odd-form
The form or
configuration of a
non-standard
component (such as
transformers, coils,
and large
connectors) that may
be difficult to
handle by automatic
placement equipment.
OEM =
Original Equipment
Manufacturer
Manufacturer of a
product that is
intended to perform
a function when
operated by an end
user, as opposed to
a manufacturer that
builds components
that go into such
equipment.
off-grid
Circuit board
features that are
not located on a
grid intersection.
Omegameter
An instrument that
measures ionic
residues on PCBs by
immersing an
assembly into a
water/alcohol
mixture having a
known high
resistivity, and
measuring and
recording, over a
specified period,
the drop in
resistivity
resulting from ionic
residues going into
solution.
OMPAC
Motorola
acronym for their
OverMolded Plastic
Array Carrier, a
specific type of
ball grid array
component.
opacity
The level of
transmissibility of
light through a
material. It refers
to the ability to
read markings
covered by conformal
coating or solder
mask material on a
PCA.
open
(open circuit)
An unwanted break in
the continuity of an
electrical circuit
which prevents
current from
flowing.
open
entry socket
One where the entry
for the mating plug
contact is open such
that the socket
contact is
vulnerable to damage
if not mated
correctly.
operating
voltage The
nominal voltage that
a circuit component
needs in order to
function properly.
operational
environment
See
environment.
optical
alignment mark
See
fiducial.
orientation marking
Information printed
on a circuit board
that provides
component location
information for the
assembly of
polarized or
multi-leaded parts.
outgassing
Refers to gaseous
emissions from
solids or liquids,
usually caused by
exposure to high
operating
temperatures and/or
altitude (low
external pressure).
Outgassing may come
from absorbed gas,
from the
vaporisation of
volatile
contaminants, or
from the breakdown
of constituent
materials. In a
printed circuit
board, outgassing
may result in
delamination; in a
solder joint,
outgassing during
reflow may create
voids.
overlay
See
inspection overlay.
overstressed
Material or
component exposed to
operating conditions
beyond specified
limits.
oxide
Materials formed by
the reaction of
elements with
oxygen. In the case
of soldering
materials, oxides
are formed by
reactions between
the surface metals
and oxygen in the
air. This process is
accelerated by high
temperature. Oxides
vary enormously in
physical properties:
some are flaky and
poorly adherent,
such as the oxides
and hydroxides found
in rust, and some
highly adherent,
such as the
aluminium oxide
layer created during
the ‘anodising’
process. For
soldering, the
oxides of tin, lead
and copper interfere
with the proper
wetting of solder
and need to be
removed or dispersed
before soldering, an
operation which is
usually carried out
by flux. See
oxidation.
oxidation
A chemical process
involving the
combination of a
material (usually a
metal) with oxygen
to produce a
substance with
substantially
different physical
and electrical
characteristics from
the base material.
