Preparation method of thin coating type protective glue, thin coating type protective glue and protective film

Abstract

The invention discloses a preparation method of a thin coating type protective adhesive, the thin coating type protective adhesive and a protective film. The preparation method comprises the following steps: (1) pre-dispersing 0.1-1 part by mass of nano fumed silica, 0.1-0.5 part by mass of a fluorescent whitening agent and 50-80 parts by mass of solvent oil; and (2) sequentially adding 0.01 to 0.04 part by mass of a platinum catalyst, 2 to 7 parts by mass of vinyl-polyhedral oligomeric silsesquioxane and 20 to 50 parts by mass of hydrogen-terminated silicone oil. According to the scheme, the ultrathin coating can be formed while the surfaces, corners, curved surfaces and welding spots of components are completely covered, and the hydrophobic performance, the insulating performance, the environmental protection performance and the safety performance of the coating are effectively ensured.

Description

Technical Field

[0001] The present invention relates to the field of protective adhesives, and in particular to a preparation method of a thin-coat protective adhesive capable of fully covering components on an integrated circuit board, and to the thin-coat protective adhesive and a protective film. Background Art

[0002] With the advancement of miniaturization and high-density integration in electronic devices, protective coatings for integrated circuit board components must be ultra-thin, highly reliable, and environmentally adaptable. Existing conductive parts of integrated circuit board components, such as terminal electrodes, leads, and solder joints, are susceptible to environmental corrosion, leading to electrical failure. This is typically caused by corrosion of metal electrodes and metal connections by moisture and oxygen in the air. Failure of these metal electrodes and metal connections ultimately leads to component / IC failure. Therefore, industry often sprays or impregnates these critical areas with protective adhesive to isolate them from air and moisture.

[0003] The existing protective adhesives for integrated circuit board components include the following:

[0004] First, epoxy resin materials: Epoxy resin has good bonding strength and dielectric properties, but due to its high cross-linking density, excessive molecular chain rigidity, large elastic modulus, and low toughness, the connection parts are prone to cracking and failure after being subjected to hot and cold shocks. Therefore, this type of material is usually only used in flat primers.

[0005] Second, polyurethane and acrylic materials: polyurethane has poor water vapor resistance and its application is narrow; although acrylic protective coating is widely used, its water vapor permeability is high.

[0006] At the same time, with the development of integrated circuits towards miniaturization and high power, materials also need to be ultra-thin. Traditional protective adhesives are often applied by dipping, spraying and curing to form coatings that are over 60μm thick. To meet the requirements for thin coatings, the following improvements have been made in existing technologies:

[0007] A Chinese invention patent with publication number CN103640304A discloses a fuselage shell with a fluorocarbon protective layer. The protective coating includes a layer of zinc yellow acrylic polyurethane primer and two layers of fluorocarbon topcoat. The coating thickness can reach about 45μm, but fluorine-containing materials are not friendly to humans and the environment. In addition, some fluorocarbon coatings have a high curing temperature, which can easily cause thermal damage at the solder joints.

[0008] Chinese invention patent publication number CN118667504A discloses a high-strength silicone batch coating adhesive, its preparation method and application. The material has excellent fluidity, but because it uses terminal alkoxy-terminated moisture curing, the bottom of the coating is difficult to cure and the curing time is long.

[0009] From the above prior art, the current protective glue product cannot consider the full coverage of the ultra-thin coating and the hydrophobic, mechanical properties, protection, anti-aging and other properties. SUMMARY

[0010] Therefore, to solve the above problems, the application provides a preparation method of thin-coated protective glue, thin-coated protective glue and protective film.

