PCB Glossary

The intention of this glossary is to explain the most commonly used terms and abbreviations that come up in PCB documents and daily business transactions. This glossary is not complete by any means but intention is to cover the most usual ones. For more comprehensive view of PCB related technical terms, please see the IPC standard IPC-T-50, Terms and Definitions for Interconnecting and Packaging Electronics Circuits. There may be some individual mismatches between this glossary and IPC standard as this glossary tries to match closely to everyday language of our business.

AOI Automatic Optical Inspection, method of inspecting pattern of any layer in PCB
Aspect Ratio AR, relation of PCB thickness divided by nominal size of the plated hole, is related to the capability of drilling and plating
Buried via Mechanically drilled plated hole which starts and ends inside the PCB , for example via between layers 2 and 7 in some 8 layer PCB
BGA Ball Grid Array, commonly used surface mount package for ICs
CAD Computer Aided Design, design of the circuitry and features of the PCB, outputs graphical data (Gerber files) or database (ODB++)
CAM PCB document checking and handling step and 1st process step in PCB manufacturing, checks and modifies customer files to PCB manufacturing documents
DS Double-sided PCB, has 2 conductive layers (Top and Bottom)
DDU Delivered Duty Unpaid, a delivery term where supplier takes care of transportation, see details in Incoterms 2010
EAU Estimated Annual Usage in pieces, usually forecasted by customer
ENIG Electroless Nickel Immersion Gold, metallic solderable surface finish for component contact areas and for mechanical contacts like keypad or spring loaded contact
ET Electrical Test, test for PCB electrical contacts
ETA Estimated Time of Arrival
ETD Estimated Time of Delivery
FCA Free Carrier, a delivery term , for example FCA Oulu means that supplier in Oulu will give the goods to the transportation company organized by customer, see details in Incoterms 2010
Floor life max allowable time between opening vacuum package and the soldering of the PCB (see also MSL)
FPC Flex PCB, designed and manufactured for flexible assembly or dynamic flexible application
FQC Final Quality Control
FR4 FR= Flame Retardant, FR4 is one of UL classifications of most commonly used PCB dielectric material, mixture of epoxy resin and glass cloth (possibly also some fillers)
Gerber Commonly used format for PCB manufacturing files, most commonly extended gerber RS-274X, also sometimes used as a name of complete PCB file package (including also drawings, specification files, drill files, netlist and other necessary documents)
HASL Hot Air Solder Levelling, metallic solderable surface finish for component contact areas, consist of Sn-Ag (lead-free, such as CN100) or Sn-Pb (leaded)
HDI High Density Interconnection, a PCB having laser vias and overall high packaging density
Impedance control Controlling impedance in PCB manufacturing, Impedance is an electrical property of a transmission line in PCB, for example 50ohm +/-10%
IC Integrated Circuit, a silicon chip containing the functionality of electronic component
IPC Association Connecting Electronics Industries, a trade association providing PCB standards and other useful resources for PCB and Electronics industry
IPC Class2 Most commonly used quality standard for PCBs, based on IPC standards IPC-6011 and IPC-6012 (rigid PCB), specifies requirements for finshed PCBs, Class2 is a performance class for ‘dedicated service electronics products’
IPC Class 3 Commonly used quality standard for PCBs, based on IPC standards IPC-6011 and IPC-6012 (rigid PCB), specifies requirements for finshed PCBs, Class3 is a performance class for ‘high reliability electronics products’ (this classification has usually cost impact)
Laser via A plated via hole that has been drilled by laser (CO2 or UV or combined), typically between only 2 layers, for example diameter 100u hole between layer1 to layer2
LDI Laser Direct Imaging, a method for exposing PCB pattern in excellent accuracy by laser beam (no films needed)
LPI, LPISM, LPISR Liquid Photoimageable solder mask, Liquid Photoimageable solder resist
Microvia Synonym of laser via (by IPC include also possibility of small via by mechanical drilling or photovia but most commonly understood as laser via)
Mil 1/1000 of an inch, 25,4um, widely in use  (thou is synonym to mil),  For example 4 mils wide line is 100u wide
ML Multilayer PCB, having more than 2 conductive layers
MOT Maximum Operating Temperature
MSL  Moisture Sensitivity Level, defines the max floor life and soldering conditions, see details in standard IPC/JEDEC J-STD-020  (Rigid PCBs are mostly close to MSL3 in lead-free soldering)
MOQ Minimum Order Quantity (in pieces), defined the minimun possible order quantity in pcs for certain price
MOV Minimum Order Value (in currency), defines the minimum possible order value
NPTH Non-Plated Through Hole, mechanically drilled hole through the PCB, no copper plating
ODB++ PCB document database including all necessary data for PCB manufacturing
OSP Organic Solder-ability Preservative, organic solderable surface finish to cover component contact areas (Cu)
OZ Ounce, is fairly commonly used to define nominal copper thickness in non-plated PCB layers, for example 1 oz = 35u; 1/2 oz = 18u
PCB Printed Circuit Board, non-populated board that provides point-to point connections between electrical components
PCBA Printed Circuit Board Assembly, PCB with populated electrical components
PP Prepreg
Prepreg An adhesive layer between conductive layers (bond ply) in ML stack-up, usually will turn to the same laminate material during the bonding process, for example FR4 prepreg will become FR4 laminate after pressing
PTFE PolyTetraFluoroEthylene, Teflon, dielectric material for some RF PCBs
PTH Plated Through Hole, a copper plated hole that connects PCB layers to each other, can be also for component assembly (component hole like pressfit hole)
PWB Printed Wiring Board, synonym to PCB (IPC defines a slight difference)
QC Quality Control
QFP Quad Flat Pack is a commonly used SMT IC package that has leads in all 4 sides
QTA Quick Turn-Around, express delivery, leadtime below standard leadtime
RCC, RCCu Resin Coated Copper foil, dielectric for layers for laser drilling, max 75u thick, only epoxy resin (no glass)
RFQ Request For Quotation
RoHS Restriction of Hazardous Substances, EU directive 2002/95/EC, resitricting the use of lead for example, RoHS compliant means that the part fullfills the RoHS directive and meet the leadfree soldering process requirements
Setup cost see startup cost
Startup cost One-time cost for a new revision of the PCB, covers the tooling and documentation cost, does not occur in repeat orders with the same revision of documents
SIT Secondary Imaging Technology, combination of 2 different solderable surface finishes,  typically combination of OSP and ENIG in the same PCB
Shelf life Time that PCBs can be stored in none-opened vacuum package without compromizing use-ability of the product
SM Solder Mask, also solder resist, permanent coating material on PCB, covering the areas of PCB that will be not soldered (most commonly green, other colors also)
SMT Surface Mount Technology
SPC Statistical Process Control
Tooling cost See startup cost
UL Underwriters Laboratory, a testing organisation for fire safety and classification of PCB like UL94V-0 (flammability and MOT ratings of PCB materials, technologies and manufacturers)
WD, working day Working day is an unit used to describe delivery time, it exludes days off like Saturday, Sunday and public holidays, for example 10wd means usually delivery time of 2 weeks (2×5 days/week)