Circuit Board Repair Guide > Basic Circuit Board Repair Procedures > 2.6.3 Legend Marking Using Stencil Method

Legend Marking Using Stencil Method

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The stencil method can be used to add, change or replace legend and markings on printed circuit boards or printed circuit board assemblies. This procedure uses epoxy ink and a brush or roller technique. A stencil is used to outline the characters.

IPC Acceptability References
IPC-A-600 2.0 Externally Observable Characteristics
IPC-A-610 8.0 Marking
 
Related Procedure References
CTC 1.0 Foreword - Circuit Board Repair Guide 
CTC 2.1 Handling Electronic Assemblies
CTC 2.2.1 How to Clean a Circuit Board
CTC 2.2.2 Cleaning Circuit Boards, Aqueous Batch Process
CTC 2.5 Baking and Preheating of Printed Circuit Boards
CTC 2.7 Epoxy Mixing and Handling
IPC7721 2.6.3 Legend/Marking, Stencil Method

Tools and Materials
Cleaner
Color Agent/Epoxy Ink
Ink Roller
Ink Plate
Microscope
Oven
Knife
Stencil
Wipes

2.6.3 Legend Marking, Stencil Method

Printed Board Type: R/F/W/C  |  Skill Level: Intermediate  |  Conformance Level: High  |  Rev.: D  |  Rev. Date: Jul 7, 2000

Damaged legend

Damaged Legend


Replace legend using stencil

Figure 1: Replace legend using a stencil.


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 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.
 
Completed legend repair

Figure 2: Completed legend repair.
Evaluation
   
1. Visual examination for proper characters, positioning and legibility.
 




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