UV adhesive as well as preparation method and application thereof

Abstract

The invention provides a UV (ultraviolet) adhesive which is prepared from the following raw materials in percentage by mass: not less than 50wt% of isocyanate-terminated prepolymer A, not less than 5wt% of acrylate B, a photoinitiator with the absorption spectrum wavelength of lambda1-lambda2 and a photobase generator with the absorption spectrum wavelength of lambda3-lambda4, the photoinitiator and the photobase generator meet the following condition: lambda3 is greater than lambda2; the chemical structure of the photobase generator meets the general formula I, the general formula I is # imgabs0 #, at least one of X and Y is a substituent group of polycyclic aromatic hydrocarbon, and at least one of X and Y is a substituent group containing secondary nitrogen atoms and / or tertiary nitrogen atoms. The UV adhesive can be cured under illumination of at least one part of the wavelength range of lambda3-lambda4 to form an adhesive layer with good adhesive property, and after the adhesive layer is illuminated by at least one part of the wavelength range of lambda1-lambda2, the adhesive property of the adhesive layer is reduced, so that the adhesive layer is stripped without residual adhesive.

Description

Technical Field

[0001] The present invention relates to the field of adhesives, and in particular to a UV adhesive and a preparation method and application thereof. Background Art

[0002] Wafer cutting process is an indispensable part of the semiconductor chip manufacturing process. During the wafer processing, due to the thinness of the wafer, it is difficult to directly cut and transfer a single-layer wafer. Therefore, it is necessary to use tape to stick to the surface of the wafer to facilitate wafer transfer, cutting and other operations. After completing the wafer cutting and other processing operations, the tape on the wafer needs to be peeled off. If the adhesion of the tape to the wafer is low, it cannot provide good protection during the wafer preparation process. If the adhesion of the tape to the wafer is too strong, it is easy to leave residual adhesive on the surface of the wafer or even damage the wafer when peeling off the tape.

[0003] The base material layer used in the existing wafer cutting protection tape is mostly polyvinyl chloride (PVC) or polyolefin (PO), but the temperature resistance of PVC and PO is poor. During the tape preparation process, the adhesive layer can only be attached by transfer coating. The tape preparation efficiency is not high and the process is relatively complicated.

[0004] Although the above problems can be avoided by using UV curing method to prepare adhesive tape, there are still some disadvantages of UV curing adhesive tape, such as limited curing depth, poor applicability of colored system and opaque substrate. There are few UV curing adhesive tapes that can match the conditions of UV equipment with commonly used light intensity on the market, which greatly limits the development and application of UV curing adhesive tape.

[0005] Therefore, a UV curing tape is developed which has good initial adhesion after UV curing and is not easy to leave residual adhesive after the adhesive layer is peeled off. Summary of the invention

[0006] The object of the present invention is to provide a UV adhesive and a preparation method and application thereof. The UV adhesive can be cured under light in a wavelength range including at least a part of λ3 to λ4 to form an adhesive layer with good bonding performance. After the adhesive layer is exposed to light in a wavelength range including at least a part of λ1 to λ2, the bonding performance of the adhesive layer decreases, so that the adhesive layer can be peeled off without residual adhesive.

[0007] According to one aspect of the present invention, a UV adhesive is provided. The raw materials for preparing the UV adhesive include an isocyanate-terminated prepolymer A with a mass proportion of not less than 50wt%, an acrylate B with a mass proportion of not less than 5wt%, a photoinitiator with an absorption spectrum wavelength of λ1 to λ2, and a photobase generator with an absorption spectrum wavelength of λ3 to λ4, wherein the photoinitiator and the photobase generator satisfy: λ3>λ2;

[0008] The chemical structure of the photobase generator satisfies the general formula I: At least one of X and Y is a substituent of polycyclic aromatic hydrocarbon, and at least one of X and Y is a substituent containing a secondary nitrogen atom and / or a tertiary nitrogen atom.

