Learning Forum

[Yoon Jung]

I have a question about creating a via hole

I know that when I create a via hole, I need to create a cylinder and subtract it from the substrate.  I'm designing a GCPW and I'm wondering if I should make the start of the cylinder overlap the commonGND, or if I should make it exactly like the start of the substrate and make it as tall as the substrate. In other words, should the height of the via be substrate + ground*2 (top and bottom) or should it be exactly the height of the substrate?

And if I create a via hole and then specify a finite conductivity (set the material to cooper) and set the thickness, is this via a via hole that is air inside and copper by thickness?

 

And when I create the via hole, what if I want to fill it with another material (ex. Polymer)?

[GioF]

 

Hi Yoon,

If you create a cylinder and subtract it from the substrate without using the clone option, a vaccum hole will be created (via “filled” with air if the outer box has been assigned to a vaccum material). On the face of the vaccum hole you can define your Finite Conductivity boundary condition and connect the upper with the lower ground. The cylinder should have the height of the substrate.

If you want to fill it with another material you have to create your cylinder, assign it to you Polymer material and then enable the “Clone tool objects before operation” option. After adding the Finite Conductivity Boundary in the face of your cylinder, you will have a via connecting the upper and lower ground filled with Polymer.

 

[Yoon Jung]

Thanks for the answer!

When I connect the via hole with the upper and lower ground, do I just select the three and unite them? And when connecting, do I have to select each face and not the object of the cylinder?

Also, in your answer (via "filled" with air if the outer box has been assigned to a vaccum material), what exactly does outer box mean? Do you mean something like a radiation box? If I have a cylinder (via hole) in the substrate and it is covered with a thin copper on top and bottom, does subtracting it automatically fill it with air?

When I assign Finite Conductivity, should I add it on all 3 faces, 2 circular faces and 1 curved face? (because I read on the internet to add it on the curved face only)

[GioF]

It is not necessary to unite them. 

Yes when I talk about outer box, I am refering to the box where the Radiation Boundary is assigned and where your cpw will be placed inside. The subtraction will leave some "empty space". This empty space will be filled with air if the outer boxes material is vacuum. 

You should add it only in the curved face. The top and bottom circles should touch your copper conductors so there is no need to set Finite Conductivity there.

[Yoon Jung]

If I want to fill the via with a different material

Create Cylinder -> assign Polymer -> Subtract Cylinder from Substrate (enable Clone tool objects before operation) -> add Finite Conductivity for Face part of Cylinder -> Connect via with ground.

Am I understanding this correctly? Or do I not need to subtract the Cylinder from the substrate?

[GioF]

I don't understand your question. 

Create Cylinder -> assign Polymer -> Subtract Cylinder from Substrate (enable Clone tool objects before operation) -> add Finite Conductivity for Face part of Cylinder 

If you follow the order above you should be fine.