during application.

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Delamination

Loss of adhesion between the coating and substrate. Often caused by poor surface preparation, moisture ingress, or thermal stress, leading to coating reliability issues.

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Cracking

Fractures appear in the coating when it is applied too thick, becomes brittle, or experiences CTE mismatch. Cracking creates pathways for moisture and contaminants.

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Corrosion & Ionic Contamination

Residual ions combine with moisture and bias to enable electrochemical migration and dendritic growth. This failure mechanism is one of the most damaging to PCB reliability.

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Capillary / Wicking Around Components

Capillary flow draws the coating into gaps and under parts, breaching keep-out zones. This causes unwanted meniscus lines and can interfere with functionality.

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Related Standards & Guidance

For further reading on coating defects and acceptance criteria, see:
NASA Conformal Coating Workmanship Guidelines.

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