Die attach film and preparation method therefor, and fingerprint sensor packaging structure

Abstract

Provided in the present invention are a die attach film and a preparation method therefor, and a fingerprint sensor packaging structure. The die attach film comprises the following components in parts by mass: 20-40 parts of spherical silicon dioxide, 20-35 parts of a phenoxy resin, 20-30 parts of a polyurethane-modified epoxy resin, 15-20 parts of a flexible epoxy resin, 1-4 parts of a curing agent, 0.1-0.5 parts of a promoter, 0.3-0.5 parts of a silane coupling agent, and 0.3-0.5 parts of a leveling agent. The die attach film prepared at a specific formulation ratio of the present invention has relatively high bonding strength, the thickness of a die film can be accurately controlled, the thickness of the film is kept consistent, and a die is prevented from tilting; therefore, the stability of die packaging is maintained, and the stability of a fingerprint sensor packaging structure is improved.

Description

Chip bonding film, preparation method thereof and fingerprint sensor packaging structure TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor packaging, and particularly relates to a chip bonding film, a preparation method thereof and a fingerprint sensor packaging structure. BACKGROUND

[0002] With the continuous development of electronic technology and semiconductor technology, the fingerprint sensor technology is also becoming more and more mature, and more and more electronic devices begin to use fingerprint sensors. In the specific practice process, the fingerprint sensor is made into a packaging structure and embedded in the electronic device. In the packaging structure, the chip is isolated and packaged from the substrate by the chip bonding film, and is electrically connected by the wire to realize fingerprint sensing. However, the chip bonding film is prone to breakage at high temperature, and the adhesion to the substrate is poor, so that the chip loses control, and the fingerprint sensing fails.

[0003] Therefore, how to provide a chip bonding film, by adjusting the proportion of three kinds of matrix resins of polyphenyl oxide resin, polyurethane modified epoxy resin and flexible epoxy resin, to improve the silicon wafer adhesion of the chip bonding film, and thus improve the stability of the fingerprint sensor packaging structure, is a technical problem that the person skilled in the art needs to solve. SUMMARY

[0004] The present application aims to provide a chip bonding film, a preparation method thereof and a fingerprint sensor packaging structure to at least solve the above technical problems.

[0005] To achieve the above-mentioned purpose, the present application provides a chip bonding film in the first aspect, which comprises the following components in mass fraction: 20-40 parts of spherical silica, 20-35 parts of polyphenyl oxide resin, 20-30 parts of polyurethane modified epoxy resin, 15-20 parts of flexible epoxy resin, 1-4 parts of curing agent, 0.1-0.5 parts of accelerator, 0.3-0.5 parts of silane coupling agent and 0.3-0.5 parts of leveling agent.

[0006] In the first aspect, the average particle size of the spherical silica is 10-15 μm.

[0007] In the first aspect, the epoxy equivalent weight of the flexible epoxy resin is 440-480 g / eq.

[0008] In the first aspect, the epoxy equivalent weight of the polyurethane modified epoxy resin is 210-280 g / eq.

[0009] In the first aspect, the molecular weight of the polyphenyl oxide resin is 32000-52000, and the epoxy equivalent weight of the polyphenyl oxide resin is 25 g / eq.

[0010] In the first aspect, the curing agent is a polyamine curing agent; the polyamine curing agent includes at least one of diethylenetriamine, m-phenylenediamine and dicyandiamide.

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

[0012] In the first aspect, the leveling agent includes KL-730.

