Technical language barriers are quite commonplace today, and
most of us have been confronted with at least a few elements
of such a barrier from time to time. Advances in technology,
and the introduction of new or unfamiliar product areas, all
require an expansion of our technical vocabulary if we are
to communicate effectively. Hopefully, this edition of the
Glossary will serve as a valuable reference for improved
communications.
Acceptable Quality Level:
The maximum number of defects per every 100 units that are
considered to be satisfactory as a process average.
Acrylic:
A synthetic resin made from acrylic acid or a derivative
thereof. Acrylics possess the property of transparency, as
well as offer flame resistance.
Activated Rosin Flux:
A mixture of rosin and small amounts of organic-halide
activators or organic-acid activators.
Activators:
A substance that enhances the ability of a flux to remove
oxides and other contaminants from surfaces being joined.
Active Components:
Electronic components such as semiconductors, transistors,
diodes, etc., that can operate on an applied electrical
signal and change its basic characteristics (e.g.,
switching, amplification, rectification).
Active Hold-Down:
The process of pressing a component lead directly in contact
with a bonding pad during soldering to ensure intimate
contact between the lead and pad. Intimate contact is
important for proper heat transfer through the lead to
reflow the solder. This is a characteristic of hot bar
soldering, which utilizes a thermode to press the leads
against the bonding pads.
Additive Plating:
A process in which the conductive, resistive, and insulating
materials are successively plated to define traces, pads,
and elements.
Adhesion:
The state in which two surfaces are held together by means
of interfacial forces.
Adhesive:
A substance capable of holding materials together by surface
attachment.
Adsorption:
The adhesion of gases or liquid molecules to the surface of
solids or liquids with which they are in contact.
Aerosol:
Fluid or gas particles small enough to be airborne.
Aerosol:
Fluid or gas particles small enough to be sprayed.
Aging:
The change in the properties of a material over time and
under varying conditions of humidity, temperature, pressure,
etc.
Alignment Holes (or Tooling Holes):Holes
specifically designed in
TAB tape
for registration of a TAB frame. These holes can be located
virtually anywhere on the tape site, however, locations are
standardized in many cases.
Alloy:
A mixture of two or more metals combined to achieve
properties, such as a lower melting point or greater
strength, that the individual metals do not possess.
Analog Circuit:
An electrical circuit that provides a continuous
relationship between its input and output.
Angle of attack:
The angle between the squeegee face and the plane of the
stencil.
Anisotropic Conductive Adhesive:
Conductive adhesives that conduct electricity in one
direction only. Also referred to as "Z-axis conductive
adhesives." When using this type of adhesive, high Z-axis
forces are required during bonding. Components attached
using this material use the pick, place, and attach process.
Anisotropic:
A material that exhibits different properties when tested
along axes in different directions.
Annular Ring:
That portion of conductive material completely surrounding a
hole.
AOI:
(Automatic Optical Inspection) To inspect a pattern or
object using a camera in an automated system.
APQP:
Advanced Product Quality Planning is a structured method of
defining and establishing the steps necessary to assure that
a product satisfies the customer. The goal of a product
quality planning is to facilitate communication with
everyone involved to assure that all required steps are
completed on time.
AQL:
Abbreviation for "Acceptable Quality Level". A method of
random sampling rather than 100 percent inspection.
Aqueous Cleaning:
A cleaning technique that uses water as the primary cleaning
fluid.
Aqueous Flux:
An organic-chemical soldering flux that is soluble in water.
Area Array TAB:
A mounting configuration for a TAB frame to an IC where the
inner leads are connected to bumps in an array pattern on
the surface of the IC instead of on the perimeter, which is
the case for typical TAB components.
Array:
A group of elements, such as solder bumps, or circuits
arranged in rows and columns on a substrate.
ASIC:A
custom made circuit used for a specific application.
Assembly:
A group of components physically joined to a PCB or ceramic
board.
ATE:
Equipment that automatically analyzes functional or static
parameters to evaluate performance.
Automated Test Equipment:
Automatic optical inspection:
Azeotrope:
A blend of two or more polar and nonpolar solvents that act
as a single solvent and can be used to remove both polar and
nonpolar contaminants.
Azeotropic Mixture:
A liquid mixture of two or more substances that behaves as a
single substance.
- B -
B-Stage PCB:
Refer to "prepreg."
Bake Out:
Subjecting a laminate to an elevated temperature in order to
remove moisture and unwanted gases prior to final sealing.
Ball Grid Array:
Bare Board:
An unassembled (unpopulated) printed board.
