PET (Polyethylene Terephthalate) and ETFE (Ethylene Terephthalate) compounded release film for semiconductor packaging and preparation method thereof

Abstract

The invention discloses a release film for semiconductor packaging based on PET and ETFE compounding and a preparation method of the release film, and belongs to the technical field of film materials, the release film structurally comprises a PET base material layer, an adhesive layer and an ETFE layer which are sequentially arranged, and the adhesive layer is prepared from the following raw materials in parts by mass: 40-60 parts of fluorine-containing acrylate compound; 20 to 30 parts of epoxy modified organic silicon resin; 5 to 10 parts of nano silicon dioxide; 1 to 2 parts of a photoinitiator; wherein the surface of the contact side of the PET base material layer and the adhesive layer is subjected to plasma treatment or corona treatment, and the dyne value is larger than or equal to 50 mN / m; the surface of the side, making contact with the adhesive layer, of the ETFE layer is subjected to fluoridation treatment, and the surface roughness Ra is smaller than or equal to 1 micrometer. The release film has the advantages of controllable release force in a range of 0.1-5N / 25mm, good stability, temperature resistance of 175 DEG C, good organic solvent resistance, and wide application prospect in the field of semiconductor packaging.

Description

Technical Field

[0001] This invention belongs to the field of membrane material technology, specifically relating to a release film for semiconductor packaging based on PET and ETFE composite and its preparation method. Background Technology

[0002] Release film is a crucial auxiliary material in semiconductor packaging. It is primarily used in the molding process, which involves injecting molding material into a mold cavity to cover the chip and internal interconnect structures, ultimately forming a package with mechanical strength, moisture protection, and heat dissipation capabilities. Release film is typically placed between the mold and the molding material, protecting the mold, preventing corrosion, improving demolding efficiency, and reducing defect rates during the molding process.

[0003] Release films in traditional semiconductor packaging are typically made from a single material (such as polyethylene terephthalate (PET), polyethylene (PE), or ethylene-tetrafluoroethylene copolymer (ETFE). However, these materials have limitations in performance, insufficient process adaptability, and decreased reliability. For example, in semiconductor substrate packaging processes, release films need to withstand temperatures above 175°C and peel off without leaving any residue. Pure PET films lack sufficient temperature and chemical resistance, and are prone to deformation at high temperatures, affecting product quality. While ETFE films are heat-resistant, their peel strength is unstable, making it difficult to meet precision requirements. Furthermore, pure ETFE films are expensive, have low mechanical strength, and are difficult to process.

[0004] As mentioned above, single-material release films have some inherent defects, making it difficult to meet the requirements of advanced packaging for high filler adaptability and long-term reliability. Therefore, developing novel multilayer composite and functionalized release films will help promote the development of semiconductor packaging technology.

[0005] Chinese patent document CN116135940A discloses a semiconductor encapsulation tape and its preparation method. The tape comprises a substrate layer, an adhesive layer, and a release film layer sequentially arranged. The adhesive layer includes the following raw materials in parts by weight: 100 parts of high-temperature resistant acrylate polymer, 10-20 parts of epoxy resin, 4-8 parts of modified thermally conductive particles, 1-5 parts of curing agent, 5-10 parts of dibutyl phthalate, and 2-5 parts of γ-(methacryloyloxy)propyltrimethoxysilane. This semiconductor encapsulation tape has good thermal conductivity, as well as high peel strength, heat resistance temperature, and shear strength, and good insulation properties. However, the adhesive layer may pose risks of phase separation and instability, and the use of dibutyl phthalate may cause health hazards such as endocrine disruption.

