Polyimide adhesive for power semiconductor packaging and preparation method thereof

Abstract

The present invention discloses a polyimide adhesive for power semiconductor packaging, which is randomly copolymerized with an aromatic diamine containing a siloxane structure, a meta-aromatic diamine containing a carbonyl group, and an aromatic dianhydride containing an ether bond as monomers. The preparation method comprises: in an inert atmosphere, dissolving the aromatic diamine containing a siloxane structure and the meta-aromatic diamine containing a carbonyl group in a polar aprotic solvent; then adding the aromatic dianhydride containing an ether bond to carry out a copolymerization reaction to obtain a polyamic acid resin; then adding an amino-terminated silane compound and stirring the reaction, and obtaining the polyimide adhesive for power semiconductor packaging after the reaction is completed. The polyimide adhesive for power semiconductor packaging of the present invention is fully cured below 300°C, has high compatibility with the manufacturing process of power semiconductor devices, has good low-temperature storage stability, and has strong resistance to solvent cleaning agents such as acidic degreasing cleaning agents, neutral degreasing cleaning agents, and dewaxing cleaning agents.

Description

Technical Field

[0001] The present invention relates to the field of adhesives, and in particular to a polyimide adhesive for power semiconductor packaging having good adhesion, solvent resistance, compatibility with device manufacturing processes, and good long-term reliability for devices, and a preparation method thereof. Background Art

[0002] After thermal imidization, polyimide adhesive (PI adhesive) for power semiconductor packaging not only retains the excellent physical and chemical properties of polyimide itself, but also exhibits excellent bonding properties to materials such as silicon wafers, aluminum, copper, glass, or ceramics. It can be applied to the surface of electronic components as a protective coating and can also bond composite materials, aluminum alloys, stainless steel, and other materials. However, currently produced domestically for power semiconductor packaging, PI adhesives have certain deficiencies in adhesion, solvent resistance, compatibility with device manufacturing processes, and long-term reliability.

[0003] Patent document No. 201210548934 discloses a method for preparing a polyimide adhesive. The method involves reacting aromatic diamines BAPP and ODA with aromatic dianhydride α-ODPA to form a polyamide acid solution, which is then chemically imidized to produce PI powder. This PI powder significantly reduces the curing temperature (requiring only 170-200°C), improves the heat resistance rating (210-230°C), and is less susceptible to bubbles or voids within the adhesive layer. However, test results indicate that its bonding strength with copper, aluminum, platinum, and stainless steel is relatively average. While it can be initially used and promoted in power semiconductor applications where bonding requirements are less stringent, it is difficult to implement when bonding requirements are more stringent. Furthermore, the polyimide adhesive has poor solvent resistance and is prone to surface cracking during the power semiconductor manufacturing process.

[0004] Patent document No. 201010561806 discloses a polyimide electronic packaging material and a synthesis method thereof. The method comprises dissolving 2,3,3',4'-biphenyltetracarboxylic dianhydride and 2,2'-bis(trifluoromethyl)-4,4-diaminodiphenyl sulfide in an equal molar ratio in an aprotic polar solvent, and reacting the mixture at 10°C to 20°C to prepare polyamic acid. The prepared polyamic acid is then placed in an oven for imidization according to the following procedure: 80°C / 3h, 150°C / 1h, 180°C / 1h, 250°C / 1h, 300°C / 1h, and 350°C / 15min. The polyimide material for power semiconductor packaging is obtained after natural cooling. This material has high light transmittance, low water absorption, excellent mechanical properties and high temperature resistance, but its glass transition temperature is generally higher than 300°C. During the power semiconductor packaging process, incomplete thermal imidization will occur, thereby affecting the yield and long-term operation reliability of power semiconductor devices. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a polyimide adhesive for power semiconductor packaging and a preparation method thereof.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] A polyimide adhesive for power semiconductor packaging is prepared by random copolymerization of aromatic diamine containing a siloxane structure, meta-aromatic diamine containing a carbonyl group and aromatic dianhydride containing an ether bond as monomers.

[0008] The polyimide adhesive for power semiconductor packaging is preferably terminated with amino-terminated silane compounds.

