阅读说明：本技术 带有聚合物纳米涂层的基材及形成聚合物纳米涂层的方法 (Substrate with polymer nanocoating and method of forming polymer nanocoating ) 是由 R·C·弗雷泽 内尔·波尔特 于 2020-02-21 设计创作，主要内容包括：本发明涉及一种带有聚合物纳米涂层的基材及形成聚合物纳米涂层的方法。该方法包含使该基材暴露于包含一种或多种不饱和单体物种的等离子体足够允许在该基材上形成该涂层的一段时间。该一种或多种不饱和单体物种包含(i)芳香族部分和(ii)羰基部分。该一种或多种不饱和单体物种还包含交联试剂。(The invention relates to a substrate with a polymer nano-coating and a method for forming the polymer nano-coating. The method comprises exposing the substrate to a plasma comprising one or more unsaturated monomeric species for a period of time sufficient to allow the coating to form on the substrate. The one or more unsaturated monomer species comprise (i) an aromatic moiety and (ii) a carbonyl moiety. The one or more unsaturated monomer species further comprise a crosslinking agent.)

1. A substrate bearing a polymeric nanocoating, wherein said coating comprises (i) an aromatic moiety and (ii) a carbonyl moiety.

2. The substrate of claim 1, wherein the thickness of the polymeric nanocoating is 15,000nm or less.

3. The substrate of claim 1 or 2, wherein the thickness of the polymeric nanocoating is 1nm or more.

4. The substrate of any one of the preceding claims, wherein the polymeric nanocoating is free of fluorine.

5. The substrate of any one of the preceding claims, wherein the polymeric nanocoating is halogen-free.

6. The substrate of any one of the preceding claims, wherein the aromatic moiety comprises an optionally substituted phenyl group.

7. A method for forming a polymeric nanocoating on a substrate, the method comprising exposing the substrate to a plasma comprising one or more unsaturated monomeric species for a period of time sufficient to allow the coating to form on the substrate, wherein the one or more unsaturated monomeric species comprise (i) an aromatic moiety and (ii) a carbonyl moiety.

8. The method of claim 7, wherein the one or more unsaturated monomeric species comprise a monomeric compound that is unsaturated and comprises (i) an aromatic moiety and (ii) a carbonyl moiety.

9. The method of claim 7, wherein the monomer compound comprises a moiety A or B:

wherein each R is independently selected from hydrogen, optionally substituted branched or straight chain alkyl, or optionally substituted cycloalkyl.

10. The method of claim 8 or 9, wherein the monomer compound is a compound of formula (I):

Q-Z-Ar

(|)

wherein

Q is selected from the structures (Qa) and (Qb):

wherein R is¹、R²And R³Each of which is independently selected from hydrogen, optionally substituted branched or straight chain C₁-C₆Alkyl, or optionally substituted C₃-C₈A cycloalkyl group;

z is a direct bond or a linking moiety; and is

Ar is an optionally substituted aromatic moiety.

11. The method of claim 10, wherein R¹、R²And R³Each of which is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, tert,N-pentyl, neopentyl, n-hexyl, isohexyl and 3-methylpentyl.

12. The method of claim 11, wherein R¹、R²And R³Each of which is hydrogen.

13. The method of any one of claims 10 to 12, wherein the monomeric compound of formula (I) is a compound of formula (Ia):

14. the method of any one of claims 10-13, wherein Z has the formula:

-(CH₂)_n-

wherein n is an integer from 0 to 27.

15. The method of claim 14, wherein n is an integer from 0 to 2.

16. The method of claim 15, wherein n is 1.

17. The method of any one of claims 10-16, wherein Ar is an optionally substituted monocyclic aromatic moiety or an optionally substituted bicyclic aromatic moiety.

18. The method of claim 17, wherein Ar is optionally substituted C₃-C₁₂And (4) an aryl group.

19. The method of claim 18, wherein Ar is optionally substituted phenyl.

20. The method of any one of claims 8-19, wherein the monomer compound is benzyl acrylate.

21. The method of any one of claims 8-19, wherein the monomeric compound does not contain any fluorine atoms.

22. The method of claim 7, wherein the one or more unsaturated monomeric species comprises a crosslinking agent.

23. The method of any one of claims 8-21, wherein the one or more unsaturated monomeric species further comprises a crosslinking agent.

24. The method of claim 22 or claim 23, wherein the crosslinking reagent comprises (i) an aromatic moiety and (ii) a carbonyl moiety.

25. The method of any one of claims 22 to 24, wherein the crosslinking reagent is independently selected from compounds of formula (II) or (III):

wherein

Y¹、Y²、Y³、Y⁴、Y⁵、Y⁶、Y⁷And Y⁸Each independently selected from hydrogen, optionally substituted branched or straight chain C₁-C₆Alkyl, optionally substituted C₁-C₆Cycloalkyl and optionally substituted C₁-C₆An aryl group; and is

L is a linking moiety.

26. The method of claim 25, wherein group L has the formula:

wherein

Each Y⁹Independently selected from the group consisting of a bond, -O-C (O) -, -O-, -Y¹¹-O-C(O)-、-C(O)-O-Y¹¹-、-O-C(O)-Y¹¹-、-Y¹¹-C(O)-O-、-OY¹¹-and-Y¹¹O-in which Y¹¹Is optionally substituted branched, linear or cyclic C₁-C₈An alkylene group; and is

Y¹⁰Selected from optionally substituted branched, linear or cyclic C₁-C₈Alkylene groups, arylene groups, and siloxane groups.

27. The method of any one of claims 22 to 26, wherein the crosslinking agent is independently selected from divinyl adipate (DVA), 1, 4-butanediol divinyl ether (BDVE), 1, 4-cyclohexanedimethanol divinyl ether (CDDE), 1, 7-octadiene (17OD), 1,2, 4-Trivinylcyclohexane (TVCH), 1, 3-divinyltetramethyldisiloxane (DVTMDS), diallyl 1, 4-cyclohexanedicarboxylate (DCHD), tetraallyloxyethane (GBDA), and 1, 4-phenylene diacrylate.

28. The method of any one of claims 22-27, wherein the crosslinking reagent is divinyl adipate (DVA).

29. The method of any one of claims 22-27, wherein the crosslinking reagent does not contain any fluorine atoms.

30. A substrate provided with a polymeric nanocoating, wherein said coating is obtainable by the method according to any one of claims 7 to 29.

Technical Field

The present invention relates to coatings. In particular, the present invention relates to substrates bearing polymeric nanocoating, and methods for forming polymeric nanocoating on substrates, but is not limited thereto.

