Multi-Side Photolithography with Paste-Like Materials for Advanced PCB and Substrate Fabrication

The continuous demand for finer interconnects in advancedpackaging and high-density PCB substrates has pushed currentsemi-additive processes (SAP/mSAP) close to their physical andeconomic limits. This proposal introduces a novel concept thatcombines paste-like, light-sensitive materials with multi-sidephotolithography to enable three-dimensional structuring ofconductive and dielectric features. By leveraging controlledexposure from multiple angles, this approach has the potential tocreate sub-5 μm line/space interconnects and complex 3Dgeometries beyond the capabilities of conventional planarphotolithography. Such a method could provide a cost-effectiveand scalable path for next-generation CoWoS/CoWoP substrates,high-bandwidth memory (HBM) integration, and heterogeneoussystem-in-package (SiP) architectures.