Reliability of Screen Printed Vias for a Flexible Energy Harvesting and Storage Module Designed for Internet of Everything Applications
Kujala, Manu (2018)
Kujala, Manu
2018
Sähkötekniikka
Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering
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Hyväksymispäivämäärä
2018-04-04
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201803201405
https://urn.fi/URN:NBN:fi:tty-201803201405
Tiivistelmä
Internet of Things (IoT) and Internet of Everything (IoE) concepts will have significant impact on the electronics market. These concepts require high volume and cheap electronics fabrication methods, which should be environmentally friendly as well. Printed Electronics (PE) enables novel materials on various substrates, that can be thin, light, flexible or stretchable. In the future, electronics can be implemented in the surroundings and are available whenever users need it. The vision is that all surrounded electronics are connected to the internet and are energy autonomous. Electronic devices can then gather energy from the environment and store it.
This thesis introduces an energy module, which can gather energy from ambient light with an organic solar cell and store it into an electrolytic double layer capacitor, also known as ultra- or supercapacitor. Both components can be printed on flexible substrates with PE methods. These components share the same substrate and the interconnection between them is done with a printed through-hole via and silver ink. The printed throughhole via’s printability and reliability is evaluated with a direct screen-printing method and cyclic bending test.
The results show that supercapacitor and organic solar cell -energy module can power up low energy electronic devices for short time periods. Roll-to-roll processing of the energy module is evaluated and a proposal of the energy module design is given. In the throughhole interconnection study, it is shown that the lower viscosity silver ink does not fill the via properly, but only to the sidewall of the via. This might lead to a poor interconnection between top and bottom of the substrate. Higher viscosity silver paste fills the via better and with 100 µm via size 100 % yield (n = 1010 vias) is achieved with this direct screenprinting method. The cyclic bending test showed no critical breakdown of the via even after 500 000 bending cycles. Using the direct screen-printing method in the roll-to-roll process enables multi-layered PE devices.
This thesis introduces an energy module, which can gather energy from ambient light with an organic solar cell and store it into an electrolytic double layer capacitor, also known as ultra- or supercapacitor. Both components can be printed on flexible substrates with PE methods. These components share the same substrate and the interconnection between them is done with a printed through-hole via and silver ink. The printed throughhole via’s printability and reliability is evaluated with a direct screen-printing method and cyclic bending test.
The results show that supercapacitor and organic solar cell -energy module can power up low energy electronic devices for short time periods. Roll-to-roll processing of the energy module is evaluated and a proposal of the energy module design is given. In the throughhole interconnection study, it is shown that the lower viscosity silver ink does not fill the via properly, but only to the sidewall of the via. This might lead to a poor interconnection between top and bottom of the substrate. Higher viscosity silver paste fills the via better and with 100 µm via size 100 % yield (n = 1010 vias) is achieved with this direct screenprinting method. The cyclic bending test showed no critical breakdown of the via even after 500 000 bending cycles. Using the direct screen-printing method in the roll-to-roll process enables multi-layered PE devices.