Epoxy functional film for regulating and controlling warpage of wafer, and preparation method therefor and use thereof

Abstract

Provided in the present invention is an epoxy functional film for regulating and controlling the warpage of a wafer, which epoxy functional film comprises the following raw materials in percentage by mass: 33% of an epoxy resin, 50%-52% of silicon dioxide, 12%-14% of a curing agent, 1% of a curing accelerator, and 2% of a coloring agent, wherein the epoxy resin comprises a bisphenol F type epoxy resin and an o-cresol formaldehyde epoxy resin. The warping degree of the epoxy functional film is changed by adjusting the ratio of the bisphenol F type epoxy resin to the o-cresol formaldehyde epoxy resin; moreover, the above raw materials are stirred and mixed to obtain a slurry, the slurry is coated onto the back surface of a wafer body, and after curing, the epoxy functional film formed by a novolac epoxy resin has relatively high contractility and a relatively large warping degree to drive the back surface of the wafer body to warp, thereby further driving the front surface of the wafer body to warp reversely.

Description

Wafer warpage control epoxy functional film, preparation method and application thereof Technical Field

[0001] The present invention belongs to the technical field of electronic device packaging, and in particular relates to a wafer warpage regulating epoxy functional film and a preparation method and application thereof. Background Art

[0002] Wafer-level chip-scale packaging (WLCSP) is a process that performs packaging integration on a substrate, significantly reducing the footprint of the package structure. While traditional packaging is completed after the wafer is sliced ​​into individual chips, WLCSP utilizes a process that packages and tests the chips on the wafer itself. Compared to traditional packaging processes, wafer-level packaging offers significant cost savings.

[0003] However, during the wafer-level chip-scale packaging process, warping occurs due to the different thermal expansion coefficients of various materials in the component. When the warping exceeds a certain extent, it will cause poor soldering quality in the electronic circuit surface mount technology (SMT), thereby affecting the subsequent redistribution layer (RDL) process.

[0004] Therefore, how to provide a wafer warpage regulating epoxy functional film to control the warpage of the wafer is a technical problem that needs to be solved urgently by those skilled in the art.

[0005] Summary of the Invention

[0006] The object of the present invention is to provide a wafer warpage regulating epoxy functional film and its preparation method and application, so as to solve at least one of the above-mentioned technical problems.

[0007] To achieve the above-mentioned objectives, the first aspect of the present invention provides a wafer warpage regulating epoxy functional film. The raw material components of the epoxy functional film include, by mass percentage: 33% epoxy resin, 50%-52% silica, 12%-14% curing agent, 1% curing accelerator and 2% colorant; wherein, the epoxy resin includes bisphenol F epoxy resin and o-cresol epoxy resin.

[0008] In the first aspect, the epoxy equivalent weight of the bisphenol F epoxy resin is 160-180 g / eq; the epoxy equivalent weight of the o-cresol novolac epoxy resin is 180-190 g / eq.

[0009] In the first aspect, the curing agent includes a naphthol curing agent.

[0010] In the first aspect, the naphthol curing agent has a hydroxyl equivalent of 100-120 g / eq.

[0011] In the first aspect, the silica comprises fused silica; and the particle size D50 of the fused silica is 0.3 μm.

[0012] In the first aspect, the curing accelerator includes triphenylphosphine.

[0013] In the first aspect, the colorant includes carbon black, and the average particle size of the carbon black is 31 nm.

[0014] The second aspect of the present invention provides a method for preparing a wafer warpage regulating epoxy functional film, the preparation method comprising: stirring and mixing the raw material components in any one of the above-mentioned wafer warpage regulating epoxy functional films to obtain a slurry; and coating the slurry to obtain a wafer warpage regulating epoxy functional film.

[0015] The third aspect of the present invention provides a method for regulating the warpage of a wafer, the method comprising: in the process of preparing the wafer, a layer of a wafer warpage regulating epoxy functional film as described in any one of the above items is attached to the back of the wafer body; after the wafer warpage regulating epoxy functional film is cured, the wafer warpage regulating epoxy functional film drives the back side of the wafer body to warp, and then drives the front side of the wafer body to reverse warp; the curing conditions include: the curing temperature is 220°C; the curing time is 4 hours.

[0016] The fourth aspect of the present invention provides a method for preparing a wafer, which includes: obtaining a wafer body; attaching a layer of wafer warpage regulating epoxy functional film as described in any one of the above items on the back of the wafer body, and entering the redistribution layer process; after the redistribution layer process is completed, grinding off the wafer warpage regulating epoxy functional film to obtain a wafer. Beneficial effects:

