Silver inkjet printing with control of surface energy and substrate temperature

Abstract

The characteristics of silver inkjet printing were intensively investigated with control of surface energy and substrate temperature. A fluorocarbon (FC) film was spincoated on a silicon (Si) substrate to obtain a hydrophobic surface, and an ultraviolet (UV)/ozone (O 3 ) treatment was performed to control the surface wettability of the FC film surface. To characterize the surface changes, we performed measurements of the static and dynamic contact angles and calculated the surface energy by Wu's harmonic mean model. The surface energy of the FC film increased with the UV/O 3 treatment time, while the contact angles decreased. In silver inkjet printing, the hydrophobic FC film could reduce the diameter of the printed droplets. Merging of deposited droplets was observed when the substrate was kept at room temperature. Substrate heating was effective in preventing the merging phenomenon among the deposited droplets, and in reducing the width of printed lines. The merging phenomenon of deposited droplets was also prevented by increasing the UV/O 3 treatment time. Continuous silver lines in the width range of 48.04-139.21 µm were successfully achieved by inkjet printing on the UV/O 3 -treated hydrophobic FC films at substrate temperatures below 90 • C.

High-resolution CPW fabricated by silver inkjet printing on selectively treated substrate

“…Various factors can affect the shape and surface profile of the printed structure, such as viscosity of the ink, surface energy of the substrate, sintering temperature and duration, and temperature of the substrate during the printing process. More detailed analysis about the effect of these factors on the shape of the structure is shown in our previous research [6,7,16,17]. The thickness of the CPW is optically measured using a 3-D non-contact surface profilometer (Surf, Nanofocus AG, Germany).…”

“…The ink is printed using a drop-on-demand inkjet printer, Dimatrix DMP-2831 (DimatrixFujifilm Inc., USA), which is equipped with sixteen nozzles, each with a diameter of 19 m. A fluorocarbon solution is utilized to modify the substrate condition. The solution is prepared by dissolving Fluorad TM FC-722 (3M Co., South Korea) in Fluorinert TM FC-40 (3M Co., South Korea) with the volume ratio of 1:4, where the surface of the spin-coated solution is known to have good hydrophobicity [15,16]. A Borofloat ® 33 borosilicate glass wafer with a thickness of 525 m and a diameter of 100 mm is used as a substrate for CPW printing.…”

Characterization of Silver Inkjet Overlap-printing through Cohesion and Adhesion

“…We employed the Owens-Wendt model [19] and the Girifalco [20] model to calculate the surface energy (γ s ) using the measured contact angles of DI water and CH 2 I 2 . A previously reported surface treatment [10] was performed to control the wetting nature of the hydrophobic surface as follows. First, a hydrophobic FC film was spun on a bare silicon (Si) substrate at 2000 rpm using a fluoropolymer solution composed of a mixture of Fluorad TM FC 722 and FC 40 (3M, Seoul, Korea).…”

“…Droplet merging occurs when several droplets combine to form a single droplet because of surface tension and poor wettability of the substrate surface. Line bulging occurs when the printed pattern begins to swell out; it is particularly noticeable during continuous line printing [10][11][12][13][14][15].…”

Numerical study of droplet impact and coalescence in a microline patterning process

“…Lee et al [11] studied the characteristics of printed line with control of surface energy and substrate temperature. Various surface conditions or contact angles were obtained by combining hydrophobic coating, ultraviolet/ozone treatment and substrate heating.…”