*µBumps: Smaller copper pillars.  

*300mm Bumping: Copper pillar plating across a whole 300 mm wafer. 

*Advanced Packaging: Next generation of Packaging. Akin to HDI for PCB’s.  

*AMARO: Automated Microelectronics Analysis and Reporting.  

Annular Ring: This term refers to the copper pad area that is left after a hole is drilled through it. This ring is measured from the edge of the pad to the edge of the hole and is an important consideration in PCB design, as it allows an electrical connection to be made from one side of the hole to the other.

Anti-Solder Ball: This type of technology is commonly applied in SMT production lines with the goal of limiting the amount of tin involved in the stencil process. This is done by making a stencil on the board and creating openings at places where the solder ball tends to be produced so that the tin paste will flow to the openings.

AOI: Short for automated optical inspection, AOI refers to a type of inspection method used to find potential problems concerning soldering performance in multi-layer PCBs with components mounted on. The AOI equipment finds these issues by capturing images of the inner PCB surfaces, looking for any possible issues in terms of displacement, polarity etc.

AQL: Short for acceptance quality limit, AQL refers to the acceptable number of defective boards produced within a production run.

Array: This word refers to the combination of multiple copies of the same PCB into a connected matrix of boards. An array may also be referred to as a panelized, stepped out, or palletized PCBs. By assembling boards this way, the assembly process can be completed much more quickly. The Array # Up, in turn, refers to how many PCBs are included in the array.

*ASA: American Semiconductor Academy. 

Aspect Ratio: Aspect ratio refers to the ratio between a PCB's thickness and diameter of its minimum drilled hole. It's best to keep aspect ratios low to improve plating quality and minimize potential plating or other hole quality failures.
Assembly Drawing: An assembly drawing is a reference depicting the assembly requirements of a PCB. These drawings will usually include the placements of components as well as the construction technologies, methods, and parameters needed to make it happen.

*Build-Up Film: Material used to sequential add layers to a given design.

*Bumping: Plating copper pillars onto advanced package or wafer.  

Buried Resistance Board: The term refers to a printed circuit board with resistors buried inside. This design improves the integrity of resistant components to improve the overall function and reliability of the PCB.

Buried Via: A buried via is a through-hole that connects inner layers, but it can't be seen from the exterior of the PCB because it is buried inside the board.

CAD: An acronym for computer-aided design, CAD refers to a designer's use of computer and pattern equipment to develop and implement a PCB layout. The result is a three-dimensional graphic of the design, which, in this case, is the layout of a PCB.

CAE: An acronym for computer-assisted engineering that refers to schematic software packages used to develop and visualize PCB designs.

CAM Files: CAM is an acronym for computer-aided manufacturing, and the files produced by this software are used for PCB manufacturing. There are multiple types of CAM files, including Gerber files for photoplotters and NC Drill files for NC Drill machines. These files are usually sent off to board and assembly houses for refinement and eventual manufacturing.

Carbon Mask: This is a type of conductive carbon paste that is added to the surface of a pad. Made with a combination of resin and carbon toner, carbon masks are heat-cured and are typically applied to jumpers, keys, etc.
Ceramic Substrate Printed Board: This type of board is made with a ceramic substrate, to which other materials are bonded with alumina or aluminum nitride. The primary selling points for ceramic substrate boards are their excellent insulation capabilities, thermal conductivity, soft solderability, and adhesive strength.

*Chiplets: Cut up a monolithic die into many smaller dies. Increased yield, allows for rapid silicon customization. Often referred to as Die Disaggregation.  

Circuit: It refers to a conductive loop composed of metal leads and electronic components. It falls into one of two categories: DC circuits and AC circuits.

COB: Shorthand for chip-on-board, this term is a type of bare chip SMT technology. COB involves directly mounting integrated circuits to a PCB instead of packaging them first. Common in mass-produced gadgets and toys, COB can be identified by a black glob of plastic on a PCB, called a glob top. Underneath the glob, the chip connects to the board with fine wires.

