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On a sunny day (Sun, 19 Jan 2014 11:28:10 +1100) it happened Chris Jones wrote in :

Freon?

Used that to clean video record heads, before the green mob protested.

Hey, John -

If you still have that little leak-test pcb lying around, maybe you could test it again to see if exposure to the moisture and contaminates in the air have had an effect on the flux. If it's not too much trouble.

John S

I don't know if it's still around. I did let it run for a couple of weeks, and the humidity was fairly high. Just breathing on it had no effect, meter still pinned.

Thanks for showing that.

Perhaps my mistake was trying to clean it, or perhaps I had lower-resistivity crud on my board. Either way a new (DIP) chip was a substantial improvement over my best cleaning efforts. Next time I will try a few more experiments.

Chris

Hi John S. A few years ago I mucked around trying to get rosin flux to le ak. I breathed on it, exposed it to water, burned the 'piss' out of it wit h an big solder gun... some of the ugliest solder joints you can imagine. I couldn't get it to leak at all. (pA level, 10V bias.) one cavet is that this is all low voltage (~10V) testing. One might worry that at higher vol tages there be some other mechanism. (how high? geesh I have no idea)

George H.

Great! Thanks for that. My interest is in the lower voltage range, so not a problem.

Cheers, John S

Water soluble flux is awful for leakage, and needs heroic washing in DI water to get the leakage down. I tested one "no clean" flux, and it was OK, but I hate no-clean flux because it's so hard to clean.

Should be "can't clean"?

I thought that "no clean" for PbSn pastes was another name for normal RMA rosin.

Cheers

Phil Hobbs

NO! It's something else. Something bad.

Best regards, Spehro Pefhany

P.S. If that was a joke, sorry for not getting it.

Best regards, Spehro Pefhany

What I said!

What John said.

The sad this is that this stuff is okay for most digital-heavy stuff (and a lot of the sensitive analog stuff takes place safely under a layer of passivation inside a chip), so they're not under a lot of pressure to change their processes for a few analog types.

--sp

itors that I was using.

It wasn't so much the green mob protesting as the appearance of the Antarct ic ozone hole.

Cutting back on chlorofluorocarbon solvent use does seem to have started sh rinking the ozone hole, so your sacrifice was not in vain. Turning Fred Sin ger into a burnt offering probably wouldn't be an equally effective sacrifi ce, but many still find it an attractive idea.