Overhang

Increase in printed circuit conductor width caused by plating build-up or by undercutting during etching.

Outgrowth

The increase in conductor width at one side of a conductor, caused by plating build-up, over that delineated on the production master.

Outgassing

The gaseous emission from a laminate printed board or component when the board or the printed board assembly is exposed to heat or reduced air pressure or both.

OSP

Organic Solderable Preservative.

Organic Activated (OA)

A water-soluble flux using organic acids as activators.

Open

An area of a bare PCB which, due to over-etching or fabrication problems, separates two electrically connected points.

One-sided Board

See Single-sided Board.

Omegameter

A test instrument measuring ionic residues on PCBs via the drop of resistivity over a specific time.