white powder in TO3-transistor?

[solar_plasma]

When I opened an old heavily goldplated TO3, I found a white powder in it. My first guess was asbest?! Could not be since asbest is a themal isolator...d.mn...Berlliumoxide?! Now I've read on the german wiki that BeO often is replaced by aluminium nitride or boron nitride as a thermal bridge because of BeO's poisoness. Now, the transistors may be 30 or 40 years old.

If it is AlN it would slowly solute in water forming NH3, BeO definately not ...ok that would be easy

BN and BeO ...no idea yet, any suggestions?

Would like to know, if I have to dispose it as toxical waste or if I can get the gold inside without greater harms.

Would be really nice if someone could help.Thanks! ...and thanks for this phantastic forum, cant stop reading all your experiences, problems and smart solutions!

 

[butcher]

I do not know what you have there, but they use silica sand in industrial fuses called electrical fuse sand, I wonder if that is what you are looking at?

 

[solar_plasma]

this would be a third posibility. But i think it's a really bad idea to test with concentrated H2SO4, HCL, HNO3 if the powder is soluable in it, without knowing, what it is. Think it would be a flouride...lol..hooray! Could be everything. A thermal bridge would just be logical for a heavy duty radio or amplifier component. Maybe with a few milligrams under a fume hood?!

you know what...this is a quite dangerous hobby! LOL

Edit: I've found the answer: http://www.chemgapedia.de/vsengine/...te/erdalkalimetalle/beryllium/be02.vscml.html

Thank you for helping me thinking! Further suggestions are nevertheless welcome.

 

[butcher]

that looked like a test for beryllium oxide, but then again I cannot read that language, but the formula looked familiar.
Did the article say that is what they used in transistors?

 

[solar_plasma]

Sorry, unpolite of me, not to explain it.

Well, they say, beryllium ions will preticipate with NH4OH or NaOH and form beryllium hydroxide as a white gel slime which goes in solution again with acids. 'Although with conc. NaOH, but not if there is NH3 in the solution. As BeO forms solutable BeSO4 with conc H2SO4, this would be the way to determine the existence of beryllium.

I dont know why, but when you said "silica sands", I got the idea where to look it up, because thats the next step for me before I add conc acids to anything :lol:

I will add the results as soon as I ve got the time to do this little "analysis"

 

[butcher]

Beryllium dissolves readily in non-Oxidizing acid, such as HCl and dilute H2SO4, but not in nitric acid or water as this forms the oxide.[

Many metals will dissolve in these acids and many in a caustic solutions, I would look for a better way to test for beryllium.

http://www.minsocam.org/ammin/AM31/AM31_82.pdf

Be very careful transistors can have arsenic, as well as beryllium which I thought would be part of the metal in the die and not a sand type substance, germanium, beryllium, copper, gold, silver, arsenide, silicon. Aluminum, gallium, and other metals have been used or could be involved.

 

[solar_plasma]

arsenic too...didnt want my gold to smell like garlic....ok, if I want to do it right, I should do a systematic cation splitting (dont know the correct english word) of the hole transistor, in order to avoid getting funny poison gas and a really bad day (AsH3: LC 20mg/m3).....really bad! Or completely leave it. Last one sounds better.

 

[solar_plasma]

Okay I've found the answer:

YES there is sometimes beryllium oxide powder inside TO3-cans (bipolar transistors)! Very poisonous,very ugly! Much worse than asbestos!

Source: http://www.vintage-radio.net/forum/showthread.php?t=25577
(post #8 and #9)

 

[Long Shot]

Butcher - hint, right click, translate to English.

Edit: If using Google Chrome, not sure about other browsers.

 

[GotTheBug]

Bipolar Transistor, I married one of those once, and yes they can very dangerous indeed!

 

[72chevel]

Thanks for bringing this up! I have dozens of these parts from an organ I tore apart and they all had that white compound in them. I only broke one open to see the gold inside looked like harmless powder but now I know!

 

[Lou]

Could also be barium titanate. Which is poisonous.

 

[72chevel]

When I got home from work I told my Wife about how bad this white powder could be for you. She then reminded me how when I broke one open and dumped it out on the kitchen table I acted like I snorted a line of it :lol:

 

[g_axelsson]

Could also be barium titanate. Which is poisonous.

Are you sure about it? I haven't seen any references to barium titanate as a thermal paste. It is also not that soluble except in acids and it's one of the more commonly used ceramics in MLCC:s.

Göran

 

[Lou]

I know it's in MLCCs.

I know nothing about transistors, so consider me a keen member of the peanut gallery.

Lou

 

[macfixer01]

I know it's in MLCCs.

I know nothing about transistors, so consider me a keen member of the peanut gallery.

Lou

Barium compounds will impart a green color to a flame. Beryllium either doesn't impart any definite color, or perhaps imparts a color not within our visual range.