How to Solder Electronics: A General Guide

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For electronics projects, breadboards are often used to create a working prototype. This is the stage where it is okay to have many wires coming from the breadboard, as the main challenge is to see that the prototype does indeed work. After this, you probably want a more tidy layout with perhaps a custom-built PCB (printed circuit board). To add the components such as LEDs or sensors, you will need to be able to melt and apply solder precisely to join parts together. This soldering guide shows you how to solder and solder well, for use in your electronics projects.

Note: if you are soldering parts to your Raspberry Pi, you will need to get the right case to accommodate your add-ons.

What Basic Equipment Do You Need for Soldering?

Let’s say you have a Raspberry Pi board that needs header pins soldered to it. For this, you will primarily need a soldering iron, solder (the coil), and preferably some flux.

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Raspberry Pi boards without header pins.

Alright, let us look at each of the soldering tools one by one.

Soldering Iron

The soldering iron is the main piece of equipment you will need. Sometimes they come in a kit with other equipment but not always. The first thing to check before buying a soldering iron is what kind of a plug it has. Some are portable and can be charged via USB-C but most plug into the wall.

Next, check the power of the soldering iron, which generally ranges from 20W to 60W. For example, you may struggle to melt the solder in some instances with a soldering iron with a low wattage. It is important to also check the efficiency of the soldering iron to transfer heat to melt the solder. A simple or hobbyist 20W soldering iron may lose heat when it is being used and will not have a temperature control to compensate for that loss.

Some soldering irons are more advanced and allow for the power or the temperature to be controlled. These are usually part of a soldering station and not a soldering iron with a plug attached. Soldering stations allow for more accurate soldering with a higher degree of temperature control.

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A well-used soldering iron.

Other items to check that are related to the soldering iron include:

  • The price – varies depending on whether it is a simple soldering iron or a soldering station and how well made it is.
  • Added extras – includes any extra tips for the soldering iron and, optionally, a stand or holder.
  • Aesthetics – can include color and style, which depends on your preferences.
  • Materials – includes the grip and how well made it is, which is important, as it gives you good control while soldering for a long time.
  • Warranties and build quality.
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Soldering using a stand with clips (helping hands) to hold the electronics project.

The Solder

This second most important piece of equipment is the solder wire. Solder comes as a coiled wire and is made up of metal alloys, which are melted by the soldering iron. When it cools later, it joins together the parts or components. The most obvious difference between solder is the diameter of the solder. If you have small and delicate components to solder, you may need the smaller diameter solder of 1mm or less. A larger solder would be about 1.5mm in diameter.

Solder can come with flux already included inside the wire. This helps the solder to melt and flow. Lead used to be used in solder, but since it is toxic and a health hazard, lead-free solder is more commonly used and is recommended.

Wool or Sponge

A wet sponge or coiled brass wool is necessary to keep the tip clean between soldering stints. I strongly recommend getting brass wool since it is a cheap,. yet useful tool. The alternative is a wet sponge that can also remove the excess solder from the soldering iron tip, but the water will lower the temperature of the tip, affecting your soldering.

Desoldering Wick

Since not everyone is perfect, you will need desoldering wick to remove any mistakes that you make. Desoldering is the process of removing solder that was previously applied. You will also need a desoldering wick to help you remove components that are old or that you want to replace.

As you heat the component and solder, place the wick on the solder. The wick absorbs the excess solder, then you can cut off this end of the wick that is saturated with solder and throw it away. Then use a fresh part of the wick when you need to to make further corrections.

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The main tools for soldering electronic components: the soldering iron at the top and left to right at the bottom: brass wool, solder, and desoldering wick.

Extra Tools for Soldering

Soldering Flux

Flux is your best friend when soldering. I like the type that comes in a syringe and go through a lot of it. It makes you look like a pro and helps the solder to go only where it is supposed to. Not all flux is the same, though, so you will need to look for reputable manufacturers that make a good product. Many types of solder include flux on the solder itself; however, I still recommend using extra flux in a syringe for nice shiny soldering. There are also rosin flux pastes that can be used.

Helping Hands

Sometimes you have more wires and parts to hold then you have hands. This is confounded by having to hold the solder iron in one hand and the solder in the other. It is at these times that you need some helping hands, otherwise known as a third hand. Helping hands are generally made with two or more metal clips that hold your parts and allow you to focus on the soldering.

Magnifying Glasses

Many of the components that you have to solder are very small. Also, after soldering, it is a good idea to check your work closely to ensure that the solder didn’t accidentally join parts together that needn’t be. This is where a magnifying glass, or even a microscope, is a good tool to have, as it allows you to see these small components.

The Proper Soldering Technique

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Soldering metal header pins onto an LCD display with a conical tip soldering iron.

