Commonly Used Electronic Components for PCBA

Introduction

 

Printed Circuit Board Assembly (PCBA) is the process of soldering and assembling electronic components onto a printed circuit board (PCB) to create a functional electronic device. The success of a PCBA depends on selecting the right components, as they determine the performance, efficiency, and reliability of the final product. Each component plays a vital role in ensuring smooth circuit operation, and understanding their characteristics, applications, and limitations is crucial for designing high-quality electronic products. This blog explores the most commonly used electronic components in PCBA, detailing their functions, types, key considerations, and real-world applications. 

 

The manufacturing process of PCBA mainly includes components mounting, welding, post-welding processing and functional testing. The first is the component mounting, which is a process of welding the patch components, plug-in components, etc., to the PCB. Then there is welding, through traditional wave soldering or modern lead-free welding and other methods, the components are firmly fixed on the PCB. After that, the welding process is mainly to remove the welding slag on the PCBA surface, clean the PCBA surface, and check the solder joints and components of PCBA. Finally, the functional test is carried out, which is the last step in the PCBA process, and the PCBA is fully functional tested by various test equipment to ensure the stability and reliability of PCBA.

 

PCBA products are widely used in various electronic products, such as household appliances, communication equipment, automotive electronics, industrial control equipment, etc.  You can see it everywhere.

 

Different electronic products have different requirements for PCBA. Some require PCBA to be small and exquisite, some require PCBA to be high temperature and high pressure resistant, and some require PCBA to be waterproof and dustproof. With the rapid development of 5G, artificial intelligence, Internet of Things and other fields, PCBA will be more widely used, and PCBA’s performance and reliability requirements will also be higher.

 

 

Classification of Circuit Board Components

 

 

Circuit board components are classified based on the functionality, construction and the characteristics. There are mainly 3 types of circuit board components:

 

• Passive Components

Components that do not require any external power source to operate are called passive components. These components are used in controlling, filtering the signals and to store energy. Few examples of passive components are resistor, capacitor, inductors and so on.

 

• Active Components

Components that require external sources to operate are called active components. These circuit board components rely completely on the external source to perform the functionalities. Few examples of active components are transistors, op-amps and diodes.

 

• Integrated Circuits

Integrated circuits are semiconductor devices that have multiple active and passive components integrated onto a single chip. It has a wide range of functions which includes memory storage, processing the signal, performing logical operations and many more. They are different types of IC’s such as analog, digital and mixed-signal.

 

 

Fundamental PCB Components & Their Functions

 

 

Every printed circuit board (PCB) is built using a mix of passive, active, and electromechanical components. These tiny parts work together to ensure smooth electrical flow, regulate power, and allow devices to perform their intended functions. Let’s break down the key components and their roles in a PCB.

 

 

Passive Components

 

Passive components are the supporting players in a circuit—they don’t require an external power source to function but are essential for controlling current, storing energy, and filtering signals.

 

1. Resistors: Controlling Current & Voltage

 

A resistor is one of the most common components on a PCB. Its main job is to control the flow of current by providing resistance, measured in ohms (Ω). Resistors are color-coded to indicate their resistance values, making them easy to identify on a PCB. Key Functions of Resistors:

 

• Current Limiting – Prevents excessive current from damaging other components.

• Voltage Division – Helps divide voltage across different circuit sections.

• Signal Conditioning – Adjusts and shapes electrical signals to ensure stable operation.

 

 

2. Capacitors: Storing & Releasing Electrical Energy

 

A capacitor stores electrical energy and releases it when needed. Think of it like a tiny battery that quickly charges and discharges. Different types of capacitors (ceramic, electrolytic, film) serve specific purposes depending on the circuit design. Capacitors are critical for smoothing power fluctuations and filtering noise in circuits. Common Uses of Capacitors:

 

• Energy Storage – Supplies quick bursts of energy.

• Filtering – Removes unwanted noise from power and signal lines.

• Coupling & Decoupling – Blocks DC signals while allowing AC signals to pass.

• Timing Applications – Used in oscillators and timers.

 

3. Inductors: Managing Magnetic Energy & Noise Suppression

 

An inductor is a coil of wire that stores energy in a magnetic field when current flows through it. Inductors are especially useful in high-frequency circuits where filtering and signal conditioning are needed. Inductors are commonly used in power supplies, filters, and radio-frequency circuits. Inductor Applications:

 

• Energy Storage – Helps manage power flow in switching circuits.

