Chip-scale filter packaging film, filter chip and preparation methods therefor

Abstract

A chip-scale filter packaging film, a filter chip, and preparation methods therefor. The packaging film comprises the following components in percentage by mass: 55-70% of silicon dioxide, 14-24% of an epoxy resin, 15-20% of a phenoxy resin, 1-2.5% of a curing agent, 0.5-1.2% of a promoter, and 0.3-0.9% of a coloring agent, wherein the epoxy resin is composed of a polyurethane-modified bisphenol A epoxy resin and a tetrafunctional epoxy resin, and the molecular weight of the phenoxy resin is 50,000-150,000. By selecting silicon dioxide having a large particle size and a phenoxy resin having a high molecular weight and combining a polyurethane-modified bisphenol A epoxy resin with a tetrafunctional group epoxy resin, the packaging film has certain fluidity under vacuum hot-pressing conditions, thereby ensuring the wrapping of the peripheries of the filter chip and preventing adhesive seepage into a cavity function area; in addition, the packaging film can reduce the packaging size of a filter, simplify the method of packaging of the filter, reduce the packaging cost, improve the packaging efficiency and packaging yield, and better satisfy the need for miniaturized packaging in the future.

Description

Chip-level filter packaging film, filter chip and preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of filter packaging, and in particular relates to a chip-level filter packaging film, a filter chip and a preparation method thereof. Background Art

[0002] With the rapid development of communication equipment, higher requirements are being placed on filter packaging technology. Filters are important semiconductor devices, and filter packaging is the process of sealing the filter's functional area to form a cavity to protect the filter from the external environment.

[0003] Due to the small size of filter components, the packaging process cost is high. For example, a barrier is set to form a closed cavity around the functional surface of the filter chip to prevent the entry of plastic packaging material; or the functional surface of the filter is bonded to a deep cavity made on the shell by parallel welding of the ceramic shell, and the air is replaced by nitrogen to ensure that the device is not contaminated. However, this packaging method is large in size and has low processing efficiency; or a film is used to isolate the external plastic packaging material to ensure that the functional area of ​​the filter forms a cavity and is not contaminated. This requires the covering film to have excellent flexibility and adhesion, and will also increase the packaging size of the filter.

[0004] Currently, the packaging method for miniaturized filters involves flip-chip soldering the filter die to a substrate using metal balls. The die is then covered with a plastic encapsulant to seal the die within the encapsulant. Finally, the encapsulant is cured and cut into individual finished filters. Due to the high fluidity of the encapsulant, commercially available encapsulants can easily intrude into the device during the encapsulation process, contaminating the filter's functional areas and cavity environment, affecting proper device operation and ultimately reducing the filter's production yield.

[0005] Therefore, how to provide a chip-level filter packaging film to prevent the functional area of ​​the filter chip from being contaminated by controlling the fluidity of the chip-level filter packaging film, thereby improving the production efficiency of the filter chip, is a technical problem that technical personnel in this field urgently need to solve.

[0006] Summary of the Invention

[0007] The object of the present invention is to provide a chip-level filter packaging film, a filter chip and a preparation method thereof, so as to solve at least one of the above-mentioned technical problems.

[0008] To achieve the above-mentioned purpose, the first aspect of the present invention provides a chip-level filter packaging film, which includes the following components in mass percentage: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000.

[0009] In the first aspect, the silica has a particle size D50 of 7 to 10 μm.

[0010] In the first aspect, the epoxy equivalent weight of the polyurethane-modified bisphenol A epoxy resin is 230 to 260 g / eq; and the epoxy equivalent weight of the tetrafunctional epoxy resin is 95 to 125 g / eq.

[0011] In the first aspect, the epoxy resin includes at least one of tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyldiaminodiphenylmethane, and tetraglycidylxylenediamine.

[0012] In the first aspect, the curing agent is a latent curing agent; the latent curing agent includes dicyandiamide.

[0013] In the first aspect, the accelerator is a latent accelerator; the latent accelerator includes an imidazole compound.

[0014] In the first aspect, the colorant includes carbon black; and the average particle size of the carbon black is 5 nm.