[0009] By introducing photobase generators and photoinitiators with different absorption spectrum wavelengths into UV adhesives, the bonding properties of the adhesive layer formed by the UV adhesive can be flexibly adjusted according to actual needs, so that the adhesive layer has good initial adhesion. When the adhesive layer needs to be peeled off, the adhesive layer can also be easily peeled off from the surface of the bonded object without residual adhesive. First, based on the selection of the absorption spectrum wavelengths of the photoinitiator and the photobase generator, the absorption spectrum wavelengths of the photobase generator and the photoinitiator do not overlap, and the absorption spectrum wavelength range of the photobase generator is greater than the absorption spectrum wavelength range of the photoinitiator, and the chemical structure of the photobase generator is further optimized. On the one hand, it provides a basis for adjusting the absorption spectrum wavelength of the photobase generator. On the other hand, a non-phosphate system polysubstituted amine (i.e., containing secondary nitrogen atoms and / or tertiary nitrogen atoms) whose chemical structure satisfies the general formula I is selected as the photobase generator. The photobase generator has at least one polycyclic aromatic hydrocarbon structure and a polysubstituted amine group, which is conducive to improving the initiation activity of the photobase generator and improving the solubility of the photobase generator in the UV adhesive, thereby improving the light source adaptability of the UV adhesive.

[0010] When the UV adhesive needs to form an adhesive layer, the UV adhesive is first irradiated with a light source having a wavelength range including at least a part of λ3 to λ4, so that the photobase generator takes effect and produces alkaline substances, which catalyze the cross-linking reaction of the isocyanate-terminated prepolymer A and the acrylate B, thereby improving the bonding performance of the adhesive layer formed by the UV adhesive and the interfacial peeling force between the adhesive layer and the bonded object. On the one hand, the UV adhesive requires low UV initiation energy, low curing temperature, and strong light source adaptability, which can match most light source equipment on the market, and the curing condition is ≥200mJ / cm 2That is, there is no need to purchase additional lighting equipment with a specific wavelength, which reduces the application cost of the UV adhesive. On the other hand, the UV adhesive does not immediately and quickly undergo a curing reaction after being exposed to ultraviolet light, but has a certain induction period to delay the curing reaction. During this delay time, the production personnel can complete the assembly of the substrate and the adhesive layer. Therefore, even if the substrate has poor light transmittance or is an opaque material, it can effectively excite the photobase generator in the UV adhesive, so that the adhesive layer formed by the UV adhesive has high bonding performance. Then, after the adhesive layer formed by the UV adhesive has been firmly bonded to the object to be bonded and the protection of the object to be bonded is completed, when the adhesive layer on the surface of the bonded object needs to be peeled off, a light source with a wavelength range including at least a part of λ1 to λ2 is used to irradiate the adhesive layer, so that the photoinitiator takes effect, promotes further polymerization of the compounds in the adhesive layer, causes the adhesive layer to shrink in a certain range of volume, and produces wrinkles on the bonding surface of the adhesive layer and the object, thereby reducing the bonding points between the adhesive layer and the bonded object, greatly reducing the peeling strength of the adhesive layer, and reducing residual glue.

[0011] In particular, the UV adhesive provided by the present invention can be applied to wafer cutting or wafer protection. Since the thickness of the wafer is relatively small, the wafer is brittle and fragile during the wafer cutting and wafer expansion operations. By using the tape of the above-mentioned UV adhesive to encapsulate and protect the wafer surface, the high bonding performance achieved by the photobase generator in the UV adhesive can effectively avoid damage to the wafer during processing. After completing processing operations such as wafer cutting, the tape on the wafer needs to be peeled off. The UV viscosity-reducing effect achieved by the photoinitiator in the UV adhesive can reduce residual adhesive and damage to the wafer during the peeling stage, thereby improving the wafer preparation yield.

[0012] Preferably, the absorption wavelength of the photoinitiator is 200 to 300 nm. By making the absorption wavelength of the photobase generator much greater than that of the photoinitiator, the energy difference of the light required between the two is obvious. In the process of preparing the adhesive tape, the light of the wavelength suitable for the photobase generator is used, which can effectively induce the reaction of the photobase generator and avoid the initiation of photolysis of the photoinitiator, and has a good effect.

[0013] Preferably, calculated by mass ratio, the isocyanate-terminated prepolymer A: acrylate B = 75-95: 5-25.

[0014] Preferably, in the raw materials for preparing the UV adhesive, the mass proportion of the photobase generator is 3 to 6 wt %.

[0015] Preferably, in the raw materials used to prepare the UV adhesive, the mass proportion of the photoinitiator is 1 to 5 wt %.

[0016] Preferably, at least one of X and Y is a cyclic amine group. Based on the selection of the chemical structure of the photobase generator, the structure of the substituent containing secondary nitrogen atoms and / or tertiary nitrogen atoms is further optimized, thereby simultaneously improving the reactivity and stability of the photobase generator. On the one hand, the photobase generator can be quickly effective under the light of its corresponding wavelength range, effectively improving the initial adhesion of the adhesive layer formed by the UV adhesive; on the other hand, the stability of the photobase generator in the process of preparing the UV adhesive or under light of other wavelength ranges can be improved, and it is not easily affected by light of other wavelengths and decomposed.