• Noise Suppression – Reduces interference in electronic signals.

• Filtering – Works with capacitors to smooth out voltage fluctuations.

 

4. Transformers: Converting & Isolating Voltage

 

A transformer is a passive component that transfers electrical energy from one circuit to another through magnetic induction. Transformers convert voltage levels, ensuring that devices receive the correct amount of power. Transformers are widely used in power supplies, audio circuits, and communication systems. Why Transformers Matter:

 

• Voltage Conversion – Steps up or steps down voltage levels.

• Isolation – Keeps different sections of a circuit electrically separated for safety.

• Impedance Matching – Helps transfer maximum power between circuits.

 

5. Fuses & Varistors: Protecting Against Overcurrent & Surges

 

A fuse is a safety component that prevents excessive current from damaging a PCB. If too much current flows through, the fuse blows (breaks the circuit), preventing further damage. A varistor (voltage-dependent resistor) protects circuits from voltage spikes by absorbing excessive energy. Protection Features:

 

• Fuses – Protect against short circuits and current surges.

• Varistors – Guard against voltage spikes from external sources like lightning.

 

These components are critical for extending the lifespan of electronic devices and preventing costly failures.

 

Component	Function	Key Applications
Resistors	Control current flow and voltage division	Current limiting, voltage division, signal conditioning
Capacitors	Store and release electrical energy	Energy storage, filtering, coupling/decoupling, timing applications
Inductors	Store energy in a magnetic field, filter noise	Power supplies, noise suppression, signal filtering
Transformers	Convert and isolate voltage	Voltage conversion, circuit isolation, impedance matching
Fuses	Protect circuits by breaking during overcurrent	Short circuit protection, overcurrent safety
Varistors	Absorb voltage spikes to protect circuits	Surge protection from lightning, electrical noise reduction

 

Active Components

 

Unlike passive components, active components require an external power source to function. These parts control signals, amplify power, and regulate voltage in electronic circuits.

 

1. Diodes: Controlling Current Flow

 

A diode is a one-way street for electricity. It allows current to flow in one direction while blocking it in the opposite direction. Special types of diodes, like Zener diodes and Schottky diodes, serve unique functions in power regulation and high-speed applications. Common Uses of Diodes:

 

• Rectification – Converts AC to DC in power supplies.

• Voltage Regulation – Maintains a stable voltage level.

• Signal Processing – Used in radio frequency and communication circuits.

 

2. Transistors (BJTs & FETs): Amplifying & Switching Signals

 

Transistors are the building blocks of modern electronics. They act as amplifiers and switches, controlling the flow of electrical signals. Without transistors, we wouldn’t have microprocessors, memory chips, or modern computing devices. Types of Transistors:

 

• Bipolar Junction Transistor (BJT) – Commonly used for amplification.

• Field Effect Transistor (FET) – Used in high-speed and low-power applications.

 

3. Integrated Circuits (ICs): The Brain of Electronics

 

An integrated circuit (IC) is a compact electronic chip that contains multiple components like transistors, resistors, and capacitors. ICs are used in everything from microcontrollers to processors. ICs come in different types, including analog ICs, digital ICs, and microcontrollers. Why ICs Are Essential:

 

• Space-Saving – Combines multiple functions into a single chip.

• High Performance – Enables complex computations and processing.

• Power Efficiency – Reduces overall power consumption.

 

4. Microprocessors & Op-Amps: Processing & Signal Control

 

A microprocessor is the brain of a computer, handling data processing and control functions. An operational amplifier (Op-Amp) is used in signal processing, filtering, and voltage amplification. Where You’ll Find Them:

 

• Microprocessors – In computers, smartphones, and embedded systems.

• Op-Amps – In audio circuits, sensors, and analog computing.

 

5. Voltage Regulators: Ensuring Stable Power Supply

 

A voltage regulator maintains a constant voltage level to prevent fluctuations that could damage sensitive components. Why They Matter:

 

• Prevents Overvoltage Damage – Keeps circuits safe.

• Ensures Stable Operation – Critical for microcontrollers and ICs.

• Used in Power Supplies – Regulates voltage in chargers and adapters.

 

 

Component	Function	Key Applications
Diodes	Control current flow in one direction	AC to DC conversion, voltage regulation, signal processing
Transistors (BJTs & FETs)	Amplify and switch electrical signals	Amplifiers, switching circuits, microprocessors
Integrated Circuits (ICs)	Perform complex electronic functions	Microcontrollers, digital processors, analog circuits
Microprocessors & Op-Amps	Process data and amplify signals	Computing, signal filtering, control systems
Voltage Regulators	Maintain a stable voltage level	Power supplies, preventing voltage fluctuations

 

Electromechanical Components

 

Electromechanical components involve both electrical and mechanical movement to control circuits.

