A140 melted bond wires

After having far too much fun with my 445 about 6 months ago i was greeted with a brief flash of white light and then nothing. I'll assume my driver went short circuit and let all the current from my 7.4v lithium-polymer battery into my diode...

Heres the host (before it died):



Today i decided to find out exactly what went wrong, the diode went open-circuit so i decided there was no chance of recovery, so i cracked it open (de-canned) to see what the damage was...

Me opening it like a man...


The results:


The bond wires to the centre of the diode seem a bit melted to me...

(Pics of the diode were taken with my IPhone 2g with the 445 colimating lense held infront of the camera, they came out quite well...)

I'll have a go at soldering it, i've seen someone do it before and i've got nothing to loose.

Be very careful and practice a few times before you have a go. I hope you fix it :beer:

EDIT: It looks like it was rough getting it open Ouch scissors...

And how high is it set at? You got it heat sinked? How long you running it for like that?

Should get a real driver IMO

LOL, it looks like you may have taken of a small bit of the block under the die too!. I saw in a different thread that someone had the same problem and managed to make a solder bridge to reconnect the melted wires. I think you sould have a go at it.

Krogith thanks for the tips but im not really expecting anything out of it so im not really botherd if i mess up. If it emits a single photon from this point that'd be a bonus for me.

And how high is it set at? You got it heat sinked? How long you running it for like that?

Click to expand...

It was running about 1.5A. The only heatsink was that bit of metal i was using to mount it with, but i did have that fan pointed at it and it seemed to keep below about 35C. I got about 5 hours of run time out of it in this setup, i had used it countless times before i decided to make it portable though, i think i overcharged the battery one day and that fried the driver... It died after a full charge one day about 6 months ago, to this day the battery is still holding 9.8v (it's rated for 7.4v...).

Should get a real driver IMO

Click to expand...

I agree, they were too expensive for me at the time so i just used a mosfet with current sense resistor, as the voltage increased accross the resistor the fet let less current through.

LOL, it looks like you may have taken of a small bit of the block under the die too!.

Click to expand...

Haha yeah i just squeesed until the top came off, it took a chunk out of the diode mounting block. Any ideas on what its made out of btw? seems really soft...

I saw in a different thread that someone had the same problem and managed to make a solder bridge to reconnect the melted wires. I think you sould have a go at it.

Click to expand...

Yeah I've seen that thread too. I'll just push a blob of molten solder in its general direction and hope for the best...

Amazing how the wires always seem to melt before the laser goes COD. Tough lasers. Who knows...maybe these guys can push 3W with thicker wires onto the die..

It didn't really go COD though, it just melted the bondwires.

@OP, try taking off the rest of the can as carefully as you can, it'll make resoldering those wires easier. The pedestal the die is mounted on is brass I believe.

It's a copper-tungsten alloy if I remember correctly.

-Trevor

Is that s CO2 laser in the background? Wicked!

Good luck on soldering the bond wires back together and as mentioned allready you will have to decan it completly to get to them.
I don't think you stand a chance but good luck anyway

put up some pictures if you get it to work, heck put up pictures even if you don't get it to work...

Is that s CO2 laser in the background? Wicked!

Click to expand...

Of course, no home is complete without a functioning 40w carbon dioxide laser

In response to the taking off the rest of the can;
I'll have a go, i'm not really sure what tools to use to get it off though...

I don't think you stand a chance but good luck anyway

Click to expand...

Ha, neither do I. Thanks anyway though

I'll go warm up the soldering iron, i'll put up pics when i'm done...

Oh dear,
Those guys over on the 445nm laser section are going to hate me for what i've done to one of their beloved diodes...

It's amazing how those wires can handle 1 amp or more in the first place, they are thinner than a human hair...
Well, i tried my best. (And made one hell of a mess)
I'll go try some point-contact stuff in a bit, i just want to see some light out of this thing one last time before i give up and throw it away.

holy crap, well in your defense im not so good on small delicate stuff.

nice attempt though but thats one sad looking diode.

did you melt the other side bond wires during this? Picture is kinda hard to see them.

The bond wires are only designed to take 500mA. The die looks somewhat alright, amazingly :na:, so if you can get that solder out of there and the other bond wires aren't gone, it may be salvageable.

Yep, all the bond wires are gone, unfortunatly

500ma? Thats still one hell of a lot of current for wires those size.
Suprisingly, the die does seem to be standing up to this treatment quite well. I expected it to crumble during my 'delicate' na de-canning process.

Think i'll give up on this, might have another go tomorrow possibly. It's killing my eyes working with somthing this small...
I'll look into getting some more of these diodes though, best and toughest i've ever used

I'd have taken the can off entirely.
Also you might be able to sacrifice an old Pentium CPU (the ones where the bond wires are easy to get to and solid gold) to make new bond wires.
Old transistors sometimes use them, especially antique power germaniums.

-A

"Bother!" said Pooh, as the BORG had no sense of humour.