A reworkable toughened chip-level underfill adhesive and a preparation method thereof

Abstract

This invention relates to the field of adhesive technology, and particularly to a reworkable, toughened chip-level underfill adhesive and its preparation method. The underfill adhesive provided by this invention, by weight, comprises the following components: 15-25 parts bisphenol F epoxy resin, 3-8 parts self-synthesized tetraglycidyl ether containing furan groups, 0.5-2 parts bismaleimide resin, 0.5-1.5 parts silane coupling agent, 0.5-1.5 parts leveling agent, 0.5-1.5 parts black paste, 60-70 parts spherical silica powder, and 5-15 parts curing agent. This invention innovatively introduces tetraglycidyl ether containing furan groups, combined with bismaleimide resin, resulting in a cured product with high heat resistance, excellent flexibility, and reworkable properties.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and in particular to a reworkable toughened chip-level underfill adhesive and its preparation method. Background Technology

[0002] In chip packaging technology, the bonding layer between the IC chip and the organic substrate consists of numerous tiny solder joints. These joints have poor deformation adaptability and are extremely sensitive to thermal stress, making structural reliability issues more prominent. Using polymer underfill to improve the reliability of packaged chips is a commonly used method. This method is economical and easy to implement. During chip packaging, the underfill material gradually solidifies in the narrow gap between the IC chip and the organic substrate through thermosetting, protecting the connecting solder joints. It can also effectively mitigate impact loads, improve the packaged chip's resistance to deformation, moisture, and chemical corrosion, and significantly extend the fatigue life of the packaged chip, thus showing great development potential.

[0003] Chip-level underfill material contacts three parts: the upper chip, the middle bump (spacer balls), and the lower substrate. The bump material is typically metallic tin or an alloy of tin and other metals, with a low melting temperature. At rework temperatures, it easily melts and deforms, separating from the underfill material. However, the surfaces of the upper chip and the lower substrate have large contact areas with the underfill material, exhibiting strong adhesion. Rework temperatures are typically between 260-300℃. If the temperature is too low, the adhesion between the underfill material and the interface remains relatively high, easily damaging the chip and substrate during rework; if the temperature is too high, it may cause damage to the chip and substrate. Traditional chip-level underfill materials, due to their formulation characteristics, struggle to achieve the goal of being reworkable without damaging the chip and substrate. Summary of the Invention

[0004] To address the aforementioned technical problems in the prior art, this invention provides a reworkable toughened chip-level underfill adhesive and its preparation method.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0006] The first aspect of this invention provides a reworkable toughened chip-level underfill adhesive, comprising the following components by weight:

[0007] 15-25 parts of bisphenol F type epoxy resin, 3-8 parts of self-synthesized tetraglycidyl ether containing furan groups, 0.5-2 parts of bismaleimide resin, 0.5-1.5 parts of silane coupling agent, 0.5-1.5 parts of leveling agent, 0.5-1.5 parts of black paste, 60-70 parts of spherical silica powder, and 5-15 parts of curing agent.

[0008] The beneficial effects of the above technical solution are as follows: during the curing of the chip-level bottom filler adhesive, the imide groups in the bismaleimide resin combine with the furan groups in the tetraglycidyl ether containing furan groups to generate crosslinking points, forming a structure with a certain rigidity and the ability to withstand high temperatures; at the same time, when the temperature reaches 280℃-300℃, the crosslinking points of furan groups and imide groups can undergo reversible decomposition, directly affecting the interface bonding effect, which is conducive to interface delamination and thus achieves the effect of reworkability.

[0009] Based on the above technical solution, the present invention can also be improved in the following ways:

[0010] Furthermore, the tetraglycidyl ether containing the furan group is 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyldisiloxyl)]-tetraglycidyl ether.

