# Dry Printing of Ag-Ni Conductive Particles Using Toner-Type Printed Electronics
## 3 Results
The attractive electric field was applied between the developer reservoir and target electrode, thus the toner particle was attracted to the target electrode by an electrostatic force when the magnetic brush of the developer passed just below the target electrode pattern. During the development of the toner particles, the carrier particles remained on the developer reservoir owing to the attractive magnetic force of the magnets. In contrast, a repulsive electric field was applied between the counter electrode and magnetic brush to inhibit the adhesion of the toner particle to the exterior of the target pattern. The strength of the repulsive electric field was sufficiently weaker than that of the attractive electric field; therefore, the repulsive electric field only inhibits the adhesion of stray toner particles. Figure 6a demonstrates a photograph of the IC peripheral circuit pattern formed on a polymer film surface using our toner printing method. The applied external voltage in the target pattern was \(-100\) V, and that in the counter electrode was \(+50\) V. An external voltage of \(-100\) V was applied to attract the positively charged Ag-Ni toner particles. In contrast, an external voltage of \(+50\) V was applied to inhibit the adhesion of the stray Ag-Ni particles. Using these two external electric fields, the high-contrast printing of the fine and  
Figure 3: SEM image of the developer comprising a P-02 carrier particle and Ag–Ni composite toner particles. complicated IC peripheral circuits was achieved. Ag-Ni conductive toner particles are observed as a bright line pattern in this picture and form a circuit pattern with sufficient density. The IC peripheral circuit has a 0.20 mm resolution line pattern. This resolution is comparable to that of the current industrial electronics circuit board. Figure 6b presents a magnified view of the Ag-Ni particle pattern, indicated by the broken white rectangle in Figure 6a. The Ag-Ni particles are dispersed on the surface of the polymer film and form circuit patterns by applying an external electrostatic force. The density of the Ag-Ni toner particles in the line pattern varied by the strength of the external electrostatic force.As shown in Figures 4 and 6, a thick deposition of the toner particles in a single development is possible using this method, which is the advantage of the toner-type page printing. In contrast, dot-printing methods require a significant amount of time to create thick patterns in both the plane and thickness directions because several drops of ink are necessary for filling a thick pattern. Toner-type printing enables a wide range of controllability of the thickness in creating an electrical circuit, in which circuit patterns ranging from the \(\upmu\)m to cm scale coexist. Figure 4: (**a**) Schematic illustration of the gradation electrostatic potential applied on the PET film. (**b**) Photograph of the developed Ag–Ni toner pattern on the positive gradation-charged PET surface. (**c**) Photograph of the developed Ag–Ni toner pattern on the negative gradation-charged PET surface. To evaluate the electrical resistance of the Ag-Ni composite circuit, we performed a 4-probe electrical measurement on the compressed test piece. Figure 7a,b demonstrate the Ag and Ag-Ni composite test pieces, respectively, which were molded using oil-press equipment and cut, as shown in Figure 7a,b. Both powders were compressed and exhibited a sufficient stiffness. The Ag-compressed test piece is bright gray and partly shows a metallic luster. In contrast, the Ag-Ni composite test piece is dark gray, similar to the original particle, as shown in Figure 1b. In the Ag-Ni composite particles, Ni nanobowders on the Ag surface inhibit Ag-Ag aggregation. However, under compression, the Ni particles, which are a minority of the volume, are incorporated between compressed and deformed Ag particles. As a result, the Ag-Ni test piece has the same range of stiffness as the Ag test piece.