The processes of PCB and SMT assembly

by Thomas

A PCB, known in full as a Printed Circuit Board, is a board that applies conductive traces and other elements etched into a copper foil. The role of the board is to connect electronic devices electronically. They also help give the machines the ability to function swiftly by allowing for easy movement of electricity. The best PCB companies offer PCB assembly and SMT assembly services. This post seeks to expound on PCB assembly and SMT assembly.

What is PCB assembly?

PCB assembly is the process of manufacturing a PCB board with components mounted on it. PCB assembly is a lengthy process. It involves several manual and automated steps that must be executed with utmost care and attention to detail. The slightest errors in the process can result in numerous issues and failures of the final project or assembly.

The process of PCB assembly

The process features the following steps;

  • Application of the solder paste
  • Placing the components (this process is entirely automated using robotic and place machines)
  • Solidification of the solder paste to the correct specifications
  • Reflow soldering; where the solder paste is melted, and the assembly is moved in the conveyor belt then exposed to a series of heaters for cooling
  • Inspection of the PCB to ensure its functionality (the role of this step is to identify faulty connections, component misplacements, and other issues)
  • Through-hole component insertion
  • Final inspection
  • Cleaning

What is SMT assembly?

SMT assembly, also known as surface mounting, is a method for producing electronic circuits by placing components directly on the surface of a board. This technique was established in the late 1970s and the early 1980s. Its establishment was a result of the continued growth of the electronics manufacturing industry.

The SMT assembly process

  • Determining the positioning of the components and how the PCB is meant to function
  • Application of the soldering paste for holding the components together
  • Solder paste inspection (the process is automated mainly)
  • Automatically selecting, reviewing, and placing the components
  • Reflow soldering for connecting the components
  • Testing the PCB to ensure that the assembly process was successful

What is the relationship between PCB assembly and SMT assembly?

SMT assembly is an alternative to PCB manufacturing. Both PCB assembly and SMT assembly are methods efficient and modern methods of assembling electronics. The two methods are highly similar. Another similarity between these two terms is that they both involve the application of circuit boards. Both PCB and SMT are types of circuit boards. The components involved in SMT assembly are also similar to those involved in PCB assembly. In simpler terms, PCB assembly is a processing service based on SMT.


PCB assembly can be defined as the circuit board plug-in assembly process, also known as SMT. The two processes have a lot of similarities and quite a few differences. The primary difference is that PCB is a popular processing technology that involves buying back the PCB substrate and mounting it to the PCB via a specific technology. It helps increase the processes of procuring components.

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