A waterproof lead frame for semiconductor packaging and its manufacturing method

Abstract

The present invention relates to the technical field of lead frames, and specifically to a waterproof lead frame for semiconductor packaging and a manufacturing method thereof. In the present invention, modified graphene oxide is ultrasonically dispersed in deionized water, heated to 40-50 °C, and then mixed uniformly with modified halloysite nanotubes. Next, waterborne epoxy resin, a curing agent, a leveling agent, and an antifoaming agent are added and mixed uniformly to obtain a waterproof coating material. The lead frame is successively subjected to electro-degreasing, pickling, and plasma cleaning to obtain a pretreated lead frame. The waterproof coating material is coated on the surface of the pretreated lead frame, and after curing, a waterproof coating is formed to obtain a waterproof lead frame. The waterproof lead frame prepared by the present invention not only has excellent waterproof performance but also has excellent corrosion resistance, and can effectively extend the service life of the lead frame.

Description

Technical Field

[0001] The present invention relates to the technical field of lead frames, and particularly to a waterproof lead frame for semiconductor packaging and a manufacturing method thereof. Background Art

[0002] With the development trend of electronic products towards miniaturization, high integration, and high performance, packaging technology is also constantly advancing. A lead frame is used as a mechanical support carrier for semiconductor chips, and through leads (bonding wires or copper wires), the internal circuit leads of the chips are electrically connected to the external leads through internal leads to form a key component of an electrical circuit. In semiconductor chip packaging, the lead frame mainly functions to stabilize the chip, conduct signals, and dissipate the heat generated during the operation of the chip.

[0003] The materials of lead frames are generally copper-based alloys and iron-nickel alloys. Copper-based alloys are widely used in the manufacture of semiconductor lead frames due to their high strength, high electrical conductivity, excellent thermal conductivity, and low price. However, the existing copper-based alloy lead frames are usually weak in waterproof design and cannot effectively prevent the penetration of moisture and humidity. This defect is particularly obvious in humid or extreme environments, which may lead to problems such as corrosion of internal electronic components and insulation failure, thereby reducing the reliability of the entire package.

[0004] Therefore, we propose a waterproof lead frame for semiconductor packaging and a manufacturing method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a waterproof lead frame for semiconductor packaging and a manufacturing method thereof to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A manufacturing method of a waterproof lead frame for semiconductor packaging includes the following steps:

[0008] Step S1: Ultrasonically disperse modified graphene oxide in deionized water, heat it up to 40 - 50 °C, add modified halloysite nanotubes and mix evenly, then add water-based epoxy resin, curing agent, leveling agent, and defoaming agent and mix evenly to obtain a waterproof coating material;

[0009] Step S2: Subject the lead frame to electro-degreasing, pickling, and plasma cleaning in sequence to obtain a pretreated lead frame;

[0010] Step S3: Coat the pretreated lead frame with the waterproof coating material, and after curing, form a waterproof coating to obtain a waterproof lead frame.

[0011] Further, the anticorrosive coating comprises the following weight components: 60-80 parts of waterborne epoxy resin, 80-100 parts of deionized water, 3-5 parts of modified graphene oxide, 5-10 parts of modified halloysite nanotubes, 8-12 parts of curing agent, 0.1-0.3 part of leveling agent, and 0.1-0.2 part of defoaming agent.

[0012] Further, the preparation method of the modified graphene oxide is as follows:

[0013] Step (1): Ultrasonically disperse graphene oxide in N, N-dimethylformamide, add triphenylphosphine and hydroquinone, heat up to 100-120 °C, add castor oil triglycidyl ether, react for 10-12 h, then add n-octadecanethiol and photoinitiator and mix evenly. After ultraviolet light irradiation, filtration, washing, and drying, an intermediate is obtained;

[0014] Step (2): Ultrasonically disperse the intermediate in N, N-dimethylformamide, add bis(amino-terminated) polydimethylsiloxane, adjust the pH to 6-8 with sodium hydroxide, react at 30-40 °C for 20-24 h, and after filtration, washing, and drying, modified graphene oxide is obtained.

[0015] Further, in the step (1), the mass ratio of graphene oxide, N, N-dimethylformamide, triphenylphosphine, hydroquinone, and castor oil triglycidyl ether is 1: (100-200): (0.03-0.05): (0.005-0.008): (8-12).

[0016] Further, in the step (1), the mass ratio of castor oil triglycidyl ether, n-octadecanethiol, and photoinitiator is 1: (1.0-1.2): (0.1-0.3), and the photoinitiator is 2-hydroxy-2-methylpropiophenone.

[0017] Further, the process conditions of the ultraviolet light irradiation are: irradiation wavelength 360-400 nm, irradiation time 30-50 min, irradiation intensity 20-35 mW / cm 2 .

[0018] Further, in the step (2), the mass ratio of the intermediate, N, N-dimethylformamide, and bis(amino-terminated) polydimethylsiloxane is 1: (100-200): (2-4).

[0019] Further, the preparation method of the modified halloysite nanotubes is as follows:

[0020] Step A: Mix halloysite nanotubes and sodium hydroxide solution evenly, perform ultrasonic treatment at 40 - 50 °C for 1 - 2 h, and after centrifugation, washing, and drying, obtain alkali-treated halloysite nanotubes; stir the alkali-treated halloysite nanotubes and ethanol solution of benzotriazole for 44 - 48 h, perform vacuum extraction for 1 - 2 h, then stand still at normal pressure for 30 - 50 min, and after filtration, washing, and drying, obtain supported halloysite nanotubes;

[0021] Step B: Under nitrogen protection, mix polyvinylpyrrolidone and absolute ethanol evenly, then add glycidyl methacrylate, heat up to 70 - 80 °C, add azobisisobutyronitrile, and react for 8 - 10 h. After washing and drying, obtain polyglycidyl methacrylate;

[0022] Step C: Mix the supported halloysite nanotubes, absolute ethanol, deionized water, and 3-aminopropyltrimethoxysilane evenly, react at 70 - 80 °C for 4 - 6 h, and after filtration, washing, and drying, obtain amino-functionalized halloysite nanotubes; mix the amino-functionalized halloysite nanotubes and polyglycidyl methacrylate evenly, add deionized water for ultrasonic dispersion, and react at 40 - 50 °C for 22 - 24 h. After filtration, washing, and drying, obtain modified halloysite nanotubes.

[0023] Further, in the said Step A, the mass ratio of halloysite nanotubes to sodium hydroxide solution is 1:(15 - 20), and the concentration of sodium hydroxide solution is 3 - 5 mol / L.

[0024] Further, in the said Step A, the mass ratio of alkali-treated halloysite nanotubes to ethanol solution of benzotriazole is 1:(30 - 40), and the concentration of ethanol solution of benzotriazole is 40 mg / mL.

[0025] Further, in the said Step B, the mass ratio of polyvinylpyrrolidone, absolute ethanol, glycidyl methacrylate, and azobisisobutyronitrile is 1:(50 - 60):(3 - 5):(0.05 - 0.10).

[0026] Further, in the said Step C, the mass ratio of supported halloysite nanotubes to absolute ethanol, deionized water, and 3-aminopropyltrimethoxysilane is 1:(15 - 20):(4 - 6):(1 - 2).

[0027] Further, in the said Step C, the mass ratio of amino-functionalized halloysite nanotubes, polyglycidyl methacrylate, and deionized water is 1:(2 - 3):(100 - 150).

[0028] Further, in the step S2, electro-degreasing: the degreasing solution comprises the following components: 140-145 g / L of sodium chloride, 35-40 g / L of sodium hydroxide, 4-6 g / L of sodium silicate, 2-3 g / L of sodium thiosulfate; the process conditions are: the current density is 0.5-1.0 A / dm², the temperature is 60-70 °C, and the time is 20-30 min.

[0029] Further, in the step S2, pickling: the acid solution comprises the following components: 6-10 wt% of sulfuric acid, 2-4 wt% of ascorbic acid, and the rest is water; the process conditions are: the pickling time is 10-20 s.

[0030] Further, in the step S2, the process conditions of plasma cleaning are: the power is 200-300 w, the vacuum degree is 80-100 Pa, the atmosphere is Ar-H₂, and the cleaning time is 30-60 s.

