An epoxy encapsulation film for filter modules, its preparation method and application

Abstract

This invention provides an epoxy encapsulation film for filter modules, its preparation method, and its application. The epoxy encapsulation film comprises the following components by weight percentage: 30%–40% silica, 24%–42% epoxy resin, 11%–25% phenoxy resin, 2%–5% core-shell rubber, 8%–14% phenolic curing agent, and 0.4%–0.6% imidazole accelerator. The epoxy resin is composed of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin. The molecular weight of the phenoxy resin is 52,000–57,000. The epoxy encapsulation film for filter modules prepared by this invention through a specific formulation ratio has excellent flexibility and mechanical properties, which can improve the reliability of filter module encapsulation, simplify the filter module encapsulation process, shorten the process cycle, and reduce production costs.

Description

Technical Field

[0001] This invention belongs to the field of filter packaging technology, and specifically relates to an epoxy encapsulation film for filter modules, its preparation method, and its application. Background Technology

[0002] Because the functional area on the surface of the filter chip requires a cavity to ensure the normal operation of the filter element, while other components in the module do not need a cavity structure and can be directly encapsulated, the current packaging of filter modules usually involves first performing wafer-level packaging on the filter to form a cavity structure, and then performing secondary packaging on other non-filter components. This method increases the packaging cycle, reduces production efficiency, and the first wafer-level packaging will affect the thickness of the subsequent filter module packaging, increasing the packaging process and difficulty.

[0003] Existing technologies typically encapsulate filter modules using a coating process: first, the filter module is coated to create a cavity for the filter, and non-filter components that do not require a cavity also form cavities. After coating, the film is cured, and then a laser is used to burn open the film on the non-filter components before filling them with molding compound. However, because the filter and non-filter components vary in size and height, this places high demands on the performance of the coating film. Poor coating results in gaps due to poor adhesion, leading to poor product sealing and reduced reliability. Alternatively, the film may break during coating, causing subsequent molding compound to enter the filter cavity and cause failure. Therefore, there is an urgent need for an epoxy encapsulation film suitable for filter modules that can effectively encapsulate them.

[0004] In other words, how to provide an epoxy encapsulation film for filter modules, using polyurethane-modified epoxy resin and low-modulus flexible epoxy resin as the matrix resin, and combining phenyloxy resin and core-shell rubber to improve the toughness and strength of the epoxy encapsulation film, thereby simplifying the encapsulation process of the filter module and improving the encapsulation reliability, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an epoxy encapsulation film for filter modules, its preparation method, and its application, so as to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the first aspect of the present invention provides an epoxy encapsulation film for a filter module, wherein the epoxy encapsulation film comprises, by weight percentage: 30%–40% silica, 24%–42% epoxy resin, 11%–25% phenoxy resin, 2%–5% core-shell rubber, 8%–14% phenolic curing agent, and 0.4%–0.6% imidazole accelerator; wherein the epoxy resin is composed of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin; and wherein the molecular weight of the phenoxy resin is 52,000–57,000.

[0007] In the first aspect, the polyurethane-modified epoxy resin has a mass percentage of 8% to 16%, and the low-modulus flexible epoxy resin has a mass percentage of 16% to 28%.

[0008] In the first aspect, the epoxy equivalent of the polyurethane-modified epoxy resin is 230-260 g / eq; and the epoxy equivalent of the low-modulus flexible epoxy resin is 360-390 g / eq.

[0009] In the first aspect, the silica has a particle size D50 of 4.5 μm and a D99 of 10 μm.

[0010] In the first aspect, the hydroxyl equivalent of the phenolic curing agent is 100-110 g / eq.

[0011] In the first aspect, the imidazole accelerator includes at least one of 2-ethyl-4-methylimidazole and 2-phenyl-4-methylimidazole.

[0012] In the first aspect, the core-shell rubber includes at least one of LP-4100 and LP-4200.

[0013] The second aspect of the present invention provides a method for preparing an epoxy encapsulation film for a filter module as described in the first aspect. The preparation method includes: mixing each component according to its respective mass percentage, grinding the mixed components into a gel using a bead mill, obtaining a slurry by vacuum degassing, coating the slurry onto a base film using a coating machine, drying and removing the base film to obtain an epoxy encapsulation film; the thickness of the epoxy encapsulation film is 20-50 μm.

