I am migrating a design from Eagle to Altium and on the Eagle PCB there is a ground plane (polygon) and every pad has its own GND via.

So I placed the ground polygon as on Eagle, and Altium registers all ground connections as made. So I was wondering, do I still need to place GND vias on every pad just as on Eagle?

Is it so that placing the polygon and GND vias help reducing current gain in components?

enter image description here

  • \$\begingroup\$ What options do you have? What components having current gain require that current gain to be reduced by ground plane polygon and how do you determine that this will happen? Without knowledge of the circuit who can answer or understand this question? \$\endgroup\$ – Andy aka May 9 '16 at 11:33
  • \$\begingroup\$ Can you show us your design? What pads have ground vias next to them? \$\endgroup\$ – DerStrom8 May 9 '16 at 12:05
  • \$\begingroup\$ I edited my original question. I don't know if this is enough information. Do I need t place a GND via on this polygon or is the connection made as is? \$\endgroup\$ – Jordakoes May 9 '16 at 12:13
  • \$\begingroup\$ It's still not entirely clear, but if I'm understanding you correctly the red "GND" pads are showing as connected to the blue "GND" poly. Is this right? If so, the connection may be made elsewhere so Altium will register it as done, but best practice is to use a ground via next to each pad to shorten the return path. This prevents noise and poor operation. \$\endgroup\$ – DerStrom8 May 9 '16 at 12:30
  • \$\begingroup\$ That is correct, I am an intern working for this small company designing PCBs for the automotive industry. And having fewer noise on the print is very very important. \$\endgroup\$ – Jordakoes May 9 '16 at 12:42

The answer to your question is "No, you do not need to have a via for every pad if they're already connected to the GND pour".

However having generous amounts of stitching GND vias between layers is a Good Thing. Consider looking at your PCB one layer at a time where it's easier to see if you've got semi-isolated GND islands. Rule check is happy with a single via connecting various GND planes together but your circuitry won't be.

The screenshot makes me think the blue area is on bottom side and red on top. Switch to a single layer view to see how the top side is connected.

  • \$\begingroup\$ Thanks I will be placing additional GND vias next to having the GND polygon. The blue area indeed is the bottom area, and the red is the top area. \$\endgroup\$ – Jordakoes May 9 '16 at 13:29

Generally the more vias you have, the less you ground plane (or other polygon) is effective. The basic intension of having a polygon or a plane is to reduce impedance to minimum and have same potential at all points. So too many vias is not good. Yet, if there are several planes with same net (like two grounds, on top and somewhere in the middle), you want them to be at same potential too. So normally "natural" viaz are enough. I mean those that are there for ofhe purpose, like connecting capacitors to plane. Frankly, i have never saw other case. But if you feel there may be current that will flow on one plane and will not in the other, add several vias to equalize potential.

  • \$\begingroup\$ Ok but another problem that occurs placing vias is that when I ''repour'' the Polygon. The gnd vias get repoured aswell causing them to short circuit or unconnect to the gnd plane. \$\endgroup\$ – Jordakoes May 9 '16 at 13:53
  • \$\begingroup\$ You're right about polygons generally needing to be low-impedance, but also remember that you need a solid ground connection and clean return path. \$\endgroup\$ – DerStrom8 May 9 '16 at 13:54
  • \$\begingroup\$ @Jordakoes make sure you have the via nets set to "GND". Also check the polygon connect rules -- For vias you want a "Direct connect" \$\endgroup\$ – DerStrom8 May 9 '16 at 13:55
  • \$\begingroup\$ @jordakoes, i am not closely familiar with altium, so i don't want to answer about specific technics. \$\endgroup\$ – Gregory Kornblum May 9 '16 at 13:57
  • \$\begingroup\$ Derstrom8, what is your definition of solid ground? It's exactly the low impedance, same potential plane. \$\endgroup\$ – Gregory Kornblum May 9 '16 at 13:58

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