CN117043282A

CN117043282A - Compositions and methods for improving durability of electrically insulating and water repellent gel coat systems

Info

Publication number: CN117043282A
Application number: CN202180093066.8A
Authority: CN
Inventors: 贾斯汀·克莱恩加特纳; 斯鲁蒂·巴拉苏布拉马尼亚安; 利亚姆·道尔; 塞德里克·维里; 茱莉亚·赵
Original assignee: Yake Nano Co
Current assignee: Yake Nano Co
Priority date: 2020-12-04
Filing date: 2021-12-03
Publication date: 2023-11-10

Abstract

A composition for forming a conformal gel coat to protect a substrate from various environmental hazards is disclosed, wherein the composition includes at least one film former, at least one additive, and optionally at least one solvent. The composition is deformable, flowable, electrically insulating, and free of fluorine when applied as a coating. Gel coats, methods of applying such coats to substrates, and coated substrates are also disclosed. Non-limiting examples of such substrates include printed circuit boards, assembled electronic devices, or automotive parts.

Description

Compositions and methods for improving durability of electrically insulating and water repellent gel coat systems

Cross Reference to Related Applications

The present application claims priority from U.S. provisional application No. 63/121,747, filed on month 4 of 2020, and U.S. provisional application No. 63/240,533, filed on month 9 of 2021, both of which are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates generally to gel state coatings that form protective coatings on substrates and methods of making the same. The present disclosure also relates to compositions for preparing such coatings, and methods of applying such coatings to desired substrates, which may include electronic devices such as printed circuit boards.

Background

Electronic devices are composed of conductive and insulating components that can be adversely affected by exposure to harsh environments. Exposure to liquids such as water will typically cause corrosion or shorting of these components, which will ultimately destroy the function of the electronic device. Furthermore, as such devices become more complex with increased functionality, they are being used in more hazardous environments, such as humidity, corrosive gases, and atomized or bulk liquids, which may reduce the functionality of the device.

When exposed to these environments, electronic devices can fail because the conductive medium can provide a path for current from the component under bias. Most of these faults manifest as corrosion of the electronic components or failure of the component's performance. In addition to failure of the component itself, the conforma coating may also fail due to these difficult conditions due to chemical degradation, which ultimately results in loss of insulation properties.

Thus, durable electrically insulating coatings are becoming a more common form of protection for such devices. Conventional coatings need to mask certain components to ensure that current flow through the connector, test point or ground contact is not inhibited. This process is expensive and time consuming, which adversely affects the overall electronic device manufacturing process.

Conventional conforma coatings are intended to improve their durability by increasing their mechanical strength. Furthermore, conventional conforma coating chemistry use relies on the formation of highly crosslinked networks that are not easily deformable. This makes the coating harder and stiff, which requires compromises (e.g., masking or selective application of certain components) during the electronic device manufacturing process.

Thus, there is a need for a coating that exhibits improved functional durability, allowing it to perform its function over the life of the device, while also retaining the ability to deform and flow. Due to the improved functional durability, the coatings of the present disclosure may be used in a variety of applications when applied to a variety of devices or substrates, such as in the automotive, household and industrial appliances, consumer electronics, aerospace, military and chemical industries, to protect the devices or substrates from a variety of environments. Non-limiting examples of potential uses include coatings and methods that allow electronic devices to be protected from harsh environments and contaminants, such as particles including dust and dirt, and liquids including water and body fluids. Furthermore, there is a need for a coating that can be applied to, for example, a printed circuit board without the need for masking components prior to application. There is also a need for a durable, deformable, and flowable coating that can cover the entire printed circuit board without inhibiting the function of the device.

Disclosure of Invention

In view of the foregoing, compositions for forming durable gel-state coatings to protect devices or substrates, methods of making such coatings, and methods of using such coatings, as well as devices and substrates protected with such coatings, are disclosed.

In one embodiment, a composition for forming a conformal gel coating to protect a substrate from various environments is disclosed, the composition comprising: at least one film forming agent; and at least one additive and optionally at least one solvent, wherein the composition is deformable, flowable, electrically insulating, and free of fluorine when applied as a coating.

Also disclosed is a conformal gel coating for protecting electronic components from various environmental hazards, the coating comprising: at least one film forming agent; and at least one additive and optionally at least one solvent, wherein the gel coat is deformable, flowable, electrically insulating, and fluorine-free.

In another embodiment, a method of treating an electronic device with a gel coat is disclosed, the method comprising: a gel coat is applied to the electronic device, the gel coat comprising a film former and an additive, the coating composition optionally further comprising at least one solvent, dye, pigment, or combination thereof.

In yet another embodiment, various devices or substrates are disclosed on which the coating is applied. These devices or substrates may include automotive parts or printed circuit boards having gel state coatings as described herein. The gel state coating described herein is made from a composition comprising: at least one film former and at least one additive that improves at least one property of the coating.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a flow chart illustrating a representative Antioxidant (AO) addition mechanism according to the disclosed embodiments.

Fig. 2 is a schematic diagram showing a surface insulation resistance measuring device.

Fig. 3 shows a schematic diagram demonstrating migration of additives from the coating to the coating/substrate interface to prevent degradation of the coating or substrate.

Fig. 4 shows a schematic diagram demonstrating migration of additives from the coating to the coating/air interface to prevent degradation of the coating or substrate.

Fig. 5 shows a schematic of the stepwise application of various additives.

Fig. 6 shows a schematic diagram demonstrating migration of additives from an external environment that may affect coating performance to target specific components.

Fig. 7 shows a schematic diagram demonstrating migration of additives from the coating to the coating/air interface to alter mechanical or diffusion properties at the interface.

Detailed Description

As used herein, "conformal coating" refers to a film that follows the contours of a substrate (such as a printed circuit board or component thereof) on which the conformal coating is applied in a continuous manner without cracking or opening. The conforma coatings described herein protect the substrate (such as an electronic circuit) from the environment and liquids or particles (including water, sweat or other moisture, dirt and dust, and chemicals).

As used herein, "film former" refers to a material that is capable of forming a coherent continuous film when applied to a solid surface. The film forming agents described herein are typically used in the form of an organic or aqueous solution or dispersion comprising an organic or aqueous solvent that allows the film forming material to form a film upon evaporation of the solvent.

As used herein, "gel" or "gel state" refers to a material or composite that forms an internal network due to chemical cross-linking and/or physical association between constituent components. The gel coats exhibit non-newtonian, viscoelastic, viscoplastic and/or elastohydroplastic flow properties.

As used herein, "deformation" or "deformability" refers to the ability of a gel to strain (e.g., stretch, bend, etc.) under compressive, tensile, or shear stresses that typically occur during assembly of an electronic device or within the temperature ranges typically seen during processing of an electronic device.

As used herein, "flow" or "flowability" refers to the ability of a gel to behave like a fluid, undergoing a steady rate of shear deformation under the application of a shear stress.

As used herein, "non-newtonian fluid" or a form thereof refers to a fluid that does not follow newtonian law of viscosity (e.g., a fluid whose viscosity may vary based on an applied stress or force). The non-newtonian behavior exhibited by the resulting coating is described by the non-linear relationship between the shear stress of the coating and the presence of shear rate or yield stress. Non-newtonian fluids include single-phase or multi-phase fluids that exhibit non-newtonian behavior. It may also comprise single or multiple components. Non-newtonian fluids are sometimes referred to as complex fluids. In one embodiment, the non-newtonian fluid is viscoelastic.

As used herein, "viscoelastic" refers to a material that exhibits both viscous and elastic properties when subjected to deformation (i.e., the material stores and dissipates energy during periodic/cyclical oscillatory shear deformation). This is typically reported as a non-zero measurable value of storage modulus G' and loss modulus g″.

As used herein, "viscoplasticity" refers to the inelastic behavior of a material, wherein the material undergoes unrecoverable deformation when a critical load level (referred to as yield stress) is reached. The main difference between viscoplastic and viscoelastic materials is the presence of yield stress. The viscoelastic material has a yield stress below which it will not flow, while the viscoelastic material will deform and flow under the application of any limited shear stress.

As used herein, "elastoplastic" refers to a broad class of materials, such as the gel coats described in this patent, that exhibit elastic, viscous, and plastic response properties under application of varying levels of shear stress or strain. Below a critical stress (commonly referred to as yield stress), the material does not undergo steady flow, but rather transient deformation, where some of the strain is elastically accumulated and some of the energy is dissipated through plastic (irreversible) deformation. When the critical load level is reached (i.e., the yield stress is exceeded), the material begins to flow like a liquid, but still exhibits viscoelastic energy (i.e., it has measurable values of elastic modulus G' and loss modulus G "), as some of the initial deformation is stored elastically and some of the external work applied to the material is dissipated viscously. When the applied load is removed, the elasto-viscoplastic response can be distinguished in the rheometer by partial (i.e., elastic) rebound or unloading, but some irreversible deformation is accumulated due to the plastic nature of the material.

