Highly thermally conductive adhesive for electronic encapsulation and method for preparing the same

Abstract

The present application relates to the technical field of adhesive, and particularly relates to a high-thermal-conductivity adhesive for electronic packaging and a preparation method thereof.The high-thermal-conductivity adhesive for electronic packaging comprises, by weight fraction, 55-60 parts of acrylate monomer, 40-45 parts of methacrylate monomer, 0.5-5 parts of photoinitiator, 10-25 parts of modified boron nitride, 1-3 parts of thixotropic agent, 0.2-1 part of defoaming agent and 0.5-1 part of antioxidant.The present application introduces the methacrylate monomer with a novel structure into the adhesive, endows the adhesive with excellent hydrolysis resistance, effectively reduces the volume shrinkage rate of the adhesive, and improves the thermal conductivity of the adhesive.In addition, the modified boron nitride introduced into the adhesive can avoid the agglomeration of boron nitride, improve the dispersibility and compatibility of the boron nitride, and further improve the thermal conductivity of the adhesive.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesives, in particular to a high-thermal-conductivity adhesive for electronic packaging and a preparation method thereof. BACKGROUND

[0002] In the current UV / EB curing field, HDDA (1,6-hexanediol diacrylate) and TPGDA (tripropylene glycol diacrylate) are the most commonly used base monomers in industrial formulations. Although these two short-chain difunctional monomers have high reactivity and low price, they also have obvious defects: the glass transition temperature of their cured films is usually higher than 30℃, and brittle fracture easily occurs in low-temperature bending scenarios; the high double bond density leads to a volume shrinkage rate of 6-10%, which easily causes internal stress, warping, and even cracking; and in order to reduce the Tg or shrinkage rate, plasticizers or high molecular diluents are often mixed in, but this brings problems such as increased VOC, decreased curing rate, and even fluctuating physical properties.

[0003] In order to solve the above problems, domestic and foreign research has attempted to use long-chain dimer fatty aliphatic raw materials for modification, but related Chinese patents are mostly limited to the application of "dimer acid" or its polyester, polyurethane derivatives: CN101544721A uses dimer acid to prepare a water-resistant acrylic emulsion, which improves flexibility, but the emulsion formulation contains a large number of ester bonds and emulsifiers, and the final product has problems such as deep color, high acid value, and limited hydrolytic stability; CN118146478A uses isocyanate to further cap the dimer acid polyester to obtain a polyurethane acrylate, which faces the risks of yellowing and hydrolysis after wet heat aging due to the presence of urea / urethane bonds. Therefore, it is necessary to develop a flexible-hydrophobic active monomer.

[0004] In addition, improving the thermal conductivity of adhesives is crucial in the field of electronic packaging, and high thermal conductivity helps to dissipate heat from the device and improve reliability, which has become one of the important directions for the development of high-performance adhesives. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, one of the purposes of the present application is to provide a high-thermal-conductivity adhesive for electronic packaging, which introduces a synthetic methacrylate monomer with a novel structure and modified boron nitride into the adhesive formulation, giving the adhesive excellent hydrolysis resistance, effectively reducing its volume shrinkage rate, and significantly improving the thermal conductivity of the adhesive.

[0006] The second purpose of the present application is to provide a preparation method for a high-thermal-conductivity adhesive for electronic packaging, which is simple and easy to implement and has important significance in industrial production applications.

[0007] One of the purposes of the present application is achieved by the following technical solutions:

[0008] The high-thermal-conductivity adhesive for electronic packaging comprises, in parts by weight, 55-60 parts of acrylate monomer, 40-45 parts of methacrylate monomer, 0.5-5 parts of photoinitiator, 10-25 parts of modified boron nitride, 1-3 parts of thixotropic agent, 0.2-1 part of defoaming agent, and 0.5-1 part of antioxidant.

[0009] The modified boron nitride is prepared as follows:

[0010] The boron nitride is dispersed in a sodium hydroxide solution, treated under nitrogen protection, washed and dried to obtain hydroxyl boron nitride, which is then dispersed in a solvent, and 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one and a sodium hydroxide solution are added for heating reaction.

[0011] Further, the boron nitride and the sodium hydroxide solution are used in a ratio of 1-3 g:15-30 mL; the 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one, hydroxyl boron nitride, solvent and sodium hydroxide solution are used in a ratio of 1 g:3.0-3.2 g:30-35 mL:0.6-0.8 mL, and the solvent is acetone; and the sodium hydroxide solution has a concentration of 5 mol / L.

