IPC 7711A.pdf - 第241页
OUTLINE This procedure is used to repair short breaks or opens in conductors on printed wir- ing boards. A parallel gap welder is used to weld a jumper ribbon across the dam- aged conductor. CAUTION Welding current and v…
NOTES
IPC-7721A
Number: 4.2.2
Revision:
Date: 2/98
Subject: Conductor Repair, Foil Jumper, Film Adhesive 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
--``,``,-`-`,,`,,`,`,,`---
OUTLINE
This procedure is used to repair short breaks or opens in conductors on printed wir-
ing boards. A parallel gap welder is used to weld a jumper ribbon across the dam-
aged conductor.
CAUTION
Welding current and voltages may affect component reliability on assembled printed
wiring boards.
CAUTION
The repaired section must not reduce the conductor width, spacings or current car-
rying capacity below the allowable tolerances.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.6 Epoxy Mixing and Handling
PREPARATION
Prior to using any welding equipment, certain precautions should be taken. The
equipment should have electrodes cleaned, aligned and set for the proper board
thickness.
Test samples that have similar conductor widths, spacing, thickness, surface finish,
contour, etc. Observe and test the weld quality, alignment, discoloration, fusion and
the appearance of the base material in the area of the weld. Readjust the weld
equipment settings and repeat until acceptable results have been achieved.
The alignment of the welded ribbon to the conductor pattern should be within 0.050
mm. The weld bond strength should exceed the conductor/base material bond
strength.
TOOLS & MATERIALS
Cleaner
Cleaner Wipes
Epoxy
Knife
Kovar Ribbon
Liquid Flux
Microscope
Parallel Gap Welder
Ribbon - Gold Plated Kovar
Solder
Soldering Iron
Tweezers
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision:
Date: 2/98
Conductor Repair,
Welding Method
Number: 4.2.3
Product Class: R, F, C
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
--``,``,-`-`,,`,,`,`,,`---
PROCEDURE
1. Clean the area.
2. Select a section of Kovar ribbon of the same width as the conductor pattern
being repaired ± .050 mm.
3. Cut the ribbon approximately 3.0 mm longer than the section being repaired.
4. Clean the ribbon conductor and base material surrounding the repair area.
5. Place and center the ribbon over the section to be repaired leaving equal ribbon
end lengths on each side and parallel to the conductor pattern.
6. Place the printed wiring board under the weld electrodes so that the electrodes
are depressed to the area of the weld.
7. Hold the ribbon in place with tweezers until the weld is completed. Weld in place
using settings based on the accepted test samples.
8. Clean the area.
9. Carefully inspect the joint for weld quality and alignment.
10. If required, apply a small amount of flux and tin the entire area with solder.
11. Clean the area.
12. Coat the repaired area with epoxy if needed.
EVALUATION
1. Visual examination, dimensional measurement of conductor width and spacing,
and electrical continuity measurement.
NOTES
IPC-7721A
Number: 4.2.3
Revision:
Date: 2/98
Subject: Conductor Repair, Welding 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
--``,``,-`-`,,`,,`,`,,`---