A Perfect Dedome?

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AlexGT
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Sirius9 wrote:
I thought it was a reverse polarity protection! !{width:70%}https://s6.postimg.org/ms33f318h/SST-40-2.jpg!

Sirius, that has got to be one of the cleanest dedomes I have seen, Good job! Thumbs Up

What did you use to dedome and what steps did you follow?

Sirius9
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It’s not that clean as it seems, I was actually not impressed with this results at all, small white-ish dots that you can see on the led surface, that’s actually silicone that I was not able to clean off.
I am using stuff that is not available in US, it is called medical gasoline, super pure gasoline that can be used for cleaning wounds (evaporates fast, doesn’t leave any smell afterwards), It gives perfect results with XML/2 and expecially XPL leds, XPG2 also end up looking nicely, XPE2 leds are a bit stubborn thou.
For example XPL is dedomed in about 15-20 minutes in this stuff at ~50 degrees celsius.
Tried my luck with 2 leds, first one with hot dedome, left it in until I noticed dome swelling (maybe temperature was too high).here are the results, as you can see phosphor layer was also affected, piece fell of with the silicone while I was attempting to clean silicone that was left stuck to the led surface. The second one was cold dedome.

I left the led in for about day or two, I was not expecting good results because stuff I use affects on a tint shift so I usually leave led in just until I notice that dome started lifting from led’s surface, so shortest possible time, after that I rinse it thoroughly with 96% alcohol, blow off with compressed air then rinse it with distilled water one more time -> drying with compressed air and that is it, led i ready to be installed.

When I dedome XPL led I noticed that dome is not swelling its as if the “dedoming liquid” gets between transparent silicone dome and led + white silicone that surrounds leds die and just lifts the dome, results are perfect, as if CREE never put the dome on. Dome on the SST-40 behaves differently.

 

EagleShield
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I don’t think that medical gasoline is used to cleaning wounds.
The medical gasoline we have here is for removing the glue from the skin when removing the plaster (right word? Patch?) from small wounds. Or cleaning the microscope lens from immersion oil.

Same product?

CAS-nr.: 64742-49-0

Substance Name: Naphtha (petroleum), hydrotreated light
Or Benzinum medicinale

.

Sirius9
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Quite possible, I would say that I pretty much had good luck with major injuries, I didn’t have any, so didn’t actually see this stuff in its intended use, It can only be bought in pharmacy and it is not for drinking so, I presumed it was for cleaning Big Smile

 

Barkuti
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The SST-40 works without the substrate wire, at least it lights up with my Big Smile multimeter. Must be nothing major.

The dedome hasn't come off as easy as with XM-L2s, its dome seems tougher. The die looks dedomed but apparently there's still like a layer of “something” over there, I'll take another close up peek at it tomorrow.

By the way, one of my latest dedomed cool white XM-L2s (from a modded TA13) shows up a pretty nice yellowish tint, cool! White spirit may need heat with tougher domes, but I believe it doesn't alters the phosphor layer (no tint shift). A dedomed XM-L2 from an UltraFire XM-L2 turned out bluish, while another previous XM-L2 from the same torch model… Facepalm kermity.

 

Cheers Smile

The_Driver
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What is the current consensus on de-doming of the Nichia 219C? Mem managed to do it chemically. He was using some kind of solvent and probably gasoline. Did he get more specific? Has anybody else managed to do it?

Agro
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According to Saabluster, gasoline leaves a residue on dies…

-X3-
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I’ve sliced mines in my D4, it does improve throw.
I used a razor blade, with a drop of oil. I sliced the dome, then another slice, and a last one to be as close as possible from the phosphorous surface

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The_Driver
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Agro wrote:
According to Saabluster, gasoline leaves a residue on dies…

That is certainly possible:
https://www.quora.com/When-regular-gasoline-evaporates-does-it-leave-beh...

I would prefer to use chemicals because I want to dedome 12 219Cs on the PCB of a Noctigon Meteor. There is not a lot of room and I don’t want to have to switch out some LEDs if I mess up.

EasyB
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I’ve sliced the 219C. It does improve throw but not as much as traditional LEDs with bond wires. Like the XPG3, the throw might increase by 40 to 50% instead of 90%.

The_Driver
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I know, I still want to do it. The Meteor only has a good practical beam with dedomed LEDs of this size.

djozz
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I doubt MEM a bit in this. From my adventures with the 219C (mechanically and chemically) I concluded that the phosfor is not a compact thin layer but it is mixed inside a layer of silicone closest to the die, surrounded by a rim, and that layer is continuous with the clear part of the silicone dome next to it. Dissolve the dome chemically and you dissolve the phosfor layer with it.

I’m with X3, slicing is the way to go IMO

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