[0011] The application is realized by the following technical solutions:

[0012] The preparation method of the thin-coated protective glue comprises the following steps:

[0013] (1) The nano fumed silica with a mass content of 0.1-1 parts, the fluorescent whitening agent with a mass content of 0.1-0.5 parts and the solvent oil with a mass content of 50-80 parts are pre-dispersed at a speed of 800 rpm / min-1000 rpm / min for 30-60 min to form a mixed solution;

[0014] (2) The platinum catalyst with a mass content of 0.01-0.04 parts, the vinyl-vaulted polysilsesquioxane with a mass content of 2-7 parts and the end-hydrogen silicone oil with a mass content of 20-50 parts are sequentially added to the mixed solution, and stirred at a speed of 30 rpm / min-50 rpm / min for 30-60 min;

[0015] The vinyl-vaulted polysilsesquioxane is octavinyl-POSS, the CAS number of the octavinyl-POSS is 69655-76-1, the active hydrogen of the end-hydrogen silicone oil is located at both ends of the main chain, and the hydrogen content is 0.1wt%-0.12wt%, and the nano fumed silica adopts hydrophobic fumed silica.

[0016] Preferably, the solvent oil comprises one or more of carbon hydrocarbon solvent oils of types D30, D40, D60, D80, D100 and D120 and / or methylsiloxanes of types OS20 and OS30.

[0017] Preferably, the solvent oil comprises carbon hydrocarbon solvent oil and methylsiloxane, and the mass ratio of the carbon hydrocarbon solvent oil and the methylsiloxane is 7:3.

[0018] Preferably, the platinum catalyst adopts Ashby's catalyst PT5000-VMC1000.

[0019] Preferably, the nano fumed silica adopts one or more of Wacker H15, H18, H20, Evonik DeGussa R202, R972, R974, Cabot TS-720 and TS610.

[0020] Preferably, the fluorescent whitening agent is 2.5-bis-(5-tert-butyl-2-benzoxazolyl)thiophene.

[0021] The thin coating protective adhesive is prepared by the method for preparing thin coating protective adhesive.

[0022] The protective film is suitable for the surface of components of an integrated circuit board, and has a thickness of 1-30 microns, and comprises, by mass fraction: 0.1-1 part of nano fumed silica, 0.1-0.5 part of fluorescent whitening agent, 50-80 parts of solvent oil, 0.01-0.04 part of platinum catalyst, 2-7 parts of octavinyl-POSS, and 20-50 parts of hydrogen-terminated silicone oil, wherein the hydrogen content of the hydrogen-terminated silicone oil is 0.1-0.12 wt%.

[0023] The beneficial effects of the technical scheme of the present application mainly include:

[0024] 1. The cage-shaped siloxane skeleton of octavinyl-POSS and the hydrogen-terminated silicone oil undergo a hydrosilylation reaction under the catalysis of platinum, and after curing, a block copolymer of vinyl-POSS (rigid segment) + polydimethylsiloxane (flexible segment) is formed, the active hydrogen of the hydrogen-terminated silicone oil is located at both ends of the main chain, forming a chain extension or slightly crosslinked structure, so the crosslinking network density is lower, the molecular chain activity is higher, thereby giving the cured adhesive better flexibility, elasticity and lower curing shrinkage stress, which is conducive to stress release during high and low temperature impact, improving the failure of protective performance caused by cracking and bulging of the coating body / coating and the substrate caused by temperature impact, and at the same time, the hydrogen-terminated silicone oil and vinyl-POSS can form chain crosslinking and curing, which is convenient for better control of the thickness of the coating, and at the same time of realizing full coverage of the components, an ultrathin coating is formed.

[0025] 2. The nano fumed silica as a high-efficiency nanoscale reinforcing filler can fill the network gap of the cage-shaped space structure of octavinyl-POSS, thereby forming a dense stack, making the coating form a super-hydrophobic surface, the nano fumed silica adopts a hydrophobic fumed silica after surface treatment, which can further enhance the hydrophobic performance of the coating and reduce the water vapor transmission rate, and at the same time, the nano fumed silica and the silicone matrix form a strong interaction, greatly improving the tensile strength, modulus, tear strength and wear resistance of the coating, in addition, the nano fumed silica can improve the rheological properties of the coating and prevent sagging during construction.

