Pressure-Free Silver Sintering Assembly for Dense Fatigue-Resistant Joints
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Solution Overview
Problem
Existing methods for assembling electronic components, such as sintered metal connections, face challenges with low fatigue resistance due to porosity and difficulty in applying pressure to delicate components, leading to issues with thermomechanical stress and industrial scalability.
Innovation Solution
A pressure-free metal sintering process involving a sintering material with at least 80% metal particles of specific dimensions, undergoing pre-sintering and densification stages at controlled temperatures to achieve a densified joint without external force, allowing for assembly of fragile components and improved thermomechanical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure sintering is used to reduce porosity and improve fatigue resistance, then the joint density and thermomechanical resistance are improved, but delicate and fragile components cannot be assembled and the process becomes difficult to industrialize
Solution Approach 1:
The patent replaces the mechanical pressure application system with a thermal field system. Instead of using external pressure to achieve densification, the invention uses controlled thermal treatment (heating to specific temperatures followed by cooling) to induce sintering and densification of the metal powder joint. This substitution allows fragile components to be assembled without mechanical stress while still achieving the desired joint density and fatigue resistance through thermal activation of the sintering process.
2Reliability
If pressure sintering is applied to achieve densification, then void reduction and fatigue resistance are improved, but the assembly size is reduced and the process is difficult to scale industrially
Solution Approach 1:
The patent replaces the mechanical pressure application system with a thermal field system. Instead of using external pressure to achieve densification, the invention uses controlled thermal treatment (heating to specific temperatures followed by cooling) to induce sintering and densification of the metal powder joint. This substitution allows fragile components to be assembled without mechanical stress while still achieving the desired joint density and fatigue resistance through thermal activation of the sintering process.
Solution Approach 2:
The patent changes the controlling parameter from mechanical pressure to thermal parameters (temperature and time). By defining specific temperature ranges and heating/cooling rates, the process achieves consistent densification results that are easier to control and scale industrially compared to pressure application. The thermal parameters can be uniformly applied across large assemblies without the complexity of distributing mechanical pressure evenly.
3Ease of manufacture
If conventional pressureless sintering is used, then the assembly process is simpler, but the joints are low-density and porous with low fatigue resistance
Solution Approach 1:
The patent employs a periodic thermal action consisting of distinct heating and cooling phases. The assembly is heated to a specific temperature range to activate sintering and densification, then cooled at a controlled rate to achieve the desired microstructure and joint properties. This periodic thermal treatment, repeated in a controlled cycle, transforms the simple pressureless sintering into a process that produces high-density, low-porosity joints with improved fatigue resistance while maintaining process simplicity.
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 process results in hermetic assemblies with enhanced resistance to thermomechanical fatigue, facilitating easier and faster industrial implementation compared to pressure sintering, while reducing porosity and stress concentrations.
Implementation Method 1
a first time of more than five minutes at a first temperature above 200°C and strictly below the activation temperature of diffusion at grain boundaries; c) a densification step during which the assembly is heated for a second time at a second temperature above or equal to the activation temperature of diffusion at grain boundaries
Data Source
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AI summary
The invention relates to a method for assembly of a first element (10) with a second element (20) by metal sintering without pressure, the method comprising the following steps: a) a preparation step (40) during which a sintering material (51) is disposed at a boundary interface (30; 31) of the elements (10; 20); b ) a pre-sintering step (41) during which the assembly (52) is heated for a first period greater than five minutes to a first temperature greater than 200 °C and strictly less than or equal to the temperature for activating diffusion at the grain boundaries; c) a step of densification (42) during which the assembly (52) is heated to a second temperature greater than or equal to the temperature for activating diffusion at the grain boundaries.