Evolution of flexible PCBs in particle detection: From ALICE ITS1 to future frontiers in microfabrication for ALPIDE chip integration

The use of ultra-lightweight flexible micro-cables in silicon-based particle detectors was pioneered for the first ALICE Inner Tracking System (ITS1) and the STAR tracker in the early 2000s. In this context, thin and flexible interconnections made of m-scale metal traces on dielectric substrates were specifically designed, offering a low material budget while exhibiting optimal mechanical stability and electrical properties. Over more than two decades of continuous progress in the field of PCB manufacturing have brought forth contemporary machinery that provides numerous advantages and possibilities for further integrating this technology into upcoming experiments. This study marks the initial phase of an R&D started from the concepts developed for the ALICE ITS1 experiment. It introduces innovative microfabrication techniques aimed at minimizing the material budget of PCBs. The preliminary results of integrating this technology with ALPIDE chips are presented.