Choosing Your Soldering Iron Tip

The main types of tips are chisel or conical. The chisel-shaped tip is flat and relatively broad and is useful for components that fit through holes and are soldered this way. The conical-shaped tip is like the cone-shaped tip of a pen and useful for soldering small and fine components. Most soldering irons come with a conical tip by default, but it is useful to have tips of different diameters.

The next step is to let the soldering iron heat up, then add some solder to the chosen soldering iron tip, in a process called tinning. This allows the heat from the soldering iron tip to be transferred to the solder. Clean the tip in the brass wool, then put the solder to the tip to allow a little solder to melt onto the tip.

Putting the Heat Where It Needs to Be

If you have a soldering station, you can choose the required temperature for the part. You should remember to heat the metal part of the board or the component and not to just heat the solder itself. The solder wire will be fed onto the heated area and will melt on contact with it.

Adding the Component

The component that you need to solder could include something simple like an LED (light-emitting diode) or something more complex, such as a chip. If it is a through-hole soldering, take the metal leads of the component and place them through the desired holes. Liberally add some trusty flux to the area being soldered. With the tinned soldering iron tip, heat up the metal around the hole and the metal lead at the same time. After a few seconds, apply the solder to the heated parts to join them.

After you add the solder, clean the tip with the brass wool or sponge, put the soldering iron safely back in its holder, and turn it off if you are finished with it. You can snip off any excess wire from the component once the solder has cooled. If you are soldering wire, remember to remove any polymer insulation from around the wire so that you only solder the metal wire itself.

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Soldering a component onto a PCB, showing the soldering iron on the right and the solder on the left, photo by Unsplash.

Practice Makes Perfect

If you are new to soldering, it is recommended to first practice on something like perfboard (perforated circuit board). Perfboard has metal-ringed holes, into which components can be added. There is perfboard with metal on both sides and perfboard with metal rings only on one side.

Safety Concerns and Best Practices

Extractor Fans

Extractor fans are useful so that you do not breathe in the fumes as you concentrate intently on the soldering. This is especially true if you are using solder with lead (which I would not recommend, as it is toxic). It is also a good idea to wear gloves or wash your hands after soldering.

Clear Workspace

Since the tip of the soldering iron is hot, it is important to keep your desk or workspace free of paper or anything flammable. These items can catch fire when you are not paying attention, as the soldering iron tip takes time to cool down.

Turn Off Your Soldering Iron

The soldering iron may not glow red hot, even though it is hot enough to burn skin if touched. You should especially be careful if children or those who don’t know about soldering irons are close. Turn off your soldering iron as soon as you are finished with it and make sure it cools down to room temperature before you leave the area.

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A soldering station. Switch your soldering iron off and place it in a holder while hot. Practice safe habits from the start.

Avoid Static Discharge

It is a good idea to ground yourself and your work area when working on electronics. A grounded anti-static wrist strap is a good option. Another is to use an anti-static matt.

Check Your Soldering Work

After soldering parts, do check how well you soldered everything and that it is attached securely. You can create a short if there are fine strands of solder joining areas that should be separate.

It is good practice to check the job afterwards using a magnifying glass or microscope, cleaning up any dirt with 99 percent pure isoproponal (rubbing alcohol) and a Q-tip or cotton bud while wearing latex gloves. If there are problem areas, don’t fret, as you can usually use the soldering wick or braid and the soldering iron to remove the excess solder and redo.

Soldering is useful for projects including those with microcontrollers, such as starting out with an Arduino board kit, or for projects with Raspberry Pi or other single-board computers.

Frequently Asked Questions

Can I solder my own Raspberry Pi?

The Raspberry Pi is almost complete, so dit oes not require much soldering on the SBC itself. But after becoming competent by practicing on perfboard, LEDs and other cheap components, you can solder header pins onto your Raspberry Pi if it doesn’t have them already.

Is it alright to solder my own Arduino?

The Arduino boards are compatible with many expansion boards, known as “shields.” Many of these shields need components soldered to complete them. Some of these shields come in Arduino starter kits. Once you have spent a lot of time practicing to improve your technique and learn to solder safely, you can solder these for your Arduino projects.

Do I need a set of helping hands for soldering?

Helping hands are just that: they help hold the components and parts while you solder. You don’t need them, as you can make your own from clips, but they do help when you have complicated soldering with many parts. You only have two hands unless you have a friend who is patient iwth steady hands, but if you need more, helping hands will be very useful.

Image credit: Unsplash. All other photographs were taken by the author.

Graham Morrison
Graham Morrison

Graham is a tech enthusiast. He is a scientist with a background in engineering. He enjoys writing and has been doing so for over 10 years.

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