High Density Interconnect (HDI)
High Density Interconnect (HDI) is defined as a printed circuit board with a higher wiring density per unit area than a conventional PCB. They have much finer lines and spaces, smaller vias and capture pads, and higher connection pad density than employed in conventional PCB technology. HDI PCB is made through Microvia and buried vias and sequential lamination with insulation materials and conductor wiring for higher density of routing.
HDI PCB is used to reduce size and weight, as well as to enhance electrical performance of the device. HDI PCB is the best alternative to high layer-count and expensive standard laminate or sequentially laminated boards. HDI incorporate blind and buried vias that help to save PCB real estate by allowing features and lines to be designed above or below them without making a connection. Many of today's fine pitch BGA and flip-chip component footprints do not allow for running traces between the BGA pads. Blind and buried vias will only connect layers requiring connections in that area.
Laser drill, voids-desmear / deash, inter-layer registration through sequential lamination.
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