Once a wafer is completed, it is normally probed to determine which die on it pass and which die fail. This information, along with some reference die is output as a wafer map.

An optical inspection test (AOI) may also be made on each die in the wafer. The AOI machine may read in a map file in order to know which die to inspect and it can write out a map file to report on the inspection results.

After the wafer is tested, it is sliced up and the individual (singulated) die are arrayed on a sticky plastic membrane. A pick and place machine or a die attach machine then uses the map file from the prober (or the AOI) to select good die and place them in "bins" or perhaps the good die are directly attached to an package.

In any event, for this process to work, the map file produced by the probing machine must be read by the die pick-and-place equipment or die attach equipment.