Fabrication of 3-dimensional multi-layer electronics by direct ink writing
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-06
- Publication Date
- 2026-08-13
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Figure US2026014213_13082026_PF_FP_ABST
Abstract
Description
Patent Application 3611-00-028W01FABRICATION OF 3-DIMENSIONAL MULTI-LAYER ELECTRONICS BY DIRECT INK WRITINGCross-reference to Related Application
[0001] This application claims the benefit of U. S. Application No. 63 / 755,989, filed on February 7, 2025, the disclosure of which is incorporated herein by reference in its entirety.Field of the Invention
[0002] The present disclosure relates generally to novel methods for preparing 3-dimensional multi-layer structured electronics on non-conductive substrates. The disclosure also relates to 3-dimensional multi-layer electronic structures prepared according to the disclosed methods.Background of the Invention
[0003] The fabrication of 3 -dimensional, multi-layered conductive structures for use in modern electronic devices is of growing importance. Traditional manufacturing processes are limited, however, by limited resolution, waste, long processing times, difficulty in application to flexible substrates, and high cost, among other reasons.
[0004] There is thus a need for improved methods for fabrication of 3-dimensional multi-layer structured electronics that result in high- resolution structures, that offer flexible design, short process times, and zero-waste production, and that are cost effective. There is also a need for 3 -dimensional multi-layer electronic structures prepared using such methods.Summary of the Invention
[0005] In some aspects, the techniques described herein relate to a method for fabricating a multi-layer electronic stmcture including the steps of: providing a substrate;depositing a first conductive ink on the substrate; curing the first conductive ink on the substrate to form a first conductive layer; depositing a first dielectric ink on the first conductive layer; and curing the first dielectric ink on the first conductive layer to form a first dielectric layer.
[0006] In some aspects, the techniques described herein relate to a multi-layer structure including: a substrate; a first conductive layer on the substrate; and a first dielectric layer on the first conductive layer, wherein the multi-layer structure is prepared by depositing a first conductive ink on the substrate; curing the first conductive ink on the substrate to form the first conductive layer; depositing a first dielectric ink on the first conductive layer; and curing the first dielectric ink on the first conductive layer to form the first dielectric layer.Brief Description of the Drawings
[0007] FIG. 1 illustrates steps used in printing process for generating 3-dimensional multi-layer structure.
[0008] FIGs. 2A-2E graphically illustrates various printing processes with a metal-organic decomposition (MOD) ink.
[0009] FIG. 3 graphically illustrates the inkjet printed layer on flexible substrate in accordance with aspects of the invention.
[0010] FIG. 4 illustrates the micro structured aerosol printed gold sensor on flexible substrate in accordance with aspects of the invention.
[0011] FIG. 5 graphically illustrates the characteristics of a target surface (substrate) after in-situ UV curing.
[0012] FIGs. 6A, and 6B show a 3-dimensional printed capacitor structure and the respective structural layers in accordance with aspects of the invention.
[0013] FIGs. 7A-7C illustrate the micro structured printed circuit board (PCB) and the respective structural layers in accordance with aspects of the invention.Detailed Description of the Invention
[0014] The current disclosure addresses the need for improved methods for the fabrication of 3-dimensional multi-layered structured electronics and for structures prepared according to these methods. In particular, the disclosure provides direct ink write (DIW) printing methods for preparing such structures.
[0015] The disclosure also provides electronic structures prepared using the disclosed methods, including electronic structures that comprise alternating layers of conductive structures and dielectric structures. These electronic structures are prepared by printing alternating layers of conductive inks and dielectric inks in desired patterns with suitable alignment of the alternating layers.
[0016] Traditional fabrication methods for 3-dimensional multi-layer electronic structures rely on either wet chemical etching processes for the production of large-scale devices or photolithographic processes for the production of micro-scale devices. Wet chemical etching methods produce large amounts of toxic waste and are not capable of producing structures with resolutions significantly less than 100 pm. Photolithographic methods require long processing times due to the complexity of manufacturing and are expensive. Neither wet chemical etching nor photolithographic processes are capable of patterning structures on flexible substrates.
[0017] In contrast to traditional approaches, the use of direct ink write (DIW) printing methods enables the selective deposition of different materials, in particular, different conductive and dielectric materials, that allow multi-layer structures to be fabricated slide by slide. These approaches allow for easy design, for example, approaches using computer-aided design (CAD) files that can be changed and modified easily. The approaches result in little to no waste in the manufacturing process, since conductive and dielectric inks are deposited only on desired design areas. The lack of waste is advantageous both from an environmental and cost basis. The approaches are highly accurate, with resolutions ranging from micron to meter scale, depending on the deposition method. The approaches are also able to be applied to both rigid and flexible substrates. Finally, the approaches can take advantage of a wide variety of printable materials, including conductive and dielectric inks that can be cured using, for example, low temperatures and / or UV treatments.
