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Symbology
AC Alternating Current
CMOS Complimentary Metal Oxide Semiconductor
COB Chip-on-Board
CTE Coefficient of Thermal Expansion
CTExy X and Y-Axis Coeff of Thermal Expansion
CTEz Z-Axis Coeff of thermal expansion
DC Direct Current
DIP Dual In-line Package
DWB Discrete Wiring Board
ECL Emitter Coupled Logic
EMI Electromagnetic Interference
FR-4 Epoxy Glass Dielectric Material
HL High-to-Low signal Edge Transition
IC Integrated Circuit
KB Backward Crosstalk
KF Forward Crosstalk
LG Ground Plane Inductance
LH Low-High Signal Edge Transition
LP Power Plane Inductance
PWB Printed Wiring Board
RC Series Lead Resistance
RG Ground Plane Resistance
RP Power Plane Resistance
RT Sheet Resistance
SM Surface Mount
TAB Tape Automated Bonding
Tan (δ) Dissipation Factor (Loss Tangent)
TDR Time Domain Reflectometer
TP Total Signal Line Propagation Delay Time
TPD Propagation Delay Per Unit Length
TR 10%-90% Edge Transition Time (Rise or Fall)
TTL Transistor Transistor Logic
Zo Characteristic Line Impedance (Unloaded)
Zo' Characteristic Line Impedance (Loaded)
εr Relative Permittivity
εr' Effective Relative Permittivity
δ Skin Depth
Terms and Definitions
AC Impedance – the combination of resistance, capacitive, reactance, and inductive reactance seen by AC and/or time-varying voltage.
Alternating Current - a current that varies with time. This label is commonly applied to a power source that switches polarity many times per second, such as the power supplied by utilities. May take a sinusoidal shape, but could be a square or triangular wave shape.
Amplitude – the height or magnitude of a voltage signal as measured with respect to a reference plane, such as signal ground.
Annular Ring – copper pad surrounding a plated through hole.
Aspect Ratio – relationship between hole size and board thickness.
B-Stage (Pre-Preg) – semi cured resin system used to bond cores together.
Blind Via – vias that originate at either the top or bottom layer of the board and terminate at an inner layer.
Buried Vias – vias that both originate and terminate on inner layers.
Dual-Strip Line – a stripline signal conductor that is embedded between two ground planes, and is not centered between them.
Attenuation – Reduction in the amplitude of a signal due to losses in the media through which it is transmitted.
Backporching – a term used to describe the reflections which follow a fast rise or fall time signal traveling down a long transmission line that has not been properly terminated. Look like a stair step.
Backward Crosstalk – Noise induced into a quiet line placed next to an active line as seen at the end of the quiet line close to the signal source.
Busbar – a large copper or brass bar used to carry high power supply currents onto a printed board or backplane
Capacitance – a measure of the ability of two adjacent conductors separated by an insulator to hold a charge when a voltage is impressed between them. (F)
Class I Materials, Supplies, and Services – materials used as direct materials in deliverable product and supplies and/or services that have a direct effect on the quality of the product, such as chemistries, drill bits, outside processing, and calibration.
Coaxial – a term used to describe conductors that are concentric about a central axis. Take the form of a central wire surrounded by a conductor tube that serves as a shield and ground. May have a dielectric other than air between the conductors.
Continuity Verification – defined as checking the quality of an electrical connection between two or more points. The quality of a connection is determined by evaluating the maximum continuity resistance of the connection.
Core – sheet of resin coated with copper foil on both sides.
Crossover – intersection of two conductors separated by insulation
Crosstalk (coupling) – the transfer of energy between to adjacent circuits via capacitive or inductive coupling.
Customer Procurement Documents – all information that defines the customer’s end product requirements. This information includes data, specs, drawings, statements of work, ECNs, waivers, Pos, customer files, etc.
Decoupling – absorbing noise pulses generated in the power supply lines by switching logic so as to prevent them from disturbing other logic on the same power supply circuit. Usually done with capacitors.
DFM – Design for manufacturability.
Differential Pair – Parallel routed signals exhibiting mutual impedance between both lines, typically 50 to 120 ohms.
Dimensional Stability – dimensional changes in the material impact layer-to-layer registration. Advanced techniques or controls may be required to utilize less stable materials.
Direct Current – a current produced by a voltage source that does not vary with time. Normally provided by power supplies to power electronic circuits
Discrete Wiring Board – circuit board using round insulated wire to form signal paths, terminated by a plated through hole.
Dissipation Factor – a factor used to express the tendency of insulators or dielectrics to absorb some of the energy in an AC signal.
Edge Rate – the rate of change in voltage with time of a logic signal transition. Usually expressed in volts per nanosecond.
