A basic component on many boards is a CPU chip, or 555 timer. 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. solarwind wrote: > On Wed, Aug 12, 2009 at 7:56 PM, Derward Myrick wrote: > >> Solarwind, It is necessary to reverse the pattern on many parts. >> > > Could you please provide an example? I don't understand why you would > need to reverse the design if all you are making is a single sided PCB > with only through-hole components on one side (the FR4 side, not the > copper side). > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist