SMT vs Through Hole：Which PCB Assembly is Most Cost-Effective？

Performance and cost in the realm of electronics production depend on choosing the correct assembly method. Of the several approaches accessible, Surface Mount Technology (SMT) and Through-Hole Technology (THT) are the two most often used ones for PCB assembly. These two assemblies can be combined to create some products or used as individual technologies. Though seemingly little, this variance affects several aspects including board design, materials and techniques employed, heat dissipation, and related labor and setup expenses.

⦁ Complete SMD: The PCB can have the components attached on one side or both sides.

⦁ MIXED: It's frequently utilized when some components aren't SMD accessible. With so many process stages, this assembly type is the most complicated one to produce. SMDs and through-hole components are combined here.

⦁ Fully TH: Prototyping or testing significantly rely on this. In this the components either on both sides (double-sided) or one side (single-sided) of the PCB.

Both have certain benefits and are applied in various situations. This article offers a thorough comparison of SMT and Through Hole so that procurement experts and design engineers could decide with knowledge. Economically, nevertheless the decision will rely on various technological and financial considerations.

1.    Standard Soldering Technologies:

Surface Mount Technology (SMT): Surface Mount Devices (SMDs) typically have smaller footprints, allowing for smaller designs and high-density layouts. Using automated pick-and-place devices, components are put directly onto the surface of the printed circuit board.

Through-Hole Technology (THT): The leads of the components are soldered into place after being put into pre-drilled holes in the printed circuit board (PCB) using through-hole technology (THT). On the flip side either we can do wave soldering or manual handling. Commonly used for mechanically stressed components, large capacitors, or connections.

2.    SMT PCB Assembly:

Direct component mounting onto printed circuit boards is accomplished by surface mount technology (SMT) PCB assembly, which is employed in batch solder reflow. Solder paste is put to the PCB to begin the procedure. Careful placement of the components on the board will be done in a safe manner. The next step is to carefully heat the assembly in a reflow oven. A connection is formed between the PCB and the components when the solder paste melts, also known as "reflow," beneath the heat. After cooling, the solder cures, creating a solid bond between the PCB and the components. SMT assembly makes extensive use of robotics. This might result in significant labor cost savings for large manufacturing runs.

Small metal or ceramic contacts on their bottom allow them to be connected straight into pads on the PCB rather than wire leads. Lighter components and high density assembly are guaranteed by this special packaging. SMDs have unique packaging unlike that of conventional components.

3.    Through-Hole Assembly:

THT assembly begins with exact hole drilling into the PCB. These holes fit the requirements for the components to be fastened. These holes are filled with leads from the THT components thus ready for the soldering operation. Two techniques of soldering are selective soldering and wave soldering.

A solid electrical and physical connection between the lead and the PCB assembly can be achieved by filling the hole with hot solder. A molten pool of solder is passed across the PCBA during wave soldering. A "wave" of solder is created by a pump and adheres to the printed circuit board assembly (PCBA), securing the components. Conversely, PCVA locations that require soldering are specifically targeted by selective soldering. This method eliminates the need for solder masks by precisely dropping solder on the board where it is required.

4.    Comparing SMT and Through Hole Assembly Costs

1) Material and Component Costs

Because of their standardized containers and broad availability, SMT components—which are usually smaller and less expensive to manufacture in great numbers—are Their less weight lowers shipping costs and resource use. Conversely, especially when manufacturers move manufacturing toward SMT for mainstream electronics, THT components often be bigger, heavier, and more costly.

2) PCB Manufacturing Costs

Particularly for multilayer boards the through-hole assembly calls for drilling holes in the PCB. Which adds an additional fabrication process step and raises manufacturing costs. Because they need less plated-through holes therefore lowering manufacturing complexity and material utilization is there. SMT PCBs are simpler and less expensive to construct.

3) Equipment and Setup Costs

Establishing an SMT assembly line calls for large upfront equipment purchases including automated placement systems and reflow furnaces. But since reduced per-unit assembly costs allow this arrangement to become more affordable over time for big manufacturing runs. Although through-hole assembly initially has less setup costs, human labor and lengthier manufacturing cycles cause it to become more costly on scale.

4) Testing and Quality Control

With the use of automated inspection systems like AOI and SPI. SMT processes assist in fault detection rates and rework cost reduction. Conversely, for more complicated assemblies through-hole assembly often calls for human inspection that raises both time and personnel expenses in quality control.

5) Repair and Rework Costs

Because of their greater size, through-hole components are usually easier to replace during rework; yet, rework SMT boards calls for specific tools and qualified experts, hence raising repair costs. Higher assembly precision in automated SMT lines, however, sometimes results in a lesser demand for rework.

Conclusion

Because of automation, reduced component sizes, and lower per-unit costs at volume, SMT is obviously the more cost-effective assembly technique for most modern electronic products especially in consumer electronics, telecommunications and computers. Still, through-hole assembly is important in specialized uses where mechanical strength, durability, or particular component availability take front stage. SMT is the recommended solution for small and high-density designs, usually where mass production is taken into account.

Through-hole may offer the greatest value for goods but depends on conditions like limited batch runs and high labour. Production volume, application type, and functional requirements ultimately define the most affordable strategy.

To support these diverse needs, JLCPCB offers both SMT and through-hole assembly services with professional quality, fast turnaround, and competitive pricing. Whether you’re prototyping or moving into large-scale production, you can rely on JLCPCB to bring your designs to life