Bed-of-Nails Fixture:
A test fixture consisting of a frame and holder containing a
field of spring-loaded pins that make electrical contact
with a planar test object.
Bend Radius:
The radius at the inside of the bends at both the lead
shoulder leading to the leg and the base of the leg leading
to the foot.
BGA:
A leadless surface-mountable package in which solder ball
interconnects cover the bottom surface of the package in a
check board fashion. BGAs are reflow soldered to PCBs using a
mass reflow process.
Bias Cut:
Material cut at 45 degrees from the normal weave pattern.
Binder:
the organic or inorganic material which encapsulates and
holds together the base in reinforced or otherwise
heterogeneous composites.
Blind Via:
A via hole extending only to one surface of a printed
circuit board.
Blister:
A localized swelling and separation between any of the
layers of a laminated base material, or between base
material and conductive foil. It is a form of delamination.
Blow Hole:
A void caused by outgassing. (Outgassing is a gaseous
emission from a printed circuit assembly when exposed to a
reduced pressure or heat or both.
Board:
An organic printed circuit card or board on which smaller
components, cards, or modules can be mounted.
Body:
The insulating part of an interconnect.
Bond lift-off:
A failure by separation of a bonded (or soldered) lead from
the pad surface (substrate).
Bond Strength:
The force per unit area required to separate two adjacent
layers of a package. The force is applied perpendicular to
the surface of the package.
Bonding Alloy:
A term sometimes substituted for solder. The "bonding alloy"
can be application specific; the most common to fine pitch
bonding is eutectic Sn/Pb solder.
Bonding Pads:
Copper traces, or pads, on a substrate to which leads are
bonded. Dimensions and thermal path from the bonding pads
must be properly designed to achieve uniform solder reflow.
Bonding:
The joining of two materials. For instance, the attachment
of a component to a substrate.
Boundary Scan:
An approach to the testing of printed circuit board
assemblies that can be used to diagnose individual circuit
failures by embedding the test circuits into the board and
in the most failure-prone integrated circuits.
Bow:
The deviation from flatness of a board characterized by a
roughly cylindrical or spherical curvature such that if the
board is rectangular, its four corners are in the same
plane.
Breakaway panels:
PCBs held together with breakaway tabs to make handling,
placement and soldering easier and more efficient. Boards
are snapped apart at the end of processing.
Bridge:
Solder that effectively joins two conductors that should not
be electrically connected, causing a short.
British Thermal Unit (B.T.U.):
the quantity of heat required to raise the temperature of
one pound of water 1°F from 58.5°F to 59.5°F (its point of
maximum density).
Built-in Lead Stress:
The force within leads of a molded carrier ring or TAB
component that result in lead skew or splay after the
excising process. Possible causes include the dam bar
removal process, the stamping process used to produce lead
frames, or stress induced during prior thermal or mechanical
processing of the components.
Built-In Self Test:
An electrical testing technique in which hardware is added
to the chip to allow the integrated circuit to test itself
with minimal use of test equipment.
Bump:
A small mound formed on the device or the substrate pads
that can be used as a contact for face-down bonding. This is
a method of providing connections to the terminal areas of a
device.
Burn-In:
The process in which a device is electrically stressed by
subjecting it to an elevated temperature and voltage for an
adequate period of time to cause the failure of a marginal
device.
Butt Joint:
A solder joint where the end of the lead sits on the solder
pad.
- C -
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 :
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:
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 density:
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-usually 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-usually metals-that easily conduct
heat. Examples include copper, aluminum, and beryllia.
Conformal Coating:
A thin non conducting 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.
Dam Bar:
A temporary part of the lead frame used to inhibit the flow
of plastic during the molding process for molded carrier
ring (MCR) and plastic quad flatpack (PQFP) components. The
dam bar is removed prior to testing or placing the component
because it is a part of the copper lead frame and thus
shorts all of the leads together.
DCA:
Direct Chip Attach. A chip-to-substrate connection intended
to reduce the first level of packaging. Here, the silicon
die is inverted and mounted directly to the PCB. Also
referred to as chip-on-board technology.
Defect:
Any nonconformance to specified requirements by a unit or
product.
Deionized Water:
Water that has been treated to remove ionized material.
Delamination:
A separation between plies within the base material, or
between the base material and the conductive foil, or both.
Dendritic Growth:
The metallic growth between pads in the presence of moisture
and an electrical bias.
Density:
The weight of a material in relationship to its volume.
Design of Experiment:
Device:
An individual electrical circuit element that can't be
further reduced without destroying its intended function.
