Semiconductor Package Stiffener Layout for CTE-Induced Warpage
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Solution Overview
Problem
Warpage and stress occur in semiconductor devices during thermal processes due to mismatched Coefficients of Thermal Expansion (CTEs) between different materials and package components, leading to potential shorting or open circuits.
Innovation Solution
The implementation of stiffener structures, such as stiffener rings, lids, and frames, made from materials with appropriate CTEs, are placed on the circuit substrate to constrain and compensate for the warpage caused by CTE mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple semiconductor dies and electronic components are mounted on a packaging substrate and bonded to a PCB through a thermal process, then the semiconductor device can be formed with multiple functional components, but warpage and stress occur due to mismatched Coefficients of Thermal Expansion (CTEs) between different materials
Solution Approach 1:
The patent applies local quality by creating a stiffener structure with non-uniform thickness distribution. The stiffener has a first thickness in a first region and a second thickness in a second region, where the thickness varies to provide different levels of structural support in different areas. This localized variation in mechanical properties compensates for the non-uniform CTE mismatch across the packaging substrate, reducing warpage while maintaining the ability to mount multiple components.
Solution Approach 2:
The patent employs composite materials by combining the packaging substrate with a stiffener structure made of a different material having distinct mechanical and thermal properties. The stiffener material is specifically selected to have CTE characteristics that compensate for the CTE mismatch between the substrate and mounted components. This composite construction creates a balanced structure that resists warpage during thermal bonding while supporting multiple semiconductor dies and electronic components.
2Stability of the object's composition
If a stiffener structure with varying thickness is implemented to compensate for CTE mismatch, then warpage is reduced, but the device complexity increases
Solution Approach 1:
The stiffener structure implements local quality through its spatially varying thickness profile. The first thickness in the first region and the second thickness in the second region are strategically designed to match the local warpage tendencies caused by CTE mismatch. This localized approach allows effective warpage compensation without requiring a completely complex multi-component system, as the variation is achieved within a single integrated stiffener element.
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 structures effectively reduce warpage and stress in semiconductor devices, ensuring reliable bonding to printed circuit boards by compensating for the CTE mismatch between different components.
Implementation Method 1
Warpage and stress may occur during the thermal process due to the mismatch in Coefficients of Thermal Expansion (CTEs) between different materials and different package components
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.