Outline
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.
Cleaner
General purpose cleaner for removing contamination.
Cleaning Brushes
Disposable brushes for use with solvents for cleaning and application of coatings.
Coatings
Replacement soldermask and conformal coatings.
Color Agents
Use to tint the color of epoxy used for solder mask repair or circuit base board repair.
Circuit Bond Epoxy
Clear, superior strength epoxy in two-compartment plastic packages
Foam Swab
Ideal for absorbing cleaning solvents, and applying color agents and epoxies.
Microscope
Precision microscope with stand and lighting for work and inspection.
Oven
General purpose oven for drying, baking and curing epoxies.
Wipes
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.
Procedure
Clean the area.
Caution
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.
Caution
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.
