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4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method

  • This method is used to replace damaged or missing circuits on the circuit board surface.
  • Remove solder mask from the connecting circuit.
  • Sample frame or replacement conductors with dry film adhesive backing.
  • Scrape off epoxy bonding film from solder joint connection area on back of new conductor.
  • Cut out the new circuit. Cut from the plated side.
  • Place the new conductor in place using high temperature tape.
  • Bond the replacement conductor using a Bonding System used to thermally bond dry film adhesive backed replacement conductors.
  • Completed repair.
Outline
This method is used to replace damaged or missing circuits on the circuit board surface.

Caution
It is essential that the board surface be extremely smooth and flat. If the base board is damaged see appropriate procedure.

Minimum Skill Level - Advanced
Recommended for technicians with soldering and component rework skills and exposure to most repair/rework procedures, but lacking extensive experience.

Conformance Level - High
This procedure most closely duplicates the physical characteristics of the original, and most probably complies with all the functional, environmental and serviceability factors.

Acceptability References
IPC-A-600 2.0 Externally Observable Characteristics
IPC-A-610 10.0 Laminate Conditions
Procedure References
1.0 Foreword
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking And Preheating
2.7 Epoxy Mixing and Handling
IPC7721 4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Tools and Materials
CircuitMedic Part
Abrader
Mild abrasive for removing oxides and contaminates from conductive surfaces.
CircuitMedic Part
Alcohol Swab
Self-saturating Isopropyl alcohol swab. Squeeze handle to release alcohol.
CircuitMedic Part
Bonding Station, 120 VAC
Delivers the optimal heat for curing adhesive bonding film.
CircuitMedic Part
Bonding System
System designed to repair lifted and damaged conductors, pads, BGA pads, SMT pads.
CircuitMedic Part
Cleaning Brushes
Disposable brushes for use with solvents for cleaning and application of coatings.
CircuitMedic Part
Circuit Bond Packs
Clear, superior strength epoxy in two-compartment plastic packages
CircuitMedic Part
High Temp Tape Discs
High temperature polyimide tape discs, .50" diameter.
CircuitMedic Part
Knife with #16 Blades
A must-have tool for precise cutting, scraping and trimming.
CircuitMedic Part
Micro Probes
Use to dispense a minute amount of adhesive and for micro-positioning of small objects.
CircuitMedic Part
Scraper
Hardened stainless steel tip for scraping solder mask and removing defects.
CircuitMedic Part
Tweezer, Point Tip
Fine point tweezers for precision work.
Images and Figures
4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Damaged Conductor
4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Figure 1: Remove solder mask from the connecting circuit.
4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Figure 2: Sample frame or replacement conductors with dry film adhesive backing.

4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Figure 3: Scrape off epoxy bonding film from solder joint connection area on back of new conductor.
4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Figure 4: Cut out the new circuit. Cut from the plated side
4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Figure 5: Place the new conductor in place using high temperature tape.

4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Figure 6: Bonding System used to thermally bond dry film adhesive backed replacement conductors.
4.2.2 Conductor Repair, Foil Jumper, Film Adhesive Method
Figure 7: Completed repair.
Procedure
  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.
  3. Use the knife and scrape off any epoxy residue, contamination or burned material from the board surface.
  4. Scrape off any solder mask or coating from the connecting circuit. (See Figure 1)
  5. Clean the area.
  6. Apply a small amount of liquid flux to the connection area on the board surface and tin with solder. Clean the area. The length of the overlap solder connection should be a minimum of 2 times the circuit width.
  7. Select a replacement circuit with film adhesive backing that most closely matches the size of the conductor to be replaced. If a special size or shape is needed it can be custom fabricated. (See Figure 2)

    Note
    New conductors are fabricated from copper foil. The foil is plated on the top side with solder and an epoxy bonding film is applied to the bottom side.
  8. Before trimming out the new conductor carefully scrape off the adhesive epoxy film from the solder joint connection area on the back of the new conductor. (See Figure 3)

    Caution
    Scrape off the epoxy backing only from the joint connection area. When handling the new conductor avoid touching the epoxy backing with your fingers or other materials that may contaminate the surface and reduce the bond strength.
  9. Cut out and trim the new conductor. Cut out from the plated side. Cut the length to provide the maximum allowable circuit overlap for soldering. Minimum 2 times the circuit width. (See Figure 4)

    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.
  10. Place a piece of High Temperature Tape tape over the top surface of the new conductor. Place the new conductor into position on the circuit board surface using tape to help in alignment. Leave the tape in place during the bonding cycle. (See Figure 5)
  11. Select a bonding tip with a shape to match the shape of the new conductor.

    Note
    The bonding tip should be as small as possible but should completely cover the entire width of the new conductor.
  12. Position the circuit board so that it is flat and stable. Gently place the hot bonding tip onto the High Temperature Tape covering the new circuit. Apply pressure as recommended in the manual of the repair system or repair kit for 5 seconds to tack the circuit in place. Carefully peel off the tape. (See Figure 6)
  13. Gently place the bonding tip directly onto the new circuit. Apply pressure as recommended in the manual of the repair system or repair kit for an additional 30 seconds to fully bond the new circuit. The new circuit is fully cured. Carefully clean the area and inspect the new circuit for proper alignment.
  14. Apply a small amount of liquid flux to the lap solder joint connection area and solder the circuit foil jumper from the new conductor to the circuit on the PC board surface. Use minimal flux and solder to ensure a reliable connection. High Temperature Tape may be placed over the top of the new conductor to prevent excess solder overflow.
  15. Mix epoxy and coat the lap solder joint connections. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.

    Caution
    Some components may be sensitive to high temperature.

  16. Apply surface coating to match prior coating as required.
Evaluation
  1. Visual examination.
  2. Measurement of new pad width and spacing.
  3. Electrical continuity measurement.
Procedure for reference only.
 

Related Products

115-1322 Circuit Bond Kit
Kit containing packages of clear, low viscosity, superior strength epoxy for circuit board damage repair.
201-3130 Circuit Track Kit
Kit to repair circuit board damage including lands and conductors.
Circuit Frames
Circuit Frames for surface mount pad, BGA pad and conductor repair.
115-4100 Bonding System
System designed to repair lifted and damaged conductors, pads, BGA pads, SMT pads.
Customer Comments
"Just wanted you to know that the quality of the boards you have repaired for us has been excellent. The boards were for a customers that doesn't normally accept any repair, but once they saw your repair work, they happily accepted them ... fantastic!"
R.D. Palm Bay, FL USA
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