Copper Oxide Ink for Low-Resistance Conductive Patterns
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Solution Overview
Problem
The existing direct circuit printing technology using metal inks or pastes faces challenges in maintaining low resistivity stability over time due to oxidation issues, particularly with silver pastes, and lacks stability at high concentrations, affecting the industrial applicability of the conductive films formed.
Innovation Solution
A copper oxide ink comprising copper oxide, a dispersant, and a reducing agent, with specific mass ratios and acid values, is used to form a conductive pattern on a substrate, where the reducing agent promotes reduction of copper oxide to copper during firing, enhancing dispersion and storage stability, and the dispersant prevents agglomeration, allowing for low-temperature firing using plasma or light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If copper ultrafine particles are used to form thin conductive films, then the film thickness is reduced and conductivity is improved, but oxidation occurs readily leading to increased resistivity over time
Solution Approach 1:
The patent uses copper oxide as an intermediary substance instead of直接用铜超细粒子。铜氧化物在空气中稳定，不氧化，作为中间态物质，在需要导电性时才通过还原处理转化为铜，从而解决了铜超细粒子易氧化导致电阻率升高的问题
Solution Approach 2:
通过控制还原处理的参数（如还原剂用量、处理条件等）来实现铜氧化物到铜的转化。专利中通过精确控制还原剂的质量百分比含量，使得铜氧化物在适当条件下还原为铜，形成导电网络，既保证了导电性又避免了过早氧化
2Reliability
If antioxidation treatment is applied to copper ultrafine particles, then oxidation is prevented, but sintering is hindered
Solution Approach 1:
专利采用铜氧化物作为预处理形式，在空气中稳定存在，避免了抗氧化处理对烧结的负面影响。铜氧化物本身具有良好的烧结性能，在还原处理前可以正常进行烧结工序，烧结后再通过还原处理获得导电性的铜薄膜
Solution Approach 2:
铜氧化物作为中间物质，既具有抗氧化性又具有良好的烧结性能。通过这个中间态，巧妙地避开了直接对铜超细粒子进行抗氧化处理会导致的烧结困难问题
3Volume of moving object
If metal paste with micrometer-sized particles is used, then thick metal films are formed, but the particle size is large requiring high viscosity dispersion
Solution Approach 1:
专利采用纳米级铜氧化物粒子（3-50nm）替代微米级金属粒子，通过改变粒子尺寸参数，使得分散液粘度降低，流动性改善，便于印刷加工。同时通过控制还原处理后铜粒子的堆积和烧结，形成适当厚度的导电膜
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 solution achieves high dispersion and storage stability of the conductive film with low resistance, enabling the formation of conductive patterns suitable for various applications, including electrical conductivity and antibacterial properties.
Implementation Method 1
reducing the copper oxide to copper by energy such as heat or active light rays in a suitable atmosphere
Implementation Method 2
a dispersion in which microparticles selected from a group consisting of metal microparticles and metal oxide microparticles are dispersed
Implementation Method 3
low-temperature firing using plasma or light
Implementation Method 4
reducing the copper oxide to copper by energy such as heat or active light rays
Implementation Method 5
the ultrafine copper particles mutually form fine random chains due to sintering, and the whole becomes a network whereby the desired electrical conductivity is obtained
Data Source
Figure 1
Figure 2A~2D
Figure 3(a)~3(h)
AI summary
In the present invention, a conductive film having low resistance is formed on a substrate, said film having excellent storage stability and high dispersion stability as an ink. A copper oxide ink (1) contains a copper oxide (2), a dispersant (3), and a reducing agent. The content of the reducing agent is in the range of formula (1), and the content of the dispersant is in the range of formula (2). (1) 0.00010 ≤ (reducing agent mass/copper oxide mass) ≤ 0.10 (2) 0.0050 ≤ (dispersant mass/copper oxide mass) ≤ 0.30 The reducing agent content promotes the reduction of copper oxide to copper during firing, and promotes the sintering of copper.