TERAHERTZ QUALITY CONTROL OF PRINTED INK
Characterize the quality of the distribution of the ink in printed electronics
The challenge in printed electronic devices testing and production
- Printable electronics is an advanced technology for manufacturing electronic circuits on flexible substrates.
- Printing of an electronic device generally involves depositing a conductive ink on a substrate in a predetermined position to form conductive traces.
- The printing of such electronic circuits can be performed using conventional printing techniques suitable for depositing patterns on substrates. It enables the production of widespread, low-cost, and low-performance electronic devices for applications varied from flexible displays to biomedical sensors.
- The main key of any production process is a well-established quality control.
- In printable electronics, the accuracy of the ink deposition in some or all of the electronic devices during the fabrication process is one of the main tracking parameters.
- For instance, if the conductivity or the distribution of the deposited ink during printing drifts over time, the operability of the resulting printed electronic devices could be negatively affected.
- Nowadays, there are many techniques to measure the conductivity of printed electronic devices or to test the ink deposition accuracy during the printing process. It involves manual post-processing characterizations or imaging of the printed electronic device with a limited resolution, which is thereby limiting the ink quality assessment.
- There is a need to find a non-destructive and in-situ solution to control the printing quality including the ink conductivity, the distribution of deposited ink and the expected dimensional accuracy of printed electronics.
Assessing and controling the quality of the ink deposition accuracy
- The invention incorporates a system and a method to assess and control the quality of the ink deposition accuracy during the printing process of an electronic device.
- A testing system for controlling the quality of an electronic device printed on a substrate using a conductive ink with a resonating pattern (metamaterials) printed on the side of the main production line.
- The testing system of an electronic device consists of a terahertz radiation emitter and a terahertz radiation receiver placed at specific locations from the testing pattern to verify the quality in the real time, and a controller configured to determine a conductivity value indicative of a conductivity of the ink or the ink distribution.
- The method is based on printing of testing patterns in some places of printing on the substrate and validating their conductivities at regular intervals, emitting a terahertz radiation beam incident onto the testing metamaterials structure on the substrate to produce an outgoing terahertz radiation beam having a spectral response at least at the terahertz resonance frequency, measuring the spectral response of the outgoing terahertz radiation beam, assessing the ink deposition accuracy of the printing based on the measured spectral response, and generating a signal indicative of the assessed ink deposition accuracy.
- Technology developed by prof. François Blanchard and Mariia Zhuldybina at École de Technologie supérieure
- Contactless, non-destructive method, therefore ideal for a high-speed industrial production
- Using of multiple terahertz frequencies or single frequency
- Opening the doors for using terahertz CMOS emitters and receivers
- Allowing inline tracking to possibly have a direct feedback on the printer conditions
- Simple and accurate in-situ method to characterize the distribution of the ink at the industrial scale
- Currently, there is no other method for non-invasive and in-situ quality control of printed electronic devices
- Printed electronic devices manufacturing
- Companies that convert their paper printing business to manufacturing printable electronics devices
- Roll-to-Roll printing market for flexible electronic devices
- Technology available for licensing
- Provisional patent application filed
École de Technologie supérieure (ÉTS)
François Blanchard, Professor, Electric Engineering Department
François Blanchard Eng., M.Sc., Ph.D. has joined ÉTS in 2015 and he recently obtained the ÉTS Research Chair on terahertz (THz) optoelectronic. Among his research achievements, he is internationally recognized for his research on intense terahertz pulse generation and the development of a video-rate terahertz microscope system. Since 2015, he has supervised 7 M.Sc.A, 4 Ph.D., and 2 PDFs. and has given 10 invited talks at national/international conferences. Additionally, professor Blanchard cumulates 10 years of industrial field experiences in non-destructive testing of materials.
Mariia Zhuldybina, Researcher, Electric Engineering Department
Mariia Zhuldybina B.ASc., M.ASc., currently is a Ph.D. student in the Electrical Engineering Department at ÉTS. Her research interest includes developing the in-line and non-destructive quality control technique of printed electronics with terahertz spectroscopy for industrial applications.