Background

In many cases, it may be advantageous to protect the substrate by applying a protective coating. For example, it may be desirable to protect the substrate from damage caused by moisture, dust, chemical agents, or extreme temperatures, particularly from contamination caused by liquids such as water.

It is known to apply protective coatings to substrates by wet chemical techniques such as brushing, spraying and dipping. The conformal coating takes on the 3D shape of the substrate on which it is formed and covers the entire surface of the substrate. For example, it is known to apply relatively thick protective coatings to electronic substrates based on parylene technology. Conformal coatings formed in this manner typically have a thickness of 30-130 μm for acrylic, epoxy or urethane resins and a thickness of 50-210 μm for silicone resins.

An alternative approach is to form water-repellent coatings using perfluoroalkyl chain monomers by a plasma polymerisation process (see for example WO 9858117). This technique allows the formation of relatively thin coatings whose water resistance is due to the presence of fluorocarbons.

However, the fluorocarbon used in these coatings can have adverse environmental effects. In addition, fluorocarbon chemical reactions produce HF as a byproduct of the coating deposition process, resulting in reduced process safety and increased cost of exhaust gas treatment.

There remains a need in the art for efficient protective coatings that do not suffer from the drawbacks of coatings applied in the prior art methods. Such coatings may also increase the resistance of the substrate to, for example, liquids, enhance durability, enable more efficient manufacture of protected substrates, and/or improve the environmental impact of the manufacturing process. It is an object of the present invention to provide a solution to this and/or at least one other problem associated with the prior art.

Disclosure of Invention

A first aspect of the invention provides a substrate bearing a polymeric nanocoating, wherein the coating comprises (i) aromatic moieties and (ii) carbonyl moieties.

A second aspect of the invention provides a method for forming a polymeric nanocoating on a substrate, the method comprising exposing the substrate to a plasma comprising one or more unsaturated monomeric species for a time sufficient to allow the coating to form on the substrate, wherein the one or more unsaturated monomeric species comprises (i) an aromatic moiety and (ii) a carbonyl moiety.

A third aspect of the invention provides a substrate provided with a polymeric nanocoating, wherein the coating is obtainable by the method according to the second aspect of the invention.

Drawings

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

fig. 1 shows an electrical test apparatus for determining the resistance of a coating.

Detailed Description

Aspects of the invention relate to a substrate with a polymeric nanocoating and a method for forming a polymeric nanocoating. The method for forming a nanocoating uses unsaturated monomeric species that include an aromatic moiety and a carbonyl moiety, and the nanocoating includes an aromatic moiety and a carbonyl moiety.

It has been found that the nanocoating provided by the present invention can provide desirable barrier properties and durability. Without wishing to be bound by theory, it is generally believed that: (i) the presence of aromatic moieties may give the coating a advantageously high density as well as relative chemical inertness and low polarity (and thus associated with enhanced barrier properties) due to the planar structure of these aromatic moieties; and (ii) the presence of carbonyl groups can help free radical polymerization and promote low energy polymerization, thereby avoiding fragmentation at higher energies that can degrade the quality of the barrier coating.

The presence of aromatic moieties and carbonyl moieties can be determined using methods well known in the art, such as FTIR/ATR. FTIR/ATR may, for example, indicate the presence of Ar-H and C ═ O fragments.

The coating is a polymer nanocoating. In general, the thickness of the nanocoating may be 15,000nm or less. Coatings of 15,000nm or less thickness can be prepared, for example, by using a plasma deposition process.

In one embodiment, the thickness of the coating is 10,000nm or less, or 1000nm or less. In one embodiment, the thickness of the coating is 1nm or more, or 50nm or more.

The thickness of the coating may be, for example, 1 to 15,000nm, or 50 to 10,000nm, optionally 50 to 8000nm, 100 to 5000nm, 250nm to 5000nm, or 250nm to 2000 nm.

In one embodiment, the thickness of the coating is 1nm, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 100nm, 250nm, 500nm, 750nm, 1000nm, 1100nm, 1200nm, 1300nm, 1400nm, 1500nm, 1600nm, 1700nm, 1800nm, 1900nm, 2000nm, 2100nm, 2200nm, 2300nm, 2400nm or 2500nm, and/or the thickness of the coating is at most 15000nm, 14000nm, 13000nm, 12000nm, 11000nm, 10000nm, 9000nm, 8000nm, 7000nm, 6000nm, 5500nm, 5000nm, 4900nm, 4800nm, 4700nm, 4600nm, 4500nm, 4400nm, 4300nm, 4200nm, 4100nm, 4000nm, 3900nm, 3800nm, 3600nm, 3500nm, 3400nm, 3300nm, 3200nm, 3000nm, 2700nm, 2100nm, 2000nm, 2100nm, or 2500 nm.

The thickness of the coating can be determined, for example, as set forth below, by spectral reflectometry, optionally using optical constants such as those verified by spectroscopic ellipsometry.

Preferably, the coating may be substantially free of fluorine. The absence of fluorine improves environmental characteristics and improves safety during the manufacturing process and potentially reduces the cost of exhaust gas treatment. In one embodiment, the coating is substantially free of halogens.

Preferably, the coating may be a protective layer, which for example prevents damage due to contact with water or other liquids.

In one embodiment, the coating may be a barrier coating that may function as a physical barrier, for example by providing a physical barrier to mass and/or electron transport. In one embodiment, the coating limits the diffusion of water, oxygen, and ions. In one embodiment, the coating provides electrical resistance.

In one embodiment, the coating is substantially free of pinholes. Preferably, Δ Z/d <0.15, where Δ Z is the change in average height over AFM line scan, expressed in nm, and d is the coating thickness, expressed in nm.

The value of az/d indicates the extent to which the defects/voids extend into the coating at the surface of the coating, i.e. the percentage value of the depth of the defects with respect to the total coating thickness. For example, Δ Z/d of 0.15 means that the voids on the surface extend only down to at most 15% of the coating thickness. Coatings with Δ Z/d <0.15 are defined herein as substantially pinhole free. If the gap is larger than this value, it is unlikely that the desired function is achieved.

The coating is preferably conformal, meaning that the coating takes on the 3D shape of the substrate and covers substantially the entire surface of the substrate. This is advantageous to ensure that the coating has a sufficient thickness to function optimally over the entire surface of the substrate. The meaning of the term "substantially covering the entire surface" will depend to some extent on the type of surface to be covered. For example, for some substrates, it may be desirable to completely cover the surface in order for the substrate to perform its function after, for example, immersion in water. However, for other components or housings, it may be permissible for there to be a small gap within the coverage area.

