Why do LPC diodes hate me?

[Jimmymcjimthejim]

Ok, this is really pissing me off. I recently had 4 (yes, that's right) LPC diodes fail on me. No clue why. I've been doing this for over a year now so I know how to build lasers, but this is supremely confusing me.
Two of the diodes, when first extracted from the sled, powered up with a strange projection. (see my other thread.)
One complete pointer, running at 330mA, was on for around 10 seconds pointing at a wall when it LED'd.
Recently, just minutes from posting this, I was pointing my altoids laser at a wall and gently puffing air from a squeeze bulb into the lens to clean it. It was at 130mA when it LED'd, after around 20 seconds of being on. For burning it was set at 260mA, so there's no pushing the diode there.
The two instantly broken diodes and altoids laser have the same projection from the diode.
So please tell me, what is going on?

 

[Eudaimonium]

You mean, LOC diodes? you wrote 'LPC'
No, the diode was not pushed with the current. But it may have been with spikes.
What kind of driver are you using? It is possible that the main regulator chip is defective or something, so it is giving unstable output.
Other than that, you maybe have the 1:100000000000 luck that you picked up every single diode defective.

 

[Jimmymcjimthejim]

I say LPC because all LPC diodes are LOC, but not all LOC diodes are LPC.
For all four I am using the groove driver. It definitely is possible that the driver is the problem, and in which case I would have to blame Kenom because I got the parts/design from him.
On a more serious note, it seems that my family has lots of bad luck, maybe it's hereditary :thinking:

 

[ColdStl]

I've had similar results with the LPC, killed too many of them and couldn't figure out why. I wasn't pushing them hard at all, and all where heatsinked adequately...good solder connections too.
I mainly use LCC now and haven't had any LED as of yet. They may not be as powerful, but seem to be more durable.

 

[billg519]

Long open can, by definition, places the die at some risk of contamination. The closed can diodes protect the die from dust, humidity and other dangers. The open can is especially at risk in an aixiz housing if the spring is used. The lens nut turns against the end of the spring, occasionally milling off tiny little bits of metal and plastic. If one microscopic bit lands on the output facet, it is truly LED time. If the laser gets cold outside and is brought into a warm environment, condensation on the die may kill it the next time the laser is powered up, or soon after. C-mounts and open can 9mm diodes face the same risks.

 

[RA_pierce]

What Billg519 said.
Open cans are sensitive in this way. Blowing air onto the lens may have caused particles of metal or dust to contaminate the die. Having an adjustable focus and spring in the lens assembly can be dangerous for diode types with an exposed die.
I like to use LCC diodes for this reason. In my experience, the LCCs are equivalent to the LOC in power output.

 

[Jimmymcjimthejim]

Thanks for the explanation billg. Yeah, I'm starting to go a bit crazy here..
Question: Do LCC diodes have windows?

 

[RA_pierce]

Thanks for the explanation billg. Yeah, I'm starting to go a bit crazy here..
Question: Do LCC diodes have windows?

Yes. Mine do at least.

 

[billg519]

I've had these deaths happen to me and it took me a while to figure out what was going on. I had to inspect a dead LOC with my Fuji medical microscope and see a piece of crap on the output facet. Then I clued in as to why I would lose a diode for "no good reason". When I kill another, I will shoot and post some microscope pics ...

 

[Eudaimonium]

I agree with condensation of moist theory. Other ther than instable output.
Guess that it would help to remove the spring in module to prevent getting bits of metal to the chip die. However you wouldn't be able to get stable focus.
I have never used LOC before, i always used LCC, not one diode died without my 'expert touch'.
Long ago, before i found about test load, that is.