Re: gEDA-user: PCB quad flat-pack symbols

["harry eaton" <bumpelo@comcast.net>]

>    In particular, I need a 144 pin and an 80 pin quad flat-pack with
> 0.5mm lead pitch...LQFP144_20 and LQFP80_12 look like the right thing,
> but I don't want to go through a whole layout and have boards fabbed
> only to find out these are 0.8mm instead of 0.5mm pitch, for example.
>
>    Can anyone shed some light on this for me?

You certainly don't need to go to fab to figure out an element pin spacing.
Place the element on your layout, then select a large grid spacing
(definitely
larger than 2x the pin spacing). Turn on "crosshair snaps to pins and pads"
in the Settings menu. Then move the cursor over a pin (the crosshair should
snap to the pin center). Now type Ctrl-M to place a marker on the pad
centerline. Then move the cursor over to the next pad. The cursor position
will indicate the distance between pin centers. Ctrl-M is a toggle-on,
toggle-off
for the marker.

There are some elements in the libraries that have bad geometry; you should
ALWAYS check the geometry before fabbing a board. I sometimes like to
print a postscript 1:1 paper copy and actually lay the parts down on the
paper to
see that they fit properly.

Cheers,
harry