[0018] FIG. 1 illustrates an exemplary printing process flow for the preparation of an exemplary 3-dimensional multi-layer conductive structure. In step 1, a conductive ink is printed on a suitable non-conductive substrate to generate a first conductive structure with a desired conductive pattern. This step can include the printing of alignment marks for use in subsequent printing steps. The conductive ink can be any suitable conductive ink, as will be described in more detail below. In step 2, the conductive structure is formed bycuring the conductive ink using either a thermal or light (e.g., UV) treatment. In step 3, a first dielectric structure is generated on top of the first conductive structure. The first dielectric structure is formed by printing a dielectric ink on the surface of the first conductive structure and curing the dielectric ink, preferably using a UV curing process. The first dielectric structure can be aligned on the first conductive structure using alignment marks during the printing step. Printing of subsequent conductive structures, for example as shown in step 4, and subsequent dielectric structures using alternating layers of conductive inks and dielectric inks results in the desired 3-dimensional multilayer electronic structure.
[0019] The conductive inks used to form the conductive structures of the 3-dimensional multi-layer conductive structures of the instant disclosure are preferably generated using a conductive ink composition that can be applied with high uniformity to a target surface. Any suitable conductive ink composition can be used to generate the conductive structure. For example, the conductive ink composition can be a nanoparticulate ink, a microparticulate ink, a carbon ink, a copper sulfate ink, a conductive polymer ink, or a metal complex or MOD ink. The conductive ink composition is preferably a metal complex or MOD ink.
[0020] The conductive inks used to form the conductive structures of the methods and structures disclosed herein can comprise any suitable metal. Exemplary metallic inks can be, for example, silver, copper, palladium, gold, platinum, indium, or nickel inks. In preferred embodiments, however, the conductive ink is a silver ink, a gold ink, or a platinum ink. Most preferably, the conductive ink is a silver ink.
[0021] The conductive features of the 3-dimensional multi-layer structures that are generated according to the methods disclosed herein can have significantly higher resolution than those prepared according to known techniques. For example, in some embodiments these electroplated target surfaces can comprise a plurality of patterned conductive lines wherein at least one patterned conductive line has a width of no more than 10 pm, no more than 5 pm, no more than 2 pm, no more than 1 pm, no more than 0.5 pm, or even narrower. Preferably at least one patterned conductive line has a width of no more than 1 pm. In some embodiments, these structures can comprise a plurality of patterned spaces between the patterned conductive lines wherein at least one patterned space has a width of no more than 10 pm, no more than 5 pm, no more than 2 pm, nomore than 1 pm, no more than 0.5 pm, or even narrower. Preferably at least one patterned space has a width of no more than 1 pm.Methods for Fabricating a Multi-Layer Electronic Structure
[0022] According to one aspect, the current disclosure provides novel methods for fabricating a multi-layer electronic structure. In particular, these methods can result in a multi-layer electronic structure having alternating conductive and dielectric layers. These methods can include, for example, the steps of providing a substrate for forming the multilayer structure, depositing a first conductive ink on the substrate, curing the first conductive in on the substrate to form a first conductive layer, depositing a first dielectric ink on the first conductive layer, and curing the first dielectric ink on the first conductive layer to form a first dielectric layer.
[0023] The target substrate used in the methods can be any suitable substrate that is compatible with the treatment steps. The target substrate is typically an exposed surface of a suitable non-conducting substrate. Where the conductive ink is converted to a conductive layer by a heat treatment, the target substrate is preferably capable of being heated to a threshold temperature that is sufficient to convert the conductive ink to the conductive layer in a reasonable time. Since the temperature necessary to form a conductive layer from the conductive inks typically used in these methods is low, most materials suitable for use in the subsequent steps are also suitable for use as target substrates for the conductive layer. The target substrate should be suitably adherent, both for the conductive ink itself and for the conductive layer formed from the ink. The target substrate is preferably not sensitive to the components of the conductive ink compositions used in the process, for example any of the solvents or reactive agents present in the conductive ink. The target substrate is also preferably compatible with the conditions used in the subsequent treatment step or steps.
[0024] Exemplary target substrates can be organic surfaces or inorganic surfaces, for example, glass, metal, thermoplastic, or silicon substrate. More specifically, target substrates can comprise, without limitation, polyimide, epoxy with glass reinforcement, buildup films with no reinforcement, glass, silicon, passivated metals, bare metals, ceramics, engineered plastics, or three-dimensional (3D)-printable materials. An exemplary buildup film is Ajinomoto Build-up Film® (ABF). In some embodiments, thesubstrate can be any insulating material typically used to prepare a printed circuit board (PCB).
[0025] The target substrate can in some embodiments be associated with a heat source, so that the target substrate can be heated to, or above, a threshold temperature prior to application of the conductive ink to the substrate. In some embodiments, the target substrate is in direct physical contact with the heat source. In other embodiments, the target substrate is heated through space by a heat source that is not in direct physical contact with the target substrate. Examples of heat sources include an IR lamp, an oven, a platen, or a heated substrate.
[0026] As just described, in some embodiments, the instant methods include the step of heating the target substrate to a threshold temperature. More specifically, the target substrate is heated to a threshold temperature of about 21 °C or more, about 30 °C or more, about 40 °C or more, about 50 °C or more, about 60 °C or more, about 70 °C or more, or even about 80 °C or more. In some embodiments, the target substrate is heated to a threshold temperature of about 250 °C or less, of about 230 °C or less, of about 210 °C or less, of about 200 °C or less, of about 190 °C, of about 180 °C or less, of about 170 °C or less, of about 160 °C, of about 150 °C or less, of about 140 °C or less, of about 130 °C or less, of about 120 °C or less, of about 110 °C or less, or even of about 90 °C or less. The threshold temperature reflects the temperature required to convert the conductive ink to a conductive layer. In other words, at the threshold temperature, the conductive ink forms a conductive structure upon application to the heated target substrate. In some embodiments, the conductive ink is cured by heating the ink at the above temperatures after the ink has been deposited on the target substrate.
