Bond wires / SST-40 dedome

I tried doing a combination of shave and hot gas dedome on an SST-40 this evening. I was stupidly in a bit of a rush and ripped off one of the wires (the one by itself). Just for S&G I hit it with the continuity test and the die lit up. Which leaves me with two questions…

  1. will this LED function properly?
  2. I figure two wires are for + and -, but what is the third wire for? It seems like a lot of LEDs have three, I just never thought too much about it

The one on the side (which broke) is, well, was, for electrostatic discharge safety. It should work without it just as nice.

Nice, what are you a surgeon? Nice blade work! :+1:

Haha, thanks KB. I sliced as close as I dared (with a blade for a safety razor), then dunked in boiling gas for 15 minutes to loosen the remaining dome from there phosphor, followed by another trim with the razor to clean things up.

I can’t wait to get this into my L2 host with Mtn FET+1 driver. Should be pretty sweet.

That is actually brilliant, that bit of silicone protecting/supporting the bond wires!

Now can you do 5-6-10 more like that, send me your pay-pal address! :wink: :+1:

Yeah lets us know how it looks, wonder if it will show up in the beam a bit?

You have been lucky it was the “unnecessary” wire. What is the throw and lumen output after dedoming?

Haven’t had a chance to assemble the light yet, had to go back to “real life” for a while (taking care of my 4 kids). Play time will come soon enough though :wink:

That is one clean shave. Nice work gchart. :+1:

Question for the OP. Are you using the FET + 7135 Driver - 17mm - MTN-17DDm Product Code: MTN17DDm-NUV? This is my favorit driver, but being direct drive for high mode that would make it capable of delivering 10amps. This led is only good to 9.5amps.

Yup, the one and the same. The LED can handle the amps, but it may be beyond the optimum range. I haven’t had a problem with it, but you could always use weaker cells to limit the amperage.

Edit: well, since I was working with a Convoy L2 (updated model) technically I used the 20mm version but it’s the same components just on a bigger board.

I have an L2 with an SST40 with dome and I’m curious about your numbers with dedomed version.

Great question, but I dunno really. I have a meter now, but it’s still sitting in the packaging. And I sold that L2 at Christmas, so I can’t measure it now. But I have the parts on my shelf to assemble two more just like it. Hopefully I’ll be able to build & measure them soon.

I have some SST40 leds so maybe I will try the slice and polish dedome method and try it in mine.

Good luck, let us know how it goes

My friend has 8000 grit sandpaper. I will borrow some from him. :slight_smile:

Side note: polishing the dome remnants after slicing it can or will ruin the underlying bond wires.

Cheers :-)

The SST40 survived well. but the SST20 leds died.

Problem is that rubbing the sliced dome against sandpaper rustles the underlying bond wires. I can see the effect with my bare eyes. Did it to a 5000K XHP50A, the bond wires got all messed up and it just died. On another 4000K XHP50A did it more gently, but still something went wrong and upon heating up half the dies started turning off, an indication of certain damage to some bond wires.

It is just not worth it, just shim the emitter properly and cut the dome at two (180°) or three (120°C) different angles, just that. Do not worry if it doesn't looks perfectly flat, the emitter will work well. Polish it, and you take an unnecessary risk. Of course, you can also try to polish it very slowly and gently. Good luck in any case. :-)

Cheers ^:)