Reballing involves dismantling, heating the chip until it can be removed from the board, typically with a hot-air gun and vacuum pickup tool, removing the device, removing solder remaining on the device and board, putting new solder balls in place, replacing the original device if there was a poor connection, or using a new one, and heating the device or board to solder it in place. The new balls can be placed via several methods, including:
Using a stencil for both the balls and the solder paste or flux,
Using a BGA “preform” with embedded balls corresponding to the device pattern, or
Using semiautomated or fully automated machinery.