2.4.2 Coating Replacement, Conformal Coating, Encapsulant
This method is used to replace conformal coatings and encapsulants on circuit boards.
Minimum Skill Level - Intermediate
Recommended for technicians with skills in basic soldering and component rework, but may be inexperienced in general repair/rework procedures.
Conformance Level - High
This procedure most closely duplicates the physical characteristics of the original, and most probably complies with all the functional, environmental and serviceability factors.
Tools and Materials
General purpose cleaner for removing contamination.
Disposable brushes for use with solvents for cleaning and application of coatings.
Replacement soldermask and conformal coatings.
Use to tint the color of epoxy used for solder mask repair or circuit base board repair.
Ideal for absorbing cleaning solvents, and applying color agents and epoxies.
Precision microscope with stand and lighting for work and inspection.
General purpose oven for drying, baking and curing epoxies.
Nonabrasive, low-linting wipes for cleanup.
Images and Figures
Conformal Coating Required At Outlined Area
Figure 1: For large surfaces, apply the replacement coating with a foam swab to create a texture.
Figure 2: Coating complete.
Clean the area.
Surfaces to be coated must be thoroughly cleaned prior to coating to ensure adequate adhesion, minimized corrosion, and optimized electrical properties. If needed, apply High Temperature Tape to outline the area where the coating will be applied.
If required, bake the circuit board prior to the application of the replacement coating.
Mix the replacement coating.
Apply the replacement coating to the board surface as required. A brush or foam swab may be used to apply and spread the replacement coating. (See Figure 1)
Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
Some components may be sensitive to high temperature. Evaluation
Visual examination for texture, color match, adhesion and coverage.
Electrical tests to conductors around the repaired area as applicable.
Procedure for reference only.