Parylene PCB Layout Guidelines

Design rules for component placement, spacing and vapour access

Parylene PCB layout guidelines define how components, spacing and geometry influence coating coverage, masking complexity and long-term reliability. Although Parylene is deposited from the vapour phase and is highly conformal, poor PCB layout can still create shadowing, inaccessible regions and inconsistent coating thickness.

This guide explains the most common PCB layout issues seen in Parylene coating and how to design assemblies that support reliable, repeatable and manufacturable Parylene coating.

Infographic illustrating parylene PCB layout guidelines, showing component spacing, vapour access, shadowing risks, connector placement and masking-friendly design rules.

Core PCB layout guidelines that enable reliable, repeatable Parylene coating coverage.

Why PCB Layout Matters for Parylene Coating

Layout guidelines are critical for Parylene because vapour-phase deposition still depends on physical access to surfaces. Layout decisions directly affect:

  • Uniformity of Parylene coating under components
  • Risk of shadowed or thinly coated areas
  • Masking feasibility and cost
  • Inspection access and defect detection

Assemblies designed without Parylene PCB layout rules often require rework, additional masking or process compromises.

Component Spacing & Density Guidelines

Good Parylene PCB layout guidelines prioritise spacing that allows vapour access:

  • Avoid tightly packed component clusters where possible
  • Provide clearance beneath large or low-profile components
  • Consider standoff height for BGAs, connectors and shields

Increasing spacing slightly at design stage often reduces coating risk and masking cost later.

Vapour Access, Shadowing & Tall Components

Shadowing occurs when components block line-of-sight vapour flow. Common causes include:

  • Tall connectors or housings adjacent to small components
  • Vertical walls or dense mechanical features
  • Enclosures that limit vapour circulation

Effective Parylene PCB layout guidelines ensure that critical surfaces remain accessible to the vapour stream throughout the deposition cycle.

PCB Layout & Masking Design Interaction

PCB layout and masking design are tightly linked. Layout should:

  • Group features that require masking
  • Avoid isolated, tiny keep-out areas
  • Support the use of standard boots, caps and fixtures

Following Parylene PCB layout guidelines at concept stage reduces masking labour, variability and defect risk.

Design-for-Manufacturability Considerations

Manufacturable PCB layouts for Parylene coating consider:

  • Consistent orientation and fixturing
  • Handling points that avoid coated surfaces
  • Clear inspection access after coating

A layout that coats successfully once may still fail in volume if manufacturability is not considered.

Why Work with SCH on Parylene PCB Layout Design?

SCH supports customers applying Parylene PCB layout guidelines through:

  • Design-led reviews focused on spacing, access and manufacturability
  • Turnkey capability covering coating services, equipment and materials
  • Cross-sector experience in medical, aerospace, automotive and industrial electronics
  • Clear scale-up pathways from prototype to production

Call: +44 (0)1226 249019 Β· Email: sales@schservices.com
Contact SCH to discuss your PCB layout for Parylene coating β€Ί

Disclaimer: This article provides general guidance on Parylene PCB layout guidelines. Performance, suitability and compliance depend on the specific design, materials and application environment. SCH Services can review assemblies and specifications to confirm the most appropriate Parylene coating approach.