[0011] The beneficial technical effects of adopting the above-mentioned further technical solution are as follows: The structure contains four epoxy groups, which have high reactivity and can fully react with the curing agent to form more crosslinking points, increase the crosslinking density, and provide higher heat resistance for the cured underfill adhesive; at the same time, the structure also contains rigid groups such as furan groups and benzene rings, which also provide heat resistance for the cured underfill adhesive; furthermore, the structure also contains 6 ether bonds and tetramethylsilane segments, which provide flexibility for the cured underfill adhesive. This flexibility can improve the reliability of chip packaging during thermal shock and high-temperature storage, and can also minimize the high-temperature modulus of the cured underfill adhesive at the rework temperature. The crosslinking points combined with furan groups and imide groups can undergo reversible decomposition synergistic effect, further reducing the difficulty of rework and achieving a reworkable effect.

[0012] Furthermore, the tetraglycidyl ether containing a furan group is prepared by the following method:

[0013] (1) Using α-furan carbaldehyde and 2-methoxy-4-(2-propenyl)phenol as the first-step reaction monomers, xylene as the solvent and methyl imidazole as the catalyst, a condensation reaction was carried out to obtain 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol (the structural formula is shown in formula (I));

[0014]

[0015] (2) Using 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol and epichlorohydrin as monomers in the second step reaction, and tetrabutylammonium bromide as a phase transfer catalyst, the ring-opening reaction yields the intermediate 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]propylchlorohydrin ether (structural formula shown in formula (II)). Sodium hydroxide is then added, and the ring-closing reaction yields 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether (structural formula shown in formula (III)).

[0016]

[0017] (3) Using 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether and tetramethyldihydrodisiloxane as the monomers for the third step reaction, a platinum catalyst was added, and 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyldihydrodisiloxane)]glycidyl ether (structural formula as shown in formula (Ⅳ)) was obtained by the first addition reaction.

[0018]

[0019] (4) Using 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-hydrodisiloxyl)] glycidyl ether and propenyl glycidyl ether as monomers in the fourth step reaction, a platinum catalyst was added, and a second addition reaction was carried out to obtain 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-disiloxyl)]-tetraglycidyl ether (abbreviated as tetraglycidyl ether containing furan group, abbreviated as TGEF, with the structural formula shown in formula (V)).

[0020]

[0021] Further, in step (1), the molar ratio of α-furanaldehyde to 2-methoxy-4-(2-propenyl)phenol is 1:1-1:5, the mass ratio of methylimidazolium to the monomer of the first step reaction is 0.1-10:100, and the mass ratio of xylene to the monomer of the first step reaction is 40-80:100. This is to ensure that the reaction is complete and thorough.

[0022] Further, in step (2), the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol to epichlorohydrin is 1:2-20, the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]propylchlorohydrin ether to sodium hydroxide is 1:2-10, and the mass ratio of tetrabutylammonium bromide to the monomer of the second step reaction is 0.1-2:100. This ensures a complete and thorough reaction.

[0023] Furthermore, in step (3), the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether to tetramethyldihydrodisiloxane is 1:2-10. This ensures the reaction is complete and thorough.

[0024] Furthermore, in step (4), the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-1-hydrodisiloxyl)]glycidyl ether to propenyl glycidyl ether is 1:2-10 to ensure a complete and sufficient reaction.

[0025] Furthermore, the condensation reaction temperature in step (1) is 50-120℃ and the condensation reaction time is 1-20 hours; the ring-opening reaction temperature in step (2) is 20-120℃ and the ring-opening reaction time is 1-10 hours; the ring-closing reaction temperature is 20-50℃ and the ring-closing reaction time is 1-10 hours; the first addition reaction temperature in step (3) is 50-100℃ and the first addition reaction time is 1-10 hours; the second addition reaction temperature in step (4) is 50-100℃ and the second addition reaction time is 1-10 hours.

