BE1025386B1 - Coating - Google Patents

Abstract

An electronic or electrical device or component thereof comprising a protective polymeric coating on a surface of the electronic or electrical device or component thereof, wherein the polymeric coating is obtainable by exposing the electronic or electrical device or component thereof to a plasma containing one or more saturated monomer compounds for a sufficient period of time to cause the protective polymer coating to form on a surface thereof; wherein the one or more saturated monomer compounds each have a melting point at standard pressure below 45 ° C and a boiling point at standard pressure below 500 ° C.

Description

Coating

FIELD OF THE INVENTION

This invention relates to protective coatings. In particular, although not exclusively, the invention relates to substrates with protective coatings formed thereon, as well as to methods for forming protective coatings on substrates.

BACKGROUND OF THE INVENTION

It is known that electronic and electrical devices are very sensitive to damage caused by contamination with liquids such as environmental fluids, in particular water. Contact with liquids, whether in the course of normal use or as a result of accidental exposure, can lead to a short circuit between electronic components, and irreparable damage to printed circuit boards, electronic chips, etc.

The problem is particularly acute in relation to small portable electronic devices, such as mobile phones, smartphones, pagers, radios, hearing aids, laptops, notebooks, tablet computers, phablets and personal digital assistants (PDAs) that can be exposed to significant liquid contamination when used indoors or outdoors in the presence of liquids. Such devices are also susceptible to accidental exposure to liquids, for example when falling into liquid or splashing.

Other types of electronic or electrical devices can be susceptible to damage primarily due to their location, for example outdoor lighting, radio antennas and other forms of communication equipment.

It is known that the application of a protective coating on electronic substrates presents particular difficulties. An electronic substrate can in principle be any electronic or electrical device or component that includes at least one exposed electrical or electronic contact point. Such substrates are particularly delicate, e.g., due to electrochemical migration, and require highly effective protection as a barrier and water-repellent against liquids, often on complex surfaces, e.g., print topographies.

It is known to apply conformal coatings to electronic or electrical devices by wet chemical techniques, such as brushing, spraying and dipping, to protect against moisture, dust, chemicals and extreme temperatures. Compliant coatings adopt the 3D shape of the substrate on which they are formed and cover the entire

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BE2017 / 5447 surface of the substrate. For example, it is known to apply relatively thick protective coatings on electronic substrates based on Parylene technology. A conformal coating thus formed typically has a thickness of 30-130 μm for an acrylic resin, epoxy resin or urethane resin and 50-210 μm for a silicone resin.

The use of wet chemical techniques to form these coatings has the disadvantage of the required use of solvents and associated environmental impact. In addition, wet chemical techniques only allow exposed areas of the device or component to be coated, so hidden areas, e.g. recesses behind components, can be left unprotected. Examples of such hidden areas on a mobile phone include the area under the RF shields, the screen FOG (flex on glass) connector, the inner parts of ZIF (Zero Insertion Force) connectors.

In addition, electrical or electronic contact points of such substrates may lose their function if covered with a too thick protective layer due to increased electrical resistance.

Since conformal coatings formed by wet chemical techniques are relatively thick, contact points are usually masked to prevent coating from depositing thereon. However, this leads to complex processing that is not practical on an industrial scale. Moreover, the relatively thick coating can cause clogging in areas such as rotating shafts. An alternative method for protecting electronic and electrical devices is the Splash-proof (TM) splash proof technology from P2i, where an ultra-thin water-repellent protective coating is applied to both the outside and the inside of a composite electronic or electrical device. This limits the penetration of liquids, while moreover preventing penetrated liquid from spreading inside the device. Thus, in the first place, it is prevented that the majority of a contamination with liquid penetrates into the device, while there is some extra protection inside the device that does not interfere with the functionality of contact points. However, since this technology relates to a liquid-repellent coating rather than a physical barrier, it generally only provides protection against splash liquid and not against immersion of the device in liquid.

WO2007 / 083122 discloses electronic and electrical devices having a liquid-repellent polymeric coating formed by exposure to pulsed plasma comprising a particular monomer compound, for a sufficient period of time to cause a polymeric coating to form on the surface of the electrical or electronic devices. In general, an article to be treated is placed in a plasma chamber together with material to be deposited in the gaseous state, a glow discharge in the

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BE2017 / 5447 chamber is ignited and a suitable voltage is applied which can be pulsed. This patent application relates to a liquid-repellent coating instead of a physical barrier.

There remains a need in the art for highly effective protective coatings without the disadvantages of coatings used by known methods. Such coatings can further improve the resistance of substrates to liquids and / or enable more efficient manufacture of protected substrates, in particular in the electronics industry. It is an object of the invention to provide a solution to this problem and / or at least one other problem of the prior art.

Explanations of the invention

According to an aspect of the present invention, an electronic or electrical device or component thereof is provided, comprising a protective polymeric coating on a surface of the electronic or electrical device or component thereof, wherein the polymeric coating is obtainable by exposing the electronic or electrical device or component thereof on a plasma comprising one or more saturated monomer compounds for a sufficient period of time to cause the protective polymer coating to form on a surface thereof; wherein the one or more saturated monomer compounds each have a melting point at standard pressure below 45 ° C and a boiling point at standard pressure below 500 ° C.

Preferably, each saturated monomer compound is a compound of formula (I):

wherein each of FL to R _{4 is} independently selected from hydrogen, halogen and an optionally substituted C 1 -C ₆ cyclic, branched or straight chain alkyl group and n is from 1 to 24.

The present invention provides a protective polymeric coating on a surface of the electronic or electrical device or component thereof by polymerizing saturated monomer compounds. The advantages of using a saturated monomer as a starting material for the protective polymeric coating stems from the fact that they are more stable than unsaturated monomers (and not like the unsaturated monomers polymerize), so that they can easily be stored and

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BE2017 / 5447 transported. For the same reason, there is no need to add free radical inhibitors (stabilizers) and there is no need to consider their effects on storage and on the polymerization process. In addition, since the saturated monomers are often less functionalized than unsaturated monomers, they can also be cheaper than unsaturated monomers.

High-energy conditions are needed to polymerize saturated monomers, i.e., monomers without a polymerizable structure such as a double or triple bond. This means that considerable fragmentation of the hydrocarbon takes place during the polymerization process, which leads to cross-linking of the monomers. Plasma polymerization using saturated molecules as described herein is not site-specific due to the absence of unsaturated bonds. This leads to cross-linked structures. The presence of a larger proportion of crosslinking in the polymer means that the polymeric coating is denser and provides a physical barrier for mass and electron transport (i.e., limits diffusion of water, oxygen, and ions).

