SMT Terms

A thru L L thru Z


Accelerated stress test A test designed to stress the application until failure.
Acceptable Quality Level AQL. The maximum allowable number of defects per 100 units.
Accuracy The ability to reach the target.
Acoustic Microscopy A non-destructive test method using ultrasonic sound to produce high resolution images.
Active Component Electronic device that actively can change an electrical applied signal (e.g. transistors and IC's)
Adhesive, Conductive is used to form a mechanical and electrical connection as an alternative to soldering.
AIS Adhesive Interconnect System.
Algorithm A specification of actions solving a task.
Alloy A material made by melting two or more metals together.
Antimony Sb. Semi- metal used in some solder alloys.
Antistatic Material Partly conductive material resisting rapid static charging.
AOI Automatic Optical Inspection. Unit inspecting solder paste print or soldered PCB's using vision technology.
AOQ Average Outgoing Quality.
Aperture Opening in a metal stencil or mesh screen.
Aperture file(s) Computer file(s) containing X, Y coordinates, shape and aperture sizes used in the stencil manufacturing process.
AQL Acceptable Quality Level. The maximum allowable number of defects per 100 units.
ASIC Application Specific Integrated Circuit.
Aspect Ratio Stencil thickness to the width of the smallest aperture or PCB thickness to the diameter of the smallest hole.
AXI Automatic X-ray Inspection. Unit inspecting soldered PCB�s using X-ray technology.



Ball Pitch The distance between the centers of two balls on an BGA package.
Bare Board PCB that are not mounted with components.
Bare Die An unpackaged IC (Die).
Bill Boarding Chip component standing on its edge but with both terminals soldered to the solder lands.
Bill of Materials BOM. List of components for a PCBA. Containing reference no. ,part no. and quantities
Bismuth Bi. Metal used in some solder alloys.
BGA Ball Grid Array IC package with solder spheres in an array on bottom side of component base substrate.
BGA Reballing Kit BGA Reballing preforms used to re-attach solder balls to BGA.
BGA Reballing Perform Individual rework perform loaded with solder balls in a pattern mirroring that of the part for re-attaching solder balls to the device reballing perform.
BGA Rework Stencil Mini stencil (StencilQuik) used to repair solder mask underneath BGA while allowing for greater solder volume in the solder joint for great interconnection reliability rework stencils.
BLP Bottom Leaded Packages.
BTAB Bumped Tape-Automated Bonding.
Board Handling Unit Unit convey ring PCBs from one machine to another or turning or flipping the PCB.
Board support Unit or device supporting the printed circuit board from below and preventing warpage. Often used during screen printing and component placement.
BQFP Bumpered Quad Flat Package. IC packages with leads on four sides and corner bumpers.
Bridging (Solder bridging). An unintentional mechanical and electrical short between two component terminals or solder pads.
Bulk Components Loose components . Components delivered in special bulk containers can be supplied to the placement machine using a bulk feeder.
Bulk Feeder Unit used to feed components from bulk containers into the placement machine.



