How to Solder a Wire to a circuit board or connector? ANSWERED

The art of gluing metals dates back to the ancient Egyptian goldsmiths. However, Ernst Sachs first introduced a mass-produced electric soldering iron only in 1921.

Today, the soldering iron is a staple in many industries, including electric works, jewelry making, and mosaic art.


You’ll need a soldering iron to start soldering wires yourself. You’ll be able to save a bunch of wires by crafting connections that will last a lifetime. It is possible to solder without a soldering iron though.

This article will teach you how to solder a wire like professionals. We’ll also list the tools and safety precautions to take for a smooth soldering job.

How to Solder Wires Together? Summary

You can start soldering wires by splicing and twisting them. Next, using a soldering iron, apply rosin flux followed by leaded solder on the welded wires. Finally, seal the connection with silicone paste before heating a heat-shrink tubing on the connection with a heat gun.

Soldering produces some fumes, so you’ll have to ensure safety by wearing goggles and a mask, besides opening the windows for natural ventilation. Additionally, it’s better to place a non-flammable surface on the workbench to catch molten solder spills.

Purchase Soldering Tools

It might be better to borrow the tools if you’re doing a one-time soldering job. However, if you’re expecting regular soldering work, investing around $100 in a long-lasting handful of tools is better. Here’s what you need to make a neat wire connection:

-Soldering gun

-Rosin Flux

-Small brush

-Leaded solder

-Silicone paste

-Heat-shrink tubing

-Alligator clips

-Place Heat-Shrink Tubing

You’ll often have to place the heat-shrink tubing before soldering the wire. First, try the tubing on your wire and ensure it’s well-fitted. Otherwise, you might find it difficult to completely secure the splice with a loose shrink tubing.

Additionally, make sure to cut a generous tubing portion to cover part of the insulated wire on both sides of the splice. One more tip: keep the shrink tubing at least one foot far from the soldering work to prevent it from shrinking before you fit it on the splice.

Splice and Twist Wire Ends

To solder two wires together, start by exposing an inch from both wire ends. Then, you can use store-bought wire strippers or a utility knife to remove the insulation.

Next, you need to form a strong bond between the exposed ends. We recommend you fray the wires and intermingle the fine “fingers” to create a mesh.

Then, twist the sides, bringing everything into a tight and firm connection. This is the neatest method that ensures the soldered part blends with the rest of the wire.

Apply Rosin Flux

Let’s break down that fancy term.

Flux facilitates the solder by clearing the oxides formed on unprotected wire metal. Interestingly, different flux types are determined by their base material component.

This brings us to rosin, which is one of the most common flux variants in the market. It’s primarily composed of a pine tree sap extract, in addition to some acidic activators. This composition will aid the soldering process, and further protect the metal against corrosion.

For application, use two alligator clips, jaws facing up, to hang both wires above your working surface.

Now, use a small brush to evenly cover the wires with a thin flux layer. Next, use a preheated soldering iron to heat the wires until the rosin flux melts and seeps between the mesh. Wait for a few minutes to let it cool before applying solder.

Apply Solder

Whether you go lead-based or lead-free, the solder metal alloy will permanently fuse the spliced wires. Those alloys have a lower melting point than the joined metals, so you needn’t worry about damaging your wires.

For electrical applications, solder alloys are typically sold as thin wire spools available in different thicknesses. Regardless of what you choose, make sure not to buy plumbing solder, which is generally much thicker.

Before application, put on your safety goggles and mask to avoid lead toxicity and any harmful fumes. Then, start by tinning the soldering iron to prevent its oxidation and ensure even heating. Simply hold the solder to the soldering iron tip until the iron gets a coat of solder metal.

To apply solder to spliced wires, use your soldering iron to heat the joint from underneath while holding the solder metal above. Keep holding the iron while moving the solder tip to cover the wires evenly. Finally, let it cool for a few moments before applying silicone paste.

Apply Silicone Paste

You might know silicone paste by other names like silicone grease or dielectric grease. It’s a white viscous combination of silicone oil and a thickener.

We recommend applying silicone paste after soldering the wire to waterproof it and protect it against weather-related damage. Use your small brush again to evenly coat the soldered wires with a small amount of silicone.

Secure Heat-Shrink Tubing in Place

Finally, cover the soldered connection with the heat-shrink tubing you placed in the first step. The tubing will brush out some silicone paste, which you can simply wipe out with a cloth before heating the tubing.

Make sure you center the tubing to cover the insulated wires around the gap, as it will shrink by around 10 percent. Then, secure the shrink tubing by heating it from the middle to the ends. This method will further squeeze out excess silicone.

You can heat the shrink tubing using a heat gun, lighter, or hairdryer. If you’re using a heat gun, you’ll have to set it at the lowest setting. Conversely, you should set a hairdryer at the highest setting to achieve similar results. Be aware that a lighter won’t shrink the tubing as evenly.

Wrap Up

Let’s recap how to solder wires together.

First, slide the heat-shrink tubing inside one wire before exposing and bonding both wires ends. Next, apply rosin flux, heat it, and use the soldering iron to fuse the wires together with solder alloy.

Finally, brush the connection with silicone paste and securely seal by heating the shrink-tubing in place.