[0017] The present invention provides a wafer warpage regulating epoxy functional film. The raw material components of the epoxy functional film include, by mass percentage, 33% epoxy resin, 50%-52% silicon dioxide, 12%-14% curing agent, 1% curing accelerator and 2% colorant. The epoxy resin includes bisphenol F epoxy resin and o-cresol epoxy resin. The thermal shrinkage of the phenolic epoxy resin is relatively large. Films formed by adding different proportions of the phenolic epoxy resin have different thermal expansion coefficients. During the high-temperature curing process, the formed film has a higher thermal expansion coefficient and also has higher shrinkage after curing, and the resulting warpage is also larger. The present invention adjusts the ratio of the bisphenol F epoxy resin and the o-cresol epoxy resin to thereby change the warpage of the epoxy functional film. At the same time, the above raw material components are stirred and mixed to obtain a slurry, which is coated on the back side of the wafer. After curing, the epoxy functional film formed by the phenolic epoxy resin has higher shrinkage and larger warpage, thereby causing the back side of the wafer to warp, thereby causing the front side of the wafer to reversely warp. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] FIG1 is a flow chart of a wafer preparation method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The present application provides a wafer warpage regulating epoxy functional film, in which the raw material components of the epoxy functional film include, by mass percentage, 33% epoxy resin, 50%-52% silicon dioxide, 12%-14% curing agent, 1% curing accelerator and 2% colorant; wherein the epoxy resin includes bisphenol F epoxy resin and o-cresol epoxy resin.

[0024] In some possible embodiments, the epoxy equivalent weight of the bisphenol F epoxy resin is 160-180 g / eq; and the epoxy equivalent weight of the o-cresol novolac epoxy resin is 180-190 g / eq.

[0025] Novolac epoxy resin has a relatively large thermal shrinkage. Adding different proportions of novolac epoxy resin to form films has different thermal expansion coefficients. During the high-temperature curing process, the formed film has a higher thermal expansion coefficient and also has higher shrinkage after curing, resulting in greater warpage. The present invention adjusts the ratio of bisphenol F epoxy resin and o-cresol epoxy resin to thereby change the warpage of the epoxy functional film. Bisphenol F epoxy resin and o-cresol epoxy resin can be purchased from the market. For example, bisphenol F epoxy resin is NPEF-170 from Jiadida New Materials Co., Ltd., and o-cresol epoxy resin is SQCN701-40 from Jinan Shengquan Group Co., Ltd.

[0026] In some possible embodiments, the curing agent includes a naphthol curing agent.

[0027] In some possible embodiments, the hydroxyl equivalent of the naphthol curing agent is 100-120 g / eq.

[0028] The hydroxyl groups in naphthol curing agents react with the epoxy groups in o-cresol-formaldehyde epoxy resin to form a segment of the cured product. This reaction then gradually crosslinks the linear molecules into three-dimensional molecules, enhancing the strength of the epoxy functional film. Naphthol curing agents are commercially available, such as SN-395 from Kenmet Materials Technology Co., Ltd.

[0029] In some possible embodiments, the silica comprises fused silica.

[0030] In some possible embodiments, the particle size of the fused silica is D50=0.3 μm.

[0031] Silica particles can be evenly dispersed in phenolic epoxy resin, creating a strong interfacial interaction with the resin matrix and enhancing interfacial bonding. When the matrix is ​​deformed by external forces, the silica particles are unlikely to separate from the matrix. This effectively transfers the tensile stress within the matrix and effectively prevents plastic deformation and crack propagation, thus enhancing toughness.

[0032] In some possible embodiments, the curing accelerator includes triphenylphosphine.

[0033] The curing accelerator includes triphenylphosphine, which can be used to initiate the addition reaction between the naphthol curing agent and the o-cresol-formaldehyde epoxy resin to accelerate the reaction rate.

[0034] In some possible embodiments, the colorant includes carbon black, and the average particle size of the carbon black is 31 nm.

[0035] The colorant includes carbon black, and the average particle size of the carbon black is 31 nm, which is used to dye the epoxy functional film.

[0036] Based on a general inventive concept, the present application also provides a method for preparing a wafer warpage regulating epoxy functional film, wherein the raw material components in the above-provided epoxy functional film are stirred and mixed to obtain a slurry; and the slurry is coated to obtain a wafer warpage regulating epoxy functional film.

[0037] Based on a general inventive concept, the present application also provides a method for regulating the warpage of a wafer, the method comprising: in the process of preparing the wafer, a layer of any of the above-mentioned wafer warpage regulating epoxy functional films is affixed to the back of the wafer body; after the wafer warpage regulating epoxy functional film is cured, the wafer warpage regulating epoxy functional film drives the back of the wafer body to warp, and then drives the front of the wafer body to reverse warp; the curing conditions include: the curing temperature is 220°C; the curing time is 4 hours.

[0038] Based on a general inventive concept, the present application also provides a method for preparing a wafer, which includes: obtaining a wafer body; attaching a layer of any of the above-mentioned wafer warpage regulating epoxy functional films on the back of the wafer body, and entering a redistribution layer process; after the redistribution layer process is completed, grinding off the wafer warpage regulating epoxy functional film to obtain a wafer.

[0039] 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.

