A film-forming composition and its use

Abstract

The application provides a film-forming composition and application thereof, which comprises components A-C: A, a hydrophobic polymer I, which is a solid polymer; B, a hydrophobic polymer II, which is a film-forming polymer; and C, an organic solvent. The film-forming composition has good hydrophobicity and corrosion resistance, and is suitable for protection of electronic components such as circuit boards, especially for protection of circuit boards with connectors, and can form a protective coating on the surface of the circuit board and its components such as connectors, thereby protecting the connectors and other devices on the circuit board and the entire circuit board, without affecting the electrical connection of the connectors on the circuit board with other connectors, and can improve the thickness of the waterproof coating formed at the corner position of the circuit board components, thereby avoiding the problems of thin hydrophobic coating at the corner position of the circuit board components and easy corrosion and short-circuit failure caused thereby.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic component packaging materials, in particular to a film-forming composition and its application. BACKGROUND

[0002] Electronic devices contain circuit boards inside, on which connectors, chips, chip resistors and capacitors, wing-shaped pin devices and other electronic components are assembled. For the overall protection structure design of electronic devices, it is usually impossible to completely prevent external liquids (such as water, rainwater, sweat, and living liquids) from entering the interior of the electronic device. For example, when the waterproof level is below IPX4, in the daily use scenario, external liquids may enter the interior of the electronic device through the openings on the device housing, the gaps between structural parts, or the parts that can be permeated by air, etc., and through the processes of diffusion and condensation, liquid droplets are formed inside the device, which may cause corrosion and short circuit of the electronic components in the circuit board assembly. For example, when there is a certain voltage difference between two adjacent pins of an electronic component, if there is a water droplet or water film between the two adjacent pins, a rapid short circuit failure may occur (usually within a few hours, due to low insulation resistance or excessive leakage current caused by rapid electrochemical migration corrosion), even if such rapid short circuit failure does not occur, the continuous presence of liquid droplets in the electronic device may also cause corrosion of the exposed metal on the electronic component, which may still cause failure of the electronic device. Therefore, it is necessary to provide a protective coating on the circuit board and the components therein to prevent water and other components from entering the interior of the electronic device and causing corrosion of the components inside the electronic device.

[0003] However, the existing circuit board protection materials generally have poor hydrophobicity, serious corner effect (which may cause the coating at the corner position to be too thin), and are not conducive to the electrical connection between the connectors on the circuit board and other connectors, which limits their application.

[0004] Specifically, the related art uses a conformal coating material (commonly known as a three-proofing paint) to strengthen the protection of the circuit board assembly, and the coating material used for the circuit board mainly uses a polyacrylate, silicone, polyurethane, alkyd resin, fluorine-containing material, etc. system, and can use spraying, brushing, dipping, etc. process to apply a conformal coating (usually a thin layer of insulating coating, generally about 15um-150um in thickness) on the circuit board assembly, which plays a protective role of moisture-proof, salt spray-proof, mildew-proof, etc. However, for the circuit board with connectors (such as BTB connectors, USB interfaces, radio frequency connectors, etc.), such conformal coating materials are not suitable, specifically, when the connector of the circuit board is assembled with another connector, the connecting terminals of the two connectors need to be connected together to make the two connectors electrically connected (electrically conductive), and when the conformal coating material is used to form an insulating coating on the surface of the connector of the circuit board, the insulating coating cannot be effectively pierced or pushed away by the connecting terminals of the two connectors, thereby affecting the electrical conductivity of the two connectors, especially in the process of equipment processing or use, the connector usually needs to be plugged in and out for many times, and the tolerance of the insulating coating existing on the cross section of the connecting contact is lower. Therefore, when the above-mentioned conformal coating material is used to protect the circuit board with connectors, when the coating material is applied on the single board, the connector usually needs to be shielded to avoid the surface of the connector contact being covered by the insulating coating formed by the coating material, thereby avoiding affecting the effective electrical connection between the connectors, but this will make the connector on the circuit board become the weak point of the electronic device, and after the external liquid enters the inside of the electronic device, short circuit and corrosion failure, etc. problems are prone to occur at the connector position on the circuit board.

[0005] The vacuum chemical vapor deposition method is used to deposit a nano-hydrophobic film (usually with a thickness of tens to hundreds of nanometers) on the surface of a substrate. In the process, the substrate surface is cleaned and activated by plasma discharge in a vacuum environment, and the energy for the chemical bond opening of the film deposition raw material molecules is provided to promote the continuous polymerization reaction. The substrate surface activated by plasma and the film deposition raw material monomers are combined by chemical bonds, and the monomers continuously polymerize and grow to form a nano-thickness organic molecular protective layer (nano-hydrophobic film) on the surface of the substrate to be coated. The process mainly includes the following steps: placing the whole machine to be processed into the cavity, vacuumizing, generating plasma gas, injecting reaction monomers with hydrophobic properties, depositing a nano-hydrophobic film on the surface of the whole machine, breaking the vacuum, and taking out the whole machine. The film deposition material is usually a fluorine-containing material with certain hydrophobic properties, usually a fluorocarbon compound. If a nano-hydrophobic film is deposited on the entire surface of a circuit board by the vacuum chemical vapor deposition method, the circuit board and the connectors and other devices on its surface can be protected to some extent. However, if the thickness of the nano-hydrophobic film is large, it is not conducive to being pierced by the connecting terminals of the connectors, which will affect the electrical connection of the connectors on the circuit board with other connectors. If the thickness of the nano-hydrophobic film is reduced so that it can be pierced by the connecting terminals of the connectors, the nano-hydrophobic film is too thin, and the protection effect on the circuit board is poor, which cannot meet the corrosion prevention requirements of the circuit board assembly in electronic equipment. In addition, the vacuum chemical vapor deposition method has the defects of complex process and high cost, which restricts its application in circuit board protection.

[0006] Therefore, the protective materials in the prior art generally have the problem of being not conducive to the electrical connection of the connectors on the circuit board with other connectors.

[0007] In addition, the devices on the circuit board usually have corner structures (such as the corner / angle positions of the device shell or 3D-shaped parts (such as 3D pins)), and the existing protective materials generally have a serious corner effect, which makes the protective film layer at the corner position too thin. Specifically, when the protective material is applied to the surface of the circuit board and the components on the circuit board, the uncured protective material has a large flowability, which causes the protective material at the corner position on the circuit board assembly to flow easily, resulting in a too-thin coating (protective film layer) formed at the corner position, which is prone to water failure and other problems, making it difficult for the circuit board to meet the reliable power-on requirements under the single-board component immersion and water test scenarios.

[0008] In addition, the water contact angle of the coating formed by the existing protective material is usually less than 90 degrees, which is difficult to achieve the hydrophobic performance required by the circuit board protective coating.

[0009] In summary, the existing circuit board protection materials generally have the problems of poor hydrophobicity, serious corner effect (easily leading to too thin coating at corner positions), and the formed protective coating is not easily punctured to affect the electrical connection of the connectors on the circuit board with other connectors, etc., which need to be solved urgently. SUMMARY

[0010] The present application provides a film-forming composition and its application to at least solve the problems of poor hydrophobicity, serious corner effect (easily leading to too thin coating at corner positions), and the formed protective coating is not easily punctured to affect the electrical connection of the connectors on the circuit board with other connectors, etc. of the existing circuit board protection materials.

[0011] In one aspect of the present application, a film-forming composition is provided, comprising the following components A-C: A, a hydrophobic polymer I, the hydrophobic polymer I being a solid polymer; B, a hydrophobic polymer II, the hydrophobic polymer II being a film-forming polymer; and C, an organic solvent.

[0012] According to one embodiment of the present application, the water drop angle of the hydrophobic polymer II is greater than or equal to 90 degrees.

[0013] According to one embodiment of the present application, the viscosity of the hydrophobic polymer II is greater than or equal to 10,000 mPa·S.

[0014] According to one embodiment of the present application, the hydrophobic polymer II comprises a liquid polymer.

[0015] According to one embodiment of the present application, the hydrophobic polymer II comprises silicone oil and / or linear polyolefin.

[0016] According to one embodiment of the present application, the water drop angle of the hydrophobic polymer I is greater than or equal to 90 degrees.

[0017] According to one embodiment of the present application, the hydrophobic polymer I comprises one or more of silicone resin, polyolefin, and fluorinated polymer.

[0018] According to one embodiment of the present application, the hydrophobic polymer I and the hydrophobic polymer II are of the same material.

[0019] According to one embodiment of the present application, the hydrophobic polymer I and the hydrophobic polymer II belong to a silicone system, or the hydrophobic polymer I and the hydrophobic polymer II belong to a polyolefin system.

[0020] According to one embodiment of the present application, the sum of the mass fractions of the hydrophobic polymer I and the hydrophobic polymer II is greater than or equal to 20% based on the total mass of the film-forming composition.

