A PCB (Printed circuit board) controls the electrical signals that originate from outside sources to the components mounted on the board. The electrical components present in the board maintain and contribute to the functions of the electronic devices. The board and its composition are also vital in making the PCB work according to its functions. Without the PCB, the electronic devices are useless.
A PCB can either be one layered or multi-layered, depending on the type and functions of the electronic device. A simple device such as cell phone charger has single and small-sized PCB. On the other hand, a complex device such as a computer-controlled printer can contain up to 12 layers of PCBs or maybe more.
An electronic device PCB passes through two main stages, the PCB fabrication, and PCB assembly. The fabrication stage is the production of the board and the printing of the circuitry while the assembly stage is the mounting of the components. After finishing these stages, we test the PCBs before we send them to the packaging and delivery department.
In the assembly stage, we use surface mount technology (SMT) or through-hole technology (THT).
As technology advances, more and more electronics companies develop complex devices that require smaller and sophisticated PCBs. These PCBs can perform more than one, as well as simultaneous, functions. To cope up with the rising demand for these kinds of PCBs, circuit board manufacturers make some improvement with the existing production of PCB.
Thus, the surface mount assembly started where manufacturers can use both sides of the board to place electronic components. Nowadays, multi-layering of PCBs is possible without making the electronic devices look bulky. This versatility of the SMT becomes so popular in the telecommunications and IT industry where fast computing requires more PCBs in one computer device. This technology allows higher component compactness, where we can place multiple integrated circuits and more capacitors and resistors without sacrificing electrical functionality.
Why do we use SMT?
Besides, SMT allows us to cater to clients who are budget conscious. One, this technology makes use of both sides of the board. Thus, it contributes to the lowering of the total cost of the assembly. Second, we do not need to pre-drill the board for mounting the electrical components. As results, PCBs are thinner. This requirement reduces the cost of manufacturing the board.
Third, since PCB assembly is a surface mounting method, we use electrical components with shorter pins. This eliminates the need to cut excess pins. Sometimes, cutting the excess pins may contribute to the loosening of the soldered pins on the board, which is a minor problem in through-the-hole technology. Fourth, in SMT, we can still use manual assembly or the conventional assembly to mount smaller components on the board.
However, despite the versatility and cost-effectiveness of the SMT, a few minor drawbacks are present. One disadvantage is the quality of the soldered components. Although we use the highest quality of soldering materials, we know that the binding of the components to the surface of the board is less dependable than the THT. Thus, we never recommend the use of SMT on devices that are for heavy-duty use like drilling equipment.
Second, we never use SMT on prototypes. A prototype is a sample device for mass-produced devices, especially for electronic devices that are offered to the market for the first time. SMT settings are harder to change. Changing a single setting on an SMT machine may take weeks to perfect, which is not time efficient. Thus, we use the THT to create a prototype.
In THT, we drill holes on the printed board. We still use this method on PCB assembly that requires stronger binding between the electrical components and the board. Examples of assembly requiring THT are the production of prototypes, military equipment, and other electronic devices that are exposed to extreme weather conditions. One disadvantage is the cost of making the board. THT assembly requires thicker board due to the drilling of holes.
Although SMT is more popular than THT in PCB assembly, the traditional through-hole technology remains to thrive. Manufacturers still use this technology and we are one of them because THT is still required on heavy-duty electronic devices. Surface mount technology, on the other hand, is highly recommended on complex devices that require multi-layered PCBs.