Circuit Board Repair Guide > Conductor Repair Procedures > 4.6.1 How to Repair Damaged Edge Contacts Using Liquid Adhesive

How to Repair Damaged Edge Contacts Using Liquid Adhesive

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 circuit board repair procedure is used to replace a damaged edge contact with a new edge contact which is bonded to the printed circuit board surface using liquid circuit board epoxy.

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

Note
This method uses replacement edge contacts that are fabricated from copper foil. They are available in hundreds of sizes and shapes and are generally supplied either plain copper, solder plated or nickel and gold plated. If a special size or shape is needed it can be custom fabricated.

 
Damaged edge contact needs replacement
Damaged Edge Contact
IPC Acceptability References
IPC-A-600 2.0 Externally Observable Characteristics
IPC-A-610 10.0 Laminate Conditions

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
IPC7721 4.6.1 Edge Contact Repair, Epoxy Method

Tools and Materials
Circuit Frames, Edge Contacts - Replacement circuits with a dry-film adhesive backing for conductor repair.
Circuit Bond Pack - Clear, superior strength epoxy in two-compartment plastic package.
Cleaner - General purpose cleaner for removing contamination.
File - High carbon steel needle file perfect for all kinds of detail work.
High Temperature Tape Discs - High temperature polyimide tape discs, .50" diameter.
Knife with #16 Blades - A must-have tool for precise cutting, scraping and trimming.
Microscope - It is a challenge to undertake precision repair without a good microscope.
Oven - General purpose oven for drying, baking and curing epoxies.
Scraper - Hardened stainless steel tip for scraping solder mask and removing defects.
Soldering Iron, Solder and Flux - A well maintained soldering iron is a must at every tech bench.
Tweezer, Point Tip - Fine point tweezers for precision work.
Wipes - Nonabrasive, low-linting wipes for cleanup.

4.6.1 Edge Contact Repair, Epoxy Method

Printed Board Type: R/F/W/C  |  Skill Level: Advanced  |  Conformance Level: Medium  |  Rev.: C  |  Rev. Date: Jul 7, 2000

Remove defective edge contact and solder mask

Fig. 1: Remove the defective edge
contact and remove solder mask
from the connecting circuit.


1.  Clean the area.
 
2.  Remove the defective edge contact and a short length of the connecting circuit. Heat from a soldering iron will allow the old contact to be removed more easily. (See Figure 1).
   
3.  Use the knife and scrape off any epoxy residue, contamination or burned material from the board surface.
 
  Caution
Abrasion operations can generate electrostatic charges.
 
4.  Scrape off any solder mask or coating from the connecting circuit. (See Figure 1).
Select replacement contact that matches missing contact

Fig. 2: Select replacement contact that matches the missing contact.


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.  The area for the new edge contact on the board surface must be smooth and flat. If internal fibers of the board are exposed or deep scratches exist in the surface they should be repaired. Refer to appropriate procedure.
   
8.  Select a new edge contact that most closely matches the edge contact to be replaced from the Edge Contact Circuit Frames shown below or choose one from the replacement edge contacts which are included with your purchase of the Gold Contact Repair Kit. (See Figure 2).
Cut out new edge contact

Fig. 3: Cut out new edge contact.


9.  Cut out and trim the new edge contact. Cut out from the plated side. Cut the length to provide the maximum allowable joint if lap soldering. Minimum 2 times the circuit width. Leave the new edge contact extra long. The excess material will be trimmed after curing. (See Figure 3).
   
  Note
The new replacement land may be trimmed from copper sheet.
   
10. Mix the epoxy and apply a small amount to the surface where the new contact will be placed.
Place new edge contact

Fig. 4: Place new edge contact
in place using High Temperature
Tape.


11. Place a piece of High Temperature Tape over the top surface of the new edge contact. Position the new edge contact on the circuit board surface using the tape to aid in alignment. (See Figure 4).
   
  Note
Allow the edge contact to overhang the edge of the circuit board. Leave the tape in place during the bonding cycle.
   
12. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
   
  Caution
Some components may be sensitive to high temperature.
   
13. After the epoxy has cured, remove the High Temperature Tape used for alignment. Carefully clean and inspect the new pad for proper alignment.
   
  Note
Additional epoxy can be applied around the perimeter of the new edge contact to provide additional bond strength
   
14. If the new edge contact has a connecting circuit apply a small amount of liquid flux to the lap solder joint connection area and solder the circuit from the new edge contact to the circuit on the circuit board surface. Use minimal flux and solder to ensure a reliable connection. High Temperature Tape may be placed over the top of the new edge contact to prevent excess solder overflow.
   
  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.
   
15. Remove the Kapton tape and clean the area.
   
File new edge contact to blend with existing bevel

Fig. 5: File overhanging piece of
new edge contact to blend with existing bevel.


16. Trim the extending edge of the new edge contact with a file. File parallel to the beveled edge until the excess material has been removed. (See Figure 5).
   
