IPC 7711A.pdf - 第221页
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 machin…
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
--``,``,-`-`,,`,,`,`,,`---
6. Install an end mill into the chuck of the drill press. Machine a tongue onto both
sides of the replacement piece. The dimensions of the tongue should match the
size of the milled groove. (See Figure 3.)
7. Where required apply tape to protect exposed parts of printed wiring board
bordering the prepared area.
8. Carefully check the fit of the replacement piece and then clean both the replace-
ment piece and the slot. The replacement base material should fit firmly into the
slot so that it will not move or fall out when epoxied in place.
9. Apply tape to the surface of the printed wiring board adjacent to the slot. The
tape should protect any adjacent contacts or components.
10. Mix the epoxy.
11. Apply a small amount of epoxy to the edges of the replacement piece and to
the inside edges of the slot.
12. Insert the replacement piece into the slot. Check alignment. Remove excess
epoxy. (See Figure 4.)
13. If needed, apply additional epoxy to the edges of the slot. A wood stick sharp-
ened at the end may be used to apply the epoxy.
14. Cure the epoxy per the manufacturers instructions.
CAUTION
Some components may be sensitive to high temperature.
15. After the epoxy has cured remove the tape.
16. If needed use the knife or scraper and scrape off any excess epoxy.
NOTE
If needed, apply additional thin coating to seal any scrapped areas.
17. Clean the area.
18. Cut off excess length of replacement material and file to match contour of exist-
ing edge. (See Figure 5.)
19. If a new slot is needed, machine using milling machine and appropriate milling
cutter. Use great care to correctly relocate the slot.
20. Clean the area.
EVALUATION
1. Visual examination and measurement of key slot location and dimension.
NOTES
Figure 5 Cut off excess material and
file to match edge.
IPC-7721A
Number: 3.4.2
Revision:
Date: 2/98
Subject: Key and Slot Repair, Transplant 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
--``,``,-`-`,,`,,`,`,,`---