The substrate bearing or having a polymer nanocoating formed thereon may be, for example, an electronic device or a component thereof.

It is well known that electronic and electrical devices are extremely sensitive to damage caused by contamination of liquids, such as environmental liquids, particularly water. Contact with liquids during normal use or through accidental exposure can result in electrical shorts between electronic components and irreparably damage circuit boards, electronic chips, etc.

In one embodiment, the substrate is an electronic device or a component thereof. The electronic device may for example be selected from the group of: small portable electronic devices such as mobile phones, smart phones, pagers, radios, hearing aids, portable computers, laptops, tablets and Personal Digital Assistants (PDAs). These devices, when used externally or internally adjacent to a liquid, can be exposed to a significant amount of liquid contamination. Such devices are also prone to accidental exposure to liquids, for example when dropped into a liquid or splashed with a liquid.

In another embodiment, the electronic device may be selected from the group of: outdoor lighting systems, radio antennas, and other forms of communication equipment.

Throughout this specification, the term "aromatic moiety" encompasses the terms "aryl", "heteroaryl", "arylene" and "heteroaryl", unless expressly stated otherwise.

Typically, the aromatic moiety is an optionally substituted aromatic moiety.

In one embodiment, the optionally substituted aromatic moiety is an optionally substituted monocyclic aromatic moiety or an optionally substituted bicyclic aromatic moiety. The optionally substituted aromatic moiety may, for example, contain 3 to 12 carbon atoms.

The optionally substituted aromatic moiety may be an aryl group, such as a monocyclic or bicyclic aryl group. The optionally substituted aromatic moiety may be C₃-C₁₂Aryl radical, C₅-C₁₂Aryl radical, C₅-C₁₀Aryl radical, C₅-C₈Aryl or C₅-C₆And (4) an aryl group.

In one embodiment, the optionally substituted aromatic moiety is free of heteroatoms. Preferably, the optionally substituted aromatic moiety is an optionally substituted phenyl. The phenyl group may be unsubstituted or substituted by one or more substituents; the substituents may for example be selected from one or more alkyl groups. The one or more alkyl groups may for example be selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, neopentyl, n-hexyl, isohexyl and 3-methylpentyl.

In another embodiment, the optionally substituted aromatic moiety contains a heteroatom. The optionally substituted aromatic moiety may be an optionally substituted heteroaryl, such as a monocyclic or bicyclic heteroaryl. Optionally substituted heteroaryl groups may contain 1 to 12 carbon atoms and one or more N, O or S atoms. Heteroaryl groups may be 5-or 6-membered rings containing one or more N atoms.

The optionally substituted aromatic moiety may be an arylene group, such as a monocyclic or bicyclic arylene group. The optionally substituted aromatic moiety may be C₃-C₁₂Arylene radical, C₅-C₁₂Arylene radical, C₅-C₁₀Arylene radical, C₅-C₈Arylene radicals or C₅-C₆An arylene group.

In one embodiment, the optionally substituted aromatic moiety is free of heteroatoms. Preferably, the optionally substituted aromatic moiety is an optionally substituted phenylene. The phenylene group may be unsubstituted or substituted with one or more substituents; the substituents may for example be selected from one or more alkyl groups. The one or more alkyl groups may for example be selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, neopentyl, n-hexyl, isohexyl and 3-methylpentyl.

In another embodiment, the optionally substituted aromatic moiety contains a heteroatom. The optionally substituted aromatic moiety may be an optionally substituted heteroarylene, such as a monocyclic or bicyclic heteroarylene. Optionally substituted heteroarylene groups may contain 1 to 12 carbon atoms and one or more N, O or S atoms. The heteroarylene group may be a 5-or 6-membered ring containing one or more N atoms.

Throughout this specification, unless explicitly stated otherwise:

the "optionally substituted" group may be unsubstituted or substituted by one or more, e.g. one or two, substituents. These substituents may be selected, for example, from alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, and heterocyclyl groups; carboxylic acid and carboxylate ions; a carboxylic acid ester; a carbamate; an alkoxy group; ketone groups and aldehyde groups; amine and amide groups; -OH; -CN; -NO₂(ii) a And a halogen.

Alkyl groups may be straight or branched chain alkyl groups. The alkyl group may be C₁To C₂₇Alkyl radical, C₁To C₂₀Alkyl radical, C₁To C₁₂Alkyl radical, C₁To C₁₀Alkyl radical, C₁To C₈Alkyl radical, C₁To C₆Alkyl radical, C₁To C₅Alkyl radical, C₁To C₄Alkyl radical, C₁To C₃Alkyl, or C₁To C₂An alkyl group. The alkyl group may be chosen, for example, from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butylAlkyl, n-pentyl, neopentyl, n-hexyl, isohexyl and 3-methylpentyl.

Cycloalkyl may be C₃To C₈Cycloalkyl radical, C₃To C₇Cycloalkyl radical, C₃To C₆Cycloalkyl radical, C₄To C₆Cycloalkyl, or C₅To C₆A cycloalkyl group.

The alkylene group may be a linear or branched alkylene group. The alkylene group may be C₁To C₂₇Alkylene radical, C₁To C₂₀Alkylene radical, C₁To C₁₂Alkylene radical, C₁To C₁₀Alkylene radical, C₁To C₈Alkylene radical, C₁To C₆Alkylene radical, C₁To C₅Alkylene radical, C₁To C₄Alkylene radical, C₁To C₃Alkylene, or C₁To C₂An alkylene group.

The halogen group can be fluorine (F), chlorine (Cl), bromine (Br) or iodine (I); preferably fluorine (F).

The one or more monomeric species are unsaturated.

The use of unsaturated monomer species allows the use of lower activation energies than are required for saturated monomer species. This helps to avoid fragmentation of the monomer species during the plasma process, thereby achieving better structure retention and improved barrier coating quality.

The one or more unsaturated monomer species may comprise a monomer compound that is unsaturated and comprises (i) an aromatic moiety and (ii) a carbonyl moiety.

The aromatic moiety may be an optionally substituted aromatic moiety as defined above.

In one embodiment, the monomer compound comprises a moiety a or B:

wherein each R is independently selected from hydrogen, halogen, optionally substituted branched or straight chain alkyl (e.g. C)₁-C₆Alkyl radical) Or optionally substituted cycloalkyl (e.g. C)₃-C₈Cycloalkyl groups).

