Circuit Board Repair Guide > Conductor Repair Procedures > 4.2.4 How to Repair a Damaged Conductor Using a Surface Jumper Wire

How to Repair a Damaged Conductor Using a Surface Jumper Wire

Repair Circuit Boards | Repair SMT Pads | Repair BGA Pads | Repair Lands | Repair Edge Contacts
Repair a Conductor | Plated Hole Repair | Base Board Repair | Replace Solder Mask or Coatings

This procedure is used on printed circuit boards to replace damaged or missing circuits on the PC board surface. A length of standard insulated or non insulated wire is used to repair the damaged circuit.

Caution
The circuit widths, spacing and current carrying capacity must not be reduced below allowable tolerances.

IPC Acceptability References
IPC-A-610 11.0 Discrete Wiring
 
Damaged conductor needs replacement
Damaged Conductor

Related Procedure References
CTC 1.0 Foreword - Circuit Board Repair Guide
CTC 2.1 Handling Electronic Assemblies
CTC 2.2.1 How to Clean a Circuit Board
CTC 2.2.2 Cleaning Circuit Boards, Aqueous Batch Process
CTC 2.5 Baking and Preheating of Printed Circuit Boards
CTC 2.7 Epoxy Mixing and Handling
CTC 6.1 How to Use Jumper Wires
IPC7721 4.2.4 Conductor Repair, Surface Wire Method

Tools and Materials
Cleaner
Epoxy
Flux, Liquid      
Knife
Microscope      
Oven
Scraper
Solder
Soldering Station      
Wire Dots
Tape, Kapton
Wipes
Wire
Wire Guide

4.2.4 Conductor Repair, Surface Wire Method

Printed Board Type: N/A  |  Skill Level: Intermediate  |  Conformance Level: Medium  |  Rev.: D  |  Rev. Date: Jul 7, 2000

Scrape off solder mask from circuits

Figure 1: Scrape off any solder
mask or coating from the ends of
the remaining circuits.
1. 
Clean the area.
 
2. 
Remove the damaged section of circuit using the knife. The damaged circuit should be trimmed back to a point where the circuit still has a good bond to the PC board surface.
 
  Note
Heat can be applied to the damaged circuit using a soldering iron to allow the circuit to be removed more easily.
 
3.  Use a knife and scrape off any solder mask or coating from the ends of the remaining circuit. (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 circuit. Tin the exposed end of each circuit using solder and a soldering iron
 
6.  Clean the area.
   
Lap solder wire to end of circuit

Figure 2: Lap solder the wire to
one end of the circuit on the circuit board surface.









7.  Select a wire to match the width and thickness of the circuit to be replaced. Cut a length approximately as needed. See Table 1 for Solid Wire Equivalents.
   
      Table 1 - Solid Wire Equivalents

Conductor Width
2 oz. Copper
Equivalent Solid
Wire Diameter
.010" (0.25 mm) #34, .006" (0.15 mm)
.015" (0.38 mm) #32, .008" (0.20 mm)
.020" (0.50 mm) #31, .009" (0.23 mm)
.031" (0.78 mm) #29, .011" (0.28 mm)
.082" (2.08 mm) #26, .018" (0.46 mm)
.125" (3.18 mm) #23, .023" (0.58 mm)
When using solid wire to repair a conductor, there should be no reduction in the cross sectional area.
   
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.
   
10. If the wire is long or has bends, one end may be soldered prior to forming the new shape. Place the wire in position. The wire should overlap the existing circuit a minimum of 2 times the circuit width. The wire may be held in place with Kapton tape during soldering.
   
  Note
If the configuration permits, the overlap solder joint connection should be a minimum of 3.00 mm (0.125") from the related termination. This gap will minimize the possibility of simultaneous reflow during soldering operations. Refer to 7.1 Soldering Basics.
   
11. Apply a small amount of liquid flux to the overlap joint.
   
12. Lap solder the wire to one end of the circuit on the circuit board surface. Make sure the wire is properly aligned. (See Figure 2).


Form wire using wire guide

Figure 3: Form wire using a Wire Guide


13. Bend the wire as needed to match the shape of the missing circuit. (See Figure 3).
 
Note
A Wire Guide can be used to form the wire as needed.
Form wire shape and solder in place

Figure 4: Form the final shape of
the wire and solder in place.


14. Lap solder the other wire end to the remaining circuit on the circuit board surface using solder and a soldering iron. Make sure the wire is properly aligned. (See Figure 4).
   
15. Remove any Kapton tape and clean the area.
   
  Note
It may be necessary to encapsulate the solder joint connection if electrical spacing is reduced or the connection is beneath a component.
Bond wires to surface with Wire Dots

Figure 5: Bond the wires to the
surface with adhesive or Wire Dots.

16. If desired bond the wire to the circuit board surface with adhesive, liquid circuit board epoxy or Wire Dots. (See Figure 5). Refer to Procedure 6.1.
   
  Caution
Some components may be sensitive to high temperature.
   
17. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
   
18. After the epoxy has cured clean the area.
   
Evaluation
   
1.  Visual examination for alignment and overlap of wire.
   
2.  Electrical tests as applicable.




Links to Related Products


Circuit board epoxy for ciruit repair  
Circuit Bond Kit 115-1322: Liquid circuit board epoxy
Circuit Bond Kit contains 10 packages of clear, low viscosity, superior strength epoxy ideal for circuit board use. The epoxy is precisely measured out into two-compartment plastic packages. This adhesive is easy to use and there's no measuring.

Color Agents for Circuit Boards
Matching epoxy to the color of the circuit board being repaired is easy when you use a color agent. Color agents may also be applied directly to the circuit board surface for color matching.


Flextac Wire Dots bond jumper wires to circuit boards  
Flextac Wire Dots
Finally a neat and fast way to bond jumper wires to circuit boards. Flextac Wire Dots are made from flexible polymer film coated on one side with a high performance, electronics grade permanent pressure sensitive adhesive. Now you can throw away that super glue and give your operators something new thatís so much easier and faster.



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