As used herein, "durability" refers to the ability of a coating material to retain its functional properties (e.g., electrical insulation, hydrophobicity, appearance, morphology, and physical and chemical properties, etc.) even after exposure to various environmental stresses. The change in coating properties may be caused by a variety of stresses including, but not limited to: continuous exposure to heat, repeated and intermittent exposure to extreme temperatures, low temperature exposure, high temperature and/or high humidity exposure, salt spray exposure, hazardous or corrosive gas exposure, UV exposure and other chemical exposure. These stresses can cause damage to the coating material including, but not limited to, cracking, oxidation, chain scission, radical crosslinking, phase separation, phase transformation, coating flow, browning, delamination, blistering, and the like.

Industry standard tests for evaluating the durability of a conformal coating to meet lifecycle requirements are set by the supplier of the electronic components, the company that assembles the electronic components or PCBs into consumer or automotive equipment, or a third party organization that governs how the conformal coating should be evaluated. Some of these industry standard tests include the company engineering test program of Ford automobile company, the test program of popular VW 80000 electrical and electronic components in automobiles, the qualification of BMW group Standard 95011-5 conforma coating in automobiles, IPC-CC-830C and MIL-STD-810G.

As used herein, "solvated coating" refers to a coating that contains a solvent to aid in its spreading when applied to a substrate, such as to a composition that still contains a solvent. If "solvated" or any form thereof is not used in combination with "coating", the coating is considered to be a dry coating on a substrate or device, e.g., without solvent.

As used herein, "electrically insulating" refers to the property of a material to provide resistance to electrical current. For example, in one non-limiting embodiment, when a gel-state coating is applied to an active ingredient under bias, the coating provides a resistance of greater than 103 ohms or a dielectric breakdown voltage of greater than 1.5 kV/mil.

In one embodiment, the gel state coating comprises a composition that exhibits both viscous and elastic properties. Unlike purely elastic materials, viscoelastic materials will flow like a viscous liquid under load, but will retain the elastic properties of a solid when not under load. Viscoelastic properties have been well studied and the behaviour of viscoelastic materials is known in the art.

In another embodiment, the gel state coating comprises a composition that exhibits elasto-viscoplastic properties. Unlike viscoelastic materials, elastoplastic materials have a critical load level (i.e., yield stress) below which the elastoplastic material will not flow. Elastoplastics has been well studied and the behaviour of elastoplastic materials is known in the art. The elastic and plastic properties associated with the disclosed compounds allow the material to resist liquid contamination and deformation of the material due to physical forces (e.g., gravity), and the viscous properties allow the material to redistribute under stress over time, such as displacement or even coverage of a surface when a force is applied.

Thus, the properties of the gel state coating make it advantageous for use as a coating on electronic devices. Desirable film formers include materials that adhere or adsorb to the electronic device surface to hold the film (typically in the range of nanometers to hundreds of microns). Thicker films can be obtained when the fluid exhibits a yield stress.

The use of gel state coatings can achieve benefits not present with conventional conforma or vacuum coatings. The tacky or plastic nature of the film former may eliminate the need to mask certain components prior to application of the electronic device. Typically, certain components (e.g., connectors and ground traces) are masked for allowing current to flow through the masked areas in the coating. In contrast, when the component is introduced into an electronic device, the gel-state coating exhibits viscoplastic properties by flowing or deforming. The flow or deformation of the gel coat allows the assembly to be connected to an electronic device without interference. The gel state coating will exhibit non-newtonian, viscoelastic, viscoplastic or elastohydroplastic properties. Masking of the component is not required as current will be delivered to the component, however, masking may still be performed if desired.

In alternative embodiments, the film former capable of imparting various mechanical properties to the coating may be comprised of polyamides, polynitriles, polyacrylamides, polycarbonates, polysulfones, polyterephthalates, polysulfides, or combinations thereof. The film former may have a unique polymer topology including linear polymers, cyclic polymers, branched polymers, hyperbranched polymers, grafted polymers, star polymers, bottle brush polymers (bottlebrush polymer), gels with various branched functionalities, or combinations thereof. Alternative embodiments may be made from homopolymers, copolymers of two or more monomers, polymer blends, interpenetrating polymer networks of one or more polymer or copolymer types. The copolymers may be block, statistical, random or alternating copolymers. Furthermore, alternative embodiments of film formers may be made from loosely crosslinked polymer networks (i.e., where gel properties or elastoplastic flow properties are maintained) that contain covalent bonds, dynamic bonds (hydrogen bonds, metal-organic coordination, pi-pi stacking, etc.), polymer entanglement, or combinations of these types. All types of crosslinking may occur before or after the composition is applied to the substrate.

In one embodiment, a composition for forming a coating having improved properties under extreme conditions, such as high and low temperatures, under UV light exposure, high humidity environments, corrosive salt-containing environments, environments with hazardous or corrosive gas mixtures, and sustained properties for long-life periodic products such as automobiles is described.

For example, in one embodiment, conventional coating systems known to degrade when exposed to catalytically active metals may be enhanced by the addition of metal deactivators and antioxidants. The passivating agent and antioxidant concentrations are selected based on the rate of decomposition of the gel coat and the exposed area of the catalytically active metal. The passivating agents and antioxidants are also selected for their relative affinities for the catalytically active metals and their solubilities in the gel coat. Additionally, the passivating agent and the antioxidant may be selected such that they preferentially migrate from the coating body to the interface. The catalytically active metal initiates the decomposition of the coating by generating free radicals. The passivating agent isolates the catalytically active metal from other components of the coating. The primary and secondary antioxidants neutralize the free radicals. Additional additives (e.g., acid scavengers) may be added to inhibit the adverse radical neutralization byproducts generated by the primary and secondary antioxidants.

Previous electrically insulating gel coats did not contain stabilizers to increase durability of the formulation. Accordingly, the present invention addresses the problems and deficiencies of the prior compositions. In one embodiment, the passivation component is disclosed as being applied to the metal substrate of the first layer prior to the application of the second layer of gel coat. In another embodiment, a method of applying a gel coat to a plate in a first layer, followed by an antioxidant-rich layer is disclosed. Combinations of these embodiments may also be used.

The method of formulating additives into gel coat systems by various unit operations, determining the nature of the additives, the amount of additives, is a non-limiting way of the present disclosure as opposed to previous methods.

The nature of the additives formulated into the coating directly affects the durability of the coating. Special additive combinations are required to prevent chemical and mechanical degradation of the coating itself and to protect the underlying substrate. For example, a metal substrate in contact with the coating may catalyze degradation of the coating, resulting in poor electrical insulation properties. In this case, a proprietary combination of metal deactivators shielding the metal/coating interface to protect the metal and primary and secondary antioxidants of the protective coating is required.

Based on the environment to which the electronic component is exposed, proprietary additive formulations can address various failure mechanisms of both the coating and the active substrate. As shown in fig. 5, the passivating agent formulated into the coating may migrate to the metal/coating interface to inhibit catalytic degradation of other components in the coating. The present application relates to selecting suitable additives so that they are capable of migrating from the bulk phase to the interface in order to strengthen the interface so that the coating retains its integrity. Primary antioxidants formulated into the coating can quench any free radicals formed as a result of exposure to the reactive metal or exposure to the environment. The secondary antioxidant formulated into the coating will further deactivate any by-products of the primary antioxidant that react with the free radicals. The present application relates to determining a proper proprietary mixture of additives based on the electronic device and its environment that remains functional while maintaining the deformability of the coating.

Similar to designing a specific additive based on environmental performance requirements, methods of designing coating deformability are also presented in the present application. For example, in order to make a connection by a coating, the coating must be designed to have sufficient ductility in the normal, tensile and compressive directions and to exhibit elastohydroplastic flow properties. The coating may be designed to have a pencil hardness of less than 6B. The storage and loss modulus of the coating in the shear and tensile directions may be less than 106Pa at 25℃when measured at a frequency of 1-100 rad/s. At a temperature of less than 10 in the shear and tensile directions at 25 DEG C ⁴ The coating can yield between 1 and 100rad/s when the yield stress of Pa is deformed.

In one embodiment, a tailored additive formulation is disclosed that improves the performance of existing coatings. For example, if the gel coat degrades at higher temperatures, the present disclosure relates to a change in composition or a method of incorporating an additive that increases the durability of the coating by allowing the coating to resist degradation. Higher temperatures may lead to oxidative degradation of the coating, which will alter its chemical structure and prevent it from functioning. In this case, the antioxidant additive will inhibit oxidation of the coating, making it more durable in this case.

The additive mixtures described herein may be selected based on the determined defects in the coating properties. The additive mixture is then formulated to address these deficiencies. For example, if copper is identified as the catalyst that initiates radical decomposition of the gel coat, the additive mixture will consist of an antioxidant that will migrate to the coating/copper interface to inhibit catalyzed passivating agents and inhibit any generated radicals.

The addition of these additives will also result in maintaining the gel nature of the coating, which will prevent problems with the flow, liquefaction, cracking, chipping and other macro-scale removal modes of the coating when exposed to extreme environments.

In one embodiment, the additive includes at least one corrosion inhibitor, such as a carboxylic acid. One non-limiting example of a carboxylic acid useful in the present disclosure is Irgacor 843 sold by BASF ^TM 。

In one embodiment, the additive includes at least one passivating agent, such as a hydrazide, triazole, or mixture thereof. Non-limiting embodiments of hydrazides useful in the present disclosure include dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ] (CAS No. 63245-38-5) or 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -N' - [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl ] propionyl hydrazide (CAS No. 32687-78-8).