[0027] In some embodiments, the conductive ink is cured by photo activation, for example by irradiation of the conductive ink on the target substrate. More specifically, the irradiating step can be performed by exposing the conductive ink to a light source at a wavelength from about 100 nm to about 1500 nm. In some embodiments, the irradiating step can be performed by exposing the conductive ink to a light source such as a Xenon lamp, an IR lamp, or a laser at a wavelength from about 100 nm to about 1000 nm. In some embodiments, the irradiating step can be performed by exposing the conductive ink to a light source at a wavelength from about 100 nm to about 700 nm. In some embodiments, the irradiating step can be performed by exposing the conductive ink to alight source at a wavelength from about 100 nm to about 500 nm. In some embodiments, the irradiating step can be performed by exposing the conductive ink to a light source at a wavelength from about 100 nm to about 300 nm. In some embodiments, the irradiating step can be performed by exposing the conductive ink to a light source at a wavelength of about 100 nm, about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, or about 1000 nm.
[0028] In some embodiments, the conductive ink is applied by slot die coating, spin coating, roll-to-roll printing, including gravure, flexography, rotary screen printing, screen printing, aerosol jet printing, inkjet printing, airbrushing, Mayer rod coating, flood coating, 3D printing, dispenser, or electrohydrodynamic printing. More specifically, the ink can be applied by aerosol jet printing, inkjet printing, dip coating, or spray coating. In preferred embodiments, the ink is applied by aerosol jet printing or inkjet printing so that a patterned conductive layer of suitable design can be formed on the target substrate. In other preferred embodiments, the ink is applied by spray coating so that large areas of a target substrate can be covered uniformly and consistently by the conductive ink.
[0029] In some embodiments, the conductive ink is applied under ambient pressure. In other embodiments, the conductive ink is applied under a reduced pressure.
[0030] In some embodiments, the conductive ink is applied by a spray coating tool. In more specific embodiments, the spray coating tool comprises a moveable spray head. In other specific embodiments, the conductive ink is applied by a spray coating tool without moving the target surface.
[0031] In some embodiments, the conductive layer is formed on the target surface using the methods for metallization or seed layer formation disclosed in U. S. Patent Application Nos. 63 / 638,602, filed on April 25, 2024, or 63 / 686,652, filed on August 23, 2024, the disclosures of which are incorporated herein by reference for all purposes.
[0032] In some embodiments, the four-point resistance of the conductive layer formed on the target substrate is measured. In some embodiments, the four-point resistance of the conductive layer is about 10 Ohm or less. In some embodiments, the four-point resistance of the conductive layer is about 1 Ohm or less. In some embodiments, the four-point resistance of the conductive layer is about 500 mOhm or less, is about 300 mOhm or less, is about 100 mOhm or less, is about 30 mOhm or less, or is even lower.
[0033] In some embodiments, the resistivity of the conductive layer formed on the target substrate is measured. Suitable resistivities can be, for example, from about 2 to about 5 p Ohm-cm, from about 4 to about 9 p Ohm-cm, or even from about 28 to about 42 pOhm-cm.
[0034] In some embodiments, the electrical conductivity of the conductive layer formed on the target substrate is measured. In some embodiments, the electrical conductivity of the conductive layer is about lx 10’6Ohm-cm or greater. In some embodiments, the electrical conductivity of the conductive layer is from about IxlO-6Ohm-cm to about 8xl0-4Ohm-cm. In some embodiments, the electrical conductivity of the conductive layer is from about 3x1 O’6Ohm-cm to about 6x1 O’6Ohm-cm. In some embodiments, the electrical conductivity of the conductive layer is at least about IxlO-6Ohm-cm, about 2x1 O’6Ohm-cm, about 3xl0'6Ohm-cm, about 4xl0-6Ohm-cm, about 5xl0-6Ohm-cm, about 6xl0'6Ohm-cm, about 7x106Ohm-cm, about 8x106Ohm-cm, about 9x106Ohm-cm, about IxlO25Ohm-cm, about 2xl0:’ Ohm-cm, about SxlO2’ Ohm-cm, about 4xl0-:iOhm-cm, about 5xl0-5Ohm-cm, about 6xl0-5Ohm-cm, about 7xl0-5Ohm-cm, about 8x 10"’ Ohm-cm, about 9x10'5Ohm-cm, about IxlO-4Ohm-cm, about 2x10’4Ohm-cm, about 3x10’4Ohm-cm, about 4x Iff4Ohm-cm, about 5xl0-4Ohm-cm, about 6xl0-4Ohm-cm, or about 7xl0-4Ohm-cm. In some embodiments, the electrical conductivity of the conductive layer is at most about 8xl0-4Ohm-cm, 7x1 O’4Ohm-cm, about 6x1 O’4Ohm-cm, about 5x1 O’4Ohm-cm, about 4x Iff4Ohm-cm, about 3xl0-4Ohm-cm, about 2xl0-4Ohm-cm, or about IxlO'4Ohm-cm, about 9xl0-5Ohm-cm, about 8xl0-5Ohm-cm, about 7xl0-5Ohm-cm, about 6X10'3Ohm-cm, about 5x 1(0 Ohm-cm, about 4x ICO Ohm-cm, about 3xl0‘5Ohm-cm, about 2x1(0 Ohm-cm, about IxlO-5Ohm-cm, about 9xl0-6Ohm-cm, about 8xl0‘6Ohm-cm, about 7xl0'6Ohm-cm, about 6xl0-6Ohm-cm, about 5xl0’6Ohm-cm, about 4x10"6Ohm-cm, about 3xl0-6Ohm-cm, or about 2xl0'6Ohm-cm.
