activator One or more ingredients in a flux
that create a wettable surface for solder, by removing oxides and
possibly other contaminants when coming into contact with the metal
on the parts to be soldered. These ingredients may or may not be
corrosive at room temperature, but certainly must be active at
elevated temperatures in order to perform their job properly.
active component An electronic component whose
parametric characteristics change while operating on an applied
signal.
annular ring The portion of PWB conductor
material (with through-hole designs, usually a pad) that completely
surrounds a hole.
ANSI = American National Standards Institute An
organization that establishes US and international standards. ANSI
publications that are most applicable to printed circuits are those
that define drafting procedures and documentation formats.
antioxidant As used when referring to fluxes,
an antioxidant is a material that prevents re-oxidation of the
metal surfaces after the activator has prepared them for
soldering.
aperture A predetermined shape (round, square,
oblong, etc.), size (width, diameter), and type (draw or flash)
that is exposed on artwork film by a photoplotter.
aperture library A collection of standard
aperture descriptions.
aspect ratio The ratio of the length or depth
of a hole to its pre-plated diameter. Often used for the ratio of
the thickness of the board to the diameter of its smallest via
hole. Holes with high aspect ratios are difficult both to drill and
plate and may be susceptible to cracking.
assembly A number of parts or subassemblies or
any combination thereof that are joined together.
assembly drawing A document that shows the
physical relation of a combination of parts and subassemblies that
form a higher order assembly, giving both the locations of
components and their reference designators. See Bill of
Materials.
ATE = Automatic Test Equipment Programmable
equipment used for various testing operations. In bare PCB
manufacturing this would check for continuity, i.e. look for any
open or short circuits.
automated assembly Automatic component
placement and attachment to a printed circuit board.
automated optical inspection (AOI) A vision
system that captures and stores an image and compares it to an
expected image and/or expected data, in order to detect errors on
printed circuit boards, or assemblies.
autoplacement The activity by CAD software that
automatically places components on a circuit board layout based on
preset rules.
autorouter CAD layout software that
automatically determines the placement of interconnections on a
circuit board based upon predetermined design rules.
axial lead A lead wire extending from a
component body along its longitudinal axis.
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