How to solder: Best Tips

Today I'm going to be showing you how to solder wires together. Soldering is an essential skill for anyone working with electronics, and knowing how to solder properly can be invaluable.

I also made a video about how to solder which you can see on YouTube below:

Solder is a metal alloy with a low melting point used to join wires together. When you solder you're not melting the metal you're soldering to, you're heating both pieces of metal up to allow the solder to flow between them.

It's important to note that soldering is a durable electrical connection in this case and not a strong mechanical one. If you're soldering wires together, or other components, the strain shouldn't be on the solder joint.

These are the tools and consumables you need to solder correctly:

soldering tools

-Soldering iron

-Flux

-Solder

-Heatshrink

-Wire strippers

-Heat gun or Hair dryer

-Safety glasses

-Set of helping hands

-Wet sponge

-Dielectric grease

Links to the tools mentioned are at the end of the post so you can find them easily.

These are two alternative soldering irons if you're working remotely and don't have access to power, a cordless soldering iron

milwaukee soldering iron

Butane gas powered soldering iron

gas soldering iron

Before we get started let's take a look at a few safety considerations when soldering.

It's important to wear safety glasses when you're soldering to protect your eyes from spatter or excess solder.

The tip of the soldering iron is very hot so make sure you don't rest it on anything flammable and be careful to not make contact with your skin.

Keep any flammable items like gas cans, or fuel away from you whilst soldering as well.

Some solder contains lead so make sure you work in a well-ventilated space, outside or set up a fan next to your workspace.

After your finished soldering, lean your workspace and wash your hands especially before eating food.

With these safety precautions in mind, its time to begin soldering and soldering is simple to do. What makes it so simple, is using the right selection of tools and the correct solder.

Solder has three main types. Leaded solder, lead-free solder, and silver solder.

3 types of electrical solder

Silver solder should not be used due to its acid core. Over time the acid will eat away the plastic insulation on the wire and cause problems in the wiring.

The 2 options for electrical solder are leaded and lead-free. Lead-free has a higher melting point so your soldering iron has to be hotter, and it's more responsible to use environmentally.

Leaded solder has a lower melting point and is easier to solder with, I use it for all soldering jobs on cars and anything else.

I use 60/40 resin core solder which works the best due to the resin cleaning the wires of surface oils and contaminants before the solder surrounds the wire and it also prevents oxidization until it cools off.

You might have an unlabelled roll of solder at home and you're unsure if its lead or lead-free.

A quick test is to do two balls of solder on metal and see if the finish is a matte grey or shiny silver. Shiny silver means its lead solder and matte grey is lead free. So that's a quick test you can do.

lead solder lead free solder

I already mentioned that I like using resin core solder because the resin protects the wires from oxidisation but I like to go one step further and use a rosin paste flux which is another level of protection from oxidisation.

When you heat up metals like the wire ends your going to solder, or even your soldering iron, as the unprotected surface heats up, oxides form and coat the copper, making it really difficult to solder.

The last tool you need to solder is a soldering iron. There are a couple of options here a corded electric one, a cordless electric one like the Milwaukee or a gas soldering iron shown above.

The corded soldering iron station is good for hobbyists that don't need to be off-site and will easily solder smaller gauge wires and components on circuit boards due to its fine point tip. This iron is 48 watts and works great.

soldering iron station

This gas-powered soldering iron is a great portable option and low cost.

It has an in-built igniter but you will need to carry with you a can of butane gas to operate it.

I prefer the third option of an electric cordless soldering iron, this one has an output of 90 watts and heats up quickly. It can handle thicker gauge wire like this

heavy automotive wire

You can change the tip over if you need to solder circuit board components.

Now that you know what tools are required, I'll be showing you in 5 easy steps, how to solder and going into each step in detail:

soldering in 5 steps

  1. Start by stripping the wires back
  2. Slide on the heatshrink
  3. Splice the wires together
  4. Solder wires
  5. Shrink heat tubing

Step 1

The first step is to strip the insulation off both wires to connect. Simply insert the wire into the pliers and use them to quickly remove insulation. Strip the same amount from each wire to make them easier to join.

stripping wire

If you accidentally break the strands of wire when stripping the insulation, cut the remaining wire strands and start again. If you don't it will cause extra resistance in the wire and therefore heat which can cause the wire to melt and even present a fire risk if the circuit fuse does not blow.

With the wires stripped, it's time for step 2, adding the heat shrink.