[0015] A second aspect of the present invention provides a method for preparing the chip-level filter packaging film according to the first aspect, the preparation method comprising:

[0016] S1. Stirring and mixing the components according to their respective mass percentages to obtain a first slurry, wherein the mass percentages of the components specifically include: the chip-level filter packaging film includes the following components by mass percentage: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000;

[0017] S2, transferring the first slurry to a bead mill for dispersion treatment to obtain a uniformly dispersed second slurry;

[0018] S3, vacuum degassing the second slurry to obtain a third slurry;

[0019] S4, coating the third slurry on the base film and drying it;

[0020] S5. After the drying is completed, the base film is removed to obtain a chip-level filter packaging film.

[0021] The third aspect of the present invention provides a method for preparing a filter chip, the preparation method comprising: stirring, mixing, bead milling and vacuum degassing the components in the chip-level filter packaging film described in the first aspect to obtain a mixed slurry; the mass percentages of the components specifically include: the chip-level filter packaging film comprises the following components by mass percentage: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin. The phenoxy resin has a molecular weight of 50,000 to 150,000; the mixed slurry is coated on a base film and dried to obtain a chip-level filter packaging film on the base film; a filter bare chip is obtained, and the lower surface of the filter bare chip is flip-chip soldered on a substrate through metal balls; the chip-level filter packaging film is covered on the upper surface of the filter bare chip by vacuum hot pressing; the conditions of the vacuum hot pressing include: a pressure of 0.1 to 0.5 MPa, a temperature of 50 to 70°C, and a time of 10 to 60 seconds; the mixture is cured at 150°C for 2 hours, and after curing, the mixture is cut to obtain a well-packaged filter chip.

[0022] A fourth aspect of the present invention provides a filter chip, which is manufactured using the filter chip manufacturing method described in the third aspect. Beneficial effects:

[0023] The present invention provides a chip-level filter packaging film, which comprises the following components by mass percentage: 55-70% silicon dioxide, 14-24% epoxy resin, 15-20% phenoxy resin, 1-2.5% curing agent, 0.5-1.2% accelerator, and 0.3-0.9% colorant. The epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin, and the molecular weight of the phenoxy resin is 50,000-150,000. The polarity of the polyurethane-modified bisphenol A epoxy resin is enhanced, thereby having a stronger effect on silicon dioxide. force, effectively increasing the surface properties of silica and improving the compatibility between polyurethane-modified bisphenol A epoxy resin and silica; tetrafunctional epoxy resin has high reactivity and can provide cross-linking fulcrums; phenoxy resin improves the wettability of silica, and phenoxy resin, polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin are used as matrix resins. By adjusting the ratio between the three and controlling the particle size of silica, the fluidity of the chip-level filter packaging film can be controlled, and under the catalysis of the curing agent and the accelerator, the curing efficiency is improved, thereby improving the packaging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] FIG1 is a flow chart of a method for preparing a chip-level filter packaging film of the present application

[0026] FIG2 is a schematic structural diagram of a filter chip of the present application;

[0027] FIG3 is a schematic structural diagram of a filter bare chip;

[0028] FIG4 is a diagram showing the packaging effect in Example 1 of the present application;

[0029] FIG5 is a diagram showing the packaging effect in Example 2 of the present application;

[0030] FIG6 is a diagram showing the packaging effect in Example 3 of the present application;

[0031] FIG7 is a diagram showing the packaging effect in Comparative Example 1 of the present application;

[0032] FIG8 is a diagram showing the packaging effect in Comparative Example 2 of the present application;

[0033] Reference numerals:

[0034] 1. Metal ball; 2. Substrate; 3. Cavity; 4. Filter bare chip; 4.1. Filter chip functional area; 4.2. Filter non-functional area; 5. Chip-level filter packaging film. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are for illustrating the present invention, rather than for limiting the present invention.

[0036] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as 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 belongs. In the event of any conflict, the present specification shall take precedence.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained through existing methods.

[0038] The present application provides a chip-level filter packaging film, which includes the following components in mass percentage: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000.

