Low shrinkage stress uv adhesive, uv debonding film and preparation method and application thereof

Abstract

The application provides a low shrinkage stress UV adhesive, a UV adhesion-reducing film and a preparation method and application thereof, the low shrinkage stress UV adhesive comprises, in mass parts, 20-45 parts of acrylic resin, 10-25 parts of a crosslinking agent, 30-60 parts of a cyclic monomer, 15-30 parts of an active diluent, 2-15 parts of a free radical initiator, 2-15 parts of a cationic initiator and 100-150 parts of a solvent. The application introduces a cationic curing system, and cooperates with specific cyclic monomers and active diluents, so that a semi-interpenetrating polymer network structure is formed after the adhesive is irradiated by UV, the volume shrinkage caused by free radical polymerization is effectively offset, and the solidification shrinkage and residual stress are significantly reduced. The UV adhesion-reducing film prepared from the adhesive has excellent properties such as high initial peeling strength, easy peeling after UV irradiation, no residual glue and no damage to chips, and can meet the low stress and high reliability requirements of the semiconductor packaging field on the cutting film.

Description

Technical Field

[0001] This invention relates to UV adhesive technology, and more particularly to a low-shrinkage-stress UV adhesive, a UV anti-tack film, and their preparation methods and applications. Background Technology

[0002] In the back-end processes of semiconductor manufacturing, wafer dicing and packaging are critical steps. During wafer dicing, a dicing film is used to firmly adhere the wafer to the wafer ring, ensuring that the dicing tools (including precision blades, laser beams, and composite processes combining laser pretreatment followed by blade cutting, or advanced plasma cutting technology, etc.) can accurately cut the wafer into individual chips along the pre-set dicing paths. This prevents chip damage, such as minute displacement, edge chipping, structural breakage, or even debris splashing, caused by vibration or stress during dicing. In subsequent packaging, the dicing film must also facilitate chip removal or transfer, avoiding difficulties in chip detachment or chip damage due to excessive adhesion.

[0003] In recent years, with the rapid development of semiconductor technology towards miniaturization, high-density integration, and high performance, chip sizes have continued to shrink, wafer thicknesses have been continuously reduced, and advanced packaging technologies (such as Fan-out, 3D IC, Chiplet, etc.) have been widely applied. This has placed higher demands on the overall performance of dicing films. Dicing films not only need strong initial adhesion and excellent dicing protection to cope with narrower dicing channels and more fragile thin wafers, but also must have precise and controllable viscosity changes to adapt to high-speed, precise automated packaging processes. Against this backdrop, UV anti-adhesion films have stood out due to their unique integrated "adhesion-dicing-peeling" operation characteristics, becoming the preferred solution in the field of high-precision semiconductor packaging, especially for thin wafers, chiplets, and advanced packaging processes.

[0004] UV adhesive technology was first proposed by European and American companies in the 1970s, initially mainly used in printed circuits and optics. Japanese companies accelerated their technological catch-up in the late 1980s, developing photocurable pressure-sensitive adhesives through modified acrylic resin formulations. They subsequently launched the first commercially available UV anti-tack film, whose core technology lies in the photoinduced anti-tack effect—the adhesive layer's viscosity drops dramatically from 1200-2000g / 25mm to <20g / 25mm after UV irradiation, meeting the high-precision requirements of wafer dicing. Later, as wafer sizes increased from 8 inches to 12 inches, higher demands were placed on the temperature resistance, ductility, and residual adhesive content of UV anti-tack films. Due to their technological advantages, Japanese companies gradually captured over 70% of the global high-end market share and dominated the domestic high-end UV anti-tack film market, almost monopolizing procurement orders from major wafer fabs. Currently, many domestic manufacturers are beginning to challenge the high-end UV anti-tack film market, but due to limitations in UV adhesive technology and processes, most rely on imports from South Korea and Japan.

