Question about Placing Vias on Four Layer Board with TWO Internal Ground Planes

[Joepuck]

My design is a four layer board.  Top and bottom surface layers are for routing traces and power.   Two inner ground planes (one above the other separated by an insulating layer) are for making all ground connections.  Customer specifies that all ground connections need to be made to BOTH inner ground planes.  When I attempt to place a via that will connect an outer surface trace to ground, I am not allowed to connect to more than one inner plane.

I need to place vias that completely pass thru the board and connect an outer surface trace to BOTH inner ground planes.. Is there a way or setting that will allow me to do this?

Running Ultiboard V10.0.144.

Thanks

[Tayyab_R]

Hi Joepuck,

It should not really be an issue to place a via that goes all the way through the board. When you place a via, a window pops up asking you the lamination. You can select from Copper top to Copper bottom. This will place a via which goes through the entire board. If you already have a via placed, double-click it and go to the Layer Settings tab and make sure all the layers are checked.

Hope this helps.

[Joepuck]

Hi Tayyab - I am running Ultiboard Version 10.0.144.  Yes, I can place a via that goes all the way through the board.  Yes, it places a pad on each layer.  My two inner layers are solid copper.  The pads of my vias need to connect to BOTH of these solid copper layers.  The problem I have is there is a space between the via pad and the copper plane.  How do I get rid of this space and connect to both planes?

Thanks..

[Joepuck]

Tayyab - Here is the sequence I follow, maybe this will help you to help me:

Copper Top is the current layer, Copper Inner 1 and Copper Inner 2 are on, visible as phantoms.

Place Via, From Layer Copper Top To Layer Copper Bottom, OK.

A via appears.  A pad is visible on each of the four layers.  There is a cleared out area in the copper around the pads of the Copper Inner 1 and Copper Inner 2 layers.

The only way I can get a via pad to connect to an inner layer:

Right-click on pad, choose properties, via tab, click Assume Net.

Pick the net "DGND" from my pulldown list.

Click Thermal Relief tab, choose No Thermal Relief, apply, OK.

This connects the via pad to the copper plane of Copper Inner Layer 1.  That's good, but I need to connect the via pad of copper inner layer 2 to the copper plane of Copper Inner Layer 2 too.

Help!!

Thanks..

[Tayyab_R]

Hi Joepuck,

That should work. Is it possible for you to create a Service Request and send us your file. We can try to find out why it is not connecting. If both power planes are DGND, they should both connect in the same manner.

[Joepuck]

How do I make both inner power planes "DGND"?  I can't remember how I made Inner Power Plane 1 "DGND" - can you remind me how to do this?  I do not have a service contract with NI, so I cannot create a Service Request.

Thanks..

[Tayyab_R]

What you can do is un-check Copper Inner1 from the design toolbox to disable that layer. Then you can double-click on the power plane on Copper Inner 2. Go to the Copper Area tab. Here it will indicate which Net it is connected to. Make sure it is connected to net GND.

[Joepuck · Accepted solution]

Solved my problem.  Made Inner Layer 2 the current layer, turned off all other layers.  Pointed to Inner Layer 2, r/c on Properties, Copper Area tab, click Connected to Net, choose DGND from pull-down list, apply, OK. Now, place a via. R/c on it, choose properties, via tab, click assume net, choose DGND from pulldown list, apply, OK.  the via now connects to both Inner layer 1 and Inner Layer 2, b/c both are now associated with the net DGND.

Beautiful - Thanks..