Step 2

When it comes to selecting the size of heat shrink, pick the one that barely fits over the wire so that when it comes time to shrink it, there will be a tight seal over the solder joint and wire. Heat shrink tubing shrinks to half its diameter, this should help with picking the correct size.

choosing heat shrink size

Use a piece of heat shrink long enough to cover the exposed wires and part of the insulation. Move the heat shrink far enough away from where you'll be soldering so that it doesn't shrink for the heat generated soldering the wires.

Step 3

Now for the third step, we're going to connect the wires using a linemans splice also taught by NASA to its astronauts. Start by making sure you have enough wire stripped and twist the wire strands tight.

Cross one wire over the other to make an X and wind one wire tightly around the other for at least 3 turns, repeat this on the other side.

splice

Make sure there are no stray bits of wire sticking up that could poke through the heat shrink, all the strands should be flush.

linemans splice

Next, attach your wire to a “helping hands” to keep the wire steady.

helping hands

Add the rosin flux around the wire splice to prepare the wires to be clean when the heat is applied and make the solder flow into the wires when it's added.

adding flux to wires

Then turn your soldering iron on to pre-heat it to the correct temperature. Once it's up to temperature use a damp sponge to clean the tip.

Next we are going to tin the tip of the soldering iron, to do that just add a few dabs of solder and wipe the tip on your damp sponge leaving a thin layer of solder on the tip. The soldering iron is now tinned and ready for soldering. Always clean the tip on your sponge after soldering to prolong the life of the tip.

Step 4

It's now time to solder the wires. Before the copper wires will take solder they need to be heated up. Position the tip of the soldering iron underneath the wires and add a small dab of solder to the tip.

soldering wires

 

This process is quite fast, as the solder melts and heat is ut into the wire it's now ready to accept solder into the joint. Feed the solder directly into the top of the wires and let it wick through the strands.

You don't need to add heaps of solder to the point were its forming blobs, just enough to cover all the strands of wire and fill all gaps in the joint. Once you have added enough solder, remove the soldering iron to let the joint cool. When it's cooling down try not to move it around as this can cause cracks and air gaps in the joint so your joint wont last as long.

After your finished with your soldering iron, with the tip still hot, carefully wipe the tip clean against the sponge. Once the solder has completely cooled, which usually takes about a minute, inspect the solder joint.

Your looking for complete coverage of the joint with solder, the outline of the wires visible is good and you don't want any large globs with exposed copper still visible if this is the case, try again.

This joint looks like a good soldered connect so now it's time for our final step, insulating the wire.

good solder joint

Step 5

To make this connection last a long time and make it waterproof, apply dielectric grease around the solder joint. Then slide the heat shrink over it.

dialectric grease over solder joint

Next apply heat to shrink the tubing with a heat gun or hairdryer, starting in the middle and working outwards. Dielectric grease prevents moisture and insulates the solder joint extending the life of the connection.

add heat shrink

Simply wipe off the excess grease that is pushed out from the heat shrink and you now have a good waterproof connection.

heat shrink solder connection

A very common mistake I have seen over the years is a cold solder joints. This occurs when not enough heat is applied to the joint when it's soldered and instead of adding solder directly to the wire, it's dripped on to the wires like this.

cold solder

To make sure you never have a cold solder joint, always hold the soldering iron beneath the wires and add solder to the wire itself. That way you know the connection is the best quality and you can visually confirm it is too before moving on.

So now you know how to solder, practice on some wires until you have mastered it and leave me a comment letting me know what you have repaired or installed using soldering.

The products I used in this process are all linked below so you can find them quickly and easily.

If you use soldering on a project your working on, follow me on Instagram or Facebook and send me a picture of your work.

Please leave a comment if you found this helpful, or have used soldering on a project of yours!

You can follow me on Instagram or Facebook as well, send me a picture of your solder work I would love to see it.

-Will

Links to tools and materials used:

disclaimer: all the links below are Amazon Affiliate links. These links support my blog and if you purchase through them (at no extra cost to you) I receive a small commission.

Solder: https://amzn.to/2Rc0ELF

Rosin Flux: http://amzn.to/2bVPzMB

Soldering Iron Electric Cordless: https://amzn.to/36C8aG1

Soldering Iron Gas: https://amzn.to/35Faw5r

Soldering Iron Electric: https://amzn.to/37MWws0

Automatic Strippers: https://amzn.to/2QCjOv5

Dielectric Grease: https://amzn.to/30aPH0U

Rosin Flux: https://amzn.to/37NwKDV

Helping Hands: https://amzn.to/35DqjSk

Heat Shrink Kit: https://amzn.to/2T8AyeL

Heat Gun: https://amzn.to/2QAwHFD