Inkwells for on-demand deposition rate measurement in aerosol-jet based 3D printing

Abstract

Aerosol-jet printing (AJP) is an important direct-write printing technology based on additive manufacturing methods. Numerous research groups have utilized AJP for the fabrication of electronic circuits and devices. However, there has not been any real-time or even any on-demand method for quantitatively measuring and/or setting the deposition rate of an AJ ink stream. In this paper, we present a method for measuring the deposition rate of an AJ ink stream by printing into an array of inkwells that were fabricated using photolithography and were characterized using x-ray tomography and optical profilometry. These inkwell arrays were then used to establish a set of deposition rates namely 0.0011, 0.0024, 0.0035, 0.0046 and 0.0059 mm3 s−1 that were subsequently compared with independently-measured deposition rates obtained by printing the ink stream into a weighing pan for a specified time and calculating the resulting deposition rate from the weight of the printed sample. From this comparison, it is observed that, for a human operator, the error in setting a specific deposition rate is less for inkwell fill times greater than 3 s and greater for fill times less than 3 s. This observation indicates that the average volume of an inkwell array should be at least three times the desired deposition rate (Vinkwell > 3R). It was also observed that when the diameter of the inkwell was only slightly larger than the ink stream diameter, the ink uniformly wets the sidewall of the inkwell and results in a well filled inkwell for which the point at which it is just fully filled is easily observable. Finally, the interactions of the ink with both ‘philic’ and ‘phobic’ inkwells were studied illustrating the ability to use inkwells of various materials for setting the desired deposition rates for a variety of AJ printable inks.

Conductivity and radio frequency performance data for silver nanoparticle inks deposited via aerosol jet deposition and processed under varying conditions

“…In the interest of efficiency, for each ink we printed all CPWs first, then we replaced the 100 µm nozzle with a 300 µm nozzle and printed all of the accompanying 4PP pads. To calibrate deposition rates, we employed the inkwell method as described by Gu et al [1] wherein the operator modulates the AJP flow rates until deep reactive ion etched inkwells of known and precise volumes are filled over a prescribed time interval. Key parameters associated with printing features using each of the three inks are shown in Table 7 .…”

The Effect of Droplet Sizes on Overspray in Aerosol‐Jet Printing

“…Figure a provides an example of AJP features where the OS is clearly visible and seen to cover the area between printed traces. For a given CGF, changes in ShGF can affect both the ink stream width and the OS, as demonstrated in Figure b: for four traces that were printed with the same deposition rate and print speed but different ShGFs. Notice that while the ink stream width decreases with increasing ShGF, we witness first a decrease and then an increase of the OS with an increase of the ShGF rate.…”

Direct‐Write Printed, Solid‐Core Solenoid Inductors with Commercially Relevant Inductances

“…The reasons for selecting NEA121 ink over other polymer inks are summarized in the Supporting Information. Ink stream deposition rates of 0.003 mm 3 s −1 for the DOWA ink and 0.006 mm 3 s −1 for the NEA121 ink were established using the previously published inkwell method . All winding traces were printed using an ink steam width of 100 µm, a print speed of 3 mm s −1 and a build plate temperature of 50 °C.…”

“…Toward this end, in this paper, we describe a novel direct‐write 3D printing method for fabricating solid‐core (polymer‐core, iron‐core, and ferrite‐core) inductors that demonstrate inductance values ranging from µH to mH and operate at frequency ranges of several kHz to MHz. We employ aerosol jet 3D printing (AJP), with a precisely controlled aerosol ink‐stream deposition rate for the fabrication. AJP is used to print both the polymer core (using an ultraviolet curable polymer ink) and the conducting windings (using a Ag nanoparticle ink) of the solid‐core inductors.…”