In these embodiments, the carbonyl moiety (ii) forms part of either moiety a or B.

The functional groups in the moieties a and B may include, for example, acrylate moieties or vinyl ester moieties, which may stabilize the free radicals during polymerization.

Suitably, the monomer compound may comprise (i) an aromatic moiety linked to (ii) a moiety capable of facilitating free radical polymerisation, the moiety comprising a carbonyl moiety. The moiety capable of facilitating free radical polymerization also promotes low energy polymerization. The moiety capable of facilitating free radical polymerization may be attached to the aromatic moiety directly or through a linking moiety. Preferably, the moiety capable of facilitating free radical polymerization is moiety a or B as defined above.

Preferably, the monomeric compound is a compound of formula (I):

Q-Z-Ar

(|)

wherein

Q is selected from the structures (Qa) and (Qb):

wherein R is¹、R²And R³Each independently selected from hydrogen, optionally substituted branched or straight chain C₁-C₆Alkyl, or optionally substituted C₃-C₈A cycloalkyl group;

z is a direct bond or a linking moiety; and is

Ar is an optionally substituted aromatic moiety.

In one embodiment, R¹、R²And R³Each independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, neopentyl, n-hexyl, isohexyl and 3-methylpentyl. In one embodiment, R¹、R²And R³Each independently selected from hydrogen, methyl and ethyl. At one isIn the examples, R¹、R²And R³Each independently selected from hydrogen or methyl.

In one embodiment, R¹And R²Are all hydrogen. In one embodiment, R¹And R³Are all hydrogen. In one embodiment, R²And R³Are all hydrogen. In one embodiment, R¹、R²And R³Each of which is hydrogen.

In one embodiment, Q is a structure (Qa) as defined above. In one embodiment, Q is a structure (Qb) as defined above.

When Q is structure (Qa), the monomeric compound is a compound of formula (Ia):

wherein R is¹、R²、R³Z and Ar are as defined above.

In one embodiment, the compound of formula (Ia) is selected from the group consisting of benzyl acrylate, phenyl acrylate, and 2-phenylethyl acrylate. Preferably, the compound of formula (Ia) is benzyl acrylate.

When Q is structure (Qb), the monomeric compound is a compound of formula (Ib):

wherein R is¹、R²、R³Z and Ar are as defined above.

In formulae (I), (Ia) and (Ib), Ar represents an optionally substituted aromatic moiety. The optionally substituted aromatic moiety may be as defined above.

In formulae (I), (Ia) and (Ib), Z represents a direct bond or a linking moiety.

In one embodiment, Z is a direct bond.

In one embodiment, Z is a linking moiety. Suitably, Z may be an optionally substituted alkylene group, such as C₁-C₂₇Alkylene, which radical is unsubstituted or substituted by one or more substituents, which may be chosen, for example, from hydroxy, C₁-C₁₂Alkoxy radical, C₁-C₁₂Alkyl, hydroxy-C₁-C₁₂Alkyl and halogen. In one embodiment, one to ten carbon atoms in the alkylene chain are replaced by a spacer moiety selected from C₂-C₆Alkenylene, -O-, -S-and-NR '-, wherein R' is selected from hydrogen, optionally substituted branched or straight chain C₁-C₆Alkyl, or optionally substituted C₃-C₈A cycloalkyl group. In one embodiment, the alkylene group comprises 1,2, 3, 4, or 5 spacer moieties. In one embodiment, the alkylene group contains 1 to 3 spacer moieties. In one embodiment, the alkylene group contains 1 or 2 spacer moieties.

In one embodiment, the alkylene group is C₁-C₂₀An alkylene group. In one embodiment, the alkylene group is C₁-C₁₀Alkylene radicals, e.g. C₁-C₆An alkylene group. In one embodiment, the alkylene group is a linear alkylene group.

In one embodiment, the alkylene group is substituted with one or more substituents. In one embodiment, the alkylene group is unsubstituted.

In one embodiment, Z has the formula:

-(CH₂)_n-

wherein n is an integer from 0 to 27.

When n is 0, Z is a direct bond. When n is 1 or higher, Z is a linking moiety.

In one embodiment, the lower value of the possible range for n is 0, 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or 26, and/or the upper value of the possible range for n is 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, or 2. In one embodiment, n is an integer from 0 to 2, or n is 1 or 2. Preferably, n is 1.

In formulae (I), (Ia) and (Ib), Ar is an optionally substituted aromatic moiety. The optionally substituted aromatic moiety is as defined above.

In a preferred embodiment, the monomeric compound does not contain any fluorine atoms. Optionally, the monomeric compound does not contain any halogen atoms.

The one or more unsaturated monomer species may comprise a crosslinking agent.

Optionally, the one or more unsaturated monomer species may comprise a crosslinking agent in addition to the monomer compound as defined above.

In one embodiment, the one or more unsaturated monomer species comprise a monomer compound as defined above and optionally comprise a crosslinking agent.

In one embodiment, the crosslinking reagent comprises (i) an aromatic moiety and (ii) a carbonyl moiety.

In general, the crosslinking reagent may comprise two or more unsaturated bonds connected by means of one or more linking moieties.

In one embodiment, the crosslinking agent has a boiling point of less than 500 ℃ at standard pressure.

In one embodiment, the crosslinking agent is independently selected from compounds of formula (II) or (III):

wherein

Y¹、Y²、Y³、Y⁴、Y⁵、Y⁶、Y⁷And Y⁸Each independently selected from hydrogen, optionally substituted branched or straight chain C₁-C₆Alkyl, optionally substituted C₁-C₆Cycloalkyl and optionally substituted C₁-C₆An aryl group; and is

L is a linking moiety.

In one embodiment, L contains an aromatic moiety and a carbonyl moiety.

In one embodiment, L has the formula:

wherein

Each Y⁹Independently selected from the group consisting of a bond, -O-C (O) -, -O-, -Y¹¹-O-C(O)-、-C(O)-O-Y¹¹-、-O-C(O)-Y¹¹-、-Y¹¹-C(O)-O-、-OY¹¹-and-Y¹¹O-in which Y¹¹Is optionally substituted branched, linear or cyclic C₁-C₈An alkylene group; and is

Y¹⁰Selected from optionally substituted branched, linear or cyclic C₁-C₈Alkylene groups, arylene groups, and siloxane groups.

In one embodiment, each Y⁹Is a bond.

In one embodiment, each Y⁹is-O-.

In one embodiment, each Y⁹Is a vinyl ester or vinyl ether group.

