Semiconductor Package Assembly With Stacked Corner Dummy Dies
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Solution Overview
Problem
Conventional Chip-on-Wafer-on-Substrate (CoWoS) semiconductor package assemblies experience stress concentration at the corners during reliability testing, leading to reliability issues due to the use of block dummy dies that concentrate stress and have high stiffness.
Innovation Solution
The semiconductor package assembly incorporates a dummy die structure composed of thin, stacked dummy dies in the corner region of the interposer, separated by adhesive layers, which reduces stress concentration by increasing the coefficient of thermal expansion and lowering stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If block dummy dies are used in the corner region, then the structural support is improved, but stress concentration occurs at the corners during reliability testing
Solution Approach 1:
The dummy die structure is divided into multiple thin dummy dies stacked in the first direction, with adhesive layers between them. This segmentation reduces stress concentration at the corner while maintaining structural support, as the stacked configuration distributes mechanical stress more evenly compared to a single block dummy die.
Solution Approach 2:
The dummy dies are designed with reduced thickness compared to conventional block dummy dies, and multiple adhesive layers are introduced between the thin dummy dies. This parameter change modifies the mechanical properties (lower stiffness, increased flexibility) to reduce stress concentration while maintaining adequate structural support.
2Reliability
If thin stacked dummy dies with adhesive layers are used, then stress distribution is improved, but the structural stiffness is reduced
Solution Approach 1:
The dummy die structure is segmented into multiple thin layers stacked vertically, which improves stress distribution across the corner region. The segmentation allows each thin layer to flex independently, distributing stress more evenly while the stack as a whole maintains adequate structural support.
Solution Approach 2:
The dummy die structure combines multiple materials: thin dummy die layers and adhesive layers. This composite structure achieves a balance between stress distribution (improved by the thin, flexible layers) and structural stiffness (maintained by the stacked configuration and adhesive bonding between layers).
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 design mitigates stress and reliability issues by distributing stress more evenly across the package, enhancing the overall reliability of the semiconductor package assembly.
Implementation Method 1
The dummy die structure includes dummy dies stacked on each other in a first direction, with adhesive layers between the dummy dies
Data Source
AI summary
A semiconductor package assembly is provided. The semiconductor package assembly includes a substrate, an interposer, a first die, a second die, and a dummy die structure. The interposer is disposed on the substrate. The interposer includes a central region and a peripheral region. The peripheral region includes a corner region and a non-corner region. The first die is disposed on the interposer in the central region. The second die is disposed beside the first die and is located in the non-corner region of the peripheral region of the interposer. The dummy die structure is disposed beside the first die and the second die and is located in the corner region of the peripheral region of the interposer. The dummy die structure includes dummy dies stacked on each other in a first direction.