[0035] The electrical conductivity of the conductive layer formed on the target substrate using the above methods may in some embodiments be expressed in terms of sheet resistance (i.e., bulk resistivity divided by thickness) in units of Ohms per square (also referred to as Ohms / square or OPS). For example, in some embodiments, the resistance of the conductive layer is no more than 10 Ohms per square, no more than 5 Ohms per square, no more than 3 Ohms per square, no more than 2 Ohms per square, no more than 1Ohm per square, no more than 0.5 Ohms per square, or even lower. Preferably, the resistance of the conductive layer is no more than 5 Ohms per square.
[0036] The methods of the instant disclosure can be used to form conductive layers having high levels of bulk metal. Specifically, in some embodiments, the conductive layer formed on the target substrate has a bulk metal content of at least 1%. In more specific embodiments, the conductive layer has a bulk metal content of at least 2%, at least 5%, at least 10%, at least 15%, at least 20%, or even higher.
[0037] The conductive layer formed on the target substrate can in some embodiments be at least about 0.003 pm thick, at least about 0.005 pm thick, at least about 0.01 pm thick, at least about 0.02 pm thick, at least about 0.05 pm thick, at least about 0.1 pm thick, at least about 0.2 pm thick, at least about 0.5 pm thick, at least about 1 pm thick, at least about 2 pm thick, at least about 3 pm thick, at least about 4 pm thick, at least about 5 pm thick, at least about 8 pm thick, at least about 10 pm thick, at least about 20 pm thick, or even thicker. In some embodiments, the conductive layer formed on the target substrate can be no more than about 200 pm thick, no more than about 100 pm thick, no more than about 50 pm thick, no more than about 20 pm thick, no more than about 10 pm thick, no more than about 8 pm thick, no more than about 5 pm thick, no more than about 2 pm thick, no more than about 1 pm thick, no more than about 0.5 pm thick, no more than about 0.2 pm thick, not more than about 0.1 pm thick, no more than about 0.05 pm thick, no more than about 0.02 pm thick, no more than about 0.01 pm thick, or even thinner. In some embodiments, the conductive layer formed on the target substrate can be from about 0.003 pm thick to about 0.1 pm thick, from about 0.003 pm thick to about 0.5 pm thick, from about 0.003 pm thick to about 1 pm thick, from about 0.003 pm thick to about 5 pm thick, from about 0.5 pm thick to about 10 pm thick, or from about 1 pm thick to about 5 pm thick. The thickness of the conductive layer formed on the target substrate can in some embodiments have a deviation in thickness of no more than about 30%, no more than about 20%, no more than about 10%, or even no more than about 5%.Conductive Ink Compositions
[0038] Conductive ink compositions suitable for use in forming conductive layers according to the methods described herein include any ink composition that is capable of forming a conductive layer on a target substrate rapidly, ideally at low temperature, and ideally under ambient atmospheric conditions. Such compositions, which will also bereferred to as “conductive inks” or “inks”, include nanoparticulate inks, microparticulate inks, carbon inks, copper sulfate inks, conductive polymer inks, and metal complex conductive inks (or metal-organic decomposition (MOD) inks). Many of these inks are known in the art but have not previously been used for these purposes.
[0039] Accordingly, in some embodiments, the conductive ink composition used in the instant methods is any of the above-described conductive inks.
[0040] In more specific embodiments, the conductive ink composition used in the instant methods is a metal complex conductive ink composition. The metal complex conductive ink composition can comprise any suitable metal, but preferably it comprises silver, copper, palladium, gold, platinum, indium, or nickel. More preferably, the metal complex conductive ink composition comprises silver, gold, or platinum.
[0041] For example, ink compositions prepared from silver metal precursors have been described in PCT International Publication No. WO2013 / 096664A1, which is incorporated herein by reference in its entirety. Further metal complex conductive ink compositions comprising silver metal precursors are described, for example, in PCT International Publication Nos. WO2015 / 160938A1 and WO2023 / 168452A2, in PCT International Application No. PCT / US2023 / 086353, filed December 29, 2023, and in U. S. Application No. 63 / 622,489, filed January 18, 2024, each of which is incorporated herein by reference in its entirety. Metal complex conductive ink compositions comprising copper are described, for example, in PCT International Publication No. W02018 / 118460A1, which is incorporated herein by reference in its entirety. The metal complex conductive inks disclosed in these references typically also comprise a suitable dissolving agent.
[0042] In some embodiments, the metal complex conductive ink composition is a particle-free conductive ink composition. A particle-free conductive ink composition is preferably one that does not include any particles at a diameter of greater than about 10 nm. In some embodiments, a particle-free ink composition is one that has less than about 1% particles, preferably less than about 0.1% particles.
