fan-out wafer level package (FO-WLP)

Fan-outwafer level packaging( FO-WLP) is an interconnect technology in which the fan-outs are connected together as a chip-to-chip connection. This is the case, for example, with 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 far as fan-outs are concerned, there are usually more of them than fan-ins. FO-WLPs can also be used in memory chips designed as package-on-package( PoP), thereby increasing the compactness of the packages and reducing the overall height. Corresponding chips are used in mobile devices.