Emitter Dome Artifacts? curious XM-L development

LED Flashlights – General Info
1

When staring recently into the head of one of my lights, I find this:

A tiny artifact (until a better description is forthcoming) that is magnified many times by the reflector . . .

Is that also a crack at the bottom?

This is the 3-mode UltraFire XM-L from Manafont and it happens to be one of the best drop-ins I have. This particular example also has the best tint and beam profile of the dozen or so of these I have. In short, it is the best one to date I have received . . . even with a spot on it.

My question of course is; how/why did this happen? Is the crack responsible? Am I responsible? Is crack responsible? Is Foy on crack?

crackingupFoy

2

When I think about how these things are driven on high... I must immediately think about thermal issues that must come along with these high currents in a P60 dropin. Also the green PCB outside the dome looks like it has been exposed to an immense amount of heat. Did you use it for longer times on high?

3

I´d say about 50% or more of my low-budget XM-L´s have some flaws in emitter dome.

These include the UF 504´s discounted from DD (4 ordered) as well as those Skyray STL-V2 (still yet to receive a flawless domed one, 3 ordered).

IMO about 80% of dealextremes "1000lumen bicyclelights" has at least some flaw in dome. I recall receiving 1 or 2 flawless-domed so I say only 80%.

4

Foy, the emitter had that issue after some use, or you received it already damaged?

Yup, that’s true I think, I had a Magicshine XM-L T6 that has got something like a diffuser on the dome, may be because of excessive heat when soldering, I’ll never know.

I add that all the XM-L i have received from Cutter are flawless (the only non-Chinese supplier I have experience, so may be there are some other good ones).

5

Yes, Magicshine was the "brand". Maybe bad settings at re-flow line.

My separately bought emitters have also been flawless.

6

That is really strange that looks like one of the boards KD uses on it's XMLs. I haven't seen a Manafont drop in with that particular XML emitter board before. I also have never seen anything like what is going on inside the emitter dome very strange. It looks like the adhesive on the dome failed cracked and allowed some contaminants to get in there and the heat cooked it to the inside of the dome.

7

My speculation on that artifact on the surface of the dome, any chance it came from the soldering iron while they were soldering the emitter?

8

There is almost no doubt in my mind that what you are seeing is solder flux on the dome. It's very corrosive and turns that exact color when heated. It probably got on there when the wires were soldered to the star board - it's very evident that very high heat was used to solder those connections and RMA flux-core solder was used. RMA tends to bubble and pop when it's heated higher than necessary, and one of the splatters attached to the dome. A light bristle tooth-brush and some alcohol will reduce the dis-colorization, but damage has almost certainly been done to the dome.

PPtk

9

The shape of the burn mark would suggest that this may be the case.

From a practical standpoint, I would be more concerned by the crack.

The dome material is hygroscopic. I wonder if periods of exposure to the humidity in the air, followed by heating during operation had something to do with the separation?

10

I'm fairly certain it's the 3-mode UF from Manafont - it just pulled 3.83 amps in an L2P with a well worn SF 2400.

turbo - One of the pics had me thinking it was on the outside, too. With an LED magnifying glass, I attempted a careful rub/potential scrape. I wasn't too aggressive . . . . didn't want an unintended de-dome event. Although, I have considered a de-dome experiment, this is (was) one of my prized drop-ins.

Nearly every sku 5720 XM-L I have is outstanding but no two are alike. And, over the last 12 months the tints have improved and so has quality. I think Vectrex may be right; I've fed this poor fellow 3.70+ amps for extended periods and I'm thinking the crack may have something to do with it.

It still works great and remains intesely bright.

Foy

11

Okay, I'm with Pilot and Chicago; it must have been there all along and perhaps got darker with use, until it was dark enough to catch my eye.

repostFoy

12

This made me laugh .

13

Can't remember what I was doing . . . . sitting somewhere . . . . the bathroom maybe?

yeahthatwasitFoy

14

Sitting in the bathroom with an XM-L. Okay…

First thought was flux, glad PPtk said it first, as he said it much better than "hell that's Flux!"

Ever since I started buying emitters through Mouser, I have been getting excellent results. Not only are the emitters perfect, but the packaging is awesome. From what I see of the soldering jobs on many overseas drivers, I figure someone is actually doing a worse job over there, than I am doing here!

Foy, maybe it's just dirt on your camera lens.Tongue Out

15

Emitters from Digikey, Mouser, Avnet, Arrow, etc (Any of the franchised distributors) are going to be perfect. If you have that option, I would strongly suggest getting raw emitters from them rather than WallyWongsLedHut.com.

Soldering XM-L's (or any Cree style emitter) is a pain, but its far from impossible to achieve (near) perfect results.
These three emitters were soldered by hand, using two irons. Even the center heat-pad is soldered.

One of the secrets is to use water-soluble flux rather than no-clean or RMA. Yeah, you have to wash it after, but the job looks better and it's much more friendly to work with. You can never use to much water soluble flux - drown the things. Your soldering results will be so much better.

PPtk