Direct Writing Metal Features via Plasma Treatment
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Solution Overview
Problem
Conventional planar processing methods for electronic-component fabrication are limited by high material waste, substrate size constraints, low throughput, and incompatibility with flexible substrates, and existing inkjet printing technologies face challenges with metal-salt-based inks requiring high vacuum and temperature treatments, leading to non-uniform features and material parameter control issues.
Innovation Solution
The use of particle-free metal-salt-based inks dissolved in multi-part solvents for inkjet printing, followed by atmospheric-pressure microplasma post-deposition treatment, allowing for controlled conversion of metal salts to pure metal with varying material parameters across different regions or features, enabling uniform morphology and porosity control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional planar processing methods are used for metal layer deposition, then excellent pattern fidelity and small feature sizes are achieved, but high material waste occurs and substrate size is limited
Solution Approach 1:
The patent replaces conventional mechanical vapor deposition systems (PVD, sputtering) with an inkjet printing system that deposits metal salt solutions directly onto substrates. This substitution enables additive manufacturing of metal features without the material waste inherent in subtractive patterning methods, while maintaining the ability to achieve precise patterns through digital control of the inkjet deposition process
Solution Approach 2:
The patent changes the physical and chemical parameters of metal deposition by using solution-processed metal salt inks instead of vapor-phase metal deposits. This parameter change allows for direct writing of metal features with controlled morphology and enables subsequent conversion to pure metal through plasma treatment, eliminating the need for high-energy deposition processes that waste material
2Reliability
If evaporative or sputter deposition is used for metal layer formation, then metal layers are successfully deposited, but substrate size is constrained and system cost increases
Solution Approach 1:
The inkjet printing system described in the patent is universally applicable to substrates of any size, unlike evacuated chamber systems that are limited by chamber dimensions. The same inkjet printing process can deposit metal features on small flexible substrates for wearable electronics or large rigid substrates for conventional electronics, making the system multi-functional and substrate-size agnostic
3Ease of manufacture
If conventional planar processing is used for electronics fabrication, then rigid substrates are processed effectively, but flexible substrates cannot be accommodated
Solution Approach 1:
The patent uses solution-processed metal salt inks that can be deposited at low temperatures compatible with flexible polymer substrates. The subsequent plasma treatment parameters are controlled to convert metal salts to pure metal without exceeding the thermal tolerance of flexible substrates, enabling the same manufacturing process to work on both rigid and flexible materials
4Reliability
If metal nanoparticle colloidal-suspension inks are used for inkjet printing, then conductive features are formed, but clogging of ejector nozzles occurs
Solution Approach 1:
The patent changes the physical state of the metal ink from colloidal suspensions of metal nanoparticles to solutions of metal salts. This parameter change eliminates the clogging problem because metal salt solutions are particle-free and flow smoothly through inkjet nozzles, while still enabling the formation of conductive features through subsequent plasma-induced conversion to pure metal
5Reliability
If high vacuum and temperature treatments are applied to metal-salt-based inks, then conversion to pure metal is achieved, but non-uniform features and material parameter control issues occur
Solution Approach 1:
The patent changes the treatment parameters from high vacuum and high temperature to atmospheric pressure and low temperature plasma treatment. This parameter change enables precise control over the conversion process, producing uniform metal features with consistent material parameters while avoiding the non-uniformity caused by aggressive high-energy treatments
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 approach enables direct writing of metal features with consistent morphology and controlled material parameters on a wide range of substrates, including flexible ones, reducing material waste and processing costs, and allowing for diverse material properties within a single feature or across different features.
Implementation Method 1
exposing the deposited ink to a plasma that is operative for converting the metal salt into pure metal
Implementation Method 2
converting the metal salt into pure metal
Data Source
AI summary
A method for directly writing metal traces on a wide range of substrate materials is disclosed. The method includes writing a pattern of particle-free metal-salt-based ink on the substrate followed by a plasma-based treatment to remove the non-metallic components of the ink and decompose its metal salt into pure metal. The ink is based on a multi-part solvent whose components differ in at least one of evaporation rate, surface tension, and viscosity, which improves the manner in which the ink is converted into its metal constituent via the plasma treatment. In some embodiments, a microplasma is used for post-treatment of the deposited ink, where the plasma properties are controlled to provide different material properties, such as porosity and effective resistivity, in different regions of the metal pattern.