Mark Willis wrote:
>
> Have a shaking application, where the PIC chip will be mounted on a
> piece of machinery that's vibrating.  A lot.  And am talking to someone
> making a rocket telemetry unit in future using a PIC chip.
>
> I'd sort of LIKE to socket this PIC chip, past experience (sumo robots
> etc.) has been that IC's tend to do spurious resets from short Vcc
> dropouts, etc. as the socket connectors bounce away from the IC pins,
> when these robots collide.  I suggested soldering the MOT cpu in for
> this particular app., seems my advice was good =)
>
> Anyone here know what type of sockets are best for vibration-type
> environments?  In future I'll be doing TOO much shaking applications,
> some rocketry telemetry (I hope!) included.  I'd think an Augat would be
> pretty good (multi-prong machined pin socket.)  I've thought of using a
> ZIF socket, even though expensive they're pretty solidly contacted.  Or
> is solder just THE best here?  (With /JW parts, versus flash parts,
> things have changed to where soldering is not as bad of a pain as it
> once was, with ICSP being available!)  Nice to avoid soldering if I can,
> though.
>
> One cheat for when you know there'll be socket drop-outs or power
> faults:  Hard solder a cap or two across the uController, and perhaps do
> the same for your pull-up resistor for !MClr - that tends to reduce
> problems.  (But: it's a pain!)
>
>   Mark

Mark, I had some experience with electronics in Racing Car environment.
Just to you have an idea about vibration, some drivers need to replace
their dental fillings quite often (specially when they hit the wall...
hehe).

There are two ways to protect electronics: a) create a cushion system
for each sensible component, or b) tied as firmly as possible that
component to the pcb.  It sounds crazy, but sometimes cushion means
broken leads, some components just got ripped of from the board. It is
not difficult to find out some DIP 14 chips with two or more broken
legs, not even talking about circuit board thin tracks just cracked or
floating in the air. Missing smt resistors and capacitors is not rare.

The best thing to do is find out the vibration frequency and look for
the best cushion system for that particular frequency.  A complete
different cushion is required for a V-8 or V-12 cylinders engine racing
car.

A tick resin covering all components (epoxy or araldite) is what you can
find in some surplus boards, clearly sold somehow from military crafts.
Forget about maintenance.

Circuit board and tracks should be as tick as possible, sometimes with a
metallic frame to keep it straight.

If you really need sockets, the machined golden ones with an extra chip
holding clip would be a must. I would go for Flash devices that can be
on board programmable, avoiding sockets at any cost.

Use several small power capacitors around the board instead single big
one.

Silicon glue all crystals parallel to the board, with "S" leads shape to
avoid problems.

Just to have an idea what it is, just drop 10 ice cubes into the blender
and turn it on at max speed, imagine your circuit right there, close to
the blades, and think about which part will break first.

It is a complete new world.