Aerosol-based print cartridges and their use in devices and methods of use thereof - Patents.com

Abstract

An aerosol-based printing device is provided that can generate an aerosol stream at a constant rate, deposit a constant material on a substrate, and provide high-definition, high-resolution traces. The aerosol-based printing device generates, transports, and delivers the aerosol stream at a constant rate for a constant operating period of at least 8 hours, and in other cases, more than 24 hours. By suppressing bulging and necking of the deposited trace, excellent linewidth tolerances are achieved, and maintaining such tolerances over time enables both the deposition of complex traces and the consistent production of replica products that maintain tolerances over production runs. Eliminating fluid accumulation in aerosol and gas delivery conduits eliminates the need for purge or cleaning cycles, allowing for uninterrupted operation for at least 24 hours.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 905,571, filed September 25, 2019, which is incorporated herein by reference.

[0002] The present invention relates generally to a device for depositing high density, high resolution traces on a surface using aerosol printing, and in particular aerosol-based printing. [Background technology]

[0003] Direct-write printing, defined as the maskless printing of inconspicuous patterns onto a substrate in a one-step process, offers many advantages over traditional printing techniques such as lithography and chemical and physical vapor deposition. Indeed, direct-write processes, such as aerosol-based printing, are much cheaper to establish and maintain and offer greater flexibility than traditional techniques.

[0004] Typically, aerodynamic lenses are used in aerosol-based printing. The use of aerodynamic lenses to focus an aerosol stream is well known as described by Peng Liu, Paul J. Ziemann, David B. Kittelson, and Peter H. McMurry, Generating Particle Beams of Controlled Dimensions and Divergence: I. Theory of Particle Motion in Aerodynamic Lenses and Nozzle Expansions, Aerosol Science and Technology, 22:3, 293-313 (1995). An aerodynamic lens is defined as a flow configuration in which a stream passing through a cylindrical channel with diameter D passes through an orifice of diameter d, contracts once upstream of the orifice, and then expands immediately downstream of the orifice. The contraction of the aerosol stream occurs as the flow approaches and passes the orifice. The gas then expands as the flow propagates downstream to a wider cross-sectional area. The flow through the orifice forces the particles towards the flow axis, so that the aerosol stream becomes narrow and collimated, providing the functional attributes of the lens. Aerosol streams collimated by aerodynamic lens systems have been designed for use in many areas, such as pharmaceutical aerosol delivery and additive manufacturing. In a typical aerodynamic lens system, the aerosol stream is tightly confined around the axis of the flow cell by passing the particle distribution through a series of axisymmetric contractions and expansions. Each section of the lens system, consisting of the flow channel and orifice, is defined as a stage. Liu presented a method and apparatus for focusing submicron particles using an aerodynamic lens system. Di Fonzo et al. and Dong et al. designed lens systems to focus particles with diameters in the range of 10-100 nanometers and 10-200 nanometers, respectively.Di Fonzo, F., Gidwani, A., Fan, MH, Neumann, D., Iordanoglou, DI, Heberlein, JVR, McMurry, PH, Girshick, SL, Tymiak, N., Gerberich, WW, and Rao, NP, “Focused nanoparticle-beam deposition of patterned microstructures,”Appl.Phys.Lett.77(6),910(2000). Dong, Y., Bapat, A., S. Hilchie, U. Kortshagen and S. Campbell, “Generation of nano-sized free standing single crystal silicon particles”, Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 22, 1923 (2004).

[0005] Wang designed a lens system to focus particles in the 3-30 nanometer range. Lee reported a method to focus micron-sized particles at atmospheric pressure using a single lens system composed of multiple stages. Lee, JW et al.”Inertial focusing of particles with an aerodynamic lens in the atmospheric pressure range”, Aerosol Science 34(2003)211-224.

[0006] In U.S. Patent No. 6,348,687, Brockmann discloses an apparatus for producing a collimated aerosol beam of particles with diameters between 1 and 100 microns. Brockmann's aerodynamic lens system uses a series of fixed lenses and an annular sheath gas that surrounds a carrier gas packed with particles. Brockmann's system is used to focus 15 micron aluminum particles to 800 microns in diameter, typically using the same aerosol and sheath gas flow rates. In U.S. Patent No. 7,652,247, Lee discloses an aerodynamic lens system for focusing nanoparticles with diameters between 5 and 50 nanometers in air. In U.S. Patent No. 8,119,977, Lee discloses a multi-stage, multi-orifice aerodynamic lens for focusing a range of particle sizes covering two orders of magnitude, from 30 to 3000 nanometers. In U.S. Patent No. 6,924,004, Rao discloses a method and apparatus for depositing films and coatings from nanoparticle streams focused using an aerodynamic lens system. Rao's device uses high velocity impaction to deposit nanoparticles onto a substrate. A method for separating particles from a gas flow using successive expansions and compressions of the flow created by an aerodynamic lens is discussed by Novosselov in U.S. Patent No. 8,561,486.

