Hello,
I have a C128 that will ultimately be contained in an enclosure and attached to
an engine. There are several things to consider here, but I am curious about the
vibrations at this point. The C128 is on a board from www.axman.com, and there
are no moving parts.
Does anyone have any knowledge on the vibration limitations of a
microcontroller?
Vibration limitations of microcontrollers? C128.
Started by ●January 2, 2009
Reply by ●January 4, 20092009-01-04
I'm no expert on this topic but I doubt there are vibration limits
within the chip package itself that should concern you. I think
vibration would have a greater effect on the attachment of the chip to
the board. I once heard that pcbs for missiles required through-hole
chips with solder on both sides to minimize the effects of vibration.
As long as you use an adequate amount of solder, the board doesn't flex
much and you stay within the rated operating temperature you should be fine.
Also see here:
http://acqp2.nasa.gov/LFS%20Reliability/Solder%20Comparison%20by%20Component%20Level%20Life_Use%20%20Analysis_Final.pdf
More reason to stick with lead solder if RoHS conformance isn't necessary.
-rob
> Hello,
>
> I have a C128 that will ultimately be contained in an enclosure and
> attached to an engine. There are several things to consider here, but I
> am curious about the vibrations at this point. The C128 is on a board
> from www.axman.com, and there are no moving parts.
>
> Does anyone have any knowledge on the vibration limitations of a
> microcontroller?
within the chip package itself that should concern you. I think
vibration would have a greater effect on the attachment of the chip to
the board. I once heard that pcbs for missiles required through-hole
chips with solder on both sides to minimize the effects of vibration.
As long as you use an adequate amount of solder, the board doesn't flex
much and you stay within the rated operating temperature you should be fine.
Also see here:
http://acqp2.nasa.gov/LFS%20Reliability/Solder%20Comparison%20by%20Component%20Level%20Life_Use%20%20Analysis_Final.pdf
More reason to stick with lead solder if RoHS conformance isn't necessary.
-rob
> Hello,
>
> I have a C128 that will ultimately be contained in an enclosure and
> attached to an engine. There are several things to consider here, but I
> am curious about the vibrations at this point. The C128 is on a board
> from www.axman.com, and there are no moving parts.
>
> Does anyone have any knowledge on the vibration limitations of a
> microcontroller?
Reply by ●January 4, 20092009-01-04
At 09:32 AM 1/4/2009 -0500, you wrote:
>I once heard that pcbs for missiles required through-hole
>chips with solder on both sides to minimize the effects of vibration.
It helps. But the other big reason for through-hole mount is the
thermal coefficient of expansion (Tce). Military usually requires
ceramic carriers for their high-rel IC's. Mount the larger ones
directly on the G10 fiberglass board without the usual leads (for
example, ball grid or PLCC) and run a few cycles from -55 to +125
C. The IC will rip the solder pads right off the board.
> > I have a C128 that will ultimately be contained in an enclosure and
> > attached to an engine....
> >
> > Does anyone have any knowledge on the vibration limitations of a
> > microcontroller?
The biggest concern with vibration on an engine is the Q at the
resonant frequency of the PCB. A relatively low vibration of just a
few G's can be amplified into the dozens or even hundreds of
G's. Again, the IC's can come right off the board.
Worst case, you may need to do some testing (sweep the board over a
frequency range). Or otherwise, just put some vibration dampening
foam on the board to drop the resonance.
jmk
jmk
-----------
James M. Knox
TriSoft ph 512-385-0316
1300 Koenig Lane West fax 512-371-5716
Suite 200
Austin, Tx 78756 j...@trisoft.com
-----------
>I once heard that pcbs for missiles required through-hole
>chips with solder on both sides to minimize the effects of vibration.
It helps. But the other big reason for through-hole mount is the
thermal coefficient of expansion (Tce). Military usually requires
ceramic carriers for their high-rel IC's. Mount the larger ones
directly on the G10 fiberglass board without the usual leads (for
example, ball grid or PLCC) and run a few cycles from -55 to +125
C. The IC will rip the solder pads right off the board.
> > I have a C128 that will ultimately be contained in an enclosure and
> > attached to an engine....
> >
> > Does anyone have any knowledge on the vibration limitations of a
> > microcontroller?
The biggest concern with vibration on an engine is the Q at the
resonant frequency of the PCB. A relatively low vibration of just a
few G's can be amplified into the dozens or even hundreds of
G's. Again, the IC's can come right off the board.
Worst case, you may need to do some testing (sweep the board over a
frequency range). Or otherwise, just put some vibration dampening
foam on the board to drop the resonance.
jmk
jmk
-----------
James M. Knox
TriSoft ph 512-385-0316
1300 Koenig Lane West fax 512-371-5716
Suite 200
Austin, Tx 78756 j...@trisoft.com
-----------
