# Old Transistors? Containing white paste?



## Syn (Dec 18, 2018)

Okay i cracked some old transistors (metal case package types, me bn silly forgetting the exact name..) in a sealed container (expecting BeO at worst) when i came across some weird ones.
Instead of a solid they contain a white paste, almost like toothpaste.. what could it be?


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## archeonist (Dec 21, 2018)

If you expect BeO, why would you crack it open? No idea what the paste is.


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## henos (Dec 22, 2018)

Silicone paste for heat dissipation


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## macfixer01 (Dec 22, 2018)

henos said:


> Silicone paste for heat dissipation




Beryllium is usually used in electronics as a hard ceramic material for substrates or the bodies of high power microwave components for example. Regarding filled transistors though; I have some with an ordinary grayish translucent silicone paste inside, some with white silicone paste, and some with white powder. My suspicion is that the white color paste is from the addition of zinc oxide, similar to the heatsink compound made by Corning. I believe the white powder is also just zinc oxide. I’ve been reluctant to do anything with them though, since some people have said it could be beryllium oxide? Although it’s really hard to get an accurate price since there is no spot market for it, from various internet sources it appears beryllium metal costs somewhere in the $200-$350 per pound range. So which is it more likely to be based on economics alone? Zinc oxide at a little over $1 per pound, or beryllium oxide at potentially as much as 300 times the cost?

If someone who understands Russian would be willing to take a look at this 5 minute video, this guy cuts open some of the transistors containing white powder. I’d like to know what conclusions he came up with?

[youtube]https://youtu.be/dtCMnKfUJRc[/youtube]

Thanks,
Macfixer01


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## stella polaris (Dec 23, 2018)

@Macfixer

He do not know why its there or what it is. He ask the viwers what it is... So that was a dead end.

The film that followed was intresting. Sovjet and import capacitators with silverbody. https://www.youtube.com/watch?v=0cza3u-tJNw


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## g_axelsson (Dec 23, 2018)

stella polaris said:


> The film that followed was intresting. Sovjet and import capacitators with silverbody. https://www.youtube.com/watch?v=0cza3u-tJNw


Tantalum capacitor.

Göran


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## stella polaris (Dec 23, 2018)

g_axelsson said:


> stella polaris said:
> 
> 
> > The film that followed was intresting. Sovjet and import capacitators with silverbody. https://www.youtube.com/watch?v=0cza3u-tJNw
> ...



Yes. But they are discussing the bodies. The ones he melts are of silver.


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## stella polaris (Dec 23, 2018)

@Göran

How good were actually Sovjet components? Technical vice.


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## g_axelsson (Dec 23, 2018)

stella polaris said:


> g_axelsson said:
> 
> 
> > stella polaris said:
> ...


Yes, that are the wet type of tantalum capacitor. It was also made in the west with massive silver body and has been discussed a lot. I've rarely seen them myself and never refined them.

I have no experience of Russian components and how they compare to western parts. There are a couple of members from east who have discussed components over the years and who could probably answer your questions.

Göran


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## Syn (Dec 24, 2018)

Thanks for the answers!

I cracked it open to be sure.

So whats a good way to remove this paste?


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## macfixer01 (Dec 24, 2018)

Syn said:


> Thanks for the answers!
> 
> I cracked it open to be sure.
> 
> So whats a good way to remove this paste?





I asked that question here before, and someone suggested (after removing the caps) boiling them in hot water. That sounded reasonable.


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## macfixer01 (Dec 24, 2018)

stella polaris said:


> @Macfixer
> 
> He do not know why its there or what it is. He ask the viwers what it is... So that was a dead end.
> 
> The film that followed was intresting. Sovjet and import capacitators with silverbody. https://www.youtube.com/watch?v=0cza3u-tJNw




Thank you Stella Polaris!


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## TantalumRecyclingFL (Jan 7, 2019)

These are Western Tantalum Silver Capacitors.


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## Syn (Feb 4, 2019)

Do these kinda transistors have gold solder? I saw a video on youtube where the caps have been removed (and most likely went to random scrap) without processing, is this really the correct way?


Above post is completely off-topic, please remove it.


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## FrugalRefiner (Feb 4, 2019)

Syn said:


> Above post is completely off-topic, please remove it.



Syn, the post above yours is on-topic.


g_axelsson said:


> stella polaris said:
> 
> 
> > Yes. But they are discussing the bodies. The ones he melts are of silver.
> ...


TantalumRecyclingFL is showing the silver bodied capacitors stella polaris and Göran discussed a few posts above.

Dave


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