Circuit Board Repair Guide > Conductor Repair Procedures > 4.7.5 Surface Mount, BGA Pad with Integral Via Repair Circuit Extension Method

Surface Mount, BGA Pad with Integral Via Repair Circuit Extension Method

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 BGA pads with new dry film adhesive backed pads. The new pads are bonded to the printed circuit board surface using a specially designed circuit bonding system or bonding iron. Electrical connection is made to a via circuit which is originally manufactured integral to the pads.

Note
This procedure uses replacement BGA pads. The new pads are fabricated from copper foil. They are available in a variety of sizes and shapes and are generally supplied solder plated. If a special size or shape is needed they can be custom fabricated.

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

Tools and Materials
Bonding Iron, 120 VAC - Delivers the optimal heat for curing adhesive bonding film.  Bonding Tips sold separately.
Bonding Tips - Used to cure adhesive backed circuit frames for pad, land and contact repair.
Circuit Bonding System  (optional) - System for applying heat and pressure to cure adhesive bonding film.
Circuit Frames, BGA 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.
Micro Drill System - Versatile power tool for milling, drilling, grinding, cutting and sanding circuit boards.
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.

4.7.5 Surface Mount, BGA Pad with Integral Via Repair Circuit Extension Method

Printed Board Type: R/F/C  |  Skill Level: Expert  |  Conformance Level: High  |  Rev.: B  |  Rev. Date: May 8, 2001

Remove damaged BGA pad with integral via

Figure 1: Remove the damaged pad
with integral via.


  Note
Prior to proceeding determine whether this procedure or 4-7-4 Surface Mount, BGA Pad with Integral Via Repair, is the appropriate method. This method is best used when a connecting circuit or plane clearly runs from the integral via and is close to the board's affected surface to permit exposure of the circuit for the repair connection.
   
1.  Clean the area.
 
2.  Carefully remove the defective pad to avoid damaging the integral via (See Figure 1).
   
3.  Use knife and scrape off any epoxy residue, contamination or burned material from the board surface.
 
Micro Drill System used for milling, drilling, grinding, cutting and sanding circuit boards

Figure 2: Micro Drill System


4.  Using a Micro Drill System (See Figure 2) and the appropriate ball mill down to the connecting circuit, exposing the copper surface of the etch (See Figure 3). Be careful not to cut through the circuit.

Expose copper circuit

Figure 3: Using a Micro Drill expose
the copper circuit by recessing a
trough or gully.


5.  Clean the area
Tin circuit with solder

Figure 4: Tin the circuit with solder.


6.  Apply a small amount of liquid flux to the circuit connection now exposed beneath the surface of the board. Tin the circuit with solder (See Figure 4 ). Clean the area
   
7.  In general, 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.
Select replacement pad that matches missing pad

Figure 5: Select a replacement pad
that matches the missing pad.


8.  Select a replacement BGA pad that most closely matches the surface mount pad to be replaced. If a special size or shape is needed they can be custom fabricated. (See Figure 5). Ensure the selected pads attached circuit matches the width and thickness of the circuit to be replaced. Trim the width approximately as needed. The circuit should overlap the existing circuit a minimum of 2 times the circuit width.
  Note
New BGA pads are fabricated from copper foil. The foil is plated on the top side with solder, and an adhesive bonding film is applied to the bottom side.
Scrape off adhesive from new pad

Figure 6: Scrape off the adhesive bonding film from the solder joint connection area on the back of
new pad.


9.  Before trimming out the new pad, carefully scrape off the adhesive bonding film from the solder joint connection area on the back of the replacement circuit portion of the new pad. In order to ensure that the final pressed pad lays flat (and the new circuit is properly connected to the exposed board circuit), it may be necessary to remove the film from the whole length of the connecting circuit up to the pad itself. (See Figure 6).
   
  Caution
When handling the replacement pad, avoid touching the epoxy backing with your fingers or other materials that may contaminate the surface and reduce the bond strength.
   
10. Cut out and trim the new pad. Cut out from the plated side.
Connecting circuit connected to exposed and tinned circuit

Figure 7: Connecting circuit
connected to the exposed and
tinned circuit.