[0026] Furthermore, the bismaleimide resin is an oligomeric bismaleimide resin (BMI) with a molecular weight of 500-5000 (structural formula as shown in formula (VI), n = 1-100, n is 10 in the embodiments and comparative examples of this invention), the bisphenol F type epoxy resin is EXA-830CRP from DIC Corporation of Japan, the silane coupling agent is KBM-403 (3-glycidyl ether oxypropyltrimethoxysilane) from Shin-Etsu Chemical Co., Ltd. of Japan, the leveling agent is AC1203 (fatty amine polyoxyethylene ether) from Jiangsu Haian Petrochemical, the black paste is JSLD6909 (carbon black added to bisphenol A epoxy resin) from Jiasheng New Materials, the spherical silica powder is SE6050-SEJ from Yaduma Corporation of Japan, and the curing agent is E-100 (diethyltoluene diamine) from Jiangsu Yarui Chemical Co., Ltd.

[0027]

[0028] The technical effect of adopting the above-mentioned further technical solution is that the maleamide bond in bismaleimide combines with the furan group in tetraglycidyl ether to form a crosslinking point. When the temperature reaches 280℃-300℃ or higher, the crosslinking point of furan group and imide group can undergo reversible decomposition (such as reaction formula 1), which directly affects the interface bonding effect, is conducive to interface delamination, and thus achieves the effect of reworkability.

[0029] Reaction 1:

[0030]

[0031] A second aspect of the present invention is to provide a method for preparing the above-mentioned reworkable chip-level underfill adhesive, comprising the following steps:

[0032] S1. Bisphenol F type epoxy resin and bismaleimide resin are melt-dispersed under vacuum conditions at 100-200℃ to form a premixed resin.

[0033] S2. After mixing and stirring bisphenol F epoxy resin, premixed resin, tetraglycidyl ether containing furan groups, silane coupling agent, and black paste for 1 hour, add spherical silica powder, vacuum heat and stir at 70-90℃ for 2-10 hours, and then perform three-roll milling after cooling to room temperature to form a bottom filler premix.

[0034] S3. Mix the underfill premix, leveling agent, and curing agent together, and stir at 25-30℃ for 1-2 hours to obtain the chip-level underfill.

[0035] The beneficial technical effects of adopting the above technical solution are as follows: bismaleimide resin is a solid powder, and it is convenient to pre-melt-mix it with bisphenol F type epoxy resin for subsequent glue preparation operations.

[0036] Compared with the prior art, the present invention has the following technical effects:

[0037] This invention independently synthesizes a tetraglycidyl ether containing furan groups. This novel compound with a special structure is incorporated into the formulation design along with low molecular weight bismaleimide resin. Through reasonable component ratio design, a reworkable and toughened chip-level underfill adhesive has been successfully developed. This adhesive achieves reworkability within the rework temperature range while also possessing good toughness and high heat resistance, thus improving the reliability testing performance of the chip after packaging. The tetraglycidyl ether containing furan groups provides the chip-level underfill adhesive with high heat resistance and excellent flexibility after curing. The bismaleimide resin combines with the furan groups in the tetraglycidyl ether at high temperatures, reducing the difficulty of reworkability and thus achieving a reworkable effect. Detailed Implementation

[0038] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0039] Synthesis example

[0040] Synthesis process of tetraglycidyl ether containing furan group:

[0041] (1) 328g of 2-methoxy-4-(2-propenyl)phenol, 200g of xylene and 6g of methylimidazolium were added sequentially to a four-necked flask equipped with a stirrer, reflux condenser, thermometer, nitrogen tube and peristaltic pump feed tube. Nitrogen gas was introduced and the temperature was raised to 100℃. 48g of α-furan carboxaldehyde was added dropwise to the four-necked flask over 0.5h using a peristaltic pump. The reaction time was 3h. After the reaction was completed, the temperature was lowered to room temperature (25±3℃). Acetic acid was added to neutralize the mixture to neutral. The neutralized ethanol was distilled off by heating. The mixture in the four-necked flask was filtered and washed three times with distilled water at 100℃. The filter cake was removed and recrystallized three times with toluene. Then it was dried under vacuum at 120℃ for 2h to finally obtain 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol monomer.

