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August, 2018


Aerosol Jet Printing: An Evolutionary Dispensing Solution By Mike O’Reilly, Director — Aerosol Jet Products, Optomec, Inc.


applied to consumer electronic device performance as well. While the number of components that drive the electronics packaging and assembly industry will not double every two years, product miniaturization, coupled with increased function- ality continues to push manufacturing solutions to meet greater production demands. According to iNEMI, it is expected that by


M


2023, component interconnects will be driven down to less than 0.8 mil (20 µm) line-to-line pitch- es. Connections on actual packages will need to keep pace, putting an increased burden on already-taxed manufacturing equipment and processes. Couple this with ever-evolving requirements


for more communications capabilities built into smart devices and the gap between leading-edge and mainstream product packaging and assembly is rapidly closing. Device failures caused by radio frequency interference (RFI) or electromagnetic radiation or electromagnetic interference (EMI) are increasing, due to the growing number of prod- ucts that contain sensitive electronic components. The smaller size and faster operating speeds of these components make it more difficult to manage the RFI/EMI pollution they create. Manufacturing methods, such as physical


vapor deposition (PVD) and spray coating, are rap- idly replacing traditional mechanical shielding enclosures in production today. However, PVD is expensive and spray coating is not a precise process with deposition thicknesses and edge coat- ing varying greatly As component-to-component spacing contin-


ues to shrink, in some cases to less than 4 mil (100 µm), the coating of chip edges is more challenging. Critical circuity that must be accessible needs to be masked off and secondary steps are then required to expose it.


New Type of Microdispensing These challenges are being driven by the


demand for increased product functionality and overall package size reduction. Production-scale screen printing, time-pressure and jet dispensing, along with other production-proven tools, are not going away anytime soon. In many instances these manufacturing tools are being pushed to their physical limits in terms of feature sizes and flexi- bility. Product developers are requiring that their manufacturers implement flexible production processes to meet mass customization require- ments. Flexible processes require smart, digitally driven production solutions. Greater manufactur-


oore’s Law, the concept that the number of transistors in a semiconductor device dou- bles roughly every two years, can be


produce high-density crossover and multilayer cir- cuitry. The Aerosol Jet printer is capable of pro- ducing precision conformal coatings on nonplanar surfaces, enabling chip- and board-level RFI/EMI shielding.


Larger nozzles enable single-pass printing of


coatings that measure from millimeters in width, while maintaining uniform layer thickness from 100 nanometers to tens of microns. The Aerosol Jet’s fine-feature printing and edge coating of com- plex packages enables selective exposure to con- tacts and ground planes. Packaged with a produc- tion-proven dispense platform solution, the Aerosol Jet printer can be integrated directly into dispensing production lines.


Aerosol Jet Process Aerosol Jet is a direct-write printing solution


that uses nitrogen gas (NI-IND) for aerodynamic focusing of aerosolized droplets to precisely deposit functional materials onto a substrate. The process begins by aerosolizing a liquid into small droplets with diameters between 0.08 and 0.2 mil (2 and 5 µm), or approximately 10 femtoliters. These droplets are then passed through a


Optomec’s Aerosol Jet HD printer.


ing flexibility requires new digital tools, materials and processes integrated into existing production lines.


Optomec’s Aerosol Jet® printer (dispenser) is


one of a new class of microdispensing products that was developed to be highly versatile. With its abil- ity to print fine features, and an array of printable materials, the printer can produce high-resolution adhesive pads with features as small as 1 mil (25 µm).


This supports both conductive and noncon-


ductive attach of today’s smallest dice and compo- nents, without the need for manual rework, increasing overall throughput and eliminating wasteful, end-of-line cleaning steps. In addition to conductive materials, the Aerosol Jet printer is capable of high-resolution printing of a wide range of common nonconductive materials. Applications include MEMS bonding, seals,


local passivation, and insulative overcoats. When coupled with conductor printing, the printer can


The Aerosol Jet printer is capable of


dispensing materials for EMI/RFI shielding. Aerosol Jet printing differs from other dis-


pensers, such as traditional time-pressure or jet dispensers, which print on a drop-by-drop basis. With its continuous aerosolized stream of material


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deposition head where they are focused into a col- limated beam through the use of a secondary stream of nitrogen gas, referred to as a sheath, which surrounds the material as it passes through the nozzle. This focusing function enables the printing of features that range from less than 0.8 mil (20 µm) in diameter up to millimeters in size. The aerosol beam is emitted from the deposition head at a velocity of approximately 164 ft/s (50 m/s) and travels ballistically to where the droplets impinge on the substrate.


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