Surface mount technology (SMT) and through-hole insert technology (THT) are the two main methods for mounting electronic components on printed circuit boards (PCBS). While they all play an important role in electronics manufacturing, there are signi...
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Surface mount technology (SMT) and through-hole insert technology (THT) are the two main methods for mounting electronic components on printed circuit boards (PCBS). While they all play an important role in electronics manufacturing, there are significant differences in technology and application.
Surface mount technology (SMT) : In a narrow sense, SMT is to paste surface components onto the PCB, and realize the interconnection of electronic components through integral heating. However, in a broad sense, it includes many aspects, such as chip components, surface assembly circuit boards and their process design, surface assembly equipment (such as printing presses, dispensing machines, reflow welding equipment) and assembly materials (such as solder paste, flux).
Through hole insertion technology (THT) : A traditional installation technology that uses THC (perforated mounting components) and THD (perforated mounting devices) to complete the installation and welding on the PCB by hand welding, dip welding and wave soldering. Through hole insertion technology requires more space on the PCB design because the components need to penetrate the board face, which limits the compactness of the design.
The fundamental difference between SMT and THT is "paste" and "insert". Surface mount technology (SMT) uses leadless or short-lead components to mount components on the PCB pad surface; The through hole insertion technology (THT) relies on the metalized hole on the printed circuit board to fix the position, and inserts the long pin component into the PCB pad hole and performs soft soldering.
SMT process in advance to apply solder (solder paste) on the pad, mount the components after heating to complete the welding process, components and solder joints on the same side of the PCB; The THT process uses the molten solder flow through the wave welding machine to achieve temperature rise and welding, and the components and solder joints are respectively on both sides of the PCB.
Table 1. SMT and THT process comparison
Advantages of SMT process
1. High assembly density. The area and mass of chip components are greatly reduced than that of traditional perforated components, and the more compact layout improves the integration of components.
2. High reliability. Chip components are small and light, so the seismic ability is strong; Automatic production, high reliability of mounting and welding, low rate of bad solder joints.
3. Good high-frequency characteristics. The leadless device reduces the influence of parasitic inductance and capacitance, and improves the high frequency characteristic of the circuit.
4. Simplify the process. SMT technology simplifies the production process of electronic machine products, reduces the production cost and improves the production efficiency.
In practical applications, SMT and THT technologies are sometimes used simultaneously to meet the needs of different component and board designs. For example, THT technology may be selected for large components or parts with high reliability requirements, while SMT technology may be selected for small components and parts with high density integration. This hybrid approach can leverage the advantages of both technologies to enable more flexible and efficient electronics manufacturing.
