Semiconductor Package Stiffener Ring for CTE Warpage Control
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Solution Overview
Problem
The mismatch in Coefficients of Thermal Expansion (CTE) between different materials in semiconductor devices leads to warpage during thermal processes, causing issues such as shorting or open circuits when bonding to a printed circuit board.
Innovation Solution
The implementation of a stiffener structure, such as a ring, lids, or frame, made from materials with appropriate CTE, is placed on the circuit substrate to constrain and compensate for the warpage, with varying structural strengths along different directions to mitigate the warpage effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a stiffener structure is added to reduce warpage, then warpage reduction is achieved, but device complexity increases
Solution Approach 1:
The stiffener structure is divided into multiple segments or sections that can be independently configured. Each segment provides localized support where needed, reducing overall warpage while minimizing the total amount of material and structure required, thus balancing warpage reduction with device complexity
Solution Approach 2:
The stiffener structure implements varying structural strengths at different locations and orientations. The structure provides greater stiffness in directions where warpage is more severe, while maintaining lower stiffness in other directions, achieving effective warpage control with optimized material usage and reduced overall complexity
2Stability of the object's composition
If stiffener structure with high structural strength is used, then warpage control is improved, but over-compensation of CTE mismatch occurs
Solution Approach 1:
The stiffener structure implements spatially varying mechanical properties with different stiffness levels in different regions and orientations. This gradient structure provides just enough support to control warpage without creating excessive stiffness that would prevent natural thermal expansion compensation, thereby avoiding over-compensation of CTE mismatch
Solution Approach 2:
The stiffener structure is designed with controlled flexibility that allows it to dynamically adapt to thermal expansion forces. The structure maintains rigidity sufficient to control warpage during bonding processes while retaining enough compliance to accommodate normal thermal cycling and CTE mismatch without causing stress concentration or failure
3Reliability
If stiffener structure is added to constrain warpage, then bonding reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The stiffener structure is integrated with the packaging substrate or housing as a unified component rather than being added as a separate part. This merging of functions reduces the number of assembly steps, eliminates additional fastening operations, and simplifies manufacturing while still providing the necessary warpage control for reliable bonding
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 stiffener structure effectively reduces warpage by providing opposing forces to the circuit substrate, ensuring stable bonding to the printed circuit board and preventing over-compensation of CTE mismatch, thus enhancing the reliability of semiconductor devices.
Implementation Method 1
The mismatch in Coefficients of Thermal Expansion (CTE) between different materials and different package components, such as different material between the packaging substrate and the semiconductor dies
Data Source
AI summary
A semiconductor device including a circuit substrate, a chip package, and a stiffener ring is provided. The chip package is disposed on and electrically connected to the circuit substrate, the chip package includes a pair of first parallel sides and a pair of second parallel sides shorter than the pair of first parallel sides. The stiffener ring is disposed on the circuit substrate, the stiffener ring includes first stiffener portions extending along a direction substantially parallel with the pair of first parallel sides and second stiffener portions extending along the direction substantially parallel with the pair of second parallel sides. The first stiffener portions are connected to the second stiffener portions, and the second stiffener portions is mechanically weaker than the first stiffener portions. A semiconductor device including stiffener lids is also provided.