Copper Nanoparticle Ink for Low-Cost PCB Patterning
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Solution Overview
Problem
The high cost and complexity of patterning copper conductors on printed circuit boards (PCBs) due to the use of expensive silver inks and the chemical etching processes, which increase production costs and generate chemical waste.
Innovation Solution
The use of copper-based inks with nanoparticles that can be printed using inkjet technology and photosintered with a xenon lamp to form conductive lines, reducing the need for expensive silver and minimizing chemical waste through a low-temperature, low-energy process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver metal based inks are used for printing conductive lines, then electrical conductivity is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the material parameter from silver to copper nanoparticles, achieving a cost reduction of approximately 90% while maintaining acceptable conductivity for RFID and NFC applications. The copper-based ink formulation includes dispersants and binders optimized for inkjet printing, enabling low-cost production without sacrificing functional performance.
Solution Approach 2:
The invention replaces expensive silver materials with inexpensive copper nanoparticles, making the conductive ink a cost-effective consumable material suitable for mass production of RFID tags and NFC devices. This substitution aligns with the principle of using cheap materials when performance requirements are met.
2Manufacturing precision
If photolithography and acid etching processes are used for patterning copper, then manufacturing precision is improved, but loss of substance increases due to chemical waste
Solution Approach 1:
The patent replaces chemical etching processes with a physical printing approach using inkjet deposition of copper nanoparticles. The patterning is achieved through selective deposition and subsequent sintering, eliminating the need for chemical etchants and their associated waste streams while maintaining pattern definition.
Solution Approach 2:
The invention extracts and removes the chemical etching step from the traditional PCB manufacturing process. By using direct printing and sintering of copper nanoparticles, the process eliminates the acid etching stage entirely, thereby removing the source of chemical waste generation.
3Manufacturing precision
If traditional electroplating techniques are used for forming copper conductors, then manufacturing precision is improved, but loss of time increases due to multiple process steps
Solution Approach 1:
The patent merges multiple traditional process steps (copper deposition, patterning, and drying) into a single inkjet printing operation. The copper nanoparticle ink is deposited directly in the desired pattern, and subsequent low-temperature sintering completes the conductor formation, eliminating sequential electroplating and etching steps.
Solution Approach 2:
The invention performs preliminary action by pre-forming copper conductors through inkjet printing before final sintering. This allows the conductive pattern to be established in advance, and the sintering process merely consolidates the structure rather than requiring multiple iterative steps.
4Reliability
If high temperature processing is used for sintering metal particles, then electrical conductivity is improved, but use of energy increases
Solution Approach 1:
The patent changes the sintering temperature parameter from traditional high temperatures (>1000°C for bulk copper) to low temperatures (80-150°C) by utilizing the small particle size effect. Copper nanoparticles with diameters of 10-100 nm exhibit reduced melting and sintering temperatures, enabling energy-efficient processing while achieving adequate conductivity for the application.
Solution Approach 2:
The invention utilizes phase transition at reduced temperatures by exploiting the size-dependent melting point depression of nanoparticles. The copper nanoparticles undergo sintering and partial melting at temperatures far below bulk copper's melting point, enabling low-energy processing that still achieves the necessary conductive properties.
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 provides a cost-effective method for producing conductive copper lines with resistivity suitable for electronic interconnects and RFID tags, achieving high conductivity while reducing environmental impact and production costs.
Implementation Method 1
photosintered with a xenon lamp to form conductive lines
Implementation Method 2
a solution of metal ink is printed onto a substrate and the film is photosintered by exposing it to light from a flash lamp
Data Source
AI summary
Forming a conductive film comprising depositing a non-conductive film on a surface of a substrate, wherein the film contains a plurality of copper nanoparticles and exposing at least a portion of the film to light to make the exposed portion conductive. Exposing of the film to light photosinters or fuses the copper nanoparticles.