In one embodiment, Y¹⁰Having the formula:

wherein each Y is¹²And Y¹³Independently selected from hydrogen, halogen, optionally substituted cyclic, branched or linear C₁-C₈Alkyl, or-OY¹⁴Wherein Y is¹⁴Selected from optionally substituted branched or straight chain C₁-C₈Alkyl or alkenyl, and

n "is an integer from 1 to 10.

In one embodiment, each Y¹²Is hydrogen and each Y¹³Is hydrogen, whereby Y¹⁰Is a linear alkylene chain. In this embodiment, Y⁹May for example be vinyl ester or vinyl ether groups.

In one embodiment, each Y¹²Is fluorine and each Y¹³Is fluorine, whereby Y¹⁰Is a linear perfluoroalkylene chain.

n "is an integer from 0 to 10. In one embodiment, the lower value of the possible range for n "is 0, 1,2, 3, 4, 5, 6, 7, 8, or 9, and/or the upper value of the possible range for n" is 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1. In one embodiment, n "is 4 to 6.

In one embodiment, Y¹⁰Having the formula:

wherein each Y is¹⁵Independently selected from optionally substituted branched or straight chain C₁-C₆An alkyl group.

In one embodiment, each Y¹⁵Is methyl. In one embodiment, each Y⁹Is a bond.

In one embodiment, Y¹⁰Having the formula:

wherein Y is¹⁶、Y¹⁷、Y¹⁸And Y¹⁹Each independently selected from hydrogen and optionally substituted branched or straight chain C₁-C₈An alkyl or alkenyl group. In one embodiment, the alkenyl group is vinyl.

In one embodiment, Y¹⁸Is hydrogen or vinyl, and Y¹⁶、Y¹⁷And Y¹⁹Each is hydrogen. In one embodiment, Y¹⁶、Y¹⁷、Y¹⁸And Y¹⁹Each of which is hydrogen. In another embodiment, Y¹⁸Is vinyl, and Y¹⁶、Y¹⁷And Y¹⁹Each is hydrogen.

In one embodiment, the group L has one of the following structures:

in one embodiment, the group L has one of the following structures:

for L, Y according to structure (e)¹⁰May for example be an alkylene chain or cycloalkylene group such as those shown in structures (b) and (d) above. The alkylene chain may for example be a linear alkylene chain.

When Y is¹⁰When it is cycloalkylene, it may be, for example, cyclohexylene, such as 1, 4-cyclohexylene.

For L, Y according to structure (f)¹⁰May for example be of structure (b), such as an alkylene chain; or is structure (d1) or structure (d 2).

For L, Y according to structure (g)¹⁰Can be, for example, a cycloalkylene group, such as a cyclohexylene group according to structure (d 1).

For L, Y according to structure (h)¹⁰May for example be structure (b).

For L, Y according to structure (i) or structure (j)¹⁰May for example be alkylene or cycloalkylene. Optionally, the alkylene or cycloalkylene group may be substituted with one or more vinyl or alkenyl ether groups, such as one or more vinyl ether groups.

When each Y is⁹When is a bond, each Y¹⁰For example, the structure may be any of the structures (b), (c), (d1) and (d 2).

In one embodiment, Y¹⁰Is a linear alkylene group, whereby the crosslinking agent is a diene, such as heptadiene, octadiene or nonadiene; in one embodiment, the crosslinking agent is 1, 7-octadiene.

When each Y is⁹When is O, each Y¹⁰May be, for example, branched or straight C₁-C₆Alkylene, preferably straight chain alkylene, most preferably C₄A linear alkylene group. In one embodiment, the crosslinking agent is 1, 4-butanediol divinyl ether.

It is understood that each Y⁹The radical may be bonded to any other Y⁹Group and Y¹⁰The groups combine to form a crosslinking agent.

The skilled artisan will appreciate that the above-mentioned cyclic, branched or straight chain C₁-C₈Possible substituents for each of the alkylene groups. The alkylene group may be substituted at one or more positions with a suitable chemical group. Each C₁-C₈Alkylene may be, for example, C₁-C₃、C₂-C₆Or C₆-C₈An alkylene group.

In one embodiment, the crosslinking reagent has alkyl chains Y on either side¹⁰And vinyl ester or vinyl ether groups.

In a preferred embodiment, the crosslinking reagent does not contain any fluorine atoms. Optionally, the monomeric compound does not contain any halogen atoms.

In one embodiment, the crosslinking agent is independently selected from divinyl adipate (DVA), 1, 4-butanediol divinyl ether (BDVE), 1, 4-cyclohexanedimethanol divinyl ether (CDDE), 1, 7-octadiene (17OD), 1,2, 4-Trivinylcyclohexane (TVCH), 1, 3-divinyltetramethyldisiloxane (DVTMDS), diallyl 1, 4-cyclohexanedicarboxylate (DCHD), tetraallyloxyethane (GBDA), and 1, 4-phenylene diacrylate.

In one embodiment, the crosslinking agent is divinyl adipate (DVA).

In one embodiment, the crosslinking reagent is 1, 4-butanediol divinyl ether (BDVE).

In one embodiment, for the compound of formula (III), the group L may be selected, for example, from branched or linear C₁-C₈Alkylene groups or ether groups. L may be, for example, C₃、C₄、C₅Or C₆Alkylene, preferably straight chain alkylene.

The chemical structure of the crosslinking reagent is set forth in table 1 below.

Table 1: crosslinking agent

Generally, in a plasma deposition process, an article to be treated is placed in a plasma deposition chamber, a glow discharge is ignited within the chamber, and a suitable voltage, which may be continuous wave or pulsed, is applied. The glow discharge is suitably ignited by applying a high frequency voltage, for example a voltage of 13.56 MHz.

The monomer species may each be in the form of a gas, liquid, or solid (e.g., powder) at room temperature prior to entering the deposition chamber. Preferably, however, the one or more monomeric species are liquid at room temperature, which may include monomeric compounds and/or crosslinking agents.

In one embodiment, the one or more monomer species, which may include a monomer compound and/or a crosslinking agent, are introduced into the plasma deposition chamber in a liquid phase.

When both the monomer compound and the crosslinking agent are present, the crosslinking agent is miscible with the monomer compound. They may be introduced into the plasma chamber together or separately. Alternatively, the crosslinking reagent is immiscible with the monomer compound and is introduced separately into the plasma chamber. In this case, the term "miscible" means that the crosslinking agents are soluble in the monomer compound and, when mixed, they form a solution of a uniform composition. The term "immiscible" is used to indicate that the crosslinking agent is only partially soluble or insoluble in the monomer compound and thus forms an emulsion or separates into two layers.

