How HDI Via Density Can Break Your Power Planes

Standard DRCs won’t flag power delivery failures that may be present in your HDI PCB. When you break out a dense BGA, every microvia introduces an anti-pad into your power and ground planes. For a 0.4mm BGA with hundreds of pins, these anti-pads accumulate into what's called the "Swiss cheese" effect. Anti-pad accumulation under fine-pitch BGAs reduces your plane's effective cross-section, increases impedance, adds inductance to your return paths, and drives up voltage drop between your decoupling caps and component power pins. Current density simulation makes this visible, where you can see the current being funneled through narrow copper bridges in the BGA region in real time. This is something DRC will never flag because technically, every clearance is valid. A continuous return path is non-negotiable and in HDI, it's harder than ever to maintain because fine-pitch BGAs force so many vias and anti-pads into the same concentrated area. The fix comes down to two strategies: reducing your anti-pad size so less copper is removed per via, and distributing staggered power and ground vias through the BGA field rather than just around the periphery. One placement decision that solves both power integrity and signal integrity at once.