Bonding Member With Intermetallic Compound For High Shear Strength
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Solution Overview
Problem
Existing bonding members either result in joint portions with low shear strength due to porous structures or form heterogeneous structures with slow intermetallic compound formation rates, leading to potential peeling and destruction from Kirkendall void growth.
Innovation Solution
A bonding member configuration with a first and second metal layer sandwiching a third metal layer containing dispersed particles, where the third metal layer forms an intermetallic compound with both layers, enhancing the reaction area and compactness, and using a flux to improve adhesion and reduce voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a paste-like bonding member containing low melting point metal and high melting point metal is heated to form an intermetallic compound, then the joint portion becomes porous with reduced material amount, but the shear strength decreases
Solution Approach 1:
The patent applies local quality by creating different regions within the bonding member: a first region with high melting point metal particles and intermetallic compound, and a second region with low melting point metal. This local differentiation allows the high melting point region to provide structural strength while the low melting point region fills voids to create density, resolving the contradiction between porosity and strength
Solution Approach 2:
The bonding member is designed as a composite material combining high melting point metal particles, intermetallic compound, and low melting point metal in specific proportions. This composite structure enables simultaneous achievement of density (through void filling) and shear strength (through the intermetallic compound framework and composite architecture)
2Manufacturing precision
If high melting point metal particles are bound in a plastic deformed state with metal foils, then a dense structure is achieved, but the intermetallic compound formation rate becomes slow due to limited contact area
Solution Approach 1:
The patent changes the physical state parameter of the low melting point metal from solid to liquid by heating, which dramatically increases its ability to fill voids and contact high melting point metal particles. This parameter change (melting) accelerates the intermetallic compound formation rate while maintaining the dense structure achieved through plastic deformation
3Length of moving object
If metal particles are caused to remain in a joint portion to increase minimum thickness, then stand-off height is secured, but the joint portion becomes heterogeneous with slow reaction rate
Solution Approach 1:
The patent uses local quality by designating specific regions for different functions: high melting point metal particles and intermetallic compound in the first region provide structural integrity and homogeneous composition, while low melting point metal in the second region ensures complete reaction and eliminates heterogeneity, while collectively maintaining adequate joint thickness
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 achieves a dense and homogeneous joint structure with increased shear strength, reduced peeling, and minimized Kirkendall void formation, ensuring a robust and uniform bond.
Implementation Method 1
the low melting point metal is melted to react with the high melting point metal and thus to form an intermetallic compound
Implementation Method 2
the particles of the third metal body have an average particle size (D90) of not less than 0.1 μm and not more than 45 μm, thereby a center portion of each of the particles can be transformed into the intermetallic compound
Implementation Method 3
minute Kirkendall voids are formed in the joint portion with the lapse of time due to a difference in rate of metal diffusion reaction between dissimilar metals
Data Source
AI summary
A bonding member having a container between a first foil and a second foil. The container includes metal particles having a melting point higher than a melting point of the first foil and a melting point of the second foil, a film material in which the metal particles are dispersed, and intermetallic compounds formed by a reaction between the first foil or the second foil and the metal particles. The first foil and the metal particles are bonded with the intermetallic compound interposed therebetween, and the second foil and the metal particles are bonded with the intermetallic compound interposed therebetween.