Old germanium transistors, A health risk?

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In the 70's I bought some computer dump stuff, these were
boards with digital circuits with germanium transistors in
a metal housing, of size 2n2905.

I opened them and a white powder came out.
I hope it is not some berillium compound, but the best reason to have
something in there would be cooling, so that could make sense.
Normally I would think it would be a paste that dried out, but the can
is hermetically sealed.

What could that powder be?
(It can take decades to die from berillium poisoining so my
time is up.)

Groetjes Albert
--  
This is the first day of the end of your life.
It may not kill you, but it does make your weaker.
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Re: Old germanium transistors, A health risk?
On 2020-10-22 08:56, albert wrote:
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How much of it, and what does it look like?  Almost all white heatsink  
grease is made from zinc oxide, as used on babies' bottoms the world over.

The big beryllium scare was in the very early'50s, so I wouldn't expect  
beryllium oxide in heatsink grease from the transistor era.  (I've heard  
anecdotal reports, but it's all FOAF stuff.)

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Old germanium transistors, A health risk?
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About say 10% of the TO5 can.
What do you mean, what does white powder look like?

If it is zink oxide that is easy to check. ZnO turns yellow when heated.
I'll try and report back here, some time.

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Remember that these were not commodity items, possibly military.

There seems to be substantial BeO in micro waves, so industrial use
of Be has not totally ceased.


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Groetjes Albert
--  
This is the first day of the end of your life.
It may not kill you, but it does make your weaker.
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Re: Old germanium transistors, A health risk?

[...]
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If you heat it and are still alive to report back, we shall know it
wasn't Beryllium

--  
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
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Re: Old germanium transistors, A health risk?
Am 22.10.20 um 19:33 schrieb Adrian Tuddenham:
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It probably takes a very high temperature until gases develop.

But then, I found a box of 20 BFQ135 transistors this week when
sorting my parts inventory.

<  
https://www.flickr.com/photos/137684711@N07/50517364401/in/album-72157662535945536/
     >

A pinhead of the ceramic in the lung is pretty sure to give you
lung cancer. Well, it takes some time, maybe too long for me, but
the word "expiration date" gets a completely new meaning in the
context of lung cancer.

The transistors are nicely packed in a styro foam tablet, individually.

Cheers, Gerhard


Re: Old germanium transistors, A health risk?
On 22.10.20 21.44, Gerhard Hoffmann wrote:
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The beryllia is well hidden inside, it is between the chip and
the mounting stud. The ceramic seen outside is alumina.

--  

-TV


Re: Old germanium transistors, A health risk?
On 2020-10-22 13:33, Adrian Tuddenham wrote:
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Beryllia melts at 2500C and boils at 3900C.  You'd really have to put it  
to the torch to have anything to worry about.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Old germanium transistors, A health risk?
On 22/10/2020 22:43, Phil Hobbs wrote:
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Beryllium toxicity is much more slow acting than that unless you do  
something incredibly stupid.


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Trouble is as a fine dust it could end up in your lungs which is very  
bad. I'd treat all old power transistors as potentially dangerous  
inside. It is a powerful skin sensitiser for contact dermatitis too.

It is safe enough as large scale crystalline materials like emerald and  
aquamarine but as a fine ceramic dust it is really quite nasty.

Sharpening beryllium copper tools in oil refineries was seriously life  
shortening until they realised that beryllium in the dust was so toxic.

Various single crystals of pure beryllium metal around the world from  
the early days of X-ray crystallography have killed people in the past.  
The wounds from a scratch off it take almost forever to heal.

--  
Regards,
Martin Brown

Re: Old germanium transistors, A health risk?
On 2020-10-22 12:26, albert wrote:
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Solid chunks of BeO are pretty safe as long as you don't put a grinder  
on them--it's a hard refractory ceramic.  It's just the powder that's  
dangerous.

Cheers

Phil Hobbs


--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Old germanium transistors, A health risk?
albert wrote:

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Is it really BeO, or just pink alumina ceramics?

    Best regards, Piotr

Re: Old germanium transistors, A health risk?
On Fri, 23 Oct 2020 21:10:10 +0200, Piotr Wyderski

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Pink ceramic contains beryllium.  However, if there really was
beryllium in white ceramic, I would expect to see hazardous material
warnings and disposal instructions accompanying the equipment.  I
would also expect some issues with handling and recycling of microwave
ovens.

Note that beryllium and BeO are not listed on the RoHS banned list,
but might be added at some time in the future:
"RoHS Proposed Additional Substances Review"
<https://blog.complianceandrisks.com/commentary-analysis/rohs-proposed-additional-substances-review



--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Old germanium transistors, A health risk?
Am 23.10.20 um 23:40 schrieb Jeff Liebermann:
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BeO is white, not pink, and as a sintered powder it would be
white ceramic also. And on the box of the 20 BFQ139 transistors that
I yesterday took a photo from, the warning was much larger in print
than the number and type of transistors.

cheers, Gerhard

Re: Old germanium transistors, A health risk?
wrote:

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I stand corrected.  Not all pink ceramic contains beryllium.

