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I have a four layer board: Signal, GND (internal power plane), VCC (internal ground plane), signal. My design includes a chip antenna that requires a completely cleared region at the edge of the PCB. In other words, all four layers in this region must be clear of copper of any kind. I know how to do this on the signal layers by simply limiting the size of my polygon pours on these layers. What I don't know how to do is maintain this cleared ares in the internal power and ground planes. I've played with keepout and cutout regions without success. What's the best approach?

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Simply place a filled rectangle or polygon on the power and ground planes. Anything you place on the plane layers will become "not copper" on the finished board.

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  • \$\begingroup\$ For clearing all layers, you can also just put a feature on the Keep-Out layer. \$\endgroup\$ – The Photon Apr 15 '14 at 23:21
  • \$\begingroup\$ The proper thing to remember here are internal planes are negative layers. In other words, they are bu default copper-filled, and anything you draw in them becomes a empty region. \$\endgroup\$ – Connor Wolf May 16 '14 at 4:28
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The Keepout layer will only prevent copper on your routed layers. Depending on how you generate your pcb, you can get the same effect on your power/ground planes by using the board cutout feature. For example, define your board shape with the Mechanical 1 layer, and then place a board cutout where you're going to place your antenna. As long as you don't use the routing path feature, you'll be fine.

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I've recently successfully used cutout regions for exactly the same purpose. I'd never used them before so it took a little tinkering, but it does work.

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