Outline
This method can be used to add, change, or replace legends and markings on printed boards or printed board assemblies. It uses epoxy ink and a brush or roller technique. A stencil is used to outline the characters.
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 |
| 2-5 | 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. |
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. |
A must-have tool for precise cutting, scraping and trimming. |
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. |
Nonabrasive, low-linting wipes for cleanup. |
Procedure
- Clean the area.
- Scrape off any remaining character or legend with a knife and clean the area.
Caution: Abrasion operations can generate electrostatic charges. - Select the appropriate stencil or have a special stencil made up. (See Figure 2)
- Mix the epoxy ink. White is the most common color. Spread a thin, even coating of the epoxy ink on the ink plate or a smooth surface.
- Position the stencil on the circuit board surface and hold it in place firmly.
- Roll or brush the ink onto the stencil. Do not smudge characters or apply excess ink.
- Cure the epoxy ink per the manufacturer's instructions.
Evaluation
- Visual examination for proper characters, positioning, and legibility.
Images
Legend/Marking Repair, Stencil Method
Scrape off any remaining character or legend with a knife and clean the area.
Position a stencil on the circuit board surface and roll or brush the ink to replace the missing legend
Cure the epoxy ink per the manufacturer's instructions.
