Outline
This method is used to replace solder masks or coatings on circuit boards. Most replacement coatings can be applied by dipping, brushing, or spraying.
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.| Procedure References | |
| 1-0 | 1.0 Foreword |
| 2-1 | 2.1 Handling Electronic Assemblies |
| 2-2 | 2.2 Cleaning Procedures |
| 2-3-1 | 2.3.1 Coating Removal, Identification of Coating |
| 2-4-2 | 2.4.2 Coating Replacement, Conformal Coating, Encapsulant |
| 2-5 | 2.5 Baking and Preheating |
| 2-7 | 2.7 Epoxy Mixing and Handling |
Tools and Materials
Clear, superior strength epoxy in two-compartment plastic packages. |
General purpose cleaner for removing contamination. |
Disposable brushes for solvent cleaning and application of coatings. |
Replacement soldermask and conformal coatings. |
One part, semi-paste ink used to tint the color of epoxy and for direct printing on circuit board surfaces. |
Sturdy rack for PCBs used for rework and positioning. |
Swabs for use with solvents and application of color agents and epoxies. |
Precision microscope with stand and lighting for work and inspection. |
General purpose oven for drying, baking and curing epoxies. |
Nine precision-crafted tools for detailed circuit board work. |
Training kit to practice circuit board repair skills prior to testing for certification. |
Nonabrasive, low-linting wipes for cleanup. |
Procedure
- Clean the area.
Caution: Surfaces to be coated must be thoroughly cleaned before coating to ensure adequate adhesion, minimized corrosion, and optimized electrical properties. - If needed, apply High-Temperature Tape to outline the area where the solder mask will be applied.
- Mix the epoxy or replacement coating. If desired, add a color agent to the mixed epoxy to match the circuit board color.
- 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 2)
- Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
Caution: Some components may be sensitive to high temperatures.
Evaluation
- Visual examination for texture, color match, adhesion, and coverage.
- Electrical tests to conductors around the repaired area as applicable.
Images
Coating Replacement, Solder Mask
Identify the area requiring solder mask replacement
If needed, apply tape to outline the area where the solder mask will be applied.
Apply the replacement solder mask to the board surface as required. A brush or foam swab may be used to apply and spread the coating.