[0006] Chinese patent document CN109897274A discloses an EFEP film, its preparation method, and its uses. This EFEP film is made from ethylene-tetrafluoroethylene-hexafluoropropylene copolymer (EFEP) and functional additives, with a processing temperature of 140-225℃. The ratio of EFEP to functional additives is 1:0.1-30% by weight, and the functional additives are selected from combinations of PA, PA6, PVDF, and PVC. This EFEP film can be used in flexible solar cell encapsulation, traditional solar cell encapsulation, double-glass solar cell encapsulation, and LED release packaging. However, additives such as PA and PA6 may experience precipitation problems during long-term use. Summary of the Invention

[0007] This invention provides a release film for semiconductor packaging based on PET and ETFE composite. The release film has a three-layer composite structure, including a PET substrate layer, an adhesive layer, and an ETFE layer. The peel force of the release film is controllable in the range of 0.1~5 N / 25 mm, with good stability, temperature resistance up to 175℃, and good resistance to organic solvents. It has broad application prospects in the field of semiconductor packaging.

[0008] The specific technical solution adopted is as follows: A release film for semiconductor packaging based on PET and ETFE composite has a structure comprising a PET substrate layer, an adhesive layer, and an ETFE layer arranged sequentially. The adhesive layer is composed of the following raw materials in parts by weight: fluorinated acrylate compound: 40-60 parts; epoxy modified silicone resin: 20-30 parts; nano silica: 5-10 parts; photoinitiator: 1-2 parts. Fluorinated acrylate compounds have 5 to 10 carbon atoms and contain -CF3 groups; The epoxy-modified silicone resin is obtained by chemically combining silanols hydrolyzed from phenyl and methyl monomers with epoxy resin, specifically selected from epoxy-modified silicone resin 0237.

[0009] The three-layer composite release film developed in this invention combines the performance advantages of PET and ETFE, overcoming the performance limitations of a single film structure. In this release film, the adhesive layer connects the PET substrate layer and the ETFE layer. The components of the adhesive layer work synergistically to endow the adhesive layer with excellent weather resistance, UV resistance, high flexibility, heat resistance, tear resistance, and uniformity, further improving the overall performance of the release film.

[0010] Preferably, in the release film, the thickness of the PET substrate layer is 10–50 μm, the thickness of the adhesive layer is 5–20 μm, and the thickness of the ETFE layer is 30–50 μm.

[0011] Preferably, the particle size of nano-silica is 20–50 nm. Nano-silica helps to enhance the temperature resistance, hardness, and tear resistance of the adhesive layer.

[0012] Preferably, the fluorinated acrylate compound is trifluoroethyl methacrylate, which has 6 carbon atoms and the molecular formula C6H7O2F3.

[0013] Specifically, the photoinitiator is selected from organosilanes, amines, or diimidazoles, etc.

[0014] Preferably, the contact surfaces of the PET substrate layer and the adhesive layer are subjected to plasma treatment or corona treatment, with a dyne value ≥50 mN / m; the contact surfaces of the ETFE layer and the adhesive layer are subjected to fluorination treatment, with a surface roughness Ra≤1 μm. Under the above preferred conditions, the bonding force between the PET substrate layer, the adhesive layer, and the ETFE layer is better, and the failure mechanism changes from traditional interfacial peeling to cohesive fracture within the adhesive layer.

[0015] The present invention also provides a method for preparing the release film for semiconductor packaging based on PET and ETFE composite, comprising the following steps: (1) Take PET film material and perform plasma treatment or corona treatment on one side of its surface to make the dyne value ≥50mN / m; take ETFE film material and perform fluorination treatment on one side of its surface to make the surface roughness Ra≤1μm; (2) Prepare an adhesive solution by mixing 40-60 parts of fluorinated acrylate compound, 20-30 parts of epoxy modified silicone resin, 5-10 parts of nano silica and 1-2 parts of photoinitiator. Apply the adhesive solution to the surface of the PET film that has undergone plasma treatment or corona treatment, and then cover the adhesive solution with the ETFE film so that the fluorinated surface of the ETFE film is in direct contact with the adhesive solution. Then, perform segmented curing and hot pressing to obtain the initial product. (3) The initial product is aged to prepare the release film for semiconductor packaging based on PET and ETFE composite.