[0021] According to an embodiment of the present application, the mass fraction of the hydrophobic polymer I is greater than the mass fraction of the hydrophobic polymer II, based on the total mass of the film-forming composition.

[0022] According to an embodiment of the present application, after the organic solvent is volatilized, part of the hydrophobic polymer I is dissolved in the hydrophobic polymer II and physically mixed with the hydrophobic polymer II to form a film matrix, and another part of the hydrophobic polymer I is precipitated to form particulate matter during the volatilization of the organic solvent, and the particulate matter is dispersed in the film matrix.

[0023] According to another aspect of the present application, a structural member is provided, comprising: a substrate; an electronic component disposed on the substrate; a hydrophobic coating layer located on the side of the substrate where the electronic component is disposed and present on the surface of the electronic component; the hydrophobic coating layer is formed by the film-forming composition described above.

[0024] According to an embodiment of the present application, the water droplet angle of the hydrophobic coating layer is greater than or equal to 90 degrees.

[0025] According to an embodiment of the present application, the electronic component has a corner structure, the hydrophobic coating layer covers the corner structure, and the thickness of the hydrophobic coating layer covering the corner structure is greater than 5 μm.

[0026] According to an embodiment of the present application, the electronic component and / or the substrate has a planar region, the hydrophobic coating layer covers the planar region, and the thickness of the hydrophobic coating layer covering the planar region is 10 μm to 100 μm.

[0027] According to an embodiment of the present application, the electronic component includes a pin, and the surface of the pin has the hydrophobic coating layer.

[0028] According to an embodiment of the present application, the electronic component includes a connector, and the surface of the connector has the hydrophobic coating layer.

[0029] According to an embodiment of the present application, a plurality of electronic components are disposed on the substrate, and the hydrophobic coating layer is continuously distributed between and covers at least two adjacent electronic components.

[0030] According to another aspect of the present application, a terminal product is provided, comprising the above-mentioned structural member.

[0031] The implementation of the present application has at least the following beneficial effects:

[0032] (1) The film-forming composition of the present application has good hydrophobicity, and the formed hydrophobic coating has better waterproof effect, which can avoid corrosion, short circuit failure and other problems of the circuit board and other devices;

[0033] (2) The film-forming composition of the present application can avoid the corner effect, and can form a relatively thick protective coating at the corner position (such as the surface of 3D pin, etc.), so as to avoid that the protective coating at the corner position is too thin, thereby improving the protection effect of the circuit board and other devices.

[0034] (3) The protective coating formed by the film-forming composition of the present application has good flexibility and other properties, and the coating on the surface of the connector contact is easily pierced by the connecting terminal of the connector when being pressed by two matched connectors, so that the electrical connection between the two connectors can be realized, and the electrical conduction in the connector plugging process is not affected.

[0035] Therefore, the film-forming composition provided by the present application is a hydrophobic insulating material (insulating protective material) with good hydrophobicity and corrosion resistance, which is suitable for the protection of circuit boards and other electronic components, especially for the protection of circuit boards with connectors, and can form a protective coating on the surface of the circuit board and its connector and other components, thereby protecting the connectors and other devices on the circuit board and the entire circuit board, without affecting the electrical connection between the connectors on the circuit board and other connectors, and ensuring the thickness of the waterproof coating formed at the corner position of the circuit board assembly, thereby avoiding corrosion and short circuit failure at the corner position of the circuit board assembly. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 FIG. 1 is a structural schematic diagram of a circuit board with a surface forming a hydrophobic coating according to an embodiment of the present application;

[0037] Figure 2 FIG. 2 is a structural schematic diagram of a display module with a side surface forming a hydrophobic coating according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the scheme of the present application, the present application will be further described in detail below. The following specific embodiments are only used to describe the principles and characteristics of the present application, and the examples are only used to explain the present application, but not to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0039] The film-forming composition provided by the embodiment of the present application comprises components A-C: A, a hydrophobic polymer I (hereinafter referred to as polymer A), which is a solid polymer; B, a hydrophobic polymer II (hereinafter referred to as polymer B), which is a film-forming polymer; and C, an organic solvent (hereinafter referred to as solvent C).

[0040] In the embodiment of the present application, the film-forming composition can form a film at room temperature, i.e., when the film-forming composition is applied, the film-forming composition is coated on the device to be protected (such as the predetermined surface of a circuit board with connectors, etc.), and then the solvent C is volatilized at room temperature. After the solvent C is completely volatilized, the physical mixture of the polymer A and the polymer B forms a non-flowable film layer (or a protective coating, or a protective layer, or a protective adhesive layer, or a hydrophobic coating).

[0041] In the film-forming process, the polymer A and the polymer B do not undergo chemical reactions, i.e., in the physical blend of the polymer A and the polymer B, the polymer A and the polymer B are only physically mixed, and there is no chemical bond between them, and no chemical cross-linking reaction occurs. Thus, the film layer formed by the polymer A and the polymer B is easily pierced or pushed away when subjected to an external force, so that the film-forming composition and the hydrophobic coating formed by the film-forming composition are suitable for a circuit board with connectors. When the hydrophobic coating is formed on the circuit board with connectors, the film layer can cover the connectors to protect the connectors and prevent the connectors from short-circuiting, failing, etc. At the same time, when the connector of the circuit board is connected to another connector, the hydrophobic coating present at the contact part (connection terminal) of the connector can be pierced or pushed away under the extrusion of the connection terminals of the two connectors, thereby realizing the electrical connection of the connection terminals of the two connectors. Meanwhile, the hydrophobic coating has good flexibility and other properties, and the hydrophobic coating at other parts (non-contact parts) on the surface of the connector is not damaged. Thus, after the connector is plugged in, the hydrophobic coating (insulating protective material) still exists between the terminals of different connectors, thereby maintaining the protection effect on the connector and the circuit board and preventing problems such as water-induced short-circuiting and corrosion failure.

[0042] Generally, the above-mentioned physical blend (film layer) can include a film matrix and particles present in the film matrix. The film matrix mainly comprises the polymer A and the polymer B, i.e., it is mainly formed by the physical mixing of the polymer A and the polymer B. The particles mainly comprise the polymer A, i.e., they are mainly formed by the polymer A, and are randomly distributed in the film matrix. The average size (particle size) of the particles is in the micron level, e.g., 2-100 μm, such as 2 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a range formed by any two of them.

[0043] Specifically, after the solvent C is volatilized, part of the polymer A is dissolved in the polymer B and physically mixed with the polymer B to form the film matrix, and the other part of the polymer A is precipitated in the form of particles during the volatilization of the solvent C, and the particles are dispersed in the film matrix (i.e., this part of the polymer A is precipitated in the form of particles and dispersed in the film matrix).

[0044] Generally, during the volatilization of the solvent C, most of the polymer A in the film-forming composition is dissolved in the polymer B, thereby physically mixed with the polymer B to form the film matrix, and a small part of the polymer A is precipitated from the composition to form particles, i.e., after the solvent C is volatilized, most of the polymer A enters the film matrix, and a small part of the polymer A exists in the film matrix in the form of particles, the proportion of the polymer A in the film matrix to the total mass of the polymer A in the film-forming composition is greater than 50%, and the total mass of the polymer A in the film-forming composition (also the total mass of the polymer A in the hydrophobic coating) is substantially equal to the sum of the mass of the polymer A in the film matrix and the mass of the particles (i.e., the mass of the polymer A forming the particles).

[0045] In a specific implementation, the hydrophobic coating can be sliced, and the area proportion of the particles in a preset region of the cross section (section) of the hydrophobic coating is detected by a microscope. According to the detection result, the preset region (the region observed by the microscope) has particles, and the area proportion of the particles (i.e., the ratio of the area occupied by the particles in the preset region to the total area of the preset region) is less than 50%, usually less than 25%, and specifically less than 10%. The hydrophobic coating is mainly formed by the polymer A and the polymer B, both of which are polymers and have substantially the same density. Therefore, the proportion of the polymer A forming the particles to the total mass of the polymer A in the film-forming composition is approximately equal to the area proportion of the particles, i.e., the proportion of the polymer A forming the particles to the total mass of the polymer A in the film-forming composition is less than 50%, and accordingly, the proportion of the polymer A in the film matrix to the total mass of the polymer A in the film-forming composition is greater than 50%. The microscope used can be a conventional high-power optical microscope in the art, and the magnification of the high-power optical microscope can be 200-1000 times when detecting the cross section of the hydrophobic coating.