[0009] As a general inventive concept, the present invention also provides a method for preparing the above-mentioned polyimide adhesive for power semiconductor packaging, comprising the following steps:

[0010] (1) In an inert atmosphere, dissolving an aromatic diamine containing a siloxane structure and a meta-aromatic diamine containing a carbonyl group in a polar aprotic solvent;

[0011] (2) adding an aromatic dianhydride containing an ether bond to the system after step (1) to carry out copolymerization reaction to obtain a polyamic acid resin;

[0012] (3) adding an amino-terminated silane compound to the reaction product after step (2) and stirring the mixture for reaction, and obtaining a polyimide adhesive for power semiconductor packaging after the reaction is completed.

[0013] In the above preparation method, preferably, the molar ratio of the aromatic diamine containing a siloxane structure to the meta-aromatic diamine containing a carbonyl group is 1.00:(8.00-10.00);

[0014] The molar ratio of the total molar amount of the aromatic diamine containing a siloxane structure and the meta-aromatic diamine containing a carbonyl group to the aromatic dianhydride containing an ether bond is 1.00:(0.98-1.00).

[0015] In the above preparation method, preferably, the aromatic diamine containing a siloxane structure is selected from one or more of bis(4-aminophenoxy)dimethylsilane, bis(4-aminophenoxy)diisopropylsilane, bis(4-aminophenoxy)di-tert-butylsilane, bis(4-aminophenoxy)dicyclopentylsilane, and bis(4-aminophenoxy)diphenylsilane;

[0016] The carbonyl-containing meta-aromatic diamine is selected from 3,5-diaminobenzophenone, 3,5-diamino-4'-n-decylbenzophenone, 3,5-diamino-4'-n-undecylbenzophenone, 3,5-diamino-4'-n-dodecylbenzophenone, 3,5-diamino-4'-n-tridecylbenzophenone, 3,5-diamino-4'-n-tetradecylbenzophenone, 3,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, Methyl aminobenzoate, butyl 3,5-diaminobenzoate, octyl 3,5-diaminobenzoate, dodecyl 3,5-diaminobenzoate, hexadecyl 3,5-diaminobenzoate, octadecyl 3,5-diaminobenzoate, ethylene glycol 3,5-diaminobenzoate, phenyl 3,5-diaminobenzoate, 1,4-dimethylbenzene monoester of 3,5-diaminobenzoate, 4-biphenyl 3,5-diaminobenzoate Ester, 4-(4'-butoxy)biphenyl 3,5-diaminobenzoate, 4-(4'-hexyloxy)biphenyl 3,5-diaminobenzoate, 4-(4'-dodecyloxy)biphenyl 3,5-diaminobenzoate, 4'-(tert-butyldimethylsilyl)biphenyl 3,5-diaminobenzoate, 4-(3,4,5-tri-n-pentyloxy)benzyl 3,5-diaminobenzoate, -diaminobenzoic acid-4-(3,4,5-tri-n-hexyloxy)benzyl ester, 3,5-diaminobenzoic acid-4-(3,4,5-tri-n-octyloxy)benzyl ester, 3,5-diaminobenzoic acid-4-(3,4,5-tri-n-dodecyloxy)benzyl ester, 3,5-diaminobenzoic acid-2-(4-phenylphenoxyethyl ester), 3,5-diaminobenzoic acid-2-(4-phenylphenoxyhexyl ester) One or more.

[0017] In the above preparation method, preferably, the aromatic dianhydride containing an ether bond is selected from one or more of 3,4,3',4'-diphenyl ether dianhydride, 2,3,2',3'-diphenyl ether dianhydride, 2,3,3',4'-diphenyl ether dianhydride, 4,4'-(p-phenylene) diether dianhydride, 3,3'-(p-phenylene) diether dianhydride, 4,4'-(isophenylene) diether dianhydride, 3,3'-(isophenylene) diether dianhydride, and 4,4'-(o-phenylene) diether dianhydride.

[0018] In the above preparation method, preferably, the amino-terminated silane compound is selected from one or more of Shin-Etsu KBM-602, Shin-Etsu KBM-603, Shin-Etsu KBM-903, and Shin-Etsu KBE-903, and the added amount of the amino-terminated silane compound is 0.1-2.0% of the mass of the polyimide glue.

