User:MichaelFrey/non functional pad

A non functional pad is a pad in a printed circuit board, that is not connected to a track on the layer is on.

Non functional pads removal
Non functional pads can be removed at any phase of the design process. Some software allows precise control during the design process. Some software removes the non functional pads during output file creation. Some board manufactures remove non functional pads during data preparations.

Sometimes, Non functional pads removal is also called Unused Pad Supression.

Benefits and drawbacks
The benefits are:
 * electrically
 * less parasitic capacity
 * improved drill process
 * drills last longer
 * drills do not break as often
 * the drilled holes are smoother
 * less wandering of the drill

Non functional pads removal can influence the reliability. (e.g. barrel cracking failure mode) In some cases, removing the non functional pads increases the reliability, but in some cases, it decreases reliability.

Depending in design parameters, removing the non functional pads can free up routing space.

Non functional pads off-course also effect thermal characteristic.

Some times, non functional pads or the removal of non functional pads is used for chopper balancing, which affects etching, bow and twist and other effects.

Weblinks

 * https://www.dfrsolutions.com/hubfs/DfR_Solutions_Website/Resources-Archived/White-Papers/Reliability/Non-Functional-Pads-Should-they-Stay-or-Should-they-Go.pdf
 * https://www.polarinstruments.com/support/reliability/pads-nopads.pdf
 * http://ecss.nl/glossary/non-functional-pad/