By Eric Bogatin, originally published in Circuitree Magazine, June 1999
HDI technology, also known as micro via or buildup circuit boards, uses fine lines, thin dielectric layers and vias typically 5 mils in diameter that connect adjacent layers. Boards using this technology have a few performance advantages because of the small vias and short interconnects. In this feature article, we review the physical features of HDI substrates and the electrical performance that is possible.