[0005] The core adhesive system of existing UV anti-adhesion films used in wafer processing mainly consists of acrylic pressure-sensitive adhesive, various oligomers, crosslinking monomers, and photoinitiators. When the UV anti-adhesion film is exposed to UV irradiation, the adhesive strength decreases significantly, making it easier to peel off the diced chip. However, the anti-adhesion principle is actually that the cured adhesive layer shrinks or expands to reduce the peel strength.

[0006] The adhesive layer is mainly composed of acrylic resin. Initially, the monomer molecules have a relatively long van der Waals distance, which is replaced by shorter covalent bond distances within and between polymer chains during the curing process. This results in volume shrinkage, reducing the actual contact area between the adhesive layer and the protected surface, weakening the interfacial adhesion, and thus reducing the adhesion strength to the wafer. This is related to the adhesive bonding mechanism. The interaction mechanism between the wafer and the adhesive layer is mainly physical adsorption, including van der Waals forces and hydrogen bonding. Specifically, it is the interaction between the polar groups of the resin in the adhesive layer and the silanol groups on the wafer surface. However, this will lead to the following problems: (1) Uneven shrinkage or expansion of the adhesive layer will cause local stress concentration, leading to microcracks or damage at the chip edge, and the chip may not be firmly held, fly away, or fall off during pickup; (2) Detachment from the base film will result in residual adhesive due to stress concentration during pickup. Summary of the Invention

[0007] The purpose of this invention is to address the problem of stress concentration, chip breakage, detachment, and residual adhesive caused by adhesive layer volume shrinkage during the curing process of existing UV anti-adhesion films. This invention proposes a low-shrinkage-stress UV adhesive. The UV anti-adhesion film containing this UV adhesive exhibits low shrinkage stress, high adhesion, and easy peeling after UV curing. It ensures that there is no residual adhesive or breakage on the back of the chip after cutting, resulting in reliable packaging quality, stable performance, and the ability to meet the requirements of various packaging processes.

[0008] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is: a low-shrinkage-stress UV adhesive, comprising the following components by weight:

[0010] 20-45 parts acrylic resin;

[0011] 10-25 parts of crosslinking agent;

[0012] 30-60 parts of cyclic monomer;

[0013] 15-30 parts of reactive diluent;

[0014] 2-15 parts of free radical initiator;

[0015] 2-15 parts of cationic initiator;

[0016] Solvent 100-150 parts.

[0017] Furthermore, the acrylic resin is obtained by UV free radical polymerization of a first monomer, a second monomer, and a third monomer.

[0018] Furthermore, the preparation method of the acrylic resin is as follows: the first monomer, the second monomer, the third monomer and the photoinitiator are added to a container protected by nitrogen, and stirred until all materials are completely dissolved; the acrylic resin is finally obtained by irradiation with a UV lamp.

[0019] Furthermore, UV lamp irradiation is used, and the reaction is carried out at 25-90℃ for 1-3 hours.

[0020] Furthermore, the first monomer is an acrylate containing C12 to C30 carbon chains, and the carbon chains can be straight-chain or branched-chain structures.

[0021] Furthermore, the first monomer is preferably one or more of dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, octadecyl acrylate, docosyl acrylate, and isooctadecyl acrylate.

[0022] Furthermore, the first monomer is more preferably dodecyl acrylate.

[0023] Furthermore, the second monomer is an acrylate compound containing a cyclic structure.

[0024] Further, the second monomer is preferably one or more of isobornyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, 1-adamantyl methacrylate, 2-methyl-2-adamantane acrylate, tricyclo[5.2.1.02,6]decanediethanol diacrylate, ethylene glycol dicyclopentenyl ether acrylate, dicyclopentyl methacrylate, and dicyclopentyl acrylate.

[0025] Furthermore, the second monomer is more preferably dicyclopentyl methacrylate.

[0026] Furthermore, the third monomer is a free radical polymerizable vinyl monomer containing an amide group.

[0027] Furthermore, the third monomer is preferably an acrylamide monomer.