[0019] In the above preparation method, preferably, the aprotic solvent is selected from one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and the addition amount thereof is 70.0-90.0% of the mass of the polyimide glue.

[0020] In the above preparation method, preferably, in step (2), the reaction temperature is 0-5°C and the reaction time is 6-8h.

[0021] In the above preparation method, preferably, in step (3), the stirring reaction rate is 100-150 r / min, the reaction time is 2-3 h, and the stirring temperature is 0-5°C.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] (1) The polyimide adhesive for power semiconductor packaging of the present invention is prepared by random copolymerization of aromatic diamine containing a siloxane structure, meta-aromatic diamine containing a carbonyl group, and aromatic dianhydride containing an ether bond as monomers. The combined action of the three can weaken the stacking regularity between the polyamic acid molecular chains, ensuring that the prepared polyimide adhesive can be fully cured below 300°C, and is highly compatible with the manufacturing process of power semiconductor devices.

[0024] (2) The present invention introduces terminal aminosilane compounds into the polyimide glue for power semiconductor packaging for end-capping, which can ensure that the polyamic acid resin has excellent low-temperature storage stability and synergistically improve the adhesion performance.

[0025] (3) By regulating the ratio of the comonomers, the cured polyimide has a strong resistance to solvent cleaning agents such as acidic degreasing cleaning agents, neutral degreasing cleaning agents, and wax removal cleaning agents. After solvent cleaning, the surface is not damaged, which can achieve good packaging of power semiconductors, protect the internal interconnection of the device, and prevent the device from mechanical and chemical damage. DETAILED DESCRIPTION

[0026] In order to facilitate understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0027] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0028] Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available products or products that can be prepared by known methods.

[0029] Example 1:

[0030] The polyimide adhesive for power semiconductor packaging of this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)dimethylsilane, 3,5-diamino-4'-n-decyldiphenyl, and 3,4,3',4'-diphenyl ether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-602.

[0031] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0032] (1) Under nitrogen atmosphere, 0.005 mol (1.37 g) of bis(4-aminophenoxy)dimethylsilane and 0.05 mol (17.60 g) of 3,5-diamino-4'-n-decylbenzophenone were dissolved in 204.11 g of N-methylpyrrolidone;

[0033] (2) adding 0.055 mol (17.05 g) of 3,4,3',4'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 hours to obtain a polyamic acid resin;

[0034] (3) Add 0.36 g of Shin-Etsu KBM-602 to the polyamic acid resin obtained in step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0035] Example 2:

[0036] The polyimide adhesive for power semiconductor packaging of this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)dimethylsilane, 3,5-diamino-4'-n-undecylbenzophenone, and 3,4,3',4'-diphenyl ether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-602.

[0037] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0038] (1) Under nitrogen atmosphere, 0.005 mol (1.37 g) of bis(4-aminophenoxy)dimethylsilane and 0.05 mol (18.30 g) of 3,5-diamino-4'-n-undecylbenzophenone were dissolved in 208.08 g of N-methylpyrrolidone;

[0039] (2) adding 0.055 mol (17.05 g) of 3,4,3',4'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 4° C., and reacting for 8 hours to obtain a polyamic acid resin;

[0040] (3) Add 0.36 g of Shin-Etsu KBM-602 to the polyamic acid resin obtained in step (2), and stir for 3 h to allow it to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0041] Example 3:

[0042] The polyimide adhesive for power semiconductor packaging of this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)diisopropylsilane, 3,5-diaminobenzoic acid methyl ester, and 3,4,3',4'-diphenyl ether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-602.

[0043] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0044] (1) Under nitrogen atmosphere, 0.005 mol (1.51 g) of bis(4-aminophenoxy)diisopropylsilane and 0.05 mol (8.30 g) of methyl 3,5-diaminobenzoate were dissolved in 152.21 g of N-methylpyrrolidone;

[0045] (2) adding 0.055 mol (17.05 g) of 3,4,3',4'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 h to obtain a polyamic acid resin;

[0046] (3) Add 0.30 g of Shin-Etsu KBM-602 to the polyamic acid resin obtained as the reaction product in step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide glue for power semiconductor packaging.