[0043] The conductive ink compositions used in the instant methods preferably possess low viscosity, so that they are compatible with a broad range of application techniques, including slot die coating, spin coating, roll-to-roll printing, including gravure, flexography, rotary screen printing, screen-printing, aerosol jet printing, inkjet printing, airbrushing, Mayer rod coating, flood coating, 3D printing, and electrohydrodynamicprinting. In particular, the inks may be compatible with inkjet printing, dip coating, and spray coating. The conductive structures formed from the ink compositions using the disclosed methods are preferably highly conductive at room temperature and preferably achieve bulk conductivity upon decomposition at mild temperatures (e.g., in some cases at less than about 100 °C). Finally, the ink compositions preferably remain stable at room temperature for months without particle precipitation. They are also preferably stable to the process by which they are applied to the target surface, so they do not form significant amounts of a conductive layer until they are in full contact with the heated target surface.
[0044] As just described, the conductive ink composition of the instant methods preferably have a desired viscosity. In some embodiments, the desired viscosity is obtained using a micro VISC viscometer. In some embodiments, the conductive ink composition has a viscosity from about 50 centipoise to about 1000 centipoise. In some embodiments, the conductive ink composition has a viscosity from about 5 centipoise to about 50 centipoise. In some embodiments, the conductive ink composition has a viscosity from about 10 centipoise to about 40 centipoise. In some embodiments, the conductive ink composition has a viscosity from about 20 centipoise to about 30 centipoise. In some embodiments, the conductive ink composition has a viscosity from about 18 centipoise to about 20 centipoise. In some embodiments, the conductive ink composition has a viscosity of about 18, about 19, or about 20 centipoise. In some embodiments, the conductive ink composition has a viscosity of at least about 5 centipoise, about 10 centipoise, about 20 centipoise, about 30 centipoise, about 40 centipoise, about 50 centipoise, about 60 centipoise, about 70 centipoise, about 80 centipoise, about 90 centipoise, about 100 centipoise, about 200 centipoise, about 300 centipoise, about 400 centipoise, about 500 centipoise, about 600 centipoise, about 700 centipoise, about 800 centipoise, or about 900 centipoise. In some embodiments, the conductive ink composition has a viscosity of at most about 1000 centipoise, about 900 centipoise, about 800 centipoise, about 700 centipoise, about 600 centipoise, about 500 centipoise, about 400 centipoise, about 300 centipoise, about 200 centipoise, about 100 centipoise, about 90 centipoise, about 80 centipoise, about 70 centipoise, about 60 centipoise, about 50 centipoise, about 40 centipoise, about 30 centipoise, about 20 centipoise, or about 10 centipoise.
[0045] In some embodiments, the viscosity of the conductive ink composition is adjusted based upon the amount of dissolving agent used. In some embodiments, the viscosity of the complex is adjusted based upon the type of dissolving agent used. For example, in embodiments where the dissolving agent comprises limonene and terpineol, an increase in the percentage of terpineol in the conductive ink composition can increase the viscosity of the ink. In some embodiments, the viscosity of silver complex can be tuned from less than 5 centipoise with a large proportion of limonene to 50 centipoise with a large portion of terpineol. Unless otherwise indicated, all viscosity values are for samples at room temperature.
[0046] In some embodiments, the ink compositions of the instant methods have a concentration of about 0.1-50 weight percent metal salt of the ink composition. In some embodiments, the ink compositions of the instant methods have a concentration of about 0.1-40 weight percent metal salt of the ink composition. In some embodiments, the ink compositions have a concentration of about 1-30 weight percent metal salt of the ink composition. In some embodiments, the ink compositions have a concentration of about 1-20 weight percent metal salt of the ink composition. In some embodiments, the ink compositions have a concentration of about 1-10 weight percent metal salt of the ink composition. In some embodiments, the ink compositions have a concentration of about 5-15 weight percent metal salt of the ink composition. In some embodiments, the ink compositions have a concentration of about 0.1 weight percent, about 0.2 weight percent, about 0.3 weight percent, about 0.4 weight percent, about 0.5 weight percent, about 0.6 weight percent, about 0.7 weight percent, about 0.8 weight percent, about 0.9 weight percent, about 1 weight percent, about 2 weight percent, about 3 weight percent, about 4 weight percent, about 5 weight percent, about 6 weight percent, about 7 weight percent, about 8 weight percent, about 9 weight percent, about 10 weight percent, about 11 weight percent, about 12 weight percent, about 13 weight percent, about 14 weight percent, about 15 weight percent, about 16 weight percent, about 17 weight percent, about 18 weight percent, about 19 weight percent, or about 20 weight percent metal of the ink composition.
[0047] In some embodiments, the ink compositions of the instant methods have a concentration of at least about 0.1 weight percent, about 0.2 weight percent, about 0.3 weight percent, about 0.4 weight percent, about 0.5 weight percent, about 0.6 weight percent, about 0.7 weight percent, about 0.8 weight percent, about 0.9 weight percent, 1weight percent, about 2 weight percent, about 3 weight percent, about 4 weight percent, about 5 weight percent, about 6 weight percent, about 7 weight percent, about 8 weight percent, about 9 weight percent, about 10 weight percent, about 11 weight percent, about 12 weight percent, about 13 weight percent, about 14 weight percent, about 15 weight percent, about 16 weight percent, about 17 weight percent, about 18 weight percent, about 19 weight percent, or about 20 weight percent metal salt of the ink composition. In some embodiments, the ink compositions have a concentration of at most about 40 weight percent, about 39 weight percent, about 38 weight percent, about 37 weight percent, about 36 weight percent, about 35 weight percent, about 34 weight percent, about 33 weight percent, about 32 weight percent, 31 weight percent, about 30 weight percent, about 29 weight percent, about 28 weight percent, about 27 weight percent, about 26 weight percent, about 25 weight percent, about 24 weight percent, about 23 weight percent, about 22 weight percent, about 21 weight percent, about 20 weight percent, about 19 weight percent, about 18 weight percent, about 17 weight percent, about 16 weight percent, about 15 weight percent, about 14 weight percent, about 13 weight percent, or about 12 weight percent metal salt of the ink composition.
