Why place power polygons on signal layer?
miner_tom , 07-18-2021, 10:06 PM
Hi Robert, In the 6th video of your Advanced layout course, at about 1:23, you mentioned that in your designs you like to keep the power plane open while using a signal layer for polygonal power pours. When you do that doesn't it mean that you have to route around the power pours? This may have the effect of increasing signal lengths. I am not sure that I properly understood what you were talking about.
Regards
Tom
robertferanec , 07-19-2021, 05:06 AM
Altium stackup manager uses the term "signal" layer for a layer where you "draw" copper (positive layer). Altium uses the term "plane" for a layer where you "remove" copper (negative layer - it means, everywhere is copper by default and everything you draw will be the places where copper will be removed).
So, I do not really draw the polygons on layer with signals, but rather on "signal" layer (means on a layer which Altium sees as a layer where we "draw" the copper)
I know, it is confusing, but that is how they call the layer types.
Comments:
miner_tom, 07-19-2021, 10:40 AM
Robert, I am greatly relieved for your answer. So, for example, in the stackup, I can have a layer with a name, which does not correspond to any particular net. This is considered a signal layer, where I would be free to add polygons (copper pour) that do correspond to nets. Correct?Then, if I had another layer, that did have a name corresponding to a net, say GND, then that layer would be composed of copper corresponding to GND. Correct? So, this would be a plane layer and I would not have to do a pour to know that copper is there. Anything that I could draw on the plane layer would remove copper from that area, according to the rules that were set. Is that also correct?Thank YouTom
robertferanec , 07-20-2021, 05:19 AM
The name of layers can be anything - it is just text it has nothing to do with electrical connections on your PCB. You assign a net to "plane" when you double click there. This may help:
https://youtu.be/fhiamy6MA8k?t=243Everything else you explained is correct.
Comments:
miner_tom, 07-20-2021, 09:52 AM
Robert, yes, it did help. Thank YouTom
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