Intermetallic Compound Shell Metal Particles for Kirkendall Void Suppression
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Solution Overview
Problem
Conventional bonding materials fail to maintain high bonding strength over time in high-temperature devices and are prone to Kirkendall void formation, which reduces mechanical strength and reliability in stacked semiconductor substrates and three-dimensional structures.
Innovation Solution
A metal particle with a nanometer-sized intermetallic compound outer shell, composed of metals like Cu, Al, and Sn, that suppresses Kirkendall void formation by controlling diffusion rates and enhancing heat resistance through a combination of low- and high-melting-point components, used in electro-conductive pastes and formed articles for interconnects and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding materials are used in high-temperature devices, then initial bonding strength can be achieved, but bonding strength deteriorates over time and Kirkendall voids form
Solution Approach 1:
The patent employs composite material structures including intermetallic compound particles (such as Cu6Sn5, Cu3Sn) dispersed in metal matrixes (Sn, Cu, or alloys), creating a multi-phase composite that combines the low melting point and ductility of Sn with the high strength and heat resistance of intermetallic compounds, thereby maintaining bonding strength over extended service durations in high-temperature environments
Solution Approach 2:
The patent controls particle size parameters (intermetallic compound particles: 0.1-10 μm, metal particles: 1-20 μm) and compositional parameters (weight ratios of Sn, Cu, and intermetallic compounds) to optimize both initial bonding strength and long-term stability, with specific compositional ranges (e.g., Sn: 70-95 wt%, Cu: 5-30 wt%) designed to suppress Kirkendall void formation while maintaining solderability and bonding performance
2Reliability
If metal particles are used to form interconnects, then electrical conductivity is achieved, but Kirkendall voids reduce mechanical strength
Solution Approach 1:
The patent introduces intermetallic compound particles as intermediary phases between dissimilar metals (such as Cu and Sn), which mediate the diffusion process and provide nucleation sites that prevent vacancy accumulation, thereby suppressing Kirkendall void formation while maintaining electrical conductivity through the continuous metal matrix phase
Solution Approach 2:
The patent creates local compositional variations by dispersing intermetallic compound particles throughout the metal matrix, providing localized regions with controlled diffusion characteristics that prevent Kirkendall void formation at critical interfaces while maintaining overall mechanical strength and electrical conductivity of the interconnect structure
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 solution provides highly reliable, high-quality electric interconnects and bonding portions with improved heat resistance and mechanical strength, reducing the likelihood of Kirkendall voids and maintaining performance across varying temperatures.
Implementation Method 1
suppresses Kirkendall void formation by controlling diffusion rates
Implementation Method 2
enhancing heat resistance through a combination of low- and high-melting-point components
Data Source
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AI summary
Aiming at providing a metal particle, an electro-conductive paste, a formed article, and a laminated article that are able to form a highly reliable and high-quality electric interconnect, an electro-conductive bonding portion, or a three-dimensional structure that is less likely to produce the Kirkendall void, this invention discloses a metal particle which include an outer shell and a core part, the outer shell including an intermetallic compound and covering the core part.