Photosensitive Paste for Low-Resistance Copper Electrodes
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Solution Overview
Problem
Existing methods for forming electrodes using photosensitive pastes face challenges in using inexpensive copper powder, air firing, achieving fine patterns, and maintaining low resistance, as copper oxidation increases resistance and boron scattering affects pattern quality.
Innovation Solution
A photosensitive paste composition with copper powder of 2.5 μm or less average particle size and 8-25 wt% boron powder, fired in air, which inhibits copper oxidation and maintains low electrode resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copper powder is used as the conductive component, then material cost decreases, but copper oxidizes easily requiring firing under nitrogen atmosphere which increases capital investment
Solution Approach 1:
Boron powder is introduced as an intermediary substance that reacts with oxygen during air firing to form a protective boron oxide layer, preventing copper oxidation without requiring a nitrogen atmosphere, thus resolving the contradiction between using inexpensive copper and avoiding complex firing conditions
Solution Approach 2:
The chemical composition parameters of the paste are changed by adding boron powder at specific concentrations (0.1-10 wt% based on copper powder content), which alters the oxidation behavior during firing, enabling air firing while maintaining copper conductivity
2Ease of manufacture
If boron is added to inhibit copper oxidation during air firing, then air firing becomes possible, but boron scatters light adversely affecting pattern shape
Solution Approach 1:
The particle size parameter of boron powder is optimized to 10 μm or smaller, and its concentration is controlled at 0.1-10 wt% relative to copper powder. These parameter changes reduce light scattering effects while maintaining the oxidation protection function, thus resolving the contradiction between air firing capability and pattern precision
3Manufacturing precision
If small particle size copper powder is used to obtain fine line configuration, then pattern resolution improves, but surface area increases causing easier oxidation
Solution Approach 1:
Boron powder serves as a protective intermediary that forms an oxide barrier around fine copper particles during air firing, preventing oxidation of the high-surface-area fine copper powder while maintaining the fine line pattern quality
Solution Approach 2:
The paste forms a composite material system combining copper powder (conductive component) and boron powder (protective component), where the boron provides oxidation resistance to the fine copper particles, enabling both fine pattern formation and oxidation protection
4Reliability
If large amount of boron is added to inhibit oxidation, then oxidation resistance improves, but electrode resistance increases because boron has poor conductivity
Solution Approach 1:
The concentration parameter of boron powder is precisely controlled at 0.1-10 wt% based on copper powder content. This parameter optimization ensures sufficient oxidation protection while limiting boron's negative impact on conductivity, thus resolving the contradiction between oxidation resistance and electrode 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
The solution enables the formation of low-resistance, fine-patterned electrodes using air firing with inexpensive copper, reducing production costs and improving electrode quality.
Implementation Method 1
The applied photosensitive paste is exposed through a mask, and polymerization of the monomer proceeds at the exposed locations
Implementation Method 2
firing the developed photosensitive paste to form an electrode pattern
Data Source
AI summary
A low-resistance, fine electrode is formed by baking in air a photosensitive paste which has an inorganic component containing copper powder, boron powder, and glass frit, and an organic component containing a photopolymerization initiator, monomer, and organic vehicle, and in which the average particle size of the copper powder is 2.5 μm or less, and the content of boron powder based on the total amount of copper powder and boron powder is 8 to 25 wt %.