Surface Mount Technology (SMT) is essential for assembling Printed Circuit Boards (PCBs) used in a wide range of electronic products. In this blog, we’ll delve into the advantages and disadvantages of SMT to provide product designers, engineers and purchasing managers with the insights needed to determine when this technique is the optimal choice for your projects. Understanding the nuances of SMT empowers you to make well-informed decisions, ensuring that your PCB assembly meets both performance and cost requirements effectively.
Advantages of Surface Mount Technology
The numerous advantages of Surface Mount technology make it the most widely adopted technique used by Contract Electronic Manufacturers (CEMs):
- Compact size – SMT components are smaller, allowing for higher component density on PCBs;
- Cost-effective – lower material costs and efficient automated assembly reduce overall production costs;
- Higher speeds – automated placement is faster, enabling high-volume production;
- Design flexibility – SMT allows components to be mounted on both sides of the PCB.
- Better electrical performance – shorter connections result in reduced signal delay and more reliable performance at high frequencies;
- Reduced weight – lighter components make SMT ideal for portable and miniaturised devices, such as smart watches and hearing aids;
- Automated process – fewer manual steps mean improved consistency and reliability in production. This reduces human error, lowers the risk of defects and significantly decreases the need for rework;
- Reduced lead length – minimal lead lengths reduce parasitic inductance and capacitance, improving signal integrity;
- Fewer holes – eliminates the need for drilling many holes, simplifying PCB design, manufacturing and reducing material costs;
- Better heat dissipation – SMT components often exhibit better thermal characteristics due to their closer contact with the PCB.
Disadvantages of Surface Mount technology
Let’s now consider the disadvantages of Surface Mount Technology:
- Complex manufacturing – requires specialised, high-precision equipment, which can be expensive to set up;
- Difficult for prototyping – manual assembly and rework are challenging due to the small size of components;
- Limited component strength – weaker mechanical bonds compared to Through-Hole Technology (THT) makes SMT less suitable for high-stress environments;
- Thermal sensitivity – SMT components are more sensitive to heat, requiring careful control of soldering temperatures;
- Inspection challenges – the small size of components and dense layouts make inspection and testing more difficult;
- Rework complexity – repairing or replacing components on SMT boards is more difficult than on THT boards because they are placed so closely together;
- Vibration sensitivity – SMT is less reliable in high-vibration environments unless additional mechanical support is provided;
- Smaller pitch sizes – fine-pitch components (i.e. small spacing between the pins or leads of surface-mounted components) can lead to bridging (i.e. solder overflow) or shorts during soldering;
- High initial cost – the set-up for SMT manufacturing (machines, tools etc.) is more costly compared to THT for low-volume runs.
In cases where SMT does not appear to be the best available technique for your PCB assembly, it is a good idea to work with a CEM that is also capable of providing Through Hole Technology as an alternative service. Experienced CEMs will have highly skilled THT experts in-house, experienced in prototyping, smaller production runs, testing and repair work.
Key considerations before choosing SMT or THT for your assembly
Prior to selecting which technique to use to assemble your PCB assemblies, you’ll need to factor in the following to help balance the performance, cost and durability of your final product:
- Your PCB design – specifically component size and weight. Large, heavy components (e.g., transformers) are better suited for THT, while small, lightweight components are ideal for SMT;
- Mechanical strength – THT provides stronger mechanical bonds, making it better for high-stress applications;
- Assembly complexity – SMT supports compact, high-density designs, while THT is more suitable for simpler layouts;
- Manufacturing volume – SMT is more cost-effective and efficient for high-volume production, while THT is preferable for small runs or prototypes.
Top five reasons to use SMT
You should consider finding a CEM that can provide SMT services if your PCB assembly requires:
- Space optimisation – SMT allows for high-density component placement, making it ideal for compact designs and miniaturised devices;
- High-volume efficiency – automated SMT assembly is faster and more cost-effective for mass production, reducing labour and material costs;
- Complex design capability – SMT supports double-sided PCB assembly and fine-pitch components, enabling more complex and sophisticated circuit designs;
- Enhanced performance – shorter lead lengths reduce signal delays, making SMT better suited for high-frequency applications and faster signal processing;
- Weight reduction – SMT components are smaller and lighter, making them ideal for portable and lightweight electronic devices.
SMT for a strategic advantage
Generally speaking, the advantages of Surface Mount Technology provide product designers, engineers and purchasing managers with an operational advantage by reducing costs, improving manufacturability and enhancing the performance of PCB assemblies. Its ability to support high-density, high-volume and high-speed electronic applications makes SMT particularly well-suited for modern, complex designs. By leveraging SMT, you can achieve more efficient production processes and superior functionality in your electronic products, ultimately optimising both performance and cost-effectiveness.
Read our expert guide on Surface Mount Technology here to learn about the process in more detail.
MPE Electronics is an established and experienced contract electronics manufacturer specialising in PCB assemblies and full box build assembly for a wide range of commercial and industrial businesses.
To find out how MPE Electronics’ PCB manufacturing and assembly services can benefit your business, contact our expert and friendly team on +44 (0)1825 764822 or enquiries@mpe-electronics.co.uk.
