How to Solder - A Beginners' Guide to Soldering

From electrical engineering professionals to hobbyist DIY fixers, lots of people regularly use a technique known as soldering to perform routine assembly, maintenance and troubleshooting tasks on all manner of workplace or domestic items and equipment.

Soldering is an especially common requirement for jobs involving circuit building, PCB assembly and electronic prototyping. However, it can also prove to be an extremely useful and effective technique for joining two or more surfaces together in a wide range of other, more general applications.

In short, soldering is a common and fairly straightforward method for affixing or bonding various types of materials and components to one another. The process is carried out using a small amount of metal alloy, known as solder, and a heated handheld tool called a soldering iron. When you solder items together, you’ll typically be using the hot metal tip of the iron to melt a small amount of solder alloy around and between the components or surfaces being joined.

Once cooled and hardened, the resulting soldered bond or joint is considered to be permanent. It will provide a secure, electrically conductive (for circuitry) and watertight (for plumbing applications) connection between discrete parts. However, it’s worth noting that hardened solders can usually be remelted and removed fairly easily through reapplication of sufficient heat. This often allows for parts that have previously been soldered together to be separated or reworked as necessary. This process is known as desoldering, which we’ll come back to later.

In this beginners’ guide, we’ll offer a quick overview of proper soldering techniques for a few different scenarios and component types, while providing handy tips on how to use soldering irons and other key tools safely and accurately. We’ll also discuss which types of products, kits and soldering iron accessories might be best suited to various different jobs, answering some basic FAQs about general equipment use and maintenance.

As with all DIY activities involving potentially hazardous tools or conditions, safety awareness should always be a top priority in preparing for soldering work. As ever, this includes making sure that you’ve got the right PPE equipment in place prior to starting the job. It also means ensuring that the surrounding area is well-prepared and as free from unnecessary hazards as practically possible.

In addition, it’s important to know the key basics about how to solder safely before you carry out any work. For beginners, there are various aspects to safe soldering that you need to be aware of in order to solder correctly while presenting a minimum risk to yourself, your tools, and your environment.

The most obvious hazard is the soldering iron tip, which needs to get extremely hot in order to perform its primary function. Even basic models that plug directly into a wall socket and offer no manual temperature control (typically a feature of soldering stations, allowing for fine-tuning of iron performance) will usually heat up to around 400 degrees Celsius very quickly. This is easily hot enough to cause severe burns if handled incorrectly.

More advanced models and various add-on accessories may provide a number of reassuring built-in safety features. However, even versions bought as part of a comprehensive soldering iron kit can carry plenty of potential to cause serious and lasting injury if used carelessly.

In addition to the extreme heat involved, there are several other potential dangers to look out for when soldering. In particular, it’s important to be aware that solder material itself can occasionally ‘spit’ when superheated due to air pockets or impurities. This means that protective eyewear is a must, especially for beginners.

Furthermore, the majority of solder pastes and compounds contain toxic elements such as lead and rosin - it’s always sensible to wear gloves when handling soldering tools and materials, and to ensure proper ventilation of your workspace is available before starting a job.

Before Soldering:

• Read all product instructions and safety guidelines thoroughly, and make sure you’re aware of the common risks
• Read solder ingredient lists and documentation carefully. Check directly with suppliers or manufacturers if not enough information about potential toxicity is provided on the label
• Make sure that your work area is clean, tidy, stable, and free from sources of ignition
• Check that you’re working in a well-ventilated area with suitable fume extraction available
• Always wear safety glasses, and use heatproof gloves for handling materials
• Check that you’re using the right type of product for the task at hand - soldering irons come in various different sizes and wattages, often intended for specific sorts of applications
• Do not use any soldering iron or other item of electrical equipment that shows visible damage to the tool body, cabling or plug
• Always know where your nearest fire extinguisher and fire exit routes are

During Soldering:

• Never attempt to solder live/powered circuits, terminals, connections or components
• Keep soldering iron cleaning accessories such as wire pads and damp solder sponges close at hand, ensuring that the iron’s tip is kept as free from material build-up as possible during use
• Never touch the soldering iron anywhere except the insulated handle (sometimes referred to as the ‘wand’)
• Always use tweezers and/or gloves to hold surfaces and components that are being (or have recently been!) soldered
• Be wary of potential spitting from molten alloys, and keep safety glasses on at all times while melting solder
• Always return the iron to its cradle or stand when not in use - never lay it directly on a work surface, table or bench
• Check that the stand is sufficiently weighted or stable enough not to easily topple if you should accidentally snag a cable - if this does happen, do not attempt to catch the iron mid-fall
• If you do suffer a burn, immediately hold it under cold running water for a minimum of 10-15 minutes before following any necessary first-aid procedures
• Always switch the soldering iron or station off at the plug socket if you need to leave it unattended at any point

