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Through holes are considered to be one of the older designs by many, whereas surface mount is pretty new. And to some extent, it is undeniably true, but if we think about practical applications, the through-hole technology is still significantly better in specific scenarios. In the 1950s, printed circuit boards came with tracks written on only one side.

When you insert the leads of a component into the board, you increase the drilled holes. Therefore, the negative electrode side has an element soldered to the copper on the board. The later stages saw the introduction of tracks on both sides of the boards and inner layer tracks of the printed circuit board. It gave way to plated through-hole technology, making it possible to attach components to the inner layer of the circuit board, improving the concept of through-hole PCBA assembly.

Surface mount technology became known in the 1960s, and the applicability slowly rose in the 1980s. This technology was known as planar mounting in the beginning. The technique of surface mounting involved SMDs or surface mound packages. Components in this board have lead surrounding or underneath.

What separates surface mount from through-hole technology is that there is no need to drill holes in the circuit board to connect the tracks and the components. Establishing relationships through leads. The ingredients are in direct touch with the PADs of the circuit board And add solder paste to PAD with the help of stencil solder. There is also a pick and place machine responsible for placing the components on the solder paste set initially above the PAD. After setting these components, they have to be placed in a reflow oven or introduced in a vapor phase to be soldered permanently in the surface mount PCB assembly.

Higher Pin Count In SMT Assembly Than Through-Hole Technology

SMT beats THM in this regard because they can hold much higher pin count. Pin count on a component board is simply the lead count of the component, which is the total number of the part leads that a printed circuit board can fit.

The leads of through-hole components have become replaceable with the invention of smaller parts called vias. They allow conduction between the various levels of the PCB, and by doing so, eliminate the need for through-hole leads. On the other hand, surface mount components are much higher in performance, have shorter points, and the pins are much more interconnected, which leads to better speed.

SMT Assembly Components Are Usually Cheaper Than Through-Hole Components

The through-hole method requires drilling holes in the empty side of the board. It is a task that takes a lot of time and costs a hefty amount. THM also makes the routing area limited in any board that has multiple layers. It is only because the holes should pass through all these layers. When we look at the through-hole PCBA, the assembly side comes at a fraction of a cost for placing components than a surface mount.

Advantages And Disadvantages Of Through Holes And SMT Assembly



The leads must be inserted through the drilling holes. It makes the component sturdier. They can handle a lot of stress from the environment, mechanics, heat, and pressure.

PCBs of THM is also suited for collisions or extreme accelerations, so it is ideal for advanced applications like military or aerial equipment or transformers.

THM can be easily replaced, so the prototype is mainly for testing applications.


The bigger component size and one-sided availability make the manufacturing cost higher.

The components of THM are also placed and soldered manually, leaving little room for automation like SMT, so it is expensive.

Boards with THM components must also be drilled, so there are no tiny PCBs that come at low cost if you are using THM technology.

SMT Assembly-Surface mount technology:


SMT has the fewest components, and we can place them quickly. Components can be mounted on both sides for automated welding. All these make it much cheaper.

Small, lightweight PCBs predominantly use the SMT because they are much smaller than the THM boards and weigh less. The components are packed tight on the board, so with many electronics focusing on reducing the size, this is a distinct advantage.

The SMT components are smaller and can be placed much faster when the assembly is happening, so the overall production cost is low.

On the other hand, the surface mount assembly has a plurality of terminals soldered to the tubular body. Compared with flat chip vias used, the cost of these components is much cheaper.

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