[0031] Further, the curing agent is isophorone diamine curing agent.

[0032] Further, the thickness of the waterproof coating is 50-150 μm.

[0033] Further, the curing process conditions are: first cure at room temperature for 2-4 h, and then cure at 120-150 °C for 4-6 h.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. For a waterproof lead frame for semiconductor packaging and its manufacturing method of the present invention, poly(glycidyl methacrylate) (PGMA) is synthesized by the free radical polymerization reaction of glycidyl methacrylate (GMA), which contains a large number of epoxy groups; halloysite nanotubes have a certain loading capacity and can be used as a carrier for controlling the release of corrosion inhibitors in the self-healing coating. The corrosion inhibitor benzotriazole is loaded by alkali etching halloysite nanotubes (HNTs) to obtain loaded halloysite nanotubes; then, the surface of the loaded halloysite nanotubes is modified by the hydrolysis of 3-aminopropyltrimethoxysilane to introduce amino groups; finally, the amino groups in the amino-functionalized halloysite nanotubes react with the epoxy groups in PGMA to obtain modified halloysite nanotubes, which not only improve the compatibility between the material and the waterborne epoxy resin matrix, but also the modified halloysite nanotubes and the waterborne epoxy matrix can be co-cured with a curing agent containing amino groups to form a crosslinked network, enhancing the denseness of the coating and improving its anti-corrosion effect.

[0036] 2. A waterproof lead frame for semiconductor packaging and its manufacturing method according to the present invention. Through the ring-opening reaction of the carboxyl group of graphene oxide with the epoxy group in ricinoleic acid triglyceride glycidyl ether, double bonds and long fatty acid chain structures are introduced. Then, by using n-octadecanethiol to react with the double bonds through thiol-ene click chemistry, hydrophobic alkyl chains are grafted, thereby enhancing the hydrophobicity of the material, effectively improving the waterproof performance of the packaging, and ensuring the long-term stability of semiconductor devices.

[0037] Bis(amino)-terminated polydimethylsiloxane (NH2-PDMS-NH2) is an organosilicon oxide polymer. It has good chemical stability, electrical insulation, and weather resistance, and has a high shear resistance. Due to its low surface tension, it has good hydrophobicity and good anti-permeation effect on corrosive anions. Using bis(amino)-terminated polydimethylsiloxane as a bridge, through the reaction of the amino group at one end of its structure with the epoxy group of graphene oxide, modified graphene oxide is obtained. At the same time, the amino group at the other end of the bis(amino)-terminated polydimethylsiloxane structure can also react with the remaining epoxy groups in PGMA to form stable chemical bonds, improving the compatibility and bonding strength between materials, and thus enhancing the overall performance. Specific embodiments

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] In this embodiment, the lead frame: the material is C19400 copper alloy, the thickness is 2 mm, and it is sourced from Shanghai Xinyie Metal Products Co., Ltd.; graphene oxide: the thickness is 1 - 3 nm, the diameter is 4 - 7 μm, and the number of layers is 2 - 5 layers, sourced from Zhejiang Zhitaina Micro New Materials Co., Ltd.; bis(amino)-terminated polydimethylsiloxane: sourced from Shanghai Macklin Biochemical Co., Ltd.; halloysite nanotubes: the outer tube is 10 - 50 nm, the inner diameter is 5 - 20 nm, the length is 0.5 - 3 μm, and the number of crystal layers is 15 - 40, sourced from Angxing New Carbon Materials Changzhou Co., Ltd.; water-based epoxy resin: E51, epoxy equivalent is 184 - 194 g / ep, sourced from Shenzhen Yitian Chemical Co., Ltd.; curing agent: isophorone diamine curing agent, sourced from Zhangjiagang Yarui Chemical Co., Ltd.; leveling agent: model is Keying KYC-615; defoaming agent: model is BYK-028.

[0040] In the following examples and comparative examples, 1 part is equal to 10 g.

