Photocuring composition, protective glue and circuit board protection method

Abstract

The invention discloses a photocuring composition, protective glue and a circuit board protection method. The photocuring composition comprises the following components in percentage by weight: 50%-70% of photocuring acrylate resin, 15%-25% of a (methyl) acrylic reactive diluent, 5%-15% of a thermosensitive debonding agent, 0.5%-5% of an additive, 3%-7% of a photoinitiator and 10%-50% of a solvent. According to the invention, the thermosensitive debonding agent is added into the photosensitive liquid composed of the light-cured acrylate resin and the (methyl) acrylic reactive diluent, and after the photosensitive liquid is cured, the thermosensitive debonding agent expands or decomposes under a heated condition to generate gas to destroy the adhesion, so that the protective glue is easy to peel off.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board processing, in particular to a photocurable composition, a protective adhesive and a circuit board protection method. Background Art

[0002] In order to protect the circuit board from the erosion of factors such as moisture, dust, chemicals and temperature changes in the environment, and to improve the durability and reliability of the circuit board, a layer of conformal coating is generally sprayed on the circuit board. Conformal coating can effectively prevent component oxidation, short circuits and other failure problems caused by the environment. However, during the spraying process, some electronic components such as connectors, switches, heat dissipation components, etc. are not suitable for coating, because conformal coating may affect their normal functions or cause heat to be unable to dissipate, so these components need to be shielded to ensure that they are not affected.

[0003] Currently, some components are mainly shielded by shielding jigs, but the production cycle of shielding jigs is long and the versatility is poor.

[0004] The above contents are only used to assist in understanding the technical solution of the invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The main purpose of the present invention is to provide a photocurable composition and a preparation method and application thereof, aiming to solve the problems of long production cycle and poor versatility of shielding fixtures.

[0006] To achieve the above object, the present invention provides a photocurable composition, which comprises the following components in weight percentage:

[0007] 50% to 70% of light-curing acrylate resin, 15% to 25% of (meth) acrylic acid active diluent, 5% to 15% of heat-sensitive debonding agent, 0.5% to 5% of additives, 3% to 7% of photoinitiator and 10% to 50% of solvent.

[0008] In one embodiment, the photocurable acrylate resin includes at least one of epoxy acrylate, polyurethane acrylate, polyester acrylate, polyether acrylate, and bis(4-acryloxyphenyl) carbonate.

[0009] In one embodiment, the (meth)acrylic reactive diluent includes at least one of isobornyl acrylate, 2-hydroxyethyl acrylate, phenoxyethyl acrylate, and propoxy tripropylene glycol acrylate.

[0010] In one embodiment, the heat-sensitive debonding agent is heat-expandable microspheres or microcapsules containing a thermally decomposable foaming agent.

[0011] In one embodiment, the foaming agent in the microcapsule containing the thermal decomposition type foaming agent is selected from at least one of azodicarbonamide, p-toluenesulfonylhydrazide or ammonium bicarbonate.

[0012] In one embodiment, the wall material of the microcapsule containing the thermal decomposition type foaming agent is polyurea, phenolic resin or melamine formaldehyde resin.

[0013] In one embodiment, it further comprises 0.5%-15% of a heat expansion filler, wherein the heat expansion filler is a hollow glass microsphere or a polymer microsphere with a particle size of 10-100 micrometers; and / or

[0014] The additive includes at least one of a thixotropic agent, a defoaming agent and a leveling agent.

[0015] In one embodiment, the photoinitiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-phenyl-1-[4-(2H-benzotriazol-2-yl)-3-tert-butylphenyl]-2-(O-methylmorpholino)propane.

[0016] The present invention also provides a protective adhesive, characterized in that the adhesive is prepared by using the above-mentioned photocurable composition.

