Dielectric ink compositions and methods of preparation and use

Abstract

Dielectric ink compositions comprising a polymerizable dielectric material are provided. The dielectric ink compositions also include a thermally- or photochemically-activated initiator and optionally an adhesion promoter in a suitable dissolving agent. The dielectric ink compositions can be used to prepare non-conductive layers with highly desirable properties for use in electronic devices. Methods of making the ink compositions and methods of forming nonconductive structures from the ink compositions, including methods where the disclosed compositions are applied to a substrate by various printing techniques, are also provided.

Description

Patent Application 3611-00-022W01DIELECTRIC INK COMPOSITIONS AND METHODS OF PREPARATION AND USECross-reference to Related Application

[0001] This application claims the benefit of U.S. Application No. 63 / 775,945, filed on March 21, 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 dielectric ink compositions and their methods of preparation and use. Further, the present invention relates to a class of dielectric material which can be used for the preparation of dielectric inks in electronic devices. More particularly, the present disclosure relates to improved particle-free ink compositions comprising dielectric materials that are curable by thermal or photochemical treatments.Background of the Invention

[0003] A dielectric material is an electrical insulator that can be polarized by an applied electric field. The electronics, display, and energy industries rely on the production and use of coatings and patterns of dielectric materials to form passivation layers in packaged electronic devices. The dielectric materials show more favorable properties particularly with regard to the requirements in advanced electronic packaging applications such as e.g. wafer level packaging (WLP) as well as for low-dielectric adhesive applications.

[0004] Inks comprising a dielectric material can play a crucial part in manufacturing complex electronic devices. For example, an insulating (z.e., dielectric) material can be prepared in a printable fluid that is formulated to be compatible with a graphic first down layer, as well as with a conductive second down layer. Because the second layer conductive ink may only partially cover the entire printed area of the first layer, a thirdprinted layer should be compatible with graphic printed and dried layers, as well as the printed and dried conductive circuitry of subsequent printed layers, and the unprinted substrate. In many areas, an insulating layer will make direct contact with the graphic printed layers, and the unprinted substrate, as well as that of the conductive printed circuit.

[0005] The vast majority of commercially produced dielectric inks can have significant drawbacks. For example, known inks are typically not UV curable, so they cannot be used to build up significant layer thicknesses. Known inks also typically display high dielectric constant / loss tangent, especially at high working frequencies, and they also typically display low working temperature (typically less than 200 °C). Further, the known inks are not specifically designed for inkjet or aerosol printing methods, so they are unsuited for processing large areas with fine-scale features in short time periods. In particular, the inks typically display high viscosities, which result in poor jettabilities.

[0006] Polymer-based dielectric materials have been disclosed in the prior art. For example, PCT International Publication No. WO201 / 141833A1 provides a class of polymers which can be used as dielectric material for the preparation of passivation layers in electronic devices. Among the polymer compositions arc examples comprising polymerizable compounds wherein the polymerizable groups are selected from groups containing a carbon-carbon double bond or carbon-carbon triple bond, and groups which are suitable for polymerization by a ring-opening reaction.

[0007] PCT International Publication No. WO2018 / 213161A1 relates to flexible and stretchable UV and thermally curable dielectric ink compositions that can be thermo or vacuum formed.

[0008] US Publication No. US2024 / 0254262 provides a class of dielectric polymeric material that is particularly suitable for the manufacturing of electronic devices. The dielectric polymeric material is formed by reacting bismaleimide compounds and shows an advantageous well-balanced profile of favorable material properties. The bismaleimide compounds have an oligomeric structure with an oligoamide extended repeating unit in the middle part of the molecule and maleimide groups at each terminal end of the molecule.

[0009] Despite these and other advances in the field, there continues to be a need for dielectric ink compositions with improved properties.Summary of the Invention

[0010] In some aspects, the techniques described herein relate to dielectric ink compositions including: a polymerizable dielectric material; a thermally- or photochemically-activated initiator; and a dissolving agent suitable for a printing application.

[0011] In some aspects, the techniques described herein relate to methods of making a dielectric ink composition, including the step of dissolving a polymerizable dielectric material and a thermally- or photochemically-activated initiator in a dissolving agent suitable for a printing application.

[0012] In some aspects, the techniques described herein relate to methods of forming a non-conductive structure on a substrate, including the steps of applying a dielectric ink composition of the disclosure on a substrate; and curing the dielectric ink composition.

[0013] In some aspects, the techniques described herein relate to polymerized dielectric films formed by applying a dielectric ink composition of the disclosure to a surface and curing the dielectric ink composition to form a polymerized dielectric film.Brief Description of the Drawings

[0014] FIG. 1 graphically illustrates the characteristics of a target surface (substrate) after in-situ UV curing.