[0026] 3. A stable and good performance delayed platinum catalyst is selected, which is based on a complex of chloroplatinic acid and a vinyl ring, and exhibits high reactivity and excellent anti-yellowing performance, and has excellent storage stability, and at the same time, due to the small and controllable number of active hydrogen sites of the hydrogen-terminated silicone oil, the reaction and curing speed can be controlled to realize high fluidity of the product, thereby ensuring the thin coating coating requirement.

[0027] 4. Select a specific ratio of hydrocarbon solvent oil and methyl silicone as the solvent oil. This type of solvent oil has good miscibility with materials such as vinyl-POSS, hydrogenated silicone oil, and hydrophobic gas silicone. After mixing, it can form a uniform colloid and evaporate quickly, ensuring a smooth and uniform protective coating after application, avoiding undesirable appearance defects such as wrinkles and orange peel. It also improves the density of the protective coating and reduces water vapor transmission. In addition, hydrocarbon solvent oil and methyl silicone are non-aromatic hydrocarbon solvents and are less toxic to the human body.

[0028] 5. In the preparation method, granular materials such as nano-fumed silica and fluorescent whitening agent are first pre-mixed and dispersed with solvent oil to effectively break up the agglomeration, and then the platinum catalyst, vinyl-POSS and hydrogen-terminated silicone oil are added to carry out addition reaction. On the one hand, it avoids the increase in viscosity caused by pre-polymerization and affects the coating thickness. On the other hand, it can improve the high dispersibility of nano-fumed silica and fluorescent whitening agent in the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a metallographic microscope image of the protective film of the present invention solidified on the surface of the substrate;

[0030] Figure 2 This is a schematic diagram of the working state in Example 3 of the present invention in which the corners / curved surfaces of the integrated circuit board are sliced ​​and then observed with a metallographic microscope and points are selected for measurement. DETAILED DESCRIPTION

[0031] In order to more clearly and in detail illustrate the objects, advantages and features of the present invention, the following non-limiting description of preferred embodiments will be used for illustration and explanation. This embodiment is merely a typical example of the application of the technical solution of the present invention. Any technical solution formed by equivalent substitution or equivalent transformation falls within the scope of protection claimed by the present invention. Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0032] The present invention discloses a method for preparing a thin-coat protective adhesive, which is particularly applicable to full coverage protection of integrated circuit board components. The preparation method comprises the following steps:

[0033] (1) pre-dispersing 0.1-1 parts by weight of nano-fumed silica, 0.1-0.5 parts by weight of a fluorescent whitening agent, and 50-80 parts by weight of solvent oil at a speed of 800-1000 rpm / min for 30-60 minutes to form a mixed solution;

[0034] (2) adding platinum catalyst with a mass content of 0.01-0.04 parts, octenyl-cage polysilsesquioxane with a mass content of 2-7 parts and end-hydrogen silicone oil with a mass content of 20-50 parts into the mixed solution in sequence, and stirring at a speed of 30-50 rpm / min for 30-60 min;

[0035] Since the fumed silica has extremely high specific surface area and surface energy, it is extremely easy to agglomerate into hard agglomerates that are difficult to open. In step (1), the nano-fumed silica and particulate materials such as fluorescent whitening agent are fully pre-mixed and dispersed with solvent oil, effectively breaking the agglomeration, so that the nano-fumed silica and fluorescent whitening agent are uniformly and stably dispersed in the solvent oil. If the platinum catalyst, octenyl-cage polysilsesquioxane and end-hydrogen silicone oil are added first, then a high-viscosity prepolymer will be formed after the addition reaction, and the subsequent addition of nano-fumed silica and fluorescent whitening agent will easily lead to local agglomeration, affecting the mechanical properties and stability of the colloid.