11. Place the pad on the board so that the connecting circuit can be fit into the trough containing the board's tinned circuit (See Figure 7).
Bond new BGA pad using Bonding System

Figure 8: Bond the new pad
using a Bonding System or
Bonding Iron with appropriate
Bonding Tip.


12. Select a bonding tip with a shape to match the shape of the new pad. See bonding tip chart below. (See Figure 8).
   
  Note
The tip used for bonding should be as small as possible but should completely cover the entire surface of the new pad.
   
13. Position the circuit board so that it is flat and stable. Gently place the bonding tip directly onto the new pad. Apply pressure as recommended in the manual of the repair system or circuit board repair kit for 30 seconds to fully bond the pad. The new pad is fully cured. Carefully clean the area and inspect the new pad for proper alignment.
   
  Caution
Excessive bonding pressure may cause measling in the circuit board surface or may cause the new pad to slide out of position.
   
14. Apply flux to the overlapping connecting circuit in the bottom of the trough. Solder in place. Clean the area.
   
  Note
The circuit board may be preheated prior to filling the area with epoxy. A preheated circuit board will allow the epoxy to easily flow and level out. Epoxy applied to an unheated circuit board may settle below the circuit board surface as the epoxy cures.
   
15. Mix epoxy. If desired, add color agent to the mixed epoxy to match the circuit board color.
   
16. Coat the top and sides of the replaced circuit with epoxy. The epoxy bonds the new circuit to the base board material and insulates the circuit. Continue adding liquid circuit board epoxy up to the top surface of the circuit board.
   
  Note
A very slight overfill of epoxy may be desired to allow for shrinkage when the epoxy cures. Additionally, in order to allow the circuits appearance to match the board, it may be necessary to mask the circuit prior to filling the excavated area.
   
17. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
   
  Caution
Some components may be sensitive to high temperature.
   
18. Additional epoxy can be applied around the perimeter of the new pad to provide additional bond strength. Mix epoxy. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling. Use the maximum recommended heat cycle to ensure the highest strength bond. BGA pads are routinely subjected to one or more reflow cycles.
   
  Caution
Some components may be sensitive to high temperature.
   
Completed integral via repair

Figure 9: Completed repair.

19. Apply surface coating to match prior coating as required. (See Figure 9)
 
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)
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.

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

Image Description                                                            View cart Part Number
CS010012AS BGA Pads .010"/.012" Circuit Frame CS010012AS

BGA Pads .010"/.012" (.254mm/.305mm) Diameter

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115‐2201
CS010012AS

US $44.00

 
CS015020AS BGA Pads .015" x .020" Circuit Frame CS015020AS

BGA Pads .015"/.020" (.381mm/.508mm) Diameter

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115‐2201
CS015020AS

US $44.00

 
CS020020AS BGA Pads .020" Diameter Circuit Frame CS020020AS

BGA Pads .020" (.508mm) Diameter

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115‐2201
CS020020AS

US $44.00

 
CS020025AS BGA Pads .020"/.025" Circuit Frame CS020025AS

BGA Pads .020"/.025" (.508mm/.635mm) Diameter

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115‐2201
CS020025AS

US $44.00

 
CS025035AS BGA Pads .025" x .035" Circuit Frame CS025035AS

BGA Pads .025"/.035" (.635mm/.889mm) Diameter

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115-2205
CS025035AS

US $44.00

 
CS026026AG BGA Pads .026" Diameter Circuit Frame CS026026AG

BGA Pads .026" Dia., .003" Track

Plating: Nickel/Gold

Enlarge
CS026026AG

US $149.00

 
CS051063AS BGA Pads .051"/.063" Diameter Circuit Frame CS051063AS

BGA Pads .051"/.063" (1.295mm/1.600mm) Diameter

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115-2204
CS051063AS

US $44.00

 
CS092092AS BGA Pads .092" Diameter Circuit Frame CS092092AS

BGA Pads .092" (2.33mm) Diameter

Plating: Bright Tin

Enlarge
CS092092AS

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.



