Coating masking process

The coating masking process is a critical step before applying Conformal Coating in PCB Assembly and SMT Assembly. It involves protecting specific areas of a PCB that must remain free of coating to ensure proper functionality and connectivity.

Why masking is necessary

Not all parts of a PCB should be covered with Conformal Coating. Certain components and areas must remain exposed for electrical or mechanical reasons.

Common areas to mask:

• Connectors and sockets
• Switches and buttons
• Test points and probes
• Edge connectors (gold fingers)
• Heat sinks and mechanical interfaces

Masking ensures that these areas remain functional after coating in PCB Assembly.

Types of masking materials

Different masking materials are used depending on production requirements:

Masking tapes

• Easy to apply and remove
• Suitable for flat surfaces

Liquid masking (peelable mask)

• Applied as a liquid, then cured
• Ideal for complex shapes and irregular areas

Silicone plugs and boots

• Used for connectors and through-holes
• Reusable and precise

Custom fixtures or tooling

• Used in high-volume SMT Assembly
• Improves efficiency and repeatability

Masking process steps

The masking process typically includes:

• Identify areas that must not be coated
• Apply masking materials carefully
• Inspect masking for accuracy and coverage
• Proceed with Conformal Coating application
• Remove masking after coating and curing

Proper masking ensures clean boundaries and avoids defects.

Manual vs automated masking

Manual masking

• Flexible and low cost
• Suitable for small batches
• Labor-intensive and time-consuming

Automated/selective coating (masking reduction)

• Uses precise machines to avoid sensitive areas
• Reduces or eliminates masking
• Common in modern SMT Assembly lines

Common masking challenges

• Incomplete masking → unwanted coating contamination
• Improper removal → residue or damage
• Misalignment → functional issues
• Increased labor cost in manual processes

Careful planning and quality control are essential.

Final conclusion

The coating masking process is essential in PCB Assembly and SMT Assembly to protect critical areas from Conformal Coating. By using proper masking materials and techniques, manufacturers can ensure functionality, improve coating quality, and reduce defects in electronic products.

Get a Conformal Coating Quote

Working on automotive, industrial, or outdoor electronics? We can help with conformal coating.
Send us your requirements and get a fast response from our engineering team.

✔ 24-hour response    ✔ Engineering support    ✔ Small & Mass Production

Please enable JavaScript in your browser to complete this form.

Name

Email *

WhatsAPP

Preferred Material

• Acrylic (AR)
• Silicone (SR)
• Polyurethane (UR)
• UV Curable - UV
• I'm not sure / Need advice

File upload

Drag & Drop Files, Choose Files to Upload You can upload up to 8 files.

Please compress all Gerber files, Drill files, and BOM into a single .ZIP or .RAR file for faster processing.

Email Preferred File

Message

"Please list components or areas that must NOT be coated (e.g., connectors, test points)." If you have specific coating material requirements (e.g., HumiSeal), please mention it in the message box below.

Submit

Shenzhen Tengxinjie Electronics Co., Ltd.