PCB Glossary starting with D
Date Code: Marking of products to indicate their date of manufacture. ACI standard is WW/YY(weekweek/yearyear)
Datum: The theoretically-exact point, axis or plane that is the origin from which the location of geometric characteristics of features of a part are established.
Deburring: Process of removing burrs after PCB drilling.
Decal: A graphic software representation of a component, so named because hand tape-up of printed circuit boards employed the use of pull-off and paste decals to represent components. Also called a part, footprint or package . On a manufactured board the body of a footprint is an epoxy-ink outline.
Defect: Any nonconformance to specified requirements by a unit or product.
Definition: The fidelity of reproduction of pattern edges, especially in a printed circuit relative to the original master pattern.
Delamination: A separation between any of the layers of the base of laminate or between the laminate and the metal cladding originating from or extending to the edges of a hole or edge of board.
Design For Manufacturability (DFM): The front-end process for electronic products which focuses on minimizing the cost, complexity, defects and production time of the product-specific volume manufacturing process.
Design Rule: Guidelines that determine automatic conductor routing behavior with respect to specified design parameters.
Design Rule Checking: The use of a computer program to perform continuity verification of all conductor routing in accordance with appropriate design rules.
Desmear: The removal of friction-melted resin and drilling debris from a hole wall.
Device: Any type of electrical component on a PC board. It will have functions and properties unique to its type. In a schematic (and the extracted BOM ) , it will be labeled with a value or device number. There are two main classes of devices, passive and active. .
Dewetting: A condition that results when molten solder has coated a surface and then receded, leaving irregularly shaped mounds separated by areas covered with a thin solder film and with the base material not exposed.
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 which occupies the region between two conductors.
Digitizing: The converting of feature locations on a flat plane to a digital representation in X-Y coordinates.
Dimensional Stability: A measure of the dimensional change of a material that is caused by factors such as temperature changes, humidity changes, chemical treatment, and stress exposure.
Dimensioned Hole: A hole in a printed board whose location is determined by physical dimensions or coordinate values that do not necessarily coincide with the stated grid.
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.
Double-Sided Board: A printed board with a conductive pattern on both sides.
DRC: Design rule check.
Dry-Film Resists: Coating material specifically designed for use in the manufacture of printed circuit boards and chemically machined parts. They are suitable for all photomechanical operations and are resistant to various electroplating and etching processes.
Dry-Film Solder Mask: Coating material (dry-film resist) applied to the printed circuit board via a lamination process to protect the board from solder or plating.
Dynamic Random Access Memory (DRAM): Dynamic Random Access Memory (DRAM) is the most commonly used type of volatile memory for the main memory in computing devices.
PCB Glossary starting with E
ECL —Emitter Coupled Logic: A type of unsaturated logic performed by emitter-coupled transistors. Higher speeds may be achieved with ECL than are obtainable with standard logic circuits. ECL is costly, power hungry, and difficult to use, but it is four times faster than TTL. [Graf]
Edge Clearance: The smallest distance from any conductors or components to the edge of the 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.
Electroless Copper: A thin layer of copper deposited on the plastic or metallic surface of a PCB from an autocatalytic plating solution (without the application of electrical current).
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 electro deposition of an adherent metal coating on a conductive object. The object to be plated is placed in an electrolyte and connected to one terminal of a D.C. voltage source. The metal to be deposited is similarly immersed and connected to the other terminal.
Enclosures: The high-precision, close-tolerance housings which encase electronics products and assemblies. Typically constructed from various metals and plastics, enclosures are an integral part of electronics products and are critical for protection, environmental control, interconnection, compactness and multi-unit integration.
Environmental Stress Screening: Environmental Stress Screening is a process for the detection of early life defects in which components or assemblies are tested at the temperature and voltage extremes of their normal operating conditions for extended periods.
Epoxy: A family of thermosetting resins used in the packaging of semiconductor devices. Epoxies form a chemical bond to many metal surfaces.
Epoxy Smear: Epoxy resin which has been deposited on edges of copper in holes during drilling either as uniform coating or in scattered patches. It is undesirable because it can electrically isolate the conductive layers from the plated-through-hole interconnections.
ESR: Electro-statically applied Solder Resist.
Etchback: The controlled removal of all components of the base material by a chemical process acting on the sidewalls of plated-through holes to expose additional internal conductor areas.
Etching: The chemical, or chemical and electrolytic, removal of unwanted portions of conductive materials.
PCB Glossary starting with F
Fab: Fabrication.
Fabrication drawing: A drawing used to aid the construction of a printed board. It shows all of the locations of the holes to be drilled, their sizes and tolerances, dimensions of the board edges, and notes on the materials and methods to be used. Called "fab drawing" for short. It relates the board edge to at least on hole location as a reference point so that the NC Drill file can be properly lined up.
Fiducial Mark: A printed board feature (or features) that is created in the same process as the conductive pattern and that provides a common measurable point for component mounting with respect to a land pattern or land patterns.
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.
First Article: A sample part or assembly manufactured prior to the start of production for the purpose of assuring that the manufacturer is capable of producing a product that will meet specified requirements.
Flash: Flash is a densely packable, relatively inexpensive type of nonvolatile memory, which can be modified electrically, often while in a circuit. Flash architecture generally assumes that it will be read often but seldom written to.
Flex Circuit Assembly: Flex Circuit Assembly is an advanced process of attaching electrical components to a flexible circuit. Flex circuits are utilized in compact devices with mobile mechanical assemblies such as wireless devices and data storage systems.
Flip Chips: Flip Chips are structures that house circuits interconnected face down directly to the substrate with solder bumpers without leads, and are utilized to minimize printed circuit board surface area when compact packaging is required.
Flux: The material used to remove oxides from metal surfaces and enable wetting of the metal with solder.
Flying Probe: A type of bare board electrical test machine that uses probes on the ends of mechanical arms to locate and touch the pads on the board. The probes move quickly across the board verifying continuity of each net as well as resistance to adjacent nets.
Footprint: geometry of pads for soldering certain electronic component.
FR-1: A paper material with a phenolic resin binder. FR-1 has a TG of about 130°C.
FR-2: A paper material that is similar to FR-2 - except that an epoxy resin is used instead of phenolic resin as a binder. Used mainly in Europe.
FR-3: The UL-designated rating for a laminate composed of glass and epoxy that meets a specific standard for flammability. FR-4 is the most common dielectric material used in the construction of PCBs.
FR4: Flame Retardant 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.
