Silver Sinter Paste with Auxiliary Particles for Gap Control
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Solution Overview
Problem
The existing silver sintering process for producing sintered connections faces challenges with high process pressure, organic content leading to pore formation, and limited precision in setting gap size between joining partners, which affects thermal conductivity and mechanical stability, especially in high-temperature applications.
Innovation Solution
Incorporating auxiliary particles with a larger grain size than structural particles into the sintering material or directly into the joining area to set a minimum gap width, reducing organic content and preventing excessive pressing of joining partners, thereby minimizing pore formation and ensuring precise gap control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high process pressure is applied in the sintering process, then the sintered connection achieves sufficient mechanical strength and thermal conductivity, but the joining force is limited and the sinter paste can be squeezed out laterally
Solution Approach 1:
The patent applies a encapsulation layer (flexible shell) around the sinter paste to contain it during isostatic pressurization. This prevents lateral squeezing out while allowing uniform pressure distribution, resolving the contradiction between achieving sufficient pressing force and maintaining processability.
Solution Approach 2:
The patent changes the pressure application mode from uniaxial to isostatic pressing, and adjusts the heating rate and holding time parameters. This allows achieving sufficient mechanical strength with controlled pressure that prevents paste extrusion, resolving the contradiction between strength and ease of operation.
2Ease of manufacture
If a high proportion of organic components is present in the sinter paste, then the viscosity and applicability of the paste are ensured, but large gas bubbles form during sintering, creating pores in the sintered layer
Solution Approach 1:
The patent extracts and removes organic components from the sinter paste through controlled heating and holding processes. This eliminates the source of gas bubbles that cause pores, while maintaining sufficient paste viscosity for application before sintering.
Solution Approach 2:
The patent performs preliminary heating and holding steps before final sintering to gradually remove organic components. This preliminary action prevents sudden gas bubble formation during main sintering, ensuring precise gap size control without sacrificing paste applicability.
3Stress or pressure
If very small structural particles including nanometer-range particles are used, then the increased surface energy provides driving force for sintering at reduced pressure, but the proportion of organic components increases while metal content decreases
Solution Approach 1:
The patent changes the particle size distribution parameter, using a mixture of fine and coarse particles instead of only nanometer-range particles. This maintains sufficient surface energy for low-pressure sintering while increasing the metal content proportion by reducing the relative amount of organic binder needed.
Solution Approach 2:
The patent creates a composite particle structure combining fine metallic particles for sintering activity and coarse metallic particles for structural integrity and metal content. This composite approach reduces organic content while maintaining low process pressure capability.
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 approach allows for precise setting of gap size, reduces pore content, enhances thermal conductivity, and maintains mechanical stability at high temperatures, overcoming service life limitations and improving heat transfer properties.
Implementation Method 1
a sintering process using sintered material in which at least two joining partners are sintered together to form a sintered layer
Implementation Method 2
a high process pressure that has to be applied in a sintering process
Implementation Method 3
an increasing proportion of organics has to be evaporated or burned
Implementation Method 4
an increasing proportion of organics has to be evaporated or burned
Implementation Method 5
The grain size of the auxiliary particles exceeds the grain size of the structure particles many times over. A minimum distance between the joining partners can be specified by selecting the grain size and the proportion of auxiliary particles
Implementation Method 6
the sintered layer has to ensure heat dissipation via thermal conductivity
Data Source
Figure 1~3
Figure 4~6
Figure 7
AI summary
The invention relates to a sintered material comprising metallic structure particles provided with an organic coating. It is envisaged in accordance with the invention that metallic and/or ceramic auxiliary particles (7) with a non-organic coating, which do not outgas in the course of the sintering process, are provided. The invention further relates to a sintered bond (1) and to a process for producing a sintered bond (1).