[0039] Specifically, the present invention provides a chip-level filter packaging film, which includes the following components by mass percentage: 55-70% silicon dioxide, 14-24% epoxy resin, 15-20% phenoxy resin, 1-2.5% curing agent, 0.5-1.2% accelerator, and 0.3-0.9% colorant. The epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin, and the molecular weight of the phenoxy resin is 50,000-150,000; the polarity of the polyurethane-modified bisphenol A epoxy resin is enhanced, thereby having a stronger effect on silicon dioxide. The effect of the force effectively increases the surface properties of silica and improves the compatibility between polyurethane-modified bisphenol A epoxy resin and silica; the tetrafunctional epoxy resin has high reactivity and can provide a cross-linking fulcrum; the phenoxy resin improves the wettability of silica. Phenoxy resin, polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin are used as matrix resins. By adjusting the ratio between the three and controlling the particle size of silica, the fluidity of the chip-level filter packaging film can be controlled, and under the catalysis of the curing agent and the accelerator, the curing efficiency can be improved, thereby improving the packaging efficiency.

[0040] In some possible embodiments, the particle size D50 of the silicon dioxide is 7 to 10 μm.

[0041] This is because, on the one hand, the selection of silica with a larger particle size as the filler can play a certain blocking role. The larger particle size powder can prevent the viscosity of the plastic packaging material from decreasing under temperature and pressure conditions, increasing fluidity and flowing into the cavity; on the other hand, it can adjust the appropriate storage modulus and thermal expansion coefficient. As a preferred embodiment, the particle size of silica D50 = 8.5um.

[0042] In some possible embodiments, the epoxy equivalent of the polyurethane-modified bisphenol A epoxy resin is 230 to 260 g / eq; and the epoxy equivalent of the tetrafunctional epoxy resin is 95 to 125 g / eq.

[0043] In some possible embodiments, the epoxy resin includes at least one of tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyldiaminodiphenylmethane, and tetraglycidylxylenediamine.

[0044] Those skilled in the art will appreciate that this application utilizes phenoxy resin, polyurethane-modified bisphenol A epoxy resin, and tetrafunctional epoxy resin as matrix materials, and controls the fluidity of the chip-level filter packaging membrane by adjusting the ratio of the three. Phenoxy resin improves the wettability of the filler, provides toughness, and enhances the adhesion of the material, while also controlling the appearance and rheological properties. Tetrafunctional epoxy resin, with its four epoxy groups, exhibits high reactivity, can increase the crosslinking density after curing, and exhibits excellent curing properties, high temperature resistance, and excellent weather resistance and aging resistance.

[0045] In some possible embodiments, the curing agent is a latent curing agent; the latent curing agent includes dicyandiamide.

[0046] After the latent curing agent is mixed with the epoxy resin, it can be stored stably at room temperature. Through heating reaction, it begins to dissolve and cures extremely quickly when it reaches near the melting point. The curing reaction temperature of dicyandiamide is 160-180℃, and it usually needs to be used with an accelerator.

[0047] In some possible embodiments, the accelerator is a latent accelerator; the latent accelerator includes an imidazole compound.

[0048] Latent accelerators can accelerate the reaction rate of epoxy resin and latent curing agent, reduce curing time and improve production efficiency; imidazole compounds can reduce the curing reaction temperature of dicyandiamide, such as 2-phenyl-4,5-dihydroxymethylimidazole.

[0049] In some possible embodiments, the colorant includes carbon black; and the average particle size of the carbon black is 5 nm.

[0050] Those skilled in the art will understand that the colorant is used to color the chip-level filter packaging film. In the present application, the colorant may be carbon black, and the average particle size of the carbon black is 5 nm.

[0051] Based on a general inventive concept, referring to FIG1 , the present application further provides a method for preparing the chip-level filter packaging film as described in the first aspect, the method comprising:

[0052] S1. Stirring and mixing the components according to their respective mass percentages to obtain a first slurry, wherein the mass percentages of the components specifically include: the chip-level filter packaging film includes the following components by mass percentage: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000;

[0053] S2, transferring the first slurry to a bead mill for dispersion treatment to obtain a uniformly dispersed second slurry;

[0054] S3, vacuum degassing the second slurry to obtain a third slurry;

[0055] S4, coating the third slurry on the base film and drying it;

[0056] S5. After the drying is completed, the base film is removed to obtain a chip-level filter packaging film.

