HDI board (High Density Interconnector), that is, high-density interconnection board, is a circuit board with a relatively high line distribution density using micro-blind and buried via technology. The HDI board has an inner layer circuit and an outer layer circuit, and then uses processes such as drilling and metalization in the hole to realize the internal connection of each layer of the circuit.

HDI boards are generally manufactured by layer-by-layer method, the more the number of layers, the higher the technical grade of the plate. Ordinary HDI boards are basically one-time build-up. High-end HDI uses two-time or more build-up technology. At the same time, advanced PCB technologies such as stacking holes, electroplating and filling holes, and laser direct drilling are used. When the density of the PCB increases beyond the eight-layer board, it is manufactured with HDI, and its cost will be lower than that of the traditional and complex pressing process.

HDI board has higher electrical performance and signal accuracy than traditional PCB. In addition, HDI boards have better improvements in radio frequency interference, electromagnetic wave interference, electrostatic discharge, and heat conduction. High-density integration (HDI) technology can make terminal product designs more compact, while meeting higher standards of electronic performance and efficiency.