Aerosol Jet Direct Writing Polymer-Thick-Film Resistors for Printed Electronics

Abstract

To improve performance and reduce size of printed-circuit board (PCB) in electronics industry, embedding discrete components within a board substrate has been an effective approach by reducing solder joints and their associated impedance mismatching, inductive reactance, etc. With its unique capabilities for non-contact precision material deposition, the Aerosol Jet® direct-write technology has been enabling additive manufacturing of fine-feature electronics conformally onto flexible substrates of complicated shapes. The CAD/CAM controlled relative motions between substrate and print head allows convenient adjustment of the pattern and pile height of deposited material at a given ink volumetric deposition rate. To date in the printed electronics industry, additively printing embedded polymer-thick-film (PTF) resistors has mostly been done with screen printing using carbon-based paste inks. Here we demonstrate results of Aerosol Jet® printed PTF resistors of resistance values ranging from ~50 W to > 1 kW, adjustable (among several variable parameters) by the number of stacked layers (or print passes with each pass depositing a fixed amount of ink) between contact pads of around 1 mm apart with footprint line typically < 0.3 mm. In principle, any ink material that can be atomized into fine droplets of 1 to 5 microns can be printed with the Aerosol Jet® system. However, the print quality such as line edge cleanliness can significantly influenced by ink rheology which involves solvent volatility, solids loading, and so on. Our atomizable carbon ink was made by simply diluting a screen printing paste with a compatible solvent of reasonable volatility, which can be cured at temperatures below 200 oC. We show that Aerosol Jet® printed overlapping lines can be stacked to large pile height (to reduce the resistance value) without significant increase of line width, which enables fabricating embedded resistors with adjustable resistance values in a limited footprint space.

Fabrication of RC filters from a single printed Zn layer by reactive inkjet printing

“…A wide range of resistances can be achieved by tuning the conductor/filler concentration [17] or by varying the geometry of the printed resistor (i.e. length, width, and thickness) [18]. Alternatively, resistance can be tuned via adjustments in the printing or treatment processes.…”

Hybrid Process Chain for the Integration of Direct Ink Writing and Polymer Injection Molding

“…The increasing industrial adoption of AM technologies has been shifting the focus from prototyping to direct integration with established processing technologies and applications. In particular, direct-write additive manufacturing has shown promise in a variety of applications ranging from radio frequency (RF) to sensing and even microfluidic integration [1][2][3][4][5][6][7][8][9][10]. Among AM technologies, direct-write micro-dispensing using silver conductive inks is one of the most common methods used to create printed electronics [11,12].…”