A B C
D E F G
H I J K
L M N O
U V W X Y Z
Acceptance Inspection (Criteria)
An inspection that determines conformance of a product to design specifications
as the basis for acceptance.
A series of holes in successive layers of a multilayer board, each set having
their centers on the same axis. These holes provide access to the surface of the
land on one of the layers of the board.
An electronic component that can change a signal or respond to the signal in a way
that is dependent upon the nature of the signal and/or other controlling factors.
(This includes diodes, transistors, amplifiers, thyristors, gates, ASIC’s and other
integrated circuits that are used for the rectification, amplification, switching,
etc., of analog or digital circuits in either monolithic or hybrid form).
A process for obtaining conductive patterns by the selective deposition of conductive
material on clad or unclad base material.
A substance such as glue or cement used to fasten objects together. In surface mounting,
an epoxy adhesive is used to adhere SMDs to the substrate.
The metal layer that adheres a barrier metal to a metal land on the surface of an
The chemical process of preparing a surface to enhance its ability to be bonded
to another surface or to accept an over-plate.
Adhesive Coated Substrate
A base material upon which an adhesive coating is applied, for the purpose of retaining
the conductive material (either additively applied or attached as foil for subtractive
processing), that becomes part of a metal-clad dielectric.
A stylized pattern that is selectively positioned on a substrate material to assist
(See Figure A-2).
Anisotropic Conductive Contact
An electrical connection using an anisotropic conductive film or paste wherein conductive
particles of gold, silver, nickel, solder, etc. are dispersed. When it is compressed,
an electrical connection is attained only in the direction of compression.
Annular Ring (Annular Width)
That portion of conductive material completely surrounding a hole. (See Figure A-4).
Figure A-4 Annular Ring (Annular Width)
The electrode from which the forward current flows within the device.
An accurately-scaled configuration that is used to produce the "Artwork Master"
or "Production Master." (See Figure A-6.)
Aspect Ratio (Hole)
The ratio of the length or depth of a hole to its preplated diameter. (See Figure
Figure A-7 Aspect Ratio (Hole)
An intermediate stage in the reaction of a thermosetting resin in which the material
softens when heated and swells, but does not entirely fuse or dissolve when it is
in contact with certain liquids. (See also “C-Staged Resin.”)
A land in flexible printed wiring that has a portion of the side normally bonded
to the base dielectric material exposed by a clearance hole. (See Figure B-2).
Ball Grid Array (BGA)
A surface mount package wherein the bumps for terminations are formed in a grid
on the bottom of a package.
(See Figure B-3).
Figure B-3 Ball Grid Array (BGA
An unassembled (unpopulated) printed board.
The film that is the base material for the flexible printed board and on the surface
of which the conductive pattern can be formed. .
A test fixture consisting of a frame and a holder containing a field of spring-loaded
pins that make electrical contact with a planar test object.
Cutting a sheet of material into pieces to the specified outline.
A via extending only to one surface of a printed board. (See Figure B-9.)
Figure B-9 Blind and Buried Vias
Delamination in the form of a localized swelling and separation between any of the
layers of a laminated base material, or between base material and conductive foil
or protective coating, or solder mask.
The force perpendicular to a board&39;s surface required to separate two adjacent layers
of the board, expressed as force per unit area.
Fine gold or aluminum wire used for making electrical connections between lands,
lead frames, and terminals.
A via that does not extend to the surface of a printed board. (See Figure B-9.)
A problem solving tool that uses a graphic description of various process elements
in order to analyze potential sources of process variation.
The resistance of a parallel conductor structure to the flow of alternating current
(AC), usually applied to high speed circuits, and normally consisting of a constant
value over a wide range of frequencies.
The resistance of an insulating material to the degradation of surface characteristics,
such as surface roughness, swelling, tackiness, blistering or color change, beyond
the specified allowance by exposure to chemicals such as acids, alkalis, salts,
A low-profile, usually square, surface-mount component semiconductor package whose
die cavity or die mounting area is a large fraction of the package size and whose
external connections are usually on all four sides of the package. (It may be leaded
Semiconductor chip mounted directly onto flexible printed board.
Chip Scale Package (CSP)
The direct attachment of a chip to a substrate without an interposer.