[0042] (2) Add 203g of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol and 3.9g of tetrabutylammonium bromide to a four-necked flask equipped with a stirrer, reflux condenser, thermometer, nitrogen gas tube, and peristaltic pump feed tube. Purge with nitrogen and maintain the temperature at 40℃. Control the feed flow rate using the peristaltic pump. Add 185g of epichlorohydrin dropwise to the four-necked flask over 2 hours. React for 2 hours. At this point, the intermediate 6,6'-( Furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]propylchlorohydrin ether was then cooled and controlled at 25°C. 167 g of 48% sodium hydroxide solution was added dropwise to a four-necked flask over 2 hours using a peristaltic pump. The reaction was allowed to proceed for 2 hours. The resulting liquid was filtered, washed, and then excess epichlorohydrin was removed by vacuum distillation to obtain 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether.

[0043] (3) 259g of the above-mentioned 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether was added to a three-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen tube. Nitrogen gas was introduced, 0.5g of platinum catalyst was added, and then 142g of tetramethyldihydrodisiloxane was added. The temperature was raised to 100℃ and the reaction was carried out for 2h to obtain 389g of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethylmonohydrodisiloxane)]glycidyl ether;

[0044] (4) 389g of the above-mentioned 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-1-hydrodisiloxyl)] glycidyl ether was added to a three-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen tube. Nitrogen gas was introduced, 0.5g of platinum catalyst was added, and then 114g of allyl glycidyl ether was added. The temperature was raised to 100℃ and the reaction was carried out for 2h to obtain 501g (TGEF) of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-1-siloxyl)]-tetraglycidyl ether.

[0045] Example 1

[0046] 12g of EXA-830CRP and 1g of bismaleimide resin were first added to a three-necked flask equipped with a stirrer, vacuum tube, and thermometer. The mixture was heated to 155°C and stirred under vacuum until it melted and dispersed until the liquid became clear. Then, 7g of EXA-830CRP, 5g of TGEF, 1g of KBM-403, and 1g of JSLD6909 were added to the three-necked flask, and the mixture was stirred under vacuum at room temperature for 1 hour. Then, 65g of SE6050-SEJ was added, the temperature was raised to 90°C, and the mixture was stirred under vacuum for 4 hours. After cooling to 25°C, the mixture was milled using a three-roll mill.

[0047] 92g of the bottom filler premix that has been milled by three rollers, 1g of AC1203 and 7g of E-100 were added back into a three-necked flask. The mixture was then stirred under vacuum at 25-30°C for 1 hour to obtain the bottom filler of Example 1.

[0048] Example 2

[0049] 12g of EXA-830CRP and 2g of bismaleimide resin were first added to a three-necked flask equipped with a stirrer, vacuum tube, and thermometer. The mixture was heated to 155°C and stirred under vacuum until it melted and dispersed until the liquid became clear. Then, 6g of EXA-830CRP, 5g of TGEF, 1g of KBM-403, and 1g of JSLD6909 were added to the three-necked flask, and the mixture was stirred under vacuum at room temperature for 1 hour. Then, 65g of SE6050-SEJ was added, the temperature was raised to 90°C, and the mixture was stirred under vacuum for 4 hours. After cooling to 25°C, the mixture was milled using a three-roll mill.

[0050] 92g of the bottom filler premix that has been milled by three rollers, 1g of AC1203 and 7g of E-100 were added back into a three-necked flask. The mixture was then stirred under vacuum at 25-30°C for 1 hour to obtain the bottom filler of Example 2.

[0051] Comparative Example 1

[0052] Add 25g of 830CRP, 1g of KBM-403, and 1g of JSLD6909 to a three-necked flask equipped with a stirrer, vacuum tube, and thermometer, and stir under vacuum at room temperature for 1 hour. Then add 65g of SE6050-SEJ, heat to 90°C, and stir under vacuum for 4 hours. After cooling to 25°C, grind the mixture using a three-roll mill.

[0053] 92g of the underfill premix that has been milled by three rollers, 1g of AC1203 and 7g of E-100 were added back into a three-necked flask. The mixture was stirred under vacuum for 1 hour at a controlled temperature of 25-30℃ to obtain the underfill of Comparative Example 1.

