Without SMT, modern electronics would be slower to build, less compact, and far more expensive to produce.
Surface Mount Technology (SMT) enables fast, high-density PCB assembly by placing components directly onto board surfaces, reducing cost and improving performance.
From smartphones to medical devices, OEMs rely on efficient PCB assembly to meet design, performance, and volume demands. Surface Mount Technology (SMT) makes that possible—speeding up production, shrinking product size, and enabling the electronics industry to scale. In this article, we’ll break down what SMT is, how it works, and why it’s critical for OEMs building next-generation electronics.
What is SMT?
Surface Mount Technology (SMT) is a method used to mount electronic components directly onto the surface of a Printed Circuit Board (PCB) without the need for drilling holes through the board, unlike traditional through-hole technology.
Since becoming mainstream in the 1980s, SMT has become the industry standard in electronics manufacturing due to its automated nature, which reduces both labor costs and production time. SMT enables manufacturers to use smaller, lighter components and achieve much higher component density, which is essential for modern compact devices.
With the ability to place components on both sides of the board, SMT significantly improves space utilization and design flexibility. The method also supports the development of high-speed, high-frequency circuits that are essential in today’s consumer electronics, automotive systems, and IoT applications.
📖 Learn more about SMT technology from IPC — Association Connecting Electronics Industries
What is the Typical SMT Process?
The SMT process is highly standardized and consists of three primary stages: solder paste printing, component placement, and reflow soldering. Each stage requires precision, specialized machinery, and strict quality control to ensure consistent assembly output.
Solder Paste Printing
The first step involves applying solder paste—a mixture of powdered solder and flux—onto the pads of the PCB using a stainless steel stencil. A solder paste printer performs this operation using squeegees that spread the paste across the stencil openings.
✅ Why it matters:
- Ensures strong electrical/mechanical bonds
- Determines the success of the subsequent reflow soldering step
- Poor paste application can lead to solder bridges, open joints, or tombstoning defects
To maintain process stability, most modern solder printers come equipped with automated inspection systems. Additionally, 3D solder paste inspection (SPI) machines are used to measure solder volume, shape, and positioning on each pad, offering more reliable detection of printing issues than traditional 2D methods.
🛠️ Read more about SPI equipment at Koh Young Technology
Components Placement
Once the PCB passes the printing inspection, it moves to the pick-and-place machine, where individual components are precisely positioned onto the board.
Advanced machines use high-speed vision systems and robotic arms to place thousands of components per hour—up to 80,000 placements/hour in high-volume lines. The system draws components from reels or trays using vacuum nozzles and aligns them onto their exact pad locations.
After placement, another inspection is conducted to verify the accuracy and orientation of each component. Mistakes at this stage can be costly, requiring rework or resulting in functional defects.
🧠 For a deeper understanding of pick-and-place systems, see Mycronic’s SMT Equipment Guide
Reflow Soldering
The final phase of the SMT process is reflow soldering, where the PCB is passed through a reflow oven. Here, temperature-controlled zones gradually heat the board to a point where the solder paste melts and forms permanent joints between components and pads.
The reflow profile is critical:
- Too hot can damage components or warp the PCB
- Too cold results in incomplete soldering and weak connections
Most systems use a conveyor-fed oven with multiple zones:
- Preheat Zone: Gradual temperature ramp-up
- Soak Zone: Stabilizes heat across the board
- Reflow Zone: Peaks the temperature to melt solder
- Cooling Zone: Solidifies joints without thermal stress
Post-reflow, a 3D Automated Optical Inspection (AOI) system scans the board for solder joint defects like cold joints, solder bridges, and misalignments. These machines offer high-speed, repeatable results and outperform manual inspections in high-throughput environments.
📷 More about reflow soldering best practices at Nordson EFD
How is custompcba Different?
Tailored OEM Services
At custompcba, we specialize in providing end-to-end PCB manufacturing solutions tailored to the needs of OEMs across industries. Whether you need a full turnkey assembly service or support with a single stage of the process, our team offers flexible engagement models and technical support at every step.
Family-Driven Values with Global Capabilities
Started as a small family-run operation, custompcba remains rooted in family values while operating on an international scale. Our leadership team brings decades of industry knowledge, combining personal service with cutting-edge automation.
We believe relationships matter—when you work with us, you’re treated like a partner, not just another purchase order.
20+ Years of Experience and Vertical Integration
With over three decades of experience, custompcba offers comprehensive in-house capabilities from prototyping to full-scale manufacturing. Unlike many PCB suppliers who outsource parts of the process, we handle:
- PCB fabrication
- SMT assembly
- Testing and inspection
- Packaging and logistics
This integrated approach results in:
- Better control over timelines
- Enhanced quality consistency
- Greater cost efficiency
🔎 Explore our manufacturing workflow
Budget Flexibility Without Compromising Quality
We understand that no two customers are the same. Whether you’re a growing SME or a global tech leader, we work closely with your team to deliver solutions within your budget constraints—while never sacrificing technical quality.
Our transparent pricing model ensures you understand what you’re paying for, and our engineers are happy to help optimize designs for cost-effective manufacturability (DFM).
Final Thoughts
Surface Mount Technology has reshaped electronics manufacturing by offering greater efficiency, higher component density, and improved reliability. From prototyping to volume production, mastering SMT is vital for OEMs looking to maintain competitiveness and accelerate time to market.
At custompcba, we bring together deep expertise, full in-house capabilities, and a customer-first approach to deliver precise, scalable SMT solutions. If you’re planning your next product and want a reliable, experienced assembly partner—we’re ready to help.
📧 Get in touch: info@custompcba.com
