Interposer With Opening For Die Stacking

An interposer is introduced as an intermediary component between the substrate and the stacked dies. The interposer has a first surface that couples to the substrate and a second surface that supports multiple dies in stacked arrangement. This intermediary structure enables die stacking capability while managing the complexity by providing a dedicated interface layer that handles the interconnections between dies and substrate.

The patent transitions from a conventional planar single-die package to a three-dimensional stacked die configuration. By utilizing the vertical dimension (z-axis) for stacking multiple dies on top of each other on the interposer, the package achieves higher interconnect density and enables multiple IC functions in a single package without simply expanding the lateral footprint.

The interposer serves as a mediator that provides bond pads on its first surface for direct coupling to the substrate. This arrangement allows wire bonds to connect from the substrate bond pads to the interposer bond pads with minimal loop height, and then vertical interconnections are achieved through the interposer structure itself rather than through long wire loops between stacked dies.

The interconnection system is segmented into two parts: horizontal connections from substrate to interposer using wire bonds with controlled loop height, and vertical connections within the interposer that support multiple dies. This segmentation allows optimization of wire loop height for the substrate interface while achieving high interconnect density through the stacked die configuration on the interposer.

The interposer acts as a mechanical intermediary and support structure for the stacked dies. It provides a stable platform that distributes mechanical stresses and prevents direct contact between stacked dies, thereby reducing the risk of die breakage when larger dies are stacked on smaller ones. The interposer's structure absorbs and distributes the mechanical loads, protecting the fragile die structures.

The interposer provides beforehand cushioning by serving as a protective support layer between the substrate and the stacked dies. This cushioning effect is built into the package structure in advance, preventing mechanical damage to the dies during assembly and operation, particularly when larger dies are stacked on smaller ones where stress concentration could occur.