[0017] Preferably, the cyclic amine group comprises At least one of the following, wherein n=1 to 4. In the above structural formula, the dotted line represents the site where the cyclic amine group is connected to the ester group.

[0018] Preferably, among the substituents of the polycyclic aromatic hydrocarbons, the polycyclic aromatic hydrocarbons include benzophenone, anthraquinone, thioxanthene, and thioxanthone.

[0019] Alternatively, in the chemical structure of the photobase generator, the polycyclic aromatic hydrocarbon is directly linked to the ester group.

[0020] Optionally, in the chemical structure of the photobase generator, the substituent of the polycyclic aromatic hydrocarbon further includes an alkyl group or a hydroxyalkyl group having no more than 3 carbon atoms.

[0021] Preferably, the alkyl group in the substituent of the polycyclic aromatic hydrocarbon includes at least one of methylene, ethylene and propylene. Propylene In the above structural formula, the dotted lines represent the sites where the alkyl group is connected to the polycyclic aromatic hydrocarbon and the alkyl group is connected to the ester group.

[0022] Preferably, the hydroxyalkyl group in the substituent of the polycyclic aromatic hydrocarbon includes at least one of hydroxymethylene, hydroxyethylene and hydroxypropylene, i.e., hydroxymethylene (-CH(OH)-), hydroxyethylene Hydroxypropylene In the aforementioned structural formula, the dotted lines represent the sites where the hydroxyalkyl group is connected to the polycyclic aromatic hydrocarbon and the hydroxyalkyl group is connected to the ester group.

[0023] For example, the photobase generator can be selected from 1-(anthraquinone-2-yl)ethylimidazole-1-carboxylic acid 9-Anthracenemethylpiperidine-1-carboxylic acid tert-butyl ester 1-(Anthraquinone-2-yl)ethyl N-cyclohexylcarbamic acid 2-(9-Oxoxanthene-2-yl)-3-hydroxypropionic acid 1,8-diazabicyclo[5.4.0]undec-7-ene salt wait.

[0024] Preferably, the photoinitiator includes at least one of benzoin bisether, methyl o-benzoylbenzoate, benzophenone, 4-chlorobenzophenone, 2-hydroxy-1-(4-(2-hydroxy-2-methylpropionylphenyl)benzyl)-2-methyl-1-propanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxy-cyclohexyl-phenyl ketone. Among them, the effective absorption peak of benzoin bisether (BDK) is 205-253nm, the effective absorption main peak of methyl o-benzoylbenzoate (OMBB) is 204nm and 253nm, the effective absorption main peak of benzophenone (BP) is 250nm, the effective absorption main peak of 4-chlorobenzophenone (CBP) is 254nm, the effective absorption main peak of 2-hydroxy-1-(4-(2-hydroxy-2-methylpropionylphenyl)benzyl)-2-methyl-1-propanone is 259nm, the effective absorption main peak of 2-hydroxy-2-methyl-1-phenyl-1-propanone is 244nm, and the effective absorption main peak of 1-hydroxy-cyclohexyl-phenyl ketone is 246nm and 278nm.

[0025] Preferably, the weight average molecular weight of the isocyanate-terminated prepolymer A is 1000-3000, and the isocyanate grafting rate is 0.5-2%. By selecting the isocyanate-terminated prepolymer A that meets the above molecular weight requirements and grafting rate requirements to prepare the UV adhesive, the reaction degree between the isocyanate-terminated prepolymer A and the acrylate B can be improved, and the structural strength and bonding performance of the adhesive layer formed by the UV adhesive can be improved, and it is not easy to leave residual adhesive after the adhesive layer is peeled off. It should be noted that the molecular weight of the isocyanate-terminated polyurethane prepolymer used in commercially available UV glue is usually 600-1500.

[0026] Preferably, the raw materials used to prepare the isocyanate-terminated prepolymer A include acrylate monomers and isocyanate monomers, the acrylate monomers include a first component and a second component, the first component includes at least one of isooctyl acrylate, butyl acrylate, and methyl methacrylate, and the second component includes acrylic acid, hydroxyethyl methacrylate, and glycidyl methacrylate. By selecting the first component and the second component as acrylate monomers, the adhesive layer formed by the UV adhesive can maintain good flexibility while increasing the hardness and adhesion of the adhesive layer.

[0027] Preferably, the isocyanate monomer includes at least one of toluene diisocyanate and diphenylmethane diisocyanate.