[0047] Example 4:

[0048] The polyimide adhesive for power semiconductor packaging of this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)diisopropylsilane, 3,5-diaminobenzoic acid ethylene glycol, and 3,4,3',4'-diphenyl ether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-602.

[0049] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0050] (1) Under nitrogen atmosphere, 0.005 mol (1.51 g) of bis(4-aminophenoxy)diisopropylsilane and 0.05 mol (9.80 g) of ethylene glycol 3,5-diaminobenzoate were dissolved in 160.71 g of N-methylpyrrolidone;

[0051] (2) adding 0.055 mol (17.05 g) of 3,4,3',4'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 h to obtain a polyamic acid resin;

[0052] (3) Add 0.32 g of Shin-Etsu KBM-602 to the polyamic acid resin obtained in step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0053] Example 5:

[0054] The polyimide adhesive for power semiconductor packaging of this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)dicyclopentylsilane, 3,5-diaminobenzoic acid-4-biphenyl ester, and 3,4,3',4'-diphenyl ether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-603.

[0055] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0056] (1) Under nitrogen atmosphere, 0.005 mol (1.64 g) of bis(4-aminophenoxy)dicyclopentylsilane and 0.05 mol (15.20 g) of 4-biphenyl 3,5-diaminobenzoate were dissolved in 192.04 g of N-methylpyrrolidone;

[0057] (2) adding 0.055 mol (17.05 g) of 3,4,3',4'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 h to obtain a polyamic acid resin;

[0058] (3) Add 0.36 g of Shin-Etsu KBM-603 to the polyamic acid resin obtained in step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0059] Example 6:

[0060] The polyimide adhesive for power semiconductor packaging in this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)dicyclopentylsilane, 3,5-diamino-4'-n-decylbenzophenone, and 2,3,2',3'-diphenyl ether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-903.

[0061] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0062] (1) Under nitrogen atmosphere, 0.005 mol (1.64 g) of bis(4-aminophenoxy)dicyclopentylsilane and 0.05 mol (17.60 g) of 3,5-diamino-4'-n-decylbenzophenone were dissolved in 205.64 g of N-methylpyrrolidone;

[0063] (2) adding 0.055 mol (17.05 g) of 2,3,2',3'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 hours to obtain a polyamic acid resin;

[0064] (3) Add 0.32 g of Shin-Etsu KBM-903 to the polyamic acid resin obtained in step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0065] Example 7:

[0066] The polyimide adhesive for power semiconductor packaging in this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)diphenylsilane, 3,5-diamino-4'-n-decylbenzophenone, and 4,4'-(terephthalic)ether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-602.

[0067] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0068] (1) Under nitrogen atmosphere, 0.005 mol (1.68 g) of bis(4-aminophenoxy)diphenylsilane and 0.05 mol (17.60 g) of 3,5-diamino-4'-n-decylbenzophenone were dissolved in 234.54 g of N-methylpyrrolidone;

[0069] (2) adding 0.055 mol (22.11 g) of 4,4'-(p-phenylene) diether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5°C, and reacting for 8 hours to obtain a polyamic acid resin;

[0070] (3) Add 0.40 g of Shin-Etsu KBM-602 to the reaction product of step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0071] Example 8:

[0072] The polyimide adhesive for power semiconductor packaging in this embodiment is prepared by random copolymerization of bis(4-aminophenoxy)diphenylsilane, 3,5-diamino-4'-n-decylbenzophenone, and 4,4'-(m-phenylene)diether dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-603.

[0073] The method for preparing the polyimide adhesive for power semiconductor packaging of this embodiment includes the following steps:

[0074] (1) Under nitrogen atmosphere, 0.005 mol (1.68 g) of bis(4-aminophenoxy)diphenylsilane and 0.05 mol (17.60 g) of 3,5-diamino-4'-n-decylbenzophenone were dissolved in 234.54 g of N-methylpyrrolidone;

[0075] (2) adding 0.055 mol (22.11 g) of 4,4'-(isophenylene) diether dianhydride to the system after step (1) in 8 batches for reaction, controlling the reaction temperature to 5°C, and reacting for 8 hours to obtain a polyamic acid resin;

[0076] (3) Add 0.44 g of Shin-Etsu KBM-603 to the reaction product of step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0077] Comparative Example 1:

[0078] The polyimide adhesive for power semiconductor packaging in this comparative example is prepared by random copolymerization of bis(4-aminophenoxy)dimethylsilane, 3,5-diamino-4'-n-decyldiphenyl, and 3,4,3',4'-diphenyl ether dianhydride as monomers, but without adding Shin-Etsu KBM-603, thereby obtaining an uncapped polyimide adhesive for power semiconductor packaging.

