advanced

**Advanced Fan-Out RDL** is **fine-pitch redistribution layers on substrate enabling dense signal routing from chiplets to package pads** — substrate-level wiring at ~10-15 μm pitch. **RDL Purpose** redistribute signals from micro-bumps to larger package pads. **Trace Width** 5-10 μm width; advanced lithography. **Via Density** micro-vias ~5-10 μm diameter at similar pitch. **Dielectric** low-k polymers (polyimide) or SiO₂. **Copper Traces** low resistivity routing; oxidation/passivation protected. **Pattern Transfer** lithography + etching or laser patterning. **Multiple Layers** stacking 2-4 RDL layers increases density. **Via-to-Via** spacing 20-50 μm between layers. **Signal Integrity** impedance control; crosstalk mitigation. **Power Distribution** large-area traces carry power; low resistance. **Solder Mask** protective coating; openings for bumps. **Fan-Out** signals spread from compact chip to larger substrate pads. Density advantage. **Test Points** integrated test access; online testing. **Cost** processes mature; volume reduces cost. **Panel-Level** large substrate processing increases throughput. **Advanced RDL enables routing density matching logic** for high-density packaging.