Linear-buried adhesive film as well as preparation method and application thereof

Abstract

The invention provides a buried wire type adhesive film as well as a preparation method and application thereof. The adhesive film is prepared from the following raw material components: 25 to 40 parts of powder, 15 to 30 parts of phenoxy resin, 20 to 30 parts of bisphenol F type epoxy resin, 10 to 15 parts of dicyclopentadiene phenol epoxy resin, 5 to 10 parts of bisphenol F type benzoxazine, 3 to 8 parts of core-shell type acrylic acid powder, 2 to 5 parts of curing agent and 0.2 to 0.6 part of accelerant. The buried line type adhesive film is applied to a chip stacking structure and serves as a spacing material between adjacent chip layers, the buried line type adhesive film can accurately control the thickness of the material and has a good lead bonding effect, use of an isolation silicon wafer is eliminated, and the packaging process can be simplified. And meanwhile, good fluidity is achieved, resin seepage cannot occur in the bonding process, a good embedding effect on the lead is achieved, the problem that the chip is prone to inclination is solved, high reliability is achieved after lead bonding, and high-yield assembly can be achieved.

Description

Technical Field

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

[0002] At present, chip stacking structure has become the main form of three-dimensional electronic packaging, which stacks two or more functional chips in the same package. Figure 1 The traditional structure shown requires a layer of silicon wafer as a dummy chip between two layers of functional chips, or a spacer layer to achieve the space required for wire bonding. However, as the wafer becomes thinner, problems such as chip cracking and wire deformation occur during the bonding process. To solve this problem, Figure 2 The chip stacking structure shown utilizes an adhesive film that serves as both a spacer and wire embedding layer for wire embedding packaging. Film Over Wire (FOW) adhesive film directly stacks one functional chip on top of another. The film used for this purpose must prevent wire deformation during chip bonding and effectively fill the surrounding wires. It must exhibit excellent fluidity and wire embedding properties, along with comparable processability and reliability to traditional films. FOW packaging technology innovates by replacing silicon wafers with wire-embedding adhesive film, simplifying the packaging process, reducing the thickness of the plastic package, saving space, and adapting to market developments. Based on this understanding, the present invention proposes to optimize the formulation and develop a wire-embedding chip adhesive film with excellent fluidity and reliability for use in FOW packaging processes. Summary of the Invention

[0003] In view of the problems existing in the prior art, the present invention adopts the following technical solutions to solve the problems existing in the prior art: A wire-embedding adhesive film comprises the following raw materials: 25-40 parts of powder, 15-30 parts of phenoxy resin, 20-30 parts of bisphenol F epoxy resin, 10-15 parts of dicyclopentadiene phenol epoxy resin, 5-10 parts of bisphenol F benzoxazine, 3-8 parts of core-shell acrylic powder, 2-5 parts of curing agent, and 0.2-0.6 parts of accelerator.

[0004] The powder is spherical silicon dioxide (silicon powder) with an average particle size of 5-10 μm. It belongs to fused silicon dioxide and is used to change the modulus of the material.

[0005] The phenoxy resin is used as the main film-forming agent to improve the toughness of the film. Specifically, JER-1256 from Mitsubishi Chemical of Japan can be used. It is a benzene ring type crystalline high molecular weight epoxy resin. Toughening groups are introduced into the molecular chain segments, which has good toughness. It has an epoxy equivalent weight of 7800 g / eq and a molecular weight of 51000. The specific chemical formula is as follows: .

[0006] The bisphenol F epoxy resin is a liquid resin used to adjust the modulus of the material. Low total chlorine content can improve reliability. It has the advantages of good chemical stability and low viscosity. It can react with a variety of curing agents. Specifically, YL983U (epoxy equivalent 169 g / eq, total chlorine 300 ppm) produced by Mitsubishi Chemical of Japan can be used.

[0007] The dicyclopentadiene phenol epoxy resin has the advantages of low water absorption and high temperature resistance, and is used to reduce the water absorption rate of the material and improve the reliability and chemical stability of the material. Specifically, HP-7200 / HP-7200H (epoxy equivalent 250-280 g / eq, 265-300 g / eq) from DIC Corporation of Japan can be used. The chemical formula is as follows: .

