Show your busted XM-Ls!

We all have our oops moments.



I just happen to have 2. Let's just say, those bond wires weren't meant to carry whatever current jumped into them at ~19V.... :scowl:



while de-doming, the bondwires broke, but if you look closely (not too closely), you'll see that the middle of the left one, and left bond wire of the right one are uh, toasted.







I scraped the phosphor off the left one.





over there in the corner is the ESD protection diode. uh, it got scraped off on the left one







let's have a look at the LED, with different lighting:

Interesting, and nice pics!

Any chance to remove the dome without ripping off the bonding wires? I fear they are submerged right in the silicone..?
I would love to convert one of those old XR-E to a blue LED.. must be amazingly bright!
Another concern would be if the die itself survives contact to the air. Maybe recoat it with Norland or the like?

Manuel

norland noa#61 starts turning brown if you use it as an LED encapsulant on an XR-E. <from experience.

I love macro pics of LEDs, and while these are just scaled up looking, it's interesting to note the details of the LED. Also, strange rounded corners on those new dice, or are those just remnants of the dedoming process?

Nice pics, C.

krutzbeuazen said:

Interesting, and nice pics!

Any chance to remove the dome without ripping off the bonding wires? I fear they are submerged right in the silicone..?
I would love to convert one of those old XR-E to a blue LED.. must be amazingly bright!
Another concern would be if the die itself survives contact to the air. Maybe recoat it with Norland or the like?

Manuel

Click to expand...

As http://www.candlepowerforums.com/vb/member.php?64137-bshanahan14rulz bshanahan14rulz said Norland is a no-no. Dedoming the XM-Ls is possible without breaking the bond wires but you do run a significant risk of breaking them. May take you a few tries. The XR-E however is much easier to dedome as the silicone under the glass is much softer and can be scraped away fairly easily. If you want blue though it would be far easier to just buy the royal blue LEDs which white is based on to begin with.
http://www.candlepowerforums.com/vb/member.php?64137-bshanahan14rulz

awesome, thank you for those real-world hints, bshanahan and saabluster!
Sure, royal-blue LEDs are easier.. this is not a "real" project, just experimenting. I have XR-E LEDs here and no blue ones, so I will have a try or two. Any suggestion on what to use to seal the die? plain clear epoxy, better than nothing? or, well, nothing then?

Will report back eventually, with more busted macro pics

Manuel

krutzbeuazen said:

awesome, thank you for those real-world hints, bshanahan and saabluster!
Sure, royal-blue LEDs are easier.. this is not a "real" project, just experimenting. I have XR-E LEDs here and no blue ones, so I will have a try or two. Any suggestion on what to use to seal the die? plain clear epoxy, better than nothing? or, well, nothing then?

Will report back eventually, with more busted macro pics

Manuel

Click to expand...

No epoxy is going to work in this application. You would be far better off even with the cheap hardware-store clear silicone. Still not the best but better than epoxy. Best would be to use the kind of silicone the manufacturers use.

Also when scraping it is best to use something soft like a wood tooth-pick so you don't damage the die.

I need one piece of waterproof sandpaper grid 400 to sand a XM-L to 0.2mm.
Plenty of water and a gentle and clean finger on top of the dome, regular cleaning and checking the Led.
To be on the safe side I dremeled-off the wires going through the base.
Removing the Led, being glued with Arctic Silver 5 epoxiy, it broke.
Lack of experience probably, but I was once again disappointed by the thickness of the glue while having it clamped by several Kilo's on the Led.

Have my hope on the copper star, prefer clamping-force by bolts-and-nuts and thermal paste, drilled all through the heatsink.
Path from die to heatsink is really important for high currents, as we know.

bshanahan14rulz said:

I love macro pics of LEDs, and while these are just scaled up looking, it's interesting to note the details of the LED.

Click to expand...

ouch. as a hobbyist photographer that statement kind of hurt.
time for a reshoot!





then at 100%: http://www.incoherentphotography.com/uploads/SS-2011-03-16_17.17.29.jpg

these leds have been knocked around on my desk for a while. didn't really bother taking care of them.

csshih,

I didn't mean to offend, I just meant that I'm amazed by macro shots, even though a macro shot is just a very close-up picture. Those are great pics, and I mean it! I can see the field of focus centered on the die, the textured "extraction layer," beautiful pictures. At least my vague comment opened the way for a reshoot

Nice macros! Are the domes made with more silicone layers?