Component Hole: This is a plated hole in a PCB that is made for a component. These holes are intended to facilitate either a component pin, termination, or wire with an electric connection.
Component Side: This refers to the side of a PCB that contains components. The opposite side contains soldering points for components.

Component: Alternatively called electronic components or parts, components are basic pieces that can be used to build electronic equipment and devices. Examples include resistors, capacitors, potentiometers, valves, radiators, etc.
Connector: This term refers to a transmitting component that connects two or more active components in an assembly. Usually, connectors consist of a plug and receptacle, which can be easily joined and separated.

Copper Weight: This term is used to indicate the thickness of copper foil on each layer of a PCB. It's typically expressed in ounces of copper per square foot.

Counterbored Holes: These cylindrical holes are meant to be used with a fastener so that the fastener sits flush with the PCB surface.

Countersink Holes: These are cone-shaped holes that are drilled into a PCB. To allow a countersunk screw to sit flush with the PCB surface.

Cutout: This is a groove or shape that is routed into a PCB, creating empty space on the PCB.
Daughter Board: The "daughter" of a "mother" board, a daughter board contains plugs, pins, sockets, and connectors and plays a big role in internal connections for electronic devices and computers.

Double-Sided PCB: A type of PCB that features traces and pads on both sides, rather than a single side.
DRC: An acronym for design rule check, this is a software verification of a PCB layout. These are often used on PCB designs before production to ensure the design doesn't contain any potential sources of error like small drill holes or traces placed too close together.

Drill Hits: This is another way to refer to how many holes are drilled on a PCB or where holes will be drilled in a PCB design.

Dry Film Solder Mask: This is a type of solder mask film that is applied to a printed board that results in a higher resolution mask with finer line designs. This method tends to be more expensive than liquid solder masks.

*DTCO: Design/Technology Co-Optimization. 

Edge Connector: This type of connector is designed for the edge of a PCB, and it is most often used to facilitate an add-on card.

Edge Plating: This is a term used for copper plating that stretches from the top to the bottom of a surface and along the edges of a board, allowing for edge soldering and connections.

*EMIB: Embedded Multi-die Interconnect Bridge. 

External Layer: Also called an outer layer, an external layer is a layer on the outside of copper to which components attach.

*F2F µBumps: Face-to-Face Bumps. Smaller Copper Pillar Bumps are used to connect disaggregated dyes.
Fabrication Drawing: This drawing is a way for designers to communicate a PCB design to engineers and workers. It will typically include an illustration of the board, locations, information about holes to be drilled, notes about the materials and methods involved, etc.

*FDI: Foverous Die Interconnect.  

Fine Pitch: This term refers to a class of chip packages with micro-spacing between leads, typically below 0.050 inches.

Finger: These are metal pads found along the edge of a board. These are typically used when trying to connect two circuit boards together to expand the capacity of a computer, for example.

First Article: This is what the first manufactured board is called. First articles are usually produced in small groups before volume production begins so that designers and engineers can inspect the product for potential errors or performance problems.

*FO-PLP: Fan Out Panel Level Placement.

*FO-WLP: Fan Out Wafer Level Packaging.  

*FPGA: Field Programmable Gate Array. (Programable silicon transistors) 

FR4: This is a material rating for a flame-resistant material. It also refers to the most commonly used PCB substrate material. The name specifies that the resin material is capable of automatically extinguishing when it is aflame.
Gerber File: A type of CAM file used to control a photoplotter. It's a standard way of communicating board specifications with manufacturers.

Gold Fingers: These are connectors found on the edge of a PCB after the board has been plated with gold. Hard, smooth, and flat, these fingers are excellent conductors, supporting edge-to-edge connections.

Grid: "Grid" is another term for an electrical grid, an interconnected electrical network that transmits power.

Half-Cut/Castellated Holes: This refers to holes that are drilled on the edge of a board and plated, resulting in a half-circle hole on the edge of the PCB. This is common for PCBs designed for microchip testing.