[0057] The preparation method of the chip-level filter packaging film provided in the present application is simple and easy to operate.

[0058] Based on a general inventive concept, a method for preparing a filter chip includes:

[0059] S21. Stir, mix, bead-mill, and vacuum-degas the components of the chip-level filter packaging film described in the first aspect to obtain a mixed slurry; the mass percentages of the components specifically include: the chip-level filter packaging film comprises the following components by mass percentage: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000;

[0060] S22, coating the mixed slurry on a base film and drying the mixed slurry to obtain a chip-level filter packaging film on the base film;

[0061] S23, obtaining a filter bare chip, wherein the lower surface of the filter bare chip is flip-chip soldered on the substrate via metal balls;

[0062] S24, covering the chip-level filter packaging film on the upper surface of the filter bare chip by vacuum hot pressing; the conditions of the vacuum hot pressing include: pressure of 0.1-0.5 MPa, temperature of 50-70° C., and time of 10-60 seconds;

[0063] S25. Curing at 150° C. for 2 hours. After curing, cutting is performed to obtain a well-packaged filter chip.

[0064] Those skilled in the art can understand that under the conditions of vacuum hot pressing, the chip-level filter packaging film prepared according to the above-mentioned formula ratio has a certain fluidity, so that the packaging film flows toward the substrate and is in close contact with the upper surface of the filter bare chip, thereby completing the packaging of the filter bare chip. After the packaging is completed, it is cured to form a whole with the chip-level filter packaging film, the filter bare chip and the substrate. Then, by cutting, the filter chip of the expected size and good packaging is obtained, thereby meeting the packaging requirements of the miniaturized filter chip.

[0065] Based on a general inventive concept, the present application also provides a filter chip, which is manufactured using the filter chip preparation method described in the third aspect.

[0066] The structural schematic diagram of a filter chip provided in the present application is shown in Figure 2-3, including a metal ball 1, a substrate 2, a cavity 3, a filter bare chip 4 and a chip-level filter packaging film 5. The lower surface of the filter bare chip 4 is welded to the substrate 2 through several metal balls 1, and the chip-level filter packaging film 5 covers the filter bare chip 4 and contacts the substrate 2, thereby protecting the functional area of ​​the filter chip from contamination.

[0067] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0068] Example 1

[0069] The chip-level filter packaging film of this embodiment includes the following components in percentage by mass:

[0070] Among them, the molecular weight of phenoxy resin is 100,000.

[0071] In this embodiment, the chip-level filter package film is prepared by the following steps:

[0072] (1) Weighing the raw material components according to the above formula and stirring them evenly to obtain a first slurry;

[0073] (2) transferring the first slurry to a bead mill for dispersion treatment to obtain a uniformly dispersed second slurry;

[0074] (3) vacuum degassing the second slurry to obtain a third slurry;

[0075] (4) coating the third slurry on the base film and drying it;

[0076] (5) After drying, the base film is removed to obtain a chip-level filter packaging film.

[0077] The chip-level filter packaging film of this embodiment is applied to packaging filter chips, and the specific packaging process is as follows:

[0078] (21) Weighing the raw material components according to the above formula ratio, stirring and mixing, bead milling and vacuum degassing to obtain a mixed slurry;

[0079] (22) coating the mixed slurry on a base film and drying the mixed slurry to obtain a chip-level filter packaging film on the base film;

[0080] (23) obtaining a filter bare chip, wherein the lower surface of the filter bare chip is flip-chip soldered on the substrate via metal balls;

[0081] (24) Covering the chip-level filter packaging film on the upper surface of the filter bare chip by vacuum hot pressing to complete the packaging; the vacuum hot pressing conditions include: pressure of 0.3 MPa, temperature of 50° C., and time of 50 s;

[0082] (25) Curing at 150°C for 2 hours, and then cutting to obtain a well-packaged filter chip.

