Hong, P., Chin Yuan, G. S., Tan, Y. M., & Wan, K. (2025). Empowering Smart Surfaces: Optimizing Dielectric Inks for In-Mold Electronics. The 1st International Conference on AI Sensors & the 10th International Symposium on Sensor Science, 8. https://doi.org/10.3390/engproc2024078008
Abstract:
Dielectric materials have gained traction for their energy-storage capacitive and electrically
insulating properties as sensors and in smart surface technologies such as in In-Mold Electronics
(IME). IME is a disruptive technology that involves environmentally protected electronics in plastic
thermoformed and molded structures. The use of IME in a human–machine interface (HMI) provides
a favorable experience to the users and helps reduce production costs due to a smaller list of parts and
lower material costs. A few functional components that are compatible with one another are crucial
to the final product’s properties in the IME structure. Of these components, the dielectric layers
are an important component in the smart surface industry, providing insulation for the prevention
of leakage currents in multilayered printed structures and capacitance sensing on the surface of
specially designed shapes in IME. Advanced dielectric materials are non-conductive materials that
impend and polarize electron movements within the material, store electrical energy, and reduce
the flow of electric current with exceptional thermal stability. The selection of a suitable dielectric
ink is an integral stage in the planning of the IME smart touch surface. The ink medium, solvent,
and surface tension determine the printability, adhesion, print quality, and the respective reaction
with the bottom and top conductive traces. The sequence in which the components are deposited
and the heating processes in subsequent thermoforming and injection molding are other critical
factors. In this study, various commercially available dielectric layers were each printed in two to
four consecutive layers with a mesh thickness of 50–60 μm or 110–120 μm, acting as an insulator
between conductive silver traces overlaid onto a polycarbonate substrate. Elemental mapping and
optical analysis on the cross-section were conducted to determine the compatibility and the adhesion
of the dielectric layers on the conductive traces and polycarbonate substrate. The final selection was
based on the functionality, reliability, repeatability, time-stability, thickness, total processing time,
appearance, and cross-sectional analysis results. The chosen candidate was then placed through the
final product design, circuitry design, and plastic thermoforming process. In summary, this study
will provide a general guideline to optimize the selection of dielectric inks for in-mold electronics
applications.
License type:
Publisher Copyright
Funding Info:
There was no specific funding for the research done