Printed circuit boards (PCBs) provide the fundamental interconnect platform for electronic devices and systems. By electrically and physically connecting components in a structured layout, PCBs enable complex functionality within sophisticated products ranging from computers to cars. The specific components integrated into a PCB determine its capabilities.

There are a diverse array of circuit board components that can be incorporated depending on the application. Here is an overview of the major types of components found in modern PCB designs.

Integrated Circuits

Integrated circuits (ICs) are complex microchips that integrate large numbers of electronic circuits and components into a very small footprint. They perform computational data processing and enable programmable functions. Common types of ICs include:

• Microprocessors – Central processing unit chips that execute program instructions and logic operations. Microprocessors enable devices to process data.
• Microcontrollers – Single chip systems that contain memory, processors, inputs/outputs, and other features to control embedded devices.
• Graphics Processing Units (GPUs) – Specialized processors optimized for rendering complex visual graphics. Essential for video games, CAD, and simulations.
• Digital Signal Processors (DSPs) – Optimized for real-time processing of analog/digital signals like audio, video, and radio frequencies. Enable functions like voice recognition.
• Field Programmable Gate Arrays (FPGAs) – Reconfigurable chips whose functions can be customized by engineers after manufacturing. Used to prototype circuits.
• Application Specific ICs (ASICs) – Custom ICs designed for a particular use vs. general purpose. Provide maximum optimization but less flexibility.

IC package types range from plastic dual in-line packages (DIPs) to compact ball grid arrays (BGAs). ICs enable endless functions from data analytics to image processing.

Discrete Semiconductors

Discrete semiconductors are single function circuit elements rather than complex integrated chips. This includes:

• Transistors – Amplify or switch electronic signals and power. Types include bipolar junction (BJT), field effect (FET), and metal-oxide-semiconductor (MOS).
• Diodes – Allow current to flow in only one direction. Common forms are rectifier, Zener, and light emitting diodes.
• Thyristors – Act as electronic switches or rectifiers. Used for power control applications.
• Integrated Passive Devices – Combine multiple passive components like resistors and capacitors into a single IC. Save board space.

Discrete semiconductors provide dedicated functions to supplement the capabilities of ICs on PCBs.

Passive Components

Passive components do not require a power source to operate. They make up a significant portion of the parts on a PCB. Major types of passive components include:

• Resistors – Limit electric current flow and create voltage drops in circuits. Available in many form factors and resistance values.
• Capacitors – Store electric charge to filter signals, block DC, stabilize power supplies, and resonate with inductors. Popular types are ceramic, electrolytic, and film.
• Inductors – Coils of wire that induce magnetic fields and react to changes in current. Used in filters, oscillators, and transformers.
• Networks – Combinations of capacitors, inductors, and/or resistors grouped together as a single passive network.
• Connectors – Allow detachable connection between a PCB and wires or cables interfacing with other systems. Common connectors are card edge, D-subminiature, RJ11/45, and USB.
• Crystals/Oscillators – Generate precise frequencies as a system time base or clock signal for microcontrollers.

Passive components enable essential functions on PCBs despite their simplicity.

Electromechanical Components

Electromechanical components interface electrical systems with mechanical actions. This category includes:

• Switches – Open or close circuits electronically or mechanically. e.g. pushbutton, toggle, DIP switches.
• Relays – Electrically operated switches for controlling high power circuits. Allow isolation between control and operated circuits.
• Filters – Block specific frequencies while allowing others to pass. Reduce noise and interference.
• Connectors – Enable quick installation and removal of wires/cables interfacing with external equipment. Common types are circular, D-sub, RCA, and USB.
• Heat Sinks – Dissipate heat generated by high-power components. Prevent thermal overload.
• Fans – Provide forced air cooling across PCB components to maintain safe operating temperatures.

Electromechanical parts act as critical bridges between PCBs and the physical world in many designs.

User Interface Components

For products that interact with users, PCBs integrate various interface components:

• Buttons/Keypads – Register user input like power on/off, selections, and data entry.
• Touch Sensors – Detect input through sensitive surfaces that register finger touches and movements.
• Microphones – Convert acoustic sounds to analog electrical signals. Enable voice commands and recordings.
• Speakers – Actuate to produce audible sound from electrical signals driven by circuits.
• Buzzers – Provide simple tones and alerts to users based on programmed conditions.
• LEDs – Illuminate to provide visible indicators and feedback to users about device status.
• LCD/OLED Displays – Display visual information like text, graphics, and images via pixel arrays.

User interfaces enable intuitive interaction with electronic products and systems.