HDI: An acronym for high-density interconnector, an HDI is a type of PCB fabrication technology. It uses micro blind via technology to manufacture PCBs with high trace density.

*Heterogeneous Packaging: Silicon interposer, silicon chips, stacking silicon chips onto silicon interposer.  

*HI: Heterogeneous Integration.  

Hole Wall Roughness: The irregularities generated on the hole wall by the drilling process are called "hole wall roughness".

IC: Short for an integrated circuit, an IC is also called a microcircuit, microchip, or chip. Essentially, IC describes a method for miniaturizing circuits, especially for semiconductor devices.

Internal Layer: This term refers to the inner layers in multi-layer PCBs. These inner layers are mostly signal layers.
IPC: An abbreviation of Institute of Printed Circuits, a worldwide non-profit association dedicated to the design of PCB wiring. The group helps enterprises achieve greater business success by helping them meet rigorous manufacturing standards, which, in turn, improve overall quality standards.

*JFAC: Joint Federated Assurance Center.  

Kapton Tape: Alternatively called polyimide tape, this electrically insulating tape has numerous useful features, including heat resistance, inextensibility and thinness.

Laminate: This term refers to the combination of different materials through heating, adhesive and welding methods to create a new material with multiple layers. The resulting material has greater strength and stability than the individual materials combined to create the laminate.

Laser Direct Imaging: While the standard imaging techniques require a photo device to transfer images, Laser Direct Imaging has a computerized, highly focused laser beam that directly projects the circuit path onto the PCB. The elimination of a photo device gets rid of alignment and light refraction issues.

Laser Photoplotter: Alternatively called a laser plotter, this type of photoplotter creates a finely lined raster image of the end product. The result is a high-quality, highly accurate plot.

Layer-to-Layer Spacing: This is the distance between PCB layers. The lower the spacing, the more difficult the manufacturing process will be.

Legend: This is a shorthand guide for marking component names and positions. Legends help ease the assembly and maintenance processes.

*LOA: Levels of Assurance.  

LPI: Shorthand for Liquid Photo Imageable, an LPI is a liquid solder mask that is sprayed on a PCB. This method is more accurate, thinner than a dry film solder mask, and more affordable.

Metal Base/Core Printed Board: Metal core PCB refers to a type of PCB with a core material made of metal instead of plastic, resin, or FR4 material.

Mil: A "mil" is another way to say a thousandth of an inch. It's also the equivalent of a "thou. "
mm: "mm" is another way to express a millimeter or a thousandth of a meter.

Motherboard: This is the main board in a computer or an electric device. The motherboard carries key interconnections and components that support the primary functions of the device.

Mounting Hole: This hole is intended to secure the PCB to its final location in a device. To ensure there is no interference, all mounting holes are non-conductive and un-plated.

*MQA: Micro Quantifiable Assurance.  

Multi-Layer PCB: This is a type of PCB with at least three conductive layers of trace and components.

Multimeter: A testing tool used to measure electrical values like current, resistance, and voltage.

Nail Heading: A phenomenon that occurs in the drilling of multilayer PWBs. The normal copper inner layers are drawn out or extruded by the drill which forms a nail head-like shape on the hole wall.

NC Drill: This is a more common name for a Numeric Control drill machine. This type of machine is what assemblers use to drill holes in PCBs.

*NIST: National Institute of Standards and Technology.  

NPTH: Non-Plated Through Holes (NPTH) A non-plated through-hole has no copper plated onto the hole walls; thus, the barrels lack electrical properties. NPTHs were commonly used when PCBs only contained copper tracks printed onto one side. However, their application reduced with the increase of more PCB layers.

*NSTC: National Semiconductor Technology Center.

Open: This is a short way of saying "open circuit, " which is a break in an electrical circuit's continuity. This prevents current from flowing and can disrupt the proper function of a PCB.

