Use of a 6-axis robot and ink piezo-jetting to print conductive paths on 3D objects. Printed circuit geometry, and conductivity predictive model

Optimization of trajectory processing algorithms to print 3D circuit boards using piezo ink jet and 6-axis robots

“…Cell setup. A inhouse designed robotic cell [23], composed of a 6-axis robot (Staubli TX2 60, 670 mm range and 0.02 mm repeatability) equipped with a high-speed laser profilometer (Keyence, LJ-V7080/LJ-X8000A) and a piezo jetting dispensing valve (Vermes MDV 3200A) mounting a 0.1 mm nozzle was wired and mounted on a low vibration bench (AlpRobotic, France). The laser profilometer was used to scan the surface of 3D objects at speeds of 40 or 50 mm/s and sampling frequencies of 200 and 1000 Hz, corresponding to sampling periods of 200 and 50 µm, respectively.…”

“…In this study the tappet-rising, -opening and -falling time had constant values (of 0.5, 2 and 0.2 ms, respectively), whereas, the delay time between each dispensing cycle was varied between 0.1 and 1000 ms in order to adapt the overall jetting frequency to the printing speed (i.e. the jetting valve TCP speed) and the desired path width using a semi-empirical model developed in a previous study [23]. The protocol to generate an accurate and smooth printhead trajectory and to synchronize the ink jetting frequency with the printing speed was based on four sequential operations: i) Meshing and smoothing points obtained with the laser profilometer.…”

“…Since the complex kinematic and the presence of singularities does not allow poly articulated robots to keep a constant speed along 3D paths, the TCP speed was retrieved during a blank run along the printing trajectory. According to a semi-empirical model described in a previous work [23], the average speed (𝑉 ), the diameter of individual ink drops ejected by the printhead (0 = 0.280 mm in the tested conditions) and the target line width (w) were used to calculate the jetting frequency (𝐹 ) and the drop number (𝑛 ) necessary to print the path using the equations:…”

“…The direct printing of conductive and dielectric inks by piezo jetting [20], ink jet and aerosol spray [21] or needle dispensing [22] appear as a viable alternative to LDS. Indeed, recent studies demonstrated that the integration of piezo or pneumatic jetting printheads on a 6-axis robot can be effectively used to print silver tracks on a 3D paper substrate [23], RF antennas on PC-ABS objects [24], [25] and large-scale composites [26]. Whereas, pneumatic needle dispensing has been used to print conductive tracks during the 3D printing of a PLA helicoidal structure on a double robot bench [27].…”