[0012] Further, the treatment is performed at a temperature of 90-100℃ for 11-12 h; and the heating reaction is performed at a temperature of 70-75℃ for 4-6 h.

[0013] Further, the methacrylate monomer is prepared as follows:

[0014] (1) Under nitrogen protection, 4-(bromomethyl)phenylboronic acid, 5-furfuryl-2-boronic acid, K2CO3 and PdCl2 are added to a DMF aqueous solution for heating reaction, and after the reaction is completed, the reaction liquid is extracted, washed and recrystallized to obtain intermediate 1.

[0015] (2) Under nitrogen protection, 7-bromo-1-heptanol, intermediate 1, K2CO3 and PdCl2 are added to a DMF aqueous solution for heating reaction, and after the reaction is completed, the reaction liquid is extracted, washed and recrystallized to obtain intermediate 2.

[0016] (3) Intermediate 2, methacrylic acid, p-toluenesulfonic acid and dibutylhydroxytoluene are added to a DMF toluene solution for reaction, the reaction liquid is cooled and adjusted to neutral pH, and then distilled, washed and dried to obtain the methacrylate monomer.

[0017] Further, in step (1), the 4-(bromomethyl)benzene boronic acid, 5-furfuryl alcohol-2-boronic acid, K2CO3, PdCl2, DMF aqueous solution are used in a ratio of 5mmol:5-5.5mmol:5.5-6.5mmol:0.5-2mmol:10-15mL; the DMF aqueous solution is obtained by mixing DMF and deionized water in a volume ratio of 10:(0.5-1); the heating reaction temperature is 45-50℃, and the time is 18-24h.

[0018] Further, in step (2), the 7-bromo-1-heptanol, intermediate 1, K2CO3, PdCl2, DMF aqueous solution are used in a ratio of 5mmol:5-5.5mmol:5.5-6.5mmol:0.5-2mmol:12-15mL; the DMF aqueous solution is obtained by mixing DMF and deionized water in a volume ratio of 10:(0.5-1); the heating reaction temperature is 45-50℃, and the time is 18-24h.

[0019] Further, in step (3), the intermediate 2, methacrylic acid, p-toluenesulfonic acid, dibutyl hydroxytoluene and DMF toluene solution are used in a ratio of 5g:1.8-2g:0.03-0.08g:0.003-0.03g:10-15mL; the DMF toluene solution is obtained by mixing DMF and toluene in a volume ratio of 1:(1-2); the reaction temperature is 90-120℃, and the time is 4-8h.

[0020] Further, the acrylate monomer is tripropyleneglycol diacrylate or 1,6-hexanediol diacrylate; the photoinitiator is benzoin dimethyl ether; the thixotropic agent is fumed silica; the defoaming agent is defoaming agent BYK-1790; and the antioxidant is at least one of antioxidant 1010, antioxidant 1072 or antioxidant 1024.

[0021] The second object of the application is achieved by the following technical scheme:

[0022] The preparation method of the high-thermal-conductivity electronic packaging adhesive comprises the following steps: uniformly mixing acrylate monomers, methacrylate monomers, modified boron nitride, thixotropic agents, defoaming agents and antioxidants, then adding a photoinitiator, vacuumizing to-0.1~-0.08MPa, pressure-maintaining stirring for 3-5h, vacuum defoaming and discharging, and the high-thermal-conductivity electronic packaging adhesive is obtained.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] 1. In view of the pain point of short-chain diacrylate "high Tg + high shrinkage + poor hydrolysis resistance", the present application synthesizes a hydrophobic diol containing a flexible alkyl chain and a benzene ring structure through Suzuki coupling reaction, and then prepares a methacrylate monomer through esterification reaction. The amorphous long-chain aliphatic hydrocarbon skeleton structure in the monomer is flexible and hydrophobic, which can give the adhesive very low glass transition temperature (Tg), excellent hydrolysis resistance, and effectively reduce the volume shrinkage. In addition, the introduction of rigid conjugated benzene ring in the structure helps to promote phonon transmission, which has a positive effect on improving the thermal conductivity of the adhesive.

[0025] 2. The present application also introduces modified boron nitride to improve the thermal conductivity of the adhesive. Boron nitride itself serves as a high thermal conductivity skeleton, while the organic molecules grafted through the reaction of 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one and hydroxyl boron nitride effectively optimize the interfacial heat transfer performance. The trifluoromethyl sulfonyl (-SO2CF3) and carbonyl (C=O) introduced in the modified boron nitride have strong polarity, which can form hydrogen bonds or dipole interactions with the acrylate matrix. This not only helps to reduce the agglomeration of modified boron nitride, improve its dispersibility and compatibility, thereby reducing the thermal resistance of the polymer-filler interface; at the same time, the strong electronegativity of trifluoromethyl sulfonyl can also induce the local polarization of the acrylate molecular chain, promote the formation of more ordered microstructure, and reduce the interference of disordered thermal vibration on phonon transmission. In addition, the aromatic structure of indenone can produce π-π stacking effect with the benzene ring in the methacrylate monomer, further enhancing the coupling and transmission efficiency of phonons at the interface. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Infrared contrast spectrum of modified boron nitride and boron nitride obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings and specific embodiments. It should be noted that the following described embodiments or technical features can be combined in any manner to form new embodiments without conflict. The specific conditions in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, such as those not specifically mentioned, are conventional products obtained through commercial channels.

[0028] Example 1

[0029] A high-thermal-conductivity electronic packaging adhesive comprises, by weight fraction, 58 parts of an acrylate monomer (tripropylene glycol diacrylate), 42 parts of a methacrylate monomer, 3 parts of a photoinitiator (benzoin dimethyl ether), 20 parts of modified boron nitride, 2 parts of a thixotropic agent (fumed silica), 0.6 part of an antifoaming agent (antifoaming agent BYK-1790), and 0.8 part of an antioxidant (antioxidant 1010).

[0030] The modified boron nitride is prepared as follows:

[0031]

[0032] The boron nitride powder is dispersed in a 5-mol / L sodium hydroxide solution, and the use amount ratio of the boron nitride powder to the sodium hydroxide solution is 2 g:25 mL; after treatment at 95℃ for 12 h under nitrogen protection, the hydroxyl boron nitride is obtained through washing and drying, and then the hydroxyl boron nitride is dispersed in acetone, 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one is added, and after dissolution, a 5-mol / L sodium hydroxide solution is added; the use amount ratio of 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one, the hydroxyl boron nitride, acetone, and the sodium hydroxide solution is 1 g:3.1 g:33 mL:0.7 mL; after reaction at 72℃ for 5 h, the pH of the reaction solution is adjusted to neutral, and the modified boron nitride is obtained through filtration, acetone washing, and vacuum drying.

[0033] The infrared spectrum of the modified boron nitride is shown in Figure 1 As shown in Figure 1 , the modified boron nitride has characteristic absorption peaks of C=O, S=O, and C-F at 1725 cm -1 , 1205 cm -1 , and 1065 cm -1 , indicating that the boron nitride is successfully modified.

[0034] The methacrylate monomer is prepared as follows:

[0035]

[0036] (1) Under nitrogen protection, 4-(bromomethyl)phenylboronic acid, 5-furfuryl alcohol-2-boronic acid, K2CO3, and PdCl2 are added to a DMF aqueous solution (V DMF :V 去离子水=10:1), the amount ratio of 4-(bromomethyl)phenylboronic acid, 5-furfuryl-2-boronic acid, K2CO3, PdCl2, DMF aqueous solution was 5 mmol: 5.2 mmol: 6 mmol: 1.3 mmol: 13 mL; after the reaction at 48°C for 20 h, the reaction solution was extracted with deionized water and ethyl acetate, the obtained organic phase was washed with deionized water, recrystallized with n-hexane / ethyl acetate to obtain the intermediate 1 (yield 73.4%);

[0037] Preparation of the intermediate 1 1 HNMR: (CDC13, 400 MHz, DMSO-d6) δ: 0.86-0.95 (m, 6H), 1.17-1.33 (m, 6H), 1.38-1.42 (m, 4H), 1.86-1.90 (m, H), 2.33-2.37 (m, H), 2.58-2.62 (m, H), 3.38-3.42 (m, H), 4.2 (s, 2H), 4.8 (s, H), 7.19-7.21 (d, 2H), 7.74-7.76 (d, 2H). MS (ESI) m / z = 278.21 [M]. 16 H 27 BO3, 400 MHz, DMSO-d6) δ: 0.86-0.95 (m, 6H), 1.17-1.33 (m, 6H), 1.38-1.42 (m, 4H), 1.86-1.90 (m, H), 2.33-2.37 (m, H), 2.58-2.62 (m, H), 3.38-3.42 (m, H), 4.2 (s, 2H), 4.8 (s, H), 7.19-7.21 (d, 2H), 7.74-7.76 (d, 2H). MS (ESI) m / z = 278.21 [M].

