fan-in wafer level package (FI-WLP)

Fan-InWafer Level Packaging (FI-WLP) is an interconnect technology in which the fan-ins of the chips are connected directly at chip level. A typical example is the superimposed dice of 3D chips.

When assigning the I/Os from the dice to the bumps, the aim is to define the position of the connections in such a way that the connections are as short as possible and thus the package can be constructed in the most space-saving way possible.

As for the fan-ins, they usually have fewer connections than fan-outs.