[0007] Hydrodynamic focusing using sheath gas is generally achieved by propagating an annular sheath / aerosol flow through successively converging nozzles using different sheath and aerosol gas flow rates. The degree of focusing is proportional to the ratio of the gas flows. In U.S. Pat. No. 7,108,894, Renn discloses a method of particle focusing using a coaxial sheath gas flow surrounding an aerosol-laden carrier gas. The combined flow is then propagated through a converging nozzle. Renn teaches that in the operating range of a flow system using sheath aerosol streams and a single converging nozzle, the diameter of the focused beam is a strong function of the ratio of sheath to aerosol gas flow rates.

[0008] The focusing of a stream of aerosol particles using a system of aerodynamic lenses was first reported by Liu, as mentioned above. Liu's system was used to narrow and collimate a beam of spherical particles with diameters of approximately 25-250 nanometers. Liu used a three- to five-stage lens system, with an emphasis on achieving low pressure loss across each lens. After Liu's work, numerous experimental and theoretical studies have been carried out, considering the aerodynamic effects of single and multi-orifice lens configurations.

[0009] A number of researchers have reported studies of aerodynamic focusing of aerosol streams using fixed multi-stage lens systems (Lee, Brockmann, and Liu). Lee discloses an aerodynamic lens for focusing nanoparticles with diameters ranging from 30 to 3000 nanometers. Brockmann describes a multi-stage lens system for focusing large solid particles. The Brockmann device further uses an annularly flowing sheath gas to prevent particles from impacting the orifice surface. The Brockmann device propagates the sheath gas flow through the entire multi-stage lens system. Liu disclosed an apparatus for focusing nanoparticles using a three-stage aerodynamic system.

[0010] Prior art attempts at aerosol-based printing have met with limited success, in part due to the frequent requirement for servicing. As a result, reliable manufacturing-scale reproduction has been hindered by throughput limitations and a lack of maintaining reproducible tolerances. One cause of the need for servicing has been the accumulation of fluid along the flow paths, particularly at the gas input, aerosol output, and a combination of both.

[0011] Thus, there is a need for an aerosol-based printing apparatus that inhibits the accumulation of fluids in the gas and aerosol transport conduits. Additionally, there is a need for a method of operating an aerosol-based printing apparatus that can provide a stable aerosol stream at a constant material deposition rate to a substrate to provide high definition, high resolution traces for eight or more continuous hours without servicing. Summary of the Invention

[0012] An aerosol printing inkjet cartridge is provided. The cartridge includes a housing, a vial adapted to store an aerosol ink, and at least one internal baffle extending from an inner wall of the housing and in fluid communication with the removable vial to define an aerosol chamber. A gas inlet tube is adapted to provide an inlet gas to or adjacent the aerosol chamber, and an outlet channel through which the aerosol ink is output as particles is in fluid communication with the aerosol chamber. The at least one baffle is a single baffle and has a shape that is planar, arcuate, split cylindrical, acute angled, S-shaped, or Y-shaped.

[0013] An apparatus is provided for printing discrete, high-resolution, high-density features on a surface using an aerosol stream utilizing an aerosol printing inkjet cartridge as described above. The apparatus has an atomizer positioned to atomize the aerosol ink, a flow cell including at least one aerodynamic lens and one converging fluid dispensing nozzle having a sheath gas flow therearound, and a non-contact, pneumatic shutter assembly positioned to selectively interfere with the nozzle stream. The atomizer has variable excitation, continuous excitation, or pulsed excitation.

[0014] A method is provided for printing traces on a substrate using the apparatus described above. The method includes providing an aerosol ink in a vial, introducing an aerosol transport gas into the cartridge through a gas inlet tube or gas inlet port, and atomizing the aerosol ink using an ultrasonic transducer in the atomizer to create an aerosol-laden gas. A sheath gas is then introduced into the atomizer through a port to form an annular coaxial flow with the aerosol-laden gas to create a combined flow, passing the combined flow through a flow cell, and outputting the aerosol-laden gas from an output port at a constant flow rate. The method allows for continuous unassisted printing for 8 to 24 hours. [Brief description of the drawings]