[0028] Furthermore, the third monomer is more preferably one or more of N-benzylacrylamide, N-isopropylacrylamide, N-acryloylmorpholine, diacetone acrylamide, N-butoxymethylacrylamide, N-methylacrylamide, acrylamide, and N,N-dimethylacrylamide.

[0029] Furthermore, the third monomer is most preferably N-benzylacrylamide.

[0030] Furthermore, the mass ratio of the first monomer, the second monomer, and the third monomer is 30-60:30-50:10-40.

[0031] Furthermore, the photoinitiator is one or more of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and 2-isopropylthioxanthraphenone.

[0032] Furthermore, the photoinitiator is preferably 1-hydroxycyclohexylphenyl ketone.

[0033] Furthermore, the total mass ratio of the photoinitiator to the monomers is 5-15:1000. The total mass of the monomers is the sum of the first monomer, the second monomer, and the third monomer.

[0034] Furthermore, the preferred total mass ratio of the photoinitiator to the monomer is 10:1000;

[0035] Furthermore, the UV lamp is a UV metal halide lamp, a high-pressure mercury lamp, or an LED lamp. This application does not limit the placement of the UV lamp; however, preferably, the UV lamp is placed around the container, such as on the top, bottom, or sides.

[0036] Furthermore, the molecular weight of the acrylic resin is 50,000-800,000.

[0037] Furthermore, the molecular weight of the acrylic resin is preferably 400,000-600,000.

[0038] Further, the acrylic resin is in the amount of 25-35 parts.

[0039] Furthermore, the crosslinking agent is a multifunctional acrylate compound.

[0040] Further, the crosslinking agent is preferably one or more of 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, bisphenol A epoxy diacrylate, 1,4-butanediol diacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate.

[0041] Furthermore, the crosslinking agent is more preferably pentaerythritol triacrylate.

[0042] Furthermore, the crosslinking agent is 10-20 parts.

[0043] Furthermore, the cyclic monomer is a cyclic monomer capable of undergoing a ring-opening reaction.

[0044] Furthermore, the cyclic monomer is preferably a six-membered ring cyclic carbonate monomer.

[0045] Furthermore, the general formula of the cyclic monomer is shown in formula (I):

[0046]

[0047] (I).

[0048] In formula (I), at least one of R1, R2, and R3 is a group capable of free radical polymerization; the remaining groups are the same or different (substituents that do not affect the ring-opening reaction) and are independently selected from hydrogen, alkyl, alkoxy, ester, and ether groups.

[0049] Furthermore, the group capable of free radical polymerization is one or more of (a) acrylate group, (a) acrylamide group, allyl group, allyl group, vinyl group, or styrene group.

[0050] Further, the cyclic monomer is more preferably one or more of 5-[(allyloxy)methyl]-5-ethyl-1,3-dioxane-2-one and 5-methyl-5-allyloxycarbonyl-1,3-dioxane-2-one.

[0051] Furthermore, the cyclic monomer is present in quantities of 35-50 parts.

[0052] Furthermore, the active diluent is a heterocyclic compound.

[0053] Further, the reactive diluent is preferably one or more of the following: 3-ethyl-3-hydroxymethyloxetane, 3-(benzyloxymethyl)oxetane, 3-phenyl-3-hydroxymethyloxetane, 3,4-epoxytetrahydrofuran, 5-methyl-1,3-dioxane-2-one, 2-acetyl-γ-butyrolactone, 1,5-dioxane-heptane-2-one, 3,4-epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, and (5-ethyl-1,3-dioxane-5-yl)methyl acrylate.

[0054] Furthermore, the reactive diluent is more preferably 3,4-epoxycyclohexylmethyl methacrylate.

[0055] Furthermore, the amount of the reactive diluent is 20-25 parts.

[0056] Further, the free radical initiator is one or more of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0057] Furthermore, the free radical initiator is preferably phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0058] Furthermore, the free radical initiator is 5-10 parts.

