Importance of Proper Return Paths for the HDI Boards

As the electronic industry continues to push the envelope of extreme miniaturization, product development teams are being forced further into the realm of high density interconnect and micro via technology. Design techniques labeled exotic only a few years ago are now considered mainstream. In particular, build-up substrates usage has grown dramatically, and is now found in a large percentage of high end production electronic products. With this transition from the LDI to the HDI boards, there is a threat posed to the continuity of the return paths for the densely routed signals on the PCB which are routed by changing the different layers. This paper is a caveat to one such observation with simulated data to backup the experiment.