Beveled Two-Piece Stiffener Structure for Chip Package Delamination
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Solution Overview
Problem
The increasing power consumption and thermal regulation challenges in semiconductor dies lead to warping and delamination issues within chip package structures, causing cracks and disconnects in wiring interconnect layers and components.
Innovation Solution
A beveled stiffener structure is implemented on the package substrate, featuring a bottom portion with a tapered top surface and a top portion with a tapered bottom surface, enhancing adhesive layer application and reducing delamination risk through increased surface area and optimized thermal expansion coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional flat stiffener structure is used, then the manufacturing process is simple, but the adhesive layer has insufficient bonding area leading to delamination under thermal stress
Solution Approach 1:
The stiffener structure incorporates beveled surfaces with specific taper angles (e.g., 45 degrees) instead of flat surfaces. This curvature/angulation increases the adhesive bonding area and improves stress distribution, directly resolving the delamination issue while maintaining manufacturing feasibility through standard beveling processes.
Solution Approach 2:
The invention transitions from a two-dimensional flat stiffener top surface to a three-dimensional beveled surface structure. This dimensional change creates additional bonding surface area and allows the adhesive layer to engage more effectively with the overlying layers, preventing delamination without significantly complicating the manufacturing process.
2Reliability
If the stiffener structure uses uniform material composition, then the manufacturing process is simple, but thermal expansion mismatch causes delamination at temperature extremes
Solution Approach 1:
The stiffener structure uses a composite material system where different layers have different coefficients of thermal expansion (CTE). The first stiffener layer has a lower CTE than the second stiffener layer, allowing each layer to compensate for thermal stress differently. This local differentiation of material properties prevents delamination during thermal cycling while maintaining overall structural integrity.
Solution Approach 2:
The invention employs a composite stiffener structure with multiple layers of different materials (e.g., copper layer and aluminum layer) that have complementary properties. The copper layer provides low CTE for dimensional stability, while the aluminum layer provides higher CTE for thermal stress accommodation. This composite approach solves the thermal expansion mismatch problem without requiring complex single-material solutions.
3Reliability
If a single-piece stiffener structure is used, then the manufacturing process is simple, but the structure cannot provide optimized stress distribution and thermal management
Solution Approach 1:
The stiffener structure is divided into multiple separate layers (first stiffener layer and second stiffener layer) that can be independently manufactured and then bonded together. This segmentation allows each layer to be optimized for specific functions (stress distribution, thermal management) while maintaining manufacturing simplicity through modular construction processes.
Solution Approach 2:
An adhesive layer is introduced as an intermediary between the first and second stiffener layers. This adhesive mediator not only bonds the layers together but also provides additional functionality in stress distribution and thermal management. The beveled surfaces of the stiffener layers further enhance the adhesive bonding area, ensuring reliable interlayer connection.
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 beveled stiffener structure provides increased structural support and reduces delamination risk by distributing shear stress, thereby improving the integrity of the chip package structure.
Implementation Method 1
The beveled stiffener structure provides increased structural support and reduces delamination risk by distributing shear stress
Implementation Method 2
a second adhesive layer may be deposited on the tapered top surfaces to attach the top portion to the bottom portion
Data Source
AI summary
Devices and methods for forming a chip package structure including a package substrate, a first adhesive layer attached to a top surface of the package substrate, and a beveled stiffener structure attached to the package substrate. The beveled stiffener structure may include a bottom portion including a tapered top surface, in which a bottom surface of the bottom portion is in contact with the first adhesive layer, a second adhesive layer attached to the tapered top surface, and a top portion including a tapered bottom surface, in which the tapered bottom surface is in contact with the second adhesive layer. The tapered top surface and the tapered bottom surface have a taper angle between 5 degrees and 60 degrees with respect to a top surface of the package substrate.