A buried wire type adhesive film and a preparation method and application thereof

Abstract

The application provides a buried wire type adhesive film and a preparation method and application thereof. Raw materials of the adhesive film comprise the following components: 25-40 parts of powder, 15-30 parts of phenoxy resin, 20-30 parts of bisphenol F type epoxy resin, 10-15 parts of dicyclopentadiene phenol epoxy resin, 5-10 parts of bisphenol F type benzoxazine, 3-8 parts of core-shell type acrylic powder, 2-5 parts of curing agent and 0.2-0.6 parts of accelerator. The buried wire type adhesive film is applied in a chip stacking structure as a spacing material between adjacent chip layers. The buried wire type adhesive film can accurately control the material thickness, has good wire bonding effect, eliminates the use of isolation silicon chips and can simplify the packaging process. Meanwhile, the buried wire type adhesive film has good fluidity, does not appear resin bleeding in the bonding process, has good embedding effect on the wire, solves the problem that the chip is easy to tilt, has high reliability after wire bonding and can realize high-yield assembly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chip packaging, and particularly relates to a buried wire type adhesive film and a preparation method and application thereof. BACKGROUND

[0002] At present, a chip stacking structure has become a main form of three-dimensional electronic packaging, and two or more functional chips are stacked in a same packaging body. Figure 1 As shown in a conventional structure, a layer of silicon wafer is pasted between two layers of functional chips as a dummy chip, or a spacing layer is used to realize a space required for wire bonding, but with the thinning of the wafer, problems such as chip cracking and wire deformation occur in the bonding process. Figure 2 As shown in a chip stacking structure, an adhesive film with spacing layer and buried wire functions is used for wire embedding packaging. The Film Over Wire (FOW) is directly used for stacking one functional chip on another functional chip, and the film used for this purpose needs to ensure that the wire does not deform and is well filled around the wire during chip bonding, needs to have good fluidity and wire embedding property, and needs to have processability, reliability and other properties comparable to conventional films. SUMMARY

[0003] In view of the problems in the prior art, the technical scheme adopted by the application to solve the problems in the prior art is as follows:

[0004] A buried wire type adhesive film, raw materials of which include the following components: 25-40 parts of powder, 15-30 parts of phenoxy resin, 20-30 parts of bisphenol F type epoxy resin, 10-15 parts of dicyclopentadiene phenol epoxy resin, 5-10 parts of bisphenol F type benzoxazine, 3-8 parts of core-shell type acrylic powder, 2-5 parts of curing agent, and 0.2-0.6 parts of accelerator.

[0005] The powder is spherical silica (silica powder), the average particle size of which is 5-10 microns, and it is a fused silica used for changing the modulus of the material.

[0006] The phenoxy resin is used as a main film former for improving the toughness of the film, and specifically, JER-1256 of Mitsubishi Chemical of Japan can be used, which is a benzene ring type crystalline high molecular weight epoxy resin, a toughness group is introduced into the molecular chain segment, it has good toughness, the epoxy equivalent is 7800 g / eq, the molecular weight is 51000, and the specific chemical formula is as follows: .

[0007] The bisphenol F type epoxy resin is a liquid resin, used to adjust the modulus of the material, and low total chlorine can improve reliability, has the advantages of good chemical stability, small viscosity, etc., can react with various curing agents, and specifically YL983U (epoxy equivalent 169 g / eq, total chlorine 300 ppm) of Mitsubishi Chemical of Japan can be used.

[0008] The dicyclopentadiene phenol epoxy resin has the advantages of low water absorption and high temperature resistance, and is used to reduce the water absorption of the material, improve the reliability and chemical stability of the material, and specifically HP-7200 / HP-7200H (epoxy equivalent 250-280 g / eq, 265-300 g / eq) of DIC Corporation of Japan can be used, and the chemical formula is as follows:

[0009] .

[0010] The bisphenol F type benzoxazine has the advantages of low moisture absorption, high heat resistance and flame retardance, and can be used as a high molecular curing agent to adjust the modulus of the material, reduce the water absorption of the material, and improve the reliability of the material, and specifically BZ4100 (gel time 300-900 s, Tg> 170 ℃) of Puyang Enying High Polymer Material Co., Ltd. can be used.

