Air-Fired Copper Electrode with Boron Oxidation Inhibition
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Solution Overview
Problem
The challenge is to create an electrode with low resistivity using copper powder as the conductive material, which oxidizes during the firing process, increasing resistivity, while maintaining cost-effectiveness by avoiding expensive inert environments like nitrogen filling systems.
Innovation Solution
A conductive paste comprising copper powder, boron powder to inhibit oxidation, zirconia powder for low resistivity, and glass frit for sintering, applied and fired in air, optimizing the composition and firing conditions to achieve low resistivity and fine pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper powder is used as conductive material and fired in air, then production cost is reduced, but copper oxidizes and resistivity increases
Solution Approach 1:
Boron powder is introduced as an intermediary substance that reacts with oxygen during firing to form a protective boron oxide layer, preventing copper oxidation. This mediator allows air firing to proceed while protecting the copper conductive material from harmful oxidation effects.
Solution Approach 2:
The conductive paste is formulated as a composite material containing copper powder (conductive), boron powder (oxidation inhibitor), glass frit (sintering aid), and organic vehicle. This composite structure enables air firing while maintaining low resistivity through the synergistic effects of its components.
2Ease of manufacture
If base metal such as aluminum or nickel is used instead of copper, then cost is reduced, but oxidation resistance is improved at the expense of conductivity
Solution Approach 1:
The invention uses inexpensive copper powder that would normally be susceptible to oxidation, but protects it temporarily during the firing process using boron powder as a sacrificial antioxidant. This allows the use of cheap copper instead of more expensive oxidation-resistant base metals like nickel or aluminum.
3Reliability
If glass frit is added to the conductive paste, then sintering is improved and low resistivity is achieved, but the composition complexity increases
Solution Approach 1:
Glass frit serves multiple functions simultaneously: it acts as a sintering aid to densify the electrode, forms a protective matrix that prevents copper oxidation, and contributes to the overall mechanical strength and adhesion of the fired electrode. This multi-functionality justifies the added compositional complexity.
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 enables the production of electrodes with low resistivity and fine patterns at a reduced cost by air firing, effectively inhibiting copper oxidation and maintaining conductivity, thus decreasing production costs for electronic devices.
Implementation Method 1
a conductive paste comprising a copper powder, a boron powder, an additional inorganic powder, a glass frit, and an organic medium... wherein the additional inorganic powder is zirconia powder
Implementation Method 2
a conductive paste comprising a copper powder, a boron powder, an additional inorganic powder, a glass frit, and an organic medium... firing the dried conductive paste in air
Implementation Method 3
the additional inorganic powder is zirconia powder... that has low resistivity
Data Source
AI summary
The invention relates to an electrode that can be formed by firing in air a conductive paste comprising a copper powder, a boron powder, an additional inorganic powder, a glass frit, and an organic medium, wherein the additional inorganic powder is zirconia powder.