[0054] Comparative Example 2

[0055] Add 20g of 830CRP, 5g of MX-125, 1g of KBM-403, and 1g of JSLD6909 to a three-necked flask equipped with a stirrer, vacuum tube, and thermometer, and stir under vacuum at room temperature for 1 hour. Then add 65g of SE6050-SEJ, raise the temperature to 90°C, and stir under vacuum for 4 hours. After cooling to 25°C, grind the mixture using a three-roll mill.

[0056] 92g of the underfill premix that has been milled by three rollers, 1g of AC1203 and 7g of E-100 were added back into a three-necked flask. The mixture was stirred under vacuum for 1 hour at a controlled temperature of 25-30℃ to obtain the underfill of Comparative Example 2.

[0057] Comparative Example 3

[0058] 12g of EXA-830CRP and 1g of bismaleimide resin were first added to a three-necked flask equipped with a stirrer, vacuum tube, and thermometer. The mixture was heated to 155°C and stirred under vacuum until it was melted and dispersed until the liquid was clear. Then, 12g of EXA-830CRP, 1g of KBM-403, and 1g of JSLD6909 were added to the three-necked flask and stirred under vacuum at room temperature for 1 hour. Then, 65g of SE6050-SEJ was added, the temperature was raised to 90°C, and the mixture was stirred under vacuum for 4 hours. After cooling to 25°C, the mixture was milled using a three-roll mill.

[0059] 92g of the underfill premix that has been milled by three rollers, 1g of AC1203 and 7g of E-100 were added back into a three-necked flask. The mixture was stirred under vacuum for 1 hour while maintaining the temperature at 25-30℃ to obtain the underfill of Comparative Example 3.

[0060] Comparative Example 4

[0061] Add 22g of EXA-830CRP, 3g of TGEF, 1g of KBM-403, and 1g of JSLD6909 to a three-necked flask equipped with a stirrer, vacuum tube, and thermometer, and stir under vacuum at room temperature for 1 hour. Then add 65g of SE6050-SEJ, raise the temperature to 90°C, and stir under vacuum for 4 hours. After cooling to 25°C, grind the mixture using a three-roll mill.

[0062] 92g of the underfill premix that has been milled by three rollers, 1g of AC1203 and 7g of E-100 were added back into a three-necked flask. The mixture was stirred under vacuum for 1 hour while maintaining the temperature at 25-30℃ to obtain the underfill of Comparative Example 4.

[0063] Comparative Example 5

[0064] Add 20g of EXA-830CRP, 5g of TGEF, 1g of KBM-403, and 1g of JSLD6909 to a three-necked flask equipped with a stirrer, vacuum tube, and thermometer, and stir under vacuum at room temperature for 1 hour. Then add 65g of SE6050-SEJ, heat to 90℃, and stir under vacuum for 4 hours. After cooling to 25℃, grind the mixture using a three-roll mill.

[0065] 92g of the underfill premix that has been milled by three rollers, 1g of AC1203 and 7g of E-100 were added back into a three-necked flask. The mixture was stirred under vacuum for 1 hour while maintaining the temperature at 25-30℃ to obtain the underfill of Comparative Example 5.

[0066] The formulations of each embodiment and comparative example are shown in Table 1.

[0067] Table 1. Formulations (parts by weight) of the Examples and Comparative Examples

[0068]

[0069]

[0070] test

[0071] Silicon surface adhesion test: Using a custom mold, the underfill adhesive was cured onto the silicon wafer surface in a pudding shape. Then, using a DAGE 4000 tester with the platform temperature set at 260°C, the pudding-shaped adhesive block was pushed off the silicon wafer surface. The force at the moment of detachment is the adhesion force of the underfill adhesive to the silicon surface. Table 2 lists the silicon surface adhesion force data for the examples and comparative examples.

[0072] Other tests: The Tg (DMA) and storage modulus of the cured material were measured using ASTM D7028; the coefficients of thermal expansion (CTE1 and CTE2) of the cured material were measured using GB / T 36800.2-2018; and the flexural strength and flexural modulus of the cured material were measured using GB / T 9341-2008. Table 2 lists other test data for the examples and comparative examples.

