EMS Vocabulary

- May 12, 2016-

Active Components: Semiconductor devices, such as transistors and diodes, that can change its basic characteristics in a powered electrical circuit, such as amplifiers and rectifiers.

Automated Test Equipment (ATE): Equipment that automatically tests and analyzes functional parameters to evaluate performance of the tested electronic devices.

Approved vendor list (AVL): listing of all approved sources, in addition to product part descriptions and part numbers.

Ball Grid Array (BGA): A SMD package in which solder ball interconnects cover the bottom surface of the package.

Bill of materials (BOM): a comprehensive listing of all components and sub-assemblies that go into a specific product, showing the quantity of each required to assemble the item or finished product.

Box-build: sometimes, also called systems integration, assembly work other than printed circuit board (PCB) production. The electromechanical assembly process involving enclosure fabrication, installation of sub-assemblies and components, and installation and routing of cabling or wire harnesses.

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.

Clean room: a facility in which environmental elements such as heat, humidity, microbial growth, and user cleanliness are controlled. Used for assembly/packaging of sensitive components or products.

Conformal Coating: A thin layer of material, conductive, magnetic or dielectric, deposited on a substance surface.

Contract manufacturer: an organization that engages in product assembly, engineering services, order fulfillment, product distribution, and aftermarket services. A contract manufacturer usually works on behalf of an OEM. However, some OEMs can also function as contract manufacturers.

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.

Electronics manufacturing services (EMS): an industry based on providing contract manufacturing and product support services on behalf of OEMs. 

Fine Pitch: Fine pitch is more commonly referred to surface-mount components with a lead pitch of 25 mils or less.

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 (FCT): 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.

Gold Finger: The gold-plated terminal of a card-edge connector. Also see Finger.

HDI: High Density Interconnect.

In-Circuit Test (ICT): 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.

Multilayer PCB: Circuit boards consisting four or more layers of printed circuits separated by laminate layers and bonded together with internal and external interconnections.

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 Printed Wiring Board (PWB).

PCB Assembly: The process of positioning and soldering components to a PCB.

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.

RF (radio frequency) and wireless design: A circuit design that operates in a range of electromagnetic frequencies above the audio range and below visible light. All broadcast transmission, from AM radio to satellites, falls into this range, which is between 30KHz and 300GHz.

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.

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: Coating to prevent solder to deposit on.

Test Point: A specific point in a circuit board used for specific testing for functional adjustment or quality test in the circuit-based device.

Testing: A method for determining whether sub-assemblies, assemblies and/or a finished product conform to a set of parameter and functional specifications. Test types include: in-circuit, functional, system-level, reliability, environmental.

Turnkey: A type of outsourcing method that turns over to the subcontractor all aspects of manufacturing including material acquisition, assembly and testing. Its opposite is consignment, where the outsourcing company provides all materials required for the products and the subcontractor provides only assembly equipment and labor.

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.

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