Interposer-Based Multi-Die Packaging for Fine Pitch Connections
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Solution Overview
Problem
The existing package on package (PoP) technology faces challenges in achieving finer pitch connections between semiconductor devices due to the stand-off distance required for solder balls, which limits the size of the processor and increases packaging costs, while also constraining the thickness of the bottom package.
Innovation Solution
The use of an interposer between stacked semiconductor packages provides sufficient space for components, allowing for smaller solder balls and finer pitch connections by determining the space between packages, thereby enabling more compact and cost-effective device designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solder balls are used for connections between stacked packages, then electrical connections are established, but the stand-off distance required limits the pitch and increases package thickness
Solution Approach 1:
The patent introduces an interposer substrate as an intermediary component between the bottom and top packages. This interposer carries fine-pitch solder balls that connect to the bottom package, while coarser-pitch solder balls on the interposer connect to the top package. This mediator allows fine-pitch connections without requiring the entire package stack to have the corresponding fine stand-off distance, thus resolving the contradiction between pitch and package thickness.
2Manufacturing precision
If finer pitch connections are achieved with smaller solder balls, then connection density increases, but the stand-off distance becomes insufficient
Solution Approach 1:
The interposer substrate serves as a mediator that enables fine-pitch connections through its fine-pitch solder balls while maintaining connection reliability through multiple connection layers. The fine-pitch solder balls provide dense connections between the interposer and bottom package, while the coarser-pitch solder balls provide robust connections to the top package, thus achieving both fine pitch and reliable connections.
Solution Approach 2:
The patent transitions from a two-dimensional planar connection approach to a three-dimensional stacked connection approach. By utilizing vertical stacking with an interposer substrate, the system achieves fine-pitch connections in the horizontal plane while maintaining adequate stand-off distances in the vertical dimension, effectively adding a spatial dimension to resolve the pitch-reliability trade-off.
3Reliability
If the bottom package thickness is increased to accommodate larger solder balls, then stand-off distance is sufficient, but device size increases
Solution Approach 1:
The interposer substrate acts as a mediator that decouples the relationship between solder ball size and package thickness. The interposer carries the fine-pitch solder balls that determine the connection density, while the coarser-pitch solder balls on the interposer provide robust connections to the top package without requiring increased bottom package thickness. This mediator enables reliable connections with compact device dimensions.
Data Source
AI summary
A semiconductor device assembly includes an interposer having an opening extending from a first major surface to a second major surface of the interposer and a plurality of external connectors on the second major surface. The first major surface of the interposer is attached to a packaged semiconductor device. The opening of the interposer exposes the packaged semiconductor device.