Homebrew PCBs

Steve is exactly right here.
A lot of my boards go on small engines the vibration is very bad.
I learned the hard way on the first few. You will find that the 
IC chips will not be hurt because they are low to board but the
solder joints will be weakened or crack if not perfect. The biggest
problem occurs with Capacitors or Transistors that are mounted straight
up. The amount of mass and distance from the board caused the leads
to break when the harmonics begin.

What I use is an encapsulating compound it does 3 major things
Transfers vibration and stress
Dissipates heat from components
Acts as an air tight barrier

Haven't had any problems since. 
Derek B.




I think it really depends a -lot- on the solder used, how it was
soldered, etc. NASA and anything for the military gets tested to
death in vibration and G-force testing. Anything automotive gets
similar testing at a much lower level. Poor solder joints that will
last years in a small circuit on your test bench may last a day in
a car or a pinball game.

How many G's a board can take is going to depend a lot on how it is
supported. Same with vibration. Anything that sticks up high from
the board is going to be more susceptable to damage.

I think an important part of this is going to be isolating the
shock of the charge from the boards. I've seen wiring get
overlooked- short straight segments of solid wire are going to
transfer shock a lot more than very slack sections of very flexible
stranded wire. Test lead wire is meant to take a lot of bending
without breaking.

Steve Greenfield

--- Dave King <KingDWS@...> wrote:
> Hi
> 
> This is a bit of a strange question. I keep stumbling into
> strange (but 
> interesting)
> projects to play with.
> 
> What is the maximum vibration level and/or G force standard smt
> or thruhole
> will tolerate ?
> 
> I've been asked if I could figure out a electronic detonator for
> an 
> airburst charge
> for snow guns. These are the guns/mortars they use to fire 4-8lb
> charges at
> potential slides to trigger them. The trigger will be a pic that
> simply counts
> and then fires a electric match after the preset delay.
> 
> I'm hoping this will prove tremendously difficult so I get to
> "work" and 
> have to blow
> things up all winter ;-]
> 
> Tia
> 
> Dave



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