A Perfect Dedome?

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MRsDNF
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Thanks djozz.

Your 50 x SST-40 order makes my order of 4 feel slightly insignificant. Smile
Good luck.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

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Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

18sixfifty
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The toluene took the dome off very clean. I did slice the dome off pretty close to the bottom before soaking. I didn’t boil the emitter on a hotplate. I used the boiling water instead like I would with gasoline. It’s VERY clean. Perfect. Now I’ll build a light with it in a while and report back on the tint. And I’ll compare that tint with the tint from the Hot high octane de-dome.

So far so good, keep your fingers crossed for me.

I’m a junky, I mod lights so I can sell lights so I can buy more light to mod so I can sell lights to buy more lights to mod.

18sixfifty
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MRsDNF wrote:
Thanks djozz.

Your 50 x SST-40 order makes my order of 4 feel slightly insignificant. Smile
Good luck.

Thanks Steve. Well the toluene worked perfect and the tint change was minimal. I didn’t see any green in it at all.

I’m a junky, I mod lights so I can sell lights so I can buy more light to mod so I can sell lights to buy more lights to mod.

khas
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Sledgestone wrote:
How much did you heat the mcpcb? Just enough to melt the solder under the LED or longer than that? And did you use a hot plate or iron?

I use this re-flow block I made for my soldering iron :

I really haven’t had time to redo the experiment but maybe one/two minutes in total ?, it was more or less trial and error if it was still green I gave it some more heat Big Smile

18sixfifty wrote:
The toluene took the dome off very clean. I did slice the dome off pretty close to the bottom before soaking. I didn’t boil the emitter on a hotplate. I used the boiling water instead like I would with gasoline. It’s VERY clean. Perfect. Now I’ll build a light with it in a while and report back on the tint. And I’ll compare that tint with the tint from the Hot high octane de-dome.

So far so good, keep your fingers crossed for me.

Great news thanks, twelve de-domed SST-40’s ? that’s going to be some kind of monster.

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18sixfifty wrote:
MRsDNF wrote:
Thanks djozz.

Your 50 x SST-40 order makes my order of 4 feel slightly insignificant. Smile
Good luck.

Thanks Steve. Well the toluene worked perfect and the tint change was minimal. I didn’t see any green in it at all.

Good work! Luckily we have straight toulene to buy here in Sweden, so I’ll probably order some today. The thinner I use now is 80% toulene and 15-20% acetone and the dedomes I’ve done with it turned out too green. I’m suspecting that the acetone is the culprit as I’ve read that it might eat some of the phosphorus when used.

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Been on a local supermarket a while ago. They now sell a “turpentine simile” whose composition is: C7 and C9-C12 alkanes in n-alkane, isoalkane and cycloalkane forms. Looks good to me, gonna get a bottle tomorrow. Half a litre for €1.60. 

 

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Well, i hate to say it but Cree has changed the dome`s sillicone again…..hard times for dedoming are comming folks…XPG2 and XPL are already affected but the change

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Mitko wrote:
Well, i hate to say it but Cree has changed the dome`s sillicone again…..hard times for dedoming are comming folks…XPG2 and XPL are already affected but the change

What are the symptoms of the new silicone on the XPL and XPG2?

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Why does a perfect dedome work well?
If I understand DrJones correctly, even a flat dome should reflect less light back towards the phosphor than no dome at all. Reflection of perpendicular beam is down from 18% to 10% (6%+4%). TIR angle is the same. So total reflection with a shaved dome should be lower, producing better output and smaller tint shift. But numbers here, here, here indicate otherwise.
Can someone explain why is it so?

18sixfifty
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Agro wrote:
Why does a perfect dedome work well? If I understand DrJones correctly, even a flat dome should reflect less light back towards the phosphor than no dome at all. Reflection of perpendicular beam is down from 18% to 10% (6%+4%). TIR angle is the same. So total reflection with a shaved dome should be lower, producing better output and smaller tint shift. But numbers here, here, here indicate otherwise. Can someone explain why is it so?

I have never seen a “perfect” shaved dome. So there is more lumen loss with a shaved dome because the top is no longer as smooth and perfect as with the dome on. I imagine there is still some scattering of the light because of the imperfections in the “top” of the emitter. Not that I think a “close shave” de-dome is bad, because done properly it is still a good way to de-dome.

I’m a junky, I mod lights so I can sell lights so I can buy more light to mod so I can sell lights to buy more lights to mod.

Agro
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18sixfifty wrote:
Agro wrote:
Why does a perfect dedome work well? If I understand DrJones correctly, even a flat dome should reflect less light back towards the phosphor than no dome at all. Reflection of perpendicular beam is down from 18% to 10% (6%+4%). TIR angle is the same. So total reflection with a shaved dome should be lower, producing better output and smaller tint shift. But numbers here, here, here indicate otherwise. Can someone explain why is it so?

