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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.
Celsius: also referred
to as Centigrade, is equal to the difference between the temperature
in Fahrenheit less 32 and the quantity divisible by 1.8.
formula: °C = (°F-32) ÷ 1.8
CEM: Composite Epoxy
Material
CEM-1: CEM-1 is a paper
based laminate with one layer of woven glass fabric. It is
not suitable for PTH.
CEM-3: CEM-3 is a laminate
very similar to FR4. Instead of woven glass fabric a 'flies'
type is used. CEM-3 has a milky white color and is very smooth.
It is a complete replacement for FR4 and has a very large
market share in Japan.
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.
Control Limit: Lines
drawn on a control chart that illustrate the boundaries of
variation from sample to sample, or roll-to-roll. It is calculated
from process data. It is not an arbitrary boundary.
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 Clad Laminate:
laminates (i.e. FR4) having copper foil bonded to one or both
surfaces and intended primarily for use in printed circuits.
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.
Cp Index: (Capability
Performance) A measure of the relationship between the allowable
process spread (part tolerance) and the actual process spread
(natural tolerance). (A Cp value greater than 1.0 indicates
that the process is capable of achieving its desired results.)
Cpk Index: (Process
Capability Index) Ability to meet a customer's specification.
A measure of the relationship between the scaled distance
between the process mean value and the closest specification
limit.
Crazing: Minute lines
appearing in or near the surface of materials such as plastics,
usually resulting as a response to environment. Crazing cannot
be felt by running a fingernail across it (if the fingernail
catches , it is a crack).
CTE: (Coefficient of
Thermal Expansion) A characteristic thermomechanical property
of a material or a composite. It is the tendency of a material
to expand as it is heated. In laminate, in-plane (x and y
direction) and out-of-plane (z-direction).
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.
CTI: Comparative Tracking
Index. Indicates the highest usable voltage for alaminate.
It becomes important in application with high humidity, such
as washing machines or cars. A higher index means a better
protection. Similar is 'PTI' and 'KC'.
Cure: to change the
physical, chemical, or electrical properties of a material
by chemical reaction, by the action of heat and catalysts
alone or in combination, with or without pressure. Specifically
to convert a low molecular weight polymer or resin to and
insoluble, infusible state.
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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