[0083] Example 2

[0084] The chip-level filter packaging film of this embodiment includes the following components in percentage by mass:

[0085] Among them, the molecular weight of phenoxy resin is 100,000.

[0086] The method for preparing the chip-level filter packaging film in this embodiment is the same as the method for preparing the chip-level filter packaging film in Example 1.

[0087] The chip-level filter packaging film of this embodiment is applied to packaging filter chips, and the specific packaging process is as follows:

[0088] (21) Weighing the raw material components according to the above formula ratio, stirring and mixing, bead milling and vacuum degassing to obtain a mixed slurry;

[0089] (22) coating the mixed slurry on a base film and drying the mixed slurry to obtain a chip-level filter packaging film on the base film;

[0090] (23) obtaining a filter bare chip, wherein the lower surface of the filter bare chip is flip-chip soldered on the substrate via metal balls;

[0091] (24) Covering the chip-level filter packaging film on the upper surface of the filter bare chip by vacuum hot pressing to complete the packaging; the vacuum hot pressing conditions include: pressure of 0.2 MPa, temperature of 60° C., and time of 30 seconds;

[0092] (25) Curing at 150°C for 2 hours, and then cutting to obtain a well-packaged filter chip.

[0093] Example 3

[0094] The chip-level filter packaging film of this embodiment includes the following components in percentage by mass:

[0095] Among them, the molecular weight of phenoxy resin is 100,000.

[0096] The method for preparing the chip-level filter packaging film in this embodiment is the same as the method for preparing the chip-level filter packaging film in Example 1.

[0097] The chip-level filter packaging film of this embodiment is applied to packaging filter chips, and the specific packaging process is as follows:

[0098] (21) Weighing the raw material components according to the above formula ratio, stirring and mixing, bead milling and vacuum degassing to obtain a mixed slurry;

[0099] (22) coating the mixed slurry on a base film and drying the mixed slurry to obtain a chip-level filter packaging film on the base film;

[0100] (23) obtaining a filter bare chip, wherein the lower surface of the filter bare chip is flip-chip soldered on the substrate via metal balls;

[0101] (24) Covering the chip-level filter packaging film on the upper surface of the filter bare chip by vacuum hot pressing to complete the packaging; the vacuum hot pressing conditions include: pressure of 0.1 MPa, temperature of 70° C., and time of 20 seconds;

[0102] (25) Curing at 150°C for 2 hours, and then cutting to obtain a well-packaged filter chip.

[0103] Comparative Example 1

[0104] The chip-level filter packaging film of this comparative example comprises the following components in percentage by mass:

[0105] The epoxy equivalent of the bisphenol F epoxy resin is 160-180 g / eq, and the molecular weight of the phenoxy resin is 100,000.

[0106] The preparation method of the chip-level filter packaging film in this comparative example is the same as the preparation method of the chip-level filter packaging film in Example 1.

[0107] The chip-level filter packaging film of this comparative example is applied to packaging filter chips, and the specific packaging process is as follows:

[0108] (21) Weighing the raw material components according to the above formula ratio, stirring and mixing, bead milling and vacuum degassing to obtain a mixed slurry;

[0109] (22) coating the mixed slurry on a base film and drying the mixed slurry to obtain a chip-level filter packaging film on the base film;

[0110] (23) obtaining a filter bare chip, wherein the lower surface of the filter bare chip is flip-chip soldered on the substrate via metal balls;

[0111] (24) Covering the chip-level filter packaging film on the upper surface of the filter bare chip by vacuum hot pressing to complete the packaging; the vacuum hot pressing conditions include: pressure of 0.2 MPa, temperature of 60° C., and time of 30 seconds;

[0112] (25) Curing at 150°C for 2 hours, and then cutting to obtain a well-packaged filter chip.

[0113] Comparative Example 2

[0114] The chip-level filter packaging film of this comparative example comprises the following components in percentage by mass:

[0115] Among them, the epoxy equivalent of bisphenol F epoxy resin is 160-180g / eq, and the molecular weight of acrylic resin is 300,000.

[0116] The preparation method of the chip-level filter packaging film in this comparative example is the same as the preparation method of the chip-level filter packaging film in Example 1.