[0079] The preparation method of the polyimide adhesive for power semiconductor packaging of this comparative example comprises the following steps:

[0080] (1) Under nitrogen atmosphere, 0.005 mol (1.37 g) of bis(4-aminophenoxy)dimethylsilane and 0.05 mol (17.60 g) of 3,5-diamino-4'-n-decylbenzophenone were dissolved in 204.11 g of N-methylpyrrolidone;

[0081] (2) adding 0.055 mol (17.05 g) of 3,4,3',4'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 h to obtain a polyamic acid resin;

[0082] (3) Then continue stirring for 3 hours to obtain an uncapped polyimide adhesive for power semiconductor packaging.

[0083] Comparative Example 2:

[0084] The polyimide adhesive for power semiconductor packaging in this comparative example is prepared by random copolymerization of bis(4-aminophenoxy)dimethylsilane, 3,5-diamino-4'-n-decyldiphenyl, and pyromellitic dianhydride as monomers, and the polyimide adhesive is end-capped with Shin-Etsu KBM-603 to obtain a polyimide adhesive for power semiconductor packaging with a high glass transition temperature.

[0085] The preparation method of the polyimide adhesive for power semiconductor packaging of this comparative example comprises the following steps:

[0086] (1) Under nitrogen atmosphere, 0.005 mol (1.37 g) of bis(4-aminophenoxy)dimethylsilane and 0.05 mol (17.60 g) of 3,5-diamino-4'-n-decylbenzophenone were dissolved in 175.50 g of N-methylpyrrolidone;

[0087] (2) adding 0.055 mol (12.00 g) of pyromellitic dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 h to obtain a polyamic acid resin;

[0088] (3) Add 0.44 g of Shin-Etsu KBM-603 to the reaction product of step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging with a high glass transition temperature.

[0089] Comparative Example 3:

[0090] The polyimide glue for power semiconductor packaging in this comparative example is prepared by random copolymerization of bis(4-aminophenoxy)dimethylsilane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 3,4,3',4'-diphenyl ether dianhydride as monomers, and the polyimide glue is end-capped with Shin-Etsu KBM-603 to obtain a polyimide glue for power semiconductor packaging.

[0091] The preparation method of the polyimide adhesive for power semiconductor packaging of this comparative example comprises the following steps:

[0092] (1) Under nitrogen atmosphere, 0.005 mol (1.37 g) of bis(4-aminophenoxy)dimethylsilane and 0.05 mol (20.53 g) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane were dissolved in 220.72 g of N-methylpyrrolidone;

[0093] (2) adding 0.055 mol (17.05 g) of 3,4,3',4'-diphenyl ether dianhydride to the system after step (1) in 8 batches to react, controlling the reaction temperature to 5° C., and reacting for 8 h to obtain a polyamic acid resin;

[0094] (3) Add 0.44 g of Shin-Etsu KBM-603 to the reaction product of step (2), and stir for 3 h to react with the terminal anhydride in the polyamic acid to obtain a polyimide adhesive for power semiconductor packaging.

[0095] The viscosity of the polyamic acid adhesives prepared in the above examples and comparative examples was tested according to GB / T 2794-1995 standard. The results are shown in Table 1.

[0096] Table 1 Viscosity of polyamic acid glue prepared in various examples and comparative examples

[0097] Implementation Cases Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Viscosity, cP 1540 1500 1550 1510 1580 1580 serial number Example 7 Example 8 Comparative Example 1 Comparative Example 2 Comparative Example 3 Viscosity, cP 1560 1570 2200 3080 2540

[0098] As can be seen from Table 1, the polyamic acid of the present invention has suitable viscosity and good fluidity. When coated on a substrate or a product, it is not easy to generate bubbles and has good leveling properties.

