Introduction: High-density HDI PCBs for optical communication call for specific three mil/3 mil trace/Place, Rogers or Panasonic M6 substrates, and electrolytic challenging gold finish for dependable 8-layer, 3–5 cm² https://bookmarkcork.com/story22471811/assortment-criteria-for-high-density-hdi-pcb-boards-in-optical-communication