I have never seen a “perfect” shaved dome. So there is more lumen loss with a shaved dome because the top is no longer as smooth and perfect as with the dome on. I imagine there is still some scattering of the light because of the imperfections in the “top” of the emitter. Not that I think a “close shave” de-dome is bad, because done properly it is still a good way to de-dome.


That was my first thought too. But @relic38 has sanded the shave with 2000 grit paper. I think it should be OK…
Another thought is that in a perfect dedome there’s still a thin layer of silicone left.
Or maybe there’s some more fundamental reason.
Dunno…
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Just killed a LatticeBright “XM-L” by driving it directly from a 3.5+V battery while submerged in white spirit. Gave it a few good zaps a few hours ago, can't say for sure if there was some apparent damage mostly due to my unwillingness to look at the thing while driving it.

Gave it another zap a few minutes ago, and it just died. 

I have an old genuine XM-L next in line, but now I am in doubt with regards to submerging it with wires attached. 

 

Please avoid fully quoting lenghty posts, namely with nested quotes. Trim quotes down to the essential. Helps with neatness and legibility. Thanks.

The human mind, and its programming, is at the forefront of a particular battle of The Light vs evil dark forces. Nearly every human being on this beautiful planet “Earth” has some sort of negative mind programming in its mind. And you better take care of your mind programming, or someone else will in this wicked world.

Barkuti
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2013 manufactured cool white XM-L is enjoying a white spirit bath, with attached wires. I've given it some current, but the alu board doesn't even seems to get hot to my finger. Maybe the mia LatticeBright “XM-L” was already “cooked”, it came from a friend's headlamp whose emitter I swapped.

Going to raise the battery voltage to increase my diver's driving current. Big Smile

 

Please avoid fully quoting lenghty posts, namely with nested quotes. Trim quotes down to the essential. Helps with neatness and legibility. Thanks.

The human mind, and its programming, is at the forefront of a particular battle of The Light vs evil dark forces. Nearly every human being on this beautiful planet “Earth” has some sort of negative mind programming in its mind. And you better take care of your mind programming, or someone else will in this wicked world.

FmC
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I gave the submersed current method a go a while back, trying to cleanly de-dome some Oslons.

It had promise, but I ran out of emitters…. Smile
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0K, at this point I believe the LatticeBright XK/XL I was bathing maybe died from overcurrent.

Estimating:

  • Test battery: two worn out King Kong INR26650E cells in parallel; let's say ≈40mΩ of internal resistance.
  • Multimeter and its leads, ≈200±50mΩ of resistance.
  • Emitter wires: ≈½ a meter both positive and negative, AWG24; 86.56mΩ.

This at least ≈277mΩ (≈277mV/A) from the measuring setup. Checking the current flow to the submerged XM-L revealed from 1.5A to nearly 2A, with a no-load battery voltage of only 3.54V! Bold sheesh fellows!

Test XM-L may be getting ≈3A when the multimeter is removed. Remember my testing is being done with my led's bathing fluid at room temperature, this means Vf remains higher also (excellent cooling).

I can see many of you may have killed a good deal of emitters this way because of hot bath (less Vf) plus high starting battery voltage. Seriously. 

 

Please avoid fully quoting lenghty posts, namely with nested quotes. Trim quotes down to the essential. Helps with neatness and legibility. Thanks.

The human mind, and its programming, is at the forefront of a particular battle of The Light vs evil dark forces. Nearly every human being on this beautiful planet “Earth” has some sort of negative mind programming in its mind. And you better take care of your mind programming, or someone else will in this wicked world.

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A little update with this stuff. ( ಠ ͜ʖರೃ)

My old XM-L was left in the white spirit bath, waiting for nature to take its course. I extracted the board a few days ago and the dome nearly fell by itself, leaving just an unimportant tiny leftover where the bond wires are, yet not over the die which is… completely clear! (ᵔᴥᵔ)

I know have an XM-L2 in the bath. The good thing with white spirit is that it does not seem to completely evaporate at room temperature, of course because of the longer chain hydrocarbons.

It is fun to observe the white spirit slowly doing its magic and giving it some stirring just for the sake of it. I can clearly see a curious optical effect in the emitters while immersed: the die looks unscaled, like if it were dedomed. As time slowly goes by it can be observed how the white spirit diffuses under the dome, progressively soaking the die under. 

If anyone is interested I believe this slow cooking method may be worth a try with the newer generation Cree emitters.

 

Cheers my dears 

Please avoid fully quoting lenghty posts, namely with nested quotes. Trim quotes down to the essential. Helps with neatness and legibility. Thanks.