*Organic Package: Package made out of organic-based resins. (FR4/Phenolic/Cyanate Ester) 

*OSAT: Outside Assemble and Test. 

*Packaging Fabrication: Making the Interposer.  

*Packaging: Wafer Chip mounted to an Interposer. (Interposer made of Organic Resin) 

Pad: This is one of the most basic composition units of a PCB assembly. A pad is a contact point used to connect components with a via and is the point to which the components are soldered.

Panel: A panel is a combination of boards produced simultaneously to improve efficiency during the manufacturing process. Once the process is finished, these panels are typically broken apart into their singular units before being used.

Panelize: This is the act of grouping multiple PCBs into a panel to improve manufacturing efficiency.

Part Number: This is an identification method used in industry to differentiate parts from one another. It's also used to identify specific parts, which is helpful in identifying problematic assembly batches and preventing incorrect product applications.

Part: This is another word for a component, or a basic piece of electric equipment, such as a resistor, capacitor, potentiometer, valve, radiator, etc.

PCB Base Material: The material upon which the PCB is built. The PCB base material is typically composed of resin, metal, ceramic, or another material with thermal and electric properties that support the PCB's final function.

PCB: An abbreviation of Printed Circuit Board, a PCB is a board that contains a conductive material and components, which act in synchrony to produce a designed response. PCBs rely on electrical circuits, which are either printed or soldered onto the board to elicit the desired result. Printed circuit boards are available in a wide variety of shapes, sizes, and purposes to suit any industry or application.

PCBA: This is an acronym for Printed Circuit Board Assembly, where a company solders components to boards.

Peelable Solder Mask: A solder mask or layer of solder mask that can be peeled from the board.

Photoplotter: A device used in manufacturing to produce artwork onto film by plotting objects instead of images.

Pin: A terminal on a component. It is also called a lead.

Pitch: The distance between pin centers of SMDs.

Plated-Through Hole: Alternatively called a PTH, this is a procedure in which a through-hole is plated so that the hole wall can be conductive. This is often used as a contact point for through-hole components and can be used as a via.

Prepreg: This is the key material for multi-layer PCB manufacturing. it is primarily composed of resin and strengthening material that is then classified into glass-fiber cloth, paper base, compound material, etc.

Press Fit Holes: This is a hole through which a contact terminal can be pressed into a PCB.

Printed Wiring: A process where a design is etched into the conductive metal on a board, producing a wire design for the PCB.

Printing: Part of the PCB manufacturing process where a circuit pattern is printed on the board.

PWB: An acronym for Printed Wiring Board, which is another name for a PCB.

Reflow: This is the process of melting solder to create a joint between a pad and a component or lead.

Resin Smear: Resin Smear is the effect of resin adhering to the inner copper layer in the hole wall.  After the cross-section, the layer is measured (as shown in the figure below) where resin smear is detected. The smear value is the ratio (%) based on the width of the resin smear to the inner layer of copper, that has adhered to the hole wall.

RF: Short for radio frequency, RF is an electromagnetic frequency ranging between 300KHz and 300GHz. RF can also be a type of high-frequency electromagnetic signal.

RoHS: Alternatively known as the Restriction of Hazardous Substances, RoHS is a European environmental protection law. Many global companies must follow RoHS standards to sell products in the EU.

Route/Track: This is the layout of a PCB's wiring structure, which is important for the proper function of the PCB. As a verb, the act of routing means designing such wiring structures.

Schematic: A technical drawing that illustrates the connections between PCB components. Schematics will often include abstract representations of components instead of pictures and is an important first step in PCB design.

*SHIP: State-of-the-art Heterogeneous Integrated Package. 

Short: This is a "short circuit, " which is a connection with low resistance, resulting in excess current at the connecting point. This can cause serious problems in the PCB, including failure.

Silkscreen: This is a layer of epoxy ink applied to a PCB that contains component names and positions. The labels included on silkscreens help to direct workers through the assembly process. Typically, silkscreens are white or yellow, which helps the labels stand out against the PCB's solder mask.

