Copper Nanoparticle Ink With CuH for Low-Temperature Air Sintering

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Solution Overview

Problem

Current methods for obtaining conductive copper patterns require high temperatures and complex equipment due to copper's high oxidation rate and the need for non-oxidative atmospheres, making them costly and inefficient for large-scale production.

Innovation Solution

A copper nanoparticle ink formulation containing a copper-oxidizing agent and copper hydride (CuH) that prevents copper oxide formation, allowing for sintering at lower temperatures in air, reducing equipment complexity and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional sintering methods are used for copper nanoparticles, then continuous metallic patterns can be obtained, but high temperatures (>150°C) and non-oxidative atmospheres are required, increasing equipment complexity and production costs

Engineering Contradiction:

Improveconductivity of copper patternsVSAvoidequipment complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces copper hydride (CuH) as an intermediary substance that mediates between copper nanoparticles and oxygen. CuH forms a protective layer around copper particles, preventing direct oxidation while allowing controlled decomposition at lower temperatures to facilitate sintering. This intermediary mechanism eliminates the need for complex non-oxidative atmosphere equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical state of copper from metallic (Cu⁰) to hydride form (CuH), which fundamentally alters the sintering behavior. This parameter change allows sintering to occur at lower temperatures (below 150°C) and in air atmosphere, replacing the conventional high-temperature non-oxidative sintering process and simplifying equipment requirements.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional sintering processes are used, then copper patterns can be formed, but prolonged heating times are required, reducing production efficiency

Engineering Contradiction:

Improvecontinuity of copper patternsVSAvoidproduction efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent utilizes the phase transition of copper hydride decomposition (CuH → Cu + H₂) as a driving force for sintering. This exothermic decomposition provides localized heat and hydrogen atmosphere that promotes rapid particle bonding, reducing sintering time from hours to minutes while ensuring continuous pattern formation.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The copper hydride is pre-formed on the nanoparticle surfaces before sintering, creating a reactive layer that enables immediate low-temperature sintering upon heating. This preliminary chemical modification eliminates the need for prolonged heating to reduce surface oxides, significantly accelerating the production process.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If copper nanoparticles are used for conductive patterns, then lower material cost is achieved compared to silver, but spontaneous oxidation and native oxide layer formation hinder sintering, requiring complex processing

Engineering Contradiction:

Improvematerial costVSAvoidease of sintering process

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The invention converts the harmful oxidation tendency of copper into a beneficial process by using copper hydride decomposition. The hydride layer protects copper from harmful oxidation during storage and printing, then decomposes controllably during sintering to provide a reducing atmosphere that actually promotes metal-metal bonding, turning the oxidation problem into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent creates a composite structure where copper nanoparticles are coated with copper hydride layer. This composite material combines the low cost and high conductivity of copper with the protective and reactive properties of CuH, enabling easy sintering in air without requiring complex inert atmosphere equipment or prolonged processing.

Inventive Principle:

Principle #40Composite materials

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

Enables fast and cost-effective production of highly conductive copper patterns with reduced sintering temperatures and durations, maintaining high conductivity and stability.

Implementation Method 1

The unique ink formulation prevents formation of copper oxide during storage and subsequent printing and sintering

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Implementation Method 2

heating the printed precursor to high temperatures (>150° C.)

Methodology Applied

Scientific EffectThermal decomposition: Decomposition (biological)

Implementation Method 3

sintering is a process in which distinct particles of matter are heated to cause solid-state diffusion-driven bonding of the particles into a solid or substantially continuous mass

Methodology Applied

Scientific EffectSintering: Sintering