IPC 7711A.pdf - 第220页
5. Mix the epoxy. If desired, add color agent to the mixed epoxy to match the printed wiring board color. 6. Apply a small amount of epoxy to the edges of the slot. A mixing stick sharp- ened at the end may be used to ap…
OUTLINE
This method is used to repair minor damage to a key slot, or other cutout in a printed
board or assembly. The area is repaired using high strength epoxy.
CAUTION
Care should be taken to limit the application of epoxy to the specific areas desired
and to avoid damage to the conductive patterns, contacts and components.
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
Color Agent, Various Colors
Epoxy
Hand Held Drill
Polyimide Tape
Knife
Milling Machine
Mixing Sticks
Oven
Precision Drill Press
Scraper
PROCEDURE
1. Clean the area to be filled, including the edges.
2. Mill away the damaged board base material using a hand held drill and ball mill.
All damaged base board material must be removed. No fibers of laminate mate-
rial should be exposed at the surface of the keyslot. (See Figure 1.)
NOTE
To clearly see that all damaged material has been removed, flood the area with
alcohol or solvent. Damaged internal fibers of the base material will show up
clearly.
CAUTION
Abrasion operations can generate electrostatic charges.
3. Remove all loose material and clean the area.
4. Apply Polyimide tape to the surface of the printed wiring board adjacent to the
slot. The tape should protect any adjacent contacts or components.
NOTE
The printed wiring board may be preheated prior to filling the area with epoxy.
A preheated printed wiring board will allow the epoxy to easily flow and level out.
Epoxy applied to an unheated printed wiring board may settle below the printed
wiring board surface as the epoxy cures.
Figure 1 Mill away the damaged board
base material.
Figure 2 Apply epoxy to the edges of
the key slot.
Figure 3 Complete key slot repair.
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision:
Date: 2/98
Key and Slot Repair,
Epoxy Method
Number: 3.4.1
Product Class: R, W
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
--``,``,-`-`,,`,,`,`,,`---
5. Mix the epoxy. If desired, add color agent to the mixed epoxy to match the
printed wiring board color.
6. Apply a small amount of epoxy to the edges of the slot. A mixing stick sharp-
ened at the end may be used to apply the epoxy. (See Figure 2.)
NOTE
A slight overfill of epoxy may be desired to allow for shrinkage when epoxy
cures.
NOTE
The printed wiring board may be turned on its side to keep the epoxy in place
while it cures.
7. Cure the epoxy per the manufacturers instructions.
CAUTION
Some components may be sensitive to high temperature.
8. After the epoxy has cured remove the tape.
9. If needed use the knife or scraper and scrape off any excess epoxy.
10. If precision is required, machine the edges of the slot using a milling machine or
precision drill and appropriate milling cutter. Use great care to correctly relocate
the slot.
NOTE
If needed, apply additional thin coating to seal any scrapped areas.
11. Clean the area.
EVALUATION
1. Visual examination and measurement of key slot location and dimension.
NOTES
IPC-7721A
Number: 3.4.1
Revision:
Date: 2/98
Subject: Key and Slot Repair, Epoxy 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 modify or repair a key slot, or other cutout in a printed board
or assembly. A replacement piece of matching board material is epoxied into the
area needing repair. A new cut is then machined into the repaired area if needed.
CAUTION
Care should be taken to limit the application of epoxy to the specific areas desired
and to avoid damage to the conductive patterns, contacts and components.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking and Preheating
2.6 Epoxy Mixing and Handling
TOOLS & MATERIALS
Ball Mills, Carbide
Base Material, Various Sizes
Carbide Saw
Cleaner
Cleaning Wipes
Epoxy
End Mills
Hand Held Drill
Polyimide Tape
Knife
Milling Machine
Mixing Stick
Oven
Precision Drill Press
Scraper
PROCEDURE
1. Clean the area to be filled, including the edges.
2. Mill out the damaged area using a milling machine or precision drill system and
carbide end mill. (See Figure 1.)
CAUTION
Abrasion operations can generate electrostatic charges.
3. Clean the area.
4. Install carbide saw into the hand held drill. Set the speed to maximum and
machine a groove in the edge of the printed wiring board where the new base
material will be installed. The groove must be centered in the edge to ensure
that the new piece will fit properly. The groove width should be approximately
1/3 of the printed wiring board thickness. The groove depth should be be
approximately double the groove width. (See Figure 2.)
5. Cut a piece of replacement base board material that is the same thickness and
type as the printed wiring board. The replacement piece should be longer than
the length of the slot to allow for ease of handling.
Figure 1 Mill out damaged area using
a carbide end mill.
Figure 2 Cut a groove into both sides
of the key slot.
Figure 3 Machine a tongue onto both
sides of replacement material.
Figure 4 Insert the replacement piece
into the slot.
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision:
Date: 2/98
Key and Slot Repair,
Transplant Method
Number: 3.4.2
Product Class: R, W
Skill Level: Expert
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
--``,``,-`-`,,`,,`,`,,`---