0.8-mm Pin Pitch BGAs, Part 3

摘要

This article focuses on the use of any-layer-vias in which the micro-vias traverse only two layers individually; however, they can be stacked to span any set of layers including starting on therntop and ending on the bottom of the board. It is my belief that this general methodology will increase in popularity quickly and will eventually become the predominant via model for all PCBs.rnA footprint for a Virtex-5 with 1760 pins (1227 I/Os) at 1-mm pitch was converted to 0.8-mm pitch as the basis for the tests.rnThis test uses an any-layer-via stackup in which every layer is buildup and has a via-hole in it.