Some Common Differences in Surface Mounting and Through Hole Technology

There are a number of key differences between surface mounting and through hole technology. Understanding these differences will make it easier for you to not only identify the right company to work on your project but also know which of the two processes is best.

Surface Mount Technology (SMT) versus Through Hole

SMT technology has become increasing popular over the past several years. In fact, it has now replaced the more conventional through hole technology for many applications. However, that does not mean that through hole drilling is obsolete since there are some situations in which this is the better technology.

For a long time, thru holes were commonly used to construct virtually all printed circuit boards (PCBs). With this technique, holes are drilled on PCBs through which leads of electrical components are inserted. These leads are then soldered to pads located on the opposite side of the board. Although this remains an extremely reliable method for securing leads to PCBs, the act of drilling additional holes makes this a more expensive method compared to SMT.

Something else to consider is the types of holes in an engineering drawing in relation to multilayer PCBs. In this case, the holes create certain limitations regarding a potential routing area for signal traces on the layers located under the top layer. With SMT, no holes are drilled. Instead, leads are mounted on the surface of a PCB.

Because the leads for SMT are smaller or completely nonexistent, surface mount devices (SMDs) are typically smaller than a drilled PCB. As a result, designing and developing smaller SMDs is possible. Considering that electronic devices are not only more compact but also complex, this makes SMT the better solution.


The following is a brief overview of the differences between through hole and surface mount technology:

  • SMT resolves space restrictions associated with through-hole mounting.
  • Any SMT leads are mounted directly to the PCB, whereas components with lead wires must pass through drilled holes.
  • SMT has a higher pin count than thru-hole technology.
  • SMT achieves more packing density due to the components being more compact.
  • SMT components are usually the more cost-efficient solution, although there is a greater initial investment for the required equipment.
  • Because SMDs are smaller, it is easier to acquire higher circuit speeds.

If you need professional SMT or through hole drilling services, you can rely on Star Engineering. We offer more than 70 years of experience in project engineering, production, installation, commissioning, and support. For a free consultation for your project, please contact us today.


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