IPC 7711A - 第248页
6. Clean the area. 7. Select a wire to match the width and thickness of the conductor to be replaced. Cut a length approximately as needed. See Table 1 for Solid Wire Equivalents. 8. Strip the wire and tin the ends if ne…
OUTLINE
This method is used on printed wiring boards to replace damaged or missing con-
ductors on the printed wiring board surface. A length of standard insulated or non-
insulated wire is used to repair the damaged conductor.
CAUTION
The conductor widths, spacing and current carrying capacity must not be reduced
below allowable tolerances.
CAUTION
This method is not acceptable when wire will be subsequently subjected to a mass
soldering operation.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking and Preheating
TOOLS AND MATERIALS
Cleaner
Knife
Liquid Flux
Dental Style Drill
Microscope
Solder
Soldering Iron with Tips
Wipes
Solid Wire
PROCEDURE
1. Clean the area.
2. Remove the damaged section of conductor using the knife. The damaged con-
ductor should be trimmed back to a point where the conductor still has a good
bond to the printed wiring board surface.
NOTE
Heat can be applied to the damaged conductor using a soldering iron to allow
the conductor to be removed more easily.
3. Use a knife and scrape off any solder resist or coating from the ends of the
remaining conductor. (See Figure 1.)
4. Remove all loose material. Clean the area.
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.
Figure 1 Scrape off any coating from
ends of remaining conductors.
Figure 2 Drill through board adjacent
to conductor.
Figure 3 Drill through board, through
conductors.
Figure 4 Lap solder wire to
conductor.
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision: A
Date: 11/99
Conductor Repair,
Through Board
Wire Method
Number: 4.2.5
Product Class: R
Skill Level: Advanced
Level of Conformance: Medium
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.
Page1of4
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. Clean the area.
7. Select a wire to match the width and thickness of the conductor to be replaced.
Cut a length approximately as needed. See Table 1 for Solid Wire Equivalents.
8. Strip the wire and tin the ends if needed. Non-insulated wire may be used for
short repairs if conductors are not crossed.
9. Clean the wire.
CAUTION
Review conductor diagrams to be sure no surface or internal conductors will be
damaged or shorted.
10. Drill through the board, either adjacent to both ends of the remaining conduc-
tors or through the conductors. Drill the hole slightly larger than the wire diam-
eter to be used. (See Figure 2.)
11. Position the wire on the opposite side from the repair and insert the stripped
ends into the drilled holes.
12. Bend the stripped wire over the prepared conductors in line with the conduc-
tors. The wire should overlap the existing conductor a minimum of 2 times the
conductor width. (See Figure 3.)
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.
13. Apply a small amount of liquid flux to the overlap joint.
14 Lap solder the wire to the conductors on the printed wiring board surface. Make
sure the wire is properly aligned. (See Figure 4.)
15. Form the wire on the opposite side to match the shape of the missing conduc-
tor.
16. Clean the area.
NOTE
It may be necessary to encapsulate the solder joint connection if electrical spac-
ing is reduced.
Table 1 Solid Wire Equivalents
Conductor Width 2 oz. Copper Equivalent Solid Wire Diameter
0.25 mm #34, 0.15 mm
0.38 mm #32, 0.20 mm
0.50 mm #31, 0.23 mm
0.78 mm #29, 0.28 mm
2.08 mm #26, 0.46 mm
3.18 mm #23, 0.58 mm
When using solid wire to repair a conductor, there should be no reduction in the
cross sectional area.
IPC-7721A
Number: 4.2.5
Revision: A
Date: 11/99
Subject: Conductor Repair, Through Board Wire 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
--``,``,-`-`,,`,,`,`,,`---
17. If desired bond the wire to the printed wiring board surface with adhesive, epoxy
or Tape Dots.
CAUTION
Some components may be sensitive to high temperature.
18. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
19. After the epoxy has cured clean the area.
EVALUATION
1. Visual examination for alignment and overlap of wire.
2. Electrical tests as applicable.
IPC-7721A
Number: 4.2.5
Revision: A
Date: 11/99
Subject: Conductor Repair, Through Board Wire 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
--``,``,-`-`,,`,,`,`,,`---