[0016] Specifically, the curing process is carried out in two stages, with the curing temperature of the first stage being higher than that of the second stage.

[0017] Preferably, the curing parameters for the first stage are: temperature 80–120℃, time 0.5–2 min; and the curing parameters for the second stage are: temperature 50–80℃, time 0.5–2 min.

[0018] Preferably, the parameters for hot-pressing composite are: temperature 80–120℃, pressure 0.5–5 MPa, and time 5–20 s.

[0019] Preferably, the aging process is carried out at a temperature of 45–60°C for 2–3 days.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The adhesive layer in this invention forms intermolecular forces with the fluorocarbon chains in the ETFE layer through polar groups, thereby enhancing the adhesion to ETFE. Combined with nano-silica, it enhances heat resistance and has significantly better peel strength stability than traditional adhesive layers.

[0021] (2) The present invention adopts a segmented curing combined with hot pressing composite process. The purpose of the first stage of curing is to initially and smoothly start the curing of the adhesive, so that the curing shrinkage of the adhesive is slow and stress is released, the air bubbles are initially discharged, the defects are reduced, and a certain strength is achieved. The second stage of curing will make the adhesive react completely and be fully cured, optimizing the material structure and product performance. Compared with direct one-step curing, segmented curing can better control the curing reaction process, optimize the performance of the adhesive layer, improve uniformity, and reduce its internal defects.

[0022] (3) The release film for semiconductor packaging in this invention comprises a three-layer composite structure of a PET substrate layer, an adhesive layer and an ETFE layer, which helps to overcome the performance limitations of a single film structure.

[0023] (4) The present invention has subjected the contact side surfaces of the PET substrate layer and the adhesive layer to plasma treatment or corona treatment (dyne value ≥50 mN / m); the contact side surfaces of the ETFE layer and the adhesive layer have been subjected to fluorination treatment (surface roughness Ra≤1μm), which helps to enhance the bonding strength. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to the embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically described in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art. Unless otherwise specified, the experimental materials used in the embodiments can be purchased from conventional biochemical reagent companies.

[0025] Specifically, in the following examples and comparative examples, the fluorinated acrylate compound used is trifluoroethyl methacrylate, a commercially available product, and the epoxy-modified silicone resin used is epoxy-modified silicone resin 0237. Epoxy-modified silicone resin 0237 is obtained by chemically combining silanols hydrolyzed from phenyl and methyl monomers with epoxy resin, and is a commercially available product.

[0026] Example 1 Take a PET film and subject one side of its surface to corona treatment so that the dyne value of the PET substrate is 52 mN / m; take an ETFE film and subject one side of its surface to fluorination treatment so that the surface roughness Ra≤1 μm. A binder solution was prepared by mixing 50 parts of a fluorinated acrylate compound, 20 parts of an epoxy-modified silicone resin, 5 parts of nano-silica (particle size 20-50 nm), and 1 part of a photoinitiator organosilane compound (γ-(2,3-epoxypropoxy)propyltrimethoxysilane KH-560). The binder solution was then coated onto the corona-treated surface of a PET film. The treated ETFE film was then placed on top of the binder solution, ensuring direct contact between the fluorinated surface of the ETFE film and the binder solution. Segmented curing was then performed: pre-curing at 120°C for 1 min, followed by final curing at 80°C for 1 min. Hot-pressing was then performed with the following parameters: temperature 100°C, pressure 1 MPa, and time 10 s, yielding the initial product. The initial product was aged at 60°C for 3 days to prepare the release film for semiconductor packaging based on PET and ETFE composite.

[0027] The release film structure for semiconductor packaging based on PET and ETFE composite obtained in this embodiment includes a PET substrate layer, an adhesive layer and an ETFE layer arranged sequentially. The thickness of the PET substrate layer is 25 μm, the thickness of the adhesive layer is 10 μm, and the thickness of the ETFE layer is 35 μm.

