Application and Processing Technology of HDI PCB

blind holes pcb

HDI PCB (High Density Interconnector PCB), is a circuit board having a relatively high line distribution density using the micro-blind and buried hole technology.

It is a process that includes an inner layer line and an outer layer line, then uses a hole and a metallization in the hole to realize a joint function between the inner layers of each layer.

With the development of high-density, high-precision electronic products, the same requirements are imposed on circuit boards. The most effective way to increase the density of pcb is to reduce the number of through holes, and to accurately set the blind holes and buried holes to achieve this requirement, thereby generating an HDI board.


  1. The Concept

HDI: High Density Interconnection Technology. It is a multilayer board made by a build-up method and a micro-blind buried hole.

Micro-hole: In a PCB, a hole less than 6 mil (150 um) in diameter is called a micro-hole.

Buried Via: buried in the inner layer of the hole, not visible in the finished product, mainly used for the conduction of the inner layer line, can reduce the probability of signal interference, and keep the continuity of the characteristic impedance of the transmission line. Since the buried via does not occupy the surface area of the PCB, more components can be placed on the surface of the PCB.

Blind Via: connecting the surface layer and the inner layer without passing through the full-board via holes.


  1. The Process


High-density interconnect technology can be divided into

  • The first-order process: 1+N+1;
  • The second-order process: 2+N+2;
  • The third-order process: 3+N+3.

Blind hole produce process

HDI PCB board