[0017] The present invention also provides a circuit board protection method comprising the following steps:

[0018] S1: Apply the protective glue as described above on the components to be shielded on the circuit board;

[0019] S2: irradiating the circuit board with ultraviolet light or visible light at room temperature to solidify the protective glue to form a protective layer;

[0020] S3: Apply conformal coating on the circuit board;

[0021] S4: Bake the plate at 150-250°C to reduce the adhesion of the protective glue;

[0022] S5: Peel off the protective glue and conformal coating on the components to be masked.

[0023] The technical solution of the present invention is to add a thermosensitive detackifier to a photosensitive solution composed of a photocurable acrylate resin and a (meth) acrylic acid active diluent. After the photosensitive solution is cured, the thermosensitive detackifier expands or decomposes under heating conditions to generate gas to destroy adhesion, thereby making the protective adhesive easy to peel off. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that if the meaning of "and / or" appears in the full text is to include three parallel solutions, taking "A and / or B" as an example, it includes solution A, solution B, or a solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0026] "Include", "comprising", "containing", "containing", "having" or other variations herein are intended to cover non-closed inclusions, and no distinction is made between these terms. The term "comprising" means that other steps and ingredients that do not affect the final result may be added. The term "comprising" also includes the terms "mainly consisting of..." and "essentially consisting of..." The compositions and methods / processes of the present invention include, consist of, and are essentially composed of the necessary elements and restrictions described herein and any additional or optional ingredients, components, steps or restrictions described herein. All numerical values ​​or expressions used in the specification and claims involving component amounts, process conditions, etc. should be understood to be modified by "about" in all cases. All ranges involving the same component or property include endpoints, which can be independently combined. Since these ranges are continuous, they include every numerical value between the minimum and maximum values. It should also be understood that any numerical range cited in this application is intended to include all sub-ranges within the range. As used herein, "parts by weight", "parts by weight", "parts by mass" or "parts by mass" are used interchangeably, and the parts by weight may be any fixed weight expressed in milligrams, grams or kilograms (such as 1 mg, 1 g, 2 g, 5 g, or 1 kg, etc.). For example, a composition consisting of 1 part by weight of component a and 9 parts by weight of component b may be a composition consisting of 1 gram of component a + 9 grams of component b, or 10 grams of component a + 90 grams of component b, etc.

[0027] In the related art, some components are shielded by a shielding jig to prevent them from being coated with conformal coating. However, the manufacturing cycle of the shielding jig is long and its versatility is poor.

[0028] To this end, the present invention provides a photocurable composition.

[0029] In an embodiment of the present invention, the preparation materials of the photocurable composition include the following components in weight percentage: 50% to 70% photocurable acrylate resin, 15% to 25% (meth) acrylic acid reactive diluent, 5% to 15% thermosensitive debonding agent, 0.5% to 5% additives, 3% to 7% photoinitiator and 10% to 50% solvent.

[0030] The photocurable composition of the technical solution of the present invention is prepared by adding a thermosensitive detackifier to a photosensitive solution composed of a photocurable acrylate resin and a (meth) acrylic acid reactive diluent. After the photosensitive solution is cured, the thermosensitive detackifier expands or decomposes under heating conditions to generate gas that destroys adhesion, thereby making it easy to peel off the protective adhesive.

[0031] In one embodiment, the photocurable acrylate resin includes at least one of epoxy acrylate, polyurethane acrylate, polyester acrylate, polyether acrylate, and bis(4-acryloxyphenyl) carbonate.

[0032] In this embodiment, epoxy acrylate has the characteristics of high reactivity and excellent adhesion, and commercial epoxy acrylate resins such as EA-618 and EA-600 can be used. Polyurethane Acrylate: Polyurethane Acrylate: Good flexibility and high wear resistance. Good flexibility and high wear resistance, commercial products such as PUA-33 and PUA-80 can be used.

[0033] In one embodiment, the (meth)acrylic reactive diluent includes at least one of isobornyl acrylate, 2-hydroxyethyl acrylate, phenoxyethyl acrylate, and propoxy tripropylene glycol acrylate.