[0011] The core-shell type acrylic powder is used to improve the toughness of the material, increase the adhesion, and improve the reliability, the primary particle size of the powder is 0.1 to several microns, the core is acrylic rubber or silicone acrylic rubber, the shell is acrylic copolymer, and the secondary particle size is 30-100 μm, and specifically LP4200 of Mitsubishi Chemical can be used.

[0012] The curing agent is used to react with the resin at a certain temperature to generate a thermosetting polymer, and a latent curing agent dicyandiamide can be used, and the active hydrogen equivalent is 21 g / eq.

[0013] The accelerator is an imidazole type accelerator, used to promote crosslinking reaction and accelerate curing, and specifically 2-methylimidazole (2PHZ) can be used.

[0014] The preparation method of the buried wire type adhesive film is specifically as follows: first, the phenoxy resin, bisphenol F type benzoxazine resin, and dicyclopentadiene phenol epoxy resin are fully dissolved in the solvent propylene glycol methyl ether acetate (PMA) at 140 ℃ according to the mass fraction, then the liquid bisphenol F type epoxy resin is added according to the mass fraction, fully dissolved, mixed uniformly, then the core-shell type acrylic powder is added while stirring, mixed uniformly, then the silica powder is weighed and added, then the powdered curing agent and accelerator are added, uniformly mixed by a homogenizer, then the uniform slurry is obtained by grinding three times with a bead mill, then vacuum degassing and coating are performed, and the buried wire type chip adhesive film (FOW) is obtained after the reaction is completed.

[0015] The buried wire type adhesive film is applied in a chip stacking structure as a spacing material between adjacent chip layers, i.e. a layer of chips-a layer of buried wire type adhesive film-a layer of chips, a stacking structure stacked in sequence, wherein the chip leads are buried in the film layer during stacking.

[0016] The present application has the following advantages:

[0017] The buried wire type adhesive film can precisely control the thickness of the material, has good lead bonding effect, eliminates the use of isolation silicon chips, and can simplify the packaging process. At the same time, it has good fluidity, and resin exudation does not occur during the bonding process, has good embedding effect on the leads, solves the problem of easy tilting of the chip, and has high reliability after lead bonding, and can realize high-yield assembly. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 for the traditional chip stacking structure;

[0019] Figure 2 for the chip stacking structure using the buried wire type adhesive film;

[0020] Wherein: 1 - spacing layer, 2 - dummy chip, 3 - film between chip and substrate, 4 - buried wire film. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be further specifically described below through examples.

[0022] Example 1

[0023] The raw materials of this example include: spherical silica 30 parts, JER-1256 type phenoxy resin 20 parts, YL983U type bisphenol F type epoxy resin 30 parts, HP-7200H type dicyclopentadiene phenol epoxy resin 10 parts, BZ4100 type bisphenol F type benzoxazine 8 parts, LP4200 type core-shell type acrylic powder 6 parts, dicyandiamide 5 parts, 2-methyl imidazole 0.3 parts.

[0024] Example 2

[0025] The raw materials of this example include: spherical silica 25 parts, JER-1256 type phenoxy resin 30 parts, YL983U type bisphenol F type epoxy resin 25 parts, HP-7200H type dicyclopentadiene phenol epoxy resin 13 parts, BZ4100 type bisphenol F type benzoxazine 8 parts, LP4200 type core-shell type acrylic powder 6 parts, dicyandiamide 5 parts, 2-methyl imidazole 0.4 parts.

[0026] Example 3

[0027] The raw materials of this example include: spherical silica 30 parts, JER-1256 type phenoxy resin 25 parts, YL983U type bisphenol F type epoxy resin 30 parts, HP-7200 type dicyclopentadiene phenol epoxy resin 15 parts, BZ4100 type bisphenol F type benzoxazine 10 parts, LP4200 type core-shell acrylic powder 6 parts, dicyandiamide 5 parts, 2-methylimidazole 0.4 parts.

[0028] Example 4

[0029] The raw materials of this example include: spherical silica 35 parts, JER-1256 type phenoxy resin 25 parts, YL983U type bisphenol F type epoxy resin 30 parts, HP-7200H type dicyclopentadiene phenol epoxy resin 13 parts, BZ4100 type bisphenol F type benzoxazine 10 parts, LP4200 type core-shell acrylic powder 7 parts, dicyandiamide 5 parts, 2-methylimidazole 0.5 parts.