[0048] In some embodiments, the ink compositions of the instant methods have a concentration of about 0.1-50 weight percent metal complex of the ink composition. In some embodiments, the ink compositions of the instant methods have a concentration of about 0.1 -40 weight percent metal complex of the ink composition. In some embodiments, the ink compositions have a concentration of about 1-30 weight percent metal complex of the ink composition. In some embodiments, the ink compositions have a concentration of about 1-20 weight percent metal complex of the ink composition. In some embodiments, the ink compositions have a concentration of about 1-10 weight percent metal complex of the ink composition. In some embodiments, the ink compositions have a concentration of about 5-15 weight percent metal complex of the ink composition. In some embodiments, the ink compositions have a concentration of about 0.1 weight percent, about 0.2 weight percent, about 0.3 weight percent, about 0.4 weight percent, about 0.5 weight percent, about 0.6 weight percent, about 0.7 weight percent, about 0.8 weight percent, about 0.9 weight percent, 1 weight percent, about 2 weight percent, about 3 weight percent, about 4 weight percent, about 5 weight percent, about 6 weight percent, about 7 weight percent, about 8 weight percent, about 9 weight percent,about 10 weight percent, about 11 weight percent, about 12 weight percent, about 13 weight percent, about 14 weight percent, about 15 weight percent, about 16 weight percent, about 17 weight percent, about 18 weight percent, about 19 weight percent, or about 20 weight percent metal complex of the ink composition.
[0049] In some embodiments, the ink compositions of the instant methods comprise an adhesion promoter. Exemplary adhesion promoters are described in PCT International Publication No. WO2023 / 168452A2 and in PCT International Application No.PCT / US2023 / 086353, filed December 29, 2023, the disclosures of which are incorporated by reference herein for all purposes.Dielectric Ink Compositions
[0050] Dielectric ink compositions suitable for use in forming nonconductive layers according to the methods described herein include any ink composition that is capable of forming a nonconductive layer on a target substrate rapidly, ideally at low temperature, and ideally under ambient atmospheric conditions. Such compositions, which will also be referred to as “dielectric inks”, include, for example, an ink comprising any of the dielectric materials described in PCT International Publication Nos. WO2019 / 141833A1, W02020 / 078938A1, W02020 / 078939A1, WO2022 / 117715A1, WO2022 / 184661A1, and WO2022 / 223599A1, the disclosures of which are incorporated herein by reference for all purposes.Curing of the Conductive and Dielectric Layers
[0051] In some embodiments, the conductive ink form a conductive layer on the target substrate without a further processing step, for example if the substrate is heated above a threshold temperature prior to deposition of the conductive ink. In some embodiments, however, the methods include the step of curing or baking the conductive layer at an elevated temperature. The curing or baking step can, for example, remove undesirable volatile components from the conductive layer that may not be fully released during the spray coating or printing process. Such residual agents can include, for example, volatile solvents or other volatile components of the conductive ink. In some cases, such residual agents can compromise the structural or functional properties of the conductive layer, and the curing or baking step may accordingly improve those properties by release of the residual agent. Similar curing steps can also be used to generate dielectric layers from the dielectric inks.
[0052] For example, in some embodiments, the curing step is performed at a temperature of about 250 °C or less. In some embodiments, the curing step is performed at a temperature of about 240 °C or less, about 230 °C or less, about 220 °C or less, about 210 °C or less, about 200 °C or less, about 190 °C or less, about 180 °C or less, about 170 °C or less, about 160 °C or less, about 150 °C or less, about 140 °C or less, about 130 °C or less, about 120 °C or less, about 110 °C or less, about 100 °C or less, about 90 °C or less, about 80 °C or less, or about 70 °C or less. In some embodiments, the curing step is performed using a heat source. Examples of heat sources include an IR lamp, oven, or a heated substrate.
[0053] In some embodiments, the curing or baking step is performed for at least 5 minutes, at least 10 minutes, at least 20 minutes, at least 30 minutes, at least 60 minutes, or even longer. In some embodiments, the curing or baking step is performed for no more than 60 minutes, no more than 30 minutes, no more than 20 minutes, no more than 10 minutes, no more than 5 minutes, or even shorter.
[0054] In some embodiments, the curing step is performed by exposing the conductive or dielectric layer to a light source at a wavelength from about 100 nm to about 1500 nm. In some embodiments, the curing step is performed by exposing the conductive or dielectric layer to a light source such as a Xenon lamp, an IR lamp, or a laser at a wavelength from about 100 nm to about 1000 nm. In some embodiments, the curing step is performed by exposing the conductive or dielectric layer to a light source at a wavelength from about 100 nm to about 700 nm. In some embodiments, the curing step is performed by exposing the conductive or dielectric layer to a light source at a wavelength from about 100 nm to about 500 nm. In some embodiments, the curing step is performed by exposing the conductive or dielectric layer to a light source at a wavelength from about 100 nm to about 300 nm. In some embodiments, the curing step is performed by exposing the conductive or dielectric layer to a light source at a wavelength of about 100 nm, about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, or about 1000 nm.
