2023’s Most Complete PCB Terminology Guide: The Essential Knowledge You’ve Been Missing Out On

Introduction

Have you ever looked at a printed circuit board (PCB) and wondered about the intricate network of lines, holes, and components? What do all these terms like ‘via’, ‘trace’, ‘solder mask’ mean? How do they contribute to the complex symphony that is a functioning electronic device? Understanding the terminology used in PCB design and manufacturing can seem like learning a new language. But don’t worry, we’ve got you covered.

In this comprehensive guide, we will delve into the world of PCB terminology. We’ll explore everything from basic design terms to advanced manufacturing jargon. Whether you’re a hobbyist just starting out or a seasoned engineer looking for a refresher, this article will serve as your go-to resource for all things PCB.

So, buckle up and prepare for a deep dive into the fascinating world of PCB terminology. You’re about to become fluent in the language of electronics!

PCB Design Terminology

Basic Design Terms

• Schematic: A schematic is a diagram that represents the elements of a system using abstract, graphic symbols rather than realistic pictures. It serves as a blueprint of the circuit, showing how components are connected together, but not necessarily how they will be physically laid out on the PCB.
• Layout: The layout of a PCB refers to the arrangement of components and the routing of the electrical connections between them on the physical board. It is a crucial step in PCB design as it directly impacts the performance and functionality of the final product.
• Footprint: In PCB design, a footprint is the arrangement and dimensions of pads used to mount a component on the board. It’s a crucial aspect of component selection and placement, as the footprint must match the physical dimensions and pin configuration of the component. Incorrect footprints can lead to assembly issues and circuit malfunctions.
• Via: In PCB design, a via is a small hole that’s drilled into the board, allowing for electrical connection between different layers of the PCB. Vias play a crucial role in multi-layer PCBs, enabling complex routing and connectivity.
• Trace: A trace is a continuous path of copper on a PCB that electrically connects different components. The width and length of traces can significantly impact the performance of the circuit, affecting signal integrity, power delivery, and thermal management.
• Pad: A pad is a small area of copper on a PCB where a component pin makes an electrical connection.
• Silk Screen: The silk screen on a PCB contains human-readable text and symbols that provide information about the board and its components.

Advanced Design Terms

• Ground Plane: A ground plane is a large area of copper on a PCB that is connected to the power supply’s ground.
• Power Plane: Similar to a ground plane, a power plane is a large area of copper on a PCB that is connected to the power supply voltage.
• Signal Integrity: Signal integrity refers to the quality of an electrical signal.
• Electromagnetic Compatibility (EMC): EMC is the ability of an electronic system to function correctly in its electromagnetic environment without introducing intolerable electromagnetic disturbance to anything in that environment.
• Electromagnetic Interference (EMI): EMI is a disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source.
• Controlled Impedance: Controlled impedance is the characteristic impedance of a transmission line formed by PCB traces.
• High-Speed Design: High-speed design refers to the design of circuits where signal integrity effects must be considered due to the high signal frequencies or fast switching times involved.
• Annular Ring: The annular ring is the area of copper pad around a drilled and finished hole on a PCB.
• Blind Via: A blind via is a via that connects an outer layer to one or more inner layers but does not go through the entire board.
• Buried Via: A buried via is a via that connects two or more inner layers and does not have connections to the outer layers.
• Copper Weight: Copper weight refers to the thickness of the copper layer on the PCB.
• Crosstalk: Crosstalk is a form of interference caused by the electric or magnetic fields of one signal affecting a nearby signal.
• Keepout Area: A keepout area is a defined area on the PCB where components and traces are not placed.
• Netlist: A netlist is a list of all the electrical connections in a circuit.
• Thermal Relief: Thermal relief is a pattern used to connect a pad to a copper pour in a way that restricts the flow of heat.
• Tombstoning: Tombstoning is a defect in surface mount assembly where a component stands up vertically.
• Twist and Bow: Twist and bow refers to the deformation of a PCB, where it is not perfectly flat.
• Z-Axis Expansion: Z-axis expansion is the change in thickness of a PCB due to temperature changes.