The one or more monomer species will suitably be present in the plasma in a gaseous state. The plasma may contain only the vapor of the monomer species. Such vapors may be formed in situ, and the monomer species introduced into the chamber in liquid form. The monomer species may also be combined with a carrier gas, particularly an inert gas such as helium or argon.

In a preferred embodiment, the one or more monomeric species may be delivered into the chamber by means of an aerosol device, such as a nebulizer, or the like, as described in, for example, WO 2003/097245 and WO 2003/101621. In such an arrangement, a carrier gas may not be required, which may advantageously help achieve high flow rates.

The exact flow rate of the one or more monomer species into the chamber may depend to some extent on the nature of the particular monomer species used, the nature of the substrate, the desired coating characteristics, and the volume of the plasma chamber. In some embodiments of the invention, the one or more monomer species are introduced into the chamber at a gas flow rate of at least 1sccm (standard cubic centimeter per minute) and preferably in the range of 1 to 2500 sccm. In one embodiment, the one or more monomer species introduced into the chamber has a gas flow rate of 1sccm, 5sccm, 10sccm, 15sccm, 20sccm, 25sccm, 30sccm, 35sccm, 40sccm, 45sccm, 50sccm, 100sccm, 150sccm, 200sccm, or 250sccm, and/or up to 2500sccm, 2000sccm, 1500sccm, 1000sccm, 750sccm, 500sccm, 250sccm, 200sccm, 100sccm, or 60 sccm.

The gas flow rate of the monomer species may be calculated from the liquid monomer flow rate, for example by using the ideal gas law, i.e. assuming that the monomer species in the chamber acts in a similar manner to an ideal gas, in this case, one mole of gas occupies 22400cm at 273K and 1 atmosphere (STP)³The volume of (a).

The step of exposing the substrate to the plasma may comprise a Pulsed (PW) deposition step. Alternatively or additionally, the step of exposing the substrate to the plasma may comprise a Continuous Wave (CW) deposition step.

The term pulse may mean that the plasma cycles between a state in which no (or substantially no) plasma is emitted (off-state) and a state in which a specific amount of plasma is emitted (on-state). Alternatively, pulsing may mean that there is continuous plasma emission, but the amount of plasma cycles between an upper limit (on state) and a lower limit (off state).

For pulsed plasmas, higher average powers can be achieved by using higher peak powers and varying the pulsing scheme (i.e., on-time/off-time).

Optionally, the voltage is pulsed in a sequence wherein the ratio of on time/off time is in the range of 0.001 to 1, optionally in the range of 0.002 to 0.5. For example, the on-time may be 10-500 μ s, or 35-45 μ s, or 30-40 μ s, such as about 36 μ s; and the off-time may be 0.1 to 30ms, or 0.1 to 20ms, or 5 to 15ms, for example 6 ms. The on-time may be 35, 40, 45 mus. The off-time may be 0.1, 1,2, 3, 6, 8, 10, 15, 20, 25, or 30 ms.

Optionally, the voltage is applied in a pulsed field for a time period of 30 seconds to 90 minutes. Optionally, the voltage is applied in a pulsed field for 5 to 60 minutes.

The RF power supplied may be 1 to 2000W, for example 50 to 1000W, 100 to 500W, 125 to 250W.

The peak power may be 1 to 2000W, for example 50 to 1000W, 100 to 500W, 125 to 250W or about 160W. In one embodiment, the peak power is 1W, 50W, 100W, 125W, 150W, 200W, 300W, 400W or 500W, and/or is at most 10kW, 5000W, 4000W, 3000W, 2000W, 1000W, 900W, 800W, 700W, 600W, 500W, 400W, 300W, 250W or 200W.

For continuous wave plasma or pulsed plasma, the ratio of peak power to monomer flow may be 2 to 60W/sccm, 2 to 40W/sccm, 2 to 25W/sccm, or 5 to 20W/sccm. In one embodiment, the ratio of the peak power to the monomer flow is 0.1W/sccm, 0.5W/sccm, 0.6W/sccm, 0.7W/sccm, 0.8W/sccm, 0.9W/sccm, 1W/sccm, 2W/sccm, 3W/sccm, 4W/sccm, or 5W/sccm, and/or at most 40W/sccm, 39W/sccm, 38W/sccm, 35W/sccm, 30W/sccm, 25W/sccm, 20W/sccm, 15W/sccm, 10W/sccm, 9W/sccm, 8W/sccm, 7W/sccm, 6W/sccm, 5W/sccm, 4W/sccm, 3W/sccm, or 2W/sccm.

The peak power density of the plasma may be 0.001 to 40W/L, or at least 2W/L, or about 20W/L during exposure of the substrate to the continuous wave plasma or the pulsed plasma. In one embodiment, the peak power density is 0.001W/L, 0.01W/L, 0.1W/L, 0.2W/L, 0.3W/L, 0.4W/L, 0.5W/L, 0.6W/L, 0.7W/L, 0.8W/L, 0.9W/L, 1W/L, 2W/L, 3W/L, 4W/L, 5W/L, 10W/L, 15W/L, or 20W/L, and/or is at most 25W/L, 20W/L, 15W/L, 10W/L, 5W/L, 4W/L, 3W/L, or 2W/L.

When both a monomer compound and a crosslinking agent are present, in one embodiment, the volume ratio of the crosslinking agent to the monomer compound is 0.1:99.9 to 90:10, or 1:99 to 50:50, or 1:99 to 30: 70. In one embodiment, the volume ratio of the crosslinking reagent to the monomer compound is 1:99 to 25:75, 1:99 to 20:80, 5:95 to 20:80, or 5:95 to 15: 85. In one embodiment, the volume ratio of the crosslinking reagent to the monomer compound is about 10: 90.

In one embodiment, the volume ratio of the crosslinking reagent to the monomer compound is 0.1:99.9, 1:99, 2:98, 3:97, 4:96, 5:95, 6:96, 7:93, 8:92, 9:91, or 10:90, and/or the volume ratio of the crosslinking reagent to the monomer compound is at most 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 29:71, 28:72, 27:73, 26:74, 25:75, 24:76, 23:77, 22:78, 21:79, 20:80, 19:81, 18:82, 17:83, 16:84, 15:85, 14:86, 13:87, 12:88, 11:89, or 10: 90.