C4 Controlled Collapse Chip Connection.
C5 Controlled Collapse Chip Carrier Connection.
CAD Computer Aided Design. Computer system used to design a product.
CAM Computer Aided Manufacturing. Computer system used to manufacture a product.
CAR Computer Aided Repair. Computer system used to guide product repair.
CAT Computer Aided Test. Computer system used to test a product.
CBGA Ceramic Ball Grid Array. As Ball Grid Array with a ceramic base substrate.
CGA Column Grid Array. As Ball Grid Array with a solder columns as the interconnects..
CCA Circuit Card Assembly.
CDR Convection Dominant Reflow. Reflow soldering where the main heat transfer occurs due to temperature difference.
Centroid A data file containing, as minimum, a list of components with reference designator, coordinates and rotation.
Chemical Tin Or Immersion Tin. Used as protection on PCB solder pads.
Chip Slang expression for a very small component or an integrated circuit.
Chip Shooter Fast SMD placement machine primarily placing small chips.
CIM Computer Integrated Manufacturing.
Circuit Frame A PCB repair tool consisting of copper lead frame which is used to reattach different conductor patterns such as pads and traces to a PCB for repair of same.
Circuit Track A PCB repair tool consisting of thin copper strips which are used to reattach different conductor patterns to a PCB for repair the repair of circuit traces.
COB Chip On Board. An unpacked silicon die placed directly on the PCB and wire bonded.
COF Chip On Flex. Technology where chips are placed and soldered on flexible circuit boards.
Coefficient of Thermal Expansion CTE. The ratio of change in dimension per unit change in temperature.
Component Part. An element of a complete functional unit.
Component Camera A camera in the SMD placement machine used to recognize and measure the position and angle of the picked up components. The vision system then calculate the necessary corrections for an accurate placement on the PCB.
Conductor Electrical connection. E.g. Printed wiring on a PCB.
Conductor Thickness The thickness of a PCB conductor track.
Conductor Width Width of a PCB conductor track.
Controlled Convection Convection heat transferred were temperature, flow, rate and velocity are accurately controlled.
Convection Heat transfer occurring due to temperature difference.
Cool Down Refers to the solder profile period, after reaching the peak temperature, where the solder alloy cools below the point where the alloy solidify again.
Coplanarity The vertical variation of the lead positions on a package.
Copper Cu. Used mainly on PCB's as electrical connections forming the circuit between the components as well in solder.
CPI Continuous Process Improvement.
Cycle Time The time it takes to perform a complete cycle on the process in question.



Discrete Component Defined as separate components in each package.
Delamination (PCB) A separation of the different bonded layers within the PCB.
Delta T Temperature differential.
Desoldering Removal of the solder alloy from a joint.
Dewetting The molten solder repels on the solder pad or component lead. It usually the affected by poor solder-ability.
DCA Direct Chip Attachment.
DFA Design For Assembly.
DFAA Design For Automated Assembly.
DFF Design For Fabrication.
DFM Design For Manufacturing.
DFT Design For Test.
Double Layer PCB Laminate with two layers of conductors forming a circuit pattern.
Double Sided Reflow Soldering A technique were SMC's are placed in solder paste and reflow soldered firstly on one side of the PCB and secondly repeated on the other side. Gravity limits the type of packages that can be used on the first mounted side.
DPM Defects Per Million.
DPMO Defects Per Million Opportunities.
Dross Oxidized solder alloy and contamination laying on top of the molten solder in a wave soldering machine.
Dry-Pack Bags specially designed to MSD storage.
Dry Run An expression for a SMD placement machine running but without actually placing components.
Dummy Component Non-functional component used for placement , hand soldering or rework practice runs.



Edge Conveyor Device transporting and supporting the product (PCB) on its edge.
Edge Repair A type of PCB repair to a damaged edge usually resulting from handling damage to the PCB.
Electronics Manufacturing Services EMS.
Electrostatic Discharge ESD. The transfer of an electrical charge between two objects with different electrostatic potential. Certain electronic components can be very sensitive to ESD.
EMS Electronics Manufacturing Services. An EMS company typically offers manufacturing, test and logistics services for electronic assemblies.
ESD ElectroStatic Discharge. The transfer of an electrical charge between two objects with different electrostatic potential. Certain electronic components can be very sensitive to ESD.
Etched Stencil Thin plate metal plate with hole patterns corresponding to areas where solder or adhesive or underfille will be deposited on a circuit board.
Eutectic Solder Alloy An alloy that changes directly from solid to a liquid state at one exact temperature.



