Sintered Silver Conductive Ink via Pulsed UV Decomposition
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Solution Overview
Problem
Existing methods for creating conductive networks using silver face challenges in achieving both high conductivity and strong adhesion to substrates, particularly with nanosilver particles, which require complex synthetic routes and surfactants, and precursor methods that necessitate binders hindering sintering.
Innovation Solution
A method involving a conductive ink composition of a silver compound and a binder, where external energy sources like pulsed UV radiation are used to decompose and sinter elemental silver in situ, enhancing adhesion without high-temperature requirements, suitable for sensitive substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanosilver particles are used to achieve low sintering temperature and sufficient conductivity, then conductivity is improved, but adhesion to substrates becomes weak
Solution Approach 1:
The invention extracts and removes the binder from the sintering process by using a two-stage approach: first forming the conductive network through binder removal and sintering, then adding a separate adhesion promoter layer. This separates the conflicting functions of binder (which aids adhesion but hinders sintering) from the sintering process itself, resolving the contradiction between conductivity and adhesion.
2Strength
If binders are added to enhance adhesion of silver precursor inks, then adhesion is improved, but sintering is hindered and conductivity decreases
Solution Approach 1:
The invention performs preliminary binder removal through controlled heating before sintering. By removing the binder in advance (preliminary action), the sintering process can proceed without interference, achieving both good adhesion (from the initial binder presence) and high conductivity (from uninterrupted sintering).
Solution Approach 2:
The invention uses periodic heating cycles with different temperature stages: first a lower temperature stage to remove the binder, then a higher temperature stage to sinter the silver particles. This periodic thermal treatment resolves the contradiction by sequentially achieving adhesion preparation and conductivity optimization.
3Reliability
If high temperature sintering is used to overcome contact resistance in micron scale silver flakes, then conductivity is improved, but substrate tolerance is exceeded
Solution Approach 1:
The invention changes the particle size parameter from micron scale to nanoscale, which fundamentally alters the sintering temperature requirement. Nanosilver particles have higher surface area to volume ratio and more surface atoms, enabling sintering at much lower temperatures (below substrate damage thresholds) while achieving equivalent or better conductivity.
4Ease of manufacture
If micron scale silver flakes are used to reduce material cost, then manufacturing cost is reduced, but contact resistance increases conductivity
Solution Approach 1:
The invention transitions from zero-dimensional powder particles to one-dimensional nanowires and nanorods. This dimensional change provides continuous or near-continuous conductive paths instead of discrete particle contacts, achieving low contact resistance while using cost-effective nanoscale materials that can be processed at low temperatures.
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
This method enables the formation of conductive silver networks with commercially usable conductivity and strong adhesion to substrates, even on sensitive materials like plastic and paper, by generating silver nanoparticles in situ and sintering them using pulsed UV radiation.
Implementation Method 1
applying an external energy source to the elemental silver to decompose the conductive ink to elemental silver
Implementation Method 2
sinter the elemental silver into a conductive network
Implementation Method 3
applying an external energy source to the deposited conductive ink to dry the ink
Data Source
AI summary
A method for making a conductive network of sintered silver comprises preparing a conductive ink comprising a silver compound and a binder; depositing the conductive ink on a substrate and applying an external energy source to the deposited conductive ink to dry the ink; and applying an external energy source to the dried ink to decompose the ink to elemental silver and to sinter the elemental silver into a conductive network.