[0041] Example 1: A manufacturing method of a waterproof lead frame for semiconductor packaging, including the following processes:

[0042] Step S1: Ultrasonically disperse 3 parts of modified graphene oxide in 80 parts of deionized water, heat up to 40 °C, add 5 parts of modified halloysite nanotubes and mix evenly, then add 60 parts of waterborne epoxy resin, 8 parts of curing agent, 0.1 part of leveling agent and 0.1 part of defoaming agent and mix evenly to obtain a waterproof coating material.

[0043] Step S2: Subject the lead frame to electro-degreasing (the degreasing solution includes the following components: 140 g / L of sodium chloride, 35 g / L of sodium hydroxide, 4 g / L of sodium silicate, 2 g / L of sodium thiosulfate; the process conditions are: current density is 0.5 A / dm, temperature is 60 °C, time is 20 min), pickling (the acid solution includes the following components: 6 wt% of sulfuric acid, 2 wt% of ascorbic acid, and the rest is water; the process condition is: pickling time is 10 s), and plasma cleaning (power is 200 w, vacuum degree is 80 Pa, atmosphere is Ar-H2, cleaning time is 30 s) to obtain a pretreated lead frame.

[0044] Step S3: Coat the pretreated lead frame with the waterproof coating material, cure it at room temperature for 2 h first, and then cure it at 120 °C for 4 h to form a waterproof coating and obtain a waterproof lead frame.

[0045] The preparation method of the modified graphene oxide is as follows:

[0046] Step (1): Ultrasonically disperse 3 parts of graphene oxide in 300 parts of N, N-dimethylformamide, add 0.09 part of triphenylphosphine and 0.015 part of hydroquinone, heat up to 100 °C, add 24 parts of castor oil triglycidyl ether, react for 10 h, then add 24 parts of n-octadecyl mercaptan and 2.4 parts of photoinitiator and mix evenly. After ultraviolet light irradiation (irradiation wavelength 360 nm, irradiation time 30 min, irradiation intensity 20 mW / cm 2 ), filtration, washing, and drying, an intermediate is obtained.

[0047] Step (2): Ultrasonically disperse 3 parts of the intermediate in 300 parts of N, N-dimethylformamide, add 6 parts of bis-aminoterminated polydimethylsiloxane, adjust the pH to 6 with sodium hydroxide, react at 30 °C for 20 h, and after filtration, washing, and drying, the modified graphene oxide is obtained.

[0048] The preparation method of the modified halloysite nanotubes is as follows:

[0049] Step A: Mix 5 parts of halloysite nanotubes and 75 parts of 3 mol / L sodium hydroxide solution evenly, ultrasonically treat for 1 h at 40 °C, and after centrifugation, washing, and drying, obtain alkali-treated halloysite nanotubes; Mix 5 parts of alkali-treated halloysite nanotubes and 150 parts of an ethanol solution of 40 mg / mL benzotriazole and stir for 44 h, perform vacuum extraction for 1 h, then stand still at normal pressure for 30 min, and after filtration, washing, and drying, obtain supported halloysite nanotubes;

[0050] Step B: Under nitrogen protection, mix 4 parts of polyvinylpyrrolidone and 200 parts of absolute ethanol evenly, then add 12 parts of glycidyl methacrylate, heat up to 70 °C, add 0.2 part of azobisisobutyronitrile, react for 8 h, and after washing and drying, obtain polyglycidyl methacrylate;

[0051] Step C: Mix 5 parts of supported halloysite nanotubes, 75 parts of absolute ethanol, 20 parts of deionized water, and 5 parts of 3-aminopropyltrimethoxysilane evenly, react at 70 °C for 4 h, and after filtration, washing, and drying, obtain amino-functionalized halloysite nanotubes; Mix 5 parts of amino-functionalized halloysite nanotubes and 10 parts of polyglycidyl methacrylate evenly, add 500 parts of deionized water for ultrasonic dispersion, and react at 50 °C for 24 h, and after filtration, washing, and drying, obtain modified halloysite nanotubes.