[0034] In this embodiment, the (meth)acrylic acid reactive diluent adopts a monofunctional acrylate monomer such as isobornyl acrylate, which can reduce viscosity, improve coating performance, and participate in the curing reaction.

[0035] In one embodiment, the thermosensitive debonding agent is a heat-expandable microsphere or a microcapsule containing a thermal decomposition type foaming agent. When heated to a set temperature, the thermosensitive debonding agent undergoes a phase change or a volume change, causing internal stress in the material and promoting debonding. Alternatively, the decomposition generates gas, generates tiny bubbles, forms interface defects, and reduces adhesion.

[0036] In this embodiment, the foaming agent is encapsulated in the polymer microcapsule, which can prevent the release of gas at room temperature. As long as the heat-sensitive debonding agent can be evenly distributed in the protective adhesive, the heat-expandable microspheres or microcapsules containing the thermal decomposition type foaming agent expand or decompose under heating conditions to produce gas to destroy the adhesion between the material and the substrate, thereby achieving the purpose of easy removal, thereby making the protective adhesive easy to peel off.

[0037] In one embodiment, the foaming agent in the microcapsule containing the thermal decomposition type foaming agent is selected from at least one of azodicarbonamide, p-toluenesulfonylhydrazide or ammonium bicarbonate.

[0038] In this embodiment, the decomposition temperature of azodicarbonamide (AC) is 170-200°C; the decomposition products are mainly nitrogen (N2), carbon monoxide (CO) and carbon dioxide (CO2), which have the characteristics of large gas release and high foaming ratio.

[0039] In this embodiment, in order to prevent AC from affecting the stability of the formula at room temperature, it is encapsulated in a polymer microcapsule and controlled to release gas only at high temperature.

[0040] In this embodiment, the core of the heat-expandable microsphere is prepared from low-boiling hydrocarbons such as pentane. The shell of the heat-expandable microsphere is prepared from thermoplastic polymer materials such as polyacrylonitrile. When the heat-expandable microsphere is heated to a certain temperature (such as 120-200° C.), the core material is gasified, and the volume of the microsphere expands rapidly, forming a multiple volume change. The expansion starting temperature can be controlled by adjusting the shell material to meet the needs of actual production.

[0041] In this embodiment, existing heat-expandable microsphere products such as Matsumoto Microsphere and Expancel (a brand of Akzo Nobel) can be purchased. According to the expansion starting temperature and expansion ratio, a suitable model can be selected, such as: Expancel 920DU series: expansion temperature of about 120-190°C, expansion ratio of 10-60 times.

[0042] When using, add the heat-expandable microspheres directly into the protective adhesive formula and stir at a low speed to prevent the microspheres from breaking until they are evenly dispersed.

[0043] In one embodiment, the wall material of the microcapsule containing the thermal decomposition type foaming agent is polyurea, phenolic resin or melamine formaldehyde resin.

[0044] In one embodiment, it further comprises 0.5%-15% of a heat expansion filler, wherein the heat expansion filler is a hollow glass microsphere or a polymer microsphere with a particle size of 10-100 micrometers; and / or

[0045] The additive includes at least one of a thixotropic agent, a defoaming agent and a leveling agent.

[0046] In this embodiment, the thermal expansion filler is a hollow glass microsphere or polymer microsphere with a particle size of 10-100 microns, which can also ensure the flatness of the coating, expand in volume when heated, generate internal stress, and promote the separation of the protective glue from the substrate. Preferably, the hollow glass microsphere produced by 3M can be used.

[0047] In this embodiment, the leveling agent may be an organic silicon leveling agent such as BYK-306 to improve the leveling property of the coating and prevent fish eyes and shrinkage cavities. The defoaming agent may be an organic silicon defoaming agent such as BYK-088 to eliminate bubbles generated during the coating process.

[0048] In one embodiment, the photoinitiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-phenyl-1-[4-(2H-benzotriazol-2-yl)-3-tert-butylphenyl]-2-(O-methylmorpholino)propane.

