IPC 7711A.pdf - 第235页
18. Coat the top and sides of the foil jumper with epoxy. The epoxy bonds the foil jumper to the printed wiring board surface and insulates it. A wooden stick sharpened at one end may be used to apply and spread the epox…
5. Apply a small amount of liquid flux to the ends of the remaining conductor. Tin
the exposed end of each conductor using solder and a soldering iron.
6. Clean the area.
7. Select a conductor foil jumper to match the width and thickness of the conduc-
tor to be replaced. Cut a length approximately as needed. The foil jumper
should overlap the existing conductor a minimum of 2 times the conductor
width.
NOTE
The new conductor may be trimmed from copper sheet.
8. Gently abrade the top and bottom surface of the replacement foil jumper with a
buffer to remove the protective coating.
NOTE
A thin protective coating is often applied to the replacement foil jumper to pre-
vent oxidation.
9. Clean the conductor foil jumper.
10. If needed, the ends of the replacement conductor foil jumper may be tinned with
solder prior to lap soldering it in place.
11. If the conductor foil jumper is long or has bends, one end may be soldered prior
to forming the new shape. Place the foil jumper in position. The foil jumper
should overlap the existing conductor a minimum of 2 times the conductor
width. The jumper may be held in place with Polyimide tape. (See Figure 2.)
12. Apply a small amount of liquid flux to the overlap joint.
13. Lap solder the foil jumper to the conductor on the printed wiring board surface
using solder and a soldering iron. Make sure the foil jumper is properly aligned.
NOTE
If the configuration permits, the overlap solder joint connection should be a
minimum of 3.00 mm from the related termination. This gap will minimize the
possibility of simultaneous reflow during soldering operations.
14. Bend the foil jumper as needed to match the shape of the missing conductor.
(See Figure 3.)
NOTE
Two wood sticks can be used to make sharp bends in the replacement foil
jumper. Use one stick to hold the new jumper at the bend location and use the
other wood stick to form the shape as needed.
15. Wide conductors that cannot be easily formed may be folded over to produce
a sharp bend. (See Figure 4.)
16. Form the final shape of the jumper and hold in place with tape. Lap solder the
foil jumper to the remaining conductor on the printed wiring board surface using
solder and a soldering iron. Remove the tape used to hold the foil jumper. Clean
the area. (See Figure 5.)
17. Mix the epoxy. If desired, add color agent to the mixed epoxy to match the
printed wiring board color.
Figure 5 Form the final shape of the
jumper and hold in place with tape.
Figure 6 Coat the top and sides of the
foil jumper with epoxy.
IPC-7721A
Number: 4.2.1
Revision: A
Date: 11/99
Subject: Conductor Repair, Foil Jumper, Epoxy Method
Page2of4
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
18. Coat the top and sides of the foil jumper with epoxy. The epoxy bonds the foil
jumper to the printed wiring board surface and insulates it. A wooden stick
sharpened at one end may be used to apply and spread the epoxy. (See Figure
6.)
19. Cure the epoxy per the manufacturers instructions.
CAUTION
Some components may be sensitive to high temperature.
20. Apply surface coating to match prior coating as required.
EVALUATION
1. Visual examination for alignment and overlap of foil jumper.
2. Visual examination of epoxy coating for texture and color match.
3. Electrical tests as applicable.
IPC-7721A
Number: 4.2.1
Revision: A
Date: 11/99
Subject: Conductor Repair, Foil Jumper, Epoxy Method
Page3of4
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: 4.2.1
Revision: A
Date: 11/99
Subject: Conductor Repair, Foil Jumper, Epoxy Method
Page4of4
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---