THT vs. SMT assembly techniques: comparison and applications

In electronics manufacturing, there are two main approaches to assembling printed circuit boards – Through-Hole Technology (THT) and Surface Mount Technology (SMT). Each of these methods has its own unique advantages and challenges that determine their applications in different areas. In our article, we discover when and why to choose THT versus SMT, and the benefits of these techniques. Read on to learn more about the key differences and practical applications of the two PCB assembly technologies.

PCB assembly

The assembly of components on PCBs is crucial to the production of electronic devices. The two main techniques are Through-Hole Technology (THT) and Surface-Mount Technology (SMT). Each of these methods has its own specific advantages and limitations, which determine their application in different areas. In this article, we will examine the two technologies in detail, compare their functionality and indicate where they perform best.

THT technology 

THT, or through-hole assembly technology, involves placing electronic components on a PCB using wires that pass through holes in the board and are soldered on the other side.

THT advantages:

• The mechanical durability of THT components is higher because they are more firmly embedded on the PCB. This makes them more resistant to vibration and mechanical forces, which is crucial in rugged applications such as industrial, military, and medical devices. Additionally, the solid embedding of components makes them more reliable in harsh environments.
• The ease of repairing THT components is due to their larger size and easier access. This makes repairs and modifications simpler, reducing service time and costs. This feature is particularly important in prototyping and small batch production, where frequent changes and modifications are common.
• The better thermal properties of THT components mean they are more resistant to overheating. Heat conduction through the component to the PCB helps dissipate heat, which is beneficial in applications that require high currents or generate a lot of heat.

THT disadvantages:

• The larger size and weight of THT components can be problematic in modern miniaturized devices. THT components are generally larger and heavier than their SMT counterparts, limiting the potential for device miniaturization. Modern trends in electronics emphasize compactness and lightweight, making THT not always the optimal choice. 
• The higher manufacturing costs associated with THT technology stem from its more labor-intensive assembly process. The frequent necessity for manual soldering of components in low-volume orders increases production time and costs. This process is also more challenging to automate, which can result in greater quality variability.
• The lower component density of THT restricts the number of components that can be placed on a printed circuit board. Compared to SMT, THT allows fewer components to be positioned in the same area, which can be a limitation in designs requiring a large number of components.

SMT technology 

SMT, or surface mount technology, involves mounting components directly on the PCB surface without drilling holes.

SMT advantages:

• The compact size of SMT components allows the development of more compact and high-tech devices, such as smartphones, tablets and wearable devices like smartwatches and fitness bands. With smaller and lighter components, more efficient use of PCB space is possible.
• Automated SMT manufacturing significantly reduces production costs and increases productivity. The assembly process is highly automated, which minimizes the risk of human error and improves the quality of final products.
• The higher density of SMT components makes it possible to put more components on a smaller PCB area. This is crucial in modern electronics applications, where every square millimeter of space counts, allowing the design of devices with more advanced features.
• The improved electrical performance of SMT components resulting from shorter connections between components can improve the electrical performance of devices, reducing signal losses and increasing processing speed.

SMT disadvantages:

• Difficulties in repairing SMT components arise from their smaller size, making repairs and modifications more difficult. This requires specialized equipment and higher technical skills, which can increase service costs.
• High-precision assembly in SMT technology is essential, which can pose a challenge in low-volume production or prototype conditions. The assembly process requires very high precision, which can be difficult to achieve without advanced equipment.

Applications of THT assembly technology

THT technology has specific applications due to its unique advantages, such as high mechanical durability and ease of repair.

1. Industrial equipment:

• PLCs (Programmable Logic Controllers) often use large electrolytic capacitors, relays, and transformers. These components are firmly seated, which increases their resistance to vibration and shock.
• Sensors and control devices, such as temperature sensors, pressure sensors, and relays, have better resistance to environmental conditions, including high humidity and dust.

2. Military equipment:

• Communication systems, such as military radios, use connectors, antennas, large capacitors, and coils. These components provide high reliability and ease of repair in field conditions.
• Navigation and control systems often use potentiometers, relays, and LED displays. These components can withstand extreme environmental conditions, such as high temperature and shock.

3. Medical devices:

• MRI scanners and CT scanners use large power supplies, transformers, and high-voltage connectors. These components provide precise connections and high reliability, which is essential in diagnostic equipment.
• Patient monitoring equipment is often equipped with connectors for sensors and large capacitors. This makes these devices easy to service and their components easy to replace.

4. Prototypes and small production runs:

• New product development often relies on universal PCBs and components that are easy to modify. This facilitates rapid prototyping and easy design verification.
• Experimental designs typically utilize connectors, relays, and large capacitors. These components enable easy modification and adaptation to different applications, which is crucial during the testing of new solutions.

Applications of SMT assembly technology

SMT technology is preferred for the mass production of modern electronic devices due to its ability to miniaturize and automate.

1. Consumer devices:

• Smartphones use microprocessors, NAND memories, and RF integrated circuits. High assembly density allows integration of many functions into a compact form factor, which is crucial for modern phones. 
• Computers and laptops incorporate RAM, processors, and GPU chips. SMT technology makes it possible to produce thin and lightweight devices with advanced computing capabilities, which is important for mobility and productivity.
• TVs are equipped with image processing chips, HDMI connectors, and ceramic capacitors. SMT technology reduces the size and weight of these devices while improving their thermal performance.

2. Wearable electronics:

• Smartwatches use microprocessors, sensors, and lithium-ion batteries. Miniaturization of these components makes it possible to produce lightweight and ergonomic devices that are comfortable to wear every day.
• Fitness bands are equipped with accelerometers, gyroscopes, and Bluetooth modules. This makes it possible to integrate many health functions in a small and convenient format, making them ideal tools for monitoring physical activity.

3. Advanced technological devices: 

• Drones are equipped with flight controllers, brushless motors, and LIDAR sensors. The low weight and high energy efficiency of these components are crucial for long flight durations. 
• Robotics uses motor controllers, encoders, and communication circuits. Compact circuits enable advanced functions in both industrial and consumer robots, enhancing their functionality and efficiency.

4. Home automation and the Internet of Things (IoT):

• Smart home devices such as thermostats and lighting systems use Wi-Fi modules, microcontrollers, and temperature sensors. SMT technology enables the creation of sleek, integrated solutions that are easy to install and operate, enhancing user comfort. 
• IoT sensors and controllers utilize ZigBee modules, LoRa communication chips, and low-power consumption batteries. The compact size of these components allows them to be installed in various locations, providing a wide range of IoT applications, from smart homes to industrial monitoring systems.

How do you choose the right installation technology for your project?

The choice between THT and SMT technology depends on the specific requirements of the project. THT technology, with its higher durability and ease of repair, is ideal for industrial and prototyping applications where reliability and durability are crucial. On the other hand, SMT technology allows for miniaturization and automation of production, which is essential in modern consumer devices such as smartphones, computers, and smart home appliances.

The decision to choose the right technology should be based on an analysis of the advantages and disadvantages of both PCB assembly methods to best match the solution to the specific needs of your project.

If you are looking for reliable THT and SMT assembly solutions for prototypes or production devices, we invite you to take advantage of our services at Device Prototype. We offer professional consulting and project implementation using the latest technology to meet all your technical and quality requirements. Contact us to learn more and start cooperation!