This paper reviews one of the single most important, but sometimes overlooked or taken for granted, aspects of the electronics industry – The PCB Design Grid System. Mixing PCB Design Layout units will compromise perfection every time. PCB Design perfection starts with building CAD library parts and quickly moves to part placement, via fanout and trace routing challenges. Outputting data for machine production can be extremely complex or very simple based on the PCB Design Layout units that were used throughout the PCB design process.