Non-limiting embodiments of triazoles useful in the present disclosure include 3-salicylamide-1, 2, 4-triazole (CAS No. 36411-52-6), N-bis (2-ethylhexyl) -1H-methylbenzotriazole-1-methylamine (CAS No. 94270-86-7), or (platinate (2-), diamino chloride (N- (N-L- Γ -glutamyl-L-cysteinyl) glycinate (3-) -S) -, dihydro, (SP-4-2) -) (CAS No. 91273-04-0).

In one embodiment, the additive includes at least one primary antioxidant, such as an amine or a phenol. Non-limiting embodiments of amine primary antioxidants useful in the present disclosure include the reaction product of N-phenylaniline with 2, 4-trimethylpentene (CAS No. 68411-46-1), N-phenyl-1, 3-tetramethylbutylnaphthalen-1-amine (CAS No. 68259-36-9), or 4,4' -dioctyldiphenylamine (CAS No. 101-67-7).

Non-limiting embodiments of phenolic primary antioxidants useful in the present disclosure include n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (CAS No. 2082-79-3), pentaerythritol tetrakis (3, 5-di-tert-butyl-4-hydroxy) phenylpropionate (CAS No. 6683-19-8), the following isomeric reaction mixtures: isooctyl 3, 5-di-tert-butyl-4-hydroxyphenylpropionate (CAS number 125643-61-0), 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (CAS number 27676-62-6) or bis [3- [ 3-tert-butyl-4-hydroxy-5-tolyl ] propanoic acid ]2,4,8, 10-tetraoxaspiro [5.5] undecane-3, 9-diylbis (2-methylpropan-2, 1-diyl) ester (CAS number 90498-90-1).

In one embodiment, the additive includes at least one secondary antioxidant, such as a phosphite or thioether. Non-limiting embodiments of phosphite secondary antioxidants useful in the present disclosure include phenyl tris (2, 4-di-tert-butyl) phosphite (CAS No. 31570-04-4), 4' -butylidenebis- (3-methyl-6-tert-butylphenyl) -tetra (tridecyl) diphosphite (CAS No. 13003-12-8) and (12H-dibenzo [ D, G ] [1,3,2] dioxaphosphoric acid, 2,4,8, 10-tetra (1, 1-dimethylethyl) -6- [ (2-ethylhexyl) oxy ] -) (CAS No. 126050-54-2).

Non-limiting embodiments of thioether secondary antioxidants useful in the present disclosure include pentaerythritol tetrakis (3-laurylthiopropionate) (CAS No. 29598-76-3) and ditridecyl 3, 3-thiodipropionate (CAS No. 10595-72-9).

In one embodiment, the compositions disclosed herein comprise a tackifier. Non-limiting examples of tackifiers useful herein include low molecular weight hydrogenated hydrocarbon resins, partially hydrogenated colorless hydrocarbon resins, colorless cycloaliphatic hydrocarbon resins, aromatic modified cycloaliphatic hydrocarbon resins, and combinations thereof.

In one embodiment, the compositions disclosed herein comprise a plasticizer. Non-limiting examples of plasticizers useful herein include hydrogenated cycloaliphatic hydrocarbon resins, trimellitates, epoxidized vegetable oils, high molecular weight phthalates, cycloparaffin plasticizers, and silicone oils.

In one embodiment, the additive may include one or more acid scavengers. Non-limiting examples of acid scavengers that may be widely used herein include stearates, carbonates, hydroxides, and hydrotalcites. For example, acid scavengers include calcium stearate, zinc calcium stearate or epoxidized octyl stearate, zinc carbonate, magnesium and aluminum hydroxide carbonates, magnesium hydroxide and synthetic hydrotalcite including magnesium/aluminum-hydrotalcite.

In one embodiment, the composition includes a UV dye. Non-limiting examples of UV dyes that can be used are 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiophene, 2' - (4, 4' -distyryl-) bisbenzoxazole, solvent yellow 43, carbon black, pigment yellow 101, N ' -bis (2, 6-diisopropylphenyl) -3,4,9, 10-perylene tetracarboxylic diimide, other perylene dyes and anthracene dyes.

The compositions disclosed herein provide a number of benefits over existing conventional compositions. Non-limiting examples of such benefits include:

the inertness and durability of the more environmentally friendly material is increased.

The coating formulation is designed to respond to the substrate, wherein one of the additives migrates from the bulk of the coating to the problematic substrate to strengthen the interface between the coating and the substrate.

The coating formulation is designed to respond to the environment in which one of the additives migrates to the coating/air interface to enhance its performance.

The coating formulation is designed to respond to a stimulus such as heat or magnetism, which is used to manipulate one of the additives to initiate a reaction or migration (e.g., to the interface) within the coating.

The coating formulation is designed to respond to the absorption of the foreign component, wherein the additive responds, targets or deactivates any foreign material from harsh environments such as moisture, hazardous gases such as sulfur oxides or unwanted particles such as metal particles/shavings.

The coating is designed to have discrete rheological properties in cross section.

The foregoing benefits may be used to protect the electronic device from conductive materials of the external environment, such as water or body fluids, dust or other particulates, and the like. Figures 2-7 provide illustrations of compositions for preparing novel gel state coatings, methods of treating substrates with gel state coatings, and substrates comprising gel state coatings.

Referring to fig. 2, the schematic diagram shown herein illustrates an apparatus for measuring insulation resistance on a printed circuit board as described herein. Specifically, fig. 2 shows how insulation properties were measured on various circuits on coated industry standard IPC-B-25A boards when immersed in tap water at 20V for 30 minutes.

The mechanism by which the additives disclosed herein result in improved performance is illustrated in fig. 5 and 6, which demonstrate migration of the additives from the coating to the interface at the substrate surface (fig. 3) or air surface (fig. 4). For example, fig. 3 illustrates migration of additives from a coating to a coating/substrate interface. This embodiment may be used to apply a passivation layer on a substrate. Fig. 4 shows a second schematic illustrating migration of additives from the coating to the coating/air interface. This embodiment may be used to increase the mechanical properties of the coating itself.

The above mechanism may be specifically selected by varying the manner in which the composition including the various additives is applied to the substrate. For example, as shown in fig. 5, the stepwise application of various additives indicates that the substrate is coated by first applying a passivating agent (in step 1) before applying the composition with one or more additional additives (in step 2). Finally, step 3 of fig. 5 shows the application of an insulating (e.g., resistant to molecular diffusion, increasing resistance, etc.) layer on top of the composition.

Once the desired coating is applied to the substrate via any of the methods described herein, including the stepwise method of fig. 5, a gel coat is formed.

In certain embodiments, the coatings described herein can be formulated to allow the additive to migrate out of the coating according to the desired effect. For example, FIG. 6 shows a schematic diagram indicating migration of additives from the external environment to a particular material, which migration may affect coating properties such as rust or metal particles. In addition to the metal particles, materials from the environment that may affect the performance of the coating may include moisture, dust, flux residue, any fluid that may be seen once the coating is assembled into the device, such as antifreeze, windshield wiper fluid, brake oil, and the like.

In another embodiment, the coatings described herein can be formulated to allow the migration of additives to the surface of the coating to provide an insulating layer on top of the coating. For example, fig. 7 shows a sixth schematic diagram that demonstrates the migration of additives from the coating to the coating/air interface to enhance performance at the air-coating interface.

Various mechanisms allow one to modify the additives to achieve the desired properties that allow the disclosed durable coatings to be used in a variety of applications, such as automotive electronic coatings that can withstand high temperatures and harsh environments that would otherwise cause hydrolytic, thermal, or oxidative decomposition. In general, the present disclosure provides gel state coatings that exhibit improved durability properties, thereby providing uses where it was previously not possible to use gel state coatings.

In some embodiments, the coating may have electrical insulation properties. As used herein, a coating having electrical insulating properties is defined as a coating through which no or very little current flows under the influence of an electric field. Generally, an electrical insulator is a material that has little to no electrical conductivity, thus allowing little to no current to flow through it.

In various embodiments, a portion or all of the internal components of the electronic device may be coated with the gel state coating without masking any portion of the electronic device prior to introducing additional components into the device. The component may be introduced after the coating is applied and the coating does not inhibit the flow of current between the component and the electronic device. Manufacturing costs and difficulty are often increased by masking. The use of gel coats as disclosed herein may result in reduced manufacturing costs and difficulty due to the need for masking having been greatly reduced or completely eliminated.

The viscoplastic properties of the film formers described herein allow the gel state coating to flow in certain situations. This allows for easy reworking of the coated printed circuit board assembly. For conventional conforma and vacuum coatings that do not exhibit flow or deformation, it is difficult to rework the coating into solder or repair existing components.

In some embodiments, the solvated coating may be spread on a substrate as described by a spreading coefficient (S), which is shown in the following equation:

S＝γ _SA -(γ _SC +γ _CA )

in the above equation, γ _SA Representing the surface energy between the substrate and air, gamma _SC Represents the surface energy between the substrate and the coating, and γ _CA Indicating the surface energy between the coating and the air. When the spreading coefficient is positive or gamma _SA Greater than (gamma) _SC +γ _CA ) When spreading may occur. When the spreading factor is positive, this means that wetting of the coating on the substrate will be completed. On the other hand, when the spreading factor is not positive, only partial or incomplete wetting is achieved. Instead, spreading the liquid may form a pellet or a floating lens.

