Free PCB Design. CAD Programms/Software to realize Printed Circuit Boards

"A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, or traces, etched from copper sheets laminated onto a non-conductive substrate. from Wikipedia Printed Circuit Board

Given the complexity of electronic design, caused by the very fine features used and the need to very precisely align those features during manufacture and assemble, the need for computer aided design (CAD) software is imperative.

PCB (printed circuit board) layout optimization to avoid EMI (electromagnetic interference). A PCB layout should not only strive to prevent the emission of noise but also have good noise immunity from outside sources. One should have an understanding of potential sources of noise and have a strategy for dealing with these problems.