Soldering DIY LEDs

[Velodog2]

Anyone have tips for doing this? Those metal stars they are mounted on are intentionally good heat sinks and I struggle to get the joint up to temp. When I do the whole star is too hot to touch and I worry about damaging the chip. And then the joint ends up looking like crap cuz it was never really hot enough.

 

[cparka23]

What iron and tip are you using? The wattage and shape of the iron tip is very important to getting a good solder joint. The iron really should be at least 40W. For soldering onto pads, I use a chisel tip that is a little more than half the width of the pad. Trying to do this with a pencil tip will be a huge waste of time. Some people will make it work, but they might just not know any better.

Also, use flux to prepare the pads and wire beforehand. Exposed metal surfaces oxidize over time, which makes solder not stick. Additionally, heat oxides these surfaces, so a hot soldering iron on a surface w/o flux tends to make it worse. Flux will clean the surface and protect it from oxidation. A single drop of flux is probably good for at least 4 pads, so use a tiny amount. Put some on the pad, then touch the hot iron to the pad to melt it away. Now you're ready to solder. (Flux comes as liquids or pastes. Don't matter which you use, but get the "no clean" variety if specified. It means you won't have to remove the residue later.)

 

[Velodog2]

Ah thank you! I'm obviously not experienced at this. My iron is only 25 w. But I do have a chisel tip I can try and flux as well. I will do those things and if that doesn't help enough look for a higher power iron. I guess getting the LED and its little lens that hot doesn't hurt it.

 

[cparka23]

The LED and lens can withstand a little heat, but you still don't want them to get too hot. The way you do that is to get the solder to stick to the pad quickly. If you have to heat the pad for a very long time to get the solder to stick, the rest of the star has time to heat up as well. A hot iron and the fluxed surface makes the process fast, thus safer for the electronics.

Give it a try with the 25W iron and see if it'll work. The flux should help a lot, since a little flux residue left on the pad helps the solder to liquify more easily. Lower wattage irons can get just as hot, but they don't have the power to keep their temperature from dropping while soldering. You might have to wait between touches to allow the iron to reheat.

 

[Velodog2]

Ok so this worked so amazingly well it's hard to believe. Making the joints was nearly instant in some cases. Thank u for some incredibly useful info!

 

[cparka23]

Glad to hear that it worked, and it's pretty cool that you were able to do it with the 25W iron, too. It's hard to believe how much flux helps.

Best of luck with the rest of your build! Post some pics when you're done.

 

[Velodog2]

I upgraded the little 8 watt led fixture that came w the Nuvo 8 we got a few months ago.

 

[TJ's Reef]

Very nice work and FLUX is definitely your friend on DIY LED projects. I end up always pre-tinning all stars and wires before hand so its quick and easy once you get to the actual permanent soldering. I have a 108 emitters on my DIY array, was a lot of tedious work with the iron.

Cheers, Todd