[0049] In one embodiment, the solvent includes an alcohol, ester, ether or ketone organic solvent, selected from one or more of isopropyl alcohol, ethyl acetate, propylene glycol methyl ether acetate, cyclohexanone, methyl ethyl ketone, butyl acetate, and xylene.

[0050] The present invention also provides a protective adhesive, characterized in that the adhesive is prepared by using the above-mentioned photocurable composition.

[0051] The present invention also provides a circuit board protection method comprising the following steps:

[0052] S1: Apply the protective glue as described above on the components to be shielded on the circuit board;

[0053] S2: irradiating the circuit board with ultraviolet light or visible light at room temperature to solidify the protective glue to form a protective layer;

[0054] S3: Apply conformal coating on the circuit board;

[0055] S4: Bake the plate at 150-250°C to reduce the adhesion of the protective glue;

[0056] S5: Peel off the protective glue and conformal coating on the components to be masked.

[0057] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art. Unless otherwise specified, the meanings of the terms in this specification are the same as those generally understood by those skilled in the art, but in case of conflict, the definitions in this specification shall prevail.

[0058] The following will be combined with specific examples to further illustrate the characteristics and applications of the photocurable composition of the present invention. It is worth noting that the following description is only exemplary and not a specific limitation of the present invention. Unless otherwise specified, the raw materials and reagents used in the examples are commercially available or prepared by known methods.

[0059] Example 1

[0060] A photocurable composition comprises, by weight, 50% of a photocurable acrylic resin, 15% of a (meth)acrylic acid active diluent, 5% of a thermosensitive debonding agent, 3% of a photoinitiator and 10% of a solvent. The thermosensitive debonding agent is a thermal expansion microsphere. The additives include 1.5% of a thixotropic agent, 0.5% of a defoaming agent and 0.3% of a leveling agent. The photoinitiator is 1-hydroxycyclohexyl phenyl ketone. The solvent is 10% of isopropanol.

[0061] Preparation method of protective film layer:

[0062] Coating: coating the photocurable composition on a substrate to form a coating on the surface of the substrate;

[0063] Exposure: UV-LED lamp with a wavelength of 365 nm or 395 nm is used as the light source for exposure, and the energy density is 800-1200 mJ / cm 2 The exposure time is 5-15 seconds, and it solidifies into a protective film layer.

[0064] Example 2

[0065] A photocurable composition comprises, by weight, 50% of a photocurable acrylic resin, 15% of a (meth)acrylic acid active diluent, 5% of a thermosensitive debonding agent, 3% of a photoinitiator and 10% of a solvent. The thermosensitive debonding agent is a microcapsule containing a thermal decomposition type foaming agent, wherein the foaming agent is azodicarbonamide, and the wall material of the microcapsule is polyurea. The additives include 1.5% of a thixotropic agent, 0.5% of a defoaming agent and 0.3% of a leveling agent. The photoinitiator is 1-hydroxycyclohexyl phenyl ketone. The solvent is 10% of isopropanol.

[0066] The method for preparing the protective film layer is the same as that in Example 1.

[0067] Example 3

[0068] A photocurable composition comprises, by weight, 50% of a photocurable acrylic resin, 15% of a (meth)acrylic acid active diluent, 10% of a thermosensitive debonding agent, 3% of a photoinitiator and 10% of a solvent. The thermosensitive debonding agent is a thermal expansion microsphere. The additives include 1.5% of a thixotropic agent, 0.5% of a defoaming agent and 0.3% of a leveling agent. The photoinitiator is 1-hydroxycyclohexyl phenyl ketone. The solvent is 10% of isopropanol.

[0069] The method for preparing the protective film layer is the same as that in Example 1.

