Fan Out Chip Last Package (FOCLP) is a FOWLP technology developed by ASE. Copper pillar bumped die are mass reflowed onto a low cost coreless substrate, followed by overmolding, which also serves to underfill the die. The Cu pillars allow die connection at 50um or below, negating requirement for RDL on the die. The Cu pillars are bonded to one side of the copper trace (down to 15um L/S) and solder balls are directly bonded to the other side. This makes the “substrate” be effectively as thick as the copper in the traces and allows the final package to be as thin as 400um. Implementation with multiple die, inclusion of passives and 3D structures can all be implemented.