[0008] The bisphenol F-type benzoxazine has the advantages of low hygroscopicity, high heat resistance, and flame retardancy, and can be used as a polymer curing agent to adjust the material modulus, reduce the water absorption rate of the material, and improve the reliability of the material. Specifically, BZ4100 (gel time 300-900s, Tg>170°C) produced by Puyang Enying Polymer Materials Co., Ltd. can be used.

[0009] The core-shell acrylic powder is used to improve the toughness of the material, increase adhesion, and improve reliability. The primary particle size in the powder is 0.1 to several microns. The core is acrylic rubber or silicone acrylic rubber, the shell is an acrylic copolymer, and the secondary particle size is 30-100μm. Specifically, Mitsubishi Chemical's LP4200 can be used.

[0010] The curing agent is used to react with the resin at a certain temperature to generate a thermosetting polymer. A latent curing agent, dicyandiamide, can be used, with an active hydrogen equivalent of 21 g / eq.

[0011] The accelerator is an imidazole accelerator, which is used to promote the cross-linking reaction and accelerate the curing. Specifically, 2-methylimidazole (2PHZ) can be used.

[0012] The preparation method of the embedded wire adhesive film is specifically as follows: first, using the solvent propylene glycol methyl ether acetate (PMA) to fully dissolve phenoxy resin, bisphenol F type benzoxazine resin, and dicyclopentadiene phenol epoxy resin at 140°C according to mass parts, then adding liquid bisphenol F type epoxy resin according to mass parts, and after fully dissolving and mixing evenly, adding core-shell acrylic powder while stirring, after mixing evenly, weighing silica powder and adding it, and then adding powdered curing agent and accelerator. After mixing evenly in a homogenizer, it is ground three times with a bead mill to obtain a uniform slurry, which is then vacuum degassed and coated with a coater. After the reaction is complete, the embedded wire chip adhesive film (FOW) is obtained.

[0013] The embedded wire adhesive film is used in a chip stacking structure as a spacer material between adjacent chip layers, that is, a stacking structure in which one chip is stacked on top of another, and one layer of embedded wire adhesive film is stacked on top of another. The chip leads are embedded in the film layer during the stacking process.

[0014] The present invention has the following advantages: Embedded wire adhesive films allow for precise control of material thickness, resulting in excellent wire bonding performance, eliminating the need for spacer silicon wafers and simplifying the packaging process. They also exhibit excellent flowability, preventing resin bleed during bonding and effectively embedding wires, addressing chip tilt issues. Furthermore, they offer high reliability after wire bonding, enabling high-yield assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a traditional chip stacking structure; Figure 2 It is a chip stacking structure using a buried wire adhesive film; Among them: 1-spacer layer, 2-dummy chip, 3-thin film between chip and substrate, 4-wire embedding film. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further specifically described below through examples.

[0017] Example 1 The raw materials of this embodiment include: 30 parts of spherical silica, 20 parts of JER-1256 phenoxy resin, 30 parts of YL983U bisphenol F epoxy resin, 10 parts of HP-7200H dicyclopentadiene phenol epoxy resin, 8 parts of BZ4100 bisphenol F benzoxazine, 6 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.3 parts of 2-methylimidazole.

[0018] Example 2 The raw materials of this embodiment include: 25 parts of spherical silica, 30 parts of JER-1256 phenoxy resin, 25 parts of YL983U bisphenol F epoxy resin, 13 parts of HP-7200H dicyclopentadiene phenol epoxy resin, 8 parts of BZ4100 bisphenol F benzoxazine, 6 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.4 parts of 2-methylimidazole.

[0019] Example 3 The raw materials of this embodiment include: 30 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 30 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200 dicyclopentadiene phenol epoxy resin, 10 parts of BZ4100 bisphenol F benzoxazine, 6 parts of LP4200 core-shell acrylic acid powder, 5 parts of dicyandiamide, and 0.4 parts of 2-methylimidazole.