[0055] In some embodiments, the curing step is performed by a combination of heating the conductive or dielectric layer, for example at any of the above-listed temperatures, and exposing the conductive or dielectric layer to a light source, for example at any of the above-listed wavelengths.
[0056] It will be readily apparent to one of ordinary skill in the relevant arts that other suitable modifications and adaptations to the structures and methods described herein may be made without departing from the scope of the invention or any embodiment thereof. Having now described the present invention in detail, the same will be more clearly understood by reference to the following Examples, which are included herewith for purposes of illustration only and are not intended to be limiting of the invention.EXAMPLESExemplary ink formulations for aerosol jet printing and inkjet printing.Formulation 1
[0057] In this exemplary ink preparation, a silver decanoate isomer mixture (45 wt %) was dissolved in limonene (55 wt %). To this mixture was added a decanoic acid isomer mixture as an acid stabilizer (3 wt %).Formulation 2
[0058] This exemplary ink preparation was the same as Formulation 1, except that a triethoxysilyl-modified poly-1,2-butadiene adhesion promoter was added to 0.5 wt %. Formulation 3
[0059] This exemplary ink preparation comprised pre-made silver nanoparticles (19.8 wt %) dissolved in a mixture of decane (77.2 wt %), hexadecane (2.0 wt %) and dodecylamine (1.0%). The mixture was mixed with a stir bar for 30 min to completely dissolve the silver nanoparticles. After mixing, the mixture was filtered to remove any undissolved components.Formulation 4
[0060] This exemplary ink preparation, a gold precursor (EHAMAuTFA) (20 wt %) was dissolved in toluene (80 wt %). The mixture was vortexed for 1 minute and filtered before printing.Electronic 3-Dimensional Multi-Layer Structures Prepared from Metal Complex Conductive Inks
[0061] Target substrates can be fabricated by direct ink writing (DIW) printing method. The 3-dimensional structure will be generated by DIW method using a particle-free. UV curable metal complex conductive ink in combination with dielectric ink, for example, ona substrate that can be preheated to approximately 150 °C to 200 °C. The metal complex conductive ink is sprayed on the surface of the preheated substrate and is rapidly converted to a metallic film on contact with the heated surface. Film thicknesses of 0.5-2 μm are ideally formed, so that the conductive layer is both sufficiently adhesive to the substrate and sufficiently conductive for the subsequent fabrication steps. The process is performed in an ambient environment. The metallic film formed from the conductive ink can be further cured at an elevated temperature, if desired, to remove any remaining volatile components of the ink and to improve other characteristics of the conductive layer.
[0062] FIG. 1 illustrates steps used in printing process for generating 3-dimensional multi-layer structure. The design steps can be made by computer-aided design (CAD) files that can be easily changed or modified.
[0063] FIGs. 2A-2E graphically illustrates various printing processes with a conductive ink, preferably a metal-organic decomposition (MOD) ink. The printing process can be used to pattern a metal onto the surface of a dimension from 1 μm to meter range. The proposed DIW printing process will have good accuracy and reduced costs compared with the traditional manufacturing processes.
[0064] FIG. 3 graphically illustrates an inkjet printed layer on a flexible substrate in accordance with some aspects of the disclosure.
[0065] FIG. 4 illustrates the micro structured aerosol printed gold sensor on flexible substrate in accordance with some aspects of the disclosure. The disclosed structures and methods have good adhesion characteristics on flexible substrates and high purity and are particularly useful in anti -corrosion applications.
[0066] FIG. 5 graphically illustrates the characteristics of a target surface (substrate) after in-situ UV curing. The UV curing step can remove any remaining volatile components of the ink and thus improve its physical and / or electrical properties of the surface. A further curing or baking step can, for example, remove undesirable volatile components from the substrate that may not be fully released during the spray coating or printing process.
[0067] FIGs. 6A, and 6B show a 3-dimensional printed capacitor structure and the respective structural layers in accordance with some aspects of the disclosure. The dielectric layer (e.g., a PD-L layer) could be deposited using direct ink writing process(DIW) to enable selective deposition of various materials (conductive or dielectric) onto a substrate. DIW process is easy to use, has good accuracy to cover a wide dimensional range, and can have nearly zero waste in the manufacturing process. Further, the use of UV curable dielectric and conductive inks in the DIW fabrication process can enable the creation of 3 -dimensional multi-layer structures at low temperatures and under ambient conditions.
[0068] FIGs. 7A-7C illustrate micro structured printed circuit board (PCB) embodiments and respective printing steps in accordance with some aspects of the disclosure. The dielectric or conductive ink can be applied, for example, by aerosol jet printing, 3D printing, inkjet printing, electrodynamic printing, screen printing, or other printing processes.
[0069] The silver conductive ink used to form conductive layers in the structures shown in FIGs. 6A, 6B, and 7A-7C was Formula 1 (45 wt% silver decanoate, 55 wt% limonene, and 3 wt% versatic acid).