[0028] Preferably, in the raw materials for preparing the isocyanate-terminated prepolymer A, the mass ratio of the acrylate monomer to the isocyanate monomer is 85-95:1-15.

[0029] Preferably, the acrylate functionality of acrylate B is not less than 3. Further, the acrylate B with an acrylate functionality of not less than 3 is selected to prepare the UV adhesive, which effectively regulates the reactive bonding groups and reactivity of the raw materials, improves the crosslinking degree inside the adhesive layer, and enhances the structural strength and bonding performance of the adhesive layer. The acrylate functionality refers to the number of the acrylate functional group in the chemical structure of acrylate B.

[0030] Preferably, the acrylate B includes at least one of dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, and ethoxylated trimethylolpropane triacrylate.

[0031] Preferably, the raw materials for preparing the glue layer also include polyols.

[0032] Optionally, the polyol includes at least one of polyester polyol and polyether polyol.

[0033] Preferably, the molecular weight of the polyol is no greater than 1,000.

[0034] Preferably, the raw materials for preparing the adhesive layer further include a thermal initiator, and the thermal initiator includes at least one of lauroyl peroxide, azobisisobutyronitrile, azobisisoheptylnitrile, and tert-butyl peroxy-2-ethylhexanoate.

[0035] Preferably, the raw materials used to prepare the adhesive layer also include a curing agent, an anti-aging agent, and a leveling agent.

[0036] According to another aspect of the present invention, a method for preparing the above-mentioned UV adhesive is provided, comprising the following operations: mixing the photobase generator, acrylate monomer and isocyanate monomer, using the resulting mixed solution as a reaction base solution, allowing the materials in the reaction base solution to undergo prepolymerization at 50 to 70° C. to form the isocyanate-terminated prepolymer A; then, mixing the isocyanate-terminated prepolymer A, the acrylate B and the remaining auxiliary agent, and maintaining the reaction temperature of the reaction system at 50 to 60° C. during the mixing process.

[0037] Preferably, in the process of preparing the isocyanate-terminated prepolymer A, the acrylate monomer is first mixed with the thermal initiator, and the resulting reaction system is reacted at a temperature of 50 to 70° C. for 2 to 4 hours; then, a polyol is added to the reaction system, and the reaction system is reacted at a temperature of 50 to 70° C. for 2 to 4 hours; then, an isocyanate monomer, a catalyst and a photobase generator are added to the reaction system, and the reaction system is reacted at a temperature of 50 to 70° C. for 2 to 4 hours to obtain the isocyanate-terminated prepolymer A.

[0038] Preferably, the acrylate monomer is treated to remove water so that the water content of the acrylate monomer is not higher than 5000 ppm.

[0039] Preferably, the polyol is treated to remove water so that the water content of the polyol is not higher than 5000 ppm.

[0040] Preferably, when the auxiliary agent includes a catalyst, the catalyst is added during the step of adding the photobase generator.

[0041] According to another aspect of the present invention, there is provided an adhesive tape comprising a substrate and an adhesive layer, wherein the adhesive layer is made of the above-mentioned UV adhesive.

[0042] Preferably, the substrate includes at least one of polyvinyl chloride (PVC), polyolefin (PO), polyethylene terephthalate (PET), and thermoplastic polyurethane (TPU).

[0043] According to another aspect of the present invention, there is provided application of the above-mentioned UV adhesive or the above-mentioned tape in the field of wafer processing or chip manufacturing. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0045] Experiment 1

[0046] Experimental Group 1

[0047] This implementation group provides a UV adhesive.

[0048] (1) The components of UV adhesive are shown in Table 1.

[0049] Table 1. Components of UV adhesives

[0050]

[0051] Among them, the absorption spectrum wavelength of benzoin bisether (BDK) is 205-253 nm, and the absorption wavelength is less than 300 nm.

[0052] Table 2. Components of isocyanate-terminated prepolymer A

[0053]

[0054]

[0055] Among them, the CAS number of 1-(anthraquinone-2-yl)ethylimidazole-1-carboxylic acid is 1418139-51-1, and the chemical structure is The absorption spectrum wavelength of 1-(anthraquinone-2-yl)ethylimidazole-1-carboxylic acid is 345-385 nm, and the absorption wavelength is ≥300 nm.

