Conductive Paste Stability via Epoxy Resin and Silane Coupling
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Solution Overview
Problem
Conductive pastes used for forming electrodes and electrical wiring face issues with stability over time, leading to quality deterioration and increased viscosity, especially when silver-coated resins are used, which can result in poor conductivity and printing performance.
Innovation Solution
A conductive paste comprising a silver-coated spherical resin with a thermosetting epoxy resin composition, a curing agent, and a solvent, where the epoxy resin is solid at room temperature and has a melt viscosity of 0.5 Pa·s or lower at 150°C, and the silver coating is characterized by a crystallite diameter of 18-24 nm, ensuring improved stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silver-coated resin is used as conductive filler to reduce cost, then manufacturing cost is reduced, but paste viscosity increases over time and quality deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the organic vehicle by specifying exact proportions of phosphoric acid (0.1-10 wt%), silane coupling agent (0.1-5 wt%), and their molar ratios. These parameter adjustments stabilize the paste composition over time, preventing viscosity increase while maintaining the cost advantage of using silver-coated resin particles.
Solution Approach 2:
The patent introduces phosphoric acid and silane coupling agent as intermediary substances that mediate between the silver-coated resin particles and the organic vehicle. These intermediaries prevent direct adverse reactions between the resin coating and other paste components, thereby stabilizing paste quality over time while allowing the use of lower-cost silver-coated resin.
2Reliability
If conventional conductive paste is used, then initial conductivity is achieved, but conductivity deteriorates after long-term storage
Solution Approach 1:
The patent applies phosphoric acid and silane coupling agent as protective treatments beforehand to the organic vehicle formulation. This prior cushioning prevents future quality deterioration by stabilizing the chemical environment, ensuring that conductivity is maintained over extended storage periods while achieving good initial conductivity performance.
Solution Approach 2:
The patent creates a composite organic vehicle system combining phosphoric acid, silane coupling agent, and other components in specific ratios. This composite formulation provides both immediate conductivity support and long-term stability, preventing conductivity deterioration over time while maintaining reliable initial performance.
3Strength
If thermosetting resin with high melt viscosity is used, then adhesion strength is improved, but printing performance deteriorates
Solution Approach 1:
The patent adjusts the chemical composition parameters of the organic vehicle, specifically the concentrations of phosphoric acid (0.1-10 wt%) and silane coupling agent (0.1-5 wt%), which modify the resin's flow characteristics. These parameter changes enable the resin to maintain adequate adhesion strength while achieving suitable printing performance by optimizing the balance between bonding capability and flowability.
Solution Approach 2:
The patent applies silane coupling agent as a localized modifier that enhances adhesion at the interface between the conductive paste and substrate, while the bulk organic vehicle maintains appropriate flow properties for printing. This local quality enhancement allows strong adhesion without compromising printing performance.
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 conductive paste maintains high conductivity and printing performance even after long-term storage, reducing the risk of quality deterioration and allowing for the formation of electrodes with strong adhesion and high heat resistance at a lower cost.
Implementation Method 1
it has become increasingly important to use an organic vehicle containing phosphoric acid and a silane coupling agent
Implementation Method 2
a silver-coated spherical resin in which a surface of a resin is coated with silver
Implementation Method 3
an organic vehicle which includes a thermosetting resin composition, a curing agent, and a solvent
Data Source
AI summary
A conductive paste includes: a silver-coated resin; and an organic vehicle that includes a thermosetting resin composition, a curing agent, and a solvent, in which the thermosetting resin composition is an epoxy resin composition which is solid at room temperature and has a melt viscosity of 0.5 Pa·s or lower at 150°C, and a mass ratio of a content of the thermosetting resin composition to a content of the silver-coated resin is 10 to 40:60 to 90.