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0Direct laser metallization from deep eutectic solvents on polymer substrates
L. Logunov1*, E. Khairullina1, A. Shishov3, A. Komlev2, D. Shestakov2
1- School of Physics and Engineering, ITMO University, Lomonosova, 9, Saint-Petersburg, 191002, Russia
2- Department of Physical Electronics and Technology, Saint Petersburg Electrotechnical University "LETI",
197376 Saint St. Petersburg 197376, Russia
3- Institute of Chemistry, Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034,
Russia
* levlogunov@gmail.com
Direct laser metallization is unique technic for one step metal deposition on almost any surface. Method based on chemical reaction which induced by ultra-fast heating under the focused laser irradiation. We have developed method for various metal deposition such as copper, nickel and others [1,2]. In previous works, we were unable to achieve deposition on polymer substrates due to overheating of the substrates. In this work, we developed new approach to reduce the required laser irradiation power density by using an additional photoactive layer above the deep eutectic solvent film. The DES composition used was the same as in previous work [2]. The properties of conductive copper structures on PDMS, PET and polyamide substrates were created and demonstrated. We achieved resistivity of copper substrates closed to pure copper, the resolution of method was min 60 ^m width and 1 ^m thickness of single structure.
The idea of new approach was focusing on decreasing the laser power density. That was caused by optical properties of DES. As we used 1064 nm picosecond laser, DES has weak extinction coefficient on that wavelength, that leads to use high power density of laser irradiation to heat the film up to necessary temperature, but after the first milliseconds of deposition nucleates of metal start to absorb the laser light dramatically. Extra heating transfer appears to the substrate and in case of polymer substrates excess heat causes damage to the substrate. We added a thin black color layer above DES film using simple by whiteboard marker. We achieved the effect of reducing the power density by 5 -6 times, while the quality of the resulting structures greatly improved, since the excess laser radiation density did not lead to damage to the center of the resulting structures during a single scan.
Finally, we created prototypes of different electronic devises on flexible polymer substrates, such as RFID tag, microheaters, electrochemical sensors and circuit board. In this work we show their properties and application field. Direct laser metallization from deep eutectic solvents is a new ecological, simple and cheap method for device fabrication in small batches.
Acknowledgements: This work was supported by the Ministry of Science and Higher Education of the Russian Federation (Project No. 075-15-2024-625).
[1] E.M. Khairullina, I.I. Tumkin, D.D. Stupin, A.V. Smikhovskaia, A.S. Mereshchenko, A.I. Lihachev, A.V. Vasin, M.N. Ryazantsev, M.S. Panov, Laser-assisted surface modification of Ni microstructures with Au and Pt toward cell biocompatibility and high enzyme-free glucose sensing, ACS omega, 6(28), pp.18099-18109, (2021).
[2] D. Shestakov, E. Khairullina, A. Shishov, S. Khubezhov, S. Makarov, I. Tumkin, L. Logunov, Picosecond laser writing of highly
conductive copper micro-contacts from deep eutectic solvents, Optics & Laser Technology, 167, p.109777, (2023).