[0052] Example 2: A method for manufacturing a waterproof lead frame for semiconductor packaging, including the following processes:

[0053] Step S1: Ultrasonically disperse 4 parts of modified graphene oxide in 90 parts of deionized water, heat up to 45 °C, add 8 parts of modified halloysite nanotubes and mix evenly, then add 70 parts of waterborne epoxy resin, 10 parts of curing agent, 0.2 part of leveling agent, and 0.15 part of defoaming agent and mix evenly to obtain a waterproof coating material;

[0054] Step S2: Subject the lead frame to electro-degreasing in sequence (the degreasing solution includes the following components: 142 g / L sodium chloride, 38 g / L sodium hydroxide, 5 g / L sodium silicate, 2.5 g / L sodium thiosulfate; the process conditions are: current density is 0.8 A / dm², temperature is 65 °C, time is 25 min), pickling (the acid solution includes the following components: 8 wt% sulfuric acid, 3 wt% ascorbic acid, and the rest is water; the process condition is: pickling time is 15 s), and plasma cleaning (power is 250 w, vacuum degree is 90 Pa, atmosphere is Ar-H₂, cleaning time is 40 s) to obtain a pretreated lead frame;

[0055] Step S3: Coat the pretreated lead frame with the waterproof coating material, first cure at room temperature for 3 h, and then cure at 130 °C for 5 h to form a waterproof coating layer and obtain a waterproof lead frame;

[0056] The preparation method of modified graphene oxide is as follows:

[0057] Step (1): Ultrasonically disperse 4 parts of graphene oxide in 600 parts of N,N-dimethylformamide, add 0.16 part of triphenylphosphine and 0.025 part of hydroquinone, heat up to 110 °C, add 40 parts of castor oil triglycidyl ether, react for 11 h, then add 44 parts of n-octadecanethiol and 8 parts of photoinitiator and mix evenly. After ultraviolet light irradiation (irradiation wavelength 380 nm, irradiation time 40 min, irradiation intensity 30 mW / cm 2 ), filtration, washing, and drying, an intermediate is obtained;

[0058] Step (2): Ultrasonically disperse 4 parts of the intermediate in 600 parts of N,N-dimethylformamide, add 12 parts of bis-amino-terminated polydimethylsiloxane, adjust the pH to 7 with sodium hydroxide, react at 35 °C for 22 h, and after filtration, washing, and drying, modified graphene oxide is obtained;

[0059] The preparation method of modified halloysite nanotubes is as follows:

[0060] Step A: Mix 8 parts of halloysite nanotubes and 140 parts of 4 mol / L sodium hydroxide solution evenly, ultrasonically treat at 45 °C for 1.5 h, and after centrifugation, washing, and drying, alkali-treated halloysite nanotubes are obtained; Mix 8 parts of alkali-treated halloysite nanotubes and 280 parts of 40 mg / mL benzotriazole ethanol solution and stir for 46 h, perform vacuum extraction for 1.5 h, then stand still at normal pressure for 40 min, and after filtration, washing, and drying, supported halloysite nanotubes are obtained;

[0061] Step B: Under nitrogen protection, mix 5 parts of polyvinylpyrrolidone and 275 parts of absolute ethanol evenly, then add 20 parts of glycidyl methacrylate, heat up to 75 °C, add 0.4 part of azobisisobutyronitrile, react for 9 h, and after washing and drying, polyglycidyl methacrylate is obtained;

[0062] Step C: Mix 8 parts of supported halloysite nanotubes, 140 parts of absolute ethanol, 40 parts of deionized water, and 12 parts of 3-aminopropyltrimethoxysilane evenly, react at 75 °C for 5 h, and after filtration, washing, and drying, amino-functionalized halloysite nanotubes are obtained; Mix 8 parts of amino-functionalized halloysite nanotubes and 20 parts of polyglycidyl methacrylate evenly, add 900 parts of deionized water for ultrasonic dispersion, and react at 45 °C for 23 h, and after filtration, washing, and drying, modified halloysite nanotubes are obtained.