[0015] FIG. 2 illustrates dielectric constant and loss tangent results for dielectric inks as a function of frequency.

[0016] FIG. 3 provides image of Formulation 1 ink composition.

[0017] FIGs. 4A and 4B illustrate the micro structured printed circuit board (PCB) and respective printing steps in accordance with aspects of the disclosure.

[0018] FIG. 5A shows a dielectric ink printing system with an in-situ UV curing; further, FIG. 5B demonstrates optical image along with profile of printed dielectric ink which is cured.

[0019] FIG. 6 demonstrates a 3 -dimensional printed capacitor structure in accordance with aspects of the disclosure.Detailed Description of the Invention

[0020] The dielectric ink compositions disclosed herein have been designed for use in various patterning 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 electrohydrodynamic printing. The ink compositions are particularly well suited for use in aerosol jet printing (AJP) and inkjet printing (UP) applications. For example, the photocurability of the inks and the high process temperatures and low dielectric constants of the resulting printed layers make the inks ideal for the preparation of printed electronics, especially electronics used in high frequency applications. Accordingly, the disclosed inks display at least some of the following advantageous properties: 1) they are low viscosity formulations that can be applied using inkjet or aerosol jet printing methods; 2) they can be cured photochemically, for example using UV radiation, and the curing can be extremely rapid, for example on the order of seconds; 3) the inks result in polymeric layers that display low dielectric constants and low loss tangent in applications up to 100 GHz or more; and 4) the inks have a high working temperature window, in some cases up to 300 °C or more.

[0021] In contrast, dielectric ink compositions known in the prior are not suitable for ultrasonic AJP or IJP, since the printability of the known inks is not good and / or the dielectric layers prepared from the known inks arc only workable at relatively low temperatures (e.g., lower than 200 °C). In addition, dielectric layers prepared from prior / existing dielectric inks do not function well in high frequency applications.

[0022] Accordingly, dielectric ink compositions (also referred to as “non-conductive inks” or “inks”) have been created for printing non-conductive features on electronic devices. Such inks are stable, particle-free, and suitable for a wide range of patterning techniques. In some embodiments, a “particle-free” ink is one that does not include any particles at a diameter of greater than about 10 nm. In some embodiments, a “particle-free” ink is one that has less than about 1% particles, preferably less than about 0.1% particles.

[0023] In one aspect, the disclosure provides dielectric ink compositions comprising:a polymerizable dielectric material;a thermally- or photochemically-activated initiator; anda dissolving agent suitable for a printing application,wherein each of the components of the compositions is described in further detail below.

[0024] In some embodiments, the dielectric ink compositions further comprise an adhesion promoter, as is also described in further detail below.

[0025] In specific dielectric ink composition embodiments, the polymerizable dielectric material comprises an acrylate, methacrylate, maleimide, or 3,4-dimethyl maleimide group, the thermally- or photochemically-activated initiator is a photochemically-activated initiator comprising a benzoyl group, the dissolving agent comprises a substituted benzene, terpene, a terpenoid, or a combination thereof, and the adhesion promoter comprises an alkoxysilyl group.Polymerizable Dielectric Materials

[0026] Dielectric inks play a crucial part in the manufacturing of complex electronic devices. In conventional dielectric ink compositions, common resins, such as epoxy resins, are flaky and hard, which is of limited use in making stretchable interconnects.

[0027] UV-curable acrylate-based formulations have also been widely used in the electronics industry. Typically, UV-curable acrylate-based formulations are used in coating applications and are applied by various coating techniques. Polyamides are commonly used as dielectric materials in the electronics industry and are typically applied either by film lamination or spin-coating liquid polyamides.

[0028] With increasing demands for smaller, flexible and stretchable higher efficiency electric devices, the use of polymerizable dielectric materials that can be cured by photochemical or thermal treatments has become appealing. It is a technical challenge, however, to simultaneously achieve the requirements of electric performance, such as high resistance, thermal stability, good adhesion to a conductive layer, processing performance, and a desired level of bending and forming characteristics.

[0029] The present disclosure generally relates to inks for forming high-performance dielectric layers using aerosol jet or inkjet printing. The thermal- and photo-curability, the high process temperatures, and the low dielectric constants of the resulting printed features are the main characteristics of these inks. The inks are well suited for use in printed electronics, especially those used in high frequency applications.

[0030] The dielectric inks of the disclosure accordingly comprise a polymerizable dielectric material. In accordance with the above description, the polymerizable dielectric material is preferably photochemically or thermally curable and can preferably be dissolved in a suitable dissolving agent at a viscosity suitable for use in aerosol jet and / or inkjet printing applications.

