Circuit Board Repair Guide > Conductor Repair Procedures > 4.5.1 How to Replace Damaged Lands Using Liquid Epoxy

How to Replace Damaged Lands Using Liquid Epoxy

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 repair procedure is used to replace damaged and lifted lands using liquid circuit board epoxy. The damaged lands are replaced with new lands.

Caution
This method is used to replace a damaged or missing land, but the new land will not have an intermetallic connection to the remaining plated hole. The solder joint of the replaced component will restore the electrical connection.
 
Damaged land needs replacement
Damaged Land
Caution
It is essential that the board surface be smooth and flat. If the base board is damaged see appropriate procedure.

Note
This method uses new lands that are fabricated from copper foil. They are available in hundreds of sizes and shapes and are generally supplied solder plated. If a special size or shape is needed it can be custom fabricated.

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 4.5.1 Land Repair, Epoxy Method

Tools and Materials
Circuit Frames, Lands - 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.
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.

4.5.1 Land Repair, Epoxy Method

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

Remove defective land and solder mask

Figure 1: Remove the defective
land and remove solder mask
from the connecting circuit.


1.  Clean the area.
 
2. Remove the defective land and a short length of the connecting circuit if any.
(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 land

Figure 2: Select a replacement
land that matches the missing
land.


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 pad on the board surface must be smooth and flat. If internal fibers of the board are exposed or if there are deep scratches in the surface they should be repaired. Refer to appropriate procedure.
   
8.  Select a replacement land that most closely matches the land to be replaced from the Land Circuit Frames shown below. (See Figure 2).
Cut out replacement land

Figure 3: Cut out the replacement land.


9.  Cut out and trim the new land. Cut the length to provide the maximum allowable circuit overlap for soldering. Minimum 2 times the circuit width. (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 land will be placed.
Place new land

Figure 4: Place the new land in
place using High Temperature
Tape.


11. Place a piece of High Temperature Tape over the top surface of the land. Place the new land into position on the circuit board surface using the tape to aid in alignment. (See Figure 4).
   
12. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
   
13. After the epoxy has cured, remove the High Temperature Tape used for the alignment. Carefully clean the area and inspect the new land for proper alignment.
   
14. If the new land 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 land to the circuit on the circuit board surface. Use minimal flux and solder to ensure a reliable connection. Tape may be placed over the top of the new land to prevent excess solder.
   
  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 tape and clean the area.
   
16. Mix the epoxy and coat the lap solder joint connections. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
   
  Note
Additional epoxy can be applied around the perimeter of the new land to provide additional bond strength.
   
  Caution
Some components may be sensitive to high temperature.
   
17. Carefully remove any excess epoxy inside the plated hole using a ball mill or drill bit. Turn the ball mill or drill bit by hand to prevent damage to the wall of the plated through hole.
   
18. Install the proper component and solder in place.
   
  Note
This method is used to replace a damaged or missing land, but the new land will not have an inter-metallic connection to the remaining plated hole. The solder joint of the replaced component will restore the integrity of the electrical connection or an eyelet or buss wire may be used. See Plated Hole Repair Procedures.
   
19. Apply surface coating to match prior coating as required.
   
Land repair completed

Figure 5: Land repair completed.
Evaluation
   
1.  Visual examination.
   
2.  Measurement of new pad width and spacing.
   
3.  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 - Bright Tin:     .0001" (.0025 mm) Bright Tin (Lead Free)


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

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

Land Circuit Frames                           Minimum order requirement $50 plus shipping.

Image Description                                                            View cart Part Number
CP050060AS Lands .050"/.060" Circuit Frame CP050060AS

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

Plating: Bright Tin

Enlarge
CP050060AS

US $44.00

 
CP067267AS Lands .067" x .267" Circuit Frame CP067267AS

Lands .067" x .267" (1.70mm x 6.78mm)

Plating: Bright Tin

Enlarge
CP067267AS

US $44.00

 
CP070080AS Lands .070"/.080" Circuit Frame CP070080AS

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

Plating: Bright Tin

Enlarge
CP070080AS

US $44.00

 
CP090100AS Lands .090"/.100" diameter Circuit Frame CP090100AS

Lands .090"/.100" (2.286mm/2.540mm) Diameter

Plating: Bright Tin

Enlarge
CP090100AS

US $44.00

 
CP090100BS Lands 0.090" x 0.100" Circuit Frame CP090100BS

Lands .090" x .100" (2.286mm x 2.540mm)

Plating: Bright Tin

Enlarge
CP090100BS

US $44.00

 
CP140210AS Lands .140"ID x .210"OD Circuit Frame CP140210AS

Lands .210" (5.334mm) Diameter

Plating: Bright Tin

Enlarge
CP140210AS

US $44.00

 
CP156097AS Lands .156"OD x .097"ID Circuit Frame CP156097AS

Lands .156" (3.962mm) Diameter

Plating: Bright Tin

Enlarge
CP156097AS

US $44.00

 
CP250125AS Lands .250"OD x .125"ID Circuit Frame CP250125AS

Lands .250" (6.350mm) Diameter

Plating: Bright Tin

Enlarge
CP250125AS

US $44.00

 
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

 
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.


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.



Copyright and Disclaimer Notice Phone: 1-519-651-3060             Ships From: Haverhill, MA 01835 USA

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