Step 3: Soldering wire

Picture of Soldering wire
I started soldering just two pieces of wire together because it's the most forgiving way to learn. You can't really get the wires too hot - the insulation might start to melt a bit, but you're not going to hurt the wire.

With the wires you want to join twisted together and held in place, pick up your soldering iron in one hand and your solder in the other.

Touch the tip of the soldering iron to the wires and keep it there.

The wires will begin to heat up. At some point over the next 2-10 seconds (depending on how hot your iron is) the wires will be hot enough to melt the solder. You can touch the solder to the wires (not to the tip of the iron!) periodically to see if it's hot enough. It's tempting to just touch the solder to the tip of the iron and melt it right away, but don't! You will end up making what's called a cold solder joint. This occurs when you melt the solder around the joint, but you aren't melting the solder into your joint or onto your components to make a good connection. It's much better to wait the few seconds and melt the solder onto the hot wire itself.

If you touch the solder to the wire and it begins to smoke and melt, the wires are hot enough. Add the tip of your solder to the joint as necessary. You want to introduce enough solder to cover the wires, but not so much that you create a big glob of solder at the bottom of the joint.

Once you've got what you think is enough solder on the joint, pull the solder away and then remove the soldering iron. If you're using a gun style soldering iron like I was, release the trigger to turn it off. If you're using the kind that doesn't have a trigger the iron will stay hot, so just place it back into the holder.

Here is a video of wire being soldered. The whole process happens pretty fast, and isn't nearly as complicated as you may have expected.

Here is a close-up video of the same process.

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oneoff3 months ago

Thanks for the guide! I also wouldn't recommend stripping wire using teeth. Some plastic wire insulation can contain lead. Here's a CDC account of someone getting lead poisoning from chewing the plastic:

woodswalker6 years ago
I bought a 30W soldering iron from Radio Shack. I'm having a lot of trouble because it takes as long as 90-120 seconds for the solder to heat up. And if I don't touch the solder directly to the iron, it never gets hot enough at all. Plus, the solder doesn't flow well and it turns into balls & blobs. I'm puzzled. What's wrong?
I know this is an old post, but someone may benefit.
There's a few possible problems, the obvious one is you're iron isn't hot enough. I prefer a 40W iron over a 30W any day. It seems 30W are the most common, but they just don't cut it for me.
Try a cheapo model form ebay etc for $5 or so and see how it works for you.
Another fix is to heat the iron up a bit with a torch. I rarely need to do this to boost heat, but I will use a torch as the heat source for the iron if I'm too far from an outlet..

The other problem could be thinking the flux inside the solder is enough. It is not.... At least it has never been for me. You need to flux the surfaces and be sure the surface can be soldered in the first place.
The surface could be coated or plated with something that either the solder or the flux doesn't like. It might also be corrosion, a lubricant, protectant, or who knows what. In those cases I clean it with a chemical such as electric contact cleaner aka brake cleaner, or even carb cleaner, but most people use alcohol. If that doesn't work then it's probably some kind of coating you'll need to remove with force, like sandpaper or a Dremel tool to break thru to the good metal. Once you've ground the bad part off, clean it, coat it with flux and try again.
If it's still being difficult you can try using sandpaper on it while it's coated in flux. I like 320-400 wet/dry paper, maybe 180-220 if it's really bad. Cut a small piece for sacrifice because you don't want to use it again now that it has flux on it. After you have either roughed it up nicely, or ground thru the problem coating whatever it was, clean it, flux it, and try again.
I prefer to coat the problem item in solder first, that way I know it'll work when it's time to attach something. Assuming the iron is hot, clean, and will hold solder (plain old rosin core 60/40 works best for me), put a little on the tip, then apply it to the surface and hold until it flows and coats your surface. If it's a large item and you can't get it hot enough you will need to preheat the item with a torch or whatever, I've used anything from little butane torches to my oven, as long as everything can handle the heat that is. (fyi; preheating also works for welding when the machine can't generate enough heat). Once it's hot enough the solder will flow nicely into the area worked on, and your problem is solved.