 

1. Switches & Relays: Turning Circuits On & Off

 

A switch allows users to manually turn a circuit on or off, while a relay uses an electrical signal to switch circuits remotely. Key Functions:

 

• Switches – Control power flow in devices.

• Relays – Used in automation, industrial control, and automotive applications.

 

2. Connectors: Linking Components Together

 

A connector allows electrical signals to pass between different PCBs, components, or external devices. Where Connectors Are Used:

 

• Computers & Smartphones – USB, HDMI, and audio ports.

• Automotive & Industrial Electronics – Secure cable connections.

 

Component	Function	Key Applications
Switches	Manually turn circuits on or off	Power control in devices, user interfaces
Relays	Electrically controlled switches for remote circuit switching	Automation, industrial control, automotive applications
Connectors	Establish electrical connections between PCBs and external devices	USB, HDMI, audio ports, industrial and automotive wiring

 

How to Place PCB Components for Optimal Performance

 

Designing a printed circuit board (PCB) isn’t just about choosing the right components—it’s also about where and how you place them. Poor placement can lead to signal interference, overheating, and manufacturing issues, while an optimized layout ensures reliable performance, easier assembly, and efficient power management. Here’s how to place PCB components strategically to maximize performance.

 

 

 

Mechanical Constraints: 

 

Before placing components, consider the physical limitations of the PCB. The board must fit within the enclosure or device it’s designed for, so its size, shape, and mounting points need to be carefully planned.

 

Key Mechanical Considerations:

 

• Board Size & Shape – Ensure the PCB fits within the device while leaving enough space for traces and components.

• Mounting Holes – Place holes in strategic positions to securely attach the PCB inside the device.

• Edge Connectors – Position connectors near the PCB edges to allow easy access for external cables and peripherals.

 

Ignoring these factors can lead to misalignment issues, loose connections, or even physical damage during assembly.

 

Assembly Constraints:

 

A PCB layout isn’t just about function—it also needs to be easy to manufacture and test. Poor placement of components can lead to soldering defects, longer assembly times, and increased production costs. Best Practices for Manufacturable PCB Designs:

 

• Leave Adequate Spacing – Keep enough distance between components to allow for automated soldering and inspection.

• Avoid Overlapping Components – Ensure no components block others, especially when using surface-mount devices (SMDs).

• Design for Automated Testing – Place test points in accessible locations to facilitate quality checks and debugging.

 

By considering assembly constraints early in the design phase, you can reduce production costs and minimize errors.

 

Component Orientation & Grouping: 

 

For a clean and organized PCB layout, components should be grouped and oriented in a logical manner. Proper orientation ensures that automated machines can efficiently place and solder components. Guidelines for Efficient Component Placement:

 

• Consistent Orientation – Align similar components in the same direction to simplify soldering and reduce placement errors.

• Group by Function – Keep power components together, signal processing components together, and high-speed circuits separate.

• Minimize Crossing Traces – Avoid unnecessary crisscrossing of signal traces, as this can lead to signal interference.

 

Grouping components strategically improves circuit performance, simplifies debugging, and speeds up assembly.

 

 

Reducing Connectivity Complexity: 

 

The way you connect components affects signal integrity, performance, and manufacturability. Complex routing with excessive traces can cause voltage drops, interference, and unnecessary heat buildup. Tips for Effective Routing:

 

• Keep Traces Short & Direct – Shorter traces improve signal strength and reduce noise.

• Minimize Via Usage – Too many vias can increase resistance and cause unwanted signal delays.

• Use a Clear Routing Path – Organize traces in logical paths to prevent congestion and improve troubleshooting.

 

A well-planned routing strategy leads to cleaner PCB designs that perform reliably in real-world applications.

 

Minimizing Electromagnetic Interference (EMI):

 

Electromagnetic interference (EMI) can disrupt signals and degrade PCB performance, especially in high-frequency circuits. Component placement plays a major role in reducing EMI and ensuring stable operation. How to Minimize EMI in PCB Design:

 

• Separate Analog & Digital Components – Keep analog circuits away from digital circuits to prevent signal distortion.

