This list of acronyms regularly used in electronic manufacturing services is intended to assist individuals in original equipment manufacturing OEM and electronic manufacturing industries. The EMS acronym list is comprised of manufacturing, engineering, and related technical terms. The scope of this glossary is broad given the range of raw materials, engineering considerations, manufacturing processes, and the numerous acronyms used to represent electronic manufacturing terms.



A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z


AC – Alternating Current

A current that varies with time, commonly applied to a power source that switches polarity many times per second, in the shape of a sinusoidal, square, or triangular wave.

ANOVA – Analysis of Variance

The systematic method of statistically evaluating experimental results to separate the sources of variation.

AOI – Automated Optical Inspection

Automatic laser/video inspection of traces and pads on the surface of inner-layer cores or outer-layer panels. The machine uses cam data to verify copper feature positioning, size, and shape. Instrumental in locating “open” traces, missing features or “shorts”.

AQL – Acceptance Quality Level

The maximum number of defectives likely to exist within a population (lot) that can be contractually tolerable; normally associated with statistically derived sampling plans.

ATE – Automatic Test Equipment

Equipment designed to automatically analyze functional or static parameters to evaluate performance degradation. It may also be designed to perform fault isolation.

ATG – Automatic Test Generation

Computer generation of a test program based solely on the circuit technology, requiring little or no manual programming effort.

AVL – Approved Vendor List

Parts list specifying approved manufacturer and part number with a brief description.


BGA – Ball Grid Array

A packaging technology used to attach integrated circuits to a printed circuit board.

BOM – Bill of Materials

A comprehensive listing of all subassemblies, components, and raw materials that go into a parent assembly, showing the quantity of each required to make the assembly.

BS – Basic Specification

A document that describes the common elements for a set, family or group of products, materials, or services.

BTO – Build-To-Order Systems Assembly

Building and testing of a complete product to a specific customer order, including required peripherals, software, and documentation.


CAD – Computer Aided Design

A system where engineers create a design and see the proposed product in front of them on a graphics screen or in the form of a computer printout or plot. In electronics, the result would be a printed circuit layout.

CAE – Computer Aided Engineering

The interactive use of computer systems, programs, and procedures in an engineering process wherein, the decision-making activity rests with the human operator and a computer provides the data manipulation function.

CAF – Conductive Anodic Filament

Conductive filament formation or metallic electromigration is an electrochemical process which involves the transport of conductive chemistries across a nonmetallic substrate under the influence of an applied electric field.

CAM – Computer Aided Manufacturing

The interactive use of computers systems, programs, and procedures in various phases of a manufacturing process wherein, the decision-making activity rests with the human operator and a computer provides the data manipulation functions.

CapDS – Capability Detail Specification

A document that establishes the specific requirements, noted in a detailed specification, to establish the level of capability that a manufacturer possesses when he has demonstrated that he has met those requirements.

CBGA/CCGA – Ceramic Ball Grid Array/Ceramic Column Grid Array

A grid array packaged component that has ceramic as the substrate of the package and may have either solder balls or solder columns for connections.

CDS – Customer Detail Specification

A document that establishes the specific requirements, noted in a detailed specification, to tailor these to meet the needs of a custom product, material, or service.

CEM – Contract Electronics Manufacturing

Production of electronic equipment on behalf of an original equipment manufacturer (OEM) customer, in which the design and brand name belongs to the OEM. Often refers to the industry based on providing contract design, manufacturing, and related product support services for electronics OEMs. Also referred to as electronics manufacturing services (EMS).

CFT – Customer Focus Team

A team dedicated to the customer under the leadership of a program manager; made up of experts from each functional area of the manufacturing process-supply chain management, design, engineering, manufacturing, and finance and quality assurance. The CFT provides comprehensive project management and close communication throughout the entire product life cycle.

CNC – Computer Numerical Control

A system that utilizes a computer and software as the primary numerical control technique.

Cp – Capability Performance Index

The ratio of the measured performance of a process compared to specified limits.

Cpk – Capability Performance Index

A measure of the relationship between the scaled distance between the process mean value and the closest specification limit.

COB – Chip On Board

A printed board assembly technology that places unpackaged semiconductor dice and interconnects them by wire bonding or similar attachment techniques. Silicon area density is usually less than that of the printed board.

CTB – Capability Test Board

A printed board specifically designed to act as a capability-qualifying component (CQC), or to be used by manufacturer to evaluate process variation, process control, or continuous improvement procedures.

CTE – Coefficient of Thermal Expansion

The linear dimensional change of a material per unit change in temperature.

