This article reports on a number of experiments that have been performed, which show that the resistance of silver lines formed in channels is lower than silver lines that have been formed on unstructured surfaces. Channels were formed either by being cut into polyimide (Kapton) using a laser or by hot embossing a polycarbonate blend (Bayfol). An ink jet printer was used to dispense silver-containing ink over the embossed channels, the laser cut channels and over unstructured Kapton and Bayfol to allow comparison. Two types of silver-containing ink were used, one was a nanoparticle (NP) ink and the other was a metallo-organic decomposition (MOD) ink. For the NP ink, a decrease in resistance was seen for the lines formed in hot embossed channels. For the MOD ink, the resistance decrease was seen for lines formed in both the embossed and the laser cut channels. (C) 2011 Society for Imaging Science and Technology [DOI: 10.2352/J.ImagingSci.Technol.2011.55.4.040302]

The fabrication of a poly(3,4-ethylenedioxythiophene) (PEDOT) pattern is demonstrated. As template, an n-octadecyltrichlorosilane (OTS) monolayer self-assembled on indium tin oxide (ITO) was structured by UV–ozone photolithography, resulting in an ITO–OTS patterned surface. The conducting properties of the ITO were utilized for the selective electropolymerization of 3,4-ethylenedioxythiophene (EDOT), whereby the electropolymerization was inhibited by the insulating OTS. Differently sized PEDOT–OTS patterns were obtained. The electronic properties of the patterns were finally evaluated in a test OLED device.

Microwave flash sintering of inkjet printed colloidal silver dispersions on thin polymer substrates was studied as a function of the antenna area and initial resistance. The presence of conductive antennae promotes nanoparticle sintering in pre-dried ink lines (see figure). For dried nanoparticle inks connected to antennae, sintering times of 1 s are sufficient: to obtain pronounced nanoparticle sintering and conductivities between 10 and 34% compared to bulk silver.

A one-step process to fabricate conductive features on flexible polymer substrates by inkjet printing an organometallic silver ink directly onto a substrate that is heated to 130 degrees C is presented. This process led to the immediate sintering of the printed features. The samples were left for 5 min at elevated temperature, which resulted in conductive silver features with a resistivity of eight times the bulk silver value. The combination of this ink and the simultaneous printing/sintering process opens up routes for the direct fabrication of conductive features on common polymer substrates that could be applied, for example, in roll-to-roll production of flexible microelectronic systems.

An alternative and selective sintering method for the fabrication of conductive silver tracks on common polymer substrates is presented, by exposure to low-pressure argon plasma. Inkjet printing has been used to pattern a silver nanoparticle ink. This resulted in conductive features with a resistivity less than one order of magnitude higher than the bulk value of silver without affecting the polymer substrate. This process may be employed in the production of conductive features with low material usage on common polymer substrates in, for example, printed electronics.

Hot‐embossed features are prepared by pushing customized and standard silicon calibration gratings, known as masters, into either polystyrene or polycarbonate, which are kept above their glass transition temperatures. droplet of a silver nanoparticle ink is then dispensed over one of these as‐formed grooves using an inkjet printer. The ink fills the grooves as a consequence of capillary forces and is observed to form tracks with a uniform width. The tracks are described as ‘invisible’ on account of having widths ranging from 5 to 15 µm. Wider tracks can be produced by dispensing more droplets and tracks with different morphologies can be produced by using different masters. Several as‐prepared features are thermally treated to produce conductive silver tracks. The conductivity of the tracks is found to be ∼20% that of bulk silver.

The deposition behaviour of uniformly sized silica particles in drying aqueous droplets has been investigated for a range of particle sizes, 0.33, 1, 3 and 5 μm, in order to gain an improved understanding of the coffee drop effect. The droplets were produced by inkjet printing, which allowed multiple droplets of similar volume to be studied. Our observations show that particle size and the contact angle formed by the solvent droplet with the substrate determine how close to the boundary a particle is deposited. After drying, it was found that if the contact angle was less than 90°, smaller particles were located closer to the original droplet's periphery than larger particles in similar sized droplets. This deposition of particles can be explained by the wedge shape of the drying droplet's edge, which physically limits the movement of particles towards the droplet's periphery. In this paper we show that the size of a suspended particle influences the final dried morphology of a printed feature.

In this contribution the curing behavior and conductivity development of several commercially available silver inks is discussed. In addition, the preparation and characterization of a silver particle ink that shows a curing temperature as low as 80 degrees C is described. Good to excellent conductivity values of 5 to 56% of bulk silver have been reached by using a very small amount of organic additives without any strong adsorbing groups such as amines, amides or mercapto groups. This low curing temperature opens new routes to produce conductive features on polymeric foils that have a low T-g, like PET. Furthermore, the temperature stability of silver tracks, prepared by inkjet printing different colloidal silver suspensions, was investigated. Hereto, the resistance was on-line measured during heating of the silver tracks, from room temperature to 650 degrees C.

Using depth-sensing indentation, the elastic modulus E of a diblock copoly(2-oxazoline) library was investigated in order to determine structure-property relationships. The adopted experimental procedure, dropcasting of the copolymer materials and determining the elastic modulus by depth-sensing indentation, was compatible with high-throughput experimentation. The elastic modulus of the investigated materials depended strongly on the side-group. Materials containing poly(nonyloxazoline) exhibited a lower modulus than materials without any poly(nonyloxazoline) block as poly(nonyloxazoline) was at room temperature above its glass-transition temperature Tg, while the other homopolymers in this study were glassy at room temperature. The elastic modulus also depended on the relative humidity (RH) of the testing environment; the stiffness of ethyloxazoline and methyloxazoline decreased significantly due to water absorption from the air. At lower RH, hydrogen bonding or polar interactions among the polymer chains resulted in a surprisingly high modulus for the poly(methyloxazoline). In addition, as anticipated, the elastic moduli of AB diblock copolymers were bounded by those of the A and B homopolymers, both at high and at low RH. The presented results indicate how, and to what extent, for these materials the E (and the change in E) at a given (change in) humidity can be adjusted by tailoring the composition.