Dewetting:
A situation where a lead or pad was at one point in the
soldering process wetted by the solder, but due to extended
time or temperature, the presence of intermetallics,
volatiles or other causes, has become withdrawn from the
wetted surface.
Die Bonder:
The placement machine for chips in a chip-on-board process
line.
Die Bonding:
The attachment of an integrated circuit chip to a substrate.
Die Sorter:
Equipment that picks die from a wafer and presents them for
their next process step. When used in reference to bare die
placement machines, the die are presented for pick by the
machine's placement nozzles.
Die:
Integrated circuit chip as diced or cut from the finished
wafer.
Dielectric:
Non conducting material used to encapsulate circuitry and in
the manufacture of capacitors and printed circuit boards.
Diffusion:
A material transport phenomena that occurs in solids, and is
caused by the continual physical motion of atoms from one
position to another. This results in the flow of material
from regions of high concentration to regions of low
concentration.
Diltant:
Fluid characterized by an increase in viscosity with an
increasing shear rate.
DIP Socket:
A connector for a Dual In-Line Package, or one that has its
leads in two parallel rows.
Direct Chip Attach :
Direct Chip Attach Module :
A component type developed by IBM® consisting of a small
substrate with flip chips attached using the
DCA
process. This small substrate, or module, is now a component
with solder pads on the bottom side that can be mounted to a
board using conventional surface mount processes.
Dispersants:
Organic and inorganic phosphates and polymers used in
aqueous cleaning to assist in the removal of insoluble
particles.
DOE:
(Design of Experiment) Procedure for establishing an
experiment in which the results (output variables) can be
related to a structured set of factors (input variables).
Double-Sided Assembly:
A fully assembled PCB with components on both sides of the
substrate.
Downtime:
The period in which equipment is not producing product owing
to maintenance or failure.
Dross Content:
A measure of the cleanliness of solder powder.
Dross:
Any oxide or other contamination formed on the surface of
molten solder.
Dry Film Photoresist:
Solid photoresist applied to a surface by lamination of
prefabricated film.
Dual In-Line Package (DIP):
A package with two rows of leads extending at right angles
from the base with standard spacing between the leads and
row. This package is intended for through hole mounting.
Durometer:
The measure of rubber or plastic hardness, as with the
squeegee blade.
Dynamic Flex:
A flex circuit in constant motion, for example, in a printer
head.
- E -
Elastomeric:
A material that at room temperature can be stretched
repeatedly to at least twice its original length, and upon
release of the stress, will return with force to its
approximate original length. A rubber band is an example.
Electro-Deposit Copper:
Copper used in manufacturing TAB tape. From a sputtered seed
layer of copper, the copper is electroplated (grown) to a
desired thickness, typically 1 ounce or 1.4 mils thick. The
copper is usually grown on a base material, and is separated
from this material upon completion of the deposition
process.
Electrode:
A conductor through which a current enters or leaves an
electrolytic cell, vacuum tube, or any nonmetallic
conductor.
Electroless Plating:
Deposition of metal (without any external electric current)
by an exchange reaction between metal complexes in the
solution and the metal being coated.
Electroplating:
A method of electrically depositing metals of very precise
compositions and thicknesses onto a base metal.
Electrolytic Corrosion:
Corrosion by means of electrochemical action.
Electromigration:
The electrolytic transfer of metal from one conductor to
another conductor separated from the first conductor by a
dielectric medium.
Electronic Packaging:
The technology of interconnecting semiconductor and other
electronic devices to provide an electronic function.
Electroplating:
Deposition of metal onto a cathodic surface by passing DC
current into an electrolytic solution.
Elongation:
the fractional increase in length of a material stressed in
tension.
Emissivity:
The ratio of the radiant energy emitted by a source to the
radiant energy of a perfect radiating surface (black box)
having an equivalent surface area with all other relevant
conditions being the same.
Emulsion:
A stable mixture of two or more immiscible liquids held in a
suspension by small percentages of emulsifiers.
Encapsulant:
The material used to cover
COB
devices to provide mechanical protection and to ensure
reliability, typically an epoxy.
Encapsulation:
The sealing or covering of an element or circuit for the
purpose of mechanical and environmental protection.
Epoxy Resin:
A material that forms straight chain thermoplastic and
thermosetting resins. Expoxy resins have excellent
mechanical properties and good dimensional stability.
Epoxy:
A thermosetting polymer containing the oxirane group.