[0014] A third aspect of the present invention provides a method for encapsulating a filter module. The encapsulation method includes: mixing, bead milling, and vacuum degassing the components of the epoxy encapsulation film for the filter module described in the first aspect to obtain a mixed slurry; coating the mixed slurry onto a base film and drying it to obtain an epoxy encapsulation film on the base film; and placing a silicone pad on the surface of the epoxy encapsulation film to cover the top and sides of the filter module and adhere it to the substrate below by vacuum hot pressing to complete the encapsulation of the filter module; the conditions for vacuum hot pressing include: pressure of 0.3–0.9 MPa, temperature of 80–120°C, and time of 60–120 s.

[0015] The fourth aspect of the present invention provides an application of the epoxy encapsulation film for filter modules described in the first aspect in filter module packaging.

[0016] Beneficial effects:

[0017] This invention provides an epoxy encapsulation film for filter modules, comprising the following components by weight percentage: 30%–40% silica, 24%–42% epoxy resin, 11%–25% phenylene oxide resin, 2%–5% core-shell rubber, 8%–14% phenolic curing agent, and 0.4%–0.6% imidazole accelerator. The epoxy resin is composed of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin. The molecular weight of the phenylene oxide resin is 52,000–57,000. By using an epoxy resin composed of a mixture of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin as the matrix material, it exhibits good flexibility and elasticity, can adapt to large deformations without easily breaking, and utilizes the structural characteristics of phenylene oxide resin to penetrate the matrix material, further improving the toughness and strength of the epoxy encapsulation film. At the same time, the core-shell rubber, with its hard core and soft shell characteristics, is mixed with the matrix material to form a "silver particle-nail-anchor" mechanism, effectively inhibiting crack propagation and thus improving the toughening effect of the material. This invention prepares an epoxy encapsulation film for filter modules through a specific formulation ratio. It has excellent flexibility and mechanical properties, which can improve the reliability of filter module encapsulation, simplify the encapsulation process of filter modules, shorten the process cycle, and reduce production costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This invention provides a schematic diagram illustrating the application of an epoxy encapsulation film for filter modules in filter module packaging.

[0020] Figure 2 This is a schematic diagram of the filter module packaging failure in Comparative Example 1 of this invention;

[0021] Figure 3 This is a schematic diagram of the filter module packaging failure in Comparative Example 2 of this invention;

[0022] Figure label:

[0023] 1. Substrate; 2. Filter components; 3. Non-filter components; 4. Epoxy encapsulation film; 5. Cavity; 6. Molding compound. Detailed Implementation

[0024] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0025] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or by existing methods.

[0027] This application provides an epoxy encapsulation film for a filter module, wherein the epoxy encapsulation film comprises the following components by weight percentage: 30%–40% silica, 24%–42% epoxy resin, 11%–25% phenoxy resin, 2%–5% core-shell rubber, 8%–14% phenolic curing agent, and 0.4%–0.6% imidazole accelerator; the epoxy resin is composed of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin; the phenoxy resin has a molecular weight of 52,000–57,000.

[0028] Specifically, the present invention provides an epoxy encapsulation film for filter modules, comprising the following components by weight percentage: 30%–40% silica, 24%–42% epoxy resin, 11%–25% phenylene oxide resin, 2%–5% core-shell rubber, 8%–14% phenolic curing agent, and 0.4%–0.6% imidazole accelerator; the epoxy resin is composed of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin; the molecular weight of the phenylene oxide resin is 52,000–57,000; by using an epoxy resin composed of a mixture of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin as the matrix material, it has good flexibility and elasticity, can adapt to large deformations without easily breaking, and utilizes the structural characteristics of phenylene oxide resin to penetrate the matrix material, further improving the toughness and strength of the epoxy encapsulation film; at the same time, combined with the characteristics of the core-shell rubber, which has a hard core and a soft shell, it is mixed with the matrix material to form a "silver particle-nail-anchor" mechanism, effectively inhibiting crack propagation, thereby improving the toughening effect of the material. This invention prepares an epoxy encapsulation film for filter modules through a specific formulation ratio. It has excellent flexibility and mechanical properties, which can improve the reliability of filter module encapsulation, simplify the encapsulation process of filter modules, shorten the process cycle, and reduce production costs.

[0029] It should be further explained that, in the prior art, for epoxy resin systems to play a toughening role, it is necessary to induce the formation of crazing on the one hand, and on the other hand, to have the ability to prevent the propagation of crazing. Unmodified epoxy resin matrix is ​​prone to stress concentration and rapid failure at the sharp crack ends of brittle resin. Therefore, this invention uses polyurethane modified epoxy resin and low-modulus flexible epoxy resin as matrix materials, and combines phenyl oxy resin and core-shell rubber to improve the flexibility and film strength of the material. In addition, the use of phenyl oxy resin can improve the impact resistance of the epoxy encapsulation film after curing, so as to facilitate processing.

