Dummy Pillars in Semiconductor Packages to Balance CTE Mismatch
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Solution Overview
Problem
Semiconductor package structures face warpage due to coefficient of thermal expansion (CTE) mismatch and yield reduction from large gaps between electronic components, which existing technologies fail to adequately address, especially with the challenge of forming high-density fine pillars within encapsulants.
Innovation Solution
A package structure incorporating dummy pillars of varying heights embedded within the encapsulant, which are formed before the encapsulant is applied, along with conductive pillars that replace solder balls to meet ultra-fine circuit design specifications and reduce warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of electronic components is increased to improve electrical performance and functions, then the integration density is improved, but warpage of the package structure increases due to CTE mismatch
Solution Approach 1:
The patent introduces dummy pillars with varying heights to modify the structural parameters of the package. These pillars compensate for CTE mismatch by creating a gradient structure that balances thermal expansion forces, thereby reducing warpage while maintaining high integration density of electronic components
Solution Approach 2:
The package structure employs a composite design combining dummy pillars of different materials or structures with the encapsulant and electronic components. This composite approach allows differential expansion compensation, where the dummy pillars act as stress buffers to maintain package stability under thermal cycling conditions
2Ease of manufacture
If large gaps between adjacent electronic components exist, then manufacturing is easier, but the encapsulant recesses to form dimples which decreases yield
Solution Approach 1:
The patent applies local quality by placing dummy pillars specifically in gap regions between electronic components. These localized structures fill the encapsulant recesses and prevent dimple formation, while not interfering with the placement and manufacturing of the main electronic components
Solution Approach 2:
Dummy pillars serve as intermediary structures between the encapsulant and the gap regions. They mediate the stress distribution and prevent the encapsulant from directly recessing into large gaps, thereby eliminating dimples without requiring changes to the electronic component layout or manufacturing process
3Productivity
If high-density fine pillars are formed to meet ultra-fine circuit design specifications, then I/O count increases, but manufacturing complexity increases
Solution Approach 1:
The dummy pillars are formed preliminarily before the encapsulant is applied, using standard semiconductor fabrication processes. This preliminary formation simplifies subsequent manufacturing steps, as the pillar structures are already in place to guide encapsulant flow and prevent dimple formation during molding
Solution Approach 2:
The patent segments the package structure into distinct functional zones: electronic component regions, dummy pillar regions in gaps, and encapsulant regions. This segmentation allows each zone to be optimized independently, with dummy pillars handling gap-filling functions and electronic components handling I/O functions, thereby managing manufacturing complexity through functional decomposition
Data Source
AI summary
A package structure includes a base material, at least one electronic device, at least one encapsulant and a plurality of dummy pillars. The electronic device is electrically connected to the base material. The encapsulant covers the electronic device. The dummy pillars are embedded in the encapsulant. At least two of the dummy pillars have different heights.