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How do Circuit Boards Work? Explanation into PCBs and Their Different Parts
Jessica Hopkins

Printed circuit boards (PCBs) are essential components in embedded engineering. They provide an organized platform for integrating electronic components that is used to develop various types of electronic devices. Each interconnected component on a PCB plays a critical role in determining an electronic device’s functionality and performance. In this blog, we’ll provide insight into what printed circuit boards are, their different components, different types, and what role they play in the world of embedded systems.

What is a Printed Circuit Board (PCB)?

A PCB is a flat board made of non-conductive material, such as fiberglass or epoxy, with thin layers of conductive copper traces etched onto its surface. While circuit boards can be made manually via soldering techniques, the term "printed" in PCB refers to the process of creating the circuit pattern on the board's surface using a combination of printing and chemical etching techniques. Various components like resistors, capacitors, transistors, and integrated circuits (ICs) are mounted onto the surface of the PCB and connected to the copper traces through soldering. These copper traces allow signals to flow between components, enabling the device to perform its dedicated function.


green circuit board with integrated circuits Image by Andreas Lischka from Pixabay

PCBs are used in a wide range of electronic devices we use daily, including smartphones, computers, medical devices, automotive systems, industrial equipment, and much more.

What Role Does a Printed Circuit Board (PCB) Play in Embedded Systems?

PCBs are the backbone to electronic devices as they aid in enabling their operation and functionality.

Pathway for Electrical Signals

One primary function of a PCB in an embedded device is to facilitate the transmission of electrical signals between components mounted on the board. These signals traverse along copper pathways, conveying data and instructions and enabling the exchange of information.

Components of a Printed Circuit Board

Different PCB components work together to form functional electronic circuits. The specific components used depends on the device's functionality, design requirements, and performance specifications. Certain components often seen on a PCB can include:

Passive components such as resistors, capacitors, and inductors that are used for signal processing, filtering, and voltage regulation. Active components such as integrated circuits (ICs) that include microcontrollers or memory chips, as well as transistors to act as switches or amplifiers, and diodes to control the direction of current flow. Connectors and interfaces such as headers to provide connection points to other wires or PCBs and interface connectors such as USB or HDMI ports. Power management components such as voltage regulators to stabilize and regulate voltage levels in a circuit.

Sensors and actuators to help facilitate responsive interactions, that include detecting physical or environmental conditions like temperature or converting electrical signals into physical actions.

PCB Communication

All together, these components and electrical signals establish the framework for communication and data exchanges, fostering connectivity between each element and enabling the device to fulfill its intended role. These components may utilize protocols like SPI, or I2C, or UART to exchange data efficiently and reliably, ensuring the proper operation and performance of the electronic device. A simple example of communication between components on a PCB could include the interaction between a central processing unit (CPU) and an SPI EEPROM. A CPU communicates with an SPI EEPROM by addressing the EEPROM, specifying the memory location to access, and then reading or writing data as needed, facilitating the storage or retrieval of information between the CPU and the EEPROM.

Types of Printed Circuit Boards

There are various types of PCBs, each designed for specific purposes or applications. Some common types include:

Single-sided PCBs:

  • Feature conductive traces on one side, commonly used in simpler electronic circuits due to their cost-effectiveness and ease of manufacturing.
  • Often used in applications including calculators, radios, and LED lights.

Double-sided PCBs:

  • Have conductive traces on both sides, enabling more complex circuit designs and higher component density compared to single-sided PCBs.
  • Due to their versatility, these are often used in applications such as mobile phones, printers, routers, and modems.

Multi-layer PCBs:

  • Comprise three or more layers of conductive traces separated by insulating layers. These boards offer increased circuit density, reduced size, and enhanced performance, making them suitable for more advanced electronics.
  • Common applications include computers, laptops, server motherboards, and advanced medical equipment such as MRI machines.

Rigid PCBs:

  • Constructed using solid, inflexible materials like FR-4, providing stability and mechanical support for electronic components.
  • They are standard in most electronic devices where rigidity is essential such as home electronics (TVs, DVD players), and consumer electronics (smartphones, cameras).

Flexible PCBs (Flex PCBs):

  • Made of materials such as polyimide, allowing them to bend or flex without damage.
  • Flex PCBs are ideal for applications requiring compact, lightweight, or bendable designs such as wearable electronics (smartwatches), as well as foldable smartphones or curved displays.

Rigid-Flex PCBs:

  • Combine rigid and flexible substrates into a single board, offering the benefits of both types. They enable complex three-dimensional layouts, reduce assembly time, and improve reliability.
  • These PCBs are commonly used in military equipment, aerospace, medical devices, and more.

PCBs in Our Electronics Today

Over the years, circuit boards have undergone significant transformations, evolving from basic designs with simple wiring to intricate structures with multiple layers and compact components. Thanks to advancements in surface-mount technology, circuit boards now benefit from automated assembly and high-density compatibility, resulting in the large-scale production of smaller, more compact boards. These benefits have resulted in smaller but more powerful devices across various industries, from consumer electronics to aerospace and medical applications.

Prototyping and Testing PCB Designs

During the development and testing phases of manufacturing today’s electronic devices, engineers may often use host adapters for system emulation and protocol analyzers for monitoring data transmission between components on a PCB. These tools aid in debugging and optimizing system performance.

Total Phase offers both host adapters and protocol analyzers that support I2C and SPI protocols. Host adapters can be used to emulate master and slave devices to test a system’s validity - including testing and observing CPU/MCU communication with sensor devices. It also allows users to perform rapid prototyping of systems or quickly program EEPROM or Flash memory devices.

Our I2C/SPI Host Adapters include:

View our I2C/SPI Product Guide for a comparison of these tools.

We also offer the Beagle I2C/SPI Protocol Analyzer that allows users to non-intrusively monitor I2C or SPI data on the bus in real time while flagging bus errors for easy debugging.

In addition, we also offer CAN tools to actively transmit and monitor CAN data, and an extensive line of USB protocol analyzers to debug Full-Speed, High-Speed, and SuperSpeed USB data with options for advanced triggers.


In summary, PCBs are critical to the advancement of modern electronics. PCBs are not only essential to the foundation of electronic devices, they enable devices to operate as intended. As advancements in electronic design continue to evolve, understanding the role of PCBs remains essential in shaping the future of technology.

For more information on how our tools can help debug and develop your embedded systems, please email us at sales@totalphase.com.