The human mind, and its programming, is at the forefront of a particular battle of The Light vs evil dark forces. Nearly every human being on this beautiful planet “Earth” has some sort of negative mind programming in its mind. And you better take care of your mind programming, or someone else will in this wicked world.

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18sixfifty wrote:
MRsDNF wrote:
Thanks djozz. Your 50 x SST-40 order makes my order of 4 feel slightly insignificant. Smile Good luck.
Thanks Steve. Well the toluene worked perfect and the tint change was minimal. I didn't see any green in it at all.

18sixfifty - so is toluene the best way to go? Have you done more SST-40's, and same good results?

giorgoskok
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I used nitro paint thinner to dedome SST-40’s .

Warm or not , they dedome pretty fast … Just be carefull not to leave them after the silicone dome pops off.

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Yea, I read thru dozens of posts, and could not find anyone that found and used nitro in the US. Not sure if Toluene is any easier to find though.

This stuff: https://www.scalehobbyist.com/catagories/Paint_and_Construction/nitro-thinner-use-w-clear-colors/AKI00000268/product.php

It's 3.4 ounces (100 ml) and would be $16 shipped frown

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Yeah, it’s apparently the toluene that does the job best.
I.i.r.c. the nitro thinner contains toluene, unlike regular cellulose thinner.
But toluene is hard to come by (and i think it’s rather toxic too).
That’s why nitro thinner is presently the go to solvent, but it’s not easily available in every country.
I can order a liter online, but it’s some $15 including shipping cost.

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giorgoskok wrote:
I used nitro paint thinner to dedome SST-40’s .

Warm or not , they dedome pretty fast … Just be carefull not to leave them after the silicone dome pops off.


Why not? What happens if you leave it in there for a longer time?
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A more common name for toluene is toluol.

Its available at Home Hardware in Canada and at Menards in the States. Probably find it at a lot more places if you check.

https://www.menards.com/main/paint/cleaners-thinners-removers/paint-stai...

Home Hardware also sells a lacquer thinner made up of toluene, methyl alcohol and methyl ethyl ketone, that seems like a pretty nasty combination.

Mem talked about his method of dedoming being a two step process, attack the glue first then swell the dome off. I can’t figure out if he was using different chemicals or wetting the base of the led for a while and then submerging it.

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Thanks, toluol.
Also (under that name) not easy to obtain..

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I think it’s banned as a paint thinner in your country. Another name for it is methyl benzene.

Do you recognize any names from this list? http://www.chemspider.com/Chemical-Structure.1108.html

Are there any places around that replace fiberglass boats or kevlar kayaks that you can check with?

Has anyone tried lighter fluid or kerosene yet?

Failing that you can try hot dedoming, this guy makes it look easy. https://www.youtube.com/watch?v=NN2gVjw7eV0

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Well, that wasn’t too difficult afterall.
For the Dutchies:
https://www.fixxar.nl/elma-elma-thinner-tolueen-1-l.html
Probably not 100% toluene, but i think it’ll do.

(edit) O, dang… Their supplier had it wrong, they sent me normal thinner…
dispute in progress… Tired

Update: http://budgetlightforum.com/comment/1187951#comment-1187951

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Well , i found here Nitro paint thinner easily , in comparison with ither chemicals that i can’t even order online .

Price was good i think , 3.3€ for 1L .

Jerommel wrote:
Why not? What happens if you leave it in there for a longer time?

I think it weakened the bond wires so the led popped …

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@Tom I also couldn’t find Nitro thinner. I read somewhere that MEK worked, so I started using it. The SST-40 dedomes nicely with it. The couple of XML2 U4-1A’s I did in it had the usual tint shift.

Readily available at HD. I have only tried it hot, so not sure how well it works cold.

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Thanks Scott. Yea, my original plan was to get some MEK, but seems like everyone is only talking about toluene now. I'll get the MEK for now then.

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All,

The answer may have been under my nose this whole time (some pun intended there). I’ve been using a solvent called Wil-Bond made by imperial. I don’t recall ever trying to do a full chemical dedome with it for fear of phosphor damage and generally I’m impatient. BUT – I have used it with much success to clean up the bits left behind during my hot dedomes and it seems to make quick work of the silicone scraps. So I looked up the MSDS and compared it to the solvent list I’d linked previously.. What I found is that it’s full of theoretically effective solvents. I will say it’s odor is definitely nothing to be taken lightly. Even the can sealed up and in a cupboard, I can smell it on hot days when I walk into my hobby room. The good news is it can be found in the US at Walmart and has free shipping for ~$18

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I’ll throw a few sacrificial LEDs in there tonight sometime and see what happens. I don’t think I’ll try heating it at all. Don’t have the appropriate space or heating equipment for that right now.

LEDs that I might have to try..

XP-L
219B
XP-E2
XHP-70
MT-G2 (MAYBE)

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