Charged Molten Metal Droplet Deposition as a Direct Write Technology

2000 ◽  
Vol 624 ◽  
Author(s):  
M. Orme ◽  
J. Courter ◽  
Q. Liu ◽  
J. Zhu ◽  
R. Smith
Keyword(s):  
Molten Metal ◽  
High Speed ◽  
Droplet Diameter ◽  
Metal Droplet ◽  
Circuit Board ◽  
Charged Droplet ◽  
Direct Write ◽  
Direct Writing ◽  
Drop On Demand ◽  
Metal Droplets

ABSTRACTThe formation of highly uniform charged molten metal droplets from capillary stream breakup has recently attracted significant industrial and academic interest for applications requiring high-speed and high-precision deposition of molten metal droplets such as direct write technologies. Exploitation of the high droplet production rates intrinsic to the phenomenon of capillary stream break-up and the unparalleled uniformity of droplet sizes and speeds attained with proper applied forcing to the capillary stream make many new applications related to the manufacture of electronic packages, circuit board printing and rapid prototyping of structural components feasible. Recent research results have increased the stream stability with novel acoustic excitation methods and enable ultra-precise charged droplet deflection. Unlike other modes of droplet generation such as Drop-on-Demand, droplets can be generated at rates typically on the order of 10,000 to 20,000 droplets per second (depending on droplet diameter and stream speed) and can be electrostatically charged and deflected onto a substrate with a measured accuracy of ±12.5 µm. Droplets are charged on a drop-to-drop basis, enabling the direct writing of fine details at high speed. New results are presented in which fine detailed patterns are “printed” with individual molten metal solder balls, and issues relevant to the attainment of high quality printed artifacts are investigated.

Photo-Polymerized Acrylic Waveguides for Optical Interconnects

1991 ◽  
Vol 228 ◽  
Author(s):  
Robert R. Krchnavek ◽  
Gail R. Lalk ◽  
Robert Denton
Keyword(s):  
High Speed ◽  
Optical Channel ◽  
Direct Write ◽  
Material System ◽  
Direct Writing ◽  
Laser Technique ◽  
Electronic Board ◽  
Channel Waveguides ◽  
Optical Applications ◽  
Urethane Dimethacrylate

ABSTRACTWe have fabricated acrylic based optical channel waveguides using proximity photolithography as well as laser direct writing. The cladding layer is a photosensitive aliphatic urethane dimethacrylate and the guiding layer is a photosensitive aromatic acrylated epoxy. This material system provides good adhesion to a variety of substrate materials. Since both the guiding and cladding layers are applied, these materials can be employed in several electrical/optical applications including multi-chip modules using Si, SiO2, and polyimide as well as high speed electronic board technologies using teflon based substrates.Loss measurements show a guide loss of less than 0.08 dB/cm for multi-mode waveguides fabricated using the direct write laser technique. Lithographically defined guides have a loss of 0.3 dB/cm for similar size waveguides.

Diagnostic Development for Control of Wire-Arc Spraying

1997 ◽  
Author(s):  
J. Sheard ◽  
J. Heberlein ◽  
K. Stelson ◽  
E. Pfender
Keyword(s):  
Molten Metal ◽  
High Speed ◽  
Metal Droplet ◽  
Arc Spraying ◽  
Voltage Fluctuations ◽  
Arc Voltage ◽  
Spray Process ◽  
Arc Spray ◽  
Labview Software ◽  
The Wire

Abstract This research has focused on characterization of the wire arc spray process with the goal of achieving improved process controls. Arc voltage and current traces have been analyzed on-line using an oscilloscope and a personal computer with LabView software. The characteristic features of the arc voltage fluctuations are correlated with the molten metal droplet formation process using a high speed Laser Strobe video system operating in synchronization with the oscilloscope trigger. Voltage minima occur when larger globules of molten metal leave the wire tip. Analysis of the voltage fluctuations indicate that they are neither random nor periodic, and that they can be described based on chaos theory. This approach may be used for achieving a further understanding of the dynamic nature of the process, and for the development of control algorithms.

Gap Adjustable Molten Metal DoD Inkjet System With Cone-Shaped Piston Head

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Taik-Min Lee ◽  
Tae Goo Kang ◽  
Jeong Soon Yang ◽  
Jeongdai Jo ◽  
Kwang-Young Kim ◽  
...  
Keyword(s):  
Molten Metal ◽  
Performance Test ◽  
Printed Electronics ◽  
Droplet Diameter ◽  
Point Of View ◽  
Chamber Pressure ◽  
Piston Head ◽  
Drop On Demand ◽  
Wide Range ◽  
Molten Metal Drop

In this paper, we present the design, fabrication, and performance test of a gap adjustable molten metal drop-on-demand (DoD) inkjet system with a cone-shaped piston head, which can eject a droplet of lead-free molten solder at high temperature. The gap adjustable mechanism with the cone-shaped piston head is proposed for optimizing the gap distance between the chamber wall and piston head. The droplet diameter and velocity can be controlled in a wide range by moving the initial gap distance and minutely by controlling the chamber pressure. Stability and satellite can be partly adjusted by controlling the initial gap distance and the chamber pressure, respectively. The working temperature is improved by locating the piezoelectric actuator at the outside of the furnace and by inserting the insulation block between the print head and the actuator. From a practical point of view, the molten metal DoD inkjet system presents a simple structure for easily interchangeable nozzle parts, even though the nozzle is choked. The gap adjustable molten metal DoD inkjet system with cone-shaped piston head has great potential as a manufacturing tool for direct printing a viscous material at various temperatures. It is expected to be applicable in many industrial fields including semiconductor packaging, electrode bonding, printed electronics, information, and display industry.