In one embodiment, the thickness of the dried or unsolvated gel-state coating may be from 1 μm to 500 μm, such as from 5 μm to 100 μm, such as from 10 μm to 50 μm, when applied as a coating. The coating thickness can be measured by non-destructive optical techniques such as ellipsometry, spectroscopic reflection techniques such as interferometry, and confocal microscopy. Non-limiting examples of lossy methods of measuring coating thickness include SEM. Conventional coatings (such as conforma and vacuum coatings) are typically much thicker. For example, conventional coatings typically range in thickness up to hundreds of microns, which can block radio frequency and Wi-Fi transmission of electronic devices, and also act as thermal insulators. The thinner extent of the gel-state coating does not adversely affect the function of the electronic device nor does the gel-state coating act as a thermal insulator. A non-limiting example of a functional electronic device is a fully assembled printed circuit board. Fully assembled printed circuit boards with gel state coatings will exhibit normal radio frequency performance, normal thermal performance and other normal functionality.

In one embodiment, the at least one film former may comprise a hydrophobic material, such as a material comprising a polyolefin, polyacrylate, polyurethane, epoxy, polyamide, polyimide, polysiloxane.

In one embodiment, the disclosed compositions may also include additives that improve the manufacture of the composition, such as surfactants, dispersants, and the like. The composition may also include additives that alter and improve the rheological properties of the chemical formulation. Examples of surfactants may include ionic and nonionic industrial surfactants such as Triton-X, capstone and the like, and molecules such as fatty acid alcohols, esters, acids or amides that exhibit surface-active properties. Examples of dispersants and rheology modifiers may include electrostatically stable molecules such as long chain polyacrylic acid, sterically stable highly branched polymer molecules, nanoparticles that increase bulk viscosity, or submicron-sized particles of metal oxides. Other materials exhibiting elasto-viscoplastic properties may be used as the gel state coating.

In some embodiments, the compositions described herein may also be suspended or dissolved in a suitable carrier solvent. Non-limiting examples of suitable carrier solvents may be low molecular weight mineral oils, paraffinic or isoparaffins, low molecular weight linear or cyclic silicones, alkyl acetates, ketones, fully or partially halogenated hydrocarbons (including but not limited to paraffinic, alkene, alkyne, aromatic compounds, etc.), or aldehydes. In one embodiment, the carrier solvent comprises methylcyclohexane.

The gel state coatings described herein may be designed to prevent different types of liquids. The gel state coating may exhibit hydrophobic, hydrophilic, oleophobic, or oleophilic properties or any combination thereof. In one embodiment, the gel state coating contains a hydrophobic material, such as a polysiloxane.

In some embodiments, the gel state coating may have an aesthetic change. The refractive index of the coating may be designed using techniques known in the art. In one embodiment, the gel state coating may be designed to match the refractive index of the transparent material. Matching the refractive index of the transparent material can maintain the clarity and transparency of the final product. In other embodiments, the refractive index of the gel state coating may be designed to match the refractive index of other desired materials.

In one embodiment, a method of protecting an electronic device from contamination by a liquid is described. In this embodiment, the protection of the electronic device may be achieved by treating the electronic device with a gel state coating as described above.

Many different methods can be used to form the coating. Non-limiting examples of methods that can be used to form the disclosed coatings include physical processes such as printing, spraying, dipping, rolling, brushing, spraying, knife coating, or needle dispensing. Other techniques may also be used to form the moisture barrier coating.

As previously mentioned, the properties of the gel state coating allow processing of the electronic device without the need to mask the components prior to processing. Accordingly, the disclosed method includes processing an electronic device with masked or unmasked components. The component may be introduced after application without impeding the current flow between the electronic device and the component.

In one embodiment, a portion or all of the internal components of the electronic device may be coated with a gel state coating in a single application. In another embodiment, the gel state coating may be applied as a coating to only certain portions of the electronic device. Furthermore, in another embodiment, the gel coat may be applied to electronic devices in a variety of applications.

Conventional conforma and vacuum coatings have limited methods of application. Some application methods are not available due to the need to mask many components on the electronic device. A greater variety of application methods can be used to apply the coating. Some application methods may allow thinner gel-state coatings to be applied to electronic devices. Non-limiting examples of how the gel-state coating may be applied to the electronic device include atomized or non-atomized spray coating, dip coating, film coating, spray, or needle dispensing. Other methods of applying the gel state coating may also be used, such as by vapor deposition. Non-limiting examples of such vapor deposition techniques include Chemical Vapor Deposition (CVD), plasma-based coating processes, atomic Layer Deposition (ALD), physical Vapor Deposition (PVD), vacuum deposition processes, sputtering, and the like.

In one embodiment, the use of any of the disclosed methods of applying a gel state coating to an electronic device will produce a gel state coating on the electronic device having a thickness of 1-100 μm. The coating thickness does not inhibit the functionality or thermal performance of the electronic device. In addition, the adhesive properties of the gel-state coating may allow the coating to deform or flow when the components are introduced.

As described above, non-limiting embodiments of the electronic device may apply the gel state coating to the printed circuit board. The use of conventional conforma and vacuum coatings for printed circuit boards is expensive because many components need to be masked and a limited number of application methods can be used. For example, dip coating is difficult to apply as a conformal coating, because the coating penetrates everywhere, so masking must be perfect. In this embodiment, the printed circuit board may be coated with the gel state coating using a dip coating method because masking is not required. Any connector, such as a substrate female connector that connects a male connector to a printed circuit board, may be connected after application without affecting the current. The gel-state coating flows or deforms under the applied force to allow the formation of a bond.

Exemplary deposition methods

In one embodiment, a syringe and needle may be used to dispense the disclosed compositions. For example, the syringe may be fitted with a needle having a gauge size of 10-32, such as a gauge size of 16, 18 or 20, which will vary depending on the desired application.

In another embodiment, the disclosed compositions can be dispensed using a manual spray device. For example, a hand-held spray gun may be used to atomize the coating, such as by using compressed air or nitrogen.

In another embodiment, the disclosed compositions can be dispensed using an automated dispensing mechanism that can be used to apply a coating to an electronic device. For example, various nozzles that can be used to apply the coatings described herein to dispensing, such as Nordson Asymtek ^TM A wide-beam spray valve. In other embodiments, the nozzle may comprise a spray valve, including a PVA film application valve, or a valve used in PVA6 automated coating dispensing machines.

Measurement technique

After the coating is applied to the electronic device, various properties can be measured in the following manner.

The hydrophobicity or hydrophilicity of a coating can be measured by observing the contact angle formed by a droplet on the surface of the coating. The oleophobicity or lipophilicity of a coating can be measured by observing the contact angle that a hexadecane droplet forms on the surface of the coating.

The electrical insulation of the coating can also be determined by measuring the dielectric withstand voltage on the coated circuit board. A continuously increasing voltage may be applied to the coated circuit board and the voltage of the current arc through the air may be determined. This voltage is a measure of the effectiveness of the coating.

The electrical insulation of the coating can also be determined by measuring the material electrical properties of the coating, such as loss tangent or dielectric constant, using a network analyzer.

The non-newtonian, viscoelastic, viscoplastic and elasto-viscoplastic properties of the coating can be measured by observing various properties. The response of the coating to the applied stress or strain can be measured using a rheometer to study the deformation of the coating. The viscoelastic modulus can be measured using a small angle oscillation stress sweep, and the yield stress and high shear viscosity can be measured using a stress sweep. The degree of deformation can also be measured by quantifying hardness, modulus, viscosity, breaking strain, creep, and ductility in the tensile, compressive, and shear directions.

The features and advantages of the present invention are more fully shown by the following examples, which are provided for illustrative purposes and should not be construed as limiting the invention in any way.

Examples

The following examples disclose methods of preparing gel state coatings according to the present disclosure. Non-newtonian, viscoelastic, viscoplastic and/or elasto-viscoplastic compositions for use as coatings for electronic devices. After preparation, the composition may be applied to an electronic device using known techniques to form a protective coating.

Example 1

The following examples provide methods of preparing silicone-free gel-state coatings having improved properties according to the present disclosure.

A composition was prepared comprising the following ingredients: 8.99 wt.% styrenic block copolymer and 8.99 wt.% poly alpha olefin electrical insulator/film former/rheology modifier; a passivating agent comprising 0.18 wt.% dodecanedioic acid, 1, 12-bis [2- (2-hydroxybenzoyl) hydrazide ]; a primary antioxidant comprising 0.05 wt.% n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate; a second antioxidant comprising 0.09 weight percent of ditridecyl 3, 3-thiodipropionate; and a UV dye comprising 0.02 wt.% of 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiophene.

These ingredients were added to a glass beaker and mixed in a carrier solvent comprising 81.74 wt% methylcyclohexane. Mix for 8 hours at room temperature using a magnetic stirrer.

Example 2

A composition substantially similar to example 1 but without UV dye was prepared. The composition comprises the following components: an electrical insulator/film former/rheology modifier comprising 8.99 wt% styrenic block copolymer and 8.99 wt% polyalphaolefin; a passivating agent comprising 0.18 wt.% dodecanedioic acid, 1, 12-bis [2- (2-hydroxybenzoyl) hydrazide ]; a primary antioxidant comprising 0.05 wt.% n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate; and a second antioxidant comprising 0.09 weight percent of ditridecyl 3, 3-thiodipropionate.

