Soldering Techniques for Printed Circuit Boards (PCBs)

Soldering techniques for printed circuit boards (PCBs) are essential for anyone who wants to work with electronic circuits. The soldering process includes joining two metal surfaces with a filler metal called solder. This article will discuss some of PCBs’ most common soldering techniques.

Through-hole soldering:

Through-hole soldering is one of PCBs’ oldest and most common soldering techniques. It involves inserting components into pre-drilled holes on the PCB and then soldering the leads of the components to the pads on the opposite side of the board. This technique benefits large parts, such as connectors or transformers, which require mechanical support.

To perform through-hole soldering, you will need a soldering iron, a soldering stand, a flux pen, solder wire, and a pair of pliers. Start by cleaning the tip of your soldering iron and then applying a small amount of solder to the tip to help transfer heat. Next, apply flux to the pads on the PCB and insert the component into the hole. Hold the component in place with a pair of pliers and then apply heat to the pad and lead using the soldering iron. Once the solder has melted, remove the iron and allow the joint to cool.Soldering techniques for PCBs

Surface-mount soldering:

Surface-mount soldering is a newer technique for small electronic components that do not have leads that go through the PCB. Instead, they have pads on the surface of the PCB to which they are soldered. This technique is beneficial for small electronic devices such as smartphones and laptops.

To perform surface-mount soldering, you will need a hot air reflow station, a flux pen, solder paste, and tweezers. Initially, the flux is applied to the SMD pads, then a small amount of solder paste is printed on the respective SMD pads. Due to tiny components, the components cannot be hand placed. In this case, tweezers will help place the components on the paste with proper alignment. If this process is done manually, tweezers can help place the components on SMD pads. After placing the components, the boards go into the hot air reflow over or station in which they are pre-heated for a specific period, and as time increases, the heat melts the solder paste and glues up the components on the PCBs. After the process the board heating process, the machine decreases the temperature to a certain amount with time to cool down the assembled boards. Most EMS providers perform these tasks through automated pick-and-place machines, which help achieve accuracy and save time.


Wave soldering:

The wave soldering process helps assemble high-volume quantities with through-hole components. It helps all the through-hole components to get soldered in less time and with accuracy, as suggested by IPC. The process starts by passing the PCBs over the molten solder wave, which touches with the Plated through hole components leads and creates a strong joint between the board and the components.

Wave soldering machines are industrial machines primarily available at Electronic Manufacturing Service providers like PCB Runner. The required types of equipment are similar to SMD, like a flux applicator, solder wire, and a pre-heating station. The process starts with applying flux on the PCB and placing the Through hole components by hand. After placing all the components, the boards are passed through the pre-heating station to warm up the PCB and settle the flux on the PCB. After the PCBs are placed on the rail, the rail takes the PCB forward to the molten solder, which wets the pads and creates strong solder joints between the components and the boards. After a successful trip of molten solder, the PCBs get into a cooling station to cool down the molten solder.

In conclusion, soldering techniques for PCBs are essential skills for anyone working with electronic circuits. Through-hole soldering, surface-mount soldering, and wave soldering are the most common techniques used for PCBs, each with advantages and disadvantages. Understanding the different techniques and their applications allows you to choose the most appropriate technique for your project and produce high-quality solder joints.