[0063] Example 3: A manufacturing method of a waterproof lead frame for semiconductor packaging, including the following processes:

[0064] A manufacturing method of a waterproof lead frame for semiconductor packaging, including the following processes:

[0065] Step S1: Ultrasonically disperse 5 parts of modified graphene oxide in 100 parts of deionized water, heat up to 50 °C, add 10 parts of modified halloysite nanotubes and mix evenly, then add 80 parts of waterborne epoxy resin, 12 parts of curing agent, 0.3 part of leveling agent and 0.2 part of defoaming agent and mix evenly to obtain a waterproof coating material;

[0066] Step S2: Subject the lead frame to electrolytic degreasing in sequence (the degreasing solution includes the following components: 145 g / L of sodium chloride, 40 g / L of sodium hydroxide, 6 g / L of sodium silicate, 3 g / L of sodium thiosulfate; the process conditions are: current density is 1.0 A / dm, temperature is 70 °C, time is 30 min), pickling (the acid solution includes the following components: 10 wt% of sulfuric acid, 4 wt% of ascorbic acid, and the rest is water; the process condition is: pickling time is 20 s), plasma cleaning (power is 300 w, vacuum degree is 100 Pa, atmosphere is Ar-H2, cleaning time is 60 s) to obtain a pretreated lead frame;

[0067] Step S3: Coat the pretreated lead frame with the waterproof coating material, first cure at room temperature for 4 h, and then cure at 150 °C for 6 h to form a waterproof coating, obtaining a waterproof lead frame;

[0068] The preparation method of the modified graphene oxide is as follows:

[0069] Step (1): Ultrasonically disperse 5 parts of graphene oxide in 1000 parts of N, N-dimethylformamide, add 0.25 part of triphenylphosphine and 0.04 part of hydroquinone, heat up to 120 °C, add 60 parts of castor oil triglycidyl ether, react for 12 h, then add 72 parts of n-octadecyl mercaptan and 18 parts of photoinitiator and mix evenly, and after ultraviolet light irradiation (irradiation wavelength 400 nm, irradiation time 50 min, irradiation intensity 35 mW / cm 2 )、filtration、washing、drying to obtain an intermediate;

[0070] Step (2): Ultrasonically disperse 5 parts of the intermediate in 1000 parts of N, N-dimethylformamide, add 20 parts of diamine-terminated polydimethylsiloxane, adjust the pH = 8 with sodium hydroxide, react at 40 °C for 24 h, and after filtration、washing、drying, obtain the modified graphene oxide;

[0071] The preparation method of the modified halloysite nanotubes is as follows:

[0072] Step A: Mix 10 parts of halloysite nanotubes and 200 parts of 5 mol / L sodium hydroxide solution evenly, ultrasonic treat for 2 h at 50 °C, and after centrifugation, washing, and drying, obtain alkali-treated halloysite nanotubes; mix 10 parts of alkali-treated halloysite nanotubes and 400 parts of an ethanol solution of 40 mg / mL benzotriazole, stir for 48 h, perform vacuum extraction for 2 h, then stand still at normal pressure for 50 min, and after filtration, washing, and drying, obtain supported halloysite nanotubes;

[0073] Step B: Under nitrogen protection, mix 6 parts of polyvinylpyrrolidone and 360 parts of absolute ethanol evenly, then add 30 parts of glycidyl methacrylate, heat up to 80 °C, add 0.6 part of azobisisobutyronitrile, react for 10 h, and after washing and drying, obtain polyglycidyl methacrylate;

[0074] Step C: Mix 10 parts of supported halloysite nanotubes, 200 parts of absolute ethanol, 60 parts of deionized water, and 20 parts of 3-aminopropyltrimethoxysilane evenly, react at 80 °C for 6 h, and after filtration, washing, and drying, obtain amino-functionalized halloysite nanotubes; mix 10 parts of amino-functionalized halloysite nanotubes and 30 parts of polyglycidyl methacrylate evenly, add 1500 parts of deionized water for ultrasonic dispersion, then react at 50 °C for 24 h, and after filtration, washing, and drying, obtain modified halloysite nanotubes.

[0075] Comparative Example 1: A method for manufacturing a waterproof lead frame for semiconductor packaging, including the following processes:

[0076] Compared with Example 2, in Comparative Example 1, the modified graphene oxide is replaced with graphene oxide of the same mass, and the other steps are the same as those in Example 2.

[0077] Comparative Example 2: A method for manufacturing a waterproof lead frame for semiconductor packaging, including the following processes:

[0078] Compared with Example 2, in Comparative Example 2, the modified halloysite nanotubes are replaced with supported halloysite nanotubes of the same mass, and the other steps are the same as those in Example 2.