[0040] The raw material components of a wafer warpage regulating epoxy functional film according to Examples 1-4 and Comparative Examples 1-2 are shown in Table 1 in terms of mass percentage:

[0041] Table 1 Raw material components by mass percentage

[0042] The raw material components in Examples 1-4 and Comparative Examples 1-2 were mixed and stirred to prepare a slurry, which was then coated into a thin film for testing. The specific testing process is as follows:

[0043] 1. Warpage test: After the formula is made into a slurry, it is coated into a 40μm thick film, cut into samples of size 20mm×20mm, and the light release film is torn off. The functional film is heat-transferred to a round glass sheet with a thickness of 100μm and a diameter of 10cm under 90℃ / 2kg pressure. The heavy release film is torn off and the functional film at the edge of the glass sheet is cleanly cut. The glass sheet is placed in an oven and cured at 220℃ / 4h. After curing, it is naturally cooled to room temperature. After being placed at room temperature for 24h, the warpage of the glass sheet is measured with a steel ruler.

[0044] 2. Tensile strength at break (film strength): After the formula is made into a slurry, it is coated into a 40μm thick film, which is then cut into samples of size 10mm x 55mm. The sample is tested at 24°C using a universal tensile testing machine at a test speed of 300mm / min, and the maximum tensile strength at break is recorded.

[0045] 3. 220℃ silicon wafer adhesion test: A 2mm×2mm 40μm thick film was transferred to the silicon wafer. After curing at 150℃ for 1h, the silicon wafer was heated to 220℃ using a universal tensile testing machine and the shear bond strength was tested.

[0046] 4. Substrate peeling force test: After the formula is made into a slurry, it is coated into a 40μm thick film, which is then cut into samples of size 150mm×25mm. At 24°C, the film is peeled off perpendicularly to the substrate at 90°. The test is performed using a universal tensile testing machine at a test speed of 300mm / min, and the maximum stable peeling force is recorded.

[0047] 5. Thermal Expansion Coefficient: Take 35-40 sheets of 40μm thick film, 100mm x 150mm in size, and heat-stack the sheets at 90°C / 2kg pressure. Then cut them into 10mm x 60mm samples and place them in a mold. Heat-cure them at 180°C for 1 hour. Remove the cured samples from the mold and cut 10mm x 10mm, 1.2mm thick sheets to form sample sheets for thermal expansion coefficient measurement. Place the samples on a TMA and perform thermal analysis at temperatures from room temperature to 250°C. After the measurement, read the thermal expansion coefficient values ​​in the range of 175-220°C.

[0048] The test results are shown in Table 2:

[0049] Table 2 Test results

[0050] It should be noted that the epoxy functional film provided by the present invention will be used in an automatic film laminating machine during application, and its normal operational requirements are: a. The tensile strength at break is in the range of 140-220 gf / 10 mm; b. The peeling force to the substrate is in the range of 20-35 gf / 25 mm; c. The adhesion to the silicon wafer at 220°C is required to be no less than 5 MPa.

[0051] As can be seen from the above table and Figure 1, the epoxy functional films prepared using Examples 2 and 3 of the present application are suitable for automatic laminating machines and have a relatively large warpage. A mold with a thickness of 600 μm and a warpage of +6 mm was selected, and a layer of epoxy functional film prepared in Example 3 or Example 4 was applied with a coating thickness of 40 μm and a warpage of +3 mm. After coating, the epoxy functional film was cured, and the mold was reversely warped with a warpage of -1 mm, and then entered the subsequent RDL process. After the RDL process was completed, the coated epoxy functional film was ground off, so that the warpage of the mold was controlled to about 0.5 mm for the next process.

[0052] 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.

[0053] 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.

[0054] 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 wafer warpage regulating epoxy functional film, characterized in that: In terms of mass percentage, the epoxy functional film is composed of 33% epoxy resin, 50%-52% silica, 12%-14% curing agent, 1% curing accelerator and 2% colorant; wherein the epoxy resin includes bisphenol F epoxy resin and o-cresol epoxy resin; the curing agent includes naphthol curing agent; the hydroxyl equivalent of the naphthol curing agent is 100-120g / eq; the curing accelerator includes triphenylphosphine; the epoxy equivalent of the bisphenol F epoxy resin is 160-180g / eq; the epoxy equivalent of the o-cresol epoxy resin is 180-190g / eq; the silica includes fused silica; the particle size D50 of the fused silica is 0.3μm; the colorant includes carbon black, and the average particle size of the carbon black is 31nm.

2. A method for preparing a wafer warpage-controlled epoxy functional film, characterized in that: The preparation method comprises: Stirring and mixing the raw material components of the wafer warpage regulating epoxy functional film according to claim 1 to obtain a slurry; The slurry is coated to obtain a wafer warpage regulating epoxy functional film.

3. A method for regulating wafer warpage, characterized in that: The method comprises: During the process of preparing the wafer, a layer of the wafer warpage regulating epoxy functional film as described in claim 1 is attached to the back of the wafer body. After the wafer warpage regulating epoxy functional film is cured, the wafer warpage regulating epoxy functional film drives the back of the wafer body to warp, and then drives the front of the wafer body to reversely warp. The curing conditions include: the curing temperature is 220°C; the curing time is 4 hours.

4. A method for preparing a wafer, characterized in that: The method comprises: Obtaining a wafer body; A wafer warpage regulating epoxy functional layer as claimed in claim 1 is attached to the back of the wafer body. Film, enter the redistribution layer process; After the redistribution layer process is completed, the wafer warpage regulating epoxy functional film is ground off to obtain a wafer.

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