No. 2.6.1
Legend/Marking, Stamping 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 an ink stamp
to place the legends on the printed board surface in much the same manner as
taking a "finger print".
TOOLS & MATERIALS
Cleaner
Color Agent/Epoxy Ink
Ink Plate
Ink Roller
Microscope
Oven
Peg Stamps
Knife
Wipes
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 characters from the peg stamp set or have a special
stamp made up.
- 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.
- Gently press the peg stamp into the epoxy coating to coat the character
surface.
- Gently press the peg stamp onto the desired location on the circuit board
surface. (See Figure 1).
- Cure the epoxy ink per the manufacturer's instructions.
EVALUATION
- Visual examination for proper characters, positioning and legibility.
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Solutions Across the Board
TM
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Product Class: R/F/W/C
Skill Level: Intermediate
Conformance Level: High
Revision: C
Revision Date: Jul 1, 1997
Repair Service Charge
Damaged Legend
Figure 1: Apply legend using a peg stamp.
Figure 2: Completed legend repair.
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Tricks of the Trade
A relatively simple process. Peg stamps can usually be obtained
from a local office supply store. The epoxy ink used is specifically designed
for legend application.
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Real Problems, Real Solutions
This project completed by Circuit Technology Center involved a
change to an etched part number on 146 assembled circuit boards valued at $96
each. The new part number had several different characters from the existing
number, so the entire old number had to be removed and replaced. The old part
number was removed by applying heat from a soldering iron that allowed each
character to be peeled off with a knife. A one piece peg stamp was made
including all 9 characters of the new part number. Adding the new part number
was straightforward. These boards were headed to the scrap bin if the number
could not be removed and replaced. Rework charge was $14.00 per board.
Total Value $14,016 - Total Rework Charge $2,044 = Total Savings $11,972
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