FAC Forced Air Convection. Heat transfer occurring when forcing air over a solid media.
FC Flip-Chip. Refers to bare silicon IC's flipped and attached directly onto the PCB.
Fiducial Camera Camera used to measure the PCB position relative to the placement head.
Fiducial Mark A small mark on the PCB used to calculate the PCB position relative to the placement head. The calculations are then used to ensure precise placement of the components.
Fillet A solder fillet is the build up of solder between the solder land and the component terminal.
Fine Pitch Refers to a short distance between the centers of two leads on an IC. 0.5 mm (20 mil) and down.
Fine Pitch Ball Grid Array FPBGA. See Ball Grid Array.
Fine Pitch Placer A very accurate SMD placement machine capable of placing fine pitch components.
Fine Pitch Quad Flat Package FPQFP or FQFP. Refers to a specific group of fine pitch IC packages with leads on all four sides.
First Pass Yield Yield. Finished units (in percent) not requiring rework.
Flex PCB Flexible (bendable) printed circuit board. Base materials are Polyamide (Kapton) or Polyester (PET), adhesive and conductive foil.
Flip-Chip FC. Refers to bare silicon IC's flipped and attached directly to the PCB.
Flux Chemical mixture usually containing Rosin or synthetic resin (40-50%), activators (20-35%), rheological additives and finally solvents. When heated used to clean component and PCB surfaces for oxides and contaminants.
Flux Activation Temperature The temperature at which the flux starts cleaning component and PCB surfaces for oxides and contaminants.
Fluxer Unit used in a wave soldering machine to apply flux to the bottom side of the PCB.
Foam Fluxer Fluxer unit creating a foam wave of flux by pumping the flux through a porous material. Used in a wave soldering machine to apply flux to the bottom side of the PCB.
Forced Convection Heat transfer occurring when forcing a gas over a solid media.
Foot Length The length of the component lead foot. The part of the lead approximately parallel with the solder pad.
Foot Width Width of the component lead.
Footprint Land Pattern. Refers to the area, pad dimensions and the pattern of pads for a particular component.
Footprint Refers to the floor area a machine takes up.
FPBGA Fine Pitch Ball Grid Array. See Ball Grid Array.
FPQFP Fine Pitch Quad Flat Package. Refers to a specific group of fine pitch IC packages with leads on all four sides.
FPT Fine Pitch Technology. Technology involving components with very short distance between the centres of two leads. From 0.5 mm (20 mil) and down.
FQFP Fine pitch Quad Flat Package. Refers to a specific group of fine pitch IC packages with leads on all four sides.
FR2 Phenol PCB base laminate. Widely used in consumer products.
FR4 Glass epoxy laminate. The most commonly used PCB base material.



Gold (Au) Metal used as protective layer on PCB solder pads, keyboards etc.
Glass Transition Temperature Tg. The temperature below which molecules have very little mobility. On a macro scale PCB laminates are rigid and brittle below their glass transition temperature and can undergo plastic deformation above it.
Global Fiducials Several marks located on the PCB to calculate the PCB position relative to the placement head which are used to precisely place all the components.
Golden Board Known Good Board. Used as reference in electrical testing.
Gull Wing Type of lead style which fleares outward from the component body.



HASL Hot Air Solder Leveling. A hot air knife levels the solder pad finish.
Hot Air Knife System that blows high velocity hot air using the venturi effect. It is used in wave soldering machines immediately after the solder wave to remove excess solder from the PCB.
Hot Air Solder Leveling HASL. Also called HAL. A hot air knife levels the SnPb solder pad finish.



IC Integrated Circuit. Package containing multiple components forming a specific circuit.
ICT Short for In-Circuit Test. Test method where components are tested while connected in a circuit.
Immersion Tin Chemical applied tin. Used as protection on PCB solder pads as a type of board surface finish
Indium In. Metal used in some solder alloys.
Inert Gas Inactive gas such as nitrogen. Nitrogen is used in the soldering process to avoid oxidation of the components, pads and solder alloy.
Infrared IR. Refers to energy (heat) transfer by infrared wave length radiation. Used in some soldering, rework or reflow systems.
Inner Layer A conductive internal layer of a PCB laminate.
Intelligent Feeder A feeder equipped with a microprocessor system designed to avoid set-up and inventory errors.
Intermetalic Layer A relatively thin layer of metal compound formed between two different metals. E.g. between the copper pads and solder alloy used.
IPC (see
IPC TM-50 This standard provides descriptions and illustrations to help users and their customers speak the same language. Also included is a section on acronyms and an index of terms by technology types



J lead Refers to a component with J-shaped leads like a PLCC package.
Joint or solder joint. Mechanical and electrical connection between component terminal and PCB solder pad.



Known Good Board or Golden board. Used as reference board in electrical testing.