CTO – Configure-to-Order Systems Assembly

Configuring an already built or partially built product to specific customer requirements and adding specific peripherals and software for individual customer order.

CSP – Chip Scale Package

Active, multi-I/O package that is no larger than 125% of the size of the silicon IC.

CTP – Composite Test Pattern

A grouping of individual test patterns into specific arrangements, to reflect control and precision capability of a manufacturer or manufacturing process.

CTS – Capability Test Segment

A segment or portion of a capability test board (CTB), containing a set or group of individual test patterns (ITP), intended to be used to demonstrate a specific level of printed board complexity or manufacturing capability.

CUSUM Chart – Cumulative Sum Control Chart

A diagram that depicts cumulative deviation from a target.


DC – Direct Current

A current produced by a voltage source that does not vary with time and is normally provided by power supplies, transformers or batteries to power electronic circuits.

DFx – Design For X

The value-added service of instituting “best practices” in the design and new product introduction stages to improve X, where X is manufacturability, testability, mechanical assembly, serviceability, etc

DIM – Data Information Module

A group of records that contain related data that describe a specific function or task.

DIP – Dual In-Line Package

A popular through hole package with leads in rows on opposite sides of the package.

DNC – Distributed Numerical Control

A network that links computer programs or computer-aided systems to numerically controlled machine tools.

DP – Delivered Panel

A production or prototype panel, or portion of either, intended to contain one or more printed boards in a specific arrangement or cluster, to facilitate economic assembly and testing in the next level of manufacturing.

DRAM – Dynamic RAM

Read-write memory that must be refreshed (read or written into) periodically to maintain the storage of information.

DS – Detailed Specification

A document that describes the exact requirements for a specific product, material, or service.

DUT – Device Under Test

Component, PCB, or assembly subjected to a test. Also known as unit under test (UTT) and loaded board.


EDI – Electronic Data Interchange

The electronic transfer of data over a network.

EMI – Electromagnetic Interference

Unwanted radiated electromagnetic energy that couples into electrical conductors.

EOL – End Of Life

Term applied to products or components that are being retired from the market because of technology obsolescence or rapidly declining demand.

ERP – Enterprise Resource Planning

Describes software systems designed to manage most or all aspects of a manufacturing or distribution enterprise (an expanded version of MRP systems). ERP systems are usually broken down into modules such as Financials, Sales, Purchasing, Inventory Management, Manufacturing, MRP, and DRP. The modules are designed to work seamlessly with the rest of the system and should provide a consistent user interface between them. These systems usually have extensive set-up options that allow you to customize their functionality to your specific business needs. Unfortunately, in the real world, ERP systems rarely are sufficient to meet all business needs and a myriad of other software packages such as Customer Relationship Management (CRM), Manufacturing Execution Systems (MES), Advanced Planning and Scheduling (APS), Warehouse Management Systems (WMS) and Transportation Management Systems (TMS) are being sold to make up for these deficiencies.

ERS – Equivalent Series Resistance

A loss parameter used to compare two capacitors of equal value to determine their relative effectiveness as filters.

ESD – Electrostatic Discharge

A transfer of electrostatic charge between bodies at different electrostatic potentials caused by direct contact or induced by an electrostatic field.

ESS – Environmental Stress Screening

A process which applies specific kinds of environmental stresses to products on an accelerated basis, but within their design parameters and limits to precipitate latent and intermittent flaws to detectable failures.


FA & T – Final Assembly and Test

The process comprising a subset or all these manufacturing steps: fabricating and assembling the mechanical components and subassemblies of the final product, assembling one or more printed-circuit board (PCB) assemblies and other components into a subassembly, integrating all PCB assemblies and subassemblies into a finished product, testing, and preparing for shipping. Also, commonly referred to as “final assembly and test (FA&T)” or “system assembly and test (SA&T)”.

FEA – Finite-Element Analysis

A computer-based analysis method that subdivides geometric entities into smaller elements and links a series of equations to each element so that they can then be analyzed simultaneously.

FEM – Finite-Element Modeling

The use of a model to represent a problem that can be evaluated by finite-element analysis.

FP – Flat Pack

A low-profile IC package, which typically has gull wing type of leads on two or four sides.

FPT – Fine-Pitch Technology

A surface-mount assembly technology with component terminations on less than 0.625-mm (0.025-inch) centers.


G10 –

A laminate consisting of woven epoxy-glass cloth impregnated with epoxy resin under pressure and heat. G10 lacks the anti-flammability properties of FR-4. Used mainly for thin circuits such as in watches.

