>I have seen DIP chips with their legs bent UP instead of DOWN and then
>mounted as usual and therefore "upside down". Makes for a very strange
>pinout and with power supply on pins 1 and N/2+1 for standard logic parts.
>Slows down the honest folk.

>Obviously something I wouldn't recommend :-) .Mounting ICs bent as above on
>the bottom of the PCB still through-hole yields standard pinouts. This
>method can also be used to resolve the disaster that occurs when somebody
>gets the copper side wrong in a PCB run and a mirror image PCB results -
>I've seen it done in a commercial product ! :-)



This bending of chip legs needs to be done with much care. I worked with a
guy who got involved in doing this on a research project because of a
mistake in laying out the PCB, and they found the chip concerned would fail
every few weeks. They then went through some loops to install an IC socket
so that they no longer needed to bend the chip legs, and the failures
stopped. It seemed that bending the leads so the chip could be inserted
upside down damaged the hermetic seal at the plastic/lead frame point and
let moisture into the chip resulting in short term failure.

Incidentally Russell, this happened at Auckland University.

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