SMT and SMD are common terms in electronics manufacturing—but what is the difference between SMT and SMD, and how does each term apply in practice?

SMT (Surface Mount Technology) is the method used to mount components onto a PCB, while SMD (Surface Mount Device) refers to the actual components that are mounted using that method.

If you’re new to PCB assembly or reviewing datasheets, you’ve likely come across the terms SMT and SMD. They’re often used interchangeably, but they’re not identical. Understanding the difference is essential for designers, buyers, and engineers who want to communicate clearly and avoid costly production errors.

Let’s dive into what each term actually means, how they relate to each other, and why the distinction matters in PCB design and assembly.

What Is SMT?

SMT, or Surface Mount Technology, is a method used to mount electronic components directly onto the surface of a printed circuit board (PCB). Unlike the older through-hole method, SMT doesn’t require drilled holes for component leads.

The SMT process includes:

• Applying solder paste
• Placing SMDs with a pick-and-place machine
• Passing the board through a reflow oven to secure the components

SMT allows for higher density, smaller components, and faster assembly, making it the default method for modern electronics manufacturing.

To see the SMT process in action, check out this step-by-step overview by Circuit Digest.

What Is SMD?

SMD, or Surface Mount Device, is the physical component used in the SMT process. These components are designed with flat metal contacts or small leads that sit directly on the PCB surface.

Common SMDs include:

• Resistors (e.g., 0603, 0805)
• Capacitors
• Diodes
• ICs (Integrated Circuits)
• LEDs and transistors

SMDs are generally smaller than their through-hole counterparts, allowing more parts to fit on a board, which is especially important in smartphones, wearables, and IoT devices.

For SMD package dimensions and standards, visit this SMD codebook reference.

How Are SMT and SMD Related?

Think of it this way:

• SMT is the method (how components are mounted)
• SMD is the component (what is being mounted)

You can’t use SMD components without SMT, and SMT only works with SMDs. They go hand in hand, but refer to different parts of the assembly equation.

In a production environment, SMT is a process performed by machines and operators, while SMDs are listed in the BOM (Bill of Materials) and handled during placement.

Key Differences Between SMT and SMD

Here’s a quick side-by-side comparison to clarify:

Feature	SMT (Surface Mount Technology)	SMD (Surface Mount Device)
Definition	Assembly method	Type of component
Refers to	The process	The part
Usage	Pick & place, soldering steps	Resistors, ICs, capacitors, etc.
Involved in Design	Manufacturing planning	Electrical BOM and circuit layout
Requires Holes?	No	No

Why It Matters in Manufacturing

Understanding the difference between SMT and SMD helps avoid miscommunication during:

• PCB design and layout planning
• Procurement and BOM creation
• Communication with EMS (Electronics Manufacturing Services) providers

For example, telling a supplier you need “SMT components” might confuse them. You mean SMDs—they’re the parts, SMT is the process.

Additionally, some DFM (Design for Manufacturability) tools and software distinguish clearly between SMT layer design and SMD component footprints. Mixing up the terms can lead to wrong footprint selection or even assembly delays.

For smoother production, always use the terms correctly when preparing design files and communicating with your contract manufacturer.

Conclusion

The terms SMT and SMD are closely related but refer to different aspects of PCB assembly. SMT is the process used to place and solder components, while SMD is the type of component designed for that process.

By understanding and using these terms accurately, you’ll ensure better collaboration with manufacturers, cleaner design documentation, and fewer issues during production.

In short: SMT does the job. SMD is the thing being worked on.