Preferably the saturated monomer compound has a melting point at standard pressure lower than 40 ° C, optionally lower than 35 ° C, most preferably less than 30 Ό. Preferably, the saturated monomer compound has a boiling point at standard pressure below 450 ° C, optionally below 400 ° C, optionally below 350 ° C, most preferably below 300 ° C.

The value of n can be from 1 to 22, 1 to 18, 1 to 16, or in a preferred embodiment, n is from 8 to 14, optionally n is 12.

The halogen can be chlorine or bromine, but is preferably fluorine in accordance with RoHS regulations (Restriction of Hazardous Substances). The monomer can be a perfluoroalkane. The monomer can contain 1,2,3, 4, 5 or 6 fluorine groups.

In one embodiment, each of R 1 to R _{4 is} independently selected from hydrogen and an optionally substituted C 1 -C ₆ branched or straight chain alkyl group. The skilled person would be aware of possible substituents for the C 6 -C 6 cyclic, branched or straight chain alkyl group. Those skilled in the art will realize that any C 1 -C 6 cyclic, branched or straight-chain alkyl group may be substituted with one or more saturated functional groups. If the alkyl group is substituted, a preferred substituent is halogen, ie any of R 1 to R ₄ can be haloalkyl, preferably fluoroalkyl. An alkyl group can be substituted with one or more fluorine groups. Each of R 1 to R ₄ can be substituted with 1,2, 3, 4, 5 or 6 fluorine groups. Each of R 1 to R ₄ can be a perfluoroalkyl group. Each of the alkyl groups can also be substituted with one or more hydroxyl groups.

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Optionally, any C 1 -C 6 alkyl group can be independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, neopentyl, n-hexyl, isohexyl, and 3-methyl pentyl.

In a preferred embodiment, R 1 and R _{4 are} both methyl.

In a preferred embodiment, R ₂ and R _{3 are} each independently selected from hydrogen and methyl. In a preferred embodiment, each R ₂ and R _{3 is} hydrogen.

In one preferred embodiment, R 1 and R _{4 are} both methyl and each R ₂ and R _{3 is} hydrogen,

ie the monomer is a straight-chain alkane. In a particularly preferred embodiment, R 1 and R _{4 are} both methyl, each R ₂ and R _{3 is} hydrogen and n is from 8 to 14, most preferably 12.

The monomer can be a C 1 -C ₂ straight-chain alkane, a C 1 -C ₈ straight-chain alkane, a C ₉ C ₁₈ straight-chain alkane or a C ₁₃ -C ₁₆ straight-chain alkane. The monomer can be a C ₄ -C ₂₄ branched alkane, a C ₄ -C ₈ branched alkane, a C ₉ -C ₂₂ branched alkane or a C ₁₃ -C ₁₆ branched alkane. It will be appreciated that the maximum number of carbon atoms for a branched alkane monomer will be higher than the maximum number of carbon atoms for a straight-chain monomer to satisfy the requirement that the melting point of the monomer at standard pressure is less than 45 en and the boiling point at standard pressure is less than 500 Ό.

Preferably, the monomer is selected from methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,225 dimethylbutane, 2,3-dimethylbutane, n-heptane, 2-methylhexane, 3-methylhexane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 3ethylpentane, 2, 2,3-trimethylpentane, n-octane, 2- methylheptane, 3-methylheptane, 4-methylheptane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,3 dimethylhexane, 3,4-dimethylhexane, 3-ethylhexane, 2,2,330 trimethylpentane, 2,2,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane, 3ethyl-2-methylpentane, 3-ethyl-3-methylpentane, 2,2,3,3-tetramethylbutane, n- nonane and isomers thereof, n-decane and isomers thereof, n-undecane and isomers thereof, ndodecane and isomers thereof, n-tridecane and isomers thereof, n-tetradecane and isomers thereof, n-pentadecane and isomers thereof, and n-hexadecane and isomeric one of them. A particularly preferred monomer compound is n-tetradecane. 2,2,4,4,6,8,8 heptamethyl nonane is also suitable.

Table 1 gives a list of suitable straight chain alkane monomers and their corresponding melting and boiling points at standard (atmospheric) pressure.

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n n-Alkane melting point / ° C b.p. / ° C 1 methane -183 -161 2 ethane -172 -88 3 propane -188 -42.1 4 butane -138 -0.5 5 pentane -130 35-36 6 hexane -95 69 7 heptane -91 98 8 octane -57 125-127 9 nonane -53 151 10 dean -30 174 11 undecane -26 196 12 dodecan -9.6 215-217 13 tridecan -6- -4 110-112 14 tetradecan 5.5 252-254 15 pentadecane 8-10 270 16 hexadecane 18 287 17 hepttadean 20-22 302 18 octadecane 26-29 317 19 nonadecan 30-34 330 21 heneicosane 39-42 356

Table 1

Preferred chemical structures for some branched alkane monomers are shown below:

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Z6>. · <Yr '' W Ms

,. Λ r

V / 11 ✓ *

S., '- · y ..- r i V / ((> s.

mp S Ό bp 295 - ^! C xj z <

K'f bp 220 ^V C>: ic ^f

i. / 8 'x mp> · j l / 9 mp "-Μ" "C bp 298" Ό .- • L, * ·, .. · \ / 14

367 C • mpTS ^{: i} 'C bp 37Û 0 „, J.

\ Z "" S "

T r 'T

-'s ...

-23 ° G bp 274 "Ci:

mp mp = melting point; bp = boiling point

The plasma can comprise a single monomer compound. In this case, the coating 5 is formed by polymerization of the single monomer compound.

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Alternatively, the plasma may comprise two different monomer compounds. In this case, the coating is formed by polymerizing the two different monomer compounds to form a copolymer. For example, the plasma may comprise a monomer compound and a co-monomer compound, wherein the monomer and comonomer compounds have different chemical structures according to formula (I). More than two different monomer compounds can also be considered.

The use of two or more different monomer compounds allows the coating properties to be adjusted (e.g., hardness, surface finish and etching, and polymer growth at the substrate / coating interface). For example, for coatings in areas subject to wear, the co-monomer can be selected to create a stronger interface with the substrate surface and / or a top layer to protect the coating.

In a preferred embodiment, the protective polymeric coating is a physical barrier.

The term physical barrier is used in the sense that the coating protects the electronic or electrical device or component thereof by providing a physical barrier for masses of electron transport, which limits the diffusion of water, oxygen and ions with time / voltage.