[0099] The physical and chemical properties of the polyamide acid glue prepared in the above examples and comparative examples were tested, and the results are shown in Table 2, wherein the glass transition temperature (T g ) is tested in accordance with HB 7655-1999 standard; the insulation strength is tested in accordance with GB / T 1408.1-2016 standard; the bonding strength is tested in accordance with GB / T 5210-2006 standard; the cross-cut test is tested in accordance with GB / T9286-2021 standard. Low-temperature stability is mainly determined by testing its viscosity after storage at low temperature for a period of time. If its viscosity changes by more than 15%, it is judged to be deteriorated. If its viscosity changes by less than 15%, it indicates that it has good low-temperature stability. The basis for judging solvent resistance is the resistance of the cured polyimide to solvent cleaning agents such as acidic degreasing cleaners, neutral degreasing cleaners, and wax removal cleaners. If there is no damage to the surface after solvent cleaning, it is judged to have excellent solvent resistance. If cracks or other defects appear on the surface after solvent cleaning, it is judged to have poor solvent resistance.

[0100] Table 2 Physical and chemical properties of polyamide acid glue prepared in various examples and comparative examples

[0101] Test items <![CDATA[T g ,℃]]> Dielectric strength, kV / mm Bond strength, MPa Cross-cut test, 0-5 levels Low temperature storage stability Solvent resistance Example 1 283.4 280.3 10.5 Level 0 ≥180 days After cleaning, no cracks Example 2 282.3 282.6 10.6 Level 0 ≥180 days After cleaning, no cracks Example 3 292.1 281.2 10.2 Level 0 ≥180 days After cleaning, no cracks Example 4 287.2 280.7 10.5 Level 0 ≥180 days After cleaning, no cracks Example 5 283.6 281.8 10.7 Level 0 ≥180 days After cleaning, no cracks Example 6 274.2 282.4 11.0 Level 0 ≥180 days After cleaning, no cracks Example 7 276.3 285.8 10.1 Level 0 ≥180 days After cleaning, no cracks Example 8 275.9 286.3 10.2 Level 0 ≥180 days After cleaning, no cracks Comparative Example 1 378.6 280.5 8.9 Level 4 ≤120 days After cleaning, no cracks Comparative Example 2 378.2 340.5 5.4 Level 5 ≥180 days After cleaning, no cracks Comparative Example 3 240.7 260.2 4.3 Level 5 ≥180 days After cleaning, there are cracks

[0102] Compared with Example 1, since Shin-Etsu KBM-603 was not added in the late stage of polymerization, the polyimide glue for power semiconductor packaging obtained had active groups at the end, and its storage stability was significantly reduced. After 120 days of low-temperature storage, its viscosity was significantly reduced, and the decline was more than 15%, indicating that it had deteriorated, indicating that its low-temperature storage stability did not exceed 120 days. Compared with Example 1, since the aromatic dianhydride containing ether bonds (3,4,3',4'-diphenyl ether dianhydride) was replaced with highly rigid pyromellitic dianhydride, the glass transition temperature of the prepared polyimide glue for power semiconductor packaging was as high as 340.5°C, and the adhesion performance was reduced. During the power semiconductor packaging process, the problem of incomplete thermal imidization occurred, and the compatibility with the manufacturing process of power semiconductor devices was poor, affecting the yield rate and long-term operational reliability of power semiconductor devices. Compared with Example 1, in Comparative Example 3, the solvent resistance and adhesion properties of the prepared polyimide adhesive for power semiconductor packaging are reduced due to the replacement of the carbonyl-containing meta-aromatic diamine (3,5-diamino-4'-n-decyldibenzophenone) with 2,2-bis[4-(4-aminophenoxy)phenyl]propane having higher molecular flexibility.