[0038] (2) Under the protection of nitrogen, 7-bromo-1-heptanol, the intermediate 1, K2CO3 and PdCl2 were added into DMF aqueous solution (V DMF :V 去离子水 =10:1), the amount ratio of 4-(bromomethyl)phenylboronic acid, 5-furfuryl-2-boronic acid, K2CO3, PdCl2, DMF aqueous solution was 5 mmol: 5.2 mmol: 6 mmol: 1.3 mmol: 13 mL; after the reaction at 48°C for 20 h, the reaction solution was extracted with deionized water and ethyl acetate, the obtained organic phase was washed with deionized water, recrystallized with n-hexane / ethyl acetate to obtain the intermediate 1 (yield 73.4%); 1 HNMR: (CDC13, 400 MHz, DMSO-d6) δ: 0.86-0.95 (m, 6H), 1.17-1.33 (m, 6H), 1.38-1.42 (m, 4H), 1.86-1.90 (m, H), 2.33-2.37 (m, H), 2.58-2.62 (m, H), 3.38-3.42 (m, H), 4.2 (s, 2H), 4.8 (s, H), 7.19-7.21 (d, 2H), 7.74-7.76 (d, 2H). MS (ESI) m / z = 278.21 [M]. 23 H 40 O2, 400 MHz, DMSO- d6 )δ:0.86-0.95(m,6H),1.17-1.34(m,10H),1.38-1.45(m,6H),1.56-1.65(m,4H),1.86-1.90(m,H),2.33-2.37(m,H),2.57-2.62(m,3H),3.38-3.42(m,H),3.60-3.64(t,2H),4.7(s,H),4.8(s,H),7.05(m,4H)。MS (ESI) m / z=348.30[M]。

[0039] (3) Intermediate 2, methacrylic acid, p-toluenesulfonic acid and polymerization inhibitor dibutylhydroxytoluene (BHT) were added into a toluene solution of DMF (v / v, 1:1), and the amount ratio of intermediate 2, methacrylic acid, p-toluenesulfonic acid, dibutylhydroxytoluene and the toluene solution of DMF was 5 g:1.9 g:0.05 g:0.02 g:13 mL; after reaction at 110°C for 6 h, the reaction solution was cooled to 70°C, 10 wt% aqueous sodium bicarbonate solution was added to adjust the pH of the solution to neutral, the solvent and water were removed by distillation under reduced pressure, washed with deionized water and vacuum dried to obtain the methacrylate monomer (yield 78.9%). The methacrylate monomer was analyzed by HPLC and the purity was 99.5%. 1 HNMR: (C 31 H 48 O4, 400 MHz, DMSO- d6 ) δ: 0.86-0.95 (m, 6H), 1.17-1.34 (m, 10H), 1.41-1.51 (m, 6H), 1.58-1.65 (m, 4H), 1.86-1.90 (m, H), 2.01 (s, 6H), 2.33-2.37 (m, H), 2.57-2.62 (m, 3H), 3.95-3.99 (t, 2H), 4.45-4.50 (m, H), 6.39-6.41 (m, 2H), 6.47-6.49 (m, 2H), 7.05 (m, 4H). MS (ESI) m / z = 484.36 [M].

[0040] The embodiment also provides a preparation method of the high-thermal-conductivity electronic packaging adhesive described above, which comprises the following steps: sequentially adding the acrylate monomer, the methacrylate monomer, the modified boron nitride, the thixotropic agent, the defoaming agent and the antioxidant into a double-planet stirring kettle and uniformly mixing, then adding the photoinitiator, vacuumizing to-0.1 MPa, pressure-maintaining stirring for 4 h, vacuum defoaming and discharging, so that the high-thermal-conductivity electronic packaging adhesive is obtained.