The coating can form a surface defined by a static water contact angle (WCA) of at least 70 °. Coatings with a WCA of at least 90 ° can be described as liquid-repellent (typically water-repellent). In this case, the coating achieves liquid repellency in addition to providing a physical barrier. For fluorinated polymers, the coating can have a static water contact angle of at least 100 °. The contact angle of a liquid on a solid substrate gives an indication of the surface energy, which in turn illustrates the liquid-repellent properties of the substrate. Contact angles can be measured on a VCA Optima contact angle analyzer, using drops of 3 μΙ deionized water at room temperature.

In a particularly preferred embodiment, the protective polymeric coating is a conformal polymeric coating over a surface of the device or component thereof.

When the coating conforms, it means that it takes on the 3D shape of the electronic or electrical device or component thereof and substantially covers an entire surface of the device. This has the advantage of ensuring that the coating has sufficient thickness to provide optimum functionality over an entire surface of the device or component. The meaning of the term essentially covers an entire surface

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BE2017 / 5447 depend somewhat on the type of surface to be covered. For example, for some components it may be necessary to have complete coverage of the surface so that the component will function after immersion in water. However, for other components or housings, small holes in the cover can be tolerated.

Applicants have discovered that a conformal coating that forms a physical barrier can be formed at much lower thickness than achieved in the prior art. This new thinner coating offers the protection of a physical barrier with the use of less monomer and with a shorter processing time, which therefore has both ecological and economic advantages.

The coating of the present invention is sufficiently thin to prevent clogging in critical areas such as rotating shafts.

The coating of the present invention is thin enough to allow electrical connection to electrical contacts without prior removal of the coating, i.e. without the need for electrical contacts to be masked during the coating process. This is particularly advantageous for components such as ZIF (Zero Insertion Forcej connectors, headphone connections and SIM card slots.

Different connectors apply different forces to the contact point (and therefore coating) and may have different surface profiles in contact with the contact point (e.g. flat, round or pointed). Examples of suitable connectors include ZIF connectors, RF connectors, wipe contacts, contacts with high residual contact force (equilibrium force after insertion), spring connectors, headphone connectors and SIM card slots. For the purposes of the present invention, the fact whether an electrical connection can be made through a coating is determined using a ZIF or RF connector.

The protective polymeric coating may have a thickness of 50 to 10,000 nm, optionally 50 to 8000 nm, 100 to 5000 nm, preferably 250 nm - 5000 nm, most preferably 250 nm - 2000 nm. Coatings below 2000 nm show good results for connections to headphones through the coating. Coatings below 1000 nm show particularly good results with connections to spring connectors and SIM card slots through the coatings.

The protective polymeric coating can form a conformal physical barrier over substantially an outer and / or inner surface of the device. Thus, the protective polymeric coating can form a conforming physical barrier over substantially an entire outer surface of the electronic or electrical device or component thereof.

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In one embodiment, the electronic or electrical device or component thereof comprises a housing and the protective coating forms a conformal physical barrier over substantially an entire outer and / or inner surface of the housing and / or on surfaces of components within the housing.

In one embodiment, the electronic or electrical device or component thereof comprises a housing and the protective polymeric coating forms a conformal physical barrier over substantially an entire inner surface of the housing and / or surfaces of components within the housing. In this embodiment, suitable protection is provided by the coating on the inner surfaces; the outer surface of the housing does not have to be coated, which can be advantageous for cosmetic areas as well as reducing processing steps.

The use of plasma polymerization provides a coating of good thickness and quality of homogeneity and allows non-exposed areas on the electronic or electrical device or component thereof to be coated, for example, recesses behind components that would not be accessible using wet chemical techniques. In addition, the use of plasma polymerization has the advantage that it is a clean technique that does not require the use of solvents.

The coating can comprise one or more protective polymeric coating layers.

Preferably, the protective polymeric coating is electrically insulating.

In one embodiment, the electronic or electrical device or component can withstand immersion in up to 1 meter of water for more than 30 minutes without failure or corrosion while power is applied to the electronic or electrical device or component.

Optionally, when the protective polymeric coating is applied to a test circuit board (PCB), it has a resistance of 8 MOhm or higher when immersed in water and a voltage of at least 16 V / mm (e.g. 8 V over a 0.5 mm gap between electrodes) is applied for a minimum of 13 minutes.

In one embodiment, the coating is electrically insulating and the coating is sufficiently flexible that electrical connectors can be connected to the electronic or electrical device or component thereof and an electrical connection between the electrical

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BE2017 / 5447 connectors and electronic or electrical device or component thereof can be made without the need to first remove the coating.

Optionally, the coating is electrically insulating and a force of less than 100 g applied to the coating using a round probe with a diameter of 1 mm makes it possible to make an electrical connection to the electronic or electrical device or component thereof in the local environment is where the force is applied.

Optionally, the coating is electrically insulating and has a thickness of 150 nm to 1,000 nm and a force of less than 65 g applied to the coating using a round probe with a diameter of 1 mm makes it possible to make an electrical connection in the local environment of the coating where the force has been applied.

Optionally, the electronic or electrical device or component thereof comprises at least one electrical contact and wherein the at least one contact is covered by the coating.

The electronic or electrical device or component thereof is preferably selected from mobile telephones, smartphones, pagers, radios, sound and audio systems such as speakers, microphones, ringers and / or buzzers, hearing aids, personal audio equipment such as personal CD, cassette tape or MP3 players, televisions, DVD players including portable DVD players, VCRs, digital and other set-top boxes, computers and related components such as laptop, notebook, tablet, phablet, palmtop computers, personal digital assistants ( PDAs), keyboards, or instrumentation, game consoles, data storage devices, outdoor lighting systems, radio antennas and other communication equipment and printed circuit boards.

In preferred embodiments of the invention, the substrate may comprise or consist of an electronic component, e.g., a printed circuit board (PCB), a printed circuit board array (PCBA), a transistor, resistor or semiconductor chip. The electronic component can thus be an internal component of an electronic device, for example, a mobile telephone. The coatings of the invention are particularly valuable in preventing electrochemical migration in such components.

In a further aspect, the present invention provides a method for handling an electronic or electrical device or component according to any of the preceding claims, comprising:

exposing the electronic or electrical device or component thereof to a plasma comprising one or more saturated monomer compounds for a sufficient time

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BE2017 / 5447 time period to cause a protective polymer coating to form on a surface thereof; wherein the one or more saturated monomer compounds each have a melting point at standard pressure below 45 ° C and a boiling point at standard pressure below 500 ° C.

Preferably, each monomer is a compound of formula (I):

j Y

L 'J n wherein each of R; until R _{4 is} independently selected from hydrogen, halogen and an optionally substituted C 1 -C 6 branched or straight chain alkyl group and n is from 1 to 24.

The monomer compound is as defined in detail above.

Optionally, the coating is built up in successive layers.

