Leo,
Yes I have seen this issue as well, wrecked a board or two over the
years. It is some bug that seems to be particular to specific detailed
geometries in a poured polygon area. I am assuming that you have a polygon
where this shows up, it has always been such on my designs. It may effect
planes under certain circumstances but I have never seen it there because I
barely ever use true planes.
The only fix that I have found is to tweak the polygon outline slightly
in the area effected. Move the polygon vertices by some small amount and then
repour. It seems to usually occur near a vertice for the polygon outline or
where you have a vertice for a cutout or clearance area (watch for small tight
acute angles on the polygon pour outline, cutout or just how the polygon has
poured with the clearance rule). So moving the polygon or a cutout vertice just
slightly (+/-5mils - +/- 50mils) seems to fix it. You may have to try a couple
of different vertice moves until the Gerber comes out correct. Another option
is to vary the clearance (even as little as +/-1 mil) for that polygon as well
so that the actual poured polygon edges have been moved slightly.
Sincerely,
Brad Velander
Senior PCB Designer
Northern Airborne Technology
#14 - 1925 Kirschner Road,
Kelowna, BC, V1Y 4N7.
tel (250) 763-2329 ext. 225
fax (250) 762-3374
-----Original Message-----
From: Leo Potjewijd [mailto:[EMAIL PROTECTED]
Sent: Monday, September 19, 2005 5:31 AM
To: [email protected]
Subject: [PEDA] arcs in Gerber go the wrong way
On the PCB (P99SE) all my arcs look great, even on the print preview.
But in the Gerber files some, not all, are wrong: the start and end in the
right places, but go the wrong way around. So a 90 degree turn ends up as a
270 degree turn with another center and shorts stuff......
It happened once before, but the fab house detected and reported that error
so they could correct it in time.
Like now, I could not identify the source of the problem and have no clue
whatsoever....
I checked the PCB at ASCII level but could not find any indications what
went wrong (a 'good' one looks exactly the same as a 'wrong' one). I even
generated the Gerbers from that copy: no luck.
Inside the Gerbers I am at a loss: I cannot identify arcs, let alone the
right and wrong ones.
Has anyone seen this before and found a solution or workaround?
Checking the 'software arcs' box is not an option: that messes up the
already tight clearances (had a close shave with that one, too).....
Leo Potjewijd
hardware designer
Integrated Engineering B.V.
[EMAIL PROTECTED]
+31 20 4620700
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