[0046] In the related art, in order to improve the viscosity, flowability and hydrophobicity of the film-forming composition, it is usually necessary to add fillers (for example, hydrophobic fillers) to the film-forming composition, but the fillers and the organic base material of the film-forming composition are not the same material system, and the compatibility between them is poor, and after forming a protective coating, phase separation phenomenon is easy to occur. Specifically, the fillers and the organic base material have different flowabilities under external force, which leads to phase separation, for example, the fillers are enriched in a local position in the protective coating, and the dispersion uniformity in the protective coating is poor. In the embodiments of the present application, the film-forming composition has suitable viscosity and flowability, which can avoid the corner effect, and in the hydrophobic coating formed by the film-forming composition, the particulate matter and the film matrix belong to the polymer material system, and the material of the particulate matter is mainly polymer A, and polymer A also exists in the film matrix, so that they have good compatibility, and the hydrophobic coating is not prone to phase separation (separation of particulate matter and film matrix) and other problems.

[0047] Specifically, in the embodiments of the present application, in the hydrophobic coating formed by the film-forming composition, the particulate matter is formed by precipitation of polymer A in the film-forming composition, and has good flexibility and micron-level size. After the film-forming composition is used to form a hydrophobic coating on the surface of a circuit board provided with a connector, in the process of multiple and long-time plugging of the connector and other connectors, under the action of the fitting force of the two connector terminals, the particulate matter in the hydrophobic coating can move with the film matrix, and phase separation does not occur, thereby not affecting the performance of the connector plugging, and not affecting the connection reliability of the two connectors under multiple plugging.

[0048] In addition, polymer A is supersaturated with respect to polymer B, that is, during the volatilization of solvent C, there is polymer A that is not dissolved in polymer B, and this part of polymer A precipitates in the form of particles, which can further increase the viscosity of the physical mixture formed by dissolving polymer A in polymer B, thereby improving the thixotropic properties of the physical mixture (thixotropic properties generally refer to shear thinning, that is, the viscosity of the material decreases after encountering external stress, and the viscosity of the material recovers after the external force disappears), reducing the flowability of the physical mixture, thereby avoiding the corner effect, and avoiding problems such as thin coating thickness and poor protection effect on the corner structure surface (such as the 3D pin) of the device.

[0049] Generally, based on the total mass of the film-forming composition, the mass fraction of polymer A is greater than the mass fraction of polymer B, that is, the mass content of polymer A in the film-forming composition is greater than the mass content of polymer B, which is beneficial to the precipitation of part of polymer A in the form of particles during the volatilization of solvent C, that is, to form particulate matter dispersed in the film matrix.

[0050] For example, the mass ratio of polymer A to polymer B can be greater than or equal to 5:3, and specifically can be (5-30):3, such as 5:3, 8:3, 10:3, 12:3, 15:3, 18:3, 20:3, 23:3, 25:3, 28:3, 30:3, or a range consisting of any two of them.

[0051] In the embodiments of the present application, polymer A can be dissolved in polymer B, that is, after mixing polymer A and polymer B in a proper ratio and after sufficient stirring, a uniform mixture without suspended phase can be formed. The uniform state of the mixture can be a long-term state, for example, the uniform state can be maintained for a long time without suspended phase appearing after standing at room temperature, or the uniform state of the mixture can be a short-term state, for example, the uniform state can be achieved without suspended phase under the action of stirring or heating.

[0052] Generally, the mixing ratio of polymer A in polymer B is lower than the solubility of polymer A in polymer B (that is, the solubility of polymer A in polymer B is x%, that is, a maximum of x g of polymer A can be dissolved in 100 g of polymer B on average, and then the mixing ratio of polymer A and polymer B is lower than x% (that is, the amount of polymer A added in 100 g of polymer B is lower than x g on average)), and polymer A can be completely dissolved in polymer B to form a mixture in a uniformly dispersed state without suspended phase, and the mixture can be transparent.

[0053] In some preferred embodiments, the uniform state of the mixture formed after polymer A is dissolved in polymer B is long-term. In specific implementation, the long-term uniform state of the mixture of polymer A and polymer B can be achieved by adjusting the types and amounts of polymer A and polymer B, and the film-forming composition is formed according to such conditions.

[0054] According to further research by the inventors, during the volatilization of solvent C, the non-flowable polymer A is dissolved in the polymer B with good flowability, and by adjusting the solid content of the film-forming composition and other conditions, the flowability of the physical blend formed by the dissolution of polymer A in polymer B during the volatilization of solvent C can be further improved, so that it is difficult to flow or substantially non-flowable, and especially the supersaturation of polymer A with respect to polymer B can be achieved, so that part of polymer A is precipitated to form particulate matter dispersed in the physical blend, to further improve the thixotropic properties and other properties of the physical blend, and to avoid problems such as the film layer formed on the surface of the corner structure of the device being too thin. Generally, in order to achieve good corrosion protection effect, the film layer thickness at the corner position (such as the pin) of the device can be greater than 5 μm, and more preferably greater than or equal to 10 μm.

[0055] Taking the above factors into consideration, the solid content of the film-forming composition (the sum of the mass fractions of polymer A and polymer B, based on the total mass of the film-forming composition) can be greater than or equal to 20%, preferably greater than or equal to 25%.

[0056] Thus, in the embodiments of the present application, by adding polymer A and other components in the film-forming composition, the viscosity of the film-forming composition can be increased, specifically the viscosity of the film-forming composition can be greater than or equal to 20%, so that when the film-forming composition is applied to the surface of a device such as a circuit board with a connector, the problem of the film layer formed at the corner position being too thin due to the excessive flowability of the film-forming composition can be avoided, and specifically the film layer thickness on the surface of the corner structure can be greater than or equal to 10 μm.

[0057] In addition, solvent C is mainly used to dissolve and disperse polymer A and polymer B, reduce the viscosity of the film-forming composition, so that it can be coated by processes such as spot coating (jet spot coating), spray coating (atomization spray coating), curtain coating (curtain coating), dip coating, brush coating, etc. (i.e. the film-forming composition can be applied to the surface of a device such as a connector by these processes), and at the same time helps the film-forming performance of the film-forming composition, such as forming a film layer with a lower thickness as needed, etc.

[0058] Specifically, in the film-forming composition, the mass percentage content of solvent C (i.e. the ratio of the mass of solvent C to the total mass of the film-forming composition) can be less than or equal to 80%, further less than or equal to 75%.

[0059] In some embodiments, in the film-forming composition, the mass percentage content of solvent C can be 15% to 80%, such as 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or a range consisting of any two of them.

[0060] Specifically, in the film-forming composition, the mass percentage content of polymer A (i.e. the ratio of the mass of polymer A to the total mass of the film-forming composition) can be greater than or equal to 10% and less than or equal to 80% (i.e. the mass percentage content of polymer A can be 10% to 80%), such as less than or equal to 50%.

[0061] Exemplarily, in the film-forming composition, the mass percentage content of polymer A can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or a range consisting of any two of them.

[0062] Specifically, the mass percentage of the polymer B in the film-forming composition (i.e., the ratio of the mass of the polymer B to the total mass of the film-forming composition) can be less than or equal to 40%, for example, less than or equal to 20%, or less than or equal to 15%.

[0063] In some embodiments, the mass percentage of the polymer B in the film-forming composition can be in the range of 3-40%, for example, 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or a range between any two of them.

[0064] Specifically, the polymer A or the polymer B can be dissolved in the solvent C, i.e., the polymer A or the polymer B and the polymer C can form a uniform, transparent, and homogeneous mixture system without suspended phase after mixing, and such a uniform state can exist for a long time, but is not limited thereto.

[0065] In some preferred embodiments, in order to improve the process performance of the film-forming composition, the solvent C can completely dissolve the polymer A and the polymer B in the film-forming composition, i.e., the polymer A and the polymer B are completely dissolved in the solvent C, at this time, the film-forming composition is a uniform, transparent, and homogeneous mixture system without suspended phase, which is beneficial to the film-forming composition having a lower viscosity, and can further improve the process performance of the film-forming composition, and is suitable for processes such as atomization spraying, jet point coating, point gluing, curtain coating, dipping, and brushing, i.e., the film-forming composition can be applied to devices such as circuit boards by these processes for film formation.

[0066] Specifically, the viscosity of the film-forming composition can be less than or equal to 1000 mPa·S, which is beneficial to the film-forming composition being coated into a film by processes such as atomization spraying, jet point coating, point gluing, curtain coating, dipping, and brushing.

[0067] In some embodiments, when the viscosity of the film-forming composition is less than or equal to 1000 mPa·S, the mass percentage of the solvent C in the film-forming composition can be greater than or equal to 30% (correspondingly, the solid content of the film-forming composition is less than 70%), at this time, the mass percentage of the polymer A is less than 70%, and the mass percentage of the polymer B can be less than 40%.

[0068] In some specific embodiments, the viscosity of the film-forming composition can be in the range of 3-1000 mPa·S, for example, 3 mPa·S, 5 mPa·S, 10 mPa·S, 30 mPa·S, 50 mPa·S, 80 mPa·S, 100 mPa·S, 120 mPa·S, 150 mPa·S, 180 mPa·S, 200 mPa·S, 300 mPa·S, 400 mPa·S, 500 mPa·S, 600 mPa·S, 700 mPa·S, 800 mPa·S, 900 mPa·S, 1000 mPa·S, or a range between any two of them.