[0015] The present invention is described in more detail with reference to the following drawings, which are intended to illustrate certain aspects of the invention and should not be construed as limitations on the practice of the invention. [Figure 1A] FIG. 1A is a plan view of a printhead of the present invention including a replaceable ink cartridge, an atomizer base, a cold plate, a flow cell, and a fluid dispensing tip. [Figure 1B] FIG. 1B shows a cross-sectional view of the ink cartridge of FIG. 1A with a single internal baffle of cylindrical shape and an aerosol gas tube. [Figure 2A] FIG. 2A is a bottom view of various baffles operative in the present invention. [Figure 2B] FIG. 2B is a bottom view of various baffles operative in the present invention. [Figure 2C] FIG. 2C is a bottom view of various baffles operative in the present invention. [Figure 2D] FIG. 2D is a bottom view of various baffles operative in the present invention. [Figure 2E] FIG. 2E is a bottom view of various baffles operative in accordance with the present invention. [Figure 2F] FIG. 2F is a bottom view of various baffles operative in the present invention. [Figure 2G] FIG. 2G is a bottom view of various baffles operative in the present invention. [Figure 2H] FIG. 2H is a bottom view of various baffles operative in accordance with the present invention. [Figure 2I] FIG. 2I is a bottom view of various baffles operative in the present invention. [Figure 3A] FIG. 3A is a cross-sectional view of the ink cartridge of FIG. 1A with a single internal baffle embodiment. [Figure 3B] FIG. 3B is a bottom view of the configuration of FIG. 3A showing the orientation of the ribs of a single baffle. [Figure 3C] FIG. 3C is a diagram of the configuration of FIG. 1A with a side entry gas inlet. [Figure 4A] FIG. 4A is a side view of another embodiment of a printhead of the present invention including a replaceable ink cartridge of the present invention and an atomizer base. [Figure 4B] FIG. 4B is a cross-sectional view of the ink cartridge of FIG. 4A showing the nested baffle configuration. [Figure 5A] FIG. 5A is a first perspective view of a replacement ink cartridge according to the present invention. [Figure 5B] FIG. 5B is a perspective view of a portion of the aerosol chamber and baffle insert of FIG. 5A. [Figure 5C] FIG. 5C is a cross-sectional view of the insert of FIG. 5A along plane A-A'. [Figure 5D] FIG. 5D is a cross-sectional view of the insert of FIG. 5A along plane BB'. [Figure 6A] FIG. 6A is a bottom view of another embodiment of a portion of the aerosol chamber and baffle insert in an ink cartridge. [Figure 6B] FIG. 6B is a cross-sectional view of the insert of FIG. 6A along plane CC'. [Figure 6C] FIG. 6C is a second perspective view of the insert of FIG. 6A along the plane DD'. [Figure 7A]FIG. 7A is a first perspective view of another embodiment of an aerosol chamber and baffle insert. [Figure 7B] FIG. 7B is a partial cross-sectional view around the circle at the bottom left of the insert in FIG. 7A. [Figure 7C] FIG. 7C is a second perspective view of a portion of the aerosol chamber and baffle insert of FIG. 7A. [Figure 7D] FIG. 7D is a bottom perspective view of the top of the aerosol chamber and baffle insert of FIG. 7A in an ink cartridge of the present invention. [Figure 7E] FIG. 7E is a cross-sectional view of the insert of FIG. 7D along plane EE'. [Figure 7F] FIG. 7F is a cross-sectional view of the insert of FIG. 7D along plane FF'. [Figure 8A] FIG. 8A is a perspective view of another embodiment of an aerosol chamber and a portion of a baffle insert. [Figure 8B] FIG. 8B is an enlarged bottom view of the insert of FIG. 8A. [Figure 8C] FIG. 8C is a bottom perspective view of the insert of FIG. 8A in the context of an ink cartridge. [Figure 8D] FIG. 8D is a bottom view of the cartridge of FIG. 8C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention has utility as an aerosol-based printing device capable of providing an aerosol stream at a constant rate and depositing a constant material on a substrate to provide high definition, high resolution traces. The device of the present invention generates, transports, and delivers an aerosol stream at a constant rate for a constant period of operation of at least 8 hours, and in other cases exceeding 24 hours. The present invention is able to achieve and maintain excellent line width tolerances over long periods of time by inhibiting bulging and necking of the deposited traces, thereby enabling both the deposition of intricate traces and the consistent production of replica products that maintain tolerances over production runs. The present invention further eliminates the accumulation of fluids in the aerosol and gas transport conduits, eliminating the need for purging or cleaning cycles and allowing for uninterrupted operation for a minimum of 24 hours.

[0017] The present invention provides an apparatus capable of printing fine lines with sub-micron edge definition, enabling printing of 10 micron traces with 10 micron spacing. The apparatus produces a constant aerosol output at the substrate for at least 24 hours, and overcomes the fluid build-up problems of the prior art by isolating the transport gas input port and flow passages, and the aerosol output port and flow passages, from the agitated fluids produced by the atomization process of the present invention.

[0018] The present invention will be described with reference to the following embodiments. As will be apparent from these descriptions, the present invention can be embodied in different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. For example, features shown with respect to one embodiment may be incorporated in other embodiments, and features shown with respect to a particular embodiment may be deleted from the embodiment. In addition, numerous modifications and additions to the embodiments suggested herein will be apparent to those skilled in the art in light of this disclosure without departing from the invention. Thus, the following detailed description is intended to show some specific embodiments of the present invention, but is not intended to exhaustively specify all variations, combinations, and modifications thereof.

