SMT Assembly: A Powerful Technique for Electronics Assembly
Surface Mount Technology (SMT) assembly is a powerful technique in electronics assembly that makes it possible to create smaller electronic devices while boosting efficiency and lowering the cost of assembling printed circuit boards (PCBs). This blog will explain SMT assembly and explore the advantages of SMT over other methods, how automated SMT assembly lines work and the many products the technique enables.
What is Surface Mount Technology (SMT)?
Surface Mount Technology, or SMT, assembly is a specialized process for soldering electronic circuit boards by mounting components directly onto the surface of a PCB.
SMT vs. Through-Hole Technology
SMT was developed to replace traditional through-hole technology, which is a costly and time-consuming method. In SMT technology, the components are soldered directly onto the surface of the circuit board. In through-hole assembly, the component leads are passed through holes that are drilled in the circuit board.
The SMT method is more efficient and cost effective and allows for smaller component sizes and higher component densities, which facilitates the smaller, lighter and more powerful electronic devices we use today.
The Automated SMT Assembly Process: Step-by-Step
SMT assembly lines use a multi-stage process that is highly automated and relies on tight quality control.
What Equipment is Used in SMT Assembly?
Step 1: Solder Paste Printing
What it is: A sticky mixture of solder particles, flux and additives (solder paste) is applied to the PCB.
Equipment used: A stencil is used to apply the paste in a precise pattern for component placement.
Step 2: Component Placement
What it is: Components are placed onto the solder paste on the PCB.
Equipment used: Automated pick-and-place machines perform this step at high speed.
Key technology: Precision is achieved using integrated machine vision and motion control systems.
Step 3: Reflow Soldering
What it is: The solder paste is melted to create permanent electrical connections.
Equipment used: The PCB passes through a reflow oven (or soldering machine) with tightly controlled temperatures that melt the paste, which then cools and solidifies.
Step 4: Inspection and Testing
What it is: The newly assembled PCBs are inspected to ensure quality and functionality.
Equipment used: Automated inspection systems, such as Automated Optical Inspection (AOI), use machine vision to detect defects like poorly aligned components or insufficient soldering.
Key Automation Components for SMT Assembly
JHFOSTER offers the core automation technologies needed to power a SMT assembly line’s precision, speed and reliability.
Robotics
Robotics are the heart of the SMT line.
Pick-and-place robots: SCARA robots are frequently used for their high speed and precision in picking electronic components and placing them accurately on the PCB.
Robotic accessories: End-of-arm tooling (EOAT) is critical for handling tiny, delicate components.
Motion Control
Exacting motion control is essential for the precise, high-speed movement of pick-and-place machines and inspection systems.
Servo motors and drives: Servo motors and drives provide precise, controlled and repeatable motion for robotic arms and placement heads.
Electric actuators & linear bearings: Electric actuators and linear bearings enable smooth, low-friction and accurate linear motion for moving PCBs through the line or positioning inspection cameras.
Sensors & Machine Vision
Machine vision is critical for both component placement and post-assembly inspection.
Sensors and ID: These technologies are used to detect the presence and orientation of PCBs (presence sensors) and track them through the process (barcode/RFID).
Vision systems: Advanced cameras and AI-capable systems inspect for solder paste accuracy, component alignment and solder joint quality after reflow.
Control Systems
Control panels & PLCs: These systems serve as the brain of the SMT line, coordinating the robots, motion control and sensors to ensure all steps happen in the correct sequence.
6 Industries with Devices Made via SMT Assembly
SMT is highly automated, which enables efficient, high-volume production of smaller, more powerful and highly reliable electronic devices. It has advantages over traditional through-hole assembly, which is costly and error prone.
Because SMT is so widely adopted, many modern electronic devices contain components made on SMT assembly lines, as shown in the table below.
| Industry | Devices | SMT Benefits |
| Consumer Electronics | Smartphones, laptops, tablets, smartwatches | SMT fits smaller components into less space for better processing power and battery life. |
| Medical Devices | Pacemakers, hearing aids, glucose monitors | SMT enables lightweight, compact and reliable designs that meet strict safety and performance requirements. |
| Automotive Features | GPS/navigation, driver assistance systems, entertainment systems, EV battery management components | SMT provides compact and reliable electronic modules. |
| Telecommunications | Modems, wi-fi routers, IoT gateways and modern network infrastructure | SMT enables smaller, more reliable devices. |
| Industrial Electronics | Sensors, PLCs, robotic controllers, HMIs | SMT enables smaller, reliable devices to suit modern industrial automation requirements. |
| Aerospace and Defense | Avionics, navigation, radar systems | SMT provides miniature, lightweight and highly reliable electronics for critical systems. |
Partner with JHFOSTER for Your Automation Needs
SMT assembly has transformed electronic device design, enabling compact, reliable components with more processing power. It saves manufacturers time and money while increasing the reliability of today’s electronics.
The precision, reliability and efficiency of SMT assembly are all powered by advanced automated systems, machine vision and robotics. To learn more about the automation and vision systems used in modern manufacturing, contact JHFOSTER today or request a quote.