While there are numerous tips, techniques and rules of thumb for general soldering work that apply more or less universally regardless of the type of job you’re doing, some specific fixes demand a more bespoke approach. You can also buy a wide range of soldering iron adapters and add-ons for making particular sorts of work far easier and more efficient.

In the sections below, we’ve listed a few different areas, types and techniques in soldering that are useful to get acquainted with if you want to be able to turn your hand to a wider range of soldering tasks.

How to Solder a Wire

For most people, an ‘everyday’ soldering task might involve fixing or improving an existing electrical connection. Very often, that can require knowing how to solder a wire - or, more specifically, how to solder two wires together. This would broadly be considered as a fairly standard, common example of a soldering job, and is generally very achievable using a basic set of common tools and materials.

How to Solder a Circuit Board and PCB Board

When it comes to knowing how to solder circuit boards, it’s worth noting that there are a couple of different techniques used specifically for electronic soldering - and particularly for adding components to a printed circuit board (PCB). Most PCB components are designed to be mounted in one of two ways - using either a through-hole method or a surface mount method. The correct approach in any given scenario will be dictated by the type of board and component that you are working with.

How to Solder a Copper Pipe

An alternative job involves knowing how to solder copper pipe correctly. Unlike most other types of joint soldering (particularly electrical/PCB work) the aim when soldering copper pipe is often to achieve a leak-free joint. The goal is to end up with reliable and consistent water flow through two or more lengths of tubing.

This requires a rather different set of tools and techniques than standard benchtop soldering work. Most notably, you’re likely to want either a gas blow torch or a purpose-designed plumbing soldering iron for applications involving ducting and pipework. As a result, the physical process of actually heating and sealing the joint with solder is also different.

Good quality interchangeable soldering iron tips are among the most important parts of a soldering iron setup, and a staple of any well-stocked kit. They do the brunt of the work during soldering, transferring heat from the iron into the alloy in order to melt it and allow it to flow into joints between two components or workpieces.

These tips are available in numerous different sizes and shapes for specific tasks and are also sometimes referred to as ‘bits’. Some of the most popular varieties of soldering iron tips can be found below.

What is a Soldering Iron?

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. 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.

What is a Soldering Station?

A soldering station forms the basis of a slightly more advanced setup, adding a separate control unit to a standalone soldering iron. This allows users to dial in a range of specific temperatures for different sorts of work, either digitally or via a dial (the former is much more common these days). Various sorts of soldering station accessories can also be purchased, providing a range of additional advanced features, functions and benefits to most base model soldering stations.

What is Solder?

Solder is a metal alloy with a low melting temperature point, used alongside a soldering iron to permanently join together two metals with a higher melting point. The majority of solder comes in the form of a coiled length of wire, or less commonly as pellets, with a range of diameters or gauges available to suit various applications and joints.

Solder pastes are ideal for use on PCBs and for connecting surface mount electronic components - this is a sticky non-drip compound, often applied to a board by printing or painting. Solder granules are also available for specific types of soldering machines and tinning crucibles.

How Do You Keep a Soldering Kit Clean?

There are numerous different types of soldering iron cleaning accessories available online, and these form an important part of any kit - proper, regular cleaning and maintenance of soldering iron tips (both during and between jobs) is key to getting the best results and developing a safer, more efficient soldering technique.

Examples of cleaning products to keep as part of your soldering iron kit include:

• Iron brushes
• Soldering iron cleaning sponges (used damp)
• Metal wool (used dry) - often referred to as a ‘brass sponge’
• More advanced tip-cleaning kits can also leave you with a fine solder layer across the tip as part of the cleaning process, which helps to prevent tool oxidation over time and improves the longevity of replaceable tips

What is Desoldering?

Desoldering is the process of removing hardened solder material from a previously soldered joint, surface or component. With enough care and expertise, this can be done using a regular iron - however, a number of dedicated tools and desoldering accessories exist for making the job much easier and neater. These include:

• Desoldering braid (or wick)
• Desoldering guns and pumps
• Desoldering gun tips