[0036] The octenyl-cage polysilsesquioxane has a chemical molecular formula as follows:

[0037]

[0038] The end-hydrogen silicone oil has active hydrogen at both ends of the main chain, and the hydrogen content is 0.1wt%-0.12wt%. The end-hydrogen silicone oil has a chemical molecular formula as follows:

[0039]

[0040] As can be seen from the chemical molecular formula of the end-hydrogen silicone oil, the end-hydrogen silicone oil usually has only two reactive sites at the ends of one molecule. When it reacts with octenyl-POSS, it mainly forms a chain-extended or lightly crosslinked structure, i.e. the linear end-hydrogen silicone oil molecule is "connected" to multiple arms of the POSS. Compared with side-hydrogen or side-end-hydrogen silicone oil, the crosslinked network density formed by the end-hydrogen silicone oil and octenyl-POSS is lower, so the colloid has better flexibility, elasticity and lower curing shrinkage stress. At the same time, the colloid ensures full coverage of the surface of the component while having an extremely thin coating thickness.

[0041] The nano-fumed silica adopts hydrophobic fumed silica. The hydrophobic fumed silica has undergone surface hydrophobic treatment, which can enhance the surface hydrophobicity of the coating, reduce the water vapor transmission rate and improve the moisture resistance of the protective coating. In some preferred embodiments, the nano-fumed silica adopts one or more of Wacker H15, H18, H20, Evonik DeGussa R202, R972, R974, Cabot TS-720 and TS610.

[0042] In some embodiments, the solvent oil comprises one or more of hydrocarbon solvent oil of model D30, D40, D60, D80, D100, D120 and / or methylsilicone of model OS20, OS30; in some preferred embodiments, the solvent oil comprises hydrocarbon solvent oil and methylsilicone, and the mass ratio of the hydrocarbon solvent oil and methylsilicone is 7:3; the hydrocarbon solvent oil and methylsilicone are well miscible with vinyl-POSS, hydrogen-containing silicone oil, hydrophobic aerogel, etc., and can form a uniform colloid after mixing, so as to ensure that a smooth and uniform protective coating is formed after the coating is applied. Meanwhile, the above-mentioned solvent oils are non-aromatic hydrocarbon solvents, which are less toxic to human body.

[0043] In some preferred embodiments, the platinum catalyst is Ashby's catalyst PT5000-VMC1000. The delayed platinum Ashby's catalyst is based on a complex of chloroplatinic acid and a vinyl ring body, and has excellent stability.

[0044] In some preferred embodiments, the fluorescent whitening agent is 2.5-bis-(5-tert-butyl-2-benzoxazolyl) thiophene.

[0045] The application also discloses a thin-coating protective glue prepared by the above-mentioned preparation method of thin-coating protective glue. According to the preparation method of the thin-coating protective glue, the raw materials in the preparation method are used to obtain the thin-coating protective glue of the following embodiments 1-8. Meanwhile, the raw materials or the ratio of the raw materials different from the above-mentioned preparation method are used to obtain the protective glue of the following comparative examples 1-5. The raw materials of each embodiment and comparative example are shown in Table 1.

[0046] Table 1: Raw materials and ratios used in embodiments 1-8 and comparative examples 1-5;

[0047]

[0048] The protective glue of the above-mentioned embodiments 1-8 and comparative examples 1-5 is respectively sprayed / immersed on an integrated circuit board and components thereof, and is cured at room temperature for 1 hour / 120°C for 5 minutes, so as to form a protective coating on the surface of the integrated circuit board and components thereof.

[0049] Subsequently, the protective coating of each embodiment and comparative example after curing is tested in the following aspects:

[0050] 1. Coating thickness test:

[0051] For the plane surface of the integrated circuit board and its components, the existing interferometer equipment is used to measure through laser interferometry. The phase change of the light wave caused by the optical path difference is used to produce interference fringes of alternating light and dark. The interference fringes are then measured and combined with the refractive index to calculate the coating thickness.