[0031] In some embodiments, the polymerizable dielectric material comprises one or more polymerizable groups. The polymerizable group is prefably a vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane, epoxy, maleimide, 3 -methyl maleimide, 3-ethyl maleimide, 3-propyl maleimide, 3,4-dimethyl maleimide, 3-methyl-4-ethyl maleimide, 3-methyl-4-propoyl maleimide, 3,4-diethyl maleimide, 3-ethyl-4-propoyl maleimide, or 3,4-dipropyl maleimide group. More specifically, the polymerizable group can be an acrylate, methacrylate, maleimide, or 3,4-dimethyl maleimide group. For example, the polymerizable dielectric material can be any of the polymerizable dielectric materials recited in PCT International Publication No. WO2019 / 141833A1, the disclosure of which is incorporated herein by reference in its entirety.

[0032] In some embodiments, the polymerizable dielectric material comprises a polyimide, a polybenzoxazole, a benzocyclobutene, an epoxy group, a silicone group, an acrylate, a nanofilled phenol resin, a siloxane, a fluorinated polymer, or a polynorbornene.

[0033] In some embodiments, the polymerizable dielectric material is a polymerizable compound, represented by Formula (1):P^Sp’- MG-Sp^m-P1Formula (1)wherein:m is an integer from 1 to 60;P1denotes a polymerizable group (P), including any of the above-defined polymerizable groups;Sp1denotes at each occurrence a spacer group (Sp) or a single bond;MG is a rod-shaped mesogenic group, as defined in WO2019 / 141833A1, which is preferably selected from Formula (2):-(A21-Z21)k-A22-(Z22-A23)i- Formula (2)wherein:A21to A23are independently and at each occurrence independently of one another an aryl group, heteroaryl group, heterocyclic group, alicyclic group or cyclic imide group optionally being substituted by one or more identical or different groups L;Z21and Z22are independently and at each occurrence independently from each other, -O-, -S-, -CO-, -COO-, -OCO-, -S-CO-, -CO-S-, -O-COO-, -CO-NR01-, -NR01-CO-, -NR01-CO- NR02, -NR01-CO-O-, -O-CO-NR01-, -OCH2-. -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2, -CH2CH2-, -(CH2)4-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR01-, -CY01=CY°2-, -C°C-, -CFI=CFI-COO-, -OCO-CFI=CFI-, or a single bond; R01and R02each, independently of one another, denote H or alkyl having 1 to 12 C atoms;L is F. Cl, Br, I, -CN, -NO2. -NCO, -NCS, -OCN, -SCN, -C(=O)NRxxRyy, -C(=())()RXX, -C(=O)RXX, -NRxxRyy, -OH, -SFs, or straight chain or branched chain alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with 1 to 20 C atoms, wherein one or more H atoms are optionally replaced by F or Cl, -CN or straight chain or branched chain alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with 1 to 6 C atoms;Rxxand Ry,yindependently of each other denote H or alkyl with 1 to 12 C-atoms; Y01and Y02each, independently of one another, denote H, alkyl having 1 to 12 C atoms, aryl, F, Cl, or CN; and k and I are each and independently 0, 1 , 2, 3 or 4.Thermally- or Photochemically-Activated Initiators

[0034] Thermally- and photochemically-curable formulations have also been widely used in the electronics industry. Typically, UV-curable acrylate-based formulations are used in coating applications and are applied by various coating techniques. Polyamides are commonly used as dielectric materials in the electronics industry and are typically applied cither by film lamination or spin-coating liquid polyamides.

[0035] The dielectric ink compositions of the instant disclosure therefore also comprise a thermally- or photochemically-activated initiator for radical polymerization that can react with the polymerizable dielectric material of the ink to form a passivation layer in a thermal or photochemical curing step, for example after aerosol jet or inkjet printing of the dielectric ink on the surface of an electronic device. The initiator can be activated thermally by exposure to heat or photochemically by exposure to radiation such as UV and / or visible light.

[0036] Exemplary initiators for radical polymerization are: tert-amyl peroxybenzoate, 4,4-azobis(4-cyanovaleric acid), 1 ,r-azobis(cyclohexanecarbonitrile), 2,2’-azobisisobutyronitrile (AIBN), benzoyl peroxide, 2,2-bis (tert-butylperoxy)butane, 1 ,1-bis(te / t-butylperoxy)cyclohexane, 2,5-bis (tert-butylperoxy)-2,5-dimethylhexane, 2,5-bis(te / t-butylperoxy)-2,5-dimethyl-3-hexyne, bis( 1 -(te / t-butylperoxy)- 1 -methylethyljbenzene, l,l-bis(terf-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl hydroperoxide, tert-butyl peracetate, tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, cumene hydroperoxide, cyclohexanone peroxide, dicumyl peroxide, lauroyl peroxide, 2,4-pentanedione peroxide, peracetic acid, and potassium persulfate. Typically, such initiators are radical polymerization initiators that may be thermally activated.

