Circuit Board Repair Guide > Jumper Wires and Component Modification Procedures > 6.2.1 Using Jumper Wires, BGA Components, Circuit Track Method

Using Jumper Wires, BGA Components, Circuit Track 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 procedure is used to change a circuit path at a BGA site for engineering changes or modifications.

This method requires precision milling equipment and highly trained technicians.

This method is not applicable for "via in pad" applications.

IPC Acceptability References
IPC-A-600 2.0 Externally Observable Characteristics
IPC-A-610 11.0 Discrete Wiring

Related Procedure References
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
CTC 4.2.1 How to Repair a Damaged Conductor Using a Foil Jumper
CTC 4.7.3 How to Repair Damaged BGA Pads Using New Pads and Film Adhesive
CTC 6.1 How to Use Jumper Wires
CTC 9.2.1 Development of a BGA Component Rework Profile Using the Standard Method
CTC 9.2.2 BGA Component Profile Development, Smart Track
CTC 9.3.1 Hot Gas Method for Eutectic Solder Ball BGA Rework
IPC7721 6.2.1 Jumper Wires, BGA Components, Circuit Track Method

Tools and Materials
Bonding Iron
Bonding Tips

Circuit Bonding System
Circuit Frames, BGA Pads      
Circuit Tracks
End Mills
Flux, Liquid      
Heat Lamp
Milling System
Precision Drill System      
Soldering Station      
Tape, Kapton

6.2.1 Jumper Wires, BGA Components, Circuit Track Method

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

Cut connection to via using Precision Drill System

Figure 1: Cut the connection to the via
using a Precision Drill System.

Clean the area.
Remove the BGA component if installed, remove excess solder from the pads, and clean and inspect the site using standard BGA rework equipment.
Cut the short conductor (dog bone) connecting the BGA pad to the connecting via using a Precision Drill System or milling machine and appropriate size end mill. (See Figure 1 and 6).
Remove BGA pad mill channel into solder mask

Figure 2: Remove the BGA pad and mill
a shallow channel into the solder mask

Remove the existing BGA pad. Apply heat from a soldering iron if needed. (See Figure 2).

Bond new BGA pad in place

Figure 3: Bond a new BGA pad in place.

Use a milling machine to mill a shallow groove in the board surface from the BGA pad area to the perimeter of the BGA site. Tight spacing may restrict the width of the channel to 0.25 mm (.010") or less. Use a carbide end mill approximately0.050 mm (.002") wider than the new connecting circuit. (See Figure 3).
Solder copper circuit track to tail from BGA pad

Figure 4: Solder a copper circuit track to
the tail extending from the new BGA pad.

Bond a replacement BGA pad in place using a bonding system. (See Procedure 4.7.3). The new BGA pad must have a tail that will align with the circuit track to be added next. (See Figure 4).
Select a Circuit Track to match the width and thickness of the circuit to be replaced. Cut a length approximately as needed. The Circuit Track should overlap the BGA tail section a minimum of 2 times the circuit width. See Table 1.
Table 1 - Common Circuit Track Sizes

Part No. Thickness Width
115-5204 .002" .004"
115-5206 .002" .006"
115-5208 .002" .008"
115-5210 .002" .010"
115-5312 .003" .120"
115-5315 .003" .015"
115-5520 .005" .020"
115-5530 .005" .030"

Gently abrade the top and bottom of the new Circuit Track with the buffer to remove any oxidation and clean.
If needed, the ends of the Circuit Track may be tinned with solder prior to lap soldering in place.
Position this new Circuit Track along the milled groove. The Circuit Track (PCB Track) should overlap the existing circuit a minimum of 2 times the circuit width. (See Figure 4).
10. Apply a small amount of liquid flux to the overlap joint.
Lap solder the Circuit Track to the BGA tail section using solder and a soldering iron. Make sure the new circuit is properly aligned.
Solder wire to Circuit Track and overcoat with epoxy

Figure 5: Solder a wire to the Circuit
Track and overcoat with epoxy.

Solder one end of a fine gauge wire to the end of the extending circuit. (The opposite end of the wire will be soldered later.) (See Figure 5).
13. Clean the area.
Mix epoxy. If desired, add color agent to the mixed epoxy to match the circuit board color.
Coat the top and sides of the replaced circuit with liquid circuit board epoxy. The epoxy bonds the new circuit to the base board material and insulates the circuit. (See Figure 5).
16. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
Some components may be sensitive to high temperature.

Precision Drill System used to cut connection

Figure 6: Precision Drill System
used to cut the connection from the
BGA pad to the via.

Clean the board as required.
18. Install new BGA per applicable procedures.
Route and terminate the other end of the jumper wire.
1.  Visual examination for alignment and overlap of new circuit.
2.  Visual examination of epoxy coating for texture and color match.
3.  Electrical tests as applicable.

Links to Related Products

Circuit Bonding System bonds surface mount and BGA pads  
Circuit Bonding System 115-3118
The Circuit Bonding System is the best, calibrated system for bonding adhesive film backed circuits and is ideally suited for bonding small patterns including surface mount and BGA pads. This bonding press not only gives the operator better control over the bonding process, but also ensures optimal adhesion and repeatability. Includes a built-in calibration slide to maintain a regulated bonding force depending upon the circuit pattern size and shape. The digital temperature controller maintains a uniform temperature throughout the 30-second bonding cycle.

Bonding Tips
The Bonding Tips fit into the hand held Bonding Iron (part number 115-3102) and the Circuit Bonding System. 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.

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 Track Kit used to repair damaged PCB tracks  
Circuit Track Kit 201-3130
Thanks to Circuit Tracks, it's now easier than ever to repair damaged circuits. Circuit Tracks are rectangular shaped conductors made of 99.9% pure copper. The rectangular ribbons closely conform to the original conductor dimensions. The replacement Circuit Track is bonded in place using a prepackaged epoxy which is included in this kit. The Circuit Track Kit is a great time and labor-saver and an easy solution to repairing missing or damaged circuits and conductors.

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