[0030] Example 5

[0031] The raw materials of this example include: spherical silica 25 parts, JER-1256 type phenoxy resin 25 parts, YL983U type bisphenol F type epoxy resin 30 parts, HP-7200 type dicyclopentadiene phenol epoxy resin 15 parts, BZ4100 type bisphenol F type benzoxazine 10 parts, LP4200 type core-shell acrylic powder 8 parts, dicyandiamide 5 parts, 2-methylimidazole 0.5 parts.

[0032] Example 6

[0033] The raw materials of this example include: spherical silica 30 parts, JER-1256 type phenoxy resin 25 parts, YL983U type bisphenol F type epoxy resin 30 parts, HP-7200 type dicyclopentadiene phenol epoxy resin 15 parts, BZ4100 type bisphenol F type benzoxazine 10 parts, LP4200 type core-shell acrylic powder 8 parts, dicyandiamide 5 parts, 2-methylimidazole 0.5 parts.

[0034] Example 7

[0035] The raw materials of this example include: spherical silica 35 parts, JER-1256 type phenoxy resin 25 parts, YL983U type bisphenol F type epoxy resin 30 parts, HP-7200H type dicyclopentadiene phenol epoxy resin 15 parts, BZ4100 type bisphenol F type benzoxazine 8 parts, LP4200 type core-shell acrylic powder 8 parts, dicyandiamide 5 parts, 2-methylimidazole 0.5 parts.

[0036] Comparative Example 1

[0037] The raw materials of the present comparative example include: spherical silica 25 parts, phenoxy resin of JER-1256 type 40 parts, bisphenol F type epoxy resin of YL983U type 25 parts, dicyclopentadiene phenol epoxy resin of HP-7200 type 15 parts, bisphenol F type benzoxazine of BZ4100 type 8 parts, core-shell type acrylic powder of LP4200 type 2 parts, dicyandiamide 4 parts, 2-methylimidazole 0.2 parts.

[0038] Comparative Example 2

[0039] The raw materials of the present comparative example include: spherical silica 20 parts, phenoxy resin of JER-1256 type 20 parts, bisphenol F type epoxy resin of YL983U type 25 parts, dicyclopentadiene phenol epoxy resin of HP-7200H type 15 parts, bisphenol F type benzoxazine of BZ4100 type 10 parts, core-shell type acrylic powder of LP4200 type 5 parts, dicyandiamide 4 parts, 2-methylimidazole 0.4 parts.

[0040] Comparative Example 3

[0041] The raw materials of the present comparative example include: spherical silica 20 parts, phenoxy resin of JER-1256 type 25 parts, bisphenol F type epoxy resin of YL983U type 30 parts, dicyclopentadiene phenol epoxy resin of HP-7200H type 15 parts, bisphenol F type benzoxazine of BZ4100 type 8 parts, core-shell type acrylic powder of LP4200 type 5 parts, dicyandiamide 4 parts, 2-methylimidazole 0.4 parts.

[0042] Comparative Example 4

[0043] The raw materials of the present comparative example include: spherical silica 30 parts, phenoxy resin of JER-1256 type 25 parts, bisphenol F type epoxy resin of YL983U type 35 parts, dicyclopentadiene phenol epoxy resin of HP-7200 type 15 parts, bisphenol F type benzoxazine of BZ4100 type 10 parts, core-shell type acrylic powder of LP4200 type 10 parts, dicyandiamide 5 parts, 2-methylimidazole 0.5 parts.

[0044] Comparative Example 5

[0045] The raw materials of the present example include: spherical silica 30 parts, phenoxy resin of JER-1256 type 25 parts, bisphenol F type epoxy resin of YL983U type 25 parts, dicyclopentadiene phenol epoxy resin of HP-7200 type 15 parts, bisphenol F type benzoxazine of BZ4100 type 10 parts, core-shell type acrylic powder of LP4200 type 10 parts, dicyandiamide 5 parts, 2-methylimidazole 0.5 parts.

