Corrosion-Protective Copper Paste for Dipole Tag Antennas

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Solution Overview

Problem

Copper paste is prone to oxidation, leading to a rapid decrease in conductivity, and conventional methods struggle with uniform dispersion and heat resistance, making it unsuitable for long-term electronic applications without additional corrosion protection and complex patterning processes.

Innovation Solution

A method involving a hydrochloric acid and phosphoric acid treatment of copper powder, followed by the application of a vinyl imidazole-silane copolymer and poly(4-styrenesulfonate) to form a corrosion-protective coating layer, combined with centrifugation and screen printing to create a copper paste with enhanced dispersability and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If copper paste is used as an alternative to silver paste, then cost is reduced, but conductivity stability deteriorates due to oxidation

Engineering Contradiction:

Improveconductivity stabilityVSAvoidoxidation susceptibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an imidazole-based corrosion-protective agent as an intermediary substance that forms a protective coating layer on the copper powder surface. This coating layer acts as a barrier between the copper and oxidizing environments (air and binder resin), preventing direct contact and oxidation reactions, thereby maintaining conductivity stability over time

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite structure by combining copper powder with an imidazole-based corrosion-protective coating layer. This composite material integrates the high conductivity of copper with the oxidation-resistant properties of the imidazole coating, achieving both cost-effectiveness and long-term conductivity stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional copper paste composition is used, then manufacturing is simpler, but dispersion uniformity deteriorates leading to corrosion

Engineering Contradiction:

Improvecorrosion resistanceVSAvoiddispersion uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The imidazole-based corrosion-protective agent serves as an intermediary that improves the interfacial compatibility between copper powder particles and the binder resin. This coating facilitates more uniform dispersion during mixing while simultaneously providing corrosion protection, resolving the trade-off between manufacturing simplicity and dispersion uniformity

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If imidazole compound is used for corrosion protection, then oxidation is prevented, but thermal history occurs at 150°C or more

Engineering Contradiction:

Improveoxidation preventionVSAvoidheat resistance

Core Design Contradiction:

Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent modifies the chemical structure of the imidazole compound by introducing aromatic substituents (such as phenyl, naphthyl, or heterocyclic groups). This structural modification increases the thermal stability of the imidazole ring system, allowing the coating to maintain its protective function at elevated temperatures (up to 150°C and above) without decomposing or losing effectiveness

Inventive Principle:

Principle #35Parameter changes

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 results in copper paste with improved heat resistance, uniform conductivity, and flexibility, enabling cost-effective mass production of copper paste thin films suitable for dipole tag antennas with high efficiency and adaptability.

Implementation Method 1

introducing a hydrochloric acid aqueous solution to copper powder to etch the surface thereof

Methodology Applied

Scientific EffectAcid etching: Oxidation

Implementation Method 2

introducing a phosphoric acid aqueous solution to form a corrosion-protective coating layer on the surface of copper powder

Methodology Applied

Scientific EffectChemical deposition: Deposition (physical)

Implementation Method 3

introducing a phosphoric acid aqueous solution, a vinyl imidazole-silane copolymer, and poly(4-styrenesulfonate) to form a corrosion-protective coating layer on the surface of copper powder

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 4

using a centrifuging method

Methodology Applied

Scientific EffectCentrifugal separation: Centrifugal Separation

Data Source

PatentUS9945038B2Preparation of corrosion-protective copper paste through single process and application thereof to dipole tag antenna

Publication Date: 2018.04.17 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

AI summary

Provided are a method of producing corrosion-protective copper paste through a single process and an application thereof to a dipole tag antenna. Copper powder is surface-etched by using a hydrochloric acid in an inert gas atmosphere, a phosphoric acid aqueous solution is added thereto to form copper phosphate on the etched surface of the copper powder, and then, a vinyl imidazole-silane copolymer and poly(4-styrenesulfonate) were introduced thereto to form a corrosion-protective coating layer on the surface of copper powder on which the copper phosphate has been formed, and a centrifuge and an agate mortar are used to prepare a copper paste having high viscosity and high dispersability. When a copper paste thin film is formed on a flexible film by screen printing, a produced dipole tag antenna may have high efficiency.