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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Im looking into a small device like a conventional "black-box" for airlines, which would survive a short fire and brief battery explosion. But given a typical RFID tags and conventional ICs, is there a material known to any forum member that maybe suitable? I was thinking of pouring a RTV or similar compound into a mould, with fireplace mineral wool.
The wire harness can burn off i plan to use RFID and other RF removal of data.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
Ash Small wrote ...
How heavy is this going to be?
What's wrong with a radio link, for example? You'd get the same data for less weight, surely?
Just my two cents worth
You want to know why it crashed and that is not always possible with a radio link, since the link may be the cause or fail for the same reason that crashed it.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
but its more thermal insulation i need. Transistor dont work well at 400 degrees Fahrenheit. i need the outside of the device to be on fire but the inside still survivable.
sigh, i went brain non-functional when posting this thread. I was meaning intumescent fire stop type caulk or epoxy.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
With such a tiny internal volume (small C), and thin layer of insulation (small R), your RC time constant for heating up the inside will be very small, a sausage cooks inside far faster than a turkey in an oven for instance.
If you want to keep the inside cool, then an off the wall light and passive way is evaporative cooling. If your electronics will operate at (say) 100C, and using milspec components and some care there's no reason why not, then consider this. Have some water in the protected cavity, allow it to vent non-destructively to the outside when it boils, and you can mop up a lot of heat for little mass. You could even provide the cheap '10 second' survival module, and the premium '5 minute' module, the only difference being whether they were water filled. Other fluids might be more compatible with electronics, but it's hard to beat water for heat capacity, latent heat of boiling, flammability, bio-hazard, cost, and boiling at a reasonable temperature. It doesn't have to flood the active components necessarily, I doubt a conformal coating would withstand years of immersion, it could simply be in a void attached to a heatsink in contact with the board back surface.
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Question Regarding Fire Surviving of Circuit Boards.
