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What is through-hole PCB assembly?

Through hole technology (THT) and surface mount technology (SMT). So far, these two types of PCB assembly are very common in the electronics manufacturing industry. The printed circuit board assembly (PCBA) can realize the close connection between the bare PCB and the Electronic Components, so as to fully realize the corresponding electrical functions, and finally play its own role for the reliability of electronic products. They have been widely used in PCBA process and have their own advantages or technical fields.

Through-Hole Assembly
• Definition of Through-Hole Assembly
Through-Hole Assembly refers to the process of soldering through-hole components to the bare board by wave soldering or manual soldering in the PCBA Manufacturing process. The component leads pass through the holes of the PCB board.
• Application of through-hole components
Through-hole components (THC) are suitable for high-reliability product layers that require stronger bonding because they can withstand higher environmental pressures, and the wires pass through the board holes. This is the wide application of THT that may suffer from military and aerospace The main cause of the product is from extreme acceleration, collision or high temperature. In addition, through-hole technology is also popular for testing and prototyping, sometimes requiring manual adjustment and replacement.
•Through Hole Components
There are two types of through-hole components: axial lead components and radial lead components. The axial lead component contains a straight line whose terminal passes through the component. In the THA process, the two ends of the lead pass through a hole on the circuit board, making the component closer to the circuit board and flatter. The figure below shows a typical axial lead component.
However, the radial lead element includes leads protruding from the element body. The figure below shows a typical radial lead assembly.
According to the figure above, it is easy to understand the difference between the axial lead element and the radial lead element. The former represents a flexible distance between two leads, while the latter represents a fixed distance. In addition, compared with the axial lead elements, the radial lead elements will be located above the circuit board, resulting in a smaller footprint on the board.
• Advantages and disadvantages of through-hole components
Through-hole installation shows stronger mechanical bonding and is suitable for products that are prepared to withstand mechanical stress. In addition, the through-hole assembly is easy to manually adjust and replace, and it has been widely recognized through testing and prototyping.
Because the through-hole component leads through the holes on the board is very time-consuming and leads to higher costs. Through-hole mounting also limits the wiring space of a multilayer PCB, because the drill holes must cover all layers of the circuit board.
When it comes to through-hole mounting, wave soldering or manual soldering, reliability and repeatability will all be challenged by reduced manufacturing efficiency.
Overall comparison of through-hole components and surface mount components
According to the introduction listed above, it can be concluded that surface mount components are more effective and cost-effective than through-hole assembly. Modern electronic products have witnessed the application of SMT in most electronic products. When special mechanical, electrical, and thermal properties are first considered, through-hole mounting is still important.
Although science and technology are constantly making progress at all times, new products will surely replace the old ones, which does not mean that traditional technologies must be completely eliminated. For example, multi-layer PCBs are more advanced and complex than single-layer PCBs, but do you want to use multi-layer PCBs in clocks or simple toys? The answer is absolutely no.