Old germanium transistors, A health risk?...

[Jeff Liebermann]

On Fri, 23 Oct 2020 21:10:10 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

albert wrote:

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

Is it really BeO, or just pink alumina ceramics?
Best regards, Piotr

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 jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Gerhard Hoffmann]

Am 23.10.20 um 23:40 schrieb Jeff Liebermann:

On Fri, 23 Oct 2020 21:10:10 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

albert wrote:

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

Is it really BeO, or just pink alumina ceramics?
Best regards, Piotr

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.

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

 

[Phil Hobbs]

On 2020-10-23 13:35, Steve Wilson wrote:

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-10-22 19:01, Steve Wilson wrote:

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

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

How much better than mineral oil?

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.

Where do you get it? Amazon has an ointment that is 20% Dimethicone
plus a bunch of other stuff not needed for heatsinks.

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

Cheers

Phil Hobbs

Mineral oil is very similar to Dimethicone.

Thermal conductivity (W/mK):

Air : 0.024
Dimethicone : 0.15
Mineral Oil : 0.136

Vapour pressure not listed, of course.

<snip>

I have removed the CPU\'s from three computers that used mineral oil for
over a year. There was complete uniformity in the distribution (it
covered the entire surface of the CPU), and no evidence of evaporation.

A year isn\'t very long, and I doubt that you measured the bond line
before disassembly, so although you\'re no doubt correct that there were
no voids, that\'s different from being uniform.

Fancy modern TIMs can have problems with washout, where under thermal
cycling fine particles get washed out of the stacks of filler flakes
over time, dramatically increasing the thermal resistance.

Voids also form under thermal cycling, which is common in servers as
cores get switched on and off. Thermal expansion pushes the TIM out
when it\'s heated, but there\'s nothing to pull it back in when the
temperature goes down again. High performance heat sinks have
reservoirs of TIM, so it can flow in both directions without getting lost.

Cheers

Phil Hobbs

(Who used to work in the Packaging Research department at IBM Watson,
and so got to help out with some of these sorts of things, and heard a
lot more at talks and group meetings. Don\'t get me started on lead-free
solder.)

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Piotr Wyderski]

Jeff Liebermann wrote:

> Pink ceramic contains beryllium.

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

However, if there really was
beryllium in white ceramic, I would expect to see hazardous material
warnings and disposal instructions accompanying the equipment.

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

 

[Steve Wilson]

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-10-23 13:35, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
Vapour pressure not listed, of course.

I did an extensive search to try to find the vapour pressure of mineral
oil and dimethicone.

Vapour pressure is a can of worms. It depends on the grade and
application, and can vary from mineral oil used in high vacuum pumps to
dimethicone used in women\'s makeup powder.

Just to show you I\'m not lying, here are some of the searches I did:

<http://dept.harpercollege.edu/chemistry/msds1/Mineral%20oil%
20ScienceLab.pdf>

<http://www.clearcoproducts.com/pdf/cosmetic/dimethicones/PSF-5cSt.pdf>

<http://www.inchem.org/documents/icsc/icsc/eics1597.htm>

<http://www.lindberg-lund.fi/files/Tekniske%20datablad/DC-200-TD.pdf>

<http://www.scientificspectator.com/documents/Olenick%20Compilation/Ch%
2026%20D5.pdf>

<https://ca.vwr.com/assetsvc/asset/en_CA/id/10575382/contents>

<https://download.atlantis-press.com/article/25901316.pdf>

<https://echa.europa.eu/registration-dossier/-/registered-
dossier/15514/4/7>

<https://nvlpubs.nist.gov/nistpubs/jres/35/jresv35n3p219_A1b.pdf>

<https://shop.kremerpigments.com/media/pdf/87081e.pdf>

<https://ww3.arb.ca.gov/db/solvents/solvent_pages/hydrocarbon-
html/mineral_oil.htm>

<https://www.brb-international.com/uploads/markets/analysis-of-volatile-
dimethicones-for-cosmetic-pc-mag-nov-2016.pdf>

<https://www.chemicalbook.com/ChemicalProductProperty_EN_CB0696472.htm>

<https://www.dow.com/content/dam/dcc/documents/en-
us/productdatasheet/95/95-5/95-514-xiameter-pmx-200-si-fluid.pdf?
iframe=true>

<https://www.essence-plus.com/essence-
plus689/program_download/good/201610111628081541.pdf>

<https://www.johnmorrisgroup.com/Content/Attachments/241939/POD_CP_120_18
_04_2019_2_EN.pdf>

