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Re: gEDA-user: prohibited areas on data sheet?

On Thu, 06 Jan 2011 01:51:27 +0100
Kai-Martin Knaak <kmk@xxxxxxxxxxxx> wrote:

> Frank wrote:
> > I'm creating a footprint according to the datasheet, and it has 3
> > different prohibited areas on the footprint. I'm not sure of the
> > exact meaning of these areas. Can someone explain?

Generally this means that the "prohibited" areas must be left clear of additional parts, copper, vias, or some combination of the three, even if they might otherwise easily fit under and around the component in question, usually because some feature of the component might physically interfere with or short out against whatever is placed in those forbidden areas.

The way I read this particular datasheet:

*  The black "Prohibited" area on the right of the footprint should be left clear of all components because such things would mechanically interfere with a switch located in that area.  I don't see anything that would make copper in this area a problem, though.

* The crosshatched "Solder Prohibition" area needs to be kept clear of solder-coated copper, because the extra thickness of the solder creates a risk of shorts against the SD card contacts.  I'd avoid vias as well, for the same reason, and bare copper for the save of safety.  Limited passage of soldermasked polys/traces through this area should be okay.

* The shaded "Pattern Prohibition" area needs to be kept clear of all copper.  My guess is that either those SD card contacts rest against the circuit board when the slot is empty, or the body of the slot flexes outward when a card is inserted.  In both cases, those moving bits of metal make even soldermasked copper a short circuit risk in this area, given enough time.

"There are some things in life worth obsessing over.  Most
things aren't, and when you learn that, life improves."
Vanessa Ezekowitz <vanessaezekowitz@xxxxxxxxx>

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