Radio Frequency (RF) Components

For wireless transmitting and receiving:

• Antennas – Propagate and receive radio waves in tuned frequency bands. Come in forms like PCB traces, chip, and external whip/dish.
• Modulators – Interface baseband signals with a carrier frequency signal. Support wireless transmission.
• Demodulators – Extract original data signal from modulated high frequency wireless signal. Enable wireless reception.
• Amplifiers – Boost the power of RF signals for stronger transmission over distance. Also amplify received signals.
• Mixers – Frequency conversion of signals up or down by combining with local oscillator. Assist transceiver tuning.
• Duplexers – Allow simultaneous transmission and reception sharing an antenna. Key for full-duplex wireless like phones.
• Filters – Frequency selective networks to isolate and filter wireless signals within allocated bands.

RF parts transmit, receive, and process high frequency signals essential for wireless systems.

Power Supply Components

PCBs require power conversion and distribution components:

• Voltage Regulators – Provide stable, steady voltage levels from input supply to sensitive ICs and circuits. Types are linear, switching, and low dropout (LDO).
• Power Transformers – Transfer electrical power between circuits isolated through electromagnetic induction. Change voltage and current levels.
• Rectifiers – Convert alternating current (AC) into the direct current (DC) needed by electronics. Usually diodes or diode bridges.
• Inverters – Invert DC into AC waveforms. Allow off-grid AC power generation from DC sources like batteries.
• Power Controllers – Manage and optimize power distribution and charging. Often used in battery-powered devices.
• Backup Batteries – Maintain power to PCB components like real-time clocks and memory when main power is interrupted. Common examples are coin cell and supercapacitors.

Efficient power supply is vital for stable, reliable PCB operation.

Specialized Components

Certain applications utilize more unique components like:

• Sensors – Measure physical properties like acceleration, orientation, pressure, temperature, gas levels, proximity, etc. and produce signals processors can analyze.
• Actuators – Convert electrical signals into physical actions. Examples are motors, pumps, linear actuators, and more. Enable electronic control of devices.
• Camera modules – Contain image sensor, lens, and processing ICs to capture digital photographs and video.
• GPS modules – Receive and process satellite signals to determine real-time global position for navigation applications.

Specialized components tailored for particular functions are available for diverse PCB applications.

PCB Materials

Besides solder and coatings, PCB substrate materials provide the foundation:

• FR-4 – Woven fiberglass reinforced epoxy. The most common rigid PCB material. Offers good strength and dielectrics.
• CEM-1, CEM-3 – Cotton paper and woven fiberglass substrates. Have high thermal resistance for demanding environments.
• PTFE – Polytetrafluoroethylene fluoropolymer resin with low dielectric loss. Ideal for high frequency applications.
• Polyimide – Flexible material suitable for dynamically flexing PCBs in wearables and other movable products.
• Aluminum – Metal-core PCBs for maximum heat dissipation, ideal for high-power LEDs and power electronics.

Ceramics – Alumina, aluminum nitride, and other technical ceramics have excellent thermal conductivity plus electrical insulation.

PCB substrate and base materials provide the platform essential structures are built upon.

Common PCB Features

Most PCBs share common design elements:

• Traces – Etched copper pathways that form circuits and interconnects between components.
• Planes – Continuous copper layers that serve as voltage reference and decoupling for signals.
• Solder Mask – Epoxy layer over traces that prevents solder bridging between metal features.
• Silkscreen – Printed layer that identifies components, text, logos, and other markings.
• Vias – Plated through holes that connect traces between layers in multilayer PCBs.

These standardized PCB design structures enable robust circuit integration and performance.

Component Integration

With hundreds or thousands of components populating modern printed circuit boards, PCB design is a highly complex integration task that requires electrical and mechanical engineering expertise. Component selection, placement, routing, thermal analysis, and signal integrity optimizations are all crucial to achieving fully functional PCB systems that maximize reliability, efficiency, and manufacturability.

The components described here represent the fundamental building blocks designers combine in innovative ways to create electronic products that transform how we live, work, and play.

FQA

What are the most common integrated circuits used in PCBs?

Some widely used integrated circuits are microprocessors and microcontrollers for data processing, memory and data storage chips, power management ICs, analog-to-digital converters, and display driver ICs.

What are some examples of electromechanical components found on PCBs?

Typical electromechanical parts on PCBs include switches, relays, connectors, filters, fans, heat sinks, and buzzers or speakers for audio signals.

Why are passive components like resistors and capacitors essential in circuit boards?

Passive components enable functions like managing voltage and current levels, filtering signals, blocking DC, storing electrical charges, terminating traces, and helping match impedances.

What are some specialized components used in specific types of PCBs?

Specialized parts can include sensors, GPS modules, accelerometers, gyroscopes, antennas, oscillators, photodiodes, thermocouples, solenoids, and backup batteries or supercapacitors.

What are the most important materials making up the structure of printed circuit boards?

Major PCB substrate materials are FR-4 fiberglass/epoxy composite, CEM substrates, polyimide, PTFE, ceramic-filled substrates, and aluminum or copper for metal core boards.