Undercoolled Core-Shell Metal Particles for Ambient Joining
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Solution Overview
Problem
Current joining and repair techniques face challenges in miniaturization, efficiency, cost, and environmental concerns, particularly at the microscale, and require high processing temperatures, making them unsuitable for large-scale manufacturing and complex structure fabrication.
Innovation Solution
The use of undercooled metallic core-shell particles with a stable liquid metallic core encapsulated in an oxide or organic shell, which can be ruptured to form a metallurgical bond at ambient conditions, allowing for low-temperature joining and repair without the need for heating or specialized equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional joining techniques like soldering and welding are used, then strong metallurgical bonds can be formed, but high processing temperatures and specialized equipment are required
Solution Approach 1:
The invention changes the temperature parameter from high (conventional soldering/welding) to ambient conditions by using undercooled liquid metal particles. The particles are prepared in an undercooled state below their melting point, allowing them to remain liquid at ambient temperature and form bonds without external heating
Solution Approach 2:
The invention utilizes phase transition of metal particles from solid to liquid state through undercooling. The particles are cooled below their melting point to create a metastable liquid state, which then transitions to solid upon contact with substrates, forming strong metallurgical bonds at ambient temperature
2Object-affected harmful factors
If lead-free solders are used to address environmental concerns, then environmental safety is improved, but processing temperatures increase above 450 K
Solution Approach 1:
The invention changes the temperature parameter from high (>450 K for lead-free solders) to ambient conditions by using undercooled liquid metal particles. This allows the use of environmentally safe materials without the penalty of high processing temperatures
Solution Approach 2:
The invention uses consumable liquid metal particles that are applied and then consumed in the joining process. The particles serve their purpose by forming bonds and are depleted, similar to disposable materials, eliminating the need for repeated high-temperature processing
3Manufacturing precision
If nanotechnology and in situ manipulation techniques are used for joining, then precision at microscale is improved, but efficiency decreases and costs increase
Solution Approach 1:
The undercooled liquid metal particles self-assemble and self-bond when brought into contact with substrates. The particles naturally flow and form metallurgical bonds without requiring external manipulation, directing assembly, or complex in situ processing, thereby improving efficiency
Solution Approach 2:
The invention divides the joining process into discrete particle applications. Individual undercooled liquid metal particles are applied to specific locations, each independently forming a bond. This segmented approach enables precise microscale joining while maintaining high throughput through parallel processing
4Temperature
If undercooled metal particles are used for joining, then processing temperature is reduced to ambient conditions, but particle stability against solidification becomes challenging
Solution Approach 1:
The invention applies preliminary protective coating to the undercooled liquid metal particles before use. The coating prevents premature solidification and contamination, maintaining particle stability during storage and handling. This preliminary protection enables the particles to remain in the metastable liquid state until application
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 enables efficient, low-cost joining and repair of metallic components at ambient temperatures, reducing energy consumption and eliminating the need for high-tech instrumentation, while maintaining stability and homogeneity of the undercooled liquid metallic core.
Implementation Method 1
Undercooling of metals (i.e. cooling of a liquid metal or alloy below its freezing point without it becoming solid, also known as 'supercooling') has been widely studied
Implementation Method 2
Due to the metastable nature of undercooled metals, their production in good yields is an experimental challenge
Implementation Method 3
the outer shells of the undercooled core-shell particles is ruptured to release the undercooled liquid metallic material of the cores to contact the components and solidify to produce a metallurgical joint between the components
Implementation Method 4
release the undercooled liquid metallic material of the cores to contact the components and solidify to produce a metallurgical joint
Data Source
AI summary
Undercooled liquid metallic core-shell particles, whose core is stable against solidification at ambient conditions, i.e. under near ambient temperature and pressure conditions, are used to join or repair metallic non-particulate components. The undercooled-shell particles in the form of nano-size or micro-size particles comprise an undercooled stable liquid metallic core encapsulated inside an outer shell, which can comprise an oxide or other stabilizer shell typically formed in-situ on the undercooled liquid metallic core. The shell is ruptured to release the liquid phase core material to join or repair a component(s).