[0079] Comparative Example 3: A method for manufacturing a waterproof lead frame for semiconductor packaging, including the following processes:

[0080] The preparation method of the modified halloysite nanotubes is as follows:

[0081] Step A: Mix 8 parts of halloysite nanotubes and 140 parts of 4 mol / L sodium hydroxide solution evenly, ultrasonically treat for 1.5 h at 45 °C, and after centrifugation, washing, and drying, obtain alkali-treated halloysite nanotubes; mix 8 parts of alkali-treated halloysite nanotubes and 280 parts of an ethanol solution of 40 mg / mL benzotriazole, stir for 46 h, perform vacuum extraction for 1.5 h, then stand still under normal pressure for 40 min, and after filtration, washing, and drying, obtain supported halloysite nanotubes;

[0082] Step B: Under nitrogen protection, mix 5 parts of polyvinylpyrrolidone and 275 parts of absolute ethanol evenly, then add 20 parts of glycidyl methacrylate, heat up to 75 °C, add 0.4 part of azobisisobutyronitrile, react for 9 h, and after washing and drying, obtain polyglycidyl methacrylate;

[0083] Step C: Mix 8 parts of supported halloysite nanotubes, 140 parts of absolute ethanol, 40 parts of deionized water, and 12 parts of 3-aminopropyltrimethoxysilane evenly, react at 75 °C for 5 h, and after filtration, washing, and drying, obtain amino-functionalized halloysite nanotubes; mix 8 parts of amino-functionalized halloysite nanotubes and 4 parts of polyglycidyl methacrylate evenly, add 900 parts of deionized water for ultrasonic dispersion, then react at 45 °C for 23 h, and after filtration, washing, and drying, obtain modified halloysite nanotubes;

[0084] Compared with Example 2, in Step C of Comparative Example 3, the mass ratio of amino-functionalized halloysite nanotubes to polyglycidyl methacrylate is 1:0.5, and other steps are the same as those in Example 2.

[0085] Experiment: Take the waterproof lead frames obtained in Examples 1-3 and Comparative Examples 1-3, prepare specimens, and detect their performances respectively and record the detection results:

[0086] Use a JC2000DM type contact angle measuring instrument to measure the water contact angle, and the volume of deionized water is 2 μL.

[0087] Coating salt spray resistance test: The size of the specimen is ϕ10 mm × 2 mm, draw a "×" on the surface of the waterproof lead frame, then place it in a salt spray test chamber, and under the conditions of a test temperature of (35 ± 2) °C and a pH value of 6.7 - 7.5, use a 5% NaCl solution as the spray medium, conduct a salt spray test for 720 h, adopt a continuous spray method, and perform salt spray aging performance analysis.

[0088] Test results

[0089]

[0090] According to the data in the above table, the following conclusions can be clearly obtained:

[0091] Compared with Examples 1-3, the hydrophobicity and corrosion resistance of the products obtained in Comparative Example 1 and Comparative Example 2 both decreased, indicating that the modified graphene oxide prepared by the present invention has better hydrophobic performance compared with graphene oxide; compared with the supported halloysite nanotubes, the modified halloysite nanotubes prepared by the present invention have better dispersibility and compatibility, thus forming a more uniform composite material with the waterborne epoxy resin matrix and the modified graphene oxide, improving the waterproof and corrosion resistance characteristics of the material.

[0092] Compared with Examples 1-3, the hydrophobicity and corrosion resistance of the product obtained in Comparative Example 3 both decreased. It can be seen that when the addition amount of glycidyl methacrylate is reduced, the reaction sites of epoxy groups on the surface of the modified halloysite nanotubes will decrease, thus affecting the performance of the waterproof coating.

