Circuit Board Repair Guide > Conductor Repair Procedures > 4.2.5 How to Repair Damaged Conductors Using a Jumper Wire

How to Repair Damaged Conductors Using a 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 printed circuit 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.

Caution
This method is not allowed when wire will be subsequently subjected to a mass soldering operation.

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

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 4.2.5 Conductor Repair, Through Board Wire Method

Tools and Materials
Cleaner
Flux, Liquid      
Knife
Micro Drill System      
Microscope
Solder
Soldering Station      
Wire Dots
Wipes
Wire
Wire Guide

4.2.5 Conductor Repair, Through Board Wire Method

Printed Board Type: R  |  Skill Level: Advanced  |  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.
   
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.
   
Drill through board adjacent to circuits

Figure 2: Drill through the board adjacent to both ends of the
remaining circuits.


10.
Drill through the board adjacent to both ends of the remaining circuits. Drill the hole slightly larger than the wire diameter to be used. (See Figure 2).
   
 
Caution
Review circuit diagrams to be sure no surface or internal circuits will be damaged or shorted.
Bend stripped wire over circuits

Figure 3: Bend the stripped wire
over the prepared circuits in line
with the circuits.


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 circuits in line with the circuits. The wire should overlap the existing circuit a minimum of 2 times the circuit width. (See Figure 3).
   
 
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.
Lap solder wire to circuits

Figure 4: Lap solder the wire to
the circuits on the circuit board surface.
13. Apply a small amount of liquid flux to the overlap joint.
   
14.
Lap solder the wire to the circuits on the circuit 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 circuit, if desired.
   
16. Clean the area.
   
 
Note
It may be necessary to encapsulate the solder joint connection if electrical spacing is reduced.
   
17.
If desired bond the wire to the circuit board surface with adhesive, circuit epoxy or Wire Dots. Refer to Section 6.0.
   
  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.




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.


Micro Drill System used for drilling, grinding, cutting circuit boards  
Micro Drill System 110-4105
The Micro Drill System is a repair technician's dream and is ideal for milling, drilling, grinding, cutting and sanding circuit boards. It removes coating, cuts circuits, cuts leads, drills holes, cuts slots, shapes FR4 and performs many other procedures using various interchangeable bits. Unlike most hand-held tools, the Micro Drill has a tiny, high speed DC motor in the hand piece, eliminating cumbersome drive cables and giving you better control. A separate power supply keeps the hand piece lightweight and reduces operator fatigue. Base unit has controls for forward/reverse and speed up to 45,000 RPM.





Copyright and Disclaimer Notice Copyright © CircuitMedic, Haverhill, MA 01835 USA

Related Items
Professional Repair Kit | Circuit Frames | PCB Tracks | Prototyping Boards | Surface Mount Resistor Kits | Surface Mount Capacitor Kits