Connection of two internal grounds at a single point with Net-Tie
KOVA , 03-09-2020, 03:29 AM
Hello to everyone.
This is my first post on the Forum.
Cureently I am working on an embedded application for my Master Thesis and I would like to have your proposal on an important detail with ALTIUM (17.1).
It is a 6 Layer Board with two separate ground planes, one for power modules and one for signals, which need to be connected at a single point.
I used the “Net Tie component” from the section “Intentionally Connecting Two Nets”, found on
https://www.altium.com/documentation/altium-designer/creating-connectivity-ad?version=17.1#!intentionally-connecting-two-nets
Some usefull information also found:
https://smtnet.com/library/files/upload/NetTies-and-How-to-Use-Them.pdf
What I did was to create a new component, marking it as a Net-Tie. I took two pads and placed one exactly above the other, same size and same drill. I took this part on my PCB (after the proper connection on schematic) and it aligned with a power capacitor’s pin, connected to the ground. It seems that no connection takes place. I checked also the gerber files with View Mate and the look exactly the same.
- So my question now is, which is the best way to connect two internal planes at a single point? Isn’t it beneficial to just use a drill that already exists on the board, by means of a component like electrolytic capacitor close to the main input? I haven’t seen it anywhere else though.
With engineering greetings from Greece,
KOVA
This is my first post on the Forum.
Cureently I am working on an embedded application for my Master Thesis and I would like to have your proposal on an important detail with ALTIUM (17.1).
It is a 6 Layer Board with two separate ground planes, one for power modules and one for signals, which need to be connected at a single point.
I used the “Net Tie component” from the section “Intentionally Connecting Two Nets”, found on
https://www.altium.com/documentation/altium-designer/creating-connectivity-ad?version=17.1#!intentionally-connecting-two-nets
Some usefull information also found:
https://smtnet.com/library/files/upload/NetTies-and-How-to-Use-Them.pdf
What I did was to create a new component, marking it as a Net-Tie. I took two pads and placed one exactly above the other, same size and same drill. I took this part on my PCB (after the proper connection on schematic) and it aligned with a power capacitor’s pin, connected to the ground. It seems that no connection takes place. I checked also the gerber files with View Mate and the look exactly the same.
- So my question now is, which is the best way to connect two internal planes at a single point? Isn’t it beneficial to just use a drill that already exists on the board, by means of a component like electrolytic capacitor close to the main input? I haven’t seen it anywhere else though.
With engineering greetings from Greece,
KOVA
robertferanec , 03-11-2020, 01:53 AM
I have not used net tie yet, but I always imagine the footprint of net tie as a resistor footprint (a footprint with two pads), just the two pads are shorted together. I am not really sure how it would work if the pads are through hole and placed on top of each other - interesting idea.
I believe, the problem is, that if you place the pads on top of each other, you have two rules in conflict - one rule is saying to connect it and the other is saying to not connect it. And it looks like the rule to not connect it has higher priority. Maybe if you play with PAD size on specific layers, it could work (e.g. on layer where the GND1 should be connected, leave standard ring on the VIA connected to GND1, but make the ring 0mm on the pad what is connected to GND2). I am not sure if that helps, but maybe it could work (but it is not a system solution).
I believe, the problem is, that if you place the pads on top of each other, you have two rules in conflict - one rule is saying to connect it and the other is saying to not connect it. And it looks like the rule to not connect it has higher priority. Maybe if you play with PAD size on specific layers, it could work (e.g. on layer where the GND1 should be connected, leave standard ring on the VIA connected to GND1, but make the ring 0mm on the pad what is connected to GND2). I am not sure if that helps, but maybe it could work (but it is not a system solution).
KOVA , 03-11-2020, 07:13 AM
Many thanks for your reply Robert.
I am also not fond of the Net-Tie as a resistor-type component and that's why I'm searching for another way
Could you suggest me another way (more close to a"system-solution" as you said) to connect two GND-Planes at a single point?
I am also not fond of the Net-Tie as a resistor-type component and that's why I'm searching for another way
Could you suggest me another way (more close to a"system-solution" as you said) to connect two GND-Planes at a single point?
robertferanec , 03-11-2020, 12:52 PM
I often use 0R resistor for that.
xddarko , 05-09-2020, 07:52 PM
You can create a footprint yourself .
I do not use any resistor. Just a footprint with two rectangular pads connected with a wire or a copper fill.
I do not use any resistor. Just a footprint with two rectangular pads connected with a wire or a copper fill.
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