2021 Best SMT Guide for Beginners: Basic Concepts

SMT stands for Surface-mount technology. It is a method of mounting electrical components directly on a printed circuit board’s surface (PCB). A surface-mount device is an electrical component that is installed in this manner.


SMT has essentially supplanted the through-hole technology construction method of fitting components in the industry, owing to its enhanced manufacturing automation lowers costs and increases quality. It also makes it possible to fit more components into a given area of the substrate. You can manufacture 2-4 layer PCB at JLCPCB for as low as $2 and even get free SMT assembly by acquiring coupons.

Additionally, if you are a newcomer to JLCPCB you can get one time $18 registration coupon which can be spent to test manufacturing capabilities and even get assembled PCB nearly for free.

How is SMT different from THT?

Both technologies are under-utilization on the same board. Although, THT being employed for big transformers and heatsinked power semiconductors. SMT components have smaller or no leads. They are frequently smaller than their through-hole counterparts.

PCB drilling

In today’s electronics manufacturing, surface mount technology is the most often underutilization method for PCB assembly. Anyone can fabricate SMT components exceedingly small and many types, particularly SMT capacitors and SMT resistors.

What is the SMT process?

Surface-mount technology (SMT) refers to the assembly of electronic components using automated machines that install components on the surface of a board (printed circuit board, PCB). When it comes to electronic assembly, SMT is the industry’s most popular method.

pick and place smt machines at JLCPCB

You can put SMD components on both the top and bottom sides of a PCB using surface-mounted technology. So, drilling holes in the printed circuit board is unnecessary.

What is the difference between SMD and SMT?

An SMD refers to an electronic component that is mounted on a PCB. SMT refers to an electronic component that is mounted on a circuit board. SMT (surface mount technology), on the other hand, refers to the method of placing electronic components on a printed circuit board.

PCB soldering

Surface-mount technology (SMT) is a method of mounting electrical components directly on a printed circuit board’s surface (PCB). A surface-mount device is an electrical component that we can install in this manner (SMD).

THT’s soldering procedure frequently results in less dependable solder spots than SMT solder. Furthermore, the THT assembly process is more time-consuming and thus more expensive than SMT.

What is the SMT code?

Standard tolerance resistors are usually coded using a three-figure SMT resistor coding method. This SMD resistor labeling system employs three figures, as the name implies. The significant figures are indicated by the first two figures in the code, and the third is a multiplier.

What are the SMT Repair Equipment Options?

SMT Repairing Equipment Electronic PCBs and machines to remove and replace electronic components, assembly tools, and equipment use conductive tips or a hot air blower. Other conductive tips with built-in heating components are available at a somewhat higher price.

What is the role of an SMT engineer? 

A process engineer for surface mount technology (SMT) works on the production line of surface mount technologies, which involves connecting electronic materials to printed circuit boards. An engineer will check the finished products to determine their quality.

When and why did SMT become well-known?

Surface mount technology gained popularity in the 1980s. SMT devices were immediately discovered to be far more efficient to manufacture than conventional PCB manufacturers such as JLCPCB. SMT allows for highly automated production. That’s why it has become famous among manufacturers as well as users.

How can SMT manufacturing quality be better?

PCB testing

In terms of SMT assembly, solder paste plays a key role in assembly manufacturing. After all, 70% of quality defects in electronic products with SMT assembly applied result from low-quality solder paste printing. Thus, improving solder paste printing performance is an important measure to increase SMT assembly manufacturing quality.

What are the main advantages of SMT?

The following are the key benefits of SMT over the traditional through-hole method:

  • Smaller components.
  • A higher component density and a greater number of connections per component.
  • You can attach components to the circuit board from both sides.
  • Greater connection density because holes do not obstruct routing space on inner layers or back-side layers.
  • Due to the surface tension of molten solder that pushes components into alignment with the solder pads. That’s why small faults in component placement come automatically under addressing.
  • Lower resistance and inductance at the connection. As a result, fewer unwanted RF signal effects and better and more predictable high-frequency performance.
  • Improved EMC performance due to a smaller radiation loop area and lower lead inductance.
  • Drilling fewer holes is the requirement.
  • Using automated equipment lowers the initial cost and time of setting up for mass production.
  • Automated assembly is easier and faster.
  • Many SMT parts are less expensive than through-hole equivalents.

What are the disadvantages of STM?

Here is a list of some disadvantages of the STM.

  • SMT may not be appropriate as the only attachment technique for components susceptible to regular mechanical stress.
  • Solder connections on SMDs may prove harmful by the temperature cycling of potting compounds.
  • Many types of SMT component packages are not suitable to install in sockets. 
  • SMDs are not usable directly with plug-in breadboards.
  • The diameters of solder joints in SMT are shrinking dramatically as ultra-fine pitch technology improves.
  • As the amount of solder available for each union decreases, the reliability of solder joints becomes more of a worry.
  • Voiding is a typical solder joint problem, particularly when reflowing the solder paste in an SMT application.
  • Because SMDs are typically smaller and have less surface area for marking, the repair is difficult.

Where to hire best SMT PCB Assembly?

The JLCPCB PCB SMT assembly outsourcing and electronics end up being something quite advantageous and economical. There is no need to make large investments in specialized machinery, qualified professionals, and excellent raw materials.

JLCPCB is a specialized company that offers outsourced assembly of boards and electronic products. Should invest in modern technologies, as the market is quite demanding.

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