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COM Express is a widely adopted computer-on-module (COM) standard in embedded systems. Overseen by the PCI Industrial Computer Manufacturers Group (PICMG), this specification defines a versatile, modular approach to embedded system design. This translates to benefits like scalability, flexibility, and a streamlined development process – all crucial aspects for engineers working on demanding projects.

What Is COM Express?

COM Express is a standardized format for computer-on-modules (COMs). These compact, self-contained units integrate core computer functions like CPU, memory, storage interfaces, and networking – essentially miniaturized computers. They’re designed to seamlessly work with a carrier board (a base board with support components paired with modules). This separate carrier board, customized for each application, provides the necessary Input/Output (I/O) interfaces, power supply, and any additional functionalities the final product requires.

Key Features and Benefits

COM Express modules shine in embedded system design, offering a compelling set of advantages for engineers:

  • Scalability: Future-proof your designs! COM Express allows for upgrading core processors, memory, and storage. This flexibility is particularly valuable considering the rapid pace of technological advancements, especially in demanding fields like military and aerospace.
  • Customization Power: COM modules act as the foundation, while the magic happens on the custom carrier board. This modular approach empowers engineers to tailor I/O interfaces, power supplies, and functionalities to match each project’s unique requirements precisely.
  • Faster Development Cycles: Pre-designed COM modules act as a head start, allowing engineers to channel their expertise into optimizing the carrier board. This translates to quicker development cycles that keep projects on track.


COM Express offers a high degree of flexibility through various module types, each defined by PICMG to address specific application needs. These types provide distinct combinations of pin configurations and features, empowering engineers to select the optimal COM Express module for each project.

  • Type 1: This type features a single connector with a basic set of I/O interfaces, suitable for applications requiring moderate performance and connectivity.
  • Type 2: Expanding on Type 1, Type 2 offers two connectors for increased I/O options, making it ideal for bridging older and newer technologies.
  • Type 6: A widely used type known for its extensive support for modern interfaces like multiple Peripheral Component Interconnect Express (PCIe) lanes, USB 3.0, Serial Advanced Technology Attachment (SATA), and advanced video outputs. This makes Type 6 suitable for applications requiring high-speed connectivity and graphics capabilities.
  • Type 7: Designed for server-grade performance, Type 7 prioritizes high-speed networking and data transfer with features like multiple 10 Gigabit Ethernet (10 GbE) ports and Non-Volatile Memory Express (NVMe) storage support.
  • Type 10: This compact version of Type 1 offers a subset of interfaces in a smaller form factor, making it perfect for space-constrained applications where size and power consumption are critical.
  • Type 11: Building on Type 6, Type 11 boasts additional support for newer interfaces and higher performance requirements, catering to applications demanding the latest technology and advanced I/O options.

By understanding the strengths of each COM Express type, engineers can make informed decisions when selecting the most suitable module for their specific embedded system design needs.


COM Express modules boast rich interfaces, empowering engineers to design highly versatile systems. This variety ensures compatibility with a broad range of carrier boards, a key aspect for customization in embedded system design. Common interfaces include PCI Express (PCIe) for high-speed data transfer, USB for connecting peripherals, SATA for storage devices, and Ethernet for networking. This flexibility allows engineers to tailor the functionality and connectivity of the final system to match project requirements precisely.


There’s a variation known as Server-on-Module for applications demanding serious processing muscle. This concept takes the foundation of COM Express and injects it with steroids, packing server-grade processors and features. The result is high-performance computing solutions ideal for data-intensive tasks like edge computing and real-time data processing often encountered in demanding fields like aerospace and military engineering. Server-on-Module solutions combine COM Express’s flexibility with the power of server-class hardware, giving engineers more processing horsepower and advanced I/O options to tackle complex projects.


The magic of COM Express truly shines in its customizability. Unlike traditional fixed-function modules, COM Express separates the core functionalities (processor, memory) from the I/O interfaces and power supply. This separation empowers engineers to design the carrier board – essentially the system’s backbone – specifically for each project’s unique needs. This flexibility translates to several advantages:

  • Tailored Functionality: Unique features can be integrated directly onto the carrier board, adding application-specific functionalities that wouldn’t be available in a pre-built module.
  • Optimized Layout: Engineers can optimize the physical layout of the carrier board to fit size and space constraints, which is a critical feature in many aerospace and military applications.
  • Seamless Integration of Specialized Components: The modular approach allows for the integration of specialized components that may not be readily available in standard COM Express modules.

This level of customization empowers engineers to develop truly bespoke embedded systems that perfectly match the demanding requirements of some projects.


COM Express caters to a wide range of applications by offering modules in various standardized sizes. This variety empowers engineers to select the optimal form factor that balances performance, power consumption, and space constraints – all vital in designing embedded systems for demanding environments. The most common sizes include:

  • Basic: 95mm x 125mm (ideal for applications requiring more processing power and functionalities)
  • Compact: 95mm x 95mm (a good balance between size and capabilities)
  • Mini: 84mm x 55mm (perfect for space-constrained applications where compactness is paramount)

It’s worth noting that these are just the most frequently used options. The PICMG specification offers additional sizes like Nano and Extended, providing even more flexibility for specialized needs.

Thermal Design

Taming the heat is paramount for reliable COM Express operation, especially when dealing with high-performance modules or harsh environments like those encountered in aerospace and military applications. Here’s where thermal design comes into play. This involves strategically incorporating heat spreaders, heat sinks, and potentially active cooling solutions. By carefully considering thermal management, engineers can ensure that COM Express modules operate within safe temperature ranges. This safeguards performance and extends the lifespan of these critical components, providing long-term reliability in challenging projects.

COM Express has undeniably established itself as a powerful and versatile standard for embedded system design. Its core strengths lie in scalability, flexibility, and seamless integration – all important considerations for engineers developing robust solutions. The modular approach empowers them to tailor systems to specific project needs, ensuring optimal performance and functionality and the ability to upgrade COM modules to future-proof designs, extending their usability over time.

The widespread adoption of COM Express across various industries signifies its reliability and efficiency as an embedded computing solution. Notably, within demanding fields like aerospace and military engineering, COM Express shines due to its ability to handle complex tasks and harsh environments.

If you’re a design or product engineer looking to leverage the advantages of COM Express in your next project, consider partnering with a company like Rigel Engineering. Our expertise in custom carrier board design and rugged system development, coupled with our understanding of COM Express, allows us to deliver high-performance, application-specific solutions tailored to your unique requirements. Contact our team to discuss how we can optimize your design with a custom carrier board or COM Express SBC module.

Frequently Asked Questions:

What is the COM Express standard?

The COM Express standard is a set of specifications defined by the PCI Industrial Computer Manufacturers Group (PICMG) that outlines the physical and electrical requirements for computer-on-modules. This standard ensures interoperability, scalability, and long-term availability of embedded computing solutions.

How do COM Express modules and carrier boards work together?

COM Express modules provide the core computing functions, including the CPU, memory, and essential interfaces, while the carrier board provides additional I/O interfaces, power supply, and application-specific functionality. This modular approach allows for easy upgrades and customization.

What are the common applications of COM Express?

COM Express modules are used in a wide range of applications, including industrial automation, medical devices, transportation systems, and telecommunications. Their flexibility and scalability suit any embedded system requiring robust and reliable computing power.

Can COM Express modules handle high-performance applications?

Yes, especially with the introduction of Server-on-Module solutions, COM Express can handle high-performance applications that require server-grade processing power and advanced I/O capabilities. This makes them suitable for data-intensive tasks and real-time processing needs.