I've got a device (a PocketWizard Plus X for you photographers out there) powered by 2x AA batteries that needs a shim of some kind behind the circuit board in order for it to work properly.

I used paper. Is that safe? Or will it start a fire? It's touching the backs of lots of the board components.

The shim is necessary because the device has a rotary switch that changes between 10 channels, and something in the switch has play, which in turn, causes the device to work only sporadically - as if it's stuck between the channels. The shim as installed solves the problem completely and it works as new.

If not paper - is there another material you might recommend?

This will be used exclusively indoors, and it's ideal if the batteries can be left in it.

  • \$\begingroup\$ How thick do you need it to be? Acetate could be a decent option and is easy to find (craft and baking stores). \$\endgroup\$
    – Wesley Lee
    Oct 21 '16 at 23:39
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    \$\begingroup\$ paper products are the traditional insulators of choice for centuries, perhaps plastic coated in recent decades. Cellulose insulation is still used (Kraft Paper) in high voltage transformers. \$\endgroup\$ Oct 22 '16 at 0:12
  • \$\begingroup\$ Although you are using it indoors, be aware that paper may absorb moisture if there is high humidity and that might not be desirable. \$\endgroup\$ Oct 22 '16 at 4:29
  • \$\begingroup\$ Just a few layers of electrical insulation tape folded back on itself so it doesn't stick (unless you want it to stick) would do the job fine. Enough folds to get the thickness you want. \$\endgroup\$
    – user98663
    Oct 22 '16 at 10:45
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    \$\begingroup\$ Your setup is not clear. Too much hand waving. This "shim of some king" sounds like a kludge that addresses a symptom, not the real problem, which you seem to have no interest in understanding. This is not a electrical engineering problem. Closing. \$\endgroup\$ Oct 31 '16 at 11:49

Paper won't cause a fire*, however there's a (small) chance it could affect the operation of the device due to leakage.

Almost any kind of plastic would probably be better (be a bit suspicious if it's black color because occasionally it's designed to be conductive). Just eyeballing what's around me and subtracting what is techie-specific (so much stuff), I see plastic covers on notebooks that could be easily cut with scissors. A 'Mead' 5-star notebook cover is about 0.5mm thick (0.02") and looks about perfect. Some thin binders or report covers are also a possibility and should be available cheaply in a dollar store or office supply store.

If you have any ancient overhead projector foils, that would be another one.

Rubber bicycle rim tape is another possibility (the kind that goes inside the rim to protect the tube). Put the adhesive on the side away from the PCB.

* Note that paper will not directly cause a fire, but it will sustain a fire so you would not typically find untreated paper in a real product that demands UL94 V-0 or similar material ratings. Many plastics such as polyethylene are also quite flammable. Often fire retardant additives are used to make plastics acceptable, can they can cause other problems (some are carcinogenic). In any case, that's not of too much worry in a device powered by AA alkaline cells.


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