[0073] Table 2 Comparison of key performance characteristics of the embodiments and comparative examples.

[0074]

[0075]

[0076] As shown in Table 2, Comparative Example 1 is the most basic chip-level underfill adhesive formulation, and Comparative Example 2 is a traditional core-shell toughening treatment performed on the basic formulation. It can be seen from the fact that the high temperature modulus is reduced and K1C is increased compared with Comparative Example 1.

[0077] Comparative Example 3 only added low molecular weight bismaleimide resin (BMI). Compared with Comparative Examples 1 and 2, the modulus was slightly increased, the adhesion attenuation rate at 260℃ after uHast was reduced, the adhesion attenuation rate at 260℃ after HTST for 1000h was reduced, and the K1C toughness parameter and the elongation at break toughness parameter at 245℃ were reduced. These are all related to the introduction of rigid groups by the maleamide bonds contained in BMI.

[0078] Compared with Comparative Examples 1 and 2, Comparative Examples 4 and 5, with the addition of 3% and 5% of self-synthesized TGEF respectively, showed a slight decrease in modulus, a decrease in the adhesion attenuation rate at 260℃ after Hast treatment, a decrease in the adhesion attenuation rate at 260℃ after 1000h of HTST treatment, and an increase in K1C toughness parameter and elongation at break toughness parameter at 245℃. These are all related to the introduction of polyfunctional epoxy groups, siloxane flexible segments, furan groups, and phenyl groups into the self-synthesized TGEF containing maleamide bonds.

[0079] In Examples 1 and 5, both self-synthesized TGEF and low molecular weight BMI were added. Compared with Comparative Examples 1 and 2, the modulus at 300℃ was significantly reduced, and the adhesive strength at 300℃ was significantly weakened. These two points are related to the reversible decomposition of furan groups in the self-synthesized TGEF and maleamide bonds in the BMI at high temperatures (300℃), as well as the siloxane flexible segments and polyether bonds in the self-synthesized TGEF. Furthermore, the adhesive strength attenuation rates at 260℃ after uHast and after 1000h of HTST were still at relatively low levels. This is related to the furan groups and phenyl groups in the TGEF, and the maleamide bonds in the BMI. It also indicates that although the furan groups in the self-synthesized TGEF and the maleamide bonds in the BMI undergo reversible decomposition at high temperatures (300℃), they are not affected by the temperatures commonly used in semiconductor packaging reliability testing, such as UHast and HTST (130℃ and 150℃, respectively). Furthermore, the K1C toughness parameter and the elongation at break toughness parameter at 245℃ were increased, which is related to the siloxane flexible segments and polyether bonds in the self-synthesized TGEF.

[0080] Comparing Examples 1 and 2, when the low molecular weight BMI content is 2%, although the adhesion attenuation rate at 260°C after uHast and the adhesion attenuation rate at 260°C after 1000h HTST are further reduced, the K1C toughness parameter and the elongation at break toughness parameter at 245°C are slightly reduced, and the viscosity is increased. Therefore, considering all the above performance aspects, the formulation represented by Example 2 is the best performing formulation in this patent.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A reworkable, toughened chip-level underfill adhesive, characterized in that, By weight, it contains the following components: 15-25 parts of bisphenol F type epoxy resin, 3-8 parts of tetraglycidyl ether containing furan groups, 0.5-2 parts of bismaleimide resin, 0.5-1.5 parts of silane coupling agent, 0.5-1.5 parts of leveling agent, 0.5-1.5 parts of black paste, 60-70 parts of spherical silica powder, and 5-15 parts of curing agent; The furan-containing tetraglycidyl ether is 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyldisiloxyl)]-tetraglycidyl ether, with the structural formula shown below. 。 2. The reworkable toughened chip-level underfill adhesive according to claim 1, characterized in that, The furan-containing tetraglycidyl ether was prepared by the following method: (1) Using α-furanaldehyde and 2-methoxy-4-(2-propenyl)phenol as the monomers in the first step reaction, xylene as the solvent and methylimidazolium as the catalyst, 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol was obtained by condensation reaction. (2) Using 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol and epichlorohydrin as monomers in the second step reaction, and tetrabutylammonium bromide as a phase transfer catalyst, the ring-opening reaction yields the intermediate 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]propylchlorohydrin ether. Sodium hydroxide is then added, and the ring-closing reaction yields 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether. (3) Using 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether and tetramethyldihydrodisiloxane as the monomers for the third step reaction, a platinum catalyst was added, and 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyldihydrodisiloxane)]glycidyl ether was obtained by the first addition reaction; (4) Using 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-1-hydrodisiloxyl)] glycidyl ether and propenyl glycidyl ether as monomers in the fourth step reaction, a platinum catalyst was added, and 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-1-hydrodisiloxyl)]-tetraglycidyl ether was obtained through a second addition reaction.

