Reducing Solvent Composition for Conductive Copper Sintering
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Solution Overview
Problem
Existing bonding methods using copper sintered objects and electroconductive pastes face complications such as the need for immediate sintering and laborious surface treatment to prevent re-oxidation and corrosion, and generate voids leading to reduced bondability.
Innovation Solution
A solvent composition containing a reducing organic substance, a basic compound, and optionally a coordinating organic compound is applied to a metal member, dissolving the metal oxide film and precipitating metal nanoparticles, allowing for easy production of a sintered object with excellent electroconductivity and bondability without removing the solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper nanoparticles are sintered in a reducing atmosphere to prevent re-oxidation, then electroconductivity is improved, but the operation becomes complicated and requires immediate sintering
Solution Approach 1:
The patent applies a reducing agent (formic acid) to the copper nanoparticle aggregate before sintering, creating a protective reducing environment in advance. This preliminary action eliminates the need for immediate sintering in a reducing atmosphere, allowing the material to be stored and handled without re-oxidation concerns while maintaining electroconductivity.
Solution Approach 2:
The formic acid acts as an intermediary substance that mediates between the copper nanoparticles and oxygen. It provides a localized reducing environment at the particle surface, preventing oxidation without requiring the entire system to be in a reducing atmosphere, thus simplifying the sintering process.
2Reliability
If a reducing agent or etching solution is applied to remove surface oxide film, then electroconductivity is improved, but laborious removal efforts are required
Solution Approach 1:
The patent combines the reducing agent (formic acid) with the sintering process itself, merging the oxide removal function with the bonding process. This eliminates the need for separate, laborious oxide removal steps while still achieving the necessary surface preparation for high electroconductivity.
Solution Approach 2:
The formic acid applied to the copper nanoparticle aggregate performs multiple functions automatically: it acts as a reducing agent to prevent oxidation, serves as a dispersant to maintain particle separation, and provides the necessary surface treatment. The material essentially prepares itself for sintering without external intervention.
3Ease of operation
If formic acid decomposition gas is generated during sintering, then sintering can proceed without reducing atmosphere, but voids are generated reducing bondability
Solution Approach 1:
The patent extracts or removes the formic acid decomposition gas from the sintering zone by applying the formic acid to the copper nanoparticle aggregate rather than to a pre-formed compact. This allows the gas to escape during the granulation process before the material is pressed into a dense form, preventing void formation while maintaining the benefits of formic acid decomposition.
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 solvent composition enables sintering at lower temperatures with improved electroconductivity and bondability by suppressing oxidation and corrosion, eliminating the need for additional surface treatments.
Implementation Method 1
a sintered object having excellent electroconductivity and bondability can be easily obtained from such a solvent-treated metal member without removing the solvent after the treatment
Implementation Method 2
a metal oxide film on the surface of the metal member can be dissolved
Implementation Method 3
a coordinating organic substance is applied to a metal member, dissolving the metal oxide film and precipitating metal nanoparticles
Data Source
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AI summary
There is provided a solvent composition which does not need to be removed after application and allows a sintered object having excellent electroconductivity and bondability to be easily produced. The solvent composition of the present disclosure is a solvent composition for sintering aids, the solvent composition containing a reducing organic substance and a basic compound. The solvent composition of the present disclosure is also a solvent composition including a reducing organic substance, a basic compound, and a coordinating organic compound other than compounds included as the basic compound, and the coordinating organic compound has a higher boiling point than the reducing organic substance.