Herein disclosed are an apparatus, a system and a method, selectively linking signals between or among slots on a backplane. A backplane printed circuit board has defined slots, each of which receives a card or module. One or more arrays of solder ball mounting pads correspond to signal lines of the slots. Each of one or more signal mapping overlay printed circuit boards has at least one signal trace connected to solder ball landing pads. Selected solder ball mounting pads of the backplane printed circuit board are connected to selected solder ball landing pads of the signal mapping overlay printed circuit board by solder balls. The signal trace or traces of the signal mapping overlay printed circuit board or boards connect the corresponding selected signal lines between or among the slots of the backplane. The backplane and signal mapping overlay printed circuit boards may have mirrored connection arrays.