[0019] Where a range of values ​​is provided, it is to be understood that the range is intended to encompass not only the endpoints of the range, but also intermediate values ​​that are expressly included within the range and vary by the last significant digit of the range. By way of example, the stated range of 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the present specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention.

[0021] Unless otherwise indicated, explicitly or by context, the following terms are used herein as set forth below.

[0022] As used in the description of this invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0023] Additionally, as used herein, "and / or" refers to and includes any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative ("or").

[0024] An embodiment of the present invention provides a method and apparatus for aerosol-based direct printing of discrete patterns using a multi-lens aerodynamic focusing assembly and a material shutter assembly internal to the print head of the apparatus. The apparatus of the present invention generates discrete patterns by stopping a continuous stream of aerosol particles using a pneumatic shutter. According to an embodiment, the apparatus includes a printing module, a process vision module, a part alignment module, a shutter assembly, a process control module, and a motion control module. The printing module includes an aerosolization source, a pressure source, and a print head. The process vision module provides a real-time display of the deposition process. The alignment module is used to define vector distances between the axes of the alignment camera and one or more print heads and for substrate alignment. The process control module provides computer control and monitoring of gas flow rates and process temperatures, as well as monitoring of system pressure. The motion control module provides computer-controlled multi-axis motion of the substrate and coordinated shuttering of the aerosol stream. Rao, NP, “Aerodynamic focusing of particles in viscous jets,” Journal of Aerosol Science, 24, Issue 7, October 1993, Pages 879-892.

[0025] The present invention is capable of printing features from about 5 to 500 microns, and in some embodiments, can print features as small as 10 microns wide, spaced as few as 10 microns apart, and with shutter speeds as fast as about 10 milliseconds.

[0026] According to an embodiment, the present invention isolates the aerosol transport gas inlet port and gas delivery path from the ink fluid. The atomization process results in agitation of the ink that can contaminate the ink in the flow path of the gas used to transport the aerosolized ink droplets. Isolation of the gas flow path from the ink fluid is important and is achieved according to the present invention using an internal ink cartridge baffle.

[0027] Another important aspect of high definition, high density aerosol printing is the stable transport of aerosolized ink from the ink cartridge to the flow cell of the system. Fluid contamination in the ports and channels of the ink cartridge can result in alternating blocking and clearing of the aerosol flow path and aerosol output port, causing variations in the aerosol deposition rate. In accordance with the present invention, the elimination of fluid contamination in the aerosol flow path results in stable printing, allowing printing to operate for a minimum of 24 hours without interruption for servicing, provided that the ink and input gas supplies are maintained. In some present invention embodiments, stable printing occurs for more than 40 hours.

[0028] Referring now to the drawings, FIG. 1A shows an embodiment of the present invention of a printing module, generally designated 10, including an ink cartridge (1), an atomizer base (2), a cold plate (3), a flow cell (4), and a fluid dispensing tip (5). An ultrasonic transducer (6) atomizes the ink sample to form an aerosol, which is transported from the atomizer base (2) to the flow cell (4). A sheath gas enters the atomizer base (2) through a port (8) and forms an annular coaxial flow with the aerosol-laden gas, and the combined flow passes through the flow cell. Liu, P. “Generating Particle Beams of Controlled Dimensions and Divergence: II. Experimental Evaluation of Particle Motion in Aerodynamic Lenses and Nozzle Expansions”, Aerosol Science and Technology, Volume 22, 1995.

[0029] FIG. 1B shows a cross-sectional view of the ink cartridge (1) of FIG. 1A. The ink cartridge (1) has an inner surface (13). An ink sample is held in a removable vial (11). An aerosol transport gas enters the cartridge via a gas inlet tube (12). The aerosolized ink is transported from the aerosol chamber (17) to the flow cell (4) via an inclined channel (15) and a vertical channel (16), as detailed in U.S. Pat. No. 10,086,622 B2.

[0030] According to an embodiment of the invention, the aerosol gas input provided to the inclined channel (15) via the aerosol gas tube (12) and the aerosol output port is isolated from the ink outlet formed during the aerosolization process. The ink film formed at either the input or output port causes an intermittent supply of aerosol resulting in pulsed deposition on the substrate. In the embodiment of FIG. 1B, as shown in FIG. 1, the aerosol gas tube (12) is positioned such that the gas input through it is shielded from the ink outlet and the sample ink held in the removable vial (11) is isolated from the inclined channel (15) by the internal baffle (14). A constant flow of aerosol-laden gas exits the cartridge at a port (16) adapted for aerosol printing. The ink cartridge and the baffle are typically formed from aluminum, but may also be readily formed from more chemically resistant materials such as stainless steel or polyetheretherketone (PEEK). The internal baffle (14) is generally a cylindrical shell that serves to isolate the aerosol output channel (15) from the ink outlet. It will be appreciated that the internal baffle operative in accordance with the present invention produces a modified gas flow G.