[0013] The second aspect of the present application provides a preparation method of the chip bonding film as described in the first aspect, the preparation method comprising: weighing each component of raw materials respectively, the components including, in terms of mass fraction, 20-40 parts of spherical silica, 20-35 parts of polyphenol resin, 20-30 parts of polyurethane modified epoxy resin, 15-20 parts of flexible epoxy resin, 1-4 parts of curing agent, 0.1-0.5 parts of accelerator, 0.3-0.5 parts of silane coupling agent and 0.3-0.5 parts of leveling agent; adding propylene glycol methyl ether acetate to the weighed polyphenol resin, stirring uniformly to obtain a first mixed solution; sequentially adding the weighed polyurethane modified epoxy resin and the flexible epoxy resin to the first mixed solution, stirring uniformly to obtain a second mixed solution; adding the weighed spherical silica, the curing agent and the accelerator to the second mixed solution, stirring uniformly to obtain a third mixed solution; transferring the third mixed solution to a bead mill for grinding to obtain a glue-like substance; adding the weighed silane coupling agent and the leveling agent to the glue-like substance, vacuum defoaming to obtain a glue solution; coating the glue solution by a coating machine, drying to obtain the chip bonding film.

[0014] The third aspect of the present application provides a fingerprint sensor packaging structure, the packaging structure comprising: a substrate, the front and back surfaces of the substrate are provided with lines; a control chip, a first chip bonding film is arranged between the control chip and the back surface of the substrate, and the control chip is electrically connected with the lines on the back surface of the substrate; a hard material, the hard material is a fingerprint sensing area; a first metal frame, one end of the first metal frame is fixedly connected with the front surface of the substrate, and the other end of the first metal frame is fixedly connected with one side of the hard material; a second metal frame, one end of the second metal frame is fixedly connected with the front surface of the substrate, and the other end of the second metal frame is fixedly connected with the other side of the hard material, and the substrate, the hard material, the first metal frame and the second metal frame jointly form a containing space; a sensing chip, a second chip bonding film is arranged between the sensing chip and the front surface of the substrate, the sensing chip is electrically connected with the lines on the front surface of the substrate, the sensing chip is arranged in the containing space, and the containing space is filled with epoxy plastic sealing material; the first chip bonding film and the second chip bonding film are the chip bonding film of the first aspect. Advantages:

[0015] The chip bonding film provided by the present application comprises the following components in mass fraction: 20-40 parts of spherical silica, 20-35 parts of polyphenol resin, 20-30 parts of polyurethane modified epoxy resin, 15-20 parts of flexible epoxy resin, 1-4 parts of curing agent, 0.1-0.5 parts of accelerator, 0.3-0.5 parts of silane coupling agent and 0.3-0.5 parts of leveling agent. The toughness and bonding strength of the three resins, i.e., the polyphenol resin, the polyurethane modified epoxy resin and the flexible epoxy resin, provide the basic performance of the chip bonding film, and the bonding strength of the chip bonding film is adjusted by adjusting the proportion of the three resins. The internal stress and the thermal expansion coefficient of the chip bonding film are reduced by the spherical silica. The resin is cured by the curing agent, and the curing time is reduced and the curing efficiency is improved by the accelerator. The leveling agent is used to increase the film forming property, so that the prepared chip bonding film has thickness consistency, and the attached chip can be prevented from tilting, and the stability of the chip packaging is maintained. The chip bonding film prepared by the specific formula proportion has high bonding strength, the thickness of the chip film can be accurately controlled, the film thickness consistency is maintained, the chip tilting is prevented, and the stability of the chip packaging is maintained, thereby improving the stability of the fingerprint sensor packaging structure. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0017] Fig. 1 is a flow chart of a chip bonding film preparation method provided by the present application.

[0018] Fig. 2 is a structural schematic diagram of a fingerprint sensor packaging structure provided by the present application.

[0019] Reference signs: 1, substrate; 2, control chip; 3, hard material; 4, first metal frame; 5, second metal frame; 6, sensing chip; 7, first chip bonding film; 8, second chip bonding film; 9, epoxy plastic sealing material; 10, fingerprint. DETAILED DESCRIPTION

[0020] The advantages and various effects of the present application will be more clearly presented by the following specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, not to limit the present application.

[0021] Throughout the specification, unless otherwise specifically indicated, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs. If there is a contradiction, the present specification is preferred.

[0022] Unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be obtained by existing methods.