Design Software Terms

• EDA (Electronic Design Automation): EDA is a category of software tools for designing electronic systems such as printed circuit boards and integrated circuits.
• DRC (Design Rule Check): DRC is a process in which a software tool checks a PCB layout to ensure it meets the design rules for minimum trace width, minimum spacing between traces, etc.
• CAD (Computer-Aided Design): CAD is the use of computers to aid in the creation, modification, analysis, or optimization of a design.
• DFM (Design for Manufacturability): DFM is a design methodology that focuses on simplifying the manufacturing process to reduce production costs and increase product quality.
• ERC (Electrical Rule Check): ERC is a process in which a software tool checks a schematic for errors such as unconnected pins or incorrect power connections.
• Gerber Files: Gerber files are a standard file format used in the fabrication of PCBs. They contain information about the copper layers, solder mask, silkscreen, and drill holes.
• BOM (Bill of Materials): A BOM is a list of all the components used in a PCB design. It typically includes information such as the component designators, part numbers, quantities, and descriptions.

Design for Manufacturing (DFM) Terms

• Solder Mask: Solder mask is a protective layer applied to the bare board to prevent solder bridging between closely spaced pads and to protect the copper from corrosion.
• Solder Paste: Solder paste is a mixture of tiny solder particles and flux that is used in the assembly process to solder surface-mount components to the PCB.
• Pick and Place File: A pick and place file is used by the assembly machine to determine the correct position and orientation for each component on the board.
• Panelization: Panelization is a technique used in PCB manufacturing where multiple boards are fabricated as a single unit to improve manufacturing efficiency.
• Test Points: Test points are specific locations on a PCB that are easily accessible for testing purposes. They are usually marked on the silk screen and connected to important signals or power rails.

PCB Components Terminology

Basic Components

• Resistor (R): A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. It is used to limit current, divide voltage, and in some cases, generate heat.
• Capacitor (C): A capacitor is a passive two-terminal electronic component that stores electrical energy in an electric field. It can be used for a variety of purposes, such as smoothing, filtering, and energy storage.
• Inductor (L): An inductor, also called a coil or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it.
• Diode (D): A diode is a two-terminal electronic component that conducts current primarily in one direction.
• Transistor (Q): A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power.

Advanced Components

• Integrated Circuit (IC): An integrated circuit or monolithic integrated circuit is a set of electronic circuits on one small flat piece of semiconductor material, usually silicon.
• Microcontroller (U): A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals.
• Operational Amplifier (Op-Amp, U): An operational amplifier is a high-gain voltage amplifier with a differential input and, usually, a single-ended output.
• Digital to Analog Converter (DAC, U): A DAC is a system that converts a digital signal into an analog signal.
• Analog to Digital Converter (ADC, U): An ADC is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal.
• Crystal Oscillator (Y): A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency.
• Light Emitting Diode (LED, D): A LED is a semiconductor light source that emits light when current flows through it.
• Fuse (F): A fuse is a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level.
• Switch (S): A switch is a component that can “make” or “break” an electrical circuit, interrupting the current or diverting it from one conductor to another.
• Connector (J): A connector is a device that allows the coupling of an electrical conductor to a port so that electrical signals can flow from the conductor to the device.
• Relay (K): A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals.
• Potentiometer (P): A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.

Additional Components

• Battery (BT): A battery is a device consisting of one or more electrochemical cells with external connections for powering electrical devices.
• Speaker (SP): A speaker is an electroacoustic transducer which converts an electrical audio signal into a corresponding sound.
• Microphone (M): A microphone is a device that captures audio by converting sound waves into an electrical signal.
• Motor (M): A motor is a machine that converts electrical energy into mechanical energy.
• Display (DS): A display is an output device for presentation of information in visual or tactile form.
• Thermistor (TH): A thermistor is a type of resistor whose resistance is dependent on temperature.
• Photodiode (PD):

A photodiode is a semiconductor device that converts light into an electrical current.

• Phototransistor (Q): A phototransistor is a semiconductor device that is used to detect light and convert it into an electrical signal.
• Voltage Regulator (VR): A voltage regulator is a system designed to automatically maintain a constant voltage level.
• RF Module (RF): An RF module is a small electronic device used to transmit and/or receive radio signals between two devices.
• Memory Chip (U): A memory chip is an electronic data storage medium that uses integrated circuit technology to store information.
• Clock Generator (CLK): A clock generator is a circuit that produces a timing signal for use in synchronizing a circuit’s operation.