[0031] The internal baffle is within the aerosol chamber and, in accordance with the present invention, has a variety of shapes as defined by a bottom view or a cross-sectional view. The shape of the baffle is selected such that the aerosol output channel is somewhat isolated from the ink outlet, and the isolation reduces aerosol settling and fluid accumulation to such an extent that fluid accumulation within the ink cartridge and transport conduit does not require purging for at least 8 hours. As a result, printing can occur uninterrupted for at least 8 hours.

[0032] Internal baffle shapes operable herein illustratively include planar (FIG. 2A), arcuate (FIG. 2B), segmented cylindrical (FIGS. 2C-2E), acute angled (FIG. 2F), and complex shapes such as S-shaped (FIG. 2G), and Y-shaped (FIGS. 2H-2I). With reference to FIGS. 2A-2I, these shapes typically define an angle α that varies from 5 to 180 degrees as shown. Factors relevant to selecting a given shape of the internal baffle include aerosol droplet size, ink surface tension, temperature, inlet gas flow rate, and gap dimension along the gas flow G.

[0033] As used herein, "continuous printing" is defined as printing and depositing ink droplets on a substrate for at least 8 hours without resorting to a purge cycle, whether the purge cycle is automatic or manually performed, in contrast to conventional aerosol-based ink cartridges that are only capable of approximately 30 minutes of continuous printing.

[0034] Another embodiment of the present invention is shown in FIG. 3A, where like reference numerals have the previously mentioned meanings with respect thereto. An ink cartridge (1) is provided that includes a single baffle (22) and an aerosol gas input that enters the cartridge along the outside of the baffle (22) via input port (19). As shown in FIG. 3B, a set of ribs (23) directs the aerosol gas down along the baffle (22) to the bottom of the aerosol chamber (17). The configuration of FIGS. 3A-3C prevents fluid contamination at the gas input port (19) and the aerosol output port (16). A constant flow of aerosol-laden gas exits the cartridge at port (16). In the present invention, stable aerosol transport is achieved by isolating the fluid outlets generated by the atomization process from the input and output ports of the ink cartridge. When ultrasonic energy is coupled into the ink, the surface of the ink begins to vibrate, forming an outlet near the center of the fluid. As shown in Figures 3A-3C, isolation of the outlet from the input and output ports is achieved using a single baffle and a series of vertical ribs that force the aerosol gas to flow downward to the bottom of the ink cartridge. According to an embodiment, the aerosolized droplets are entrained in a transport gas and transported from the ink cartridge to a flow cell. Figure 3C shows a cartridge configuration similar to that of Figure 3A, where the aerosol gas enters the aerosol chamber through port (19) on the side of the cartridge and near the bottom of the aerosol chamber. The aerosol exits the cartridge at port (16). The configuration of Figure 3C may be used with an internal baffle without ribs.

[0035] According to an embodiment as shown in FIG. 4A, the device of the present invention includes an atomizer base (38), an ink cartridge (34) and an ink cartridge cap (36). The flow paths of the input aerosol gas and the aerosol-laden output gas are generally shown in cross-section in FIG. 4B. As shown in FIG. 4B, the device includes a set of nested baffles (30) and (32) to isolate the gas input and output from the ink outlet. The aerosol transport gas enters the cartridge at an input port (19) located off-axis relative to the aerosol chamber axis and the ink outlet. The aerosol gas flows downward into the aerosol chamber (17) and to the bottom of the baffles (30) and (32). The inner baffle (30) prevents fluid from entering the angled output channel (15) and isolates the gas input from the ink outlet, while the outer baffle (32) directs the aerosol gas downward into the region of highest aerosol density. A constant flow of aerosol-laden gas exits the cartridge at port (16). Two concentric cylindrical internal baffles (30) and (32) are used to isolate the ink outlet from the gas input and aerosol output ports of the ink cartridge. The nested baffle configuration eliminates fluid entrainment in the gas and aerosol flow paths.

[0036] As shown in the following figures, the removable vial (11) is not shown to better illustrate the internal baffle and its effect on the aerosol gas flow path, as indicated by the arrows in the figure. FIG. 5A is a first perspective view of an alternative ink cartridge (40) showing the aerosol gas inlet (42), aerosol chamber (44), and baffle insert (46). FIG. 5B is a perspective view of a portion of the aerosol chamber (44) and baffle insert (46) of FIG. 5A showing the complex shaped aerosol gas diverter (48) and reverse gas flow. FIG. 5C is a cross-sectional view of the insert of FIG. 5A along plane A-A', showing the aerosol gas input (42) and aerosol gas diverter (48). FIG. 5D is a cross-sectional view of the insert of FIG. 5 along plane B-B', showing the flow path of the aerosol gas flow path as it travels up the angled output channel (15) and isolates the gas input (42) from the ink outlet (16).

