Re: gEDA-user: A couple o' questions

[Karel Kulhavy <clock@xxxxxxxxxxxxx>]

On Wed, Apr 05, 2006 at 10:26:57PM -0400, Stuart Brorson wrote:
> > PCB does min annular ring checks as of several weeks ago.
> 
> Great!  THis is an important check!  Thank you!
> 
> [ . . . .]
> 
> > By soldermask bridge width do you mean minimum width in between 
> > soldermask relief areas?
> 
> Yes.  In particular, I am interested to check that the soldermask
> separating two pins (or a pin and a via, or two vias) is sufficiently
> wide.  Otherwise the possibility of an inadvertent solder bridge
> exists.  
> 
> > Can you elaborate on "metal slivers"?
> 
> I mean thin little slivers of copper formed when a circular antipad
> and some other structure get close to one another, creating a little
> wedge of copper which sticks into nowhere.  These apparently can cause
> strange etch effects, and are bad for DFM.
> 
> In the same catagory are slivers of space between metal, where the
> etchant can apparently concentrate, and eat away more copper than is
> desirable.  
> 
> Please don't ask me to speak more knowledgably about these strange
> etch effects -- I am not a PCB fabrication expert.  I only repeat here
> what I have been told.

When I sent Ronja Twister for manufacture they told me I have slivers
there and that I must take them out because they can otherwise peel off,
float and land somewhere else, shorting tracks.

Since that time I remove the slivers automatically. I print out the
copper plane, do a visual inspection, circle the slivers. Then I go to
the place, delete the rectangle and replace it with more rectangles that
do the same as the original polygon but without the sliver.

Since then the manufactured never returned the board files because of
slivers.

CL<
> 
> Stuart