C-Mount 808nm broken lead - How to fix?

[celas]

What is the best way to attach a broken negative lead in C-mount diodes?
Careful soldering or some kind of conductive glue? I accidentally broke of negative lead from high power 808nm IR pump and I need to get it working again. What are your methods of dealing with this kind of situation?

 

[diachi]

Do you have a picture of the damage?

 

[celas]

Yes I do. The negative lead is completely gone. Since soldering isn't an option because I'll fry the diode before solder will stick to this almost unsolderable surface, I was wondering if Ag based glue for trace repair would work - I could buy this easily.

This is not the first time this happened, these negative leads are notoriously fragile but this time we are talking about a damn 5W diode - no way I could afford another one right now

 

[diachi]

Yes I do. The negative lead is completely gone. Since soldering isn't an option because I'll fry the diode before solder will stick to this almost unsolderable surface, I was wondering if Ag based glue for trace repair would work - I could buy this easily.

This is not the first time this happened, these negative leads are notoriously fragile but this time we are talking about a damn 5W diode - no way I could afford another one right now

Ag glue or anything like that will likely have a far higher resistance than a proper soldered connection, that'll cause issues and I don't believe it will work. Might have been an option with much lower power diode.

If your soldering skills are good (i.e. you're proficient at SMD size soldering) you might be able to solder a thin strip of copper shim stock to what's left of the contact.

If you go the soldering route, make sure you have plenty of airflow over the diode blowing any vapor/smoke away from it so that contaminants don't get deposited on emitter facet.

Someone else may chime in with a better solution but that's how I'd go about it.

 

[Alaskan]

I've used a silver based circuit board trace repair pen and it works for a couple of amps or more on the boards, you might look into finding that, if it is still sold, been 25 years since I've worked with it.

 

[Hemlock_Mike]

Alaskan is right because I think a similar product
is used to repair rear window heater traces.
It may be copper or silver. Try some on an insulator
and check current capability - it might take a couple coats.
HM

 

[celas]

I've used a silver based circuit board trace repair pen and it works for a couple of amps or more on the boards, you might look into finding that, if it is still sold, been 25 years since I've worked with it.

So it doesn't only happen to me? :san:
Well, I've decided to leave this diode in a sealed bag and wait until I buy nice soldering station and learn to use it - then I might practice on some dead diodes and finally fix it. Maybe Alaskan is right but I too have doubts about 4.5A flowing through a glued connection (its a 5W diode)

 

[Alaskan]

If you find someone who makes those silver circuit board repair kits, they might provide some kind of specification of current capability. For those, it isn't a glue, it's just a conductive trace made with silver, once dried.

 

[WizardG]

Two words: indium solder

 

[Hemlock_Mike]

WizardZ --- Great idea. There is also low temp bismuth solder.
Flux will always be a problem here. I have a SMALL amount of
bismuth solder if you need a few inches!
HM

 

[Singlemode Laser]

I used sort of a clamp to press a conductor to the diodes area. Worked very well without soldering (you have just to make a rigid clamp). Since than I always clamp the lead of a C-mount.

Singlemode

 

[diachi]

I used sort of a clamp to press a conductor to the diodes area. Worked very well without soldering (you have just to make a rigid clamp). Since than I always clamp the lead of a C-mount.

Singlemode

You can buy mounts specifically for that, though I'm not sure how cheap you'd be able to find them.

Obviously no good for a build, but it'd do for testing and something similar in principal would work fine on a smaller scale.

 

[WizardG]

WizardZ --- Great idea. There is also low temp bismuth solder.
Flux will always be a problem here. I have a SMALL amount of
bismuth solder if you need a few inches!
HM

Indium solder on a gold pad? Work with a very low temp iron and no flux will be needed. The indium/bismuth alloy solders have much lower melting points (some as low as 70C) than ordinary solder that make oxidation a non-issue.

 

[celas]

By the way guys - I am in need of C-Mount 808nm diodes from 2Watts UP that I'd gladly buy from you if you have some left (slightly used would be best cause probably cheaper than new ) , or even better trade - I have tons of miscelanous laser stuff you'd maybe be willing to trade for some 808 Cmount diodes - i have 2 CNI 473-III heads with drivers and PSU's without diodes (taken from RGB projectors, diodes are dead [degradation after looooong years of duty, still output like 30% of their power but its nowhere near enough] but rest is fine), IFLEX Head (cool looking lab sciencey laser, might be useful for some project) but I took diode assembly, TEC, and prisms - the crazy Mhz range analogue modulation driver is still there, two 405nm high quality kineflex singlemode fibers, 650-I Cni 500mW modules and lots of more. Anyone up for a trade?

 

[rustynuts]

were you able to get the diode fixed yet? if not I think I can fix it, for years I have been a soldering specialist for local shops in my area for some time now.

 

[celas]

I fixed it. After many failed attempts I decided to do a nuclear-soldering-option (I was pissed off and I didnt care if I break it or not anymore). Surprisingly, it worked, and diode works well and still holds rated power (althought operating voltage rose a bit, maybe because my solder joints wont be as good as the factory ones). For anyone trying to fix a broken c-mount lead: just use your soldering iron on maximum temperature (in my case 500 deg C), otherwise solder wont stick to the brass/copper-tungsten surface. As long as you dont exceed 3-4 seconds contact, diode wont be damaged