Stacked Chip Package With Inclined RDL Routing for Reliable Interconnects

The patent transitions from planar arrangement of multiple dies on the same PCB side to a three-dimensional stacked configuration where dies are arranged vertically along the Z-axis. This dimensional change allows electrical connections to be achieved through vertical interconnections rather than horizontal wire-bonding, dramatically reducing the chip package area while maintaining electrical connectivity.

The patent implements a nested structure where multiple dies are stacked vertically, with each die positioned above the previous one. The under-bump metallization layers and conductive structures are nested between the dies, creating a compact vertical integration similar to nested dolls. This nesting approach minimizes the horizontal footprint while accommodating multiple functional dies.

The patent extracts and eliminates the wire-bonding process from the interconnection methodology. Instead of using wire-bonds to connect dies to the PCB, the invention employs direct solder bump connections and under-bump metallization layers that provide more reliable electrical pathways. This extraction of wire-bonding removes the associated reliability issues and volume occupation.

The patent replaces the mechanical wire-bonding system with a metallurgical bonding system using solder bumps and under-bump metallization. This substitution transitions from mechanical wire attachment to a more robust metallurgical connection that offers higher reliability and reduced volume, as the metallurgical bonds are inherently stronger and more stable than wire bonds.

The patent segments the molding material into distinct regions: a first molding material covering the lateral surfaces of the stacked dies, and a second molding material filling the space between the conductive structure and the first molding material. This segmentation allows for optimized material properties and structural support in different regions, reducing stress concentration and preventing redistribution layer breakage while maintaining die protection.

The patent applies different materials and structural properties to different regions of the package. The first molding material provides lateral protection with specific mechanical properties, while the second molding material provides support in the vertical gap region. This local differentiation of material quality optimizes both protection and stress distribution, preventing redistribution layer failure.