ANR Manufacturing Ltd

Unit 1, Jacksons Industrial Estate
Wessex Road Bourne End
Buckinghamshire SL8 5DT
+44 (0)1628 819157 Call ANR Manufacturing Ltd Email ANR Manufacturing Ltd

Sub contract PCB assembly

Types of PCB Assembly Processes

PCB assembly is the process of assembling and soldering electrical components on a circuit board. The system is used for a wide range of electrical items that vary from TV remote controls to aircraft radar systems, and a million things in between. With such a huge variation in PCB requirements, it is no surprise that there are different many different types of PCB assembly processes. Here are some of the main ones:

Basic PCB assembly
  • Solder paste application: The paste is applied to areas where solder is required. It is made up of small grains of solder mixed with flux.
  • Component placement: The components are placed into the correct positions.
  • Reflow: The circuit board is passed through a reflow oven that heats it so that the solder and flux melt together. The board is then cooled so that the solder can solidify and fix the PCB components in place.
  • Inspection: this is performed to check the functionality of the components. This stage helps to identify any positional and connection issues.
  • Through-hole component insertion: This takes place as many circuit boards require through-hole and surface mount components.
  • Final inspection and test: A final test takes place to make sure it is fully functional and can work to its required electronic capacity. 

Through-hole PCB assembly

This process is one of two ways of mounting components onto a PCB. The leads run through the board and are soldered to pads on the opposite side. Only a few steps differ to the traditional method and these are:

  • Components placement: The components are placed manually onto the board by highly skilled engineers, rather than through the use of a machine.
  • Inspection and component rectification: If any faults are found with the components, then they are dealt with at this point only, before any soldering takes place.
  • Wave soldering: In wave soldering, the component mounted PCB board moves over liquid solder, heated at the temperature of over 200°C, in a slow wave motion. It is then left to cool so it can solidify.

Surface mount PCB assembly

With this method, electrical components are mounted directly onto the surface of a printed circuit board. There are also some different steps involved:

  • Solder paste application/printing: Solder paste is applied on the board using a solder paste printer.
  • Components placement: The placement of components is done automatically rather than manually.
  • Reflow soldering: The solder paste melts and settles around the placed components. It then cools and solidifies.


  1. What are the key differences between through-hole and surface mount PCB assembly? Through-hole PCB assembly involves manual placement of components onto the board by skilled engineers, whereas surface mount assembly utilises automated component placement.
  2. How does solder paste application differ in basic PCB assembly versus surface mount PCB assembly? In basic PCB assembly, solder paste application involves applying the paste to specific areas where solder is required, typically done manually. In contrast, surface mount PCB assembly uses a solder paste printer for precise application of solder paste on the entire board before component placement.
  3. What quality control measures are implemented during the PCB assembly process? Quality control in PCB assembly includes inspection stages to ensure proper functionality and identify any positional or connection issues. Skilled engineers meticulously inspect components before soldering, and final inspection and testing procedures are conducted to verify the board's full functionality. 

Here at ANR Manufacturing LTD we are able to undertake sub contract PCB assembly projects and offer a wide range of PCB assembly services. We will make sure your requirements are met on time and within budget. For any information on what we do, then please do not hesitate to get in touch