[0056] The preparation method of isocyanate-terminated prepolymer A comprises the following operations:

[0057] S1. The acrylate monomer is heated to remove water to a water content of not more than 500 ppm, and the acrylate monomer and the thermal initiator are mixed at a reaction temperature of 60±10°C, and the reaction system thus obtained is kept at a temperature of 60±10°C for 2 hours;

[0058] S2. The polyol is heated to remove water until the water content is not higher than 500 ppm, and then the polyol is added to the reaction system, and the reaction system is kept stirred at 60 ± 10 ℃ for 3 hours;

[0059] S3. Add isocyanate monomer, catalyst and photobase generator to the reaction system, keep the reaction system at 60±10°C for 2 hours to obtain isocyanate-terminated prepolymer A. The weight average molecular weight Mw of the isocyanate-terminated prepolymer A is measured to be 2640, and the grafting rate of isocyanate is 1%.

[0060] The preparation method of UV adhesive includes the following operations:

[0061] Mix acrylate B and isocyanate-terminated prepolymer A according to the above ratio, add photoinitiator and curing agent, anti-aging agent, leveling agent and other processing aids and stir evenly, and maintain the reaction temperature of the reaction system at 50-60°C during the mixing process.

[0062] In other embodiments, the types and amounts of isocyanate-terminated prepolymer A, acrylate B, photoinitiator, curing agent, anti-aging agent and leveling agent can be adjusted according to actual application requirements, or the molecular weight and isocyanate grafting rate of isocyanate-terminated prepolymer A can be adjusted, or the types and amounts of acrylate monomer, isocyanate monomer, polyol, photobase generator, thermal initiator and catalyst can be adjusted. For example, acrylate B can be selected from at least one of dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate and ethoxylated trimethylolpropane triacrylate; for example, the photoinitiator can be selected from at least one of benzoin diether, methyl o-benzoylbenzoate, benzophenone, 4-chlorobenzophenone, 2-hydroxy-1-(4-(2-hydroxy-2-methylpropionylphenyl)benzyl)-2-methyl-1-propanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxy-cyclohexyl-phenyl ketone.

[0063] (2) Tape

[0064] The adhesive tape comprises an adhesive layer and a substrate. The adhesive layer is made of the UV adhesive, and the substrate is made of a polyvinyl chloride (PVC) film.

[0065] The method for preparing the tape includes the following operations:

[0066] The above-mentioned UV adhesive is coated on the substrate, and UV light is irradiated using a light source device with an emission wavelength of 365nm, the irradiation height is 15-30cm, and the curing condition is ≥200mJ / cm 2 , reel it up and get the tape.

[0067] In this experiment, different UV adhesives and tapes were prepared with the type of photobase generator as a variable, and the product numbers and the specific conditions of the corresponding photobase generators are shown in Table 3. Among the UV adhesives and tapes prepared in this experimental group, except for the variables shown in Table 3, the other raw material ratios, structures, and preparation methods were strictly consistent.

[0068] Table 3. Details of product numbers and corresponding variables in Experiment 1

[0069]

[0070]

[0071] Note: The absorption spectrum wavelengths of the photobase generators used in experimental groups 1 to 4 and comparative group 1 are all ≥ 300 nm. The absorption spectrum wavelengths of the photobase generators provided by comparative group 2 are mainly between 197 and 254 nm.

[0072] Among them, the photobase generator used in Experimental Group 4 was prepared by the following reaction route:

[0073]

[0074] The specific reaction steps include:

[0075] (1) According to the amount of the substance, 58.5 parts of raw material B were added in batches to a mixture of 19.5 parts of raw material A and 900 parts of concentrated sulfuric acid, and stirred at room temperature for 1 hour, then stirred at 80° C. for 8 hours, filtered, and dried to obtain an intermediate product C.

[0076] (2) Take 10 parts of the intermediate product C and dissolve them in tetrahydrofuran. After the solution is clarified, add 10 parts of 1,8-diazabicycloundec-7-ene (DBU) dropwise. When a brown viscous liquid appears at the bottom of the flask, pour off the supernatant, add a certain volume of tetrahydrofuran for washing, and repeat three times to obtain 2-(9-oxoxanthen-2-yl)-3-hydroxypropionic acid 1,8-diazabicyclo[5.4.0]undec-7-ene salt.

[0077] Test Example 1

[0078] Test subjects: The tapes prepared from experimental groups 1 to 4 and control groups 1 to 2 in Experiment 1 were used as test subjects.

[0079] Test items and test methods:

[0080] (1) Peeling force before UV irradiation: Referring to the test method in GB / T 2792-2014 Test method for peeling strength of adhesive tape, the test object was cut into a size of 24mm*150mm, and the release layer of the test object was peeled off, and the adhesive layer was attached to the steel plate, and rolled back and forth with a 1kg rubber roller three times, and placed in an environment of 23±1℃ and 50±5%RH for 20min. Then, the test object was peeled off from the steel plate at a peeling speed of 300mm / min and a peeling angle of 180°, and the peeling force of the test object before UV irradiation was recorded.