Single-Sided PCB: A PCB design with traces and pads included on only one side of the board.

*SIP: System in Package. 

*SIPH: Silicon Photonics. (Using photons to send info instead of copper traces) Slot: Non-round holes on a PCB that may or may not be plated. These are often required for specific components but are costly due to the labor needed to cut them.

SMT: Short for surface mount technology, this type of assembly technology directly solders SMDs to the surface of a PCB, rather than running components through thru-holes. This allows the board to function without drilling holes through it and also helps improve component density on the surface of the PCB.

*SOC: System on Chip. 

Solder Mask/Solder Resist: This is a layer of material, usually consisting of epoxy resin, which isn't compatible with solder. This material is applied to the entire PCB, except those areas where content needs to be soldered. This process helps to physically and electrically insulate traces, preventing shorts. Solder masks are often green in color, though red and black are also common.

Solder Side: This is the opposite of the component side and is usually regarded as the bottom side.

*SOS: System on Substrate.  

*SOTA: State Of The Art. 

Spacing: This term refers to the distance between wires on a PCB.

*STS (Silicon To Systems) Approach: Building sustainable, regional advanced packaging ecosystems in North America and Europe. It requires the Government, Commercial Industry, and Academia to continue collaborating, developing, and executing. Substrates and Packaging Assembly are critical. Not just Silicon. 

Substrate: This is basically a PCB base material – the main material for printed circuit board fabrication. A substrate can be flexible or rigid and can contain epoxy, metallic, or ceramic properties. The PCB application normally determines the type of substrate to use.

Supported Hole: This is a via with pads on both sides of the PCB. It's also plated inside the via. This means the entire hole can support functions relating to thermal or electrical conductivity.

Surface Finish: Since copper tends to oxidize in natural environments, a surface finish protects the layer from doing so. Oxidation can cause the tin paste to fail or solder incorrectly. The primary types of surface finishes include HASL, ENIG, IMAG, OSP, and others.

Tented Via: This is a type of via that has a dry film solder mask covering both its pad and its plated-thru hole. This solder mask insulates the via completely, protecting the PCB against shorts. Some vias are tented only on one side to allow for testing on the other.

Thou: This is shorthand for a thousandth of an inch. It's another way to say "mil. "

Through-Hole/Thru-Hole: This refers to a hole passing through at least two layers of a multi-layer PCB. It's also used as a descriptor for components with parts or pins that run through a board to be soldered to another side.

Trace/Track: This refers to the copper path printed on a PCB. It functions similarly to an electrical wire, connecting components on a PCB board. The word "trace" is also used to refer to a segment of the path.

Trace: This term refers to the width of a PCB's wires.

*TSV: Through Silicon Via. 

UL: UL stands for Underwriter's Laboratories, Inc., a renowned company specializing in establishing safety standards and independently assessing products according to these standards.

Unsupported Hole: This type of hole has a pad on the solder side, but no pad on the component side. There is also no metal layer inside the hole. This means the hole has no conductive reinforcement.

*Valley of Death: Concepts die between invention and Commercialization.  

Vector Photoplotter: Alternatively called a vector plotter or Gerber Photoplotter, this type of photoplotter draws a plot line by line using light manipulation technology. This method can produce larger plots, but it is also much slower than the more modern laser photoplotter method.

Via Filled with Resin/Via Plugged: This is a via that is filled with epoxy resin. Once filled, copper can be soldered to the surface of the resin without influencing the final product.

Via in Pad: Also called a thru-hole on the pad, a via in pad functions as an electric connection between layers. It is useful for multi-layer components or for fixing the positions of components.

Via: This term refers to plated through-holes that connect signals between traces on different layers of a PCB. These holes have conductive copper interiors to maintain an electrical connection.

V-Scoring: This is an incomplete cut through a panel, which is often used to help break apart panels of PCBs into single units.

Wicking: Plating that migrates along the glass fiber insulation layer.