Silver Ink Composition for High Conductivity With Lower Silver Content
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Solution Overview
Problem
Conductive ink compositions face challenges in achieving high electric conductivity while maintaining low raw material costs, as reducing silver powder content lowers binder resin amounts, leading to poor screen printability and difficulty in forming conductive paths within short baking times.
Innovation Solution
A conductive ink composition with flake-shaped silver powder and high molecular weight binder resin, optimized with oleic acid surfactant coverage to maintain particle stability and reduce excess fatty acids, achieving a silver powder content of 45-70% and binder resin content of 5-15% by weight, with an ink viscosity of 10-25 Pa·s, allowing for high conductivity and low material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver powder content is reduced to lower raw material costs, then cost decreases, but electric conductivity and screen printability deteriorate
Solution Approach 1:
The patent changes the particle size parameter of silver powder to 3 μm or less, which increases surface area and improves conductivity. It also optimizes the binder resin molecular weight to 20,000 or less and controls fatty acid content to 50 ppm or less, creating a combination of parameters that achieves high conductivity with reduced silver content
Solution Approach 2:
The patent creates a composite ink composition combining ultrafine silver powder with specific binder resins and controlled fatty acid amounts. This composite approach allows the system to achieve properties (high conductivity, good printability) that individual components cannot provide alone, enabling reduced silver content while maintaining performance
2Reliability
If binder resin amount is reduced to lower costs, then raw material cost decreases, but screen printability and ink viscosity deteriorate
Solution Approach 1:
The patent optimizes the molecular weight parameter of the binder resin to 20,000 or less, which provides adequate viscosity and printability with minimal resin content. It also controls the binder resin content to 5-20% by weight, achieving the right balance between cost reduction and maintaining screen printability
3Reliability
If baking time is extended to achieve high conductivity, then electric conductivity improves, but production efficiency and productivity decrease
Solution Approach 1:
The patent changes multiple parameters simultaneously: ultrafine silver powder (3 μm or less) for rapid sintering, low molecular weight binder resin (20,000 or less) for fast evaporation, and controlled fatty acid content (50 ppm or less) to prevent oxidation. This parameter combination enables high conductivity to be achieved in just 60 seconds at 150°C
Solution Approach 2:
The patent performs preliminary surface treatment of silver powder by controlling fatty acid content to 50 ppm or less before printing. This preliminary action prevents oxidation and prepares the surface for rapid bonding during the short 60-second baking process, enabling quick achievement of high conductivity without extended baking time
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 ink composition achieves high electric conductivity of 20 μΩ·cm or less under a short baking condition of 150°C for 60 seconds, with improved printability and reduced raw material costs, while minimizing coarse particles and maintaining stability.
Implementation Method 1
containing a conductive metal particle (A) having an oleic acid surfactant
Implementation Method 2
oleic acid surfactant coverage to maintain particle stability
Implementation Method 3
under a short baking condition of 150°C for 60 seconds
Implementation Method 4
drying or hardening a printed coating film
Implementation Method 5
achieving high conductivity and low material costs
Implementation Method 6
highly conductive silver ink composition... achieves high electric conductivity of 20 μΩ·cm or less
Data Source
AI summary
A conductive ink composition for screen printing contains a conductive metal particle (A) having an oleic acid surfactant, a non-chlorine-based resin composition (B), and an organic solvent (C), wherein the conductive metal particle (A) is contained in an amount of 45 to 70% by weight with respect to the total ink composition, the non-chlorine-based resin composition (B) has a number average molecular weight of 50,000 or more and is contained in an amount of 5 to 15% by weight with respect to the total ink composition, the organic solvent (C) has a flash point of 75 to 110° C. and is contained in an amount of 25 to 50% by weight with respect to the total ink composition, and the ink composition has an ink viscosity of 10 to 25 Pa·s (23° C.) at a shear rate of 100 s−1.