[0037] Further exemplary initiators for radical polymerization are acetophenone, p-anisil, benzil, benzoin, benzophenone, 2-benzoylbenzoic acid, 4,4’-bis(diethylamino)benzophenone, 4,4’-bis(dimethylamino)benzophenone, benzoin methyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin ethyl ether, 4-benzoylbenzoic acid, 2,2’-bis(2-chlorophenyl)- 4,4’,5,5’-tetraphenyl-l,2’-biimidazole, methyl 2-benzoylbenzoate, 2-(l ,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-l ,3,5-triazine, 2-benzyl-2-(dimethylamino)-4’ -morpholinobutyrophenone, (i)-camphorquinone, 2- chlorothioxanthone, 4,4’ -di chlorobenzophenone, 2,2- diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,4- diethylthioxanthen-9-one, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1 ,4-dibenzoylbenzene, 2-ethylanthraquinone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-(2-hydroxycthoxy)-2-mcthylpropiophcnonc, 2-isopropylthioxanthonc, lithium phcnyl(2,4,6-trimethylbenzoyl)phosphinate, 2-methyl-4’-(methylthio)-2-morpholino- propiophenone, 2-isonitrosopropiophenone, 2-phenyl-2-(p-toluenesulfonyl- oxy)acetophenone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. Typically, such initiators are radical polymerization initiators that may be photochemically activated.

[0038] The thermally- or photochemically-activated initiator can, for example, be any of the initiators recited in PCT International Publication No. WO2019 / 141833A1, the disclosure of which is incorporated herein by reference in its entirety.

[0039] In preferred embodiments, the photochemically-activated initiator comprises a benzoyl group. An exemplary benzyoyl-containing initiator is l-(O-acetyloxime)-l-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] ethenone (CAS No. 478556-66-0).

[0040] In some embodiments, UV light sources lamps or UV-lasers can be used, as light in the visible area and laser diodes are other possible options. In preferred embodiments, UV light sources are light sources having a) a single wavelength radiation with a maximum of < 255 nm such as e.g. 254 nm and 185 nm Hg low-pressure discharge lamps, 193 nm ArF excimer laser and 172 nm Xe2 layer, or b) broad wavelength distributionradiation with a wavelength component of < 255 m such as e.g. non-doped Hg low-pressure discharge lamps.Dissolving Agents

[0041] As mentioned above, the instant non-conductive dielectric ink compositions comprise at least one dissolving agent that is capable of dissolving the disclosed dielectric materials, preferably fully dissolving the dielectric materials to generate a particle-free non-conductive dielectric ink composition. Specifically, the dissolving agent acts as a stabilizer and a solvent but is not intended to act as a reducing agent for the dielectric materials.

[0042] The dissolving agent or agents should also be suitable for use in printing applications, in particular aerosol jet and inkjet printing applications. For example, the dissolving agent or agents should dissolve the polymerizable dielectric material and the thermally- or photochemically-activated initiator at a viscosity that is suitable for use in aerosol jet and / or inkjet printing applications. Furthermore, the dissolving agent or agents should be sufficiently volatile that it is completely, or nearly completely, released from the dielectric layer following the printing and curing steps.

[0043] In some embodiments, the dissolving agent has a boiling point of about 250 °C or less. In some embodiments, the dissolving agent has a boiling point of about 200 °C or less. In some embodiments, the dissolving agent has a boiling point of about 100 °C or less. In some embodiments, the dissolving agent has a boiling point of about 220 °C or less, about 210 °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, of about 140 °C or less, of about 130 °C or less, of about 120 °C or less, of about 110 °C or less, of about 90 °C or less, of about 80 °C or less, of about 70 °C or less, of about 60 °C or less, or of about 50 °C or less.

[0044] In some embodiments, the dissolving agent may be selected based on the type of dielectric materials used to make the ink composition. In some embodiments, the dissolving agent may be selected based on the boiling point / tack time for a specific application. In some embodiments, the dissolving agent may be selected based on the type of substrate the ink composition will be applied to for compatibility and wettability issues. For example, for deposition methods such as inkjet printing or e-jet, greater stability is generally preferred, and thus it may be preferable to use a dissolving agent with a higher boiling point.

