PCB Terminology (Part 1)
It is always good to know a bit of PCB terminology. Here is a reference table with the most common words.
Thou: A “thou” is a thousandth of an inch and equivalent to a “mil”.
Mil: A “mil” is a thousandth of an inch and equivalent to a “thou”.
mm: “mm” is short for millimeter, a thousandth of a meter.
ESD: Electrostatic discharge caused by static electricity.
Trace: A path made of copper on a PCB. It is used in the same manner as electrical wires, to connect the components of a board.
Via: A hole with copper inside to provide electrical connection between a trace on one layer to a trace on a different layer of the PCB.
Pad: Pads are used to solder surface mount devices to the board.
Annular Ring: The annular ring is the area that is left of a pad after a hole has been drilled in it.
Silkscreen: Markings of component names, values and outlines on a PCB for simpler assembly and debugging. Usually white.
Solder Mask or Solder Resist: A substance that solder won’t stick to. Used to make sure traces are insulated electrically and physically. This is usually applied to the whole board except from where there are pads to be soldered.