While making Ghost Patrol and our next game, CarTuners, I've wound up soldering a number of LED strips. I've heard other people complaining about how big a hassle this is, and when I started, that's how I felt too. It felt like I needed to hold the LED strip, the solder, the soldering iron, and the wires, all with just two hands! But I've since developed a few tricks to make it a lot easier. In this post I'll walk through my process.
Tools & Parts
For this process I use:
An LED strip
Wire strippers (for the individual wires)
Wire strippers (for the cable jacket)
A mediocre 3d-printed solder holder
All of these items come from innumerable manufacturers in many varieties - most of which will work great. You can absolutely use the same wire strippers for the jacket and the individual wires, though the Knipex ones don't work well for stripping very short lengths of wires but are kind of magical at the tasks they're good at. Lead-free solder is better for environmental and safety reasons, and once I have finished my current spool of leaded solder I'll try switching, but I linked to what I'm using.
Remove the Environmental Protection
The strip I'll be using here is coated with silicone, to protect against dust, etc. I use these in places where players might handle them. The downside is the protective layer also provides thermal insulation, and over the years I have had to replace some such strips because individual LEDs have burnt out. For this reason, I only use silicone-coated LEDs when I have a good reason to. Otherwise I can just skip this whole step and need fewer repairs down the road.
To prepare a silicone protected strip, first cut through the silicone, but not all the way. My goal here is to cut just deep enough so that I can peel the silicone away from the flexible printed circuit board (flex PCB) and tear it off where I'd scored it. When I used to cut all the way through, I found I would often damage the PCB. Sometimes this manifested as an immediate failure, but even worse is when they didn't fail for a month or two. It's always easiest to troubleshoot problems right after creating them.
Strip and Tin the Wires
Of course you'll need to strip the insulation. I usually cut away 10mm of the wire jacket, and then a bit over a millimeter of insulation from each wire. Since I'm using 4-conductor cable, I also cut the 4th wire back to the jacket. Then I tin the ends of the wires (this means covering them with solder). For the solder to flow onto the wires well, the wires need to be hotter than the melting point of the solder. I try to hold the soldering iron against the wire to heat it, and then conduct heat through the wire to melt the solder.
Tin the LED Strip Pads
Similarly it's easier to heat up the pads of the PCB enough for good solder flow when there's no wires in the way. For this and the next step I use a magnet to hold the LED strip in place. A friend says she uses a block with a rubber band for the same effect. The goal is to free my hands for the solder and the soldering iron. As before, I am heating the solder pads on the circuitboard, then using those to melt the solder.
Solder the Wire to the Strip
Now that the LED strip is held down with a strong magnet or rubber band, and both the LED strip and the wire have a healthy amount of solder on them, all we need to hold is the wire (via pliers) and the soldering iron! It is important that the solder on both the wire and the board melt, so they can flow together and make a solid electrical and mechanical connection.
Inspect it
Take a look if there's any big globs of solder that might be connecting two wires. If there are you can probably brush them away with the hot soldering iron. For silicone-coated LED strips I usually "replace" the silicone I trimmed away with hot glue, for electrical insulation and mechanical strain relief. Ideally I would test the LED strip before doing that, but it's rare that I remember, so if something goes wrong I usually have to scrape the glue off before I can fix it.
Done!
After that, the LED strip is ready to install in your project!
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