Hopefully you're not referring to the ceramic covers over the
transistor die, which are probably alumina and do not contain
beryllium because they do not require superior heat transfer.  The
area that needs the best heat transfer is between the semiconductor
die and the screw or flange mounting base.  For example, the "ceramic
substrate" in this drawing might be a suitable candidate for BeO:
<https://www.semanticscholar.org/paper/Modeling-techniques-suitable-for-CAD-based-design-Aaen-Pla/e62509a9d37e0b284a783d35d13bbad92fcb19b8/figure/0

At least one ceramic major supplier uses pink (probably from chromium
doping) as either their trademark or possibly as a means of
recognizing that the ceramic contains beryllium.  From 1998:
<https://yarchive.net/electr/beryllia_insulators.html
   Beryllium oxide is normally white.  I have never seen it in  
   pink, although it may have been produced that way for some  
   special application.  Many electrical insulators made by  
   Heany Ceramics are pink.  In fact, this is their trademark  
   color.  I think most of these are Alsimag ceramics though.

<http://www.heany.com

   made our ceramics stand out from the rest.  

BeO Still A Force In RF Power Transistor Packaging  
<https://materion.com/-/media/files/ceramics/articles/beo-still-a-force-in-rf-power-transistor-packaging.pdf

BeO Takes The Heat In RF Transistor Packages
<https://www.mwrf.com/materials/article/21843703/beo-takes-the-heat-in-rf-transistor-packages

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Old germanium transistors, A health risk?
wrote:
(...)
Yet another beryllium hazard.

"Potential Beryllium Contamination due to Wear of Beryllium/Copper
Finger Stock Used for Radio-frequency Shielding"
<https://opexshare.doe.gov/lesson.cfm/2014/7/7/4355/Potential-Beryllium-Contamination-due-to-Wear-of-BerylliumCopper-Finger-Stock-Used-for-Radio-frenquency-Shielding

I used quite a bit of finger stock while building several RF screen
rooms and for RF shielding various radios.  I cut myself in the leg on
a sharp edge during one build.  I don't recall if it was from the
copper sheathing, beryllium-copper finger stock, or something else
like a copper plated nail.  The cut healed normally.  If I'd known
that I was risking my life, I probably would have asked for hazard pay
or a salary increase.  

Drivel:  Beryllium-copper finger stock is quite springy.  We installed
some on a radio burn-in room around the door frame, similar to what is
shown in the article.  Before I could stop them, someone slammed the
door shut to see if everything fit.  It fit, but we couldn't get the
door open again by pulling on the door handle.  I eventually opened
the door by climbing through ceiling fan duct and kicking the door
open from the inside.


--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Old germanium transistors, A health risk?
On Friday, October 23, 2020 at 3:15:26 PM UTC-7, Gerhard Hoffmann wrote:
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Alumina is also white, unless chromium-doped (and that turns it pink).
BeO is tagged with an odd color (I've seen purple, and pink) as a
warning, not because that is its natural color.

This is a microwave oven tube example
<
http://i44.photobucket.com/albums/f13/civon68/scrapforum/household/microk_zpse5a01498.jpg


Re: Old germanium transistors, A health risk?
Jeff Liebermann wrote:

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Not necessarily, Cr-doped Al2O3 looks like that as well.

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This is one thing. But I believe that the primary requirement for a  
general-purpose magnetron is "cheap". The second is most likely "cheap"  
as well. BeO technology is way too expensive.

    Best regards, Piotr

Re: Old germanium transistors, A health risk?

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Penaten. Zinc Oxide. 110 years of service. Good for bedsores from  
hospital stays. Almost useless for anything else.

https://www.penaten.ca/

Heatsink grease often dries out. I notice this from salvaging CPUs from  
older computers. IBM used to have huge heat dissipation problems on their  
mainframes, but an extensive search doesn't reveal what they used for  
their thermal grease.

I have switched to using mineral oil. It fills all the gaps and is less  
likey to evaporate. So far it is working fine.

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--  
Science teaches us to trust. - sw

Re: Old germanium transistors, A health risk?
On 2020-10-22 12:31, Steve Wilson wrote:
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You're obviously not a dad. ;)  Zinc oxide ointment (Desitin by  
preference) fixes diaper rash right up.

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TCMs don't use grease.  When I left IBM about a dozen years ago, they  
were using some Shin Etsu paste with about 3 W/m/K conductivity.

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Polydimethylsiloxane (Dimethicone) is the liquid of choice.  Non-toxic,  
very low vapour pressure.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Old germanium transistors, A health risk?

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Two kids. I included diaper rash as the primary useage.  
  
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Sorry. I thought grease and paste meant the same thing when applied to  
heatsinks.
  
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How much better than mineral oil?

Where do you get it? Amazon has an ointment that is 20% Dimethicone plus  
a bunch of other stuff not needed for heatsinks.
  
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--  
Science teaches us to trust. - sw

Re: Old germanium transistors, A health risk?
On 2020-10-22 19:01, Steve Wilson wrote:
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TCMs initially used helium gas, then switched to oil.  They never used  
paste or grease.

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Dunno exactly, but it varies by viscosity.  The carbon or silicon  
dominates the molecular weight, whereas the hydrogen dominates the van  
der Waals forces, so for the same chain length I'd expect the vapour  
pressure to be much lower.

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BITD I ordered it from Clearco--about $70 per gallon, if you need that  
much. ;)

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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