Via Interconnect with Overhanging Head for Wiring Substrate Anchorage

The via interconnect is designed with a curved side surface that bulges outward from the cylindrical axis, transforming the simple cylindrical shape into a curved, mushroom-like structure. This curvature increases the contact area between the via interconnect and the insulating layer, providing mechanical interlocking that prevents pull-out while maintaining structural simplicity.

The invention extends the via interconnect structure from a one-dimensional cylindrical form into a two-dimensional expanded form at the top surface, creating a mushroom-like shape with a widened head. This dimensional change increases the anchorage area within the insulating layer without significantly increasing the overall height, thus improving reliability while keeping the structure relatively simple.

The via interconnect is designed with non-uniform cross-sectional area along its length, with the area being smaller at the bottom (embedded in insulating layer) and larger at the top (forming the mushroom head). This local variation in quality provides enhanced anchorage at the expanded top region while maintaining a narrower profile in the insulating layer, balancing anchorage strength with manufacturing control.

The curved side surface creates a gradual transition in cross-sectional area from the cylindrical stem to the expanded head, avoiding abrupt changes that would be difficult to manufacture. The smooth curvature allows for controlled material deposition or formation processes while achieving the desired non-uniform area distribution for optimal anchorage.