>pin to pin capacitance

about 10 pF row to row in 5 pin long parallel rows. This is enough to
upset any CMOS circuit that uses AC of any sort. Been there. Anyway most
correctly designed PIC applications are not impressed by this if no input
pins are ever left unconnected.

The aluminium backing should be grounded at all times. I found that
otherwise new and unexpected coupling paths can happen.

Peter

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