[0070] Example 4

[0071] A photocurable composition comprises, by weight, 50% of a photocurable acrylic resin, 15% of a (meth)acrylic acid active diluent, 3% of a photoinitiator and 10% of a solvent. The heat-sensitive debonding agent comprises 5% of heat-expandable microspheres and 5% of microcapsules containing a thermal decomposition type foaming agent, wherein the foaming agent is azodicarbonamide and the wall material of the microcapsules is polyurea. The heat-expandable filler comprises hollow glass microspheres produced by 3M. The additives comprise 1.5% of a thixotropic agent, 0.5% of a defoaming agent and 0.3% of a leveling agent. The photoinitiator comprises 1-hydroxycyclohexyl phenyl ketone. The solvent comprises 10% of isopropanol.

[0072] Example 5

[0073] A photocurable composition comprises, by weight, 50% of a photocurable acrylic resin, 15% of a (meth)acrylic acid active diluent, 5% of a thermosensitive debonding agent, 5% of a heat-expanding filler, 3% of a photoinitiator and 10% of a solvent. The thermosensitive debonding agent is a heat-expanding microsphere. The heat-expanding filler is a hollow glass microsphere produced by 3M. The additives include 1.5% of a thixotropic agent, 0.5% of a defoaming agent and 0.3% of a leveling agent. The photoinitiator is 1-hydroxycyclohexyl phenyl ketone. The solvent is 10% of isopropyl alcohol.

[0074] The method for preparing the protective film layer is the same as that in Example 1.

[0075] Example 6

[0076] A photocurable composition comprises, by weight, 50% of a photocurable acrylic resin, 15% of a (meth)acrylic acid active diluent, 10% of a heat-expandable filler, 0.5% of an additive, 3% of a photoinitiator and 10% of a solvent. The heat-sensitive debonding agent comprises 5% of heat-expandable microspheres and 5% of microcapsules containing a thermal decomposition type foaming agent, wherein the foaming agent is azodicarbonamide and the wall material of the microcapsules is polyurea. The heat-expandable filler comprises hollow glass microspheres produced by 3M. The additive comprises 1.5% of a thixotropic agent, 0.5% of a defoaming agent and 0.3% of a leveling agent. The photoinitiator comprises 1-hydroxycyclohexyl phenyl ketone. The solvent comprises 10% of isopropanol.

[0077] The method for preparing the protective film layer is the same as that in Example 1.

[0078] The above Examples 1 to 6 are mixed and filtered according to the component ratio to form a uniform photosensitive liquid of the photocurable composition. And the protective film layer is formed according to the above-mentioned preparation method of the protective film layer. Its components and specific gravity refer to the following Table 1:

[0079] Table 1 Distribution ratio of each group of samples

[0080]

[0081] In order to verify the performance of the photocurable composition and the protective adhesive film layer of the present invention, the above six examples were subjected to physical and chemical property tests and stripping test.

[0082] Physical and chemical properties test

[0083] 1. Curing speed

[0084] Test method: Use UV-LED lamp with a wavelength of 365 nm or 395 nm as the light source, set different energy densities (800-1200 mJ / cm 2 ) and exposure time (5-15 seconds), and observe the curing effect.

[0085] Evaluation criteria: whether the cured layer is completely cured and whether there are softened or uncured areas.

[0086] 2. Hardness

[0087] Test method: Use a pencil hardness tester and test according to ASTM D3363 standard.

[0088] Evaluation criteria: Record the hardness level of the protective film layer.

[0089] 3.Solvent resistance

[0090] Test method: Soak the cured protective film layer in common organic solvents (such as ethanol, acetone, toluene, etc.) and observe its dissolution.

[0091] Evaluation criteria: Record the resistance time and appearance changes of the protective film layer in different solvents.

[0092] 4. Heat resistance

[0093] Test method: Place the cured protective film layer in a high temperature environment (150-250°C) and observe the changes in its physical and chemical properties.

[0094] Evaluation criteria: Record the color and shape changes of the protective film layer and whether there are cracks or peeling.

[0095] 5. Adhesion

[0096] Test method: Use the cross-cut method to test adhesion in accordance with ISO2409 standard.

[0097] Evaluation criteria: Record the adhesion level of the protective film layer.

