Effect of Sintering Time and Sintering Temperature on the Mechanical and Electrical Properties of Aerosol-Jet Additively Printed Electronics

Aerosol‐Jet Printed Sensors for Environmental, Safety, and Health Monitoring: A Review

“…[ 32 ] While the droplets are in transport, some collide with the inner walls of the tubing and thus never reach the deposition head. [ 32 ] Large and small droplets that in fact reach the deposition head are subject to gravitational settling and diffusion, respectively, and these mechanisms affect the output of atomized ink. Once the droplets reach the deposition head, the focused stream is accelerated through a nozzle with an internal diameter of 50–300 µm and length of 20 mm.…”

“…In addition to processing parameters such as sheath flow rate, standoff height, platen temperature, and ink flow rate that affect the feature size, electrical properties, and mechanical reliability of AJP‐produced printed lines, print quality, and hence device performance is also affected by sintering time and temperature of nanoparticle‐based inks (Figure 3c). [ 32 ] As described above, thermal sintering of conductive metallic inks, the conventional selection for sensing electrode designs, is required for the removal of excess materials during the sensor fabrication process and ensures the printed line is highly conductive and continuous. Following deposition of lines onto the relevant substrate, inks are cured and/or sintered based on the respective properties of the substrate and material type (≈110–300 °C for silver nanoparticle‐based inks [ 85 ] ) with profiles controlled through specification of the sintering temperature and time.…”

“…Upon sintering, the agglomeration of uniformly stacked metallic nanoparticles then partially melts to form a cohesive solid, the process of which affects electrical performance such as resultant line resistivity and resistance as well as mechanical performance such as elastic modulus and shear strength of the line. [ 32 ] However, it has been demonstrated that lowering the sintering time can decrease resistance due to attenuation of microcracks in the printed lines. [ 32 ] Likewise, resistivity is increased upon lowering sintering temperatures due to increases in porosity caused by inferior line melting.…”

“…[ 32 ] However, it has been demonstrated that lowering the sintering time can decrease resistance due to attenuation of microcracks in the printed lines. [ 32 ] Likewise, resistivity is increased upon lowering sintering temperatures due to increases in porosity caused by inferior line melting. While this thermal step does not present a significant issue in applying direct‐write techniques to metal [ 111 ] or temperature‐resistant polymer (i.e., polyimide [ 112 ] ) substrates, it poses challenges for materials with glass transition temperatures ( T g ) or melting points ( T m ) near or below the ink's required sintering temperature (e.g., ≈110–300 °C for silver nanoparticle‐based inks [ 85 ] ).…”

“…This distribution of droplet sizes accordingly results in a line that has a dense core region surrounded by a diffuse area of overspray. [ 32 ] Overspray as an inherent feature of AJP is defined as deposition of the smallest aerosol droplets outside the intended pattern. High resistivity usually results from the residual chemicals (i.e., surfactants, stabilizers) added to the ink formulation.…”