[0037] Figure 6A is a bottom view of another embodiment of an aerosol chamber (44) and a portion of a baffle insert (48) in an ink cartridge (50). Figure 6B is a cross-sectional view of the insert of Figure 6A along plane C-C'. Figure 6C is a second perspective view of the insert of Figure 6A along plane D-D'.

[0038] FIG. 7A is a first perspective view of another embodiment of an aerosol chamber and baffle insert (60) functioning as an aerosol gas diverter with a baffle (62) with an acute angle. FIG. 7B is a partial cutaway view around the dotted circle at the bottom left of the insert (60) of FIG. 7A. FIG. 7C is a second perspective view of a portion of the aerosol chamber and baffle insert (60) of FIG. 7A. FIG. 7D is a bottom perspective view of the top of the aerosol chamber and baffle insert (60) of FIG. 7A in an ink cartridge (70) of the present invention. FIG. 7E is a cross-sectional view of the baffle insert (60) of FIG. 7D along plane E-E'. FIG. 7F is a cross-sectional view of the baffle insert (60) of FIG. 7D along plane F-F'.

[0039] Figure 8A is a perspective view of another embodiment of an aerosol chamber and a portion of a baffle insert (80). Figure 8B is an enlarged bottom view of the baffle insert (80) of Figure 8A showing that the aerosol chamber is divided into an aerosol gas input region (82), an aerosol generation chamber (84), and an output region (86) filled with aerosol ink. Figure 8C is a bottom perspective view of the baffle insert of Figure 8A in the context of an ink cartridge (90). Figure 8D is a bottom view of the ink cartridge (90) of Figure 8C.

[0040] It should be appreciated that the footprints of the embodiments of the ink cartridges (1, 40, 50, 70, 90) are comparable, allowing for interchangeable use in a printing press.

[0041] Embodiments of the present invention provide methods and apparatus for printing high density, high definition features directly onto a substrate at ambient conditions. Of particular interest is the provision of processes and apparatus that provide stable and repeatable deposition of liquids onto substrates for additional manufacturing applications, including, but not limited to, metallization of rigid and flexible substrates, deposition of inorganic and organic samples for sensor applications, and deposition of various inks for green energy applications such as solar cell metallization and fuel cell manufacturing. According to embodiments, the apparatus of the present invention is capable of printing 10 micron wide lines spaced 10 microns apart, enabling high density applications such as interconnect redistribution.

[0042] According to embodiments, a constant aerosol output is delivered to the surface, enabling printing of high definition, high density patterns. The aerosol output rate to the surface is held constant by minimizing pulsation of the aerosol flow at the aerosol output port of the ink cartridge, maintaining a constant gas flow rate to and from the cartridge, and maintaining a constant aerosol density in the area where the aerosol is extracted from the cartridge. According to embodiments, the present invention minimizes the horizontal distance that the aerosol must travel to exit the ink cartridge. For aerosol droplet size distributions generated by a typical atomizer, aerosol settling occurs after approximately 5-10 millimeters of horizontal travel. Aerosol settling can lead to liquid accumulation in the ink cartridge, causing fluctuations in the aerosol output rate. Thus, according to embodiments, the present invention limits the horizontal travel of the aerosol-laden gas to approximately 10 millimeters or less.

[0043] Ink contamination in the gas input or aerosol output of the ink cartridge can lead to pulsing or fluctuations in the aerosol output to the surface. Ink contaminated in the output or input ports can form a film that partially or completely blocks the port. Ink contamination in the input and output ports of the ink cartridge causes fluctuations in the aerosol output rate as the ports are alternately blocked and cleared. The internal pressure of the cartridge increases and decreases accordingly. Thus, fluctuations in the mass flux of the aerosol delivered to the surface can result in variations in the printed trace line width and lead to bulging or necking of the traces that can adversely affect the electrical and mechanical properties of the deposited traces. The occlusion condition causes a momentary decrease in the aerosol output, followed by an increase in the aerosol output rate as the pressure increases, and the occlusion condition is cleared when the pressure increases above a critical value. According to the present invention, pulsing or fluctuations in the aerosol output are avoided by using a combination of a baffle, or a baffle and a set of vertical ribs that isolate the gas input and aerosol output ports from the ink outlets generated by the ultrasonic aerosolization process.

[0044] Another feature provided in accordance with an embodiment of the present invention is a constant aerosol gas flow rate to produce a constant aerosol output. The present invention uses a mass flow controller to maintain the aerosol gas flow rate at or below about 2 percent of the set aerosol gas flow rate value. Similarly, the output rate of the aerosol gas is held constant by achieving a saturated or near-saturated aerosol density within the capacity of the ink cartridge. Once the saturated aerosol density condition is reached, minor variations in aerosol production result in little or no change in the aerosol density in the ink chamber, allowing for a constant aerosol output.