[0098] Peelability test

[0099] 1. Peel force test

[0100] Test method: Bake the cured protective film at 200°C to reduce its adhesion, then use a blower or air gun to blow hot air and observe the peeling effect.

[0101] Hot air temperature: 200℃.

[0102] Wind strength: Use an industrial fan or air gun, set the wind speed to 10m / s (about 36km / h), and blow about 10cm away from the protective film layer.

[0103] Evaluation criteria: Record the peeling force, the difficulty of the peeling process, and the surface condition of the substrate after peeling.

[0104] 2. Surface condition of substrate after peeling

[0105] Test method: Inspect the substrate surface after peeling to see if there is any residue, scratches or other damage.

[0106] Evaluation criteria: Record the cleanliness and flatness of the substrate surface.

[0107] Test Results

[0108] Example 1

[0109] Cure Speed: Fully cured with no softened or uncured areas.

[0110] Hardness: HB grade.

[0111] Solvent resistance: No obvious dissolution after immersion in ethanol, acetone and toluene for 24 hours.

[0112] Heat resistance: No color change, cracks or peeling after being kept at 200℃ for 2 hours.

[0113] Adhesion: Grade 1.

[0114] Peeling force: relatively small. After blowing hot air with a fan (200℃, wind speed 10m / s) for 1 minute, the protective film layer can be easily peeled off and the surface of the substrate is clean.

[0115] Example 2

[0116] Cure Speed: Fully cured with no softened or uncured areas.

[0117] Hardness: HB grade.

[0118] Solvent resistance: No obvious dissolution after immersion in ethanol, acetone and toluene for 24 hours.

[0119] Heat resistance: No color change, cracks or peeling after being kept at 200℃ for 2 hours.

[0120] Adhesion: Grade 1.

[0121] Peeling force: relatively small. After blowing hot air with a fan (200℃, wind speed 10m / s) for 1 minute, the protective film layer can be easily peeled off and the surface of the substrate is clean.

[0122] Example 3

[0123] Cure Speed: Fully cured with no softened or uncured areas.

[0124] Hardness: HB grade.

[0125] Solvent resistance: No obvious dissolution after immersion in ethanol, acetone and toluene for 24 hours.

[0126] Heat resistance: No color change, cracks or peeling after being kept at 200℃ for 2 hours.

[0127] Adhesion: Grade 1.

[0128] Peeling force: relatively small. After blowing hot air with a fan (200℃, wind speed 10m / s) for 1 minute, the protective film layer can be easily peeled off and the surface of the substrate is clean.

[0129] Example 4

[0130] Cure Speed: Fully cured with no softened or uncured areas.

[0131] Hardness: HB grade.

[0132] Solvent resistance: No obvious dissolution after immersion in ethanol, acetone and toluene for 24 hours.

[0133] Heat resistance: No color change, cracks or peeling after being kept at 200℃ for 2 hours.

[0134] Adhesion: Grade 1.

[0135] Peeling force: relatively small. After blowing hot air with a fan (200℃, wind speed 10m / s) for 1 minute, the protective film layer can be easily peeled off and the surface of the substrate is clean.

[0136] Example 5

[0137] Cure Speed: Fully cured with no softened or uncured areas.

[0138] Hardness: HB grade.

[0139] Solvent resistance: No obvious dissolution after immersion in ethanol, acetone and toluene for 24 hours.

[0140] Heat resistance: No color change, cracks or peeling after being kept at 200℃ for 2 hours.

[0141] Adhesion: Grade 1.

[0142] Peeling force: relatively small. After blowing hot air with a fan (200℃, wind speed 10m / s) for 1 minute, the protective film layer can be easily peeled off and the surface of the substrate is clean.

[0143] Example 6

[0144] Cure Speed: Fully cured with no softened or uncured areas.

[0145] Hardness: HB grade.

[0146] Solvent resistance: No obvious dissolution after immersion in ethanol, acetone and toluene for 24 hours.