As is known to the skilled person, volume ratio measurements are often used in the field of plasma deposition when introducing reagents into the plasma deposition chamber. Alternatively, the ratio between reagents such as monomer compounds and crosslinking reagents may be expressed in terms of the molar ratio of reagents introduced into the chamber. This is called the input molar flow ratio.

In one embodiment, the monomer compound and the crosslinking reagent are optionally introduced into the plasma deposition chamber in a liquid phase, and the input molar flow ratio of the crosslinking reagent to the monomer compound is 1:20 to 10:1, or 1:20 to 1: 1. In one embodiment, the input molar flow ratio of the crosslinking reagent to the monomer compound is 1:20 to 1:2, 1:15 to 1:5, 1:14 to 1:6, or 1:20 to 1: 6.

In one embodiment, the input molar flow ratio of the crosslinking reagent to the monomer compound is 1:20, 1:19, 1:18, 1:17, 1:16, 1:15, 1:14, 1:13, 1:12, 1:11, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, or 1:2, and/or the possible range of input molar flow ratio of the crosslinking reagent to the monomer compound is at most 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, or 1: 19.

For a particular monomer compound and crosslinking reagent, the volume ratio of crosslinking reagent to monomer compound can be readily converted to a molar ratio of the crosslinking reagent to the monomer compound, and vice versa.

For example, when the crosslinking reagent and the monomer compound are introduced into the plasma deposition chamber in the liquid phase and the volume ratio of the crosslinking reagent to the monomer compound is 10:90, if the crosslinking reagent is DVA and the monomer compound is benzyl acrylate, the input molar flow ratio of DVA to benzyl acrylate is about 1: 8.

Throughout the detailed description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" means "including but not limited to" and does not exclude other components, features or steps. In addition, unless the context dictates otherwise, the singular encompasses the plural: in particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context dictates otherwise.

Preferred features of each aspect of the invention may be described in connection with any other aspect. Within the scope of the present application, it is expressly intended that various aspects, embodiments, examples and alternatives set forth in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular individual features thereof, may be presented independently or in any combination. That is, features of all embodiments and/or any embodiment may be combined in any manner and/or combination unless such features are incompatible.

Examples of the invention

Plasma deposition process

For experiments performed in a 22L plasma chamber, plasma polymerization experiments were performed in a metal reaction chamber with a working volume of 22 liters. The chamber consists of a two-part, vertically oriented, shallow rectangular parallelepiped cavity with a single open face that is sealed in a solid metal door by a Viton O-ring on the outer rim. All surfaces were heated to 37 ℃. Inside the chamber is a single perforated metal electrode, the area of which follows the open face of the cavity, also oriented vertically and attached to the corners of a metal door by connectors through the center of which the RF power unit is fed. For pulsed plasma deposition, the RF power unit is controlled by a pulse generator.

The backside of the chamber was connected to a metal pump line, a pressure control valve, a compressed dry air supply, and a vacuum pump through a larger cavity with a total volume of 125L. The chamber door contains several cylindrical ports for connection to pressure gauges, monomer delivery valves, temperature controls, and gas feed lines, which in turn are connected to mass flow controllers.

In each experiment, the sample was placed vertically on a nylon staple attached to the perforated electrode, facing the door.

The reactor is evacuated to base pressure (typically<10 mtorr). The process gas is delivered to the chamber using a mass flow controller, with a typical gas flow value between 2-25 sccm. Monomer is delivered into the chamber with a typical monomer gas flow rate value of between 5-100 sccm. The pressure inside the reactor was maintained between 20-30 mtorr. Plasma was created using a 13.56MHz RF. The process typically contains at least Continuous Wave (CW) plasma and Pulsed Wave (PW) plasma steps. Optionally, these steps may be performed by an initial activation step using a Continuous Wave (CW) plasma. Activation of the CW plasma (if used) took 1 minute, the CW plasma took 1 or 4 minutes, and the time of the PW plasma varied from experiment to experiment. In each case, the peak power setting was 160W, and the pulse condition was the on-time (t)_on) 37 mus and off-time (t)_off) 10 ms. At the end of the deposition, the RF power was turned off, the monomer delivery valve was closed and the chamber was pumped to base pressure. The chamber was vented to atmospheric pressure and the coated sample was removed.

In each experiment, a test Printed Circuit Board (PCB) and accompanying Si wafer were used. The Si wafer allows measurement of physical properties of the formed coating, such as XRR for surface morphology AFM and for coating density. The metal tracks of the test PCB were gold coated copper. A Si wafer is placed on the top front side of the PCB.

Analytical method

The following methods were used to investigate various properties of exemplary polymeric nanocoatings according to the present invention.

Resistance in tap water

The test method is designed to evaluate the ability of different coatings to provide electrical barriers on printed circuit boards and predict the ability of smartphones to pass IEC 6052914.2.7 (IPX7) tests. The method is designed for tap water. The present test involves measuring the current-voltage (IV) characteristics of a standardized Printed Circuit Board (PCB) in water. The PCB was designed with 0.5mm spacing between the electrodes to allow evaluation of the time for cross-track electrochemical migration to occur in water. The degree of electrochemical activity is quantified by measuring the current; lower current indicates good coating quality. This method has proven to be extremely effective in distinguishing between different coatings. The properties of the coating can be quantified, for example, in terms of resistance at 4V and 8V and 21V. The resistance measured on the untreated test device was about 100 ohms when 16V/mm was applied.

The coated PCB to be tested was placed in a beaker containing water and connected to an electrical test apparatus as shown in fig. 1. The plate is centered in the beaker both horizontally and vertically to minimize the effect of local ion concentration (the vertical position of the plate is of paramount importance; the horizontal plane should reach the blue line). When the PCB is connected, the power supply is set to the desired voltage and the current is immediately monitored. The applied voltage is, for example, 8V and the PCB is held at the set voltage for 13 minutes while the current is continuously monitored during this time period.

The resulting coating was tested. It has been found that when the resistance value of the coating is above 1MOhm, the coated device will successfully pass the IPX7 test. The nature of the device being coated (e.g., the type of smartphone) will affect the testing (e.g., due to changes in materials, access points, power consumption, etc.).

Resistance in salt water

The test method is consistent with the method described above with respect to "resistance in tap water", however, brine is used instead of tap water. The composition of the brine was 5% w/v NaCl, i.e. 5 g NaCl per 100ml water.

Extended electrical testing

Following the same method as the tap water resistance test (see above), the samples were immersed in tap water under an applied voltage for a longer duration.

