HDI :: High Density Interconnects

Like high density urban living, where people are stacked together in town houses and large apartment buildings, high density components require the high count input/output connections of HDI.

The HDI isn’t used just the connections between Printed Circuit Boards (PCBs), like the freeways connecting the cities; it’s in the fabrication of the PCB itself and the connections to the components, like the city streets and alleys between the dwellings and apartment buildings.

Fine Pitch

Surface Mount Technology (SMT) with its fine pitch components requires the printed circuit board miniaturization of HDI:

  • Tight tolerances
  • Densely spaced traces and pads
  • Multiple layers on a single PCB
  • Micro-vias to carry signals from one layer to another

This PCB miniaturization of HDI, or reduction in size and weight, goes hand in hand with this greater density of surface mount components. Of course, the high count connections for integrated circuits like BGAs and flip-chips, just adds to this need for the miniaturization of HDI.

HDI Design Advantages

The smaller size and weight of the HDI circuitry means the circuit boards fit into small spaces and have less mass than conventional printed circuit designs. The smaller size and weight also means there’s a lower chance of damage from mechanical shocks.

Considerations for HDI Assembly

The placement of the components on the printed circuit board requires more accuracy than conventional PCB design because of the small pads and fine pitch of the circuitry on the printed circuit board.

BGAs and Flip-Chips necessitate special soldering techniques and added steps in the assembly and rework (repair) process.


Let the engineers at RushPcb Inc work with you on the engineering and design of your HDI printed circuit boards.

For more information on Flex PCBs, contact us at sales@rushpcb.com, or call us at 408-496-6013.

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