[0046] The above examples and comparative examples are prepared by the following method: first, the phenoxy resin, bisphenol F type benzoxazine resin, and dicyclopentadiene phenol epoxy resin are fully dissolved in the solvent propylene glycol methyl ether acetate at 140 °C according to the mass fraction, then the liquid bisphenol F type epoxy resin is added according to the mass fraction, and after fully dissolving and uniformly mixing, the core-shell type acrylic powder is added while stirring, and after uniformly mixing, the silica powder is weighed and added, then the powdered curing agent and accelerator are added, and uniformly mixed by a homogenizer, then ground by a bead mill for three times to obtain a uniform slurry, then vacuum degassing and coating by a coating machine, and after the reaction is completed, the buried wire type chip adhesive film is obtained.

[0047] The buried wire type adhesive film provided by Examples 1-7 and Comparative Examples 1-5 is tested for film tensile strength, film elongation at break, 50 °C storage modulus, glass transition temperature, 5% thermal weight loss temperature, temperature rising rheological viscosity, ion content, silicon wafer adhesion, and water absorption after curing, and the specific test methods are as follows:

[0048] 1. Film tensile strength and elongation at break: cut the film material into 10 mm x 80 mm, tear off the light-off 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 heavy-off film, and test the tensile strength and elongation at break of the film.

[0049] 2. DMA storage modulus and Tg: refer to the standard “ASTM E2254-2018 Dynamic Mechanical Analyzer Storage Modulus Test Method”, prepare a sample of 30 mm x 6 mm x 0.24 mm from the film, cure at 165 °C for 2 h, heat to 250 °C at a heating rate of 5 °C / min, use the tensile mode, take the storage modulus at 50 °C, and read the glass transition temperature Tg value.

[0050] 3. Temperature rising rheological viscosity: paste 20 layers of FOW film with a thickness of 50 μm to prepare a circular piece with a thickness of 1 mm and a diameter of 20 mm, select the oscillation mode temperature change (Oscillation Temperature Ramp) as the test mode, set the heating rate to 5 °C / min, and heat from 50 °C to 160 °C, and take the viscosity value at 120 °C.

[0051] 4. 5% thermal weight loss temperature: measured by a thermal gravimetric analyzer (TGA), set the heating rate to 10 °C / min, heat to 600 °C, measure in an air atmosphere, and read the temperature at the time of 5% weight loss on the thermal gravimetric curve.

[0052] 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 content of Cl - , Na + and K + in the ultrapure water extract (120℃ x 24 h extraction) of the cured film material, the mobile phase is 2.4 mM Na2CO3+6.0 mM NaHCO3, the flow rate is 1.2 mL / min.

[0053] 6. Shear strength test: paste the 50 μm thick buried wire type chip adhesive film (FOW) on the 10 mm x 10 mm silicon wafer, then paste the 2 mm x 2 mm silicon wafer on the film, cure at 165℃ for 2 h, then use the multifunctional thrust machine to measure the shear strength, the push knife height is set to 30 μm, the speed is 50 μm / s, measure the silicon wafer adhesion force (85 / 85 x 0 h) without 85℃, 85 humidity treatment and the silicon wafer adhesion force (85 / 85 x 24 h) after 85℃, 85 humidity treatment for 24 h at room temperature.

[0054] 7. Water absorption: take 20 mm x 20 mm x 1 mm film material 3, cure, curing condition: 165℃ / 2 h. Weigh the initial mass after curing, then place in the high temperature and pressure cooker (PCT) at 120℃ for 24 h, after finishing, wipe the surface moisture of the film, weigh in turn, then calculate the water absorption, then take the average value.

[0055] The product performance test data of the above examples and comparative examples are shown in Table 1.

