Metal Paste Sintering for Low-Stress Electronic Connections
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Solution Overview
Problem
The challenge in power and consumer electronics is connecting pressure- and temperature-sensitive components, such as LEDs or thin silicon chips, which requires methods that provide both high electrical and thermal conductivity while avoiding brittleness and internal mechanical tension, especially for large-surfaced components.
Innovation Solution
A sintering method using a metal paste with 75-90% copper or silver particles coated with organic compounds, 5-20% organic solvent, and 2-20% of different metal particles like molybdenum or nickel core-silver jacket particles, which are sintered between components to create stable, low-porosity connections without brittleness or internal tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive technology is used to connect pressure- and temperature-sensitive components, then the components can be connected without sintering, but the contact sites have insufficient heat conductivity and electrical conductivity
Solution Approach 1:
The invention changes the material parameters of the paste by incorporating specific metal particles (copper, silver, aluminum) with controlled size distributions (D10, D50, D90 values) and compositions. This enables the paste to achieve both adhesive properties for connection and high conductivity for heat and electricity transfer, resolving the contradiction between ease of manufacture and reliability.
2Reliability
If sintering technology is used to connect components, then stable connections with high conductivity are achieved, but the components are subjected to high pressure and temperature that may damage pressure- and temperature-sensitive components
Solution Approach 1:
The invention modifies the sintering process parameters by using a specially formulated paste with low melting point metal particles (aluminum, copper, silver) that enable sintering at reduced temperatures and pressures. The controlled particle size distribution and organic coating composition allow the paste to flow and bond at lower temperatures, reducing thermal and mechanical stress on sensitive components while maintaining connection stability and conductivity.
Solution Approach 2:
The invention uses a composite paste material containing multiple metal particles (copper, silver, aluminum) with different properties, organic compounds, and solvents. This composite formulation combines the high conductivity of noble metals with the low melting point and flowability of base metals, enabling effective sintering at reduced temperatures and pressures while achieving stable, conductive connections.
3Ease of manufacture
If conventional metal paste is used for sintering, then connections are formed, but the sintering layers become brittle and form internal mechanical tension after sustained temperature stress
Solution Approach 1:
The invention changes the compositional parameters of the metal paste by incorporating specific ratios of ductile metals (copper, silver, aluminum) and controlling particle size distributions. This composition enables the sintering layer to maintain ductility and resist brittleness even after sustained temperature stress, while still forming stable connections.
Solution Approach 2:
The invention applies local quality by having different metal particles serve different functions within the paste: copper and silver provide conductivity and structural integrity, while aluminum provides low-temperature flowability and bonding. The organic coating provides localized protection and control over particle behavior during sintering, resulting in a sintering layer with optimized local properties that resists brittleness and internal tension.
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 method produces connections with high electrical and thermal conductivity, maintaining strength even under sustained temperature stress, suitable for both pressure-sintering and pressure-less conditions, effectively addressing the issues of brittleness and mechanical tension in large-surfaced components.
Implementation Method 1
the components to be connected are often subjected to sintering. Sintering technology is a very simple method for connecting components in stable manner.
Implementation Method 2
75 to 90% by weight (percent by weight) of at least one metal that is present in the form of particles that comprise a coating that contains at least one organic compound
Data Source
AI summary
The invention relates to a metal paste, containing (A) 75 to 90% by weight of copper and/or silver particles that are provided with a coating containing at least one organic compound, (B) 5 to 20% by weight of an organic solvent, and (C) 2 to 20% by weight of at least one type of metal particles different from the particles of (A) and having an average particle size (d50) in the range of 0.2 to 10 μm. The metal particles of component (C) are selected from the group consisting of molybdenum particles and nickel core-silver shell particles with a silver content of 10 to 90% by weight.