[0045] In some embodiments, the dissolving agent comprises an alkane hydrocarbon, a carbamate, an alkene, a cyclic hydrocarbon, an aromatic hydrocarbon, an amine, a polyamine, an amide, an ether, an ester, an alcohol, a thiol, a thioether, a phosphine, or a combination thereof.

[0046] In some embodiments, the dissolving agent comprises an organic solvent. In some embodiments, the dissolving agent comprises one or more linear or branched alkane hydrocarbons of length C5-20. For example, the dissolving agent may comprise a pentane, a hexane, a heptane, an octane, a nonane, a decane, an undecane, a dodecane, a tridecane, a tetradecane, a pentadecane, a hexadecane, an octadecane, a nonadecane, or an icosane.

[0047] In some embodiments, the dissolving agent comprises one or more cyclic hydrocarbons of length Ce-io. For example, the dissolving agent may comprise a cyclohexane, a cycloheptane, a cyclooctane, a cyclononane, a cyclodecane, or a decalin. In some embodiments, the dissolving agent comprises an aromatic hydrocarbon. For example, the dissolving agent may comprise benzene, a toluene, a xylene, or a tetralin. In some embodiments, the dissolving agent comprises a xylene.

[0048] In some embodiments, the dissolving agent comprises a substituted benzene, for example an alkoxy-substituted benzene. In some embodiments, the dissolving agent can comprise a methoxy-substituted benzene. In preferred embodiments, the methoxysubstituted benzene is anisole.

[0049] In some embodiments, the dissolving agent comprises a linear ether, a branched ether, or a cyclic ether. In some embodiments, the dissolving agent comprises a linear or branched ether. For example, the dissolving agent may comprise dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, or methyl t-butyl ether. In some embodiments, the dissolving agent comprises one or more cyclic ethers. For example, the dissolving agent can comprise tetrahydrofuran, tetrahydropyran, dihydropyran, or 1,4-dioxane.

[0050] In some embodiments, the dissolving agent comprises an alcohol. In some embodiments, the dissolving agent comprises a primary alcohol, a secondary alcohol, or a tertiary alcohol. In some embodiments, the alcohol comprises a propanol, a butanol, a pentanol, a hexanol, an octanol, or combinations thereof. In some embodiments, the alcohol comprises 1-propanol, 2-propanol, l-methoxy-2-propanol, 1 -butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1 -hexanol, 2-hexanol, 3-hexanol, 1 -octanol, 2-octanol, 3-octanol, tetrahydrofurfuryl alcohol, cyclopentanol, terpineol, or a combination thereof.

[0051] In some embodiments, the dissolving agent comprises a ketone. More specifically, in some embodiments, the dissolving agent comprises actylacetone.

[0052] The dissolving agent used in the ink compositions is ideally suitable for use at an industrial scale in mass production. In some embodiments, it can therefore be advantageous for the dissolving agent to be non-toxic and / or to be less damaging to the environment than is the case for many commonly-used organic solvents. In some embodiments, it can be advantageous for the dissolving agent to have a higher flash point than is the case for many commonly-used organic solvents. In some embodiments, it can be advantageous for the dissolving agent to be subject to fewer regulations than is the case for many commonly-used organic solvents. For example, aromatic hydrocarbons such as xylene, toluene, mesitylene, and the like, are highly regulated in most industrial countries. The use of alternatives to these solvents can therefore be advantageous. In addition, conductive inks formulated from aromatic hydrocarbons can have flash points that are lower than 60°C and that are therefore not typically acceptable in mass production environments. Accordingly, in some embodiments, the dissolving agent of the instant conductive ink compositions docs not comprise an aromatic hydrocarbon.

[0053] In some embodiments, the dissolving agent comprises a terpene, a terpenoid, or a combination thereof. For example, in some embodiments, the dissolving agent comprises a pinene, a limonene, in particular a D-limonene, a terpineol, or a combination thereof. In preferred embodiments, the dissolving agent comprises limonene. In other preferred embodiments, the dissolving agent comprises terpineol. In still other preferred embodiments, the dissolving agent comprises a combination of limonene and terpineol.

[0054] Not all terpenes and terpenoids are suitable for use in the non-conductive dielectric ink compositions of the instant disclosure. For example, in some embodiments, the instant dissolving agent does not comprise alpha-terpinene, gamma-terpinene, terpinolene, or terpene-4-ol. Alternatively, or in addition, in some embodiments, it can be advantageous for the dissolving agent to be a purified form of the dissolving agent. For example, in some embodiments, the dissolving agent is a purified terpineol, a purified limonene, or a combination of a purified terpineol and a purified limonene. A purified dissolving agent is understood to be at least 95% pure, at least 97% pure, at least 98% pure, at least 99% pure, or even more pure.