[0069] However, the solubility of polymer A and polymer B in solvent C, and the viscosity of the film-forming composition, etc. are not limited to the above-mentioned embodiments. For example, in some other embodiments, when the atomization spraying process is not required, the viscosity of the film-forming composition can also be greater than 1000 mPa s. In this case, solvent C is allowed to not completely dissolve polymer A and polymer B, and the mass percentage of solvent C in the film-forming composition can be less than 30% (correspondingly, the solid content of the film-forming composition is greater than or equal to 70%), and generally less than 20% (correspondingly, the solid content of the film-forming composition is greater than or equal to 80%), and in this case, the mass percentage of polymer A is less than 80%, and the mass percentage of polymer B can be less than 40%.

[0070] In the embodiments of the present application, polymer A is a solid polymer, which has substantially no flowability, i.e. polymer A alone usually presents a non-flowable solid form at room temperature, and when the molecular weight of polymer A is low, it can also flow under certain force.

[0071] In addition, polymer A has hydrophobicity, and the water droplet angle (water contact angle) thereof can be greater than or equal to 90 degrees (°), and further can be greater than or equal to 100°, which is beneficial to the formed film layer having good hydrophobicity.

[0072] In some specific embodiments, the water droplet angle of polymer A can be 90° to 120°, for example, 90°, 92°, 95°, 98°, 100°, 102°, 104°, 105°, 108°, 110°, 115°, 120° or a range formed by any two of them.

[0073] In addition, polymer A, in addition to being combined with polymer B and other components to regulate the viscosity of the film-forming composition and achieve a non-flowable film layer, can also improve the mechanical properties of the film layer formed by the film-forming composition, for example, it can regulate the softness and hardness of the film layer formed on the surface of the connector and other devices, improve the thickness and mechanical properties of the film layer on the surface of the corner structure (such as the edge of the corner) of the device, and further improve the protection effect of the device.

[0074] Specifically, the polymer A can include a polymer in a cross-linked molecular structure, i.e., its molecular structure is in a cross-linked network structure, the polymer A can include one or more organic polymers in a cross-linked molecular structure, in some embodiments, the polymer A can include one or more of a silicone resin (cross-linked silicone resin), a polyolefin, a fluorinated polymer. Among them, the silicone resin can specifically include a functionalized silicone resin, for example, including a methyl silicone resin and / or a phenyl silicone resin, the methyl silicone resin (or dimethyl silicone resin) is a polydimethylsiloxane with a cross-linked structure; the outer layer of the molecular of the fluorinated polymer generally has a layer of fluorine (F) functional group, so that the fluorinated polymer is hydrophobic, the fluorinated polymer can include one or more of a fluorinated polyester, a fluorinated polyacrylate, a fluorinated silicone resin, etc.

[0075] Specifically, the polymer A can be in a plurality of molecular weight distribution states, for example, the polymer A can include a plurality of organic polymers with the same chemical formula unit, and the molecular weights of these organic polymers are different, for example, the polymer A can include an organic silicone resin with a molecular weight distribution of M1 and an organic silicone resin with a molecular weight distribution of M2.

[0076] Specifically, the polymer A can be a non-polar polymer, for example, including a non-polar silicone resin, the non-polar organic resin has good flexibility, which is beneficial to the formed film layer having good flexibility.

[0077] In some embodiments, in order to improve the performance of the circuit board assembly in resisting gas corrosion (such as sulfurization resistance), the polymer A can include a high cross-linking density silicone resin, for example, a phenyl silicone resin.

[0078] In the embodiments of the present application, the polymer B has hydrophobicity, and the water drop angle thereof can be greater than or equal to 90°, further can be greater than or equal to 95°, or greater than or equal to 100°, which is beneficial to the formed film layer having good hydrophobicity.

[0079] In some specific embodiments, the water drop angle of the polymer B can be 90°-120°, for example, 90°, 95°, 100°, 105°, 110°, 115°, 120° or a range formed by any two of them.

[0080] In the embodiments of the present application, the polymer B is a film-forming material, which has good fluidity (i.e., it has good fluidity when it exists alone), and the polymer B can specifically include a liquid polymer that can be used for film formation, which is in a liquid state at room temperature when it exists alone, and specifically can be in an oil state when it exists alone, so that it has good film-forming performance and can be used for film formation, and at the same time can dissolve the polymer A to form a physical blend with high viscosity, so as to realize film formation on a 3D complex shape surface.

[0081] Specifically, the polymer B can include a linear polymer of a linear molecular structure (i.e., its molecular structure is in a linear structure) and / or a cross-linked polymer of a low cross-linking degree, for example, the polymer B can include one or more organic polymers of a linear molecular structure (linear polymer) and / or one or more cross-linked polymers of a low cross-linking degree.

[0082] In some embodiments, the polymer B can include a silicone oil and / or a linear polyolefin, wherein the silicone oil specifically can include a linear silicone oil and / or a cross-linked silicone oil of a low cross-linking degree (cross-linked polymer of a low cross-linking degree).

[0083] Specifically, the silicone oil can include one or more of a polysiloxane, and a copolymer of a first monomer and a second monomer, etc., wherein the first monomer is a siloxane-based polymer, which specifically can include one or more of a polysiloxane, a polysiloxane methacrylate, etc., the polysiloxane can include a polydimethylsiloxane, the polysiloxane methacrylate can include a polymethyltrimethylsiloxane methacrylate, and the second monomer can include one or more of a methylsiloxane, a diphenylsiloxane, a phenylmethylsiloxane, a trimethylsiloxysilicate, an acrylic acid (ester), an alkane, or a polymer polymerized from at least two of these compounds, etc.

[0084] Among them, the linear silicone oil can include a linear polysiloxane (polysiloxane of a linear structure), for example, a linear polydimethylsiloxane (linear dimethyl polysiloxane).

[0085] Among them, the cross-linked silicone oil of a low cross-linking degree can include a polysiloxane of a low cross-linking degree and / or a copolymer of the above-mentioned first monomer and second monomer.

[0086] Exemplarily, the cross-linked polymer of a low cross-linking degree can include one or more of a polydimethylsiloxane / methylsiloxane, a polydimethylsiloxane / methylsiloxane / diphenylsiloxane, a polydimethylsiloxane / methylsiloxane / phenylmethylsiloxane, a polydimethylsiloxane / phenylmethylsiloxane, a polydimethylsiloxane / diphenylsiloxane, a polydimethylsiloxane (and) trimethylsiloxysilicate, a polydimethylsiloxane (and) acrylic acid (ester) / polymethyltrimethylsiloxane methacrylate copolymer, an alkane (and) acrylic acid (ester) / polymethyltrimethylsiloxane methacrylate copolymer, etc.

[0087] In the embodiments of the present application, "A / B", "A (and) B" each respectively represent a copolymer of A and B, for example, "polydimethylsiloxane / methylsiloxane" refers to a copolymer of polydimethylsiloxane and methylsiloxane; "acrylic acid (ester)" represents an acrylic acid and / or an acrylic ester.

[0088] Specifically, cross-linked polymers (cross-linked silicone oils) with a low degree of cross-linking are usually prepared by chain addition reactions of two types of polysiloxanes, namely linear polysiloxane a (linear silicone oil) and linear polysiloxane b (linear silicone oil), wherein polysiloxane a is a linear silicone oil with the following molecular structure, as shown in the following schematic diagram:

[0089] Polysiloxane a

[0090] Among them, R1 can be selected from hydrogen groups, alkenyl groups (such as vinyl groups), etc.; R2 can be selected from alkyl groups, aryl groups, cycloalkyl groups, and other functional groups (such as ether, carboxyl groups, amino groups, sulfonic acid groups, hydroxyl groups, ester groups, mercapto groups), etc.

[0091] Generally, the linear polysiloxane b contains m groups that can react with R1 in the polysiloxane a, where m is an integer greater than or equal to 1, specifically 1 or 2; and n is an integer representing the number of repeating segments.

[0092] In short, the above-mentioned cross-linked silicone oil (polymer B) is prepared by a chain addition reaction of two or more silicone oils (linear), and the number of reactive groups between the linear silicone oils is m, preferably not more than 2 (i.e., preferably 1≤m≤2).

