On Wed, Aug 12, 2009 at 9:33 PM, Carl Denk<cdenk@windstream.net> wrote:
> A basic component on many boards is a CPU chip, or 555 =A0timer. Both pin
> layouts are asymmetric about both orthogonal (right angle) axis. If you
> can't solder components (including sockets) to the same side as the
> copper traces if the socket plastic gets in the way, the component must
> be located on the other side. Then if the layout was for the component
> on the copper side, the traces won't go to the correct pins.
>
> If the layout is only symmetric parts, or they can be mounted either
> side (resistor thru the hole leads) then the only issue is the actual
> placement of the parts, it is easy to get a part backwards, say if it
> has 3 pins like a 7805 regulator, center pin is ground which is OK, but
> the outer pins are in and out, don't get it backwards.

Right, but that only matters if you are top soldering and bottom
soldering. If you do it right (solder on the FR4 side only) with only
through-hole components, then no reversal is necessary.

-- =

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