[0020] Example 4 The raw materials of this embodiment include: 35 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 30 parts of YL983U bisphenol F epoxy resin, 13 parts of HP-7200H dicyclopentadiene phenol epoxy resin, 10 parts of BZ4100 bisphenol F benzoxazine, 7 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.5 parts of 2-methylimidazole.

[0021] Example 5 The raw materials of this embodiment include: 25 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 30 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200 dicyclopentadiene phenol epoxy resin, 10 parts of BZ4100 bisphenol F benzoxazine, 8 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.5 parts of 2-methylimidazole.

[0022] Example 6 The raw materials of this embodiment include: 30 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 30 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200 dicyclopentadiene phenol epoxy resin, 10 parts of BZ4100 bisphenol F benzoxazine, 8 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.5 parts of 2-methylimidazole.

[0023] Example 7 The raw materials of this embodiment include: 35 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 30 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200H dicyclopentadiene phenol epoxy resin, 8 parts of BZ4100 bisphenol F benzoxazine, 8 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.5 parts of 2-methylimidazole.

[0024] Comparative Example 1 The raw materials of this comparative example include: 25 parts of spherical silica, 40 parts of JER-1256 phenoxy resin, 25 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200 dicyclopentadiene phenol epoxy resin, 8 parts of BZ4100 bisphenol F benzoxazine, 2 parts of LP4200 core-shell acrylic powder, 4 parts of dicyandiamide, and 0.2 parts of 2-methylimidazole.

[0025] Comparative Example 2 The raw materials of this comparative example include: 20 parts of spherical silica, 20 parts of JER-1256 phenoxy resin, 25 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200H dicyclopentadiene phenol epoxy resin, 10 parts of BZ4100 bisphenol F benzoxazine, 5 parts of LP4200 core-shell acrylic powder, 4 parts of dicyandiamide, and 0.4 parts of 2-methylimidazole.

[0026] Comparative Example 3 The raw materials of this comparative example include: 20 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 30 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200H dicyclopentadiene phenol epoxy resin, 8 parts of BZ4100 bisphenol F benzoxazine, 5 parts of LP4200 core-shell acrylic powder, 4 parts of dicyandiamide, and 0.4 parts of 2-methylimidazole.

[0027] Comparative Example 4 The raw materials of this comparative example include: 30 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 35 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200 dicyclopentadiene phenol epoxy resin, 10 parts of BZ4100 bisphenol F benzoxazine, 10 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.5 parts of 2-methylimidazole.

[0028] Comparative Example 5 The raw materials of this embodiment include: 30 parts of spherical silica, 25 parts of JER-1256 phenoxy resin, 25 parts of YL983U bisphenol F epoxy resin, 15 parts of HP-7200 dicyclopentadiene phenol epoxy resin, 10 parts of BZ4100 bisphenol F benzoxazine, 10 parts of LP4200 core-shell acrylic powder, 5 parts of dicyandiamide, and 0.5 parts of 2-methylimidazole.

[0029] The above examples and comparative examples were all prepared by the following method: first, propylene glycol methyl ether acetate solvent was used to fully dissolve phenoxy resin, bisphenol F type benzoxazine resin, and dicyclopentadiene phenol epoxy resin at 140°C in parts by mass, and then liquid bisphenol F type epoxy resin was added in parts by mass. After fully dissolved and mixed, core-shell acrylic powder was added while stirring. After mixing, silica powder was weighed and added, and then powdered curing agent and accelerator were added. After mixing evenly in a homogenizer, the mixture was ground three times in a bead mill to obtain a uniform slurry, which was then vacuum degassed and coated with a coater. After the reaction was complete, an embedded wire chip adhesive film was obtained.

[0030] The embedded wire adhesive films provided in Examples 1-7 and Comparative Examples 1-5 were tested for post-curing tensile strength, elongation at break, 50°C storage modulus, glass transition temperature, 5% thermal weight loss temperature, elevated temperature rheological viscosity, ion content, silicon wafer adhesion, and water absorption. The specific testing methods are as follows: 1. Membrane tensile strength and elongation at break: Cut the membrane material into 10 mm × 80 mm pieces, tear off the light release membrane, stick the two ends of the specimen with tape, clamp the tape at both ends of the universal material testing machine, and then tear off the heavy release membrane to test the tensile strength and elongation at break of the membrane.