Effect of Substrate Temperature on Splashing of Molten Metal Droplets

Volume 1 ◽  
2004 ◽  
Author(s):  
Rajeev Dhiman ◽  
Sanjeev Chandra
Keyword(s):  
Substrate Temperature ◽  
Molten Metal ◽  
High Impact ◽  
Small Satellite ◽  
Solid Layer ◽  
Uniform Size ◽  
On Demand ◽  
Drop On Demand ◽  
Splat Thickness ◽  
Metal Droplets

The effect of substrate temperature on the splashing of molten metal droplets was studied experimentally. Uniform-size molten tin droplets (550 μm diameter) were produced using a drop-on-demand generator. To achieve high impact velocities substrates were mounted on the rim of a rotating flywheel and heated using cartridge heaters to vary substrate temperature. Droplets hitting a smooth cold substrate splashed extensively producing many small satellite droplets and leaving on the surface a small, irregular splat with many fingers projecting from its periphery. Droplets hitting a hot substrate did not splash but spread out to form a smooth disc. A new splashing criterion was developed to calculate the substrate temperature at which this transition occurred. It assumes splashing to occur when the solid layer produced as a result of droplet solidification grows equal to the splat thickness and obstructs the spreading liquid.

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

2021 ◽  
Vol 34 (1) ◽  
pp. 24-31
Author(s):  
James Feng ◽  
Anthony Loveland ◽  
Michael Renn
Keyword(s):  
Thick Film ◽  
Screen Printing ◽  
Printed Circuit Board ◽  
Printed Electronics ◽  
Electronics Industry ◽  
Circuit Board ◽  
Print Quality ◽  
Direct Write ◽  
Direct Writing ◽  
Fixed Amount

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.

scholarly journals In-situ monitoring for liquid metal jetting using a millimeter-wave impedance diagnostic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tammy Chang ◽  
Saptarshi Mukherjee ◽  
Nicholas N. Watkins ◽  
David M. Stobbe ◽  
Owen Mays ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Millimeter Wave ◽  
Manufacturing Systems ◽  
Wave Impedance ◽  
In Situ Monitoring ◽  
Full Wave ◽  
Drop On Demand ◽  
The Time Domain ◽  
Metal Droplets

AbstractThis article presents a millimeter-wave diagnostic for the in-situ monitoring of liquid metal jetting additive manufacturing systems. The diagnostic leverages a T-junction waveguide device to monitor impedance changes due to jetted metal droplets in real time. An analytical formulation for the time-domain T-junction operation is presented and supported with a quasi-static full-wave electromagnetic simulation model. The approach is evaluated experimentally with metallic spheres of known diameters ranging from 0.79 to 3.18 mm. It is then demonstrated in a custom drop-on-demand liquid metal jetting system where effective droplet diameters ranging from 0.8 to 1.6 mm are detected. Experimental results demonstrate that this approach can provide information about droplet size, timing, and motion by monitoring a single parameter, the reflection coefficient amplitude at the input port. These results show the promise of the impedance diagnostic as a reliable in-situ characterization method for metal droplets in an advanced manufacturing system.

A Study on Evolution of Splat Radius and Temperature in Thermal Spray Process

2018 ◽  
Author(s):  
Manpreet Dash ◽  
Sangharsh Kumar ◽  
Partha Pratim Bandyopadhyay ◽  
Anandaroop Bhattacharya
Keyword(s):  
Heat Transfer ◽  
Thermal Spray ◽  
Molten Metal ◽  
Spray Deposition ◽  
Substrate Surface ◽  
Metal Droplet ◽  
Droplet Impingement ◽  
Impact Process ◽  
The Impact ◽  
Maximum Spreading

The impact process of a molten metal droplet impinging on a solid substrate surface is encountered in several technological applications such as ink-jet printing, spray cooling, coating processes, spray deposition of metal alloys, thermal spray coatings, manufacturing processes and fabrication and in industrial applications concerning thermal spray processes. Deposition of a molten material or metal in form of a droplet on a substrate surface by propelling it towards it forms the core of the spraying process. During the impact process, the molten metal droplet spreads radially and simultaneously starts losing heat due to heat transfer to the substrate surface. The associated heat transfer influences impingement behavior. The physics of droplet impingement is not only related to the fluid dynamics, but also to the respective interfacial properties of solid and liquid. For most applications, maximum spreading diameter of the splat is considered to be an important factor for droplet impingement on solid surfaces. In the present study, we have developed a model for droplet impingement based on energy conservation principle to predict the maximum spreading radius and the radius as a function of time. Further, we have used the radius as a function of time in the heat transfer equations and to study the evolution of splat-temperature and predict the spreading factor and the spreading time and mathematically correlate them to the spraying parameters and material properties.

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