[0023] The chip bonding film provided by the present application comprises the following components in mass fraction: spherical silica 20-40 parts, polyphenol oxide resin 20-35 parts, polyurethane modified epoxy resin 20-30 parts, flexible epoxy resin 15-20 parts, curing agent 1-4 parts, accelerator 0.1-0.5 parts, silane coupling agent 0.3-0.5 parts, and leveling agent 0.3-0.5 parts.

[0024] Specifically, the chip bonding film comprises the following components in mass fraction: spherical silica 20-40 parts, polyphenol resin 20-35 parts, polyurethane modified epoxy resin 20-30 parts, flexible epoxy resin 15-20 parts, curing agent 1-4 parts, accelerator 0.1-0.5 parts, silane coupling agent 0.3-0.5 parts, and leveling agent 0.3-0.5 parts. The toughness and bonding strength of the three resins, i.e., the polyphenol resin, the polyurethane modified epoxy resin and the flexible epoxy resin, provide the basic performance of the chip bonding film, and the bonding strength of the chip bonding film is adjusted by adjusting the proportion of the three resins. The internal stress and the thermal expansion coefficient of the chip bonding film are reduced by the spherical silica. The resin is cured by the curing agent, and the curing time is reduced and the curing efficiency is improved by the accelerator, and the film forming property is improved by the leveling agent, so that the prepared chip bonding film has thickness consistency, and the attached chip can be prevented from tilting, and the stability of the chip packaging is maintained. The chip bonding film prepared by the specific formula proportion has high bonding strength, the thickness of the chip film can be accurately controlled, the film thickness consistency is maintained, the chip tilting is prevented, and the stability of the chip packaging is maintained, and the stability of the fingerprint sensor packaging structure is improved.

[0025] In some possible embodiments, the average particle size of the spherical silica is 10-15 μm.

[0026] This is because the spherical silica is selected as the filling material, and the average particle size of the spherical silica is controlled to be 10-15 μm, so that the thermal expansion coefficient of the film can be reduced, the flowability of the film before curing can be controlled, and the surface performance of the film can be improved in combination with the leveling agent.

[0027] In some possible embodiments, the epoxy equivalent weight of the flexible epoxy resin is 440-480 g / eq.

[0028] In some possible embodiments, the epoxy equivalent weight of the polyurethane modified epoxy resin is 210-280 g / eq.

[0029] In some possible embodiments, the molecular weight of the polyphenol resin is 32000-52000, and the epoxy equivalent weight of the polyphenol resin is 25 g / eq.

[0030] The skilled in the art can understand that the flexible epoxy resin has excellent toughness and good bonding strength, and the optional model is YX7400 or YX7105; the polyurethane modified epoxy resin has good bonding strength, high peel strength and high toughness, and the optional model is EPU-133 or EPU-302; the polyphenol epoxy resin has good toughness and adhesion strength, and is soluble in various organic solvents, and the optional model is PKHB or PKHH; by adjusting the proportion of the three resins, the toughness and bonding strength of the film can be adjusted, and the silane coupling agent is combined to further improve the adhesion between the film and the chip, so that the chip can be stably attached to the film, and the stability of the chip packaging is improved.

[0031] In some possible embodiments, the curing agent is a polyamine curing agent; the polyamine curing agent includes at least one of diethylenetriamine, m-phenylenediamine and dicyandiamide.

[0032] In some possible embodiments, the accelerator is an imidazole accelerator; the imidazole accelerator includes at least one of 2-ethyl-4-methylimidazole and 2-methylimidazole.

[0033] This is because the selected three resins have excellent adaptability, a polyamine curing agent is used to react with the resin, and an imidazole accelerator is combined to improve the reaction rate; wherein the diethylenetriamine is an aliphatic amine, and the active hydrogen equivalent is 45 g / eq; the m-phenylenediamine is an aromatic amine, and the active hydrogen equivalent is 21 g / eq; and the active hydrogen equivalent of dicyandiamide is 21 g / eq.