[0028] Example 2 Take a PET film and subject one side of its surface to corona treatment so that the dyne value of the PET substrate is 52 mN / m; take an ETFE film and subject one side of its surface to fluorination treatment so that the surface roughness Ra≤1 μm. A binder solution was prepared by mixing 60 parts of a fluorinated acrylate compound, 30 parts of an epoxy-modified silicone resin, 10 parts of nano-silica (particle size 20-50 nm), and 2 parts of a photoinitiator organosilane compound (γ-(2,3-epoxypropoxy)propyltrimethoxysilane KH-560). The binder solution was then coated onto the corona-treated surface of a PET film. The treated ETFE film was then placed on top of the binder solution, ensuring direct contact between the fluorinated surface of the ETFE film and the binder solution. Segmented curing was then performed: pre-curing at 120°C for 1 min, followed by final curing at 80°C for 1 min. Hot-pressing was then performed with the following parameters: temperature 100°C, pressure 1 MPa, and time 10 s, yielding the initial product. The initial product was aged at 60°C for 3 days to prepare the release film for semiconductor packaging based on PET and ETFE composite.

[0029] The release film structure for semiconductor packaging based on PET and ETFE composite obtained in this embodiment includes a PET substrate layer, an adhesive layer and an ETFE layer arranged sequentially. The thickness of the PET substrate layer is 25 μm, the thickness of the adhesive layer is 10 μm, and the thickness of the ETFE layer is 35 μm.

[0030] Example 3 Take a PET film and perform corona treatment on one side of its surface to make the dyne value of the PET substrate 56 mN / m; take an ETFE film and perform surface fluorination treatment on one side of its surface to make the surface roughness Ra≤1 μm. A binder solution was prepared by mixing 60 parts of fluorinated acrylate compound, 30 parts of epoxy-modified silicone resin, 10 parts of nano-silica (particle size 20-50 nm), and 2 parts of photoinitiator organosilane compound (γ-(2,3-epoxypropoxy)propyltrimethoxysilane KH-560). The binder solution was coated onto the corona-treated surface of a PET film, and then the above-treated ETFE film was placed on top of the binder solution, so that the fluorinated surface of the ETFE film was in direct contact with the binder solution. Subsequently, segmented curing was performed, with pre-curing at 120℃ for 1 min and final curing at 80℃ for 1 min. Hot-pressing was then performed with the following parameters: temperature 120℃, pressure 3 MPa, and time 6 s, to obtain the initial product. The initial product was aged at 60°C for 3 days to prepare the release film for semiconductor packaging based on PET and ETFE composite.

[0031] The release film structure for semiconductor packaging based on PET and ETFE composite obtained in this embodiment includes a PET substrate layer, an adhesive layer and an ETFE layer arranged sequentially. The thickness of the PET substrate layer is 25 μm, the thickness of the adhesive layer is 5 μm, and the thickness of the ETFE layer is 35 μm.

[0032] Comparative Example 1 The only difference between this comparative example and Example 1 is that the adhesive layer uses a commercially available conventional polyurethane adhesive (usually a multi-component adhesive composed of hydroxyl-terminated polyurethane prepolymer and polyisocyanate), while the other process parameters are the same as in Example 1.

[0033] Comparative Example 2 The only difference between this comparative example and Example 1 is that the adhesive layer uses a commercially available conventional acrylic adhesive (usually a multi-component adhesive composed of acrylic ester, polyurethane elastomer and peroxide initiator), while the other process parameters are the same as in Example 1.

[0034] Comparative Example 3 The only difference between this comparative example and Example 1 is that the coating adhesive is cured in one step during the production process. The curing parameters for this one step are 120°C and 2 minutes. No segmented curing is performed. All other process parameters are the same as in Example 1.