[0093] In general, cross-linked silicone polymers usually contain R 2 SiO 2 / 2 、R 3 SiO 1 / 2 、RSiO 3 / 2 、SiO 4 / 2 Unit, where R 2 Represents R 2 SiO 2 / 2 There are two R connected to Si in the unit, R 3 Represents R 3 SiO 1 / 2 There are three Rs connected to the Si in the unit. The more Rs there are, the lower the cross-linking degree of the cross-linked silicone polymer. For cross-linked silicone oil, the units that constitute the repeating chain of the polymer are mainly composed of R2SiO 2 / 2、 RSiO 3 / 2 Composition, does not contain SiO 4 / 2 Units, while for cross-linked silicone resins (organic silicone resins), the units that constitute the repeating segments of the polymer are mainly SiO 4 / 2 Unit (SiO 4 / 2 In the unit, one Si connects to four O, the bond is short and the cross-linking degree is high).

[0094] Generally, cross-linked silicone resin can be prepared by chain addition reaction of two or more silicone oils (linear), and the silicone oil acting as a cross-linking agent contains more than or equal to 3 reactive groups.

[0095] Specifically, the polymer B can be in a plurality of molecular weight distribution states, for example, the polymer B can include a plurality of organic polymers having the same chemical formula unit, and the molecular weights of the organic polymers are different, for example, the polymer B can include an organic silicone oil with a molecular weight distribution of M3 and an organic silicone oil with a molecular weight distribution of M4.

[0096] In the embodiments of the present application, the materials such as silicone resin, silicone oil, solvent, etc. can be obtained by commercial purchase, etc., and no particular limitation is made thereto.

[0097] Specifically, the materials of the polymer A and the polymer B can be the same, i.e. the polymer A and the polymer B belong to the same material system, for example, the polymer A and the polymer B both belong to the silicone system (the polymer A is a silicone resin and the polymer B is a silicone oil), or both belong to the polyolefin system (the polymer A is a cross-linked polyolefin and the polymer B is a linear polyolefin), at this time, it is beneficial to improve the solubility of the polymer A in the polymer B, and at the same time, in the film layer formed by the film-forming composition, the particulate matter and the film matrix belong to the same material system, have better compatibility, and are less likely to have phase separation and other problems, which is beneficial to improve the protection effect on the circuit board and other devices.

[0098] Generally, when the materials of the polymer A and the polymer B are the same, the infrared spectrum of the polymer A has high similarity with the infrared spectrum of the polymer B.

[0099] Of course, in the embodiments of the present application, the materials of the polymer A and the polymer B can also be different, i.e. the polymer A and the polymer B belong to different material systems, but both belong to the polymer system, and in the film layer formed by the film-forming composition, the particulate matter and the film matrix still maintain good compatibility and are less likely to have phase separation and other problems between the particulate matter and the film matrix.

[0100] Generally, the non-polar organic polymer is hydrophobic, and the non-polar polymer is, for example, a polyolefin (such as the above-mentioned cross-linked polyolefin (polymer A) and linear polyolefin (polymer B) and the like), and the polyolefin includes, for example, polyethylene, polypropylene, polystyrene, etc.

[0101] In addition, when the branches on the molecular main chain of the organic polymer are symmetrical structures, and the branch groups are mainly non-polar functional groups, the surface of such organic polymer is hydrophobic (also known as hydrophobic), and since the silicone polymer (polysiloxane) generally has a layer of non-polar organic groups on the outer layer of the molecule, and based on the symmetry of its molecular structure, the silicone polymer (such as the above-mentioned silicone resin and silicone oil) is hydrophobic.

[0102] Specifically, the organic silicon polymer is a common hydrophobic material, and a polysiloxane with a highly cross-linked molecular structure in a cross-linked structure / network structure is referred to as an organic silicon resin, and a polysiloxane with a linear molecular structure or a polysiloxane with a low cross-linking degree is referred to as an organic silicon oil.

[0103] In some embodiments, the molecular structure unit of the organic silicon resin is shown in formula 1, in which R3 is a side chain group, and the side chain groups at different positions can be the same or different.

[0104] Specifically, R3 in formula 1 can be a non-polar group such as an alkyl group (such as a methyl group) or a phenyl group, and R3 is preferably a functional group without reactivity, for example, a functional group selected from a -H group, an -OH group, a vinyl group, an alkoxy group, and the like, so as to avoid possible chemical reactions under comprehensive conditions such as humidity and high temperature, thereby causing deterioration of the performance of the final protective coating. A small number of side chain groups R3 can also be polar functional groups, or functional groups with reactivity, such as a side chain containing a -H group, an -OH group, a vinyl group, an alkoxy group, an epoxy group, an F group, an H group, an OH group, an ester group, an ether group, and the like.

[0105]

[0106] For example, the organic silicon resin is a methyl organic silicon resin, that is, R3 in formula 1 is a methyl group.

[0107] In some embodiments, the molecular structure of the organic silicon oil is shown in the following formula 2, in which R4, R5, R6, R7, R8, R9, R 10 , and R 11 are side chain groups, R4 to R 11 may be the same or different, and these side chain groups can contain any one of a functional group such as an alkyl group, a phenyl group, a -H group, an -OH group, a vinyl group, an alkoxy group, an epoxy group, an F group, an H group, an OH group, an ester group, an ether group, and the like, and the side chain group is preferably a non-polar group without reactivity, for example, an alkyl group (such as a methyl group, an ethyl group, a propyl group, and the like), a phenyl group, and the like.

[0108]

[0109] For example, the above-mentioned organic silicon oil is a linear polydimethylsiloxane, that is, R4, R5, R6, R7, R8, R9, R 10 , and R 11 in formula 2 are methyl groups.

[0110] In the above-mentioned organic silicon polymer, the number of R functional groups (the number of R3 in formula 1, the number of R4 to R 11The ratio of the total number of R groups to the number of Si atoms (R / Si value) has a large effect on the properties of the silicone polymer. Typically, the R / Si value of a silicone oil is > 2, the R / Si value of a silicone resin is < 2, and preferably the R / Si value of a silicone resin is < 1.6.

[0111] Generally, the viscosity of the polymer B can be greater than or equal to 10,000 mPa s (10 million mPa s), i.e., the hydrophobic polymer II having a viscosity greater than or equal to 10 million mPa s can be used in the embodiments of the present application, which is conducive to improving the viscosity of the film-forming composition, avoiding the corner effect of the film-forming composition, and avoiding the formation of a film layer that is too thin on the corner structure surface of the device, while improving the film-forming performance of the film-forming composition.

[0112] In some embodiments, the viscosity of the polymer B can be 1 million mPa s to 60 million mPa s, such as 1 million mPa s, 1.5 million mPa s, 2 million mPa s, 2.5 million mPa s, 3 million mPa s, 3.5 million mPa s, 4 million mPa s, 4.5 million mPa s, 5 million mPa s, 5.5 million mPa s, 6 million mPa s, or a range defined by any two of them.

[0113] Generally, when the viscosity of the polymer B is too large (e.g., greater than 10 million mPa s), the solvent C can be added to the polymer B first to reduce its viscosity, and then the film-forming composition can be prepared (i.e., the polymer A, the polymer B with the solvent C added, and the solvent C are mixed to prepare the film-forming composition), which is conducive to the uniform mixing of the components and avoids phenomena such as stratification, opacity, and emulsion.

[0114] Specifically, the film-forming composition or the film layer formed by the film-forming composition can be subjected to separation treatment such as extraction to separate the polymer A and the polymer B, and the separated polymer A is in a solid state at room temperature (i.e., the polymer A in the film-forming composition is a solid polymer), and the separated polymer B is in a liquid state at room temperature (i.e., the polymer B in the film-forming composition is a liquid polymer).

[0115] Generally, the polymer A and the polymer B can satisfy the condition that the viscosity of the mixture (not containing the solvent C or other components) of the polymer A and the polymer B is greater than 10 million mPa s, which is conducive to further improving the film-forming performance of the film-forming composition.

[0116] As described above, the film layer formed by the film-forming composition is mainly formed by the physical blend of the polymer A and the polymer B, and thus the viscosity of the film layer formed by the solidification of the film-forming composition is substantially equal to the viscosity of the mixture of the polymer A and the polymer B, and the viscosity of the film layer is generally also greater than 10 million mPa s.

[0117] In the embodiments of the present application, during the process of applying the film-forming composition on the surface of the device and solidifying the film, the solvent C volatilizes, and the formed film layer is mainly formed by the physical blend of the polymer A and the polymer B (including the film matrix and the particulate matter formed by the polymer A), wherein the solvent C can volatilize through at least one of the following processes: (1) volatilization after the film-forming composition is coated on the device; (2) volatilization during the process of coating the film-forming composition on the surface of the device, and a small amount of residual solvent C volatilizes after the coating is completed, but not limited thereto.

