THT vs SMT

Surface mount technology (SMT) and traditional through-hole technology (THT) are the two main component
assembly processes in electronic product assembly.

There are many differences between the two in terms of components, substrates, assembly processes, etc.,
which lead to different performance and application characteristics.

SMT vs THT –Fundamental Difference

The fundamental difference between surface mount technology and through-hole technology is the
components assembly way.

SMT is to mount components directly on the surface of the PCB that uses a pick and place machine, while
THT is to insert leaded components into through holes on the PCB.

SMT process characteristics

The components are small and lightweight, which reduces PCB space and weight.

High assembly density can realize electronic products with higher integration.

It has high production efficiency and can realize automated high-volume PCB assembly.

THT process features

Components are large and heavy, requiring more PCB space and weight.

It has low assembly density and is hard to realize highly integrated electronic products.

The production efficiency is low and requires more manual operations.

THT vs SMT –specific differences

There are specific differences between SMT and THT in the following aspects:

Substrate:

The PCB used in the Surface mount technology process needs to reserve pads, while the PCB used in the
THT process needs to reserve through holes.

Components:

The components used in the SMT process are sheet components, while the parts used in the THT process are
lead.

Component form:

The components and solder joints of the Surface mount technology process are located on the same plane,
while the components and solder joints of the THT process are located on both sides of the board.

Solder joint shape:

The solder joints of the SMT are round or oval, while the solder joints of the through-hole technology
are rectangular or diamond.

Assembly process method:

The Surface mount technology process uses a placement machine and an SMT reflow oven, while the
through-hole technology process uses a plug-in machine and a wave soldering oven.

Performance and application characteristics of SMT and THT

There are differences between the SMT and THT process's performance and application characteristics.

1)Performance advantages of the SMT process

The performance advantages of surface mount technology are mainly in the following aspects:

Small and lightweight: The components used in the SMT are small and lightweight, which can effectively
save PCB space and weight.

It is significant for electronic products that pursue lightness, thinness, and portability.

High assembly density: SMT technology can achieve higher component assembly density, thus realizing more
highly integrated electronic products.

It is significant for electronic products that pursue high performance and functionality.

High production efficiency: SMT process can realize automated mass production, thereby improving
production efficiency and reducing costs.

2)Application characteristics of the SMT process

The SMT process has the advantages of high integration and high production efficiency, so it has been
used widely in consumer electronics, communication equipment, and other fields.

For example, almost all electronic products, such as smartphones, tablet computers, and laptops, use SMT
technology.

3)Performance advantages of the THT process

The performance advantages of the THT process are mainly in the following aspects:

High mechanical strength: The components and solder joints of the through-hole technology process are
located on both sides of the PCB, which has good mechanical strength.

High reliability: The solder joints of the THT process use molten solder, which has high reliability.

It is significant for electronic products that need to work in harsh environments.

4)Application characteristics of the THT process

The THT process has good mechanical strength and reliability, So there is still demand in automotive
electronics and the military. For example, parts need to endure vibration and impact in-car electronics.
They use the through-hole technology process.

The future development of SMT and THT

With the continuous development of electronic products, Surface mount technology will be more widely
used in the future.

As technology advances, the cost of the SMT process will be reduced, making it more competitive.

The THT process will still have certain applications in some specific fields, but its application scope
will gradually narrow.