[0041] Example 2

[0042] A high-thermal-conductivity electronic packaging adhesive comprises, by weight fraction, 55 parts of acrylate monomer (di-tripropylene glycol diacrylate), 40 parts of methacrylate monomer, 1 part of photoinitiator (benzoin dimethyl ether), 10 parts of modified boron nitride, 1 part of thixotropic agent (fumed silicon dioxide), 0.2 part of defoaming agent (defoaming agent BYK-1790) and 0.5 part of antioxidant (antioxidant 1072).

[0043] The preparation process of the modified boron nitride is as follows:

[0044] The boron nitride powder is dispersed in a sodium hydroxide solution with a concentration of 5 mol / L, the use amount ratio of the boron nitride powder and the sodium hydroxide solution is 1 g:15 mL; after being treated at 90°C for 11 hours under nitrogen protection, the hydroxyl boron nitride is obtained through washing and drying, then the hydroxyl boron nitride is dispersed in acetone, 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one is added, after being dissolved, a sodium hydroxide solution with a concentration of 5 mol / L is added, the use amount ratio of 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one, hydroxyl boron nitride, acetone and the sodium hydroxide solution is 1 g:3.0 g:30 mL:0.6 mL; after being reacted at 70°C for 6 hours, the pH of the reaction solution is adjusted to neutral, and then the modified boron nitride is obtained through filtering, acetone washing and vacuum drying.

[0045] The preparation process of the methacrylate monomer is as follows:

[0046] (1) Under nitrogen protection, 4-(bromomethyl)phenylboronic acid, 5-furfuryl-2-boronic acid, K2CO3 and PdCl2 are added into a DMF aqueous solution (V DMF :V 去离子水 =10:1), the use amount ratio of 4-(bromomethyl)phenylboronic acid, 5-furfuryl-2-boronic acid, K2CO3, PdCl2 and the DMF aqueous solution is 5 mmol:5 mmol:5.5 mmol:0.5 mmol:10 mL; after being reacted at 45°C for 24 hours, the reaction solution is extracted with deionized water and ethyl acetate, the obtained organic phase is washed with deionized water, and recrystallized with n-hexane / ethyl acetate to obtain the intermediate 1 (the yield is 71.6%); the intermediate 1 is characterized by HNMR and MS (ESI) m / z, and the characterization results are the same as those in Example 1. 1

[0047] (2) Under nitrogen protection, 7-bromo-1-heptanol, the intermediate 1, K2CO3 and PdCl2 are added into a DMF aqueous solution (V DMF :V 去离子水 =10:1), the use amount ratio of the 7-bromo-1-heptanol, the intermediate 1, K2CO3, PdCl2 and the DMF aqueous solution is 5 mmol:5 mmol:5.5 mmol:0.5 mmol:12 mL; after being reacted at 45°C for 24 hours, the reaction solution is extracted with deionized water and ethyl acetate, the obtained organic phase is washed with deionized water, and recrystallized with n-hexane / ethyl acetate to obtain the intermediate 2 (the yield is 70.2%); the intermediate 2 is characterized by HNMR and MS (ESI) m / z, and the characterization results are the same as those in Example 1. 1

[0048] ​​(3) Intermediate 2, methacrylic acid, p-toluenesulfonic acid and polymerization inhibitor BHT were added into a toluene solution of DMF (v / v, 1:1), and the amount ratio of Intermediate 2, methacrylic acid, p-toluenesulfonic acid, dibutyl hydroxytoluene and the toluene solution of DMF was 5 g:1.8 g:0.03 g:0.003 g:10 mL; after reaction at 90°C for 8 h, the reaction solution was cooled to 60°C, 10 wt% aqueous sodium bicarbonate solution was added to adjust the pH of the solution to neutral, the solvent and water were removed by distillation under reduced pressure, washed with deionized water and vacuum dried to obtain the methacrylate monomer (yield 76.5%). The methacrylate monomer was characterized by HNMR and MS (ESI) m / z. 1 HNMR and MS (ESI) m / z characterization results were the same as those of Example 1.

[0049] The present embodiment also provides a preparation method of the adhesive for high-thermal-conductivity electronic packaging, which comprises the following steps: sequentially adding an acrylate monomer, a methacrylate monomer, modified boron nitride, a thixotropic agent, a defoaming agent and an antioxidant into a double-planet stirring kettle to mix uniformly, then adding a photoinitiator, vacuumizing to-0.08 MPa, pressure-maintaining stirring for 3 h, vacuum defoaming and discharging to obtain the adhesive for high-thermal-conductivity electronic packaging.