[0045] High power, low gas flow atomizers are highly stable and allow for the production of dense and narrowly dispersed aerosol distributions tuned to the optimal or near optimal size range of the focusing assembly. According to embodiments, tunable or fixed frequency atomizers, interchangeable and tunable single or multi-stage aerodynamic lens systems, and annularly flowing sheath gas are used. The combination of the use of coaxial sheath flow and aerodynamic lenses forms a hybrid hydrodynamic / aerodynamic focusing device that collimates and deposits a stream of particles with diameters in the range of about 0.5-5 microns.

[0046] In hydrodynamic focusing, an inner fluid or gas stream loaded with an aerosol is surrounded by a co-propagating annular sheath fluid or gas. When the combined streams flow through an orifice or series of orifices, the volume available for the inner flow is reduced by the volume occupied by the outer sheath flow. Hydrodynamic focusing occurs when a reduction in the inner flow rate causes a reduction in the diameter of the inner stream, which is proportional to the ratio of the flow rates of the aerosol and the sheath gas.

[0047] An aerodynamic lens is a flow configuration in which particle-laden gas passing through a cylindrical channel passes an orifice where the gas undergoes one contraction upstream of the orifice and then a short while later an expansion downstream of the orifice. The contraction of the aerosol stream occurs as the flow approaches and passes the orifice. The gas then expands as the flow propagates downstream into a wider cross-sectional area. The flow directs particles through the orifice towards the flow axis, so that the aerosol stream becomes narrow and collimated.

[0048] The ability to focus droplets entrained in a gas stream is related to the Stokes number St of the droplets. It is generally accepted that optimal focusing of the aerosol is obtained when St equals 1. Unfocused droplets can generally be classified as overspray or satellite deposition. Overspray deposition occurs when small droplets pass through the lens assembly at low Stokes numbers without achieving a Stokes number close to 1 at any stage of the assembly. Conversely, satellite droplets are produced when large droplets with Stokes numbers much greater than 1 pass through each stage of the assembly.

[0049] Yet another unique aspect of the present invention is the ability to print high density circuits in two or three dimensions, in particular high definition, high density 3D circuits with conductive layers separated by insulating layers and with interconnect vias that carry power and signals between the conductive layers.

[0050] The print module's replaceable ink cartridges can be used to print multi-layer, multi-material circuits in which vertical interconnects are formed between insulated conductive layers. According to an embodiment, the apparatus of the present invention facilitates printing multi-layer vertical circuits because a single tool, the flow cell, is used to print each layer. The conductive layers are connected by printing vias directly into the insulating layers and printing interconnects in the vias to connect two successive conductive layers.

[0051] Another unique aspect of the present invention is the elimination of the requirement for tool offset definition between printing of single or multi-layer multi-material circuits. In a multi-layer printing process, the tool (flow cell) remains fixed and the print is changed using replaceable ink cartridges. In such a method, high precision printing can be performed since each layer is assigned the same reference point and there is no need to determine the vector distance between two or more printing tools.

[0052] According to an embodiment, the substrate is attached to the platen, either mechanically or using vacuum. The platen is connected to a multi-axis motion control system so that when combined with an aerosol shutter process, the atomizer, flow cell, motion control, and platen assembly allows for printing and material processing of discreet patterns and structures on the substrate. The platen can be heated to approximately 150° C., allowing for real-time curing or sintering of the deposited material.

[0053] According to an embodiment, the device includes a multi-nozzle array, in which an assembly including multiple outlet nozzles with sheath flow is fabricated, for example in a linear array, thus allowing simultaneous deposition from each nozzle.

[0054] According to an embodiment, the present invention may further be used to build three-dimensional structures using a layer-by-layer process, where simple and complex objects are printed directly from computer-aided design (CAD) files. In the 3D printing process, laser-assisted deposition or viscoelastic inks are used to deposit liquid filaments of sufficient viscosity to form rigid or semi-rigid structures, on which subsequent layers are deposited. In the 3D printing technique, a digital model of an object is intersected by horizontal planes. The horizontal planes form a cross-sectional representation or slice of the object. The information of each slice is uploaded to a computerized motion control system so that a solid object can be manufactured using an additive manufacturing process. This process may be used to manufacture three-dimensional objects from materials including, but not limited to, metals, ceramics, and plastics.

[0055] The apparatus of the present invention further enables the printing of multi-layer high definition circuits or patterns. A high definition, high density printed circuit or pattern is defined as an assembly of traces having line widths of about 30 microns or less and spacings of about 50 microns or less. The present invention uses replaceable ink cartridges or multi-material printheads to print high definition, high density circuits or patterns.

[0056] The patent documents and publications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains, and are hereby incorporated by reference to the same extent as if each individual document or publication was specifically and individually incorporated by reference herein.

[0057] The foregoing description illustrates certain embodiments of the present invention, but is not meant to limit its practice. The following claims, including all equivalents thereof, are intended to define the scope of the present invention.

