Via In Pad (Active Pad)

This process is becoming more and more common as BGA packages are becoming tighter. Rather than using the standard “dog bone” land pattern to transfer signal from the BGA footprint to a via that passes signal to other layers, vias can be drilled directly into the BGA footprint pads. This allows much simpler routing by soldering directly over the via. Make sure this process is called out in your fab notes.

TIP : We need to know the location, qty and size of the holes that need to be Via In Pad. The following steps are taken in this process.
1.Drill the via (thru hole or blind)
2.Fill the via with non-conductive material. Conductive material can be used but it's not recommended since conductive material expands much more quickly than the surrounding laminate when heated which can cause cracks and pad failures during the assembly process.
3.The surface of the plugged via is then plated over with copper.
4.The newly plated copper surface is flattened and smoothed (planarized) to be even with the surrounding copper features.
5.The final finish is applied
6.You now have a solderable surface mount pad that also passes signal to inner layers eliminating the need to rout the signal to a via on the surface layer.

Via Tenting, Plugging, and Filling

Section

1.Via Tenting

2.Mask (LPI) Plugged Vias (Non-Conductive Fill)

3.Via In Pad (Active Pad)

4.Conductive vs Non-Conductive Filled Vias