4000g assembly 1

[MarkUMSU]

I'm working to design a small (~8mm cube, <12grams) electronics package and assembly that can live in an environment with vibration producing accelerations up to 4000g at ~ 100Hz.

Does anyone know if anything like this have ever been done before? The most robust assembly I've found is munitions guidance systems package, but they're not built for fatigue, and helpful details have been hard to find.

I would appreciate any other tips (ranging from preferred IC connection, to robust solder compounds, potting, PWB materials, and anything else) on how to keep this from falling apart.

One other thing. Since I'm trying to measure the vibration, absorbers and isolators are not very attractive options.
MB

 

[MikeHalloran]

Just off the top of my head, I doubt that a _wire_ can survive that environment. That includes the lead wires in IC packages, so you may have to work directly with dice, and use mechanical contacts for interconnect, with the whole thing sort of sandwiched together between backing plates linked with screws.

But that still leaves two questions; how do you get the energy in and the signal out?



Mike Halloran
Pembroke Pines, FL, USA

 

[tomirvine]

4000 G at 100 Hz is well above any vibration specification that I have ever encountered.

Did you mean that the 4000 G at 100 Hz is from a shock response spectrum? This level would even be extraordinarily high even for a shock response spectrum.

You could try Steinberg's Vibration Analysis for Electronic Equipment book, available from:

http://www.amazon.com/exec/obidos/ASIN/047137685X/vibrationdata-20

Tom Irvine

 

[GregLocock]

http://www.bksv.com/3889.asp?s=pC/m...1S:4374S:4375S:4384S:4393S:4384V:4393V:4374L:

Are all electronic systems that will survive in that environment. Quite how you are expected to fasten leads to them is another question. Ask them.

As you say projectiles are the best source of prior art. If they can make vacuum tubes that survive in a shell, I don't think you are asking much to do the same with solid state.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[IRstuff]

There are cannon-launched projectiles that supposedly can handle 100,000 g loads

TTFN

 

[MarkUMSU]

Thanks for the tips with the book and website. I've seen Steinberg's book mentioned several times on this site, so I guess it is time to get a copy....

As far as the high magnitudes, I have FEA and experimental data with periodic but not sinusoidal accelerations up to 2300G. I expect that in less ideal conditions the values will exceed these levels.

You're right about wire's breaking on their own at this level. I've seen copper break after less than a day of testing, but a kapton backing seems to help.

By the way Mike, I grew up in P.Pines, FL.

 

[MikeHalloran]

I live a few blocks from the first City Hall, East of the airport. That's evolved, but still a nice neighborhood. The rest, especially the Quantum Shopping Centers, I could do without.



Mike Halloran
Pembroke Pines, FL, USA