3D Package Structure With Dummy Corners for Delamination Resistance
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Solution Overview
Problem
Current wafer-level packaging technologies face challenges in managing thermal expansion and contraction, leading to delamination and cracking issues in 3D packaging and 3DIC devices, particularly due to the mismatch in coefficients of thermal expansion between encapsulants and semiconductor dies and redistribution structures.
Innovation Solution
Incorporating a dummy structure with a higher Young's modulus and lower coefficient of thermal expansion, positioned between the die and through vias, and adjacent to the die's corners, to mitigate stress and improve delamination resistance, along with a redistribution structure and encapsulant that are electrically connected to the die and vias, and using a release layer for carrier substrate de-bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer-level packaging is used to achieve high-density integration, then productivity and miniaturization are improved, but thermal expansion mismatch causes delamination and cracking
Solution Approach 1:
A dummy structure is introduced as an intermediary element positioned between the die and through vias. This dummy structure acts as a stress buffer that absorbs thermal expansion mismatch, preventing direct stress transmission between the encapsulant and the die/through vias interface, thereby reducing delamination and cracking while maintaining wafer-level packaging density
Solution Approach 2:
The dummy structure is designed with specific material parameters (higher Young's modulus, lower coefficient of thermal expansion) that differ from both the die and encapsulant materials. By changing the mechanical and thermal parameters of the intermediate structure, the system accommodates thermal expansion differences and reduces stress concentration at critical interfaces
2Reliability
If through vias are used to achieve electrical connectivity, then electrical connection is improved, but stress concentration at via corners increases delamination risk
Solution Approach 1:
The dummy structure is positioned beforehand adjacent to the corners of through vias, creating a protective buffer zone before thermal stress can concentrate at the via corners. This preemptive cushioning absorbs and distributes the thermal expansion stress, preventing stress concentration that would otherwise lead to delamination at the via-die interface
3Area of stationary object
If die corners are left exposed to achieve compact layout, then area is reduced, but stress concentration at corners causes cracking
Solution Approach 1:
Instead of uniformly protecting the entire die perimeter, dummy structures are selectively placed only at critical corner regions where stress concentration occurs. This localized approach provides crack resistance at high-stress areas while maintaining compact overall package area, as the dummy structures extend only as far as needed to protect the corner regions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces tensile stress and enhances the reliability of the package by minimizing delamination and cracking, improving the overall structural integrity and reliability of the 3D packaging structure.
Implementation Method 1
mismatch in coefficients of thermal expansion between encapsulants and semiconductor dies
Implementation Method 2
dummy structure with a higher Young's modulus and lower coefficient of thermal expansion
Data Source
AI summary
Disclosed are a package, a package structure and a method of manufacturing a package structure. In one embodiment, the package includes a die, a plurality of through vias, at least one dummy structure, an encapsulant and a redistribution structure. The plurality of through vias surround the die. The at least one dummy structure is disposed between the die and the plurality of through vias and adjacent to at least one corner of the die. The encapsulant encapsulates the die, the plurality of through vias and the at least one dummy structure. The redistribution structure is disposed on the die, the plurality of through vias, the at least one dummy structure and the encapsulant and electrically connected to the die and the plurality of through vias.