[0117] The chip-level filter packaging film of this comparative example is applied to packaging filter chips, and the specific packaging process is as follows:

[0118] (21) Weighing the raw material components according to the above formula ratio, stirring and mixing, bead milling and vacuum degassing to obtain a mixed slurry;

[0119] (22) coating the mixed slurry on a base film and drying the mixed slurry to obtain a chip-level filter packaging film on the base film;

[0120] (23) obtaining a filter bare chip, wherein the lower surface of the filter bare chip is flip-chip soldered on the substrate via metal balls;

[0121] (24) Covering the chip-level filter packaging film on the upper surface of the filter bare chip by vacuum hot pressing to complete the packaging; the vacuum hot pressing conditions include: pressure of 0.4 MPa, temperature of 70° C., and time of 60 s;

[0122] (25) Curing at 150°C for 2 hours, and then cutting to obtain a well-packaged filter chip.

[0123] The chip-level filter packaging films provided in Examples 1-3 and Comparative Examples 1-2 were subjected to rheological tests, glue penetration distance, copper sheet adhesion, thixotropic coefficient, glass transition temperature, thermal expansion coefficient, and storage modulus. The specific testing process is as follows:

[0124] 1. Rheological Test: After coating the formulation into a film, cut it into 5cm x 5cm samples. Remove the release film and heat transfer the film to a thickness of 1000-1200μm at 100°C. Test the viscosity using a rheometer with a holding force of 2N at 50°C, 60°C, and 70°C.

[0125] 2. Glue penetration distance: After the formula is coated into a film, cut it into 9cm×9cm samples, tear off the light release film, cover the wave filter bare chip that has been flip-chip soldered to the substrate, and cut it into individual finished products after vacuum hot pressing and curing at 150℃ for 2h. Then pry open the substrate and measure its glue penetration distance d with an optical microscope; the glue that does not penetrate into the functional area of ​​the filter chip is marked as "+", the glue that penetrates the functional area of ​​the filter chip is marked as "×", and the glue that does not cover the chip all around (that is, the glue does not contact the substrate) is marked as "-".

[0126] 3. Adhesion to copper sheet: After coating the formula into a film, cut the film into 2mm×2mm pieces and transfer them to the copper sheet. After curing at 150℃ for 2h, use a universal tensile testing machine to test the shear bonding strength.

[0127] 4. Thixotropic coefficient (TI) test: The slurry obtained from the above formula was tested using an American Brookfield DV1MRV viscometer with a No. 21 rotor at a test temperature of 30°C. The viscosity value η1 at 0.5 rpm and the viscosity value η2 at 5 rpm were tested. TI = η1 / η2.

[0128] 5. Thermal expansion coefficient and glass transition temperature: The cured samples were measured according to ASTM E831-2019. The measurement parameters were as follows: preload force: 0.05 N, first scan: room temperature-250 ° C (heating rate 10 ° C / min) and second scan: room temperature-250 ° C (heating rate 10 ° C / min). The curve data of the second heating section was taken.

[0129] 6. Storage modulus test: The size of the test sample is 55 mm × 10 mm × 2 mm, and the storage modulus is tested using the ASTM E2254-2018 standard method.

[0130] The test results are shown in Table 1 below:

[0131] Table 1 Test results

[0132] The above table shows that the use of silica with a larger average particle size and the addition of a tetrafunctional epoxy resin can make the resulting film have lower fluidity and a higher thixotropic coefficient, and when applied to the filter bare chip, the glue penetration distance d does not contaminate the filter functional area; in addition, the use of a phenoxy resin with a molecular weight of 100,000 has better fluidity than the use of an acrylic resin with a molecular weight of 300,000, and can cover the filter chip and adhere to the substrate to form a cavity; finally, the addition of polyurethane-modified bisphenol A epoxy resin and phenoxy resin is beneficial to improving the adhesion of the film material to the substrate, which will facilitate subsequent cutting into individual filter packaging products.