[0118] Specifically, the solvent C can include a non-polar solvent and / or a polar solvent, and can specifically include one or more of alcohols, hydrocarbons, ethers, ketones, halogenated hydrocarbons, aldehydes, organosilicon, etc. Among them, the alcohols can include one or more of methanol, ethanol, and propanol, etc.; the hydrocarbons can include aliphatic hydrocarbons, which can include alkanes, and can specifically include paraffins and / or isoparaffins, for example, one or more of hexane, isooctane, and decane (such as n-decane), etc.; the ethers can include furans (such as tetrahydrofuran) and / or dialkyl ethers (such as diethyl ether); the halogenated hydrocarbons can include fully halogenated hydrocarbons and / or partially halogenated hydrocarbons; the organosilicon is generally a low molecular weight silicone oil (i.e. silicone oil type solvent, which generally has a molecular weight less than 1000), which can include linear organosilicon and / or cyclic organosilicon, for example, including decamethylcyclopentasiloxane (D5). The solvent C can be one of them, or a mixed solvent containing multiple solvents, for example, the solvent C can be a low molecular weight mineral oil mainly composed of alkanes and aromatic hydrocarbons.

[0119] In the embodiments of the present application, in order to further improve the performance of the film-forming composition and the film layer formed by the above-mentioned film-forming composition, one or more of the functional additives such as leveling agents, stabilizers, anti-aging agents, and fluorescent indicators can be included in the film-forming composition, and these functional additives can all be conventional materials in the field, and are not particularly limited.

[0120] In the embodiments of the present application, in order to further improve the performance of the film-forming composition, such as hydrophobicity or oleophobicity, a hydrophobic filler and / or an oleophobic filler can be included in the film-forming composition, for example, the hydrophobic filler can include insulating silica particles that are surface treated with silane, the oleophobic filler can include insulating silica particles that are surface treated with fluorine-based materials, etc., but not limited thereto.

[0121] The film layer formed by the film-forming composition has good hydrophobicity, the water drop angle of the film layer can be greater than or equal to 90°, and further can be greater than or equal to 100°, and good protection effect on electronic components such as circuit boards can be achieved. Research shows that when the film-forming composition of the embodiment of the present application is used to form a film layer on the surface of a connector or the like, even if there are defects of hundreds of microns in size on the surface or internal local position of the film layer (such as the film layer at the corner position of the device), due to the good hydrophobicity of the film layer, water can be prevented from contacting the device, preventing the device from corroding, and short circuit failure and other problems are not prone to occur in the water immersion scene.

[0122] The film-forming composition of the embodiment of the present application is suitable for protecting structural components such as circuit board assemblies, and is particularly suitable for application scenarios where connectors are assembled on circuit boards. The circuit board (PCB) is part of an electronic device, which can be a consumer electronic device such as a smart phone, a smart watch, a smart door lock, a smart tablet, a PC, a home network terminal, etc., or a communication electronic device such as a wireless communication base station, an access network device, etc., or an industrial electronic device such as a power supply, a controller, etc. The circuit board can be a rigid PCB or a flexible PCB, etc.

[0123] The embodiment of the present application also provides a structural component, comprising: a substrate; an electronic component disposed on the substrate; a hydrophobic coating layer located on the side of the substrate where the electronic component is disposed and present on the surface of the electronic component; the hydrophobic coating layer is formed by the above-mentioned film-forming composition.

[0124] Specifically, the substrate can include a circuit board, but is not limited thereto.

[0125] Specifically, the electronic component can include one or more of a connector, a wing-shaped pin device, a chip electronic component (such as a chip resistor, a chip capacitor), an integrated circuit (IC) assembly, a power supply chip, a packaged device (such as a SOP packaged device), a display screen module, etc. The connector can include a board-to-board connector, a BTB connector, a board-to-cable connector, a radio frequency connector, a power connector, an IC socket connector, a video / USB / audio special interface connector, etc.

[0126] When the connector is mounted on the substrate, the surface of the connector has a hydrophobic coating layer, which can achieve protection of the connector while not affecting the electrical connection of the connector with other connectors.

[0127] Specifically, the water drop angle of the hydrophobic coating layer can be greater than or equal to 90°, and further can be greater than or equal to 100°, and has good hydrophobicity, which can improve the protection effect of the connector and other devices on the structural component.

[0128] In some embodiments, the water droplet angle of the hydrophobic coating can be 90° to 120°, such as 90°, 95°, 100°, 105°, 110°, 115°, 120°, or a range defined by any two of them.

[0129] In the embodiments of the present application, the hydrophobic coating exists on the surface of the structural member and the electronic components (electronic parts) arranged on the structural member, the electronic components include components sensitive to external pollution conditions such as oil, salt water, etc., the surfaces of these components are exposed to the air, and by forming a hydrophobic coating on the surface thereof, corrosion of these components can be avoided.

[0130] Specifically, the electronic component and / or the substrate have a planar region (such as Figure 1 the third planar region 10, the first planar region 210, the second planar region 220, etc. in FIG. 1), the hydrophobic coating covers the planar region, and the thickness of the hydrophobic coating covering the planar region (i.e., the hydrophobic coating on the surface of the planar region) can be 10 μm to 100 μm, such as 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a range defined by any two of them.

[0131] In addition, the electronic component has a corner structure (such as Figure 1 the corner position in the region Q1, the region Q2, the region Q3, the region Q4, etc. in FIG. 1), the hydrophobic coating covers the corner structure, and due to factors such as the corner effect, the hydrophobic coating covering the corner structure (i.e., the hydrophobic coating on the surface of the corner structure) is the thinnest part of the entire hydrophobic coating, and the thickness of the hydrophobic coating covering the corner structure is less than the thickness of the hydrophobic coating covering the planar region (such as Figure 1 the thickness of the hydrophobic coating on the surface of the corner structure in the region Q1, the region Q2, the region Q3, the region Q4, etc. in FIG. 1 is less than the thickness of the hydrophobic coating on the planar region (such as the third planar region 10, the first planar region 210, the second planar region 220, etc.).

[0132] In the embodiments of the present application, the thickness of the hydrophobic coating covering the corner structure can be greater than or equal to 5 μm, and further can be greater than or equal to 10 μm.

[0133] In some embodiments, the thickness of the hydrophobic coating covering the corner structure can be 5 μm to 20 μm, such as 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, or a range defined by any two of them.

[0134] Specifically, the electronic component includes a pin, the surface of the pin has a hydrophobic coating, and the pin has a corner structure, the thickness of the hydrophobic coating on the surface of the corner structure can be greater than or equal to 5 μm, and further can be greater than or equal to 10 μm.

[0135] Generally, the above-mentioned pins can be 3D pins, such as wing-shaped pins of wing-shaped pin devices, soldering end pins of chip electronic components, SOP pins of SOP packaged devices, pins (terminals) of connectors, etc.

[0136] In the embodiments of the present application, the thickness of the hydrophobic coating of any part refers to the distance (usually the minimum distance) from the side of the hydrophobic coating of the part in contact with the electronic component (or substrate) to the side of the hydrophobic coating of the part away from the electronic component (or substrate). For example, as shown in FIG. 1, the thickness of the hydrophobic coating 3 on the third planar region 10 refers to the distance from the side of the hydrophobic coating 3 on the third planar region 10 in contact with the substrate to the side of the hydrophobic coating 3 away from the substrate, and the thickness of the hydrophobic coating 3 on the corner structure in region 1 refers to the distance from the side of the hydrophobic coating 3 away from the soldering end pin 211 to the side of the hydrophobic coating 3 in contact with the soldering end pin 211. Figure 1

[0137] Specifically, the substrate is provided with a plurality of electronic components, and the hydrophobic coating is continuously distributed between and covers at least two adjacent electronic components.

[0138] Generally, when there is a water droplet inside the electronic device, the water droplet will contact the exposed contacts of the electronic components such as connectors, thereby causing corrosion of the exposed contacts of the electronic components. Therefore, a hydrophobic coating needs to be provided on the surface of the exposed contacts of the electronic components, and preferably, a hydrophobic coating is provided on the surface of the electronic components including the surface of the exposed contacts, such as the surface of the circuit board, the surface of the chip electronic components provided on the circuit board, the surface of the packaged devices, and the surface of the connectors. The hydrophobic coating is distributed in the form of a film on the surface of these devices.

[0139] Specifically, the embodiments of the present application can perform whole-board coating on the electronic components such as circuit boards provided with connectors, i.e., forming a hydrophobic coating on the entire surface of the circuit board (including the surface of the contacts of the connectors). As mentioned above, the hydrophobic coating is easy to be pierced or pushed away by the terminals of the connectors, and will not affect the plug-in connection of the connectors of the circuit board with other connectors, i.e., will not affect the electrical connection between the two connectors. At the same time, the hydrophobic coating has good flexibility, and will not damage the hydrophobic coating of other parts during the plug-in process of the two connectors, thereby maintaining the protection effect of the hydrophobic coating on the connectors and other devices.