[0052] For the corner / curved surface, slice the corner / curved surface and observe it with a metallographic microscope. Select multiple points at equal intervals to measure the coating thickness, and then select the average value as the current measurement data, as shown in the attached figure. Figure 2 The figure shows a schematic diagram of metallographic microscope observation of the corner section of Example 3 after slicing;

[0053] 2. Water vapor transmission performance test: GB / T 1037-2023 standard is used for testing;

[0054] 3. Water absorption test: GBT 1034-2008 standard is used for testing;

[0055] 4. High and low temperature impact test: Place the product in a low temperature environment of -50℃ for 30 minutes, then raise the ambient temperature to 150℃ for 30 minutes. This is a hot and cold cycle. After 1000 hot and cold cycles, the water absorption rate of the product is tested using the GBT 1034-2008 standard.

[0056] 5. High temperature and high humidity resistance test: After being placed in a test environment with an ambient temperature of 85°C and an ambient humidity of 85% for 1000 hours, the water absorption rate of the product is tested using the GBT 1034-2008 standard;

[0057] 6. Insulation strength: tested in accordance with GB / T 1408.1-2016 standard;

[0058] The test results are shown in Table 2 below:

[0059] Table 2: Test results of Examples 1-8 and Comparative Examples 1-5;

[0060]

[0061] According to Table 2 above:

[0062] Compared with Example 2, Reference Example 1 adopts common vinyl silicone oil to replace vinyl-POSS, and the other raw materials and proportions are unchanged. As can be seen from Table 2 above, the insulation performance of Reference Example 1 is worse than that of the coating of Example 2, and its water vapor transmission rate and water absorption rate are both higher, and its hydrophobicity decreases.

[0063] Compared with Example 2, Control Example 2 does not add a platinum catalyst, which results in the inability of vinyl-POSS and hydrogen-terminated silicone oil to effectively crosslink and cure, high water absorption, and poor resistance to temperature shock, high temperature and high humidity.

[0064] Compared with Example 2, the solvent content in Control Example 3 is less, and the dispersibility of each material is reduced, resulting in a thicker coating thickness after curing.

[0065] Compared with Example 2, Control Example 4 uses ordinary gas silica without surface treatment to replace the hydrophobic gas silica, and the water absorption rate and water vapor permeability are higher, and the hydrophobic performance is reduced.

[0066] Compared with Example 2, Control Example 5 uses side hydrogen / side end hydrogen silicone oil instead of end hydrogen silicone oil, so the crosslinking density is increased, resulting in a thicker coating thickness of more than 30um after curing. In addition, the high and low temperature impact resistance is reduced, and the water absorption rate after high and low temperature impact increases to 0.06%.

[0067] The content of end-hydrogen silicone oil in Example 1, Example 2 and Example 3 gradually increases, but as the content of end-hydrogen silicone oil increases, the water absorption rate, water vapor permeability and high temperature and humidity resistance of the coating decrease. Therefore, the content of end-hydrogen silicone oil should be limited to a reasonable range of this scheme.

[0068] In Example 4, the vinyl-POSS content is reduced compared with Example 1. Although the overall coating thickness is attenuated, its hydrophobicity is also significantly reduced. On the contrary, when Example 5 is compared with Example 3, it is known that when the vinyl-POSS content is significantly increased, the overall coating thickness also increases therewith.

[0069] Compared with Example 2, Example 6 has an increased platinum catalyst content, which instead leads to a decrease in insulation strength. This is because an excessive amount of platinum catalyst may not be completely consumed or removed after the reaction, and may remain in the solidified colloid in the form of free platinum nanoparticles or platinum complexes, thereby forming a local conductive channel and reducing the volume resistivity.

[0070] Comparing Example 2 and Example 8 with Example 7, as the hydrophobic silica content increases, the water vapor transmission rate and water absorption rate both decrease, the hydrophobic performance is enhanced, but the coating thickness increases.