PCB Layout Terminology

Basic Layout Terms

• Board Outline: The board outline defines the physical size and shape of the PCB. It is the first thing that is defined when starting a new layout, and it determines the space available for component placement and routing.
• Component Placement: Component placement refers to the positioning of components on the PCB layout. Proper component placement can have a significant impact on the performance of the final product, as it affects signal integrity, power distribution, thermal management, and manufacturability.
• Copper Pour: Copper pour refers to the practice of filling unused space on a PCB with copper that is connected to a power supply layer, usually ground. This technique is often used to reduce electromagnetic interference by providing a shield against external noise sources. Additionally, copper pour can help improve heat dissipation, as copper is an excellent conductor of heat. This can be particularly beneficial in high-power designs where managing heat is a critical concern.
• Clearance: Clearance refers to the minimum distance required between different electrical objects on the PCB to prevent electrical shorting and interference.

Advanced Layout Terms

• BGA (Ball Grid Array): BGA is a type of surface-mount packaging used for integrated circuits. It provides more interconnection pins than can be put on a dual in-line or flat package.
• QFN (Quad Flat No-leads): QFN is a flat, square or rectangular surface-mount plastic package with a large number of leads on all four sides.
• Differential Pair: A differential pair is a pair of traces that carry a differential signal. They are routed closely together to maintain the same impedance and signal quality.
• Via Stitching: Via stitching is the practice of using multiple vias to connect two planes together. This technique can help to reduce noise and improve thermal performance.
• Length Matching: Length matching is a technique used in high-speed designs to ensure that critical signals arrive at their destination at the same time.
• Decoupling Capacitors: Decoupling capacitors are used in electronic circuits to prevent undesired coupling of one part of a circuit to another.
• Signal Plane: Signal planes are layers of a multi-layer PCB that are dedicated to carrying signal traces.

PCB Manufacturing Terminology

Basic Manufacturing Terms

• Substrate: The substrate, often made of FR4, is the insulating material that provides the mechanical rigidity of the PCB. It serves as the base upon which all other layers (copper, solder mask, silkscreen) are added.
• Copper Clad: Copper clad refers to the substrate that has been coated with a thin layer of copper, which is then etched away to form the traces and pads. The copper provides the conductive pathways for the circuit.
• Etching: Etching is the process of using chemicals to remove unwanted copper from the PCB, leaving only the desired traces and pads.
• Drilling: Drilling is the process of creating holes in the PCB for component leads or vias.
• Plating: Plating is the process of adding a layer of copper to the drilled holes to create electrical connections between layers.

Advanced Manufacturing Terms

• Surface Finish: The surface finish is applied to the exposed copper pads to prevent oxidation and to provide a solderable surface for component assembly.
• Solder Mask: In the manufacturing process, a solder mask is a protective layer applied to the bare board. Its primary function is to prevent solder bridging between closely spaced pads during the soldering process, which can lead to short circuits. It also protects the copper from oxidation and environmental damage..
• Silkscreen: In PCB manufacturing, silkscreen is used to print reference indicators, such as component designators, switch settings, test points and other indications helpful in assembling, testing and servicing the circuit board.
• Lamination: Lamination is the process of bonding together multiple layers of material using heat and pressure.
• Multilayer PCB: A multilayer PCB is a PCB that has more than two layers of copper traces.
• Panelization: Panelization is a technique used in PCB manufacturing where multiple boards are fabricated as a single unit to improve manufacturing efficiency.
• PTH (Plated Through Hole): PTH is a hole in a PCB that has been plated with copper to create an electrical connection between different layers of the board.
• NPTH (Non-Plated Through Hole): NPTH is a hole in a PCB that is not plated with copper. These holes are typically used for mounting or mechanical alignment.
• HASL (Hot Air Solder Leveling): HASL is a type of surface finish that involves coating the PCB with molten solder and then using hot air to level and smooth the solder.
• ENIG (Electroless Nickel Immersion Gold): ENIG is a type of surface finish that involves depositing a thin layer of nickel on the PCB, followed by a thin layer of gold.
• OSP (Organic Solderability Preservatives): OSP is a type of surface finish that involves applying a thin layer of organic material over the exposed copper to prevent oxidation.
• FCT (Functional Test): FCT is a type of PCB testing that verifies the correct functioning of the PCB.
• FPT (Flying Probe Test): FPT is a type of PCB testing that uses moving probes to test the electrical performance of the PCB.
• AXI (Automated X-ray Inspection): AXI is a technology used to inspect the hidden features of target objects or products with X-rays.
• ICT (In-Circuit Test): ICT is a type of test that checks the functionality of the PCB by applying signals to the board and measuring its response.
• AOI (Automated Optical Inspection): AOI is a visual inspection process that uses a camera to scan the PCB for manufacturing defects.