[0093] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

Claims

1. A manufacturing method of a waterproof lead frame for semiconductor packaging, characterized in that: It includes the following steps: Step S1: Ultrasonically disperse modified graphene oxide in deionized water, heat up to 40 - 50 °C, add modified halloysite nanotubes and mix evenly, then add waterborne epoxy resin, curing agent, leveling agent and defoaming agent and mix evenly to obtain a waterproof coating material; Step S2: Successively carry out electrolytic degreasing, pickling and plasma cleaning on the lead frame to obtain a pretreated lead frame; Step S3: Coat the waterproof coating material on the surface of the pretreated lead frame, and after curing, form a waterproof coating to obtain a waterproof lead frame; The preparation method of the modified graphene oxide is as follows: Step (1): Ultrasonically disperse graphene oxide in N, N - dimethylformamide, add triphenylphosphine and hydroquinone, heat up to 100 - 120 °C, add castor oil triglycidyl ether, react for 10 - 12 h, then add n - octadecyl mercaptan and photoinitiator and mix evenly. After ultraviolet light irradiation, filtration, washing and drying, an intermediate is obtained; Step (2): Ultrasonically disperse the intermediate in N, N - dimethylformamide, add bis - amino - terminated polydimethylsiloxane, adjust the pH to 6 - 8 with sodium hydroxide, react at 30 - 40 °C for 20 - 24 h, and after filtration, washing and drying, modified graphene oxide is obtained.

2. The manufacturing method of a waterproof lead frame for semiconductor packaging according to claim 1, characterized in that: The waterproof coating material includes the following weight components: 60 - 80 parts of waterborne epoxy resin, 80 - 100 parts of deionized water, 3 - 5 parts of modified graphene oxide, 5 - 10 parts of modified halloysite nanotubes, 8 - 12 parts of curing agent, 0.1 - 0.3 parts of leveling agent, 0.1 - 0.2 parts of defoaming agent.

3. The manufacturing method of a waterproof lead frame for semiconductor packaging according to claim 1, characterized in that: In the said step (1), the mass ratio of castor oil triglycidyl ether, n - octadecyl mercaptan and photoinitiator is 1:(1 - 2):(0.1 - 0.3), and the photoinitiator is 2 - hydroxy - 2 - methylpropiophenone.

4. The manufacturing method of a waterproof lead frame for semiconductor packaging according to claim 1, characterized in that: In the said step (2), the mass ratio of the intermediate, N, N - dimethylformamide and bis - amino - terminated polydimethylsiloxane is 1:(100 - 200):(2 - 4).

5. The manufacturing method of a waterproof lead frame for semiconductor packaging according to claim 2, characterized in that: The preparation method of the modified halloysite nanotubes is as follows: Step A: Mix halloysite nanotubes and sodium hydroxide solution evenly, ultrasonically treat at 40 - 50 °C for 1 - 2 h, and after centrifugation, washing and drying, alkali - treated halloysite nanotubes are obtained; Stir the alkali - treated halloysite nanotubes and ethanol solution of benzotriazole for 44 - 48 h, carry out vacuum extraction for 1 - 2 h, then stand at normal pressure for 30 - 50 min, and after filtration, washing and drying, supported halloysite nanotubes are obtained; Step B: Under nitrogen protection, mix polyvinylpyrrolidone and absolute ethanol evenly, then add glycidyl methacrylate, heat up to 70 - 80 °C, add azobisisobutyronitrile, react for 8 - 10 h, and after washing and drying, polyglycidyl methacrylate is obtained; Step C: Mix the supported halloysite nanotubes, absolute ethanol, deionized water and 3-aminopropyltrimethoxysilane evenly, react at 70 - 80 °C for 4 - 6 h, and after filtration, washing and drying, obtain amino-functionalized halloysite nanotubes; Mix the amino-functionalized halloysite nanotubes and poly(glycidyl methacrylate) evenly, add deionized water and disperse by ultrasonic treatment, then react at 40 - 50 °C for 22 - 24 h, and after filtration, washing and drying, obtain modified halloysite nanotubes.

6. The manufacturing method of a waterproof lead frame for semiconductor packaging according to claim 5, characterized in that: In the said Step C, the mass ratio of the amino-functionalized halloysite nanotubes, poly(glycidyl methacrylate) and deionized water is 1:(2 - 3):(100 - 150).

7. The manufacturing method of a waterproof lead frame for semiconductor packaging according to claim 2, characterized in that: The curing agent is isophorone diamine curing agent.

8. A waterproof lead frame for semiconductor packaging prepared by the manufacturing method according to any one of claims 1 - 7.

Images