[0055] In some embodiments, the dielectric ink composition comprises two or more dissolving agents. In some embodiments, the volume ratio of two dissolving agents in the dielectric ink is about 1 to about 1 of the first dissolving agent to the second dissolving agent. In some embodiments, the volume ratio of two dissolving agents in the conductive ink is about 2 to about 1 of the first dissolving agent to the second dissolving agent. In some embodiments, the volume ratio of two dissolving agents is about 3 to about 1 of the first dissolving agent to the second dissolving agent. In some embodiments, the volume ratio of two dissolving agents is about 4 to about 1 of the first dissolving agent to the second dissolving agent.

[0056] In some embodiments, the flash point of the dielectric ink composition can be varied by varying the volume ratio of two or more dissolving agents in the dielectric ink. For example, in some embodiments, the flash point of the dielectric ink composition is increased by increasing the relative amount of a dissolving agent that has a higher flash point compared to a dissolving agent that has a lower flash point. More specifically, in some embodiments, the flash point of the dielectric ink composition is modulated by varying the ratio of a limonene to a terpineol in the conductive ink composition. Even more specifically, the flash point of the dielectric ink composition can be decreased by increasing the ratio of a limonene to a terpineol in the conductive ink composition.

[0057] As mentioned above, the dissolving agent or agents used in any of the disclosed dielectric ink compositions should be suitable for use in printing applications, in particular for use in aerosol jet and inkjet printing applications. Such suitability can in some cases be determined by trial and error. Some of the above-described dissolving agents have been demonstrated to be suitable for use in printing applications with conductive ink compositions, for example as described in PCT International Publication Nos.WO2015 / 16Q938A1, WO2023 / 168452A2, and WO2024 / 145547A1. the disclosures of which are incorporated herein by reference in their entireties. Some suitable dissolving agents are described in the ink formulations exemplified below.Adhesion Promoters

[0058] In some dielectric inks, it can be advantageous to include an optional adhesion promoter to improve the surface properties of the passivation layer prepared from the polymerizable dielectric material in the ink. The adhesion promoter can be any suitable adhesion promoter, as would be understood by those of ordinary skill in the art. Forexample, the adhesion promoter can be any of the adhesion promoters disclosed in PCT International Publication No. WO2023 / 168452A1, the disclosure of which is incorporated herein by reference in its entirety.

[0059] In some embodiments, the adhesion promoter comprises an alkoxysilyl group.

[0060] In specific embodiments, the adhesion promoter is N- [3 -(trimethoxy silyl)propyl] ethylenediamine (CAS number 1760-24-3).Applications of the Dielectric Ink Compositions

[0061] The dielectric ink compositions of the instant disclosure can be used in various printing applications, 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, dispenser, and electrohydrodynamic printing. In particular, the inks can be used in aerosol jet printing and inkjet printing.

[0062] In some embodiments, the polymerizable dielectric material is completely dissolved in at least one dissolving agent to prepare the dielectric ink. A thermally- or photochemically-activated initiator, for example any of the initiators described above, is also included in the dissolving agent. An optional adhesion promoter, for example any of the adhesion promoters described above, can also be included in the dissolving agent to form the dielectric ink.

[0063] fhe fully dissolved polymerizable dielectric material, and any of the other components of the dielectric ink can be compatible with many nonpolar polymer substrates, glasses, and ceramic substrates where polar complexes do not wet particularly well. In some embodiments, the dielectric ink composition comprising the polymerizable dielectric material and other ink components can be applied to a polymer substrate, for example a flexible polymer substrate, such as a polyimide (PI) substrate, for example Kapton. In some embodiments, the dielectric ink composition comprising the polymerizable dielectric material and other ink components can be applied to a nonpolar polymer substrate. In some embodiments, the dielectric ink composition can be applied to a glass substrate. In some embodiments, the dielectric ink composition comprising the polymerizable dielectric material and other ink components can be applied to a ceramic substrate.

[0064] Furthermore, elastomers and 3D substrates with specifically non-planar topography can be used in conjunction with the printed structures. In some embodiments, the dielectric ink composition comprising the polymerizable dielectric material and other ink components can be applied to an elastomer. In some embodiments, the dielectric ink composition comprising the polymerizable dielectric material and other ink components can be applied to a 3D substrate.

[0065] In some embodiments, the dielectric ink compositions of the instant disclosure can be applied to an epoxy substrate, such as, for example, an epoxy molding compound (EMC) substrate or the like. In some embodiments, the epoxy substrate has residual mold release on the surface of the substrate.