The plasma can comprise one monomer compound. In this case, the coating is formed by polymerization of the single monomer compound.

Alternatively, the plasma may comprise two different monomer compounds. In this case, the coating is formed by polymerizing the two different monomer compounds to form a copolymer. For example, the plasma may comprise a monomer compound and a co-monomer compound, wherein the monomer and comonomer compounds have different chemical structures according to formula (I). More than two different monomer compounds can also be considered.

The coating can comprise one or more coating layers, the total thickness of the one or more coating layers being within the range according to the first aspect. Alternatively, the coating may comprise one or more coating layers, the thickness of each coating layer being within the range of the first aspect.

Ideally, the monomer is gaseous or liquid at room temperature so that it can be delivered to the plasma chamber.

The plasma is typically formed by applying a radio frequency signal to the one or more monomer compounds. Suitable plasmas for use in the methods of the invention include non-equilibrium plasmas such as those generated by radio frequencies (Rf),

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BE2017 / 5447 microwaves or direct current (DC). They can operate at atmospheric or sub-atmospheric pressures as known in the art. In particular, however, they can be generated by radio frequencies (Rf).

The plasma can be a pulsed wave (PW) plasma and / or a continuous wave (CW) plasma.

The coating is preferably substantially free of holes to provide a physical barrier. Preferably ΔΖ / d is <0.15, where ΔΖ is the average height variation, i.e. the surface profile measured on an AFM line scan, and d is coating thickness. The value of ΔΖ / d tells the extent to which defects on the surface of the coating extend into the coating, i.e. the percentage value of the depth of defect over the total coating thickness. For example, ΔΖ / d = 0.15 means that the cavities on the surface extend only down to 15% of the coating thickness. A coating with a ΔΖ / d <0.15 is defined herein as substantially without holes.

The coating can have a higher density than that of the corresponding monomers from which it is formed. For example, the increase in density may be approximately 0.1 g / cm ³ . The increase in density is explained by a highly cross-linked coating. The high density of the coating improves the barrier properties of the coating.

The process parameters may include, for example, power, monomer flow rate, and monomer flow to power ratio.

Preferably, the flow rate of the manamer is at standard temperature and pressure of

0.2 to 50, preferably 0.2 to 10 sccm, most preferably 0.25 to 1.0 sccm.

In a particularly preferred embodiment, the ratio of power to monomer flow rate is from 5 to 70 watts / sccm, optionally 40 to 70 watts / sccm, optionally 30 to 50 watts / sccm.

The step of exposing the electronic or electrical device or component thereof to a plasma can take place in a reaction chamber.

The step of exposing the electronic or electrical device or component thereof to a plasma can include a two-step process, the first and second steps comprising different plasma conditions, for example, a first continuous wave (CW) step and a second pulsed (PW) step.

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The continuous wave (CW) deposition step has been found to act as a substrate priming step which optimizes the performance of the coating. Applicants have discovered that incorporation of a CW step optimizes the interface between the substrate surface and growing coating, causing both some etching of the substrate surface and growth of the polymer coating. Inclusion of the CW deposition step leads to homogeneous growth of the coating and minimizes the chance of defects forming in the coating.

The pulsed (PW) deposition step has been found to be important in achieving good penetration of the coating in hard-to-reach areas. The applicants have surprisingly discovered that the quality and thickness of the coating on inner surfaces can be optimized by adjusting the flow and power parameters. Increased power provides good quality coatings with the desired functionality on inner surfaces. Increased flow provides good quality coatings with the desired functionality on outer surfaces.

The flow rate of the monomer compound into the chamber can be lower (on a per volume basis of the chamber) than in the case of unsaturated monomers. Surprisingly, it has been found that high ratios of monomer flow capability facilitate the formation of polymeric coatings with desired barrier properties, even at thicknesses that offer low electrical resistance.

The exact flow rate of the monomer compound into the chamber may depend to some extent on the nature of the specific monomer compound used, the nature of the substrate, and the desired properties of the protective coating. In some embodiments of the invention, the monomer compound is introduced into the chamber at a gas flow rate in the range of 0.2 to 50 sccm, preferably 0.2 to 10 sccm, and most preferably in the range of 0.25 to 0.5 sccm, although this will depend on room volume. For a 2.5L chamber, the gas flow rate can be in the range of 0.3 to 0.5 sccm. The monomer gas stream is calculated from the liquid monomer stream since the monomer in the chamber acts as an ideal gas.

For pulsed plasmas, higher average powers can be achieved by using higher peak powers and varying the pulsed regime (ie on / off times).

From a further aspect, the invention relies on a method of forming a coating on an electronic or electrical device or component thereof, which method comprises: exposing the substrate in a chamber to a plasma comprising a monomer compound, preferably a pulsed plasma, during one

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BE2017 / 5447 sufficient time period for a protective polymer coating to form on the substrate, wherein during the exposure of the substrate the pulsed plasma has a peak power (e.g., on-phase) of at least 8 W / liter.

In such a method, the peak power density of the plasma is very much higher than that described in WO2007 / 083122. It has been found that this high power density of the plasma surprisingly facilitates the formation of polymeric coatings with desired liquid-repellent and / or barrier properties, even at thicknesses that offer a low electrical resistance. This is due to the increased cross-linking and / or fragmentation that occurs at higher powers.

The exact peak power density of the plasma depends to a certain extent on the nature of the specific monomer compound used, the nature of the substrate and the desired properties of the protective coating. In some embodiments of the invention, the plasma may have a peak on-phase power density in the range of 3 to 30 W / liter, for example in the range of 8 to 22 W / liter.

In one embodiment, the plasma is a pulsed plasma in which pulses are applied in a sequence that yields a time-on: time-out ratio in the range of 0.5-0.001. For example, the time-on = 35-45 ps and time-off = 0.1 ms to 10 ms, for example 0.5 ms. This pulsing regime gives a much higher average power than with known techniques, for example as described in WO2007 / 083122, which contributes to the increased crosslinking and / or fragmentation of the obtained polymer coating.

From a further aspect, the invention relies on a method of forming a coating on an electronic or electrical device or component thereof, which method comprises: exposing the substrate in a chamber to a plasma comprising a monomer compound, preferably a continuous plasma for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during continuous exposure of the substrate the continuous plasma has a power density of at least 8 W / liter.

From a further aspect, the invention relates to a method for forming a coating on an electronic or electrical device or component thereof, which method comprises the following: exposing the electronic or electrical device or component thereof in a chamber to a plasma comprising a monomer compound, preferably a pulsed plasma, for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during the

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BE2017 / 5447 exposure of the substrate, the pulsed plasma has a peak power to flow ratio between 5 to 200 W / sccm, more preferably 40-70 W / sccm, most preferably 60 Watt / sccm.