A number of electrical elements and devices that have been interconnected to perform
a desired electrical function.
A layer of a printed board containing conductors, including ground and voltage planes.
A hole in a conductive pattern that is larger than, and coaxial with a hole in the
base material of a printed board.
(See Figure C-6.)
Figure C-6 Clearance Hole
Coefficient of Thermal Expansion (CTE)
The linear dimensional change of a material per unit change in temperature. (See
also “Thermal Expansion Mismatch.”)
Production master or artwork data that has been enlarged or reduced in order to
meet the needs of subsequent processing requirements.
Computer-Aided Design (CAD)
The interactive use of computer systems,
programs, and procedures in the design process wherein the decision-making activity
rests with the human operator and a computer provides the data manipulation function.
A sheet of metal that is used to form a conductive pattern on a base material.
A low viscosity liquid medium with a suspended powder of an electrically conductive
The ability of a substance or material to conduct heat.
A single conductive path in a conductive pattern that includes traces, conductive
holes, lands, and planes.
A reduction in a conductor trace cross-sectional area (internal or external) which
may or may not expose the base material.
The observable distance between adjacent edges (not center-to-center spacing) of
isolated conductive patterns in a conductor layer. (See Figure C-10.) (See also
Figure C-10 Conductor Spacing
The observable width of a conductor trace at any point chosen at random on a printed
board as viewed from directly above .
An insulating protective covering that conforms to the configuration of the objects
coated (e.g. Printed Boards, Printed Board Assembly) providing a protective barrier
against deleterious effects from environmental conditions.
A device used to provide mechanical connect/disconnect service for electrical terminations.
A plastic shell that holds electrical contacts in a specific field pattern that
may also have polarization/keying bosses or slots.
The electrical resistance of metallic surfaces, under specified conditions, at their
interface in the contact area.
The mass of copper per unit area for a foil, typically expressed in ounces per square
foot or grams per square centimeters (these units are not equivalent).
Material deposited as a liquid onto the circuitry that subsequently becomes a permanent
dielectric coating (See “Cover Material”).
Film made from i) a homogeneous, single component; ii) separate layersof
generically similar chemistries; or iii) as a composite blend (See “Cover
Film and adhesive made from separate layers of generically different chemistries.
(See “Cover Material”).
Cpk Index (Cpk)
A measure of the relationship between the scaled distance between the process mean
value and the closest specification limit.
The breaking up of large conductive areas by the use of a pattern of voids in the
conductive material. (See Figure C-13).
Figure C-13 Crosshatching
Marking of products to indicate their date of manufacture.
A separation between plies within a base material, between a base material and a
conductive foil, or any other planar separation within a printed board. (See also
The process of exposing a photoresist to a chemical solution which dissolves unwanted
material and without affecting wanted material. The standard method of distinguishing
between wanted and unwanted material is by polymerizing the resist so as to make
it less soluble in the development solvent.
The uncased and normally leadless form of an electronic component that is either
active or passive, discrete or integrated.
A material with a high resistance to the flow of direct current, and which is capable
of being polarized by an electrical field.
The complete failure of a dielectric material that is characterized by a disruptive
electrical discharge through the material that is due to deterioration of material
or due to an excessive sudden increase in applied voltage.
The ratio of the capacitance of a configuration of electrodes with a specific material
as the dielectric between them to the capacitance of the same electrode configuration
with a vacuum or air as the dielectric. See “Permittivity.”
The process of removing copper from a conductive pattern that has been plated on
a starting thin copper foil such that the portions of the thin starting foil are
completely removed and the thicker plated portions are slightly reduced by the etchant.
A measure of the dimensional change of material that is caused by factors such as
temperature changes, humidity changes, chemical treatment (aging), and stress exposure.
Double-Sided Printed Board
A printed board with a conductive pattern on both of its sides.
Dry Film Resist
A composite material where a photosensitive emulsion that is sensitive to portions
of the light spectrum and is either carried by or sandwiched between polymer release
films and is used to expose imagery on printed boards.
The distance of a pattern or component body from the edges of a printed board. (See
A metal foil that is produced by electrodeposition of the metal onto a material
acting as a cathode.
The ratio of the depth of etch to the amount of lateral etch, i.e., the ratio of
conductor thickness to the amount of undercut. (See Figure E-3).
