Circuit Board Repair Guide > Conductor Repair Procedures > 4.7.1 How to Repair Damaged Surface Mount Pads Using Liquid Epoxy

How to Repair Damaged Surface Mount Pads 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 circuit board repair procedure is used to replace damaged surface mount pads with commercially available replacement pads 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 commercially available replacement surface mount pads. The new pads 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.
 
Damaged surface mount pad needs repair
Damaged Surface Mount Pad

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 4.7.1 Surface Mount Pad Repair, Epoxy Method

Tools and Materials
Circuit Frames, SMT Pads - 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.

4.7.1 Surface Mount Pad Repair, Epoxy Method

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

Remove defective pad and solder mask

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


1.  Clean the area.
 
2.  Remove the defective pad and a short length of the connecting circuit. (See Figure 1).
   
3.  Use 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 surface mount pad

Figure 2: Select a commercially
available replacement pad that
matches the missing pad.


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 SMT pad that most closely matches the SMT pad to be replaced from the SMT Pad Circuit Frames shown below or choose one from the large variety of replacement circuits which are included when you purchase the Professional Repair Kit. If a special size or shape is needed it can be custom fabricated. (See Figure 2).
Cut out new surface mount pad

Figure 3: Cut out the new SMT pad.


9.  Cut out and trim the new pad. 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 surface mount pad may be trimmed from copper sheet.
   
10. Mix the epoxy and apply a small amount to the surface where the new pad will be placed.
Place new surface mount pad

Figure 4: Place new SMT pad in
place using High Temperature
Tape.


11. Place a piece of High Temperature Tape over the top surface of the new pad. Place the new pad into position on the circuit board surface using the tape to help in alignment. (See Figure 4).
   
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 tape used for alignment. Carefully clean the area and inspect the new pad for proper alignment.
   
14. If the new pad 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 pad 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 pad 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. Mix epoxy and coat the lap solder joint connections. Cure the epoxy per the manufacturer's recommended instructions.
   
  Note
Additional epoxy can be applied around the perimeter of the new pad to provide additional bond strength
   
16. Apply surface coating to match prior coating as required.
   
Surface mount pad repair completed

Figure 5: Surface mount pad 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.

SMT Pad Circuit Frames                   Minimum order requirement $50 plus shipping.

Image Description                                                            View cart Part Number
CS004085AS SMT Pads .004" x .085" Circuit Frame CS004085AS

SMT Pads .004" x .085" (.101mm x 2.159mm)

Plating: Bright Tin

Enlarge
CS004085AS

US $44.00

 
CS011061AS SMT Pads .011" x .061" Circuit Frame CS011061AS

SMT Pads .011" x .061" (.279mm x 1.549mm)

Plating: Bright Tin

Enlarge
CS011061AS

US $44.00

 
CS012060AS SMT Pads .012" x .060" Circuit Frame CS012060AS

SMT Pads .012" x .060" (.304mm x 1.524mm)

Plating: Bright Tin

Enlarge
CS012060AS

US $44.00

 
CS012100AS SMT Pads .012" x .100" Circuit Frame CS012100AS

SMT Pads .012" x .100" (.304mm x 2.540mm)

Plating: Bright Tin

Enlarge
CS012100AS

US $44.00

 
CS020028AS SMT Pads .020" x .028" Circuit Frame CS020028AS

SMT Pads .020" x .028" (.508mm x .711mm)

Plating: Bright Tin

Enlarge
CS020028AS

US $44.00

 
CS025080AS SMT Pads .025" x .080" Circuit Frame CS025080AS

SMT Pads .025" x .080" (.635mm x 2.032mm)

Plating: Bright Tin

Enlarge
CS025080AS

US $44.00

 
CS025080BS SMT Pads .025" x .080" Circuit Frame CS025080BS

SMT Pads .025" x .080" (.635mm x 2.032mm)

Plating: Bright Tin

Enlarge
CS025080BS

US $44.00

 
CS028185AS SMT Pads .028" x .185" Circuit Frame CS028185AS

SMT Pads .028" x .185" (.711mm x 4.699mm)

Plating: Bright Tin

Enlarge
CS028185AS

US $44.00

 
CS030055AS SMT Pads .030" x .055" Circuit Frame CS030055AS

SMT Pads .030" x .055" (.762mm x 1.397mm)

Plating: Bright Tin

Enlarge
CS030055AS

US $44.00

 
CS034030AS SMT Pads .034" x .030" Circuit Frame CS034030AS

SMT Pads .034" x .030" (.863mm x .762mm)

Plating: Bright Tin

Enlarge
CS034030AS

US $44.00

 
CS038090AS SMT Pads .038" x .090" Circuit Frame CS038090AS

SMT Pads .038" x .090" (.965mm x 2.286mm)