[0140] ​As mentioned above, the film-forming composition of the present application can be applied on the surface of the device by a process such as dot coating (jet dot coating), spray coating (atomized spray coating), curtain coating (curtain coating), dip coating, brush coating, etc., and solidified into a film on the surface of the device to form a protective coating. In the application process, the film-forming composition can be applied by a single coating process (i.e. one-time application) or by a multi-coating process. For example, the film-forming composition can be used to protect the entire circuit board assembly, and the atomized spray process (atomized spray coating process) can be used to spray the film-forming composition on the surface of the entire circuit board assembly, and the hydrophobic coating can be formed by multiple spray coating to avoid the problem of local defects in the coating formed by a single coating process.

[0141] When applied by a multi-coating process, the thickness of the film layer formed after each coating (single-coating coating thickness) can be 5 μm to 50 μm, and after multiple coatings, a hydrophobic coating with a final thickness of 10 μm to 100 μm can be formed. Relatively speaking, if the single-coating coating thickness is too thin (< 5 μm), the probability of local defects (such as local coating being too thin, or even exposing the device surface) is relatively high, and if the single-coating coating thickness is too thick, the surface smoothness of the formed hydrophobic coating is poor (for example, uneven and inconsistent appearance such as orange peel phenomenon is prone to occur), although the coating surface will become smooth after a period of time, but the processing efficiency will be affected.

[0142] Generally, due to factors such as spray angle and flowability of the film-forming composition during spraying, the coating thickness on the surface plane of the substrate will be higher than the coating thickness on the corner structure (such as 3D pin) of the electronic component disposed on the substrate. However, by using the film-forming composition of the present application, a higher coating thickness on the corner structure can be achieved at the same plane coating thickness.

[0143] In addition, for the corner position such as the 3D pin of the electronic component, the film-forming composition can be applied by a dot coating process, which is beneficial to further improve the coating thickness and uniformity of the surface of the corner position, and avoid the problem of too thin local coating thickness due to the influence of factors such as spray angle.

[0144] In addition, when the thickness of the hydrophobic coating on the connector contact surface is too large, it does not affect the electrical conduction of the connector substantially even after a few insertions and extractions, but it can cause a certain fluctuation in the conduction resistance of the connector after multiple insertions and extractions. Therefore, to further avoid the influence on the electrical conductivity of the connector, the thickness of the hydrophobic coating is preferably not greater than 100 μm. In a specific implementation, after forming the hydrophobic coating on the circuit board and other components, a long-term salt spray corrosion test (for example, a salt spray test using a 5% neutral sodium chloride aqueous solution for 500-1000 hours) and other performance test experiments in the art can be performed to make the thickness and other parameters of the hydrophobic coating meet the test requirements (for example, the circuit board component has no functional abnormalities within a few days of being immersed in water and powered on, the circuit board has no functional abnormalities within a few tens of days of being sprayed with water and powered on, etc.). Thus, the coating thickness of the film-forming composition can be controlled in combination with the above factors to form a hydrophobic coating with a predetermined thickness.

[0145] In the embodiments of the present application, the hydrophobic coating on the structural member can be redissolved when it encounters solvent C (such as a non-polar solvent). Therefore, when the above structural member needs to be repaired or processed, solvent C (such as a non-polar solvent) can be used to dissolve the hydrophobic coating. Thus, the embodiments of the present application also have the advantages of easy removal of the hydrophobic coating and good reworkability of the structural member, which are beneficial to practical application.

[0146] In the embodiments of the present application, when the hydrophobic coating is scratched by mechanical external force, if the scratched part is damaged, the damaged position can be repaired by spot coating with the film-forming composition.

[0147] In the embodiments of the present application, the hydrophobic coating is mainly physically blended from polymer A and polymer B. At high temperature (such as welding temperature (> 200℃)), the hydrophobic coating can be softened, and high-density molten solder can enter below the hydrophobic coating and be welded between the solder pad and other structures located below the hydrophobic coating. Therefore, even if such a hydrophobic coating is applied to the surface of the circuit board, it still has good reworkability.

[0148] In some embodiments, as shown in Figure 1 The structural member includes a substrate 1 and electronic components disposed on the substrate. The electronic components are chip electronic components (chip components) 21 and wing-shaped pin devices. The chip electronic components 21 and the wing-shaped pin devices are arranged at intervals. One side of the substrate 1 on which the electronic components are disposed includes a third planar region 10, which is a region of the surface of the substrate 1 on which no electronic components are disposed. The chip electronic components 21 have two solder end pins (3D pins) 211 on the side facing away from the substrate. The solder end pins 211 have a corner structure (such as Figure 1The two solder end pins are arranged at intervals, and the side of the chip electronic component 21 facing away from the substrate includes a first plane area 210 located between the two solder end pins 211. The wing pin device includes a body 22 and a wing pin (3D pin) 221. The wing pin 221 is connected between the body 22 and the substrate 1. The bending parts of the body 22 and the wing pin 221 both have corner structures (such as Figure 1 The side of the body 22 facing away from the substrate 1 includes a second planar region 220. The hydrophobic coating 3 is continuously formed on the entire surface of the side of the structural member where the electronic components are provided (the hydrophobic coating is uninterrupted). That is, the hydrophobic coating 3 covers the surface of the substrate where no electronic components are provided (the third planar region 10), and also covers the surfaces of the chip-type electronic components and the devices with special-shaped leads. Figure 1 Area A in the figure only indicates the corner structure of a part of the structural member, and the corner structures of other areas of the structural member are not indicated.

[0149] In other embodiments, Figure 2 As shown, the structural member includes a substrate and an electronic component arranged on the substrate. The electronic component is a display screen module, which includes a polarizer 101, an optical adhesive layer (OCA adhesive layer) 102, a display panel (screen body) 103, and a cover glass 104 stacked in sequence.

[0150] Among them, optical film materials such as OCA adhesive layer 102 and polarizer 101 are sensitive to external pollution. For example, these optical materials are easily corroded when they encounter external polluting liquids such as sweat, which in turn causes the display module to fail. The hydrophobic coating 3 is provided on the surface of these film materials, for example, Figure 2 As shown, a hydrophobic coating 3 is provided on the side edge of the screen (on the side of the film materials such as the polarizer 101, the optical adhesive layer 102 and the display panel 103 (the side is parallel to the thickness direction of the film materials)), which can protect the surface of these film materials and avoid problems such as functional abnormalities and failures.

[0151] Specifically, in Figure 2 In the embodiment shown, a hydrophobic coating can be formed by a spraying process, and its thickness is, for example, 30 μm to 60 μm. Specifically, this thickness can be achieved by multiple spraying layers. During the spraying process, the screen display area can be shielded by a shielding tool to avoid spraying into the screen display area and affecting the screen display appearance.

[0152] An embodiment of the present invention further provides a terminal product, comprising the above-mentioned structural component.

[0153] Specifically, the terminal product can be an electronic device, which can be a consumer electronic device (consumer smart device), such as a smart phone, a smart watch, a smart door lock, a smart tablet, a PC, a home network terminal, an IoT smart device, etc., or a communication electronic device, such as an access layer network device, a wireless communication base station, an access network device, etc., or an industrial electronic device, such as a power supply, a controller, and a transformer, etc. devices related to high voltage operation.

[0154] In the embodiment of the present application, the hydrophobic coating layer is formed on the surface of the components such as circuit boards by using the film-forming composition, which can improve the protection effect of the components such as circuit boards in the terminal product. When the terminal product encounters water or the like, the problems such as rapid short circuit, corrosion failure of the components such as circuit boards caused by water, and corrosion failure of the components such as circuit boards caused by dampness, etc. are not easy to occur, thereby the application reliability of the terminal product can be significantly improved.

[0155] The present application is further described below through specific examples.

[0156] In the following examples and comparative examples, the methyl silicone resin (polydimethylsiloxane with cross-linked structure) is a solid polymer, and the water drop angle thereof is about 102-104°; the linear dimethyl polysiloxane is a liquid polymer, and the water drop angle thereof is about 100°, and the viscosity thereof is about 200,000 mPa·S.

[0157] In the following examples and comparative examples, the coating thickness (hydrophobic coating thickness) refers to the average thickness, unless otherwise specified.

[0158] Example 1

[0159] The film-forming composition of this example 1 is a mixture of dimethyl silicone resin (polymer A), linear dimethyl polysiloxane (polymer B) and n-decane (solvent C), and the mass ratio of dimethyl silicone resin, linear dimethyl polysiloxane and n-decane is 20:5:75, and the viscosity of the film-forming composition is about 5 mPa·S.

[0160] The above film-forming composition is used to spray the entire circuit board which has been assembled with BTB connector, 0402 chip resistor, 0201 chip capacitor, SOP packaged device, etc. by atomization spraying process, the coating thickness of the first spraying is 20 μm, and then the second spraying is performed on the coating formed by the first spraying, and the coating thickness of the second spraying is 20 μm; wherein, the pins of the SOP packaged device (SOP pins) and the pin area of the connector are spot coated to ensure that the protective coating of the 3D pins of the device is well wrapped.

