Manage Multiple Signals with HDI

摘要

New circuit board designs require signal paths that can handle multi-GHz signals and dense wiring due to high I/O count, as well as wide lines for RF or high-speed digital signals and narrower lines for digital signals With standard circuit board stack-ups, it is difficult to satisfy all those constraints at once. HDI technologies address these challenges. Most existing organic circuit board technologies create via stubs that can only be avoided with restrictive design rules, and they do not have the flexibility to build arbitrary transmission-line structures. The challenges for constructing organic circuit boards that meet these electrical requirements include using highspeed, low-loss materials; manufacturing precise structures; and making a reliable finished product. A high-density interconnect (HDI) circuit board technology* involves building mini circuit boards of three or four layers each, then assembling several of these thin boards together to make the finished product. Designing and manufacturing the thin circuit boards separately, then assembling them together, makes it possible to reliably manufacture circuit boards with no via stubs, using low-loss materials and nearly arbitrary transmission line structures, with flexibility in fine-tuning features to reduce signal loss.