Eutectic:
The minimum melting point of a combination of two or more
materials. The eutectic temperature of an alloy is always
lower than the melting point of any of its individual
constituents. The eutectic temperature is the particular
temperature at which the eutectic occurs. Eutectic alloys,
when heated, transform directly from a solid to a liquid and
do not show any pasty regions. For example, eutectic solder
paste has a composition of 63% tin (Sn) and 37% lead (Pb),
and has a eutectic temperature of 183ºC.
Excising:
Cutting component leads free from the remainder of the
package to prepare the component for forming or placement.
- F -
Failure:
The temporary or permanent functional impairment of a
component or device caused by physical, mechanical,
chemical, or electrical damage.
Fahrenheit:
equals 1.8 multiplied to the sum of the temperature in
Celsius and 32.
formula: - °F = 1.8 x (°C + 32)
Fiducial:
A specific mark incorporated in the circuit artwork and used
by machine vision to identify artwork orientation and
location.
Filler Materials:
Ceramic or metallic particles used to modify the properties
of polymers.
Fillet:
A smooth, concave junction where two surfaces meet. The
quality of a solder fillet determines the strength of the
joint.
Fine Pitch:
Surface mount components with a lead pitch of at least 50
mils. Fine pitch is more commonly used to refer to
components with a lead pitch of 25 mils or less. These
packages usually require vision assistance for accurate
placement.
Fixture:
A device that interfaces the PCB to the process machine
center(s).
Flat Pack:
An integrated circuit package with leads on two or four
sides. The leads on these packages are either gull wing or
flat, and have standard spacing. Packages with a lead pitch
below 50 mils are referred to as fine pitch packages.
Flex Circuits:
Flexible printed circuit boards made using thin polyimide or
polyester film with copper circuitry on one or both sides of
the flex. Flex circuits can be single or multilayer.
Flip Chip Attach (FCA):
Flip Chip:
Any packaging scheme in which the active circuitry of an IC
is placed facing the surface of the substrate. So A leadless
structure which is designed to electrically and mechanically
interconnect to the circuit by means of an appropriate
number of bumps located on its face which are covered with a
conductive bonding agent. Examples are flip TAB and C-4.
flip chip interconnection:
In this process, the bumped device is mounted to the
substrate active side down. The technique is called "flip
chip" because the active circuitry faces down instead of up,
as in the case of wire bonded devices.
Flip TAB:
A mounting configuration for a TAB component where the
active circuitry of the IC is placed facing the surface of
the substrate.
Flood bar:
A device on a stencil-printing system that drags solder
paste back to the starting point after the squeegee has made
a printing stroke.
Fluorocarbon:
The liquid vaporized in Vapor Phase reflow soldering.
Flux Activation Temperature:
The temperature at which flux is active enough to remove
oxides from the metals being joined.
Flux Activity:
The efficiency of a flux to promote the wetting of a surface
with molten solder.
Flux Characterization:
Tests performed to determine the properties of fluxes and
flux residues.
Flux Residue:
A flux-related contaminant present on or near the surface of
a solder connection.
Flux Solder Connection:
A solder joint with entrapped flux, causing high electrical
resistance.
Flux:
A chemically- or physically-active formulation capable of
cleaning oxides and enabling wetting of metals with solder.
FMEA:
Failure Mode and Effects Analysis. An FMEA can be described
as a systemized group of activities intended to: 1)
Recognize and evaluate the potential failure of a
product/process and its effects, 2) identify actions which
could eliminate or reduce the chance of the potential
failure occuring, and 3) document the process.
Foot Angle:
The angle of the lead foot after lead forming with respect
to the plane defined by the bottom of the component.
Foot Length:
The part of the component lead that comes in contact with
the bonding pad on the substrate.
Footprint:
The pattern on the printed circuit board to which the leads
on a surface mount component are mated. Also called a land
or a pad.
FR:
Fire Retardant
FR-1:
Is basically the same as FR2. FR1 has a higher TG of 130ºC
instead of 105ºC for FR2. Some laminate manufacturer which
produce FR1 will not produce FR2, since cost and usage are
similar and there is no advantage for having both.
FR-2:
FR2 is a Paper material with phenolic binder.
FR-3:
FR3 is mainly a european product. It is basically FR2 - but
instead of phenolic resin it uses a epoxy resin as binder.
The basic layer is paper.
FR-4:
FR4 is a glass fiber epoxy laminate. It is the most commonly
used PCB material. 1.60mm FR4 uses 8 layers of glass fiber
material. It is usually transparent. The green color comes
from the solder mask in the PCB finished product.
Functional Test:
The electrical testing of an entire assembly that simulates
the intended function of the product.
Gang Bonding:
A process in which multiple mechanical or electrical bonds
are made by means of a single stroke of a bonding tool.