• Shield High-Frequency Components – Use ground planes and shielding techniques for components that generate EMI.

• Avoid Running Traces in Parallel – Parallel traces can cause crosstalk, leading to unwanted interference.

 

By designing with EMI reduction in mind, you can create more stable and noise-free electronic circuits.

 

Thermal Management: 

 

Heat buildup is a common issue in high-power circuits, and poor thermal management can lead to component failure and reduced lifespan. Thermal Management Strategies:

 

• Place Heat-Generating Components Near the Edge – Allows for better airflow and heat dissipation.

• Use Thermal Vias & Heat Sinks – Helps distribute excess heat away from sensitive areas.

• Avoid Placing Heat-Sensitive Components Near Hot Spots – Components like capacitors and microcontrollers should be placed away from power transistors and voltage regulators.

 

Proper thermal design helps ensure that PCBs remain stable and reliable under heavy loads.

 

Power Integrity & Grounding Best Practices: 

 

Stable power distribution and proper grounding are essential for minimizing noise and preventing voltage fluctuations. Power & Grounding Best Practices:

 

• Use a Solid Ground Plane – Reduces electrical noise and provides a stable reference voltage.

• Keep Power & Ground Traces Wide – Ensures low resistance paths for current flow.

• Minimize Loops in Grounding – Prevents ground loops that can introduce unwanted noise.

 

By following these grounding techniques, you can maintain power stability and protect sensitive components from electrical disturbances.

 

 

 

 

PCB Troubleshooting & Testing Methods

 

Even the best-designed printed circuit boards (PCBs) can run into problems. Whether it's a faulty component, a short circuit, or unexpected behavior, knowing how to troubleshoot and test a PCB is essential. In this section, we’ll go over common failures, detection methods, and best practices for debugging circuit boards effectively.

 

Common PCB Component Failures & Symptoms

 

When a PCB isn’t working as expected, the issue often comes down to a faulty component. Here are some of the most common failures and their telltale signs:

 

 

Component	Common Failures	Symptoms
Resistors	Burned out, increased resistance	Overheating, incorrect voltage readings
Capacitors	Leakage, short circuit, or bulging	Power instability, no signal output
Diodes	Open circuit, short circuit, or breakdown	No rectification, reversed polarity issues
Transistors	Faulty switching, overheating	No signal amplification, circuit instability
ICs (Integrated Circuits)	Overheating, damaged pins, internal failure	Malfunctioning logic, dead circuit sections
Connectors & Solder Joints	Loose connections, cold solder joints	Intermittent operation, no power flow

 

 

When you notice these symptoms, it’s time to test and isolate the problem before replacing components.

 

How to Detect Short Circuits: Visual, Multimeter, & Thermal Camera Methods

 

A short circuit occurs when unintended connections allow excess current flow, which can lead to overheating, damaged components, or even complete PCB failure. Detecting short circuits quickly can save a lot of time in troubleshooting. Visual Inspection and What to Look For:

 

• Burn marks or discoloration

• Melted or bulging components

• Solder bridges (unintended solder connections between pads)

• Damaged traces

 

A simple magnifying glass or microscope can help identify tiny shorts that aren’t visible to the naked eye.

 

 

Multimeter Testing

 

A digital multimeter is one of the most useful tools for detecting short circuits. How to Check for Shorts with a Multimeter:

 

1. Set the multimeter to continuity mode (beep sound mode).
2. Place one probe on the ground (GND) line and the other on the suspected shorted component.
3. If you hear a beep, it means there is a connection where there shouldn’t be.

 

Multimeter testing is quick and effective for pinpointing unintended connections.

 

Thermal Camera Detection

 

A thermal camera is a high-tech way to find short circuits by detecting hotspots on the PCB. How It Works:

 

• Power up the board and use a thermal camera to look for overheating spots.

• Shorted components will often heat up faster than normal ones.

• This method is particularly useful for multi-layer PCBs, where shorts aren’t visible on the surface.

 

Pro Tip: If you don’t have a thermal camera, you can use your finger to lightly touch the PCB (carefully!). If a component is abnormally hot, it could be the source of the short.

 

 

Testing Resistors, Capacitors, Diodes, and Transistors

 

Once you've identified potential problem areas, the next step is to test individual components to confirm if they’re faulty.

 

Resistor Testing (With a Multimeter)

 

• Set the multimeter to resistance mode (Ω).

• Place the probes on both ends of the resistor.

• The reading should match the expected resistance value (within tolerance).

