I have a length of 3-pin LEDs that I'm trying to make fit around some corners. I bought the 3-pin 20AWG wire the company has, but it seems so big I can't make solder it well onto the wire - the pair or two are almost impossible to get on without touching. Am I just bad at soldering or do I need smaller wire?
Dan's LED-strip soldering tips, after dozens (hundreds?) of times.
I'm not sure of your technique, but those wires are fine; I've soldered 14AWG on strip before. The secret is to pre-tin both the pads and the wire. Your iron should be about 250C, a bit cooler than many, so as not to melt through the plastic strip before the solder coats. Put the iron on one end of the pad and cram the solder into the joint at a 45 degree angle until it floods the pad. Also, ignore the cut line and cut just past the end of the whole copper pad to get more surface area, which is important not just for eventual strength, but also prevents laminate strip separation whilst soldering.
You bare wire leads are a bit too long too, trim them to 2/3rd the length of the copper pad. Twist them tighter too, to get the wire as cross-sectionally compact as possible, which will help it heat faster and reduce dwell time.
Once you have both pads and leads pre-tinned, lay the wire on top of the pad, and press down with the iron; it will melt both together in 0.5-2 seconds, producing a visible change as it does so; stop right then and blow to cool before it comes apart. Sometime i use a binder clip to hold things together roughly where they should end up after solder. It sometimes helps to bend a dog-leg into the lead so that the wire lays down flat against the bottom instead of having an insulation-thickness gap.
It takes some practice, so use scraps if available. After 5-10 times, it will be old hat; like riding a bike or golfing or making love or whatever; practice.
Some of it is skill. Practice makes better. Steady hands help a lot.
Some of it is using some sort of jig as a "third hand," so you aren't trying to hold things steady and solder at the same time. That can be as simple as weights holding the two pieces in alignment.
Some of it is cutting the exposed copper a bit shorter, so the two pieces of wire can't touch once soldered in place. Bringing the wire in from top and bottom rather than from the end might also help in that regard, if what you are doing allows enough space for that.
In this case I might try the trick of tinning both contacts first, and letting the soldering iron reflow them into connection.
If all else fails, find out if there's a clip-on connector available for that strip's contacts and try soldering to that. Less risk of overheating too.
(There must be an electronics-hobbyist Stack. They've probably discussed soldering techniques many times...)
Forget the advice on how to solder—it's a pain to solder the wires directly to the light strip. The easy button is to simply buy connectors and solder your wire to the leads on the connector. Example: https://www.amazon.com/BTF-LIGHTING-Transparent-Connector-Solderless-Extension/dp/B0B3LZ59FB
I would use some single core from something like a network cable to give 1/2" of space between the led strip contacts and the thicker cable. Then a bit of heat shrink.
All the other information in the other answer about soldering technique etc apply.
Flux is used to make solder stick better, so that you can make tidy joints instead of scrappy blobby messes.
Follow the steps of every how to solder. apply solder to both parts first, and then join them.
Iron too hot is rarely the problem (if the flux is instantly converted into smoke it;s too hot), but the hotter the iron the faster the joint can be completed which means less time for the plastic bits to be damaged
Some sort of clip or weight to hold the wire in position while you heat the joint will probably help.