It has been found that this range of power-to-flow ratio surprisingly facilitates the formation of polymeric coatings with desired liquid-repellent and / or barrier properties, even at low thicknesses.

From a further aspect, the invention relies on a method for forming a coating on an electronic or electrical device or component thereof, the method comprising the following: exposing the electronic or electrical device or component thereof in a chamber to a plasma comprising a monomer compound, preferably a continuous plasma, for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during the exposure of the substrate the continuous plasma has a ratio of power to flow between 5 to 200

W / sccm, preferably 40-70 W / sccm, preferably 60 Watt / sccm.

The step of exposing the electronic or electrical device or component thereof to a plasma can include a pulsed (PW) deposition step. Alternatively or additionally, the step of exposing the electronic or electrical device or component thereof to a plasma may include a continuous wave (CW) deposition step.

The aspects of the invention each provide methods that facilitate the formation of highly effective protective coatings that can be applied to electronic substrates without adversely interfering with contact points. An advantage is that the resulting coating is sufficiently flexible that electrical connectors can be connected after coating the device during or after fabrication and assembly. In one embodiment, the method comprises the step of connecting electrical connectors to the electronic or electrical device or component thereof after the coating has been applied. This has the advantage that the electrical connectors can be easily connected to the electronic or electrical devices or component thereof after coating the device or component during manufacture or assembly. In an alternative embodiment, the electrical connectors can be connected to the electronic or electrical device or component thereof before the coating is applied.

In particular, the features of the aspects of the invention operate in synergy and lead to preferred embodiments of the invention when combined. All such combinations, with or without the preferred and optional functions listed herein, are explicitly considered in accordance with the invention.

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In all aspects of the invention, the exact conditions under which the protective polymeric coating is effectively formed will vary depending on factors such as, but not limited to, the nature of the monomer compound, the substrate, and the desired properties of the coating. These conditions can be determined using routine methods or preferably using the techniques and preferred features of the invention described herein, which operate in particular synergy with the invention.

Suitable plasmas for use in the methods of the invention include non-equilibrium plasmas such as those generated by radio frequencies (Rf), microwaves or direct current (DC). They can operate at atmospheric or sub-atmospheric pressures as known in the art. In particular, however, they can be generated by radio frequencies (Rf).

Different forms of equipment can be used to generate gaseous plasmas. In general, these include containers or plasma chambers in which plasmas can be generated. Specific examples of such equipment are described, for example, in WO2005 / 089961 and WO02 / 28548, the contents of which are incorporated herein by reference, but many other conventional plasma-generating equipment are available.

In general, the substrate to be treated is placed in the plasma chamber together with the monomer compound, a glow discharge is ignited in the chamber, and a suitable voltage is applied. The voltage can be continuous or pulsed. Monomer can be introduced from the start or after a period of prior plasma continuous power.

The monomer compound will suitably be in a gaseous state in the plasma. The plasma may simply comprise a vapor of the monomer compound if present. Such vapor can be formed in situ, the compounds being introduced into the chamber in liquid form. The monomer can also be combined with a carrier gas, in particular an inert gas such as helium or argon.

In preferred embodiments, the monomer can be delivered to the chamber by means of an aerosol device such as a nebulizer or the like, as described, for example, in WO2003 / 097245 and WO003 / 101621, the contents of which are incorporated herein by reference.

In such an arrangement, a carrier gas need not be necessary, which advantageously helps to achieve high flow rates.

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In some cases, a prior plasma continuous power may be created in the chamber for, for example, from 10 seconds to 10 minutes, e.g. This can act as a surface pre-treatment step, so that the monomer compound easily adheres to the surface, so that when polymerization takes place, the coating grows on the surface. The pre-treatment step can be performed before monomer is introduced into the chamber, for example in the presence of inert gas, or simply in a residual atmosphere. Monomer can then be introduced into the chamber to allow polymerization to take place, whereby the plasma is either switched to a pulsed plasma, continued with a continuous plasma or a sequence of both continuous and pulsed plasma is used.

In all cases, a glow discharge is suitably ignited by applying a high-frequency voltage, for example at 13.56 MHz. This is suitably applied with electrodes that are inside or outside the chamber.

Gases, vapors, or aerosols can be drawn or pumped into the plasma chamber or plasma region. Particularly when a plasma chamber is used, gases or vapors may be drawn into the chamber due to a reduction in the pressure in the chamber caused by the use of an evacuation pump, or they may be pumped or injected into the chamber as is customary when working with liquid.

Suitably the gas, vapor or gas mixture can be supplied at a rate of at least 0.04 sccm, preferably 0.2 to 50 sccm, preferably 0.2 to 10 sccm and most preferably in the range of 0.25 up to 0.5 sccm, although this will depend on the room volume. These amounts can be scaled up to larger systems on a chamber volume basis in accordance with the teachings described herein.

Polymerization is suitably carried out using vapors of the monomer compound, which are maintained at pressures of 0.1 to 200 m Torr, suitably at about 15-150 m Torr, preferably 30 to 60 m Torr, most preferably about 40 m Torr.

The applied fields may preferably provide a relatively high peak power density, e.g., as defined above in the method of the invention. The pulses can also be applied in a sequence that produces a lower average power, for example in a sequence in which the time-on: time-out ratio is in the range of 20: 100 to 20: 20,000. Sequences with shorter time-out periods may be preferred to maintain good power density. One example of a sequence is a sequence in which power is on for 20 to 50 microseconds, for example 30 to 40 microseconds, such as about 36 microseconds, and off for

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BE2017 / 5447 to 30 milliseconds, for example 5 to 15 milliseconds, such as 6 milliseconds. It has been found that this can be especially advantageous when the monomer is a compound of formula (I).

Preferred average powers obtained in this way in a three-liter chamber were in the range of 0.05 to 25 W. In some embodiments, relatively low average powers are preferred, e.g., in the range of 0.1 to 5. W, such as 0.15 to 0.5 W in a three-liter chamber. Higher average powers, for example more than 5 W, have been shown to have the advantage of assisting with monomer fragmentation. These ranges can be increased or decreased on a volume basis for larger or smaller chambers and will depend on the selected peak power and the selected pulse sequence.

The process temperatures, e.g., measured within the chamber, can be ambient temperature or preferably slightly above ambient temperature, such as in the range of 25 to 60 ° C, e.g. 35 to 55 Ό. In some embodiments, the process temperature is kept below 40 ° C. It is preferable to keep the temperature in the coating deposition process within a range that will not damage the electronic or electrical device or component thereof. This keeps the temperature below 50 voor for mobile phones.