[0161] Example 2: The difference from Example 1 is that the mass ratio of dimethyl silicone resin, linear dimethyl polysiloxane, n-decane in the film-forming composition of Example 2 is 50:15:35, the viscosity of the film-forming composition is about 100 mPa-S or so, and the rest of the conditions are the same as those of Example 1.

[0162] Example 3: The difference from Example 1 is that the mass ratio of dimethyl silicone resin, linear dimethyl polysiloxane, n-decane in the film-forming composition of Example 6 is 30:5:65, the viscosity of the film-forming composition is about 10 mPa-S or so, and the rest of the conditions are the same as those of Example 1.

[0163] Comparative Example 1: No hydrophobic coating is provided on the structural member.

[0164] Comparative Example 2: The difference from Example 1 is that the alcohol acid resin type three-proofing paint is used to replace the film-forming composition, that is, the conventional alcohol acid resin type three-proofing paint is used to spray the entire circuit board which has been assembled with BTB connector, 0402 chip resistor, 0201 chip capacitor, SOP packaged device and other devices, and when spraying, the BTB connector is shielded to avoid the formation of a hydrophobic coating on the surface of the BTB device; the rest of the conditions are the same as those of Example 1.

[0165] Comparative Example 3: The difference from Example 1 is that the film-forming composition of Comparative Example 3 is a mixture of linear dimethyl polysiloxane and n-decane solvent mixed in a mass ratio of 20:80, and the rest of the conditions are the same as those of Example 1.

[0166] The structural member with a hydrophobic coating formed in each example and comparative example is tested as follows, and the results are shown in Table 1.

[0167] 1. Hydrophobicity: Test the water droplet angle of the hydrophobic coating.

[0168] 2. Slice the hydrophobic coating, and use a high-power microscope (magnification about 200 times) to detect the cross section formed, and it is measured that the hydrophobic coating in Examples 1-3 includes a film matrix and particles dispersed in the film matrix (the area ratio of the particles is less than 10%), the film matrix is physically mixed by polymer A and polymer B, the particles are formed by polymer A, and the average size of the particles is about 2-5 μm or so.

[0169] 3. Circuit board surface coating thickness H 平面 : Slice the coating on the surface of the circuit board (the hydrophobic coating of the planar area), and measure its thickness to measure the thickness of the coating on the surface of the circuit board.

[0170] 4. SOP pin surface coating thickness H sop: The coating on the surface of the SOP pin (the coating on the corner structure surface) is sliced and its thickness is measured to measure the thickness of the coating on the surface of the SOP pin.

[0171] 5. The thickness H of the coating at the tip corner of the solder end of the chip component 尖角 : The coating at the tip corner of the solder end of the chip component (the coating on the corner structure surface) is sliced and its thickness is measured to measure the thickness H of the coating at the tip corner of the solder end of the chip component 尖角 .

[0172] 6. The connector conductivity: the contact resistance R between the terminals of the connector is tested by using a four-wire method.

[0173] 7. The protection performance of the circuit board: the structural member (the circuit board with the hydrophobic coating formed on the surface) is immersed in distilled water as a whole, the current change in the process of power-on is observed, and the time t when the current reaches 1 mA is recorded.

[0174] Table 1

[0175] Test item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Water drop angle 104° 102° 106° / 85° 99° H 平面 ]] 40 μm 40 μm 40 μm / 40 um 40 μm H sop ]]> 9 μm 25 μm 13 μm / <1 μm 2-4 μm H 尖角 ]] 10 μm 23 μm 15 μm / <1 μm 3-5 μm Resistance R < 15 mΩ < 15 mΩ < 15 mΩ / / <15 mΩ Time t > 60 min > 600 min > 120 min <1 min <1 min <20 min

[0176] It can be seen that, relative to Comparative Examples 1-3, the hydrophobicity of Examples 1-3 is better, and the protection effect on the circuit board is better (the time t when the current reaches 1 mA is > 60 min).

[0177] In addition, relative to Comparative Examples 1-3, the thickness (H sop of the hydrophobic coating at the corner position (such as the tip corner of the solder end of the chip component, the surface of the SOP pin, etc.) of Examples 1-3 can be significantly improved (H 尖角 ≥ 9 μm, H ≥ 10 μm), which indicates that the film-forming composition of Examples 1-3 can avoid the corner effect and significantly improve the protection effect on the circuit board and other structural members as a whole.

[0178] In addition, the hydrophobic coating in Examples 1-3 can be formed on the contact surface of the BTB connector, and does not affect the electrical connection (the resistance R < 15 mΩ) between the connector and other connectors.

[0179] Therefore, it is proved that the film-forming composition of the examples of the present application has good hydrophobicity, can avoid the corner effect, effectively improve the thickness of the hydrophobic coating formed at the corner position, and the hydrophobic coating formed from the film-forming composition has good flexibility and other properties, which can be formed on the surface of the BTB connector and other devices, and the hydrophobic coating on the contact surface of the connector is easily pierced or pushed away by the connecting terminals of the connector when being pressed by two matched connectors, so as to realize the electrical connection between the two connectors, and at the same time, the hydrophobic coating at other positions will not be damaged in the process of plugging the two connectors, so as to maintain the protection effect of the hydrophobic coating on the connector and other devices.

[0180] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A film-forming composition, characterized by, The film-forming composition comprises the following components A-C: A, a hydrophobic polymer I, the hydrophobic polymer I being a solid polymer, the solid polymer comprising a solid polymer in a cross-linked molecular structure; B, a hydrophobic polymer II, the hydrophobic polymer II being a liquid polymer; C, an organic solvent; The sum of the mass fractions of the hydrophobic polymer I and the hydrophobic polymer II is greater than or equal to 20% based on the total mass of the film-forming composition; The mixing ratio of the hydrophobic polymer I in the hydrophobic polymer II is greater than the solubility of the hydrophobic polymer I in the hydrophobic polymer II; After the organic solvent volatilizes, part of the hydrophobic polymer I dissolves in the hydrophobic polymer II and physically mixes with the hydrophobic polymer II to form a film matrix, and another part of the hydrophobic polymer I precipitates to form particulate matter in the volatilization process of the organic solvent, and the particulate matter is dispersed in the film matrix.

2. The film-forming composition according to claim 1, characterized in that, The water drop angle of the hydrophobic polymer II is greater than or equal to 90 degrees.

3. The film-forming composition according to claim 1 or 2, characterized in that, The viscosity of the hydrophobic polymer II is greater than or equal to 10,000 mPa·S.

4. The film-forming composition of claim 1, wherein The hydrophobic polymer II comprises silicone oil and / or linear polyolefin.

5. The film-forming composition of claim 1, wherein The water drop angle of the hydrophobic polymer I is greater than or equal to 90 degrees.

6. The film-forming composition according to claim 1 or 5, characterized in that, The hydrophobic polymer I comprises one or more of silicone resin, polyolefin, and fluorinated polymer.

7. The film-forming composition of claim 1, wherein The hydrophobic polymer I and the hydrophobic polymer II are of the same material.

8. The film-forming composition according to claim 7, wherein The hydrophobic polymer I and the hydrophobic polymer II belong to a silicone system or a polyolefin system.

9. A structural member, characterized by The structure comprises: A substrate; An electronic component disposed on the substrate; A hydrophobic coating layer on the side of the substrate provided with the electronic component and present on the surface of the electronic component, the hydrophobic coating layer being formed by the film-forming composition according to any one of claims 1-8; The hydrophobic polymer I is a solid polymer, the solid polymer comprising a solid polymer in a cross-linked molecular structure, and the hydrophobic polymer II is a film-forming polymer.

10. The structural member of claim 9, wherein The water drop angle of the hydrophobic coating layer is greater than or equal to 90 degrees.

11. The structural member of claim 9, wherein The electronic component has a corner structure, the hydrophobic coating layer covers the corner structure, and the thickness of the hydrophobic coating layer covering the corner structure is greater than 5 μm.

12. The structural member of claim 9, wherein The electronic component and / or the substrate have a planar region, the hydrophobic coating layer covers the planar region, and the thickness of the hydrophobic coating layer covering the planar region is 10 μm-100 μm.

13. The structural member of claim 9, wherein The electronic component comprises a pin, and the surface of the pin is provided with the hydrophobic coating layer.

14. The structural member of any of claims 9-13, wherein, The electronic component comprises a connector, and the surface of the connector is provided with the hydrophobic coating layer.

15. The structural member of any of claims 9-13, wherein, The substrate is provided with a plurality of electronic components, and the hydrophobic coating layer is continuously distributed between and covers at least two adjacent electronic components.

16. A terminal product, characterized in that The structure comprises the structure according to any one of claims 9-15.

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