[0050] Example 3

[0051] An adhesive for high-thermal-conductivity electronic packaging, which comprises, by weight fraction, 60 parts of an acrylate monomer (1,6-hexanediol diacrylate), 45 parts of a methacrylate monomer, 5 parts of a photoinitiator (benzpinacol), 25 parts of modified boron nitride, 3 parts of a thixotropic agent (fumed silica), 1 part of a defoaming agent (defoaming agent BYK-1790) and 1 part of an antioxidant (antioxidant 1024).

[0052] The preparation process of the modified boron nitride is as follows:

[0053] The boron nitride powder was dispersed in a sodium hydroxide solution with a concentration of 5 mol / L, and the amount ratio of the boron nitride powder and the sodium hydroxide solution was 3 g:30 mL; after treatment at 100°C for 11 h under nitrogen protection, the hydroxyl boron nitride was obtained by washing and drying, then the hydroxyl boron nitride was dispersed in acetone, 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one was added, after dissolution, a sodium hydroxide solution with a concentration of 5 mol / L was added, and the amount ratio of 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one, hydroxyl boron nitride, acetone and the sodium hydroxide solution was 1 g:3.2 g:35 mL:0.8 mL; after reaction at 75°C for 4 h, the pH of the reaction solution was adjusted to neutral, and the modified boron nitride was obtained by filtration, acetone washing and vacuum drying.

[0054] The preparation process of the methacrylate monomer is as follows:

[0055] (1) Under nitrogen protection, 4-(bromomethyl) phenylboronic acid, 5-furfuryl alcohol-2-boronic acid, K2CO3 and PdCl2 were added into DMF aqueous solution (V DMF :V 去离子水 =10:1), and the amount ratio of 4-(bromomethyl) phenylboronic acid, 5-furfuryl alcohol-2-boronic acid, K2CO3, PdCl2 and DMF aqueous solution was 5 mmol:5.5 mmol:6.5 mmol:2 mmol:15 mL; after reaction at 50°C for 24 h, the reaction solution was extracted with deionized water and ethyl acetate, the obtained organic phase was washed with deionized water, recrystallized with n-hexane / ethyl acetate to obtain intermediate 1 (yield 72.8%); the intermediate 1 was characterized by HNMR and MS (ESI) m / z, and the characterization results were the same as those of Example 1. 1

[0056] (2) Under nitrogen protection, 7-bromo-1-heptanol, intermediate 1, K2CO3 and PdCl2 were added into DMF aqueous solution (V DMF :V 去离子水 =10:1), and the amount ratio of 7-bromo-1-heptanol, intermediate 1, K2CO3, PdCl2 and DMF aqueous solution was 5 mmol:5.5 mmol:6.5 mmol:2 mmol:15 mL; after reaction at 50°C for 18 h, the reaction solution was extracted with deionized water and ethyl acetate, the obtained organic phase was washed with deionized water, recrystallized with n-hexane / ethyl acetate to obtain intermediate 2 (yield 71.4%); the intermediate 2 was characterized by HNMR and MS (ESI) m / z, and the characterization results were the same as those of Example 1. 1

[0057] (3) Intermediate 2, methacrylic acid, p-toluenesulfonic acid and polymerization inhibitor BHT were added into DMF toluene solution (v / v, 1:1), and the amount ratio of intermediate 2, methacrylic acid, p-toluenesulfonic acid, dibutylhydroxytoluene and DMF toluene solution was 5 g:2 g:0.08 g:0.03 g:15 mL; after reaction at 120°C for 4 h, the reaction solution was cooled to 80°C, 10 wt% sodium bicarbonate aqueous solution was added to adjust the pH of the solution to neutral, the solvent and water were removed by reduced pressure distillation, washed with deionized water and vacuum dried to obtain the methacrylate monomer (yield 78.1%). The methacrylate monomer was characterized by HNMR and MS (ESI) m / z, and the characterization results were the same as those of Example 1. 1

[0058] ​​​The embodiment also provides a preparation method of the adhesive for high-thermal-conductivity electronic packaging, comprising the following steps: sequentially adding an acrylate monomer, a methacrylate monomer, modified boron nitride, a thixotropic agent, a defoaming agent and an antioxidant into a double-planet stirring kettle and uniformly mixing, then adding a photoinitiator, vacuumizing to-0.1 MPa, pressure-maintaining stirring for 5 hours, vacuum defoaming and discharging, and thus the adhesive for high-thermal-conductivity electronic packaging is obtained.

