How to solder wires to connectors

This article is specifically for how to solder wires to connectors. If you are new to soldering or want to know about general soldering I have a more suitable learning how to solder a beginners guide here.

Also if you are new to soldering be aware that soldering produces smoke and fumes that can be harmful.

Check out my article on solder fume extractors and air purifiers. These will help to reduce what you breathe in.

You may find a helping hand useful for this task. By helping hand I mean the device, not a friend to help but if you have one around they could also prove useful.

The advantage a helping hand has over that of a friend is that they hold things completely still and don’t scream when things get hot as my friend did. The biggest problem of how to solder wires to connectors is movement. When everything is held still and in place, the rest is relatively easy.

If you’re looking for a helping hand or anything else here to make the job easier check out my article on soldering iron accessories and tools.

If you don’t know what a helping hand is it’s the thing above with the crocodile clips.

You need to have the correct tools for the job. If you need a soldering iron see my guide on soldering irons here.

Perhaps you need a soldering station instead, if so check out my guide on soldering stations here.

If you look at soldering a lead to a jack plug you will learn a few of the techniques of how to solder wires to connectors. You will also find a bigger tip will make the soldering job easier.

How to solder wires to connectors – Turn up the temperature

If you have a soldering station as opposed to a soldering iron you will probably find the job easier if you turn up the temperature by a few degrees.

Strip the cable PROPERLY!

The task of stripping the cable may also cause a few problems if you’ve never done it before. Depending on the thickness of the cable it may be easier to use a sharp knife to take off the plastic insulation rather than a cable stripping machine.

I lightly score around the circumference of the cable where I want it stripping to. You have to be careful not to go through to the copper shield under the plastic. Then lightly score from this line along the length of the cable to the end. You should use more pressure as you get to the end until you cut through the plastic.

Then pull apart the two ends of the plastic. This should separate along and pull off as you get to the circumference score.

Under this will be the shield. This will usually be woven so you should unravel it with the tip of a small screwdriver to reveal the insulated core in the middle. You don’t need to take this back too far, in fact, the less you take back, the better the screening properties of the completed lead will be. Just reveal enough so you can strip off some insulation off the middle core.

Twist the strands together and tin the end. Twist the unravelled screen and tin the end of that.

For more information about stripping wires read here.

How to solder wires to connectors – Essential tools

Now comes the helping hand. Use one part of it to hold the unscrewed jack plug. Don’t forget to put the other end of the plug over the stripped cable. It’s not a good feeling to complete a perfectly good soldering job only to have to unsolder it because you forgot to put the other half of the plug on!

On a serious note, If you do need to unsolder it, be sure to have a look at my desoldering tips guide.

Use flux to help the solder flow

Hold the cable with the other half and position the shield and core wires of the cable to the respective connections. I solder the shield connection first.

I apply the soldering iron tip and the solder to the metal tag near to where the tinned sleeve wire touches it and gradually introduce more solder until the molten blob touches the cable and melts.

Then take the iron away and don’t touch anything. It can take a good ten seconds for everything to set and cool. If you move anything too soon you’ll ruin a perfectly good joint.

You need to apply the heat to the metal part on the plug because that takes the longest to heat and melt the solder. If you did the cable and the tag at the same time, by the time the solder properly melted the wire insulation would have started to melt.

The core can be soldered in the same way. This has a smaller metal area so won’t need as long to melt the solder. This time I usually put the wire through the hole in the tag and bend it slightly inwards. That way the joint won’t touch the screw on the body of the plug.

Sometimes there’s a plastic transparent PVC sleeve that slides over the join. This is to stop it shorting on the body if it’s metal. After years of trial and error, this is the best way I have found of how to solder wires to connectors of the jack variety. These techniques can be adapted to solder connectors of most types.

How to solder banana plugs

Soldering banana plugs is easier than a two-connection audio 3.5mm or 1/4″ plug. There’s only one connection and you don’t have a screened cable to strip. Strip and tin the cable and use the helping hand to hold the wire while you tin it.

You can see from the picture the back of the banana plug is just half cylinder. I don’t bother to tin this. It’s already bright and clean and you end up filling it with solder and that’s where the cable needs to be.

Just use the helping hand to hold the wire in the half-cylinder back of the banana plug. It’s then just a simple job of heating up the back of the banana plug while applying the solder. The helping hand keeps everything still while it cools. You then have the perfect solder joint.

Soldering a banana socket

Remove the plastic by unscrewing the nut on the back, then you won’t melt it.

Use a helping hand to hold the tinned wire in place and again it makes it a simple soldering job.

The same can be done with a spade connector.

The same here with an IEC mains socket. As you can see from the picture you get a better solder joint if you have the cable along the terminal and not through the hole. Doing it this way means the cable has more contact space with the terminal. It makes for a cleaner joint and makes it easier to slide the heat shrink-sleeving over the joint.

How to solder wires to connectors – Final thoughts

The one thing here to notice is how much easier it is to solder most kinds of plugs, sockets and terminals with a helping hand. You have everything held in place without moving it while you make the joint and while it cools down.

I’ve tried the various methods of trying to hold it myself while soldering and I won’t be going back to them.

The other main take on soldering larger objects is to get the soldering temperature right and use extra flux as the extra heat you need means the flux in the solder core can evaporate before its done its job.