Circuit Board Repair and Rework Guide > 2.0 Basic Procedures > 2.4.2 Coating Replacement, Conformal Coating, Encapsulant

2.4.2 Coating Replacement, Conformal Coating, Encapsulant

Printed Board Type: R/F/W/C | Skill Level: Intermediate | Conformance Level: High | Rev.: D

Outline

This method is used to replace conformal coatings and encapsulants on circuit boards.

Acceptability References
IPC-A-600	2.0	Externally Observable Characteristics
IPC-A-610	10.0	Laminate Conditions
Procedure References
CTC	1.0	Foreword
CTC	2.1	Handling Electronic Assemblies
CTC	2.2.1	Cleaning, Local
CTC	2.2.2	Cleaning, Aqueous Batch Process
CTC	2.3.1	Coating Removal, Identification of Coatings
CTC	2.4.1	Coating Replacement, Solder Mask
CTC	2.5	Baking and Preheating
CTC	2.7	Epoxy Mixing and Handling
IPC 7721	2.4.2	Coating Replacement, Conformal Coatings / Encapsulants
Tools and Materials
Brushes Cleaner Color Agents Epoxy Foam Swabs		Heat Lamp Microscope Oven Replacement Coating Wipes

Conformal Coating Required
At Outlined Area

Procedure

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

Figure 2: Coating complete.

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 Kapton tape to outline the area where the soldermask 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.