Suitably, a used plasma chamber can be of sufficient volume to accommodate multiple substrates, especially when they are small in size, for example, up to 20,000 PCB can be easily processed simultaneously with equipment of the correct size. A particularly suitable apparatus and method for manufacturing coated substrates according to the invention are described in WO2005 / 089961, the contents of which are incorporated herein by reference.

The dimensions of the chamber will be chosen to accommodate the whole of the specific substrate to be treated. For example, generally cubic chambers may be suitable for a variety of applications, but if required, elongated or rectangular chambers may be constructed or even cylindrical or of any other suitable shape. The volume of the chamber can for example be at least 1 liter, preferably at least 8 liters. In some applications, relatively small chambers with a volume of up to 13 liters or up to 25 liters are preferred. For large-scale production, the volume of the chamber may suitably be up to 400 liters or higher. The chamber may be a closable container to allow batch processes, or may include inlets and outlets for substrates so that it can be used in a continuous process. Particularly in the latter case, the pressure conditions required to create a plasma discharge within the chamber are maintained using high volume pumps, such as

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BE2017 / 5447 is common in, for example, a device with a whistle leak. However, it may also be possible to process certain substrates at atmospheric pressure or close thereto, whereby flute leaks are not necessary.

Advantageously, electronic or electrical contact points of the substrate need not be masked during the treatment, in particular for coating with a thickness below 5 μm, more preferably below 2 μm. Indeed, in one embodiment of the invention, these contacts are not masked during the formation of the coating by any of the methods described herein, leading to an advantageously simplified process.

More generally, from a further aspect, the invention relates to a substrate with a polymeric coating formed by any of the methods described herein. The invention also includes coated substrates obtainable by any of the methods described herein.

One particular advantage of the invention is that electronic or electrical devices as a whole can be made resistant to liquids, even during complete immersion, by coating only internal components such as PCBs, whereby an external coating is no longer necessary. Thus, from a further aspect, the invention relates to an electronic or electrical device, for example a mobile telephone, comprising a housing and one or more internal electronic or electrical components having a coating thereon formed by any of the methods described herein. Advantageously, the housing does not have to include a coating. The device can advantageously meet standard IEC 60529 14.2.7 (IPX7).

More generally, any of the coated electronic substrates described herein can preferably continue to function even after complete immersion in water for at least 2 minutes, preferably at least 5 minutes. The electronic substrate will preferably continue to function for at least 30 minutes or more, preferably at least two days.

Aspects of the invention relating to methods of forming a coating on an electronic or electrical device or component thereof can be carried out using the monomers mentioned for the first aspect of the invention.

As used herein, the term gaseous refers to gases or vapors, alone or in admixture, and optionally to aerosols.

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As used herein, the term protective polymeric coating refers to polymeric layers that provide some protection against fluid damage, for example, by forming a barrier and optionally by being fluid-repellent (such as oil and / or water-repellent). Sources of liquids against which the substrate is protected include environmental liquids such as water, in particular rain, and liquids that are accidentally spilled.

As used herein, the expression during exposure of the substrate refers to a period in which the substrate is within the chamber together with the plasma. In some embodiments of the invention, the term may refer to the entire period in which the substrate is within the chamber together with the plasma.

Through the description and claims of this specification, the words include and include and variations of the word, for example including and including, have the meaning including but not limited to, and do not exclude other groups, additives, components, integers or steps. Moreover, the singular includes the plural unless the context requires otherwise: in particular when the indefinite article is used, the specification is to be considered as both plural and singular, unless the context requires otherwise.

Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Other features of the invention will become apparent from the following examples. In general, the invention extends to any new feature, or to any new combination of features described in this specification (including all appended claims and drawings). Thus, it is to be understood that features, numbers, characteristics, compounds, chemical units or groups described in connection with a specific aspect, embodiment or example of the invention are applicable to any other aspect, embodiment or example described herein. unless this is incompatible with it. In addition, unless otherwise specified, any feature described herein may be replaced by an alternative feature that serves the same or similar purpose.

When upper and lower limits are mentioned for a property, for example the concentration of a monomer, then a range of values defined by a combination of each of the upper limits with each of the lower limits can also be implied.

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The present invention will now be further described with reference to the following non-limiting examples and the accompanying illustrative drawings, in which: Figure 1 illustrates the electrical testing device for determining the resistance of the coating;

Figure 2 shows a tapping mode image of a 1700 nm thick coating prepared as described in Example 1 over 1x1 μm ² field of view (top left), a 5x5 μm ² field of view (top right), a representative contour line that changes the height (z axis) of the indicates coating (bottom left) and a phase image indicating complete substrate coverage (bottom right); RMS roughness of the coating is 0.4 nm and Δζ / d = 0.0006.

Example 1

Process design and parameters

Plasma polymerization experiments were performed in a cylindrical glass reactor vessel with a capacity of 2.5 liters. The vessel was in two parts coupled with a Viton O ring to seal the two parts together under vacuum. One end of the reactor was connected to a liquid flow controller, which was heated at 70 ° C, and this was used to deliver monomer at a controlled flow rate.

The other end of the reactor was connected to a metal pump pipeline equipped with pressure gauges, pressure control valve, liquid nitrogen trap and a vacuum pump. A copper coil electrode was wound around the outside of the reactor (11 turns of 5 mm diameter pipe) and connected to an RF power supply via an L25 C matching network. For pulsed plasma deposition, the RF power supply unit was controlled by a pulse generator.

The monomer used was n-tetradecane (CAS No. 16646-44-9), a saturated monomer according to the present invention

The reactor was evacuated to the basic pressure (typically <10 mTorr). The monomer was delivered to the chamber using the flow controller, with a monomer gas flow of 0.4 sccm. The chamber was heated to 45 ° C. The pressure in the reactor was kept at 30 mTorr. The plasma was produced using RF at 13.56 MHz and the process usually consisted of two steps; the continuous wave (CW) plasma and the pulsed wave (PW) plasma. The CW plasma was for 2 minutes and the duration of the PW plasma varied in different experiments. The peak power setting was 30 W, and the pulse conditions were time on (T _on ) = 37 ps and time off (T _off ) = 0.5 ms. At the end of the deposition, the RF power was turned off, the flow controller stopped and the room

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BE2017 / 5447 pumped empty to basic pressure. The chamber was vented to atmospheric pressure and the coated samples removed.

Two test PCBs and two Si waffles were used for each experiment. The Si wafers allow physical properties of the coating formed to be measured, e.g. AFM for surface morphology. The metal traces of the test PCBs were gold clad copper. The Si waffles were placed on the top front of the PCBs.

The process parameters for the experiments are shown in Table 2.