[0059] Comparative Example 1

[0060] The difference between the present comparative example 1 and example 1 lies in that the modified boron nitride is replaced by boron nitride, and the other conditions are consistent with those in example 1.

[0061] Comparative Example 2

[0062] The difference between the present comparative example 2 and example 1 lies in that the methacrylate monomer is replaced by tripropyleneglycol diacrylate, and the other conditions are consistent with those in example 1.

[0063] Test Example

[0064] (1) Shear strength: the adhesive obtained in examples 1-3 and comparative examples 1-2 is cured between glass and glass, the curing condition is: irradiation under a 80-w ultraviolet lamp with a wavelength of 340 nm for 120 s, the thickness of the adhesive film is 0.15 mm. The shear strength is tested according to the standard of GB / T7124-2008.

[0065] (2) Hydrolysis resistance: the adhesive obtained in examples 1-3 and comparative examples 1-2 is cured between glass and glass (the curing condition is the same as above), and then is stored in a high-temperature and high-humidity condition of 85 DEG C and 95% relative humidity for 1000 h, the shear strength is tested according to the standard of GB / T7124-2008, and the shear strength after the high-temperature and high-humidity treatment is used to evaluate the hydrolysis resistance of the adhesive.

[0066] (3) Volume shrinkage rate: the volume shrinkage rate of the adhesive is tested according to the test standard of ISO3521:1997.

[0067] (4) Water absorption rate: the adhesive is cured between glass and glass (the curing condition is the same as above), and then is soaked in deionized water at 25 DEG C for 72 h, and the water absorption rate of the adhesive film is calculated.

[0068] (5) Thermal conductivity: the thermal conductivity is detected according to the test standard of GB / T10297-2015.

[0069] (6) Differential scanning calorimeter was used to determine the glass transition temperature (Tg). The samples of Examples 1-3 and Comparative Examples 1 and 2 were balanced at -80℃ and kept at this temperature for 2 min, and then heated to melt at a rate of 10℃ / min. The peak temperature of the sample from the glass state to the liquid state was recorded, that is, the glass transition temperature Tg.

[0070] Table 1

[0071]

[0072] From the test results of Table 1, it can be seen that the adhesive obtained by Examples 1-3 has good shear strength, excellent hydrolysis resistance, and can effectively reduce the volume shrinkage rate, thereby improving the thermal conductivity of the adhesive.

[0073] Compared with Example 1, Comparative Example 1 uses boron nitride instead of modified boron nitride, and the hydrolysis resistance, water absorption, volume shrinkage rate, and thermal conductivity of the adhesive all decrease to varying degrees; Comparative Example 2 uses tripropylene glycol diacrylate instead of methacrylate monomer, and the thermal conductivity of the adhesive decreases significantly, indicating that the thermal conductivity of the adhesive is poor.

[0074] In summary, by introducing the newly synthesized methacrylate monomer, the adhesive has excellent hydrolysis resistance, the volume shrinkage rate is effectively reduced, and the thermal conductivity of the adhesive is improved. In addition, the introduction of modified boron nitride in the adhesive can reduce the agglomeration of boron nitride, improve its dispersibility and compatibility, and further improve the thermal conductivity of the adhesive.

[0075] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and substitutions made by those skilled in the art based on the present application are within the scope of the present application.

Claims

1. A high thermal conductivity adhesive for electronic packaging, characterized in that, The high thermal conductivity electronic packaging adhesive comprises, by weight, 55-60 parts of acrylate monomer, 40-45 parts of methacrylate monomer, 0.5-5 parts of photoinitiator, 10-25 parts of modified boron nitride, 1-3 parts of thixotropic agent, 0.2-1 parts of defoamer, and 0.5-1 parts of antioxidant. The preparation process of the modified boron nitride is as follows: Boron nitride was dispersed in sodium hydroxide solution and treated under nitrogen protection. After washing and drying, hydroxy boron nitride was obtained. Then, hydroxy boron nitride was dispersed in solvent, and 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one and sodium hydroxide solution were added and heated to react. After the reaction was completed, the pH of the reaction solution was adjusted to neutral, filtered, washed and dried to obtain modified boron nitride. The chemical structural formula of the methacrylate monomer is: 。 2. The high thermal conductivity electronic packaging adhesive according to claim 1, characterized in that, The volume ratio of boron nitride to sodium hydroxide solution is 1-3g:15-30mL; the volume ratio of 4-bromo-2,3-dihydro-7-[(trifluoromethyl)sulfonyl]-1H-inden-1-one, hydroxy boron nitride, solvent, and sodium hydroxide solution is 1g:3.0-3.2g:30-35mL:0.6-0.8mL, wherein the solvent is acetone; and the concentration of sodium hydroxide solution is 5mol / L.

