Solder literally is the glue that holds all of our electronics projects together.

Without solder, we’d just be threading components into circuit boards and relying on gravity to maintain the connection.

What Is Soldering?

Soldering is the process of connecting two electrical components together by melting a filler metal (solder) with a hot soldering iron to create a strong mechanical connection that allows for electrical conductivity.

As solder is designed to have a lower melting temperature than that of your electrical components, you can be sure that the process will not damage them making it the perfect filler metal for the job.

There are three basic forms of soldering that use different solder alloys meaning that you’ll also need to use different temperatures in order to melt the filler metal. The three basic forms of soldering are:

• Soft soldering – This is the general use solder that you’ll be using in electronics that utilises a low melting point alloy to create a conductive connection between two components.
• Silver soldering – This generally creates a stronger and less brittle joint which is needed for structural integrity. This will generally create a stronger bond than soft solder.
• Brazing – This occurs at much higher temperatures and is primarily used to join pipes where strong connections are essential. Brazing requires a larger amount of overlap or joint to develop the full strength of the bond.

Basic Tools Needed To Solder

If you’re just starting out, you’ll need to make sure you’ve got your work station all set up and ready to go. Thankfully, you don’t need too many bits and you don’t even have to spend that much money to get your solder station all set up.

The basic tools you need to get started with soldering are:

1. Soldering Iron
2. Soldering Iron Tips
3. Solder Sponge
4. Soldering Iron Stand
5. Solder
6. Desoldering Braid
7. Helping Hand
8. Safety Goggles

Let’s dig into these a bit more shall we?

Soldering Iron

Soldering irons are the handheld tools we use to melt the solder between components in order to form our electrical connections.

Soldering irons very simple tools comprised of a heated metal tip an insulated handle. They come in all shapes and sizes with a wide range of different features. Some come with stands and others are simply connected straight to the mains cable.

Once you really get into creating your electrical circuits, you may want to spend a bit more money on a temperature-controlled unit that will all you to set the heat you wish to run at. Other non-temperature controlled models will run at a set value that you need to research before purchasing.

Soldering Iron Tips

As the name suggests, the soldering iron tips are the end of the soldering iron that you use to heat the solder and the necessary joints. Depending on the soldering iron, these are more often than not interchangeable.

Choosing the right soldering iron tip for the job is almost as important as choosing the right soldering iron itself. If not more so.

While a larger tip will maintain its heat better, it can be far too large for many electronics projects. However, a smaller tip can make it much more difficult to get the coating of solder we need in order to make our connections.

Soldering Iron Sponge

We need to keep the soldering iron tip clean if we want it to last a long time and continue to make clean connections.

Soldering iron tips will eventually oxidise and turn black if not properly maintained. This means it will no longer accept solder forcing you to replace it.

The best way to remove this oxidation and keep your soldering iron tips clean is to use a damp sponge or a piece of brass wool.

As soldering irons tend to run at such high temperatures, continuous use of a damp sponge will eventually shorten the lifespan of the tip due to the drastic change in temperatures. To lengthen this lifespan further, try to use bass wool wherever possible. Using brass wool will also mean you don’t have to wait for the tip to return to its optimal temperature before getting back to work.

Soldering Iron Stand

Soldering irons generally run at a temperature of 330°C to 350°C (626°F to 662°F), which means you can’t just lay it on the table or workbench when it’s not in use.

This means we need to rest it in a stand that will ensure the hot tip doesn’t touch any surfaces that would otherwise be damaged/

Most soldering iron stands come with a built-in sponge to help remove any excess solder which can be incredibly handy when you get into the zone.

Solder

As previously mentioned, solder is the glue we use to hold electrical components in place. It’s a very soft metal alloy that is generally made of tin, silver and copper (Sn-Ag-Cu or SAC).

Up until 2006, most commercially available solder contained lead as this prevented something called Tin Whiskers. This was when tin solder which was available at the time produced small metal hairs, or whiskers, that grew between the metal solder pads short-circuiting the board. As lead can be incredibly harmful to our respiratory system if inhaled, we now stick to lead-free solder.

We can purchase reels of solder quite easily on the internet in varying thicknesses. Anything between 0.4mm and 0.8mm solder will work an absolute treat for surface mounted solder joints but you can go thinner if the circuit requires it.

Desoldering Braid

If you make a mistake and solder the wrong component in the wrong place or a diode the wrong way round, you can use a desoldering braid to help remove the solder so that you can rectify your mistake.

Desoldering braid, also known as solder wicks, are made from finely woven copper wires that are often coated in flux to help soak up the solder.

There are other methods of removing solder from a connection but a desoldering braid is generally the most cost-effective way to go for beginners.

We’ll get on to how desoldering works a little later on, but you can jump this by clicking here.

Helping Hand

With one hand on your soldering iron and the other on your solder, it makes sense to have something on your workbench that you can use to hold the circuit board you’re working on.

