Definition

Via-in-pad places a via directly within a surface-mount component pad rather than adjacent to it (dog-bone style). This technique is essential for fine-pitch BGAs (≤0.5mm) and QFNs where space between pads is insufficient for fan-out vias. Via-in-pad requires the via to be plugged with non-conductive epoxy, then capped with copper plating to create a flat, solderable surface (VIPPO process). Without plugging, solder wicks into the via during reflow, causing voids and weak joints. Via-in-pad adds 15-25% to fabrication cost but enables higher density and better thermal paths.