[0070] All patents, patent publications, and other published references mentioned herein are hereby incorporated by reference in their entireties as if each had been individually and specifically incorporated by reference herein.
[0071] While specific examples have been provided, the above description is illustrative and not restrictive. Any one or more of the features of the previously described embodiments can be combined in any manner with one or more features of any other embodiments in the present invention. Furthermore, many variations of the invention will become apparent to those skilled in the art upon review of the specification. The scope of the invention should, therefore, be determined by reference to the appended claims, along with their full scope of equivalents.
Claims
What is Claimed is:
1. A multi-layer structure comprising:a substrate;a first conductive layer on the substrate; anda first dielectric layer on the first conductive layer,wherein the multi-layer structure is prepared by depositing a first conductive ink on the substrate; curing the first conductive ink on the substrate to form the first conductive layer; depositing a first dielectric ink on the first conductive layer; and curing the first dielectric ink on the first conductive layer to form the first dielectric layer.
2. The multi-layer structure of claim 1, wherein the first conductive ink is cured at a temperature of about 21 °C or more.
3. The multi-layer structure of claim 1, wherein the first conductive ink is cured at a temperature of about 300 °C or less.
4. The multi-layer structure of claim 1, wherein the first conductive ink is cured at a temperature of about 21 °C or more without a further processing step.
5. The multi-layer structure of claim 1, wherein the first conductive ink is a metal complex conductive ink.
6. The multi-layer structure of claim 5, wherein the first conductive ink comprises a silver salt.
7. The multi-layer structure of claim 5, wherein the first conductive ink comprises a dissolving agent.
8. The multi-layer structure of claim 5, wherein the first conductive ink comprises an adhesion promoter.
9. The multi-layer structure of claim 1, wherein the first conductive ink is applied by aerosol jet printing.
10. The multi-layer structure of claim 1, wherein the first conductive ink is applied by inkjet printing.
11. The multi-layer structure of claim 1, wherein the first conductive ink is applied to the substrate in an ambient atmosphere.
12. The multi-layer structure of claim 1, wherein the substrate is a non-conducting surface.
13. The multi-layer structure of claim 1, wherein the first conductive layer has a thickness of from about 0.003 pm to about 5 pm.
14. The multi-layer structure of claim 1, wherein the substrate is a glass surface, a metal surface, or a silicon surface.
15. The multi-layer structure of claim 1, wherein the substrate is heated to a threshold temperature prior to depositing the first conductive ink on the substrate.
16. The multi-layer structure of claim 1, further comprising:a second conductive layer on the first dielectric layer; anda second dielectric layer on the second conductive layer.
17. A method for fabricating a multi-layer electronic structure comprising steps of:providing a substrate;depositing a first conductive ink on the substrate;curing the first conductive ink on the substrate to form a first conductive layer; depositing a first dielectric ink on the first conductive layer; andcuring the first dielectric ink on the first conductive layer to form a first dielectric layer.
18. The method of claim 17, wherein the first conductive ink is cured at a temperature of about 21 °C or more.
19. The method of claim 17, wherein the first conductive ink is cured at a temperature of about 300 °C or less.
20. The method of claim 17, wherein the first conductive ink is cured at a temperature of about 21 °C or more without a further processing step.
21. The method of claim 17, wherein the first conductive ink is a metal complex conductive ink.
22. The method of claim 21, wherein the first conductive ink comprises a silver salt.
23. The method of claim 21, wherein the first conductive ink comprises a dissolving agent.
24. The method of claim 21, wherein the first conductive ink comprises an adhesion promoter.
25. The method of claim 17, wherein the first conductive ink is applied by aerosol jet printing.
26. The method of claim 17, wherein the first conductive ink is applied by inkjet printing.
27. The method of claim 17, wherein the first conductive ink is applied to the substrate in an ambient atmosphere.
28. The method of claim 17, wherein the substrate is a non-conducting substrate.
29. The method of claim 17, wherein the first conductive layer has a thickness of from about 0.003 m to about 5 pm.
30. The method of claim 17, wherein the substrate is a glass substrate, a silicon substrate, a thermoplastic substrate, or a printed circuit board substrate.
31. The method of claim 17, wherein the substrate is heated to a threshold temperature prior to depositing the first conductive ink on the substrate.
32. The method of claim 17, wherein the substrate comprises alignment marks, and wherein the substrate is aligned prior to depositing the first dielectric ink on the first conductive layer.
33. The method of claim 17, wherein the first dielectric ink is cured by UV treatment.
34. The method of claim 17, further comprising the steps of:depositing a second conductive ink on the first dielectric layer; andcuring the second conductive ink to form a second conductive layer.
35. The method of claim 34, wherein the second conductive ink is the same as the first conductive ink.
36. The method of claim 34, wherein the substrate comprises alignment marks, and wherein the substrate is aligned prior to depositing the second conductive ink on the first dielectric layer.
37. The method of claim 34, further comprising the steps of:depositing a second dielectric ink on the second conductive layer; andcuring the second dielectric ink to form a second dielectric layer.
38. The method of claim 37, wherein the second dielectric ink is the same as the first dielectric ink.
39. The method of claim 37, wherein the substrate comprises alignment marks, and wherein the substrate is aligned prior to depositing the second dielectric ink on the second conductive layer.
40. A multi-layer structure prepared using the method of any one of claims 17-39.