Streaky/split polygon ground plane

On 2008-05-08 07:45:39 +0200, Martin van den Nieuwelaar

<martin@rawl.co.nz> said:

I have designed a double-sided board with ground planes on both sides

of the board.  When I print (as in File->print) the board with output

to a Postscript file, then view it (using evince - I'm running Ubuntu

by the way), I see both the top and bottom ground planes have small

horizontal slits in them.  A photo is worth 1000 words as they say.

The photo came through OK.

You have a lot of layers turned on. If you display only the top layer,

do you still see the slits?

I suspect this is a graphics problem of your OS, not Eagle.

Notice that the edge of the polygon is never affected, just the

inside.  Other signals (the regular looking traces in the image)

appear just fine as well.  The width of the polygon affects the

spacing of the streaking.  It's like there isn't any overlap of the

lines used to create the solid fill, and sometimes we see 'through'

between the lines.

You could try to change -> pour -> hatched and then back to fill, does 

that help?

--

Eur van Andel  eur@fiwihex.nl

On Thu, 8 May 2008 Eur van Andel wrote saying :

 

The photo came through OK.

 

Yes, and it shows the problem Martin was reporting quite nicely

You have a lot of layers turned on. If you display only the top layer,

do you still see the slits?

 

I don't think that has anything to do with it.

I suspect this is a graphics problem of your OS, not Eagle.

 

No, it's not. I have the same issue when printing to a

pseudo-post-script printer using Eagle 4.15 and with only one layer

visible. It's a quirk of the way flood areas are encoded into

post-script, I suspect, probably exacerbated by tiny variations in

interpretation between CadSoft's test environment and ghostscript (since

Martin is on Linux and my printer is hanging off a Linux server to get

post-script capability).

Changing to hatched and back makes no difference, but I think I found

that setting the width/isolate/spacing differently helps.

--

Rob Pearce                       http://www.bdt-home.demon.co.uk

The contents of this | Windows NT crashed.

message are purely   | I am the Blue Screen of Death.

my opinion. Don't    | No one hears your screams.

believe a word.      |

Robert Pearce wrote:

On Thu, 8 May 2008 Eur van Andel wrote saying :

You have a lot of layers turned on. If you display only the top layer,

do you still see the slits?

 

I don't think that has anything to do with it.

Just out of curiosity, I tried printing just the top layer, and it

exhibits the same problem.

I suspect this is a graphics problem of your OS, not Eagle.

 

No, it's not. I have the same issue when printing to a

pseudo-post-script printer using Eagle 4.15 and with only one layer

visible. It's a quirk of the way flood areas are encoded into

post-script, I suspect, probably exacerbated by tiny variations in

interpretation between CadSoft's test environment and ghostscript (since

Martin is on Linux and my printer is hanging off a Linux server to get

post-script capability).

So what OS are you running Robert?  I thought about trying all this

under Windows, but setting it all up was going to be some work (mainly

due to security restrictions at my work).

Changing to hatched and back makes no difference, but I think I found

that setting the width/isolate/spacing differently helps.

Indeed, changing to hatched and back doesn't help for me either, but I

have also fiddled with the width/isolate/spacing settings without

managing to remove the problem.  My understanding is that 'spacing'

only affects hatched pour regions; trying different values here when

using a solid pour didn't seem to change anything.  'Isolate' didn't

help me either; it just results in more/less space between the pour

and other tracks (as I believe it's intended).  'Width' does help a

little, but I believe simply by the fact that by making it large,

fewer lines are drawn to make up the solid pour thereby reducing the

number of edges and hence spots for the background to 'leak through'.

  I didn't manage to find a setting that was acceptable.

Fortunately this time I'm not using the print output for generating

PCBs, but the CAM output instead.  In the past however, when making

quick mock-up PCBs at home I did use the print output option (hack

saw, UV box, bubble tank, drill press...), so it would be nice to

solve this little puzzle.  I think when I used to make PCBs at home,

they were always small and I didn't really know about ground planes

and polygons back then, so never used them.

Regards,

-Martin

On Mon, 12 May 2008 Martin van den Nieuwelaar wrote saying :

So what OS are you running Robert?  I thought about trying all this

under Windows, but setting it all up was going to be some work (mainly

due to security restrictions at my work).

 

Nearly all my Eagle work is done on Gentoo Linux, but I've played with a

Windows version in the past. I don't actually remember whether the

problem happened with that.

Indeed, changing to hatched and back doesn't help for me either, but I

have also fiddled with the width/isolate/spacing settings without

managing to remove the problem.

That's a shame.

Now I come to think of it, I had one design that showed the problem if

printed directly on Linux, but not if I printed to a file and took that

to somebody else's printer. I don't recall for certain whether that was

a Windows box or a Mac (there was even a NetBSD server in the room, but

I don't think I used that).

--

Rob Pearce                       http://www.bdt-home.demon.co.uk

The contents of this | Windows NT crashed.

message are purely   | I am the Blue Screen of Death.

my opinion. Don't    | No one hears your screams.

believe a word.      |