Edge Transition Attenuation – the loss in sharpness of a switching edge caused by absorption of the highest frequency components by the transmission line.
Effective Relative Permittivity – the ratio of the permittivity of the material to that of free space (dielectric constant) experienced by an electrical signal transmitted along a conductive path.
Electromagnetic Interference (EMI) – radiated electromagnetic energy that couples into conductors where it is not wanted.
Features – all copper areas in a PWB design.
Flat Conductor – a rectangular conductor that is wider than it is high. Usually refers to signal conductors in a printed wiring board.
Forward Crosstalk – Noise induced into a quiet line placed next to an active line as seen at the end of the quiet line farthest from the signal source.
Ground – a term used to describe the terminal of a voltage source that serves as a measurement reference for all voltages in the system; often the negative terminal of the power source, but sometimes the positive terminal.
Impedance – the resistance to the flow of current represented by an electrical network. May be resistive or reactive, or both.
Inductance – the property of a conductor that allows it to store energy in a magnetic field induced by a current flowing through it. (H)
Isolation Testing – defined as checking for minimum isolation resistance values between nodes (or nets) not included for connection.
Line Coupling – coupling between two transmission lines cause by their mutual inductance and the capacitance between them.
Load Capacitance – the capacitance seen by the output of a logic circuit or other signal source. Usually the sum of distributed line capacitance and input capacitances of the load circuits.
Logic – a general term used to describe the functional circuits used in computers and other digital electronics to perform computational functions. Logic family – a collection of logic functions or ICs using the same form of electronic circuit to perform computation.
Machinabiliity – the relative ease with which a material can be drilled, punched, and routed; will impact the cost of fabrication.
Microstrip - transmission line that consists of a narrow conductor separated from an infinite ground place by a layer of dielectric material.
Net – point to point on a board.
Panelization – process of super imposing several circuits onto a Unicircuit manufacturing panel.
Parallel Pair – two conductors that travel side by side at a controlled spacing over a long distance.
Percent Defective Allowable (PDA) Limits – max number of rejects allowable (as a percentage of the inspection lot size) before the lot must be rejected. PDA limits apply to electrical test, microsection, analysis, and innerlayer, sub assembly, and final inspection, as defined by associated spec sheets of MIL – PRF – 31032.
Permeability – a general term used to express various relationships between magnetic induction and magnetizing force.
Permittivity (dielectric constant) – the ratio of the permittivity of the material to that of free space.
Poisons Ratio – ratio of lateral strain to longitudinal strain.
Power Dissipation – energy used by an electronic device in the performance of its function.
Printed Wiring Board – a circuit board utilizing etched copper traces for signal interconnections.
Propagation Delay – the time required for a signal to travel along a transmission line, or the time required for a logic device to perform its function and present a signal at its output.
Pulse – A logic signal that switches from one state to the other and back in a short period of time, and remains in the original state most of the time. Usually used as clocks fro logic devices.
Purchase Order – an order form, which authorizes supplier(s) to ship material or perform a service. All Pos must have approved purchase requisition prior to formal or informal transmittal to supplier(s).
Purchase Requisition – a form, which describes the material and/or services to be procured. Designate individuals only, who have authority to commit company funds, approve this form.
Reflection – Energy from a high-speed signal edge that is sent back toward the source as a result of encountering a change in impedance in the transmission line on which it is traveling,
Repair – act of restoring the functional capability of a defective article in a manner that prevents the articles from being in full compliance with applicable drawings/specs.
Rework – the act of reprocessing non-compliant materials, through the use of original or alternative equivalent processing, in a manner that assures compliance of the article with applicable drawing/specs.
Rise Time – Time required for a logic signal to switch from its low state to its high state. Commonly measured between the 10% and 90% voltage levels.
Signal Line – Any conductor used to transmit a logic signal from one circuit to another.
Skin Effect – An increase in the inductive lines of flux that will cause the density of the current to concentrate on the surface of the trace instead of through the entire trace caused by a decrease in operating frequency and the inductive element dominating the resistive element.
Stripline – a narrow conductor embedded between two AC ground places.
Stub – a branch of the main line of a signal net usually used to reach a load that is not on the direct signal path.
Supplier Profile – an attachment to PO that defines standard quality clauses, supplier responsibilities, and deliverables. This profile is intended to be retained by class I suppliers and is automatically invoked with each order, unless otherwise specified.
Tg – glass transition temperature.
Transmission Line – any form of conductor used to carry a signal from a source to a load. The transmission time is usually long compared to the speed or rise time of the signals, so the coupling, impedance, and terminators are important to preserving signal integrity.
Waveguide – a rectangular or round tube used to transmit microwave energy in the form of an electromagnetic wave rather than a current in a wire.
Young’s Modulus – the ratio of unit stress to unit strain.