Enlarged Through-Vias in Encapsulant for Stable Metal Posts
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Solution Overview
Problem
Conventional semiconductor packaging technologies face challenges in integrating a high number of I/O pads due to limited pitch and solder bridge issues, especially in fan-in packages, which restricts the number of solder balls and increases packaging complexity.
Innovation Solution
The formation of enlarged through-vias and dummy through-vias in the encapsulant, along with a redistribution layer structure, to stabilize metal posts during plating mask removal and enhance the packaging process, allowing for increased I/O pad density and reduced tilting/falling of metal posts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pitch of I/O pads is decreased to increase density, then the number of I/O pads increases, but solder bridges may occur
Solution Approach 1:
The patent divides the I/O pad array into multiple sub-arrays with different orientations (e.g., first array in one direction, second array in another direction). This segmentation allows for better spatial distribution of pads, maintaining adequate spacing to prevent solder bridges while increasing overall pad density on the die surface.
Solution Approach 2:
The patent transitions from conventional two-dimensional pad arrays to a three-dimensional configuration by stacking multiple arrays at different orientations and potentially different heights. This dimensional change enables higher I/O pad density without reducing the pitch within each array, thereby avoiding solder bridge issues while achieving increased connectivity.
2Ease of manufacture
If fan-in packaging is used to maintain small die size, then manufacturing cost is reduced, but the number of I/O pads is limited
Solution Approach 1:
The patent employs multi-oriented arrays arranged in three-dimensional space, allowing I/O pads to be distributed across multiple planes and angles. This enables fan-in packages to achieve higher I/O pad counts without increasing die area, maintaining cost-effectiveness while overcoming the limitation of traditional planar pad layouts.
Solution Approach 2:
The patent nests multiple I/O pad arrays within the confined die area by orienting them in different directions and stacking them vertically. This nested arrangement maximizes the utilization of available die space, enabling a higher number of I/O pads to be integrated into small-form-factor fan-in packages without increasing manufacturing complexity.
3Device complexity
If metal posts are formed in encapsulant without enlarged through-vias, then manufacturing process is simplified, but metal posts may tilt or fall during plating mask removal
Solution Approach 1:
The patent performs preliminary actions by forming enlarged through-vias and dummy through-vias in the encapsulant before completing the metal post formation process. These enlarged structures are prepared in advance to provide mechanical support and stability, preventing metal posts from tilting or falling during subsequent plating mask removal operations.
Solution Approach 2:
The patent implements beforehand cushioning by creating enlarged through-vias with larger cross-sectional areas that can accommodate and support the metal posts during the plating process. These enlarged vias act as cushioning structures that absorb mechanical stresses and prevent post instability, ensuring reliable metal post formation without requiring overly complex manufacturing processes.
Data Source
AI summary
A package includes a device die, an encapsulant encapsulating the device die therein, a first plurality of through-vias penetrating through the encapsulant, a second plurality of through-vias penetrating through the encapsulant, and redistribution lines over and electrically coupling to the first plurality of through-vias. The first plurality of through-vias include an array. The second plurality of through-vias are outside of the first array, and the second plurality of through-vias are larger than the first plurality of through-vias.