Surface-Treated Copper Powder for Oxidation-Resistant Conductive Paste
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Solution Overview
Problem
Existing electroconductive copper pastes face issues with oxidation of copper powders, leading to increased volume resistivity and reduced reliability, especially when exposed to high humidity and temperature, despite the use of reducing agents like ascorbic acid, which do not sufficiently suppress oxidation.
Innovation Solution
The use of surface-treated copper powders with adhered ascorbic acid or its derivatives, combined with a binder resin and an acidic group-containing dispersant, to form an electroconductive composition that maintains good conductivity even when fired in air, by reducing copper oxide and promoting intimate contact between copper powders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper powder is used in electroconductive paste, then ion migration resistance is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent introduces ascorbic acid as an intermediary substance that mediates between copper powder and oxygen/water. The ascorbic acid molecules adhere to the copper powder surface and act as a protective barrier, preventing direct contact between copper and oxidizing agents while maintaining the copper's electroconductive properties
Solution Approach 2:
The patent creates a composite structure where ascorbic acid forms a coating layer on the copper powder surface. This composite material combines the high electroconductiveivity of copper with the oxidation resistance of ascorbic acid, achieving both ion migration resistance and oxidation resistance simultaneously
2Stability of the object's composition
If reducing agents are added to copper paste, then oxidation resistance is improved, but volume resistivity increases
Solution Approach 1:
The patent applies ascorbic acid locally on the copper powder surface rather than uniformly throughout the paste. This localized treatment provides oxidation protection exactly where needed (at the copper surface) while minimizing the amount of reducing agent in the bulk material, thus maintaining low volume resistivity
3Ease of manufacture
If copper powder is exposed to humid environment, then processing ease is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent performs preliminary action by pre-coating the copper powder with ascorbic acid before the copper powder is exposed to humid processing environments. This advance protection ensures that when the copper paste undergoes humid heat treatment, the copper powder is already protected and cannot oxidize, maintaining both processing ease and oxidation resistance
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 results in an electroconductive film with improved electroconductivity and wet-heat resistance, effectively preventing oxidation and maintaining reliability in harsh environments.
Implementation Method 1
a surface-treated copper powder (AB) in which ascorbic acid or a derivative thereof (B) is adhered to the surface of a copper powder (A)... reduce copper oxide and promoting intimate contact between copper powders
Implementation Method 2
an electroconductive film which is a dried material or a cured material of an electroconductive composition prepared by heating at a temperature of 120 to 190°C for 10 to 90 minutes
Data Source
Figure 1~2
AI summary
The present invention addresses the problem of providing an electroconductive composition which, even when burned in the air, can form an electroconductive film that exhibits satisfactory electroconductivity and moist-heat resistance. The problem is solved with an electroconductive composition which comprises: a surface-treated copper powder (AB) comprising a copper powder (A) and an ascorbic acid derivative (B) adherent to the surface thereof; a binder resin (C); and a dispersant (D) having an acidic group.