[0133] It can be seen from the packaging effect diagrams of Figures 4-8 that the chip-level filter packaging film prepared in Examples 1-3 is used to package the filter bare chip. Although glue seepage occurs, the glue does not penetrate into the functional area of ​​the filter chip and does not affect the normal operation of the filter; in Comparative Example 1, the glue seepage is serious and the glue has penetrated into the functional area of ​​the filter chip, affecting the normal operation of the filter; in Comparative Example 2, the glue does not contact the substrate, that is, the packaging of the filter bare chip is not completed.

[0134] In summary, the chip-level filter packaging film provided by this application has low fluidity and can wrap around the filter chip, forming a closed cavity between the chip and the substrate, and the filter functional area is not contaminated, and has a high glass transition temperature and storage modulus. During use, it can wrap the filter chip without leaking glue into the cavity and contaminating the filter functional area; it simplifies the packaging method of the filter, improves the packaging efficiency and packaging yield, and reduces the packaging cost; at the same time, the film is directly applied to the plastic sealing of the filter, which can reduce the packaging size of the filter. The thickness of the corresponding film can be produced according to the total height of the flip-chip filter chip structure to reduce the size after packaging accordingly, which can better meet the future demand for miniaturized packaging.

[0135] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes 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.

[0136] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0137] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A chip-level filter packaging film, characterized in that: The chip-level filter packaging film comprises the following components by mass percentage: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000; The particle size D50 of the silicon dioxide is 7 to 10 μm; The epoxy equivalent weight of the polyurethane modified bisphenol A epoxy resin is 230 to 260 g / eq; the epoxy equivalent weight of the tetrafunctional epoxy resin is 95 to 125 g / eq; The tetrafunctional epoxy resin includes at least one of tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyldiaminodiphenylmethane and tetraglycidylxylenediamine; The sum of the mass percentages of the components is 100%.

2. The chip-level filter packaging film according to claim 1, characterized in that: The curing agent is a latent curing agent; the latent curing agent includes dicyandiamide.

3. The chip-level filter packaging film according to claim 2, characterized in that: The accelerator is a latent accelerator; the latent accelerator includes an imidazole compound.

4. The chip-level filter packaging film according to claim 3, characterized in that: The colorant includes carbon black; the average particle size of the carbon black is 5 nm.

5. A method for preparing a chip-level filter packaging film according to any one of claims 1 to 4, characterized in that: The preparation method comprises: S1. Stirring and mixing the components according to their respective mass percentages to obtain a first slurry, wherein the mass percentages of the components specifically include: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000; wherein the sum of the mass percentages of the components is 100%; S2, transferring the first slurry to a bead mill for dispersion treatment to obtain a uniformly dispersed second slurry; S3, vacuum degassing the second slurry to obtain a third slurry; S4, coating the third slurry on the base film and drying it; S5. After the drying is completed, the base film is removed to obtain a chip-level filter packaging film.

6. A method for preparing a filter chip, characterized in that: The preparation method comprises: The components of the chip-level filter packaging film according to any one of claims 1 to 4 are stirred, mixed, bead-milled, and vacuum-degassed to obtain a mixed slurry; the mass percentages of the components specifically include: 55% to 70% silicon dioxide, 14% to 24% epoxy resin, 15% to 20% phenoxy resin, 1% to 2.5% curing agent, 0.5% to 1.2% accelerator, and 0.3% to 0.9% colorant; the epoxy resin is composed of polyurethane-modified bisphenol A epoxy resin and tetrafunctional epoxy resin; the molecular weight of the phenoxy resin is 50,000 to 150,000; wherein the sum of the mass percentages of the components is 100%; Applying the mixed slurry on a base film and drying the mixed slurry to obtain a chip-level filter packaging film on the base film; Obtaining a filter bare chip, wherein the lower surface of the filter bare chip is flip-chip soldered on a substrate via metal balls; The chip-level filter packaging film is covered on the upper surface of the filter bare chip by vacuum hot pressing; the vacuum hot pressing conditions include: pressure of 0.1-0.5 MPa, temperature of 50-70° C., and time of 10-60 seconds; The filter chip was cured at 150°C for 2 hours and then cut to obtain a well-packaged filter chip.

7. A filter chip, characterized in that: The filter chip is manufactured using the filter chip manufacturing method according to claim 6.

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