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Artwork added this DRC at the request of a packaging client.

The client wanted a table of the effective pad capture diameter for vias between an RDL layer and the via opening. Since the RDL layout is very general, this effective capture diameter is computed as shown in the diagram below:

illustration of how the effective capture pad diameter is computed.

Let's see how this works.

We'll start by loading a package layout into Qckvu3 and then use the Plugins | DRC Tool menu pick to open the DRC dialog. Once the dialog is open, we'll select Capture Pad Size DRC from the drop down and select our parent layer to 29 (RDL) and our Child Layer to 50 (UBM).

DRC Dialog for Capture Pad Size

After pressing the Run DRC button, we should see the following report on screen.

You can see that the reported pad capture size is ~ 229.8 um.

Report for Capture Pad Size

Let's measure one manually to check the results:

measuring the pad diamter
measuring the pad diamter

We can see that the pad radius = 210/2 = 105 um and the min_clearance= 10.3 um

Capture Pad Size = 2 X (105 + 10.3) = 230.26 which matches up quite closely with the DRC report of 229.8 um.