Q: What is the correct via-in-pad design for BGA and high-density PCB layouts?
Answer
Via-in-pad (VIP) is essential for BGA escape routing: thermal vias non-conductive filled (epoxy fill) and capped or conductive fill. Thermal vias under BGA pads: 0.3-0.4 mm diameter 1 mm pitch connect to plane below with tenting (solder mask covering) to prevent solder wicking. For RF or power BGAs use plugged and plated (PIP) thermal vias with non-conductive fill. For high-frequency boards (>1 GHz) avoid vias in the signal path within 2 mm of the BGA ball – use blind/buried microvias. Via stub resonance can be eliminated by back-drilling. In Altium/KiCad configure via tenting in design rules.
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