When your design requires a change or modification at a BGA site, using a standard jumper wire is normally not an option. Jumper wires are simply too large to fit under a BGA component.
This ingenious modification procedure, developed at Circuit Technology Center, uses flat copper ribbon thin enough to fit reliably between the underside of the BGA component and the circuit board surface.
Here is the procedure.
Step 1. If needed, we first remove the BGA component. We cut the connection to the via using a precision drill system or milling machine.
Step 2. We remove the appropriate BGA pad and machine a shallow channel into the solder mask surface.
Step 3. We bond a new BGA pad in place. The new BGA pad has a dry-film adhesive backing and is bonded using a special bonding iron that applies heat and pressure to cure the adhesive film. The dry-film adhesive process eliminates the need to use messy liquid epoxy to bond the new pad to the circuit board surface.
Step 4. We solder a copper circuit track to the tail extending from the new BGA pad. Circuit tracks are thin, ribbon-shaped copper wires with a very low profile so are perfectly designed for this unique application.
Step 5. We solder a standard jumper wire to the end of the circuit track extending beyond the BGA component body footprint. The opposite end of the jumper wire is terminated as required. We then overcoat the entire circuit track to provide the proper insulation before installing the replacement BGA component.
This is an expert-level rework procedure, but one that has been completed successfully thousands of times by the experienced technicians at Circuit Technology Center. Contact Circuit Technology Center for more information.