[0059] Furthermore, the cationic initiator is one or more of the following: diphenyliodonium hexafluorophosphate, bis(4-tert-butylphenyl)iodohexafluoroantimonate, 4-isopropyl-4'-methyldiphenyliodotetra(pentafluorophenyl)borate, triphenylthionium hexafluorophosphate, triphenylthionium hexafluoroantimonate, and diphenyl-(4-phenylthionium)phenylsulfonium hexafluorophosphate.

[0060] Furthermore, the cationic initiator is preferably diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate.

[0061] Furthermore, the cationic initiator is 5-10 parts.

[0062] Further, the solvent is one or more of ethyl acetate, butyl acetate, methyl isobutyl ketone, acetone, butanone, cyclohexanone, toluene, xylene, n-heptane, cyclohexane, isopropanol, and isopropyl acetate.

[0063] Furthermore, the solvent is preferably toluene.

[0064] Furthermore, the solvent is 115-130 parts.

[0065] Furthermore, the solid content of the low-shrinkage stress UV adhesive is 30%-70%. Unless otherwise specified, all percentages in this document are by weight.

[0066] Another object of the present invention discloses a method for preparing a low-shrinkage-stress UV adhesive, comprising the following steps:

[0067] Acrylic resin, crosslinking agent, cyclic monomer, reactive diluent, free radical initiator, cationic initiator and solvent are mixed and stirred evenly to obtain a low shrinkage stress UV adhesive.

[0068] Furthermore, after mixing and stirring evenly, a degassing treatment is performed to remove air bubbles from the solution.

[0069] Another object of the present invention discloses a UV anti-tack film comprising a release layer, a UV anti-tack adhesive layer and a substrate layer stacked from bottom to top, wherein the UV anti-tack adhesive layer is prepared from the low shrinkage stress UV adhesive.

[0070] Furthermore, the release layer is one or more of polyethylene terephthalate and polyvinyl chloride materials.

[0071] Furthermore, the release layer is preferably made of polyethylene terephthalate.

[0072] Furthermore, the substrate layer is one or more of the following materials: polyolefin, polyethylene terephthalate, polyvinyl chloride, and polyimide.

[0073] Furthermore, the substrate layer is preferably made of polyvinyl chloride.

[0074] Another object of the present invention discloses the application of a low-shrinkage-stress UV adhesive in the field of semiconductor packaging.

[0075] Another object of the present invention discloses a method for preparing a UV anti-adhesion film, comprising the following steps:

[0076] A low-shrinkage-stress UV adhesive is coated onto a release layer, dried to remove the solvent from the low-shrinkage-stress UV adhesive, and then a substrate layer is laminated onto the dried UV adhesive layer to prepare a UV anti-adhesion film.

[0077] Furthermore, the coating method is blade coating, comma roller coating, or trough coating.

[0078] Furthermore, the drying temperature is 100-180℃, and the drying time is 2-10 minutes.

[0079] Furthermore, the coating thickness of the UV adhesive is 10-100 μm.

[0080] Another objective of this invention is to disclose the application of a UV anti-adhesion film in the field of semiconductor packaging.

[0081] The low-shrinkage-stress UV adhesive, UV anti-adhesion film, preparation method, and application of the present invention have the following advantages compared with the prior art:

[0082] 1) The acrylic resin used in the UV adhesive of this invention contains long-chain alkyl side chains, which can penetrate into the micropores on the surface of the adherend to form mechanical interlocking force, ensuring close contact between the adhesive layer and the surface of the adherend, reducing interfacial bubbles or voids, and improving adhesion. At the same time, the ring structure introduced in the acrylic resin side chains has high rigidity and large steric hindrance, forming "rigid support points" at the interface, reducing interfacial slippage of the adhesive layer under stress, and strengthening the mechanical locking effect of the interface. The acrylic resin also contains polar carbonyl groups (C=O) and secondary amine groups, among which the silicon wafer surface oxide layer (SiO2) is rich in hydroxyl groups (-OH). The acrylic resin can form strong hydrogen bonds and dipole-dipole interactions between the adhesive layer and the substrate surface, enhancing interfacial adhesion. In addition, the alkyl substitution in the N-substituted amide can regulate the hydrophobic / hydrophilic balance, so that the adhesive can achieve good wetting and spreading on different surfaces (silicon wafers, glass, metals, plastics, etc.), thereby further improving the adhesion strength of the resin.

[0083] 2) The UV adhesive of the present invention introduces a cationic system including cyclic monomers, reactive diluents and cationic initiators. This system can not only synergistically crosslink with acrylic resin to improve the cohesive strength of the adhesive layer and reduce residual adhesive, but also significantly reduce curing shrinkage and adhesion strength, ultimately reducing stress concentration.

[0084] In this process, cyclic monomers and heterocyclic reactive diluents can undergo ring-opening polymerization under the action of cationic initiators, and the acrylates they contain can participate in free radical polymerization, ultimately forming a semi-interpenetrating polymer network (semi-IPN). In the semi-IPN structure, the two networks interpenetrate each other, restricting the free shrinkage of molecular chains. During the cationic ring-opening process, the molecular chains extend, and the overall volume increases. The low expansion effect of this process cancels out the shrinkage effect of free radical polymerization, which can reduce the shrinkage rate, resulting in less residual stress and a more uniform distribution. At the same time, the formation of the cationic cross-linked network "wraps" the polar groups in the system in the three-dimensional network, reducing the free exposure of polar groups, thereby reducing the adhesion strength with the wafer and ultimately alleviating the stress concentration problem caused by excessive shrinkage of the adhesive layer.

[0085] The low-shrinkage-stress UV adhesive and UV anti-adhesion film of this invention have good application prospects and large-scale promotion potential in the field of semiconductor packaging. Attached Figure Description

[0086] Figure 1 The infrared spectrum of the acrylic resin obtained in Example 1;

[0087] Figure 2 The image shows the film obtained in Comparative Example 14;

[0088] Figure 3 An image of the film obtained in Example 9;

[0089] Figure 4 The image shown is of the adhesive film after peeling off, as obtained in Comparative Example 14.

[0090] Figure 5 This is an image of the adhesive film obtained in Example 9 after peeling. Detailed Implementation

[0091] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0092] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0093] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0094] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0095] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0096] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0097] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0098] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0099] Preparation Examples 1-9

[0100] Preparation Examples 1-9 disclose various acrylic resins prepared using the following methods: First monomer, second monomer, third monomer, and photoinitiator are weighed and added to a nitrogen-protected flask. A UV lamp is placed around the flask (at the top, bottom, or side). The reactants are stirred until all materials are completely dissolved. Then, the UV lamp is turned on, and the reaction temperature is maintained at 76°C. After 3 hours of reaction, the acrylic resin is obtained. The raw materials and formulations used in this method are shown in Table 1.

[0101] Table 1. Raw materials and proportions of acrylic resins used in Examples 1-9

[0102]

[0103] The product obtained in Preparation Example 1 exhibited a distinct molecular weight distribution peak in GPC testing, with its weight-average molecular weight mainly concentrated between 400,000 and 600,000, indicating that the prepared acrylic resin has a high molecular weight level. The acrylic resins obtained in Preparation Examples 2-9 all had weight-average molecular weights between 400,000 and 600,000, with polymer dispersibility index (PDI) of 1.5 to 3 and raw material conversion rates of 85% to 95%.

[0104] Examples 1-8

[0105] Examples 1-8 disclose various low-shrinkage-stress UV adhesives, prepared as follows: Acrylic resin, crosslinking agent, cyclic monomer, reactive diluent, free radical initiator, cationic initiator, and solvent are weighed and mixed evenly. A degassing treatment is then performed to remove air bubbles from the solution, yielding a UV adhesive solution with a solid content of 30%-70%. The raw materials and formulations used in this method are shown in Table 2.

[0106] Table 2 Raw materials and proportions of low-shrinkage stress UV adhesives in Examples 1-8

[0107]

[0108] Comparative Examples 1-7

[0109] Comparative Examples 1-7 disclose various UV adhesives, which are prepared using the same methods as in Example 1. The raw materials and formulations used in this method are shown in Table 3.

[0110] Table 3 Raw materials and proportions of UV adhesives in Comparative Examples 1-7

[0111]

[0112] Examples 9-16 and Comparative Examples 8-14

[0113] Examples 9-16 and Comparative Examples 8-14 disclose various UV anti-adhesion films, including a release layer, a UV anti-adhesion adhesive layer, and a substrate layer stacked from bottom to top. The release layer is made of polyethylene terephthalate (PET release film), and the substrate layer is made of polyolefin. The UV anti-adhesion adhesive layers of Examples 9-16 are prepared using the low-shrinkage stress UV adhesives described in Examples 1-8. The UV anti-adhesion adhesive layers of Comparative Examples 8-14 are prepared using the low-shrinkage stress UV adhesives described in Comparative Examples 1-7.

[0114] Specifically, the preparation method of the UV anti-adhesion film includes the following steps:

[0115] A low-shrinkage-stress UV adhesive was coated onto a release layer to a thickness of 50 μm. The solvent in the low-shrinkage-stress UV adhesive was removed by drying. A substrate layer was then laminated onto the dried UV adhesive layer to prepare a UV anti-adhesive film.

[0116] Using a comma roller coater, a low-shrinkage-stress UV adhesive is evenly coated onto the coating surface of the PET release film. The coated composite film is then placed in an oven, and the drying temperature is set to 120°C for 5 minutes to completely remove the solvent.

[0117] A substrate layer is laminated onto the dried UV adhesive layer to prepare a UV anti-adhesion film.

[0118] Performance testing:

[0119] Figure 1 To prepare the infrared spectrum of the product of Example 1, the results showed that the obtained acrylic resin had an infrared spectrum at 1700 cm⁻¹. - A distinct absorption peak for the ester carbonyl group (C=O) appears near ¹, at 1600 cm⁻¹. - ¹~1500 cm - The presence of a characteristic absorption peak for an amide group near ¹ indicates the successful introduction of ester and amide structures; 2900 cm⁻¹ - ¹ and 2800 cm - ¹ Strong absorption peak near 700 cm⁻¹ - The rocking vibration peak near ¹ indicates the presence of a long-chain alkyl structure in the system; at the same time, the characteristic absorption peak corresponding to the C=C double bond in the monomer is significantly weakened, indicating that the monomer has undergone a polymerization reaction.

[0120] Figure 2 The image shows the film obtained in Comparative Example 14. Figure 3 This is an image of the adhesive film obtained in Example 9. The adhesive layer thickness was 16 μm. Figure 2 and Figure 3 The comparison shows that, compared to Comparative Example 14 which only used a free radical curing system, the adhesive film prepared by the present invention using a free radical-cationic mixed curing system exhibits less volume shrinkage after curing. Further combining... Figure 4 and Figure 5 The comparison results show that the adhesive film prepared using the free radical-cationic mixed curing system leaves virtually no residue after peeling, while the comparative sample exhibits significant residue after peeling. These results indicate that the free radical-cationic mixed curing system helps reduce curing shrinkage and improve peel performance.

[0121] The viscosity of the above-mentioned UV adhesive was measured using an LV-SSR model rotational viscometer, with a detectable viscosity range of 500-10000 cp. The UV adhesive was coated onto a polyethylene terephthalate release film using a coating machine (coating methods include blade coating, comma roller coating, and trough coating). The solvent contained in the adhesive layer was then dried in an oven. After that, a polyvinyl chloride film was laminated on top to finally obtain a UV anti-tack film.

[0122] The test method for peel strength before and after UV curing for performance 1 is as follows:

[0123] Peel strength before UV curing: The UV anti-adhesion film was cut into pieces 25mm wide and 150mm long, and the release layer was removed to expose the UV anti-adhesion layer. Next, the exposed UV anti-adhesion layer (test surface) was adhered to the wafer, and the process was repeated three times using a rubber roller (approximately 100mm wide) to obtain a test sample for peel strength before UV irradiation. The test sample was then placed in an environment with a temperature of 20-25℃ and a humidity of 50-70% for 2 hours. Then, a tensile test was performed in the 180° direction according to GB / T 2792-1998 at a peel speed of 300mm / min to test the peel strength (N / 25mm) of the UV anti-adhesion layer to the wafer.

[0124] UV-cured peel strength: A sample identical to the one used for the UV-cured peel strength test was obtained using the method described above. This sample was then irradiated with ultraviolet light (UV) from the UV-reducing adhesive layer at an irradiation dose of 300 mJ / cm² to obtain the final UV-cured peel strength test sample. The obtained test sample was then subjected to the same procedures as the "UV-cured peel strength test" to measure the peel strength (N / 25 mm) of the UV-reducing adhesive layer against the wafer.

[0125] The test method for the volume shrinkage rate of the adhesive layer in performance 2 is as follows:

[0126] The thickness of the adhesive film was measured using an electric altimeter. A suitable amount of the adhesive film was then directly subjected to UV curing under an irradiation dose of 300 mJ / cm². The thickness of the cured adhesive film was measured again, and the volume shrinkage rate of the adhesive film was finally calculated.

[0127] Performance 3: The test method for whether there is residual adhesive on the wafer surface is as follows:

[0128] Visually inspect the surface of the wafer after UV curing and peel strength test, and evaluate it based on the amount of residual adhesive on the wafer.

[0129] The test method for determining whether the chip is cracked is as follows:

[0130] After the chips have been cured, a suitable amount of chips are taken and observed under an optical microscope to check for cracks on the back of the chips and to make relevant evaluations.

[0131] Table 4 Test Results

[0132]

[0133] Analysis and explanation of test results:

[0134] Based on the above test results, it can be seen that the UV anti-adhesion film prepared by the present invention by introducing a cationic curing system and combining it with a specific cyclic monomer exhibits good peeling performance after curing, with virtually no residue generated, and does not cause significant stress damage to the chip, demonstrating excellent comprehensive performance.

[0135] Specifically, in Example 16, oxobutane monomers were used instead of 5-[(allyloxy)methyl]-5-ethyl-1,3-dioxane-2-one. Since the volume expansion effect of such monomers during cationic ring-opening is limited, it is difficult to effectively offset the volume shrinkage caused by free radical polymerization. This results in a large residual stress in the adhesive layer after curing, leading to a more obvious adhesive residue phenomenon. Furthermore, stress concentration occurs on the back of the chip during the peeling process, ultimately causing the chip to crack.

[0136] Comparative Example 8 uses acrylate monomers with short-chain alkyl side chains. Due to their insufficient molecular chain flexibility and poor wettability to the substrate, the initial tack of the adhesive layer is low, and it is still difficult to form a stable interfacial bond after curing, resulting in residual adhesive.

[0137] Comparative Example 9 did not introduce a cyclic monomer, and the system experienced relatively large volume shrinkage during curing. Although basic adhesion could be achieved, a small amount of residual adhesive remained after curing.

[0138] Comparative Example 10 replaced the cyclic monomer with bisphenol A diglycidyl ether. Although this compound can participate in cationic ring-opening reactions, its ring-opening swelling effect is not obvious, and it cannot participate in free radical polymerization. It is difficult to form a synergistic crosslinking network with acrylic resin, which leads to stress concentration during the curing process and ultimately causes the chip to crack.

[0139] Comparative Example 11 used 1,4-cyclohexanediethanol diethylene ether as a substitute monomer. This compound can only participate in free radical polymerization and cannot form a semi-interpenetrating polymer network with cationic systems. After curing, it has a large volume shrinkage and obvious residue phenomenon.

[0140] Comparative Example 12, due to the lack of cyclic monomers in the system, showed significant volume shrinkage during curing, resulting in severe residue and stress concentration that led to chip breakage.

[0141] Comparative Example 13 did not contain an active diluent, which reduced the overall reaction rate of the system, resulted in insufficient cross-linking, limited reduction in peel strength after curing, and still left residual adhesive.

[0142] Comparative Example 14, due to the absence of a cationic system, relied mainly on free radical polymerization, resulting in significant curing shrinkage and a large amount of residual adhesive.

[0143] In summary, this invention, by rationally introducing cyclic monomers that can simultaneously participate in the reactions of free radicals and cations, enables the system to form a semi-interpenetrating polymer network during the curing process, effectively reducing volume shrinkage and residual stress, and achieving a low-residue, low-stress-damage thickening effect.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-shrinkage-stress UV adhesive, characterized in that, Based on parts by weight, it includes the following components: 20-45 parts acrylic resin; 10-25 parts of crosslinking agent; 30-60 parts of cyclic monomer; 15-30 parts of reactive diluent; 2-15 parts of free radical initiator; 2-15 parts of cationic initiator; Solvent 100-150 parts.

2. The low-shrinkage-stress UV adhesive according to claim 1, characterized in that, The acrylic resin is obtained by UV free radical polymerization of a first monomer, a second monomer, and a third monomer; the first monomer is an acrylate containing a C12 to C30 carbon chain, the second monomer is an acrylate compound containing a cyclic structure, and the third monomer is a free radical polymerizable vinyl monomer containing an amide group.

3. The low-shrinkage-stress UV adhesive according to claim 1, characterized in that, The crosslinking agent is a multifunctional acrylate compound; And / or, the cyclic monomer is a cyclic monomer capable of undergoing a ring-opening reaction; And / or, the active diluent is a heterocyclic compound; And / or, the free radical initiator is one or more of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenylacetone, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and ethyl 2,4,6-trimethylbenzoylphenylphosphonate; And / or, the cationic initiator is one or more of the following: diphenyliodonium hexafluorophosphate, bis(4-tert-butylphenyl)iodohexafluoroantimonate, 4-isopropyl-4'-methyldiphenyliodotetra(pentafluorophenyl)borate, triphenylthionium hexafluorophosphate, triphenylthionium hexafluoroantimonate, and diphenyl-(4-phenylthionium)phenylsulfonium hexafluorophosphate.

4. The low-shrinkage-stress UV adhesive according to claim 1 or 3, characterized in that, The cyclic monomer is a six-membered ring cyclic carbonate monomer.

5. A method for preparing the low-shrinkage stress UV adhesive according to any one of claims 1-4, characterized in that, Includes the following steps: Acrylic resin, crosslinking agent, cyclic monomer, reactive diluent, free radical initiator, cationic initiator and solvent are mixed and stirred evenly to obtain a low shrinkage stress UV adhesive.

6. A UV anti-adhesion film, characterized in that, It comprises a release layer, a UV anti-tack layer and a substrate layer stacked from bottom to top, wherein the UV anti-tack layer is prepared from the low shrinkage stress UV adhesive of any one of claims 1-4.

7. The UV anti-adhesion film according to claim 6, characterized in that, The release layer is made of one or more of polyethylene terephthalate and polyvinyl chloride. And / or, the substrate layer is one or more of the following materials: polyolefin, polyethylene terephthalate, polyvinyl chloride, and polyimide.

8. A method for preparing the UV anti-adhesion film according to claim 6 or 7, characterized in that, Includes the following steps: A low-shrinkage-stress UV adhesive is coated onto a release layer, dried to remove the solvent from the low-shrinkage-stress UV adhesive, and then a substrate layer is laminated onto the dried UV adhesive layer to prepare a UV anti-adhesion film.

9. The method for preparing the UV anti-adhesion film according to claim 8, characterized in that, The drying temperature is 100-180℃, and the drying time is 2-10 minutes.

10. The application of a low-shrinkage-stress UV adhesive according to any one of claims 1-4, or a UV anti-adhesion film according to claim 6 or 7, in the field of semiconductor packaging.

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