[0030] In some possible embodiments, the polyurethane-modified epoxy resin has a mass percentage of 8% to 16%, and the low-modulus flexible epoxy resin has a mass percentage of 16% to 28%.

[0031] In some possible embodiments, the epoxy equivalent of the polyurethane-modified epoxy resin is 230–260 g / eq; and the epoxy equivalent of the low-modulus flexible epoxy resin is 360–390 g / eq.

[0032] In this invention, polyurethane-modified epoxy resin and low-modulus flexible epoxy resin are selected as matrix materials to provide basic flexibility and film strength for epoxy encapsulation film. Specifically, the preferred polyurethane-modified epoxy resin is EPU-133L, and the preferred low-modulus flexible epoxy resin is AER-9000.

[0033] In some possible embodiments, the silica has a particle size D50 of 4.5 μm and a D99 of 10 μm.

[0034] Furthermore, silica is used as a filler, and the thermal expansion coefficient of the epoxy encapsulation film is reduced by controlling the particle size of silica, so as to improve the adhesion to the filter components and thus prevent foreign objects from entering the cavity of the filter components and affecting the packaging reliability of the filter module.

[0035] In some possible embodiments, the hydroxyl equivalent of the phenolic curing agent is 100-110 g / eq.

[0036] In some possible embodiments, the imidazole accelerator includes at least one of 2-ethyl-4-methylimidazole and 2-phenyl-4-methylimidazole.

[0037] In this application, phenolic curing agents are selected to improve the shelf life of epoxy encapsulation films, and imidazole accelerators are used to adjust the curing temperature and curing speed of epoxy encapsulation films.

[0038] In some possible embodiments, the core-shell rubber includes at least one of LP-4100 and LP-4200.

[0039] Specifically, by utilizing the characteristics of the "hard core" and "soft shell" of the core-shell rubber, the flexibility and strength of the epoxy encapsulation film are improved. This allows the epoxy encapsulation film to fit tightly with the filter components during the filter module encapsulation process, while also preventing the epoxy encapsulation film from breaking under external force. This effectively prevents foreign objects from entering the filter components and improves the reliability of the encapsulation.

[0040] Based on a general inventive concept, this application also provides a method for preparing an epoxy encapsulation film for a filter module as described in the first aspect. The preparation method includes: mixing each component according to its respective mass percentage, grinding the mixed components into a gel using a bead mill, obtaining a slurry by vacuum degassing, coating the slurry onto a base film using a coating machine, and removing the base film after drying to obtain an epoxy encapsulation film; the thickness of the epoxy encapsulation film is 20-50 μm.

[0041] Based on a general inventive concept, this application also provides a method for encapsulating a filter module. The encapsulation method includes: stirring and mixing the components of the epoxy encapsulation film for the filter module described in the first aspect, bead milling, and vacuum degassing to obtain a mixed slurry; coating the mixed slurry onto a base film and drying it to obtain an epoxy encapsulation film on the base film; placing a silicone pad on the surface of the epoxy encapsulation film, and then covering the top and sides of the filter module and bonding it to the substrate below by vacuum hot pressing to complete the encapsulation of the filter module; the conditions for vacuum hot pressing include: pressure of 0.3–0.9 MPa, temperature of 80–120°C, and time of 60–120 s.

[0042] Specifically, this invention mixes the raw materials according to a specific formula ratio, and after bead milling and vacuum degassing, obtains a uniformly dispersed slurry. This slurry is then coated onto a base film and dried to form an epoxy encapsulation film. The epoxy encapsulation film is then placed over the filter module to be encapsulated, and the base film is removed. A silicone pad is then applied for vacuum hot pressing of the epoxy encapsulation film. Utilizing the excellent tensile strength and elongation of the epoxy encapsulation film, it is tightly bonded to the top and sides of the filter module, completing the encapsulation of the filter module. Furthermore, epoxy encapsulation films of different thicknesses can be prepared according to different usage environments.

[0043] Based on a general inventive concept, this application also provides the application of the epoxy encapsulation film for filter modules described in the first aspect in filter module packaging.