[0071] The present invention also discloses a protective film suitable for the surface of components of an integrated circuit board, with a thickness of 1 μm to 30 μm. The components thereof, in parts by mass, include: 0.1 to 1 part of nano-fumed silica, 0.1 to 0.5 parts of a fluorescent brightener, 50 to 80 parts of solvent oil, 0.01 to 0.04 parts of a platinum catalyst, 2 to 7 parts of octaethylene-POSS, and 20 to 50 parts of hydrogen-terminated silicone oil, wherein the hydrogen content of the hydrogen-terminated silicone oil is 0.1 wt% to 0.12 wt%. The protective film can be formed by curing the thin-coat protective adhesive, wherein the thin-coat protective adhesive is sprayed or impregnated on the surface of a substrate and then cured, and the curing method is room temperature curing for 1 hour or 120°C curing for 5 minutes. After curing, a protective film is formed on the surface of the substrate, such as Figure 1 The figure shows a metallographic microscope image of a protective film covering the surface of a substrate.

[0072] There are many implementation methods of the present invention, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for preparing a thin-coat protective adhesive, characterized in that: The following steps are involved: (1) pre-dispersing 0.1-1 parts by weight of nano-fumed silica, 0.1-0.5 parts by weight of a fluorescent whitening agent, and 50-80 parts by weight of solvent oil at a speed of 800-1000 rpm / min for 30-60 minutes to form a mixed solution; (2) adding 0.01-0.04 parts by weight of a platinum catalyst, 2-7 parts by weight of a vinyl-cage polysilsesquioxane, and 20-50 parts by weight of a hydrogen-terminated silicone oil to the mixed solution, and stirring at a speed of 30-50 rpm / min for 30-60 min; The vinyl-cage polysilsesquioxane is octavinyl-POSS, and the CAS number of the octavinyl-POSS is 69655-76-1. The active hydrogen of the hydrogen-terminated silicone oil is located at both ends of the main chain, and the hydrogen content is 0.1wt%-0.12wt%. The nano-fumed silica adopts hydrophobic gas silica.

2. The method for preparing a thin-coat protective adhesive according to claim 1, characterized in that: The solvent oil includes one or more of hydrocarbon solvent oils with models D30, D40, D60, D80, D100, and D120 and / or methylsiloxanes with models OS20 and OS30.

3. The method for preparing the thin-coat protective adhesive according to claim 2, characterized in that: The solvent oil includes hydrocarbon solvent oil and methyl silicone, and the mass ratio of the hydrocarbon solvent oil to methyl silicone is 7:

3.

4. The method for preparing a thin-coat protective adhesive according to claim 1, characterized in that: The platinum catalyst is Ashby's catalyst PT5000-VMC1000.

5. The method for preparing a thin-coat protective adhesive according to claim 1, characterized in that: The nano-fumed silica is one or more of Wacker H15, H18, H20, Evonik Degussa R202, R972, R974, Cabot TS-720, and TS610.

6. The method for preparing a thin-coat protective adhesive according to claim 1, characterized in that: The fluorescent whitening agent is 2.5-bis-(5-tert-butyl-2-benzoxazolyl)thiophene.

7. Thin coating protective adhesive, characterized by: The thin-coat protective adhesive is prepared by the preparation method of any one of claims 1 to 6.

8. Protective film, characterized by: Suitable for the surface of components of integrated circuit boards, with a thickness of 1µm-30µm, its components, by weight, include: 0.1-1 part of nano-fumed silica, 0.1-0.5 part of fluorescent brightener, 50-80 parts of solvent oil, 0.01-0.04 part of platinum catalyst, 2-7 parts of octaethylene-POSS and 20-50 parts of hydrogen-terminated silicone oil, wherein the hydrogen content of the hydrogen-terminated silicone oil is 0.1wt%-0.12wt%.

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