PCB Assembly

Through-Hole Assembly vs. SMT Assembly: Their Advantages and Disadvantages

Through Hole Assembly vs SMT Assembly

Recently, electronic devices have changed drastically since the demand for their components has risen. Coinciding is the change in standards and requirements for the components that are installed within electronic devices. As a result, the modern-day manufacturing of PCBs falls into two well-known methods: through-hole mounting and SMT assembly. Each one of these assembly methods has its own distinct set of advantages and disadvantages.

In this article, we’ll understand what through-hole and SMT assemblies are and explore their perks and caveats when manufacturing quality PCBs.

An Introduction to Through-hole Assembly

Before we delve into the advantages of SMT assembly and through-hole assembly, Let’s get ourselves oriented on each assembly method, starting with the through-hole method. Through-hole assembly, or mounting, is a process where electronic components are placed on a printed circuit board through a drilled hole, putting them in place and generally have a large size.

Through-hole-made circuit boards tend to be seen in most heavy-duty equipment that is used in harsh working environments.

What is SMT Assembly?

The next method of PCB assembly we’ll cover is SMT or surface mount technology assembly. This method involves the direct mounting of components on the surface of the circuit board, thus eliminating the need for boring holes to socket the said components resulting in smaller PCBs. Nowadays, most of the electronic hardware that our devices run is made using the SMT method of manufacturing boards.

Through Hole Assembly

The perks and caveats of through-hole assembly

Now that we are familiar with SMT assembly and through-hole assembly, the following sections will cover their respective advantages and disadvantages. We’ll start by covering the perks and caveats of utilizing the through-hole method of assembling printed circuit boards. Here they are, as listed.

Advantages of through-hole assembly

  • Components are less likely to fall off. Through-hole-assembled PCBs have more fixated components on the circuit board, making them less prone to go loose and fall off during the manufacturing process and transportation. This property makes THT-assembled PCBs better suited for clients that are based far away from the manufacturer’s factories.
  • It is best suited for high-power applications. Another perk that through-hole assembly-made PCBs have over their SMT counterparts is a higher resistance against exposure to high voltages. Since these PCBs are more resilient to strong electric currents, they are best suited for high-power environments such as industrial plants.
  • Resilient against harsh conditions. Through-hole-assembled PCBs are also resilient against different weather or environmental conditions. Compared to their SMT-made counterparts, they are less likely to deteriorate against the elements, making them an attractive option for aerospace, military, and aviation use.
  • Easy to repair and replace. If ever your through-hole-assembled PCBs get damaged at some point, do not panic, as they are the easier PCBs to fix or replace. Its design is made for easy identification of areas that have defective components or faulty wiring. Thus, if given to a specialist who can repair these PCBs, it is easier to restore them to working condition.
  • Cheaper in manufacturing costs. Since through-hole-assembled PCBs are simple in terms of design, they are cheaper compared to circuit boards done by SMT assembly.

Disadvantages of through-hole assembly

  • Lower component density and bulkier appearance. One notable caveat that through-hole-made circuit boards have is that they have lower component density and are larger in terms of size. Components tend to be spaced far away from each other, which contributes to their larger size, which some may find cumbersome to integrate into their devices or tools.
  • Boards are assembled manually. The second caveat that through-hole-made circuit boards have is that they are assembled manually, making them ill-suited for bulk production. In connection with this, there’s also a heightened risk of damaged components during assembly, which may lead to instances such as a broken lead during insertion.

SMT Assembly

Advantages and disadvantages of SMT assembly

SMT assembly-made PCBs are indeed a powerful tool, but they’re also not a size-fits-all solution for your devices. In this section, we’ll explore the strong and weak points of utilizing SMT-assembled printed circuit boards.

Pros of surface-mount technology PCBs

  • Compact in size. The first advantage that SMT-assembled printed circuit boards have over their THT-assembled counterparts is that they are more compact and thinner in terms of size. On average, SMT-made PCBs are around 60 to 80% smaller than through-hole circuit boards and also weigh a lot less. Therefore, these circuit boards will occupy less space during device integration, making them an ideal board for use in handheld devices.
  • Amplified signal integrity. Due to the density of components embedded in the circuit board, it possesses superior signal strength, making it ideal for high-input settings such as factory devices and the like. Since SMT components also don’t have leads, the chances of signal interference will be next to none.
  • Compatible with mass production. The process of creating SMT assembly PCBs can be automated, making them compatible with mass production. Just set up the picking machines and let them do their work on the incoming SMT-made printed circuit boards until they meet the quota that the client requested.
  • Lower material and manufacturing costs. In terms of material costs, an SMT-assembled printed circuit board is cheaper since the materials and components for them are cheaper to source as they are small electric components. Also, because of their small size, packaging and manufacturing costs are also lower.

Cons of surface-mount technology PCBs

  • Utilizes expensive tools and equipment. While SMT-assembled printed circuit boards have cheaper materials, the tools and equipment needed to manufacture them are very expensive. The tools range from picking machines to solder paste dispenses, which are a heavy investment for the manufacturer which cancels out the cheap cost of materials for these circuit boards.
  • Trickier and more expensive to inspect. The small size of the SMT-assembled boards will require more keen attention to detail to detect any defects early on. However, you can use inspection tools to find errors or issues, but that equipment comes with a hefty price tag.
  • Delicate durability. SMT assembly circuit boards, due to their small size and thinness, are delicate and easily damaged if they are dropped or exposed to high amounts of electricity. Therefore, these boards will require careful handling and tight static-proofed packaging to ensure they stay in good condition during delivery.
The Bottom Line between Through-Hole and SMT Assembly Boards

Both SMT assembly and through-hole-made printed circuit boards have their own merits and drawbacks which you can work around depending on the project you have. Working on huge electronic equipment? Use a through-hole assembly printed circuit board. Is your project involving the development of handheld gadgets? Use SMT-assembled circuit boards for that.

In short, identify what your project will use and what it needs so you can use either one of the two circuit types to its fullest.

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