Over the years, developments in the fabrication of printed circuit boards or PCB assembly have been made. At present, it has become an integral component of various electronic devices, machines, gadgets, automobiles, and many electrical appliances. Without high quality PCB’s, having upgraded smart phones and laptops would not be possible. It is used in a wide array of industries that it has developed various PCB fabrication techniques over time.
Two of the most widely-used PCB assembly techniques are going to be the focus of this article: the plated through-hole construction or PTH and surface mount technology or SMT. Though there were other techniques used before them like the box-build construction and point-to-point assembly, these two are the most popularly used in PCB construction today. Hopefully, this article would be able to help you understand the differences and advantages of each technique.
Plated though-hole construction (PTH)
The development of plated through-hole construction technique started in 1949 when Moe Abramson and Stanislaus F. Danko of the US Army Signal Corps discovered the Auto-Sembly process. This process makes use of a copper foil interconnection pattern wherein component wire leads are inserted into it and are soldered. The US army obtained the patent for their work in 1956.
It continued to evolve as various etching techniques and board lamination methods were developed.
In PTH construction, the electronic components are mounted into the PCB by inserting the wire leads into drilled holes and soldering it into the copper patterns on the other side of the circuit board. Soldering of the leads can be done manually, but for large scale fabrication of PCB’s, using a wave soldering machine is more efficient.
Circuit boards made using this method is known for its durability. Since leads are soldered on one side of the board, it forms stronger bonds. However, the process of drilling holes into the PCB must be done accurately and this makes the PCB fabrication process more expensive.
Surface mount technology (SMT)
SMT or surface mount technology is the most developed and widely used Pcb assembly technique used today. It appeared during 1960’s but it gained attention and was used in early 1980’s. SMT was then widely known by 1990’s and continued to evolve up to our present time.
In this type of PCB fabrication technique, electronic components are mounted to the surface of the circuit board, hence it is named surface mount technology. The components were redesigned too; instead of having wire leads that used to be inserted into holes (like in PTH assembly), it has end caps or small metal tabs which are directly soldered on the surface of the circuit board. And with the modern world’s continuous development of smaller and slimmer devices, SMT became more in demand, as it allows electronic components to be placed on both sides of a circuit board. Even smaller PCB assemblies now have much higher circuit densities, resulting to faster upgrading of electronic devices.
Surface mount technology has also been found to have more advantages than plated though-hole construction. Using this process is more time efficient and less expensive as it does not require lots of drilling of holes and is also highly automated. It is also ideal for industries that require compact designs as PCB’s made using SMT are smaller.
In conclusion, surface mount technology is better than plated through-hole construction. Though each has remarkable advantages, manufacturers benefit more in using SMT. However, there are also instances where the use of both assembly techniques is needed. The result of these combined PCB assembly technique is really great, as the product produced could be slim and handy, yet durable.