[0056] Table 1. The mass fraction of each raw material component and test results in examples 1-7 and comparative examples 1-5

[0057]

[0058] From the test results in Table 1, it can be seen that:

[0059] (1) Comparative examples 1-5 use phenoxy resin, bisphenol F type epoxy resin and dicyclopentadiene phenol epoxy resin as the main resin, core-shell type acrylic acid powder toughening, bisphenol F type benzoxazine and dicyandiamide as the curing agent, but the addition range is outside the specific ratio of the application, so the tensile strength and elongation of the prepared film are low, the storage modulus and water absorption are high, the viscosity and silicon wafer adhesion are low, which is not enough to stably bond the chip, avoid the chip tilt, the bonding process cannot well embed the wire, leading to poor reliability of the packaged chip;

[0060] (2) The core-shell acrylic powder used in Comparative Example 1 has the lowest content, and the acrylic powder used in Comparative Example 4 has the highest content, and neither of them is within the specific ratio, and the tensile strength and elongation of the prepared film are both low, while the mechanical properties of the films prepared in Examples 1-7 are excellent, which shows that the acrylic powder needs to be used within a specific ratio range to achieve toughening effect;

[0061] (3) The content of phenoxy resin used in Comparative Example 1 is relatively high, which leads to high modulus of the film, compared with Comparative Example 4 and Example 3, the use of high content of bisphenol F type epoxy resin will lead to excessive chloride ion content, affecting the reliability, compared with Example 2 and Example 3, the increase of dicyclopentadiene phenol epoxy resin and bisphenol F type benzoxazine resin helps to reduce the water absorption rate, which can improve the reliability of the packaged chip;

[0062] (4) Examples 1-7 use appropriate proportions of core-shell acrylic powder toughening, dicyclopentadiene phenol epoxy resin and bisphenol F type benzoxazine resin to reduce water absorption, phenoxy resin and low-chlorine bisphenol F type epoxy resin to adjust modulus, and within a specific ratio range, the comprehensive performance of the film meets the requirements, the film has appropriate fluidity, can effectively embed the lead wire, bond the chip, and has good packaging reliability.

[0063] The scope of protection of the present application is not limited to the above-mentioned examples, and obviously, those skilled in the art can make various modifications and changes to the present application without departing from the scope and spirit of the present application. If these modifications and changes belong to the scope of the claims of the present application and its equivalent technologies, the intention of the present application also includes these modifications and changes.

Claims

1. An adhesive tape having a wire embedded therein, characterized by: The raw materials include the following components: 25-40 parts of powder, 15-30 parts of phenoxy resin, 20-30 parts of bisphenol F type epoxy resin, 10-15 parts of dicyclopentadiene phenol epoxy resin, 5-10 parts of bisphenol F type benzoxazine, 3-8 parts of core-shell acrylic powder, 2-5 parts of curing agent, and 0.2-0.6 parts of accelerator; The core-shell acrylic powder is LP4200 type core-shell acrylic powder; The powder is spherical silica with a particle size of 5-10 μm; The phenoxy resin is JER-1256 benzene ring type crystalline high molecular weight epoxy resin with a molecular weight of 51000; The bisphenol F type epoxy resin is YL983U type with an epoxy equivalent weight of 169 g / eq and a total chlorine content of 300 ppm; The dicyclopentadiene phenol epoxy resin is HP-7200 type or HP-7200H type; The bisphenol F type benzoxazine is BZ4100 type with a Tg of > 170 ℃; The curing agent is latent curing agent dicyandiamide with an active hydrogen equivalent weight of 21 g / eq, and the accelerator is 2-methylimidazole.

2. The method for preparing a buried wire type adhesive film as described in claim 1, characterized in that, The method specifically includes the following steps: first, the phenoxy resin, bisphenol F type benzoxazine resin, and dicyclopentadiene phenol epoxy resin are dissolved in solvent propylene glycol methyl ether acetate at 140 ℃, then the liquid bisphenol F type epoxy resin is added, and the mixture is dissolved and mixed uniformly, then the core-shell acrylic powder is added while stirring, and the mixture is mixed uniformly, then the silica powder is weighed and added, then the powdered curing agent and accelerator are added, and the mixture is uniformly mixed in a homogenizer, then the mixture is ground three times in a bead mill to obtain a uniform slurry, then the slurry is vacuum degassed and coated by a coating machine, and after the reaction is completed, the buried wire type chip adhesive film is obtained.

3. Use of an adhesive film according to claim 1, wherein: The buried wire type adhesive film is applied in a chip stacking structure as a spacing material between adjacent chip layers, i.e., one layer of chip, one layer of buried wire type adhesive film, and one layer of chip, and the stacking structure is stacked in sequence, wherein the chip leads are buried in the film layer during stacking.

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