Masking FAQs
Review our Masking FAQS and understand how masking protects keep-out areas during conformal coating and Parylene deposition. This page brings together all masking topics—boots, tape, dots, and custom shapes—so you can quickly choose the right method for your design and volume.
Overview of masking in conformal coating
What is masking and why is it needed?
Masking protects areas of a PCB that must remain free of coating (e.g., connectors, test points, sockets). Without masking, coating can cause poor electrical connections, soldering issues, or rework problems. Effective masking improves quality, reliability, and standards compliance. See also our Process FAQs (inspection).
Which masking method should I choose?
The choice depends on production volume, geometry, and cost. Tape and dots suit low-volume or prototypes, while silicone boots and custom shapes cut labour and improve consistency in higher volumes (for Parylene or liquid coatings). Many processes use a mix of methods for best efficiency. Related: Selective coating equipment.
Masking boots
When are silicone masking boots better than tape?
Boots are ideal in medium-to-high volume because they’re reusable and fast to apply/remove, with less residue risk versus adhesive tapes. The higher upfront cost is usually offset by labour savings. This is common for liquid chemistries and Parylene.
How do I size, clean, and reuse boots?
Choose a snug fit to prevent bleed-under. After use, clean in approved solvents or aqueous cleaners to remove residue; inspect for wear. With proper care, a silicone boot can last through many cycles. See cleaning & reliability.
Masking tape
What tape types work best and how to avoid residue?
Use tapes designed for conformal coating—typically polyester tapes with silicone-free adhesives for liquid coatings to avoid contamination. For Parylene, Kapton® tapes are preferred (vacuum & high-temp stable). Remove tape promptly after cure/deposition to minimise transfer. See Materials FAQs.
Tips to prevent edge lift and bleed-under
Roll down firmly, avoid stretching during application, and ensure surfaces are clean/dry. Overlap pieces for sharp edges or irregular shapes, or switch to dots/shapes for consistency. Related: application methods.
Masking dots
When should I use dots instead of tape?
Dots protect pads, vias, or holes where tape is awkward or slow. They give consistent coverage and speed on repetitive layouts; custom die-cuts can further improve repeatability. Pair with spray application for selective coverage.
Masking shapes
Benefits of custom die-cut shapes
Custom shapes match board features, reducing operator error and time versus manual taping. They deliver consistent results across batches and boost throughput—especially helpful with complex geometries or where masking load is high.