<https://www.maritimebeautyshop.com/images/msds/REDK_FRIZZDISSM.PDF>

<https://www.sciencedirect.com/science/article/abs/pii/S0167892208700877>

<https://www.sciencedirect.com/science/article/abs/pii/S0167892208700889>

<https://www.sciencedirect.com/science/article/abs/pii/S0167892208700890>

<https://www.sciencedirect.com/science/article/abs/pii/S0167892208700907>

<https://www.shinetsusilicone-global.com/catalog/pdf/kf96_e.pdf>

<https://www.sonneborn.com/sites/default/files/pdf/msds/na/SDS_Sonneborn%
20RUDOL%20White%20Mineral%20Oil_092018.pdf>

<https://www.uvm.edu/~vgn/outreach/documents/MINERALOIL.pdf

I have removed the CPU\'s from three computers that used mineral oil
for over a year. There was complete uniformity in the distribution
(it covered the entire surface of the CPU), and no evidence of
evaporation.

A year isn\'t very long, and I doubt that you measured the bond line
before disassembly, so although you\'re no doubt correct that there
were no voids, that\'s different from being uniform.

I don\'t know what you mean by bond line. The mineral oil completely
covers the cpu. You can see the shiny surface on both the cpu and the
heat sink, and you can feel the slippery surface due to the mineral oil.

It is clear the mineral oil forms a very thin film that maintains contact
between the cpu and the heat sink.

Please note I do not use the wimpy heat sinks supplied by Intel. I use a
much better unit from Amazon, similar to this one:

Thermaltake CLP0556 CPU Cooler
<https://www.amazon.ca/Thermaltake-Cooling-Intel-CLP0556-B-
Black/dp/B002RWJGI6/>

This supplies considerable spring-loaded pressure to the heat sink. The
pressure is uniform from one heat sink to the next, and the mineral oil
is squeezed to a very thin film.

The distribution was complete and uniform.

Fancy modern TIMs can have problems with washout, where under thermal
cycling fine particles get washed out of the stacks of filler flakes
over time, dramatically increasing the thermal resistance.

Voids also form under thermal cycling, which is common in servers as
cores get switched on and off. Thermal expansion pushes the TIM out
when it\'s heated, but there\'s nothing to pull it back in when the
temperature goes down again. High performance heat sinks have
reservoirs of TIM, so it can flow in both directions without getting
lost.

I do not know what you mean by TIM. The heat sinks expand and contract
under thermal cycling. Mineral oil is an incompressible liquid, and it
maintains a very thin film that remains in contact with the cpu and heat
sink despite the expansion and contraction.

You said earlier that dimethicone was the product of choice. It is
impossible to get in the small quantities need for heatsinks. I use
Walmart grade mineral oil, and it works fine.

Note also that regular thermal paste dries out and needs to be replaced.
You see this when removing the heat sink on computers that have been in
service for a number of years.

The application of new paste depends on the skill of the user. Mineral
oil has no such problems.

I can monitor any evaporation of the mineral oil by checking the cpu
temperature with the watch -n 2 sensors in Ubuntu. The results using
mineral oil are very satisfactory.

Cheers

Phil Hobbs

(Who used to work in the Packaging Research department at IBM Watson,
and so got to help out with some of these sorts of things, and heard a
lot more at talks and group meetings. Don\'t get me started on
lead-free solder.)

--
Science teaches us to trust. - sw

 

[Martin Brown]

On 22/10/2020 22:43, Phil Hobbs wrote:

On 2020-10-22 13:33, Adrian Tuddenham wrote:
albert <albert@cherry.(none)> wrote:

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

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

Beryllium toxicity is much more slow acting than that unless you do
something incredibly stupid.

Beryllia melts at 2500C and boils at 3900C.  You\'d really have to put it
to the torch to have anything to worry about.

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

 

[Jeff Liebermann]

On Sat, 24 Oct 2020 00:15:18 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

Am 23.10.20 um 23:40 schrieb Jeff Liebermann:
On Fri, 23 Oct 2020 21:10:10 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

albert wrote:

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

Is it really BeO, or just pink alumina ceramics?
Best regards, Piotr

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.

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

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>
It wasn’t just the distinctive magenta pink color that
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 jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Sat, 24 Oct 2020 12:07:57 -0700, Jeff Liebermann <jeffl@cruzio.com>
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 jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[whit3rd]

On Friday, October 23, 2020 at 3:15:26 PM UTC-7, Gerhard Hoffmann wrote:

Am 23.10.20 um 23:40 schrieb Jeff Liebermann:

Pink ceramic contains beryllium. However, if there really was
beryllium in white ceramic, I would expect to see hazardous material
warnings ...

BeO is white, not pink, and as a sintered powder it would be
white ceramic also...

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>