17. If sealing the lap solder joint connection is required, mix epoxy and coat the lap solder joint connections. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
   
18. If plating is required refer to appropriate procedure.
   
19. Apply surface coating to match prior coating as required.
Edge contact repair completed

Fig. 6: Gold contact repair
completed.
Evaluation
   
1.  Visual examination, measurement of new pad width and spacing.
   
2.  Electrical continuity measurement.


Circuit Frame Material Specifications

Overall Frame Size: 2.25" x 1.50" (57 mm x 38 mm)
Base Material: Rolled annealed copper foil .0014" (.036 mm) thick.
Adhesive Backing: B-staged modified acrylic film adhesive .002" (.051 mm) thick.
Bonding Temperature: 475°F +/- 25°F (246°C +/- 14°C)
Bonding Time: 30 seconds
Peel Strength: Minimum 8 lbs/inch (1.43 kg/cm) after cure to FR-4 material.
Shelf Life: 1 year minimum. Each Circuit Frame package is stamped with the expiration date.
Shelf-Life items may not be returned for credit.
Plating Option - Nickel/Gold:     .000050" (.00127 mm) Gold over .000100" (.00254 mm) Nickel


Special Order. Usually ships within 3 business days. Ships From: Haverhill, MA, USA.

How to purchase. For customer service call 1-519-651-3060.

Edge Contact Circuit Frames          Minimum order requirement $50 plus shipping.

Image Description                                                            View cart Part Number
CC035080AG Contacts .035" x .080" Circuit Frame CC035080AG

Contacts .035" x .080" (.889mm x 2.032mm)

Plating: Nickel/Gold

Enlarge
CC035080AG

US $149.00

 
CC038255AG Contacts .038" x .250" Circuit Frame CC038255AG

Contacts .038" x .250" (.965mm x 6.350mm)

Plating: Nickel/Gold

Enlarge
CC038255AG

US $149.00

 
CC050060AG Contacts .050"/.060" Circuit Frame CC050060AG

Contacts .050"/.060" (1.27mm/1.52mm)

Plating: Nickel/Gold

Enlarge
CC050060AG

US $149.00

 
CC050300AG Contacts .050" x .300" Circuit Frame CC050300AG

Contacts .050" x .300" (1.27mm x 7.62mm)

Plating: Nickel/Gold

Enlarge
CC050300AG

US $149.00

 
CC070080AG Contacts .070"/.080" Circuit Frame CC070080AG

Contacts .070"/.080" (1.78mm/2.03mm)

Plating: Nickel/Gold

Enlarge
CC070080AG

US $149.00

 
CC076190AG Contacts .076" x .190" Circuit Frame CC076190AG

Contacts .076" x .190" (1.93mm x 4.83mm)

Plating: Nickel/Gold

Enlarge
CC076190AG

US $149.00

 
CC085360AG Contacts .085" x .360" Circuit Frame CC085360AG

Contacts .085" x .360" (2.16mm x 9.14mm)

Plating: Nickel/Gold

Enlarge
CC085360AG

US $149.00

 
CC090300AG Contacts .090" x .300" Circuit Frame CC090300AG

Contacts .090" x .300" (2.28mm x 7.62mm)

Plating: Nickel/Gold

Enlarge
CC090300AG

US $149.00

 
Liquid circuit board epoxy Circuit Bond Pack  MSDS, 115-3302

Clear, low viscosity, superior strength epoxy, precisely measured out into a two-compartment plastic package so it's easy to use and there's no measuring (2 gram). Shelf life: 6 months minimum.

Enlarge
115-3302

$12.95 each

 
File 115-3132 File

High carbon steel needle file perfect for all kinds of detail work. File can be used to put the perfectly beveled edge on replacement gold edge contacts.

Enlarge
115-3132

$9.95 each

 
High Temperature Tape Discs 235-3050 High Temperature Tape Discs, .50" Diameter, 235-3050

High temperature tape discs are made of polyimide film with 1.5 mil of silicone adhesive that will not leave any residue. They can withstand temperatures of up to 500°F (260°C).
235-3050

US $5.95 pkg/60

 
Knife 355-0614 Knife with #16 Blades, 355-0614

A must-have tool for precise cutting, scraping and trimming. Includes five #16 blades.


Enlarge
355-0614

$9.95 each

 
Scraper 335-3197 Scraper, 335-3197

Hardened stainless steel tip for scraping solder mask and removing defects.



Enlarge
335-3197

$9.95 each

 
Tweezer, Point Tip 335-5185 Tweezer, Point Tip, 335-5185

Fine point tweezers are perfect for precision work.



Enlarge
335-5185

$9.95 each

 

Products above ship direct from manufacturer and are special order/non-returnable. Will ship within 3 business days.



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Links to Related Products


Circuit Frames used to replace pads, lands and conductors   Circuit Frames
Circuit Frames allow you to replace damaged surface mount pads, lands and conductors without the mess of liquid epoxy, with a bond strength equal to the original, in just a few minutes. Circuit Frames come in a wide variety of shapes and sizes, all with a dry-film adhesive backing, activated and cured with heat and pressure. Trim out the circuit you need and bond it to the circuit board surface using a Bonding Iron or Circuit Bonding System with the appropriate Bonding Tip.


Gold Contact Repair Kit used to repair damaged gold edge contacts   Gold Contact Repair Kit 201-1120
Repairing gold edge contacts on circuit boards is delicate work, but this circuit board repair kit helps make the process easier and more reliable. You simply select the correct size and shape of gold plated contact from the circuit frames which are included in this kit and bond it in place. The replacement circuits have a dry film, adhesive backing that is activated and cured with heat and pressure. This gold contact repair method restores your boards to their original level of performance and reliability.



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