|
PCB
Glossary Active
Components:
Semiconductor devices, such as transistors and diodes, that can change its basic
characteristics in an powered electrical circuit, such as amplifiers and
rectifiers. Analog
Circuit:
An electrical circuit that provides a continuous quantitative output as a
response from its input. Annular
Ring:
The width of the conductor pad surrounding a drilled hole. Artwork:
Printed circuit design. Aspect
Ratio:
The ratio of the board thickness to the smallest-hole diameter of the printed
circuit board. Assembly
File: A
drawing describing the locations of components on a PCB. Automated
Test Equipment (ATE):
Equipment that automatically tests and analyzes functional parameters to
evaluate performance of the tested electronic devices. Ball
Grid Array (BGA):
A SMD package in which solder ball interconnects cover the bottom surface of the
package. Bare
Board:
An unpopulated PCB. Base Copper Weight: see Copper Foil BBT:
Bare
Board Test. Built-In
Self Test: An
electrical testing method that allows the tested devices to test itself with
specific added-on hardware. CAD:
Computer
Aided Design. CAM:
Computer
Aided Manufacturing. CAM
Files: The
files used for manufacturing PCB including Gerber file, NC Drill file and
Assembly Drawings. Ceramic
Ball Grid Array (CBGA):
A ball grid array package with a ceramic substrate. Chip-on-Board
(COB):
A configuration in which a chip is directly attached to a printed circuit
board or substrate by solder or conductive adhesives. Chip:
The individual circuit or component of a silicon wafer, the leadless form
of an electronic component. Component
Side: The
Side of a PCB on which most of components are mounted. Coating:
A thin layer of material, conductive, magnetic or dielectric, deposited on a
substance surface. Coefficient
of Thermal Expansion (CTE):
The ratio of dimensional change of an object to the original dimension
when temperature changes, expressed in %/ºC or ppm/ºC. Contact
Angle (Wetting Angle):
The angle between the contact surfaces of two objects when bonding. The contact
angle is determined by the physical and chemical properties of these two
materials. Copper
Foil (Base Copper Weight):
Coated copper layer on the board. It can be either characterized by
weight or thickness of the coated copper layer.
For instance, 0.5, 1 and 2 ounces per square foot are equivalent to 18,
35 and 70 um thick copper layers. Corrosive
Flux:
A flux that contains corrosive chemicals such as halides, amines,
inorganic or organic acids that can cause oxidation of copper or tin conductors. Curing:
The irreversible process of polymerizing a thermosetting epoxy in a
temperature-time profile. Curing
Time:
The time needed to complete curing of an epoxy at a certain temperature. DFSM:
Dry
Film Solder Mask. Die:
Integrated circuit chip as diced or cut from a finished wafer. Die
Bonder:
The placement machine bonding IC chips onto a chip-on-board substrate. Die
Bonding:
The attachment of an IC chip to a substrate. Dielectric:
An
insulating medium between conductors. DIP:
Dual
in-line package with two rows of leads from the base in standard spacing between
the leads and row. DIP is a through-hole mounting package. Double-Sided
Assembly: PCB
assembly with components on both sides of the substrate. DRC:
Design rule check. Dry
- Film Resists:
Coated photosensitive film on the copper foil of PCB using photographic
methods. They
are resistant to electroplating and etching processes in the manufacturing
process of PCB. Edge
Connector:
A connector on the circuit-board edge in the form of gold plated pads or
lines of coated holes used to connect other circuit board or electronic device. Edge
Clearance:
The smallest distance from any conductors or components to the edge of the PCB. Electroless
Deposition: The
chemical coating of a conductive material onto a base material surface by
reduction of metal ions in a chemical solution without using electrodes compared
to electroplating. Electroplating:
The
electrochemical deposition of reduced metal ions from an electrolytic solution
onto the cathode by applying a DC current through the electrolytic solution
between two electrodes, cathode and anode, respectively. ESR:
Electro-statically applied Solder Resist. Fine
Pitch:
Fine pitch is more commonly referred to surface-mount components with a
lead pitch of 25 mils or less. Finger
—A
gold-plated terminal of a card-edge connector. Also see Gold Finger. Flux:
The
material used to remove oxides from metal surfaces and enable wetting of the
metal with solder. FR4:
Flame Retardent laminate made from woven glass fiber material impregnated
with epoxy resin. Functional
Test:
The electrical testing of an assembled electronic device with simulated
function generated by the test hardware and software. Gerber
File:
Data file used to control a photoplotter. Ground