Figure E-3 Etch Factor
The controlled removal of non-metallic materialsfrom the sidewalls of holes in order
to remove resin smear and to expose additional internal conductor surfaces.(See
Figure E-4 Etchback
The chemical, or chemical and electrolytic, removal of unwanted portions of conductive
or resistive material. (See Figure E-5.)
Figure E-5 Etching Indicator
The process of generating a pattern within a photosensitive material through a chemical
reaction using either laser direct imaging or conventional imaging with a working
A printed board feature (or features) that is (are) created in the same process
as the conductive pattern and that provides a common measurable point for component
mounting with respect to a land pattern or land patterns.
A part or assembly that has been manufactured prior to the start of a production
run for the purpose of ascertaining whether or not the manufacturing processes used
to fabricate it are capable of making items that will meet all applicable end-product
Flexible Multilayer Printed Board
Multilayer printed board, either printed circuit or printed wiring, using flexible
base materials only. Different areas of the flexible multilayer printed board may
have different number of layers and thicknesses.
Flexible Printed Circuit
A patterned arrangement of printed circuitry and components that utilizes flexible
base material with or without flexible coverlay.
A type of data that consists of aperture selection and operation commands and dimensions
in X- and Y-coordinates. (The data is generally used to direct a photoplotter in
generating photoplotted artwork.)
Hot Air (Solder) Leveling (HASL)
A physical deposition process using a solder bath into which the printed board is
immersed into a molten solder bath and withdrawn across a set of hot air knives
(forced hot air flow) used to remove excess solder.
The chemical deposition of a thin metallic coating over certain basis metals that
is achieved by a partial displacement of the basis metal.
The resistance to the flow of current, represented by an electrical network of combined
resistance, capacitance and inductance, in a conductor as seen by an AC source of
varying time voltage. The unit of measure is ohms.
Foreign particles, metallic or nonmetallic, that may be entrapped in an insulating
material, conductive layer, plating, base material, or solder connection.
A product made by bonding together two or more layers of material.
The process of bonding one or more innerlayers together with an adhesive layer or
layers (such as pre-preg) utilizing a combination of heat and pressure.
A portion of a conductive pattern usually used for the connection and/or attachment
Laser Direct Imaging (LDI)
The selective exposure of patterns onto a photosensitive material (such as dry film
or liquid) without using a working phototool (artwork master).
The process of aligning circuit features (lands) on individual layers of a printed
board through the use of tooling image location features (fiducials) or tooling
Lead Free Solder
An alloy that does not contain more than 0.1% lead (Pb) by weight as its constituent
and is used for joining components to substrates or for coating surfaces.
A fiducial mark (or marks) used to locate the position of a land pattern for an
individual component on a printed board.
A hole or notch in the panel or printed board to enable either to be positioned
A collection of units produced in one continuous, uninterrupted fabrication run.
A linear dimension equal to 1 x 10-6 meters or 39.4 x 10-6
A transmission line (See “Transmission Line”) structure that consists of a signal
conductor that runs parallel to and is separated from a much wider reference plane.
(See Figure M-3).
Figure M-3 Microstrip
Microvia (Build-Up Via)
A blind or subsequently buried hole that is < 0.15 mm [< 0.006 in] in diameter and formed
either through laser or mechanical drilling, wet/dry etching, photo imaging, or
conductive ink-formation followed by a plating operation.
Minimum Annular Ring
The minimum ring of metal(s) at the narrowest point between the edge of a hole and
the outer edge of a circumscribing land. (This determination is made to the drilled
hole on internal layers of multilayer printed boards and to the edge of the plating
on external layers of multilayer and double-sided printed board.)
The flared condition of copper on an inner conductive layer of a multilayer printed
board that is caused by hole-drilling.
(See Figure N-1.)
Figure N-1 Nail Heading
An artwork, artwork master, or production master in which the pattern being fabricated
is transparent to light and the other areas are opaque.
An entire string of electrical connections from the first source point to the last
target point, including lands and vias.
The plating of an entire surface of a panel including holes.
The passing of an electrical current through a high-resistance space between two
parallel electrodes in order to provide the energy required to make a welded termination.
A problem-solving technique whereby all potential problem areas or sources of variation
are ranked according to their contribution to the end result.