[0081] (2) Peel strength after UV irradiation: Referring to the test method in GB / T 2792-2014 Test method for peel strength of adhesive tape, the test object was cut into a size of 24 mm*150 mm, and the release layer of the test object was peeled off, and the adhesive layer was attached to the steel plate. A 1 kg rubber roller was used to roll back and forth three times. After being placed in an environment of 23±1°C and 50±5% RH for 20 min, the test object was cured under the condition of 250 mJ / cm 2 The test object was irradiated with UV light to excite the photoinitiator and left for 30 minutes. Then, the test object was peeled off from the steel plate at a peeling speed of 300 mm / min and a peeling angle of 180°, and the peeling force of the test object after UV irradiation was recorded.

[0082] (3) Wafer defect rate: The test object was attached to the wafer surface, cut and expanded, and then irradiated with 250 mJ / cm 2 UV light irradiation, placed for 30 minutes, to obtain wafer samples. Repeat the preparation of 10,000 wafer samples. When the wafer samples have cracks, scratches, breakage or residual glue on the surface, they are considered defective. Wafer defect rate = (number of defective wafers / number of wafer samples) × 100%.

[0083] Test results: The test results are shown in Table 4.

[0084] Table 4. Test results of the subjects

[0085]

[0086]

[0087] Note: The “-” in the wafer defect rate in Table 4 means “the tape and wafer cannot be peeled off or there is a large amount of residual adhesive on the wafer surface”.

[0088] Result analysis:

[0089] By comparing the test performance of the tapes provided by experimental groups 1 to 4 and comparative groups 1 to 2 in Table 4, it can be found that, compared with the tapes of comparative groups 1 to 2, the tapes provided by experimental groups 1 to 4 have a peeling force of ≥8.9N / 25mm before UV irradiation, a peeling force of ≤0.8N / 25mm after UV irradiation, and a wafer defect rate of ≤1.10%. This shows that when the UV adhesive forming the tape uses a photobase generator that satisfies the general formula I, the tape has excellent adhesive properties before UV irradiation, a small peeling force after UV irradiation, and it is not easy to leave residual adhesive on the wafer surface after peeling the tape. Among them, by comparing the tapes provided by experimental group 2 and comparative group 1, it can be found that although the chemical structures of the photobase generators used in experimental group 2 and comparative group 1 both include tertiary amine, the photobase generator of experimental group 2 satisfies the general formula I, and the photobase generator of comparative group 1 has no ester group and no polycyclic aromatic hydrocarbons, so the photobase generator used in comparative group 1 does not satisfy the general formula I. The photobase generator used in comparison group 2 does not satisfy general formula I and the absorption spectrum wavelength of the photobase generator used in comparison group 2 overlaps with the absorption spectrum wavelength of the photoinitiator, which is reflected in the low peeling force of the tape before UV irradiation and the high peeling force after UV irradiation. Combining the wafer defect rates measured in comparison groups 1-2 and experimental groups 1-4, it is further explained that when faced with the application requirements of good bonding performance and no residual adhesive left after peeling, the tape formed by the UV adhesive using the photobase generator whose chemical structure satisfies general formula I has better comprehensive performance.

[0090] By comparing the tapes provided by experimental groups 1 to 4, it can be found that compared with the tape provided by experimental group 3, the tapes provided by experimental groups 1 to 2 and experimental group 4 have higher peeling force before UV irradiation and smaller peeling force after UV irradiation, which indicates that on the basis that the photobase generator satisfies the general formula I, when the substituent (X group) containing secondary amine and / or tertiary amine in the structure of the photobase generator includes a cyclic amine group, the adhesive layer formed by the UV adhesive can have excellent adhesive properties before UV irradiation and small peeling force after UV irradiation. At the same time, among the tapes provided by experimental groups 1 to 4, the tape of experimental group 1 has the best comprehensive performance, which indicates that when the polycyclic aromatic hydrocarbons of the photobase generator include anthraquinone and the cyclic amine structure of the photobase generator includes imidazole, the adhesive tape obtained has better adhesive properties before UV irradiation and smaller peeling force after UV irradiation, and the corresponding tape can reduce the wafer defect rate when used in the field of wafer intelligence manufacturing.