Claims

1. A polyimide adhesive for power semiconductor packaging, characterized in that: It is prepared by random copolymerization of aromatic diamine containing siloxane structure, meta-aromatic diamine containing carbonyl group and aromatic dianhydride containing ether bond as monomers; The polyimide glue is end-capped with amino-terminated silane compounds; The aromatic diamine containing a siloxane structure is selected from one or more of bis(4-aminophenoxy)dimethylsilane, bis(4-aminophenoxy)diisopropylsilane, bis(4-aminophenoxy)di-tert-butylsilane, bis(4-aminophenoxy)dicyclopentylsilane, and bis(4-aminophenoxy)diphenylsilane; The carbonyl-containing meta-aromatic diamine is selected from 3,5-diaminobenzophenone, 3,5-diamino-4'-n-decylbenzophenone, 3,5-diamino-4'-n-undecylbenzophenone, 3,5-diamino-4'-n-dodecylbenzophenone, 3,5-diamino-4'-n-tridecylbenzophenone, 3,5-diamino-4'-n-tetradecylbenzophenone, 3,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, Methyl aminobenzoate, butyl 3,5-diaminobenzoate, octyl 3,5-diaminobenzoate, dodecyl 3,5-diaminobenzoate, hexadecyl 3,5-diaminobenzoate, octadecyl 3,5-diaminobenzoate, ethylene glycol 3,5-diaminobenzoate, phenyl 3,5-diaminobenzoate, 1,4-dimethylbenzene monoester of 3,5-diaminobenzoate, 4-biphenyl 3,5-diaminobenzoate Ester, 4-(4'-butoxy)biphenyl 3,5-diaminobenzoate, 4-(4'-hexyloxy)biphenyl 3,5-diaminobenzoate, 4-(4'-dodecyloxy)biphenyl 3,5-diaminobenzoate, 4'-(tert-butyldimethylsilyl)biphenyl 3,5-diaminobenzoate, 4-(3,4,5-tri-n-pentyloxy)benzyl 3,5-diaminobenzoate, - one or more of 4-(3,4,5-tri-n-hexyloxy)benzyl diaminobenzoate, 4-(3,4,5-tri-n-octyloxy)benzyl 3,5-diaminobenzoate, 4-(3,4,5-tri-n-dodecyloxy)benzyl 3,5-diaminobenzoate, 2-(4-phenylphenoxyethyl 3,5-diaminobenzoate), and 2-(4-phenylphenoxyhexyl 3,5-diaminobenzoate; The aromatic dianhydride containing an ether bond is selected from one or more of 3,4,3',4'-diphenyl ether dianhydride, 2,3,2',3'-diphenyl ether dianhydride, 2,3,3',4'-diphenyl ether dianhydride, 4,4'-(p-phenylene) diether dianhydride, 3,3'-(p-phenylene) diether dianhydride, 4,4'-(m-phenylene) diether dianhydride, 3,3'-(m-phenylene) diether dianhydride, and 4,4'-(o-phenylene) diether dianhydride; The molar ratio of the aromatic diamine containing a siloxane structure to the meta-aromatic diamine containing a carbonyl group is 1.00:(8.00-10.00); The molar ratio of the total molar amount of the aromatic diamine containing a siloxane structure and the meta-aromatic diamine containing a carbonyl group to the aromatic dianhydride containing an ether bond is 1.00:(0.98-1.00).

2. A method for preparing a polyimide adhesive for power semiconductor packaging according to claim 1, characterized in that: The following steps are involved: (1) In an inert atmosphere, an aromatic diamine containing a siloxane structure and a meta-aromatic diamine containing a carbonyl group are dissolved in a polar aprotic solvent; (2) adding an aromatic dianhydride containing an ether bond to the system after step (1) to carry out copolymerization reaction to obtain a polyamic acid resin; (3) Adding an amino-terminated silane compound to the reaction product after step (2) and stirring the mixture to react, and obtaining a polyimide adhesive for power semiconductor packaging after the reaction is completed.

3. The preparation method according to claim 2, wherein The amino-terminated silane compound is selected from one or more of Shin-Etsu KBM-602, Shin-Etsu KBM-603, Shin-Etsu KBM-903, and Shin-Etsu KBE-903, and the added amount of the amino-terminated silane compound is 0.1-2.0% of the mass of the polyimide adhesive.

4. The preparation method according to claim 2, wherein The aprotic solvent is selected from one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and its addition amount is 70.0-90.0% of the mass of the polyimide glue.

5. The preparation method according to claim 2, wherein In step (2), the reaction temperature is 0-5°C and the reaction time is 6-8h.

6. The preparation method according to claim 2, wherein In step (3), the stirring reaction rate is 100-150 r / min, the reaction time is 2-3 h, and the stirring temperature is 0-5°C.