Circuit Board Repair Guide > Conductor Repair Procedures > 4.7.4 Surface Mount, BGA Pad with Integral Via Repair

Surface Mount, BGA Pad with Integral Via Repair

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

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.
 
Damaged BGA pad needs replacement
Damaged BGA Pad

Related Procedure References
CTC1.0Foreword - Circuit Board Repair Guide
CTC2.1Handling Electronic Assemblies
CTC2.2.1How to Clean a Circuit Board
CTC2.2.2Cleaning Circuit Boards, Aqueous Batch Process
CTC2.5Baking and Preheating of Printed Circuit Boards
CTC2.7Epoxy 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.
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.

4.7.4 Surface Mount, BGA Pad with Integral Via Repair

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

Remove defective pad and prepare connecting via

Figure 1: Remove the defective pad
and prepare connecting via.


1. 
Clean the area.
 
2.  Carefully remove the defective pad to avoid damaging the integral via.
  
3. 
Use a knife and scrape off any epoxy residue, contamination or burned material from the board surface.
 
4.  Scrape off any residue from the exposed via. (See Figure 1).
Trough recessed into board

Figure 2: Trough or gully recessed
into board to permit circuit routing to
be level with board surface.


5.  Clean the area.
  
6. 
Apply a small amount of liquid flux to the via connection on the board surface. Using the appropriate size solder braid remove solder from the via. 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. In this procedure a trough or gully must be recessed into the board from the via location to the outside edge of the affected pad. This permits the via to pad connecting circuit adequate space for routing without interfering with the pressing of the new BGA pad. (See Figure 2).


 

Select replacement pad that matches missing pad

Figure 3: 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 3).
  
 
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 bonding film from pad

Figure 4: 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 new pad. In order to ensure that the final pressed pad lays flat, it may be necessary to remove the film from the whole length of the connecting circuit up to the pad itself. (See Figure 4).
  
 
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 fit into via

Figure 5: Connecting circuit is fit
into via.
11.
Turning the pad upside down, place the pad on the board so that the connecting circuit can be fit into the via. Ensure the connecting circuit is running over the previously cut trough. (See Figure 5). The connecting circuit of the new BGA pad will be inserted into the integral via hole of the original BGA pad.
  
12. Insert the connecting circuit into the via and carefully flux the connection area.
  
13. Solder the connecting circuit into the via.
  
14.
Lay the connecting circuit into the bottom of the trough. If required, apply a securing film of high strength epoxy over the connecting circuit to secure in place and provide a flat surface on which to press the new BGA pad.
  
15.
Fold over the new BGA pad 180 degrees and place the new pad into position on the circuit board surface using high temperature tape to help in alignment.
  
Bond new pad using a Bonding System

Figure 6: Bond the new pad
using a Bonding System or
Bonding Iron with appropriate
Bonding Tip.


16.
Select a bonding tip with a shape to match the shape of the new pad. See bonding tip chart below. (See Figure 6).
  
 
Note
The tip used for bonding should be as small as possible but should completely cover the entire surface of the new pad.
  
17.
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 pad. Apply pressure as recommended in the manual of the repair system or repair kit for 5 seconds to tack the new pad in place. Carefully peel off the tape.
  
 Caution
E
xcessive bonding pressure may cause measling in the circuit board surface or may cause the new pad to slide out of position.
BGA pad repair completed

Figure 7: Completed repair.
18.
Gently place the bonding tip directly onto the new pad. Apply pressure as recommended in the manual of the repair system or repair kit for an additional 30 seconds to fully bond the pad. After the bonding cycle remove the tape used for alignment. The new pad is fully cured. Carefully clean the area and inspect the new pad for proper alignment. (See Figure 7).
  
19.
Additional liquid circuit board 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.
  
20. 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.
 

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:475F +/- 25F (246C +/- 14C)
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 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. Ship within 3 business days. For customer service call us at 1-519-651-3060. How to purchase.

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

ImageDescription                                                            View cartPart 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 $39.00

 
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 $39.00

 
CS020020AS BGA Pads .020" DiameterCircuit Frame CS020020AS

BGA Pads .020" (.508mm) Diameter

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115-2201
CS020020AS

US $39.00

 
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 $39.00

 
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 $39.00

 
CS026026AG BGA Pads .026" DiameterCircuit Frame CS026026AG

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

Plating: Nickel/Gold

Enlarge
CS026026AG

US $129.00

 
CS051063AS BGA Pads .051"/.063" DiameterCircuit Frame CS051063AS

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

Plating: Bright Tin

Enlarge        Recommended Bonding Tip: 115-2204
CS051063AS

US $39.00

 
CS092092AS BGA Pads .092" DiameterCircuit Frame CS092092AS

BGA Pads .092" (2.33mm) Diameter

Plating: Bright Tin

Enlarge
CS092092AS

US $39.00

 
Liquid circuit board epoxyCircuit 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.

Enlarge
115-3302

$10.95 each

 
High Temperature Tape Discs 235-3050High 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 500F (260C).
235-3050

US $5.95 pkg/60

 
Knife 355-0614Knife 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 335-3197Scraper, 335-3197

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



Enlarge
335-3197

$9.95 each

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

Fine point tweezers are perfect for precision work.



Enlarge
335-5185

$5.95 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.

ImageDescription                                                            View cartPart Number
Bonding Iron 115-3102Bonding 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 $79.00

 
Bonding Iron 115-3103Bonding 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 $125.00

 

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

 

115-2314 Large Rectangle Tip .060" x .500"
Bonding Tip 115-2314

.060" x .500" (1.52mm x 12.70mm)

Large Rectangle

115-2314

US $45.00

 

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

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

Large 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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4.7.4 Surface Mount, BGA Pad with Integral Via Repair