[0091] Experiment 2

[0092] In this experiment, tapes were prepared by referring to the UV adhesive prepared in experimental group 1, and experimental groups 5, 6, 7, 8, 9 and 10 were set up.

[0093] Experimental Group 5:

[0094] This experimental group prepared a UV adhesive and tape with reference to the preparation method provided by experimental group 1. The difference between this experimental group and experimental group 1 is that the weight average molecular weight of the isocyanate-terminated prepolymer A is adjusted to 800±50. Specifically, during the preparation of the isocyanate-terminated prepolymer A, when it is detected that the weight average molecular weight of the isocyanate-terminated prepolymer A falls within the above range, the temperature is lowered and further reaction is stopped. In addition, the other materials in the UV adhesive formula used in this experimental group are consistent with the materials and proportions used in the UV adhesive formula of experimental group 1.

[0095] Experimental Group 6:

[0096] This experimental group prepared a UV adhesive and tape by referring to the preparation method provided by experimental group 1. The difference between this experimental group and experimental group 1 is that the weight average molecular weight of the isocyanate-terminated prepolymer A is adjusted to 1000±50. Specifically, in the process of preparing the isocyanate-terminated prepolymer A, when it is detected that the weight average molecular weight of the isocyanate-terminated prepolymer A falls within the above range, the temperature is lowered and further reaction is stopped. In addition, the other materials in the UV adhesive formula used in this experimental group are consistent with the materials and proportions used in the UV adhesive formula of experimental group 1.

[0097] Experimental Group 7:

[0098] This experimental group prepared a UV adhesive and tape by referring to the preparation method provided by experimental group 1. The difference between this experimental group and experimental group 1 is that the weight average molecular weight of the isocyanate-terminated prepolymer A is adjusted to 2000±50. Specifically, in the process of preparing the isocyanate-terminated prepolymer A, when it is detected that the weight average molecular weight of the isocyanate-terminated prepolymer A falls within the above range, the temperature is lowered and further reaction is stopped. In addition, the other materials in the UV adhesive formula used in this experimental group are consistent with the materials and proportions used in the UV adhesive formula of experimental group 1.

[0099] Experimental Group 8:

[0100] This experimental group prepared a UV adhesive and tape by referring to the preparation method provided by experimental group 1. The difference between this experimental group and experimental group 1 is that the weight average molecular weight of the isocyanate-terminated prepolymer A is adjusted to 3500±50. Specifically, in the process of preparing the isocyanate-terminated prepolymer A, when it is detected that the weight average molecular weight of the isocyanate-terminated prepolymer A falls within the above range, the temperature is lowered and further reaction is stopped. In addition, the other materials in the UV adhesive formula used in this experimental group are consistent with the materials and proportions used in the UV adhesive formula of experimental group 1.

[0101] Experimental Group 9:

[0102] This experimental group prepared a UV adhesive and tape by referring to the preparation method provided by experimental group 1. The difference between this experimental group and experimental group 1 is that the grafting rate of isocyanate-terminated prepolymer A was adjusted to 0.5%. Specifically, in the process of preparing isocyanate-terminated prepolymer A, the amount of isocyanate monomer was adjusted to 4 parts. In addition, the other materials in the UV adhesive formula used in this experimental group were consistent with the materials and proportions used in the UV adhesive formula of experimental group 1.

[0103] Experimental Group 10:

[0104] This experimental group prepared a UV adhesive and tape by referring to the preparation method provided by experimental group 1. The difference between this experimental group and experimental group 1 is that the grafting rate of isocyanate-terminated prepolymer A was adjusted to 2.0%. Specifically, in the process of preparing isocyanate-terminated prepolymer A, the amount of isocyanate monomer was adjusted to 17 parts. In addition, the other materials in the UV adhesive formula used in this experimental group were consistent with the materials and proportions used in the UV adhesive formula of experimental group 1.

[0105] Test Example 2

[0106] Test subjects: The tapes prepared from Experimental Groups 5 to 10 in Experiment 2 were used as test subjects.

[0107] Test items and test methods:

[0108] (1) Peel force before UV irradiation: The peel force test before UV irradiation in this test example and the peel force test before UV irradiation in Test Example 1 use the same test equipment, test conditions, and test operations.

[0109] (2) Peel force after UV irradiation: The peel force test after UV irradiation in this test example uses the same test equipment, test conditions, and test operations as those used in the peel force test after UV irradiation in Test Example 1.

[0110] (3) Wafer defect rate: The wafer defect rate test in this test example uses the same test equipment, test conditions, and test operations as the wafer defect rate test in Test Example 1. 10,000 wafer samples are prepared repeatedly. When a wafer sample has cracks, scratches, or is broken, or has residual adhesive on the surface, it is considered a defective product. Wafer defect rate = (number of defective wafers / number of wafer samples) × 100%.