[0066] In some embodiments, the dielectric ink composition of the disclosure has a desired viscosity. In some embodiments, the desired viscosity is obtained using a micro VISC viscometer. In some embodiments, the dielectric ink composition has a viscosity from about 50 centipoise to about 1000 centipoise. In some embodiments, the dielectric ink composition has a viscosity from about 5 centipoise to about 50 centipoise. In some embodiments, the dielectric ink composition has a viscosity from about 10 centipoise to about 40 centipoise. In some embodiments, the dielectric ink composition has a viscosity from about 20 centipoise to about 30 centipoise. In some embodiments, the dielectric ink composition has a viscosity from about 18 centipoise to about 20 centipoise. In some embodiments, the dielectric ink composition has a viscosity of about 18, about 19, or about 20 centipoise. In some embodiments, the dielectric 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 dielectric 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.

[0067] It will be readily apparent to one of ordinary skill in the relevant arts that other suitable modifications and adaptations to the compositions 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 comprising a polymerizable dielectric material, a photochemically-curable initiator, and an adhesion promoter.Formulation 1

[0068] In one exemplary ink preparation, a polymerizable dielectric material in resin form was dissolved in an anisole solvent to lower viscosity and ensure aerosol atomization compatibility. The dielectric ink has high stability during the ultrasonic atomization process due to the low vapor pressure of the anisole solvent.

[0069] The dielectric ink of Formulation 1 also contains a UV-curable initiator and an adhesion promoter. Specifically, the UV-curable initiator in Formulation 1 is 1-(O-acetyloxime)-l-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] ethenone, and the adhesion promoter is N-[3-(trimethoxysilyl)propyl] ethylenediamine.Formulation 2

[0070] This dielectric ink preparation is the same as Formulation 1, except that the dissolving agent comprises a terpene, a terpenoid, or a combination thereof.Properties of the exemplary ink formulations and their use in forming non-conductive dielectric structures

[0071] All of the above-described ink formulations yielded clear ink solutions. The ink formulations could all be printed on suitable substrates using standard inkjet technologies and cured to form polymerized dielectric films at relatively low temperatures.

[0072] FIG. 1 graphically illustrates the characteristics of a target surface (substrate) after in-situ UV curing.

[0073] FIG. 2 illustrates dielectric constant and loss tangent results for dielectric inks as a function of frequency.

[0074] FIG. 3 provides an image of the Formulation 1 ink composition.

[0075] FIGs. 4A and 4B illustrate a micro structured printed circuit board (PCB) and respective printing steps in accordance with aspects of the invention. The dielectric and conductive ink layers can be applied by aerosol jet printing, 3D printing, inkjet printing, electrodynamic printing, screen printing, or other printing processes.

[0076] FIG. 5A shows a dielectric ink printing system with an in-situ UV curing; further, FIG. 5B demonstrates optical image along with profile of printed dielectric ink which is cured.

[0077] FIG. 6 shows a 3-dimensional printed capacitor structure that was prepared in accordance with the compositions and methods of the disclosure. The dielectric host layer (PDF) could be deposited using different printing processes such as direct ink writing aerosol jet printing, 3D printing, inkjet printing, electrodynamic printing, screen printing to enable selective deposition of various materials (conductive or dielectric) onto a substrate. The printing processes are easy to use, have good accuracy to cover a wide dimensional range, and result in little or no waste in the manufacturing process.

[0078] All patents, patent publications, and other published references mentioned herein arc hereby incoiporatcd by reference in their entireties as if each had been individually and specifically incorporated by reference herein.

[0079] 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 dielectric ink composition comprising:a polymerizable dielectric material;a thermally- or photochemically-activated initiator; anda dissolving agent suitable for a printing application.

2. The dielectric ink composition of claim 1 , wherein the polymerizable dielectric material comprises a vinyloxy. acrylate, methacrylate fluoroacrylate, chloroacrylate, oxetane, epoxy, maleimide, 3-methyl maleimide, 3-ethyl maleimide, 3-propyl maleimide, 3,4-dimethyl maleimide, 3-methyl-4-ethyl maleimide, 3-methyl-4-propoyl maleimide, 3,4-diethyl maleimide, 3-ethyl-4-propoyl maleimide, or 3,4-dipropyl maleimide group.

3. The dielectric ink composition of claim 2, wherein the polymerizable dielectric material comprises an acrylate, methacrylate, maleimide, or 3,4-dimethyl maleimide group.

4. The dielectric ink composition of claim 1 , wherein the thermally- or photochemically-activated initiator is a photochemically-activated initiator.

