Advanced RDL Packaging
FOPoP
ASE's Fan-Out Package on Package is a thin RDL-based vertical integration platform that improves electrical and thermal performance for mobile processors, optical networking, and other products where bandwidth and form factor are critical.
What is Fan-Out Package on Package?
FOPoP combines a fan-out bottom package with a standard package mounted above it. Fine-pitch copper posts connect top and bottom RDL routing planes through the mold, replacing the interposer used by a conventional PoP.
The RDL-first wafer-level process enables thinner, finer traces while keeping the top and bottom packages separable for qualification, sourcing, yield, and logistics.
Dense vertical integration
A substrate-less bottom package lowers parasitic inductance and shortens the electrical path. Double-sided RDL, landside capacitors, and near-die deep-trench capacitors can add routing and power-integrity capability for advanced silicon nodes.
- Nearly 40% lower profile than substrate-based package-on-package structures
- Higher interconnect density through finer RDL line and space
- Shorter electrical paths and improved thermal performance
- Known-good top packages can be tested before final assembly
Mobile and networking applications
For networking and co-packaged optics, 3D stacking shortens the path between photonic and controller ICs. ASE reports electrical-path reduction of up to 3× and bandwidth-density gains of up to 8× for optical-engine integration.
FOPoP also supports application processors with memory, ASICs with antenna-in-package modules, automotive electronics, and compact AR, VR, and MR devices where package height and battery space are at a premium.
