MRF137 does it contain BeO

Does the MRF137 contain any beryllium oxide?
In the datasheets it is not specified

I think if is not mentioned in the datasheet, the product already shifted the insulation material from beryllium oxide to aluminum oxide.
Aluminum oxide is not toxic, but have double of thermal resistance compared to beryllium oxide, which is the best insulation thermal material.

vfone said:

I think if is not mentioned in the datasheet, the product already shifted the insulation material from beryllium oxide to aluminum oxide.
Aluminum oxide is not toxic, but have double of thermal resistance compared to beryllium oxide, which is the best insulation thermal material.

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I have contacted macom.
It's base sits on 99.5% BeO.
Thanks anyway

They should write this in the datasheet, like many other manufacturers. As I know, in US beryllium oxide is not considered dangerous waste, even if this material is very toxic for humans. In Europe I think are different rules in this matter.

vfone said:

They should write this in the datasheet, like many other manufacturers. As I know, in US beryllium oxide is not considered dangerous waste, even if this material is very toxic for humans. In Europe I think are different rules in this matter.

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It is a pitty they don't write it down. Either it is a marketing trick so as these products are not considered dangerous, or they just don't think that it is possible to break them. I do not have to repeat the health issues if such transistors accidentally brake (although it is not very easy to do so, especially with the 211-07 package.

I remember phillips datasheets write such things down. Also all the articles I have seen about UHF TV amplifiers, write down this aspect regarding these transistors. Almost all the good designs I have seen that use RF power transistrors/mosfets in this package, designed for class-A operation, seem to contain this material.

A few decades before, I remember playing around with some BLY89 in FM transmitters and at least one of them has been broken from exessive screwing to the heatsink. This device does contain BeO and specified in bold letters in the Phillips datasheet. Back then we were young and no one knew or paying attention on these things. We were messing around with lead-based solder, not washing out hands, touching Hg and having fun with it, or breaking such transistors. Thank god, my lungs seem to be healthy after all these years, maybe the BeO disc was not damaged, eventhough the ceramic package has been broken.

Like me back then, kids may be playing around with these things in KITs, It is just not fair to judge them as safe.

I wonder it the plastic transistors, like the 2sc2166 do contain such substances, but due to the difficulty of braking these packages down, it is not mentioned in the datasheets?

having been one who stuck a BEO substrate into my finger once....and lived to tell the tale....BeO is only toxic to humans if you grind it up and inhale the dust. So if you are just going to throw it away in a landfill, yes it is NOT considered toxic waste in the USA.

biff44 said:

having been one who stuck a BEO substrate into my finger once....and lived to tell the tale....BeO is only toxic to humans if you grind it up and inhale the dust. So if you are just going to throw it away in a landfill, yes it is NOT considered toxic waste in the USA.

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What happens when you break a transistor that contains BeO? Does it certainly contaminate, or it does so only if the base is damaged (tiny particles that come into your lungs)?

Also is anyone aware if these plastic power transistors like 2sc2166 and 2sc1969 contain such substance?

I assume that only high power transistors (>25W) which needs very low thermal resistance use BeO.
Of course, only if you open a transistor case AND scratch the substrate could be the BeO dangerous for your health. I remember that many years ago (when I didn't have any clue about this issue), I opened few damaged high power RF BJT's to check them at the microscope, just for educational purpose. And I am still alive.

some microwave tubes also contain BeO

biff44 said:

some microwave tubes also contain BeO

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Interesting, Do you refer to the UHF ceramic tubes, the lighthouse type tubes, magnetrons, klystrons or TWT amp tubes?

neazoi said:

What happens when you break a transistor that contains BeO? Does it certainly contaminate, or it does so only if the base is damaged (tiny particles that come into your lungs)?

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Security datasheets says that it is dangerous only if you damage it mechanically (respirable particles) or by heat (vapor).

volker@muehlhaus said:

Security datasheets says that it is dangerous only if you damage it mechanically (respirable particles) or by heat (vapor).

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Yes of course, the problem is that if you manage to break the base of such a transistor, it almost certainly leads to small BeO dust (small amounts) on the air, at least at the instant you break it. And since you will not do that in a ventilated area, unless you work on a pro lab, it is likely that any homebrew guy would be likely contaminated.
All the above, is IF you manage to break the base, which normally sits on the BeO insulation layer.
As already mentioned, at least two guys on this thread (including me) seem to have "survived" by such a break.

neazoi said:

the problem is that if you manage to break the base of such a transistor, it almost certainly leads to small BeO dust (small amounts) on the air, at least at the instant you break it.

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Sure, if you break many transistors and then start pulverizing the pieces again and again, you need to worry.
The security datasheets mentions "large dosage that doesn't exist in today's work environments".

neazoi said:

As already mentioned, at least two guys on this thread (including me) seem to have "survived" by such a break.

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Effects can be both toxic and long term (cancer). So don't start drilling holes into BeO transistor basis every day :-D