 
Bonding Iron and Bonding Tips

Bonding Tips fit into the hand held Bonding Iron (part no. 115-3102 for 120 VAC and part no. 115-3103 for 230 VAC) and the Circuit Bonding System (part no. 115-3118 which includes voltage converter for 120 VAC and 220 VAC). The bottom machined surface of each Bonding Tip is used to apply heat and pressure to bond the adhesive backed replacement pads, edge contacts, and lands to the circuit board surface. All our Bonding Tips are machined from high grade aluminum.

Image Description                                                            View cart Part Number
Bonding Iron 115-3102 Bonding Iron, 120 VAC, 115-3102

The Bonding Iron is set at the optimal temperature for curing the bonding film used to repair damaged surface mount pads, lands, edge contacts and other circuit board patterns. Bonding Tip is not included with purchase of Bonding Iron so remember to also select and purchase a Bonding Tip to match the shape of the new pad or circuit. Enlarge

115-3102

US $109.00

 
Bonding Iron 115-3103 Bonding Iron, 230 VAC, 115-3103

The Bonding Iron is set at the optimal temperature for curing the bonding film used to repair damaged surface mount pads, lands, edge contacts and other circuit board patterns. Bonding Tip is not included with purchase of Bonding Iron so remember to also select and purchase a Bonding Tip to match the shape of the new pad or circuit. Enlarge

115-3103

US $179.00

 

115-2104 Tapered Tip
Bonding Tip 115-2104

Tapered



115-2104

US $45.00

 

115-2201 Circular Tip .025"
Bonding Tip 115-2201

.025" (.635mm) Diameter

Circular

115-2201

US $45.00

 

115-2202 Circular Tip .060"
Bonding Tip 115-2202

.060" (1.52mm) Diameter

Circular

115-2202

US $45.00

 

115-2204 Circular Tip .080"
Bonding Tip 115-2204

.080" (2.03mm) Diameter

Circular

115-2204

US $45.00

 

115-2205 Circular Tip .035"
Bonding Tip 115-2205

.035" (.89mm) Diameter

Circular

115-2205

US $45.00

 

115-2206 Circular Tip .120"
Bonding Tip 115-2206

.120" (3.05mm) Diameter

Circular

115-2206

US $45.00

 

115-2301 Small Rectangle Tip .010" x .080"
Bonding Tip 115-2301

.010" x .080" (.25mm x 2.03mm)

Small Rectangle

115-2301

US $45.00

 

115-2306 Small Rectangle Tip .040" x .060"
Bonding Tip 115-2306

.040" x .060" (1.02mm x 1.52mm)

Small Rectangle

115-2306

US $45.00

 

115-2308 Small Rectangle Tip .045" x .110"
Bonding Tip 115-2308

.045" x .110" (1.14mm x 2.79mm)

Small Rectangle

115-2308

US $45.00

 

115-2310 Small Rectangle Tip .050" x .050"
Bonding Tip 115-2310

.050" x .050" (1.27mm x 1.27mm)

Small

115-2310

US $45.00

 

115-2312 Small Rectangle Tip .060" x .080"
Bonding Tip 115-2312

.060" x .080" (1.52mm x 2.03mm)

Small Rectangle

115-2312

US $45.00

 

115-2316 Small Rectangle Tip .080" x .120"
Bonding Tip 115-2316

.080" x .120" (2.03mm x 3.05mm)

Small Rectangle

115-2316

US $45.00

 

115-2318 Large Rectangle Tip .080" x .500"
Bonding Tip 115-2318

.080" x .500" (2.03mm x 12.70mm)

Large Rectangle

115-2318

US $45.00

 

115-2320 Small Rectangle Tip .095" x 095"
Bonding Tip 115-2320

.095" x .095" (2.41mm x 2.41mm)

Small

115-2320

US $45.00

 

115-2322 Large Rectangle Tip .120" x .500"
Bonding Tip 115-2322

.120" x .500" (3.05mm x 12.70mm)

Large Rectangle

115-2322

US $45.00

 

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



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