Salt spray test

The samples were placed in a chamber and exposed to a 5% salt spray for 2 hours. Subsequently, it was exposed to high humidity (95% RH, 50 ℃) for 22 hours. This cycle was performed three times, and the samples were then subjected to a tap water resistance test (see above).

Contact force

The sample was pressed with a probe to measure the force required to penetrate the coating and contact the metal underneath the coating.

Treatment of

The sample was placed on a balance and pressed vertically with a thumb for 30 seconds at a weight of 150g, performed 5 or 10 times. After thumb press, the samples were subjected to corrosion testing, in which a drop of water was placed on the treated portion and the plate was subjected to a continuous voltage (8V) for 30 seconds. Pass criteria are no bubbles or significant corrosion.

Solvent resistance test

Solvent resistance tests were performed in acetone, isopropanol and hexadecane for 10 minutes, 30 minutes and 2 hours. The tape plate samples were vertically immersed in beakers containing acetone, isopropanol, and hexadecane, approximately to the midpoint of the plate, held for 10 minutes, 30 minutes, and 2 hours, and a tap water resistance test was performed between each solvent immersion (see above).

Adhesion of coatings to substrates

Two tests were designed to monitor the adhesion of the coating to the substrate under high temperature induced stress, which is consistent with the type of exposure seen during the assembly process of the processed PCB in the factory.

(1) Thermal delamination temperature

The test setup contained a microscope for observing the coating changes, a digital thermometer, a heating plate, a sample holder and a camera (test recorder for determining the results). During testing, the treated PCB was heated from room temperature to 125 ℃ or higher by a hot plate and the increase in temperature was recorded with a digital thermometer. The quantitative measurement used to compare the different coatings is the delamination temperature at which the first sign (bubble) of the film lifting from the substrate can be observed.

(2) Resistance in tap water after 5 minutes at 135 ℃

The sample was placed in an oven at 135 ℃ for 5 minutes. After removal of the sample, the sample was visually inspected for any delamination, followed by a tap water resistance test (see above).

These tests can be combined with the surface insulation resistance test described above (e.g., resistance in tap water) to determine if the coating barrier properties are retained after a thermal challenge.

Thickness of coating

The thickness of the coating formed was measured using a spectroscopic reflectometry apparatus (filmmetrics F20-UV) using optical constants verified by spectroscopic ellipsometry.

Spectroscopic ellipsometry

Spectroscopic ellipsometry is a technique for measuring the change in polarization between incident polarized light and light after interaction of the same (i.e., reflected light, transmitted light, etc.). The change in polarization is quantified by the amplitude ratio Ψ and the phase difference Δ. This variation is measured over a range of wavelengths using a broadband light source, and the normalized values of Ψ and Δ are measured as a function of wavelength. The ITAC MNT ellipsometer is an AutoSE from Horiba Yvon with a wavelength range of 450 to 850 nm. Many optical constants can be derived from Ψ and Δ values, such as film thickness and refractive index.

The data collected from the sample measurements includes the intensities of harmonics of the reflected or emitted signal within a predefined spectral range. These data are mathematically processed to obtain intensity values, referred to as Is and Ic, denoted by f (i).Starting from Ic and Is, the software calculates Ψ and Δ. In order to obtain the parameters of interest, such as thickness or optical constants, a model must be built to allow theoretical calculations of Ψ and Δ. By comparing theoretical data files with experimental data files to obtain the best fit (MSE or X)²) Thereby determining the parameter of interest. The best fit of the thin layer should result in X²<3, this value can be as large as 15 for thicker coatings. The model used was a three-layer Laurentz model comprising PTFE on a Si substrate finished with a mixed layer (PTFE + voids) to account for surface roughness.

Spectral reflectance measurement method

The thickness of the coating was measured using a Filmetrics F20-UV spectral reflectance measuring device. The instrument (F20-UV) measures the properties of the coating by reflecting light off the coating and analyzing the resulting reflection spectrum over a range of wavelengths. Depending on the wavelength of the incident light and the thickness and refractive index of the coating, the light reflected from different interfaces of the coating may be in-phase or out-of-phase, such that these reflections increase or decrease. This causes intensity oscillations in the reflection spectrum, which are characteristic of the coating.

To determine the thickness of the coating, filmetics software calculates a theoretical reflectance spectrum that matches the measured spectrum as closely as possible. The spectrum starts with an initial guess as to what the reflection spectrum should be based on a nominal coating stack (layered structure). This includes information about the thickness (accuracy 0.2nm) and refractive index (refractive index values can be obtained by spectroscopic ellipsometry) of the different layers and substrates that make up the sample. The theoretical reflectance spectrum is then adjusted by adjusting the properties of the coating until a best fit to the measured spectrum is found.

Alternative techniques for measuring thickness are probe profilometry and coating cross-section by SEM.

Monomer compound

The monomer compound used in these examples was benzyl acrylate having the formula (Cat. No. 2495-35-4):

crosslinking agent

The crosslinking reagent used in these examples was divinyl adipate (DVA) having the formula (Cat. No. 4074-90-2):

example 1

The plasma deposited coating was prepared as follows: the 9:1(v/v) benzyl acrylate/divinyl adipate monomer was prepared by mixing the two components in the specified ratio in a bottle. A Printed Circuit Board (PCB) was loaded into a 22L plasma chamber and the chamber was pumped to a vacuum of about 10 millitorr. Monomers were added to the 22L plasma chamber by a two-step process, using continuous wave and pulsed wave RF delivery.

The continuous wave step involved feeding monomer prior to RF ignition for a period of 70 seconds (40 seconds monomer only/30 seconds RF only). The process parameters for each operation were as follows:

monomer gas flow rate: 23sccm

Power: 250W

Setting pressure: 25 mTorr

The pulse wave period involved the delivery of monomer at a power to flow ratio of 0.28W/. mu.l/min over a period of 200 seconds (for a 500nm coating).

Monomer gas flow rate: 100sccm

Power: 160W

Setting pressure: 30 mTorr

Pulse on time: 37 mus; pulse off-time: 10ms

After deposition, the chamber is evacuated and vented to atmosphere.

The coating can meet the barrier performance standard under the thickness of 500nm when being deposited on a PCB, and the resistance in tap water is more than or equal to 1MOhm (applied voltage is 16V/mm). The barrier properties were found to be highly reproducible.

The 500nm coating was tested for barrier properties using the analytical method described above and the results are shown in table 2.

Examples 2 to 5

Table 2: plasma deposited coatings

A series of experiments were performed in 22L and 400L plasma chambers according to the same principle as example 1.

The results are presented in table 2.