[0111] Test results: The variables between the test objects and the test results of the test cases are shown in Table 5. For the convenience of comparison, Table 5 also includes the relevant information and performance indicators of the UV adhesive of Experimental Group 1.

[0112] Table 5. Variables and test results among participants

[0113]

[0114] Result analysis:

[0115] Comparing the test performance of the tapes provided by experimental group 1 and experimental groups 5 to 8 in Table 5, it can be found that the peeling force of the tapes provided by experimental groups 1 and experimental groups 6 to 7 before UV irradiation is greater than 10.2N / 25mm, the peeling force is ≤0.5N / 25mm after UV irradiation, and the wafer defect rate is ≤0.21%. This shows that when the weight average molecular weight of the isocyanate-terminated prepolymer A is 1000 to 3000, the structural strength and bonding performance of the adhesive layer formed by the UV adhesive are good, and it is not easy to leave residual adhesive after UV irradiation.

[0116] By comparing the tapes provided by experimental group 1 with those provided by experimental groups 9 to 10, it can be found that when the isocyanate grafting rate of isocyanate-terminated prepolymer A is in the range of 0.5 to 2%, the tape formed by the UV adhesive including the raw materials of isocyanate-terminated prepolymer A has excellent bonding properties before UV irradiation, is easy to peel off from the wafer surface after UV irradiation, and is not prone to residual adhesive on the wafer surface, thereby reducing the wafer defect rate.

[0117] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A UV adhesive, characterized in that: The raw materials used to prepare the UV adhesive include an isocyanate-terminated prepolymer A with a mass proportion of not less than 50wt%, an acrylate B with a mass proportion of not less than 5wt%, a photoinitiator with an absorption spectrum wavelength of λ1 to λ2, and a photobase generator with an absorption spectrum wavelength of λ3 to λ4, wherein the photoinitiator and the photobase generator satisfy: λ3>λ2; The chemical structure of the photobase generator satisfies the general formula I: At least one of X and Y is a substituent of polycyclic aromatic hydrocarbons, and at least one of X and Y is a substituent containing a secondary nitrogen atom and / or a tertiary nitrogen atom.

2. The UV adhesive according to claim 1, characterized in that: At least one of the X and the Y is a cyclic amine group.

3. The UV adhesive according to claim 1, characterized in that: The photoinitiator includes at least one of benzoin diether, methyl o-benzoylbenzoate, benzophenone, 4-chlorobenzophenone, 2-hydroxy-1-(4-(2-hydroxy-2-methylpropionylphenyl)benzyl)-2-methyl-1-propanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxy-cyclohexyl-phenyl ketone.

4. The UV adhesive according to claim 1, characterized in that: The weight average molecular weight of the isocyanate-terminated prepolymer A is 1000-3000, and the isocyanate grafting rate is 0.5-2%.

5. The UV adhesive according to claim 1, characterized in that: The raw materials used to prepare the isocyanate-terminated prepolymer A include acrylate monomers and isocyanate monomers. The acrylic acid ester monomer comprises a first component and a second component, wherein the first component comprises at least one of isooctyl acrylate, butyl acrylate and methyl methacrylate, and the second component comprises acrylic acid, hydroxyethyl methacrylate and glycidyl methacrylate.

6. The UV adhesive according to claim 1, characterized in that: The isocyanate monomer includes at least one of toluene diisocyanate and diphenylmethane diisocyanate.

7. The UV adhesive according to claim 1, characterized in that: The acrylate functionality of the acrylate B is not less than 3.

8. A method for preparing the UV adhesive according to any one of claims 1 to 7, characterized in that: The following operations are included: The photobase generator, acrylate monomer and isocyanate monomer are mixed to obtain a mixed solution as a reaction base solution, and the materials in the reaction base solution are prepolymerized at 50-70° C. to form the isocyanate-terminated prepolymer A; Next, the isocyanate-terminated prepolymer A, the acrylate B and the remaining auxiliary agent are mixed, and the temperature of the reaction system is maintained at 50-60° C. during the mixing process.

9. An adhesive tape, characterized in that: The invention comprises a substrate and an adhesive layer, wherein the adhesive layer is made of the UV adhesive as claimed in any one of claims 1 to 7.

10. Use of the UV adhesive according to any one of claims 1 to 7 or the tape according to claim 9 in the field of wafer processing or chip manufacturing.

Images