[0031] 2. DMA measurement of storage modulus and Tg: Referring to the standard "ASTM E2254-2018 Test Method for Determination of Storage Modulus by Dynamic Mechanical Analyzer", the film was made into a 30mm×6mm×0.24mm specimen, cured at 165℃ for 2h, and heated to 250℃ at a heating rate of 5℃ / min. In tensile mode, the storage modulus at 50℃ was taken, and the glass transition temperature Tg value was read.

[0032] 3. Rheological viscosity at elevated temperature: 20 layers of 50 μm thick FOW film were applied to form a disc with a thickness of 1 mm and a diameter of 20 mm. The test mode was an oscillation temperature ramp with a heating rate of 5°C / min. The temperature was raised from 50°C to 160°C, and the viscosity value at 120°C was taken.

[0033] 4. 5-part weight loss temperature: Use a thermogravimetric analyzer (TGA) to measure, set the heating rate to 10℃ / min, raise the temperature to 600℃, measure in air atmosphere, and read the temperature at the time of 5-part weight loss on the thermogravimetric curve.

[0034] 5. Ion content test: refer to the standard "IPC-TM-650 2.3.28B Circuit Board Ion Analysis Ion Chromatography", use ion chromatograph to measure the ultrapure water extract of the cured membrane material (120 ℃ × 24 h extraction), the mobile phase is 2.4 mM Na2CO3 + 6.0 mM NaHCO3, the flow rate is 1.2 mL / min, and Cl - , Na + and K + content.

[0035] 6. Shear Strength Test: A 50μm thick embedded wire die-attachment film (FOW) was attached to a 10 mm × 10 mm silicon wafer, and then a 2 mm × 2 mm silicon wafer was attached to the film. After curing at 165°C for 2 hours, the shear strength was measured using a multi-function thruster with the blade height set to 30μm and the speed set to 50μm / s. The adhesion of the silicon wafer before treatment at 85°C and 85% humidity was measured at room temperature (85 / 85 × 0h) and after treatment at 85°C and 85% humidity for 24 hours (85 / 85 × 24h).

[0036] 7. Water Absorption: Three 20 mm × 20 mm × 1 mm membranes were cured at 165°C for 2 h. The initial mass after curing was weighed. The membranes were then placed in a high-pressure, high-temperature retort (PCT) at 120°C for 24 h. Afterwards, the membranes were dried and weighed sequentially. The water absorption was then calculated and the average value was taken.

[0037] The product performance test data of the above embodiments and comparative examples are shown in Table 1.

[0038] Table 1 Raw material components and test results by mass in Examples 1-7 and Comparative Examples 1-5 From the test results in Table 1, we can see that: (1) Although comparative examples 1-5 use phenoxy resin, bisphenol F epoxy resin and dicyclopentadiene phenol epoxy resin as the main resin, core-shell acrylic powder for toughening, and bisphenol F benzoxazine and dicyandiamide as curing agents, the addition range is outside the specific ratio of the present invention. Therefore, the tensile strength and elongation of the prepared films are low, and the storage modulus and water absorption rate are high. The viscosity and silicon wafer adhesion are low, which is insufficient to stably bond the chip and prevent the chip from tilting. The bonding process cannot well embed the wire, resulting in poor reliability of the packaged chip. (2) Comparative Example 1 used the lowest content of core-shell acrylic powder, while Comparative Example 4 used the highest content of acrylic powder. Both of these contents were outside the specified ratio. The tensile strength and elongation of the films prepared were relatively low, while the films prepared in Examples 1-7 had excellent mechanical properties, indicating that acrylic powder needs to be used within a specific ratio to achieve a toughening effect. (3) Comparative Example 1 uses a higher content of phenoxy resin, resulting in a higher film modulus. Compared with Comparative Example 4 and Example 3, the use of too high a content of bisphenol F epoxy resin will result in excessive chloride ion content, affecting reliability. Compared with Example 2 and Example 3, adding dicyclopentadiene phenol epoxy resin and bisphenol F benzoxazine resin helps to reduce water absorption and improve the reliability of the packaged chip. (4) Examples 1-7 use core-shell acrylic powder in appropriate proportions for toughening, dicyclopentadiene phenol epoxy resin and bisphenol F benzoxazine resin for reducing water absorption, and phenoxy resin and low-chloride bisphenol F epoxy resin for adjusting the modulus. Within a specific proportion range, the comprehensive performance of the film meets the requirements, and the film has appropriate fluidity, can effectively embed wires, bond chips, and has good packaging reliability.

