IPC 7711A - 第210页

NOTES IPC-7721A Number: 2.7.3 Revision: Date: 2/98 Subject: Legend/Marking, Stencil Method P a g e2o f2 Copyright Association Connecting Electronics Industries Provided by IHS under license with IPC Not for Resale No rep…

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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.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking and Preheating
2.6 Epoxy Mixing and Handling
TOOLS & MATERIALS
Cleaner
Cleaning Wipes
Epoxy Ink
Ink Plate
Ink Roller
Knife
Microscope
Oven
Stencil
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 printed wiring 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.
Figure 1 Replace legend using a
stencil.
Figure 2 Completed legend repair.
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision:
Date: 2/98
Legend/Marking,
Stencil Method
Number: 2.7.3
Product Class: R, F, W, C
Skill Level: Intermediate
Level of Conformance: High
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
NOTES
IPC-7721A
Number: 2.7.3
Revision:
Date: 2/98
Subject: Legend/Marking, Stencil Method
Page2of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
OUTLINE
This method is used to repair mechanical or thermal blisters or delaminations in
printed wiring board laminated base materials. The blister is sealed by injecting a low
viscosity epoxy into the blister/delamination void.
CAUTION
This method can only be used when the laminate base material has separated suf-
ficiently to allow the epoxy to flow throughout the void area.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking and Preheating
2.6 Epoxy Mixing and Handling
TOOLS & MATERIALS
Ball Mill, #1/2
Cleaner
Cleaning Wipes
Epoxy
Epoxy Cartridge with Tip
Epoxy Injection System, Optional
Hand Held Drill
Heat Lamp
Oven
Scraper
Vacuum Source, Optional
PROCEDURE
1. Clean the area.
2. Drill into delamination blister with the dental style drill and ball mill. Drill in an area
clear of circuitry or components. Drill at least two holes opposite each other
around the perimeter of the delamination. (See Figure 1.) Brush away all loose
material.
CAUTION
Be careful not to drill too deep exposing internal conductors or planes.
CAUTION
Abrasion operations can generate electrostatic charges.
3. Bake the printed wiring board to remove any entrapped moisture. Do not allow
the printed wiring board to cool prior to injecting the epoxy.
CAUTION
Some components may be sensitive to high temperature.
4. Mix the epoxy. See manufacturers instructions on how to mix epoxy without
bubbles.
Figure 1 Drill into the delamination
blister
Figure 2 Inject epoxy into the
delamination blister.
Figure 3 Completed Repair.
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision:
Date: 2/98
Delamination/Blister
Repair, Injection Method
Number: 3.1
Product Class: R
Skill Level: Advanced
Level of Conformance: High
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---