[0035] Sample Analysis The peel strength, heat shrinkage performance, and organic solvent resistance of the film products prepared by the examples and comparative examples were tested. The results are shown in the table below. The results show that the peel strength of the release film prepared by the method of the present invention is controllable in the range of 0.1~5 N / 25mm, as low as 0.8±0.1 N / 25mm. It has good stability, can withstand temperatures up to 175℃, and has good resistance to organic solvents such as acetone.

[0036] Table 1. Statistical results of membrane product performance obtained in Examples 1-3 and Comparative Examples 1-3

[0037] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A release film for semiconductor packaging based on a PET and ETFE composite, characterized in that, The structure includes a PET substrate layer, an adhesive layer, and an ETFE layer arranged sequentially. The adhesive layer is composed of the following raw materials in parts by weight: fluorinated acrylate compound: 40-60 parts; epoxy modified silicone resin: 20-30 parts; nano silica: 5-10 parts; photoinitiator: 1-2 parts. Fluorinated acrylate compounds have 5 to 10 carbon atoms and contain -CF3 groups.

2. The release film for semiconductor packaging based on PET and ETFE composite as described in claim 1, characterized in that, In the release film, the thickness of the PET substrate layer is 10–50 μm, the thickness of the adhesive layer is 5–20 μm, and the thickness of the ETFE layer is 30–50 μm.

3. The release film for semiconductor packaging based on PET and ETFE composite as described in claim 1, characterized in that, The particle size of nano-silica is 20–50 nm.

4. The release film for semiconductor packaging based on PET and ETFE composite according to claim 1, characterized in that, The fluorinated acrylate compound selected is trifluoroethyl methacrylate, which has 6 carbon atoms.

5. The release film for semiconductor packaging based on PET and ETFE composite according to claim 1, characterized in that, The photoinitiator is selected from organosilanes, amines, or diimidazoles.

6. The release film for semiconductor packaging based on PET and ETFE composite according to claim 1, characterized in that, The contact surfaces of the PET substrate layer and the adhesive layer were subjected to plasma treatment or corona treatment, with a dyne value ≥50 mN / m; the contact surfaces of the ETFE layer and the adhesive layer were subjected to fluorination treatment, with a surface roughness Ra≤1 μm.

7. The method for preparing a release film for semiconductor packaging based on a PET and ETFE composite according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Take PET film material and perform plasma treatment or corona treatment on one side of its surface to make the dyne value ≥50 mN / m; take ETFE film material and perform fluorination treatment on one side of its surface to make the surface roughness Ra≤1 μm; (2) Prepare an adhesive solution by mixing 40-60 parts of fluorinated acrylate compound, 20-30 parts of epoxy modified silicone resin, 5-10 parts of nano silica and 1-2 parts of photoinitiator. Apply the adhesive solution to the surface of the PET film material that has undergone plasma treatment or corona treatment. Then cover the adhesive solution with the ETFE film material so that the fluorinated surface of the ETFE film material is in direct contact with the adhesive solution. Then perform segmented curing and hot pressing to obtain the initial product. (3) The initial product is aged to prepare the release film for semiconductor packaging based on PET and ETFE composite.

8. The method for preparing a release film for semiconductor packaging based on a PET and ETFE composite according to claim 7, characterized in that, The curing process is carried out in two stages, with the curing temperature of the first stage being higher than that of the second stage.

9. The method for preparing a release film for semiconductor packaging based on PET and ETFE composite according to claim 8, characterized in that, The curing parameters for the first stage are: temperature 80–120℃, time 0.5–2 min; the curing parameters for the second stage are: temperature 50–80℃, time 0.5–2 min.

10. The method for preparing a release film for semiconductor packaging based on a PET and ETFE composite according to claim 7, characterized in that, The parameters for hot-pressing composite are: temperature 80–120℃, pressure 0.5–5 MPa, and time 5–20 s.

11. The method for preparing a release film for semiconductor packaging based on a PET and ETFE composite according to claim 7, characterized in that, The aging process is carried out at a temperature of 45–60℃ for 2–3 days.

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