IC Package Cavity Barrier Prevents Underfill Delamination
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Solution Overview
Problem
The mechanical stress caused by underfill capillary flow in integrated circuit packages with different coefficients of thermal expansion (CTE) leads to delamination issues between components.
Innovation Solution
A barrier structure is formed around a second integrated circuit die to create a cavity devoid of underfill material, preventing underfill material from entering and minimizing shear stress between dies and the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If underfill material is dispensed between the components in the package to increase structural stability, then the package's structural stability is improved, but mechanical stress increases leading to delamination between integrated circuit components with different CTE values
Solution Approach 1:
The patent applies local quality by creating a differentiated structure where different regions of the package have different properties. Specifically, a barrier structure is formed around the second die to create a cavity that excludes underfill material, while underfill is present in other regions. This localized variation in material distribution allows the package to have both structural stability (where underfill is present) and reduced mechanical stress (where underfill is excluded), resolving the contradiction between these two requirements.
2Stability of the object's composition
If underfill material is dispensed between the components in the package to increase structural stability, then the package's structural stability is improved, but delamination occurs between integrated circuit components with different CTE values
Solution Approach 1:
The patent creates different material environments in different locations: underfill material is present in regions requiring structural stability but excluded from the cavity surrounding the second die where delamination risk is highest. This localized differentiation allows the package to maintain overall structural stability while protecting critical interfaces from delamination caused by CTE mismatch.
3Stress or pressure
If a barrier structure is formed to create a cavity devoid of underfill material, then mechanical stress resistance is improved, but device complexity increases
Solution Approach 1:
The patent segments the package into distinct regions: a cavity region surrounding the second die that is excluded from underfill material, and other regions where underfill is present. The barrier structure acts as a segmenting element that separates these regions. This segmentation approach achieves reduced mechanical stress at critical interfaces while maintaining structural stability elsewhere, with the added benefit of potentially simplifying the overall package design by addressing stress issues locally rather than requiring complex global redesign.
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 approach enhances mechanical stress resistance and reduces surface delamination by eliminating underfill material from the interface between dies with different CTE values, thereby improving the structural stability of the integrated circuit package.
Implementation Method 1
When an underfill material is dispensed between the components in the package, the underfill capillary flow may increase mechanical stress in the package
Data Source
AI summary
Integrated circuit packages with cavity are disclosed. A disclosed integrated circuit package includes a first die. A second die may be coupled to the first die by attaching the first die to a top surface of the second die. A blocking element such as a barrier structure may be formed that surrounds the second die. A cavity may be formed between the blocking element and the first die that encloses the second die. The barrier structure may help prevent underfill material from entering the cavity during underfill deposition processes. A heat spreading lid may cover the first die, second die and package substrate.