3. The reworkable toughened chip-level underfill adhesive according to claim 2, characterized in that, In step (1), the molar ratio of α-furan carboxaldehyde to 2-methoxy-4-(2-propenyl)phenol is 1:1-1:5, the mass ratio of methylimidazolium to the monomer of the first step reaction is 0.1-10:100, and the mass ratio of xylene to the monomer of the first step reaction is 40-80:

100.

4. The reworkable toughened chip-level underfill adhesive according to claim 2, characterized in that, In step (2), the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]phenol to epichlorohydrin is 1:2-20, the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]propylchlorohydrin ether to sodium hydroxide is 1:2-10, and the mass ratio of tetrabutylammonium bromide to the monomer of the second step reaction is 0.1-2:

100.

5. The reworkable toughened chip-level underfill adhesive according to claim 2, characterized in that, In step (3), the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-allyl)]-diglycidyl ether to tetramethyldihydrodisiloxane is 1:2-10.

6. The reworkable toughened chip-level underfill adhesive according to claim 2, characterized in that, In step (4), the molar ratio of 6,6'-(furan-2-methylene)-bis[(2-methoxy)-(4-tetramethyl-1-hydrodisiloxyl)]glycidyl ether to propylene glycidyl ether is 1:2-10.

7. The reworkable toughened chip-level underfill adhesive according to claim 2, characterized in that, The condensation reaction temperature in step (1) is 50-120℃ and the condensation reaction time is 1-20 hours; the ring-opening reaction temperature in step (2) is 20-120℃ and the ring-opening reaction time is 1-10 hours; the ring-closing reaction temperature is 20-50℃ and the ring-closing reaction time is 1-10 hours; the first addition reaction temperature in step (3) is 50-100℃ and the first addition reaction time is 1-10 hours; the second addition reaction temperature in step (4) is 50-100℃ and the second addition reaction time is 1-10 hours.

8. The reworkable toughened chip-level underfill adhesive according to claim 1, characterized in that, The molecular weight of the bismaleimide resin is 500-5000, the bisphenol F epoxy resin is EXA-830CRP from DIC Corporation of Japan, the silane coupling agent is KBM-403 from Shin-Etsu Chemical Co., Ltd. of Japan, the leveling agent is AC1203 from Jiangsu Haian Petrochemical, the black paste is JSLD6909 from Jiasheng New Materials, the spherical silica powder is SE6050-SEJ from Yaduma Corporation of Japan, and the curing agent is E-100 from Jiangsu Yarui Chemical Co., Ltd.

9. A method for preparing a reworkable toughened chip-level underfill adhesive according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Bisphenol F type epoxy resin and bismaleimide resin are melt-dispersed under vacuum conditions at 100-200℃ to form a premixed resin. S2. After mixing and stirring bisphenol F epoxy resin, premixed resin, tetraglycidyl ether containing furan groups, silane coupling agent, and black paste for 1 hour, add spherical silica powder, vacuum heat and stir at 70-90℃ for 2-10 hours, and then perform three-roll milling after cooling to room temperature to form a bottom filler premix. S3. Mix the underfill premix, leveling agent, and curing agent together, and stir at 25-30℃ for 1-2 hours to obtain the underfill.

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