5. The dielectric ink composition of claim 4, wherein the photochemically-activated initiator comprises a benzoyl group.

6. The dielectric ink composition of claim 5, wherein the photochemically-activated initiator is l-(O-acetyloxime)-l-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] ethenone.

7. The dielectric ink composition of claim 1, further comprising an adhesion promoter.

8. The dielectric ink composition of claim 7, wherein the adhesion promoter comprises an alkoxysilyl group.

9. The dielectric ink composition of claim 8, wherein the adhesion promoter is N-[3-(trimethoxysilyl)propyl] ethylenediamine.

10. The dielectric ink composition of claim 1, wherein the dissolving agent comprises a substituted benzene, terpene, a terpenoid, or a combination thereof.

11. The dielectric ink composition of claim 10, wherein the terpene is a purified terpene or the terpenoid is a purified terpenoid.

12. The dielectric ink composition of claim 10, wherein the terpenoid is a terpineol.

13. The dielectric ink composition of claim 10, wherein the dissolving agent comprises a limonene and a terpineol.

14. The dielectric ink composition of claim 13, wherein the limonene is a purified limonene and the terpineol is a purified terpineol.

15. The dielectric ink composition of claim 10, wherein the substituted benzene is an alkoxy-substituted benzene.

16. The dielectric ink composition of claim 15, wherein the alkoxy-substituted benzene is a methoxy-substituted benzene.

17. The dielectric ink composition of claim 16. wherein the methoxy-substituted benzene is anisole.

18. The dielectric ink composition of claim 1, wherein the dielectric ink composition has a viscosity from about 1 centipoise to about 1000 centipoise.

19. The dielectric ink composition of claim 1, wherein the polymerizable dielectric material is stable to an ultrasonic atomization process.

20. The dielectric ink composition of claim 1, wherein the dielectric ink composition is particle free.

21. The dielectric ink composition of claim 1, wherein a dielectric layer formed from the dielectric ink composition is workable at a temperature of about 200 °C or more.

22. The dielectric ink composition of claim 1, wherein the dielectric ink composition has a ratio of polymerizable dielectric material to dissolving agent weight ratio of about 7 to 3.

23. A method of making a dielectric ink composition, comprising step ofdissolving a polymerizable dielectric material and a thermally- or photochemically-activated initiator in a dissolving agent suitable for a printing application.

24. The method of claim 23, wherein the thermally- or photochemically-activated initiator is l-(O-acetyloxime)-l-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] ethenone.

25. The method of claim 23, further comprising the step of dissolving an adhesion promoter in the dissolving agent.

26. The method of claim 25, wherein the adhesion promoter is N-[3-(trimethoxysilyl)propyl] ethylenediamine. .

27. The method of claim 23, wherein the dissolving agent comprises a terpene, a terpenoid, or a combination thereof.

28. The method of claim 27, wherein the terpene is a purified terpene or the terpenoid is a purified terpenoid.

29. The method of claim 27, wherein the terpene is a pinene or a limonene.

30. The method of claim 27, wherein the terpenoid is a terpineol.

31. The method of claim 23, wherein the dissolving agent comprises a limonene and a terpineol.

32. The method of claim 31 , wherein the limonene is a purified limonene and the terpineol is a purified terpineol.

33. The method of claim 23, wherein the dielectric ink composition has a viscosity from about 1 centipoise to about 1000 centipoise.

34. The method of claim 23, wherein the polymerizable dielectric material is stable to ultrasonic atomization.

35. The method of claim 23, wherein the dielectric ink composition is particle free.

36. The method of claim 23, wherein a dielectric layer formed from the dielectric ink composition is workable at a temperature of about 250 °C or more.

37. The method of claim 23, wherein the dielectric ink composition is further diluted with an anisole solvent.

38. The method of claim 23, wherein the dielectric ink composition has a ratio of polymerizable dielectric material to dissolving agent weight ratio of about 7 to 3.

39. A method of forming a non-conductive structure on a substrate, comprising the steps of:applying the dielectric ink composition of any one of claims 1-22 on a substrate; and curing the dielectric ink composition.

40. The method of claim 39, wherein the applying step is a printing step.

41. The method of claim 40, wherein the printing step is a jet printing step.

42. The method of claim 41, wherein the jet printing step is an aerosol jet printing or inkjet printing step.

43. The method of claim 39, wherein the curing step comprises a thermal treatment step.

44. The method of claim 39, wherein the curing step comprises a photochemical treatment step.

45. A polymerized dielectric film formed by applying the dielectric ink composition of any one of claims 1-22 to a surface and curing the dielectric ink composition to form a polymerized dielectric film.

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