GelPak:
A matrix tray style feeder without pockets, that consists of
a tacky gel over a mesh. The components are placed in a
regular array on the tray and are held in place by the tacky
gel. When picking components, vacuum is applied through the
bottom of the tray, pulling the gel through the mesh and
releasing the die.
Glass Fabric:
Glass yarns woven in a specific pattern.
Glass Transition Temperature:
The temperature above which a polymer loses its properties
of glass and behaves as an elastomer. Glass transition
temperature is characterized by a decrease in elastic
modulus and an increase in CTE.
Golden boy:
A component or assembly tested and known to function to
spec, then used to test other units via comparison.
Green Strength:
The strength of a substance, joint, or assembly before it
has been cured.
Ground Plane:
An electrically-conductive plane in a multilayer circuit
that connects a number of circuit elements to grounding
electrodes.
Gull Wing Lead:
A lead configuration, usually found on small outline
packages, where the leads are bent. The end view of these
packages resembles a gull in flight.
- H -
Halide:
Compounds containing fluorine, chlorine, bromine, iodine or
astatine. They may be part of a flux system (as activators)
and, as corrosives, must be removed.
Halide Content:
The ratio of the mass of free halides to the mass of solids
in a flux, expressed in mass percent of free chloride ions.
Halo:
A bright or dark ring around a drop of molten solder on a
flat surface.
Hard water:
Water containing calcium carbonate and other ions that may
collect on cleaning equipment interiors and cause clogging.
Hardener:
A chemical added to a resin to advance curing, i.e., a
curing agent.
Heat Treating:
A process that uses precise heating and cooling of metals
after stamping and forming in order to optimize internal
stresses and spring properties.
Hermetic:
The sealing of an object so it is airtight.
Hot Bar Soldering:
A process in which a heated bar simultaneously solders all
the leads of a device to the pads on a PCB.
Hot Gas Reflow:
A solder reflow process that uses a heated gas, including
air, as the mode of heat transfer.
Hydrophilic Solvent:
Refer to "polar solvent."
Hydrophobic Solvent:
Refer to "nonpolar solvent."
- I -
ICT:
An electrical test of a PCB assembly in which each component
is tested individually, even though many components are
soldered to the PCB.
ILB Window:
The opening in TAB tape where the innermost extremities of
the lead are bonded to the IC.
In-Circuit Test:
Inert Atmosphere:
A gaseous atmosphere that is not conducive to chemical
reactions, such as helium or nitrogen.
InfraRed (or IR) Reflow:
A technique in which long wavelength light serves as the
heat source to reflow solder and form solder joints.
Innovation:
Innovation is the whole process from: invention,
development, pilot production, marketing, production.
Invention is just invention (.Innovation = creative idea +
implementation.)
IR Shadowing:
When connector bodies or other components prevent the
infrared energy from directly striking some solder joints,
causing non-uniform heating.
Injection Molded Boards:
Printed circuit boards made by molding filler-reinforced
resins into a desired shape. Routing and through hole
metallizations are performed by seeding and plating, or by
printing. An alternative approach is to transfer mold the
interconnect directly onto the injection molded cards.
Inner Lead Bonding (ILB):
The process of attaching the IC to a TAB tape site.
Inner Lead:
The innermost portion of the lead on a TAB tape site that
extends into the ILB window.
Inner Ring:
A strip of polyimide between the inner and outer lead
bonding areas on a TAB tape site. This strip typically
encircles the entire IC. It is a common feature in many
TAB tape
designs, but is not found in all cases.
Inorganic Flux:
An aqueous flux solution of inorganic acids and halides.
Insulators:
A class of materials that do not conduct electricity and are
characterized by high resistivity.
Integrated Circuit:
A microcircuit that consists of interconnected elements
inseparably associated and formed in-situ on or within a
single substrate, usually silicon, to perform an electronic
circuit function.
Interconnect:
The conductive path required to achieve connection from one
circuit element to another.
Interconnection:
The conductive path required to achieve a connection from a
circuit element to the remainder of the circuit.
Interleaver:
A polyester film used to protect and separate TAB tape
layers. It is used whenever
TAB tape
or TAB components are handled in a continuous tape format.
Intermetallic:
Chemical compounds formed between the metals present in the
solder, base metal and protective platings. Intermetallic
formation is necessary for good solder joints, but excessive
intermetallics can cause brittleness.
Isotropic Conductive Adhesive:
Isotropic adhesives conduct electricity in all directions.
This means the adhesive can be dispensed only on those areas
(pads) where a circuit path is required (i.e., where bumps