Plane: A
conductive plane as a common ground reference in a multilayer PCB for current
returns of the circuit elements and shielding. GI:
The woven glass fiber laminate impregnated with polyimide resin. Gold
Finger —The
gold-plated terminal of a card-edge connector. Also see Finger. HDI:
High Density Interconnect. Hermetic:
Airtight sealing of an object. In-Circuit
Test:
Electrical test of individual component or part of the circuit in a PCB
assembly instead of testing the whole circuit. Hole
Density: The
number of holes per unit area on a PCB. Interstitial
Via Hole: An
embedded through-hole with connection of two or more conductor layers in a
multilayer PCB. Laminate:
A
composite material made by bonding together several layers of same or different
materials. Lamination:
The process manufacturing a laminate using pressure and heat. Leakage Current: A small amount of current that flows across a dielectric area between two adjacent conductors. Legend:
A
format of printed letters or symbols on the PCB, such as part numbers and
product number or logos. LPI:
Liquid
Photo-Imageable solder mask that uses photographic imaging to control a thinner
mask deposition than the dry film solder mask. Minimum
Conductor Width:
The smallest width of any conductors, such as traces, on a PCB. Minimum
Conductor Space:
The smallest distance between any two adjacent conductors, such as
traces,
in a PCB. Multilayer
PCB: Circuit
boards consisting three or more layers of printed circuits separated by laminate
layers and bonded together with internal and external interconnections. NC Drill: Numeric Control drill machine used to drill holes at exact locations of a PCB specified in NC Drill File. Netlist: List of parts and their connection points which are connected in each net of a circuit. Node:
A
pin or lead to which at least two components are connected through condcutors. NPTH:
Non-plated
trough-hole. Pad:
The
portion of a conductive pattern for connection and attachment of electronic
components on the PCB.
Also called Land. PCB:
Printed Circuit Board. Also called Printed Wiring Board (PWB). PCMCIA:
Personal Computer Memory Card International Association. PEC:
Printed Electronic Component. Pick-and-Place:
A manufacturing operation of assembly process in which components are
selected and placed onto specific locations according to the assembly file of
the circuit. Pitch:
The center-to-center spacing between conductors, such as pads and pins,
on a PCB. Plastic
Leaded Chip Carrier (PLCC):
A component package with J-leads. PTH
(plated-through Hole):
A
plated hole used as a conducting interconnection between different layers or
sides of a PCB either used as connection for through-hole component or as a via. Plating
Resist: Material
deposited as a covering film on an area to prevent plating on this area. Reflow
Soldering: Melting,
joining and solidification of two coated metal layers by application of heat to
the surface and predeposited solder paste. Resist:
Coating
material used to mask or to protect selected areas of a pattern from the action
of an etchant, solder, or plating. Route
(or Track): A
layout or wiring of an electrical connection. Screen
Printing:
A process for transferring an image from a patterned screen to a
substrate through a paste forced by a squeegee of a screen printer. Silk Screen (Silk Legend): Epoxy-ink Legend printed on PCB. The most common colors used are white and yellow. Small
Outline Integrated Circuit (SOIC):
An integrated circuit with two parallel rows of pins in surface mount
package. SMOBC:
Solder
mask over bare copper. SMD:
Surface Mount Device. SMT:
Surface
Mount Technology. Solder
Bridging:
Solder connecting, in most cases, misconnecting, two or more adjacent
pads that come into contact to form a conductive path. Solder
Bumps:
Round solder balls bonded to the pads of components used in face-down
bonding techniques. Solder
Mask or Solder resist:
Coating
to prevent solder to deposit on. Solder
Wick:
A band of wire removes molten solder away from a solder joining or a
solder bridge or just for desoldering. Temperature
Coefficient (TC):
The ratio of a quantity change of an electrical parameter, such as resistance or
capacitance, of an electronic component to the original value when temperature
changes, expressed in %/ºC or ppm/ºC. Test Point: A specific point in a circuit board used for specific testing for functional adjustment or quality test in the circuit-based device. UL:
Underwriter’s
Laboratories. A popular safety standard for electrical devices supported by many
underwriters. Via:
A
plated-through hole used for interconnection of conductors on different sides or
layers of a PCB. Wave
Soldering:
A manufacturing operation in which solder joints are soldered
simultaneously using a wave of molten solder.
|