Example 2

Resistance at fixed voltage in time

This test method has been developed to evaluate the ability of different coatings to provide an electrical barrier on printed circuit boards and to predict the ability of a smartphone to pass the IEC 60529 14.2.7 (IPX7) test. The method has been developed to be used with tap water. This test includes the measurement of the current (IV) characteristics of a standardized PCB (water) in water. The PCB is designed with a distance of 0.5 mm between the electrodes to be able to judge when electrochemical migration occurs over the traces in water. The degree of electrochemical activity is quantified by measuring current; low current is indicative of a coating with good quality. The method appears to be very effective at differentiating between different coatings. The performance of the coatings can be quantified, for example, as a resistance at 4, 8 V and 21 V. The measured resistance on the untreated test device is approximately 100 ohms when a voltage of 8 V is applied.

The coated PCB to be tested is placed in a beaker with water and connected to the electrical test device as shown in Figure 1. The plate 10 is horizontally and vertically centered in the beaker 12 with water 14 to minimize effects of local ion concentration (vertical location of the plate with water is very important; the water level must be up to the blue line). When the circuit board is connected, the power source is set to the desired voltage and the current is monitored immediately. The applied voltage is, for example, 8 V and the PCB is kept at the set voltage for 13 minutes, the current being continuously monitored during this period.

The coating formed by the process parameters shown in Table 2 is tested and the results are shown in Table 3. It has been found that when coatings have resistance values

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BE2017 / 5447 higher than 8 MOhm, the coated device successfully passes an IPX7 test. The nature of the device that is covered (for example the type of smartphone) will influence the test, for example by variations in materials, intrusion points, power consumption, etc.

Critical power (Fc)

The electrical conductivity of a coating can change considerably when a compressive voltage is applied to the coating. The change in the electrical conductivity depends on the amplitude of the stress experienced by the coating, the amount of defects and the type of polymer matrix of the coating. This behavior is explained on the basis of the formation or destruction of a conductive network, which further depends on the viscosity (stiffness) of the polymer matrix. To evaluate the ability of the coating to provide electrical contact under a relatively low force, a contact force test is performed.

The contact force test is an electrical test procedure that includes measuring the critical force (Fc) or pressure (Pc) to be applied to the insulating coating through a flat probe to cause electrical breakthrough through the coating. The test can be used either on smart phone PCBs or on strip plates (Test PCBs) that are placed as testimony samples during processes.

The test uses a flat probe of 1 mm in diameter (or a spherical probe with a diameter of 2 mm) that makes contact with the flat surface of the film. The probe is mounted on a support leg and the arrangement is such that variations in the force applied by the probe to the surface of the sample are immediately recorded by a scale (or load cell) on which the sample is placed. With this arrangement, the resolution in applied pressure is approximately 15 kPA (force 5 g).

The normal procedure is to manually increase the force applied by the probe to the flat surface of the sample, taking into account the resistance between the probe and the conductive substrate. The force is manually or automatically increased to the point (Fc) when a film breakthrough occurs.

This test allows the electrical insulation properties of the sample to be analyzed at a number of different points across the surface, thereby providing an idea of the uniformity of the surface layer.

The Fc value for the coated PCB coating formed in Example 1 is shown in Table 3.

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Coating thickness

The thickness of the coatings formed in Example 1 was measured with a spectroscopic reflectometry device (Filmetrics F20-UV) using optical constants verified by spectroscopic elipsometry.

Spectroscopic reflectrometry

Thickness of the coating is measured with a Filmetrics F20-UV spectrometer reflectorometry. This instrument (F20-UV) measures the characteristics of the coating, the reflection of light from the coating and the analysis of the resulting reflection coefficient spectrum and a range of wavelengths. Light reflected from different interfaces of the coating can be in or out of phase so that these reflections add or subtract, depending on the wavelength of the incident light and the thickness and index of the coating. The result is intensity oscillations in the reflection coefficient spectrum that are characteristic of the coating.

To determine the thickness of the coating, the Filmetrics software calculates a theoretical reflection coefficient spectrum that corresponds as much as possible to the measured spectrum. It starts with an initial estimate of what the reflection coefficient spectrum should look like, based on the nominal coating stack (layered structure). This includes information about the thickness (accuracy 0.2 nm) and the refractive index of the different layers and the substrate from which the sample is composed (refractive index values can be derived from spectroscopic ellipsometry). The theoretical reflection coefficient spectrum is then adjusted by adjusting properties of the coating until a best fit with the measured spectrum is found. Measured coatings must be optically smooth and fall within the thickness range of 1 nm to 40 μm.

Surface morphology

The surface morphology of the coatings is measured using atomic force microscopy (AFM). Analyzes are performed with a Veeco Park Autoprobe AFM instrument used in tapping imaging mode, using Ultrasharp NSC12, diving board levers with spring constants in the range of 4-14 N / m, and with resonance frequencies in the range of 150-310 kHz . A high aspect ratio probe with a radius of curvature on the tipapex of <10 nm and aperture angle <20 ° was used. Fields of view of 5x5 and 1x1 μm ² were shown, with the larger field of view being more informative. Surface roughness, RMS (root mean square), was calculated by standard software, for each field of view. The images obtained were 256 x 256 pixels in all cases.

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Two parameters can be extracted from the AFM morphological analysis of the coatings; (a) the RMS roughness (r) of the coating and b) the ratio ΔΖ / d where d is the thickness of the coating and ΔΖ is explained below.

Figure 2 shows a tapping mode image via 1x1 μm ² field of view of a specimen example (thickness d = 1700 nm) prepared according to Example 1 (left) and a contour line plot showing the data for the calculation of RMS roughness (right). The ΔΖ value indicated on the plot is taken over an area of the graph that represents most of the coating. Peaks that are above the ΔΖ range indicate large particles and troughs that fall below the ΔΖ range show cavities or holes in the coating. The width of the peaks also gives an indication of the particle size.

For the sample in Table 3, RMS roughness (r) was 0.4 nm and ΔΖ = 1 ± 0.2 nm giving ΔΖ / d = 0.0006.

It has been shown that ΔΖ / d <0.15 indicates a hole-free coating. Morphological parameters are good indicators for hole-free coatings. However, this property alone does not take into account the high performance of the coating.

After examination, the coatings were found to be compliant and the fact that all coatings either exceed the IPX7 test or get close to it is an indication that they form physical barriers. The use of plasma polymerization to deposit the coating has the advantage that the coating can be made thick enough to provide a physical barrier while being significantly thinner than prior art conformal coatings. This thickness range has the advantage that the coating is sufficiently thick to form a physical barrier and yet is thin enough to allow electrical connections to be made without first removing the coating.

