Silver Paste Composition for Direct Bonding on Oxidized Copper
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Solution Overview
Problem
Existing silver pastes struggle to bond electronic components directly to copper or copper alloy members without a metallized layer, resulting in low bonding strength.
Innovation Solution
A silver paste comprising silver powder, fatty acid silver salt, aliphatic amine, high-dielectric-constant alcohol, and a solvent with specific dielectric constants, which forms a bonding layer directly on the copper or copper alloy member by reacting with the oxide film and promoting sinterability of silver nanoparticles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional silver paste is used without a metallized layer, then the process complexity is reduced, but the bonding strength deteriorates
Solution Approach 1:
The silver paste is formulated with reactive components (fatty acid silver salt and aliphatic amine) that perform preliminary chemical action on the copper surface oxide film during the bonding process itself, eliminating the need for preliminary metallized layer formation while ensuring strong bonding
Solution Approach 2:
The invention changes the chemical composition parameters of the silver paste by incorporating specific ratios of fatty acid silver salt (0.1-10 wt%) and aliphatic amine (0.1-10 wt%), which alter the paste's reactivity toward copper oxide, enabling direct bonding without metallized layers
2Ease of manufacture
If silver paste is applied directly on copper surface with oxide film, then the manufacturing process is simplified, but the bonding reliability deteriorates
Solution Approach 1:
The invention converts the harmful oxide film on the copper surface into a beneficial intermediate layer by using fatty acid silver salt and aliphatic amine to react with and transform the oxide, improving bonding reliability while maintaining process simplicity
Solution Approach 2:
The fatty acid silver salt and aliphatic amine act as intermediary substances that mediate between the silver paste and the copper oxide surface, enabling reliable bonding directly on the oxidized copper surface without requiring additional metallized layers
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 silver paste achieves high-strength bonding of electronic components to copper or copper alloy members by removing oxide films and enhancing sinterability, even without a metallized layer.
Implementation Method 1
the high-dielectric-constant alcohol having a dielectric constant of 34 or more and 44 or less reacts with an oxide film present on the surface of the copper or copper alloy member upon heating, and due to that reducing action, an oxide film of CuO and the like is removed from the surface
Implementation Method 2
When the silver paste layer formed by this silver paste is heated, a reduction reaction of the complex occurs more smoothly by this high-dielectric-constant alcohol. When the silver in the complex is reduced, silver nanoparticles are formed, and these silver nanoparticles enhance the sinterability of the silver powder
Data Source
AI summary
This silver paste is used to form a silver paste layer by applying the silver paste directly on the surface of a copper or copper alloy member, and the silver paste includes a silver powder, a fatty acid silver salt, an aliphatic amine, a high-dielectric-constant alcohol having a dielectric constant of 30 or more, and a solvent having a dielectric constant of less than 30. The content of the high-dielectric-constant alcohol is preferably 0.01% by mass to 5% by mass when an amount of the silver paste is taken as 100% by mass.