The PCB Assembly Process


The printed circuit board, or PCB, assembly process is not a part of the manufacturing process, as the components, including the board with the required layers, traces, and other critical elements, are created first. Instead, it is the step where all necessary components are brought together to create a PCB that works as intended.

Assembling a PCB requires the right components, a well-designed board, and the technology necessary to assemble it correctly. For instance, a variety of advanced technologies are used, including Surface Mount Technology or SMT Assembly, Through Hole PCB Assembly, and Hybrid Thick Film Assembly.

While some applications may use only one of these technologies, many boards require a combination. Regardless of the type of technology used, the PCB assembly process involves a few basic steps.

A Basic Review of The PCB Assembly Process

Solder Paste

Typically, the first step in creating a PCB is to apply solder paste, a type of solder used with infrared reflow machines during the PCB assembly process. The sticky solder paste can be applied to the board by jet printing, stencil printing, or syringe, and temporarily holds components in place. Once the components are in place, the board is heated to melt the paste, forming a mechanical bond and an electrical connection. Solder paste application is required with the SMT assembly process but not with Through Hole PCB Assembly.

Component Placement

Once the solder paste is applied, the board is ready for the placement of the required components. In the Through Hole PCB assembly process, the components can be positioned on the board by hand. However, this process can be labor-intensive and requires the expertise of a highly skilled technician. In the SMT assembly process, components are placed using robotics and automated systems. While automated systems can place components faster and with the same precision, some applications require hand placement.


With the components in place, the board is ready for the reflow stage of the PCB assembly process. In this stage of the process, the entire board with its components moves through an infrared oven which heats the solder, causing it to liquefy and creating the necessary connections. After exiting the oven, the board moves into a cooling area where the solder cools and solidifies, forming a permanent bond. The Through Hole PCB assembly process does not require the reflow step. Instead, because of the manual placement process, the board is inspected, and any issues with component placement are corrected.


After the solder has cooled, the board, soldering connections, and components are inspected. Due to the increasing complexity and miniaturization of circuits for today’s electronic devices, advanced inspection and quality control techniques are used. The inspection step is vital to ensuring the quality and reliability of the PCB and assuring that it performs consistently in various electronic devices.

Through-Hole Part Insertion

A through-hole part is a device that is soldered and mounted to the board. First, the components are placed with the aid of lead-plated holes. After placing the elements in the appropriate hole, the soldering is performed. The quality of the solder joint and resulting connection are essential factors in the manufacture of PCBs. The strong mechanical bonds made with through-hole part insertion offer superior quality. The soldering of these components can be done manually or using wave soldering, a type of bulk soldering process where the entire board moves over liquid solder before moving through a cooling system to solidify the solder.

Final Inspection and Cleaning

The last step of the PCB assembly process is a thorough inspection of the entire finished board. This final step includes an examination of the components and solder points as well as a careful cleaning to remove any debris or excess solder.

Choosing The Right PCB Assembly Process and Supplies

There are several different PCB assembly processes, and choosing the best one for your requirements can be challenging. Therefore, it’s critical to work with an experienced team of experts specializing in PCB assembly to ensure that the end product exceeds expectations.

Additionally, using the correct supplies is critical to ensure the highest quality throughout the entire process. Product designed for electronics assembly, such as SuperSaturated SmartWipes® and GlobalTech® Chemicals provide innovative and unique formulations for use in electronic assembly manufacturing and precision cleaning applications. These environmentally responsible solvents provide safer, better-performing, higher-quality and more eco-sustainable products, packaged in convenient delivery systems for optimum value and utility.


Notes, Electronics. “PCB Assembly and Production Process.” Electronics Notes. Web