The use of plasma polymerization also has the advantage that good intrusion of the monomer during the plasma polymerization technique ensures that the coating covers all desired areas, for example the entire outer surface. When the electronic or electrical device comprises a housing, the entire inner surface of the housing can be coated (by exposing the open housing to the plasma) to protect the electronic components in the housing when the device is assembled.

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CW time 2 min Taan 37 ps Spout 0.5 ms monomer pressure 30 mTorr PW / CW power 30 watts monomer flow rate 0.40 sccm (STP) Room T 45 ° C PW time 45 mins power / volume 12 watts / liter power / flow 75 watts / sccm monomer volume / min 0.005 ml / min

Table 2: Process parameters for a coating formed from n-tetradecane

thickness (d) Si 968 nm thickness (d) SB 1135 nm R at 8 V for 13 min 4.78E + 07 Ω R / d (13 min) 4.21 E + 04 Ω / nm Critical power 60 g RMS roughness (AFM) 0.4 nm ΔΖ (AFM) 1 ± 0.2 nm

Table 3: Coating properties of a coating formed from n-tetradecane

Claims (26)

An electronic or electrical device or an electronic or electrical component thereof, comprising a conforming, protective, liquid-repellent A polymeric coating on a surface of this device or component, wherein the polymeric coating is obtainable by exposing this device or component to a plasma comprising one or more saturated monomer compounds for a sufficient period of time to cause this coating to form on a surface thereof; wherein the one or more saturated monomer compounds each have a melting point at 10 have a standard pressure of less than 45 ° C and a boiling point at a standard pressure of less than 500 ° C and in which this coating is a physical barrier for mass and / or electron transport, so that this device or component is immersed in maximum 1 meter of water can withstand for more than 30 minutes without failure or corrosion while power is applied to this device or component. The device or component of claim 1, wherein the protective polymeric coating is defined by a static water contact angle (WCA) of at least 90 °. 20 The device or component of claim 1 or 2 wherein said device or component comprises a housing and wherein the coating forms a conformal polymeric coating over substantially an entire outer and / or inner surface of the housing. The device or component of any one of the preceding claims, wherein it Device or component comprises a housing and wherein the protective polymeric coating forms a conforming physical barrier over substantially an entire outer surface of components within the housing. The device or component of any one of the preceding claims wherein the Coating comprises two or more protective polymeric coating layers. The device or component of any one of the preceding claims, wherein the protective polymeric coating has a thickness of 50 nm-10000 nm. 35 The device or component of claim 6, wherein the coating has a thickness in the range of 100 nm to 5000 nm. The device or component of claim 7, wherein the coating has a thickness in the range of 250 nm to 2000 nm. 2017/5447 BE2017 / 5447 The device or component of any one of the preceding claims, wherein the coating is electrically insulating. The device or component of any preceding claim, wherein the coating has a resistance of 8 MOhm or higher when immersed in water and a voltage of at least 16 V / mm is applied for at least 13 minutes. The device or component according to any of the preceding claims, wherein the coating is electrically insulating and wherein the coating is sufficiently flexible that electrical connectors can be connected to this device or component and an electrical connection between the electrical connectors and the device or component can be made without the need to first remove the coating. The device or component according to any of the preceding claims, wherein the coating is electrically insulating and wherein a force of less than 100 g applied to the coating using a round probe with a diameter of 1 mm makes it possible to make an electrical connection with the device or component in the local environment where the force has been applied. The device or component of any one of the preceding claims, wherein the coating is electrically insulating and has a thickness of 150 nm to 1000 nm and wherein a force of less than 65 g applied to the coating using a round probe with a 1 mm diameter makes it possible to make an electrical connection in the local environment where the force is applied. The device or component of any one of the preceding claims, wherein said device or component comprises at least one electrical contact and wherein the at least one contact is covered by the coating. The device or component according to any of the preceding claims, wherein the device or component is selected from mobile phones, smartphones, pagers, radios, sound and audio systems such as speakers, microphones, ringers and / or buzzers, hearing aids, personal audio equipment such as personal CD, cassette tape or MP3 players, televisions, DVD players including portable DVD players, VCRs, digital and other set-top boxes, computers and related components such as laptop, notebook, tablet, phablet, palmtop computers, personal digital assistants (PDAs), keyboards, or instrumentation, game consoles, 2017/5447 30 BE2017 / 5447 data storage devices, outdoor lighting systems, radio antennas and other communication equipment and printed circuit boards. The device or component of any one of the preceding claims, wherein the saturated monomer compound or each saturated monomer compound is a compound of formula (I): wherein each of FL to R _{4 is} independently selected from hydrogen, halogen and an optionally substituted C 1 -C 6 cyclic, branched or straight chain alkyl group and n is from 1 to 24. The device or component of claim 16, wherein n is from 1 to 16. The device or component of claim 16, wherein n is from 8 to 14. The device or component of any preceding claim, wherein the monomer is selected from methane, ethane, propane, n-butane, isobutane, npentane, isopentane, neopentane, n-hexane, 2-methylpentane, 3-methylpentane , 2,2-dimethylbutane, 2,3-dimethylbutane, n-heptane, 2-methylhexane, 3-methylhexane, 2,2dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 3ethylpentane, 2 , 2,3-trimethylpentane, n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,3-dimethylhexane, 3 , 4-dimethylhexane, 3-ethylhexane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane, 3-ethyl-2-methylpentane, 3-ethyl -3-methylpentane, 2,2,3,3-tetramethylbutane, n-nonane and isomers thereof, n-decane and isomers thereof, n-undecane and isomers thereof, n-dodecane and isomers thereof, n-tridecane and isomers thereof, ntradecane and isomers thereof n, n-pentadecane and isomers thereof, and nhexadecane and isomers thereof. A method of treating a device or component according to any of the preceding claims, comprising: 2017/5447 BE2017 / 5447 exposing this device or component to a plasma comprising one or more saturated monomer compounds for a sufficient period of time to cause a protective polymer coating to form on a surface thereof; The method of claim 20, wherein the flow rate of the monomer at standard temperature and pressure is 0.2-50 sccm. The method of claim 20 or 21, wherein the ratio of power to flow rate of the monomer is from 5 to 70 watts / sccm. The method of any one of claims 20 to 22, wherein the coating is built up in successive layers. The method of any one of claims 20 to 23, wherein the plasma is formed by applying a radio frequency signal to the one or more monomer compounds, the one or more monomer compounds being in the gaseous state. The method of any one of claims 20 to 24, wherein the plasma is a pulsed wave plasma. The method of any one of claims 20 to 24, wherein the plasma is a continuous wave plasma.