[0147] Heat resistance: No color change, cracks or peeling after being kept at 200℃ for 2 hours.

[0148] Adhesion: Grade 1.

[0149] Peeling force: relatively small. After blowing hot air with a fan (200℃, wind speed 10m / s) for 1 minute, the protective film layer can be easily peeled off and the surface of the substrate is clean.

[0150] Through the above tests, the photocurable composition and protective adhesive film layer of the present invention exhibit excellent physical and chemical properties and stripping properties. Fast curing speed, moderate hardness, good solvent resistance and heat resistance, strong adhesion and easy stripping. In particular, at 200°C, after blowing hot air with a fan or air gun (wind speed 10m / s) for 1 minute, the protective adhesive film layer can be easily peeled off, and the surface of the substrate after peeling is clean and intact. These properties make the photocurable composition and protective adhesive film layer of the present invention suitable for the protection needs of various circuit boards, especially for application scenarios where the protective adhesive needs to be easily removed at high temperatures.

[0151] The foregoing examples are merely illustrative and are used to explain some features of the method of the present invention. The appended claims are intended to claim the widest possible range that can be conceived, and the embodiments presented herein are only illustrations of selected implementations according to the combination of all possible embodiments. Therefore, it is the applicant's intention that the appended claims are not limited by the selection of examples that illustrate the features of the present invention. Some numerical ranges used in the claims also include sub-ranges within them, and changes in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A photocurable composition, characterized in that: In terms of weight percentage, it includes the following components: 50% to 70% of light-curing acrylate resin, 15% to 25% of (meth) acrylic acid active diluent, 5% to 15% of heat-sensitive debonding agent, 0.5% to 5% of additives, 3% to 7% of photoinitiator and 10% to 50% of solvent.

2. The photocurable composition according to claim 1, characterized in that The photocurable acrylate resin includes at least one of epoxy acrylate, polyurethane acrylate, polyester acrylate, polyether acrylate, and bis(4-acryloxyphenyl) carbonate.

3. The photocurable composition according to claim 1, characterized in that The (meth)acrylic acid reactive diluent includes at least one of isobornyl acrylate, 2-hydroxyethyl acrylate, phenoxyethyl acrylate, and propoxy tripropylene glycol acrylate.

4. The photocurable composition according to claim 1, wherein The heat-sensitive debonding agent is a heat-expandable microsphere or a microcapsule containing a thermally decomposable foaming agent.

5. The photocurable composition according to claim 4, characterized in that The foaming agent in the microcapsule containing the thermal decomposition type foaming agent is selected from at least one of azodicarbonamide, p-toluenesulfonyl hydrazide or ammonium bicarbonate.

6. The photocurable composition according to claim 4, characterized in that The wall material of the microcapsule containing the thermal decomposition type foaming agent is polyurea, phenolic resin or melamine formaldehyde resin.

7. The photocurable composition according to claim 1, wherein It also includes 0.5%-15% of thermal expansion filler, wherein the thermal expansion filler is hollow glass microspheres or polymer microspheres with a particle size of 10-100 microns; and / or The additive includes at least one of a thixotropic agent, a defoaming agent and a leveling agent.

8. The photocurable composition according to claim 1, wherein The photoinitiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-phenyl-1-[4-(2H-benzotriazol-2-yl)-3-tert-butylphenyl]-2-(O-methylmorpholino)propane.

9. A protective adhesive, characterized in that: The adhesive is prepared using the photocurable composition according to any one of claims 1 to 7.

10. A circuit board protection method, characterized in that: The following steps are involved: S1: applying the protective glue as claimed in claim 9 on the components to be shielded on the circuit board; S2: irradiating the circuit board with ultraviolet light or visible light at room temperature to solidify the protective glue to form a protective layer; S3: Apply conformal coating on the circuit board; S4: Bake the plate at 150-250°C to reduce the adhesion of the protective glue; S5: Peel off the protective glue and conformal coating on the components to be masked.

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