Electromechanical properties of printed copper ink film using a white flash light annealing process for flexible electronics

Title
Electromechanical properties of printed copper ink film using a white flash light annealing process for flexible electronics
Authors
은경태전민우유태희송용원좌성훈
Keywords
Intensive pulsed light; Annealing; Cu ink film; Flexibility; Stretchability
Issue Date
2015-04
Publisher
Microelectronics reliability
Citation
VOL 55, NO 5, 838-845
Abstract
We report on a systematic study of the electromechanical properties of flexible copper (Cu) thin film for flexible electronics. Cu ink is synthesized with chemical reduction process. Cu ink film spin-coated on a polyimide substrate is annealed with white flash light, also known as intense pulsed light (IPL), which guarantees a room temperature and sub-second process in ambient conditions. IPL annealed Cu film shows the electrical resistivity of 4.8 μΩ cm and thickness of 200 nm. The electromechanical properties of IPL annealed Cu film are investigated via outer/inner bending, stretching, and adhesion tests, and it is compared with conventional electron-beam evaporated Cu film. IPL annealed Cu film shows a constant electrical resistance within a bending radius of 6 mm. The bending fatigue test shows that the Cu film can withstand 10,000 bending cycles. In the stretching test, the Cu film shows a 50% increase in resistance when a strain of 2.4% was induced. At 4% strain, the resistance increases more than 200%. Meanwhile, the electron-beam evaporated film shows a constant resistance up to a strain of 4%. Lower stretchability of IPL annealed Cu film is attributed to its inherent cracks and porous film morphologies. IPL annealing induces the local melting at the interface between the substrate and Cu film, which increases the adhesion strength of the Cu film. These results provide useful information regarding the mechanical flexibility and durability of the nanoparticle films for the development of flexible electronics.
URI
http://pubs.kist.re.kr/handle/201004/50191
ISSN
00262714
Appears in Collections:
KIST Publication > Article
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