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

HDI circuit boards are generally manufactured by layer-by-layer method, the more the number of layers, the higher the technical level of the board. Ordinary HDI circuit boards are basically one-time build-up, high-end HDI uses two or more build-up techniques, while using advanced PCB technologies such as stacked holes, electroplating and filling, and laser direct drilling.

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 Multi-layer PCB is conducive to the use of advanced packaging technology, and its electrical performance and signal accuracy are higher than traditional PCBs. In addition, HDI circuit boards have better improvements in radio frequency interference, electromagnetic wave interference, electrostatic discharge, and heat conduction.

Electronic products continue to develop toward high density and high precision. The so-called "high", in addition to improving machine performance, also reduces the size of the machine. High-density integration (HDI) technology can make terminal product designs more compact, while meeting higher standards of electronic performance and efficiency. At present, most popular electronic products, such as mobile phones, digital (camcorder) cameras, notebook computers, automotive electronics, etc., use HDI circuit boards. With the upgrading of electronic products and market demand, the development of HDI circuit boards will be very rapid.