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Hand wiring up smd led's

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For an application I want to do it is out of the question to use pcb as I need to minimize the footprint of the circuit as much as possible. It consists of just led's and wires(the drivers are a different store).

The link gives the led's I probably will use but these things are very small. I need to attach wires to each of the LED's(I have done this using magnet wire but it won't work well because it is too big(I think 26 gauge).

I need to run 6(or potentially just 3 if I have to) in series which gives

18+1 wires. Each led will consume max 25mA and therefor the ground must carry 18*25 ~= 1/2 amp. I can use the 24 gauge for that but need much smaller "hair like" wire for the anode connections.

The biggest bitch about it is going to be wiring up 24 groups of these ;/ I can't see how to prevent the wires from breaking off the led's. (I already screwed up the pads on one trying to get the 24-gauge wire solidered on... it's almost bigger than the led itself ;/)

I figure with thinner wire it will be easier to solder(maybe make a jig or something somehow to hold the wires down) but the wires will break easier(Although they are more flexible).

What I am doing is drilling one in the surface plane of a piece of wood that will carry the wires and holes into the wood to hold the led's. I need to minimize as much damage to the wood as possible(hence the small led's and wires only).

I'm thinking that by using 32-gauge magnet wire I might be able to at least get somewhere but I've not worked with such small wire before. And chances are I'll need something even smaller ;/ Also each I'll be PWM each led which may or may not matter.

Any ideas?

Thanks, Jon

Reply to
Jon Slaughter
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I found some hair thin wire and was able to get it working... actually the hardest part was getting the cathods all wired up using the 24 guage wire. Supprisingly the "hair wire" (I think it's like 40 gauge(about 3-5 mills thick) sticks pretty well.

Is there any way to remove the enamel coating quickly and easily? Right now I'm scraping it off but I need a better way.

Reply to
Jon Slaughter

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Have you considered ditching the discrete LED's and just go with fiber optic cable? That would seem to be a lot easier that the approach you are considering.

-mpm

Reply to
mpm

Buy some wire with insulation that's designed to be burnt off by soldering temperatures. I think you need an 800F iron, not

600F, but it'll save trouble - scraping will introduce thinner or weaker spots in the wire and it's more likely to break there in future.
Reply to
Clifford Heath

If can be bare wire just strip off some ac line cord and separate out the strands...

Reply to
Eric

Why wood and wires? Get a piece of copperclad FR4, score patterns with an X-acto knife, scrub hard with Scotchbrite, solder them down.

John

Reply to
John Larkin

We have a winner. You can pick up a full color fiber optic "plant" thingy for 1$ that has RGB LEDs, a bunch of fiber and of course a chip driving the whole thing with different colors.

Reply to
a7yvm109gf5d1

Well, it was just for testing... I'm not sure being burnt is a good idea as it might end up burning off too much? I actually need very little exposed area... probably less than 1 mm.. so it might work.

Reply to
Jon Slaughter

Because I said so... It's the application. Can I make a pcb 2mm thick that contains all the circuitry? In fact that would be the easiest way but I'd have to put 18 traces in 2 mm + the large ground wire + vias and it's not going to work. Although it does more descruction to the wood than I'd like it would definitely be easier to "install" and "replace".

Reply to
Jon Slaughter

No, it can't.

I actually ripped up an old guitar pic I had that uses, I guess, 40gauge wire and it works pretty well. Although maybe too small it actually solders to the led pretty easily and holds decently. The enamel is copper color so it's hard to tell if it's bare(actually almost impossible) but it seems to come off easy too. (although I'd rather have a chemical method)

Reply to
Jon Slaughter

Have you considered ditching the discrete LED's and just go with fiber optic cable? That would seem to be a lot easier that the approach you are considering.

-mpm

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I don't think this will work? Can fiber optic be let than 20 mils in diameter? (remember, because of the design I have to "stack" around 18 together.... my hole need to be small as possible. Not only that the fiber would need to make 90 degree bends. I'd still have to drive the fiber with RGB LED's to get the same effect? Hence they would have to exist somewhere else and just as many... so the fiber seems to be an aditional cost. Although if it solved the routing problem it might be worth it as one could just make a pcb with all the led's on it. I don't think though that it will work though because of the specific application. I don't have much experience with fiber optic though and maybe it is flexible and thin enough.

After playing around with it and the very thin wire I think it might work well. The biggest problem I'm coming up against right now is that the cathodes for all the led's are split so when I try to solder them all at once to the ground wire one usually end's up not making it.

Reply to
Jon Slaughter

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" Is there any way to remove the enamel coating quickly and easily? Right now I'm scraping it off but I need a better way."

I just burn it off with a small butane torch and then lightly sand before tinning. I've used chemical stripper in the past but it's nasty stuff. Methylene Choloride and such...

George Herold

Reply to
ggherold

FR4 is usually 0.062" (1.6mm) thick, but it's also available in 0.032" (0.8mm). If that's still too thick, why not apply copper tape directly to your wood. Then use an X-acto knife to make patterns as was suggested earlier? You could use the copper tape for your ground, or use paper thin brass or copper sheets from a hobby shop. I bought wide adhesive-backed copper tape at a garden center. It's sold to repel slugs (snails).

-Dave Pollum

Reply to
x

" Is there any way to remove the enamel coating quickly and easily? Right now I'm scraping it off but I need a better way."

I just burn it off with a small butane torch and then lightly sand before tinning. I've used chemical stripper in the past but it's nasty stuff. Methylene Choloride and such... ====

I can't get the precision I need. If I used a torch I'd end up burning way to much off. I just need to get about 1mm or even less. These wires are hair thin... I think your thinking of a much larger gauge?

Reply to
Jon Slaughter

It's not thickness but width

it would be about 3mm x 3" x h

where h is the "thickness" you refer too.. it can be up to several mm but the smaller the better.

Reply to
Jon Slaughter

What part of "designed to be burnt off" don't you understand? There are at least two common types of insulation for this.

Reply to
Clifford Heath

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Labor costs will kill you on hand-assembly of whatever this is.

If fiber optic is out (why is that again?), how about using a membrane keypad / overlay with integrated LED's? Like these:

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Reply to
mpm

Anything done by hand will kill a project. ( other then a one off )

If this is a funded project, why not use a FLEX circuit.

A large panel can be created and can have as many rows as you want, then cut down with a pair of scissors.

And you can use standard PCB software.

donald

Reply to
donald

Hi Jon,

Looking at a Flex circuit for this looks pretty easy.

You said: >I need to run 6(or potentially just 3 if I have to) in series which gives >18+1 wires. Each led will consume max 25mA and therefor the ground must >carry 18*25 ~= 1/2 amp.

Does series mean all the red leds, all the green leds and all the blue leds in series with each other ?

And a common ground ??

Well thats 4 lines, right ?

To have 18+1 wires are parallel, right ?

If each led is driven separately, then any one trace will have 25mA, except ground as you stated.

I think this can help you:

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Page 13 is what you need to look at.

I have not used this company.

donald

Reply to
donald

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Page 14 says an 8 mil trace of 1 oz copper will carry .5 amp.

donald

Reply to
donald

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