GS – Generic Specification

A document that describes as many general requirements as possible, pertaining to a set, family or group of products, materials, or service.


HASL – Hot Air Solder Leveling

A method of coating exposed copper with solder by inserting a panel into a bath of molten solder then passing the panel rapidly past jets of hot air.

HDI – High Density Interconnect

Ultra-fine geometry multi-layer PCB constructed with conductive microvia connections. These boards also usually include buried and/or blind vias and are made by sequential lamination.


IC – Integrated Circuit

A small, complete circuit made by vacuum deposition and other techniques, usually on a silicon chip, and mounted in a package.

ICT – In-Circuit Test

Combination of hardware and software that identifies manufacturing induced faults of printed circuit board assemblies (PCBAs) by isolating and individually testing devices using a bed-of-nails fixture. Potential faults include shorts, opens, wrong components, missing components, etc.

ILB – Inner-Lead Bond

The connection between a conductor on a bonding tape and a bare die.

IMB – Intermetallic Bond

Thin layer of chemical bonding in metals.

IMC – Intermetallic Compound

Metallic compounds that form at the interfaces between different metals, such as copper-tin compounds that form at the interface of a solder joint and a copper lead. IMCs typically have significantly different properties, such as tensile strength.

IPC – The Institute for Interconnecting and Packaging Electronic Circuits

The global trade association serving the printed board and electronics assembly industries, their customers and suppliers.

IR – Infrared Reflow

Re-melting of solder using infrared heating as the primary source of energy.

ITP – Individual Test Pattern

A single test pattern designed and intended to serve a specific evaluation technique for determining an aspect of a manufacturer or manufacturing process capability.

ITS – Individual Test Specimen

A single test specimen that contains an individual test pattern (ITP) and is used to determine an aspect of a manufacturer or manufacturing process capability.

ITT – Inter-Test Time

The duration between two successive driver strobes.


JEDEC – Joint Electronic Devices Engineering Council

A part of the Electronic Industries Association (EIA) that publishes specifications and standards for electronic components.

JIT – Just-In-Time

Production control techniques that minimize inventory by delivering parts and material to a manufacturing facility just before they are incorporated into a product.

J-Leads –

The preferred surface mount lead form used on PLCCs, so named because the lead departs the package body near its Z axis centerline, is formed down then rolled under the package. Leads so formed are shaped like the letter “J”.


KGA – Known Good Assembly

A correctly operating printed board assembly that serves as a standard unit by which others can be compared.

KGB – Known Good Board

A correctly operating PCB. It is used in learning or debugging a test program in development and for comparison testers where it serves as the standard unit by which other PCBs are compared.


LCCC – Leadless Ceramic Chip Carrier

A hermetically sealed ceramic package that has pads (castellations) around its sides for solder connection in a surface mounting application.

LMC – Least Material Condition

The condition in which a feature of size contains the least amount of material within the stated limits of size.

LPI – Liquid Photo-Imageable Solder Mask

An ink that is developed off using photographic imaging techniques to control deposition. It is the most accurate method of mask application and results in a thinner mask than dry film solder mask. It is often preferred for dense SMT. Application can be spray, curtain coat or squeegee.

LSI – Large-Scale Integration

An integrated circuit with over 100 gates.


MCM – Multichip Module

A circuit comprised of two or more silicon devices bonded directly to a substrate by wire bond, TAB or flip chip.

MELF – Metal Electrode Face Bonding

A cylindrical leadless component with a round body and metals terminals on the ends.

MES – Manufacturing Execution System

Software systems designed to integrate with enterprise systems to enhance the shop-floor-control functionality that is usually inadequate in ERP systems. MES provides for shop floor scheduling, production and labor reporting, integration with computerized manufacturing systems such as automatic data collection and computerized machinery.

MMC – Maximum Material Condition

A drawing defining certain characteristics of the printed board, such material within the stated limits of size.

MRP – Materials Requirement Planning

A set of techniques that uses bill of material data, inventory data, and the master production schedule to calculate requirements for materials.

MTBF – Mean Time Between Failures

The arithmetic or statistical mean average time interval, usually in hours, that may be expected between failures of an operating unit. Results should be designated actual, predicted, or calculated.


NC – Numerical Control

The use of mathematics to define, design or test geometric quantities that are used in a computer-aided technology.

NC Drill – Numeric Control Drill Machine

A machine used to drill the holes in a printed board at exact locations, which are specified in a data file.

NMR – Normal-Mode Rejection

The amount of noise superimposed on the input signal of a direct-current (DC) digital voltmeter that the instrument is capable of rejecting.