If you never could get the solder to stick then you might be working with the wrong metal, like aluminum, so use the appropriate method for that metal, or simply try using a screw or bolt as a contact. If you can figure out what the base metal is, then search the net for a bolt material that will not react with it. Example; drill a hole and use an appropriate bolt/nut and torque it down good, then apply solder to the bolt's head which should be a snap. Common steel bolts are usually coated with something which probably needs to be ground off. Grind off just enough area for what you need, and preferably solder it in a way you can still use the tool to remove it if needed. Now flux your spot and apply a little drop of solder like described above. Being a bolt it's probably heavier and may need a little boost with a torch.
I flux/solder each piece first so I know they're both good to go, then I put them together and add a drop of solder with the iron until it flows.

I hope this helps some people with their soldering problems...


I would probably avoid using brake cleaner then applying heat, because depending on the formulation you can emit phosgene gas:

Thanks, something to think about. I don't think you can buy that kind of brake cleaner anymore, plus it evaporates almost instantly when cleaning stuff like that. I do remember spraying the older stuff on something red hot and the smell was horrible. Not sure if it was that particular gas, but omg it was bad!

Speaking of solder, I lost my old solder and flux in a move so I bought this new solder and flux, some "safer" crap or some bs but it was all I could find. I haven't been able to solder anything but clean copper wire and that barely sticks together and often fails. It's horrible stuff. Maybe that was the original posters problem? I guess I'll have to buy some from china on ebay or something.

If you have a old/not very good soldering iron and are having trouble getting the solder to melt by touching it to the component, you can touch the solder directly to the iron and make a "cold solder joint", but after it's on the wire, keep your iron there until you see the solder fill the cracks. This can work because when you touch your sodlering iron directly to your component, hea tis being conducted through a verysmall area, but if solder is completely covering your componenet and you heat up the solder, the componenet will heat up much faster.

actionjksn4 years ago
I don't have a heat gun, so I always use a Bic lighter. I have used it dozens of times and it works perfectly. You just hold it under the heat shrink tubing for a couple of seconds, and it shrinks around the wire nicely. For solder, the thin stuff works best for electrical work. I bought some Kester brand 60-40 alloy 0.31 inch - 0.79 cm diameter. Also for electrical work you are not supposed to use acid core solder, or it will erode your components. You should use rosin core only. The ones that look like a gun are not for electrical components, they will run electric current through your components, which can fry them. You should use the ones that you hold like a pencil. The gun style would be Good for wires though I taught myself, but I was already experienced at sweating copper pipe, so I already knew to heat the piece instead of the solder. My first project was the coax connector on my TV, which had broken off. I found my high quality solder at a hobby shop. I got my soldering iron at Radio Shack. I didn't buy the cheapest one they had, nor did I get the most expensive one. It has lasted me since 2000. But I don't use it every day either, It's a 40 watt..I want to get the one with a separate transformer, with an adjustment knob. Microcenter has some good deals on them, if you live near one.
Bradlez926 years ago
should i be worried about the exposed wire i just soldered? you know, after im finished with the components, and all is said and done with soldering the wire and building whatever im building, should i be worried about the exposed wire?
Get some sort of heat shrink tubing. basically, if you take a hairdryer (or your soldering iron) and heat up the tubing, it will shrink tightly around the joint you just made, allowing you to seal up the bare wires. (make sure to wait till the solder is cool, you don't want to melt the plastic as it shrinks)
wai tbut if the solder is cool, then how will sit HEAT shrink? and i could probebly get the iron and solder at hobby stores right?
You could go to a hobby store, any electronics shop, like a Radio Shack would have them (just be weary of price, and I would NOT recommend those "cold touch" irons. In my opinion, they aren't as effective.) As for the shrinking of the tubing, once the solder is cooled, you use heat from the soldering iron (at a distance) (or personally, I use a hairdryer because its a bit more directional) and it will shrink to fit the joint that you have just soldered. You are shrinking it, not letting it shrink on its own.
cool thanks for the "cool touch" advice the hair dryer sounds like a better idea anyway
Bradlez926 years ago
like shouldnt there be some sort of protectective incasing, or electrical tabe to protect the exposed wire from the elements?
Sarkazmo6 years ago
Also, it should be noted (if it hasn't already,) that you should not move the join being soldered until the solder has solidified (a few seconds) so as to not cause a cold solder joint that can cause resistance in the electrical connection and can cause the joint to fail and actually come apart.