Just be aware if this stuff does eat Epoxy, the PCB itself is probably toast. Guess what most PCB's are made of?

 

It is amazing how often crossed fingers are a vital part of success in the lab yet not required once a product goes into production.

You mean there are actually cases out there of people that succeed at something without crossing their fingers???
Thanks Gopher, you made me laugh today ...

 

I have high hopes and am Daumen drücken.

John

 

I have high hopes and am Daumen drücken.

John

Here's what Daumen drücken looks like...

 

OOOOOkkkkk....
After being submerged more than 24 hours, the NMP has done absolutely nothing, zero, zilch, nada to the component... I'm beginning to think that it's no organic thing what we're dealing with, but some strange kind of composite ceramic or something...
It seems I've run out of options here... other than grinding the freaking thing with my own teeth...

I'm going to meditate some more on this issue and then I'll get back to you with my (most likely empty) insights...

 

Drats. The other options are pretty wild, as we have discussed (like nitric acid, molten NaOH/NaNO3, etc.) That leaves physically grinding like archaeologists do or X-ray/CAT scan. I would use a round or tapered cylindrical carbide burr in a Dremel. After you get most of the epoxy off, then heating at 150°C should make it soft enough to pry off in small pieces.

I am disappointed. John

 

I am disappointed. John

Me too... maybe I didn't cross my fingers right... or pressed my thumbs correctly... or the other way around...
Anyway, I'm getting quotes for x-raying the thing... see if I can afford it

 

The commercial rate may be quite high. If you are near a university or other teaching hospital, you may find a resident in radiology or pathology who will help you as a challenge. That is, for a simple X-ray. John

 

On the other hand, I'm going to get a small piece of common grade epoxy and dump it in the jar too, see what happens to it... this to make sure that my supplier gave me the proper sample...

 

Also, take an old painted surface, the more old coats the better. Add a drop and let sit for several hours. It should remove the paint. NMP has a distinctive, but mild odor. It is not at all sharp and penetrating like methylene chloride.

John

 

Also, take an old painted surface, the more old coats the better. Add a drop and let sit for several hours. It should remove the paint. NMP has a distinctive, but mild odor. It is not at all sharp and penetrating like methylene chloride.

John

Yeah, the lack of a sharp odor is the first thing I noticed about the sample... it's a little nutty, if I could describe it in a word... Gonna follow your advice, thanks

 

That is a pretty good description of the smell.

John

 

That is a pretty good description of the smell.
John

I forgot to mention that another characteristic is that it is a very thin fluid, with very low viscosity

 

I found this very interesting video, but unfortunately it doesn't apply to what I want to do, since the part is too complex and has metallic parts embedded in it:

 

Acid digestion, sometimes called chemical ashing, is one of the more vigorous methods mentioned. Also, molten NaOH + NaNO3 will probably work. Unless your item is very small, I don't think you want to use either method. Moreover, even with those methods, you need to grind away as much epoxy as practical.

You have raised a question whether the potting is really epoxy. Have you tried burning a chip or sliver of the material?

Any luck finding someone to X-ray it?

John

 

Acid digestion, sometimes called chemical ashing, is one of the more vigorous methods mentioned. Also, molten NaOH + NaNO3 will probably work. Unless your item is very small, I don't think you want to use either method. Moreover, even with those methods, you need to grind away as much epoxy as practical.

You have raised a question whether the potting is really epoxy. Have you tried burning a chip or sliver of the material?

Any luck finding someone to X-ray it?

John

Thanks for the follow up, John. Yes, there are several suppliers of services relating to metallurgical analysis in the area, and among the range of services that they offer is x-rays (even gamma rays and other more advanced stuff). I'm having the part tested this week, and see how it goes. I've asked them to take x-ray video of it and not just stills so as to get a feeling on how it's constructed. On the other hand, I'm sending another part to a workshop where they're going to mill it in half, so I can see a cross section of it.
I haven't burned a sliver of the part... but now that you mention it, I'm going to do that now... I'll get back to you later with my observations. Thanks again.

 

Ok... just got back from the kitchen, where I placed a small chip of the material above the stove, and sure enough, it got really hot until it caught fire, but it didn't change its shape. It smoked a little bit, but I couldn't detect an odor (strange, isn't it?) Anyway, after about 1 minute the chip stopped smoking and flaming, but I kept it on the fire for one minute more. I let it cool for a couple of minutes after that, and after careful inspection I could tell that the material didn't change shape noticeably. So I pressed it a little bit using pliers, and the thing turned to dust! An "uncooked" chip is much harder to crack, and it turns into smaller chips, not into dust as this one did..... I love mysteries, but not when they're work related.... *the plot thickens*

 

Save that dust.

See if a portion is soluble in water. Check another portion in HCl or battery acid. Check a third portion is NaOH (lye). Save any remainder. There are ceramic and alumina-based potting compounds. If it is one of those, we have been going up the wrong road -- not that we can remove them any more easily.

John

 

Save that dust.
See if a portion is soluble in water. Check another portion in HCl or battery acid. Check a third portion is NaOH (lye). Save any remainder. There are ceramic and alumina-based potting compounds. If it is one of those, we have been going up the wrong road -- not that we can remove them any more easily.
John

Is HCl the same as muriatic acid?
Another question... how high a temperature do you think my natural gas stove was able to pull on the sample? Would you say it's below 600 °C ? Because if it is, then maybe I can put the thing in an industrial oven and turn all of that stuff into dust, whilst any steel and cooper would remain undamaged, though I know that all insulation material will be affected too, but no matter.

 

Yes, another name for HCl is muriatic acid. For this purpose, it would be my first choice over battery acid (sulfuric acid). Flame temperatures vary depending on the oxidant (oxygen vs. air) and fuel. I suspect the hottest portion of your gas flame is in excess of 1000°C (http://en.wikipedia.org/wiki/Flame), but above that flame, it could be considerably less. I doubt the binder, which I am assuming is what burned, would actually burn at 600°, but it may vaporize. The risk from putting a big chunk in an industrial oven would be an explosion. That is, anytime you have combustion in an enclosed space there is that risk. I might try one of those inexpensive propane or butane burners that are quite popular. A plane plumber's torch might work or a butane one like this:



What are the overall dimensions of this thing?

John