[0039] The scope of protection of the present invention is not limited to the above-described embodiments. Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the scope and spirit of the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A thread-embedding adhesive film, characterized in that: The raw materials include the following components: 25-40 parts of powder, 15-30 parts of phenoxy resin, 20-30 parts of bisphenol F epoxy resin, 10-15 parts of dicyclopentadiene phenol epoxy resin, 5-10 parts of bisphenol F benzoxazine, 3-8 parts of core-shell acrylic powder, 2-5 parts of curing agent, and 0.2-0.6 parts of accelerator.

2. The wire-embedding adhesive film according to claim 1, wherein: The powder is spherical silicon dioxide with a particle size of 5-10 μm.

3. The wire-embedding adhesive film according to claim 1, wherein: The phenoxy resin is JER-1256 benzene ring type crystalline high molecular weight epoxy resin with an epoxy equivalent of 7800 g / eq and a molecular weight of 51000.

4. The wire-embedding adhesive film according to claim 1, wherein: The bisphenol F epoxy resin is YL983U type, with an epoxy equivalent of 169 g / eq and a total chlorine content of 300 ppm.

5. The wire-embedding adhesive film according to claim 1, wherein: The dicyclopentadiene phenol epoxy resin is of HP-7200 type or HP-7200H type, with an epoxy equivalent of 250-280 g / eq or 265-300 g / eq.

6. The wire-embedding adhesive film according to claim 1, wherein: The bisphenol F-type benzoxazine is BZ4100, with a gel time of 300-900s and a Tg>170°C.

7. The wire-embedding adhesive film according to claim 1, wherein: The primary particle size of the core-shell acrylic powder is 0.1 to several microns, the core is acrylic rubber or silicone acrylic rubber, the shell is acrylic copolymer, the secondary particle size is 30-100 μm, and LP4200 core-shell acrylic powder is used.

8. The wire-embedding adhesive film according to claim 1, wherein: The curing agent is a latent curing agent dicyandiamide, with an active hydrogen equivalent of 21 g / eq. The accelerator is an imidazole accelerator, specifically 2-methylimidazole.

9. The method for preparing a wire-embedded adhesive film according to any one of claims 1 to 8, wherein: Specifically, the process includes the following steps: first, using the solvent propylene glycol methyl ether acetate to fully dissolve phenoxy resin, bisphenol F type benzoxazine resin, and dicyclopentadiene phenol epoxy resin at 140°C according to mass fractions, then adding liquid bisphenol F type epoxy resin according to mass fractions, fully dissolving and mixing evenly, then adding core-shell acrylic powder while stirring, mixing evenly, weighing silica powder and adding it, and then adding powdered curing agent and accelerator, mixing evenly with a homogenizer, and then grinding with a bead mill three times to obtain a uniform slurry, which is then vacuum degassed and coated with a coater. After the reaction is complete, an embedded wire chip adhesive film is obtained.

10. Use of the wire embedding adhesive film according to any one of claims 1 to 8, characterized in that: The embedded wire adhesive film is used in a chip stacking structure as a spacer material between adjacent chip layers, that is, a stacking structure in which one chip is stacked on top of another, and one layer of embedded wire adhesive film is stacked on top of another. The chip leads are embedded in the film layer during the stacking process.

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