Reballing

Reballing is the process of restoring a fresh, uniform set of solder balls to the underside of a BGA chip so it can be cleanly placed back onto a hashboard. When an ASIC is removed during repair, or harvested from a donor board, its original solder balls are left deformed, partially stripped, or contaminated. Without a clean ball array, the chip cannot reliably reflow onto the PCB, so reballing is a prerequisite to reusing any BGA chip.

How reballing is done

The technician first removes the chip, then wicks away the remaining old solder and cleans the pads with flux and braid until the underside is flat and bright. A model-specific reballing stencil or jig is aligned to the chip so its apertures sit over each pad. Solder paste or preformed solder balls are then deposited through the stencil and reflowed, leaving a precise grid of identical new balls. The reballed chip is inspected for missing, bridged, or misshapen balls before it is placed.

When it is worth doing

Reballing is most common when genuine replacement ASICs are scarce and a working chip must be reclaimed from a scrap board, or when a chip was lifted for inspection and needs to be reseated. It demands the correct stencil for that exact chip package, good temperature control, and a steady hand, which is why it is firmly chip-level rework rather than a field repair.

Reballing sits between two related operations: see BGA (Ball Grid Array) for the package geometry it restores, and Reflow for the heating step that places the reballed chip back on the board.