HDI is the English abbreviation for High Density Interconnector. High-density interconnect (HDI) manufacturing is one of the fastest growing areas in the printed circuit board industry. From the first 32-bit computer from HP in 1985 to the large client server with 36 sequential multi-layer printed boards and stacked micro-vias, HDI/mini via technology is undoubtedly the future PCB architecture. Smaller ASICs and FPGAs with smaller device spacing, I/O pins, and embedded passives have shorter rise times and higher frequencies, all of which require smaller PCB feature sizes, which drives Strong demand for HDI/mini vias. HDI process First-order process: 1+N+1 Second-order process: 2+N+2 Third-order process: 3+N+3 Fourth-order process: 4+N+4