3. The high thermal conductivity electronic packaging adhesive according to claim 1, characterized in that, The treatment temperature is 90-100℃ and the time is 11-12h; the heating reaction temperature is 70-75℃ and the time is 4-6h.

4. The high thermal conductivity electronic packaging adhesive according to claim 1, characterized in that, The preparation process of the methacrylate monomer is as follows: (1) Under nitrogen protection, 4-(bromomethyl)phenylboronic acid, 5-furfuryl-2-boronic acid, K2CO3 and PdCl2 were added to DMF aqueous solution for heating reaction. After the reaction was completed, the reaction solution was extracted, washed and recrystallized to obtain intermediate 1. (2) Under nitrogen protection, 7-bromo-1-heptanol, intermediate 1, K2CO3 and PdCl2 were added to DMF aqueous solution for heating reaction. After the reaction was completed, the reaction solution was extracted, washed and recrystallized to obtain intermediate 2. (3) Intermediate 2, methacrylic acid, p-toluenesulfonic acid and dibutylhydroxytoluene were added to a toluene solution of DMF to carry out the reaction. The reaction solution was cooled and the pH was adjusted to neutral. After distillation, washing and drying, methacrylate monomer was obtained.

5. The high thermal conductivity electronic packaging adhesive according to claim 4, characterized in that, In step (1), the ratio of the amounts of 4-(bromomethyl)phenylboronic acid, 5-furfuryl-2-boronic acid, K2CO3, PdCl2, and DMF aqueous solution is 5 mmol: 5-5.5 mmol: 5.5-6.5 mmol: 0.5-2 mmol: 10-15 mL; the DMF aqueous solution is obtained by mixing DMF and deionized water in a volume ratio of 10: (0.5-1); the heating reaction temperature is 45-50℃ and the time is 18-24 h.

6. The high thermal conductivity electronic packaging adhesive according to claim 4, characterized in that, In step (2), the ratio of the amounts of 7-bromo-1-heptanol, intermediate 1, K2CO3, PdCl2, and DMF aqueous solution is 5 mmol: 5-5.5 mmol: 5.5-6.5 mmol: 0.5-2 mmol: 12-15 mL; the DMF aqueous solution is obtained by mixing DMF and deionized water in a volume ratio of 10: (0.5-1); the heating reaction temperature is 45-50℃ and the time is 18-24 h.

7. The high thermal conductivity electronic packaging adhesive according to claim 4, characterized in that, In step (3), the ratio of intermediate 2, methacrylic acid, p-toluenesulfonic acid, dibutylhydroxytoluene and DMF toluene solution is 5g:1.8-2g:0.03-0.08g:0.003-0.03g:10-15mL; the DMF toluene solution is obtained by mixing DMF and toluene in a volume ratio of 1:(1-2); the reaction temperature is 90-120℃ and the time is 4-8h.

8. The high thermal conductivity electronic packaging adhesive according to claim 1, characterized in that, The acrylate monomer is tripropylene glycol diacrylate or 1,6-hexanediol diacrylate; the photoinitiator is benzoin dimethyl ether; the thixotropic agent is fumed silica; the defoamer is defoamer BYK-1790; and the antioxidant is at least one of antioxidant 1010, antioxidant 1072, or antioxidant 1024.

9. The method for preparing the high thermal conductivity electronic packaging adhesive according to any one of claims 1-8, characterized in that, Includes the following steps: The acrylate monomer, methacrylate monomer, modified boron nitride, thixotropic agent, defoamer and antioxidant are mixed evenly, and then a photoinitiator is added. The mixture is then evacuated to -0.1~-0.08MPa, and stirred under pressure for 3-5 hours. After vacuum defoaming and discharge, the high thermal conductivity electronic packaging adhesive is obtained.

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