[0034] In some possible embodiments, the model of the leveling agent includes KL-730.

[0035] The skilled in the art can understand that the leveling agent KL-730 is a modified polymer with a side chain containing silicone, which can improve the leveling and uniformity of the glue solution, facilitate curing into a film, and the film has excellent performance.

[0036] Based on one overall inventive concept, referring to FIG. 1, a second aspect of the present application provides a preparation method of a chip bonding film, the preparation method comprising:

[0037] S1, respectively weighing each component of the raw material, the components include, in parts by mass: 20-40 parts of spherical silica, 20-35 parts of polyphenol epoxy resin, 20-30 parts of polyurethane modified epoxy resin, 15-20 parts of flexible epoxy resin, 1-4 parts of curing agent, 0.1-0.5 parts of accelerator, 0.3-0.5 parts of silane coupling agent, and 0.3-0.5 parts of leveling agent;

[0038] S2, adding propylene glycol methyl ether acetate to the weighed polyphenol epoxy resin, stirring uniformly to obtain a first mixed solution;

[0039] S3, sequentially adding weighed polyurethane modified epoxy resin and flexible epoxy resin into the first mixed solution, stirring uniformly to obtain a second mixed solution;

[0040] S4, adding weighed spherical silica, curing agent and accelerator into the second mixed solution, stirring uniformly to obtain a third mixed solution;

[0041] S5, transferring the third mixed solution to a bead mill for grinding to obtain a colloidal substance;

[0042] S6, adding weighed silane coupling agent and leveling agent into the colloidal substance, vacuum defoaming to obtain a colloidal solution;

[0043] S7, coating the colloidal solution by a coating machine, drying to obtain a chip bonding film.

[0044] In the process of preparing the chip bonding film, in order to reduce the stress between each raw material component, the polyphenol oxide resin is first dissolved by propylene glycol methyl ether acetate, then the polyurethane modified epoxy resin and the flexible epoxy resin are added and mixed uniformly, then the spherical silica, the curing agent and the accelerator are added, the grinding is carried out by the bead mill, so that the solid additives can be uniformly dispersed in the liquid resin and fully contacted, the contact area between the raw materials is improved, which provides a basis for the subsequent rapid reaction, finally the silane coupling agent and the leveling agent are added, and vacuum defoaming is carried out to remove the bubbles in the colloidal solution, which is beneficial to coating and can control the thickness of the coated colloidal solution, after coating, drying is carried out to remove the solvent and initiate the curing reaction, so that the raw materials react with each other to obtain a chip bonding film with high bonding strength, which can fix the chip in the fingerprint sensor and maintain the stability of the chip.

[0045] Based on one total inventive concept, referring to Fig. 2, the third aspect of the present application provides a fingerprint sensor packaging structure, which comprises: a substrate 1, the front and back surfaces of which are provided with lines; a control chip 2, which is provided with a first chip bonding film 7 between the back surface of the substrate 1, and is electrically connected with the lines on the back surface of the substrate 1; a hard material 3, which is a fingerprint sensing area; a first metal frame 4, one end of which is fixedly connected with the front surface of the substrate 1, and the other end of which is fixedly connected with one side of the hard material 3; a second metal frame 5, one end of which is fixedly connected with the front surface of the substrate 1, and the other end of which is fixedly connected with the other side of the hard material 3, and the substrate 1, the hard material 3, the first metal frame 4 and the second metal frame 5 jointly form a containing space; a sensing chip 6, which is provided with a second chip bonding film 8 between the front surface of the substrate 1, and is electrically connected with the lines on the front surface of the substrate 1, and is placed in the containing space, and the containing space is filled with epoxy plastic sealing material 9; the first chip bonding film 7 and the second chip bonding film 8 are the chip bonding film of the first aspect.