Comparative example 1

The comparative composition is similar to examples 1 and 2 but without additives including passivating agents, antioxidants and dyes. The composition comprises the following components: an electrical insulator/film former/rheology modifier comprising 8.99 wt% styrenic block copolymer and 8.99 wt% polyalphaolefin mixed in a carrier solvent comprising 82 wt% methylcyclohexane.

All ingredients were added to a glass beaker and stirred at room temperature for 8 hours using a magnetic stirrer.

Example 3

This example is based on a formulation with styrene- [ ethylene- (ethylene-propylene) ] -styrene (SEEPS) block copolymer with additives. The composition comprises 4% by weight of SEEPS polymer, white mineral oil (8%), a passivating agent comprising 0.08% by weight of 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -N' - [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl ] propionyl hydrazide, 0.08% by weight of a primary phenolic antioxidant comprising the following isomers of reaction mass: isooctyl 3, 5-di-tert-butyl-4-hydroxy-phenylpropionate and 0.12 wt% of a thioether antioxidant comprising ditridecyl 3, 3-thiodipropionate were mixed in a carrier solvent comprising 87.7 wt% methylcyclohexane.

Comparative example 2

The comparative composition is similar to example 3 but contains no additives including passivating agents, antioxidants and dyes. The composition comprises the following components: 4% by weight of styrene- [ ethylene- (ethylene-propylene) ] -styrene (SEEPS) and 8% by weight of white mineral oil were mixed in a carrier solvent comprising 88% by weight of methylcyclohexane.

Example 4

This example is based on a formulation with a styrene- [ ethylene- (ethylene-propylene) ] -styrene (SEEPS) block copolymer with end block stabilizers and other additives.

The composition comprises 4 wt% of a styrenic block copolymer and 7 wt% of a polyalphaolefin; 1.1% by weight of Eastman sold under the name EndexComprises mixing 0.11 wt% of passivating agent 3-salicylamide-1, 2, 4-triazole, 0.11 wt% of phenolic antioxidant 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-stearyl alcohol ester, 0.06 wt% of thioether antioxidant 3, 3-thiodipropionic acid ditridecyl ester in a carrier solvent comprising 87.62 wt% of methylcyclohexane.

The hydrocarbon resin endblock stabilizer was added to methylcyclohexane in a beaker and stirred at 80 deg.c until dissolved. All other ingredients were further added and stirred at room temperature for 8 hours.

Comparative example 3

The comparative composition is similar to example 4 but contains no additives including passivating agents, antioxidants and dyes. The composition comprises the following components: the composition comprises 4 wt% styrene block copolymer and 7 wt% poly alpha olefin mixed in 89 wt% methylcyclohexane.

Example 5

This example is based on a formulation with 3.55 wt% styrene-ethylene/butylene-styrene (SEBS); 0.89 wt% styrene-ethylene/propylene-styrene (SEPS) block copolymer; 3.55 wt% of a polyalphaolefin; a passivating agent comprising 0.18 wt.% of dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ]; a phenolic antioxidant comprising 0.045 wt.% n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (0.045%); a thioether antioxidant comprising 0.09% ditridecyl 3, 3-thiodipropionate, mixed in 81.74% by weight methylcyclohexane.

Example 6

This example is based on a formulation with 3.55 wt% styrene-ethylene/butylene-styrene (SEBS); 0.53 wt% styrene-ethylene/propylene-styrene (SEPS); and maleic anhydride-treated SEBS block copolymer-SEBS (3.55%), SEPS (0.53%), maleic anhydride-treated SEBS (0.36%); 3.55 wt% of a polyalphaolefin; a passivating agent comprising 0.08 wt.% of dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ]; a phenolic antioxidant comprising 0.02 wt.% n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (0.045%); a thioether antioxidant comprising 0.04% ditridecyl 3, 3-thiodipropionate, mixed in a solvent comprising 81.74% by weight methylcyclohexane.

Example 7

This example is based on a formulation with polyisobutylene and SEEPS copolymer. In particular, 10% by weight of polyisobutene (10%), 10% by weight of SEEPS polymer; 0.1 wt% of a passivating agent comprising 3-salicylamide-1, 2, 4-triazole; 0.2 wt% of a phenolic antioxidant comprising the following isomeric reaction mass: 3, 5-di-tert-butyl-4-hydroxyphenylpropionic acid isooctyl ester; 0.1 wt.% of a thioether antioxidant comprising ditridecyl 3, 3-thiodipropionate, mixed in a solvent comprising 79.60 wt.% of isoparaffin.

Example 8

This example is based on a formulation with a polyethylene/polypropylene (PE/PP) copolymer and silicone oil. The composition comprises 3 wt.% of a PE/PP copolymer; 10 wt% methyl terminated PDMS (30,000 cst), 0.13 wt% passivating agent comprising dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ]; 0.04 wt.% of a phenolic antioxidant comprising n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate; and 0.04 wt% of ditridecyl 3, 3-thiodipropionate in a solvent comprising 86.80 wt% methylcyclohexane.

Example 9

This example is based on a formulation with lithium stearate and alumina. In particular, the composition comprises 2.8 wt% lithium stearate, 1.1 wt% organosilane treated hydrophobic alumina; 9.4 wt% of a polyalphaolefin; a passivating agent comprising 0.13% of dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ]; a phenolic antioxidant comprising 0.03% n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate; a thioether antioxidant comprising 0.07% ditridecyl 3, 3-thiodipropionate; UV dye comprising 0.01% by weight of 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiophene, azeotropic fluoroether solvent mixture (86.49%).

The lithium stearate, polyalphaolefin and azeotropic fluoroether solvent mixture was added to the beaker and stirred at 60 ℃ until the lithium stearate was completely dissolved.

The mixture was cooled to room temperature, organosilane treated hydrophobic alumina was added and mixed using a high shear homogenizer. The remaining ingredients were added and mixed until dissolved.

Example 10

The following examples provide methods of preparing polyacrylate coatings having improved performance properties according to the present disclosure.

A20 mL scintillation vial with a cap septum was charged with a stir bar, 0.500g butyl acrylate, 2.500g methyl methacrylate, 0.060g azobisisobutyronitrile, and 1.500g n-butyl acetate. After sealing the vial, the solution was gently purged with nitrogen through the cap septum using a hypodermic needle while stirring for 30 minutes. After purging, the inlet and outlet needles were removed and the vials were transferred to an aluminum heating block and heated at 85 ℃ for 5 hours with stirring. To quench the reaction, the vials were removed from the heating block, opened to air, and cooled with an ice bath.

Example 11

To a 20mL scintillation vial with a cap septum was added a stir bar, 2.000g of 2-ethylhexyl acrylate, 1.700g of isobornyl methacrylate, 0.074g of azobisisobutyronitrile, and 0.200g of n-butyl acetate. After sealing the vial, the solution was gently purged with nitrogen through the cap septum using a hypodermic needle while stirring for 30 minutes. After purging, the inlet and outlet needles were removed and the vials were transferred to an aluminum heating block and heated at 85 ℃ for 5 hours with stirring. To quench the reaction, the vials were removed from the heating block, opened to air, and cooled with an ice bath.

The reaction mixture was diluted to 10.7 wt% with n-butyl acetate and mixed for 30 minutes at room temperature using a magnetic stirrer.

Industrial applicability

The disclosed composition for forming a conformal gel coating, a conformal coating for a device or substrate, and a method of applying a device or substrate with the conformal coating may be used to protect a device or substrate from various environments by acting as a protective layer.

In one embodiment, the surface may comprise metal and the undesirable environment is corrosive and aqueous, such as condensation water, tap water, sweat, sebum, brine, carbonated beverages, coffee, liquid coolant, or antifreeze. In one embodiment, the surface comprises a metal that exhibits galvanic corrosion, and the unnecessary environment causes galvanic corrosion. More generally, the surface may comprise any metal that can oxidize, and the unwanted environment causes oxidation to be selected from air, oxygen, or water vapor.

In another embodiment, the surface comprises active electronics in a printed circuit board, and the unwanted environment comprises a corrosive gas selected from chlorine, water vapor, hydrogen sulfide, hydrogen chloride, or oxides of nitrogen and sulfur. In yet another embodiment, the surface comprises active electronics in a printed circuit board, and the unwanted environment comprises a conductive liquid selected from water, sweat, and other corrosive fluids.

Conformal gel coatings constructed in accordance with the principles of the present disclosure generally exhibit improved functional durability while retaining deformability due to the combination of at least one film former; and at least one additive.

For example, the at least one film former may include a polyolefin, polyacrylate, polyurethane, epoxy, polyamide, polyimide, polysiloxane, or a combination thereof.

The one or more additives may be selected from: an antioxidant; a passivating agent; UV absorbers or stabilizers; a rheology modifier; an adhesion promoter; a wetting agent; a tackifier; a plasticizer; a dispersing agent; leveling agent; a defoaming agent; processing an additive; or a combination thereof.

The antioxidant may include a phenolic antioxidant, an amine antioxidant, a thioether antioxidant, a phosphite antioxidant, or a combination thereof.

