Magnetic Force Transient Liquid-Phase Bonding for Metal Materials
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Solution Overview
Problem
Conventional transient liquid-phase bonding methods for metal materials are slow, prone to forming Kirkendall voids and layered structures, which reduce bonding strength, especially when applied to high-temperature applications like SiC chips in electric vehicles and aerospace, where high temperature soldering and Ag sintering are expensive and inefficient.
Innovation Solution
Applying a magnetic force to accelerate diffusion between ferromagnetic and diamagnetic or paramagnetic base metals using a low-melting-point metal powder paste, reducing bonding time and suppressing void formation by controlling magnetic interactions during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transient liquid-phase bonding method is used, then bonding is achieved through diffusion, but bonding time is long and Kirkendall voids and layered structures are formed
Solution Approach 1:
The patent replaces the conventional thermal diffusion mechanism with a magnetic field-driven mechanism. By applying a magnetic field during the transient liquid-phase bonding process, the diffusion of atoms is accelerated through magnetic force acting on ferromagnetic particles in the bonding interface, significantly reducing bonding time while preventing void formation.
Solution Approach 2:
The patent introduces magnetic field strength as a new controllable parameter to regulate the diffusion process. By adjusting the magnetic field intensity and duration, the bonding process can be optimized to achieve rapid diffusion without forming Kirkendall voids or layered structures, resolving the time-strength contradiction.
2Productivity
If temperature is increased to accelerate diffusion, then bonding time is reduced, but warpage or deterioration of the module occurs
Solution Approach 1:
The patent substitutes thermal energy with magnetic energy to drive diffusion. Instead of increasing temperature to accelerate atomic diffusion, a magnetic field is applied to exert force on ferromagnetic particles, achieving rapid bonding at lower temperatures and preventing module warpage and deterioration.
3Temperature
If high temperature soldering or Ag sintering is used for high temperature applications, then heat resistance is achieved, but cost increases
Solution Approach 1:
The patent employs a composite bonding approach using ferromagnetic particles embedded in a low-melting-point metal matrix. This composite structure enables the bonding interface to achieve high-temperature stability through the ferromagnetic component while the low-melting-point metal provides effective bonding, avoiding the need for expensive high-temperature materials like Au or Ag.
4Adaptability or versatility
If conventional transient liquid-phase bonding is applied to dissimilar materials, then bonding is achieved, but layered structure is formed creating weakness
Solution Approach 1:
The patent replaces thermal diffusion with magnetic field-driven diffusion to bond dissimilar materials. The magnetic field acts on ferromagnetic particles at the interface, promoting uniform mixing and preventing the formation of layered structures that would create weak planes, thereby enhancing joint strength while maintaining versatility.
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 method significantly shortens bonding time, reduces Kirkendall voids and layered structures, enhancing bonding reliability and strength, making it suitable for high-temperature applications like SiC chip bonding in electric vehicles and aerospace components.
Implementation Method 1
a magnetic force is applied to a transient liquid-phase bonding process, thereby shortening a transient liquid-phase bonding time
Implementation Method 2
forms an intermetallic compound via diffusion
Implementation Method 3
mixing a low melting point metal powder having a lower melting point than melting points of the first and second base metals
Data Source
AI summary
Disclosed is a method for transient liquid-phase bonding between metal materials using a magnetic force. In particular, in the method, a magnetic force is applied to a transient liquid-phase bonding process, thereby shortening a transient liquid-phase bonding time between the metal materials, and obtaining high bonding strength. To this end, an attractive magnetic force is applied to a ferromagnetic base while a repulsive magnetic force is applied to a diamagnetic base, thereby to accelerate diffusion. This may reduce a bonding time during a transient liquid-phase bonding process between two bases and suppress formation of Kirkendall voids and voids and suppress a layered structure of an intermetallic compound, thereby to increase a bonding strength.