[0046] The first chip bonding film 7 is arranged between the control chip 2 and the substrate 1, the second chip bonding film 8 is arranged between the sensing chip 2 and the substrate 1, the chips are fixed on the substrate 1 by the first chip bonding film 7 and the second chip bonding film 8, the epoxy plastic sealing material 9 is arranged on the sensing chip 2, the hard material 3, the first metal frame 4 and the second metal frame 5 are combined for packaging, and the fingerprint sensing area is formed on the hard material 3, when the fingerprint 10 contacts the hard material 3, the sensing chip 2 receives a signal, the signal is transmitted to the control chip 2 through the wire, the received signal is identified by the control chip 2, and the fingerprint identification is completed, so that the stability of the fingerprint sensor packaging structure is maintained, and the fingerprint sensing and identification are improved.

[0047] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. The experimental methods in the following examples are not specified, and the methods are generally determined according to the national standards. If there is no corresponding national standard, the methods are determined according to the general international standards, conventional conditions, or the conditions suggested by the manufacturers.

[0048] The components of the chip bonding film in the comparative examples 1-9 and the examples 1-8 are shown in the following Tables 1-2 according to the mass fraction:

[0049] Table 1 Mass fraction of raw material components in comparative examples

[0050] Table 2: Allocation ratio of each component of raw materials in examples

[0051] The chip bonding film provided in Examples 1-8 and Comparative Examples 1-9 was subjected to film tensile strength and elongation at break test, cured tensile strength and elongation at break test, water absorption test, and silicon wafer adhesion test, and the test procedures were as follows:

[0052] 1. Film tensile strength and elongation at break test: cut 10 mm x 80 mm film material, tear off the release film, stick the two ends of the sample with tape, clamp the two ends of the tape with the clamp of the universal material testing machine, then tear off the release film, and test the tensile strength and elongation at break of the film;

[0053] 2. Cured tensile strength and elongation at break test: cure the film at 175°C for 2h, make a sample with a size of 50mm x 10mm x 1mm, make a dumbbell type, and test the tensile strength and elongation at break with a universal material testing machine;

[0054] 3. Water absorption test: take 3 pieces of 35mm x 35mm film material, weigh after curing at 175°C for 2h, then use a high temperature and high pressure cooking instrument at a constant temperature of 120°C for 24h, wipe off the surface moisture after the end, weigh in turn to calculate the water absorption, and take the average value;

[0055] 4. Silicon wafer adhesion test: attach a 20μm thick chip bonding film to a 10mm x 10mm silicon wafer, then attach a 2mm x 2mm small silicon wafer to the film, cure at 175°C for 2h, then measure the shear strength with a multifunctional thrust machine, and set the knife height to 30μm.

[0056] The test results are shown in Table 3 below:

[0057] Table 3: Test results

[0058] From the above table, it can be seen that:

[0059] (1) Although polyphenol resin, polyurethane modified epoxy resin and flexible epoxy resin were used as matrix resin in Comparative Example 1-5, the addition range was outside the specific ratio of the present application, so the film tensile strength and film elongation of the chip bonding film prepared were low, and the cured tensile strength and elongation at break were also low, and the adhesion to the silicon wafer was also low, which was not enough to stably adhere the sensing chip / control chip to the substrate to avoid movement of the chip;

[0060] (2) Comparative Example 7 only uses polyphenolic oxygen resin as the base resin, and Comparative Example 9 only uses polyurethane modified epoxy resin as the base resin, and the performance of the prepared film is the worst, because the performance of a single resin is relatively single, and the improvement of the comprehensive performance of the film is small; Comparative Example 8 uses polyphenolic oxygen resin and polyurethane modified epoxy resin as the base resin, and the performance of the prepared film is still poor, which shows that the flexible epoxy resin in the application has a greater impact on the comprehensive performance of the film;

[0061] (3) Examples 1-8 use polyphenolic oxygen resin, polyurethane modified epoxy resin and flexible epoxy resin as the base resin, and the comprehensive performance of the chip bonding film prepared is significantly changed, the adhesion of the film to the silicon wafer is significantly increased, the stability of the sensing chip / control chip is improved, and the sensing and recognition of the fingerprint sensor is improved.

