Weird Pad Behavior - Traces Not Connecting Properly
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bryan costanich 1 year ago
Hey folks, I'm laying out a PCB using this 13.56 MHz NFC antenna footprint: [https://easyeda.com/components/13-56MHz-NFC-Antenna_a91e4959524c4400bf527e26e3e5bf4b](https://easyeda.com/components/13-56MHz-NFC-Antenna_a91e4959524c4400bf527e26e3e5bf4b) and i'm getting a weird connectivity bug in when i try to lay a trace to it's pads. With one, the trace doesn't get clipped over the pad, and with the other, the trace won't connect: ![Screen Shot 2020-12-20 at 11.01.56 AM.png](//image.easyeda.com/pullimage/meMH6thxH4GnFj3XSbYI0uvbOR5gDQKAZEa42G4q.png) but in the part, the pads all look normal: ![Screen Shot 2020-12-20 at 11.02.17 AM.png](//image.easyeda.com/pullimage/4ANU9bsYtfAxPL7eHPcs6cTYJ3ZXIB2zEM5VSy46.png) any ideas?
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andyfierman 1 year ago
There are two problems here. 1) You will always get a DRC error with a PCB track antenna like this one because it is just a short circuit between two nets. Unless the two nets being connected to it have the same net name, that will generate a DRC error. There have been several topics about this issue and as yet the only way to avoid the DRC errors is to connect to one end of the antenna track via a 0 Ohm link or a matching network that includes at least a series component to break the net so the names each side of the series component can be different. 2) I suspect you have Realtime DRC enabled in your System settings and have a routing attribute set to Block in the PCB Canvas settings so that routing will be blocked for any realtime DRC error.
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bryan costanich 1 year ago
So how do I make a 0Ω link? Are you talking about a zero ohm resistor, jumper or similar? or is there a way to make some sort of wire/trace copper pour link? i searched and found your previous post on it, but i'm still confused. I found your [sample project about how to create an antenna like this](https://easyeda.com/andyfierman/how-to-make-a-connectable-antenna), but when I opened it up to try and route some traces between the pads, i got the weird jumping snap err that you did, so I opened your _SINGLE\_NUMBERED\_MULTI\_PAD_ part I didn't see any links or anything.
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andyfierman 1 year ago
I mean a physical 0R resistor. And yes, you have found the problems I was referring to in (1) in my first reply.
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andyfierman 1 year ago
Or a capacitor as part of a matching network. No, a copper "link" will not work for exactly the same reasons a PCB antenna throws DRC errors.
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bryan costanich 1 year ago
Balls. Not great solutions.
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andyfierman 1 year ago
Agreed. I  have raised this as an issue some time ago. Hopefully the new PCB Editor will address it, when it is released but like a few other things this last year, the plan got a bit bent out of shape. :)
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andyfierman 1 year ago
@bryan_6020, As long as you understand the causes and their effects, you can work round these issues. You can ignore the DRC errors that connecting to a shorting track will create or you can rename the nets to allow for the short circuit forcing all the tracks connected to the antenna to have to be the same. Neither is very elegant but at the same time neither stops you producing a perfectly good PCB.
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Markus_ee 1 year ago
Hi! Changing a routing conflicts from "block" to "ignore" means that you can connect to any pad in the layout but I do urge caution with this option: ![image.png](//image.easyeda.com/pullimage/j6BdtGyTIzgSEdzM1cdo8S0DH7feyndoPQE6bs3P.png) I suggest using this only when routing only this trace and the you can set it back to block in order that you don't make mistakes in other traces by mixing traces to wrong pads. Regards, Markus Virtanen HW / Electronics Designer
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