eCADSTAR - Routing Vias Non-Functional Lands

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Video Transcript

In this video we are going to focus on eCADSTAR's flexibility regarding none functional lands.

If you’re not familiar with the phrase none functional lands all we are referring to are pads on internal layers that have no connection.  The barrel of the hole will be out plated electrical connection between any layer transitions. So the pads on layers where no connection exists are unnecessary features.

In this example, you can see that we have pads on every layer. The outmost layers, 1 and 8 also have tracks. But that’s irrelevant. Pads on the external layers will always be needed for the fabrication process. The only other real connection we have is on this via is on layer 3. Removal of those none functional lands aids the fabrication process and gives you the designer more real estate in which to work.

 

So lets look at how we can deploy this in the PCB environment.

If you’re unfamiliar with eCADSTAR, what we can see here is we have our 2D view and our 3D view.  eCADSTAR allows both 2D and 3D to operate in real-time. So it really gives you a good insight into how your Padstacks are being managed.

In this first example, I deviate from my standard, my preference which is to not have none functional lands included. So I have to change my padstack. I’m using my touchscreen interface to make the change but you can drag your cursor over to this. You can configure them at net level. You can configure them at net class level.  We can also define rule areas that will change the via automatically for us.

 

Now the via is added with all pads on all layers.  As you can see when I move on to the second via it defaults back to my preference which is to not have the none functional lands included. Now when I make connections on the second via you will see it will only add a pad as and when a connection is needed. As I remove traces the Padstacks are also removed.

Let me just drop down into the library and show you how we configure those pads. It's really simple. Two geometrically identical Padstacks have been configured here for use as vias. One has a pad defined for internal layers and one doesn’t. Back in our PCB editor lets take a quick look at how that might work within a rule area.

So this design could be a flexi-rigid design. The area where you can see the LED clock matrix could be on the flexi material and in which case the flexible material would benefit from the vias actually having the none functional lands because they act as support. 

But outside of that area I want my preferred method of having them removed.  So I use a rule area. I use fan out with via in pad permitted and I route on an internal layer. As I transition the areas the preferred via is used. So lots of flexibility regarding via configurations and these are just eCADSTARS standard via configurations outside of blind and buried, stacked vias and spiral vias.

So, remember, none functional lands. Inclusion or exclusion. Review your board requirements. Define your preference by design rather than post-event. It will save you and your PCB fabricator time.

 

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