Jon Chandler wrote:
> I like FreeDFM to catch gross errors, like flipped layers (which is a
> concern based on the original post).

That sort of stuff you catch when doing the quick look at the gerber files.

> A shortcoming of Eagle's DRC is that it doesn't check the final
> output -
> the Gerber files.  The design can be perfect but errors introduced at
> the final step.  When I installed a new version of Eagle, the CAM
> processor default was for mirrored bottom layers.  With all the
> options,
> it's easy to overlook especially since previous versions hadn't
> defaulted that way.

How could you not notice the bottom layer was flipped!?

If Eagle uses that as a default, that's a bad default.  Board houses want
all layers as viewed thru the board from the top.  However, if you've used
Eagle before you would have had your CAM jobs set up the way you do things
and they changing the default shouldn't have mattered.  Something doesn't
add up.  I didn't notice the Eagle default had changed because I've long ag=
o
set up my CAM jobs and the defaults don't matter anymore.

If you're having problems with gross errors, then you need to fix your
process.  Always put a short description of each layer in text a small
distance outside the board.  Examples are "Top copper", and "Bottom
soldermask".  I arrange them vertically so that the top to bottom order als=
o
matches the top to bottom order each layer will be on the finished board.
When you check the gerber files before sending out the board order, check
that each layer description matches the layer.  A flipped bottom layer
should be obvious anyway, but with the "Bottom copper" description string
there will be no way to miss it.  It also may help the board house fix it
for you if you screw up anyway, but you shouldn't rely on that.


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