PCB Materials Terminology

Substrate Materials

• FR4 (Flame Retardant 4): FR4 is the standard substrate material used in PCBs. It is a type of glass-reinforced epoxy laminate material, known for its low cost, good electrical properties, and excellent mechanical strength.
• CEM (Composite Epoxy Material): CEM is a type of PCB material that is commonly used due to its low cost. CEM1 and CEM3 are the most common types.
• High-Frequency Materials: High-frequency materials are specialized PCB substrates designed to perform well at high frequencies and in high-speed designs. They offer lower signal loss and better performance in RF/microwave environments compared to standard materials like FR4.
• Flexible Materials (FPC, Flexible Printed Circuits): Flexible materials, such as polyimide, are used to manufacture flexible PCBs that can bend without breaking.
• Aluminum (MCPCB, Metal Core PCB): Aluminum is often used as a substrate for high power LED lights or power electronics, where heat dissipation is a significant concern.

Conductive Materials

• Copper: Copper is the primary material used for creating traces, pads, and planes on a PCB due to its excellent electrical conductivity.
• Conductive Ink: Conductive ink is a type of ink that can conduct electricity and is used in a variety of applications, including PCBs.
• Lead-Free Solder: Lead-free solder is a type of solder that does not contain lead, making it more environmentally friendly than traditional solder.

Protective and Insulating Materials

• Solder Mask: As a material, the solder mask is a layer of insulating polymer usually applied to the outer layers of the PCB. It provides insulation, protects the board’s components and traces, and prevents tin from spreading and shorting during soldering.
• Silkscreen: Silkscreen, in terms of materials, refers to the layer of ink traces used to identify components, test points, parts of the board, warning symbols, logos and marks relevant to the board.
• Thermal Interface Materials (TIMs): TIMs are materials used to enhance heat transfer from electronic components to heat sinks.

Specialized Materials

• Prepreg: Prepreg is a type of material used in the manufacture of multilayer PCBs. It is a fiberglass impregnated with resin that is partially cured.
• Core: In the context of multilayer PCBs, a core is a layer of rigid material, usually FR4, that is fully cured and laminated with copper.
• Rogers Material: Rogers material is a type of high-frequency material known for its low dielectric loss, making it suitable for high-speed designs.
• PTFE (Polytetrafluoroethylene): PTFE is a high-frequency material known for its low dielectric constant and low signal loss.

Conclusion

In conclusion, understanding PCB terminology is crucial for anyone involved in electronics, whether you’re a hobbyist, a professional engineer, or even an enthusiast. With this comprehensive guide, we hope to have shed light on the most important terms and concepts in the field. From design to manufacturing, each term carries its weight and contributes to the intricate dance that is a functioning PCB.

FAQs

1. What is the difference between a via and a trace in PCB design? A via is a small hole that’s drilled into the board, allowing for electrical connection between different layers of the PCB. A trace, on the other hand, is a continuous path of copper on a PCB that electrically connects different components.
2. What is the role of solder mask in PCB manufacturing? Solder mask is a protective layer applied to the bare board to prevent solder bridging between closely spaced pads and to protect the copper from corrosion.
3. What does ‘panelization’ mean in the context of PCB manufacturing? Panelization is a technique used in PCB manufacturing where multiple boards are fabricated as a single unit to improve manufacturing efficiency.
4. What is the significance of ‘copper weight’ in PCB design? Copper weight refers to the thickness of the copper layer on the PCB. It’s an important factor in determining the current-carrying capacity and thermal characteristics of the board.
5. What is a ‘netlist’ in PCB design? A netlist is a list of all the electrical connections in a circuit. It’s a crucial part of the design process, ensuring that all components are correctly connected.