The phenolic antioxidants may be selected from n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (CAS number 2082-79-3), pentaerythritol tetrakis (3, 5-di-tert-butyl-4-hydroxy) phenylpropionate (CAS number 6683-19-8), the following isomeric reaction mixtures: isooctyl 3, 5-di-tert-butyl-4-hydroxyphenylpropionate (CAS number 125643-61-0), 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid (CAS number 27676-62-6) or bis [3- [ 3-tert-butyl-4-hydroxy-5-tolyl ] propionic acid ]2,4,8, 10-tetraoxaspiro [5.5] undecane-3, 9-diylbis (2-methylpropan-2, 1-diyl) ester (CAS number 90498-90-1) and combinations thereof.

The amine antioxidant may be selected from the group consisting of the reaction product of N-phenylaniline with 2, 4-trimethylpentene (CAS No. 68411-46-1), N-phenyl-1, 3-tetramethylbutylnaphthalen-1-amine (CAS No. 68259-36-9), 4' -dioctyldiphenylamine (CAS No. 101-67-7), other alkylated amines, and combinations thereof.

The thioether antioxidant may be selected from pentaerythritol tetrakis (3-laurylthiopropionate) (CAS# 29598-76-3) or ditridecyl 3, 3-thiodipropionate (CAS# 10595-72-9) and combinations thereof.

Phosphite antioxidants may be selected from phenyl tris (2, 4-di-tert-butyl) phosphite (CAS No. 31570-04-4), phenyl 4,4' -butylidenebis- (3-methyl-6-tert-butylphenyl) -tetra (tridecyl) diphosphite (CAS No. 13003-12-8), (12H-dibenzo [ D, G ] [1,3,2] dioxaphosphoric acid, 2,4,8, 10-tetrakis (1, 1-dimethylethyl) -6- [ (2-ethylhexyl) oxy ] -) (CAS No. 126050-54-2) or phenyl tris (2, 4-di-tert-butyl) phosphite (CAS No. 31570-04-4) and combinations thereof.

The passivating agent may include an acyl or triazole selected from the group consisting of dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ] (CAS No. 63245-38-5), 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -N' - [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl ] propionyl hydrazide (CAS No. 32687-78-8), 1,2, 4-triazole (CAS No. 288-88-0), 3-salicylamide-1, 2, 4-triazole (CAS No. 36411-52-6), N-bis (2-ethylhexyl) -1H-methylbenzotriazole-1-methylamine (CAS No. 94270-86-7), platinate (2-), diamino chloride (N-L- γ -glutamyl-L-cysteinyl) glycinate (3-) -S) -, dihydro, (CAS No. 91273-04), and combinations thereof.

UV absorbers or stabilizers may include carbon black, rutile titanium oxide, hindered amines, benzophenones, and combinations thereof.

Rheology modifiers may include sodium polyacrylate, polyamide wax, polyethylene wax, hydrogenated castor oil, attapulgite clay, fumed silica, precipitated silica, metal oxide particles, and combinations thereof.

Adhesion promoters may include chlorinated polyolefins, cyanoacrylate primers, polyester alkyl ammonium salts, amino-functional polyethers, maleic anhydride, carboxylated polypropylene, glycidyl methacrylate-functional polyolefins, trimethoxyvinylsilane, silanes, and combinations thereof.

Wetting or dispersing agents may include alkylammonium salts of polycarboxylic acids, alkylammonium salts of acidic polymers, salts of unsaturated polyamine amides and acidic polyesters, maleic anhydride functionalized ethylene butyl acrylate copolymers, other ionic or nonionic surfactants, and combinations thereof.

The tackifier may comprise a hydrogenated hydrocarbon resin or a cycloaliphatic hydrocarbon resin.

Plasticizers may include hydrogenated cycloaliphatic hydrocarbon resins, trimellitates, high molecular weight phthalates, silicone oils, octyl epoxy esters, or hydrogenated light naphthenic petroleum distillates.

The leveling agent may include a silicone, a liquid polyacrylate, an ionic surfactant, a nonionic surfactant, or a mixture thereof.

The disclosed compositions may be formulated in one or more solvents such as aromatic solvents selected from toluene, xylene and naphtha, alkanes selected from isoparaffinic solvents, hexane, methylcyclohexane, alkenes, alcohols selected from butanol, alkyl acetate selected from t-butyl acetate, alkyl ethers, ketones selected from methyl ethyl ketone, aldehydes, and fully or partially halogenated hydrocarbons.

The composition may further comprise at least one pigment or UV dye selected from the group consisting of 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiophene (CAS No. 7128-64-5), 2' - (4, 4' -distyryl-) bisbenzoxazole (CAS No. 1533-45-5), solvent yellow 43 (CAS No. 19125-99-6), carbon black (CAS No. 1333-86-4), pigment yellow 101 (CAS No. 2387-03-3), N ' -bis (2, 6-diisopropylphenyl) -3,4,9, 10-perylene tetracarboxylic diimine (CAS No. 82953-57-9), other perylene dyes, and anthracene dyes.

The composition exhibits viscoelastic, viscoplastic or elastohydroplastic flow properties when formulated in a solvent or once the solvent evaporates after application. It may also be siloxane-free, non-halogenated or both.

The composition may have a volatile organic content of 650g/L or less.

The composition has a thickness of 25nm to 500 μm when applied on various surfaces.

In one embodiment, the compositions exhibit electrical insulating properties such that when the compositions are placed between two metal contacts, they prevent current leakage or arcing between the two metal contacts. The electrical insulation properties may also prevent current from flowing from the active electronic devices on the printed circuit board to the conductive medium or environment, or electrostatic discharge from the charge carriers to the active electronic devices on the printed circuit board.

As described above, the additives described herein provide compositions having enhanced durability to oxidative degradation as compared to compositions without the additives. For example, the additive provides the composition with enhanced mechanical stability compared to the composition without the additive and does not undergo liquefaction, hardening, or other phase changes. In one embodiment, the one or more additives preferentially migrate to the coating/substrate interface to isolate the substrate from the remainder of the coating. For example, when the composition is formulated into a gel coat as described herein, the additive may be a passivating agent that migrates and adsorbs onto the coating/substrate interface to inhibit catalytic activity from the substrate. The one or more additives preferentially migrate to areas of the substrate where there is no coating to protect the substrate from the environment.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the invention being indicated by the following claims.

Claims

1. A composition for forming a conformal gel coating to protect a substrate from various environments, the composition comprising:

at least one film forming agent;

at least one additive; and

optionally at least one of the solvents is used,

wherein the composition is deformable, flowable, electrically insulating, and free of fluorine when applied as a coating.

2. The composition of claim 1, wherein the at least one film former comprises a polyolefin, polyacrylate, polyurethane, epoxy, polyamide, polyimide, polysiloxane, or a combination thereof.

3. The composition of claim 1, wherein the one or more additives are selected from the group consisting of:

an antioxidant;

a passivating agent;

UV absorbers or stabilizers;

a rheology modifier;

an adhesion promoter;

a wetting agent;

a tackifier;

a plasticizer;

a dispersing agent;

leveling agent;

a defoaming agent;

processing an additive; or (b)

A combination thereof.

4. The composition of claim 3, wherein the antioxidant comprises a phenolic antioxidant, an amine antioxidant, a thioether antioxidant, a phosphite antioxidant, or a combination thereof.

5. The composition of claim 4, wherein the phenolic antioxidant is selected from n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (CAS No. 2082-79-3), pentaerythritol tetrakis (3, 5-di-tert-butyl-4-hydroxy) phenylpropionate (CAS No. 6683-19-8), a reaction mass of the following isomers: isooctyl 3, 5-di-tert-butyl-4-hydroxyphenylpropionate (CAS number 125643-61-0), 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid (CAS number 27676-62-6) or bis [3- [ 3-tert-butyl-4-hydroxy-5-tolyl ] propionic acid ]2,4,8, 10-tetraoxaspiro [5.5] undecane-3, 9-diylbis (2-methylpropan-2, 1-diyl) ester (CAS number 90498-90-1) and combinations thereof.

6. The composition of claim 4, wherein the amine antioxidant is selected from the group consisting of the reaction product of N-phenylaniline with 2, 4-trimethylpentene (CAS No. 68411-46-1), N-phenyl-1, 3-tetramethylbutylnaphthalen-1-amine (CAS No. 68259-36-9), 4' -dioctyldiphenylamine (CAS No. 101-67-7), other alkylated amines, and combinations thereof.

7. The composition of claim 4, wherein the thioether antioxidant is selected from pentaerythritol tetrakis (3-laurylthiopropionate) (CAS No. 29598-76-3) or ditridecyl 3, 3-thiodipropionate (CAS No. 10595-72-9), and combinations thereof.

8. The composition of claim 4, wherein the phosphite antioxidant is selected from phenyl tris (2, 4-di-t-butyl) phosphite (CAS No. 31570-04-4), phenyl 4,4' -butylidenebis- (3-methyl-6-t-butylphenyl) -tetra (tridecyl) diphosphite (CAS No. 13003-12-8), (12H-dibenzo [ D, G ] [1,3,2] dioxaphosphoric acid, 2,4,8, 10-tetra (1, 1-dimethylethyl) -6- [ (2-ethylhexyl) oxy ] -) (CAS No. 126050-54-2), or phenyl tris (2, 4-di-t-butyl) phosphite (CAS No. 31570-04-4), and combinations thereof.

