SMD Leds better than lightsheet?

erredois · Post by **erredois** » Sat Mar 29, 2008 5:52 pm

I've made some tests with lightsheet but was very disappointed with its weak brightness, useless to me.
It was supposed to be placed in a tight location - Falcon cockpit walls - and I am also trying with optic fibers, with some success.
I am studying another alternative: SMD Leds (Surface Mounted Device). You may have seen them in mobile phone keyboards - if you ever disassembled them.
They're very small, come in various colors including white. But I've seen no modeler using them. Some even talk about shaving regular Leds, maybe because aren't aware of this model.
OR is this some sort of Led that doesn't fit to our purposes? Is there any technical catch that limits its use for us?
Do you have any experience to share?

jwrjr · Post by **jwrjr** » Sat Mar 29, 2008 10:35 pm

I have used smd leds (for the arboretum in the PL refit, among others). Are they better than Lightsheet? For most modelers, no. How many modelers are able to solder on to something that small? Otherwise, they are no different from conventional leds. To get an overall glow, you have to use several of them.

Mr. Engineer · Post by **Mr. Engineer** » Sun Mar 30, 2008 9:51 am

And I would also like to add about viewing angles.

For the SMT LEDs, or any LEDs in particular, their viewing angle is very narrow (an average of 60º?) compared to electroluminescense of about 175º.

So, if you plan on putting SMT LEDs behind the wall, you would need to put a lot more than just three.

And as jwrjr posted, not everyone can solder SMTs. And you would need to get a soldering iron with a different tip.

Kylwell · Post by **Kylwell** » Sun Mar 30, 2008 11:16 am

Sparky has picked up some. The smaller sizes you'll damned near need a microscope to solder wires to them. Very, very tiny.

http://www.samurai-monkey.com/boardz/vi ... .php?t=905

But they are usable.

Sparky · Post by **Sparky** » Tue Apr 08, 2008 1:46 pm

Here's some surface mount LED light strip.
http://www.kc6sye.com/techmages_9_8_07.html

kitty · Post by **kitty** » Fri Apr 25, 2008 10:44 am

Nowadays you can get conductive glues for smd.
That stuf contains metal and once your components are stuck in place , you only heat then up a bit (160 degrees celsius max for 3 seconds at the most) and its done.
I have experimented with some of those glues and they actualy worked.
I applied the glue with an injection needle and used my temp regulated soldering iron at aprox 3 mm distance from the spot that needed to be soldered and it worked.
The problem with smd is that like normal leds, those are tiny chips, but they don't have a thick plastic housing like a normal leds, so they heat up very fast because the heat doesn't dissipate.
Never use the soldering iron directly on the smd component.
also you should put some solder with a low melting temp already on the islands on the circuitboard where the components go before you glue them on.

jwrjr · Post by **jwrjr** » Fri Apr 25, 2008 10:25 pm

Actually, you can directly solder SMD parts if a. your soldering iron tip is small enough, b. your soldering iron is hot enough, and c. you are good enough. A steady hand helps, but that is part of "c". I've been soldering professionally for nearly 30 years, so I will make a claim to "c".
A hot soldering iron is needed so that you can work quickly.