Presentation Information
[8a-B11-9]Characterization of thin film properties generated by atmospheric-pressure plasma irradiation on electrically-conductive-adhesive
〇Toru Sasaki1, Motoki Maegawa1, Yutaro Hanami1, Van-Phuoc Thai2, Kazumasa Takahashi1, Takashi Kikuchi1 (1.Nagaoka UT, 2.HCMUTE)
Keywords:
Atomospheric pressure plasma,electrically conductive adhesives
Silicone-based electrically conductive adhesives (SECAs) offer high conductivity, heat resistance, flexibility, and biocompatibility, making them valuable in electronic packaging, aerospace and automotive components, and wearable electronics. However, their metal fillers (e.g., silver nanoparticles) oxidize under humid, oxygen-rich, or high-temperature conditions, degrading conductivity over time - silver's conductivity drops from 107 to 103 S/m upon oxidation. Conventional protective methods, such as dual metal fillers or graphene oxide coatings, add material cost and processing time. This study shows that atmospheric-pressure plasma irradiation cures the adhesive while simultaneously forming a protective surface film. SECAs (XA-5940, 76 wt% Ag) were coated on glass, treated with dielectric barrier discharge plasma (He 5 slm, 11 kV, 35 kHz), and cured at 200 deg C for 1 h. Optical emission spectroscopy confirmed reactive radicals (OH, H, O, N2). Within minutes, an amorphous SiOxCy film formed, with thickness increasing with irradiation time (about 250 nm at 20 s, 810 nm at 2 min, up to 1000 nm at 5 min). XPS revealed the film consisted mainly of Si3+ and Si4+ with increased C-O bonding, differing from the Si2+/Si3+-dominated resin. The film was strongly hydrophobic (contact angle >120 deg) and did not alter conductivity. Film formation required solvents rather than plasma heat (max 60 deg C). The plasma-treated samples maintained stable resistivity in 0.1 M HCl for 7 days and under ozone exposure for 20 min, demonstrating excellent oxidation resistance.