Composite Metal Particles for Low-Temperature Sintering
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Solution Overview
Problem
Existing metal pastes for bonding agents in element mounting require low-temperature sintering and high elongation, but current technologies, such as fine-silver-particles adhered silver powder and core-shell type metal microparticles, fail to achieve sufficient elongation and low-temperature sintering simultaneously.
Innovation Solution
Composite particles comprising microparticles with an average crystallite diameter of 0.6 to 10 μm and nanoparticles of the same metal type with an average diameter of 3 to 100 nm, adhered to the surface of the microparticles, allowing for low-temperature sintering and achieving a large extension in the sintered body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fine silver particles with small crystallite diameter are used to enable low-temperature sintering, then sintering temperature is reduced, but the sintered body exhibits insufficient extension
Solution Approach 1:
The invention segments the particle population into two distinct size classes: microparticles (0.6-10 μm) that provide structural integrity and elongation, and nanoparticles (3-100 nm) that facilitate low-temperature sintering. This segmentation allows each particle type to fulfill its specific function without compromising the other properties
Solution Approach 2:
The invention creates a composite particle system combining microparticles and nanoparticles of the same metal type. The microparticles form the bulk structure providing elongation, while the nanoparticles adhere to surfaces and enable low-temperature sintering through their high surface energy and reactivity
2Temperature
If core-shell type metal microparticles with different metal species are used, then low-temperature sintering is achieved, but the sintered body becomes fragile due to alloy formation
Solution Approach 1:
The invention uses homogeneous material composition where both microparticles and nanoparticles are made of the same metal type. This eliminates alloy formation and associated fragility while maintaining the low-temperature sintering capability provided by the nanoparticle component
3Temperature
If silver coated particles are used, then low-temperature sintering is attempted, but sufficient sintering does not occur at low temperature
Solution Approach 1:
The invention changes the critical parameter of particle size to achieve low-temperature sintering. By using nanoparticles with diameters of 3-100 nm instead of conventional coated particles, the high surface energy and reactivity of the nanoparticles enable complete and reliable sintering at low temperatures
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 composite particles enable sintering at temperatures as low as 300°C, resulting in a sintered body with a large crystallite diameter and sufficient elongation, making them suitable for bonding agents in element mounting.
Implementation Method 1
The nanoparticles are adhered to a surface of the microparticle
Implementation Method 2
the composite particles are sinterable at a low temperature, and allow forming a sintered body that exhibits a large extension
Data Source
AI summary
Composite particles sinterable at a low temperature and allow forming a sintered body that exhibits a large extension are provided. The composite particles include microparticles having an average crystallite diameter of 0.6 to 10 μm and containing a metal, and nanoparticles adhered to a surface of the microparticle, having an average crystallite diameter of 3 to 100 nm, and containing a metal of a same kind as the metal contained in the microparticle.