Plating: Bright Tin

Enlarge
CS038090AS

US $44.00

 
CS039039AS SMT Pads .039" x .039" Circuit Frame CS039039AS

SMT Pads .039" x .039" (.991mm x .991mm)

Plating: Bright Tin

Enlarge
CS039039AS

US $44.00

 
CS040070AS SMT Pads .040" x .070" Circuit Frame CS040070AS

SMT Pads .040" x .070" (1.016mm x 1.778mm)

Plating: Bright Tin

Enlarge
CS040070AS

US $44.00

 
CS040110AS SMT Pads .040" x .110" Circuit Frame CS040110AS

SMT Pads .040" x .110" (1.016mm x 2.794mm)

Plating: Bright Tin

Enlarge
CS040110AS

US $44.00

 
CS045110AS SMT Pads .045" x .110" Circuit Frame CS045110AS

SMT Pads .045" x .110" (1.143mm x 2.794mm)

Plating: Bright Tin

Enlarge
CS045110AS

US $44.00

 
CS046106AS SMT Pads .046" x .106" Circuit Frame CS046106AS

SMT Pads .046" x .106" (1.168mm x 2.692mm)

Plating: Bright Tin

Enlarge
CS046106AS

US $44.00

 
CS048068AS SMT Pads .048" x .068" Circuit Frame CS048068AS

SMT Pads .048" x .068" (1.219mm x 1.727mm)

Plating: Bright Tin

Enlarge
CS048068AS

US $44.00

 
CS050050AS SMT Pads .050" x .050" Circuit Frame CS050050AS

SMT Pads .050" x .050" (1.270mm x 1.270mm)

Plating: Bright Tin

Enlarge
CS050050AS

US $44.00

 
CS051087AS SMT Pads .051" x .087" Circuit Frame CS051087AS

SMT Pads .051" x .087" (1.295mm x 2.209mm)

Plating: Bright Tin

Enlarge
CS051087AS

US $44.00

 
CS060080AS SMT Pads .060" x .080" Circuit Frame CS060080AS

SMT Pads .060" x .080" (1.524mm x 2.032mm)

Plating: Bright Tin

Enlarge
CS060080AS

US $44.00

 
CS065055AS SMT Pads .065" x .055" Circuit Frame CS065055AS

SMT Pads .065" x .055" (1.651mm x 1.397mm)

Plating: Bright Tin

Enlarge
CS065055AS

US $44.00

 
CS065095AS SMT Pads Frame .065" x .095" Circuit Frame CS065095AS

SMT Pads .065" x .095" (1.651mm x 2.413mm)

Plating: Bright Tin

Enlarge
CS065095AS

US $44.00

 
CS067173AS SMT Pads .067" x .173" Circuit Frame CS067173AS

SMT Pads .067" x .173" (1.701mm x 4.394mm)

Plating: Bright Tin

Enlarge
CS067173AS

US $44.00

 
CS071106AS SMT Pads .071" x .106" Circuit Frame CS071106AS

SMT Pads .071" x .106" (1.803mm x 2.692mm)

Plating: Bright Tin

Enlarge
CS071106AS

US $44.00

 
CS090100AS SMT Pads .090" x .100" Circuit Frame CS090100AS

SMT Pads .090" x .100" (2.28mm x 2.54mm)

Plating: Bright Tin

Enlarge
CS090100AS

US $44.00

 
CS095000AS SMT Pads .095" Diameter Circuit Frame CS095000AS

SMT Pads .095" (2.41mm) Diameter

Plating: Bright Tin

Enlarge
CS095000AS

US $44.00

 
CS095095AS SMT Pads .095" x .095" Circuit Frame CS095095AS

SMT Pads .095" x .095" (2.413mm x 2.413mm)

Plating: Bright Tin

Enlarge
CS095095AS

US $44.00

 
CS130177AS SMT Pads .130" x .177" Circuit Frame CS130177AS

SMT Pads .130" x .177" (3.302mm x 4.496mm)

Plating: Bright Tin

Enlarge
CS130177AS

US $44.00

 
CSV002AS SMT Pads .100" x .100" Circuit Frame CSV002AS

SMT Pads .100" x .100" (2.54mm x 2.54mm)

Plating: Bright Tin

Enlarge
CSV002AS

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


Professional Repair Kit used to repair damaged circuit boards   Professional Repair Kit 201-2100
This circuit board repair kit includes everything needed for a wide range of circuit board repair needs. The Professional Repair Kit is designed to be used for the following applications: surface mount and BGA pad repair, circuit and land repair, plated hole repair, gold edge contact repair, solder mask and base board repair. This is the most popular circuit board repair kit we sell.


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.



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

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