possible to have two power polys on the same layer?

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evanrich
Posts: 42
Joined: Thu Jan 27, 2011 8:46 pm

possible to have two power polys on the same layer?

Post by evanrich » Thu Jan 26, 2012 4:40 pm

In eagle, specifically 6.1, is there a way to have two power polys (+5 and GND) on the same layer, but of course isolated? I've got 5V and GND traces all over the place, and I'd like to be able to lay down planes for 5V where possible to increase current capabilities. I have a problem though, because when I first do "poly GND", and draw the ground plane, then do the +5V, the 5v lays directly on the GND plane, thus "shorting" them out. I also tried switching the GND to Rank 2, and then doing the +5v on rank 1, this caused the 5V to take precedence and not show the ground in areas ground should fill.

I've also tried using the "isolate" feature on both planes, but this did not change the shorting. The only way I could see doing it is to lay down the ground plane on Rank 2, then hand draw polygons for +5v in 5v areas, instead of doing one large poly across the board and having it auto fill where 5v was, but not overlap the GND.

Any ideas?

langwadt
Posts: 64
Joined: Fri Aug 26, 2011 1:50 pm

Re: possible to have two power polys on the same layer?

Post by langwadt » Sun Jan 29, 2012 6:38 am

you have to hand draw one of the polygons and let eagle fill out the rest like you suggest.
think about it, how could eagle possibly guess where you want what polygon if you just put them on top of each other?

evanrich
Posts: 42
Joined: Thu Jan 27, 2011 8:46 pm

Re: possible to have two power polys on the same layer?

Post by evanrich » Mon Jan 30, 2012 12:11 pm

I guess you're right, I just figured that it would fill the best of both out, but what you said makes sense. I tried it on a small area and it worked as intended, so I'll just have to hand draw the entire 5v plane out.

Edit:

I guess what I am looking for is if there is a way to have a wire expand out to fill the area around it. Much like how a ground/power poly will fill in any open space, I'm trying to do the same for the 5v lines as well. The problem is, that since I'm using a 2 layer board, i can't just have one of the middle layers be power, I've got power traces among signal lines. While the trace width is wide enough to accommodate the current I'll be using, for a better margin I was going to try and have the 5v lines get wider where space between traces was available.

Thanks.

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