Printed Board Type: R/F/W/C
Skill Level: Intermediate
Conformance Level: High
Revision: D
Revision Date: Jan 5, 1998

OUTLINE
This method is used to replace solder mask or coatings on circuit boards. Most replacement coatings can be applied by dipping, brushing or spraying.

ACCEPTABILITY REFERENCES
IPC-A-600 2.0	Externally Observable Characteristics
IPC-A-610 10.0	Laminate Conditions
PROCEDURE REFERENCE
1.0	Foreword
2.1	Handling Electronic Assemblies
2.2	Cleaning
2.3.1	Coating Removal, Identification Of Coatings
2.4.2	Coating Replacement, Conformal Coatings/Encapsulants
2.5	Baking and Preheating
2.7	Epoxy Mixing and Handling
IPC7721 2.4.1	Coating Replacement, Solder Resist

TOOLS & MATERIALS
Brushes
Cleaner
Color Agents
Epoxy
Foam Swabs
Heat Lamp
Microscope
Oven
Replacement Coating
Wipes

PROCEDURE

1. Soldermask Required At Outlined Area

   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 Kapton tape to outline the area where the soldermask will be applied.
   
   
3. Mix the epoxy or replacement coating. If desired, add color agent to the mixed epoxy to match the circuit board color.
   
   
4. Apply the replacement coating to the board surface as required. A brush or foam swab may be used to apply and spread the epoxy or replacement coating. (See Figure 1).
   
   

5. Figure 1: For large surfaces, apply the replacement coating with a foam swab to create a texture.

   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.