The selective plating of a conductive pattern and associated holes.
The force per unit width that is required to peel a conductor foil from a laminate
perpendicular to the surface of the substrate.
A photographic process whereby an image is generated by a controlled-light beam
that directly exposes a light-sensitive material.
A photo-chemically reactive material, which polymerizes upon exposure to ultraviolet
energy at a given wavelength customarily used to define an etching, plating, or
selective stripping pattern on a substrate.
A phototool is a physical film, Mylar (or similar), which contains the pattern
that is used to produce a circuitry image on a photo-sensitive material by way of
exposure to light-energy such as UV light. (see also "Artwork," "Artwork Master,"
"Production Master," "Working Master.")
A chemical solution containing metal ions used in plating a metal-film on a substrate.
Also may be referred to as an electrolyte.
An isolated location where the plating is absent or the plating thickness is less
than the minimum specified copper thickness.
The synthetic polymer that has more than two ester radicals in the main chain.
The synthetic polymer that has more than two imide radicals in the main chain.
A sheet of material that has been impregnated with a resin cured to an intermediate
stage, i.e., B-staged resin.
The degree of conformity of the position of a pattern (or portion thereof), a hole,
or other feature to its intended position on a product.
Rigid-Flex Printed Board
A printed board with both rigid and flexible base materials.
A drawing that shows, by means of graphic symbols, the electrical connections, components
and functions of a specific circuit arrangement.
The transferring of an image to a surface by forcing a suitable media with a squeegee
through an imaged-screen mesh.
The process of manufacturing multilayer printed boards in which multiple double-sided
printed boards with interconnecting holes between conductive patterns on both sides
are laminated or combined, after which additional layers (usually single-sided)
are attached to the partially completed board stackup.
A physical barrier, usually electrically conductive, that reduces the interaction
of electric or magnetic fields upon devices, circuits, or portions of circuits.
A slender portion of plating overhang that is partially or completely separated
from a conductor edge.
A metal alloy with a melting temperature that is below 427 °C [800 °F].
A small sphere of solder adhering to a laminate, resist, or conductor surface. (This
generally occurs after wave solder or reflow soldering.)
Solder, with a normally concave surface, that is at the intersection of the metal
surfaces of the solder connection.
Solder Mask .
A heat-resisting coating material applied to selected areas to prevent the deposition
of solder upon those areas during subsequent soldering.
A metal or rubber blade used to wipe a material (ink or solder paste) across a stencil
or silk screen to force the material through the openings in the screen or stencil,
onto the surface of a printed board or mounting structure.
A via/microvia structure formed by stacking one or more build-up vias/microvias
in a build-up multilayer providing an interlayer connection between three or more
The attaching of metallic devices, such as solder terminals and eyelets, by the
upsetting of the portion of the device that protrudes through a hole in a base material.
Stencil (Solder Paste/Adhesive)
A thin sheet of material containing openings to reflect a specific pattern, designed
to transfer a paste-like material to a substrate for the purpose of component attachment.
A method of dimensionally positioning multiples of the same or intermixed functional
patterns accurately within a given area on the phototool or by repetitious contact,
projection printing or photoplotting.
A material fastened to the surface of a flexible circuit to increase its mechanical
Strip (Resist Stripping)
The process of removing unneeded masking material, such as a photoresist or metallic
etch resist, after a processing step is completed.
A transmission line structure that consists of a signal line that runs parallel
to and is sandwiched between and separated by a dielectric from two reference planes.
A plastic that undergoes a chemical reaction when exposed to elevated temperatures
that leads to it having a relatively infusible or crosslinked stated that cannot
be softened or reshaped by subsequent heating.
The application of molten solder to a basis metal in order to increase its solderability.
A bond formed when a wire is pressed against the bonding pad and the pressing mechanism
is ultrasonically vibrated at high frequency (above 10kHz).
A plated-through hole that is used as an interlayer connection, but in which there
is no intention to insert a component lead or other reinforcing material. (See also
"Blind Via" and "Buried Via.")
The spreading of molten solder or glass on a metallic or nonmetallic surface, with
proper application of heat and in some cases flux.
A slender, acicular metallic growth filament that is between a conductor and a land.
The capillary absorption of a liquid along the fibers of a base material. (See also