IC Package Encapsulation with Thinner Cross-Sections for Thermal Stress Relief
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Solution Overview
Problem
Integrated circuit (IC) packages face stress and reliability issues due to differing coefficients of thermal expansion between materials, leading to potential failure at the coupling point with a package substrate or circuit board.
Innovation Solution
The IC package configurations include thinner cross-sectional areas, achieved through shaping the encapsulation material with features like trenches or beveled edges, which reduce rigidity and alleviate stress caused by thermal expansion, while maintaining sufficient rigidity for package placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the IC package uses uniform thickness encapsulation material, then the package has sufficient structural strength, but the stress concentration at coupling points increases due to differential thermal expansion
Solution Approach 1:
The encapsulation material is configured with non-uniform thickness, featuring thinner regions at specific locations and thicker regions at other locations. This local variation in thickness creates corresponding variations in rigidity, allowing the package to flex differentially at thinner regions to accommodate thermal expansion stresses, while thicker regions maintain structural strength. This resolves the contradiction by making different parts of the same component have different mechanical properties tailored to their functional requirements.
2Reliability
If the encapsulation material thickness is reduced at certain areas, then the rigidity is reduced to alleviate thermal stress, but the structural strength may be compromised
Solution Approach 1:
The encapsulation material implements localized thickness variations where specific regions are thinner to reduce rigidity and alleviate thermal stress through increased flexibility, while other regions maintain greater thickness to preserve structural strength. This spatial differentiation of mechanical properties allows simultaneous optimization of both stress relief and structural integrity.
Solution Approach 2:
The encapsulation material is effectively segmented into regions of different thicknesses, creating distinct functional zones: thinner regions serve as stress-relief zones with higher flexibility, while thicker regions serve as structural support zones. This segmentation allows the single encapsulation component to perform multiple mechanical functions simultaneously.
3Strength
If the IC package has high rigidity, then the package maintains structural integrity, but the stress from thermal expansion cannot be relieved, leading to coupling failure
Solution Approach 1:
The encapsulation material features non-uniform thickness distribution that creates local variations in rigidity. Thinner regions provide flexibility to relieve thermal expansion stresses through controlled flexing, while thicker regions maintain overall structural integrity. This local differentiation allows the package to simultaneously achieve both structural strength and stress relief capabilities.
Solution Approach 2:
The physical parameter of encapsulation material thickness is varied spatially to change the rigidity parameter locally. By adjusting the thickness parameter in different regions, the package achieves differential rigidity that enables stress relief in flexible zones while maintaining structural integrity in stiffer zones, thereby mitigating thermal stress effects.
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
This configuration enhances the reliability of package connections by reducing stress on interconnect structures and extending the number of temperature cycling cycles before failure, as demonstrated by simulated tests.
Implementation Method 1
one or more cross-section areas of the IC package may be thinner than one or more other cross-section areas... reduce rigidity of the IC package... alleviate stress caused by thermal expansion
Implementation Method 2
Each of these materials, in an IC package, a package substrate, or a circuit board, may have varying coefficients of thermal expansion. As the temperature of the various materials change the stresses imposed on the IC package, package substrate, or circuit board may change as well.
Data Source
AI summary
Embodiments of the present disclosure are directed towards an integrated circuit (IC) package including a die having a first side and a second side disposed opposite to the first side. The IC package may further include an encapsulation material encapsulating at least a portion of the die and having a first surface that is adjacent to the first side of the die and a second surface disposed opposite to the first surface. In embodiments, the second surface may be shaped such that one or more cross-section areas of the IC package are thinner than one or more other cross-section areas of the IC package. Other embodiments may be described and/or claimed.