Silver-Copper Sintering Composition for Fluxless Copper Bonding
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Solution Overview
Problem
Existing silver sintering compositions face limitations in achieving stable adhesion and sintering strength on copper substrates, particularly in high power and high temperature applications, and often require fluxing agents that leave residues, necessitating a cleaning step.
Innovation Solution
A silver sintering composition comprising 80-96% silver filler, 0.01-10% copper alloy with 60-90% copper content, and 2-10% matrix components such as resin or solvent, which allows for stable sintering on copper, gold, or silver substrates without flux residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver sintering composition is used on copper substrates, then electrical and thermal conductivity is improved, but adhesion strength deteriorates due to lack of inter-metallic bonding
Solution Approach 1:
The patent uses a composite material system combining silver particles (for conductivity) with a copper-tin-aluminum alloy matrix (for adhesion). The alloy matrix forms inter-metallic bonds with copper substrates while the silver particles provide electrical and thermal conduction pathways, resolving the contradiction between conductivity and adhesion strength.
2Strength
If fluxing agents are used to achieve inter-metallic bonding, then adhesion strength is improved, but harmful residues are generated requiring cleaning steps
Solution Approach 1:
The patent extracts and eliminates the fluxing agent component from the sintering composition, replacing it with a fluxless copper-tin-aluminum alloy matrix that achieves inter-metallic bonding through direct metallurgical reaction during sintering, thereby avoiding harmful flux residues while maintaining adhesion strength.
3Strength
If resin is added to silver conductive composition for adhesion, then adhesion strength is improved, but thermal and electrical conductance deteriorates
Solution Approach 1:
The patent changes the material parameter from organic resin to inorganic copper-tin-aluminum alloy matrix, which maintains metallic conductivity while providing adhesion capability through inter-metallic bonding, thus improving adhesion strength without sacrificing thermal and electrical conductance.
4Reliability
If silver conductive composition is used without resin, then thermal and electrical conductance is improved, but adhesion strength deteriorates
Solution Approach 1:
The patent creates a composite material where copper-tin-aluminum alloy particles are combined with silver particles, forming a fluxless sintering composition that provides both metallic conductivity and adhesion strength through inter-metallic bonding with the substrate, eliminating the need for resin while maintaining conductance.
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 composition achieves improved adhesion and sintering strength on copper substrates, eliminating the need for fluxing agents and ensuring robust bonding at elevated temperatures.
Implementation Method 1
silver sintering composition containing a copper alloy for metal bonding... capable of stably sintering on various metal substrates such as copper, gold or silver, particularly copper with good adhesion and sintering strength
Implementation Method 2
silver sintering composition comprising 80-96% silver filler, 0.01-10% copper alloy with 60-90% copper content, and 2-10% matrix components... achieves improved adhesion and sintering strength on copper substrates
Data Source
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AI summary
A silver sintering composition containing a copper alloy is disclosed, which is capable of being stably sintered on various metal substrates such as copper, gold or silver with good adhesion and sintering strength.