Package Substrate Window Vertical Interconnect Stacked IC

The patent transitions from a conventional two-tiered PoP configuration to a multi-layer stacked architecture with at least three tiers, utilizing vertical space more efficiently. This dimensional expansion allows multiple functional chips to be integrated within the same footprint area, thereby increasing packaging density without proportionally increasing overall package complexity.

The patent implements a nested structure where multiple functional chips are stacked vertically within a single package footprint. Each tier contains functional chips that are nested within the vertical space defined by the package substrate, allowing multiple devices to occupy the same horizontal area while maintaining electrical connectivity through vertical interconnections.

The patent incorporates alignment marks and positioning structures on the package substrate and interlayer insulation before chip mounting. These preliminary features guide the precise placement of functional chips on each tier, ensuring accurate alignment even as the number of stacked chips increases. The alignment marks are formed during substrate preparation, enabling subsequent chips to be positioned with high precision.

The patent uses an interlayer insulation layer as an intermediary structure between stacked functional chips. This insulation layer provides a stable mounting surface and includes through-insulation connectors that facilitate electrical connectivity while maintaining mechanical stability. The intermediary structure absorbs and compensates for minor dimensional variations, preserving alignment precision across multiple tiers.

The patent employs a composite package substrate comprising multiple layers with different material properties, including organic substrates and ceramic materials. This composite structure is designed with controlled thermal expansion coefficients and mechanical properties that compensate for warpage tendencies. The multi-layer composite construction provides internal stress balancing, reducing overall package warpage despite the reduced footprint and increased stacking density.

The patent implements localized reinforcement structures at critical regions of the package substrate, such as around mounting holes and chip attachment areas. These localized features provide additional structural support and warpage control where needed, while maintaining the overall reduced footprint. The package substrate includes strategically placed support pillars and stiffening ribs that address warpage issues locally without increasing overall package area.