9. The composition of claim 4, wherein the passivating agent comprises a hydrazide selected from dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ] (CAS No. 63245-38-5), 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -N' - [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl ] propionyl hydrazide (CAS No. 32687-78-8), 1,2, 4-triazole (CAS No. 288-88-0), 3-salicylamide-1, 2, 4-triazole (CAS No. 36411-52-6), N-bis (2-ethylhexyl) -1H-methylbenzotriazole-1-methylamine (CAS No. 94270-86-7), platinate (2-), diamino chloride (N-L- γ -glutamyl-L-cysteinyl) glycinate (3-) -S) -, dihydro, (SP-4-2) - (273-04), and combinations thereof.

10. The composition of claim 3, wherein the UV absorber or stabilizer comprises carbon black, rutile titanium oxide, hindered amines, benzophenone, and combinations thereof.

11. The composition of claim 3, wherein the rheology modifier comprises sodium polyacrylate, polyamide wax, polyethylene wax, hydrogenated castor oil, attapulgite clay, fumed silica, precipitated silica, metal oxide particles, and combinations thereof.

12. The composition of claim 3, wherein the adhesion promoter comprises chlorinated polyolefin, cyanoacrylate primer, polyester alkyl ammonium salt, amino-functional polyether, maleic anhydride, carboxylated polypropylene, glycidyl methacrylate functional polyolefin, trimethoxyvinyl silane, and combinations thereof.

13. The composition of claim 3, wherein the wetting or dispersing agent comprises an alkylammonium salt of a polycarboxylic acid, an alkylammonium salt of an acidic polymer, salts of unsaturated polyamine amides and acidic polyesters, maleic anhydride functionalized ethylene butyl acrylate copolymers, other ionic or nonionic surfactants, and combinations thereof.

14. A composition according to claim 3, wherein the tackifier comprises a hydrogenated hydrocarbon resin or a cycloaliphatic hydrocarbon resin.

15. A composition according to claim 3, wherein the plasticizer comprises a hydrogenated cycloaliphatic hydrocarbon resin, trimellitate, high molecular weight phthalate, silicone oil, octyl epoxy or hydrogenated light naphthenic petroleum distillate.

16. The composition of claim 3, wherein the leveling agent comprises a silicone, a liquid polyacrylate, an ionic surfactant, a nonionic surfactant, or a mixture thereof.

17. The composition of claim 1, formulated in one or more solvents.

18. The composition of claim 17, wherein the one or more solvents comprise an aromatic solvent selected from toluene, xylene, and naphtha, an alkane selected from isoparaffinic solvents, hexane, methylcyclohexane, olefins, an alcohol selected from butanol, an alkyl acetate selected from t-butyl acetate, an alkyl ether, a ketone selected from methyl ethyl ketone, an aldehyde, and a fully or partially halogenated hydrocarbon.

19. The composition of claim 1, further comprising at least one pigment or UV dye selected from the group consisting of 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiophene (CAS No. 7128-64-5), 2' - (4, 4' -distyryl-) bisbenzoxazole (CAS No. 1533-45-5), solvent yellow 43 (CAS No. 19125-99-6), carbon black (CAS No. 1333-86-4), pigment yellow 101 (CAS No. 2387-03-3), N ' -bis (2, 6-diisopropylphenyl) -3,4,9, 10-perylene tetracarboxylic diimine (CAS No. 82953-57-9), other perylene dyes, and anthracene dyes.

20. The composition of claim 1, which exhibits viscoelastic, viscoplastic or elastohydroplastic flow properties when formulated in a solvent or once the solvent evaporates after application.

21. The composition of claim 1, which is silicone-free.

22. The composition of claim 1, which is non-halogenated.

23. The composition of claim 1, having a volatile organic content of 650g/L or less.

24. The composition of claim 1, having a thickness of 25nm to 500 μιη when applied on various surfaces.

25. The composition of claim 1, located between a surface and an unwanted environment and serving as a protective interface for the surface and the unwanted environment.

26. The composition of claim 25, wherein the surface comprises a metal and the unwanted environment is corrosive and aqueous.

27. The composition of claim 26, wherein the corrosive and aqueous environment is selected from condensed water, tap water, sweat, sebum, salt water, carbonated beverages, coffee, liquid coolant, or antifreeze.

28. The composition of claim 26, wherein the surface comprises a metal that exhibits galvanic corrosion, and the unwanted environment causes galvanic corrosion.

29. The composition of claim 26, wherein the surface comprises any metal that can oxidize and the unwanted environment causes oxidation to be selected from air, oxygen, or water vapor.

30. The composition of claim 26, wherein the surface comprises active electronics in a printed circuit board and the unwanted environment comprises a corrosive gas selected from chlorine, water vapor, hydrogen sulfide, hydrogen chloride, or nitrogen oxides and sulfur oxides.

31. The composition of claim 26, wherein the surface comprises active electronics in a printed circuit board and the unwanted environment comprises a conductive liquid selected from water, sweat, and other corrosive fluids.

32. The composition of claim 1, which exhibits electrical insulation properties.

33. The composition of claim 32, wherein the electrical insulation properties prevent current leakage or arcing between two metal contacts when the composition is placed between the two metal contacts.

34. The composition of claim 32, wherein the electrical insulation properties prevent current flow from active electronics on the printed circuit board to a conductive medium or environment.

35. The composition of claim 32, wherein the electrical insulation properties prevent electrostatic discharge from the charge carrier to active electronics on the printed circuit board.

36. The composition of claim 1, wherein the additive provides the composition with enhanced durability to oxidative degradation as compared to a composition without the additive.

37. The composition of claim 1, wherein the additive provides the composition with enhanced mechanical stability compared to a composition without the additive and does not undergo liquefaction, hardening, or other phase changes.

38. The composition of claim 1, wherein one or more of the additives preferentially migrate to the coating/substrate interface to isolate the substrate from the remainder of the coating.

39. The composition of claim 1, wherein the additive is a passivating agent that migrates and adsorbs onto the coating/substrate interface to inhibit catalytic activity from the substrate.

40. The composition of claim 1, wherein one or more of the additives preferentially migrate to areas of the substrate that are devoid of the coating to protect the substrate from environmental effects.

41. A conformal gel coating for protecting electronic components from various environments, said coating comprising:

at least one film forming agent; and

at least one additive

And optionally at least one solvent,

wherein the gel coat is deformable, flowable, electrically insulating, and fluorine-free.

42. The conformal gel coating of claim 41, wherein said at least one film former comprises a polyolefin, polyacrylate, polyurethane, epoxy, polyamide, polyimide, polysiloxane, fluoropolymer, or a combination thereof.

43. The conformal gel coating of claim 41, wherein said one or more additives are selected from the group consisting of:

an antioxidant;

a passivating agent;

UV absorbers or stabilizers;

a rheology modifier;

an adhesion promoter;

a wetting agent;

a tackifier;

a plasticizer;

a dispersing agent;

leveling agent;

a defoaming agent;

processing an additive; a kind of electronic device with high-pressure air-conditioning system

A combination thereof.

44. The conformal gel coating of claim 42, wherein said antioxidants comprise phenolic antioxidants, amine antioxidants, thioether antioxidants, phosphite antioxidants, and combinations thereof.

45. The conformal gel coating of claim 44, wherein said phenolic antioxidant is selected from the group consisting of n-stearyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (CAS No. 2082-79-3), pentaerythritol tetrakis (3, 5-di-tert-butyl-4-hydroxy) phenylpropionate (CAS No. 6683-19-8), and reaction products of the following isomers: isooctyl 3, 5-di-tert-butyl-4-hydroxyphenylpropionate (CAS number 125643-61-0), 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid (CAS number 27676-62-6) or bis [3- [ 3-tert-butyl-4-hydroxy-5-tolyl ] propionic acid ]2,4,8, 10-tetraoxaspiro [5.5] undecane-3, 9-diylbis (2-methylpropan-2, 1-diyl) ester (CAS number 90498-90-1) and combinations thereof.

46. The conformal gel coating of claim 44, wherein said amine antioxidant is selected from the group consisting of the reaction product of N-phenylaniline with 2, 4-trimethylpentene (CAS No. 68411-46-1), N-phenyl-1, 3-tetramethylbutylnaphthalen-1-amine (CAS No. 68259-36-9), 4' -dioctyldiphenylamine (CAS No. 101-67-7), other alkylated amines, and combinations thereof.

47. The conformal gel coating of claim 44, wherein said thioether antioxidant is selected from pentaerythritol tetrakis (3-laurylthiopropionate) (CAS No. 29598-76-3) or ditridecyl 3, 3-thiodipropionate (CAS No. 10595-72-9), and combinations thereof.

48. A conformal gel coating as claimed in claim 44, wherein said phosphite antioxidant is selected from phenyl tris (2, 4-di-tert-butyl) phosphite (CAS No. 31570-04-4), 4' -butylidenebis- (3-methyl-6-tert-butylphenyl) -tetra (tridecyl) diphosphite (CAS No. 13003-12-8), (12H-dibenzo [ D, G ] [1,3,2] dioxaphosphoric acid, 2,4,8, 10-tetra (1, 1-dimethylethyl) -6- [ (2-ethylhexyl) oxy ] -) (CAS No. 126050-54-2) or phenyl tris (2, 4-di-tert-butyl) phosphite (CAS No. 31570-04-4) and combinations thereof.