[0062] Finally, it should be noted that the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment.

[0063] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0064] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A die attach film, comprising: The chip bonding film comprises the following components in mass fraction: spherical silica 20-40 parts, polyphenol resin 20-35 parts, polyurethane modified epoxy resin 20-30 parts, flexible epoxy resin 15-20 parts, curing agent 1-4 parts, accelerator 0.1-0.5 parts, silane coupling agent 0.3-0.5 parts, and leveling agent 0.3-0.5 parts; The epoxy equivalent weight of the flexible epoxy resin is 440-480 g / eq; the flexible epoxy resin is YX7400 or YX7105; The epoxy equivalent weight of the polyurethane modified epoxy resin is 210-280 g / eq; the polyurethane modified epoxy resin is EPU-133 or EPU-302; The molecular weight of the polyphenol resin is 32000-52000, and the epoxy equivalent weight of the polyphenol resin is 25 g / eq; the polyphenol resin is PKHB or PKHH.

2. The die attach film of claim 1, wherein The average particle size of the spherical silica is 10-15 μm.

3. The die attach film of claim 1, wherein, The curing agent is a polyamine curing agent; the polyamine curing agent comprises at least one of diethylene triamine, m-phenylenediamine and dicyandiamide.

4. The die attach film of claim 1, wherein, The accelerator is an imidazole accelerator; the imidazole accelerator comprises at least one of 2-ethyl-4-methylimidazole and 2-methylimidazole.

5. The die attach film of claim 1, wherein, The type of the leveling agent comprises KL-730.

6. A method of producing a die bonding film according to any one of claims 1 to 5, characterized by, The preparation method comprises: The components are weighed respectively; the components comprise the following components in mass fraction: spherical silica 20-40 parts, polyphenol resin 20-35 parts, polyurethane modified epoxy resin 20-30 parts, flexible epoxy resin 15-20 parts, curing agent 1-4 parts, accelerator 0.1-0.5 parts, silane coupling agent 0.3-0.5 parts, and leveling agent 0.3-0.5 parts; Propylene glycol methyl ether acetate is added to the weighed polyphenol resin, and stirred uniformly to obtain a first mixture; The weighed polyurethane modified epoxy resin and the flexible epoxy resin are sequentially added to the first mixture, and stirred uniformly to obtain a second mixture; The weighed spherical silica, the curing agent and the accelerator are added to the second mixture, and stirred uniformly to obtain a third mixture; The third mixture is transferred to a bead mill for grinding to obtain a glue; The weighed silane coupling agent and the leveling agent are added to the glue, and vacuum defoaming is performed to obtain a glue solution; The glue solution is coated by a coating machine, and dried to obtain a chip bonding film.

7. A fingerprint sensor package structure, characterized by The packaging structure comprises: A substrate, the front surface and the back surface of the substrate are both provided with a circuit; A control chip, a first chip bonding film is arranged between the control chip and the back surface of the substrate, and the control chip is electrically connected with the circuit on the back surface of the substrate; A hard material, the hard material is a fingerprint sensing area; A first metal frame, one end of the first metal frame is fixedly connected with the front surface of the substrate, and the other end of the first metal frame is fixedly connected with one side of the hard material; A second metal frame, one end of the second metal frame is fixedly connected with the front surface of the substrate, the other end of the second metal frame is fixedly connected with the other side of the hard material, and the substrate, the hard material, the first metal frame and the second metal frame jointly form a containing space; An inductive chip, the inductive chip is provided with a second chip bonding film between the inductive chip and the front surface of the substrate, the inductive chip is electrically connected with the circuit on the front surface of the substrate, the inductive chip is placed in the containing space, and the containing space is filled with epoxy plastic sealing material; The first chip bonding film and the second chip bonding film are the chip bonding film according to any one of claims 1-5.

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