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2.6.3 Legend Marking, Stencil Method
Outline
This method can be used to add, change or replace legend and markings on printed boards or printed board assemblies. This method 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.

Acceptability References
IPC-A-600 2.0 Externally Observable Characteristics
IPC-A-610 8.0 Marking
Procedure References
1.0 Foreword
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking And Preheating
2.7 Epoxy Mixing and Handling
IPC7721 2.6.3 Legend/Marking, Stencil Method
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.
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
Knife with #16 Blades
A must-have tool for precise cutting, scraping and trimming.
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
2.6.3 Legend Marking, Stencil Method
Damaged Legend
2.6.3 Legend Marking, Stencil Method
Figure 1: Replace legend using a stencil.
2.6.3 Legend Marking, Stencil Method
Figure 2: Completed legend repair.

Procedure
  1. Clean the area

  2. Scrape off any remaining character or legend with a knife and clean the area.

    Caution
    Abrasion operations can generate electrostatic charges.

  3. Select the appropriate stencil or have a special stencil made up. (See Figure 1)

  4. Mix the epoxy ink. White is the most common color. Spread a thin even coating of the epoxy ink on the ink plate or on a smooth surface.

  5. Position the stencil on the circuit board surface and hold in place firmly

  6. Roll or brush the ink onto the stencil. Do not smudge characters or apply excess ink.

  7. Cure the epoxy ink per the manufacturer's instructions.

Evaluation

  1. Visual examination for proper characters, positioning and legibility.

Procedure for reference only.