Redistribution Structure Dummy Bump Layout for CTE-Strain Reliability
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Solution Overview
Problem
The mismatch in coefficient of thermal expansion (CTE) between substrate and semiconductor components in chip packages leads to deformation, strain concentration, and potential breaks in electrical connections, causing irreversible damage.
Innovation Solution
A dummy bump region (DBR) is introduced within the redistribution structure, comprising enhanced vias and wiring interconnects electrically isolated from semiconductor dies, acting as a stiffener to reduce deformation and strain caused by CTE mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional redistribution structure without dummy bump region is used, then device complexity is reduced, but reliability deteriorates due to strain concentration and deformation from CTE mismatch
Solution Approach 1:
The patent creates a dummy bump region that copies the structural characteristics of functional bump regions, including redistribution via layers and wiring interconnect layers. This copied structure acts as a mechanical stiffener without requiring electrical functionality, thereby improving reliability against CTE-induced deformation while maintaining manageable complexity through pattern replication rather than fundamental design changes
Solution Approach 2:
The dummy bump region serves as an intermediary structural element between the substrate and semiconductor die. It mediates the mechanical stress and deformation caused by CTE mismatch, absorbing and distributing strain away from the functional electrical connections. This intermediary structure protects the actual electrical pathways without requiring modification to the core electrical design
2Stability of the object's composition
If redistribution structure is made more rigid to resist deformation, then reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating dummy bump regions with specific structural characteristics (enhanced via layers and wiring interconnects) only in strategic locations where mechanical support is needed. The dummy bumps are positioned in non-functional areas between actual semiconductor dies, providing localized stiffening without requiring high-precision alignment with active electrical components. This localized approach reduces overall manufacturing precision requirements compared to making the entire redistribution structure uniformly rigid
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 DBR enhances the reliability of chip packages by suppressing deformation and reducing strain, preventing breaks in electrical connections and improving overall package reliability.
Implementation Method 1
a difference in coefficient of thermal expansion (CTE) values between the substrate and various adjoined or proximate components and layers may induce deformation (warpage) within the chip package
Data Source
AI summary
Methods and devices include a chip package structure, including a first semiconductor die, a second semiconductor die, a redistribution structure, and a first underfill material portion located between the redistribution structure and the first semiconductor die and the second semiconductor die. The redistribution structure includes a first redistribution structure portion physically and electrically connected to the first semiconductor die, a second redistribution structure portion physically and electrically connected to the second semiconductor die, and a dummy bump region positioned between and electrically isolated from the first redistribution structure portion and the second redistribution structure portion.