NPI – New Product Introduction

The process of bringing a product or service from inception to market. Pre-release steps are generally referred to as New Product Development, and the release to manufacturing and market steps are referred to as New Product Introduction.


OA – Organic Aqueous

Water soluble flux.

OEM – Original Equipment Manufacturer

The company behind the “brand name” of a product that traditionally designed, manufactured, marketed, and provided customer support for their products. Increasingly, one or more of these activities are being outsourced to EMS companies. Examples of OEMs include IBM, Hewlett-Packard, Cisco, Sun Microsystems, Sony, Fujitsu, Siemens, Philips, and many others.

OLB – Outer-Lead Bond

The connection between a conductor on a bonding tape and the base material.

OSP – Organic Solder Preservative

Layers of organic coatings applied to entire board surfaces to prevent oxidation and to retain solderability.


PB – Printed Board

The general term for completely processed printed circuit and printed wiring configurations. (This includes single-sided, double-sided and multilayer boards with rigid, flexible, and rigid-flex base materials.)

PBGA – Plastic Ball Grid Array

A ball grid array component whose package substrate is made of plastic, most likely an FR-4 equivalent of epoxy-fiberglass, polyimidearramid, or similar resin-fiber combinations.

PCA – Printed Circuit Assembly

The generic term for a PCB after all electrical components have been attached. Also referred to as a printed wiring assembly (PWA).

PCB – Printed Circuit Board

A part manufactured from a rigid base material upon which a completely processed printed circuit has been formed.

PCBA – Printed Circuit Board Assembly

Second-level integration of active and passive devices (electrical, electronic, optical and/or mechanical) on a rigid substrate.

PCMCIA – Personal Computer Memory Card International Association

The organization that has developed the early standards for the various sizes of modules which were initially for memory expansion but are now used for many different electronic functions.

PGA – Pin Grid Array

Like a pin grid array. An IC package that has solderable connections in a grid layout on the bottom of the package and is soldered to the surface of the substrate (PWB) with butt solder joints.

PLCC – Plastic Leaded Chip Carrier

A plastic IC package for surface mounting applications that has leads, generally “J” leads, on all four sides.

PP – Production Panel

An arrangement of printed boards fabricated from laminate or base materials as a group in a specific cluster to facilitate economic fabrication techniques using controlled and documented chemical, mechanical and electrical processes.

PPB – Production Panel

A printed board fabricated from laminate or base materials in an environment that consists of controlled and documented chemical, mechanical and electrical processes used in combination to produce the features and characteristics of the final printed board product.

PQFP – Plastic Quad Flat Pack

An FP with leads on four sides generally refers to a plastic quad flat package that is built to JEDEC standards.

PTH – Pin-Through-Hole or Plated-Through-Hole

A method of obtaining electrical connection between components and substrate by soldering component leads (or pins) inserted in plated through-holes.

PRD – Product Requirements Document

a product requirements document commonly referred to as a PRD is a document that describes the product that you’re about to design. It defines the capabilities that must be included for the product to be considered complete.

PWA – Printed Wiring Assembly

The generic term for a PWB after all electrical components have been attached.

PWB – Printed Wiring Board

The substrate, generally epoxy glass, used to provide component attachment lands and interconnections to form a functioning electronic circuit (also called a PCB or printed circuit board).


QFP – Quad Flat Pack

A FP with leads on four sides. Generally, refers to a plastic quad flat package that is built to JEDEC standards.

QSOP – Quarter-Size Small Outline Package

An SO style IC package that has leads on a 25-mil pitch. The name derives from the fact that the package is approximately ¼ the length and ¼ the width of a standard SOIC, and thus a package of the same pin count occupies approximately ¼ the area on a PWB.


RAM – Random Access Memory

A type of memory that offers access to storage locations within it by means of X and Y coordinates.

ROM – Read Only Memory

A random-access storage in which the data pattern is unchangeable after manufacture.

RMF – Risk Management Factor

The maximum tolerable percentage of possible defects within a lot (group) of units, based on approximately 95% confidence level.


SA & T – Systems Assembly and Test

The process comprising a subset or all these manufacturing steps: fabricating and assembling the mechanical components and subassemblies of the final product, assembling one or more printed-circuit board (PCB) assemblies and other components into a subassembly, integrating all PCB assemblies and subassemblies into a finished product, testing, and preparing for shipping. Also, commonly referred to as “final assembly and test (FA&T)” or “system assembly and test (SA&T)”.

