Overpass Dice Stacked Architecture for SiP Z-Height Reduction
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Solution Overview
Problem
System in package (SiP) devices face challenges in miniaturization to improve connectivity and manufacturing efficiency, particularly in achieving lower z-heights and integrating radio-frequency components while managing signal integrity and heat effectively.
Innovation Solution
The implementation of a low-profile 3D overpass die stacked architecture, where overpass dice are mounted on a package substrate with backside recesses that straddle landed dice, utilizing through-silicon vias (TSVs) and RF shielding to reduce z-height, enhance signal integrity, and manage heat through controlled spacing and fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional stacked architecture is used, then connectivity is improved, but z-height cannot be reduced sufficiently
Solution Approach 1:
The patent transitions from traditional vertical stacking to a lateral overpass configuration where dice are connected through horizontal vias in the same plane. This dimensional change allows signals to travel laterally through the substrate rather than vertically through stacked interfaces, reducing z-height while maintaining connectivity reliability through extended via structures that traverse the substrate thickness.
Solution Approach 2:
The substrate acts as an intermediary element that enables lateral connections between dice. Through-silicon vias (TSVs) embedded in the substrate serve as conductive pathways that mediate signal transmission between overpass dice and landed dice without requiring direct vertical stacking, thus reducing overall package height while preserving signal integrity.
2Productivity
If miniaturization is pursued to improve connectivity, then device density increases, but heat management becomes more difficult
Solution Approach 1:
The patent extracts heat-generating components (overpass dice) from direct contact with the substrate and positions them in an overpass configuration. This spatial separation allows heat to be dissipated through lateral pathways and fluid flow channels integrated into the substrate, preventing heat accumulation while maintaining high device density through efficient space utilization.
Solution Approach 2:
The patent incorporates fluid flow channels within the substrate structure to actively manage heat removal. Coolant flow through these channels provides thermal management capability, enabling high device density by continuously extracting heat from compacted components without compromising thermal performance.
3Length of moving object
If overpass dice are implemented to reduce z-height, then signal integrity may deteriorate due to channel impedance discontinuities
Solution Approach 1:
The patent optimizes via dimensions, substrate material properties, and trace geometry to maintain consistent impedance throughout the signal path. By carefully controlling via diameter, length, and spacing, as well as substrate thickness and dielectric constants, the design achieves impedance matching that minimizes reflections and discontinuities despite the lateral routing topology.
Solution Approach 2:
The patent employs composite substrate structures with optimized dielectric layers and conductive via materials to maintain signal integrity. The use of low-loss dielectric materials and high-conductivity via fill materials reduces signal attenuation and impedance variations, ensuring reliable signal transmission through the lateral overpass configuration.
4Adaptability or versatility
If RF components are integrated to improve connectivity, then device functionality increases, but interference issues arise
Solution Approach 1:
The patent implements nested shielding structures where RF components are enclosed within grounded cavities or shielded regions formed by substrate layers and via walls. This nested configuration contains electromagnetic fields within designated areas, preventing interference between adjacent RF and non-RF components while enabling diverse device functionality through selective RF integration.
Solution Approach 2:
The patent extracts RF components from shared substrate regions and isolates them in dedicated zones with specialized grounding and shielding. This spatial separation removes sources of electromagnetic interference from sensitive areas, allowing RF functionality to be integrated without compromising the performance of other device components.
Data Source
AI summary
A system in package device includes an overpass die on a package substrate and the overpass die includes a recess on the back side in order to straddle a landed die also on the package substrate. The recess is bounded by at least two overpass walls. Communication between the dice is done with a through-silicon via and communication between the overpass die and the package substrate is also done with a through-silicon via.