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Through-Hole Mounting for Printed Circuit Boards: Is it Still Worth It?

Most electronic devices are now manufactured through SMT. Surface-mount technology, or SMT, is the latest technology used for mass-producing mobile phones and computer equipment. Among hobbyists and small business owners, however, THM is still popularly used. Through-hole mounting, or THM, is an old technology, but is still used for prototyping and small-sized electronics businesses. They are both used to manufacture printed circuit boards.

In this article, the traditional THM will be questioned of its worth in manufacturing printed circuit boards. It will also discuss why many electronics enthusiasts do not leave this old technology for the newer SMT.

Pcb

As stated, through-hole mounting is already an old, but standardized technology. It basically means that printed circuit boards are drilled through, thereby making a hole. An electronics component’s pin is then inserted into that hole. An electronics component is therefore mounted, or placed permanently, onto the circuit board.

THM was the original technology used for the mass production of PCBs, but was completely replaced by the automation-friendly SMT. Through-hole, however, still has many followers. It may not be used anymore in the big electronics manufacturing industry, but it is still popular with small businesses and electronics hobbyists. This technology is commonly used in prototyping circuits. To use this technology, a simpler tool (like a soldering iron) is required.

As expected, this old technology does have many disadvantages. This technology relies on the drilled holes for mounting and support. These holes are time-consuming. More time means additional manufacturing costs. The board designers must also be aware of the effect of drilling holes to double-sided printed circuit boards. Inappropriately drilled holes may cause a short circuit that can damage the electronics product, as a whole.

THM, as stated, is not assembly-line friendly. This technology was used when automated assembly lines were still very expensive to acquire. Component placement in THM is slow and tedious. Placing components with SMT, on the other hand, are quick and easy.

Furthermore, THM uses skill-extensive and non-repeatable soldering techniques to create perfect electronics products. Repeatable, in this respect, requires a worker to repeat every task with exactly the same result. SMT, on the other hand, uses reliable and repeatable reflow oven baking techniques to mount the components.

On the bright side, THM still follows the standards in manufacturing. Majority of passive components which are used today are still of THM type. Breadboards and universal protoboards also follow the THM standard guidelines. It is better, therefore, to use this technology while still on the research and development phase.

This technology is also tester-friendly. Standard electronics components are big, and so are the gaps between their pins. It is easy to reposition various testing tools around a PCB, because of the size of the test components. SMT components, on the other hand, are so small that it is difficult to attach even a single test probe around an under-test pin.

THM components are also more resistant to electrical and thermal damages. These components have higher voltage tolerance. They can withstand voltages of more than five volts. They can also withstand heat from an ordinary soldering iron. SMTs, on the other hand, are designed specifically for small electronics packaging. They may already be damaged if electrostatic discharge, voltages of greater than 5V, or the heat of a 30w soldering iron are applied to one of the component’s pins.

In as far as the solder is concerned, THM has stronger mechanical bonds. The amount of solder can vary between the weights of different electronic components. A heavier component can therefore be supported more with thicker deposits of soldering lead. SMH, on the other hand, just allocate enough solder to a joint.

Through-hole mounting may not be suitable for modern assembly lines. This old technology is now used for secondary and customized assembly of printed circuit boards. It is not a part of a primary and large-scale assembly process. It will still be relevant in the future, though. Electrical, thermal and mechanical devices still require THM. Unless future SMT devices, or SMDs, are developed to withstand those conditions, THM will still be needed.

Breadboards and universal protoboards also follow the THM standard guidelines. It is better, therefore, to use this technology while still on the research and development phase.

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