49. The conformal gel coating of claim 43, wherein said passivating agent comprises an acyl hydrazine selected from dodecanedioic acid bis [2- (2-hydroxybenzoyl) hydrazide ] (CAS No. 63245-38-5), 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -N' - [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl ] propionyl hydrazide (CAS No. 32687-78-8), 1,2, 4-triazole (CAS No. 288-88-0), 3-salicylamide-1, 2, 4-triazole (CAS No. 36411-52-6), N-bis (2-ethylhexyl) -1H-methylbenzotriazole-1-methylamine (CAS No. 94270-86-7), platinate (2-), diamino chloride (N-L- γ -acyl-L-cysteinyl) glycinate (3-) -) -, dihydro, (SP-4-2) - (273-04), and combinations thereof.

50. The conformal gel coating of claim 43, wherein said UV absorber or stabilizer comprises carbon black, rutile titanium oxide, hindered amines, benzophenones, and combinations thereof.

51. The conformal gel coating of claim 43, wherein said rheology modifier comprises sodium polyacrylate, polyamide wax, polyethylene wax, hydrogenated castor oil, attapulgite clay, fumed silica, precipitated silica, metal oxide particles, and combinations thereof.

52. The conformal gel coating of claim 43, wherein said adhesion promoter comprises chlorinated polyolefin, cyanoacrylate primer, polyester alkyl ammonium salt, amino-functional polyether, maleic anhydride, carboxylated polypropylene, glycidyl methacrylate functional polyolefin, trimethoxyvinyl silane, and combinations thereof.

53. The conformal gel coating of claim 43, wherein said wetting or dispersing agent comprises an alkylammonium salt of a polycarboxylic acid, an alkylammonium salt of an acidic polymer, salts of unsaturated polyamine amides and acidic polyesters, maleic anhydride functionalized ethylene butyl acrylate copolymer, other ionic or nonionic surfactants, and combinations thereof.

54. The conformal gel coating of claim 43, wherein said adhesion promoter comprises a hydrogenated hydrocarbon resin or a cycloaliphatic hydrocarbon resin.

55. The conformal gel coating of claim 43, wherein said plasticizer comprises a hydrogenated cycloaliphatic hydrocarbon resin, trimellitate, high molecular weight phthalate, silicone oil, octyl epoxy, or hydrogenated light naphthenic petroleum distillate.

56. The conformal gel coating of claim 43, wherein said planarizing agent comprises a silicone, a liquid polyacrylate, an ionic surfactant, a nonionic surfactant, or a mixture thereof.

57. The conformal gel coating of claim 42, wherein said conformal gel coating is formulated in one or more solvents.

58. The conformal gel coating of claim 57, wherein said one or more solvents comprises an aromatic solvent selected from toluene, xylene, and naphtha, an alkane selected from isoparaffinic solvents, hexane, methylcyclohexane, olefins, an alcohol selected from butanol, an alkyl acetate selected from t-butyl acetate, an alkyl ether, a ketone selected from methyl ethyl ketone, an aldehyde, and a fully or partially halogenated hydrocarbon.

59. The conformal gel coating of claim 41, further comprising at least one pigment or UV dye selected from the group consisting of 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiophene (CAS No. 7128-64-5), 2' - (4, 4' -distyryl-) bisbenzoxazole (CAS No. 1533-45-5), solvent yellow 43 (CAS No. 19125-99-6), carbon black (CAS No. 1333-86-4), pigment yellow 101 (CAS No. 2387-03-3), N ' -bis (2, 6-diisopropylphenyl) -3,4,9, 10-perylene tetracarboxylic diimine (CAS No. 82953-57-9), other perylene dyes, and anthracene dyes.

60. The conformal gel coating of claim 41, which exhibits viscoelastic, viscoplastic, or elastohydroplastic flow properties when formulated in a solvent or once the solvent evaporates after application.

61. The conformal gel coating of claim 41, which is silicone-free.

62. The conformal gel coating of claim 41, wherein said conformal gel coating is non-halogenated.

63. The conformal gel coating of claim 41, having a volatile organic content of 650g/L or less.

64. The conformal gel coating of claim 41, which when applied over a variety of surfaces, has a thickness of 25nm to 500 μm.

65. The conformal gel coating of claim 41, wherein said conformal gel coating is located between a surface and an unwanted environment and acts as a protective interface for said surface and said unwanted environment.

66. The conformal gel coating of claim 65, wherein said surface comprises a metal and said unnecessary environment is corrosive and aqueous.

67. The conformal gel coating of claim 66, wherein said corrosive and aqueous environment is selected from condensed water, tap water, sweat, sebum, salt water, carbonated beverages, coffee, liquid coolant, or anti-freeze.

68. The conformal gel coating of claim 65, wherein the surface comprises a metal that exhibits galvanic corrosion and the unnecessary environment causes galvanic corrosion.

69. The conformal gel coating of claim 65, wherein the surface comprises any metal that may oxidize and the unnecessary environment causes oxidation to be selected from air, oxygen, or water vapor.

70. The conformal gel coating of claim 65, wherein said surface comprises active electronics in a printed circuit board and said unnecessary environment comprises a corrosive gas selected from chlorine, water vapor, hydrogen sulfide, hydrogen chloride, or nitrogen oxides and sulfur oxides.

71. The conformal gel coating of claim 65, wherein said surface comprises active electronics in a printed circuit board and said unnecessary environment comprises a conductive liquid selected from the group consisting of water, sweat, and other corrosive fluids.

72. The conformal gel coating of claim 41, wherein said conformal gel coating exhibits electrical insulation properties.

73. The conformal gel coating of claim 72, wherein the electrical insulation properties prevent current leakage or arcing between two metal contacts when the composition is disposed between the two metal contacts.

74. The conformal gel coating of claim 72, wherein the electrical insulation properties prevent current flow from active electronics on the printed circuit board to a conductive medium or environment.

75. The conformal gel coating of claim 72, wherein the electrical insulation properties prevent electrostatic discharge from charge carriers to active electronics on the printed circuit board.

76. The conformal gel coating of claim 41, wherein said additive provides said composition with enhanced durability to oxidative degradation as compared to a composition without said additive.

77. The conformal gel coating of claim 41, wherein said additive provides said composition with enhanced mechanical stability compared to a composition without said additive and does not undergo liquefaction, hardening, or other phase changes.

78. The conformal gel coating of claim 41, wherein one or more of the additives preferentially migrate to the coating/substrate interface to isolate the substrate from the remainder of the coating.

79. The conformal gel coating of claim 41, wherein the additive is a passivating agent that migrates and adsorbs onto the coating/substrate interface to inhibit catalytic activity from the substrate.

80. The conformal gel coating of claim 41, wherein one or more of the additives preferentially migrate to areas of the substrate where the coating is absent to protect the substrate from environmental effects.

81. A method of treating an electronic device with a gel coat, the method comprising:

applying the gel coat to the electronic device, the gel coat comprising a film forming agent and an additive,

the coating composition optionally further comprises at least one solvent, dye, pigment, or combination thereof.

82. The method of claim 81, wherein the electronic device comprises a printed circuit board.

83. The method of claim 82, wherein the gel coat is applied to a portion or all of the printed circuit board.

84. The method of claim 82, wherein the gel-coat covers a male component, a female component, or both of a connector in the electronic device without adversely affecting electrical performance of the printed circuit board.

85. The method of claim 81, wherein the gel-forming coating exhibits viscoelastic, viscoplastic, or elastohydroplastic flow properties.

86. The method of claim 81, wherein the gel-forming coating is deposited to achieve a thickness in the range of 25nm to 500 μιη.

87. The method of claim 81, wherein the gel-forming coating is applied by atomized or non-atomized spray, dip coating, film coating, spray, needle dispensing, knife coating, or ink jet printing, or a combination thereof.

88. The method of claim 81, wherein the film former, the additive, the pigment, or the dye are formulated separately in a solvent and applied in succession.

89. The method of claim 82, wherein the passivating agent-containing or passivating agent-rich formulation is first applied to the metal component of the printed circuit board, followed by the film-forming agent with optional additives.

90. The method of claim 89 wherein the antioxidant-containing or antioxidant-enriched formulation is applied last to create an oxygen barrier at the free coating interface.

91. The method of claim 82, wherein the coating is deposited at different thicknesses on different components of the printed circuit board depending on the environmental protection desired.

92. The method of claim 81, wherein the coating is applied on top and bottom of the device to provide complete environmental protection.

93. A substrate having a conformal gel coating comprising a film former and an additive, the coating optionally further comprising a solvent, dye, pigment, or combination thereof.

94. The substrate of claim 93, the substrate being an electronic device.

95. The substrate of claim 94, wherein the electronic device comprises one or more printed circuit boards.

96. The substrate of claim 94, wherein the electronic device is an assembled consumer electronic device or an automotive device.

97. The substrate of claim 94, wherein the electronic device comprises a male connector and a female connector having the conformal gel coating applied thereto.

98. The substrate of claim 93, wherein the conformal gel coating has a thickness of 25nm-500 μιη.