soldering LEDs

[alpinelakespilot2000]

When soldering to the positive terminal of star LED's, do I solder at A or one of the B positions? "A" seems like it is the best option for a bit of a mechanical connection before soldering, but I'm pretty sure I've seen a picture somewhere where someone soldered at one of the "B" positions.

Thanks.



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[Flyguytki]

When I was using the star LEDs the research I had done said that you can use either the a b or solder directly onto the terminal. I chose directly onto the terminals dice I was not having much luck getting the solder to stick to a or b.

-david

[RV8R999]

I just soldered 4 of these this weekend. If you use a good paste flux position B will solder just fine. I chose B to avoid any potential overheating at the terminal - minimal chance if you have the right iron but I didn't want to take a chance.

my .02

[Brantel]

B is the pad designed to solder to.

Some of these LED's depending on who builds them have pre-tinned pads and are much easier to solder to. The ones that are just plain are a pain! Clean the pad real well before soldering might help.

[1911pilot]

Flux is the key here.

I use this stuff all the time at work. One pen has actually lasted me about 3 years now. A little goes a long way, this stuff doesn't make a serious mess like some of the other paste types.

[alpinelakespilot2000]

Originally Posted by 1911pilot

Flux is the key here.

I'm having a really hard time getting the solder to stick to the LED (pads or the actual terminals themselves... I've tried both). It seems like it is b/c I can't get enough heat to make the solder flow to the LED, though it is the same solder iron I use to solder wire to wire at the same temperature. I've tried cleaning the LED good with isopropyl, but no luck.

Would flux do the job here? If so, what is it for, and how to you use it in relation to the iron and solder wire? Can you buy it anywhere other than an electronics store? (Don't have one of those locally.) Is the hardware store variety the same?

Or, do I need some different technique altogether? Thanks for any thoughts.

[1911pilot]

Originally Posted by alpinelakespilot2000

Would flux do the job here? If so, what is it for, and how to you use it in relation to the iron and solder wire? Can you buy it anywhere other than an electronics store? (Don't have one of those locally.) Is the hardware store variety the same?

First off.
DO NOT USE ACID CORE SOLDER/FLUX!!!!!!!!
This is what you find in the plumbing dept. It will most likely work, for awhile, then the acid will corrode everything and make it all fail.Very bad stuff, big mess.

You may be able to find some rosin flux at Lowes in the electrical area if they have soldering irons/solder stuff. Radio shack should have rosin paste flux as well. You should be able to get some good flux wherever you got those leds. (I prefer the pen in the link because its really easy and less messy with no cleanup) Off the top of my head you may also be able to find it at Grainger, or other local electrical supply places.

You should be using rosin core solder, this does contain flux just not very much. Most of the time you do not need to add extra flux but when you need it you really need it. The flux would be applied to the soldering pads (B) where you attach the wires, if I was having problems I'd flux the tinned wires as well. The wires you are attaching to B should be stripped and tinned before attaching them.

Honestly, If the pad (B) and the wire are properly tinned, the iron is running the proper temp and you've got a good tip you shouldn't need extra flux.

Have you dressed the soldering iron tip with a file? This is a common problem, the tip will become "dead" over time and it needs to be cleaned up a bit to promote better heat transfer.

Are you using 60/40 Rosin core lead solder or some type of lead free stuff?

[alpinelakespilot2000]

Thanks for the heads up on the flux. I'll see if I can find rosin flux at my local ACE. Don't have a handy Radio Shack in town even. It just closed a few months ago! If not at ACE, I'll have to make a 50 minute drive or wait for it mail order.

I am using 60/40 rosin core solder, so I should be good there.

Any idea about how long it should take for the pad on the LED to get hot enough to accept solder and at what temperature the iron should be? In the past I've followed the instructions of my EE brother-in-law and done it around 700F for regular wires, but I think the spec sheet for the Luxeon K2's says something about 260C (=500F).

I have tried to keep the solder tip clean, but it could perhaps stand a bit more attention. Will also make sure the wires are tinned well before trying again.

Thanks for the help.

[1911pilot]

I generally run my iron around 650F. It gets turned down for working with touchy components and up when necessary.

The Luxon spec is for the LED itself. You shouldn't have any issues with 700F on the Pads, that's what they are there for.

With everything tinned up and ready to go I'd think it should take less than ten seconds.