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C-4
(Controlled Collapse Chip Connection):
A solder joint connecting a substrate directly to an IC in
a flip chip configuration. In this packaging scheme, a solder
ball is formed on the IC, the IC is placed active circuitry
down onto a substrate, and the solder is reflowed. As the
solder melts, the solder balls collapse into a shape controlled
by the surface tension of the liquid solder while supporting
the weight of the IC.
C-5 (Controlled Collapse Chip Carrier Connection):
The same technology as C-4 except the IC is mounted in an
intermediate carrier (ceramic or FR-4) using conventional
technology, and the chip carrier, having the solder balls,
is mounted directly to the substrate and reflowed.
C-Stage:
Refer to "laminate."
CAD/CAM:
Computer-aided design is the use of special software tools
to formulate printed circuit patterns. Computer-aided manufacturing
translates such designs into actual products. These systems
include mass memory for data processing and storage, inputs
for design creation and output devices for converting stored
information into drawings and reports.
Capillary Action:
The effect of surface tension that draws a liquid into a small
opening. So a combination of natural causes that forces molten
solder to flow against gravity between closely spaced solid
surfaces.
Card:
A printed circuit board of smaller dimensions is commonly
referred to as a card. A card is generally one level lower
than the printed circuit board in the hierarchy of packaging.
A card is also referred to as a daughter board.
Ceramic Ball Grid Array (CBGA):
A ball grid array package with a ceramic substrate.
Ceramic Column Grid Array (CCGA):
The same as CBGA except the solder balls are replaced by solder
columns. The advantage of columns is that the inherent flexibility
of the columns help compensate for CTE mismatch between the
ceramic component and the FR-4 board. Columns are required
rather than solder balls for components greater than 25mm
square.
Ceramic:
An inorganic, nonmetallic material. Examples include alumina
or glass-ceramic. Ceramics are often used in forming ceramic
substrates for the packaging of semiconductor chips.
CFC:
A chlorinated fluorocarbon that can cause ozone layer depletion.
The use of CFCs is restricted by the Environmental Protection
Agency. CFCs are primarily used in air conditioning and refrigeration,
foam insulators, and cleaning solvents.
Chip Carrier:
An integrated circuit package that is usually square and may
possess a cavity for a chip in the center and whose connections
are typically on all four sides.
Chip-on-Board : (see
COB)
Chip:
The individual circuit or component of a silicon wafer. The
leadless form of an electronic component part, either passive
or active, discrete or integrated.
Circuit:
The interconnections of electrical elements and devices that
perform a desired electrical function.
Circuit
tester:
(see
ICT)
Clamshell Fixture:
An in-circuit test fixture designed to probe both sides of
a PCB.
Cleaning:
An operation involving the removal of flux residues and other
contaminants from the surface of a PCB assembly.
Cluster Testing:
A variation of the in-circuit testing procedure in
which a cluster of components are tested as a functional unit.
Coating:
A thin layer of material, conductive or dielectric, applied
over components or a base material.
COB:
A configuration in which a face-up bonded chip is directly
attached to a printed circuit board or substrate and exclusively
interconnected to the substrate conventionally, i.e., by flying
wires.
Coefficient of Thermal Expansion (CTE):
The ratio of change in dimensions to original dimensions per
degree rise in temperature, expressed in ppm/ºC.
Cofiring:
A process for forming multilayer ceramic substrates in which
thick- film conductors and dielectrics are simultaneously
processed by a firing cycle.
Cold
solder joint:
A connection reflecting poor wetting action and characterized
by a gray, porous appearance owing to insufficient heat or
inadequate cleaning.
Comb Pattern:
A set of comb-like arrays of uniformly spaced conductors.
Component:
An individual functional element in a physically independent
body (e.g., resistor, capacitor, or transistor).
Component
densityt:
The number of parts on a PCB divided by board area.
Component
Lead:
A wire or formed conductor that extends from a component and
serves as a mechanical and/or electrical connection. Leads
can readily be formed to a desired configuration.
Conduction:
The thermal transmission of heat energy from a hotter region
to a cooler region in the presence of a conducting medium.
Conductive Adhesive:
Refer to "isotropic/anisotropic conductive adhesives."
Conductor, Electrical:
A class of materials-ususally metals-that easily conducts
electricity. Examples include silver, copper, gold, and super-conducting
ceramics.
Conductive
Epoxy:
A polymer material made to pass electrical current by the
addition of metal particles, usually silver.
Conductor, Thermal
: A class of materials-ususally metals-that easily
conduct heat. Examples include copper, aluminum, and beryllia.
Conformal Coating:
A thin nonconducting coating that is either plastic or inorganic
and is applied to a circuit for environmental and mechanical
protection.
Contact Angle:
The angle between bonding material and a bonding pad. Also
called the wetting angle.
Contact Printing:
A type of printing where there is no gap between the stencil
and the substrate.
Contact Resistance:
The maximum resistance allowed between a pin and the socket
contacts of a connector when assembled and in use.
Contact Time:
Refer to "Dwell time."
Contaminant:
An undesirable material that can adversely influence the properties
of a material or the quality of a product. A contaminant can
be liquid or solid.
Continuous Tape:
A TAB tape handling scheme that uses a continuous reel of
polyimide tape to mount and carry TAB components through the
assembly process. Typically, the tape width conforms to industry
standards, with 35mm, 48mm, and 70mm widths being the most
common.
Convection:
The transfer of heat by movement of hot air. (Often used in
conjunction with infrared radiation to reduce the effect of
IR shadowing. )
Coplanarity:
The maximum distance between the lowest pin and the highest
pin when a package rests on a perfectly flat surface.
Copper
foil:
A cathode-quality electrolytic material deposited as a thin,
continuous sheet on substrates as a conductor for PCBs. It
readily bonds to insulators, accepts the printed resists and
etches out to form the circuit pattern.
Copper
mirror test:
A flux corrosivity test using a vacuum-deposited film on a
glass plate.
Corrosion:
A chemical action that causes the gradual deterioration of
the surface of a metal by oxidation or chemical reaction.
Corrosive Flux:
A flux that contain levels of activators like halides, amines,
or organic acids that can cause the corrosion of copper.
CTE Mismatch:
The difference in the coefficients of thermal expansions of
two materials or components joined together, which produces
strains and stresses at joining interfaces or in attachment
surfaces.
Curing Cycle:
The time-temperature profile needed to cure a thermosetting
material like a bonding adhesive.
Curing Time:
The time needed to properly cure a thermosetting plastic material.
Curing:
A change in the physical properties of a material via chemical
reaction or by reaction to temperature-time profile.
Cycle
rate:
A component placement term measuring machine speed from pickup
to board location and return. Also called the test rate.
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