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2.4.2 Coating Replacement, Conformal Coating, Encapsulant
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.

Acceptability References
IPC-A-600 2.0 Externally Observable Characteristics
IPC-A-610 10.0 Laminate Conditions
Procedure References
1.0 Foreword
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.3.1 Coating Removal, Identification Of Coatings
2.4.1 Coating Replacement, Solder Mask
2.5 Baking and Preheating
2.7 Epoxy Mixing and Handling
IPC7721 2.4.2 Coating Replacement, Conformal Coatings/Encapsulants
Tools and Materials
CircuitMedic Part
Alcohol Swab
Self-saturating Isopropyl alcohol swab. Squeeze handle to release alcohol.
Cleaner
Cleaner
General purpose cleaner for removing contamination.
CircuitMedic Part
Cleaning Brushes
Disposable brushes for use with solvents for cleaning and application of coatings.
115-9000 Color Agents
Coatings
Replacement soldermask and conformal coatings.
Color Agent
Color Agents
Use to tint the color of epoxy used for solder mask repair or circuit base board repair.
CircuitMedic Part
Circuit Bond Packs
Clear, superior strength epoxy in two-compartment plastic packages
CircuitMedic Part
Foam Swab
Ideal for absorbing cleaning solvents, and applying color agents and epoxies.
Microscope
Microscope
It is a challenge to undertake precision repair without a good microscope.
Oven
Oven
General purpose oven for drying, baking and curing epoxies.
Wipes
Wipes
Nonabrasive, low-linting wipes for cleanup.
Images and Figures
2.4.2 Coating Replacement, Conformal Coating, Encapsulant
Conformal Coating Required At Outlined Area
2.4.2 Coating Replacement, Conformal Coating, Encapsulant
Figure 1: For large surfaces, apply the replacement coating with a foam swab to create a texture.
2.4.2 Coating Replacement, Conformal Coating, Encapsulant
Figure 2: Coating complete.

Procedure

  1. 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.

  2. If needed, apply High Temperature Tape to outline the area where the coating will be applied.

  3. If required, bake the circuit board prior to the application of the replacement coating.

  4. Mix the replacement coating.

  5. 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)

  6. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling

    Caution
    Some components may be sensitive to high temperature.

Evaluation

  1. Visual examination for texture, color match, adhesion and coverage.

  2. Electrical tests to conductors around the repaired area as applicable.

Procedure for reference only.