[0044] Specifically, the epoxy encapsulation film provided in this invention can be applied to filter module encapsulation. Please refer to [link / reference]. Figure 1 A complete filter module includes several filter components 2 and several non-filter components 3. The filter components 2 and non-filter components 3 are indirectly mounted on the substrate 1 through copper pillars or solder balls. An epoxy encapsulation film 4 is applied to the filter components 2 and non-filter components 3 by vacuum hot pressing and is then bonded to the substrate 1. After vacuum hot pressing, the epoxy encapsulation film 4 attached to the non-filter components 3 is burned off by laser, thus forming a cavity 5 only between the filter components 2 and the substrate 1. Finally, the filter module is encapsulated with molding compound 6, which covers the epoxy encapsulation film 4, the area around the non-filter components 3, and between the copper pillars, preventing the molding compound 6 from entering the cavity 5 and improving the reliability of the filter module encapsulation.

[0045] It should be added that the filter component 2 needs to form a cavity 5 structure with the substrate 1, and there must be no foreign objects in the cavity 5 in order to work properly; while the non-filter component 3 does not need a cavity structure and can also work, so it needs to be filled and sealed with molding compound 6.

[0046] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0047] The components of the raw materials in Examples 1-4 and Comparative Examples 1-6 of this application, expressed as mass percentages in Table 1-2, are shown below:

[0048] Table 1. Distribution ratio of raw materials in the comparative example

[0049]

[0050] Table 2. Distribution ratio of raw materials in each component in the examples

[0051]

[0052] The epoxy encapsulation films provided in Examples 1-5 and Comparative Examples 1-6 were subjected to performance tests. The specific test procedures are as follows:

[0053] 1. Membrane tensile strength and elongation at break: Cut a 10mm×50mm membrane material, peel off the light strip, stick the two ends of the strip with tape, clamp the tape at both ends of the universal testing machine, peel off the heavy strip, and test the tensile strength and elongation at break of the membrane.

[0054] 2. Storage modulus: Reference standard: ASTM E2254-2018. Take a sample that has been completely cured at 100℃ / 1H+175℃ / 2H. Prepare the test sample with dimensions of 55mm×10mm×2mm. Measurement mode: dual cantilever mode, vibration frequency: 1Hz, amplitude: 10μm, heating rate: 5℃ / min. The storage modulus is taken as the value at 25℃ and 150℃.

[0055] 3. Glass transition temperature Tg: Reference standard: ASTM E2254-2018. The sample was completely cured at 100℃ / 1H+175℃ / 2H. The size of the test sample was 55mm×10mm×2mm. DMA was used for measurement. Measurement mode: dual cantilever mode, vibration frequency: 1Hz, amplitude: 10μm, heating rate: 5℃ / min.

[0056] 4. Coefficient of Thermal Expansion: Method: Reference standard: ASTM E831-2019. Samples fully cured at 100℃ / 1H + 175℃ / 2H were used, and the sample dimensions were prepared as 5mm × 5mm × 2mm. The coefficient of thermal expansion was tested using TMA (compression mode). TMA parameter settings: Preload force: 0.05N; First scan: room temperature - 250℃ (heating rate 10℃ / min); Second scan: room temperature - 250℃ (heating rate 10℃ / min); data from the second heating segment were collected. The coefficient of thermal expansion CTE1 / 2 was taken at temperatures of 40℃-70℃ and 180℃-210℃, respectively.

[0057] 5. Silicon / copper sheet adhesion test method: Transfer a 2mm×2mm film (thickness 20-50μm) between two silicon / copper sheets, cure at 100℃ / 1H+175℃ / 2H, and test the shear bond strength using a universal tensile tester.

[0058] The test results are shown in Table 3 below:

[0059] Table 3 Test Results

[0060]

[0061] As can be seen from the table above:

[0062] (1) Comparative Example 1 did not use low-modulus flexible epoxy resin, and the epoxy encapsulation film prepared had a smaller elongation at break, resulting in a low elongation rate of the epoxy encapsulation film. During the encapsulation process, the epoxy encapsulation film could not adhere to the substrate and could not be bonded to the filter components and the substrate at a 90° angle, causing the filter module encapsulation to fail (e.g. Figure 2 As shown), Comparative Example 2, which did not use polyurethane-modified epoxy resin EPU-133L, produced an epoxy encapsulation film with low tensile strength. This film ruptured during the encapsulation process, failing to prevent the molding compound from penetrating the cavity during subsequent molding, leading to filter module encapsulation failure (e.g., ...). Figure 3 (as shown)

[0063] (2) The amount of silica added in Comparative Example 3 exceeds the range specified in this application. The content of polyurethane modified epoxy resin and low modulus flexible epoxy resin in Comparative Example 4 is lower than the range specified in this application. The content of silica, polyurethane modified epoxy resin and low modulus flexible epoxy resin in Comparative Example 5 all exceed the range specified in this application. This results in a high coefficient of thermal expansion and low adhesion between silicon wafer and copper sheet in the prepared epoxy encapsulation film, which cannot meet the encapsulation requirements of the filter module.

