April 1, 2008 -- A major requirement in improving board fabrication yields is doing it right the first time, because once the PCB fabrication process is complete there is really no way to go back to fix major mistakes. In some cases you can mitigate design issues during the PCB assembly process, but during PCB fabrication, once layers are laminated and the holes are drilled, you cannot easily undo the process to make corrections.

Therefore, to improve fabrication yields during and after design layout, it’s critical to follow the detailed fabrication notes and drawings, specifically calling out every item that requires any kind of explanation. This includes stack up data, layer construction information, material call outs, as well as drill charts specifying hole counts and symbols, whether drill holes are plated, and any similar information.

By Zulki Khan. (Khan is president and founder, Nexlogic Technologies.)