In electronics, you can assemble components (resistors, capacitors, logic elements) simulated: you can for example build a new micro-processor multi-million transistors (3.1 to pentium).
The establishment was a little painful at first because of necessity to take existing plans. It was realized at that time that statistically almost 10% of trading on existing plans were inaccurate, as references plans were duplicated, a single reference could correspond to several slightly different planes, etc.. Ultimately, the greater reliability of the information proved to be an important additional argument deciding to generalize CAD, which forms PCB Footprint.
The computer-aided design is at the intersection of several fields: computer drawing, scientific computing, constraint programming. CAD systems add peripheral features, such as CFD which allows you to take into account the equations of thermodynamics to study the behavior of the modeled system with the PCB systems.