Claims

1. 1. An aerosol printing ink jet cartridge comprising: a housing having an interior wall defining an aerosol chamber; a removable vial adapted to store an aerosol ink and configured to be in fluid communication with the aerosol chamber of the housing; at least one internal baffle extending from the inner wall of the housing and disposed within the aerosol chamber of the housing, the internal baffle configured to extend at least partially into the removable vial to separate an aerosol chamber; a gas inlet tube adapted to supply an inlet gas to the aerosol chamber; an outlet channel in fluid communication with the aerosol chamber through which the aerosol ink is output as particles, the outlet channel being isolated from the aerosol ink in the removable vial by the at least one internal baffle.

2. 10. The aerosol printing ink jet cartridge of claim 1, wherein the at least one baffle is a single baffle.

3. 10. The aerosol printing ink jet cartridge of claim 1, wherein a bottom surface of at least one baffle has a shape that is planar, arcuate, segmented cylindrical, acute angled, S-shaped, or Y-shaped.

4. 4. The aerosol printing ink jet cartridge of claim 3, wherein the shape of the bottom surface is such that the opening angle α of the bottom surface is between 5 and 180 degrees.

5. 3. The aerosol printing ink jet cartridge of claim 2, wherein the bottom surface of said single baffle is planar.

6. 3. The aerosol printing ink jet cartridge of claim 2, wherein the bottom surface of said single baffle is arcuate.

7. 3. The aerosol printing ink jet cartridge of claim 2, wherein the bottom surface of the single baffle is a split cylinder.

8. 3. The aerosol printing ink jet cartridge of claim 2, wherein the bottom surface of said single baffle is sharply shaped.

9. 3. The aerosol printing ink jet cartridge of claim 2, wherein the bottom surface of the single baffle is S-shaped.

10. 3. The aerosol printing ink jet cartridge of claim 2, wherein the bottom surface of the single baffle is Y-shaped.

11. The aerosol printing inkjet cartridge of claim 1, further comprising a set of ribs projecting outwardly from the at least one baffle.

12. 12. An aerosol printing ink jet cartridge according to any preceding claim, wherein the gas inlet conduit supplies the inlet gas within the aerosol chamber and inside the at least one internal baffle.

13. 12. The aerosol printing ink jet cartridge of claim 1, wherein the gas inlet conduit supplies the inlet gas within the aerosol chamber and outside the at least one internal baffle.

14. 12. The aerosol printing ink jet cartridge of claim 1, wherein the outlet channel comprises an angled channel joining a port.

15. 1. An apparatus for printing discrete, high resolution, high density features on a surface using an aerosol stream, comprising: A cartridge according to claim 1; an atomizer positioned to atomize the aerosol ink; a flow cell including at least one aerodynamic lens and a convergent fluid dispensing nozzle having a sheath gas flow around the periphery; a non-contact, pneumatic shutter assembly positioned to selectively interfere with the nozzle stream.

16. 16. The device of claim 15, wherein the atomizer has variable excitation, continuous excitation, or pulsed excitation.

17. The device of claim 15 , wherein the atomizer includes an ultrasonic transducer configured to atomize the ink.

18. The device according to any one of claims 15 to 17, wherein the vial is removable.

19. Apparatus according to any one of claims 15 to 18, wherein at least one aerodynamic lens has an operational range that matches the mean diameter of the atomizer aerosol distribution for the purpose of collimating mid-sized particles.

20. 19. The apparatus of any one of claims 15 to 18, wherein the sheath flow rate of fluid through the aerodynamic lens assembly and the exit nozzle is set to accommodate large and small particles in the aerosol distribution for the purpose of focusing particles to any size.

21. An apparatus according to any one of claims 15 to 18, wherein a non-contact, pneumatic shutter assembly is internal and configured to achieve shutter times as fast as 10 milliseconds.

22. The apparatus according to any one of claims 15 to 18, further comprising a multi-nozzle array comprising several outlet nozzles.

23. A method of printing traces on a substrate using an apparatus according to claim 15, comprising the steps of: Providing an aerosol ink in a vial; introducing an aerosol transport gas into the cartridge via a gas inlet tube; atomizing the aerosol ink using an ultrasonic transducer of the atomizer to create an aerosol-laden gas; introducing a sheath gas through a port into the atomizer to form an annular coaxial flow with the aerosol-laden gas to create a combined flow; passing the combined flow through a flow cell; and outputting the aerosol-laden gas from an output port at a constant flow rate.

24. The method of claim 23 further comprising the step of printing continuously for 8 to 24 hours.

25. 24. The method of claim 23, further comprising replacing the inkjet cartridge with a second inkjet cartridge.

26. The method of claim 23 , wherein the substrate is an additive manufacturing application substrate.

27. The method of claim 23 , wherein the substrate is a sensor application substrate.

28. 24. The method of claim 23, wherein the substrate is a solar cell metallization or a fuel cell substrate.

29. The method of any one of claims 23 to 28, wherein the output is under ambient conditions of standard temperature and pressure.

30. 24. The method of claim 23 used to print high density circuits in two or three dimensions.

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