how to define DRC for VIP?

[eric_engineer]

How do you set DRC up to allow for VIP (Via in pad)?  I dropped a via on a BGA pad and it placed fine, but now DRC is complaining about overlap.

Thank you.

[jorge_garcia]

Hi @eric_engineer,

I hope this message finds you well. You don't have to pre-place the vias for via in pad. Within Fusion 360 Electronics we do Via in Pad using micro-vias. The key to setting these up is to go into the DRC > Sizes tab and set the min Micro Via size. It MUST be less than the minimum drill in order to enable the micro-vias functionality. Additionally, you need to have a via configuration for micro-vias in the layer stackup manager. Once that is setup then you can drop VIPs as you route. 

Start a route at the BGA ball, then press ctrl+shift, select the layer you want to transition to and click OK. Then left click to drop the via at the center of the ball and then keep routing from there.

Let me know if you run into problems.

Best Regards,

[eric_engineer]

Alright I get that is all Fusion can do, but I'm not using micro-vias on these boards for cost.  All VIP will be drill holes with the same size as the vias.  If I switch to micro-vias is the tool going to generate a separate drill table for these then?

[jorge_garcia]

Hi @eric_engineer,

Thabks for the followup. Let me ask for a clarification here. Are the VIPs going to be blind vias or you intend to just use a through hole via for everything.

You can trick the system by temporarily increasing the min drill and increasing the microvias to be whatever the drill size you want to use.

Additionally if its just going to be your normal through hole vias you should still be able to place the via directly on the center of the pad.

Let me know if there's anything else I can do for you.

Best Regards,

[eric_engineer]

For this board the VIPs are through-hole drills (they will be filled and over-plated flat later).  

Additionally if its just going to be your normal through hole vias you should still be able to place the via directly on the center of the pad.

I have seen that work sometimes, like on a cap.  But here on my BGA there is only the pad and the VIA and it's throwing an overlap DRC.

[eric_engineer]

I don't follow how the "trick the system" approach works?  I've come back to see if I can fix all these DRC errors.

[jorge_garcia]

Hi @eric_engineer ,

I hope you're doing well. The idea would be to increase min drill and then bump up the micro-via to whatever you really want the micro via to be.

If you run the DRC, what is the specific error it gives you for the BGA balls?  As an aside the diameter of the vias ends up being larger than the ball itself, could lead to problems since you are loosing routing area between the BGA pads. 

Just an observation.

Best Regards,