SIG – Sigma

The lowercase Greek letter that is used to designate a standard deviation of a population.

SIP – Single-Inline Package

A component package with one straight row of pins or wire leads.

SIR – Surface Insulation Resistance

The electrical resistance of an insulating material between a pair of contacts, conductors or grounding devices in various combinations, that is determined under specified environmental and electrical conditions.

SMA – Surface Mount Assembly

An electronic assembly or module that is manufactured with surface mounted components and using surface mount technology.

SMC – Surface Mount Component

A leaded or leadless device (part) that is capable of being attached to a printed board by surface mounting.

SMT – Surface Mount Technology

A method of attaching electrical components directly to a board substrate rather than through a plated hole.

SMOBC – Solder Mask Over Bare Copper

A method of fabricating a printed circuit board that results in final metallization being copper with no protective metal. The non-coated areas are coated by solder resist, exposing only the component terminal areas. This eliminates tin lead under the mask.

SMT – Surface Mount Technology

The technology used to manufacture electronic assemblies using components that are soldered directly to the surface of the substrate or PWB.

SO – Small Outline

A package resembling a flat pack with leads on only two sides.

SOIC – Small Outline Integrated Circuit

A plastic IC package for surface mounting applications that has leads on two opposites sides.


A plastic IC package with “J” leads on two sides. It resembles a plastic DIP or an SOIC except for lead spacing and forming.

SOL/SOW – Small Outline-Large/Small Outline Wide

SO generally refers to a package that is approximately 150 mils wide, while SOL/SOW refers to packages that are approximately 300 mils wide.

SOP  – Small Outline Package

Another designation for the small outline ICP packages, i.e. Small Outline Package (Very Small Outline Package, Shrink Small Outline Package).

SOT – Small Outline Transistor

A plastic leaded package for diodes and transistors used in surface mounting applications.

SPC – Statistical Process Control

The use of statistical techniques to analyze a process or its output to determine any variation from a benchmark and to take appropriate action to restore statistical control, if required.

SQC – Statistical Quality Control

The use of statistical techniques to document and assure end product compliance with requirements.

SS – Sectional Specification

A document that describes the specific requirements pertaining to a portion of a set, family, or group of products, materials or, services.

SSOIC – Shrink Small Outline IC

An SO style IC package that has leads on a 25-mil pitch.


TAB – Tape Automated Bonding

An IC interconnection process that uses organic tape to support pre-formed leads during bonding to the chip (inner lead bonding-ILB) and connection to the substrate (outer lead bonding-OLB). The IC chip is usually bare during the interconnecting processes.

TBGA – Tape Ball Grid Array

A ball grid array component package that uses TAB techniques to make the connections between the IC chip and the solder balls. This results in a solder ball grid array that is only around the periphery and leaves compliant connections between the IC and the solder balls for better TCE reliability.

TCE – Thermal Coefficient of Expansion

The rate of expansion (ppm/C) of a material when its temperature is increased.  Also referred to as Coefficient of Thermal Expansion.

TG – Glass Transition Temperature

The point at which rising temperatures cause resin inside the solid base laminate to start to exhibit soft, plastic-like symptoms. This is expressed in degrees Celsius (°C).


UBGA – Micro BGA

Micro BGA .8mm ball spacing or less.

UL – Underwriter’s Laboratories, Inc.

A corporation supported by some underwriters for establishing safety standards on types of equipment or components. Their logo shows applicable UL certification.


VFP – Very Fine Pitch

The center-to-center lead distance of surface mount packages that are between 0.012 inch and 0.020 inch

VLSI – Very Large Scale Integration

Integrated circuits with more than 80,000 transistors on a single die that are interconnected with conductors that are 1 micron or less in width.

VSOIC – Very Small Outline IC

A SO style IC package that has leads with a pitch of 30 mils or less.


WIP – Work-In-Process

Generally, describes inventory that is currently being processed in an operation, or inventory that has been processed through one operation and is awaiting another operation. WIP is an inventory account that represents the value of materials, labor, and overhead that has been issued to manufacturing but has not yet produced a stock-able item. Depending on how your accounting and inventory systems are set up, it may also include components picked for production usage or finished products awaiting final inspection.


X-Axis –

The horizontal or left-to-right direction in a two-dimensional system of coordinates. (This axis is perpendicular to the Y-axis.)


Y-Axis –

The vertical or bottom-to-top direction in a two-dimensional system of coordinates.


Z-Axis –

The Axis perpendicular to the plane formed by the X and Y datum reference. This axis usually represents the thickness of the boards.