[0064] (3) Comparative Example 6 uses flexible liquid epoxy resin YX-7400N to replace low modulus flexible epoxy resin AER-9000. Its film tensile strength is low, and its film elongation at break is not high enough. There will be film breakage during vacuum pressing. In addition, its expansion coefficient is high, TG is low, and the adhesion between silicon wafer and copper sheet is also low, which has a significant impact on the reliability of subsequent filter module packaging.

[0065] (4) Examples 1-5 use a mixture of low modulus flexible epoxy resin and polyurethane modified epoxy resin. The amount of silica, phenoxy resin and core-shell rubber added is within the optimal range of use, showing good elongation at break and strength of the film material, which can completely adhere to the filter components during the vacuum pressing process without film breakage. At the same time, its low energy storage modulus can prevent the molding material from invading the cavity of the filter components during the subsequent liquid molding process. Its low coefficient of expansion, high TG and adhesion of silicon wafer and copper sheet are the basis for improving the reliability of filter module packaging.

[0066] In summary, by using epoxy encapsulation films configured within the specific range of this application for each component of the raw materials, and by selecting specific polyurethane-modified epoxy resins and low-modulus flexible epoxy resins, epoxy encapsulation films with excellent flexibility and elongation can be obtained. This allows for complete bonding with filter components and the formation of cavities during the filter module encapsulation process, preventing foreign matter from penetrating into the cavities and improving the reliability and lifespan of the encapsulation. Furthermore, epoxy encapsulation films of different thicknesses can be prepared to suit the encapsulation of different types of filter modules.

[0067] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0068] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0069] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An epoxy encapsulation film for a filter module, characterized in that, The epoxy encapsulation film comprises, by weight percentage: 30%–40% silica, 24%–42% epoxy resin, 11%–25% phenoxy resin, 2%–5% core-shell rubber, 8%–14% phenolic curing agent, and 0.4%–0.6% imidazole accelerator; the epoxy resin is composed of polyurethane-modified epoxy resin and low-modulus flexible epoxy resin; the phenoxy resin has a molecular weight of 52,000–57,000. The polyurethane-modified epoxy resin has a mass percentage of 8% to 16%, and the low-modulus flexible epoxy resin has a mass percentage of 16% to 28%. The silica has a particle size D50 of 4.5 μm and a D99 of 10 μm. The hydroxyl equivalent of the phenolic curing agent is 100-110 g / eq; The imidazole accelerator includes at least one of 2-ethyl-4-methylimidazol and 2-phenyl-4-methylimidazol; The core-shell rubber includes at least one of LP-4100 and LP-4200; The polyurethane-modified epoxy resin is of type EPU-133L, and the low-modulus flexible epoxy resin is of type AER-9000.

2. A method for preparing an epoxy encapsulation film for a filter module as described in claim 1, characterized in that, The preparation method includes: The components are stirred and mixed according to their respective mass percentages. The mixed components are then ground into a gel-like substance using a bead mill. The mixture is then degassed under vacuum to obtain a slurry. The slurry is then coated onto a base film using a coating machine. After drying, the base film is removed to obtain an epoxy encapsulation film. The thickness of the epoxy encapsulation film is 20-50 μm.

3. A method for packaging a filter module, characterized in that, The encapsulation method includes: The components of the epoxy encapsulation film for filter modules described in claim 1 are stirred, mixed, bead-milled, and vacuum degassed to obtain a mixed slurry. The mixed slurry is coated onto a base film and then dried to obtain an epoxy encapsulation film on the base film. A silicone pad is disposed on the surface of the epoxy encapsulation film, so that the epoxy encapsulation film is covered on the top and sides of the filter module and bonded to the substrate below by vacuum hot pressing to complete the encapsulation of the filter module; the conditions of the vacuum hot pressing include: pressure of 0.3 to 0.9 MPa, temperature of 80 to 120°C, and time of 60 to 120 seconds.

4. The application of the epoxy encapsulation film for filter modules as described in claim 1 in filter module packaging.

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