A Complete Guide to Soldering Irons

A soldering iron is the primary piece of hand-held equipment used in the process of soldering, wherein a small quantity of fusible metal alloy - known as solder - is heated to a high temperature with the tip of the iron.

As it melts, this solder material is directed to flow into the spaces between and around two components or workpieces. Once bonded, the solder is then left to cool and harden, creating a fixed and conductive join that remains permanent until reheated sufficiently to melt the solder back into liquid form. This process of reheating and separating a previously soldered join is called desoldering.

Soldering irons are typically plugged into a wall socket in order to deliver their heat electrically via an elongated metal tip containing a heating element, although various different types of cordless models are also available. The user holds the iron at the other end from the heated tip, where an insulated handle provides a convenient grip for enhanced accuracy in manipulating the tool around small or delicate components.

In terms of the sheer number of things it can be used to build, fix, augment or disassemble, the full range of potential soldering iron uses is effectively limitless. However, all of this incredible versatility can be categorised under two core functions - soldering and desoldering.

Soldering involves allowing the heated tip of the iron to reach very high temperatures before using it to melt the solder wire around the components that will be soldered. As it cools back to room temperature, the bond will solidify and become permanent - at least until it is desoldered.

Tool temperature is critical, as the soldering iron must get hot enough to melt the solder to a liquid state, but without melting or damaging the components. Some more advanced models of iron will include an adjustable temperature feature, offering enhanced control and greater compatibility with a range of different solder types. However, the majority will simply heat themselves to a preset level automatically on connection to the mains or another suitable power supply.

The basic process of soldering is broadly seen as fairly simple and straightforward. However, knowing exactly how and when to use a soldering iron for the best possible results is something that professional engineers continue to develop over years of dedicated use, and learning the proper techniques for achieving a neater, more effective join can demand a significant level of finesse and experience.

For help learning how to solder, you can read our beginners' guide to soldering for more handy tips, safety advice, and assistance learning the best soldering techniques for a variety of different scenarios.

There are many different types of soldering equipment and kits available to both hobbyist and professional users alike, ranging from basic fixed tools to a wide range of interchangeable add-ons, extras and accessories. In the section below, we will look at some of the options you might like to consider, depending on how often you will be using your soldering iron and the sorts of jobs you are likely to be doing with it.

Why Use a Soldering Station?

The most obvious difference between soldering stations and soldering irons is that they usually provide the ability to dial in a range of specific temperatures, rather than just one fixed heat setting as you will tend to have with a standalone tool.

A soldering station’s temperature control dial can be either analogue or digital; the latter is much more common these days and tends to offer a far greater degree of accuracy for heat-critical applications.

In the simplest terms, desoldering is the opposite of soldering. In other words, it means to remove solder from an existing join, whether for complete disassembly or simply as the first step in improving a weak bond during everyday troubleshooting applications.

However, although desoldering can be a pretty basic job, it is still important to follow the correct process and ensure the task is done correctly.

Why Desolder?

There are numerous reasons why you might need to desolder an existing bond between components or workpieces.

Essentially, the main aim of any desoldering job is to cleanly remove melted material (be it wire, flux or paste) from the location you are working on, such that the component can be reseated and a better bond can be created at the next attempt. As such, the three basic steps in any desoldering operation will be as follows:

1. Heating up the old hardened solder material, to return it to a liquid state
2. Removing the attached wire or component carefully without damaging anything
3. Cleaning up the existing solder to provide a neat surface for remounting

Numerous techniques and tools exist for achieving these basic goals but the simplest version is just to reheat the old solder with a simple fixed-temperature iron. While this will not offer many options for a high-finesse job, it can be effective if you just need the basic ability to remove a component.

For more detailed work, or to give yourself a better chance of removing all traces of previous soldering jobs, you might like to consider any of the following:

It is important to take good care of irons, tips and other soldering accessories in order to prolong the useful working life of your soldering tools and equipment. Among the most basic forms of maintenance and upkeep you can perform with this type of equipment - much like with any other tool type - is regular soldering iron cleaning.

The easiest way to clean soldering iron tips is simply to manually wipe off any build-up of debris from previous sessions - examine the tips for any residual bits of solder and carbon. However, with heavy use, you may find that further cleaning is required.

For best results, it is generally recommended to also make regular use of an iron brush or a solder iron cleaning sponge. These are often sold in a kit, consisting of a cleaning tray and either a sponge material of flux and powdered solder or a spiral ball of dry metal wool. More advanced tip-cleaning kits leave you with a fine solder layer across the tip, which helps to prevent tool oxidation over time.