• If the reading is infinite (OL), the resistor is open (damaged).

 

Capacitor Testing (With a Multimeter or Capacitance Meter)

 

• Set the multimeter to capacitance mode (if available).

• Place the probes on the capacitor’s leads.

• A dead capacitor will show 0F or no reading.

• For electrolytic capacitors, check for bulging or leakage.

 

Diode Testing (Using the Diode Test Mode on a Multimeter)

 

• Set the multimeter to diode mode (symbol).

• Place the red probe on the anode and black probe on the cathode.

• A working diode should show a low voltage drop (0.5V-0.7V for silicon diodes).

• If the reading is 0V or infinite (OL) in both directions, the diode is faulty.

 

Transistor Testing (Using the Continuity Test Mode)

 

• Identify the base, collector, and emitter pins.

• Use a multimeter to check for expected voltage drops between terminals.

• If the transistor conducts in both directions, it's likely damaged.

 

Testing individual components helps confirm whether the issue lies within a single faulty part or a larger circuit problem.

 

Comparison of Common Components

 

Component	Function	Key Considerations	Applications
Resistors	Limit current and voltage division	Resistance value, power rating, tolerance	Signal conditioning, biasing, voltage regulation
Capacitors	Store and release energy	Capacitance, voltage rating, ESR	Noise filtering, energy storage, coupling
Inductors	Store energy in a magnetic field	Inductance value, core material, current rating	Power regulation, RF circuits, filtering
Diodes	Control current direction	Forward voltage drop, reverse voltage rating, switching speed	Rectification, protection, LEDs, modulation
Transistors	Amplify and switch signals	Gain, voltage rating, switching speed	Amplification, switching, voltage regulation
Microcontrollers	Process digital instructions	Clock speed, memory size, power consumption	Embedded systems, automation, IoT
Crystals/Oscillators	Generate clock signals	Frequency stability, load capacitance	Timing in microprocessors and communication
Relays	Electrically controlled switches	Voltage and current rating, switching speed	Power control, automation, industrial systems
Connectors	Establish electrical connections	Pin configuration, durability	Power supply connections, data transfer
Sensors	Detect physical changes	Sensitivity, response time	IoT, environmental monitoring, automation

 

 

FAQs About PCB Components and Functions

 

 

 

Summary

 

 

The history of components used in the circuit goes back to the late 1900s and has been shaped by continuous development and new innovations with the advancement in technology. PCBs were made from materials like Bakelite, Masonite, cardboard sheets and a thin wooden plank in olden days. Invention of passive components like resistor, capacitor and inductor were done during the 19th century. Later on in the 20th century vacuum tubes were introduced and transistors replaced these bulky vacuum tubes. With all the developments on the components and circuit boards, introduction of Integrated circuits (IC’s) revolutionized the electronic industry by enabling compact sized components and devices.

 

In the 1980s surface mount technology (SMT) was introduced which further reduced the circuit board components size and made assembly process easier. With the introduction of microcontrollers and microprocessor IC’s in 1970-1980, capability of electronic devices were improved and went to a whole new level. In today’s world of electronic industry surface mount devices (SMD) has become a standard technology. Over the several years, evolution of components has enabled the PCB to bring down the size to miniature level without losing the electrical performance and has helped to develop more efficient and powerful devices that are used worldwide.

 

Printed circuit boards (PCBs) are the heart of any modern electronic device which provides mechanical support for electronic components. With the evolution of components used in circuit boards over several years, it is essential for everyone involved in PCB design, manufacturing and the assembly process to understand the characteristics of the components better. In this article, let us understand a few of commonly used components in the circuit board industry and their applications, functions and the importance of using those in electronic devices.

 

These are the circuit board components that are used widely and very frequently in the circuit board industry all over the world to produce an error free electronic product. Selection of appropriate components purely depends on the kind of application, environmental parameters, characteristics of the components and many more. It is very crucial to select the correct circuit board components in order to make the product reliable and durable.

 

 

 

Written by Icey Ye from AIChipLink.

 

AIChipLink, one of the fastest-growing global independent electronic component distributors in the world, offers millions of products from thousands of manufacturers, and many of our in-stock parts is available to ship same day.

 

We mainly source and distribute integrated circuit (IC) products of brands such as Broadcom, Microchip, Texas Instruments, Infineon, NXP, Analog Devices, Qualcomm, Intel, etc., which are widely used in communication & network, telecom, industrial control, new energy and automotive electronics. 

 

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