Convex-Concave Bump Structure for Solder Joint Reliability
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Solution Overview
Problem
Conventional bump structures with flat surfaces in semiconductor packaging face issues such as solder bridge formation, cold joints, bump cracks, and electromigration failures, which affect yield and reliability.
Innovation Solution
The proposed bump structure features a convex projection on one bump and a corresponding concave recess on the opposing bump, with layers of solder covering these non-flat surfaces, allowing for improved solder joint formation and increased cohesive force, reducing the risk of solder crack propagation and electromigration failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flat bump surfaces are used in conventional semiconductor packaging, then the manufacturing process is simple, but solder bridge formation, cold joints, bump cracks, and electromigration failures occur affecting yield and reliability
Solution Approach 1:
The patent applies curvature by replacing flat bump surfaces with non-flat surfaces featuring convex projections and concave recesses. The convex projection on one bump mates with the concave recess on the opposing bump, creating a curved interface that improves solder joint reliability by preventing solder bridge formation and reducing stress concentration, thereby resolving the technical contradiction between reliability improvement and structural complexity.
Solution Approach 2:
The patent implements asymmetry by creating non-symmetric bump structures where one bump has a convex projection and the opposing bump has a corresponding concave recess. This asymmetric design prevents solder bridge formation between adjacent bumps while improving cohesive force, addressing the reliability issue without requiring complete symmetry across all bumps, thus managing device complexity.
2Manufacturing precision
If non-flat bump surfaces with convex projections and concave recesses are used, then solder joint reliability and electromigration performance improve, but manufacturing complexity increases
Solution Approach 1:
The curved surfaces with convex projections and concave recesses provide precise alignment and positioning for solder joints, improving manufacturing precision by reducing misalignment and enhancing solder flow control during the reflow process, while the curvature itself is achieved through standard semiconductor manufacturing techniques.
Solution Approach 2:
The patent applies local quality by creating specific convex projections and concave recesses only at critical locations on the bump surfaces where solder joint precision is most needed, rather than making the entire bump structure complex. This localized approach improves solder joint precision while minimizing overall device complexity.
3Ease of manufacture
If conventional flat bump structures are used, then device complexity is low, but solder crack propagation and electromigration failures occur
Solution Approach 1:
The non-flat surfaces with convex and concave features redistribute mechanical stress away from concentrated points, reducing the likelihood of solder crack propagation. The curved interface also improves electromigration resistance by enhancing solder joint integrity, achieving improved reliability while maintaining ease of manufacture through standard semiconductor fabrication processes.
Solution Approach 2:
The convex projection and concave recess structure acts as a preemptive measure against solder crack propagation and electromigration failures. By designing the bump structure with these features beforehand, the patent creates inherent resistance to these failure modes before they can occur during device operation, thereby improving reliability without complicating the manufacturing process.
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 enhances yield, reliability, and electromigration performance by providing better solder volume control, reducing bridge risks, and improving pull/shear stress resistivity, while preventing solder crack propagation and electromigration failures.
Implementation Method 1
the top package may be interconnected to the bottom package by reflowing a solder paste disposed on opposing copper bumps to form an electrical connection between the packages
Data Source
AI summary
A bump structure for electrically coupling semiconductor components is provided. The bump structure includes a first bump on a first semiconductor component and a second bump on a second semiconductor component. The first bump has a first non-flat portion (e.g., a convex projection) and the second bump has a second non-flat portion (e.g., a concave recess). The bump structure also includes a solder joint formed between the first and second non-flat portions to electrically couple the semiconductor components.