You can use something as simple as a tabletop vice to grip the circuit in place whilst you’re adding your components.

Alternatively, you could use a Helping Hand to grip the circuit board whilst adding a little more flexibility in how you position it. This can make it much easier to get to those hard to reach places.

Some helping hand systems also come with a magnifying glass to help you see the layout of the board a little easier and crocodile clips to provide even further gripping possibilities. Depending on the complexity of the project, these extra features can be truly invaluable.

Safety Equipment

When you’re getting into your soldering, you’ll notice that it can sometimes give off a lot of smoke that can be harmful to both your lungs and your eyes with prolonged exposure.

While it doesn’t happen too often, molten solder can make a splash and whilst you’re in the thick of it, odds are, you’ll be fairly close to the circuit board.

As a safety precaution, it’s highly recommended that you only do your soldering in a well-ventilated area, wear protective glasses and a face mask.

How To Solder?

Now that you have all of the tools and equipment needed to get soldering, lets run through how to actually solder.

Preparation

Before actually soldering your components to the board, we need to do a bit of preparation.

Choose & Attach A Soldering Iron Tip

Before turning on the soldering iron and letting it heat up, we need to choose the correct soldering iron tip for the job. The wrong tip can not only make it difficult to solder your joints, but it can sometimes even damage the components you’re looking to join.

Once you’ve chosen the correct tip for the job, make sure it’s tightly screwed in place and place the soldering iron in its stand.

Heat Up The Soldering Iron

With the correct soldering iron tip now in place, we can turn it on and get it up to the correct temperature. If you have a temperature-controlled soldering iron, it’s recommended to set this to 400°C (750°F).

If your unit doesn’t have a light to tell you when the soldering iron is up to temperature, it should only take 30 seconds to heat up.

Clean The Soldering Iron Tip

Once the soldering iron has heated up, it’s time to clean the tip ready for use. Use a damp sponge to remove any dust or grime that may create connection issues for the solder and then place the soldering iron back into the holder to heat back up.

Tin The Soldering Iron Tip

With your soldering iron in one hand and your reel of solder in the other, evenly coat the tip of the soldering iron. This must be done before and after every soldering session to prolong the life of the soldering iron tip. 

If the tip of the soldering iron is rough or looks slightly porous, it’s time to replace it with a new tip.

Clean Components & Board

To ensure you have good connections throughout the circuit, it’s always recommended that you clean all of the components you’re going to be using along with any PCB’s/Vero boards. This can be done with a dry piece of cloth and the aim is to remove any greasy fingerprints, dust or anything else that may have come into contact with the components.

Any grease on a joint may make it more difficult to solder later on, so getting this step out of the way just before you’re about to start is a great idea.

Soldering Your Components

Now that you’re all set up, soldering iron is up to temperature and your components are cleaned, it’s time to begin soldering

Tin The Components

It’s much easier to make a solder joint if both components have solder on them already. By adding a small amount of solder to the components before adding them to the PCB, you make it much easier to make the solder connection later.

Position The Components

Grab all of your components and thread them into the PCB making sure that the wires are bent to hold the pieces in place.

It’s a great idea to get as much in place as possible before soldering the components onto the board. A dry run before actually creating the solder connections can help plan out the placement of everything and will save a lot of desoldering time down the line.

Apply Solder

When you’re happy that everything is in place and will fit in the desired enclosure, we can begin soldering the components into place.

To do this, try to heat up both the component and spot of the board where the component is going to be placed. The tinned elements will make a bit of a connection, but by applying additional solder, we can make a strong connection.
Try not to leave the soldering iron on the component for too long when adding more solder as it may damage it.

Leave To Cool

While the solder in your joints will set almost immediately, the components will still be hot. It’s best to leave things a couple of minutes after you’ve finished to let the heat dissipate.

Check Connection

Once everything has cooled down, check the solder spots from all angles to make sure you’ve created a solid connection. Any joints that haven’t been fully filled with solder could create issues for your circuit.

If everything looks fine and the components have cooled, try to give it a little wiggle. If there is any unexpected movement, it would be well worth adding a bit more solder to solidify the connection.

Finishing Up

All of your components are soldered in place and everything looks good, but what’s next?

Snip Excess Wires

Before turning off the soldering iron, you need to give it a clean ready for its next use. The best way to do this is it dab it in your steel wool to remove any excess solder.

It’s also then recommended that you retin the tip ready for your next use. This keeps the soldering iron tip from rusting/oxidising which will help make it last much longer.

Clean Board

Now that you’re done, you can give the board a final rub down with a dry cloth to remove any dust, grease, fingerprints or scorch marks from your soldering iron.

As with anything thats worth doing, soldering takes practice to get right and you’ll have some real stinkers before your happy with your joints but the more you can practice it, the better you’ll become and the more enjoyable you’ll find it.