ZT The effects of vias on PCB ...

The effects of vias on PCB tracesUltraCAD Design, Inc.

DESIGN NOTE

THE EFFECTS OF VIAS ON PCB TRACES
Background: Through the years we have worked with many engineers who have had strong feelings about the presence of vias on critical traces (such as fast rise time clock lines). These feelings have ranged from (a) the effects of vias are so negligible that they may be used freely, to (b) their effects are so significant that vias may not be used at all. Depending on your view, these two extremes place quite different constraints on PCB designs! It is clear from the history of all the boards that have ever been designed in the past that vias have little impact at lower frequencies and rise times. It is only recently, as device rise times and timing issues caused by faster clock speeds have become critical PCB design issue