Ceramic heat spreaders

On Mon, 18 Apr 2016 06:03:01 -0700 (PDT), Phil Allison Gave us:

Modern smart phone (or not so smart) texting days, these are.

so.... 2 stupid.

Yet another thread poisoned by DecadentAlwaysWrong.

Yup. The vertical temperature gradient varies a lot from place to place. IIRC Saudi's is gentle, so you're working at a relatively mild

70C or something down there, but in other spots like West Texas it's a lot hotter. 175C is a commonly-quoted worst case number.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

What makes you think it is BeO? I do have some RF signal generators with BeO insulated output devices but I know this because of copious warning labels inside the case and in the manual. These days, bearing in mind the health and safety precautions that would be expected in Western countries, I would be quite surprised if this stuff is used anywhere outside of avionic and military and high-end test equipment.

There are persistent rumours that the insulators on home microwave oven magnetrons are BeO also, but I have no reason to believe that this has been true except perhaps for the very earliest ones.

Chris

Phil Hobbs wrote his usual OT crap.

** The importance of remaining in context holds no value in your world - does it Phil ?

.... Phil

BeO is a strong refractory ceramic, so there's no reason to be scared of it unless it's been reduced to powder. I wouldn't want to grind it, but using a BeO insulator would cause me zero concern.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Specifying 177'C is usual as it's a round 350'F and oil stuff is generally US led - so oven testing at 180'C is common.

Hotter is possible but difficult and (even more) expensive. Sometimes vacuum flasks are used to keep stuff cool enough for long enough, but any delays and you end up with a flask full of desoldered components.

Cheers

--
Syd

Syd is the OP, Phil, and he doesn't seem to think it's OT. Speaking of context, if you'd been paying attention all these years, you'd know that Syd does downhole stuff for a living.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

I had a downhole gig five years or so ago--I was spending a week per month in Albuquerque NM working with a geophysical sensors outfit called Symphony Acoustics. (Yes, they started out making interferometric microphones.) At the time, they had a big contract with Baker Hughes to do downhole gravimeters for rock density measurements.

That's where I did the super-stable laser I was talking about on the miniaturization thread just lately.

I tried really hard to get B-H to let us do a thermoacoustic fridge for them. A TA fridge is just a piece of stainless steel tubing with a heater at one end, a cold plate at the other, and a bundle of copper and ceramic tube in the middle, connected to the heat sink. You heat one end and the other end gets cold. (Of course you have to pull the heat back out in the middle.) All metal and strong ceramic, no moving parts, so it should easily survive being chucked in the back of a truck and bounced along to the next well.

It would have provided a nice 25C ambient for all sorts of measurements. However (besides putting a crimp in your nice lucrative replacement business) it ran afoul of the lore of the oil services oldtimers, which is that flasks are OK but fridges aren't.

A pity.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Are they bipolars or mosfets?

Mosfets seem to turn on hard at about 300C, but recover when cooled. The ones I tried failed permanently at 330C, but they were plastic parts and the failure may have been a package problem.

We do need affordable bulk diamond. And room temp superconductors. I wish those condensed-matter dudes would get going.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics

Nah, there are superconductors that work up to a balmy 120K or so. You just need to turn up the A/C a bit. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

** You have no idea what Syd thinks - or if he does.

** Go wash your mouth out.

** Syd is liar, a jerk and a troll.

Bet he does stuff all for a living.

.... Phil

You're just jealous because your audio stuff doesn't fit down a 3-inch cased well. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Phil Hobbs wrote even more of his usual OT crap.

** You are not one bit funny - just pathetic troll feeder.

FOAD.

.... Phil

Yes, I recall you mentioning that before. Did you mean a _speaker_ at one end?

I wonder how long it would need to be if it were to fit inside, say, a

1" ID housing? Even just losing 50'C can bring a whole lot of parts and sensors back into play. Does the speaker have to be at the hot end?

Cheers

--
Syd

You can do it that way, but you get much higher acoustic power with no movi ng parts with a heater. Just a regular 500W-ish Chromalox element will do f ine. Less efficient, but that doesn't matter much in this application.

Ours was going to be about 5 feet long, and sized for a 2-inch cased hole (

38 mm OD).

If you have an interested customer, give me a shout.

Cheers

Phil Hobbs

** The fact that they appear to conduct heat as well or better than aluminium.

** Really ?

BeO is perfectly safe to handle.

** Really ?

Lots of things seem to surprise you.

... Phil

On Mon, 18 Apr 2016 23:59:26 +1000, Chris Jones Gave us:

The industry has traditionally and typically used purple (violet) as the color for items made from this material.

I'll be happier when Coilcraft is making surface-mount perfectly shielded zero-resistance inductors from superconductive litz wire.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics