A convex ball-planting wafer thinning composite adhesive tape and a preparation method thereof

Abstract

The application relates to the technical field of adhesives, and specifically discloses a convex ball-planting wafer thinning composite adhesive tape and a preparation method thereof. The composite adhesive tape comprises a substrate support layer, a buffer adhesive layer, a UV tack-reducing adhesive layer and a release film layer which are sequentially stacked; the buffer adhesive layer is a solvent-free UV curing acrylate adhesive layer, and the preparation raw materials of the buffer adhesive layer comprise 20-35 parts of aliphatic polyurethane acrylic resin, 30-50 parts of long-chain monofunctional monomer, 3-10 parts of bifunctional monomer, 0.5-1 part of photoinitiator A and 5-15 parts of tackifying resin; the preparation raw materials of the UV tack-reducing adhesive layer comprise 60-80 parts of soft monomer, 5-15 parts of alicyclic hard monomer, 5-10 parts of functional monomer, 0.6-0.8 parts of free radical initiator, 0.5-2 parts of crosslinking agent, 0.7-1 part of photoinitiator B, 5-20 parts of tackifying resin and 80-120 parts of solvent. The total thickness deviation of the wafer after being thinned by the composite adhesive tape prepared by the application is relatively low.

Description

Technical Field

[0001] This application relates to the technical field of adhesives, and more specifically, to a composite tape for wafer thinning with raised ball bearings and a method for preparing the same. Background Technology

[0002] As semiconductor manufacturing technology continues to evolve towards higher density, miniaturization, and higher integration, wafer thinning, as a key process before chip packaging, directly determines the reliability and yield of subsequent packaging processes. The large-scale application of wafers with raised ball structures in advanced packaging places more stringent technical requirements on the protective tape used for temporary wafer fixation during the thinning process, in terms of structural adaptability, performance stability, and process compatibility.

[0003] Currently, temporary fixing tapes for wafer thinning have formed a mature basic application system, which can meet the basic thinning needs of conventional flat wafers. However, for the thinning scenario of ball-mounted wafers, existing products still have significant technical shortcomings. Existing products are mostly developed for flat wafers and are not well adapted to the non-flat surfaces formed by ball-mounting protrusions. They are unable to solve the core problems of local stress concentration and incomplete three-dimensional structure wrapping in the ball-mounting area. At the same time, they have limitations such as high overall application cost and weak adaptability to customized ball-mounting structures. Traditional thinning tapes often suffer from insufficient cushioning capacity of the adhesive layer when facing the wrapping and cushioning requirements caused by the height of the ball-mounting, resulting in pressure damage to the ball-mounting. They may also cause grinding fluid to seep in and contaminate and corrode the wafer due to loose adhesion. In the peeling process, residual adhesive is often left due to insufficient adhesion control precision, which contaminates the wafer and ball-mounting surfaces and affects the processing accuracy and product yield of subsequent processes.

[0004] Patent application CN121160243A discloses a wafer thinning tape with raised balling. The thinning tape includes a substrate film, an anti-adhesion layer, and a release film. The anti-adhesion layer includes, by weight, 60-80 parts of a first polymer network, 15-35 parts of a second polymer network, 0.5-1.5 parts of a thermosetting agent, and 3-5 parts of a photoinitiator. The first polymer network includes, by weight, 70-85 parts of a soft monomer, 5-15 parts of a hard monomer, 5-15 parts of a functional monomer, and a grafted monomer. The second polymer network includes 1,5-pentanediol and fumarate chloride.

[0005] In this technical solution, relying solely on a single anti-adhesion adhesive layer to simultaneously perform multiple functions such as bonding and fixing, anti-adhesion peeling, and deformation buffering cannot simultaneously meet the high adhesion and impermeability requirements of the thinning process and the large deformation wrapping and buffering requirements of the three-dimensional ball-planting structure. When facing protruding ball-planting structures, the ball-planting is easily damaged by pressure due to insufficient deformation buffering capacity of the adhesive layer, or the gaps formed due to loose adhesion may lead to the risk of grinding fluid seepage and wafer corrosion contamination. Summary of the Invention

[0006] To improve the adaptability of raised ball-planted wafer thinning tape to non-flat ball-planted wafers, this application provides a raised ball-planted wafer thinning composite tape and its preparation method.

[0007] In a first aspect, this application provides a composite tape for thinning wafers with raised ball-mounted wafers, employing the following technical solution:

[0008] A composite tape for thinning wafers with raised ball bearings includes a substrate support layer, a buffer adhesive layer, a UV-cured adhesive layer, and a release film layer stacked sequentially. The buffer adhesive layer is a solvent-free UV-cured acrylate adhesive layer, and its raw materials, by weight, include: 20-35 parts of aliphatic polyurethane acrylic resin, 30-50 parts of long-chain monofunctional monomer, 3-10 parts of difunctional monomer, 0.5-1 part of photoinitiator A, and 5-15 parts of tackifying resin.

[0009] The raw materials for preparing the UV-resistant adhesive layer include: 60-80 parts of soft monomer, 5-15 parts of alicyclic hard monomer, 5-10 parts of functional monomer, 0.6-0.8 parts of free radical initiator, 0.5-2 parts of crosslinking agent, 0.7-1 parts of photoinitiator B, 5-20 parts of tackifying resin, and 80-120 parts of solvent.

[0010] This technical solution employs a layered, functionally differentiated composite structure design. The buffer adhesive layer, primarily composed of aliphatic polyurethane acrylic resin, forms a solvent-free UV-curing system with appropriate crosslinking density and excellent deformation recovery capability. During bonding, it fully conforms to the three-dimensional contours of the protruding ball and achieves complete encapsulation. In the thinning process, it effectively disperses localized stress concentration and blocks the penetration path of grinding fluid. The UV-resistant adhesive layer, through a soft-hard monomer copolymer system, imparts high adhesion and interfacial wettability under normal conditions. Furthermore, through a photo / thermal synergistic crosslinking design, it achieves a significant and controllable switch in adhesion before and after UV irradiation, enabling low-stress and gentle peeling after thinning. The two adhesive layers complement and synergistically adapt to the comprehensive requirements of the entire protruding ball wafer thinning process for ball protection, grinding penetration prevention, and clean peeling.

[0011] Preferably, the aliphatic polyurethane acrylate resin is a bifunctional aliphatic polyurethane acrylate resin.

[0012] In this technical solution, the bifunctional aliphatic polyurethane acrylic resin can construct a linear-dominant flexible cross-linked network, while ensuring the uniformity and elastic recovery of the cross-linked network. While maintaining the high elongation at break of the adhesive layer to adapt to the three-dimensional encapsulation of the implanted balls, it avoids permanent deformation of the adhesive layer, significantly improving the dimensional stability of the buffer adhesive layer and the grinding stress dispersion effect.

[0013] Preferably, the long-chain monofunctional monomer is selected from at least one of lauryl acrylate, lauryl methacrylate, and isodecanyl methacrylate.

[0014] In this technical solution, the aforementioned long-chain monofunctional monomers can significantly reduce the glass transition temperature and tensile modulus of the adhesive layer, giving the adhesive layer excellent normal flexibility and deformation fluidity. During low-pressure bonding, it can fully fill the gaps between the ball-planting structures and completely wrap the protruding structures. At the same time, the long-chain structure can balance the flexibility and cohesion of the adhesive layer, avoid creep displacement during grinding, and improve the bonding sealing and ball-planting protection effect.

[0015] Preferably, the bifunctional monomer is selected from at least one of dipropylene glycol diacrylate and ditripropylene glycol diacrylate.

[0016] In this technical solution, the aforementioned bifunctional monomer can reduce the rigidity of the crosslinking network, synergistically regulate the crosslinking density and modulus of the adhesive layer, improve the cohesive force of the adhesive layer while preventing the adhesive layer from becoming brittle and hard, maintain the deformation capacity required for the buffer adhesive layer, and at the same time improve the interfacial bonding stability between the adhesive layer and the substrate and the upper adhesive layer, reducing the risk of interlayer separation.

[0017] Preferably, the buffer layer further includes 1 to 3 parts by weight of a trifunctional monomer.

[0018] Preferably, the trifunctional monomer is selected from either trimethylolpropane triacrylate or pentaerythritol triacrylate.

[0019] In this technical solution, trifunctional monomers can serve as reinforcing nodes in the crosslinking network. A small amount of addition can significantly improve the overall cohesiveness and heat resistance of the adhesive layer, preventing softening of the adhesive layer and wafer displacement due to temperature rise during grinding. At the same time, it forms a gradient crosslinking structure with difunctional monomers, giving the adhesive layer both high deformation capacity and impact resistance. It can more efficiently disperse localized stress concentration during grinding and enhance the protective effect of ball-planting.

[0020] Preferably, the soft monomer is selected from at least one of butyl acrylate and isooctyl acrylate.

[0021] Preferably, the alicyclic hard monomer is selected from at least one of cyclohexyl methacrylate, cyclohexyl acrylate, and dicyclopentyl methacrylate.

[0022] In this technical solution, the rigid alicyclic side chains of the aforementioned alicyclic hard monomers can significantly improve the cohesiveness of the adhesive layer and its heat resistance stability under grinding conditions, ensuring that the adhesive layer does not soften or shift during the thinning process, and maintaining stable adhesion and anti-seepage effects. At the same time, compared with conventional linear or aromatic hard monomers, the alicyclic structure has both rigidity and moderate toughness, which can avoid excessive embrittlement and breakage of the adhesive layer after UV crosslinking, reducing the risk of peeling residue from the root. Moreover, its curing shrinkage rate is lower, which can improve the dimensional stability of the adhesive layer and the uniformity of interface bonding.

[0023] Preferably, the functional monomer is selected from at least one of methacrylic acid, hydroxypropyl acrylate, and hydroxyethyl methacrylate.

[0024] Preferably, the functional monomer comprises acrylate phosphate.

[0025] Preferably, the tackifying resin is selected from at least one of hydrogenated petroleum resin, hydrogenated rosin pentaerythritol ester, and hydrogenated terpene resin.

[0026] In this technical solution, the aforementioned hydrogenated tackifying resin exhibits excellent compatibility with the acrylate system, allowing for precise control of the initial tack and holding power of the adhesive layer. This enhances the interfacial wettability between the tape and the wafer / ball surface, ensuring a tight, gapless bond and blocking the penetration path of the grinding fluid. Simultaneously, the hydrogenated structure possesses excellent weather resistance and heat resistance, maintaining stable performance under temperature variations during the thinning process, with no small molecule substances precipitating out, thus avoiding wafer surface contamination.

[0027] Preferably, the crosslinking agent is hexamethylene diisocyanate trimer.

[0028] Preferably, the substrate support layer is a corona-treated polyethylene terephthalate film.

[0029] Preferably, the thickness of the buffer adhesive layer is 80~500μm.

[0030] Preferably, the thickness of the buffer adhesive layer is 80~150μm.

[0031] Preferably, the thickness of the UV-resistant adhesive layer is 15~50μm.

[0032] Preferably, the thickness of the UV-resistant adhesive layer is 20~40μm.

[0033] Preferably, the buffer adhesive layer further includes 1 to 3 parts by weight of hydrophobic nano-fumed silica.

[0034] In this technical solution, hydrophobic nano-vaporized silica can form a three-dimensional thixotropic network in the buffer adhesive layer. Without interfering with UV curing, the elastic modulus and stress relaxation behavior of the adhesive layer can be precisely controlled, so that the local concentrated stress in the ball-planting area during grinding can be evenly dispersed, significantly improving the flatness of the wafer after thinning.

[0035] Preferably, the buffer layer further comprises 5 to 10 parts by weight of polyether acrylate.

[0036] Preferably, the polyether acrylate is polypropylene glycol diacrylate.

[0037] In this technical solution, the flexible polypropylene glycol segments of polypropylene glycol diacrylate can improve the flexibility and stress relaxation ability of the adhesive layer, enhance the cushioning and protection effect of the ball-coated layer, and at the same time reduce the water sensitivity of the adhesive layer and improve water resistance to block the penetration of grinding fluid. Its diacrylate end groups can provide more crosslinking sites, making the crosslinking network more uniform, taking into account both the elastic recovery and dimensional stability of the adhesive layer, and have excellent compatibility with the host resin and active monomers. The viscosity of the adhesive can be adjusted to suit the coating process.

[0038] Preferably, the photoinitiator A is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (photoinitiator TPO).

[0039] Preferably, the photoinitiator B is 2-hydroxy-2-methyl-1-phenylpropanone (photoinitiator 1173).

[0040] Secondly, this application provides a method for preparing a wafer thinning composite tape with raised ball-mounted wafers, comprising the following steps:

[0041] S1: Mix the aliphatic polyurethane acrylic resin, long carbon chain monofunctional monomer, difunctional monomer and photoinitiator A in the formula amount in the dark, then add the tackifying resin and mix well to obtain the buffer solution.

[0042] S2: Under an inert atmosphere, mix the soft monomer, alicyclic hard monomer, functional monomer, free radical initiator and part of the solvent according to the formula amount, heat to 65~80℃, react for 2~4h, add crosslinking agent, photoinitiator B, tackifying resin and remaining solvent, adjust the solid content, and obtain UV tack-reducing adhesive.

[0043] S3: Apply the buffer adhesive evenly to the corona-treated surface of the substrate support layer, and after pre-curing, obtain the buffer adhesive layer;

[0044] S4: Apply UV anti-tack adhesive evenly to the surface of the buffer adhesive layer, dry it, attach the release film, cure, cut and roll it up to obtain the raised ball-embedded wafer thinning composite tape.

[0045] In this technical solution, a bifunctional adhesive layer is prepared in steps. The buffer adhesive is pre-cured by UV to form a buffer layer that has both an elastic network and interfacial active sites. After the anti-tack adhesive is coated, it is only heat-dried to retain photosensitive activity, so that the anti-tack function is triggered as needed after the wafer thinning is completed.

[0046] Preferably, in step S1, after adding the bifunctional monomer, the step of adding a trifunctional monomer is also included.

[0047] Preferably, in step S1, after adding the aliphatic polyurethane acrylate resin, the step further includes adding hydrophobic nano-fumed silica and / or polyether acrylate.

[0048] In summary, this application has the following beneficial effects:

[0049] This application adopts a layered functional differentiation composite structure design. The buffer adhesive layer adopts a solvent-free UV curing system. Through the gradient compounding of long carbon chain monofunctional monomers and multifunctional crosslinking monomers, the flexibility and cohesive force of the adhesive layer are balanced and controlled, giving it both high deformation encapsulation ability and excellent stress dispersion effect. The UV anti-tack adhesive layer introduces alicyclic hard monomers for copolymerization modification. While ensuring normal adhesion and heat resistance stability under grinding conditions, it effectively reduces the tendency of the adhesive layer to become brittle after UV crosslinking, achieving low-stress, residue-free, and clean peeling. Detailed Implementation

[0050] The present application will be further described in detail below with reference to the embodiments.

[0051] The aliphatic polyurethane acrylic resin is MIRAMER PU210 aliphatic polyurethane acrylate from South Korea, with a purity of 85%~90%, a functionality of 2, and a molecular weight of 2600.

[0052] Hydrophobic nano-fumed silica, Evonik AEROSIL R972, with an average native particle size of 16nm;

[0053] The hydrogenated terpene resin is Yoshida Chemical's hydrogenated terpene resin 115, with an effective ingredient content of 99%, a softening point ≥115℃, and an acid value >1.0mgKOH / g. It was purchased from Shenzhen Yoshida Chemical Co., Ltd.

[0054] The hydrogenated petroleum resin is Exxon Hydrogenated Petroleum Resin 5320, with an effective ingredient content of 99% and a softening point of approximately 124℃. It was purchased from Huizhou Chengtian Polymer Materials Co., Ltd.

[0055] The hydrogenated rosin pentaerythritol ester is Eastman hydrogenated rosin pentaerythritol ester Foral 105-E, with an active ingredient content of 99%, a softening point of 97~102℃, and an acid value of 7~16mgKOH / g. It was purchased from Foshan Ruisheng Plastics Co., Ltd.

[0056] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0057] Example 1

[0058] The method for preparing the raised ball-planted wafer thinning composite tape in this embodiment includes the following steps:

[0059] S1: Preparation of buffer solution

[0060] Under light-protected conditions, 200g of aliphatic polyurethane acrylic resin, 200g of lauryl acrylate, 100g of isodecanyl methacrylate, 30g of dipropylene glycol diacrylate and 5g of photoinitiator TPO were stirred and mixed evenly. Then, 50g of hydrogenated petroleum resin was added and stirred and mixed evenly. Vacuum degassing was performed to obtain a buffer solution.

[0061] S2: Formulation of UV anti-tack adhesive

[0062] Under nitrogen protection, 600g of butyl acrylate, 50g of cyclohexyl methacrylate, 50g of hydroxyethyl methacrylate, 6g of azobisisobutyronitrile and 400g of ethyl acetate were mixed, heated to 70℃ and reacted for 3h. The mixture was then cooled to below 40℃, and 5g of hexamethylene diisocyanate trimer, 7g of photoinitiator 1173, 50g of hydrogenated terpene resin and the remaining 400g of ethyl acetate were added. The mixture was stirred and mixed evenly, and the solid content was adjusted to 40% with ethyl acetate to obtain the UV anti-tack adhesive.

[0063] S3: The buffer adhesive obtained in S1 is uniformly coated onto the surface of a 50μm thick PET film that has undergone corona treatment (surface energy 42mN / m) using a doctor blade coating method, with a coating thickness of 80μm. After coating, it is pre-cured using a 365nm LED light source with an irradiation energy of 300mJ / cm². 2 This allows the gelation rate to reach 45%, resulting in a buffer gel layer.

[0064] S4: The UV anti-tack adhesive obtained in S2 is evenly coated onto the surface of the buffer adhesive layer using a doctor blade coating method. The thickness of the UV anti-tack adhesive layer after drying is controlled to be 20μm. After coating, it is placed in an 80℃ oven to dry for 3min, then heated to 110℃ to dry for 5min. A PE release film with a thickness of 75μm is then laminated and placed in an environment of 40℃ for 48h to cure. After cutting and winding, the raised ball-embedded wafer thinning composite tape is obtained.

[0065] Example 2

[0066] The method for preparing the raised ball-planted wafer thinning composite tape in this embodiment includes the following steps:

[0067] S1: Preparation of buffer solution

[0068] Under light-protected conditions, 350g of aliphatic polyurethane acrylic resin, 20g of hydrophobic nano-fumed silica, 500g of lauryl methacrylate, 50g of tripropylene glycol diacrylate, 50g of dipropylene glycol diacrylate, and 10g of photoinitiator TPO were stirred and mixed evenly. Then, 100g of hydrogenated petroleum resin and 50g of hydrogenated rosin pentaerythritol ester were added, and the mixture was stirred and mixed evenly. The mixture was then degassed under vacuum to obtain a buffer solution.

[0069] S2: Formulation of UV anti-tack adhesive

[0070] Under nitrogen protection, 600g of butyl acrylate, 200g of isooctyl acrylate, 150g of cyclohexyl acrylate, 100g of hydroxypropyl acrylate, 8g of azobisisobutyronitrile and 600g of ethyl acetate were mixed, heated to 80℃ and reacted for 2h. The mixture was then cooled to below 40℃, and 20g of hexamethylene diisocyanate trimer, 10g of photoinitiator 1173, 200g of hydrogenated terpene resin and the remaining 600g of ethyl acetate were added. The mixture was stirred and mixed evenly, and the solid content was adjusted to 40% with ethyl acetate to obtain the UV anti-tack adhesive.

[0071] S3: The buffer adhesive obtained in S1 is uniformly coated onto the surface of a 50μm thick PET film that has undergone corona treatment (surface energy 42mN / m) using a doctor blade coating method, with a coating thickness of 120μm. After coating, it is pre-cured using a 365nm LED light source with an irradiation energy of 300mJ / cm². 2 This allows the gelation rate to reach 45%, resulting in a buffer gel layer.

[0072] S4: The UV anti-tack adhesive obtained in S2 is evenly coated onto the surface of the buffer adhesive layer using a doctor blade coating method. The thickness of the UV anti-tack adhesive layer after drying is controlled to be 30μm. After coating, it is placed in an 80℃ oven to dry for 3min, then heated to 110℃ to dry for 5min. A PE release film with a thickness of 100μm is laminated and placed in an environment of 40℃ for 48h to mature. After cutting and winding, the raised ball-embedded wafer thinning composite tape is obtained.

[0073] Example 3

[0074] The method for preparing the raised ball-planted wafer thinning composite tape in this embodiment includes the following steps:

[0075] S1: Preparation of buffer solution

[0076] Under light-protected conditions, 300g of aliphatic polyurethane acrylic resin, 10g of hydrophobic nano-fumed silica, 400g of isodecanyl methacrylate, 80g of dipropylene glycol diacrylate and 8g of photoinitiator TPO were stirred and mixed evenly. Then, 100g of hydrogenated petroleum resin was added and stirred and mixed evenly. Vacuum degassing was performed to obtain a buffer solution.

[0077] S2: Formulation of UV anti-tack adhesive

[0078] Under nitrogen protection, 700g of isooctyl acrylate, 50g of cyclohexyl acrylate, 50g of dicyclopentyl methacrylate, 50g of hydroxyethyl methacrylate, 25g of methacrylic acid, 7g of azobisisobutyronitrile, and 500g of ethyl acetate were mixed, heated to 65℃, reacted for 4h, cooled to below 40℃, and 15g of hexamethylene diisocyanate trimer, 8g of photoinitiator 1173, 140g of hydrogenated terpene resin, and the remaining 500g of ethyl acetate were added. The mixture was stirred and mixed evenly, and the solid content was adjusted to 40% with ethyl acetate to obtain the UV anti-tack adhesive.

[0079] S3: The buffer adhesive obtained in S1 is uniformly coated onto the surface of a 50μm thick PET film that has undergone corona treatment (surface energy 42mN / m) using a doctor blade coating method, with a coating thickness of 150μm. After coating, it is pre-cured using a 365nm LED light source with an irradiation energy of 300mJ / cm². 2 This allows the gelation rate to reach 45%, resulting in a buffer gel layer.

[0080] S4: The UV anti-tack adhesive obtained in S2 is evenly coated onto the surface of the buffer adhesive layer using a doctor blade coating method. The thickness of the UV anti-tack adhesive layer after drying is controlled to be 40μm. After coating, it is placed in an 80℃ oven to dry for 3min, then heated to 110℃ to dry for 5min. A PE release film with a thickness of 50μm is then laminated and placed in an environment of 40℃ for 48h to cure. After cutting and winding, the raised ball-embedded wafer thinning composite tape is obtained.

[0081] Example 4

[0082] The difference between this embodiment and embodiment 3 is as follows:

[0083] S1: Preparation of buffer solution

[0084] Under light-protected conditions, 300g of aliphatic polyurethane acrylic resin, 15g of hydrophobic nano-fumed silica, 400g of isodecanyl methacrylate, 80g of dipropylene glycol diacrylate, 10g of pentaerythritol triacrylate, and 8g of photoinitiator TPO were stirred and mixed evenly. Then, 100g of hydrogenated petroleum resin was added, and the mixture was stirred and mixed evenly. The mixture was then degassed under vacuum to obtain a buffer solution.

[0085] Everything else is the same as in Example 3.

[0086] Example 5

[0087] The difference between this embodiment and embodiment 4 is that:

[0088] S1: Preparation of buffer solution

[0089] Under light-protected conditions, 300g of aliphatic polyurethane acrylic resin, 15g of hydrophobic nano-fumed silica, 400g of isodecanyl methacrylate, 80g of dipropylene glycol diacrylate, 30g of pentaerythritol triacrylate, and 8.5g of photoinitiator TPO were stirred and mixed evenly. Then, 100g of hydrogenated petroleum resin was added, and the mixture was stirred and mixed evenly. The mixture was then degassed under vacuum to obtain a buffer solution.

[0090] The rest is the same as in Example 4.

[0091] Example 6

[0092] The difference between this embodiment and embodiment 5 is as follows:

[0093] S1: Preparation of buffer solution

[0094] Under light-protected conditions, 300g of aliphatic polyurethane acrylic resin, 15g of hydrophobic nano-fumed silica, 50g of polypropylene glycol 600 diacrylate, 400g of isodecanyl methacrylate, 80g of dipropylene glycol diacrylate, 30g of pentaerythritol triacrylate, and 8.5g of photoinitiator TPO were stirred and mixed evenly. Then, 100g of hydrogenated petroleum resin was added, and the mixture was stirred and mixed evenly. The mixture was then degassed under vacuum to obtain a buffer solution.

[0095] S2: Formulation of UV anti-tack adhesive

[0096] Under nitrogen protection, 700g of isooctyl acrylate, 50g of cyclohexyl acrylate, 50g of dicyclopentyl methacrylate, 50g of hydroxyethyl methacrylate, 25g of methacrylic acid, 10g of 2-hydroxyethyl methacrylate phosphate, 7g of azobisisobutyronitrile, and 500g of ethyl acetate were mixed, heated to 65℃, reacted for 4h, cooled to below 40℃, and 15g of hexamethylene diisocyanate trimer, 8g of photoinitiator 1173, 140g of hydrogenated terpene resin, and the remaining 500g of ethyl acetate were added. The mixture was stirred and mixed evenly, and the solid content was adjusted to 40% with ethyl acetate to obtain the UV anti-tack adhesive.

[0097] The rest is the same as in Example 5.

[0098] Example 7

[0099] The difference between this embodiment and embodiment 6 is that:

[0100] S1: Preparation of buffer solution

[0101] Under light-protected conditions, 300g of aliphatic polyurethane acrylic resin, 15g of hydrophobic nano-fumed silica, 100g of polypropylene glycol 600 diacrylate, 400g of isodecanyl methacrylate, 80g of dipropylene glycol diacrylate, 30g of pentaerythritol triacrylate, and 9g of photoinitiator TPO were stirred and mixed evenly. Then, 100g of hydrogenated petroleum resin was added, and the mixture was stirred and mixed evenly. The mixture was then degassed under vacuum to obtain a buffer solution.

[0102] S2: Formulation of UV anti-tack adhesive

[0103] Under nitrogen protection, 700g of isooctyl acrylate, 50g of cyclohexyl acrylate, 50g of dicyclopentyl methacrylate, 50g of hydroxyethyl methacrylate, 25g of methacrylic acid, 15g of 2-hydroxyethyl methacrylate phosphate, 7g of azobisisobutyronitrile, and 500g of ethyl acetate were mixed, heated to 65℃, reacted for 4h, cooled to below 40℃, and 15g of hexamethylene diisocyanate trimer, 8g of photoinitiator 1173, 140g of hydrogenated terpene resin, and the remaining 500g of ethyl acetate were added. The mixture was stirred and mixed evenly, and the solid content was adjusted to 40% with ethyl acetate to obtain the UV anti-tack adhesive.

[0104] The rest is the same as in Example 6.

[0105] Comparative Example 1

[0106] The difference between this comparative example and Example 1 is as follows:

[0107] S1: Preparation of buffer solution

[0108] Under light-protected conditions, 400g of lauryl acrylate, 100g of isodecyl methacrylate, 30g of dipropylene glycol diacrylate and 5g of photoinitiator TPO were stirred and mixed evenly. Then, 50g of hydrogenated petroleum resin was added and stirred and mixed evenly. Vacuum degassing was performed to obtain a buffer solution.

[0109] Everything else is the same as in Example 1.

[0110] Comparative Example 2

[0111] The difference between this comparative example and Example 1 is as follows:

[0112] S1: Preparation of buffer solution

[0113] Under light-protected conditions, 200g of aliphatic polyurethane acrylic resin, 230g of lauryl acrylate, 100g of isodecyl methacrylate and 5g of photoinitiator TPO were stirred and mixed evenly. Then, 50g of hydrogenated petroleum resin was added and stirred and mixed evenly. Vacuum degassing was performed to obtain a buffer solution.

[0114] Everything else is the same as in Example 1.

[0115] Comparative Example 3

[0116] The difference between this comparative example and Example 1 is as follows:

[0117] S2: Formulation of UV anti-tack adhesive

[0118] Under nitrogen protection, 600g of butyl acrylate, 50g of styrene, 50g of hydroxyethyl methacrylate, 6g of azobisisobutyronitrile and 400g of ethyl acetate were mixed, heated to 70℃ and reacted for 3h. The mixture was then cooled to below 40℃, and 5g of hexamethylene diisocyanate trimer, 7g of photoinitiator 1173, 50g of hydrogenated terpene resin and the remaining 400g of ethyl acetate were added. The mixture was stirred and mixed evenly, and the solid content was adjusted to 40% with ethyl acetate to obtain the UV anti-tack adhesive.

[0119] Everything else is the same as in Example 1.

[0120] Comparative Example 4

[0121] The preparation method of the raised ball-planted wafer thinning composite tape in this comparative example includes the following steps:

[0122] S1: Formulation of UV anti-tack adhesive

[0123] Under nitrogen protection, 600g of butyl acrylate, 50g of cyclohexyl methacrylate, 50g of hydroxyethyl methacrylate, 6g of azobisisobutyronitrile and 400g of ethyl acetate were mixed, heated to 70℃ and reacted for 3h. The mixture was then cooled to below 40℃, and 5g of hexamethylene diisocyanate trimer, 7g of photoinitiator 1173, 50g of hydrogenated terpene resin and the remaining 400g of ethyl acetate were added. The mixture was stirred and mixed evenly, and the solid content was adjusted to 40% with ethyl acetate to obtain the UV anti-tack adhesive.

[0124] S2: The UV anti-tack adhesive liquid obtained in S1 is uniformly coated onto the surface of a PET film with a thickness of 50μm and corona-treated (surface energy 42mN / m) using a doctor blade coating method. The thickness of the UV anti-tack layer after drying is controlled to be 100μm. After coating, it is placed in an oven at 80℃ for 3min, then heated to 110℃ for 7min. A PE release film with a thickness of 75μm is then laminated and placed in an environment at 40℃ for 48h to cure. After slitting and winding, the raised ball-embedded wafer thinning composite tape is obtained.

[0125] Performance testing

[0126] The raised ball-planted wafer thinning composite tapes prepared in Examples 1-7 and Comparative Examples 1-4 were subjected to the following performance tests. The test environment was 23℃±2℃ and 50%±5% relative humidity. The specific test results are shown in Table 1.

[0127] 1. Adhesion: Referring to GB / T 2792-2014, the 180° peel method was used to test the peel force of the samples in Examples 1-7 and Comparative Examples 1-4 before and after UV irradiation, and the presence of residual adhesive was detected simultaneously.

[0128] 2. Total Thickness Deviation (TTV): The sample is attached to the surface of an 8-inch silicon wafer with 50μm high SAC balls, placed on a wafer thinner machine, and thinned to 50μm (original thickness 750μm). The thickness is measured at 21 points at equal intervals along the wafer diameter. The TTV is calculated based on the difference between the maximum and minimum thickness, in μm.

[0129] Table 1. Performance test data of the raised ball-planted wafer thinning composite tapes prepared in Examples 1-7 and Comparative Examples 1-4

[0130]

[0131] Analysis of the performance test data in Table 1 shows that:

[0132] Compared to Example 1, the buffer adhesives in Comparative Examples 1 and 2 lacked aliphatic polyurethane acrylate resin or dipropylene glycol diacrylate, which had virtually no impact on the adhesion before UV treatment. However, the absence of aliphatic polyurethane acrylate resin prevented the buffer adhesive layer from forming an effective elastic network, reducing stress dispersion during grinding. The absence of dipropylene glycol diacrylate resulted in a decrease in crosslinking density and insufficient cohesion of the buffer adhesive layer. Both of these factors led to relatively poor stability of the buffer adhesive layer, resulting in a significant increase in TTV. In Comparative Example 3, although replacing the alicyclic hard monomer with styrene could improve the cohesion of the UV anti-tack adhesive layer to some extent, the aromatic rigid structure of styrene caused a relatively high volume shrinkage rate during polymerization, forming significant shrinkage internal stress within the adhesive layer. This disrupted the uniformity of stress dispersion and flatness control during the thinning process, ultimately leading to a significant increase in TTV. Comparative Example 4 used a single UV anti-tack adhesive layer structure, which, although thicker, could not simultaneously provide buffer protection and adhesion fixation, resulting in poor TTV.

[0133] In Examples 1-3, Examples 2 and 3 introduce hydrophobic nano-vaporized silica into the buffer adhesive layer based on Example 1, which allows the localized stress concentration in the ball-planting area during grinding to be more evenly dispersed, and the wafer flatness to be better maintained, thus directly reflecting the optimization of the TTV index.

[0134] In Examples 4-7, the addition of trifunctional monomers enhanced the integrity of the crosslinked network of the buffer adhesive layer and improved the dimensional stability under grinding conditions; the introduction of polyether acrylate further improved the flexibility and stress relaxation ability of the adhesive layer; and the phosphate functional monomers, by enhancing the chemical bonding between the UV anti-tack adhesive layer and the wafer interface, can reduce the interfacial micro-slippage during the thinning process and achieve continuous optimization of the wafer thinning flatness.

[0135] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A composite tape for thinning wafers with raised ball-mounted wafers, characterized in that, The material comprises a substrate support layer, a buffer adhesive layer, a UV-curable adhesive layer, and a release film layer, which are stacked sequentially. The buffer adhesive layer is a solvent-free UV-curable acrylate adhesive layer, and its raw materials, by weight, include: 20-35 parts of aliphatic polyurethane acrylic resin, 30-50 parts of long-chain monofunctional monomer, 3-10 parts of difunctional monomer, 0.5-1 part of photoinitiator A, and 5-15 parts of tackifying resin. The raw materials for preparing the UV-resistant adhesive layer include: 60-80 parts of soft monomer, 5-15 parts of alicyclic hard monomer, 5-10 parts of functional monomer, 0.6-0.8 parts of free radical initiator, 0.5-2 parts of crosslinking agent, 0.7-1 parts of photoinitiator B, 5-20 parts of tackifying resin, and 80-120 parts of solvent; The aliphatic polyurethane acrylic resin is a bifunctional aliphatic polyurethane acrylic resin; the long carbon chain monofunctional monomer is selected from at least one of lauryl acrylate, lauryl methacrylate, and isodecanyl methacrylate; the bifunctional monomer is selected from at least one of dipropylene glycol diacrylate and ditripropylene glycol diacrylate; the soft monomer is selected from at least one of butyl acrylate and isooctyl acrylate; the alicyclic hard monomer is selected from at least one of cyclohexyl methacrylate, cyclohexyl acrylate, and dicyclopentyl methacrylate; the functional monomer is selected from at least one of methacrylic acid, hydroxypropyl acrylate, and hydroxyethyl methacrylate; photoinitiator A is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; and photoinitiator B is 2-hydroxy-2-methyl-1-phenylpropanone.

2. The raised ball-planted wafer thinning composite tape according to claim 1, characterized in that, The buffer layer also includes 1 to 3 parts by weight of a trifunctional monomer.

3. The raised ball-planted wafer thinning composite tape according to claim 2, characterized in that, The trifunctional monomer is selected from either trimethylolpropane triacrylate or pentaerythritol triacrylate.

4. A method for preparing a wafer thinning composite tape with raised ball-mounted wafers as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Mix the aliphatic polyurethane acrylic resin, long carbon chain monofunctional monomer, difunctional monomer and photoinitiator A in the formula amount in the dark, then add the tackifying resin and mix well to obtain the buffer solution. S2: Under an inert atmosphere, mix the soft monomer, alicyclic hard monomer, functional monomer, free radical initiator and part of the solvent according to the formula amount, heat to 65~80℃, react for 2~4h, add crosslinking agent, photoinitiator B, tackifying resin and remaining solvent, adjust the solid content, and obtain UV tack-reducing adhesive. S3: Apply the buffer adhesive evenly to the corona-treated surface of the substrate support layer, and after pre-curing, obtain the buffer adhesive layer; S4: Apply UV anti-tack adhesive evenly to the surface of the buffer adhesive layer, dry it, attach the release film, cure, cut and roll it up to obtain the raised ball-embedded wafer thinning composite tape.

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